1
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Pham TD, Verlander JW, Chen C, Pech V, Kim HI, Kim YH, Weiner ID, Milne GL, Zent R, Bock F, Brown D, Eaton A, Wall SM. Angiotensin II acts through Rac1 to upregulate pendrin: role of NADPH oxidase. Am J Physiol Renal Physiol 2024; 326:F202-F218. [PMID: 38059296 DOI: 10.1152/ajprenal.00139.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 11/14/2023] [Accepted: 11/14/2023] [Indexed: 12/08/2023] Open
Abstract
Angiotensin II increases apical plasma membrane pendrin abundance and function. This study explored the role of the small GTPase Rac1 in the regulation of pendrin by angiotensin II. To do this, we generated intercalated cell (IC) Rac1 knockout mice and observed that IC Rac1 gene ablation reduced the relative abundance of pendrin in the apical region of intercalated cells in angiotensin II-treated mice but not vehicle-treated mice. Similarly, the Rac1 inhibitor EHT 1864 reduced apical pendrin abundance in angiotensin II-treated mice, through a mechanism that does not require aldosterone. This IC angiotensin II-Rac1 signaling cascade modulates pendrin subcellular distribution without significantly changing actin organization. However, NADPH oxidase inhibition with APX 115 reduced apical pendrin abundance in vivo in angiotensin II-treated mice. Moreover, superoxide dismutase mimetics reduced Cl- absorption in angiotensin II-treated cortical collecting ducts perfused in vitro. Since Rac1 is an NADPH subunit, Rac1 may modulate pendrin through NADPH oxidase-mediated reactive oxygen species production. Because pendrin gene ablation blunts the pressor response to angiotensin II, we asked if pendrin blunts the angiotensin II-induced increase in kidney superoxide. Although kidney superoxide was similar in vehicle-treated wild-type and pendrin knockout mice, it was lower in angiotensin II-treated pendrin-null kidneys than in wild-type kidneys. We conclude that angiotensin II acts through Rac1, independently of aldosterone, to increase apical pendrin abundance. Rac1 may stimulate pendrin, at least partly, through NADPH oxidase. This increase in pendrin abundance contributes to the increment in blood pressure and kidney superoxide content seen in angiotensin II-treated mice.NEW & NOTEWORTHY This study defines a new signaling mechanism by which angiotensin II modulates oxidative stress and blood pressure.
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Affiliation(s)
- Truyen D Pham
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, The University of Florida College of Medicine, Gainesville, Florida, United States
| | - Chao Chen
- Division of Nephrology, Hypertension and Renal Transplantation, The University of Florida College of Medicine, Gainesville, Florida, United States
| | - Vladimir Pech
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Hailey I Kim
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Young Hee Kim
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, The University of Florida College of Medicine, Gainesville, Florida, United States
- Nephrology and Hypertension Section, Gainesville Veterans Affairs Medical Center, Gainesville, Florida, United States
| | - Ginger L Milne
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Roy Zent
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Veterans Affairs Hospital, Nashville, Tennessee, United States
| | - Fabian Bock
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Veterans Affairs Hospital, Nashville, Tennessee, United States
| | - Dennis Brown
- Program in Membrane Biology, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States
| | - Amity Eaton
- Program in Membrane Biology, Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States
| | - Susan M Wall
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
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2
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Nguyen TT, Bui ATP, Le NTH, Vo HTN, Nguyen AH, Pham TD, Hara T, Yokota K, Matsutani M, Takatsuka Y, Nguyen ATV. Heat-stable spores of carotenoid-producing Bacillus marisflavi and non-pigmented Bacillus subtilis cooperatively promote growth, quality, and gut microbiota of white-leg shrimp. Benef Microbes 2023; 14:623-640. [PMID: 38350466 DOI: 10.1163/18762891-20230041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 10/28/2023] [Indexed: 02/15/2024]
Abstract
We evaluated the benefits of heat-stable carotenoid-producing Bacillus marisflavi SH8 spores individually and in combination with non-pigmented Bacillus subtilis SH23 spores on growth, colour change, nutritional content, innate immunity, and gut microbiota of white-leg shrimp. White-leg shrimp (Litopenaeus vannamei; n = 30 per tank; 2 tanks per group) were provided feed without (control group) or with SH8, SH23, or mixed spores (total, 1 × 106 cfu/g pellet) for 28 d. The SH8 and SH8-23 combination groups had significantly higher specific growth rates (9.6 and 11.0%), improved red-colour score (4 scores), astaxanthin concentration (1.8- and 2.3-fold), lipid contents (30 and 50%), and superoxidase dismutase activity (8.5 and 12.3%) than that of the control group. Analysis of shrimp's gut microbiome using 16S rRNA metagenome sequencing revealed increased abundance of four useful species and reduced abundance of four harmful species in the combination group than in the control group. Heat-stable Bacillus spore combination improved growth parameters, nutrient content, red-colour score, live counts, and abundance of useful bacteria in the gut of L. vannamei. This is the first study to show the benefits of combining highly heat-stable pigmented and non-pigmented Bacillus spores and their possible mechanisms in a shrimp model.
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Affiliation(s)
- T T Nguyen
- Spobiotic Research Center, ANABIO R&D Ltd., Hanoi, Vietnam
| | - A T P Bui
- Spobiotic Research Center, ANABIO R&D Ltd., Hanoi, Vietnam
- Key Laboratory of Enzyme and Protein Technology, VNU University of Science, Vietnam National University Hanoi, Hanoi, Vietnam
| | - N T H Le
- Key Laboratory of Enzyme and Protein Technology, VNU University of Science, Vietnam National University Hanoi, Hanoi, Vietnam
| | - H T N Vo
- Key Laboratory of Enzyme and Protein Technology, VNU University of Science, Vietnam National University Hanoi, Hanoi, Vietnam
| | - A H Nguyen
- Spobiotic Research Center, ANABIO R&D Ltd., Hanoi, Vietnam
- LiveSpo Pharma Ltd. Company, Hanoi, Vietnam
| | - T D Pham
- Faculty of Mathematics-Mechanics-Informatics, VNU University of Science, Vietnam National University Hanoi, Hanoi, Vietnam
| | - T Hara
- Environmental Microbiology Research Section, Laboratory for Complex Energy Processes, Institute of Advanced Energy, Kyoto University, Kyoto, Japan
| | - K Yokota
- Department of Agricultural Chemistry, Tokyo University of Agriculture, Tokyo, Japan
| | - M Matsutani
- Genome Research Center, Tokyo University of Agriculture, Tokyo, Japan
| | - Y Takatsuka
- Environmental Microbiology Research Section, Laboratory for Complex Energy Processes, Institute of Advanced Energy, Kyoto University, Kyoto, Japan
| | - A T V Nguyen
- Spobiotic Research Center, ANABIO R&D Ltd., Hanoi, Vietnam
- Key Laboratory of Enzyme and Protein Technology, VNU University of Science, Vietnam National University Hanoi, Hanoi, Vietnam
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3
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Al-Qusairi L, Ferdaus MZ, Pham TD, Li D, Grimm PR, Zapf AM, Abood DC, Tahaei E, Delpire E, Wall SM, Welling PA. Dietary anions control potassium excretion: it is more than a poorly absorbable anion effect. Am J Physiol Renal Physiol 2023; 325:F377-F393. [PMID: 37498547 PMCID: PMC10639028 DOI: 10.1152/ajprenal.00193.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 07/28/2023] Open
Abstract
The urinary potassium (K+) excretion machinery is upregulated with increasing dietary K+, but the role of accompanying dietary anions remains inadequately characterized. Poorly absorbable anions, including [Formula: see text], are thought to increase K+ secretion through a transepithelial voltage effect. Here, we tested if they also influence the K+ secretion machinery. Wild-type mice, aldosterone synthase (AS) knockout (KO) mice, or pendrin KO mice were randomized to control, high-KCl, or high-KHCO3 diets. The K+ secretory capacity was assessed in balance experiments. Protein abundance, modification, and localization of K+-secretory transporters were evaluated by Western blot analysis and confocal microscopy. Feeding the high-KHCO3 diet increased urinary K+ excretion and the transtubular K+ gradient significantly more than the high-KCl diet, coincident with more pronounced upregulation of epithelial Na+ channels (ENaC) and renal outer medullary K+ (ROMK) channels and apical localization in the distal nephron. Experiments in AS KO mice revealed that the enhanced effects of [Formula: see text] were aldosterone independent. The high-KHCO3 diet also uniquely increased the large-conductance Ca2+-activated K+ (BK) channel β4-subunit, stabilizing BKα on the apical membrane, the Cl-/[Formula: see text] exchanger, pendrin, and the apical KCl cotransporter (KCC3a), all of which are expressed specifically in pendrin-positive intercalated cells. Experiments in pendrin KO mice revealed that pendrin was required to increase K+ excretion with the high-KHCO3 diet. In summary, [Formula: see text] stimulates K+ excretion beyond a poorly absorbable anion effect, upregulating ENaC and ROMK in principal cells and BK, pendrin, and KCC3a in pendrin-positive intercalated cells. The adaptive mechanism prevents hyperkalemia and alkalosis with the consumption of alkaline ash-rich diets but may drive K+ wasting and hypokalemia in alkalosis.NEW & NOTEWORTHY Dietary anions profoundly impact K+ homeostasis. Here, we found that a K+-rich diet, containing [Formula: see text] as the counteranion, enhances the electrogenic K+ excretory machinery, epithelial Na+ channels, and renal outer medullary K+ channels, much more than a high-KCl diet. It also uniquely induces KCC3a and pendrin, in B-intercalated cells, providing an electroneutral KHCO3 secretion pathway. These findings reveal new K+ balance mechanisms that drive adaption to alkaline and K+-rich foods, which should guide new treatment strategies for K+ disorders.
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Affiliation(s)
- Lama Al-Qusairi
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Mohammed Z Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Truyen D Pham
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Dimin Li
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - P Richard Grimm
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Ava M Zapf
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Delaney C Abood
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Ebrahim Tahaei
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Susan M Wall
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Paul A Welling
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
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4
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Loffing J, Pech V, Loffing-Cueni D, Abood DC, Kim YH, Chen C, Pham TD, Verlander JW, Wall SM. Pendrin abundance, subcellular distribution, and function are unaffected by either αENaC gene ablation or by increasing ENaC channel activity. Pflugers Arch 2023; 475:607-620. [PMID: 36977894 PMCID: PMC10105674 DOI: 10.1007/s00424-023-02797-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/20/2023] [Accepted: 02/13/2023] [Indexed: 03/30/2023]
Abstract
The intercalated cell Cl-/HCO3- exchanger, pendrin, modulates ENaC subunit abundance and function. Whether ENaC modulates pendrin abundance and function is however unknown. Because αENaC mRNA has been detected in pendrin-positive intercalated cells, we hypothesized that ENaC, or more specifically the αENaC subunit, modulates intercalated cell function. The purpose of this study was therefore to determine if αENaC is expressed at the protein level in pendrin-positive intercalated cells and to determine if αENaC gene ablation or constitutively upregulating ENaC activity changes pendrin abundance, subcellular distribution, and/or function. We observed diffuse, cytoplasmic αENaC label in pendrin-positive intercalated cells from both mice and rats, with much lower label intensity in pendrin-negative, type A intercalated cells. However, while αENaC gene ablation within principal and intercalated cells of the CCD reduced Cl- absorption, it did not change pendrin abundance or subcellular distribution in aldosterone-treated mice. Further experiments used a mouse model of Liddle's syndrome to explore the effect of increasing ENaC channel activity on pendrin abundance and function. The Liddle's variant did not increase either total or apical plasma membrane pendrin abundance in aldosterone-treated or in NaCl-restricted mice. Similarly, while the Liddle's mutation increased total Cl- absorption in CCDs from aldosterone-treated mice, it did not significantly affect the change in Cl- absorption seen with pendrin gene ablation. We conclude that in rats and mice, αENaC localizes to pendrin-positive ICs where its physiological role remains to be determined. While pendrin modulates ENaC abundance, subcellular distribution, and function, ENaC does not have a similar effect on pendrin.
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Affiliation(s)
- Johannes Loffing
- Institute of Anatomy, University of Zurich, Zurich, Switzerland.
| | - Vladimir Pech
- Division of Renal Medicine, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
| | | | - Delaney C Abood
- Division of Renal Medicine, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Young Hee Kim
- Division of Renal Medicine, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Chao Chen
- The Division of Nephrology, Hypertension and Renal Transplantation, The University of Florida College of Medicine, Gainesville, FL, USA
| | - Truyen D Pham
- Division of Renal Medicine, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Jill W Verlander
- The Division of Nephrology, Hypertension and Renal Transplantation, The University of Florida College of Medicine, Gainesville, FL, USA
| | - Susan M Wall
- Division of Renal Medicine, Department of Medicine, Emory University, Atlanta, GA, 30322, USA.
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5
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Huang JH, Wittekind SG, Opotowsky AR, Ward K, Lyman A, Gauthier N, Vernon M, Powell AW, White DA, Curran TJ, Orr WB, Stephens P, Robinson B, Pham TD, Mays WA, Burstein D, Carr M, Paridon S, Rhodes J, Koenig P. Pediatric Cardiology Fellowship Standards for Training in Exercise Medicine and Curriculum Outline. Pediatr Cardiol 2023; 44:540-548. [PMID: 36422652 DOI: 10.1007/s00246-022-03048-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 11/04/2022] [Indexed: 11/25/2022]
Abstract
Over the past 2 decades, fundamentals of exercise medicine, including clinical exercise testing, assessment and promotion of physical activity, exercise prescription, and supervised exercise training/rehabilitation programming have demonstrated considerable clinical value in the management of children and adolescents with congenital and acquired heart disease. Although the principles of exercise medicine have become an integral component in pediatric cardiology, there are no standardized training recommendations for exercise physiology during pediatric cardiology fellowship at this time. Thus, the Pediatric Cardiology Exercise Medicine Curriculum Committee (PCEMCC) was formed to establish core and advanced exercise physiology training recommendations for pediatric cardiology trainees. The PCEMCC includes a diverse group of pediatric cardiologists, exercise physiologists, and fellowship program directors. The expert consensus training recommendations are by no means a mandate and are summarized herein, including suggestions for achieving the minimum knowledge and training needed for general pediatric cardiology practice.
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Affiliation(s)
- J H Huang
- Department of Pediatrics, Doernbecher Children's Hospital, Oregon Health and Science University, Portland, OR, USA.
| | - S G Wittekind
- Division of Cardiology, Seattle Children's Hospital, Seattle, WA, USA
| | - A R Opotowsky
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - K Ward
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - A Lyman
- Department of Pediatrics, Doernbecher Children's Hospital, Oregon Health and Science University, Portland, OR, USA
| | - N Gauthier
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
| | - M Vernon
- Division of Cardiology, Seattle Children's Hospital, Seattle, WA, USA
| | - A W Powell
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - D A White
- Ward Family Heart Center, Children's Mercy Hospital, Kansas City, MO, USA
| | - T J Curran
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
| | - W B Orr
- Division of Pediatric Cardiology, Washington University School of Medicine, St. Louis, MO, USA
| | - P Stephens
- Division of Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - B Robinson
- Nemours Cardiac Center, Alfred I DuPont Hospital for Children, Wilmington, DE, USA
| | - T D Pham
- Department of Cardiology, Texas Children's Hospital, Houston, TX, USA
| | - W A Mays
- The Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - D Burstein
- Division of Pediatric Cardiology, University of Vermont, Burlington, VT, USA
| | - M Carr
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - S Paridon
- Division of Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - J Rhodes
- Department of Cardiology, Boston Children's Hospital, Boston, MA, USA
| | - P Koenig
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Division of Cardiology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
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6
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Tahaei E, Pham TD, Al-Qusairi L, Grimm R, Wall SM, Welling PA. Pendrin regulation is prioritized by anion in high-potassium diets. Am J Physiol Renal Physiol 2023; 324:F256-F266. [PMID: 36656986 PMCID: PMC9942896 DOI: 10.1152/ajprenal.00128.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 12/21/2022] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
The Cl-/[Formula: see text] exchanger pendrin in the kidney maintains acid-base balance and intravascular volume. Pendrin is upregulated in models associated with high circulating aldosterone concentration, such as dietary NaCl restriction or an aldosterone infusion. However, it has not been established if pendrin is similarly regulated by aldosterone with a high-K+ diet because the effects of accompanying anions have not been considered. Here, we explored how pendrin is modulated by different dietary potassium salts. Wild-type (WT) and aldosterone synthase (AS) knockout (KO) mice were randomized to control, high-KHCO3, or high-KCl diets. Dietary KCl and KHCO3 loading increased aldosterone in WT mice to the same extent but had opposite effects on pendrin abundance. KHCO3 loading increased pendrin protein and transcript abundance. Conversely, high-KCl diet feeding caused pendrin to decrease within 8 h of switching from the high-KHCO3 diet, coincident with an increase in plasma Cl- and a decrease in [Formula: see text]. In contrast, switching the high-KCl diet to the high-KHCO3 diet caused pendrin to increase in WT mice. Experiments in AS KO mice revealed that aldosterone is necessary to optimally upregulate pendrin protein in response to the high-KHCO3 diet but not to increase pendrin mRNA. We conclude that pendrin is differentially regulated by different dietary potassium salts and that its regulation is prioritized by the dietary anion, providing a mechanism to prevent metabolic alkalosis with high-K+ base diets and safeguard against hyperchloremic acidosis with consumption of high-KCl diets.NEW & NOTEWORTHY Regulation of the Cl-/[Formula: see text] exchanger pendrin has been suggested to explain the aldosterone paradox. A high-K+ diet has been proposed to downregulate a pendrin-mediated K+-sparing NaCl reabsorption pathway to maximize urinary K+ excretion. Here, we challenged the hypothesis, revealing that the accompanying anion, not K+, drives pendrin expression. Pendrin is downregulated with a high-KCl diet, preventing acidosis, and upregulated with an alkaline-rich high-K+ diet, preventing metabolic alkalosis. Pendrin regulation is prioritized for acid-base balance.
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Affiliation(s)
- Ebrahim Tahaei
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Truyen D Pham
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Lama Al-Qusairi
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Rick Grimm
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Paul A Welling
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
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7
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Pham TD, Elengickal AJ, Verlander JW, Al-Qusairi L, Chen C, Abood DC, King SA, Loffing J, Welling PA, Wall SM. Pendrin-null mice develop severe hypokalemia following dietary Na + and K + restriction: role of ENaC. Am J Physiol Renal Physiol 2022; 322:F486-F497. [PMID: 35224991 PMCID: PMC8977139 DOI: 10.1152/ajprenal.00378.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pendrin is an intercalated cell Cl-/[Formula: see text] exchanger thought to participate in K+-sparing NaCl absorption. However, its role in K+ homeostasis has not been clearly defined. We hypothesized that pendrin-null mice will develop hypokalemia with dietary K+ restriction. We further hypothesized that pendrin knockout (KO) mice mitigate urinary K+ loss by downregulating the epithelial Na+ channel (ENaC). Thus, we examined the role of ENaC in Na+ and K+ balance in pendrin KO and wild-type mice following dietary K+ restriction. To do so, we examined the relationship between Na+ and K+ balance and ENaC subunit abundance in K+-restricted pendrin-null and wild-type mice that were NaCl restricted or replete. Following a NaCl-replete, K+-restricted diet, K+ balance and serum K+ were similar in both groups. However, following a Na+, K+, and Cl--deficient diet, pendrin KO mice developed hypokalemia from increased K+ excretion. The fall in serum K+ observed in K+-restricted pendrin KO mice was enhanced with ENaC stimulation but eliminated with ENaC inhibition. The fall in serum K+ observed in K+-restricted pendrin KO mice was enhanced with ENaC stimulation but eliminated with ENaC inhibition. However, reducing ENaC activity also reduced blood pressure and increased apparent intravascular volume contraction, since KO mice had lower serum Na+, higher blood urea nitrogen and hemoglobin, greater weight loss, greater metabolic alkalosis, and greater NaCl excretion. We conclude that dietary Na+ and K+ restriction induces hypokalemia in pendrin KO mice. Pendrin-null mice limit renal K+ loss by downregulating ENaC. However, this ENaC downregulation occurs at the expense of intravascular volume.NEW & NOTEWORTHY Pendrin is an apical Cl-/[Formula: see text] exchanger that provides renal K+-sparing NaCl absorption. The pendrin-null kidney has an inability to fully conserve K+ and limits renal K+ loss by downregulating the epithelial Na+ channel (ENaC). However, with Na+ restriction, the need to reduce ENaC for K+ balance conflicts with the need to stimulate ENaC for intravascular volume. Therefore, NaCl restriction stimulates ENaC less in pendrin-null mice than in wild-type mice, which mitigates their kaliuresis and hypokalemia but exacerbates volume contraction.
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Affiliation(s)
- Truyen D Pham
- Department of Medicine, Division of Nephrology, Emory University School of Medicine, Atlanta, Georgia
| | - Anthony J Elengickal
- Department of Medicine, Division of Nephrology, Emory University School of Medicine, Atlanta, Georgia
| | - Jill W Verlander
- Department of Medicine, University of Florida, Gainesville, Florida
| | - Lama Al-Qusairi
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Chao Chen
- Department of Medicine, University of Florida, Gainesville, Florida
| | - Delaney C Abood
- Department of Medicine, Division of Nephrology, Emory University School of Medicine, Atlanta, Georgia
| | - Spencer A King
- Department of Medicine, Division of Nephrology, Emory University School of Medicine, Atlanta, Georgia
| | - Johannes Loffing
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Paul A Welling
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Susan M Wall
- Department of Medicine, Division of Nephrology, Emory University School of Medicine, Atlanta, Georgia
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8
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Yasuoka Y, Izumi Y, Fukuyama T, Omiya H, Pham TD, Inoue H, Oshima T, Yamazaki T, Uematsu T, Kobayashi N, Shimada Y, Nagaba Y, Yamashita T, Mukoyama M, Sato Y, Wall SM, Sands JM, Takahashi N, Kawahara K, Nonoguchi H. Effects of Roxadustat on Erythropoietin Production in the Rat Body. Molecules 2022; 27:1119. [PMID: 35164384 PMCID: PMC8838165 DOI: 10.3390/molecules27031119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 12/19/2022] Open
Abstract
Anemia is a major complication of chronic renal failure. To treat this anemia, prolylhydroxylase domain enzyme (PHD) inhibitors as well as erythropoiesis-stimulating agents (ESAs) have been used. Although PHD inhibitors rapidly stimulate erythropoietin (Epo) production, the precise sites of Epo production following the administration of these drugs have not been identified. We developed a novel method for the detection of the Epo protein that employs deglycosylation-coupled Western blotting. With protein deglycosylation, tissue Epo contents can be quantified over an extremely wide range. Using this method, we examined the effects of the PHD inhibitor, Roxadustat (ROX), and severe hypoxia on Epo production in various tissues in rats. We observed that ROX increased Epo mRNA expression in both the kidneys and liver. However, Epo protein was detected in the kidneys but not in the liver. Epo protein was also detected in the salivary glands, spleen, epididymis and ovaries. However, both PHD inhibitors (ROX) and severe hypoxia increased the Epo protein abundance only in the kidneys. These data show that, while Epo is produced in many tissues, PHD inhibitors as well as severe hypoxia regulate Epo production only in the kidneys.
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Affiliation(s)
- Yukiko Yasuoka
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (Y.Y.); (T.O.); (N.T.); (K.K.)
| | - Yuichiro Izumi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Kumamoto, Japan; (Y.I.); (H.I.); (M.M.)
| | - Takashi Fukuyama
- Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (T.F.); (T.Y.); (T.U.); (N.K.)
| | - Haruki Omiya
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Iwate, Japan; (H.O.); (T.Y.)
| | - Truyen D. Pham
- Renal Division, Department of Medicine, Emory University School of Medicine, 1639 Pierce Drive, WMB Room 3313, Atlanta, GA 30322, USA; (T.D.P.); (S.M.W.); (J.M.S.)
| | - Hideki Inoue
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Kumamoto, Japan; (Y.I.); (H.I.); (M.M.)
| | - Tomomi Oshima
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (Y.Y.); (T.O.); (N.T.); (K.K.)
| | - Taiga Yamazaki
- Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (T.F.); (T.Y.); (T.U.); (N.K.)
| | - Takayuki Uematsu
- Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (T.F.); (T.Y.); (T.U.); (N.K.)
| | - Noritada Kobayashi
- Division of Biomedical Research, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (T.F.); (T.Y.); (T.U.); (N.K.)
| | - Yoshitaka Shimada
- Division of Internal Medicine, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (Y.S.); (Y.N.)
| | - Yasushi Nagaba
- Division of Internal Medicine, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (Y.S.); (Y.N.)
| | - Tetsuro Yamashita
- Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Iwate, Japan; (H.O.); (T.Y.)
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Kumamoto, Japan; (Y.I.); (H.I.); (M.M.)
| | - Yuichi Sato
- Department of Molecular Diagnostics, Kitasato University School of Allied Health Sciences, Sagamihara 252-0373, Kanagawa, Japan;
| | - Susan M. Wall
- Renal Division, Department of Medicine, Emory University School of Medicine, 1639 Pierce Drive, WMB Room 3313, Atlanta, GA 30322, USA; (T.D.P.); (S.M.W.); (J.M.S.)
| | - Jeff M. Sands
- Renal Division, Department of Medicine, Emory University School of Medicine, 1639 Pierce Drive, WMB Room 3313, Atlanta, GA 30322, USA; (T.D.P.); (S.M.W.); (J.M.S.)
| | - Noriko Takahashi
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (Y.Y.); (T.O.); (N.T.); (K.K.)
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara 252-0374, Kanagawa, Japan; (Y.Y.); (T.O.); (N.T.); (K.K.)
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, 6-100 Arai, Kitamoto 364-8501, Saitama, Japan; (Y.S.); (Y.N.)
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9
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Tan CWJ, Gouramanis C, Pham TD, Hoang DQ, Switzer AD. Ostracods as pollution indicators in Lap An Lagoon, central Vietnam. Environ Pollut 2021; 278:116762. [PMID: 33725531 DOI: 10.1016/j.envpol.2021.116762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 01/28/2021] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
Southeast Asia is particularly susceptible to the negative impacts of increasing coastal pollution as coastal populations and cities grow at unprecedented rates. Although water chemistry can be monitored, there are greater advantages in using bioindicators as reflectors of the combined effect of multiple pollution types on coastal ecosystem health and for early detection of the negative impacts of pollutants on biotic systems. This study explores the utility and application of ostracods as pollution bioindicators and examines the response of ostracod assemblages to variable pollution in Lap An Lagoon, central Vietnam. From 14 sites within the lagoon, 79 species of 46 genera were identified and sediment grain size, total organic carbon, organic matter and heavy metal concentration were measured. Cluster analysis, detrended correspondence analysis and canonical correspondence analysis identified four distinct ostracod biofacies that were highly correlated to the physical environmental variables (salinity, depth, sediment type, heavy metal concentrations, total organic carbon and organic matter) and are shown to be the main factors controlling ostracod biofacies. Low ostracod diversities were found in silty sediments with heavy metal concentrations likely toxic. Sinocytheridea impressa was indicative of a marginally polluted environment within the lagoon. This study provides evidence for the potential for Southeast Asian ostracods to be used in water quality assessments and the data collected can be used as a baseline for future pollution monitoring.
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Affiliation(s)
- C W J Tan
- Department of Geography, National University of Singapore, Singapore
| | - C Gouramanis
- Research School of Earth Sciences, The Australian National University, Canberra, Australia.
| | - T D Pham
- VNU University of Science, Vietnam National University, Hanoi, Viet Nam
| | - D Q Hoang
- Hanoi University of Mining and Geology, Hanoi, Viet Nam
| | - A D Switzer
- Asian School of the Environment, Nanyang Technological University, Singapore; Earth Observatory of Singapore, Nanyang Technological University, Singapore
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10
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Pham TD, Verlander JW, Wang Y, Romero CA, Yue Q, Chen C, Thumova M, Eaton DC, Lazo-Fernandez Y, Wall SM. Aldosterone Regulates Pendrin and Epithelial Sodium Channel Activity through Intercalated Cell Mineralocorticoid Receptor-Dependent and -Independent Mechanisms over a Wide Range in Serum Potassium. J Am Soc Nephrol 2020. [PMID: 32054691 DOI: 10.1152/ajprenal.90637.2008.-ammonia] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Abstract
BACKGROUND Aldosterone activates the intercalated cell mineralocorticoid receptor, which is enhanced with hypokalemia. Whether this receptor directly regulates the intercalated cell chloride/bicarbonate exchanger pendrin is unclear, as are potassium's role in this response and the receptor's effect on intercalated and principal cell function in the cortical collecting duct (CCD). METHODS We measured CCD chloride absorption, transepithelial voltage, epithelial sodium channel activity, and pendrin abundance and subcellular distribution in wild-type and intercalated cell-specific mineralocorticoid receptor knockout mice. To determine if the receptor directly regulates pendrin, as well as the effect of serum aldosterone and potassium on this response, we measured pendrin label intensity and subcellular distribution in wild-type mice, knockout mice, and receptor-positive and receptor-negative intercalated cells from the same knockout mice. RESULTS Ablation of the intercalated cell mineralocorticoid receptor in CCDs from aldosterone-treated mice reduced chloride absorption and epithelial sodium channel activity, despite principal cell mineralocorticoid receptor expression in the knockout mice. With high circulating aldosterone, intercalated cell mineralocorticoid receptor gene ablation directly reduced pendrin's relative abundance in the apical membrane region and pendrin abundance per cell whether serum potassium was high or low. Intercalated cell mineralocorticoid receptor ablation blunted, but did not eliminate, aldosterone's effect on pendrin total and apical abundance and subcellular distribution. CONCLUSIONS With high circulating aldosterone, intercalated cell mineralocorticoid receptor ablation reduces chloride absorption in the CCD and indirectly reduces principal cell epithelial sodium channel abundance and function. This receptor directly regulates pendrin's total abundance and its relative abundance in the apical membrane region over a wide range in serum potassium concentration. Aldosterone regulates pendrin through mechanisms both dependent and independent of the IC MR receptor.
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Affiliation(s)
| | - Jill W Verlander
- Department of Medicine, University of Florida, Gainesville, Florida
| | | | | | | | - Chao Chen
- Department of Medicine, University of Florida, Gainesville, Florida
| | | | - Douglas C Eaton
- Departments of Medicine and
- Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | | | - Susan M Wall
- Departments of Medicine and
- Physiology, Emory University School of Medicine, Atlanta, Georgia; and
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11
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Pham TD, Verlander JW, Wang Y, Romero CA, Yue Q, Chen C, Thumova M, Eaton DC, Lazo-Fernandez Y, Wall SM. Aldosterone Regulates Pendrin and Epithelial Sodium Channel Activity through Intercalated Cell Mineralocorticoid Receptor-Dependent and -Independent Mechanisms over a Wide Range in Serum Potassium. J Am Soc Nephrol 2020; 31:483-499. [PMID: 32054691 DOI: 10.1681/asn.2019050551] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/14/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Aldosterone activates the intercalated cell mineralocorticoid receptor, which is enhanced with hypokalemia. Whether this receptor directly regulates the intercalated cell chloride/bicarbonate exchanger pendrin is unclear, as are potassium's role in this response and the receptor's effect on intercalated and principal cell function in the cortical collecting duct (CCD). METHODS We measured CCD chloride absorption, transepithelial voltage, epithelial sodium channel activity, and pendrin abundance and subcellular distribution in wild-type and intercalated cell-specific mineralocorticoid receptor knockout mice. To determine if the receptor directly regulates pendrin, as well as the effect of serum aldosterone and potassium on this response, we measured pendrin label intensity and subcellular distribution in wild-type mice, knockout mice, and receptor-positive and receptor-negative intercalated cells from the same knockout mice. RESULTS Ablation of the intercalated cell mineralocorticoid receptor in CCDs from aldosterone-treated mice reduced chloride absorption and epithelial sodium channel activity, despite principal cell mineralocorticoid receptor expression in the knockout mice. With high circulating aldosterone, intercalated cell mineralocorticoid receptor gene ablation directly reduced pendrin's relative abundance in the apical membrane region and pendrin abundance per cell whether serum potassium was high or low. Intercalated cell mineralocorticoid receptor ablation blunted, but did not eliminate, aldosterone's effect on pendrin total and apical abundance and subcellular distribution. CONCLUSIONS With high circulating aldosterone, intercalated cell mineralocorticoid receptor ablation reduces chloride absorption in the CCD and indirectly reduces principal cell epithelial sodium channel abundance and function. This receptor directly regulates pendrin's total abundance and its relative abundance in the apical membrane region over a wide range in serum potassium concentration. Aldosterone regulates pendrin through mechanisms both dependent and independent of the IC MR receptor.
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Affiliation(s)
| | - Jill W Verlander
- Department of Medicine, University of Florida, Gainesville, Florida
| | | | | | | | - Chao Chen
- Department of Medicine, University of Florida, Gainesville, Florida
| | | | - Douglas C Eaton
- Departments of Medicine and.,Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | | | - Susan M Wall
- Departments of Medicine and .,Physiology, Emory University School of Medicine, Atlanta, Georgia; and
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12
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Park AY, Plotsky PM, Pham TD, Pacak K, Wynne BM, Wall SM, Lazo‐Fernandez Y. Blood collection in unstressed, conscious, and freely moving mice through implantation of catheters in the jugular vein: a new simplified protocol. Physiol Rep 2018; 6:e13904. [PMID: 30426706 PMCID: PMC6234146 DOI: 10.14814/phy2.13904] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 09/26/2018] [Accepted: 09/27/2018] [Indexed: 02/06/2023] Open
Abstract
The mouse has become the most common mammalian animal model used in biomedical research. However, laboratory techniques used previously in rats and other larger animals to sample blood had to be adapted in mice due to their lower mouse plasma volume. Sampling is further confounded by the variability in plasma hormone and metabolite concentrations that can occur from the stress or the anesthesia that accompanies the collection. In this article, we describe in detail a protocol we developed for blood sampling in conscious, unrestrained mice. Our protocol implements the use of chronic indwelling catheters in the right external jugular vein, allowing the mice to recover fully in their home cages, untethered until the time of blood sampling. This protocol employs catheters that remain patent for days and does not require the purchase of expensive equipment. We validated this protocol by measuring the time course of plasma norepinephrine (NE) concentration during and after the relief of acute immobilization stress in wild type (WT) and pendrin knockout (KO) mice and compared these results with our previously published values. We found that following relief from immobilization stress, it takes longer for plasma NE concentration to return to basal levels in the pendrin KO than in the wild type mice. These results highlight the potential utility of this protocol and the potential role of pendrin in the neuroendocrine response to acute stress.
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Affiliation(s)
- Annie Y. Park
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Paul M. Plotsky
- Department of Psychiatry & Behavioral SciencesEmory University School of MedicineAtlantaGeorgia
| | - Truyen D. Pham
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Karel Pacak
- Program in Reproductive and Adult EndocrinologyEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMaryland
| | - Brandi M. Wynne
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Susan M. Wall
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
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13
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Nanami M, Pham TD, Kim YH, Yang B, Sutliff RL, Staub O, Klein JD, Lopez-Cayuqueo KI, Chambrey R, Park AY, Wang X, Pech V, Verlander JW, Wall SM. The Role of Intercalated Cell Nedd4-2 in BP Regulation, Ion Transport, and Transporter Expression. J Am Soc Nephrol 2018; 29:1706-1719. [PMID: 29773687 DOI: 10.1681/asn.2017080826] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 03/29/2018] [Indexed: 12/23/2022] Open
Abstract
BackgroundNedd4-2 is an E3 ubiquitin-protein ligase that associates with transport proteins, causing their ubiquitylation, and then internalization and degradation. Previous research has suggested a correlation between Nedd4-2 and BP. In this study, we explored the effect of intercalated cell (IC) Nedd4-2 gene ablation on IC transporter abundance and function and on BP.Methods We generated IC Nedd4-2 knockout mice using Cre-lox technology and produced global pendrin/Nedd4-2 null mice by breeding global Nedd4-2 null (Nedd4-2-/- ) mice with global pendrin null (Slc26a4-/- ) mice. Mice ate a diet with 1%-4% NaCl; BP was measured by tail cuff and radiotelemetry. We measured transepithelial transport of Cl- and total CO2 and transepithelial voltage in cortical collecting ducts perfused in vitro Transporter abundance was detected with immunoblots, immunohistochemistry, and immunogold cytochemistry.Results IC Nedd4-2 gene ablation markedly increased electroneutral Cl-/HCO3- exchange in the cortical collecting duct, although benzamil-, thiazide-, and bafilomycin-sensitive ion flux changed very little. IC Nedd4-2 gene ablation did not increase the abundance of type B IC transporters, such as AE4 (Slc4a9), H+-ATPase, barttin, or the Na+-dependent Cl-/HCO3- exchanger (Slc4a8). However, IC Nedd4-2 gene ablation increased CIC-5 total protein abundance, apical plasma membrane pendrin abundance, and the ratio of pendrin expression on the apical membrane to the cytoplasm. IC Nedd4-2 gene ablation increased BP by approximately 10 mm Hg. Moreover, pendrin gene ablation eliminated the increase in BP observed in global Nedd4-2 knockout mice.Conclusions IC Nedd4-2 regulates Cl-/HCO3- exchange in ICs., Nedd4-2 gene ablation increases BP in part through its action in these cells.
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Affiliation(s)
| | | | | | - Baoli Yang
- Department of Obstetrics and Gynecology, University of Iowa, Iowa City, Iowa
| | | | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.ch," Zurich, Switzerland
| | | | - Karen I Lopez-Cayuqueo
- Centro de Estudios Cientificos, Valdivia, Chile.,Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Université Paris-Descartes, Paris, France
| | - Regine Chambrey
- Institut National de la Santé et de la Recherche Médicale U1188, Universite de la Reunion, Plateforme Cyclotron Réunion Océan Indien, St. Denis, Ile de la Reunion, France; and
| | | | | | | | - Jill W Verlander
- Renal Division, Department of Medicine, University of Florida at Gainesville, Gainesville, Florida
| | - Susan M Wall
- Renal and .,Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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14
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Tran DN, Tran HH, Matsui M, Suzuki M, Suzuki S, Shibayama K, Pham TD, Van Phuong TT, Dang DA, Trinh HS, Loan CT, Nga LTV, van Doorn HR, Wertheim HFL. Emergence of New Delhi metallo-beta-lactamase 1 and other carbapenemase-producing Acinetobacter calcoaceticus-baumannii complex among patients in hospitals in Ha Noi, Viet Nam. Eur J Clin Microbiol Infect Dis 2016; 36:219-225. [PMID: 27714593 PMCID: PMC5253155 DOI: 10.1007/s10096-016-2784-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 09/05/2016] [Indexed: 11/29/2022]
Abstract
Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.
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Affiliation(s)
- D N Tran
- National Institute of Hygiene and Epidemiology, Yersin 1, Hanoi, Vietnam
| | - H H Tran
- National Institute of Hygiene and Epidemiology, Yersin 1, Hanoi, Vietnam.
| | - M Matsui
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - M Suzuki
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - S Suzuki
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - K Shibayama
- Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - T D Pham
- National Institute of Hygiene and Epidemiology, Yersin 1, Hanoi, Vietnam
| | - T T Van Phuong
- National Institute of Hygiene and Epidemiology, Yersin 1, Hanoi, Vietnam
| | - D A Dang
- National Institute of Hygiene and Epidemiology, Yersin 1, Hanoi, Vietnam
| | | | - C T Loan
- Saint Paul Hospital, Hanoi, Vietnam
| | | | - H R van Doorn
- Oxford University Clinical Research Unit, Hanoi, Vietnam; Nuffield Department of Clinical Medicine, Centre for Tropical Medicine, University of Oxford, Oxford, UK
| | - H F L Wertheim
- Oxford University Clinical Research Unit, Hanoi, Vietnam; Nuffield Department of Clinical Medicine, Centre for Tropical Medicine, University of Oxford, Oxford, UK.,Department of Clinical Microbiology, Radboud UMC, Nijmegen, Netherlands
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15
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Su R, Zhang C, Pham TD, Davey R, Bischof L, Vallotton P, Lovell D, Hope S, Schmoelzl S, Sun C. Detection of tubule boundaries based on circular shortest path and polar-transformation of arbitrary shapes. J Microsc 2016; 264:127-142. [PMID: 27172164 DOI: 10.1111/jmi.12421] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 04/05/2016] [Indexed: 12/25/2022]
Abstract
In studies of germ cell transplantation, counting cells and measuring tubule diameters from different populations using labelled antibodies are important measurement processes. However, it is slow and sanity grinding to do these tasks manually. This paper proposes a way to accelerate these processes using a new image analysis framework based on several novel algorithms: centre points detection of tubules, tubule shape classification, skeleton-based polar-transformation, boundary weighting of polar-transformed image, and circular shortest path smoothing. The framework has been tested on a dataset consisting of 27 images which contain a total of 989 tubules. Experiments show that the detection results of our algorithm are very close to the results obtained manually and the novel approach can achieve a better performance than two existing methods.
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Affiliation(s)
- R Su
- School of Computer Software, Tianjin University, China
| | - C Zhang
- CSIRO Data61, Epping, NSW, Australia. .,School of Engineering and Information Technology, The University of New South Wales, Canberra, ACT, Australia.
| | - T D Pham
- Department of Biomedical Engineering, Linköping University, Linköping, Sweden
| | - R Davey
- CSIRO Food and Nutrition, Armidale, NSW, Australia
| | - L Bischof
- CSIRO Data61, Epping, NSW, Australia
| | | | - D Lovell
- CSIRO Data61, Acton, ACT, Australia
| | - S Hope
- CSIRO Food and Nutrition, St. Lucia, Qld, Australia
| | - S Schmoelzl
- CSIRO Food and Nutrition, Armidale, NSW, Australia
| | - C Sun
- CSIRO Data61, Epping, NSW, Australia
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16
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Lazo-Fernandez Y, Aguilera G, Pham TD, Park AY, Beierwaltes WH, Sutliff RL, Verlander JW, Pacak K, Osunkoya AO, Ellis CL, Kim YH, Shipley GL, Wynne BM, Hoover RS, Sen SK, Plotsky PM, Wall SM. Pendrin localizes to the adrenal medulla and modulates catecholamine release. Am J Physiol Endocrinol Metab 2015; 309:E534-45. [PMID: 26173457 PMCID: PMC4572452 DOI: 10.1152/ajpendo.00035.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 07/09/2015] [Indexed: 02/02/2023]
Abstract
Pendrin (Slc26a4) is a Cl(-)/HCO3 (-) exchanger expressed in renal intercalated cells and mediates renal Cl(-) absorption. With pendrin gene ablation, blood pressure and vascular volume fall, which increases plasma renin concentration. However, serum aldosterone does not significantly increase in pendrin-null mice, suggesting that pendrin regulates adrenal zona glomerulosa aldosterone production. Therefore, we examined pendrin expression in the adrenal gland using PCR, immunoblots, and immunohistochemistry. Pendrin protein was detected in adrenal lysates from wild-type but not pendrin-null mice. However, immunohistochemistry and qPCR of microdissected adrenal zones showed that pendrin was expressed in the adrenal medulla, rather than in cortex. Within the adrenal medulla, pendrin localizes to both epinephrine- and norepinephrine-producing chromaffin cells. Therefore, we examined plasma catecholamine concentration and blood pressure in wild-type and pendrin-null mice under basal conditions and then after 5 and 20 min of immobilization stress. Under basal conditions, blood pressure was lower in the mutant than in the wild-type mice, although epinephrine and norepinephrine concentrations were similar. Catecholamine concentration and blood pressure increased markedly in both groups with stress. With 20 min of immobilization stress, epinephrine and norepinephrine concentrations increased more in pendrin-null than in wild-type mice, although stress produced a similar increase in blood pressure in both groups. We conclude that pendrin is expressed in the adrenal medulla, where it blunts stress-induced catecholamine release.
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Affiliation(s)
| | - Greti Aguilera
- Section on Endocrine Physiology, Developmental Endocrinology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Truyen D Pham
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Annie Y Park
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - William H Beierwaltes
- Hypertension and Vascular Research Division, Henry Ford Hospital and Wayne State School of Medicine, Detroit, Michigan
| | - Roy L Sutliff
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Atlanta Veterans Affairs Hospital, Atlanta, Georgia
| | - Jill W Verlander
- Department of Medicine, University of Florida, Gainesville, Florida
| | - Karel Pacak
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Adeboye O Osunkoya
- Department of Pathology, Emory University School of Medicine, Atlanta, Georgia
| | - Carla L Ellis
- Department of Pathology, Emory University School of Medicine, Atlanta, Georgia
| | - Young Hee Kim
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Gregory L Shipley
- Department of Integrative Biology and Pharmacology, University of Texas Medical School at Houston, Houston, Texas
| | - Brandi M Wynne
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Robert S Hoover
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Atlanta Veterans Affairs Hospital, Atlanta, Georgia; Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Shurjo K Sen
- Cardiovascular Disease Section, and National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Paul M Plotsky
- Department of Psychiatry, Emory University School of Medicine, Atlanta, Georgia; and
| | - Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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17
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Pech V, Wall SM, Nanami M, Bao HF, Kim YH, Lazo-Fernandez Y, Yue Q, Pham TD, Eaton DC, Verlander JW. Pendrin gene ablation alters ENaC subcellular distribution and open probability. Am J Physiol Renal Physiol 2015; 309:F154-63. [PMID: 25972513 DOI: 10.1152/ajprenal.00564.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 05/04/2015] [Indexed: 01/15/2023] Open
Abstract
The present study explored whether the intercalated cell Cl(-)/HCO3(-) exchanger pendrin modulates epithelial Na(+) channel (ENaC) function by changing channel open probability and/or channel density. To do so, we measured ENaC subunit subcellular distribution by immunohistochemistry, single channel recordings in split open cortical collecting ducts (CCDs), as well as transepithelial voltage and Na(+) absorption in CCDs from aldosterone-treated wild-type and pendrin-null mice. Because pendrin gene ablation reduced 70-kDa more than 85-kDa γ-ENaC band density, we asked if pendrin gene ablation interferes with ENaC cleavage. We observed that ENaC-cleaving protease application (trypsin) increased the lumen-negative transepithelial voltage in pendrin-null mice but not in wild-type mice, which raised the possibility that pendrin gene ablation blunts ENaC cleavage, thereby reducing open probability. In mice harboring wild-type ENaC, pendrin gene ablation reduced ENaC-mediated Na(+) absorption by reducing channel open probability as well as by reducing channel density through changes in subunit total protein abundance and subcellular distribution. Further experiments used mice with blunted ENaC endocytosis and degradation (Liddle's syndrome) to explore the significance of pendrin-dependent changes in ENaC open probability. In mouse models of Liddle's syndrome, pendrin gene ablation did not change ENaC subunit total protein abundance, subcellular distribution, or channel density, but markedly reduced channel open probability. We conclude that in mice harboring wild-type ENaC, pendrin modulates ENaC function through changes in subunit abundance, subcellular distribution, and channel open probability. In a mouse model of Liddle's syndrome, however, pendrin gene ablation reduces channel activity mainly through changes in open probability.
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Affiliation(s)
- Vladimir Pech
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | - Masayoshi Nanami
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Hui-Fang Bao
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | - Young Hee Kim
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | | | - Qiang Yue
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | - Truyen D Pham
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and
| | - Jill W Verlander
- Department of Medicine, University of Florida, Gainesville, Florida
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18
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Sakalli M, Pham TD, Lam KM, Yan H. A curvelet-based morphological segmentation of abdominal CT images. Annu Int Conf IEEE Eng Med Biol Soc 2015; 2014:5542-5. [PMID: 25571250 DOI: 10.1109/embc.2014.6944882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper presents a segmentation methodology of abdominal axial CT images. The aim of the study is to determine the location of mesenteric area from the axial images so the organs enclosed within can be localized precisely for diagnostic purposes. The challenge confronted here is that there is no a certain deterministic shape of abdominal organs. The methodology implemented here utilizes a curvelets stage followed by morphological image processing to achieve a contour emphasized segmentation from the gestalts of surrounding organs. This paper gives a detailed analysis of approach taken with the problems faced and a brief comparison wrt to other wavelet approaches.
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19
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Sutliff RL, Walp ER, Kim YH, Walker LA, El-Ali AM, Ma J, Bonsall R, Ramosevac S, Eaton DC, Verlander JW, Hansen L, Gleason RLJ, Pham TD, Hong S, Pech V, Wall SM. Contractile force is enhanced in Aortas from pendrin null mice due to stimulation of angiotensin II-dependent signaling. PLoS One 2014; 9:e105101. [PMID: 25148130 PMCID: PMC4141771 DOI: 10.1371/journal.pone.0105101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 07/20/2014] [Indexed: 11/19/2022] Open
Abstract
Pendrin is a Cl−/HCO3− exchanger expressed in the apical regions of renal intercalated cells. Following pendrin gene ablation, blood pressure falls, in part, from reduced renal NaCl absorption. We asked if pendrin is expressed in vascular tissue and if the lower blood pressure observed in pendrin null mice is accompanied by reduced vascular reactivity. Thus, the contractile responses to KCl and phenylephrine (PE) were examined in isometrically mounted thoracic aortas from wild-type and pendrin null mice. Although pendrin expression was not detected in the aorta, pendrin gene ablation changed contractile protein abundance and increased the maximal contractile response to PE when normalized to cross sectional area (CSA). However, the contractile sensitivity to this agent was unchanged. The increase in contractile force/cross sectional area observed in pendrin null mice was due to reduced cross sectional area of the aorta and not from increased contractile force per vessel. The pendrin-dependent increase in maximal contractile response was endothelium- and nitric oxide-independent and did not occur from changes in Ca2+ sensitivity or chronic changes in catecholamine production. However, application of 100 nM angiotensin II increased force/CSA more in aortas from pendrin null than from wild type mice. Moreover, angiotensin type 1 receptor inhibitor (candesartan) treatment in vivo eliminated the pendrin-dependent changes contractile protein abundance and changes in the contractile force/cross sectional area in response to PE. In conclusion, pendrin gene ablation increases aorta contractile force per cross sectional area in response to angiotensin II and PE due to stimulation of angiotensin type 1 receptor-dependent signaling. The angiotensin type 1 receptor-dependent increase in vascular reactivity may mitigate the fall in blood pressure observed with pendrin gene ablation.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Anion Transport Proteins/deficiency
- Anion Transport Proteins/genetics
- Aorta/drug effects
- Aorta/metabolism
- Aorta/pathology
- Calcium/metabolism
- Catecholamines/biosynthesis
- Dose-Response Relationship, Drug
- Gene Expression
- Kidney/metabolism
- Male
- Mice
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Nitric Oxide/metabolism
- Phenylephrine/pharmacology
- Potassium Chloride/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Angiotensin, Type 1/metabolism
- Signal Transduction/drug effects
- Sulfate Transporters
- Vasoconstriction/drug effects
- Vasoconstriction/genetics
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Roy L. Sutliff
- Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, United States of America
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Erik R. Walp
- Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, United States of America
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Young Hee Kim
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Lori A. Walker
- Departments of Medicine and Cardiology, University of Colorado Health Sciences Center, Aurora, Colorado, United States of America
| | - Alexander M. El-Ali
- Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, United States of America
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Jing Ma
- Atlanta Veterans Affairs Medical Center, Atlanta, Georgia, United States of America
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Robert Bonsall
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, Georgia, United States of America
| | - Semra Ramosevac
- Department of Physiology, Emory University, Atlanta, Georgia, United States of America
| | - Douglas C. Eaton
- Department of Physiology, Emory University, Atlanta, Georgia, United States of America
| | - Jill W. Verlander
- Department of Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Laura Hansen
- School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Rudolph L. Jr. Gleason
- School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Truyen D. Pham
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Seongun Hong
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Vladimir Pech
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
| | - Susan M. Wall
- Department of Medicine, Emory University, Atlanta, Georgia, United States of America
- Department of Physiology, Emory University, Atlanta, Georgia, United States of America
- * E-mail:
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20
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Zhang C, Sun C, Pham TD. Segmentation of clustered nuclei based on concave curve expansion. J Microsc 2013; 251:57-67. [PMID: 23692597 DOI: 10.1111/jmi.12043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 03/19/2013] [Indexed: 12/01/2022]
Abstract
Segmentation of nuclei from images of tissue sections is important for many biological and biomedical studies. Many existing image segmentation algorithms may lead to oversegmentation or undersegmentation for clustered nuclei images. In this paper, we proposed a new image segmentation algorithm based on concave curve expansion to correctly and accurately extract markers from the original images. Marker-controlled watershed is then used to segment the clustered nuclei. The algorithm was tested on both synthetic and real images and better results are achieved compared with some other state-of-the-art methods.
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Affiliation(s)
- C Zhang
- CSIRO Mathematics, Informatics and Statistics Division, Locked Bag 17, North Ryde, New South Wales 2113, Australia.
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21
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Pech V, Pham TD, Hong S, Weinstein AM, Spencer KB, Duke BJ, Walp E, Kim YH, Sutliff RL, Bao HF, Eaton DC, Wall SM. Pendrin modulates ENaC function by changing luminal HCO3-. J Am Soc Nephrol 2010; 21:1928-41. [PMID: 20966128 DOI: 10.1681/asn.2009121257] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The epithelial Na(+) channel, ENaC, and the Cl(-)/HCO(3)(-) exchanger, pendrin, mediate NaCl absorption within the cortical collecting duct and the connecting tubule. Although pendrin and ENaC localize to different cell types, ENaC subunit abundance and activity are lower in aldosterone-treated pendrin-null mice relative to wild-type mice. Because pendrin mediates HCO(3)(-) secretion, we asked if increasing distal delivery of HCO(3)(-) through a pendrin-independent mechanism "rescues" ENaC function in pendrin-null mice. We gave aldosterone and NaHCO(3) to increase pendrin-dependent HCO(3)(-) secretion within the connecting tubule and cortical collecting duct, or gave aldosterone and NaHCO(3) plus acetazolamide to increase luminal HCO(3)(-) concentration, [HCO(3)(-)], independent of pendrin. Following treatment with aldosterone and NaHCO(3), pendrin-null mice had lower urinary pH and [HCO(3)(-)] as well as lower renal ENaC abundance and function than wild-type mice. With the addition of acetazolamide, however, acid-base balance as well as ENaC subunit abundance and function was similar in pendrin-null and wild-type mice. We explored whether [HCO(3)(-)] directly alters ENaC abundance and function in cultured mouse principal cells (mpkCCD). Amiloride-sensitive current and ENaC abundance rose with increased [HCO(3)(-)] on the apical or the basolateral side, independent of the substituting anion. However, ENaC was more sensitive to changes in [HCO(3)(-)] on the basolateral side of the monolayer. Moreover, increasing [HCO(3)(-)] on the apical and basolateral side of Xenopus kidney cells increased both ENaC channel density and channel activity. We conclude that pendrin modulates ENaC abundance and function, at least in part by increasing luminal [HCO(3)(-)] and/or pH.
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Affiliation(s)
- Vladimir Pech
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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22
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Kim YH, Pham TD, Zheng W, Hong S, Baylis C, Pech V, Beierwaltes WH, Farley DB, Braverman LE, Verlander JW, Wall SM. Role of pendrin in iodide balance: going with the flow. Am J Physiol Renal Physiol 2009; 297:F1069-79. [PMID: 19605545 DOI: 10.1152/ajprenal.90581.2008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Pendrin is expressed in the apical regions of type B and non-A, non-B intercalated cells, where it mediates Cl(-) absorption and HCO3(-) secretion through apical Cl(-)/HCO3(-) exchange. Since pendrin is a robust I(-) transporter, we asked whether pendrin is upregulated with dietary I(-) restriction and whether it modulates I(-) balance. Thus I(-) balance was determined in pendrin null and in wild-type mice. Pendrin abundance was evaluated with immunoblots, immunohistochemistry, and immunogold cytochemistry with morphometric analysis. While pendrin abundance was unchanged when dietary I(-) intake was varied over the physiological range, I(-) balance differed in pendrin null and in wild-type mice. Serum I(-) was lower, while I(-) excretion was higher in pendrin null relative to wild-type mice, consistent with a role of pendrin in renal I(-) absorption. Increased H2O intake enhanced differences between wild-type and pendrin null mice in I(-) balance, suggesting that H2O intake modulates pendrin abundance. Raising water intake from approximately 4 to approximately 11 ml/day increased the ratio of B cell apical plasma membrane to cytoplasm pendrin label by 75%, although circulating renin, aldosterone, and serum osmolality were unchanged. Further studies asked whether H2O intake modulates pendrin through the action of AVP. We observed that H2O intake modulated pendrin abundance even when circulating vasopressin levels were clamped. We conclude that H2O intake modulates pendrin abundance, although not likely through a direct, type 2 vasopressin receptor-dependent mechanism. As water intake rises, pendrin becomes increasingly critical in the maintenance of Cl(-) and I(-) balance.
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Affiliation(s)
- Young Hee Kim
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
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23
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Sutliff RL, Walp ER, Bonsall R, Ramosevac S, Eaton DC, Kim YH, Pham TD, Wall SM. Pendrin gene ablation enhances vascular contractility. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.774.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Erik R. Walp
- MedicineEmory University School of MedicineDecaturGA
| | | | | | | | - Young Hee Kim
- MedicineEmory University School of MedicineAtlantaGA
| | | | - Susan M. Wall
- MedicineEmory University School of MedicineAtlantaGA
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24
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Abstract
We reported previously that angiotensin II (AngII) increases net Cl(-) absorption in mouse cortical collecting duct (CCD) by transcellular transport across type B intercalated cells (IC) via an H(+)-ATPase-and pendrin-dependent mechanism. Because intracellular trafficking regulates both pendrin and H(+)-ATPase, we hypothesized that AngII induces the subcellular redistribution of one or both of these exchangers. To answer this question, CCD from furosemide-treated mice were perfused in vitro, and the subcellular distributions of pendrin and the H(+)-ATPase were quantified using immunogold cytochemistry and morphometric analysis. Addition of AngII in vitro did not change the distribution of pendrin or H(+)-ATPase within type B IC but within type A IC increased the ratio of apical plasma membrane to cytoplasmic H(+)-ATPase three-fold. Moreover, CCDs secreted bicarbonate under basal conditions but absorbed bicarbonate in response to AngII. In summary, angiotensin II stimulates H(+) secretion into the lumen, which drives Cl(-) absorption mediated by apical Cl(-)/HCO(3)(-) exchange as well as generates more favorable electrochemical gradient for ENaC-mediated Na(+) absorption.
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Affiliation(s)
- Vladimír Pech
- Emory University School of Medicine, Renal Division, 1639 Pierce Drive, NE, WMB Room 338, Atlanta, GA 30322, USA.
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25
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Pech V, Zheng W, Pham TD, Verlander JW, Wall SM. Angiotensin II activates H+‐ATPase in type A intercalated cells in mouse cortical collecting duct. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1329-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Vladimir Pech
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
| | - Wencui Zheng
- Department of MedicineUniversity of Florida1600 SW Archer Rd., Rm. RB‐167GainesvilleFL32610
| | - Truyen D. Pham
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
| | - Jill W. Verlander
- Department of MedicineUniversity of Florida1600 SW Archer Rd., Rm. RB‐167GainesvilleFL32610
| | - Susan M. Wall
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
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26
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Pech V, Kim YH, Weinstein AM, Everett LA, Pham TD, Wall SM. Angiotensin II increases chloride absorption in the cortical collecting duct in mice through a pendrin-dependent mechanism. Am J Physiol Renal Physiol 2006; 292:F914-20. [PMID: 17077386 DOI: 10.1152/ajprenal.00361.2006] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pendrin (Slc26a4) localizes to type B and non-A, non-B intercalated cells in the distal convoluted tubule, the connecting tubule, and the cortical collecting duct (CCD), where it mediates apical Cl(-)/HCO(3)(-) exchange. The purpose of this study was to determine whether angiotensin II increases transepithelial net chloride transport, J(Cl), in mouse CCD through a pendrin-dependent mechanism. J(Cl) and transepithelial voltage, V(T), were measured in CCDs perfused in vitro from wild-type and Slc26a4 null mice ingesting a NaCl-replete diet or a NaCl-replete diet and furosemide. In CCDs from wild-type mice ingesting a NaCl-replete diet, V(T) and J(Cl) were not different from zero either in the presence or absence of angiotensin II (10(-8) M) in the bath. Thus further experiments employed mice given the high-NaCl diet and furosemide to upregulate renal pendrin expression. CCDs from furosemide-treated wild-type mice had a lumen-negative V(T) and absorbed Cl(-). With angiotensin II in the bath, Cl(-) absorption doubled although V(T) did not become more lumen negative. In contrast, in CCDs from furosemide-treated Slc26a4 null mice, Cl(-) secretion and a V(T) of approximately 0 were observed, neither of which changed with angiotensin II application. Inhibiting ENaC with benzamil abolished V(T) although J(Cl) fell only approximately 50%. Thus substantial Cl(-) absorption is observed in the absence of an electromotive force. Attenuating apical anion exchange with the peritubular application of the H(+)-ATPase inhibitor bafilomycin abolished benzamil-insensitive Cl(-) absorption. In conclusion, angiotensin II increases transcellular Cl(-) absorption in the CCD through a pendrin- and H(+)-ATPase-dependent process.
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Affiliation(s)
- Vladimír Pech
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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27
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Pech V, Zheng W, Pham TD, Verlander JW, Wall SM. Angiotensin II increases chloride absorption in the cortical collecting duct in mice by a pendrin‐dependent mechanism. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.a1225-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Vladimir Pech
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
| | - Wencui Zheng
- Department of MedicineUniversity of Florida1600 SW Archer Rd., Room RB‐167GainesvilleFL32610
| | - Truyen D Pham
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
| | - Jill W Verlander
- Department of MedicineUniversity of Florida1600 SW Archer Rd., Room RB‐167GainesvilleFL32610
| | - Susan M Wall
- Renal DivisionEmory University1639 Pierce Dr., WMB, Rm. 338AtlantaGA30322
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28
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Li ZS, Pham TD, Tamir H, Chen JJ, Gershon MD. Enteric dopaminergic neurons: definition, developmental lineage, and effects of extrinsic denervation. J Neurosci 2004; 24:1330-9. [PMID: 14960604 PMCID: PMC6730344 DOI: 10.1523/jneurosci.3982-03.2004] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Revised: 11/20/2003] [Accepted: 12/02/2003] [Indexed: 11/21/2022] Open
Abstract
The existence of enteric dopaminergic neurons has been suspected; however, the innervation of the gut by sympathetic nerves, in which dopamine (DA) is the norepinephrine precursor, complicates analyses of enteric DA. We now report that transcripts encoding tyrosine hydroxylase (TH) and the DA transporter (DAT) are present in the murine bowel (small intestine > stomach or colon; proximal colon > distal colon). Because sympathetic neurons are extrinsic, transcripts encoding TH and DAT in the bowel are probably derived from intrinsic neurons. TH protein was demonstrated immunocytochemically in neuronal perikarya (submucosal >> myenteric plexus; small intestine > stomach or colon). TH, DA, and DAT immunoreactivities were coincident in subsets of neurons (submucosal > myenteric) in guinea pig and mouse intestines in situ and in cultured guinea pig enteric ganglia. Surgical ablation of sympathetic nerves by extrinsic denervation of loops of the bowel did not affect DAT immunoreactivity but actually increased numbers of TH-immunoreactive neurons, expression of mRNA encoding TH and DAT, and enteric DOPAC (the specific dopamine metabolite). The fetal gut contains transiently catecholaminergic (TC) cells. TC cells are the proliferating crest-derived precursors of mature neurons that are not catecholaminergic and, thus, disappear after embryonic day (E) 14 (mouse) or E15 (rat). TC cells appear early in ontogeny, and their development/survival is dependent on mash-1 gene expression. In contrast, the intrinsic TH-expressing neurons of the murine bowel appear late (perinatally) and are mash-1 independent. We conclude that the enteric nervous system contains intrinsic dopaminergic neurons that arise from a mash-1-independent lineage of noncatecholaminergic precursors.
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Affiliation(s)
- Z S Li
- Department of Anatomy and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA.
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29
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Chalazonitis A, Pham TD, Rothman TP, DiStefano PS, Bothwell M, Blair-Flynn J, Tessarollo L, Gershon MD. Neurotrophin-3 is required for the survival-differentiation of subsets of developing enteric neurons. J Neurosci 2001; 21:5620-36. [PMID: 11466433 PMCID: PMC6762643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2001] [Revised: 05/03/2001] [Accepted: 05/03/2001] [Indexed: 02/20/2023] Open
Abstract
Neurotrophin-3 (NT-3) promotes enteric neuronal development in vitro; nevertheless, an enteric nervous system (ENS) is present in mice lacking NT-3 or TrkC. We thus analyzed the physiological significance of NT-3 in ENS development. Subsets of neurons developing in vitro in response to NT-3 became NT-3 dependent; NT-3 withdrawal led to apoptosis, selectively in TrkC-expressing neurons. Antibodies to NT-3, which blocked the developmental response of enteric crest-derived cells to exogenous NT-3, did not inhibit neuronal development in cultures of isolated crest-derived cells but did so in mixed cultures of crest- and non-neural crest-derived cells; therefore, the endogenous NT-3 that supports enteric neuronal development is probably obtained from noncrest-derived mesenchymal cells. In mature animals, retrograde transport of (125)I-NT-3, injected into the mucosa, labeled neurons in ganglia of the submucosal but not myenteric plexus; injections of (125)I-NT-3 into myenteric ganglia, the tertiary plexus, and muscle, labeled neurons in underlying submucosal and distant myenteric ganglia. The labeling pattern suggests that NT-3-dependent submucosal neurons may be intrinsic primary afferent and/or secretomotor, whereas NT-3-dependent myenteric neurons innervate other myenteric ganglia and/or the longitudinal muscle. Myenteric neurons were increased in number and size in transgenic mice that overexpress NT-3 directed to myenteric ganglia by the promoter for dopamine beta-hydroxylase. The numbers of neurons were regionally reduced in both plexuses in mice lacking NT-3 or TrkC. A neuropoietic cytokine (CNTF) interacted with NT-3 in vitro, and if applied sequentially, compensated for NT-3 withdrawal. These observations indicate that NT-3 is required for the normal development of the ENS.
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Affiliation(s)
- A Chalazonitis
- Department of Anatomy and Cell Biology, Columbia University, New York, New York 10032, USA.
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Le Quan Sang KH, Le Feuvre C, Brunet A, Pham TD, Metzger JP, Vacheron A, Devynck MA. Influence of SIN-1 on platelet Ca2+ handling in patients with suspected coronary artery disease: ex vivo and in vitro studies. Thromb Haemost 2000; 83:752-8. [PMID: 10823274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The 3-morpholinosydnonimine (SIN-1) generates both nitric oxide (NO) and superoxide anion (O2-). It elicits dose-dependent vasodilation in vivo, in spite of the opposite effects of its breakdown products on vascular tone and platelet aggregation. This study was designed to investigate the influence of intravenous SIN-1 injection on platelet Ca2+ handling in patients undergoing coronary angiography. SIN-1 administration reduced cytosolic [Ca2+] in unstimulated platelets by decreasing Ca2+ influx. It attenuated Ca2+ mobilization from internal stores evoked by thrombin or thapsigargin. In vitro studies were used as an approach to investigate how simultaneous productions of NO and O2- from SIN-1 modify thrombin- or thapsigargin-induced platelet Ca2+ mobilization. Superoxide dismutase, the O2- scavenger, enhanced the capacity of SIN-1 to inhibit Ca2+ mobilization but catalase had no effect. This suggests that the effects of SIN-1 on platelet Ca2+ handling resemble those of NO, but are modulated by simultaneous O2- release, independently of H2O2 formation.
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Affiliation(s)
- K H Le Quan Sang
- Pharmacologie, CNRS UMR 8604, Faculté de Médecine Necker-Enfants Malades, Université René Descartes, Paris, France.
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Millanvoye-Van Brussel E, David-Dufilho M, Pham TD, Iouzalen L, Aude Devynck M. Regulation of arachidonic acid release by calcium influx in human endothelial cells. J Vasc Res 1999; 36:235-44. [PMID: 10393510 DOI: 10.1159/000025647] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In response to stimuli, endothelial cells release arachidonic acid, a lipid precursor of various vasoactive substances. We have investigated the relationships between cytosolic Ca2+ movements and arachidonic acid release in human umbilical vein endothelial cells. Histamine, a receptor-dependent agonist, and thapsigargin, a specific inhibitor of sarco-/endoplasmic Ca2+ pumps, time- and dose-dependently increased the release of [1-14C]-arachidonic acid. This release was inhibited by AACOCF3, a selective inhibitor of cytosolic phospholipase A2 (PLA2). In the absence of Ca2+ influx, arachidonic acid release was suppressed in both histamine- and thapsigargin-stimulated cells, despite marked elevations of cytosolic Ca2+ concentration ([Ca2+]i). In the presence of Ca2+ influx, arachidonic acid release was reduced in cells treated with BAPTA, an intracellular Ca2+ buffer, or with SK&F 96365, a receptor-operated Ca2+ channel blocker. Arachidonic acid release was analyzed as a function of the two successive phases of Ca2+ response to stimulation: Ca2+ peak and plateau phase, reflecting Ca2+ mobilization from internal stores and Ca2+ influx, respectively. The amount of arachidonic acid released was directly related to [Ca2+]i values measured at the influx phase with a 80 nM [Ca2+]i threshold, similar to that reported for PLA2 translocation. This suggests that Ca2+ entry from the extracellular space is essential for activating cytosolic PLA2 in human endothelial cells.
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Abstract
A reverse transcriptase polymerase chain (RT-PCR) assay was developed to detect avian leukosis retrovirus (ALV) in egg albumen. Eggs of Single Comb White Leghorns were from a commercial breeder (stock F) and from a pathogen-free flock (stock N). RT-PCR was undertaken on isolated RNA from 20 unfertilized egg samples using seven sets of primers that correspond to the ALV gp85 envelope glycoprotein which determines the ALV subgroup classification. An ELISA assay for ALV gs antigen of egg albumen was positive for all stock F birds tested and negative for all stock N birds. Virus isolation was undertaken by inoculating egg albumen, feather pulp, or blood from five stock F chickens onto cultures of chicken embryo fibroblasts (C/E). IFA analysis of the inoculated C/E cultures indicated that all stock F birds tested contained infectious ALV. For the virus-positive stock F chickens, RT-PCR analyses using primers designed to detect all ALV subgroups detected ALV in 15/15 (100%) egg albumen samples, while primers designed to detect subgroup A ALV were positive for 12/15 (80%) egg albumen samples. RT-PCR products were not detected from five egg albumen samples from five stock N chickens by any primer sets. Direct sequencing using primers specific for subgroup A ALV verified the viral subgroup in the RT-PCR amplification products. The combined use of RT-PCR and direct sequencing of the RT-PCR product provides a new approach for identifying ALV-infected poultry.
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Affiliation(s)
- T D Pham
- Department of Biostatistics and Epidemiology, Tulane University Medical Center, New Orleans, LA 70112, USA
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Day NP, Pham TD, Phan TL, Dinh XS, Pham PL, Ly VC, Tran TH, Nguyen TH, Bethell DB, Nguyan HP, Tran TH, White NJ. Clearance kinetics of parasites and pigment-containing leukocytes in severe malaria. Blood 1996; 88:4694-700. [PMID: 8977263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In tropical areas, where unsupervised use of antimalarial drugs is common, patients with an illness consistent clinically with severe malaria but with negative blood smears pose a management dilemma. Malaria pigment is evident in peripheral blood leukocytes in greater than 90% of patients with severe malaria. To characterize the clearance kinetics of parasitized erythrocytes and malaria pigment-containing leukocytes, sequential peripheral blood and intradermal smears were assessed in 27 adult Vietnamese patients with severe falciparum malaria. The clearance of parasitized erythrocytes and pigment-containing monocytes (PCMs) followed first order kinetics. The elimination of pigment-containing neutrophils (PCNs) was first order initially, but deviated from this when counts were low. Clearance of peripheral blood PCMs (median clearance time, 216 hours; range, 84 to 492 hours) was significantly slower than that of parasitized erythrocytes (median, 96 hours; range, 36 to 168 hours) or PCNs (median, 72 hours; range, 0 to 168 hours; P < .0001). Intradermal PCM clearance times were the longest of all (median, 12 days; range, 6 to 23 days; significantly longer than peripheral blood PCM clearance, P < .001). Twenty-one (88%) patients still had signs, symptoms, or laboratory features of severe malaria after parasite clearance but before phagocyte pigment clearance. Sixteen of the 23 surviving patients (70%; 95% confidence interval, 50% to 87%) still had intraleukocytic malaria pigment on peripheral blood films 72 hours after parasite clearance. Thus, by determining the distribution of malaria pigment in peripheral blood and intradermal phagocytes, the time since effective antimalarial treatment started can be estimated. Microscopy for intraleukocytic pigment is valuable in the differential diagnosis of severe febrile illnesses in malarious areas where uncontrolled use of antimalarial drugs is widespread.
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Affiliation(s)
- N P Day
- Centre for Tropical Diseases, Cho Quan Hospital, Ho Chi Minh City, Vietnam
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Blaugrund E, Pham TD, Tennyson VM, Lo L, Sommer L, Anderson DJ, Gershon MD. Distinct subpopulations of enteric neuronal progenitors defined by time of development, sympathoadrenal lineage markers and Mash-1-dependence. Development 1996; 122:309-20. [PMID: 8565843 DOI: 10.1242/dev.122.1.309] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Enteric and sympathetic neurons have previously been proposed to be lineally related. We present independent lines of evidence that suggest that enteric neurons arise from at least two lineages, only one of which expresses markers in common with sympathoadrenal cells. In the rat, sympathoadrenal markers are expressed, in the same order as in sympathetic neurons, by a subset of enteric neuronal precursors, which also transiently express tyrosine hydroxylase. If this precursor pool is eliminated in vitro by complement-mediated lysis, enteric neurons continue to develop; however, none of these are serotonergic. In the mouse, the Mash-1−/− mutation, which eliminates sympathetic neurons, also prevents the development of enteric serotonergic neurons. Other enteric neuronal populations, however, including those that contain calcitonin gene related peptide are present. Enteric tyrosine hydroxylase-containing cells co-express Mash-1 and are eliminated by the Mash-1−/− mutation, consistent with the idea that in the mouse, as in the rat, these precursors generate serotonergic neurons. Serotonergic neurons are generated early in development, while calcitonin gene related peptide-containing enteric neurons are generated much later. These data suggest that enteric neurons are derived from at least two progenitor lineages. One transiently expresses sympathoadrenal markers, is Mash-1-dependent, and generates early-born enteric neurons, some of which are serotonergic. The other is Mash-1-independent, does not express sympathoadrenal markers, and generates late-born enteric neurons, some of which contain calcitonin gene related peptide.
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Affiliation(s)
- E Blaugrund
- Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Abstract
The hypothesis was tested that developing enteric neurons withdraw from the cell cycle in a sequence related to their phenotype. The birthdays of immunocytochemically identified myenteric and submucosal neurons were determined in the murine duodenum and jejunum. [3H]thymidine ([3H]TdR) was injected into timed pregnant mice or pups at 4-8 hour intervals over a 24 hour period. Pups were killed on postnatal day 30 (P30). [3H]TdR incorporation was detected by radioautography in enteric neurons, which were phenotypically identified by the simultaneous detection of the immunoreactivities of 5-hydroxytryptamine (5-HT), choline acetyl transferase (ChAT), neuropeptide Y (NPY), enkephalin (ENK), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP). The dates of the earliest withdrawal from the cell cycle of neurons containing these markers were determined, as well as the length of time during which the identified neurons continued to be born, and the date on which their rate of birth was maximal. The birthdates of myenteric neurons that contained 5-HT (E8-E14, peak at E10) or ChAT (E8-E15, peak at E12) tended to be earlier than those that contained ENK (E10-E18, peak at E14), NPY (E10-E18, peak at E15), VIP (E10-P5, peak at E15), or CGRP (E10-P3, peak at E17). For any given immunocytochemically defined neuronal phenotype, submucosal neurons tended to be born later than their myenteric counterparts and submucosal neurons that contained neuropeptides were born later than those that contained only ChAT immunoreactivity. The day (E8) on which the first 5-HT- and ChAT-immunoreactive neurons became postmitotic is earlier than the day (E9) on which the colonization of the bowel by crest-derived cells has been detected. The population of neural precursors that colonizes the gut, therefore, is heterogeneous; many cells are proliferating, but a specific subset, which will ultimately give rise to serotoninergic or cholinergic neurons, is already postmitotic. Neurons continued to be born throughout fetal life and even after birth. Consequently, terminally differentiated neurons coexist in the developing enteric nervous system with dividing neural precursor cells. This observation is consistent with the idea that early developing neurons could affect the development of enteric neural precursors; moreover, they also demonstrate that it is possible to add neurons to the enteric plexuses even after the neural circuits on which the bowel depends have become functional.
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Affiliation(s)
- T D Pham
- Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York 10032
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Stanescu V, Chaminade F, Pham TD. Immunological detection of the EGF-like domain of the core proteins of large proteoglycans from human and baboon cartilage. Connect Tissue Res 1991; 26:283-93. [PMID: 1721018 DOI: 10.3109/03008209109152445] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Recent data from the literature have shown that cDNA clones for the carboxyterminal domain of the core protein of large proteoglycan monomers from human cartilage contain an EGF-like domain, which appears to undergo alternative splicing. In the present study we have found that articular proteoglycans from human and baboon separated on agarose flat-bed gels and blotted onto nitrocellulose react with a rabbit antiserum to mouse EGF. In addition both forms of the proteoglycans (band I and band II) seen on these gels are reactive. Reactivity is seen with proteoglycans extracted from human articular cartilage of various ages (fetal, newborn, young and aged) and with proteoglycans extracted from cartilage of thanatophoric dysplasia and homozygous achondroplasia. Reactivity is dependent on prior digestion of the nitrocellulose blot with Chase ABC, suggesting masking of epitope by chondroitin sulfate. Reactivity of the EGF antiserum with cartilage proteoglycan core protein was also demonstrated in an ELISA system with core protein as coating antigen. The reactivity appears to reside in a tryptic peptide generated from Chase/keratanase digested core protein. The immunoreactive species migrates as a 68 KDa species on gradient gels. Immunological detection and quantitative analysis of the EGF-like domain could be useful for analysis of various proteoglycan samples.
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Affiliation(s)
- V Stanescu
- URA.584-CNRS, Hôpital des Enfants-Malades, Paris, France
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Payette RF, Tennyson VM, Pomeranz HD, Pham TD, Rothman TP, Gershon MD. Accumulation of components of basal laminae: association with the failure of neural crest cells to colonize the presumptive aganglionic bowel of ls/ls mutant mice. Dev Biol 1988; 125:341-60. [PMID: 3338619 DOI: 10.1016/0012-1606(88)90217-5] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Aganglionosis occurs in the terminal colon of the ls/ls mouse because an intrinsic defect of the presumptive aganglionic tissue prevents the entry and colonization of this portion of the bowel by migrating neural crest cells. The current study was undertaken to determine if abnormalities of the extracellular matrix could be identified in this segment that might account for migratory failure. Since basal laminae of the muscularis mucosa are overproduced in the aganglionic segment of adult ls/ls mice, we examined components of basal laminae in fetal gut from Day E 11 to Day E 16 of gestation. This period spans the time of enteric ganglion formation. Laminin and collagen type IV were studied by immunocytochemistry and proteoglycans by staining glycosaminoglycans with Alcian blue. Abnormalities of each of these components occur during development of the presumptive aganglionic bowel in the ls/ls mouse and could be detected as early as Day E 11. These defects consist mainly of an overabundance of these materials, both in defined basal laminae and throughout the extracellular space of the mesenchyme. Electron microscopic observations in the presumptive aganglionic ls/ls colon revealed a thickening of basal laminae and exceptionally wide intercellular spaces between smooth muscle myoblasts that contained an irregular fibrillar material, consisting of 4.5- to 6.0-nm filaments associated with 14- to 20-nm granules. Fibrillar and flocculant material was continuous with formed basal laminae, and was concentrated in the same areas found to have an overabundance of laminin immunoreactivity. These observations indicate that there is an accumulation of extracellular matrix material, including components of basal laminae, that (i) precedes the formation of enteric ganglia, (ii) is in the path through which enteric neural precursors from the crest would have to migrate, and (iii) is limited to the aganglionic and hypoganglionic ls/ls bowel. These data are consistent with the hypothesis that components of basal laminae contribute to the inability of crest cells to colonize the terminal bowel of ls/ls mice.
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Affiliation(s)
- R F Payette
- Department of Anatomy and Cell Biology, College of Physicians and Surgeons of Columbia University, New York, New York 10032
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Stanescu V, Pham TD. Preparative electrophoresis on agarose submerged gels of two aggregating proteoglycan monomers from articular cartilage. Prep Biochem 1987; 17:229-38. [PMID: 3628196 DOI: 10.1080/00327488708062491] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Analytical electrophoresis on polyacrylamide-agarose gels of aggregating proteoglycan monomers from baboon articular cartilage produces two distinct bands, corresponding to two different aggregating monomer populations. A preparative electrophoresis procedure is described for isolating the two monomers. Proteoglycans were extracted from young baboon articular cartilage in 4 M guanidinium chloride containing proteolysis inhibitors and aggregated after hyaluronic acid addition. The aggregates were separated from non-aggregated proteoglycans by isopycnic centrifugation, followed by gel chromatography on Sepharose CL-2B. The monomers of the aggregates were obtained by isopycnic centrifugation under dissociative conditions. Two monomers were separated by preparative electrophoresis on 0.8 % agarose submerged gels. Approximately 60 % of the proteoglycans were recovered from the gel using a freeze-squeeze procedure. Aliquots of the separated monomers gave single bands when submitted to analytical polyacrylamide-agarose gel electrophoresis. Their migration and appearance were similar to that of the two bands present in the non separated preparation of monomers.
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Payette RF, Tennyson VM, Pham TD, Mawe GM, Pomeranz HD, Rothman TP, Gershon MD. Origin and morphology of nerve fibers in the aganglionic colon of the lethal spotted (ls/ls) mutant mouse. J Comp Neurol 1987; 257:237-52. [PMID: 3571527 DOI: 10.1002/cne.902570209] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The lethal spotted mutant mouse (ls/ls) develops congenital megacolon because of the absence of ganglia in the terminal colon. This aganglionosis results from a failure of neural crest cells to colonize this area during fetal life. We have postulated that the microenvironment of the aganglionic segment of bowel is abnormal. Our hypothesis suggests that this abnormal enteric microenvironment fosters the sprouting of neuritic processes. We further propose that neural and glial precursors cease to migrate once they have extended their definitive processes. As a result, the area distal to the site where neurite extension is favored does not become colonized by neural or glial precursors. A prediction of this hypothesis is that the aganglionic tissue should be innervated by axons from neurons located both in the more proximal ganglionated bowel and in ganglia located outside the gut. Neurons and their processes in control and ls/ls terminal gut were located by the histochemical demonstration of acetylcholinesterase (AChE) activity and their structure was classified as intrinsic (enteric) or extrinsic in type by electron microscopy. In ls/ls mice the submucosal plexus was much more severely affected than the myenteric plexus. No submucosal ganglia were found within 30 mm of the anus. In contrast, myenteric ganglia extended to within 4 mm of the anus on the mesenteric side of the gut and to within 15 mm on the antimesenteric side. Rostral to the areas that were absolutely aganglionic, both plexuses were hypoganglionic, especially the submucosal plexus, which was hypoganglionic throughout the entire colon. Both the aganglionic and caudal hypoganglionic zones of the ls/ls bowel were penetrated by large nerve trunks that had the ultrastructural characteristics of extra-enteric peripheral nerve. Unusual ganglia, outside the enteric musculature in the adventitia of the colon, were connected to these trunks. The location of the cell bodies of origin of the nerve fibers in the terminal colon of control mice and in the aganglionic segment of the bowel in ls/ls mice was determined by following the retrograde transport of tracers injected as close as possible to the anus. An extrinsic innervation originating from the inferior mesenteric ganglion and dorsal root ganglia (L6-S1) was found in both types of animal. In control but not ls/ls mice retrograde labeling was also observed in the sacral parasympathetic nucleus of the spinal cord. In addition, neuritic processes were traced to neurons in myenteric ganglia. In control mice, these labeled neurons were present in ganglia within the injection site as well as in bowel rostral and caudal to it.(ABSTRACT TRUNCATED AT 400 WORDS)
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Tennyson VM, Pham TD, Rothman TP, Gershon MD. Abnormalities of smooth muscle, basal laminae, and nerves in the aganglionic segments of the bowel of lethal spotted mutant mice. Anat Rec (Hoboken) 1986; 215:267-81. [PMID: 3740466 DOI: 10.1002/ar.1092150310] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The terminal portion of the bowel of the lethal spotted mutant mouse (ls/ls) lacks an enteric nervous system due to the failure of neural crest precursors to colonize this region during embryonic life. As a result, the mouse develops congenital megacolon. We have postulated that the defect occurs because the microenvironment of the aganglionic segment is segmentally abnormal and does not permit the migration and/or survival of the enteric neural or glial precursors in the affected zone. We have examined the terminal segment of adult ls/ls and control mice by light and electron microscopy to determine if the defect is associated with identifiable structural abnormalities that persist to maturity. A striking abnormality is an overgrowth of the muscularis mucosa in the adult ls/ls mouse, particularly in the outer longitudinal layer. Electron microscopy also reveals an extensive thickening of the basal lamina around smooth muscle cells. In addition, nerves that are derived from fibers that are extrinsic to this area are abnormal. Large bundles of nerve fibers, some of which contain myelinated axons, large-caliber unmyelinated axons, and abundant collagen, are prominent in the intermuscular region of the aganglionic segments and often reach into the submucosa. The supporting cells of the unmyelinated and myelinated nerves in the aganglionic segment have voluminous perineural cytoplasm typical of immature Schwann cells. They also exhibit intermediate filaments in their cytoplasm. Otherwise they have the typical morphology of peripheral Schwann cells, rather than enteric glia, including individual ensheathment of axons and a surrounding basal lamina. We suggest that the extracellular matrix and/or cells of mesenchymal origin of the terminal bowel of the ls/ls mouse may prevent the ingrowth of the normal precursors of the glia as well as neurons of the enteric nervous system, but may permit or even encourage the ingrowth of abnormal numbers of extrinsic axons.
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Stanescu V, Pham TD. Gel electrophoresis of proteoglycan monomers of baboon articular cartilage separated by zonal rate centrifugation in sucrose gradients. Connect Tissue Res 1986; 14:169-77. [PMID: 2938876 DOI: 10.3109/03008208609014257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Proteoglycan monomers from articular cartilage of young baboons and of a baboon foetus were submitted to zonal rate centrifugation in sucrose gradients. The peaks obtained were analyzed by gel electrophoresis on polyacrylamide-agarose gels. The proteoglycan monomers corresponding to the bands obtained by gel-electrophoresis of unfractionated proteoglycans were separated in the gradients and the sedimentation distance correlated with the electrophoretic mobility.
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Fenoglio JJ, Pham TD, Harken AH, Horowitz LN, Josephson ME, Wit AL. Recurrent sustained ventricular tachycardia: structure and ultrastructure of subendocardial regions in which tachycardia originates. Circulation 1983; 68:518-33. [PMID: 6223722 DOI: 10.1161/01.cir.68.3.518] [Citation(s) in RCA: 212] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Surgical resection of the endocardium and subendocardium often abolishes chronic recurrent sustained ventricular tachycardia in patients with healed myocardial infarcts or ventricular aneurysms, presumably by interrupting the reentrant pathway. To define the morphologic characteristics of cells in the reentrant pathway, we studied the histology and ultrastructure of the endocardial resections of 23 patients who underwent this procedure. Bundles of apparently viable myocardial fibers embedded in dense fibrous tissue were identified throughout the endocardial resections from all patients. These bundles of cells were separated from one another by fibrous tissue but extended uninterrupted to the margins of the surgical resection. In 14 patients Purkinje fibers were identified beneath the thickened endocardium whereas the remaining bundles were composed of ventricular muscle. The Purkinje fibers appeared to have normal ultrastructure and ventricular cells with both normal and abnormal ultrastructures were present. The abnormal muscle cells were characterized by loss of contractile elements, aggregates of dilated sarcoplasmic reticulum, and osmiophilic dense bodies. The sarcolemma was intact and the nuclear chromatin was evenly dispersed suggesting that these cells were still viable. The abnormal structure and arrangement of the surviving cardiac fibers in the endocardium may cause the abnormal electrophysiologic function that results in ventricular tachycardia.
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Pham TD, Kaplan KL, Butler VP. Immunoelectron microscopic localization of platelet factor 4 and fibrinogen in the granules of human platelets. J Histochem Cytochem 1983; 31:905-10. [PMID: 6343481 DOI: 10.1177/31.7.6343481] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
To determine the storage site of platelet fibrinogen and of platelet factor 4 (PF4) in human platelets by immunoelectron microscopic techniques, washed human platelets were briefly exposed to Karnovsky's fixative and embedded in water-soluble Durcupan. Thin sections of platelets were exposed to Fab fragments of rabbit anti-human fibrinogen or of goat anti-human PF4, followed by a peroxidase conjugate of Fab fragments of antibodies to rabbit immunoglobulin (Ig) G or to goat IgG. The technique enabled preservation of the antigenic determinants of the platelet proteins, accessibility of Fab fragments to the platelet proteins, and maintenance of the ultrastructural integrity of the platelets. Using this approach, it was directly demonstrated that platelet fibrinogen and PF4 are stored in the alpha-granules of human platelets.
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Mary-Rabine L, Albert A, Pham TD, Hordof A, Fenoglio JJ, Malm JR, Rosen MR. The relationship of human atrial cellular electrophysiology to clinical function and ultrastructure. Circ Res 1983; 52:188-99. [PMID: 6218936 DOI: 10.1161/01.res.52.2.188] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Although previous studies have described the electrophysiological and ultrastructural characteristics of human cardiac fibers, no attempt has been made as yet to describe quantitatively the relationship between the ultrastructural and cellular electrophysiological derangements occurring with cardiac disease, and their clinical manifestations. In this study, we used standard microelectrode techniques to record the action potential characteristics of human atrial fibers obtained during cardiac surgery and correlated the electrophysiological parameters with clinical and ultrastructural data. Ultrastructure was studied by optical and electron microscopy. We found a multiple linear regression among maximum diastolic potential, atrial size and pressure, P wave duration and ultrastructure changes. Proliferations of Z band material, widening of intercalated discs, and degenerative changes were quantified and correlated with electrophysiological and clinical data. These studies emphasize the relationship between hemodynamic anomalies and resultant changes in both human atrial fiber structure and electrical function. Finally, the likelihood of occurrence of arrhythmias can be predicted using the analytic method described.
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Boyden PA, Tilley LP, Pham TD, Liu SK, Fenoglic JJ, Wit AL. Effects of left atrial enlargement on atrial transmembrane potentials and structure in dogs with mitral valve fibrosis. Am J Cardiol 1982; 49:1896-908. [PMID: 6211082 DOI: 10.1016/0002-9149(82)90208-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effects of left atrial enlargement on atrial cell electrophysiology and structure were studied in dogs with mitral valve fibrosis. Thirteen dogs (Groups I) had left atrial enlargement and intermittent atrial arrhythmias; 10 dogs (Group II) had left atrial enlargement and chronic atrial fibrillation. The resting and action potentials of cells in isolated preparations from the enlarged left atrium were found not to differ from those in the nonenlarged right atrium or in the atrium of control dogs. The resting and action potentials of cells in Group II atria did not differ significantly from those in Group I atria. Some cells (15 percent of the total studied) in the atria of dogs in Groups I and II were inexcitable, but either superfusion with acetylcholine or norepinephrine restored excitability. The structural studies showed that the left atrium of the dogs in Groups I and II had a reduced number of muscle cell layers spanning the wall with an unusually large amount of connective tissue between greatly hypertrophied cells. Very few degenerating cells were seen. Dramatic abnormalities of cell electrophysiology may not be involved in the genesis of arrhythmias in the enlarged canine atrium, and the altered morphologic features of the atrium in these dogs may be important in the genesis of persistent atrial arrhythmias.
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Abstract
We studied with ultrastructure techniques portions of right atrium resected at operation from 12 patients with chronic rheumatic heart disease and 6 patients with non-rheumatic valvular heart disease. The right atrial pressures, duration of symptoms and age of the patients were comparable in both groups. Ten of the 12 rheumatic and 4 of the 6 non-rheumatic patients had atrial fibrillation. In the 12 rheumatic patients we found severe interstitial fibrosis, extensive cellular degeneration (17% of cells studied) and marked cellular hypertrophy (average cell diameter 16 micrometers). The six non-rheumatic patients showed evidence of cellular hypertrophy (average cell diameter 15 micrometers) but minimal interstitial fibrosis or cellular degeneration. The degenerative changes in the rheumatic group did not correlate with the degree of hypertrophy or the extent of the hemodynamic alterations. Atrial fibrillation, present in both rheumatic and non-rheumatic patients, did not correlate with the presence of cellular degeneration. We conclude that the structural changes in atria of patients with chronic rheumatic heart disease may be part of the rheumatic process and are not entirely secondary to altered hemodynamics.
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Fenoglio JJ, Pham TD, Hordof A, Edie RN, Wit AL. Right atrial ultrastructure in congenital heart disease. II. Atrial septal defect: effects of volume overload. Am J Cardiol 1979; 43:820-7. [PMID: 425920 DOI: 10.1016/0002-9149(79)90084-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Portions of operatively resected right atrium from 15 patients with atrial septal defect were studied ultrastructurally to determine whether the cell hypertrophy in the right atrium of patients with increased right atrial blood flow and increased right atrial pressure is caused by the increased blood flow. In 12 patients with normal right atrial mean pressure but increased right atrial blood flow the atrium was dilated but no atrial arrhythmias were noted clinically. Ultrastructurally, the atrial myocardial cells in these patients were normal, measuring 6 to 10 mu in diameter, and there was no evidence of cell hypertrophy or degeneration. The remaining three patients had elevated right atrial mean pressure and increased right atrial blood flow. Ultrastructurally, the atrial myocardial cells in all three patients were hypertrophied, and two patients had evidence of focal cell degeneration; the atrium was markedly dilated, but atrial arrhythmias were not noted. The lack of cell hypertrophy in the right atrium of the 12 patients with increased blood flow but normal mean pressure suggests that in congenital heart disease volume overload alone does not lead to cell hypertrophy of the right atrial myocardium.
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Pham TD, Wit AL, Hordof AJ, Malm JR, Fenoglio JJ. Right atrial ultrastructure in congenital heart disease. I. Comparison of ventricular septal defect and endocardial cushion defect. Am J Cardiol 1978; 42:973-82. [PMID: 569433 DOI: 10.1016/0002-9149(78)90684-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ultrastructural studies were performed on portions of the operatively resected right atrium from six patients with a ventricular septal defect and six patients with an endocardial cushion defect. The six patients with a ventricular septal defect had normal right atrial mean pressure and no evidence of right atrial volume overload. Ultrastructurally, the atrial muscle cells in these patients appeared normal and measured 6 to 12 mu in diameter. The six patients with an endocardial cushion defect had elevated right atrial mean pressure and evidence of right atrial volume overload. Ultrastructurally, the atrial muscle cells in these patients were generally larger than 12 mu in diameter. The cells were irregular and had multiple and occasionally widened intercalated discs. In addition, there were degenerative changes in two patients with markedly increased atrial pressure. These changes included extensive loss of contractile elements, aggregation of small irregular mitochondria and proliferation of tubules of the sarcoplasmic reticulum. The structural changes suggest that hypertrophy of the right atrium may be secondary to volume overload of the atrium, whereas degenerative changes may be secondary to increased right atrial pressure.
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Abstract
Human metaphase chromosomes, fixed in methanol-acetic acid, were ultraviolet irradiated to produce single-stranded regions of chromosomal DNA and treated with anti-5-methylcytidine. Using an immunoperoxidase procedure, regions of antibody binding were readily visualized by light microscopy in the centromeric heterochromatin regions of chromosomes 1, 9, 16, the short arm of chromosome 15, and in the distal portion of the Y. Electron microscopic visualization of the same whole mount chromosome preparations transferred to formvarcoated grids revealed additional details of the distribution and arrangement of 5-methylcytosine. A helical arrangement of 5-methylcytosine residues was seen below the centromere of chromosome 1. The Y chromosome showed a concentration of 5-methylcytosine residues on the distal long arm, and in areas just below and slightly above the centromere. In all the above chromosomes, especially chromosome 15, additional 5-methylcytosine residues were detected as isolated foci along the arms. Our findings support the concept that clusters of similar purine or pyrimidine residues exist along the arms of condensed metaphase chromosomes, with the possibility that concentrations of 5-methylcytosine residues might have been enhanced at the surface of the chromosomes during the condensation process.
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Azar HA, Zaino EC, Pham TD, Yannopoulos K. "Nonsecretory" plasma cell myeloma: observations on seven cases with electron microscopic studies. Am J Clin Pathol 1972; 58:618-29. [PMID: 4629768 DOI: 10.1093/ajcp/58.6.618] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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