201
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Hietavala EM, Ihalainen JK, Frassetto LA, Schumann M, Eklund D, Pitkänen H, Häkkinen K, Mero AA. Effects of 12-Week Low or Moderate Dietary Acid Intake on Acid-Base Status and Kidney Function at Rest and during Submaximal Cycling. Nutrients 2018. [PMID: 29517990 PMCID: PMC5872741 DOI: 10.3390/nu10030323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Prolonged effects of dietary acid intake on acid–base status and kidney function have not yet been studied in an intervention study in healthy subjects. Dietary acid load can be estimated by calculating the potential renal acid load (PRAL) of foods. Effects of low-PRAL and moderate-PRAL diets on acid–base status and kidney function were investigated during a 12-week exercise training period. Healthy, 20–50-year-old men (n = 21) and women (n = 25) participated in the study and were randomly divided into low-PRAL and moderate-PRAL groups. Before (PRE), mid-phase (MID) and after the intervention (POST), the subjects participated in measurement sessions, where a 12-h urine sample and fasting blood samples were collected, and a submaximal cycle ergometer test was performed. Net acid excretion was significantly lower after 12 weeks of the low-PRAL diet as compared to the moderate-PRAL diet, both in men and women. In low-PRAL females, capillary pH and bicarbonate were significantly higher at 75% of VO2max at POST as compared to PRE. Glomerular filtration rate decreased over the study period in moderate-PRAL men and women. The results of the present study suggest that an acidogenic diet and regularly training together may increase the acidic load of the body and start to impair the kidney function in recreationally active subjects.
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Affiliation(s)
- Enni-Maria Hietavala
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35 (VIV), 40014 Jyväskylä, Finland.
| | - Johanna K Ihalainen
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35 (VIV), 40014 Jyväskylä, Finland.
| | - Lynda A Frassetto
- General Clinical Research Center, University of California San Francisco, 505 Parnassus Avenue, San Francisco, CA 94117, USA.
| | - Moritz Schumann
- Department of Molecular and Cellular Sports Medicine, German Sport University, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
| | - Daniela Eklund
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35 (VIV), 40014 Jyväskylä, Finland.
| | - Hannu Pitkänen
- Honka Holding, c/o Honkatarhat Oy, Kirkkokallio 20, 38950 Honkajoki, Finland.
| | - Keijo Häkkinen
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35 (VIV), 40014 Jyväskylä, Finland.
| | - Antti A Mero
- Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35 (VIV), 40014 Jyväskylä, Finland.
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202
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Lee HW, Osis G, Harris AN, Fang L, Romero MF, Handlogten ME, Verlander JW, Weiner ID. NBCe1-A Regulates Proximal Tubule Ammonia Metabolism under Basal Conditions and in Response to Metabolic Acidosis. J Am Soc Nephrol 2018; 29:1182-1197. [PMID: 29483156 DOI: 10.1681/asn.2017080935] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 01/10/2018] [Indexed: 12/16/2022] Open
Abstract
Renal ammonia metabolism is the primary mechanism through which the kidneys maintain acid-base homeostasis, but the molecular mechanisms regulating renal ammonia generation are unclear. In these studies, we evaluated the role of the proximal tubule basolateral plasma membrane electrogenic sodium bicarbonate cotransporter 1 variant A (NBCe1-A) in this process. Deletion of the NBCe1-A gene caused severe spontaneous metabolic acidosis in mice. Despite this metabolic acidosis, which normally causes a dramatic increase in ammonia excretion, absolute urinary ammonia concentration was unaltered. Additionally, NBCe1-A deletion almost completely blocked the ability to increase ammonia excretion after exogenous acid loading. Under basal conditions and during acid loading, urine pH was more acidic in mice with NBCe1-A deletion than in wild-type controls, indicating that the abnormal ammonia excretion was not caused by a primary failure of urine acidification. Instead, NBCe1-A deletion altered the expression levels of multiple enzymes involved in proximal tubule ammonia generation, including phosphate-dependent glutaminase, phosphoenolpyruvate carboxykinase, and glutamine synthetase, under basal conditions and after exogenous acid loading. Deletion of NBCe1-A did not impair expression of key proteins involved in collecting duct ammonia secretion. These studies demonstrate that the integral membrane protein NBCe1-A has a critical role in basal and acidosis-stimulated ammonia metabolism through the regulation of proximal tubule ammonia-metabolizing enzymes.
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Affiliation(s)
- Hyun-Wook Lee
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Gunars Osis
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Autumn N Harris
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Lijuan Fang
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota; and
| | - Mary E Handlogten
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Transplantation, University of Florida College of Medicine, Gainesville, Florida; .,Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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203
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Harris AN, Grimm PR, Lee HW, Delpire E, Fang L, Verlander JW, Welling PA, Weiner ID. Mechanism of Hyperkalemia-Induced Metabolic Acidosis. J Am Soc Nephrol 2018; 29:1411-1425. [PMID: 29483157 DOI: 10.1681/asn.2017111163] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/03/2018] [Indexed: 12/22/2022] Open
Abstract
Background Hyperkalemia in association with metabolic acidosis that are out of proportion to changes in glomerular filtration rate defines type 4 renal tubular acidosis (RTA), the most common RTA observed, but the molecular mechanisms underlying the associated metabolic acidosis are incompletely understood. We sought to determine whether hyperkalemia directly causes metabolic acidosis and, if so, the mechanisms through which this occurs.Methods We studied a genetic model of hyperkalemia that results from early distal convoluted tubule (DCT)-specific overexpression of constitutively active Ste20/SPS1-related proline-alanine-rich kinase (DCT-CA-SPAK).Results DCT-CA-SPAK mice developed hyperkalemia in association with metabolic acidosis and suppressed ammonia excretion; however, titratable acid excretion and urine pH were unchanged compared with those in wild-type mice. Abnormal ammonia excretion in DCT-CA-SPAK mice associated with decreased proximal tubule expression of the ammonia-generating enzymes phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase and overexpression of the ammonia-recycling enzyme glutamine synthetase. These mice also had decreased expression of the ammonia transporter family member Rhcg and decreased apical polarization of H+-ATPase in the inner stripe of the outer medullary collecting duct. Correcting the hyperkalemia by treatment with hydrochlorothiazide corrected the metabolic acidosis, increased ammonia excretion, and normalized ammoniagenic enzyme and Rhcg expression in DCT-CA-SPAK mice. In wild-type mice, induction of hyperkalemia by administration of the epithelial sodium channel blocker benzamil caused hyperkalemia and suppressed ammonia excretion.Conclusions Hyperkalemia decreases proximal tubule ammonia generation and collecting duct ammonia transport, leading to impaired ammonia excretion that causes metabolic acidosis.
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Affiliation(s)
- Autumn N Harris
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - P Richard Grimm
- Department of Physiology and Maryland Center for Kidney Discovery, University of Maryland School of Medicine, Baltimore, Maryland
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Lijuan Fang
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Paul A Welling
- Department of Physiology and Maryland Center for Kidney Discovery, University of Maryland School of Medicine, Baltimore, Maryland
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; .,Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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204
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Worcester EM, Bergsland KJ, Gillen DL, Coe FL. Mechanism for higher urine pH in normal women compared with men. Am J Physiol Renal Physiol 2017; 314:F623-F629. [PMID: 29357436 DOI: 10.1152/ajprenal.00494.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Regulation of acid-base metabolism maintains the pH of body fluids within a tight range. Urine pH (UpH) is also regulated under normal conditions. Median pH of 24-h urines is ~6, but others have noted that UpH in women is higher than men, which has been attributed to differences in diet. If true, it would help to explain the fact that calcium phosphate stones, which form at higher urine pH, are much more common in women than in men. We studied 14 normal subjects (7 men and 7 women) fed identical meals in a Clinical Research Center. Urine and blood samples were collected during fasting and after meals. UpH of women (6.74 ± 0.11) exceeded that of men (6.07 ± 0.17) fed, but not fasting, and UpH rose significantly with meals in women but not men. Serum and urine total CO2 rose with meals in women but not men, and in women net acid excretion fell to zero during the fed period. In a general linear model adjusted for age, sex, and weight, net gastrointestinal anion uptake was the main predictor of UpH and was significantly higher in women (3.9 ± 0.6) than men (1.8 ± 0.7) in the fed period. Urine citrate, an anion absorbed by the gastrointestinal tract, was higher in women than men in the fed state, and fractional excretion of citrate was higher in women than men. The higher fed UpH in women is related to a greater absorption of food anions and raises 24-h UpH.
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Affiliation(s)
- Elaine M Worcester
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | | | - Daniel L Gillen
- Department of Statistics, University of California , Irvine, California
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
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205
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Pourafshar N, Pourafshar S, Soleimani M. Urine Ammonium, Metabolic Acidosis and Progression of Chronic Kidney Disease. Nephron Clin Pract 2017; 138:222-228. [PMID: 29050011 DOI: 10.1159/000481892] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/28/2017] [Indexed: 11/19/2022] Open
Abstract
The metabolism of a typical Western diet generates 50-100 mEq of acid (H+) per day, which must be excreted in the urine for the systemic acid-base to remain in balance. The 2 major mechanisms that are responsible for the renal elimination of daily acid under normal conditions are ammonium (NH4+) excretion and titratable acidity. In the presence of systemic acidosis, ammonium excretion is intensified and becomes the crucial mechanism for the elimination of acid. The impairment in NH4+ excretion is therefore associated with reduced acid excretion, which causes excess accumulation of acid in the body and consequently results in metabolic acidosis. Chronic kidney disease (CKD) is associated with the impairment in acid excretion and precipitation of metabolic acidosis, which has an adverse effect on the progression of CKD. Recent studies suggest that the progressive decline in renal ammonium excretion in CKD is an important determinant of the ensuing systemic metabolic acidosis and is an independent factor for predicting the worsening of kidney function. While these studies have been primarily performed in hypertensive individuals with CKD, a closer look at renal NH4+ excretion in non-hypertensive individuals with CKD is warranted to ascertain its role in the progression of kidney disease.
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Affiliation(s)
- Negiin Pourafshar
- Department of Medicine at University of Virginia, Charlottesville, Virginia, USA
| | - Shirin Pourafshar
- Department of Medicine at University of Virginia, Charlottesville, Virginia, USA
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA.,Department of Medicine Services, Veterans Medical Center, Cincinnati, Ohio, USA
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206
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Nagami GT, Hamm LL. Regulation of Acid-Base Balance in Chronic Kidney Disease. Adv Chronic Kidney Dis 2017; 24:274-279. [PMID: 29031353 DOI: 10.1053/j.ackd.2017.07.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/28/2017] [Indexed: 11/11/2022]
Abstract
The kidneys play a major role in the regulation of acid-base balance by reabsorbing bicarbonate filtered by the glomeruli and excreting titratable acids and ammonia into the urine. In CKD, with declining kidney function, acid retention and metabolic acidosis occur, but the extent of acid retention depends not only on the degree of kidney impairment but also on the dietary acid load. Acid retention can occur even when the serum bicarbonate level is apparently normal. With reduced kidney function, acid transport processes in the surviving nephrons are augmented but as disease progresses ammonia excretion and, in some individuals, the ability to reabsorb bicarbonate falls, whereas titratable acid excretion is preserved until kidney function is severely impaired. Urinary ammonia levels are used to gauge the renal response to acid loads and are best assessed by direct measurement of urinary ammonia levels rather than by indirect assessments. In individuals with acidosis from CKD, an inappropriately low degree of ammonia excretion points to the pathogenic role of impaired urinary acid excretion. The presence of a normal bicarbonate level in CKD complicates the interpretation of the urinary ammonia excretion as such individuals could be in acid-base balance or could be retaining acid without manifesting a low bicarbonate level. At this time, the decision to give bicarbonate supplementation in CKD is reserved for those with a bicarbonate level of 22 mEq/L, but because of potential harm of overtreatment, supplementation should be adjusted to maintain a bicarbonate level of <26 mEq/L.
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207
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Hamilton PK, Morgan NA, Connolly GM, Maxwell AP. Understanding Acid-Base Disorders. THE ULSTER MEDICAL JOURNAL 2017; 86:161-166. [PMID: 29581626 PMCID: PMC5849971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 01/08/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Paul K. Hamilton
- Specialty Registrar in Chemical Pathology (Metabolic Medicine), Belfast Health and Social Care Trust; Honorary Lecturer, Queen’s University Belfast
| | - Neal A. Morgan
- Consultant Nephrologist, Southern Health and Social Care Trust
| | | | - Alexander P. Maxwell
- Consultant Nephrologist, Belfast Health and Social Care Trust,Correspondence to Prof AP Maxwell. Address: Regional Nephrology Unit, Belfast City Hospital, Belfast, BT9 7AB, United Kingdom.
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208
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Lee S, Park J, Li JM, Li K, Choi I. Evidence for ammonium conductance in a mouse thick ascending limb cell line. Physiol Rep 2017; 5:5/16/e13379. [PMID: 28830978 PMCID: PMC5582264 DOI: 10.14814/phy2.13379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/23/2017] [Accepted: 07/14/2017] [Indexed: 12/21/2022] Open
Abstract
In this study, we examined an ammonium conductance in the mouse thick ascending limb cell line ST-1. Whole cell patch clamp was performed to measure currents evoked by NH4Cl in the presence of BaCl2, tetraethylammonium, and BAPTA Application of 20 mmol/L NH4Cl induced an inward current (-272 ± 79 pA, n = 9). In current-voltage (I-V) relationships, NH4Cl application caused the I-V curve to shift down in an inward direction. The difference in current before and after NH4Cl application, which corresponds to the current evoked by NH4Cl, was progressively larger at more negative potentials. The reversal potential for NH4Cl was +15 mV, higher than the equilibrium potential for chloride, indicating that the current should be due to NH4+ We then injected ST-1 poly(A) RNA into Xenopus oocytes and performed two-electrode voltage clamp. NH4Cl application in the presence of BaCl2 caused the I-V curve to be steeper. The NH4+ current was retained at pH 6.4, where endogenous oocyte current was abolished. The NH4+ current was unaffected by 10 μmol/L amiloride but abolished after incubation in Na+-free media. These results demonstrate that the renal cell line ST-1 produces an NH4+ conductance.
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Affiliation(s)
- Soojung Lee
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Jonathan Park
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Jun Ming Li
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Kathy Li
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Inyeong Choi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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209
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Affiliation(s)
- KowsalyaDevi Pavuluri
- Russell H. Morgan Department of Radiology and Radiological Science; Johns Hopkins University School of Medicine; Baltimore, Maryland 21205 United States
| | - Michael T. McMahon
- Russell H. Morgan Department of Radiology and Radiological Science; Johns Hopkins University School of Medicine; Baltimore, Maryland 21205 United States
- F. M. Kirby Research Center for Functional Brain Imaging; Kennedy Krieger Research Institute; Baltimore, Maryland 21205 United States
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210
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Longo DL, Cutrin JC, Michelotti F, Irrera P, Aime S. Noninvasive evaluation of renal pH homeostasis after ischemia reperfusion injury by CEST-MRI. NMR IN BIOMEDICINE 2017; 30:e3720. [PMID: 28370530 DOI: 10.1002/nbm.3720] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 02/06/2017] [Accepted: 02/06/2017] [Indexed: 06/07/2023]
Abstract
Acute kidney injury (AKI) in mice caused by sustained ischemia followed by reperfusion is associated with acute tubular necrosis and renal dysfunctional blood flow. Although the principal role of the kidney is the maintenance of acid-base balance, current imaging approaches are unable to assess this important parameter, and clinical biomarkers are not robust enough in evaluating the severity of kidney damage. Therefore, novel noninvasive imaging approaches are needed to assess the acid-base homeostasis in vivo. This study investigates the usefulness of MRI-chemical exchange saturation transfer (CEST) pH imaging (through iopamidol injection) in characterizing moderate and severe AKI in mice following unilateral ischemia reperfusion injury. Moderate (20 min) and severe (40 min) ischemia were induced in Balb/C mice, which were imaged at several time points thereafter (Days 0, 1, 2, 7). A significant increase of renal pH values was observed as early as one day after the ischemia reperfusion damage for both moderate and severe ischemia. MRI-CEST pH imaging distinguished the evolution of moderate from severe AKI. A recovery of normal renal pH values was observed for moderate AKI, whereas a persisting renal pH increase was observed for severe AKI on Day 7. Renal filtration fraction was significantly lower for clamped kidneys (0.54-0.57) in comparison to contralateral kidneys (0.84-0.86) following impairment of glomerular filtration. The severe AKI group showed a reduced filtration fraction even after 7 days (0.38 for the clamped kidneys). Notably, renal pH values were significantly correlated with the histopathological score. In conclusion, MRI-CEST pH mapping is a valid tool for the noninvasive evaluation of both acid-base balance and renal filtration in patients with ischemia reperfusion injury.
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Affiliation(s)
- Dario Livio Longo
- Istituto di Biostrutture e Bioimmagini (CNR), c/o Centro di Biotecnologie Molecolari, Torino, Italy
- Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Università degli Studi di Torino, Torino, Italy
| | - Juan Carlos Cutrin
- Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Università degli Studi di Torino, Torino, Italy
| | - Filippo Michelotti
- Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Università degli Studi di Torino, Torino, Italy
| | - Pietro Irrera
- Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Università degli Studi di Torino, Torino, Italy
| | - Silvio Aime
- Dipartimento di Biotecnologie Molecolari e Scienze per la Salute, Università degli Studi di Torino, Torino, Italy
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211
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Weiner ID. Roles of renal ammonia metabolism other than in acid-base homeostasis. Pediatr Nephrol 2017; 32:933-942. [PMID: 27169421 PMCID: PMC5107182 DOI: 10.1007/s00467-016-3401-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 02/06/2023]
Abstract
The importance of renal ammonia metabolism in acid-base homeostasis is well known. However, the effects of renal ammonia metabolism other than in acid-base homeostasis are not as widely recognized. First, ammonia differs from almost all other solutes in the urine in that it does not result from arterial delivery. Instead, ammonia is produced by the kidney, and only a portion of the ammonia produced is excreted in the urine, with the remainder returned to the systemic circulation through the renal veins. In normal individuals, systemic ammonia addition is metabolized efficiently by the liver, but in patients with either acute or chronic liver disease, conditions that increase the addition of ammonia of renal origin to the systemic circulation can result in precipitation and/or worsening of hyperammonemia. Second, ammonia appears to serve as an intrarenal paracrine signaling molecule. Hypokalemia increases proximal tubule ammonia production and secretion as well as reabsorption in the thick ascending limb of the loop of Henle, thereby increasing delivery to the renal interstitium and the collecting duct. In the collecting duct, ammonia decreases potassium secretion and stimulates potassium reabsorption, thereby decreasing urinary potassium excretion and enabling feedback correction of the initiating hypokalemia. Finally, the stimulation of renal ammonia metabolism by hypokalemia may contribute to the development of metabolic alkalosis, which in turn can stimulate NaCl reabsorption and contribute to the intravascular volume expansion, increased blood pressure and diuretic resistance that can develop with hypokalemia. The evidence supporting these novel non-acid-base roles of renal ammonia metabolism is discussed in this review.
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Affiliation(s)
- I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, PO Box 100224, Gainesville, FL, 32610-0224, USA.
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, FL, USA.
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212
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Peng L, Liu S, Feng A, Yuan J. Polymeric Nanocarriers Based on Cyclodextrins for Drug Delivery: Host–Guest Interaction as Stimuli Responsive Linker. Mol Pharm 2017; 14:2475-2486. [DOI: 10.1021/acs.molpharmaceut.7b00160] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Liao Peng
- Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Senyang Liu
- Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Anchao Feng
- College
of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China
| | - Jinying Yuan
- Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
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213
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Szermer-Olearnik B, Drab M, Mąkosa M, Zembala M, Barbasz J, Dąbrowska K, Boratyński J. Aggregation/dispersion transitions of T4 phage triggered by environmental ion availability. J Nanobiotechnology 2017; 15:32. [PMID: 28438164 PMCID: PMC5404661 DOI: 10.1186/s12951-017-0266-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 04/10/2017] [Indexed: 11/24/2022] Open
Abstract
Background Bacteriophage survives in at least two extremes of ionic environments: bacterial host (high ionic-cytosol) and that of soil (low ionic-environmental water). The impact of ionic composition in the micro- and macro-environments has not so far been addressed in phage biology. Results Here, we discovered a novel mechanism of aggregation/disaggregation transitions by phage virions. When normal sodium levels in phage media (150 mM) were lowered to 10 mM, advanced imaging by scanning electron microscopy, atomic force microscopy and dynamic light scattering all revealed formation of viral packages, each containing 20–100 virions. When ionic strength was returned from low to high, the aggregated state of phage reversed to a dispersed state, and the change in ionic strength did not substantially affect infectivity of the phage. By providing the direct evidence, that lowering of the sodium ion below the threshold of 20 mM causes rapid aggregation of phage while returning Na+ concentration to the values above this threshold causes dispersion of phage, we identified a biophysical mechanism of phage aggregation. Conclusions Our results implicate operation of group behavior in phage and suggest a new kind of quorum sensing among its virions that is mediated by ions. Loss of ionic strength may act as a trigger in an evolutionary mechanism to improve the survival of bacteriophage by stimulating aggregation of phage when outside a bacterial host. Reversal of phage aggregation is also a promising breakthrough in biotechnological applications, since we demonstrated here the ability to retain viable virion aggregates on standard micro-filters.
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Affiliation(s)
- Bożena Szermer-Olearnik
- Laboratory of Biomedical Chemistry-"Neolek". Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wroclaw, Poland
| | - Marek Drab
- USI, Unit of Nanostructural Bio-Interactions, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wrocław, Poland
| | - Mateusz Mąkosa
- Laboratory of Biomedical Chemistry-"Neolek". Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wroclaw, Poland
| | - Maria Zembala
- Institute of Biology, Pedagogical University of Cracow, Podchorążych 2, 30-084, Cracow, Poland
| | - Jakub Barbasz
- Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Cracow, Poland
| | - Krystyna Dąbrowska
- Bacteriophage Laboratory, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wrocław, Poland
| | - Janusz Boratyński
- Laboratory of Biomedical Chemistry-"Neolek". Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wroclaw, Poland. .,Institute of Chemistry, Environmental Protection and Biotechnology, Jan Długosz University, 42-200, Częstochowa, Poland.
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214
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Darriet C, Axe DE, Crenshaw TD. Acidogenic mineral additions increased Ca mobilization in prepartum sows. J Anim Sci 2017; 95:212-225. [PMID: 28177393 DOI: 10.2527/jas.2016.0859] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Increased sow milk production is associated with an increase in unexplained sow mortality during prepartum and early postpartum periods. This association has led to purported claims of hypocalcemic disorders. Assuming similar responses as dairy cows, feeding anionic mineral salts in late gestation and early lactation may reduce potential hypocalcemia related disorders in sows. Two experiments using CAD-MATE (Granco Minerals, Petersburg, VA), an acidogenic mineral supplement (AMS), were designed to determine the amount required to increase urinary Ca excretion and to identify renal compensatory responses to acid loads in sows. In Exp. 1, 30 multiparous gestating sows (Landrace × Large White) were fed 1 of 6 diets with either 0, 0.5, 1.0, 1.5, 2.0, or 2.5% AMS additions for 14 d. Diets provided a range (33 to -216 mEq/kg) of cation-anion balance, calculated as Na + K - Cl - S. Two 24-h urine samples were collected via bladder catheters for mineral analysis. One venous blood sample was drawn from 2 sows per diet on d 14. In Exp. 2, twelve sows were fed 1 of 3 diets to provide either 0, 1.5, or 2.5% AMS. Three 24-h composites of urine and fecal excreta were collected and analyses were used to calculate apparent mineral retention. Venous blood pH (range 7.41 to 7.33) and base excess (range 5.4 to 0.5 mmol/L) decreased (linear, < 0.10), but blood ionized Ca (range 1.28 to 1.37 mmol/L) increased (linear, < 0.05) proportionally to dietary AMS additions. Blood anion gap was not affected by diet. Urine pH decreased (linear, < 0.10) with additions of AMS (range 7.47 to 5.52). In Exp. 2, urinary SO (range 134 to 396 mEq/d) and NH (range 84 to 323 mEq/d) excretion increased ( < 0.05) with AMS additions. Urinary Mg, Na, and K excretion did not differ among treatments. Fecal excretion of Ca, Mg, and P increased ( < 0.05) in sows fed diets with 2.5% AMS. Fecal K, Na, and Cl excretion did not differ among treatments. Apparent Ca retention decreased ( < 0.05) with AMS additions, but apparent Mg and Cl retention increased ( < 0.05). In conclusion, AMS induced a renal compensated acid load as exhibited by urinary ion excretion patterns and maintenance of blood gas values within physiological ranges. Feeding diets with 1.5 or 2.5% AMS increased urinary and fecal Ca excretion and decreased apparent Ca retention implying an increase in mobilization of body Ca pools in prepartum sows.
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215
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Guo YM, Liu Y, Liu M, Wang JL, Xie ZD, Chen KJ, Wang DK, Occhipinti R, Boron WF, Chen LM. Na +/HCO 3- Cotransporter NBCn2 Mediates HCO 3- Reclamation in the Apical Membrane of Renal Proximal Tubules. J Am Soc Nephrol 2017; 28:2409-2419. [PMID: 28280139 DOI: 10.1681/asn.2016080930] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/23/2017] [Indexed: 12/31/2022] Open
Abstract
The kidney maintains systemic acid-base balance by reclaiming from the renal tubule lumen virtually all HCO3- filtered in glomeruli and by secreting additional H+ to titrate luminal buffers. For proximal tubules, which are responsible for about 80% of this activity, it is believed that HCO3- reclamation depends solely on H+ secretion, mediated by the apical Na+/H+ exchanger NHE3 and the vacuolar proton pump. However, NHE3 and the proton pump cannot account for all HCO3- reclamation. Here, we investigated the potential contribution of two variants of the electroneutral Na+/HCO3- cotransporter NBCn2, the amino termini of which start with the amino acids MCDL (MCDL-NBCn2) and MEIK (MEIK-NBCn2). Western blot analysis and immunocytochemistry revealed that MEIK-NBCn2 predominantly localizes at the basolateral membrane of medullary thick ascending limbs in the rat kidney, whereas MCDL-NBCn2 localizes at the apical membrane of proximal tubules. Notably, NH4Cl-induced systemic metabolic acidosis or hypokalemic alkalosis downregulated the abundance of MCDL-NBCn2 and reciprocally upregulated NHE3 Conversely, NaHCO3-induced metabolic alkalosis upregulated MCDL-NBCn2 and reciprocally downregulated NHE3 We propose that the apical membrane of the proximal tubules has two distinct strategies for HCO3- reclamation: the conventional indirect pathway, in which NHE3 and the proton pump secrete H+ to titrate luminal HCO3-, and the novel direct pathway, in which NBCn2 removes HCO3- from the lumen. The reciprocal regulation of NBCn2 and NHE3 under different physiologic conditions is consistent with our mathematical simulations, which suggest that HCO3- uptake and H+ secretion have reciprocal efficiencies for HCO3- reclamation versus titration of luminal buffers.
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Affiliation(s)
- Yi-Min Guo
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Ying Liu
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Mei Liu
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Jin-Lin Wang
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Zhang-Dong Xie
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Kang-Jing Chen
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
| | - Deng-Ke Wang
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Rossana Occhipinti
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Walter F Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Li-Ming Chen
- Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei, China; and
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216
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Ivashchenko O, Woźniak A, Coy E, Peplinska B, Gapinski J, Jurga S. Release and cytotoxicity studies of magnetite/Ag/antibiotic nanoparticles: An interdependent relationship. Colloids Surf B Biointerfaces 2017; 152:85-94. [PMID: 28088016 DOI: 10.1016/j.colsurfb.2017.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 01/20/2023]
Abstract
Though the cytotoxic properties of magnetite nanoparticles (NPs) are rather well investigated and known to be dose dependent and rather low, surface functionalization can drastically change their properties. To determine whether the cytotoxicity of magnetite/Ag/antibiotic NPs may be associated, among other things, with iron, silver and antibiotic release, this study investigates the release profiles and cytotoxicity of magnetite/Ag/rifampicin and magnetite/Ag/doxycycline NPs compares it similar profiles from magnetite, magnetite/Ag NPs and antibiotics. It was established that the studied NPs released not only water-soluble substances, such as antibiotics, but also poorly-soluble ones, such as iron and silver. The deposition of silver on the magnetite surface promotes the release of iron by the formation of a galvanic couple. Antibiotic adsorbed on the magnetite/Ag surface plays a dual role in the galvanic corrosion processes: as a corrosion inhibitor for iron oxides and as a corrosion promoter for silver. Magnetite/Ag/rifampicin and magnetite/Ag/doxycycline. NPs were found to have greater cytotoxicity towards the HEK293T cell line than magnetite NPs. These results were attributed to the combined toxic action of the released iron, silver ions and antibiotics. Intensive and simultaneous release of the NP components caused cell stress and suppressed their growth.
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Affiliation(s)
- Olena Ivashchenko
- NanoBioMedical Centre, Adam Mickiewicz University, 61614 Poznan, Poland.
| | - Anna Woźniak
- NanoBioMedical Centre, Adam Mickiewicz University, 61614 Poznan, Poland
| | - Emerson Coy
- NanoBioMedical Centre, Adam Mickiewicz University, 61614 Poznan, Poland
| | - Barbara Peplinska
- NanoBioMedical Centre, Adam Mickiewicz University, 61614 Poznan, Poland
| | - Jacek Gapinski
- Department of Molecular Biophysics, Faculty of Physics, A. Mickiewicz University, Poznań, Poland
| | - Stefan Jurga
- NanoBioMedical Centre, Adam Mickiewicz University, 61614 Poznan, Poland; Department of Macromolecular Physics, Adam Mickiewicz University, 61614 Poznan, Poland
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217
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Ring T, Kellum JA. Strong Relationships in Acid-Base Chemistry - Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2. PLoS One 2016; 11:e0162872. [PMID: 27631369 PMCID: PMC5025046 DOI: 10.1371/journal.pone.0162872] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/31/2016] [Indexed: 11/18/2022] Open
Abstract
Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice. Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and pH based on all other charged moieties. Therefore, to validate this construct we investigated a large number of blood samples from intensive care patients, where both data and pathology is plentiful, by comparing the measured pH to the modeled pH. We were able to predict both the mean pattern and the individual fluctuation in pH based on all other measured charges with a correlation of approximately 90% in individual patient series. However, there was a shift in pH so that fitted pH in general is overestimated (95% confidence interval -0.072-0.210) and we examine some explanations for this shift. Having confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights with important implications for medicine and physiology. Importantly this construct should pave the way for quantitative acid-base models looking into the underlying mechanisms of disorders rather than just classifying them.
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Affiliation(s)
- Troels Ring
- Department of Nephrology. Aalborg University Hospital. Aalborg 9000, Denmark
| | - John A. Kellum
- The Center for Critical Care Nephrology. Department of Critical Care Medicine, University of Pittsburgh School of Medicine, and University of Pittsburgh Medical Center, Pittsburgh, PA, United States of America
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218
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Vandendriessche VL, Dufourni A, Loon G, Hesta M. Successful nutritional management of a 21‐year‐old Quarter Horse gelding with acute renal failure. VETERINARY RECORD CASE REPORTS 2016. [DOI: 10.1136/vetreccr-2016-000309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Alexander Dufourni
- Department of Large Animal Internal MedicineFaculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | - Gunther Loon
- Department of Large Animal Internal MedicineFaculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
| | - Myriam Hesta
- Laboratory of Animal NutritionFaculty of Veterinary MedicineGhent UniversityMerelbekeBelgium
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219
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Atkinson KF, Nauli SM. pH sensors and ion Transporters: Potential therapeutic targets for acid-base disorders. INTERNATIONAL JOURNAL OF PHARMA RESEARCH & REVIEW 2016; 5:51-58. [PMID: 29796385 PMCID: PMC5963282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Regulation of pH is critical for physiological processes. Maintenance of acid-base homeostasis is tightly regulated by the renal and respiratory systems. However, fluctuations in extracellular pH are also sensed by other organ systems. Ion transporter activity to modify the amount of acid (H+ and CO2) and bicarbonate (HCO3-) is therefore actively maintained within the kidney and lung. This review describes acid-base disorders (acidosis and alkalosis) and highlights the importance of pH sensors and ion transporters that may be potential therapeutic targets for treatment of acid-base disorders. Specifically, the renal pH sensors proline-rich tyrosine kinase-2 (Pyk2) and G-protein coupled receptor-4 (GPR4) are discussed here.
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Affiliation(s)
- Kimberly F Atkinson
- Department of Biomedical & Pharmaceutical Sciences, Chapman University, Irvine, CA, USA
| | - Surya M Nauli
- Department of Biomedical & Pharmaceutical Sciences, Chapman University, Irvine, CA, USA
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