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Liu B, Liang T, Qi W, Zhong A, Chen M, Lu Y, Chen J, Chen D, Wang J. A new electrochemical angular microaccelerometer with integrated sensitive electrodes perpendicular to flow channels. Microsyst Nanoeng 2022; 8:80. [PMID: 35846174 PMCID: PMC9276652 DOI: 10.1038/s41378-022-00411-0] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/02/2022] [Accepted: 04/05/2022] [Indexed: 06/15/2023]
Abstract
A new electrochemical angular microaccelerometer with integrated sensitive electrodes perpendicular to flow channels was developed in this paper. Based on a liquid inertial mass, an incoming angular acceleration was translated into varied concentrations of reactive ions around sensitive microelectrodes, generating a detection current. Key structural parameters of the sensitive microelectrodes were designed and compared based on theoretical analysis and numerical simulations. An angular microaccelerometer incorporating sensitive microelectrodes was then fabricated, assembled and characterized, producing a sensitivity of 338 V/(rad/s2), a -3 dB bandwidth of 0.01-10 Hz and a noise level of 4.67 × 10-8 (rad/s2)/Hz1/2 @ 1 Hz. These performances were better than their commercial counterparts based on traditional electrodes and previously reported microaccelerometers based on microsensitive electrodes in parallel with flow channels, which can be applied to measure rotational accelerations in earthquakes and buildings.
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Affiliation(s)
- Bowen Liu
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Tian Liang
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Wenjie Qi
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Anxiang Zhong
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Mingwei Chen
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yulan Lu
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Jian Chen
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Deyong Chen
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Junbo Wang
- The State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, 100190 Beijing, China
- The School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, 100049 Beijing, China
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Zhong A, Trerotola S, Stavropoulos S. Abstract No. 149 Endobronchial forceps retrieval of embedded inferior vena cava filters: retrieval of 545 filters at a single center. J Vasc Interv Radiol 2022. [DOI: 10.1016/j.jvir.2022.03.230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Chen M, Zhong A, Lu Y, Chen J, Chen D, Wang J. A MEMS Electrochemical Angular Accelerometer Leveraging Silicon-Based Three-Electrode Structure. Micromachines (Basel) 2022; 13:mi13020186. [PMID: 35208310 PMCID: PMC8875607 DOI: 10.3390/mi13020186] [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] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/24/2022]
Abstract
This paper developed an electrochemical angular micro-accelerometer using a silicon-based three-electrode structure as a sensitive unit. Angular acceleration was translated to ion changes around sensitive microelectrodes, and the adoption of the silicon-based three-electrode structure increased the electrode area and the sensitivity of the device. Finite element simulation was conducted for geometry optimization where the anode length, the orifice diameter, and the orifice spacing of the sensitive unit were determined as 200 μm, 80 μm, and 500 μm, respectively. Microfabrication was conducted to manufacture the silicon-based three-electrode structure, which then was assembled to form the electrochemical angular micro-accelerometer, leveraging mechanical compression. Device characterization was conducted, where the sensitivity, bandwidth, and noise level were quantified as 290.193 V/(rad/s2) at 1 Hz, 0.01–2 Hz, and 1.78 × 10−8 (rad/s2)/Hz1/2 at 1 Hz, respectively. Due to the inclusion of the silicon-based three-electrode structure, compared with previously reported electrochemical angular accelerometers, the angular accelerometer developed in this article was featured with a higher sensitivity and a lower self-noise level. Therefore, it could be used for the measurement of low-frequency seismic rotation signals and played a role in the seismic design of building structures.
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Affiliation(s)
- Mingwei Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Anxiang Zhong
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yulan Lu
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deyong Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (D.C.); (J.W.); Tel.: +86-010-588-87182 (D.C.); +86-010-588-87191 (J.W.)
| | - Junbo Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (M.C.); (A.Z.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (D.C.); (J.W.); Tel.: +86-010-588-87182 (D.C.); +86-010-588-87191 (J.W.)
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Zhong A, Chen M, Lu Y, Chen J, Chen D, Wang J. A MEMS-Based Co-Oscillating Electrochemical Vector Hydrophone. Micromachines 2022; 13:mi13010143. [PMID: 35056308 PMCID: PMC8778131 DOI: 10.3390/mi13010143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 02/04/2023]
Abstract
Aiming at the development needs of low-frequency and high-sensitivity vector hydrophones, this paper has developed a micro-electro-mechanical system (MEMS) based co-oscillating electrochemical vector hydrophone. We obtained the optimized geometric parameters through simulation analysis of the diameter of the rubber membrane, the length of the flow channel and the diameter of the flow holes. Based on the simulation results, electrodes were fabricated using MEMS technology, and were then assembled and tested. Device characterization was conducted, where the sensitivity and bandwidth were quantified as 0.5–150 Hz, −187 dB ref. 1 V/μPa, respectively. Compared with a previously reported co-oscillating vector hydrophone, the co-oscillating vector hydrophone developed in this article featured a lower working frequency band.
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Affiliation(s)
- Anxiang Zhong
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingwei Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yulan Lu
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deyong Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (D.C.); (J.W.); Tel.: +86-010-588-87182 (D.C.); +86-010-588-87191 (J.W.)
| | - Junbo Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China; (A.Z.); (M.C.); (Y.L.); (J.C.)
- School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Correspondence: (D.C.); (J.W.); Tel.: +86-010-588-87182 (D.C.); +86-010-588-87191 (J.W.)
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Zhong A, Shi M. P2.06-010 Association of Vitamin D Receptor BsmI Polymorphism with Lung Cancer Risk: Evidence from a Meta-Analysis. J Thorac Oncol 2017. [DOI: 10.1016/j.jtho.2017.11.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Glycosylation of proteins is an essential process in all eukaryotes. Mucin-type O-linked glycosylation is an evolutionarily conserved protein modification as a kind of glycosylation of proteins. The role of O-glycosylation was well documented in multiple cancers. While in breast cancer, the enzymes that catalyzed the initiation of O-glycosylation remained elusive. In this review, we briefly introduced the process of the initiation of O-glycosylation and summarized the roles of enzymes that catalyzed the initiation step of O-glycosylation in the breast cancer carcinogenesis, development, and progression. Finally, we summarized some attempts exploring the therapy against aberrant O-glycosylation.
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Affiliation(s)
- R Yang
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - H Zhang
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - Y Ma
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - S Gong
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - J Niu
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - J Ma
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
| | - A Zhong
- Department of Respiratory Medicine, Yidu Central Hospital of Weifang, Qingzhou, China
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Amirabadi A, Vidarsson L, Miller E, Sussman MS, Patil K, Gahunia H, Peel SAF, Zhong A, Weiss R, Detzler G, Cheng HLM, Moineddin R, Doria AS. USPIO-related T1 and T2 mapping MRI of cartilage in a rabbit model of blood-induced arthritis: a pilot study. Haemophilia 2014; 21:e59-69. [DOI: 10.1111/hae.12601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2014] [Indexed: 11/27/2022]
Affiliation(s)
- A. Amirabadi
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - L. Vidarsson
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - E. Miller
- Department of Diagnostic Imaging; Children's Hospital for Eastern Ontario; Ottawa ON Canada
| | - M. S. Sussman
- Department of Medical Imaging; Toronto General Hospital; the University Health Network; Toronto ON Canada
| | - K. Patil
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - H. Gahunia
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - S. A. F. Peel
- Department of Oral and Maxillofacial Surgery; Faculty of Dentistry; University of Toronto; Toronto ON Canada
| | - A. Zhong
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - R. Weiss
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - G. Detzler
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - H. L. M. Cheng
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
| | - R. Moineddin
- Department of Family and Community Medicine; University of Toronto; Toronto ON Canada
| | - A. S. Doria
- Department of Diagnostic Imaging; The Hospital for Sick Children; University of Toronto; Toronto ON Canada
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Beggs H, Zhong A, Warren G, Alves O, Brassington G, Pugh T. RAMSSA - An operational, high-resolution, Regional Australian Multi-Sensor Sea surface temperature Analysis over the Australian region. ACTA ACUST UNITED AC 2011. [DOI: 10.22499/2.6101.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Yu XX, Lewin DA, Zhong A, Brush J, Schow PW, Sherwood SW, Pan G, Adams SH. Overexpression of the human 2-oxoglutarate carrier lowers mitochondrial membrane potential in HEK-293 cells: contrast with the unique cold-induced mitochondrial carrier CGI-69. Biochem J 2001; 353:369-75. [PMID: 11139402 PMCID: PMC1221580 DOI: 10.1042/bj3530369] [Citation(s) in RCA: 22] [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: 11/17/2022]
Abstract
Using differential mRNA expression analysis, a previously uncharacterized gene was found to be up-regulated 2-fold in brown adipose tissue (BAT) of mice exposed to cold (4 degrees C) for 48 h. Contig and homology analysis revealed that the gene represents the murine orthologue to a sequence from a public database encoding a putative human protein (CGI-69). The presence of mitochondrial carrier domains in the human protein, its transmembrane topology and cold-induction of the mouse CGI-69 gene in BAT prompted an analysis of the idea that CGI-69 may represent a new uncoupling protein (UCP) functional homologue. However, transfection of human CGI-69 isoforms in HEK-293 cells yielded no change in mitochondrial membrane potential (Deltapsi(m)), despite localization of FLAG-tagged CGI-69 to mitochondria of MCF7 cells. Surprisingly, overexpression of the human 2-oxoglutarate carrier (OGC) protein (originally designed as a negative control) sparked a significant drop in Deltapsi(m), possibly signalling a previously unappreciated uncoupling activity for the OGC.
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Affiliation(s)
- X X Yu
- Department of Endocrinology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
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Yu XX, Mao W, Zhong A, Schow P, Brush J, Sherwood SW, Adams SH, Pan G. Characterization of novel UCP5/BMCP1 isoforms and differential regulation of UCP4 and UCP5 expression through dietary or temperature manipulation. FASEB J 2000; 14:1611-8. [PMID: 10928996 DOI: 10.1096/fj.14.11.1611] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mitochondrial uncoupling proteins have been implicated in the maintenance of metabolic rate and adaptational thermoregulation. We recently reported the identification of a brain-specific mitochondrial uncoupling protein homologue, UCP4. Here we characterized another newly described member of the uncoupling protein family, termed UCP5 (also called BMCP1). UCP5 transcripts are present in multiple human and mouse tissues, with an especially high abundance in the brain and testis. Expression of UCP5 in mammalian cells reduces the mitochondrial membrane potential. Multiple isoforms of UCP5 were identified and exhibited tissue-specific distribution and different potency in reduction of membrane potential. Furthermore, the mRNA abundance of both UCP4 and UCP5 is modulated by nutritional status or temperature in a tissue-specific manner in mice. Brain UCP4 and UCP5 mRNA transcripts rose by 1.5- and 1.7-fold, respectively, and liver UCP5 expression increased by 1.8-fold in response to acute cold exposure. A high-fat diet increased UCP5 mRNA in liver by 1.6-fold selectively in the obesity-resistant A/J but not in the obesity-prone C57BL/6J mouse strain. Liver UCP5 expression decreased significantly with a 24 h fast and was restored to the normal level after refeeding. In contrast, brain transcripts for both genes were not significantly altered by fasting or high-fat diet. These findings are consistent with the notion that UCP4 and UCP5 may be involved in tissue-specific thermoregulation and metabolic changes associated with nutritional status.
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Affiliation(s)
- X X Yu
- Departments of. Endocrinology, Molecular Biology, and. Bioassay and Bioimage, Genentech, Inc., South San Francisco, California 94080, USA
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Hopper RA, Forrest CR, Xu H, Zhong A, He W, Rutka J, Neligan P, Pang CY. Role and mechanism of PKC in ischemic preconditioning of pig skeletal muscle against infarction. Am J Physiol Regul Integr Comp Physiol 2000; 279:R666-76. [PMID: 10938258 DOI: 10.1152/ajpregu.2000.279.2.r666] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 01/10/2023]
Abstract
Protein kinase C (PKC) inhibitors, chelerythrine (Chel, 0.6 mg) and polymyxin B (Poly B, 1.0 mg), and PKC activators, phorbol 12-myristate 13-acetate (PMA, 0.05 mg) and 1-oleoyl-2-acetyl glycerol (OAG, 0.1 mg), were used as probes to investigate the role of PKC in mediation of ischemic preconditioning (IPC) of noncontracting pig latissimus dorsi (LD) muscles against infarction in vivo. These drugs were delivered to each LD muscle flap (8 x 12 cm) by 10 min of local intra-arterial infusion. It was observed that LD muscle flaps sustained 43 +/- 5% infarction when subjected to 4 h of global ischemia and 24 h of reperfusion. IPC with three cycles of 10 min ischemia-reperfusion reduced muscle infarction to 25 +/- 3% (P < 0.05). This anti-infarction effect of IPC was blocked by Chel (42 +/- 7%) and Poly B (37 +/- 2%) and mimicked by PMA (19 +/- 10%) and OAG (14 +/- 5%) treatments (P < 0.05), given 10 min before 4 h of ischemia. In addition, the ATP-sensitive K(+) (K(ATP)) channel antagonist sodium 5-hydroxydecanoate attenuated (P < 0.05) the anti-infarction effect of IPC (37 +/- 2%), PMA (44 +/- 17%), and OAG (46 +/- 9%). IPC, OAG, and Chel treatment alone did not affect mean arterial blood pressure or muscle blood flow assessed by 15-microm radioactive microspheres. Western blot analysis of muscle biopsies obtained before (baseline) and after IPC demonstrated seven cytosol-associated isoforms, with nPKCepsilon alone demonstrating progressive cytosol-to-membrane translocation within 10 min after the final ischemia period of IPC. Using differential fractionation, it was observed that nPKCepsilon translocated to a membrane compartment other than the sarcolemma and/or sarcoplasmic reticulum. Furthermore, IPC and preischemic OAG but not postischemic OAG treatment reduced (P < 0.05) muscle myeloperoxidase activity compared with time-matched ischemic controls during 16 h of reperfusion after 4 h of ischemia. Taken together, these observations indicate that PKC plays a central role in the anti-infarction effect of IPC in pig LD muscles, most likely through a PKC-K(ATP) channel-linked signal-transduction pathway.
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Affiliation(s)
- R A Hopper
- Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
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Weiss GA, Watanabe CK, Zhong A, Goddard A, Sidhu SS. Rapid mapping of protein functional epitopes by combinatorial alanine scanning. Proc Natl Acad Sci U S A 2000; 97:8950-4. [PMID: 10908667 PMCID: PMC16802 DOI: 10.1073/pnas.160252097] [Citation(s) in RCA: 255] [Impact Index Per Article: 10.6] [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: 11/18/2022] Open
Abstract
A combinatorial alanine-scanning strategy was used to determine simultaneously the functional contributions of 19 side chains buried at the interface between human growth hormone and the extracellular domain of its receptor. A phage-displayed protein library was constructed in which the 19 side chains were preferentially allowed to vary only as the wild type or alanine. The library pool was subjected to binding selections to isolate functional clones, and DNA sequencing was used to determine the alanine/wild-type ratio at each varied position. This ratio was used to calculate the effect of each alanine substitution as a change in free energy relative to that of wild type. Only seven side chains contribute significantly to the binding interaction, and these conserved residues form a compact cluster in the human growth hormone tertiary structure. The results were in excellent agreement with free energy data previously determined by conventional alanine-scanning mutagenesis and suggest that this technology should be useful for analyzing functional epitopes in proteins.
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Affiliation(s)
- G A Weiss
- Departments of Protein Engineering, Bioinformatics, and Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
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Billa V, Zhong A, Bargman J, Vas S, Wong PY, Oreopoulos DG. High prevalence of hyperparathyroidism among peritoneal dialysis patients: a review of 176 patients. Perit Dial Int 2000; 20:315-21. [PMID: 10898049] [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: 02/17/2023] Open
Abstract
OBJECTIVES Parathyroid dysfunction continues to produce significant morbidity in dialysis patients. Since the introduction of low calcium dialysate for peritoneal dialysis (PD), no large studies have been done to determine the prevalence of parathyroid dysfunction in these patients. This study was done to assess the prevalence of parathyroid disease in the PD population and to determine the risk factors associated with this dysfunction. DESIGN We analyzed data on 176 patients who received PD at a single center between August 1998 and February 1999. Clinical data, laboratory variables related to parathyroid function, and data pertaining to dialysis treatment and weekly drug dosing were obtained for each patient on two different occasions, approximately 3 months apart. Variables predictive of the development of parathyroid dysfunction were calculated by univariate and multivariate logistic regression analysis. RESULTS Two-thirds of the patients surveyed had an abnormal intact parathyroid hormone (iPTH) level: 47% had an iPTH level more than three times normal, the mean was 54.6+/-35.4 pmol/L; 23% had an iPTH value below the upper limit of normal, here the mean was 3.6+/-1.8 pmol/L. Diabetic patients had lower iPTH levels (22.2+/-28.4 pmol/L) than nondiabetics (33.9+/-34.8 pmol/L) (p = 0.02). On multivariate regression analysis, we found that age, duration of dialysis, Kt/V, serum bicarbonate, and serum ionized calcium levels did not significantly affect parathyroid function. Hyperphosphatemia was the only factor that was associated with the development of secondary hyperparathyroidism in this study population (p = 0.029). CONCLUSION There is a high prevalence of hyperparathyroidism in the current PD population. Phosphate control is suboptimal and hyperphosphatemia is an independent risk factor for the development of hyperparathyroidism.
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Affiliation(s)
- V Billa
- Department of Medicine, University Health Network, University of Toronto, Ontario, Canada
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Zhong A, Billa V, Rotstein LE, Wong PY, Bargman JM, Vas SI, Oreopoulos DG. Recurrence of hyperparathyroidism after total parathyroidectomy and autotransplantation in peritoneal dialysis patients. Perit Dial Int 2000; 20:200-8. [PMID: 10809244] [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] Open
Abstract
OBJECTIVE To evaluate the effectiveness of total parathyroidectomy (PTX) with autotransplantation in the treatment of secondary hyperparathyroidism (HPT), and to assess recurrence rate of HPT in this peritoneal dialysis (PD) population. DESIGN A retrospective study in a single home PD unit. PATIENTS Between 1994 and 1998, 19 of 574 patients on PD underwent PTX for treatment of secondary HPT. MAIN OUTCOME MEASURES Clinical and biochemical improvement, recurrence of HPT, improvement in anemia post-PTX. RESULTS Nineteen (3.3%) patients required PTX between 1994 and 1998. These 5 men and 14 women ranged in age from 22 to 66 years; they had been on maintenance PD pre-PTX for 47.5 +/- 38.1 months, and were followed for 26.1 +/- 15.5 months post-PTX. Sixteen patients had temporary hypocalcemia that was managed by oral (n = 10) or intravenous (n = 6) calcium supplements and calcitriol, while 3 patients had severe "hungry bone" syndrome postoperatively. One patient had recurrent laryngeal nerve palsy post-PTX. Bone pain disappeared in all 12 patients. Pruritus improved in 12/13 patients; fatigue improved in 15/16 patients. Comparison showed significant differences between hemoglobin and hematocrit values 1 month pre-PTX and 12 months post-PTX (p < 0.05). Parathyroid hormone (PTH) level in 15 (79%) patients returned to normal (< or = 7.6 pmol/L) during the first month post-PTX. In 5/12 (42%) patients, PTH level was < or = 7.6 pmol/L 2 years post-PTX, while in 2/12 (17%), PTH was > 22.8 pmol/L (three times normal) 2 years post-PTX, and 3/5 (60%) patients had a PTH > 22.8 pmol/L 3 years post-PTX. CONCLUSIONS Total PTX with autotransplantation is associated with a tendency for recurrence of HPT. Our findings suggest that total PTX with autotransplantation may be an ineffective procedure in controlling HPT over the long term.
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Affiliation(s)
- A Zhong
- Division of Nephrology, The Toronto Hospital and University of Toronto, Ontario, Canada.
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Hu Y, Zhong A, Yang X. [Prognostic value of serum CA125 level in patients with advanced non-small cell lung cancer]. Zhonghua Zhong Liu Za Zhi 2000; 22:30-1. [PMID: 11776591] [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] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To judge the prognostic value of serum CA125 level in patients with advanced non-small cell lung cancer. METHODS Sixty-six untreated patients with advanced non-small cell lung cancer (NSCLC) confirmed histologically were studied. They received two to four cycles of chemotherapy, some of them combined with radiotherapy. All these patients were assayed for serum CA125 before treatment. The cut-off value of serum CA125 level was 35 U/ml. RESULTS Increased serum CA125 levels were observed in 24 out of 66 patients (36.4%). Patients with increased serum CA125 levels had an average survival rate of 12.5% at 1 year and 0 at 2 years, whereas that of patients with normal serum CA125 levels was of 57.1% at 1 years, 14.3% at 2 years and 7.1% at 3 years. Cox proportion hazard multivariate analysis showed that the prognosis of patients was related to serum CA125 levels (P = 0.000) and effects of treatment (P = 0.046). CONCLUSION CA125 can be used as an independent prognostic parameter in advanced NSCLC.
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Affiliation(s)
- Y Hu
- Hubei Cancer Hospital, Wuhan 430079, China
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He W, Zhang J, Zhong A. [Adenosine is effective to improve the viability of the transverse rectus abdominis myocutaneous (TRAM) flap in the pig]. Zhonghua Zheng Xing Shao Shang Wai Ke Za Zhi 1999; 15:444-6. [PMID: 11501082] [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] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
OBJECTIVE The aim of this experiment was to investigate the adenosine treatment for augmentation of TRAM flap viability in pigs. METHODS This TRAM flap model was based on the deep inferior epigastric vascular pedicle, with the center of the transverse skin pedicle attached to the underlying rectus abdominis muscle at the superior end of the muscle and extending bilaterally from its attached muscle. The transverse skin pedicle (6 x 30 cm) included a contralateral and ipsilateral random portion of skin. Prior to raising the TRAM flap, 1 mg, 2 mg or 5 mg adenosine was injected through the superior epigastric artery in the experiment group. RESULTS Treatment with 2 mg or 5 mg adenosine increased skin viability of the transverse skin flap in the experiment group compared with the sham-operated control (P < 0.05, n = 5). CONCLUSION Adenosine treatment through a dominant vascular pedicle prior to raising the TRAM flap is effective in augmenting skin viability of the flap.
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Affiliation(s)
- W He
- Plastic Surgery Hospital of Chinese Academy of Medical Sciences, Beijing, 100041
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He W, Zhang J, Zhong A. [Acute ischemic preconditioning protects against skeletal muscle infarction in the pig]. Zhonghua Zheng Xing Shao Shang Wai Ke Za Zhi 1999; 15:348-50. [PMID: 11501096] [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] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
OBJECTIVE The aim of this study was to investigate metabolism of ischemic muscle and the efficacy of acute ischemic preconditioning for protection of skeletal muscles against infarction. METHODS The efficacy of preconditioning was tested by subjecting pig latissimus dorsi muscle to 3 cycles of ischemia reperfusion, each for 10 min, before 4 h of global ischemia. Infarction was assessed at 48 h reperfusion using nitroblue tetrazolium dye. Muscle biopsies were taken from the latissimus dorsi before ischemia, at the end of 2 and 4 h of ischemia and 1.5 h of reperfusion. RESULTS Preconditioning reduced the total infarct size by 44% in the latissimus dorsi. The muscle contents of ATP were maintained higher and the lactate lower (P < 0.05) in the preconditioned than in the non-preconditioned muscle at the end of 2 h, 4 h of ischemia and 1.5 h of reperfusion. CONCLUSION Preconditioning of pig skeletal muscle is associated with a lower energy metabolism during sustained ischemia. At the present time, it is not known if this energy sparing effect is a major mechanism of ischemia preconditioning against infarction in the skeletal muscle.
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Affiliation(s)
- W He
- Plastic Surgery Hospital of Chinese Academy of Medical Sciences, Beijing 100041
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Mao W, Yu XX, Zhong A, Li W, Brush J, Sherwood SW, Adams SH, Pan G. UCP4, a novel brain-specific mitochondrial protein that reduces membrane potential in mammalian cells. FEBS Lett 1999; 443:326-30. [PMID: 10025957 DOI: 10.1016/s0014-5793(98)01713-x] [Citation(s) in RCA: 269] [Impact Index Per Article: 10.8] [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: 10/17/2022]
Abstract
Uncoupling proteins (UCPs) are a family of mitochondrial transporter proteins that have been implicated in thermoregulatory heat production and maintenance of the basal metabolic rate. We have identified and partially characterized a novel member of the human uncoupling protein family, termed uncoupling protein-4 (UCP4). Protein sequence analyses showed that UCP4 is most related to UCP3 and possesses features characteristic of mitochondrial transporter proteins. Unlike other known UCPs, UCP4 transcripts are exclusively expressed in both fetal and adult brain tissues. UCP4 maps to human chromosome 6p11.2-q12. Consistent with its potential role as an uncoupling protein, UCP4 is localized to the mitochondria and its ectopic expression in mammalian cells reduces mitochondrial membrane potential. These findings suggest that UCP4 may be involved in thermoregulatory heat production and metabolism in the brain.
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Affiliation(s)
- W Mao
- Department of Endocrinology, Genentech, Inc., South San Francisco, CA 94080, USA
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Pang CY, Neligan P, Zhong A, He W, Xu H, Forrest CR. Effector mechanism of adenosine in acute ischemic preconditioning of skeletal muscle against infarction. Am J Physiol 1997; 273:R887-95. [PMID: 9321864 DOI: 10.1152/ajpregu.1997.273.3.r887] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We used adenosine A1 receptor agonist N6-1(phenyl-2R-isopropyl)-adenosine (PIA), A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), and ATP-sensitive K+ (KATP) channel blockers sodium 5-hydroxydecanoate (5-HD) and glibenclamide (Glib), as probes to investigate the role and mechanism of adenosine in ischemic preconditioning (IPC) of noncontractile skeletal muscle against infarction, using the pig latissimus dorsi muscle flap model. Except for Glib, all drugs were delivered to each muscle flap by 10-min local intra-arterial infusion to avoid systemic effects. Muscle flaps that were subjected to 4 h of global ischemia and 48 h of reperfusion sustained 40 +/- 2% infarction. IPC with three cycles of 10 min ischemia and reperfusion, preischemic adenosine, or PIA treatment reduced (P < 0.05) muscle infarction to 24 +/- 2, 18 +/- 2, and 24 +/- 2%, respectively. The anti-infarction effect of IPC and adenosine was blocked by DPCPX, 5-HD, and Glib (P < 0.05). Preischemic adenosine treatment also maintained higher muscle contents of phosphocreatine, ATP, and energy charge potential and lower muscle contents of dephosphorylated metabolites and lactate during ischemia and a lower muscle myeloperoxidase (MPO) activity during reperfusion compared with the control (P < 0.05). Preischemic adenosine treatment did not increase muscle content of adenosine during ischemia or reperfusion. Furthermore, adenosine given at the onset of reperfusion was not effective in attenuating muscle MPO activity or infarction. Taken together, these observations indicate that adenosine, through A1 receptors, initiates the mechanism of IPC with postreceptor involvement of KATP channels in skeletal muscle. However, adenosine is unlikely to play a key role in the effector mechanism. Presently, the cause and role of energy sparing and neutrophil inhibitory effects associated with the anti-infarction effect of preischemic adenosine treatment are unknown.
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Affiliation(s)
- C Y Pang
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Pang CY, Neligan P, Xu H, He W, Zhong A, Hopper R, Forrest CR. Role of ATP-sensitive K+ channels in ischemic preconditioning of skeletal muscle against infarction. Am J Physiol 1997; 273:H44-51. [PMID: 9249473 DOI: 10.1152/ajpheart.1997.273.1.h44] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We studied the role and mechanism of ATP-sensitive K+ (KATP) channels in ischemic preconditioning (IPC) of skeletal muscle against infarction in vivo. Surgically denervated, noncontractile latissimus dorsi muscle flaps in pentobarbitone-anesthetized pigs were assigned to nine groups: control; IPC (3 cycles of 10-min ischemia/reperfusion); preischemic lemakalim (LMK, 0.18 mg/muscle); postischemic LMK; sodium 5-hydroxydecanoate (5-HD, 27 mg/muscle) before IPC; glibenclamide (Glib 0.3 mg/kg iv) before IPC; 5-HD before preischemic LMK; 5-HD before ischemia; and Glib before ischemia. Except for Glib, all drugs were delivered to each muscle by 10-min local intraarterial infusion to avoid systemic effects. All muscle flaps underwent 4 h of global ischemia. Infarction was assessed at 48 h of reperfusion. In a separate study, muscle biopsies were taken before, during, and after ischemia for assay of high-energy phosphate and lactate contents and myeloperoxidase (MPO) activity. It was observed that muscle infarction in the IPC (24 +/- 2%) and preischemic LMK (21 +/- 2%) groups were smaller (P < 0.05) than that in the control (42 +/- 2%). The anti-infarction effect of IPC and LMK was blocked by 5-HD or Glib. IPC and preischemic LMK caused a higher (P < 0.05) muscle content of ATP and energy charge potential, a lower (P < 0.05) muscle content of lactate during ischemia, and a lower (P < 0.05) muscle MPO activity throughout 16 h of reperfusion compared with the control. These observations indicated for the first time that KATP channels are also involved in the anti-infarction effect of IPC in noncontractile skeletal muscle in vivo. Presently, the cause and importance of energy-sparing and neutrophil-inhibitory effects of IPC and LMK are not known.
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Affiliation(s)
- C Y Pang
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Forrest CR, Neligan P, Zhong A, He W, Yang RZ, Pang CY. Acute adenosine treatment is effective in augmentation of ischemic tolerance in muscle flaps in the pig. Plast Reconstr Surg 1997; 99:172-82. [PMID: 8982201 DOI: 10.1097/00006534-199701000-00026] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [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: 02/03/2023]
Abstract
The objective of the present project was to investigate the efficacy and mechanism of acute (10-minute) adenosine treatment for augmentation of ischemic tolerance in muscle flaps in pigs. Varying doses of adenosine were infused into 28 latissimus dorsi muscle flaps through the axillary artery (0, 0.5, or 2.0 mg per flap) and 22 gracilis muscle flaps through the medial circumflex femoral artery (0, 10, or 20 mg per flap) over 10 minutes. Ten minutes after adenosine infusion, these muscle flaps were subjected to 4 hours of sustained warm global ischemia. In addition, one group of latissimus dorsi muscle flaps (n = 6) received a 10-minute intraarterial adenosine infusion (0.5 mg) at the beginning of reperfusion. Muscle biopsies (n = 4 or 5) for adenosine triphosphate (ATP) analysis were obtained before and after adenosine infusion and at the end of 4 hours of ischemia. The extent of muscle infarction was assessed at 48 hours of reperfusion by the tetrazolium dye staining technique. Muscle blood flow in latissimus dorsi muscle flaps was measured at the end of adenosine infusion (0 or 0.5 mg per flap, n = 8) by the radioactive microsphere (15-microns) technique. It was observed that adenosine, at all doses tested, significantly (p < 0.05) reduced the extent of muscle infarction in latissimus dorsi muscle flaps (control, 40.3 +/- 2.2 percent; 0.5 mg, 20.6 +/- 1.6 percent; 2.0 mg, 18.2 +/- 1 percent) and gracilis muscle flaps (control, 31.0 +/- 1.5 percent; 10 mg, 14.3 +/- 3 percent; 20 mg, 11.6 +/- 1.2 percent). Preischemic adenosine treatment (0.5 mg per flap) was associated with maintenance of a significantly (p < 0.05) higher muscle content of ATP in latissimus dorsi muscle flaps at the end of 4 hours of ischemia compared with saline-treated ischemic controls. Postischemic adenosine treatment did not protect latissimus dorsi muscle flaps against infarction. Furthermore, adenosine treatment did not have any significant effect on mean systemic arterial blood pressure or muscle blood flow in latissimus dorsi muscle flaps. It is concluded that acute (10-minute) preischemic adenosine treatment is effective in augmentation of ischemic tolerance in muscle flaps and that this protective effect of adenosine may be, at least in part, the result of slowing muscle ATP depletion during sustained ischemia. The possible mechanisms of this adenosine-induced energysparing effect are discussed.
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Affiliation(s)
- C R Forrest
- Division of Surgical Research, Hospital for Sick Children, Toronto, Ontario, Canada
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Pang CY, Yang RZ, Neligan P, Xu N, Chiu C, Zhong A, Forrest CR. Vascular effects and mechanism of action of endothelin-1 in isolated perfused pig skin. J Appl Physiol (1985) 1995; 79:2106-13. [PMID: 8847280 DOI: 10.1152/jappl.1995.79.6.2106] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [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: 02/02/2023] Open
Abstract
We investigated the vascular effects and mechanism of action of endothelin-1 (ET-1) in the skin by intra-arterial infusion of ET-1 and its precursor Big ET-1 via a direct cutaneous artery in isolated perfused pig skin flaps (6 x 16 cm). The vascular contractivity was studied by monitoring the perfusion pressure in the skin flap. There was evidence to indicate local conversion of Big ET-1 to ET-1 in the pig skin. It was also observed that ET-1 was a potent long-lasting vasoconstrictor with a potency of approximately 10- and 300-fold higher than those of Big ET-1 and norepinephrine, respectively. The vasoconstrictor action of ET-1 was blocked (P < 0.01) by a selective ETA-receptor antagonist (BQ-123 or BQ-610; 10(-7) M) and enhanced (P < 0.05) by a nitric oxide synthase inhibitor (NG-monomethyl-L-arginine or N omega-nitro-L-arginine methyl ester; 10(-5) M). ET-1-induced increase in perfusion pressure was attenuated (P < 0.05) by an L-type Ca(2+)-channel antagonist (nitrendipine, verapamil, or nifedipine; 10(-5) M) and by removal of Ca2+ from the perfusate. ET-1-induced increase in perfusion pressure was also attenuated (P < 0.05) by a phospholipase C inhibitor (neomycin; 10(-2) M), a protein kinase C (PKC) inhibitor (chelerythrine or H-7; 10(-5) M), and an intracellular Ca2+ chelator [1,2-bis(2-aminophenoxy)]ethane-N,N,N',N'-tetraacetic acid (BAPTA); 10(-5) M]. Furthermore, it was observed that the concentration-dependent (5 x 10(-8) to 10(-5) M) increase in perfusion pressure induced by phorbol 12,13-dibutyrate, a PKC activator, was not affected by verapamil (10(-5) M) or removal of Ca2+ from the perfusate. Taken together, these observations suggest that the vasoconstrictor mechanism of ET-1 in the pig skin involved activation of ETA receptors, L-type Ca2+ channels, phospholipase C, and PKC and that the vasoconstrictor effect caused by activation of PKC was independent of L-type Ca2+ channels.
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Affiliation(s)
- C Y Pang
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
OBJECTIVE The aims were to investigate the efficacy of acute ischaemic preconditioning for protection of skeletal muscles against infarction and its effect on muscle blood flow and ischaemic muscle metabolism. METHODS The efficacy of preconditioning was tested by subjecting pig latissimus dorsi and gracilis muscles to different numbers and durations of ischaemia/reperfusion cycles before 4 h of global ischaemia. Infarction was assessed at 48 h of reperfusion, using nitroblue tetrazolium dye. Blood flow in the latissimus dorsi was measured at the end of preconditioning and 1.5 and 3.0 h of reperfusion, using the radioactive microsphere (15 microns) technique. Muscle biopsies were taken from the latissimus dorsi before ischaemia, at the end of 2 and 4 h of ischaemia, and 1.5 h of reperfusion. RESULTS At least three cycles of 10 min ischaemia and 10 min reperfusion were required for preconditioning of latissimus dorsi and gracilis muscles for protection against infarction. Preconditioning reduced the total infarct size by 44% and 62% in latissimus dorsi and gracilis muscles, respectively. Preconditioning did not affect preischaemia muscle blood flow but it reduced the muscle content (preischaemia reserve) of phosphocreatine and ATP and the muscle energy charge potential (ECP) by 13.5%*, 27.5%*, and 8%* (*P < 0.05), respectively. In spite of a lower preischaemia reserve of phosphocreatine and ATP, the muscle contents of phosphocreatine and ATP and muscle ECP were maintained higher and the lactate lower (*P < or = 0.05) in the preconditioned than in the non-preconditioned (control) muscles at the end of 4 h of ischaemia [phosphocreatine 8.0(SEM 0.4) v 3.2(0.3)*; ATP 9.8(0.7) v 7.8(0.3); ECP 0.72(0.02) v 0.66(0.01)*; lactate 115.4(8.6) v 160.5(11.8)* mumol.g-1 dry muscle]. The level of ATP and ECP also remained significantly higher and the level of lactate significantly lower in the preconditioned than in the non-preconditioned latissimus dorsi muscles at 1.5 h of reperfusion. Hyperaemia was seen in the preconditioned latissimus dorsi muscles at 1.5 h of reperfusion and it subsided by the end of 3h of reperfusion. CONCLUSIONS The protective effect of preconditioning can be induced in pig skeletal muscle but at a higher threshold than reported previously in pig cardiac muscle (one cycle). Preconditioning of pig skeletal muscle is associated with a lower energy metabolism during sustained ischaemia. At the present time, it is not known if this energy sparing effect is a major mechanism of ischaemic preconditioning against infarction in skeletal muscles.
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Affiliation(s)
- C Y Pang
- Research Institute, Hospital for Sick Children, University of Toronto, Ontario, Canada
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Morris SF, Pang CY, Zhong A, Boyd B, Forrest CR. Assessment of ischemia-induced reperfusion injury in the pig latissimus dorsi myocutaneous flap model. Plast Reconstr Surg 1993; 92:1162-72. [PMID: 8234514 DOI: 10.1097/00006534-199311000-00026] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [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: 01/29/2023]
Abstract
Experiments were conducted to assess ischemia-induced reperfusion injury in the pig latissimus dorsi myocutaneous flap model. Forty Yorkshire pigs (19.5 +/- 0.6 kg) were assigned to groups A, B, C, and D (n = 10 pigs). Bilateral 8 x 13 cm latissimus dorsi myocutaneous flaps were constructed in each pig, and one flap was assigned to ischemic treatment and the contralateral flap served as a nonischemic control. The treatment flaps in groups A, B, C, and D were subjected to 2, 4, 6, and 8 hours of warm global ischemia, respectively. Pigs in groups A, B, C, and D were divided into two subgroups (n = 5 pigs), and extents of skin and muscle necrosis in control and treatment flaps were assessed with the fluorescein and nitroblue tetrazolium dye stain tests, respectively, after 2 and 7 days of reperfusion. Significantly (p < 0.01) greater extents of skin and muscle necrosis were observed in latissimus dorsi myocutaneous flaps subjected to 4, 6, or 8 hours of ischemia compared with their contralateral controls. Extents of skin and muscle necrosis also increased significantly (p < 0.01) with increases in ischemia time in treatment flaps. Of particular importance was the observation that there was no significant difference in the extent of skin or muscle necrosis between 2 and 7 days of reperfusion in all control and treatment groups. This observation indicates that 2 days of reperfusion time is adequate to assess the maximum extent of skin and muscle ischemia-induced reperfusion injury in pig latissimus dorsi myocutaneous flaps. Furthermore, it was observed that 1-cm segments of latissimus dorsi muscle were not too thick to allow the use of the nitroblue tetrazolium dye stain test for assessment of muscle viability, as judged by the highly correlated (r = 0.98, n = 40) linear relationship between assessment of muscle viability from one transverse cut surface of muscle segments and by weighing total viable and nonviable muscles dissected from the flaps according to the nitroblue tetrazolium dye stain on both transverse cut surfaces. It is important to note that the maximum length of the latissimus dorsi myocutaneous flap model for ischemia-induced reperfusion injury research should not exceed the maximum length of skin viability in the nonischemic control in order to avoid the complication of skin necrosis due to excessive length of skin.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S F Morris
- Division of Surgical Research, Hospital for Sick Children, Toronto, Ontario, Canada
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Dorion D, Zhong A, Chiu C, Forrest CR, Boyd B, Pang CY. Role of xanthine oxidase in reperfusion injury of ischemic skeletal muscles in the pig and human. J Appl Physiol (1985) 1993; 75:246-55. [PMID: 8397177 DOI: 10.1152/jappl.1993.75.1.246] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [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: 01/30/2023] Open
Abstract
We investigated whether xanthine oxidase (XO) is a major source of oxygen-derived free radicals (oxy-radicals) in the pig and human skeletal muscles. It was observed that xanthine dehydrogenase and XO activities in nonischemic pig latissimus dorsi (LD) and gracilis muscles and human LD and rectus abdominis (RA) muscles were < 0.5 mU/g wet wt. The pig LD muscle hypoxanthine content increased significantly from 0.33 +/- 0.02 to 2.33 +/- 0.44 mumol/g dry wt after 5 h of warm ischemia, but the muscle uric acid content remained unchanged up to 2 h of reperfusion. Similarly, the hypoxanthine content in the human LD and RA muscles increased from 0.33 +/- 0.03 to 0.84 +/- 0.23 mumol/g dry wt after 2.0-3.5 h of warm ischemia, and the muscle uric acid content remained unchanged at the end of 15-90 min of reperfusion. Furthermore, 5 days of allopurinol treatment (25 mg/kg iv twice daily) starting 2 days before ischemia or 3 days of oxypurinol treatment (25 mg/kg iv twice daily) starting 15 min before reperfusion did not attenuate the extent of skeletal muscle necrosis in pig LD muscles subjected to 5 h of ischemia and 48 h of reperfusion. However, deferoxamine treatment (250 mg/kg iv twice daily) starting before or after ischemia, as described above, significantly reduced the extent of pig LD muscle necrosis. Finally, at 2 and 48 h of reperfusion significantly higher muscle neutrophil contents were seen in ischemic than in nonischemic control pig LD muscles. Neutrophil depletion with mechlorethamine (0.75 mg/kg iv) significantly reduced the extent of necrosis in pig LD muscles. These observations indicate that XO is not a major source of oxy-radicals in ischemia/reperfusion injury in the pig gracilis and LD muscles and human RA and LD muscles.
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Affiliation(s)
- D Dorion
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
Ischemic necrosis resulting from vasospasm is a common complication in skin flap surgery, and serotonin released by traumatized platelets is likely to play an important role in the pathogenesis of skin vasospasm in flap surgery. We studied the pathogenic role of serotonin and its pharmacologic intervention thereof in skin flap ischemic necrosis in pigs. We observed that serotonin caused a concentration-dependent (10(-8)-10(-5) M) increase in perfusion pressure in isolated perfused pig skin flaps. This vasoconstrictive effect of serotonin was blocked by S1C/2-serotonergic receptor antagonists LY53857 (10(-5) M) and ketanserin (10(-5) M), but not by an alpha 1-adrenoceptor antagonist (prazosin 10(-5) M), or a thromboxane A2 (TxA2)/endoperoxide receptor antagonist (SQ30741 10(-5) M). The vasoconstrictive effect of serotonin was more pronounced (p < 0.05) in the presence of an endothelium-derived nitric oxide (NO) synthesis inhibitor [N omega-monomethyl-L-arginine (L-NA) or NG-nitro-L-arginine (L-NMMA) 10(-5) M] but not a cyclooxygenase inhibitor (indomethacin 10(-5) M). In in vivo studies, serotonin infusion (5 micrograms/kg/min intravenously, i.v.) significantly (p < 0.05) decreased pig random pattern skin flap capillary blood flow. This in vivo vascular effect was also completely blocked in pigs pretreated with LY53857 (0.4 mg/kg i.v.). In a separate experiment without serotonin infusion, i.v. prazosin (2-8 micrograms/kg), dazmegrel (2-6 mg/kg), or SQ30741 (2-4 mg/kg) had no significant effect on skin flap capillary blood flow as compared with control. On the other hand, i.v. sergolexole or LY53857 significantly (p < 0.05) increased skin flap capillary blood flow in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Y Pang
- Hospital for Sick Children, Department of Physiology, University of Toronto, Ontario, Canada
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Abstract
Three experiments were conducted to study the effect of ketanserin and LY53857, S2-serotonergic receptor antagonists, on skin blood flow and viability in acute random pattern skin flaps (4 x 10 cm) in the pig. In experiment 1, the dose-response effect of intravenous ketanserin (0, 0.15, 0.25, 0.35, and 0.50 mg/kg) on skin flap capillary blood flow was studied 6 hr after skin flap surgery, using the radioactive microsphere (15 microns) technique and under pentobarbital anesthesia. Significant (P less than 0.05) increase in skin flap blood flow was seen at the dosages of 0.25 and 0.35 mg/kg compared with the saline-treated control. In experiment 2, the effect of five-day intramuscular ketanserin and LY53857 treatment (0.30 mg/kg/day; in divided doses) on skin flap viability was studied. The drug treatments were started two days preoperatively. It was observed that the length of skin flap viability in ketanserin (6.6 +/- 0.2 cm; n = 40 flaps) and LY53857 (6.8 +/- 0.3 cm; n = 40 flaps) treated flaps were significantly (P less than 0.05) higher than the saline-treated control (5.5 +/- 0.1 cm; n = 48 flaps). Ketanserin treatment started 30 min after flap surgery also significantly (P less than 0.05) increased the length of skin flap viability (6.1 +/- 0.1 cm) compared with the control. There was no significant difference in skin viability between ketanserin and LY53857 treated skin flaps. The preceding study on the effect of ketanserin treatment on random pattern skin flap viability was repeated in experiment 3. Again, it was observed that intramuscular ketanserin treatment significantly (P less than 0.05) increased the skin flap viability. It was concluded that ketanserin and LY53857 treatment resulted in significant augmentation of porcine acute random pattern skin flap viability. This is the first experimental evidence to indicate that S2-serotonergic receptors participate in the pathogenesis of skin flap ischemia.
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Affiliation(s)
- A Zhong
- Division of Surgical Research, Hospital for Sick Children, Toronto, Ontario, Canada
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