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Zhao C, Wang Y, Chen C, Zhu Y, Miao Z, Mou X, Yuan W, Zhang Z, Li K, Chen M, Liang W, Zhang M, Miao W, Dong Y, Deng D, Wu J, Ke B, Bao R, Geng J. Direct and Continuous Monitoring of Multicomponent Antibiotic Gentamicin in Blood at Single-Molecule Resolution. ACS NANO 2024; 18:9137-9149. [PMID: 38470845 DOI: 10.1021/acsnano.4c00302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Point-of-care monitoring of small molecules in biofluids is crucial for clinical diagnosis and treatment. However, the inherent low degree of recognition of small molecules and the complex composition of biofluids present significant obstacles for current detection technologies. Although nanopore sensing excels in the analysis of small molecules, the direct detection of small molecules in complex biofluids remains a challenge. In this study, we present a method for sensing the small molecule drug gentamicin in whole blood based on the mechanosensitive channel of small conductance in Pseudomonas aeruginosa (PaMscS) nanopore. PaMscS can directly detect gentamicin and distinguish its main components with only a monomethyl difference. The 'molecular sieve' structure of PaMscS enables the direct measurement of gentamicin in human whole blood within 10 min. Furthermore, a continuous monitoring device constructed based on PaMscS achieved continuous monitoring of gentamicin in live rats for approximately 2.5 h without blood consumption, while the drug components can be analyzed in situ. This approach enables rapid and convenient drug monitoring with single-molecule level resolution, which can significantly lower the threshold for drug concentration monitoring and promote more efficient drug use. Moreover, this work also lays the foundation for the future development of continuous monitoring technology with single-molecule level resolution in the living body.
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Affiliation(s)
- Changjian Zhao
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Yu Wang
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Chen Chen
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Yibo Zhu
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Zhuang Miao
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Centre of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xingyu Mou
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Weidan Yuan
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Zhihao Zhang
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Kaiju Li
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Mutian Chen
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Weibo Liang
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Ming Zhang
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Wenqian Miao
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yuhan Dong
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
| | - Dong Deng
- Division of Obstetrics, Key Laboratory of Birth Defects and Related Disease of Women and Children of MOE, State Key Laboratory of Biotherapy, West China Second Hospital, Sichuan University, Chengdu, Sichuan, 610041 China
| | - Jianping Wu
- Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Bowen Ke
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Centre of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Rui Bao
- Center of Infectious Diseases, Division of Infectious Diseases in State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Jia Geng
- Department of Laboratory Medicine, State Key Laboratory of Biotherapy and Clinical Laboratory Medicine Research Center, West China Hospital, Sichuan University, Chengdu, 610041, China
- Tianfu Jincheng Laboratory, City of Future Medicine, Chengdu 610500, China
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Campbell NWC, Patel SH, Ferrandi P, Couture S, Farino DO, Stout J, Sabbaghi A, Carroll CC. Impact of essential amino acid intake, resistance exercise, and aging on the concentration of Achilles peritendinous amino acids and procollagen Iα1 in humans. Amino Acids 2023:10.1007/s00726-023-03268-3. [PMID: 37129720 DOI: 10.1007/s00726-023-03268-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/12/2023] [Indexed: 05/03/2023]
Abstract
Recent studies have shown that consuming amino acid-rich compounds improves tendon collagen content and biomechanical properties. Yet, it is unclear if the consumption of amino acids alters local (peritendinous) amino acid concentrations. If aging or exercise influence local amino acid concentrations in conjunction with an amino acid bolus is also not known. We conducted two studies. In Study 1, young women (n = 7, 25 ± 2 years) completed two identical resistance training sessions with either essential amino acid (EAA) or placebo consumption. In Study 2, an EAA bolus identical to Study 1 was given to younger (n = 7; 27 ± 1 year) and older adults (n = 6; 68 ± 2 years). Microdialysis was used to determine Achilles peritendinous amino acid and pro-collagen Iα1 (a marker of collagen synthesis) concentrations. In Study 1, amino acid consumption increased peritendinous concentrations of all EAA except histidine (p < 0.05). In Study 2, the peritendinous concentration of EAAs except for methionine, histidine, and lysine (p > 0.05) increased with time (p < 0.05). Further, the concentrations of most measured amino acids were greater in older adults (p < 0.05). Pro-collagen Iα1 concentration (p > 0.05) was unaffected by exercise, EAA, or aging (p > 0.05). Our findings demonstrate the following: (1) when not combined with exercise, an oral EAA bolus leads to only modest increases in Achilles peritendinous amino acid concentrations; (2) when combined with resistance exercise, EAA consumption resulted in greater peritendinous amino acid concentrations compared to no exercise; (3) the basal concentrations of most amino acids were greater in older adults, and (4) neither the EAA bolus nor exercise altered peritendinous pro-collagen concentrations.
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Affiliation(s)
- Nathan W C Campbell
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA
| | - Shivam H Patel
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA
| | - Peter Ferrandi
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA
| | - Samantha Couture
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA
| | - Dominick O Farino
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA
| | - Julianne Stout
- College of Veterinary Medicine, Purdue University, 625 Harrison St, West Lafayette, IN, 47907, USA
| | - Arman Sabbaghi
- Department of Statistics, Purdue University, 250 N University St, West Lafayette, IN, 47907, USA
| | - Chad C Carroll
- Department of Health and Kinesiology, Purdue University, 800 W. Stadium Ave, West Lafayette, IN, 47907, USA.
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Abstract
Coxiella burnetii, the causative agent of query (Q) fever in humans, is an obligate intracellular bacterium. C. burnetii can naturally infect a broad range of host organisms (e.g., mammals and arthropods) and cell types. This amphotropic nature of C. burnetii, in combination with its ability to utilize both glycolytic and gluconeogenic carbon sources, suggests that the pathogen relies on metabolic plasticity to replicate in nutritionally diverse intracellular environments. To test the significance of metabolic plasticity in C. burnetii host cell colonization, C. burnetii intracellular replication in seven distinct cell lines was compared between a metabolically competent parental strain and a mutant, CbΔpckA, unable to undergo gluconeogenesis. Both the parental strain and CbΔpckA mutant exhibited host cell-dependent infection phenotypes, which were influenced by alterations to host glycolytic or gluconeogenic substrate availability. Because the nutritional environment directly impacts host cell physiology, our analysis was extended to investigate the response of C. burnetii replication in mammalian host cells cultivated in a novel physiological medium based on the nutrient composition of mammalian interstitial fluid, interstitial fluid-modeled medium (IFmM). An infection model based on IFmM resulted in exacerbation of a replication defect exhibited by the CbΔpckA mutant in specific cell lines. The CbΔpckA mutant was also attenuated during infection of an animal host. Overall, the study underscores that gluconeogenic capacity aids C. burnetii amphotropism and that the amphotropic nature of C. burnetii should be considered when resolving virulence mechanisms in this pathogen.
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Costa DM, Cruz-Filho JD, Vasconcelos ABS, Gomes-Santos JV, Reis LC, de Lucca W, Camargo EA, Lauton-Santos S, Zanon NM, Kettelhut ÍDC, Navegantes LC, Mecawi ADS, Badauê-Passos D, Lustrino D. Oxytocin induces anti-catabolic and anabolic effects on protein metabolism in the female rat oxidative skeletal muscle. Life Sci 2021; 279:119665. [PMID: 34087281 DOI: 10.1016/j.lfs.2021.119665] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 11/26/2022]
Abstract
AIMS Although it is well established that skeletal muscle contains oxytocin (OT) receptors and OT-knockout mice show premature development of sarcopenia, the role of OT in controlling skeletal muscle mass is still unknown. Therefore, the present work aimed to determine OT's effects on skeletal muscle protein metabolism. MAIN METHODS Total proteolysis, proteolytic system activities and protein synthesis were assessed in isolated soleus muscle from prepubertal female rats. Through in vivo experiments, rats received 3-day OT treatment (3UI.kg-1.day-1, i.p.) or saline, and muscles were harvested for mass-gain assessment. KEY FINDINGS In vitro OT receptor stimulation reduced total proteolysis, specifically through attenuation of the lysosomal and proteasomal proteolytic systems, and in parallel activated the Akt/FoxO1 signaling and suppressed atrogenes (e.g., MuRF-1 and atrogin-1) expression induced by motor denervation. On the other hand, the protein synthesis was not altered by in vitro treatment with the OT receptor-selective agonist. Although short-term OT treatment did not change the atrogene mRNA levels, the protein synthesis was stimulated, resulting in soleus mass gain, probably through an indirect effect. SIGNIFICANCE Taken together, these data show for the first time that OT directly inhibits the proteolytic activities of the lysosomal and proteasomal systems in rat oxidative skeletal muscle by suppressing atrogene expression via stimulation of Akt/FoxO signaling. Moreover, the data obtained from in vivo experiments suggest OT's ability to control rat oxidative skeletal muscle mass.
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Affiliation(s)
- Daniely Messias Costa
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - João da Cruz-Filho
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Alan Bruno Silva Vasconcelos
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - João Victor Gomes-Santos
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Luis Carlos Reis
- Department of Physiological Sciences, Center for Biological and Health Sciences, Rural Federal University of Rio de Janeiro, Seropédica, RJ, Brazil
| | - Waldecy de Lucca
- Department of Morphology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Enilton Aparecido Camargo
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Sandra Lauton-Santos
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Neusa Maria Zanon
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - Ísis do Carmo Kettelhut
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - Luiz Carlos Navegantes
- Department of Physiology and Biochemistry & Immunology, Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, SP, Brazil
| | - André de Souza Mecawi
- Department of Biophysics, São Paulo Medical School, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Daniel Badauê-Passos
- Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil
| | - Danilo Lustrino
- Graduate Program in Physiological Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil; Department of Physiology, Center for Biological and Health Sciences, Federal University of Sergipe, São Cristóvão, SE, Brazil.
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Zalivskaya A, Fadeeva D, Shestopalova N, Avtina N, Radyukova V, Ivanova V. Comparative characteristics of gel bases for semisolid dosage forms. BIO WEB OF CONFERENCES 2021. [DOI: 10.1051/bioconf/20214003008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The article provides an overview of modern data on the main gel bases used in the technology of semisolid dosage forms. The main classes of gelling substances are characterized. According to data, the choice of excipient must be justified from the point of view of the physicochemical properties of the active substance, and depends on the place of application of the gel.
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Evaluation of Intrahepatic Lactate/Pyruvate Ratio As a Marker for Ischemic Complications Early After Liver Transplantation-A Clinical Study. Transplant Direct 2020; 5:e505. [PMID: 32095500 PMCID: PMC7004593 DOI: 10.1097/txd.0000000000000952] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/25/2019] [Indexed: 12/04/2022] Open
Abstract
Background. Lactate/pyruvate ratio has been introduced as a sensitive marker for ischemia in the transplanted liver. In the present study, we aimed to evaluate lactate/pyruvate ratio measured in the liver by microdialysis as a marker for ischemic complications early after liver transplantation. Methods. Forty-five patients undergoing liver transplantation were included in the study. A microdialysis catheter was placed in the liver graft directly following liver transplantation and the metabolites lactate and pyruvate measured for up to 6 days and the lactate/pyruvate ratio calculated. The association between increased intrahepatic lactate/pyruvate ratio and ischemic complications was studied. Results. One of 45 patients developed hepatic arterial thrombosis. Forty-four events with increased lactate/pyruvate ratio were identified in 24 patients. In none of the 24 patients that had a raised lactate/pyruvate ratio could we detect occurrence of any ischemic complication. In the patient that did have hepatic arterial thrombosis, the lactate/pyruvate ratio did not show a significant prolonged rise. Conclusions. An increase in the intrahepatic lactate/pyruvate ratio is not necessarily indicative of ischemic complications and is thus not a reliable marker for monitoring of clinically significant ischemia in the liver early after transplantation.
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McCormack WG, Cooke JP, O’Connor WT, Jakeman PM. Dynamic measures of skeletal muscle dialysate and plasma amino acid concentration in response to exercise and nutrient ingestion in healthy adult males. Amino Acids 2016; 49:151-159. [DOI: 10.1007/s00726-016-2343-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 09/29/2016] [Indexed: 12/01/2022]
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Carson BP, McCormack WG, Conway C, Cooke J, Saunders J, O’Connor WT, Jakeman PM. An in vivo microdialysis characterization of the transient changes in the interstitial dialysate concentration of metabolites and cytokines in human skeletal muscle in response to insertion of a microdialysis probe. Cytokine 2015; 71:327-33. [DOI: 10.1016/j.cyto.2014.10.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 07/18/2014] [Accepted: 10/28/2014] [Indexed: 01/16/2023]
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Abstract
Carnosine (β-alanyl-l-histidine) was discovered in 1900 as an abundant non-protein nitrogen-containing compound of meat. The dipeptide is not only found in skeletal muscle, but also in other excitable tissues. Most animals, except humans, also possess a methylated variant of carnosine, either anserine or ophidine/balenine, collectively called the histidine-containing dipeptides. This review aims to decipher the physiological roles of carnosine, based on its biochemical properties. The latter include pH-buffering, metal-ion chelation, and antioxidant capacity as well as the capacity to protect against formation of advanced glycation and lipoxidation end-products. For these reasons, the therapeutic potential of carnosine supplementation has been tested in numerous diseases in which ischemic or oxidative stress are involved. For several pathologies, such as diabetes and its complications, ocular disease, aging, and neurological disorders, promising preclinical and clinical results have been obtained. Also the pathophysiological relevance of serum carnosinase, the enzyme actively degrading carnosine into l-histidine and β-alanine, is discussed. The carnosine system has evolved as a pluripotent solution to a number of homeostatic challenges. l-Histidine, and more specifically its imidazole moiety, appears to be the prime bioactive component, whereas β-alanine is mainly regulating the synthesis of the dipeptide. This paper summarizes a century of scientific exploration on the (patho)physiological role of carnosine and related compounds. However, far more experiments in the fields of physiology and related disciplines (biology, pharmacology, genetics, molecular biology, etc.) are required to gain a full understanding of the function and applications of this intriguing molecule.
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Fonouni H, Esmaeilzadeh M, Jarahian P, Rad MT, Golriz M, Faridar A, Hafezi M, Jafarieh S, Kashfi A, Yazdi SHF, Soleimani M, Longerich T, Shevchenko M, Sakowitz O, Schmidt J, Mehrabi A. Early detection of metabolic changes using microdialysis during and after experimental kidney transplantation in a porcine model. Surg Innov 2012; 18:321-8. [PMID: 22308094 DOI: 10.1177/1553350610392063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Microdialysis (MD) can detect organ-related metabolic changes before they become measurable in plasma through the biochemical parameters. This study aims to evaluate the early detection of metabolic changes during experimental kidney transplantation (KTx). MATERIAL AND METHODS During preparation of 8 donor kidneys, one MD catheter was inserted in the renal cortex and samples were collected. After a 6-hour cold ischemia time (CIT), kidneys were implanted in the 8 recipient pigs. Throughout the warm ischemia time (WIT) and after reperfusion, kidneys were monitored. The interstitial glucose, lactate, pyruvate, glutamate, and glycerol concentrations were evaluated. RESULTS A significant decline in glucose level was observed at the end of CIT. The lactate level was reduced to the minimum point of 0.35 ± 0.08 mmol/L in CIT. After reperfusion, lactate values raised significantly. During the WIT, the pyruvate level increased, continued until the end of the WIT. For glutamate, a steady increase was noted during explantation, CIT, WIT, and early reperfusion phases. The increase of glycerol value continued in the early postreperfusion, which was then followed by a sharp decline. CONCLUSION MD is a fast and simple minimally invasive method for measurement of metabolic substrates in renal parenchyma during KTx. MD offers the option of detecting minor changes of interstitial glucose, lactate, pyruvate, glutamate, and glycerol in every stage of KTx. Through the use of MD, metabolic changes can be continuously monitored during the entire procedure of KTx.
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Affiliation(s)
- Hamidreza Fonouni
- Department of General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany
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Lira EC, Gonçalves DA, Parreiras-E-Silva LT, Zanon NM, Kettelhut IC, Navegantes LC. Phosphodiesterase-4 inhibition reduces proteolysis and atrogenes expression in rat skeletal muscles. Muscle Nerve 2011; 44:371-81. [DOI: 10.1002/mus.22066] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Derave W, Everaert I, Beeckman S, Baguet A. Muscle carnosine metabolism and beta-alanine supplementation in relation to exercise and training. Sports Med 2010; 40:247-63. [PMID: 20199122 DOI: 10.2165/11530310-000000000-00000] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Carnosine is a dipeptide with a high concentration in mammalian skeletal muscle. It is synthesized by carnosine synthase from the amino acids L-histidine and beta-alanine, of which the latter is the rate-limiting precursor, and degraded by carnosinase. Recent studies have shown that the chronic oral ingestion of beta-alanine can substantially elevate (up to 80%) the carnosine content of human skeletal muscle. Interestingly, muscle carnosine loading leads to improved performance in high-intensity exercise in both untrained and trained individuals. Although carnosine is not involved in the classic adenosine triphosphate-generating metabolic pathways, this suggests an important role of the dipeptide in the homeostasis of contracting muscle cells, especially during high rates of anaerobic energy delivery. Carnosine may attenuate acidosis by acting as a pH buffer, but improved contractile performance may also be obtained by improved excitation-contraction coupling and defence against reactive oxygen species. High carnosine concentrations are found in individuals with a high proportion of fast-twitch fibres, because these fibres are enriched with the dipeptide. Muscle carnosine content is lower in women, declines with age and is probably lower in vegetarians, whose diets are deprived of beta-alanine. Sprint-trained athletes display markedly high muscular carnosine, but the acute effect of several weeks of training on muscle carnosine is limited. High carnosine levels in elite sprinters are therefore either an important genetically determined talent selection criterion or a result of slow adaptation to years of training. beta-Alanine is rapidly developing as a popular ergogenic nutritional supplement for athletes worldwide, and the currently available scientific literature suggests that its use is evidence based. However, many aspects of the supplement, such as the potential side effects and the mechanism of action, require additional and thorough investigation by the sports science community.
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Affiliation(s)
- Wim Derave
- Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
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Tesch PA, von Walden F, Gustafsson T, Linnehan RM, Trappe TA. Skeletal muscle proteolysis in response to short-term unloading in humans. J Appl Physiol (1985) 2008; 105:902-6. [PMID: 18535133 DOI: 10.1152/japplphysiol.90558.2008] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle atrophy is evident after muscle disuse, unloading, or spaceflight and results from decreased protein content as a consequence of decreased protein synthesis, increased protein breakdown or both. At this time, there are essentially no human data describing proteolysis in skeletal muscle undergoing atrophy on Earth or in space, primarily due to lack of valid and accurate methodology. This particular study aimed at assessing the effects of short-term unloading on the muscle contractile proteolysis rate. Eight men were subjected to 72-h unilateral lower limb suspension (ULLS) and intramuscular interstitial levels of the naturally occurring proteolytic tracer 3-methylhistidine (3MH) were measured by means of microdialysis before and on completion of this intervention. The 3MH concentration following 72-h ULLS (2.01 +/- 0.22 nmol/ml) was 44% higher (P < 0.05) than before ULLS (1.56 +/- 0.20 nmol/ml). The present experimental model and the employed method determining 3MH in microdialysates present a promising tool for monitoring skeletal muscle proteolysis or metabolism of specific muscles during conditions resulting in atrophy caused by, e.g., disuse and real or simulated microgravity. This study provides evidence that the atrophic processes are evoked rapidly and within 72 h of unloading and suggests that countermeasures should be employed in the early stages of space missions to offset or prevent muscle loss during the period when the rate of muscle atrophy is the highest.
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Affiliation(s)
- Per A Tesch
- Department of Physiology and Pharmacology, Mid Sweden Univ., SE- 831 25 Ostersund, Sweden.
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Iwata T, Gilispie A, Jorns C, Yamamoto S, Nowak G, Ericzon BG. Microdialysis monitoring for evaluation of the influence exerted by pneumoperitoneum on the kidney: an experimental study. Surg Endosc 2007; 22:938-42. [PMID: 17705079 DOI: 10.1007/s00464-007-9525-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 06/04/2007] [Accepted: 07/07/2007] [Indexed: 11/30/2022]
Abstract
BACKGROUND Laparoscopic donor nephrectomy has become the first choice for living donor kidney transplantation, offering advantages over open donor nephrectomy. This study aimed to evaluate kidney tissue metabolism during and after pneumoperitoneum using a microdialysis technique. METHODS Eight pigs underwent laparotomy and implantation of two microdialysis catheters: one in the cortex and one in the medulla of the left kidney. After laparotomy, the abdominal wall was closed, and pneumoperitoneum was induced with a constant standard pressure of 16 to 18 mmHg for 4 h, followed by rapid desufflation. In microdialysis samples collected from intrarenal catheters, markers of ischemia (glucose, lactate, pyruvate, and lactate-pyruvate ratio) and the marker of cell membrane injury (glycerol) were monitored. RESULTS There were no changes in glucose, lactate, or pyruvate level before, during, or after pneumoperitoneum, either in the cortex or in the medulla. Additionally, the calculated lactate-pyruvate ratio did not show signs of ischemia during or after pneumoperitoneum. However, with regard to the marker of cell injury, glycerol increased in the medulla after decompression from 22.57 +/- 3.76 to 35.67 +/- 5.43 mmol/l (p < 0.01). This release of glycerol in the medulla was significantly higher than in the cortex (area under the curve [AUC], 22.18 +/- 4.87 vs 34.79 +/- 7.88 mmol/l; p < 0.01). CONCLUSIONS The pattern of metabolic changes monitored in the kidney during and after pneumoperitoneum indicates some kind of cell injury predominant in the medulla without any signs of kidney ischemia. This nonischemic injury could be related to hyperperfusion of the kidney after decompression or injury to cells attributable to mechanical cell expansion at the point of rapid decompression.
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Affiliation(s)
- T Iwata
- Department for Clinical Science, Intervention and Technology (CLINTEC), Division of Transplantation Surgery, Karolinska Institute, Karolinska University Hospital, Huddinge, B56 141-86, Stockholm, Sweden.
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15
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Lira EC, Graca FA, Goncalves DAP, Zanon NM, Baviera AM, Strindberg L, Lönnroth P, Migliorini RH, Kettelhut IC, Navegantes LCC. Cyclic adenosine monophosphate-phosphodiesterase inhibitors reduce skeletal muscle protein catabolism in septic rats. Shock 2007; 27:687-94. [PMID: 17505310 DOI: 10.1097/shk.0b013e31802e43a6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have previously shown that catecholamines exert an inhibitory effect on muscle protein degradation through a pathway involving the cyclic adenosine monophosphate (cAMP) cascade in normal rats. In the present work, we investigated in vivo and in vitro effects of cAMP-phosphodiesterase inhibitors on protein metabolism in skeletal muscle from rats submitted to a model of acute sepsis. The in vivo muscle protein metabolism was evaluated indirectly by measurements of the tyrosine interstitial concentration using microdialysis. Muscle blood flow (MBF) was monitored by ethanol perfusion technique. Sepsis was induced by cecal ligation and puncture and resulted in lactate acidosis, hypotension, and reduction in MBF (-30%; P < 0.05). Three-hour septic rats showed an increase in muscle interstitial tyrosine concentration (approximately 150%), in arterial plasma tyrosine levels (approximately 50%), and in interstitial-arterial tyrosine concentration difference (approximately 200%; P < 0.05). Pentoxifylline (50 mg/kg of body weight, i.v.) infusion during 1 h after cecal ligation and puncture prevented the tumor necrosis factor alpha increase and significantly reduced by 50% (P < 0.05) the interstitial-arterial tyrosine difference concentration. In situ perfusion with isobutylmethylxanthine (IBMX; 10(-3) M) reduced by 40% (P < 0.05) the muscle interstitial tyrosine in both sham-operated and septic rats. Neither pentoxifylline nor IBMX altered MBF. The addition of IBMX (10(-3) M) to the incubation medium increased (P < 0.05) muscle cAMP levels and reduced proteolysis in both groups. The in vitro addition of H89, a protein kinase A inhibitor, completely blocked the antiproteolytic effect of IBMX. The data show that activation of cAMP-dependent pathways and protein kinase A reduces muscle protein catabolism during basal and septic state.
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16
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Wagner TK, Mulks MH. A subset of Actinobacillus pleuropneumoniae in vivo induced promoters respond to branched-chain amino acid limitation. ACTA ACUST UNITED AC 2007; 48:192-204. [PMID: 16995880 DOI: 10.1111/j.1574-695x.2006.00147.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Actinobacillus pleuropneumoniae is the causative agent of a necrotizing hemorrhagic pleuropneumonia in swine. In this study, we investigate the possibility that the limitation of branched-chain amino acids is a stimulus that A. pleuropneumoniae will encounter during infection and will respond to by up-regulation of genes involved in branched-chain amino acid biosynthesis and virulence. Actinobacillus pleuropneumoniae genetic loci that are specifically induced during infection were screened in vitro for expression in response to limitation of branched-chain amino acids. Of 32 in vivo induced promoter clones screened in vitro, eight were induced on chemically defined medium without isoleucine, leucine and valine as compared to complete chemically defined medium. We identify the genomic context of each clone and discuss its relevance to branched-chain amino acid limitation and virulence. We conclude that limitation of branched-chain amino acids is a cue for expression of a subset in vivo induced genes, including not only genes involved in the biosynthesis of branched-chain amino acids, but also other genes that are induced during infection of the natural host. These results suggest that limitation of branched-chain amino acids may be one of an array of environmental cues responsible for the induction of virulence-associated genes in A. pleuropneumoniae.
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Affiliation(s)
- Trevor K Wagner
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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17
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Haus JM, Miller BF, Carroll CC, Weinheimer EM, Trappe TA. The effect of strenuous aerobic exercise on skeletal muscle myofibrillar proteolysis in humans. Scand J Med Sci Sports 2006; 17:260-6. [PMID: 16787442 DOI: 10.1111/j.1600-0838.2006.00566.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Relatively little is known about the dynamics of the skeletal muscle protein pool following aerobic exercise. Myofibrillar protein synthesis has recently been shown to be substantially elevated for 3 days after a strenuous 60 min bout of one-legged aerobic exercise, and this increase was surprisingly equal to or greater than what has been shown numerous times following resistance exercise over the same time course. Because net protein accretion is the sum of protein synthesis and degradation, we sought to directly measure skeletal muscle myofibrillar proteolysis in five healthy young males in response to an identical strenuous 60 min aerobic exercise bout and at the same time points (rest, 6, and 24 h post-exercise and 48 and 72 h post-exercise in a subset of subjects). We measured skeletal muscle myofibrillar proteolysis by monitoring the release of the natural tracer 3-methylhistidine (3MH) from the vastus lateralis muscle into the interstitial space via microdialysis. Skeletal muscle interstitial 3MH concentration was no different (P>0.05) from rest (5.16+/-0.38 nmol/mL) after 6 (5.37+/-0.55 nmol/mL), 24 (5.40+/-0.26 nmol/mL), 48 (5.50+/-0.74 nmol/mL), or 72 h (4.73+/-0.28 nmol/mL). These results suggest that proteolysis of the myofibrillar fraction of skeletal muscle is relatively refractory to an intense aerobic exercise stimulus for up to 3 days, despite the large increase in synthesis of this muscle fraction following the same exercise stimulus. The apparent net myofibrillar protein accretion in the hours and days after exercise may occur in order to offset the large elevation in mixed muscle proteolysis that has been shown during similar bouts of intense one-legged aerobic exercise.
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Affiliation(s)
- J M Haus
- Human Performance Laboratory, Ball State University, Muncie, Indiana 47306, USA
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18
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Børsheim E, Kobayashi H, Traber DL, Wolfe RR. Compartmental distribution of amino acids during hemodialysis-induced hypoaminoacidemia. Am J Physiol Endocrinol Metab 2006; 290:E643-52. [PMID: 16278248 DOI: 10.1152/ajpendo.00267.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intracellular concentrations of essential amino acids (EAA) in muscle are maintained relatively constant under a variety of conditions. However, the effect of a decrease in blood amino acid concentrations on intracellular concentrations is not clear. Similarly, the relation between intracellular and interstitial concentrations has not been determined in this circumstance. Thus the aim of this study was to determine the effect of hypoaminoacidemia on intracellular, interstitial, and plasma concentrations of EAA and the mechanisms responsible for the respective changes. Twelve normal pigs were investigated before and during 120 min of hemodialysis by use of stable-isotope tracer methodology, microdialysis technique, and muscle biopsies. During hemodialysis, there was a decrease in the interstitial fluid concentrations of phenylalanine, leucine, alanine, and lysine that corresponded to their decrease in plasma concentration. Nonetheless, the intracellular concentrations of these amino acids were maintained at the basal levels throughout the entire period due principally to a reduction in the rate of incorporation of amino acids into protein that was approximately equivalent to the decrease in uptake from the plasma. In conclusion, intracellular concentrations of amino acids are regulated to maintain relatively constant values, even when plasma and interstitial concentrations fall as a consequence of hemodialysis.
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Affiliation(s)
- Elisabet Børsheim
- Metabolism Unit, Department of Surgery, Shriners Hospitals for Children/Galveston, and University of Texas Medical Branch, Galveston, Texas 77550, USA.
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19
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Abstract
PURPOSE OF REVIEW This review discusses recent developments in the utilization of microdialysis to assess tissue amino acid kinetics. RECENT FINDINGS Three questions regarding the use of microdialysis to assess amino acid kinetics have recently been addressed. Does glutamate measured in the interstitial fluid of the brain represent neurotransmission activity? Can local nitric oxide production be determined with the use of microdialysis? Finally, how can skeletal muscle amino acid metabolism be studied in more detail utilizing microdialysis? SUMMARY The most appropriate way to assess tissue kinetics is by the use of tracers. The number of studies actually utilizing microdialysis in combination with tracers to assess amino acid kinetics is rather limited. However, these studies show exiting new insides into in-vivo amino acid kinetics.
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Affiliation(s)
- Olav Rooyackers
- Centre for Surgical Sciences, Karolinska Institutet at Karolinska University Hospital, Huddinge, Sweden.
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20
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Abstract
Microdialysis conceivably enables longitudinal and simultaneous investigation of several metabolites by repeated measurements in skeletal muscle. We used and evaluated microdialysis as an in vivo method to characterize the time-course and relative kinetics of pyruvate, glucose, lactate, glycerol, hypoxanthine, uric acid, and urea, in skeletal muscles, exposed to ischemia and reperfusion, in eight patients having arthroscopic-assisted anterior cruciate ligament reconstruction. A dialysis probe was implanted before surgery in the rectus femoris muscle. Dialysate samples were collected at 10-minute intervals at a flow rate of 1 microL/minute until 2 hours after tourniquet deflation. Ninety minutes of ischemia resulted in accumulation of lactate (234% +/- 38%), hypoxanthine (582% +/- 166%), and glycerol (146% +/- 46%), consumption of glucose (54% +/- 9%) and pyruvate (16% +/- 44%), and a slight decrease of urea (78% +/- 11%) compared with baseline (100%). Uric acid was unchanged (95% +/- 12%). Within 90 minutes after tourniquet deflation the concentrations were virtually normalized for all measured metabolites, suggesting that the duration of ischemia was well tolerated by the patients. The results indicate that the use of microdialysis for monitoring energy metabolic events during orthopaedic surgery that requires ischemia and reperfusion is feasible and safe.
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Affiliation(s)
- Bengt Ostman
- Department of Orthopaedics, Uppsala University, Sweden.
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21
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Nordsborg N, Mohr M, Pedersen LD, Nielsen JJ, Langberg H, Bangsbo J. Muscle interstitial potassium kinetics during intense exhaustive exercise: effect of previous arm exercise. Am J Physiol Regul Integr Comp Physiol 2003; 285:R143-8. [PMID: 12663256 DOI: 10.1152/ajpregu.00029.2003] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interstitial K+ ([K+]i) was measured in human skeletal muscle by microdialysis during exhaustive leg exercise, with (AL) and without (L) previous intense arm exercise. In addition, the reproducibility of the [K+]i determinations was examined. Possible microdialysis-induced rupture of the sarcolemma was assessed by measurement of carnosine in the dialysate, because carnosine is only expected to be found intracellularly. Changes in [K+]i could be reproduced, when exhaustive leg exercise was performed on two different days, with a between-day difference of approximately 0.5 mM at rest and 1.5 mM at exhaustion. The time to exhaustion was shorter in AL than in L (2.7 +/- 0.3 vs. 4.0 +/- 0.3 min; P < 0.05). Furthermore, [K+]i was higher from 0 to 1.5 min of the intense leg exercise period in AL compared with L (9.2 +/- 0.7 vs. 6.4 +/- 0.9 mM; P < 0.001) and at exhaustion (11.9 +/- 0.5 vs. 10.3 +/- 0.6 mM; P < 0.05). The dialysate content of carnosine was elevated by exercise, but low-intensity exercise resulted in higher dialysate carnosine concentrations than subsequent intense exercise. Furthermore, no relationship was found between carnosine concentrations and [K+]i. Thus the present data suggest that microdialysis can be used to determine muscle [K+]i kinetics during intense exercise, when low-intensity exercise is performed before the intense exercise. The high [K+]i levels reached at exhaustion can be expected to cause fatigue, which is supported by the finding that a faster accumulation of interstitial K+, induced by prior arm exercise, was associated with a reduced time to fatigue.
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Affiliation(s)
- Nikolai Nordsborg
- The August Krogh Institute, IFI, Universitetsparken 13, DK-2100 Copenhagen Ø, Denmark
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22
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Nowak G, Ungerstedt J, Wernerman J, Ungerstedt U, Ericzon BG. Clinical experience in continuous graft monitoring with microdialysis early after liver transplantation. Br J Surg 2002; 89:1169-75. [PMID: 12190684 DOI: 10.1046/j.1365-2168.2002.02187.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Early detection of impaired graft function after transplantation is essential. Microdialysis permits continuous monitoring of metabolic changes by mimicking the passive function of a capillary blood vessel by perfusion of a tubular semipermeable membrane introduced into the tissue. Based on the results of animal experiments, a clinical pilot study was undertaken. METHODS Ten consecutive patients undergoing whole-organ orthotopic liver transplantation were studied. Intrahepatic implantation of a microdialysis catheter was performed at the end of the operation. A reference catheter was placed in the subcutaneous tissue over the right pectoral area immediately after abdominal closure. Consecutive serial samples were collected at 1-h intervals for 3 days after the operation. Glucose, lactate, pyruvate and glycerol concentrations were measured. RESULTS During the first 24 h, the glucose level was higher in the liver than in reference tissue. Initially, increased mean(s.e.m.) levels of lactate (7.0(1.9) mmol/l) were observed in the liver, with a rapid decrease (to 2.7(0.3) mmol/l) over 24 h. A decrease in, and later stabilization of, the lactate : pyruvate ratio in the liver, from 18.7(4.2) to 10.0(1.1), was observed within 24 h after transplantation. Liver glycerol levels decreased from 62.3(7.4) to 24.3(7.5) micro mol/l within the first 16 h after reperfusion and remained stable thereafter. CONCLUSION Microdialysis allows continuous monitoring of tissue metabolism in the transplanted liver. The procedure is easy to perform and safe. The specific detection and monitoring of pathological changes in the liver graft (e.g. arterial and portal vein thrombosis, or early rejection) with microdialysis should be addressed in further studies.
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Affiliation(s)
- G Nowak
- Department of Transplantation Surgery, Karolinska Institute, Huddinge University Hospital, Huddinge, Sweden.
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23
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Nowak G, Ungerstedt J, Wernerman J, Ungerstedt U, Ericzon BG. Metabolic changes in the liver graft monitored continuously with microdialysis during liver transplantation in a pig model. Liver Transpl 2002; 8:424-32. [PMID: 12004341 DOI: 10.1053/jlts.2002.32943] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Microdialysis provides the opportunity to continuously monitor metabolic changes in tissue. The aim of the study is to monitor metabolic changes in the liver graft over time during transplantation in a pig model. Fourteen littermate female pigs with a body weight of 30 to 34 kg were used for seven orthotopic liver transplantations. Intrahepatic implantation of a microdialysis catheter into the liver graft was performed in the donor. Microdialysis samples were collected at 20-minute intervals during the donor operation, cold preservation, and for 7 hours after reperfusion in the recipient. Glucose, lactate, pyruvate, and glycerol concentrations were measured. After cold perfusion, glucose, lactate, and glycerol levels increased, whereas pyruvate levels decreased rapidly. During cold storage, glucose and glycerol levels increased, whereas lactate levels remained stable and pyruvate levels were undetectable. During implantation of the liver graft, glucose, lactate, and glycerol levels showed an accelerated increase. After portal reperfusion, glucose, lactate, and glycerol levels continued to increase for another 40 to 60 minutes, after which they decreased and finally settled at normal levels. At this time, pyruvate levels increased, with a peak within 2 hours after reperfusion, and then decreased to normal levels. Calculated lactate-pyruvate ratio increased after cold perfusion and remained stable during cold storage. During rewarming, it showed an accelerated increase, but after reperfusion, it decreased rapidly. Rewarming and reperfusion are most harmful to the liver, reflected by an accelerated increase in glucose and glycerol levels and lactate-pyruvate ratio. High intrahepatic glucose levels during ischemia appear to be a liver-specific event, which may represent glycogen degradation in injured hepatocytes.
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Affiliation(s)
- Grzegorz Nowak
- Department of Transplantation Surgery, Karolinska Institute, Huddinge University Hospital, Sweden.
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24
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Binnert C, Tappy L. Microdialysis in the intensive care unit: a novel tool for clinical investigation or monitoring? Curr Opin Clin Nutr Metab Care 2002; 5:185-8. [PMID: 11844986 DOI: 10.1097/00075197-200203000-00011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Microdialysis is a minimally invasive tool that allows us to gain insight into metabolism at the tissue level. In human investigations, it can be safely performed in the brain (neurosurgical patients), skeletal muscle and adipose tissue. Basically, the technique allows interstitial concentrations of small solutes to be evaluated. Several limitations of the method and possible ways to circumvent them are indicated. Recent technical developments are reviewed. At present, this method is rarely used in metabolic monitoring of critically ill patients, but its potential applications are highlighted.
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25
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Baslow MH, Suckow RF, Berg MJ, Marks N, Saito M, Bhakoo KK. Differential expression of carnosine, homocarnosine and N-acetyl-L-histidine hydrolytic activities in cultured rat macroglial cells. J Mol Neurosci 2001; 17:351-9. [PMID: 11859931 DOI: 10.1385/jmn:17:3:351] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
N-acetyl-L-histidine (NAH) and N-acetyl-L-aspartate (NAA) are representatives of two series of substances that are synthesized by neurons and other cells in the vertebrate central nervous system (CNS). Histidine containing homologs of NAH are beta-alanyl-L-histidine or carnosine (Carn) and gamma-aminobutyrl-L-histidine or homocarnosine (Hcarn). A homolog of NAA is N-acetylaspartylglutamate (NAAG). These substances belong to a unique group of osmolytes in that they are synthesized in cells that may not to be able to hydrolyze them, and are released in a regulated fashion to a second compartment where they can be rapidly hydrolyzed. In this investigation, the catabolic activities for NAH, Carn, and Hcarn in cultured macroglial cells and neurons have been measured, and the second compartment for NAH and Hcarn has been identified only with astrocytes. In addition, oligodendrocytes can only hydrolyze Carn, although Carn can also be hydrolyzed by astrocytes. Thus, astrocytes express hydrolytic activity against all three substrates, but oligodendrocytes can only act on Carn. The cellular separation of these hydrolytic enzyme activities, and the possible nature of the enzymes involved are discussed.
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Affiliation(s)
- M H Baslow
- Nathan S. Kline Institute for Psychiatric Research, Center for Neurochemistry, Orangeburg, NY 10962, USA.
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26
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Damian MS, Sauter W, Reichmann H. Subcutaneous microdialysis in mitochondrial cytopathy. Muscle Nerve 2001; 24:648-53. [PMID: 11317274 DOI: 10.1002/mus.1050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We present the results of subcutaneous microdialysis, a new minimally invasive biochemical monitoring technique, in mitochondrial cytopathy. We studied 6 ambulatory patients with mitochondrial cytopathy and 6 controls without mitochondrial disease using a subcutaneous probe for continuous microdialysis, and obtained measurements of lactate, pyruvate, and glucose from samples gathered at 30-60 min intervals during the day and at 3-h intervals at night. The lactate:pyruvate ratio (LPR) was calculated and related to disease severity and metabolic stress. Microdialysis was well tolerated. Controls had stable lactate and pyruvate values in the normal range and a low LPR (average values between 0.0114 and 0.0145). Patients had widely fluctuating lactate and pyruvate values, a higher average LPR between 0.0187 and 0.0724, and marked diurnal variation, especially in the severely affected patients. Increases in the LPR coincided with metabolic stress in individual cases. We conclude that subcutaneous microdialysis is well tolerated and enables continuous metabolic monitoring of patients with mitochondrial cytopathy. It has particular potential for use in the identification of metabolic risk factors and may help to assess the impact of therapeutic regimens.
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Affiliation(s)
- M S Damian
- Department of Neurology, Technical University of Dresden, Fetscherstrasse 74, Dresden 01307, Germany.
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