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Effects of inactivity on human muscle glutathione synthesis by a double-tracer and single-biopsy approach
Francesco Agostini, Luciano Dalla Libera, Joern Rittweger, Sara Mazzucco, Mihaela Jurdana, Igor B. Mekjavić, Rado Pišot, Luisa Gorza, Marco Narici, Gianni Biolo, 2010, original scientific article

Abstract: Oxidative stress is often associated to inactivity-mediated skeletal muscle atrophy. Glutathione is one of the major antioxidant system stimulated, both at muscular and systemic level, by activation of oxidative processes. We measured changes in glutathione availability, oxidative stress induction and atrophy extent mediated by 35-days of experimental bed rest in vastus lateralis muscle of healthy human volunteers. To assess muscle glutathione synthesis, we applied a novel single-biopsy and double-tracer ([2H2]glycine and [15N]glycine) approach based on evaluation of steady-state precursor incorporation in product. The correlations between the traditional (multiple-samples, one-tracer) and new (one-sample, double-tracer infusion) methods were analyzed in erythrocytes by Passing & Bablok and Altman-Bland tests. Muscle glutathione absolute synthesis rate increased following bed rest from 5.5 1.1 to 11.0 1.5 mmol (kg wet tissue / day)-1 (n=9; p=0.02) while glutathione concentration failed to change significantly. Bed rest induced vastus lateralis muscle atrophy, as assessed by pennation angle changes measured by ultrasonography (from 18.6 1.0 to 15.3 0.9 degrees; p=0.01) and thickness changes (from 2.3 0.2 to 1.9 0.1 cm; p<0.001). Moreover, bed rest increased protein oxidative stress, as measured by muscle protein carbonylation changes (from 0.6 0.1 to 1.00 0.1 Oxy RP-1; p<0.04). In conclusion, we developed in erythrocytes a new minimally-invasive method to determine peptide synthesis rate in human tissues. Application of the new method to skeletal muscle suggests that disuse atrophy is associated to oxidative stress induction as well as to compensatory activation of the glutathione system
Found in: osebi
Keywords: Antioxidant system, Muscle damage, Oxidative stress, bed rest, muscle glutathione, stable isotopes
Published: 15.10.2013; Views: 2266; Downloads: 88
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Hyperhomocysteinemia: relation to cardiovascular disease and venous thromboembolism
Nadja Plazar, Mihaela Jurdana, 2012, independent scientific component part or a chapter in a monograph

Found in: osebi
Keywords: hiperhomocisteinemija, krvna obolenja, venski tromboembolizem, kardiovaskularne bolezni
Published: 15.10.2013; Views: 2015; Downloads: 62
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Cancer cachexia-anorexia syndrome and skeletal muscle wasting
Mihaela Jurdana, 2009, review article

Abstract: Cachexia-anorexia syndrome is a common and important indicator of cancer. It occurs in 30% to 80% of cancer patients. Cachexia means "bad condition" and may be present in the early stages of tumor growth, before any signs of malignancy. Cancer cachexia is a syndrome of progressive body wasting, characterized by loss of adipose tissue and skeletal muscle mass. In most cancer patients, cachexia is characteriyed by anorexia, which implies a failure of food intake, regulated through a complex system of hormones and neuropeptides. A decline in food intake relative to energy expenditure is a fundamental physiologic derangement leading to cancer associated weight loss. The weight loss in patients with cachexia-anorexia syndrome differs from that in caloric starvation or anorexia nervosa. The pathophysiology of cancer cachexia is not fully understood; however, studies have shown that cytokines are important in the alteration of the carbohydrate, lipid and protein metabolism. Cancer, prolonged bed rest, HIV infection and aging are conditionsin which muscle wasting is a common feature. An intervention that may potentially attenuate the progression of muscle wasting in cancer patientsis resistance exercise training, defined as multiple repetitions of static or dynamic muscular contractions that increase muscle mass. The main components of the pathological state of cachexia are anorexia and metabolic abnormalities such as fat depletion and muscle protein catabolism. Future developments may concentrate on the molecular abnormalities of cachexia and on examination of the functional benefit of resistance exercise training for cancer related muscle wasting.
Found in: osebi
Keywords: cancer cachexia, muscle wasting, cytokines, muscle
Published: 15.10.2013; Views: 2204; Downloads: 62
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Neural agrin changes the electrical properties of developing human skeletal muscle cells
Mihaela Jurdana, Guido Fumagalli, Zoran Grubič, Paola Lorenzon, Tomaž Marš, Marina Sciancalepore, 2009, original scientific article

Abstract: Recent investigations suggest that the effects of neural agrin might not be limited to neuromuscular junction formation and maintenance and that other aspects of muscle development might be promoted by agrin. Here we tested the hypothesis that agrin induces a change in the excitability properties in primary cultures of non-innervated human myotubes. Electrical membrane properties of human myotubes were recorded using the whole-cell patch-clamp technique. Cell incubation with recombinant chick neural agrin (1 nM) led to amore negative membrane resting potential. Addition of strophanthidin, a blocker of the Na(+)žK(+) ATPase, depolarized agrin-treated myotubes stronger than control, indicating, in the presence of agrin, a higher contribution of the Na(+)žK(+) ATPase in establishing the resting membrane potential. Indeed, larger amounts of both the alpha1 and the alpha2 isoforms of the Na(+)žK(+) ATPase protein were expressed in agrin-treated cells. A slight but significantdown-regulation of functional apamin-sensitive K(+) channels was observed after agrin treatment. These results indicate that neural agrin mightact as a trophic factor promoting the maturation of membrane electrical properties during differentiation, confirming the role of agrin as a general promoter of muscle development.
Found in: osebi
Keywords: agrin, myogenesis, electrical membrane properties, skeletal muscle, Na+/K+ pump
Published: 15.10.2013; Views: 1791; Downloads: 85
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Hyperhomocysteinemia and the role of B vitamins in cancer
Nadja Plazar, Mihaela Jurdana, 2010, review article

Found in: osebi
Keywords: onkologija, biokemija, B vitamini, rak
Published: 15.10.2013; Views: 2172; Downloads: 60
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Whole muscle contractile parameters and thickness loss during 35-day bed rest
Rado Pišot, Marco Narici, Boštjan Šimunič, Maarten D. de Boer, Olivier Seynnes, Mihaela Jurdana, Gianni Biolo, Igor B. Mekjavić, 2008, original scientific article

Abstract: Extended exposure to microgravity leads to significant musculoskeletal adaptations. Contractile parameters of four skeletal muscles (biceps brachii-BB, vastus medialis-VM, biceps femoris-BF and gastrocnemius medialis-GM) were measured in ten healthy males (aged 22.3 +/- 2.2 years) during 35 days of horizontal bed rest by a mechanomyography-based method termed 'tensiomyography' (TMG). Two contractile parameters: contraction time (Tc) and maximal displacement (Dm) were individually measured from electrically evoked maximal single twitch TMG response of all four muscles before and after bed rest. Significant changes in Tc were found after bed rest, as shown by an increase in GM muscle Tc by 18% (p < 0.01). Dm values significantly increased (p < 0.01) after bed rest, by 24, 26 and 30% in the VM, BF and GM muscles, respectively. In the GM, the change in Dm significantly correlated with the decrease in muscle thickness (r = -0.70, p < 0.01). In conclusion, bed rest induced changes in both Dm and Tc of the TMG signal; changes in Dm being inversely related to those of muscle thickness. Amongst the investigated muscles, most affected, in terms of atrophy and mechanical alterations, were those of the lower limbs. The observed increase in Dm may be attributed to a decrease in muscle, as well as tendon stiffness, causing larger muscle fibre and non-contractile tissue oscillations following contraction.
Found in: osebi
Keywords: Bed rest, skeletal muscle, muscle contraction, muscle thickness, mechanomyography, tensiomiography, ultrasound
Published: 15.10.2013; Views: 2418; Downloads: 79
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Odziv sestave telesa, mišične togosti in ravnotežja po 35-dnevni odsotnosti gibanja pri mladih in zdravih preiskovancih
Boštjan Šimunič, Joern Rittweger, Gregor Cankar, Mihaela Jurdana, Tadeja Volmut, Tina Šetina, Igor B. Mekjavić, Rado Pišot, 2008, original scientific article

Abstract: Uvod: Problemi sedečega načina sodobnega življenja se kažejo v fizioloških odzivih, tako pri starejših kot tudi pri mlajših ljudeh. Cilj raziskave je bilugotoviti odziv morfoloških in skeletno-mišičnih značilnosti ter izgubo funkcionalnih sposobnosti ohranjanja ravnotežja po 35-dnevni popolni gibalni nedejavnosti in zagotovljeni uravnoteženi prehrani glede na njeno sestavo in preiskovančevo telesno težo. Metode: Deset moških preiskovancev (starih 24,32,6 let) je v bolnišničnem okolju preležalo 35 dni v vodoravnem položaju. Fiziološke odzive telesa smo vrednotili z merjenji telesne, maščobne in mišične mase, mineralne vsebnosti sprednje golenske kosti, togosti trebuha dveh funkcionalno različnih glav antigravitacijske mišice in sposobnost ohranjanja ravnotežja. Rezultati: Preiskovanci so v povprečju značilno izgubili 0,97 % (P=0,001) telesne teže, 4,1 % (P=0,009) mišične mase in 1,7 % (P=0,000) mineralne gostote tibialne kosti ter pridobili 1,4 % (P<0,000) maščobne mase. Mišična togost se je značilno zmanjšala od 8. dne ležanja (P=0,006) dalje pri distalni in že od 1. dneva (P=0,007) dalje pri proksimalniglavi notranje stegenske mišice ter se 14. dan po zaključku BR vrnila v izhodiščno stanje le pri distalni glavi. Po zaključku BR in dan kasneje smo ugotovili značilno izgubo ohranjanja ravnotežja za 9,5 % (P=0,006), in 17,4 % (P=0,000), medtem ko 14. dan po zaključku ležanja ni biloveč značilnih razlik. Zaključek: Povzamemo lahko, da z uravnoteženo prehrano lahko omejimo izgubo telesne teže in pridobivanje maščobne mase, vendar ne moremo zmanjšati izgube mišične mase ter mineralne vsebnosti tibialne kosti. Ugotovili smo, da se mišična togost zmanjšuje v dveh časovno zakasnjenih procesih. Sposobnost ohranjanja ravnotežja je zmanjšana v vsaj prvih 24 urah po zaključku ležanja.
Found in: osebi
Keywords: popolna gibalna neaktivnost, okoljska fiziologija, tenziomiografija, ravnotežje, morfologija, kostna mineralna vsebnost, mišična togost
Published: 15.10.2013; Views: 2415; Downloads: 39
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Vpliv 35 dnevnega mirovanja na koncentracijo homocisteina v krvi
Mihaela Jurdana, Nadja Plazar, Rado Pišot, 2008, original scientific article

Found in: osebi
Keywords: simulirana breztežnost, telesna neaktivnost, homocistein, folna kislina
Published: 10.07.2015; Views: 1655; Downloads: 5
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Radiation effects on skeletal muscle
Mihaela Jurdana, 2008, review article

Found in: osebi
Keywords: radiation effects, neuromuscular junction, muscle satellite cells, aging
Published: 10.07.2015; Views: 1826; Downloads: 103
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Vloga prehrane pri preprečevanju in zdravljenju nealkoholne zamaščenosti jeter
Tamara Poklar Vatovec, Mihaela Jurdana, Mateja Martinc, 2015, published scientific conference contribution

Found in: osebi
Keywords: nealkoholna zamaščenost jeter, prehranjevanje, življenjski slog, zdravljenje
Published: 14.10.2015; Views: 2430; Downloads: 53
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