The aging process is associated with a decline in mitochondrial functions. Mitochondria dysfunction is involved in initiation and progression of many health problems including neuromuscular, metabolic and cardiovascular diseases. It is well known that endurance exercise improves mitochondrial function, especially in the elderly. However, recent studies have demonstrated that resistan ce training lead also to substantial increases in mitochondrial function in skeletal muscle. A comprehensive understanding of the cellular mechanisms involved in the skeletal muscle mitochondrial adaptations to exercise training in healthy elderly subjects, can help practitioners to design and prescribe more effective exercise trainings., M. M. Ziaaldini, S. R. A. Hosseini, M. Fathi., and Obsahuje bibliografii
Mitochondria are involved in cellular functions that transcend the traditional role of these organelles as the energy factory of the cell. Their relative inaccessibility and the difficulties involved in attempts to study them in their natural environment - the cytosol - has delayed much of this understanding and they still have many secrets to yield. One of the relatively new fields in this respect is undoubtedly the analysis of mitochondrial membrane potential. The realization that its alteration may have important pathophysiological consequences has led to an increased interest in measuring this variable in a variety of biological settings, including cardiovascular diseases. Measurements of mitochondrial membrane potential tell us much about the role of mitochondria in normal cell function and in processes leading to cell death. However, we must be aware of the limitations of using isolated mitochondria, single cells and different fluorescent indicators., L. Škárka, B. Ošťádal., and Obsahuje bibliografii
Homeostasis of reactive oxygen species (ROS) in cardiomyocytes is critical for elucidation of normal heart physiology and pathology. Mitochondrial phospholipases A2 (mt-PLA2) have been previously suggested to be activated by ROS. Therefore, we have attempted to elucidate physiological role of such activation. We have found that function of a specific i-isoform of mitochondrial phospholipase A2 (mt-iPLA2) is activated by tert-butylhydroperoxide in isolated rat heart mitochondria. Isoform specificity was judged from the inhibition by bromoenol lactone (BEL), a specific iPLA2 inhibitor. Concomitant uncoupling has been caused by free fatty acids, since it was inhibited by bovine serum albumin. The uncoupling was manifested as a respiration burst accompanied by a slight decrease in mitochondrial inner membrane potential. Since this uncoupling was sensitive to carboxyatractyloside and purine nucleotide di- and triphosphates, we conclude that it originated from the onset of fatty acid cycling mediated by the adenine nucleotide translocase (major contribution) and mitochondrial uncoupling protein(s) (minor contribution), respectively. Such a mild uncoupling may provide a feedback downregulation of oxidative stress, since it can further attenuate mitochondrial production of ROS. In conclusion, ROS-induced function of cardiac mt-iPLA2 may stand on a pro-survival side of ischemia-reperfusion injury., Ježek, J. ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Cíl: Hlavním cílem studie je popsat transverzální a longitudinální mobilitu nervus medianus u pacientů se syndromem karpálního tunelu před otevřenou dekompresí karpálního tunelu a s odstupem po ní. Materiál a metodika: V období od března 2007 do června 2009 bylo do studie zahrnuto celkem 72 pacientů se syndromem karpálního tunelu. Vyšetření pohybu nervu bylo provedeno neinvazivně pomocí ultrazvuku před operací a několik měsíců po operaci. Transverzální pohyb byl měřen v úrovni os pisiforme a podélný pohyb byl měřen na volární straně předloktí ve vzdálenosti 8–11 cm proximálně od zápěstí. Dekomprese karpálního tunelu byla provedena standardní otevřenou technikou. Výsledky: Průměrná transverzální amplituda nervu byla v našem vzorku 1,82 mm předoperačně a 1,76 mm pooperačně a rozdíly nebyly statisticky významné (p > 0,05). Průměrná amplituda longitudinálního pohybu nervus medianus byla 3,74 mm předoperačně a 3,89 mm pooperačně a rozdíl nebylo možno hodnotit jako statisticky významný (p > 0,05). Závěr: Po otevřené dekompresi karpálního tunelu nedochází ke statisticky významným změnám v transverzální a ani v longitudinální mobilitě nervus medianus. Otevřená dekomprese u pacientů se syndromem karpálního tunelu nemá vliv na schopnost nervus medianus přizpůsobovat se pohybu okolních struktur., Aim: The main objective of the study was to describe transverse and longitudinal movement of the median nerve in patients with the carpal tunnel syndrome before and with delay after open decompression of the carpal tunnel. Materials and Methods: From March 2007 to July 2009, the study enrolled a total of 72 patients with the carpal tunnel syndrome. The examination of nerve movement was performed noninvasively by ultrasound before and several months after the surgery. Transverse nerve amplitude was measured at the level of the pisiform bone. Longitudinal movement was measured on the forearm at a distance of 8–11 cm proximal to the wrist. The standard open surgery was performed. Results: The mean of maximum transverse amplitude of the median nerve in our sample was 1.82 mm preoperatively and 1.76 mm postoperatively, and the difference was not statistically significant (p > 0.05). The average amplitude of the longitudinal movement of the median nerve was 3.74 mm preoperatively and 3.89 mm postoperatively, and the difference was not considered statistically significant (p > 0.05). Conclusions: There were no statistically significant changes in transverse or longitudinal movement of the median nerve after open carpal tunnel decompression. Open decompression does not affect biomechanical parameters of the median nerve in carpal tunnel syndrome patients. Key words: carpal tunnel syndrome – median nerve – ultrasound – mobility – nerve movement – biomechanics The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE “uniform requirements” for biomedical papers., and A. Fibír, R. Čáp, L. Ungermann, J. Vaněk
We investigated how selected electromorphological parameters of myelinated axons influence the preservation of interspike intervals when the propagation of action potentials is corrupted by axonal intrinsic noise. Hereby we tried to determine how the intrinsic axonal noise influences the performance of axons serving as carriers for temporal coding. The strategy of this coding supposes that interspike intervals presented to higher order neurons would minimally be deprived of information included in interspike intervals at the axonal initial segment. Our experiments were conducted using a computer model of the myelinated axon constructed in a software environment GENESIS (GEneral NEural SImulation System). We varied the axonal diameter, myelin sheath thickness, axonal length, stimulation current and channel distribution to determine how these parameters influence the role of noise in spike propagation and hence in preserving the interspike intervals. Our results, expressed as the standard deviation of spike travel times, showed that by stimulating the axons with regular rectangular pulses the interspike intervals were preserved with a microsecond accuracy. Stimulating the axons with pulses imitating postsynaptic currents, greater changes of interspike intervals were found, but the influence of implemented noise on the jitter of interspike intervals was approximately the same., E. Kuriščák, S. Trojan, Z. Wünsch., and Obsahuje bibliografii
The pattern-reversal (P-VEPs) and the motion-onset (M-VEPs) of visual evoked potentials were modeled by means of three damped oscillators (O1, O2, O3) of identical construction. The O1, assumed to simulate the response of primary visual area (V1), was driven by the firing density of the lateral geniculate nuclei. O1 contributed mainly to the N75 and P100 peaks of the P-VEPs. The O2, driven by the O1 output, mimics the activity of V2, V3a, and MT. It contributed to the negative peak N145 of the P-VEPs or to the N160 in the M-VEPs. The O3 was suggested to model late slow processes probably of an attentive origin. The model parameters were set by optimization to follow the P-VEPs and M-VEPs obtained as a grand average of four young volunteers (PZ - A2 lead). The evoked potentials were described with normalized root mean square error lower than 13 %., J. Kremláček, M. Kuba, J. Holčík., and Obsahuje bibliografii
V roce 2004 došlo v České republice k zásadním legislativním změnám v oblasti postgraduálního vzdělávání lékařů (zákon č. 95/2004 Sb.). Nahrazení dvojstupňového systému specializačního vzdělávání jednostupňovým s sebou přineslo problémy a podle našeho názoru nevedlo k jednoznačnému zkvalitnění postgraduálního vzdělávání, spíše naopak. K vytvoření vlastního lokálního systému postgraduálního vzdělávání na našem pracovišti nás vedla snaha podpořit kvalitu předatestační přípravy budoucích specialistů v interních oborech s uplatněním 4 základních principů: principu robustního interního základu jako platformy pro získání další specializace, principu opakování pro fixaci znalostí, principu kontroly znalostí a v neposlední řadě principu aktivní účasti v systému vzdělávání., In 2004 the principal legislative changes were accepted in the field of postgraduate medical education in Czech Republic (law No. 95/2004 Code). Replacement of two-stage system of specialized education by its one- stage option has brought some problems and according to our opinion did not lead to clear improvement of postgraduate education, more likely the other way around. Our effort to improve the quality of process of postgraduate specialization in internal medicine brought us to creation of own local system of postgraduate education using the next 4 basic principles: principle of robust internal base as a platform for the following specialization, principle of repeating to fix the knowledge, principle of knowledge control and last but not least principle of active participation in educational system., and Renata Kratochvílová, Milan Kvapil
The growth in the field of construction of shallow underground structures has been associated with construction of new roads, collectors and other structures. This contribution deals with modeling of distribution pattern of the maximum velocity amplitude (blasting vibration field) on surface basement. This basement will be situated within small distance from source of technical seismicity that is used as a part of technological processes. The model represents seismic effect of blasting operati on in shallow tunnel. Plaxis 2D modeling system and its dynamic module based on finite element method are used for this presentation., Martin Stolárik., and Obsahuje bibliografické odkazy
The study presents a modification to conventional finite element method under plane strain conditions to address the problem of successive excavation of linear parts of tunnels. Although the successive excavation is a three-dimensional mechanical problem, the designers often prefer 2D analysis owing to considerably simple and transparent geometric model and fast computations when compared to a 3D solution. The main idea behind the suggested method referred to as, 2D3D model, is to express the influence of excavation of a single stroke of soil not only in the particular cross section but in the entire soil body in front of and behind the examined profile. This is achieved by introducing special finite elements which have common triangular cross-section but are of infinite length in the longitudinal direction. The longitudinal approximations of the displacement field adopt the evolution of convergence measurements, while standard linear shape functions are kept in the element triangular cross-section. A profile corresponding to the city road tunnel Blanka in Prague with available convergence measurements was examined to verify the method. The results show that the method provides reasonably accurate results when compared to the convergence confinement method without the need to subjectively determine the lambda parameter. It also significantly reduces the computational time of a more versatile but complex 3D analysis., Tomáš Janda, Michal Šejnoha and Jiří Šejnoha., and Obsahuje bibliografii
Understanding mitochondrial role in normal physiology and pathological conditions has proven to be of high importance as mitochondrial dysfunction is connected with a number of disorders as well as some of the most common diseases (e.g. diabetes or Parkinson’s disease). Modeling mitochondrial dysfunction has been difficult mainly due to unique features of mitochondrial genetics. Here we discuss some of the most important mouse models generated so far and lessons learned from them., S. A. Dogan, A. Trifunovic., and Obsahuje bibliografii a bibliografické odkazy