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101.
102.
The duration of the preautomatic pause as a function of sinoatrial node, the type of pacemaker cells, acetylcholine concentration,
the duration of high-frequency stimulation, and the conductivity of gap junctions has been studied. It was found that the
preautomatic pause in peripheral pacemakers occurs at a higher concentration of acetylcholine as compared with central pacemakers.
The dependence of the duration of the preautomatic pause on the gap junction conductivity is a nonlinear one. 相似文献
103.
R. R. Aliev 《Biophysics》2008,53(6):645-647
The effect of periodic stimulation of the vagus nerve on the activity of the central cell of the sinoatrial node has been simulated. The regions of synchronization and desynchronization have been revealed, and the phase shift at different stimulation frequencies has been estimated. The positive chronotropic effect has been shown to occur at some frequencies of stimulation. 相似文献
104.
M Fossi K Ahlsten T Pohjanvirta M Anttila T Kokkonen TK Jensen M Boye A Sukura K Pelkola S Pelkonen 《Acta veterinaria Scandinavica》2005,46(4):257
A hippurate-negative biovariant of Brachyspira pilosicoli (B. pilosicoli
hipp-) is occasionally isolated in diarrhoeic pigs in Finland, often concomitantly with hippurate-positive B. pilosicoli or Lawsonia intracellularis. We studied pathogenicity of B. pilosicoli
hipp- with special attention paid to avoiding co-infection with other enteric pathogens. Pigs were weaned and moved to barrier
facilities at the age of 11 days. At 46 days, 8 pigs were inoculated with B. pilosicoli
hipp- strain Br1622, 8 pigs were inoculated with B. pilosicoli type strain P43/6/78 and 7 pigs were sham-inoculated. No signs of spirochaetal diarrhoea were detected; only one pig, inoculated
with P43/6/78, had soft faeces from day 9 to 10 post inoculation. The pigs were necropsied between days 7 and 23 after inoculation.
Live pigs were culture-negative for Brachyspira spp., but B. pilosicoli
hipp- was reisolated from necropsy samples of two pigs. The lesions on large colons were minor and did not significantly differ
between the three trial groups. In silver-stained sections, invasive spirochaetes were detected in colonic mucosae of several
pigs in all groups. Fluorescent in situ hybridisation for genus Brachyspira, B. pilosicoli and strain Br1622 was negative. However, in situ detection for members of the genus Leptospira was positive for spirochaete-like bacteria in the colonic epithelium of several pigs in both infected groups as well as in
the control group. L. intracellularis, Salmonella spp., Yersinia spp. and intestinal parasites were not detected. The failure of B. pilosicoli strains to cause diarrhoea is discussed with respect to infectivity of the challenge strains, absence of certain intestinal
pathogens and feed and management factors. 相似文献
105.
Activation and redistribution of c-jun N-terminal kinase/stress activated protein kinase in degenerating neurons in Alzheimer's disease 总被引:11,自引:0,他引:11
Zhu X Raina AK Rottkamp CA Aliev G Perry G Boux H Smith MA 《Journal of neurochemistry》2001,76(2):435-441
Cellular responses to increased oxidative stress appear to be a mechanism that contributes to the varied cytopathology of Alzheimer's disease (AD). In this regard, we suspect that c-Jun N-terminal kinase/Stress activated protein kinase (JNK/SAPK), a major cellular stress response protein induced by oxidative stress, plays an important role in Alzheimer disease in susceptible neurons facing the dilemma of proliferation or death. We found that JNK2/SAPK-alpha and JNK3/SAPK-beta were related to neurofibrillary pathology and JNK1/SAP-Kgamma related to Hirano bodies in cases of AD but were only weakly diffuse in the cytoplasm in all neurons in control cases and in non-involved neurons in diseased brain. In this regard, in hippocampal and cortical regions of individuals with severe AD, the activated phospho-JNK/SAPK was localized exclusively in association with neurofibrillar alterations including neurofibrillary tangles, senile plaque neurites, neuropil threads and granulovacuolar degeneration structures (GVD), completely overlapping with tau-positive neurofibrillary pathology, but was virtually absent in these brain regions in younger and age-matched controls without pathology. However, in control patients with some pathology, as well as in mild AD cases, there was nuclear phospho-JNK/SAPK and translocation of phospho-JNK/SAPK from nuclei to cytoplasm, respectively, indicating that the activation and re-distribution of JNK/SAPK correlates with the progress of the disease. By immunoblot analysis, phospho-JNK/SAPK is significantly increased in AD over control cases. Together, these findings suggest that JNK/SAPK dysregulation, probably resulting from oxidative stress, plays an important role in the increased phosphorylation of cytoskeletal proteins found in AD. 相似文献
106.
107.
108.
Is oxidative damage the fundamental pathogenic mechanism of Alzheimer's and other neurodegenerative diseases? 总被引:10,自引:0,他引:10
Perry G Nunomura A Hirai K Zhu X Pérez M Avila J Castellani RJ Atwood CS Aliev G Sayre LM Takeda A Smith MA 《Free radical biology & medicine》2002,33(11):1475-1479
In less than a decade, beginning with the demonstration by Floyd, Stadtman, Markesbery et al. of increased reactive carbonyls in the brains of patients with Alzheimer's disease (AD), oxidative damage has been established as a feature of the disease. Here, we review the types of oxidative damage seen in AD, sites involved, possible origin, relationship to lesions, and compensatory changes, and we also consider other neurodegenerative diseases where oxidative stress has been implicated. Although much data remain to be collected, the broad spectrum of changes found in AD are only seen, albeit to a lesser extent, in normal aging with other neurodegenerative diseases showing distinct spectrums of change. 相似文献
109.
110.
T V Krylova V M Fomushkin M N Aliev M L Oparin M N Ismailov 《Nauchnye doklady vysshe? shkoly. Biologicheskie nauki》1988,(1):50-53
The kind of the regulating agent for the quantitative control of the epidemically dangerous species depends on the concrete tasks. The poison of the critical action causes a strong, but short-time effect. The pesticide inhibiting the reproductive system of the rodents exerts long and profound influence on the population structure. 相似文献