Chronic sojourn in hypoxic environment results in the structural remodeling of peripheral pulmonary arteries and pulmonary hypertension. We hypothesize that the pathogenesis of changes in pulmonary vascular structure is related to the increase of radical production induced by lung tissue hypoxia. Hypoxia primes alveolar macrophages to produce more hydrogen peroxide. Furthermore, the increased release of oxygen radicals by other hypoxic lung cells cannot be excluded. Several recent reports demonstrate the oxidant damage of lungs exposed to chronic hypoxia. The production of nitric oxide is high in animals with hypoxic pulmonary hypertension and the serum concentration of nitrotyrosine (radical product of nitric oxide and superoxide interaction) is also increased in chronically hypoxic rats. Antioxidants were shown to be effective in the prevention of hypoxia induced pulmonary hypertension. We suppose that the mechanism by which the radicals stimulate of the vascular remodeling is due to their effect on the metabolism of vascular wall matrix proteins. Non-enzymatic protein alterations and/or activation of collagenolytic matrix metalloproteinases may also participate. The presence of low-molecular weight cleavage products of matrix proteins stimulates the mesenchymal proliferation in the wall of distal pulmonary arteries. Thickened and less compliant peripheral pulmonary vasculature is then more resistant to the blood flow and the hypoxic pulmonary hypertension is developed., J. Herget, J. Wilhelm, J. Novotná, A. Eckhardt, R. Vytášek, L. Mrázková, M. Ošťádal., and Obsahuje bibliografii
The purpose of the study was to check whether hypoxia of corneal tissue increases the collagenolytic activity due to release of reactive oxygen and nitrogen species. Rats were exposed to hypoxia 10 % O2 for 4, 14, and 21 days. The radical tissue injury was measured by the level of nitrotyrosine and changes in the lipoperoxide-related fluorophores. Collagen protein composition was analyzed by slab gel electrophoresis. The activity of gelatinolytic enzymes was studied using the zymography. The vascularization of the corneas was measured. We found no differences in the corneal tissue in the gel electrophoretic profile of collagenous proteins and gelatinolytic activity between normoxic and hypoxic rats. We did not find any sign of radical tissue injury. There were no changes in the vascularization of corneas after exposition to hypoxia. The environmental 10 % hypoxia does not induce radical tissue injury and an increase of collagenolytic activity in the rat cornea., G. Mahelková, J. Korynta, A. Moravová, J. Novotná, R. Vytášek, J. Wilhelm., and Obsahuje bibliografii a bibliografické odkazy
Nitric oxide (NO) is an important signalling molecule with diverse physiological functions in plants. In plant cell, it is synthesised in several metabolic ways either enzymatically or nonenzymatically. Due to its high reactivity, it could be also cytotoxic in dependence on concentration. Such effects could be also mediated by NO-derived compounds. However, the role of NO in photosynthetic apparatus arrangement and in photosynthetic performance is poorly understood as indicated by a number of studies in this field with often conflicting results. This review brings a short survey of the role of exogenous NO in photosynthesis under physiological and stressful conditions, particularly of its effect on parameters of chlorophyll fluorescence. and D. Procházková ... [et al.].
The protective effect of therapeutic hypothermia in cardiac arrest survivors (CAS) has been previously well documented. Animal studies have indicated that attenuation of tissue oxidative stress (OS) may be involved in the mechanisms that lead to the beneficial effect of hypothermia. The extent of OS and nitric oxide (NO) production in adult CAS treated with endovascular hypothermia is, however, unknown. A total of 11 adult patients who experienced cardiac arrest out of hospital were included in the present study, and all were treated with mild hypothermia using the Thermogard XP (Alsius, USA) endovascular system. A target core temperature of 33 °C was maintained for 24 hours, with a subsequent rewarming rate of 0.15 °C per hour, followed by normothermia at 36.8 °C. Blood samples for the measurement of nitrotyrosine and nitrate/nitrite levels were drawn at admission and every 6 hours thereafter for two days. During the hypothermic period, the levels of nitrotyrosine and nitrates/nitrites were comparable with baseline values. During the rewarming period, serum levels of both parameters gradually increased and, during the normothermic period, the levels were significantly higher compared with hypothermic levels (nitrotyrosine, P<0.001; nitrates/nitrites, P<0.05). In our study, significantly lower levels of nitrotyrosine and nitrates/nitrites were demonstrated during hypothermia compared with levels during the normothermic period in adult CAS. These data suggest that attenuation of OS and NO production may be involved in the protective effect of hypothermia in adult CAS., A. Krüger ... [et al.]., and Obsahuje seznam literatury