Forward and backward masking in the presence of a continuous noise floor.
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Biomedical subjects
Publications and source records attributed to M Pavel.
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The evaluation of the results of the oxygen free radicals (RLO2) formation is a current subject in biology and medicine. The oxidative stress, which is the altering of the balance between the higher activity of oxygen and the enzymatic or nonenzymatic protection systems, may be one of the causes that starts and aggravates a disease. In this context, the supplementation of the diet with selenium, superoxide dismutase, vitamins A, C, E, is considered a primary prevention measure (for the apparently healthy persons) and a secondary one (for those with advancing forms of disease) that is both efficient and modern by utilization of some "drug-food" products. The transversal study realized on a group of 39 blood donors presence of the cardiovascular risk determined by the raising of the prevalence of some atherogenic factors (active smoking, hypercholesterolemia) which is also expressed by the lowering of the level of some oxidative stress indicators (glutathione peroxidase--GSH-Px < 0.139 moli/ml and catalase < 2.20 U/ml). The simultaneous low intake of selenium from the central drinking water supplies in the city of Iaşi (0.1-1 g/l) has permitted us to consider necessary the diet supplementation both with foods rich in vitamins with an antioxidant role and with specific medication with selenium, as a protective micro-element.
Liposome research is a thriving field at the confluence of biophysics, cell biology and medicine. The principal medical application of liposomes is based on their potential to act as carriers for a broad spectrum of drugs and other agents, including antigens with or without immunomodulators in vaccination. Treatment of peritoneal macrophages of rats with small unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC SUV) potentiated their activation for tumor cell lysis by endotoxins. The measurement of the fluorescence anisotropy of diphenylhexatriene showed a phase transition. No phase transition was observed in the rough endoplasmic reticulum membranes of macrophages either treated or not treated with cholesterol/DPPC SUV. The synergistic effect of DPPC SUV on the tumoricidal activity of macrophages induced by endotoxins appears to be correlated with the changes in the properties of the rough endoplasmic reticulum membranes. Both effects were transient; they had the same kinetics of induction and reversion.
Provision of a better understanding of the pathogenic pathways underlying injured sugar metabolism during stress should ideally translate into a more rational approach to the provision of nutritional support. Patients with burns, trauma, severe injuries or infections commonly develop a hypermetabolic state that is associated with several changes in carbohydrate metabolism. The hypermetabolic state is induced either by the area of injury and by organs involved in the immunologic response to stress; further it determines a glycemic milieu which will be directed toward satisfaction of the requirements for glucose as an energy support.
In continuing experiments to determine the basis of presynaptic modulation, rat cortical synaptosomes were employed and transmembrane calcium fluxes were determined with a metalocromophoric dye, Arsenazo III. The intracellular free Ca2+ concentrations show complex fluctuations in time and space in response to a variety of stimuli, acting as a pluripotent signal for many neuronal functions. Depolarisation of synaptosomes by K+ 20 mM determined calcium influx in cortical synaptosomes, mainly mediated by the Q type Ca2+ channels, with a minor participation of the N type channels. The administration protocol for the polyamines, revealed that agmatine, spermine, spermidine, putresceine and cadaverine reduce, in variable proportions, the K(+)-induced Ca2+ influx, in synaptosomal preparations. The results plead for the ability of agmatine and spermine to modulate Ca2+ fluxes in synaptosomes, both from the interior and exterior side. Moreover, rigidization of the synaptosomal membrane (by cholesterol-enriched liposomes administration) do not significantly influences K(+)-induced Ca2+ influx in synaptosomal preparations.
The professional poisoning with acrylonitrile of some subjects induced a significant decrease of reduced glutathione (81.30%), redox ratio reduced glutathione/oxidized glutathione (90.74%) and "Benzi-redox index" (55.84%) but an increase of oxidized glutathione level (112.6%) as compared to normal controls (100%). This proves the occurrence, in time, of the cellular oxidative stress and/or were obtained.
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