[Analysis of protein concentration in the urine of children with metabolic nephropathy, crystal-calcium crystalluria].

We compared the efficacy of a routine sulphosalycilic acid method and a new technique of pirogallolic red staining for urine protein assay in children with metabolic nephropathy, crystal-calcium crystaluria. The former method was found ineffective in proteinuria diagnosis in children with metabolic nephropathy. The pirogallolic method appeared more effective as it detects microproteinuria and therefore allows accurate diagnosis, control of its treatment and finally to improve the results of therapeutic and prophylactic measures.

[The role of intracellular Ca(2+) pools in the regulation of protoplast volume. Effect of red light on the Ca(2+) mobilization in cytoplasm of Arabidopsis cells]. / Rol' vnutrikletochnykh pulov Ca(2+) v reguliatsii ob''ema protoplastov. Vliianie krasnogo sveta na mobilizatsiiu Ca(2+) v tsitoplazme kletok Arabidopsis.

The changes in cytosol Ca2+ concentration associated with the shrinkage of Arabidopsis cells induced by the inhibitor of Ca(2+)-ATPase, cyclopiazonic acid and the Ca2+ ionophore ionomycin were monitored using the fluorescence of Ca(2+)-sensitive probe chlortetracycline hydrochloride. It was found that these compounds elicited a substantial decrease in fluorescence intensity closely associated with Ca(2+)-release from the intracellular stores to the cytoplasm. The release of Ca2+ from the intracellular depots was accompanied by decrease of plant cell volume. Thapsigargin and 2,5'-ditert-butyl-1,4-benzohydroquinone (highly specific inhibitors of Ca(2+)-ATPase of endoplasmic reticulum) resulted in much weaker changes than cyclopiazonic acid did. It was also found with the help of the same technique that red light (lambda = 660 nm) illumination induced a similar Ca2+ release from the intracellular stores. Moreover, the amplitudes of light-induced fluorescence responses registered in mutant plants differing in the content of phytochrome A (phyAOX) and phytochrome B (phyBOX) were much higher than those registered in wild-type of Arabidopsis.

[Mathematical model of oscillations in mammalian erythrocytes. The role of calmodulin-dependent Ca-activated Ca-pump]. / Matematicheskaia model' kolebanii v éritrotsitakh mlekopitaiushchikh.Rol' kal'modulinzavisimogo Ca-aktiviruemogo Ca-nasosa.

A kinetic model of ionophore-induced oscillation of ion fluxes in mammalian erythrocytes is proposed. The model is based on the regulation by Ca2(+)-ions and calmodulin of (Ca2(+) + Mg2+)-dependent ATPase of erythrocytes. The results obtained are in a good agreement with the experimental data available.

[K+,H+ and Cl- fluxes across erythrocyte membrane irradiated with radio frequency electromagnetic fields]. / Issledovanie potokov K+,H+ i Cl- cherez membranu éritrotsitov, obluchennykh élektromagnitnym izlucheniem radiochastotnogo diapazona.

The effect of 460 MHz microwave radiation on the ion-transporting properties of the isolated rat erythrocytes was studied with the use of K+, H+ and Cl(-)-selective electrodes. In comparison with the control cells kept at 0 degree C the most significant changes were observed in the K+ transport system. Particularly, microwave radiation (specific absorbed rate 280 W/kg) caused an increased loss of K+ during treatment and 2-fold decrease in the rate of K+ efflux from the irradiated erythrocytes, when the latter were incubated in the isoosmotic, unbuffered sucrose. The same changes were observed when the erythrocytes were conventionally heated up to 39 degrees C for 20 minutes. It is concluded that high levels of microwave radiation cause temperature-induced changes of the membrane structure resulting in alterations in potassium transport across the membrane.

[Substrate inhibition in the tricarboxylic acid cycle]. / Substratnoe ugnetenie v tsikle trikarbonovykh kislot.

It has been shown in the experiments on rat liver mitochondria under glucose hexo-kinase load that excess of substrates of (1-20 mM) pyruvate, acetate, propionate, pent-4-enoate and malate may induce oxidation of NAD(P)H and inhibition of mitochondrial respiration (by 20-50% and more) due to a decreased rate of hydrogen production by tricarboxylic acid cycle. It has been concluded from the analysis of mathematical models and metabolite-testings which remove this inhibition that for pyruvate and acetate this inhibition is an autocatalytic one. It is related to a decreased level of CoA and oxaloacetate due to the formation of "traps" such as acetyl-CoA and alpha-kotoglutarate. For propionate and pent-4-enoate in the bicarbonate-free medium suppression of the flux in the cycle is concerned with a decreased level of CoA, acetyl-CoA and succionoyl CoA due to the accumulation of propionyl-CoA. It seems to be also concerned with the inhibition of citrate-synthetase and alpha-ketoglutarate-dehydrogenase by propionyl-CoA. Malate (in the presence of malonate) can inhibit respiration at the expense of direct inhibition of citrate-synthetase.

[Stabilization of delta mu H+ in Escherichia coli upon K+ and Na+ transmembrane gradient dissipation]. / Stabilizatsiia del'ta mu H+ i Escherichia coli pri rasseivanii transmembrannykh gradientov K+ i Na+.

The role of Na+/K+ gradients as a stabilizing factor for the energetics of bacterial cell has been evaluated. It was shown that in the presence of a Na+/K+ gradient across the membrane the cells of the unc mutant of E. coli retain their motility for some time under anaerobic conditions. This time coincides with that of dissipation of the K+ gradient by the bacteria during the anaerobiosis. A switch-off of the generator (respiration) entails a collapse of the membrane potential (delta psi). The anaerobiosis-induced efflux of K+ from the cells is uncoupler-stimulated, thus suggesting that the K+ efflux has an electrogenic nature and stabilizes delta psi. The use of valinomycin allowed to establish a correlation between the rate of K+ efflux, the delta psi value and the rate of bacterial motion under anaerobic conditions. After the onset of anaerobiosis the level of delta psi decreases faster as the concentration of extracellular K+ increases. It was shown that the capacity of the K+ gradient as te delta psi buffer depends on the pH of the medium and that artificial Na+ gradient can energize the E. coli cells by Na+/K+ exchange.