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21.
Responses in muscle sympathetic activity to acute hypoxia in humans   总被引:10,自引:0,他引:10  
Responses in muscle sympathetic activity (MSA) to acute hypoxia were studied in 13 healthy male subjects under hypobaric hypoxic conditions at a simulated altitude of 4,000, 5,000, and 6,000 m. Efferent postganglionic MSA was recorded directly with a tungsten microelectrode inserted percutaneously into the tibial nerve. Heart rate (HR) and respiratory rate (RR) were counted respectively from the R wave of an electrocardiogram and from the respiratory tracing recorded by the strain-gauge method. The average values of the MSA burst rate and total activity of MSA (burst rate x mean burst amplitude) at 4,000, 5,000, and 6,000 m were 36.4 +/- 2.6, 39.1 +/- 3.1, and 40.2 +/- 4.2 (SE) bursts/min and 616 +/- 138, 794 +/- 190, and 764 +/- 227 arbitrary units, respectively. These values were significantly higher than the values of 27.1 +/- 2.9 bursts/min and 446 +/- 28 at sea level. HR increased significantly at altitudes, but RR did not show significant change. Under severe hypoxic conditions beyond 5,000 m, there were large interindividual differences in the MSA responsiveness to hypoxia. The results indicate that MSA is activated under hypoxia by stimulating the chemoreceptors. However, the central controlling mechanisms that would be affected by hypoxia may also influence the MSA responsiveness under severe hypoxia.  相似文献   
22.
Summary (±)-Tricarbonyl 6-3-methylbenzyl alcohol)chromium was resolved to of 100%e.e. and of 92%e.e. by lipase-catalyzed transesterifications arranged in homotopic and heterotopic double resolutions.  相似文献   
23.
Summary Two-dimensional (2D)1H NMR experiments using deuterium labeling have been carried out to investigate the solution structure of ribonuclease HI (RNase HI) fromEscherichia coli (E. coli), which consists of 155 amino acids. To simplify the1H NMR spectra, two fully deuterated enzymes bearing several prototed amino acids were prepared from an RNase HI overproducing strain ofE. coli grown in an almost fully deuterated medium. One enzyme was selectively labeled by protonated His, He. Val. and Leu. The other was labeled by only protonated His and Ile. The 2D1H NMR spectra of these deuterated R Nase H1 proteins, selectively labeled with protonated amino acids, were much more simple than those of the normally protonated enzyme. The simplified spectra allowed unambiguous assignments of the resonance peaks and connectivities in COSY and NOESY for the side-chain protons. The spin-lattice relaxation times of the side-chain protons of the buried His residue of the deuterated enzyme became remarkably longer than that of the protonated enzyme. In contrast, the relaxation times of the side-chain protons of exposed His residues remained essentially unchanged.  相似文献   
24.
25.
Change in the localization of the antigen recognized by the proteinuria-inducing monoclonal antibody (MA) 5-1-6 in experimental nephrosis was studied by indirect and biotin-avidin immunofluorescence, and immunoperoxidase at light and electron microscopical levels. The proteinuric state was induced by the administration of the aminonucleoside of puromycin (PAN) or adriamycin. The antigen decreased in quantity and/or its distribution changed with an increase in the amount of protein excreted in both experimental models. Recovery from the alterations observed during the development and proteinuria appeared to occur when PAN-induced proteinuria subsided. This antigenic molecule may thus be essential for maintaining the normal permselectivity of glomerular capillary walls.  相似文献   
26.
27.
Cytochrome c oxidase of Nitrosomonas europaea reacts with not only the native cytochrome c (N. europaea cytochrome c-552) but also horse and yeast cytochromes c. The effects on its reactivity of various reagents were very different between the reactions with the native and eukaryotic cytochromes c as the electron donors. The oxidation of eukaryotic ferrocytochrome c by the oxidase was activated by addition of anionic detergents such as sodium dodecyl sulfate and sodium cholate, and anionic phospholipids such as cardiolipin, phosphatidylserine, phosphatidylinositol, and phosphatidylethanolamine, while the reaction was not activated by Triton X-100, Tween 20, or phosphatidylcholine. However, the reaction with the native cytochrome c of the enzyme was hardly affected by any of the detergents and phospholipids mentioned above, while it was activated by the presence of poly-L-lysine.  相似文献   
28.
The anticoccidial activity of an uridine analog, 1-(beta-D-ribofuranosyl)-2(1H)-pyrazinone 4-oxide (emimycin riboside), against five species of chicken Eimeria was tested individually in battery experiments. With 16 ppm of the compound in feed, marked anticoccidial activity was obtained against Eimeria tenella, E. necatrix, E. acervulina, E. maxima, and E. brunetti. The last named species was more drug-sensitive than the others--dietary levels of at least 8 ppm of the drug exhibited good protection and eliminated practically all clinical signs. The battery tests with delayed and restricted medications showed that emimycin riboside affected the development of parasites in first and second generation schizogony of the life cycle of E. tenella.  相似文献   
29.
Circadian variations in the activities of aldehyde dehydrogenase (ALDH) isozymes in the subcellular fractions of the brain and liver were investigated in male and female mice of C57BL/6J strain. The rhythms in high Km-ALDH activities of brain and liver mitochondrial fractions which existed in ordinary light-dark cycle were not observed in animals maintained in the continuous darkness for two weeks. The rhythms in high Km-ALDH activities of hepatic soluble and microsomal fractions existed in both ordinary cycle and total darkness but the rhythmic phases were different. In the low Km-ALDH activity of hepatic mitochondrial fraction, the circadian rhythm was similar in two lighting conditions. There was sex difference in the existence of the circadian rhythm. It seems that the ALDH activity of mice is influenced by light-dark cycle and sex hormones.  相似文献   
30.
Spectra of chloroperoxidase compounds II and III   总被引:2,自引:0,他引:2  
Chloroperoxidase was present as Compound II during the peroxidatic oxidation of ascorbic acid. Compound III (oxy-form) was formed when excess hydrogen peroxide was added to Compound II. By decreasing the temperature it was possible to measure the spectra of Compounds II and III in the Soret and visible regions. Each spectrum was found to resemble that of the corresponding form of lactoperoxidase. Under the experimental conditions, chloroperoxidase Compound III was apparently converted to Compound II in parallel with the decomposition of hydrogen peroxide and finally to the ferric enzyme.  相似文献   
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