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11.
Sub Sunoo Katsumi Asano Fumiyuki Mitsumori 《European journal of applied physiology and occupational physiology》1996,74(4):305-310
We measured ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and the intracellular pH in rat hindlimb muscles during submaximal isometric exercise with various O2 deliveries using31P nuclear magnetic resonance spectroscopy (31P NMR) to evaluate changes in energy metabolism in relation to O2 availability. Delivery of O2 to muscles was altered by controlling the fractional concentration of inspired oxygen (F
IO2) at 0.50, 0.28, 0.21, 0.11 and 0.08 with monitoring partial pressure of oxygen and carbon dioxide, and bicarbonate at the femoral artery. The steady-state ratio of PCr : (PCr + Pi) during exercise decreased as a function ofF
IO2 even at 0.21. Significant acidification of the intracellular pH during exercise occurred at 0.08F
IO2. Change in the PCr : (PCr + Pi) ratio demonstrated that the oxidative capacity, i.e. the maximal rate of the oxidative phosphorylation reaction, in muscle was not limited by O2 delivery at 0.50F
IO2, but was significantly limited at 0.21F
IO2 or below. Change in the intracellular pH at 0.08F
IO2 could be interpreted as an increase in lactate, suggesting activation of glycolysis. Correlation between the PCr : (PCr + Pi) ratio and the intracellular pH revealed the existence of a critical PCr : (PCr + Pi) ratio and pH for glycolysis activation at around 0.4 and 6.7, respectively. 相似文献
12.
Katsumi Mominoki Noriko Nakagawa-Tosa Masami Morimatsu Bunei Syuto Masayuki Saito 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1995,110(4):785-789
Haptoglobin (Hp), a hemoglobin-binding protein in plasma, consists of α and β subunits and has a tetra-chain arrangement (β-α-α-β) connected by disulfide bridges in most mammals so far examined. Dog Hp has been reported to be unique compared with other Hps in respect that (1) the two αβ units are joined by a non-covalent interaction rather than a disulfide bridge and (2) the α chain has an oligosaccharide-binding sequence (Asn-X-Ser/Thr) and is glycosylated. To determine whether the unique structures of dog Hp are common in the Carnivora, we purified Hps from sera of bear and cat, and analyzed their subunit structure and partial amino acid sequences. The analyses by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under both reducing and non-reducing conditions, revealed that bear and cat Hps have similar subunit arrangements to dog Hp, suggesting the absence of a disulfide bridge between two α chains. This was confirmed by amino acid sequence analysis of the α chains: that is, Cys15 participating in the inter-α chain disulfide bridge was replaced by Val in bear or Leu in cat and dog. Thus, the unique subunit arrangement of Hp reported in dog may be common in the Carnivora. In contrast to dog Hp, however, α chains of bear and cat Hps were found not to have the typical oligosaccharide binding sequence on their α chains and were not glycosylated. 相似文献
13.
Mayumi Nishikata Aki Nakai Hitomi Fushida Keishiro Miyake Takaichi Arita Ken Iseki Katsumi Miyazaki Akikazu Nomura 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,612(2)
A method is described for the simultaneous determination of (+)- and (−)-homochlorcyclizine (HCZ) in human urine by high-performance liquid chromatography on a chiral stationary phase of ovomucoid-bonded silica. The pH of the buffer and organic modifier in the mobile phase markedly affected the chromatographic separation. A mobile phase of methanol—0.02 M acetate buffer (pH 4.7) (25:75, v/v) at a flow-rate of 1.0 ml/min was used for the urine assays. The ultraviolet absorption was monitored at 240 nm, and diphenhydramine was employed as the internal standard for the quantitation. (+)-HCZ, (−)-HCZ and the internal standard were eluted at retention times of 15, 25 and 8 min, respectively. The limit of determination for HCZ enantiomers was ca. 50 ng/ml of urine. One of the metabolites in human urine, which was a quaternary ammonium-linked glucuronide, could also be determined in a manner similar to unchanged HCZ after β-glucuronidase hydrolysis. A pharmacokinetic study was conducted with three healthy volunteers, who each received a single oral dose of racemic HCZ (20 mg). Distinct differences were found between the two enantiomers, particularly in the metabolic process, that is, the urinary excretion as (−)-HCZ-glucuronide within 48 h was ca. four times higher than that of the (+)-isomer. This method should be very useful for enantioselective pharmacokinetic studies of HCZ. 相似文献
14.
Douglas E Bassett Jr Munira A Basrai Carla Connelly Katherine M Hyland Katsumi Kitagawa Melanie L Mayer Dwight M Morrow Andrew M Page Vicente A Resto Robert V Skibbens Philip Hieter 《Current opinion in genetics & development》1996,6(6):763-766
The completion of the genome sequence of the budding yeast Saccharomyces cerevisiae marks the dawn of an exciting new era in eukaryotic biology that will bring with it a new understanding of yeast, other model organisms, and human beings. This body of sequence data benefits yeast researchers by obviating the need for piecemeal sequencing of genes, and allows researchers working with other organisms to tap into experimental advantages inherent in the yeast system and learn from functionally characterized yeast gene products which are their proteins of interest. In addition, the yeast post-genome sequence era is serving as a testing ground for powerful new technologies, and proven experimental approaches are being applied for the first time in a comprehensive fashion on a complete eukaryotic gene repertoire. 相似文献
15.
Chloroplast division in Nannochloris bacillaris Naumann (Chlorophyta) was examined by electron microscopy after preparation of samples by freeze-substitution. A pair of belts appeared on the surface of the outer and inner envelope membranes at the middle of the chloroplast. These belts seemed to be constructed of thin fibrils that run parallel to the longitudinal direction of the belts. The outer fibrillar belt increased in width as the constriction of the chloroplast advanced. It appears that the fibrillar belt is the division apparatus of the chloroplast. It encircles the chloroplast and finally divides the chloroplast in two as the diameter of the belt decreases. 相似文献
16.
Miyake Ken; Ohtomi Michiko; Yoshizawa Hisamitsu; Sakamoto Yohko; Nakayama Katsumi; Okada Mitsumasa 《Plant & cell physiology》1995,36(1):109-113
Several water-soluble pigments were purified from gametangiaof Bryopsis maxima by liquid chromatography and characterizedby pyridylamination and high-performance anion-exchange chromatography.The structure of the main red pigment is proposed based on thedata of infrared spectrum, Mass spectrum, 1H and 13C NMR spectraand pyridylamino analysis. As a consequence, this pigment containeda tetrapyrrole with phytol and a sugar chain comprised of xyloseand glucose. The sequence of the sugars in the chain was determinedbased on its Mass spectrum. The pigment was similar to chlorophyll-originpigments observed in other plants. No aldehyde group, however,was present at C5 in the open tetrapyrrole chain. (Received August 3, 1994; Accepted November 10, 1994) 相似文献
17.
Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs 总被引:2,自引:0,他引:2
Kobayashi Tsutomu; Tashiro Katsumi; Yamamoto Ken; Nitta Shunichi; Ohmura Shigeo; Suzuki Yasuhiro 《Journal of applied physiology》1997,83(6):1849-1856
Kobayashi, Tsutomu, Katsumi Tashiro, Ken Yamamoto, ShunichiNitta, Shigeo Ohmura, and Yasuhiro Suzuki. Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs. J. Appl. Physiol. 83(6):1849-1856, 1997.To investigate the effects of surfactantproteins B (SP-B) and C (SP-C) on lung mechanics, we compared tidal andstatic lung volumes of immature rabbits anesthetized with pentobarbitalsodium and given reconstituted test surfactants (RTS).With a series of RTS having various SP-B concentrations (0-0.7%)but a fixed SP-C concentration (1.4%), both the tidal volume with25-cmH2O insufflation pressure and the static volume deflated to5-cmH2O airway pressure increased, significantly correlating with the SP-B concentration: the former increased from 6.5 to 26.0 ml/kg (mean), and the latter increased from6.4 to 31.8 ml/kg. With another series of RTS having afixed SP-B concentration (0.7%) but various SP-C concentrations(0-1.4%), the tidal volume increased from 5.1 to 24.8 ml/kg,significantly correlating with the SP-C concentration, whereas thestatic volume increased from 3.4 to 32.0 ml/kg, the ceiling value, inthe presence of a minimal concentration of SP-C (0.18%). Inconclusion, certain doses of SP-B and SP-C were indispensable foroptimizing dynamic lung mechanics; the static mechanics, however,required significantly less SP-C. 相似文献
18.
The RAD51 gene is a eukaryotic counterpart of the Escherichia coli recA gene which is involved in genetic recombination. Two distinct Xenopus laevis RAD51 cDNA clones (XRAD51.1 and XRAD51.2) were isolated from an oocyte cDNA library using the human RAD51 cDNA (HsRAD51) as a probe. Sequence analysis revealed that 98.2% of the amino-acid residues were identical between XRAD51.1 and XRAD51.2, and that both were 95% identical to HsRAD51. Both of the XRAD51 genes were expressed at a higher level in ovary and testis than in other somatic tissues, suggesting their involvement in meiotic recombination. The expression of XRAD51.1 was about eightfold in excess of that of XRAD51.2 in all of the tissues examined. Analysis of the rates of synonymous substitution in the coding sequences of the two XRAD51 suggests that these two genes diverged about 50 million years ago. The structural similarities of the XRAD51 proteins to RecA in E. coli and Rad51 in yeasts or vertebrates are discussed. 相似文献
19.
We have found that biotin is synthesized in many species of cultured plant cells, e.g. Lavandula vera Labiatae), Nicotiana tabacum (Solanaceae) and Glycine max Leguminosae). Cultured green L. vera cells grown under light contained the greatest amounts of free biotin of the cells studied although the specific amounts varied among the cell lines. Cell lines were selected after their free biotin contents had been analysed. Cells containing large amounts of free biotin were cultured repeatedly, analysed and reselected. Lines with high levels of free biotin were obtained from cells which survived on a medium containing pimelic acid and l-alanine or from gamma irradiated cells. One L. vera cell line obtained from irradiated cells contained seven times the amount of free biotin found in the original unselected cultured cells and four and a half times that found in the leaves. 相似文献
20.
Blue light-induced unrolling of second leaves in rice plants(Oryza sativa L.) was studied. Light in wavelengths of 400500nm was most effective for the induction of unrolling, whilethat of 500800 nm had no influence. This blue light actionon unrolling was observed for both dark and light grown seedlings.Several hours of irradiation was required for the inductionof unrolling at a relatively high intensity. Red light had noinfluence on the blue light action. We concluded that blue lightaction on the unrolling of rice leaves is not mediated by thephytochrome system, but by a high energy blue light reactionwhich differs from the unrolling of wheat and barley leaves. (Received March 3, 1979; ) 相似文献