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Biomedical subjects

H Yamamura

Publications and source records attributed to H Yamamura.

At least 397 records · Page 22Linked to original sources
PubMed1980

Carcinoembryonic antigen in gastric juice as an aid in diagnosis of early gastric cancer.

The levels of carcinoembryonic antigen (CEA) in the serum and gastric juice of 58 patients with gastric cancer were determined by radioimmunoassay. The level of serum CEA was not a satisfactory indicator of gastric cancer: it was elevated in only 19.4% of the cases of advanced and unresectable cancer and 4.5% of cases of early cancer examined. However, the CEA level in the gastric juice was significantly higher in patients with gastric cancer than in normal subjects or patients with benign gastric diseases: increased CEA concentrations and outputs in the gastric juice were observed in 54.5% and 40.1%, respectively, of the patients with early gastric cancer, and in 52.9% and 50.0%, respectively, of the patients with advanced gastric cancer. The gross type of gastric cancer had no influence on the gastric CEA level, but the CEA level in the gastric juice tended to be high when the tumors were large, or when they had little or no glandular structure or high mucus-secreting activity.

Biopsy↗
PubMed1980

Enzymic determination of serum oxalate.

A new colorimetric, enzymic method for determination of serum oxalate is described using oxalate oxidase from barley seedlings. This method, based on a specific reaction of oxalate with oxidase is rapid, simple and precise. The percentage recoveries of oxalate added to serum ranged from 91.5 to 103. The oxalate content in the serum obtained from 50 healthy non-fasting donors varied from 0.06 mg/dl to 0.41 mg/dl. The proposed method showed a good correlation with a chemical method.

Colorimetry↗
PubMed1980

Inhibitory and stimulatory effects of guanyl-5'-yl imidodiphosphate on the adenylate cyclase activity of rat synaptosomal fractions.

Guanyl-5'-yl imidodiphosphate (Gpp(NH)p), a nucleotide phosphohydrolase-resistant analog of GTP, caused inhibitory and stimulatory effects on the basal adenylate cyclase activity of rat synaptosomal fractions when manganese was present in the assay mixture, whereas the nucleotide caused only a stimulatory effect when magnesium was employed. In the presence of manganese, the inhibitory and stimulatory effects of Gpp(NH)p could be seen at around concentrations of 10(-7) M and 10(-4) M Gpp(NH)p, respectively. The inhibitory and stimulatory effects of Gpp(NH)p were both antagonized competitively by GTP; these effects of the analog were the opposite of those observed with GTP, which was stimulatory and inhibitory for fat call adenylate cyclase at 10(-7) M and 10(-4) M, respectively (Yamamura, H., Lad, P.M., and Rodbell, M. (1977) J. Biol. Chem. 252, 7964--7966). The degree of inhibition by Gpp(NH)p did not depend on the concentration of manganese nor on the addition of ethylene glycol bis(beta-aminoethyl ether)-N, N, N', N'-tetraacetic acid.

Adenylyl Cyclases↗
PubMed1980

Multiplicity of phosphate acceptor proteins for muscle glycogen phosphorylase kinase.

Although muscle glycogen phosphorylase kinase reacts preferentially with an inactive form of phosphorylase, the enzyme is able to phosphorylate in vitro multiple species of unidentified endogenous proteins in mammalian tissues such as liver. The reactions absolutely require Ca2+. Phosphate acceptor proteins are most abundant in the soluble and microsomal fractions. Sodium lauryl sulfate-slab gel electrophoresis analysis has revealed that the spectrum of phosphate acceptor proteins entirely differs from that for cyclic AMP-dependent protein kinase, although the biological significance of these reactions is unclear. Nevertheless, it is suggested that the enzyme is potentially multifunctional and plays roles in controlling some of the Ca2+-dependent processes. In contrast, myosin light chain kinase which is another species of calmodulin-dependent protein kinase seems to be strictly specific for this particular protein, and does not utilize any other endogenous protein so far tested.

Animals↗
PubMed1980

Analysis of the vasomotor waves observed during cardiopulmonary bypass.

From the data of the vasomotor waves (VMW) previously reported, we attempted to retrieve information of the gain and the dead-time of the feedback circuit involved. A mathematical analysis revealed a certain relationship between the gain and the dead-time for the VMW to occur in three models. Combining our result with the data of animal experiments obtained by other researchers, we could exclude one of three models, thereby setting the area of existence of gain-delay value. When we apply a value of 3.4 sec for dead-time, as extrapolated from the animal data, the static gain of the system is between 2.2 and 4.0. Contrary to those observed in animal experiments and to our own original speculation, the VMW in man during cardiopulmonary bypass is likely caused via baroreceptor (carotid sinus) reflex rather than through cerebral ischemic response.

Cardiopulmonary Bypass↗
PubMed1979

A hepatic soluble cyclic nucleotide-independent protein kinase. Stimulation by basic polypeptides.

Enzymatic phosphorylation of cytoplasmic proteins by a cyclic nucleotide-independent protein kinase (casein kinase of a classical type) in rat liver is stimulated greatly, sometimes more than 10-fold, by polycations, particularly by basic polypeptides such as polylysine, histone, and protamine. These basic polypeptides themselves do not serve as phosphate acceptors but act as stimulators for the reaction by interacting with cytoplasmic proteins rather than with enzyme. The stimulatory effect varies with substrates employed; with casein and phosvitin the stimulation does not exceed 2- to 3-fold. The cytoplasmic endogenous phosphate acceptor proteins measurable in the presence of basic polypeptides are abundant for this species of protein kinase.

Animals↗
PubMed1979

Regulatory and functional compartment of three multifunctional protein kinase systems.

Cyclic AMP-dependent protein kinase has been well established to be composed of catalytic and regulatory subunits, and cyclic AMP acts to dissociate these subunits to exhibit full enzymatic activity. In contrast, cyclic GMP-dependent protein kinase does not possess such a subunit structure and is activated by cyclic GMP simply in an allosteric manner. In addition to cyclic AMP-dependent and cyclic GMP-dependent protein kinases, another species of multifunctional protein kinase has been found in many mammalian tissues. This protein kinase is entirely independent of cyclic nucleotides and activated by lower concentrations of Ca2+ in the presence of a membrane-associated factor. This factor has been identified as phospholipids; in fact, phosphatidylinositol and phosphatidylserine are active in this role, whereas lecithin and sphingomyelin are unable to activate the enzyme. Thus, the three species of protein kinases mentioned above are activated in different manners. Nevertheless, these enzymes show very similar substrate specificities and phosphorylate the same specific seryl residues of histone fractions. In addition, all enzymes have abilities to activate and inactivate muscle phosphorylase kinase and glycogen synthetase, respectively, although the relative rates of reactions towards various substrates are markedly different. The Ca2+-dependent protein kinase seems to be associated with membranous components, whereas cyclic GMP-dependent protein kinase appears to be related to certain subcellular organella such as nucleus. Suggestive evidence is available implying that the cyclic AMP-, cyclic GMP- and Ca2+-activated three sets of protein kinase systems may play each specific physiological roles presumably owing to their own subcellular compartments.

Calcium↗
PubMed1979

Regional distribution of amino acids in Friedreich's ataxia brains.

The distribution of amino acids in two Friedreich's ataxia brains is compared to 4 control brains. Glutamate and GABA were decreased in the cerebellar hemispheres and/or in the vermis. Taurine concentrations were uniformly elevated throughout the areas studied. Taurine/glutamate and taurine/GABA ratios were consistently elevated in Friedreich's ataxia brains, whereas glutamate/glutamine ratios were consistently decreased (with normal glutamine concentrations).

Amino Acids↗