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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 1,261 records · Page 70Linked to original sources
PubMed1980

Role of glucagon and somatostatin in insulin release.

The role of endogenous glucagon and somatostatin in insulin release was studied. Islets isolated from adult rats were incubated for 60 min in 3.3, 8,3 and 16.7 mM glucose with anti-glucagon antiserum (AGA) or anti-somatostatin antiserum (ASA) which was produced in rabbits. For the control experiments the antiserum was replaced by normal rabbit serum (NRS). Insulin release from islets treated with AGA was suppressed in 3.3 and 8.3 mM glucose as compared to islets treated with NRS, while insulin release was not affected in 16.7 mM glucose. On the other hand, insulin release from islets treated with ASA was enhanced in 3.3 and 8.3 mM glucose as compared to that from islets treated with NRS, whereas in 16.7 mM glucose it was not different from the control. These observations indicate that endogenous glucagon and somatostatin play a physiological role in the regulation of insulin release, but their regulation of insulin release is deranged at non-physiologically high glucose concentrations.

Animals↗
PubMed1980

Drug information services for consumers and health professionals.

Provision of drug information services to both health professionals and consumers is described. The Rocky Mountain Drug Consultation Center (RMDCC) has been available to health professionals at Denver General Hospital since 1977. In April 1979, the RMDCC began promotion of combined health-professional- and consumer-oriented services. The service operates 8 a.m. to 6 p.m., Monday through Friday, with 24-hour on-call service. It is staffed by pharmacists who devote 70 man-hours per week to it. Training is primarily on the job. Most of the $80,500 budget is funded through a public health grant from the State of Colorado. a nine-member physician advisory board periodically reviews quality of responses. During a one-year period (April 1979-March 1980), 2264 calls were received from consumers and 1762 calls from health professionals--an increase of 197% over the previous year. Approximately 90% of consumer calls were not considered serious problems or were informational requests; 10% were considered potentially serious or serious drug-related problems. Less than 1% of consumers' questions required the use of anything more than basic drug information references. Of 76 follow-up calls made to consumers for serious or potentially serious problems, 73 were successfully recontacted, and 70 said they either followed RMDCC's recommendations or contacted their physician. The authors believe that combined consumer-oriented and health-professional-oriented drug information services help prevent misuse of medications by consumers.

Colorado↗
PubMed1979

Effects of monovalent cations on AMP nucleosidase from Azotobacter vinelandii.

The effect of monovalent cations on the purified AMP nucleosidase (AMP phosphoribohydrolase, EC 3.2.2.4) from Azotobacter vinelandii was investigated. All the monovalent cations were activators of the enzyme: Rb+ and Cs+ were the most effective, followed by K+, Na+, NH4+ and Li+ in that order. The apparent Ka for MgATP and nH values (Hill's interaction coefficient) decreased from 0.9 to 0.1 mM, and from 4 to 1, respectively, with the increase in K+ concentration, suggesting that the cation effects are on MgATP binding rather than catalysis. Gel filtration studies have revealed that the enzyme forms a non-dissociable enzyme species with a Stokes radius of 6.0--6.2 nm in the presence of saturating concentrations of monovalent cations, which can be distinguished from the 5.5-nm enzyme species showing temperature-dependent dissociation of the molecule in sulfate or phosphate. These results suggest that these ligands affect the association of the subunits through changes in the environment of the hydrophobic side chains of the enzyme molecules.

Adenosine Monophosphate↗
PubMed1979

AMP deaminase from baker's yeast. Purification and some regulatory properties.

AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) was found in extract of baker's yeast (Saccharomyces cerevisiae), and was purified to electrophoretic homogeneity using phosphocellulose adsorption chromatography and affinity elution by ATP. The enzyme shows cooperative binding of AMP (Hill coefficient, nH, 1.7) with an s0.5 value of 2.6 mM in the absence or presence of alkali metals. ATP acts as a positive effector, lowering nH to 1.0 and s0.5 to 0.02 mM. P1 inhibits the enzyme in an allosteric manner: s0.5 and nH values increase with increase in Pi concentration. In the physiological range of adenylate energy charge in yeast cells (0.5 to 0.9), the AMP deaminase activity increases sharply with decreasing energy charge, and the decrease in the size of adenylate pool causes a marked decrease in the rate of the deaminase reaction. AMP deaminase may act as a part of the system that protects against wide excursions of energy charge and adenylate pool size in yeast cells. These suggestions, based on the properties of the enzyme observed in vitro, are consistent with the results of experiments on baker's yeast in vivo reported by other workers.

AMP Deaminase↗