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Biomedical subjects

M Kikuchi

Publications and source records attributed to M Kikuchi.

At least 1,117 records · Page 62Linked to original sources
PubMed1978

Uptake, distribution, and elimination of sodium linear alkylbenzene sulfonate and sodium alkyl sulfate in carp.

Uptake, distribution, and elimination of labeled surfactants, 35S-labeled sodium laurylbenzenesulfonate (35S-C12-LAS) and 35S-labeled sodium lauryl sulfate (35S-C12-AS), were investigated in carp exposed to a low concentration level of the respective solutions found in river water in Japan by whole-body autoradiography and liquid scintillation counting. Whole-body autoradiograms showed that the fish absorbed 35S-C12-LAS and 35S-C12-AS from the solutions principally through gills and that the surfactants absorbed were rapidly distributed throughout the body tissues and organs. High concentrations were found in gills, blood, hepatopancreas, kidney, and gall bladder. The elimination in the fish that were kept in clean fresh water after exposure were relatively rapid in most tissues and organs except for gall bladder. These results suggest that the surfactants absorbed in fish may have an adverse effect on many tissues and organs of fish. What influenced the distribution profile and concentration factors of the surfactants in tissues and organs of carp were the exposure time and the molecular structure of the surfactants.

Alkanesulfonates↗
PubMed1978

Malignant melanoma of the gallbladder.

A rare case of primary malignant melanoma of the gallbladder was studied with the electron microscope. Two interesting patterns were observed: numerous melanophages were present in the tumor tissue and wrapped compound melanosomes were found in nonneoplastic mucosal epithelium. The infiltration of melanophages was considered to be a reaction to degenerated tumor cells. Concerning the mechanism of melanosome transport into the epithelial cells, a cooperative action between epithelial and melanoma cells seemed to be the most important factor.

Aged↗
PubMed1978

Promotion of monolayer formation in cultured whole pancreatic islets by 3-isobutyl-1-methylxanthine.

Normal adult rat islets usually remained intact and encapsulated, even after many days in culture. In contrast, islets cultured in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.1 mM) attached more readily to the surface of plastic culture dishes and almost uniformly formed monolayers of endocrine cells. The mechanism of this effect is not known but presumably involves increases in cellular cyclic AMP content. Fibroblast growth did not appear to be stimulated by the inhibitor. These adult pancreatic endocrine monolayer cultures can be produced readily and provide useful preparations for further morphological and biochemical studies of factors affecting the differentiation, growth, and regenerative capacity of islet cells.

Animals↗
PubMed1978

Inhibition of platelet function by sulbenicillin and its metabolite.

The effect of sulbenicillin and its major metabolite, alpha-sulfobenzylpenicilloic acid, on platelet function was investigated. Sulbenicillin caused inhibition of platelet aggregation and release reaction in the same manner as carbenicillin. alpha-Sulfobenzylpenicilloic acid was found to cause much stronger inhibition of platelet function. The results indicate that the strong inhibitory action of alpha-sulfobenzylpenicilloic acid may also take part in impaired platelet functions following administration of sulbenicillin to humans.

Blood Platelets↗
PubMed1978

Characteristics of bacteriophages for Micromonospora purpurea.

Chemical and physical stabilities of bacteriophages øUW 21 and øUW 51 infecting Micromonospora purpurea ATCC 15835 were examined. Both phages were stable over the pH range of 5 to 8 and to heating at temperatures up to 50 degrees C and especially stable in buffer containing magnesium ion. Exposure to 1 M Ca(NO3)2 inactivated both phages, and phage øUW 51 was also susceptible to 1 M CaCl2, 0.1 M tris(hydroxymethyl)aminomethane, and 0.3% H2O2. Phage plating efficiency was highest on the cultures at logarithmic phase and sometimes much influenced by host growth. Phage øUW 51 has a latent period of 2 h at 34 degrees C and a burst size between 35 and 40. The latent period for phage øUW 21 is about 12 h, and the burst size is smaller than 30.

Bacteriophages↗
PubMed1978

The roles of intracellular and extracellular Ca++ in glucose-stimulated biphasic insulin release by rat islets.

Verapamil, an agent known rapidly to block calcium uptake into islets of Langerhans, has been used to study the roles of intra- and extracellular calcium in the two phases of glucose-induced insulin release. Rates of calcium uptake and insulin release during the first phase were measured simultaneously over 5 min in rat islets after maintenance in tissue culture for 2 days. Rates of (45)Ca(++) efflux and insulin release during the first and second phases were also measured simultaneously under perifusion conditions. For this, islets were loaded with (45)Ca(++) during the entire maintenance period to complete isotopic equilibrium. Under static incubation conditions 5 muM Verapamil had no effect upon Ca(++) uptake or insulin release in the presence of 2.8 mM glucose. By contrast, glucose-stimulated calcium influx was totally abolished without there being any significant effect upon first phase insulin release. Thus first phase insulin release is independent of increased uptake of extracellular calcium. The lack of effect of 5 muM Verapamil blockade on first phase insulin release was confirmed, under perifusion conditions, and was in marked contrast to the observed 55% inhibition of second phase release. (45)Ca(++) efflux was inhibited during both phases of the insulin release response. The results show that increased calcium uptake in response to glucose is not involved in the mechanism of first phase insulin release but is required for the full development and maintenance of the second phase release. It seems possible that intracellular calcium is the major regulatory control for first phase insulin release and that intracellular calcium and increased uptake of extracellular calcium contribute almost equally to the second phase of glucose-induced release.

Animals↗
PubMed1978

Studies on the dual effects of glucose on 45Ca++ efflux from isolated rat islets.

45Ca++ efflux studies were performed on rat islets of Langerhans which were loaded to isotopic equilibrium during 48 h in tissue cultures. 45Ca++ loading was 50% complete at 1 h, 80% at 4 h, and reached, at equilibrium, a content equal to 10-11 pmol/islet. The islets responded to glucose stimulation with a rapid and markedly biphase insulin release. Under normal conditions, glucose stimulated 45Ca++ efflux with an initial surge (simultaneous with the first peak of insulin release), which declined rapidly to 50% of the peak value and then slowly declined for the remainder of the glucose stimulation. Special conditions were required to uncover an early inhibition of 45Ca++ efflux; these were the lowering of the temperature of the perifusate from 37 C to 30 C or below, or reduction of the medium Ca++ concentration to 0.1 mM or less. Under zero calcium conditions the glucose inhibition of 45Ca++ efflux can be rigorously interpreted as an inhibition of calcium efflux. The studies at low temperature or low Ca++ concentrations revealed two effects of glucose on 45Ca++ efflux: an initial inhibition followed by a stimulation, the inhibitory effect was obscured by the rapidity of onset of the stimulatory effect under normal conditions. At low temperature it was also possible to inhibit glucose-stimulated insulin release, although the stimulated 45Ca++ efflux remained unchanged. At 30 C or in experiments with 0.3 mM Ca++, glucose-stimulated insulin release preceded the stimulation of 45Ca++ efflux. It therefore, is, concluded that the stimulated 45Ca++ efflux is a consequence, rather than a determinant, of stimulus-secretion coupling. The stimulated efflux is dependent on the presence of Ca++ in the medium and is independent of emiocytosis. This latter finding excludes the secretory granules as a significant source of glucose-stimulated 45Ca++ extrusion.

Animals↗