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Biomedical subjects

M Koga

Publications and source records attributed to M Koga.

At least 505 records · Page 28Linked to original sources
PubMed1979

Cytotoxic, cell agglutinating, and syncytium forming effect of purified lectins from Ricinus communis on cultured cells.

The toxicity of lectins from castor bean (Ricinus communis L.), ricin-D, ricin-E, and castor bean hemagglutinin, was investigated on five cultured cell lines. The differential effect of their constituent polypeptide chains was also investigated using these cell lines. Ricin-D, ricin-E, and castor bean hemagglutinin (CBH) possessed cytoagglutinating activity and cytotoxic activity to all five cell lines. These lectins showed the strongest toxicity to L5178Y cells, which are leukemic cells. The toxic activity of ricin-D was stronger than that of CBH in all cell lines. The constituent polypebtide chains of ricin-D and CBH were separated by DEAE-cellulose chromatography and designated as isoleucine chain and alanine chain denoted by their N-terminal amino acids. Only alanine chain of ricin-D was toxic to cells grown in vitro, whereas isoleucine chain of ricin-D and alanine chain of CBH were not toxic to the cells. Moreover, it was found that both lectins caused syncytium formation in NIH3T3 cells infected with Moloney leukemia virus and this cell fusion activity was shown to be exclusively associated with the alanine chain. Cytotoxic, cell agglutinating, and syncytium forming effect of the lectins is due to binding of the alanine chain of ricin-D to galactose-like residues of the membrane constituents of these cells.

Agglutination↗
PubMed1978

Zinc-binding protein in the livers of neonatal, normal and partially hepatectomized rats.

In the livers of rats after partial hepatectomy the zinc concentration began to increase soon after the operation, reached a maximum value at 14h, and decreased to the original value by 25h after the operation. In contrast, the plasma zinc concentration continued to decrease during the first 10h after the operation and remained depressed for at least 28h. The plasma and hepatic zinc concentrations were relatively unaffected by sham-operation. Synchronous with the increase in the hepatic zinc concentration after the partial hepatectomy, there was an appearance of zinc-binding protein (Zn-binding protein) in the liver cytosol. Studies with small doses of actinomycin D and cycloheximide suggest that both RNA and protein syntheses are necessary for the induction of Zn-binding protein after partial hepatectomy. A high content of the Zn-binding protein was found in neonatal rat liver. The Zn-binding protein, however, was undetectable 40 days after birth. The Zn-binding protein was also found in the adult rat liver when stimulated to proliferate after the administration of isoprenaline followed by glucagon. These findings indicate a close linkage between the appearance of Zn-binding protein in the liver cytosol and the regulation of DNA synthesis.

Animals↗
PubMed1978

Field desorption mass spectrometric analysis of organic compound residues in the environment. I--Organochlorine insecticides.

Field desorption mass spectrometry is applied to the positive identification of organochlorine insecticides and their related compounds residing in field soil environment. Additionally, standard field desorption mass spectra of these compounds are presented. Soil samples were collected in lettuce and spinach fields, and insecticides were extracted, cleaned up, and separated with thin-layer chromatography. Residue levels were measured by injecting the extract into a gas chromatography equipped with an electron capture detector. Residues of p,p'-DDT and dieldrin in field soil samples were clearly identified by field desorption mass spectrometry using the emitter dipping method. Moreover, mixed residues of these insecticides were simultaneously confirmed. However, residues of insecticides and their related compounds other than p,p'-DDT and dieldrin could not be characterized. All spectra of standard showed prominent [M].+, [M(35Cl(n-1), 37Cl)].+ and [M(35Cl(n-2, 37Cl2)].+ ions, and the [M(35Cl(n-1), 37Cl)].+ ion was the base peak in all spectra obtained.

Chromatography, Gas↗
PubMed1978

Chronic alcoholism: report of an autopsy case and comparison with pseudoulegyric type of hepatocerebral degeneration.

An autopsy case diagnosed as chronic alcoholism was reported. He clinically showed progressive neurological illness. His CNS lesions were composed of disseminated necrotic foci in the cerebral cortices with many Alzheimer type II astrocytes, pachymeningitis hemorrhagica interna, and lesions similar to pellagra and Wernicke encephalopathy. Some clinical and pathological analogous features between chronic alcoholism and pseudoulegyric type of hepatocerebral degeneration were discussed.

Adult↗
PubMed1978

Cholesterol from serum and cholesterol-phospholipid dispersions by isolated rat hepatocytes in vitro.

The rate of uptake of cholesterol by isolated rat hepatocytes from incubation medium containing rat serum was low and did not increase by the prolongation of incubation time up to 2 hr at 4 degree. However, the hepatocytes took up cholesterol very actively at 37.5 degree from serum as well as from a cholesterol-phospholipid dispersion. The cholesterol uptake by the cells from liposomes increased linearly with the increase of the cholesterol concentration of liposomes, but that from serum reached the maximum at about 1.5 mu mol/ml cholesterol and remained at a plateau level at higher concentrations. Cholesterol was transfered from every class of serum lipoprotein, although the uptake ratio was the highest from the LDL fraction. As the lipoprotein concentration was increased, the uptake ratio decreased in the same way as that observed in the incubation with whole serum. The concentration of labeled ester cholesterol in the medium decreased more rapidly than free cholesterol during incubation. Cholesterol in the hepatocytes, however, was found mainly as the free form, suggesting that ester cholesterol taken up by the cells was rapidly hydrolyzed. Cholesterol accumulation was not observed in hepatocytes incubated in medium containing serum, but their cholesterol content was increased after the incubation in medium with liposomes of high cholesterol concentration. Therefore the uptake of cholesterol by hepatocytes from serum lipoproteins is probably carried out by a process different from that of uptake from liposomes which is considered to be a physicochemical phenomenon.

Animals↗