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Biomedical subjects

K Hotta

Publications and source records attributed to K Hotta.

At least 325 records · Page 18Linked to original sources
PubMed1980

Enzymatic hydrolysis of disaccharide unit of collagen. Isolation of 2-O-alpha-D-glucopyranosyl-O-beta-D-galactopyranosyl-hydroxylysine glucohydrolase from rat spleens.

The hydroxylsine-linked disaccharide unit, 2-O-alpha-D-glucopyranosyl-O-beta-D-galactopyranosyl-hydroxylysine (Glc-Gal-Hyl), prepared from collagens, was hydrolyzed by a glucohydrolase present in rat spleens and lungs. This disaccharide unit was scarcely hydrolyzed by homogenates of intestines, livers, and kidneys, which had a high alpha-D-glucosidase activity for neutral glucosides. The Glc-Gal-Hyl glucohydrolase was purified from rat spleens by affinity chromatography and gel filtration to the extent that sodium dodecyl sulfate/polyacrylamide gel electrophoresis gave a single band stained by Coomassie blue G-250. This purified glucohydrolase had a pH optimum around 5.8, and the Michaelis constant was 5.9 mM when Glc-Gal-Hyl was used as a substrate. This enzyme did not hydrolyze neutral glucosides. It is concluded that this Glc-Gal-Hyl glucohydrolase is responsible for catabolism of the hydroxylsine-linked disaccharide unit derived from collagens in mammals.

Animals↗
PubMed1980

Correlation of quantitative changes of gastric mucosal glycoproteins with aspirin-induced gastric damage in rats.

Quantitative changes of gastric mucosal glycoproteins with the gastric damage induced by acetylsalicylic acid (aspirin) in rat have been studied. Gastric injury was easily observed macroscopically within one hour after the oral administration of aspirin. The most striking changes occurred at five hours, and the injury was overcome within nine hours after dosing. The glycoproteins extracted from rat stomack with Tris buffer containing Triton X-100 were fractionated on Bio-Gel A-1.5 m column chromatography and divided into three fractions. The first peak, corresponding to gastric mucus macromolecular neutral and acidic glycoproteins with or without sulphate (Fr.I), was diminished after aspirin administration. A considerable alteration of Fr.I (49% of control) appeared at three hours, and a gradual return to the control value was observed subsequently. The changes in the amount of the glycoproteins were detected before the macroscopical changes of the mucosa. These results suggest that gastric ulceration induced by aspirin may be caused by a deficiency of gastric mucus macromolecular glycoproteins of gastric mucus.

Animals↗
PubMed1980

Identification of the sialic acids from the egg jelly coat of the sea urchin Pseudocentrotus depressus (Okayama).

The jelly coat substance of the sea urchin eggs of Pseudocentrotus depressus (Okayama) was found to contain 0.35% sialic acids. After isolation of the sialic acids from the purified sulfated sialoglycoprotein containing 11% of sialic acids, analysis by colorimetry, thin-layer chromatography and gas-liquid chromatography/mass spectrometry demonstrated the nature of the sialic acids to be N-glycolylneuraminic acid and 9-O-acetyl-N-glycoloylneuraminic acid. The molar ratio between both sialic acids was found to be 1 : 1. Since it is known that O-acyl groups are partially released during the hydrolysis and isolation procedure, it can be assumed that in the native glycoprotein the percentage of O-acetylation is much higher than 50%. The sugar and sulfate composition of the glycoprotein is also described.

Animals↗
PubMed1980

Study on tubular transient current and mechanical activation in skeletal muscle of frog.

The relation between membrane current and mechanical activity during excitation of frog muscle fibers was studied using two-microelectrode voltage clamp technique. The current flow upon excitation of membrane consisted of transient initial inward and subsequent outwards currents which were carried by Na+ influx and K+ efflux respectively. Blocking of the outward K+ current by 3,4-diaminopyridine resulted in appearance of a late inward current associated with marked potentiation of twitch tension. Detubulation of the fiber by treatment with hypertonic glycerol suppressed the outward K+ current as well as the late inward current and abolished the contractile force. Dantrolene also gave similar effects on membrane currents and reduced twitch tension markedly. These results suggest that the late inward current through the T-system and not the outward K+ current may be the first step to lead the muscle cell to mechanical activation.

Animals↗
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. I. The use of plasmid profiles in screening antibiotic-producing streptomycetes.

Plasmid profiles were used to screen streptomycetes for production of new antibiotics. Among about 100 strains isolated from sea muds, an isolate designated SS-939 was revealed to harbor several plasmids of different sizes, and to produce istamycins, new aminoglycoside antibiotics. Based on the characteristics of the strain, a new Streptomyces species is proposed: S. tenjimariensis.

Aminoglycosides↗
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. II. Possible involvement of plasmid in istamycin production.

Acriflavine treatment of an istamycin-producing Streptomyces tenjimariensis strain designated SS-939 resulted in a high frequency of isolates with reduced istamycin production. Some of these were shown to have lost a particular plasmid present in the parent strain. Istamycin production by these isolates was largely restored by the addition of 2-deoxystreptamine (DOS) to the medium whereas the effect of DOS was small in the strain SS-939. Sodium palmitate also stimulated production, especially when added together with DOS. These stimulative effects by DOS and palmitate, however, were not exhibited in the presence of glucose (1.0%).

Acridines↗
PubMed1980

Studies on new aminoglycoside antibiotics, istamycins, from an actinomycete isolated from a marine environment. III. Nutritional effects on istamycin production and additional chemical and biological properties of istamycins.

Streptomyces tenjimariensis SS-939 produced istamycins in a medium containing starch as the carbon source and soy bean meal as the nitrogen source. Istamycin production decreased substantially when starch was substituted with mono- or di- saccharides such as glucose, glycerol and maltose. A marked decrease of istamycin production was also observed when a rapidly used nitrogen source such as yeast extract, peptone or casamino acid was employed instead of soy bean meal. Addition of palmitate at a concentration of 0.2% doubled istamycin production. Istamycins A and B were found to be as active as fortimicin A and sporaricin A against Gram-positive and Gram-negative bacteria including aminoglycoside-resistant strains.

Aminoglycosides↗
PubMed1979

Characterization of peptic inhibitory activity associated with sulfated glycoprotein isolated from gastric mucosa.

Sulfated glycoproteins were extracted and purified from porcine stomach mucous scraping. Four sulfated glycoprotein fractions were separated and subsequently purified. These compounds always accompanied the apparent peptic inhibitory activity and consisted of 15-18% (w/w) protein. The carbohydrate portions contained an equimolar ratio of galactose and hexosamine (mainly glucosamine), together with lesser amounts of fucose and sialic acid. The sulfate content of the above fractions was 2-9% (w/w) of the total sulfated glycoprotein. The mode of inhibition of the sulfated glycoproteins to peptic activity was investigated and suggested that there was binding of the sulfated glycoproteins to the substrate of pepsin, making the substrate resistant to peptic activity. The sulfated glycoproteins neither bound pepsin at pH 1.8 nor inhibited the hydrolysis of a synthetic dipeptide substrate of pepsin. Desulfation of the sulfated glycoproteins resulted in the loss of both the inhibitory activity and the precipitate formation. The precipitation curve for sulfated glycoprotein and porcine serum albumin showed that both bound in varying proportions and suggests that both components are multivalent in this precipitate formation.

Amino Acids↗
PubMed1978

Transient effect of intracellular dantrolene on E--C coupling in skeletal muscle.

The effect of dantrolene-Na (DAN) on electrical and mechanical responses was investigated to single fibers of frog semitendinosus. Twitch tension was potentiated over 2--4 min by intracellular application of DAN and was rapidly decreased thereafter. Extracellular DAN depressed the tension with all dosages used. Although DAN had no effect on membrane potential, it exerted a biphasic action on membrane excitability. From these results, a mechanism is postulated for the release of trigger Ca2+ from T-tubules.

Action Potentials↗