Search PubMed⌕ Search

Biomedical subjects

T Kawata

Publications and source records attributed to T Kawata.

At least 235 records · Page 13Linked to original sources
PubMed1987

The site of action of nitrendipine in the rat kidney.

Ample evidence suggests that Ca2+ antagonists like nitrendipine are capable of inducing mild diuresis and natriuresis in states predisposing to natriuresis, although there is disagreement on common possible sites or mechanisms of action. To clarify this situation, clearance, micropuncture, and microperfusion studies were undertaken on rats to establish whether nitrendipine inhibits sodium and fluid reabsorption in strict hydropenia, and if so, in which nephron segments this occurs. The clearance studies failed to show any specific effect on glomerular filtration rate, urine flow, or sodium excretion; mean arterial blood pressure was, however, dose-dependently depressed. Single nephron filtration rate, measured in the distal tubule, was also not altered, but fractional salt and water reabsorption up to that site were modestly reduced. Since microperfusion studies failed to show any inhibition of thick ascending limb transport, this implies a proximal inhibitory action, a conclusion confirmed by proximal microperfusion studies. Thus, in strict hydropenia, nitrendipine inhibits proximal salt and water reabsorption, but the increased distal load is completely compensated by distal tubular and collecting duct mechanisms such that urinary electrolyte excretion is unaltered.

Animals↗
PubMed1986

Properties of Plasma Membrane Isolated from Chilling-Sensitive Etiolated Seedlings of Vigna radiata L.

Plasma membrane was isolated in a uniform population and with a high purity from chilling-sensitive etiolated young seedlings of Vigna radiata (mung bean) utilizing an aqueous two polymer phase separation system and subsequent sucrose density gradient. The isolated plasma membrane was associated with vanadate-sensitive and KNO(3)-insensitive ATPase. The ATPase has high specificities both for substrate and Mg(2+) ion with optimum pH at 6.5. It was slightly stimulated by monovalent anions, especially Cl(-). Proton ionophores such as gramicidin D and carbonyl cyanide p-trifluoromethoxyphenylhydrazone did not stimulate the enzyme activity. The ATPase is apparently latent and highly stimulated by the addition of detergents such as Triton X-100. A maximum stimulation was achieved by the addition of 0.02% Triton X-100. After treatment with proteinase K in an isotonic buffer solution, the enzyme activity was less affected, whereas the peptides were specifically digested. Based on these facts, the isolated plasma membrane vesicles appear to be tightly sealed and in a right-side-out orientation. The plasma membrane ATPase had two inflection points at higher (18.9 degrees C) and lower (6.7 degrees C) temperatures on the Arrhenius plots of the activity. The lower inflection temperature apparently coincided with that of the anisotropy parameter of embedded 1,6-diphenyl-1,3,5-hexatriene, indicating that the membrane bound ATPase activity was affected by a phase transition of membrane lipids and/or temperature-dependent conformational changes in the enzyme molecules per se. Considering the fact that the plant material used here is highly sensitive to chilling temperatures and injured severely by exposure to temperatures below 5 degrees C for a relatively short period, the thermotropic properties of membrane molecules are considered to be involved in the mechanism of chilling injury.

Journal Article↗
PubMed1986

Isolation and Characterization of Tonoplast from Chilling-Sensitive Etiolated Seedlings of Vigna radiata L.

Tonoplasts were isolated in a high purity from etiolated young seedlings of Vigna radiata L. (mung bean) utilizing a sucrose density gradient system. The excised hypocotyls were homogenized in a sorbitol-buffer system and the 3,600 to 156,000g pellets obtained after the differential centrifugations were suspended in a sorbitol medium and loaded on a linear sucrose density gradient. After centrifugation at 89,000g for 2 hours, tonoplasts were banded at the sample load/sucrose interface. Assessed by electron microscopy and marker enzymes, the purity and the quantity were found to be sufficient for biochemical and biophysical analyses. The tonoplasts were associated with NO(3) (-)-sensitive and vana-date-insensitive ATPase. The tonoplast ATPase was stimulated by proton ionophores such as carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone and gramicidin D, suggesting a proton-pumping enzyme. In the presence of ATP and Mg(2+), a proton gradient was formed in the isolated tonoplast vesicles as assessed by fluorescence quenching of quinacrine. The tonoplasts contained several kinds of mannosylated or glycosylated glycoproteins and a major protein (65 kilodaltons) which was unique to the membranes.

Journal Article↗
PubMed1986

Composition of major outer membrane proteins of Vibrio vulnificus isolates: effect of different growth media and iron deficiency.

The outer membrane proteins of Vibrio vulnificus including isolates from humans, seawater and an asari clam were examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. A major outer membrane protein with an apparent molecular weight of 48,000 (48K protein) was common to all the strains grown in 3% NaCl-nutrient broth; however this 48K protein was not produced in any of the strains grown in chemically defined medium. Other major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 varied in number, relative amount and molecular weight depending on the strain. One to three new outer membrane proteins with molecular weights ranging from 74,000 to 85,000 were produced in the cells grown in iron-deficient medium. The 48K protein and one or two major proteins with molecular weights ranging from 35,000 to 37,000 in the cells grown in 3% NaCl-nutrient broth were not solubilized by 2% SDS at 60 C for 30 min and were resistant to trypsin, indicating that they are porins. On the other hand, in cells grown in chemically defined medium, one or two major outer membrane proteins with molecular weights ranging from 33,000 to 40,000 might be porins.

Bacterial Outer Membrane Proteins↗
PubMed1986

Isolation, and structural and chemical characterization of outer sheath carrying a polygonal array from Treponema phagedenis biotype Reiter.

An outer sheath was isolated from Treponema phagedenis biotype Reiter by our previously developed method (Masuda, K., and Kawata, T. 1982. J. Bacteriol. 150: 1405-1413). The isolated outer sheath was observed as a triple-layered, closed vesicle carrying a polygonal array by electron microscopy. The outer sheath was mainly composed of protein (41.0%), phospholipid (38.7%), and carbohydrate (11.0%). Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the isolated outer sheath in the presence of 2-mercaptoethanol (EtSH) gave one major protein band with an apparent molecular weight of about 69,000 and several minor protein bands. On the other hand, in the absence of EtSH, the major protein band disappeared but two new protein bands at positions of molecular weights of about 65,000 and 72,000 appeared. The SDS-PAGE profiles of the minor protein bands did not change with or without EtSH. Sodium deoxycholate (DOC)-solubilized materials from the isolated outer sheath were reassembled into thin membranous sheets carrying a roughly polygonal array upon removal of DOC by dialysis against Tris-HCl buffer in the absence of Mg2+.

Bacterial Proteins↗
PubMed1985

Solubilization and partial properties of receptor substance for bacteriophage alpha 2 induced from Clostridium botulinum type A 190L.

Bacteriophage alpha 2, one of the two inducible phages from Clostridium botulinum type A 190L, had a latent period of 55 min and an average burst size of 75 in C. botulinum type A Hall used as the host bacterium. The phage particles were adsorbed on the cell walls extracted with hot trichloroacetic acid (TCA-walls). The receptor substance for the phage was solubilized from the TCA-walls with Achromopeptidase and fractionated by gel filtration on Sephadex G-150. The fraction having the highest level of receptor activity for the phage contained large amounts of muramic acid and glucosamine. Both authentic muramic acid and glucosamine significantly inactivated the phage, whereas glucose, galactose, L-and D-alanine, diaminopimeric acid, or D-glutamic acid did not exhibit similar activity. There results strongly suggest that the receptor site for phage alpha 2 is closely associated with glycan moieties of the cell wall peptidoglycan.

Bacteriophages↗
PubMed1985

[Epidemiological studies on pancreatic cancer].

An epidemiological study on pancreatic cancer was performed, using for evaluation reports from the Ministry of Public Welfare and the National Pancreatic Cancer Registration Committee and cases experienced at the First Department of Surgery in Kobe University Hospital. The incidence of pancreatic cancer was found to have increased over the lost few decades. Aged subjects with family histories of malignant diseases and cases having past histories of chronic pancreatitis were affiliated with the high-risk group for this disease. Cigarette smoking and beverage consumption were also shown to be increased risk factors for pancreatic cancer. Poor results obtainable with the types of treatment presently available for pancreatic cancer indicated the clinical significance of applying screening methods for subjects in the high-risk group.

Adult↗
PubMed1985

Reassembly of a regularly arranged protein in the cell wall of Lactobacillus buchneri and its reattachment to cell walls: chemical modification studies.

Regularly arranged protein (RA protein) isolated from the cell wall of Lactobacillus buchneri was chemically modified by amidination, acetylation, succinylation, and amidation. The modified RA proteins were examined for their ability to reassemble into a regular array and to reattach to the cell walls from which the regular array had been detached. Only amidinated RA protein could be either reassembled into a regular array or reattached to the cell walls; RA proteins modified by the other methods lost the ability for both reassembly and reattachment. The unmodified RA protein could be reattached to periodate-oxidized cell walls, but not to methylated ones. These results suggest that the positive charge of the amino group as well as the negative charge of the carboxyl group of RA protein plays an important role(s) in morphogenesis of the hexagonal array and in its attachment to the underlying cell wall layer. The periodate-insensitive lone hydroxyl groups of the neutral polysaccharide molecule in the cell wall seem to be the receptor sites for RA protein in the attachment to the cell wall.

Bacterial Proteins↗