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Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 613 records · Page 34Linked to original sources
PubMed1981

Protein synthesis in the isolated forespores from sporulating cells of Bacillus subtilis.

Developing forespores were isolated from Bacillus subtilis at different stages of sporulation and protein synthesis in the forespore compartment was examined. Pulse-labeling experiments indicated that [14C]phenylalanine was continuously incorporated into the sporangium throughout sporulation, and at t5 (early stage V of sporulation) 58% of the radioactivity was located in the forespore compartment. Significantly high incorporation of [14C]phenylalanine was observed when the isolated forespores at t5 were incubated with the corresponding mother-cell cytoplasmic fraction or an amino acid mixture. About 73% of the radioactivity incorporated into the isolated forespore at t5 was found in the cytoplasmic fraction and 26% in the membranous fraction. Analysis by sodium dodecyl sulfate-gel electrophoresis showed that the 14C-labeled cytoplasmic protein had a molecular weight of about 20,000, and that a protein having the same molecular weight was present in the t5 forespore as a slight protein band and also in the mature spore as a clear protein band. Gel electrophoresis also revealed that the 14C-labeled membranous-soluble protein (prepared by solubilization with detergents) had broad peaks with molecular weights of about 74,000, 33,000, 20,000, and 12,000.

Bacillus subtilis↗
PubMed1981

Effect of histamine on the gastric smooth muscles of guinea pig.

The responses to histamine were studied in circular smooth muscles of three different regions of the guinea pig stomach: the fundus, the antrum and the pylorus. Histamine elicited contractions in all three regions. The contractile responses to histamine were completely abolished by mepyramine (10(-3) g/l). These results showed the presence of H1 receptors, which mediate contractile response, in all regions of the stomach. In the presence of mepyramine, histamine caused marked relaxation in the preparations from the fundus contracted by acetylcholine. This relaxation was noticeably suppressed by cimetidine, indicating the existence of H2 receptors in the fundus.

Acetylcholine↗
PubMed1981

Studies on protease from marine bacteria. 1 Isolation of marine Pseudomonas sp 145-2 and purification of protease.

Marine Pseudomonas strain 145-2 having the ability to produce extracellular protease was isolated from Uwa sea water, Ehime prefecture in Japan. This strain grows at 0 degrees - 37 degrees C, but protease production was observed only during 6-10 h cultivation at 20 degrees - 30 degrees C, when casein, as the nitrogen and carbon source in a concentration of 0.5-1.0%, was used. Maximum production of protease by the strain was also observed. Na, K, Ca and Mg ions were needed for growth and production of protease. Two extracellular proteases (proteases I and II) were purified from the culture supernatant by ammonium sulphate fractionation following Sephadex gel chromatography. Protease I had a larger molecular weight than protease II. After purification, proteases I and II were revealed as homogeneous by acrylamide gel electrophoresis and immunoelectrophoresis.

Amino Acids↗
PubMed1980

Changes of the rotavirus concentration in faeces during the course of acute gastroenteritis as determined by the immune adherence hemagglutination test.

Concentrations of rotavirus were studied in serially sampled faecal specimens from 55 patients with acute gastroenteritis, utilizing the immune adherence hemagglutination (IAHA) test. Rotavirus antigen was detected in 45 (82%) out of 55 cases. In the faeces which were positive for rotavirus antigen, the concentrations reached their maximum titer shortly after the onset of the illness and diminished gradually until the 9th day.

Acute Disease↗
PubMed1980

The regional difference in the responses of the guinea pig gastric muscles to gastrin.

The responses to gastrin were studied in the circular muscles of guinea pig stomach. The muscle strips were prepared from the three different regions of the stomach; the pylorus, the antrum and the upper body. The responses to gastrin, which were concentration dependent contractions, appeared only in the preparations from the upper body. The contractile response of the upper body was observed not by the cumulative application of gastrin, but by the one show applications between which interval was 30 minutes. In contrast, any response to gastrin was not obtained in the other two regions. The contractile response to gastrin in the upper body was not affected by any antagonist, mepyramine 10(-6)g/ml, atropine 10(-6)g/ml, cimetidine 3 X 10(-5)g/ml or tetrodotoxin 10(-7)g/ml. In conclusion, it is reasonable that gastrin may act on the circular muscle of the upper body and cause the concentration dependent contraction by its direct effect.

Animals↗
PubMed1980

Studies on the bacterial spore coat. (7) Properties of alkali-soluble components from spore coat of Bacillus megaterium.

Properties of alkali-soluble components from the spore coat of Bacillus megaterium were examined by physicochemical methods. They were composed of acidic polypeptides of various molecular weights with small amounts of phosphorus and sugar. They were allowed to dissociate to unit components by incubation with SDS. The major component was partially purified by gel filtration, and shown to have a mean molecular weight of about 11,000.

Bacillus megaterium↗
PubMed1980

Location of elements in ashed spores of Bacillus megaterium.

The structure of the skeleton of spores of Bacillus megaterium was examined after ashing in a plasma asher and the elemental composition of the ashed whole spores was determined with an analytical electron microscope. All spores were ashed in situ although they shrank by about 15%. Even P and S, in addition to metals, were recovered well from ashed samples. Ash was rich in the core and the coat, and poor in the cortex. Ca, P, S, and Mg were detected in the core and coat of the spore of B. megaterium QM B1551. Ca in the core was markedly decreased by germination or autoclaving. In the spore of B. megaterium ATCC 19213, almost all of the ash was detected in the core and its elemental composition was similar to that of the core of the strain QM B1551 spore. These reuslts suggest strongly that the core is the site of Ca associated with dipicolinic acid.

Bacillus megaterium↗
PubMed1980

Microbial degradation of a macrotetrolide miticide in soil.

Macrotetrolide, a miticide consisting of tetranactin, trinactin, and dinactin, was readily biodegradable and hence did not accumulate in soil. [U-C]macrotetrolide was rapidly degraded via its constituent hydroxycarboxylic acids to carbon dioxide and water. In culture media, however, the mixture was hydrolyzed to homononactic and nonactic acids by three strains of Bacillus sp. and two of Micrococcus sp. The latter strains were able to hydrolyze 500 mug of the antibiotic per ml within a few days and to grow in the presence of 4,000 mug of the antibiotic per ml. However, they were unable to assimilate the constituent acids which accumulated in the culture medium.

Journal Article↗
PubMed1980

An extension of pA principle to the potentiation of drug effects, and its application to the biological assay of some anticholinesterases and cardenolides.

A new scale for the potentiation was introduced and was termed pA1/2. The value can be calculated by using an equation; (Formula: see text), which is similar to that which is used for the calculation of pA2. For the use of the equation, the parallel shift of the dose-response curve and the unchanged maximum response are prerequisites. This experiment showed the validity and the usefulness of calculating the pA1/2 values, in the biological assay. In the assay of anticholinesterases, the potentiating effects of neostigmine or physostigmine on the acetylcholine-induced contraction were examined, by using frog's rectus abdominis. The pA1/2 values obtained in the presence of two different concentrations of anticholinesterases were the same, indicating that pA1/2 is a parameter which is specific to the potentiator. The potentiating effects of some cardenolides on the K-induced contracture were examined, by using the frog's ventricular muscles. The relative potencies of four cardenolides obtained from the pA1/2 values well agreed with those reported earlier. The amount of the cardenolides required for this assay was smaller than required for other methods.

Animals↗
PubMed1980

Possible embryogenetical differences of the dog venous system in sensitivity to vasoactive substances.

Using isolated dog veins, we examined whether correlations exist between the regional differences in sensitivity to drugs and their embryogenesis. Twelve different veins were dissected. In the analysis, the data obtained previously for the inferior vena cava were also included. Spiral strips were prepared and the contractile responses to cumulative application of norepinephrine (NE), 5-hydroxytryptamine (5-HT), histamine (Hist) and acetylcholine (ACh) were recorded isometrically. For each drug, a histogram was drawn by stacking the overlapping ranges (mean +/- S.E.) of the pD2, value for each vein. The histogram indicated the number of veins which could share the same pD2 value. We obtained the following results: (1) Veins of the body wall had high sensitivity to NE (pD2 greater thn 6.40) and 5-HT (pD2 greater than 6.60) and veins of the intestinal system, except for the splenic vein, were not so sensitive to NE and 5-HT, but exhibited high sensitivity to Hist (pD2 greater than 4.60); (2) the middle segment of inferior vena cava responded similarly to portal and mesenteric veins; (3) the responses of splenic vein to the agents used were quite different from those of portal and mesenteric veins. These results suggest possible correlations between the responsiveness of venous smooth muscles and embryogenesis of the venous system.

Acetylcholine↗
PubMed1980

The age distribution of neutralizing antibodies against varicella-zoster virus in healthy individuals.

A seroepidemiological survey of varicella was made in the Nagoya area by the neutralization (NT) test. Of 1,473 recorded cases of varicella, 81.4% were under 6 years old and 9.6% were under one year old; of the 168 recorded cases under one year old, about 30% were under 5 months old. Examination of 11 pairs of mother and cord sera and 13 pairs of mother and infant sera showed that transfer of NT antibody was in general good, even in babies that were small for their age or smnall at birth after 28 weeks gestation. The transferred maternal antibody decreased rapidly, becoming undetectable in babies of 4 months old. Then with increase in age the percentgage of seropositive children gradually increased, being 53.3% at 4 to 5 years old, and 100% in those of over 9 years old, with a temporary decrease in young adults in their twenties.

Adolescent↗