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Biomedical subjects

M Tsuda

Publications and source records attributed to M Tsuda.

At least 559 records · Page 31Linked to original sources
PubMed1983

Effects of pressure and temperature on the M412 intermediate of the bacteriorhodopsin photocycle. Implications for the phase transition of the purple membrane.

The effects of pressure and temperature on the decay kinetics of the M412 (M) intermediate in the photocycle of bacteriorhodopsin were studied to provide information about the phase transitions of the purple membrane lipids. The activation volume (delta V++) for the decay of M is expected to be different below and above a phase transition. However, no abrupt change in delta V++ was found from 3.5 degrees to 60 degrees C. But a sharp break was observed in a plot of the logarithm of the rate of M decay vs. pressure. Extrapolation of this break point to standard atmospheric pressure gives a temperature of -42 degrees C, which probably corresponds to the phase transition of the purple membrane lipids. This conclusion is supported by studies of the effect of pressure on the M kinetics of bacteriorhodopsin incorporated into dimyristoylphosphatidylcholine vesicles, whose phase transition has previously been characterized.

Bacteriorhodopsins↗
PubMed1983

Presence of 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, a precursor of a mutagenic nitroso compound, in soy sauce.

After treatment with nitrite, Japanese soy sauce was strongly mutagenic to Salmonella typhimurium TA100 without S9 mixture. Two precursors of the mutagen were isolated from Japanese soy sauce, and these were identified as (-)-(1S,3S)-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid [(-)-(1S,3S)-MTCA] and its stereoisomer (-)-(1R,3S)-MTCA. After treatment with nitrite, 1-mg samples of these compounds induced 17,400 and 13,000 revertants of TA100, respectively, without S9 mixture. Quantitative analysis of various kinds of soy sauces produced in Japan showed the presence of 82-678 micrograms of MTCA per ml. The mutagenicities of these compounds with nitrite accounted for 16-61% of the total mutagenicity of soy sauce with nitrite. Most soy sauces produced in the United States were less mutagenic than those produced in Japan and little, if any, of these two precursors of the mutagen was found in them. A major reaction product of (-)-(1S,3S)-MTCA and nitrite was a compound having a nitroso substitution at position N-2, but this compound was not mutagenic. Thus, the mutagen(s) formed from (-)-(1S,3S)-MTCA and nitrite was a minor product(s), and its specific mutagenic activity must be very high.

Biotransformation↗
PubMed1983

Transcription modulation in vitro of the fibroin gene exerted by a 200-base-pair region upstream from the "TATA" box.

We have previously reported that the 5'-flanking sequence upstream from the "TATA" box modulates the faithful transcription initiation of the fibroin gene in a homologous whole cell extract prepared from the silk glands, whereas such a modulating effect is not observed in a HeLa cell extract. Subsequently we have determined that major signals responsible for the modulating effect are located within a 200-base-pair region upstream from the TATA box, mainly in a distal region between nucleotide positions -238 and -116 and in a proximal one between -73 and -53. Inversion of the sequence element -234 to -66 did not alter its modulating effect. A similar modulating effect by the upstream region of the sericin gene was also observed in the silk gland extract but not in the HeLa cell extract. In contrast, a modulating effect by the upstream region of the adenovirus 2 major late gene was observed in the HeLa cell extract but not in the silk gland extract. Thus, the modulating effect by the upstream regions of these genes is exerted only in their own homologous extracts.

Animals↗
PubMed1983

Changes in the profiles of rodent plasma lipoproteins and apolipoproteins after cholesterol feeding.

Profiling of plasma lipoprotein distribution and apolipoprotein analysis were carried out semi-quantitatively by strictly controlled gel-filtration and SDS slab-gel electrophoresis for rats (Sprague-Dawley rats and ExHC rats), mice and hamsters. The effects of cholesterol feeding on lipoprotein and apolipoprotein patterns of these animals were also studied. HDL were major lipoproteins in all the animals. Hamsters had the most abundant lower density lipoproteins among the rodents with the ratio of cholesterol content between high density lipoproteins and lower density lipoproteins being about 1:1. After cholesterol feeding, the cholesterol content of lower density lipoproteins increased in all the animals. The increase was the greatest in ExHC rats and the least in mice. The profiling methods employed should be of value in determining the changes in the lipoprotein and apolipoprotein patterns of both experimental animals and man.

Animals↗
PubMed1983

Ordering of the flagellar genes in Pseudomonas aeruginosa by insertions of mercury transposon Tn501.

The flagellar genes of Pseudomonas aeruginosa PAO cluster on the chromosome at two distinct regions, region I and region II. The order of the flagellar cistrons in this organism was established by using transducing phage G101 and plasmids FP5 and R68.45. A method to insert transposon Tn501 near the fla genes was devised. We obtained two strains in which Tn501 was inserted at sites close to the flagellar cistrons in region II. We isolated Fla mutants in which the chromosomal segment between the two Tn501 insertion sites was deleted. Using Tn501-encoded mercury resistance as an outside marker, we determined the order of 9 of the 11 flagellar cistrons in region II as follows: puuF-region I-flaG-flaC-flaI-flaH-flaD-flaB-flaA-flaF-flaE-pur-67. By using phage G101-mediated transduction, the mutation converting monoflagellated bacteria into the multiflagellated (mfl) form was closely linked to the five fla cistrons in region I. Using mfl as an outside marker, we determined the order of the five cistrons as follows: puuF-flaV-flaZ-flaW-flaX-flaY-region II. The mfl mutation was shown to be either located within the flaV cistron or linked very closely to this cistron. No linkage was observed in transductions between any of the fla cistrons in region I and any of the fla cistrons in region II.

Chromosome Mapping↗
PubMed1983

Transductional analysis of the flagellar genes in Pseudomonas aeruginosa.

Complementation in bacteriophage E79 tv-l-mediated transduction and the phenotypic properties of the flagellar genes in Pseudomonas aeruginosa PAO were investigated by using 195 flagellar mutants of this organism. A total of 15 fla. 1 mot, and 2 che cistrons were identified. At least 5 fla cistrons (fla V to flaZ) and one mot cistron resided in one region, and at least 10 fla cistrons (flaA to flaJ) and two che cistrons (cheA and cheB) resided in another. The flaC mutants exhibited cistron-specific leakiness on motility agar plates. The flaE cistron may be the structural gene for the component protein of the flagellar filament. The cheA mutations, which resulted in pleiotropic phenotypes for flagellar formation, motility, and taxis, belonged to the same complementation group as the flaF mutations; that is, we inferred that cheA and flaF are synonymous.

Flagella↗
PubMed1983

Genetic mapping of bra genes affecting branched-chain amino acid transport in Pseudomonas aeruginosa.

Pseudomonas aeruginosa PAO mutants defective in the transport systems for branched-chain amino acids were isolated and characterized. Two mutations in strains selected for trifluoroleucine resistance, braA300 and braB307, were mapped in the met-9020-dcu-9108 and the nar-9011-puuC10 region, respectively. The mutation loci in strains selected for azaleucine resistance, braC310 and bra-311 through bra-314, were all located near the fla genes, with an order of region I fla-bra-region II fla. Strains with braA300 showed a marked reduction in the high-affinity branched-chain amino acid transport system (LIV-I) and a considerable decrease in the lower-affinity system (LIV-II). Strains with braB307 were found to be defective in the LIV-II system. Strains selected for azaleucine resistance were all defective only in the LIV-I system and fell into three phenotypically distinct classes. Strains with braC310 produced a binding protein for leucine, isoleucine, valine, alanine, and threonine (LIVAT-BP) altered in binding ability, indicating that the braC gene is the structural one for the LIVAT-BP. Strains with bra-311 or bra-312 showed a complete loss of production of the LIVAT-BP. Strains with bra-313 or bra-314 produced normal levels of functional LIVAT-BP, suggesting that these mutations are located in a gene(s) other than braC.

Amino Acids, Branched-Chain↗
PubMed1983

[New chemotherapeutic method for the treatment of tracheal and bronchial cancers--nebulization chemotherapy].

A new chemotherapeutic method for the treatment of tracheal and bronchial tree cancers, and of lung cancer with invasion to the bronchial tree has been developed. It is named Nebulization Chemotherapy or NC therapy. This method is based on vaporizing the anti-cancer drug (5-Fluorouracil, 5-FU) solution with a supersonic nebulizer, and inhaling the vaporized anticancer drug trans-orally through the bronchial tree. Patients were divided into two groups. The first group, where NC therapy was the main method of treatment used, included 6 patients. Of these, 4 (2CR and 2PR) showed a good anti-cancer response to the treatment. The other was a group receiving combination treatment with our CMAF protocol (cis-platinum, mitomycin C, adriamycin and 5-FU) and NC therapy. This group included 6 patients, 5 of whom (2CR, 2PR and 1MR) showed a remarkable anti-tumor response. Side-effects to the bronchial tree, pulmonary parenchyma or other systemic toxicity have not been noted so far after NC therapy. However, a few patients showed glottitis. Only trace amounts of circulating 5-FU were detected in serial serum samples.

Adenocarcinoma↗
PubMed1983

Different uptake in rat peritoneal macrophages of beta-very low density lipoprotein prepared from Sprague-Dawley rats and hypercholesterolemic rats (ExHC rats).

Rat beta-migrating very low density lipoprotein (beta-VLDL) was obtained from both ExHC rats and Sprague-Dawley rats which had been fed a cholesterol diet for 4 days, and was incubated with peritoneal macrophages from both kinds of rat to compare the cellular uptake of these lipoproteins. ExHC rat beta-VLDL was taken up by the cells three to five times as well as Sprague-Dawley rat beta-VLDL. Uptake depended solely on the lipoproteins used and not on the cells. Both lipoproteins seemed to be slightly different from each other in apolipoprotein composition. This stimulated uptake may explain the aortic lipid deposits found in ExHC rats with dietary hypercholesterolemia.

Animals↗
PubMed1983

Presence of N-nitroso-L-thioproline and N-nitroso-L-methylthioprolines in human urine as major N-nitroso compounds.

Unknown N-nitroso compounds were found in human urine of healthy volunteers by gas chromatography-thermal energy analysis. These compounds were identified as N-nitroso-L-thioproline and cis- and trans-N-nitroso-L-methylthioprolines by gas chromatography-mass spectrometry. The precursors of these new N-nitroso compounds may be formed by the reactions of L-cysteine with formaldehyde and acetaldehyde in the human body.

Chromatography, Gas↗
PubMed1982

Efficient and strand-selective in vitro transcription initiation by purified RNA polymerase II from a unique site of the fibroin gene.

Using purified RNA polymerase II and the cloned fibroin gene of supercoiled form, we found a novel in vitro transcription initiation site. An analysis by S1 nuclease mapping showed that the transcripts synthesized by RNA polymerase II purified from three different sources gave primarily a common protection band, the 5' terminus of which was located at a specific site about the nucleotide position +25 of the fibroin gene. Such a transcript was not detected in the in vivo RNA; however, this site-specific transcription revealed a coding-strand selectivity and a high efficiency accounting for nearly 90% of total in vitro RNA synthesis. An analysis using a series of 5' deletion mutants of the fibroin gene indicates that this transcription initiation depends on a unique DNA sequence about the nucleotide position +25, which includes an inverted repeat and a sequence homologous to that around the in vivo initiation site of the fibroin gene.

Animals↗