Search PubMed⌕ Search

Biomedical subjects

Y Kikuchi

Publications and source records attributed to Y Kikuchi.

At least 919 records · Page 51Linked to original sources
PubMed1979

An analysis of water movement between myocardial tissue and capillary blood during reactive hyperemia.

The colloid osmotic pressure (COP) of blood from the great cardiac vein was continuously measured by means of a membrane colloid osmometer during the reactive hyperemia following temporary occlusion of the anterior descending branch of the left coronary artery in anesthetized open-chest dogs. The COP increased sharply after releasing the occlusion, then decreased below the preocclusion level before gradually returning to it. These findings indicate that a measurable amount of water moved from the capillary blood into the myocardial tissues and then flowed back slowly into the capillary blood. To analyse the factors affecting this water movement, a method is proposed in which the Starling mechanism is combined with the interstitial volume elasticity and a steady-state solution of a Navier-Stokes equation. The pressure observed with a catheter wedged into a branch of the great cardiac vein was used as a measure of capillary perfusion pressure. During the coronary arterial occlusion, the filtration constant increased while the volume elasticity of the myocardial interstitial spaces decreased rapidly. The filtration constant and volume elasticity of the interstitial space under normal conditions were approximately estimated to be 2.4 X 10(-11) cm/(sec.dyn.cm-2) and 1.1 X 10(7) dyn.cm-2, respectively.

Animals↗
PubMed1979

Non-uniform oxygen supply to the left ventricular myocardium by systolic perfusion of coronary artery.

The left anterior descending branch of the coronary artery (LAD) of anesthetized, open-chest dogs was perfused by intraventricular pressure (systolic perfusion) and aortic blood pressure (aortic perfusion) alternately. When the LAD perfusion was switched from aortic perfusion to the systolic one, the subendocardial PO2 decreased to 9.8 mmHg, on an average, in 1 to 2 min from the initial level of 18.9 mmHg obtained during the aortic perfusion. On total occlusion of LAD, the subendocardial PO2 fell to 4.5 mmHg, while the subepicardial PO2 showed no significant change. These results suggest that a small amount of oxygen is transported to the subendocardium during the systolic phase despite the impaired blood flow to the subendocardium and that the oxygen supply to subepicardium can be supported even though the LAD perfusion is restricted to the systolic phase.

Animals↗
PubMed1979

In vivo and in vitro studies of experimental ovarian adenocarcinoma in rats.

When 7,12-dimethylbenz[a]anthracene-impregnated sutures were directly applied to the ovarian parenchyma of 8-week-old Sprague-Dawley rats (the clipping method), adenocarcinomas developed in 29 (39%) of the 75 rats during the 50-week observation period. When 20-methylcholanthrene was used, adenocarcinomas developed only in 1 (3%) of the 31 rats. Thus, the clipping method using 7,12-dimethylbenz[a]anthracene is satisfactory as an animal model of ovarian adenocarcinoma which comprises 85 to 90% of human malignant ovarian tumors. On the other hand, attempts were made to isolate cloned cell lines from these experimental ovarian adenocarcinomas in vitro, and two cloned cell lines were obtained. They were epithelioid and produced undifferentiated adenocarcinomas by back-transplantation into isologous newborn rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

Glycolipids in human lung carcinoma of histologically different types.

Glycolipids were isolated from primary human lung carcinoma tissue of various histologic types: adenocarcinoma, squamous cell carcinoma, and undifferentiated small cell carcinoma. Each type of carcinoma had a characteristic glycolipid pattern. The major glycolipids isolated were ceramide monohexosides, ceramide dihexosides, ceramide trihexosides, globoside, and hematoside. Squamous cell carcinoma and undifferentiated small cell carcinoma showed marked increases of ceramide monohexosides and dihexosides. Adenocarcinoma had a much higher level of the sulfatide (ceramide 3-sulfate-galactoside) as compared to squamous cell carcinoma, undifferentiated small cell carcinoma, or normal lung tissue. Embryonic tissue had more significant levels of sulfatide than did the other carcinomas. Adenocarcinoma had significantly lower levels of glycolipids due mainly to a decrease in the amount of ceramide monohexosides and dihexosides and hematoside.

Adenocarcinoma↗
PubMed1978

The bacteriophage lambda int gene product. A filter assay for genetic recombination, purification of int, and specific binding to DNA.

Bacteriophage lambda int gene is required for the integration of viral DNA into the chromosome of Escherichia coli. We have extensively purified the product of the int gene (Int) from a lysogen of E. coli that constitutively expresses this gene. Int was assayed by its ability to promote integrative recombination of supertwisted substrate DNA in vitro using a new method based on filter trapping of a recombinant product DNA. In order to catalyze integrative recombination, Int must be supplemented by other factors that can be extracted from bacterial host cells. By itself, purified Int does not demonstrate detectable endonuclease, exonuclease, or nicking-closing activities. However, Int does make stable complexes with double-stranded lambda-DNA containing an attachment site, the region at which recombination takes place. No stable complexes are observed between Int and lambda-DNA without an attachment site or between Int and DNA containing the bacterial site of integration. Int, therefore, appears to be a specificity element that relies on additional factor(s) to provide or activate the catalytic functions required for recombination.

Chromosomes, Bacterial↗
PubMed1978

Reexamination of paternal age effect in Down's syndrome.

Paternal age distribution for 1279 cases of Down's syndrome born in 1952--1968 was compared with the corresponding distribution for the general population, corrected for the maternal age as well as for the year of birth of the patients. Although there was no difference in the mean paternal age, the two distributions differed significantly, largely due to the excess of fathers aged 55 years and over and to the deficit of those aged 40--44 years in the patients born to mothers aged 30 years and over. The overall pattern of the relative incidence of Down's syndrome with advancing paternal age, with maternal age controlled, seems consistent with the hypothesis proposed by Stene et al. (1977). It increased from 0.8 for fathers aged 20--24 years slowly up to 1.2 for those aged 45--49 years, though with an intermediate drop to 0.8 at the age of 40--44 years, and then sharply to 2.4 for those aged 55 years and over. This rising pattern of the relative incidence with paternal age was essentially the same for the patients born in 1952--1960 and for those born in 1961--1968, although the slope was less steep in the latter than in the former group.

Adolescent↗
PubMed1978

A new method for the preparation of mammalian spermatogonial chromosomes.

After the seminiferous tubules were minced and washed with phosphate-buffered saline to remove sperms, spermatids and spermatocytes (Hoo and Bowles, 1971), they were repeatedly treated with 0.1% trypsin solution to liberate spermatogonia. It was concluded that the spermatogonial chromosomes can be analysed much more easily and accurately by this procedure than by previous ones.

Animals↗
PubMed1978

Mutagenicity of benzotrichloride and related compounds.

Benzotrichloride (BTC), benzal chloride (BDC), benzyl chloride (BC) and benzoyl chloride (BOC) were surveyed for their mutagenicity in microbial systems such as rec-assay using Bacillus subtilis and reversion assays using E. coli WP2 and Ames Salmonella TA strains with or without metabolic activation in vitro. BTC and BDC required metabolic activation for their mutagenic activities in several strains of E. coli and Salmonella. The mutagenic metabolites of these compounds may not have been produced by hydrolysis. BC was weakly mutagenic without metabolic activation. Only BOC exhibited no mutagenic activity in the detection procedures used. The mutagenic metabolite of BTC might be very unstable under our experimental conditions. The strain E. coli WP2 try hcr was more sensitive than E. coli B/r WP2 try (hcr+) with regard to the mutagenicity of BTC.

Bacillus subtilis↗
PubMed1978

Addition of mononucleotides to oligoribonucleotide acceptors with T4 RNA ligase.

RNA ligase induced by bacteriophage T4 catalyzed the addition of nucleoside 5',3'-diphosphates to oligoribonucleotide acceptors in the presence of ATP. The reactions proceeded in equimolar concentrations of donors and acceptors. Several oligonucleotides of defined sequence were synthesized by this method in yields of 28-68%. The enzyme required the phosphate ester at the 3' position of the donor molecule, nucleoside 5',2'-diphosphates being unable to serve as donors. Thymidine 5',3'-diphosphate was active as a donor for the enzyme. The ligation product, (Ap)2ApCp, was also obtained from the reaction of (Ap)2A and 5'-adenylylated cytidine 5',3'-diphosphate (A5'pp5'Cp) with RNA ligase in the absence of ATP. These results show that the minimal substrate for RNA ligase is a nucleoside 5',3'-diphosphate.

Adenosine Triphosphate↗
PubMed1978

Enzymatic synthesis of a segment of bacteriophage Qbeta coat protein gene.

The oligoribonucleotide, A-A-A-C-U-U-U-Gp, constituting a segment of RNA bacteriophage Qbeta coat protein gene was efficiently synthesized at a milligram scale by a combination of enzymatic methods using bacteriophage T4 RNA ligase and the thermophilic polynucleotide phosphorylase. A-A-A-Cp was synthesized from A-A-A and pCp by the newly developed mononucleotide addition method using T4 RNA ligase in a yield of 83%, followed by dephosphorylation with bacterial alkaline phosphatase to obtain A-A-A-C. pU-U-U-Gp was synthesized from pU-U-U and GDP by the simultaneous action of polynucleotide phosphorylase and RNase T1 in a yield of 32%. finally, the two oligonucleotides (A-A-A-C and pU-U-U-Gp) were ligated with T4 RNA ligase and the octanucleotide, A-A-A-C-U-U-U-Gp, was obtained in a yield of 85%.

Alkaline Phosphatase↗