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Biomedical subjects

T Kihara

Publications and source records attributed to T Kihara.

At least 163 records · Page 9Linked to original sources
PubMed1983

Distribution of glucose-6-phosphatase activity in mice studied by in vitro whole-body autoradiography.

The distribution of the glucose-6-phosphatase (G6Pase) activities was demonstrated by in vitro whole-body autoradiography. Relatively high activities were observed in the liver, kidney, and small intestine of mice. However, these organs did not exhibit uniform activity throughout. The activity of the liver was found heterogeneous, but that of the duodenum and jejunum were higher than for those of other parts of the intestine. G6Pase activity was higher in the cortex of the kidney than in the medulla. In addition to these observations, it was also found that the skeletal system had high radioactivity. These results were similar to those from biochemical experiments. This method of in vitro whole-body autoradiography would seem to be of value in studying macroscopic distributions of other enzyme activities in organs as well as in whole-body.

Animals↗
PubMed1982

A device for the reduction of population dose.

Conventional dental radiographic procedures do not permit direct visualization of the radiation field or the central ray. As a result, it is necessary to use a beam diameter larger than the film in order to prevent an unnecessarily high number of cone cuts or other errors during visual alignment of the cone and film. The modification of a conventional dental x-ray cone which permits the central ray to be depicted by a beam of light is described. The use of the device significantly reduced the number of cone cuts, even when small beam diameters were used. Visualization of the central ray improved radiographic accuracy and has the potential to significantly reduce the over-all dose to the population by reducing the size of the field used for dental radiography.

Equipment Design↗
PubMed1981

Effect of ethinyl estradiol on development of mouse fetuses.

Pregnant ICR/JCL mice were given orally 0.02, 0.3, or 2.0 mg/kg body weight/day of ethinyl estradiol in olive oil or vehicle alone on day 11 through day 17 of pregnancy. Pregnant mice of another group received a single oral dose of ethinyl estradiol on day 8 or day 11 of pregnancy. A lethal effect on fetuses of both groups with single and continuous exposure to ethinyl estradiol was observed in a dose-response relationship. Growth suppression of fetuses was only found at term in a dose-response relationship following continuous exposure to ethinyl estradiol. Hypertrophic nipples were seen in 42% of surviving female fetuses prenatally exposed to 2.0 mg/kg of ethinyl estradiol singly on day 11 of gestation. There was not an increase in other congenital malformations in any of the treated groups. These findings indicate that administered ethinyl estradiol can affect the developing mouse embryo but the embryotoxic doses in the mouse are substantially greater than the usual therapeutic or contraceptive doses in the human.

Abnormalities, Drug-Induced↗
PubMed1980

A new approach to time-resolved studies of ATP-requiring biological systems; laser flash photolysis of caged ATP.

2-Nitrobenzyl derivatives have been used for several years as photolabile protecting groups in synthetic organic chemistry. Recently, P3-1-(2-nitro phenylethyladenosine 5'-triphosphate "caged ATP" was synthesized and its photolysis was shown to generate ATP in situ. This and related reactions have great potential for structural and kinetic studies of both intact and soluble biological systems and it is thus important to define the kinetic characteristics of the photolytic reaction. Caged ATP (2.5 mM) was photolyzed at 347 nm by a single 30-nsec pulse from a frequency-doubled ruby laser of 25 mJ energy to generate 500 microM ATP. The kinetics of the overall reaction were determined by monitoring the kinetics of ATP-induced dissociation of actomyosin, a reaction of known kinetic characteristics. Release of 500 microM ATP was found to be controlled by a process having a rate constant of 2.2 X 10(9) [H+] sec-1 at 22 degrees C at pH 5.8-9.5, which corresponds to 220 sec-1 at pH 7. This process is believed to be the breakdown of an aci-nitro compound, which was identified on the basis of its spectral properties and the photochromicity of related 2-nitrobenzyl compounds.

Actomyosin↗