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Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

At least 991 records · Page 55Linked to original sources
PubMed1984

Purification of a eukaryotic site-specific endonuclease, Endo.Sce I, from Saccharomyces cerevisiae and effectors on its specificity and activity.

A site-specific endonuclease (Endo.Sce I) which caused double-strand scission of DNA was highly purified from a eukaryote, Saccharomyces cerevisiae IAM4274. The molecular weight of the active form of Endo.Sce I was estimated to be 120,000 and 110,000 by sedimentation analysis on a glycerol density gradient and gel filtration on Ultrogel AcA34, respectively. Analysis of the fractions from the last column chromatography by polyacrylamide gel-electrophoresis in the presence of sodium dodecyl sulfate and by an assay of the endonucleolytic activities suggested that Endo.Sce I consists of two non-identical subunits with molecular weights of 75,000 and 50,000. Unlike restriction endonucleases, Endo.Sce I was active on chromosomal DNA of the cells which produced Endo.Sce I. Single-stranded DNA was not cleaved by Endo.Sce I, but inhibited the endonucleolytic activity of the enzyme on double-stranded DNA. The endonucleolytic activity of Endo.Sce I required the magnesium ions (Mg2+) as a sole cofactor; Mg2+ could not be replaced by Ca2+ or Zn2+. When Mg2+ was replaced by manganese ions (Mn2+), extensively purified Endo.Sce I cleaved double-stranded DNA at many other sites in addition to the sites at which DNA was cleaved in the presence of Mg2+. Experiments indicated that this is not the activation of contaminating endonuclease in the preparation of Endo.Sce I, but the result of relaxation in the site-specificity of cleavage.

Base Sequence↗
PubMed1984

Isotonic length transient of cat heart muscle in Ba2+-induced contracture.

To characterize mechanical properties of activated heart muscle, the length response to step (4 ms) decrease in tension in Ba2+-induced contracture in kitten papillary muscle was analyzed. The amplitudes of tension steps were varied at the maximum contracture level (Tc), different initial muscle lengths [0.90 Lmax to Lmax], and different temperatures (20-35 degrees C). When the tension decrease was less than 0.7 Tc, the length response comprised four different phases. The amplitude of shortening in the second phase, after the initial rapid shortening in the first phase, increased up to approximately 3.5% of the initial muscle length quite linearly with increasing amplitude of tension reduction. The amount of lengthening in the third phase, however, increased to a maximum (up to approximately 1.4% initial length) at the tension reduction of approximately 0.4 Tc. The third phase of lengthening was larger at shorter initial muscle length. Increasing temperature markedly decreased the amplitude and shortened the duration of the length response in the second and third phase independently of initial muscle length. Unlike that of the muscle in contracture, the length response of the resting and of the rigor muscle changed in a nearly stepwise fashion. One explanation of these phenomena is that the transient length responses following a rapid tension reduction are mostly determined by the kinetics of the attachment and detachment of cross bridges between actin and myosin filaments.

Animals↗
PubMed1984

Age-dependent changes of collagen and elastin content in human aorta and pulmonary artery.

Collagen and elastin in the arterial wall are thought to show some age-dependent changes, and to relate with development of the arteriosclerotic lesion. Both aortas and the pulmonary trunks were collected from 137 autopsy cases. Biochemical determination of collagen and elastin content was carried out. Collagen and elastin of the aorta and the pulmonary artery showed no significant age-dependent changes. Elastin content of the pulmonary artery increases with age in the adult. This paper seems to be the first report of simultaneous estimation of collagen and elastin content of both the aorta and the pulmonary artery.

Adolescent↗
PubMed1984

Inhibition of in-vitro fertilization of hamster oocytes by a thiol proteinase inhibitor.

Amongst the proteinase inhibitors tested, thiolstatin, a specific inhibitor for the thiol proteinases, leupeptin and antipain, both specific inhibitors of serine- and thiol-proteinases, strongly reduced fertilization of hamster oocytes in vitro. These results suggest the possible involvement of thiol proteinase(s), as well as acrosin, in the fertilization process. A possible role for thiol proteinase in sperm adhesion to the zona pellucida is proposed.

Animals↗
PubMed1984

Calcium pyrophosphate dihydrate deposits in the cervical ligamenta flava causing myeloradiculopathy.

Three cases of cervical myeloradiculopathy associated with multiple calcified nodules containing identified calcium pyrophosphate dihydrate (CPPD) crystals in the ligamenta flava are described, with a comprehensive review of the 12 cases of this entity reported to date. The disease is characterized by: 1) oval or triangular areas of radiodensity in the posterior aspect of the cervical canal as seen in the lateral x-ray films and laminograms; 2) hemispherical areas of high density located almost symmetrically in the paramedial portion of the posterior spinal canal on computerized tomography scans; and 3) CPPD crystals in the nodules. It occurs independently or in association with cervical spondylosis or ossification of the posterior longitudinal ligament.

Aged↗
PubMed1984

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History, Modern 1601-↗