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Biomedical subjects

H Miyata

Publications and source records attributed to H Miyata.

At least 397 records · Page 22Linked to original sources
PubMed1983

Pyruvate as a fluorescence quencher: a new spectroscopic assay for pyruvate reactions.

Pyruvate ion, which is biologically ubiquitous and participates in many metabolic reactions, was found to be an effective quencher of fluorescence. Compared to other negatively charged quenchers such as I-, pyruvate is not toxic to proteins. By adding an inert, long-lived fluorophore to systems transacting pyruvate, it is possible to estimate activity by measuring the time course of the change in pyruvate quenching of the fluorophore. The procedure is illustrated by measuring the myosin subfragment-1 ATPase activity with a high sensitivity.

Adenosine Triphosphatases↗
PubMed1983

Postnatal development of the geniculocortical projection in the cat: electrophysiological and morphological studies.

Using laminar field potential analysis, we examined responses elicited by both photic and optic nerve stimulations in 30 kittens of 0--65 days of age and in three adult cats. In adult cats, the response in the visual cortex on optic nerve stimulations is a wave complex which consists mainly of surface positive depth negative (sP-dN) potentials. By contrast, the response in neonates consists of two surface negative - depth positive (sN-dP) waves. In 2 weeks, preceding the sN-dP waves, an sP-dN wave appears. As age increases, the sP-dN wave becomes of higher voltage and the sN-dP waves become of lower voltage. Thus, the configuration of the response resembles that of adult cats in 3--4 weeks. Both photic and optic nerve stimulations elicit responses of the same configuration in the same area. The extent of the response area is exactly the same at any age as in adult cats. Using the orthograde HRP method, we examined terminals of the geniculocortical afferent in 23 kittens of 0--43 days of age. The density of labeled terminals in layer I is much higher in kittens before 1 week of age (n = 8) than in kittens after 1 month of age (n = 5), whereas the density of labeled terminals in layer IV is higher in the older kittens than in the younger kittens. These electrophysiological and morphological changes are correlated in reference to the maturation of the neuronal circuit in the visual cortex.

Aging↗
PubMed1983

Mechanisms of the potentiation of specific antitumor immunity by intratumor injection of Corynebacterium parvum.

Meth A fibrosarcoma-bearing BALB/c mice given intratumoral injections of 0.5 mg of Corynebacterium parvum showed a highly and tumor-specific transplantation antigen specifically potentiated concomitant immunity to a subsequent tumor challenge. This potentiated antitumor immunity could be locally transferred in the Winn assay to normal recipients with whole draining lymph node cells from the tumor-bearing mice, but the potentiated effect disappeared when adherent cells were removed from these cells. Moreover, the potentiated cytostatic effect on tumor cells was detected in the peritoneal macrophages but not in the nonadherent draining lymph node cells in in vitro tests. On the other hand, nonadherent draining lymph node cells from the tumor-bearing mice, when mixed with C. parvum-induced macrophages, exhibited a specifically potentiated antitumor effect. In addition, this effect was completely abolished by treatment of the draining lymph node cells with anti-Thy-1 and complement. Thus, the potentiated antitumor effect following intratumor injection of C. parvum may be ascribed to the collaboration of specifically sensitized T-lymphocytes with C. parvum-activated macrophages.

Animals↗
PubMed1982

Urinary fibrinogen and fibrin fragments in children with renal disease.

Fibrinogen fragments (X, Y, D and E) and fibrin fragments (D-dimer and E) were examined in the urine of 52 patients with various types of renal diseases. One or more of the fibrinogen fragments were detectable in all the urine specimens. D-Dimer together with fibrinogen fragments was found in 38 of the 52 patients. The clearance ratio of D-dimer to IgG, which indicates D-dimer generated in the kidney, was lower than 1 in all the patients with the minimal changes nephrotic syndrome, and was greater than 1 in the majority of patients with acute glomerulonephritis, rapidly progressive glomerulonephritis, mesangial proliferative glomerulonephritis and membranoproliferative glomerulonephritis. Our results suggest that urinary fibrin/fibrinogen degradation products (FDP) in renal diseases are derived primarily from increased filtration of FDP from the plasma through a damaged glomerular basement membrane, and that the mechanism of lysis of cross-linked fibrin deposited in the glomeruli occurs simultaneously in some types of glomerulonephritis. It seems that the determination of the clearance ratio of D-dimer to IgG may be useful in assessing the activation of the coagulation and fibrinolysis systems in the kidney in patients with renal diseases.

Adolescent↗
PubMed1982

Postnatal development of evoked responses in the auditory cortex of the cat.

Postnatal development of the auditory evoked cortical response was investigated in the cat by laminar field potential analysis. Responses were induced by electrical stimulation of the cochlear nuclear complex and by sonic stimulation under sodium pentobarbital anesthesia. As is well known, the auditory evoked cortical response in adult cats is a diphasic positive-negative wave in the superficial cortical layers and a negative-positive wave in the deeper cortical layers. By contrast, the cortical response in neonatal kittens was a monophasic negative wave in the superficial cortical layers and a positive wave in the deeper cortical layers (sN-dP wave). After 1 week, the sN-dP wave was preceded by a small wave which was positive in the superficial cortical layers and negative in the deeper cortical layers (sP-dN wave). As animals grew older, the sP-dN wave became dominant over the sN-dP wave to take an adult-like configuration of responses at 3 to 4 weeks of age. The sN-dP wave was separable from the preceding sP-dN wave by double shock stimulation at a certain time interval. Therefore, these two wave components are presumably mediated by two different types of thalamocortical projections. The level of potential reversal in each wave component shifted from the deeper cortical layers to the more superficial cortical layers during maturation. The latency of the response decreased sharply from 44 msec at birth to 11 msec by 3 weeks, and thereafter gradually to 5 msec in adulthood.

Acoustic Stimulation↗
PubMed1981

Immunoperoxidase study of alkaline phosphatase in testicular tumor.

Indirect immunoperoxidase staining was carried out on human testicular tumors using monospecific antibodies against placental (Regan) and intestinal isoenzymes of alkaline phosphatase (ALPase). The very high incidence of seminoma (approximately 90%) revealed positive staining of placental ALPase mainly on the cell membrane of tumor cells, whereas none of the seminoma showed presence of intestinal isoenzyme. Placental isoenzyme was not recognized in any embryonal carcinoma and interstitial cell tumor. The epithelial cells of the glandular elements of teratoma occasionally exhibited strong staining for intestinal ALPase and weak staining for placental ALPase. The appearance of Regan isoenzyme in seminomas might be considered possible conversion of hepatic to placental isoenzyme, a consequence of malignant transformation of spermatogenic cells. Regan isoenzyme appears to be a new tumor marker for seminoma and the frequent identification of Regan isoenzyme in seminoma may disclose a unique biologic characteristic of this germinal tumor.

Adult↗
PubMed1981

Morphological and electrophysiological evidence for axonal regeneration of axotomized cerebellothalamic neurons in kittens.

Against the current concept of abortive regeneration of axotomized neurons in the mammalian central nervous system, the occurrence of remarkable axonal regeneration of cerebellothalamic projection neurons following transection of the decussation of the superior cerebellar peduncle was proved in kittens morphologically by utilizing anterograde axonal transport of horseradish peroxidase and electrophysiologically by recording the cerebellar-induced cerebral cortical potential. Following axotomy, not only axonal regeneration occurred but also retrograde degeneration of somata which was apparently noticeable as cell loss. The extent of cerebellar nuclear cell loss was inversely related to the extent of regeneration of cerebellofugal axons.

Animals↗