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Biomedical subjects

M Miyata

Publications and source records attributed to M Miyata.

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

HRP studies on thalamocortical neurons related to the cerebellocerebral projection in the monkey.

In monkeys (Macaca fuscata and mulatta), horseradish peroxidase (HRP) was injected in the cerebral cortices, areas 4 (medial and lateral parts), 5, 6 and 9 (a part just rostral to area 6), in which stimulation of cerebellar nuclei was known to elicit superficial or deep thalamocortical responses. Retrogradely labelled thalamic neurons consisted of two separate clusters of neurons, as judged by the continuity of labelled thalamic cells; lateral (VApc, VLo, VLm, VPLo, VPLc, LP) and medial (VAmc, X, Pcn, Cl, Pulo, Pulm, Pull, MD) ones. In each cluster, neurons in the medial portion tend to project on more rostral cerebral cortices than those in the lateral portion. In the lateral cluster, medially and laterally located thalamic neurons tend to project, respectively, on lateral and medial parts of a cortical area. Retrograde and anterograde labelling revealed that thalamocortical and corticothalamic projections are mostly reciprocal except CM which receives massive terminals from area 4 but projects scarcely on to the area. According to the references which have demonstrated terminations of cerebellothalamic neurons, thalamocortical neurons relaying the cerebellocerbral projection are presumed to be included in both the medial and lateral thalamic cell clusters mentioned above. The organization of cerebellothalamocortical projections appears more complicated and elaborated than that reported before.

Animals↗
PubMed1983

The mode of cerebellar activation of neurons in the cat motor cortex: an intracellular HRP study.

Intracellular recordings and morphological identification of neurons by using intracellular HRP staining were performed in the cat motor cortex. By cerebellar stimulation, stellate cells in layers II-III, pyramidal cells in layer III and fast pyramidal tract neurons (PTNs) were activated with short latency and fast rising EPSPs, while pyramidal cells in layer II and slow PTNs showed a wide range of latency and slow rising EPSPs. This difference may be related to activation through the deep and superficial thalamocortical projections.

Animals↗
PubMed1983

Diagnostic monitoring of plasma levels of glucose and insulin during surgery for insulinoma.

With serial measurement of blood sugar levels during surgery in three patients with solitary insulinoma, we confirmed the location, then later, the complete elimination of the insulin-secreting tumor. Following vigorous massage of the tumor, blood sugar levels decreased while the levels progressively increased within 20 min following removal of the tumor. Subsequent measurement of simultaneous plasma insulin levels provided further confirmation. Plasma levels of insulin increased in accordance with massage of the tumor. Prior to removal of the tumor, the levels progressively decreased to less than the preoperative levels. For success in detecting slight changes in blood sugar levels secondary to increase or decrease of insulin secretion during surgery for insulinoma, (1) controlled infusion of glucose to keep blood sugar levels around 80 mg/dl and (2) frequent rapid determination of blood sugar levels are considered to be important.

Adenoma, Islet Cell↗
PubMed1983

Retinal degeneration in rats exposed to an organophosphate pesticide (fenthion).

Pigmented (Long-Evans) and albino (Wistar) rats were chronically exposed to an organophosphate pesticide (fenthion). Fenthion (50 mg/kg) was administered subcutaneously twice a week for 1 year; the total dosage for each animal ranged from 1.6 to 1.8 g. Concurrent with the fenthion administration, the amplitude of the scotopic electroetinogram (ERG) gradually declined, disappearing by the 12th month in all treated pigmented rats. For the albino experimental rats, however, the ERG amplitude disappeared as early as the 6th month in 7 out of 15 treated animals. Funduscopically, degeneration of the retina was observed in all rats when ERG responses had disappeared. Histopathological studies confirmed degeneration of the sensory retina and marked abnormalities in the pigment epithelium cells. Treated pigmented rats also had reduced a rhodopsin concentration in the retina by the 3rd month even though the photoreceptors were structurally normal. Interestingly, the plasma vitamin A levels remained normal and liver stores of vitamin A actually increased during the course of the study. Levels of butylcholinesterase in plasma and liver, on the other hand, were extremely reduced after 3 months of fenthion treatment. In general, the biochemical and functional (ERG) changes appeared before any structural damage could be detected in the retina.

Animals↗
PubMed1983

Isolation and characterization of a post-proline cleaving enzyme and its inhibitor from sperm of the ascidian, Halocynthia roretzi.

A post-proline cleaving enzyme and its endogenous inhibitor have been demonstrated to be present in sperm of the ascidian, Halocynthia roretzi. The enzyme was extracted with artificial sea water from frozen and thawed sperm and isolated from accompanying acrosin-like and chymotrypsin-like enzymes by DEAE-cellulose chromatography. It was then separated from the endogenous inhibitor by ammonium sulfate fractionation and DEAE-Sephacel chromatography. Three subsequent chromatographic operations using hydroxylapatite, Sephadex G-150 and Z-Gly-Pro-Leu-Gly-aminohexyl-Sepharose yielded the highly purified enzyme. The molecular weight and isoelectric point of the enzyme were estimated to be 66,000 and 5.5, respectively. The pH optimum of the activity was 7.0. The enzyme was inactivated with diisopropylphosphorofluoridate, phenylmethylsulfonyl fluoride, Z-Gly-Pro-chloromethyl ketone and sulfhydryl-directed reagents; these inhibitor susceptibilities were similar to those reported for the enzymes of mammalian origins. The ascidian enzyme hydrolyzed oxytocin, angiotensin II, luteinizing hormone releasing hormone and neurotensin at the carboxyl side of proline residues. The endogenous inhibitor was heat stable. The molecular weight of its main component was estimated to be about 8,000. The presence of salt at high concentrations weakened the enzyme-inhibitor interaction. Z-Gly-Pro-chloromethyl ketone inhibited fertilization of the ascidian, suggesting possible involvement of the post-proline cleaving enzyme in fertilization.

Animals↗
PubMed1983

BCG-induced susceptibility of mice to challenge with Pseudomonas aeruginosa.

Mice infected with Mycobacterium bovis, BCG, were shown to be highly susceptible to subsequent challenge with Pseudomonas aeruginosa. The susceptibility was characterized by the enhanced mortality and shortened survival after challenge with P. aeruginosa. BCG-treated mice did not show any enhanced susceptibility to challenge with Gram-positive bacteria such as Staphylococcus aureus or Listeria monocytogenes. BCG-treated mice eliminated P. aeruginosa from their organs in a pattern similar to that in untreated mice. There was no significant difference in the bactericidal activities of polymorphonuclear cells and macrophages between BCG-treated and untreated mice. An equal amount of endotoxin was detected by the Limulus lysate assay in the blood of both BCG-treated and untreated mice after challenge with P. aeruginosa. The enhanced susceptibility induced by BCG pretreatment could be decreased when the mice were rendered LPS-tolerant by injections of small amounts of LPS. These results suggest that BCG-induced susceptibility to P. aeruginosa can be ascribed to an enhanced susceptibility to the lethal effect of LPS produced by challenge bacteria, and not to the impairment of the ability to eliminate infected bacteria.

Animals↗
PubMed1983

Natural and antibody-dependent cellular cytotoxicity of polymorphonuclear leukocytes.

Cytotoxic activity of polymorphonuclear leukocytes (PMN) in the peripheral blood of patients with various diseases was demonstrated to K562 cells (natural cytotoxicity, NC) and the antibody-coated P815 cells (antibody-dependent cellular cytotoxicity, ADCC), using a 51Cr-release method. The NC values of normal PMN were lower than those of normal lymphocytes with mean values of 5.0% and 30%, respectively. The NC values of patients' PMN were also lower in malignancy, chronic hepatitis and connective tissue diseases. The ADCC values of normal PMN were moderately high with a mean value of 16.0%, which was almost a half of normal lymphocytes. Higher ADCC values of PMN were found in patients with chronic hepatitis, SLE and Behcet's disease, and in these cases the ADCC values of their lymphocytes were extremely low. The supernatants of PMN mix-cultured with unlabeled K562 or the antibody-coated P815 cells were fairly cytotoxic to both cells, though the similar supernatants of lymphocytes were cytotoxic only to K562 cells, but not to the antibody-coated P815 cells.

Animals↗
PubMed1983

[Orthotopic liver transplantation in the rat using cuff techniques for anastomoses of three hepatic vessels].

This report describes in detail a method for orthotopic liver transplantation in the rat. Cuff techniques were applied to all three anastomoses at the supra- and infrahepatic inferior vena cava and the portal vein. In the last 40 grafts, the survival rate after one week was 85% and the cumulative survival rate after nine months was 54.4%. This method simplified the technique and shortened the time of grafting, eliminating microvascular suture techniques. This model could be of use for the study of rejection phenomenon and enhancement after allografting as well as evaluation of viability of isograft after preservation.

Animals↗