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Biomedical subjects

C Yamamoto

Publications and source records attributed to C Yamamoto.

At least 199 records · Page 11Linked to original sources
PubMed1991

Induction of hsp 72/73 by herbimycin A, an inhibitor of transformation by tyrosine kinase oncogenes.

Herbimycin A, which has been known to inactivate and degrade p60v-src tyrosine kinase, induced an elevated synthesis of a protein with a molecular size of 70 kDa in A431 human epidermoid carcinoma cells. This protein showed the same migration distance on SDS-polyacrylamide gel electrophoresis as that of the protein induced in the cells by heat shock treatment, and this 70-kDa protein was identified as a member of the heat shock protein 70 family (hsp70) through immunoprecipitation with anti-hsp72/73 antibody and partial digestion with V8 protease. The induced level of the 70-kDa protein was dependent on the length of period and the concentration of herbimycin A treatment. Cellular fractionation and indirect immunofluorescence analyses revealed that the 70-kDa protein induced by herbimycin A was localized in the cytoplasm, in contrast to the nuclear distribution of hsp70 induced by heat treatment. Induction of hsp70 by herbimycin A was also observed in several other cells, including HeLa S3 cells, chicken embryo fibroblasts, NIH3T3 cells, and Rous sarcoma virus-transformed NIH3T3 cells.

Antibiotics, Antineoplastic↗
PubMed1991

Effect of lead on the glycosaminoglycans metabolism of bovine aortic endothelial cells in culture.

We investigated the effect of lead nitrate (0.1, 1.0, 10 or 20 microM) on the metabolism of glycosaminoglycans (GAG) in confluent cultures of bovine aortic endothelial cells. It was found that lead at 10 and 20 microM significantly decreased the accumulation of [35S]sulfate-labeled GAG ([35S]GAG) both in the cell layer and the medium after a 24-h culture. A time course study showed that 10 microM lead decreased the accumulation of [3H]glucosamine-labeled GAG both in the cell layer and the medium after 24 h and longer. The release of [35S]GAG from the cell layer during the last 3 h of a 24 h culture was not changed by lead. The detachment of [3H]thymidine-labeled cells from the monolayer was unaffected by lead. It was shown that lead at 10 microM decreased both heparan sulfate and the other GAG in the cell layer; the former was more sensitive to lead treatment. Lead at 20 microM and below failed to increase the release of lactate dehydrogenase, suggesting that non-specific cell damage was not caused by lead. From these results, it was suggested that lead decreases endothelial cell heparan sulfate content through a decrease in the GAG production without a non-specific cell damage. Lead may be a risk factor of vascular disorders.

Animals↗
PubMed1991

Caroli's disease: scintigraphic and radiographic findings.

Caroli's disease is a rare congenital anomaly of the liver. Since new diagnostic techniques for the evaluation of hepatic disease have been introduced, the number of reported cases of Caroli's disease has been gradually increasing. This report describes the case of a 13 year old girl with nausea, vomiting, fever and hepatomegaly. The diagnosis of Caroli's disease was established by ultrasonography and CT scan. The complications and management are discussed. The important points in management are to relieve symptoms and to conduct regular examinations by ultrasonography for the early detection of hepatobiliary carcinoma.

Adolescent↗
PubMed1991

Low molecular weight heparin enhances prostacyclin production by cultured human endothelial cells.

Confluent cultures of vascular endothelial cells derived from the human umbilical vein were incubated in a serum-free medium in the presence of low molecular weight heparin (LMWH) with molecular weights of 4000-6000 dalton (Da), or of unfractionated heparin (UFH) with average molecular weight 12,000 Da, and prostacyclin production was determined by radioimmunoassay for 6-keto-prostaglandin F1 alpha, the stable metabolite of prostacyclin. LMWH at 1 U/ml as anti-factor Xa activity significantly increased prostacyclin production after 6h or longer; however, UFH at 1 USP U/ml did not induce such a significant change. The LMWH-induced increase in prostacyclin production occurred at 0.1 U/ml and above after 6 h of treatment. Since prostacyclin is both a potent inhibitor of platelet aggregation and a vasodilator, it was suggested that the increased endothelial cell prostacyclin production induced by LMWH may be a component of the anticoagulant activity of the drug.

Cells, Cultured↗
PubMed1991

Immunohistochemical detection of NSE and S-100 protein in the thalamic VB nucleus after ablation of somatosensory cortex in the rat.

The ventrobasal (VB) nucleus has been studied after ablation of somatosensory cortex in 39 adult rats by the application of both NSE- and S-100 protein-immunoreactivity. Both NSE- and S-100 protein-immunoreactivity are confirmed in neurons and reactive astrocytes in the affected VB area and its surroundings, respectively. The NSE-immunoreactivity first starts in the affected VB at seven days postlesion and appears more active in its surrounding area at fourteen days postlesion. At the twenty-eight days, NSE-positive neurons are reduced in number and their stainability becomes weak. The time course of NSE-immunoreactivity is based on the progression of neuronal damage. And it is conceivable that the accumulation of NSE in neurons correlates with the regeneration. The S-100 protein-immunoreactivity is also first detected in the affected area at seven days postlesion and spread in its surrounding area at fourteen days postlesion. At twenty-eight days, S-100 protein-positive astrocytes are reduced in cell volume and their processes become thin. The time course of S-100 protein-immunoreactivity correlates with the degree of astrocytic hypertrophy. And the potent accumulation of S-100 protein appears after the onset of gliosis. The onset of neuronal damage and the repair process can be followed with immunohistochemical technique for both NSE and S-100 protein morphologically. Namely, NSE and S-100 protein can be of potential use as markers for destructive processes in the CNS.

Animals↗
PubMed1991

Immunohistochemical detection of GABA in rat striatum by intraperitoneal injection of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine).

To study MPTP-induced muscular rigidity, we try to detect the changes of both dopamine (DA) and GABA within rat striatums by immunohistochemical means. A high dose (30 mg/kg) of MPTP i.p. injected into rats produces behavioral abnormalities (tremor and ataxia), and higher doses (greater than 60 mg/kg) develop an acutely muscular rigidity without producing a measurable histological change. GABA is induced in the striatum of 4 MPTP (30 mg/kg) i.p. treated-rats developed tremor and ataxia. But the animals recovered to an apparently normal state and are not showed GABA-immunoreactivity. Dense GABA-immunoreactivity is observed in the striatum developed muscular rigidity, when the animals are injected with 60 mg/kg MPTP i.p.. At this time, their striatums show slight decrease of DA-immunoreactivity in medium sized-spiny neurons. The results give some insight as to how DA and GABA function within the striatum with respect to the development of neuronal abnormalities. It is also suggested by our behavioral and immunohistochemical studies that effects induced by the depletion of DA within the striatum may be mediated through the inhibition of the striato-nigral GABAergic pathway, which in turn may lead to an activation of the nigrothalamic or nigro-collicular GABAergic pathway. This study indicates that the role of striatal GABAergic transmission is important in the development of muscular rigidity. The activity within the striatum can be followed with immunohistochemical technique for GABA morphologically.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

Applicability of Pascal distribution to quantal analysis for non-stationary release of neurotransmitter.

In order to assess the applicability of theoretical distributions to statistical analysis of neurotransmitter release, we made mathematical approaches such as derivation of frequency-generating function of the distributions, and obtained a result that a frequency distribution of the number of quanta released by the consecutive stimulations is described by a Pascal distribution when the Poisson parameter m varies temporally according to a gamma (gamma) distribution. Therefore, if the experimentally obtained distribution fits with a Pascal distribution, this suggests that non-stationary nature of the release mechanism.

Animals↗
PubMed1990

[In vivo insulin sensitivity in adrenodemedullated rats].

Insulin sensitivity and responsiveness were determined in adrenal demedullated rats (ADMX) with euglycemic insulin clamp technique. Adrenal medulla was extirpated bilaterally a week before the study. Catheters were placed at right atrium via right jugular vein for sampling blood and at inferior vena cava via femoral vein for the infusion of insulin and glucose solution. Insulin was infused at rates of 4.4, 8.8, 14.7, 29.3, 88.0, 293.0 mU/kg/min. Blood was collected every five min. during the clamp and glucose infusion rate was modulated to control the blood glucose concentrations at fasting levels. Glucose metabolism was calculated from the amount of glucose infused from 60th to 120th min. during the euglycemic clamp. The results obtained were as follows: 1. Glucose metabolisms of ADMX in each infusion rate of insulin, 4.4, 8.8, 14.7, 29.3, 88.0, 293.0 mU/kg/min were 5.2 +/- 0.5, 12.5 +/- 0.5, 17.6 +/- 1.2, 19.8 +/- 2.3, 29.0 +/- 1.5, and 25.2 +/- 1.9 mg/kg/min, respectively. 2. Glucose metabolisms of control group in each dose were 6.6 +/- 0.4, 9.0 +/- 0.9, 18.5 +/- 1.2, 23.4 +/- 2.4, 24.6 +/- 1.1, and 27.0 +/- 1.3 mg/kg/min, respectively. 3. Significant difference (p less than 0.01) in glucose metabolism between ADMX and control was observed at the insulin infusion rate of 8.8 mU/kg/min which might be equivalent to physiological hyperinsulinemia. 4. There were not any differences in insulin responsiveness between both groups. These results suggest that epinephrine regulates insulin sensitivity under physiological hyperinsulinemic condition via defects of insulin receptors.

Adrenal Medulla↗
PubMed1990

Glutathione conjugation of methazolamide and subsequent reactions in the ciliary body in vitro.

Conjugation reaction of methazolamide with glutathione and its subsequent reactions were studied in vitro. Glutathione, cysteinylglycine, and cysteine conjugates of methazolamide were chemically synthesized. All of the three compounds showed absorbance below 330 nm, with maximal absorbance at approximately 300 nm. At the wavelengths below 220 nm, absorbance was proportional to the number of the amino acids each compound had. Amino acid analysis of the glutathione conjugate showed that the conjugation reaction involved the cysteine residue of glutathione. In order to identify the chemical structure of the reaction product, cysteine conjugate was subjected to infrared, proton nuclear magnetic resonance, and mass spectral analyses. These studies indicated that the cysteine conjugate was S-(5-acetylimino-4-methyl-delta 2-1,3,4-thiadiazolinyl)cysteine. The reaction with glutathione was not catalyzed by glutathione S-transferases, but proceeded in the absence of the enzyme. The glutathione conjugate was degraded by bovine ciliary body homogenate to the cysteinylglycine conjugate and then to the cysteine conjugate.

Animals↗
PubMed1990

Immunohistochemical detection of laminin and vimentin in the thalamic VB nucleus after ablation of somatosensory cortex in the rat.

The ventrobasal (VB) nucleus has been studied after ablation of somatosensory cortex in 62 adult rats by the application of both vimentin and laminin immunoreactivity. Both vimentin- and laminin-immunoreactivity are confirmed in reactive astrocytes (GFAP-positive cells) in the affected VB area and its surroundings. The vimentin immunoreactivity first gives rise in the affected VB at seven days postlesion and appears more active in its surrounding area at fourteen day postlesion. At the twenty-eight days, vimentin-positive astrocytes are reduced in cell volume and their processes become thin. The laminin immunoreactivity is also first detected in the affected area at seven days postlesion and spread in its surrounding area at fourteen days postlesion. At the twenty-eight days, laminin-positive astrocytes are reduced in cell volume and their processes become thin. The time course of both vimentin and laminin immunoreactivity correlates with the degree of astrocytic hypertrophy. Acquisition of vimentin is one of the typical astroglial reactions by brain injury (5). The laminin in the reactive astrocyte contributes to the temporal activation for the regeneration. But the neurons in the affected VB area mostly die. And reactive domain in its surrounding area, will support the repair of affected BV area and form glial scar. The induction of laminin might be involved in scar formation (8).

Animals↗
PubMed1989

Simultaneous recording of presynaptic spikes and excitatory postsynaptic potentials from monosynaptically connected hippocampal neurons.

A technique has been devised to activate single granule cells in the hippocampus, and to record simultaneously spikes from the particular granule cell and excitatory postsynaptic potentials from a monosynaptically connected CA3 neuron. The unitary excitatory postsynaptic potentials (EPSPs) sustained for long observation periods, and increased in size with increases in stimulus frequency and in external Ca2+ concentration. This technique may be useful for quantal analysis of transmission through the synapse between mossy fibers and CA3 neurons.

Action Potentials↗
PubMed1989

Modulation of stretch reflex by anticipation of the stimulus through visual information.

A stretch stimulus was applied to the right elbow flexor by the free gravitational fall of a weight. The subject was instructed to flex the elbow joint to lift the weight quickly (resist task) or to extend the elbow joint to overtake the falling weight (assist task) as the voluntary reaction to the stretch stimulus. In the resist task, when the subject could predict the time of stretch stimulus onset by watching through the mirror the behavior of the experimenter going to give the stretch stimulus, the integrated EMG (I-EMG) of M2 (50-80 ms after the stimulus onset) and M 3 (80-100 ms) components of stretch reflex were significantly enhanced compared with when the experimenter's movements were invisible to the subject, while no differences were observed in the background discharge before the stretch stimulus onset (BGA) and the short latency reflex (M 1). In the assist task, the M 2 and M 3 were depressed when the visual information about the stimulus presentation was available, while the BGA and M 1 were unchanged. From these results, it is suggested that (1) the preparatory set should be classified into two categories, i.e., task-related "topographical set" and timing-related "chronographic set", and (2) visual information about the process of stimulus presentation can modulate the reflex activity of stretched muscle allowing the required task to be executed efficiently by accurately anticipating the stretch stimulus onset.

Adolescent↗