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Biomedical subjects

M Tsuchiya

Publications and source records attributed to M Tsuchiya.

At least 451 records · Page 25Linked to original sources
PubMed1985

RNA tumor virus in human thymomas and thymus hyperplasias.

Human thymomas and thymus hyperplasias were examined for retroviruses. Most of these patients were complicated by systemic immunological diseases such as myasthenia gravis and pure red cell aplasia. The thymus cells were co-cultured with allogenic B cells or peripheral blood lymphocytes (PBL) pretreated with mitomycin C. Retrovirus-like particles were demonstrated in cultured thymus cells in all cases of thymomas and thymus hyperplasias examined by electron microscopy. In most cases, these particles were detected in thymus epithelial cells. Reverse transcriptase activity sedimenting at a density of 1.15-1.17 gm/cm3 in sucrose density gradients was eluted in the culture fluids. Retrovirus-like particles were demonstrated in human T cells infected with these particles. Antibodies to virus-infected T cells were detected in sera of the patients with thymoma and thymus hyperplasia. These results suggest that in thymomas and thymus hyperplasias, retroviruses that can be induced, following a proliferative stimulus, may be involved in the genesis of thymic disorders and in the pathogenesis of systemic immunological diseases.

Adult↗
PubMed1985

Muscarinic acetylcholine receptors in rat gastric mucosa. A radioautographic study using a potent muscarinic antagonist, 3H-pirenzepine.

The muscarinic cholinergic innervation of the rat gastric mucosa was investigated by localizing the muscarinic receptors using a tritiated muscarinic antagonist, pirenzepine. Radioautography was performed by freeze drying stomach tissue, which was then embedded in Epon and wet sectioned with ethylene glycol, and dry mounting on emulsion film by the wire-loop method to prevent loss of the labelled substance during fixation and the radioautographic procedure. Light and electron microscopy showed that the specific pirenzepine-binding sites were localized predominantly on parietal cells, chief cells and perivascular plexuses. Analysis of the grain distribution on parietal cells revealed that the silver grains corresponding to the pirenzepine-binding sites were mainly on the basolateral plasma membrane. On the other hand, the surface mucous or mucous neck cells had few pirenzepine-binding sites.

Animals↗
PubMed1985

Tyrosinase activity in the uveal tissue of the adult bovine eye.

Tyrosinase activity in crude extracts from various tissues of the adult bovine eye was examined biochemically. Enzyme activity was measured by using L-3,4-dihydroxyphenylalanine (L-DOPA) as substrate and determining colorimetrically by an increase in absorbancy at 400 or 475 nm. Tyrosinase activity was found in the ciliary body, iris, and choroid with the ciliary body having the highest enzyme activity. The enzyme was 1324-fold purified from the crude extract of the ciliary body by ammonium sulfate fractionation, trypsin digestion, followed by chromatography on Sephacryl S-200, hydroxylapatite, and DEAE-cellulose columns. The apparent Km value for L-DOPA was 0.2 mM and the molecular weight of the enzyme was estimated to be 70000 by gel method. The enzyme activity was markedly reduced by phenylthiourea and diethyldithiocarbamate, specific inhibitors of tyrosinase.

Animals↗
PubMed1985

Sulfonylurea stimulates liver fructose-2,6-bisphosphate formation in proportion to its hypoglycemic action.

The effects of 5 sulfonylureas on fructose-2,6-bisphosphate (F-2,6-P2) formation using isolated perfused rat liver were examined. All sulfonylureas examined stimulated dose-dependent formation of the activator in a limited range of the concentration. A maximum effect on F-2,6-P2 formation was observed at the concentration of 10(-3) M of tolbutamide or chlorpropamide, at 10(-4) M of gliclazide or acetohexamide and at 10(-6) M of glibenclamide. These concentrations of sulfonylurea correspond with those in blood when therapeutical doses of the drug are administered orally. Sulfonamide and biguanide did not show any stimulatory effect on F-2,6-P2 level. The results demonstrate that stimulation of liver F-2,6-P2 formation is a common characteristic of sulfonylureas and suggest strongly that one of the extrapancreatic actions of sulfonylurea is stimulation of F-2,6-P2 formation followed by enhancement of glycolysis and inhibition of gluconeogenesis in the liver.

Acetohexamide↗
PubMed1985

Microangiographic findings of massive intestinal bleeding in a patient with Crohn's disease: a case report.

A 16 year old man with complaints of abdominal pain, diarrhea, high fever and loss of body weight was made a diagnosis of Crohn's disease. During the administration, he had intestinal obstruction and several episodes of massive intestinal bleeding. Selective angiography of the superior mesenteric artery demonstrated the bleeding site in the ileum. Microangiography of the surgical specimens revealed abrupt interruptions of arteriae rectae in the submucosa indicating the bleeding site from the diseased intestine.

Adolescent↗
PubMed1985

Light and agonist alter vasoactive intestinal peptide binding and intracellular accumulation of adenosine 3',5'-monophosphate in the rat pineal gland.

We examined the effects of environmental light and prior treatment with an agonist on vasoactive intestinal polypeptide (VIP) binding and VIP stimulation of cAMP accumulation in the rat pineal gland. VIP binding to pinealocytes and cAMP accumulation in response to VIP were significantly increased in animals kept exposed to constant light compared to those in animals experiencing a dark night before the experiments. Scatchard analysis of [125I]VIP binding indicated the presence of two classes of binding sites: high affinity, low capacity sites and low affinity, high capacity sites. The increased VIP binding to pinealocytes in rats maintained in constant light was attributed to an increase in the number of available VIP receptors at both high and low affinity sites. The affinity of VIP binding to cells was not affected by exposure of the animals to light. VIP stimulation of cAMP accumulation was not inhibited by d,l-propranolol. Prior treatment of pinealocytes with VIP decreased [125I]VIP binding by reducing the number of receptors and significantly inhibited subsequent VIP stimulation of cAMP accumulation. Prior treatment with norepinephrine did not alter the number of VIP receptors. Our results strongly suggest that VIP is a neuromodulator of pineal function.

Animals↗
PubMed1985

Interaction of left ventricular contraction and aortic input impedance in experimental and clinical studies.

Implication of aortic input impedance and left ventricular coupling were investigated in three series of studies. In a clinical study, the ascending aortic flow velocity and pressure were simultaneously recorded from a multisensor catheter, and input impedance was calculated from 8 harmonics of aortic pressure and flow. Left ventricular wall stress was calculated from diameters and wall thickness of cineventriculogram and simultaneous recording of left ventricular pressure. In the experimental study, programmable artificial pulsatile pump was used to control pulsatile blood flow in dogs. The pressure-flow relationship in the arterial system had slightly convex curves toward the pressure axis with a critical turning pressure, so the arterial system had low output--high resistance and high output--low resistance characteristics. Therefore, the failed heart should inevitably eject the blood against stiffened vascular beds. Increased work load of the ventricle as expressed by sustained ventricular wall stress was determined mainly by the exaggerated late systolic pressure due to increased input resistance and increased low frequency pulsatile component of the input impedance. These findings are especially important for relieving additional work load of the ischemic heart, which have higher pressure wave reflection.

Animals↗
PubMed1985

Determination of the complete nucleotide sequence of the Brevibacterium lactofermentum plasmid pAM330 and the analysis of its genetic information.

The complete nucleotide sequence of the plasmid pAM330 derived from Brevibacterium lactofermentum ATCC 13869 was determined using the dideoxy chain termination method. Analysis of the sequence allowed us to observe seven open reading frames, one of which showed the presence of the promoter and the Shine-Dalgarno (SD) sequences upstream from the initiation codon.

Base Sequence↗
PubMed1985

[Prediction of coronary lesions by two-dimensional echocardiography in patients with healed myocardial infarction].

Regional left ventricular wall motion abnormalities were assessed by two-dimensional echocardiography (2-DE) in 66 patients with healed myocardial infarction (MI) and the results were compared with those of coronary angiography which was performed at nearly the same time as 2-DE. The left ventricular wall was divided into 14 segments and asynergy was assessed in each segment. To compare the severity of segmental asynergy with coronary artery lesions, relation between segments and coronary artery perfusion was assumed as follows: the anterior wall, anterior septum and apex corresponded to the anterior descending artery (LAD); the lateral and inferior walls corresponded to the left circumflex artery (LCX); and the posterior septum and inferior wall corresponded to the right coronary artery (RCA). One vessel disease: In all 24 patients with MI induced by LAD lesions, regional asynergy was identified in the anterior wall, anterior septum and apex. All patients had advanced asynergy (severe hypokinesis, akinesis or dyskinesis) except one with subendocardial infarction. Advanced asynergy was identified in the other segments including the lateral wall (one patient) and the posterior septum (11 patients), but such asynergy was not associated with that of the inferior wall. In four patients with MI induced by RCA lesions, regional asynergy appeared in localized segments of the posterior septum and inferior wall, and the asynergy was severe in all patients except one in whom collaterals were well-developed. In four patients with MI induced by LCX lesions, asynergy was observed in both the lateral and inferior walls. In only one patient, mild asynergy was identified in the apex. Multi-vessel disease: In both groups with double vessel (16 patients) and triple vessel (16 patients) disease, asynergy was recognized in the affected areas of the major coronary artery which was considered responsible for the infarction, irrespective of the severity of the coronary stenosis. Also, there was no significant correlation between the severity of coronary artery stenosis and segmental wall motion abnormalities in non-infarcted areas. No significant correlation was observed between the severity of regional wall motion abnormalities in the infarcted areas and the degree of development of collaterals. In patients with MI induced by LAD lesions, more extensive asynergy in the anterior wall and anterior septum at the basal portion was observed in the patient group with proximal stenosis than in the group with distal stenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗