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Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 379 records · Page 21Linked to original sources
PubMed1986

Effect of methylmercury on the activity of glutathione peroxidase in rat liver.

The effect of methylmercury on the activity of glutathione peroxidase in rat liver was studied in vivo. A daily dose of 10mg methylmercuric chloride/kg body weight was administered subcutaneously to 15 male Wistar rats for 10 days, and the glutathione peroxidase activity in the liver was measured to compare with the control activity. A marked decrease was observed in the glutathione peroxidase activity in the experimental animals, which measured as low as 40% in comparison to that in the control animals. It can be speculated that the inhibition of glutathione peroxidase activity plays a significant role in the development of mercury toxicity and that the protective effect of selenium and vitamin E on the mercury intoxication might be partly due to preserving the glutathione peroxidase activity in the antioxidative defense mechanisms.

Animals↗
PubMed1986

Paradoxical responses of plasma cortisol, adrenocorticotropic hormone and growth hormone to thyrotropin-releasing hormone and luteinizing-hormone-releasing hormone in anorexia nervosa patients.

Abnormalities of hypothalamic-pituitary function in patients with anorexia nervosa (AN) have been reported previously. Since atypical responses to thyrotropin-releasing hormone (TRH) and luteinizing-hormone-releasing hormone (LHRH) have been observed in other disease states, hormonal responses to these hypothalamic peptides in 60 otherwise unstressed young women with anorexia nervosa were studied. Sixteen patients demonstrated a growth hormone (GH) response to TRH and 10 showed an increase in GH after LHRH. Five patients had an increase in cortisol after TRH, 2 of whom showed GH response, and 2 patients demonstrated a cortisol response to LHRH, 1 of whom had a GH response. Variable TSH responses to TRH were observed in the study but there was no correlation with the occurrence of GH or cortisol responses. GH responses to TRH and LHRH were typically not seen in the same patients, nor were they predictive of a cortisol response to the same stimulus. These data add to the evidence for an abnormal hypothalamic-pituitary regulation in AN.

Adolescent↗
PubMed1986

Thyroid function and histology in forty-five patients with hyperthyroid Graves' disease in clinical remission more than ten years after thionamide drug treatment.

Thyroid function was determined in 45 patients with hyperthyroidism due to Graves' disease who had been diagnosed and treated with thionamide drugs between 1965 and 1971 and had remained clinically euthyroid for greater than 10 yr after discontinuation of therapy. Physical examination revealed that only 2 patients had signs of mild hyperthyroidism; all others were euthyroid. Measurements of serum concentrations of thyroid hormones and TSH revealed elevated free T4 index values and serum T3 in 3 (6.7%), T3 toxicosis in 4 (8.9%), and subclinical hypothyroidism in 2 patients (4.4%). The remaining 36 patients were biochemically euthyroid. TRH tests were performed in these 36 patients, and hyporesponsiveness was found in 3 and hyperresponsiveness in 5 patients. T3 suppression tests were performed in 15 of the 36 patients; 10 were suppressible and 5 were nonsuppressible. All suppressible patients responded to TRH. Large needle biopsies performed in 8 biochemically euthyroid patients and 1 patient with subclinical hypothyroidism revealed chronic lymphocytic thyroiditis in 7 and normal biopsies in 2 patients. Diffuse epithelial hyperplasia was not found in any of the specimens. Antithyroid antibody titers were significantly higher than in 1972 at the time of discontinuation of therapy using the same methods. These results suggest that Graves' disease may evolve into chronic thyroiditis in some patients who are in permanent remission, and some patients in apparent permanent remission have hyperthyroidism and concomitant chronic thyroiditis.

Amides↗
PubMed1986

Effects of intravenous injection of isosorbide dinitrate on the cardiovascular system.

An assessment of the acute hemodynamic effect of intravenous isosorbide dinitrate (ISDN) was performed with a Mikro-tip angiocatheter in 10 patients during the diagnostic cardiac catheterization. Both left ventricular (LV) systolic pressure (SP) and end-diastolic pressure (EDP) were decreased by 2 mg of ISDN. Cardiac index, stroke work index and heart rate did not change significantly, and neither systemic vascular resistance nor pulmonary arteriolar resistance was reduced. Isovolumic phase and ejection phase indices of contractility were not altered. End-diastolic stress, an accurate index of preload, was reduced significantly (47.0 +/- 27.6 to 28.7 +/- 24.6 g/cm2, p less than 0.01), and mid-systolic stress, an index of afterload, was also reduced (371 +/- 102 to 332 +/- 85 g/cm2, p less than 0.05). No undesirable side effects were noted during this study. We concluded that bolus intravenous (IV) ISDN safely reduced both preload and afterload. As 2 mg of IV ISDN had no significant change on SVR, a larger dose of ISDN bolus injection might be needed for a significant arterial vasodilating effect. Bolus IV ISDN seems to be very effective in cases in which rapid reduction of LV filling pressure is mandatory.

Adult↗
PubMed1986

Histological findings of the right and left ventricular myocardium and clinical follow up in idiopathic ventricular tachycardia.

In order to evaluate the etiology of so-called idiopathic ventricular tachycardia, endomyocardial biopsies were performed in four patients with electrocardiographically documented recurrent and sustained ventricular tachycardia. During the episodes of ventricular tachycardia, standard ECG showed a QRS pattern of right bundle branch block with left axis deviation in two patients and left bundle branch block in two patients. The episodes were associated with palpitation, dyspnea and hypotension in all cases. No organic heart disease was detected by physical examination, chest X-ray films, echocardiograms, left ventriculograms or coronary cineangiograms. His bundle electrograms showed blocks at various sites in the atrioventricular conduction system. The biopsy specimens revealed nonspecific myocardial degeneration in the right and left ventricles. These findings suggest mild but wide-spread myocardial damage in both the working myocardium and the conduction system. The clinical course of these patients appeared benign according to follow-up data of one to nine years' duration. None developed overt clinical signs of dilated, hypertrophic or restrictive cardiomyopathy.

Adult↗
PubMed1986

Cardiovascular effects of a new inotropic agent, denopamine (TA-064); with reference to it's effects on cardiac hemodynamics and metabolism.

A new inotropic agent, denopamine (TA-064) was shown to have a strong positive inotropic effect. Its effect on cardiac hemodynamics and metabolism was evaluated by using wall stress and direct measurement of myocardial oxygen consumption. With plasma concentration of denopamine (21-29 ng/ml on average), attainable by one single oral dose (10 mg), the positive inotropic effect was evident by the significant increase in peak (+)dp/dt (+15% increase from control), and shortening velocity of the left ventricle (+39%), when heart rate or blood pressure was not altered significantly. End diastolic stress and end systolic stress of the left ventricle, defined as indices of preload and afterload, respectively, were reduced significantly. The reduction of preload (-51%) was the result of improved left ventricular filling, and the reduction of afterload (-23%) was due to the increased contractility. Neither coronary sinus blood flow not aortocoronary AV O2 defference was changed. Consequently, myocardial oxygen consumption remained unaltered. When the dose is chosen properly, denopamine is able to exert salutary effects in patients with severe heart failure.

Administration, Oral↗
PubMed1986

Effects of noxious stimuli and anesthetic agents on substance P content in rat central nervous system.

Effects of noxious electrical tooth stimulations and intraarterial administration of bradykinin or inhalation of volatile anesthetics on substance P content in the diencephalon-mesencephalon, pons-medulla and the spinal cord were examined in the rat. Noxious stimulation by electrical long duration stimulation (type 2) of tooth pulp caused an increase of substance P content in the ponsmedulla. Inhalation of volatile anesthetics such as methoxyflurane and diethylether produced an increase of substance P content in the spinal cord; and in addition, methoxyflurane produced a decrease of substance P content in ponsmedulla. However, halothane did not produce any changes in substance P content in any parts of the central nervous system (CNS). These results suggest that volatile anesthetics such as diethyl-ether and methoxyflurane act on the substance P neuron and may modulate pain transmission through the action of substance P in the pons-medulla or the spinal cord.

Anesthetics↗
PubMed1986

Imaging and uptake mechanism of 131I-meta-iodobenzylguanidine in medullary thyroid carcinoma.

131I-meta-iodobenzylguanidine (131I-MIBG) was also taken up by medullary thyroid carcinoma (MTC) as well as by pheochromocytoma in two patients with Sipple's syndrome. However, the mechanism of 131I-MIBG uptake by MTC has not been clarified yet. We measured tissue catecholamine levels in three MTC, since MTC can produce several active substances. Catecholamines were detected in various amounts in all MTC, but not in normal thyroid tissues. These findings suggest that MTC can produce catecholamines and therefore, 131I-MIBG is taken up and stored in catecholamine vesicles of MTC, like pheochromocytoma and neuroblastoma. We conclude that 131I-MIBG may be applied not only to diagnosis but also for the treatment of patients with MTC.

3-Iodobenzylguanidine↗
PubMed1986

[Regional cerebral blood flow measurement in brain tumors].

The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of 133Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; Correlation of the flow data within tumors to the angiographic tumor stains, Influence of tumors on the cerebral blood flow of the normal brain tissue, Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors.

Adult↗
PubMed1986

[A phase II study of epirubicin in malignant lymphoma].

A new anthracycline analog, epirubicin (4'-epi-Adriamycin) was evaluated at eleven institutes in a phase II clinical study in patients with malignant lymphoma. Epirubicin was administered intravenously mainly with using the following two regimens; 50 to 60 mg/m2 every three weeks and 40 mg/m2 weekly. A total of 46 cases were entered into the study and 41 cases were evaluable. Clinical responses, complete plus partial remissions, were observed in 27 cases (65.9%) with 8 of these showing complete remission. There was no significant difference of response between the two regimens. Response rates taking into account previous chemotherapy were 90.9% (10/11) in previously nontreated cases, 61.9% (8/13) in cases previously treated with non-anthracyclines and 52.9% (9/17) in cases treated with anthracyclines. The major adverse effect was bone marrow suppression; leukopenia was observed in 83.8%, anemia in 60.5% and thrombocytopenia in 15.4%. Other adverse effects frequently observed were anorexia (59.0%), nausea-vomiting (48.8%) and alopecia (55.6%). These adverse effects seemed milder than those produced by doxorubicin. The results indicated that epirubicin seemed to be a markedly useful drug against malignant lymphoma.

Adult↗