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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 289 records · Page 16Linked to original sources
PubMed1988

The role of dopamine in the regulation of neurotransmitter release in spontaneously hypertensive rats.

The purpose of the present study was to analyze the influence of dopamine on norepinephrine release in resistance vessels in spontaneously hypertensive rats (SHR). Perfused mesenteric vasculature preparations from spontaneously hypertensive rats (7-10 weeks old) and age-matched normotensive Wistar Kyoto rats (WKY) were used to compare the effects of dopamine on both pressor responses and norepinephrine release. Both responses to electrical nerve stimulation were significantly greater in SHR than in WKY rats. Dopamine reduced these responses in a dose-dependent manner in WKY. However, this suppression of responses to electrical stimulation was attenuated in SHR. These results suggest that the enhanced adrenergic transmission in SHR may partly reflect impaired dopamine-mediated inhibition of nerve terminals, which would contribute to the pathogenesis of hypertension.

Animals↗
PubMed1988

Inhibitory actions of captopril on norepinephrine release from adrenergic nerve endings in spontaneously hypertensive rats.

The purpose of the present study was to investigate the mechanisms of the hypotensive actions of an angiotensin converting enzyme inhibitor of the hypotensive actions of an angiotensin converting enzyme inhibitor (captopril) in hypertension. In perfused mesenteric vasculatures from spontaneously hypertensive rats (SHR, Okamoto and Aoki strain, 10-13 weeks of age) and age-matched normotensive Wistar Kyoto rats (WKY), the effects of captopril on vascular responsiveness and norepinephrine release from the adrenergic nerve endings were examined. The vasoconstrictor responses and norepinephrine release during the electrical nerve stimulation were significantly enhanced in SHR compared to those in age-matched WKY. Captopril reduced both vasoconstrictor responses and norepinephrine release during the electrical nerve stimulation, dose-dependently. These inhibitory effects of captopril were significantly greater in SHR than in WKY. The results demonstrate that captopril affects presynaptic sites on the resistance vessels and causes a decrease in electrically-stimulated norepinephrine release from the adrenergic nerve endings. The marked reduction of both pressor responses and norepinephrine release by captopril in SHR suggests an enhanced renin-angiotensin system in the vascular walls of hypertension.

Animals↗
PubMed1988

[Effects of task attentiveness on task-irrelevant activity and boredom in the signal detection tasks].

It has been reported that subsidiary behavior, including body movements, and irrelevant thoughts occur spontaneously during a vigilance situation. These activities are called task-irrelevant activity. To examine the effects of task attentiveness on task-irrelevant activity and on the subjective feeling of boredom, 31 subjects were asked to engage in two types of signal detection tasks. The body movements were measured by recording the rotating angle of a swivel chair that the subject sat on. More task-irrelevant thoughts and subsidiary behavior occurred accompanied by higher subjective feeling of boredom in the low attentive task than in the high attentive task. These findings indicate the possibility of the task-irrelevant activity as an index of subjective boredom.

Attention↗
PubMed1988

[A case of primary hepatoma with marked reduction of the tumor after oral administration of tegafur].

A 57-year-old male complaining mainly of pain in the right terminal rib area was admitted to hospital for hepatic tumor examination. Primary hepatoma with infiltration of the inferior vena cava was diagnosed by various imaging techniques and the subject was started on a program of daily oral administrations of 800 mg of tegafur. Prior to commencing drug administration the hepatic tumor measured 112 x 80 mm; after four months of treatment the tumor was reduced to 56 x 48 mm and the infiltration in the inferior vena cava had disappeared. The tumor continued to decrease in size thereafter, and today measures 32 x 28 mm after three years of tegafur administration. The subject continues to be monitored as an outpatient. A marked reduction in the size of a hepatic tumor was observed in this case, and the administration of tegafur has proved effective in prolonging life for over three years.

Administration, Oral↗
PubMed1988

HLA and adult T cell leukaemia: HLA-linked genes controlling susceptibility to human T cell leukaemia virus type I.

HLA antigens of patients with adult T cell leukaemia (ATL), T cell malignant lymphoma (T-ML), and healthy carriers of human T cell leukaemia virus type I (HTLV-I) were investigated in an endemic area of ATL in Japan. Sixty-two patients with ATL were subdivided into three groups based on their clinical features, including two unclassified patients; 36 acute type, 10 chronic type, and 14 smouldering type. The frequency of HLA-Bw62 was significantly increased in acute ATL, compared with control (Pc less than 0.0002). Increased frequency of HLA-DQw3 was observed in patients with ATL, T-ML positive for the antibody to HTLV-I (Ab-positive), and Ab-positive healthy carriers, compared with control (Pc less than 0.001, Pc less than 0.01 and Pc less than 0.0001, respectively). In addition, class I HLA antigens of peripheral lymphocytes of patients with ATL, especially acute ATL, showed altered expression, either extra antigens or decreased antigens. Analysis of 21 families, where more than two members were Ab-positive, showed that there was no linkage between the HLA complex and susceptibility to the virus infection. In 44 couples, in which either or both spouses were Ab-positive, no association with class I HLA antigens was found in either Ab-positive spouses or Ab-negative spouses. These findings might indicate that one class II HLA-linked gene controlled susceptibility to HTLV-I infection, and another class I HLA-linked gene exerted an influence on the clinical course of ATL.

Antibodies, Viral↗
PubMed1988

Comparative diagnostic assay results for detecting antibody to HTLV-I in Japanese blood donor samples: higher positivity rates by particle agglutination assay [corrected].

Higher positivity rates for prevalence of anti-HTLV-I antibody have been reported for the gelatin particle agglutination (PA) assay when compared to that of the indirect immunofluorescence assay using acetone-fixed HTLV-I producing cells (IF-FA). To evaluate the discrepancy between these two screening methods, PA-positive/IF-FA-negative sera were tested by four additional assays for anti-HTLV-I: indirect immunofluorescence assay using live HUT102 cell membranes (IF-MA), enzyme immunoassay (EIA), radioimmunoprecipitation (RIP), and Western blotting (WB). Sera obtained from 6915 Japanese blood donors were assayed for anti-HTLV-I antibody by PA, and 389 (5.6%) were positive. These 389 sera were re-examined by IF-FA, and 29 (7.5%) were negative. Sufficient material was present for 20 of the 29 PA-positive/IF-FA-negative sera for further evaluation by the IF-MA, EIA, RIP, and WB. Fifteen (75%) of the 20 were positive by IF-MA, but only 6 (30%) were positive by EIA. Both RIP and WB confirmed 17 (85%) of the samples, with each detecting a serum that was negative by the other. Thus, 18 (90%) of the 20 were confirmed by either RIP or WB. The nonconfirmed sera were all positive on PA at low titer. These findings suggest that the PA assay is more sensitive than either IF-FA or EIA.

Agglutination Tests↗
PubMed1987

Effects of naloxone on basal and vagus nerve-induced secretions of GRP, gastrin, and somatostatin from the isolated perfused rat stomach.

The effects of naloxone, an opiate antagonist, on basal and vagus nerve-induced secretions of GRP, gastrin, and somatostatin were examined using the isolated perfused rat stomach prepared with vagal innervation. Naloxone (10(-6) M) significantly inhibited basal somatostatin secretion in the presence and absence of atropine and of hexamethonium, whereas basal GRP and gastrin secretion was not affected by naloxone. Electrical stimulation (10 Hz, lms duration, 10V) of the distal end of the subdiaphragmatic vagal trunks elicited a significant increase in both GRP and gastrin but a decrease in somatostatin. Naloxone (10(-6) M) failed to affect these responses in the presence or absence of atropine. On the other hand, when hexamethonium was infused, naloxone significantly inhibited both the GRP and gastrin responses to electrical vagal stimulation. Somatostatin secretion was unchanged by vagal stimulation during the infusion of hexamethonium with or without naloxone. These findings suggest that basal somatostatin secretion is under the control of an opiate neuron and that opioid peptides might be involved in vagal regulation of GRP and gastrin secretion.

Animals↗
PubMed1987

Effect of the alpha 2-blocker DG-5128 on insulin and somatostatin release from the isolated perfused rat pancreas.

2[2-(4.5-Dihydro-1H-imidazol-2-yl)-1-phenylethyl] pyridine dihydrochloride sesquihydrate (DG-5128) is an alpha 2-specific-adrenergic antagonist. We have studied the effect of DG-5128 on insulin and somatostatin release from the isolated perfused rat pancrease. DG-5128 stimulated somatostatin and insulin release not only at a low glucose concentration but also at a high glucose concentration. These findings suggest that an alpha 2-adrenergic receptor plays an important role in the regulation of insulin and somatostatin secretion.

Animals↗
PubMed1987

Thyroidectomy and neck dissection for the carcinoma of the thyroid gland in children.

A peculiarity in thyroid cancer in children is discussed in terms of clinical course and pathology. A case report of well differentiated papillary carcinoma of the thyroid gland in a 6-year-old boy is presented, with emphasis on the clinical course and pathology. The clinical course indicated a slowly growing, firm tumor lateral to the superior cornu of the thyroid cartilage, up to the hyoid bone. As treatment of the tumor and its lymph node metastases, a hemithyroidectomy with simple neck dissection was performed. Thyroid hormone was administered for suppression of endogenous thyroid-stimulating hormone postoperatively, and the patient tolerated this therapy well. An review of the literature dealing with the question of whether or not a radical neck dissection is appropriate in thyroid cancer in children was carried out.

Adenocarcinoma, Papillary↗
PubMed1987

A novel class of cardiotonics. Synthesis and pharmacological properties of [4-(substituted-amino)phenyl]pyridazinones and related derivatives.

A series of [4-(substituted-amino)phenyl]pyridazinones and [4-(substituted-methyl)amino]phenyl]pyridazinones was synthesized and evaluated for inotropic activity in vitro and for cardiohemodynamic effects in vivo. Above all, 6-[4-(4-pyridylamino)phenyl]-4,5-dihydro-3(2H)-pyridazinone hydrochloride (4, MCI-154) and 6-[4-(4-pyridylamino)phenyl]-5-methyl-4,5-dihydro-3(2H)-pyridazinone hydrochloride (5) showed extremely potent positive inotropic activity along with vasodilating activity. Regarding dP/dtmax (an indicator for cardiac contractility), ED30's (doses that increased dP/dtmax by 30%) of compounds 4 and 5 were 8.5 +/- 1.9 and 4.4 +/- 0.6 micrograms/kg, respectively, where that of amrinone was 471.9 +/- 94.1 micrograms/kg. Structure-activity relationships of these series are presented, and a plausible model of receptor binding is discussed.

Animals↗
PubMed1987

Plasma cholecystokinin and pancreatic polypeptide response after radical pancreatoduodenectomy with Billroth I and Billroth II type of reconstruction.

This study was conducted to elucidate plasma cholecystokinin (CCK) and pancreatic polypeptide (PP) response after pancreatoduodenectomy and to compare response of CCK and PP in patients who had pancreatoduodenectomy with Billroth I and Billroth II type of reconstruction. Basal levels of plasma CCK were significantly lower in patients who had pancreatoduodenectomy (9.6 +/- 0.8 pmol/L) than in the control (preoperative patients: 14.6 +/- 2.0 pmol/L) probably because of the removal of the entire duodenum due to pancreatoduodenectomy, since vagotomy, which is concomitantly brought about by pancreatoduodenectomy, does not appear to interfere with release of CCK. Significant amounts of CCK (integrated CCK: 497 +/- 111 pmol-120 min/L), although less amounts than in the preoperative patients (integrated CCK: 901 +/- 167 pmol-120 min/L), were still released in response to oral fatty meal after pancreatoduodenectomy. Plasma CCK response to oral fatty meal was significantly greater in patients who had pancreatoduodenectomy with Billroth I type of reconstruction (integrated CCK: 705 +/- 153 pmol-120 min/L) than in patients who had pancreatoduodenectomy with Billroth II type of reconstruction (248 +/- 63 pmol-120 min/L). Simultaneous measurement of plasma levels of PP revealed complete abolishment of PP response by pancreatoduodenectomy. Since PP secretion can be produced by vagal stimulation, it is most likely that the decreased PP secretion is due to vagotomy rather than removal of the duodenum and pancreas. Significant amounts of CCK released after pancreatoduodenectomy, in which the main sources of release of CCK are removed, may suggest the compensatory mechanism of the remnant upper small intestine. This study also suggests the necessity of re-evaluating Billroth I type of anastomosis as a physiologic reconstruction procedure for the remnant alimentary tract after pancreatoduodenectomy.

Adult↗