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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 163 records · Page 9Linked to original sources
PubMed1994

Glutamatergic regulation of [3H]-noradrenaline release in the medulla oblongata of normotensive and spontaneously hypertensive rats.

OBJECTIVE: To assess in vitro the role of glutamate receptors in the regulation of noradrenaline release from the medulla oblongata of normotensive and hypertensive rats. DESIGN AND METHODS: The effects of L-glutamate (an endogenous ligand for glutamate receptors), glycine (an allosteric agonist for the N-methyl-D-aspartate type of glutamate receptors) and MK-801 (an antagonist for N-methyl-D-aspartate receptors) on [3H]-noradrenaline release were examined in slices of rat medulla oblongata. RESULTS: L-Glutamate elicited [3H]-noradrenaline release from slices of rat medulla oblongata in magnesium-free medium. Glycine also increased the release of noradrenaline. Moreover, the effect of L-glutamate on noradrenaline release was significantly potentiated by glycine. MK-801 inhibited the increase in noradrenaline release evoked by L-glutamate. In spontaneously hypertensive rats (SHR) the facilitatory effect of L-glutamate on noradrenaline release was significantly more pronounced than in Wistar-Kyoto (WKY) rats. Furthermore, glycine alone and in combination with L-glutamate increased the noradrenaline release to a greater extent in SHR than in WKY rats. CONCLUSION: The present results show that the excitatory amino acids might increase noradrenaline release from rat medulla oblongata, which was partially dependent on the N-methyl-D-aspartate type of glutamate receptors. The greater effect of L-glutamate and glycine in SHR suggests that these amino acids might be involved in the regulation of noradrenaline release in the medulla oblongata of hypertension.

Animals↗
PubMed1994

Investigation of type IIC von Willebrand disease.

Type II von Willebrand disease (vWD) is characterized by qualitative abnormality of von Willebrand factor (vWF). It is characterized by the absence of the largest, or the largest and intermediate-size plasma vWF multimers. Type IIC vWD is a very rare variant subtype. We report the tenth case of type IIC vWD who is a 32-year-old Japanese with a history of lifelong mild bleeding problems. The multimeric analysis of vWF of the patient's plasma revealed that the multimers were composed of the increased smallest multimer and progressively decreased larger multimers, with each multimer replaced by a single band instead of a normal triplet structure. The family study highly suggested that the propositus is the first case of homozygote for type IIC vWD gene, although previous studies have suggested that type IIC vWD is due to double heterozygosity of two different mutant genes. The patient's von Willebrand factor antigen showed a slight response to 1-deamino-8-D-arginine vasopressin (DDAVP), whereas his ristocetin cofactor showed no response. The patient responded very well to an intermediate-purity factor VIII concentrate, and then underwent cholecystectomy without bleeding problems.

Adult↗
PubMed1994

[Mitral valve replacement and closure of atrial septal defect in the case associated with Marfan syndrome].

This is a case report of 8-years-old boy, who was diagnosed mitral regurgitation, secundum type of atrial septal defect and annulo-aortic ectasia in association with Marfan syndrome. His diagnosis was confirmed at the age of 6 years when cardiac catheterization was carried out. Atrial septal defect was closed using PTFE patch (0.2 mm in thickness). His diseased mitral valve was replaced with CarboMedics prosthesis 27 mm in diameter. Because of intact aortic valvular function, we left the ectatic aorta alone at present time for future procedure. His postoperative course was uneventful. He is active and doing well at present and has been followed-up at the outpatient clinic routinely. He might be having to require AVR and graft implantation for ectatic ascending aorta.

Child↗
PubMed1994

[Surgical treatment of abdominal aortic aneurysm associated with idiopathic thrombocytopenic purpura and consumption coagulopathy: a case report].

A 68-year-old man who had abdominal aortic aneurysm (AAA) associated with idiopathic thrombocytopenic purpura (ITP) and consumption coagulopathy was successfully operated upon. The count of platelet was improved from 1.4 x 10(4)/microL to 8.0 x 10(4)/microL by the preoperative treatment with gamma-globulin (400mg/kg/day for 5 days) and heparin sodium (10000-15000 unit/day). Abdominal aortic aneurysm was replaced with a Y-shaped knitted Dacron graft, and splenectomy was performed for ITP. No severe hemorrhagic diathesis was encountered during and after the operation. This is the first report of surgical treatment of AAA associated with ITP and consumption coagulopathy.

Aged↗
PubMed1993

[Transthoracic percutaneous ethanol injection for the liver].

Fourteen normal rats were received with percutaneous ethanol injection (PEI) in the subphrenic region of the liver, using a 22G fine needle, via the thoracic cage. The procedure was successful in all rats. Minor complications were observed in 3 rats: these included pneumothorax, hemorrhage, and pleural effusion. However all complications had disappeared in the follow up CT one week after the procedure. The transthoracic approach is a useful and safe method of PEI for the subphrenic region of the liver.

Animals↗
PubMed1993

Analysis of anti-Tax antibody of HTLV-I carriers in an endemic area in Japan.

Sera from 1197 adult residents in Miyazaki district, an area in Japan endemic for human T-cell leukemia virus type I (HTLV-I), were tested for anti-Tax antibody by the recombinant Tax (r-Tax) Western blot assay. Among HTLV-I-seropositive individuals, including 21.5% of 484 males and 28.6% of 713 females, the prevalence of anti-Tax antibody were 59.6% and 58.3% respectively, with no apparent difference in age. There was a significant 6-fold difference in the prevalence of anti-Tax among seropositive subjects with titer > or = 1:8192 (84.6%) compared with those with the lowest titer of 1:16 (14.3%), suggesting the increased production of antibodies to viral structural proteins in anti-Tax-positive individuals. Furthermore, among those anti-Tax-positive subjects, the intensity of serum reactivity to r-Tax protein in the high antibody titer (1:1024 or higher) group was significantly stronger than that in the lower antibody titer (1:512 or lower) group. We also found that 1.6% (14/889) of individuals without detectable levels of HTLV-I antibody had anti-Tax antibody. HTLV-I pro-viral DNA signals could not be detected in DNA sample from the lymphocytes of these individuals by the nested polymerase chain reaction method. Further evaluation is needed to clarify the significance of an anti-Tax-only status population in which HTLV-I is endemic.

Adult↗
PubMed1993

Peliosis of the spleen with intraperitoneal hemorrhage.

We encountered a patient with steroid-related peliosis of the spleen, a rare disease characterized by multiple blood-filled cavities in the splenic parenchyma, with spontaneous intraperitoneal hemorrhage. The ultrasonographic, computed tomographic, and angiographic images were compared with pathologic findings of the material obtained surgically.

Aged↗
PubMed1993

Suppressive effect of GABA on insulin secretion from the pancreatic beta-cells in the rat.

In order to investigate a possible role of GABA in the regulation of insulin secretion, we have studied the effect of GABA on insulin secretion from the isolated perfused rat pancreas in vitro and on the changes in the cytoplasmic Ca2+ of Beta-cells from the isolated rat islets. When glucose is present, GABA caused a dose dependent inhibition of the first phase of arginine-induced insulin secretion during the range of 10-1000 microM, but GABA did not affect arginine-induced insulin secretion in the absence of glucose. GABA inhibited not only the first phase but also the second phase of glucose-induced insulin secretion. A GABAB-receptor agonist, baclofen, also inhibited both phases of insulin secretion induced by 16.7 mM glucose. Furthermore, GABA inhibited the rise in cytoplasmic Ca2+ of Beta-cells in response to 16.7 mM glucose. These studies indicate that GABA decreases Beta cell secretory activity mainly in response to glucose. These inhibitory effects of GABA on insulin secretion may be mediated through GABAB-receptor and the inhibition of the rise in cytoplasmic Ca2+.

Animals↗
PubMed1993

Display of MR angiograms: maximum intensity projection versus three-dimensional rendering.

OBJECTIVE: The purpose of this study is to clarify the most useful technique of MR imaging in demonstrating the collateral venous pathways due to portal hypertension. SUBJECTS: Twenty-eight cirrhotic patients with collateral venous pathways due to portal hypertension and three patients without them were studied. We evaluated the detectability of collateral vessels of flow-enhanced transverse MR images by time of flight effect, projection MR angiography using the maximum intensity projection technique and three-dimensional (3D) computer graphic images, by using the arterial portography as the standard. RESULTS: Flow-enhanced transverse MR images showed 98% of the collateral vessels detected by angiography, however, the connection of each vessel was obscure. Fully 81% of the collateral vessels were seen by projection MR angiography, and 98% of them by the 3D computer graphic images. CONCLUSION: The detectability of collateral vessels of 3D computer graphic imaging was better than that of the projection MR angiography and was as accurate as that of transverse MR imaging. 3D Computer graphic images provided complex anatomical information in a more easily understood fashion than either transverse MR images or projection MR angiography.

Adolescent↗
PubMed1993

Effects of neurotensin on norepinephrine release in blood vessels of spontaneously hypertensive rats.

The present study was performed to investigate the effects of neurotensin on noradrenergic transmission in blood vessels of hypertension. In the perfused mesenteric vasculatures prepared from spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto (WKY) rats, we examined the influences of neurotensin on vascular responsiveness and norepinephrine release from adrenergic neurons. In studies with male standard Wistar rats, endogenous norepinephrine release during periarterial nerve stimulation was inhibited by neurotensin in a dose-dependent manner. Vasoconstrictor responses to electrical nerve stimulation were also inhibited by neurotensin. In SHR, the stimulation-evoked pressor responses and norepinephrine release were enhanced compared with WKY rats. The suppression of these responses by neurotensin was significantly less in SHR than in WKY rats. These results show that neurotensin could have a modulatory effect on noradrenergic activity and cause a decrease in stimulation-evoked norepinephrine release from vascular adrenergic neurons. The lesser reduction of pressor responses and norepinephrine release by neurotensin in SHR might suggest an insufficient regulation of vascular adrenergic transmission by the peptide hormone in hypertension.

Adrenergic Fibers↗
PubMed1993

Heterosexual transmission of human T cell leukemia/lymphoma virus type I among married couples in southwestern Japan: an initial report from the Miyazaki Cohort Study.

To identify factors that may modify the heterosexual transmission of human T cell leukemia/lymphoma virus type I (HTLV-I), 534 married couples enrolled in the Miyazaki Cohort Study between November 1984 and April 1989 were studied: 95 husband HTLV-I-seropositive (H+)/wife seropositive (W+), 33 H+/W-, 64 H-/W+, and 342 H-/W-. After 5 years of follow-up, seven seroconversions occurred and clustered significantly among serodiscordant pairs (relative risk [RR] = 41.2); the rate of transmission was 3.9 times higher if the carrier spouse was male (P = .19). Among H+/W- couples, husband's age > or = 60 years strongly predicted seroconversion in the wives (RR = 11.5). All 4 carrier husbands whose wives seroconverted had HTLV-I titers > or = 1:1024 (P = .04) and were anti-tax antibody positive (P = .06). In cross-sectional analysis, total parity also was independently associated with wife's serostatus but only length of marriage with husband's. Overall, sexual transmission of HTLV-I was primarily from older infected husbands to their wives, with husbands' viral status being an important factor.

Adolescent↗
PubMed1993

Effects of verapamil and diltiazem on dopamine release in the central nervous system of spontaneously hypertensive rats.

1. The purpose of the present study was to investigate the effects of Ca(2+)-antagonists (verapamil and diltiazem) on dopamine release in the central nervous system in hypertension. 2. Striatal slices obtained from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were prelabelled with [3H]-dopamine, and superfused with Krebs-Ringer solution in vitro. The slices were stimulated electrically at a frequency of 1 Hz. 3. Stimulation-evoked release of [3H]-dopamine from striatal slices was significantly decreased in SHR compared with WKY rats. 4. Exposure of slices to verapamil and diltiazem significantly increased the stimulation-evoked [3H]-dopamine release. The facilitatory effects of the Ca(2+)-antagonists on dopamine release were significantly greater in SHR than in WKY rats. 5. Because central nervous system dopaminergic mechanisms appear to be depressor, the results suggest that the pronounced effects of verapamil and diltiazem on dopamine release in SHR might be involved in the central hypotensive mechanisms of the Ca(2+)-antagonists.

Animals↗
PubMed1993

Effects of bradykinin on [3H]-norepinephrine release in rat hypothalamus.

1. We examined the regulatory actions of bradykinin on norepinephrine release in the hypothalamus of rats. 2. Bradykinin increased the stimulation-evoked [3H]-norepinephrine release from hypothalamic slices of Sprague-Dawley rats in a dose-dependent manner (1 Hz: S2/S1 ratio, mean +/- s.e.m., control 0.868 +/- 0.016, n = 6; bradykinin 1 x 10(-6) mol/L 1.039 +/- 0.018, n = 6, P < 0.05; bradykinin 3.3 x 10(-6) mol/L 1.130 +/- 0.064, n = 6, P < 0.05). The basal release of [3H]-norepinephrine was not affected by the peptide. 3. Bay K 8644, a dihydropyridine-sensitive calcium channel agonist, significantly potentiated the facilitatory effect of bradykinin on norepinephrine release, although Bay K 8644 by itself had no significant effect. By contrast, nicardipine, a dihydropyridine-sensitive calcium channel blocker, reversed the increase in norepinephrine release induced by bradykinin and Bay K 8644. 4. These results indicate that bradykinin may increase norepinephrine release in rat hypothalamus, partially mediated by interactions with dihydropyridine-sensitive calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Rapid formation of multicellular spheroids of adult rat hepatocytes by rotation culture and their immobilization within calcium alginate.

Tyrosine aminotransferase (TAT) induction and albumin secretion abilities were examined in rat hepatocytes immobilized within calcium alginate; the immobilized hepatocytes lost these abilities within a week. An attempt was then made to immobilize multicellular spheroids of hepatocytes for the purpose of stabilizing the liver functions. Although it takes at least 4 days to form spheroids in the conventional method using monolayer-cultured cells, in this study we developed a new method for rapid spheroid formation. Isolated hepatocytes were seeded into a polystyrene dish and incubated on a rotary shaker. Hepatocytes started to aggregate after 6 h of the rotation culture, and spheroids approximately 100 microns in diameter formed within 24 h. The immobilized spheroids had higher TAT induction and albumin secretion abilities, which were maintained for a longer time, than the immobilized nonaggregated cells. Further stabilization was observed in immobilized heterospheroids formed in the presence of nonparenchymal liver cells. This method for the rapid formation of spheroids consisting of hepatocytes and nonparenchymal liver cells could be utilized in the construction of a bioartificial liver support system.

Albumins↗
PubMed1993

Effects of nicardipine on the release of acetylcholine in the rat central nervous system.

Recent studies have indicated that specific dihydropyridine-sensitive Ca2+ channel binding sites are present in the brain, and that they play a crucial role in synaptic function. The present study was performed to determine the effects of nicardipine, a dihydropyridine-sensitive Ca2+ channel blocker, on the release of acetylcholine in the rat central nervous system. Striatal slices of rats which had been prelabelled with [3H]acetylcholine were superfused with Krebs-Ringer solution. The slices were stimulated with either electrical pulses (1 Hz) or an excitatory amino acid, L-glutamate, and the effects of nicardipine on the release of acetylcholine were examined. Electrical stimulation produced an increase in [3H]acetylcholine release from the striatal slices. Exposure of the slices to nicardipine significantly inhibited the stimulation-evoked [3H] acetylcholine release. An endogenous excitatory amino acid, L-glutamate, also elicited release of [3H]acetylcholine. Nicardipine significantly reduced the L-glutamate-induced release of [3H]acetylcholine, and the effect was pronounced in the presence of Mg2+. These results demonstrate that nicardipine inhibits both electrically and chemically stimulated [3H]acetylcholine release from rat striatum. The ability of nicardipine to inhibit cholinergic transmission may be related to the central effect of this Ca2+ channel blocker.

Acetylcholine↗
PubMed1993

Oral passive immunization effect of anti-human rotavirus IgY and its behavior against proteolytic enzymes.

The neutralization titer of anti-human rotavirus (HRV) IgY was completely inactivated by pepsin at pH 2.0. However, it was not significantly affected by trypsin or chymotrypsin under certain conditions. The immunological activity of the IgY was observed in the intestine of suckling mice for 2 h after oral administration and the activity rapidly decreased thereafter. The effects of oral supply of IgY were thus estimated for HRV-induced diarrhea in suckling mice and it was found that a previous supply of the IgY (1 h before HRV infection) completely prevented the HRV-induced diarrhea. The preventive effect was decreased as the time gap between IgY administration and HRV infection was longer. However, the oral supply of the IgY within 24 h after HRV infection was still effective and decreased the incidence of HRV diarrhea in suckling mice.

Administration, Oral↗