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Biomedical subjects

Y Hamada

Publications and source records attributed to Y Hamada.

At least 199 records · Page 11Linked to original sources
PubMed1998

The effect of cold cardioplegic cardiac arrest and electrically induced ventricular fibrillation on human cardiac beta-adrenoceptors during open-heart surgery.

This study was designed to test the hypothesis that distinct alterations in cardiac beta-adrenoceptors (betaARs) may occur during cardiopulmonary bypass (CPB) alone, during CPB with cold cardioplegic cardiac arrest (CCCA), and during CPB with electrically induced ventricular fibrillation (EIVF). We assessed the density and affinity of right atrial betaARs in 27 patients undergoing open-heart surgery by (-)-[125I]iodocyanopindolol binding before CPB, defined as the "control," immediately after initiation, defined as "before," and immediately before the cessation of CCCA or EIVF, defined as "after." The density of betaARs was equivalent between the "control" and "before" groups; however, during CPB with EIVF, the density of betaARs decreased significantly (P < 0.001), whereas during CPB with CCCA, it increased significantly (P < 0.01). The rate of changes of the betaAR density was not correlated with the "before"-"after" interval, and the affinity of the betaARs did not change throughout these CPBs. These findings demonstrate that: CPB alone does not affect cardiac betaARs, at least until the onset of EIVF or CCCA; CPB with EIVF induces rapid desensitization of cardiac betaARs; and CPB with CCCA induces rapid sensitization of cardiac betaARs.

Adolescent↗
PubMed1998

Supratentorial primitive neuroectodermal tumours: a report of four cases with an unusual clinical course in one patient.

Four children, who were treated for supratentorial primitive neuro-ectodermal tumours between 1986 and 1995 at Kyushu University Hospital, are here presented. The initial characteristic symptoms and signs of these patients included vomiting and headache, followed by motor weakness. All patients underwent direct surgery for their tumours while 2 also received a course of postoperative radio-therapy. After these treatments, 3 died within 4 months after diagnosis, whereas one infant, who underwent a total removal of the tumour but had no adjuvant therapy, is still alive after a follow-up period of 4 years. Most of the tumour cells of these 4 cases were poorly differentiated neuro-ectodermal cells, but some also showed variable differentiation along the glial and/or neuronal lines. While such differentiation had no impact on the clinical course of the patients, the malignant potential as assessed by the percentage of MIB1-positive cells showed a good correlation with the clinical features; the 3 cases with a rapid clinical course had MIB1 staining indices of more than 2%, and one case, who survived more than 4 years, had the same indices of 0.2% as found in benign tumours. Although "PNETs" of Hart and Earl share certain clinical features, they may be a group of tumours heterogeneous in their origins, histogenesis, and biological behaviours.

Biomarkers, Tumor↗
PubMed1998

Sequential percutaneous microwave coagulation therapy for liver tumor.

BACKGROUND: Percutaneous microwave coagulation therapy (PMCT) is effective for small liver tumors. To enhance the radicality of PMCT, we developed a sequential coagulation technique. METHODS: After inserting the first guide-needle under sonography, multiple needles were placed through a disk-type introducer that was devised to guide needle puncture at regular intervals, and microwaves were irradiated. Six patients, including 4 with hepatocellular carcinoma and 2 with liver metastasis, underwent this technique for tumors of 15 to 80 mm in diameter. RESULTS: This technique can coagulate an area up to 60 mm in diameter in one session. Insertion of multiple needles, ranging from 2 to 11, was successful without complications. Three patients undergoing curative PMCT developed no tumor recurrence. The other 3 received incomplete PMCT due to the large size and location of the tumor. CONCLUSIONS: This preliminary study indicates the efficacy of this technique to facilitate and secure PMCT in selected patients with liver tumors.

Carcinoma, Hepatocellular↗
PubMed1998

Enteric absorption of FK 506: estimation by a block liver perfusion technique in rats.

This perfusion model enables a pharmacokinetic study of enteral absorption and hepatic metabolic rate simultaneously. FK 506 is absorbed mainly via the proximal small intestine and metabolized rapidly by the liver during single passage. These results may lead to further analyses of absorption and metabolism of FK 506 under various conditions.

Animals↗
PubMed1998

Relationship between middle ear pressure, mucosal lesion, and mastoid pneumatization.

OBJECTIVES: The inflammatory changes of pneumatic space mucosa are thought to affect the development of pneumatic space and the function of transmucosal gas exchange. So, it is assumed that the mucosal change is deeply involved in the onset and healing process of otitis media with effusion (OME). The objective of this study is to investigate whether the growth of the mastoid cells and the middle ear transmucosal gas exchange function in patients with OME are affected by the histopathologic changes in middle ear mucosa, and whether these two factors are changed by the treatment of OME. MATERIALS AND METHODS: From 65 children with OME, middle ear mucosal specimens were collected during indwelling of a tympanic tube, and their histopathologic changes were compared with cell growth area measured on radiographic films and with the change in the middle ear total pressure (METP). RESULTS: Suppression of the cell growth area was stronger and the METP stayed lower in cases with a higher degree of mucosal lesion. Significant expansion of pneumatic area was observed after 2 years of tube indwelling, and the peak METP showed a significant increase after 1.5 years. This increase in the METP was caused by diffusion/absorption of CO2 and O2 and indicated recovery of the transmucosal gas exchange function. CONCLUSIONS: The growth of the mastoid cells and the middle ear transmucosal gas exchange function are closely affected by the subepithelial histopathologic changes in middle ear mucosa, and these two factors recover by the treatment of OME.

Adolescent↗
PubMed1998

Induction of Leydig cell tumors by lacidipine via up-regulation of the LHRH receptor on Leydig cells in rats.

Long-term (78 weeks) administration of lacidipine, a dihydropyridine calcium antagonist, increased the incidence of Leydig cell tumors (LCTs) in Sprague-Dawley rats. Lacidipine also increased and decreased the plasma luteinizing hormone (LH) and testosterone levels, respectively. Leydig cells from lacidipine-treated rats showed increases in luteinizing hormone-releasing hormone (LHRH) receptor expression, protein kinase C (PKC) activity, expression of proto-oncogenes, and 5-bromodeoxyridine uptake; whereas their calcium level, LH receptors, and testosterone content decreased. These data suggest that LHRH receptors play an important role in the development of rat LCTs induced by lacidipine, which activates a cascade of cell cycle-regulatory genes via PKC. When isolated Leydig cells were cultured with lacidipine or nicardipine, these changes in rat Leydig cells were not demonstrable in mice and monkeys, species having many fewer testicular LHRH receptors than rats. Thus, lacidipine may pharmacologically induce LCTs in rats but not in mice, with the difference depending on the presence or absence of testicular LHRH receptors. The induction of LCTs by lacidipine in rats is unlikely to occur in humans, since their Leydig cells lack LHRH receptors.

Administration, Oral↗
PubMed1998

Influence of interindividual variability of aldose reductase protein content on polyol-pathway metabolites and redox state in erythrocytes in diabetic patients.

OBJECTIVE: To clarify the influence of interindividual difference in the level of aldose reductase on the polyol pathway-related metabolism in diabetic patients. RESEARCH DESIGN AND METHODS: The enzyme protein content was determined by a two-site enzyme-linked immunosorbent assay using monoclonal and polyclonal antibodies to recombinant human aldose reductase in erythrocytes from 35 diabetic patients and 11 healthy volunteers. Patients were stratified into two groups by the median of aldose reductase content, and the erythrocyte sorbitol level, the fructose level, and the lactate-to-pyruvate ratio were compared between the two groups. We also examined the correlation of the enzyme content with these metabolic parameters. RESULTS: The group of patients whose enzyme content was above the median showed a significant increase in the levels of sorbitol (34.7 +/- 4.9 vs. 20.4 +/- 2.0 nmol/g Hb, P < 0.05) and fructose (99.8 +/- 17.2 vs. 45.9 +/- 4.6 nmol/g Hb, P < 0.05), along with an elevated lactate-to-pyruvate ratio (28.6 +/- 6.1 vs. 11.7 +/- 1.2, P < 0.05), compared with patients with low enzyme levels. The aldose reductase content in erythrocytes was well correlated with its activity, and there was a significant correlation between the enzyme content and the erythrocyte sorbitol (r = 0.58, P < 0.001) or fructose (r = 0.57, P < 0.001) levels as well as between the enzyme level and the lactate-to-pyruvate ratio (r = 0.38, P < 0.05). CONCLUSIONS: These results suggest that the interindividual variability of aldose reductase content may contribute tangibly to the polyol-pathway flux and cytoplasmic redox alteration in diabetic patients.

Aldehyde Reductase↗
PubMed1998

Asp905Tyr polymorphism of the gene for the skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 in NIDDM.

OBJECTIVE: To clarify the contribution of the Asp905Tyr polymorphism of the muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PP1G) to insulin resistance and related diseases. RESEARCH DESIGN AND METHODS: We investigated the Asp905Tyr polymorphism of the PPP1R3 gene, which encodes the muscle-specific glycogen-targeting subunit of PP1G, in 259 Japanese patients with NIDDM and 194 healthy control subjects. RESULTS: No significant difference was found in the genotype distribution between NIDDM patients (N = 259; Asp/Asp = 0.10, Asp/Tyr = 0.44, Tyr/Try = 0.46) and healthy control subjects (n = 194; Asp/Asp = 0.13, Asp/Tyr = 0.37, Tyr/Tyr = 0.50) or between patient groups subdivided by the mode of treatment: NIDDM patients with insulin therapy (Asp/Asp = 0.14, Asp/Tyr = 0.46, Tyr/Tyr = 0.40) and those without insulin therapy (Asp/Asp = 0.07, Asp/Tyr = 0.43, Tyr/Tyr = 0.50). However, NIDDM patients with the Tyr allele, which was previously reported to be associated with insulin resistance, tended to have lower BMIs than those without this allele (Asp/Asp: 24.5 +/- 1.1 kg/m2, Asp/Tyr: 22.6 +/- 0.4 kg/m2, Tyr/Tyr: 22.8 + 0.3 kg/m2, P = 0.06 by analysis of variance). CONCLUSIONS: These data suggest that the Asp905Tyr polymorphism of the PPP1R3 gene is not associated with NIDDM or high BMI, both of which are known to be insulin-resistant states, in the Japanese population.

Adult↗
PubMed1998

Participation of nitric oxide in the mucosal injury of rat intestine induced by ischemia-reperfusion.

The dual role of nitric oxide as a cytoprotective or a cytotoxic free radical gas has been noted in various types of pathophysiological conditions, including the digestive system. The aim of this study was to examine the role of nitric oxide in the mucosal injury induced by ischemia-reperfusion in the rat small intestine. A transient intestinal ischemia was produced in the catheterized ileal segments of rats by occluding the anterior mesenteric artery for 60 min. Nitric oxide metabolites (NO2- and NO3-) and lactate dehydrogenase activity in perfusates of the intestinal lumen were measured over 5 hr periods. The time-course of histological changes in small intestine was also observed. After ischemia-reperfusion, nitric oxide release in the intestinal lumen increased significantly and the dynamics of nitric oxide release correlated with that of lactate dehydrogenase leakage. The administration of NG-nitro-L-arginine methyl ester (1.0-2.5 mg/kg) inhibited this increased nitric oxide release and the lactate dehydrogenase leakage and afforded protection against the mucosal injury induced by ischemia-reperfusion. In conclusion, the nitric oxide production that was accelerated by ischemia-reperfusion of small intestine may possibly participate in the breakdown of intestinal mucosa after ischemia-reperfusion insult.

Animals↗
PubMed1998

[Eleven cases of paroxysmal kinesigenic choreoathetosis; correlation with benign infantile convulsions].

We report 11 subjects, consisting of sibling cases from 5 unrelated families, with paroxysmal kinesigenic choreoathetosis (PKC). In these subjects the PKC attacks started between the ages of 5 and 17 years and were well controlled with anti-epileptic drugs or subsided spontaneously. In 8 cases from 4 families with PKC, infantile convulsions occurred between the ages of 3 and 8 months and an excellent prognosis was obtained in all but one male. Four of the 8 subjects had complex partial seizures which were characterized by staring, eye deviation, apnea, or loss of consciousness. The nature of these convulsions shared some of the clinical features of benign infantile epilepsies, which have been recently advocated as a new category of epilepsy. There were no differences in the clinical between the cases with and without infantile convulsions.

Adolescent↗
PubMed1998

Polyol pathway hyperactivity is closely related to carnitine deficiency in the pathogenesis of diabetic neuropathy of streptozotocin-diabetic rats.

To investigate the relationship between polyol pathway hyperactivity and altered carnitine metabolism in the pathogenesis of diabetic neuropathy, the effects of an aldose reductase inhibitor, [5-(3-thienyl) tetrazol-1-yl]acetic acid (TAT), and a carnitine analog, acetyl-L-carnitine (ALC), on neural functions and biochemistry and hemodynamic factors were compared in streptozotocin-diabetic rats. Significantly delayed motor nerve conduction velocity, decreased R-R interval variation, reduced sciatic nerve blood flow and decreased erythrocyte 2, 3-diphosphoglycerate concentrations in diabetic rats were all ameliorated by treatment with TAT (administered with rat chow containing 0.05% TAT, approximately 50 mg/kg/day) or ALC (by gavage, 300 mg/kg/day) for 4 weeks. Platelet hyperaggregation activity in diabetic rats was diminished by TAT but not by ALC. TAT decreased sorbitol accumulation and prevented not only myo-inositol depletion but also free-carnitine deficiency in diabetic nerves. On the other hand, ALC also increased the myo-inositol as well as the free-carnitine content without affecting the sorbitol content. These observations suggest that there is a close relationship between increased polyol pathway activity and carnitine deficiency in the development of diabetic neuropathy and that an aldose reductase inhibitor, TAT, and a carnitine analog, ALC, have therapeutic potential for the treatment of diabetic neuropathy.

Acetylcarnitine↗
PubMed1997

Effect of an aldose reductase inhibitor on abnormalities of electroretinogram and vascular factors in diabetic rats.

The effect of an aldose reductase inhibitor, [5-(3-thienyl) tetrazol-1-yl] acetic acid (TAT), on the electroretinogram was determined in rats with streptozotocin-induced diabetes. Laboratory chow containing 0.05% TAT was given to rats for 2 months, while other diabetic rats were untreated. Groups of TAT-treated and untreated normal rats were also studied. Treatment with TAT produced significant improvement of the electroretinogram. TAT shortened the peak latencies of the b-wave oscillatory potentials, which were significantly prolonged in untreated diabetic rats (P < 0.0001 vs. untreated normal rats). This was accompanied by a significant decrease in the retinal sorbitol and fructose concentrations (by 46.5% and 25.7%, respectively). TAT treatment of diabetic rats also markedly reduced ADP-induced platelet aggregation and significantly increased the red blood cell 2,3-diphosphoglycerate level, accompanied by a marked reduction in sorbitol and fructose concentrations of platelet and red blood cells. There were significant correlations between the summed b-wave peak latencies and platelet aggregation or the 2,3-diphosphoglycerate level in diabetic rats. These findings suggest that an aldose reductase inhibitor, TAT, has therapeutic value for diabetic retinopathy.

2,3-Diphosphoglycerate↗
PubMed1997

Insulin gene region contributes to genetic susceptibility to, but may not to low incidence of, insulin-dependent diabetes mellitus in Japanese.

In the Caucasian population, it has been demonstrated that the insulin gene (INS) region contains the insulin-dependent diabetes mellitus locus (IDDM2). In the Japanese population, however, there has been no report demonstrating the contribution of IDDM2 to the pathogenesis of IDDM. We conducted an association study of IDDM in a large number of Japanese subjects with multiple polymorphisms in INS region. We found a significant association of the INS region with IDDM. Alleles positively associated with IDDM in INS region were the same as those positively-associated with IDDM in Caucasian population, although positively-associated alleles are very common (allele frequencies > 0.9) in the Japanese general population. These data suggest that IDDM2 is involved in the genetic susceptibility to IDDM in Japanese. The high frequencies of disease-associated alleles in the general population suggest that IDDM2 locus is not responsible for the low incidence of IDDM in Japanese.

DNA, Satellite↗
PubMed1997

Pyloroduodenal duplication cyst: case report

A 6-day-old female presented with vomiting and an abdominal mass. At laparotomy, a pyloroduodenal duplication cyst was enucleated from the pyloric region. Of the diagnostic studies performed, IV cholangiography with spiral computed tomography and an upper gastrointestinal barium study were useful in the preoperative differential diagnosis.

Journal Article↗