Biomedical subjects

Y Hamada

Publications and source records attributed to Y Hamada.

At least 181 records · Page 10Linked to original sources

PubMed1999

Notch2 expression negatively correlates with glial differentiation in the postnatal mouse brain.

Notch family molecules are thought to be negative regulators of neuronal differentiation in early brain development. After expression in the embryonic period, Notch2 continues to be expressed postnatally in the specific regions in the rodent brain. Here, we examined Notch2 expression in the postnatal mouse brain using lacZ knockin animals at the Notch2 locus. Notch2 expression was observed in the developing cerebellum and hippocampus, characteristic regions where neurogenesis persists after birth. Double staining of sections revealed that Notch2 was expressed by Bergmann glia in the cerebellum, radial glia in the hippocampus, and some astrocytes in both regions. Notch2 expression by glial cells was clearly confirmed in dissociated cell cultures. Interestingly, neocortical glia, many of which did not express Notch2 in vivo, did express Notch2 in a dissociated culture condition. The triple staining of dissociated cell cultures revealed that stronger Notch2 expression correlated with the immature type of glial gene expressions: stronger vimentin and weaker glial fibrillary acidic protein expressions. In addition, Notch2 expression correlated with the incorporation of bromodeoxyuridine both in vivo and in vitro. Thus, these findings demonstrate that Notch2 is expressed not only by neuronal cells in the embryonic brain, but also by glial cells in the postnatal brain, and that its expression negatively correlates with glial differentiation, proposing its novel function as a negative regulator of glial differentiation in mammalian brain development.

Aging↗

PubMed1999

Extended thymectomy for myasthenia gravis in an octogenarian. A case report.

An 86-year-old woman with myasthenia gravis successfully underwent an extended thymectomy. The patient had a 2-year history of generalized myasthenia and had limited response to anticholinesterases and steroids. An extended thymectomy was successfully performed in the usual fashion. The postoperative course was uneventful except for an episode of psychosis probably due to postoperative steroid therapy. The steroid dosage was gradually reduced to 5 mg/day over seven months after the operation, during which she became fully asymptomatic. No symptoms due to myasthenia have surfaced for over 2 years after surgery. Although elderly patients are usually considered to be less responsive to an operation, thymectomy may sometimes be the treatment of choice for myasthenia gravis even in octogenarians.

Aged↗

PubMed1999

Sodium/hydrogen ion exchange inhibitor ameliorates ischaemia-reperfusion injuries in the rat hind limb.

PURPOSE: This study was designed to investigate the effect of a newly synthesised sodium/hydrogen ion exchange inhibitor, SM-20550, on ischaemia-reperfusion induced injury in a rat hind limb model. METHODS: In order to induce ischaemia of the hind limbs, the abdominal aorta just distal to the renal arteries and the bilateral femoral arteries were clamped. Nineteen rats were divided into three groups. In the sham group (n=5), the vessels were only dissected and a vehicle solution was administered. In the control group (n=7), the vessels were clamped for five hours, and a vehicle solution was administered 10 minutes prior to clamping and continued for five hours after reperfusion. In the SM group (n=7), clamping was maintained for five hours with a bolus injection of SM-20550 and continuous infusion of the solution for five hours after reperfusion. Water content of the left gastrocnemius muscle was calculated. The right gastrocnemius was fixed in 10% formalin. A transverse thin section was stained with antimyoglobin antibody. Stained cells of the right gastrocnemius were counted and the myoglobin staining index was calculated. RESULTS: Water content was significantly (p<0.002) lower in the SM group than in the control group. The myoglobin staining index was significantly (p<0.01) higher in the SM group than in the control group. There was no significant difference between the control and the SM groups in creatinine phosphokinase (CPK) and lactate dehydrogenase (LDH). CONCLUSIONS: Our results indicate that the sodium/hydrogen ion exchange inhibitor, SM-20550, ameliorates oedema formation and ischaemia-reperfusion induced injury of the skeletal muscle.

Amidines↗

PubMed1999

N-acetyl-beta-D-glucosaminidase is not a predictor, but an indicator of kidney injury in patients with cardiac surgery.

The urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) was evaluated in terms of its ability to predict renal failure following open-heart surgery. Twenty-two patients were divided into three groups; 6 patients with post-operative renal failure (RF group), 9 without renal failure (non-RF group) and 7 who underwent non-cardiac surgery (non-ECC group). NAG levels during operation were significantly higher in the non-RF group than in the non-ECC group (2.28 +/- 0.50 U vs. 0.39 +/- 0.06 U, p < 0.01). NAG levels in the RF group were not significantly different from those in the non-ECC group (1.12 +/- 0.28 U/hr vs. 0.39 +/- 0.06 U/hr, p > 0.1), and in the non-RF group (1.12 +/- 0.28 U/hr vs. 2.28 +/- 0.50 U/hr, p > 0.1). Post-operative NAG levels were not significantly different between the RF and non-RF groups, whereas post-operative creatinine clearance values were significantly different (on 2, 6 and 7 post-operative day, p < 0.05). Our data suggest that the kidney is predisposed to renal failure by cardiopulmonary bypass and the chance of renal failure depends in some part on post-operative patient management.

Acetylglucosaminidase↗

PubMed1998

Effects of dienogest (a synthetic steroid) on coagulation, fibrinolysis, and platelet aggregation in female monkeys.

We investigated the effects of dienogest (0.1-10 mg/kg per day, p.o.) on coagulation, fibrinolysis and platelet aggregation in female rhesus monkeys. Then, we also examined those of medroxyprogesterone acetate (MPA, 10 mg/kg per day, p.o.) or danazol (10-1000 mg/kg per day, p.o.) on these parameters in the same species. In addition, we assessed the effects of dienogest (1 and 3 mg/kg per day, p.o.) or MPA (10 mg/kg per day, p.o.) on platelet aggregation and platelet lipids in female cynomolgus monkeys. At doses of 0.3 mg/kg or greater, dienogest increased the levels of several coagulation and anticoagulation factors, but had no effect on the prothrombin time, activated partial thromboplastin time, fibrinolysis, or platelet aggregation. MPA (10 mg/kg) had no effect on coagulation or fibrinolysis, but significantly potentiated platelet aggregation in response to ADP and collagen and also increased the platelet cholesterol-to-phospholipid ratio. Danazol (10 mg/kg or more) increased the activities of coagulation factors V, VII, VIII, X, XI, and XII in comparison to dienogest and MPA. Consequently, dienogest caused less potentiation of platelet aggregation than MPA and less potentiation of coagulation than danazol.

Animals↗

PubMed1998

Medium change amplifies mitogen-activated protein kinase-mediated prostaglandin E2 synthesis in Swiss 3T3 fibroblasts.

In Swiss 3T3 fibroblasts, changing the culture medium prior to stimulation resulted in an augmentation of bradykinin-induced prostaglandin E2 synthesis. The augmentation depended on the duration of the exposure to the fresh medium, with a maximum effect at 1 h. Fetal calf serum in the fresh medium was essential for augmented prostaglandin E2 synthesis. The medium change slightly augmented the bradykinin-induced increase in intracellular free Ca2+ concentration and phosphoinositide hydrolysis with a different time course from that for prostaglandin E2 synthesis. 4',5,7-Trihydroxyisoflavone (genistein) and 3,4-dihydroxybenzylidene-malononitrile (tyrphostin 23), inhibitors of tyrosine kinases, and 2'-amino-3'-methoxyflavone (PD98059), an inhibitor of mitogen-activated protein kinase (MAPK) kinase, attenuated the increase in prostaglandin E2 synthesis. Bradykinin caused phosphorylation of cytosolic phospholipase A2 and p42/p44 MAPK, which was augmented by the medium change. From the results, it is concluded that activation of MAPK and cytosolic phospholipase A2 is involved in the augmentation of prostaglandin E2 synthesis produced by the medium change.

3T3 Cells↗

PubMed1998

GLUT1 glucose transporter: differential gene transcription and mRNA binding to cytosolic and polysome proteins in brain and peripheral tissues.

The ratio of GLUT1 mRNA to actin mRNA in brain was 6- to 13- fold greater than the corresponding ratio in spleen, lung, testis, heart, and skeletal muscle in the rat. However, the ratio of GLUT1 transcription rate to actin transcription rate is comparable in brain and the five other organs. Organ extracts were fractionated into cytosol and polysomes, and ultraviolet light cross-linking studies were performed with these proteins and 32P-labeled GLUT1 mRNA containing the 3'-untranslated region (UTR) generated from transcription plasmids. The cytosol of brain, lung, spleen, C6 glioma cells in tissue culture, and freshly isolated bovine brain capillaries express a pair of 95 kDa and 74 kDa proteins, designated collectively as p88, and the polysome fraction of brain, testis, or C6 glioma cells express a 44-kDa protein, designated p44. In a middle cerebral artery occlusion model, brain cytosol p88 was up-regulated and p44 was down-regulated. These findings are consistent with the hypothesis that GLUT1 gene expression is subject to regulation at the post-transcriptional level.

Animals↗

PubMed1998

In vivo formation of a Schiff base of aminoguanidine with pyridoxal phosphate.

Aminoguanidine (AG) is considered to be a promising compound for the treatment of diabetic complications. We examined the in vitro and in vivo formation of Schiff bases of AG with pyridoxal 5'-phosphate (PLP) and pyridoxal (PL). AG reacted in vitro far more rapidly with PLP to form a Schiff base (PLP-AG) than with PL to form another Schiff base (PL-AG). Administration of AG at 7 mM in drinking water for 18 weeks caused the formation of PLP-AG in the liver and kidney of mice (12.1 +/- 1.6 and 3.8 +/- 0.64 nmol/g of tissue, respectively, mean +/- SD, N = 6). The amount of PLP in the liver of mice AG administered was significantly lower than that of control mice (4.0 +/- 1.4 vs 17.4 +/- 1.3 nmol/g of wet tissue, mean +/- SD, N = 6). Simultaneous administration of pyridoxine (1 mM in drinking water) with AG (7 mM in drinking water) did not ameliorate the decrease in tissue PLP and caused the excess formation of PLP-AG. The results suggest that attention should be paid to the deficiency of tissue PLP in the clinical use of AG.

Animals↗

PubMed1998

CD45RChighCD4+ intestinal mucosal lymphocytes infiltrating in the inflamed colonic mucosa of a novel rat colitis model induced by TNB immunization.

To clarify the role of CD4(+) intestinal mucosal lymphocytes in chronic intestinal inflammation, we developed a new rat colitis model by immunization with 2,4,6-trinitrobenzenesulfonic acid (TNB) in an emulsion with an adjuvant followed by transrectal administration of a low dose of TNB. Moreover, we assessed the therapeutic effect of anti-CD4 monoclonal antibody (mAb) on this model. In concert with the development ofserum anti-TNB Abs, transmural and segmental colitis that mimics some characteristics of human Crohn's disease was induced in the immunized rats. Immunohistochemical analysis showed the increase of infiltrating lamina propria CD4(+) T cells. Flow-cytometric analysis of isolated cells from inflamed mucosa revealed that CD45RChighCD4(+) T cells were significantly increased. Interestingly, intraperitoneal administration of anti-CD4 mAbs could suppress severe inflammation in the model with decrease of anti-TNB Ab titer. After the treatment with anti-CD4 mAbs, CD45RChighCD4(+) T cells in the lamina propria and interferon-gamma mRNA expression in the colonic lamina propria CD4(+) T cells were decreased. These results indicated that Th1 CD4(+) intestinal mucosal T cells have a role in the progress of inflamed lesions in chronic enteritis. They implicate that a therapy targeting mucosal T cells expressing CD4 may be feasible in the treatment of human Crohn's disease.

Animals↗

PubMed1998

Epidermal growth factor stimulates the recovery of glucose absorption after small bowel transplantation.

Epidermal growth factor (EGF) has been reported to enhance adaptation in damaged intestines following massive intestinal resection. Studies were performed to determine whether EGF influences the recovery of intestinal function after small bowel transplantation in rats. Recipient Lewis rats underwent resection of the distal 80% of the small bowel, which was replaced with a 20-cm isograft. EGF (30 microg/kg/day) or its vehicle (control) was infused intraperitoneally for 3 days after transplantation. After 7 days, the graft was isolated for morphologic studies and was used for analysis of glucose and water absorption and the expression of sodium glucose cotransporter (SGLT1). These were used as indicators of functional adaptation. The EGF-treated group exhibited significantly increased mucosal villous height, crypt cell proliferation, glucose and water absorption, and expression of SGLT1 protein compared to the control group. No significant differences were found in body weight change or crypt depth between the two groups. These results demonstrate that EGF augments structural and functional adaptation of intestinal grafts in rats. EGF may be useful after intestinal transplantation in patients with short bowel syndrome.

Animals↗

PubMed1998

Accumulation of class I mutant p53 and apoptosis induced by carboplatin in a human glioma cell line.

Following DNA damage, wild-type p53 increases and mediates the multiple cellular responses for the repair of DNA damage or apoptosis. Inactivation of p53 by single-amino-acid substitutions contributes to the malignant phenotype and confers resistance to therapy. Among tumor-derived p53 mutants, class I mutants still retain a native-like three-dimensional structure, whereas class II mutants have unfolded DNA-binding domains. Sequencing analysis demonstrated that a human glioma cell line (U-373MG) had only a class I mutant form of p53 of His273, which targets an Arg273 that contacts DNA but retains the native structure. In this study, we investigated the metabolic alteration of the class I mutant p53 in apoptosis of U-373MG. The cell cycle progression of U-373MG cells was affected by the addition of carboplatin, while the amount of mutant p53 also increased in their nuclei. The treated cells underwent apoptosis 48h after exposure to 50 microg/ml carboplatin. Although the exact mechanism of the class I mutant p53 in the process of apoptosis has not yet been clarified, the fact that accumulation of the activated mutant p53 in the nucleus of U-373MG is concomitant with apoptosis, just as wild-type p53 does, implies that the class I mutant p53 might retain the ability to participate in apoptosis.

Antigens, Nuclear↗

PubMed1998

Meta-analysis of association of insertion/deletion polymorphism of angiotensin I-converting enzyme gene with diabetic nephropathy and retinopathy.

An insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene has repeatedly been shown to be associated with ischaemic heart disease, but the association of this genetic marker with diabetic microangiopathy is controversial. To assess the association of the genotypes with the development of diabetic nephropathy or retinopathy, we performed a meta-analysis of data from the literature, using Mantel-Haenszel method followed by the Breslow-Day test for assessing homogeneity among data. In a total of 4773 diabetic patients from 18 studies with (n = 2495) and without (n = 2278) renal complications, the D allele was significantly associated with diabetic nephropathy (p < 0.0001) in a dominant model (summary odds ratio 1.32, 95% confidence interval: 1.15 to 1.51). There was no significant evidence against homogeneity of the odds ratios (chi(2) = 18.9, 20 df; p = 0.53). The association was significant both in non-insulin-dependent (p < 0.005) and in insulin-dependent diabetes mellitus (p < 0.05). Likewise, in a total of 2010 diabetic patients with (n = 1008) and without (n = 1002) retinopathy, there was no association of the I/D polymorphism with diabetic retinopathy. These data suggest that the ACE I/D polymorphism affects the risk for diabetic nephropathy, but not for diabetic retinopathy.

Alleles↗

PubMed1998

Association of distal chromosome 2q with IDDM in Japanese subjects.

An insulin-dependent diabetes mellitus (IDDM)-susceptibility gene (IDDM13) has recently been mapped to a region of distal chromosome 2q, which is syntenic to the region of mouse chromosome 1 containing a murine susceptibility gene for IDDM, Idd5. To determine the contribution of this region to IDDM disease susceptibility further and to narrow the region for positional cloning of susceptibility genes, we have studied the association of distal chromosome 2q with IDDM in the genetically distinct Japanese population. A 137 mobility unit (mu) allele at D2S137 locus was significantly associated with IDDM (odds ratio 1.92, p = 0.0016). Other markers, D2S301 and D2S143, located in the same region were not associated with IDDM, indicating that IDDM13 is in linkage disequilibrium with D2S137, but not with D2S301 or D2S143. The association of D2S137 with IDDM was observed in patients lacking one of two high risk HLA alleles, DQBI*0303 and DQBI*0401, but not in patients with either of these alleles. The frequency of high risk HLA alleles was significantly lower in patients with the susceptible allele at D2S137, suggesting that IDDMI3 contributes to IDDM susceptibility in subjects without high risk genotypes at IDDM1. Demonstration of allelic association of D2S137 with IDDM localizes IDDM13 in the close vicinity (<2 centiMorgans) of D2S137, greatly facilitating fine structure mapping and positional cloning of IDDM13.

Adolescent↗

PubMed1998

Rapid enlargement of a choledochal cyst: antenatal diagnosis and delayed primary excision.

A case of choledochal cyst (CC) antenatally diagnosed at 29 weeks' gestation is reported. Rapid enlargement of the cyst soon after delivery resulted in complete gastric outlet obstruction (GOO). The lesion was treated by external drainage as a temporary maneuver, with delayed cyst excision and hepaticoduodenostomy at the hepatic hilum performed at 81 days of age. Surgical treatment of CC in early infancy has been reported to be safe and effective. However, delayed primary excision would be an alternative procedure, especially in rare cases showing rapid enlargement resulting in GOO, since this choice has the potential advantage of allowing weight gain and improved nutritional status without risking interim complications due to the drainage procedure.

Adult↗

PubMed1998

Spiral computed tomography for bilioenteric anastomotic stricture.

Spiral computed tomography scanning after intravenous cholangiography (IVC-SCT) was used to assess the anatomy of the biliary tree and anastomosis in a 7-year-old girl with recurrent cholangitis 5 years after surgical excision of a choledochal cyst. The technique clearly visualized the stenosis of the hepaticojejunostomy and hepatic duct and the dilated intrahepatic ducts. IVC-SCT provides a precise, prompt, and accurate image with minimal invasiveness and is especially suitable for the preoperative evaluation of pediatric patients.

Anastomosis, Surgical↗

PubMed1998

Cystic lymphangioma of the scrotum.

A 7-year-old boy who presented with a painful left hemiscrotal mass was diagnosed with acquired lymphangioma of the scrotum. Chronic friction from a cast for Perthes' disease might have been the cause of sudden enlargement of a congenital lymphangioma of the scrotum. Magnetic resonance imaging (MRI) was useful for preoperative diagnosis and determining the extent of the scrotal lesions. Total excision of the mass leaving the overlying skin was successfully performed. The clinical significance of MRI for preoperative diagnosis and planning surgical resection of this lesion is discussed.

Child↗

PubMed1998

Hepatocyte nuclear factor-1alpha gene and non-insulin-dependent diabetes mellitus in the Japanese population.

Recently, hepatocyte nuclear factor-1alpha(HNF-1alpha, which is encoded by the TCF1 gene) mutations were reported in a subset of patients with maturity onset diabetes of the young (MODY3). We studied the contribution of TCF1 to genetic susceptibility to common non-insulin-dependent diabetes mellitus (type 2) in Japanese subjects by investigating allelic association with type 2 diabetes use of three markers. We also studied the frequency of the G191D mutation, the only mutation of TCF1 reported so far in late-onset type 2 diabetes. A total of 356 subjects were studied. There were no significant differences in allele frequency of the three markers between patients with type 2 diabetes and control subjects. A G191D mutation was not found in the subjects studied, giving a frequency of less than 0.4% in common type 2 diabetes. The lack of association of type 2 diabetes with three markers in and near TCF1 suggests that mutations in TCF1 derived from a limited number of founders are not a major cause of common type 2 diabetes even in the genetically homogeneous Japanese population. The data also indicate that the G191D mutation in TCF1 plays little, if any, role in susceptibility to common type 2 diabetes in the Japanese.

Adult↗

PubMed1998

Ovarian teratoma with gliomatosis peritonei: report of two cases.

Gliomatosis peritonei, a rare condition related to ovarian teratomas, involves the peritoneal implantation of numerous nodules of predominantly mature glial tissues. We report herein the cases of two patients with immature ovarian teratoma associated with gliomatosis peritonei, in one of whom a rapid progression of teratomatous implants occurred 14 weeks after her initial surgery. Gliomatosis peritonei is considered benign in most cases; however, some reports have documented the rapid recurrence of immature peritoneal implants, as implantation is associated with teratomas of all grades. Thus, in the face of peritoneal implants suspected to be of a teratomatous nature, thorough and extensive sampling is essential to exclude the presence of immature elements which may imply a poor prognosis and require aggressive therapy.

Ascitic Fluid↗