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Biomedical subjects

M Shibata

Publications and source records attributed to M Shibata.

At least 73 records · Page 4Linked to original sources
PubMed2001

Circulating factor VIII immune complexes in patients with type 2 acquired hemophilia A and protection from activated protein C-mediated proteolysis.

Factor VIII (FVIII) inhibitor antibodies are classified into 2 groups according to the kinetic pattern of FVIII inactivation. Type 2 antibodies are more commonly observed in patients with acquired hemophilia A and do not completely inhibit FVIII activity; in most cases, substantial levels of circulating FVIII are detected. Three type 2 autoantibodies from patients who had normal levels of FVIII antigen despite having low levels of FVIII activity were studied. The antibodies reacted exclusively with the light chain of FVIII but not with the C2 domain, and their epitopes were therefore ascribed to the regions in the A3-C1 domains. Heavy and light chains of FVIII were detected in plasma-derived immune complexes extracted by using protein G Sepharose. Direct binding assays using anhydro-activated protein C (anhydro-APC), a catalytically inactive derivative of activated protein C (APC) in which the active-site serine is converted to dehydroalanine, were used to examine the relation between immune complexes and APC. The intact FVIII, 80-kd light chain, and 72-kd light chain bound in a dose-dependent manner to anhydro-APC, with K(d) values of 580, 540, and 310 nM, respectively, whereas no appreciable binding was detected for the heavy chain. The 3 autoantibodies blocked FVIII binding to anhydro-APC by approximately 80% and consequently inhibited APC-induced FVIII proteolytic inactivation. These antibodies also bound to a synthetic peptide, His2009-Val2018, which contains the APC binding site. The findings suggest that binding of type 2 autoantibodies, recognizing residues His2009 to Val2018, protects FVIII from APC-mediated proteolysis and might contribute to the presence of FVIII immune complexes in the circulation.

Antigen-Antibody Complex↗
PubMed2001

Toxicity of theophylline depends on plasma concentration by single and also repeated dosing in rats.

The purpose of this study was to evaluate the relationship between the in vivo toxicity and plasma concentration of theophylline. Theophylline was administered intravenously in single doses ( 50, 100, 150 and 200 mg kg(-1)once a day) or repeated doses (12.5, 25 and 90 mg kg(-1)/day for 28 days) in rats. Plasma concentrations of theophylline increased dose-dependently in both single and repeated doses, and there were no differences due to effects of 28-times repeated administration. Neither single dose at 50 mg kg(-1)nor repeated dose at 12.5 mg kg(-1)/day injections of theophylline showed toxic signs, in which plasma concentrations of theophylline were less than 110 and 22.5 microg ml(-1), respectively. Theophylline induced myocardial fibrosis in 25 mg kg(-1)/day and more treated groups: in which plasma concentrations of theophylline were more than 50 microg ml(-1). At doses of 100 mg kg(-1)(single) and 90 mg kg(-1)/day (repeated), theophylline caused tachypnea and excitement of movement. Each theophylline concentration in plasma was more than 194 microg ml(-1)in single 100 mg kg(-1)and 162 microg ml(-1)in repeated 90 mg kg(-1)/day injections, respectively. Death was observed at a dose of 200 mg kg(-1), in which the plasma concentration of theophylline was more than 264 microg ml(-1). Moreover, the recovery period from signs of toxic poisoning to normality in the 200 mg kg(-1)treated group was greater than that in the 150 mg kg(-1)and less treated groups. The results indicated that the in vivo toxicity of theophylline is highly dependent on plasma concentrations in rats which received single and also repeated doses of theophylline.

Animals↗
PubMed2001

Combined hepatocellular carcinoma and cholangiocarcinoma growing into the common bile duct.

We report a patient with combined hepatocellular carcinoma and cholangiocarcinoma (HCC-CC) growing into the common bile duct (CBD) and showing obstructive jaundice within 2 years of the onset of the disease. The patient was a 59-year-old Japanese man in whom, at the age of 57 years. a hepatic tumor was discovered by diagnostic imaging during follow-up of hepatitis B surface antigen (HBsAg)-positive liver cirrhosis. The tumor was diagnosed as HCC. Epirubicin was injected twice, intraarterially. The patient then received oral etoposide therapy for the next 14 months. The treatment was initially effective, but approximately 2 years after the hepatic tumor was discovered, local recurrence of the tumor and a tumor thrombus in the CBD were discovered. Although he was treated with percutaneous transhepatic biliary drainage (PTBD), to reduce obstructive jaundice, the jaundice was irreversible and he died of severe hepatic failure. The autopsy findings confirmed that the hepatic tumor was HCC-CC, in which the HCC and CC components expressed alpha-fetoprotein (AFP) and carbohydrate antigen 19-9 (CA19-9), respectively, which accurately reflected the disease process. The underlying mechanism of the growth of HCC-CC into the CBD may differ from the underlying mechanism of the development of icteric-type HCC.

Bile Ducts, Intrahepatic↗
PubMed2001

Pupillary abnormality on admission and brain bulging during surgery as unfavourable predictors in patients treated with hypothermia: a retrospective review of 81 patients with severe head injury.

BACKGROUND: To determine factors predicting outcome of patients with severe head injury, the authors retrospectively analyzed 81 patients, 3 to 70 years of age, who were treated by hypothermia. METHOD: The initial Glasgow Coma Scale scores of the 81 patients ranged from 3 to 8. Outcome in each case was determined at six months after injury and was retrospectively analyzed with respect to patient characteristics, initial clinical status, laboratory data, computed tomographic findings, data from monitoring, intra-operative findings, and treatment methods. The significance of clinical and neuroradiological factors for predicting unfavorable outcome was analyzed by univariate logistic regression. Stepwise multiple logistic regression analysis was then used to identify independent predictors of outcome. FINDINGS: Favorable outcome was observed in 27 of 81 patients treated by hypothermia. Independent factors predicting unfavorable outcome included pupillary abnormality on admission and brain bulging during surgery. INTERPRETATION: Therapeutic effectiveness of hypothermia was thus limited in patients who presented with these grave symptoms.

Adolescent↗
PubMed2001

Expression and localization of MGP in rat tooth cementum.

Tooth cementum, a calcified hard tissue covering the root surfaces, is an important component connecting the teeth to the collagenous fibres of the periodontal ligament. Although the overall composition of cementum may closely resemble that of bone, each part has not been fully characterized. Here, the localization of the matrix gamma-carboxyglutamic acid (Gla) protein (MGP), one of the major Gla-containing proteins in the body, in cementum was investigated using immunohistochemistry and in situ hybridization. (1) Strong MGP antigenicity was observed in the acellular cementum, but was only moderate in the cellular cementum; (2) polygonal periodontal ligament cells facing the acellular cementum and the uncalcified cellular cementum expressed MGP mRNA, indicating that these cells produced MGP and deposited it on the cementum; (3) MGP accumulated at the junction between the uncalcified and calcified cellular cementum; and (4) the distribution pattern of MGP antigenicity resembled that of osteopontin. As one function of MGP could be as a negative regulator for mineral apposition, the expression of MGP in the cells adjacent to the cementum may be important to prevent hyperapposition of minerals.

Animals↗
PubMed2001

Dopamine and serotonin uptake inhibitors on the release of dopamine and serotonin in the nucleus accumbens of young and aged rats.

Nucleus accumbens (ACC) of young (4 months old) and aged (24 months old) Wistar rats were perfused with dopamine (DA) uptake blocker, cocaine, or the serotonin (5-HT) selective reuptake inhibitor, fluoxetine, through the microdialysis probe membrane, used to assess the dopamine transporter (DAT) or serotonin transporter (SERT) modulation. The basal extracellular DA release in the ACC was significantly lower in aged rats than young rats. Analysis of DA and 5-HT concentrations in the ACC with increased positive GFAP revealed that DA and DOPAC levels of aged rats were decreased to 55 and 60% of those in young rats, respectively. After co-perfusion with cocaine, both DA and 5-HT releases in the ACC were increased in the young and aged groups. However, the magnitude of the increased DA release was lower in aged rats than young rats. Co-perfusion with fluoxetine showed lower magnitude of the increased DA release in aged rats. It appears that the DAT and SERT system responds initially to ACC cell loss with age, and that especially ACC DAT in the aged rat is more degenerative compared with the young rats. These findings suggest that the serotonergic system with SERT in the remaining ACC neurons show an early adaptive response and resistance to the normal aging and maintain the multiple regulatory system in the ACC despite neural loss since the dopaminergic neurons in the aged animals are vulnerable to aging.

Aging↗
PubMed2001

Mapping and promoter sequencing of HNF-1beta gene in diabetes-prone and -resistant mice.

By using a novel single nucleotide polymorphism (SNP) in the coding sequence, the chromosomal location of Tcf2, encoding hepatic nuclear factor (HNF)-1beta, was determined in F2 intercrosses between Nagoya-Shibata-Yasuda (NSY) mice, an animal model of type 2 diabetes, and control C3H/He mice. The promoter region of Tcf2 gene was sequenced in NSY, non-obese diabetic (NOD) and control C3H/He mice. Tcf2 was mapped between genetic markers D11MIT320 and D11MIT195 with the following distances: D11MIT320-(7.3 cM)-Tcf2-(0.5 cM)-D11MIT195. A variant with insertion of C between -205 and -204 in the promoter region of Tcf2 was identified in NSY mice, but not NOD and C3H/He mice.

Animals↗
PubMed2001

A case of autoimmune hepatitis with a high titer of antimitochondrial antibody and normal gamma-globulinemia.

We report here a patient with chronic active hepatitis who had no markers for hepatitis viruses and no hyper-gamma-globulinemia, but had high titers of antimitochondrial antibody. Serum levels of alkaline phosphatase were normal, and antinuclear antibody, antismooth muscle antibody, and antiliver kidney microsome antibody tested negative. The titers of antimitochondrial antibody exceeded 1:640, and the positivity for anti-M2 was ascertained by using both ELISA and immunoblot with beef-heart mitochondria and a recombinant pyruvate dehydrogenase E2 subunit as antigens. This patient responded to ursodeoxycholic acid (UDCA) therapy in the beginning, but her hepatitis flared up during UDCA therapy. In contrast, she responded completely to corticosteroid therapy. The clinical course and histological findings of this patient strongly suggest that this patient has autoimmune hepatitis.

Aged↗
PubMed2001

Clarification of the active gelatinolytic sites in human ovarian neoplasms using in situ zymography.

Tissues from 26 human ovarian common epithelial tumors were examined to determine where and how gelatinolytic activity was present, in relation to tumor-stromal interaction and histologic types. For this purpose, we used in situ zymography, a newly developed technique using gelatin-coated film. Gelatinolytic activity was evident in ovarian carcinomas and in borderline tumors. Benign tumors had no or only weak activity. Four tissue localization patterns of gelatinolysis were identified: pattern A, tumor cytoplasm; pattern B, tumor-stromal junction; pattern C, stroma; and pattern D, cystic fluid. Mucinous cystadenocarcinomas showed A and/or D patterns. One mucinous and one serous adenocarcinoma and one mucinous borderline tumor had a B pattern. Most serous and all clear cell adenocarcinomas showed strong gelatinolysis of C pattern, especially in the desmoplastic stroma, an area where the tumor cells were dispersed. Immunohistochemically in 12 adenocarcinomas and 3 borderline tumors, the tumor cytoplasm was positive for matrix metalloproteinases (MMP-2) (5 cases), MMP-7 (9 cases), and MMP-9 (6 cases). Stromal components were positive for MMP-2 in 5 cases and for MMP-9 in 3 cases, but they were not positive for MMP-7. MMP antigens were mostly distributed in an almost identical pattern consistent with that seen with in situ zymography. In situ zymography clarified the cellular localization of active gelatinolysis in human ovarian neoplasms, a finding which supports the view that interaction between tumor and stroma is critical for tumor growth. This newly developed method contributes to a better understanding of biologic features of ovarian malignancies.

Adenoma↗
PubMed2001

Insulin secretion to glucose as well as nonglucose stimuli is impaired in spontaneously diabetic Nagoya-Shibata-Yasuda mice.

To clarify the mechanisms of impaired insulin secretion in Nagoya-Shibata-Yasuda (NSY) mice, an inbred strain of mice with spontaneous development of type 2 (non-insulin-dependent) diabetes mellitus, the insulin response to glucose (5.5 to 27.8 mmol/L) and nonglucose stimuli (glibenclamide, arginine, and BayK8644, a Ca-channel opener) was studied in vitro using isolated islets from male NSY and control C3H/He mice at 36 weeks of age by the batch incubation method. Insulin response to 5.5 mmol/L glucose was not significantly different between NSY and C3H/He mice, but insulin response to a high concentration of glucose (> or = 11.1 mmol/L) was significantly smaller in NSY mice than in control C3H/He mice. The dose-response curve of insulin secretion showed a markedly reduced maximum response, but almost normal glucose sensitivity in NSY islets. Insulin responses to glibenclamide (1 mmol/L), arginine (20 mmol/L), and BayK8644 (0.1 mmol/L) were also significantly smaller in NSY mice than in C3H/He mice. Insulin content of islets, in contrast, was significantly higher in NSY mice than in C3H/He mice. The impaired insulin response to glucose and nonglucose stimuli together with higher insulin content in islets in the NSY mouse suggest that a defect in voltage-dependent Ca(2+)-channel or thereafter in the cascade of insulin secretion may be responsible for impaired insulin secretion in NSY mice. NSY mice, therefore, could be a novel animal model of type 2 diabetes with a defect in insulin secretion at a different site from that in previously known animal models.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Assessment of coronary flow velocity reserve using fast velocity-encoded cine MRI for noninvasive detection of restenosis after coronary stent implantation.

PURPOSE: Serial change of the coronary flow velocity reserve was evaluated with fast velocity-encoded cine magnetic resonance imaging (MRI) for noninvasive detection of restenosis after coronary stent implantation. METHOD: In total, 60 MRI flow studies were performed in 10 patients with coronary artery disease who undersvent elective successful stent implantation to the lesion in the proximal left anterior descending artery. Flow velocities in the segment that was distal to the stent were measured before and after intravenous injection of dipyridamole. MRI measurements of coronary flow velocity reserve were repeated every 4 weeks for 6 months, and follow-up angiography was performed 6 months after the procedure. RESULTS: In patients without restenosis (n = 7, % diameter stenosis: 27.8%+/-7.1) at follow-up angiography, the coronary flow velocity reserve remained normal during the 6-month follow-up time. The flow velocity reserve was 2.31+/-0.30 at 1 month and 2.52+/-0.25 at 6 months after stent implantation (p = NS). In contrast, the coronary flow velocity reserve showed a significant decrease after 4 months in patients with restenosis (n = 3, % diameter stenosis: 66.3%+/-8.1) at follow-up angiography. The flow velocity reserve was 2.26+/-0.49 at 1 month and 1.52+/-0.09 at 6 months after stent implantation (p < 0.05). CONCLUSION: Fast velocity-encoded cine MRI is a technique that shows promise in providing non-invasive detection of restenosis of coronary stent implantation.

Adult↗
PubMed2001

Tracing axons in the peripheral nerve using lacZ gene recombinant adenovirus and its application to regeneration of the peripheral nerve.

The usefulness of recombinant adenovirus with LacZ to trace axons in the peripheral nervous system was investigated. Recombinant adenovirus with LacZ was applied to the cut end of the tibial nerve in rats. The LacZ gene product (B-galactosidase) filled axons of the tibial nerve, which permitted the continuous long-range tracing of axons. Further, the branching and the direction of the branches could also be examined. Labeled axons in the tibial nerves ran parallel to each other without branching and kept this relative position in the tibial and the sciatic nerve. When the virus was introduced to the regenerating nerve using a silicon tube, the regenerating fibers grew tortuously with short branches in the bulge at the proximal end of the silicon tube. The fibers grew straight in the tube and passed through the bulge at the distal end of the tube without branching. These observations indicate that the LacZ gene recombinant adenovirus is a useful tracer for the study of the peripheral nervous system and of the regeneration processes.

Adenoviridae↗
PubMed2001

Dissociation of Bax from a Bcl-2/Bax heterodimer triggered by phosphorylation of serine 70 of Bcl-2.

Serine 70 in the loop region of Bcl-2 is specifically phosphorylated by paclitaxel-treatment in tumor cells and BHK cells expressing Bcl-2. The phosphorylation of serine 70 of Bcl-2 (pS70-Bcl-2) peaks 24 to 48 h after paclitaxel treatment and accelerates apoptosis. Phosphorylation is effectively inhibited in the presence of actinomycin D or cycloheximide, which restore cell viability to the same level as control cells not expressing Bcl-2. These results indicate that paclitaxel-induced kinase(s) and/or its activator(s) are synthesized de novo and play an important role in paclitaxel-induced apoptosis by phosphorylating Bcl-2. In binding assays using the phosphorylation-specific antibody against pS70-Bcl-2, the induction of serine 70 phosphorylation 70 results in a loss of the binding ability of Bcl-2 to Bax, a pro-apoptotic partner, and induces subsequent cell death. When the pS70-Bcl-2 antibody was added to human breast cancer tissue, serine 70 phosphorylation was also detected, even prior to treatment with anticancer agents. Further study of breast cancers revealed 83% of tumors with high pS70-Bcl-2 expression responded to paclitaxel or docetaxel treatment, whereas 57% of those with low expression not respond. These findings suggest that pS70-Bcl-2 might be a predictive factor for prognosis and sensitivity to paclitaxel treatment for breast cancer.

Animals↗
PubMed2001

Isolation and characterization of oxygen-evolving thylakoid membranes and photosystem II particles from a glaucocystophyte, Cyanophora paradoxa.

Conditions for preparing oxygen-evolving thylakoid membranes and PSII complexes, and those for observing the PSII activity were investigated in a glaucocystophyte, Cyanophora paradoxa. The active thylakoid membranes were isolated either with a medium containing glycerol or with that containing high concentrations of sucrose, phosphate, and citrate. Active PSII particles were solubilized by octyl-beta-D-glucoside from thylakoid membranes and were separated by sucrose density gradient centrifugation. The thylakoid membranes and PSII particles showed an oxygen-evolving activity only in high-ionic-strength media. The extrinsic 33 kDa protein (PsbO) and the cytochrome c(550) (PsbV) were found to be present in the PSII particles as in cyanobacteria or red algae, but no 12 kDa protein (PsbU) was detected. The PsbO protein was classified as a land-plant type by its N-terminal amino acid sequence.

Absorptiometry, Photon↗
PubMed2001

Electroacupuncture stimulation suppresses the increase in alcohol-drinking behavior in restricted rats.

BACKGROUND: Although a number of studies on traditional eastern or Chinese medicine, such as acupuncture, moxibustion, and herbal drugs, have been reported, few reports describe electroacupuncture (EAC) effects on drug- and alcohol-seeking behaviors in animal models. The purpose of the present study was to investigate the effect of EAC on changes in alcohol-drinking behavior in rats challenged with restriction and immobilization stress. MATERIAL AND METHODS: Male Sprague Dawley rats (260-280 g) were tightly hung and immobilized in restriction models for 10 min. These immobilization stresses were performed twice a week for 1 week and for 3 consecutive weeks for the short- and long-restricted stress groups, respectively. EAC was applied for 10 min to the hindlimb point, Tsu-San-Li (ST 36), and the lumbar point, Shen-Shu (BL 23). These points are used to treat mental and psychosomatic disorders and are known clinically to produce a sedation effect. Time-access alcohol-drinking behavior was determined at 24 hr after the termination of EAC. Finally, brain dopamine (DA) levels were assayed in the two groups. A sham-control group underwent only restricted stress without EAC. RESULTS: Time-access alcohol-drinking behavior increased significantly in the long-restricted group compared with the short-restricted group and controls. EAC applied to the ST 36 (Tsu-San-Li) point suppressed the increased alcohol-drinking behavior in restricted rats. However, EAC applied to the Shen-Shu (BL 23) point was not effective, because alcohol-drinking behavior was significantly increased in long-restricted rats compared with short-restricted rats. Striatal DA levels of restricted rats with EAC stimulated at Tsu-San-Li were increased significantly compared with the rats with EAC applied to the Shen-Shu point. CONCLUSION: These findings suggest that EAC applied at ST 36 (Tsu-San-Li) was more effective for reducing the increased alcohol-drinking behavior in restricted rats, and they showed that a point specific in EAC procedure was associated with an increase of striatal DA levels. These findings provide new information for understanding alcohol-drinking behavior and for treating human alcoholics.

Alcohol Drinking↗
PubMed2001

Altered cytokine response in rat acute pancreatitis complicated with endotoxemia.

We demonstrated that the dynamic aspects of cytokine production in rat acute pancreatitis, which was induced by cerulein and aggravated by subsequent lipopolysaccharide (LPS) injection. A priming effect by induction of mild pancreatitis with cerulein enhanced the subsequent cytokine production by LPS injection. Alternatively, after induction of severe pancreatitis with cerulein and LPS, cytokine production was markedly suppressed for > or = 90 hours. Production of interleukin-2 (IL-2) by splenocytes decreased, and mortality rate after cecal ligation and puncture (CLP) increased significantly after induction of severe acute pancreatitis. These results suggest that the suppression of a cytokine response in severe acute pancreatitis may alter the defense system and, as a result, increase mortality after CLP.

Acute Disease↗