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H Shibata

Publications and source records attributed to H Shibata.

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

Seasonal distribution of enteropathogens detected from diarrheal stool and water samples collected in Kathmandu, Nepal.

A total of 334 diarrheal fecal samples (from 210 males and 124 females) collected in Kathmandu, Nepal, were studied for various kinds of enteropathogens. Overall, 33% (111/334) fecal samples were positive for one or more enteropathogens. There was no difference in detection rates between males and females. Enteropathogen detection rates in summer, winter, spring, and autumn were 61% (40/66), 52% (45/87), 31% (25/81), and 25% (25/100), respectively. Altogether eight species of bacteria, three genera of viruses, and five species of protozoan parasites were detected with considerable seasonal variations. Among the bacterial isolates, enteropathogenic Escherichia coli topped the list followed by Vibrio sp. Only one sample had Shigella (S. sonnei). Rotavirus type A was the most frequently detected among the enteric viruses, followed by human enterovirus and human adenovirus, respectively. Among the enteric protozoan parasites, Giardia intestinalis was the most frequently detected followed by Cryptosporidium parvum. Detection of bacterial and protozoan pathogens showed a slightly high tendency in the summer season compared with that in the other seasons (p>0.05), whereas the detection of viruses was significantly high in the winter season (p<0.05). Of the total 57 water samples, 43 (75%) showed one or more bacterial species out of which 51% (22/43) were E. coli. Among the E. coli isolates, 68% were EPEC. Enterohemorrhagic E. coli (O157) was not detected.

Adolescent↗
PubMed2000

Direct interaction of Rab4 with syntaxin 4.

In the present study, we examined the possible interaction between Rab4 and syntaxin 4, both having been implicated in insulin-induced GLUT4 translocation. Rab4 and syntaxin 4 were coimmunoprecipitated from the lysates of electrically permeabilized rat adipocytes. The interaction between the two proteins was reduced by insulin treatment and increased by the addition of guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). An in vitro binding assay revealed that the bacterially expressed Rab4 was bound to a glutathione S-transferase fusion protein containing the cytoplasmic domain of syntaxin 4 (GST-syntaxin 4-(1-273)) but not to syntaxin 1A or vesicle-associated membrane protein-2. The interaction between Rab4 and syntaxin 4 seemed to be regulated by the guanine nucleotide status of Rab4, because 1) GTPgammaS treatment of the cells significantly increased, but guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS) treatment decreased the amount of Rab4 pulled down with GST-syntaxin 4-(1-273) from the cell lysates; 2) GTPgammaS loading on Rab4 caused a marked increase in the affinity of Rab4 to syntaxin 4 whereas GDPbetaS loading had little effect; and 3) a GTPase-deficient mutant of Rab4 (Rab4(Q67L)), but not a GTP-binding-defective mutant (Rab4(S22N)), was bound to GST-syntaxin 4-(1-273). Although insulin stimulated [gamma-(32)P]GTP binding to Rab4 in a time-dependent fashion, its effect on the Rab4 interaction with syntaxin 4 was apparently biphasic; an initial increase in Rab4 associated with syntaxin 4 was followed by a gradual dissociation of the GTPase from syntaxin 4. Finally, the binding of Rab4(Q67L) to GST-syntaxin 4-(1-273) was inhibited by munc-18c in a dose-dependent manner, indicating that GTP-loaded Rab4 binds to syntaxin 4 in the open conformation. These results suggest that 1) Rab4 interacts with syntaxin 4 in a direct and specific manner, and 2) the interaction is regulated by the guanine nucleotide status of Rab4 as well as by the conformational status of syntaxin 4.

Adipocytes↗
PubMed2000

Functional evaluation of PTEN missense mutations using in vitro phosphoinositide phosphatase assay.

The tumor suppressor gene PTEN is frequently mutated in diverse human cancers and in autosomal dominant cancer predisposition disorders. Recent studies have shown that the lipid phosphatase activity of PTEN is critical for its tumor suppressor function and that PTEN negatively regulates the phosphatidylinositol 3'-kinase-protein kinase B pathway. Although more than half of PTEN mutations result in protein truncation, a significant fraction of PTEN mutations are missense mutations. To examine whether tumor-derived and germ-line-derived missense mutations inactivate PTEN lipid phosphatase function, we constructed 42 distinct types of PTEN missense mutations and expressed them in Escherichia coli. The purified (His)6-tagged PTEN proteins were tested for their ability to dephosphorylate inositol 1,3,4,5-tetrakisphosphate and phosphatidylinositol 3,4,5-triphosphate. In addition, we examined the effect of mutant PTENs on the ability of PTEN to bind to the phospholipid membrane. The results revealed that the majority of PTEN missense mutations [38 of 42 (90%)] eliminated or reduced phosphatase activity and that all of the mutations examined had no effect on the membrane binding activity of PTEN. Our study indicated that phosphoinositide phosphatase activity is important for the tumor suppressor function of PTEN and that there may be other mechanisms of PTEN inactivation that are not monitored by in vitro phosphatase assay and in vitro membrane binding assay.

Escherichia coli↗
PubMed2000

A novel protein with RNA-binding motifs interacts with ataxin-2.

Spinocerebellar ataxia type 2 (SCA2) is caused by expansion of a polyglutamine tract in ataxin-2, a protein of unknown function. Using the yeast two-hybrid system, we identified a novel protein, A2BP1 (ataxin-2 binding protein 1) which binds to the C-terminus of ataxin-2. Northern blot analysis showed that A2BP1 was predominantly expressed in muscle and brain. By immunocfluorescent staining, A2BP1 and ataxin-2 were both localized to the trans -Golgi network. Immunocytochemistry showed that A2BP1 was expressed in the cytoplasm of Purkinje cells and dentate neurons in a pattern similar to that seen for ataxin-2 labeling. Western blot analysis of subcellular fractions indicated enrichment of A2BP1 in the same fractions as ataxin-2. Sequence analysis of the A2BP1 cDNA revealed an RNP motif that is highly conserved among RNA-binding proteins. A2BP1 had striking homology with a human cDNA clone, P83A20, of unknown function and at least two copies of A2BP1 homologs are found in the Caenorhabditis elegans genome database. A2BP1 and related proteins appear to form a novel gene family sharing RNA-binding motifs.

Adult↗
PubMed2000

Actin filaments play a critical role in insulin-induced exocytotic recruitment but not in endocytosis of GLUT4 in isolated rat adipocytes.

Actin-based cytoskeletons have been implicated in insulin-stimulated glucose transport and translocation of the insulin-regulated glucose transporter, GLUT4, from the intracellular pool to the plasma membrane. However, most previous studies were done using adherent cell systems such as L6 myotubes and 3T3-L1 adipocytes, and very little information is available on the significance of the actin filaments to the insulin action in isolated adipocytes, a widely used experimental system. In the present study, we investigated the physiological role of actin filaments in the subcellular trafficking of GLUT4 in isolated rat adipocytes. We first compared the effects of two actin-disrupting reagents, latrunculin A and cytochalasin D, on the organization of the actin filaments as well as on the insulin action on glucose transport by laser confocal microscopy combined with biochemical analysis of the insulin action. Treatment of the cells with latrunculin A induced dose- and time-dependent disappearance of the filamentous actin, which correlated very well with inhibition of the insulin effect on glucose transport. Although cytochalasin D at 50 microM significantly inhibited insulin-stimulated glucose transport, it was not effective in disassembly of the actin filaments; rather, many intense punctate signals were observed in cytochalasin D-treated cells. In the actin-disrupted adipocytes treated with latrunculin A, insulin-induced GLUT4 translocation was inhibited completely. In addition, latrunculin A remarkably inhibited both insulin-induced glucose transport and GLUT4 translocation in the presense of D(k)-(62-85), a potent inhibitor of GLUT4 endocytosis, suggesting that intactness of the actin filaments was necessary for insulin-induced exocytosis of the GLUT4-containing vesicles. On the other hand, latrunculin A showed little inhibitory effect on either endocytosis of the trypsin-cleaved 35-kDa fragment of GLUT4 or decay of the glucose transport activity after addition of wortmannin in insulin-stimulated cells. The results of our experiment show clearly that, in rat adipocytes, (i) latrunculin A may be a more suitable tool than cytochalasin D for disruption of actin filaments, and (ii) actin filaments play a crucial role in exocytotic recruitment of GLUT4 to the plasma membrane from the intracellular pool, but not in its endocytosis.

Actins↗
PubMed2000

Properties of fucoidan from Cladosiphon okamuranus tokida in gastric mucosal protection.

To elucidate the anti-ulcer potential of Cladosiphon fucoidan, anti-peptic activity, bFGF stabilizing activity and inflammatory properties of this and related substances were investigated. Anti-peptic activity was observed with this and other sulfated polysaccharides such as dextran sulfate, carrageenan, and Fucus fucoidan. However, non-sulfated polysaccharides such as mannan and dextran did not exert the anti-peptic activity. The loss of bFGF bioactivity was prevented by all sulfated polysaccharides tested except chondroitin sulfate, at pH 7.4 and at pH 4.0. At pH 2.0, only heparin protected the bFGF activity. The generation of superoxide by macrophages and PMNs was stimulated by dextran sulfate, carrageenan, and Fucus fucoidan, whereas Cladosiphon fucoidan, heparin and chondroitin did not. Dextran sulfate, carrageenan, and Fucus fucoidan also stimulated the secretion of TNFalpha from macrophages, while Cladosiphon fucoidan did not. Thus, Cladosiphon fucoidan is a sulfated polysaccharide without inflammatory action. These results suggest that Cladosiphon fucoidan is a safe substance with potential for gastric protection.

Animals↗
PubMed2000

Factors relating to place of death of Japanese people from a small town in a rural area.

The objective of our retrospective study was to clarify factors relating to place of death of Japanese people from a small town in a rural area who had been bedridden for at least one week before dying. The caregivers of subjects aged 40 and above who died during a three-year period were surveyed by trained interviewers. Of 352 subjects who died, 312 caregivers responded and agreed to a face-to-face interview. A total of 213 subjects were considered as an eligible sample. The main outcome measures were odds ratios for death at home in relation to age, pain, cause of death, and home visit service. One hundred and two people died at home, while 112 people died in a hospital. Multivariate logistic regression analysis showed that the probability of home death increased with age of the bedridden, lack of pain during the bedridden period, not having cancer as a cause of death, having senility as a cause of death, and receiving regular home visits by a Public Health Nurse. In conclusion, expansion of the home visit programs by Public Health Nurses may enable people to die at home as they so desire. Further prospective research is needed to explore the association between the attitude toward terminal care and the place of death.

Adult↗
PubMed2000

l-Ephedrine is a major constituent of Mao-Bushi-Saishin-To, one of the formulas of Chinese medicine, which shows immediate inhibition after oral administration of passive cutaneous anaphylaxis in rats.

OBJECTIVE AND DESIGN: Whether Mao-Bushi-Saishin-To (MBST), one of the formulas of classical Chinese medicine, is effective on 48-h passive cutaneous anaphylaxis (PCA) in rats and which substance in the formula is responsible for its inhibitory action were examined. TREATMENT: In the studies on PCA, MBST (hot water extract of the whole herbal formula), extracts of Ephedra herb (Mao), l-ephedrine and other reference drugs were orally administered immediately or at various times before or 5 min after the antigen challenge. In the experiments on anaphylactic histamine release from rat peritoneal mast cells, l-ephedrine and d-pseudoephedrine were added at 10(-4)-10(-7) g/ml at 30, 10, 3 or 0 min before antigen provocation. RESULTS: The time course study indicated that MBST produced a prompt and long lasting inhibition of PCA. Among the constituents of Mao, l-ephedrine exerted this prompt inhibitory activity, but d-pseudoephedrine did not. Neither pseudoephedrine nor l-ephedrine prevented the anaphylactic histamine release from isolated peritoneal mast cells. CONCLUSIONS: It is strongly emphasised that the rapid suppression of PCA by orally administered l-ephedrine must be exerted by a mechanism distinct from that of suppression produced following gastrointestinal absorption of the drug, because the time required for the inhibition was extraordinarily short. However, direct inhibition of anaphylactic histamine release from isolated mast cells was excluded in this inhibition of PCA.

Animals↗
PubMed2000

Immediate inhibition by oral l-ephedrine of passive cutaneous anaphylaxis of rats: indirect inhibition of anaphylactic chemical mediator release from the mast cell.

OBJECTIVE AND DESIGN: We previously reported that oral l-ephedrine showed extraordinarily rapid inhibition of 48-h passive cutaneous anaphylaxis (PCA) in rats. In the present study, in vivo and in vitro experiments were performed to elucidate a possible mechanism for the inhibition. MATERIALS: Rat antiserum was prepared with dinitrophenylated Ascaris suum extract + Bordetella pertussis. TREATMENT: Wistar rats were passively skin-sensitised, actively sensitised or non-sensitised. l-Ephedrine immediately before provocations was orally or intravenously administered in in vivo experiments. In in vitro experiments, the drug was added at various time and concentrations before the challenge. METHODS: The intensity of PCA was assessed by dye leakage method. Histamine and serotonin released in vitro or retained in the skin in vivo by anaphylaxis were assayed fluorometrically. RESULTS: Oral l-ephedrine rapidly inhibited the PCA by inhibiting the release of histamine and serotonin from the reaction site, whereas anaphylactic histamine and serotonin releases from skin fragments were not affected by the drug. Furthermore, the orally administered drug influenced neither the histamine- nor serotonin-induced cutaneous vascular permeability. CONCLUSIONS: These results were strongly indicative that the prompt suppression of the PCA by oral l-ephedrine was not exerted following the drug was absorbed from the gastrointestinal tract. Thus, the result may be from an indirect inhibition of chemical mediator release, possibly through an unidentified stimulation of the nervous system, but not from the inhibition of chemical mediator release by the direct interaction of drug to mast cells and not from the decreased vascular permeability.

Administration, Oral↗
PubMed2000

Oral beta-stimulants can inhibit passive cutaneous anaphylaxis in rats through an indirect inhibitory mechanism: possible involvement of afferent and efferent nervous system via gastric beta2-adrenoceptor stimulation.

OBJECTIVE AND DESIGN: We previously demonstrated that oral l-ephedrine exerts an extremely rapid (within 20 s) inhibition of 48-h passive cutaneous anaphylaxis reaction (PCA) in rats by a possibly unidentified mode of action. In the present experiments, we elucidated the mechanism of the PCA inhibition by l-ephedrine using adrenoceptor agonists and antagonists. MATERIALS: Rat antiserum was prepared with dinitrophenylated Ascaris suum extract + Bordetella pertussis. TREATMENT: Passively skin-sensitised Wistar rats were mainly used. l-Ephedrine, and adrenoceptor agonists and antagonists were orally administered immediately before PCA provocation. Catecholamine depleting (6-hydroxydopamine, 6-OHDA), amine depleting (reserpine) or ganglion blocking (hexamethonium) agent was intraperitoneally or intravenously administered before the provocation. METHODS: The effects of the drugs on PCA were assessed by inhibition of the dye leakage. RESULTS: beta-(propranolol) and beta2-(butoxamine) blocking agents reduced the inhibition of PCA by l-ephedrine, while the inhibition was not altered by either an a-blocking agent (phentolamine) or a beta1-(atenolol) selective antagonist. On the other hand, beta-(isoproterenol) and beta2-selective (salbutamol) agonists showed extremely rapid inhibition of PCA. However, the beta-selective agonist (dobutamine) had no effect on the reaction. The pretreatment with hexamethonium, reserpine or 6-OH-DA substantially attenuated the inhibitory effect of l-ephedrine on PCA. CONCLUSIONS: The results strongly suggest that beta2-adrenoceptors locate in the stomach and that their receptor excitement finally may lead to the inhibition of PCA via the stimulation of the central and peripheral nervous systems.

Adrenergic beta-2 Receptor Agonists↗
PubMed2000

Molecular analysis of alpha-thalassemia in Nepal: correlation with malaria endemicity.

Thalassemia is a prevalent hereditary disorder characterized by impaired synthesis of globin chains. It has been suggested that the high frequency of thalassemia might reflect heterozygote advantage due to reduced susceptibility to malaria. In Nepal, malaria has often occurred in places below the altitude of 1,200m. We carried out a microepidemiological study on thalassemia in two neighboring populations in Nepal, the Danuwar and the Tamang. Settlements of the Danuwar are located below the limit of the malarial zone (1,200m in altitude), whereas those of the Tamang are found in malaria-free uplands. Three heterozygotes for hemoglobin E (HbE) were observed in the Danuwars. We detected one type (-alpha3.71) of alpha+-thalassemia that involves a deletion of 3.7kb, leading to a loss of one of two alpha-globin genes, in the Danuwars, at a high gene frequency of 63%, while the gene frequency in the Tamangs was only 5%. Analysis of the alpha-globin gene cluster revealed that four different haplotypes were associated with the type of alpha+-thalassemia in the Danuwars. Nucleotide sequences of the D-loop region in the mitochondrial DNA of the two populations indicated a similar nucleotide diversity in each population. The fixation index, FST, representing the degree of genetic differentiation estimated from mitochondrial DNA diversities (FST, 0.05), was smaller than that obtained from the gene frequencies of alpha-thalassemia (FST, 0.55). If we assume neutral molecular evolution in the D-loop region of mitochondrial DNA, these results suggest that the high frequency of alpha+-thalassemia may be due to biological adaptation to the malarial environment rather than to events such as a bottleneck.

DNA, Mitochondrial↗
PubMed2000

Organization of retrosplenial cortical projections to the laterodorsal thalamic nucleus in the rat.

The organization of the projections from the retrosplenial cortex (areas 29a--d) to the laterodorsal thalamic nucleus (LD) was examined in the rat with axonal transport of the cholera toxin B subunit and biotinylated dextran amine. The results showed that an area of the retrosplenial cortex provides ipsilateral projections to a distinct part of the LD at the level of its rostral two-thirds. The projections originate from layer VI and, to a lesser extent, layer V cells of the retrosplenial cortex. Area 29a and area 29b project, respectively, to the dorsolateral and the dorsomedial part of the LD. Area 29c projects to the ventromedial two-thirds of the LD, in a topographic pattern such that the rostral part of area 29c projects more ventromedially within the projection field than the caudal part of area 29c. Area 29d projects to the ventrolateral two-thirds of the LD in a topographic pattern similar to area 29c; the rostral part of area 29d projects more ventromedially within the projection field than the caudal part. These precise topographic projections from the retrosplenial cortex to the LD may constitute part of the circuitry underlying spatial navigation and various memory and emotional functions.

Animals↗
PubMed2000

Phytochemical flavones isolated from Scutellaria barbata and antibacterial activity against methicillin-resistant Staphylococcus aureus.

A crude extract prepared from Scutellaria barbata D. Don (Lamiaceae) was analyzed in the effort to discover antibacterial compounds against high-level strains of methicillin-resistant Staphylococcus aureus (MRSA). Apigenin and luteolin were isolated from the plant as active constituents against the bacteria. These flavonoid congeners were selectively toxic to S. aureus, including the MRSA and methicillin-sensitive S. aureus strains.

Anti-Bacterial Agents↗
PubMed2000

Urinary steroid profile in adrenocortical tumors.

Determination of the urinary steroid profile has been proposed as a sensitive tool for diagnosing adrenocortical tumors. The urinary steroid profiles were determined for patients with adrenocortical tumors. Urinary steroids were extracted, derivatized to form methyloxime-trimethylsilyl ether and analyzed by gas chromatography/mass spectrometry. Patients with adrenal adenomas from primary hyperaldosteronism had increased metabolites of 18-hydroxycorticosterone and aldosterone, and those with Cushing's syndrome had elevated excretion of 11 -deoxycortisol, cortisol, 18-hydroxycortisol, and cortisone metabolites. In patients with adrenocortical carcinomas, increased levels of metabolites of 11-deoxycortisol or 33-hydroxy-5-ene steroids were observed. The urinary steroid profiles of adrenal adenomas and adrenocortical carcinomas were quite different, suggesting the diagnostic validity for discriminating malignant from benign diseases.

Adenoma↗
PubMed2000

Effect of shitei-to, a traditional Chinese medicine formulation, on pentylenetetrazol-induced kindling in mice.

This study measured the effects of Shitei-To (STT), a traditional Chinese Medicine, which is a mixture of extracts from three medicinal herbs, Shitei (SI, Kaki Calyx; calyx of Diospyros kaki L. f.), Shokyo (SK, Zingiberis Rhizoma; rhizome of Zingiber officinale Roscoe) and Choji (CJ, Caryophylli flos; flowerbud of Syzygium aromaticum [L.] Merrill et. Perry), has long been used for the treatment of hiccups in Japan and China, against fully pentylenetetrazol-kindled seizures and on the development of pentylenetetrazol kindling in mice. Repeated administration of STT (3.0 g/kg p.o.) mildly retards the development of pentylenetetrazol-induced kindling in mice. STT also decreased the number of tonic-clonic convulsions resulting from progression kindling. On the other hand, STT had no effect on convulsions in fully pentylenetetrazol-kindled mice. These findings suggest that STT protects against the development of convulsions, and that STT may have therapeutic effects in the prevention of secondarily generalized seizures.

Animals↗
PubMed2000

Is autonomic dysfunction a necessary condition for chronic peptic ulcer formation?

BACKGROUND: The relationship between 1/f fluctuation of the heart rate variability and Helicobacter pylori infection was evaluated, in order to clarify whether autonomic nervous dysfunction is a necessary condition for chronic peptic ulcer formation. METHODS: The subjects were 11 patients with recurrent chronic peptic ulcer and 20 age-matched normal subjects. Holter ECGs were recorded over 24 h, and the 1/f(-x) fluctuation of the heart rate was computed. The 1/f(-x) fluctuation of the heart rate is a novel index of autonomic function that has been shown to reflect a patient's pleasant mood. For 1/f(-x) fluctuation, the slope of the regression line (-x) was determined and cosine fitting of the absolute slope of the regression line over a 24-h period was performed. RESULTS: For the normal group, the absolute slope of the regression line during daytime and night-time were 0.53 +/- 0.16 and 1.05 +/- 0.18, respectively. For the peptic ulcer group, the corresponding values during daytime and night-time were 0.94 +/- 0.15 and 1.84 +/- 0.18, respectively. The mean value of the cosine curve was 0.76 +/- 0.23 in the normal group and 1.12 +/- 0.25 in the peptic ulcer group. Thus, these values were significantly higher for the latter group than for the former group (P<0.05). No statistically significant difference in H. pylori infection between the two groups was observed. CONCLUSIONS: Autonomic nervous dysfunction as well as H. pylori infection appears to be a necessary condition for chronic peptic ulcer formation.

Aged↗
PubMed2000

The paternal methylation imprint of the mouse H19 locus is acquired in the gonocyte stage during foetal testis development.

BACKGROUND: Germline-specific differential DNA methylation that persists through fertilization and embryonic development is thought to be the 'imprint' distinguishing the parental alleles of imprinted genes. If such methylation is to work as the imprinting mechanism, however, it has to be reprogrammed following each passage through the germline. Previous studies on maternally methylated genes have shown that their methylation imprints are first erased in primordial germ cells (PGCs) and then re-established during oocyte growth. RESULTS: We have examined the timing of the reprogramming of the paternal methylation imprint of the mouse H19 gene during germ cell development. In both male and female PGCs, the paternal allele is partially methylated whereas the maternal allele is unmethylated. This partial methylation is completely erased in the female germline by entry into meiosis, establishing the oocyte methylation pattern. In the male germline, both alleles become methylated, mainly during the gonocyte stage, establishing the sperm methylation pattern. CONCLUSION: The paternal methylation imprint of H19 is established in the male germline and erased in the female germline at specific developmental stages. The identification of the timings of the methylation and demethylation should help to identify and characterize the biochemical basis of the reprogramming of imprinting.

Animals↗