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Biomedical subjects

H Shibata

Publications and source records attributed to H Shibata.

At least 37 records · Page 2Linked to original sources

Effects of surface soil removal on dynamics of dissolved inorganic nitrogen in a snow-dominated forest.

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3-) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3- from soil at the treated site and control sites were 257 and -12 mmol m(-2) year(-1), and about 57% of the net output at the treated site occurred during the snowmelt period. NO3- was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3- concentration of soil solution, and snowmelt strongly affected the NO3- leaching from treated soil and the NO3- restoration process in a snow-dominated region.

Ammonia↗

Regional comparison of nitrogen export to Japanese forest streams.

Nitrogen (N) emissions in Asian countries are predicted to increase over the next several decades. An understanding of the mechanisms that control temporal and spatial fluctuation of N export to forest streams is important not only to quantify critical loads of N, N saturation status, and soil acidification N dynamics and budgets in Japanese forested watersheds is not clear due to the lack of regional comparative studies on stream N chemistry. To address the lack of comparative studies, we measured inorganic N (nitrate and ammonium) concentrations from June 2000 to May 2001 in streams in 18 experimental forests located throughout the Japanese archipelago and belonging to the Japanese Union of University Forests. N concentrations in stream water during base flow and high flow periods were monitored, and N mineralization potential in soil was measured using batch incubation experiments. Higher nitrate concentrations in stream water were present in central Japan, an area that receives high rates of atmospheric N deposition. In northern Japan, snowmelt resulted in increased nitrate concentrations in stream water. The potential net N mineralization rate was higher in surface soil than in subsurface soil, and the high potential for N mineralization in the surface soil partly contributed to the increase in nitrate concentration in stream water during a storm event. Regional differences in the atmospheric N deposition and seasonality of precipitation and high discharge are principal controls on the concentrations and variations of nitrates in stream water in forested watersheds of Japan.

Ammonia↗

Marked reduction of Helicobacter pylori-induced gastritis by urease inhibitors, acetohydroxamic acid and flurofamide, in Mongolian gerbils.

Urease has been suggested to be essential for colonization and pathogenesis of Helicobacter pylori infection. In the present study, we evaluated the effects of urease inhibitors [acetohydroxamic acid (AHA) and flurofamide (FFA)] on H. pylori-induced gastritis in Mongolian gerbils. Animals were orally inoculated with H. pylori, and given urease inhibitors in their diet throughout the experimental period of six weeks or four weeks, starting from two weeks after H. pylori inoculation. With the administration of AHA at doses of 100, 500, and 2500 ppm throughout the experimental period, H. pylori-induced gastritis in animals was decreased in a dose-dependent manner, significantly so at 2500 ppm. Suppression of gastric lesions was also evident in animals administered 2500 ppm AHA after the H. pylori infection. Bacterial infection rates were reduced to 40-50% of the control value of 100%, by the highest dose of AHA. The potent urease inhibitor, FFA, also caused marked amelioration of H. pylori-associated gastritis on administration at 100 ppm throughout the six-week experimental period or for four weeks after H. pylori infection. Animals treated with FFA had few visible gastric lesions, and the proportion infected with H. pylori was reduced to less than 10%. Since antibiotic-resistant strains of H. pylori have become a serious problem, nonantibiotic urease inhibitors may be very useful to control H. pylori-associated gastroduodenal disease.

Administration, Oral↗

Stoichiometry of subunit e in rat liver mitochondrial H(+)-ATP synthase and membrane topology of its putative Ca(2+)-dependent regulatory region.

Previous studies have revealed that residues 34-65 of subunit e of mitochondrial H(+)-ATP synthase are homologous with the Ca(2+)-dependent tropomysin-binding region for troponin T and have suggested that subunit e could be involved in the Ca(2+)-dependent regulation of H(+)-ATP synthase activity. In this study, we determined the content of subunit e in H(+)-ATP synthase purified from rat liver mitochondria, and we also investigated the membrane topology of a putative Ca(2+)-dependent regulatory region of subunit e using an antibody against peptide corresponding to residues 34-65 of subunit e. Quantitative immunoblot analysis of subunit e in the purified H(+)-ATP synthase revealed that 1 mol of H(+)-ATP synthase contained 2 mol of subunit e. The ATPase activity of mitoplasts, in which the C-side of F(0) is present on the outer surface of the inner membrane, was significantly stimulated by the addition of the antibody, while the ATPase activity of submitochondrial particles and purified H(+)-ATP synthase was not stimulated. The antibody bound to mitoplasts but not to submitochondrial particles. These results suggest that the putative Ca(2+)-dependent regulatory region of subunit e is exposed on the surface of the C-side of F(0) and that subunit e is involved in the regulation of mitochondrial H(+)-ATP synthase activity probably via its putative Ca(2+)-dependent regulatory region.

Animals↗

Transverse Josephson plasma mode in T* phase SmLa(1-x)Sr(x)CuO(4-delta) single crystals.

Far-infrared reflectivity along the c axis in T* phase SmLa(1-x)Sr(x)CuO(4-delta) single crystals is measured down to 8 cm(-1). Below T(c), the conductivity peak is observed at 25 cm(-1) for x = 0.15 ( T(c) = 30 K) along with two reflectivity edges at 13 and 27 cm(-1). The conductivity peak is attributed to the transverse Josephson plasma mode between two longitudinal Josephson plasma modes, while the oscillator strength of the peak is found to be smaller than that calculated using the Josephson-coupled multilayer model. The difference is explained by assuming that only a few junctions at the disordered (La,Sr)(2)O(2-delta) block layer take part in the plasma oscillation with omega(pI(')) = 27 cm(-1).

Journal Article↗

Differential inhibitory mechanism of Fe2+ and Fe3+ on contraction of ileal longitudinal smooth muscle.

The mechanism of the inhibition of K(+)-induced contraction caused by ferrous (Fe(2+)) and ferric (Fe(3+)) ions were analysed in guinea-pig ileal longitudinal muscle and taenia coli. Fe(2+)increased the threshold for Ca(2+)-induced contraction in Ca(2+)-free, K(+)-depolarized taenia coli. However, Fe(3+)reduced the size of the maximal response to Ca(2+)without shifting the dose-response curves in taenia coli. Both 10 mM Fe(2+)and 2 mM Fe(3+)caused significant decreases in Ca uptake, as determined by the La method, during K(+)-induced ileal contraction. After treatment with 10 mM Fe(2+)in a state of cell membrane depolarization with K(+)for 30 min, the ileal K(+)-induced tonic contraction was completely restored by washing with medium containing EDTA, a chelator of divalent cations, and Fe(2+)remaining in muscle was almost eliminated by washing. In contrast, after treatment with 2 mM Fe(3+)in K(+)medium, K(+)-induced contraction was reversed only to a slight degree by washing with medium containing deferoxamine, a chelator of trivalent cations, and Fe(3+)in muscle largely remained despite the washing. These results suggest that Fe(2+)binds to the ileal surface membrane and reduces the contraction in response to K(+)mainly by inhibiting Ca(2+)influx. Fe(3+)may exert an inhibitory action on intracellular sites, in addition to the interference of Ca(2+)influx at the cell membrane.

Animals↗

Identification and expression of a mouse ortholog of A2BP1.

Human ataxin-2 contains a polyglutamine repeat that is expanded in patients with spinocerebellar ataxia type 2 (SCA2). Ataxin-2 is highly conserved in evolution with orthologs in mouse, Caenorhabditis elegans, and Drosophila melanogaster. It interacts at its C-terminus with ataxin-2 binding protein 1, A2BP1. This study presents a highly conserved mouse ortholog of A2BP1, designated A2bp1. The amino acid sequence of the human and mouse protein is 97.6% identical. This remarkable degree of conservation supports the fact that these proteins have an important basic function in development and differentiation. Sequence analysis reveals the existence of RNA binding motifs. The A2bp1 transcript was found in various regions of the CNS including cerebellum, cerebral cortex, brain stem, and thalamus/hypothalamus. The A2bp1 protein was detected by immunocytochemistry in the CNS and connective tissue of the mouse embryo starting at stage E11, as well as in the heart at all stages. Mouse embryos showed varying expression of A2bp1 at all stages. Previous studies in other model systems had implicated the orthologs of ataxin-2 and A2BP1 in development. This study suggests a role for A2bp1 in embryogenesis as well as in the adult nervous system, possibly mediated by a function in RNA distribution or processing.

Animals↗

Association analysis of polymorphisms in the upstream region of the human dopamine D4 receptor gene (DRD4) with schizophrenia and personality traits.

The human dopamine D4 receptor (DRD4) is of major interest in molccular studies of schizophrenia and personality traits. We examined the association of schizophrenia and polymorphisms in the upstream region of the DRD4 gene (-768G>A in the negative modulator region; -521C>T, -376C >T, and -291C>T in the cell type-specific promoter region; and -616C>G between the two regions) in 208 schizophrenic patients and 210 normal controls. No significant difference in genotype and allele frequencies was observed between the two groups, indicating that these polymorphisms do not make a major contribution to the pathogenesis of schizophrenia. We also studied the association of polymorphisms in the upstream region and a 48-bp repeat polymorphism in exon III of the DRD4 gene with personality traits in 173 Japanese individuals who completed the temperament and character inventory (TCI). The -768G>A polymorphism was significantly associated with reward dependence (P= 0.044), while no significant association was observed between novelty seeking and polymorphisms in the upstream region or the exon III repeat polymorphism of the DRD4 gene.

Base Sequence↗

Sesquiterpenoids from the fruits of Ferula kuhistanica and antibacterial activity of the constituents of F. kuhistanica.

Ethyl acetate extracts of the air-dried fruits of Ferula kuhistanica afforded three daucane esters: kuhistanicaol H, I and J, together with nine other known compounds. Their structures were established on the basis of spectroscopic evidence. Isolated compounds in this paper and previously reported compounds from the roots and stems of F. kuhistanica were tested for antibacterial activity. Some of them were selectively toxic against Gram-positive bacteria, including methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA).

Anti-Bacterial Agents↗

Phenylnaphthalene compounds from the subterranean part of Vitex rotundifolia and their antibacterial activity against methicillin-resistant Staphylococcus aureus.

A careful investigation of the subterranean part of Vitex rotundifolia has shown that this plant contains five novel lignans having a 1-phenylnaphthalene-type skeleton together with four known lignans. These structures were elucidated on the basis of spectroscopic data. Furthermore, some of the isolated compounds showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

Anti-Bacterial Agents↗

Estrogen receptor levels and lipid peroxidation in hepatocellular carcinoma with hepatitis C virus infection.

AIMS/BACKGROUND: Our preliminary studies showed that estradiol suppresses hepatic carcinogenesis and fibrogenesis in animal models. Hepatic estrogen receptors (ERs) medicate estradiol action in the liver. This study was performed to assess possible implications of menopause and hepatic ER levels for the development of cirrhosis with hepatocellular carcinoma (HCC). METHODS: One thousand, one hundred and ninety-nine consecutive HCC patients with hepatitis C virus (HCV)-related cirrhosis were divided into two groups, based on a menopausal age of 49 years. Liver tissues were obtained during surgical resection of HCC and metastatic liver tumor. RESULTS: The proportion of females among the HCC subjects < or =49 years of age was significantly lower (15.0%) than was the proportion of females among subjects >49 years of age (29.8%). Univariate analysis showed that HCV-related cirrhotic patients who developed HCC were more likely to have low hepatic levels of ER and copper-zinc superoxide dismutase (CuZn-SOD) protein and a high hepatic level of a lipid peroxidation product, malondialdehyde (MDA). Logistic regression identified age greater than 49 years (odds ratio [OR]: 7.9, 95% confidence interval [CI]: 2.8-21.3), male sex (OR: 3.5, 95% CI: 1.3-10.2), a decreased ER level (OR: 16.8, 95% CI: 7.3-34.6), and an increased MDA (OR: 8.3, 95% CI: 2.8-24.0) as the variables independently associated with the development of HCC in HCV-infected patients with cirrhosis. ER level was significantly correlated with CuZn-SOD level (r=0.583) and was inversely proportional to MDA level (r=-0.553). The study also showed that ER levels in the cirrhotic livers from premenopausal females were significantly higher than in male cirrhotic livers. CONCLUSIONS: These findings suggest that increased lipid peroxidation and impaired SOD function in the liver may be associated with decreased hepatic ER levels in HCV-infected patients with cirrhosis and HCC, and that HCV-related cirrhotic women before menopause might have the ability to protect against developing HCC via hepatic ER.

Age Factors↗

Structure and polymorphisms of the human metabotropic glutamate receptor type 2 gene (GRM2): analysis of association with schizophrenia.

Metabotropic glutamate receptors (mGluRs) belong to the class of GTP-binding protein coupled receptors and consist of eight different subtypes. The subtype 2 metabotropic glutamate receptor (mGluR2) gene (GRM2) is one of the possible candidate genes for schizophrenia. Phencyclidine (PCP)-induced increase in glutamate efflux and schizophrenia-like behavioral abnormalities were reduced by pretreatment of the mGluRII agonist LY354740 in rats and its effects are mediated via mGluR2. To evaluate involvement of the mGluR2 gene in the pathogenesis of schizophrenia, we isolated the human mGluR2 gene and determined the transcription initiation site, the entire nucleotide sequence and the chromosomal localization. The hmGluR2 gene spans 13 kb with six exons, including one non-coding exon. The gene was mapped to chromosome 3 p12-p11 by Radiation Hybrid Panel analysis. We screened polymorphisms in the coding exons of the mGluR2 gene, using the SSCP procedure. The thirteen polymorphisms identified included ten missense, one silent mutation and two one-base substitutions in the 5'-untranslated region. We genotyped 213 Japanese schizophrenics and 220 controls to study the association of polymorphisms in the mGluR2 gene with schizophrenia. As we found no statistically significant differences in allele frequencies of each polymorphism, these polymorphisms apparently do not play a major role in schizophrenia.

Brain Chemistry↗

Relationship among gastric motility, autonomic activity, and portal hemodynamics in patients with liver cirrhosis.

BACKGROUND AND AIMS: We examined the effects of the autonomic nervous function and the volume of portal blood flow to clarify the mechanism of the abnormal gastric motility in patients with liver cirrhosis. METHODS: Heart rate variability, electrogastrogram (EGG), and volume of portal blood flow were measured before and after a meal in 27 patients with liver cirrhosis (LC group) and in 20 normal subjects (N group). Autonomic nervous function was evaluated by using spectral analysis of heart rate variability. We used the cine phase-contrast (PC) method, using magnetic resonance imaging (MRI) to measure the portal flow, while the peak frequency and spectral power of the EGG were measured at pre- and postprandial change. RESULTS: The ratio of low frequency power to high frequency power (LF/HF) was significantly higher, and the HF power was significantly lower in the LC group than in the N group both before and after a meal. In both groups, the electrogastrographic peak power ratio before and after a meal showed a positive correlation with the HF ratio, and an inverse correlation with the LF/HF ratio. In addition, portal blood flow volume was significantly decreased in the LC group than in the N group. However, the increased rate of portal blood flow after a meal correlated positively with the increased rate of electrogastrographic peak power. Moreover, gastric motility was positively correlated with esophageal varices and coma scale with the use of multivariate analysis. CONCLUSIONS: Parasympathetic hypofunction, sympathetic hyperfunction and portal hemodynamics were closely related with gastric motility in cirrhotic patients. In addition, gastric motility was decreased, at least in part, by the ingestion of food in cirrhotic patients because of abnormalities in autonomic functions and portal blood flow following a meal.

Aged↗

Apoptosis as an independent prognostic indicator in squamous cell carcinoma of the esophagus.

Apoptosis plays a crucial role in determining net cell proliferation and cell turnover in various tumors. The rate of apoptosis in tumor cells has been reported to be a useful prognostic indicator in colorectal carcinoma. We examined apoptosis in 72 specimens of esophageal squamous cell carcinoma, by the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) digoxigenin-nick end labeling (TUNEL) method. We examined correlation of apoptosis with outcome, clinicopathological features, and expression of the apoptosis-related proteins p53 and Bcl-2. The percentage of apoptotic cells, or apoptotic index (AI), ranged from 0.8 to 9.4 (mean: 3.47; SD: 2.02). Overall, 5-year survival of patients with high AI (AI > or = 5.0; n = 18) tumors was significantly higher than that of patients with low AI tumors (AI < 5.0; n = 58; 76.9% versus 44.9%; P = 0.042). AI did not correlate significantly with the clinicopathological features of patient age and sex, depth of tumor and histological differentiation, lymph node metastasis, lymphatic invasion, or venous invasion. In p53-negative tumors, the AI was significantly higher than in p53-positive tumors. We concluded that AI may be a useful prognostic indicator in esophageal squamous cell carcinoma following curative surgery, and that apoptosis in this tumor is related to relative underexpression of p53 protein.

Adult↗

Quantitative analysis of red color sign in the endoscopic evaluation of esophageal varices.

BACKGROUND AND STUDY AIMS: Bleeding due to esophageal variceal rupture is associated with an extremely high mortality rate. Variceal bleeding is frequent in patients who have a red color sign on endoscopy. However, the red color sign is subjectively evaluated on the basis of color tone and the shape of the varices. To allow standardization and facilitate consensus, an objective method of assessing the red color sign is needed. In this study, a system was established for quantifying the red color sign during endoscopic evaluation. PATIENTS AND METHODS: Between July 1995 and February 1997, 55 untreated patients with portal hypertension and esophageal varices identified on upper gastrointestinal endoscopy were enrolled in the study. Images obtained about 5 cm oral to the esophagogastric junction during endoscopy were stored on magnetic optical disks using an endoscopic image processor. The still images were transmitted to a computer and analyzed using computer software. The RGB components (R, red; G, green; B, blue) were measured at points showing flare consistent with the red color sign. The endoscopic assessment was based on the Japanese Research Society for Portal Hypertension's general rules for recording endoscopic findings in esophagogastric varices. RESULTS: The ratio of the red color area to the variceal area increased with increasing red color grade. There were significant positive correlations between the R and G, and G and B components. This suggests that comparing the R components alone would allow assessment of the color differences in the red color area and in the varices. The R value was significantly higher in the red color area (115 +/- 20) than in the varices (57 +/- 19). An R value of 90 was found at the boundary between the two parts (P < 0.001). CONCLUSIONS: The red color area can be automatically calculated and quantified using the analysis program. Improvements in data storage methods may allow real-time evaluation during endoscopy in the future.

Aged↗

The role of cyclin-dependent kinase inhibitor p27 in squamous cell carcinoma of the esophagus.

The level of p27 expression decreases during tumor development and progression. Loss of p27 protein provides independent prognostic information in breast, prostate, colon, stomach and lung carcinomas. We generated a new polyclonal antibody against p27 and carried out immunohistochemical analysis of p27 expression in 61 specimens of esophageal squamous cell carcinoma, 10 carcinoma in situ specimens, and 5 squamous epithelial dysplasia specimens of the esophagus. We examined the correlation of p27 expression with various clinicopathologic features and prognosis. In squamous epithelial dysplasia, the p27-positive cells were located in the superficial normal-appearing cells, not in the atypical cells. In carcinoma in situ, the expression of p27 was markedly lower than in normal esophageal epithelium. In advanced squamous cell carcinomas, high p27 correlated significantly with the degree of differentiation (p = 0.0002) and the depth of tumor invasion (p = 0.001) was statistically significant. The high p27 expression group had a better prognosis than did the low or negative p27 expression groups, but these differences were not statistically significant. These observations may imply that a decrease in p27 expression occurs early on in the carcinogenesis of esophageal carcinoma. In addition, p27 expression may correlate with the histologic differentiation of squamous cell carcinoma of the esophagus.

Antibodies, Monoclonal↗

Effects of recombinant human macrophage colony-stimulating factor on atherosclerotic lesions established in the aorta of high cholesterol-fed rabbits.

Anti-atherosclerotic effects of human macrophage colony-stimulating factor were investigated using rabbits fed a high cholesterol diet. Rabbits fed a diet containing 2% cholesterol for 59 days developed hyperlipidemia and atheromatous aortic plaques. They were then administered 80 microg/kg/day of either macrophage colony-stimulating factor or human serum albumin, as a control, for the next 12 weeks. Compared with the control group, rabbits treated with macrophage colony-stimulating factor had significantly fewer plaques on the inner surface of the thoracic and abdominal aortae, and half the sectional area of thickened intima in the aortic arch, as well as in the thoracic and abdominal aortae. Macrophage colony-stimulating factor also decreased the cholesterol content of the atherosclerotic lesions. Serobiochemical analyses revealed that macrophage colony-stimulating factor increased the levels of high density lipoprotein-cholesterol significantly, without influencing other lipid parameters such as the level of low density lipoproteins. The effects of macrophage colony-stimulating factor were evident until the fourth week of drug injection, at which time anti-human macrophage colony-stimulating factor antibodies were clearly induced in the serum. These results indicate that exogenously administered macrophage colony-stimulating factor suppresses atherosclerotic lesions induced by a high cholesterol diet by activating lipid metabolism in vivo.

Animals↗