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Biomedical subjects

Hiroyuki Shimizu

Publications and source records attributed to Hiroyuki Shimizu.

At least 55 records · Page 3Linked to original sources
PubMed2005

A Sabin 3-derived poliovirus recombinant contained a sequence homologous with indigenous human enterovirus species C in the viral polymerase coding region.

Outbreaks of poliomyelitis caused by circulating vaccine-derived polioviruses (cVDPVs) have been reported in areas where indigenous wild polioviruses (PVs) were eliminated by vaccination. Most of these cVDPVs contained unidentified sequences in the nonstructural protein coding region which were considered to be derived from human enterovirus species C (HEV-C) by recombination. In this study, we report isolation of a Sabin 3-derived PV recombinant (Cambodia-02) from an acute flaccid paralysis (AFP) case in Cambodia in 2002. We attempted to identify the putative recombination counterpart of Cambodia-02 by sequence analysis of nonpolio enterovirus isolates from AFP cases in Cambodia from 1999 to 2003. Based on the previously estimated evolution rates of PVs, the recombination event resulting in Cambodia-02 was estimated to have occurred within 6 months after the administration of oral PV vaccine (99.3% nucleotide identity in VP1 region). The 2BC and the 3D(pol) coding regions of Cambodia-02 were grouped into the genetic cluster of indigenous coxsackie A virus type 17 (CAV17) (the highest [87.1%] nucleotide identity) and the cluster of indigenous CAV13-CAV18 (the highest [94.9%] nucleotide identity) by the phylogenic analysis of the HEV-C isolates in 2002, respectively. CAV13-CAV18 and CAV17 were the dominant HEV-C serotypes in 2002 but not in 2001 and in 2003. We found a putative recombination between CAV13-CAV18 and CAV17 in the 3CD(pro) coding region of a CAV17 isolate. These results suggested that a part of the 3D(pol) coding region of PV3(Cambodia-02) was derived from a HEV-C strain genetically related to indigenous CAV13-CAV18 strains in 2002 in Cambodia.

Cambodia↗
PubMed2005

Urinary cadmium and serum levels of estrogens and androgens in postmenopausal Japanese women.

BACKGROUND: Recent laboratory studies have suggested that cadmium is an estrogenic compound and may be a potential risk factor for breast cancer. METHODS: We investigated the relationship between urinary cadmium concentrations and serum concentrations of estrone, testosterone, and dehydroepiandrosterone sulfate in 164 postmenopausal Japanese women. RESULTS: There was a significant positive association between the urinary cadmium and serum testosterone levels after controlling for age and body mass index. The mean testosterone level was 28% higher in women with high urinary cadmium (> or = 3.00 microg/g creatinine) than in those with low urinary cadmium (< 2.00 microg/g creatinine). Urinary cadmium was not significantly associated with serum estrone and dehydroepiandrosterone sulfate levels. Additional adjustment for smoking, alcohol and reproductive factors including known risk factors for breast cancer did not substantially alter the results. CONCLUSION: Data suggested that cadmium exposure is associated with increased testosterone levels. As high testosterone levels have been associated with the risk of breast cancer, the involvement of cadmium exposure in breast cancer risk should be evaluated in future studies.

Aged↗
PubMed2005

Association of vegetable intake with urinary 6-sulfatoxymelatonin level.

Melatonin is present in plants consumed as vegetables; however, only a limited number of vegetables have been tested for melatonin. The antiproliferative, antioxidative, and immunostimulatory effects of melatonin have been reported from laboratory studies. The potential protective effects of vegetable against cancer and cardiovascular disease may be partially attributable to an increased melatonin intake from vegetables. As a first step to test this hypothesis, we evaluated whether vegetable intake is associated with an increased urinary melatonin in 289 community-dwelling Japanese women. Diet, including vegetable consumption, was assessed with a validated 169-item semiquantitative food-frequency questionnaire. Urinary 6-sulfatoxymelatonin (aMT6-s) was measured in the first-void morning urines. There was a significant positive association between vegetable intake and urinary aMT6-s levels. The mean urinary aMT6-s was 16% higher in women with the highest quartile of vegetable intake than it was in those with the lowest quartile of intake. This association may be explained by the melatonin contained in vegetables. However, data should be regarded as preliminary because it is impossible to estimate dietary melatonin intake from vegetables and or from the entire diet because of incomplete data for melatonin in plants.

Adult↗
PubMed2005

Associations of mammographic density with dietary factors in Japanese women.

BACKGROUND: A high percentage of mammographic dense area has been strongly associated with a risk of beast cancer. The present cross-sectional study evaluated the relations of percent density with dietary factors, such as fats, protein, dietary fiber, and soy isoflavones. METHODS: Study subjects were 601 (348 premenopausal and 253 postmenopausal) Japanese women who were recruited from a mammographic screening center. The size of the total breast area and the dense area were measured quantitatively using an automated mammographic mass detection method. Intakes of nutrients were estimated with a validated semiquantitative food-frequency questionnaire. RESULTS: The crude means of the percent density were 39.2% and 18.9% in premenopausal and postmenopausal women, respectively. There were no significant associations of any dietary factors with the percent density in premenopausal women. In postmenopausal women, percent density was significantly positively associated with intakes of protein, total fat, and saturated fat after controlling for covariates; the increase in the means of percent density were 7.2%, 5.6%, and 9.2% in the highest versus lowest quartile of intakes for protein, total fat, and saturated fat, respectively (P for linear trend were 0.006, 0.04, and 0.01, respectively). Carbohydrate intake was inversely associated with percent density; the mean of percent density was 6.0% lower in the highest versus the lowest quartile of intake (P(trend) = 0.03). The associations of dietary factors with dense area were very similar to those with percent density. CONCLUSION: These dietary factors may have implications for the risk of breast cancer in postmenopausal women.

Adult↗
PubMed2004

Fenofibrate, troglitazone, and 15-deoxy-Delta12,14-prostaglandin J2 close KATP channels and induce insulin secretion.

It is known that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligands stimulate acute-phase insulin secretion with a rapid Ca2+ influx into pancreatic beta-cells, but the precise mechanisms are not clear. The effects of PPAR-alpha ligands on pancreatic beta-cells also remain unclear. We investigated the effects of PPAR-alpha ligands (fenofibrate and fenofibric acid), a PPAR-gamma ligand (troglitazone), and an endogenous ligand of PPAR-gamma [15-deoxy-Delta12,14-prostaglandin J2 (15-deoxy-Delta12,14-PGJ2)] on KATP channel activity in clonal hamster insulinoma cell line, HIT-T15 cells. As assessed by whole-cell patch clamp, fenofibrate, fenofibric acid, troglitazone, and 15-deoxy-Delta12,14-PGJ2 reduced the KATP channel currents, and inhibition continued after washout of these agents. The concentration-response curves of fenofibrate, fenofibric acid, troglitazone, and 15-deoxy-Delta12,14-PGJ2 showed half-maximal inhibition of KATP channel currents (IC50) at 3.26, 94, 2.1, and 7.3 micromol/l, respectively. Fenofibrate (> or = 10(-6) mol/l), 15-deoxy-Delta12,14-PGJ2 (> or = 5 x 10(-5) mol/l), and troglitazone (> or = 10(-6) mol/l) inhibited [3H]glibenclamide binding, but fenofibric acid did not. In addition, fenofibrate (> or = 10(-6) mol/l), fenofibric acid (10(-4) mol/l), troglitazone (10(-4) mol/l), and 15-deoxy-Delta12,14-PGJ2 (> or = 10(-5) mol/l) increased insulin secretion from HIT-T15 when applied for 10 min. Our data suggest that PPAR-alpha and -gamma ligands interact directly with the beta-cell membrane and stimulate insulin secretion.

Animals↗
PubMed2004

Differential activation of epidermal growth factor (EGF) receptor downstream signaling pathways by betacellulin and EGF.

To determine the downstream signaling pathways regulated by betacellulin (BTC) in comparison with epidermal growth factor (EGF), we used Chinese hamster ovary cells overexpressing the human EGF receptor (ErbB1/EGFR). The overall time-dependent activation of EGFR autophosphorylation was identical in cells treated with 1 nm BTC or 1.5 nm EGF. Analysis of site-specific EGFR phosphorylation demonstrated that the BTC and EGF tyrosine phosphorylation of Y1086 was not significantly different. In contrast, the autophosphorylation of Y1173 was markedly reduced in BTC-stimulated cells, compared with EGF stimulation that directly correlated with a reduced BTC stimulation of Shc tyrosine phosphorylation, Ras, and Raf-1 activation. On the other hand, Y1068 phosphorylation was significantly increased after BTC stimulation, compared with EGF in parallel with a greater extent of Erk phosphorylation. Expression of a dominant interfering MEK kinase 1 (MEKK1) and Y1068F EGFR more efficiently blocked the enhanced Erk activation by BTC, compared with EGF. Interestingly BTC had a greater inhibitory effect on apoptosis, compared with EGF, and expression of Y1068F EGFR abolished this enhanced inhibitory effect. Together, these data indicated that although BTC and EGF share overlapping signaling properties, the ability of BTC to enhance Erk activation occurs independent of Ras. The increased BTC activation results from a greater extent of Y1068 EGFR tyrosine phosphorylation and subsequent increased recruitment of the Grb2-MEKK1 complex to the plasma membrane, compared with EGF stimulation. The increased Erk activation by BTC associated with antiapoptotic function.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Sodium intake and risk of death from stroke in Japanese men and women.

BACKGROUND AND PURPOSE: Despite the evidence for a positive association of dietary salt and blood pressure, the few prospective studies that have assessed the association between dietary salt and stroke have reported inconsistent results. The purpose of this study was to examine the relation between sodium intake and death from stroke in a population-based cohort of Japanese men and women. METHODS: In 1992, usual diet including sodium intake was determined in 13 355 men and 15 724 women in Takayama City, Gifu, with the use of a validated food frequency questionnaire. RESULTS: There were 269 stroke deaths (137 men and 132 women) between baseline and 1999. In men, the highest compared with the lowest tertile of sodium intake was significantly positively associated with death from total stroke after controlling for covariates (hazard ratio [HR]), 2.33; 95% CI, 1.23 to 4.45). Significantly positive associations were also observed between sodium intake and death from ischemic stroke (HR, 3.22; 95% CI, 1.22 to 8.53) as well as death from intracerebral hemorrhage (HR, 3.85; 95% CI, 1.16 to 12.7). A positive association between sodium intake and death from stroke in women was suggested, although the associations for total stroke and ischemic stroke were of borderline significance (HR, 1.70; 95% CI, 0.96 to 3.02 and HR, 2.10; 95% CI, 0.96 to 4.62, respectively). CONCLUSIONS: These prospective data support the hypothesis that dietary salt increases the risk of death from stroke.

Cohort Studies↗
PubMed2004

Circulating vaccine-derived polioviruses: current state of knowledge.

Within the past 4 years, poliomyelitis outbreaks associated with circulating vaccine-derived polioviruses (cVDPVs) have occurred in Hispaniola (2000-01), the Philippines (2001), and Madagascar (2001-02). Retrospective studies have also detected the circulation of endemic cVDPV in Egypt (1988-93) and the likely localized spread of oral poliovirus vaccine (OPV)-derived virus in Belarus (1965-66). Gaps in OPV coverage and the previous eradication of the corresponding serotype of indigenous wild poliovirus were the critical risk factors for all cVDPV outbreaks. The cVDPV outbreaks were stopped by mass immunization campaigns using OPV. To increase sensitivity for detecting vaccine-derived polioviruses (VDPVs), in 2001 the Global Polio Laboratory Network implemented additional testing requirements for all poliovirus isolates under investigation. This approach quickly led to the recognition of the Philippines and Madagascar cVDPV outbreaks, but of no other current outbreaks. The potential risk of cVDPV emergence has increased dramatically in recent years as wild poliovirus circulation has ceased in most of the world. The risk appears highest for the type 2 OPV strain because of its greater tendency to spread to contacts. The emergence of cVDPVs underscores the critical importance of eliminating the last pockets of wild poliovirus circulation, maintaining universally high levels of polio vaccine coverage, stopping OPV use as soon as it is safely possible to do so, and continuing sensitive poliovirus surveillance into the foreseeable future. Particular attention must be given to areas where the risks for wild poliovirus circulation have been highest, and where the highest rates of polio vaccine coverage must be maintained to suppress cVDPV emergence.

Child↗
PubMed2004

Lifetime and 6-month prevalence of DSM-III-R psychiatric disorders in an urban community in Japan.

We conducted a community-based interview survey of a random sample of residents aged 20 years or older in an urban community in Japan using the University of Michigan Version of the WHO Composite International Diagnostic Interview for selected mood and anxiety disorders and alcohol abuse/dependence according to DSM-III-R. The final sample consisted of 1029 respondents (response rate, 57%). The lifetime and 6-month prevalences of selected mood, anxiety and alcohol use disorders were low in general. Alcohol abuse/dependence was more prevalent in men than in women. Younger respondents had a greater risk of generalized anxiety disorder and alcohol dependence. A greater risk of mood, anxiety and alcohol use disorders was observed among a recent birth cohort. We confirmed a lower prevalence of mood and anxiety disorders and alcohol use disorders in a community population in Japan than in Western countries, observations that were similar to previous ones in East-Asian countries. The patterns of demographic correlates and comorbidity are similar to those of most other countries.

Adult↗
PubMed2004

Cancer-related attitudes: A comparative study in Japan and the US.

The cancer-related attitudes and beliefs of adults living in central Japan (N = 357) were compared to those of respondents in a US state (Hawaii) (N = 223) consisting of both Japanese (n = 106) and Caucasian (n = 117) individuals. Almost all US subjects endorsed doctors disclosing cancer diagnoses to their patients, while a minority of the Japan sample supported cancer disclosure as a general practice. However, the majority of Japan respondents expressed a personal preference to be told if they themselves were diagnosed with cancer, as did virtually all US respondents. US subjects were more optimistic than Japanese subjects about cancer's curability, both at the present time and in the future; Japanese Americans scored intermediate between Japanese and Caucasian Americans. Word-association data indicated that cancer was most likely to be associated with death by Japanese respondents. The data support the continued international differences in views about cancer and suggest that some of these differences persist over many generations of US residence.

Adult↗
PubMed2004

Theta oscillation in the human anterior cingulate cortex during all-night sleep: an electrocorticographic study.

Ten epileptic patients each with subdural electrodes surgically attached to the anterior cingulate cortex (ACC; two cases), the orbitofrontal cortex (OFC; seven cases), or both (one case) were included in this study. We recorded each patient's ACC or OFC electrocorticogram (ECoG) during the time period that the patient was awake and naturally asleep. We performed a Fast Fourier Transformation (FFT) power spectral analysis on each ECoG to examine its frequency component. We found that the ACC showed regular and continuous theta oscillation (5-7Hz) during wakefulness and rapid eye movement (REM) sleep, but not during slow wave sleep. Theta waves observed in REM sleep were not as distinct as those found in wakefulness. We also discovered that the orbitofrontal signals represented spectral peaks in the theta band only during wakefulness. This suggests the coexistence of theta oscillation in the ACC. Considering our previous observations of gamma and beta oscillations in the human hippocampus, we hypothesize that the human limbic system manifests two oscillatory activities. The results obtained in this study suggest that electrophysiological activity in the ACC could be related to particular psychological functions in wakefulness and in REM sleep. These results are useful in elucidating the human brain mechanism.

Adult↗