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Biomedical subjects

Hiroshi Koyama

Publications and source records attributed to Hiroshi Koyama.

At least 19 recordsLinked to original sources

A retrospective review of 226 hospitalized patients with fever.

OBJECTIVE: To describe characteristics and outcomes for patients hospitalized with fever, not only patients with fever of unknown origin (FUO). METHODS: Medical records were reviewed for 226 consecutive patients hospitalized in a Japanese referral hospital with fever as one of the clinical problems. RESULTS: Although the majority of illnesses involved some sort of infection (54%), noninfectious inflammatory diseases, particularly adult Still's disease (n=6) and primary vasculitis syndromes (n=5) including 3 cases of Behçet's disease, represented the leading cause in patients who met the definition of FUO [16/51(31%)]. Tuberculosis (n=6) and psychological disorders (n=6) were associated with late diagnosis. However, there was only one patient meeting the definition of FUO among those with a psychological disorder. Among the patients with prolonged fever who did not strictly meet the definition of FUO, there was a considerable number of patients with critical illnesses, such as intra-abdominal abscess, polymyalgia rheumatica, sarcoidosis, ulcerative colitis, Castleman's disease, hematological and solid malignancies, and panhypopituitarism. Drug-induced fever, systemic viral infection and unspecified vasculitis were difficult to definitively diagnose, although these pathologies were suspected as causes of fever. Follow-up of patients without definitive diagnosis at discharge confirmed that the fever subsided spontaneously or the cause of fever was properly treated after diagnosis in every patient and that none died of the underlying febrile illness. CONCLUSIONS: The present findings, from all patients displaying fever at hospitalization, are in agreement with findings from prior FUO series. Strict use of the definition of FUO is thus unwarranted when managing patients with prolonged fever.

Adult↗

Total body propofol clearance (TBPC) after living-donor liver transplantation (LDLT) surgery is decreased in patients with a long warm ischemic time.

Metabolic capacity after liver transplant surgery may be affected by the graft size and by hepatic injury during the surgery. This study was carried out to investigate the postoperative total body propofol clearance (TBPC) in living-donor liver transplantation (LDLT) patients and to investigate the major factors that contribute to decreased postoperative TBPC in LDLT patients. Fourteen patients scheduled for LDLT were included in this study. Propofol was administered at a rate of 2.0 mg.kg(-1).h(-1) as a sedative in the intensive care unit (ICU) setting. To calculate TBPC, propofol arterial blood concentration was measured by HPLC. Five variables were selected as factors affecting postoperative TBPC; bleeding volume (BLD), warm ischemic time (WIT), cold ischemic time (CIT), graft weight/standard liver volume ratio (GW/SLV), and portal blood flow after surgery (PBF). After factor analysis of six variables, including TBPC, varimax rotation was carried out, and this yielded three interpretable factors that accounted for 75.5% of the total variance in the data set. TBPC, WIT, CIT, and BLD were loaded on the first factor, PBF on the second factor, and GW/SLV on the third factor. The adjusted correlation coefficient between TBPC and WIT showed the highest value (r = -0.61) in the first factor. The LDLT patients were divided into two groups according to WIT; group A (WIT > 100 min) and group B (WIT < 100 min). Mean TBPC values in group A and group B were 14.6 +/- 2.1 and 28.5 +/- 4.1 ml.kg(-1).min(-1), respectively (P < 0.0001). These data suggest that LDLT patients with a long WIT have a risk of deteriorated drug metabolism.

Adolescent↗

Mixed germinoma and choriocarcinoma in the intramedullary spinal cord: case report and review of the literature.

Primary germinomas in the spinal cord are very rare with only 15 cases published previously. In this case a 22-year-old woman with urinary incontinence, lumbago, and bilateral leg pain and weakness was found to have a solid tumor in the conus medullaris between the L1 and L2 vertebral bodies. Serum HCG was elevated without pregnancy. The pathological diagnosis was mixed germinoma and choriocarcinoma of the intramedullary spinal cord. She received craninospinal irradiation and three courses of chemotherapy and is currently asymptomatic with no evidence of recurrence and metastasis 22 months after surgery. To our knowledge, this is the first case report of a patient with a primary mixed germinoma and choriocarcinoma of the intramedullary spinal cord. The previous 15 cases of primary spinal cord germinoma have been reviewed for comparison.

Adult↗

Selenium supplementation and blood rheological improvement in Japanese adults.

In order to study the prevention effect of selenium in the development of cardiovascular disease, we investigated the effects of selenium supplementation on the blood rheological properties. Eleven healthy adults were administered with 200 microg of selenium in the form of selenium yeast per day for 1 wk. Before and after the supplementation, serum selenium concentration, glutathione peroxidase (GPx) activity, biochemical indices, and the blood fluidity of the subjects were measured. The blood fluidity was measured using a (microchannel array flow analyzer) by the passage time of 100 microL of heparinized whole blood through the microchannel array. The selenium supplementation significantly (p = 0.001) shortened the mean blood passage time from 44.0 +/- 5.7 to 37.5 +/- 2.8 s. Serum selenium concentration significantly (p = 0.008) increased from 109.8 +/- 10.2 to 124.5 +/- 16.7 microg/L. Meanwhile, the GPx activity did not increased significantly (p = 0.058). The mean GPx activity of the subjects before supplementation was 171.0 +/- 16.1 Deltammol NADPH/min/L and 180.9 +/- 17.8 Deltammol NADPH/min/L after supplementation. Factor analysis of the passage time and biochemical indices of the subjects showed that blood fluidity improvement was related to the metabolic modification of lipoproteins during the selenium supplementation. These results showed that selenium supplementation improved the blood fluidity, without increasing the GPx activity of the subjects.

Adult↗

Medical student abuse during clinical clerkships in Japan.

OBJECTIVE: To assess the prevalence of medical student abuse during clinical clerkships in Japan. DESIGN: A cross-sectional questionnaire survey. SETTING: Six medical schools in Japan. PARTICIPANTS: Final year (sixth-year) and fifth-year medical students in the period from September 2003 to January 2004. From a total of 559 students solicited, 304 (54.4%) returned the questionnaire, and 276 (49.4%: 178 male and 98 female) completed it. MEASUREMENTS: Prevalence of medical student abuse in 5 categories: verbal abuse, physical abuse, academic abuse, sexual harassment, and gender discrimination; differences in abusive experience between male and female students; types of alleged abusers; reporting abusive experiences to authorities; and emotional effects of abusive experiences. RESULTS: Medical student abuse was reported by 68.5% of the respondents. Verbal abuse was the most frequently experienced abuse (male students 52.8%, female students 63.3%). Sexual harassment was experienced significantly more often (P<.001) by female students (54.1%) than by male students (14.6%). Faculty members were most often reported as abusers (45.2% of cases). Abuse occurred most frequently during surgical rotations (42.0% of cases), followed by internal medicine (25.1%) and anesthesia rotations (21.8%). Very few abused students reported their abusive experiences to authorities (8.5%). The most frequent emotional response to abuse was anger (27.1% of cases). CONCLUSIONS: Although experience of abuse during clinical clerkships is common among medical students in Japan, the concept of "medical student abuse" is not yet familiar to Japanese. To improve the learning environment, medical educators need to take action to resolve this serious issue.

Cross-Sectional Studies↗

Chemical forms of selenium for cancer prevention.

Cancer is becoming an increasingly significant disease worldwide. Currently, more than 7 million people die each year from cancer. With the existing knowledge, at least one-third of worldwide cancer cases could be prevented. Searching for naturally occurring agents in routinely consumed foods that may inhibit cancer development, although challenging, constitutes a valuable and plausible approach to the control and prevention of cancer. To date, the use of the micronutrient selenium (Se) in human clinical trials is limited, but the outcome indicates that Se is among the most promising agents. Although it is convenient to describe the effects of Se in terms of the element, it must always be kept in mind that the chemical form of Se and the dose are determinants of its biological activities. Hyphenated techniques based on coupling chromatographic separation with inductively coupled plasma mass spectrometric (ICP-MS) detection are now established as the most realistic and potent analytical tools available for real-life speciation analysis. These speciation investigations provide evidence that the Se compounds, which can generate monomethylated Se (e.g., Se-methylselenocysteine and methylseleninic acid), are more efficacious than other Se compounds because of their chemoprevention activity.

Anticarcinogenic Agents↗

Longitudinal changes in patient vs. physician-based outcome measures did not significantly correlate in asthma.

BACKGROUND AND OBJECTIVE: Although improving health status is one important aim in managing asthmatic patients, few studies have evaluated their health status longitudinally. Therefore, we examined longitudinal changes in health status of asthma patients, and compared them with changes in physiological measures. METHODS: Eighty-seven outpatients with stable asthma after 6 months of treatment were recruited. Health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ), pulmonary function, peak expiratory flow (PEF) values, and airway hyperresponsiveness (AHR) were evaluated at entry and every year over a 5-year period. RESULTS: Using mixed effects models to estimate the slopes, the overall AQLQ score declined statistically at a mean rate of 0.06 units/year (P=.0091). However, this decline did not reach a clinically significant level at 5 years. The total SGRQ score did not change significantly (P=.54). Although the forced expiratory volume in 1 sec declined at a mean rate of 53 mL/year, the PEF variability and AHR improved significantly. CONCLUSION: Health status was clinically stable over the 5-year study period in patients with asthma, which contrasted with the changes in the physiological outcome measures. As a patient centered outcome measure, health status should be followed separately.

Administration, Inhalation↗

Low contribution of rice and vegetables to the daily intake of selenium in Japan.

The growing interest in the prevention role of selenium in certain degenerative diseases such as cancer and cardiovascular disease has fostered research on natural sources of selenium. In this research, total selenium concentrations in over 120 items of selected Japanese foods were determined. The selenium concentration was measured fluorometrically by measurement of the fluorescence of piazselenol resulting from the reaction of selenite with 2, 3-diaminonaphtalene. The selenium level in rice, which is the staple food consumed in Japan, is lower than the other countries. But the mean levels of selenium in meat and fish products are among the highest values reported in other countries. Although the numbers of samples of selected foods analyzed are small, the results describe the picture of the selenium level of Japanese foods.

Food Analysis↗

Participation of Rho-dependent transcription termination in oxidative stress sensitivity caused by an rpoB mutation.

The role of transcription termination process for gene expression regulation is poorly understood. Either a multicopy supply of the rof gene or bicyclomycin, both of which inhibit the transcription termination Rho factor, suppressed the increased sensitivity to oxidative stress of the rifampicin-resistant rpoB mutation in Escherichia coli. Multi-copy supply of the rnk gene also suppressed oxidative stress sensitivity, coincident with the recovery of the reduced concentration of nucleoside triphosphates in the mutant cells, which is one of the factors that affects transcription termination efficiency in vitro. Thus, an appropriate, nonexcessive termination frequency at Rho-dependent transcription terminators might contribute to oxidative stress survival. Clinical application of oxidative stress against drug resistant bacteria is also discussed.

DNA-Directed RNA Polymerases↗

Concentrations of copper and zinc in liver and serum samples in biliary atresia patients at different stages of traditional surgeries.

Many patients with biliary atresia (BA) have impaired metabolism of copper (Cu) and zinc (Zn) because of the obstruction of bile ducts. An excessive Cu accumulation is cytotoxic and results in fibrosis in hepatic tissues. Since Zn works antagonistically to Cu, lower Zn concentrations may deteriorate liver damage. In the 1980's, we performed a series of surgeries on BA patients for the construction and alteration of the bile flow route, which is the major excretion route for Cu. We obtained liver and serum samples at each surgery, and measured Cu and Zn concentrations by inductively coupled plasma atomic emission spectrometry. Hepatic Cu concentration decreased with the improvement of cholestasis after the establishment of bile excretion. Conversely, when cholestasis persisted or recurred, increases in hepatic and serum Cu concentrations were noted. Hepatic Zn concentration was lower than previously reported normal values. High hepatic and serum Cu concentrations due to persistent or recurrent cholestasis and low hepatic Zn concentration may deteriorate hepatic fibrosis and liver cirrhosis.

Biliary Atresia↗

Perceived health as related to income, socio-economic status, lifestyle, and social support factors in a middle-aged Japanese.

BACKGROUND: Few studies have examined the association of perceived health with socio-economic status, especially income, and social isolation and support in Japan. The purpose of this study is to clarify the associations among perceived health, lifestyle, and socio-economic status, as well as social isolation and support factors, in middle-aged and elderly Japanese. METHODS: Subjects were 9,650 participants aged 47-77 years who completed a self-administered questionnaire in 2000 in the second survey of a population-based cohort (the Komo-Ise study). The questionnaire included items on sociodemographic and socio-economic factors, social isolation and support, lifestyle, past history of chronic disease and perceived health. Perceived health was dichotomized into excellent or good health and fair or poor health. A logistic regression analysis was used to determine the odds ratios of socio-economic status, social characteristics and lifestyle in relation to self-reported fair or poor health. RESULTS: We found that household income, physical activity, sleeping, smoking habit, and BMI had a strong association with self-reported fair or poor health in middle-aged and elderly Japanese men and women. Male subjects tended to report fair or poor health as household income decreased. The results for women differed in that social isolation and low social support had a stronger association for self-reported fair or poor health than low household income. CONCLUSIONS: The results indicated that perceived health was associated with socio-economic and social characteristics among middle-aged and elderly residents in Japan.

Aged↗

Body mass index and mortality in a middle-aged Japanese cohort.

BACKGROUND: The relative risk of mortality in low and high body mass index (BMI) categories in various ethnic groups remains a controversial subject. METHODS: To examine the relationship between BMI and mortality, a population-based prospective cohort study was conducted in two areas of Gunma Prefecture, Japan, in 1993. A total of 5,554 men and 5,827 women aged 40-69 years completed a self-administered questionnaire and were followed up until the year 2000. The hazard ratios (HRs) were estimated by the Cox proportional hazards model for different BMI classes. RESULTS: During the seven year follow-up period, 329 men and 147 women died. As compared with those in the reference BMI category (22.0-24.9 kg/m(2)), men and women in the lowest BMI category (<18.5 kg/m(2)) had a HR (95% confidence interval [CI]) of death from all-causes of 2.66 (1.59-4.46) and 3.14 (1.38-7.13), respectively, and women in the highest BMI category (28.0+ kg/m(2)) had a HR of death of 3.25 (1.48-7.15), after adjusting for all possible confounding factors including smoking and after excluding deaths occurring during the first three years of follow-up. CONCLUSION: In this prospective study of a Japanese cohort consisting of subjects ranging in age from 40 to 69 years, the curve depicting the relationship between BMI and all-cause mortality was L-shaped in men and U-shaped in women.

Adult↗

Effects of timing of thoracoscopic surgery for primary spontaneous pneumothorax on prognosis and costs.

BACKGROUND: Primary spontaneous pneumothorax recurs frequently. Timing of video-assisted thoracoscopic surgery to prevent recurrence is controversial and long-term costs remain inconclusive. METHODS: We constructed a Markov model to assess the effect of different timings for surgery on health status, costs, and cost effectiveness from the payers' perspective in Japan. RESULTS: During 1-year follow-up, the proportions of patients who underwent surgery after the first and second drainage were 46% and 36%, respectively. Average 1-year cost for surgery at the first episode was highest (U.S. dollars 6556), followed by the second (U.S. dollars 2988) and the third (U.S. dollars 2532). Incremental cost for surgery at the first episode compared with the second and that at the second episode compared with the third were U.S. dollars 30564 and U.S. dollars 29915 per quality-adjusted life year, respectively. Sensitivity analyses showed utility and length of hospital stay for surgery have the strongest effect on incremental cost. CONCLUSIONS: Thoracoscopic surgery at the first episode significantly increased costs, but could be acceptable from a cost-effectiveness perspective.

Adult↗

Dietary habits and selenium intake of residents in mountain and coastal communities in Japan.

We used a Simple Food Frequency Questionnaire (SFFQ) in combination with other dietary approaches to estimate the selenium intake from different food groups based on the average long-term diet, in two rural communities in Japan, one in a mountain area and the other in a coastal area. The intake frequencies of rice and wheat products were significantly different in the two districts. The intake frequencies of fish, meat, and eggs, which are rich in selenium, were not significantly different. The mean dietary selenium intake, estimated from the SFFQ and the 24-h recall method, was 82.7 microg/d (n=234) (range 19.2-180.1 microg/d) in the mountain community. The mean dietary selenium intake estimated from the SFFQ and average value of the normal portion size was 118.0 microg/d (n=123) (range 22.6-255.3 microg/d) in the coastal community. These estimated mean values exceeded the Japanese RDA, although the range of daily selenium intake was large. In the mountain community, fish made the largest contribution to dietary selenium intake (48.2% of daily total), followed by eggs (24.3%), and meat (17.0%). In the coastal community, fish accounted for 57.7% of daily total selenium intake, followed by meat (17.5%), and eggs (16.1%). In both districts, the total contribution of rice and wheat products was around 10%. It was found that the contribution of fish to dietary selenium intake was high and the contribution of cereals was low among Japanese.

Adult↗

Encephalopathy in megacystis-microcolon-intestinal hypoperistalsis syndrome patients on long-term total parenteral nutrition possibly due to selenium deficiency.

This report concerns two patients (female, 9 and 6 years) who were diagnosed with megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). Although they exceeded the usual life expectancy of patients diagnosed with MMIHS because of total parenteral nutrition (TPN), they demonstrated progressive neurological deficits and showed histopathological features in the brain. Both patients were diagnosed with MMIHS in the neonatal period and were fed by TPN. The first patient developed visual and gait disturbances at the age of 7 years. Two months later, she developed dysarthria and muscular weakness, and could not maintain her posture. The level of serum selenium was extremely low. The second patient developed flexion and spasticity of the extremities followed by decorticate posture at the age of 3 years. Both patients died of sepsis. The brain weights of the two cases were 880 g and 715 g. In both cases, severe neuronal loss and gliosis were present in the medial convolutions of the occipital lobe, including the visual cortex. The postcentral gyrus and temporal transverse gyrus were also involved. In addition, extensive loss of Purkinje cells and granular neurons, and gliosis were observed in the cerebellum. We measured the selenium content of the brains and livers using the graphite furnace atomic absorption spectrometry method. Selenium was not detected in either brain, although the livers of both cases contained a low level of selenium. On immunohistochemical examination of the anti-oxidative enzymes, histiocyte-macrophage lineage cells in MMIHS cases, including microglia and Kupffer cells, showed only a weak reaction for glutathione peroxidase, of which selenium is an essential component. However, the cells in the control cases were strongly positive. In cases of MMIHS and methylmercury intoxication, the brain features similar lesions, in both their topographical and histopathological aspects. We considered that the brain lesions of the MMIHS patients mainly resulted from oxidative damage of the brain related to the low levels of glutathione peroxidase and other selenoproteins due to selenium deficiency.

Abnormalities, Multiple↗