Biomedical subjects

Tomohiro Saito

Publications and source records attributed to Tomohiro Saito.

9 recordsLinked to original sources

PubMed2006

Childhood leukemia and magnetic fields in Japan: a case-control study of childhood leukemia and residential power-frequency magnetic fields in Japan.

Residential power-frequency magnetic fields (MFs) were labeled as a possible human carcinogen by the International Agency for Research on Cancer panel. In response to great public concern, the World Health Organization urged that further epidemiologic studies be conducted in high-exposure areas such as Japan. We conducted a population-based case-control study, which covered areas inhabited by 54% of Japanese children. We analyzed 312 case children (0-15 years old) newly diagnosed with acute lymphoblastic leukemia (ALL) or acute myelocytic leukemia (AML) in 1999-2001 (2.3 years) and 603 controls matched for gender, age and residential area. Weekly mean MF level was determined for the child's bedroom. MF measurements in each set of a case and controls were carried out as closely in time as possible to control for seasonal variation. We evaluated the association using conditional logistic regression models. The odds ratios for children whose bedrooms had MF levels of 0.4 microT or higher compared with the reference category (MF levels below 0.1 microT) was 2.6 (95% CI=0.76-8.6) for AML+ALL and 4.7 (1.15-19.0) for ALL only. Controlling for some possible confounding factors did not alter the results appreciably. Even an analysis in which selection bias was maximized did not fully explain the association. Most of the leukemia cases in the highest exposure category had MF levels far above 0.4 microT. Our results provided additional evidence that high MF exposure was associated with a higher risk of childhood leukemia, particularly of ALL.

Acute Disease↗

PubMed2005

No advantage of dexamethasone over prednisolone for the outcome of standard- and intermediate-risk childhood acute lymphoblastic leukemia in the Tokyo Children's Cancer Study Group L95-14 protocol.

PURPOSE: To evaluate whether dexamethasone (DEXA) yields a better outcome than prednisolone (PRED) in a prospective, randomized, controlled trial for the treatment of childhood acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Two hundred thirty-one standard-risk (SR) patients and 128 intermediate-risk (IR) non-B-cell ALL patients were registered from March 1995 to March 1999. After random assignment in each group, the PRED arm patients received PRED 60 mg/m2 during induction followed by PRED 40 mg/m2 over four intensifications in the SR group and three intensifications in the IR group. DEXA arm patients received DEXA 8 mg/m2 during induction and DEXA 6 mg/m2 during the intensifications. The maintenance phase was continued until week 104. RESULTS: Event-free survival rates at 8 years in the DEXA and PRED arms were 81.1% +/- 3.9% (n = 117) and 84.4% +/- 5.2% (n = 114), respectively, in the SR group (P = .217) and 84.9% +/- 4.6% (n = 62) and 80.4% +/- 5.1% (n = 66), respectively, in the IR group (P = .625). The primary reason for treatment failure was marrow relapse. Only two extramedullary relapses occurred in the DEXA arm compared with seven relapses in the PRED arm. Although complications were more prevalent in the DEXA arm than in the PRED arm, fatal toxicity was rare both groups. CONCLUSION: DEXA administered at 8 mg/m2 during induction and 6 mg/m2 during intensification showed no advantage over PRED administered at 60 mg/m2 during induction and 40 mg/m2 during intensification in both the SR and IR groups.

Child↗

PubMed2005

Surfactant-based homogeneous assay for the measurement of triglyceride concentrations in VLDL and intermediate-density lipoprotein.

BACKGROUND: Existing studies have demonstrated the clinical significance of triglyceride content in VLDL (VLDL-TG) and intermediate-density lipoprotein (IDL-TG). We developed a homogeneous assay protocol to directly measure VLDL-TG. METHODS: Possible reagents and conditions for measuring VLDL-TG were comprehensively tested, and the "best" combination was determined. Healthy persons were instructed to consume a fatty meal after 15-h overnight fasting. Serum VLDL-TG + IDL-TG concentrations were measured using the proposed method. Patients with serum LDL-cholesterol concentrations > or = 3.62 mmol/L (140 mg/dL) were administered simvastatin at a daily dose of 5 mg, and serum VLDL-TG concentrations were then measured. RESULTS: The combination of 2 nonionic surfactants played an important role in differentiating VLDL and IDL from other lipoproteins, probably via specific interactions with phospholipids and apolipoproteins. The regression line of the proposed method (y) and the ultracentrifugal assay (x) was: y = 0.98x + 0.31 mmol/L (r = 0.98; n = 73; P < 0.05). The difference between postprandial total TG and VLDL-TG concentrations was statistically significant (P < 0.05). After 8 weeks of therapy with simvastatin, total TG and LDL-cholesterol concentrations were 13.6% and 26.3% lower, respectively (P < 0.05), whereas VLDL-TG did not show any significant decrease. CONCLUSION: Our homogeneous method can measure TG content in VLDL and IDL.

Adult↗

PubMed2005

Amplitude-division three-electron-wave interference for observing pure phase objects having low spatial frequency.

A new interferometry is presented for direct visualization of pure phase objects having low spatial frequency, such as electromagnetic microfields. A thin crystal of silicon prepared using argon ion milling is installed at the standard specimen position. This silicon crystal works as an electron beam splitter and forms diffraction spots in the back focal plane. Using the objective aperture, [000], [111] and [111] spots are selected as coherent electron sources to illuminate the specimen located at the area-selecting aperture position. The lattice image of silicon is formed below the area-selecting aperture position by decreasing the electric current of the objective lens. Three defocused images of the specimen are observed in the fluorescent screen by overexciting the first intermediate lens. We have successfully visualized equipotential lines around a latex particle charged by electron beam irradiation. The computer-simulated image was consistent with the experimental image.

Journal Article↗

PubMed2004

Potential errors resulting from sex and age difference in assessing family history of coronary heart disease.

BACKGROUND: Coronary heart disease occurs nearly exponentially with age and differently between men and women. Therefore, difference in sex and age of family members yields errors in assessing the family history as a risk factor. The influence of sex and age on the positivity of family history was assessed numerically. METHODS: Through questionnaires filled in by the parents of 2316 high school students, information was obtained on the past history of coronary heart disease among students' parents, grandparents, uncles, and aunts. The sex- and age-specific proportion of a positive history was calculated from the past history among the 24,071 family members. The influence of sex and age on a positive history was estimated as odds ratios by logistic regression analysis of the past history. RESULTS: The odds ratios obtained for sex and age difference were 1.61 (95% confidence interval: 1.42-1.83) and 1.07 (95% confidence interval: 1.06-1.07), respectively. This indicated that a positive history was 1.61 times higher among male members than among female members of the same age, and that a positive history increased by (1.07)y, where y was age difference by year. CONCLUSIONS: Potential errors resulting from disregarding the sex and age of family members can be substantial, judging from the above numerical figures. Some measures to control for the sex and age of family members are required in assessing family history of coronary heart disease.

Adult↗

PubMed2004

[Retinopathy of prematurity in extremely low birth weight infants: a Tokyo multicenter study].

OBJECTIVE: To investigate how the increase in survival rate in extremely low birth weight (a birth weight of 1,000 g or less) infants had affected the incidence of retinopathy of prematurity (ROP) and the frequency of laser treatment. METHODS: We retrospectively reviewed the medical records of 122 surviving premature infants with birthweights less than 1,000 g to determine the severity of ROP observed at 16 neonatal intensive care units in Tokyo between April and October 2002. RESULTS: The survival rate was 85.6%. The mean gestational age was 26.74 weeks and the mean birth weight was 782.25 g. One-hundred-and-five infants (86.1%) developed ROP, fifty (41.0%) received laser treatment, and six (4.9%) had retinal detachment. The median postmenstrual age (gestational age at birth plus chronological age in weeks, PMA) at the onset of ROP was 32.5 weeks, and the first laser treatment was performed at the median PMA of 35.7 weeks. CONCLUSIONS: In these extremely low birth weight infants, there was an increase in the survival rate and in the incidence of severe ROP that progressed to the stage that required treatment.

Birth Weight↗

PubMed2002

A dose-response relationship between short sleeping hours and childhood obesity: results of the Toyama Birth Cohort Study.

BACKGROUND: Short sleeping hours could cause obesity through increased sympathetic activity, elevated cortisol secretion and decreased glucose tolerance. The aim of this study was to clarify parental and lifestyle factors, particularly sleeping habits, associated with obesity in Japanese children. METHODS: Between June and July 1996, 8274 children (4194 males and 4080 females) aged 6-7 years living in Toyama prefecture, Japan, were investigated by questionnaire survey and the collection of anthropometric data. Subjects with a body mass index (BMI; weight in kg divided by square of height in m) greater than the age- and sex-specific cut-off points linked to adulthood overweight (BMI of 25 kg/m2 or more) were defined as obese subjects. Parental obesity was defined as a BMI of 25 kg/m2 or more. Logistic regression analysis was performed to evaluate the strength of the relationships between parental obesity or lifestyle factors and childhood obesity, adjusted for possible confounding factors. RESULTS: Parental obesity, long hours of TV watching and physical inactivity were significantly associated with childhood obesity. Although wake-up time was not related to obesity, there was a significant dose-response relationship between late bedtime or short sleeping hours and childhood obesity. Compared with children with 10 or more hours of sleep, the adjusted odds ratio was 1.49 (95% confidence interval 1.08-2.14) for those with 9-10 h sleep, 1.89 (1.34-2.73) for those with 8-9 h sleep and 2.87 (1.61-5.05) for those with <8 h sleep, after adjustment for age, sex, parental obesity and other lifestyle factors. CONCLUSION: A strong inverse association was observed in the relationship between sleeping hours and childhood obesity. Longitudinal research will be required to confirm this causality.

Anthropometry↗

PubMed2002

Combined use of hyperthermia and irradiation cause antiproliferative activity and cell death to human esophageal cell carcinoma cells--mainly cell cycle examination.

In clinically hyperthermia and irradiation therapy for malignant neoplasms are known that they have antiproliferative activity and cell death (including apoptosis) inducing activity. However not only mechanisms of cell death induction but treatment effects of them still have been unclear. In this time we showed that cell cycles from G0/G1 phase to S-G2/M phase were delayed by hyperthermia and G2/M phase accumulation were caused immediately by irradiation. And we also demonstrated that the combination treatments of hyperthermia and irradiation induced synergistic antiproliferative effects and strong effects of cell death to human esophageal carcinoma cell lines. Although treatments of hyperthermia and irradiation were mild individually, combination treatment of hyperthermia and irradiation were useful for esophageal carcinoma treatment.

Adult↗

PubMed2002

Parental obesity, lifestyle factors and obesity in preschool children: results of the Toyama Birth Cohort study.

The aim of this study was to clarify the impact of parental obesity and lifestyle factors on obesity in preschool children. The subjects consisted of 8941 children aged 3 years, born in 1989. Anthropometric measurements and questionnaire surveys were conducted between 1992 and 1994. Subjects of body mass index (BMI; (weight (kg))/(height (m))2) more than the age- and sex-specific centiles linked to adult overweight were defined as obese subjects. Parental obesity was defined as BMI of 25 kg/m2 or more. Logistic regression analysis was performed to clarify the strengths of parental and lifestyle factors on childhood obesity, adjusted for possible confounding factors. Odds ratios (ORs) of paternal and maternal obesity for childhood obesity were 1.70(1.43-2.02) and 2.56(2.07-3.17), respectively. There was a dose-response relationship between short sleeping hours and obesity. Compared to subjects taking 11 hours sleep or more, the adjusted OR was 1.20(0.97-1.49) for those taking 10 to 11 hours sleep, 1.34(1.05-1.72) for those taking 9 to 10 hours sleep, and 1.57(0.90-2.75) for those taking less than 9 hours sleep. Eating and exercising habits were not significantly associated with obesity. These results indicate that parental obesity and short sleeping hours are possible risk factors for obesity in preschool children.

Adult↗