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Biomedical subjects

Z Yamagata

Publications and source records attributed to Z Yamagata.

27 records · Page 2Linked to original sources
PubMed1995

[Effect of vitamin D receptor gene polymorphism and lifestyle on bone mineral density and bone mineral density decrement rate].

The effects of genetic and environmental factors on bone mineral density (BMD) were investigated in 108 healthy Japanese women. Of the 108 subjects, BMD (from the second to forth lumbar vertebrae) was measured in 1992 in 103, in 1993 in 100, and in both years in 95 by dual energy X-ray absorptiometry. Vitamin D receptor (VDR) gene polymorphism in intron 8 was used as a genetic marker. Information on menstruation, health status, lifestyle, quantities of nutrient intake and frequencies of food intake was obtained by questionnaire. The frequency of allele B (825bp), whose polymerase chain reaction (PCR) products cannot be cut with BsmI, was 0.259 and the frequency of allele b (650bp), whose PCR products can be cut with BsmI, was 0.741. The subjects in our study obeyed the Hardy-Weinberg law. While the frequency of allele B was 0.448 in European whites as reported by Morrison et al, it was 0.259 in our Japanese subjects, suggesting a racial difference. Z score values (average value 0, standard deviation 1) increased in the order BB, Bb and bb. This result indicates that allele B is associated with the lower BMD in Japanese, as in European whites. The BMD decrement rate increased in the order bb, Bb and BB, indicating that VDR gene polymorphism may be a regulatory factor for losing BMD. Most of lifestyle variables, calcium intake and vitamin D intake were not correlated with BMD, but the food frequency score (which was defined as values weighted in each of three food categories obtained by factor analysis) was significantly correlated with BMD. Multiple regression analysis showed significant influences of years after menopause, the food frequency score and VDR genotype on BMD. VDR genotype and years after menopause influenced the BMD decrement rate significantly in multiple regression analysis. Neither a relationship between BMD and calcium intake nor between BMD and vitamin D intake by VDR genotype was found. These results suggest that the VDR gene is a genetic factor in BMD and the BMD decrement rate in Japanese.

Adult↗
PubMed1994

Elevated chromosome aberration frequency after X-ray exposure of cultured fibroblasts derived from patients with porokeratosis.

Porokeratosis (PK) is a rare genetic skin disorder inherited as an autosomal dominant trait and regarded as a disease predisposing to cancer. To evaluate chromosomal radiosensitivity of PK cells, we examined chromosome aberration frequency after X-irradiation of cultured skin fibroblasts derived from PK patients and controls. Without X-ray exposure, frequencies of chromosome-type aberrations (exchanges or deletions) were not different between the patients and controls. Following X-ray irradiation, frequencies of deletions in the patient group were significantly increased, whereas those of exchanges were not elevated. No differences in chromatid-type aberration frequency were found between the patients and controls with or without exposure to X-ray. The observed radiosensitivity, though not as high as in ataxia telangiectasia (AT) cells, agrees well with the previously reported higher radiosensitivity of PK fibroblasts in survival analysis.

Analysis of Variance↗
PubMed1994

[Study on the association between risk factors for osteoporosis and bone mineral density].

The relationship between bone mineral density (BMD) and risk factors for osteoporosis was investigated on 146 females (23-68 years old) in Enzan city, Yamanashi prefecture. BMD was measured by DEXA (Dual Energy X-ray Absorptiometry) method. Information regarding menstruation, health status, life-style, quantities of nutrient intake and frequencies of food intake were obtained by questionnaire. Fitness level was determined by exercise test and daily energy expenditure by calorie-counter. The results were as follows; 1) No relationship between physical activities or daily energy consumption and BMD was found. 2) No relationship between calcium intake or vitamin D intake and BMD was found, but a significant and positive correlation coefficient between intake frequency of milk products and BMD was observed. 3) Significant influences of age, BMI, presence of lumbago and food frequency score on BMD were indicated by multiple regression analysis. Food frequency score were defined as values weighted in each of three food category, obtained by factor analysis. 4) Significant influences of height decrement rate per year and number of years postmenopausal on BMD reduction rate per year were indicated by multiple regression analysis. These results suggest that these significant factors are useful in indications of risk for osteoporosis.

Adult↗
PubMed1992

The effect of aging on cell-cycle kinetics and X-ray-induced chromosome aberrations in cultured lymphocytes from patients with Down syndrome.

To evaluate the effects of aging on cytogenetic characteristics of lymphocytes from Down syndrome (DS), cell-cycle kinetics after PHA stimulation and chromosome-type aberration frequencies after X-ray exposure were investigated in vitro in the lymphocytes derived from 4 (or 3 for X-ray treatment) age groups of DS patients and age-matched controls. The results clearly showed higher mitotic and proliferation index levels in younger groups compared to older groups at the various culture intervals, whether the lymphocytes were from the DS patients or controls. The age-related changes of the proliferation index were mainly attributed to a delayed response to PHA as age increased. The changes of PHA responses seemed to be particularly marked during adolescence. Nonetheless, no significant differences were observed between the DS patients and age-matched controls for each age group. In all age groups, frequencies of both chromosome-type exchanges and deletions were elevated in the DS patients by about 1.3 times in comparison with the controls. The magnitude of radiosensitivity, however, seemed to decrease slightly in the 40-49-year group. To our knowledge, the present study is the first report in the literature to deal with the effect of aging on the greater radiosensitivity of DS lymphocytes.

Adolescent↗
PubMed1992

Genetic and environmental factors of bone mineral density indicated in Japanese twins.

To evaluate the effects of genetic and environmental factors on the bone mass, we determined the bone mineral density (BMD) in the total body, the lumbar spine and in the femoral neck in 23 Japanese twin pairs including 21 monozygotic (MZ) pairs, applying dual-energy X-ray absorptiometry. In MZ pairs aged 20-49 years, highly significant intraclass correlation coefficients, ranging from 0.775 to 0.926, were observed at several sites, including the lumbar spine and the femoral neck, which suggests considerable contributions of genetic factors to the BMD. Neither intraclass correlation coefficients nor intrapair differences were found to change with increasing age in the present analysis. In female MZ pairs, exercises both at the present time and in the past were correlated with the BMD at several sites as well as body mass index in multiple regression analyses.

Absorptiometry, Photon↗
PubMed1989

Mitomycin-C-induced sister-chromatid exchanges and cell-cycle kinetics in lymphocytes from patients with Klinefelter syndrome.

The chromosomal sensitivity to mitomycin-C (MMC) and cell-cycle kinetics in cells from patients with Klinefelter syndrome, a sex chromosomal disorder giving a high risk of malignant tumor, were studied by techniques of sister-chromatid exchanges (SCEs). The frequencies of MMC-induced SCEs increased in proportion to the increase in MMC concentration in both patient and normal control cells. At low levels of MMC there were no significant differences in SCE frequencies between the patient and normal control cells, but at MMC concentrations of 3 X 10(-8) M (p less than 0.05) and 1 X 10(-7) M (p less than 0.01), significant increases in the frequency of MMC-induced SCEs were observed in cells from patients compared to cells from normal controls. Although the analysis of cell-cycle kinetics both after various culture times and after treatment with MMC revealed that there were no significant differences between the patient and normal control cells, patients with Klinefelter syndrome showed a tendency to cell-cycle delays after treatment with MMC in comparison with normal controls.

Cell Cycle↗
PubMedDate not supplied

Distribution of apolipoprotein E gene polymorphisms in Japanese patients with Alzheimer's disease and in Japanese centenarians.

We have demonstrated an association between apolipoprotein E (apoE) gene polymorphisms and Alzheimer's disease (AD) in 163 Japanese patients by means of PCR. We found a significant increase in risk of nonfamilial AD for apoE allele epsilon4 in these individuals; this trend decreases with the increase in onset age. In centenarians, the distribution of apoE gene alleles is similar to that in the general population. The protective effect of allele epsilon2 against the development of AD is not statistically significant in our analysis. This indicates that apoE polymorphism is associated with AD regardless of race and that the age of onset is related to the apoE gene in the development of AD.

Aged↗