PubMed Health⌕ Search

Biomedical subjects

Osamu Chaki

Publications and source records attributed to Osamu Chaki.

9 recordsLinked to original sources
PubMed2007

[Therapeutic agents for disorders of bone and calcium metabolism: Bazedoxifene].

Selective estrogen receptor modulators (SERMs) have the potential to provide the skeletal benefits of estrogen without the increased risk of uterine and breast cancer. Raloxifene, second generation SERM has been approved for the prevention and treatment of osteoporosis. Bazedoxifene (BZA, TSE-424Z), novel SERM, acts as a tissue selective estrogen antagonist or agonist. Bazedoxifene inhibited bone turnover and prevented bone loss caused estrogen deficiency. Furthermore, this SERM did not affect the uterine endometrial thickness and reduced serum cholesterol. These date suggest that Bazedoxifene is novel potential drug for the prevention of osteoporosis in postmenopausal women.

Animals↗
PubMed2006

CYP17 and COMT gene polymorphisms can influence bone directly, or indirectly through their effects on endogenous sex steroids, in postmenopausal Japanese women.

We aimed to assess whether circulating sex steroids would influence bone density and bone loss, whether part of this influence could be explained by genetic variation measured as polymorphisms in candidate genes affecting circulating hormone levels, or whether gene polymorphisms would have direct effects on bone in 229 postmenopausal Japanese women aged 46 years and over who had been followed for eight years (Yokohama Cohort). Bone mineral density (BMD) in the lumbar spine (L), femoral neck (FN), total hip (T) and distal radius (R) was measured every year, and endogenous sex steroid levels were determined at the start of the study. We investigated the polymorphisms of estrogen-metabolizing enzyme gene, CYP17; estrogen biosynthesis (high activity, A2/A2), CYP1A1; hydroxylation (high inducibility, vt/vt) and COMT; inactivation (low activity, L/L) with PCR-based restriction fragment length polymorphism assays. Dehydroepiandrosterone (DHEA) and androstenedione (AND) levels significantly correlated with bone density in both the axial (L) and the appendicular skeleton (FN, T and R) (r=0.194-0.229; P<0.05) whereas estradiol (E2) and AND showed significant correlations with bone change only at the axial skeleton (r=0.205 and r=-0.139, respectively; P<0.05) on the total cohort. These correlations remained significant in thin/normal-weight women [body mass index (BMI) <25 kg/m2)] even after adjustment for years since menopause (YSM) and BMI or age and BMI, suggesting an interaction of BMI and sex steroid/BMD association. On the total cohort, a difference in endogenous DHEA levels between CYP17 homozygote A2 and non-homozygote A2; an increasing trend in AND levels from COMT L/L, L/H, to H/H; and a difference in TS level between COMT homozygote L and non-homozygote L were separately observed. All observations were significant for unadjusted and adjusted analysis, except for COMT and TS. In thin/normal-weight women (BMI <25 kg/m2), the same effects of CYP17 genotypes on DHEA were observed as on the total cohort. CYP17 and COMT genes showed some direct influence on bone density. Mean percent change in T-BMD was negative for CYP17 non-homozygote A2 in contrast to a positive value for homozygote A2. Mean percent change in R-BMD showed the difference between COMT homozygote L and non-homozygote L with a larger decrease for the homozygote L. Together, CYP17 and COMT genotypes might have some effect on bone both directly and indirectly through their effects on endogenous sex steroids in postmenopausal Japanese women.

Aged↗
PubMed2006

[Next generation selective estrogen receptor modulators].

Selective estrogen receptor modulators (SERMs) have the potential to provide the skeletal benefits of estrogen without the increased risk of uterine and breast cancer. Raloxifene, second generation SERM has been approved for the prevention and treatment of osteoporosis. Lasofoxifene (LAS) and bazedoxifene (BZA, TSE-424), novel SERMs, act as a tissue selective estrogen antagonist or agonist. These novel SERMs inhibited bone turnover and prevented bone loss caused estrogen deficiency. Furthermore, these SERMs did not affect the uterine endometrial thickness and reduced serum cholesterol. These date suggest that LAS and TSE-424 are novel potential therapy for the prevention of osteoporosis in postmenopausal women.

Animals↗
PubMed2006

[Osteoporosis].

Explore the source record for details and available documents.

Animals↗
PubMed2005

[Fracture risk and biochemical markers of bone turnover].

BMD is prescribed by the balance of bone resorption and osteogenesis. In osteoporosis, this balance collapses according to a certain cause, bone loss starts as a result because bone resorption exceeds osteogenesis. Since a bone turnover marker shows the bone metabolism at the time of measurement quantitatively, it is thought that the change in BMD is reflected. Therefore, it is in predicting bone reduction of the future and fast bone loser identifying is expected by measuring bone turnover markers. Reduction of bone density is large in high turnover of bone metabolism, and it is shown clearly by recent research that the risk of fracture goes up. There is the necessity for evaluation of the bone turnover markers which made fracture the end point also in Japan.

Biomarkers↗
PubMed2003

Estrogen-metabolizing gene polymorphisms, but not estrogen receptor-alpha gene polymorphisms, are associated with the onset of menarche in healthy postmenopausal Japanese women.

Both onset and cessation of menstruation have strong genetic inclination. We aimed to identify genetic factors influencing the onset of menarche and natural menopause in a Japanese population by investigating the polymorphisms of estrogen receptor-alpha and estrogen-metabolizing enzyme genes. Three hundred seventeen postmenopausal Japanese women, aged 46 yr and over, were enrolled in this study under informed consent. Genomic DNA was extracted from peripheral leukocytes, and PCR-based restriction fragment length polymorphism assays were used to determine estrogen receptor-alpha: PvuII, XbaI, and estrogen-metabolizing enzymes; CYP17, estrogen biosynthesis (high activity, A2/A2, CYP1A1), hydroxylation (high inducibility, vt/vt, and COMT), inactivation (low activity, L/L) genotypes. There were no significant differences in ages at menarche and natural menopause or years of menstruation among each PvuII or XbaI genotype and seven combinations of PvuII and XbaI genotypes. We found that ages at menarche in women with A1/A2 (higher activity of CYP17; 13.6 +/- 1.2 yr) were significantly earlier than in those with A1/A1 (lower activity of CYP17; 14.1 +/- 1.3 yr). There were no significant differences in age at natural menopause and years of menstruation among each CYP17, CYP1A1, or COMT genotype. The small sample size of each combination of estrogen-metabolizing genotypes made it impractical to evaluate the effects of the interdependency of each genotype, including extreme genotype categories such as A2/A2L/Lvt/vt vs. A1/A1H/Hwt/wt genotypes, on ages at menarche and/or natural menopause. The results suggest that the estrogen-metabolizing CYP17 genotype influences age at menarche in healthy postmenopausal Japanese women.

Aged↗