The effect of renal calcium excretion on bone mineral metabolism of postmenopausal women in Korea / 대한내과학회지

BACKGROUND: Although all postmenopausal women are estrogen deficient, women who have postmenopausal osteoporosis may have some defects, in addition to estrogen deficiency, that explain for their higher rates of bone resorption and greater bone loss, relative to those who do not. To test the hypothesis that one of the defects is an impairment in renal calcium conservation, we have investigated relationship between urinary calcium excretion and bone mineral metabolism of postmenopausal women in Korea. METHODS: We have measured 24-hour urinary calcium level; serum osteocalcin level, serum alkaline phosphatase level; urine deoxypyridinoline level; and bone mineral density in 224 early postmenopausal, 158 late postmenopausal and 145 premenopausal women. RESULTS: 33.0 percent (74/224) of early postmenopausal women in Korea had urinary calcium excretion exceeding 4 mg/kg per day. The early postmenopausal women had higher (p < 0.05) values for mean urinary calcium to creatinine ratio of 0.241+/-0.008 mg/mg of creatinine vs. 0.209+/-0.010 mg/mg of creatinine and higher (p < 0.001) mean serum calcium level of 9.15+/-0.02 mg/dL vs. 8.92+/-0.03 mg/dL than the premenopausal women. Hypercalciuric group of early postmenopausal women had higher (p < 0.05) values for mean urine deoxypyridinoline level (8.6+/-0.4 nMol/mMol Vs. 7.7+/-0.2 nMol/mMol), higher (p < 0.05) mean serum alkaline phosphatase level (73.4+/-2.3 U/L Vs. 67.7+/-1.4 U/L) and lower (p < 0.05) mean bone mineral density of femur neck (0.785+/-0.012 g/cm2 Vs. 0.815+/-0.008 g/cm2) than the normocalciuric group. CONCLUSION: The early postmenopausal women had larger numbers of hypercalciuric women and higher values for urinary calcium excretion than the premenopausal women. Hypercalciuric group of early postmenopausal women had higher values for biochemical markers of bone turnover and lower bone mineral density of femur neck than the normocalciuric group. We suggest that hypercalciuria could be accounted for the partial cause of postmenopausal osteoporosis, but further studies are needed to elucidate the direct effect about that.

Expression of Estrogen Receptor and Telomerase Activity in Chorionic Villi and Decidua of Early Human Gestation / 대한산부인과학회잡지

OBJECTIVE: To investigate whether there is any differences between normal pregnancy (NP) and spontaneous abortion (SAB) regarding estrogen receptor (ER) expression and telomerase activity (TA) in the chorionic villi and decidual tissues. METHODS: Chorionic villi and decidual tissues were obtained between 6 and 9 weeks' gestation from 14 patients with SAB and 17 normal pregnant women who have undergone an elective abortion. All tissue samples were assayed for ER with enzyme immunoassay and also TA was analysed using telomeric repeat amplication protocol. RESULTS: A significant decrease in ER expression (2.81+/-2.77 fmol/mg of protein; p<.001) was demonstrated in SAB group compared to that of NP group (4.56+/-1.85 fmol/mg) in decidua. However, no significant difference in ER expression in chorionic villi was found between the two groups. SAB group showed significantly lower levels of TA than that of NP group in both chorionic villi (21.4% vs. 82.4%; p=.002) and deciduas (7.1% vs. 52.9%; p=.009). CONCLUSION: Our results suggest that decreased level of ER expression in deciduas might cause decidual senescence and eventually, spontaneous abortion.

Effect of Hypoxia on Telomerase Activity in Placental Tissue in Pregnancies with Fetal Growth Restriction / 대한산부인과학회잡지

OBJECTIVE: To observe the difference in telomerase activity (TA) expression in the placenta between fetal growth restriction (FGR) with preeclampsia and those without and to evaluate the effect of oxygen concentration on the TA expression in the trophoblastic cells. METHODS: Telomerase activity was measured in 48 (normal pregnancies, 16; preeclampsia with FGR, 15; normotensive FGR, 17) placentas which were obtained between 32 and 41 weeks' gestations. Trophoblastic cells were extracted from 8 chorionic villi samples obtained from 8-10 weeks' placenta and were cultured in either 2%, 8%, and 20% oxygen atmosphere. Then TA was examined by using telomeric repeat amplification protocol (TRAP) assay. RESULTS: During 3rd trimester of pregnancy, exhibited TA expression in normal pregnancy, FGR complicated by preeclampsia, and normotensive FGR groups were 11 of 16 (68.8%), 4 of 15 (26.7%), and 4 of 17 (23.5%), respectively. Significantly lower level of TA was detected in the FGR group compared to the normal pregnancies (p=0.009), whereas within FGR pregnancies, presence of preeclampsia did not seem to have statistically significant effect on TA expression. TA expression levels were measured by optical density in trophoblasts cultured under various oxygen concentration which revealed that significantly higher TA was exhibited in the cells cultured in 2% oxygen compared to 8% and 20% (p<0.001). However no significant difference was noted in TA between cells cultured in 8% and 20% oxygen. CONCLUSION: Decreased TA in the placenta from pregnancies with FGR was noted regardless of presence of preeclampsia indicating a probable correlation between FGR and placental senescence. Since increased TA was noted in trophoblastic cells that were cultured in hypoxic condition, we could speculate that the intervillous oxygen tension during early-stage placental development plays a certain role in the placental degeneration in pregnancies complicated by FGR and preeclampsia.