Effect of N, N-Dimethylglycine on Homocysteine Metabolism in Rats Fed Folate-Sufficient and Folate-Deficient Diets.

OBJECTIVE: This study aimed to investigate the effects of N,N-dimethylglycine (DMG) on the concentration and metabolism of plasma homocysteine (pHcy) in folate-sufficient and folate-deficient rats. METHODS: In this study, 0.1% DMG was supplemented in 20% casein diets that were either folate-sufficient (20C) or folate-deficient (20CFD). Blood and liver of rats were subjected to assays of Hcy and its metabolites. Hcy and its related metabolite concentrations were determined using a liquid chromatographic system. RESULTS: Folate deprivation significantly increased pHcy concentration in rats fed 20C diet (from 14.19 ± 0.39 µmol/L to 28.49 ± 0.50 µmol/L; P < 0.05). When supplemented with DMG, pHcy concentration was significantly decreased (12.23 ± 0.18 µmol/L) in rats fed 20C diet but significantly increased (31.56 ± 0.59 µmol/L) in rats fed 20CFD. The hepatic methionine synthase activity in the 20CFD group was significantly lower than that in the 20C group; enzyme activity was unaffected by DMG supplementation regardless of folate sufficiency. The activity of hepatic cystathionine ß-synthase (CBS) in the 20CFD group was decreased but not in the 20C group; DMG supplementation enhanced hepatic CBS activity in both groups, in which the effect was significant in the 20C group but not in the other group. CONCLUSION: DMG supplementation exhibited hypohomocysteinemic effects under folate-sufficient conditions. By contrast, the combination of folate deficiency and DMG supplementation has deleterious effect on pHcy concentration.

Breast milk selenocystine as a biomarker for selenium intake in lactating women at differential geographical deficiency risk in China.

BACKGROUND AND OBJECTIVES: A reliable biomarker for optimal selenium (Se) intake in lactating women is not currently available. METHODS AND STUDY DESIGN: Daily dietary Se intake in lactating women was calculated from a 24-hour meal record survey for over 3 days. Se levels in plasma and breast milk were measured through inductively coupled plasma mass spectrometry. Plasma selenoprotein P 1 levels and glutathione peroxidase 3 activity were measured using an enzyme-linked immunosorbent assay. Ultra-performance liquid chromatography-tandem mass spectrometry was used to analyze proteinaceous Se species in enzymatically digested breast milk. RESULTS: Dietary Se intakes of lactating women from Liangshan, Beijing, and Enshi were 41.6±21.2 ng/d, 51.1±22.6 ng/d, and 615±178 ng/d, respectively (p<0.05). The Se levels in the blood and breast milk were significantly associated with the dietary Se intake (p<0.05). The proteinaceous Se species in breast milk were SeMet and SeCys2. The levels of SeMet in the lactating women from Liangshan, Beijing, and Enshi were 3.31±2.44 ng Se/mL, 7.34±3.70 ng Se/mL, and 8.99±9.64 ng Se/mL, while that of SeCys2 were 13.7±12.0 ng Se/mL, 35.6±20.9 ng Se/mL, and 57.4±13.2 ng Se/mL, respectively. Notably, the concentration of SeCys2, the metabolite of unstable SeCys, reached a saturation platform, whereas no similar phenomenon were found for the total Se SeMet from Secontaining proteins. CONCLUSIONS: SeCys2 in breast milk is a potential biomarker for determining the optimal Se intake in lactating women.

The Synergistic Effect of Serine with Selenocompounds on the Expression of SelP and GPx in HepG2 Cells.

We explored the synergistic effect of serine combined with several selenocompounds or used alone on the expression of selenoprotein P (SelP) and glutathione peroxidase (GPx) in this study. We first compared the SelP and GPx expression difference between HepG2 and Hela cells treated with serine and finally chose HepG2 as experimental cell. In the serine-used-alone experiment, three kinds of selenium nutritional models (low-, adequate-, and high-selenium) were established and serine was 10 times gradient diluted (0.01 to 100 µmol/L). In the combined experiment, the selenocompound doses were set as 0.01, 0.1, and 1 µmol Se/L and serine was set according to its molar ratio with the selenocompounds. We found that SelP and GPx concentrations in the low-, adequate-, and high-selenium models increased following with serine dose. When the concentration of sodium selenite and SeMet was 1 µmol Se/L while MeSeCys was 0.1 and 1 µmol Se/L, SelP concentrations for serine combined with selenocompounds groups were significantly higher than that of selenocompounds used alone. When the concentration of sodium selenite was 0.1 µmol Se/L, SeMet was 0.1 and 1 µmol Se/L while MeSeCys was 0.01 and 1 µmol Se/L, GPx concentrations for serine combined with selenocompounds groups were significantly higher than that of selenocompounds used alone. Our preliminary result indicated the beneficial effect of serine on the expression of SelP and GPx, which suggested that it might be a candidate for combined selenium supplement.

Suppression effects of betaine-enriched spinach on hyperhomocysteinemia induced by guanidinoacetic acid and choline deficiency in rats.

Betaine is an important natural component of rich food sources, especially spinach. Rats were fed diets with betaine or spinach powder at the same level of betaine for 10 days to investigate the dose-dependent effects of spinach powder supplementation on hyperhomocysteinemia induced by guanidinoacetic acid (GAA) addition and choline deprivation. The GAA-induced hyperhomocysteinemia in rats fed 25% casein diet (25 C) was significantly suppressed by supplementation with betaine or spinach, and it was completely suppressed by taking 11.0% spinach supplementation. The choline deprivation-induced enhancement of plasma homocysteine concentration in rats fed 25% soybean protein diet (25S) was markedly suppressed by 3.82% spinach. Supplementation with betaine or spinach partially prevented the effects of GAA on hepatic concentrations of methionine metabolites. The decrease in activity of betaine-homocysteine S-methyltransferase (BHMT) and cystathionine ß-synthase (CBS) in GAA-induced hyperhomocysteinemia was recovered by supplementation with betaine or spinach. Supplementation with betaine or spinach did not affect BHMT activity, whereas it partially restored CBS activity in choline-deprived 25S. The results indicated that betaine or spinach could completely suppress the hyperhomocysteinemia induced by choline deficiency resulting from stimulating the homocysteine removal by both remethylation and cystathionine formation.

[Relationship between estrogen receptor gene Px haplotype and the effect of calcium and soy isoflavone supplementation on bone mineral density of Chinese postmenopausal women].

OBJECTIVE: To investigate the relationship between estrogen receptor gene Px haplotype and the effect of calcium and soy isoflavone supplementation on bone mineral density (BMD) of Chinese postmenopausal women. METHODS: It was a randomly controlling test for 12 months. The Pvu II and Xba I polymorphisms of ER-alpha gene were detected by using restriction fragment length polymorphisms (RFLP) in 691 Chinese postmenopausal women, aged 45-65 years. In 497 carriers of definitive Pvu II-Xba I haplotype, 93 subjects were chosen randomly. BMD was measured by dual energy X-ray absorptiometry (DXEA). According to BMD T score in any skeleton site of 81 subjects at baseline, 29 subjects with T > or = -1.5 were grouped into observation group, and 52 subjects with T < -1.5 were randomly assigned into two intervention groups and received either a 100 mg soy isoflavone and 440 mg Ca and 100 IU VD supplement/d (n = 26) or 440 mg Ca and 100 IU VD supplement/d (n = 26). BMD of the whole body, lumber (L2-L4), and hip were measured at baseline and after 12 months. RESULTS: After one year fellow-up, the BMD at L2-L4, femur neck site and whole body were significantly decreased as compared with those of baseline (P < 0.05, change percent of BMD as follows: -3.31%, -3.09%, -1.88%) in observation group, and the whole body BMD was significantly lower at 12 month than that at baseline in subjects with Px haplotype (percent change was -2.44%, P < 0.05), but no difference was found in subjects without Px haplotype. Whole body and femur neck BMD were significantly decreased in both Ca group and Ca + soy isoflavone group, but no significant difference of change percent between two groups. There were no significant changes in L2-L4 and trochanter BMD irrespective of treatment. ER-alpha Px haplotype had no effect on the changes in BMD in both Ca group and Ca + soy isoflavone group. CONCLUSION: The rate of bone loss in Chinese postmenopausal women seems to haverelation to ER Px haplotype. Calcium supplementation for 1 year might lower the bone loss rate, but soy isoflavone supplementation for 1 year had notshowu no effects. The effect of supplementation had no relationship with ER Px haplotype.

[Study on the association between estrogen receptor-alpha gene polymorphisms and pubertal skeletal developmental status in China].

OBJECTIVE: To investigate the association between estrogen receptor-alpha (ER-alpha) gene polymorphisms, pubertal bone mineral density (BMD) and bone turnover markers, to better understand the frequencies of ER-a genotypes. METHODS: The ER-alpha Pvu II and Xba I genotypes were determined by PCR-RFLP in 158 healthy adolescent girls (12-14 years old) while BMD was measured by dual-energy X-ray absorptiometry (DEXA). The bone turnover markers (BAP, BGP, TRACP) and calcium adjust hormone (25-OH-VitD, E2) were detected by ELISA. The relationship among BMD, bone turnover markers, and polymorphisms of ER-a were examined. RESULTS: (1) Although the bone turnover markers had a trend in ER-alpha Pvu II genotypes as pp>PP>Pp but no significant difference was found (P > 0.05). There were no significant differences found among Xba I genotypes and between Px haplotype and non-Px haplotype. (2) No association was noticed between ER-a genotype and BMD at any site of the forearm and the whole body. Compared with non-Px haplotype, the Px haplotype had lower BMD, but there was no significant difference noticed (P > 0.05). CONCLUSION: ER-alpha gene Pvu II and Xba I polymorphism seemed not potentially influence on BMD and bone turnover markers in the pubertal girls in Beijing, suggesting that it might not be the major genetic factor regarding this population.

[Association of bone mineral density with gene polymorphisms and environmental factors in Chinese postmenopausal women].

OBJECTIVE: To investigate the relationship between bone mineral density (BMD) and polymorphisms of the eatrogen receptor (ER) and vitamin D receptor (VDR) in relation to some environmental factors. METHODS: Ninety postmenopausal Chinese rural women of Han population, aged 45 to 65, were voluntarily enrolled in this study. We conducted BMD measurement of the lumber spine and hip by dual energy X-ray absorptiometry (DXEA) and performed a questionnaire survey of diet intake and outside activity. The polymorphisms of ER gene and VDR gene were determined using polymerase chain reaction restriction fragment length polymorphism ( PCR-RFLP). RESULTS: There is no significant influence of ER Px haplotype on BMD in Chinese women. VDR Bsm I polymorphisms was associated with BMD at the lumbar spine and the BMD in the Bb genotype was lower than in the bb genotype (P < 0.05), but the significant difference was weakened after adjusting for confounding factors such as age height weight activity diet and menopause age. Women with the ER Px haplotype and VDR B allele genotype had lowest BMD at lumber (P < 0.05), but the difference of BMD became not significant after adjusting for confounding factors such as age height weight activity diet and menopause age. Diet calcium, protein, carbohydrate and energy simply related to BMD. Stepwise multiple regression analysis showed that age and body weight were strong predictor of BMD in postmenopausal women. Other significant predictors were menopausal age and carbohydrate at lumber spine and menopausal age at femur neck. CONCLUSION: BMD was not associated with ER genotype but with VDR Bsm I polymorphism. Environmental factors influence the relationship between gene polymorphism and BMD.

[Fractional utilization of reduced iron powder in Chinese child bearing age women with dual stable isotopes].

OBJECTIVE: To study the utilization of reduced iron powder in child-bearing-age women with traditional Chinese food. METHODS: 20 health child-bearing-age women were randomly divided into two groups. With ferrous sulfate as control, the utilization of reduced iron was measured using dual stable isotopes. RESULTS: The fractional utilization of iron in ferrous sulfate was 5.8%, while in reduced iron powder was 2.1%. The rates of absorbed iron incorporated into hemoglobin were 70.1% and 91.3% respectively. The differences were statistic significant. CONCLUSION: With traditional Chinese food, the utilization of reduced iron in child-bearing-age women was 2.1%, and the rate of absorbed iron incorporated into red blood cells was 91.3%.