Effect of Different Calcium Supplements on Bone Metabolism in Rats

Osteoporosis, characterized by loss of bone mass and microarchitectural deterioration of bone tissue, results in enhanced bone fragility and increases risk of fractureIll. In China, the incidence of primary osteoporosis is as high as 50%-70% in 60-69 years old females and approximately 30% in 60-69 years old males[21, which is closely related with the low intake of calcium. According to the nationwide nutrition and health survey in 2002 in China, the average daily calcium intake of Chinese residents is 391 mg, accounting for 41% of the recommended calcium intake.

Change of BMD after Weaning or Resumption of Menstruation in Chinese Women with Different FokI VDR-genotypes:A Randomized,Placebo-controlled,Calcium Supplementation Trial

Objective To investigate the effect of calcium supplementation on bone mineral density （BMD） in Chinese women with different Fokl vitamin D receptor （VDR） genotypes （FF, Ff, and ff） after weaning or resumption of menstruation during lactation. Methods A total of 40 subjects with the same Fokl VDR genotype were randomly divided into two groups： one received calcium tablet （600 mg once daily as CaCO3） and the other placebo tablet once daily for 1 year. At baseline, BMD was measured by dual-energy X-ray absorptiometry at lumbar spine （L2-L4） and at left hip whereas serum PICP, serum OC, and urinary CTX, serum 25（OH）VitD3, and serum estradiol were measured at weaning and I year thereafter. Results After the intervention, BMD at lumbar spine and at left hip increased significantly in all these women with a trend among different Fokl VDR genotypes such as FF 〉 Ff 〉 ff （P〈O.05, 〈0.01, and 〈0.001, respectively）. BMD at lumbar spine in women with FF VDR genotype increased much more rapidly than in those with ff VDR genotype （P〈0.05）. Compared with the control group women with the FF genotype regained more BMD after calcium supplementation （P〈0.05）. Conclusion Daily calcium 600 mg supplementation has beneficial effect on the bone health of women with FF VDR genotype.

Association of Estrogen Receptor-α Gene PvuII Polymorphisms with the Effect of Calcium Supplementation on Skeletal Development in Chinese Pubertal Girls

Objective To investigate the association of estrogen receptor alpha （ER-c0 PvulI polymorphisms with the effect of calcium supplementation on bone development in Chinese pubertal girls, and to study the importance of calcium supplementation by maximizing the peak bone mass at their pubertal stage for bone development and osteoporosis prevention and the role of estrogen in regulating bone mass. Methods Ninety-four pubertal girls were recruited in the study and divided into two groups and three sub-groups according to the ER-α PvulI polymorphisms. One year before and after calcium supplementation, bone mineral density （BMD） was measured by DEXA, while BGP, BAP, TRACP5b, and 25-OH-VitD3, as well as estrogen were detected by ELISA. Analysis of covariance was used to examine the effect of ER-ct polymorphisms on bone development. Results The absolute increase and percentage change of BGP were significantly higher in the supplemented group than in the control group （P〈0.05）. In the intervened group, The increase and percentage change of the total body and radio distal 1/3 BMD were higher in PP than in PP genotype （P〈0.05）, and the increase of BAP in Pp was also higher than PP in the same group （P〈0.05）. Conclusion PP genotype shows a better response to calcium supplementation than the other Pvull polymorphisms.

Effect of calcium supplementation on severe hypocalcemia in patients with secondary hyperparathyroidism after total parathyroidectomy

BACKGROUND Severe hypocalcemia(SH)is a dreaded complication of total parathyroidectomy(TPTX)without auto-transplantation.AIM To compare conventional and preventive calcium supplementation(CS)regimens in terms of SH occurrence after TPTX.METHODS This retrospective study included patients who underwent TPTX between January 2015 and May 2018 at the China-Japan Friendship Hospital.From January 2015 to May 2016,conventional CS was performed in patients who underwent TPTX,with calcium amounts adjusted according to postoperative serum calcium levels.From October 2016 to May 2018,preventive CS was performed according to preoperative alkaline phosphatase(ALP)levels.The patients were defined as lowrisk(ALP<500 U/L)and high-risk(ALP>500 U/L)for SH.All preoperative blood samples were collected in the fasting state on the day before surgery.Postoperative blood samples were obtained at 6-7 AM from the first postoperative day.RESULTS A total of 271 patients were included.These patients were 47.7±11.1 years old,and 57.6%were male.Their mean body mass index(BMI)was 22.9±3.8 kg/m^(2).There were no significant differences in sex,age,BMI,preoperative ALP,serum calcium,serum phosphorus,calcium-phosphorus ratio,and intact parathyroid hormone(iPTH)between the two CS groups.Compared with conventional CS,preventive CS led to lower occurrence rates of hypocalcemia within 48 h(46.0%vs 74.5%,P<0.001)and SH(31.7%vs 64.1%,P<0.001).Multivariable analysis showed that preoperative iPTH levelsodds ratio(OR)=1.001,95%confidence interval(CI:1.000-1.001,P=0.009),preoperative ALP amounts(OR=1.002,95%CI:1.001-1.003,P=0.002),preoperative serum phosphorus levels(OR=8.729,95%CI:1.518-50.216,P=0.015)and preventive CS(OR=0.132,95%CI:0.067-0.261,P<0.001)were independently associated with SH.In patients with preoperative ALP≥500 U/L,only preventive CS(OR=0.147,95%CI:0.038-0.562.P=0.005)was independently associated with SH.CONCLUSION This study suggests that preventive CS could reduce the occurrence of SH,indicating its critical value for hypocalcemia after TPTX.

Unlocking the potential of amorphous calcium carbonate: A star ascending in the realm of biomedical application

Calcium-based biomaterials have been intensively studied in the field of drug delivery owing to their excellent biocompatibility and biodegradability.Calcium-based materials can also deliver contrast agents,which can enhance real-time imaging and exert a Ca^(2+)-interfering therapeutic effect.Based on these characteristics,amorphous calcium carbonate(ACC),as a brunch of calcium-based biomaterials,has the potential to become a widely used biomaterial.Highly functional ACC can be either discovered in natural organisms or obtained by chemical synthesis However,the standalone presence of ACC is unstable in vivo.Additives are required to be used as stabilizers or core-shell structures formed by permeable layers or lipids with modified molecules constructed to maintain the stability of ACC until the ACC carrier reaches its destination.ACC has high chemical instability and can produce biocompatible products when exposed to an acidic condition in vivo,such as Ca^(2+) with an immune-regulating ability and CO_(2) with an imaging-enhancing ability.Owing to these characteristics,ACC has been studied for selfsacrificing templates of carrier construction,targeted delivery of oncology drugs,immunomodulation,tumor imaging,tissue engineering,and calcium supplementation.Emphasis in this paper has been placed on the origin,structural features,and multiple applications of ACC.Meanwhile,ACC faces many challenges in clinical translation,and long-term basic research is required to overcome these challenges.We hope that this study will contribute to future innovative research on ACC.

Calcium deficiency： where does the diagnostic criterion come from and by what is bone health influenced？

Dietary surveys suggest that a considerable proportion of the population fail to consume recommended amounts of calcium m both developing and developed countries. Recommended allowance for dietary calcium has attracted many controversies and there are discrepant opinions on how to meet the recommendations in the global scientific community.

CALCIUM SUPPLEMENTATION DURING PREGNANCY FOR REDUCING PREGNANCY INDUCED HYPERTENSION

Pregnancy induced hypertension (PIH) is a common complication in pregnancy and prenatal stage. Because the direct and indirect relationship between low calcium intake and many diseases, such as rachitis, young age myopia and hypertension, calcium supplementation has been a hot topic among nutritionists, Randomized trials of calcium supplementation during pregnancy were conducted in 212 healthy primipara. They were divided into 4 groups and pave 120mg, 240mg, Ig or 2g of calcium daily from 20 to 28wks of gestation up to delivery respectively. As a result, the incidence of PIH was 8.9%, 7.5%, 8% and 4% respectively in these groups, The control group (106 pregnant women) who did not receive calcium gave an incidence of 18%. Supplementation of 2g of calcium daily showed significant resutls in lowering the incidence of PM (P<0.05) without any adverse effects. In 1992 calcium supplementation was widely used in antenatal clinic. 200 cases with intake of 2g calcium were compared with corresponding non-calcium supplementation cases, and the incidence of PIH was 7.5% and 16.5% (P< 0.005) respectively. Mediating parathyroid hormone and renin activity are thought to be the effect of calcium on decreasing the incidence of PIH,