When the usage of hydroxyapatite (HAp) was first approved at clinics by the Kouseishou (Japanese FDA) as a bone substitute (APACERAM), the upper limit of pore content was set at 60%. Cells play an important role in bone repair, especially in regeneration therapy, but on using these HAps, the cells cannot penetrate deeply into them because their inside pores rarely connect. To promote cell penetration into the inside of the HAps, we have developed superporous HAps (HAp-Ss). First, phosphoric acid was added to a calcium hydroxide solution, and the mixture was dried by the spray-dry method to produce fine primary particles. Then, two kinds of surfactants were used to form a large amount of pores. These two HAp-Ss have 85% porosity and interconnected pores in the inside. They were tested with a culture of primary rat osteoblasts, which showed good penetration therein. The penetrated osteoblasts maintained high alkaline phosphatase activity during the culture period. This indicates that the developed HAp-Ss are very good bone substitutes and also useful scaffolds in bone regeneration therapy.

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Prenatal under-nutrition involves changes in the epigenetic regulation of specific genes. Maternal magnesium (Mg) deficiency affects maternal glucocorticoid metabolism, but the mechanisms underlying changes in glucocorticoid homeostasis of offspring are not well understood. In this study, we investigated the effects of feeding pregnant rats a Mg-deficient diet (0.003% magnesium) on the methylation of cytosine-guanine (CpG) dinucleotides in hepatic glucocorticoid genes of neonatal offspring, compared with controls (0.082% magnesium). Methylation of CpG dinucleotides in the peroxisome proliferator-activated receptor α (Ppara), glucocorticoid receptor (Nr3c1) and 11β-hydroxysteroid dehydrogenase-2 (Hsd11b2) promoters in the liver were measured by pyrosequencing. Quantitative real-time PCR was used to assess hepatic mRNA expression of each gene. Mean methylation of the Hsd11b2 promoter in the Mg-deficient offspring (33.2%) was higher than in controls (10.4%). This was due to a specific increase at CpG dinucleotides 1 (20.0% vs. control 10.1%), 2 (58.8% vs. 17.0%), 3 (29.7% vs. 6.2%) and 4 (38.7% vs. 8.8%) (p < 0.05). Ppara and Nr3c1 methylation status and expression did not differ between the groups. No significant difference was noted between male and female pups, which were equally represented. Therefore, a Mg-deficient diet alters glucocorticoid metabolism, predicting higher hepatic intracellular glucocorticoid concentrations, and is possibly a key mechanism that induces the metabolic complications of Mg deficiency.

Cultured growth cartilage cells of young rabbits were stimulated by three levels (10, 1, and 0.1 microA) of constant direct current (DC). The effect of DC was examined by measuring the activities of proteoglycan synthesis (uptake of [35S]sodium sulfate and toluidine blue staining) and DNA synthesis (uptake of [3H]thymidine). DC increased syntheses of both proteoglycans and DNA when 1 microA (calculated current density of 1 microA/cm2) was applied for 3 days. A longer stimulation resulted in a larger difference between stimulated and unstimulated cells. Ten-microampere stimulation devitalized the cells, while 0.1 microA had no effect on cell activities.

Background: Many epidemiologic studies have reported a link between calcium (Ca) deficiency and metabolic syndrome. In this study, we examine Ca deficiency in rats and whether changes in glucocorticoid metabolism are induced. Methods: Twelve-week-old female Wistar rats were weaned onto a very-low-Ca diet (low-Ca group) or a control diet (control group) for 2 weeks. Quantitative real-time PCR was used to assess mRNA for 11β-hydroxysteroid dehydrogenase-1 (11β-HSD1), 11β-HSD2, phosphoenolpyruvate carboxykinase, peroxisome proliferator-activated receptor-α, and glucocorticoid receptor in the liver. Concentrations of adiponectin, leptin, corticosterone, intact parathyroid hormone, asymmetrical dimethylarginine and insulin in fasting serum were determined using a rat-specific enzyme-linked immunosorbent assay. Glucose concentrations were measured using a glucose oxidase system. Serum ionized Ca levels were measured with an automatic ion-selective electrode analyzer. Serum nitrite/nitrate levels were measured using a colorimetric assay kit. Results: After 2 weeks, no differences in serum glucose, corticosterone or insulin levels were observed. The low-Ca group rats showed higher homeostasis model assessment insulin resistance, lower adiponectin and higher intact parathyroid hormone levels. Serum nitrite/nitrate and asymmetrical dimethylarginine were significantly higher in the low-Ca group than in the control group. The expression of hepatic 11β-HSD1 mRNA was upregulated, while hepatic phosphoenolpyruvate carboxykinase expression was downregulated in the low-Ca group. Glucocorticoid receptor, peroxisome proliferator-activated receptor-α and 11β-HSD2 expression levels showed a similar tendency. Conclusion: A low-Ca diet alters glucocorticoid metabolism, which leads to hepatic upregulation of 11β-HSD1, and is possibly a key mechanism inducing the metabolic complications of Ca deficiency.