Clinical Benefit of the Change of Dialysate Calcium Concentration From 3.0 to 2.75 mEq/L

Because active vitamin D preparations and calcimimetics have been widely used to treat secondary hyperparathyroidism, maintenance of acceptable serum calcium and phosphate levels is important. A 2.75 mEq/L dialysate calcium product, which may bring the calcium balance closer to 0, has recently been launched, and we had an opportunity to examine its possible benefits. We performed a 6‐month retrospective review after switching from 3.0 mEq/L to 2.75 mEq/L calcium dialysate in 85 outpatients undergoing chronic hemodialysis. We evaluated blood biochemical parameters, including predialysis and postdialysis serum calcium and phosphate levels, predialysis intact parathyroid hormone (iPTH) levels; dialysis dose (Kt/V); and doses of concomitant active vitamin D preparations, calcimimetics, phosphate binder, and erythropoiesis‐stimulating agents. Postdialysis calcium levels were significantly lower and predialysis corrected calcium levels significantly decreased. The change in calcium levels before and after dialysis was smaller after switching of the dialysate than before. iPTH levels significantly increased 1 month after switching of the dialysate. No remarkable changes were observed in phosphate levels or Kt/V. The dose of alfacalcidol, one of the concomitant drugs, somewhat increased, and no remarkable changes in dosage were observed for other concomitant drugs. These results were favorable in terms of calcium balance. However, there may be limitations in interpreting the results, but the resultant calcium levels suggest that switching to 2.75 mEq/L calcium dialysate may improve the control of calcium levels. In addition, it is hoped that the treatment choice of secondary hyperparathyroidism is extended.     

Patterns of tooth agenesis in Japanese subjects with bilateral agenesis of mandibular second premolars

The aim of this study was to explore the patterns of tooth agenesis in Japanese orthodontic patients with bilateral agenesis of mandibular second premolars. A total of 80 Japanese orthodontic patients with 2 congenitally missing mandibular second premolars were selected as the subjects of this study (experimental group). Another 80 individuals without bilateral agenesis of mandibular second premolars were collected for comparison (control group). The 2 groups were matched with regard to sex. Radiographs, dental casts and records of medical and/or dental treatment were used to identify tooth agenesis. The Chi-square test, odds ratio, and test for equality were used to make statistical comparisons. The prevalence rates of other types of tooth agenesis were significantly higher in the experimental group than in the control group. The occurrence of agenesis of maxillary and mandibular lateral incisors and third molars, and maxillary second premolars was also significantly higher in the experimental group than in the control group. Significantly increased prevalence rates of symmetrical tooth agenesis, with third molars included, and oligodontia were observed in the experimental group. Japanese subjects with bilateral agenesis of mandibular second premolars are at significantly high risk of agenesis of other types of permanent teeth, symmetrical tooth agenesis and oligodontia.     

Photo-induced in situ crosslinking of polymer brushes with dimethyl maleimide moieties for dynamically stimulating stem cell differentiation

We designed photo-crosslinkable polymer brushes with dimethylmaleimide moieties, in order to demonstrate dynamic stimulation of cell differentiation in mesenchymal stem cells (MSCs). The polymer brushes were synthesized by surface-initiated reversible addition fragmentation chain transfer polymerization using dimethylmaleimide ethyl methacrylate and methyl methacrylate on a chain transfer agent-immobilized glass surface. The polymer brushes were crosslinked by photodimerization of the dimethylmaleimide moieties within polymer chains with stem cells present on the surface. In order to evaluate the effects of in situ photo-induced crosslinking of the polymer brushes on gene expression of stem cells, human bone marrow MSCs were cultured under static and dynamic culture conditions for 7 days. Expression of the osteocalcin (Ocn) gene in MSCs was used as an indicator of osteoblast differentiation under dynamic culture conditions. Structural conversion from non-crosslinked polymer brushes to crosslinked polymer brushes increased the expression of Ocn by 1.4-fold in the presence of adhered cells, compared with non-crosslinked polymer brushes under static culture conditions. These results suggest that MSCs recognized surface conversion from non-crosslinked to crosslinked structures, which resulted in altered differentiation lineages. Therefore, photo-crosslinkable surfaces with dimethyl maleimide moieties are potential novel materials for dynamically stimulating MSC differentiation.