Restless legs syndrome effectively treated with constant-pressure predilution online hemodiafiltration

Journal of Artificial Organs - We encountered a case of unstable predilution online HDF due to elevated transmembrane pressure (TMP) when performing constant-speed predilution online...     

Immobilization of octadecyl ammonium chloride on the surface of titanium and its effect on microbial colonization in vitro

The aim of our study was twofold: to immobilize an organosilicon quaternary ammonium salt (3-(trimethoxysilyl)-propyldimethyl-octadecyl ammonium chloride, Si-QAC) on the surface of pure titanium and to investigate the antimicrobial activity of Si-QAC-immobilized titanium against microbial adherence and biofilm formation. The results of ToF-SIMS analysis of Si-QAC-titanium suggested the possibility of immobilizing Si-QAC on titanium surface through Ti-O-Si coupling, and that Si-QAC treatment significantly reduced both the adherence and colonization of Candida albicans and Streptococcus mutans isolates. The antimicrobial activity was achieved through at least two mechanisms: the first was attributed to the octadecyl alkyl chain which inhibited initial adherence, and the second was attributed to the quaternary ammonium salt which killed initial adherent cells as well as retarded or inhibited subsequent microbial growth. Further, thermocycling did not significantly reduce the antimicrobial activity of Si-QAC-titanium, and no significant cytotoxicity of Si-QAC-titanium was observed in either cell viability test or proinflammatory cytokine production test using human gingival fibroblasts. These results, taken together, favorably suggested that Si-QAC treatment would be a helpful means to inhibit dental plaque or denture plaque formation.     

Regulation of glycosaminoglycan synthesis by parathyroid hormone and prostaglandin E2 in cultured dental pulp cells.

The effects of parathyroid hormone (PTH) and prostaglandin E2 (PGE2) on glycosaminoglycan (GAG) synthesis in bovine dental pulp cells were studied. Dibutyryl cyclic adenosine 3',5'-monophosphate and isobutyl methylxanthine were used to assess whether their effects were mediated by intracellular cAMP. Glycosaminoglycan synthesis was assayed by measuring [35S]sulfate incorporation into the GAG fraction of dental pulp cells. Glycosaminoglycan synthesis was increased 1.3-fold by PTH (4 units per ml) alone, 1.6-fold by PTH in the presence of isobutyl methylxanthine, 1.2-fold by PGE2 (100 ng per ml) alone, and 1.5-fold by PGE2 in the presence of isobutyl methylxanthine. Dibutyryl cyclic adenosine 3',5'-monophosphate enhanced GAG synthesis in a concentration-dependent manner and mimicked the effects of PTH and PGE2. The effects of these hormones on pulp and gingival cells were compared; addition of PTH, PGE2, and dibutyryl cAMP had no effect on gingival cell GAG synthesis, whereas their addition induced significant increases of GAG in pulp cells. These results indicate that PTH and PGE2 are involved in the differentiation of dental pulp cells and that these effects are mediated by cAMP.     

Accuracy of complete dental arch impressions and stone casts using a three-dimensional measurement system. Effects on accuracy of rubber impression materials and trays

The purpose of this study was to investigate and compare the accuracy of complete dental arch impressions and stone casts made with two kinds of impression materials (addition-type silicone and polysulfide rubber) and trays (custom tray and modified custom tray). In addition, the effect of the quantity of stone was examined. Impressions were made from a metallic model of a simplified maxillary dentition. Impressions and stone casts were measured respectively with a three-dimensional measuring microscope. The results were as follows: 1. Distortions of impressions were so small that the reproducibilities of impressions were superior three-dimensionally. These kinds of impressions and trays did not influence the accuracy of impressions. 2. The setting expansion of the stone in the impression occurred in the outward direction and was affected by the kinds of impressions and trays. 3. The arch widths and lengths of the stone casts tended to increase in number. 4. Stone casts made with addition-type silicone impression material and a custom tray were the most accurate because the combination of the impression material and tray effectively suppressed the setting expansion of stone. 5. The accuracy of stone casts could be improved by controlling the quantity of stone.     

Identification of calprotectin, a calcium binding leukocyte protein, in human dental calculus matrix

Calprotectin is a calcium binding protein produced by leukocytes, macrophages and epithelial cells, and its levels in several tissues increase during infections and in many inflamed areas, suggesting that it may be an indicator of inflammatory activity. Osteopontin is a prominent phosphorylated glycoprotein in bone matrix, having calcium binding capacity. Recently, it has been reported that calprotectin and osteopontin are present in urinary stones (pathological mineralized masses in the body), and that these proteins may be involved in their formation. Dental calculus formed by mineralization of dental plaque is an inflammatory factor which may contribute to periodontal disease. It contains many organic components involved in mineralization. We recently found osteopontin molecules in human dental calculus and suggested that the components of its matrix may be similar to those of urinary stones. In this study, we investigated the presence of calprotectin in human dental calculus by immunohistochemical and immunoblotting analyses using a specific antibody for calprotectin. After fixation and demineralization of dental calculi adhered to tooth roots, sections embedded in paraffin were immunoreacted with the antibody for calprotectin and positive immunostaining for calprotectin was observed. Dental calculus proteins were then extracted with EDTA and separated by electrophoresis on 15% polyacrylamide gels. By immunoblotting analysis, 3 or 4 bands were observed at 11, 14.5, 22–25, 28 or 36.5 kDa and these patterns corresponded to those of calprotectin subunits. When non-immune rabbit serum was used instead of calprotectin-specific antibody as a negative control, no immunoreactivity was observed. These findings indicate that calprotectin is associated not only with antibacterial action but also with calcium binding capacity during dental calculus formation.     

Actions of parathyroid hormone on cultured human dental pulp cells.

The responsiveness of human dental pulp (HDP) cells to parathyroid hormone (PTH) was investigated by measuring their cyclic AMP (cAMP) content, DNA synthesis, alkaline phosphatase activity, collagen synthesis, and glycosaminoglycan (GAG) synthesis. PTH dose-dependently increased the intracellular cAMP 1 min after the addition of PTH. Confluent HDP cells on day 14 expressed a high level of cAMP production after addition of 3 units/ml PTH. The hormone did not affect DNA synthesis by HDP cells. Alkaline phosphatase activity was suppressed by PTH to 81% of control (p < 0.01), and addition of dibutyryl cAMP to the medium mimicked the effect of PTH (79% of control, p < 0.01). The hormone inhibited collagen synthesis (15% decrease of [3H] proline incorporation, p < 0.01), and stimulated non-collagen protein synthesis (10% increase, p < 0.05). The increase of non-collagen protein by PTH was in accordance with the enhancement of GAG synthesis (17% increase of [35S]sulfate incorporation, p < 0.01). Dibutyryl cAMP caused further increase of GAG synthesis, to 155% of control (p < 0.01). Observations of the radiolabeled proteins on 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis after metabolic labeling with [14C]proline and [35S]sulfate revealed a similar tendency to the quantitative determinations in which PTH inhibited collagen synthesis and stimulated GAG synthesis. These findings suggest that HDP cells have some osteoblastic characteristics in terms of PTH responsiveness, and that this culture system is a useful model for studies of human dental pulp.     

Effects of insulin and parathyroid hormone on DNA synthesis and ornithine decarboxylase activity in cultured bovine dental pulp

The effects of insulin and parathyroid hormone (PTH) on the proliferation of developing bovine dental pulp in an explant culture system were studied. Dental pulp explants were cultured on siliconized lens paper floating on the serum-free medium for up to 72 h. Ornithine decarboxylase (ODC) activity increased and reached a peak after 24 h. DNA synthesis increased continuously after a lag period of 24 h. Insulin (10 milliunits per ml) stimulated ODC activity 1.3-fold and DNA synthesis 1.5-fold. PTH alone (1 unit per ml) stimulated ODC activity in 1.7-fold, but did not affect DNA synthesis. PTH plus insulin caused greater increases in ODC activity and DNA synthesis in dental pulp explants than insulin alone (ODC, 2.6-fold; DNA, 3.7-fold). These results suggest that insulin and PTH are involved in the regulation of growth of dentinogenically active bovine dental pulp.