Cell Succinate Dehydrogenase Activity Research Articles

Cytotoxicity of endodontic sealers after one year of agingin vitro

The in vitro cytotoxic response to endodontic sealers was assessed for one year. AH-Plus (AHP), Epiphany (EPH), EndoRez (ER), Guttaflow (GF), InnoEndo (IN), and Pulp Canal Sealer (PCS) were exposed to mouse osteoblasts and human monocytes after curing, 52 weeks of aging, and after resurfacing post-aging; cellular response was estimated by succinate dehydrogenase (SDH) activity. The effect of materials on TNFα secretion from activated (LPS) and inactivated monocytes also was measured. Cell responses were compared with ANOVA and Tukey post hoc analysis (α = 0.05). Initially, all materials except GF suppressed osteoblastic SDH activity compared with Teflon (Tf) controls. SDH activity in cells exposed to some aged sealers improved significantly; but IN and ER remained cytotoxic. When aged materials were resurfaced then tested, AHP, ER, GF, and IN did not change. EPH and PCS were more toxic. Monocytes responded similarly to the osteoblasts. No endodontic sealer activated monocytic TNFα secretion (p > 0.05 vs. -LPS Tf-controls). LPS-activated monocytes exposed to unresurfaced AHP and IN significantly suppressed TNFα secretion. When activated monocytes were exposed to the resurfaced sealers, differential suppression of TNFα secretion was observed for three of the four sealers tested (EPH, IN, and PCS). The results suggest that long-term aging may be a useful adjunct to in vitro assessment of these materials.

In vitro cytotoxicity of a remineralizing resin-based calcium phosphate cement

Recently, a resin-based calcium phosphate cement (RCPC) has been reported as a remineralizing pulp-capping or lining cement. RCPC consists mainly of tetracalcium and dicalcium phosphates, ethoxylated bisphenol A dimethacrylate and pyromellitic glycerol dimethacrylate monomers and photo- and chemical initiators. Here, the cytotoxic effects of RCPC were evaluated. The hypothesis was that RCPC induced only minor cytotoxic response in immortalized murine odontoblast and pulp cells, comparable to that produced by similar dimethacrylates due to unpolymerized dimethacrylate monomer present after curing. Cytotoxicity was determined following the changes in cell succinate dehydrogenase activity after 24 h exposure to the cement components and after a 24 h recovery period. A fourfold range of concentrations was tested of the monomers, the eluate of cured RCPC leached in Dulbecco's modified Eagle's medium, and crushed cured cement in dimethyl sulfoxide. The monomers themselves had cytotoxicities similar to those reported for other dimethacrylates, although they are significantly less toxic than Bis-GMA. Differential cell sensitivity was demonstrated, with the pulp cells having greater sensitivity to the unpolymerized monomer than the odontoblast-like cells. The leached components have cytotoxicity similar to that of the free monomers. The crushed material demonstrated no apparent cytotoxicity at the dilutions tested. These data demonstrate that RCPC has an in vitro cytotoxicity that is comparable to other materials containing dimethacrylate monomers and suggest that the material may be suitable for use in dental restorations. The data also indicate that the pulp cells appear more sensitive to dimethacrylates than the odontoblasts.

Modulation of liver-specific cellular response to ethanol in vitro in hep G2 cells

The aim of this study was to investigate in vitro in a human hepatoblastoma cell line, Hep G2, the effect of ethanol (EtOH) toxicity. The ultrastructural changes were assessed by performing quantitative light and transmission electron microscopy. The second objective of this study was to define further EtOH-induced biochemical changes associated with mitochondrial function. In comparison with controls, after exposure to 80 mm EtOH cells showed: a threefold increase in length of mitochondria; proliferation, vesiculation and dilatation of smooth endoplasmic reticulum, and twofold increases in the size of lipid droplets and in their number/cell. Exposure of cells to two doses of EtOH augmented the ultrastructural alterations observed after a single dose. Cytoviability, assessed by metabolism of methylxanthine dye decreased significantly by ( P < 0.0001) to 68% of the control after one dose and was further reduced after the second dose of EtOH ( P < 0.001). Succinate dehydrogenase activity in cells treated for 24 hr with 80 mm EtOH was decreased to about 80% of control values after one 24-hr treatment with 80 mM EtOH and to about 55% of control values after two 24-hr exposures. This in vitro model of ethanol-induced cytotoxicity in Hep G2 cells is able to reproduce essential ultrastructural features of alcohol-related hepatitis, in humans, including steatosis and dose-dependent hepatocytotoxicity. The present work represents the first morphometric study to measure changes produced by EtOH exposure in human-derived liver cells.

In vitro succinate dehydrogenase chemosensitivity of gastric carcinoma?relationship to DNA content

Relationships between in vitro chemosensitivity and cell nuclear DNA content were investigated in malignant cells from 41 patients exhibiting advanced gastric carcinoma. The chemosensitivity was evaluated by measuring the succinate dehydrogenase (SD) activity in drug-exposed cancer cells and the DNA content was microspectrophotometrically determined. Following exposure of malignant tissue to carboquone (CQ) and cisplatin (DDP), the mean SD activity in cells displaying a relatively regular DNA distribution (type II) was significantly higher than that in those exhibiting a widely scattered DNA distribution (type IV; P less than 0.01 in CQ, P less than 0.05 in DDP). A similar tendency was recognized in cells that were treated with aclacinomycin A (ACR), Adriamycin (ADM), and mitomycin C (MMC). Such a decrease in SD activity in cells exhibiting a type IV pattern was remarkable, especially in cases undifferentiated adenocarcinoma. Mitotic counting analysis revealed a significantly higher value for DNA pattern type IV as compared with the findings for type II (P less than 0.01). These results demonstrate that gastric carcinoma displaying a high malignant potentially shows a better response to antitumor drugs. Adjuvant chemotherapy prescribed following drug-sensitivity testing should be effective against such tumors.