The effect of cycling deflection on the injection-molded thermoplastic denture base resins

Objective. The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. Materials and methods. Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. Results. Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p < 0.05) with one polyamide based polymer (Valplast) and PMMA based polymers (Acrytone and Acron). The other polyamide based polymer (LucitoneFRS), polyester based polymers (EstheShot and EstheShotBright) and polycarbonate based polymer (ReigningN) did not show significant differences (p > 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. Conclusion. It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.     

Tumor necrosis factor alpha-induced endothelial tissue factor is located on the cell surface rather than in the subendothelial matrix

Because there is no consensus regarding the precise distribution of induced endothelial tissue factor (TF), we studied TF activity in and on tumor necrosis factor alpha-stimulated cultured human umbilical vein endothelial cells (ECs) and their underlying matrix. TF was mainly expressed on the cell surface. Only small traces were found on the apical surface suggesting that TF is predominantly located on the basolateral side of the cell membrane. The presence of TF on the cell surface was confirmed by flow cytometry. Subendothelial TF activity appeared to be dependent upon the procedure used to remove the stimulated EC monolayer. Whereas ammonium hydroxide or hypotonic lysis resulted in relatively high levels of matrix-associated TF, virtually no TF was found on the matrix after mild enzymatic detachment of stimulated ECs. Cell removal with EDTA resulted in intermediate levels of matrix-associated TF. Neither the enzymatic treatment nor EDTA degraded or removed this TF activity. Similar patterns were observed for matrix-associated TF antigen and EC surface markers. Electron microscopic analysis showed cell fragments on the matrix after monolayer lysis. The findings strongly suggest that induced endothelial TF associated with the subendothelial matrix actually represents TF on EC remnants.     

Indian Systems of Medicine: A Brief Profile

Medicinal plants based traditional systems of medicines are playing important role in providing health care to large section of population, especially in developing countries. Interest in them and utilization of herbal products produced based on them is increasing in developed countries also. To obtain optimum benefit and to understand the way these systems function, it is necessary to have minimum basic level information on their different aspects. Indian Systems of Medicine are among the well known global traditional systems of medicine. In this review, an attempt has been made to provide general information pertaining to different aspects of these systems. This is being done to enable the readers to appreciate the importance of the conceptual basis of these system in evolving the material medica. The aspects covered include information about historical background, conceptual basis, different disciplines studied in the systems, Research and Development aspects, Drug manufacturing aspects and impact of globalization on Ayurveda. In addition, basic information on Siddha and Unani systems has also been provided.     

Kinetics and bioavailability of N-nitrosodiethanolamine after intravenous and cutaneous administration to rats

Male CD-COBS rats were given N-nitrosodiethanolamine (NDELA) by intravenous or cutaneous administration at a dose of 5 mg/kg. Blood and liver were analysed for NDELA at various times after administration. The excretion of unchanged NDELA and its acidic metabolite N-(2-hydroxyethyl)-N-carboxymethylnitrosamine (ECMN) was determined in urine for 24 hr after treatment. The semilogarithmic blood concentration-time plot after iv injection showed a triphasic profile indicating that a three-compartment model may adequately describe the kinetics of this compound. After cutaneous application NDELA was rapidly absorbed through the skin, and the absolute bioavailability was calculated to be 27% from blood data, and to be 32% (NDELA + ECMN) from urine data. Hepatic NDELA levels reflected blood levels after both treatments, indicating that this organ does not accumulate NDELA to a significant extent. Urinary excretion of unchanged NDELA after iv and cutaneous administration was 83 and 25% of the administered dose, respectively. ECMN excretion was 4.9 and 2.5% of the administered dose after iv and cutaneous administration, respectively.     

Inhibition by indomethacin of increased estradiol extraction by the IUD-containing rat uterine horn

The role of prostaglandins on the extraction of estradiol (E2) by the rat uterine horn in the presence of the intrauterine device (IUD) was evaluated. Increased extraction of E2 by the IUD horn compared to the contralateral control horn was consistently observed irrespective of the estrogen status of the animals. This increased extraction was abolished by indomethacin, an inhibitor of prostaglandin synthesis, suggesting a role of prostaglandin in this process.