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.     

Postural activity in the muscles of mastication with the subject upright, inclined, and supine

Abstract— With the mandible at rest, electromyographic recordings were obtained from the anterior temporal, lateral pterygoid, and digastric muscles with the subjects (A) sitting upright with the head unsupported, (B) inclining backwards with the back-rest at an angle of 45°, and (C) supine. Two minutes after a shift in posture the electrical activity in the anterior temporal muscles was strongest in the upright position, it decreased slightly when the back-rest was at 45°, and was least in the supine position. The digastric muscles showed a pattern similar to that of the temporal. The activity in the lateral pterygoid muscles was strongest when the subject was inclined backwards at 45°. The influence, therefore, of these muscles on the posterior border position of the mandible varies with posture. In all the muscles studied there was least activity when the subject was in the supine position. This would suggest that the supine position is suitable for recording the most retruded position of the mandible. In the intermediate position the lateral pterygoid muscles appear to counteract retrusion.     

UNPREDICTABILITY OF REGRESSION OF ANALGESIA DURING THE CONTINUOUS POSTOPERATIVE EXTRADURAL INFUSION OF BUPIVACAINE

Twenty-four otherwise healthy patients scheduled for electivemajor abdominal surgery received general anaesthesia plus lumbarextradural analgesia. A loading dose of 0.5% plain bupivacainewas given to produce sensory analgesia (pin prick) from T4 toS5 and followed by a continuous infusion of 0.5% plain bupivacaine8 ml h^–1. Pain, scored on a 5-point scale, and sensoryanalgesia were assessed hourly for 16 h after skin incision.If sensory analgesia decreased by more than 5 segments fromits preoperative level, or if the pain score reached 2 (moderatepain), the patients were removed from the study, and pain wastreated otherwise. Only three patients maintained their initiallevels of sensory analgesia and a pain score of less than 2.In the remaining patients sensory analgesia decreased at least5 segments or pain score reached 2 between 4 and 16h after skinincision. We found a weak correlation between increasing ageand the duration of sensory analgesia (r=0.46, P<0.05), butno significant correlations between duration of sensory analgesiaand sex, weight, height, body surface area, serum albumin concentration,duration or site of operation.