Effects of Ingredients on Thermal and Mechanical Properties of Acrylic Bone Cements

There is a very delicate relation between the amounts of all the ingredients present in the cement composition and the properties of the product. In this study, homogeneous poly(methyl methacrylate) (PMMA) microspheres were prepared by suspension polymerization technique, and used in cement formulations. Various acrylic cements with different compositions were prepared by using PMMA microspheres, methyl methacrylate (MMA) monomer, radiopaque agent of barium sulfate (BaSO4), inorganic particles of hydroxyapatite (HA), initiator and chain stopping agent of 1-dodecyl mercaptan (DDM). The effects of these additives on mechanical and thermal properties of the resultant cements were examined. Addition of 8% HA relative to the solid parts caused an increase in both tensile and compressive strengths from 20.40 to 25.20 MPa, and from 84.04 to 89.57 MPa, respectively, while curing temperature was decreased about 3 degrees. Chain stepping agent of DDM caused a sharp decrease about 30 degrees in the curing temperature. Radiopaque agent of barium sulfate caused inverse effect on mechanical and thermal properties. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 4077-4084, 200

Effects of resterilization on mechanical properties of polypropylene meshes

Background: The re-use of sterile packaged polypropylene meshes in hernia surgery is not recommended by the manufacturers. However, especially in developing and underdeveloped countries, many surgeons are obliged to re-use the mesh pieces after resterilization because of economic problems. The purpose of this study was to determine the effects of ethylene oxide and autoclave resterilization on the mechanical properties of polypropylene meshes

Pulley reconstruction with different materials: Experimental study

The digital fibroosseous Pulley system is essential for Optimum function of the flexor tendons and the continuation of normal hand functions. Different materials have been used for Pulley reconstruction in the literature but the ideal material is still controversial. In this study, after the excision of the A2 pulley, pulley reconstructions were performed by using acellular dermal matrix, solvent dehydrated bovine pericardium, fascia lata, and free tendon graft in the rabbit model. The animals were killed at the 8th and 12th weeks and subjected to biomechanical testing. Tendon excursion and work of flexion values were calculated for each digit of the rabbits. As a result, all the reconstructed pulleys were functioning well without a statistically significant difference between the experimental groups. Pulleys reconstructed with acellular dermal matrix and solvent-dehydrated bovine pericardium appear to have the potential to function as effective pulley substitutes

Essential Oil Composition, Antimicrobial and Cytotoxic Activities of Two Endemic Stachys cretica Subspecies (Lamiaceae) from Turkey

The chemical compositions of the water-distilled essential oil of Stachys cretica ssp. lesbiaca Rech. fil. and S. cretica ssp. trapezuntica Rech. fil. were determined by GC and GC MS. Altogether 63 compounds were identified. The sesquiterpene hydrocarbon, germacrene D (20.3% and 12.9% respectively) was the main component identified in both oils. Furthermore, ethanol, light petroleum, dichloromethane, ethyl acetate and n-butanol extracts prepared from the aerial parts of the plants were tested for their antimicrobial activities against six bacterial strains and the yeast Candida albicans. The extracts exhibited no antibacterial activity, but the light petroleum and n-butanolic fractions showed low antifungal activities. Crude ethanolic extracts of the two subspecies were tested for their ability to inhibit the growth of HL-60 and Ishikawa human tumor cell lines. The IC50 values were 100 mu g/mL for the HL-60 cell line and 200 mu g/mL for the Ishikawa cell line

How safe is the use of prosthetic materials in the repair of abdominal-wall defects in malnourished subjects?

Incisional hernias and abdominal-wall defects consume large amounts of healthcare resources. Use of mesh is effective in treatment of these disorders and can decrease the rate of recurrence. This experimental study focused on the safety of mesh use in the setting of malnutrition, a condition that impairs wound healing. Rats were divided into two groups: normally fed and food-restricted. An abdominal-wall defect, 2 by 2 cm, was covered with polypropylene mesh, 2.5 by 2.5 cm. After sacrifice of the rats at the 21st and 60th days, tissue samples were sent for tensiometric and histopathological studies. No significant difference in infectious complications was observed between the two groups. Tensiometry revealed no significant differences between the groups. On histopathological examination, the only difference noted was in the vascularization scores of normally fed rats. For malnourished subjects that survived after surgery, the use of polypropylene mesh appeared safe in the closure of abdominal-wall defects, with no increase in infection rate and satisfactory wound healing