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Six different cross-linking agents were added to the monomer component of an autopolymerizing denture base resin, and their effects on the water sorption and solubility were investigated. The results of this study suggested that the chemical nature of the polymer versus that of the water molecule directly affected the water sorption of denture base resin. The addition of a cross-linking agent decreased the solubility with increasing concentration.

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The authors investigated the composition and structure of six hard auto-polymerizing reline resins. The chemical compositions, glass transition temperatures, molecular weights and particle size distributions of the powders, and the chemical compositions of the liquids were examined. The powder compositions were classified into three groups. The first group contained poly(methyl methacrylate). The second contained poly(ethyl methacrylate) and poly(methyl methacrylate/ethyl methacrylate) and the third contained poly(ethyl methacrylate). The average molecular weights of these powders was about 2 x 10(5). The indexes of molecular weight dispersion suggested that all powders contained polymers that had a narrow molecular weight distribution. The particle size distribution of these powders was classified into two groups. The first group was mainly in the range of 50-100 microns and the second mainly between 20 and 50 microns. The composition of the liquids was classified into three groups. The first group contained a monofunctional methacrylate monomer. The second contained a monofunctional methacrylate monomer and a plasticizer and the third contained monofunctional methacrylate monomers and cross-linking agents. The results of this experiment showed the differences in composition among the products. This will be useful for examining the relationship between the composition and mechanical properties of hard autopolymerizing reline resins.

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The use of 2-hydroxyethyl methacrylate (HEMA)-based polymer as a biocompatible material has been well-established. HEMA-based resins containing cross-linking agents have several potential clinical applications. It is hypothesized that the incorporation of cross-linking agent will improve the mechanical properties of HEMA-based polymers while reducing water absorption and solubility. The purpose of the work reported here was to test this hypothesis and to determine the most effective cross-linking agent. A relationship among flexural strength, modulus, water absorption and solubility, and concentration of cross-linking agent was demonstrated. Strength and modulus tend to increase as the cross-linking agent concentration is increased, up to about 50%, after which the values level out or begin to fall. Water absorption drops with increasing cross-linking agent over the whole range of concentrations. Solubility tends to show a small decrease initially (up to 40%), followed by a noticeable increase as cross-linking agent concentration is increased. The trends were similar for all cross-linking agents, although there were differences in the absolute values in all properties depending upon the type of cross-linking agent used.

A disintegrin and metalloproteases (ADAM) are cell membraneanchored proteins with potential implications for the metastasis of human cancer cells via cell adhesion and protease activities. In prostate cancer (PC), the ADAM-10 protein showed a nuclear localization whereas in benign prostate hypertrophy (BPH) it was predominantly bound to the cell membrane. We hypothesized that the pathogenesis and progression of PC are attributable to the nuclear translocation of ADAM-10. Immunoblotting revealed that after 5α α α α-dihydrotestosterone treatment, a 60-kDa active form of ADAM-10 was increased in the nuclear fraction but decreased in the cell membrane and cytoplasmic fractions of human androgendependent PC cells. Immunocytochemistry revealed that after 5α α α α-dihydrotestosterone treatment, the ADAM-10 protein was translocated from the cell membrane to the nucleus. Coimmunoprecipitation of androgen receptor and ADAM-10 was detected in the nuclear fraction but not in the cell membrane and cytoplasmic fractions. Immunohistochemical study of 64 PC and 20 BPH samples showed that the intensity of ADAM-10 staining was significantly higher in the nuclei of PC cells than in the nuclei of BPH cells (P < 0.0001). It was also significantly lower in the cell membrane of PC cells than in the cell membrane of BPH cells (P = 0.0017). Nuclear staining intensity was significantly correlated with the clinical Tfactor (P = 0.004), the Gleason score (P < 0.0001) and preoperative prostate-specific antigen levels (P = 0.0061). ADAM-10 small interfering RNA transfectants showed a significant decrease in cell growth compared to the controls. Our results suggest that in human PC, the nuclear translocation of ADAM-10 coupled with the androgen receptor is involved in tumor growth and progression. (Cancer Sci 2007; 98: 1720-1726) A disintegrin and metalloproteases (ADAM) are members of the metzincin (zinc-dependent metalloprotease) superfamily. They are cell membrane-anchored cell surface proteins involved in the proteolytic processing of other transmembrane proteins, in cell adhesion and in cell signaling events.(1-3) Among the more than 30 characterized ADAM proteins, ADAM-9, -10 and -17 act as cell surface 'sheddases', cleaving the extracellular (ecto) domains of cell membrane-bound proteins, including amyloid precursor proteins that have been investigated in Alzheimer's disease.(4) These ADAM are highly expressed in human breast, lung, stomach, colon, pancreas, uterine, ovarian and prostate cancer.(5-11) They activate growth factors such as epidermal growth factor and transforming growth factor-α, cytokines such as tumor necrosis factor-α, and degrade cell adhesion molecules such as CD44, L1 and collagens, all of which are synthesized as precursors and are responsible for cancer development. (12,13) Prostate cancer (PC) is one of the most common malignancies among men. Global cancer statistics indicated that in 2002, 5.8% of cancer deaths in men and 3.3% of all cancer deaths were attributable to PC. (14) In the development of PC, 5α-dihyd...