Immunolocalization of prolyl 4-hydroxylase in rabbit lens epithelial cells

N-acetyl cysteine (NAC)-assisted detoxification of PMMA resin

Despite its proven cytotoxicity, poly-methyl methacrylate (PMMA) resin is one of the most frequently and extensively used materials in dental practice. This study hypothesized that an anti-oxidant amino acid, N-acetyl cysteine (NAC), has the potential to detoxify this material. Ten percent of the rat dental pulp cells were viable when cultured on the PMMA resin for 24 hours, while over 70% of the cells were viable on the NAC-added resin. Nearly all suppressed alkaline phosphatase activity, matrix mineralizing capability, and odontoblastic gene expression, such as dentin sialoprotein, on the untreated control resin was recovered by NAC in a concentration-dependent manner. A Ca/P ratio of 1.65 was found in the extracellular matrix of cultures on NAC-added resin, while that in the untreated resin culture was 0.70. The addition of NAC to PMMA resin significantly ameliorated its cytotoxicity to the dental pulp cells and restored their odontoblast-like cell phenotype to a biologically significant degree.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Adhesion of soluble fibronectin, laminin, and collagen type IV to intraocular lens materials

PURPOSE

To evaluate soluble fibronectin, laminin, and collagen IV adhesion to poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, silicone, acrylate, and hydrogel intraocular lenses (IOLs).

SETTING

Department of Medical Biochemistry, University of Oulu, Oulu, Finland.

METHODS

Seventy-five IOLs were incubated for 24 hours at 37 degrees C with radioactive iodine labeled soluble fibronectin, laminin, or collagen type IV. Twenty-five IOLs were analyzed for each protein, 5 of each type. The amount of absorbed protein was measured with a gamma counter and expressed as counts per minute (cpm).

RESULTS

Fibronectin bound best to the acrylate IOL; the differences between the acrylate and the other materials, except PMMA, were significant (P < .01 to .001; PMMA P = .31). Although significantly more laminin bound to acrylate than to PMMA, HSM PMMA, or silicone (P < .05 to .001), hydrogel had the highest overall binding of this protein (P < .001 to .0001). Hydrogel also had significantly higher binding of type IV collagen than the other IOLs (P < .01 to .0001).

CONCLUSIONS

It can be hypothesized that if an IOL has more fibronectin bound to it, the IOL can also attach to the capsule better as it consists mainly of collagen. The stronger binding of fibronectin and laminin to acrylate IOLs could be an explanation for the better adhesion of the acrylate IOL to the anterior and posterior capsules and thus for the lower rate of posterior capsule opacification.