Development of a conjunctival tissue substitute on the basis of plastic compressed collagen.

Ocular surface disorders, such as pterygium, cicatricial pemphigoid and external disruptions, can cause severe inflammation, scarring, fornix shortening as well as ankyloblepharon. Current treatments do not resolve these conditions sufficiently. The aim of this study was to evaluate clinical applicability and suitability of plastic compressed collagen to serve as a substrate for the expansion of human conjunctival epithelial cells in order to develop an epithelialized conjunctival substitute for fornix reconstruction. Human conjunctival epithelial cells were expanded on plastic compressed collagen gels. Epithelial cell characteristics were evaluated by haematoxylin and eosin staining, electron microscopy and cytokeratin expression. The expression of putative epithelial progenitor cell markers p63α, ABCG2 and CK15 was assessed by immunostaining. The proliferative capacity and clonal growth of the cells was evaluated before (P0) and after expansion (P1) on the plastic compressed collagen gels by colony forming efficiency assay. The potential clinical applicability of this gel substitutes was evaluated by assessment of their biomechanical properties as well as their surgical handling. Human conjunctival epithelial cells cultured on plastic and plastic compressed collagen gels formed a confluent cell layer and expressed CK19. The cells showed expression of the putative epithelial progenitor cell markers p63α, ABCG2 and CK15 and sustained colony forming ability. The compressed collagen gels showed a high ultimate tensile strength and elasticity and the surgical handling of gels was comparable to amniotic membrane. An epithelialized conjunctival tissue construct on the basis of compressed collagen might therefore be a promising alternative bioartificial tissue substitute for conjunctival reconstruction. Copyright © 2015 John Wiley & Sons, Ltd.

The relationship between contact lens surface charge and in-vitro protein deposition levels.

The adsorption of lysozyme and human serum albumin (HSA) onto hydrogel contact lenses was investigated as a function of lens surface charge. Anionic, cationic and non-ionic contact lenses were deposited using single protein solutions of identical pH and osmolarity. Protein deposition was analyzed using matrix assisted laser desorption ionization mass spectrometry (MALDI-ToF MS) and compared to a direct UV protein analysis method, the bicinchoninic acid (BCA) assay. The results showed remarkable consistency between the two techniques. By inference of results from analyses of sample solutions, lysozyme, a positively charged protein at physiological pH, was only detected on the anionic surface charged contact lenses, presumably a result of electrostatic interactions. Neither the cationic nor the non-ionic lenses deposited lysozyme, possibly due to charge repulsion. HSA, a negatively charged protein at physiological pH, was detected on the cationic lenses, again as a result of electrostatic interactions. The fact that HSA was not observed on either the anionic or non-ionic charged species further demonstrates the effect of charge repulsion.

Limitations of the evaluation of adnexal masses by its macroscopic aspects, cytology and biopsy.

To investigate the relevance of intraoperative macroscopic evaluation of adnexal masses a prospective study was conducted from June 1st, 1993 to May 31st, 1994, which included 57 premenopausal and 60 postmenopausal women, who underwent laparotomy because of a cystic adnexal mass. The surgeons were asked to classify the tumor intraoperatively as benign or malignant and to assign to histologic groups. In addition cytology of the cyst fluid and a biopsy from the cystic wall were evaluated. Comparison of these items with the results of permanent section diagnosis revealed the tendency of the surgeons to underestimate adnexal masses depending on patients' age and the complexity of the tumor, despite of the knowledge of preoperative ultrasonographic findings. Sufficient cytolologic examination was possible in only one third of aspirates and only 21% of the examined postmenopausal malignant neoplasms have correctly been diagnosed by cytology. Evaluation of the biopsy specimens demonstrates a marked percentage of false negatives with respect to benign tumors (30% of non-functional benign neoplasms in the premenopause were assessed as functional cysts) as well as malignant neoplasms (only 72% were diagnosed correctly in the postmenopause group). In conclusion intraoperative subjective assessment, cytology and representative biopsies do not necessarily concur with the definitive histological diagnosis.

Surface chemical structure for soft contact lenses as a function of polymer processing.

The surface chemistry and topography of cast-molded Etafilcon-A and doubled-sided lathed Etafilcon-A soft contact lenses were determined to be significantly different. The variations in surface chemical and morphologic structure between the two lenses were the result of contact lens manufacturing methods. The surface of the cast-molded Etafilcon-A had a consistently less rough surface compared to the doubled sided lathed Etafilcon-A as determined by atomic force microscopy. The surface of the doubled sided lathed Etafilcon-A contained primarily silicone and wax contamination in addition to minute amounts of HEMA. The cast-molded Etafilcon-A had an elemental and chemical content which was consistent with the polymer stoichiometry. Contact angle wettability profiles revealed inherent wettability differences between the two lenses types. The cast-molded Etafilcon-A had an inherently greater water wettability, polarity, and critical surface tension. This means that these two lenses cannot be compared as similar or identical lens materials in terms of surface composition. The manufacturing method used to produce a soft contact lens directly determines the surface elemental and chemical structure as well as the morphology of the finished lens material. These results suggest possible differences in the clinical comfort, spoilage, and lubricity felt during patient wear.

Angular dependent ESCA and infrared studies of segmented polyurethanes.

The understanding of surface bonding and composition of complex polymer mixtures used for biomedical implant materials can be accomplished by a combination of techniques. In this study, vibrational spectroscopic probes of bulk and surface bonding and composition are combined with measurements with angular dependent X-Ray Photoelectron Spectroscopy (XPS or ESCA). These data provide a detailed description in the surface composition of Biomer and Avcothane, commercially available biomedical grade polymers and model systems polydimethylsiloxane (DMS) and Avcomat, all of which have been cast as smooth films from solution. Impurities are observed segregated in the near surface region sampled by ESCA which are not observed in the surface infrared results. Both Attenuated Total Reflectance (ATR) and Photoacoustic (PA) sampling are utilized, ATR to provide a depth profile and demonstrate the higher surface sensitivity of PA sampling. The combined results describe the depth of segregation of DMS blocks in Avcothane, the presence of DMS within the topmost 20 A in Biomer, and similar impurities in the model polymers. These results point out the need for multitechnique approach and the control of sample preparation and morphology in understanding complex polymer surfaces.