Biomedical subjects

V Trinkaus-Randall

Publications and source records attributed to V Trinkaus-Randall.

44 records · Page 3Linked to original sources

PubMed1989

Modified hydroxyethylmethacrylate hydrogels as a modelling tool for the study of cell-substratum interactions.

The interactions between cells and their extracellular substratum environment are complex and difficult to study. Defined, synthetic substrata are valuable tools for experimentally determining the role of ionic and receptor-specific interactions between cells and their substrata. Hydrogels have been modified to contain stoichiometrically defined quantities of both positive and negative charge as well as specific proteins. These synthetic surfaces are water-rich matrices that possess hydroxyl groups, positive and negative ionized charges and native proteins, and can be considered as models of extracellular matrices on which an assessment of charge contribution and macromolecular content and specificity can be addressed with respect to cell-matrix interactions. This study shows that simple gels made of polyhydroxyethylmethacrylate do not support the spreading of cells but that the generation of copolymers by the addition of monomers that contain ionizable functional groups, will permit cell spreading. These simple modifications do not lead to cellular proliferation, yet when collagen is entrapped in the hydrogel substratum, proliferation occurs. The proliferative rate of cells grown on collagen-containing surfaces may be modified by altering the stoichiometry of the ionizable polymers used to make the surface. This study describes a synthetic, definable model for the study of cell-substratum interactions and control.

Acrylates↗

PubMed1989

Ultrastructural immunocytochemical localization of elastin in normal human trabecular meshwork.

Previous studies have suggested that hydrophobic moieties within the aqueous outflow channels might interact with certain aqueous components to retard outflow. While elastin is among the most hydrophobic proteins in the trabecular meshwork, it reacts poorly with conventional ultrastructural staining methods, so its potential role in regulating outflow could not be assessed. It was our goal to specifically localize elastin ultrastructurally using polyclonal antibodies against alpha elastin and its soluble precursor, tropoelastin. Human aorta served as a positive control. Preadsorption of the primary antibodies or their substitution with either normal rabbit serum or Tris buffer resulted in negligible labelling. With either antibody, only the electron-lucent elements in the center of elastic fibers of the trabecular meshwork were labelled, indicating that only these elements truly represent elastin. The pattern of elastin distribution within these fibers is most consistent with that found in tendons elsewhere in the body.

Adolescent↗

PubMed1988

Carbohydrate moieties of the basal lamina: their role in attachment and spreading of basal corneal epithelial cells.

Three lectins, Wheat germ agglutinin, succinyl Concanavalin A and Ricinus communis agglutinin were used to block specific sugar moieties in the basal lamina. Corneal epithelial basal cells were plated onto freshly denuded basal lamina. Attachment was studied by quantifying the adherence of prelabeled cells and by examining attachment sites using transmission electron microscopy. Spreading was examined using scanning electron microscopy. Attachment of the cells occurred within 15 min and spreading was apparent after 45 min. Both Wheat germ agglutinin and beta-N-acetylglucosaminidase inhibited cellular attachment. Succinyl Concanavalin A and Ricinus Communis agglutinin permitted attachment, but inhibited extensive cellular spreading. The results indicate that the attachment of basal cells is dependent on N-acetylglucosamine residues, and spreading is mediated by alpha methylmannoside, glucose, and galactose residues.

Animals↗

PubMed1988

Influence of substratum on corneal epithelial cell growth and protein synthesis.

To evaluate the effect of substratum on corneal epithelial cell growth and on protein synthesis, bacteriological dishes were coated with laminin, fibronectin, Type I collagen or Type IV collagen. Cell growth was enhanced by day 6 on both laminin and Type I collagen substrata. Adhesion sites and parallel microfilament arrays were present only on cells cultured on laminin coated substratum. The synthesis of connective tissue and cytoskeletal proteins was influenced by the four different substrata. Both the time course and the amount synthesized was affected. The results of this study indicate that the substratum plays a significant role in regulating the synthesis of specific proteins.

Animals↗

PubMed1988

Development of a biopolymeric keratoprosthetic material. Evaluation in vitro and in vivo.

Based on the results of in vitro and in vivo experiments, we have determined that the optimal material for the central transparent portion of a perforating keratoprosthesis is a polyvinyl alcohol copolymer hydrogel. The material supports the maintenance and growth of corneal epithelium in vitro as shown by population doublings and transmission electron microscopy. Discs preseeded with epithelial cells were cultured in vitro and transplanted into rabbit corneas. The proliferation of these cells in vivo was demonstrated using 3H-thymidine. Other experiments showed that the preseeded cells not only migrated from the central disc onto the peripheral rim of the host cornea but also that host peripheral epithelial cells migrated onto the anterior surface of the disc. The experiments described in this paper demonstrate that corneal epithelial cells preseeded onto hydrogel discs and transplanted into rabbit corneas remain adherent and are capable of proliferating.

Animals↗

PubMed1985

A technique for obtaining basal corneal epithelial cells.

A technique has been developed for obtaining a cell suspension enriched (89%) in basal corneal epithelial cells. Eleven millimeter corneal buttons were removed and placed in culture medium containing low (10 microM) calcium. The posterior half of the stroma was removed with forceps. Three superficial cuts were made with a Bard-Parker blade on the anterior half of the cornea, which was then incubated for 18 hr at 35 degrees C. Nonadherent cells were brushed off after the incubation and basal cells were harvested after a 1-hr incubation in Dispase II. Cell viability estimated by Erythrocin beta exclusion was 90%. Further evidence of viability was that the cells adhered to their native substrate, the denuded basal lamina. The authors protocol provides a method for analyzing the biochemistry of a known population of epithelial cells and makes available a defined source of cells for culture.

Animals↗

PubMed1984

Role of calcium and calmodulin in hemidesmosome formation in vitro.

Intact epithelial sheets were removed from rabbit corneas using Dispase II, a bacterial neutral protease. The freed sheets were placed on denuded corneal basal laminae and incubated at 35 degrees C for 3, 6, 18, or 24 h. Epithelial-basal lamina preparations were incubated in culture medium that either contained (a) varying concentrations of Ca2+ ions, (b) calmodulin antagonists, (c) exogenous calmodulin following an initial 6-h incubation in the presence of antagonists, or that lacked (d) Mg2+ ions. Tissues were processed for electron microscopy, and micrographs were taken of basal cell membranes. At least four experiments were conducted for each treatment, and for each experiment the total number of hemidesmosomes were counted along the basal membrane-basal lamina surface of eight cells. The number of hemidesmosomes formed was directly proportional to the increasing concentration of Ca2+. The presence of absence of Mg2+ ions did not change the numbers of hemidesmosomes formed. Calmodulin antagonists inhibited hemidesmosome formation, and this inhibition was reversed by the addition of calmodulin. Thus, hemidesmosome formation is Ca2+ dependent and appears to be mediated by a calmodulin-regulated mechanism.

Animals↗

PubMedDate not supplied

The intracellular distribution of vinculin and alpha 2 integrin in epithelial cells and chondrocytes.

The purpose of this study was to demonstrate the presence of vinculin and alpha 2 integrin in chondrocytes in situ and epithelial cells. We also determined that the appropriate fixation and extraction protocols for immunohistochemistry and laser scanning confocal microscopy for an integral membrane protein and an actin-associated protein in cultured cells and whole tissue was different. Cultured epithelial cells, whole mount human cornea and avian cartilage were fixed and prepared using a number of standard procedures used for indirect fluorescence immunohistochemistry. The distribution of vinculin was cell-type and fixation-specific. Chondrocytes and cultured epithelial cells demonstrated vinculin in areas that appear to be associated with filamentous actin. Vinculin was associated with cell membranes in human cornea. The expression of alpha 2 integrin observed in chondrocytes fixed with methanol, paraformaldehyde, or formaldehyde is consistent with its role in cell-substrate interaction, but may also suggest a role in dividing and differentiating cells. The localization of alpha 2 integrin in human corneal epithelia supports its role as a cell-cell adhesion molecule. The cytoplasmic distribution of vinculin and alpha 2 integrin in tissues fixed without detergent extraction suggests that the fixation step may be sufficient for antibody penetration and antigen extraction. These studies are the first report of vinculin and alpha 2 integrin in embryonic chondrocytes. In addition we have shown that confocal laser scanning microscopy combined with proper fixation and extraction protocols may optimize the localization of antigens in cultured and whole mount cells.

Animals↗