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Biomedical subjects

B Faris

Publications and source records attributed to B Faris.

At least 55 records · Page 3Linked to original sources
PubMed1984

Ultrastructural studies of attachment site formation in aortic smooth muscle cells cultured on collagen-hydroxyethylmethacrylate hydrogels.

Hydroxyethylmethacrylate (HEMA) hydrogels have a peculiar crater-like topography which renders them ideal for studying cell-to-substrate contact formation. The hydrogel is quite suitable for such studies since it is transparent, which allows for light microscopic observations, it is not toxic, and it will support cell growth only when an additional protein component such as collagen is integrated into its surface. Cultured rabbit aortic smooth muscle cells (SMC) were grown on collagen-HEMA hydrogels, and the ultrastructure of developing cell attachment sites was studied. By 3 hr after cell seeding, both the rounded and the spreading SMC appeared anchored to the hydrogel via extracellular connective tissue-like material. The fully formed attachment site present at 5-8 days was characterized by large bundles of intracellular myofilaments inserting onto areas of increased electron density along the plasmalemmal membrane; large amounts of extracellular connective tissue-like material also appeared attached to the areas of increased electron density. Fully formed cell substratum attachment sites were not observed when either elastin-HEMA hydrogels or hydrogels polymerized in the absence of protein were employed.

Actin Cytoskeleton↗
PubMed1984

Mammalian cell growth on collagen-hydrogels.

Hydroxyethylmethacrylate (HEMA) hydrogels have a peculiar crater-like topography which renders them ideal for studying cell-to-substrate contact formation. Cultured rabbit aortic smooth muscle cells (SMC) were grown on collagen-HEMA hydrogels, and the ultrastructure of developing cell attachment sites was studied. By 3 hours after cell seeding, both the rounded and spreading SMC appeared anchored to the hydrogel via extra-cellular connective tissue-like material. The fully formed attachment site present at 5-8 day was characterized by large bundles of intracellular myofilaments inserting onto areas of increased electron density along the plasmalemmal membrane. Large amounts of extracellular connective tissue-like material also appeared attached to the areas of increased electron density. Fully formed cell substratum attachment sites were not observed when either elastin-HEMA or hydrogels polymerized in the absence of protein were employed. The growth and collagen synthesis by human embryonic lung fibroblasts (IMR-90) and endothelial cells on collagen-HEMA hydrogels and tissue culture plastic were also examined. Although the two cell types grew equally well on the two surfaces, differences in protein synthesis were observed. The procollagen Type I and III ratio synthesized by the fibroblasts remained the same while the ratio synthesized by the endothelial cells varied even though their morphology appeared similar. The fibroblasts synthesized less collagen when grown on collagen-HEMA hydrogels (this effect may be related to age), while the amount of collagen synthesized by the endothelial cells grown on the two surfaces was similar.

Animals↗
PubMed1983

Ultrastructural effects of Clostridium difficile toxin B on smooth muscle cells and fibroblasts.

The mechanism by which Clostridium difficile toxin B causes cells in culture to round was investigated. Cultured human lung fibroblasts and rabbit aortic smooth muscle cells were treated with partially purified or purified toxin B and monitored by light and transmission electron microscopy (TEM). Both preparations caused progressive cell rounding which correlated with disorganization of actin-containing myofilament bundles. Thin myofilaments became fragmented and finally disappeared (after 24 h) and dense bodies became more prominent, while all other organelles appeared unaffected.

Animals↗
PubMed1983

Effect of protein-hydroxyethylmethacrylate hydrogels on cultured endothelial cells.

The use of protein hydroxy ethylmethacrylate (HEMA) hydrogels to control cell morphology and growth, as well as the synthesis of extracellular matrix components, is described in this communication. HEMA hydrogels prepared with collagen support growth of embryonic lung fibroblasts (IMR-90), as well as bovine aortic and pulmonary artery endothelial cells at a level comparable to the respective cells grown on tissue culture surfaces. On the other hand, HEMA hydrogels prepared with solubilized elastin inhibit the fibroblast growth and prevent both types of endothelial cell cultures from achieving their normal morphology. These morphologically altered endothelial cells resume a normal cobblestone-like appearance when subcultivated from the elastin-HEMA hydrogels to tissue culture plastic. When pulsed with [14C]proline, the procollagens synthesized by the endothelial cells on the different surfaces vary, as shown by immunoprecipitation and polyacrylamide gel electrophoresis. On the standard tissue culture plastic, the confluent cells produce mainly type III procollagen in the medium, whereas those endothelial cells grown on collagen and elastin-HEMA hydrogels synthesize primarily type I procollagen (much like sprouting cells on tissue culture plastic), regardless of their morphology.

Acrylates↗
PubMed1983

Preservation of ultrastructure of cells cultured on protein-hydroxyethylmethacrylate hydrogels.

A method for studying the ultrastructure of cells grown on hydroxyethylmethacrylate (HEMA) hydrogels is described. Under normal conditions, HEMA hydrogels tend to swell when placed in hypotonic solutions and to shrink during alcohol dehydration. To overcome this severe swelling and/or shrinking, all solutions used during the fixation procedure are made in Puck's saline G, and dehydration is accomplished with a graded series of ethanol solutions prepared with Puck's saline G and polyethylene glycol. Infiltration of the sample with embedding material is achieved with the aid of a vacuum oven. Our findings suggest that the cells cultured on collagen hydrogels are ultrastructurally indistinguishable from those cultured on tissue-culture plastic. In addition, the unusual crater-like topography of the hydrogel can be utilized as an experimental aid in the study of cell attachment and spreading.

Acrylates↗
PubMed1983

The balance of lung connective tissue elements in elastase-induced emphysema.

Elastase-induced emphysema is associated with changes in all components of connective tissue, including elastin. The abnormal restructuring of lung parenchyma that occurs after elastase administration in hamsters might reflect an abnormal balance of elastin, collagen, and glycosaminoglycan in lung parenchyma. To test this hypothesis, we measured total amounts and levels of accumulation over 24 hr of connective tissue elements in lung explants at several points over a 1-year period after a single elastase treatment in hamsters. We found acute, early changes in the metabolism of elastin, collagen, and glycosaminoglycan consistent with degradation of elastin and increased turnover of collagen and glycosaminoglycan. By day 21 after elastase treatment, lung elastin had returned to control values, then rose and stayed elevated throughout the remainder of the study period. Total collagen levels rose in both control and elastase-treated lungs by the same amount over the year period. However, incorporation of 14C-proline into collagen hydroxyproline was elevated only in elastase-treated lungs over the period of 21 to 360 days. Incorporation of 14C-glucosamine into glycosaminoglycan was greatest over the period of 1 to 5 days after treatment and total levels also peaked at this time. By day 21 both incorporation of glucosamine and total levels of glycosaminoglycan had returned to normal, where they remained. The ratios of glycosaminoglycan to elastin and glycosaminoglycan to collagen were calculated over the period of 21 to 360 days to determine whether the long-term relative balance of these components had changed in elastase-treated lungs. We found that a steady-state imbalance existed between heparan sulfate and collagen and heparan sulfate and elastin, suggesting that an inappropriate amount of heparan sulfate was present relative to the amounts of collagen and elastin. We conclude that administration of elastase results in changes in the long-term balance of lung connective tissue components.

Animals↗
PubMed1982

A method to evaluate the biosynthesis of glycosaminoglycans by the aorta of Cynomolgus monkey.

The biosynthesis of the glycosaminoglycans (GAGs) was investigated in vitro in the aortic tissue of the Cynomolgus monkey incubated with [14C]glucosamine. With the use of a new micromethod, it was possible to quantify the glycosaminoglycans and their radioactive distribution in the aortic tissue and incubation medium. Labeled and nonlabeled chondroitin 6-sulfate, dermatan sulfate, heparan sulfate and hyaluronic acid were measured. Since the sensitivity of this procedure is between 5 and 20 micrograms of GAGs, as little as 5 mg of dry defatted aortic tissue is sufficient for chemical and radioactive analyses.

Animals↗
PubMed1981

Elastin biosynthesis and cross-link formation in rabbit aortic smooth muscle cell cultures.

Rabbit aortic smooth muscle cells in culture produce insoluble elastin which can be purified by treatment with hot alkali. These cells, when maintained in the same flask for long periods of time, continue to accumulate elastin. Both desmosine and isodesmosine, cross-links unique to insoluble elastin, have also been found to increase with time in culture. The results from pulse-chase studies with radiolabeled proline and lysine confirm these observations. All the data indicate that the appearance of the desmosines in the elastin in these cell cultures is a relatively slow process, while the lysine-derived aldehydes appear quite rapidly.

Animals↗
PubMed1981

Lysine-derived cross-links in the egg shell membrane.

Egg shell membrane protein contains significant quantities of the lysine-derived aldehyde, allysine, and its aldol condensation product. NaB3H4 reduction followed by alkaline hydrolysis of purified protein revealed that there were six residues/1000 of both allysine and the reduced aldol while only traces of desmosine and isodesmosine were detected. The amino acid composition of the membrane protein did not resemble that of mammalian elastin.

2-Aminoadipic Acid↗
PubMed1981

Ultrastructural studies of a polygonal myofilament network in cultured rat aortic smooth muscle cells.

Cultured rat aortic smooth muscle cells (SMC) were examined by electron microscopy and found to contain polygonal networks of 75 A degrees thin myofilament bundles. The cells also had large bundles of longitudinally aligned thin myofilaments with periodically spaced dense bodies. Abundant plasmalemmal vesicles were present at the cell periphery, and the cells were connected by desmosomes. Intercellular spaces contained sparse amounts of elastic fibers, a material generally present in SMC cultures. Analyses of amino acids by automated column-chromatography showed that isodesmosine and desmosine, two amino acid residues unique for elastin, were present. Accordingly, it was concluded that polygonal networks, previously detected solely in cultured nonmuscle cells, were present in SMC. Other findings suggest 1) a change in myofilament arrangement takes place during cell migration, and 2) rat aortic SMC grown in tissue culture flasks is an important experimental tool in the study of cell motility since such myofilament rearrangements were observed to occur up to fourteen days in first passage.

Animals↗
PubMed1980

Synthesis of glycosaminoglycans by cultured rabbit smooth muscle cells.

Rabbit aortic smooth muscle cells were evaluated for their ability to synthesize and accumulate glycosaminoglycans (GAGs). Because of the sensitivity of the microtechniques utilized, it is possible to determine the specific radioactivity of the GAGs obtained after radioactive incorporation of [35S]SO4(2-) and [14C]glucosamine. Data obtained at various incubation times indicate that the distribution of the GAGs secreted by the cells into the medium is different from that retained by the cell layer. Hyaluronic acid was shown to be the most abundantly produced GAG, and much of this GAG does not appear to be incorporated into the extracellular matrix. Also, a high percentage of the total chondroitin sulfate B synthesized was secreted into the medium. On the other hand, most of the heparan sulfate and chondroitin sulfate C/A synthesized seems to be associated with the cell layer. These results are consistent with those found in whole rabbit aorta.

Animals↗
PubMed1980

Use of collagen-hydroxyethylmethacrylate hydrogels for cell growth.

Collagen-hydroxyethylmethacrylate hydrogels were prepared by polymerizing monomeric hydroxyethylmethacrylate in the presence of various concentrations of soluble native collagen. The resulting transparent hydrogels were evaluated as substrata for growth of IMR-90 human embryonic lung fibroblasts. Without collagen no significant growth occurred, whereas a dose-response curve expressing maximal cell growth against collagen concentration could be constructed quite readily by the use of appropriate hydrogels. The method allows for quantification of the collagen contribution to cell growth and, in a more general sense, provides the foundation for a relatively easy procedure to probe mechanisms of cell adhesion and cell differentiation.

Acrylic Resins↗
PubMed1979

Collagen synthesis in normal BHK cells and temperature-sensitive chemically transformed BHK cells.

Collagen synthesis in normal BHK 21/cl 13 and chemically transformed temperature sensitive BHK 21/cl 13 cells (Me2N4) was assessed by examination of hydroxyproline formation and collagenase-susceptible protein. The Me2N4 cells lost their ability to synthesize collagen at both permissive and nonpermissive temperatures for transformation. These conclusions were confirmed by polyacrylamide-gel eletrophoresis and CM-cellulose chromatography. Prolyl hydroxylase activity was present in both normal and transformed cells even when no collagen could be demonstrated. The production of noncollagen protein, although decreased in the transformed cell, did not change as drastically as the collagen synthesis.

Animals↗