PubMed Health⌕ Search

Biomedical subjects

S R Gordon

Publications and source records attributed to S R Gordon.

At least 37 records · Page 2Linked to original sources
PubMed1989

Ultrastructural immunocytochemical localization of fibronectin deposition during corneal endothelial wound repair. Evidence for cytoskeletal involvement.

The distribution of the extracellular matrix (ECM) protein, fibronectin (FN), has been examined ultrastructurally in noninjured and injured rat corneal endothelium in vivo and in vitro by immunoperoxidase cytochemistry. In noninjured endothelia, FN was observed within the rough endoplasmic reticulum (RER) cisternae but not along the cell-Descemet's membrane (DM) interface. Twenty-four and 48 h after a circular freeze injury, immunoperoxidase reaction product was detected at the cell-DM interface as well as within cytoplasmic vesicles and intercellular spaces. By 1 and 2 wk post-injury, a line of reaction product could still be demonstrated at the cell-DM interface and evidence for newly deposited basement membrane material was observed in this region. In order to understand whether fibronectin deposition during wound repair was dependent on cytoskeletal influences, organ culture experiments were performed in which the media was supplemented with either 10(-8) M colchicine or 2.5 X 10(-3) M cytochalasin B. Without inhibitors, injured corneas cultured for 24 h had FN deposition at the cell-DM interface similar to the in vivo results. Corneas cultured in the presence of cytochalasin B also showed FN deposition at the cell-DM interface. However, when injured endothelia were cultured in the presence of colchicine, no reaction product was observed at the cell-DM interface, although it could be detected intracellularly within RER. Incubating the tissues in the presence of puromycin abolished all extracellular and intracellular staining. These results indicate that during wound repair, corneal endothelial cells produce fibronectin and deposit it upon Descemet's membrane by a mechanism that may be mediated by microtubules.

Animals↗
PubMed1988

Patient satisfaction with current dental condition related to self-concept and dental status.

Structured interviews were administered to 168 male veterans from five locations to examine the relationship between attitudes toward dental esthetics, age, self-concept, and dental status. Results indicate the following. 1. Subjects who had a more positive self-concept rated their current dental condition higher. 2. Veterans who use dentures do not have a lower self-concept than those who have remaining natural teeth and feel more positively about their dental appearance. 3. Among the sample studied, dental appearance was considered less important than function or comfort. 4. Diminished self-concept is not associated with greater concern for dental esthetics.

Adult↗
PubMed1988

Changes in distribution of extracellular matrix proteins during wound repair in corneal endothelium.

The distribution of fibronectin (FN) and laminin (LM) in non-injured and injured rat corneal endothelium in vivo was investigated by light microscopy using immunoperoxidase cytochemistry. In non-injured tissues, both FN and LM have distinct pericellular staining patterns and exhibit some diffuse cytoplasmic staining. After a circular freeze injury, cells migrating into the wound area at 24 hr lack the characteristic pericellular staining observed in non-injured cells but show cytoplasmic staining for both extracellular matrix glycoproteins. Endothelial cells on the periphery of such preparations do not partake in wound repair and retain their pericellular staining patterns. Forty-eight hours after injury, cells have filled in the wound area but are disorganized. They display intracellular FN and LM staining but do not demonstrate any pericellular staining. When observed 10 days after injury, a uniform monolayer has formed but neither FN nor LM is detected pericellularly. By 14 days post injury, endothelial cells in the wound area display pericellular FN patterns but not LM patterns. This may reflect differences in the function of each glycoprotein in maintaining the attachment of the endothelium to Descemet's membrane.

Animals↗
PubMed1988

Use of selected excitation filters for enhancement of diaminobenzidine photomicroscopy.

Enhancement of the diaminobenzidine (DAB) reaction product for light photomicroscopy was investigated using commercially available glass interference filters FITC-495, BG38, and BG12. The oxidized DAB transmission curve between 400-700 nm revealed a broad peak extending mostly through the yellow to red portions of the visible light spectrum, indicating that no single color predominates. Absorption spectra from the interference filters showed that FITC-495 gave total absorbance from 495-650 nm, with a smaller peak at 675 nm; BG38 transmitted at least a percentage of every wavelength up to 700 nm, whereas BG12 absorbed all light above 490 nm. To determine whether these filters could photographically increase DAB reaction product contrast, photographs were taken of corneal endothelial cells 24 hr after freeze injury. At this time, these cells demonstrate increased levels of laminin, as revealed by immunoperoxidase cytochemistry. When photography was performed using either no filter or a standard green filter, DAB contrast relative to background was minimal. However, when photographs were made using either the FITC-495 or the BG12 filter, DAB contrast increased sharply, although background density increased in the former case and decreased greatly in the latter. BG38 by itself did not increase DAB contrast. However, when used in combination with FITC-495 good DAB contrast was achieved and background density was lower than that seen using FITC-495 alone. Therefore, selective interference filters can photographically increase DAB contrast for studies using immunoperoxidase cytochemistry.

3,3'-Diaminobenzidine↗
PubMed1987

Investigations on circumferential microfilament bundles in rat retinal pigment epithelium.

The presence of contractile proteins in normal rat retinal pigment epithelium has been studied using fluorescence and electron microscopy. Investigations using the F-actin binding toxin, phallacidin, coupled to the fluorochrome nitrobenzoxadiazole, revealed a band of fluorescence at or near the cell membrane. Immunofluorescent observations with anti-myosin and anti-alpha-actinin antisera gave similar results. Electron microscopy employing glutaraldehyde-8% tannic acid fixation revealed the presence of a circumferential microfilament band beneath the pigment epithelial apical surface that is closely associated with the plasma membrane and junctional complexes. Freeze-fracture studies confirmed the relationship of this band to the junctional complexes. The microfilament band measures approximately 0.5 micron +/- 0.2 micron in width and is composed of numerous 6 to 7 nm filaments. Some microtubules are seen in regions around the band, but no organelles appear to be associated with this structure. In en face sections through the zonula adherens, the circumferential microfilament band is associated with 30-nm electron-dense particles that are bound to the internal side of the membrane. Morphological evidence suggests that these may serve in anchoring the band to the membrane and assist in aligning the microfilament bands of adjoining cells. In the subapical cytoplasm, a microfilament bundle network was detected that interfaced with the circumferential microfilament band. In some cases, pigment epithelium was incubated in media-199 containing 25 to 50 ng/ml phallacidin prior to fixation. Circumferential microfilament bands of tissues treated in this manner exhibited a striated appearance.

Actin Cytoskeleton↗
PubMed1987

Treatment planning in dental schools.

Treatment planning is a complex process that is difficult to teach and evaluate. Various frameworks have been used to organize the decision-making process. While many have merit, the transition from ideal to realistic plan is rarely described in detail adequate for teaching purposes. None of the research recommends an objective method to measure students' treatment planning skills. A treatment planning model is described that would follow presentation of the "ideal" treatment plan in the curriculum. The model focuses specifically on the sequence of decisions necessary to formulate appropriate treatment plans for adult dental patients who present with compromising factors. Also, a method is suggested for objective evaluation of dental students' mastery of dental treatment planning at each of several intermediate steps, as well as at the final result.

Curriculum↗
PubMed1986

Actin, myosin, and laminin localization in retinal vessels of the rat.

Actin, myosin, and laminin have been localized in retinal vessels of normal rats by fluorescence microscopy. Actin was localized with the fluorescent F-actin binding toxin nitrobenzoxadiazole phallacidin (NBD-Ph). Indirect immunofluorescence was used to localize myosin and laminin. In addition, laminin localization was also performed with the Protein A-horseradish peroxidase (PA-HRP) method. NBD-Ph staining gave strong fluorescence in both retinal capillaries and larger vessels. Anti-myosin fluorescence could also be observed in trypsin digests of the retinal vasculature. Strong fluorescence of PA-HRP reaction product could be detected in the walls of vessels exposed to anti-laminin antibody. Actin distribution in vessels of the RCS rat with inherited retinal degeneration (retinal dystrophic RCS rat) was also studied. After exposure to NBD-Ph, all capillaries showed fluorescence. However, it was more intense in many of the capillaries in the outer retina, which also appeared morphologically abnormal. Electron microscopy of retinal capillaries fixed in 2.5% glutaraldehyde containing 8% tannic acid revealed numerous microfilaments in the pericyte cytoplasm and some in the basal portion of endothelial cells. In pericytes, these microfilaments are in close association with the endothelial side of the cell. Tangential sections through this region indicate that these filaments may be anchored to the membrane at this site.

Actins↗
PubMed1986

Oral assessment of the dentulous elderly patient.

The percentage of elderly persons retaining natural teeth is increasing. Although many of these individuals cannot be convinced to see a dentist regularly, they are generally seen by a physician or nurse relatively frequently. The physician or nurse can provide a vital service for these patients by performing oral screening examinations. A technique is described for accomplishing this.

Aged↗
PubMed1985

Plasma membrane-associated vesicles in retinal capillaries of the rat.

The structure and function of abluminal vesicles in endothelial cells of rat retinal capillaries was examined using glutaraldehyde-tannic acid fixation and the hemeproteins--horseradish peroxidase, microperoxidase, and lactoperoxidase--as tracers. Numerous vesicles, delimited by a tannic acid-positive membrane, were distributed along the abluminal front. Other vesicles were arranged in clusters and chains or tubule-like structures. Such vesicles were not found in the vicinity of the capillary lumen. When the retina was exposed to hemeproteins, either in vitro or after intravitreal injection, the abluminal vesicles became labeled with tracer reaction product. Apparently "free" vesicles and tubules seen in tangential sections through the basal lamina were also labeled, suggesting that they were in continuity with the plasma membrane in another plane of section. No enzyme reaction product was present in the capillary lumen. Peroxidase-positive multivesicular bodies were observed, suggesting that some protein was endocytosed and directed to lysosomes where it was presumably degraded. The results suggest that abluminal endothelial vesicles represent pits or invaginations of the plasma membrane and, as such, are not involved in the transendothelial transport of protein from the perivascular space to the capillary lumen. Tannic acid treatment revealed a population of similar vesicles associated with the plasma membrane of pericytes. After exposure to hemeproteins, enzyme reaction product was localized in these vesicles and in a few multivesicular bodies. The results suggest that the majority of these vesicles are in continuity with the plasma membrane and are not involved in endocytosis.

Animals↗
PubMed1985

Effect of hyperosmolar medium on the protein synthesis and morphology of epithelial cells of the cultured rabbit lens.

The effects of hyperosmolar medium on the lens epithelial cell protein synthesis and morphology were studied. It was found that the hyperosmolar medium inhibits protein synthesis, and the high molecular weight proteins were more susceptible to the osmolar shock than were the low molecular weight proteins. Fine structure analysis of the epithelial cells of the lenses incubated in hyperosmolar medium showed that the osmolar shock caused a reduction in the amount of rough endoplasmic reticulum and polysomes; some chromosome clumping was also evident. Whether the morphological changes observed were directly related to the decrease in the rate of protein synthesis is not clear.

Animals↗