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Biomedical subjects

S Shoshan

Publications and source records attributed to S Shoshan.

At least 37 records · Page 2Linked to original sources
PubMed1990

Prolonged systemic administration of cyclosporin A affects gingival epithelium.

Gingival biopsies were obtained from 12 patients suffering from Behcet's disease who were treated with Cyclosporin A (CsA) for up to 20 months. Preparations were made for examination with both light and scanning electron microscopy (SEM). Along with known changes in the gingival epithelial structure observed following CsA treatment, we also found unusual clusters of needle-like crystallites embedded in the epithelium, mostly at the base of the acanthotic projections. Toluidin blue staining revealed increased numbers of both intact and degranulated mast cells in the attached epithelium. It is concluded that CsA affects the gingival epithelium and that the clinically observed enlargement of gingival tissue following prolonged treatment with CsA is due primarily to CsA-epithelial interaction.

Behcet Syndrome↗
PubMed1988

The effect of cyclosporin A (CsA) treatment on gingival tissue of patients with Behçet's disease.

Gingival biopsies were obtained at various intervals for a period of two years from 12 patients suffering from Behçet's disease who were under a clinical trial of cyclosporin A (CsA) treatment. The levels of nondialyzable hydroxyproline (Hypro) were determined in the medium of the cultured tissues. Histologic examinations were also performed every three months. Correlations between the CsA blood levels and the levels of nondialyzable Hypro indicated a reciprocal relationship, especially at blood levels of CsA higher than 600 ng/ml. Histologic examination of gingival sections from CsA-treated patients showed swelling of the epithelial cells, formation of perinuclear clear zones, widening of intercellular gaps and formation of several basal cell layers. In addition, foci of PAS-positive material were found in both the epithelium and stroma. It is assumed that the gingival enlargement observed in the CsA-treated patients was not due to an increase in tissue collagen but rather to an increase in epithelium combined with an accumulation of noncollagenous extracellular matrix material.

Behcet Syndrome↗
PubMed1988

A novel method to study directed cell migration in culture.

Directional migration of gingival fibroblasts was elicited in a cell culture system using reconstituted type I collagen fibers as a source of the putative chemoattractant. The rate of migration was expressed as Migration Index which turned out to be dependent on and directly related to the distance between the cells and the collagen. It is believed that this method enables one to study many different phenomena associated with extracellular matrix and cell interactions.

Animals↗
PubMed1987

Decreased adhesion formation in flexor tendons by topical application of enriched collagen solution--a histological study.

In order to improve gliding function of damaged flexor tendons in chickens, we topically applied enriched collagen solution (ECS) to the tendon sheaths of severed tendons. Previous studies using the same experimental model showed improvement of gliding function in the damaged tendons biomechanically and increased collagenolytic activity in the area of the damage after application of ECS. In the present study we evaluated the influence of ECS on peritendinous adhesion formation and on the healing process of the tendons histologically. We found that topically applied ECS reduced adhesion formation, mostly during the first week, without adversely affecting tendon healing or scar maturation.

Administration, Topical↗
PubMed1987

Re-attachment of periodontal ligament by collagen in experimentally-induced alveolar bone dehiscence in dogs.

Fifty-four bone dehiscences were made in nine dogs by reflecting mucoperiosteal flaps on the labial aspect of lower and upper incisors and premolars and removing alveolar bone. One half of the dehiscences were treated with native enriched collagen solution (ECS) prepared from acid-soluble dog-skin collagen. Six weeks later, histologic sections were prepared from both the ECS-treated and untreated control sites. Re-attachment was promoted by the ECS preparation; there was arrest of epithelial migration apically and formation of new bone and cementum, as well as proliferation of fibrous connective tissue that became attached to the newly-formed cementum. This effect could be due to an influence of ECS on the chemotaxis of connective-tissue cells and to an anti-migratory (barrier) effect on gingival epithelium.

Alveolar Process↗
PubMed1986

Capsule around silicone implants in diabetic rats: histological and biochemical study.

Polydimethylsiloxane (silicone) implants were subcutaneously placed in the back of diabetic and normal rats. After three months the rats were killed and the fibrous capsule around the implants was histologically and biochemically examined. A significant quantitative difference (p less than 0.001) was found in the thickness of the capsules, which were two to three times thicker in the diabetic animals. The biochemistry showed an increase of neutral salt-soluble collagen in the diabetic group; electrophoresis revealed only type I collagen in the diabetic and type I and III in the normal rats. From this experimental trial it seems that diabetes mellitus is another factor in formation of a thick capsule around silicone implants.

Animals↗
PubMed1985

Increased collagenolytic activity in severed and sutured tendons following topical application of exogenous collagen in chickens.

To verify the role of collagenase in reduction of peritendinous adhesion by topical application of exogenous collagen, the flexor tendons of 30 chickens were severed and sutured. Exogenous, native enriched collagen solution (ECS) was introduced in the tendon sheath via a polyethylene catheter. The effect of ECS on collagenolytic activity in the healing tendon was assessed 1, 2, and 3 weeks later both by determining the relative amounts of dialyzable protein and hydroxyproline and by using the collagen film collagenase assay. The results obtained indicated a significant increase in both dialyzable hydroxyproline level and collagenolytic activity in the ECS-treated tendons as compared with the untreated controls. It is suggested that the effect of the topically applied exogenous collagen on increasing the collagenolytic activity may be directly related to previously observed increased gliding capacity of the tendons in the same experimental model.

Animals↗
PubMed1985

Cessation of epithelial cell movement at native type I collagen-epithelial interface in vitro.

Two foci of gingival epithelial cells from the dog were grown in culture in dishes which were coated with gingival epithelial extracellular matrix (GEEM). A streak of native, reconstituted type I collagen fibers had been placed at the midline of the dish between the two foci. The epithelial cells spread and proliferated in all directions, but their motility ceased at the collagen-epithelial interface, where they piled up and formed several layers. It is concluded that type I collagen may serve as a biological barrier to stop undesirable epithelial cell movement in vivo.

Animals↗
PubMed1984

Restoration of periodontal attachment employing enriched collagen solution in the dog.

Three wall intrabony defects were produced in 11 dogs using a round bur followed by curettes and hoes. A copper band was fixed to the tooth with stainless steel ligature wire. Six weeks later, the copper band was removed and the defect was treated with an enriched collagen solution (ECS) prepared from acid-extracted dog skin collagen. Thirty-three defects were treated with ECS and 33 defects were controls. Healing was assessed histologically 4 and 6 weeks after treatment for the presence of new cementum, periodontal ligament and alveolar bone, as well as arrested epithelial downgrowth along the dental root. Unlike the controls, treatment with ECS resulted in restoration of periodontal attachment after 4 weeks. This included formation of new cementum, new alveolar bone and dense connective tissue fiber running between bone and cementum. Control sections showed epithelial migration along the root, separating it from the adjacent connective tissue and thus preventing new attachment.

Alveolar Process↗
PubMed1984

In vitro incorporation of proline into keratoconic human corneas.

Corneal buttons were obtained from four young adults with advanced keratoconus following perforating keratoplasty. The corneal buttons were incubated in organ culture media containing 3H-proline. Autoradiographs of corneal sections showed that the incorporation of the radioisotope was significantly higher in all layers of the kerotoconic corneas than that found in the normal controls, indicating an increased protein biosynthesis in the former. It is suggested that in spite of the found increased synthetic activity, slow destruction and thinning of the cornea in keratoconus might occur as the result of inadequate compensation for tissue loss due to increased collagenolytic activity in the disease.

Adult↗
PubMed1983

Cellular sensitivity to collagen in thromboangiitis obliterans.

We studied 39 patients with thromboangiitis obliterans to determine their cellular and humoral immune responses to native human collagen Type I and Type III, which are constituents of blood vessels. Cell-mediated sensitivity to these collagens was measured by an antigen-sensitive thymidine-incorporation assay. The mean stimulation index--the ratio of thymidine incorporation in the presence of antigen to that in its absence--with both Type I and Type III collagens used as antigens was significantly higher in patients with thromboangiitis obliterans than in patients with arteriosclerosis obliterans or in healthy male controls. Lymphocytes from 77 per cent of the patients with thromboangiitis obliterans exhibited cellular sensitivity to human Type I or Type III collagens (or both). Furthermore, in 17 of 39 serum samples from the patients with thromboangiitis obliterans a low but significant level of anticollagen antibody activity was detected, whereas there was no antibody activity in serum samples from controls. These results suggest that there is a distinct etiologic factor in this disease and also raise the possibility of differentiating between thromboangiitis obliterans and arteriosclerosis obliterans by immunologic means.

Adult↗
PubMed1983

Demonstration of collagenase activity in adult Strongyloides ratti (Nematoda:Strongyloididae) and its absence in the infective larvae.

Larvae and adults of Strongyloides ratti were examined for collagenolytic activity on 14C proline-labelled, native, guinea-pig skin collagen substrate. The activity was measured by determining either the amount of hydroxyproline released or the amount of radioactivity in the solubilized fraction of the collagen substrate. Bacterial collagenase was used for enzyme control and trypsin served as substrate control. No collagenolytic activity was found in living larvae, their extracts or metabolites. The collagenolytic activity of the metabolites of adult worms appeared weak, whereas that of the extracts of the adults was pronounced. It is suggested that collagenase is active in the adult females at the time of migration in the intestinal mucosa during oviposition.

Animals↗
PubMed1983

Electroconductivity of bone in vitro and in vivo.

In view of conflicting data in the literature regarding the electroconductivity of bone, measurements were performed both in vivo and in vitro by using alternating current of 100.0 mA and 1.0 mA at a frequency of 1000 cycles/second and the four-electrode method. Electrodes were inserted through all of the bone layers into the bone marrow space of the femora of seven rabbits. Bone electric resistance was measured also in situ 30 minutes after the death of the animals. A threefold increase in resistance of bone, from about 600 to about 1700 ohm, occurred in situ 30 minutes after the death of the animals, and an enormous resistance, about 10(10) ohm, was measured in vitro. It was also apparent that femora from the different rabbits had different values of electric resistance both in vivo and in vitro. If electroconductivity of bone is determined by body fluids rather than by the bone tissue per se, measuring the "specific resistance" of bone in vivo is meaningless.

Animals↗
PubMed1983

The effect of prolonged phenytoin administration on non-collagenous components of gingival tissue.

The hyperplastic gingivae of 11 epileptic patients on prolonged phenytoin therapy and those of control patients were excised during routine periodontal surgery. The tissues were homogenized and the hexosamine, uronic acid and total protein contents were determined. It was found that the gingivae of patients on prolonged phenytoin therapy had significantly raised hexosamine, uronic acid and total protein levels as compared with the controls. However, the relative concentration of the three parameters was similar in both groups. It is suggested that the enlargement of gingival tissue observed in patients who "respond" to prolonged phenytoin treatment may be the result not only of collagen over-production but also of the elevated levels of GAG.

Adult↗
PubMed1982

One-year follow up for the use of collagen for biological anchoring of acrylic dental roots in the dog.

Second premolars in both upper and lower jaws of 6 dogs were extracted and acrylic resin replicas were made of the roots. Horizontal channels were drilled across the root replica perpendicular to the long axis. Before implantation, the prepared root replicas were immersed in a solution of native collagen. One year after implantation, proliferation of connective tissue and newly-formed viable bone were observed within the channel as well as surrounding the treated implants. All control implants without collagen treatment were rejected leaving chronically inflamed implantation sites.

Acrylic Resins↗
PubMed1982

Collagen metabolism and phenotype after prostaglandin E2 treatment of granuloma: direct and macrophage-modulated effects.

Local administration of PGE2 (2 micrograms) to polyether sponges, implanted s.c. in rats, inhibited hydroxyproline and total protein accumulation, without altering relative amounts of collagen, when administered early during granuloma development. In contrast, while DNA as well as total protein accumulation was inhibited by local PGE2 treatment of established granuloma, hydroxyproline accumulation and the relative amounts of collagen were enhanced. This PGE2-induced collagen enhancement was associated with an increased type III : type I collagen ratio, possibly due to differential intracellular breakdown of newly synthesized collagen. The solubility of granuloma collagen was unaffected by PGE2. Impregnation of sponges with carrageenan before implantation, thereby giving macrophage-dominated granuloma, did not affect the changes in protein and DNA induced by later treatment with PGE2, but did reverse the PGE2-induced accumulation of hydroxyproline. This latter effect probably reflects macrophage-mediated, PGE2 enhancement of collagenolytic activity.

Animals↗
PubMed1982

Collagenolytic activity in keratoconus.

Corneal buttons were obtained from eight young adult patients with advanced keratoconus and were incubated in an organ culture system. The medium was assayed for collagenolytic activity using 14C-labeled reconstituted native collagen fibers as substrate. The assay was performed with and without prior collagenase activation with trypsin. The results indicated that the medium obtained from keratoconic corneas showed higher levels of collagenolytic activity compared with normal control corneas. We suggest that the level of collagenase activation may be a pathogenic factor in the development of keratoconus.

Adult↗