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Biomedical subjects

S C Fisher

Publications and source records attributed to S C Fisher.

7 recordsLinked to original sources
PubMed2001

Myospherulosis complicating cortical block grafting: a case report.

BACKGROUND: Myospherulosis of the oral cavity is an inflammatory, granulomatous lesion historically associated with the use of petrolatum-based antibiotic ointment placed in third molar extraction sites to prevent postoperative infection. METHODS: A case of bilateral myospherulosis is presented, in which large lesions complicated the procurement of a cortical block graft used to prepare a mandibular molar edentulous space for implant placement. By obtaining the block graft from a more lateral location on the mandible, an adequate graft was procured and was successfully grafted into an atrophic edentulous ridge. RESULTS: The cortical block graft was successfully incorporated by the recipient site, which received a wide-body, threaded dental implant 6 months later. Healing was uncomplicated, and a functional implant-supported restoration was successfully achieved. CONCLUSIONS: Myospherulosis, though rare today, may present a significant obstacle to the procurement of cortical block grafts. In this case, thorough debridement of the material resulted in subsequent healing of the myospherulosis defect, but prevented procurement of the cortical graft from the planned site. The dimension and volume of the neighboring cortical bone were adequate, and the augmented edentulous space was subsequently restored with a functional endosseous implant. The success seen in these 2 sites would seem to confirm the assumption that size and location of myospherulosis defects are critical factors in obtaining a successful clinical result in implant patients.

Adult↗
PubMed1988

Polyphosphoinositide hydrolysis in response to light stimulation of rat and chick retina and retinal rod outer segments.

Phosphoinositides of chick and rat retina were labelled with [3H]inositol. Exposure of retinal preparations to light for 30 s caused loss of labelled phosphatidylinositol 4,5-bisphosphate and to a smaller extent of the other phosphoinositides. Similar light-induced changes were seen when rod outer segment preparations were used and, when these were illuminated in calcium-free media, phosphatidylinositol 4,5-bisphosphate was the only lipid affected. No inositol 1,4,5-trisphosphate was seen after either 30 s or 5 s of illumination of retina or 30 s illumination of rod outer segments. It is concluded that this compound plays no direct part in vertebrate photoreceptor light transduction, though phosphoinositide metabolism might relate to adaptation mechanisms.

Animals↗
PubMed1988

Interactions of triiodothyronine, insulin and dexamethasone on the binding of human LDL to rat hepatocytes in monolayer culture.

Rat hepatocytes were maintained for the first 24 h in culture in the presence of 10% (v/v) newborn calf serum and then for a further 16 h in serum-free medium containing 2 g bovine serum albumin per litre. The presence of 1-100 nM triiodothyronine (T3) in the second incubation significantly increased binding of human 125I-LDL to the LDL receptor. Unlike insulin, T3 was unable to reverse the decrease in binding brought about by dexamethasone. The increased binding to the LDL receptor produced by insulin and T3 was additive. We conclude that T3, insulin and glucocorticoids may play important roles in regulating plasma LDL concentrations by direct effect on LDL uptake by the liver.

Animals↗
PubMed1987

Effects of preincubation of primary monolayer cultures of rat hepatocytes with low- and high-density lipoproteins on the subsequent binding and metabolism of human low-density lipoprotein.

1. There are two distinct binding sites (Site 1 and Site 2) for human low-density lipoprotein (LDL) on rat hepatocytes in monolayer culture [Salter, Saxton & Brindley (1986) Biochem. J. 240, 549-557]. 2. Binding of 125I-LDL to Site 1, but not to Site 2, is up-regulated between 20 and 44 h in culture by preincubation of the cells with human high-density lipoprotein 3 (HDL3). 3. A similar preincubation with HDL2 had no significant effect on binding to either site. 4. Preincubation with human LDL led to a partial down-regulation of subsequent binding of 125I-LDL to Site 1. Since binding after incubation with LDL was measured at 37 degrees C, binding to Site 2 could not be distinguished from LDL that had been internalized by the cells. 5. Hepatocytes were shown to degrade 125I-LDL, resulting in the accumulation of [125I]iodotyrosine in the medium. Evidence was found that iodotyrosine may be further degraded by deiodinase produced by the cells. 6. Regulation of binding to Site 1 by preincubation with LDL or HDL3 was found to lead to a parallel regulation of LDL degradation. 7. It is concluded that rat hepatocytes not only bind but also metabolize human LDL and that these processes are under metabolic regulation.

Animals↗
PubMed1987

Binding of low-density lipoprotein to monolayer cultures of rat hepatocytes is increased by insulin and decreased by dexamethasone.

Rat hepatocytes were maintained in monolayer culture for 20 h in the presence of 10% (v/v) newborn calf serum and then for a further 1-24 h in serum-free medium containing 2 g bovine serum albumin/l. The specific binding of human 125I-LDL to two distinct sites was then measured at 4 degrees C. Binding to site 1 was displaced by dextran sulphate while that to site 2 was not. The presence of 1-100 nM insulin for 24 h in the second incubation significantly increased binding to site 1. Significant increases were also seen when cells were incubated with 10 nM insulin for 1 h. No significant effects of insulin on binding to site 2 were observed. In contrast, 10 nM-1 microM dexamethasone decreased binding to both sites. The effects of these hormones were mutually antagonistic.

Animals↗