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Biomedical subjects

S Belcastro

Publications and source records attributed to S Belcastro.

At least 19 recordsLinked to original sources
PubMed2002

Biomembranes enriched with TGFbeta1 favor bone matrix protein expression by human osteoblasts in vitro.

The use of growth factors in oral tissue regeneration is currently under investigation. When growth factors are combined with commercial materials, the in vitro mechanisms of action still remain unclear. The present study first evaluated the capacity of barrier membranes, used in oral surgery, to sequester TGFbeta(1). Resorbable HYAFF, paroguide, poly DL-lactide and nonresorbable PTFE membranes were immersed in MEM containing 0.2 ng (125)I-TGFbeta(1) for different periods of time. It was found that HYAFF membrane and paroguide sequestered the most TGFbeta(1), which was then released in its active form (as shown by the CCL64 cell line bioassay). Untreated membranes and membranes enriched with TGFbeta(1) were then used as substrate for human bone cells to evaluate the synthesis of the osteoblast phenotype, as indicated by specific parameters. Results showed that membranes enriched with TGFbeta(1) increased alkaline phosphatase activity, collagen, and osteocalcin production more than untreated membranes. HYAFF and paroguide membranes, which sequestered the most of TGFbeta(1), were the most suitable for stimulating bone matrix proteins.

Absorbable Implants↗
PubMed2001

In vitro comparison of bioabsorbable and non-resorbable membranes in bone regeneration.

BACKGROUND: Barrier membranes are used to prevent down-growth of the oral mucosa along the root surface and to allow alveolar bone regeneration in guided tissue regeneration. Several studies have demonstrated bone regenerates in the presence of bioabsorbable and non-resorbable membranes, but no studies have compared multiple bioabsorbable barriers to one another and to non-resorbable barriers. This study evaluated the in vitro influence of bioabsorbable and non-resorbable membranes on specific parameters of human osteoblast activity. METHODS: Human osteoblasts were cultured on bioabsorbable membranes made of collagen, hyaluronic acid, and poly DL-lactide, and the most common non-resorbable membrane which is made of expanded polytetrafluoroethylene (ePTFE). The osteoblasts were cultured in vitro for 24 hours on barrier membranes in the presence of 3H-thymidine and 3H-proline to study cell proliferation and collagen synthesis. Transforming growth factor-beta1 (TGF-beta1) secretion was evaluated in conditioned media using an ELISA kit. RESULTS: The results showed that collagen and poly DL-lactide stimulated DNA synthesis more than ePTFE and hyaluronic acid. All bioabsorbable membranes significantly increased collagen synthesis and alkaline phosphatase activity. Collagen and hyaluronic acid increased secretion of TGF-beta1, a growth factor involved in bone remodeling. CONCLUSIONS: These data suggest bioabsorbable membranes, particularly collagen and hyaluronic acid, may promote bone regeneration through their activity on osteoblasts.

Absorbable Implants↗
PubMed2000

Biocompatibility of alloys used in orthodontics evaluated by cell culture tests.

The cytotoxicity of the most common alloys used in orthodontic appliances was determined by cell culture testing. Human gingival fibroblasts were cultured on 304 and 316 stainless steel, on brazing alloy composed of palladium (Pd), copper (Cu), and silver (Ag), and on plastic substrate (control). Studies were carried out with SEM and radiolabeled precursor incorporation. Cells were cultured in MEM without serum but with the addition of (3)H-thymidine to evaluate cell proliferation and (3)H-glucosamine to evaluate glycosaminoglycan (GAG) synthesis and secretion in the culture medium. Moreover, gingival fibroblasts were cultured in the presence of some metal ions generally released by orthodontic appliances to evaluate the cytotoxic effects of single ions. Morphologic observations with SEM and radiolabeled incorporation studies showed that 304 and 316 stainless steel were more biocompatible than the brazing alloy. Among the metal ions tested, Ag and Pd, constituents of the brazing alloy, showed the highest cytotoxicity.

Alloys↗
PubMed2000

In vitro cytotoxic effects of orthodontic appliances.

The objective of this study was to evaluate the effects of an orthodontic appliance and of its components (brackets, bands, and arch wires) on some cell functions. Fibroblasts were cultured either in the presence of one unwashed orthodontic appliance, or one orthodontic appliance immersed in MEM for 28 days before use (washed appliance), or in the presence of MEM in which the appliances had been immersed. At the end of in vitro maintenance, morphological studies were carried out with SEM and TEM. Cell proliferation and GAG synthesis and secretion by radio-labeled precursors were assessed. The data indicated that unwashed appliances were more cytotoxic than washed ones. Moreover, the arch wire was the most biocompatible component of the orthodontic appliance, and the bracket was the least biocompatible. A comparative study into the effects on cell proliferation of the most common metal ions released by the appliances was also carried out. At the concentration released by one orthodontic appliance immersed for 28 days, the highest reduction in DNA synthesis was observed in the presence of Cu(++).

Adult↗
PubMed1999

Ion release from orthodontic appliances.

OBJECTIVE: The microbiological and enzymatic characteristics of the oral cavity would seem to provide a suitable environment for the corrosion of metals. We assayed the release of metal ions from one orthodontic appliance which included two 304 and 316 steel molar bands, ten 316 steel brackets, one nickel-titanium archwire and a brazing alloy to connect the elements of molar bands and brackets. METHODS: The orthodontic appliance was dipped in both inorganic (pH 3.5-6.5) and organic acid solutions (w/v 1% each of tartaric, citric and ascorbic acid at pH 2.2 or 1.5% each of lactic and acetic acid at pH 2.5). The release of nickel (Ni), chromium (Cr), copper (Cu), silver (Ag) and palladium (Pd) was determined using an atomic absorption spectrophotometer Varian AA 10. RESULTS: The release of Ni, Cr and Cu was markedly less at pH 6.5 than at pH 3.5 at all time points in acid solution. Daily release/single appliance after the first day decreased. Contrary to expectations, appliances immersed in organic acid solutions at pH 2.2 or 2.5 after 28 days generally released an amount of ions similar to that observed in inorganic acid solution at pH 3.5, with the exception of Cu. Release of silver and palladium, two metals present in the brazing alloy, proved to be very low (approximately 0.2 microgram after 28 days). CONCLUSIONS: The daily release of Ni, Cu and Cr by an orthodontic appliance in acid pH, particularly favourable to corrosion, was well below that ingested with a normal daily diet. It is therefore concluded that the quantities of metal ions released in our experimental conditions should not be cause for concern in utilising the appliance.

Chromium↗
PubMed1997

Phenotype expression of human bone cells cultured on implant substrates.

Bone cells derived from the human jaw were cultured on titanium, titanium coated with hydroxyapatite (THA) or with plasma spray (TPS) to study the behaviour of the cells anchored to implant substrates. Bone cells were cultured in MEM with the addition of [3H]-thymidine to evaluate cellular proliferation, and [3H]-glucosamine to evaluate GAG synthesis and accumulation in the extra-cellular matrix (ECM). Moreover, to study the degradation of GAG bone cells were cultured in the presence of NH4Cl, an amine known to inhibit lysosomal activity. Our results show that TPS is the substrate that favours both cellular proliferation and the accumulation of GAG in the ECM.

Ammonium Chloride↗
PubMed1997

Phenotype expression of gingival fibroblasts cultured on membranes used in guided tissue regeneration.

Human gingival fibroblasts were cultured in vitro using as substrates an extracellular matrix (matrix) and polytetrafluoride (PTFE) membranes, which are used in guided tissue regeneration. To test the degree of biocompatibility of these membranes, the cellular proliferation and the accumulation of extracellular matrix (ECM) macromolecules were considered as parameters. The fibroblasts were cultured in vitro for 24 and 48 hours without serum on plastic, matrix, and PTFE membranes in the presence of 3H-thymidine, 3H-glucosamine, and 3H-proline to study the neo-synthesis of DNA, glycosaminoglycans (GAG), and collagen proteins, respectively. Studies on cell proliferation showed that fibroblasts grown on matrix membrane significantly increased 3H-thymidine incorporation, while fibroblasts grown on PTFE membrane decreased 3H-thymidine incorporation, compared to plastic used as a control. Moreover, the PTFE membrane induced a marked decrease of collagen and GAG accumulation both in the cellular and extracellular pool, while the matrix membrane provoked a decrease of the two macromolecules in the cellular pool and an increase in the extracellular one, compared to the control. The data we obtained demonstrate that matrix membranes are the most suitable to stimulate both cellular proliferation and ECM macromolecule accumulation.

Adult↗
PubMed1997

[Etiopathogenic hypotheses on dental ankylosis].

The authors review the literature about the different etiopathogenetic hypotheses of tooth ankylosis. They classified the ankylosis in three big groups: traumatic ankylosis due to direct and indirect injuries to the tooth, iatrogenic ankylosis due to unadvised maneuvers made by the dentist, and atraumatic ankylosis. The last is the most important group caused by metabolic problems and with family characteristics. Furthermore they underline the important role played by GAG and corresponding lytic enzymes in the development of atraumatic ankylosis. They described, the therapeutical procedures to be used in the different cases. The clinical cases presented are representative of the different therapeutical approaches.

Ankylosis↗
PubMed1994

[Benign obstruction of the common bile duct: what is the current role of transduodenal sphincteroplasty?].

This paper is a critical review of the clinical records of 20 patients who underwent a Transduodenal Sphincteroplasty (PSP), from October 1990 to January 1992 at our Department (General Surgery). The age was 64.9 (14.2) years (mean and standard deviation), but 14 (70%) of those patients were older than 60 (range: 63 to 89) and 9 (45%) were in the 8th up to 9th decade of their lives. In 16 patients PSP was performed at the same time as cholecystectomy. Common bile duct (CBD) exploration was decided in 11 patients only on the basis of the intraoperative cholangiographic findings (evidence of CBD stones and/or benign stenosis of the Papilla of Vater) as demonstration of the permanent role of this examination in biliary surgery. Among the patients who underwent PSP some time after cholecystectomy, one had a lesion of the choledochus, sustained when he was cholecystectomized 15 days before. Because of the fact that recovery was prompt and definitely uneventful, PSP together with the infusion of somatostatin (SMTN) can be considered a useful approach to the treatment of the biliary fistula.

Aged↗
PubMed1993

Conservative management of traumatic chylothorax: a case report.

A case is presented of a right traumatic chylothorax, secondary to thoracic trauma with bilateral posterior eleventh rib fracture, treated by total parenteral nutrition and pleural drainage, with resolution within 2 weeks. On the basis of this clinical report and of a review of the literature, it is concluded that adequate conservative management should be initially the treatment of choice. Surgical treatment should be reserved to the cases in which clinical improvement does not occur within 2 weeks, and should consist of supradiaphragmatic thoracic duct ligation. Thoracoscopic fibrin glue injection has recently been described as a possible alternative treatment.

Adult↗
PubMed1993

Abdominal aortic aneurysmectomy associated with a native iliac kidney. Case report.

Abdominal aortic aneurysm (AAA) repair associated with a pelvic kidney is extremely rare. To date only 14 cases have been reported in the literature. The main problem during aortic cross clamping is kidney preservation. The purpose of this article is to record and additional case of AAA repair associated with a native pelvic kidney. The preservation has been successfully achieved by a distal aortic double clamping.

Aged↗
PubMed1989

Extraperitoneal aorticobifemoral grafts.

Out of 436 patients operated on using aorticobifemoral grafting, 60 cases (mean age 66) had an extra-peritoneal approach to the abdominal aorta. 28 patients underwent aorticobifemoral revascularization, three of them had, in addition visceral artery grafts. In the 60 cases, perioperative mortality was 1.7%. The extra-peritoneal approach to the abdominal aorta is safer than the intraperitoneal approach, because it reduces the risk of shock connected with the large laparotomy. It is emphasized that, by using an extraperitoneal approach, a greater number of elderly patients can be considered suitable for aorticobifemoral grafts.

Adult↗