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Biomedical subjects

A M Lacy

Publications and source records attributed to A M Lacy.

At least 19 recordsLinked to original sources
PubMed1992

Long-term effects of distal splenorenal shunt on hepatic hemodynamics and liver function in patients with cirrhosis: importance of reversal of portal blood flow.

We studied 23 patients with cirrhosis who had undergone retroperitoneal distal splenorenal shunt without portal-azygos disconnection more than 2 yr earlier. We investigated the suitability of the Doppler technique (ultrasound + Doppler) to assess the patency and blood flow direction through the portal vein and the distal splenorenal shunt and its correlation with the continuous thermal dilution technique. The study also assessed the influence of the distal splenorenal shunt and time after surgery on portal perfusion and liver function. Ultrasound + Doppler distal splenorenal shunt thrombosis in two patients; however, none was confirmed by continuous thermal dilution. Ultrasound + Doppler flowmetry was possible in 19 patients (83%) (mean, 1.58 +/- 0.53 L/min). Distal splenorenal shunt continuous thermal dilution measurements were performed in all patients (100%), (mean, 1.65 +/- 0.5 L/min). Good correlation was seen between them (r = 0.66). Ultrasound + Doppler of the portal vein showed a hepatopetal flow in 16 patients (69.9%). Hepatic blood flow was significantly higher in patients with hepatopetal flow (p = 0.003). Hepatic clearance and intrinsic hepatic clearance of indocyanine green were significantly lower in patients with hepatofugal flow. Patients with hepatofugal flow had a higher incidence of chronic encephalopathy. None of the patients with a follow-up of less than 4 yr exhibited hepatofugal flow, whereas 7 of the 16 patients with a longer follow-up had hepatofugal flow (43.7%). The difference was statistically significant (p = 0.04). This study suggests that ultrasound + Doppler sonography may provide useful data in the evaluation of the patency and blood flow direction through the portal vein and the distal splenorenal shunt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The use of the University of Wisconsin (UW) and Euro-Collins (EC) solutions either alone or in a combined method.

From June 1988 to October 1990, a total of 100 orthotopic liver transplantations (OLTs) in 91 patients were performed at the Hospital Clínic of Barcelona. Euro-Collins (EC) solution was used as the flush and storage solution in 29 livers, and the University of Wisconsin (UW) solution was used in 24. A combined method, consisting of flushing and harvesting the liver with UW solution through the portal vein and with EC solution through the aorta, was used in the remaining 47 livers. Livers harvested using such a combined method showed substantially better postoperative function in terms of AST, ALT, and prothrombin activity than those harvested in EC solution alone. Although AST and ALT values were lower in patients whose livers were harvested using the combined method than with UW alone, differences were not significant. On the other hand, prothrombin activity was consistently better in the UW group. Bilirubin levels, platelet count, and bile output showed no difference among the three groups. We conclude that the combined use of UW and EC solutions for flushing and harvesting is not hazardous to human liver preservation and, in fact, may considerably reduce the amount of UW solution needed and, consequently, the costs.

Adenosine↗
PubMed1992

In vitro microleakage at the gingival margin of porcelain and resin veneers.

This in vitro study investigated the effect of dental surface treatments on the seal of porcelain and resin laminate veneers to tooth structure. Nine groups of 20 teeth were prepared for labial veneers--six groups with the apical margin of the veneer in dentin, two groups with the veneer wholly bordered by enamel, and one group with the apical margin coincident with the apical margin of a previously placed glass ionomer restoration. The teeth were treated with a variety of dentin-bonding agents prior to restoration of eight groups with porcelain veneers and one group with Visio-Gem microfilled resin veneers. After placement, the veneers were stored in water for 4 days, then subjected to thermocycling before silver staining and sectioning. Results showed no leakage around the margins of the veneers wholly bordered by enamel. Complete leakage was found around the glass ionomer restorations, and nearly total leakage was found along the resin-dentin interface of the resin veneers. The porcelain veneers that extended onto dentin showed variable but limited leakage for four of five of the dentin-bonding treatments.

Acid Etching, Dental↗
PubMed1992

Effect of bonded amalgam on the fracture resistance of teeth.

The purpose of this study was to determine whether amalgam bonded to tooth structure with an adhesive resin cement can increase the fracture resistance of restored teeth. Extracted paired upper premolars were prepared for G.V. Black type mesioocclusodistal amalgam restorations. In one tooth of each pair (the experimental group), the enamel walls were etched with phosphoric acid and were painted with an adhesive resin (Panavia), and amalgam was condensed and carved. For the other tooth in each pair (the control group), amalgam was placed in the same manner but was not etched and lined with resin. The teeth were thermocycled and mounted for testing and then were loaded until fracture. A significant difference (p less than 0.05, the paired Student's t-test) was found in the force needed to fracture the bonded amalgam group (70.5 +/- 21.6 kg) compared with that needed to fracture the conventional amalgam group (60.3 +/- 16.8 kg). SEM examination of fractures at the interface occurred predominantly within the resin.

Acid Etching, Dental↗
PubMed1992

Use of self-curing composite resins to facilitate amalgam repair.

Resin cements, which have been shown to adhere to various metal alloys, were investigated as possible repair adhesives for dental amalgam. Test bars of repaired amalgam, formed by condensing new alloy against previously set alloy with or without the use of "adhesive" resins, were subjected to three-point bending measurements of transverse fracture strength. The results indicated that application of adhesive resin did not improve the breaking strength of the repaired specimens from that of specimens prepared without the use of such resins. The breaking strength of all repaired specimens was approximately 15% of the transverse fracture strength of the original intact amalgam bars. Scanning electron microscopy revealed that there was an intermixing of fresh amalgam and unset interfacial resin, which led to mechanical bonding of these materials, but there was no evidence of adhesion of the resin to the previously set amalgam.

Acrylic Resins↗
PubMed1991

The processed silicone gingival prosthesis: a simple solution to a complex problem.

The clinical use of a flexible, removable gingival prosthesis that is constructed by the dental laboratory on a stone cast to reproduce interdental spaces resulting from gingival recession is described. The thin prosthesis replaces lost gingival tissue and is retained by extension into interproximal undercuts. It is readily removable for convenient home care.

Dental Veneers↗
PubMed1991

Improved retention for bonded cast metal rests: a case report.

This article describes improvements in retention of resin-bonded, cast metal rest seats that utilize cast pins for additional stabilization and resistance to intraoral forces of dislodgment. This method combines the classic design of pin-ledge retainers with the resin-bonded concept of retention to provide a reliable and stable, but conservative, method of altering tooth form to support removable partial dentures.

Dental Abutments↗
PubMed1991

A clinical technique for bonding gold castings to teeth.

A clinical technique is presented that allows practitioners to use adhesive bonding techniques to improve the retention and seal of gold castings. At the time of delivery of a gold casting, the preparation is treated with a self-curing enamel and dentinal bonding agent. The internal surface of the casting is sandblasted and electroplated with tin to produce a surface suitable for bonding with a resin cement, which is virtually insoluble and is adhesive to both the metal surface and the treated tooth.

Acrylic Resins↗
PubMed1987

Orientation of enzymic domains in tryptophan synthase of Neurospora crassa: an immunoblot analysis of TRP3 mutant products.

Extracts of 52 TRP3 mutants of Neurospora crassa were tested for the presence of serologically cross-reacting material by the method of electrophoretic blot analysis. The test antigen was obtained by excision of lightly stained bands of denatured pure tryptophan synthase after SDS-polyacrylamide gel electrophoresis. Rabbit antisera raised against this antigen neutralized and precipitated native tryptophan synthase. Of the 52 strains, 19 exhibited banding patterns similar to wild type on electrophoretic blots, 25 strains gave no apparent bands, and 8 strains showed unique banding patterns. This evidence and related genetic fine structure mapping data indicate that strains exhibiting banding patterns similar to wild type carry missense mutations. Strains which did not exhibit any obvious bands may have resulted from certain kinds of missense or nonsense mutations or from frameshift mutations or extended deletions. Strains exhibiting unique banding patterns on electrophoretic blots were interpreted as carrying chain-terminating mutations or deletions. Genetic fine structure mapping data place the mutant lesions of these strains in a linear order corresponding to the apparent molecular weights of the crossreacting protein fragments which they exhibit. The direction of transcription and translation of the TRP3 locus in Neurospora was inferred from these relationships. The apparent organization of the Neurospora TRP3 gene is consistent with that ascribed to the Saccharomyces TRP5 system and suggests that the N-terminal portion of the protein corresponds to the "A" protein of the Escherichia coli system and that the C-terminal portion of the protein corresponds to the "B" protein of the bacterial system.

Crosses, Genetic↗
PubMed1987

A critical look at posterior composite restorations.

The limited serviceability of posterior composite resins relates not only to the lack of a durable composite material, but also to other factors such as postoperative sensitivity, difficulty in achieving proximal contacts, marginal leakage, and recurrent caries. However, most of the problems can be overcome by attention to materials used, selection of teeth to be restored, and clinical techniques.

Bicuspid↗