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Biomedical subjects

R R White

Publications and source records attributed to R R White.

At least 19 recordsLinked to original sources
PubMed1995

Infection control in general practice: results of a questionnaire survey.

BACKGROUND: Infection control is an important aspect of quality of care. General practitioners (GPs) have a high throughput of patients, some attending because of a communicable disease, others for investigations or minor operations. This situation provides an opportunity for the spread of infections. This study looked at the development of practice policies on infection control and the need for further information and guidelines. METHODS: A postal questionnaire was sent to 117 practices in a single Family Health Services Authority. The questionnaire contained sections to be completed by a GP and a practice nurse in each surgery. RESULTS: A response rate of 74.5 per cent was obtained. Of the practices replying, 85 per cent did not have a written infection control policy. Sterilization of instruments was carried out in over 90 per cent of surgeries. Autoclaves were used in almost four-fifths of these practices; most did not have any written procedures covering their use. Few practices provided information on procedures for infected patients or staff. A third of practices did not have a needlestick policy, and sharps incidents were not recorded in 42 per cent of surgeries. Three-quarters of practices said that they would welcome guidelines on infection control. Half of the practice nurses thought that more training on infection control was required. CONCLUSIONS: The need for more training and the implications of the information from the study on the development and implementation of guidelines are discussed. Recommendations are made which aim to increase the awareness of this issue by means of guidelines and training focused on practice nurses.

Disinfection↗
PubMed1994

Neuropeptides are potent modulators of human in vitro immunoglobulin E synthesis.

We determined the effect of adrenocorticotropin hormone (ACTH) on the regulation of IgE synthesis. Depending on the concentration, ACTH enhanced or inhibited IgE synthesis in a culture system where IgE synthesis was induced with interleukin-4 (IL-4) and anti-CD40 monoclonal antibody in peripheral blood mononuclear cells. Similar effects on IgE synthesis were observed by adding ACTH-related peptides, e.g. corticotropin-releasing factor (CRF), the inducer of ACTH, or alpha-melanocyte stimulating hormone (alpha-MSH), a cleavage product of ACTH. However, ACTH had no effect on IgG or IgM synthesis in this culture system. ACTH did not act directly on either B or T cells as there was no influence on IgE synthesis in a system using purified B cells alone or co-cultured with T cells. The effect of ACTH on IgE synthesis was mediated by accessory cells. This was shown by priming purified CD14-positive monocytes with ACTH and reconstitution experiments. Therefore, these findings suggest that ACTH and the related peptides CRF and alpha-MSH can influence the microenvironment modulating an IL-4 and anti-CD40 monoclonal antibody driven class switching to IgE via accessory cells.

Adrenocorticotropic Hormone↗
PubMed1994

A comparison of 2.0% chlorhexidine gluconate and 5.25% sodium hypochlorite as antimicrobial endodontic irrigants.

Sodium hypochlorite, as an endodontic irrigant, poses problems including toxicity, odor, and discoloration of operatory items. An equally effective, but safer irrigant is desirable. Therefore, we compared the antimicrobial activity of 2.0% chlorhexidine gluconate with that of 5.25% sodium hypochlorite in an in vitro root canal system. Freshly extracted human teeth with pulpal pathosis were instrumented using chlorhexidine, sodium hypochlorite, or saline as irrigants. Microbiological samples were taken from the teeth immediately after accessing the canal, after instrumentation and irrigation, and after standing in an anaerobic atmosphere for 24 h. Irrigation with chlorhexidine or sodium hypochlorite significantly reduced the numbers of postirrigant positive cultures and colony-forming units compared with saline-irrigated teeth. The number of postirrigant positive cultures and the number of colony-forming units in positive cultures obtained from chlorhexidine-treated teeth were lower than the numbers obtained from sodium hypochlorite-treated teeth, but the differences were not statistically significant.

Analysis of Variance↗
PubMed1993

Crotalidae envenomation in children.

Poisonous snakebites cause a severe envenomation syndrome in children, yet treatment remains controversial. Sixty-seven patients were treated for poisonous snakebites at our institution between 1975 and 1990; 18 were children < or = 12 years old. There were 13 rattlesnake bites, 4 copperhead bites, and 1 unidentified bite. Initial management included intravenous fluids and antibiotic administration, laboratory studies, tetanus prophylaxis, affected limb elevation, and a limited excision of the bite site in the emergency room. Antivenin was administered only if signs of systemic involvement such as shock, coagulopathy, gastrointestinal cramping, or neurological involvement were present. Children developed systemic involvement 72% of the time, 9 children (50%) developed coagulopathy. Consequently, 11 (61%) children received antivenin. The dose of antivenin they received was 3.2 ml/kg and the children tolerated it well with only 36% of them demonstrating adverse reactions to the antivenin. Clinically, the pediatric patients demonstrated signs and symptoms of a fulminant envenomation syndrome (8 days, average hospital stay), yet, they had a good eventual outcome. Only 11% of children reported long-term morbidity. No deaths occurred and 100% of patients were able to return to full preinjury activities. We conclude that Crotalidae envenomation in children is a serious disease and warrants hospitalization, early surgical involvement, and frequent use of antivenin.

Animals↗
PubMed1993

A possible late onset variation of Papillon-Lefèvre syndrome: report of 3 cases.

Three unusual cases of Papillon-Lefèvre syndrome with late onset of features and relatively mild periodontal disease are presented. These examples confirm some of the late onset of features and mild periodontal presentation of a previous case report. Bacteriologic associations, polymorphonuclear leukocyte chemotactic, phagocytic, and bactericidal activity, and therapeutics with regard to this syndrome are discussed.

Adult↗
PubMed1992

Comparative tissue tolerance of a new endodontic sealer.

An experimental radiopaque resin root canal sealer was tested for tissue biocompatibility in rat connective tissue. The controls were four widely used sealers: Sealapex, Kerr's sealer, AH-26, and Roth's sealer. Polyethylene tubes were filled with the sealers and allowed to set for 24 hours in 100% humidity. Each sealer was implanted in the connective tissue of Sprague-Dawley rats and removed after 3, 10, 20, 30, and 60 days, fixed, and histologically prepared for light microscope evaluation. At each time period there was practically no difference in the reaction of all the sealers. By 60 days, the total picture was one of well-tolerated biocompatibility.

Animals↗
PubMed1992

Microleakage--full crowns and the dental pulp.

Recent studies have described microleakage under full crowns cemented with several different cements. This study tested three different types of crown margin preparations--a chamfer, a shoulder, and a shoulder plus a bevel to determine whether or not the margin preparation could affect microleakage. All crowns were cemented with zinc phosphate cement. The crowns were tested for leakage in thermocycled dye. All crowns demonstrated significant leakage following the path of the dentinal tubules into the pulp. This could possibly be one of the causes of pulpal inflammation and even pulpal death under full crowns.

Crowns↗
PubMed1992

Neutrophil modulation by Actinobacillus actinomycetemcomitans. I. Chemotaxis, surface receptor expression and F-actin polymerization.

Localized juvenile periodontitis is an early onset periodontitis, usually localized to molars and incisors. Patients usually present with decreased chemotaxis of systemic neutrophils (PMNs) and infection with Actinobacillus actinomycetemcomitans. The pathogenic mechanisms involved have not been clarified. The purpose of this study was to determine if an extract of A. actinomycetemcomitans could induce changes in PMN chemotaxis similar to those reported in LJP patients. It was demonstrated that the bacterial extract was chemotactic for neutrophils. When neutrophils were pre-incubated with the bacterial extract, chemotaxis toward zymosan-activated serum, FMLP and the bacterial extract was inhibited in two different chemotaxis assays (Boyden chamber and under-agarose). Bacterial extract had no effect on random migration in either assay. Pre-incubation with the extract induced increased expression of CD11b/CD18 (Mac-1), Gp110, and FMLP receptors and increased F-actin polymerization following FMLP or PMA stimulation compared to cells not treated with the extract. Treatment of the bacterial extract with proteinase K or phenol extraction reversed the PMN chemotaxis inhibition activity, but increased significantly the random migration of PMNs. Heating the bacterial extract to 56 degrees C had no effect on its activity. The component(s) in the bacterial extract that inhibits chemotaxis is therefore a protein(s), not sensitive to 56 degrees C, and is not endotoxin. This study suggests that A. actinomycetemcomitans may contribute to the pathogenesis of localized juvenile periodontitis by inhibiting chemotaxis. Interference with chemotaxis by A. actinomycetemcomitans, however, occurs through a mechanism other than inhibition of actin assembly, reduction of CD11b/CD18 or Gp110 expression, or blockage/downregulation of FMLP receptors.

Actins↗
PubMed1992

Neutrophil modulation by Actinobacillus actinomycetemcomitans. II. Phagocytosis and development of respiratory burst.

Compromised neutrophil function has been found in a number of patients with localized juvenile periodontitis (LJP), although the pathogenic mechanism is unknown. Since infection with Actinobacillus actinomycetemcomitans is frequently found in patients with LJP, we have evaluated in vitro the effect of a bacterial extract of A. actinomycetemcomitans on the development of the respiratory burst by neutrophils. Pre-incubation of neutrophils with bacterial extract increased H2O2 induced by FMLP and zymosan in a dose-dependent fashion. Substitution of FMLP for bacterial extract produced similar results. Moreover, FMLP and bacterial extract had an additive effect on superoxide production following phagocytosis of zymosan. In contrast, bacterial extract significantly decreased PMA-stimulated H2O2, but pre-incubation with FMLP instead of bacterial extract failed to decrease PMA-stimulated H2O2. Bacterial extract did not change the percentage of cells activated by FMLP, opsonized zymosan, or PMA. Heat-treated bacterial extract induced effects similar to non-treated extract. Bacterial extract treated with proteinase K or phenol extraction increased FMLP or zymosan stimulated H2O2 equivalent to non-treated bacterial extract. In contrast, proteinase K or phenol extraction abolished the inhibitory effect of bacterial extract on PMA-stimulated H2O2 production. The bacterial extract component(s) that inhibits PMA-stimulated H2O2 is therefore a protein(s), resistant to 56 degrees C, and is not endotoxin. The partially activated state of PMNs exposed to A. actinomycetemcomitans extract, combined with their reduced ability to respond to a protein kinase C-dependent stimulus, may partially explain the abnormalities noted in LJP patients.

Adult↗
PubMed1991

Poisonous snakebite in central Texas. Possible indicators for antivenin treatment.

Sixty-seven patients hospitalized for poisonous snakebite between 1975 and 1990 were managed by elevation, tetanus prophylaxis, intravenous fluids and antibiotics, and often by a limited excision of the bite site in the Emergency Department, with sequential laboratory studies as needed. Antivenin was used for systemic envenomation, and 23 of the 67 patients (34%) received 133 vials. Thirteen of the twenty-three patients (56%) had adverse reactions to the antivenin. Two significant observations arose. First age was an indicator. Eleven of eighteen patients 12 years or younger (61%) received antivenin, whereas 12 of 49 patients older than 12 years (24%) received antivenin (p = 0.0085, Fisher's exact test). Second species of snake was an indicator. Sixty-two snakes were identified (93%). Of 39 rattlesnake (Crotalus and Sistrurus) bites, 20 patients received antivenin (53%), but of 23 copperhead and water moccasin (Agkistrodon) bites, only three patients (12.5%) received antivenin (p = 0.0025). Antivenin may be indicated for use in systemic rattlesnake envenomation, especially in younger patients.

Adolescent↗
PubMed1990

Nonunion of the proximal humerus. A review of 25 cases.

Records of 25 patients with nonunion of the proximal humerus were reviewed retrospectively. The initial fractures included 19 two-part surgical neck fractures and six three-part fractures. Fourteen fractures were treated nonoperatively and 11 surgically. Nine of 11 of the initial internal fixations were unsatisfactory. At the time of fracture 16 patients had one or more significant medical illnesses. Nonunion of the proximal humerus was associated with considerable morbidity. Patients complained of pain, stiffness, and disability in association with shoulder dysfunction. Four treatment groups were evaluated. Patients who declined treatment and patients treated with nonreamed intramedullary nails had limited shoulder motion and pain without union. Patients treated with proximal humeral hemiarthroplasty had relief of pain but limited motion despite rotator cuff reconstruction. The best results of treatment occurred after open reduction with internal fixation and bone grafting. A tension band construction that fixed the rotator cuff and proximal humerus to a plate/shaft composite was used successfully in seven patients. Although satisfactory reconstruction of nonunion of the proximal humerus can be obtained, the results of treatment in this series were only fair. Only 48% (12 of 25 patients) had good results.

Adolescent↗
PubMed1989

A silicone model method to compare three methods of preparing the root canal.

To compare the ability of three methods of preparing root canals to provide a properly shaped canal, silicone models were used. The canals of extracted teeth were prepared and filled with a silicone impression material. The teeth were dissolved, and the remaining models were studied and photographed. The hand instrument group and the SET angle were equal. The subsonic instrument did not shape a canal as well as the other two.

Dental Impression Materials↗
PubMed1989

Antibacterial effects of glass ionomers.

Glass ionomer cements have been shown to possess antimicrobial activity. Proposed mechanisms of action include acidity and fluoride. It was the purpose of this study to determine the antimicrobial effect of 11 glass ionomer cements, their individual powder and liquid components and one resin-bonded liner containing high fluoride ionomer glass against Streptococcus mutans #6715. The role of fluoride and pH in the antibacterial activity was also studied. Using agar diffusion assay methodology, the following results were obtained. All of the glass ionomer cements were inhibitory against S. mutans. The antibacterial cements and slurries that were tested for fluoride, released the ion in excess of reported minimum inhibitory values. The antimicrobial activity of the liquid components, that were tested for the effects of pH changes, was totally lost when the pH was adjusted to 5. The resin bonded liner was inactive against S. mutans and did not release inhibitory concentrations of fluoride. These results indicate that freshly-mixed glass ionomer cements are antimicrobial against S. mutans and that the mechanism of action is probably a function of both fluoride and pH although additional factors may be involved.

Dental Cements↗