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Biomedical subjects

J A Scott

Publications and source records attributed to J A Scott.

At least 109 records · Page 6Linked to original sources
PubMed1994

Pulmonary embolism: prediction of the usefulness of initial ventilation-perfusion scanning with chest radiographic findings.

PURPOSE: To evaluate the usefulness of ventilation-perfusion scanning when chest radiographic findings are abnormal to decide which patients should initially undergo angiography because of suspected pulmonary embolism. MATERIALS AND METHODS: The records of 951 patients who underwent examination between April 1, 1992, and August 24, 1993, were reviewed, and the results of ventilation-perfusion scanning and chest radiography were correlated. RESULTS: Approximately 8% of patients with radiographic findings of no acute disease, pleural effusion, and linear atelectasis had high-probability ventilation-perfusion scans. Pulmonary edema and parenchymal consolidation categories had fewer high-probability studies (3% and 1%, respectively; P < .01). The chance of obtaining a nondiagnostic result was similar for the first three categories (12%) but was more likely for pleural effusion and parenchymal consolidation (36% and 82%, respectively; P < .01). CONCLUSION: The results of ventilation-perfusion scanning are not useful with focal radiographic consolidation. It may be appropriate to proceed directly to pulmonary angiography in many of these patients.

Humans↗
PubMed1993

Co-occurrence of schizophrenia and Treacher Collins syndrome.

This is the first report of an individual with several congenital abnormalities, including those suggestive of Treacher Collins syndrome, and an atypical schizophrenic illness. Cytogenetic studies have failed to detect any recognizable chromosomal abnormality.

Humans↗
PubMed1993

DNA fingerprints of Mycobacterium tuberculosis do not change during the development of rifampicin resistance.

Drug-resistant tuberculosis has become a major public health problem. Resistance to rifampicin probably arises through mutations in the mycobacterial RNA polymerase. Patients may acquire rifampicin resistant tuberculosis by three mechanisms: (1) infection with a resistant organism, (2) selection of a sub-population of resistant organisms that remain contained whilst the more virulent wild type is present, (3) mutations within the population of bacilli causing the original infection. Sequential isolates of Mycobacterium tuberculosis were collected from 2 patients who developed rifampicin resistance whilst on treatment. One patient was immunosuppressed with HIV-infection; in the other patient the original isolate was also resistant to isoniazid. DNA fingerprinting techniques were used to type the isolates. No differences were found between the fingerprints of isolates from before and after the development of resistance. These data suggest that the third of the mechanisms listed above was responsible for the acquisition of rifampicin resistance in these 2 patients.

Adult↗
PubMed1993

Neural network analysis of ventilation-perfusion lung scans.

A neural network model was constructed to interpret ventilation-perfusion (V/Q) lung scans. This model was trained with data from 100 consecutive V/Q scans with pulmonary angiographic correlation. The network was constructed from 28 input parameters that described various standard V/Q findings, which were fed into a single hidden layer that contained 10-20 nodes. The network output indicated the percentage probability of pulmonary embolism for each set of findings on V/Q scans. This network was then used to classify 28 new scans; the resultant classifications were compared with the rankings of an experienced observer who read the scans without knowledge of the correlative angiographic data. The network with 15 hidden nodes outperformed the experienced observer in prediction of the likelihood of pulmonary embolism in the 28-case test set (P = .039). The neural network has several advantages over current algorithms for interpretation of V/Q scans, including the ability to synthesize many variables into a single conclusion and to learn, or modify itself, at exposure to additional data.

Adult↗
PubMed1993

Identification of single specimens of the Anopheles gambiae complex by the polymerase chain reaction.

A ribosomal DNA-polymerase chain reaction (PCR) method has been developed for species identification of individuals of the five most widespread members of the Anopheles gambiae complex, a group of morphologically indistinguishable sibling mosquito species that includes the major vectors of malaria in Africa. The method, which is based on species-specific nucleotide sequences in the ribosomal DNA intergenic spacers, may be used to identify both species and interspecies hybrids, regardless of life stage, using either extracted DNA or fragments of a specimen. Intact portions of a mosquito as small as an egg or the segment of one leg may be placed directly into the PCR mixture for amplification and analysis. The method uses a cocktail of five 20-base oligonucleotides to identify An. gambiae, An. arabiensis, An. quadriannnulatus, and either An. melas in western Africa or An. melas in eastern and southern Africa.

Animals↗
PubMed1993

Do diagnostic algorithms always produce a uniform lung scan interpretation?

Several algorithms have been devised to assist in the interpretation of ventilation-perfusion (V/Q) scans performed to diagnose pulmonary embolism. The degree to which adherence to a single algorithm facilitates diagnostic homogeneity among different readers, however, has been little investigated. We evaluated the individual variability in V/Q lung scan interpretation in a large, academic nuclear medicine division to determine the degree of interpretive heterogeneity among a group of physicians all using the same image interpretation algorithm. Ventilation-perfusion scan interpretive patterns and the diagnostic accuracy of individual physicians were evaluated using quantitative parameters to establish group norms and to detect variations from these norms. The performance of each reader was tracked over a 4 yr period. There was a significant variation in V/Q interpretive patterns and diagnostic accuracy between readers despite the attempted use of a uniform diagnostic algorithm. Subgroups of interpretive styles could be defined based on the percentage of intermediate (including both indeterminate and intermediate categories) scans read. Although there was significant variation in diagnostic accuracy among readers, there was no obvious correlation between accuracy and reading style except that the most nonstandard diagnostic patterns were associated with the most variable diagnostic accuracy. These data show a measurable variation in interpretive patterns and accuracy among multiple readers of V/Q scans despite attempted group adherence to an established diagnostic algorithm.

Algorithms↗
PubMed1992

The plane of fracture and shear bond strength of three composite inlay systems.

Composite inlays have been introduced to overcome some of the problems encountered with direct placement techniques. However, some doubt has been expressed about the strength of the bond between the inlay surface and the composite luting cement due to the decreased number of C = C bonds remaining following supercuring of the inlay. This study investigated the bond strength of three composite inlay systems to etched bovine enamel and recorded the plane of fracture of the samples. The bond strength of one system was significantly greater than that of the other groups and was increased by the application of an unfilled resin enamel bonding agent. Unfilled resin application did not significantly alter the other systems tested. In only one of the systems tested was the inlay/composite cement bond found to be the weak link in the bonding procedure. In this group, the application of the manufacturer's specially formulated bond enhancer did not lead to an increase in bond strength.

Acrylates↗
PubMed1992

Meteorologic influences on the frequency of pulmonary embolism.

RATIONALE AND OBJECTIVES: Reports published earlier this century suggested that meteorologic factors influence the incidence of pulmonary embolism. These observations were based on few patients and often lacked rigorous standards of evidence. In the current study, the authors evaluate the association between barometric pressure changes and pulmonary embolism using radionuclide ventilation-perfusion (V/Q) scan data. METHODS: Daily interpretation data for V/Q lung scans were correlated retrospectively with daily local barometric pressure changes over a 7-year period. RESULTS: The incidence of pulmonary embolic disease was significantly related to a decrease in barometric pressure during the 3 days preceding clinical presentation. CONCLUSIONS: Meteorologic factors are less important than better-known risk factors for pulmonary embolism; however, their effect is demonstrable in a large data sample. This work confirms previously published associations between barometric pressure changes and the incidence of pulmonary embolism.

Analysis of Variance↗
PubMed1992

Microleakage of a composite inlay system.

This study investigated the marginal seal of resin composite inlays in dentin and enamel when either unfilled resin or a second or third generation dentin bonding agent is used. Standardized mesial and distal inlay cavities were cut in 135 human third molar teeth. The teeth were randomly divided into 9 groups and inlays fabricated in a hybrid resin composite inlay material. Each group of teeth was then treated with one of 8 dentin bonding agents or an unfilled resin and cemented with a dual curing resin cement. Each group was stored in deionized water for 1 week, thermocycled between 5 degrees C, 37 degrees C and 55 degrees C for 500 cycles, then placed in 2% methylene blue solution for 15 hours. Following this the teeth were sectioned and scored for the degree of leakage observed. Marginal microleakage was minimal at enamel margins, however there was marked leakage, even when a dentin bonding agent was used, on the dentin side. Only two dentin bonding agents proved more effective than unfilled resin and in only one case was the leakage not significantly worse than in enamel.

Analysis of Variance↗
PubMed1992

Anatomic divisions.

Explore the source record for details and available documents.

Acupuncture Points↗
PubMed1991

Silane effects on luting resin bond to a Ni-Cr alloy.

This study investigates the effect of a silane coupling agent on the shear bond strength of four commercially available resin luting systems (two of which rely on mechanical retention and two which have a chemical bond to metal) when bonding a prepared Ni-Cr alloy to etched bovine enamel. Silane application reduced the bond strengths of the two chemically adhesive resins and increased the bond strength of one of the mechanically retained resins. For the other mechanically retained resin, silane application did not significantly increase the bond strength but the plane of fracture changed from resin/metal to resin/enamel: from this an increase in metal resin bond strength can be inferred.

Acid Etching, Dental↗
PubMed1991

Nutrition education in supermarkets: the Lifestyle 2000 experience.

A 15-week supermarket-based nutrition education program was conducted as part of a larger multiple-strategy community-wide health promotion project. The program consisted of point-of-purchase materials displayed in the supermarkets and was supported by a mass media campaign and promotional activities such as competitions, taste testing and cooking demonstrations. The objective of the program was to promote the selection and purchase of low-fat foods, specifically low-fat dairy products, fresh fruit and vegetables, bread and cereal products. Awareness of the promotion was high, with some self-reported behaviour change. Supermarkets are potential sites for public health nutrition education and recommendations are made for improving the effectiveness of point-of-purchase promotions.

Australia↗