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Biomedical subjects

J A Scott

Publications and source records attributed to J A Scott.

At least 19 recordsLinked to original sources
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.

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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

Diagnosing multiple parasitic infections: trypanosomiasis, loiasis and schistosomiasis in a single case.

A case is reported of a 32-year-old traveller with loiasis, schistosomiasis and African trypanosomiasis. The patient had been working in oil exploration in Nigeria and Gabon and presented with Calabar swellings and carpal tunnel syndrome. Serology for all 3 diseases was positive but microfilariae of Loa loa and ova of schistosomiasis were not found. Treatment with diethylcarbamazine and praziquantel was given for loiasis and schistosomiasis respectively. Trypanosomes were isolated from a lymph node aspirate only after repetition of the procedure 2 months later and the patient was treated with suramin. He developed a drug induced nephritis and was then treated successfully with alpha-difluoromethylornithine. There is a discussion of the difficulties encountered making these diagnoses in Europeans particularly where there are atypical clinical features. The risks of rural work in West Africa are noted and the importance of considering all parasitic diseases relevant to the travel/occupational history is emphasised.

Adult↗
PubMed1991

The effect of silane on shear bond strengths of etched cast metal restorations.

This study investigated the effect of a silane on the shear bond strength between an electrolytically etched Ni-Cr alloy and bovine enamel. The effect of time delay after etching and after silaning was also investigated. The results showed there to be a significant increase in bond strength when silane was used and bonding carried out immediately following silaning. However, a delay in bonding of even one hour after silaning significantly reduced bond strength. For periods up to one week, delay in silaning after etching had no effect on bond strength.

Animals↗
PubMed1990

Sites of cadmium uptake in bacteria used for biosorption.

Electron microscopy and x-ray spectroscopy were used to determine location and type of cadmium biosorption on and in bacteria, some of which produced extracellular polymers. Examined Arthrobacter and Pseudomonas species appear to have detoxification systems that precipitate cadmium internally irrespective of whether or not they excrete polymers. Capsular Klebsiella aerogenes strains showed minimal intracellular uptake but over a 5-100 mg dm-3 Cd range produced the highest net metal removal levels due to significant extracellular adsorption.

Arthrobacter↗
PubMed1979

Medical writing.

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Writing↗
PubMed1978

Factors affecting pituitary gonadotropin function in users of oral contraceptive steroids.

In order to determine whether certain factors influence the direct pituitary suppressive effect of contraceptive steroid, 50 subjects who had used various formulations of oral contraceptive steroids for periods of time ranging from one to nine years were stimulated with 50 microgram of gonadotropin-releasing hormone (GnRH) during the last week of oral contraceptive ingestion. The response of lutinizing hormone (LH) and follicle-stimulating hormone (FSH) was compared to the results obtained in nine control subjects with regard to: (1) age of subject. (2) type of contraceptive formulation used, and (3) length of use. Prestimulation levels of LH and FSH, respectively, were significantly decreased in 37 (74 per cent) and 42 (84 per cent) of the subjects. Following GnRH stimulation, peak responses of serum LH and FSH, respectively, were also significantly lower than those in the control subjects in 40 (80 per cent) and 45 (90 per cent of the subjects. The degree of suppression of pituitary gonadotropins, both before and after GnRH administration was significantly correlated with the type of steroid formulation used, being greatest with a combination of d-norgestrel and ethinyl estradiol. No correlation was found with length of use of oral contraceptives or age of the subjects.

Adult↗
PubMed1976

An outbreak of S typhimurium in sheep and its consequences.

An outbreak of Salmonella typhimurium in an upland sheep flock was characterised by rapid spread and heavy mortalities in ewes and young lambs. Clinical signs included diarrhoea and abortion. Abomasitis was the most striking and consistent post mortem lesion. Vaccination was the only control method that was apparently successful. Infection also occurred in the cattle, farm personnel, and a dog. Following the outbreak, pasture contamination and excreting cattle provided a reservoir of infection so that contamination of water courses and sporadic cases occurred over a year later.

Animals↗
PubMed1975

Effect of briefly heating cyclophosphamide solutions.

Solutions containing cyclophosphamide monohydrate were heated to 50 C, 60 C, 70 C and 80 C for 15 minutes and then assayed for potency. Solutions heated to 50 Cor 60 C did not change appreciably; those heated to 70 C and 80 C assayed at 90.2% and 77.5%, respectively, of initial potency. The values compared well with those calculated using the Arrhenius equation. It is concluded that warming vials of cyclophosphamide monohydrate after adding an aqueous vehicle (in order to achieve rapid dissolution) could decrease the potency of the final injectable product.

Cyclophosphamide↗