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Biomedical subjects

S Lewis

Publications and source records attributed to S Lewis.

At least 19 recordsLinked to original sources
PubMed1992

Treatment of edentulous maxillae with osseointegrated implants.

Edentulous maxillae can be restored with implant supported fixed restorations containing denture teeth on a metal framework, implant-retained removable overlay prostheses, or porcelain fused-to-metal fixed prostheses. Esthetics and hygiene access are two important factors in determining the restoration best suited for each patient. Treatment planning considerations and treatment procedures for the various techniques are discussed.

Dental Implants↗
PubMed1992

Arginase is a major pathway of L-arginine metabolism in nephritic glomeruli.

L-arginine can be metabolized to nitric oxide (NO) by nitric oxide synthase (NOS) and to urea and L-ornithine by arginase. Competition between these pathways for L-arginine in inflammatory sites has been suggested. In experimental glomerulonephritis glomeruli produce nitrite; a major source is macrophages. We hypothesized that arginase is present in glomeruli and may compete for substrate with NOS in glomerulonephritis. Therefore we examined both pathways in isolated nephritic glomeruli and peritoneal macrophages. Arginase activity was present in glomeruli, increased by > 500% in nephritic glomeruli compared to controls, and was predominant over NOS. Activity increased with L-NMMA (a NOS inhibitor), but this trend did not reach statistical significance. In macrophages both pathways were present; NOS predominated basally but this was reversed by L-NMMA. In contrast with glomeruli macrophage arginase activity increased after LPS stimulation. Levels of macrophage arginase activity could not account for activity in nephritic glomeruli, suggesting another source of arginase. This is the first demonstration of high arginase activity of nephritic glomeruli. Competition between arginase and NOS pathways suggests a regulatory mechanism of L-arginine metabolism within the glomerulus, with implications for the pathogenesis of injury and scarring in glomerulonephritis.

Amino Acid Oxidoreductases↗
PubMed1992

Carbon monoxide exposure in blast furnace workers.

This study investigated the occupational exposure to carbon monoxide (CO) of a group of blast furnace workers from an integrated steelworks, compared to a control group having no significant occupational CO exposure from other areas in the same works. The study was undertaken in 1984 at Port Kembla, New South Wales. Carboxyhaemoglobin (COHb) levels before and after an eight-hour work shift were measured in 98 male steelworkers: 52 from two CO-exposed iron blast furnaces and 46 controls from production areas in the same steelworks. The sample was stratified by smoking habits. Environmental air CO levels had been found to be consistently higher on one furnace than on the other. Absorption of CO from the working environment occurred in workers on the blast furnace with higher CO levels, regardless of smoking habits. On this blast furnace, some readings of COHb levels after a workshift in nonsmokers approached the proposed Australian occupational limit of 5 per cent COHb saturation. Overall, workers with the highest occupational exposure who smoked most heavily had the highest absorption of CO over a work shift. Biological monitoring gives an accurate measure of individual worker 'dose' of CO from all sources. Both environmental monitoring and biological monitoring need to be included as part of a program for controlling occupational CO exposure.

Breath Tests↗
PubMed1992

Clinical correlates of sway in elderly people living at home.

Postural sway has been noted to increase with advancing age and to correlate with a wide variety of clinical features. The relationships between sway and various clinical features were explored in a group of elderly subjects living at home and free from neurological illness and severe incapacity. Each subject underwent a thorough physical examination and sway was measured in the anteroposterior and lateral planes with eyes open and closed using a modified Wright's ataxiameter. Vibration sense was the only clinical feature to show a consistent relationship with all 4 measurements of sway in men. Age showed only a weak and inconsistent relationship to sway in both men and women. Weak but inconsistent relationships were noted between sway and mental function, tone, passive joint movement, antidepressant and tranquilliser therapy. This suggests that dorsal column function is of prime importance in the maintenance of balance and that the previously noted increase in postural sway with advancing age may have been exaggerated by the presence of disease processes.

Aged↗
PubMed1992

Relationship between chemical-induced fragile sites and chromosomal breakpoints in malignant cells in children.

Many fragile sites in the human genome occur at or near chromosomal breakpoints reportedly involved in translocations of DNA material in neoplastic cells. This fact has led some investigators to postulate that fragile sites have a pathogenic role in human neoplasia. To learn whether caffeine-induced fragile sites relate to breakpoints found in the neoplastic cells of an individual patient, we studied lymphocytes from the peripheral blood of 32 patients in remission from malignant disease. Lymphocytes were cultured in medium containing either 5-Fluoro-2'-deoxyuridine (FdU) or FdU plus caffeine, and G-banded metaphases were examined for nonrandom breaks. Analyses of completely G-banded malignant cell chromosomes from 31 of the 32 patients were available for comparison. In only once case, a 5-year-old child with acute lymphoblastic leukemia, did a caffeine-induced fragile site (1q44) coincide with a breakpoint in the neoplastic cells [dup(1)(q21-->q44)]. Our findings suggest that chromosomal abnormalities in childhood malignancies cannot generally be explained by the presence of FdU- or FdU plus caffeine-induced fragile sites.

Adolescent↗
PubMed1992

Histomorphometry of bone apposition around three types of endosseous dental implants.

Three different types of commercially available dental implants (Nobelpharma, IMZ, and Integral) were implanted in the edentulous mandibles of seven adult mongrel dogs. Twenty-one implants were harvested with block sections after 12 weeks and embedded in polymethyl methacrylate resin. Undecalcified sections were prepared with the sectioning-grinding technique. The percentage of bone contacting the implant surface was measured with a self-designed histomorphometry method using a millimeter grid in a stereomicroscope. The results demonstrated a significantly higher percentage of bone along the hydroxyapatite-coated implant than that seen with the titanium-surfaced implant types.

Alveolar Process↗
PubMed1992

Which calcium channel blocker for ischaemic heart disease?

Calcium channel blockers have been available since the early 1960s. Extensive research has been undertaken to evaluate their usefulness in the treatment of patients with ischaemic heart disease. We have reviewed the pharmacology of these drugs and the major clinical trials. In particular, we have examined the effect of calcium channel blockers on the progression of atheroma, and their role in the following clinical settings: following myocardial infarction, following non-Q-wave myocardial infarction, and in unstable angina.

Angina, Unstable↗
PubMed1992

Gaucher's disease.

Explore the source record for details and available documents.

Gaucher Disease↗
PubMed1992

Identifying and treating patients with panic attacks.

Panic disorder occurs in up to 3 percent of the population and can be socially, emotionally and occupationally disabling. A thorough clinical evaluation is crucial to exclude illnesses with similar presentations, particularly acute cardiac, gastrointestinal or neurologic disease. The noradrenergic nervous system is involved in panic attacks. These attacks are described as sudden, unexpected episodes of intense fear or discomfort, usually lasting five to 30 minutes. Appropriate medications include benzodiazepines, tricyclic antidepressants and monoamine oxidase inhibitors. Alprazolam and clonazepam are quickly effective in alleviating panic, but they cause significant symptoms upon discontinuation. The best-studied drug in the treatment of panic disorder is imipramine; like other tricyclic antidepressants, it can cause increased jitteriness early in treatment. Monoamine oxidase inhibitors may be particularly helpful in patients with panic disorder who exhibit social avoidance. Behavior therapy, an important component of treatment, involves the patient's confrontation of fears or phobias.

Behavior Therapy↗
PubMed1992

An analysis of panel data. The impact of a psychiatric consultation letter on the expenditures and outcomes of care for patients with somatization disorder.

In this study, the cost and health outcomes of a psychiatric consultation letter to primary care physicians caring for a sample of patients diagnosed with somatization disorder, a psychiatric condition associated with multiple, unexplained medical complaints, was assessed. To accommodate the small sample size of 73 patients, outcome effects were calculated using panel analysis. Study patients were randomized to a consultation or noconsultation group, and were repeatedly assessed at equal time intervals. Data were analyzed using parsimonious regression models derived from economic theory. During the 1-year follow-up period, a psychiatric consultation letter was associated with a 12% reduction in health care costs ($455 per patient within first year), with no evidence of deterioration in physical, mental, or general health. Less powerful t-test comparisons between treated and control groups lead to different conclusions. Reasons for these differences are discussed.

Adult↗