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Biomedical subjects

D J Lewis

Publications and source records attributed to D J Lewis.

At least 19 recordsLinked to original sources
PubMed1992

Giardia lamblia as an intestinal pathogen.

Giardia lamblia are protozoan parasites which cause human intestinal disease. The life cycle has a multiplying intraduodenal trophozoite and an excreted cyst. Infection occurs after cyst ingestion from faecally contaminated water or by direct faecal-oral transmission in situations of poor sanitary standards, but the zoonotic nature of giardiasis is debated. The pathophysiology may arise from enzyme or active transport deficiencies, synergy with intestinal bacteria or an immunopathological process. Diagnosis is made by microscopic identification of cysts or trophozoites in small bowel samples or faeces. Symptoms are acute with diarrhoea (without blood), abdominal cramps, bloating and flatulence. The treatment of choice is either metronidazole or tinidazole. No vaccine or drug prophylaxis exists, and measures to avoid cyst ingestion should be undertaken.

Animals↗
PubMed1992

The Malaria Vaccine Epidemiology and Evaluation Project of Papua New Guinea: rationale and baseline studies.

The range of possible malaria vaccines, against different species of Plasmodium and various stages in the life cycle of the parasite in both human host and mosquito vector, is reviewed. The importance, in a malaria-endemic area, of protection by a malaria vaccine against disease rather than infection is emphasized, and the ways by which disease prevention may be achieved are discussed. Mechanisms of production and presentation of vaccines are considered, including the importance of appropriate and more effective adjuvants. The variety of immune responses to malaria is set out and linked to both human and plasmodial genetic factors. Host genetics may also modify susceptibility to malaria through mechanisms which are not immunological. There is a need for entomological studies of the Anopheles vectors, especially but not only in preparation for transmission-blocking vaccines. This overall complexity justifies a multidimensional approach to epidemiology and field-site preparation. An iterative procedure is proposed for initial field evaluation, through adult male volunteers to community studies in immune adults and then to semi-immune school children, before evaluation in the principal target population of nonimmune young children. The outcome variables for epidemiological evaluation are specified. After this brief review of malaria vaccines, the baseline studies being undertaken by the Malaria Vaccine Epidemiology and Evaluation Project of the Papua New Guinea Institute of Medical Research in the Wosera area of East Sepik Province are discussed in some detail, and their rationale linked to the range and complexity of the malaria vaccines that have been reviewed. These studies are described under the headings of their principal components of epidemiology, parasitology, immunology, genetics and entomology.

Animals↗
PubMed1992

ICU nurses' coping measures: response to work-related stressors.

Stress is an integral part of every workplace. The environment of an intensive care unit exposes critical care nurses to a proportionately greater amount of work-related stress than most occupations. Several components contributing to stress as well as coping measures are discussed in this article.

Adaptation, Psychological↗
PubMed1992

Balancing quality of care and cost-effectiveness through case management.

The changing climate within the health care system has necessitated the exploration of innovative strategies to provide quality-based cost-effective care. At a time when cost, quality, and efficiency are key issues, communication and coordination are crucial. Through a deliberate, collaborative approach to goal-directed care, case management facilitates the linking of quality and cost-effective care.

Adult↗
PubMed1991

The early cellular and humoral immune response to primary and booster oral immunization with cholera toxin B subunit.

The immune response to cholera toxin B subunit given orally was studied in 13 human volunteers. A serum IgG and IgA antitoxin response was observed, which was boosted by a second immunization. Using an immunospot assay, cells spontaneously secreting anti-toxin IgG and IgA, but not IgM appeared transiently in the blood after immunization. There were 105 IgG- and 87 IgA-secreting cells per 2 x 10(6) mononuclear cells 7 days after the first immunization, and 282 IgG- and 413 IgA-secreting cells 5 days after the second immunization. A polyclonal increase in total IgM-secreting cells was observed. Few anti-toxin-secreting cells were observed in the bone marrow at the peak of the circulating cell response, which could be accounted for by contamination of the sample with peripheral blood, suggesting that the bone marrow is not a significant site of anti-toxin-secreting cells after oral immunization.

Administration, Oral↗
PubMed1991

Morphological assessment of pathological changes within the rat larynx.

Routine histological examination of the rat larynx, from inhalation toxicity and carcinogenicity studies, has been routinely performed in this laboratory for over 15 yr. This work has identified the larynx as an important target organ with a number of pharmaceuticals, industrial chemicals, agricultural chemicals, and environmental pollutants. The rat larynx contains 5 epithelial types: stratified squamous; low squamoid; respiratory; and 2 forms of pseudostratified cuboidal epithelium. Each epithelial type has a specific location within the relatively complex anatomical configuration of the larynx. The detection of induced changes requires a consistent, thorough and detailed histological examination in order to identify the often subtle changes in the distribution of these epithelial types. Induced lesions show distinct predilection sites, including the ventro-lateral regions anterior to the ventral pouch and the inner aspects of the arytenoid projections. Lesions commonly involve degeneration of the original epithelial cells with subsequent regeneration; hyperplasia and squamous metaplasia. In more severe reactions, the larynx may illustrate epithelial ulceration with exudation. To some extent the changes commonly observed are dependent upon the duration of the study and the dose level employed, rather than the individual compound. Recovery or regression of induced changes is variable and dependent upon the time scale involved and severity or type of initial lesion.

Animals↗
PubMed1991

Stress management: a program designed to facilitate coping.

1. Continual exposure to work-related stressors compounds nurses' workloads, increases their stress levels, and places increased demands on their abilities to adapt. 2. Nurses need to learn and routinely use coping measures to prevent exhaustion and burnout. 3. An in-house stress management program can help nurses learn to cope with constant exposure to work-related stressors, halt the cyclic process of stress, prevent burnout, and decrease turnover.

Adaptation, Psychological↗
PubMed1991

Impact of the entomophilic digenean Plagiorchis noblei (Trematoda: Plagiorchiidae) on the survival of Aedes provocans under field conditions.

Under field conditions, exposure of Aedes provocans to Plagiorchis noblei cercariae reduced the number of pupae produced to about one-third of control values. Larvae bearing more than 2 metacercariae rarely survived, and pupal mortality was almost 3 times higher among exposed individuals than controls. Adult females exposed to cercariae as pre-imagos experienced a 32% reduction in longevity. The life span of males was not affected. The potential of entomophilic digeneans as biological agents in the control of mosquitoes is discussed.

Aedes↗
PubMed1990

Dialysis and renal transplantation in children: long term and recent experience.

The outcome of 38 children with endstage renal failure who entered a dialysis and renal transplant programme over a period of 16 years is reported. The initial care was given in an adult programme but in 1985 this was changed to a comprehensive and specifically paediatric programme. Patient survival was 97, 86 and 80% at 1, 5 and 10 years respectively. Thirty-four of the patients spent a mean period of 19 months (range 1-160 months) on dialysis with the preferred form of dialytic therapy being continuous ambulatory peritoneal dialysis. Primary cadaveric graft survival was 72 and 42% at 1 and 3 years respectively; although since 1985 1 year graft survival has risen to 90%. The major long term problems have been growth failure and poor social development. Eighty-seven per cent of children have been able to continue normal schooling, and of the 18 who have left school 14 (78%) are employed or undertaking tertiary education. Thus dialysis and transplantation has allowed not only excellent patient survival but also the achievement of satisfactory educational standards and subsequent employment for the majority of patients.

Adolescent↗
PubMed1990

Continuing education in gerontological nursing.

Programs are needed to evaluate staff because more elderly with multiple health-care problems are being hospitalized. Current formal training programs do not always have gerontology content based on up-to-date standards. Stimulation exercises give healthy young and middle-aged health-care workers an idea of challenges confronting the elderly with loss of mobility, vision, hearing, or paralysis. A survey of staff nurses indicated that most had difficulty differentiating physical and psychosocial changes attributed to the normal aging process from pathological manifestation. Awareness of the biological, developmental, and psychosocial theories of aging provide health-care workers a greater understanding of rationale for a specific treatment program.

Aged↗
PubMed1990

Spice of life: a strategy to enhance dietary compliance.

A creative teaching strategy was implemented to stimulate patients' motivation to incorporate learned dietary concepts into their daily life-style. Thirty-five hemodialysis patients were given a pamphlet that described herbs and spices to enhance the flavor of specific foods and 25 sample seasoning packets for their experimentation. Most stated that the pamphlet was helpful (82.9%) and use of the spices made the diet palatable 75% or more of the time (93.4%).

Condiments↗
PubMed1990

Games: a way to give laboratory values meaning.

Through the use of gaming techniques patients may acquire a better understanding of the significance of serum laboratory values and their relationships to the disease process and treatment regimen. Games provide practitioners with an alternative teaching strategy that may be used to reinforce learning and positively change health beliefs and behaviors that will ultimately promote compliance with the treatment regimen.

Game Theory↗
PubMed1989

The effects of host distributional patterns on parasite transmission: Aedes aegypti larvae and Plagiorchis noblei Cercariae.

The effects of distributional patterns of the host on the acquisition of Plagiorchis noblei cercariae by Aedes aegypti larvae were determined. Mosquito larvae that were allowed to disperse were more susceptible to infection than confined larvae. Because these mosquito larvae are known to aggregate in light and disperse in darkness, they are more likely to acquire P. noblei infections at night. The timing of cercarial emergence in relation to the distributional patterns of the mosquito host is discussed.

Aedes↗
PubMed1988

Studies on the mechanism by which tryptophan efflux from isolated synaptosomes is stimulated by depolarization.

1. The efflux and influx of tryptophan across the synaptosomal plasma membrane has been studied under a variety of experimental conditions, in order to examine the mechanism by which depolarization enhances the efflux of tryptophan from superfused synaptosomes. 2. Efflux of [3H]-tryptophan from preloaded superfused synaptosomes was found to be enhanced by K+ depolarization in a Ca2+ and dose-dependent manner. In contrast, [3H]-phenylalanine efflux was only poorly stimulated by depolarization and only by very high concentrations of K+. 3. Tryptophan efflux was also enhanced by decreasing the extracellular Na+ concentration, but this effect was not dependent on extracellular Ca2+. 4. Influx of [3H]-tryptophan into synaptosomes was stimulated by extracellular Na+ removal, but the uptake of [3H]-phenylalanine was unaffected by this procedure. 5. Both the induced influx and efflux of tryptophan observed under these experimental conditions was inhibited by immobilizing the plasma membrane carrier with parachlorophenylalanine. This implied that both the enhanced influx and efflux arose as a consequence of the activation of the membrane tryptophan carrier, the direction of the observed effect being dependent upon the manner in which the experiments were conducted. 6. The relationship between depolarization, the activation of the membrane tryptophan carrier and the significance of this to the in vivo situation is discussed.

Animals↗