Search PubMed⌕ Search

Biomedical subjects

T Lewis

Publications and source records attributed to T Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1990

Chorismate synthase. Pre-steady-state kinetics of phosphate release from 5-enolpyruvylshikimate 3-phosphate.

The pre-steady-state kinetics of phosphate formation from 5-enolpyruvylshikimate 3-phosphate catalysed by Escherichia coli chorismate synthase (EC 4.6.1.4) were studied by a rapid-acid-quench technique at 25 degrees C at pH 7.5. No pre-steady-state 'burst' or 'lag' phase was observed, showing that phosphate is released concomitant with the rate-limiting step of the enzyme. The implications of this result for the mechanism of action of chorismate synthase are discussed.

Binding Sites↗
PubMed1990

Percutaneous endoscopic gastrostomy: a two-year experience.

The results of percutaneous endoscopic gastrostomy in 25 patients who required enteral alimentation when feeding by mouth was not possible is reported. The procedure was successful on 30 occasions, with a low incidence of major complications. Endoscopic gastrostomy is a simple, less expensive alternative to surgical gastrostomy with a lower morbidity and mortality.

Adolescent↗
PubMed1990

The hospital ward sister: professional gatekeeper.

This study is a shortened report of research exploring ward sisters/charge nurses' perceptions of their responsibilities. (Throughout the study, the title 'ward sister' is used to refer to ward sister/charge nurse.) Using semi-structured interview technique, 10 hospital sisters from two large hospitals in the south of England were interviewed. The emergent data were analysed using grounded theory method. From the analysis, the substantive theory was developed that ward sisters act to gatekeep the professional function of the nurse. Many previous British studies have explored the role of the ward sister, reporting the powerful influence that the ward sister exerts over her environment. This study suggests that one of the reasons the ward sister is able to exert such power is because of her professional gatekeeper role. The shift in emphasis from the clinical to the managerial function of ward sister could therefore have important implications for the professional nursing function. Some possible implications are discussed and recommendations are made.

Employee Performance Appraisal↗
PubMed1990

The new revolving-door patients: results from a national cohort of first admissions.

A cohort of all first admissions to New Zealand psychiatric hospitals and psychiatric wards of general hospitals in 1980 and 1981 was followed up for 5 years. The cohort consisted of 3875 males and 3965 females aged from 15 to 64 years. Of these subjects, 59.4% had only one admission; 14.6% met our criteria for a revolving-door patient, as they had 4 or more admissions within the 5-year follow-up period. Based on first-admission information, patients who were younger and had a psychotic diagnosis had an increased likelihood of becoming a revolving-door patient. Stepwise logistic regression showed that younger age and psychotic diagnosis independently and in interaction were associated with a high probability of becoming a revolving-door patient. Although patients with a first-admission diagnosis of schizophrenia constitute a large group of the new revolving-door patients for both males and females, for women those with affective disorders and for men those with substance abuse comprise the largest proportion of the new revolving-door patients. This is because affective disorders in women and substance abuse in men are the most common diagnoses on first admission, rather than because the disorders themselves are associated with a high probability of the patients having multiple admissions.

Adolescent↗
PubMed1990

Distribution of pulmonary vascular resistance during lactic acid infusion in dogs.

We sought to determine the longitudinal distribution of pulmonary vascular resistance (PVR) in acute lactic acidosis utilizing pulmonary artery and vein balloon occlusion techniques (Holloway et al. J. Appl. Physiol. 54: 840-851, 1983). In anesthetized dogs, both a systemic vein (I-V) infusion and systemic artery (I-A) infusion of L-lactic acid were studied to control for potential effects of factors other than pH on PVR. During progressive I-A infusion (n = 9) to a pH of 6.94 +/- 0.06 there was no significant change in PVR or its distribution. In contrast, I-V infusion (n = 9) to a pH of 7.08 +/- 0.09 increased median PVR from 3.6 to 21.7 mmHg.1(-1).min (P less than 0.001), due to an increase in middle segment resistance (0.0-15.4 mmHg.1(-1).min, P less than 0.02). Examination by light and electron microscopy demonstrated pulmonary capillary obstruction with hemolyzed erythrocyte (RBC) membranes with I-V infusion, but representative I-A animals did not demonstrate these findings. Conceivably, the systemic vascular bed filtered the fragmented RBC membranes in the I-A model, but this microvascular obstruction with altered RBCs and RBC fragments caused the pulmonary hypertension observed in the I-V infusion. We conclude that lactic acidosis does not increase pulmonary vascular tone in dogs, a finding compatible with most previous studies in which observed increases in PVR may be attributed to other effects from I-V acid infusion on circulating blood elements.

Acidosis, Lactic↗
PubMed1990

Factors affecting patency of venous allografts in miniature swine.

In immunologically defined National Institutes of Health miniswine, a segment of internal jugular vein was anastomosed to the carotid artery as an interposition graft. Patency of swine major histocompatibility complex matched, one haplotype mismatched, and complete mismatched veins was 9.8, 6.3, and 3.0 weeks respectively (p = 0.009). More than 90% of mismatched and 20% of matched allografts developed a positive crossmatch before occlusion (p = 0.006). The mixed lymphocyte response did not predict graft occlusion. Treatment of 10 swine with cyclosporine (10 mg/kg/day) did not significantly improve patency for one haplotype mismatched grafts. In haplotype mismatched veins, cryopreserved grafts occluded more rapidly than noncryopreserved grafts: mean 2.4 versus 6.3 weeks, respectively (p = 0.002). In all cryopreserved vein grafts, alloantibody appeared at or after graft occlusion rather than before occlusion as seen with fresh allografts (p = 0.046). The mean patency of cryopreserved versus fresh autografts was 3.3 and greater than 32 weeks, respectively (p = 0.004). In summary, these results indicate that (1) allograft patency is related to the degree of swine major histocompatibility complex match and development of cytotoxic alloantibodies; (2) moderate-dose cyclosporine does not prolong allograft patency nor suppress development of antibody; (3) cryopreservation may accelerate graft occlusion through nonimmunologic mechanisms.

Animals↗
PubMed1989

Circulating erythropoietin in patients with myelodysplastic syndromes.

Serum concentration of erythropoietin (Epo) has been measured by radioimmunoassay in 46 patients with myelodysplastic syndromes. There is an overall inverse relationship between the level of Epo and the degree of anaemia but a wide range of Epo response between patients with similar haemoglobin concentrations. No differences were found between the different FAB groups, but the highest Epo levels were found in those patients with erythroid hypoplasia in the bone marrow. It is suggested that the intensity of erythroid activity in the marrow, as well as the degree of anaemia, may be a factor determining serum Epo concentration.

Adult↗
PubMed1988

Fluazifop, a grass-selective herbicide which inhibits acetyl-CoA carboxylase in sensitive plant species.

Fluazifop is a grass-selective herbicide that appears to act by inhibiting fatty acid synthesis de novo in sensitive species. Results from four different types of experiment show that this inhibition is due to an action of fluazifop on acetyl-CoA carboxylase and not on fatty acid synthetase. The acetyl-CoA carboxylase from sensitive barley (Hordeum vulgare), but not from resistant pea (Pisum sativum), is inhibited by the R stereoisomer, a finding that agrees with the herbicidal specificity of fluazifop.

Acetates↗
PubMed1988

Influence of parental knowledge and opinions on 12-month diphtheria, tetanus, and pertussis vaccination rates.

To assess the magnitude and cause of decreasing diphtheria, tetanus toxoids, and pertussis (DTP) immunization rates, a retrospective cohort study investigated the immunization status against pertussis among 1-year-old children in Utah. Questionnaires were sent to the parents of 2975 children born in June 1985. Parents were asked about each child's DTP immunization status, including the number, type, and dates of the vaccinations, reasons for or against vaccination, and their knowledge of whooping cough and the vaccine. Children were considered adequately immunized against pertussis when they had received three DTP vaccinations by their first birthday. In Utah, the lack of pertussis immunization among young children is a serious problem: greater than 30% of 1-year-old children were not adequately protected. Accurate parental knowledge about the relative risks of vaccination and illness was associated with a greater likelihood for immunization. Although some parents chose to forego the vaccination because they were concerned about its side effects, the most common reason for incomplete immunization was illness at the time the vaccination was to be given. If immunization rates are to improve, health care professionals must not only make an effort to educate the general population regarding the vaccine, but they must also ensure immediate follow-up for immunization when the procedure is delayed.

Attitude to Health↗
PubMed1988

Leaping the chasm between nursing theory and practice.

The author considers that whilst nurse tutors teach theory, nurse practitioners go on nursing in the same way that they always have done. There appears to be a chasm dividing theory and practice. This paper describes an attempt to leap that chasm. The paper identifies the problem, inherent in the nursing process that creates such difficulties in its implementation. The nursing process alone does not provide an adequate framework for nursing practice. The paper then describes how the translation of theory into practice took place on a ward in Brighton General Hospital, Brighton, England. The barrier between theory and practice is highlighted, along with a description of how the problems this presents to ward staff were overcome. The author considers that the attribution of cause is a key concept in the problem-solving approach, since it generates the question--Why?--and therefore that attribution of cause must be a concept in any model of nursing that is being used to implement the nursing process. The paper provides an example of how nursing models may be adapted, at ward level, to guide everyday practice, whilst retaining the conceptual framework of the model. The inference of the paper is that such a process could be applied to other models resulting in a greater use of theory in everyday nursing practice.

England↗
PubMed1987

A case of left atrial haemangioma: echocardiographic, surgical, and morphological features.

A slow growing encapsulated haemangioma of the left atrium was diagnosed by means of cross sectional echocardiography. The heterogeneous nature of the tumour was reflected in a central area of relative echolucency. After successful surgical removal of the tumour, the patient's symptoms of lethargy and limited exercise capacity improved considerably.

Echocardiography↗
PubMed1986

Effect of diesel emissions and coal dust inhalation on heart and pulmonary arteries of rats.

Fischer 344 (SPF) rats were exposed by inhalation to respirable particulate levels of 2 mg/m3 diesel emissions, diesel emissions plus coal dust, coal dust, or air for 7 h/d, 5 d/wk for 24 mo. The effects of treatment on body and heart weights, right and left ventricular wall thickness, severity of cardiomyopathy, and changes in the small pulmonary arteries were evaluated after 24 mo of exposure. In all dust-exposed animals, light microscopic examination of the lungs revealed dust-laden macrophages in alveolar spaces and focal accumulations of dust-laden macrophages near the respiratory bronchioles associated with hyperplasia of type II cells. This response was more prominent in animals exposed to diesel emissions alone. Age-related myocardial fibrosis and inflammatory infiltrates were common in all four groups. No statistically significant differences were detected between the groups for heart weights, ventricular wall thickness, and pulmonary arterial wall thickness. However, animals exposed to diesel emissions did show a consistent trend toward increased pulmonary arterial wall thickness, for all size categories of artery, compared to controls.

Animals↗
PubMed1986

Comparison of diflunisal and piroxicam in the management of patients with osteoarthritis.

An open-label comparison of diflunisal, a nonacetylated salicylate nonsteroidal anti-inflammatory drug (NSAID), and piroxicam, an NSAID belonging to the oxicam family, was conducted in patients with osteoarthritis. Efficacy assessments were made biweekly by the physician and patients during a 12-week treatment and observation period. The physician's evaluations showed that both drugs resulted in significant reductions in knee pain, tenderness, swelling, stiffness, and difficulty walking. A greater number of statistically significant differences were noted with diflunisal than with piroxicam, but there were no statistically significant differences between the two treatment groups. Patients' efficacy ratings tended to favor diflunisal, and diflunisal was significantly more effective than piroxicam in relieving night pain. Seventy-five percent of patients receiving diflunisal and 40% of those receiving piroxicam considered their condition improved after treatment; however, the proportion of good to excellent drug ratings was similar for the two drugs. Both drugs were generally well tolerated. Adverse effects were encountered in five (28%) of 18 patients given diflunisal and in four (33%) of 12 patients given piroxicam. Six patients were withdrawn from the study because of side effects, four from the piroxicam group and two from the diflunisal group. In this study, diflunisal was found to be an effective and well tolerated drug for use in the management of osteoarthritis.

Clinical Trials as Topic↗