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Biomedical subjects

D R Lewis

Publications and source records attributed to D R Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1998

The progression and correction of duplex detected velocity shifts in angiographically normal vein grafts.

OBJECTIVES: To review the sensitivity of duplex scanning and angiography at detecting vein graft stenoses in patients on a graft surveillance programme. DESIGN: Prospective, open, non-randomised study. PATIENTS AND METHODS: Since February 1993, 143 patients with 148 grafts (70% in situ, 30% reversed) have attended postoperative infrainguinal vein graft surveillance for a minimum of 6 weeks. Fifty-seven graft stenoses in 57 grafts were identified by duplex scanning as a localised high velocity jet. Angiography was performed in all except 12 patients. RESULTS: Angiography confirmed a duplex abnormality in all but 10 patients. Of these, five patients remain stable and asymptomatic with a persisting duplex abnormality. The remaining five patients, although asymptomatic, exhibited disease progression on duplex and surgical intervention confirmed significant stenoses, which were successfully treated. CONCLUSION: The results suggest that duplex scanning is a reliable imaging modality for detecting vein graft stenoses. Selection for surgical correction can be made, in some circumstances on the basis of clinical and ultrasound criteria alone.

Adult↗
PubMed1997

Antidepressant-like effect of brain-derived neurotrophic factor (BDNF).

Previous studies have shown that infusion of brain-derived neurotrophic factor (BDNF) into the midbrain, near the PAG and dorsal/median raphe nuclei, produced analgesia and increased activity in monoaminergic systems. Alterations in monoaminergic activity have also been implicated in the pathogenesis and treatment of depression. The present studies examined the ability of centrally administered BDNF to produce antidepressant-like activity in two animal models of depression, learned helplessness following exposure to inescapable shock and the forced swim test. In the learned helplessness paradigm, vehicle-infused rats pre-exposed to inescapable shock (veh/shock) showed severe impairments in escape behavior during subsequent conditioned avoidance trials, including a 47% decrease in the number of escapes and a 5 fold increase in escape latency, as compared to vehicle-infused rats which received no pre-shock treatment (veh/no shock). Midbrain BDNF infusion (12-24 micrograms/day) reversed these deficits, and in fact, BDNF-infused rats pre-exposed to inescapable shock (BDNF/shock) showed escape latencies similar to veh/no shock and BDNF/no shock rats. In the forced swim test, BDNF infusion decreased the immobility time by 70% as compared to vehicle-infused controls. Non-specific increases in activity could not account for these effects since general locomotor activity of BDNF- and vehicle-infused animals was not different. These findings demonstrate an antidepressant-like property of BDNF in two animal models of depression, which may be mediated by increased activity in monoaminergic systems.

Animals↗
PubMed1997

Computerised audit of carotid endarterectomy: audit loopholes closed?

The number of carotid endarterectomies being performed in the UK is increasing. The role of carotid endarterectomy (CEA) in the prevention of stroke depends on the procedure being associated with as few operative strokes as possible. Good clinical practice, with minimum morbidity, depends upon the integration of recent advances. Continuing audit has been used to examine changes in surgical practice and in case mix. There was a combined death and permanent stroke rate of 3.6% after 333 CEAs in a 6-year period (1990-1995) compared with 4.4% in 203 CEAs in an earlier 5-year audit period (1985-1989). The impact of an increase in the number of operations performed after recovered strokes, those performed by trainees and the use of prosthetic patches on the results of CEA has been assessed. Specific areas to be targeted in future audits are identified.

Adult↗
PubMed1995

Time course for entry of intestinally infused lipids into blood of rats.

The early time course of the absorption of duodenally infused 14C-labeled Intralipid into either the hepatic portal circulation or systemic circulation was measured. Plasma radioactivity did not increase significantly at either site until 30 min after the intestinal infusion began and was maximal between 60 and 120 min. In studies on the effects of intestinal lipid infusions on sham feeding in rats we find significant suppressions of sham feeding after only 10 min. Thus the time course for lipid absorption is different from that of the satiating effects of duodenally infused fats. These results are consistent with the hypothesis that the satiating effect of fats infused into the small intestine occurs before entry of absorbed fats into the blood and is not dependent on recently absorbed circulating fat.

Animals↗
PubMed1994

Multiple myeloma among blacks and whites in the United States: the role of chronic antigenic stimulation.

Multiple myeloma (MM) is twice as common among Blacks than Whites in the United States. The reasons for this racial disparity are unknown, and the etiology of this cancer, in general, is poorly understood. Repeated or chronic antigenic stimulation (CAS) of the immune system has been suggested as a risk factor. Previous case-control studies have reported inconsistent CAS associations based on evaluations of individual and biologic categories of medical conditions. Interview data from 573 cases and 2,131 population-based controls were used to investigate further the CAS hypothesis using an immunologically based approach, and to determine whether CAS accounts for the excess of myeloma among Blacks. Over 50 medical conditions were grouped into biologically and immunologically related categories, and B-cell- and T-cell-mediated response groups. Except for urinary tract infections among Black men (odds ratio [OR] = 2.0), no significantly increased risks of MM were observed. However, there was a suggestion of increased risk among Blacks with an increased exposure to anaphylactic conditions. Analysis by immunoglobulin type revealed significantly elevated risks of IgG myeloma with eczema (OR = 2.1), the biologic category 'allergic conditions' (OR = 1.6), and the immunologic category 'anaphylaxis response' (OR = 1.6) among Whites, with Blacks having slightly lower risks. Our findings do not support a causal relationship between CAS and MM, nor do they explain the higher incidence among Blacks.

Adult↗
PubMed1994

Infection in immunocompromised patients with malignant blood disorders in a district general hospital.

The pattern and management of infection in immunocompromised patients over a period of 3 years in a district general hospital has been studied. A total of 222 positive cultures was obtained in 607 episodes of suspected infection all involving patients with malignant blood disorders. Febrile episodes requiring intravenous antibiotics occurred in 248 instances involving 107 patients. The pattern of organisms cultured and the responses to various antibiotic regimes are reported. The costs of antibiotic therapy are considered in the light of the overall response. Of the patients studied, 54 died, infection having a likely causative or contributory part in 21 of them (less than 10% of infective episodes). We conclude that the infective complications of these disorders, particularly in older patients, can be efficiently managed in a district general hospital when full supportive facilities are available.

Adult↗
PubMed1994

Inclusion of women and minorities in occupational cancer epidemiologic research.

A survey of published epidemiologic studies from eight journals during 1971 to 1990 was conducted to assess the proportion and characteristics of occupational cancer studies that have included women and minorities. A total of 1233 reports included 562 (46%) with subjects limited to white men. The remaining 671 (54%) had subjects from other race-gender groups. Thirty-five percent included white women, but only 14% presented any analyses of white women specifically and only 7% presented more than five risk estimates. The proportions with analyses of nonwhite women (any = 2%; detailed = 1%) or men (any = 7%; detailed = 3%) were also small. Studies with detailed analyses of women and minorities tended to use weaker methodologies (ie, proportionate mortality or cross-sectional design) than the studies of white men and were less able to provide convincing data on the occupational cancer risks of women and minorities.

Epidemiologic Methods↗
PubMed1992

Empirical analysis of multidimensional measures of community adjustment for young adults with mental retardation.

Confirmatory factor analysis procedures were used to evaluate multidimensional measures of community adjustment in a sample of 239 young adults with mild to severe mental retardation. Alternative measurement models were evaluated in one-half of the sample, with the final model cross-validated in the second half of the sample. The final cross-validated model was also evaluated as a function of level of retardation. Evidence was found for at least six broad dimensions of community adjustment when combined with other multidimensional research findings. The measurement of one dimension varied as a function of degree of retardation. Use of validated multidimensional measures of community adjustment in future research studies was discussed.

Activities of Daily Living↗
PubMed1991

Efficiency considerations in delivering special education services to persons with severe mental retardation.

The basic question addressed in this paper is whether formal benefit-cost and effectiveness-cost analyses might allow us to determine whether the outcomes of particular special education services are being offered in their most efficient manner. In attempting to answer this question, we focused upon measuring as many of the cost and outcomes as possible (in both monetary and other terms) from two specialized schools serving youth with severe mental retardation. We examined a number of alternative assumptions for illustrating some of the problematic issues in the use of such evaluation techniques.

Adolescent↗
PubMed1985

Computerized axial tomography versus complex motion as a predictor of surgical findings in middle ear and mastoid cholesteatoma.

In order to evaluate the efficacy of polytomography and computerized tomography in the prediction of surgical findings in cases of suspected cholesteatoma of the middle ear and mastoid, we evaluated preoperatively 52 ears by both radiographic methods. We utilized a check list of 14 radiological signs or surgical findings to generate measures of sensitivity and specificity. The strengths of each radiographic method are outlined and the considerable weaknesses in predictive value are discussed.

Cholesteatoma↗
PubMed1984

Alcohol and the gastrointestinal tract.

The effects of acute and chronic ethanol ingestion on esophageal motility and the potential complications of these alterations are reviewed. Injury to the gastric mucosa and the small intestine and alterations in intestinal absorption can also result from alcohol abuse.

Alcoholic Intoxication↗