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Biomedical subjects

R Lewis

Publications and source records attributed to R Lewis.

At least 19 recordsLinked to original sources
PubMed2001

Timely detection of meningococcal meningitis epidemics in Africa.

BACKGROUND: Epidemics of meningococcal disease in Africa are commonly detected too late to prevent many cases. We assessed weekly meningitis incidence as a tool to detect epidemics in time to implement mass vaccination. METHODS: Meningitis incidence for 41 subdistricts in Mali was determined from cases recorded in health centres (1989-98) and from surveillance data (1996-98). For incidence thresholds of 5 to 20 cases per 100000 inhabitants per week, we calculated sensitivity and specificity for detecting epidemics, and determined the time lapse between threshold and epidemic peak. FINDINGS: We recorded 9084 meningitis cases. Clinic-based weekly incidence of 5 and 10 cases per 100000 inhabitants detected all meningitis epidemics (sensitivity 100%, 95% CI 93-100), with median threshold-to-peak time of 5 and 3 weeks. Under-reporting reduced sensitivity: only surveillance thresholds of 5 or 7 cases per 100000 inhabitants per week detected all epidemics. Crossing the lower threshold before the 10th calendar week doubled epidemic risk relative to crossing it later (relative risk 2.1, 95% CI 1.4-3.2). At 10 cases per 100000 inhabitants per week, specificity for outbreak prediction was 88%, 95% CI 83-91). For populations under 30000, 3 to 5 cases in one or two weeks predicted epidemics with 85% to 97% specificity. INTERPRETATION: Low meningitis thresholds improve timely detection of epidemics. Ten cases per 100000 inhabitants per week in one area confirm epidemic activity in a region, with few false alarms. An alert threshold of 5 cases per 100000 inhabitants per week allows time to investigate, prepare for an epidemic, and initiate mass vaccination where appropriate. For populations under 30000, the alert threshold is two cases in a week. High quality surveillance is essential.

Disease Outbreaks↗
PubMed2001

Opium past, opioid futures: imperialism, insurgency and pacification in a global commodity market.

This is a lightly edited version of Roger Lewis' notes for the speech he gave at the 11th International Conference on the Reduction of Drug Related Harm in Jersey in March 2000, shortly before his death. In this paper Roger Lewis argues for the need to take global and historical view of both drug markets and ways that nations try to control them. Drug markets have become globalised, influenced by changes in communication, finance, commodity and labour markets. Drug control activities are used to defend global strategic interests, amd foreign policy imperatives usually take precendence over drug policy.

Journal Article↗
PubMed2001

Extreme diversity, conservation, and convergence of spider silk fibroin sequences.

Spiders (Araneae) spin high-performance silks from liquid fibroin proteins. Fibroin sequences from basal spider lineages reveal mosaics of amino acid motifs that differ radically from previously described spider silk sequences. The silk fibers of Araneae are constructed from many protein designs. Yet, the repetitive sequences of fibroins from orb-weaving spiders have been maintained, presumably by stabilizing selection, over 125 million years of evolutionary history. The retention of these conserved motifs since the Mesozoic and their convergent evolution in other structural superproteins imply that these sequences are central to understanding the exceptional mechanical properties of orb weaver silks.

Amino Acid Motifs↗
PubMed2001

Patient and partner satisfaction with Viagra (sildenafil citrate) treatment as determined by the Erectile Dysfunction Inventory of Treatment Satisfaction Questionnaire.

OBJECTIVES: To assess the efficacy and safety of Viagra (sildenafil citrate) in male outpatients with erectile dysfunction and patient and partner satisfaction with treatment using the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS). METHODS: A total of 247 patients with erectile dysfunction of broad-spectrum etiology were treated in a randomized, double-blind, parallel-group, multicenter study conducted at outpatient clinics. Patients receiving oral sildenafil (25, 50, and 100 mg) were compared with patients receiving placebo during a 12-week period. The principal efficacy measures were responses to question 3 (ability to achieve an erection) and question 4 (ability to maintain an erection) on the International Index of Erectile Function and three global efficacy questions. Patient and partner satisfaction with treatment were assessed, for the first time, using the EDITS questionnaire. RESULTS: Efficacy scores for the International Index of Erectile Function questions and the global efficacy questions were significantly higher for patients receiving sildenafil than for those receiving placebo (P <0.001). Both patients and partners receiving sildenafil also had significantly higher EDITS scores than those receiving placebo (P <0.001). Adverse events were chiefly mild or moderate. Two patients receiving sildenafil and none receiving placebo discontinued treatment because of adverse events. CONCLUSIONS: Sildenafil was an effective, well-tolerated treatment for erectile dysfunction in an outpatient setting. Partner evaluations corroborated patient assessments. The results from the EDITS questionnaire indicated that after 12 weeks of receiving sildenafil both patients and partners reported higher levels of treatment satisfaction relative to placebo.

Adult↗
PubMed2001

Predicting survival in an elderly burn patient population.

The purpose of this study was to analyze the outcome of elderly burn victims and to determine an instrument to predict survival in this population. Charts of three hundred and eight burn patients > or =60 yr of age who were admitted to a university-based hospital between the years of 1977-1996 were retrospectively analyzed. The mean age of the population was 71.5+/-8.6, with a male predominance (1.8 to 1, P < 0.001). The majority of the burns were secondary to flame injuries (210, 68.6%). The median body surface area (BSAB) was 13.0% with an in-hospital mortality rate of 30.2%. We demonstrated improved survival in patients aged 60-74 yr as compared to 1965-1971 national burn survival data. A similar trend could not be shown in the very old (> 75 yr of age). Only age and BSAB were related to death by multiple stepwise forward linear regression. The Baux score, which adds age and BSAB, was predictive of outcome in 87.0% of our population. In conclusion, this study reinforces the high mortality associated with burn injuries in the elderly and the superior ability of the Baux score (age + percent burn) in predicting outcome in this population.

Age Factors↗
PubMed2001

Erection and NO override the vasoconstrictive effect of alpha-adrenergic stimulation in the rat penile vasculature.

Studies in this laboratory are designed to determine the effects of vasoconstrictor agents on the erectile response in rats. We have previously demonstrated that the vasoconstrictor effect of endothelin-1 (ET-1) is sharply reduced by erection and by nitric oxide (NO) administration. The present study was performed to determine if vasoconstriction, resulting from alpha-adrenergic stimulation, is altered by erection and NO. During continuous monitoring of corpus cavernosum pressure (CCP) and mean arterial pressure (MAP), erection was induced by electrical stimulation of the autonomic ganglion for the innervation of the penis. When the alpha-adrenergic agonist methoxamine (METH, 10 microg/kg) was injected before erection (ie, into the non-erect penis), the subsequent erectile response (CCP/MAP) was significantly reduced from 0.68+/-0.03 before METH to 0.34+/-0.08 after METH. Injection of METH into the erect penis (ie, during erection) reduced the vasoconstrictor action of METH; CCP/MAP was 0.74+/-0.02 before METH and 0.55+/-0.05 after METH (P<0.05). The vasoconstrictor action of METH was slightly reduced when given in conjunction with NOR-1, a NO donor drug; CCP/MAP was 0.70+/-0.05 before METH, 0.55+/-0.09 after METH but this change was not significant. These results demonstrate that the response to alpha-adrenergic stimulation is attenuated during erection in response to ganglionic stimulation. Furthermore, it appears that NO, produced during erection, may serve to override agonist-induced vasoconstriction. These results support our hypothesis that NO acts to directly stimulate relaxation of cavernous smooth muscle and to inhibit the vasoconstrictor actions of agents like ET-1 and alpha-adrenergic agonists including norepinephrine.

Adrenergic alpha-Agonists↗
PubMed2001

Substance use and unsafe sex amongst homosexual men in Edinburgh.

A self-reported behaviour survey using an anonymous critical incident based questionnaire was administered by trained interviewers in 1998. Five hundred and thirty-one homosexual and bisexual men were recruited from gay bars, clubs, cafes, a sauna and 'cruising ground' in central Edinburgh. The use of alcohol and recreational drugs and details of sexual activity over the preceding three months and at the last sexual encounter were recorded. Unsafe sex was defined as anal sex without the use of a condom with a partner of unknown or different HIV status. Safer sex was defined as all other types of sex, including anal sex with a condom and anal sex without a condom with a partner whose HIV status was known to be the same. Of the questionnaires completed, 506 were suitable for analysis; 29 men (6.1%) reported anal sex with a partner of unknown or different HIV status without a condom ('unsafe sex') during their last sexual encounter. A total of 53 men (10.5%) could recall an episode of unsafe sex within the last three months. Men who had used marijuana or inhaled nitrites ('poppers') less than two hours before sex, or whose sexual partners had done so, were more likely to have unsafe sex than those who had not. Although alcohol use was more likely before sex with casual partners, the use of alcohol less than 2 hours before sex was not associated with sex being unsafe.

Adolescent↗
PubMed2001

Use of rank-order analysis of ordinal exposure data: application to vinyl chloride exposure.

The University of Louisville currently maintains a database of work histories and exposure rankings for chemicals used in the production of polyvinyl chloride from the plant where the original angiosarcoma cases were identified. A 6-point ranking scale was used to characterize worker exposure to vinyl chloride by year, building, and job. Since this is ordinal data, non-parametric statistics have been used to evaluate exposure factors in case-control studies. Rank order analysis of vinyl chloride exposure and angiosarcoma shows a strong statistical association. In contrast, the method shows no association between vinyl chloride exposure and brain cancer. Exposure ranking is a reasonable alternative to estimation of actual dose. Rank order analysis allows for a rapid assessment of exposure-disease associations for case control studies.

Brain Neoplasms↗
PubMed2001

Angular malalignment after intramedullary nailing of femoral shaft fractures.

OBJECTIVES: To determine factors associated with angular malalignment of femoral shaft fractures treated with intramedullary nails and to determine differences in the incidence of angular malalignment based on fracture location, fracture comminution, and method of treatment (i.e., antegrade or retrograde). DESIGN: Retrospective. SETTING: Level I trauma center. PATIENTS: Three hundred sixty patients with 374 femoral shaft fractures were identified from a prospectively obtained orthopaedic trauma database. Complete sets of immediate postoperative anteroposterior and lateral radiographs were available for 355 (95 percent) of the 374 fractures. INTERVENTION: Patients were treated with antegrade (183 cases) or retrograde (174 cases) intramedullary femoral nailing. MAIN OUTCOME MEASURE: Goniometric measurements were made on all immediate postoperative radiographs to determine the coronal plane and sagittal plane angular alignments. A multiple linear regression statistical analysis was used to determine factors associated with increasing angular malalignment. The incidence of malalignment was determined using more than 5 degrees of deformity in any plane as the definition of malalignment. RESULTS: Proximal fracture location, distal fracture location, and unstable fracture pattern were associated with increasing fracture angulation (p < 0.001). Fracture location in the middle third, stable fracture pattern, method of treatment (i.e., antegrade or retrograde), and nail diameter were not associated with increasing fracture angulation (p > 0.05). The incidence of malalignment was 9 percent for the entire group of patients, 30 percent when the fracture was of the proximal third of the femoral shaft, 2 percent when the fracture was of the middle third, and 10 percent when the fracture was of the distal third. The incidence of malreduction was 7 percent for patients with stable fracture patterns and 12 percent for those with unstable fracture patterns. CONCLUSIONS: Patients with fractures of the proximal third of the femoral shaft treated with intramedullary nails are at highest risk for malalignment. Proximal fracture location, distal fracture location, and unstable fracture pattern are associated with increasing fracture angulation.

Adolescent↗
PubMed2001

Venous thromboembolism after acute stroke.

BACKGROUND: Treatment for venous thromboembolism (VTE) is highly effective in preventing morbidity and mortality, yet pulmonary embolism (PE) accounts for up to 25% of early deaths after stroke. This is because the current diagnostic paradigm is reactive rather than proactive: the clinician responds to VTE when it becomes symptomatic, in the expectation that initiation of treatment will prevent progression to more serious manifestations. This approach is flawed, because sudden death from PE is frequently unheralded and nonfatal symptomatic pulmonary emboli are often unrecognized or misdiagnosed. SUMMARY OF COMMENT: Morbidity and mortality from PE could be reduced either by more effective thromboprophylaxis or earlier diagnosis and treatment of established VTE. The fact that early use of short-term, low-dose, unfractionated heparin (UFH) is not associated with sustained, clinically meaningful benefit suggests that a fundamental change in the diagnostic approach to VTE is needed, one which requires a greater appreciation that clinically apparent events are merely the tip of the thromboembolism iceberg. CONCLUSIONS: Research into a strategy of screening for subclinical VTE in these patients is needed, with a view to identifying a subgroup at risk of progression to symptomatic and life-threatening events, in whom outcome might be improved by anticoagulation.

Anticoagulants↗
PubMed2001

The national health service plan: further reform of British health care?

Less than three years after initiating a series of health service reforms, the Blair government has launched another plan for the U.K. National Health Service. This article considers the origins and contents of the plan. A major investment program is designed to bring health care spending up to European averages over the next five years. In return, the government seeks to challenge the existing settlement between organized medicine and the state through tighter regulatory control, altered contractual frameworks, and a new public-private concordat. The plan does not represent a radical change in government policy but rather reaffirms existing approaches to increasing access to health services, integrating health and social care, and empowering users. Notwithstanding arrangements to increase the autonomy of health service organizations, the plan increases central control through a range of new bodies and regulatory frameworks. It represents an incremental adjustment of the existing tax-funded system. Should this reinvigoration of the state monopoly fail, alternative sources of funding will no doubt have to be reconsidered.

Comprehensive Health Care↗
PubMed2001

A rapid and systematic review of the clinical effectiveness and cost-effectiveness of debriding agents in treating surgical wounds healing by secondary intention.

BACKGROUND: Most surgically sutured wounds heal without any complication. However, in some cases wound healing can be delayed due to the presence of infection or wound breakdown. This can result in the wounds becoming cavity wounds and thus necessitate healing by secondary intention. Other surgical wounds that are not sutured but left to heal by secondary intention include abscess cavities such as perianal abscesses or breast abscesses. Surgical wounds healing by secondary intention are thought to heal more slowly than wounds healing by primary intention, especially if infection is present or healing is compromised by factors such as decreased blood supply, poor nutritional status or a general suppression of the immune response. Such wounds may contain dead tissue and have a moderate or high level of exudate. Debridement involves the removal of devitalised, necrotic tissue or fibrin from a wound. There are many different methods that can be used to debride a wound, which are broadly classified as surgical/sharp, biosurgical, mechanical, chemical, enzymatic and autolytic. Although it is generally agreed that the management of surgical wounds which contain devitalised tissue and are healing by secondary intention requires debridement, it is not always clear as to what is the best method or agent to use. There is currently a large selection of products with debriding properties available on the market, which vary considerably in cost. It is important that the choice of both debriding method and product is based on the best scientific evidence available, taking into account both cost and effectiveness data. OBJECTIVES: The review had two main objectives: (1) To determine the clinical effectiveness and cost-effectiveness of debriding agents in treating surgical wounds healing by secondary intention. (2) To evaluate the clinical effectiveness and cost-effectiveness of treating patients with surgical wounds healing by secondary intention at specialised wound care clinics as compared to conventional care. The review incorporated all debriding methods and any agent that is considered to have a debriding property. METHODS The following databases were searched using strategies designed specifically for each database: MEDLINE, EMBASE, CINAHL, HMIC (Health Management Information Consortium), CCTR via the Cochrane Library, the National Research Register (NRR), the NHS Economic Evaluation Database (NHS EED), and the Health Economic Evaluations Database (HEED). Additional references were identified through reviewing manufacturer and sponsor submissions made to NICE, the bibliographies of retrieved articles, and conferences proceedings on the Internet. Only randomised controlled trials (RCTs) or non-randomised controlled trials with concurrent controls and full economic evaluations were considered for inclusion. Only studies that evaluated some sort of debriding method or a specialised wound care clinic (a nurse with specialist training in wound care; care being provided by a multidisciplinary team; a fast-track referral system to other professions (e.g. dermatologist); or access to the latest health technology) were included in the review. Studies had to include participants with surgical wounds healing by secondary intention (e.g. cavity wounds, the consequences of wound dehiscence and abscesses) and report an objective measure of wound healing. Data were extracted by one reviewer and checked by a second. Quality assessment was conducted independently by two reviewers. Disagreements were resolved by consensus and, when necessary, by recourse to a third reviewer. The primary outcomes of interest were wound healing and cost. Results of data extraction and quality assessment were presented in structured tables and also as a narrative summary. In addition, where feasible, the results of individual studies were presented as forest plots. Studies were grouped according to the type of wound, debriding method and outcome measure used. RESULTS - CLINICAL EFFECTIVENESS: Seventeen trials met the inclusion criteria, all of which used the autolytic method of debridement. No studies were found that investigated sharp/surgical, biosurgical, mechanical, chemical or enzymatic debridement in the treatment of surgical wounds healing by secondary intention. No studies were found which investigated specialised wound care clinics that included the provision of care within a clinical setting (based in either primary or secondary care). The type of surgical wounds investigated by studies included in the review were those that had broken down postoperatively, perineal wounds resulting from proctolectomy or rectal excision, and those left open after pilonidal sinus excision or abscess incision, or wounds following a laparotomy. Four additional studies investigated treatment of postoperative wounds from toenail avulsions. (ABSTRACT TRUNCATED)

Clinical Trials as Topic↗
PubMed2000

A voxel-by-voxel analysis of [18F]setoperone PET data shows no substantial serotonin 5-HT(2A) receptor changes in schizophrenia.

Several postmortem studies have reported regionally localized decreases in serotonin(2A) receptors (5-HT(2A)R) in schizophrenia. This was not confirmed by two recent [18F]setoperone positron emission tomography (PET) studies. In these two studies relatively large regions of interest (ROIs) were used; hence, 5-HT(2A)R changes may have been missed in some brain areas. Therefore, data from one study were analyzed on a voxel-by-voxel basis using Statistical Parametric Mapping (SPM). We also used this method to examine the relationship between 5-HT(2A)R binding potential (BP) and five PANSS-derived factors: negative, positive, activation, dysphoric and autistic preoccupation. Thirteen schizophrenic patients (10 antipsychotic-naïve, 3 antipsychotic-free; 11 M, 2 F; age 31+/-7 years) and 35 age-matched control subjects (15 M, 20 F; age 30+/-7 years) were scanned. The 5-HT(2A)R BP was determined for each voxel using the pseudoequilibrium ratio method on PET data obtained between 65 and 90 min after [18F]setoperone bolus injection. The resulting parametric 5-HT(2A)R BP images were spatially normalized using a ligand specific template. Analyses of covariance were done using SPM99 with age as covariate. In tests for the effect of schizophrenia and for partial correlations between 5-HT(2A)R BP and the five factors, corrected P values <0.05 at cluster or voxel level were considered significant. No significant differences were detected between patients and control subjects, and no significant correlations were observed between 5-HT(2A)R BP and any of the five factors. Thus, in agreement with the previous ROI studies, voxel-by-voxel analysis confirmed the lack of substantial 5-HT(2A)R BP differences between schizophrenic patients and control subjects.

Adult↗