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Biomedical subjects

W Stevens

Publications and source records attributed to W Stevens.

At least 19 recordsLinked to original sources
PubMed2006

Malaria prevention in The Gambia: patterns of expenditure and determinants of demand at the household level.

OBJECTIVE: To provide a better understanding of (1) the amounts households in The Gambia spend on a wide variety of malaria prevention measures, (2) how expenditure fluctuates throughout the year and (3) the main determinants of expenditure. METHODS: A random sample of 1700 households from the Farafenni region were interviewed about their expenditure on malaria prevention over the past 2 weeks. Interviews were staggered over 12 months. Expenditure was measured for bed nets, treating and repairing bed nets, aerosols, coils, indoor spraying, smoke and other prevention strategies such as drinking herbs and cleaning the outside environment. Results Expenditure on bed nets, including treatment and repair, constituted only 10% of total expenditure on malaria prevention. Every fortnight, households spent an average of 8.40 Dalasis (D) on coils, 4.20 D on indoor sprays, 3.09 D on smoke and 3.06 D on aerosols, together making up 81% of total fortnightly expenditure. Of the 442 households that did not own a bed net, 68% said it was because they could not afford one. Every 2 months, the same households spent an average of US 5 dollars, the equivalent to the cost of an insecticide treated bed net, on other forms of prevention. Total expenditure was 42% higher during the wet season than for the rest of the year. For every month of the year, coils were the dominant form of prevention expenditure. Wealth, age, occupation of household head, location of residence and month of the year were significant determinants of prevention expenditure. CONCLUSIONS: Households in The Gambia spend considerable amounts on a range of malaria prevention products and activities throughout the year. Bed nets represent a relatively small proportion of this expenditure even though they are perceived to be the most efficient and effective method of malaria control. A more concerted effort is needed to develop appropriate targeting strategies to encourage bed net use especially for children <5 years of age. Equal emphasis should be given to addressing barriers to purchasing nets such as their relative high upfront cost.

Adult↗
PubMed2006

HIV/AIDS prevalence testing--merits, methodology and outcomes of a survey conducted at a large mining organisation in South Africa.

OBJECTIVES: To determine the HIV prevalence rate at Anglo Platinum, a large, multinational organisation operating in South Africa (Gauteng, Limpopo and North-West), and to assess the merits, methodology and outcomes of the survey. METHODS: A sample of 11,339 individuals, representing 18.4% of the organisation's employees, were tested for HIV. HIV prevalence was determined using the Wellcozyme HIV 1+2 GACELISA test (oral fluid assay), and variables such as age, site, grade and gender were analysed. RESULTS: The overall prevalence rate was 24.6% (95% confidence interval (CI): 20.4-28.8), translating into approximately 15,167 HIV-infected individuals. Interestingly, there was considerable variation in prevalence between sites within the same geographical regions, highlighting the limitations of using data obtained from antenatal HIV surveillance surveys. As an example, the prevalence at sites in Limpopo province ranged from 9.8% to 19%, with the same basic demographic data in terms of race, age and gender. CONCLUSION: The survey data enabled the organisation to plan resource allocation appropriately for each business unit following their commitment to the treatment of infected employees with antiretroviral therapy. These baseline prevalence data also provide an opportunity for monitoring of proposed interventions using cross-sectional surveys at designated intervals in the future.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Chronic idiopathic thrombocytopenic purpura: present strategy, guidelines and new insights.

Idiopathic thrombocytopenic purpura (ITP) is an immune-mediated thrombocytopenia. The diagnosis is made after exclusion of other secondary causes of thrombocytopenic disorders. The primary treatment goal is to prevent severe bleeding rather than achieve normal platelet counts. In adults ITP usually has an insidious onset and chronic course. Although ITP is a relatively common haematological disorder, there are important unresolved issues in its management, especially for chronic refractory ITP patients. New therapeutic agents have changed strategies for ITP treatment. This article reviews the treatment indications and options of chronic ITP in adults in the literature and compares them with the treatment indications and treatment options used by the Dutch internist.

Adult↗
PubMed2005

Evaluation of two commercially available, inexpensive alternative assays used for assessing viral load in a cohort of human immunodeficiency virus type 1 subtype C-infected patients from South Africa.

Although human immunodeficiency virus type 1 (HIV-1) RNA is the acknowledged "gold standard" marker for monitoring disease activity in patients receiving highly active antiretroviral therapy (HAART), it remains unaffordable in resource-constrained settings. The present study investigated two commercially available kits for the detection of HIV-1 viral load markers as more affordable alternatives to HIV-1 RNA quantitation. The greatly improved heat-denatured, signal-boosted HiSens HIV-1 p24 Ag Ultra kit (Perkin-Elmer) and the ExaVir Load Quantitative HIV-RT kit (Cavidi Tech AB) were compared with the Amplicor HIV-1 Monitor (version 1.5) assay (Roche Molecular Systems Inc.). A total of 117 samples containing HIV-1 subtype C were analyzed by all three methodologies. Eighty-nine of these samples represented serial measurements from 20 patients receiving HAART. The remaining samples analyzed were from a group of treatment-naive patients. The association between the p24 antigen assay and the RNA assay was fairly strong (R(2) = 0.686). The association between the reverse transcriptase (RT) quantitation assay and the RNA assay was strong (R(2) = 0.810). Both alternative assays seemed most useful for the serial monitoring of patients receiving HAART (n = 89 plasma samples from 20 patients), as all assays showed a statistically significant downward trend over time, with the trend being either linear or curvilinear. In addition, all three assays showed negative correlations with the CD4 count (CD4 count versus RNA load, r = -0.336 and P = 0.001; CD4 count versus p24 antigen level, r = -0.541 and P < 0.0001; CD4 count versus RT level, r = -0.358 and P = 0.0006). Still of major concern are both the lack of sensitivity and the wide degrees of variability of both assays. However, both assays provide a less expensive alternative to the Roche viral load assay and demonstrate the same trends during treatment.

Antiretroviral Therapy, Highly Active↗
PubMed2005

Risk factors for defaulting from tuberculosis treatment: a prospective cohort study of 301 cases in the Gambia.

SETTING: An urban tuberculosis (TB) clinic, The Gambia. OBJECTIVE: To identify patient characteristics associated with increased rates of defaulting from treatment, specifically knowledge and cost factors amenable to intervention. DESIGN: Prospective cohort study of TB cases at least 15 years of age commencing treatment, interviewed by semi-structured questionnaire and followed for attendance at thrice-weekly directly observed treatment (DOT). RESULTS: Of 301 patients, 76 (25.2%) defaulted from treatment and 25 did not return for treatment. The defaulting rate was higher among those who said they were uncertain that their treatment would work (HR 3.64; 95%CI 1.42-9.31, P = 0.007) and among those who incurred significant time or money costs travelling to receive treatment (HR 2.67; 95%CI 1.05-6.81; P = 0.04). These factors had differing effects with respect to time: uncertainty over treatment success was important in the first 90 days of treatment, while increased cost of travelling to the clinic was important after 90 days. CONCLUSION: In The Gambia, risk groups for defaulting can be recognised at the start of treatment and are at highest risk at different times. Home-based self-administration of medications after 3 months of DOT should be considered as confidence in treatment success rises, and the costs of travelling to receive treatment start to take their toll.

Adolescent↗
PubMed2004

Evaluation of the NucliSens EasyQ assay in HIV-1-infected individuals in South Africa.

We compared the performance of the NucliSens EasyQ assay (bioMerieux) combined with the manual NucliSens miniMag extraction methodology to the Roche Cobas Ampliprep/Standard Amplicor Monitor methodology (Roche Diagnostics) for HIV-1 RNA quantitation in HIV-1-infected individuals in South Africa. Plasma samples (284) from HIV sero-positive patients at different stages of infection were analyzed. The distribution of results was typical of the clinical samples received at the laboratory where 20% have viral load results <400 copies/ml (2.6 log) and 18% have viral load results >750000 copies/ml (5.8 log) using the Roche Amplicor Monitor standard assay. All statistical analyses were performed using log10-transformed values for all the variables in the analyses, i.e. log10EasyQIU/ml, and log10RNA (log10 copies/ml, Amplicor). Roche values were converted from RNA copies per ml to IU/ml by multiplying the Roche value by 0.51. HIV RNA levels quantitated by the NucliSens EasyQ assay correlated significantly with those of the Roche Cobas Amplicor Monitor assay (r=0.874, p<0.0001). Reproducibility of the NucliSens EasyQ assay in the log6IU range yielded CV variance of 1.3-2.84% for two well-trained technologists. In addition, a retrospective evaluation of the performance of the NucliSens EasyQ assay in 102 runs (2448) samples was conducted in the laboratory over a 4-month interval. Factors considered during this evaluation included time taken to perform the assay, volume requirements, number of required repeats, potential for contamination.

Acquired Immunodeficiency Syndrome↗
PubMed2004

IgE antibodies of fish allergic patients cross-react with frog parvalbumin.

BACKGROUND: The major allergens in fish are parvalbumins. Important immunoglobulin (Ig)E cross-recognition of parvalbumins from different fish species has been shown. Recently frog parvalbumin alpha has been found to be responsible for a case of IgE-mediated anaphylaxis triggered by the ingestion of frog meat. The aim of this study was to investigate whether IgE antibodies of fish allergic persons cross-react with frog parvalbumin and to appreciate its clinical relevance. METHODS: The sera of 15 fish allergic patients and one fish and frog allergic patient were tested by IgE-immunoblotting against frog muscle extract. Sera were tested against recombinant parvalbumin alpha and beta from Rana esculenta. Skin prick tests were performed in selected patients with recombinant frog parvalbumin. Ca(2+) depletion experiments and inhibition studies with purified cod and frog recombinant parvalbumin were done to characterize the cross-reactive pattern. RESULTS: Fourteen of the sera tested had IgE antibodies recognizing low molecular weight components in frog muscle extract. Calcium depletion experiments or inhibition of patient sera with purified cod parvalbumin led to a significant or complete decrease in IgE binding. When tested against recombinant parvalbumins, three of 13 sera reacted with alpha parvalbumin and 11 of 12 reacted with beta parvalbumin from R. esculenta. Skin prick tests performed with recombinant frog parvalbumin were positive in fish allergic patients. Inhibition studies showed that a fish and frog allergic patient was primarily sensitized to fish parvalbumin. CONCLUSION: Cod parvalbumin, a major cross-reactive allergen among different fish species, shares IgE binding epitopes with frog parvalbumin. This in vitro cross-reactivity seems to be also clinically relevant. Parvalbumins probably represent a new family of cross-reactive allergens.

Animals↗
PubMed2002

Tuberculosis in children dying with HIV-related lung disease: clinical-pathological correlations.

SETTING: Chris Hani Baragwanath Hospital, Soweto, South Africa. OBJECTIVES: To compare post mortem histological, microbiological and biochemical findings with clinical and radiological data generated ante mortem in children infected with HIV dying from clinical lung disease. METHODS: Post mortem lung and liver biopsies were undertaken on 93 consecutive deaths in children with HIV. Specimens were processed for culture, histology and staining for M. tuberculosis, Pneumocystis carinii pneumonia (PCP) and cytomegalovirus (CMV). Post mortem diagnoses were compared with clinical and radiological data generated during the final hospitalisation. RESULTS: Tuberculosis (TB) was diagnosed post mortem in four (4.3%) cases; a further 17 (18.2%) patients had been treated empirically for TB before death, and the remaining 72 (77.5%) patients had not been treated for TB. TB was more prevalent in children aged 1 year or older (13.4%) than in younger patients (1.4%) (P < 0.025). Patients with PCP, CMV pneumonitis or lymphocytic interstitial pneumonitis (LIP) had the same clinical presentation or radiographic appearances as patients with TB. The only features distinguishing patients with TB were older age and ante mortem gastric aspirate cultures positive for M. tuberculosis. CONCLUSION: The diagnosis of TB in children infected with HIV remains difficult. Clinical and radiographic features are shared with other opportunistic diseases. Case identification strategies relying on clinical and radiographic findings lead to overtreatment, particularly in children younger than 1 year of age. Gastric aspirate cultures remain a reliable tool for the identification of infected patients.

Age Factors↗
PubMed2001

'More than just money' -- widening the understanding of the costs involved in cancer care.

AIM: This paper examines the literature relating to the wider concept of cost in cancer care and the implications this has for the development of services particularly within the changing context of cancer care. BACKGROUND: Cancer remains a major cause of morbidity and mortality in the United Kingdom (UK), treatment is often complex and expensive; both in financial and human terms. Service patterns for cancer care are shifting away from traditional inpatient, hospital settings towards short stay/day-care and home care models. This is in response to developments in health care policy, but it is also because of the availability of better tolerated treatments and demand for more patient-focused health care. REVIEW OF THE LITERATURE: The databases of Cinhahl and Medline were accessed using the keywords of costs, treatment, outpatients, home care and cancer. Additional sources of literature were also accessed through hand searching key journals. The paper explores the literature in three themes. First, the cost-effectiveness of cancer treatment; second, the often invisible indirect or 'out of pocket' costs incurred by patients and their families during cancer treatment and finally, the 'human costs' of a cancer diagnosis and cancer therapy. CONCLUSIONS: In view of recent calls to improve the effectiveness of cancer care in the UK, we suggest that research is needed to address all the dimensions of cost. It is only by exploring total costs from this broad perspective that appropriate, effective and holistic services can be planned for the future.

Ambulatory Care↗
PubMed2001

Curative resection for rectal carcinoma: definition influences outcome in terms of local recurrence.

OBJECTIVE: There are wide variations in local recurrence rate following curative surgery for rectal cancer and there are substantial inconsistencies among surgeons regarding the method of defining curative resection. This paper seeks to explore whether defining criteria is one of the important factors driving the variations in outcome. METHOD: A literature review was undertaken to find all UK-based studies that had data on curative resection and local recurrence rates. The studies were divided into groups with distinct definitions of curative resection for rectal cancer. Meta-analyses were performed to pool the risks of local recurrence by group definition. Statistical tests were used to explore the variation in local recurrence by group. Confounding relationships of age, sex, Dukes stage, length of follow-up and year of study were explored as far as possible given the limitations of the available data. RESULTS: For rectal cancers significant differences were found between the pooled local recurrence risks by group definition (P < 0.01). Meta-regression tests including all the studies indicate that the definition of curative resection is an important predictor of local recurrence. CONCLUSION: It is suggested that a standardized approach towards defining curative resection and local recurrence may have a significant effect on outcomes in colorectal cancer surgery and would enable comparisons to be made between different series.

Journal Article↗
PubMed2001

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 and multiple myeloma in South Africa.

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) has been implicated in the etiopathogenesis of multiple myeloma. Although the association is biologically plausible and attractive, conflicting data have been reported, including evidence against the involvement of KSHV in the pathogenesis of the disease. The purpose of this study was to determine the relationship between KSHV and myeloma in blacks in South Africa, in whom the disease is not uncommon and the seroprevalence of KSHV is higher than in the areas in which this association has been documented. Using a nested polymerase chain reaction (PCR) assay, the authors initially tested for the presence of KSHV DNA sequences (KS330(233)) in bone marrow aspirates, bone marrow biopsy material, and cultured bone marrow adherent cell samples of patients with myeloma. KSHV DNA sequences were detected in 4 of 10 (40%) of the adherent cell cultures and 1 of 20 (5%) of the bone marrow aspirate samples. None of the bone marrow biopsy samples (0/9) or control bone marrow aspirate samples (0/19) was positive. To confirm the positive results in the bone marrow cultures noted above and to exclude contamination, the procedure was repeated in a further 7 patients with myeloma and 11 controls with lymphoproliferative disorders using the same nested PCR assay. In addition, the authors used a different set of primers that recognize sequences internal to the 233-bp fragment to yield a final product of 186 bp. The authors were unable to detect any KSHV DNA sequences in the patients with myeloma (0/7) or the control patients with other lymphoproliferative disorders (0/11). Taken together, the finding of a positive result in 4 of 17 patients (23.5%), which is similar to the background seroprevalence rate, does not support a clear association between myeloma and KSHV in blacks in South Africa.

Adult↗
PubMed2001

The effects of insulin, glucose, and pyruvate on the kinetics of leptin secretion.

Leptin is a hormone that is secreted by fat cells and has roles in body weight regulation, glucose metabolism, reproduction, and other neuroendocrine functions. The purpose of this study was to determine whether the secretagogues, insulin, glucose, and pyruvate, enhance leptin secretion by increasing leptin synthesis, or whether these secretagogues stimulate the quantal release of a stored cytosolic pool of leptin. We found that in the absence of secretagogues, the rate of leptin secretion from isolated rat adipocytes approximately equals the rate of leptin synthesis. For 60 min after the addition of secretagogues, leptin synthesis rapidly increases, with little or no leptin secretion; leptin increases intracellularly by approximately 60% (P < 0.05). After 60 min, leptin is significantly released from cells. At 120 and 240 min, secretagogues enhance leptin secretion into the medium by 35% (P < 0.05) and 40% (P < 0.01), respectively. Cycloheximide prevents the synthesis and the secretagogue-mediated secretion of leptin. Monensin, an inhibitor of protein translocation, has no effect on leptin synthesis, but it blocks the secretagogue-mediated secretion of leptin. These findings suggest that secretagogues enhance leptin release by increasing leptin synthesis, rather than by enhancing the release of a preexisting cytosolic pool of leptin.

Adipocytes↗
PubMed2001

Health effects following chronic dosing with tungsten-iron and tungsten-polymer shot in adult game-farm mallards.

Permanent approval of shot composed of tungsten-iron and tungsten-polymer for waterfowl hunting by the U.S. Fish and Wildlife Service was pending the results of the present study that examined the health and reproductive effects of the two shot types on mallards (Anas platyrhynchos) over a 150-day period. We collected data pertaining to the effects of tungsten-iron and tungsten-polymer shot on mortality, body weight, organ weight, tissue pathology, and shot erosion. Thirty-two bird groups (sexes equal) of adult mallards were dosed orally with eight #4 steel shot (control), eight #4 tungsten-iron shot, or eight #4 tungsten-polymer shot on days 0, 30, 60, 90, and 120 of a 150-day trial (26 January 1998 to 25 June 1998). An additional 12 mallards (sexes equal) were dosed orally with eight #4 lead shot (positive control) on day 0 of the study. All lead-dosed ducks died by day 25, whereas no ducks died in the other treatment groups. Significant liver hemosiderosis was present in all control and tungsten-iron-dosed males, in five of eight control and three of eight tungsten-iron-dosed females, and in one tungsten-polymer-dosed male examined. The rate of shot erosion was highest for tungsten-polymer shot (99%), followed by tungsten-iron (72%), and steel (55%) shot. Tungsten-iron or tungsten-polymer shot repeatedly administered to adult mallards did not have deleterious health effects during the 150-day trial based on mortality, body weights, organ weights, and histology of the liver and kidneys.

Alloys↗