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Biomedical subjects

A Wilkins

Publications and source records attributed to A Wilkins.

At least 19 recordsLinked to original sources
PubMed1997

HIV type 2 pathogenicity is not related to subtype in rural Guinea Bissau.

Data from an MRC case-control study in rural Guinea Bissau suggest older HIV-2 carriers (aged 55 to 80 years) appear, over a period of 2 years, to have a mortality similar to that of uninfected controls, whereas in HIV-2 carriers under the age of 55 there is a significantly higher mortality, compared with uninfected controls. Genotyping of viruses from both groups revealed only subtype a to be circulating. Thus, although putative nonpathogenic HIV-2 subtypes have been described in patients from West Africa, these do not appear to be contributing significantly to the nonpathogenic clinical phenotype in this population.

Aged↗
PubMed1996

A community-based study of human immunodeficiency virus type 2 provirus load in rural village in West Africa.

A community-based study of provirus load in human immunodeficiency virus (HIV) type 2-infected subjects was done in a rural village in Guinea-Bissau. HIV-2 provirus load varied considerably, with a geometric mean of 124.3 (95% confidence interval, 86.0-179.6) copies/10(5) CD4 cells, which is a level similar to that found in HIV-1 infection. Neither malaria parasitemia, active syphilis, or human T cell leukemia virus coinfection significantly influenced provirus load, nor did age. Eleven of 104 HIV-2-infected subjects had died after 3 years of follow-up; 9 of those who died had a high provirus load of > or = 100 copies/10(5) CD4 cells and a relatively low CD4 cell percentage of < 29%.

Adult↗
PubMed1996

Age of wife as a major determinant of male-to-female transmission of HIV-2 infection: a community study from rural West Africa.

OBJECTIVE: To examine whether proviral load is important for transmission between spouses, since we have previously found that the proviral load of HIV-2 predicts the severity of infection. DESIGN: Proviral load was examined in 121 HIV-2-infected adults in a rural area of Guinea-Bissau. For the 68 subjects who had a spouse of known HIV status the risk of the spouse being infected was examined. METHODS: Statistical methods for dependent data were used, because several couples were polygamous. RESULTS: Twenty-seven HIV-2-infected men had 52 current wives of whom 17 (33%) were HIV-2-seropositive. Forty-one HIV-2-infected women had 36 current husbands of known HIV serostatus; nine (25%) were HIV-2-positive. In univariate analyses, concordance of female partners of HIV-2-infected men increased with a previous history of prostitution, age of wife, lack of age difference between the spouses, number of previous husbands, number of wives of the man, and the proviral load. The only significant predictor of concordance in multivariate analyses when wives with a history of prostitution were excluded was an age of 45 years or older [odds ratio (OR), 8.68; 95% confidence interval (CI), 2.34-32.22]. This tendency was not explained by the length of current marriage. Although husbands with a high proviral load were more likely to have concordant spouses than those with a low proviral load (< 20 copies/10(5) CD4 cells), this association was not statistically significant (OR, 2.59; 95% CI, 0.90-7.46). Among spouses of HIV-2-infected women, none of the examined factors, including previous prostitution or proviral load in the woman, predicted whether the husband was HIV-2-infected. CONCLUSIONS: Women appear to be more susceptible to HIV-2 infection after 40-45 years of age. The apparent change in susceptibility may be a major reason for the distinctive age pattern of HIV-2 infection observed in West Africa.

Adolescent↗
PubMed1994

HIV type 2 proviral load measured by quantitative polymerase chain reaction correlates with CD4+ lymphopenia in HIV type 2-infected individuals.

The efficiency of detection of 2 sets of primer pairs from putatively conserved regions of the human immunodeficiency virus type 2 (HIV-2) genome were assessed in 86 seropositive individuals from The Gambia by nested polymerase chain reaction (PCR). HIV-2 long terminal repeat (LTR) target sequences were detected in DNA extracted from peripheral blood mononuclear cells (PBMCs) in 84 of 86 (97%) individuals whereas HIV-2 integrase (pol) gene sequences were detected in 39 of 41 (95%) individuals. The use of LTR target sequences and recombinant Pfu DNA polymerase, rather than Taq polymerase, in a modified secondary amplification reaction mediated the incorporation of 35S-labeled nucleotides in a quantitative radiometric assay. This sensitive assay was used to quantify HIV-2 proviral DNA in clinical samples and compared well with estimations by limiting end-point dilution of target molecules. A linear response between counts and the number of copies amplified from serial dilutions of pROD10 plasmid DNA (3-2000 copies) yielded a standard curve to allow extrapolation to clinical data. Increased levels of HIV-2 proviral DNA, expressed as copies per 10(5) CD4-positive lymphocytes, were associated with declining CD4 count in 63 adult patients (Spearman rank correlation, r = -0.71, n = 63, p < 0.001) and with the occurrence of HIV-related clinical disease. Kruskall-Wallis analysis of variance analysis showed the mean proviral copy number (log10) to be significantly different between groups (p < 0.001) where CD4 counts were grouped as < 200/mm3 (3.4 +/- 1.05 copies), 200-500/mm3 (2.84 +/- 0.93 copies), and > 500/mm3 (1.88 +/- 0.43 copies).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effects of HIV-2 infection in a rural area of Guinea-Bissau.

OBJECTIVE: To investigate the clinical and immunologic effects, and pattern of mortality associated with HIV-2 infection. SETTING: A rural community in Guinea-Bissau. METHODS: Serologic screening of 2774 subjects aged > 14 years followed by studies of the prevalence of clinical and immunologic abnormalities among 133 subjects with HIV-2 infection and 160 seronegative controls, and surveillance of mortality among all subjects who were screened during a mean of 2 years of follow-up. RESULTS: Generalized lymphadenopathy was the only clinical abnormality significantly associated with HIV-2 infection. Infection was associated with lower CD4 counts and higher beta 2-microglobulin and neopterin levels. During follow-up, 5.5% of infected subjects died compared with 1.8% of the seronegatives (rate ratio adjusted for age and sex, 3.5; 95% confidence interval ((CI), 1.8-6.7). Proportional hazard regression analysis showed that the rate ratio varied with age (P = 0.003) and there was some evidence that the excess of mortality in infected subjects was, in absolute terms, least in the oldest subjects (trend test; P = 0.08). CONCLUSIONS: The findings support previous suggestions that HIV-2 is less pathogenic than HIV-1; the data also suggest that mortality associated with infection may be lower in older subjects.

Adolescent↗
PubMed1994

HIV-2-infected patients survive longer than HIV-1-infected patients.

OBJECTIVE: To compare survival of patients infected with HIV-1 and HIV-2. DESIGN: Longitudinal follow-up of 175 HIV-1- and 294 HIV-2-infected patients identified in, or referred to a hospital in The Gambia. METHODS: Survival analysis methods were used and the death rate ratios for HIV-2 relative to HIV-1 patients were estimated using proportional hazard regression models that allowed for age, sex and clinical or immunological features. RESULTS: The overall death rate ratio for HIV-2 relative to HIV-1 was 0.67 [95% confidence interval (CI), 0.49-0.91] when adjusted for age, sex and World Health Organization Bangui clinical classification. When allowing for age, sex and three strata of CD4+ count, the rate ratio was 0.64 (95% CI, 0.43-0.94), and for three strata of beta 2-microglobulin levels 0.60 (95% CI, 0.42-0.84). CONCLUSION: Mortality rate in HIV-2-infected patients is approximately two-thirds of that for HIV-1-infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Overlays for classroom and optometric use.

Perceptual distortion of printed text can sometimes be reduced by placing upon the page a sheet of coloured plastic (overlay). The colour that best reduces the distortion differs from one individual to another and may need to be selected with precision. A set of overlays has been developed that samples the CIE UCS diagram systematically. The overlays are robust and have a matte finish. They can be combined in an intuitive way to provide a wide range of chromaticities.

Audiovisual Aids↗
PubMed1993

Competitive EIA for anti-HIV-2 detection in The Gambia: use as a screening assay and to identify possible dual infections.

The performance of a competitive EIA for the detection of HIV-2-specific antibody utilising a viral lysate antigen was assessed over a 3 year period in The Gambia, West Africa, and compared with a commercially available assay, ELAVIA-2, using three panels of sera. An immunodominant region of the transmembrane glycoprotein of an HIV-2 isolate (ANT 53) was also cloned and expressed in E. coli as a beta-galactosidase fusion protein and the resulting recombinant protein substituted in place of the existing viral lysate antigen. Competitive EIAs were found to be both a specific and sensitive means of reliably determining the HIV-2 status of an individual with a high predictive value, particularly when a strategy of concordant positive results in the two EIAs was used. When either anti-HIV-2 competitive EIAs were used in conjunction with a competitive EIA for anti-HIV-1 detection it was possible in the vast majority of cases to identify the virus-type infecting an individual and speciate HIV-1 and HIV-2 infections. A few sera which showed similar regression profiles when diluted over a serial tenfold dilution steps were identified as possible dual infections.

Acquired Immunodeficiency Syndrome↗
PubMed1993

The effects of post-test counselling on condom use among prostitutes in The Gambia.

OBJECTIVES: To determine the effect of counselling on condom use by prostitutes. DESIGN: Cohort study. SETTING: Field-based study in The Gambia. PARTICIPANTS: Thirty-one (12 HIV-positive and 19 HIV-negative) prostitutes. INTERVENTIONS: Post-test HIV counselling. MAIN OUTCOME MEASURES: Levels of condom use. RESULTS: Overall, counselling had no effect on condom use. CONCLUSIONS: Scarce resources should be directed towards providing condoms in bars rather than counselling.

Cohort Studies↗
PubMed1993

Determinants of condom use in 24,000 prostitute/client contacts in The Gambia.

OBJECTIVE: To determine the factors that influence condom use among prostitutes and their clients in The Gambia. DESIGN: A cohort of 181 prostitutes working in seven bars and several rural markets in The Gambia were monitored daily for 14 months. A sample of 747 clients of these prostitutes was also questioned. MAIN OUTCOME MEASURE: Proportion of sexual contacts for which a condom was used. RESULTS: Data on 24,181 sexual contacts reported by the prostitutes indicated condom use varied according to type of partner (from 84% with clients to only 4% with regular partners). Condom use with clients varied according to location (from 91% in high-class bars to 59% in rural markets), decreased from 91% with the first client of the evening to 37% with the tenth client, and from 75% with clients paying higher charges (> D19) to 52% with those paying lower charges (< D20). Condom use was not related to the socio-demographic characteristics of the prostitutes. Clients reported lower condom use than prostitutes. Clients aged 20-24 years were least likely to use condoms, while white collar workers, traders, and those paying higher charges, were more likely to use condoms. CONCLUSIONS: The level of condom use in this cohort of prostitutes was high but not consistent. Condom use was determined more by the type of establishment and the characteristics of clients, than by any fixed tendency among the prostitutes. Thus, education campaigns should be directed as much to clients as to prostitutes. In The Gambia, 'lower-class' bars and those in rural areas where prostitutes work should be a priority target.

Adolescent↗
PubMed1993

The epidemiology of HIV infection in a rural area of Guinea-Bissau.

OBJECTIVES: To determine the prevalence of HIV infection and its relationship to age, sex and other factors. DESIGN AND SETTING: Cross-sectional survey of a rural community in Guinea-Bissau. METHODS: Questionnaire-administration and screening of sera from subjects aged > or = 15 years. RESULTS: Of the 2770 subjects tested, 220 (7.9%) were HIV-2-seropositive, four (0.1%) were HIV-1-seropositive and 10 (0.4%) were dually reactive. Overall prevalence of HIV-2 was 9.3% in women, peaking at 17.2% in the 35-44 age group, and 6.6% in men, peaking at 19.1% in the 45-54 age group. The mean age of the four subjects with HIV-1 infection was 24 years, which was significantly lower than those with HIV-2 infection. HIV-2 infection was more prevalent among women who were widowed or divorced, women whose husbands were living away from the study area, and women who had lived in the capital, Bissau. The majority of subjects with an infected spouse remained uninfected and none of the women aged < 25 years whose husbands were infected were seropositive. The prevalence varied significantly between settlements within the study area. CONCLUSIONS: The pattern of HIV-2 infection in this rural community has similarities to that found in urban Bissau, and prevalence in both areas peaks in older subjects than in HIV-1 foci. The findings support previous suggestions that HIV-2 is not a recent introduction to Guinea-Bissau, and that it is less pathogenic and less readily transmitted than HIV-1.

Adolescent↗
PubMed1993

Immunological responses of Gambians in relation to clinical stage of HIV-2 disease.

This study describes a broad spectrum of cellular and antibody-mediated immune responses found in 28 asymptomatic and 37 symptomatic Gambian patients with HIV-2 infection. It shows that these responses vary according to the stage of infection as described by three clinical staging systems. The first system was a local one based on the signs used for the WHO Bangui clinical definition of AIDS, the second, suggested by WHO, was based on a performance scale, and the third was that used by the Centre for Disease Control. Asymptomatic patients had significantly lower mean CD4 counts, lymphoproliferative and interferon-gamma (IFN-gamma) responses and lower IgG and IgM antibody responses to keyhole limpet haemocyanin (KLH) than controls. These measurements and the size of the skin test reaction to purified protein derivative (PPD) or Candida antigen declined significantly according to the stage of infection. Mean values of the serological markers beta 2-microglobulin and neopterin and antibody titres to Epstein-Barr virus capsid antigen (EBVCA) rose significantly according to severity of disease. The Gambian or WHO clinical staging systems, which are easy and cheap to apply, may serve as an alternative to sophisticated and expensive immunological measurements when trying to stage disease and predict prognosis.

Adult↗
PubMed1993

Open trial of subjective precision tinting: a follow-up of 55 patients.

We gave glasses, tinted using new techniques, to 55 patients with visual discomfort and a range of associated complaints. The techniques permitted the patients to adjust the colour and saturation of tint for maximum clarity and comfort when viewing text. Benefit was experienced by 45 patients (82%) who were still using them more than 10 months later. Of these, 40 presented with a perceptual distortion of text that the glasses alleviated; 86% reported migraine in the family. An independent series of 74 children with reading difficulty was examined using coloured plastic sheets placed upon a page of text. Of those reporting beneficial effects of colour, 60% had migraine in the family, as compared with 31% of those for whom colour was of no benefit.

Adolescent↗