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Biomedical subjects

A Wilkins

Publications and source records attributed to A Wilkins.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1993

Variations in three cardiovascular disease risk factors in Missouri, 1986-1992.

In 1991, cardiovascular disease claimed the lives of over 22,000 Missourians. Recent studies show that much of this mortality can be eliminated through risk factor reduction and early detection. This article examines the regional and demographic differences in three major cardiovascular disease risk factors and outlines some steps that physicians and other health care providers can take to reduce their prevalence.

Adult↗
PubMed1992

Prostitutes and their clients: a Gambian survey.

The social backgrounds and working behaviour of 248 prostitutes in urban and rural areas of The Gambia were investigated. Prostitutes were found to be highly mobile, moving frequently between a number of working locations in The Gambia and neighbouring Senegal, from which most of them originated. The educational level of prostitutes and the standard of living of their natal families were above average. Prostitutes worked on average four days a week and had between two and three clients a night. Condoms were used in up to 80% of contacts. 795 clients of prostitutes were interviewed and found to be on average of low educational and occupational status. Half were non-Gambian and most were currently travelling or living away from home.

Abortion, Therapeutic↗
PubMed1992

Clinical and laboratory predictors of survival in Gambian patients with symptomatic HIV-1 or HIV-2 infection.

OBJECTIVES: To determine which clinical and immunological features of patients with symptomatic HIV-1 and HIV-2 infection best predict survival in The Gambia. METHODS: All patients presenting to two hospitals in The Gambia between January 1987 and June 1990 with symptoms or signs suggesting chronic HIV infection were tested for HIV-1 and HIV-2 antibodies. Eighteen HIV-1 and 31 HIV-2-infected patients were recruited to the study, investigated intensively on admission and followed up until the end of 1990. Presenting clinical features, such as Karnofsky score, diagnosis of AIDS according to World Health Organization Bangui or Centers for Disease Control criteria and number of associated infections, together with five immunological measurements, as well as type of HIV infection, were related to length of survival using proportional hazard models fitted to Kaplan-Meier plots of survival times. RESULTS: Karnofsky score and diagnosis of AIDS were the best clinical predictors of survival. Type of HIV infection or number of associated infections did not predict outcome. The most powerful laboratory predictors were log(e) serum neopterin level, CD4 cell count and log(e) serum beta 2-microglobulin (beta 2M) level. The estimated median survival times (90% confidence interval) of the HIV-1 and HIV-2-infected were six (4-11) and 13 (9-20) months, respectively. These survival times do not differ significantly. CONCLUSIONS: The Karnofsky score and measurements of serum neopterin or beta 2M, which are easier and cheaper to perform than CD4 counts, may prove to be useful guides to prognosis for HIV infection in Africa.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Preliminary observations concerning treatment of visual discomfort and associated perceptual distortion.

A system for therapeutic precision tinting is described. Some individuals who are subject to perceptual distortion of text no longer perceive the distortion when the text has a particular colour. A simple colorimeter enables an observer to illuminate text with light of a particular chromaticity, varying first CIE 1976 hue angle (huv), then saturation (suv), and then luminance, to obtain a setting that maximizes visual comfort and reduces any perceptual distortion. The colorimeter setting is then matched by a combination of tinted trial lenses. The combination uses only two dyes at a time from a selection of seven, unless a dark lens is required, when a third neutral (grey) dye is added. The subject observes both text and a normal scene when wearing tinted trial lenses. A variety of trial lenses are compared including those that match the colorimeter setting and others with similar hue angle. Spectacle lenses are then tinted so as to have a spectral transmission identical to that of the chosen combination of trial lenses. Certain patients with reading disorders, eye-strain, headaches or photosensitivity epilepsy report benefit when wearing spectacles tinted according to the above techniques. The physiological basis for the therapeutic effects is uncertain, but may involve a selective impairment of luminance or colour-difference channels.

Adolescent↗
PubMed1991

Risk factors for HIV-2 infection in The Gambia.

A serosurvey was carried out to assess the prevalence of HIV infection in The Gambia and the importance of possible risk factors. The overall prevalence of HIV-2 infection among the 4228 adults studied was 1.7% while that of HIV-1 was 0.1%. The prevalence of HIV-2 was similar in both sexes but higher among those greater than 25 years of age and those who lived in two small towns along a main transport route. Among men, multivariate analysis showed prevalence of HIV-2 infection was significantly greater among those in the more affluent occupations, those without a secondary education and those with a history of urethral discharge. Among women, infection was more frequent in divorcees and widows and those who had been married several times. The prevalence was also higher in individuals born in Guinea-Bissau and in an ethnic group which originated there.

Adolescent↗
PubMed1991

Some visual, optometric and perceptual effects of coloured glasses.

We examined 20 individuals who had worn coloured glasses (Irlen filters) for a period of at least 3 months and who claimed to find them beneficial. Sixteen had a history of reading difficulties. The performance of a variety of visual tasks was compared: (1) using the coloured lenses; (2) using neutral density filters of similar photopic transmittance; and (3) using trial lenses to correct any residual refractive error. The coloured lenses appeared to reduce discomfort and susceptibility to anomalous perceptual effects upon viewing grating patterns. They also improved the speed of visual search by a small amount. The lenses had idiosyncratic effects on ocular muscle balance and acuity. They did not affect contrast sensitivity at a spatial frequency of 4 c/deg.

Adolescent↗
PubMed1986

Adult schistosome cDNA libraries as a source of antigens for the study of experimental and human schistosomiasis.

Protective immunity has been demonstrated in experimental schistosomiasis and is also believed to occur in man. It can be mediated by antibodies from infected animals or animals immunized with attenuated organisms. Recombinant Escherichia coli synthesizing antigenic polypeptides from the three principal species of schistosome that infect man, Schistosoma mansoni, S. japonicum and S. haematobium, have been constructed. Libraries of adult worm cDNA were prepared from each species in the expression vector lambda gt 11 and directly screened with antibodies from animals experimentally immunized with S. mansoni and S. japonicum and from humans infected with S. haematobium. The S. mansoni clones have been analysed in greatest detail. At least four different types of clones were identified. All the detected recombinant polypeptide antigens were recognised by antibodies from chronically infected mice and most were also recognised by antibodies from mice immunized with attenuated cercariae and anti-surface membrane antibodies. Clones synthesizing species-specific antigens for both S. mansoni and S. japonicum were identified by simultaneous screening of both libraries. At least three types of S. haematobium clones were identified by screening with human infection serum, most of which were species-specific. All the antigens were in the form of fusion peptides with E. coli beta-galactosidase and their expression was induced by isopropylthiogalactopyranoside. Since known protective monoclonal antibodies recognise highly glycosylated membrane proteins which cannot be identified in the form of nascent polypeptides, the direct identification of polypeptide antigens defined by their reactivity, as reported here, is an essential step in producing reagents by recombinant DNA technology, suitable for vaccination and diagnosis.

Animals↗