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A M Downs

Publications and source records attributed to A M Downs.

At least 37 records · Page 2Linked to original sources
PubMed1999

Colophony allergy: a review.

Colophony is a complex mixture of over 100 compounds derived from pine trees. It has countless applications at home and at work and exposure to colophony and modified-colophony is universal. It is the oxidation products of unmodified and modified colophony and some of the new resin acids synthesized during modification that are the principle allergens in colophony. The neutral fraction may account for a small % of positive reactions. When screening for allergy using unmodified gum rosin, allergy to modified rosin will not be revealed. When patients react to both materials, it is probably due to unmodified colophony present in both, rather than a cross-reaction. Relevant positive reactions may be missed if only colophony 20% pet is relied upon as the screening material.

Allergens↗
PubMed1998

Heterosexual transmission of human immunodeficiency virus: variability of infectivity throughout the course of infection. European Study Group on Heterosexual Transmission of HIV.

Although individuals infected with human immunodeficiency virus (HIV) seem to be more infectious in the late stages of HIV infection and possibly also during the seroconversion period, most estimates of per-sexual-contact infectivity have been obtained without allowing for variability over the course of infection. In this analysis, a probabilistic model was fitted to data from a European study carried out between 1987 and 1992 that involved 499 (359 males and 140 females) HIV-infected subjects (index cases) and their regular heterosexual partners. The model used allowed infectivity (the per-sexual-contact HIV transmission probability, mu) to vary through three stages: the first 3 months following infection, the subsequent asymptomatic period, and the advanced stage (HIV-related clinical symptoms or a CD4-positive T lymphocyte count less than 200/mm3). Male-to-female infectivity through penile-anal sex was found to be higher in both the early and advanced stages of infection (mu=0.183) than in the longer intermediate period (mu=0.014) (p < 0.03). Failure to demonstrate significant differences between stages for other types of contact (male-to-female penile-vaginal contacts: mu=0.0007; female-to-male transmission: mu=0.0005) may reflect insufficient power rather than a true lack of variability. Indeed, the results for penile-anal sex suggest that persons who are in the process of seroconverting may be much more infectious than asymptomatic infected persons, whatever the type of contact. Prevention education should stress the risk of HIV transmission from subjects who may be unaware of their infection.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Time trends in HIV infection among pregnant women in Europe.

OBJECTIVE: To estimate time trends in HIV prevalence among pregnant women delivering livebirths in 14 European countries using a uniform methodology. METHODS: A form of back-projection was used to estimate HIV prevalence among pregnant women based on reported cases of AIDS due to perinatally acquired HIV infection. The method used estimates the rate of progression to AIDS in children with HIV, and the rate of transmission of HIV from mother to child, derived from published studies. RESULTS: The prevalence of HIV among pregnant women delivering livebirths was estimated to be highest in Spain (2.61 per 1000 livebirths in 1992-1993), relatively high (> or = 0.3 per 1000 livebirths) throughout the period 1984-1993 in France, Italy and Switzerland, and low (< 0.2 per 1000 livebirths) in Germany, The Netherlands and Scandinavia. There were large and statistically significant increasing trends in the estimated HIV prevalence among pregnant women in Portugal (an estimated 77% increase per 2-year period), Spain (40% increase) and the United Kingdom (77% increase; all P < 0.001). Statistically significant increasing trends of a smaller magnitude were estimated for France (24% increase) and Italy (23% increase; both P < 0.001). CONCLUSIONS: Sharp increases in HIV prevalence among pregnant women were estimated for several European countries, whereas in other countries no trends in the estimated prevalence were detected.

Adolescent↗
PubMed1998

Asymptotic fractals in the context of grey-scale images.

The estimation of the fractal dimension in the case of concave log-log Richardson-Mandelbrot plots can be obtained by using asymptotic fractal equations. We demonstrate here, under asymptotic fractal conditions, that additional derivations making use of the Minkowski dilation in grey-scales lead to two asymptotes, one having a slope of 1 and the other a slope of DT-D + 1 (where DT is the topological dimension and D the fractal dimension). The resulting equation offers important advantages. It allows: (i) evaluation of scaling properties of a grey-scale image; (ii) estimation of D without any iteration and (iii) generation of texture and heterogeneity models. We concentrate here on the first two possibilities. Images from cultured cells in studies of cytoskeleton intermediate filaments and kinetic deformability of endothelial cells were used as examples.

Endothelium, Vascular↗
PubMed1998

Nipple trauma.

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Humans↗