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Lifetime Number (lifetime + number)
Selected AbstractsPrevalence and risk factors of human papillomavirus infection by penile site in uncircumcised Kenyan menINTERNATIONAL JOURNAL OF CANCER, Issue 2 2010Jennifer S. Smith Abstract Human papillomavirus (HPV) prevalence was estimated from 2,705 sexually active, uncircumcised, human immunodeficiency virus seronegative men aged 17,28 years in Kisumu, Kenya. HPV prevalence was 51.1% (95% confidence interval: 49.2,53.0%) in penile cells from the glans/coronal sulcus and/or shaft. HPV prevalence varied by anatomical site, with 46.5% positivity in the glans/coronal sulcus compared with 19.1% in the shaft (p < 0.0001). High-risk HPV was detected in 31.2% of glans and 12.3% of shaft samples (p < 0.0001). HPV16 was the most common type and 29.2% of men were infected with more than one HPV type. Risk factors for HPV infection included presence of C. trachomatis, N. gonorrhea, self-reported sexually transmitted infections, and less frequent bathing. Lifetime number of sexual partners and herpes simplex virus type-2 seropositivity were also marginally associated with HPV infection. [source] Prevalence and risk factors associated with antiretroviral resistance in HIV-1-infected childrenJOURNAL OF MEDICAL VIROLOGY, Issue 9 2007Constance Delaugerre Abstract In the USA and West Europe, nearly 80% of HIV-1-infected adults, experiencing virologic failure, harbored virus strain resistant to at least one antiretroviral drug. Limited data are available on antiretroviral drug resistance in pediatric HIV infection. The aims of this study were to analyze prevalence of HIV-1 drug resistance and to identify risk factors associated with resistance in this population. Prevalence of genotypic resistance was estimated retrospectively in treated children who experienced virologic failure (with HIV-1-RNA,>,500 copies/ml) followed in Necker hospital between 2001 and 2003. Among 119 children with resistance testing, prevalence of resistance to any drug was 82.4%. Resistance ranged from 76.5% to nucleoside reverse transcriptase inhibitor (NRTI), to 48.7% to non-nucleoside reverse transcriptase inhibitor (NNRTI) and 42.9% to protease inhibitor (PI). Resistance to at least one drug of two classes and three classes (triple resistance) was 31.9 and 26.9%, respectively. Resistance was not associated with geographic origin, HIV-1 subtype, and CDC status. In multivariate analysis, resistance to any drug remained associated independently with current low viral load and high lifetime number of past PI. Triple resistance was independently associated with the high lifetime number of past PI and with gender, particularly among children aged 11 years old or more with a prevalence seven times higher in boys than in girls. In conclusion, antiretroviral resistance is common among treated HIV-1-infected children and prevalence was similar with those observed in adult population in the same year period. However, adolescent boys seem to be at greater risk. J. Med. Virol. 79:1261,1269, 2007. © Wiley-Liss, Inc. [source] Stage, age and individual stochasticity in demographyOIKOS, Issue 12 2009Hal Caswell Demography is the study of the population consequences of the fates of individuals. Individuals are differentiated on the basis of age or, in general, life cycle stages. The movement of an individual through its life cycle is a random process, and although the eventual destination (death) is certain, the pathways taken to that destination are stochastic and will differ even between identical individuals; this is individual stochasticity. A stage-classified demographic model contains implicit age-specific information, which can be analyzed using Markov chain methods. The living stages in the life cycles are transient states in an absorbing Markov chain; death is an absorbing state. This paper presents Markov chain methods for computing the mean and variance of the lifetime number of visits to any transient state, the mean and variance of longevity, the net reproductive rate R0, and the cohort generation time. It presents the matrix calculus methods needed to calculate the sensitivity and elasticity of all these indices to any life history parameters. These sensitivities have many uses, including calculation of selection gradients. It is shown that the use of R0 as a measure of fitness or an invasion exponent gives erroneous results except when R0=,=1. The Markov chain approach is then generalized to variable environments (deterministic environmental sequences, periodic environments, iid random environments, Markovian environments). Variable environments are analyzed using the vec-permutation method to create a model that classifies individuals jointly by the stage and environmental condition. Throughout, examples are presented using the North Atlantic right whale (Eubaleana glacialis) and an endangered prairie plant (Lomatium bradshawii) in a stochastic fire environment. [source] Social facilitation affects longevity and lifetime reproductive success in a self-fertilizing land snailOIKOS, Issue 3 2000Bruno Baur Factors that reduce the reproductive output of self-fertilizing hermaphrodites are receiving increasing attention. The combined effects of reduced fecundity of selfing parents and inbreeding depression of the progeny have been referred to as self-fertilization depression. In isolated freshwater snails the reproductive output of selfing individuals also decreases due to the lack of social facilitation (absence of a conspecific). We examined the effect of social facilitation on lifetime reproductive success (number of young produced and longevity) over two generations in the simultaneously hermaphroditic land snail Balea perversa. In a parallel study we showed that B. perversa kept singly and in pairs reproduced exclusively by self-fertilization. In the parent generation, snails kept singly produced less offspring than snails kept in pairs. The difference in lifetime number of young was mainly due to differences in adult life span. Snails of the two groups did not differ in reproductive rate (number of young produced per 100 d of reproductive life) and hatchling size. In the offspring generation, snails kept singly did not differ from individuals kept in pairs in the lifetime number of young and hatchling survival. As in the parent generation, snails kept singly reproduced during a shorter period than snails kept in pairs. However, the shorter reproductive life span of snails kept singly was compensated for by a slightly (but not significantly) higher reproductive rate which resulted in a similar number of offspring produced for both groups. In both generations, snails of the two groups did not differ in size at first reproduction, adult growth rate and size at death. These findings suggest that social facilitation may affect longevity in selfing B. perversa. [source] Parent,Daughter Transmission of the Androgen Receptor Gene as an Explanation of the Effect of Father Absence on Age of MenarcheCHILD DEVELOPMENT, Issue 4 2002David E. Comings Based on an evolutionary theory of socialization, Belsky and colleagues proposed that girls exposed to a stressful environment, especially when due to father absence in the first 7 years of life, showed an early onset of puberty, precocious sexuality, and unstable relationships as adults. The authors of this article examined an alternative explanation that a variant X,linked androgen receptor (AR) gene, predisposing the father to behaviors that include family abandonment, may be passed to their daughters causing early puberty, precocious sexuality, and behavior problems. The results of a study of 121 White males and 164 White females showed a significant association of the short alleles of the GGC repeat polymorphism of the AR gene with a range of measures of aggression and impulsivity, increased number of sexual partners, sexual compulsivity, and lifetime number of sex partners in males; and paternal divorce, father absence, and early age of menarche in females. These findings support a genetic explanation of the Belsky psychosocial evolutionary hypothesis regarding the association of fathers' absence and parental stress with early age of onset of menarche and early sexual activity in their daughters. A genetic explanation of the father absence effect is proposed in which fathers carrying the AR alleles are more likely to abandon a marriage (father absence) and pass those alleles to their daughters in whom they produce an earlier age of menarche and behavioral problems. [source] | ||||||||||