Epidemiological and clinical aspects relating to the variability of rheumatoid arthritis

OBJECTIVE: To review epidemiological studies dealing with the temporal and geographic variability in the occurrence of rheumatoid arthritis (RA) and clinical studies that address the variability of severity and manifestations among populations. METHODS: An extensive search of the literature, including a Medline search, was completed. Studies addressing the origin, history, and trends in the occurrence of RA were reviewed first. Next, studies of the prevalence and incidence of RA in different populations were reviewed, and occurrence rates compared. Standardization was attempted by tabulating adult prevalence rates of studies using equivalent sets of criteria. Studies comparing RA patients from two populations were sought next. Finally, studies dealing with explanations of the presumed variability were reviewed. RESULTS: Temporal variability is indicated by paleopathological evidence that RA has existed in the New World since 4000 BC, whereas there is no evidence that it occurred in Europe before the 17th century, or in Africa before the 20th century. Epidemiological studies show a possible trend of decreasing incidence of RA in the United States and Western Europe, whereas reports from Africa note a rising incidence. In white populations of Europe and America, prevalence is approximately 1%, and incidence is 0.03%. Significantly higher rates are found in some North American Indians, and significantly lower rates in some Asian and African populations, even when the different population structures are taken into account. In the latter populations, different patterns of occurrence from those observed in whites emerge, such as greater female preponderance and a much younger peak age at onset. Direct standardized comparisons of two diverse populations of RA patients showed some differences in expression, severity, or manifestations of RA between populations. CONCLUSION: The occurrence and manifestations of RA are temporally and geographically variable.     

Online Communication and Adolescent Well-Being: Testing the Stimulation Versus the Displacement Hypothesis

The aim of this study was to contrast the validity of two opposing explanatory hypotheses about the effect of online communication on adolescents' well-being. The displacement hypothesis predicts that online communication reduces adolescents' well-being because it displaces time spent with existing friends, thereby reducing the quality of these friendships. In contrast, the stimulation hypothesis states that online communication stimulates well-being via its positive effect on time spent with existing friends and the quality of these friendships. We conducted an online survey among 1,210 Dutch teenagers between 10 and 17 years of age. Using mediation analyses, we found support for the stimulation hypothesis but not for the displacement hypothesis. We also found a moderating effect of type of online communication on adolescents' well-being: Instant messaging, which was mostly used to communicate with existing friends, positively predicted well-being via the mediating variables (a) time spent with existing friends and (b) the quality of these friendships. Chat in a public chatroom, which was relatively often used to talk with strangers, had no effect on adolescents' well-being via the mediating variables.     

Psychosocial causes and consequences of pathological gaming

Pathological use of computer and video games has been associated with indicators of psychosocial well-being, such as loneliness, low self-esteem, low social competence, and low life satisfaction. However, few studies have decisively demonstrated whether these indicators of psychosocial well-being are causes or consequences of pathological gaming. To address this gap in the literature, we conducted a two-wave panel study among 851 Dutch adolescents (543 gamers). Causal relations were analyzed using autoregressive structural equation models. These analyses indicated that social competence, self-esteem, and loneliness were significant predictors of pathological gaming six months later. Thus, lower psychosocial well-being can be considered an antecedent of pathological gaming among adolescent gamers. Our analyses further indicated that loneliness was also a consequence of pathological gaming. This suggests that displacement of real-world social interaction resulting from pathological use of video games may deteriorate existing relationships, which could explain the increase in adolescent gamers’ feelings of loneliness.     

Lower bounds for the divergence of orientational estimators

This paper is concerned with the properties of estimators in O(n,p),the n×p orthogonal matrices. It is shown that it is natural to introduce the notion of a parallel estimator where the expected value of the estimator must lie in normal space (orthogonal complement of tangent space) of O(n,p) at the true value. An appropriate measure of variance, referred to as divergence, is introduced for a parallel estimator and a Cramer-Rao (CR) type bound is then established for the divergence. The well-known Fisher-von Mises matrix distribution is often used to model random behavior on O(n,p) and depends on parameters Θ∈O(n,p) and H a p×p symmetric matrix. The bound for this distribution is calculated for the case n=p=3 and the divergence of the maximum-likelihood estimator (MLE) of Θ is estimated by simulation. The bound is shown to be tight over a wide range of H     

What do children value in entertainment programs? A cross-cultural investigation

We investigated which program characteristics in children's entertainment television programs children between 6 and 11 years of age value. We collected data by means of questionnaires among 100 Dutch and 100 U.S. first through fourth graders. The most important characteristics for both Dutch and U.S. children were comprehensibility and action, closely followed by humor, interestingness, innocuousness, realism, violence, and romance, respectively. Compared to Dutch children, U.S. children attached more value to realism, innocuousness, and interestingness. Boys in both samples attached more value to action and violence in a children's program, whereas girls in both samples attached more value to innocuousness and comprehensibility.     

Characteristics and determinants of sumatriptan-associated chest pain

Analysis of epitopes recognized by therapeutic monoclonal antibodies (mAb) is critical in clinical applications and in structure/function studies of target antigen. mAb MGr6 recognizes the extracellular domain of the p185HER2 oncoprotein and is a promising candidate for cancer immunodiagnosis and immunotherapy. Thus, epitope location and structure on p185HER2 need to be investigated. The use of MGr6-selected phage-displayed peptides for epitope analysis served to dissect the MGr6 epitope into at least two subregions, mimicked by CHSDC- and (L)P-(L)K(L) phage displayed peptides, respectively. Comparison of amino acid sequences of CHSDC peptides with the p185HER2 protein sequence and analysis of MGr6 reactivity with p185HER2 deletion mutants identified the linear subregion CCHEQCAAG of the MGr6 epitope, corresponding to amino acids 235-243 of the p185HER2 protein. This continuous subregion is part of a larger conformational epitope, and other amino acids, including a proline, a lysine and leucine residues contained in (L)P-(L)K(L) phage-displayed peptides appear to contribute to the formation of the MGr6 epitope surface.     

Influence of TV on daydreaming and creative imagination: A review of research.

The research literature is reviewed on the influence of TV on daydreaming and creative imagination. The hypotheses proposed to explain why TV might influence children's and adults' daydreaming and creative imagination positively (stimulation hypothesis) or negatively (reduction hypothesis) are discussed. The hypotheses that propose that existing daydreaming patterns result in changes in viewing behavior are also discussed. The weight of the available evidence favors the hypotheses that TV viewing stimulates daydreaming and reduces creative imagination, although decisive evidence of a causal relationship is lacking. The assumptions that underlie the hypotheses about TV's relationship to daydreaming and creative imagination are analyzed, and whether these assumptions have been supported by research is established. (PsycINFO Database Record (c) 2010 APA, all rights reserved)