Incidence and Characteristics of Total Stroke in the United States

Background and Purpose  

Stroke, increasingly referred to as a "brain attack", is one of the leading causes of death and the leading cause of adult disability in the United States. It has recently been estimated that there were three quarters of a million strokes in the United States in 1995. The aim of this study was to replicate the 1995 estimate and examine if there was an increase from 1995 to 1996 by using a large administrative claims database representative of all 1996 US inpatient discharges.     

The adaptive evolution of plasticity: phytochrome-mediated shade avoidance responses

Many plants display a characteristic suite of developmental"shade avoidance" responses, such as stem elongation and acceleratedreproduction, to the low ratio of red to far-red wavelengths(R:FR) reflected or transmitted from green vegetation. ThisR:FR cue of crowding and vegetation shade is perceived by thephytochrome family of photoreceptors. Phytochrome-mediated responsesprovide an ideal system for investigating the adaptive evolutionof phenotypic plasticity in natural environments. The molecularand developmental mechanisms underlying shade avoidance responsesare well studied, and testable ecological hypotheses exist fortheir adaptive significance. Experimental manipulation of phenotypesdemonstrates that shade avoidance responses may be adaptive,resulting in phenotypes with high relative fitness in the environmentsthat induce those phenotypes. The adaptive value of shade avoidancedepends upon the competitive environment, resource availability,and the reliability of the R:FR cue for predicting the selectiveenvironment experienced by an induced phenotype. Comparativestudies and a reciprocal transplant experiment with Impatienscapensis provide evidence of adaptive divergence in shade avoidanceresponses between woodland and clearing habitats, which mayresult from population differences in the frequency of selectionon shade avoidance traits, as well as differences in the reliabilityof the R:FR cue. Recent rapid progress in elucidating phytochromesignaling pathways in the genetic model Arabidopsis thalianaand other species now provides the opportunity for studyinghow selection on shade avoidance traits in natural environmentsacts upon the molecular mechanisms underlying natural phenotypicvariation.     

Evaluating whether velar lobe size indicates food limitation among larvae of the marine gastropod Crepidula fornicata

Disproportionately large feeding structures have been used to infer food limitation in some marine invertebrate larvae, but few studies have investigated whether other factors alter larval morphology in similar ways. In this study, larvae of Crepidula fornicata were reared either at five different food concentrations of Isochrysis galbana (clone T-ISO) at a single temperature (22 degrees C) (Experiments I and II); or on three different phytoplankton species (Isochrysis galbana, Dunaliella tertiolecta, and Pavlova lutheri) at both high and low concentrations at a single temperature (22 degrees C) (Experiment III); or at high and low concentrations of Isochrysis galbana at four different temperatures between 16 and 25 degrees C (Experiment IV). Shell lengths and velar lobe dimensions were determined for individual larvae at intervals to monitor relative rates of velar and shell growth. In addition (Experiment V), fast growing and slow growing larvae in Experiment I were examined separately to determine whether velar lobes developed at similar rates (relative to shell growth) for fast and slow growing larvae within individual cultures. In general, velar lobes grew significantly larger, relative to shell length, when larvae were reared at low food concentrations (P<0.0001); for larvae of similar shell length, the velar lobes of those fed 1x10(4) cells ml(-1) were on average 17.7% larger than those of larvae fed 18x10(4) cells ml(-1) of T-ISO. In contrast, larvae fed different phytoplankton species at equivalently high food concentrations did not differ in relative velum size (P=0.2666), even though shell growth rates differed significantly for larvae raised on the different diets, indicating substantial variation in food quality. We also found that relative rates of velum and shell growth differed among fast and slow growing individuals within treatments. Temperature had no significant effect on relative rates of velar and shell growth within the 16-25 degrees C range tested (P=0.121), but may have altered the relationship between food concentration and relative velar growth. These results indicate that dramatically reduced food concentration induces disproportionate growth in the velar lobes of C. fornicata, but that interpretation of data from field-collected individuals of this species will be made difficult by the potentially confounding effects of temperature, food quality, and differences in individual growth potential. Assessments of food limitation using morphological measurements for field-collected larvae will need to be supplemented with other indicators before convincing conclusions about the extent of food limitation in C. fornicata can be drawn.     

Mutagenicity of the mycotoxin diacetoxyscirpenol on somatic and germ cells of mice

Genotoxicity of diacetoxyscirpenol (DAS) was studied on laboratory mice after intraperitoneal injection with single and repeated doses. DAS was administrated at three different dose levels (0.5, 0.75, and 1.0 mg/kg body weight). The study was conducted on both somatic and germ cells additional to the sperm morphology analysis. DAS treatment resulted in a significant reduction (P<0.01) in mitotic activity at all levels of doses tested, confirming that DAS is a potent protein and DNA synthesis inhibitor. At somatic cells (bone marrow) both structural and numerical chromosome abnormalities were observed. Single dose treatment showed significant abnormalities only with high dose treatment. In contrast, at repeated dose similar abnormalities were also observed with some significance but no systematic relation between the administrated dose and abnormalities ratio could be settled. In germ cells (testicles), structural and numerical abnormalities were also observed. In general, the frequencies of scored abnormalities at germ cells were lower than that the somatic cells. Sperm count test revealed a decrease in the number of released sperm after toxin treatment. Abnormalities of sperm shape (head and tail) were observed, confirming the positive correlation between cytogenetic damage and sperm abnormality. The results also proved that DAS is a very toxic mycotoxin, in addition to inducing chromosomal abnormalities, it causes a severe inhibition of DNA synthesis which subsequently affects the cell cycle and cell division. A good system for good harvesting practice and good food technology can lower the risk for the consumers.     

Gendered perceptions on infant feeding in Eastern Uganda: continued need for exclusive breastfeeding support

Background

In resource-poor settings, HIV positive mothers are recommended to choose between 'Exclusive breastfeeding' (EBF) or 'Exclusive replacement feeding' (ERF). Acceptability, Feasibility, Affordability, Sustainability and Safety (AFASS) has been the World Health Organization (WHO)'s a priori criteria for ERF the last ten years. 'AFASS' has become a mere acronym among many workers in the field of prevention of mother-to-child transmission of HIV, PMTCT. Thereby, non-breastfeeding has been suggested irrespective of social norms. EBF for the first half of infancy is associated with huge health benefits for children in areas where infant mortality is high. But, even if EBF has been recommended for a decade, few mothers are practicing it. We set out to understand fathers' and mothers' infant feeding perceptions and the degree to which EBF and ERF were 'AFASS.'

Methods

Eight focus groups with 81 informants provided information for inductive content analysis. Four groups were held by men among men and four groups by women among women in Mbale District, Eastern Uganda.

Results

Two study questions emerged: How are the different feeding options understood and accepted? And, what are men's and women's responsibilities related to infant feeding? A mother's commitment to breastfeed and the husband's commitment to provide for the family came out strongly. Not breastfeeding a newborn was seen as dangerous and as unacceptable, except in cases of maternal illness. Men argued that not breastfeeding could entail sanctions by kin or in court. But, in general, both men and women regarded EBF as 'not enough' or even 'harmful.' Among men, not giving supplements to breast milk was associated with poverty and men's failure as providers. Women emphasised lack of time, exhaustion, poverty and hunger as factors for limited breast milk production. Although women had attended antenatal teaching they expressed a need to know more. Most men felt left out from health education.

Conclusion

Breastfeeding was the expected way to feed the baby, but even with existing knowledge among mothers, EBF was generally perceived as impossible. ERF was overall negatively sanctioned. Greater culture-sensitivity in programs promoting safer infant feeding in general and in HIV-contexts in particular is urgently needed, and male involvement is imperative.

Trial Registration

The study was part of formative studies for the ongoing study PROMISE EBF registered at http://clinicaltrials.gov (NCT00397150).     

Seasonal variation in life history traits in two Drosophila species

Seasonal environmental heterogeneity is cyclic, persistent and geographically widespread. In species that reproduce multiple times annually, environmental changes across seasonal time may create different selection regimes that may shape the population ecology and life history adaptation in these species. Here, we investigate how two closely related species of Drosophila in a temperate orchard respond to environmental changes across seasonal time. Natural populations of Drosophila melanogaster and Drosophila simulans were sampled at four timepoints from June through November to assess seasonal change in fundamental aspects of population dynamics as well as life history traits. D. melanogaster exhibit pronounced change across seasonal time: early in the season, the population is inferred to be uniformly young and potentially represents the early generation following overwintering survivorship. D. melanogaster isofemale lines derived from the early population and reared in a common garden are characterized by high tolerance to a variety of stressors as well as a fast rate of development in the laboratory environment that declines across seasonal time. In contrast, wild D. simulans populations were inferred to be consistently heterogeneous in age distribution across seasonal collections; only starvation tolerance changed predictably over seasonal time in a parallel manner as in D. melanogaster. These results suggest fundamental differences in population and evolutionary dynamics between these two taxa associated with seasonal heterogeneity in environmental parameters and associated selection pressures.