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Background: Sickness absence in Sweden is high, particularly in young women and the reasons are unclear. Many Swedish women combine parenthood and work and are facing demands that may contribute to impaired health and well-being. We compared mothers and women without children under different conditions, assuming increased sickness absence in mothers, due to time-based stress and psychological strain., Methods: All women born in 1960-79 (1.2 million) were followed from 1993 to 2003. Information on children in the home for each year was related to medically certified sickness absence with insurance benefits the year after. We used age and time-stratified proportional hazard regression models accounting for the individual's changes on study variables over time. Data were retrieved from national administrative registers., Results: Sickness absence was higher in mothers than in women without children, the relative risks decreased by age, with no effect after the age of 35 years. An effect appeared in lonely women irrespective of age, while in cohabiting women only for the ages 20-25 years. Mothers showed increased sickness absence in all subgroups of country of birth, education, income, sector of employment and place of residence. The relation between number of children and sickness absence was nonlinear, with the highest relative risks for mothers of one child. The upward trend of sickness absence at the end of 1990s was steeper for mothers compared to women without children., Conclusion: Despite the well-developed social security system and child care services in Sweden, parenthood predicts increased sickness absence, particularly in young and in lone women.

Several competing hypotheses have been put forward to explain why females of many species mate preferentially with males possessing the most conspicuous signals (e.g., ornaments, displays, or songs). We performed a laboratory experiment using two species of poison frogs, Dendrobates leucomelas and Epipedobates tricolor, to test the hypothesis that male calling performance is an honest indicator of parental quality. Our analyses are based on data from behavioral observations of mating activities of captive-reared individuals (and their offspring) that were housed in terraria for four consecutive breeding seasons. Male mating success increased with male calling rate and chirp duration in both species, suggesting that females preferred males with more elaborate calls. Because calling performance improved with age in D. leucomelas, female poison frogs that prefer males with more elaborate calls in the wild may end up mating with older males that have already proven their ability to survive. Females that mated with good callers obtained higher quality offspring. Eggs fertilized by males with high calling rates and long chirp durations had higher hatching success and produced tadpoles that were more likely to metamorphose into surviving frogs. As a consequence, females that mated with males with high calling performance obtained more surviving offspring per egg, compared to females that mated with poor callers. Collectively, our findings comply with the notion that female poison frogs prefer to mate with good callers because calling performance is a reliable predictor of offspring quality. The possible influence of maternal allocation and reasons for the strong effect size compared to previous studies are discussed.

Conspicuous coloration is often used in combination with chemical defenses to deter predators from attacking. Experimental studies have shown that the avoidance inducing effect of conspicuous prey coloration increases with increasing size of pattern elements and with increasing body size. Here we use a comparative approach to test the prediction from these findings, namely that conspicuous coloration will evolve in tandem with body size. In our analysis, we use a previously published mitochondrial DNA-based phylogeny and comparative analysis of independent contrasts to examine if evolutionary shifts in color pattern have been associated with evolutionary changes in body size in aposematic poison frogs (Anura: Dendrobatidae). Information on body size (snout to vent length) and coloration were obtained from the literature. Two different measures of conspicuousness were used, one based on rankings by human observers and the other based on computer analysis of digitized photographs. The results from comparative analyses using either measure of coloration indicated that avoidance inducing coloration and body size have evolved in concert in poison frogs. Results from reconstruction of character change further indicate that the correlated evolution of size and coloration has involved changes in both directions within each of the different clades of the phylogenetic tree. This finding is consistent with the hypothesis that selection imposed by visually guided predators has promoted the evolution of larger body size in species with conspicuous coloration, or enhanced evolution of conspicuous coloration in larger species.

Objective: To compare the role of serum cholesterol in the long-term prognosis of men with a history of myocardial infarction, in men with clinical angina without myocardial infarction, and men without clinical coronary disease., Methods: In the second screening of the Primary Prevention Study in Göteborg which comprised 7100 men aged 51 to 59 years at baseline in 1974-1977, 314 men with clinical angina but no myocardial infarction at baseline were identified and 195 men who had survived a myocardial infarction for 0 to 19 years (median 3 years)., Results: Of the men without clinical coronary disease at baseline and cholesterol at or below 5.2 mmol.l-1, 2.7 per 1000 observation years died from coronary disease compared to 8.5 per 1000 of the men with serum cholesterol of 7.2 mmol.l-1 or more. Corresponding figures for men with angina was 5.5 and 31.0 per 1000 observation years, and for men with prior myocardial infarction 19.8 and 58.3, respectively, per 1000. After adjustment for age, smoking, systolic blood pressure, body mass index and diabetes the risk of coronary death in men with serum cholesterol above 7.2 mmol.l-1 compared to below 5.2 mmol.l-1 was 2.42 (1.66-3.51) in healthy men, 4.82 (1.44-16.09) in men with angina, 2.70 (0.95-7.67) in survivors of myocardial infarction, and 4.07 (1.86-8.91) in the combined group of men with either angina or prior infarction. The strongest effect was seen during the first half of the follow-up, with an adjusted relative risk for high in relation to low serum cholesterol of 8.08 (1.95-33.55) in men with preexisting coronary disease. Non-coronary deaths varied little by serum cholesterol or coronary disease status at baseline. After 16 years, 76% of the healthy men with low cholesterol and 65% of healthy men with cholesterol above 7.2 mmol.l-1 were still alive. Of the men with prior myocardial infarction, 50% in the group with low cholesterol were alive after 16 years, as compared to 21% of those with high cholesterol., Conclusion: The long-term absolute risk of death in men with coronary disease and elevated serum cholesterol is very high. Implementation of lipid-lowering strategies shown to be efficacious is important in this high-risk group.

Male Sprague-Dawley rats were treated for one month with daily intraperitoneal injections of ethanol (2 g kg-1), or saline. After this pretreatment, animals from each group were given acute doses of ethanol (2 g kg-1) or saline. Plasma amino acid concentrations and brain tyrosine, tryptophan, dopamine, 5-HT and 5-HIAA concentrations were measured in samples collected 1 h after the injections. Acute administration of ethanol induced a dramatic fall in the concentrations of 18 out of 20 plasma amino acids in animals pretreated with saline. In animals chronically pretreated with ethanol this decrease was much smaller. Furthermore, the decrease was significantly lower for 6 of the measured amino acids in the chronic ethanol group compared with the saline-treated control group. Tolerance to the plasma amino acid decreasing effect of ethanol had thus developed. This acquired tolerance might be explained by both pharmacokinetic and pharmacodynamic mechanisms. Chronic administration of ethanol induced increased concentrations of tyrosine and dopamine in the brain, probably due to increased transport of tyrosine into the brain caused by an increase in the ratio of tyrosine to large neutral amino acids in plasma.

Male rats were given three different doses of ethanol in i.p. injections (0.66, 1.33 and 2.00 g kg-1). A dose-dependent decrease in the concentrations of most plasma amino acids was observed. For the total amino acid concentration this decrease was 5, 16 and 22%, respectively, compared with a saline-treated control group. It has previously been suggested that the oxidation of ethanol plays an important role in the amino acid decreasing effect of ethanol. In this study the lowest dose used (0.66 g kg-1) was calculated to be high enough to keep the enzyme systems involved in ethanol oxidation saturated during the 60 min course of the experiment. The observation that the ethanol-induced decrease in plasma amino acid levels was more pronounced with higher ethanol doses indicates that not only the oxidation of ethanol but also ethanol itself is important in the effect of ethanol on plasma amino acid concentrations.