Epidemiology of adult congenital heart disease: demographic variations worldwide

The population of adults with a congenital heart defect (CHD) is increasing, due to improved survival after cardiac surgery. To accommodate the specialised care for these patients, a profound interest in the epidemiology of CHD is required. The exact size of the current population of adults with CHD is unknown, but the best available evidence suggests that currently overall prevalence of CHD in the adult population is about 3000 per million. Regional differences in CHD prevalence have been described, due to both variations in incidence and in mortality. Knowledge of demographic variations of CHD may lead to new aetiological insights and may be useful for preventive therapies. Socioeconomic status, education, urbanisation, climatological factors, ethnicity and patient-related factors, such as comorbidity, lifestyle and healthcare-seeking behaviour, may play a role in CHD incidence and mortality. The higher risk of several major cardiac outcomes in males with CHD might well explain at least partly the increased mortality rate in men. Regional differences in quality of life among CHD patients have been reported and although methodological differences may play a role, sociocultural differences warrant further attention. Socioeconomic outcomes in CHD patients, such as lower education, more unemployment and less relationships, might have a different impact on quality of life in different cultures. To gain more insight into demographic differences around the world large international multicentre studies on the epidemiology of CHD are needed.     

Further Studies on the Effect of Human Effusions on the Mitotic Index of Mammalian Cells Grown in Cell Culture

Employing L and HeLa cells grown as a monolayer on coverslips in Leighton tubes, 19 human effusions were screened for the presence of growth-promoting factors. The screening test consisted in recording from microscopic studies the percentage of cells in division after incubation for 36 hours in the test medium, with the last 12 hours of incubation in the presence of a mitostatic agent. The effusions were diluted to one-third strength with Hanks'' balanced salt solution and were tested in triplicate; a minimum of 500 cells were counted for each replicate. All effusions possessed growth-promoting activity. The results suggested that effusions from patients with malignant disease do not differ in growth-promoting activity in cell culture from effusions obtained from patients with non-malignant disorders.     

Peripheral injection of DNS-RFa, a FMRFa agonist, suppresses morphine-induced analgesia in rats

The present results demonstrate an antagonistic effect of DNS-RFa on morphine-induced analgesia in rats. This confirms previous evidence presented by others on the effects of FMRFa-related peptides when applied centrally. Unlike these peptides, however, it is shown here that DNS-RFa is effective upon peripheral injection. The effects of DNS-RFa on morphine-induced analgesia were dose-dependent (ED50 = 0.5 mg/kg). DNS-RFa alone (5 mg/kg) did not affect the control level of nociception. Peripheral injection of FMRFa (5 mg/kg) did not affect morphine-induced analgesia. DNS-RFa defines the minimal configuration to activate neuronal FMRFa receptors in the pond snail. The present report suggests also that in vertebrates the Arg-Phe-NH2 sequence is essential and that DNS-RFa readily penetrates the blood-brain barrier.     

Estimation of prediction error variances via Monte Carlo sampling methods using different formulations of the prediction error variance

Calculation of the exact prediction error variance covariance matrix is often computationally too demanding, which limits its application in REML algorithms, the calculation of accuracies of estimated breeding values and the control of variance of response to selection. Alternatively Monte Carlo sampling can be used to calculate approximations of the prediction error variance, which converge to the true values if enough samples are used. However, in practical situations the number of samples, which are computationally feasible, is limited. The objective of this study was to compare the convergence rate of different formulations of the prediction error variance calculated using Monte Carlo sampling. Four of these formulations were published, four were corresponding alternative versions, and two were derived as part of this study. The different formulations had different convergence rates and these were shown to depend on the number of samples and on the level of prediction error variance. Four formulations were competitive and these made use of information on either the variance of the estimated breeding value and on the variance of the true breeding value minus the estimated breeding value or on the covariance between the true and estimated breeding values.     

The mechanism of aggregate formation by Selenomonas ruminantium

Summary The mechanism of granule formation by Selenomonas ruminantium was investigated. A basic protein has been isolated from the lysate of S. ruminantium which triggers cluster formation (small aggregates of 20–100 cells) of suspended cells. Evidence is presented that these basic proteins were of ribosomal origin. It is suggested that ribosomes are released into the culture broth by lysis and that the associated basic proteins are subsequently dissociated by high monovalent cation concentrations. It was found that these positively charged basic proteins interact with the negatively charged lipopolysaccharide of the organism to form the clusters. Adding lysate to suspended cells, followed by lowering of the pH from 5.8 to 4.5 also induced clustering. At dilution rates exceeding the maximum growth rate clusters were retained in anaerobic gas-lift reactors and grew into granules (1–3 mm). It is postulated that granules evolve from clusters. Within the clusters, lysis and a low pH are induced due to diffusion limitations. As a consequence dividing cells are entrapped within the clusters, resulting in growth.