Analyzing growth trajectories.

Growth trajectories play a central role in life course epidemiology, often providing fundamental indicators of prenatal or childhood development, as well as an array of potential determinants of adult health outcomes. Statistical methods for the analysis of growth trajectories have been widely studied, but many challenging problems remain. Repeated measurements of length, weight and head circumference, for example, may be available on most subjects in a study, but usually only sparse temporal sampling of such variables is feasible. It can thus be challenging to gain a detailed understanding of growth patterns, and smoothing techniques are inevitably needed. Moreover, the problem is exacerbated by the presence of large fluctuations in growth velocity during early infancy, and high variability between subjects. Existing approaches, however, can be inflexible because of a reliance on parametric models, require computationally intensive methods that are unsuitable for exploratory analyses, or are only capable of examining each variable separately. This article proposes some new nonparametric approaches to analyzing sparse data on growth trajectories, with flexibility and ease of implementation being key features. The methods are illustrated using data on participants in the Collaborative Perinatal Project.

Congenital malformations in experimental diabetic pregnancy: aetiology and antioxidative treatment. Minireview based on a doctoral thesis.

Diabetes mellitus in pregnancy causes congenital malformations in the offspring. The aim of this work was to characterize biochemical and morphologic anomalies in the conceptus of an animal model of diabetic pregnancy. In addition, a preventive treatment against diabetes-induced dysmorphogenesis was developed. Congenital cataract was often found in the offspring of diabetic rats. The fetal lenses had increased water accumulation, sorbitol concentration and aldose reductase activity compared to control lenses. The results suggest that the cataracts form via osmotic attraction of water due to sorbitol accumulation in the fetal lens. Another set of malformations, with possible neural crest cell origin, occurred frequently in offspring of diabetic rats. These included low set ears, micrognathia, hypoplasia of the thymus, thyroid and parathyroid glands, as well as anomalies of the heart and great vessels. Furthermore, diabetes caused intrauterine death and resorptions more frequently in the late part of gestation. When the pregnant diabetic rats were treated with the antioxidants butylated hydroxytoluene, vitamin E or vitamin C, the occurrence of gross malformations was reduced from approximately 25% to less than 8%, and late resorptions from 17% to 7%. This suggests that an abnormal handling of reactive oxygen species (ROS) is involved in diabetes-induced dysmorphogenesis in vivo. Indeed, an increased concentration of lipid peroxides, indicating damage caused by ROS, was found in fetuses of diabetes rats. In addition, embryos of diabetic rats had low concentrations of the antioxidant vitamin E compared to control embryos. These biochemical alterations were normalized by vitamin E treatment of the pregnant diabetic rats. The antioxidants are likely to have prevented ROS injury in the embryos of the diabetic rats, in particular in the neural crest cells, thereby normalizing embryonic development. These results provide a rationale for developing new anti-teratogenic treatments for pregnant women with diabetes mellitus.

High prevalence of human hydatid disease (echinococcosis) in communities in northern Israel: epidemiologic studies in the town of Yirka.

The resurgence of hydatid disease in communities in northern Israel led to epidemiologic studies in 1988 in the town of Yirka, a semirural Druze community of 8200 persons. In domestic animal surveys, 8% of 63 dogs tested after an arecoline purge and 10% of 255 sheep at the abattoir were found to be infected. In a randomized serosurvey of 758 persons using the indirect hemagglutination test (positive titer greater than or equal to 1:512), 9% (68) had a titer greater than or equal to 1:64, 2.2% had a titer greater than or equal to 1:256 and 0.9% had a titer greater than or equal to 1:512. Of those with titers greater than or equal to 1:64, 59 were evaluated by abdominal sonography and chest x-ray: 6 of the 59 were found to be persons who previously had had a liver or a lung hydatid cyst surgically removed; 6 other persons (5 with negative indirect hemagglutination titers) were found to have a newly detected asymptomatic cyst. Of the latter group, hydatid confirmation was subsequently obtained by surgery for 2 persons and by arc 5 and/or immunoblot assay for 4 persons. Thus, the cumulative percentage of confirmed present or recent past hydatid infections was 12/758 (1.6%) leading to an extrapolated rate of 1583/100,000 persons. This ranks Yirka among the highly endemic areas for hydatidosis worldwide. The study also showed that imaging methods were more sensitive than the indirect hemagglutination serologic test for conducting a prevalence survey.

A systemic health care quality service program.

This article describes a systemic quality service program implemented in a community hospital as an initial component of a total quality approach. The program interventions are based on consumer research and principles that have been effective in producing organizational change and enhancing worker performance. The description of the program is organized around six change and performance-enhancement principles: (1) establishing the importance of the performance, (2) specifying the expected performance, (3) ensuring the ability to carry out the performance, (4) accurately measuring the performance, (5) providing consequences, and (6) addressing systemic blocks to effective performance. Evaluative data are presented, indicating enhanced performance in the critical areas of documented resolutions to problems and reduced response time to problems.