Veertig jaar epidemiologie aan de Erasmus Universiteit 1969-2009

Waarschijnlijk telt geen land ter wereld per hoofd van de bevolking zoveel epidemiologen als Nederland. De Nederlandse Vereniging van Epidemiologen is een van de grootste in Europa. Elke maand verschijnen in de beste internationale wetenschappelijke tijdschriften resultaten van Nederlands epidemiologisch onderzoek. En het zijn artikelen die ertoe doen. In de top 25 van meest geciteerde Nederlands onderzoekers zijn er alleen al zes gelieerd aan het ERGO-onderzoek: een cohort van inmiddels ruim 15.000 Rotterdammers dat nu al bijna 20 jaar loopt. Om kort te gaan: epidemiologie is hot in Holland. Deze bundel bevat afscheidsredes en oraties uit de afgelopen veertig jaar, Tot slot bevat dit boek een opsomming van promovendi die vanuit de afdeling Epidemiologie hun proefschrift verdedigden aan de Erasmus Universiteit, en van alle medewerkers, oud-medewerkers en gasten met een formele aanstelling bij de afdeling Epidemiologie

A biomechanical model of anther opening reveals the roles of dehydration and secondary thickening

Understanding the processes that underlie pollen release is a prime target for controlling fertility to enable selective breeding and the efficient production of hybrid crops. Pollen release requires anther opening, which involves changes in the biomechanical properties of the anther wall. In this research, we develop and use a mathematical model to understand how these biomechanical processes lead to anther opening

Prolonged hypothyroidism severely reduces ovarian follicular reserve in adult rats

Background There is substantial evidence both in humans and in animals that a prolonged reduction in plasma thyroid hormone concentration leads to reproductive problems, including disturbed folliculogenesis, impaired ovulation and fertilization rates, miscarriage and pregnancy complications. The objective of the present study is to examine the consequences of chronic hypothyroidism, induced in adulthood, for the size of the ovarian follicle pool. In order to investigate this, adult female rats were provided either a control or an iodide deficient diet in combination with perchlorate supplementation to inhibit iodide uptake by the thyroid. Sixteen weeks later animals were sacrificed. Blood was collected for hormone analyses and ovaries were evaluated histologically. Results At the time of sacrifice, plasma thyroid-stimulating hormone concentrations were 20- to 40-fold increased, thyroxine concentrations were negligible while tri-iothyronin concentrations were decreased by 40% in the hypothyroid group, confirming that the animals were hypothyroid. Primordial, primary and preantral follicle numbers were significantly lower in the hypothyroid ovaries compared to the euthyroid controls, while a downward trend in antral follicle and corpora lutea numbers was observed. Surprisingly the percentage of atretic follicles was not significantly different between the two groups, suggesting that the reduced preantral and antral follicle numbers were presumably not the consequence of increased degeneration of these follicle types in the hypothyroid group. Plasma anti-Müllerian hormone (AMH) levels showed a significant correlation with the growing follicle population represented by the total ovarian number of primary, preantral and antral follicles, suggesting that also under hypothyroid conditions AMH can serve as a surrogate marker to assess the growing ovarian follicle population. Conclusions The induction of a chronic hypothyroid condition in adult female rats negatively affects the ovarian follicular reserve and the size of the growing follicle population, which may impact fertility

Dual Effect on Adult-Type Leydig Cell and Sertoli Cell Development

Transient neonatal 6-propyl-2-thiouracil (PTU) induced hypothyroidism affects Leydig and Sertoli cell numbers in the developing testis, resulting in increased adult testis size. The hypothyroid condition was thought to be responsible, an assumption questioned by studies showing that uninterrupted fetal/postnatal hypothyroidism did not affect adult testis size. Here, we investigated effects of transient hypothyroidism on Leydig and Sertoli cell development, employing a perinatal iodide-deficient diet in combination with sodium perchlorate. This hypothyroidism inducing diet was continued until days 1, 7, 14, or 28 postpartum (pp) respectively, when the rats were switched to a euthyroid diet and followed up to adulthood. Continuous euthyroid and hypothyroid, and neonatal PTU-treated rats switched to the euthyroid diet at 28 days pp, were included for comparison. No effects on formation of the adult-type Leydig cell population or on Sertoli cell proliferation and differentiation were observed when the diet switched at/or before day 14 pp. However, when the diet was discontinued at day 28 pp, Leydig cell development was delayed similarly to what was observed in chronic hypothyroid rats. Surprisingly, Sertoli cell proliferation was 6- to 8-fold increased 2 days after the diet switch and remained elevated the next days. In adulthood, Sertoli cell number per seminiferous tubule cross-section and consequently testis weight was increased in this group. These observations implicate that increased adult testis size in transiently hypothyroid rats is not caused by the hypothyroid condition per se, but originates from augmented Sertoli cell proliferation as a consequence of rapid normalization of thyroid hormone concentrations

Me, my selfie, and I:the relations between selfie behaviors, body image, self-objectification, and self-esteem in young women

Due to the enormous popularity of social networking sites (SNSs), online and offline social lives seem inextricably linked, which raises concerns for how SNS use relates to psychological health. Similarly, the omnipresence of selfies on SNSs—a form of appearance-related exposure—raises concerns regarding psychological health. This study aimed to investigate the relationships between body image, self-objectification, self-esteem, and various selfie behaviors among young women (N = 179). We hypothesized that a worsened body image (i.e., higher body dissatisfaction or lower body appreciation), higher levels of self-objectification, and lower self-esteem would precede greater engagement in selfie behaviors. Structural equation modeling showed that body appreciation is associated with greater engagement in selfie selection and deliberate posting, and that self-objectification is related to greater engagement in all selfie behaviors assessed. In support of our proposed model, a reversed model was also tested that showed poorer results. These findings suggest that body image may serve not only as an outcome of SNS use but also as a motive preceding selfie behaviors

Me, My Selfie, and I:The Relations Between Selfie Behaviors, Body Image, Self-Objectification, and Self-Esteem in Young Women

Due to the enormous popularity of social networking sites (SNSs), online and offline social lives seem inextricably linked, which raises concerns for how SNS use relates to psychological health. Similarly, the omnipresence of selfies on SNSs-a form of appearance-related exposure-raises concerns regarding psychological health. This study aimed to investigate the relationships between body image, self-objectification, self-esteem, and various selfie behaviors among young women (N = 179). We hypothesized that a worsened body image (i.e., higher body dissatisfaction or lower body appreciation), higher levels of self-objectification, and lower self-esteem would precede greater engagement in selfie behaviors. Structural equation modeling showed that body appreciation is associated with greater engagement in selfie selection and deliberate posting, and that self-objectification is related to greater engagement in all selfie behaviors assessed. In support of our proposed model, a reversed model was also tested that showed poorer results. These findings suggest that body image may serve not only as an outcome of SNS use but also as a motive preceding selfie behaviors

Інтеграційні процеси в паливно-енергетичному комплексі як фактор забезпечення екологічної безпеки

Challenge tests stress homeostasis and may reveal deviations in health that remain masked under unchallenged conditions. Ideally, challenge tests are non-invasive and applicable in an early phase of an animal experiment. Oxygen restriction (OxR; based on ambient, mild normobaric hypoxia) is a non-invasive challenge test that measures the flexibility to adapt metabolism. Metabolic inflexibility is one of the hallmarks of the metabolic syndrome. To test whether OxR can be used to reveal early diet-induced health effects, we exposed mice to a low-fat (LF) or high-fat (HF) diet for only 5 days. The response to OxR was assessed by calorimetric measurements, followed by analysis of gene expression in liver and epididymal white adipose tissue (eWAT) and serum markers for e.g. protein glycation and oxidation. Although HF feeding increased body weight, HF and LF mice did not differ in indirect calorimetric values under normoxic conditions and in a fasting state. Exposure to OxR; however, increased oxygen consumption and lipid oxidation in HF mice versus LF mice. Furthermore, OxR induced gluconeogenesis and an antioxidant response in the liver of HF mice, whereas it induced de novo lipogenesis and an antioxidant response in eWAT of LF mice, indicating that HF and LF mice differed in their adaptation to OxR. OxR also increased serum markers of protein glycation and oxidation in HF mice, whereas these changes were absent in LF mice. Cumulatively, OxR is a promising new method to test food products on potential beneficial effects for human health

Metabolic effects of the dietary monosaccharides fructose, fructose-glucose, or glucose in mice fed a starch-containing moderate high-fat diet

Fructose consumption has been linked to obesity and increased hepatic de novo lipogenesis (DNL). Excessive caloric intake often confounds the results of fructose studies, and experimental diets are generally low-fat diets, not representative for westernized diets. Here, we compared the effects of dietary fructose with those of dietary glucose, in adult male and female mice on a starch-containing moderate high-fat (HF) diet. After 5 weeks fattening on a HF high-glucose (HF-G) diet, mice were stratified per sex and assigned to one of the three intervention diets for 6 weeks: HF high fructose (HF-F), HF with equimolar glucose and fructose (HF-GF), or HF-G. Bodyweight (BW) and food intake were measured weekly. Indirect calorimetry was performed on week 5; animals were sacrificed in food-deprived state on week 6. Data were analyzed within sex. BW gain was similar among animals on the HF-G, HF-GF, and HF-F diets. Cumulative food intake was slightly lower in HF-F animals (both sexes). However, energy expenditure was not affected, or were circulating insulin and glucose concentrations, and hepatic triglyceride levels at endpoint. Hepatic gene expression analysis showed only minor alterations in hexokinase and glycolysis-related expression in males, and no alterations in sugar transporters, or DNL-related enzymes. In females, no consistent alterations in hepatic or small intestine gene expression were seen. Concluding, partial or complete replacement of dietary glucose with fructose does not increase caloric intake, and does not affect BW, hepatic triglyceride levels, or insulin concentrations in male and female mice on a moderate high-fat diet.</p

BIOCLAIMS standard diet (BIOsd): a reference diet for nutritional physiology

Experimental replication is fundamental for practicing science. To reduce variability, it is essential to control sources of variation as much as possible. Diet is an important factor that can influence many processes and functional outcomes in studies performed with rodent models. This is especially true for, but not limited to, nutritional studies. To compare functional effects of different nutrients, it is important to use standardized, semi-purified diets. Here, we propose and describe a standard reference diet, the BIOCLAIMS standard diet. The diet is AIN-93 based, but further defined with dietary and experimental requirements taken into account that allow for experiments with bioactive food components and natural (non-expensive) labeling. This diet will be implemented by two European research consortia, Mitofood and BIOCLAIMS, to ensure inter-laboratory comparability

Induction of lipid oxidation by polyunsaturated fatty acids of marine origin in small intestine of mice fed a high-fat diet

Background. Dietary polyunsaturated fatty acids (PUFA), in particular the long chain marine fatty acids docosahexaenoic (DHA) and eicosapentaenoic (EPA), are linked to many health benefits in humans and in animal models. Little is known of the molecular response to DHA and EPA of the small intestine, and the potential contribution of this organ to the beneficial effects of these fatty acids. Here, we assessed gene expression changes induced by DHA and EPA in the wildtype C57BL/6J murine small intestine using whole genome microarrays and functionally characterized the most prominent biological process. Results. The main biological process affected based on gene expression analysis was lipid metabolism. Fatty acid uptake, peroxisomal and mitochondrial beta-oxidation, and omega-oxidation of fatty acids were all increased. Quantitative real time PCR, and -in a second animal experiment- intestinal fatty acid oxidation measurements confirmed significant gene expression differences and showed in a dose-dependent manner significant changes at biological functional level. Furthermore, no major changes in the expression of lipid metabolism genes were observed in the colon. Conclusion. We show that marine n-3 fatty acids regulate small intestinal gene expression and increase fatty acid oxidation. Since this organ contributes significantly to whole organism energy use, this effect on the small intestine may well contribute to the beneficial physiological effects of marine PUFAs under conditions that will normally lead to development of obesity, insulin resistance and diabete