463 research outputs found
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
Downregulation of Fzd6 and Cthrc1 and upregulation of olfactory receptors and protocadherins by dietary beta-carotene in lungs of Bcmo1-/- mice.
An ongoing controversy exists on beneficial versus harmful effects of high beta-carotene (BC) intake, especially for the lung. To elucidate potential mechanisms, we studied effects of BC on lung gene expression. We used a beta-carotene 15,15'-monooxygenase 1 (Bcmo1) knockout mouse (Bcmo1-/-) model, unable to convert BC to retinoids, and wild-type mice (Bcmo1+/+) mice to dissect the effects of intact BC from effects of BC metabolites. As expected, BC supplementation resulted in a higher BC accumulation in lungs of Bcmo1-/- mice than in lungs of Bcmo1+/+ mice. Whole mouse genome transcriptome analysis on lung tissue revealed that more genes were regulated in Bcmo1-/- mice than Bcmo1+/+ mice upon BC supplementation. Frizzled homolog 6 (Fzd6) and collagen triple helix repeat containing 1 (Cthrc1) were significantly downregulated (fold changes -2.99 and -2.60, respectively, false discovery rate <0.05) by BC in Bcmo1-/-. Moreover, many olfactory receptors and many members of the protocadherin family were upregulated. Since both olfactory receptors and protocadherins have an important function in sensory nerves and Fzd6 and Cthrc1 are important in stem cell development, we hypothesize that BC might have an effect on the highly innervated pulmonary neuroendocrine cell (PNEC) cluster. PNECs are highly associated with sensory nerves and are important cells in the control of stem cells. A role for BC in the innervated PNEC cluster might be of particular importance in smoke-induced carcinogenesis since PNEC-derived lung cancer is highly associated with tobacco smoke
Downregulation of Fzd6 and Cthrc1 and upregulation of olfactory receptors and protocadherins by dietary beta-carotene in lungs of Bcmo1-/- mice.
An ongoing controversy exists on beneficial versus harmful effects of high beta-carotene (BC) intake, especially for the lung. To elucidate potential mechanisms, we studied effects of BC on lung gene expression. We used a beta-carotene 15,15'-monooxygenase 1 (Bcmo1) knockout mouse (Bcmo1-/-) model, unable to convert BC to retinoids, and wild-type mice (Bcmo1+/+) mice to dissect the effects of intact BC from effects of BC metabolites. As expected, BC supplementation resulted in a higher BC accumulation in lungs of Bcmo1-/- mice than in lungs of Bcmo1+/+ mice. Whole mouse genome transcriptome analysis on lung tissue revealed that more genes were regulated in Bcmo1-/- mice than Bcmo1+/+ mice upon BC supplementation. Frizzled homolog 6 (Fzd6) and collagen triple helix repeat containing 1 (Cthrc1) were significantly downregulated (fold changes -2.99 and -2.60, respectively, false discovery rate <0.05) by BC in Bcmo1-/-. Moreover, many olfactory receptors and many members of the protocadherin family were upregulated. Since both olfactory receptors and protocadherins have an important function in sensory nerves and Fzd6 and Cthrc1 are important in stem cell development, we hypothesize that BC might have an effect on the highly innervated pulmonary neuroendocrine cell (PNEC) cluster. PNECs are highly associated with sensory nerves and are important cells in the control of stem cells. A role for BC in the innervated PNEC cluster might be of particular importance in smoke-induced carcinogenesis since PNEC-derived lung cancer is highly associated with tobacco smoke
Deconjugation Kinetics of Glucuronidated Phase II Flavonoid Metabolites by B-glucuronidase from Neutrophils
Flavonoids are inactivated by phase II metabolism and occur in the body as glucuronides. Mammalian ß-glucuronidase released from neutrophils at inflammatory sites may be able to deconjugate and thus activate flavonoid glucuronides. We have studied deconjugation kinetics and pH optimum for four sources of ß-glucuronidase (human neutrophil, human recombinant, myeloid PLB-985 cells, Helix pomatia) with five flavonoid glucuronides (quercetin-3-glucuronide, quercetin-3'-glucuronide, quercetin-4'-glucuronide, quercetin-7-glucuronide, 3'-methylquercetin-3-glucuronide), 4-methylumbelliferyl-ß-D-glucuronide, and para-nitrophenol-glucuronide. All substrate-enzyme combinations tested exhibited first order kinetics. The optimum pH for hydrolysis was between 3.5-5, with appreciable hydrolysis activities up to pH 5.5. At pH 4, the Km ranged 44-fold from 22 µM for quercetin-4'-glucuronide with Helix pomatia ß-glucuronidase, to 981 µM for para-nitrophenol-glucuronide with recombinant ß-glucuronidase. Vmax (range: 0.735-24.012 µmol·min-1·unit-1 [1 unit is defined as the release of 1 µM 4-methylumbelliferyl-ß-D-glucuronide per min]) and the reaction rate constants at low substrate concentrations (k) (range: 0.002-0.062 min-1·(unit/L)-1 were similar for all substrates-enzyme combinations tested. In conclusion, we show that ß-glucuronidase from four different sources, including human neutrophils, is able to deconjugate flavonoid glucuronides and non-flavonoid substrates at fairly similar kinetic rates. At inflammatory sites in vivo the pH, neutrophil and flavonoid glucuronide concentrations seem favorable for deconjugation. However, it remains to be confirmed whether this is actually the case
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-MĂĽllerian 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
Ileal Mucosal and Fecal Pancreatitis Associated Protein Levels Reflect Severity of Salmonella Inflection in Rats
Background Microbial infections induce ileal pancreatitis-associated protein/regenerating gene III (PAP/RegIII) mRNA expression. Despite increasing interest, little is known about the PAP/RegIII protein. Therefore, ileal mucosal PAP/RegIII protein expression, localization, and fecal excretion were studied in rats upon Salmonella infection. Results Salmonella infection increased ileal mucosal PAP/RegIII protein levels in enterocytes located at the crypt-villus junction. Increased colonization and translocation of Salmonella was associated with higher ileal mucosal PAP/RegIII levels and secretion of this protein in feces. Conclusions PAP/RegIII protein is increased in enterocytes of the ileal mucosa during Salmonella infection and is associated with infection severity. PAP/RegIII is excreted in feces and might be used as a new and non-invasive infection marke
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
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
- …