Weak Influence (weak + influence)

Distribution by Scientific Domains


Selected Abstracts


Screening for depression and anxiety: correlates of non-response and cohort attrition in the Netherlands Study of Depression and Anxiety (NESDA)

INTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 4 2009
Willem Jan Van Der Veen
Abstract A major problem in the analysis of attrition of cohorts in studies on mental health problems is that data on those who do not participate at the outset of a study are largely unavailable. It is not known how underlying psychopathology affects the first stages of screening where non-response and selectivity are usually highest. This article presents results of one of the centres of the Netherlands Study of Depression and Anxiety (NESDA), a longitudinal study aimed at describing the long-term course and consequences of depression and anxiety disorders. The aim is to describe the different ways of attrition during the first NESDA-wave in a cohort of patients aged 18,65 years of the Registration Network Groningen and to analyse whether attrition is related to gender, age and psychopathology as recorded in general practice. The attrition of the study cohort (n = 8475) was highest during the first stages, eventually leading to a population of 169 patients only who participated in the full NESDA-programme. Probabilities of transition from one stage of the screening process to the next were regressed on selected background variables using binary logistic regression. Correlates of participation were being female and being older (>40). Psychopathology was an important variable in the formation of the initial sample cohort, but only had a weak influence on patient response to the screening questionnaire. Study design factors had a stronger impact on the changing composition of the cohort at each screening stage compared to patient factors. Copyright © 2009 John Wiley & Sons, Ltd. [source]


In vivo metabolic effects of naringenin in the ethanol consuming rat and the effect of naringenin on adipocytes in vitro

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2007
K. Szkudelska
Summary Naringenin is a bioactive flavanone involved in the inhibition of drug metabolism which exhibits antioxidant, anti-inflammatory and anticancerogenic properties and which recently appeared to be a factor mitigating the hyperlipidaemic effects in rats and rabbits. In the performed experiment, the effect of naringenin, administered intragastrically (50 mg/kg) for 2 weeks to normal and ethanol drinking rats, on insulin and leptin levels and on some metabolic parameters was investigated. Naringenin did not change the hormone levels in any group of rats. Blood glucose, triglyceride, total, esterified and free cholesterol and high-density lipoprotein-cholesterol concentrations were also unaffected by this compound. Only free fatty acids were elevated after the naringenin treatment in the water-drinking rats. In spite of unchanged glucose and insulin concentrations in blood, the tested flavanone reduced the glucose/insulin ratio in ethanol-receiving rats. Liver triglycerides, elevated due to ethanol ingestion, were partially normalized by naringenin. Other tested parameters like liver glycogen and cholesterol, muscle triglycerides and glycogen were not altered in any group of rats. The influence of naringenin (62.5, 125, 250 and 500 ,m) on basal and insulin-stimulated glucose conversion to lipids (lipogenesis) as well as on basal and epinephrine-stimulated glycerol release (lipolysis) in the isolated rat adipocytes was also tested. The basal and the stimulated lipogenesis tended to be decreased in the presence of the flavanone (250 ,m). This inhibitory effect intensified and was statistically significant at the highest concentration of naringenin. The tested compound did not evoke any effect on basal lipolysis while the epinephrine-stimulated process was limited at the highest concentration of the flavanone. Naringenin (62.5, 125, 250 and 500 ,m) had no effect on leptin secretion from the isolated rat adipocytes. Results obtained in our studies demonstrate that naringenin exerts a very weak influence on carbohydrate and lipid metabolism of normal and ethanol-consuming rats and on metabolism of isolated rat adipocytes. [source]


Sperm competition selects for increased testes mass in Australian frogs

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2002
P. G. Byrne
Game theory predicts that investment in spermatogenesis will increase with the risk and intensity of sperm competition. Widespread support for this prediction has come from comparative studies of internal fertilizing species reporting positive associations between testes mass and the probability that females mate with more than one male. Data for external fertilizers have generated conflicting results. We investigated how risk of sperm competition affects testes size in two families of Australian frogs: the Myobatrachidae and the Hylidae. We also examined effects of clutch size, egg size and oviposition location as alternative factors that might influence sperm production. Species were ranked according to probability of group spawning, and hence risk of sperm competition. Controlling for body size and phylogenetic relationships, we demonstrated that within the Myobatrachidae, the risk of sperm competition explained a significant amount of variation in testes mass. Oviposition location had a weak influence, with species ovipositing into foam having smaller testes. No significant effects of clutch size or egg size were detected. In hylids, the relationship between testes mass and risk of sperm competition was positive but not significant, again with no predictable effects related to egg size or number. These data provide an important test of sperm competition theory for externally fertilizing taxa. [source]


Environmental features influencing Carabid beetle (Coleoptera) assemblages along a recently deglaciated area in the Alpine region

ECOLOGICAL ENTOMOLOGY, Issue 6 2007
MAURO GOBBI
Abstract 1.,The spatio-temporal approach was used to evaluate the environmental features influencing carabid beetle assemblages along a chronosequence of an Italian Alpine glacier foreland. The influence of environmental variables on species richness, morphology (wing and body length), and distribution along the chronosequence was tested. 2.,Species richness was found to be a poor indicator of habitat due to weak influences by environmental variables. It seems that the neighbouring habitats of a glacier foreland are not able to determine significant changes in carabid species richness. 3.,Instead it appears that history (age since deglaciation) and habitat architecture of a glacier foreland are strongly correlated to species adaptive morphological traits, such as wing morphology and body length. Assemblages characterised by species with reduced wing size are linked to the older stages of the chronosequence, where habitat is more structured. Assemblages characterised by the largest species are linked to the younger sites near the glacier. These morphological differentiations are explained in detail. 4.,Habitat age can therefore be considered the main force determining assemblage composition. On the basis of the relationship between morphological traits and environmental variables, it seems likely that age since deglaciation is the main variable influencing habitat structure (primary effect) on the Forni foreland. The strong relationship between carabid assemblages and habitat type indicates that site age has but a secondary effect on carabid assemblages. This may be utilised to interpret potential changes in assemblages linked to future glacier retreat. [source]


Spatial and temporal variations in the timing of leaf replacement in a Quercus cornelius-mulleri population

JOURNAL OF VEGETATION SCIENCE, Issue 6 2003
Martin L. Cody
Nixon & Steele (1981) Abstract. The phenology of spring leaf replacement was studied in a population of 46 evergreen scrub oaks (Quercus cornelius-mulleri) at the edge of the Mojave Desert in each of five years over the period 1990,2001. The oaks occupied a site that spanned rocky slopes to sandy bajadas. The site receives variable annual rainfall (estimated 12-yr average 195 mm; range in study years 67,706 mm). The spatial coordinates of all individuals were recorded, and in April, when leaf replacement was underway, individual replacement phenologies were assessed. Shrub sizes were recorded in three separate years, and in 2001 water potentials were measured. Individuals vary greatly in their timing of leaf replacement within years, and also between years. Many individuals with an early phenology one year are significantly later in the following year, and vice versa. While we detected weak influences on leaf replacement phenology due to shrub size, position within the site, and a genetic component, stronger influences were attributable to the phenology of the shrub in prior years, and to the phenology of neighbours within years. Neighbouring individuals that are close and/or large are significantly disparate in phenology, with one early and the other late. A potential mechanism of local resource depletion associated with costs to an early phenology is discussed. [source]