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PubMed2006

Is dietary intake able to explain differences in body fatness in children and adolescents?

Obesity is the result of an imbalance between energy intake and energy expenditure. Controversial information exists about what are the strongest energy balance aspects influencing body fatness. This article is focused on food consumption facts that could be related to the risk of being obese in children and adolescents. It reviews whether energy intake, macronutrient composition of diet, eating patterns or other dietary intake factors are able to explain differences in body composition when obesity has been already developed or even in subjects at risk to become obese. There is not enough evidence to clarify the importance of diet on overweight children and adolescents, and conclusions derived are somewhat controversial. Cross-sectional and longitudinal studies do not show clear relationships between energy intake or food composition and body fatness. To find relations between dietary factors and childhood obesity perhaps eating patterns or different types of foods must be considered: meal patterns and meal frequency, snacking and beverage consumption, fast food intake, portion sizes, etc. There is no clear association between different aspects of dietary intake and the development of obesity in children and adolescents. Longitudinal and experimental studies are needed in the future.

Adolescent↗

PubMed2005

Using social cognitive theory to explain consumers' behavioral intentions in response to direct-to-consumer prescription drug advertising.

BACKGROUND: Previous research describing consumers' communication behaviors in response to direct-to-consumer advertising (DTCA) suggests a social cognitive rationale to explain DTCA-related communication behavior. OBJECTIVE: Guided by social cognitive theory, the objective of this study was to explore outcome expectancy and self-efficacy beliefs as predictors of individuals' intentions to communicate with their physicians about an advertised drug. METHODS: One hundred and seven female college students completed a questionnaire, read an advertisement for an oral contraceptive drug, and completed a second questionnaire. The questionnaires assessed participants' self-efficacy and outcome expectancy beliefs, intended communication behavior, and demographic information. RESULTS: Pearson product-moment correlation analyses showed that outcome expectancy (r=0.75, P<.01) and self-efficacy (r=0.21, P<.05) beliefs were associated positively with intentions to communicate with physicians in response to DTCA. However, ordinary least squares regression analyses revealed that only outcome expectancy beliefs predicted intended communication behavior (B=1.56, P<.01). Results also showed that participants had a relatively greater likelihood of requesting information about, than requesting a prescription for, the advertised drug [t(106)=14.75, P<.01]. CONCLUSIONS: The results identify cognitive factors that guide consumers' plans for interacting with physicians in response to DTCA. Health care providers can use these results to guide communication with patients regarding DTCA and meet patients' drug-related informational expectations.

Adolescent↗

PubMed2005

Explaining variation in the premorbid adjustment of schizophrenia patients: the role of season of birth and family history.

UNLABELLED: Several studies have shown that patients with schizophrenia are more likely to be born in the winter and early spring than at any other time of the year. Furthermore, some studies have reported that winter-born patients differ from non-winter-born patients in terms of risk factors, symptoms, sensory abnormalities and brain morphology. Associations between season of birth and premorbid adjustment (PMA), however, are still unclear. OBJECTIVE: The main purpose of this study was to determine whether winter-born and non-winter-born schizophrenia patients differ in terms of PMA and to examine how family history of schizophrenia-spectrum disorders may influence the association. METHOD: Data on four PMA dimensions (attention, internalizing, externalizing and social problems) and family history were gathered from 37 schizophrenia patients (26 males and 11 females) and their mothers. RESULTS: Non-winter-birth and a positive family history of schizophrenia-spectrum disorders were associated with worse PMA. Results suggest that, although no significant interaction was found, season of birth and family history appear to work together in explaining distinct dimensions of PMA.

Adolescent↗

PubMed2004

'It might happen or it might not': how patients with multiple sclerosis explain their perception of prognostic risk.

This qualitative study aimed to examine risk perception and seriousness of wheelchair dependence in patients with multiple sclerosis. Perceived absolute risk and perceived seriousness were assessed for 2-year, 10-year and lifetime prognosis of wheelchair dependence using visual analogue scales (VAS). In semi-structured interviews, patients (n = 85) were asked to elucidate these VAS scores. Explaining perceived absolute risk, patients mentioned disease-related factors as well as psychological factors. Uncertainty about future disease progression was a predominant factor for all patients, even those with low and high perceptions of risk. Wheelchair dependence was perceived as a serious outcome primarily because of its possible implications, such as loss of independence. When perceptions of 2-year, 10-year and the lifetime prospect of wheelchair dependence were compared, it was found that patients discriminated in their perception of absolute risk, but less in that of seriousness. Comparison of quantitative and qualitative assessments indicated good construct validity for perception of the absolute risk and seriousness of wheelchair dependence.

Adult↗

PubMed2005

Explaining educational-related inequalities in health: Mediation and moderator models.

This paper studies how education and certain lifestyle factors affect people's self-reported health. In addition to the assessment of the effects of education and lifestyle, the study contrasts two models of explaining educational-related health inequalities: the mediation model and the moderator model. The mediation model posits that well-educated people's better health, as compared to the poorly educated, is caused by their more 'healthy' lifestyles. The moderator model suggests, by contrast, that the effects of the lifestyle variables on health are dependent upon educational level. Several analyses are carried out on two large data sets comprising of middle-aged men and women in two Norwegian counties, Rogaland and Nordland. Two main findings are presented: (1) Both education and lifestyle factors have the expected effects on health. (2) The results do not permit a clear-cut conclusion as to which of the two models of educational-related health inequalities should be preferred: whereas the results support the mediation model in the data from Rogaland, the moderator model is partially supported in the Nordland data.

Adult↗

PubMed2006

What explains the association between neighborhood-level income inequality and the risk of fatal overdose in New York City?

Accidental drug overdose is a substantial cause of mortality for drug users. Using a multilevel case-control study we previously have shown that neighborhood-level income inequality may be an important determinant of overdose death independent of individual-level factors. Here we hypothesized that the level of environmental disorder, the level of police activity, and the quality of the built environment in a neighborhood mediate this association. Data from the New York City (NYC) Mayor's Management Report, the NYC Police Department, and the NYC Housing and Vacancy Survey were used to define constructs for the level of environmental disorder, the level of police activity and the quality of the built environment, respectively. In multivariable models the odds of death due to drug overdose in neighborhoods in the top decile of income inequality compared to the most equitable neighborhoods decreased from 1.63 to 1.12 when adjusting for the three potential mediators. Path analyses show that the association between income inequality and the rate of drug overdose mortality was primarily explained by an indirect effect through the level of environmental disorder and the quality of the built environment in a neighborhood. Implications of these findings for the reduction of drug overdose mortality associated with the distribution of income are discussed.

Adolescent↗

PubMed2005

Dissimilarities in sows' ovarian status at the insemination time could explain differences in fertility between farms when frozen-thawed semen is used.

Deep intrauterine insemination (DUI) offers a suitable alternative for the commercial use of frozen-thawed boar semen. The present study evaluated how the ovarian status at DUIs of frozen-thawed spermatozoa (1 x 10(9) spz/dose, two DUIs, 30-31 and 36-37 h after detection of oestrus) in 179 sows would explain differences in fertility between two farms with similar, but not equal, reproductive management (experiment 1). A further experiment investigated whether an increase in sperm number per AI-dose (1 versus 2 x 10(9) spz/dose, two DUIs, 30-31 and 36-37 h after detection of oestrus, on 228 sows) could minimize this effect (experiment 2). Ovaries were checked by transrectal ultrasonography at the time of DUI and sows were classified into three categories: F-: ovarian pre-ovulatory follicles were visible during two examinations; O-: ovulation visible during one examination; and C-sows: corpora hemorragica visible during the two examinations. Overall farrowing rates differed (P < 0.01) between farms (70.1 versus 51.2%, farms A and B, respectively). Distribution of sows among ultrasonography categories also differed (P < 0.05) between farms (17.5, 72.2 and 10.3% were classified as F-, O- and C-sows in farm A, versus 40.2, 29.3 and 30.5% in farm B). Nevertheless, farrowing rates and litter sizes within categories did not vary between farms (P > 0.05). In addition, a two-fold increase in the number of spermatozoa per DUI improved (P < 0.05) fertility in F- and C-sows, but not in O-sows. In conclusion, the interval DUI-to-ovulation provides a major explanation for fertility differences between farms when frozen-thawed spermatozoa are used.

Animals↗

PubMed2004

How much expression divergence after yeast gene duplication could be explained by regulatory motif evolution?

We used the yeast genome sequences of gene families, microarray profiles and regulatory motif data to test the current wisdom that there is a strong correlation between regulatory motif structure and gene expression profile. Our results suggest that duplicate genes tend to be co-expressed but the correlation between motif content and expression similarity is generally poor, only approximately 2-3% of expression variation can be explained by the motif divergence. Our observations suggest that, in addition to the cis-regulatory motif structure in the upstream region of the gene, multiple trans-acting factors in the gene network can influence the pattern of gene expression significantly.

Evolution, Molecular↗

PubMed2005

Microeconomic principles explain an optimal genome size in bacteria.

Bacteria can clearly enhance their survival by expanding their genetic repertoire. However, the tight packing of the bacterial genome and the fact that the most evolved species do not necessarily have the biggest genomes suggest there are other evolutionary factors limiting their genome expansion. To clarify these restrictions on size, we studied those protein families contributing most significantly to bacterial-genome complexity. We found that all bacteria apply the same basic and ancestral 'molecular technology' to optimize their reproductive efficiency. The same microeconomics principles that define the optimum size in a factory can also explain the existence of a statistical optimum in bacterial genome size. This optimum is reached when the bacterial genome obtains the maximum metabolic complexity (revenue) for minimal regulatory genes (logistic cost).

Bacteria↗

PubMed2004

A model to explain the origin of a parasite sex-specific population structure.

A discrete time model was built to understand the origin of the sex-specific population structure of the human blood fluke, Schistosoma mansoni. We have estimated both male/female individual ratio and male/female genotype ratio of this parasite taking into account all the experimental published values on differential male and female life-history traits all along the life cycle. We considered in our model male and female life-history traits when both separated and together. The model showed that both male/female individual ratio and male/female genotype ratio of S. mansoni adults are biased toward males in each combination. This bias was more important in male/female genotype ratio than in the male/female individual ratio for the same initial values of cercarial development success. This model could explain the sex specific population structure of this parasite. Firstly, we showed that the male-biased individual ratio finds its origin in the vertebrate host. Secondly, we showed that the male-biased genotype ratio originates prior to any interrelationship between adult worms and could generate by itself a sex-specific genetic structure.

Animals↗

PubMed2005

Gene expression signatures in neutrophils exposed to glucocorticoids: a new paradigm to help explain "neutrophil dysfunction" in parturient dairy cows.

Neutrophils are the first line of immunity against most pathogens that infect cattle. These normally short-lived white blood cells develop from myeloid-lineage cells in bone marrow. Upon maturation, bone marrow neutrophils are released into the circulation where they marginate on inflamed blood vessel endothelial cells and migrate through them into the area of infection. Once migrated, neutrophils do not reenter the circulation, but rather, perform their bactericidal functions and die by apoptosis in the tissue. The cytokine and hormonal milieu of the blood and extracellular tissue fluid can influence neutrophil development and immunity-related activities, but the molecular basis of these phenotypic changes and physiological benefits or drawbacks of them are poorly understood. In the current paper, we review new gene expression information that resulted from two of our functional genomics studies designed to evaluate effects of glucocorticoid hormones on bovine neutrophils. This work provides one model to describe complex changes that occur in neutrophils as the cells respond to glucocorticoids, which might act to alter the cells' functional priorities and tip the delicate balance between health and disease during stress, including at parturition. A bovine immunobiology microarray and real time RT-PCR were used to study blood neutrophils collected during the natural surge of endogenous glucocorticoid (cortisol) in parturient dairy cows and bone marrow neutrophils collected from glucocorticoid (dexamethasone)-treated dairy steers. The gene expression signatures we observed led us to perform additional phenotyping of the neutrophils and correlation analyses, which together painted a picture suggesting that glucocorticoids have key roles in modulating neutrophil development, life span, and tissue defense functions during parturition and hormone therapy. Based on these observations, we postulate that glucocorticoids orchestrate adaptive changes in the entire neutrophil system that support increased cell numbers and longevity in blood and heightened remodeling activity in tissues, while at the same time decreasing some important antimicrobial defense activities of the cells. Thus, our functional genomics studies have enabled us to elucidate multiple consequences of neutrophil exposure to glucocorticoids, highlighting a probable role for this interaction in the induction of parturition and partly explaining why some parturient dairy cows may experience heightened incidence and severity of inflammatory diseases like mastitis.

Animals↗

PubMed2004

Contour grouping: closure effects are explained by good continuation and proximity.

Previous experimental studies have provided evidence that closed contours are easier to detect than open contours in random-element displays, and previous theoretical studies have shown that these effects might be explained by an active neural mechanism (e.g., a "reverberating neural circuit") sensitive to closure. To test this hypothesis, detection thresholds were measured in five experiments designed to control for the effects of uncertainty, eccentricity, and element density. In four of the experiments, we found that closed contours were no easier to detect than open contours, and in the remaining experiment the effects were consistent with the predictions of probability summation. Thus, we could find no evidence for an active neural mechanism that enhances detectability of closed contours more than open contours, although some form of closure mechanism may play a significant role in image interpretation.

Form Perception↗

PubMed2005

Neural latencies do not explain the auditory and audio-visual flash-lag effect.

A brief flash presented physically aligned with a moving stimulus is perceived to lag behind, a well studied phenomenon termed the Flash-Lag Effect (FLE). It has been recently shown that the FLE also occurs in audition, as well as cross-modally between vision and audition. The present study has two goals: to investigate the acoustic and cross-modal FLE using a random motion technique; and to investigate whether neural latencies may account for the FLE in general. The random motion technique revealed a strong cross-modal FLE for visual motion stimuli and auditory probes, but not for the other conditions. Visual and auditory latencies for stimulus appearance and for motion were measured with three techniques: integration, temporal alignment and reaction times. All three techniques showed that a brief static acoustic stimulus is perceived more rapidly than a brief static visual stimulus, while a sound source in motion is perceived more slowly than a comparable visual stimulus. While the results of these three techniques agreed closely with each other, they were exactly opposite that required to account for the FLE by neural latencies. We conclude that neural latencies do not, in general, explain the flash-lag effect. Rather, our data suggest that neural integration times are more important.

Acoustic Stimulation↗

PubMed2006

Can the theory of "whitening" explain the center-surround properties of retinal ganglion cell receptive fields?

To account for the spatial and temporal response properties of the retina, a number of studies have proposed that these properties serve to "whiten" the visual input. In particular, it has been argued that the sensitivity of retinal ganglion cells is matched to the spatial frequency spectrum of natural scenes, resulting in a flattened or "whitened" response spectrum across a range of frequencies. However, we argue that there are two distinct hypotheses regarding the flattening of the spectrum. The decorrelation hypothesis proposes that the magnitude of each ganglion cell tuning curve rises with spatial frequency, resulting in a flattened response spectrum for natural scene stimuli. With appropriate sampling, this scheme allows neighboring neurons to be uncorrelated with each other. The response equalization hypothesis proposes that the overall response magnitude of neurons increases with spatial frequency. The proposed goal of this model is to allow neurons with different receptive field sizes to produce the same average response to natural scenes. The response equalization hypothesis proposes an explanation for the relative gain of different ganglion cells and we show that this proposal fits well with published data. We suggest that both hypotheses are important in understanding the tuning and sensitivity of ganglion cells. However, using a simulation, both models are shown to be insufficient to explain the center-surround receptive field organization of ganglion cells. We discuss other factors, including representational sparseness, which could be related to the goals of ganglion cell spatial processing. We suggest three constraints needed to describe the basic linear properties of P-type ganglion cells: decorrelation, response equalization, and a minimal wiring or minimal size constraint.

Animals↗

PubMed2005

Does competition for phosphate supply explain the invasion pattern of Elodea species?

Two invasive aquatic plants, Elodea canadensis and Elodea nuttallii, occurred in north-eastern France. In this study, we examine the influence of phosphorus availability in soft water streams to explain the invasion pattern of exotic species (E. nuttallii and E. canadensis) compared to native plants (Callitriche platycarpa, Ranunculus peltatus). Total phosphorus was measured in these four aquatic macrophytes. Sediment total phosphorus and water-soluble reactive phosphorus were also analysed each season in 2001. Phosphorus content in the two invasive species and in R. peltatus was higher than in C. platycarpa. Elodea species are adapted to the seasonal phosphorus fluctuations as well as R. peltatus and exhibited high phosphorus storage ability. The high fluctuation availability of resources in space or/and time favoured the spread of the invasive plants and confirms the theory of invasibility of Davis et al. [2000. Fluctuating resources in plant communities: a general theory of invasibility. J. Ecol. 88, 528-534]. The eutrophication process increases the invasibility of E. nuttallii's, while inducing competition between E. nuttallii and native macrophyte species.

Ecosystem↗

PubMed2006

Formation of new genes explains lower intron density in mammalian Rhodopsin G protein-coupled receptors.

Mammalian G protein-coupled receptor (GPCR) genes are characterised by a large proportion of intronless genes or a lower density of introns when compared with GPCRs of invertebrates. It is unclear which mechanisms have influenced intron density in this protein family, which is one of the largest in the mammalian genomes. We used a combination of Hidden Markov Models (HMM) and BLAST searches to establish the comprehensive repertoire of Rhodopsin GPCRs from seven species and performed overall alignments and phylogenetic analysis using the maximum parsimony method for over 1400 receptors in 12 subgroups. We identified 14 different Ancestral Receptor Groups (ARGs) that have members in both vertebrate and invertebrate species. We found that there exists a remarkable difference in the intron density among ancestral and new Rhodopsin GPCRs. The intron density among ARGs members was more than 3.5-fold higher than that within non-ARG members and more than 2-fold higher when considering only the 7TM region. This suggests that the new GPCR genes have been predominantly formed intronless while the ancestral receptors likely accumulated introns during their evolution. Many of the intron positions found in mammalian ARG receptor sequences were found to be present in orthologue invertebrate receptors suggesting that these intron positions are ancient. This analysis also revealed that one intron position is much more frequent than any other position and it is common for a number of phylogenetically different Rhodopsin GPCR groups. This intron position lies within a functionally important, conserved, DRY motif which may form a proto-splice site that could contribute to positional intron insertion. Moreover, we have found that other receptor motifs, similar to DRY, also contain introns between the second and third nucleotide of the arginine codon which also forms a proto-splice site. Our analysis presents compelling evidence that there was not a major loss of introns in mammalian GPCRs and formation of new GPCRs among mammals explains why these have fewer introns compared to invertebrate GPCRs. We also discuss and speculate about the possible role of different RNA- and DNA-based mechanisms of intron insertion and loss.

Animals↗

PubMed2004

Current or lifetime smoking? Consequences for explaining educational inequalities in self-reported health.

BACKGROUND: Studies explaining educational differences in health often employ current smoking as a mediator. To what extent does lifetime smoking mediate the association between education and self-reported health better than current smoking? METHODS: Analysis of cross-sectional data from a representative general population sample of Dutch men and women (n = 1,561) with complete retrospective smoking histories. RESULTS: Educational differences in smoking over the life course are more pronounced than educational differences in current smoking, especially among men. The association between education and self-reported health is reduced when controlling for smoking for men. Among women, smoking is not such a mediator. The odds ratio for men with primary education to report less than good health is reduced from 2.94 (95% CI: 1.20-6.30) to 2.62 (95% CI: 1.13-6.05) when current smoking is taken into account and to 2.14 (95% CI: 0.90-5.04) when lifetime smoking is controlled for. This reduction in the difference between the highest and lowest educated is approximately 30% and statistically significant. For women, reductions are smaller and non-significant. CONCLUSIONS: Educational differences in smoking among men are underestimated if current instead of lifetime smoking is studied. Consequently, the contribution of smoking to bringing about social inequalities in health is underestimated if current smoking is measured.

Adult↗

PubMed2001

Explaining national road fatalities.

The purpose of this paper is to report on a model that can be used to explain the differences in road fatalities of individual countries. National infrastructure, transportation and socio-economic variables from international databases were considered as possible variables. The model was developed by means of stepwise regression analyses. It was found that the passenger car ownership is a better predictor of fatalities per 100000 passenger cars than vehicle ownership as a predictor of fatalities per 100000 vehicles. Many individual infrastructure and socio-economic variables have a significant effect on the fatality rate. The final model includes passenger car ownership, the Human Development Index (HDI), and the percentage of other vehicles as explanatory variables.

Accidents, Traffic↗