998 resultados para Milcz, Johannes.
Resumo:
Homeostasis in the intact organism is achieved implicitly by repeated incremental feedback (inhibitory) and feedforward (stimulatory) adjustments enforced via intermittent signal exchange. In separated systems, neurohormone signals act deterministically on target cells via quantifiable effector-response functions. On the other hand, in vivo interglandular signaling dynamics have not been estimable to date. Indeed, experimentally isolating components of an interactive network definitionally disrupts time-sensitive linkages. We implement and validate analytical reconstruction of endogenous effector-response properties via a composite model comprising (i) a deterministic basic feedback and feedforward ensemble structure; (ii) judicious statistical allowance for possible stochastic variability in individual biologically interpretable dose–response properties; and (iii) the sole data requirement of serially observed concentrations of a paired signal (input) and response (output). Application of this analytical strategy to a prototypical neuroendocrine axis in the conscious uninjected horse, sheep, and human (i) illustrates probabilistic estimation of endogenous effector dose–response properties; and (ii) unmasks statistically vivid (2- to 5-fold) random fluctuations in inferred target-gland responsivity within any given pulse train. In conclusion, balanced mathematical formalism allows one to (i) reconstruct deterministic properties of interglandular signaling in the intact mammal and (ii) quantify apparent signal-response variability over short time scales in vivo. The present proof-of-principle experiments introduce a previously undescribed means to estimate time-evolving signal-response relationships without isotope infusion or pathway disruption.
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Governments use fear to promote political objectives. Through the exaggeration of external threats, fear as conceptualised in the writings of Hobbes, Barry Buzan, David Campbell and others, became a major factor in shaping Australia's post-war foreign and defence policies which were also intended to serve the government's domestic political agenda.
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Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths). With >250 bone fragments/m2 and comprising 50% of all known extinct and extant vertebrate species (ns = 44) of Mauritius, MAS may constitute the first Holocene vertebrate bone Concentration-Lagerstätte identified on an oceanic volcanic island. Fossil remains are dominated by extinct giant tortoises Cylindraspis spp. (63%), passerines (10%), small bats (7.8%) and dodo Raphus cucullatus (7.1%). Twelve radiocarbon ages [four of them duplicates] from bones and other material suggest that accumulation of fossils took place within several centuries. An exceptional combination of abiotic conditions led to preservation of bones, bone collagen, plant tissue and microfossils. Although bone collagen is well preserved, DNA from dodo and other Mauritian vertebrates has proved difficult. Our analysis suggests that from ca 4000 years ago (4 ka), rising sea levels created a freshwater lake at MAS, generating an oasis in an otherwise dry environment which attracted a diverse vertebrate fauna. Subsequent aridification in the south-west Indian Ocean region may have increased carcass accumulation during droughts, contributing to the exceptionally high fossil concentration. The abundance of floral and faunal remains in this Lagerstätte offers a unique opportunity to reconstruct a pre-human ecosystem on an oceanic island, providing a key foundation for assessing the vulnerability of island ecosystems to human impact.
Resumo:
Objective. To explore the association between home environmental variables and television (TV) time, and the mediating pathways underlying this association.
Methods. The current study used data from the longitudinal ENDORSE study. Self-reported data was available for 1 265 adolescents (mean age of 12–15 years at baseline) on home environment (availability of a TV in the bedroom, perceived parental modelling, family rules), potential mediators (intention, attitude, perceived behavioural control, subjective norm towards TV viewing) and TV viewing time. Mediation analyses were conducted using General Estimating Equations and mediation effects were calculated as the product-of-coefficients.
Results. Significant overall positive associations were found for the presence of a TV in the bedroom and parental modelling with self-reported TV viewing. Controlling family rules showed an inverse association with reported TV time. Similarly, parental modelling and a TV in the bedroom were significantly positively associated with the Theory of Planned Behaviour variables and habit strength, while family rules showed an inverse association with these potential mediators. In turn, most potential mediators were positively associated with TV viewing. Intention, attitude and habit strength were the strongest mediators in all three associations explaining more than 55% of the overall association. Habit strength alone explained 38.2%–58.0% of the overall associations.
Conclusions. Home and family environmental predictors of TV time among adolescents may be strongly mediated by habit strength and other personal factors. Future intervention studies should explore if changes in home and family environments indeed lead to reductions in TV time through these mediators.
Resumo:
This longitudinal study aimed to identify individual and environmental predictors of adolescents’ sports participation and to examine whether availability of sports facilities moderated the intention–behaviour relation. Data were obtained from the ENvironmental Determinants of Obesity in Rotterdam SchoolchildrEn study (2005/2006 to 2007/2008). A total of 247 adolescents (48% boys, mean age at follow-up 15 years) completed the surveys at baseline and follow-up. At baseline, adolescents completed a survey that assessed engagement in sports participation, attitude, subjective norm, perceived behavioural control and intention towards sports participation. Availability of sports facilities (availability) was assessed using a geographic information system. At follow-up, sports participation was again examined. Multiple logistic regression analyses were conducted to test associations between availability of sports facilities, theory of planned behaviour variables and the interaction of intention by availability of sports facilities, with sports participation at follow-up. Simple slopes analysis was conducted to decompose the interaction effect. A significant availability × intention interaction effect [odds ratio: 1.10; 95% confidence interval: 1.00–1.20] was found. Simple slopes analysis showed that intention was more strongly associated with sports participation when sports facilities were more readily available. The results of this study indicate that the intention–sports participation association appears to be stronger when more facilities are available.
Resumo:
Objective. To examine associations between social ecological factors and Dutch adolescents’ TV viewing. Design. Cross-sectional examination of predictors of adolescents’ TV viewing.
Participants. A total of 338 adolescents, aged 14 years (55% boys).
Measurements. Adolescents self-reported their age, ethnicity and TV viewing (dichotomized at two hours/day) and responded to items from all three social ecological domains; individual (cognitions based on the Theory of Planned Behaviour and TV viewing habit strength, and other behaviours, such as computer use), social (parental rules about TV viewing and parental TV viewing behavior) and physical environmental factors (TV in bedroom, physical activity equipment available). Parents reported demographic factors (e.g., ethnicity, education level), and their own TV viewing (mins/day); adolescents’ weight status (not overweight vs. overweight/obese) was calculated from objective measures of height and weight. Logistic regression analyses examined associations between socio-ecological factors and adolescents’ TV viewing, and whether associations were moderated by adolescents’ sex, parents’ education and ethnicity.
Results. Compared with others, overweight/obese adolescents (odds ratio (OR)=3.0; p≤0.001), those with high computer use (OR=2.3; p≤0.0001), with high TV viewing habit strength (OR=1.3; p≤0.0001), and those whose parents had high levels of TV viewing (OR=2.4; p≤0.01) were more likely to exceed two hours of TV viewing per day. The association with habit strength was moderated by gender, and the association with parents’ TV viewing was moderated by parents’ education and ethnicity.
Conclusions. Interventions should target parents’ TV viewing behaviors and aim to amend habitual, ‘mindless’ TV viewing among adolescents.
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Objective The Dutch Obesity Intervention in Teenagers (DOiT) is a school-based randomised controlled trial that was effective in decreasing the consumption of sugar-sweetened beverages among adolescents. The present study examined, using mediation analysis, whether this decrease in consumption of sugar-sweetened beverages could be explained by an increase in the consumption of water or diet drinks.
Design Participants completed a questionnaire about their beverage consumption at baseline and at 8 months (immediately post-intervention), 12- and 20-month follow-ups. A series of multi-level linear regression analyses were performed to examine water and diet drink consumption as potential mediators of the intervention effect on the consumption of sugar-sweetened beverages.
Setting Eighteen Dutch secondary schools.
Subjects A total of 747 adolescents (mean age: 12·7 years).
Results In addition to the DoiT intervention effect of a reduction in the consumption of sugar-sweetened beverages at 8 months (−284 ml/d; 95 % CI −420, −148) and 12 months (−260 ml/d; 95 % CI −360, −160), there was also a significant reduction in diet drinks at 8 months (−52 ml/d; 95 % CI −89, −16). There was no significant difference in water consumption at any follow-up. The decrease in sugar-sweetened beverage consumption could not be explained by an increase in water or diet drink consumption at any time point.
Conclusions Interventions aimed at reducing sugar-sweetened beverage consumption may be effective without changing consumption of other beverages. Reducing sugar-sweetened beverages was, however, a main message of the DOiT intervention. It is possible that a concomitant promotion of water may have resulted in a greater increase in water intake and replacement of sugar-sweetened beverages with water.
Resumo:
Background
There is an urgent need for more carefully developed public health measures in order to curb the obesity epidemic among youth. The overall aim of the "EuropeaN Energy balance Research to prevent excessive weight Gain among Youth" (ENERGY)-project is the development and formative evaluation of a theory-informed and evidence-based multi-component school-based and family-involved intervention program ready to be implemented and evaluated for effectiveness across Europe. This program aims at promoting the adoption or continuation of health behaviors that contribute to a healthy energy balance among school-aged children. Earlier studies have indicated that school and family environments are key determinants of energy-balance behaviors in schoolchildren. Schools are an important setting for health promotion in this age group, but school-based interventions mostly fail to target and involve the family environment.
Methods
Led by a multidisciplinary team of researchers from eleven European countries and supported by a team of Australian experts, the ENERGY-project is informed by the Environmental Research Framework for Weight gain Prevention, and comprises a comprehensive epidemiological analysis including 1) systematic reviews of the literature, 2) secondary analyses of existing data, 3) focus group research, and 4) a cross European school-based survey.
Results and discussion
The theoretical framework and the epidemiological analysis will subsequently inform stepwise intervention development targeting the most relevant energy balance-related behaviors and their personal, family-environmental and school-environmental determinants applying the Intervention Mapping protocol. The intervention scheme will undergo formative and pilot evaluation in five countries. The results of ENERGY will be disseminated among key stakeholders including researchers, policy makers and the general population.
Conclusions
The ENERGY-project is an international, multidisciplinary effort to develop and test an evidence-based and theory-informed intervention program for obesity prevention among school-aged children.
Resumo:
Although recognised clinically for some time as an important condition that increases risk of ill-health in affected individuals, it is only recently that obesity had been recognised as a population-wide problem that requires preventive action. Obesity is a major contributor to diseases and disability, the associated health costs are enormous and obesity has already reached epidemic proportions in many countries, and incidence is continuing to increase in children and adults. Disturbingly the epidemic is not confined to developed countries, with many developing countries and those in transition affected. While recognised as a major population health problem, our understanding of the causes of the epidemic is poor, there has been relatively little population-based research that has focused on the prevention of unhealthy weight gain, and as a consequence knowledge regarding how and where best to intervene is limited.Revised and updated and now part of the From Aetiology to Public Health series, Obesity Epidemiology provides a scholarly text that assists those concerned with understanding prevalence and trends in obesity; its health, social and economic consequences, the underlying causes of the obesity epidemic, the existing evidence regarding strategies to prevent obesity, and the potential of public health initiatives to impact on the population prevalence of obesity. This edition not only provides a thorough update of the material presented in the previous edition (entitled Obesity Prevention and Public Health), but also includes twelve new chapters that cover the epidemiology of obesity in children and adults, and the potential of public health approaches to its prevention. This book will be of interest to all those working in public health and epidemiology; health policy makers, and clinicians and health practitioners working in the related fields of nutrition, exercise and diabetes.About the seriesBy looking at public health issues from a unique condition-based approach, the innovative From Aetiology to Public Health series examines top public health issues from aetiology through to public health and prevention
