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Environmental Background (environmental + background)
Selected AbstractsEarly cannabis use and DSM-IV nicotine dependence: a twin studyADDICTION, Issue 11 2008Arpana Agrawal ABSTRACT Background Evidence suggests that cannabis users are at increased risk for cigarette smoking,if so, this may potentially be the single most alarming public health challenge posed by cannabis use. We examine whether cannabis use prior to age 17 years is associated with an increased likelihood of DSM-IV nicotine dependence and the extent to which genetic and environmental factors contribute to this association. Methods A population-based cohort of 24,36-year-old Australian male and female twins (n = 6257, 286 and 229 discordant pairs) was used. The co-twin,control method, with twin pairs discordant for early cannabis use, was used to examine whether, after controlling for genetic and familial environmental background, there was evidence for an additional influence of early cannabis use on DSM-IV nicotine dependence. Bivariate genetic models were fitted to the full data set to quantify the genetic correlation between early cannabis use and nicotine dependence. Results The early cannabis-using twin was about twice as likely to report nicotine dependence, when compared to their co-twin who had experimented with cigarettes but had never used cannabis. Even when analyses were restricted to cannabis users, earlier age cannabis use onset conferred greater risk (1.7) for nicotine dependence than did later onset. This association was governed largely by common genetic liability to early cannabis use and nicotine dependence, as demonstrated by genetic correlations of 0.41,0.52. Conclusions Early-onset cannabis users are at increased risk for nicotine dependence, but this risk is attributable largely to common genetic vulnerability. There is no evidence for a causal relationship between cannabis use and nicotine dependence. [source] Behavioral phenotyping enhanced , beyond (environmental) standardizationGENES, BRAIN AND BEHAVIOR, Issue 1 2002H. Würbel It is basic biology that the phenotype of an animal is the product of a complex and dynamic interplay between nature (genotype) and nurture (environment). It is far less clear, however, how this might translate into experimental design and the interpretation of animal experiments. Animal experiments are a compromise between modelling real world phenomena with maximal validity (complexity) and designing practicable research projects (abstraction). Textbooks on laboratory animal science generally favour abstraction over complexity. Depending on the area of research, however, abstraction can seriously compromise information gain, with respect to the real world phenomena an experiment is designed to model. Behavioral phenotyping of mouse mutants often deals with particularly complex manifestations of life, such as learning, memory or anxiety, that are strongly modulated by environmental factors. A growing body of evidence indicates that current approaches to behavioral phenotyping might often produce results that are idiosyncratic to the study in which they were obtained, because the interactive nature of genotype-environment relationships underlying behavioral phenotypes was not taken into account. This paper argues that systematic variation of genetic and environmental backgrounds, instead of excessive standardization, is needed to control the robustness of the results and to detect biologically relevant interactions between the mutation and the genetic and environmental background of the animals. [source] An Analysis of the Barriers Hindering Small Business Export DevelopmentJOURNAL OF SMALL BUSINESS MANAGEMENT, Issue 3 2004Leonidas C. Leonidou Notwithstanding the benefits derived from exporting in an increasingly globalized marketplace, for many smaller-sized manufacturers the internationalization path is beset by numerous obstacles. This article offers a comprehensive analysis of 39 export barriers extracted from a systematic review of 32 empirical studies conducted on the subject. These have been classified into internal (incorporating informational, functional, and marketing) and external (comprising procedural, governmental, task, and environmental) barriers. The impact of export barriers is shown to be situation-specific, largely depending on the idiosyncratic managerial, organizational, and environmental background of the firm. However, certain barriers, such as those relating to information inefficiencies, price competitiveness, foreign customer habits, and politicoeconomic hurdles, seem to have a systematically strong obstructing effect on export behavior. Several conclusions and implications for small business managers, public policymakers, business educators, and exporting researchers are derived. [source] Karst rocky desertification in southwestern China: geomorphology, landuse, impact and rehabilitationLAND DEGRADATION AND DEVELOPMENT, Issue 2 2004S.-J. Wang Abstract Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks, drastic decrease in soil productivity, and the appearance of a desert-like landscape. It is caused by irrational, intensive land use on a fragile karst geo-ecological environment. The process is expanding rapidly, and it is daily reducing the living space of residents and is the root of disasters and poverty in the karst areas of southwestern China. The tectonic, geomorphic and environmental background to karst rocky desertification is analysed. Population pressure and the intensive land use that have led to this serious land degradation are described. Although the problem concerns the Chinese Government and some profitable experience in the partial restoration or reconstruction of the ecological environment has been gained, effective remedial action has not been achieved on a large scale. Copyright © 2004 John Wiley & Sons, Ltd. [source] Restless legs syndrome: Epidemiological and clinicogenetic study in a South Tyrolean population isolateMOVEMENT DISORDERS, Issue 8 2006Florian D. Vogl MSc Abstract Genetic contributions to restless legs syndrome (RLS) have been consistently recognized from population and family studies. To determine the clinical and genetic features of RLS in a population isolate and explore linkage to three previously described susceptibility loci on chromosomes 12q, 14q, and 9p, respectively, an isolated population in the South Tyrolean Alps was identified and 530 adults participated in the study. Using a two-step strategy, 47 patients with idiopathic RLS were ascertained. The prevalence in the population was 8.9%. Twenty-eight patients (59.6%) had at least one affected first-degree relative and were classified as hereditary cases. In a single extended pedigree, linkage to known RLS loci was investigated specifying autosomal dominant and recessive models; parametric and nonparametric multipoint linkage scores were computed. None of the calculated linkage scores was suggestive of linkage between RLS and any of the three investigated loci. This study was conducted in a population isolate providing for a homogeneous genetic and environmental background. The absence of a suggestive linkage signal at the three known RLS susceptibility loci is indicative of further locus heterogeneity of this frequent disorder and encourages further studies to unveil the genetic causes of RLS. © 2006 Movement Disorder Society [source] Presence and distribution of PAHs, PCBs and DDE in feed and sediments under salmon aquaculture cages in the Bay of Fundy, New Brunswick, CanadaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2005J. Hellou Abstract 1.Wastes from feed and faeces can result in the deposition of contaminants in sediments around aquaculture sites. Five types of feed pellet, a commercial fish oil and 76 sediment samples collected under and up to 100 m away from salmon aquaculture cages in the south-western Bay of Fundy between 1998 and 2000 were analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and chlorinated pesticides. 2.Five alkylated naphthalenes (aNAs) were consistently detected in fish oil (116,180 ng g,1, per aNA), in pellets (25,51 ng g,1, dry weight, per aNA), and sediments (<1,45 ng g,1, dry weight, per aNA). Other PAHs were detected at variable levels in feed or in sediments. 3.IUPAC congener 153 (a PCB) and p,p,-dichlorodiphenyldichloroethylene (p,p,-DDE) were detected more frequently than other chlorinated targets in oil (108 ng g,1 and 176 ng g,1 respectively), feed (<1,14 ng g,1 and 1.7,28.2 ng g,1 respectively) and sediments (<0.08,3 ng g,1 and <0.5,7 ng g,1 respectively). 4.Trends were observed during the first year of sediment sampling (1998), with higher organic carbon, PCBs and p,p,-DDE levels below the cages than 50 m away. The PAHs other than aNA showed an opposite trend with distance. In 1999, levels of p,p,-DDE and PCBs were somewhat reduced under the cages, but were detected up to 100 m away from the cages. 5.Levels of aNA tended to be higher at some sites in 1999 relative to 1998, reflecting variability in feed and/or differential transport or degradation of contaminants relative to the environmental background. When detected, mean levels of PCBs and DDE were 2,10 times lower in 2000 than in 1999, and PAHs were 30,40% lower in 2000 than in 1999. 6.Interpretation of the results is done cautiously, since the exact locations of the sites sampled is only known to an intermediate facilitating the work between farmers and scientists. Levels of contaminants are compared with international results, interpreted relative to potential toxicity, uptake from feed, from deposited sediments, and in the framework of an aquaculture decision-support system published recently. Copyright © 2005 John Wiley & Sons, Ltd. [source] Review article: The impact of obesity on reproduction in women with polycystic ovary syndromeBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 10 2006R Pasquali The polycystic ovary syndrome (PCOS) is one of the most common causes of infertility due to anovulation in women. The clinical features of PCOS are heterogeneous and may change throughout the lifespan, starting from adolescence to postmenopausal age. This is largely dependent on the influence of obesity and metabolic alterations, including an insulin-resistant state and the metabolic syndrome, which consistently affect most women with PCOS. Obesity does in fact have profound effects on both the pathophysiology and the clinical manifestation of PCOS, by different mechanisms leading to androgen excess and increased free androgen availability and to alterations of granulosa cell function and follicle development. Notably, simple obesity per se represents a functional hyperandrogenic state. These mechanisms involve early hormonal and metabolic factors during intrauterine life, leptin, insulin and the insulin growth factor system and, potentially, the endocannabinoid system. Compared with normal weight women with PCOS, those with obesity are characterised by a worsened hyperandrogenic and metabolic state, poorer menses and ovulatory performance and, ultimately, poorer pregnancy rates. The importance of obesity in the pathogenesis of PCOS is emphasised by the efficacy of lifestyle intervention and weight loss, not only on metabolic alterations but also on hyperandrogenism, ovulation and fertility. The increasing prevalence of obesity among adolescent and young women with PCOS may partly depend on the increasing worldwide epidemic of obesity, although this hypothesis should be supported by long-term prospective epidemiological trials. This may have great relevance in preventive medicine and offer the opportunity to expand our still limited knowledge of the genetic and environmental background favouring the development of the PCOS. [source] Temporal Distribution of Diagnostic Biofabrics in the Lower and Middle Ordovician in North China: Clues to the Geobiology of the Great Ordovician Biodiversification EventACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009Jianbo LIU Abstract: The temporal distribution of the diagnostic biofabrics in the Lower and Middle Ordovician in North China distinctly illustrates that the sedimentary systems on the paleoplate have been changed markedly as consequences of the Great Ordovician Biodiversification Event (GOBE). The pre-GOBE sedimentary systems deposited in Tremadoc display widespread microbialite and flat-pebble conglomerates, and a less extent of bioturbation. Through the transitional period of early Floian, the sedimentary systems in the rest of the Early and Mid- Ordovician change to GOBE type and are characterized by intensive bioturbation and vanishing flat-pebble conglomerates and subtidal microbial sediments. The irreversible changes in sedimentary systems in North China are linked to the GOBE, which conduced the increase in infaunal tiering, the expansion of infaunal ecospace, and the appearance of new burrowers related to the development of the Paleozoic Evolutionary Fauna during the Ordovician biodiversification. Thus, changes in sedimentary systems during the pivotal period of the GOBE were consequences of a steep diversification of benthic faunas rather than the GOBE's environmental background. [source] Behavioral phenotyping enhanced , beyond (environmental) standardizationGENES, BRAIN AND BEHAVIOR, Issue 1 2002H. Würbel It is basic biology that the phenotype of an animal is the product of a complex and dynamic interplay between nature (genotype) and nurture (environment). It is far less clear, however, how this might translate into experimental design and the interpretation of animal experiments. Animal experiments are a compromise between modelling real world phenomena with maximal validity (complexity) and designing practicable research projects (abstraction). Textbooks on laboratory animal science generally favour abstraction over complexity. Depending on the area of research, however, abstraction can seriously compromise information gain, with respect to the real world phenomena an experiment is designed to model. Behavioral phenotyping of mouse mutants often deals with particularly complex manifestations of life, such as learning, memory or anxiety, that are strongly modulated by environmental factors. A growing body of evidence indicates that current approaches to behavioral phenotyping might often produce results that are idiosyncratic to the study in which they were obtained, because the interactive nature of genotype-environment relationships underlying behavioral phenotypes was not taken into account. This paper argues that systematic variation of genetic and environmental backgrounds, instead of excessive standardization, is needed to control the robustness of the results and to detect biologically relevant interactions between the mutation and the genetic and environmental background of the animals. [source] Together we are heard: Effectiveness of daily ,language' groups in a community preschoolNURSING & HEALTH SCIENCES, Issue 2 2004Telêri Hodge BSc Abstract Strong oral language skills are a prerequisite for successful literacy and there is a strong interdependence between oral language acquisition and emergent literacy development. Ramifications of this are that children with language impairments are at great risk for difficulties in learning to read and write, with problems often persisting throughout the school years into adulthood. The Together we are heard program involved improving each child's oral language skills through group sessions facilitated by a speech pathologist on a daily basis at preschool. The aim of the present research was to determine the effectiveness of the program to identify the best way to assist children to develop appropriate language skills. The study showed that the children improved significantly in all four levels of the Preschool Language Assessment Inventory (PLAI). Importantly, the program was effective for both genders and there was no difference in the success of Indigenous children when compared to their European counterparts. There is a strong recommendation for further research and to expand such programs, particularly in areas that target children from impoverished and deprived environmental backgrounds. [source] Gene function beyond the single trait: natural variation, gene effects, and evolutionary ecology in Arabidopsis thalianaPLANT CELL & ENVIRONMENT, Issue 1 2005S. J. TONSOR ABSTRACT The purpose of plant functional genomics is to describe the patterns of gene expression and internal plant function underlying the ecological functions that sustain plant growth and reproduction. Plants function as integrated systems in which metabolic and developmental pathways draw on common resource pools and respond to a relatively small number of signal/response systems. Plants are also integrated with their environment, exchanging energy and matter with their surroundings and are consequently sensitive to changes in energy and resource fluxes. These two levels of integration complicate the description of gene function. Internal integration results in single genes often affecting multiple characteristics (pleiotropy) and interacting with multiple other genes (epistasis). Integration with the external environment leads to gene expression and the genes' phenotypic effects varying across environmental backgrounds (gene,environment interaction). An accurate description of the function of all genes requires an augmentation, already underway, of the study of isolated developmental and metabolic pathways to a more integrated approach involving the study of genetic effects across scales of variation usually regarded as the purview of ecological and evolutionary research. Since the evolution of gene function also depends on this complex of gene effects, progress in evolutionary genetics will also require understanding the nature of gene interactions and pleiotropy and the constraints and patterns they impose on adaptive evolution. Studying gene function in the context of the integrated organism is a major challenge, best met by developing co-ordinated research efforts in model systems. This review highlights natural variation in A. thaliana as a system for understanding integrated gene function in an ecological and evolutionary context. The current state of this research integration in A. thaliana is described by summarizing relevant approaches, current knowledge, and some potentially fruitful future studies. By introducing some of the fundamental questions of ecological and evolutionary research, experimental approaches and systems that can reveal new facets of gene function and gene effect are also described. A glossary is included in the Appendix. [source] | ||||||||||||||||