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At least 667 records · Page 37Linked to original sources
PubMed2005

LRP5 gene polymorphisms and idiopathic osteoporosis in men.

Mutations in the low-density lipoprotein receptor-related protein 5 gene (LRP5) have demonstrated the role of LRP5 in bone mass acquisition. LRP5 variants were recently reported to contribute to the population-based variance in vertebral bone mass and size in males. To investigate whether LRP5 variants are implicated in idiopathic male osteoporosis, we studied 78 men with low BMD (<2.5 T score or < -2 Z score) aged less than 70 years (mean +/- SD: 50 +/- 16 years) in whom secondary causes of osteoporosis had been excluded and 86 controls (51 +/- 10 years). Genotypes and haplotypes were based on LRP5 missense substitutions in exons 9 (c.2047G > A, p.V667M) and 18 (c.4037C > T, p.A1330V), and their association with osteoporosis evaluated after adjustment for multiple clinical and environmental variables using logistic regression. The presence of osteoporosis was significantly associated with LRP5 haplotypes (P = 0.0036) independent of age (P = 0.006), weight (P = 0.004), calcium intake (P = 0.002), alcohol (P = 0.005) and tobacco (P = 0.004) consumption. Accordingly, the odds ratio for osteoporosis was 3.78 (95% CI 1.27-11.26, P < 0.001) in male carriers of haplotype 3 (c.2047A-4037T, n = 20 cases and 12 controls) versus homozygous carriers of haplotype 1 (c.2047G-4037C, n = 42 cases and 61 controls). In conclusion, these data indicate beyond a significant role for environmental factors, an association between LRP5 variants and idiopathic osteoporosis in males, pointing to a role of LRP5 in this disease.

Adult↗
PubMed2004

Flux, pulse, and spin: dynamic additions to the personality lexicon.

Personality constructs were proposed to describe intraindividual variability in interpersonal behavior. Flux refers to variability about an individual's mean score on an interpersonal dimension and was examined for the 4 poles of the interpersonal circumplex. Pulse and spin refer to variability about an individual's mean extremity and mean angular coordinate on the interpersonal circumplex. These constructs were measured using event-contingent recording. Latent state-trait analyses indicated high stability of flux in submissive, agreeable, and quarrelsome behaviors and some stability in the flux of dominance. Further analyses indicated moderate to high stability in pulse and spin. Neuroticism predicted greater pulse, spin, and submissive behavior flux. Extraversion predicted greater flux in agreeable behavior. In contrast, Agreeableness predicted reduced spin and quarrelsome behavior flux. Social environmental variables predicted greater flux in dominant behavior. Flux, pulse, and spin provide reliable and distinctive additions to the vocabulary for describing individual differences.

Adult↗
PubMedDate not supplied

Environmental and policy factors associated with overweight among adults in Missouri.

PURPOSE: To measure the association between environmental and policy factors (i.e., community perceptions, community infrastructure, and worksite infrastructure) and being overweight. DESIGN: Cross-sectional data from the Missouri Cardiovascular Disease Survey, a one-time random-digit-dialed telephone interview of noninstitutionalized adults. SETTING: Missouri, 1999 to 2000. SUBJECTS: The response rate was 69.6%. A total of 2821 adults completed the interview. The sample was weighted to represent the population of Missouri: 52% female, 71% white, and 59% overweight. MEASURES: The survey comprised 92 closed-ended multiple-choice items. Overweight was defined as a body mass index greater than or equal to 25 kg/m2 on the basis of self-reported height and weight. RESULTS: After adjustment for demographic and behavioral factors, environmental variables associated with being overweight included negative (i.e., unsafe and unpleasant) community perceptions (adjusted odds ratio [OR] = 1.6; 95% confidence interval [CI] = 1.1, 2.3) and the absence of outdoor exercise facilities (OR = 1.2; CI = 1.0, 1.5). Worksite policy variables were not related to the outcome; however, negative community perceptions (OR = 2.8; CI = 1.5, 5.2) and the absence of sidewalks and shoulders (OR = 1.7; CI = 1.3, 2.4) were associated with overweight among employed persons. CONCLUSIONS: An ecological perspective, focusing on the physical and social environment, was adopted to address the subject of overweight and obesity. Results of this study show that negative perceptions of the physical environment and the absence of enabling infrastructure are modestly associated with overweight, in comparison with other known risk factors. Environmental and policy interventions that promote healthier lifestyles by encouraging physical activity and healthy eating may have an effect on reducing the prevalence of overweight and obesity.

Adolescent↗
PubMed2006

Completion of therapy by Medicare patients with stage III colon cancer.

BACKGROUND: Certain factors, such as race or age, are known to be associated with variation in initiation of adjuvant chemotherapy for stage III colon cancer, but little is known about what factors are associated with completion of adjuvant therapy. To determine whether predictors of initiation also predict completion, we analyzed Surveillance, Epidemiology, and End Results (SEER) program data linked to Medicare claims. We investigated mortality as a means to testing the validity of the completion measure that we created. METHODS: We studied 3193 stage III colon cancer patients whose diagnosis was recorded in 1992-1996 SEER program data linked to 1991-1998 Medicare claims and who initiated adjuvant chemotherapy after colon cancer resection. We defined a measure of adjuvant chemotherapy completion as one chemotherapy administration claim in a month. We tested the validity of the created measure and its relation to 3-year cancer mortality adjusted for demographic, clinical, and environmental variables. We explored the association of patient characteristics and treating physician characteristics with chemotherapy completion by use of multivariable logistic regression modeling. RESULTS: Of the 3193 patients, 2497 (78.2%) completed the course. Risk of cancer-related mortality was statistically significantly lower among those completing chemotherapy (relative risk = 0.79, 95% confidence interval = 0.69 to 0.89) than those with no adjuvant therapy. Patients who were female, widowed, increasingly elderly, rehospitalized, and living in certain regions were less likely to complete adjuvant chemotherapy than other patients. Race and other clinical, environmental, and physician characteristics were not associated with completion of therapy. CONCLUSIONS: Factors associated with incomplete adjuvant chemotherapy may represent physical frailty, treatment complications, and lack of social and psychological support. Interventions to mitigate these influences are a logical next step toward increasing chemotherapy completion rates.

Aged↗
PubMed2005

Spatial and temporal variability of necrophagous Diptera from urban to rural areas.

The spatio-temporal variability of necrophagous fly assemblages in a linear series of habitats from central London to the rural surroundings in the south-west was studied using bottle traps between June 2001 and September 2002. A total of 3,314 individuals in 20 dipteran families were identified from 127 sampling occasions. Calliphoridae accounted for 78.6% of all the dipteran specimens, with Calliphora vicina Robineau-Desvoidy, being the most abundant species (2,603 individuals, 46.9%). Using canonical correspondence analyses (CCA) on 72 fly taxa, six sampled sites and 36 environmental variables, three habitat types corresponding to three groups of flies were identified. These were an urban habitat characterized by C. vicina, Lucilia illustris (Meigen) and L. sericata (Meigen), a rural grassland habitat, characterized by L. caesar (Linnaeus) and a rural woodland habitat characterized by Calliphora vomitoria (Linnaeus), Phaonia subventa (Harris), Neuroctena anilis (Fallén) and Tephrochlamys flavipes (Zetterstedt). Intermediate species (L. ampullacea Villeneuve and P. pallida (Fabricius), located between the three habitats, were also found. Temporal abundance of the 10 most abundant species showed fluctuations between seasons, having low numbers of captured individuals during winter. Correspondence analysis showed clearly seasonal patterns at Box Hill site. The species-habitat associations suggest habitat differentiation between necrophagous guilds in this area and may be of ecological value.

Animals↗
PubMed1985

Ecological basis for regulating aquatic emissions from the power industry: the case with selenium.

Selenium can have severe ecological impacts on aquatic ecosystems even when waterborne concentrations are in the low microgram per liter (ppb) range. Episodes of environmental contamination have occurred that clearly illustrate the potential toxicity of this trace element to aquatic organisms. Wastes and effluents produced by the power industry are highly concentrated sources of selenium and constitute hazardous wastes when introduced into aquatic ecosystems. The continued use of a wet-basin system of coal-ash disposal at power plants is only feasible if several environmental variables are considered along with models of trace element cycling and accumulation, and pretreatment of effluents. Other power industry operations, such as coal gasification and liquifaction, must include provisions for treating effluents as an integral part of construction design. The ecological data base indicates that new, rigorous water quality criteria for selenium are needed; criteria presently proposed by EPA and others would not protect freshwater life if adopted as standards by regulatory agencies. This data base has been utilized by the State of North Carolina to develop sound, defensible environmental standards for selenium in surface waters. Ecological information can be used nationwide to establish reasonable and prudent regulations governing selenium-laden effluents from the power industry.

Animals↗
PubMed2005

Modelling the many-wrongs principle: the navigational advantages of aggregation in nomadic foragers.

We develop a simple individual-based model to gain an understanding of the drivers of aggregation behaviour in nomadic foragers. The model incorporates two key elements influencing nomadic foragers in variable environments: uncertainty regarding the location of food sources and variability in the spatio-temporal distribution of ephemeral food sources. A genetic algorithm is used to evolve parameters describing an individual's movement and aggregation strategy. We apply the aggregation model to a case study of the Bornean bearded pig (Sus barbatus). Bearded pigs are ideal for considering the foraging advantages of aggregation, because they are highly mobile and exhibit a variety of aggregation strategies, ranging from solitary and sedentary to mass aggregation and wide ranging migration. Our model demonstrates the "many-wrongs principle", and shows that environmental variability, uncertainty in the location of food sources, and local population density drive aggregation behaviour.

Animals↗
PubMed2001

Entropy generation method to quantify thermal comfort.

The present paper presents a thermodynamic approach to assess the quality of human-thermal environment interaction and quantify thermal comfort. The approach involves development of entropy generation term by applying second law of thermodynamics to the combined human-environment system. The entropy generation term combines both human thermal physiological responses and thermal environmental variables to provide an objective measure of thermal comfort. The original concepts and definitions form the basis for establishing the mathematical relationship between thermal comfort and entropy generation term. As a result of logic and deterministic approach, an Objective Thermal Comfort Index (OTCI) is defined and established as a function of entropy generation. In order to verify the entropy-based thermal comfort model, human thermal physiological responses due to changes in ambient conditions are simulated using a well established and validated human thermal model developed at the Institute of Environmental Research of Kansas State University (KSU). The finite element based KSU human thermal computer model is being utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal responses to different environmental conditions. The output from the simulation, which include human thermal responses and input data consisting of environmental conditions are fed into the thermal comfort model. Continuous monitoring of thermal comfort in comfortable and extreme environmental conditions is demonstrated. The Objective Thermal Comfort values obtained from the entropy-based model are validated against regression based Predicted Mean Vote (PMV) values. Using the corresponding air temperatures and vapor pressures that were used in the computer simulation in the regression equation generates the PMV values. The preliminary results indicate that the OTCI and PMV values correlate well under ideal conditions. However, an experimental study is needed in the future to fully establish the validity of the OTCI formula and the model. One of the practical applications of this index is that could it be integrated in thermal control systems to develop human-centered environmental control systems for potential use in aircraft, mass transit vehicles, intelligent building systems, and space vehicles.

Algorithms↗
PubMed2000

The diversity of beetle assemblages in different habitat types in Sabah, Malaysia.

The diversity of beetle assemblages in different habitat types (primary forest, logged forest, acacia plantation and oil palm plantation) in Sabah, Malaysia was investigated using three different methods based on habitat levels (Winkler sampling, flight-interception-trapping and mist-blowing). The overall diversity was extremely high, with 1711 species recorded from only 8028 individuals and 81 families (115 family and subfamily groups). Different degrees of environmental changes had varying effects on the beetle species richness and abundance, with oil palm plantation assemblage being most severely affected, followed by acacia plantation and then logged forest. A few species became numerically dominant in the oil palm plantation. In terms of beetle species composition, the acacia fauna showed much similarity with the logged forest fauna, and the oil palm fauna was very different from the rest. The effects of environmental variables (number of plant species, sapling and tree densities, amount of leaf litter, ground cover, canopy cover, soil pH and compaction) on the beetle assemblage were also investigated. Leaf litter correlated with species richness, abundance and composition of subterranean beetles. Plant species richness, tree and sapling densities correlated with species richness, abundance and composition of understorey beetles while ground cover correlated only with the species richness and abundance of these beetles. Canopy cover correlated only with arboreal beetles. In trophic structure, predators represented more than 40% of the species and individuals. Environmental changes affected the trophic structure with proportionally more herbivores (abundance) but fewer predators (species richness and abundance) in the oil palm plantation. Biodiversity, conservation and practical aspects of pest management were also highlighted in this study.

Animals↗
PubMedDate not supplied

Importance and difficulties of research on metal speciation in the aquatic ecosystem: an ecologist's viewpoint.

Post-war research on the role of heavy metals in the environment was stimulated by a new sensitivity towards nature, the increasing impact of human activities on the environment, continuous progress in analytical chemistry and the development of radioecology. Nowadays, very low concentrations of total metal can be quantified in the various compartments of the ecosystem (e.g. water, sediment, suspended particles, plants and animals), and the physical and chemical forms of the metal identified. A current difficulty is how to evaluate the role of the various metal forms in the natural ecosystem. The major issues to be tackled are: variations over time of metal species in relation to the influence of environmental variables; the fact that the availability of the metal varies with the plant and animal species; the ability of the organism to select the metals and their forms; the influence of suspended particles and chelating substances on metal uptake, detoxification strategies and synergic and antagonistic effects. The advantages and disadvantages of monitoring using bioaccumulator organisms are discussed.

Animals↗
PubMed2006

Litter and dead wood dynamics in ponderosa pine forests along a 160-year chronosequence.

Disturbances such as fire play a key role in controlling ecosystem structure. In fire-prone forests, organic detritus comprises a large pool of carbon and can control the frequency and intensity of fire. The ponderosa pine forests of the Colorado Front Range, USA, where fire has been suppressed for a century, provide an ideal system for studying the long-term dynamics of detrital pools. Our objectives were (1) to quantify the long-term temporal dynamics of detrital pools; and (2) to determine to what extent present stand structure, topography, and soils constrain these dynamics. We collected data on downed dead wood, litter, duff (partially decomposed litter on the forest floor), stand structure, topographic position, and soils for 31 sites along a 160-year chronosequence. We developed a compartment model and parameterized it to describe the temporal trends in the detrital pools. We then developed four sets of statistical models, quantifying the hypothesized relationship between pool size and (1) stand structure, (2) topography, (3) soils variables, and (4) time since fire. We contrasted how much support each hypothesis had in the data using Akaike's Information Criterion (AIC). Time since fire explained 39-80% of the variability in dead wood of different size classes. Pool size increased to a peak as material killed by the fire fell, then decomposed rapidly to a minimum (61-85 years after fire for the different pools). It then increased, presumably as new detritus was produced by the regenerating stand. Litter was most strongly related to canopy cover (r2 = 77%), suggesting that litter fall, rather than decomposition, controls its dynamics. The temporal dynamics of duff were the hardest to predict. Detrital pool sizes were more strongly related to time since fire than to environmental variables. Woody debris peak-to-minimum time was 46-67 years, overlapping the range of historical fire return intervals (1 to > 100 years). Fires may therefore have burned under a wide range of fuel conditions, supporting the hypothesis that this region's fire regime was mixed severity.

Biomass↗
PubMed2006

Relating geographical variation in pollination types to environmental and spatial factors using novel statistical methods.

The relative frequencies of functional traits of plant species show notable spatial variation, which is often related to environmental factors. Pollination type (insect-, wind- or self-pollination) is a critical trait for plant reproduction and provision of ecosystem services. Here, we mapped the distribution of pollination types across Germany by combining databases on plant distribution and plant pollination types. Applying a new method, we modelled the composition of pollination types using a set of 12 environmental variables as predictors within a Bayesian framework which allows for the analysis of compositional data in the presence of spatial autocorrelation. A clear biogeographical pattern in the distribution of pollination types was revealed which was adequately captured by our model. The most striking relationship was a relative increase in insect-pollination and a corresponding decrease of selfing with increasing altitude. Further important factors were wind speed, geology and land use. We present a powerful tool to analyse the distribution patterns of plant functional types such as pollination types and their relationship with environmental parameters in a spatially explicit framework.

Demography↗
PubMed1993

Changes in the cytotoxic T-cell repertoire of HIV-1-infected individuals: relationship to disease progression.

The repertoire of antigen-specific receptors expressed on T lymphocytes is shaped by fixed genetic and variable environmental selective pressures. Recent technological advances have enabled the analysis of T-cell receptor (TCR) expression in the context of selective pressures arising through normal immune system development and also through pathological features of disease. The pathological features of acquired immune deficiency syndrome (AIDS) are reflected by selective depletion of particular T lymphocyte subsets and expansion of others. An important question concerning the immunopathogenesis of AIDS is whether or not the perturbation of the CD4+ and CD8+ T-cell subsets following infection with human immunodeficiency virus (HIV) is selective based on TCR variable (V) region gene expression. To address this question, we have functionally analyzed TCR V gene expression on CD8+ cytotoxic T lymphocytes from HIV-1-infected individuals. This was done using monoclonal antibodies against individual TCR V regions to trigger redirected cytolysis in 51Cr release assays. The percent specific lysis induced by each antibody functionally measures the representation of the TCR V region gene product it is specific for. Relative to non-HIV-infected controls and asymptomatic HIV-infected individuals with only moderate CD4 lymphocyte depletion, HIV-infected individuals with low CD4 lymphocyte counts exhibited skewed patterns of TCR V region representation. Therefore, the perturbation within the CD8+ cytotoxic T lymphocyte repertoire in HIV infection appears to be selective based on TCR V region usage, increasingly so as disease progresses. The TCR V genes affected varied between different HIV-infected individuals and skewing detected in functional assays was not always apparent by flow cytometric analysis. These results suggest that HIV infection causes generalized effects on the T-cell repertoire, which are reflected in the relative TCR V gene representation of the CD8+ cytotoxic T lymphocyte population in peripheral blood.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Does rainfall explain variation in leaf morphology and physiology among populations of red ironbark (Eucalyptus sideroxylon subsp. tricarpa) grown in a common garden?

We investigated adaptation of leaf morphology and physiology of red ironbark (Eucalyptus sideroxylon Cunn. Ex. Wools subsp. tricarpa L.A.S. Johnson) in a common garden experiment. Fifteen populations, representing a rainfall range of 500 to 1055 mm per annum at the sites of seed collection, were grown at the same site. Because environmental variables other than rainfall did not vary significantly among populations, we were able to test if leaf morphology and physiology were related to seed-source rainfall. There were large differences among and within populations in all measured variables. Most univariate relationships with seed-source rainfall were not significant. Notable exceptions were the weak positive correlation of specific leaf area with seed-source rainfall-consistent with expectations-and the weak negative correlation of photosynthesis and stomatal conductance with seed-source rainfall-the opposite of what we predicted. In many cases, populations collected from sites of similar rainfall differed greatly in leaf morphology and physiology. Principal component analysis (PCA) reduced the 13 input variables to five principal components (PC) explaining 73.0% of the total variance in the original data. Some of the PC axes could be interpreted in terms of adaptation to drought (i.e., to seed-source rainfall), but relationships of accumulated variables (the PC axes) with seed-source rainfall were significant for only one PC axis. Hence, among red ironbark populations grown in a common garden, there was significant genetic variation in leaf morphology and physiology, but for most traits, this variation was unrelated to rainfall at the site of seed collection. This study adds to a growing body of common garden literature showing weak within-species relationships of leaf morphology and physiology with seed-source rainfall, in contrast to the consistently stronger relationships among species growing at different points along broad environmental gradients.

Eucalyptus↗
PubMed2006

Delimitation of lymphatic filariasis transmission risk areas: a geo-environmental approach.

BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis (GPELF) depends upon Mass Drug Administration (MDA) to interrupt transmission. Therefore, delimitation of transmission risk areas is an important step, and hence we attempted to define a geo-environmental risk model (GERM) for determining the areas of potential transmission of lymphatic filariasis. METHODS: A range of geo-environmental variables has been selected, and customized on GIS platform to develop GERM for identifying the areas of filariasis transmission in terms of "risk" and "non-risk". The model was validated through a 'ground truth study' following standard procedure using GIS tools for sampling and Immuno-chromotographic Test (ICT) for screening the individuals. RESULTS: A map for filariasis transmission was created and stratified into different spatial entities, "risk' and "non-risk", depending on Filariasis Transmission Risk Index (FTRI). The model estimation corroborated well with the ground (observed) data. CONCLUSION: The geo-environmental risk model developed on GIS platform is useful for spatial delimitation purpose on a macro scale.

Journal Article↗
PubMed2004

Biodiversity of Minnesota caddisflies (Insecta: Trichoptera): delineation and characterization of regions.

Despite the value of aquatic insects in aquatic ecosystem biomonitoring, few studies within North America have addressed relationships between aquatic insect assemblages and landscape-level environmental variables. In this study, over 300,000 adult caddisfly specimens representing 224 species were collected and analyzed from samples of 225 Minnesota aquatic habitats within 58 watersheds. Detrended Correspondence Analysis and a UPGMA dendrogram of caddisfly relative abundance data determined that five regions of caddisfly biodiversity exist within the state. Species richness and diversity were significantly highest in the Lake Superior and Northern regions, lowest in the Northwestern and Southern regions, and intermediate in the Southeastern region. Canonical Correspondence Analysis determined that caddisfly species composition was related to temperature, percentage of disturbed habitat, and stream gradient. Although a strong correlation between temperature and percentage of disturbed habitat made determination of the relative importance of those variables difficult, it is likely that anthropogenic disturbance has decreased caddisfly biodiversity in at least the Northwestern and Southern regions. Now that regions of biodiversity have been established, future changes to the fauna can be evaluated with greater precision and confidence. This study represents the most comprehensive faunal analysis of an aquatic insect order within the Western Hemisphere.

Animals↗
PubMed1994

Lead exposure of the child population in Greece.

Lead exposure of the child population was studied in three different areas in Greece: Kalamata which is a rural area of Southern Greece; Tavros, a district of Athens with a considerable industrial activity; and Lavrion, a small city near Athens where a lead-zinc mining and smelting industrial complex has existed for more than 90 years. The results were evaluated with respect to a number of individual, social and environmental variables (i.e. smelter, occupation of the father) especially those concerning the area of Lavrion which is the most heavily polluted area in Greece. The results of this study can be considered as an index for the extent of the lead pollution problem in the named areas of Greece.

Analysis of Variance↗
PubMed1988

Paralytic Shellfish Toxins in Protogonyaulax tamarensis and Protogonyaulax catenella in Axenic Culture.

Paralytic shellfish toxin concentrations were measured and individual toxin profiles were monitored in axenic batch cultures of Protogonyaulax tamarensis and Protogonyaulax catenella. High pressure liquid chromatographic methods were used that allowed the separation of all 12 known paralytic shellfish poisons, including toxins C1, C2, and C3, from a single sample. In isolates of both Protogonyaulax species, total toxin levels were relatively low after inoculation, increased rapidly in early to mid-exponential growth to a value 100 to 300% of that at the initial time point, then decreased by 86 to 95% as the culture aged. Although the concentrations of individual toxins per cell followed the same general pattern as that seen for total moles of toxin per cell, variability in toxin profile with culture age was observed. In P. tamarensis, the mole percent of neosaxitoxin increased substantially from 8 to 44% as total toxin levels per cell decreased. A concomitant decrease in the mole percent of saxitoxin with culture age was noted. Although not as precipitous, changes in the mole percent of specific toxins from P. catenella were also observed. The mole percent of gonyautoxins I and IV increased, while that of gonyautoxins II and III decreased. These data suggest that the toxin profile in isolates of Protogonyaulax can change, sometimes significantly, with changing environmental variables.

Journal Article↗