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PubMed2004

Expressive and receptive language functioning in preschool children with prenatal cocaine exposure.

OBJECTIVE: To estimate the relationship between severity of prenatal cocaine exposure and expressive and receptive language skills in full-term, African American children at age 3 years. METHODS: Language was assessed at age 3 using the Clinical Evaluation of Language Fundamentals-Preschool (CELF-P). The sample included 424 children (226 cocaine exposed, 198 non-cocaine exposed) who received preschool language assessments at age 3, drawn from a cohort of 476 children enrolled prospectively at birth. RESULTS: Structural equation modeling was used to regress expressive and receptive language as intercorrelated response variables on level of prenatal cocaine exposure, measured by a latent construct including maternal self-report of cocaine use and maternal/infant urine toxicology assays and infant meconium. Results indicated a.168 SD decrease in expressive language functioning for every unit increase in exposure level (95% CI = -.320, -.015; p =.031) after consideration for fetal growth and gestational age as correlated response variables. Receptive language was more modestly related to prenatal cocaine exposure and was not statistically significant. Results for expressive language remained stable with inclusion of the McCarthy general cognitive index as a response variable (expressive language beta = -.173, 95% CI = -.330, -.016; p =.031), and with adjustment for maternal age and prenatal exposures to alcohol, tobacco, and marijuana (expressive language beta = -.175, 95% CI = -.347, -.003; p =.046). Additional child and caregiver environmental variables assessed at age 3 were also evaluated in varying statistical models with similar results. CONCLUSION: The evidence from this study supports a gradient relationship between increased level of prenatal cocaine exposure and decreased expressive language functioning in preschool-aged cocaine-exposed children.

Child↗
PubMed1979

The physiological effects of restrictive environmental conditions on Dictyostelium discoideum spore germination.

Spores may be reversibly activated by the application of heat, dimethyl sulfoxide, urea, or ethylene glucol. Severe changes in four environmental variables (high osmotic pressure, low oxygen tension, low or high pH, and low or high temperature) interfere with the germination process. Spores at the end of the postactivation lag phase of germination were usually deactivated if exposed to severe environmental conditions and thus did not swell; spores in the swelling and oxygen uptake which began during spore activation was primarily attributable to a cyanide-sensitive pathway and secondarily to a salicylhydroxamic acid (SHAM) sensitive pathway. Inhibition of the SHAM-sensitive pathway did not cause spore deactivation while the addition of cyanide resulted in rapid spore deactivation. Treatment of activated spores with azide or environmental shifts also resulted in inhibition of oxygen uptake and spore deactivation. Deactivating spores did not demonstrate the amino acid incorporation, uridine incorporation, and expression of trehalase activity which is found in the later stages of germinating control spores. Protein synthesis inhibitors did not cause spore deactivation or a decrease in oxygen uptake but they inhibited amino acid incorporation and the expression trehalase activity in swollen spores. It is concluded that control of respiratory activity is involved in regulation of reversible activation.

Azides↗
PubMed2006

Environmental and individual predictors of error in field estimates of blood alcohol concentration: a multilevel analysis.

OBJECTIVE: Using self-report survey data and measures of breath alcohol concentration (BrAC), this study examined the validity of an estimate of blood alcohol concentration (eBAC). Differences between eBAC and BrAC were modeled to identify sources of error related to survey-derived eBAC. Further, using hierarchical multilevel analyses, environmental event characteristics were examined as sources of eBAC error. METHOD: College students were interviewed and provided breath samples at randomly selected parties on Friday and Saturday nights. Interviews included items assessing the total number of drinks consumed, duration of drinking event, gender, and weight, which allowed for the calculation of eBAC. RESULTS: Overall, eBACs were inaccurate. Total number of drinks consumed was associated with underestimates of eBAC, whereas time drinking was associated with overestimates of eBAC. Environmental variables, including party size, rowdy behavior, having food present, and observing many intoxicated partygoers, were also associated with eBAC errors. CONCLUSIONS: Current self-report survey methodology to calculate eBAC may be insufficient to estimate BAC with any accuracy. Environmental factors associated with the last drinking event for which BAC is being estimated should be considered when calculating eBAC.

Adolescent↗
PubMed2002

Improving ecological performance of electrical consumer products: the role of design-based measures and user variables.

This research is concerned with the ecological performance of electrical consumer products. It examines the influence of design-based measures on various ecological performance parameters and the relationship of user variables and performance. In the experimental scenario, 40 users were asked to clean a room with a vacuum cleaner under different conditions. In a multi-factorial design, the following independent variables were employed: on-product information, enhanced display-control labelling and proximity of controls. Measures of user variables (environmental concern, knowledge, habits) of ecological behaviour were also taken. The results showed that enhanced display-control labelling improved ecological performance but only when the label was placed close to the user. On-product information only resulted in behavioural change when it was in close spatial proximity to the control device. A positive effect on ecological performance was also observed when controls were in a proximal rather than distal position. Among user variables, habits were found to have an influence on behaviour shown in experimental scenarios. A practical implication of the findings for environmentally friendly design of consumer products is that there should be a stronger focus on system-based measures rather than information-based measures. Finally, the article discusses the theoretical implications of using operational scenarios rather than the information display board paradigm.

Adult↗
PubMed1989

Reproductive behaviour in poultry: implications for artificial insemination technology.

1. Reproductive ability requires both endocrine and behavioural components. 2. Most reproductive behaviour is dependent upon the presence of sufficient circulating concentrations of the gonadal steroids, which in turn are synthesised and secreted in individuals who are in good reproductive condition. Mating behaviour patterns are thus not only essential for reproduction, but can provide excellent indices of the reproductive ability of an individual. 3. A number of factors can suppress or enhance reproductive behaviour in poultry, including management practices, flock social interactions, environmental variables, stressors, and disease. 4. Aspects of the regulation of reproductive behaviour and the endocrine control of reproductive processes in the male and in the female are reviewed in this paper. 5. An understanding of the impact of social and environmental stressors on reproductive physiology and behaviour is extremely important, both in order to improve breeding efficiency in natural mating systems and to facilitate the most effective application of artificial insemination technology.

Animals↗
PubMed2000

Quantitative genetics of sexual plasticity: the environmental threshold model and genotype-by-environment interaction for phallus development in the snail Bulinus truncatus.

Sexual polymorphisms are model systems for analyzing the evolution of reproductive strategies. However, their plasticity and other binary traits have rarely been studied, with respect to environmental variables. A possible reason is that, although threshold models offer an adequate quantitative genetics framework for binary traits in a single environment, analyzing their plasticity requires more refined empirical and theoretical approaches. The statistical framework proposed here, based on the environmental threshold model (ETM), should partially fill this gap. This methodology is applied to an empirical dataset on a plastic sexual polymorphism, aphally, in the snail Bulinus truncatus. Aphally is characterized by the co-occurrence of regular hermaphrodites (euphallics) together with hermaphrodites deprived of the male copulatory organ (aphallics). Reaction norms were determined for 40 inbred lines, distributed at three temperatures, in a first experiment. A second experiment allowed us to rule out maternal effects. We confirmed the existence of high broad-sense heritabilities as well as a positive effect of high temperatures on aphally. However a significant genotype-by-environment interaction was detected for the first time, suggesting that sexual plasticity itself can respond to selection. A nested series of four ETM-like models was developed for estimating genetical effects on both mean aphally rate and plasticity. These models were tested using a maximum-likelihood procedure and fitted to aphally data. Although no perfect fit of models to data was observed, the refined versions of ETM models conveniently reduce the analysis of complex reaction norms of binary traits into standard quantitative genetics parameters, such as genetic values and environmental variances.

Animals↗
PubMed2006

Gene by environment QTL mapping through multiple trait analyses in blood pressure salt-sensitivity: identification of a novel QTL in rat chromosome 5.

BACKGROUND: The genetic mechanisms underlying interindividual blood pressure variation reflect the complex interplay of both genetic and environmental variables. The current standard statistical methods for detecting genes involved in the regulation mechanisms of complex traits are based on univariate analysis. Few studies have focused on the search for and understanding of quantitative trait loci responsible for gene x environmental interactions or multiple trait analysis. Composite interval mapping has been extended to multiple traits and may be an interesting approach to such a problem. METHODS: We used multiple-trait analysis for quantitative trait locus mapping of loci having different effects on systolic blood pressure with NaCl exposure. Animals studied were 188 rats, the progenies of an F2 rat intercross between the hypertensive and normotensive strain, genotyped in 179 polymorphic markers across the rat genome. To accommodate the correlational structure from measurements taken in the same animals, we applied univariate and multivariate strategies for analyzing the data. RESULTS: We detected a new quantitative train locus on a region close to marker R589 in chromosome 5 of the rat genome, not previously identified through serial analysis of individual traits. In addition, we were able to justify analytically the parametric restrictions in terms of regression coefficients responsible for the gain in precision with the adopted analytical approach. CONCLUSION: Future work should focus on fine mapping and the identification of the causative variant responsible for this quantitative trait locus signal. The multivariable strategy might be valuable in the study of genetic determinants of interindividual variation of antihypertensive drug effectiveness.

Animals↗
PubMed2001

Spatiotemporal dynamics of Floerkea proserpinacoides (Limnanthaceae), an annual plant of the deciduous forest of eastern North America.

Because environmental filters are temporally and spatially heterogeneous, there often is a lack of significant relationship between the spatial patterns of successive life stages in plant populations. In this study, we determined the spatiotemporal relationships between different life stages in two populations of an annual plant of the deciduous forests of eastern North America, Floerkea proserpinacoides. Demographic surveys were done over a 4-yr period, and experiments were performed in the field and under controlled conditions to test for the effects of various environmental factors on population dynamics. There was a general lack of relationship between the spatial patterns of seed bank and seedling density, and a lack of similarity between their spatial correlograms. This was related mostly to the effects of spatially variable environmental filters operating on germination and emergence. However, environmental filters acting on plant survival were stable through time and contributed to stabilize the density and spatial patterns of the populations. Despite density-dependent presenescence mortality, spatial patterns of seedlings and mature individuals were similar and their correlograms were alike, suggesting that mortality did not fully compensate for density. Estimated fecundity was negatively correlated with population density over the study period. Although flower production started only 2-3 wk after emergence, seed maturation mostly occurred at the end of the life cycle, just before the onset of plant senescence. Yet, individual fecundity was low for an annual plant, i.e., 3.0 ± 0.5 mature seeds/plant (mean ± 1 SE). Seed predation by vertebrates was not significant. Low soil moisture had little effect on the total number of seeds germinating, although it slowed down the germination process. In quadrats where leaf litter was experimentally doubled, seedling emergence was lower than in control quadrats; in quadrats where leaf litter was completely removed, emergence did not differ from that in control quadrats. Susceptibility to drought stress was higher for seedlings than for mature plants. Although the species does not maintain a long-term persistent soil seed bank, other factors, such as density-dependent fecundity and autogamy, may temper population fluctuations through time and reduce the probability of local extinction.

Journal Article↗
PubMed2004

Temperature and pH effects on plant uptake of benzotriazoles by sunflowers in hydroponic culture.

This article describes a systematic approach to understanding the effect of environmental variables on plant uptake (phyto-uptake) of organic contaminants. Uptake (and possibly phytotransformation) of xenobiotics is a complex process that may differ from nutrient uptake. A specific group of xenobiotics (benzotriazoles) were studied using sunflowers grown hydroponically with changes of environmental conditions including solution volume, temperature, pH, and mixing. The response of plants to these stimuli was evaluated and compared using physiological changes (biomass production and water uptake) and estimated uptake rates (influx into plants), which define the uptake characteristics for the xenobiotic. Stirring of the hydroponic solution had a significant impact on plant growth and water uptake. Plants were healthier, probably because of a combination of factors such as improved aeration and increase in temperature. Uptake and possibly phytotransformation of benzotriazoles was increased accordingly. Experiments at different temperatures allowed us to estimate an activation energy for the reaction leading to triazole disappearance from the solution. The estimated activation energy was 43 kJ/mol, which indicates that the uptake process is kinetically limited. Culturing plants in triazole-amended hydroponic solutions at different pH values did not strongly affect the biomass production, water uptake, and benzotriazole uptake characteristics. The sunflowers showed an unexpected capacity to buffer the solution pH.

Biodegradation, Environmental↗
PubMed1996

Development of a predictive model for growth of Listeria monocytogenes in a skim milk medium and validation studies in a range of dairy products.

A predictive model based on growth of Listeria monocytogenes in milk is described. The main aim of this work was to generate a predictive model in milk acidified with lactic acid to mimic conditions found in a range of dairy products. A complete factorial design was employed to determine the effects of pH (4.5-7.5), temperature (3-35 degrees C) and salt concentration (0-8%) on growth of the organism. There were 210 design points and growth curves were individually fitted for the Gompertz function using non-linear regression. Descriptors of the curves, such as lag phase duration (LPD), exponential growth rate (EGR) and generation time (GT) were calculated and polynomial models were developed relating these to pH, temperature and salt concentration. The selected cubic polynomial model gave acceptable predictive estimates of growth and was stable, i.e. predictions were repeatable over the range of environmental variables studied. The model was further tested to determine its capacity for predicting growth of listeria in a range of dairy foods and these validation studies confirm its usefulness as a rapid means of estimating growth of the organism under specified environmental conditions.

Animals↗
PubMed2005

Survey of stereotypic behavior in prosimians.

Captive animals have been observed to perform a variety of stereotypic behaviors. However, little is known about stereotypic behavior in prosimians. We sent surveys to 96 AZA-accredited institutions to examine stereotypic behavior in these primates. Forty-eight surveys were returned, providing information on 440 individuals of 10 genera. According to the responses, 13.2% of the prosimians surveyed exhibited some form of stereotypic behavior. Pacing was the most common behavior. A logistic regression was used to examine intrinsic characteristics that might influence the performance of stereotypic behavior. The genus of the prosimian was a significant predictor of stereotypic behavior. Individuals of the genus Varecia and Microcebuswere more likely to engage in stereotypic behavior than members of the other genera. Rearing history, age, and sex were not significant predictors of stereotypic behavior. To examine the influence of extrinsic variables on stereotypic behavior, we transformed the data into the percentage of individuals within the enclosure that were reported to exhibit stereotypic behavior, and analyzed them at the enclosure level using a general linear model (GLM) analysis of variance (ANOVA). The only environmental variable that significantly predicted stereotypic behavior was the frequency with which enrichment was provided. Frequent enrichment was provided to those exhibits with a higher percentage of prosimians that engaged in stereotypic behavior. The results of this survey suggest that stereotypic behavior in prosimians may be associated with intrinsic factors (i.e., individual or genus differences) in addition to extrinsic factors related to housing. This knowledge may be helpful in identifying the causes of and effective treatments for stereotypic behavior in prosimians.

Analysis of Variance↗
PubMed1987

Daily release of copper from dental alloy restorations in a patient with Wilson's disease.

Wilson's disease is a rare genetic disorder in which copper accumulates in tissues. Its victims must adhere to a strict dietary regimen yielding less than 2 mg of copper per day. Three major variables have been identified as being of critical importance in the treatment of these patients: the amount of copper naturally occurring in foods, the amount of copper introduced during the preparation of foods, and the amount of copper in the environment. An environmental variable that rarely has been addressed is the amount of copper in dental restorations. A case report is presented to discuss the possible consequences of copper-containing dental restorations for the patient with Wilson's disease.

Adult↗
PubMed2005

Discriminating between point and non-point sources of atrazine contamination of a sandy aquifer.

This study analyses the sources of atrazine contamination in the Brusselian sandy aquifer of central Belgium. Atrazine has in the past been used for both agricultural and non-agricultural applications, but it is difficult to distinguish the contamination originating from these two sources. The spatial and temporal covariance of atrazine concentrations was studied by fitting semi-variogram models to monitoring data. Correlation ranges were found to be 600 m and 600-700 days, respectively. The results were used to apply a declustering algorithm before examining the distribution of atrazine concentrations measured in groundwater. Monitoring data appeared to follow a pseudo-lognormal distribution, as a lognormality test was negative. An inflexion point on the cumulative density function was thought to indicate the two different pollution processes, i.e., agricultural and non-agricultural contamination sources. A non-parametric one-way analysis of variance suggested that the vast majority of atrazine in groundwater was from non-agricultural, point sources. This was supported by the strong relationship between mean concentrations and land use, whilst other environmental variables, such as soil organic matter or groundwater depth, produced less meaningful results.

Analysis of Variance↗
PubMed2004

Environmental split between germ cell parasitism and somatic cell synergism in chimeras of a colonial urochordate.

Colonies of the urochordate Botryllus schlosseri may fuse upon contact if they share common alleles on the highly polymorphic fusibility/histocompatibility locus. While, in these chimeras, one of the partners is usually morphologically eliminated (resorbed), circulating totipotent cells of the inferior genotype on the resorption phenomenon may parasitize either the soma or the germ line of the winner. Here, we show an environmental split of the two stem cell lineages that may develop germ cell parasitism vs somatic cell cooperation. Each naturally formed Botryllus chimera can be a composite of component genotypes created through two unlinked parasitic germ and somatic cell lineage interactions. The germ line parasitism is inherited through a pedigree. Conversely, by using amplified fragment length polymorphism (AFLP) and microsatellite alleles as polymorphic genetic markers, and seawater temperature as the variable environmental factor, we documented that the somatic constituent of chimeric zooids was shifted from one genotype to another, in accordance with the changes in seawater temperatures. This variable somatic state of chimerism in the field may, thus, carry benefits to the chimeral entity, which presents synergistically, at any time, the best-fitted combination of its genetic components.

Animals↗
PubMed1989

Inversion polymorphisms in Trimerotropis pallidipennis (Orthoptera): clinical variation along an altitudinal gradient.

Six populations of Trimerotropis pallidipennis located along an altitudinal gradient in the Antinaco-Los Colorados valley (La Rioja, Argentina), were cytologically analysed. The male karyotype consists of 23 chromosomes (22 + XO) with three long pairs submetacentric, the X-chromosome metacentric and the remaining ones basically acrocentric. Populations from La Rioja were polymorphic for seven pericentric inversions. Correlations between chromosome frequencies and altitude were statistically tested. In most cases, variables were either positively or negatively related in a significant fashion. As a consequence, mean populational heterozygosis (measured as the mean number of heteromorphic bivalents per individual per population) was also positively correlated with altitude. These results suggest that altitude (or other correlated environmental variable) may exert a differential selective pressure on coadapted gene blocks in the mutually inverted sequences. The possible relation of these results with the central-marginal model is discussed.

Altitude↗
PubMed2006

Multiscale drivers of water chemistry of boreal lakes and streams.

The variability in surface water chemistry within and between aquatic ecosystems is regulated by many factors operating at several spatial and temporal scales. The importance of geographic, regional-, and local-scale factors as drivers of the natural variability of three water chemistry variables representing buffering capacity and the importance of weathering (acid neutralizing capacity, ANC), nutrient concentration (total phosphorus, TP), and importance of allochthonous inputs (total organic carbon, TOC) were studied in boreal streams and lakes using a method of variance decomposition. Partial redundancy analysis (pRDA) of ANC, TP, and TOC and 38 environmental variables in 361 lakes and 390 streams showed the importance of the interaction between geographic position and regional-scale variables. Geographic position and regional-scale factors combined explained 15.3% (streams) and 10.6% (lakes) of the variation in ANC, TP, and TOC. The unique variance explained by geographic, regional, and local-scale variables alone was <10%. The largest amount of variance was explained by the pure effect of regional-scale variables (9.9% for streams and 7.8% for lakes), followed by local-scale variables (2.9% and 5.8%) and geographic position (1.8% and 3.7%). The combined effect of geographic position, regional-, and local-scale variables accounted for between 30.3% (lakes) and 39.9% (streams) of the variance in surface water chemistry. These findings lend support to the conjecture that lakes and streams are intimately linked to their catchments and have important implications regarding conservation and restoration (management) endeavors.

Carbon↗
PubMed1997

Reducing a spatial database to its effective dimensionality for logistic-regression analysis of incidence of livestock disease.

Large databases with multiple variables, selected because they are available and might provide an insight into establishing causal relationships, are often difficult to analyse and interpret because of multicollinearity. The objective of this study was to reduce the dimensionality of a multivariable spatial database of Zimbabwe, containing many environmental variables that were collected to predict the distribution of outbreaks of theileriosis (the tick-borne infection of cattle caused by Theileria parva and transmitted by the brown ear tick). Principal-component analysis and varimax rotation of the principal components were first used to select a reduced number of variables. The logistic-regression model was evaluated by appropriate goodness-of-fit tests.

Animals↗
PubMedDate not supplied

Hormesis: an adaptive expectation with emphasis on ionizing radiation.

Non-linear fitness gradients with maxima between extremes are expected for any environmental variable to which free-living populations are exposed. For exceedingly toxic agents, including ionizing radiation, such deviations from linearity are close to zero exposure and are conventionally called hormesis. Accordingly, hormesis is an extreme version of the non-linear fitness gradients for general environmental stresses such as temperature fluctuations, for which maximum fitness occurs at the moderate temperature fluctuations to which free-living populations are most commonly exposed. Some metabolic reserves should occur under moderate temperature stresses because of the need for pre-adaptation enabling survival during exposure to occasional periods of more extreme stress, especially at species borders where selection for stress resistance is likely to be most intense. Because heat shock proteins are induced by all stresses, adaptation to extreme temperatures should translate into adaptation to other stresses. Consequently, metabolic reserves from adaptation to extreme temperatures in the past should translate into protection from correlated abiotic stresses, especially in human populations where modern cultural processes are now ameliorating exposure to extreme stresses. Ambient and man-made radiations of non-catastrophic dimensions should therefore lead to stress-derived radiation hormesis. Other stresses can, in principle, be incorporated into this model. Accordingly, evolutionary and ecological considerations suggest two components of hormesis in relation to ionizing radiation: background radiation hormesis based upon the background exposure to which all organisms on earth are subjected; and stress-derived radiation hormesis. Exposure under stress-derived radiation hormesis is considerably larger than under background radiation hormesis, so significant deleterious effects from non-catastrophic radiation normally may be impossible to detect. Suggestions are provided for testing such postulated deviations from the commonly assumed linear no-threshold (LNT) hypothesis for the biological consequences of exposure to radiation.

Adaptation, Physiological↗