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PubMed2000

Magnesium in human milk.

Reported concentrations for magnesium in breast milk vary over a wide range (15 to 64 mg/L) with a median value of 31 mg/L and 75% of reported mean concentrations below 35 mg/L. Constitutional variables such as adolescent motherhood, gestation length, maternal undernutrition, metabolic disorders (diabetes, galactosemia), race, stage of lactation, sampling techniques (foremilk and hindmilk), as well as environmental variables such as socio-cultural diversity, smoking habits, dietary calcium and magnesium (including supplementation), vegetarianism, calciotropic agents (immunoreactive calcitonin, vitamin D), medication (hormonal contraceptives, magnesium sulfate) are critically reviewed in relation to changes in milk magnesium concentrations. Magnesium secretion into breast milk does not seem to be affected by the studied variables.

Environment↗
PubMed2003

Executive functioning in preschool-age children prenatally exposed to alcohol, cocaine, and marijuana.

BACKGROUND: Reports from clinical and experimental (animal) research converge on the suggestion that prenatal exposure to alcohol, cocaine, or marijuana undermines executive functioning (EF) and its neurological underpinnings. However, large, adequately controlled, prospective studies of alcohol and marijuana effects on EF have reported conflicting findings, and there have been no such studies of cocaine exposure. METHODS: EF was investigated in a cohort (n = 316) of 4-year-old children the majority of whose mothers had used varying combinations of cocaine, alcohol, and marijuana during pregnancy. With use of postpartum maternal report and biological assay, children were assigned to overlapping prenatal cocaine-exposed, alcohol-exposed, and marijuana-exposed groups and to complementary control groups. The postnatal environmental assessment included measures of maternal intellectual and psychosocial functioning, current drug or alcohol use, and home environment. RESULTS: The children in the alcohol-exposed group had worse tapping-inhibition performance than children in the non-alcohol-exposed group, and this effect persisted when potential confounding environmental variables, other drug variables, and concurrent verbal intelligence were controlled for. CONCLUSIONS: Prenatal alcohol is predictive of decreased EF in early childhood that could not be attributed to environmental factors. The results are discussed in terms of the age and overall high-risk status of the children.

Alcohol Drinking↗
PubMed2005

Pathogen adaptation to seasonal forcing and climate change.

Many diverse infectious diseases exhibit seasonal dynamics. Seasonality in disease incidence has been attributed to seasonal changes in pathogen transmission rates, resulting from fluctuations in extrinsic climate factors. Multi-strain infectious diseases with strain-specific seasonal signatures, such as cholera, indicate that a range of seasonal patterns in transmission rates is possible in identical environments. We therefore consider pathogens capable of evolving their 'seasonal phenotype', a trait that determines the sensitivity of their transmission rates to environmental variability. We introduce a theoretical framework, based on adaptive dynamics, for predicting the evolution of disease dynamics in seasonal environments. Changes in the seasonality of environmental factors are one important avenue for the effects of climate change on disease. This model also provides a framework for examining these effects on pathogen evolution and associated disease dynamics. An application of this approach gives an explanation for the recent cholera strain replacement in Bangladesh, based on changes in monsoon rainfall patterns.

Adaptation, Physiological↗
PubMed2007

An analysis of pre- and post-hatching maternal effects mediated by carotenoids in the blue tit.

Maternal effects increase phenotypic plasticity in offspring traits and may therefore facilitate adaptation to environmental variability. Carotenoids have been hypothesized to mediate costs of reproduction in females as well as maternal effects. However, assessing potential transgenerational and population consequences of environmental availability of carotenoids requires a better understanding of mechanisms of maternal effects mediated by these antioxidant pigments. Manipulating dietary availability of carotenoids to egg-laying female blue tits and subsequently cross-fostering nestlings between female treatments allowed us to specifically investigate the relative importance of maternal effects through egg carotenoids and through post-hatching care mediated by antioxidants in females. Nestling body size and mass and plasma antioxidants were not significantly affected by pre- or post-hatching maternal effects mediated by antioxidants, although both types of maternal effects in interaction explained the variation in growth, as measured by wing length. Development of the ability to mount a cell-mediated immune response as well as its temporal dynamics was influenced by both pre- and post-hatching maternal effects, with an advantage to nestlings originating from, or reared by, carotenoid-supplemented females. In addition, nestlings reared by carotenoid-fed females had a lower blood sedimentation rate, indicating that they may have been less infected than nestlings from controls. Finally, prehatching maternal effects in interaction with nestling plasma carotenoid levels affected the development of carotenoid-based plumage. Maternal effects mediated by carotenoids may thus act as a proximate factor in development and phenotypic plasticity in traits associated with nestling fitness, such as immune response and ability to metabolize and use antioxidants, and ultimately participate in the evolution of phenotypic traits.

Animals↗
PubMed2000

Pathogenic clones versus environmentally driven population increase: analysis of an epidemic of the human fungal pathogen Coccidioides immitis.

For many pathogenic microbes that utilize mainly asexual modes of reproduction, it is unknown whether epidemics are due to either the emergence of pathogenic clones or environmentally determined increases in the population size of the organism. Descriptions of the genetic structures of epidemic populations, in conjunction with analyses of key environmental variables, are able to distinguish between these competing hypotheses. A major epidemic of coccidioidomycosis (etiologic agent, Coccidioides immitis) occurred between 1991 and 1994 in central California, representing an 11-fold increase above the mean number of cases reported from 1955 to 1990. Molecular analyses showed extensive genetic diversity, a lack of linkage disequilibria, and little phylogenetic structure, demonstrating that a newly pathogenic strain was not responsible for the observed epidemic. Epidemiological analyses showed that morbidity caused by C. immitis was best explained by the interaction between two variables, the lengths of droughts preceding epidemics and the amounts of rainfall. This shows that the principal factors governing this epidemic of C. immitis are environmental and not genetic. An important implication of this result is that the periodicity of cyclical environmental factors regulates the population size of C. immitis and is instrumental in determining the size of epidemics. This knowledge provides an important tool for predicting outbreaks of this pathogen, as well as a general framework that may be applied to determine the causes of epidemics of other fungal diseases.

Coccidioides↗
PubMed2001

Phytoplankton and water quality characterization: experiences from the Swedish large lakes Mälaren, Hjälmaren, Vättern and Vänern.

Phytoplankton and environmental variables have been monitored in the large Swedish lakes Mälaren, Hjälmaren, Vättern and Vänern since the 1960s. Measures to reduce phosphorus input and industrial waste products were taken during the 1970s. The phosphorus loading was then reduced by 90-95% resulting in a halving of the phosphorus concentrations in the most affected basins. The phytoplankton community reacted rapidly with decreased biomasses of cyanobacteria in summer as well as decreased biomasses of spring diatoms and cryptophycean flagellates. Other reactions were a contracted period of water-bloom, an increased taxon richness, an increased evenness in the biomass over the growth season, and a change in the species size structure within the phytoplankton community. Furthermore, the species richness in the large lakes is compared in relation to lake characteristics. A presentation of the occurrence of toxic cyanobacteria in the lakes is also given. Maximum-minimum values of 13-0.1 micrograms microcystin L-1 are established in connection with water-blooms in Hjälmaren and Mälaren. The use of phytoplankton as a monitoring variable to detect water-quality changes is outlined and assessment criteria are presented.

Ecosystem↗
PubMed1998

Cemented femoral stem performance. Effects of proximal bonding, geometry, and neck length.

The effects of proximal bonding, distal stem geometry, and femoral neck length on cement and interface stresses were determined to understand better their role in clinical performance. The effects of stem design were compared with the effects of environmental variables, patient weight, and patient activity. Finite element models were used to determine peak cement and interface stresses, and an experimental layout was used to separate design and environmental effects. Bonding reduced cement mantle stresses by 35% to 60%, to levels below the cement fatigue strength. A flat sided implant provided more torsional resistance, reducing shear stresses at the proximal cement-prosthesis interface by 22% to 73% with respect to a distal round implant. Neck length had minimal effects on stresses compared with bonding or implant geometry. Cement-bone interface stresses were more sensitive to patient activity than to the design variables. Therefore, claims that a strong cement and prosthesis bond may be harmful to the bone-cement interface are unjustified based on these results. The best combination of design variables was a proximally bonded, flat sided implant with neck length left to the surgeon's discretion. This combination was most effective at protecting the cement mantle and prosthesis interface and perhaps the cement-bone interface by minimizing stresses associated with cement debris generation.

Activities of Daily Living↗
PubMed2004

Relationship between latex yield of Hevea brasiliensis and antecedent environmental parameters.

A study on the relationship between latex yield and antecedent environmental data was undertaken for five clones (RRII203, RRII118, RRIM600, RRII105 and GT1) of Hevea brasiliensis (rubber) in Agartala, northeast India, a region in which rubber is not traditionally cultivated. The explained variance for the regression equations based on parameters determined on the day of tapping and up to 3 days prior to it, varied from 72% to 37% during the NWT period and 94-83% during the WT period. Soil moisture storage, 1 and 3 days prior to tapping, was found to be the primary parameter affecting yield for the NWT and WT periods, respectively. It was observed that the clone RRII105, with a comparatively lower yield to that of RRIM600, was more susceptible to daily WD conditions during the non-winter season. RRIM600 and RRII105 being high-yielding clones were also found to be fairly dependent on the AT of the day prior to tapping. The mean lag period correlation of this parameter with yield was also found to be higher during the WT period than during the NWT period. As a whole, the mean lag period based on prior measurements of environmental variables showed optimum correlation with yield at 15-20 days prior to the day of tapping. The study also confirms that varied responses of yield with environmental factors in this non-traditional region of rubber cultivation depend on clonal character.

Environment↗
PubMed2001

Family environmental factors influencing the developing behavioral controls of food intake and childhood overweight.

Although a large body of research has assessed direct genetic links between parent and child weight status, relatively little research has assessed the extent to which parents (particularly parents who are overweight) select environments that promote overweight among their children. Parents provide food environments for their children's early experiences with food and eating. These family eating environments include parents' own eating behaviors and child-feeding practices. Results of the limited research on behavioral mediators of familial patterns of overweight indicate that parents' own eating behaviors and their parenting practices influence the development of children's eating behaviors, mediating familial patterns of overweight. In particular, parents who are overweight, who have problems controlling their own food intake, or who are concerned about their children's risk for overweight may adopt controlling child-feeding practices in an attempt to prevent overweight in their children. Unfortunately, research reveals that these parental control attempts may interact with genetic predispositions to promote the development of problematic eating styles and childhood overweight. Although the authors have argued that behavioral mediators of family resemblances in weight status, such as parents' disinhibited or binge eating and parenting practices are shaped largely by environmental factors, individual differences in these behaviors also have genetic bases. A primary public health goal should be the development of family-based prevention programs for childhood overweight. The findings reviewed here suggest that effective prevention programs must focus on providing anticipatory guidance on parenting to foster patterns of preference and food selection in children more consistent with healthy diets and promote children's ability to self-regulate intake. Guidance for parents should include information on how children develop patterns of food intake in the family context. Practical advice for parents includes how to foster children's preferences for healthy foods and how to promote acceptance of new foods by children. Parents need to understand the costs of coercive feeding practices and be given alternatives to restricting food and pressuring children to eat. Providing parents with easy-to-use information regarding appropriate portion sizes for children is also essential as are suggestions on the timing and frequency of meals and snacks. Especially during early and middle childhood, family environments are the key contents for the development of food preferences, patterns of food intake, eating styles, and the development of activity preferences and patterns that shape children's developing weight status. Designing effective prevention programs will, however, require more complete knowledge than currently available regarding behavioral intermediaries that foster overweight, including the family factors that shape activity patterns, meals taken away from home, the impact of stress on family members' eating styles, food intake, activity patterns, and weight gain. The research presented here provides an example of how ideas regarding the effects of environmental factors and behavioral mediators on childhood overweight can be investigated. Such research requires the development of reliable and valid measures of environmental variables and behaviors. Because childhood overweight is a multifactorial problem, additional research is needed to develop and test theoretic models describing how a wide range of environmental factors and behavioral intermediaries can work in concert with genetic predispositions to promote the development of childhood overweight. The crucial test of these theoretic models will be in preventive interventions.

Adult↗
PubMed2003

The amplification of environmental noise in population models: causes and consequences.

Environmental variability is a ubiquitous feature of every organism's habitat. However, the interaction between density dependence and those density-independent factors that are manifested as environmental noise is poorly understood. We are interested in the conditions under which noise interacts with the density dependence to cause amplification of that noise when filtered by the system. For a broad family of structured population models, we show that amplification occurs near the threshold from stable to unstable dynamics by deriving an analytic formula for the amplification under weak noise. We confirm that the effect of noise is to sustain oscillations that would otherwise decay, and we show that it is the amplitude and not the phase that is affected. This is a feature noted in several recent studies. We study this phenomenon in detail for the lurchin and LPA models of population dynamics. We find that the degree of amplification is sensitive to both the noise input and life-history stage through which it acts, that the results hold for surprisingly high levels of noise, and that stochastic chaos (as measured by local Lyapunov exponents) is a concomitant feature of amplification. Further, it is shown that the temporal autocorrelation, or "color," of the noise has a major impact on the system response. We discuss the conditions under which color increases population variance and hence the risk of extinction, and we show that periodicity is sharpened when the color of the noise and dynamics coincide. Otherwise, there is interference, which shows how difficult it is in practice to separate the effects of nonlinearity and noise in short time series. The sensitivity of the population dynamics to noise when close to a bifurcation has wide-ranging consequences for the evolution and ecology of population dynamics.

Animals↗
PubMed2006

Population characteristics predict responses in moose body mass to temporal variation in the environment.

1. A general problem in population ecology is to predict under which conditions stochastic variation in the environment has the stronger effect on ecological processes. By analysing temporal variation in a fitness-related trait, body mass, in 21 Norwegian moose Alces alces (L.) populations, we examined whether the influence of temporal variation in different environmental variables were related to different parameters that were assumed to reflect important characteristics of the fundamental niche space of the moose. 2. Body mass during autumn was positively related to early access to fresh vegetation in spring, and to variables reflecting slow phenological development (low June temperature, a long spring with a slow plant progression during spring). In contrast, variables related to food quantity and winter conditions had only a minor influence on temporal variation in body mass. 3. The magnitude of the effects of environmental variation on body mass was larger in populations with small mean body mass or living at higher densities than in populations with large-sized individuals or living at lower densities. 4. These results indicate that the strongest influence of environmental stochasticity on moose body mass occurs towards the borders of the fundamental niche space, and suggests that populations living under good environmental conditions are partly buffered against fluctuations in environmental conditions.

Animals↗
PubMed2005

Sample phenotype clusters in high-density oligonucleotide microarray data sets are revealed using Isomap, a nonlinear algorithm.

BACKGROUND: Life processes are determined by the organism's genetic profile and multiple environmental variables. However the interaction between these factors is inherently non-linear. Microarray data is one representation of the nonlinear interactions among genes and genes and environmental factors. Still most microarray studies use linear methods for the interpretation of nonlinear data. In this study, we apply Isomap, a nonlinear method of dimensionality reduction, to analyze three independent large Affymetrix high-density oligonucleotide microarray data sets. RESULTS: Isomap discovered low-dimensional structures embedded in the Affymetrix microarray data sets. These structures correspond to and help to interpret biological phenomena present in the data. This analysis provides examples of temporal, spatial, and functional processes revealed by the Isomap algorithm. In a spinal cord injury data set, Isomap discovers the three main modalities of the experiment--location and severity of the injury and the time elapsed after the injury. In a multiple tissue data set, Isomap discovers a low-dimensional structure that corresponds to anatomical locations of the source tissues. This model is capable of describing low- and high-resolution differences in the same model, such as kidney-vs.-brain and differences between the nuclei of the amygdala, respectively. In a high-throughput drug screening data set, Isomap discovers the monocytic and granulocytic differentiation of myeloid cells and maps several chemical compounds on the two-dimensional model. CONCLUSION: Visualization of Isomap models provides useful tools for exploratory analysis of microarray data sets. In most instances, Isomap models explain more of the variance present in the microarray data than PCA or MDS. Finally, Isomap is a promising new algorithm for class discovery and class prediction in high-density oligonucleotide data sets.

Algorithms↗
PubMed1983

Familial aggregation of blood pressure and weight in adoptive families. III. Analysis of the role of shared genes and shared household environment in explaining family resemblance for height, weight and selected weight/height indices.

This study presents an analysis of the role of genetic and household environment in explaining the familial aggregation of height (HT), weight (WT), and body mass indices (WT/HT1.2 and WT/HT2.0). The biologic model used for the analysis partitions the covariances between family members into the contributions of genetic and environmental variability shared within and across generations, including a variance component shared only by a mother and her natural children. Tests of hypotheses suggest that shared genes and shared household environmental factors make significant contributions to the familial aggregation of WT (adjusted for age and sex) and of HT (adjusted for age and sex), whereas family resemblance of WT adjusted for age and HT can be attributed mostly to the effects of shared genes. The familial aggregation of selected WT/HT indices is attributed to the effects of shared household environment only, suggesting that these variables measure a characteristic of stature that is independent of height and weight.

Adolescent↗
PubMedDate not supplied

[Standardised environmental conditions for neurocognitive laboratories].

INTRODUCTION AND AIMS: The exploration of neurocognition in neurology departments has gone a long way from the traditional psychometric tests to the present day use of high technology methods in cognitive neurophysiology, as is the case of event related potentials. Given the increased sensitivity of these procedures, it has become absolutely essential to control the influence of environmental variables that may exert non controlled effects on the patient s response. Many neurocognitive laboratories have been set up in premises in which the spatial layout and the environmental characteristics have been determined beforehand and consequently technical staff has had to prepare these rooms in an empirical way. This gives rise to two types of drawbacks: interferences in the patient s concentration and low reproducibility of the results in other laboratories. METHOD: In this paper we present a proposed set of standardised conditions for a neurocognitive laboratory from an architectural perspective, and more specifically with regard to interior design. We outline the functional design of the premises, the conditions for workplaces where VDU computers (Video Display Units) are used and where psychometric evaluation is carried out. We also discuss the criteria to be followed when placing the laboratory within a hospital, lighting parameters, air conditioning and suggestions about psychological input. CONCLUSIONS: Although we do not seek to establish a rigid set of norms, these conditions will raise the quality of evaluations and facilitate the comparison of results because of the reduced variability from the environment.

Architecture↗
PubMed1982

An ecological model of mental health among small-town rural elderly.

The present study models the impact of three domains of environmental variables (ecological/architectural, psychosocial, and personal) on the mental health and well-being of 989 community-based rural elderly (65 years or older) in 18 small Kansas towns. Utilizing standard structured interview data, we employed a holdout sample strategy to test a path model that posited three psychosocial variables as partially mediating the predictive relations of two ecological/architectural and three personal variables with mental health. Results of tests of the model confirmed the statistical reliability (p less than .05) of all relations posited for mental health, with perceived environmental constriction, satisfaction with dwelling features, and satisfaction with community serving as the largest predictors. Results showed the decreasing predictive efficacy of the model for other dimensions of well-being (activity, security, contact with friends, contact with relatives). Strengths and weaknesses of the model relevant to conceptual, emphirical, and interventive pursuits are discussed.

Aged↗
PubMed1992

Environmental and personality differences between children of alcoholics and their peers.

Nonclinical, adolescent children of alcoholics (COAs) and their peers from nonalcoholic homes (CONAs) responded to questionnaires of environmental variables, depression, and anxiety. Multivariate (discriminant) analyses revealed several meaningful differences between the two groups. Although the two groups differed on the measures of anxiety and depression, environmental stressors contributed most to the discriminant function that differentiated between the two groups. Also, gender differences were discovered, suggesting that males and females perceive problem drinking differently and that home environments may be different for the two genders. Implications for research and intervention are discussed.

Adolescent↗
PubMed1989

Physiological adaptation to the environment.

The ability of an animal to cope with new environments arises from its capacity to respond to environmental variables and maintain body equilibrium (homeostasis). Each compensating mechanism depends on, and is a part of, a physiological feedback process. The severity (intensity and duration) of an environmental change relative to the animal's capacity to respond determines the potential disruption to the animal's equilibrium and the resources that must be invested to regain homeostasis. However, an environmental change sufficient to seriously challenge one individual may be insufficient to produce a measurable response in another. The principles behind the responses occurring in animals as a consequence of a change in their physical environment are illustrated in this review by examples drawn from responses of animals to cold stress. Behavioral opportunities sometimes are constrained in farm animals, and internal metabolic responses tend to become more prominent in such situations. Furthermore, as a disturbing factor persists, the immediate defensive responses are replaced by longer-term and adaptive mechanisms that reduce the burden on the animal. As we gain greater understanding of the environment-animal interface and the sensitivity and response of animals to disruption, we will be better able to establish and maintain suitable environments for our farm animals.

Adaptation, Physiological↗
PubMed2005

Distribution of Neoparamoeba sp. in sediments around marine finfish farming sites in Tasmania.

Marine sediment samples collected from various sites at 2 Atlantic salmon farms in Tasmania were analysed for the presence of Neoparamoeba sp., an amoeba associated with amoebic gill disease (AGD) in farmed Atlantic salmon. Environmental variables of the sediment layer at each site, including redox potential and sulphide concentration, were measured and the general biological condition assessed by video observation. Sediments and environmental data were collected on 4 occasions at each site over a 12 mo period. Neoparamoeba sp. was detected in populations of amoebae recovered by culture from all sites and in 50% of all sediment samples taken. There was evidence of a seasonal influence on the presence of the amoeba, but this was different at each farm. No Neoparamoeba sp. was recovered from any sites at Farm 1 during the winter of 2002 whereas at Farm 2 this was the case for the summer of 2003. There appeared to be no relationship between the presence of Neoparamoeba sp., salmon farming activities and environmental parameters.

Animals↗