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Results for “environmental variability”

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PubMed2004

Methylenetetrahydrofolate reductase (MTHFR) c677t gene variant modulates the homocysteine folate correlation in a mild folate-deficient population.

BACKGROUND: A large body of evidence links plasma concentrations of homocysteine and cardiovascular disease. Several genetic and environmental variables may modulate such relationship. We investigated the influence of methylenetetrahydrofolate reductase (MTHFR) gene variants C677T, A1298C, and T1317C on homocysteine, folate, and cobalamin concentrations in a sample of individuals from a mild folate deficiency population to better clarify the complex interactions existing among these variables. METHODS: In the present study, 209 individuals belonging to an admixed urban population characterized by mild folate deficiency were investigated. MTHFR gene variants C677T, A1298C, and T1317C were genotyped and homocysteine-, folate-, and cobalamin-determined for each individual. RESULTS: Univariate analyses showed a significant association between the C677T variant with homocysteine (P<0.001) and cobalamin (P=0.005) as well as a significant relationship between the T allele and serum folate concentrations (P<0.05). The TT genotype of the C677T polymorphism remained significantly associated with log-transformed homocysteine even after adjustment for age, sex, smoking status, ethnicity, folate, and cobalamin concentrations (P<0.01). Both univariate and multivariate analysis have failed to show any effect of the A1298C and T1317C genetic variants in homocysteine concentrations in this population. Finally, a significant interaction between folate and C677T polymorphism in the determination of homocysteine was also disclosed (P<0.005). CONCLUSIONS: Taken together, these results demonstrate a significant interaction between serum folate and MTHFR genotype in predicting homocysteine concentrations. One may consider that a differential response of homocysteine to folic acid supplementation may depend on MTHFR genotype which may have important implications when attempting to lower homocysteine concentrations in populations with mild folate deficiency.

Adult↗

PubMed2006

Apolipoprotein E polymorphism in the Tunisian population: frequency and effect on lipid parameters.

OBJECTIVES: We determined the frequencies of apolipoprotein E (apo E) gene alleles and examined the association between apo E polymorphism and lipid parameters in a sample of the Tunisian population. DESIGN AND METHODS: Apo E polymorphism was investigated using PCR, and plasma lipid parameters were measured in 122 men and 111 women aged 35 to 87 years. RESULTS: The allele frequencies were epsilon2: 7.3%, epsilon3: 84.6%, and epsilon4: 8.1%. Apo E polymorphism was associated with significant differences (P<0.001) in total cholesterol, apo B and LDL cholesterol in both men and women. epsilon2 carriers had the lowest mean total cholesterol, apo B and LDL-C concentrations, and subjects with the epsilon4 allele had the highest levels. Triglycerides levels increased with the epsilon4 allele, but this did not reach statistical significance. These results remained unchanged after adjustment for age, body mass index, sex, hypertension, diabetes and smoking. However, in obese subjects (BMI>30 kg/m2), TG concentrations were significantly lower in individuals homozygous for the epsilon3 allele compared to those with the alleles epsilon2 or epsilon4. CONCLUSION: In this sample of the Tunisian population, the distribution of apo E gene alleles is similar to that observed in Southern European populations with low prevalence of the epsilon4 allele. Variations in the apo E gene play a role in determining plasma lipid levels. These data also suggest that effects of apo E alleles on lipids levels are partly dependent on environmental variables such as BMI. These findings highlight the importance of the gene/environment interaction on the deleterious effect of obesity on cardiovascular risk factors.

Adult↗

PubMed2006

Behavioral motifs and neural pathways coordinating O2 responses and aggregation in C. elegans.

BACKGROUND: Simple stimuli can evoke complex behavioral responses coordinated by multiple neural circuits. O(2) is an important environmental variable for most animals. The nematode C. elegans avoids high O(2), and O(2) levels regulate its foraging and aggregation. RESULTS: Here, we dissect aggregation and responses to O(2) gradients into behavioral motifs and show how O(2) responses can promote aggregation. To remain in a group, C. elegans continually modify their movement. Animals whose heads emerge from a group will reverse or turn, thereby returning to the group. Re-entry inhibits further reversal, aiding retention in the group. If an animal's tail exits a group during a reversal, it switches to forward movement, returning to the group. Aggregating C. elegans locally deplete O(2). The rise in O(2) levels experienced by animals leaving a group induces both reversal and turning. Conversely, the fall in O(2) encountered when entering a clump suppresses reversal, turning, and high locomotory activity. The soluble guanylate cyclases GCY-35 and GCY-36, which are expressed in head and tail neurons, promote reversal and turning when O(2) rises. Avoidance of high O(2) is also promoted by the TRP-related channel subunits OCR-2 and OSM-9, and the transmembrane protein ODR-4, acting in the nociceptive neurons ASH and ADL. Both O(2) responsiveness and aggregation can be modified by starvation, but this is regulated by natural variation in the npr-1 neuropeptide receptor. CONCLUSIONS: Our work provides insights into how a complex behavior emerges from simpler behavioral motifs coordinated by a distributed circuit.

Animals↗

PubMed2004

Effect of light, temperature, and pH on the accumulation of phenol by Selenastrum capricornutum, a green alga.

The role of light, temperature, and pH was evaluated on the accumulation of phenol by the green alga, Selenastrum capricornutum. All three environmental variables had a significant effect on the accumulation of phenol. Differences in phenol accumulation were observed in algae that were cultured under light or dark conditions. In the light tests, the accumulation of phenol over a temperature range of 12-28 degrees C was unimodal while in the dark test accumulation exhibited a monotonic relationship with temperature. Differences in accumulation were not simply a function of algal growth or biomass. A unimodal relationship was also observed in the pH experiments with the maximal phenol accumulation in algae occurring at pH 6 and the least at pH 10. Temperature also influenced the accumulation of phenol by algae in the pH tests. As was determined in the light tests, biomass or cell growth was not a significant factor in determining the extent of accumulation in these studies. The results from this study demonstrate that accumulation of organics by algae is not simply a partitioning process but one that can be influenced by the interaction of biotic and abiotic variables.

Analysis of Variance↗

PubMed2006

Calibration and field performance of membrane-enclosed sorptive coating for integrative passive sampling of persistent organic pollutants in water.

Membrane-enclosed sorptive coating (MESCO) is a miniaturised monitoring device that enables integrative passive sampling of persistent, hydrophobic organic pollutants in water. The system combines the passive sampling with solventless preconcentration of organic pollutants from water and subsequent desorption of analytes on-line into a chromatographic system. Exchange kinetics of chemicals between water and MESCO was studied at different flow rates of water, in order to characterize the effect of variable environmental conditions on the sampler performance, and to identify a method for in situ correction of the laboratory-derived calibration data. It was found that the desorption of chemicals from MESCO into water is isotropic to the absorption of the analytes onto the sampler under the same exposure conditions. This allows for the in situ calibration of the uptake of pollutants using elimination kinetics of performance reference compounds and more accurate estimates of target analyte concentrations. A field study was conducted to test the sampler performance alongside spot sampling. A good agreement of contaminant patterns and water concentrations was obtained by the two sampling techniques.

Adsorption↗

PubMed2004

Psychosis, migration and social environment: an age--and--gender controlled study.

PURPOSE: Adverse social experiences are frequently invoked to explain the higher rate of psychosis among migrant groups. The aim of the present study was to establish the socio-environmental factors distinguishing migrant psychotic patients from autochthonous patients. SUBJECTS AND METHOD: We conducted a cross-sectional survey involving 341 migrant psychotic patients matched for age and gender with 341 autochthonous psychotic patients. RESULTS: Migrant patients lived more often with their parental family, were less often enrolled with a referral psychiatrist, presented a lower rate of employment, a lower percentage of alcohol misuse and of suicide attempts. DISCUSSION: Our findings add to the growing body of results showing that more attention needs to be focused on socio-environmental variables in psychosis research. However, several limitations have to be taken into account, particularly with regard to selection biases and age of onset of the psychotic illness. CONCLUSION: Our results are compatible with the hypothesis that unemployment is a contributing factor in the risk for psychosis among migrant groups. Migrants' families are an important keystone in the mental health care process of their sick relatives. Our service models need to be adapted with the aim to make the treatment easier for migrant patients.

Adult↗

PubMed2026

Forensic taphonomy in fluvial water: A systematic review.

Human remains are frequently recovered from fluvial (lotic) water environments. Rivers, streams, canals and other flowing water bodies pose distinct challenges in forensic practice, particularly due to their current. Compared to other aquatic contexts, fluviatile taphonomy is underrepresented in the forensic literature and the last comprehensive summary was written over a decade ago. Therefore, a systematic review was performed to collect and summarise the current knowledge in forensics about fluvial taphonomy, including decomposition of remains, transport characteristics, search, postmortem submersion interval (PMSI) estimation, taphonomic alterations, and differences to other water bodies. 92 reports met the inclusion criteria for this review, most of them showed a moderate risk of bias. Their main findings were summarised and two major challenges identified. First, predictions about fluvial transport of human bodies pose a tremendous issue in forensic practice, leading to later detection and lower recovery rate of remains, complicating various subsequent analyses. Second, PMSI estimations are difficult particularly due to variable environmental conditions in fluviatile systems. Recommendations for future research in the area of fluvial forensic taphonomy include that case-related data such as the detailed decomposition state and river characteristics need to be made available. More standardised research protocols are required for a facilitated comparison between studies, environments and regions. This review provides forensic practitioners with a comprehensive, updated resource for the investigation of fluvial remains. It also guides future research towards a more efficient practice to build the basis for a broader, more robust and comprehensive synthesis, subsequently supporting analyses in forensic casework.

Humans↗

PubMed2004

Intra-urban differentials in child dental trauma in relation to healthy cities policies in Curitiba, Brazil.

This paper is concerned with developing methods for assessing the potential impact of healthy public policies on health outcomes, particularly on dental trauma. The hypothesis is that in deprived areas of Curitiba, Brazil, there would be a lower prevalence of dental trauma in 12-year-old schoolchildren related to different degrees of implementation of healthy public policies. Fourteen socio-environmental variables gathered from 29 deprived areas were factor-analysed and three principal components (PCA) extracted: physical environment, public social policies, and social cohesion. Individual clinical data on dental trauma were collected for 2,126 children from public schools in the areas. Rank correlation indicated that the relationship between components' scores and dental trauma was statistically significant. The PCA scores explained 42% of the variance for dental trauma.

Brazil↗

PubMedDate not supplied

Correlates of health-related quality of life among lower-income, urban adults with congestive heart failure.

BACKGROUND: Improving health-related quality of life (HRQL) is a primary goal in the treatment of patients with congestive heart failure (CHF), yet few studies have explored correlates of HRQL among CHF patients. OBJECTIVES: We report on the association of demographic and pathophysiologic measures, social-cognitive measures, and environmental variables with HRQL as measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ), Chronic Heart Failure (CHQ), and a single question of perceived overall health (PH). METHODS: Cross-sectional data were obtained from the baseline interview and electronic medical records of 212 patients 50 years of age and older who were enrolled during the first 7 months of a medication adherence study. RESULTS: Mean age was 63; 32% were male; 53% were black; the mean Charlson comorbidity score was 3.7; and the mean New York Heart Association class was 2.1. Correlations between KCCQ and CHQ subscale scores and PH ranged from 0.16 to 0.37. Multivariate regression analyses showed that the pathophysiologic measures ejection fraction and comorbidity were not associated with any of the HRQL measures. Overall PH was associated with greater age and more positive health beliefs. Persons of greater age, males, and black respondents had higher CHF-specific HRQL scores, as did persons reporting more positive health beliefs, greater income, social support, and communication with their physician. Variance explained ranged from 14 to 33%. CONCLUSION: These cross-sectional data highlight the potential significance of social and behavioral factors in CHF-specific HRQL.

Age Factors↗

PubMed2004

Allergic symptoms and microflora in schoolchildren.

We studied 867 junior high school children and administered a questionnaire documenting allergic symptoms and environmental variables, and measured Immunoglobulin E serum levels and the immunoglobulin G titers of serum antibody to microflora. A total of 716 subjects were ultimately used for statistics; those with at least two of the following allergic symptoms: asthma, rhinitis, eczema, or food allergy, showed significantly higher IgG titers to Bactroides vulgatus than other groups. This finding suggests that a species of the Bacteroides genus of the intestinal microflora tends to affect the gut issues, but further studies are needed to clarify this.

Adolescent↗

PubMed2006

Piezophilic adaptation: a genomic point of view.

Two-thirds of Earth's surface is covered by oceans, yet the study of this massive integrated living system is still in its infancy. Various environmental variables, such as high salinity, low and changeable nutrient availability and depth-correlated gradients of light, temperature, nutrients and pressure shape the diversity, physiology and ecology of marine species. As oceans present an average depth of 3800 m, deep-sea ecosystems represent the most common marine ecological niche. One of the key environment variables that influences the life and evolution of deep-sea organisms is high pressure. This extreme widespread condition requires specific adaptations, the nature of which remains largely unknown. Recent advances in genomic approaches, such as in sequencing technologies and global expression profiling, are rapidly increasing the data available to understand microbial evolution, biochemistry, physiology and diversity. This review summarises the analysis of the results published so far about microbial high pressure adaptation from a genomic point of view. Understanding high pressure adaptation mechanisms is not just a scientific exercise but has important biotechnological implications. For example, hydrostatic pressure is a reality for food science and technology, both for food preparation and preservation. An understanding of the effects of pressure on biomolecules will expand its use in the medical, industrial and biotechnological fields.

Acclimatization↗

PubMed2004

The localized environmental degradation of protected areas adjacent to bird feeding stations: a case study of the Australian brush-turkey Alectura lathami.

This study investigated the potential for wildlife feeding to artificially increase population densities of the Australian brush-turkey, Alectura lathami and assessed the indirect adverse effects that this may have on surrounding forest floor vegetation. Census counts and observations of feeding activity conducted in recreation areas of Australia's Gold Coast hinterland confirmed that brush-turkey population densities were significantly elevated by the provision of food by humans. Brush-turkey densities were high at sites where birds are actively fed, moderate at sites where birds feed opportunistically and low at sites where humans have negligible impact on local food availability. Brush-turkeys caused significant environmental impact at sites where their population densities have been substantially elevated by active feeding. Across all sites, increases in brush-turkey density were accompanied by a significant decline in ground cover, leaf litter weight, seed density and seedling density. Natural environmental variables such as gradient, vegetation type and canopy cover did not explain the observed impacts. The impacts were consistent with those described in trampling studies and suggest that at high density, even small animals can have significant trampling impacts on their local environment. This study demonstrates that wildlife feeding can have detrimental impacts on the integrity of local environments and recommends greater consideration of small animals and their potential indirect impacts when regulating wildlife feeding in National Parks and other nature conservation areas.

Animal Feed↗

PubMed2005

Assessment of the rangelands of southwestern Santiago del Estero, Argentina, for grazing management and research.

Native rangelands of the southwest part of the province of Santiago del Estero, Argentina, are a key source of forage for cow-calf operations. The objectives of this study were to delineate the ecosystem units of the area, to describe the associated plant communities and to interpret the role that physical factors and disturbances such as fire and grazing have had in the changes of the structure of these plant communities. This information is needed for developing recommendations for grazing management, for prescribing appropriate improvement practices (e.g. shrub control, prescribed fire) and as guidelines for future research. The ecosystem was divided into smaller units using a hierarchical method, the categories of practical importance being 'range unit' and 'range site'. They represent the catchment and hillslope scale of the water runoff-runon phenomenon, respectively. Vegetation was sampled using a block and cluster sampling design, registering tree, shrub, forb and grass species frequency, and the standing aerial biomass of the herbaceous layer in a sampling unit=1 ha. Environmental data (topographic position, fire frequency, current and past use, and tree and shrub cover) were also registered for each sampling unit. Indirect ordination of sampling units classified according to range units and range sites, and correlation with environmental variables were performed using multidimensional scaling (MDS) as well as the vector fitting technique. Standing forage and stocking rate were estimated from biomass data. Results indicate that 'range site' is the ecosystem unit that should be considered for management purposes since it correlates well with plant communities: tall, hardwood forests are located on upland sites, woodlands are located on midland sites and savannas are located on lowland sites. Dense shrub thickets dominate in areas rated in poor condition, irrespective of range site. Disturbances such as fire and current and past use have a significant positive and negative correlation with range condition, respectively, suggesting that a state and transition model would explain vegetation dynamics better than the succession model. The estimated stocking rate in lowland sites in good condition was 2 ha UG(-1), while in upland sites in poor condition the stocking rate was 90 ha UG(-1). Active (fire, mechanical treatments) rather than passive (grazing management) methods should be used for range improvement in order to achieve the full potential of the ecosystem.

Agriculture↗

PubMed2003

pH-dependent amyloid and protofibril formation by the ABri peptide of familial British dementia.

The ABri is a 34 residue peptide that is the major component of amyloid deposits in familial British dementia. In the amyloid deposits, the ABri peptide adopts aggregated beta-pleated sheet structures, similar to those formed by the Abeta peptide of Alzheimer's disease and other amyloid forming proteins. As a first step toward elucidating the molecular mechanisms of the beta-amyloidosis, we explored the ability of the environmental variables (pH and peptide concentration) to promote beta-sheet fibril structures for synthetic ABri peptides. The secondary structures and fibril morphology were characterized in parallel using circular dichroism, atomic force microscopy, negative stain electron microscopy, Congo red, and thioflavin-T fluorescence spectroscopic techniques. As seen with other amyloid proteins, the ABri fibrils had characteristic binding with Congo red and thioflavin-T, and the relative amounts of beta-sheet and amyloid fibril-like structures are influenced strongly by pH. In the acidic pH range 3.1-4.3, the ABri peptide adopts almost exclusively random structure and a predominantly monomeric aggregation state, on the basis of analytical ultracentrifugation measurements. At neutral pH, 7.1-7.3, the ABri peptide had limited solubility and produced spherical and amorphous aggregates with predominantly beta-sheet secondary structure, whereas at slightly acidic pH, 4.9, spherical aggregates, intermediate-sized protofibrils, and larger-sized mature amyloid fibrils were detected by atomic force microscopy. With aging at pH 4.9, the protofibrils underwent further association and eventually formed mature fibrils. The presence of small amounts of aggregated peptide material or seeds encourage fibril formation at neutral pH, suggesting that generation of such seeds in vivo could promote amyloid formation. At slightly basic pH, 9.0, scrambling of the Cys5-Cys22 disulfide bond occurred, which could lead to the formation of covalently linked aggregates. The presence of the protofibrils and the enhanced aggregation at slightly acidic pH is consistent with the behavior of other amyloid-forming proteins, which supports the premise that a common mechanism may be involved in protein misfolding and beta-amyloidosis.

Adaptor Proteins, Signal Transducing↗

PubMed2006

A systematic review of college student-athlete drinking: Prevalence rates, sport-related factors, and interventions.

Alcohol use among college students has become a considerable public health problem. Among this group, intercollegiate athletes are at a particularly high risk for excessive alcohol consumption and resulting negative alcohol-related consequences. The purpose of our review was to systematically examine three main issues related to alcohol consumption among intercollegiate athletes: (a) the prevalence rates and alcohol consumption patterns of this group, especially in comparison with those of collegiate nonathletes; (b) the various factors that might motivate or encourage alcohol use among intercollegiate athletes, primarily sport-related individual and environmental variables; and (c) considerations for conducting alcohol-related interventions with intercollegiate athletes.

Alcohol Drinking↗

PubMed2005

Exploring the genetics of longevity in the Old Order Amish.

Lifespan is a complex phenotype determined by the interaction of genetic and environmental factors. This makes the identification of variants in genes that influence longevity challenging. We believe that the Old Order Amish (OOA) of Lancaster, Pennsylvania is an excellent population for studying the genetics of longevity. They are a closed population derived from a limited number of founders. They have large families and maintain extensive genealogic records dating to the 1700 s. They eschew modern technology; their lifestyle is little changed over the last 250 years. Homogeneity of environment and lifestyle factors across time and across the OOA population minimizes the influence that environmental factors have in determining the differences in lifespan between individuals. We hypothesize that this reduction in environmental variability will make it easier to identify the genetic factors that influence lifespan. In this article, we describe our strategy for identifying variants in genes that influence longevity in the Amish and present the results of our studies to date.

Adult↗

PubMed2004

Effect of biodeposits from mussel culture on macroinvertebrate assemblages at sites of different hydrodynamic regime.

The present study examined for differences in macroinvertebrate assemblage composition inside and outside of mussel farm sites experiencing different hydrodynamic regimes. Multivariate analysis revealed that there were significant differences in macroinvertebrate assemblage composition (averaged across seasons) between samples taken inside and outside of the two relatively low energy sites, whilst no such difference was observed for the relatively high energy site. Taxa that best discriminated between the dissimilarities observed in macroinvertebrate assemblage composition inside and outside farms were principally polychaetes (more abundant inside) and ophiuroids (more abundant outside). Sediment total organic matter and number of mussel shells were the parameters that best explained the difference in macroinvertebrate assemblage observed at the two relatively sheltered farm study sites. No taxa or environmental variables were particularly good at discriminating or explaining differences observed inside and outside the relatively high energy farm site. The present study indicates there is a relationship between the hydrodynamic regime of a farm site, organic enrichment of seabed sediments by mussel biodeposits, and a subsequent modification of the macroinverebrate assemblages. This finding has implications for the site selection of mussel farms in coastal environments.

Animals↗

PubMed2006

Modeling the brain-pituitary-gonad axis in salmon.

To better understand the complexity of the brain-pituitary-gonad axis (BPG) in fish, we developed a biologically based pharmacodynamic model capable of accurately predicting the normal functioning of the BPG axis in salmon. This first-generation model consisted of a set of 13 equations whose formulation was guided by published values for plasma concentrations of pituitary- (FSH, LH) and ovary- (estradiol, 17alpha,20beta-dihydroxy-4-pregnene-3-one) derived hormones measured in Coho salmon over an annual spawning period. In addition, the model incorporated pertinent features of previously published mammalian models and indirect response pharmacodynamic models. Model-based equations include a description of gonadotropin releasing hormone (GnRH) synthesis and release from the hypothalamus, which is controlled by environmental variables such as photoperiod and water temperature. GnRH stimulated the biosynthesis of mRNA for FSH and LH, which were also influenced by estradiol concentration in plasma. The level of estradiol in the plasma was regulated by the oocytes, which moved along a maturation progression. Estradiol was synthesized at a basal rate and as oocytes matured, stimulation of its biosynthesis occurred. The BPG model can be integrated with toxico-genomic, -proteomic data, allowing linkage between molecular based biomarkers and reproduction in fish.

Animals↗