Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “environmental variability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed1999

Factors associated with victimization of personnel in emergency departments.

OBJECTIVE: The purpose of this study was to identify the incidence of ED personnel victimization in Central Florida and examine its relationship to victims' reports of 3 factors: characteristics of the patient/perpetrator, characteristics of the personnel victimized, and characteristics of the ED environment. METHODS: Data were collected anonymously in a mail survey using 37 items from Mahoney's Emergency Department Victimization Questionnaire (EDVQ) and a demographic questionnaire. Chi square, Spearman's rank correlation coefficient, and Pearson's product moment correlation were used to describe frequencies, incidence, and their relationships to the variables studied. A sample of 226 of the 600 direct care personnel (37%) from 18 of the 19 hospital emergency departments in a tri-county area (95%) participated. RESULTS: The incidence of physical assault was reported to be 42% during the past year and 72% during the respondents' careers. Alcohol use was associated with incidence (1-tailed Pearson; P =.001). Verbal abuse was significantly higher on day shift (P =.043). The most desired environmental variable was 24-hour security attendants, available to 51.8% of the respondents. More than a fourth of the subjects reported that they had completed no coursework or had no continuing education in violence prevention. DISCUSSION: Respondents reported avoiding identification on duty, underreporting, postvictimization staff turnover, dissatisfaction with security, and the desire for every security provision listed. The goals of reducing the fears and victimization of ED personnel should become a priority within the health care system.

Adult↗
PubMedDate not supplied

An exploratory study of community pharmacy practice change.

OBJECTIVES: (1) To compare the resources and practitioner activities in community pharmacies that have changed practice with those in pharmacies that have not changed; and (2) in pharmacies that have changed practice, to identify factors affecting a pharmacy's ability to support pharmacy practice change. DESIGN: Multiple-case design, in which six pharmacies were studied in depth. SETTING: Six independent community pharmacies in Iowa. PARTICIPANTS: Pharmacy owners. INTERVENTION: A mail survey and an on-site personal interview were used to collect information about the pharmacy's practice changes and influences on the practice change process. MAIN OUTCOME MEASURES: 14 criteria of pharmacy practice change and 5 types of influences on change (environmental variables, organizational variables, owner/manager characteristics, strategy-making features, attributes of change). RESULTS: Three pharmacies had made considerable change, one had made some change, and two had made little or no change. After a broad set of initial changes, subsequent changes tended to be made incrementally. A variety of factors were identified that support pharmacy practice change. Most of the factors were associated with improving resources, such as upgraded staff skills, involvement in demonstration projects, regular environmental scanning, and regular interaction with advocates for pharmacy practice change (e.g., college of pharmacy, pharmacy associations, innovative practitioners). Also, experienced owners who looked to the future and actively addressed constraints were associated with making pharmacy practice change. CONCLUSION: Practitioners and other interested parties should consider a broad array of activities when trying to facilitate pharmacy practice change. Researchers can use these findings to develop studies that will provide stronger scientific evidence that can contribute to a model of pharmacy practice change. The continued study of pharmacy practice change can assist pharmacists working to translate a philosophy of pharmaceutical care into daily practice.

Community Pharmacy Services↗
PubMed2002

Genetic and environmental influences on lipids, lipoproteins, and apolipoproteins: effects of menopause.

OBJECTIVE: Levels of lipids and (apo)lipoproteins are known to increase after menopause, but it is unknown whether the genetic and environmental variability alters or whether lipids and (apo)lipoproteins are influenced by different genes before and after menopause. METHODS AND RESULTS: We studied 453 monozygotic and 1280 dizygotic pairs of female white twins recruited from the St. Thomas' UK Adult Twin Registry and measured total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides, lipoprotein(a) [Lp(a)], apolipoprotein A1 (apoA1), and apolipoprotein B (apoB). Variance components software was used to estimate genetic and environmental influences on serum lipid levels in premenopausal and postmenopausal women. Total variance was higher for triglycerides, HDL, and apoB after menopause. Postmenopausal women showed larger genetic variance for most lipids, apart from apoB and Lp(a). In premenopausal females, total cholesterol, LDL, HDL, apoA1, and apoB all showed an influence of the shared environment (22% to 34%), which, after menopause, decreased in HDL and completely disappeared in total cholesterol, LDL, and apoA1. Only for Lp(a), with a high heritability of 87%, did the same model fit premenopausal and postmenopausal women. Generally, there was no indication that different genes influence lipids before and after menopause. CONCLUSIONS: These findings imply that genetic studies of lipids can pool results from premenopausal and postmenopausal women and that family-based interventions, such as changes in diet, are more likely to succeed in younger women, in whom the environmental influences are greater.

Adolescent↗
PubMed2006

A common haplotype of the dopamine transporter gene associated with attention-deficit/hyperactivity disorder and interacting with maternal use of alcohol during pregnancy.

CONTEXT: Attention-deficit/hyperactivity disorder (ADHD) is a common heritable childhood behavioral disorder. Identifying risk factors for ADHD may lead to improved intervention and prevention. The dopamine transporter gene (DAT1) is associated with ADHD in several studies, with an average 1.2 odds ratio and evidence of heterogeneity across data sets. OBJECTIVE: To investigate sources of heterogeneity by refining the DAT1 association using additional markers and investigating gene-environment interaction between DAT1 and maternal use of alcohol and tobacco during pregnancy. DESIGN: Prospective study. SETTING AND PATIENTS: Children with ADHD from child behavior clinics in the southeast of England and in the Taipei area of Taiwan. INTERVENTIONS: Within-family tests of association using 2 repeat polymorphisms in the 3' untranslated region and intron 8 plus additional markers in the English sample. MAIN OUTCOME MEASURES: Transmission ratios of risk alleles from heterozygote parents to affected offspring and comparison of the transmission ratios in high- and low-exposure groups for the environmental variables. RESULTS: A novel association was identified between ADHD, the intron 8 polymorphism, and a specific risk haplotype in both English and Taiwanese samples. The risk haplotype showed significant interactions with maternal use of alcohol during pregnancy. CONCLUSIONS: The identification of a common haplotype in 2 independent populations is an important step toward identifying functionally significant regions of DAT1. Interaction between DAT1 genotypes and maternal use of alcohol during pregnancy suggests that DAT1 moderates the environmental risk and has implications for the prevention of ADHD. Further studies are required to delineate the precise causal risk factor involved in this interaction.

Alcohol Drinking↗
PubMed2004

3-Methoxytyramine as an indicator of dopaminergic manipulation in the equine athlete.

The influence of sampling variables on the concentration of the dopamine metabolites 3-methoxytyramine (3MT), dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) was examined in equine urine. A logarithmic transformation of the data for all horses gave distribution which approximated the normal distributions for each metabolite. The mean urinary concentration of 3 MT in horses was 214 ng/mL and the application of a threshold with a probability of 1 in 10,000 gave an actionable level of 4 microg/mL. Environmental variables were not forensically significant in determining the population distribution. HVA was not found to be a reliable indicator of dopamine or levodopa administration.

Animals↗
PubMed2002

Selection in the evolution of gene duplications.

BACKGROUND: Gene duplications have a major role in the evolution of new biological functions. Theoretical studies often assume that a duplication per se is selectively neutral and that, following a duplication, one of the gene copies is freed from purifying (stabilizing) selection, which creates the potential for evolution of a new function. RESULTS: In search of systematic evidence of accelerated evolution after duplication, we used data from 26 bacterial, six archaeal, and seven eukaryotic genomes to compare the mode and strength of selection acting on recently duplicated genes (paralogs) and on similarly diverged, unduplicated orthologous genes in different species. We find that the ratio of nonsynonymous to synonymous substitutions (Kn/Ks) in most paralogous pairs is <<1 and that paralogs typically evolve at similar rates, without significant asymmetry, indicating that both paralogs produced by a duplication are subject to purifying selection. This selection is, however, substantially weaker than the purifying selection affecting unduplicated orthologs that have diverged to the same extent as the analyzed paralogs. Most of the recently duplicated genes appear to be involved in various forms of environmental response; in particular, many of them encode membrane and secreted proteins. CONCLUSIONS: The results of this analysis indicate that recently duplicated paralogs evolve faster than orthologs with the same level of divergence and similar functions, but apparently do not experience a phase of neutral evolution. We hypothesize that gene duplications that persist in an evolving lineage are beneficial from the time of their origin, due primarily to a protein dosage effect in response to variable environmental conditions; duplications are likely to give rise to new functions at a later phase of their evolution once a higher level of divergence is reached.

Animals↗
PubMed1992

Field evaluation of coverall fabrics: heat stress and pesticide penetration.

The effect of wearing coveralls on the heat stress of ten professional airblast applicators of ethion to Florida citrus were studied. During the period June 21, 1988 to August 9, 1988, applicators wore protective clothing of the same design, but made of seven different fabrics. Heat stress was evaluated by measuring the mean skin temperature, oral temperature, and heart rate of pesticide applicators. Subjects also provided subjective evaluations. Seven environmental variables were also monitored. Although each fabric was replicated an average of 17 times for thermal comfort and an average of 23 times for penetration, statistical tests for differences among fabrics were usually not significant at the p less than 0.05 level. Observed differences among suits were statistically significant at p = 0.27 for the heat stress experiment, and extended over the range p = 0.003-0.500 for the penetration experiment. Lighter weight, untreated fabrics marginally ameliorated heat stress under severe environmental conditions, but they allowed more pesticide penetration.

Adult↗
PubMed2004

About-weekly variations in nocturia.

The aim of this study was to assess components of variation in nocturia and to determine any putative geomagnetic influence. A 54-year old man with benign prostatic hyperplasia had recorded for about 4 years the number of times he awoke each night to urinate. The data have been reanalyzed for chronomics, the mapping of time structures (chronomes), involving the computation of least squares spectra of the urinary record and of environmental variables recorded during the same 4-year span. In addition to the previously reported monthly variation, other periodicities have been documented, including two separate components with periods of one week and of a near-week. The precise 7-day period may be a mainly exogenous resonance with external influences such as a weekly social schedule, whereas the near-week may be a partial resonance with natural changes in geomagnetics, reflecting in part changes in other non-photic natural environmental factors.

Biological Clocks↗
PubMed2002

Food intake in the real world: implications for nutrition and aging.

Nutrient intakes are affected by two classes of factors, physiological and environmental. In the real world, environmental variables such as social factors, palatability, and the time of eating appear to have large influences on amounts ingested in the short-term. Physiological control mechanisms also operate to regulate intake, and they induce compensatory responses to deviations from the norm. These physiological influences only appear to have weak influences on short-term intake unless there are large deviations from the normal state, but over the long-term they act patiently and persistently to rectify the excesses produced by environmental fluctuations and thereby tend to maintain a relative balance between energy intake and expenditure. As individuals age there is a progressive decline in physiological function including the mechanisms that act to control intake in the young. This should not produce a problem in a healthy individual in a stable environment: however, if that situation should change due to illness or an environmental change such as the death of a spouse, which produces decline in intake, elderly individuals would not have the physiological mechanisms present to compensate. Thus, the deficit in energy intake would not be replaced, and the lower level of intake would be maintained as long as the new health condition or environment remains stable. Hence, the decline in the effectiveness of the physiological systems with age makes the elderly particularly vulnerable and unable to rebound from deficits. Although the elderly have difficulty compensating for deficits automatically by physiologically-induced adjustments, the studies of real world intake reviewed in this article suggest that compensation can be produced by adjustments to the environment. The elderly appear to be as responsive to environmental factors as younger individuals. In particular, they appear to increase intake in response to social facilitation, diurnal rhythms, the eating environment, and palatability to the same extent as their juniors. These data suggest that alterations in the social, temporal, environmental, or hedonic conditions of eating could induce desired alterations in the nutrient intakes of the elderly. The study of real world eating behavior has produced evidence that suggests that this strategy can work. It remains for future applied investigations to ascertain whether or not this strategy is effective in treating undernutrition in the elderly.

Aged↗
PubMed1998

Ahr null alleles: distinctive or different?

Two independent laboratories have generated Ahr "null" or "knockout" mice that share some common characteristics but also have distinct phenotypes. In this Commentary, we will discuss our view of the candidate variables that might account for these differences. More importantly, we hope that this discussion can identify important parameters to be assessed by investigators in the process of characterizing their own modified loci. The variables that we have considered include the possibility that different targeting strategies can result in altered products with unsuspected function or that the targeting event itself can alter the function of neighboring genes. Further, genetic background can have an important influence on phenotype, and differences in genome can be introduced during derivation by the type of embryonic stem cells used and by the random segregation of parental genes in the F2 generation of line propagation. In addition, phenotype may be acutely sensitive to environmental variables, such as pathogen and chemical exposure and stress introduced by crowding and disease. Finally, we discuss approaches to resolving differences between null mice and propose a partial solution, the institution of a repository for detailed information on targeted alleles that may not typically be allowed in today's "fast paced" scientific publications.

Alleles↗
PubMed1985

Dengue transmission in two Puerto Rican communities in 1982.

Paired serologic, entomologic, and environmental surveys were performed in two Puerto Rican communities, Salinas and Manatí, in summer and fall 1982. Paired samples on 434 persons in Salinas and 324 persons in Manatí showed recent dengue infection rates of 35% and 26%, respectively. Ae. aegypti larval indices were higher in Salinas than in Manatí but were relatively high throughout both communities. Breteau indices in neighborhoods ranged from 43 to 172, and infection rates in the neighborhoods were 22% to 45%. With a multivariate technique, we analyzed possible associations of environmental variables with dengue incidence and prevalence of dengue antibody. Wood-constructed housing and low socioeconomic status were among the variables significantly associated with dengue incidence. Predictors of dengue antibody prevalence included socioeconomic level, tree height, shade, and window and door screens. Recent dengue infections clustered within the sampled members of households (P less than 0.05, binomial test). An estimated 35% of dengue infections were symptomatic, and no serious illnesses were reported. The potential for high dengue infection rates in Puerto Rico will continue unless substantial reductions in vector populations are achieved. Targeting dengue surveillance and vector control activities in areas with demonstrated environmental risk factors may limit transmission during future outbreaks.

Adolescent↗
PubMed2005

Relationship between bird abundances and landscape characteristics: the influence of scale.

Scale is important to consider when investigating effects of the environment on a species. Breeding Bird Survey (BBS) data and landscape metrics derived from aerial photographs were evaluated to determine how relationships of bird abundances with landscape variables changed over a continuous range of 16 spatial scales. We analyzed the average number of birds per stop (1985-1994) for five songbird species (family Cardinalidae) for each of 50 stops on 198 BBS transects throughout six states in the Central Plains, USA. Land along each transect was categorized into six cover types, and landscape metrics of fractal dimension (a measure of shape complexity of habitat patches), edge density, patch density, and percent area were calculated, with principal components used to construct composite environmental variables. Associations of bird abundances and landscape variables changed in accordance with small scale changes. Abundances of three species were correlated with edge density and one with component I, which subsumes initial variables of patch density for urban, closed forest, open forest, and open country. Fractal dimension and component II (summarizing amount of closed forest versus open country) were associated with the most species. Correlation patterns of fractal dimension with northern cardinal (Cardinalis cardinalis) and painted bunting (Passerina ciris) abundances were similar, with highest correlations at intermediate to small scales, suggesting indirectly that these species thrive in areas where local habitat conditions are most important. Multiscale analysis can provide insight into the spatial scale(s) at which species respond, a topic of intrinsic scientific interest with applied implications for researchers establishing protocols to assess and monitor avian populations.

Animals↗
PubMed1986

Resource allocation under poor growth conditions. A major role for growth substances in developmental plasticity.

This article argues that the basic function for growth substance is resource allocation under poor growth conditions. The following scheme is suggested. Plants in the wild frequently suffer a paucity of resources which result from interplant competition and ecological and local environmental variation. The strategy adopted by many plants particularly ruderals (from which crops may have evolved) to help mitigate these problems is phenotypic plasticity; the growth of the plant body is adjusted to best exploit the scarce resources and help achieve desirable growth and reproductive goals. Phenotypic plasticity requires decisions to be made concerning the diversion of scarce growth resources to one facet of development rather than another; for example, to height or leaf area rather than thickness; or, between tissues, stem rather than leaves. Growth substances are coupled to these individual facets of development. They represent a simple way in which the extent of resource diversion can be controlled. Cells in specific tissues acquire sensitivity to particular growth substances at a stage in their development when environmental variability often necessitates choices to be made. This acquisition of ontogenetic sensitivity may be all or none. It may reflect acquisition of receptor proteins coupled to specific metabolic events. However in well-nourished plants these phases of development are relatively insensitive to changes in the level of the growth substance/receptor complex. Cells become more sensitive under certain well-defined but specific circumstances, characterized by the general term, poor growth conditions. These are produced by imbalances in one or more of the major environmental (nutritional) requirements for growth, light, nitrogen, water and oxygen. Imbalance in one or more of these produces characteristic and far-reaching metabolic and protein synthesis changes which normally constrain the synthetic processes for growth but amplify metabolic events coupled to growth substances. It is the function of growth substances to circumvent some of these metabolically constraining steps and by applying a constant stimulus to one specific aspect of growth or metabolism permit continued development. The additional input of growth substances into particular facets of development ensures the better maintenance (protection) of that character when competition for resources inside the plant is severe. However competition for scarce resources ensures that continuation of one growth aspect generally leads to relative depletion of others.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗
PubMed1986

Respiratory function of children in homes insulated with urea formaldehyde foam insulation.

A study was carried out to assess the respiratory function of children living in homes insulated with urea formaldehyde foam insulation (UFFI). A large data base on the effect of environmental variables on the respiratory function of 3500 children in the Hamilton, Ont., area had been collected from 1978 to 1980. From this data base 29 children who lived in UFFI-insulated homes were identified, and each was matched with 2 controls according to nine variables that had been shown to be strongly predictive of respiratory function. Reported respiratory symptoms and results of pulmonary function testing in the year immediately following installation of UFFI were examined. No significant differences in any variable were found between the subjects and controls. A power calculation indicated that the study had adequate power to detect clinically important changes. The authors conclude that there was no evidence of respiratory problems resulting from UFFI in the sample studied.

Child↗
PubMed1991

Characteristics of effective clinical teachers of ambulatory care medicine.

This study identified characteristics of clinical teachers in ambulatory care settings that influenced ratings of overall teaching effectiveness and examined the impacts of selected variables of the clinic environment on teaching effectiveness ratings. A survey instrument derived from prior research and observations of ambulatory care teaching was sent to 165 senior medical students and 60 medicine residents at the University of Washington School of Medicine in 1988. A total of 122 (74%) of the seniors and 60 (71%) of the residents responded. Results indicate that the most important characteristics of the ambulatory care teachers were that they actively involved the learners, promoted learner autonomy, and demonstrated patient care skills. Environmental variables did not have a substantial influence on these ratings.

Ambulatory Care↗
PubMed2003

Injuries among disabled children: a study from Greece.

OBJECTIVE: To compare the differential implications of sociodemographic and situational factors on the risk of injury among disabled and non-disabled children. DESIGN: Data from the Emergency Department Injury Surveillance System (EDISS) were used to compare, in a quasi case-control approach, injured children with or without disability with respect to sociodemographic, event and injury variables, and to estimate adjusted odds ratios for the injury in a disabled rather than a non-disabled child. SETTING: Two teaching hospitals in Athens and two district hospitals in the countryside that participate in the EDISS. PATIENTS: In the five year period 1996-2000, 110 066 children were recorded with injuries; 251 among them were identified as having a motor/psychomotor or sensory disability before the injury event. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Mechanism of injury, type of injury, risk-predisposing socioeconomic and environmental variables, odds ratio for injury occurrence. RESULTS: Falls and brain concussion are proportionally more common among disabled children, whereas upper limb and overexertion injuries are less common among them. Urban environment, migrant status, and cold months are also associated with increased odds for injuries to occur among disabled rather than non-disabled children. The odds ratio for the occurrence of an injury among disabled children increases with increasing age. CONCLUSIONS: The results of the study provide the information for the targeting of trials of preventive measure in disabled children at increased risk of severe injuries.

Accidental Falls↗
PubMed2001

Sediment nutrient characteristics and aquatic macrophytes in lowland English rivers.

Aquatic macrophytes play an important role in the nutrient dynamics of streams. As a result, there is much interest in their use as trophic indicators. However, the relationship between aquatic macrophytes and the trophic status of rivers is a complex one, partly because of the effects of a wide range of environmental variables and partly because submerged, rooted macrophytes can absorb nutrients from the river sediments and/or the water column. Experiments which have tried to establish the relative importance of sediments or water as sources of nutrients are inconclusive and further work is needed to establish how sediment nutrient characteristics vary within and among rivers (spatially and temporally) and the inter-relationships between sediment nutrients, water column chemistry and macrophytes. This paper presents the initial findings from a study of 17 lowland rivers in southern England which is exploring the spatial variability of sediment characteristics (total and inorganic phosphorus, total nitrogen, organic carbon, silt-clay fraction and organic matter content) and the relationship with aquatic macrophytes. The preliminary analysis indicates that although sediment characteristics are highly variable within 100-m river reaches, the variability across the 17 rivers is even greater; this is despite the limited geographic and trophic range of the study sites. The results presented in this paper also give some indication of the sediment characteristics associated with five macrophyte species but it is too early to ascribe sediment preferences for particular species.

Environmental Monitoring↗
PubMed1993

Nosocomial Legionnaires' disease: aspiration as a primary mode of disease acquisition.

PURPOSE: Nosocomial Legionnaires' disease remains a significant problem with many unresolved questions regarding transmission of legionella organisms to patients. We performed a case-control and environmental study to identify risk factors and modes of transmission of Legionella infection during an outbreak of nosocomial Legionnaires' disease in a military medical center. PATIENTS AND METHODS: During the calendar year 1989, 14 cases of nosocomial Legionnaires' disease were identified by active surveillance following the discovery of 2 culture-proven cases among organ transplant recipients. Four control patients were matched to each case by age, sex, and date of admission. Cases and controls were compared with respect to past medical history and hospital exposure variables. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for matched variables. Environmental culturing of air and water supplies in and around the medical center was also performed. RESULTS: The case-control study revealed the following significant risk factors for the acquisition of nosocomial Legionnaires' disease: immunosuppressive therapy (OR = 32.7, CI = 4.5 to 302.6), nasogastric tube use (OR = 18.4, CI = 2.6 to 166.2), bedbathing (OR = 10.7, CI = 2.2 to 59.0), and antibiotic therapy (OR = 14.6, CI = 2.9 to 84.4). Shower use (OR = 0.1, CI = 0 to 0.4) appeared to be a negative risk factor. Water cultures revealed Legionella pneumophila serogroup 1, monoclonal antibody subtype Philadelphia (identical to all patient isolates) in the ground-water supply to the hospital, 1 hot-water tank, and 15% of 85 potable water sites tested. Air sampling of cooling towers, hospital air intakes, and medical air and oxygen supplies were negative for Legionella organisms. CONCLUSIONS: This study confirms the importance of potable water in transmitting nosocomial Legionnaires' disease and suggests that the organism gains access to the hospital via external water supplies. The risk factors identified in this case-control study provide evidence that Legionnaires' disease may act as a superinfection in a nosocomial setting and is likely acquired by aspiration, similar to other nosocomial pneumonias.

Adult↗