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PubMed1999

Gene by environment interaction and asthma.

The term interaction has two specific meanings in epidemiology. The first definition is purely a statistical one. Interaction is defined as the coefficient of the product term of two or more risk factors. An alternative definition is a more biologically oriented one in which interaction between two risk factors is defined as their coparticipation in the same causal mechanism of disease development. There are at least five different types of biological gene by environment interaction. It is important to recognize that clinical or epidemiological studies alone are unable to distinguish between these five different types of biological interaction. Asthma is a prototypical complex trait in which gene by environment interaction is important in disease causation. Environmental factors important in asthma include cigarette smoking (active/passive), allergen exposure, viral and bacterial respiratory illness, occupation, and possibly diet. There are two primary study designs that have been utilized for the assessment of gene by environment interaction: a traditional case control study or a nested case control study or a case control study nested within the larger longitudinal cohort. There are three important methodological issues in the assessment of gene by environment interaction. The first is the issue of misspecification of either genotype or environmental exposure or, for that matter, disease status. The second is possible confounding, and the third is the confounding of interaction with dose response. The four most critical factors for determining sample size for gene by environment interaction studies are the odds ratio for the interaction, the prevalence for exposure in the population, the prevalence of the genotype in the population, and the case to control ratio. In general, sample sizes have been too small to detect meaningful gene by environment interactions.

Animals↗

PubMed1999

Mechanisms of Ca2+ store depletion in single endothelial cells in a Ca(2+)-free environment.

Depletion of agonist-sensitive Ca2+ stores results in activation of capacitative Ca2+ entry (CCE) in endothelial cells. The proportion of Ca2+ stores contributing to the regulation of CCE is unknown. In fura-2/am loaded single endothelial cells freshly isolated from bovine left circumflex coronary arteries, we investigated whether a resting period in a Ca(2+)-free environment results in emptying of bradykinin-sensitive Ca2+ stores (BsS) and activation of CCE. In a Ca(2+)-free environment, depletion of BsS occurred in a time-dependent manner (59% after 10 min in Ca(2+)-free solution). This effect was prevented by inhibition of the Na(+)-Ca2+ exchange but not by a blockade of ryanodine-sensitive Ca2+ release (RsCR). In contrast to BsS, mitochondrial Ca2+ content remained unchanged in the Ca(2+)-free environment. Remarkably, activity of CCE (monitored as Mn2+ influx) did not increase after depletion of BsS in the Ca(2+)-free environment. In contrast to Mn2+ influx, the effect of re-addition of Ca2+ to elevate bulk Ca2+ concentration ([Ca2+]b) decreased with the time the cells rested in Ca(2+)-free buffer. This decrease was prevented by an inhibition of RsCR. In low Na+ conditions the effect of Ca2+ on [Ca2+]b was reduced while it did not change the time the cells rested in Ca(2+)-free solution. After a 2 min period in low Na+ conditions, ryanodine-induced Ca2+ extrusion was markedly diminished. Inhibition of RsCR re-established the effect of Ca2+ on [Ca2+]b in low Na+ conditions. Collapsing subplasmalemmal Ca2+ stores with nocodazole, increased the effect of Ca2+ on [Ca2+]b. In nocodazole-treated cells, the effect of Ca2+ on [Ca2+]b was not reduced in Ca(2+)-free environment. These data indicate that activation of CCE is not associated with the agonist-sensitive Ca2+ pools that deplete rapidly in a Ca(2+)-free environment. Subplasmalemmal ryanodine-sensitive Ca2+ stores (RsS) are emptied in Ca(2+)-free/low Na+ solution and re-sequester Ca2+ which enters the cells prior an increase in [Ca2+]b occurs. Thus, in endothelial cells there are differences in the functions of various subplasmalemmal Ca2+ stores (i.e. BsS and RsS), which include either activation of CCE or regulation of subplasmalemmal Ca2+.

Animals↗

PubMed2004

Regulating environments to reduce obesity.

The marked increase in the prevalence of obesity appears to be attributable to environmental conditions that implicitly discourage physical activity while explicitly encouraging the consumption of greater quantities of energy-dense, low-nutrient foods. In the United States food environment, consumers are bombarded with advertising for unhealthy food, and receive inadequate nutritional information, especially at restaurants. In the US school environment children have access to sugary sodas and unhealthy a la carte foods in their cafeterias, at the same time getting inadequate physical activity and nutrition education. In the built environment, sprawl has reduced active living. We describe these environments and explore the potential effects of regulatory measures on these environments. In the United States, regulatory opportunities exist at the national, state and local levels to mandate action and to allocate funds for promising health-promoting strategies. Regulatory approaches, much like litigation, can transform the entire environment in which corporations operate. Even with incomplete enforcement of rules, they send a public message about what is acceptable behavior for corporations and individuals. Additionally, because the United States is party to many multilateral and bilateral trade agreements and is an active participant in the GATT/WTO framework, US regulatory actions promise to have a beneficial impact both domestically and globally.

Adolescent↗

PubMed2004

A review of effects and control methods of particulate matter in animal indoor environments.

This paper reviews the effects and control methods for particulate matter (PM) in animal indoor environments. PM in animal indoor environments represents a particular threat to the health of countless animals and millions of workers around the world. Because air in animal facilities has a higher portion of biological content than does air in other environments, the adverse health impact is much greater than it is for the same amount of PM in other environments. Source control, ventilation, and internal air cleaning can reduce PM concentration in animal indoor environments. Source control is typically the most economical method for PM control. Ventilation is the most widely applied technology, although uncertainties remain as to its effectiveness for PM control. Most internal air cleaners require frequent maintenance because of the high concentration and stickiness of PM in animal environments. Filtration is the most well-studied and widely used technology for internal air cleaning because of its low capital cost and high efficiency. Several trials using electrostatic precipitators have shown efficiencies of approximately 50% in removing PM concentration, but improvements are needed before they can be used widely. No report using wet collectors or centrifugals as internal air cleaners has been found.

Air Pollution, Indoor↗

PubMedDate not supplied

The impact of work environment, utility, and sampling design on occupational magnetic field exposure summaries.

Most recent epidemiologic studies investigating the potential health effects of occupational magnetic field (MF) exposure have relied on MF measurement data linked to job titles. These measurements are summarized by occupational categories, which represent similar groups of job titles. However, job titles alone explain only a small proportion of exposure variability. A comprehensive MF occupational exposure database was used to (1) develop summary job-specific estimates of magnetic field exposure, (2) evaluate the impact of incorporating work environment data to improve electric and magnetic field exposure assessment, and (3) evaluate the use of random versus nonrandom sampling when estimating mean MF exposure levels by occupational categories. Uniform classification systems were developed for occupational and work environment data. A factorial design was used to summarize and calculate arithmetic means and 95% confidence intervals for occupational MF data, assuming that the total variation in MF exposure resulted from variation in occupation, work environment, utility, worker, and day. Occupation-specific means varied across different work environments, particularly for craft workers. Although within-worker and between-worker variability account for a large proportion (over 50%) of exposure variation, work environment (24%) accounted for more exposure variability than occupation (4.9%) or utility (15%). Some differences were observed when results were compared from surveys that used random and nonrandom sampling; however, these differences were not consistent or systematic. It was concluded that MF exposure assessment should consider work environment in addition to job title to reduce exposure misclassification.

Data Collection↗

PubMed1997

Comparison of a military chemical suit and an industrial usage vapor barrier suit across two thermal environments.

This study compared physiological responses to wearing military chemical protective clothing (MPC) and industrial vapor barrier protective clothing (IPC) across two thermal environments to determine the application of the MPC research toward IPC use. Ten males wore each ensemble in a wet bulb globe temperature (WBGT) = 18 and 26 degrees C environment for four test sessions. Each test session consisted of two 30-min work bouts separated by a 30-min recovery period. Each work bout consisted of walking on a treadmill with an oxygen demand of 1.4 L/min for 15 min followed by 7 min of arm curling of 0.9 L/min, followed by 8 min of walking. Work was stopped when either the 30-min time limit was met or a core temperature (Tre) of 38 degrees C was achieved. Variables included sweat rate, heart rate at the end of each work bout, change in (delta) Tre and mean skin temperature (mTsk), and heat stored (Whr). A repeated measures analysis of variance showed no significant difference (p > 0.05) between heart rates at the end of the work bouts between the MPC and IPC. A significant difference was found (p < 0.05) between sweat rates (MPC = 11.5, IPC = 7.4 g/min), delta mTsk, and heat stored, all independent of WBGT. A significant difference (p < 0.05) was also found between delta Tre (MPC = 0.52, IPC = 0.90) in the WBGT = 26 degrees C environment. Results indicate that these two suits elicit similar physiological responses in a cool environment (WBGT = 1 degrees C) but different Tre responses in a hot (WBGT = 26 degrees C) environment. Results show that MPC research can be applied toward IPC settings; however, comparisons between the two should be made with caution, particularly in regard to hot environments.

Adult↗

PubMed1962

The influence of environment on the shell structure of starch granules.

It is well known from light microscope studies of potato starch that the granules formed in a constant environment (of light and temperature) have a ring formation indistinguishable from that of granules formed under field conditions. Electron microscope studies have confirmed that normal potato starch granules have a fine shell structure not usually resolved by the light microscope, and also that shells do not develop in barley granules grown in a constant environment. The paper presented here reports a further study of the dependence of shell formation on environment. Potatoes were grown in a constant environment and starch granules from the newly formed tubers were examined in the light microscope, and in the electron microscope after corrosion by acid. No difference between these granules and normal granules was observed; both wide (light microscope) rings and fine lamellae developed in both granules. Parallel studies were made on wheat starch granules. In this case, shells were not differentiated in granules that developed in a constant environment, but they could be produced at will by imposing a dark period. Thus, shell formation in potato granules must be controlled by an endogenous rhythm, whereas in wheat granules it must be controlled by external environment.

Electrons↗

PubMed1989

Effects of physiological oxygen environment on drug-induced cell lethality of multicellular tumor spheroids from human lung cancer.

Advanced malignant tumors of certain histological types contain a hypoxic and necrotic core. Multicellular tumor spheroids (MTS) have the characteristics of chronically hypoxic cells in the center. We studied the effects of physiological oxygen environment on MTS growth and the cell lethality produced by doxorubicin (DXR) and cisplatin (DDP). MTS were made from 2 human lung cancer cell lines; PC-6 small cell and PC-10 squamous cell carcinoma, and grown for 2, 3 or 4 weeks; either in 5% CO2/air or 5% 02/5% CO2/90% N2. They were exposed to graded concentrations of DXR for 1 hr and cell lethality was determined by clonogenic assay. In the physiological oxygen environment MTS growth was retarded for both cell lines. PC-6 MTS grown in physiological oxygen environment were more sensitive to DXR than those developed in air. The differential sensitivity was most pronounced with the 2 week old MTS and gradually narrowed with increasing MTS size. In contrast, PC-10 MTS developed in the physiological oxygen environment were more resistant to DXR than those in air; the differences were again most pronounced in 2 week old MTS. There were little differences in cell kill effects of DDP, irrespective of cells being in monolayer or in MTS and growing in air or in physiological oxygen environment. These observations are consistent with the interpretation that cells in PC-6 MTS are scarcely affected by the physiological oxygen environment but easily affected by DXR, whereas cells in PC-10 MTS responded vice versa.

Antineoplastic Agents↗

PubMed2004

Resistance in the environment.

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Anti-Bacterial Agents↗

PubMed1998

Use of propensities of amino acids to the local structural environments to understand effect of substitution mutations on protein stability.

Advances in site-directed mutagenesis and other genetic engineering techniques have made it possible to create novel proteins of interest. A challenging aspect of these studies is to understand the effect of substitution mutations on folding and stability of natural proteins. We present an analysis of protein structure data, available from the literature, for which substitution mutations have been made and changes in stability characteristics are reported. Amino acid structural environment parameters have been computed for a set of 304 non-homologous best resolved protein structures. The structural environment parameters were used to calculate each of the 20 amino acid propensities to a given structural environment. The observed increase or decrease in stability upon mutation was found to be correlated with the average residue structural environment propensity of wild-type residue versus mutant residue. The analysis presented here helps identification of less optimally placed residues in a given protein structure, and suggests possible substitution mutations to a residue with higher propensity to the corresponding local structural environment. We propose that such substitution mutations, suggested based on amino acid propensities to local structural environments, should bestow higher stability to the protein structure.

Amino Acid Substitution↗

PubMedDate not supplied

The magnet process and the perceived work environment of nurses.

BACKGROUND: Several studies have described the work environment of nurses from magnet and nonmagnet hospitals, but there have been no studies of nurses from hospitals in the magnet application process. OBJECTIVES: To compare the differences between characteristics of hospitals and nurses from three hospital types: magnet hospitals, hospitals in the process of applying for magnet certification, and nonmagnet hospitals, and how nurses from these hospitals perceive their work environment. METHODS: In a national, cross-sectional survey of critical care nurses, the Perceived Nursing Work Environment (PNWE) instrument was administered to measure nurses' perceptions of their work environment. RESULTS: Data were available from 2,092 nurse surveys. Over a third of the respondents were from in-process hospitals and almost half were from nonmagnet hospitals. The majority of nurses were female and from large hospitals in the Atlantic region. The mean age of nurses was 39.5 years and the mean years of work experience in the intensive care unit (ICU) was 10.2 years. Higher nurse scores were significantly associated with magnet certification on one subscale of the PNWE, nursing competence. DISCUSSION: Nurses from magnet hospitals had a positive perception of nursing competence in their work environment. Further research is necessary to examine the nurse work environment and to determine if the characteristics of magnet hospitals have changed.

Adult↗

PubMed2005

Nurses' perceptions of the working environment: a UK independent sector study.

The working environment is an important determinant of employee well-being. Previous UK studies report registered nurses' perception of the working environment using the Work Environment Scale (WES), but surprisingly few include data for nurses working in mental health or learning disability settings. One hundred and sixty-one (58.8%) registered nurses working day shifts in five specialist divisions (forensic adult mental health, adolescent mental health, elderly continuing care, adult and adolescent learning disability and brain injury rehabilitation) of a large charitable hospital comprising mostly secure (i.e. 'locked') wards completed the WES. Nurses working in separate clinical divisions differed only on the 'physical comfort' subscale. These results are discussed in the context of previous UK research: this sample of nurses scored differently on a number of subscales, with the working environment characterized by relatively high levels of support, cohesion and managerial control and slightly lower levels of autonomy. It is unclear whether the differences reflect the organizational (i.e. non-NHS) context, or a secure environment effect. Previous studies of mental health nurses are now 10 years old and we present data that may provide a benchmark of perceptions of the working environment held by nurses working in mental health and learning disability settings.

Adult↗

PubMed2006

Mixed biodiversity benefits of agri-environment schemes in five European countries.

Agri-environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non-ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri-environment schemes and use it to evaluate the biodiversity effects of agri-environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri-environment scheme, the other conventionally managed. In all countries, agri-environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri-environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures.

Agriculture↗

PubMed2006

Not the same everywhere. Patient-centered learning environments at nine medical schools.

BACKGROUND: Learning environments overtly or implicitly address patient-centered values and have been the focus of research for more than 40 years, often in studies about the "hidden curriculum." However, many of these studies occurred at single medical schools and used time-intensive ethnographic methods. This field of inquiry lacks survey methods and information about how learning environments differ across medical schools. OBJECTIVE: To examine patient-centered characteristics of learning environments at 9 U.S. medical schools. DESIGN: Cross-sectional internet-based survey. PARTICIPANTS: Eight-hundred and twenty-three third- and fourth-year medical students in the classes of 2002 and 2003. MEASUREMENTS: We measured the patient-centeredness of learning environments with the Communication, Curriculum, and Culture (C3) Instrument, a 29-item validated measure that characterizes the degree to which a medical school's environment fosters patient-centered care. The C3 Instrument contains 3 content areas (role modeling, students' experiences, and support for students' patient-centered behaviors), and is designed to measure these areas independent of respondents' attitudes about patient-centered care. We also collected demographic and attitudinal information from respondents. RESULTS: The variability of C3 scores across schools in each of the 3 content areas of the instrument was striking and statistically significant (P values ranged from .001 to .004). In addition, the patterns of scores on the 3 content areas differed from school to school. CONCLUSIONS: The 9 schools demonstrated unique and different learning environments both in terms of magnitude and patterns of characteristics. Further multiinstitutional study of hidden curricula is needed to further establish the degree of variability that exists, and to assist educators in making informed choices about how to intervene at their own schools.

Adult↗

PubMed2006

Mercury (micro)biogeochemistry in polar environments.

The contamination of polar regions with mercury that is transported as inorganic mercury from lower latitudes has resulted in the accumulation of methylmercury in the food chain of polar environments, risking the health of humans and wildlife. This problem is likely to be particularly severe in coastal marine environments where active cycling occurs. Little is currently known about how mercury is methylated in polar environments. Relating observations on mercury deposition and transport through polar regions to knowledge of the microbiology of cold environments and considering the principles of mercury transformations as have been elucidated in temperate aquatic environments, we propose that in polar regions (1) variable pathways for mercury methylation may exist, (2) mercury bioavailability to microbial transformations may be enhanced, and (3) microbial niches within sea ice are sites where active microorganisms are localized in proximity to high concentrations of mercury. Thus, microbial transformations, and consequently mercury biogeochemistry, in the Arctic and Antarctic are both unique and common to these processes in lower latitudes, and understanding their dynamics is needed for the management of mercury-contaminated polar environments.

Antarctic Regions↗

PubMed2004

Surface dust contamination and perceived indoor environment in office buildings.

UNLABELLED: The purpose of the study was to evaluate the impact of cleaning on indoor environment quality. Surface dust contamination and occupants' perception of the work environment factors and symptoms were the parameters studied. Six multi-floor office buildings were selected. Dust contamination on surfaces was sampled with gelatine foils and quantified using a BM-Dustdetector. Occupants' perceptions of the environment were assessed with modified MM-40 questionnaires. The results indicated that each building had its own surface dust contamination profile. Weekly cleaning maintained the surface dust contamination at the highest acceptable level for indoor environments. The occupants and their activities have a major effect on the level of dust particle contamination on desks. The correlation between the perceived surface dust contamination and the level of satisfaction with cleaning was as expected. Furthermore, surface dust contamination appeared not to be associated with work-related symptoms. PRACTICAL IMPLICATIONS: The results provide information about current program for contractors and clients, e.g. appropriate cleaning intervals of different surfaces, and the influence of disorder on result. After the evaluation of surface dust contamination levels, it will be possible for cleaning companies to focus on the most important surfaces to clean in order to enhance the quality of the indoor environment in office buildings. This should lead to future development work, which will require cooperation between contractors, clients, and research scientists. In office environments where high cleanliness is required, objective measurements (with instruments) are needed in addition to subjective measurements (the perceptions of occupants). It is essential to evaluate the efficiency of cleaning programs regularly with effective and appropriate quality-monitoring methods.

Analysis of Variance↗

PubMed2002

Taking STOX: developing a cross disciplinary methodology for systematic reviews of research on the built environment and the health of the public.

STUDY OBJECTIVE: To develop a cross disciplinary literature search methodology for conducting systematic reviews of all types of research investigating aspects of the built environment and the health of the public. DESIGN: The method was developed following a comprehensive search of literature in the area of housing and injuries, using 30 databases covering many disciplines including medicine, social science, architecture, science, engineering, environment, planning and psychology. The results of the database searches, including the type (or evidence) of research papers identified, were analysed to identify the most productive databases and improve the efficiency of the strategy. The revised strategy for literature searching was then applied to the area of neighbourhoods and mental health, and an analysis of the evidence type of references was carried out. In recognition of the large number and variety of observational studies, an expanded evidence type classification was developed for this purpose. MAIN RESULTS: From an analysis of 722 citations obtained by a housing and injuries search, an overlap of only 9% was found between medical and social science databases and only 1% between medical and built environment databases. A preliminary evidence type classification of those citations that could be assessed (from information in the abstracts and titles) suggested that the majority of intervention studies on housing and injuries are likely to be found in the medical and social science databases. A number of relevant observational studies (10% of all research studies) would have been missed, however, by excluding built environment and grey literature databases. In an area lacking in interventional research (housing/neighbourhoods and mental health) as many as 25% of all research studies would have been missed by ignoring the built environment and grey literature. CONCLUSIONS: When planning a systematic review of all types of evidence in a topic relating to the built environment and the health of the public, a range of bibliographical databases from various disciplines should be considered.

Databases, Bibliographic↗

PubMed2004

Psychosocial work environment and indoor air problems: a questionnaire as a means of problem diagnosis.

AIMS: To examine the relation between the psychosocial work environment and the perceived indoor air problems measured by a questionnaire survey; and to discuss the role of a questionnaire as a means to enhance collaboration in the challenging multiprofessional process of solving indoor air problems. METHODS: The research material comprises surveys conducted in 1996-99 in 122 office workplaces with 11 154 employees. RESULTS: The association between the psychosocial work environment measured by the Indoor Air Questionnaire (MM-40) and the occupants' complaints concerning indoor air as well as symptoms attributed to indoor air was significant. Those who perceived their psychosocial work environment more negatively had more complaints regarding the indoor environment and more symptoms attributed to the indoor air. The association was detected among both genders, in every age group, among smokers and non-smokers, and respondents with an allergic or a non-allergic background. CONCLUSIONS: Results support the hypothesis that psychosocial factors in the work environment play a significant role in indoor air problems at workplaces. The survey data can be used as a reference database for future studies, and in occupational health care practice when the working conditions of individual workplaces are estimated. The MM-40 could be useful as a practical screening method in field work for analysing the role of the psychosocial work environment among the different background factors of an indoor air problem. However, in order to interpret and evaluate the significance of the results concerning a single workplace, more information on the organisation is needed, as well as cooperation and discussions with the staff. Further studies of the reliability and validity of the psychosocial questions in MM-40 are also needed.

Adolescent↗