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PubMed2005

Foodborne pathogens in milk and the dairy farm environment: food safety and public health implications.

Milk and products derived from milk of dairy cows can harbor a variety of microorganisms and can be important sources of foodborne pathogens. The presence of foodborne pathogens in milk is due to direct contact with contaminated sources in the dairy farm environment and to excretion from the udder of an infected animal. Most milk is pasteurized, so why should the dairy industry be concerned about the microbial quality of bulk tank milk? There are several valid reasons, including (1) outbreaks of disease in humans have been traced to the consumption of unpasteurized milk and have also been traced back to pasteurized milk, (2) unpasteurized milk is consumed directly by dairy producers, farm employees, and their families, neighbors, and raw milk advocates, (3) unpasteurized milk is consumed directly by a large segment of the population via consumption of several types of cheeses manufactured from unpasteurized milk, (4) entry of foodborne pathogens via contaminated raw milk into dairy food processing plants can lead to persistence of these pathogens in biofilms, and subsequent contamination of processed milk products and exposure of consumers to pathogenic bacteria, (5) pasteurization may not destroy all foodborne pathogens in milk, and (6) inadequate or faulty pasteurization will not destroy all foodborne pathogens. Furthermore, pathogens such as Listeria monocytogenes can survive and thrive in post-pasteurization processing environments, thus leading to recontamination of dairy products. These pathways pose a risk to the consumer from direct exposure to foodborne pathogens present in unpasteurized dairy products as well as dairy products that become re-contaminated after pasteurization. The purpose of this communication is to review literature published on the prevalence of bacterial foodborne pathogens in milk and in the dairy environment, and to discuss public health and food safety issues associated with foodborne pathogens found in the dairy environment. Information presented supports the model in which the presence of pathogens depends on ingestion of contaminated feed followed by amplification in bovine hosts and fecal dissemination in the farm environment. The final outcome of this cycle is a constantly maintained reservoir of foodborne pathogens that can reach humans by direct contact, ingestion of raw contaminated milk or cheese, or contamination during the processing of milk products. Isolation of bacterial pathogens with similar biotypes from dairy farms and from outbreaks of human disease substantiates this hypothesis.

Animals↗

PubMed1995

A molecular investigation of genotype by environment interactions.

The fitnesses conferred by seven lactose operons, which had been transduced into a common genetic background from natural isolates of Escherichia coli, were determined during competition for growth rate-limiting quantities of galactosyl-glycerol, a naturally occurring galactoside. The fitnesses of these same operons have been previously determined on lactose and three artificial galactosides, lactulose, methyl-galactoside and galactosyl-arabinose. Analysis suggests that although marked genotype by environment interactions occur, changes in the fitness rankings are rare. The relative activities of the beta-galactosidases and the permeases were determined on galactosyl-glycerol, lactose, lactulose and methyl-galactoside. Both enzymes display considerable kinetic variation. The beta-galactosidase alleles provide no evidence for genotype by environment interactions at the level of enzyme activity. The permease alleles display genotype by environment interactions with a few causing changes in activity rankings. The contributions to fitness made by the permeases and the beta-galactosidases were partitioned using metabolic control analysis. Most of the genotype by environment interaction at the level of fitness is generated by changes in the distribution of control among steps in the pathway, particularly at the permease where large control coefficients ensure that its kinetic variation has marked fitness effects. Indeed, changes in activity rankings at the permease account for the few changes in fitness rankings. In contrast, the control coefficients of the beta-galactosidase are sufficiently small that its kinetic variation is in, or close to, the neutral limit. The selection coefficients are larger on the artificial galactosides because the control coefficients of the permease and beta-galactosidase are larger. The flux summation theorem requires that control coefficients associated with other steps in the pathway must be reduced, implying that the selection at these steps will be less intense on the artificial galactosides. This suggests that selection intensities need not be greater in novel environments.

Alleles↗

PubMed1976

Genetic variation in a heterogeneous environment. II. Temporal heterogeneity and directional selection.

The maintenance of genetic variation is investigated in a finite population where selection at an autosomal locus with two alleles varies temporally between two environments and the heterozygote has an intermediate fitness value. When there is additive gene action and equal selection in both environments, the autocorrelation between subsequent environments must be negative for more maintenance of genetic variation than for neutrality. The maximum maintenance occurs when there is equal selection in the two environments and the autocorrelation approaches -1.0 (for a stochastic model), or when there is short repeating cycle such as one related to seasons. Also comparison of the effects of stochastic variation in selection in finite ans infinite populations is made by using Monte Carlo simulation. One situation was found where temporal environmental variation maintains genetic variation very effectively even in a small population and that is when there is evolution of dominance, i.e., the heterozygote is closer in fitness to the favored homozygote than the other homozygote. An important conclusion is that in a finite population genetic tracing of environmental change, particularly when there is a positive autocorrelation between environments or a long environmental cycle, leads to an increased loss of genetic variation making such a response undesirable in the long term, a result different from that in infinite populations.

Gene Frequency↗

PubMed1997

Sample size requirements in case-only designs to detect gene-environment interaction.

With advances in molecular genetic technology, more studies will examine gene-environment interaction in disease etiology. If the primary purpose of the study is to estimate the effect of gene-environment interaction in disease etiology, one can do so without employing controls. The case-only design has been promoted as an efficient and valid method for screening for gene-environment interaction. The authors derive a method for estimating sample size requirements, present sample size estimates, and compare minimum sample size requirements to detect gene-environment interaction in case-only studies with case-control studies. Assuming independence between exposure and genotype in the population, the authors believe that the case-only design is more efficient than a case-control design in detecting gene-environment interaction. They also illustrate a method to estimate sample size when information on marginal effects (relative risk) of exposure and genotype is available from previous studies.

Case-Control Studies↗

PubMed2006

Genotyping of Campylobacter jejuni from broiler carcasses and slaughterhouse environment by amplified fragment length polymorphism.

We examined the occurrence and diversity of Campylobacter jejuni on broiler carcasses during slaughter of an infected flock and in the slaughterhouse environment during slaughter and postdisinfection before a new production run. During the slaughter of a known C. jejuni infected broiler flock, samples were taken from broiler carcasses at 7 different stages during the process. Thirty-seven sites in the slaughterhouse environment were sampled both during process and postdisinfection. The samples were analyzed for C. jejuni, and genetic fingerprinting was performed using amplified fragment length polymorphism. All carcass samples were positive. Of the environmental samples collected during slaughter, 89% were positive; 100% of those from the arrival, stunning, scalding, defeathering, and evisceration facilities and 67% of those from the cooling and sorting facilities. Postdisinfection, 41% of the samples were positive; 71% of those from the arrival and stunning area, 60% of those from the scalding and defeathering area, and 20% of those from the evisceration, cooling, and sorting area. The C. jejuni isolates (n = 60) recovered were grouped into 4 different amplified fragment length polymorphism clones with a similarity index of 95% or greater. All isolates obtained from the flock and 94% of the isolates obtained from the environment during slaughtering belonged to clone A, whereas 1 environmental isolate belonged to each of the clones B and C. Isolates from clones A, B, and D were present postdisinfection. Only clone B was detected on flocks slaughtered during the previous week. The high level and continuous presence of Campylobacter in the environment constitutes a risk for transmission to negative carcasses. In Norway, where above 96% of the broiler flocks are Campylobacter-negative, this aspect is of special importance. The ability of Campylobacter to remain in the slaughterhouse environment through washing and disinfection is associated with constructional conditions of equipment and buildings, complicating cleaning and providing sufficient moisture. To reduce the probability of the workers acquiring campylobacteriosis, precautions should be taken when slaughtering Campylobacter-positive flocks.

Abattoirs↗

PubMed2006

Enriched acoustic environment after noise trauma abolishes neural signs of tinnitus.

Noise-induced hearing loss induces reorganization of the tonotopic map in cat auditory cortex and increases spontaneous firing rate and neural synchrony. We showed previously that keeping cats after noise trauma in an acoustic environment enriched in high frequencies prevents tonotopic map reorganization. Here, we show the effects of low-frequency and high-frequency enriched acoustic environments on spontaneous firing rate and neural synchrony. Exposed cats placed in the quiet environment and in the low-frequency enriched acoustic environment showed increased spontaneous firing rate and synchrony of firing. In contrast, exposed cats placed in the high-frequency enriched acoustic environment did not show significant differences in spontaneous firing rate or synchrony compared with normal hearing controls. This is interpreted as an absence of putative neural signs of tinnitus.

Acoustic Stimulation↗

PubMed1997

A predictive model of student satisfaction with the medical school learning environment.

PURPOSE: To examine differences in attitudes toward the medical school learning environment among student subgroups based on gender and race-ethnicity, to identify the most influential predictors of student satisfaction with the learning environment, and to create a model of student satisfaction with the learning environment. METHOD: Three years of survey data (1992-93 to 1994-95) from first-year students at the University of Michigan Medical School were combined. The total sample consisted of 430 respondents, broken into two sets of subgroups: women (n = 171) and men (n = 259), and whites (n = 239) and underrepresented minorities (n = 74). Asian students were removed from analyses when comparisons were made by race-ethnicity, but were included in the analyses for all students and those comparing men and women. Student's t-tests were used to identify differences between gender and racial-ethnic groups in mean responses to seven survey items, and effect sizes were used to characterize the magnitudes and practical significances of the differences. Forward stepwise regression was conducted to determine the best predictive models for each student subgroup and for the total sample; the subgroup models were compared with each other as well as with the total-sample model. RESULTS: Cross-validation of the gender and race-ethnicity models showed that the men's satisfaction and the women's satisfaction were predicted equally well using either subgroup's model, and that the white students' satisfaction and the underrepresented-minority students' satisfaction were predicted equally well using either subgroup's model. Furthermore, the total-sample model, employing a subset of five predictors, was similar in its predictive power to the subgroup models. CONCLUSION: The study's findings suggest that curriculum structure (timely feedback and the promotion of critical thinking) and students' perceptions of the priority faculty place on students' education are prominent predictors of student satisfaction (across all subgroups) with the learning environment. In contrast, students' perceptions of the learning environment as a comfortable place for all gender and racial-ethnic groups, although less prominent predictors of satisfaction, will discriminate among the subgroups.

Consumer Behavior↗

PubMed2005

Compliance with common program requirements in Brazil: its effects on resident's perceptions about quality of life and the educational environment.

PURPOSE: In 1981, Brazil's National Committee on Medical Residency established the Common Program Requirements (CPRs), to regulate residents' work hours. The authors studied whether program violations of the CPRs regarding residents' duty hours, time for educational activities, and faculty supervision adversely affected residents' perceptions about the quality of their lives and about the educational environment. METHOD: From October through December 2003, 88 residents from four institutions in Florianopolis (SC), Brazil were invited to participate of the study. Residents completed four instruments: a questionnaire about their program's compliance with CPRs; the Dundee Ready Educational Environment Measure (DREEM) that assesses perceptions about the learning environment; the Quality of School Life Scale (QSL), which assesses the quality of life at school; and the WHO Quality of Life Assessment (WHOQOL), which assesses the general quality of life. Residents were categorized according to gender, institution, year of training, specialty, and their answers on the CPRs questionnaire. DREEM, SQL, and WHOQOL scores were compared between categories. RESULTS: A total of 62 residents (70%) responded. A significant number of residents reported their program's noncompliance with CPRs. Residents reporting program compliance rated higher parameters of general quality of life, quality of life in residency, and the educational environment. CONCLUSION: Violations of Brazil's residency program CPRs are associated with residents' worse perceptions of several aspects of general quality of life, quality of life in residency, and the educational environment.

Adult↗

PubMed1993

Tritium transport and cycling in the environment.

The transport and cycling of tritium in the environment can be understood in terms of the role of hydrogen in the environment. Physical and chemical isotopic effects, while present in some transport mechanisms and chemical reactions, are not important factors in environmental tritium dynamics. In addition, because of the role of hydrogen in metabolism and its ubiquitousness in the environment, organisms have not evolved mechanisms to accumulate or concentrate hydrogen or its isotopes in food chains. Therefore, biomagnification of tritium is not a factor in food chain transfer. The lack of significant isotopic effects or biomagnification means that tritium transport and cycling in the environment can be predicted on the basis of the transport processes, hydrogen content, and chemical transformation of hydrogen and its compounds in the environment.

Environmental Exposure↗

PubMed1998

Methodology for determining action levels for clean-up contaminated urban and agricultural environments.

A methodology for determining justified action levels for clean-up of contaminated environments has been elaborated based upon dose reductions and monetary costs associated with the clean-up or remedial measures. Action levels can be expressed as dose or contamination levels above which clean-up is justified and below which it is not. This paper discusses the factors needed to determine such action levels. The most important of these factors are the efficiency of the clean-up and the monetary costs of the clean-up operation. Examples of justified action levels for clean-up of urban and agricultural environments have been determined from uncertainty analyses. With selected parameter distributions for clean-up of urban and semi-urban environments, justified action levels for clean-up are found to be in the range of about 1-10 mSv y(-1). With selected parameter distributions for agricultural countermeasures, action levels for reduction of activity content in milk have been determined to be from less than 100 Bq L(-1) up to a few thousand Bq L(-1), corresponding to residual individual ingestion doses of about 0.1-0.5 mSv y(-1). The presented methodology, which can be extended to include more complex environments, can in a simple way give the decision maker an indication of when it is justified to clean a contaminated environment.

Agriculture↗

PubMed2004

Accessibility and usability of the physical housing environment of seniors with stroke.

This study measured how stroke survivors perceived their housing environment. Quantitative and qualitative data were collected using the Usability in My Home Questionnaire with 19 stroke survivors who all lived in the community. Overall, they reported that the design of their homes allowed them to manage their self-care activities but not all of their household activities. The outside design of the home posed difficulties, with uneven ground and poor lighting and stair access. Inside the home, space was a problem, particularly for stroke survivors using wheelchairs. Living in restricted spaces was the result of the person-technology-environment fit. These results show that the housing environment is not experienced similarly by all old persons, and that the environmental experiences reported by the sample often appear inconsistent with the quality of their housing environment as judged by objective indicators; for instance, subjective reports are often more favorable than would be expected in light of the limiting aspects of the objective environment. Recommendations for housing design strategies and for occupational therapy practice are offered.

Aged↗

PubMedDate not supplied

Testing for EMC (electromagnetic compatibility) in the clinical environment.

Testing for electromagnetic compatibility (EMC) in the clinical environment introduces a host of complex conditions not normally encountered under laboratory conditions. In the clinical environment, various radio-frequency (RF) sources of electromagnetic interference (EMI) may be present throughout the entire spectrum of interest. Isolating and analyzing the impact from the sources of interference to medical devices involves a multidisciplinary approach based on training in, and knowledge of, the following: operation of medical devices and their susceptibility to EMI; RF propagation modalities and interaction theory; spectrum analysis systems and techniques (preferably with signature analysis capabilities) and calibrated antennas; the investigation methodology of suspected EMC problems, and testing protocols and standards. Using combinations of standard test procedures adapted for the clinical environment with personnel that have an understanding of radio-frequency behavior increases the probability of controlling, proactively, EMI in the clinical environment, thus providing for a safe and more effective patient care environment.

Electromagnetic Phenomena↗

PubMed1996

The Practice Environment Project. A process for outcome evaluation.

OBJECTIVE: Evaluating the practice environment is essential to determine if the practice environment is conducive to the delivery of quality patient care. The Practice Environment Project (PEP) was created to provide a framework for current and ongoing evaluation of the practice environment. BACKGROUND: Major changes in the delivery of patient care services have focused attention on the evaluation of the effectiveness of these changes. The extent and type of change may vary throughout an institution. The identification of core variables to assess the effectiveness of these changes sets the framework for ongoing evaluation of new unit-based models for delivery of services. METHODS: In part 1, quantitative data were collected from nursing staff members (job satisfaction, collaboration with physicians, autonomy), physicians (quality of nursing care, collaboration with nurses), and patients (satisfaction with nursing care). In part 2, focus groups were held with nursing personnel to discuss factors that affected the provision of services. Unit-based action plans were developed to manage barriers to the delivery of services. RESULTS: Patients and physicians reported a high degree of satisfaction with patient care. Physicians reported a higher level of collaboration with nurses than that reported by nurses. Nurses reported a high degree of autonomy in practice, however, in other areas of job satisfaction (development and recognition), they suggested areas for improvement. CONCLUSIONS: The PEP created a mechanism to evaluate the current state-of-the-practice environment by identifying core elements for evaluation of work redesign. It also provided a framework for managing barriers that disrupted the delivery of patient care services.

Focus Groups↗

PubMed2003

The genesis of neurosurgery and the evolution of the neurosurgical operative environment: part II--concepts for future development, 2003 and beyond.

The future development of the neurosurgical operative environment is driven principally by concurrent development in science and technology. In the new millennium, these developments are taking on a Jules Verne quality, with the ability to construct and manipulate the human organism and its surroundings at the level of atoms and molecules seemingly at hand. Thus, an examination of currents in technology advancement from the neurosurgical perspective can provide insight into the evolution of the neurosurgical operative environment. In the future, the optimal design solution for the operative environment requirements of specialized neurosurgery may take the form of composites of venues that are currently mutually distinct. Advances in microfabrication technology and laser optical manipulators are expanding the scope and role of robotics, with novel opportunities for bionic integration. Assimilation of biosensor technology into the operative environment promises to provide neurosurgeons of the future with a vastly expanded set of physiological data, which will require concurrent simplification and optimization of analysis and presentation schemes to facilitate practical usefulness. Nanotechnology derivatives are shattering the maximum limits of resolution and magnification allowed by conventional microscopes. Furthermore, quantum computing and molecular electronics promise to greatly enhance computational power, allowing the emerging reality of simulation and virtual neurosurgery for rehearsal and training purposes. Progressive minimalism is evident throughout, leading ultimately to a paradigm shift as the nanoscale is approached. At the interface between the old and new technological paradigms, issues related to integration may dictate the ultimate emergence of the products of the new paradigm. Once initiated, however, history suggests that the process of change will proceed rapidly and dramatically, with the ultimate neurosurgical operative environment of the future being far more complex in functional capacity but strikingly simple in apparent form.

Forecasting↗

PubMedDate not supplied

Thermoregulatory responses in post-coronary artery bypass surgery and healthy males during moderate exercise in warm and cool environments.

PURPOSE: The purpose of this study was to determine and compare the thermoregulatory and hemodynamic responses to moderate intensity exercise (60% of peak oxygen consumption [.VO(2peak)]) in warm (35 degrees C, 45% relative humidity) and cool (18 degrees C, 65% relative humidity) environments in men who had previously undergone coronary artery bypass graft (CABG) surgery and healthy control subjects, matched for age and body composition. METHODS: Fourteen post-CABG men and 16 healthy control subjects were recruited and walked 40 minutes at a moderate intensity, in randomized order, in warm and cool environments (on separate days). Measures of heart rate, systolic and diastolic blood pressures, rating of perceived exertion, core (rectal)(T(c)) and mean skin temperatures (T(sk)), oxygen consumption (.VO(2peak)), sweat rate, and blood lactate were taken. RESULTS: Both groups showed a larger increase (P <.05) in T(c) and rate-pressure product during exercise in the warm compared with the cool environment. However, T(c) and rate pressure product were significantly lower (P <.05), and systolic blood pressure decreased slightly with exercise duration (P <.05) in the CABG group compared with the control group in the warm environment. Heart rate, T(sk), percent .VO(2peak), blood lactate, sweat rate, and rating of perceived exertion did not differ significantly between the groups in either climate and no subject had ischemia or arrhythmia during test procedures. CONCLUSIONS: These results indicate that clinically stable men with revascularized coronary artery disease are able to cope as well as healthy controls with the thermoregulatory and cardiovascular demands of 40 minutes of moderate intensity exercise in warm and cool environments.

Adult↗

PubMed2006

Altered gut flora and environment in patients with severe SIRS.

BACKGROUND: The gut is considered an important target organ of injury after severe insult such as sepsis, trauma, and shock. The impact of bacterial translocation or mesenteric lymph on systemic inflammatory response and multiple organ damage has been investigated in animals, but dynamic changes in the gut flora and environment have not been fully clarified in critically ill patients. In the present study, we quantitatively evaluated changes in the gut microflora and environment in patients with severe systemic inflammatory response syndrome (SIRS). METHODS: Twenty-five patients with severe SIRS, who fulfilled the criteria for SIRS, had a serum CRP level >10 mg/dL, and were treated in the intensive care unit for more than 2 days, were included in our study. SIRS was a result of sepsis in 18 patients, trauma in 6, and burn in 1. A fecal sample was used for quantitative evaluation of microflora (bacterial counts of 10 key groups including Bifidobacterium and Lactobacillus) by plate or tube technique and of the gut environment (pH and 9 organic acids by high speed liquid chromatography). Data obtained from patients were compared with corresponding data from healthy volunteers. RESULTS: Analysis of fecal flora confirmed that patients with severe SIRS had significantly lower total anaerobic bacterial counts (especially 2-4 log fewer "beneficial" Bifidobacterium and Lactobacillus) and 2 log higher "pathogenic" Staphylococcus and Pseudomonas group counts than those of healthy volunteers. Concentrations of total organic acids (especially "beneficial" short-chain fatty acids such as acetic acid, propionic acid, and butyric acid) in the feces were significantly decreased in the patients, whereas pH was markedly increased. CONCLUSIONS: The gut flora and environment are significantly altered in patients with severe SIRS. Abnormal gut flora and environment may affect systemic inflammatory response after severe insult.

Adult↗

PubMed2006

Insects from the grazing food web favoured the evolutionary habitat shift to bright environments in araneoid spiders.

The Araneoidea comprises a diverse group of web-building spiders, and part of this diversity is believed attributable to habitat expansion to bright environments. We clarified the fitness-related advantages of living in such environments by examining prey availability and the growth rates of 10 species in three families inhabiting grassland (bright) and forest understory (dim) habitats. Spiders in the grassland habitat captured more prey, derived mainly from the grazing food web, than those in the forest-floor environment, and this difference was manifested in their growth rate. Independent contrasts indicated that increased utilization of insects from the grazing food web led to an evolutionary increase in adult body size. These results suggest that the shift to bright environments enabled araneoid spiders to evolve diverse life-history traits, including rapid growth and large size, which were not possible in dim environments.

Analysis of Variance↗

PubMed1990

Auditory warning sounds in the work environment.

One of the most common auditory warnings is the ambulance 'siren'. It cuts through traffic noise and commands one's attention, but it does so by sheer brute force. This 'better safe than sorry' approach to auditory warnings occurs in most environments where sounds are used to signal danger or potential danger. Flooding the environment with sound is certain to attract attention; however it also causes startled reactions and prevents communications at a crucial point in time. In collaboration with several companies and government departments, the MRC Applied Psychology Unit performed a series of auditory warning studies. The main conclusions of the research were that the number of immediate-action warning sounds should not exceed about six, and that each sound should have a distinct melody and temporal pattern. The experiments also showed that it is possible to predict the optimum sound level for a warning sound in most noise environments. Subsequently, a set of guidelines for the production of ergonomic auditory warnings was developed. The guidelines have been used to analyse the environments in both fixed-wing and rotary-wing aircraft, and to design prototype warning systems for environments as diverse as helicopters, operating theatres and the railways.

Auditory Threshold↗