Genomic analysis of the differential response to experimental infection with porcine circovirus 2b.

Porcine circovirus type 2 (PCV2) is the etiological agent of a group of associated diseases (PCVAD) that affect production efficiency and can lead to mortality. Using different crossbred lines of pigs, we analyzed host genetic variation of viral load, immune response and weight change following experimental infection with a PCV2b strain (n = 386). Pigs expressed variation in the magnitude and initiation of viremia and immune response recorded weekly until 28 days post-infection. A higher viral load was correlated with weight gain (r = -0.26, P < 0.0001) and presence of PCV2-specific antibodies (IgM, r = 0.26-0.34, P < 0.0001; IgG, r = 0.17-0.20, P < 0.01). In genome-wide association analyses of the responses at different time points, the proportions of phenotypic variation explained by combined effects of 56 433 SNPs were 34.8-59.4% for viremia, 10.1-59.5% for antibody response and 5.6-14.9% for weight change. Relationships between genomic prediction of overall viral load and weight gain during the first weeks of challenge were negative (-0.21 and -0.24 respectively, P < 0.0001). Individuals that carried more favorable alleles across three SNPs on SSC9 (0.60 Mb) and SSC12 (6.8 and 18.2 Mb) partially explained this relationship, having lower viral load (P < 0.0001); lower viremia at day 14 (P < 0.0001), day 21 (P < 0.01) and day 28 (P < 0.05) and greater overall average daily gain during infection (ADGi ; P < 0.01), ADGi at week 3 (P < 0.001) and week 4 (P < 0.01). These additive genetic relationships could lead to molecular solutions to improve animal health and reduce production costs.

Work stress and depression among direct support professionals: the role of work support and locus of control.

BACKGROUND: Although work stress can impede the capacity of direct support professionals and contribute to mental health challenges, external (i.e. work social support) and internal resources (i.e. an internal locus of control) have been shown to help DSPs cope more actively. We examined how work stress was associated with depression, with a particular focus on the role of resources. METHOD: Direct support professionals (n = 323) who serve adults with intellectual and developmental disabilities from five community-based organisations completed a cross-sectional, self-administered survey which measured work stress, work support, locus of control, and depression. RESULTS: Multiple regression analyses demonstrated that work stress was positively associated with depression, while resources were negatively associated with depression. In particular, work support moderated the effects of client disability stress, supervisory support lessened the effects of role conflict, and locus of control moderated the effects of workload. CONCLUSIONS: Such findings suggest the importance of external and internal resources for staff mental health. This research underscores the need for strong work social support systems and interventions to help staff manage work stressors.

Persistent and aggressive interactions with the police: potential mental health implications.

AIMS: Little is known about the potential health impact of police encounters despite a ubiquitous police presence in many disadvantaged urban environments. In this paper, we assess whether persistent or aggressive interactions with the police are associated with poor mental health outcomes in a sample of primarily low-income communities of colour in Chicago. METHODS: Between March 2015 and September 2016, we surveyed 1543 adults in ten diverse Chicago communities using a multistage probability design. The survey had over 350 questions on health and social factors, including police exposure and mental health status. We use sex-stratified logistic regression to examine associations between persistent police exposure (defined as a high number of lifetime police stops) or aggressive police exposure (defined as threat or use of police force during the respondent's most recent police stop) and the presence of post-traumatic stress disorder (PTSD) or depressive symptoms. RESULTS: Men reporting a high number of lifetime police stops have three times greater odds of current PTSD symptoms compared with men who did not report high lifetime police stops (OR 3.1, 95% CI 1.3-7.6), after adjusting for respondent age, race/ethnicity, education, history of homelessness, prior diagnosis of PTSD and neighbourhood violent crime rate. Women reporting a high number of lifetime police stops have two times greater odds of current PTSD symptoms, although the results are not statistically significant after adjustment (OR 2.0, 95% CI 0.9-4.2). Neither persistent nor aggressive police exposure is significantly associated with current depressive symptoms in our sample. CONCLUSIONS: Our findings support existing preliminary evidence of an association between high lifetime police stops and PTSD symptoms. If future research can confirm as causal, these results have considerable public health implications given the frequent interaction between police and residents in disadvantaged communities in large urban areas.

Effect of a National Cancer Institute Clinical Alert on breast cancer practice patterns.

PURPOSE: This study evaluates the effect of the 1988 National Cancer Institute Clinical Alert regarding treatment of early-stage breast cancer on the patterns of treatment provided to patients. PATIENTS AND METHODS: Data analyzed were collected from the hospital and outpatient records of 12,534 female patients with a primary diagnosis of breast cancer (stages I and II) initially diagnosed during the years 1983 through 1989. RESULTS: Analyses revealed that the proportions of patients with a negative lymph node status diagnosed after the May 1988 Clinical Alert who received adjuvant treatment (tamoxifen and/or multidrug chemotherapy) were significantly greater than predicted from treatment trends established before the Alert's release. Proportions of patients with positive lymph node status receiving adjuvant therapy subsequent to the Alert's release, in contrast, did not fall outside the projected confidence intervals for that group. Additional analyses showed a significant effect of the Clinical Alert among several subgroups of node-negative patients. CONCLUSION: Findings suggest that the Clinical Alert mechanism, followed by publication in the peer-reviewed scientific literature, is an effective way to communicate important research findings to practitioners in the community. However, the Alert mechanism is controversial and should be used judiciously to ensure its credibility.

Carcass composition of market weight pigs subjected to heat stress in utero and during finishing.

Objectives were to investigate the effects of prolonged gestational and/or postnatal heat stress on performance and carcass composition of market weight pigs. Pregnant gilts were exposed to gestational heat stress (GHS, 28°C to 34°C, diurnal) or thermal neutral (18°C to 22°C, diurnal) conditions during the entire gestation or during the first or second half of gestation. At 14 wk of age (58 ± 5 kg), barrows were housed in heat stress (32°C, HS) or thermal neutral (21°C, TN) conditions. Feed intake and BW were recorded weekly, and body temperature parameters were monitored twice weekly until slaughter (109 ± 5 kg). Organs were removed and weighed, and loin eye area (LEA) and back fat thickness (BF) were measured after carcass chilling. Carcass sides were separated into lean, separable fat, bone, and skin components and were weighed. Moisture, lipid, and protein content were determined in the LM at the 10th rib. Data were analyzed using a split plot with random effect of dam nested within gestational treatment. Carcass measurements included HCW as a covariate to control for weight. Planned orthogonal contrast statements were used to evaluate the overall effect of GHS in the first half, second half, or any part of gestation. Gestational heat stress did not alter postnatal performance or most body temperature parameters (P > 0.10). However, ADFI in the finishing period was increased (P < 0.05) in response to GHS, particularly in pigs receiving GHS in the first half of gestation. Gestational heat stress during the first half of gestation decreased head weight as a percent of BW (P = 0.02), whereas GHS in the second half of gestation decreased bone weight as a percent of BW (P = 0.02). Heat stress reduced ADG, BW, and HCW (P < 0.0001). Lean tissue was increased in HS pigs on both a weight and percentage basis (P < 0.0001), but LEA was similar to TN carcasses (P = 0.38). Carcasses from HS barrows also had less carcass separable fat (P < 0.01) and tended to have less BF (P = 0.06) compared with those from TN barrows, even after controlling for HCW. However, percent intramuscular fat did not differ between treatments (P = 0.48). The LM from HS carcasses had a greater moisture to protein ratio (P = 0.04). HS barrows also had decreased heart (P < 0.001) and kidney (P < 0.0001) as a percent of BW compared with TN pigs. In summary, GHS may affect head and bone development, subsequently affecting carcass composition. Chronic HS during finishing results in longer times to reach market weight and a leaner carcass once market weight is achieved.

2-Indanpropionic acids: structural leads for prostaglandin F2alpha antagonist development.

A rationale is presented for the development of prostaglandin F2alpha receptor antagonists. The target analogue, 5,6-(dibenzyloxy)-1-oxo-2-propyl-2-indanpropionic acid (3), was shown to have selective activity for antagonism of PGF2alpha when compared to the antagonism of acetylcholine and KCl on the mouse ileum, whereas other 2-indanpropionic acids (1, 2, 4), not substituted with benzyl functions, were considerably less active and nonselective. The results suggest that 3 may serve as a lead compound for further drug development.

Improving question wording in surveys of culturally diverse populations.

PURPOSE: The purpose of this paper is to briefly describe a theoretical model articulating cognitive theory and sources of potential response bias resulting from racial or ethnic cultural experience to survey questions that deal with health behavior. The theory components are then evaluated using questions obtained from national health surveys conducted by the National Center for Health Statistics and Centers for Disease Control and Prevention. The analysis explores the effects of four cognitive tasks involved in responding to questions as specified by the model: question interpretation, information retrieval from memory, judgment formation, and response editing. Implications for epidemiological research are considered. METHODS: Data were collected from a purposive sample of 423 adults aged 18 through 50 who were recruited to ensure equal numbers of African American, Puerto Rican, Mexican American, and non-Hispanic white respondents, stratified by age, gender, and education. Individual questions were selected for evaluation to ensure variation by topic and question format. Probes related to each of the cognitive tasks were designed to obtain insight into the underlying cognitive processes used by respondents to answer survey questions. All statistical analyses used logistic regression or ordinary least squares multiple regression as appropriate. RESULTS: Variation by race/ethnicity was found in the way respondents defined physical activity in a series of questions used in the Centers for Disease Control and Prevention Behavioral Risk Factor Surveillance System (BRFSS). Gender and race/ethnicity appeared to influence interpretation in the absence of specific cues in the question format about how to respond. Strategies used to retrieve information from memory did not appear to be influenced by respondent culture; however, frequency of the event was associated with the recall strategy in that more frequent or regular events were more likely to result in estimates about frequency, whereas unusual or seldom occurring events were counted. Effects of race/ethnicity on judgment formation seem to be reflected in the propensity of respondents' willingness to use extreme response categories. Most effects due to race/ethnicity were found in respondent editing of answers. Race/ethnicity was found to be associated with a social desirability trait; with willingness to disclose socially undesirable behavior, particularly to interviews from racial or ethnic groups that differed from the respondent; and with the tendency to overreport socially desirable behavior. CONCLUSIONS: Overall, the results of this research suggest several ways in which the validity of questions about risk behavior can be improved. In designing such questions, the investigator should envision the interview as a structured conversation in which ordinary conversational norms apply. Thus, questions that might request redundant information or that are threatening to the respondent need to be asked in ways that minimize these effects. Using interviewers of the same racial or ethnic group is important. Attending to the order of questions to ensure that redundant information is not requested is important. Writing questions to ensure that where response cues occur they lead the respondent to answer in unbiased ways is also important. Testing questions for potential racial or ethnic bias before using them is also important, even if the questions have been used successfully with population groups other than that or those included in a study.

The reliability of self-reported age of onset of tobacco, alcohol and illicit drug use.

AIMS: To examine the reliability of self-reported age of first substance use experiences among national samples of adult and child respondents. DESIGN: Survey responses from seven waves of the National Longitudinal Survey of Youth (NLSY) were examined. PARTICIPANTS: Adult and child NLSY respondents reporting age of first tobacco, alcohol, marijuana, cocaine and/or crack use during two or more survey interviews. MEASUREMENTS: Four indicators of reliability: intraclass correlation coefficients (ICC), mean and absolute mean differences in reported age and reports consistent within 1 year. FINDINGS: The adjusted mean ICC for all comparisons was 0.69. The adjusted mean difference in self-reported age of first substance use was -0.52 years and the adjusted absolute mean difference was 2.00 years. The adjusted percentage of all comparisons reporting ages consistent within 1 year was 55.28%. More consistent reports were provided by adults, and in response to questions posed over 2 years as opposed to longer time intervals. Respondent answers to questions concerned with first use of marijuana were generally found to be most reliable; questions concerned with first use of crack were least reliable and reports of tobacco, alcohol and cocaine were intermediate. Logistic regression analyses also identified age, race, gender, education and poverty status as predictors of consistent reporting. CONCLUSIONS: Self-reports of age of first substance use experiences, as currently collected via survey questionnaires, are of sufficient reliability for most current epidemiological applications. For inquiries where age of substance use onset is itself a research focus, however, researchers should invest additional effort in improving the reliability of measurement.

Substance abuse and homelessness: social selection or social adaptation?

Although substance abuse has for many years been documented as a serious problem among homeless populations, there is as yet no clear understanding of the nature of the relationship between substance abuse and homelessness. We evaluate alternative social selection and social adaptation models of this process. Using data from a random probability sample, the substance abuse and homeless experiences of 303 homeless people and people at risk of homelessness in Cook County, Illinois, were investigated. Proportional hazards regression models were employed to assess both social selection and social adaptation models. Drug but not alcohol abuse was associated with first homeless episode. Prior homeless experiences were found to be predictive of first symptoms of both alcohol and drug abuse. Other variables, including the availability of social and economic resources, were also associated with each of these outcomes. Models of both selection and adaptation processes are necessary to account for the association between homelessness and substance abuse, indicating that a multi-directional model is more appropriate. In addition findings suggest that, in recent years, drugs may have displaced alcohol as an important precursor of homelessness for many individuals.

Effects of pravastatin on plasma lipid concentrations in poloxamer 407-induced hyperlipidemic rats.

A new animal model of hyperlipidemia is being developed using the nonionic surfactant poloxamer 407 (P-407). We investigated the impact of pravastatin on P-407-induced hyperlipidemia. Twenty rats received P-407 300 mg intraperitoneally to induce hyperlipidemia, and 20 control rats received saline injection. Pravastatin was administered orally to an equal number of rats in both groups using three different regimens. A fourth group did not receive pravastatin. At 24 hours after injection, total cholesterol levels in two of the pravastatin groups were 28% and 34% lower than those in animals that did not receive pravastatin (p < or = 0.01). At 48 hours, triglyceride levels were significantly lower in all pravastatin groups (21-44%) versus animals not receiving pravastatin. Pravastatin diminished the effects of P-407 on lipoproteins. This new animal model may be useful in screening for investigational antihyperlipidemic agents.

Predictive validity of the American Board of Family Practice In-Training Examination.

Most research into the validity of graduate medical education in-training examinations has focused on construct validity and concurrent validity issues. This study examined the predictive validity of the American Board of Family Practice In-Training Examination using multivariate analysis of all U.S. family practice residents who took the certification examination in either 1987 or 1988. Results of these two certification examinations were analyzed for the cohorts of physicians who had taken in-training examinations as first-, second-, and third-year residents. Multiple regression analysis showed that the composite score, and all but one part-score, of each in-training examination were independently predictive of performance on the certification examination. This study also found that the older residents did less well on the certification exam, and that men and women each did better on selected portions of the examination. The implications of these findings for in-training examinations in other specialties and for program directors and residents are discussed.

Self-reported risk factors for AIDS among homeless youth.

This study assessed HIV risk behaviors in a sample of homeless youth in a large urban area and examined factors associated with these behaviors. Self-reported behaviors were assessed via interviews with 196 homeless youth in Chicago in all 10 urban shelters serving this group and in 5 street locations. Overall, 83.7% reported at least one of these risk factors: multiple sex partners; high-risk partners; inconsistent condom use; history of sexually transmitted disease; anal sex; prostitution; and/or intravenous drug use. An index of these behaviors was associated with being male, having unmet personal needs, being interviewed in street locations, and having a history of sexual abuse. Findings suggest that strategies that may decrease risk behaviors among homeless youth include the elimination of their need to rely on illicit activities for income, provision of basic needs, education regarding existing services, increased outreach efforts, and early identification of and protection from childhood sexual abuse.

Improving the self reporting of tobacco use: results of a factorial experiment.

OBJECTIVES: To examine divergent estimates of smoking prevalence in two random digit dial surveys for the same population. Based upon internal and external reviews of survey procedures, differences in survey introductions (general health versus tobacco specific introduction) and/or differences in the use of filter questions were identified as the most likely explanations. This prompted an experiment designed to investigate these potential sources of measurement error. DESIGN: A randomised 2 x 2 factorial experiment. SETTING: A random digit dial telephone survey from July to September 2000. SUBJECTS: 3996 adult Californian respondents. MAIN OUTCOME MEASURES: A series of smoking prevalence questions in the context of a tobacco or general health survey. RESULTS: Logistic regression analyses suggest that, among females, prior knowledge (from the survey introduction) that a survey is concerned with tobacco use may decrease self reported smoking prevalence (approximately 4% absolute prevalence difference). Differences in the use of filter questions resulted in almost no misclassification of respondents. CONCLUSIONS: The tobacco specific survey introduction is causing some smokers to deny their tobacco use. The data suggest that these smokers tend to be women that smoked occasionally. A desire by the participants to minimise their personal time costs or a growing social disapproval of tobacco use in the USA may be contributing to the creation of previously undetected survey artefacts in the measurement of tobacco related behaviours.

Mental health, social relations, and social selection: a longitudinal analysis.

A wide body of literature documents the effect of social networks and social supports on mental health. Fewer studies, however, have examined the reciprocal effect of mental health on social relationships. This problem is examined using data from a national panel survey of adults aged 20-64. For the sample as a whole, support was found for a social selection process, since psychological distress predicted decreases in primary, but not secondary, social relationships. The extent of primary relationships also were found to be associated with subsequent distress, providing evidence that the relationship between mental health and social environment may be transactional. When examined separately by gender, males but not females were found to be vulnerable to the process of social selection, supporting the hypothesis that the expression of distress is less role-appropriate for men and therefore more likely to invite social sanctions. Social causation effects also were observed only among males.

Changes in self-efficacy and readiness for smoking cessation among women with high school or less education.

The most common theory of smoking cessation postulates that readiness to quit begins with changes in attitudes that move the smoker toward behavioral change and eventual cessation. However, trends in smoking indicate that many who currently smoke are not ready to quit. Hence, strategies that both enhance readiness and focus on quitting are likely to be most effective. We hypothesize that an intervention addressed to motivating behavior change will enhance readiness to change, which will in turn increase the smokers self-efficacy regarding further change. A smoking cessation intervention that combined a self-help booklet and televised segments was developed to address these issues in a population of women smokers with high school or less education. Readiness to quit was measured prior to the intervention, immediately following the intervention, and again at six and 12 months after intervention. The results indicate that the intervention had its effects on readiness to quit, which in turn affected self-efficacy, which further enhanced readiness to quit. These findings indicate that interventions aimed at this group of smokers may need to provide achievable objectives that focus on preparing the smoker to quit as well as promote cessation.

Monthly variations in self-reports of alcohol consumption.

OBJECTIVE: This study examines monthly variation in reports of recent alcohol consumption behavior. METHOD: Telephone survey data collected by the Behavioral Risk Factor Surveillance System were used to measure self-reports of drinking and heavy episodic drinking in the 30 days before the interview. The sample (N = 57,758) comprised cases collected in six states in 5 selected years. Monthly variability in self-reported alcohol consumption was evaluated by logistic regression analysis, using "deviation from means coding" for the month of interview, with background variables and year of interview controlled and state-level clustering adjusted. RESULTS: Adults were significantly more likely to report past 30-day alcohol consumption when interviewed during the month of January and less likely to report consumption when interviewed during March. Respondents were also more likely to report heavy episodic drinking during the month of July. Despite large differences in alcohol consumption between male and female participants, these seasonal patterns were essentially the same for both genders. CONCLUSIONS: The findings suggest that assessments of alcohol consumption that do not consider seasonal variation may be biased. In order to minimize this bias, it is recommended that researchers avoid collecting data only during these particular times of the year or extend the data collection interval and control for seasonal variability.

Interviewer effects on self-reported substance use among homeless persons.

This study examines respondent editing of survey responses to questions regarding substance use. Previous research has identified several types of interviewer effects that may be associated with respondent editing, including direct and social distance effects. Little is known, however, regarding how these potential effects may influence self-reported substance use behavior. Data analyzed for this study were collected as part of a survey of substance use among homeless persons conducted in Cook County, Illinois. A total of 481 respondents were sampled at random in emergency and transitional shelters, soup kitchens, drop-in centers, and single room occupancy (SRO) hotels. Overall, a direct, gender-based effect was observed, with homeless respondents of both genders more willing to reveal substance use behaviors to male interviewers. Some race- and age-related direct effects were also identified, with White and older interviewers obtaining more reports of substance use. These findings yield important evidence regarding respondent editing of self-reported substance use and have implications for the common practice of demographically matching interviewers and respondents.

Evaluation of medical center support for rural physicians.

Professional isolation remains a problem for rural physicians. To address the problem, a university medical center established a Physician Support Office (PSO). The PSO offered rural physicians toll-free telephone access to patient referral, patient follow-up, library reference, and drug information services. A newsletter was also published. The service was evaluated using a quasi-experimental design. Physicians in the experimental area felt there was improvement in several medical center services, compared to physicians in the control area. Provision of library services, referral services and a newsletter contributed significantly to the usefulness of the PSO program. Nevertheless, the PSO did not produce a significant improvement in rural physicians' overall feeling of general medical center support.

The influence of rural physicians' perception on referral patterns to a university hospital.

The patient referral process is based on a complex set of social rewards and costs for the referring physician. For the physician or institution potentially receiving referrals, a key question is, why is one institution selected over other available choices? Factor analysis of a survey of rural physicians revealed five factors of reward and cost associated with the choice of where to refer patients. Further analysis of these factors suggested that the ability to have patients admitted and treated when necessary is central to the satisfaction of the referring physician and their willingness to continue the consultant relationship. Adequate information about the consultants was also important to satisfaction. Other factors have less influence. Further, "admissions when necessary" was the only reward/cost factor which predicted physicians who referred more to the university hospital than to other hospitals. If a university hospital wants to develop strategies to encourage referrals from rural physicians, it must be cognizant of these social reward-cost factors.

A viscoelastic, viscoplastic model of cortical bone valid at low and high strain rates.

The stress-strain behavior of cortical bone is well known to be strain-rate dependent, exhibiting both viscoelastic and viscoplastic behavior. Viscoelasticity has been demonstrated in literature data with initial modulus increasing by more than a factor of 2 as applied strain rate is increased from 0.001 to 1500 s(-1). A strong dependence of yield on strain rate has also been reported in the literature, with the yield stress at 250 s(-1) having been observed to be more than twice that at 0.001 s(-1), demonstrating the material viscoplasticity. Constitutive models which capture this rate-dependent behavior from very low to very high strain rates are required in order to model and simulate the full range of loading conditions which may be experienced in vivo; particularly those involving impact, ballistic and blast events. This paper proposes a new viscoelastic, viscoplastic constitutive model which has been developed to meet these requirements. The model is fitted to three sets of stress-strain measurements from the literature and shown to be valid at strain rates ranging over seven orders of magnitude.