Importance of dispersal routes that minimize open-ocean movement to the genetic structure of island populations.

Islands present a unique scenario in conservation biology, offering refuge yet imposing limitations on insular populations. The Kimberley region of northwestern Australia has more than 2500 islands that have recently come into focus as substantial conservation resources. It is therefore of great interest for managers to understand the driving forces of genetic structure of species within these island archipelagos. We used the ubiquitous bar-shouldered skink (Ctenotus inornatus) as a model species to represent the influence of landscape factors on genetic structure across the Kimberley islands. On 41 islands and 4 mainland locations in a remote area of Australia, we genotyped individuals across 18 nuclear (microsatellite) markers. Measures of genetic differentiation and diversity were used in two complementary analyses. We used circuit theory and Mantel tests to examine the influence of the landscape matrix on population connectivity and linear regression and model selection based on Akaike's information criterion to investigate landscape controls on genetic diversity. Genetic differentiation between islands was best predicted with circuit-theory models that accounted for the large difference in resistance to dispersal between land and ocean. In contrast, straight-line distances were unrelated to either resistance distances or genetic differentiation. Instead, connectivity was determined by island-hopping routes that allow organisms to minimize the distance of difficult ocean passages. Island populations of C. inornatus retained varying degrees of genetic diversity (NA = 1.83 - 7.39), but it was greatest on islands closer to the mainland, in terms of resistance-distance units. In contrast, genetic diversity was unrelated to island size. Our results highlight the potential for islands to contribute to both theoretical and applied conservation, provide strong evidence of the driving forces of population structure within undisturbed landscapes, and identify the islands most valuable for conservation based on their contributions to gene flow and genetic diversity.

Primary anti-viral cytotoxic T-cell responses in semiallogeneic chimeras are not absolutely restricted to host H-2 type.

Chimeras produced by reconstitution of 950 rads irradiated type A or type B host mice with (AXB)F1 fetal liver stem cells were examined in primary (in vivo) and secondary (in vitro) Tc-cell responses to ectromelia virus infection. Of 33 individual chimeras which gave primary responses, 26 produced significant specific lysis of infected targets of both A and B type, though host type targets were invariably lysed more efficiently (host bias). The other 7 chimeras gave lysis of infected host type targets only (absolute restriction). 12 individual chimeras were used in secondary responses. Nine showed host bias, and three showed absolute restriction. Whether an individual chimera showed host bias or absolute restriction seemed to be unrelated to whether the response was primary or secondary, to the time after reconstitution (ranging from 4 to 22 wk), to strain of mouse, or to the batch of fetal liver stem cells used.

Heterogeneity and specificity of cloned lines of influenza-virus specific cytotoxic T lymphocytes.

Continuous lines of murine cytotoxic T lymphocytes (CTL) directed to type A influenza viruses have been generated in vitro by stimulation of individual CTL precursors in the presence of T cell-growth factor TCGF and syngeneic virus-infected stimulator cells. The cloned CTL lines are H-2 restricted in their target cell recognition and exhibit distinct patterns of influenza virus recognition. All CTL lines appear to be restricted in target cell recognition to either the H-2K or the H-2D end of the appropriate H-2 haplotype. Likewise, CTL lines of F1 origin are restricted in recognition exclusively to one of the parental haplotypes. All CTL lines examined express the Thy-1.2 and the Lyt-2-surface antigen markers. 4 of 11 cytotoxic lines examined also expressed detectable levels of the Lyt-1- surface antigen. These findings confirm at the clonal level previous observations on the H-2K/D restriction of virus-specific CTL and also demonstrate heterogeneity among H-2 restricted CTL both from the standpoint of viral antigen recognition and cell surface phenotype.

Simultaneous expression of H-2-restricted and alloreactive recognition by a cloned line of influenza virus-specific cytotoxic T lymphocytes.

Based on theoretical considerations and several types of experimental evidence with heterogeneous cell populations it has been proposed that alloreactive T cells and major histocompatibility complex (MHC)-restricted T cells directed to foreign non-NHC antigens represent overlapping subsets. In this report we provide direct evidence for this hypothesis at the clonal level. We have isolated a cloned continuous influenza virus-specific cytotoxic T cell (CTL) line derived from a single (H-2b X H-2d)F1 CTL precursor which simultaneously exhibits H-2-restricted cytotoxicity of influenza A/Japan/305/57 virus in association with H-2Kd and alloreactive cytotoxicity for H-2Kk alloantigen. Cold target inhibition data demonstrate that both MHC-restricted and alloreactive recognition is mediated by the same cell population. In addition to cross-reactivity at the target cell level, we shown that this cloned CTL line can be specifically stimulated to proliferate either by A/Japan/305/57 virus-infected cells expressing H-2Kd or by uninfected cells of the H-2Kk haplotype.

Sendai virus-specific, H-2-restricted cytotoxic T lymphocyte responses of nude mice grafted with allogeneic or semi-allogeneic thymus glands.

The in vitro secondary cytotoxic T lymphocyte (CTL) response to Sendai virus-treated stimulator cells by primed spleen cells from thymus gland-grafted nude mice was examined. BALB/c (H-2d) nude mice grafted with allogeneic C57BL/10 (H-2b) thymus glands developed CTL responses directed exclusively to Sendai virus-infected H-2d target cells. (C57BL/6 X BALB/c)F1 nude mice grafted with thymus glands of either parent developed CTL responses preferentially against infected target cells expressing the MHC antigens present in the parental thymus graft, but also had detectable activity for infected target cells of the parental haplotype not expressed in the thymus. These results provide evidence against the concept that self recognition by MHC-restricted CTL is directed exclusively by the MCH type of the thymus.

Associations of burnout with awakening and diurnal cortisol among police officers.

The aim of this cross-sectional study was to assess the associations of burnout with cortisol parameters in 197 police officers from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study (2010-2014). The Maslach Burnout Inventory-General Survey assessed depersonalization, exhaustion, and professional efficacy. Officers provided salivary cortisol samples collected upon awakening, and 15, 30, and 45 min thereafter as well as three additional samples at lunchtime, dinnertime, and bedtime. Total area under the curve with respect to increase (AUCWI for waking and AUCDI for diurnal), total area under the curve with respect to ground (AUCWG for waking and AUCDG for diurnal), and diurnal slope were determined and used in this study. Unadjusted and adjusted (age, sex, and race/ethnicity) associations were examined using linear regression. The mean age of the officers was 48 years and 72% were males. The depersonalization component of burnout was negatively associated with AUCDG (ß = -108.4; p = 0.036). Similarly, as exhaustion increased, AUCWI (ß = -9.58, p = 0.038), AUCDG (ß = -114.7, p = 0.029) and the diurnal slope (ß = -0.000038; p = 0.017) decreased. The Professional efficacy was not associated with any of the cortisol parameters. These results suggest that certain characteristics of burnout may be associated with diminished cortisol secretion in this group of urban police officers. Our findings add to previous studies examining associations of burnout with the cortisol awakening response. Future longitudinal studies are needed to evaluate the temporal relationship between burnout and these cortisol parameters.

Dimensional analysis of actigraphic derived sleep data.

Nonlinear dimensional analyses can be a useful tool in understanding the underlying behavior of dynamical systems, including biological systems. Many biological functions can be modeled as chaotic processes, including sleep. Sleep data can be obtained from several methods, such as electroencephalograms, polysomnography, and actigraph. Actigraphy, because of its low level of invasiveness, is an increasingly popular method of obtaining sleep data. This study analyzed actigraphy data with nonlinear dimensional analyses to determine if such analytic methods would be useful in sleep studies. Participants wore actigraphs on their wrists, which recorded movement for several days. Several sleep quality variables, such as movement during sleep and total sleep time, were derived from these sleep data. These variables were used to determine whether the quality of sleep was good or poor. Lagged phase space plots were graphed and nonlinear parameters for the fractal dimension and the correlation dimension were computed for each participant. Descriptive and inferential statistics were performed to determine if the nonlinear parameters showed significant differences with respect to sleep quality.

Estimation of the maximum flow-mediated brachial artery response using local regression methods.

We consider methods for estimating the maximum from a sequence of measurements of flow-mediated diameter of the brachial artery. Flow-mediated vasodilation (FMD) is represented using the maximum change from a baseline diameter measurement after the release of a blood pressure cuff that has been inflated to reduce flow in the brachial artery. The influence of the measurement error on the maximum diameter from raw data can lead to overestimation of the average maximum change from the baseline for a sample of individuals. Nonparametric regression models provide a potential means for dealing with this problem. When using this approach, it is necessary to make a judicious choice of regression methods and smoothing parameters to avoid overestimation or underestimation of FMD. This study presents results from simulation studies using kernel-based local linear regression methods that characterize the relationship between the measurement error, smoothing and bias in estimates of FMD. Comparisons between fixed or constant smoothing and automated smoothing parameter selection using the generalized cross validation (GCV) statistic are made, and it is shown that GCV-optimized smoothing may over-smooth or under-smooth depending on the heart rate, measurement error and measurement frequency. We also present an example using measured data from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) pilot study. In this example, smoothing resulted in lower estimates of FMD and there was no clear evidence of an optimal smoothing level. The choice to use smoothing and the appropriate smoothing level to use may depend on the application.

A new descriptor selection scheme for SVM in unbalanced class problem: a case study using skin sensitisation dataset.

A novel descriptor selection scheme for Support Vector Machine (SVM) classification method has been proposed and its utility demonstrated using a skin sensitisation dataset as an example. A backward elimination procedure, guided by mean accuracy (the average of specificity and sensitivity) of a leave-one-out cross validation, is devised for the SVM. Subsets of descriptors were first selected using a sequential t-test filter or a Random Forest filter, before backward elimination was applied. Different kernels for SVM were compared using this descriptor selection scheme. The Radial Basis Function (RBF) kernel worked best when a sequential t-test filter was adopted. The highest mean accuracy, 84.9%, was obtained using SVM with 23 descriptors. The sensitivity and the specificity were as high as 93.1% and 76.6%, respectively. A linear kernel was found to be optimal when a Random Forest filter was used. The performance using 24 descriptors was comparable with a RBF kernel with a sequential t-test filter. As a comparison, Fisher's linear discriminant analysis (LDA) under the same descriptor selection scheme was carried out. SVM was shown to outperform the LDA.

A statistical test to determine the quality of accelerometer data.

Accelerometer data quality can be inadequate due to data corruption or to non-compliance of the subject with regard to study protocols. We propose a simple statistical test to determine if accelerometer data are of good quality and can be used for analysis or if the data are of poor quality and should be discarded. We tested several data evaluation methods using a group of 105 subjects who wore Motionlogger actigraphs (Ambulatory Monitoring, Inc.) over a 15 day period to assess sleep quality in a study of health outcomes associated with stress among police officers. Using leave-one-out cross-validation and calibration-testing methods of discrimination statistics, error rates for the methods ranged from 0.0167 to 0.4046. We found that the best method was to use the overall average distance between consecutive time points and the overall average mean amplitude of consecutive time points. These values gave us a classification error rate of 0.0167. The average distance between points is a measure of smoothness in the data, and the average mean amplitude between points gave an average reading. Both of these values were then normed to determine a final statistic, K, which was then compared to a cut-off value, K(C), to determine data quality.

Class I MHC-restricted cytotoxic T cells efficiently recognize haemagglutinin that is defective in protein folding and cell surface expressions.

Cytotoxic T-cell recognition of an engineered variant of the influenza viral haemagglutinin (HA), expressed in vaccinia virus, was investigated. We show that the insertion of a Foot-and-Mouth Disease virus (FMDV) immunogenic peptide into the HA results in major disruption of its higher order structure with intracellular rather than cell surface localization accompanying the loss of conformational epitopes detected by antibody. In contradistinction to antibody, recognition of the chimaeric molecule by HA-specific class I-restricted cytotoxic T-cells was unimpaired, demonstrating that class I-specific T-cells recognize, in majority, continuous epitopes rather than conformational epitopes in the HA.

A general method for the construction of recombinant vaccinia viruses expressing multiple foreign genes.

Plasmid vectors with multiple cloning sites adjacent to a vaccinia virus (VV) promoter were constructed and used to insert a protein coding sequence and a dominant selectable marker into a non-essential region of the VV genome. Recombinant viruses, selected on the basis of expression of the herpes simplex virus (HSV) thymidine kinase gene (tk), were shown to express in infected cells the model gene product, murine major histocompatibility complex (MHC) antigen H-2Kd, by cell-surface binding of antibody and by MHC-restricted recognition by cytotoxic T lymphocytes. Double recombinant VVs with insertions at two sites (in the VV tk gene and in the VV HindIII-F region) were constructed and shown to express influenza A/PR/8/34 haemagglutinin and H-2Kd antigen in addition to the HSV tk gene. The plasmids described allow the construction of recombinant VV expressing two genes of interest under the control of the same VV promoter. Such recombinant VVs can be used to study the interaction of immunologically important antigens simultaneously expressed.

Body mass index and blood pressure in Korean men and women: the Korean National Blood Pressure Survey.

AIMS AND METHODS: The association between body mass index (BMI) and blood pressure is well known in relatively obese populations. The purpose of the present study was to investigate the relationship between BMI and blood pressure in a lean population. Through cluster sampling, individuals aged > 30 years in 190 out of 154,082 districts were selected for study. Among 25,567 eligible individuals, measurements of blood pressure and BMI were made in 22,354. RESULTS: The BMI for males was 22.8 +/- 2.7 kg/m2 and for females was 23.4 +/- 3.2 kg/m2 (means +/- SD). Over a BMI range from 16 to 31 kg/m2 the relationships between BMI and systolic and diastolic blood pressure were almost linear. Over the BMI range 25-31 kg/m2 (overweight-to-obese) each BMI unit was associated with a difference of 1.0 mmHg in diastolic blood pressure. Over the BMI range 16-25 kg/m2 (normal-to-lean) each BMI unit was associated with a difference of 0.89 mmHg in diastolic blood pressure. CONCLUSION: We conclude that a strong association between BMI and blood pressure exists for lean as well as for obese subjects.

Fibrin clot lysis by tissue plasminogen activator (tPA) is impaired in plasma from pediatric patients undergoing orthotopic liver transplantation.

Large vessel thrombi can present life-threatening complications following orthotopic liver transplantation (OLT) in pediatric patients. We investigated the thrombolytic response to tissue plasminogen activator (tPA) of stored, pooled plasma (days 4-14 postoperatively) from 41 patients (mean age 4 years, 9 months) who underwent OLT at the Hospital for Sick Children, Toronto between 1986 and 1990. Trace-labeled fibrin clots were prepared by recalcifying 500-microliters aliquots of patient plasma spiked with 125I fibrinogen and then incubated at 37 degrees C in patient plasma in the presence or absence of tPA (0.1 or 0.3 mg/ml). At the end of the incubation period, the extent of clot lysis and concentrations of fibrinogen, plasminogen, and alpha 2 antiplasmin were determined. Pooled adult plasma was used as a control. Fibrin clot lysis in OLT plasma was significantly reduced compared with controls (P < 0.01). Initial concentrations of plasminogen were significantly reduced in OLT plasma. To determine if the low plasminogen levels limited the thrombolytic effect of tPA, we supplemented OLT plasma with purified plasminogen. Fibrin clots placed in OLT plasma containing adult levels of plasminogen showed a similar lytic response as adults. In summary, the reduced fibrinolytic response of OLT fibrin clots to tPA was due to low concentrations of plasminogen and corrected by plasminogen supplementation.

Expression of bovine leukaemia virus envelope gene by recombinant vaccinia viruses.

Recombinant vaccinia viruses (VV) containing the envelope gene of bovine leukaemia virus (BLV) were constructed. Three virus constructs were designed: VV-BLV1 which contained the open reading frame for envelope glycoprotein gp51 alone, under control of VVP7.5 promoter; VV-BLV2 and VV-BLV3 contained the entire gene (gp51 + gp30) coding sequence downstream of VP7.5 and the fowlpox virus early/late promoter (PFE/L) respectively. All three VV recombinants expressed envelope glycoproteins as determined by the agar gel diffusion assay. By immunofluorescence techniques it was shown that while VV-BLV2 and VV-BLV3 expressed envelope glycoprotein on the surface of virus-infected cells, VV-BLV1 failed to do so. Rabbits inoculated with VV-BLV1 failed to show an anti envelope glycoprotein antibody response, however, significant levels of antibodies against envelope glycoprotein were detected in sera from rabbits inoculated with VV-BLV2 and VV-BLV3.

Avian cytokines - the natural approach to therapeutics.

While the effective use of antibiotics for the control of human disease has saved countless lives and has increased life expectancy over the past few decades, there are concerns arising from their usage in livestock. The use of antibiotic feed additives in food production animals has been linked to the emergence in the food chain of multiple drug-resistant bacteria that appear impervious to even the most powerful antimicrobial agents. Furthermore, the use of chemical antimicrobials has led to concerns involving environmental contamination and unwanted residues in food products. The imminent banning of antibiotic usage in livestock feed has intensified the search for environmentally-friendly alternative methods to control disease. Cytokines, as natural mediators and regulators of the immune response, offer exciting new alternatives to conventional chemical-based therapeutics. The utilisation of cytokines is becoming more feasible, particularly in poultry, with the recent cloning of a number of avian cytokine genes. Chickens offer an attractive small animal model system with which to study the effectiveness of cytokine therapy in the control of disease in intensive livestock. In this report we will review the status of avian cytokines and focus on our recent studies involving the therapeutic potential of chicken interferon gamma (ChIFN-gamma) as a vaccine adjuvant and a growth promoter.

Stripping membranes at term: can it safely reduce the incidence of post-term pregnancies?

Membrane stripping has been used clinically for many years but has not been well studied. An investigation was undertaken to determine whether weekly membrane stripping beginning at 38 weeks could safely reduce post-term pregnancies. One hundred eighty patients with firm gestational dates were randomized to either a treatment or control group. Control subjects received a gentle cervicovaginal examination each week to assess Bishop scores, whereas the treatment group also underwent weekly stripping of membranes. Women who received treatment had earlier delivery (mean +/- SEM 8.60 +/- 0.74 versus 15.14 +/- 0.83 days; P less than .0001) and fewer post-term deliveries than those in the control group (three versus 14; P less than .004). The reduction of post-term pregnancies was most notable in nulliparous women with unfavorable Bishop scores. Complications were similar in both groups. Membrane stripping was safe and was associated with earlier delivery and a decreased incidence of post-term gestation.

Effect of heparin loading during congenital heart operation on thrombin generation and blood loss.

BACKGROUND: The heparin protocols used during cardiopulmonary bypass (CPB) in children undergoing surgical repair for congenital heart disease are extrapolated from adult data. Studies are needed that assess the optimal heparin dosing in these children, whose heparin clearance is increased compared with that in adults. METHODS: We assessed the effects of two commonly used doses of heparin in the prime solution at the start of CPB operation on plasma heparin levels, on thrombin production (thrombin-antithrombin III complexes, prothrombin fragment 1 + 2, D-dimer, and antithrombin III), and on the risk of hemorrhage. Before CPB, 48 children with congenital heart disease received heparin intravenously in a loading dose of 300 U/kg, followed by either 1 U/mL of heparin in the prime (low-dose group: 22 patients-acyanotic, 9; cyanotic, 13) or 3 U/mL of heparin in the prime (group: high-dose, 26 patients-acyanotic, 15; cyanotic, 11). RESULTS: In all patients, CPB resulted in the generation of thrombin. The duration of CPB was a significant covariate factor for heparin levels (p = 0.002), thrombin production (p < 0.001), and postoperative blood loss (p < 0.001). In the patients in the high-dose group, the total heparin dose and the plasma heparin levels were higher (p = 0.0005 and 0.005, respectively) and the D-dimer levels tended to be lower (p = 0.06). The postoperative blood loss was higher in the cyanotic patients (p = 0.02; both high-dose and low-dose groups), with 2 cyanotic patients (1 in low-dose group, 1 in high-dose group) requiring reoperation, one of whom subsequently died. The increased heparin dose had no significant effect on the rate or volume of postoperative blood loss. CONCLUSIONS: Increasing the heparin dose in the prime solution from 1 to 3 U/mL increased the plasma heparin levels and showed a trend toward reducing the postoperative laboratory values indicative of fibrinolysis. Thrombin generation during CPB and the incidence of postoperative hemorrhage were not significantly altered. Larger randomized trials are needed to determine the optimal heparin-dosing regimen in patients with congenital heart disease.

Venous thromboembolic events in pediatric patients. Diagnosis and management.

Venous thromboembolism is a rapidly increasing secondary complication in children being treated for serious, life-threatening, primary diseases. Most current management guidelines and recommendations for imaging techniques have been extrapolated from the results of trials in adults. This may be less than optimal for children as there are important differences. The purpose of this article is to summarize the information on venous thromboembolism in children, and offer some guidelines for diagnosis, prophylaxis, and therapeutic intervention based on the best available evidence.

A prime-boost vaccination strategy using naked DNA followed by recombinant porcine adenovirus protects pigs from classical swine fever.

Weaned pigs (6-week-old) and 7-day-old pre-weaned piglets were vaccinated with naked plasmid DNA expressing the gp55/E2 gene from classical swine fever virus (CSFV). Both groups of pigs were then given a booster dose of recombinant porcine adenovirus expressing the gp55 gene (rPAV-gp55). Following challenge with CSFV, 100% of weaned pigs and 75% pre-weaned piglets were protected from disease. Weaned pigs given a single dose of rPAV-gp55 were also protected, but showed a slight increase in temperature immediately post-challenge. However, weaned animals given a DNA prime before rPAV-gp55 showed no fluctuation in body temperature following challenge and no pathology in spleen or lymph nodes upon post-mortem. In addition, no CSFV could be re-isolated from the rPAV vaccinated group and from only one pig in the prime-boost group following challenge, suggesting that both vaccination regimes have the potential to reduce or prevent virus shedding following experimental challenge.