Directionality of Epistasis in a Murine Intercross Population

Directional epistasis describes a situation in which epistasis consistently increases or decreases the effect of allele substitutions, thereby affecting the amount of additive genetic variance available for selection in a given direction. This study applies a recent parameterization of directionality of epistasis to empirical data. Data stems from a QTL mapping study on an intercross between inbred mouse (Mus musculus) strains LG/J and SM/J, originally selected for large and small body mass, respectively. Results show a negative average directionality of epistasis for body-composition traits, predicting a reduction in additive allelic effects and in the response to selection for increased size. Focusing on average modification of additive effect of single loci, we find a more complex picture, whereby the effects of some loci are enhanced consistently across backgrounds, while effects of other loci are decreased, potentially contributing to either enhancement or reduction of allelic effects when selection acts at single loci. We demonstrate and discuss how the interpretation of the overall measurement of directionality depends on the complexity of the genotype–phenotype map. The measure of directionality changes with the power of scale in a predictable way; however, its expected effect with respect to the modification of additive genetic effects remains constant.EPISTASIS is present when the effect of a genetic substitution depends on the genotypes at other loci. At the population level, this means that average allelic effects change as allele frequencies at other loci change, and thus that gene effects can evolve. The evolutionary significance of epistasis has been recognized mainly in relation to the allele-frequency changes that are caused by genetic drift (e.g., Goodnight 1987, 1988, 1995; Cheverud and Routman 1996; Barton and Turelli 2004; De Brito et al. 2005; Turelli and Barton 2006), whereas the epistatic effects under directional selection have been treated only recently (e.g., Carter et al. 2005; Weinreich et al. 2005; Carlborg et al. 2006; Hansen et al. 2006; Yukilevich et al. 2008). Technically, the effects of epistatic interaction can be considered as having two aspects: the architecture itself (i.e., the existence of a nonadditive component, the so-called functional aspect, see below), and the effect of allele frequency on genetic variance (i.e., the statistical aspect). An additional consideration is crucial for the response to selection of a given trait, namely that the response is generated by the joint action of many epistatic interactions. Each of the interactions can either enhance or diminish the additive genetic effect in any specific phenotypic dimension. Their composite effect depends on the pattern, i.e., whether the effects accumulate or cancel each other out (Hansen and Wagner 2001a,b; Carter et al. 2005; Hansen et al. 2006). In the following we provide a brief general account of epistasis and then focus on the effect of its composite pattern, the empirical assessment of which is the goal of this study.The traditional population-genetic approach to selection response initially emphasized additive genetic variance and treated any variance unexplained by the additive effects, including variance due to interactions within or between loci, as residual variance (Fisher 1918). Later this model was extended to account for epistasis (Cockerham 1954, Kempthorne 1954). The interaction component of this residual variance is dependent on population allele frequencies at the interacting loci. Starting with nonadditive effects within a single locus (dominance), Falconer (1960) described the effect of allele frequencies on the statistical measure of average allelic effect. Cheverud and Routman (1995) explored the analogous effect at the two-locus level, leading to distinction between allele-frequency-dependent statistical epistasis (contributing to epistatic variance) on population level, and allele-frequency-independent physiological (or functional) epistasis on the individual level, which contributes to all the genetic variance components, i.e.,, additive, dominance, and epistatic. Thus while physiological epistasis describes the genetic architecture of a given phenotype defining the potential for epistatic effects, statistical epistasis describes the realization of individual-level epistatic effects in terms of allele-frequency-dependent genetic variance components. Several authors have worked out tools to estimate gene interaction effects at the individual level independently of the allele frequencies to distinguish between the physiological and statistical epistasis (Cheverud and Routman 1995; Wagner et al. 1998; Hansen and Wagner 2001a; Barton and Turelli 2004; Yang 2004; Zeng et al. 2005; Wang and Zeng 2006). These methods have been recently generalized in a common framework for measuring epistasis and translating between the population and individual levels (NOIA: Alvarez-Castro and Carlborg 2007; Alvarez-Castro et al. 2008; see Le Rouzic 2008 for R software package). An understanding of the pattern of epistatic architecture enables prediction of its effects at any given set of allele frequencies.The original physiological epistasis has often referred to isolated pairwise interactions. The genetic basis of a complex trait is affected by more than two interacting loci; thus the trait''s genetic variance is affected by the combination of these interaction effects. Effects at the individual loci can add up, or cancel out. For example, when the alleles at background loci become fixed (e.g., due to a bottleneck), previously background-dependent genetic effects at loci A and B can become additive effects of the same or of the opposite sign. Depending on the sign and size of their effects, the two allele substitutions at loci A and B therefore add up to increase, decrease, or have no overall effect on additive genetic variance. Hansen and Wagner (2001a) introduced the notion of directionality of epistasis to emphasize the importance of the pattern of epistatic architecture for the system''s evolvability. Directionality measures the consistency of epistatic effects on additive variance for a specific locus and trait across the genome, given a defined reference genotype. It describes whether epistasis tends to enhance or diminish the additive effects of interacting loci on a trait in a specified phenotypic direction. The population-dynamic studies analyzing effects of the epistatic pattern show that the directionality of epistasis can be a major determinant of evolution on time scales beyond a few generations (Hermisson et al. 2003; Carter et al. 2005; Hansen et al. 2006; Yukilevich et al. 2008; Alvarez-Castro et al. 2009; Fierst and Hansen 2010). Averaged across interactions, positive directional epistasis increases additive variance and the response to positive selection relative to that predicted by the additive genetic effects alone, while negative directional epistasis tends to decrease the response to selection in that same phenotypic direction. An absence of epistatic directionality occurs when positive and negative directional epistatic effects cancel out on average or, trivially, from the absence of epistasis. Thus directionality describes the local, population-specific curvature of the genotype–phenotype map (Figure 1).Open in a separate windowFigure 1.—Directionality of epistasis describes the local curvature of the genotype–phenotype map. The genotypic values of the trait of interest in the two parental inbred populations and in an intercross are plotted on y-axis. Given a defined direction on a trait axis and a reference point for measurement of genetic effects, the directionality () describes whether the epistasis increases or decreases the effect of allelic substitutions relative to the value predicted by additive effects alone. The extrapolation of the curvature beyond the local effects requires the knowledge of higher-order epistatic effects; however, the local effects can be calculated for different reference points and different phenotypic directions (see Hansen and Wagner 2001a,b).Aspects of epistatic directionality have been addressed previously with respect to the effect on fitness (reviewed in Phillips et al. 2000), with focus on the synergistic epistasis for deleterious effect enhancement (e.g., Kondrashov 1988; Charlesworth 1990; Hansen and Wagner 2001b). However, the empirical study of overall directionality of epistasis, and its measurement in morphological or physiological traits, is still lacking (Hansen 2006). Implicit indications from empirical studies are ambiguous (see examples in Carter et al. 2005). Here, we present an assessment of directionality of two-way epistasis between QTL in an intercross population of laboratory mice, paying special attention to scale effects.     

Stereotypes Possess Heterogeneous Directionality: A Theoretical and Empirical Exploration of Stereotype Structure and Content

We advance a theory-driven approach to stereotype structure, informed by connectionist theories of cognition. Whereas traditional models define or tacitly assume that stereotypes possess inherently Group → Attribute activation directionality (e.g., Black activates criminal), our model predicts heterogeneous stereotype directionality. Alongside the classically studied Group → Attribute stereotypes, some stereotypes should be bidirectional (i.e., Group ⇄ Attribute) and others should have Attribute → Group unidirectionality (e.g., fashionable activates gay). We tested this prediction in several large-scale studies with human participants (N_Combined = 4,817), assessing stereotypic inferences among various groups and attributes. Supporting predictions, we found heterogeneous directionality both among the stereotype links related to a given social group and also between the links of different social groups. These efforts yield rich datasets that map the networks of stereotype links related to several social groups. We make these datasets publicly available, enabling other researchers to explore a number of questions related to stereotypes and stereotyping. Stereotype directionality is an understudied feature of stereotypes and stereotyping with widespread implications for the development, measurement, maintenance, expression, and change of stereotypes, stereotyping, prejudice, and discrimination.     

The Associations between Anthropometric Indices and Obstructive Sleep Apnea in a Korean Population

Background

Obesity is a major risk factor for the development of obstructive sleep apnea (OSA). Although clinical and epidemiological studies have shown that OSA and obesity are strongly associated, few Asian studies have examined the associations between anthropometric obesity indices and OSA, especially in the Korean population. The purpose of this study was to evaluate the influence of anthropometric obesity indices on OSA in a Korean population.

Methods

Anthropometric indices, including neck circumference, waist circumference, and body mass index, were assessed in 383 consecutive subjects with suspected OSA.

Results

Of the 383 subjects assessed, 316 (82.5%) were diagnosed with OSA. Neck circumference (r = 0.518), waist circumference (r = 0.570), and body mass index (r = 0.512) were correlated with the apnea-hypopnea index (p<0.001, for all). After adjusting for age, sex, alcohol consumption, and smoking, a logistic regression model showed that neck circumference [odds ratio (OR), 1.414; p<0.001)], waist circumference (OR, 1.114; p<0.001), and body mass index (OR, 1.364; p<0.001) were associated with OSA. The linear regression model showed that neck circumference (β = 3.748, p<0.001), waist circumference (β = 1.272, p<0.001), and body mass index (β = 3.082, p<0.001) were associated with apnea-hypopnea index. The cut-off values for predicting OSA were determined as 34.5 cm for neck circumference, 76.5 cm for waist circumference, and 23.05 kg/m² for body mass index for females, and 38.75 cm for neck circumference, 88.5 cm for waist circumference, and 24.95 kg/m² for body mass index for males.

Conclusion

Increased anthropometric indices were significantly associated with the presence and severity of OSA in a Korean population. In addition, this study demonstrated the cut-off values for body mass index, waist circumference, and neck circumference for increased OSA risk.     

Associations between Disease Awareness and Health-Related Quality of Life in a Multi-Ethnic Asian Population

Background

Health related quality of life (HRQoL) is an important dimension of individuals'' well-being, and especially in chronic diseases like diabetes and hypertension. The objective of this study was to evaluate the contributions of disease process, comorbidities, medication or awareness of the disease to HRQoL in diabetes mellitus, hypertension and dyslipidemia.

Methods

This was a cross-sectional study of 3514 respondents from the general community in Singapore, assessed for HRQoL, disease and comorbid conditions through self-report, clinical and laboratory investigations. HRQoL was assessed using SF-36 health survey version 2. For each condition, participants were categorized as having 1) no disease, 2) undiagnosed, 3) diagnosed, not taking medication, and 4) diagnosed, taking medication. Analysis used one-way ANOVA and multiple linear regression.

Results

Diagnosed disease was associated with lower physical health component summary (PCS) scores across all three conditions. After adjustment for comorbidities, this association remained significant only for those not on medication in diabetes (−2.7±1.2 points, p = 0.03) and dyslipidemia (−1.3±0.4 points, p = 0.003). Diagnosed hypertension (no medication −2.6±0.9 points, p = 0.002; medication −1.4±0.5 points, p = 0.004) and dyslipidemia (no medication −0.9±0.4 points, p = 0.03; medication −1.9±0.5 points, p<0.001) were associated with lower mental health component summary (MCS) scores. Undiagnosed disease was associated with higher MCS in diabetes (2.4±1.0 points, p = 0.01) and dyslipidemia (0.8±0.4 points, p = 0.045), and PCS in hypertension (1.2±0.4 points, p = 0.004).

Conclusions

Disease awareness was associated with lower HRQoL across the diseases studied, with PCS associations partially mediated by comorbidities. Equally importantly, undiagnosed disease was not associated with HRQoL deficits, which may partly explain why these individuals do not seek medical care.     

Prevalence of the Metabolic Syndrome in a Bulgarian Female Population Referred for Bone Density Testing

Objective: To investigate the prevalence of the metabolic syndrome in Bulgarian women referred for bone density screening. Research Methods and Procedures: This was a cross‐sectional clinical study. Subjects were 444 consecutive 30‐ to 75‐year‐old Bulgarian women recruited from the outpatients referred for bone density testing (mean age, 52.67 ± 15.19 years; mean BMI, 26.10 ± 5.71 kg/m²). Height (centimeters), weight (kilograms), and blood pressure were measured. BMI and waist‐to‐hip ratio were calculated. Fasting plasma glucose, blood lipids, and immunoreactive insulinemia (Bayer Corp.‐Diagnostics Div., Tarrytown, NY) were determined. Body composition was analyzed by bioimpedance on a leg‐to‐leg analyser (Tanita TBF‐215; Tanita Corporation, Tokyo, Japan). Results: Of all women, 56.76% had a BMI > 25 kg/m², 45.95% had a waist circumference > 88 cm, and 64.64% had a waist‐to‐hip ratio > 0.8; 59.90% had hypertension; 4.05% had fasting plasma glucose > 7.0 mM, and 42.79% had fasting morning immunoreactive insulinemia = 16 UI/liter; 23.65% had hypercholesterolemia; and 26.35% had hypertriglyceridemia. The prevalence of the metabolic syndrome in this sample, as defined by the National Cholesterol and Education Program‐Adult Treatment Panel III, was 34.91%, and by the modified World Health Organization definition was 37.16%. Discussion: We concluded that Bulgarian women 30 to 75 years old referred for bone density testing have a high prevalence of the metabolic syndrome. Therefore, large‐scale prevention programs are needed in this field.     

Associations of ABHD2 Genetic Variations with Risks for Chronic Obstructive Pulmonary Disease in a Chinese Han Population

The human α/β hydrolase domain-containing protein 2 gene (ABHD2) plays a critical role in pulmonary emphysema, a major subset of the clinical entity known as chronic obstructive pulmonary disease (COPD). Here, we evaluated genetic variation in the ABHD2 gene in a Chinese Han population of 286 COPD patients and 326 control subjects. The rs12442260 CT/CC genotype was associated with COPD (P < 0.001) under a dominant model. In the former-smoker group, the rs12442260 TT genotype was associated with a decreased risk of developing COPD after adjusting for age, gender and pack-years (P = 0.012). Rs12442260 was also associated with pre-FEV1 (the predicted bronchodilator forced expiratory volume in the first second) in controls (P = 0.027), but with FEV1/ forced vital capacity (FVC) ratios only in COPD patients (P = 0.012) under a dominant model. Results from the current study suggest that ABHD2 gene polymorphisms contribute to COPD susceptibility in the Chinese Han population.     

HPV Testing by cobas HPV Test in a Population from Catalonia

Background

HPV testing in cervical cancer screening has been proposed as an alternative or complementary to cytology in women older than 30 years. However, adequate clinical sensitivity and specificity are crucial for a new test to be implemented. Hybrid Capture 2 (HC2) has proved good clinical performance in selecting women at risk for high-grade intraepithelial lesions with a high sensitivity and specificity. cobas HPV Test has been recently launched and its performance in different clinical settings needs to be determined.

Objectives

The aim of this study was to evaluate the cobas HPV Test for the detection of cervical HPV infection in a population of women in Catalonia (Spain) using HC2 as a reference.

Materials and Methods

Cervical liquid cytology samples from 958 women have been studied. Sensitivity was analyzed in 60 samples from patients with a high-grade intraepithelial lesion (≥CIN2) on histology and specificity was determined in 898 samples from women with no ≥CIN2. All cases had HC2 and cobas HPV Test performed. Statistical analyses of sensitivity, specificity and comparison between HC2 and cobas HPV Test by a non-inferiority test were applied.

Results

Sensitivity of HC2 and cobas HPV Test for detecting ≥CIN2 proved identical (98.3%) while specificity was 85.3% and 86.2% respectively. The non-inferiority test demonstrated that cobas HPV Test surpassed 90% sensitivity and 98% specificity of HC2.

Conclusion

The cobas HPV Test results fulfilled sensitivity and specificity requirements for HPV based cervical cancer screening and for the triage of minor cytological abnormalities, allowing its introduction in clinical settings.     

The Heterogeneous HLA Genetic Makeup of the Swiss Population

THIS STUDY AIMS AT INVESTIGATING THE HLA MOLECULAR VARIATION ACROSS SWITZERLAND IN ORDER TO DETERMINE POSSIBLE REGIONAL DIFFERENCES, WHICH WOULD BE HIGHLY RELEVANT TO SEVERAL PURPOSES: optimizing donor recruitment strategies in hematopoietic stem cell transplantation (HSCT), providing reliable reference data in HLA and disease association studies, and understanding the population genetic background(s) of this culturally heterogeneous country. HLA molecular data of more than 20,000 HSCT donors from 9-13 recruitment centers of the whole country were analyzed. Allele and haplotype frequencies were estimated by using new computer tools adapted to the heterogeneity and ambiguity of the data. Non-parametric and resampling statistical tests were performed to assess Hardy-Weinberg equilibrium, selective neutrality and linkage disequilibrium among different loci, both in each recruitment center and in the whole national registry. Genetic variation was explored through genetic distance and hierarchical analysis of variance taking into account both geographic and linguistic subdivisions in Switzerland. The results indicate a heterogeneous genetic makeup of the Swiss population: first, allele frequencies estimated on the whole national registry strongly deviate from Hardy-Weinberg equilibrium, by contrast with the results obtained for individual centers; second, a pronounced differentiation is observed for Ticino, Graubünden, and, to a lesser extent, Wallis, suggesting that the Alps represent(ed) a barrier to gene flow; finally, although cultural (linguistic) boundaries do not represent a main genetic differentiation factor in Switzerland, the genetic relatedness between population from south-eastern Switzerland and Italy agrees with historical and linguistic data. Overall, this study justifies the maintenance of a decentralized donor recruitment structure in Switzerland allowing increasing the genetic diversity of the national-and hence global-donor registry. It also indicates that HLA data of local donor recruitment centers can be used as reference data in both epidemiological and population genetic studies focusing on the genetic history of present European populations.     

Mosquito Population Regulation and Larval Source Management in Heterogeneous Environments

An important question for mosquito population dynamics, mosquito-borne pathogen transmission and vector control is how mosquito populations are regulated. Here we develop simple models with heterogeneity in egg laying patterns and in the responses of larval populations to crowding in aquatic habitats. We use the models to evaluate how such heterogeneity affects mosquito population regulation and the effects of larval source management (LSM). We revisit the notion of a carrying capacity and show how heterogeneity changes our understanding of density dependence and the outcome of LSM. Crowding in and productivity of aquatic habitats is highly uneven unless egg-laying distributions are fine-tuned to match the distribution of habitats’ carrying capacities. LSM reduces mosquito population density linearly with coverage if adult mosquitoes avoid laying eggs in treated habitats, but quadratically if eggs are laid in treated habitats and the effort is therefore wasted (i.e., treating 50% of habitat reduces mosquito density by approximately 75%). Unsurprisingly, targeting (i.e. treating a subset of the most productive pools) gives much larger reductions for similar coverage, but with poor targeting, increasing coverage could increase adult mosquito population densities if eggs are laid in higher capacity habitats. Our analysis suggests that, in some contexts, LSM models that accounts for heterogeneity in production of adult mosquitoes provide theoretical support for pursuing mosquito-borne disease prevention through strategic and repeated application of modern larvicides.     

Directionality of the tympanal vibrations in a cicada: a biophysical analysis

1. Laser vibrometry and acoustic measurements were used to study the biophysics of directional hearing in males and females of a cicada, in which most of the male tympanum is covered by thick, water filled tissue “pads”. 2. In females, the tympanal vibrations are very dependent on the direction of sound incidence in the entire frequency range 1–20 kHz, and especially at the main frequencies of the calling song (3–7 kHz). At frequencies up to 10 kHz, the directionality disappears if the contralateral tympanum, metathoracic spiracle, and folded membrane are blocked with Vaseline. This suggests some pressure-difference receiver properties in the ear. 3. In males, the tympanal vibrations depend on the direction of sound incidence only within narrow frequency bands (around 1.8 kHz and at 6–7 kHz). At frequencies above 10–12 kHz, the directionality appears to be determined by diffraction, and the ear seems to work as a pressure receiver. The peak in directionality at 6–7 kHz disappears when the contralateral timbal, but not the tympanum, is covered. Covering the thin ventral abdominal wall causes the peak around 1.8 kHz to disappear. 4. Most observed tympanal directionalities, except around 1.8 kHz in males, are well predicted from measured transmissions of sound through the body and measured values of sound amplitude and phase at the ears at various directions of sound incidence. Accepted: 18 October 1996     

Directionality of a one way movement detector in the crayfishCherax destructor

Summary Directionality curves for vertical one way movement detector neurons in the crayfish were obtained during whole animal oscillation around continuously varying horizontal axes. Results are presented in detail for one easily monitored unit, M.D.I. In a fresh animal, maximum sensitivity was shown to rotation in the rolling plane. In an adapted animal, the maximum sensitivity, was shifted by 45° and the directionality curve became markedly asymmetrical. Right and left adapted M.D.I cells have axes for maximum response 90° apart. The results can be explained simply by a reduction in excitability of input cells coding the set of orthogonal components of a rotation at 45° to the pitch and roll set of orthogonal components.     

The Performance of Mixture Models in Heterogeneous Closed Population Capture–Recapture

Summary .   Dorazio and Royle (2003, Biometrics 59, 351–364) investigated the behavior of three mixture models for closed population capture–recapture analysis in the presence of individual heterogeneity of capture probability. Their simulations were from the beta-binomial distribution, with analyses from the beta-binomial, the logit-normal, and the finite mixture (latent class) models. In this response, simulations from many different distributions give a broader picture of the relative value of the beta-binomial and the finite mixture models, and provide some preliminary insights into the situations in which these models are useful.     

Directionality of acoustic orientation in flying crickets

Summary Abdominal flexions associated with flight steering were measured in tethered flyingTeleogryllus oceanicus stimulated with a model of conspecific calling song presented at various intensities and from many directions.Flexions increased in size with stimulus intensity until a plateau level was reached. Flexion amplitude was then approximately constant over a range of 20–30 dB, and decreased at still higher intensities (Figs. 2, 3). The shape of this intensity function results from binaural processing; in unilaterally deafened crickets flexion amplitude increased monotonically with stimulus intensity (Fig. 4).Abdominal flexions were graded with respect to sound location; they were larger for laterally placed sound sources and smaller for sound sources near the midline (Figs. 5, 6).A model for the specification of flight steering movements is presented which accounts for our findings (Fig. 7).     

Spike Triggered Hormone Secretion in Vasopressin Cells; a Model Investigation of Mechanism and Heterogeneous Population Function

Vasopressin neurons generate distinctive phasic patterned spike activity in response to elevated extracellular osmotic pressure. These spikes are generated in the cell body and are conducted down the axon to the axonal terminals where they trigger Ca²⁺ entry and subsequent exocytosis of hormone-containing vesicles and secretion of vasopressin. This mechanism is highly non-linear, subject to both frequency facilitation and fatigue, such that the rate of secretion depends on both the rate and patterning of the spike activity. Here we used computational modelling to investigate this relationship and how it shapes the overall response of the neuronal population. We generated a concise single compartment model of the secretion mechanism, fitted to experimentally observed profiles of facilitation and fatigue, and based on representations of the hypothesised underlying mechanisms. These mechanisms include spike broadening, Ca²⁺ channel inactivation, a Ca²⁺ sensitive K⁺ current, and releasable and reserve pools of vesicles. We coupled the secretion model to an existing integrate-and-fire based spiking model in order to study the secretion response to increasing synaptic input, and compared phasic and non-phasic spiking models to assess the functional value of the phasic spiking pattern. The secretory response of individual phasic cells is very non-linear, but the response of a heterogeneous population of phasic cells shows a much more linear response to increasing input, matching the linear response we observe experimentally, though in this respect, phasic cells have no apparent advantage over non-phasic cells. Another challenge for the cells is maintaining this linear response during chronic stimulation, and we show that the activity-dependent fatigue mechanism has a potentially useful function in helping to maintain secretion despite depletion of stores. Without this mechanism, secretion in response to a steady stimulus declines as the stored content declines.     

CCAST: A Model-Based Gating Strategy to Isolate Homogeneous Subpopulations in a Heterogeneous Population of Single Cells

A model-based gating strategy is developed for sorting cells and analyzing populations of single cells. The strategy, named CCAST, for Clustering, Classification and Sorting Tree, identifies a gating strategy for isolating homogeneous subpopulations from a heterogeneous population of single cells using a data-derived decision tree representation that can be applied to cell sorting. Because CCAST does not rely on expert knowledge, it removes human bias and variability when determining the gating strategy. It combines any clustering algorithm with silhouette measures to identify underlying homogeneous subpopulations, then applies recursive partitioning techniques to generate a decision tree that defines the gating strategy. CCAST produces an optimal strategy for cell sorting by automating the selection of gating markers, the corresponding gating thresholds and gating sequence; all of these parameters are typically manually defined. Even though CCAST is optimized for cell sorting, it can be applied for the identification and analysis of homogeneous subpopulations among heterogeneous single cell data. We apply CCAST on single cell data from both breast cancer cell lines and normal human bone marrow. On the SUM159 breast cancer cell line data, CCAST indicates at least five distinct cell states based on two surface markers (CD24 and EPCAM) and provides a gating sorting strategy that produces more homogeneous subpopulations than previously reported. When applied to normal bone marrow data, CCAST reveals an efficient strategy for gating T-cells without prior knowledge of the major T-cell subtypes and the markers that best define them. On the normal bone marrow data, CCAST also reveals two major mature B-cell subtypes, namely CD123+ and CD123- cells, which were not revealed by manual gating but show distinct intracellular signaling responses. More generally, the CCAST framework could be used on other biological and non-biological high dimensional data types that are mixtures of unknown homogeneous subpopulations.     

Associations of Lifestyle Factors,Disease History and Awareness with Health-Related Quality of Life in a Thai Population

Background

The impact of the presence and awareness of individual health states on quality of life (HRQoL) is often documented. However, the impacts of different health states have rarely been compared amongst each other, whilst quality of life data from Asia are relatively sparse. We examined and compared the effects of different health states on quality of life in a Thai population.

Methods

In 2008–2009, 5,915 corporate employees were invited to participate in a survey where HRQoL was measured by the Short Form 36 (SF-36) questionnaire. The adjusted mean SF-36 scores were calculated for each self-reported illness, number of chronic conditions, lifestyle factors and awareness of diabetes and hypertension. The effect sizes (ES) were compared using Cohen''s d.

Results

The response rate was 82% and 4,683 (79.1%) had complete data available for analysis. Physical and Mental Component Summary (PCS and MCS) scores decreased as the number of chronic conditions increased monotonically (p<0.0001). Diabetes and hypertension negatively influenced PCS (mean score differences −0.6 and −1.5, p<0.001 respectively) but not MCS, whereas awareness of diabetes and hypertension negatively influenced MCS (−2.9 and −1.6, p<0.005 respectively) but not PCS. Arthritis had the largest ES on PCS (−0.37), while awareness of diabetes had the largest ES on MCS (−0.36). CVD moderately affected PCS and MCS (ES −0.34 and −0.27 respectively). Obesity had a negative effect on PCS (ES −0.27). Exercise positively affected PCS and MCS (ES +0.08 and +0.21 (p<0.01) respectively).

Conclusion

Health promotion to reduce the prevalence of chronic diseases is important to improve the quality of life in Asian populations. Physical activity is an important part of such programs. Awareness of diseases may have greater impacts on mental health than having the disease itself. This has implications for the evaluation of the cost-benefit of screening and labeling of individuals with pre-disease states.     

Impact of Small Groups with Heterogeneous Preference on Behavioral Evolution in Population Evacuation

Up to now, there have been a great number of mechanisms to explain the individual behavior and population traits, which seem of particular significance in evolutionary biology and social behavior analysis. Among them, small groups and heterogeneity are two useful frameworks to the above issue. However, vast majority of existing works separately consider both scenarios, which is inconsistent with realistic cases in our life. Here we propose the evolutionary games of heterogeneous small groups (namely, different small groups possess different preferences to dilemma) to study the collective behavior in population evacuation. Importantly, players usually face completely different dilemmas inside and outside the small groups. By means of numerous computation simulations, it is unveiled that the ratio of players in one certain small group directly decides the final behavior of the whole population. Moreover, it can also be concluded that heterogeneous degree of preference for different small groups plays a key role in the behavior traits of the system, which may validate some realistic social observations. The proposed framework is thus universally applicable and may shed new light into the solution of social dilemmas.