Identifying and quantifying heterogeneity in high content analysis: Application of heterogeneity indices to drug discovery

One of the greatest challenges in biomedical research, drug discovery and diagnostics is understanding how seemingly identical cells can respond differently to perturbagens including drugs for disease treatment. Although heterogeneity has become an accepted characteristic of a population of cells, in drug discovery it is not routinely evaluated or reported. The standard practice for cell-based, high content assays has been to assume a normal distribution and to report a well-to-well average value with a standard deviation. To address this important issue we sought to define a method that could be readily implemented to identify, quantify and characterize heterogeneity in cellular and small organism assays to guide decisions during drug discovery and experimental cell/tissue profiling. Our study revealed that heterogeneity can be effectively identified and quantified with three indices that indicate diversity, non-normality and percent outliers. The indices were evaluated using the induction and inhibition of STAT3 activation in five cell lines where the systems response including sample preparation and instrument performance were well characterized and controlled. These heterogeneity indices provide a standardized method that can easily be integrated into small and large scale screening or profiling projects to guide interpretation of the biology, as well as the development of therapeutics and diagnostics. Understanding the heterogeneity in the response to perturbagens will become a critical factor in designing strategies for the development of therapeutics including targeted polypharmacology. © 2014 Gough et al

Effects of Docosahexaenoic Acid Supplementation on Cortical Network Integrity in Medication-Free Children with Attention-Deficit/Hyperactivity Disorder: A Preliminary Multimodal Neuroimaging Trial

Abstract: Children with attention deficit/hyperactivity disorder (ADHD) exhibit blood docosahexaenoic acid (DHA) deficits and cortical network pathology. This neuroimaging study investigated the effects of DHA supplementation on cortical attention network integrity in medication-free children with ADHD. Children (mean age 9.6 years, n=30) with ADHD were randomized to DHA (1,200 mg/d) or placebo for 10 weeks. Blood DHA levels and ADHD symptom severity ratings were obtained from all participants (n=30). Cortical network integrity was evaluated in a subset of patients (n=20) using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). Erythrocyte DHA levels increased significantly in patients receiving DHA (+60%, p≤0.0001) but not placebo (-4%, p=0.77). There were no group differences in baseline-endpoint change in ADHD symptom severity scores, sustained attention performance, or voxelwise cortical activation patterns during performance of a sustained attention task. In the region-of-interest (ROI) analysis, patients treated with DHA but not placebo exhibited significant endpoint reductions in left amygdala activation. At study endpoint, but not at baseline, DHA-treated patients exhibited significantly greater event-related functional connectivity between the pregenual and subgenual anterior cingulate cortex and regions within the cortical attention network including the inferior parietal lobe and dorsolateral prefrontal cortex compared with placebo. Trends with large effect sizes for reductions in medial and radial diffusivity in the left corpus callosum were observed in DHA-treated patients. These preliminary findings suggest that DHA supplementation may be associated with subtle changes in cortical attention networks of medication-free children with ADHD which warrant additional investigation in a larger patient sample

Effects of Docosahexaenoic Acid Supplementation on Cortical Network Integrity in Medication-Free Children with Attention-Deficit/Hyperactivity Disorder: A Preliminary Multimodal Neuroimaging Trial

Children with attention deficit/hyperactivity disorder (ADHD) exhibit blood docosahexaenoic acid (DHA) deficits and cortical network pathology. This neuroimaging study investigated the effects of DHA supplementation on cortical attention network integrity in medication-free children with ADHD. Children (mean age 9.6 years, n=30) with ADHD were randomized to DHA (1,200 mg/d) or placebo for 10 weeks. Blood DHA levels and ADHD symptom severity ratings were obtained from all participants (n=30). Cortical network integrity was evaluated in a subset of patients (n=20) using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). Erythrocyte DHA levels increased significantly in patients receiving DHA (+60%, p≤0.0001) but not placebo (-4%, p=0.77). There were no group differences in baseline-endpoint change in ADHD symptom severity scores, sustained attention performance, or voxelwise cortical activation patterns during performance of a sustained attention task. In the region-of-interest (ROI) analysis, patients treated with DHA but not placebo exhibited significant endpoint reductions in left amygdala activation. At study endpoint, but not at baseline, DHA-treated patients exhibited significantly greater event-related functional connectivity between the pregenual and subgenual anterior cingulate cortex and regions within the cortical attention network including the inferior parietal lobe and dorsolateral prefrontal cortex compared with placebo. Trends with large effect sizes for reductions in medial and radial diffusivity in the left corpus callosum were observed in DHA-treated patients. These preliminary findings suggest that DHA supplementation may be associated with subtle changes in cortical attention networks of medication-free children with ADHD which warrant additional investigation in a larger patient sample

Leptin Regulates Energy Balance and Motivation Through Action at Distinct Neural Circuits

Overconsumption of calorically dense foods contributes substantially to the current obesity epidemic. The adiposity hormone leptin has been identified as a potential modulator of reward-induced feeding. The current study asked whether leptin signaling within the lateral hypothalamus (LH) and midbrain is involved in effort-based responding for food rewards and/or the modulation of mesolimbic dopamine. The contribution of endogenous leptin signaling for food motivation and mesolimbic dopamine tone was examined after viral-mediated reduction of the leptin receptor within LH and midbrain neurons in male rats. Knockdown of leptin receptors selectively in the LH caused increased body weight, caloric consumption, and body fat in rats maintained on a calorically dense diet. Knockdown of leptin receptors selectively in midbrain augmented progressive ratio responding for sucrose and restored high-fat, diet-induced suppression of dopamine content in the nucleus accumbens. In summary, endogenous leptin signaling in the hypothalamus restrains the overconsumption of calorically dense foods and the consequent increase in body mass, whereas leptin action in the midbrain regulates effort-based responding for food rewards and mesolimbic dopamine tone. These data highlight the ability of leptin to regulate overconsumption of palatable foods and food motivation through pathways that mediate energy homeostasis and reward, respectively