Discovery of an intravenous hepatoselective glucokinase activator for the treatment of inpatient hyperglycemia

Glucokinase (hexokinase IV) continues to be a compelling target for the treatment of type 2 diabetes given the wealth of supporting human genetics data and numerous reports of robust clinical glucose lowering in patients treated with small molecule allosteric activators. Recent work has demonstrated the ability of hepatoselective activators to deliver glucose lowering efficacy with minimal risk of hypoglycemia. While orally administered agents require a considerable degree of passive permeability to promote suitable exposures, there is no such restriction on intravenously delivered drugs. Therefore, minimization of membrane diffusion in the context of an intravenously agent should ensure optimal hepatic targeting and therapeutic index. This work details the identification a hepatoselective GKA exhibiting the aforementioned properties.     

A Metabolomics-driven Elucidation of the Anti-obesity Mechanisms of Xanthohumol

Mild, mitochondrial uncoupling increases energy expenditure and can reduce the generation of reactive oxygen species (ROS). Activation of cellular, adaptive stress response pathways can result in an enhanced capacity to reduce oxidative damage. Together, these strategies target energy imbalance and oxidative stress, both underlying factors of obesity and related conditions such as type 2 diabetes. Here we describe a metabolomics-driven effort to uncover the anti-obesity mechanism(s) of xanthohumol (XN), a prenylated flavonoid from hops. Metabolomics analysis of fasting plasma from obese, Zucker rats treated with XN revealed decreases in products of dysfunctional fatty acid oxidation and ROS, prompting us to explore the effects of XN on muscle cell bioenergetics. At low micromolar concentrations, XN acutely increased uncoupled respiration in several different cell types, including myocytes. Tetrahydroxanthohumol also increased respiration, suggesting electrophilicity did not play a role. At higher concentrations, XN inhibited respiration in a ROS-dependent manner. In myocytes, time course metabolomics revealed acute activation of glutathione recycling and long term induction of glutathione synthesis as well as several other changes indicative of short term elevated cellular stress and a concerted adaptive response. Based on these findings, we hypothesize that XN may ameliorate metabolic syndrome, at least in part, through mitochondrial uncoupling and stress response induction. In addition, time course metabolomics appears to be an effective strategy for uncovering metabolic events that occur during a stress response.     

Comparison of the Genome Sequences of “Candidatus Portiera aleyrodidarum” Primary Endosymbionts of the Whitefly Bemisia tabaci B and Q Biotypes

“Candidatus Portiera aleyrodidarum” is the primary endosymbiont of whiteflies. We report two complete genome sequences of this bacterium from the worldwide invasive B and Q biotypes of the whitefly Bemisia tabaci. Differences in the two genome sequences may add insights into the complex differences in the biology of both biotypes.     

Conformational Studies of Dextran [α-(1⇒6)-D-Glucan]

Abstract

A theoretical conformational study of dextran, a (l?6)-linked α-D-glucan polysaccharide, has been made to allow an explicit comparison with earlier results on pustulan, the corresponding (1 ?6)-linked β-D-glucan. The nonbonded, torsional and hydrogen bond contributions to potential energy were calculated as a function of rotational angles φ, ψ, and ω The (φ, ψ, ω)-space of the disaccharide and of helices contain many local energy minima with very small energy differences. A comparison of (1?6)-α-D-glucans with (1?6)-β-D-glucans indicates significant differences in conformational behavior. Specifically, our results shed light on the fact that dextran does not gel, whereas pustulan does. The difference in tendency to gel may be related to the fact that dextran has no particularly favored conformations with structural regularity whereas pustulan does.     

Wavelength dependence of patman equilibration dynamics in phosphatidylcholine bilayers

Assessment of the equilibration kinetics of Patman at the edges of its emission spectra provided additional insights about membrane properties beyond those obtained from end-point fluorescence measurements. Upon introduction of the probe to aqueous suspensions of liposomes, the emission intensity slowly increased about 10-fold (t_½ = ~ 100 s). The rate of equilibration depended on emission wavelength, and was usually faster at 500 than at 435 nm. However, this trend was reversed for equilibration with lipids at their phase transition temperature. The apparent rotational motion of the dye also differed between the long and short emission wavelengths but did not display the slow equilibration time dependence observed with intensity measurements. These results suggested that slow equilibration reflects relaxation of the immediate membrane microenvironment around the probe rather than slow insertion into the membrane. The data were rationalized with a model that allows two membrane/probe configurations with distinct microenvironments. The analysis suggests that by monitoring the equilibration pattern of Patman, inferences can be made regarding the polarity of two microenvironments occupied by the probe, the distribution of the probe among those microenvironments, and the kinetics with which they relax to equilibrium.     

A Simple Insightful Approach to Investigating a Hospital Standardised Mortality Ratio: An Illustrative Case-Study

Background

Despite methodological concerns Hospital Standardised Mortality Ratios (HSMRs) are promoted as measures of performance. Hospitals that experience an increase in their HSMR are presented with a serious challenge but with little guidance on how to investigate this complex phenomenon. We illustrate a simple penetrating approach.

Methods

Retrospective analysis of routinely collected hospital admissions data comparing observed and expected deaths predicted by the Dr Foster Unit case mix adjustment method over three years (n = 74,860 admissions) in Shropshire and Telford NHS Trust Hospital (SaTH) constituting PRH (Princess Royal Hospital) and RSH (Royal Shrewsbury Hospital); whose HSMR increased from 99 in the year 2008/09 to 118 in the year 2009/10.

Results

The step up in HSMR was primarily located in PRH (109 to 130 vs. 105 to 118 RSH). Disentangling the HSMR by plotting run charts of observed and expected deaths showed that observed deaths were stable in RSH and PRH but expected deaths, especially at PRH, had fallen. The fall in expected deaths has two possible explanations–genuinely lower risk admissions or that the case-mix adjustment model is underestimating the risk of admissions perhaps because of inadequate clinical coding. There was no evidence that the case-mix profile of admissions had changed but there was considerable evidence that clinical coding process at PRH was producing a lower depth of coding resulting in lower expected mortality.

Conclusion

Knowing whether the change (increase/decrease) in HSMR is driven by the numerator or the denominator is a crucial pivotal first step in understanding a given HSMR and so such information should be an integral part of the HSMR reporting methodology.     

Increased Brain White Matter Axial Diffusivity Associated with Fatigue,Pain and Hyperalgesia in Gulf War Illness

Background

Gulf War exposures in 1990 and 1991 have caused 25% to 30% of deployed personnel to develop a syndrome of chronic fatigue, pain, hyperalgesia, cognitive and affective dysfunction.

Methods

Gulf War veterans (n = 31) and sedentary veteran and civilian controls (n = 20) completed fMRI scans for diffusion tensor imaging. A combination of dolorimetry, subjective reports of pain and fatigue were correlated to white matter diffusivity properties to identify tracts associated with symptom constructs.

Results

Gulf War Illness subjects had significantly correlated fatigue, pain, hyperalgesia, and increased axial diffusivity in the right inferior fronto-occipital fasciculus. ROC generated thresholds and subsequent binary regression analysis predicted CMI classification based upon axial diffusivity in the right inferior fronto-occipital fasciculus. These correlates were absent for controls in dichotomous regression analysis.

Conclusion

The right inferior fronto-occipital fasciculus may be a potential biomarker for Gulf War Illness. This tract links cortical regions involved in fatigue, pain, emotional and reward processing, and the right ventral attention network in cognition. The axonal neuropathological mechanism(s) explaining increased axial diffusivity may account for the most prominent symptoms of Gulf War Illness.     

Placebo Use in the United Kingdom: Results from a National Survey of Primary Care Practitioners

Objectives

Surveys in various countries suggest 17% to 80% of doctors prescribe ‘placebos’ in routine practice, but prevalence of placebo use in UK primary care is unknown.

Methods

We administered a web-based questionnaire to a representative sample of UK general practitioners. Following surveys conducted in other countries we divided placebos into ‘pure’ and ‘impure’. ‘Impure’ placebos are interventions with clear efficacy for certain conditions but are prescribed for ailments where their efficacy is unknown, such as antibiotics for suspected viral infections. ‘Pure’ placebos are interventions such as sugar pills or saline injections without direct pharmacologically active ingredients for the condition being treated. We initiated the survey in April 2012. Two reminders were sent and electronic data collection closed after 4 weeks.

Results

We surveyed 1715 general practitioners and 783 (46%) completed our questionnaire. Our respondents were similar to those of all registered UK doctors suggesting our results are generalizable. 12% (95% CI 10 to 15) of respondents used pure placebos while 97% (95% CI 96 to 98) used impure placebos at least once in their career. 1% of respondents used pure placebos, and 77% (95% CI 74 to 79) used impure placebos at least once per week. Most (66% for pure, 84% for impure) respondents stated placebos were ethical in some circumstances.

Conclusion and implications

Placebo use is common in primary care but questions remain about their benefits, harms, costs, and whether they can be delivered ethically. Further research is required to investigate ethically acceptable and cost-effective placebo interventions.     

Spectrum of T-DNA integrations for insertional mutagenesis of Histoplasma capsulatum

Agrobacterium-mediated transformation is being increasingly used for insertional mutagenesis of fungi. To better evaluate its effectiveness as a mutagen for the fungal pathogen Histoplasma capsulatum, we analyzed a collection of randomly selected T-DNA insertion mutants. Testing of different T-DNA element vectors engineered for transformation of fungi showed that pBHt2 provides the highest transformation efficiency and the lowest rate of vector backbone carryover. Sixty-eight individual T-DNA integrations were characterized by recovery of T-DNA ends and flanking genomic sequences. The right border (RB) end of the T-DNA is largely preserved whereas the left border (LB) end is frequently truncated. Analysis of T-DNA insertion sites confirms the lack of any integration hotspots in the Histoplasma genome. Relative to genes, T-DNA integrations show significant bias towards promoter regions at the expense of coding sequences. With consideration for potential promoter interruption and the demonstrated efficacy of intronic insertions, 61 % of mapped T-DNA insertions should impair gene expression or function. Mapping of T-DNA flanking sequences demonstrates 67 % of T-DNA integrations are integrations at a single chromosomal site and 31 % of T-DNA integrations are associated with large-scale chromosomal rearrangements. This characterization of T-DNA insertions in mutants selected without regard to phenotype supports application of Agrobacterium-mediated transformation as an insertional mutagen for genome-based screens and functional discovery of genes in Histoplasma.