Trypanosoma cruzi CYP51 Inhibitor Derived from a Mycobacterium tuberculosis Screen Hit

Enzyme sterol 14α-demethylase (CYP51) is a well-established target for anti-fungal therapy and is a prospective target for Chagas' disease therapy. We previously identified a chemical scaffold capable of delivering a variety of chemical structures into the CYP51 active site. In this work the binding modes of several second generation compounds carrying this scaffold were determined in high-resolution co-crystal structures with CYP51 of Mycobacterium tuberculosis. Subsequent assays against CYP51 in Trypanosoma cruzi, the agent of Chagas' disease, demonstrated that two of the compounds bound tightly to the enzyme. Both were tested for inhibitory effects against T. cruzi and the related protozoan parasite Trypanosoma brucei. One of the compounds had potent, selective anti–T. cruzi activity in infected mouse macrophages. This compound is currently being evaluated in animal models of Chagas' disease. Discrimination between T. cruzi and T. brucei CYP51 by the inhibitor was largely based on the variability of a single amino acid residue at a critical position in the active site. Our work is aimed at rational design of potent and highly selective CYP51 inhibitors with potential to become therapeutic drugs. Drug selectivity to prevent host–pathogen cross-reactivity is pharmacologically important, because CYP51 is present in human host

Neonatal erythropoiesis and subsequent anemia in HIV-positive and HIV-negative Zimbabwean babies during the first year of life: a longitudinal study

BACKGROUND: Anemia is common in HIV infection and independently associated with disease progression and mortality. The pathophysiology of HIV-related anemia is not well understood especially in infancy. METHODS: We conducted a longitudinal cohort study nested within the Zimbabwe Vitamin A for Mothers and Babies Project. We measured hemoglobin, erythropoietin (EPO), serum transferrin receptor (TfR) and serum ferritin at 6 weeks, 3 and 6 months of age and hemoglobin at 9 and 12 months in 3 groups of randomly selected infants: 136 born to HIV-negative mothers, and 99 born to HIV-positive mothers and who were infected themselves by 6 weeks of age, and 324 born to HIV-positive mothers but who did not become infected in the 6 months following birth. RESULTS: At one year of age, HIV-positive infants were 5.26 (adjusted odds ratio, P < 0.001) times more likely to be anemic compared to HIV-negative infants. Among, HIV-negative infants, EPO was or tended to be inversely associated with hemoglobin and was significantly positively associated with TfR throughout the first 6 months of life; TfR was significantly inversely associated with ferritin at 6 months; and EPO explained more of the variability in TfR than did ferritin. Among infected infants, the inverse association of EPO to hemoglobin was attenuated during early infancy, but significant at 6 months. Similar to HIV-negative infants, EPO was significantly positively associated with TfR throughout the first 6 months of life. However, the inverse association between TfR and ferritin observed among HIV-negative infants at 6 months was not observed among infected infants. Between birth and 6 months, mean serum ferritin concentration declined sharply (by ~90%) in all three groups of babies, but was significantly higher among HIV-positive compared to HIV-negative babies at all time points. CONCLUSION: HIV strongly increases anemia risk and confounds interpretation of hematologic indicators in infants. Among HIV-infected infants, the EPO response to anemia is attenuated near the time of infection in the first weeks of life, but normalizes by 6 months

Molecular Interpretation of ACTH-β-Endorphin Coaggregation: Relevance to Secretory Granule Biogenesis

Peptide/protein hormones could be stored as non-toxic amyloid-like structures in pituitary secretory granules. ACTH and β-endorphin are two of the important peptide hormones that get co-stored in the pituitary secretory granules. Here, we study molecular interactions between ACTH and β-endorphin and their colocalization in the form of amyloid aggregates. Although ACTH is known to be a part of ACTH-β-endorphin aggregate, ACTH alone cannot aggregate into amyloid under various plausible conditions. Using all atom molecular dynamics simulation we investigate the early molecular interaction events in the ACTH-β-endorphin system, β-endorphin-only system and ACTH-only system. We find that β-endorphin and ACTH formed an interacting unit, whereas negligible interactions were observed between ACTH molecules in ACTH-only system. Our data suggest that ACTH is not only involved in interaction with β-endorphin but also enhances the stability of mixed oligomers of the entire system

Hygiene, Sanitation, and Water: Forgotten Foundations of Health

As the first article in a four-part PLoS Medicine series on water and sanitation, Jamie Bartram and Sandy Cairncross argue that the massive burden of ill health associated with poor hygiene, sanitation, and water supply demands more attention from health professionals and policymakers

A prospective, double-blind, randomized, controlled clinical trial comparing standard wound care with adjunctive hyperbaric oxygen therapy (HBOT) to standard wound care only for the treatment of chronic, non-healing ulcers of the lower limb in patients with diabetes mellitus: a study protocol

<p>Abstract</p> <p>Background</p> <p>It has been suggested that the use of adjunctive hyperbaric oxygen therapy improves the healing of diabetic foot ulcers, and decreases the risk of lower extremity amputations. A limited number of studies have used a double blind approach to evaluate the efficacy of hyperbaric oxygen therapy in the treatment of diabetic ulcers. The primary aim of this study is to assess the efficacy of hyperbaric oxygen therapy plus standard wound care compared with standard wound care alone in preventing the need for major amputation in patients with diabetes mellitus and chronic ulcers of the lower limb.</p> <p>Methods/Design</p> <p>One hundred and eighteen (59 patients per arm) patients with non-healing diabetic ulcers of the lower limb, referred to the Judy Dan Research and Treatment Centre are being recruited if they are at least 18 years of age, have either Type 1 or 2 diabetes with a Wagner grading of foot lesions 2, 3 or 4 on lower limb not healing for at least 4 weeks. Patients receive hyperbaric oxygen therapy every day for 6 weeks during the treatment phase and are provided ongoing wound care and weekly assessments. Patients are required to return to the study centre every week for an additional 6 weeks of follow-up for wound evaluation and management. The primary outcome is freedom from having, or meeting the criteria for, a major amputation (below knee amputation, or metatarsal level) up to 12 weeks after randomization. The decision to amputate is made by a vascular surgeon. Other outcomes include wound healing, effectiveness, safety, healthcare resource utilization, quality of life, and cost-effectiveness. The study will run for a total of about 3 years.</p> <p>Discussion</p> <p>The results of this study will provide detailed information on the efficacy of hyperbaric oxygen therapy for the treatment of non-healing ulcers of the lower limb. This will be the first double-blind randomized controlled trial for this health technology which evaluates the efficacy of hyperbaric oxygen therapy in prevention of amputations in diabetic patients.</p> <p>Trial registration</p> <p>ClinicalTrials.gov Identifier: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00621608">NCT00621608</a></p

Ca2+ Regulates the Drosophila Stoned-A and Stoned-B Proteins Interaction with the C2B Domain of Synaptotagmin-1

The dicistronic Drosophila stoned gene is involved in exocytosis and/or endocytosis of synaptic vesicles. Mutations in either stonedA or stonedB cause a severe disruption of neurotransmission in fruit flies. Previous studies have shown that the coiled-coil domain of the Stoned-A and the µ-homology domain of the Stoned-B protein can interact with the C2B domain of Synaptotagmin-1. However, very little is known about the mechanism of interaction between the Stoned proteins and the C2B domain of Synaptotagmin-1. Here we report that these interactions are increased in the presence of Ca2+. The Ca2+-dependent interaction between the µ-homology domain of Stoned-B and C2B domain of Synaptotagmin-1 is affected by phospholipids. The C-terminal region of the C2B domain, including the tryptophan-containing motif, and the Ca2+ binding loop region that modulate the Ca2+-dependent oligomerization, regulates the binding of the Stoned-A and Stoned-B proteins to the C2B domain. Stoned-B, but not Stoned-A, interacts with the Ca2+-binding loop region of C2B domain. The results indicate that Ca2+-induced self-association of the C2B domain regulates the binding of both Stoned-A and Stoned-B proteins to Synaptotagmin-1. The Stoned proteins may regulate sustainable neurotransmission in vivo by binding to Ca2+-bound Synaptotagmin-1 associated synaptic vesicles

A practical guide to the simultaneous determination of protein structure and dynamics using metainference

Accurate protein structural ensembles can be determined with metainference, a Bayesian inference method that integrates experimental information with prior knowledge of the system and deals with all sources of uncertainty and errors as well as with system heterogeneity. Furthermore, metainference can be implemented using the metadynamics approach, which enables the computational study of complex biological systems requiring extensive conformational sampling. In this chapter, we provide a step-by-step guide to perform and analyse metadynamic metainference simulations using the ISDB module of the open-source PLUMED library, as well as a series of practical tips to avoid common mistakes. Specifically, we will guide the reader in the process of learning how to model the structural ensemble of a small disordered peptide by combining state-of-the-art molecular mechanics force fields with nuclear magnetic resonance data, including chemical shifts, scalar couplings and residual dipolar couplings.Comment: 49 pages, 9 figure

Structure of the pentameric ligand-gated ion channel ELIC cocrystallized with its competitive antagonist acetylcholine

ELIC, the pentameric ligand-gated ion channel from Erwinia chrysanthemi, is a prototype for Cys-loop receptors. Here we show that acetylcholine is a competitive antagonist for ELIC. We determine the acetylcholine–ELIC cocrystal structure to a 2.9-Å resolution and find that acetylcholine binding to an aromatic cage at the subunit interface induces a significant contraction of loop C and other structural rearrangements in the extracellular domain. The side chain of the pore-lining residue F247 reorients and the pore size consequently enlarges, but the channel remains closed. We attribute the inability of acetylcholine to activate ELIC primarily to weak cation-π and electrostatic interactions in the pocket, because an acetylcholine derivative with a simple quaternary-to-tertiary ammonium substitution activates the channel. This study presents a compelling case for understanding the structural underpinning of the functional relationship between agonism and competitive antagonism in the Cys-loop receptors, providing a new framework for developing novel therapeutic drugs

A healthy mistrust: how worldview relates to attitudes about breast cancer screening in a cross-sectional survey of low-income women

<p>Abstract</p> <p>Background</p> <p>Perceived racial discrimination is one factor which may discourage ethnic minorities from using healthcare. However, existing research only partially explains why some persons do accept health promotion messages and use preventive care, while others do not. This analysis explores 1) the psychosocial characteristics of those, within disadvantaged groups, who identify their previous experiences as racially discriminatory, 2) the extent to which perceived racism is associated with broader perspectives on societal racism and powerlessness, and 3) how these views relate to disadvantaged groups' expectation of mistreatment in healthcare, feelings of mistrust, and motivation to use care.</p> <p>Methods</p> <p>Using survey data from 576 African-American women, we explored the prevalence and predictors of beliefs and experiences related to social disengagement, racial discrimination, desired and actual racial concordance with medical providers, and fear of medical research. We then used both sociodemographic characteristics, and experiences and attitudes about disadvantage, to model respondents' scores on an index of personal motivation to receive breast cancer screening, measuring screening knowledge, rejection of fatalistic explanatory models of cancer, and belief in early detection, and in collaborative models of patient-provider responsibility.</p> <p>Results</p> <p>Age was associated with lower motivation to screen, as were depressive symptoms, anomie, and fear of medical research. Motivation was low among those more comfortable with African-American providers, regardless of current provider race. However, greater awareness of societal racism positively predicted motivation, as did talking to others when experiencing discrimination. Talking was most useful for women with depressive symptoms.</p> <p>Conclusion</p> <p>Supporting the Durkheimian concepts of both anomic and altruistic suicide, both disengagement (depression, anomie, vulnerability to victimization, and discomfort with non-Black physicians) as well as over-acceptance (low awareness of discrimination in society) predict poor health maintenance attitudes in disadvantaged women. Women who recognize their connection to other African-American women, and who talk about negative experiences, appear most motivated to protect their health.</p