Sialic Acid Glycobiology Unveils Trypanosoma cruzi Trypomastigote Membrane Physiology.

Trypanosoma cruzi, the flagellate protozoan agent of Chagas disease or American trypanosomiasis, is unable to synthesize sialic acids de novo. Mucins and trans-sialidase (TS) are substrate and enzyme, respectively, of the glycobiological system that scavenges sialic acid from the host in a crucial interplay for T. cruzi life cycle. The acquisition of the sialyl residue allows the parasite to avoid lysis by serum factors and to interact with the host cell. A major drawback to studying the sialylation kinetics and turnover of the trypomastigote glycoconjugates is the difficulty to identify and follow the recently acquired sialyl residues. To tackle this issue, we followed an unnatural sugar approach as bioorthogonal chemical reporters, where the use of azidosialyl residues allowed identifying the acquired sugar. Advanced microscopy techniques, together with biochemical methods, were used to study the trypomastigote membrane from its glycobiological perspective. Main sialyl acceptors were identified as mucins by biochemical procedures and protein markers. Together with determining their shedding and turnover rates, we also report that several membrane proteins, including TS and its substrates, both glycosylphosphatidylinositol-anchored proteins, are separately distributed on parasite surface and contained in different and highly stable membrane microdomains. Notably, labeling for α(1,3)Galactosyl residues only partially colocalize with sialylated mucins, indicating that two species of glycosylated mucins do exist, which are segregated at the parasite surface. Moreover, sialylated mucins were included in lipid-raft-domains, whereas TS molecules are not. The location of the surface-anchored TS resulted too far off as to be capable to sialylate mucins, a role played by the shed TS instead. Phosphatidylinositol-phospholipase-C activity is actually not present in trypomastigotes. Therefore, shedding of TS occurs via microvesicles instead of as a fully soluble form

Fragment-Based Approaches to the Development of Mycobacterium tuberculosis CYP121 Inhibitors.

The essential enzyme CYP121 is a target for drug development against antibiotic resistant strains of Mycobacterium tuberculosis. A triazol-1-yl phenol fragment 1 was identified to bind to CYP121 using a cascade of biophysical assays. Synthetic merging and optimization of 1 produced a 100-fold improvement in binding affinity, yielding lead compound 2 (KD = 15 μM). Deconstruction of 2 into its component retrofragments allowed the group efficiency of structural motifs to be assessed, the identification of more LE scaffolds for optimization and highlighted binding affinity hotspots. Structure-guided addition of a metal-binding pharmacophore onto LE retrofragment scaffolds produced low nanomolar (KD = 15 nM) CYP121 ligands. Elaboration of these compounds to target binding hotspots in the distal active site afforded compounds with excellent selectivity against human drug-metabolizing P450s. Analysis of the factors governing ligand potency and selectivity using X-ray crystallography, UV-vis spectroscopy, and native mass spectrometry provides insight for subsequent drug development.MEK was supported by a Commonwealth (University of Cambridge) Scholarship awarded in conjunction with the Cambridge Commonwealth Trust and Cambridge Overseas Trust. AGC and KJM were supported by grants from the BBSRC (Grant No: BB/I019669/1 and BB/I019227/1). GGJ received funding from the Ogden Trust and the Isaac Newton Trust administered through the University of Cambridge Bursary Scheme. DSCH was supported by a Croucher Cambridge International Scholarship awarded in conjunction between the Croucher Foundation and the Cambridge Overseas Trust. SAH was supported by an Oliphant Cambridge Australia Scholarship (App No: 10132070) awarded by the Cambridge Commonwealth Trust. The contributions of LBM and LPSC were supported by funds from the Francis Crick Institute, which receives its core funding principally from Wellcome Trust, Cancer Research UK, and the UK Medical Research Council (to LPSC - MC_UP_A253_1111) and funds from FAPESP, CNPq and CAPES-PDSE (to LBM - 2011/21232-1, 140079/2013-0, 99999.003125/2014-09).This is the final version of the article. It first appeared from the American Chemical Society via http://dx.doi.org/10.1021/acs.jmedchem.6b0000

Perspectives on the Trypanosoma cruzi-host cell receptor interaction

Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets

Cost effectiveness of preventing falls and improving mobility in people with Parkinson disease: protocol for an economic evaluation alongside a clinical trial

Background Cost of illness studies show that Parkinson disease (PD) is costly for individuals, the healthcare system and society. The costs of PD include both direct and indirect costs associated with falls and related injuries. Methods This protocol describes a prospective economic analysis conducted alongside a randomised controlled trial (RCT). It evaluates whether physical therapy is more cost effective than usual care from the perspective of the health care system. Cost effectiveness will be evaluated using a three-way comparison of the cost per fall averted and the cost per quality adjusted life year saved across two physical therapy interventions and a control group. Conclusion This study has the potential to determine whether targetted physical therapy as an adjunct to standard care can be cost effective in reducing falls in people with PD

Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli

Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.  Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins.  Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets

The Impact of Different Types of Assistive Devices on Gait Measures and Safety in Huntington's Disease

BACKGROUND: Gait and balance impairments lead to frequent falls and injuries in individuals with Huntington's disease (HD). Assistive devices (ADs) such as canes and walkers are often prescribed to prevent falls, but their efficacy is unknown. We systematically examined the effects of different types of ADs on quantitative gait measures during walking in a straight path and around obstacles. METHODS: Spatial and temporal gait parameters were measured in 21 subjects with HD as they walked across a GAITRite walkway under 7 conditions (i.e., using no AD and 6 commonly prescribed ADs: a cane, a weighted cane, a standard walker, and a 2, 3 or 4 wheeled walker). Subjects also were timed and observed for number of stumbles and falls while walking around two obstacles in a figure-of-eight pattern. RESULTS: Gait measure variability (i.e., coefficient of variation), an indicator of fall risk, was consistently better when using the 4WW compared to other ADs. Subjects also walked the fastest and had the fewest number of stumbles and falls when using the 4WW in the figure-of-eight course. Subjects walked significantly slower using ADs compared to no AD both across the GAITRite and in the figure-of-eight. Measures reflecting gait stability and safety improved with the 4WW but were made worse by some other ADs

Highlights of the São Paulo ISEV workshop on extracellular vesicles in cross-kingdom communication

In the past years, extracellular vesicles (EVs) have become an important field of research since EVs have been found to play a central role in biological processes. In pathogens, EVs are involved in several events during the host–pathogen interaction, including invasion, immunomodulation, and pathology as well as parasite–parasite communication. In this report, we summarised the role of EVs in infections caused by viruses, bacteria, fungi, protozoa, and helminths based on the talks and discussions carried out during the International Society for Extracellular Vesicles (ISEV) workshop held in São Paulo (November, 2016), Brazil, entitled Cross-organism Communication by Extracellular Vesicles: Hosts, Microbes and Parasites. © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.11Ysciescopu

Regulation of Hemocytes in Drosophila Requires dappled Cytochrome b5

A major category of mutant hematopoietic phenotypes in Drosophila is melanotic tumors or nodules, which consist of abnormal and overproliferated blood cells, similar to granulomas. Our analyses of the melanotic mutant dappled have revealed a novel type of gene involved in blood cell regulation. The dappled gene is an essential gene that encodes cytochrome b5, a conserved hemoprotein that participates in electron transfer in multiple biochemical reactions and pathways. Viable mutations of dappled cause melanotic nodules and hemocyte misregulation during both hematopoietic waves of development. The sexes are similarly affected, but hemocyte number is different in females and males of both mutants and wild type. Additionally, initial tests show that curcumin enhances the dappled melanotic phenotype and establish screening of endogenous and xenobiotic compounds as a route for analysis of cytochrome b5 function. Overall, dappled provides a tractable genetic model for cytochrome b5, which has been difficult to study in higher organisms

Human sit-to-stand transfer modeling towards intuitive and biologically-inspired robot assistance

© 2016, Springer Science+Business Media New York. Sit-to-stand (STS) transfers are a common human task which involves complex sensorimotor processes to control the highly nonlinear musculoskeletal system. In this paper, typical unassisted and assisted human STS transfers are formulated as optimal feedback control problem that finds a compromise between task end-point accuracy, human balance, energy consumption, smoothness of motion and control and takes further human biomechanical control constraints into account. Differential dynamic programming is employed, which allows taking the full, nonlinear human dynamics into consideration. The biomechanical dynamics of the human is modeled by a six link rigid body including leg, trunk and arm segments. Accuracy of the proposed modelling approach is evaluated for different human healthy and patient/elderly subjects by comparing simulations and experimentally collected data. Acceptable model accuracy is achieved with a generic set of constant weights that prioritize the different criteria. Finally, the proposed STS model is used to determine optimal assistive strategies suitable for either a person with specific body segment weakness or a more general weakness. These strategies are implemented on a robotic mobility assistant and are intensively evaluated by 33 elderlies, mostly not able to perform unassisted STS transfers. The validation results show a promising STS transfer success rate and overall user satisfaction