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A model based on a specific phantom, called QuAArC, has been designed for the evaluation of planning and verification systems of complex radiotherapy treatments, such as volumetric modulated arc therapy (VMAT). This model uses the high accuracy provided by the Monte Carlo (MC) simulation of log files and allows the experimental feedback from the high spatial resolution of films hosted in QuAArC. This cylindrical phantom was specifically designed to host films rolled at different radial distances able to take into account the entrance fluence and the 3D dose distribution. Ionization chamber measurements are also included in the feedback process for absolute dose considerations. In this way, automated MC simulation of treatment log files is implemented to calculate the actual delivery geometries, while the monitor units are experimentally adjusted to reconstruct the dose-volume histogram (DVH) on the patient CT. Prostate and head and neck clinical cases, previously planned with Monaco and Pinnacle treatment planning systems and verified with two different commercial systems (Delta4 and COMPASS), were selected in order to test operational feasibility of the proposed model. The proper operation of the feedback procedure was proved through the achieved high agreement between reconstructed dose distributions and the film measurements (global gamma passing rates > 90% for the 2%/2 mm criteria). The necessary discretization level of the log file for dose calculation and the potential mismatching between calculated control points and detection grid in the verification process were discussed. Besides the effect of dose calculation accuracy of the analytic algorithm implemented in treatment planning systems for a dynamic technique, it was discussed the importance of the detection density level and its location in VMAT specific phantom to obtain a more reliable DVH in the patient CT. The proposed model also showed enough robustness and efficiency to be considered as a pre-treatment VMAT verification system., This work was supported by the Spanish Ministry of Science and Technology (SAF2011-27116; IPT-2011-1480-900000) and the European Regional Development Fund.

Ribonucleotide reductases (RNRs) catalyze the reduction of ribonucleotides to deoxyribonucleotides, the building blocks for DNA synthesis, and are found in all but a few organisms. RNRs use radical chemistry to catalyze the reduction reaction. Despite RNR having evolved several mechanisms for generation of different kinds of essential radicals across a large evolutionary time frame, this initial radical is normally always channelled to a strictly conserved cysteine residue directly adjacent to the substrate for initiation of substrate reduction, and this cysteine has been found in the structures of all RNRs solved to date. We present the crystal structure of an anaerobic RNR from the extreme thermophile Thermotoga maritima (tmNrdD), alone and in several complexes, including with the allosteric effector dATP and its cognate substrate CTP. In the crystal structure of the enzyme as purified, tmNrdD lacks a cysteine for radical transfer to the substrate pre-positioned in the active site. Nevertheless activity assays using anaerobic cell extracts from T. maritima demonstrate that the class III RNR is enzymatically active. Other genetic and microbiological evidence is summarized indicating that the enzyme is important for T. maritima. Mutation of either of two cysteine residues in a disordered loop far from the active site results in inactive enzyme. We discuss the possible mechanisms for radical initiation of substrate reduction given the collected evidence from the crystal structure, our activity assays and other published work. Taken together, the results suggest either that initiation of substrate reduction may involve unprecedented conformational changes in the enzyme to bring one of these cysteine residues to the expected position, or that alternative routes for initiation of the RNR reduction reaction may exist. Finally, we present a phylogenetic analysis showing that the structure of tmNrdD is representative of a new RNR subclass IIIh, present in all Thermotoga species plus a wider group of bacteria from the distantly related phyla Firmicutes, Bacteroidetes and Proteobacteria., SCOPUS: ar.j, info:eu-repo/semantics/published

Swedish Research Council (VR) Swedish Academy of Sciences (KVA, Soderberg Foundation) Karolinska Institutet-DPA EU Network of Excellence EviMalar Plasmodium falciparum is the most lethal of the human malaria parasites. the virulence is associated with the capacity of the infected red blood cell (iRBC) to sequester inside the deep microvasculature where it may cause obstruction of the blood-flow when binding is excessive. Rosetting, the adherence of the iRBC to uninfected erythrocytes, has been found associated with severe malaria and found to be mediated by the NTS-DBL1 alpha-domain of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1). Here we show that the reactivity of plasma of Cameroonian children with the surface of the FCR3S1.2-iRBC correlated with the capacity to disrupt rosettes and with the antibody reactivity with a recombinant PfEMP1 (NTS-DBL1 alpha of IT4(var60)) expressed by parasite FCR3S1.2. the plasma-reactivity in a microarray, consisting of 96 overlapping 15-mer long peptides covering the NTS-DBL1 alpha domain from IT4var60 sequence, was compared with their capacity to disrupt rosettes and we identified five peptides where the reactivity were correlated. Three of the peptides were localized in subdomain-1 and 2. the other two peptide-sequences were localized in the NTS-domain and in subdomain-3. Further, principal component analysis and orthogonal partial least square analysis generated a model that supported these findings. in conclusion, human antibody reactivity with short linear-peptides of NTS-DBL1 alpha of PfEMP1 suggests subdomains 1 and 2 to hold anti-rosetting epitopes recognized by anti-rosetting antibodies. the data suggest rosetting to be mediated by the variable areas of PfEMP1 but also to involve structurally relatively conserved areas of the molecule that may induce biologically active antibodies. Karolinska Inst, Dept Microbiol Tumor & Cell Biol MTC, Stockholm, Sweden Karolinska Inst, Dept Lab Med, Therapeut Immunol TIM, Stockholm, Sweden Karolinska Univ Hosp, CAST, Huddinge, Sweden Univ Estadual Campinas, Dept Biochem, Campinas, SP, Brazil Universidade Federal de São Paulo, EPM, São Paulo, Brazil Web of Science

Wellcome Trust/MRC Joint Call in Neurodegeneration award United Kingdom Medical Research Council Wellcome Trust Parkinson's Disease UK Kattan Trust Objectives: To compare the dopaminergic neuronal imaging features of different subtypes of genetic Parkinson's Disease.Methods: A retrospective study of genetic Parkinson's diseases cases in which DaTSCAN (123I-FP-CIT) had been performed. Specific non-displaceable binding was calculated for bilateral caudate and putamen for each case. the right: left asymmetry index and striatal asymmetry index was calculated.Results: Scans were available from 37 cases of monogenetic Parkinson's disease (7 glucocerebrosidase (GBA) mutations, 8 alpha-synuclein, 3 LRRK2, 7 PINK1, 12 Parkin). the asymmetry of radioligand uptake for Parkinson's disease with GBA or LRRK2 mutations was greater than that for Parkinson's disease with alpha synuclein, PINK1 or Parkin mutations.Conclusions: the asymmetry of radioligand uptake in Parkinsons disease associated with GBA or LRRK2 mutations suggests that interactions with additional genetic or environmental factors may be associated with dopaminergic neuronal loss. UCL, Dept Clin Neurosci, Inst Neurol, London, England Birmingham Womens Hosp, Reg Genet Unit, Dept Clin Genet, Birmingham, W Midlands, England Natl Taiwan Univ Hosp, Coll Med, Dept Neurol, Taipei, Taiwan Natl Taiwan Univ Hosp, Coll Med, Dept Nucl Med, Taipei, Taiwan Hosp Israelita Albert Einstein, Inst Israelita Ensino & Pesquisa Albert Einstein, São Paulo, Brazil Hosp Univ Insular Gran Canaria, Dept Neurol, Parkinsons & Movement Disorders Unit, Las Palmas Gran Canaria, Spain Univ Salerno, Ctr Neurodegenerat Dis, Salerno, Fisciano Provin, Italy UCL, Inst Neurol, Sobell Dept Motor Sci, London, England Universidade Federal de São Paulo, Dept Neurol, São Paulo, Brazil Erasmus MC, Dept Clin Genet, Rotterdam, Netherlands Aristotle Univ Thessaloniki, G Papanikolaou Hosp, Dept Neurol 3, GR-54006 Thessaloniki, Greece Gen Hosp S Michele AOB G Brotzu, Neurol Serv, Cagliari, Italy Gen Hosp S Michele AOB G Brotzu, Stroke Unit, Cagliari, Italy Univ Bologna, Dept Biomed & Neuromotor Sci, Bologna, Italy Universidade Federal de São Paulo UNIFESP, EPM, Div Movement Disorders, São Paulo, Brazil UCL Inst Neurol, Dept Mol Neurosci, London, England Univ Navarra, Div Neurosci, Ctr Appl Med Res, Neurogenet Lab, E-31080 Pamplona, Spain CNR, Inst Biostruct & Bioimaging, I-80125 Naples, Italy Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, Stockholm, Sweden Universidade Federal de São Paulo, Dept Neurol, São Paulo, Brazil Universidade Federal de São Paulo UNIFESP, EPM, Div Movement Disorders, São Paulo, Brazil Wellcome Trust/MRC Joint Call in Neurodegeneration award: WT089698 United Kingdom Medical Research Council: G1001983 Web of Science