Pattern recognition and cellular immune responses to novel Mycobacterium tuberculosis-antigens in individuals from Belarus

Background: Tuberculosis (TB) is an enduring health problem worldwide and the emerging threat of multidrug resistant (MDR) TB and extensively drug resistant (XDR) TB is of particular concern. A better understanding of biomarkers associated with TB will aid to guide the development of better targets for TB diagnosis and for the development of improved TB vaccines. Methods: Recombinant proteins (n = 7) and peptide pools (n = 14) from M. tuberculosis (M.tb) antigens associated with M.tb pathogenicity, modification of cell lipids or cellular metabolism, were used to compare T cell immune responses defined by IFN-gamma production using a whole blood assay (WBA) from i) patients with TB, ii) individuals recovered from TB and iii) individuals exposed to TB without evidence of clinical TB infection from Minsk, Belarus. Results: We identified differences in M.tb target peptide recognition between the test groups, i.e. a frequent recognition of antigens associated with lipid metabolism, e.g. cyclopropane fatty acyl phospholipid synthase. The pattern of peptide recognition was broader in blood from healthy individuals and those recovered from TB as compared to individuals suffering from pulmonary TB. Detection of biologically relevant M.tb targets was confirmed by staining for intracellular cytokines (IL-2, TNF-alpha and IFN-gamma) in T cells from non-human primates (NHPs) after BCG vaccination. Conclusions: PBMCs from healthy individuals and those recovered from TB recognized a broader spectrum of M.tb antigens as compared to patients with TB. The nature of the pattern recognition of a broad panel of M.tb antigens will devise better strategies to identify improved diagnostics gauging previous exposure to M.tb; it may also guide the development of improved TB-vaccines.

Desenlaces del tratamiento de pacientes adultos con tuberculosis multiresistente y con resistencia extendida. Revisión sistemática.

Introducción: La tuberculosis es considerada una enfermedad de alta prevalencia a nivel mundial y un problema de salud pública por la disminución en la tasa de cura desde la aparición de TB con resistencia múltiple y extendida, por lo cual se requiere diseñar estrategias de manejo emergentes que permitan frenar el aumento en la incidencia de la TB a nivel mundial. Métodos: Se realizó una búsqueda sistemática de la literatura a través de PubMed y HINARI, dirigida a estudios que evaluaran los desenlaces de manejo de la TB MDR según los objetivos planteados por la última guía de la OMS1. Resultados: Se recolectaron 9 artículos de seguimiento a una cohorte en diferentes lugares del mundo según los criterios de inclusión, de la muestra recolectada en los 9 artículos, 4720 personas recibieron tratamiento desde el inicio, 4163 (88%) fueron TB MDR y 557 (12%) TB XDR. De esta muestra se excluyeron los transferidos a otras instituciones al hacer el análisis, quedando un total de 4455 casos. Se encontró de las muestras con el manejo individualizado, sin embargo la mortalidad continua siendo representativa y mayor en relación con algunas variables. Conclusiones: Los estudios evaluaron las múltiples estrategias de manejo en diferentes países sin obtener resultados contundentes sobre una estrategia de manejo estandarizada. La realización de un meta análisis no es posible por la pobre caracterización de los esquemas de tratamiento usados en los diferentes estudios y definiciones mal delineadas.

Trends in multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is an increasing global problem. The extent and burden of MDR-TB varies significantly from country to country and region to region. Globally, about three per cent of all newly diagnosed patients have MDR-TB and the proportion is higher in patients who had previously received anti-tuberculosis (anti-TB) treatment reflecting the failure of programs designed to ensure complete cure of patients with tuberculosis. The management of MDR-TB is a challenge that should be undertaken by experienced clinicians at centers equipped with reliable laboratory services and implementation of DOTS-Plus strategy.

Structural studies of shikimate 5-dehydrogenase from Mycobacterium tuberculosis

Tuberculosis (TB) remains the leading cause of mortality due to a single bacterial pathogen, Mycobacterium tuberculosis. The reemergence of TB as a potential public health threat, the high susceptibility of human immunodeficiency virus-infected persons to the disease, the proliferation of multi-drug-resistant strains (MDR-TB) and, more recently, of extensively drug resistant isolates (XDR-TB) have created a need for the development of new antimycobacterial agents. Amongst the several proteins and/or enzymes to be studied as potential targets to develop novel drugs against M. tuberculosis, the enzymes of the shikimate pathway are attractive targets because they are essential in algae, higher plants, bacteria, and fungi, but absent from mammals. The mycobacterial shikimate pathway leads to the biosynthesis of chorismate, which is a precursor of aromatic amino acids, naphthoquinones, menaquinones, and mycobactins. Here we report the structural studies by homology modeling and circular dichroism spectroscopy of the shikimate dehydrogenase from M. tuberculosis (MtSDH), which catalyses the fourth step of the shikimate pathway. Our structural models show that the MtSDH has similar structure to other shikimate dehydrogenase structures previously reported either in presence or absence of NADP, despite the low amino acid sequence identity. The circular dichroism spectra corroborate the secondary structure content observed in the MtSDH models developed. The enzyme was stable up to 50 degrees C presenting a cooperative unfolding profile with the midpoint of the unfolding temperature value of similar to 63-64 degrees C, as observed in the unfolding experiment followed by circular dichroism. Our MtSDH structural models and circular dichroism data showed small conformational changes induced by NADP binding. We hope that the data presented here will assist the rational design of antitubercular agents.

Implication of the RDRio Mycobacterium tuberculosis sublineage in multidrug resistant tuberculosis in Portugal

Multidrug and extensively drug resistant Mycobacterium tuberculosis are a threat to tuberculosis control programs. Genotyping methods, such as spoligotyping and MIRU-VNTR typing (Mycobacterial Interspersed Repetitive Units), are useful in monitoring potentially epidemic strains and estimating strain phylogenetic lineages and/or genotypic families. M. tuberculosis Latin American Mediterranean (LAM) family is a major worldwide contributor to tuberculosis (TB). LAM specific molecular markers, Ag85C(103) single nucleotide polymorphism (SNP) and RDRio long-sequence polymorphism (LSP), were used to characterize spoligotype signatures from 859 patient isolates from Portugal. LAM strains were found responsible for 57.7% of all tuberculosis cases. Strains with the RDRio deletion (referred to as RDRio) were estimated to represent 1/3 of all the strains and over 60% of the multidrug resistant (MDR) strains. The major spoligotype signature SIT20 belonging to the LAM1 RDRio sublineage, represented close to 1/5th of all the strains, over 20% of which were MDR. Analysis of published datasets according to stipulated 12 loci MIRU-VNTR RDRio signatures revealed that 96.3% (129/134) of MDR and extensively drug resistant (XDR) clusters were RDRio. This is the first report associating the LAM RDRio sublineage with MDR. These results are an important contribution to the monitoring of these strains with heightened transmission for future endeavors to arrest MDR-TB and XDR-TB. (c) 2012 Elsevier B.V. All rights reserved.

In Vitro and In Vivo Activities of Ruthenium(II) Phosphine/Diimine/Picolinate Complexes (SCAR) against Mycobacterium tuberculosis

Rifampicin, discovered more than 50 years ago, represents the last novel class of antibiotics introduced for the first-line treatment of tuberculosis. Drugs in this class form part of a 6-month regimen that is ineffective against MDR and XDR TB, and incompatible with many antiretroviral drugs. Investments in R&D strategies have increased substantially in the last decades. However, the number of new drugs approved by drug regulatory agencies worldwide does not increase correspondingly. Ruthenium complexes (SCAR) have been tested in our laboratory and showed promising activity against Mycobacterium tuberculosis. These complexes showed up to 150 times higher activity against MTB than its organic molecule without the metal (free ligand), with low cytotoxicity and high selectivity. In this study, promising results inspired us to seek a better understanding of the biological activity of these complexes. The in vitro biological results obtained with the SCAR compounds were extremely promising, comparable to or better than those for first-line drugs and drugs in development. Moreover, SCAR 1 and 4, which presented low acute toxicity, were assessed by Ames test, and results demonstrated absence of mutagenicity. © 2013 Pavan et al.

Determinação do perfil pré-clínico da atividade anti-tuberculose in vitro e in vivo de complexos heterolépticos de Rutênio(II) com fosfinas. diiminas e picolinato como ligantes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Synthesis and evaluation of a pyrazinoic acid prodrug in Mycobacterium tuberculosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Multidrug- and extensively drug-resistant tuberculosis

We evaluated risk factors and treatment outcomes associated with multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) in Germany in 2004–2006. In 177 (4%) of 4,557 culture-positive TB cases, Mycobacterium tuberculosis isolates were identified as MDR TB; an additional 7 (0.15%) met criteria for XDR TB. Of these 184 patients, 148 (80%) were born in countries of the former Soviet Union. In patients with XDR TB, hospitalization was longer (mean ± SD 202 ± 130 vs. 123 ± 81 days; p = 0.015) and resistance to all first-line drugs was more frequent (36% vs. 86%; p = 0.013) than in patients with MDR TB. Seventy-four (40%) of these 184 patients received treatment with linezolid. Treatment success rates ranged from 59% for the entire cohort (59% for MDR TB and 57% for XDR TB) to 87% for those with a definitive outcome (n = 125; 89% for MDR TB and 80% for XDR TB). Extensive drug susceptibility testing and availability of second- and third-line drugs under inpatient management conditions permit relatively high treatment success rates in MDR- and XDR TB.

1-D hydrogen-bonded organization of hexanuclear {3d-4f-5d} complexes: evidence for slow relaxation of the magnetization for [{LMe2Ni(H2O)Ln(H2O)4.5}2{W(CN)8}2] with Ln = Tb and Dy

Heterometallic {3d-4f-5d} aggregates with formula [{LMe2Ni(H2O)Ln(H2O)4.5}2{W(CN)8}2]·15H2O, (LMe2 stands for N,N-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato) Schiff-base ligand) with Ln = Gd, Tb, Dy, have been obtained by reacting bimetallic [LMe2Ni(H2O)2Ln(NO3)3] and Cs3{W(CN)8} in H2O. The hexanuclear complexes are organized in 1-D arrays by means of hydrogen bonds established between the solvent molecules coordinated to Ln and the CN ligands of an octacyanometallate moiety. The X-ray structure was solved for the Tb derivative. Magnetic behavior indicates ferromagnetic {W–Ni} and {Ni–Ln} interactions (JNiW = 18.5 cm-1, JNiGd = 1.85 cm-1) as well as ferromagnetic intermolecular interactions mediated by the H-bonds. Dynamic magnetic susceptibility studies reveal slow magnetic relaxation processes for the Tb and Dy derivatives, suggesting SMM type behavior for these compounds.

Search for the Production of Narrow tb̅ Resonances in 1.9 fb-1 of pp̅ Collisions at √s=1.96 TeV

We present new limits on resonant tb production in proton-antiproton collisions at 1.96 TeV, using 1.9 fb^-1 of data recorded with the CDF II detector at the Fermilab Tevatron. We reconstruct a candidate mass in events with a lepton, neutrino candidate, and two or three jets, and search for anomalous tb production as modeled by W'->tb. We set a new limit on a right-handed W' with standard model-like coupling, excluding any mass below 800 GeV at 95% C.L. The cross-section for any narrow, resonant tb production between 750 and 950 GeV is found to be less than 0.28 pb at 95% C.L. We also present an exclusion of the W' coupling strength versus W' mass over the range 300 to 950 GeV.

Global, Local and Vector-Valued Tb Theorems on Non-Homogeneous Metric Spaces

Various Tb theorems play a key role in the modern harmonic analysis. They provide characterizations for the boundedness of Calderón-Zygmund type singular integral operators. The general philosophy is that to conclude the boundedness of an operator T on some function space, one needs only to test it on some suitable function b. The main object of this dissertation is to prove very general Tb theorems. The dissertation consists of four research articles and an introductory part. The framework is general with respect to the domain (a metric space), the measure (an upper doubling measure) and the range (a UMD Banach space). Moreover, the used testing conditions are weak. In the first article a (global) Tb theorem on non-homogeneous metric spaces is proved. One of the main technical components is the construction of a randomization procedure for the metric dyadic cubes. The difficulty lies in the fact that metric spaces do not, in general, have a translation group. Also, the measures considered are more general than in the existing literature. This generality is genuinely important for some applications, including the result of Volberg and Wick concerning the characterization of measures for which the analytic Besov-Sobolev space embeds continuously into the space of square integrable functions. In the second article a vector-valued extension of the main result of the first article is considered. This theorem is a new contribution to the vector-valued literature, since previously such general domains and measures were not allowed. The third article deals with local Tb theorems both in the homogeneous and non-homogeneous situations. A modified version of the general non-homogeneous proof technique of Nazarov, Treil and Volberg is extended to cover the case of upper doubling measures. This technique is also used in the homogeneous setting to prove local Tb theorems with weak testing conditions introduced by Auscher, Hofmann, Muscalu, Tao and Thiele. This gives a completely new and direct proof of such results utilizing the full force of non-homogeneous analysis. The final article has to do with sharp weighted theory for maximal truncations of Calderón-Zygmund operators. This includes a reduction to certain Sawyer-type testing conditions, which are in the spirit of Tb theorems and thus of the dissertation. The article extends the sharp bounds previously known only for untruncated operators, and also proves sharp weak type results, which are new even for untruncated operators. New techniques are introduced to overcome the difficulties introduced by the non-linearity of maximal truncations.

Coherent phonons in pyrochlore titanates A(2)Ti(2)O(7) (A = Dy, Gd, Tb): A phase transition in Dy2Ti2O7 at 110 K

We study the generation of coherent optical phonons in spin-frustrated pyrochlore single crystals Dy2Ti2O7, Gd2Ti2O7, and Tb2Ti2O7 using femtosecond laser pulses (65 fs, 1.57 eV) in degenerate time-resolved transmission experiments as a function of temperature from 4 to 296 K. At 4 K, two coherent phonons are observed at similar to 5.3 THz (5.0 THz) and similar to 9.3 THz (9.4 THz) for Dy2Ti2O7 (Gd2Ti2O7), whereas three coherent phonons are generated at similar to 5.0, 8.6, and 9.7 THz for Tb2Ti2O7. In the case of spin-ice Dy2Ti2O7, a clear discontinuity is observed in the linewidths of both the coherent phonons as well as in the phase of lower-energy coherent phonon mode, indicating a subtle structural change at 110 K. Another important observation is a phase difference of pi between the modes in all the samples, thus suggesting that the driving forces behind the generation of these modes could be different in nature, unlike a purely impulsive or displacive mechanism.

Decomposition temperatures of Cu2Ln2O5 (Ln = Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds

The equilibrium decomposition temperatures of Cu2Ln2O5 (Ln = Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds have been measured using a combined DTA-TGA apparatus under a flowing Ar + O2 gas mixture, in which the partial pressure of oxygen was controlled at 5.0 × 103 Pa. The Cu2Ln2O5 compounds yield Ln2O3 and Cu2O on decomposition. The decomposition temperature increases monotonically with the atomic number of the lanthanide element. This suggests that the stability of the Cu2Ln2O5 compounds with respect to the component binary oxides increases with decreasing radius of the Ln3+ ion.