Estudis estructurals dels canvis conformacionals de les E3 ubiquitin lligases per RMN

L'estudi a nivell molecular de la ruta de senyalització activada per TGF-B té un impacte notable en el panorama actual donada la seva implicació en processos autoimmunitaris i carcinogènics. D'altra banda, l'elucidació a nivell estructural dels mecanismes moleculars que permeten a les ubiquitin lligases de tipus E3 marcar específicament llurs dianes per a la degradació proteosòmica - entre d'altres - resulta fonamental donada la seva importància pel que fa al control sobre el turnover proteic a nivell intracel•lular. En aquest projecte es pretén elucidar els mecanismes d'activació i catlàlisi de les ubiquitin lligases E3 tipus HECT Smurf1 i Nedd4L al mateix temps que se n'estudia la implicació en la regulació dels agents missatgers de la ruta del TGF-B. Així, la tasca es divideix en tres sub-projectes els quals se centren en a) l'estudi de la interacció d'aquestes lligases amb llurs dianes; b) l'elucidació del mecanisme d'activació i c) del de catàlisi d'aquests enzims. Per tal d'assolir aquests objectius ens servim principalment dels avantatges que ens aporta la Ressonància Magnètica Nuclear i altres tècniques biofísiques, principalment la ITC. Durant el temps que he gaudit de la beca FI, m'he centrat principalment en la preparació de pèptids per SPPS, llur purificació per HPLC i caracterització per MS i RMN. Aquests pèptids representen diferents patrons de fosforilació de certes dianes de les lligases esmentades, de manera que han estat emprats per a l'estudi d'interaccions proteïna-proteïna per ITC i RMN. M'he iniciat doncs en l'ús d'aquestes tècniques. D'altra banda, també he preparat mostres protèiques mitjançant l'ús de sistemes d'expressió bacterians basats en E.coli, incloent l'amplificació i clonació del gen que codifica per la proteïna d'interés així com la seva expressió, purificació i caracterització per MS i RMN.

Sample preparation for two-dimensional gel electrophoresis.

The choice of sample preparation protocol is a critical influential factor for isoelectric focusing which in turn affects the two-dimensional gel result in terms of quality and protein species distribution. The optimal protocol varies depending on the nature of the sample for analysis and the properties of the constituent protein species (hydrophobicity, tendency to form aggregates, copy number) intended for resolution. This review explains the standard sample buffer constituents and illustrates a series of protocols for processing diverse samples for two-dimensional gel electrophoresis, including hydrophobic membrane proteins. Current methods for concentrating lower abundance proteins, by removal of high abundance proteins, are also outlined. Finally, since protein staining is becoming increasingly incorporated into the sample preparation procedure, we describe the principles and applications of current (and future) pre-electrophoretic labelling methods.

Evaluation by ELISA of Anisakis simplex Larval Antigen Purified by Affinity Chromatography

In order to improve the specificity and sensitivity of the techniques for the human anisakidosis diagnosis, a method of affinity chromatography for the purification of species-specific antigens from Anisakis simplex third-stage larvae (L3) has been developed. New Zealand rabbits were immunized with A. simplex or Ascaris suum antigens or inoculated with Toxocara canis embryonated eggs. The IgG specific antibodies were isolated by means of protein A-Sepharose CL-4B beads columns. IgG anti-A. simplex and -A. suum were coupled to CNBr-activated Sepharose 4B. For the purification of the larval A. simplex antigens, these were loaded into the anti-A. simplex column and bound antigens eluted. For the elimination of the epitopes responsible for the cross-reactions, the A. simplex specific proteins were loaded into the anti-A. suum column. To prove the specificity of the isolated proteins, immunochemical analyses by polyacrylamide gel electrophoresis were carried out. Further, we studied the different responses by ELISA to the different antigenic preparations of A. simplex used, observing their capability of discriminating among the different antisera raised in rabbits (anti-A. simplex, anti-A. suum, anti-T. canis). The discriminatory capability with the anti-T. canis antisera was good using the larval A. simplex crude extract (CE) antigen. When larval A. simplex CE antigen was loaded into a CNBr-activated Sepharose 4B coupled to IgG from rabbits immunized with A. simplex CE antigen, its capability for discriminate between A. simplex and A. suum was improved, increasing in the case of T. canis. The best results were obtained using larval A. simplex CE antigen loaded into a CNBr-activated Sepharose 4B coupled to IgG from rabbits immunized with adult A. suum CE antigen. When we compared the different serum dilution and antigenic concentration, we selected the working serum dilution of 1/400 and 1 µg/ml of antigenic concentration.

Predation Potential of the Water Bugs Sphaerodema rusticum on the Sewage Snails Physa acuta

The sewage snail Physa acuta is a serious threat to certain economic plants and to the purification plant of sewage works by rendering the biofilters ineffective. Various attempts are being made to control it. The efficacy of the predacious water bugs Sphaerodema rusticum was judged experimentally, in the laboratory in the potential control of P. acuta. It is revealed that, when supplied separately, the first, second and third instar and the adult S. rusticum did not attack P. acuta belonging to 3.1-8 mm, 5.1-8 mm, 7.1-8 mm and <= 3 mm size classes respectively. In the remaining trials predation rate varied from zero to eight (average 2.3) individuals per predator per day. In experiments with P. acuta belonging to all the size classes supplied together, none, except the first instar S. rusticum, attacked the prey individuals belonging to the lowest (<= 3 mm) size class. The first and second instar S. rusticum, in both trials did not attack P. acuta larger than 4 mm and 5 mm in shell length respectively. The water bugs belonging to the third, fourth, fifth instar and adult stages though preyed upon P. acuta with 3.1-8 mm shell length. The average rate of predation by a single S. rusticum varied from 0.14-3.08 individuals per day depending upon the size of P. acuta and the stage of S. rusticum. A single S. rusticum, irrespective of instar and adult stages, destroyed on average 4.16 P. acuta daily irrespective of sizes. It is estimated that one S. rusticum could destroy 1,360 P. acuta in its life time. The results clearly indicate that the water bug S. rusticum may be used to control the snails P. acuta.

Hépatite D:oubliée mais pas disparue [Hepatitis D: forgotten but not gone].

Hepatitis D virus (HDV) is a subviral agent which depends on the envelope proteins (HBsAg) of hepatitis B virus (HBV). Therefore, hepatitis D is observed only in patients infected with HBV. Chronic hepatitis D is the least frequent albeit most severe form of chronic viral hepatitis. A resurgence of chronic hepatitis D has been observed in Northern and Central Europe, mainly due to immigration of patients from regions with high prevalence. Every HBsAg-positive patient should be screened for concurrent HDV infection. Standard treatment consists of pegylated interferon-alpha for at least one year. Sustained virological response rates are approximately 20%. Liver transplantation should be considered in patients with advanced cirrhosis or limited hepatocellular carcinoma. Preventive measures for hepatitis D are the same as for hepatitis B.

The Bacillus subtilis Gne (GneA, GalE) protein can catalyse UDP-glucose as well as UDP-N-acetylglucosamine 4-epimerisation.

Mutations in the Bacillus subtilis gene that affect the activity of the uridine diphosphate (UDP)-N-acetylglucosamine (GlcNAc) 4-epimerase (EC 5.1.3.7) were shown to map to galE, the structural gene of the UDP-glucose (Glc) 4-epimerase (EC 5.1.3.2). This genetic evidence that the same enzyme can catalyse the epimerisation of hexoses as well as of their N-acetylated forms is confirmed by in vitro assays with purified enzyme. It appears that in B. subtilis, Gne (GneA, GalE) is involved in two distinct and essential functions, i.e., cell detoxification under certain growth conditions and the biosynthesis of anionic cell wall polymers. We discuss the evidence that such enzymes capable of utilizing both UDP-hexoses and UDP-N-acetylhexosamines are present in other organisms.

Rapid diagnostic tests for the home-based management of malaria, in a high-transmission area.

Rapid diagnostic tests (RDT) are sometimes recommended to improve the home-based management of malaria. The accuracy of an RDT for the detection of clinical malaria and the presence of malarial parasites has recently been evaluated in a high-transmission area of southern Mali. During the same study, the cost-effectiveness of a 'test-and-treat' strategy for the home-based management of malaria (based on an artemisinin-combination therapy) was compared with that of a 'treat-all' strategy. Overall, 301 patients, of all ages, each of whom had been considered a presumptive case of uncomplicated malaria by a village healthworker, were checked with a commercial RDT (Paracheck-Pf). The sensitivity, specificity, and positive and negative predictive values of this test, compared with the results of microscopy and two different definitions of clinical malaria, were then determined. The RDT was found to be 82.9% sensitive (with a 95% confidence interval of 78.0%-87.1%) and 78.9% (63.9%-89.7%) specific compared with the detection of parasites by microscopy. In the detection of clinical malaria, it was 95.2% (91.3%-97.6%) sensitive and 57.4% (48.2%-66.2%) specific compared with a general practitioner's diagnosis of the disease, and 100.0% (94.5%-100.0%) sensitive but only 30.2% (24.8%-36.2%) specific when compared against the fulfillment of the World Health Organization's (2003) research criteria for uncomplicated malaria. Among children aged 0-5 years, the cost of the 'test-and-treat' strategy, per episode, was about twice that of the 'treat-all' (U.S.$1.0. v. U.S.$0.5). In older subjects, however, the two strategies were equally costly (approximately U.S.$2/episode). In conclusion, for children aged 0-5 years in a high-transmission area of sub-Saharan Africa, use of the RDT was not cost-effective compared with the presumptive treatment of malaria with an ACT. In older patients, use of the RDT did not reduce costs. The question remains whether either of the strategies investigated can be made affordable for the affected population.

Efficacy of L-asparaginase with methotrexate and dexamethasone (AspaMetDex regimen) in patients with refractory or relapsing extranodal NK/T-cell lymphoma, a phase 2 study.

Extranodal NK/T-cell lymphoma, nasal type, is a rare and highly aggressive disease with a grim prognosis. No therapeutic strategy is currently identified in relapsing patients. We report the results of a French prospective phase II trial of an L-asparaginase-containing regimen in 19 patients with relapsed or refractory disease treated in 13 centers. Eleven patients were in relapse and 8 patients were refractory to their first line of treatment. L-Asparaginase-based treatment yielded objective responses in 14 of the 18 evaluable patients after 3 cycles. Eleven patients entered complete remission (61%), and only 4 of them relapsed. The median overall survival time was 1 year, with a median response duration of 12 months. The main adverse events were hepatitis, cytopenia, and allergy. The absence of antiasparaginase antibodies and the disappearance of Epstein-Barr virus serum DNA were significantly associated with a better outcome. These data confirm the excellent activity of L-asparaginase-containing regimens in extranodal NK/T-cell lymphoma. L-Asparaginase-based treatment should thus be considered for salvage therapy, especially in patients with disseminated disease. First-line L-asparaginase combination therapy for extranodal NK/T-cell lymphoma warrants evaluation in prospective trials. This trial is registered at www.clinicaltrials.gov as #NCT00283985.

Isoelectric focusing of alpha-1 acid glycoprotein (orosomucoid) in immobilized pH-gradients with 8M urea: detection of its desialylated variants using an alkaline phosphatase-linked secondary antibody system.

A method allowing a clear separation of the different variants of desialylated alpha 1-acid glycoprotein (orosomucoid) has been developed using isoelectric focusing in immobilized pH gradients, supplemented with 8 M urea and 2% v/v 2-mercaptoethanol. Immunoblotting with two antibody-steps afforded high sensitivity and permitted the detection of about 700 pg of alpha 1-acid glycoprotein in a 20 microL plasma sample diluted 1:28 672. A one year old bloodstrain, kept at room temperature, could easily be phenotyped.

Characteristics and origin of agates in sedimentary rocks from the Dryhead area, Montana, USA

Agates from the Bighorn district in Montana (USA), the so-called Dryhead area, and their adjacent host rocks have been examined in the present study. Analyses by XRD, polarizing microscopy, LA-ICP-MS, cathodoluminescence (CL), SEM and of oxygen isotopes were performed to obtain information surrounding the genesis of this agate type. Investigations of the agate microstructure by polarizing microscopy and CL showed that chalcedony layers and macrocrystalline quartz crystals may have formed by crystallization from the same silica source by a process of self-organization. High defect densities and internal structures (e. g. sector zoning) of quartz indicate that crystallization went rapidly under non-equilibrium conditions. Most trace-element contents in macrocrystalline quartz are less than in chalcedony due to a process of `self-purification', which also caused the formation of Fe oxide inclusions and spherules. Although the agates formed in sedimentary host rocks, analytical data indicate participation of hydrothermal fluids during agate formation. Trace elements (REE distribution patterns, U contents up to 70 ppm) and CL features of agate (transient blue CL), as well as associated minerals (fluorite, REE carbonates) point to the influence of hydrothermal processes on the genesis of the Dryhead agates. However, formation temperatures <120 degrees C were calculated from O-isotope compositions between 28.9 parts per thousand (quartz) and 32.2 parts per thousand (chalcedony).

In vitro antibacterial activity of a 7-O-beta-D-glucopyranosyl-nutanocoumarin from Chaptalia nutans (Asteraceae)

Ethanolic crude extracts from the roots of Chaptalia nutans, traditionally used in Brazilian folk medicine, were screened against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa by using the disk diffusion test technique. S. aureus with 14 mm inhibition zone was considered susceptible. E. coli and P. aeruginosa without such a zone were considered resistant. As a result of this finding, the ethanolic crude extract was fractionated on silica gel column chromatography into five fractions. The ethyl acetate fraction was active against S. aureus and Bacillus subtilis. Further column chromatography separation of the ethyl acetate fraction afforded 30 fractions, which were assayed against S. aureus. Fractions 16 and 17 showed inhibition zones with S. aureus, indicating the presence of active compounds, and were subjected to purification by repeated preparative thin layer chromatography. The pure compound 7-O-beta-D-glucopyranosyl-nutanocoumarin inhibited B. subtilis and S. aureus at concentrations of 62.5 µg/ml and 125 µg/ml, respectively. The antibacterial property of C. nutans appears to have justified its use for the treatment of wounds, which are contaminated through bacterial infections.

Gender differences in HIV progression to AIDS and death in industrialized countries: slower disease progression following HIV seroconversion in women.

To evaluate sex differences in human immunodeficiency virus (HIV) disease progression before (pre-1997) and after (1997-2006) introduction of highly active antiretroviral therapy, the authors used data from a collaboration of 23 HIV seroconverter cohort studies from Europe, Australia, and Canada restricted to the 6,923 seroconverters infected through injecting drug use and sex between men and women. Within a competing risk framework, they used Cox proportional hazards models allowing for late entry to evaluate sex differences in time from HIV seroconversion to death, to acquired immunodeficiency syndrome (AIDS), and to each first AIDS-defining disease and death without AIDS. While no significant sex differences were found before 1997, from 1997 onward, women had a lower risk of AIDS (adjusted cumulative relative risk (aCRR) = 0.76, 95% confidence interval (CI): 0.63, 0.90) and death (adjusted hazard ratio = 0.68, 95% CI: 0.56, 0.82) than men did. Compared with men, women also had lower risks of AIDS dementia complex (aCRR = 0.23, 95% CI: 0.07, 0.74), tuberculosis (aCRR = 0.60, 95% CI: 0.39, 0.92), Kaposi's sarcoma (aCRR = 0.27, 95% CI: 0.07, 0.99), lymphomas (aCRR = 0.47, 95% CI: 0.23, 0.96), and death without AIDS (aCRR = 0.74, 95% CI: 0.56, 0.98). Sex differences in HIV disease progression have become larger and statistically significant in the era of highly active antiretroviral therapy, supporting a stronger impact of health interventions among women.

CD4+ T cell count recovery in HIV type 1-infected patients is independent of class of antiretroviral therapy.

BACKGROUND: In recent years, treatment options for human immunodeficiency virus type 1 (HIV-1) infection have changed from nonboosted protease inhibitors (PIs) to nonnucleoside reverse-transcriptase inhibitors (NNRTIs) and boosted PI-based antiretroviral drug regimens, but the impact on immunological recovery remains uncertain. METHODS: During January 1996 through December 2004 [corrected] all patients in the Swiss HIV Cohort were included if they received the first combination antiretroviral therapy (cART) and had known baseline CD4(+) T cell counts and HIV-1 RNA values (n = 3293). For follow-up, we used the Swiss HIV Cohort Study database update of May 2007 [corrected] The mean (+/-SD) duration of follow-up was 26.8 +/- 20.5 months. The follow-up time was limited to the duration of the first cART. CD4(+) T cell recovery was analyzed in 3 different treatment groups: nonboosted PI, NNRTI, or boosted PI. The end point was the absolute increase of CD4(+) T cell count in the 3 treatment groups after the initiation of cART. RESULTS: Two thousand five hundred ninety individuals (78.7%) initiated a nonboosted-PI regimen, 452 (13.7%) initiated an NNRTI regimen, and 251 (7.6%) initiated a boosted-PI regimen. Absolute CD4(+) T cell count increases at 48 months were as follows: in the nonboosted-PI group, from 210 to 520 cells/muL; in the NNRTI group, from 220 to 475 cells/muL; and in the boosted-PI group, from 168 to 511 cells/muL. In a multivariate analysis, the treatment group did not affect the response of CD4(+) T cells; however, increased age, pretreatment with nucleoside reverse-transcriptase inhibitors, serological tests positive for hepatitis C virus, Centers for Disease Control and Prevention stage C infection, lower baseline CD4(+) T cell count, and lower baseline HIV-1 RNA level were risk factors for smaller increases in CD4(+) T cell count. CONCLUSION: CD4(+) T cell recovery was similar in patients receiving nonboosted PI-, NNRTI-, and boosted PI-based cART.

Positive and negative roles of the trans-acting T cell factor-1 for the acquisition of distinct Ly-49 MHC class I receptors by NK cells.

Members of the Ly-49 gene family code for class I MHC-specific receptors that regulate NK cell function. Due to a combinatorial distribution of Ly-49 receptors, NK cells display considerable clonal heterogeneity. The acquisition of one Ly-49 receptor, Ly-49A is strictly dependent on the transcriptional trans-acting factor T cell-specific factor-1 (TCF-1). Indeed, TCF-1 binds to two sites in the Ly-49a promoter and regulates its activity, suggesting that the Ly-49a gene is a direct TCF-1 target. TCF-1 deficiency resulted in the altered usage of additional Ly-49 receptors. We show in this study, using TCF-1 beta(2)-microglobulin double-deficient mice, that these repertoire alterations are not due to Ly-49/MHC class I interactions. Our findings rather suggest a TCF-1-dependent, cell autonomous effect on the acquisition of multiple Ly-49 receptors. Besides reduced receptor usage (Ly-49A and D), we also observed no effect (Ly-49C) and significantly expanded (Ly-49G and I) receptor usage in the absence of TCF-1. These effects did not in all cases correlate with the presence of TCF binding sites in the respective proximal promoter. Therefore, besides TCF-1 binding to the proximal promoter, Ly-49 acquisition may also be regulated by TCF-1 binding to more distant cis-acting elements and/or by regulating the expression of additional trans-acting factors. Consistent with the observed differential, positive or negative role of TCF-1 for Ly-49 receptor acquisition, reporter gene assays revealed the presence of an inducing as well as a repressing TCF site in certain proximal Ly-49 promoters. These findings reveal an important role of TCF-1 for the formation of the NK cell receptor repertoire.

Reduction in the proportion of fevers associated with Plasmodium falciparum parasitaemia in Africa: a systematic review.

BACKGROUND: Malaria is almost invariably ranked as the leading cause of morbidity and mortality in Africa. There is growing evidence of a decline in malaria transmission, morbidity and mortality over the last decades, especially so in East Africa. However, there is still doubt whether this decline is reflected in a reduction of the proportion of malaria among fevers. The objective of this systematic review was to estimate the change in the Proportion of Fevers associated with Plasmodium falciparum parasitaemia (PFPf) over the past 20 years in sub-Saharan Africa. METHODS: Search strategy. In December 2009, publications from the National Library of Medicine database were searched using the combination of 16 MeSH terms.Selection criteria. Inclusion criteria: studies 1) conducted in sub-Saharan Africa, 2) patients presenting with a syndrome of 'presumptive malaria', 3) numerators (number of parasitologically confirmed cases) and denominators (total number of presumptive malaria cases) available, 4) good quality microscopy.Data collection and analysis. The following variables were extracted: parasite presence/absence, total number of patients, age group, year, season, country and setting, clinical inclusion criteria. To assess the dynamic of PFPf over time, the median PFPf was compared between studies published in the years ≤2000 and > 2000. RESULTS: 39 studies conducted between 1986 and 2007 in 16 different African countries were included in the final analysis. When comparing data up to year 2000 (24 studies) with those afterwards (15 studies), there was a clear reduction in the median PFPf from 44% (IQR 31-58%; range 7-81%) to 22% (IQR 13-33%; range 2-77%). This dramatic decline is likely to reflect a true change since stratified analyses including explanatory variables were performed and median PFPfs were always lower after 2000 compared to before. CONCLUSIONS: There was a considerable reduction of the proportion of malaria among fevers over time in Africa. This decline provides evidence for the policy change from presumptive anti-malarial treatment of all children with fever to laboratory diagnosis and treatment upon result. This should insure appropriate care of non-malaria fevers and rationale use of anti-malarials.