Degradation of tyrosine and tryptophan residues of peptides by type I photosensitized oxidation

Pterin derivatives are involved in various biological functions, including enzymatic processes that take place in human skin. Unconjugated oxidized pterins are efficient photosensitizers under UV-A irradiation and accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder. These compounds are able to photoinduce the oxidation of the peptide α-melanocyte-stimulating hormone (α-MSH), which stimulates the production and release of melanin by melanocytes in skin and hair. In the present work we have used two peptides in which the amino acid sequence of α-MSH was mutated to specifically investigate the reactivity of tryptophan (Trp) and tyrosine residues (Tyr). The parent compound of oxidized pterins (Ptr) was used as a model photosensitizer in aqueous solution at pH 5.5 and was exposed to UV-A radiation, a wavelength range where the peptides do not absorb. Trp residue yields N-formylkynurenine and hydroxytryptophan as oxidized products, whereas the Tyr undergoes dimerization and incorporation of oxygen atoms. In both cases, the first step of the mechanism involves an electron transfer from the amino acid to the photosensitizer triplet excited state, Ptr is not consumed and hydrogen peroxide (H2O2) is released. The role of singlet oxygen produced by energy transfer from 3Ptr⁎ to dissolved O2 was negligible or minor. Other amino acid residues, such as histidine, might be also affected.Fil: Castaño Espinal, Diana Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vignoni, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vicendo, Patricia. Centre National de la Recherche Scientifique; Francia. Université Paul Sabatier; FranciaFil: Oliveros, Esther. Centre National de la Recherche Scientifique; Francia. Université Paul Sabatier; FranciaFil: Thomas, Andrés Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Leptospirosis in Rio Grande do Sul, Brazil: An Ecosystem Approach in the Animal-Human Interface

<div><p>Background</p><p>Leptospirosis is an epidemic-prone neglected disease that affects humans and animals, mostly in vulnerable populations. The One Health approach is a recommended strategy to identify drivers of the disease and plan for its prevention and control. In that context, the aim of this study was to analyze the distribution of human cases of leptospirosis in the State of Rio Grande do Sul, Brazil, and to explore possible drivers. Additionally, it sought to provide further evidence to support interventions and to identify hypotheses for new research at the human-animal-ecosystem interface.</p><p>Methodology and findings</p><p>The risk for human infection was described in relation to environmental, socioeconomic, and livestock variables. This ecological study used aggregated data by municipality (all 496). Data were extracted from secondary, publicly available sources. Thematic maps were constructed and univariate analysis performed for all variables. Negative binomial regression was used for multivariable statistical analysis of leptospirosis cases. An annual average of 428 human cases of leptospirosis was reported in the state from 2008 to 2012. The cumulative incidence in rural populations was eight times higher than in urban populations. Variables significantly associated with leptospirosis cases in the final model were: Parana/Paraiba ecoregion (RR: 2.25; CI_95%: 2.03–2.49); Neossolo Litolítico soil (RR: 1.93; CI_95%: 1.26–2.96); and, to a lesser extent, the production of tobacco (RR: 1.10; CI_95%: 1.09–1.11) and rice (RR: 1.003; CI_95%: 1.002–1.04).</p><p>Conclusion</p><p>Urban cases were concentrated in the capital and rural cases in a specific ecoregion. The major drivers identified in this study were related to environmental and production processes that are permanent features of the state. This study contributes to the basic knowledge on leptospirosis distribution and drivers in the state and encourages a comprehensive approach to address the disease in the animal-human-ecosystem interface.</p></div

PI3K oncogenic mutations mediate resistance to afatinib in HER2/neu overexpressing gynecological cancers

Aberrant expression of HER2/neu and PIK3CA gene products secondary to amplification/mutations are common in high-grade-serous-endometrial (USC) and ovarian-cancers (HGSOC). Because scant information is currently available in the literature on the potential negative effect of PIK3CA mutations on the activity of afatinib, in this study we evaluate for the first time the role of oncogenic PIK3CA mutations as a potential mechanism of resistance to afatinib in HGSOC and USC overexpressing HER2/neu. We used six whole-exome-sequenced primary HGSOC/USC cell-lines and three xenografts overexpressing HER2/neu and harboring mutated or wild-type PIK3CA/PIK3R1 genes to evaluate the role of PI3K-mutations as potential mechanism of resistance to afatinib, an FDA-approved pan-c-erb-inhibitor in clinical trials in USC. Primary-USC harboring wild-type-PIK3CA gene was transfected with plasmids encoding oncogenic PIK3CA-mutations (H1047R/E545K). The effect of afatinib on HER2/PI3K/AKT/mTOR pathway was evaluated by immunoblotting. We found PI3K wild-type cell-lines to be significantly more sensitive (lower IC50) than PI3K-mutated cell-lines p = 0.004). In vivo, xenografts of primary cell-line USC-ARK2, transfected with the PIK3CA-H1047R or E545K hotspot-mutations, exhibited significantly more rapid tumor growth when treated with afatinib, compared to mice harboring ARK2-tumors transfected with wild-type-PIK3CA (p = 0.041 and 0.001, respectively). By western-blot, afatinib effectively reduced total and phospho-HER2 proteins in all cell-lines. However, H1047R/E545K-PIK3CA-transfected-ARK2-cells demonstrated a greater compensatory increase in phosphorylated-AKT proteins after afatinib exposure when compared to controls ARK2. Oncogenic PI3K mutations may represent a major mechanism of resistance to afatinib. Combinations of c-erb with PIK3CA, AKT or mTOR inhibitors may be necessary to more efficiently block the PIK3CA/AKT/mTOR pathway. •Oncogenic PI3K mutations may represent a novel and major mechanism of resistance to single agent afatinib.•Combinations of c-erb with PIK3CA, AKT or mTOR inhibitors may be necessary to block the PIK3CA pathway in gynecologic tumors.•PIK3CA/PIK3R1oncogenic mutations may represent a biomarker able to identify patients resistant to single agent afatinib

Human cases of leptospirosis by area of residence, Rio Grande do Sul, 2008–2012.

<p>*Relative to the total during the 5 years</p><p>Source: SINAM, Ministry of Health of Brazil.</p><p>Human cases of leptospirosis by area of residence, Rio Grande do Sul, 2008–2012.</p

Possible drivers and leptospirosis cases per municipalities (P<0.15 in the univariable and multivariable analysis and P<0.05), Rio Grande do Sul, 2008–2012.

<p>^a Variables were dichotomized as minority (was considered when covering land or proportional were less then 50% of the municipality) majority (was considered when covering land or proportional were above 50.01% of the municipality</p><p>^b Estimates for rice and tobacco are presented on the increase of one unit on count cases per 10.000 tons.</p><p>^c Variable was dichotomized as minority (considered when the less then 50% of municipality’s properties had up to 10 animals) majority (when more then 50.1% of municipality’s properties had up to 10 animals)</p><p>Possible drivers and leptospirosis cases per municipalities (P<0.15 in the univariable and multivariable analysis and P<0.05), Rio Grande do Sul, 2008–2012.</p

Cumulative incidence of leptospirosis (10,000 habitants), by municipality, Rio Grande do Sul, 2008–2012.

<p>Cumulative incidence of leptospirosis (10,000 habitants), by municipality, Rio Grande do Sul, 2008–2012.</p

Cumulative incidence for leptospirosis type of soil and neossole type, by municipality Rio Grande do Sul, 2008–2012.

<p>Cumulative incidence for leptospirosis type of soil and neossole type, by municipality Rio Grande do Sul, 2008–2012.</p