Exome array analysis of adverse reactions to fluoropyrimidine-based therapy for gastrointestinal cancer.

Fluoropyrimidines, including 5-fluororacil (5FU) and its pro-drug Capecitabine, are the common treatment for colorectal, breast, neck and head cancers-either as monotherapy or in combination therapy. Adverse reactions (ADRs) to the treatment are common and often result in treatment discontinuation or dose reduction. Factors contributing to ADRs, including genetic variation, are poorly characterized. We performed exome array analysis to identify genetic variants that contribute to adverse reactions. Our final dataset consisted of 504 European ancestry individuals undergoing fluoropyrimidine-based therapy for gastrointestinal cancer. A subset of 254 of these were treated with Capecitabine. All individuals were genotyped on the Illumina HumanExome Array. Firstly, we performed SNP and gene-level analyses of protein-altering variants on the array to identify novel associations the following ADRs, which were grouped into four phenotypes based on symptoms of diarrhea, mucositis, and neutropenia and hand-and-foot syndrome. Secondly, we performed detailed analyses of the HLA region on the same phenotypes after imputing the HLA alleles and amino acids. No protein-altering variants, or sets of protein-altering variants collapsed into genes, were associated with the main outcomes after Bonferroni correction. We found evidence that the HLA region was enriched for associations with Hand-and-Foot syndrome (p = 0.023), but no specific SNPs or HLA alleles were significant after Bonferroni correction. Larger studies will be required to characterize the genetic contribution to ADRs to 5FU. Future studies that focus on the HLA region are likely to be fruitful.

Experiencia clínica con el uso del monitor cardiaco Implantable / Clinical experience with the use of an implantable cardiac monitor

Resumen Objetivos: Describir la experiencia con el uso del monitor cardiaco implantable determinando: el diagnóstico final encontrado y el tiempo para alcanzarlo, proporción de pacientes con la etiología aclarada y el tratamiento instaurado. Metodología: Estudio observacional retrospectivo. Resultados: Ciento ocho (108) monitores explantados de un total de 150 implantados entre los años 2009 a 2015, fueron analizados. Un diagnóstico electrocardiográfico concordante con el síntoma fue encontrado en el 71,7% de aquellos con síncope, siendo la principal causa la bradicardia sinusal extrema y/o arresto sinusal. El rendimiento diagnóstico para aquellos investigados por palpitaciones recurrentes o sospecha de arritmias supraventriculares o ventriculares fue del 29% siendo la causa más frecuente la fibrilación auricular. Un 50% de los diagnósticos se alcanzaron tras una monitoría entre 12 y 36 meses. El marcapasos fue el tratamiento más frecuente para los pacientes con síncope y la ablación por radiofrecuencia para aquellos con palpitaciones. En cuanto a la seguridad, no se presentaron eventos adversos mayores con el implante del monitor. Conclusiones: El monitor cardiaco implantable mostró un adecuado rendimiento diagnóstico para la identificación de las alteraciones electrocardiográficas en los pacientes con síncope. Es necesario realizar más estudios para dilucidar su papel en el estudio de las palpitaciones.

Abstract Motivation: To describe the experience of the use of an implantable cardiac monitor and analysing the final diagnosis and the time to reach it, the proportion of patients with clear aetiology and existing treatment. Methods: Retrospective observational study. Results: One hundred and eight (108) monitors explanted out of a total of 150 implanted patients between 2009 and 2015 were analysed. An electrocardiographic diagnosis matching the symptom was found in 71.7% of those with syncope, being the main cause for extreme sinus bradicardia and/or sinus arrest. Efficiency of the diagnosis for those investigated due to recurrent palpitations or suspicion of supraventricular or ventricular arrhythmias was of 29%, being the main cause of atrial fibrillation. 50% of the diagnoses were reached after monitorisation between 12 and 36 months. Pacemakers were the most frequent treatment for patients with syncope and radiofrequency ablation for those with palpitations. Regarding security, no major adverse events were found when implanting the monitor. Conclusion: The implantable cardiac monitor showed an adequate efficiency of diagnosis for the identification of electrocardiographic alterations in patients with syncope. More studies are required in order to elucidate its role in the study of palpitations.

Structural and mechanistic basis of zinc regulation across the E. coli Zur regulon.

Commensal microbes, whether they are beneficial or pathogenic, are sensitive to host processes that starve or swamp the prokaryote with large fluctuations in local zinc concentration. To understand how microorganisms coordinate a dynamic response to changes in zinc availability at the molecular level, we evaluated the molecular mechanism of the zinc-sensing zinc uptake regulator (Zur) protein at each of the known Zur-regulated genes in Escherichia coli. We solved the structure of zinc-loaded Zur bound to the P(znuABC) promoter and show that this metalloregulatory protein represses gene expression by a highly cooperative binding of two adjacent dimers to essentially encircle the core element of each of the Zur-regulated promoters. Cooperativity in these protein-DNA interactions requires a pair of asymmetric salt bridges between Arg52 and Asp49' that connect otherwise independent dimers. Analysis of the protein-DNA interface led to the discovery of a new member of the Zur-regulon: pliG. We demonstrate this gene is directly regulated by Zur in a zinc responsive manner. The pliG promoter forms stable complexes with either one or two Zur dimers with significantly less protein-DNA cooperativity than observed at other Zur regulon promoters. Comparison of the in vitro Zur-DNA binding affinity at each of four Zur-regulon promoters reveals ca. 10,000-fold variation Zur-DNA binding constants. The degree of Zur repression observed in vivo by comparison of transcript copy number in wild-type and Δzur strains parallels this trend spanning a 100-fold difference. We conclude that the number of ferric uptake regulator (Fur)-family dimers that bind within any given promoter varies significantly and that the thermodynamic profile of the Zur-DNA interactions directly correlates with the physiological response at different promoters.

Tetrathiomolybdate inhibits copper trafficking proteins through metal cluster formation.

Tetrathiomolybdate (TM) is an orally active agent for treatment of disorders of copper metabolism. Here we describe how TM inhibits proteins that regulate copper physiology. Crystallographic results reveal that the surprising stability of the drug complex with the metallochaperone Atx1 arises from formation of a sulfur-bridged copper-molybdenum cluster reminiscent of those found in molybdenum and iron sulfur proteins. Spectroscopic studies indicate that this cluster is stable in solution and corresponds to physiological clusters isolated from TM-treated Wilson's disease animal models. Finally, mechanistic studies show that the drug-metallochaperone inhibits metal transfer functions between copper-trafficking proteins. The results are consistent with a model wherein TM can directly and reversibly down-regulate copper delivery to secreted metalloenzymes and suggest that proteins involved in metal regulation might be fruitful drug targets.