Synthetically induced Arabidopsis thaliana autotetraploids provide insights into the analysis of meiotic mutants with altered crossover frequency.

Mutations affecting crossover (CO) frequency and distribution lead to the presence of univalents during meiosis, giving rise to aneuploid gametes and sterility. These mutations may have a different effect after chromosome doubling. The combination of altered ploidy and mutations could be potentially useful to gain new insights into the mechanisms and regulation of meiotic recombination; however, studies using autopolyploid meiotic mutants are scarce. Here, we have analyzed the cytogenetic consequences in colchicine-induced autotetraploids (colchiploids) from different Arabidopsis mutants with an altered CO frequency. We have found that there are three types of mutants: mutants in which chiasma frequency is doubled after chromosome duplication (zip4, mus81), as in the control; mutants in which polyploidy leads to a higher-than-expected increase in chiasma frequency (asy1, mer3, hei10, and mlh3); and mutants in which the rise in chiasma frequency produced by the presence of two extrachromosomal sets is less than doubled (msh5, fancm). In addition, the proportion of class I/class II COs varies after chromosome duplication in the control. The results obtained reveal the potential of colchiploid meiotic mutants for better understanding of the function of key proteins during plant meiosis. This is especially relevant considering that most crops are polyploids.

Partial cytological diploidization of neoautotetraploid meiosis by induced cross-over rate reduction.

Polyploids, which arise from whole-genome duplication events, have contributed to genome evolution throughout eukaryotes. Among plants, novel features of neopolyploids include traits that can be evolutionarily or agriculturally beneficial, such as increased abiotic stress tolerance. Thus, in addition to being interesting from an evolutionary perspective, genome duplication is also increasingly recognized as a promising crop improvement tool. However, newly formed (neo)polyploids commonly suffer from fertility problems, which have been attributed to abnormal associations among the multiple homologous chromosome copies during meiosis (multivalents). Here, we test the long-standing hypothesis that reducing meiotic cross-over number may be sufficient to limit multivalent formation, favoring diploid-like bivalent associations (cytological diploidization). To do so, we developed Arabidopsis thaliana lines with low cross-over rates by combining mutations for HEI10 and TAF4b. Double mutants showed a reduction of ~33% in cross-over numbers in diploids without compromising meiotic stability. Neopolyploids derived from the double mutant show a cross-over rate reduction of about 40% relative to wild-type neotetraploids, and groups of four homologs indeed formed fewer multivalents and more bivalents. However, we also show that the reduction in multivalents comes with the cost of a slightly increased frequency of univalents and that it does not rescue neopolyploid fertility. Thus, while our results do show that reducing cross-over rates can reduce multivalent frequency in neopolyploids, they also emphasize that there are additional factors affecting both meiotic stability and neopolyploid fertility that will need to be considered in solving the neopolyploid fertility challenge.

Isolated axillary nerve palsy after liposuction, an exceptional complication.

Isolated injury to the axillary nerve associated with the patient's surgical position is a very rare complication, and in most cases it is associated with the prone during spinal surgery. The presentation of this pathology in relation to surgeries of another nature is exceptional, with only a few cases in the scientific literature. We present the case of a patient who developed symptoms of isolated left axillary nerve palsy after undergoing lipoabdominoplasty and breast reduction, in which the prone and supine positions were alternated. The use of an infiltration solution with lidocaine and epinephrine could have contributed to the appearance of the lesion in this unique case. Finally, the clinical picture was fully resolved thanks to conservative treatment.

Late seroma of the breast in association with COVID-19 infection: two case reports.

The SARS-CoV-2 pandemic is giving rise to a wide range of clinical manifestations, which can affect all organs and systems. Due to the enormous and constantly growing number of infected people, even the rarest complications will be observed in a very high number of patients. Late periprosthetic seroma of the breast has gained importance since the description of Breast Implant Associated Anaplastic Large Cell Lymphoma (BIA-ALCL), but this entity is not the  only cause. Among the causes of non-BIA-ALCL late seroma, we can include those of mechanical origin and those of non-mechanical origin. Within the latter, the common denominator is the triggering of an aberrant immune reaction that generates an inflammatory exudate from the periprosthetic capsule that gives rise to the seroma. We present two cases of late breast seroma as a manifestation of SARS-CoV-2 infection. Level of evidence: Level V, diagnostic study.

Clinical, genetic and pharmacological data support targeting the MEK5/ERK5 module in lung cancer.

Despite advances in its treatment, lung cancer still represents the most common and lethal tumor. Because of that, efforts to decipher the pathophysiological actors that may promote lung tumor generation/progression are being made, with the final aim of establishing new therapeutic options. Using a transgenic mouse model, we formerly demonstrated that the sole activation of the MEK5/ERK5 MAPK route had a pathophysiological role in the onset of lung adenocarcinomas. Given the prevalence of that disease and its frequent dismal prognosis, our findings opened the possibility of targeting the MEK5/ERK5 route with therapeutic purposes. Here we have explored such possibility. We found that increased levels of MEK5/ERK5 correlated with poor patient prognosis in lung cancer. Moreover, using genetic as well as pharmacological tools, we show that targeting the MEK5/ERK5 route is therapeutically effective in lung cancer. Not only genetic disruption of ERK5 by CRISPR/Cas9 caused a relevant inhibition of tumor growth in vitro and in vivo; such ERK5 deficit augmented the antitumoral effect of agents normally used in the lung cancer clinic. The clinical correlation studies together with the pharmacological and genetic results establish the basis for considering the targeting of the MEK5/ERK5 route in the therapy for lung cancer.

Isolated axillary nerve palsy after liposuction, an exceptional complication. / Parálisis aislada del nervio axilar tras liposucción, una complicación excepcional.

Isolated injury to the axillary nerve associated with the patient́s surgical position is a very rare complication, and in most cases it is associated with the prone during spinal surgery. The presentation of this pathology in relation to surgeries of another nature is exceptional, with only a few cases in the scientific literature. We present the case of a patient who developed symptoms of isolated left axillary nerve palsy after undergoing lipoabdominoplasty and breast reduction, in which the prone and supine positions were alternated. The use of an infiltration solution with lidocaine and epinephrine could have contributed to the appearance of the lesion in this unique case. Finally, the clinical picture was fully resolved thanks to conservative treatment.

Citation Classics in Consumer Neuroscience, Neuromarketing and Neuroaesthetics: Identification and Conceptual Analysis.

Neuromarketing, consumer neuroscience and neuroaesthetics are a broad research area of neuroscience with an extensive background in scientific publications. Thus, the present study aims to identify the highly cited papers (HCPs) in this research field, to deliver a summary of the academic work produced during the last decade in this area, and to show patterns, features, and trends that define the past, present, and future of this specific area of knowledge. The HCPs show a perspective of those documents that, historically, have attracted great interest from a research community and that could be considered as the basis of the research field. In this study, we retrieved 907 documents and analyzed, through H-Classics methodology, 50 HCPs identified in the Web of Science (WoS) during the period 2010-2019. The H-Classic approach offers an objective method to identify core knowledge in neuroscience disciplines such as neuromarketing, consumer neuroscience, and neuroaesthetics. To accomplish this study, we used Bibliometrix R Package and SciMAT software. This analysis provides results that give us a useful insight into the development of this field of research, revealing those scientific actors who have made the greatest contribution to its development: authors, institutions, sources, countries as well as documents and references.

Enfermedad de Dieterich: reporte de un caso de una enfermedad muy poco frecuente / Dieterich's disease: a case report of a very rare disease

RESUMEN La enfermedad de Dieterich o necrosis avascular de la cabeza de los metacarpianos es una enfermedad muy poco frecuente, con poco más de 50 casos reportados en la literatura. De etiología desconocida, clínicamente se puede manifestar de forma variable, desde asintomática hasta con evidente inflamación y limitación funcional dolorosa de la articulación metacarpofalángica afectada. Presentamos el caso de un paciente de 82 anos que presentaba dolor a nivel de la articulación metacarpofalángica del tercer dedo de la mano derecha, de un año de evolución, sin causa aparente. La exploración física no evidenciaba limitación funcional, ni dolor; tampoco se objetivó eritema, tumefacción o efecto masa. Se realizó un estudio radiológico con diagnóstico de enfermedad de Dieterich avanzada, estableciendo tratamiento conservador con antiinflamatorios no esteroideos con mejoría clínica significativa.

ABSTRACT Dieterich's disease, or avascular necrosis of the metacarpal head, is a very rare disease, with just over 50 cases reported in the literature. Of unknown aetiology, it can manifest clinically in a variable way, from asymptomatic to obvious inflammation and painful functional limitation of the affected metacarpophalangeal joint. The case is presented of an 82-yearold patient who presented with pain at the level of the metacarpophalangeal joint of the third finger of the right hand of 1 year of duration without apparent cause. The physical examination showed no functional limitation or pain. Furthermore, no erythema, swelling, or mass effect was observed. A radiological study was carried out, leading to a diagnosis of advanced Dieterich's disease. Conservative treatment was started with nonsteroidal anti-inflammatory drugs, with a significant clinical improvement.

Characterizing Highly Cited Papers in Mass Cytometry through H-Classics.

Mass cytometry (CyTOF) is a relatively novel technique for the multiparametric analysis of single-cell features with an increasing central role in cell biology, immunology, pharmacology, and biomedicine. This technique mixes the fundamentals of flow cytometry with mass spectrometry and is mainly used for in-depth studies of the immune system and diseases with a significant immune load, such as cancer, autoimmune diseases, and viral diseases like HIV or the recently emerged COVID-19, produced by the SARS-CoV-2 coronavirus. The objective of this study was to provide a useful insight into the evolution of the mass cytometry research field, revealing the knowledge structure (conceptual and social) and authors, countries, sources, documents, and organizations that have made the most significant contribution to its development. We retrieved 937 articles from the Web of Science (2010-2019), analysed 71 Highly Cited Papers (HCP) through the H-Classics methodology and computed the data by using Bibliometrix R package. HCP sources corresponded to high-impact journals, such as Nature Biotechnology and Cell, and its production was concentrated in the US, and specifically Stanford University, affiliation of the most relevant authors in the field. HCPs analysis confirmed great interest in the study of the immune system and complex data processing in the mass cytometry research field.

An inducible ectopic expression system of EWSR1-FLI1 as a tool for understanding Ewing sarcoma oncogenesis.

The presence of the chimeric EWSR1-FLI1 oncoprotein is the main and initiating event defining Ewing sarcoma (ES). The dysregulation of epigenomic and proteomic homeostasis induced by the oncoprotein contributes to a wide variety of events involved in oncogenesis and tumor progression. Attempts at studying the effects of EWSR1-FLI1 in non-tumor cells to understand the mechanisms underlying sarcomagenesis have been unsuccessful to date, as ectopic expression of EWSR1-FLI1 blocks cell cycle progression and induces apoptosis in the tested cell lines. Therefore, it is essential to find a permissive cell type for EWSR1-FLI1 expression that allows its endogenous molecular functions to be studied. Here we have demonstrated that HeLa cell lines are permissive to EWSR1-FLI1 ectopic expression, and that our model substantially recapitulates the endogenous activity of the EWSR1-FLI1 fusion protein. This model could contribute to better understanding ES sarcomagenesis by helping to understand the molecular mechanisms induced by the EWSR1-FLI1 oncoprotein.

Hippo pathway effectors YAP1/TAZ induce an EWS-FLI1-opposing gene signature and associate with disease progression in Ewing sarcoma.

YAP1 and TAZ (WWTR1) oncoproteins are the final transducers of the Hippo tumor suppressor pathway. Deregulation of the pathway leads to YAP1/TAZ activation fostering tumorigenesis in multiple malignant tumor types, including sarcoma. However, oncogenic mutations within the core components of the Hippo pathway are uncommon. Ewing sarcoma (EwS), a pediatric cancer with low mutation rate, is characterized by a canonical fusion involving the gene EWSR1 and FLI1 as the most common partner. The fusion protein is a potent driver of oncogenesis, but secondary alterations are scarce, and little is known about other biological factors that determine the risk of relapse or progression. We have observed YAP1/TAZ expression and transcriptional activity in EwS cell lines. Analyses of 55 primary human EwS samples revealed that high YAP1/TAZ expression was associated with progression of the disease and predicted poorer outcome. We did not observe recurrent SNV or copy number gains/losses in Hippo pathway-related loci. However, differential CpG methylation of the RASSF1 locus (a regulator of the Hippo pathway) was observed in EwS cell lines compared with mesenchymal stem cells, the putative cell of origin of EwS. Hypermethylation of RASSF1 correlated with the transcriptional silencing of the tumor suppressor isoform RASFF1A, and transcriptional activation of the pro-tumorigenic isoform RASSF1C, which promotes YAP1/TAZ activation. Knockdown of YAP1/TAZ decreased proliferation and invasion abilities of EwS cells and revealed that YAP1/TAZ transcription activity is inversely correlated with the EWS-FLI1 transcriptional signature. This transcriptional antagonism could be explained partly by EWS-FLI1-mediated transcriptional repression of TAZ. Thus, YAP1/TAZ may override the transcriptional program induced by the fusion protein, contributing to the phenotypic plasticity determined by dynamic fluctuation of the fusion protein, a recently proposed model for disease dissemination in EwS. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

How to Perform an Accurate Analysis of Metaphase I Chromosome Configurations in Autopolyploids of Arabidopsis thaliana.

During meiosis, accurate segregation of chromosomes requires the formation of bivalents at metaphase I. In autopolyploids, there are more than two copies of each chromosome with the same chance to form chiasmata at meiosis. This leads to the formation of multivalent configurations in which chiasma quantification is rather complicated. Here, we present an improved cytological protocol, including fluorescence in situ hybridization, to obtain high quality spreads of metaphase I chromosomes from Arabidopsis thaliana autotetraploids. This method allows an accurate analysis of the different meiotic configurations and enables the assessment of the number of chiasmata formed by each tetrasome (group of four homologs).

The combination of epigenetic drugs SAHA and HCI-2509 synergistically inhibits EWS-FLI1 and tumor growth in Ewing sarcoma.

PURPOSE: Epigenetic regulation is crucial in mammalian development and maintenance of tissue-cell specific functions. Perturbation of epigenetic balance may lead to alterations in gene expression, resulting in cellular transformation and malignancy. Previous studies in Ewing sarcoma (ES) have shown that the Nucleosome Remodeling Deacetylase (NuRD) complex binds directly to EWS-FLI1 oncoprotein and modulates its transcriptional activity. The role of EWS-FLI1 as a driver of proliferation and transformation in ES is widely known, but the effect of epigenetic drugs on fusion activity remains poorly described. The present study evaluated the combination effects of the histone deacetylases inhibitor suberoylanilide hydroxamic acid (SAHA) and Lysine-specific demethylase1 inhibitor (HCI-2509) on different biological functions in ES and in comparison to monotherapy treatments. RESULTS: The study of proliferation and cell viability showed a synergistic effect in most ES cell lines analyzed. An enhanced effect was also observed in the induction of apoptosis, together with accumulation of cells in G1 phase and a blockage of the migratory capacity of ES cell lines. Treatment, either in monotherapy or in combination, caused a significant decrease of EWS-FLI1 mRNA and protein levels and this effect is mediated in part by fusion gene promoter regulation. The anti-tumor effect of this combination was confirmed in patient-derived xenograft mouse models, in which only the combination treatment led to a statistically significant decrease in tumor volume. CONCLUSIONS: The combination of SAHA and HCI-2509 is proposed as a novel treatment strategy for ES patients to inhibit the essential driver of this sarcoma and tumor growth.

Competition for Chiasma Formation Between Identical and Homologous (But Not Identical) Chromosomes in Synthetic Autotetraploids of Arabidopsis thaliana.

Polyploid organisms provide additional opportunities to study meiosis in a more complex context since more than two potential homologous chromosomes are available. When the chromosome complement of a diploid individual is duplicated, each chromosome is accompanied by one identical and two homologous chromosomes within the same nucleus. In this situation, a competition in pairing/synapsis/chiasma formation between identical and homologous (but not necessarily identical) chromosomes can occur. Several studies have been conducted in different species to address whether there are preferences in crossover formation between identical rather than homologous chromosomes. In this study, multivalent and chiasma frequencies were cytologically analyzed in synthetic autotetraploids of Arabidopsis thaliana including the accessions Col, Ler, and the Col/Ler hybrid. Fluorescence in situ hybridization was conducted to identify each chromosome at metaphase I. The new Col and Ler tetraploids showed high multivalent frequencies, exceeding the theoretical 66.66% expected on a simple random end-pairing model, thus indicating that there are more than two autonomous synaptic sites per chromosome despite their small size. However, a significant excess of bivalent pairs was found in the Col/Ler hybrid, mainly due to the contribution of chromosomes 2 and 3. The mean chiasma frequencies of the three artificial autotetraploids were about twofold the corresponding mean cell chiasma frequencies of their diploid counterparts. The relative contribution of each chromosome to the total chiasma frequency was similar in the three genotypes, with the exception of a lower contribution of chromosome 3 in the hybrid. Preferences for chiasma formation between identical and homologous chromosomes were analyzed in Col/Ler 4x, taking advantage of the cytological differences between the accessions: variations in the size of the 45S rDNA region on the short arm of chromosome 2 and changes in the size and localization of the 5S rDNA region in chromosome 3. We observed a different behavior of chromosomes 2 and 3, i.e., random chiasma formation between identical and homologous chromosomes 2, and preferences for chiasma formation between homologous chromosomes 3. Hence, our results reveal the existence of chromosome-specific mechanisms responsible for these preferences.

Preclinical evaluation of anti-Helicobacter spp. activity of Hippocratea celastroides Kunth and its acute and sub-acute toxicity.

BACKGROUND: Hippocratea celastroides Kunth, commonly known as "cancerina", is used in Mexican Traditional Medicine for the treatment of gastric and intestinal infections, systemic and skin inflammation, injuries and gastritis. The aim of this research was to assess the anti-Helicobacter pylori activities of hydro-ethanolic root-bark extracts from Hippocratea celastroides Kunth in naturally infected dogs, after testing their acute and subacute toxicities in mice. METHODS: To determine in vivo acute toxicity, a hydro-ethanolic extract was obtained and administered orally in female and male Balb-C mice, at doses ranging from 2000 to 5000 mg/kg. For the subacute study, a hydro-ethanolic extract was given to male and female Balb-C mice at doses ranging from 200 to 2000 mg/kg body weight. The animals were observed daily over a period of 42 days for signs of toxicity. In the pre-clinical anti-Helicobacter spp. assay, 60 dogs were included. Eighteen and 19 dogs for the experimental and control groups respectively, concluded the study. The experimental treatment consisted of H. celastroides hydro-ethanolic extract and the control treatment of amoxicillin-clarithromycin-omeprazole. RESULTS: Oral LD50 (lethal dose 50) values for hydro-ethanolic extract were indeterminable at the highest tested doses. Under the subacute administration, neither mortality nor any sign of toxicity were observed when the hydro-ethanolic extract was administered. There were no significant alterations in biochemical parameters. The prevalence of Helicobacter spp. infection in dogs was 97.1 % for the experimental group and 100 % for the control group. Effectiveness was of 33.3 and 55 % in the experimental and control group respectively. The oral administration of H. celastroides was well-tolerated and safe. CONCLUSION: The root-bark of H. celastroides produced no signs of toxicity, and manifested pharmacological activity that indicated the possibility of an alternative treatment for H. pylori infection. Effectiveness is still low so it is necessary to continue research.

[Results of provisional use of a system for voluntary anonymous reporting of incidents that threaten patient safety in the emergency medical services of Asturias]. / Resultados de la instauración provisional de un sistema voluntario y anónimo de notificación de incidentes en seguridad del paciente en el SAMU de Asturias.

OBJECTIVES: To describe the reported incidents and adverse events in the emergency medical services of Asturias, Spain, and assess their consequences, delays caused, and preventability. MATERIAL AND METHODS: Prospective, observational study of incidents reported by the staff of the emergency medical services of Asturias after implementation of a system devised by the researchers. RESULTS: Incident reports were received for 0.48% (95% CI, 0.41%-0.54%) of the emergencies attended. Patient safety was compromised in 74.7% of the reported incidents. Problems arising in the emergency response coordination center (ERCC) accounted for 37.6% of the incidents, transport problems for 13.4%, vehicular problems for 10.8%, and communication problems for 8.8%. Seventy percent of the reported incidents caused delays in care; 55% of the reported incidents that put patients at risk (according to severity assessment code ratings) corresponded to problems related to human or material resources. A total of 88.1% of the incidents reported were considered avoidable. Some type of intervention was required to attenuate the effects of 46.2% of the adverse events reported. The measures that staff members most often proposed to prevent adverse events were to increase human and material resources (28.3%), establish protocols (14.5%), and comply with quality of care recommendations (9.7%). CONCLUSION: It is important to promote a culture of safety and incident reporting among health care staff in Asturias given the number of serious adverse events. Reporting is necessary for understanding the errors made and taking steps to prevent them. The ERCC is the point in the system where incidents are particularly likely to appear and be noticed and reported.

OBJETIVO: Conocer los incidentes y eventos adversos (EA) que se notificaron en el Servicio de Atención Médica Urgente (SAMU) de Asturias y caracterizarlos, evaluando sus consecuencias, el retraso asistencial provocado y su evitabilidad. METODO: Estudio observacional y prospectivo en el que se analizaron las notificaciones realizadas por los profesionales sanitarios del SAMU Asturias, en un sistema de notificación diseñado por los investigadores. RESULTADOS: Se obtuvo una tasa de notificación de 0,5% (IC 95%: 0,41-0,54). Un 74,7% supusieron daño al paciente. El 37,6% de los problemas estuvo relacionado con el centro coordinador de urgencias (CCU), 13,4% con el transporte, 10,8% con el vehículo y 8,8% con problemas de comunicación. Un 70% de los sucesos adversos (SA) notificados conllevó un retraso en la asistencia sanitaria. Un 55% de las notificaciones del CCU en las que hubo riesgo SAC (Severity Assessment Code) correspondió a problemas de recursos humanos y materiales. Los notificantes consideraron que un 88,1% eran evitables. Un 46,2% de los EA precisaron algún tipo de intervención para paliar sus efectos. Las medidas más propuestas por los profesionales para evitar los EA fueron aumento de recursos humanos y materiales (28,3%), elaboración de protocolos (14,5%) y cumplimiento de criterios de calidad (9,7%). CONCLUSIONES: Fomentar la cultura de seguridad y la notificación de los profesionales sanitarios es de especial importancia en nuestro medio, por el número de EA graves, para así conocer los errores y establecer medidas para evitarlos. Los CCU son lugares sensibles para la aparición, detección y notificación de Incidentes.

Immunogenicity of hypothetical highly conserved proteins as novel antigens in Anaplasma marginale.

Anaplasma marginale is a tick-transmitted Gram-negative intraerythrocytic bacterium and the etiological agent of bovine Anaplasmosis. Even though considerable research efforts have been undertaken, Anaplasmosis vaccine development remains a challenging field. Outer-membrane-specific antigens responsible for the ability of more complex immunogens could have a significant role in the protective response. Thus, the identification of outer-membrane antigens represents a major goal in the development of bacterial vaccines. Considering that 40 % of the annotated proteins in A. marginale remain as hypothetical, we selected three candidate antigens, AM1108, AM127, and AM216 based on experimental evidence, in silico structure prediction of ß-barrel outer membrane, and orthology clustering. Sequence alignment and analysis demonstrated a high degree of conservation for the three proteins between the isolates from Argentina compared to the American strains. We confirmed the transcription of the three genes in the intraerythrocytic stage. AM1108 and AM216 recombinant proteins elicited specific T-cell response proliferation and a significant rise in TNF-α and IFN-γ transcript levels, respectively. Only AM1108 was able to be recognized by specific antibodies from infected bovines. This study allowed the identification of new candidate components of the outer-membrane fraction of A. marginale. Further studies will be required to analyze their potential as effective antigens for being included in rational vaccine strategies.

Inhibition of water absorption in human proximal tubular epithelial cells in response to Shiga toxin-2.

Postdiarrhea hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children in Argentina. It is well established that Shiga toxin type 2 (Stx2) causes direct damage to glomerular endothelial cells and tubular epithelial cells, leading to a reduction in the water handling capacity of the kidney. In this study, we demonstrate that Stx2 and its B subunit (Stx2B) were able to inhibit water absorption across human renal tubular epithelial cell (HRTEC) monolayers without altering the short circuit current and the (3)H-mannitol permeability. Quantitative evaluation of (14)C-inulin transport across HRTEC monolayers showed a similar transport rate both before and after HRTEC treatment with Stx2 that confirmed the integrity of the paracellular pathway. Furthermore, Stx2 produced significant protein synthesis inhibition of HRTEC at concentrations as low as 0.001 ng/ml and 1 h of incubation, whereas Stx2B did not modify it at concentrations as high as 10,000 ng/ml and 6 h of incubation. Our findings suggest that whereas the action of Stx2 appears to be caused mainly by the inhibition of protein synthesis mediated by the A subunit, the binding of Stx2B subunit to the Gb3 receptor may affect the membrane mechanisms related to water absorption. We speculate that inhibition of water absorption may occur in proximal tubular cells in vivo in response to Stx2 and may contribute to the early event of HUS pathogenesis.

Papel de la Toxina Shiga en el sindrome urémico hemolítico / Role of the Shiga toxin in the hemolytic uremic syndrome

In the last years, infection associated with Shiga toxin-producing Escherichia coli (STEC) and subsequent Hemolitic-Uremic Syndrome (HUS) became relevant as a public health since it was considered as one of the most important emergent patogen present in the food contaminated by cattle feces. STEC infection may be asymptomatic or begins with a watery diarrhea that may or may not progress to bloody diarrhea (hemorrhagic colitis) and HUS. In Argentina, HUS is the most common pediatric cause of acute renal insufficiency and the second cause of chronic renal failure. Up to now, STEC infection lacks of known effective treatment strategies that diminish risk of progression to HUS. The mechanisms by which Shiga toxin (Stx) induce HUS may help to find strategies to prevent or ameliorate HUS. In this article, recent progress that has contributed to understanding the disease pathogenesis of STEC is reviewed. New strategies to prevent further uptake of Shiga from the gut, either during the diarrheal phase or once HUS has developed are discussed.

[Cytotoxic effect of Shiga toxin type 2 and its B subunit on human renal tubular epithelial cell cultures]. / Efecto citotóxico de la toxina Shiga tipo 2 y su subunidad B en células epiteliales tubulares renales humanas en cultivo.

Shiga toxin (Stx)-producing E. coli causing watery diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome (HUS). In Argentina, HUS is the most common cause of acute renal failure in children. The purpose of the present study was to examine the cytotoxicity of Stx type 2 (Stx2) and its B subunit (Stx2B) on human renal tubular epithelial cells (HRTEC), in the presence and absence of inflammatory factors. Cytotoxic effects were assessed in terms of functionality of the epithelium, histological damage, cell viability, protein synthesis and cellular apoptosis. Results show that Stx2 regulates the passage of water through the HRTEC within an incubation period of 1h. Within longer periods, up to 72 hours, the study of morphology, viability, protein synthesis and apoptosis shows that HRTEC were sensitive to the cytotoxic action of Stx2 and Stx2B in a dose- and time-dependent manner. These effects were potentiated by lipopolysaccharides (LPS), IL-1beta, and butirate.