Cell-cell metabolite exchange creates a pro-survival metabolic environment that extends lifespan.

Metabolism is deeply intertwined with aging. Effects of metabolic interventions on aging have been explained with intracellular metabolism, growth control, and signaling. Studying chronological aging in yeast, we reveal a so far overlooked metabolic property that influences aging via the exchange of metabolites. We observed that metabolites exported by young cells are re-imported by chronologically aging cells, resulting in cross-generational metabolic interactions. Then, we used self-establishing metabolically cooperating communities (SeMeCo) as a tool to increase metabolite exchange and observed significant lifespan extensions. The longevity of the SeMeCo was attributable to metabolic reconfigurations in methionine consumer cells. These obtained a more glycolytic metabolism and increased the export of protective metabolites that in turn extended the lifespan of cells that supplied them with methionine. Our results establish metabolite exchange interactions as a determinant of cellular aging and show that metabolically cooperating cells can shape the metabolic environment to extend their lifespan.

The proteomic landscape of genome-wide genetic perturbations.

Functional genomic strategies have become fundamental for annotating gene function and regulatory networks. Here, we combined functional genomics with proteomics by quantifying protein abundances in a genome-scale knockout library in Saccharomyces cerevisiae, using data-independent acquisition mass spectrometry. We find that global protein expression is driven by a complex interplay of (1) general biological properties, including translation rate, protein turnover, the formation of protein complexes, growth rate, and genome architecture, followed by (2) functional properties, such as the connectivity of a protein in genetic, metabolic, and physical interaction networks. Moreover, we show that functional proteomics complements current gene annotation strategies through the assessment of proteome profile similarity, protein covariation, and reverse proteome profiling. Thus, our study reveals principles that govern protein expression and provides a genome-spanning resource for functional annotation.

Host-Microbe Co-metabolism Dictates Cancer Drug Efficacy in C. elegans.

Fluoropyrimidines are the first-line treatment for colorectal cancer, but their efficacy is highly variable between patients. We queried whether gut microbes, a known source of inter-individual variability, impacted drug efficacy. Combining two tractable genetic models, the bacterium E. coli and the nematode C. elegans, we performed three-way high-throughput screens that unraveled the complexity underlying host-microbe-drug interactions. We report that microbes can bolster or suppress the effects of fluoropyrimidines through metabolic drug interconversion involving bacterial vitamin B6, B9, and ribonucleotide metabolism. Also, disturbances in bacterial deoxynucleotide pools amplify 5-FU-induced autophagy and cell death in host cells, an effect regulated by the nucleoside diphosphate kinase ndk-1. Our data suggest a two-way bacterial mediation of fluoropyrimidine effects on host metabolism, which contributes to drug efficacy. These findings highlight the potential therapeutic power of manipulating intestinal microbiota to ensure host metabolic health and treat disease.

Spontaneously established syntrophic yeast communities improve bioproduction.

Nutritional codependence (syntrophy) has underexplored potential to improve biotechnological processes by using cooperating cell types. So far, design of yeast syntrophic communities has required extensive genetic manipulation, as the co-inoculation of most eukaryotic microbial auxotrophs does not result in cooperative growth. Here we employ high-throughput phenotypic screening to systematically test pairwise combinations of auxotrophic Saccharomyces cerevisiae deletion mutants. Although most coculture pairs do not enter syntrophic growth, we identify 49 pairs that spontaneously form syntrophic, synergistic communities. We characterized the stability and growth dynamics of nine cocultures and demonstrated that a pair of tryptophan auxotrophs grow by exchanging a pathway intermediate rather than end products. We then introduced a malonic semialdehyde biosynthesis pathway split between different pairs of auxotrophs, which resulted in increased production. Our results report the spontaneous formation of stable syntrophy in S. cerevisiae auxotrophs and illustrate the biotechnological potential of dividing labor in a cooperating intraspecies community.

Lysine harvesting is an antioxidant strategy and triggers underground polyamine metabolism.

Both single and multicellular organisms depend on anti-stress mechanisms that enable them to deal with sudden changes in the environment, including exposure to heat and oxidants. Central to the stress response are dynamic changes in metabolism, such as the transition from the glycolysis to the pentose phosphate pathway-a conserved first-line response to oxidative insults1,2. Here we report a second metabolic adaptation that protects microbial cells in stress situations. The role of the yeast polyamine transporter Tpo1p3-5 in maintaining oxidant resistance is unknown6. However, a proteomic time-course experiment suggests a link to lysine metabolism. We reveal a connection between polyamine and lysine metabolism during stress situations, in the form of a promiscuous enzymatic reaction in which the first enzyme of the polyamine pathway, Spe1p, decarboxylates lysine and forms an alternative polyamine, cadaverine. The reaction proceeds in the presence of extracellular lysine, which is taken up by cells to reach concentrations up to one hundred times higher than those required for growth. Such extensive harvest is not observed for the other amino acids, is dependent on the polyamine pathway and triggers a reprogramming of redox metabolism. As a result, NADPH-which would otherwise be required for lysine biosynthesis-is channelled into glutathione metabolism, leading to a large increase in glutathione concentrations, lower levels of reactive oxygen species and increased oxidant tolerance. Our results show that nutrient uptake occurs not only to enable cell growth, but when the nutrient availability is favourable it also enables cells to reconfigure their metabolism to preventatively mount stress protection.

Genomes shed light on the evolution of Begonia, a mega-diverse genus.

Clarifying the evolutionary processes underlying species diversification and adaptation is a key focus of evolutionary biology. Begonia (Begoniaceae) is one of the most species-rich angiosperm genera with c. 2000 species, most of which are shade-adapted. Here, we present chromosome-scale genome assemblies for four species of Begonia (B. loranthoides, B. masoniana, B. darthvaderiana and B. peltatifolia), and whole genome shotgun data for an additional 74 Begonia representatives to investigate lineage evolution and shade adaptation of the genus. The four genome assemblies range in size from 331.75 Mb (B. peltatifolia) to 799.83 Mb (B. masoniana), and harbor 22 059-23 444 protein-coding genes. Synteny analysis revealed a lineage-specific whole-genome duplication (WGD) that occurred just before the diversification of Begonia. Functional enrichment of gene families retained after WGD highlights the significance of modified carbohydrate metabolism and photosynthesis possibly linked to shade adaptation in the genus, which is further supported by expansions of gene families involved in light perception and harvesting. Phylogenomic reconstructions and genomics studies indicate that genomic introgression has also played a role in the evolution of Begonia. Overall, this study provides valuable genomic resources for Begonia and suggests potential drivers underlying the diversity and adaptive evolution of this mega-diverse clade.

Prevalence and Associated Dietary Factors of Rome IV Functional Gastrointestinal Disorders in Rural Western Honduras.

BACKGROUND: The literature is limited regarding the prevalence of functional gastrointestinal disorders (FGIDs) in Central America, and the role of dietary factors. METHODS: The Rome IV diagnostic questionnaire and National Cancer Institute Diet History questionnaire were administered in one-on-one interviews to a distributed cross section of the general adult population of Western Honduras. Our aim was to estimate prevalence of common FGIDs and symptoms and their relationships to dietary habits. RESULTS: In total, 815 subjects were interviewed, of whom 151 fulfilled criteria for an FGID (18.5%). Gastroduodenal FGIDs were noted in 9.4%, with epigastric pain syndrome (EPS) more common than postprandial distress syndrome, 8.5% versus 1.6%. Among bowel disorders, functional abdominal bloating (FAB) was most prevalent (6.3%), followed by irritable bowel syndrome (3.6%), functional diarrhea (FDr; 3.4%), and functional constipation (1.1%). A significant inverse association was noted between regular bean intake and any FGID (OR 0.41, 95% CI 0.27-0.63), driven by IBS and FDr. Vegetable consumption was associated with lower prevalence of functional diarrhea (OR 0.12; 95% CI 0.04-0.35) and any diarrheal disorder (OR 0.11; 95% CI 0.04-0.31). Subjects with a median daily intake of ≥ 4 corn tortillas had 1.75 (95% CI 1.22-2.50) times the odds of having any FGID. CONCLUSIONS: FGIDs were common in this rural low-resource setting in Central America, with an intriguing distribution of specific FGIDs. EPS and FAB were common, but IBS was not. Local dietary factors were associated with specific FGIDs, suggesting that diet may play a role in global variations of FGIDs.

Natural variation of photosynthetic efficiency in Arabidopsis thaliana accessions under low temperature conditions.

Low, but non-freezing, temperatures have negative effects on plant growth and development. Despite some molecular signalling pathways being known, the mechanisms causing different responses among genotypes are still poorly understood. Photosynthesis is one of the processes that are affected by low temperatures. Using an automated phenotyping platform for chlorophyll fluorescence imaging the steady state quantum yield of photosystem II (PSII) electron transport (ΦPSII ) was measured and used to quantify the effect of moderately low temperature on a population of Arabidopsis thaliana natural accessions. Observations were made over the course of several weeks in standard and low temperature conditions and a strong decrease in ΦPSII upon the cold treatment was found. A genome wide association study identified several quantitative trait loci (QTLs) that are associated with changes in ΦPSII in low temperature. One candidate for a cold specific QTL was validated with a mutant analysis to be one of the genes that is likely involved in the PSII response to the cold treatment. The gene encodes the PSII associated protein PSB27 which has already been implicated in the adaptation to fluctuating light.

The spatiotemporal evolution of compound impacts from lava flow and tephra fallout on buildings: lessons from the 2021 Tajogaite eruption (La Palma, Spain).

The simultaneous or sequential occurrence of several hazards-be they of natural or anthropogenic sources-can interact to produce unexpected compound hazards and impacts. Since success in responding to volcanic crises is often conditional on accurate identification of spatiotemporal patterns of hazard prior to an eruption, ignoring these interactions can lead to a misrepresentation or misinterpretation of the risk and, during emergencies, ineffective management priorities. The 2021 eruption of Tajogaite volcano on the island of La Palma, Canary Islands (Spain), was an 86 day-long hybrid explosive-effusive eruption that demonstrated the challenges of managing volcanic crises associated with the simultaneous emission of lava, tephra and volcanic gases. Here, we present the result of a small-scale impact assessment conducted during three-field deployments to investigate how tephra fallout and lava flow inundation interacted to cause compound physical impact on buildings. The study area was a neighbourhood of 30 buildings exposed to tephra fallout during the entire eruption and by a late-stage, short-lived lava flow. Observations highlight, on one hand, the influence of clean-up operations and rainfall on the impact of tephra fallout and, on the other hand, the importance of the dynamics of lava flow emplacement in controlling impact mechanisms. Overall, results provide an evidence-based insight into impact sequences when two primary hazards are produced simultaneously and demonstrate the importance of considering this aspect when implementing risk mitigation strategies for future long-lasting, hybrid explosive-effusive eruptions in urban environments. Supplementary Information: The online version contains supplementary material available at 10.1007/s00445-023-01700-w.

Population-based Study of Gastric Cancer Survival and Associations in Rural Western Honduras.

BACKGROUND: Two-thirds of global cancer occur in low/middle income countries (LMICs). Northern Central America is the largest LMIC region in the western hemisphere, and lack cancer registries to guide cancer control. We conducted a gastric cancer (GC) survival study in rural western Honduras, characterized as having among the highest GC incidence rates in Latin America. METHODS: The cohort of incident GC diagnosed between 2002-2015 was studied with active follow-up, with household visits. The regional gastric cancer registry was primary for case identification, with completeness examination with hospital data and national death certificates. Cox regression models were used for survival calculations. RESULTS: Survival follow-up was achieved in 741/774 patients (95.7%). Household interviews were conducted in 74.1% (n=549). 65.7% were male, median age at diagnosis was 64 years, 24.5% were <55. 43.9% of tumors had pyloric obstruction. 45.2%, 43.2%, and 7.3% of histology was intestinal, diffuse, and mixed, respectively. 24.7% patients received treatment. 5-year survival rates were 9.9% for both males and females, 7.7% for age <45, and 7.9% for diffuse GC. Median survival time was 4.8 months (95%CI,4.2-5.6). In the final Cox regression model including age, sex, Lauren subtype, and poverty index, only treatment was significantly associated with survival (HR 2.43, 95%CI,1.8-3.2). CONCLUSIONS: Markedly low gastric cancer 5-year survival rates are observed in rural Central America. The majority of patients present with advanced disease, and a minority have access to therapy. IMPACT: The findings have implications for cancer control in the Central America LMICs and for U.S. Latino populations.

A DNA barcoding framework for taxonomic verification in the Darwin Tree of Life Project.

Biodiversity genomics research requires reliable organismal identification, which can be difficult based on morphology alone. DNA-based identification using DNA barcoding can provide confirmation of species identity and resolve taxonomic issues but is rarely used in studies generating reference genomes. Here, we describe the development and implementation of DNA barcoding for the Darwin Tree of Life Project (DToL), which aims to sequence and assemble high quality reference genomes for all eukaryotic species in Britain and Ireland. We present a standardised framework for DNA barcode sequencing and data interpretation that is then adapted for diverse organismal groups. DNA barcoding data from over 12,000 DToL specimens has identified up to 20% of samples requiring additional verification, with 2% of seed plants and 3.5% of animal specimens subsequently having their names changed. We also make recommendations for future developments using new sequencing approaches and streamlined bioinformatic approaches.

Identifying species based solely on their morphology can be difficult. DNA-based identification using DNA barcoding can aid species identification, but can be challenging to implement in biodiversity projects sampling diverse organismal groups. Here, we describe the development and implementation of DNA barcoding for the Darwin Tree of Life Project (DToL), which aims to sequence and assemble high quality reference genomes for all eukaryotic species in Britain and Ireland. We discuss how a standardised approach has been adapted by each partner to suit different organismal groups, show the efficacy of this approach for confirming species identities and resolving taxonomic issues, and make recommendations for future developments.

Nutrigenomics of inward rectifier potassium channels.

Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg2+. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.

[Nutritional, bone and body composition assessment of patients with knee and hip arthroplasty]. / Valoración nutricional, ósea y de composición corporal de pacientes con artroplastia de rodilla y cadera.

Introduction: Introduction: malnutrition, both due to deficiency and excess of nutrients, correlates to the morbidity of the surgical patient. Objectives: to analyze the nutritional status, body composition and bone health of patients undergoing elective knee and hip arthroplasty. Methods: an observational cross-sectional study was carried out evaluating patients undergoing hip and knee replacement surgery from February to September 2019. The Malnutrition Universal Screening Tool (MUST), anthropometry, hand-grip dynamometry, bone densitometry, lumbar spine X-ray and bioimpedance analysis were performed. Results: eighty-six patients (61.6 % women) were evaluated, with a mean age of 69.5 ± 9.5 years. The mean body mass index (BMI) was 31.3 ± 4.5. According to MUST, 21.3 % were at risk of malnutrition; 16.9 % had decreased triceps skinfold with respect to p50 and 20 % had a pathological hand-grip dynamometry. In 91.4 %, vitamin D was < 30 pg/ml. In the bioimpedanciometry, the women presented significantly decreased muscle mass values. Age was correlated with a lower presence of fat-free mass, total and appendicular muscle mass. In those over 65 years of age, 52.6 % of men vs 14.3 % of women had a decreased muscle mass index; 58.5 % had low bone mineral density. We observed vertebral bone collapses in 13.9 %. Conclusion: there is a high prevalence of obesity in patients who are candidates for arthroplasty and this does not exclude the existence of a risk of malnutrition. They may also have decreased muscle mass and strength. Nutritional education and physical exercise recommendations are essential in order to optimize nutritional status for surgery.

Introducción: Introducción: la malnutrición tanto por defecto como por exceso de nutrientes se relaciona con la morbilidad del paciente quirúrgico. Objetivos: analizar el estado nutricional, la composición corporal y la salud ósea de pacientes sometidos a artroplastia electiva de rodilla y cadera Método: se realiza un estudio transversal observacional evaluando pacientes que ingresan para cirugía de prótesis de cadera y rodilla de febrero a septiembre de 2019. Al ingreso, se realizan Malnutrition Universal Screening Tool (MUST), antropometría, dinamometría manual, densitometría ósea, radiografía de columna lumbar y bioimpedanciometría. Resultados: se evaluó a 86 pacientes (61,6 % mujeres), con edad media de 69,5 ± 9,5 años. El índice de masa corporal (IMC) medio fue de 31,3 ± 4,5. Según MUST, el 21,3 % estaba en riesgo de desnutrición. El 16,9 % tenía disminuido el pliegue tricipital respecto al p50 y el 20 % tenía una dinamometría manual patológica. En el 91,4 % la vitamina D fue < 30 pg/ml. En la bioimpedanciometría, las mujeres presentaban valores de masa muscular significativamente disminuidos. La edad se correlacionó con menor presencia de masa libre de grasa, masa muscular total y apendicular. En mayores de 65 años, el 52,6 % de varones vs. 14,3 % de mujeres presentaban un índice de masa muscular disminuido. El 58,5 % tenía densidad mineral ósea baja. Objetivamos aplastamientos vertebrales en el 13,9 %. Conclusiones: existe una alta prevalencia de obesidad en pacientes candidatos a artroplastia y esto no excluye la existencia de riesgo de desnutrición. Además, pueden presentar disminución de masa y fuerza muscular. Es fundamental la educación nutricional y recomendaciones de ejercicio físico de cara a optimizar el estado nutricional para cirugía.

Microbial communities form rich extracellular metabolomes that foster metabolic interactions and promote drug tolerance.

Microbial communities are composed of cells of varying metabolic capacity, and regularly include auxotrophs that lack essential metabolic pathways. Through analysis of auxotrophs for amino acid biosynthesis pathways in microbiome data derived from >12,000 natural microbial communities obtained as part of the Earth Microbiome Project (EMP), and study of auxotrophic-prototrophic interactions in self-establishing metabolically cooperating yeast communities (SeMeCos), we reveal a metabolically imprinted mechanism that links the presence of auxotrophs to an increase in metabolic interactions and gains in antimicrobial drug tolerance. As a consequence of the metabolic adaptations necessary to uptake specific metabolites, auxotrophs obtain altered metabolic flux distributions, export more metabolites and, in this way, enrich community environments in metabolites. Moreover, increased efflux activities reduce intracellular drug concentrations, allowing cells to grow in the presence of drug levels above minimal inhibitory concentrations. For example, we show that the antifungal action of azoles is greatly diminished in yeast cells that uptake metabolites from a metabolically enriched environment. Our results hence provide a mechanism that explains why cells are more robust to drug exposure when they interact metabolically.

Multi-tissue transcriptome analysis of two Begonia species reveals dynamic patterns of evolution in the chalcone synthase gene family.

Begonia is an important horticultural plant group, as well as one of the most speciose Angiosperm genera, with over 2000 described species. Genus wide studies of genome size have shown that Begonia has a highly variable genome size, and analysis of paralog pairs has previously suggested that Begonia underwent a whole genome duplication. We address the contribution of gene duplication to the generation of diversity in Begonia using a multi-tissue RNA-seq approach. We chose to focus on chalcone synthase (CHS), a gene family having been shown to be involved in biotic and abiotic stress responses in other plant species, in particular its importance in maximising the use of variable light levels in tropical plants. We used RNA-seq to sample six tissues across two closely related but ecologically and morphologically divergent species, Begonia conchifolia and B. plebeja, yielding 17,012 and 19,969 annotated unigenes respectively. We identified the chalcone synthase gene family members in our Begonia study species, as well as in Hillebrandia sandwicensis, the monotypic sister genus to Begonia, Cucumis sativus, Arabidopsis thaliana, and Zea mays. Phylogenetic analysis suggested the CHS gene family has high duplicate turnover, all members of CHS identified in Begonia arising recently, after the divergence of Begonia and Cucumis. Expression profiles were similar within orthologous pairs, but we saw high inter-ortholog expression variation. Sequence analysis showed relaxed selective constraints on some ortholog pairs, with substitutions at conserved sites. Evidence of pseudogenisation and species specific duplication indicate that lineage specific differences are already beginning to accumulate since the divergence of our study species. We conclude that there is evidence for a role of gene duplication in generating diversity through sequence and expression divergence in Begonia.

Western Honduras Copán Population-Based Cancer Registry: Initial Estimates and a Model for Rural Central America.

PURPOSE: Population-based cancer registries (PBCRs) are critical for national cancer control planning, yet few low- and middle-income countries (LMICs) have quality PBCRs. The Central America Four region represents the principal LMIC region in the Western hemisphere. We describe the establishment of a PBCR in rural Western Honduras with first estimates for the 2013-2017 period. METHODS: The Western Honduras PBCR was established through a collaboration of academic institutions and the Honduras Ministry of Health for collection of incident cancer data from public and private health services. Data were recorded using the Research Electronic Data Capture (REDCap) web-based platform with data monitoring and quality checks. Crude and age-standardized rates (ASRs) were calculated at the regional level, following WHO methodology. RESULTS: The web-based platform for data collection, available ancillary data services (eg, endoscopy), and technical support from international centers (United States and Colombia) were instrumental for quality control. Crude cancer incidence rates were 112.2, 69.8, and 154.6 per 100,000 habitants overall, males, and females, respectively (excluding nonmelanoma skin cancer). The adjusted ASRs were 84.2, 49.6, and 118.9 per 100,000 overall habitants, males, and females, respectively. The most common sites among men were stomach (ASR 26.0, 52.4%), colorectal (ASR 5.11, 10.15%), and prostate (ASR 2.7, 5.4%). The most common sites in women were cervix (ASR 34.2, 36.7%), breast (ASR 11.2, 12.3%), and stomach (ASR 10.8, 11.7%). CONCLUSION: The Copán-PBCR represents a successful model to develop cancer monitoring in rural LMICs. Innovations included the use of the REDCap platform and leverage of Health Ministry resources. This provides the first PBCR data for Honduras and the Central America Four and confirms that infection-driven cancers, such as gastric and cervical, should be priority targets for cancer control initiatives.

Gene-Trait Matching and Prevalence of Nisin Tolerance Systems in Lactococus lactis.

Lactococcus lactis cheese starter cultures typically contain a mix of many strains and may include variants that produce and/or tolerate the antimicrobial bacteriocin nisin. Nisin is well-established as an effective agent against several undesirable Gram-positive bacteria in cheese and various other foods. In the current study, we have examined the effect of nisin on 710 individual L. lactis strains during milk fermentations. Changes in milk acidification profiles with and without nisin exposure, ranging from unaltered acidification to loss of acidification, could be largely explained by the type(s) and variants of nisin immunity and nisin degradation genes present, but surprisingly, also by genotypic lineage (L. lactis ssp. cremoris vs. ssp. lactis). Importantly, we identify that nisin degradation by NSR is frequent among L. lactis and therefore likely the main mechanism by which dairy-associated L. lactis strains tolerate nisin. Insights from this study on the strain-specific effect of nisin tolerance and degradation during milk acidification is expected to aid in the design of nisin-compatible cheese starter cultures.

Bidirectional Ventricular Tachycardia in a Women with Dilated Cardiomyopathy: A Case Report.

INTRODUCTION: Bidirectional ventricular tachycardia (BVT) is a rare arrhythmia characterized by QRS complexes with an axis in the frontal plane alternating polarity in the precordial leads and right bundle branch block (RBBB) morphology. To the best of our knowledge, there is no previous report in dilated cardiomyopathy or in the context of a probable peripartum cardiomyopathy. CASE PRESENTATION: A 26-year-old, 9-month female patient, with no significant past medical history (the patient denies medication intake, herbs like aconite, trouble during delivery, any heart issues or family history of sudden death or cardiomyopathies) who presents to the emergency room due to 11 days of dyspnea, exacerbated by daily activities, orthopnea, and paroxysmal nocturnal dyspnea. She presented with ventricular bigeminy and systolic dysfunction with left ventricular ejection fraction (LVEF) <20%. The patient later developed a stable ventricular tachycardia (VT) treated with amiodarone, which resulted in hemodynamic instability and BVT rhythm with VT paroxysms. Without the possibility of ablation, the use of high dose beta blockers and an implantable cardioverter defibrillator resulted in the same rhythm with a lower heart rate, better NYHA functional class, and less episodes of VTs. CONCLUSION: BVT is a rare type of tachycardia that can be present in dilated cardiomyopathy. In the absence of ablation capabilities, decreasing the heart rate with beta-blockers may reduce the rate of paroxysmal VTs.

Mass flux decay timescales of volcanic particles due to aeolian processes in the Argentinian Patagonia steppe.

We investigate the timescales of the horizontal mass flux decay of wind remobilised volcanic particles in Argentina, associated with the tephra-fallout deposit produced by the 2011-2012 Cordón Caulle (Chile) eruption. Particle removal processes are controlled by complex interactions of meteorological conditions, surface properties and particle depletion with time. We find that ash remobilisation follows a two-phase exponential decay with specific timescales for the initial input of fresh ash (1-74 days) and the following soil stabilisation processes (3-52 months). The characteristic timescales as a function of particle size shows two minimum values, identified for sizes around 2 and 19-37 [Formula: see text]m, suggesting that these size-range particles are remobilised more easily, due to the interaction between saltation and suspension-induced processes. We find that in volcanic regions, characterised by a sudden release and a subsequent depletion of particles, the availability of wind-erodible particles plays a major role due to compaction and removal of fine particles. We propose, therefore, a simple and reproducible empirical model to describe the mass flux decay of remobilised ash in a supply-limited environment. This methodology represents an innovative approach to link field measurements of multi-sized and supply-limited deposits with saltation erosion theory.