is a resident of the human gut. However, certain
toxigenic strains exist that secrete the nonribosomal peptide tilivalline (TV) cytotoxin. TV is a pyrrolobenzodiazepine that causes ...antibiotic-associated hemorrhagic colitis (AAHC). The biosynthesis of TV is driven by enzymes encoded by the
and NRPS operons. In this study, we determined the effect of environmental signals such as carbon sources, osmolarity, and divalent cations on the transcription of both TV biosynthetic operons. Gene expression was enhanced when bacteria were cultivated in tryptone lactose broth. Glucose, high osmolarity, and depletion of calcium and magnesium diminished gene expression, whereas glycerol increased transcription of both TV biosynthetic operons. The cAMP receptor protein (CRP) is a major transcriptional regulator in bacteria that plays a key role in metabolic regulation. To investigate the role of CRP on the cytotoxicity of
, we compared levels of expression of TV biosynthetic operons and synthesis of TV in wild-type strain MIT 09-7231 and a Δ
isogenic mutant. In summary, we found that CRP directly activates the transcription of the
and NRPS operons and that the absence of CRP reduced cytotoxicity of
on HeLa cells, due to a significant reduction in TV production. This study highlights the importance of the CRP protein in the regulation of virulence genes in enteric bacteria and broadens our knowledge on the regulatory mechanisms of the TV cytotoxin.
Introduction
Traumatic brain injury (TBI) is a public health concern with limited treatment options because it causes a cascade of side effects that are the leading cause of hospital death. ...Thioredoxin is an enzyme with neuroprotective properties such as antioxidant, antiapoptotic, immune response modulator, and neurogenic, among others; it has been considered a therapeutic target for treating many disorders.
Methods
The controlled cortical impact (CCI) model was used to assess the effect of recombinant human thioredoxin 1 (rhTrx1) (1 μg/2 μL, intracortical) on rats subjected to TBI at two different times of the light‐dark cycle (01:00 and 13:00 h). We analyzed the food intake, body weight loss, motor coordination, pain perception, and histology in specific hippocampus (CA1, CA2, CA3, and Dental Gyrus) and striatum (caudate‐putamen) areas.
Results
Body weight loss, reduced food intake, spontaneous pain, motor impairment, and neuronal damage in specific hippocampus and striatum regions are more evident in rats subjected to TBI in the light phase than in the dark phase of the cycle and in groups that did not receive rhTrx1 or minocycline (as positive control). Three days after TBI, there is a recovery in body weight, food intake, motor impairment, and pain, which is more pronounced in the rats subjected to TBI at the dark phase of the cycle and those that received rhTrx1 or minocycline.
Conclusions
Knowing the time of day a TBI occurs in connection to the neuroprotective mechanisms of the immune response in diurnal variation and the usage of the Trx1 protein might have a beneficial therapeutic impact in promoting quick recovery after a TBI.
Keratinases present promising biotechnological applications, due to their ability to degrade keratin. Streptomyces appears as one of the main sources of these enzymes, but complete genome sequences ...of keratinolytic bacteria are still limited. This article reports the complete genomes of three marine-derived streptomycetes that show different levels of feather keratin degradation, with high (strain G11C), low (strain CHD11), and no (strain Vc74B-19) keratinolytic activity. A multi-step bioinformatics approach is described to explore genes encoding putative keratinases in these genomes. Despite their differential keratinolytic activity, multiplatform annotation reveals similar quantities of ORFs encoding putative proteases in strains G11C, CHD11, and Vc74B-19. Comparative genomics classified these putative proteases into 140 orthologous groups and 17 unassigned orthogroup peptidases belonging to strain G11C. Similarity network analysis revealed three network communities of putative peptidases related to known keratinases of the peptidase families S01, S08, and M04. When combined with the prediction of cellular localization and phylogenetic reconstruction, seven putative keratinases from the highly keratinolytic strain Streptomyces sp. G11C are identified. To our knowledge, this is the first multi-step bioinformatics analysis that complements comparative genomics with phylogeny and cellular localization prediction, for the prediction of genes encoding putative keratinases in streptomycetes.
Cliff-dwelling plant species are highly specialized and adapted to a vulnerable, fragmented, and are mostly endemic, narrowly-distributed and threatened. As a contribution to the conservation efforts ...of endemic cliff-dwelling species, this study provides an overview of the effects of habitat loss on the abundance and distribution of Pachyphytum caesium (Crassulaceae) due to human disturbances. To achieve this objective, we first conducted a retrospective analysis from 2003–2013 to assess the effects of land use change on the abundance of P. caesium. Secondly, we estimate the abundance and distribution of P. caesium throughout the study area, as well as analyze the effect of rock-climbing activities on the density and population structure of P. caesium. The results suggest differences in population abundance among sites is due to the adverse effects of habitat loss. P. caesium presents a very restricted distribution with small and fragmented populations. In addition, guava agriculture has a significant impact on the chemical soil properties of the hillsides, causing a significant effect on the occurrence of P. caesium, while sport activities remove both the soil and the plants from the cliffs. According to the results, P. caesium is classified as a plant species with extremely small populations (PSESP), and it is highly vulnerable to habitat disturbance. Its conservation is thus a priority to ensure its permanence.
Introducción: Ha ocurrido superpropagación de COVID-19 cuando individuos sintomáticos sin uso de cubrebocas abordaron autobuses. Objetivo: Reportar el riesgo de superpropagación cuando individuos ...presintomáticos abordaron autobuses junto con pasajeros no vacunados, pero se mantuvieron intervenciones preventivas no farmacológicas. Métodos: Estudio prospectivo de personal de salud transportado durante dos semanas en autobuses a un centro de vacunación contra COVID-19. Fue obligatorio llevar ventanas abiertas, uso correcto de cubrebocas y exclusión de personas con síntomas. La vigilancia prospectiva identificó a trabajadores con COVID-19 los 14 días siguientes a la vacunación. Cada pasajero asintomático de autobuses donde se detectaron casos fue vigilado durante un periodo similar. Los resultados de tamizaje voluntario estuvieron disponibles para los trabajadores que se realizaron prueba el mes previo o el siguiente a la vacunación. Resultados: 1879 trabajadores abordaron 65 autobuses. El tiempo a bordo varió de tres a ocho horas. Veintinueve casos de COVID-19 y cuatro casos asintomáticos fueron identificados entre 613 pasajeros de 21 autobuses. La mediana de tiempo entre la vacunación y el inicio de síntomas de COVID-19 fue de seis días. Fue identificado un caso de transmisión sospechada en autobús. Conclusiones: Las intervenciones preventivas no farmacológicas estrictas redujeron sustancialmente el riesgo de superpropagación de COVID-19 en autobuses ocupados por individuos presintomáticos.
Genetic studies in rare species are important to determine their patterns of genetic diversity among populations and implement conservation plans aimed to reduce extinction risks.
is an endemic ...species with extremely small populations in central Mexico. This work analyzes the diversity and genetic structure of
(Crassulaceae) to change the conservation status and propose conservation strategies. Twelve dominant ISSR markers were used to describe the genetic diversity of all known populations. Additionally, we carried out two simulations to explore how the loss of individuals or the local populations extinction affect the genetics parameters of the species. The average results indicated moderate levels of genetic diversity (number of alleles = 89.7 ± 3.9, expected heterozygosity = 0.212 ± 0.0, and percentage of polymorphic loci = 56.1 ± 3.9), parameters that decreased significantly when simulations were performed in
. Additionally, a genetic structure of the populations was found with low gene flow (Nm = 0.92). Genetic parameters are negatively affected by the loss of individuals and the local extinction of populations. Based on our results, we propose to reclassify the conservation status of the species in danger of extinction, hence a series of conservation strategies are provided to prevent its disappearance.
In patients with non–small cell lung cancer, lymph node assessment is essential for appropriate staging. The intrapulmonary lymph nodes (IPLNs) should be considered when assigning the N stage but are ...infrequently evaluated in Colombian centers, resulting in understaging that may hinder optimal treatment.
We conducted a prospective study of IPLN dissection in patients with clinical stage I or II non–small cell lung cancer who underwent surgical resection at 9 institutions in Colombia between 2021 and 2023. IPLN dissection was performed by trained surgeons who collected lymph nodes from fresh specimens after resection and before formalin fixation.
One hundred patients were eligible for the analysis. Their mean age was 67 ± 10.9 years, and 76% were women. Most (74%) had adenocarcinoma, 20% had neuroendocrine tumors, and 6% had squamous cell carcinoma. Successful sampling and histopathologic analysis of at least one IPLN station was obtained in 85% of patients, 9% had upstaging due to positive N2 lymph nodes, and 5% had upstaging due to positive N1 lymph nodes. Among the patients with pN0 or pN1 disease, 3.2% (3 out of 91) were upstaged exclusively due to positive IPLNs.
Fresh-specimen dissection to collect IPLNs is appropriate and feasible to achieve more accurate pathological staging in Colombian lung cancer patients. In clinical N0 patients, IPLN dissection maximizes selection for adjuvant therapy.
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A partir de mayo de 2020, la crisis sanitaria global causada por el virus SARS-CoV-2 traslada su epicentro hacia Latinoamérica, con foco en ciudades que presentan altos índices de pobreza, ...segregación y hacinamiento. Los avances en microbiología posibilitan comprender en profundidad las relaciones entre ciudad, COVID-19 y otros microorganismos, pero falta establecer un marco conceptual que las articule, especialmente en contextos donde las determinantes sociales son tan relevantes. Este artículo tiene como objetivo el proponer una aproximación integrada de microbiología, vivienda, ambiente y urbanismo, a partir de un modelo de interacciones y un análisis empírico para Santiago de Chile. En base a esto, se pudo analizar cómo el proceso de propagación en la ciudad se ve potenciada por vulnerabilidades de índole socio espacial, sanitaria intradomiciliaria y urbana, más una aproximación desde el concepto de pobreza energética. Al mismo tiempo, se pudo comprobar como las variables asociadas a estas vulnerabilidades permitían explicar la tasa de incidencia de casos confirmados por cada 100 000 habitantes a través de las distintas comunas en el área metropolitana de Santiago de Chile. Dentro de éstas, destacan el nivel de hacinamiento de las viviendas, la cantidad de hogares con jefes/as de hogar en trabajo precario y los viajes hacia el distrito central de negocios de la ciudad. Finalmente, se establece la necesidad de proponer una agenda de investigación para este nuevo equipo multidisciplinario de “Microbioma Urbano” en relación con la necesidad de realización de muestreos microbiológicos que permitan mejorar las condiciones de viviendas, barrios y ciudades, aportando en la superación de las vulnerabilidades identificadas en este estudio.
A partir de maig de 2020, la crisi sanitària global causada pel virus SARS-CoV-2 trasllada el seu epicentre cap a Llatinoamèrica, amb focus en ciutats que presenten alts índexs de pobresa, segregació i amuntegament. Els avenços en microbiologia permeten entendre en profunditat les relacions entre ciutat, COVID-19 i altres microorganismes, però cal establir un marc conceptual que les articuli, especialment en contextos on les determinants socials són tan rellevants. Aquest article té com a objectiu el proposar una aproximació integrada de microbiologia, habitatge, ambient i urbanisme, a partir d'un model d'interaccions i una anàlisi empírica per a Santiago de Xile. En base a això, es va poder analitzar com el procés de propagació a la ciutat es veu potenciada per vulnerabilitats d'índole soci espacial, sanitària intra-domiciliaria i urbana, més una aproximació des del concepte de pobresa energètica. Al mateix temps, es va poder comprovar com les variables associades a aquestes vulnerabilitats permetien explicar la taxa d'incidència de casos confirmats per cada 100 000 habitants a través de les diferents comunes a l'àrea metropolitana de Santiago de Xile. Dins d'aquestes, destaquen el nivell d'amuntegament dels habitatges, la quantitat de llars amb caps de la llar en treball precari i els viatges cap al districte central de negocis de la ciutat. Finalment, s'estableix la necessitat de proposar una agenda de recerca per a aquest nou equip multidisciplinari de "Microbioma Urbà" en relació amb la necessitat de realització de mostrejos microbiològiques que permetin millorar les condicions d'habitatges, barris i ciutats, aportant en la superació de les vulnerabilitats identificades en aquest estudi.
As of May 2020, the global health crisis caused by the SARS-CoV-2 virus moves its epicentre to Latin America, with cities showing high rates of poverty, segregation, and overcrowding. Current advances in microbiology make it possible to understand in depth the relationships between cities, COVID-19, and other microorganisms, but a conceptual framework to articulate them is lacking, especially in contexts where social determinants are so relevant. This article proposes an integrated approach to microbiology, housing, environment, and urbanism, based on a model of interactions and an empirical analysis applied to Santiago de Chile. It was possible to analyse how the propagation of COVID-19 in the city is enhanced by vulnerabilities of socio-spatial, residential and urban health, including an approach from the concept of energy poverty. At the same time, it was possible to verify how the variables associated with these vulnerabilities allowed to explain the incidence rate per 100 000 inhabitants through the different communes of Santiago de Chile. Among these, the level of housing overcrowding, the number of households with heads of household in precarious employment, and travel to the central business district stand out. Finally, the need for microbiological sampling to improve housing conditions, neighbourhoods, and cities propose a new research agenda for this Urban Microbiome" multidisciplinary team, contributing to overcoming the vulnerabilities identified in this research.
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