Universidad Católica de Salta

Gut microbiota profoundly influence host physiology, yet most studies rely on bulk-scale intestinal samples, overlooking microbial heterogeneity at the micro-scale. Here, we present a dataset generated from 378 colonic micro-scale grains (20-40 µm) and 20 bulk samples collected from four Kunming mice. Using Illumina NovaSeq 6000 sequencing of the 16S rRNA V4 region, we obtained over 8.0 million raw reads, processed into 1506 amplicon sequence variants (ASVs) spanning 19 phyla and 203 genera. Firmicutes and Bacteroidetes were the dominant phyla across scales, while marked differences were observed in ASV richness (p < 0.001, Wilcoxon test) and network complexity (number of edges, p = 0.03, Wilcoxon test) between bulk samples and micro-scale grains. The dataset, deposited in the NCBI Sequence Read Archive (SRA) under BioProject PRJNA1249752, provides a high-resolution view of gut microbial spatial organization at the sub-100 µm scale. These data advance current understanding of microbial assembly processes, interspecies interactions, and scale-dependent community structure, thereby serving as a valuable resource for microbiome ecology and future mechanistic studies.

Abstract Background Carbapenem-resistant Klebsiella pneumoniae CRKP) represents a critical public health threat, with limited treatment options due to its resistance to last-line antibiotics. Cefiderocol (FDC), a novel siderophore cephalosporin, has shown efficacy against CRKP; however, resistance has emerged. This study characterizes a spontaneous FDC-resistant subpopulation (IHC216) derived from a KPC producing K. pneumoniae strain (KPNMA216). To understand this phenotype, we focused on genomic, transcriptional, and phenotypic adaptations.Figure 1.(A) Expression of genes coding for siderophores (irp1, iucA and entB) and siderophores transporters (fepA, cirA, iroN, fiU and fecA) and β-lactamase blaKPC163 in the KPNMA216 and IHC216 strains. The data shown of qRT-PCR are mean ± SD. Fold changes were calculated using ΔΔCt analysis. At least three independent biological samples were tested using four technical replicates. Statistical significance (P &amp;lt; 0.05) was determined by two-way ANOVA followed by Tukey's multiple comparison test using GraphPad Prism (GraphPad software, San Diego, CA, USA). Significance was indicated by: *P &amp;lt; 0.05, **P &amp;lt; 0.01, ***P &amp;lt; 0.001, and **** P &amp;lt; 0.0001. (B) Biofilm formation in tubes quantified by crystal violet and capsule density in KPC216 and IHC216 strains. three independent biological samples were tested using four technical replicates. A representative image is shown. Statistical analysis was determined by t test (p &amp;lt; 0.05), using GraphPad Prism (GraphPad software, San Diego, CA, USA). Methods Whole-genome sequencing (WGS) was performed to identify genetic mutations associated with FDC resistance. Quantitative real-time PCR (qRT-PCR) was used to assess gene expression changes related to iron acquisition, antibiotic resistance, oxidative stress response, and cell wall synthesis. Antimicrobial susceptibility testing was conducted using minimum inhibitory concentration (MIC) assays. Capsule and biofilm formation were evaluated using standard biochemical assays. Results IHC216 exhibited an increase in FDC MIC compared to the wild-type strain (from 8 to 32 ug/ml). While FDC resistance developed, meropenem MIC decreased from 32 mg/L to 0.5 mg/L, and imipenem MIC from 48 mg/L to 3 mg/L, demonstrating collateral susceptibility. WGS identified mutations in genes linked to transcriptional regulation and membrane permeability. qRT-PCR analysis revealed significant downregulation of key iron acquisition genes and upregulation of alternative iron uptake pathways (Fig.1a). blaKPC-163 expression was markedly reduced, correlating with restored susceptibility to carbapenems (Fig. 1a). Additionally, increased capsule production and biofilm formation were observed (Fig.1b). Conclusion This study highlights the intricate genetic and transcriptional adaptations underlying FDC resistance in KPC-producing K. pneumoniae. The observed collateral susceptibility to carbapenems offers potential treatment strategies that exploit this vulnerability. Understanding these resistance mechanisms is critical for optimizing therapeutic approaches against CRKP infections. Disclosures Robert A. Bonomo, MD, Merck: Grant/Research Support|Shinogi: Grant/Research Support|VenatoRx: Grant/Research Support

This article deals with the principle of good faith in contracts, aiming to determine its actual scope in arm’s length agreements. It posits that the principle’s broad expression may lead to judicial overreach, potentially supplanting the parties will, and above all, exposing them to unnecessary litigation. To test these assumptions, this principle is analyzed from its origins in Roman law, its divergent evolution in common law and civil law systems and its regulation in the new Argentine Civil and Commercial Code. Subsequently, a distintion is made between subjective and objective good faith, the latter being, in general, that which is applicable to contracts. The article discusses the functions of good faith or, in other words, the purposes that good faith serves in contracts. It then sets forth the criticisms made the principle of good faith in contracts, pertaining to its lack of certainty, on the one hand, and the excessive power it grants to judges, on the other. Finally, the study develops a rationale regarding what the scope of this principle should be in arm’s length agreements, and it answers the question, less obvious than it seems at first glance, of whether the parties can agree not to have their contract reviewed under criteria linked to good faith.

Anthelmintic intoxication in cattle is an underreported phenomenon with fragmented data. This study conducted a systematic literature review, following PRISMA guidelines, to identify the chemical groups most frequently associated with intoxication in cattle and the related risk factors. A total of 3,358 articles from four databases were screened, with 17 studies ultimately included, reporting 34 episodes of intoxication. Macrocyclic lactones—particularly abamectin—were most frequently involved, especially in young calves, likely due to their low expression of P-glycoprotein. The clinical signs were predominantly neurological, with no specific pathological lesions. Cases involving levamisole, benzimidazoles, and salicylanilides were also identified, each with distinct toxicological characteristics. This review highlights the need for more careful and technically sound use of anthelmintics, considering factors such as age, physiological status, and management conditions.

En los materiales compuestos, como los cementicios con refuerzo de fibras cortas, el proceso de construcción imparte características que son inherentes a la manufactura y los componentes usados. En los últimos años se desarrollaron investigaciones referidas al uso del cáñamo como refuerzo de los materiales cementicios. Las fibras de cáñamo tienen diámetros pequeños, que rondan los 50 micrones. En este trabajo se plantea una metodología para realizar el relevamiento de fibras de cáñamo dispersas dentro de una matriz cementicia mediante la técnica de microscopía óptica. El relevamiento permite observa la cantidad, sección transversal y ubicación de fibras coloreadas dentro de una sección transversal de probeta aserrada de una viga de pequeñas dimensiones. Por lo anterior, las fibras de cáñamo son teñidas previamente antes de ser incorporadas a la matriz para conseguir un contraste con el medio circundante. Posteriormente los datos extraídos se procesan estadísticamente para obtener estimaciones de cantidad, dispersión y especialmente la longitud de correlación. Estos parámetros son útiles para estimar a posteriori la generación de un campo estocástico que represente una probable disposición del material reforzado con estas fibras. Se informan los resultados obtenidos en vigas de mortero cementicio de dimensiones 40×40×160 mm reforzadas con cáñamo peinado.