Evaluating Short-Term Outcomes of Tunneled and Non-Tunneled Central Venous Catheters in Hemodialysis.

Background: The necessity of using central venous catheters (CVCs) in hemodialysis, coupled with their associated complications, remains a critical concern in nephrology. This study aims to compare the short-term prognosis of tunneled (T-CVC) and non-tunneled (NT-CVC) CVCs in acute hemodialysis patients, specifically focusing on infection rates, malpositioning, and lumen thrombosis within the first three weeks post-insertion. Methods: A retrospective analysis was conducted on 176 CVCs placed between January and December 2023 at the Policlinico di Modena and the Ospedale Civile di Baggiovara. Patient demographics, CHA2DS2-VASc scores, and comorbid conditions were recorded at the time of catheter placement. Outcomes assessed included catheter-related infections, malpositioning, and lumen thrombosis. Statistical analyses, including Chi-square tests, Fisher's exact tests, and Kaplan-Meier survival analysis, were performed to evaluate differences between T-CVCs and NT-CVCs. Results: The sample comprised 43% females with a mean age of 69.3 years (SD 13.9) and a mean CHADS-VASC score of 3.72 (SD 1.4). Hypertension (90%) was the most prevalent comorbidity. Of the 176 CVCs, 127 were T-CVCs and 49 were NT-CVCs. Infection rates were 3.15% for T-CVCs and 8.16% for NT-CVCs (p = 0.07). Malpositioning occurred in 0.79% of T-CVCs and 4.08% of NT-CVCs (p = 0.47). There was one case of lumen thrombosis in the NT-CVC group. Kaplan-Meier analysis indicated a significant divergence in infection-related catheter survival favoring T-CVCs after ten days (p = 0.034). Conclusions: While non-tunneled CVCs do not significantly alter short-term prognosis compared to tunneled CVCs, the latter show a better infection-related survival rate beyond ten days. Therefore, primary insertion of T-CVCs may be preferable when resources and clinical conditions permit, although NT-CVCs remain a viable option when immediate T-CVC insertion is challenging.

Exploring the Role of Cell-Free Nucleic Acids and Peritoneal Dialysis: A Narrative Review.

INTRODUCTION: Cell-free nucleic acids (cf-NAs) represent a promising biomarker of various pathological and physiological conditions. Since its discovery in 1948, cf-NAs gained prognostic value in oncology, immunology, and other relevant fields. In peritoneal dialysis (PD), blood purification is performed by exposing the peritoneal membrane. Relevant sections: Complications of PD such as acute peritonitis and peritoneal membrane aging are often critical in PD patient management. In this review, we focused on bacterial DNA, cell-free DNA, mitochondrial DNA (mtDNA), microRNA (miRNA), and their potential uses as biomarkers for monitoring PD and its complications. For instance, the isolation of bacterial DNA in early acute peritonitis allows bacterial identification and subsequent therapy implementation. Cell-free DNA in peritoneal dialysis effluent (PDE) represents a marker of stress of the peritoneal membrane in both acute and chronic PD complications. Moreover, miRNA are promising hallmarks of peritoneal membrane remodeling and aging, even before its manifestation. In this scenario, with multiple cytokines involved, mtDNA could be considered equally meaningful to determine tissue inflammation. CONCLUSIONS: This review explores the relevance of cf-NAs in PD, demonstrating its promising role for both diagnosis and treatment. Further studies are necessary to implement the use of cf-NAs in PD clinical practice.

A new mechanism shapes the naïve CD8+ T cell repertoire: the selection for full diversity.

During thymic T cell differentiation, TCR repertoires are shaped by negative, positive and agonist selection. In the thymus and in the periphery, repertoires are also shaped by strong inter-clonal and intra-clonal competition to survive death by neglect. Understanding the impact of these events on the T cell repertoire requires direct evaluation of TCR expression in peripheral naïve T cells. Several studies have evaluated TCR diversity, with contradictory results. Some of these studies had intrinsic technical limitations since they used material obtained from T cell pools, preventing the direct evaluation of clonal sizes. Indeed with these approaches, identical TCRs may correspond to different cells expressing the same receptor, or to several amplicons from the same T cell. We here overcame this limitation by evaluating TCRB expression in individual naïve CD8+ T cells. Of the 2269 Tcrb sequences we obtained from 13 mice, 99% were unique. Mathematical analysis of the data showed that the average number of naïve peripheral CD8+ T cells expressing the same TCRB is 1.1 cell. Since TCRA co-expression studies could only increase repertoire diversity, these results reveal that the number of naïve T cells with unique TCRs approaches the number of naïve cells. Since thymocytes undergo multiple rounds of divisions after TCRB rearrangement and 3-5% of thymocytes survive thymic selection events the number of cells expressing the same TCRB was expected to be much higher. Thus, these results suggest a new repertoire selection mechanism, which strongly selects for full TCRB diversity.

An evaluation of the PacBio RS platform for sequencing and de novo assembly of a chloroplast genome.

BACKGROUND: Second generation sequencing has permitted detailed sequence characterisation at the whole genome level of a growing number of non-model organisms, but the data produced have short read-lengths and biased genome coverage leading to fragmented genome assemblies. The PacBio RS long-read sequencing platform offers the promise of increased read length and unbiased genome coverage and thus the potential to produce genome sequence data of a finished quality containing fewer gaps and longer contigs. However, these advantages come at a much greater cost per nucleotide and with a perceived increase in error-rate. In this investigation, we evaluated the performance of the PacBio RS sequencing platform through the sequencing and de novo assembly of the Potentilla micrantha chloroplast genome. RESULTS: Following error-correction, a total of 28,638 PacBio RS reads were recovered with a mean read length of 1,902 bp totalling 54,492,250 nucleotides and representing an average depth of coverage of 320× the chloroplast genome. The dataset covered the entire 154,959 bp of the chloroplast genome in a single contig (100% coverage) compared to seven contigs (90.59% coverage) recovered from an Illumina data, and revealed no bias in coverage of GC rich regions. Post-assembly the data were largely concordant with the Illumina data generated and allowed 187 ambiguities in the Illumina data to be resolved. The additional read length also permitted small differences in the two inverted repeat regions to be assigned unambiguously. CONCLUSIONS: This is the first report to our knowledge of a chloroplast genome assembled de novo using PacBio sequence data. The PacBio RS data generated here were assembled into a single large contig spanning the P. micrantha chloroplast genome, with a higher degree of accuracy than an Illumina dataset generated at a much greater depth of coverage, due to longer read lengths and lower GC bias in the data. The results we present suggest PacBio data will be of immense utility for the development of genome sequence assemblies containing fewer unresolved gaps and ambiguities and a significantly smaller number of contigs than could be produced using short-read sequence data alone.