Skin-derived fibroblasts from long-lived species are resistant to some, but not all, lethal stresses and to the mitochondrial inhibitor rotenone

Fibroblast cell lines were developed from skin biopsies of eight species of wild-trapped rodents, one species of bat, and a group of genetically heterogeneous laboratory mice. Each cell line was tested in vitro for their resistance to six varieties of lethal stress, as well as for resistance to the nonlethal metabolic effects of the mitochondrial inhibitor rotenone and of culture at very low glucose levels. Standard linear regression of species-specific lifespan against each species mean stress resistance showed that longevity was associated with resistance to death induced by cadmium and hydrogen peroxide, as well as with resistance to rotenone inhibition. A multilevel regression method supported these associations, and suggested a similar association for resistance to heat stress. Regressions for resistance to cadmium, peroxide, heat, and rotenone remained significant after various statistical adjustments for body weight. In contrast, cells from longer-lived species did not show significantly greater resistance to ultraviolet light, paraquat, or the DNA alkylating agent methylmethanesulfonate. There was a strong correlation between species longevity and resistance to the metabolic effects of low-glucose medium among the rodent cell lines, but this test did not distinguish mice and rats from the much longer-lived little brown bat. These results are consistent with the idea that evolution of long-lived species may require development of cellular resistance to several forms of lethal injury, and provide justification for evaluation of similar properties in a much wider range of mammals and bird species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73523/1/j.1474-9726.2006.00255.x.pd

Genetic interactions between a phospholipase A2 and the Rim101 pathway components in S. cerevisiae reveal a role for this pathway in response to changes in membrane composition and shape

Modulating composition and shape of biological membranes is an emerging mode of regulation of cellular processes. We investigated the global effects that such perturbations have on a model eukaryotic cell. Phospholipases A2 (PLA2s), enzymes that cleave one fatty acid molecule from membrane phospholipids, exert their biological activities through affecting both membrane composition and shape. We have conducted a genome-wide analysis of cellular effects of a PLA2 in the yeast Saccharomyces cerevisiae as a model system. We demonstrate functional genetic and biochemical interactions between PLA2 activity and the Rim101 signaling pathway in S. cerevisiae. Our results suggest that the composition and/or the shape of the endosomal membrane affect the Rim101 pathway. We describe a genetically and functionally related network, consisting of components of the Rim101 pathway and the prefoldin, retromer and SWR1 complexes, and predict its functional relation to PLA2 activity in a model eukaryotic cell. This study provides a list of the players involved in the global response to changes in membrane composition and shape in a model eukaryotic cell, and further studies are needed to understand the precise molecular mechanisms connecting them

Accuracy of citrulline, I-FABP and d-lactate in the diagnosis of acute mesenteric ischemia

Data availability: Research data are not shared.Supplementary Information oi available online at: https://www.nature.com/articles/s41598-021-98012-w#Sec14 .Early diagnosis of acute mesenteric ischemia (AMI) remains a clinical challenge, and no biomarker has been consistently validated. We aimed to assess the accuracy of three promising circulating biomarkers for diagnosing AMI—citrulline, intestinal fatty acid-binding protein (I-FABP), and D-lactate. A cross-sectional diagnostic study enrolled AMI patients admitted to the intestinal stroke center and controls with acute abdominal pain of another origin. We included 129 patients—50 AMI and 79 controls. Plasma citrulline concentrations were significantly lower in AMI patients compared to the controls [15.3 μmol/L (12.0–26.0) vs. 23.3 μmol/L (18.3–29.8), p = 0.001]. However, the area under the receiver operating curves (AUROC) for the diagnosis of AMI by Citrulline was low: 0.68 (95% confidence interval = 0.58–0.78). No statistical difference was found in plasma I-FABP and plasma D-lactate concentrations between the AMI and control groups, with an AUROC of 0.44, and 0.40, respectively. In this large cross-sectional study, citrulline, I-FABP, and D-lactate failed to differentiate patients with AMI from patients with acute abdominal pain of another origin. Further research should focus on the discovery of new biomarkers.Grants from MSD-Avenir and APHP funded the SURVIBIO study; Alexandre Nuzzo received Ph.D. Grants from “Fondation de l'Avenir” and the French Gastroenterology Society (SNFGE)

Walk inside Hofstadter's butterfly

This paper describes with help of numerically computed pictures the fascinating properties of the spectrum of Harper's equation in the spirit of celebrated Hofstadter's picture. We hope to explain recent results obtained by mathematicians and physicists about the Cantor structure of this spectrum.Cet article est une invitation à comprendre à l'aide de dessins calculés numériquement les propriétés du spectre de l'équation de Harper dans l'esprit du célèbre dessin dû à Hofstadter. On cherchera ainsi à expliquer certains résultats récents de mathématiciens et de physiciens sur la structure cantorienne de ce spectre

Multidrug resistance gene-1 polymorphisms and resistance to cyclosporine a in patients with steroid resistant ulcerative colitis

Background: Cyclosporine A (CsA) is inconstantly effective in inducing remission in acute attacks of ulcerative colitis (UC) not responding to steroids. This study aimed to establish whether multidrug resistance gene (MDR)1 polymorphisms would be associated with CsA failure. Patients and Methods: The distribution of the different genotypes of single nucleotide polymorphisms (SNP) G2677T/A and C3435T of MDR1 exons 21 and 26, respectively, was studied in 154 patients (mean age, 44 yr) who had received CsA to treat severe attacks of steroid resistant UC in 11 centers in France and Belgium. Patients were classified as CsA failure (n = 50) when they needed colectomy within 30 days after CsA initiation. The SNPs were detected by use of a 5' nuclease allelic discrimination assay. Results: There was a significant association between the G2677T/A polymorphism distribution (exon 21) and the risk for CsA failure (P = 0.0001). The TT genotype of exon 21 was significantly associated with the risk compared with the two other genotypes (odds ratio, 3.77; 95% confidence interval, 1.42-9.97, P = 0.007). There was no significant association between the genotype C3435T distribution (exon 26) and the risk of CsA failure (P = 0.23). Conclusion: The TT genotype of exon 21 MDR1 polymorphisms is associated with a higher risk of CsA failure in patients with steroid resistant UC. Further studies should be performed to establish whether other treatments could be more efficient to avoid surgery in this subset of patients

P579 Real-world comparison of effectiveness between tofacitinib and ustekinumab in patients with ulcerative colitis exposed to at least one anti-TNF agent: results from the TORUS study

International audienceBackground We aimed to compare the effectiveness of tofacitinib and ustekinumab in patients with ulcerative colitis (UC) previously exposed to at least one anti-TNF agent. Methods In this multicenter study, we retrospectively included consecutive UC adult patients previously exposed to at least one anti-TNF agent, with partial Mayo score (pMS) > 2, having who started tofacitinib or ustekinumab between January 2019 and June 2022. The primary endpoint was steroid-free clinical remission (pMS ≤ 2) (CFREM) at week 16 (W16). Secondary endpoints were endoscopic remission (CFREM + Mayo endoscopic score (MES) ≤ 1), and histological remission (CFREM + MES ≤ 1 + Nancy index ≤ 1). Comparisons were performed using propensity score analyses adjusted on potential confounders. Results Overall, 289 patients were included (tofacitinib = 124 patients, ustekinumab = 165 patients). The groups were comparable (tofacitinib vs vedolizumab) for male gender (50.8% vs 43.3%), mean age (40.7 vs 42.9 years), median UC duration (8.6 vs 9.3 years), concomitant use of 5-ASA (13.7% vs 9.7%), steroids (25.0% vs 29.7%), immunosuppressants (7.3% vs 5.5%), and ≥ 2 prior biologics (85.5% vs 82.4%). Tofacitinib group had more pancolitis (55.6% vs 42.4%, p = 0.026) and UC with pMS > 6 (64.5% vs 50.3%, p = 0.016). In our study, 42.1 % of the patients treated with tofacitinib continued using a dose of 10 mgx2/day until W16 while 47.3% of the patients on ustekinumab required dose escalation to 90 mg/4 weeks before W16. After propensity score analysis, the rate of CFREM at W16 was 37.8% and 35.6% in the tofacitinib and ustekinumab arms, respectively arm (p=0.75). CFREM at W16 was achieved in 43.3% vs 57.1% (p = 0.48) after failure of one biologic, 20.7% vs 37.9% (p=0.16) two biologics and 46.7% vs 23.2% (p=0.047) or ≥ 3 biologics, in tofacitinib and vedolizumab arms, respectively. After primary failure to at least one biologic, the rate of CFREM at W16 was 46.3% on tofacitinib vs 25.9% on ustekinumab (p = 0.13). CFREM at W16 was similar with tofacitinib and ustekinumab in case of more severe UC such as pMS ≥ 6 (40.6% vs 41.5%) and CRP > 30 (27.2% vs 33.0%). No predictor of tofacitinib effectiveness has been identified. Factors associated with no CFREM at W16 on ustekinumab were male gender (p=0.035), ≥ 3 prior biologics (p=0.013), prior use of tofacitinib (p=0.03), primary failure to at least one biologic (p=0.013). Endoscopic remission was achieved in 17.0% vs 11.7% (p =0.47) and histological remission in 4.4% vs 7.8% (p=0.32) of the patients treated with tofacitinib and ustekinumab, respectively. Conclusion Tofacitinib and ustekinumab have similar effectiveness in UC after anti-TNF failure. However, the efficacy of ustekinumab could be more impacted by prior therapeutic failures