Kernel-based testing for single-cell differential analysis.

Single-cell technologies offer insights into molecular feature distributions, but comparing them poses challenges. We propose a kernel-testing framework for non-linear cell-wise distribution comparison, analyzing gene expression and epigenomic modifications. Our method allows feature-wise and global transcriptome/epigenome comparisons, revealing cell population heterogeneities. Using a classifier based on embedding variability, we identify transitions in cell states, overcoming limitations of traditional single-cell analysis. Applied to single-cell ChIP-Seq data, our approach identifies untreated breast cancer cells with an epigenomic profile resembling persister cells. This demonstrates the effectiveness of kernel testing in uncovering subtle population variations that might be missed by other methods.

Neurological outcome of cardiac arrest patients in mountain areas: An analysis of the Northern French Alps Emergency Network.

BACKGROUND: Mountainous areas pose a challenge for the out-of-hospital cardiac arrest (OHCA) chain of survival. Survival rates for OHCAs in mountainous areas may differ depending on the location. Increased survival has been observed compared to standard location when OHCA occurred on ski slopes. Limited data is available about OHCA in other mountainous areas. The objective was to compare the survival rates with a good neurological outcome of OHCAs occurring on ski slopes (On-S) and off the ski slopes (OffS) compared to other locations (OL). METHODS: Analysis of prospectively collected data from the cardiac arrest registry of the Northern French Alps Emergency Network (RENAU) from 2015 to 2021. The RENAU corresponding to an Emergency Medicine Network between all Emergency Medical Services and hospitals of 3 counties (Isère, Savoie, Haute-Savoie). The primary outcome was survival at 30 days with a Cerebral Performance Category scale (CPC) of 1 or 2 (1: Good Cerebral Performance, 2: Moderate Cerebral Disability). RESULTS: A total of 9589 OHCAs were included: 213 in the On-S group, 141 in the Off-S group, and 9235 in the OL group. Cardiac etiology was more common in On-S conditions (On-S: 68.9% vs OffS: 51.1% vs OL: 66.7%, p < 0.001), while Off-S cardiac arrests were more often due to traumatic circumstances (OffS: 39.7% vs On-S: 21.7% vs OL: 7.7%, p < 0.001). Automated external defibrillator (AED) use before rescuers' arrival was lower in the Off-S group than in the other two groups (On-S: 15.2% vs OL: 4.5% vs OffS: 3.7%; p < 0.002). The first AED shock was longer in the Off-S group (median time in minutes: OffS: 22.0 (9.5-35.5) vs On-S: 10.0 (3.0-19.5) vs OL: 16.0 (11.0-27.0), p = 0.03). In multivariate analysis, on-slope OHCA remained a positive factor for 30-day survival with a CPC score of 1 or 2 with a 1.96 adjusted odds ratio (95% confidence interval (CI), 1.02-3.75, p = 0.04), whereas off-slope OHCA had an 0.88 adjusted odds ratio (95% CI, 0.28-2.72, p = 0.82). CONCLUSIONS: OHCAs in ski-slopes conditions were associated with an improvement in neurological outcomes at 30 days, whereas off-slopes OHCAs were not. Ski-slopes rescue patrols are efficient in improving outcomes.

Patient eligibility for thrombectomy after acute stroke: Northern French Alps database analysis.

BACKGROUND: Since 2015, the emergence of mechanical thrombectomy as standard care in acute stroke has involved organizational changes not only for stroke centers, but also for entire emergency regional networks. The aim of our study was to assess the proportion of ischemic stroke patients, admitted to stroke units in the Northern French Alps within the first 6h of onset, eligible for thrombectomy. METHODS: This study retrospectively analyzed the clinical and radiological data of all acute stroke patients hospitalized at three stroke units of the Northern French Alps Emergency Network (RENAU) in 2014. Eligible patients had proximal arterial occlusions of the anterior and posterior cerebral circulation, as confirmed by brain imaging, which could be treated by thrombectomy within 6h of symptom onset. RESULTS: Of the 435 cases of acute ischemic stroke, 152 patients were treated by intravenous thrombolysis (IV rtPA). Of these patients, 83 (55%) had intracranial occlusions and were eligible for combined thrombectomy. Of the 283 patients not treatable by IV rtPA, 32 patients (11%) were eligible for primary thrombectomy. CONCLUSION: Thrombectomy could be performed in 26% of our acute ischemic stroke patients (n=115/435), and a large increase in endovascular procedures is expected over the next few years that will require close collaboration among all partners in the emergency networks. Using our RENAU stroke database, it will be possible to compare various factors contributing to effective activity.

PRC2-independent chromatin compaction and transcriptional repression in cancer.

The silencing of large chromosomal regions by epigenetic mechanisms has been reported to occur frequently in cancer. Epigenetic marks, such as histone methylation and acetylation, are altered at these loci. However, the mechanisms of formation of such aberrant gene clusters remain largely unknown. Here, we show that, in cancer cells, the epigenetic remodeling of chromatin into hypoacetylated domains covered with histone H3K27 trimethylation is paralleled by changes in higher-order chromatin structures. Using fluorescence in situ hybridization, we demonstrate that regional epigenetic silencing corresponds to the establishment of compact chromatin domains. We show that gene repression is tightly correlated to the state of chromatin compaction and not to the levels of H3K27me3-its removal through the knockdown of EZH2 does not induce significant gene expression nor chromatin decompaction. Moreover, transcription can occur with intact high-H3K27me3 levels; treatment with histone deacetylase inhibitors can relieve chromatin compaction and gene repression, without altering H3K27me3 levels. Our findings imply that compaction and subsequent repression of large chromatin domains are not direct consequences of PRC2 deregulation in cancer cells. By challenging the role of EZH2 in aberrant gene silencing in cancer, these findings have therapeutical implications, notably for the choice of epigenetic drugs for tumors with multiple regional epigenetic alterations.

Lipoperoxidation in plasma and red blood cells of patients undergoing haemodialysis: vitamins A, E, and iron status.

In 14 patients undergoing haemodialysis, lipoperoxidation (LPO) processes were determined in plasma and red blood cells (RBC) before and after a dialysis session by determining (a) the direct substrate, polyunsaturated fatty acids (PUFA); (b) the end product of LPO, malondialdehyde (MDA); and (c) the hydrophobic antioxidant systems, vitamins A and E. In plasma before dialysis, linoleic and arachidonic acid, and the antioxidant vitamin E, were significantly lowered as compared to the healthy controls (p < 0.05). On the contrary, the free MDA level was enhanced (p < 0.05). These results were emphasized by a dialysis session. In RBC of these patients, no difference in linoleic acid, free MDA, or vitamin E level were observed before or after dialysis when compared to controls. However, only vitamin A was significantly higher in haemodialysis patients (before and after dialysis) and in renal failure patients (p < 0.05) than in the healthy control group. The present results suggest that increased RBC vitamin A may offer some degree of protection against oxidative stress in erythrocytes, but not in plasma where LPO is demonstrated.

Use of red blood cell indices (MCV, MCH, RDW) in monitoring chronic hemodialysis patients treated with recombinant erythropoietin.

Human recombinant erythropoietin (rHu-Epo) is now extensively used in chronic renal failures; this treatment, resulting in a correction of the severe anemias seen in hemodialysed patients, may in turn lead to a resistance to rHu-Epo therapy by reason of the shortage of erythropoiesis factors, such as iron, vitamin B12 and folates. The utility of the red cell indices (MCV, MCH, RDW) for detection of early iron, folate and B12 deficiencies was studied in eighteen hemodialysed patients with end-stage renal failure treated with rHu-Epo; Microcytosis (MCV < 80 fl) was found ineffective in detecting iron deficiencies as well as macrocytosis (MCV > 100 fl) in folate and B12 deficiencies, partly due to the high incidence of associated iron and folate deficiencies. Lowered MCH (< 27 pg) was not more efficient than microcytosis in detecting early iron deficiencies. Increased RDW was the most sensitive feature for folate, iron and B12 deficiencies with respective sensitivities of 62.5%, 72% and 75%. The global specificity for detecting all deficiencies was 74%. However, high RDW values were not indicative of any type of deficiency; it may thus be concluded that RDW is a non expensive, non invasive and sensitive test, which allows a selection of hemodialysed patients treated with rHu-Epo for a complete investigation program, in order to detect early iron, B12 and folate deficiencies.

Increase of erythrocyte resistance to hemolysis and modification of membrane lipids induced by hemodialysis.

Mechanical fragility, deformability and lipid composition of erythrocyte membranes were studied in 22 uremic dialysed patients before and after dialysis in comparison to controls. While deformability was not affected by a dialysis session, osmotic and saponin resistances to hemolysis were significantly increased after dialysis (p less than 0.001). The lipid composition of erythrocyte membranes was also altered during dialysis, with a notable increase in cholesterol and a different phospholipid distribution, i.e. phosphatidylcholine and sphingomyelin significantly decreased (p less than 0.001). Likewise, the fatty acid distribution showed large variations with an increase in polyunsaturated fatty acid. The acute effect of dialysis on the membrane lipid composition seems to be linked to erythrocyte alterations. Its significance is discussed in relation to the asymmetric transverse distribution of phospholipids previously described in human erythrocyte.