Laser-pulse-shape control of seeded QED cascades

QED cascades are complex avalanche processes of hard photon emission and electron-positron pair creation driven by ultra-strong electromagnetic fields. They play a fundamental role in astrophysical environments such as a pulsars' magnetosphere, rendering an earth-based implementation with intense lasers attractive. In the literature, QED cascades were also predicted to limit the attainable intensity in a set-up of colliding laser beams in a tenuous gas such as the residual gas of a vacuum chamber, therefore severely hindering experiments at extreme field intensities. Here, we demonstrate that the onset of QED cascades may be either prevented even at intensities around 10^{26}\text{ W/cm^{2}} with tightly focused laser pulses and low-$Z$ gases, or facilitated at intensities below 10^{24}\text{ W/cm^{2}} with enlarged laser focal areas or high-$Z$ gases. These findings pave the way for the control of novel experiments such as the generation of pure electron-positron-photon plasmas from laser energy, and for probing QED in the extreme-intensity regime where the quantum vacuum becomes unstable.Comment: 11 pages, 3 figures, 1 tabl

Genetic determinants of cell sensitization to parvovirus H-1-induced activation of non-apoptotic death pathways

Gliomas are the most common brain cancers, characterized by an exceptionally wide cellular heterogeneity and extreme migratory features. The structural development of these neoplasms renders surgical removal of the tumoral mass almost prohibitive and inefficient. Moreover, these tumors are often resistant to chemotherapy treatments as a result of the onset of survival mechanisms occurring during astrocytes malignant transformation and counteracting the induction of apoptotic cell death. An alternative therapeutic approach relies on the use of autonomous parvoviruses. These small, non enveloped, single-stranded DNA viruses are endowed with the capacity to kill malignant cells while being non-cytopathic towards healthy tissues. In particular, recent analyses on low passage cultures of human gliomas have demonstrated that the rodent parvovirus H-1 (H-1PV) induces death in cells resistant to conventional anticancer compounds. Among these, NCH82 cells have been chosen in this study to investigate the mechanisms of parvovirus H-1-induced glioma cell death. It has been observed that H-1PV triggers the formation of autophagic vesicles that are eventually involved in the cytosolic activation of lysosomal cathepsins B and L. The virus promotes efficient killing even in glioma cells overexpressing Bcl-2, an oncogene interfering with both apoptosis and autophagy induction. Besides, H-1PV-induced cathepsin B cytosolic activity is favoured by the down-regulation of cystatin B and C, two cathepsins inhibitors, and modulates caspase 3 induction. Glioma cells are protected from the viral lytic effect by autophagy inhibition, cathepsin B or L inactivation or cystatin B overexpression. Finally, cathepsin B in vivo activation upon parvovirus H-1 infection is associated with the regression of rat glioma cells intracranially implanted into recipient animals. To set the basis for an extensive future study on the identification of the key genetic alterations that render tumor cells permissive to H-1PV, a preliminary analysis has been conducted on rat embryo fibroblasts (REFs). Different immortalized and transformed phenotypes have been induced in these cells by overexpressing c-myc, SV40 large T antigen and activated Ha-ras oncogenes, or by inactivating the anti-oncogene p53. Programmed cell death activation has been further analyzed in this model system to correlate the genetic determinants of H-1PV sensitiveness with specific molecular events leading to virus-induced cell killing. This work demonstrates that c-myc overexpression is sufficient to render REFs permissive to H-1PV-mediated cytolysis. While the virus accomplishes cytosuppression of ras*/p53dn-transformed REFs by activating classical apoptosis, it triggers in all the other transfectants a non-apoptotic death pathway characterized by the cytosolic accumulation of autophagic vesicles and active cathepsin B. These observations indicate parvovirus H-1 as a potential novel therapeutic tool for cancer treatment through its ability to efficiently hijack both autophagic/cathepsins and apoptotic pathways, thus jeopardizing tumor cells survival

Radiation Reaction Effects on Electron Nonlinear Dynamics and Ion Acceleration in Laser-solid Interaction

Radiation Reaction (RR) effects in the interaction of an ultra-intense laser pulse with a thin plasma foil are investigated analytically and by two-dimensional (2D3P) Particle-In-Cell (PIC) simulations. It is found that the radiation reaction force leads to a significant electron cooling and to an increased spatial bunching of both electrons and ions. A fully relativistic kinetic equation including RR effects is discussed and it is shown that RR leads to a contraction of the available phase space volume. The results of our PIC simulations are in qualitative agreement with the predictions of the kinetic theory

Combining RNAi and in vivo confocal microscopy analysis of the photoconvertible fluorescent protein Dendra2 to study a DNA repair protein.

Clinical approaches for tumor treatment often rely on combination therapy where a DNA damaging agent is used in combination with a DNA repair protein inhibitor. For this reason, great efforts have been made during the last decade to identify inhibitors of DNA repair proteins or, alternatively, small molecules that specifically alter protein stability or trafficking. Unfortunately, when studying these drug candidates, classical biochemical approaches are prone to artifacts. The apurinic/apyrimidinic endonuclease (APE1) protein is an essential component of the base excision repair (BER) pathway that is responsible for repairing DNA damage caused by oxidative and alkylating agents. In this work, we combined conditional gene expression knockdown of APE1 protein by RNA interference (RNAi) technology with re-expression of an ectopic recombinant form of APE1 fused with the photoconvertible fluorescent protein (PCFP) Dendra2. Dendra2 did not alter the subcellular localization or endonuclease activity of APEI. We calculated APE1 half-life and compared these results with the classical biochemical approach, which is based on cycloheximide (CHX) treatment. In conclusion, we combined RNAi and in vivo confocal microscopy to study a DNA repair protein demonstrating the feasibility and the advantage of this approach for the study of the cellular dynamic of a DNA repair protei

MeltingPlot, a user-friendly online tool for epidemiological investigation using High Resolution Melting data

BACKGROUND: The rapid identification of pathogen clones is pivotal for effective epidemiological control strategies in hospital settings. High Resolution Melting (HRM) is a molecular biology technique suitable for fast and inexpensive pathogen typing protocols. Unfortunately, the mathematical/informatics skills required to analyse HRM data for pathogen typing likely limit the application of this promising technique in hospital settings.RESULTS: MeltingPlot is the first tool specifically designed for epidemiological investigations using HRM data, easing the application of HRM typing to large real-time surveillance and rapid outbreak reconstructions. MeltingPlot implements a graph-based algorithm designed to discriminate pathogen clones on the basis of HRM data, producing portable typing results. The tool also merges typing information with isolates and patients metadata to create graphical and tabular outputs useful in epidemiological investigations and it runs in a few seconds even with hundreds of isolates.AVAILABILITY: https://skynet.unimi.it/index.php/tools/meltingplot/ .CONCLUSIONS: The analysis and result interpretation of HRM typing protocols can be not trivial and this likely limited its application in hospital settings. MeltingPlot is a web tool designed to help the user to reconstruct epidemiological events by combining HRM-based clustering methods and the isolate/patient metadata. The tool can be used for the implementation of HRM based real time large scale surveillance programs in hospital settings

Telomere Length Variation in Juvenile Acute Myocardial Infarction.

Leukocyte telomere length (LTL) provides a potential marker of biological age, closely related to the endothelial dysfunction and consequently to the atherosclerotic process. To investigate the relationship between the LTL and the risk of premature acute myocardial infarction and to evaluate the predictive value of LTL on the onset of major cardiovascular events, 199 patients from 18 to 48 years old with first diagnosis of acute myocardial infarction were enrolled and were matched with 190 controls for sex and age (± 1 year). Clinical data and coronary artery disease were evaluated at enrollment and at follow up. LTL was measured at enrollment using a quantitative PCR-based method. No significant differences were observed in LTL between cases and controls (p = 0.20) and with the presence of coronary artery disease in patients (p = 0.47). Hypercholesterolemic cases presented LTL significantly longer than cases without hypercholesterolemia (t/s: 0.82 ± 0.16 p = 0.79 and t/s norm: 0.79 ± 0.19 p = 0.01), as confirmed in multivariate regression analysis (p = 0.005, β = 0.09). Furthermore, multivariate regression analysis showed LTL significantly shorter in hypertensive cases than in normotensive cases (p = 0.04, β = -0.07). One hundred seventy-one cases (86%) ended the average follow up of 9 ± 5 years, 92 (54%) presented a major cardiovascular event. At multivariate regression analysis the LTL detected at enrollment did not represent a predictive factor of major cardiovascular events nor it significantly impacted with cumulative events. Based on present cohort of young Italian patients, the LTL did not represent a marker of acute myocardial infarction nor had a predictive role at medium term follow up

Trends and safety of bariatric revisional surgery in Italy: multicenter, prospective, observational study

Background: revisional bariatric surgery (RBS) represents a further solution for patients who experience inadequate weight loss (IWL) following primary bariatric surgery (BS) or significant weight regain (WR) following initial satisfactory response. RBS guidelines are lacking; however, an increased trend in further BS offerings has been reported recently. Objective: analyze trend, mortality, complication, readmission, and reoperation rates for any reason at 30 days after RBS in Italy. Setting: ten Italian high-volume BS centers (university hospitals and private centers). Methods: prospective, observational, multicenter study enrolling patients undergoing RBS between October 1, 2021, and March 31, 2022, registering reasons for RBS, technique, mortality, intraoperative and perioperative complications, readmissions, and reinterventions for any reason. Patients undergoing RBS during the same calendar interval in 2016-2020 were considered control patients. Results: a total of 220 patients were enrolled and compared with 560 control-group patients. Mortality was .45% versus .35% (n.s), with an overall mortality of .25%, while open surgery or conversion to open surgery was registered in 1%. No difference was found for mortality, morbidity, complications, readmission (1.3%), and reoperation rates (2.2%). IWL/WR was the most frequent cause, followed by gastroesophageal reflux disease; Roux-en-Y gastric bypass was the most used revisional procedure (56%). Sleeve gastrectomy was the most revised procedure in the study group, while gastric banding was the most revised in the control group. RBS represents up to 9% of the total BS in the Italian participating centers. Conclusions: laparoscopy represents the standard approach for RBS, which appears safe. Current Italian trends show a shift toward sleeve gastrectomy being the most revised procedure and Roux-en-Y gastric bypass being the most frequent revisional procedure

CHD8 suppression impacts on histone H3 lysine 36 trimethylation and alters RNA alternative splicing

Disruptive mutations in the chromodomain helicase DNA-binding protein 8 gene (CHD8) have been recurrently associated with autism spectrum disorders (ASDs). Here we investigated how chromatin reacts to CHD8 suppression by analyzing a panel of histone modifications in induced pluripotent stem cell-derived neural progenitors. CHD8 suppression led to significant reduction (47.82%) in histone H3K36me3 peaks at gene bodies, particularly impacting on transcriptional elongation chromatin states. H3K36me3 reduction specifically affects highly expressed, CHD8-bound genes and correlates with altered alternative splicing patterns of 462 genes implicated in ‘regulation of RNA splicing’ and ‘mRNA catabolic process’. Mass spectrometry analysis uncovered a novel interaction between CHD8 and the splicing regulator heterogeneous nuclear ribonucleoprotein L (hnRNPL), providing the first mechanistic insights to explain the CHD8 suppression-derived splicing phenotype, partly implicating SETD2, a H3K36me3 methyltransferase. In summary, our results point toward broad molecular consequences of CHD8 suppression, entailing altered histone deposition/maintenance and RNA processing regulation as important regulatory processes in ASD

Severe acute respiratory syndrome coronavirus 2 infection leads to Tau pathological signature in neurons

COVID-19 has represented an issue for global health since its outbreak in March 2020. It is now evident that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in a wide range of long-term neurological symptoms and is worryingly associated with the aggravation of Alzheimer’s disease. Little is known about the molecular basis of these manifestations. Here, several strain variants were used to infect SH-SY5Y neuroblastoma cells and K18-hACE C57BL/6J mice. The Tau phosphorylation profile and aggregation propensity upon infection were investigated on cellular extracts, subcellular fractions, and brain tissue. The viral proteins spike, nucleocapsid, and membrane were overexpressed in SH-SY5Y cells, and the direct interaction and effect on Tau phosphorylation were checked using immunoblot experiments. Upon infection, Tau is phosphorylated at several pathological epitopes associated with Alzheimer’s disease and other tauopathies. Moreover, this event increases Tau’s propensity to form insoluble aggregates and alters its subcellular localization. Our data support the hypothesis that SARS-CoV-2 infection in the central nervous system triggers downstream effects altering Tau function, eventually leading to the impairment of neuronal function

Nationwide consensus on the clinical management of treatment-resistant depression in Italy: a Delphi panel

Background: Treatment-resistant depression (TRD) is defined by the European Medicines Agency as a lack of clinically meaningful improvement after treatment, with at least two different antidepressants. Individual, familiar, and socio-economic burden of TRD is huge. Given the lack of clear guidelines, the large variability of TRD approaches across different countries and the availability of new medications to meet the need of effective and rapid acting therapeutic strategies, it is important to understand the consensus regarding the clinical characteristics and treatment pathways of patients with TRD in Italian routine clinical practice, particularly in view of the recent availability of esketamine nasal spray. Methods: A Delphi questionnaire with 17 statements (with a 7 points Likert scale for agreement) was administered via a customized web-based platform to Italian psychiatrists with at least 5 years of experience and specific expertise in the field of depression. In the second-round physicians were asked to answer the same statements considering the interquartile range of each question as an index of their colleagues' responses. Stata 16.1 software was used for the analyses. Results: Sixty panellists, representative of the Italian territory, answered the questionnaire at the first round. For 8/17 statements more than 75% of panellists reached agreement and a high consensus as they assigned similar scores; for 4 statements the panellists assigned similar scores but in the middle of the Likert scale showing a moderate agreement with the statement, while for 5 statements there was indecision in the agreement and low consensus with the statement. Conclusions: This Delphi Panel showed that there is a wide heterogeneity in Italy in the management of TRD patients, and a compelling need of standardised strategies and treatments specifically approved for TRD. A high level of consensus and agreement was obtained about the importance of adding lithium and/or antipsychotics as augmentation therapies and in the meantime about the need for long-term maintenance therapy. A high level of consensus and agreement was equally reached for the identification of esketamine nasal spray as the best option for TRD patients and for the possibility to administrate without difficulties esketamine in a community outpatient setting, highlighting the benefit of an appropriate educational support for patients