Long COVID and gut candidiasis:What is the existing relationship?

Since the beginning of the coronavirus disease(COVID)2019 pandemic,thou-sands of articles on the topic have been published,and although there is a growing trend of research on another associated condition,long coronavirus disease,important points still remain to be clarified in this respect.Robust evidence has suggested a relevant link between new clinical discoveries and molecular mechanisms that could be associated with the manifestations of different signs and symptoms involving cases of long COVID.However,one of the existing gaps that requires further investigation concerns a possible rela-tionship between gut candidiasis and long COVID.While recent studies also suggest an interplay between the occurrence of these two conditions,it is not yet fully clear how this may happen,as well as the specifics regarding the possible pathophysiological mechanisms involved.In this connection and with the advent of a potential strengthening of the body of evidence supporting the hypothesis of a link between gut candidiasis and long COVID,a better understanding of the clinical presentation,pathophysiology and clinical management of such a relationship should be essential and useful for both,additional advances towards more targeted research and appropriate case management.Knowing more about the signs,symptoms,and complications associated with cases of long COVID is essential in order to more effectively mitigate the related burden and provide a higher quality of care and life for the affected population.In light of this and the need for better outcomes,here we review and discuss the content on different aspects of long COVID,including its pathophysiology and the existing evidence of a potential relationship between such a condition and gut candidiasis,as well as suggest propositions for future related research.INTRODUCTION Long coronavirus disease(COVID)is a condition characterized by the emergence of new symptoms or the persistence of existing symptoms for at least two months,three months after the initial infection[1].Although such a condition has initially been extensively studied,there are still many contradictions between the findings and methodologies of different related research articles[2,3].Within this context and since the middle of the COVID-19 pandemic,important studies have been published in the literature reporting the occurrence of fungal infections among COVID-19 patients[4,5],including mucormycosis,and oral candidiasis[6].On the other hand,evidence on a possible relationship between gut candidiasis and long COVID is still recent[7].Indeed,a marked gastrointestinal(GI)fungal dysbiosis together with perturbation of the lung-gut axis has been observed in severe COVID-19 patients.This combined with neutrophilia and an exacerbated worsening of the inflammatory response,which can be implicated in the acute and chronic immunopathology of such a viral disease[7,8].Furthermore,persistent changes in the immune system may also occur,resulting in a possible relationship with the occurrence of long COVID[7].However,more targeted evidence is still scarce and the specific topic related to gut candidiasis has been the subject of little discussion.In response to this,in this article we discuss general aspects of long COVID,the inherent pathophysiology and current evidence of a potential relationship between this condition and gut candidiasis,in addition to providing recommendations for future research.ACKNOWLEDGEMENTS Tovani-Palone MR thanks the Saveetha Institute of Medical and Technical Sciences for supporting this study.

Synaptic alterations as a common phase in neurological and neurodevelopmental diseases: JNK is a key mediator in synaptic changes

Brain synapses play a key role in neuronal communication:this“conversation”is at the basis of all brain activities and synaptic dysfunction leads to brain disorders.We study the modulators of this crucial synaptic function and we here present the evidence supporting the c-Jun N-terminal kinase(JNK)pathway as a pivotal actor in this scenario.

Indian medicinal plants are effective in the treatment and management of COVID-19

Indian medicinal plants are referred to as the“nectar of life”owing to their phytochemicals and bioactive complexes that are beneficial in treating diseases.Coronavirus disease 2019(COVID-19)is a global health issue without any proper medication.The indigenous plants of India can be exploited to control the precise signs of SARS-CoV-2.The Ministry of AYUSH(Ayurveda,Yoga and Naturopathy,Unani,Siddha,and Homeopathy)has advised routine usage of medicinal plants for COVID-19.Medicinal plants like Zingiber officinalis,Azadirachta indica,Ocimum sanctum,Nigella sativa,Withania somnifera,Curcuma longa,Piper nigrum,Allium sativum,Tinospora cordifolia,etc.have immunity-boosting,antiviral,antibacterial,antioxidant and anti-inflammatory actions that can suppress and treat symptoms of COVID-19.In vitro,in vivo as well as in silico validation,these phytochemicals can help us to manage and treat COVID-19 disease.This integration of traditional knowledge in the prophylaxis of corona infection and current skills validating it for the development of precise and powerful therapeutic approaches will more efficiently resolve different clinical aspects of COVID-19.The review focuses on both traditional and emergent methods to prevent and treat COVID-19 with various Indian medicinal plants along with their phytochemicals.

Advancing immunosuppression in liver transplantation: A narrative review

Immunosuppression is essential to ensure recipient and graft survivals after liver transplantation(LT). However, our understanding and management of the immune system remain suboptimal. Current immunosuppressive therapy cannot selectively inhibit the graft-specific immune response and entails a significant risk of serious side effects, i.e., among others, de novo cancers, infections, cardiovascular events, renal failure, metabolic syndrome, and late graft fibrosis, with progressive loss of graft function. Pharmacological research, aimed to develop alternative immunosuppressive agents in LT, is behind other solidorgan transplantation subspecialties, and, therefore, the development of new compounds and strategies should get priority in LT. The research trajectories cover mechanisms to induce T-cell exhaustion, to inhibit co-stimulation, to mitigate non-antigen-specific inflammatory response, and, lastly, to minimize the development and action of donor-specific antibodies. Moreover, while cellular modulation techniques are complex, active research is underway to foster the action of T-regulatory cells, to induce tolerogenic dendritic cells, and to promote the function of B-regulatory cells. We herein discuss current lines of research in clinical immunosuppression, particularly focusing on possible applications in the LT setting.

The challenge of molecular selection in liver-limited metastatic colorectal cancer for surgical resection: a systematic review and meta-analysis in the context of current and future approaches

Objectives:Treatment of metastatic colorectal cancer(mCRC)includes resection of liver metastases(LM),however,no validated biomarker identifies patients most likely to benefit from this procedure.This meta-analysis aimed to assess the impact of the most relevant molecular alterations in cancer-related genes of CRC(i.e.,RAS,BRAF,SMAD4,PIK3CA)as prognostic markers of survival and disease recurrence in patients with mCRC surgically treated by LM resection.Methods:A systematic literature review was performed to identify studies reporting data regarding survival and/or recurrence in patients that underwent complete liver resection for CRC LM,stratified according to RAS,BRAF,PIK3CA,and SMAD4 mutational status.Hazard ratios(HRs)from multivariate analyses were pooled in the meta-analysis and various adjustment strategies for confounding factors were combined.The search was conducted in numerous databases,including MEDLINE(PubMed),Embase,Cumulative Index to Nursing and Allied Health Literature(CINAHL)(EBSCO host),and WHO Global Index Medicus,through March 18th,2022.Meta-analyses,editorials,letters to the editor,case reports,studies on other primary cancers,studies with primary metastatic sites other than the liver,studies lacking specific oncological outcome variables or genetic data,non-English language studies,and studies omitting residual disease data from liver metastasectomy were excluded.The remaining 47 studies were summarized in a descriptive table which outlines the key characteristics of each study and final results were graphically presented.Results:RAS mutation status was negatively associated with overall survival(OS)(HR,1.68;95%CI,1.54–1.84)and recurrence free survival(RFS)(HR,1.46;95%CI,1.33–1.61).A negative association was also found for BRAF regarding OS(HR,2.64;95%CI,2.15–3.24)and RFS(HR,1.89;95%CI,1.32–2.73)and SMAD4 regarding OS(HR,1.93;95%CI,1.56–2.38)and RFS(HR,1.95;95%CI,1.31–2.91).For PIK3CA only three studies were eligible and no significant association with either OS or RFS could be highlighted.Conclusion:RAS,BRAF,and SMAD4 are negatively associated with OS and RFS in patients undergoing curative liver metastasectomy from colorectal cancer.No conclusion can be drawn for PIK3CA due to the limited literature availability.These data support the integration of RAS,BRAF,and SMAD4 mutational status in the surgical decision-making for colorectal liver metastasis.Nevertheless,we have to consider several limitations,the major ones being the pooling of results from studies that evaluated patient outcomes as either disease-free survival(DFS)or RFS;the inclusion of patients with minimal residual disease and unconsidered potential confounding factors,such as variability in resectability definitions,chemotherapy use,and a potential interaction between biological markers and pre-and post-resection pharmacological treatments.

Senescence in adipose-derived stem cells and its implications in nerve regeneration

Adult mesenchymal stem cells, specifically adipose-derived stem cells have self-renewal and multiple differentiation potentials and have shown to be the ideal candidate for therapeutic applications in regenerative medicine, particularly in peripheral nerve regeneration. Adipose-de- rived stem cells are easily harvested, although they may show the effects of aging, hence their potential in nerve repair may be limited by cellular senescence or donor age. Cellular senescence is a complex process whereby stem cells grow old as consequence of intrinsic events （e.g., DNA damage） or environmental cues （e.g., stressful stimuli or diseases）, which determine a permanent growth arrest. Several mechanisms are implicated in stem cell senescence, although no one is exclusive of the others. In this review we report some of the most important factors modulating the senescence process, which can influence adipose-derived stem cell morphology and function, and compromise their clinical application for peripheral nerve regenerative cell therapy.

Small bowel capsule endoscopy in 2007:Indications,risks and limitations

Capsule endoscopy has revoluzionized the study of the small bowel by providing a reliable method to evaluate, endoscopically, the entire small bowel. In the last six years several papers have been published exploring the possible role of this examination in different clinical conditions. At the present time capsule endoscopy is generally recommended as a third examination, after negative bidirectional endoscopy, in patients with obscure gastrointestinal bleeding. A growing body of evidence suggests also an important role for this examination in other clinical conditions such as Crohn＇s disease, celiac disease, small bowel polyposis syndromes or small bowel tumors. The main complication of this examination is the retention of the device at the site of a previously unknown small bowel stricture. However there are also some other open issues mainly due to technical limitations of this tool （which is not driven from remote control, is unable to take biopsies, to insufflate air, to suck fluids or debris and sometimes to correctly size and locate lesions）.The recently developed double balloon enteroscope, owing to its capability to explore a large part of the small bowel and to take targeted biopsies, although being invasive and time consuming, can overcome some limitations of capsule endoscopy. At the present time, in the majority of clinical conditions （i.e. obscure GI bleeding）, the winning strategy seems to be to couple these two techniques to explore the small bowel in a painless, safe and complete way （with capsule endoscopy） and to define and treat the lesions identified （with double balloon enteroscopy）.

Immune-mediated bile duct injury:The case of primary biliary cirrhosis

Autoimmune cholangitis would be the appropriate name to define the immune-mediated bile duct injury following the breakdown of tolerance to mitochondrial proteins and the appearance of serum autoantibodies and autoreactive T cells.Nevertheless,the conditionis universally named primary biliary cirrhosis(PBC).The disease etiology and pathogenesis remain largely unknown despite the proposed lines of evidence.One twin study and numerous epidemiology reportssuggest that both a susceptible genetic background and environmental factors determine disease onsetwhile a recent genome-wide association study proposed highly significant associations with several commongenetic polymorphisms in subgroups of patients.Specific infectious agents and chemicals may contribute to the disease onset and perpetuation in a geneticallysusceptible host,possibly through molecular mimicry.Importantly,several murine models have been proposed and include strains in which PBC is genetically determined or induced by immunization with chemicals and bacteria.From a pathogenetic standpoint,new exciting data have demonstrated the unique apoptotic features of bile duct cells that allow the mitochondrial autoantigens to be taken up in their intact form within apoptotic blebs.We are convinced that the application of the most recent molecular techniques will soon pro-vide developments in PBC etiology and pathogenesis with likely implications in diagnostics and therapeutics.

Endoscopic ultrasound-guided drainage of pancreatic fluid collections: The impact of evolving experience and new technologies in diagnosis and treatment over the last two decades

Background: Endoscopic ultrasound (EUS)-guided drainage is the preferred approach for drainage of pan- creatic uid collections (PFCs) due to the better experience and signi cant progress using newer stents and access devices during last decade. This study aimed to evaluate the role of the evolving experience and possible in uence of new technological devices on the outcome of patients evaluated for PFCs and submitted to EUS-guided drainage during two different periods: the early period at the beginning of experience when a standardized technique was used and the late period when the increased experience of the operator, combined with different stents quality were introduced in the management of PFCs. Methods: We retrospectively analyzed the clinical data of a cohort of 91 consecutive patients, who underwent EUS-guided drainage of symptomatic PFCs from October 2001 to September 2017. Demographic, therapeutic results, complications, and outcomes were compared between early years’ group (2001 2008) and late years’ group (2009 2017). Results: Endoscopic treatment was successfully achieved in 55.6% (20/36) of patients in the early years’ group, and in 96.4% (53/55) in the late years’ group. Eighteen patients (12 in early years’ and 6 in the late year’s group) required additional open surgery. Procedural complications were observed in 5 patients, 4 in early years’ and 1 in late years’ group. Mortality was registered in two patients (2.2%), one for each group. Conclusions: During our long-term survey using EUS-guided endoscopic drainage of PFCs, signi cantly better outcomes in term of improved success rate and decrease complications rate were observed during the late period.

Three-dimensional collagen-based scaffold model to study the microenvironment and drug-resistance mechanisms of oropharyngeal squamous cell carcinomas

Objective:Squamous cell carcinoma(SCC)represents the most common histotype of all head and neck malignancies and includes oropharyngeal squamous cell carcinoma(OSCC),a tumor associated with different clinical outcomes and linked to human papilloma virus(HPV)status.Translational research has few available in vitro models with which to study the different pathophysiological behavior of OSCCs.The present study proposes a 3-dimensional(3 D)biomimetic collagen-based scaffold to mimic the tumor microenvironment and the crosstalk between the extracellular matrix(ECM)and cancer cells.Methods:We compared the phenotypic and genetic features of HPV-positive and HPV-negative OSCC cell lines cultured on common monolayer supports and on scaffolds.We also explored cancer cell adaptation to the 3 D microenvironment and its impact on the efficacy of drugs tested on cell lines and primary cultures.Results:HPV-positive and HPV-negative cell lines were successfully grown in the 3 D model and displayed different collagen fiber organization.The 3 D cultures induced an increased expression of markers related to epithelial–mesenchymal transition(EMT)and to matrix interactions and showed different migration behavior,as confirmed by zebrafish embryo xenografts.The expression of hypoxia-inducible factor 1α(1α)and glycolysis markers were indicative of the development of a hypoxic microenvironment inside the scaffold area.Furthermore,the 3 D cultures activated drug-resistance signaling pathways in both cell lines and primary cultures.Conclusions:Our results suggest that collagen-based scaffolds could be a suitable model for the reproduction of the pathophysiological features of OSCCs.Moreover,3 D architecture appears capable of inducing drug-resistance processes that can be studied to better our understanding of the different clinical outcomes of HPV-positive and HPV-negative patients with OSCCs.

Synthesis of palladium-rhodium bimetallic nanoparticles for formic acid dehydrogenation

Herein,we report for the first time the synthesis of preformed bimetallic Pd-Rh nanoparticles with different Pd:Rh ratios(nominal molar ratio:80-20,60-40,40-60,20-80) and the corresponding Pd and Rh monometallic ones by sol immobilization using polyvinyl alcohol(PVA) as protecting agent and NaBH4 as reducing agent,using carbon nanofibers with high graphitization degree(HHT) as the desired support.The synthesized catalysts were characterized by means of Transmission Electron Microscopy(TEM) and inductively coupled plasma optical emission spectroscopy(ICP-OES).TEM shows that the average particle size of the Pd-Rh nanoparticles is the range of 3-4 nm,with the presence of few large agglomerated nanoparticles.For bimetallic catalysts,EDX-STEM analysis of individual nanoparticles demonstrated the presence of random-alloyed nanoparticles even in all cases Rh content is lower than the nominal one(calculated Pd:Rh molar ratio:90-10,69-31,49-51,40-60).The catalytic performance of the Pd-Rh catalysts was evaluated in the liquid phase dehydrogenation of formic acid to H2.It was found that Pd-Rh molar ratio strongly influences the catalytic performance.Pd-rich catalysts were more active than Rh-rich ones,with the highest activity observed for Pd90:Rh10(1792 h^(-1)),whereas Pd69:Rh31(921 h^(-1)) resulted the most stable during recycling tests.Finally,Pd90:Rh10 was chosen as a representative sample for the liquid-phase hydrogenation of muconic acid using formic acid as hydrogen donor,showing good yield to adipic acid.

Liver-side of inflammatory bowel diseases:Hepatobiliary and druginduced disorders

Hepatobiliary disorders are among the most common extraintestinal manifestations in inflammatory bowel diseases(IBD),both in Crohn’s disease and ulcerative colitis(UC),and therefore represent a diagnostic challenge.Immunemediated conditions include primary sclerosing cholangitis(PSC)as the main form,variant forms of PSC(namely small-duct PSC,PSC-autoimmune hepatitis overlap syndrome and IgG4-related sclerosing cholangitis)and granulomatous hepatitis.PSC is by far the most common,presenting in up to 8%of IBD patients,more frequently in UC.Several genetic foci have been identified,but environmental factors are preponderant on disease pathogenesis.The course of the two diseases is typically independent.PSC diagnosis is based mostly on typical radiological findings and exclusion of secondary cholangiopathies.Risk of cholangiocarcinoma is significantly increased in PSC,as well as the risk of colorectal cancer in patients with PSC and IBD-related colitis.No disease-modifying drugs are approved to date.Thus,PSC management is directed against symptoms and complications and includes medical therapies for pruritus,endoscopic treatment of biliary stenosis and liver transplant for end-stage liver disease.Other nonimmune-mediated hepatobiliary disorders are gallstone disease,whose incidence is higher in IBD and reported in up to one third of IBD patients,non-alcoholic fatty liver disease,pyogenic liver abscess and portal vein thrombosis.Druginduced liver injury(DILI)is an important issue in IBD,since most IBD therapies may cause liver toxicity;however,the incidence of serious adverse events is low.Thiopurines and methotrexate are the most associated with DILI,while the risk related to anti-tumor necrosis factor-αand anti-integrins is low.Data on hepatotoxicity of newer drugs approved for IBD,like anti-interleukin 12/23 and tofacitinib,are still scarce,but the evidence from other rheumatic diseases is reassuring.Hepatitis B reactivation during immunosuppressive therapy is a major concern in IBD,and adequate screening and vaccination is warranted.On the other hand,hepatitis C reactivation does not seem to be a real risk,and hepatitis C antiviral treatment does not influence IBD natural history.The approach to an IBD patient with abnormal liver function tests is complex due to the wide range of differential diagnosis,but it is of paramount importance to make a quick and accurate diagnosis,as it may influence the therapeutic management.

Non-invasive evaluation of intestinal disorders: The role of elastographic techniques

Over the recent years the non-invasive techniques for the evaluation of the small bowel have been playing a major role in the management of chronic intestinal diseases, such as inflammatory bowel diseases(IBD). The diagnostic performances of magnetic resonance imaging, computed tomography and ultrasound in the field of small bowel disorders, have been assessed and established for more than two decades. Newer sonographic techniques, such as strain elastography and shear wave elastography, have been put forward for the assessment of disease activity and characterization of IBD-related damage in the setting of Crohn's disease and other gastrointestinal disorders. The data from the preliminary research and clinical studies have shown promising results as regards the ability of elastographic techniques to differentiate inflammatory from fibrotic tissue. The distinction between IBD activity(inflammation) and IBD-related damage(fibrosis) is currently considered crucial for the assessment and management of patients. Moreover, all the elastographic techniques are currently being considered in the setting of other intestinal disorders(e.g., rectal tumors, appendicitis). The aim of this paper is to offer both a comprehensive narrative review of the non-invasive techniques available for the assessment of small-bowel disorders, with particular emphasis on inflammatory bowel diseases, and a summary of the current evidence on the use of elastographic techniques in this setting.

Glacial biodiversity of the southernmost glaciers of the European Alps(Clapier and Peirabroc,Italy)

We applied a multi-taxa approach integrating the co-occurrence of plants,ground beetles,spiders and springtails with soil parameters(temperatures and chemical characteristics)in order to describe the primary succession along two glacier forelands in the Maritime Alps(Italy),a hotspot of Mediterranean biodiversity.We compared these successions to those from Central Alps:Maritime glacier forelands markedly differ for their higher values of species richness and species turnover.Contrary to our expectation,Maritime glacier forelands follow a‘replacement change model’,like continental succession of Inner Alps and differently from other peripheral successions.We propose that the temperatures along these Mediterranean glacier forelands are warmer than those along other Alpine glacier forelands,which promote the faster species turnover.Furthermore,we found that early and mid successional stages of the investigated glaciers are richer in cold-adapted and endemic species than the later ones:we confirmed that the‘replacement change’model disadvantages pioneer,cold-adapted species.Given the overall correspondence among coldadapted and endemic species,the most threatened in this climate phase,our results raise new concerns about the extinction risk of these species.We also describe supraglacial habitat of Maritime glaciers demonstrating that supraglacial debris represents an environment decoupled from the regional climate and may have an important role as refugium for coldadapted and hygrophilous plant and animal species,whose survival can be threatened by climate change and by a rapid ecological succession in the adjacent forelands.

Dilation assisted stone extraction for complex biliary lithiasis:Technical aspects and practical principles

Common bile duct stones are frequently diagnosed worldwide and are one of the main indications for endoscopic retrograde cholangio-pancreatography.Endoscopic sphincterotomy(EST)has been used for the removal of bile duct stones for the past 40 years,providing a wide opening to allow extraction.Up to 15%of patients present with complicated choledocholithiasis.In this context,additional therapeutic approaches have been proposed such as endoscopic mechanical lithotripsy,intraductal or extracorporeal lithotripsy,or endoscopic papillary large balloon dilation(EPLBD).EPLBD combined with EST was introduced in 2003 to facilitate the passage of large or multiple bile duct stones using a balloon greater than 12 mm in diameter.EPLBD without EST was introduced as a simplified technique in 2009.Dilation-assisted stone extraction(DASE)is the combination of two techniques:EPLBD and sub-maximal EST.Several studies have reported this technique as safe and effective in patients with large bile duct stones,without any increased risk of adverse events such as pancreatitis,bleeding,or perforation.Nevertheless,it is difficult to analyze the outcomes of DASE because there are no standard techniques and definitions between studies.The purpose of this paper is to provide technical guidance and specific information about the main issues regarding DASE,based on current literature and daily clinical experience in biliary referral centers.

Digital liver biopsy:Bio-imaging of fatty liver for translational and clinical research

The rapidly growing field of functional, molecular and structural bio-imaging is providing an extraordinary new opportunity to overcome the limits of invasive liver biopsy and introduce a "digital biopsy" for in vivo study of liver pathophysiology. To foster the application of bio-imaging in clinical and translational research, there is a need to standardize the methods of both acquisition and the storage of the bio-images of the liver. It can be hoped that the combination of digital, liquid and histologic liver biopsies will provide an innovative synergistic tri-dimensional approach to identifying new aetiologies, diagnostic and prognostic biomarkers and therapeutic targets for the optimization of personalized therapy of liver diseases and liver cancer. A group of experts of different disciplines(Special Interest Group for Personalized Hepatology of the Italian Association for the Study of the Liver, Institute for Biostructures and Bio-imaging of the National Research Council and Bio-banking and Biomolecular Resources Research Infrastructure) discussed criteria, methods and guidelines for facilitating the requisite application of data collection. This manuscript provides a multi-Author review of the issue with special focus on fatty liver.

Urban Forest Digital Cadastre

Urban forests being part of the Natural Capital,they provide goods and services for humans,the ecosystem services that are necessary for their survival.Over recent years,the importance of ecosystem services within urban landscapes has grown steadily.Determining the amount and the value of the ecosystem services provided by the Urban Forest is the main goal of the“Digital Green Cadastre”(DGC),a project in progress of survey,classification and mapping of the urban,agricultural and natural green assets.The DGC records the types of green cover and soil characteristics and utilizes the calculation of the total leaf area for the quantitative analysis of the botanical heritage,environmental performance and ecosystem benefits,such as water runoff management,air pollutant removal and urban heat island reduction.The case study of Abbiategrasso-a small town in Italy-is reported.

A novel way to study the nuclear collective excitations

Typically, the unambiguous determination of the quantum numbers of nuclear states is a challenging task. Recently, it has been proposed to utilize to this aim vortex photons in the MeV energy region and, potentially, this could revolutionize nuclear spectroscopy because of the new and enhanced selectivity of this probe. Moreover, nuclei may become diagnostic tools for vortex photons. Still, some open questions have to be dealt with.Nuclei exhibit intricate excitation spectra. Indeed, not all states within these spectra are equally significant. Some are not sensitive to specific terms in the nuclear Hamiltonian or do not display novel features, so that investigating them is not helpful to enhance our overall understanding of nuclear structure. On the other hand, there are states that manifest themselves as prominent peaks, e.g., in the inelastic scattering spectra. Among the best examples are the so-called Giant Resonances that lie at energies of the order of tens of MeV [1].

Axonal tuning by GABA_(A) receptor unveils novel tricks from an old dog

In the last years,axonal conductance of action potential trains became a novel subject of study,changing the view of axons,from a static cable-like compartment to a more complex and dynamic system(Debanne et al.,2011).Axonal computation,indeed,is canonically constituted by the action of voltage-gated ion channels,such as the classic Na+and K+channels,but recent studies demonstrated that it can be modulated by the action of other ion channel pumps,and metabolic factors(Byczkowicz et al.,2019;Zang and Marder.

Observation of a single protein by ultrafast X-ray diffraction

The idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many.It was one of the arguments for building X-ray free-electron lasers.According to theory,the extremely intense pulses provide sufficient signal to dispense with using crystals as an amplifier,and the ultrashort pulse duration permits capturing the diffraction data before the sample inevitably explodes.This was first demonstrated on biological samples a decade ago on the giant mimivirus.Since then,a large collaboration has been pushing the limit of the smallest sample that can be imaged.The ability to capture snapshots on the timescale of atomic vibrations,while keeping the sample at room temperature,may allow probing the entire conformational phase space of macromolecules.Here we show the first observation of an X-ray diffraction pattern from a single protein,that of Escherichia coli GroEL which at 14 nm in diameter is the smallest biological sample ever imaged by X-rays,and demonstrate that the concept of diffraction before destruction extends to single proteins.From the pattern,it is possible to determine the approximate orientation of the protein.Our experiment demonstrates the feasibility of ultrafast imaging of single proteins,opening the way to single-molecule time-resolved studies on the femtosecond timescale.