Excitation and Inhibition Delays within a Feedforward Inhibitory Pathway Modulate Cerebellar Purkinje Cell Output in Mice.

The cerebellar cortex computes sensorimotor information from many brain areas through a feedforward inhibitory (FFI) microcircuit between the input stage, the granule cell (GC) layer, and the output stage, the Purkinje cells (PCs). Although in other brain areas FFI underlies a precise excitation versus inhibition temporal correlation, recent findings in the cerebellum highlighted more complex behaviors at GC-molecular layer interneuron (MLI)-PC pathway. To dissect the temporal organization of this cerebellar FFI pathway, we combined ex vivo patch-clamp recordings of PCs in male mice with a viral-based strategy to express Channelrhodopsin2 in a subset of mossy fibers (MFs), the major excitatory inputs to GCs. We show that although light-mediated MF activation elicited pairs of excitatory and inhibitory postsynaptic currents in PCs, excitation (E) from GCs and inhibition (I) from MLIs reached PCs with a wide range of different temporal delays. However, when GCs were directly stimulated, a low variability in E/I delays was observed. Our results demonstrate that in many recordings MF stimulation recruited different groups of GCs that trigger E and/or I, and expanded PC temporal synaptic integration. Finally, using a computational model of the FFI pathway, we showed that this temporal expansion could strongly influence how PCs integrate GC inputs. Our findings show that specific E/I delays may help PCs encoding specific MF inputs.SIGNIFICANCE STATEMENT Sensorimotor information is conveyed to the cerebellar cortex by mossy fibers. Mossy fiber inputs activate granule cells that excite molecular interneurons and Purkinje cells, the sole output of the cerebellar cortex, leading to a sequence of synaptic excitation and inhibition in Purkinje cells, thus defining a feedforward inhibitory pathway. Using electrophysiological recordings, optogenetic stimulation, and mathematical modeling, we demonstrated that different groups of granule cells can elicit synaptic excitation and inhibition with various latencies onto Purkinje cells. This temporal variability controls how granule cells influence Purkinje cell discharge and may support temporal coding in the cerebellar cortex.

An activator of voltage-gated K+ channels Kv1.1 as a therapeutic candidate for episodic ataxia type 1.

Loss-of-function mutations in the KCNA1(Kv1.1) gene cause episodic ataxia type 1 (EA1), a neurological disease characterized by cerebellar dysfunction, ataxic attacks, persistent myokymia with painful cramps in skeletal muscles, and epilepsy. Precision medicine for EA1 treatment is currently unfeasible, as no drug that can enhance the activity of Kv1.1-containing channels and offset the functional defects caused by KCNA1 mutations has been clinically approved. Here, we uncovered that niflumic acid (NFA), a currently prescribed analgesic and anti-inflammatory drug with an excellent safety profile in the clinic, potentiates the activity of Kv1.1 channels. NFA increased Kv1.1 current amplitudes by enhancing the channel open probability, causing a hyperpolarizing shift in the voltage dependence of both channel opening and gating charge movement, slowing the OFF-gating current decay. NFA exerted similar actions on both homomeric Kv1.2 and heteromeric Kv1.1/Kv1.2 channels, which are formed in most brain structures. We show that through its potentiating action, NFA mitigated the EA1 mutation-induced functional defects in Kv1.1 and restored cerebellar synaptic transmission, Purkinje cell availability, and precision of firing. In addition, NFA ameliorated the motor performance of a knock-in mouse model of EA1 and restored the neuromuscular transmission and climbing ability in Shaker (Kv1.1) mutant Drosophila melanogaster flies (Sh5). By virtue of its multiple actions, NFA has strong potential as an efficacious single-molecule-based therapeutic agent for EA1 and serves as a valuable model for drug discovery.

Overexpression of UCP4 in astrocytic mitochondria prevents multilevel dysfunctions in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is becoming increasingly prevalent worldwide. It represents one of the greatest medical challenges as no pharmacologic treatments are available to prevent disease progression. Astrocytes play crucial functions within neuronal circuits by providing metabolic and functional support, regulating interstitial solute composition, and modulating synaptic transmission. In addition to these physiological functions, growing evidence points to an essential role of astrocytes in neurodegenerative diseases like AD. Early-stage AD is associated with hypometabolism and oxidative stress. Contrary to neurons that are vulnerable to oxidative stress, astrocytes are particularly resistant to mitochondrial dysfunction and are therefore more resilient cells. In our study, we leveraged astrocytic mitochondrial uncoupling and examined neuronal function in the 3xTg AD mouse model. We overexpressed the mitochondrial uncoupling protein 4 (UCP4), which has been shown to improve neuronal survival in vitro. We found that this treatment efficiently prevented alterations of hippocampal metabolite levels observed in AD mice, along with hippocampal atrophy and reduction of basal dendrite arborization of subicular neurons. This approach also averted aberrant neuronal excitability observed in AD subicular neurons and preserved episodic-like memory in AD mice assessed in a spatial recognition task. These findings show that targeting astrocytes and their mitochondria is an effective strategy to prevent the decline of neurons facing AD-related stress at the early stages of the disease.

The challenge of infectious diseases consultations in the emergency department: an Italian nationwide survey.

Diagnosis and management of infectious diseases (ID) at the emergency department (ED) are challenging due to the peculiar setting and the available diagnostic tools. The involvement of an ID consultant has been described to improve clinical outcomes and antimicrobial stewardship (AMS) programs. An online survey was sent to 100 Italian Departments of Infectious Diseases affiliated with the Italian Society of Infectious Diseases and Tropical Medicine (SIMIT). The primary objective of our study was to describe the characteristics of ID services in Italian EDs to identify possible challenges and shortcomings and provide tips to improve the management of patients. Secondary objectives included the evaluation of diagnostic capability and the management of patients with suspected or confirmed ID. Seventy-six out of the 100 SIMIT centers, 32 (42.1%) of which were teaching hospitals, answered the survey. In 62 (82.7%) centers, consultations were performed by the IDs specialist on call. In 29 (38.2%) centers, there was a formal AMS program, and 32 (42.7%) had protocols for antibiotic use in the ED. Microbiological tests to be performed before starting antibiotic treatment in the ED were clearly defined in 44 (57.9%) hospitals. This survey highlighted several challenges in the current organization of ID consultations in Italian EDs.

Evaluation of Hydroxycarboxylic Acid Receptor 1 (HCAR1) as a Building Block for Genetically Encoded Extracellular Lactate Biosensors.

The status of lactate has evolved from being considered a waste product of cellular metabolism to a useful metabolic substrate and, more recently, to a signaling molecule. The fluctuations of lactate levels within biological tissues, in particular in the interstitial space, are crucial to assess with high spatial and temporal resolution, and this is best achieved using cellular imaging approaches. In this study, we evaluated the suitability of the lactate receptor, hydroxycarboxylic acid receptor 1 (HCAR1, formerly named GPR81), as a basis for the development of a genetically encoded fluorescent lactate biosensor. We used a biosensor strategy that was successfully applied to molecules such as dopamine, serotonin, and norepinephrine, based on their respective G-protein-coupled receptors. In this study, a set of intensiometric sensors was constructed and expressed in living cells. They showed selective expression at the plasma membrane and responded to physiological concentrations of lactate. However, these sensors lost the original ability of HCAR1 to selectively respond to lactate versus other related small carboxylic acid molecules. Therefore, while representing a promising building block for a lactate biosensor, HCAR1 was found to be sensitive to perturbations of its structure, affecting its ability to distinguish between related carboxylic molecules.

Increased responsiveness at the cerebellar input stage in the PRRT2 knockout model of paroxysmal kinesigenic dyskinesia.

PRoline-Rich Transmembrane protein-2 (PRRT2) is a recently described neuron-specific type-2 integral membrane protein with a large cytosolic N-terminal domain that distributes in presynaptic and axonal domains where it interacts with several presynaptic proteins and voltage-gated Na+ channels. Several PRRT2 mutations are the main cause of a wide and heterogeneous spectrum of paroxysmal disorders with a loss-of-function pathomechanism. The highest expression levels of PRRT2 in brain occurs in cerebellar granule cells (GCs) and cerebellar dysfunctions participate in the dyskinetic phenotype of PRRT2 knockout (KO) mice. We have investigated the effects of PRRT2 deficiency on the intrinsic excitability of GCs and the input-output relationships at the mossy fiber-GC synapses. We show that PRRT2 KO primary GCs display increased expression of Na+ channels, increased amplitude of Na+ currents and increased length of the axon initial segment, leading to an overall enhancement of intrinsic excitability. In acute PRRT2 KO cerebellar slices, GCs were more prone to action potential discharge in response to mossy fiber activation and exhibited an enhancement of transient and persistent Na+ currents, in the absence of changes at the mossy fiber-GC synapses. The results support a key role of PRRT2 expressed in GCs in the physiological regulation of the excitatory input to the cerebellum and are consistent with a major role of a cerebellar dysfunction in the pathogenesis of the PRRT2-linked paroxysmal pathologies.

Surviving COVID-19 in Bergamo province: a post-acute outpatient re-evaluation.

Bergamo province was badly hit by the coronavirus disease 2019 (COVID-19) epidemic. We organised a public-funded, multidisciplinary follow-up programme for COVID-19 patients discharged from the emergency department or from the inpatient wards of 'Papa Giovanni XXIII' Hospital, the largest public hospital in the area. As of 31 July, the first 767 patients had completed the first post-discharge multidisciplinary assessment. Patients entered our programme at a median time of 81 days after discharge. Among them, 51.4% still complained of symptoms, most commonly fatigue and exertional dyspnoea, and 30.5% were still experiencing post-traumatic psychological consequences. Impaired lung diffusion was found in 19%. Seventeen per cent had D-dimer values two times above the threshold for diagnosis of pulmonary embolism (two unexpected and clinically silent pulmonary thrombosis were discovered by investigating striking D-dimer elevation). Survivors of COVID-19 exhibit a complex array of symptoms, whose common underlying pathology, if any, has still to be elucidated: a multidisciplinary approach is fundamental, to address the different problems and to look for effective solutions.

Tocilizumab for patients with COVID-19 pneumonia. The single-arm TOCIVID-19 prospective trial.

BACKGROUND: Tocilizumab blocks pro-inflammatory activity of interleukin-6 (IL-6), involved in pathogenesis of pneumonia the most frequent cause of death in COVID-19 patients. METHODS: A multicenter, single-arm, hypothesis-driven trial was planned, according to a phase 2 design, to study the effect of tocilizumab on lethality rates at 14 and 30 days (co-primary endpoints, a priori expected rates being 20 and 35%, respectively). A further prospective cohort of patients, consecutively enrolled after the first cohort was accomplished, was used as a secondary validation dataset. The two cohorts were evaluated jointly in an exploratory multivariable logistic regression model to assess prognostic variables on survival. RESULTS: In the primary intention-to-treat (ITT) phase 2 population, 180/301 (59.8%) subjects received tocilizumab, and 67 deaths were observed overall. Lethality rates were equal to 18.4% (97.5% CI: 13.6-24.0, P = 0.52) and 22.4% (97.5% CI: 17.2-28.3, P < 0.001) at 14 and 30 days, respectively. Lethality rates were lower in the validation dataset, that included 920 patients. No signal of specific drug toxicity was reported. In the exploratory multivariable logistic regression analysis, older age and lower PaO2/FiO2 ratio negatively affected survival, while the concurrent use of steroids was associated with greater survival. A statistically significant interaction was found between tocilizumab and respiratory support, suggesting that tocilizumab might be more effective in patients not requiring mechanical respiratory support at baseline. CONCLUSIONS: Tocilizumab reduced lethality rate at 30 days compared with null hypothesis, without significant toxicity. Possibly, this effect could be limited to patients not requiring mechanical respiratory support at baseline. Registration EudraCT (2020-001110-38); clinicaltrials.gov (NCT04317092).

Endothelial injury and thrombotic microangiopathy in COVID-19: Treatment with the lectin-pathway inhibitor narsoplimab.

In COVID-19, acute respiratory distress syndrome (ARDS) and thrombotic events are frequent, life-threatening complications. Autopsies commonly show arterial thrombosis and severe endothelial damage. Endothelial damage, which can play an early and central pathogenic role in ARDS and thrombosis, activates the lectin pathway of complement. Mannan-binding lectin-associated serine protease-2 (MASP-2), the lectin pathway's effector enzyme, binds the nucleocapsid protein of severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2), resulting in complement activation and lung injury. Narsoplimab, a fully human immunoglobulin gamma 4 (IgG4) monoclonal antibody against MASP-2, inhibits lectin pathway activation and has anticoagulant effects. In this study, the first time a lectin-pathway inhibitor was used to treat COVID-19, six COVID-19 patients with ARDS requiring continuous positive airway pressure (CPAP) or intubation received narsoplimab under compassionate use. At baseline and during treatment, circulating endothelial cell (CEC) counts and serum levels of interleukin-6 (IL-6), interleukin-8 (IL-8), C-reactive protein (CRP) and lactate dehydrogenase (LDH) were assessed. Narsoplimab treatment was associated with rapid and sustained reduction of CEC and concurrent reduction of serum IL-6, IL-8, CRP and LDH. Narsoplimab was well tolerated; no adverse drug reactions were reported. Two control groups were used for retrospective comparison, both showing significantly higher mortality than the narsoplimab-treated group. All narsoplimab-treated patients recovered and survived. Narsoplimab may be an effective treatment for COVID-19 by reducing COVID-19-related endothelial cell damage and the resultant inflammation and thrombotic risk.

Cerebellar Development and Circuit Maturation: A Common Framework for Spinocerebellar Ataxias.

Spinocerebellar ataxias (SCAs) affect the cerebellum and its afferent and efferent systems that degenerate during disease progression. In the cerebellum, Purkinje cells (PCs) are the most vulnerable and their prominent loss in the late phase of the pathology is the main characteristic of these neurodegenerative diseases. Despite the constant advancement in the discovery of affected molecules and cellular pathways, a comprehensive description of the events leading to the development of motor impairment and degeneration is still lacking. However, in the last years the possible causal role for altered cerebellar development and neuronal circuit wiring in SCAs has been emerging. Not only wiring and synaptic transmission deficits are a common trait of SCAs, but also preventing the expression of the mutant protein during cerebellar development seems to exert a protective role. By discussing this tight relationship between cerebellar development and SCAs, in this review, we aim to highlight the importance of cerebellar circuitry for the investigation of SCAs.

Differential Coding Strategies in Glutamatergic and GABAergic Neurons in the Medial Cerebellar Nucleus.

The cerebellum drives motor coordination and sequencing of actions at the millisecond timescale through adaptive control of cerebellar nuclear output. Cerebellar nuclei integrate high-frequency information from both the cerebellar cortex and the two main excitatory inputs of the cerebellum: the mossy fibers and the climbing fiber collaterals. However, how nuclear cells process rate and timing of inputs carried by these inputs is still debated. Here, we investigate the influence of the cerebellar cortical output, the Purkinje cells, on identified cerebellar nuclei neurons in vivo in male mice. Using transgenic mice expressing Channelrhodopsin2 specifically in Purkinje cells and tetrode recordings in the medial nucleus, we identified two main groups of neurons based on the waveform of their action potentials. These two groups of neurons coincide with glutamatergic and GABAergic neurons identified by optotagging after Chrimson expression in VGLUT2-cre and GAD-cre mice, respectively. The glutamatergic-like neurons fire at high rate and respond to both rate and timing of Purkinje cell population inputs, whereas GABAergic-like neurons only respond to the mean population firing rate of Purkinje cells at high frequencies. Moreover, synchronous activation of Purkinje cells can entrain the glutamatergic-like, but not the GABAergic-like, cells over a wide range of frequencies. Our results suggest that the downstream effect of synchronous and rhythmic Purkinje cell discharges depends on the type of cerebellar nuclei neurons targeted.SIGNIFICANCE STATEMENT Motor coordination and skilled movements are driven by the permanent discharge of neurons from the cerebellar nuclei that communicate cerebellar computation to other brain areas. Here, we set out to study how specific subtypes of cerebellar nuclear neurons of the medial nucleus are controlled by Purkinje cells, the sole output of the cerebellar cortex. We could isolate different subtypes of nuclear cell that differentially encode Purkinje cell inhibition. Purkinje cell stimulation entrains glutamatergic projection cells at their firing frequency, whereas GABAergic neurons are only inhibited. These differential coding strategies may favor temporal precision of cerebellar excitatory outputs associated with specific features of movement control while setting the global level of cerebellar activity through inhibition via rate coding mechanisms.

Impact of selective reporting of antibiotic susceptibility test results in urinary tract infections in the outpatient setting: a protocol for a pragmatic, prospective quasi-experimental trial.

INTRODUCTION: Antibiotic resistance is a serious and increasing worldwide threat to global public health. One of antibiotic stewardship programmes' objectives are to reduce inappropriate broad-spectrum antibiotics' prescription. Selective reporting of antibiotic susceptibility test (AST) results, which consists of reporting to prescribers only few (n=5-6) antibiotics, preferring first-line and narrow-spectrum agents, is one possible strategy advised in recommendations. However, selective reporting of AST has never been evaluated using an experimental design. METHODS AND ANALYSIS: This study is a pragmatic, prospective, multicentre, controlled (selective reporting vs usual complete reporting of AST), before-after (year 2019 vs 2017) study. Selective reporting of AST is scheduled to be implemented from September 2018 in the ATOUTBIO group of 21 laboratories for all Escherichia coli identified in urine cultures in adult outpatients, and to be compared with the usual complete AST performed in the EVOLAB group of 20 laboratories. The main objective is to assess the impact of selective reporting of AST for E. coli-positive urine cultures in the outpatient setting on the prescription of broad-spectrum antibiotics frequently used for urinary tract infections (amoxicillin-clavulanate, third-generation cephalosporins and fluoroquinolones). The primary end point is the after (2019)-before (2017) difference in prescription rates for the previously mentioned antibiotics/classes that will be compared between the two laboratory groups, using linear regression models. Secondary objectives are to evaluate the feasibility of selective reporting of AST implementation by French laboratories and their acceptability by organising focus groups and individual semi-structured interviews with general practitioners and laboratory professionals. ETHICS AND DISSEMINATION: This protocol was approved by French national ethics committees (Comité d'expertise pour les recherches, les études et les évaluations dans le domaine de la santé (TPS 29064) and Commission Nationale de l'Informatique et des Libertés (Décision DR-2018-141)). Findings of this study will be widely disseminated through conference presentations, reports, factsheets and academic publications and generalisation will be further discussed. TRIAL REGISTRATION NUMBER: NTC03612297.

Paroxysmal Nocturnal Hemoglobinuria (Pnh): Brain Mri Ischemic Lesions In Neurologically Asymtomatic Patients.

This study investigated for the first time brain ischemic involvement in 19 consecutive neurologically asymptomatic PNH patients by non-enhanced cerebral MRI, and by intracranial arterial and venous angio-MRI. Eleven cases (58%, 7 aged <65) showed pathological findings: 9 white matter (WM) abnormalities related to chronic ischemic small vessel disease, 2 a focal abnormality >5 mm, and 5 cases a score >4 by the age-related white matter changes (ARWMC) scale. Compared with age and sex-matched controls (1:2 ratio), patients showed an increased frequency of periventricular WM vascular degeneration (32% versus 5.2%, p = 0.04) and of severe lesions (ARWMC scale score >4) (26% versus 2.6%, p = 0.05), and a higher overall ARWMC scale score (3.5 ± 1.07 versus 2.0 ± 0.8, mean ± SD, p < 0.0001). Notably, vascular abnormalities suspected for prior partial venous thrombosis, were observed in PNH cases only. MRI lesions were not related to blood counts, hemolytic markers, clone size, disease duration, and therapy with eculizumab. Neurological examination was unremarkable in all patients but one (Parkinson disease). Psychiatric assessment revealed a case of generalized anxiety disorder, 1 bipolar disorder type 2, and 1 adjustment disorder. In conclusion, brain MRI may be useful at diagnosis and during the course of the disease to explore subclinical neurological involvement.

A simple model of HIV epidemic in Italy: The role of the antiretroviral treatment.

In the present paper we propose a simple time-varying ODE model to describe the evolution of HIV epidemic in Italy. The model considers a single population of susceptibles, without distinction of high-risk groups within the general population, and accounts for the presence of immigration and emigration, modelling their effects on both the general demography and the dynamics of the infected subpopulations. To represent the intra-host disease progression, the untreated infected population is distributed over four compartments in cascade according to the CD4 counts. A further compartment is added to represent infected people under antiretroviral therapy. The per capita exit rate from treatment, due to voluntary interruption or failure of therapy, is assumed variable with time. The values of the model parameters not reported in the literature are assessed by fitting available epidemiological data over the decade 2003÷2012. Predictions until year 2025 are computed, enlightening the impact on the public health of the early initiation of the antiretroviral therapy. The benefits of this change in the treatment eligibility consist in reducing the HIV incidence rate, the rate of new AIDS cases, and the rate of death from AIDS. Analytical results about properties of the model in its time-invariant form are provided, in particular the global stability of the equilibrium points is established either in the absence and in the presence of infected among immigrants.

Primary HIV infection in patients with acute hepatitis B: a report of two cases.

We describe two patients admitted to our institution with a diagnosis of sexually acquired acute hepatitis B who also had underlying hyper acute HIV infection. Both individuals reported high rates of condomless sex. Antiviral therapy active against HBV and HIV was started within days after diagnosis. Treatment was well tolerated and led to a rapid control of both infections and hepatitis B surface antibody seroconversion. The efficacy and safety of contemporary antiretroviral drug combinations suggest that treatment of acute HIV infection is feasible in patients with acute hepatitis B.

Short article: Retreatment of chronic hepatitis C virus infection after unsuccessful therapy with all-oral direct-acting antiviral regimens: a real-life experience.

OBJECTIVE: Few real-life data are available on the retreatment of patients who failed direct-acting antiviral (DAA)-regimens. We reported the outcome of retreatment with approved DAA regimens in a real-life cohort of patients who previously failed an all-oral DAAs combination and we analyzed the association with resistance substitutions (RASs) performed at the time of virological failure. AIM AND METHODS: Next-generation sequencing of the NS3, NS5A, and NS5B regions was performed by Illumina deep sequencing. The sequence reads were analyzed by an in-house pipeline. RESULTS: Of the 16/759 (2%) patients who failed to achieve a sustained virological response at 12 weeks to all-oral DAAs from December 2014 to January 2016, 10 were retreated with licensed DAAs regimens. In all the patients, retreatment was followed by sustained virological response at 12 weeks. Baseline NS3-RASs before retreatment were observed in two patients who failed a sofosbuvir/simeprevir regimen: D168V RAS was detected in a genotype-4 patient, whereas the complex RAS-pattern Q80K, I170V, R155K, D168E was observed in a genotype-1a patient. Only one of the two patients who previously failed ombitasvir, paritaprevir/ritonavir, and dasabuvir underwent RAS analysis at relapse and showed baseline NS5A RAS (M28V) before retreatment. CONCLUSION: These real-life findings indicated a high efficacy of sofosbuvir+NS5A-inihbitors in retreating NS3-experienced patients and also NS5A-experienced patients by using a 24-week course ribavirin-containing regimen. The relevance of hepatitis C virus resistance testing before retreatment remains to be better defined to guide the choice of the new regimen before retreatment in DAA-experienced patients.

Successful treatment of sexually acquired acute HCV reinfection with ledipasvir/sofosbuvir in a HIV-infected patient.

Here we describe the case of a HIV-positive patient with acute hepatitis C virus reinfection, who was successfully treated with an interferon-free regimen of ledipasvir/sofosbuvir.