Divergent landscapes of A-to-I editing in postmortem and living human brain.

Adenosine-to-inosine (A-to-I) editing is a prevalent post-transcriptional RNA modification within the brain. Yet, most research has relied on postmortem samples, assuming it is an accurate representation of RNA biology in the living brain. We challenge this assumption by comparing A-to-I editing between postmortem and living prefrontal cortical tissues. Major differences were found, with over 70,000 A-to-I sites showing higher editing levels in postmortem tissues. Increased A-to-I editing in postmortem tissues is linked to higher ADAR1 and ADARB1 expression, is more pronounced in non-neuronal cells, and indicative of postmortem activation of inflammation and hypoxia. Higher A-to-I editing in living tissues marks sites that are evolutionarily preserved, synaptic, developmentally timed, and disrupted in neurological conditions. Common genetic variants were also found to differentially affect A-to-I editing levels in living versus postmortem tissues. Collectively, these discoveries illuminate the nuanced functions and intricate regulatory mechanisms of RNA editing within the human brain.

Profiling tofersen as a treatment of superoxide dismutase 1 amyotrophic lateral sclerosis.

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a rapidly progressive motor neuron disorder with a fatal outcome 3-5 years after disease onset due to respiratory complications. Superoxide dismutase 1 (SOD1) mutations are found in about 2% of all patients. Tofersen is a novel oligonucleotide antisense drug specifically developed to treat SOD1-ALS patients. AREAS COVERED: Our review covers and discusses tofersen pharmacological properties and its phase I/II and III clinical trials results. Other available drugs and their limitations are also addressed. EXPERT OPINION: VALOR study failed to meet the primary endpoint (change in the revised Amyotrophic Lateral Sclerosis Functional Rating Scale score from baseline to week 28, tofersen arm vs. placebo), but a significant reduction in plasma neurofilament light chain (NfL) levels was observed in tofersen arm (60% vs. 20%). PrefALS study has proposed plasma NfL has a potential biomarker for presymptomatic treatment, since it increases 6-12 months before phenoconversion. There is probably a delay between plasma NfL reduction and the clinical benefit. ATLAS study will allow more insights regarding tofersen clinical efficacy in disease progression rate, survival, and even disease onset delay in presymptomatic SOD1 carriers.

The role of monitoring skills in mediating the association between parent's hazardous alcohol consumption and adolescents' drinking.

BACKGROUND: This study aimed to investigate whether parental monitoring skills mediate the effect of hazardous parental alcohol consumption on adolescents' lifetime alcohol use. METHODS: This three wave longitudinal study was conducted with 884 families (n = 1,768 participants) to evaluate the effectiveness of a family-based drug prevention program for adolescents and parents across 12 Brazilian cities. We used structural equation mediation modeling to analyze the effect of hazardous parental alcohol consumption at baseline on adolescents' lifetime alcohol use at 12-month follow-up, mediated by parental monitoring skills latent dimension at 6-month follow-up. RESULTS: We found a significant indirect effect of parents' hazardous alcohol use on adolescents' alcohol use through parental monitoring (OR:1.18, 95%CI:1.02;1.36). CONCLUSION: Our finding underscores the importance of comprehensive preventive family alcohol approaches targeting adolescent alcohol use, which should consider both parental drinking behavior and monitoring practices.

Peer review of the pesticide risk assessment of the active substance clove oil.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, Malta, for the pesticide active substance clove oil are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions for the amendment of approval were reached on the basis of the evaluation of the representative use of clove oil as a preharvest nematicide on tomatoes and cucumbers (permanent greenhouse use). The representative use evaluated for the renewal of approval of clove oil was as post-harvest fungicide and bactericide on apples, pears and peaches (indoor uses). The reliable endpoints appropriate for use in regulatory risk assessment are presented. Endpoints not relevant to the scope of the proposed amendment of approval conditions will be addressed in the context of the renewal of approval procedure of clove oil running in parallel (AIR IV, EFSA Q-2016-00809). Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Anti-TIF1γ-Dermatomyositis and Sjögren's Syndrome As the Inaugural Presentation for Rectal Cancer.

Dermatomyositis (DM) is an inflammatory myopathy often paraneoplastic in nature. Patients have characteristic cutaneous findings and possible muscle involvement. In the latter, muscle enzymes are elevated, and the electromyogram shows varied changes. Muscle or skin biopsy and myositis-specific antibodies confirm the diagnosis. Here, we report the case of an 86-year-old woman with cutaneous lesions, proximal weakness, and sicca symptoms. Muscle enzymes and electromyogram were normal. Antinuclear antibodies were elevated, and anti-TIF1γ and anti-Ro52 antibodies were positive. Muscle biopsy was compatible with the diagnosis of DM, and salivary gland biopsy confirmed Sjögren's syndrome. Malignancy investigation identified a rectal cancer, which was resected. This case illustrates a rare form of cancer presentation - anti-TIF1γ DM with normal muscle enzymes and electromyogram and concomitant secondary Sjögren's syndrome. Malignancy screening and multidisciplinary management were crucial to a successful approach.

Preliminary hazard assessment of a new nature-inspired antifouling (NIAF) agent.

A recently synthesized aminated 3,4-dioxygenated xanthone (Xantifoul2) was found to have promising antifouling (AF) effects against the settlement of the macrofouler Mytilus galloprovincialis larvae. Preliminary assessment indicated that Xantifoul2 has reduced ecotoxicological impacts: e.g., being non-toxic to the marine crustacea Artemia salina (<10 % mortality at 50 µM) and showing low bioconcentration factor in marine organisms. In order to meet the EU Biocidal Product Regulation, a preliminary hazard assessment of this new nature-inspired antifouling (NIAF) agent was conducted in this work. Xantifoul2 did not affect the swimming ability of the planktonic crustacean Daphnia magna, the growth of the diatom Phaeodactylum tricornutum, and the cellular respiration of luminescent Gram-negative bacteria Vibrio fischeri, supporting the low toxicity towards several non-target marine species. Regarding human cytotoxicity, Xantifoul2 did not affect the cell viability of retinal human cells (hTERT-RPE-1) and lipidomic studies revealed depletion of lipids involved in cell death, membrane modeling, lipid storage, and oxidative stress only at a high concentration (10 µM). Accelerated degradation studies in water were conducted under simulated sunlight to allow the understanding of putative transformation products (TPs) that could be generated in the aquatic ecosystems. Both Xantifoul2 and photolytic-treated Xantifoul2 in the aqueous matrix were therefore evaluated on several nuclear receptors (NRs). The results of this preliminary hazard assessment of Xantifoul2, combined with the high degradation rates in water, provide strong evidence of the safety of this AF agent under the evaluated conditions, and provide the support for future validation studies before this compound can be introduced in the market.

Diaphragm weakness in late-onset Pompe disease: A complex interplay between lower motor neuron and muscle fibre degeneration.

BACKGROUND: Late-onset Pompe disease (LOPD) patients may still need ventilation support at some point of their disease course, despite regular recombinant human alglucosidase alfa treatment. This suggest that other pathophysiological mechanisms than muscle fibre lesion can contribute to the respiratory failure process. We investigate through neurophysiology whether spinal phrenic motor neuron dysfunction could contribute to diaphragm weakness in LOPD patients. MATERIAL AND METHODS: A group of symptomatic LOPD patients were prospectively studied in our centre from January 2022 to April 2023. We collected both demographic and clinical data, as well as neurophysiological parameters. Phrenic nerve conduction studies and needle EMG sampling of the diaphragm were perfomed. RESULTS: Eight treated LOPD patients (3 males, 37.5%) were investigated. Three patients (37.5%) with no respiratory involvement had normal phrenic nerve motor responses [median phrenic compound muscle action potential (CMAP) amplitude of 0.49 mV; 1st-3rd interquartile range (IQR), 0.48-0.65]. Those with respiratory failure (under nocturnal non-invasive ventilation) had abnormal phrenic nerve motor responses (median phrenic CMAP amplitude of 0 mV; 1st-3rd IQR, 0-0.15), and were then investigated with EMG. Diaphragm needle EMG revealed both myopathic and neurogenic changes in 3 (60%) and myopathic potentials in 1 patient. In the last one, no motor unit potentials could be recruited. CONCLUSIONS: Our study provide new insights regarding respiratory mechanisms in LOPD, suggesting a contribution of spinal phrenic motor neuron dysfunction for diaphragm weakness. If confirmed in further studies, our results recommend the need of new drugs crossing the blood-brain barrier.

Nusinersen in adults with type 3 spinal muscular atrophy: long-term outcomes on motor and respiratory function.

INTRODUCTION: Nusinersen was approved for 5q spinal muscular atrophy (SMA), irrespective of age, SMA type or functional status. Nonetheless, long-term data on adults with milder phenotypes are scarce. We aimed to characterize evolution on motor and respiratory function in our cohort of adults with type 3 SMA. METHODS: We conducted a longitudinal retrospective single-center study, including adults (≥18 years) with type 3 SMA under nusinersen for > 22 months. We reported on motor scores and spirometry parameters. RESULTS: Ten patients were included, with a median follow-up of 34 months (range = 22-46). Four patients (40%) were walkers. None used non-invasive ventilation. In Revised Upper Limb Module (RULM) and Expanded Hammersmith Functional Motor Scale (HFMSE), difference of medians increased at 6, 22 and 46 months comparing to baseline (-0.5 vs. + 1.5 vs. + 2.5 in RULM; + 4.0 vs. + 7.5 vs. + 6.0 in HFMSE). Two (50%) walkers presented a clinically meaningful improvement in 6-min walk distance. We did not report any clinically meaningful decrement in motor scores. Spirometry parameters showed an increasing difference of medians in maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) (-3 vs. + 13.4 vs. + 28.7 percentage points of predicted value for MIP; + 11.8 vs. + 13.1 vs. 13.3 percentage points of predicted value for MEP). DISCUSSION: Our cohort supports a sustained benefit of nusinersen in adults with type 3 SMA, in motor and respiratory function. Multicentric studies are still warranted.

Upper motor neuron signs in primary lateral sclerosis and hereditary spastic paraplegia.

INTRODUCTION/AIMS: The frequency and distribution of upper motor neuron (UMN) signs in primary lateral sclerosis (PLS) are unknown. We aimed to study the spectrum of UMN signs in PLS and compare it with hereditary spastic paraplegia (HSP). METHODS: We retrospectively analyzed the frequency of different UMN signs, including hyperreflexia (limbs and jaw), limb and tongue spasticity, Babinski, and Hoffman signs, in PLS patients at first observation and compared this respect to onset region and symptom duration. We also compared PLS versus HSP patients. RESULTS: We included 34 PLS and 20 HSP patients, with a median symptom duration at first visit of 3.0 (interquartile range, IQR = 4.0) and 19.0 (IQR = 22.0) years, respectively. In PLS patients, hyperreflexia of upper (UL) (88.2%) and lower (LL) (91.2%) limbs, and LL spasticity (79.4%) were the most common findings. Spasticity of LL was significantly (p = .012) more frequent in LL-spinal onset subgroup, tongue spasticity in bulbar-onset subgroup (p = .021), and Hoffman sign in UL-spinal onset subgroup (p = .024). The PLS subgroup with shorter disease duration had a higher frequency of abnormal jaw jerk reflex (p = .037). Compared with HSP, PLS patients had a higher frequency of UL hyperreflexia (88.2% vs. 42.1%, p < .001) and UL spasticity (44.1% vs. 0.0%, p < .001). Asymmetric distribution of UMN signs was present in PLS and not in HSP. DISCUSSION: In PLS, UL UMN signs are nearly always present and UMN sign distribution appears to be associated with onset region. At first observation, bulbar involvement, asymmetrical distribution of UMN signs and UL spasticity may indicate PLS versus HSP.

Experimental data from the development of Lymnaea stagnalis embryo test for chemicals hazard assessment.

This study aimed to contribute to the development of an embryo-test using the gastropod Lymnaea stagnalis, identified by the Organization for Economic Co-operation and Development (OECD) as a potential invertebrate test animal model. Together with the Potamopyrgus antipodarum, were the first mollusc models to be included in the organization testing guidelines. The focus was on validating an embryo toxicity test to cover the sensitive embryogenesis phase and on obtaining testing information on all of the model life cycle stages, contributing to close an identified gap within this context. Adhering to OECD guidelines, namely the L. stagnalis reproductive test, the study examined mortality rates, abnormality rates, development, growth, hatching rates, hearth rates, and pre-testing media suitability, during the embryogenesis, and the obtained dataset made available for further studies. Cadmium was chosen as the positive test compound due to its well-studied nature and the model's proven sensitivity to the compound, working as a reference compound for the test development. The data were collected in two 12-day assays under consistent conditions, each using 144 L. stagnalis embryos (<24 h old) from 6 egg masses (288 embryos total). Six 48-well microplates were utilized per assay, accommodating five different cadmium concentrations (32, 70, 155, 341, 750 µg/L) and a control group. Recorded parameters encompassed developmental stage, embryo position within the chorion, developmental abnormalities, hatchings, and mortality. Data analysis involved classifying embryos based on developmental stage and position, taking an exploratory approach to define the relevance of the different parameters in the compound hazard assessment during the embryogenesis. Measurements considered embryo area, perimeter, length, height, width, interocular distance, and heart rate. This dataset does not provide treated information but the raw data obtained during the proposed metodological development and toxicity testing process. The purpose of this article is to make the obtained raw data available, clearly defining the acquisition methodology to provide a comparison basis for future or existent works within this context.

Peer review of the pesticide risk assessment of the active substance quinolin-8-ol.

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Spain, and co-rapporteur Member State, the Netherlands, for the pesticide active substance quinolin-8-ol are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative use of quinolin-8-ol as a fungicide and bactericide against soil-borne pathogens in tomato cultivation in permanent greenhouses applied by drip irrigation. The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Acute Pyelonephritis and an Incidental Diagnosis.

Gastrointestinal stromal tumors (GISTs) arise from the gastrointestinal tract. In rare cases, extra-gastrointestinal stromal tumors (EGISTs) occur in the omentum, mesentery, et cetera. They are mostly asymptomatic or have unspecific symptoms. Risk stratification classification systems are based on tumor size, mitotic rate, location, and perforation. The gold standard for diagnosis is a computed tomography (CT) scan. Ultrasound/CT-guided percutaneous biopsy allows histopathology and immunochemistry results (most stain positive for CD117 (c-KIT), CD34, and/or DOG1). Mutational analysis (most are in proto-oncogene c-KIT and platelet-derived growth factor receptor A (PDGFRA)) determines appropriate therapy. Surgical resection is the gold standard of treatment, with adjuvant and neoadjuvant molecular-targeted therapies depending on recurrence risk and mutations. This report describes a rare case of GIST (omentum EGIST) with a rare presentation (acute pyelonephritis) in a 67-year-old woman. Abdominal examination showed tenderness and a positive Murphy sign on the left side. Blood analysis presented microcytic hypochromic anemia, aggravated renal function, leukocytosis, and increased C-reactive protein. Abdominal CT revealed a heterogeneous abdominal mass, and a CT-guided biopsy showed epithelioid cells positive for CD117 and DOG1, which is compatible with a GIST. The patient underwent surgery that determined the GIST's origin from the greater omentum. Histology revealed an epithelioid GIST with large dimensions and a high histologic grade. Genetic testing detected a variant in the PDGFRA gene. With a high risk of progression, the patient received a three-year course of imatinib.

On-Demand Bioactivation of Inert Materials With Plasma-Polymerized Nanoparticles.

Conventional gas plasma treatments are crucial for functionalizing materials in biomedical applications, but have limitations hindering their broader use. These methods require exposure to reactive media under vacuum conditions, rendering them unsuitable for substrates that demand aqueous environments, such as proteins and hydrogels. In addition, complex geometries are difficult to treat, necessitating extensive customization for each material and shape. To address these constraints, an innovative approach employing plasma polymer nanoparticles (PPN) as a versatile functionalization tool is proposed. PPN share similarities with traditional plasma polymer coatings (PPC) but offer unique advantages: compatibility with aqueous systems, the ability to modify complex geometries, and availability as off-the-shelf products. Robust immobilization of PPN on various substrates, including synthetic polymers, proteins, and complex hydrogel structures is demonstrated in this study. This results in substantial improvements in surface hydrophilicity. Materials functionalization with arginylglycylaspartic acid (RGD)-loaded PPN significantly enhances cell attachment, spreading, and substrate coverage on inert scaffolds compared to passive RGD coatings. Improved adhesion to complex geometries and subsequent differentiation following growth factor exposure is also demonstrated. This research introduces a novel substrate functionalization approach that mimics the outcomes of plasma coating technology but vastly expands its applicability, promising advancements in biomedical materials and devices.

Updated peer review of the pesticide risk assessment of the active substance dichlorprop-P and variant dichlorprop-P-2-ethylhexyl.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Ireland, and co-rapporteur Member State, Poland, for the pesticide active substance dichlorprop-P and the variant dichlorprop-P-2-ethylhexyl and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of dichlorprop-P as a herbicide on cereals, grassland and grass seed crops and of the variant dichlorprop-P-2-ethylhexyl as a plant growth regulator on citrus. MRLs were assessed in mandarin and lemon. The conclusions from 2018 were updated in 2024 following the request from the European Commission with regard to the endocrine-disrupting properties. The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Transient peripheral blood transcriptomic response to ketamine treatment in children with ADNP syndrome.

Activity-dependent neuroprotective protein (ADNP) syndrome is a rare neurodevelopmental disorder resulting in intellectual disability, developmental delay and autism spectrum disorder (ASD) and is due to mutations in the ADNP gene. Ketamine treatment has emerged as a promising therapeutic option for ADNP syndrome, showing safety and apparent behavioral improvements in a first open label study. However, the molecular perturbations induced by ketamine remain poorly understood. Here, we investigated the longitudinal effect of ketamine on the blood transcriptome of 10 individuals with ADNP syndrome. Transcriptomic profiling was performed before and at multiple time points after a single low-dose intravenous ketamine infusion (0.5mg/kg). We show that ketamine triggers immediate and profound gene expression alterations, with specific enrichment of monocyte-related expression patterns. These acute alterations encompass diverse signaling pathways and co-expression networks, implicating up-regulation of immune and inflammatory-related processes and down-regulation of RNA processing mechanisms and metabolism. Notably, these changes exhibit a transient nature, returning to baseline levels 24 hours to 1 week after treatment. These findings enhance our understanding of ketamine's molecular effects and lay the groundwork for further research elucidating its specific cellular and molecular targets. Moreover, they contribute to the development of therapeutic strategies for ADNP syndrome and potentially, ASD more broadly.

Programming temporal stiffness cues within extracellular matrix hydrogels for modelling cancer niches.

Extracellular matrix (ECM) stiffening is a common occurrence during the progression of many diseases, such as breast cancer. To accurately mimic the pathophysiological context of disease within 3D in vitro models, there is high demand for smart biomaterials which replicate the dynamic and temporal mechanical cues of diseased states. This study describes a preclinical disease model, using breast cancer as an example, which replicates the dynamic plasticity of the tumour microenvironment by incorporating temporal (3-week progression) biomechanical cues within a tissue-specific hydrogel microenvironment. The composite hydrogel formulation, integrating adipose-derived decellularised ECM (AdECM) and silk fibroin, was initially crosslinked using a visible light-mediated system, and then progressively stiffened through spontaneous secondary structure interactions inherent between the polymer chains (∼10-15 kPa increase, with a final stiffness of 25 kPa). When encapsulated and cultured in vitro, MCF-7 breast cancer cells initially formed numerous, large spheroids (>1000 µm2 in area), however, with progressive temporal stiffening, cells demonstrated growth arrest and underwent phenotypic changes resulting in intratumoral heterogeneity. Unlike widely-investigated static mechanical models, this stiffening hydrogel allowed for progressive phenotypic changes to be observed, and fostered the development of mature organoid-like spheroids, which mimicked both the organisation and acinar-structures of mature breast epithelium. The spheroids contained a central population of cells which expressed aggressive cellular programs, evidenced by increased fibronectin expression and reduction of E-cadherin. The phenotypic heterogeneity observed using this model is more reflective of physiological tumours, demonstrating the importance of establishing temporal cues within preclinical models in future work. Overall, the developed model demonstrated a novel strategy to uncouple ECM biomechanical properties from the cellular complexities of the disease microenvironment and offers the potential for wide applicability in other 3D in vitro disease models through addition of tissue-specific dECM materials.

Evaluation of confirmatory data following the Article 12 MRL review and modification of the existing maximum residue levels for aluminium phosphide and magnesium phosphide.

The applicant Detia Freyberg GmbH submitted to the competent national authority in Germany two requests to evaluate the confirmatory data that were identified for tree nuts, oilseeds, cereals and commodities of animal origin in the framework of the maximum residue level (MRL) review under Article 12 of Regulation (EC) No 396/2005 as not available and two requests in accordance with Article 6 of Regulation (EC) No 396/2005 to increase the existing MRL for the active substance aluminium phosphide in peanuts, barley, oat, rye, rice and wheat, roots of herbal infusions, cocoa beans and seed spices and for the active substance magnesium phosphide in oilseeds (except peanuts) and pistachios. The four applications were combined by EFSA under the current assessment. To address the data gaps, validation data for the method of analysis for enforcement of phosphide in high-oil content commodities and new residue trials were submitted. The data gaps on additional residue trials supporting authorisations on oilseeds and cereal grains, on clarifications regarding the discrepancies observed in the residue trial results for pistachios, and on data confirming the negligible occurrence of phosphane and its oxidation products in livestock products were considered addressed. The data gap on independent laboratory validation (ILV) and a confirmatory method for monitoring of phosphide in high-oil content commodities was considered not fully addressed. The information provided justified a lowering of the current tentative MRLs for the whole group of cereals (except rice and 'others'), an increase of the current tentative MRLs for pistachios, the whole group of oilseeds, rice and 'other' cereals, herbal infusions from roots, cocoa beans and seed spices, and a revision of the risk assessment performed for phosphane and its phosphide salts. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of AlP and Mg3P2 according to the reported agricultural practices is unlikely to present a risk to consumer health. Further risk management considerations are required.

Updated peer review of the pesticide risk assessment of the active substance pydiflumetofen.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, France, and co-rapporteur Member State, Austria, for the pesticide active substance pydiflumetofen and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative uses of pydiflumetofen as a fungicide field application on pome fruits, grapes, potato, fruiting vegetables, cucurbits and Brassica vegetables and updated following the request from Commission to consider additional information submitted and review the risk assessment. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Segmental motor neuron dysfunction in amyotrophic lateral sclerosis: Insights from H reflex paradigms.

INTRODUCTION/AIMS: In amyotrophic lateral sclerosis (ALS), the role of spinal interneurons in ALS is underrecognized. We aimed to investigate pre- and post-synaptic modulation of spinal motor neuron excitability by studying the H reflex, to understand spinal interneuron function in ALS. METHODS: We evaluated the soleus H reflex, and three different modulation paradigms, to study segmental spinal inhibitory mechanisms. Homonymous recurrent inhibition (H'RI ) was assessed using the paired H reflex technique. Presynaptic inhibition of Ia afferents (H'Pre ) was evaluated using D1 inhibition after stimulation of the common peroneal nerve. We also studied inhibition of the H reflex after cutaneous stimulation of the sural nerve (H'Pos ). RESULTS: Fifteen ALS patients (median age 57.0 years), with minimal signs of lower motor neuron involvement and good functional status, and a control group of 10 healthy people (median age 57.0 years) were studied. ALS patients showed reduced inhibition, compared to controls, in all paradigms (H'RI 0.35 vs. 0.11, p = .036; H'Pre 1.0 vs. 5.0, p = .001; H'Pos 0.0 vs. 2.5, p = .031). The clinical UMN score was a significant predictor of the amount of recurrent and presynaptic inhibition. DISCUSSION: Spinal inhibitory mechanisms are impaired in ALS. We argue that hyperreflexia could be associated with dysfunction of spinal inhibitory interneurons. In this case, an interneuronopathy could be deemed a major feature of ALS.