Heterozygous knockout of Synaptotagmin13 phenocopies ALS features and TP53 activation in human motor neurons.

Spinal motor neurons (MNs) represent a highly vulnerable cellular population, which is affected in fatal neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). In this study, we show that the heterozygous loss of SYT13 is sufficient to trigger a neurodegenerative phenotype resembling those observed in ALS and SMA. SYT13+/- hiPSC-derived MNs displayed a progressive manifestation of typical neurodegenerative hallmarks such as loss of synaptic contacts and accumulation of aberrant aggregates. Moreover, analysis of the SYT13+/- transcriptome revealed a significant impairment in biological mechanisms involved in motoneuron specification and spinal cord differentiation. This transcriptional portrait also strikingly correlated with ALS signatures, displaying a significant convergence toward the expression of pro-apoptotic and pro-inflammatory genes, which are controlled by the transcription factor TP53. Our data show for the first time that the heterozygous loss of a single member of the synaptotagmin family, SYT13, is sufficient to trigger a series of abnormal alterations leading to MN sufferance, thus revealing novel insights into the selective vulnerability of this cell population.

Integrative proteomics highlight presynaptic alterations and c-Jun misactivation as convergent pathomechanisms in ALS.

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease mainly affecting upper and lower motoneurons. Several functionally heterogeneous genes have been associated with the familial form of this disorder (fALS), depicting an extremely complex pathogenic landscape. This heterogeneity has limited the identification of an effective therapy, and this bleak prognosis will only improve with a greater understanding of convergent disease mechanisms. Recent evidence from human post-mortem material and diverse model systems has highlighted the synapse as a crucial structure actively involved in disease progression, suggesting that synaptic aberrations might represent a shared pathological feature across the ALS spectrum. To test this hypothesis, we performed the first comprehensive analysis of the synaptic proteome from post-mortem spinal cord and human iPSC-derived motoneurons carrying mutations in the major ALS genes. This integrated approach highlighted perturbations in the molecular machinery controlling vesicle release as a shared pathomechanism in ALS. Mechanistically, phosphoproteomic analysis linked the presynaptic vesicular phenotype to an accumulation of cytotoxic protein aggregates and to the pro-apoptotic activation of the transcription factor c-Jun, providing detailed insights into the shared pathobiochemistry in ALS. Notably, sub-chronic treatment of our iPSC-derived motoneurons with the fatty acid docosahexaenoic acid exerted a neuroprotective effect by efficiently rescuing the alterations revealed by our multidisciplinary approach. Together, this study provides strong evidence for the central and convergent role played by the synaptic microenvironment within the ALS spinal cord and highlights a potential therapeutic target that counteracts degeneration in a heterogeneous cohort of human motoneuron cultures.

Aging-Dependent Altered Transcriptional Programs Underlie Activity Impairments in Human C9orf72-Mutant Motor Neurons.

Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disease characterized by dysfunction and loss of upper and lower motor neurons (MN). Despite several studies identifying drastic alterations affecting synaptic composition and functionality in different experimental models, the specific contribution of impaired activity to the neurodegenerative processes observed in ALS-related MN remains controversial. In particular, contrasting lines of evidence have shown both hyper- as well as hypoexcitability as driving pathomechanisms characterizing this specific neuronal population. In this study, we combined high definition multielectrode array (HD-MEA) techniques with transcriptomic analysis to longitudinally monitor and untangle the activity-dependent alterations arising in human C9orf72-mutant MN. We found a time-dependent reduction of neuronal activity in ALSC9orf72 cultures occurring as synaptic contacts undergo maturation and matched by a significant loss of mutant MN upon aging. Notably, ALS-related neurons displayed reduced network synchronicity most pronounced at later stages of culture, suggesting synaptic imbalance. In concordance with the HD-MEA data, transcriptomic analysis revealed an early up-regulation of synaptic terms in ALSC9orf72 MN, whose expression was decreased in aged cultures. In addition, treatment of older mutant cells with Apamin, a K+ channel blocker previously shown to be neuroprotective in ALS, rescued the time-dependent loss of firing properties observed in ALSC9orf72 MN as well as the expression of maturity-related synaptic genes. All in all, this study broadens the understanding of how impaired synaptic activity contributes to MN degeneration in ALS by correlating electrophysiological alterations to aging-dependent transcriptional programs.

Physeal sparing distal radio-ulnar joint ligament reconstruction in children.

Distal radio-ulnar joint (DRUJ) injuries are under-reported in the paediatric population. No single study has discussed methods of DRUJ reconstruction in immature patients with chronic instability. We present a physeal sparing ligamentoplasty for chronic DRUJ instability and describe the outcomes in two patients. Two consecutive children with chronic DRUJ instability were treated using physeal sparing ligamentoplasy. After the failure of triangular fibrocartilage complex repair, reconstruction was done using palmaris longus tendon graft that was tunnelled through the distal radius epiphysis and wrapped subperiosteally around the ulnar neck. Graft was tied in a neutral forearm position. DRUJ stability was achieved in both patients. Grip strength averaged 90% of the healthy side. Prono-supination range of motion (ROM) averaged 88 and 86%, respectively, of the healthy side, without intraoperative nor postoperative complications. Our novel technique was effective in the regain of DRUJ stability with minor effect on the prono-supination ROM. Further studies are planned to experiment the biomechanical effectiveness of our technique. Level of evidence: Therapeutic IV.

Sonography-Guided Peripheral Nerve Blocks for Hand Surgery.

Short procedures constitute a large proportion of hand surgeries. Most of them are done as 1-day surgery. Regional anesthesia is considered the best option for these operations. Compared with general anesthesia, regional anesthesia improves early outcome after wrist and hand surgery. Distal nerve blocks have the benefits of lying away from critical structures and the preservation of proximal muscle function of the upper limb. Thus, this type of nerve block is ideal for short procedures where patients can tolerate a tourniquet.

Synaptic disruption and CREB-regulated transcription are restored by K+ channel blockers in ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, which is still missing effective therapeutic strategies. Although manipulation of neuronal excitability has been tested in murine and human ALS models, it is still under debate whether neuronal activity might represent a valid target for efficient therapies. In this study, we exploited a combination of transcriptomics, proteomics, optogenetics and pharmacological approaches to investigate the activity-related pathological features of iPSC-derived C9orf72-mutant motoneurons (MN). We found that human ALSC9orf72 MN are characterized by accumulation of aberrant aggresomes, reduced expression of synaptic genes, loss of synaptic contacts and a dynamic "malactivation" of the transcription factor CREB. A similar phenotype was also found in TBK1-mutant MN and upon overexpression of poly(GA) aggregates in primary neurons, indicating a strong convergence of pathological phenotypes on synaptic dysregulation. Notably, these alterations, along with neuronal survival, could be rescued by treating ALS-related neurons with the K+ channel blockers Apamin and XE991, which, respectively, target the SK and the Kv7 channels. Thus, our study shows that restoring the activity-dependent transcriptional programme and synaptic composition exerts a neuroprotective effect on ALS disease progression.

Thumb metacarpophalangeal joint palmar plate chronic avulsion in children: diagnosis and treatment.

INTRODUCTION: Thumb metacarpophalangeal joint instability can have a considerable functional impairment. Acute injuries are usually overlooked in children due to the high pain threshold and the presence of ligamentous laxity. Chronicity of the injury results in failure of conservative treatment. Literature is poor in defining such injuries. The purpose of our study is to determine the clinical and radiological tools for the diagnosis of metacarpophalangeal joint instability and we propose a simple surgical technique for their management. METHODS: From 2015 till 2019, we present a case series of four patients with chronic post-traumatic thumb metacarpophalangeal joint instability. Patients were assessed for palmar plate avulsion clinically and radiologically using plain X-ray and sonography. Surgical repair through a palmar approach with direct repair of the palmar plate was done in all patients. Patient demographics, complications, and clinical outcomes were recorded. RESULTS: Mean follow-up was 22.5 months. At the latest follow-up the metacarpophalangeal joint was stable in all patients. They were all pain free except one patient suffered from temporary pain at the dorsum of the metacarpal due to prominence of the suture anchor, which disappeared at 1-year follow-up. They had improvement in pinch strength. Full range of motion was obtained and all the patients have returned to full activity without limitations. CONCLUSION: Chronic post-traumatic thumb metacarpophalangeal joint instability results in functional impairment. Clinical suspicion and sonographic assessment can verify the diagnosis. Surgical repair with transosseous sutures or anchors yields satisfactory results in the paediatric age group with the preservation of normal range of motion.

Cadaveric evaluation of the feasibility of glenohumeral joint denervation.

PURPOSE: To assess the feasibility of total shoulder denervation through two proposed incisions. METHODS: Total shoulder denervation was performed through an extended delta-pectoral approach and a transverse dorsal approach at the spine of the scapula. The study involved six cadavers. Course and number of articular branches from the lateral pectoral, axillary and supra-scapular nerve were documented. RESULTS: All shoulder joint articular branches were accessible through the proposed anterior and posterior approaches. The articular branch of the lateral pectoral nerve and supra scapular nerve were present in all the specimen. Axillary nerve articular branches were variable in number but when present anteriorly were proximal to the deltoid muscular branches and posteriorly proximal to the muscular branches to the teres minor. CONCLUSION: Total glenohumeral denervation was feasible through our proposed anterior and posterior approaches. Enhanced knowledge of articular nerve branches could provide interventional targets for joint and ligament pain, with low risk of muscle weakness.

Reliability of propeller flaps in post-traumatic reconstruction of wrist and hand defects.

PURPOSE: This is a purely observational study with a literature comparison to assess the effectiveness of radial and ulnar arteries propeller perforator-based flaps in post-traumatic soft tissue reconstruction and identify the risk factors for complications. METHODS: Sixteen patients were involved with post-traumatic wrist and hand soft tissue defects not exceeding 5 × 20 cm. Defects were covered with propeller radial and ulnar arteries perforator-based flaps. Patient demographics, soft tissue defects, complications and clinical outcomes were recorded. Assessment of patients' satisfaction for donor site morbidity and aesthetic outcome of the flap were performed. RESULTS: Radial artery propeller perforator flap was performed in seven cases, and ulnar artery propeller perforator flap was done in nine cases. The size of the skin paddle ranged from 2.5 × 5 cm to 4.5 × 10.5 cm. Primary closure of the donor site was performed in all cases. One flap was lost, while superficial epidermolysis occurred in seven cases (45%). Edge necrosis ranging between 3 and 7 mm occurred in nine cases (60%). Patients' factors, mode of injury, associated injuries and interval between trauma and coverage were all correlated with complication incidence. The patients' satisfaction for donor site morbidity was very good and good in 80% of patients, while satisfaction for aesthetic outcome of the flap was very good and good in only 40%. CONCLUSION: Radial and ulnar arteries have reliable perforators for flap elevation, which produce reliable outcome for small- and medium-sized soft tissue reconstruction. Effectiveness decreases in post-traumatic reconstructions. Complications are more frequent in crushing injuries especially if associated with bony fractures. Most complications in trauma cases were attributed to venous congestion, for which supercharging with a vein if accessible to the surgeon is recommended.

FUS-mediated regulation of acetylcholine receptor transcription at neuromuscular junctions is compromised in amyotrophic lateral sclerosis.

Neuromuscular junction (NMJ) disruption is an early pathogenic event in amyotrophic lateral sclerosis (ALS). Yet, direct links between NMJ pathways and ALS-associated genes such as FUS, whose heterozygous mutations cause aggressive forms of ALS, remain elusive. In a knock-in Fus-ALS mouse model, we identified postsynaptic NMJ defects in newborn homozygous mutants that were attributable to mutant FUS toxicity in skeletal muscle. Adult heterozygous knock-in mice displayed smaller neuromuscular endplates that denervated before motor neuron loss, which is consistent with 'dying-back' neuronopathy. FUS was enriched in subsynaptic myonuclei, and this innervation-dependent enrichment was distorted in FUS-ALS. Mechanistically, FUS collaborates with the ETS transcription factor ERM to stimulate transcription of acetylcholine receptor genes. Co-cultures of induced pluripotent stem cell-derived motor neurons and myotubes from patients with FUS-ALS revealed endplate maturation defects due to intrinsic FUS toxicity in both motor neurons and myotubes. Thus, FUS regulates acetylcholine receptor gene expression in subsynaptic myonuclei, and muscle-intrinsic toxicity of ALS mutant FUS may contribute to dying-back motor neuronopathy.