Waddling Gait: A complication of valproate therapy and a thought beyond vitamin D deficiency

Proximal muscle weakness is a common presentation in paediatric-orthopaedic clinics and is frequently paired with a vitamin D deficiency diagnosis. Recently, side effects of the extensive use of antiepileptic and antipsychotic drugs such as sodium valproate in childhood disorders are being documented. Sodium valproate causes a time-dependent, drug-induced proximal myopathy. We report a 13-year-old female patient who presented at the Orthopaedic Outpatient Department at Lady Hardinge Medical College, New Delhi, India, in 2019 with an abnormal gait. The patient was taking a combination therapy of sodium valproate, risperidone and trihexyphenidyl for absence seizures and a mood disorder. Following clinical investigations, the patient was diagnosed with proximal myopathy. As a result of elevated serum alkaline phosphatase and creatine kinase myocardial band levels, sodium valproate was replaced with ethosuximide and a carnitine supplementation was prescribed. The patient fully recovered and regained full mobility. Proximal myopathy had been incorrectly managed and assumed to be caused by a vitamin D deficiency.Keywords: Muscle Weakness; Carnitine; Myopathy; Valproic Acid; Vitamin D Deficiency; Gait; Case Report; India

Modality-Specific Axonal Regeneration: Toward Selective Regenerative Neural Interfaces

Regenerative peripheral nerve interfaces have been proposed as viable alternatives for the natural control of robotic prosthetic devices. However, sensory and motor axons at the neural interface are of mixed sub-modality types, which difficult the specific recording from motor axons and the eliciting of precise sensory modalities through selective stimulation. Here we evaluated the possibility of using type specific neurotrophins to preferentially entice the regeneration of defined axonal populations from transected peripheral nerves into separate compartments. Segregation of mixed sensory fibers from dorsal root ganglion neurons was evaluated in vitro by compartmentalized diffusion delivery of nerve growth factor (NGF) and neurotrophin-3 (NT-3), to preferentially entice the growth of TrkA+ nociceptive and TrkC+ proprioceptive subsets of sensory neurons, respectively. The average axon length in the NGF channel increased 2.5-fold compared to that in saline or NT-3, whereas the number of branches increased threefold in the NT-3 channels. These results were confirmed using a 3D “Y”-shaped in vitro assay showing that the arm containing NGF was able to entice a fivefold increase in axonal length of unbranched fibers. To address if such segregation can be enticed in vivo, a “Y”-shaped tubing was used to allow regeneration of the transected adult rat sciatic nerve into separate compartments filled with either NFG or NT-3. A significant increase in the number of CGRP+ pain fibers were attracted toward the sural nerve, while N-52+ large-diameter axons were observed in the tibial and NT-3 compartments. This study demonstrates the guided enrichment of sensory axons in specific regenerative chambers, and supports the notion that neurotrophic factors can be used to segregate sensory and perhaps motor axons in separate peripheral interfaces

High probability neurotransmitter release sites represent an energy efficient design

At most synapses, the probability of neurotransmitter release from an active zone (PAZ) is low, a design thought to confer many advantages. Yet, high PAZ can also be found at synapses. Speculating that high PAZ confers high energy efficiency, we examined energy efficiency at terminals of two Drosophila motor neurons (MNs) synapsing on the same muscle fiber, but with contrasting average PAZ. Through electrophysiological and ultrastructural measurements we calculated average PAZ for MNSNb/d-Is and MN6-Ib terminals (0.33±0.10 and 0.11±0.02 respectively). Using a miles-per-gallon analogy, we calculated efficiency as the number of glutamate molecules released for each ATP molecule that powers the release and recycling of glutamate and the removal of calcium (Ca2+) and sodium (Na+). Ca2+ and Na+ entry were calculated by microfluorimetry and morphological measurements respectively. Terminals with the highest PAZ release more glutamate but admit less Ca2+ and Na+, supporting the hypothesis that high PAZ confers greater energy efficiency than low PAZ (0.13±0.02 and 0.06±0.01 respectively). In an analytical treatment of parameters that influence efficiency we found that efficiency could be optimized in either terminal by increasing PAZ. Terminals with highest PAZ operate closest to this optimum but are less active and less able to sustain high release rates. Adopting an evolutionary biological perspective, we interpret the persistence of low PAZ release sites at more active terminals to be the result of selection pressures for sustainable neurotransmitter release dominating selection pressures for high energy efficiency

Discovery and functional prioritization of Parkinson's disease candidate genes from large-scale whole exome sequencing.

BACKGROUND: Whole-exome sequencing (WES) has been successful in identifying genes that cause familial Parkinson's disease (PD). However, until now this approach has not been deployed to study large cohorts of unrelated participants. To discover rare PD susceptibility variants, we performed WES in 1148 unrelated cases and 503 control participants. Candidate genes were subsequently validated for functions relevant to PD based on parallel RNA-interference (RNAi) screens in human cell culture and Drosophila and C. elegans models. RESULTS: Assuming autosomal recessive inheritance, we identify 27 genes that have homozygous or compound heterozygous loss-of-function variants in PD cases. Definitive replication and confirmation of these findings were hindered by potential heterogeneity and by the rarity of the implicated alleles. We therefore looked for potential genetic interactions with established PD mechanisms. Following RNAi-mediated knockdown, 15 of the genes modulated mitochondrial dynamics in human neuronal cultures and four candidates enhanced α-synuclein-induced neurodegeneration in Drosophila. Based on complementary analyses in independent human datasets, five functionally validated genes-GPATCH2L, UHRF1BP1L, PTPRH, ARSB, and VPS13C-also showed evidence consistent with genetic replication. CONCLUSIONS: By integrating human genetic and functional evidence, we identify several PD susceptibility gene candidates for further investigation. Our approach highlights a powerful experimental strategy with broad applicability for future studies of disorders with complex genetic etiologies

Breast cancer management pathways during the COVID-19 pandemic: outcomes from the UK ‘Alert Level 4’ phase of the B-MaP-C study

Abstract: Background: The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions. Methods: This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT)-guided treatment recommendations during the pandemic, designated ‘standard’ or ‘COVID-altered’, in the preoperative, operative and post-operative setting. Findings: Of 3776 patients (from 64 UK units) in the study, 2246 (59%) had ‘COVID-altered’ management. ‘Bridging’ endocrine therapy was used (n = 951) where theatre capacity was reduced. There was increasing access to COVID-19 low-risk theatres during the study period (59%). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2–9%) using ‘NHS Predict’. There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1%) tested positive for SARS-CoV-2 during their treatment journey. Conclusions: The majority of ‘COVID-altered’ management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic. However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown

Antimicrobial screening of various extracts of Aphanmixis polystachya stems bark

The dried stem bark of Aphanmixis polystachya (Melieceae) was extracted with alcoholic, hydroalcoholic and aqueous solvent for 36 hours in soxhlet apparatus and solvents from extracts was evaporated under vacuum. All three extracts were further fractionized in to the petroleum ether, ethyl acetate and n-butanol fractions and studied for in vitro antimicrobial activity by Agar cup method using different bacterial strains in nutrient agar media. For screening of antimicrobial activity, these extracts of dried stem bark of Aphanmixis polystachya was used at the dose of 500 mcg/cup against the kanamycin, which was used as standard antimicrobial agent at the dose of 30mcg/cup. The zone of inhibitions indicates that the extracts of dried stem bark of Aphanmixis polystachya showed significant antimicrobial activity as comparison to kanamycin.Keywords: Aphanmixis polystachya, Melieceae, Antimicrobial, Kanamycin

MAPRE2 mutations result in altered human cranial neural crest migration, underlying craniofacial malformations in CSC-KT syndrome

Circumferential skin creases (CSC-KT) is a rare polymalformative syndrome characterised by intellectual disability associated with skin creases on the limbs, and very characteristic craniofacial malformations. Previously, heterozygous and homozygous mutations in MAPRE2 were found to be causal for this disease. MAPRE2 encodes for a member of evolutionary conserved microtubule plus end tracking proteins, the end binding (EB) family. Unlike MAPRE1 and MAPRE3, MAPRE2 is not required for the persistent growth and stabilization of microtubules, but plays a role in other cellular processes such as mitotic progression and regulation of cell adhesion. The mutations identified in MAPRE2 all reside within the calponin homology domain, responsible to track and interact with the plus-end tip of growing microtubules, and previous data showed that altered dosage of MAPRE2 resulted in abnormal branchial arch patterning in zebrafish. In this study, we developed patient derived induced pluripotent stem cell lines for MAPRE2, together with isogenic controls, using CRISPR/Cas9 technology, and differentiated them towards neural crest cells with cranial identity. We show that changes in MAPRE2 lead to alterations in neural crest migration in vitro but also in vivo, following xenotransplantation of neural crest progenitors into developing chicken embryos. In addition, we provide evidence that changes in focal adhesion might underlie the altered cell motility of the MAPRE2 mutant cranial neural crest cells. Our data provide evidence that MAPRE2 is involved in cellular migration of cranial neural crest and offers critical insights into the mechanism underlying the craniofacial dysmorphisms and cleft palate present in CSC-KT patients. This adds the CSC-KT disorder to the growing list of neurocristopathies

The Redistribution of Drosophila Vesicular Monoamine Transporter Mutants from Synaptic Vesicles to Large Dense-Core Vesicles Impairs Amine-Dependent Behaviors

Monoamine neurotransmitters are stored in both synaptic vesicles (SVs), which are required for release at the synapse, and large dense-core vesicles (LDCVs), which mediate extrasynaptic release. The contributions of each type of vesicular release to specific behaviors are not known. To address this issue, we generated mutations in the C-terminal trafficking domain of the Drosophila vesicular monoamine transporter (DVMAT), which is required for the vesicular storage of monoamines in both SVs and LDCVs. Deletion of the terminal 23 aa (DVMAT-Δ3) reduced the rate of endocytosis and localization of DVMAT to SVs, but supported localization to LDCVs. An alanine substitution mutation in a tyrosine-based motif (DVMAT-Y600A) also reduced sorting to SVs and showed an endocytic deficit specific to aminergic nerve terminals. Redistribution of DVMAT-Y600A from SV to LDCV fractions was also enhanced in aminergic neurons. To determine how these changes might affect behavior, we expressed DVMAT-Δ3 and DVMAT-Y600A in a dVMAT null genetic background that lacks endogenous dVMAT activity. When expressed ubiquitously, DVMAT-Δ3 showed a specific deficit in female fertility, whereas DVMAT-Y600A rescued behavior similarly to DVMAT-wt. In contrast, when expressed more specifically in octopaminergic neurons, both DVMAT-Δ3 and DVMAT-Y600A failed to rescue female fertility, and DVMAT-Y600A showed deficits in larval locomotion. DVMAT-Y600A also showed more severe dominant effects than either DVMAT-wt or DVMAT-Δ3. We propose that these behavioral deficits result from the redistribution of DVMAT from SVs to LDCVs. By extension, our data suggest that the balance of amine release from SVs versus that from LDCVs is critical for the function of some aminergic circuits