SYNTHESIS, CHARACTERIZATION AND QUANTITATION OF REGIOISOMERIC IMPURITY IN NIMODIPINE BULK AND FORMULATION

Objective: The present research work was directed towards the synthesis characterization and quantitation of regioisomeric impurity of Nimodipine i.e. diethyl 1, 4-dihydro-2,6-dimethyl pyridine dicarboxylate in bulk and tablet formulation, by UV,IR,NMR and GC-MS techniques and a RP-HPLC method was developed as per ICH Q2B guidelines for quantitation of 1, 4-Dihydro-2, 6-Dimethyl-4-(p-nitro phenyl) pyridine-3,5 dicarboxylate (NI) from bulk and formulation. Methods: The synthesis of NI was carried out by Hantzch pyridine synthesis, by using p-nitrobenzaldehyde, ethylacetoacetate, in presence of ammonia and methanol as a catalyst. The percentage yield was found to be 89.29%. Recrystallization and purification of NI was done. The preliminary evaluation was done on laboratory scale via melting point, elemental analysis and TLC. Results: The melting point of impurity was found to be 156-1580C. The TLC of impurity was carried by using Chloroform: Methanol (9:1) and the Rf was found to be 0.79. The confirmation of structure of NI was carried out by using sophisticated techniques i.e., FT-IR, NMR (13C and 1H), GC-MS etc. The RP-HPLC method was developed to quantify the NI in Nimodipine bulk and formulation as per ICH Q2B guidelines. The method validation was done as per ICH guidelines. Conclusion: The validated optimized method was found to be linear, précised, robust, rugged and accurate. Finally NI was quantified from bulk Nimodipine and its marketed tablet formulation. It was concluded that the amount of NI, present in tablet was found to be 0.1% and in the bulk 0.067% respectively. Thus it was revealed that the NI was found to be within the limit laid down ICH guidelines (Not more than 0.1 %)

Expression of Developmentally Important Axon Guidance Cues in the Adult Optic Chiasm.

Funder: Wellcome TrustPURPOSE: Regeneration of optic nerve axons after injury can be facilitated by several approaches, but misguidance at the optic chiasm is often observed. We characterized guidance cues in the embryonic visual system and adult optic chiasm before and after optic nerve crush (ONC) injury to better understand barriers to optic nerve regeneration in adults. METHODS: Radial glial (RC2/BLBP/Slit1), developmental (Pax2) and extracellular markers (CSPG: H2B/CS-56) were assessed in C57BL/6J mice by immunohistochemistry. RC2, BLBP, Slit1, and CSPG are known inhibitory guidance cues while Pax2 is a permissive guidance cue. RESULTS: At embryonic day 15.5 (E.15.5), RC2 and BLBP were identified superior to, and extending through, the optic chiasm. The optic chiasm was BLBP-ve in adult uninjured mice but BLBP+ve in adult mice 10 days after ONC injury. The reverse was true for RC2. Both BLBP and RC2 were absent in adult mice 6 weeks post-ONC. Slit1 was present in the optic chiasm midline and optic tracts in embryonic samples but was absent in uninjured adult tissue. Slit1 was observed superior to and at the midline of the optic chiasm 10 days post-ONC but absent 6 weeks after injury. Pax2 was expressed at the junction between the optic nerve and optic chiasm in embryonic brain tissue. In embryonic sections, CS-56 was observed at the junction between the optic chiasm and optic tract, and immediately superior to the optic chiasm. Both 2H6 and CS-56 staining was absent in uninjured and ONC-injured adult brains. CONCLUSION: Differences in guidance cue expression during development, in adulthood and after injury may contribute to misguidance of regenerating RGC axons in the adult optic chiasm

Third-order motifs are sufficient to fully and uniquely characterize spatiotemporal neural network activity

Neuroscientific analyses balance between capturing the brain’s complexity and expressing that complexity in meaningful and understandable ways. Here we present a novel approach that fully characterizes neural network activity and does so by uniquely transforming raw signals into easily interpretable and biologically relevant metrics of network behavior. We first prove that third-order (triple) correlation describes network activity in its entirety using the triple correlation uniqueness theorem. Triple correlation quantifies the relationships among three events separated by spatial and temporal lags, which are triplet motifs. Classifying these motifs by their event sequencing leads to fourteen qualitatively distinct motif classes that embody well-studied network behaviors including synchrony, feedback, feedforward, convergence, and divergence. Within these motif classes, the summed triple correlations provide novel metrics of network behavior, as well as being inclusive of commonly used analyses. We demonstrate the power of this approach on a range of networks with increasingly obscured signals, from ideal noiseless simulations to noisy experimental data. This approach can be easily applied to any recording modality, so existing neural datasets are ripe for reanalysis. Triple correlation is an accessible signal processing tool with a solid theoretical foundation capable of revealing previously elusive information within recordings of neural networks

Publisher Correction: Whole-genome sequencing of a sporadic primary immunodeficiency cohort (Nature, (2020), 583, 7814, (90-95), 10.1038/s41586-020-2265-1)

An amendment to this paper has been published and can be accessed via a link at the top of the paper