25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Paraneoplastic edematous dermatomyositis: A rare syndrome observed in a case of small cell lung cancer

Dermatomyositis with subcutaneous edema is a rare process with few reported cases. We report a 63-year-old with lung cancer who presented with an erythematous skin rash and was found to have biopsyproven dermatomyositis. Her course was complicated by generalized edema, myalgias, muscle weakness, dysphagia, and laryngeal edema. The edema was severe and caused respiratory distress requiring intubation. The patient underwent therapy with high-dose glucocorticoids and intravenous immunoglobulin but failed treatment. Altogether, she presented as an extreme case and rare variant of dermatomyositis, known as edematous dermatomyositis. Diagnostic and treatment guidelines do not account for this variant and literature pertaining to edematous dermatomyositis is sparse. Moreover, this disease was a paraneoplastic manifestation of her small cell lung cancer, which is rarely observed. There are no cases reporting edematous dermatomyositis as a paraneoplastic manifestation of small cell lung cancer, and we highlight the high rate of morbidity and mortality in such patients

Gene transfer in skeletal and cardiac muscle using recombinant adeno-associated virus

Adeno-associated virus (AAV) is a DNA virus with a small ( approximately 4.7 kb) single-stranded genome. It is a naturally replication-defective parvovirus of the dependovirus group. Recombinant AAV (rAAV), for use as a gene transfer vector, is created by replacing the viral rep and cap genes with the transgene of interest along with promoter and polyadenylation sequences. Only the viral inverted terminal repeats (ITRs) are required in cis for replication and packaging during production. The ITRs are also necessary and sufficient for vector genome processing and persistence during transduction. The tissue tropism of the rAAV vector is determined by the AAV capsid. In this unit we will discuss several methods to deliver rAAV in order to transduce cardiac and/or skeletal muscle, including intravenous delivery, intramuscular delivery, isolated limb infusion, intrapericardial injection in neonatal mice, and left ventricular wall injection in adult rats