Abbreviations used: CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione; D-APV, D-2-amino-5-phosphonovalerate; DIV, days in vitro; eGFP, enhanced green fluorescent protein; GFAP, glial fibrillary acidic protein; MEA, multielectrode array; NR1, NMDA receptor subunit 1; PI, propidium iodide; PSD-95, post-synaptic density protein 95 kDa; TEM, transmission electron microscopy; VGAT, vesicular GABA transporter; VGLUT1, vesicular glutamate transporter. AbstractIn this paper, we report the characterization of 'Hi-Spot' cultures formed by the re-aggregation of dissociated postnatal CNS tissue grown at an air-liquid interface. This produces a self-organised, dense, organotypic cellular network. Western blot, immunohistochemical, viral transfection and electron microscopy analyses reveal neuronal and glial populations, and the development of a synaptic network. Multi-electrode array recordings show synaptically driven network activity that develops through time from single unit spiking activity to global network bursting events. This activity is blocked by tetanus toxin and modified by antagonists of glutamatergic and GABAergic receptors suggesting tonic activity of excitatory and inhibitory synaptic signaling. The tissue-like properties of these cultures has been further demonstrated by their relative insensitivity to glutamate toxicity. Exposure to millimolar concentrations of glutamate for hours is necessary to produce significant excitotoxic neuronal death, as in vivo. We conclude that 'Hi-Spots' are biological analogues of CNS tissue at a level of complexity that allows for detailed functional analyses of emergent neuronal network properties.

A generic model of a rowing craft is presented and used to identify the mechanics of the rowing stroke that give rise to variations in the speed of a rowing shell, together with the causes and locations of maximum and minimum shell speeds through the stroke. The model is implemented computationally in a velocity prediction program which uses readily available measured data for the input and simulates the motion of the athlete using a seven-body-segment model. The rowing model is derived to avoid limitations that arise from the quasi-steady application of steady state data to the unsteady flow around the oar blades and includes hydrodynamic and aerodynamic resistance models. Propulsive drive forces arise as a result of the difference between the gate and handle forces due to the lever action of the oar. The surge motion is dominated by the inertial forces arising as a result of the athlete's motion within the craft which are much larger in magnitude than the drive forces. The minimum surge speed occurs midway through the drive phase. Two distinct maxima in the surge speed occur: one at the end of the drive as the athlete comes to rest at the end of the stroke, and one during the recovery as the athlete's seat attains the maximum speed backwards relative to the craft. The relative magnitudes of these peaks are mainly determined by the ratio of the drive time to the recovery time.

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INTRODUCTION: Patients who suffer neurologic injury that require ventriculoperitoneal shunt(VPS) placement often also require gastrostomy procedures for feeding access and nutritional support. The timing of these procedures in relation to each other has been debated in the literature, largely steaming from a proposed risk of infection and displacement resulting in a need for revision related to the presence of a gastrostomy.METHODS: In an all-payor database, patients undergoing index gastrostomy procedures and VPS placement between 1/2010-10/2020 were identified. Patients were stratified as undergoing gastrostomy placement before, on the same day as, and following the placement of a shunt. The primary outcome of the study was rates of revision All outcomes were evaluated within 30-months following index-shunting. Patients were matched based upon logistic-regression models that evaluated the independent effects of patient and procedural factors on the primary-outcome.RESULTS: A total of 4,290-patients were identified as undergoing VPS and gastrostomy procedures. Following a 1:1:1-match procedure, 852-patient records were analyzed. Patients undergoing gastrostomy and VPS on the same day or gastrostomy procedures before VPS (Odds Ratio [OR] 0.55, 95% Confidence Interval [CI] 0.33-0.91 vs. OR 0.60, 95% CI 0.36-0.97, respectively) were observed to have significantly lower rates of revision at 30-months following index shunting when compared to those patients who underwent gastrostomy placement after VPS. No significant differences were noted in rates of infection, mechanical complications, g-tube infections, or shunt displacement between the three approaches.CONCLUSIONS: Patients undergoing shunting and gastrostomy tube placement procedures may benefit from undergoing the procedures at the same time as patients undergoing these procedures at the same time are at a decreased risk of repeat requirement for anesthesia reduced rates of VPS revision following observed in comparison to patients undergoing gastrostomy placement after VPS.

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