Физико-механические свойства керамоматричных композитов ZrO[2]/нановолокна Al[2]O[3], полученных свободным спеканием

Differential isoform expression and phosphorylation of protein tau are believed to regulate the assembly and stabilization of microtubuli in fetal and adult neurons. To define the functions of tau in the developing and adult brain, we generated transgenic mice expressing the human tau-4R/2N (htau-4R) isoform on a murine tau null background, by a knockout/knockin approach (tau-KOKI). The main findings in these mice were the significant increases in hippocampal volume and neuronal number, which were sustained throughout adult life and paralleled by improved cognitive functioning. The increase in hippocampal size was found to be due to increased neurogenesis and neuronal survival. Proliferation and neuronal differentiation were further analyzed in primary hippocampal cultures from tau-KOKI mice, before and after htau-4R expression onset. In absence of tau, proliferation increased and both neurite and axonal outgrowth were reduced. Htau-4R expression suppressed proliferation, promoted neuronal differentiation, and restored neurite and axonal outgrowth. We suggest that the tau-4R isoform essentially contributes to hippocampal development by controlling proliferation and differentiation of neuronal precursors

Longterm stability and developmental changes in spontaneous network burst firing patterns in dissociated rat cerebral cortex cell cultures on multielectrode arrays

Spontaneous action potentials were recorded longitudinally for 4–7 weeks from dissociated rat occipital cortex cells cultured on planar multi-electrode plates, during their development from isolated neurons into synaptically connected neuronal networks. Activity typically consisted of generalized bursts lasting up to several seconds, separated by variable epochs of sporadic firing at some of the active sites. These network bursts displayed discharge patterns with age-dependent firing rate profiles, and durations significantly increasing in the 3rd week in vitro and decreasing after about 1 month in vitro, when they evolved into short events with prompt onsets. These findings indicate that after about a month in vitro these cultured neuronal networks have developed a degree of excitability that allows almost instantaneous triggering of generalized discharges. Individual neurons tend to fire in specific and persistent temporal relationships to one another within these network bursts, suggesting that network connectivity maintains a core topology during its development

Long Term Depression in the CA1 field is associated with a transient decrease in Pre-and Post-synaptic PKC substrate phosphorylation

Induction of homosynaptic long term depression (LTD) in the CA1 field of the hippocampus is thought to require activation of N-methyl-D-aspartate receptors, an elevation of postsynaptic Ca2+ levels, and a subsequent increase in phosphatase activity. To investigate the spatial and temporal changes in protein phosphatase activity following LTD induction, we determined the in situ phosphorylation state of a pre- (GAP-43/B-50) and postsynaptic (RC3) protein kinase C substrate during N-methyl-D-aspartate receptor-dependent LTD in the CA1 field of rat hippocampal slices. We show that LTD is associated with a transient (<30 min) and D-AP5-sensitive reduction in GAP-43/B-50 and RC3 phosphorylation and that LTD is prevented by the phosphatase inhibitors okadaic acid and cyclosporin A. Our data provide strong evidence for a transient increase in pre- and postsynaptic phosphatase activity during LTD. Since the in situ phosphorylation of the calmodulin-binding proteins GAP-43/B-50 and RC3 changes during both LTD and long term potentiation, these proteins may form part of the link between the Ca2+ signal and Ca2+/calmodulin-dependent processes implicated in long term potentiation and LTD

Dual compartment neurofluidic system for electrophysiological measurements in physically isolated neuronal cell cultures.

This work investigates an approach to record electrophysiological measurements of neuronal cell cultures in a dual compartment neurofluidic system. The two compartments are separated by 10-μm-wide and 3-μm-high microchannels and this provides a physical isolation of neurons allowing only neurites to grow between the compartments. We present long-term cell viability in closed compartment devices, neurite growth across the microchannels and a recording setup for the long-term recording of the network activity over 21 Days-in-Vitro (DIV). Structural and fluidic isolation between the compartments are demonstrated using transfection experiments and neurotoxin exposure, respectively