The nerve growth factor (NGF): chemical properties and metabolic effects

Effects of BNN27, a novel C17-spiroepoxy steroid derivative, on experimental retinal detachment-induced photoreceptor cell death

Retinal detachment (RD) leads to photoreceptor cell death secondary to the physical separation of the retina from the underlying retinal pigment epithelium. Intensifying photoreceptor survival in the detached retina could be remarkably favorable for many retinopathies in which RD can be seen. BNN27, a blood-brain barrier (BBB)-permeable, C17-spiroepoxy derivative of dehydroepiandrosterone (DHEA) has shown promising neuroprotective activity through interaction with nerve growth factor receptors, TrkA and p75^NTR. Here, we administered BNN27 systemically in a murine model of RD. TUNEL⁺ photoreceptors were significantly decreased 24 hours post injury after a single administration of 200 mg/kg BNN27. Furthermore, BNN27 increased inflammatory cell infiltration, as well as, two markers of gliosis 24 hours post RD. However, single or multiple doses of BNN27 were not able to protect the overall survival of photoreceptors 7 days post injury. Additionally, BNN27 did not induce the activation/phosphorylation of TrkA^Y490 in the detached retina although the mRNA levels of the receptor were increased in the photoreceptors post injury. Together, these findings, do not demonstrate neuroprotective activity of BNN27 in experimentally-induced RD. Further studies are needed in order to elucidate the paradox/contradiction of these results and the mechanism of action of BNN27 in this model of photoreceptor cell damage.

Scaffolds for 3D in vitro culture of neural lineage cells

Understanding how neurodegenerative disorders develop is not only a key challenge for researchers but also for the wider society, given the rapidly aging populations in developed countries. Advances in this field require new tools with which to recreate neural tissue in vitro and produce realistic disease models. This in turn requires robust and reliable systems for performing 3D in vitro culture of neural lineage cells. This review provides a state of the art update on three-dimensional culture systems for in vitro development of neural tissue, employing a wide range of scaffold types including hydrogels, solid porous polymers, fibrous materials and decellularised tissues as well as microfluidic devices and lab-on-a-chip systems. To provide some context with in vivo development of the central nervous system (CNS), we also provide a brief overview of the neural stem cell niche, neural development and neural differentiation in vitro. We conclude with a discussion of future directions for this exciting and important field of biomaterials research.

STATEMENT OF SIGNIFICANCE

Neurodegenerative diseases, including dementia, Parkinson's and Alzheimer's diseases and motor neuron diseases, are a major societal challenge for aging populations. Understanding these conditions and developing therapies against them will require the development of new physical models of healthy and diseased neural tissue. Cellular models resembling neural tissue can be cultured in the laboratory with the help of 3D scaffolds - materials that allow the organization of neural cells into tissue-like structures. This review presents recent work on the development of different types of scaffolds for the 3D culture of neural lineage cells and the generation of functioning neural-like tissue. These in vitro culture systems are enabling the development of new approaches for modelling and tackling diseases of the brain and CNS.

Genetic resistance to lethal flaviviral encephalitis. III. Replication of Banzi virus in vitro and in vivo in tissues of congeneic susceptible and resistant mice

The replication of Banzi virus, flavivirus, was compared in vitro and in vivo in tissues of congenic mice genetically resistant (C3H/RV) or genetically susceptible (C3H/He) to lethal infection. Ultrastructural changes in brains of resistant and susceptible adult mice following intracerebral or intraperitoneal inoculation of virus also were compared. Banzi virus replicated equally well in monolayer cultures of infant and adult brain, stimulated and non-stimulated macrophages and embryonic cells from both strains of mice. Similarly, no significant differences were found between strains in virus growth in brain, spleen or thymus of peripherally-inoculated infant mice. In intracerebrally-inoculated adult mice, virus titers in brains of resistant mice were consistently lower than in susceptible mice. Visualization of virus particles was dependent on virus concentration in tissues. The changes in brain tissues of both strains of mice were similar, differing only in the time of onset which was noted two days later in C3H/RV mice than in C3H/He mice. These results indicate that, in the case of Banzi virus, the phenotypic expression of genetically-determined resistance of lethal flavivirus infection cannot be attributed primarily to the ability of host cells to support virus replication.

Studies on the mechanism of action of nerve growth factor

In this study, explanted chick-embryo sensory ganglia were treated with nerve growth factor, and cellular concentrations of neurotubule protein were measured chemically by a colchicine-binding assay. Even after brief time periods, ganglia treated with growth factor were enriched in neurotubule protein, as compared with untreated (control) ganglia. Furthermore, studies with ganglia treated with both vincristine and growth factor demonstrated that neurotubule protein synthesis can occur even though neurite outgrowth is abolished. Several lines of evidence indicate that the growth factor stimulates de novo synthesis of neurotubule subunit protein, and that this effect precedes neurite extension. Like nerve growth factor, dibutyryl cyclic AMP also stimulates neurite outgrowth from embryonic sensory ganglia, yet it does not increase neurotubule protein levels. Available information suggests that the ability of growth factor to elicit rapid neurite outgrowth is closely related to its ability to increase cellular neurotubule levels. Cyclic AMP appears to stimulate neurite outgrowth by a different mechanism.

Sympathetic nerve cell destruction in newborn mammals by 6-hydroxydopamine

A selective and permanent destruction of sympathetic ganglia was achieved by injecting 6-hydroxydopamine in newborn animals. A lifelong chemical sympathectomy may thus be obtained. The process of cell damage and destruction is substantially different from that produced with an antiserum to a specific nerve growth factor.

Immunochemical properties of the nerve growth factor

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