Impaired helix 12 dynamics due to proline 892 substitutions in the androgen receptor are associated with complete androgen insensitivity

Human Molecular Genetics (2006) 15, 921–931;     

Disappearance of the mu-opiate receptor patches in the rat neostriatum following lesioning of the ipsilateral nigrostriatal dopamine pathway with 1-methyl-4-phenylpyridinium ion (MPP+): restoration by embryonic nigral dopamine grafts

Using in vitro autoradiography, this study examined the binding of the selective mu-opiate receptor radiolabelled ligand, [3H]Tyr-D-Ala-Gly-Me-Phe-Gly-ol ([3H]DAGO) to the striatal sections of rats with long-term unilateral lesions of the nigrostriatal dopamine (DA) pathway induced by 1-methyl-4-phenylpyridinium ion (MPP+) and in animals bearing embryonic DA grafts implanted into the DA-depleted striatum. In the ipsilateral striatum of MPP+-lesioned animals, there was a complete disappearance of the mu-opiate receptor patches as well as the subcallosal streak. The normal pattern of mu-binding sites in the patches reappeared following reinnervation of the DA-depleted striatum by the DA-grafts. These findings suggest that mu-opiate receptor patches in the striatum are localised on nigrostriatal DA afferent terminals. However, it is possible that trans-synaptic or postsynaptic changes also contribute to the profound alterations in striatal mu-opiate binding patterns revealed in this study.     

Interactions between meningeal cells and astrocytes in vivo and in vitro.

At the interface between the meninges and the central nervous system there is a characteristic structure known as the glia limitans, consisting of many fine interdigitating astrocyte processes which contain both GFAP and vimentin, and a basal lamina. A similar structure is set up after brain injury where meningeal cells invade the lesion. We have experimentally put astrocytes and meningeal cells in contact with one another, both in vivo and in vitro, to see whether this results in the formation of a glia limitans. Cultured meningeal cells were injected into the hippocampus of adult rats, and from 1 to 12 weeks later brains were stained were stained for GFAP and vimentin. One week after injection there was a widespread astrocytic reaction stretching up to 2 mm from the injection, the cells being stained intensely for both GFAP and vimentin. Over the next 4-6 weeks this widespread reaction subsided, the only remaining vimentin stained astrocytes, apart from those at the normal glia limitans, being in contact with the injected meningeal cells, or with meningeal cells which had migrated into the injection needle track. In vitro a structure reminiscent of the glia limitans formed where patches of astrocytes abutted meningeal cells; the astrocytes formed a layer of fine interdigitating processes all running parallel to the interface between the two cell types, and there was heavy staining for laminin and fibronectin. We conclude that a glia limitans forms wherever astrocytes and meningeal cells come into contact.     

Effects of regional striatal lesions on motor, motivational, and executive aspects of progressive-ratio performance in rats.

The striatum is implicated in response selection and performance, the dorsal striatum in sensorimotor control and habit learning, and the ventral striatum in motivation and rewarded behaviors. Ventral striatal lesions produce performance changes on food-reinforced, progressive-ratio (PR) schedules, but the effects of dorsal striatal lesions on this task are not known. In this study, neither medial nor lateral dorsal striatal lesions produced deficits on the main motivational indices of PR performance. In contrast, significant impairments were observed in motoric or "executive" aspects of performance. Motivationally related manipulations of the task (food deprivation and reward magnitude) produced some subtle lesion-specific changes in behavior on these motoric or executive aspects of performance. Findings are discussed in relation to the roles of the dorsal and ventral striatum in reward-related behaviors.     

Transmission of human cytomegalovirus from infected uterine microvascular endothelial cells to differentiating/invasive placental cytotrophoblasts

Analysis of placentas infected with human cytomegalovirus (CMV) suggested that viral transmission could involve differentiating/invasive cytotrophoblasts in villi that attach the placenta to the uterine wall. To parse the cellular components in this process, we developed a coculture system of polarized uterine microvascular endothelial cell (UtMVEC) infection with an endothelial cell-tropic pathogenic strain of CMV. Then we evaluated the potential role of neutrophils and endothelial cells in the spread of infection to differentiating cytotrophoblasts. As shown by immunocytochemistry and analysis of viral replication, CMV preferentially infected endothelial cells via apical membranes and disrupted cell junction proteins, thereby altering paracellular permeability and cell polarity. Neutralizing antibodies to CMV glycoprotein B, an envelope component that facilitates virion penetration, blocked plaque formation in polarized UtMVEC. Neutrophils transmitted CMV infection to UtMVEC, which in turn infected cytotrophoblasts. However, neutrophils did not directly infect cytotrophoblasts. These findings implicate endothelial cells from the uterine microvasculature as a potential source for CMV infection of endovascular cytotrophoblasts of the anchoring villi. Possibly the cytokine/chemokine milieu in the pregnant uterus could attract immune cells that infect endothelial cells in hybrid fetal-maternal vessels. In turn, these cells could infect endovascular cytotrophoblasts, one possible initiation point of a cascade that results in retrograde placental CMV infection.     

Age-dependence of malonate-induced striatal toxicity

Malonate is an inhibitor of cellular metabolism, which, following intrastriatal injection, induces a striatal pathology similar to that seen in Huntington's disease. In two parallel studies, we have investigated the suggested relationship between the neuronal vulnerability to metabolic toxicity and the decline in metabolic function with increasing age. The first experiment investigated malonate-induced neuronal loss in animals aged from 6 weeks up to 27 months, and the second assessed the activities of two mitochondrial enzymes, succinate dehydrogenase and cytochrome oxidase (CYTOX) in animals aged 6 weeks, 3, 8 and 18 months. In the first study, male Lister-Hooded rats received intrastriatal stereotaxic injections of malonate (0.5 or 1.0 M). Animals were killed 10 days after surgery, and the brains were stained with cresyl violet and processed for NADPH-diaphorase activity and glial fibrillary-acidic-protein (GFAP) immunohistochemistry. Animals aged 6 months and older exhibited over 60% striatal neuronal loss. However, the degree of neuronal loss did not show any age-related increase in rats between 6 and 27 months of age, indicating that the extent of malonate-induced toxicity does not increase with age in animals older than 6 months. Infusion of 0.5 M malonate produced smaller lesions, which also demonstrated a consistent extent of neuronal loss from 6 months onwards. Metabolic enzyme activities were decreased in the striatum with increasing age, although this effect was only significant for CYTOX activity. Thus, the pattern of malonate-induced neuronal loss in aged animals partially reflects the changes in metabolic activity during ageing.     

Variations in Safe Sleep Practices and Beliefs: Knowledge is not Enough

Maternal and Child Health Journal - Sleep-related infant deaths in the District of Columbia (DC) varies, with rates in certain geographical areas three times higher than DC and seven times higher...     

The effect of microglia on embryonic dopaminergic neuronal survival in vitro: diffusible signals from neurons and glia change microglia from neurotoxic to neuroprotective

When embryonic dopaminergic neurons are transplanted into the adult brain, approximately 95% die within a few days. To assess whether microglia activated during transplantation might be responsible for this rapid death, we examined the effect of microglia on rat embryonic dopaminergic neurons in vitro. Conditioned medium from 7-day-old microglia was found to decrease the number of dopamine neurons surviving in primary culture, but activation of the microglia with N-formyl-methionyl-leucyl-phenylalanine (FMLP) or Zymosan A did not increase the toxicity of the conditioned medium. We next tested the effect of coculturing microglia and dopaminergic neurons by placing microglia in semipermeable well inserts over the neuronal cultures. The presence of microglia now increased dopaminergic neuronal survival, microglial activation again having no effect. To increase yet further the possible interactions between microglia and neurons, the mesencephalic cells and microglia were mixed together and placed as a tissue in three-dimensional culture, and here again the presence of microglia increased dopaminergic neuronal survival with no effect of activation. Contact of microglia with the mesencephalic cells therefore converted them from being toxic to dopaminergic neurons to promoting their survival. The change in microglial effect from toxic to protective was caused by soluble molecules secreted by cells in the neuronal cultures, as conditioned medium derived from microglia-neuronal cocultures also had a dopaminergic neuron survival effect, indicating that microglia in cocultures behave differently from microglia removed from neuronal and glial influence. Microglia cocultured with either neurons or astrocytes downregulated inducible nitric oxide synthase (iNOS), indicating a decrease in the production of nitric oxide and possibly other toxic molecules. These findings indicate that in their natural environment, microglia are likely to be beneficial for the survival of embryonic dopaminergic grafts.