NeuroEPO Preserves Neurons from Glutamate-Induced Excitotoxicity.

Many experimental studies show that erythropoietin (EPO) has a neuroprotective action in the brain. EPO in acute and chronic neurological disorders, particularly in stroke, traumatic brain injury, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, has neuroprotective effects. We previously reported the neuroprotective effect of NeuroEPO, a low sialic form of EPO, against oxidative stress induced by glutamate excitotoxicity. In this paper, we analyze the effect of NeuroEPO against apoptosis induced by glutamate excitotoxicity in primary neuronal cultures obtained from the forebrains of Wistar rat embryos after 17 days of gestation. Excitotoxicity was induced after nine days of in vitro culture by treatment with a culture medium containing 100µM glutamate for 15 min. To withdraw glutamate, a new medium containing 100 ng NeuroEPO/mL was added. Apoptosis was analyzed after 24 h. Images obtained by phase contrast microscopy show that neurons treated with glutamate exhibit cell body shrinkage, loss of dendrites that do not make contact with neighboring cells, and that NeuroEPO was able to preserve the morphological characteristics of the control. Immunocytochemistry images show that the culture is essentially pure in neurons; that glutamate causes cell mortality, and that this is partially avoided when the culture medium is supplemented with NeuroEPO. Activation of intrinsic apoptotic pathways was analyzed. The decreases in Bcl-2/Bax ratio, increase in the release of cytochrome c, and in the expression and activity of caspase-3 observed in cells treated with glutamate, were restored by NeuroEPO. The results from this study show that NeuroEPO protects cortical neurons from glutamate-induced apoptosis via upregulation of Bcl-2 and inhibit glutamate-induced activation of caspase-3.

Unconventional EGF-induced ERK1/2-mediated Kv1.3 endocytosis.

The potassium channel Kv1.3 plays roles in immunity, neuronal development and sensory discrimination. Regulation of Kv1.3 by kinase signaling has been studied. In this context, EGF binds to specific receptors (EGFR) and triggers tyrosine kinase-dependent signaling, which down-regulates Kv1.3 currents. We show that Kv1.3 undergoes EGF-dependent endocytosis. This EGF-mediated mechanism is relevant because is involved in adult neural stem cell fate determination. We demonstrated that changes in Kv1.3 subcellular distribution upon EGFR activation were due to Kv1.3 clathrin-dependent endocytosis, which targets the Kv1.3 channels to the lysosomal degradative pathway. Interestingly, our results further revealed that relevant tyrosines and other interacting motifs, such as PDZ and SH3 domains, were not involved in the EGF-dependent Kv1.3 internalization. However, a new, and yet undescribed mechanism, of ERK1/2-mediated threonine phosphorylation is crucial for the EGF-mediated Kv1.3 endocytosis. Our results demonstrate that EGF triggers the down-regulation of Kv1.3 activity and its expression at the cell surface, which is important for the development and migration of adult neural progenitors.

Developmental expression of the oligodendrocyte myelin glycoprotein in the mouse telencephalon.

The oligodendrocyte myelin glycoprotein is a glycosylphosphatidylinositol-anchored protein expressed by neurons and oligodendrocytes in the central nervous system. Attempts have been made to identify the functions of the myelin-associated inhibitory proteins (MAIPs) after axonal lesion or in neurodegeneration. However, the developmental roles of some of these proteins and their receptors remain elusive. Recent studies indicate that NgR1 and the recently discovered receptor PirB restrict cortical synaptic plasticity. However, the putative factors that trigger these effects are unknown. Because Nogo-A is mostly associated with the endoplasmic reticulum and myelin associated glycoprotein appears late during development, the putative participation of OMgp should be considered. Here, we examine the pattern of development of OMgp immunoreactive elements during mouse telencephalic development. OMgp immunoreactivity in the developing cortex follows the establishment of the thalamo-cortical barrel field. At the cellular level, we located OMgp neuronal membranes in dendrites and axons as well as in brain synaptosome fractions and axon varicosities. Lastly, the analysis of the barrel field in OMgp-deficient mice revealed that although thalamo-cortical connections were formed, their targeting in layer IV was altered, and numerous axons ectopically invaded layers II-III. Our data support the idea that early expressed MAIPs play an active role during development and point to OMgp participating in thalamo-cortical connections.

Efficacy and tolerability of a combined moxifloxacin/dexamethasone formulation for topical prophylaxis and reduction of inflammation in phacoemulsification: a comparative, double masked clinical trial.

PURPOSE: To compare the efficacy and safety of a combined 0.5% moxifloxacin and 0.1% dexamethasone formulation (Vigadexa) versus conventional dosing with 0.5% concomitant moxifloxacin (Vigamox) and 0.1% dexamethasone (Maxidex) for the prevention of infection and control of inflammation after cataract surgery. SETTING: The ophthalmology clinic and outpatient surgery suite of a public hospital in Brazil. METHODS: A prospective, randomized, double-masked, parallel-group study of 139 patients, all of which underwent phacoemulsification and intraocular lens (IOL) implantation. After random assignment, 64 eyes received the combination of topical 0.5% moxifloxacin/0.1% dexamethasone drop and 62 eyes received 0.5% moxifloxacin and 0.1% dexamethasone as separate solutions four times a day for 15 days. Baseline and postoperative assessments were made on surgery days -2, 1, 3, 8, and 15. Limitations of this study included its small size and relatively short duration of follow-up. RESULTS: There was no sign of intraocular infection at any time and only minimal inflammation beyond day 3. Physicians rated bacterial infection to be absent in both groups on days 1, 3, 8 and 15. Ninety-seven percent of patients in each group had < or = 5 cells by day 15. Objective and subjective parameters were essentially the same in both treatment groups (p > 0.05). One patient in the conventional therapy group developed viral conjunctivitis unrelated to the surgery. CONCLUSION: Treatment with the combined moxiflox acin/dexamethasone eye drops was as effective as conventional treatment in preventing infection and controlling inflammation after phacoemulsification and IOL implantation.