Open angle glaucoma is defined as a progressive and time-dependent death of retinal ganglion cells concomitant with high intraocular pressure, leading to loss of visual field. Because neurotrophins are a family of growth factors that support neuronal survival, we hypothesized that quantitative and qualitative changes in neurotrophins or their receptors may take place early in ocular hypertension, preceding extensive cell death and clinical features of glaucoma. We present molecular, biochemical, and phenotypic evidence that significant neurotrophic changes occur in retina, which correlate temporally with retinal ganglion cell death. After 7 days of ocular hypertension there is a transient up-regulation of retinal NGF, while its receptor TrkA is up-regulated in a sustained fashion in retinal neurons. After 28 days of ocular hypertension there is sustained up-regulation of retinal BDNF, but its receptor TrkB remains unchanged. Throughout, NT-3 levels remain unchanged but there is an early and sustained increase of its receptor TrkC in Müller cells but not in retinal ganglion cells. These newly synthesized glial TrkC receptors are truncated, kinase-dead isoforms. Expression of retinal p75 also increases late at day 28. Asymmetric up-regulation of neurotrophins and neurotrophin receptors may preclude efficient neurotrophic rescue of RGCs from apoptosis. A possible rationale for therapeutic intervention with Trk receptor agonists and p75 receptor antagonists is proposed.

Glaucoma is defined as a chronic and progressive optic nerve neuropathy, characterized by apoptosis of retinal ganglion cells (RGC) that leads to irreversible blindness. Ocular hypertension is a major risk factor, but in glaucoma RGC death can persist after ocular hypertension is normalized. To understand the mechanism underlying chronic RGC death we identified and characterized a gene product, ␣2-macroglobulin (␣2M), whose expression is up-regulated early in ocular hypertension and remains up-regulated long after ocular hypertension is normalized. In ocular hypertension retinal glia up-regulate ␣2M, which binds to low-density lipoprotein receptor-related protein-1 receptors in RGCs, and is neurotoxic in a paracrine fashion. Neutralization of ␣2M delayed RGC loss during ocular hypertension; whereas delivery of ␣2M to normal eyes caused progressive apoptosis of RGC mimicking glaucoma without ocular hypertension. This work adds to our understanding of the pathology and molecular mechanisms of glaucoma, and illustrates emerging paradigms for studying chronic neurodegeneration in glaucoma and perhaps other disorders.Vision impairment due to glaucoma affects 50 million people worldwide. In open angle glaucoma, visual field loss is caused by retinal ganglion cell (RGC) 3 apoptosis, concomitant with elevated intraocular pressure (IOP). Current treatments are limited to reduction of high IOP. Unfortunately, whereas these treatments are often successful at normalizing IOP, progressive RGC death and visual field loss often continue (1-3). In addition ϳ20% of patients are affected by normal tension glaucoma, a distinct optic nerve neuropathy in the absence of high IOP.Proposed mechanisms of RGC apoptosis in glaucoma include: mechanical compression of the optic nerve head preventing axonal transport of neurotrophins required for RGC survival (also known as "physiologic axotomy") (4), excitotoxic damage by hyperactive NMDA receptors, elevated glutamate, Ca 2ϩ fluxes, and nitric oxide (5, 6); ischemic and other retinal injury leading to activation of microglia (7), ␤-amyloid toxicity (8), and inflammatory damage through tumor necrosis factor-␣ (TNF␣) (9, 10). However, none of these mechanisms explain two key issues. First, all the cells in the inner retina are exposed to these deleterious effects, thus it is puzzling that RGCs are preferentially susceptible to apoptosis. Second, normalization of pressure often does not result in the complete arrest of RGC death, which continues chronically.To address these questions, we hypothesized that a short span of ocular hypertension can trigger long-lived changes in retinal gene expression, changes that are deleterious to RGCs. Five unique criteria were set to identify intraocular pressure regulated early gene (IPREG) candidates. Altered gene expression should: (i) occur specifically in the retina and be caused specifically by ocular hypertension; (ii) occur relatively early following ocular hypertension and prior to RGC damage; (iii) be long-lived; (iv) independent of the continuous p...

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Thirty-three Argentinian patients infected with hepatitis C virus (HCV) were studied for viral genotyping. The patients included 10 hemophiliac and 4 polytransfused children and 19 adults: 3 polytransfused, 7 dialyzed and 9 sporadic cases. Core-based genotyping permitted the classification of 31 samples. Genotypes II, I and V were the most frequent: 21 (63.6%), 16 (48.4%) and 10 (30.3%) of the 33 patients, respectively. Only one polytransfused patient carried genotype IV. Genotype II was detected in 7 out of 9 sporadic cases. Thirteen patients (39.3%) were coinfected with two genotypes, and 2 others were coinfected with three genotypes. The remaining 2 samples which could not be typed were characterized following the restriction fragment length polymorphism (RFLP) method, and were classified as type 1. One of these had two consecutive transitional mutations in the 5' untranslated region (5' UTR).

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