MAO-B Elevation in Mouse Brain Astrocytes Results in Parkinson's Pathology

Age-related increases in monoamine oxidase B (MAO-B) may contribute to neurodegeneration associated with Parkinson's disease (PD). The MAO-B inhibitor deprenyl, a long-standing antiparkinsonian therapy, is currently used clinically in concert with the dopamine precursor L-DOPA. Clinical studies suggesting that deprenyl treatment alone is not protective against PD associated mortality were targeted to symptomatic patients. However, dopamine loss is at least 60% by the time PD is symptomatically detectable, therefore lack of effect of MAO-B inhibition in these patients does not negate a role for MAO-B in pre-symptomatic dopaminergic loss. In order to directly evaluate the role of age-related elevations in astroglial MAO-B in the early initiation or progression of PD, we created genetically engineered transgenic mice in which MAO-B levels could be specifically induced within astroglia in adult animals. Elevated astrocytic MAO-B mimicking age related increase resulted in specific, selective and progressive loss of dopaminergic neurons in the substantia nigra (SN), the same subset of neurons primarily impacted in the human condition. This was accompanied by other PD-related alterations including selective decreases in mitochondrial complex I activity and increased mitochondrial oxidative stress. Along with a global astrogliosis, we observed local microglial activation within the SN. These pathologies correlated with decreased locomotor activity. Importantly, these events occurred even in the absence of the PD-inducing neurotoxin MPTP. Our data demonstrates that elevation of murine astrocytic MAO-B by itself can induce several phenotypes of PD, signifying that MAO-B could be directly involved in multiple aspects of disease neuropathology. Mechanistically this may involve increases in membrane permeant H2O2 which can oxidize dopamine within dopaminergic neurons to dopaminochrome which, via interaction with mitochondrial complex I, can result in increased mitochondrial superoxide. Our inducible astrocytic MAO-B transgenic provides a novel model for exploring pathways involved in initiation and progression of several key features associated with PD pathology and for therapeutic drug testing

Epstein–Barr virus and Hodgkin’s lymphoma in Cairo, Egypt

Fifty-five consecutive cases of Hodgkin’s lymphoma (HL), collected between 1996 and 1998 from Cairo, Egypt, were histologically subtyped, phenotyped, and then studied for the presence of Epstein–Barr virus (EBV). We used immunohistochemical stains for EBV latent membrane protein 1 (LMP-1) and in situ hybridization stains for EBV-encoded small RNA (EBER-1) transcripts. Forty-five cases (82%) had classic HL (cHL), and ten cases (18%) had nodular lymphocyte predominant HL (NLPHL), with each group expressing its typical phenotype. LMP-1 stains were positive in 63% and 0% of cHL and NLPHL cases, respectively. EBER-positive Reed–Sternberg cells and variants were also present in 62% and 0% of each group, respectively. The cHL cases showed variable EBER positivity: nodular sclerosis, 58%; mixed cellularity, 100%; lymphocyte depletion, 100%; and unclassifiable, 67%. Our findings are similar to those from other developing countries and point towards a pathogenic role of EBV in cHL