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Aug 2016 DOI 10.14302/issn.2474-9273.jbtm-16-1151
Xing GuoqiangCorresponding author
Departments of Anesthesiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
Oxidative stress mediated neural cell death is thought to be involved in the progression of secondary cell injury following brain trauma. Agents that can block oxidative stress-related injury could be potential therapies for TBI. Resveratrol, a polyphenol found in plants and red wine, is cytoprotective due to its potent antioxidant activities. To further understand how resveratrol could affect oxidative stress-induced injury, we hypothesized that the cytoprotective activities of resveratrol could be dose-dependent. In this study, resveratrol-induced cytoprotection was evaluated in cultured astrocytes. Primary rat astrocytes were cultured in T-75 flasks to a confluence of 80% before being plated onto 96-well plates. After 24 hours of acclimation, astrocytes were treated with various doses of hydrogen peroxide (H2O2) (0.1, 0.25, 0.5 and 1 µM) and resveratrol (25, 50, 75, 100 µM), respectively. Cell viability was determined 24 hours later using Alamar Blue Assay. Treatment of astrocytes with 0.5 mM H2O2, left 65% of astrocytes non-viable whereas treatment of astrocytes with 0.1 mM H2O2 had no effect on astrocytes viability; whereas 1 mM, H2O2 caused total loss of astrocyte viability. Resveratrol treatment at 75 µM and 100 µM has reduced 0.5 mM H2O2-induced cytotoxicity in astrocytes by 50%. Immunostaining with GFAP also confirmed these findings about the cytoprotective effects of resveratrol in astrocytes exposed to H2O2. These results suggest that resveratrol could be a potential neuroprotective agent in TBI due to its antioxidant properties. Further studies are needed to evaluate the long- term effects of resveratrol in animal models of TBI.
Apr 2017 DOI 10.14302/issn.2572-5424.jgm-17-1482
H Baslow MorrisCorresponding author
Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research
Canavan disease (CD) is a globally occurring but rare human spongiform leukodystrophy that is associated with inborn errors affecting the activity of aspartoacylase (ASPA), an enzyme highly expressed in oligodendrocytes that hydrolyzes N-acetylaspartate (NAA). Lack of ASPA activity is associated with the inability of oligodendrocytes to build or maintain axon-enveloping myelin sheaths. The primary source of NAA in brain is neurons, cells that synthesize but cannot catabolize it. Neurons also synthesize N-acetylaspartylglutamate (NAAG) from NAA and glutamate but cannot catabolize this substance as well. For their metabolism, these substances are released to extracellular fluid and are metabolized by oligodendrocyte ASPA and astrocyte NAAG peptidase respectively. A hypothesis developed suggested that the cause of the leukodystrophy component in CD was due to release of NAAG by neurons at white matter nodes of Ranvier, its catabolism by astrocytes forming NAA and increased osmotic-hydrostatic pressure as a result of its buildup at these nodes due to the lack of ASPA activity. In this communication, we provide evidence supporting this hypothesis and comment on the cause and possible cure for human CD.
Jun 2016 DOI 10.14302/issn.2572-5424.jgm-16-1028
H Baslow MorrisCorresponding author
Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, 10962, USA.
N-acetylaspartylglutamate (NAAG) is the highest concentration dipeptide present in brain. It is found primarily in neurons but its function is unclear. NAAG is synthesized by neurons from N-acetylaspartate and glutamate (Glu), maintained at mM concentrations and is released non-synaptically to extracellular fluid (ECF). NAAG is a non-excitatory form of Glu, and is targeted to the metabotropic group II Glu receptor 3 (mGluR3) on the surface of astrocytes. After docking with the receptor, Glu is released by the action of NAAG peptidase. Previously, it was shown for the first time that an NAAG-peptidase inhibitor reduced global cerebral blood flow (CBF) in mouse brain but did not affect their physical performance. Recently, it has been demonstrated that there are two separate systems involved in neurovascular coupling by astrocytes, one is a rapid focal phasic response providing energy for stimulation-induced neuronal activity, and the other a slower global tonic response providing energy for ongoing metabolic activities. Many neurovascular coupling mechanisms are known that regulate phasic changes in CBF, but how the brain accomplishes tonic control is unknown. In this paper we bring together two separate lines of inquiry, the decades’ long search for the function of NAAG, and the more recent search for the mechanism of tonic neurovascular control. Herein, we present evidence that NAAG is the neurovascular coupling agent that regulates tonic changes in CBF via the astrocyte mGluR3-NAAG peptidase connection.
Jun 2014 DOI 10.14302/issn.2372-6601.jhor-14-378
Kulma-Kreft MonikaCorresponding author
Department of Radiotherapy and Medical Oncology, Gdynia Cancer Center, Gdynia
Progressive multifocal leukoencephalopathy (PML) is a rare complication associated, inter alia, with rituximab-based lymphoma treatment. PML diagnosis is made easier with the criteria recently published by the American Academy of Neurology. Unambiguous diagnosis of PML can be achieved by demonstration of the histopathological triad comprising:(1) demyelination, (2) bizarre astrocytes and (3) enlarged oligodendroglial nuclei together with detection of viral particles by electron microscopy. However, symptoms of PML may be similar to those observed during lymphoma progression into the central nervous system (CNS). Here we report the case of a patient with diffuse large B-cell lymphoma (DLBCL) treated with R-CHOP who developed clinical signs indicating PML. Intravital diagnostic methods failed to yield an unequivocal diagnosis of PML or lymphoma progression in the CNS. However, a post-mortem examination of brain biopsy specimens performed by electron microscopy demonstrated lesions typical for PML and the presence of viral particles. In addition, immunohistochemical assays identified a massive infiltration of lymphoma cells. The case thus suggests either the extremely rare coexistence of two complications: lymphoma CNS infiltration and PML or induction structural CNS lesions by lymphoma infiltration indistinguishable from PML. The presented findings thus highlight the need for a further review of the current diagnostic criteria for PML.