Some markers of neuronal damage in cerebrospinal fluid of multiple sclerosis patients in relapse.

In this paper the performance of cerebrospinal fluid (CSF) protein biomarkers important for monitoring damage of brain astrocytes and neurons for MS is reviewed. We estimated neurofilament, tau and phospho-tau proteins, β-APP, Aβ, S-100B and neuron-specific enolase in CSF of MS patients during relapse. We noted elevation of neurofilament, tau and phospho-tau proteins, S-100B, neuron-specific enolase and c-terminal epitopes of β-APP; concomitantly decrease of Aβ was observed.

Free radical peroxidation products in cerebrospinal fluid and serum of patients with multiple sclerosis after glucocorticoid therapy.

Multiple sclerosis (MS) patients were found to have elevated thiobarbituric acid reactive material levels, increased soluble sulfhydryl groups and reduced protein sulfhydryl groups in cerebrospinal fluid and serum, and slightly reduced superoxide dismutase in serum, which suggested disease activating free radical peroxidation. Moreover, levels of these varied across methylprednisolone (MP) therapy. We observed significant differences in the levels of peroxidation products between MS patients and controls.

Homocysteine-induced acute excitotoxicity in cerebellar granule cells in vitro is accompanied by PP2A-mediated dephosphorylation of tau.

Our results demonstrate that acute exposure of primary rat cerebellar granule cell cultures to homocysteine at millimolar concentrations induces a glutamate receptor-mediated decrease in tau protein phosphorylation, which is accompanied by excitotoxic neuronal damage. This contrasts with the previously reported hyperphosphorylation of tau in homocysteine-treated neurons, and with the assumption that hyperhomocysteinemia is one of the risk factors in Alzheimer disease, in which abnormal hyperphosphorylation of tau protein leads to neurofibrillary degeneration. The mechanisms of homocysteine neurotoxicity have been explained mainly either by disturbances in methylation processes, that may also lead to the accumulation of phosphorylated tau due to reduced activity of tau-selective protein phosphatase 2A, or by excitotoxicity.

Differential changes in phosphorylation of tau at PHF-1 and 12E8 epitopes during brain ischemia and reperfusion in gerbils.

Cortical neurons are vulnerable to ischemic insult, which may cause cytoskeletal changes and neurodegeneration. Tau is a microtubule-associated protein expressed in neuronal and glial cells. We examined the phosphorylation status of tau protein in the gerbil brain cortex during 5 min ischemia induced by bilateral common carotid artery occlusion followed by reperfusion for 20 min to 7 days.

The immature endothelial cell in new vessel formation following surgical injury in rat brain.

Objectives: We investigated neovasculatization in the cerebral cortex of the adult rat after surgical brain injury by ultrastructural, immunocytochemical and immunochemical means. Previously we described endothelial-like cell that participates in new vessel formation on plasma proteins that served as a provisional matrix in the region immediately adjacent to the traumatic injury. In the present study we describe new vessel formation in the multistep process with the alterations in endothelial-like cell immunophenotype.

2-deoxyglucose induces beta-APP overexpression, tau hyperphosphorylation and expansion of the trans-part of the Golgi complex in rat cerebral cortex.

The effects of a single intraperitoneal injection of a non-metabolizable glucose analog 2-deoxyglucose (2-DG, 500 mg/kg) on the levels of beta-APP expression, and phosphorylated and unphosphorylated tau protein in the rat cerebral cortex were investigated. The effects of 2-DG on the ultrastructure of cortical neurons with particular emphasis on the morphology of the Golgi apparatus, and on brain bioenergetics assessed by in vivo 31P-MRS technique were also evaluated. Seven and a half hours after injection of 2-deoxyglucose a significant increase in brain cortex beta-APP expression, increased tau phosphorylation, and a marked relative expansion of the trans- part of the Golgi intracellular secretory pathway in cortical neurons has been found.

Cerebrospinal fluid free-radical peroxidation products and cognitive functioning patterns differentiate varieties of normal pressure hydrocephalus.

The aims of the study were as follows: first, to verify the hypothesis that free radical peroxidation may be one of the factors implicated in pathophysiology of normal pressure hydrocephalus (NPH) and, second, to find out whether these biochemical characteristics together with neuropsychological cognitive deficits can differentiate between various types of NPH. This provides prognostic criteria for selection of patients for shunt surgery. Lipid peroxidation was measured in terms of thiobarbituric acid-reactive material (TBAR) and protein sulphydryl (SH) groups were measured as CSF content.

N-methyl-d-aspartate receptor-mediated processing of beta-amyloid precursor protein in rat hippocampal slices: in vitro--superfusion study.

Abnormal proteolytic degradation of the beta amyloid precursor protein (beta-APP) may result in accumulation of potentially neurotoxic beta amyloid (betaA). The role of various receptors in the regulation of beta-APP processing has been suggested. This study aimed to determine how NMDA receptors and Ca2+ ions regulate proteolysis of beta-APP in rat hippocampus in vitro.

Excitotoxicity-induced expression of amyloid precursor protein (beta-APP) in the hippocampus and cortex of rat brain. an electron-microscopy and biochemical study.

After stereotaxic microinjection of N-methyl-D-aspartate (NMDA) or alpha-amino-3-hydroxy-5-methyl isoxazole-4-propionic acid (AMPA) to CA1 of rat hippocampus, the animals were sacrificed: 0 h, 2 h, 12 h, 24 h and 3 days after the insult. Other groups of animals before microinjection of the excitotoxins received intraperitoneal injection of dizocilpine (MK-801). Expression of beta-APP was assessed by immunohistochemical and immunobiochemical methods, and the results were correlated with changes in tissue ultrastructure observed in the electron microscopy.

Differences between rats and rabbits in NMDA receptor-mediated calcium signalling in hippocampal neurones.

In vivo microdialysis combined with the measurement of (45)Ca(2+) efflux from prelabelled hippocampus demonstrated a pronounced N-methyl-D-aspartate (NMDA)-evoked (45)Ca(2+) release to the dialysate in the rat dentate gyrus (DG) and CA1, whereas in rabbit a slight release of (45)Ca(2+) was observed only in the DG. In vitro, we noticed that the NMDA-evoked increase in Fura-2 detected intracellular Ca(2+) concentration in synaptoneurosomes from the rat, but not from the rabbit hippocampus, was strongly inhibited by the ryanodine receptor (RyR) antagonists dantrolene and ryanodine. To establish the mechanism of these differences, we characterised their possible dependence on the expression of RyR and their co-localisation with the calcium binding protein calbindin D(28k).

Induction of Alzheimer-specific Tau epitope AT100 in apoptotic human fetal astrocytes.

In Alzheimer's and other neurodegenerative diseases, hyperphosphorylated tau accumulates in affected neuronal and glial cells in the form of paired helical filaments (PHFs). This tau binds antibody AT100, which recognizes the double phosphorylation site (Thr212/Ser214) that is not present in normal biopsy tau. In primary cultures, highly enriched (>98%) in astrocytes of human fetal brain, three polypeptides of 52, 64, and 70 kD showed immunoreactivity with tau antibodies against non-phosphorylated epitopes, accounting for 88, 12, and <1%, respectively, of the total reactivity.

Conformation of paired helical filaments blocks dephosphorylation of epitopes shared with fetal tau except Ser199/202 and Ser202/Thr205.

To determine if the high phosphate content of paired helical filaments (PHFs) in Alzheimer's disease (AD) is a result of limited access to filament phosphorylation sites, we studied in vitro dephosphorylation of intact PHFs, PHFs with filamentous structure abolished by formic acid treatment (PHF(FA)) and fetal human tau protein. Samples were treated with alkaline phosphatase for up to 24 h at 37 degrees C and then immunoblotted with eight well characterized tau antibodies, that recognize two phosphorylation-insensitive sites and six phosphorylation-sensitive epitopes at Thr181, Ser199/202, Ser202/Thr205, Thr231, Ser262/356 and Ser396/404. Intact PHFs were effectively dephosphorylated only at the two N-terminal epitopes Ser199/202 and Ser202/Thr205, with little change in electrophoretic mobility.

Hydroxylamine attenuates the effects of simulated subarachnoid hemorrhage in the rat brain and improves neurological outcome.

Some of the neurological deficits that emerge after aneurysmal subarachnoid hemorrhage (SAH) in humans are presumably caused by ischemic brain damage consequential to SAH-induced delayed cerebral vasospasm. This vasospasm probably results from an imbalance among vasoactive factors released from both the clot formed by extravasated blood and adjacent tissues, and in particular from a decrease in the endothelium-derived relaxing factor nitric oxide (NO). Brain ischemia is also known to elevate brain production and deposition of beta-amyloid, and to induce a delayed increase in total NO synthase (NOS) activity due to induction of expression of so-called induced NOS isoform, phenomena that may secondarily contribute to SAH-related brain damage.

Changes in oxidative stress in the rat brain during post-cardiac arrest reperfusion, and the effect of treatment with the free radical scavenger idebenone.

The study was designed to determine the effect of idebenone, an electron-trapping agent and free radical scavenger capable of crossing the blood-brain barrier, on cardiac arrest-induced oxidative brain stress. Stress indices used were the brain contents of thiobarbituric acid-reactive material (TBAR), conjugated dienes and protein and non-protein thiols. Twenty-four hours after receiving one oral dose of placebo or 100 mg kg(-1) idebenone, the rats were anaesthetized with diethyl ether and either decapitated immediately, or subjected to 7.

Tau released from paired helical filaments with formic acid or guanidine is susceptible to calpain-mediated proteolysis.

Paired helical filaments (PHFs), a characteristic neuropathologic finding in Alzheimer's disease brain, are abnormal fibrillary forms of hyperphosphorylated tau (PHF-tau), which have been shown to be highly resistant to calpain digestion. Either excessive phosphorylation or fibrillary arrangement of tau proteins in PHFs may play a role in proteolytic resistance by limiting access to calpain recognition/digestion sites. To determine the contribution of the fibrillary conformation, isolated PHFs were subjected to treatment with either formic acid or guanidine.