Jul
08
2009
0

Protective effect of naringin against ischemic reperfusion cerebral injury: Possible neurobehavioral, biochemical and cellular alterations in rat brain.

The present study was conducted with an aim to explore the possible role of naringin against ischemia reperfusion induced- neurobehavioral alterations, oxidative damage, cellular and histopathological alterations in cortex, striatum, hippocampus areas of brain. Male Wistar rats (200-220g) were subjected to bilateral carotid artery occlusion for 30min followed by reperfusion for 24h to induce reperfusion (I/ R) cerebral injury. Naringin (50, 100mg/kg, i.p.) was administered for 7days continuously before animals were subjected to ischemia reperfusion injury. Various behavioral tests [locomotor activity, neurological score (inclined beam test), transfer latency, resistance to lateral push] and biochemical parameters (lipid peroxidation, nitrite level, reduced glutathione, superoxide dismutase and catalase activity), mitochondrial enzyme dysfunctions (Complex I, II, III and IV) in cortex, striatum, hippocampus of brain and histopathological alterations were assessed subsequently. Seven days naringin (50 and 100mg/kg) treatment significantly improved neurobehavioral alterations (improved locomotor activity, inclined beam walking and reduced resistance to lateral push, transfer latency) as compared to control ischemia reperfusion. Naringin (50mg/kg and 100mg/kg) treatment significantly attenuated oxidative damage as indicated by reduced lipid peroxidation, nitrite concentration, restored reduced glutathione and catalase activity and mitochondrial enzyme activities in cortex, striatum, cerebellum as compared to control (ischemia reperfusion) animals. In addition, naringin treatment significantly reversed histopathological alterations in cortex, striatum, hippocampus areas as compared to control (ischemia reperfusion). Present study suggests the protective effect of naringin and its therapeutic potential against ischemia reperfusion induced and related behavioral alterations in rats.

Written by admin in: Brain Damage |
Jul
08
2009
0

Histological Studies of the Effects of Chronic Implantation of Ceramic-Based Microelectrode Arrays and Microdialysis Probes in Rat Prefrontal Cortex.

Chronic implantation of neurotransmitter measuring devices is essential for awake, behavioral studies occurring over multiple days. Little is known regarding the effects of long term implantation on surrounding brain parenchyma and the resulting alterations in the functional properties of this tissue. We examined the extent of tissue damage produced by chronic implantation of either ceramic microelectrode arrays (MEAs) or microdialysis probes. Histological studies were carried out on fixed tissues using stains for neurons (cresyl violet), astrocytes (GFAP), microglia (Iba-1), glutamatergic nerve fibers (VGLUT1), and the blood-brain barrier (SMI-71). Nissl staining showed pronounced tissue body loss with microdialysis implants compared to MEAs. The MEAs produced mild gliosis extending 50-100 mum from the tracks, with a significant change in the affected areas starting at 3 days. By contrast, the microdialysis probes produced gliosis extending 200-300 mum from the track, which was significant at 3 and 7 days. Markers for microglia and glutamatergic fibers supported that the MEAs produce minimal damage with significant changes occurring only at 3 and 7 days that return to control levels by one month. SMI-71 staining supported integrity of the blood brain barrier out to 1 week for both the microdialysis probes and the MEAs. This data support that the ceramic MEAs small size and biocompatibility are necessary to accurately measure neurotransmitter levels in the intact brain. The minimal invasiveness of the MEAs reduce tissue loss, allowing for long term (>6 month) electrochemical and electrophysiological monitoring of brain activity.

Written by admin in: Brain Damage |
Jul
08
2009
0

[Effect of restricting amino acids except methionine on mitochondrial oxidative stress.]

INTRODUCTION: Protein or methionine restriction in the diet is known to decrease reactive oxygen species (ROS) production and mitochondrial oxidative stress and to increase maximum longevity in rodents, which could explain how these changes also take place in dietary restriction. However, it is not known whether restriction of other amino acids is also involved. To clarify this question, we studied the effect of restricting all the amino acids, except methionine, of the semi-purified diet, AIN 93G, in Wistar rats. MATERIAL AND METHODS: Seven-week old male Wistar rats (n=16) were randomly divided into two groups: a control group and a group with 40% restriction of dietary amino acids except methionine. After 7 weeks of dietary treatment, the animals were sacrificed and their livers were extracted to isolate mitochondria immediately and measure ROS production and oxygen consumption; these data allowed the percentage of free radical leak to be calculated. Oxidative damage to mitochondrial DNA was calculated as 8-oxo-7,8-dihydro-2′-deoxyguanosine by HPLC-EC. RESULTS: At the end of the experimental period, a decrease in kidney weight was observed, but the weight of the liver, heart and brain was unchanged. ROS production in isolated liver mitochondria was unchanged with complex I (pyruvate/malate or glutamate/malate) or complex II (succinate) linked substrates. Maximum rates of ROS production significantly decreased with glutamate/malate+rotenone but not with pyruvate/malate+rotenone or with succinate. There were no changes in oxygen consumption with any substrate either in state 4 (resting) or in state 3 (phosphorylating). In agreement with the ROS production results, there were no differences between groups in oxidative damage to mitochondrial DNA. CONCLUSIONS: Taken together with previous results concerning methionine restriction, the results obtained in the present study clearly show that the decrease in ingestion of only one molecule, methionine, causes the decrease in ROS production and oxidative damage to mitochondrial DNA that is observed in dietary restriction in relation to the decrease in the rate of aging.

Written by admin in: Brain Damage |
Jul
08
2009
0

Expression of ephrinA5 during development and potential involvement in the guidance of the mesotriatal pathway.

Identifying guidance cues that direct axon growth to their final connections during development is of crucial interest if we aim to repair circuits damaged in adulthood following neurodegenerative disorders or common traumatic injuries. In this work, we set out to determine the ephrinA5 guidance molecule involvement in the establishment of the mouse mesostriatal pathway during development. We showed, in vitro and in vivo, that a proportion of mesencephalic dopaminergic cells express the ephrinA5 receptor, EphA5. Moreover, we observed, using stripe assays, that ephrinA5 purified protein has a repulsive effect on most of the mesencephalic dopaminergic projections. In vivo, we detected rostro-caudal and ventro-dorsal ephrinA5 protein expression gradients in the vicinity of the dopaminergic axons in the ventral telencephalon and in the striatum, during the embryonic and early postnatal development. In addition, other EphA5 ligands were also detected in the mesostriatal pathway. Together, these expression patterns suggest that, ephrinAs and more specifically ephrinA5, may be actors in the guidance of dopaminergic projections. Further studies will focus on identifying the molecular specificity of these guidance cues, taking into account the mesencephalic dopaminergic heterogeneous neuronal population. This may help to increase the integration of neuronal transplants in the mature lesioned brain or provide tools to re-establish mesostriatal circuits in vivo.

Written by admin in: Brain Damage |
Jul
08
2009
0

Transverse diffusivity of cerebral parenchyma predicts visual tracking performance in relapsing-remitting multiple sclerosis.

This study investigated the relation between cerebral damage related to multiple sclerosis (MS) and cognitive decline as determined by two classical mental tracking tests. Cerebral damage in 15 relapsing-remitting MS patients was measured by diffusion tensor imaging (DTI). Fractional anisotropy, longitudinal and transverse diffusivity were defined in the cerebral parenchyma. Cognitive performance of the MS patients was assessed with the oral response format of the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT). A significant correlation was found between performance on the SDMT and the fractional anisotropy in the brain. This correlation was predominantly induced by transverse diffusivity. Transverse diffusivity refers to the diffusion across fibers rather than along the fibers and is believed to be a specific marker for axonal loss and demyelination associated with MS. No significant association between DTI-measures and PASAT performance was found and this negative finding was mainly attributed to psychometric qualities. These results indicate that diffusivity along the non-principal diffusion direction, a possible signature of MS-related white matter pathology, contributes to information processing speed as measured with the SDMT, a task that requires close visual tracking and a widely used clinical marker for cognitive decline in MS.

Written by admin in: Brain Damage |
Jul
08
2009
0

[How bad is accelerated senescence in consumers of drugs of abuse?]

The aging or senescence process that follows maturation is characterized by time-related functional decline due to genetic, biochemical, physiological and anatomical degeneration in tissues and organ systems with time. Oxidative damage to mitochondrial DNA (mtDNA) in the heart and brain is inversely related to maximum life span of mammals, suggesting that accumulation of mtDNA damage is involved in the various disorders associated with aging, cancer and neurodegeneration. The suppression of stem/progenitor cell proliferation also contributes to the aging process, by reducing tissue regeneration and repair and ultimately reducing longevity. Another important factor is the intracellular deposition of lipofuscin granules (age pigment), a non-degradable polymeric material accumulated within lysosomes, which ultimately exacerbate oxidative stress levels in senescent cells. Drugs of abuse can strongly contribute to these senescence accelerating factors in the brain. Methylenedioxymethamphetamine (‘ecstasy’) and methamphetamine were shown to promote deletions in brain mtDNA. Concerning stem/ progenitor cells, it has been shown that several opiates and psychostimulants, including ecstasy, decrease the self-renewal capacity of the hippocampus by diminishing the rate of proliferation of neural progenitors and/or by impairing the long-term survival of neural precursors. Chronic alcohol consumption induces lipofuscin deposition in neurons and heart cells. These facts provide interesting hints on the potential of these drugs in accelerating brain senescence. While the extent and severity of the contribution of drugs of abuse for accelerated senescence remain uncertain, these putative aging effects add up to the dark side of drug addiction and undoubtedly require a strong research effort in the near future.

Written by admin in: Brain Damage |
Jul
08
2009
0

Neurotoxoplasmosis diagnosis for HIV-1 patients by real-time PCR of cerebrospinal fluid.

Encephalitis caused by Toxoplasma gondii is the most common cause of central nervous system damage in patients with acquired immunodeficiency syndrome (AIDS). Toxoplasma may infect any of the brain cells, thus leading to non-specific neurotoxoplasmosis clinical manifestations including focused or non-focused signs and symptoms of central nervous system malfunction. Clinical development ranges from insidious display during weeks to experiencing acute general confusion or ultimately fatal onset. Cerebral toxoplasmosis occurs in advanced stages of immunodeficiency, and the absence of anti-toxoplasmosis antibodies by the immunofluorescence method does not allow us to rule out its diagnosis. As specific therapy begins, diagnosis confirmation is sought through clinical and radiological response. There are few accurate diagnosis methods to confirm such cases. We present a method for T. gondii DNA detection by real time PCR-Multiplex. Fifty-one patients were evaluated; 16 patients had AIDS and a presumptive diagnosis for toxoplasmosis, 23 patients were HIV-positive with further morbidities except neurotoxoplasmosis, and 12 subjects were HIV-negative control patients. Real time PCR-Multiplex was applied to these patients’ cephalorachidian liquid with a specific T. gondii genome sequence from the 529bp fragment. This test is usually carried out within four hours. Test sensitivity, specificity, positive predictive value, and negative predictive value were calculated according to applicable tables. Toxoplasma gondii assay by real time Multiplex of cephalorachidian fluid was positive for 11 out of 16 patients with AIDS and a presumptive diagnosis for cerebral toxoplasmosis, while none of the 35 control patients displayed such a result. Therefore, this method allowed us to achieve 68.8% sensitivity, 100% specificity, 100% positive predictive value, and 87.8% negative predictive value. Real time PCR on CSF allowed high specificity and good sensitivity among patients who presumably had cerebral toxoplasmosis. Since this is a low invasive method, it could be included in the diagnosis algorithm of patients with AIDS and central nervous system damage.

Written by admin in: Brain Damage |
Jul
08
2009
0

Early onset Paget’s disease of bone caused by a novel mutation (78dup27) of the TNFRSF11A gene in a Chinese family.

AbstractAim:A previous study showed that individuals of Japanese descent affected by early onset familial Paget’s disease of bone (PDB) carried a 27-bp duplication at position 75 (75dup27) in the TNFRSF11A gene encoding RANK. Here we report the identification of a novel mutation (78dup27) in exon 1 of TNFRSF11A in a Chinese family with early onset PDB.Methods:We conducted clinical and genetic studies in a non-consanguineous Chinese family with early onset PDB. The entire coding region of TNFRSF11A was amplified and directly sequenced directly.Results:A novel 27-bp duplication in exon 1 (78dup27) in TNFRSF11A was found in four affected individuals and one asymptomatic individual. Although this duplication was the same length as the previously identified mutation (27 bp, from bases 78 to 104), in our patients the nine duplicated amino acids in the RANK signal peptide were LLLLCALLA. The phenotypes of affected individuals in this family overlapped with both early onset PDB and classic PDB, but several distinguishing features were found in our patients. The key difference between our familial PDB and the Japanese early onset PDB was the age of onset, which in most of our patients was during their late 20s (except for the propositus’ niece). Another notable difference was that the propositus’ son (24 years old), who carried the 78dup27 mutation, had no clinical symptoms or bone abnormalities, except for increased serum ALP, OC and CTX.Conclusion:Our findings may provide a better understanding of the clinical features of early onset PDB and support the notion of a hot spot for mutations in exon 1 of the TNFRSF11A gene.Acta Pharmacologica Sinica advance online publication, 6 July 2009; doi: 10.1038/aps.2009.90.

Written by admin in: Ischemic Brain Damage |
Jul
08
2009
0

Cytokines and schizophrenia: Microglia hypothesis of schizophrenia.

The etiology of schizophrenia remains unclear, while there has been a growing amount of evidence for the neuroinflammation and immunogenetics, which are characterized by an increased serum concentration of several pro-inflammatory cytokines. Despite the fact that microglia comprise only <10% of the total brain cells, microglia respond rapidly to even minor pathological changes in the brain and may contribute directly to the neuronal degeneration by producing various pro-inflammatory cytokines and free radicals. In many aspects, the neuropathology of schizophrenia has recently been reported to be closely associatedwith microglial activation. Previous studies have shown the inhibitory effects of some typical/atypical antipsychotics on the release of inflammatory cytokines and free radicals from activated microglia, both of which have recently been known to cause a decrease in neurogenesis as well as white matter abnormalities in the brains of patients with schizophrenia. The microglia hypothesis of schizophrenia may shed new light on the therapeutic strategy for schizophrenia.

Written by admin in: Ischemic Brain Damage |
Jul
08
2009
0

Sjögren Syndrome or Sjögren Disease? The Histological and Immunological Bias Caused by the 2002 Criteria.

The current 2002 classification criteria do not cover the broad clinical and immunological heterogeneity of primary Sjögren syndrome (SS), since five of the six criteria focus exclusively on glandular involvement and the remaining criterion is the mandatory presence of anti-Ro/La antibodies. The aim of this study was to analyze the clinical features of patients with a well-established diagnosis of primary SS who do not fulfill the 2002 classification criteria. Five hundred seven patients diagnosed with primary SS (1993 criteria) were consecutively included and followed up. Two hundred twenty-one (44%) patients did not fulfill the 2002 criteria. These patients were older at diagnosis (p < 0.001) and had a lower frequency of parotid enlargement (p = 0.002), fever (p = 0.041), arthritis (p = 0.041), vasculitis (p = 0.050), peripheral neuropathy (p = 0.002), cranial nerve involvement (p = 0.015), raised erythrocyte sedimentation rate ( ESR) levels (p < 0.001), anemia (p < 0.001), leukopenia (p = 0.037), hypergammaglobulinemia (p < 0.001), positive rheumatoid factor ( RF; p = 0.002), and cryoglobulinemia (p = 0.049) in comparison with those fulfilling 2002 criteria. However, there were no significant differences in the prevalence of sicca features, diagnostic tests, overall systemic involvement, antinuclear antibodies , complement levels, development of B-cell lymphoma, or survival. Patients with anti-Ro antibodies had the highest frequencies of systemic features, hematological abnormalities, and altered immunological markers. In conclusion, patients fulfilling the 2002 criteria, who have either a specific histological diagnosis (lymphocytic infiltration) or highly specific autoantibodies (Ro/La), might well be considered to have Sjögren “disease.” In contrast, etiopathogenic mechanisms other than lymphocytic-mediated epithelial damage could be involved in patients with negative Ro and negative biopsy, in whom the term Sjögren “syndrome” seems more adequate.

Written by admin in: Ischemic Brain Damage |

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