858 resultados para Postmortem Human Brain


Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND: Blood-brain barrier (BBB) breakdown is an early event in the pathogenesis of multiple sclerosis (MS). In a previous study we have found a direct stabilization of barrier characteristics after treatment of bovine brain capillary endothelial cells (BCECs) with human recombinant interferon-beta-1a (IFN-beta-1a) in an in vitro BBB model. In the present study we examined the effect of human recombinant IFN-beta-1a on the barrier properties of BCECs derived from four different species including humans to predict treatment efficacy of IFN-beta-1a in MS patients. METHODS: We used primary bovine and porcine BCECs, as well as human and murine BCEC cell lines. We investigated the influence of human recombinant IFN-beta-1a on the paracellular permeability for 3H-inulin and 14C-sucrose across monolayers of bovine, human, and murine BCECs. In addition, the transendothelial electrical resistance (TEER) was determined in in vitro systems applying porcine and murine BCECS. RESULTS: We found a stabilizing effect on the barrier characteristics of BCECs after pretreatment with IFN-beta-1a in all applied in vitro models: addition of IFN-beta-1a resulted in a significant decrease of the paracellular permeability across monolayers of human, bovine, and murine BCECs. Furthermore, the TEER was significantly increased after pretreatment of porcine and murine BCECs with IFN-beta-1a. CONCLUSION: Our data suggest that BBB stabilization by IFN-beta-1a may contribute to its beneficial effects in the treatment of MS. A human in vitro BBB model might be useful as bioassay for testing the treatment efficacy of drugs in MS.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Free-floating roller tube cultures of human fetal (embryonic age 6-10 weeks post-conception) and rat fetal (embryonic day 13) ventral mesencephalon were prepared. After 7-15 days in vitro, the mesencephalic tissue cultures were transplanted into the striatum of adult rats that had received unilateral injections of 6-hydroxydopamine into the nigrostriatal bundle 3-5 weeks prior to transplantation. Graft survival was assessed in tyrosine hydroxylase (TH)-immunostained serial sections of the grafted brains up to post-transplantation week 4 for the human fetal xenografts and post-transplantation week 11 for the rat fetal allografts. D-amphetamine-induced rotation was monitored up to 10 weeks after transplantation in the allografted animals and compared with that of lesioned-only control animals. All transplanted animals showed large, viable grafts containing TH-immunoreactive (ir) neurons. The density of TH-ir neurons in the human fetal xenografts and in rat fetal allografts was similar. A significant amelioration of the amphetamine-induced rotation was observed in the animals that received cultured tissue allografts. These results promote the feasibility of in vitro maintenance of fetal human and rat nigral tissue prior to transplantation using the free-floating roller tube technique.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Global complexity of 47-channel resting electroencephalogram (EEG) of healthy young volunteers was studied after intake of a single dose of a nootropic drug (piracetam, Nootropil® UCB Pharma) in 12 healthy volunteers. Four treatment levels were used: 2.4, 4.8, 9.6 g piracetam and placebo. Brain electric activity was assessed through Global Dimensional Complexity and Global Omega-Complexity as quantitative measures of the complexity of the trajectory of multichannel EEG in state space. After oral ingestion (1–1.5 h), both measures showed significant decreases from placebo to 2.4 g piracetam. In addition, Global Dimensional Complexity showed a significant return to placebo values at 9.6 g piracetam. The results indicate that a single dose of piracetam dose-dependently affects the spontaneous EEG in normal volunteers, showing effects at the lowest treatment level. The decreased EEG complexity is interpreted as increased cooperativity of brain functional processes.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Covert brain activity related to task-free, spontaneous (i.e. unrequested), emotional evaluation of human face images was analysed in 27-channel averaged event-related potential (ERP) map series recorded from 18 healthy subjects while observing random sequences of face images without further instructions. After recording, subjects self-rated each face image on a scale from “liked” to “disliked”. These ratings were used to dichotomize the face images into the affective evaluation categories of “liked” and “disliked” for each subject and the subjects into the affective attitudes of “philanthropists” and “misanthropists” (depending on their mean rating across images). Event-related map series were averaged for “liked” and “disliked” face images and for “philanthropists” and “misanthropists”. The spatial configuration (landscape) of the electric field maps was assessed numerically by the electric gravity center, a conservative estimate of the mean location of all intracerebral, active, electric sources. Differences in electric gravity center location indicate activity of different neuronal populations. The electric gravity center locations of all event-related maps were averaged over the entire stimulus-on time (450 ms). The mean electric gravity center for disliked faces was located (significant across subjects) more to the right and somewhat more posterior than for liked faces. Similar differences were found between the mean electric gravity centers of misanthropists (more right and posterior) and philanthropists. Our neurophysiological findings are in line with neuropsychological findings, revealing visual emotional processing to depend on affective evaluation category and affective attitude, and extending the conclusions to a paradigm without directed task.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Here, we review the effects of non-invasive brain stimulation such as transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) in the rehabilitation of neglect. We found 12 studies including 172 patients (10 TMS studies and 2 tDCS studies) fulfilling our search criteria. Activity of daily living measures such as the Barthel Index or, more specifically for neglect, the Catherine Bergego Scale were the outcome measure in three studies. Five studies were randomized controlled trials with a follow-up time after intervention of up to 6 weeks. One TMS study fulfilled criteria for Class I and one for Class III evidence. The studies are heterogeneous concerning their methodology, outcome measures, and stimulation parameters making firm comparisons and conclusions difficult. Overall, there are however promising results for theta-burst stimulation, suggesting that TMS is a powerful add-on therapy in the rehabilitation of neglect patients.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

C57BL/6, BALB/c, and CBA/Ca mouse strains with different MHC-I haplotypes were compared with respect to susceptibility to Neospora caninum infection. Groups of 5 mice received , , or tachyzoites of the NC-Liverpool isolate by intraperitoneal injection and were observed for disease symptoms. Humoral responses, splenocyte interferon-γ (IFN-γ) production, cerebral parasite loads, and histopathology were evaluated at human end points or the latest at 34 days postinfection (PI). The mortality rates in C57BL/6 mice were the highest, and relatively high levels of IgG1 antibodies were detected in those mice surviving till 34 days PI. In lymphocyte proliferation assays, spleen cells from C57BL6 mice stimulated with N. caninum antigen extract exhibited large variations in IFN-γ production. In BALB/c mice mortality was 0% at the lowest and 100% at the highest infection dose. Serologically they responded with high levels of both IgG2a and IgG1 subclasses, and lymphocyte proliferation assays of surviving mice yielded lower IFN-γ levels. CBA/Ca mice were the most resistant, with no animal succumbing to infection at a dose of and tachyzoites, but 100% mortality at tachyzoites. High IgG2a levels as well as increased IFN-γ in lymphocyte proliferation assays were measured in CBA/Ca mice infected with tachyzoites.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Human pluripotent stem cells are a powerful tool for modeling brain development and disease. The human cortex is composed of two major neuronal populations: projection neurons and local interneurons. Cortical interneurons comprise a diverse class of cell types expressing the neurotransmitter GABA. Dysfunction of cortical interneurons has been implicated in neuropsychiatric diseases, including schizophrenia, autism, and epilepsy. Here, we demonstrate the highly efficient derivation of human cortical interneurons in an NKX2.1::GFP human embryonic stem cell reporter line. Manipulating the timing of SHH activation yields three distinct GFP+ populations with specific transcriptional profiles, neurotransmitter phenotypes, and migratory behaviors. Further differentiation in a murine cortical environment yields parvalbumin- and somatostatin-expressing neurons that exhibit synaptic inputs and electrophysiological properties of cortical interneurons. Our study defines the signals sufficient for modeling human ventral forebrain development in vitro and lays the foundation for studying cortical interneuron involvement in human disease pathology.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Human rabies is rare in Western Europe. It is not easily recognized in the absence of a history of exposure. We describe the clinical course, diagnosis and follow-up of an imported human rabies case in Switzerland. The patient, a U.S. citizen, presented at an outpatient clinic in Iraq with pain in his right shoulder on July 5, 2012. On July 8 he was transferred to a hospital in the United Arab Emirates, where he exhibited progressive encephalitis with coma. On July 29, he was transferred to a hospital in Switzerland, where he died on July 31, 2012. The autopsy showed severe encephalitis. Rabies was diagnosed by the rapid fluorescent focus inhibition test (RFFIT) and confirmed by fluorescence antibody testing (FAT) in brain smears and immunohistochemistry on paraffin-embedded brain sections. The viral strain was characterized by RT-PCR followed by sequencing and phylogenetic analysis as an American bat rabies strain associated with Tadarida brasiliensis. Close contacts and exposed health care workers received postexposure prophylaxis (PEP).

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Among rodent models for brain tumors, the 9L gliosarcoma is one of the most widely used. Our 9L-European Synchrotron Radiation Facility (ESRF) model was developed from cells acquired at the Brookhaven National Laboratory (NY, USA) in 1997 and implanted in the right caudate nucleus of syngeneic Fisher rats. It has been largely used by the user community of the ESRF during the last decade, for imaging, radiotherapy, and chemotherapy, including innovative treatments based on particular irradiation techniques and/or use of new drugs. This work presents a detailed study of its characteristics, assessed by magnetic resonance imaging (MRI), histology, immunohistochemistry, and cytogenetic analysis. The data used for this work were from rats sampled in six experiments carried out over a 3-year period in our lab (total number of rats = 142). The 9L-ESRF tumors were induced by a stereotactic inoculation of 10(4) 9L cells in the right caudate nucleus of the brain. The assessment of vascular parameters was performed by MRI (blood volume fraction and vascular size index) and by immunostaining of vessels (rat endothelial cell antigen-1 and type IV collagen). Immunohistochemistry and regular histology were used to describe features such as tumor cell infiltration, necrosis area, nuclear pleomorphism, cellularity, mitotic characteristics, leukocytic infiltration, proliferation, and inflammation. Moreover, for each of the six experiments, the survival of the animals was assessed and related to the tumor growth observed by MRI or histology. Additionally, the cytogenetic status of the 9L cells used at ESRF lab was investigated by comparative genomics hybridization analysis. Finally, the response of the 9L-ESRF tumor to radiotherapy was estimated by plotting the survival curves after irradiation. The median survival time of 9L-ESRF tumor-bearing rats was highly reproducible (19-20 days). The 9L-ESRF tumors presented a quasi-exponential growth, were highly vascularized with a high cellular density and a high proliferative index, accompanied by signs of inflammatory responses. We also report an infiltrative pattern which is poorly observed on conventional 9 L tumor. The 9L-ESRF cells presented some cytogenetic specificities such as altered regions including CDK4, CDKN2A, CDKN2B, and MDM2 genes. Finally, the lifespan of 9L-ESRF tumor-bearing rats was enhanced up to 28, 35, and 45 days for single doses of 10, 20, and 2 × 20 Gy, respectively. First, this report describes an animal model that is used worldwide. Second, we describe few features typical of our model if compared to other 9L models worldwide. Altogether, the 9L-ESRF tumor model presents characteristics close to the human high-grade gliomas such as high proliferative capability, high vascularization and a high infiltrative pattern. Its response to radiotherapy demonstrates its potential as a tool for innovative radiotherapy protocols.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Computational network analysis provides new methods to analyze the human connectome. Brain structural networks can be characterized by global and local metrics that recently gave promising insights for diagnosis and further understanding of neurological, psychiatric and neurodegenerative disorders. In order to ensure the validity of results in clinical settings the precision and repeatability of the networks and the associated metrics must be evaluated. In the present study, nineteen healthy subjects underwent two consecutive measurements enabling us to test reproducibility of the brain network and its global and local metrics. As it is known that the network topology depends on the network density, the effects of setting a common density threshold for all networks were also assessed. Results showed good to excellent repeatability for global metrics, while for local metrics it was more variable and some metrics were found to have locally poor repeatability. Moreover, between subjects differences were slightly inflated when the density was not fixed. At the global level, these findings confirm previous results on the validity of global network metrics as clinical biomarkers. However, the new results in our work indicate that the remaining variability at the local level as well as the effect of methodological characteristics on the network topology should be considered in the analysis of brain structural networks and especially in networks comparisons.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Treatment of central nervous system (CNS) diseases is limited by the blood-brain barrier (BBB), a selective vascular interface restricting passage of most molecules from blood into brain. Specific transport systems have evolved allowing circulating polar molecules to cross the BBB and gain access to the brain parenchyma. However, to date, few ligands exploiting such systems have proven clinically viable in the setting of CNS diseases. We reasoned that combinatorial phage-display screenings in vivo would yield peptides capable of crossing the BBB and allow for the development of ligand-directed targeting strategies of the brain. Here we show the identification of a peptide mediating systemic targeting to the normal brain and to an orthotopic human glioma model. We demonstrate that this peptide functionally mimics iron through an allosteric mechanism and that a non-canonical association of (i) transferrin, (ii) the iron-mimic ligand motif, and (iii) transferrin receptor mediates binding and transport of particles across the BBB. We also show that in orthotopic human glioma xenografts, a combination of transferrin receptor over-expression plus extended vascular permeability and ligand retention result in remarkable brain tumor targeting. Moreover, such tumor targeting attributes enables Herpes simplex virus thymidine kinase-mediated gene therapy of intracranial tumors for molecular genetic imaging and suicide gene delivery with ganciclovir. Finally, we expand our data by analyzing a large panel of primary CNS tumors through comprehensive tissue microarrays. Together, our approach and results provide a translational avenue for the detection and treatment of brain tumors.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Our recent studies have shown that the FoxM1B transcription factor is overexpressed in human glioma tissues and that the level of its expression correlates directly with glioma grade. However, whether FoxM1B plays a role in the early development of glioma (i.e., in transformation) is unknown. In this study, we found that the FoxM1B molecule causes cellular transformation and tumor formation in normal human astrocytes (NHA) immortalized by p53 and pRB inhibition. Moreover, brain tumors that arose from intracranial injection of FoxM1B-expressing immortalized NHAs displayed glioblastoma multiforme (GBM) phenotypes, suggesting that FoxM1B overexpression in immortalized NHAs not only transforms the cells but also leads to GBM formation. Mechanistically, our results showed that overexpression of FoxM1B upregulated NEDD4-1, an E3 ligase that mediates the degradation and downregulation of phosphatase and tensin homologue (PTEN) in multiple cell lines. Decreased PTEN in turn resulted in the hyperactivation of Akt, which led to phosphorylation and cytoplasmic retention of FoxO3a. Blocking Akt activation with phosphoinositide 3-kinase/Akt inhibitors inhibited the FoxM1B-induced transformation of immortalized NHAs. Furthermore, overexpression of FoxM1B in immortalized NHAs increased the expression of survivin, cyclin D1, and cyclin E, which are important molecules for tumor growth. Collectively, these results indicate that overexpression of FoxM1B, in cooperation with p53 and pRB inhibition in NHA cells, promotes astrocyte transformation and GBM formation through multiple mechanisms.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

CYP4F (Cytochrome P4504F) enzymes metabolize endogenous molecules including leukotrienes, prostaglandins and arachidonic acid. The involvement of these endogenous compounds in inflammation has led to the hypothesis that changes in the inflamed tissue environment may affect the expression of CYP4Fs during the pro-inflammatory state, which in turn may modulate inflammatory conditions during the anti-inflammatory state. We demonstrated that inflamed tissues have different levels of CYP4F isoform expression profiles in a number of human samples when compared to the average population. The CYP4F isoform expression levels change with the degree of inflammation present in tissue. Further investigation in cell culture studies revealed that inflammatory cytokines, in particular TNF-α, play a role in regulating the expression of the CYP4F family. One of the isoforms, CYP4F11, had different characteristics than that of the other five CYP4F family members. CYP4F11 metabolizes xenobiotics while the other isoforms metabolize endogenous compounds with higher affinity. CYP4F11 also was expressed at high quantities in the brain, and was up-regulated by TNF-α, while the other isoforms were not expressed at high quantities in the brain and were down-regulated by TNF-α. We identified the AP-1 protein of the JNK pathway as the signaling protein that causes significant increase in CYP4F11 expression. Since TNF-α stimulation causes a simultaneous activation of both JNK pathway and NF-κB signaling, we investigated further the role that NF-κB plays on expression of the CYP4F11 gene. We concluded that although there is a significant increase in CYP4F11 expression in the presence of TNF-α, the activation of NF-κB signaling inhibits CYP4F11 expression in a time dependent manner. The expression of CYP4F11 is only significantly increased after 24 hours of treatment with TNF-α; at shorter time points NF-κB signaling overpowers the JNK pathway activation. We believe that these findings may in the future lead to improved drug design for modulating inflammation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The cytochromes P450 (P450) comprise a superfamily of hemoproteins that function in concert with NADPH-cytochrome P450 reductase (P450-reductase) to metabolize both endogenous and exogenous compounds. Many pharmacological agents undergo phase I metabolism by this P450 and P450-reductase monooxygenase system. Phase I metabolism ensures that these highly hydrophobic xenobiotics are made more hydrophilic, and hence easier to extrude from the body. While the majority of phase I metabolism occurs in the liver, metabolism in extrahepatic organ-systems like the intestine, kidney, and brain can have important roles in drug metabolism and/or efficacy. ^ While P450-mediated phase I metabolism has been well studied, investigators have only recently begun to elucidate what physiological roles P450 may have. One way to approach this question is to study P450s that are highly or specifically expressed in extrahepatic tissues. In this project I have studied the role of a recently cloned P450 family member, P450 2D18, that was previously shown to be expressed in the rat brain and kidney, but not in the liver. To this end, I have used the baculovirus expression system to over-express recombinant P450 2D18 and purified the functional enzyme using nickel and hydroxylapatite chromatography. SDS-PAGE analysis indicated that the enzyme was purified to electrophoretic homogeneity and Western analysis showed cross-reactivity with rabbit anti-human P450 2D6. Carbon monoxide difference spectra indicated that the purified protein contained no denatured P450 enzyme; this allowed for further characterization of the substrates and metabolites formed by P450 2D18-mediated metabolism. ^ Because P450 2D18 is expressed in brain, we characterized the activity toward several psychoactive drugs including the antidepressants imipramine and desipramine, and the anti-psychotic drugs chlorpromazine and haloperidol. P450 2D18 preferentially catalyzed the N-demethylation of imipramine, desipramine, and chlorpromazine. This is interesting given the fact that other P450 isoforms form multiple metabolites from such compounds. This limited metabolic profile might suggest that P450 2D18 has some unique function, or perhaps a role in endobiotic metabolism. ^ Further analysis of possible endogenous substrates for P450 2D18 led to the identification of dopamine and arachidonic acid as substrates. It was shown that P450 2D18 catalyzes the oxidation of dopamine to aminochrome, and that the enzyme binds dopamine with an apparent KS value of 678 μM, a value well within reported dopamine concentration in brain dopaminergic systems. Further, it was shown that P450 2D18 binds arachidonic acid with an apparent KS value of 148 μM, and catalyzes both the ω-hydroxylation and epoxygenation of arachidonic acid to metabolites that have been shown to have vasoactive properties in brain, kidney, and heart tissues. These data provide clues for endogenous roles of P450 within the brain, and possible involvement in the pathogenesis of Parkinson's disease. ^

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Since the first demonstration of how to simultaneously measure brain activity using functional magnetic resonance imaging (fMRI) on two subjects about 10 years ago, a new paradigm in neuroscience is emerging: measuring brain activity from two or more people simultaneously, termed "hyperscanning". The hyperscanning approach has the potential to reveal inter-personal brain mechanisms underlying interaction-mediated brain-to-brain coupling. These mechanisms are engaged during real social interactions, and cannot be captured using single-subject recordings. In particular, functional near-infrared imaging (fNIRI) hyperscanning is a promising new method, offering a cost-effective, easy to apply and reliable technology to measure inter-personal interactions in a natural context. In this short review we report on fNIRI hyperscanning studies published so far and summarize opportunities and challenges for future studies.