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Subcortical White Matter (subcortical + white_matter)
Selected AbstractsActivation and deactivation of periventricular white matter phagocytes during postnatal mouse developmentGLIA, Issue 1 2010Mariya Hristova Abstract Brain microglia are related to peripheral macrophages but undergo a highly specific process of regional maturation and differentiation inside the brain. Here, we examined this deactivation and morphological differentiation in cerebral cortex and periventricular subcortical white matter, the main "fountain of microglia" site, during postnatal mouse development, 0,28 days after birth (P0,P28). Only macrophages in subcortical white matter but not cortical microglia exhibited strong expression of typical activation markers alpha5, alpha6, alphaM, alphaX, and beta2 integrin subunits and B7.2 at any postnatal time point studied. White matter phagocyte activation was maximal at P0, decreased linearly over P3 and P7 and disappeared at P10. P7 white matter phagocytes also expressed high levels of IGF1 and MCSF, but not TNFalpha mRNA; this expression disappeared at P14. This process of deactivation followed the presence of ingested phagocytic material but correlated only moderately with ramification, and not with the extent of TUNEL+ death in neighboring cells, their ingestion or microglial proliferation. Intravenous fluosphere labeling revealed postnatal recruitment and transformation of circulating leukocytes into meningeal and perivascular macrophages as well as into ramified cortical microglia, but bypassing the white matter areas. In conclusion, this study describes strong and selective activation of postnatally resident phagocytes in the P0,P7 subcortical white matter, roughly equivalent to mid 3rd trimester human fetal development. This presence of highly active and IGF1- and MCSF-expressing phagocytes in the neighborhood of vulnerable white matter could play an important role in the genesis of or protection against axonal damage in the fetus and premature neonate. © 2009 Wiley-Liss, Inc. [source] An FGF-responsive astrocyte precursor isolated from the neonatal forebrainGLIA, Issue 6 2009Grace Lin Abstract Gliogenesis in the mammalian CNS continues after birth, with astrocytes being generated well into the first two postnatal weeks. In this study, we have isolated an A2B5+ astrocyte precursor (APC) from the postnatal rat forebrain, which is capable of differentiating into mature astrocytes in serum-free medium without further trophic support. Exposure to basic fibroblast growth factor (bFGF) selectively induces the APCs to proliferate, forming clusters of vimentin+ cells, which, within 2 weeks, differentiate into GFAP+ astrocytes. While bFGF functions as a potent mitogen, neither is it necessary to induce or maintain astrocyte differentiation, nor is it capable of maintaining the precursors in an immature, proliferative state. APCs exit the cell cycle and differentiate, even in the continued presence of fibroblast growth factor alone or in combination with other mitogenic factors such as platelet-derived growth factor. Under the culture conditions used, it was not possible to cause the astrocytes to re-enter cell cycle. After transplantation into the neonatal forebrain, APCs differentiated exclusively into astrocytes, regardless of brain region. Initially distributed widely within the forebrain, the precursors are most greatly concentrated within the subventricular zone (SVZ) and subcortical white matter, where they are maintained throughout postnatal development. APCs can be isolated from the SVZ and white matter of animals as late as 4 weeks after birth. © 2008 Wiley-Liss, Inc. [source] The diagnostic utility of FLAIR imaging in clinically verified amyotrophic lateral sclerosisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2003Lijuan Zhang MD Abstract Purpose To explore the overall diagnostic ability of magnetic resonance (MR) fluid-attenuated inversion recovery (FLAIR) imaging for clinically verified amyotrophic lateral sclerosis (ALS). Materials and Methods Abnormal signal intensity in FLAIR images of 18 patients with ALS and 18 age-matched normal controls were scored and compared. Six patients had serial MR imaging scans within 97 days. Mann Whitney U statistics and ANOVA were used for statistical analysis. Results Hyperintensity in the subcortical white matter (SWM) and the dark line along the posterior rim of the precentral gyri were found more frequently in patients with ALS. The scores for these two signs were significantly different from those of normal controls. Hyperintensity in the corticospinal tract (CST) was found in both ALS and normal controls, but the difference was not statistically significant. ANOVA on the serial FLAIR studies revealed no significant difference in the scores among the series. The hyperintensity in SWM had a sensitivity of 56% and specificity of 94%, while the dark line in the motor cortex had a 74% sensitivity and 67% specificity. Conclusion Hyperintensity in SWM and the dark line along the posterior rim of the precentral gyri appeared more frequently in the patients with ALS. SWM hyperintensity has a better specificity in association with clinically verified ALS, while the motor dark line has a better sensitivity. No correlation was found between the FLAIR findings and progression of the disease. J. Magn. Reson. Imaging 2003;17:521,527. © 2003 Wiley-Liss, Inc. [source] Up-regulation of cerebral carbonic anhydrase by anoxic stress in pigletsJOURNAL OF NEUROCHEMISTRY, Issue 4 2003Antal Nógrádi Abstract The resuscitation of asphyxiated babies is associated with changes in cerebral protein synthesis that can influence the neurological outcome. Insufficient gas exchange results in rapid shifts in extracellular and intracellular pH. Carbonic anhydrase (CA) plays an important role in buffering acute changes in pH in the brain. We investigated whether asphyxia/re-ventilation influences the expression of cerebral CA isoforms (CA-II, CA-III and CA-IV) in anaesthetized newborn pigs. The cerebral cortex, hippocampus, cerebellum and retina were sampled, and prepared for either CA immunohistochemistry or CA immunoblotting from piglets subjected to asphyxia (10 min) followed by 2,4 h of re-ventilation, and also from normoxic controls. The CA immunoreactivity (IR) of all the isoforms studied was weak in the controls, apart from staining of a few oligodendrocytes in the subcortical white matter, some astrocytes in the superficial layer of the cerebral cortex, the cerebellar Purkinje cells and the retinal Müller cells that possessed moderate CA-II IR. However, asphyxia induced a marked increase in the CA IR of all isoforms in all the cerebral regions investigated and the retina after 4 h of survival. The pyramidal cells of the frontal cortex and hippocampus displayed the most conspicuous increase in CA IR. Immunoblotting confirmed increased levels of all the CA isoenzymes. We conclude that raised CA levels after asphyxia may contribute to the compensatory mechanisms that protect against the pathological changes in the neonatal CNS. [source] The Effect of Betamethasone Treatment on Neuroactive Steroid Synthesis in a Foetal Guinea Pig Model of Growth RestrictionJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2010A. A. McKendry There are ongoing concerns that antenatal corticosteroids, which are administered to women at high risk of delivering preterm to reduce the incidence of respiratory distress syndrome, have adverse effects on foetal brain development and subsequent effects on behaviour and learning, when administered as repeated courses. The present study aimed to examine whether repeated betamethasone treatment alters the expression of the key-rate limiting enzyme, 5,-reductase, in the synthetic pathway of the potent neuroactive steroid allopregnanolone in the brain and placenta and whether this effect is potentiated in growth restricted foetuses. To investigate this, pregnant guinea pigs carrying either control (sham surgery) or growth-restricted foetuses were treated with vehicle or betamethasone (1 mg/kg/day) for 4 days prior to sacrifice (65d). Placental insufficiency was induced by the ablation of uterine artery branches supplying each placenta at mid gestation, resulting in foetal growth restriction characterised by ,brain sparing'. Real-time reverse transcriptase polymerase chain reaction was used to determine relative 5,-reductase type 1 and 2 mRNA expression in the placenta and brain. Immunohistochemistry was used to examine the glial fibrillary acidic protein (GFAP) expression in the subcortical white matter, CA1 and dentate regions of the hippocampus. 5,-reductase type 2 mRNA expression in the brain was markedly reduced by betamethasone treatment in male foetuses compared to vehicle-treated controls but not in female foetuses. In addition, 5,-reductase type 1 expression in the brain was increased by growth restriction and/or betamethasone treatment in female foetuses but expression in males foetuses did not increase. 5,-reductase type 2 expression in the placenta was markedly reduced by betamethasone treatment compared to vehicle-treated control. Intrauterine growth restriction and betamethasone treatment reduced GFAP expression in the CA1 region of the hippocampus in the brains of male but not female foetuses. These data indicate that betamethasone treatment suppresses placental expression and has sexually dimorphic effects on expression of neuroactive steroid synthetic enzymes in the brain. These actions may lead to adverse effects on the developing brain, particularly in male foetuses, such as the observed effects on GFAP expression. [source] Neuroplastic Changes in the Brain: A Case of Two Successive Adaptive Changes Within the Motor CortexJOURNAL OF NEUROIMAGING, Issue 3 2010Eytan Raz MD ABSTRACT We describe a case of neuroplasticity associated with both arteriovenous malformation (AVM) and stroke, which occurred in two successive events in the same patient. Functional magnetic resonance imaging (fMRI) during right-hand movement in a young man with a left rolandic AVM detected activation of a region corresponding to the left premotor cortex. The AVM was embolized. A few hours after the last embolization session, the patient sustained an ischemic complication in the left subcortical white matter. A second fMRI detected a lower degree of left premotor cortex activation and strong activation of the contralesional right primary motor cortex and bilateral supplementary motor areas. One month later, in association with clinical recovery, the fMRI activation returned to that observed in the first fMRI, ie, selective activation of the ipsilesional left premotor cortex. This is, to our knowledge, the first description of two distinct functional cortical changes determined by an AVM and a stroke within the motor network. [source] Cerebral Embolism of Iodized Oil (Lipiodol) after Transcatheter Arterial Chemoembolization for Hepatocellular CarcinomaJOURNAL OF NEUROIMAGING, Issue 4 2009Joon-Tae Kim MD ABSTRACT Cerebral lipiodol embolism is a rare complication of transcatheter arterial chemoembolization (TACE). Its pathological mechanism remains ambiguous despite several investigations. In Case 1, a 67-year-old man with hepatocellular carcinoma (HCC) experienced neurological deficits soon after undergoing a fourth session of TACE. Computed tomography (CT) scan showed multiple hyperdense lesions along the gyrus of frontal lobes and in the subcortical white matter. Transcranial Doppler (TCD) and transesophageal echocardiogram performed during the intravenous injection of agitated saline documented the presence of a right-to-left shunt (RLS) by demonstrating microbubbles in the left middle cerebral artery and left atrium. In Case 2, a 63-year-old woman underwent a third TACE due to a large HCC. After the procedure, her mental status deteriorated. Brain CT showed multiple hyperdense lesions on the cerebral and cerebellar cortex. TCD with agitated saline showed multiple microembolic signals shortly after the injection of agitated saline. The risk of cerebral lipiodol embolism may increase with recurrence and progression of HCC in patients who have a pre-existing RLS in the heart or lung. A test for the detection of an RLS may be necessary to identify patients with a heightened risk of cerebral embolism when multiple TACE procedures are required. TACE for HCC can cause pulmonary embolism or infarction.1,2 However, cerebral lipiodol embolism is rare after TACE. There have been several reports of cerebral embolism after TACE, but their exact mechanism has not yet been fully elucidated. We report herein 2 patients who developed cerebral lipiodol embolism after undergoing multiple TACE procedures for remnant HCC through a pre-existing RLS. [source] Isolated Pontine Progressive Multifocal Leukoencephalopathy: Unusual Magnetic Resonance Imaging FeaturesJOURNAL OF NEUROIMAGING, Issue 1 2002Devon I. Rubin MD Progressive multifocal leukoencephalopathy (PML) is an uncommon opportunistic infection that causes focal or multifocal demyelination predominantly in the subcortical white matter. The authors describe the clinical and radiographic features in 2 unusual cases of PML that were initially isolated to the pons. One patient presented clinically with only an isolated sixth cranial nerve palsy. [source] Clinical and Magnetic Resonance Imaging Regression of Progressive Multifocal Leukoencephalopathy in an AIDS Patient After Intensive Antiretroviral TherapyJOURNAL OF NEUROIMAGING, Issue 3 2001Rita A. Shapiro DO ABSTRACT A 36-year-old homosexual man with 6 months of visual symptoms and headaches had right homonymous hemianopia, mild new learning impairment, and alexia with agraphia. The initial brain magnetic resonance imaging (MRI) scan was reported consistent with left occipital infarction. Subsequent MRI demonstrated abnormal demyelination in the subcortical white matter and deep parieto-occipital white matter bilaterally, but primarily left. Human immunodeficiency virus testing and cerebrospinal fluid polymerase chain reaction for JC virus DNA were both positive, consistent with progressive multifocal leukoencephalopathy (PML) with AIDS. His clinical status steadily deteriorated, and MRI white matter abnormalities worsened despite high-dose antiretroviral therapy. After the antiretroviral regimen was intensified by the addition of a protease inhibitor, rapid clinical and radiographic improvement occurred with subsequent MRI studies revealing only residual left parieto-occipital encephalomalacia. PML in AIDS patients has been associated with a nearly uniformly poor prognosis until recent reports of improved outcomes after highly active antiretroviral therapy. This patient with PML and AIDS similarly showed a robust clinical and MRI response to intensive antiretroviral combination therapy, which has been maintained for more than 3 years. [source] High-resolution isotropic 3D diffusion tensor imaging of the human brainMAGNETIC RESONANCE IN MEDICINE, Issue 5 2002Xavier Golay Abstract High-resolution cardiac-gated 3D diffusion tensor imaging (3D-DTI) is demonstrated in vivo for several areas of the human brain. Anatomical mapping of subcortical white matter (WM), as well as definition and identification of major WM bundles from the brainstem were performed in humans for the first time using this technique. Improved intrinsic signal-to-noise ratio (SNR) and relatively reduced sensitivity to physiological motion (e.g., brain pulsations) with respect to cardiac-gated multislice acquisition are demonstrated. The advantages and weaknesses of this approach are discussed. Magn Reson Med 47:837,843, 2002. © 2002 Wiley-Liss, Inc. [source] Effects of Betamethasone Treatment on Central Myelination in Fetal Sheep: An Electron Microscopical StudyANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2008C. Raschke Summary The long-term effect of betamethasone on the myelination of commissural and associational fibres was investigated in fetal sheep. We studied the corpus callosum and subcortical white matter by electron microscopy. Axons were subdivided into classes according to their axonal diameter: class I: ,0.65 ,m; class II: 0.66,0.84 ,m; class III: ,0.85 ,m. Under control conditions, the different functions of the white matter tracts examined were reflected by three morphological criteria: (1) there was a diverse percentage of axonal classes in the investigated areas. In corpus callosum the axons of class II predominate (47.1%). In the subcortical white matter, class I axons with small diameter are in majority (40.8%). (2) In the subcortical white matter more axons are present, with especially large diameter and hence of axonal class III. (3) The axons of subcortical white matter have thicker myelin sheaths than those of the corpus callosum. Betamethasone administration caused a significant decrease of class II axons in the corpus callosum (36.9%). In corpus callosum, axons of all classes present thicker myelin sheaths. Betamethasone administration resulted in a change in the formation of the myelin sheath in the commissural fibres of the corpus callosum but not in the associational fibres of the subcortical white matter. This could be the morphological correlate to behavioral and cognitive changes known to occur in humans after prenatal glucocorticoid treatment. [source] A disconnection account of Gerstmann syndrome: Functional neuroanatomy evidence,ANNALS OF NEUROLOGY, Issue 5 2009Elena Rusconi PhD Objective To examine the functional neuroanatomy that could account for pure Gerstmann syndrome, which is the selective association of acalculia, finger agnosia, left-right disorientation, and agraphia. Methods We used structural and functional neuroimaging at high spatial resolution in healthy subjects to seek a shared cortical substrate of the Grundstörung posited by Gerstmann, ie, a common functional denominator accounting for this clinical tetrad. We construed a functional activation paradigm that mirrors each of the four clinical deficits in Gerstmann syndrome and determined cortical activation patterns. We then applied fiber tracking to diffusion tensor images and used cortical activation foci in the four functional domains as seed regions. Results None of the subjects showed parietal overlap of cortical activation patterns from the four cognitive domains. In every subject, however, the parietal activation patterns across all four domains consistently connected to a small region of subcortical parietal white matter at a location that is congruent with the lesion in a well-documented case of pure Gerstmann syndrome. Interpretation Our functional neuroimaging findings are not in agreement with Gerstmann's postulate of damage to a common cognitive function underpinning clinical semiology. Our evidence from intact functional neuroanatomy suggests that pure forms of Gerstmann's tetrad do not arise from lesion to a shared cortical substrate but from intraparietal disconnection after damage to a focal region of subcortical white matter. Ann Neurol 2009;66:654,662 [source] Primary central nervous system post-transplantation lymphoproliferative disorder,CANCER, Issue 4 2010An International Primary Central Nervous System Lymphoma Collaborative Group Report Abstract BACKGROUND: Primary central nervous system (CNS) post-transplantation lymphoproliferative disorder (PCNS-PTLD) is a rare complication of solid organ transplantation. The objectives of this study were to define the clinical, radiologic, and pathologic features of this disease and to explore the impact of treatment on patient outcomes. METHODS: The authors reviewed the databases of participating institutions of the International Primary CNS Lymphoma Collaborative Group for cases of PCNS-PTLD. Thirty-four patients who had pathologically confirmed PCNS-PTLD without evidence of systemic PTLD were investigated retrospectively. RESULTS: The median time from transplantation to diagnosis of PCNS-PTLD was 4.4 years. Disease usually was multifocal and involved any location of the brain but was most common in the cerebral hemispheres, usually in the subcortical white matter or basal ganglia. Radiographically, all lesions enhanced either homogenously or in a ring-enhancing pattern. Cerebral biopsy was required to establish diagnosis in most patients. Most patients had monomorphic, Epstein-Barr virus (EBV)-positive disease of B-cell origin. Response rates were high regardless of treatment type, and the median survival was 47 months. Age was the only factor predictive of survival. CONCLUSIONS: The current study demonstrated that PCNS-PTLD is typically an EBV-induced B-cell lymphoma that is responsive to treatment with favorable survival in many patients. An aggressive approach to tissue confirmation of diagnosis and treatment with chemotherapy or radiotherapy should be strongly considered. Cancer 2010. © 2010 American Cancer Society [source] Subacute sclerosing panencephalitis: Relationship between clinical stage and diffusion-weighted imaging findingsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2006Alpay Alkan MD Abstract Purpose To investigate the relationship between clinical stages and apparent diffusion coefficient (ADC) changes in the brain of patients with subacute sclerosing panencephalitis (SSPE). Materials and Methods A total of 18 patients with stage II (N = 11) and III (N = 7) SSPE and 11 age-matched controls underwent routine MRI and diffusion-weighted imaging (DWI). The ADC values were automatically calculated. Seven distinct neuroanatomic structures (frontal, parieto-occipital, and cerebellar white matter; deep white matter; thalamus; basal ganglia; and brainstem) were selected for analysis in the patient and control groups. Results Hyperintensities in the periventricular and subcortical white matters on T2-weighted images and ADC maps were detected in 63.6% of patients with stage II and in all patients with stage III. There were significant differences between stage II and III patients and also between patients and control group in ADC values that obtained from all locations. The highest mean ADC values were calculated in stage III patients. Although MRI and DWI findings were normal in four patients with stage II disease, ADC values were significantly increased when compared with controls. Conclusion The stage of disorder may be independent of DWI appearance during the early stage (stages I and II), even though the brain is affected. Therefore, DWI and ADC values supplemental to routine MRI should also be utilized for lesion detection and definition to enhance diagnostic accuracy in patients with SSPE. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||