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PubMed2000

Rat oligodendrocytes express the vitamin D(3) receptor and respond to 1,25-dihydroxyvitamin D(3).

The present study investigates the presence of vitamin D receptor (VDR) in cells of the rat oligodendrocyte (OL) lineage. VDR transcripts were detected by in situ hybridization in a fraction of rat OL in secondary cultures. The VDR protein was shown to be co-localized in cells that are also recognized by an anti-myelin basic protein (MBP) antibody. Likewise, in vivo, VDR-positive cells were found in the brain white matter, such as the internal capsule of the striatum or the corpus callosum but also in the spinal cord. At least part of these positive cells in vivo correspond to OL, since they were co-stained by an anti-carbonic anhydrase II antiserum. Northern blot analyses of the CG-4 OL cell line demonstrated that the VDR transcripts are already found in the O-2A precursors. There was a two-fold increase in the relative abundance of these transcripts in differentiated OL or in type-2 astrocytes. 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] increased the pool of transcripts encoding its own receptor, the VDR. The hormone also enhanced the abundance of the mRNA of the nerve growth factor (NGF) and of its low-affinity receptor, the p75(NTR) protein. By contrast, the hormone had no effect on the levels of MBP or proteolipid protein (PLP) mRNA. This finding suggests that unlike retinoic acid (RA) or thyroid hormone, 1,25-(OH)(2)D(3) has no regulatory action on the synthesis of myelin proteins.

Animals↗
PubMed2000

Prefrontal cortical projections to the striatum in macaque monkeys: evidence for an organization related to prefrontal networks.

The organization of projections from the prefrontal cortex (PFC) to the striatum in relation to previously defined "orbital" and "medial" networks within the PFC were studied in monkeys using anterograde and retrograde tracing techniques. The results indicate that the orbital and medial networks connect to different striatal regions. The ventromedial striatum (the medial caudate nucleus, accumbens nucleus, and ventral putamen) receives input predominantly from the medial PFC (mPFC) and orbital areas 12o, Iai, and 13a, which constitute the "medial" network. More specifically, caudal medial areas 32, 25, and 14r project to the medial edge of the caudate nucleus, accumbens nucleus, and ventromedial putamen, whereas rostral areas 10o, 10m, and 11m are restricted to the medial edge of the caudate. Projections from orbital areas 12o, 13a, and Iai extend more laterally into the lateral accumbens and the ventral putamen. Area 24 gives rise to a divided pattern of projections, including fibers to the ventromedial striatum, apparently from area 24b, and fibers to the dorsolateral striatum, apparently from area 24c. Other areas of orbital cortex (11l, 12m, 12l, 13m, 13l, Ial, and Iam) that constitute the "orbital" network project primarily to the central part of the rostral striatum. This region includes the central and lateral parts of the caudate nucleus, and the ventromedial putamen, on either side of the internal capsule. The results support the subdivision of the orbital and medial PFC into "medial" and "orbital" networks and suggest that the prefrontostriatal projections reflect the functional organization of the PFC rather than topographic location.

Animals↗
PubMed2000

Visualization of nerve fiber orientation in gross histological sections of the human brain.

Diffusion weighted magnetic resonance imaging (DWMRI) allows visualization of the orientation of the nervous fibers in the living brain. For comparison, a method was developed to examine the orientation of fibers in histological sections of the human brain. Serial sections through the entire human brain were analyzed regarding fiber orientation using polarized light. Direction of fibers in the cutting plane was obtained by measuring the azimuth with the lowest intensity value at each point, and inclination of fibers in the section was evaluated using fuzzy logic approximations. Direction and inclination of fibers revealing their three-dimensional orientation were visualized by colored arrows mapped into the images. Using this procedure, various fiber tracts were identified (pyramidal tract, radiatio optica, radiatio acustica, arcuate fascicle, and 11 more). Intermingled fibers could be separated from each other. The orientation of the fiber tracts derived from polarized light microscopy was validated by confocal laser scanning microscopy in a defined volume of the internal capsule, where the fiber orientation was studied in four human brains. The polarization method visualizes the high degree of intermingled fiber bundles in the brain, so that distinct fiber pathways cannot be understood as solid, compact tracts: Neighbouring bundles of fibers can belong to different systems of fibers distinguishable by their orientation.

Aged↗
PubMed2000

Multi-component apparent diffusion coefficients in human brain: relationship to spin-lattice relaxation.

In vivo measurements of the human brain tissue water signal decay with b-factor over an extended b-factor range up to 6,000 s/mm(2) reveal a nonmonoexponential decay behavior for both gray and white matter. Biexponential parametrization of the decay curves from cortical gray (CG) and white matter voxels from the internal capsule (IC) of healthy adult volunteers describes the decay process and serves to differentiate between these two tissues. Inversion recovery experiments performed in conjunction with the extended b-factor signal decay measurements are used to make separate measurements of the spin-lattice relaxation times of the fast and slow apparent diffusion coefficient (ADC) components. Differences between the spin-lattice relaxation times of the fast and slow ADC components were not statistically significant in either the CG or IC voxels. It is possible that the two ADC components observed from the extended b-factor measurements arise from two distinct water compartments with different intrinsic diffusion coefficients. If so, then the relaxation results are consistent with two possibilities. Either the spin-lattice relaxation times within the compartments are similar or the rate of water exchange between compartments is "fast" enough to ensure volume averaged T(1) relaxation yet "slow" enough to allow for the observation of biexponential ADC decay curves over an extended b-factor range. Magn Reson Med 44:292-300, 2000.

Adult↗
PubMed2000

Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis.

High-resolution diffusion tensor imaging (DTI) was performed in 14 patients with clinically definite multiple sclerosis (MS) and the trace of the diffusion tensor ( ) and the fractional anisotropy (FA) were determined in normal appearing white matter (NAWM) and in different types of focal MS lesions. A small but significant increase of the in NAWM compared to control white matter ((840 +/- 85) x 10(-6) mm(2)/sec vs. (812 +/- 59) x 10(-6) mm(2)/sec; P < 0.01) was found. In addition, there was a significant decrease in the FA of normal-appearing regions containing well-defined white matter tracts, such as the genu of the internal capsule. In non-acute lesions, the of T(1)-hypointense areas was significantly higher than that of T(1)-isointense lesions ((1198 +/- 248) x 10(-6) mm(2)/sec vs. (1006 +/- 142) x 10(-6) mm(2)/sec; P < 0. 001), and there was a corresponding inverse relation of FA. Diffusion characteristics of active lesions with different enhancement patterns were also significantly different. DTI with a phase navigated interleaved echo planar imaging technique may be used to detect abnormalities of isotropic and anisotropic diffusion in the NAWM and selected fiber tracts of patients with MS throughout the entire brain, and it demonstrates substantial differences between various types of focal lesions.

Adult↗
PubMed1999

Anatomic correlates of painful tonic spasms in multiple sclerosis.

Painful tonic spasms (PTS) are now regarded as a typical symptom of multiple sclerosis but pathologic or radiologic findings rarely have been described. We report clinical and magnetic resonance imaging records of five original cases. In all of them, lesions likely responsible for unilateral PTS involved the motor pathway at the level of the posterior limb of the internal capsule or the cerebral peduncle on the opposite side. Closeness of motor fibers seems to be the most important underlying anatomic factor because it enables involvement of a higher proportion of axons by a single demyelinating lesion and radial spread of ephaptic activation. In turn, preservation of the underlying pyramidal-spinal tract could make it easier for the pathologic discharge to reach the peripheral effectors and generate PTS.

Adult↗
PubMed1999

Hemichorea and hemiballism associated with contralateral hemiparesis and ipsilateral basal ganglia lesions.

We report on two patients with unilateral hyperkinetic movement disorders associated with contralateral hemiparesis and ipsilateral basal ganglia lesions. The first patient, a 47-year-old woman, had a low-grade astrocytoma located in the right basal ganglia extending into the subthalamic area and the cerebral peduncle. She presented with left hemiparesis, right hemichorea, and intermittent right-sided tremor at rest. The second patient, a 85-year-old woman, had hypertensive hemorrhage to the right posterior basal ganglia, the posterior limb of the internal capsule, the lateral thalamus, and the subthalamic region with accompanying intraventricular bleeding. She developed right-sided transient hemichorea-hemiballism. A videotape illustration of one of the patients is provided. The literature on the rare occurrence of ipsilateral hemichorea-hemiballism is discussed and possible pathomechanisms are reviewed. We postulate that hemiparesis contralateral to basal ganglia lesions might have a conditioning effect on the appearance of ipsilateral dyskinetic movement disorders.

Aged↗
PubMed1998

Cerebellum and the sensory guidance of movement.

By the end of the 19th century the locations of the primary visual and motor areas of the cerebral cortex were well recognized. At that time it was generally assumed that for the visual control of movement visual areas must be linked to motor areas by way of a series of cortico-cortical fibres. Subsequent experimental evidence showed clearly, however, that skilled visuomotor performance is still possible after complete disconnection of interhemispheric and intracortical fibre systems. Preservation of skilled visuomotor performance after such lesions has often been thought to be mediated by ipsilaterally descending motor pathways. However, the evidence indicates that there must also be subcortical pathways that link sensory to motor areas of the brain. One such pathway involves the cerebellum. There is a massive input from cortical and subcortical visual areas to the pontine nuclei. Cells in the pontine nuclei respond vigorously to appropriate visual targets and they distribute their axonal terminals bilaterally in the cerebellar cortex. A cortico-ponto-cerebellar circuit would have remained intact in all cases in the literature in which there was complete disconnection of cortico-cortical fibres between visual and motor cortex. Lesions of the cortical sensory areas that project to the pons or interruption of the fibres within the internal capsule or basis pedunculi, that link cortical sensory areas with the pontine nuclei, can severely impair the sensory guidance of movement. This paper reviews the evidence for sensory input to the cerebellum and the possible role of a cortico-ponto-cerebellar circuit in the sensory guidance of movement.

Animals↗
PubMed2005

Klinefelter's syndrome (XXY) as a genetic model for psychotic disorders.

Males with an extra-X chromosome (Klinefelter's syndrome) frequently, although not always, have an increased prevalence of psychiatric disturbances that range from attention deficit disorder in childhood to schizophrenia or severe affective disorders during adulthood. In addition, they frequently have characteristic verbal deficits. Thus, examining brain magnetic resonance imaging (MRI) scans of these individuals may yield clues to the influence of X chromosome genes on brain structural variation corresponding to psychiatric and cognitive disorders. Eleven adult XXY and 11 age matched XY male controls were examined with a structured psychiatric interview, battery of cognitive tests, and an MRI scan. Ten of eleven of the XXY men had some form of psychiatric disturbance, four of whom had auditory hallucinations compared with none of the XY controls. Significantly smaller frontal lobe, temporal lobe, and superior temporal gyrus (STG) cortical volumes were observed bilaterally in the XXY men. In addition, diffusion tensor imaging (DTI) of white matter integrity resulted in four regions of reduced fractional anisotropy (FA) in XXY men compared with controls, three in the left hemisphere, and one on the right. These correspond to the left posterior limb of the internal capsule, bilateral anterior cingulate, and left arcuate bundle. Specific cognitive deficits in executive functioning attributable to frontal lobe integrity and verbal comprehension were noted. Thus, excess expression of one or more X chromosome genes influences both gray and white matter development in frontal and temporal lobes, as well as white matter tracts leading to them, and may in this way contribute to the executive and language deficits observed in these adults. Future prospective studies are needed to determine which gene or genes are involved and whether their expression could be modified with appropriate treatments early in life. Brain expressed genes that are known to escape inactivation on extra-X chromosomes would be prime candidates.

Adult↗
PubMed2004

Localization of white matter volume increase in autism and developmental language disorder.

Increased brain volume in autism appears to be driven mainly by an unexplained white matter enlargement, and we have reported a similar phenomenon in developmental language disorder (DLD). Localization of this enlargement would strongly guide research into its cause, tissue basis, and functional implications. We utilized a white matter parcellation technique that divides cerebral white matter into an outer zone containing the radiate compartment and an inner zone containing sagittal and bridging system compartments. In both high-functioning autism and DLD, enlargement localized to the radiate white matter (all lobes in autism, all but parietal in DLD), whereas inner zone white matter compartments showed no volume differences from controls. Furthermore, in both autism and DLD, later or longer-myelinating regions showed greater volume increases over controls. Neither group showed cerebral cortex, corpus callosum, or internal capsule volume differences from control. Radiate white matter myelinates later than deep white matter; this pattern of enlargement thus is consistent with striking postnatal head circumference percentile increases reported in autism. These findings suggest an ongoing postnatal process in both autism and DLD that is probably intrinsic to white matter, that primarily affects intrahemispheric and corticocortical connections, and that places these two disorders on the same spectrum.

Autistic Disorder↗
PubMed2005

Predictors of outcome in perinatal arterial stroke: a population-based study.

Some infants with perinatal arterial ischemic stroke (PAS) experience development of cerebral palsy (CP), epilepsy, and cognitive impairment, whereas others have a normal outcome. Previous prognostic studies rarely have included all diagnosed cases of PAS within a population. Among 199,176 infants born within Kaiser Permanente from 1997 to 2002, we electronically identified head imaging reports and physician diagnoses suggesting stroke. The diagnosis of PAS was confirmed by review of brain imaging and medical records. Presentation of PAS was considered delayed if symptoms were only noted after 28 days. Outcomes were determined by chart review. Of 40 infants with PAS, 36 were observed over 12 months. Abnormal outcomes included CP (58%), epilepsy (39%), language delay (25%), and behavioral abnormalities (22%). A delayed presentation was associated with increased risk for CP (relative risk [RR], 2.2; 95% confidence interval [CI], 1.2-4.2). Radiological predictors of CP included large stroke size (RR, 2.0; 95% CI, 1.2-3.2) and injury to Broca's area (RR, 2.5; 95% CI, 1.3-5.0), internal capsule (RR, 2.2; 95% CI, 1.1-4.4), Wernicke's area (RR, 2.0; 95% CI, 1.1-3.8), or basal ganglia (RR, 1.9; 95% CI, 1.1-3.3). Among infants with PAS, specific radiological findings and a lack of symptoms in the newborn period are associated with increased risk for CP.

Arterial Occlusive Diseases↗
PubMed1979

Dysarthria--clumsy hand syndrome produced by capsular infarct.

A 64-year-old hypertensive man presented with the dysarthria--clumsy hand syndrome, manifested by dysarthria, dysphagia, central facial weakness, deviation of the tongue on protrusion, incoordination of the affected hand, and mild imbalance on walking. A computed tomograpphic scan demonstrated a resolving acute infarction in the vicinity of the genu of the internal capsule.

Deglutition Disorders↗
PubMed1983

Central pontine myelinolysis following rapid correction of hyponatremia.

Central pontine and extrapontine myelinolysis was experimentally produced in dogs by the rapid correction of severe, sustained, vasopressin-induced hyponatremia. Hyponatremia alone or slowly corrected hyponatremia did not produce the disease. Affected dogs showed rigid quadriparesis. The central pons, lateral aspects of the thalamus and adjacent internal capsules, deep layers of cerebral cortex and subjacent white matter, cerebellum, and other regions were symmetrically involved. Myelin and oligodendroglia were affected out of proportion to axons and neurons. Thus, the clinical features, the distribution of the lesions, and their histological features closely resemble the human disease. These experiments document an electrolyte manipulation that can cause permanent neuropathological lesions. Taken with the available clinical data on human patients, the experimental results indicate that human myelinolysis may be due to a rapid increase in serum sodium from previously low levels, and that rapid normalization of severe, sustained hyponatremia should therefore be avoided.

Animals↗
PubMed1983

A sibship with neuroaxonal dystrophy and renal tubular acidosis: a new syndrome?

The clinical and pathological features of three siblings from nonconsanguineous parents are described. Two of the children died at 6 1/2 and 7 months of age of a central nervous system disorder characterized by severe behavioral retardation, hypotonia, and pyramidal tract signs. The third child, now 8 years old, has global mental retardation, inability to talk, marked tremors, and gait disturbances. All children exhibited inability to concentrate or acidify the urine, with growth delay partially corrected in the living child by alkali therapy. Computed tomographic scans revealed hyperdense lesions in the thalamus of one of the siblings and more striking hyperdensity of the basal ganglia in the eldest child. Findings at postmortem examination in two children, and by renal and sural nerve biopsy in the third, include swollen axons in the internal capsule and peripheral nerves, and neurons with iron-staining deposits, gliosis, and macrophages containing lipofuscin pigments in the brain. The renal findings include material positive for periodic acid-Schiff and hyperdense granular deposits in renal tubules.

Acidosis, Renal Tubular↗
PubMed1985

Leukoencephalopathy in diffuse hemorrhagic cerebral amyloid angiopathy.

We have studied 12 patients with diffuse hemorrhagic cerebral amyloid angiopathy clinically and at postmortem examination. The brains in 8 patients had diffuse bilateral loss of myelin in the hemispheric white matter sparing the U fibers, corpus callosum, and internal capsules. The periventricular areas were predominantly affected. Microscopic examination of the white matter showed an association with subacute or chronic edematous lesions: spongiosis, swollen oligodendroglia, widening of the perivascular spaces with edema fluid or siderophages, hyalinization of the blood vessel walls, incomplete myelin loss, and astrocytic gliosis. Three of 8 autopsied patients had undergone computed tomographic examination, which showed bilateral hypodensity of the hemispheric white matter. The brains of 4 patients with illnesses of shorter duration showed only discrete but similar lesions in the centrum semiovale. These white matter changes are similar to those observed in Binswanger's subcortical encephalopathy. We suggest that a common mechanism of hypoperfusion of the distal white matter causes the leukoencephalopathy.

Aged↗
PubMed1987

Latencies of visually guided saccades in unilateral hemispheric cerebral lesions.

Latencies of lateral visually guided saccades were studied in 60 patients without hemianopia who had unilateral focal lesions clearly visible on computed tomographic (CT) scan that were variously located in both cerebral hemispheres. Significantly asymmetrical latencies were found in 29 patients whose lesions had damaged the deep and posterior frontal region near the corpus callosum and/or, just inferior to this region, the anterior part of the internal capsule. In the 31 other patients, including those with lesions of the frontal eye fields (FEF), latencies were not significantly asymmetrical and the lesions spared the entire region just described. These topographical features suggest that the asymmetry of latencies is due to damage in a certain portion of the efferent pathways descending from the FEF. A significant increase in bilateral latency was observed in most patients whose lesions had damaged the posterior part of the parietal cortex and/or the underlying white matter. The parietal lobe could therefore exert an excitatory bilateral action on the triggering of visually guided saccades, probably mediated via the superior colliculus. A significant decrease in the bilateral or ipsilateral latency was often found in patients whose lesions had damaged the FEF or the underlying white matter. The frontal lobe could therefore exert a predominantly inhibitory bilateral action on this triggering, probably also mediated via the superior colliculus. However, an increase in contralateral latency in some patients with subcortical frontal lesions indicates that the FEF also probably have an excitatory action. This action could be transmitted directly (or indirectly via the superior colliculus) to the reticular premotor structures by tracts decussating partly through the corpus callosum.

Adult↗
PubMed1988

Magnetic resonance imaging in amyotrophic lateral sclerosis.

Magnetic resonance imaging (MRI) was used in 5 patients with clinically definite amyotrophic lateral sclerosis to determine the frequency of central white matter abnormalities. Two patients had symmetrical areas of increased signal intensity seen on MRI extending from the cortex, through the corona radiata, posterior limb of the internal capsule, and cerebral peduncles into the pons. These MRI abnormalities presumably relate to the pathological changes observed by others in the central white matter of patients with amyotrophic lateral sclerosis.

Adult↗
PubMed1988

Subcortical neglect: neuropsychological, SPECT, and neuropathological correlations with anterior choroidal artery territory infarction.

In 2 patients with infarction in the territory of the right anterior choroidal artery, hemiparesis, hemihypesthesia (in 1), and hemianopia or superior quadrantanopia were associated with severe multimodal hemineglect, without anosognosia, disorientation, or asomatognosia. Single-photon emission tomography showed that marked hypoperfusion was not limited to the right posterior capsular region, but also involved the overlying parietal cortex, and to a lesser extent the frontal cortex. At autopsy in 1 patient, the infarct was nearly limited to the deep white matter of the temporal isthmus and the retrolenticular part of the internal capsule; only minute lesions were present in the globus pallidus, body of caudate, and amygdala. These findings are consistent with a disconnection phenomenon as the basis for subcortical neglect with ipsilateral deactivation of the parietofrontal cortex.

Aged↗