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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The physicochemical properties of water enable it to act as a solvent for electrolytes, and to influence the molecular configuration and hence the function--enzymatic in particular--of polypeptide chains in biological systems. The association of water with electrolytes determines the osmotic regulation of cell volume and allows the establishment of the transmembrane ion concentration gradients that underlie nerve excitation and impulse conduction. Fluid in the central nervous system is distributed in the intracellular and extracellular spaces (ICS, ECS) of the brain parenchyma, the cerebrospinal fluid, and the vascular compartment--the brain capillaries and small arteries and veins. Regulated exchange of fluid between these various compartments occurs at the blood-brain barrier (BBB), and at the ventricular ependyma and choroid plexus, and, on the brain surface, at the pia mater. The normal BBB is relatively permeable to water, but considerably less so to ions, including the principal electrolytes Brain fluid regulation takes place within the context of systemic fluid volume control, which depends on the mutual interaction of osmo-, volume-, and pressure-receptors in the hypothalamus, heart and kidney, hormones such as vasopressin, renin-angiotensin, aldosterone, atriopeptins, and digitalis-like immunoreactive substance, and their respective sites of action. Evidence for specific transport capabilities of the cerebral capillary endothelium, for example high Na+K(+)-ATPase activity and the presence at the abluminal surface of a Na(+)--H+ antiporter, suggests that cerebral microvessels play a more active part in brain volume regulation and ion homoeostasis than do capillaries in other vascular beds. The normal brain ECS amounts to 12-19% of brain volume, and is markedly reduced in anoxia, ischaemia, metabolic poisoning, spreading depression, and conventional procedures for histological fixation. The asymmetrical distributions of Na+ K+ and Ca2+ between ICS and ECS underlie the roles of these cations in nerve excitation and conduction, and in signal transduction. The relatively large volume of the CSF, and extensive diffusional exchange of many substances between brain ECS and CSF, augment the ion-homeostasing capacity of the ECS. The choroid plexus, in addition to secreting CSF principally by biochemical mechanisms (there is an additional small component from the extracellular fluid), actively transports some substances from the blood (e.g. nucleotides and ascorbic acid), and actively removes others from the CSF. In contrast with CSF secretion, CSF reabsorption is principally a biomechanical process, passively dependent on the CSF-dural sinus pressure gradient. Pathological increases in intracranial water content imply development of an intracranial mass lesion. The additional water may be distributed diffusely within the brain parenchyma as brain oedema, as a cyst, or as increase in ventricular volume due to hydrocephalus. Brain oedema is classified on the basis of pathophysiology into four categories, vasogenic, cytotoxic, osmotic and hydrostatic. The clinical conditions in which brain oedema presents the greatest problems are tumour, ischaemia, and head injury. Peritumoural oedema is predominantly vasogenic and related to BBB dysfunction. Ischaemic oedema is initially cytotoxic, with a shift of Na+ and CI- ions from ECS to ICS, followed by osmotically obliged water, this shift can be detected by diffusion-weighted MRI. Later in the evolution of an ischaemic lesion the oedema becomes vasogenic, with disruption of the BBB. Recent imaging studies in patients with head injury suggest that the development of traumatic brain oedema may follow a biphasic time course similar to that of ischaemic oedema. Hydrocephalus is associated in the great majority of cases with an obstruction to the circulation or drainage of CSF, or, occasionally, with overproduction of CSF by a choroid plexus papilloma. In either case, the consequence is a ris
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PMID:The normal and pathological physiology of brain water. 907 71

We report a patient with long-standing asymmetrical parkinsonism, cerebellar ataxia and dysautonomia, suggestive of multiple system atrophy (MSA). However, the patient also developed involuntary repetitive movements similar to ballic dyskinesias and mental deterioration. MRI revealed major involvement of both posterior fossa structures and basal ganglia. The case would be accommodated within a rubric of MSA widened to include involvement of the subthalamic nucleus and the medial part of the pallidum, pathology which may account for the ballic movements. Additionally the patient's cognitive and behavioural disturbances suggest an impairment of striato-prefrontal cortex loop.
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PMID:Hemiballism in a patient with probable multiple system atrophy. 912 23

Acute necrotizing encephalopathy (ANE) of childhood is a newly proposed disease entity characterized by symmetrically distributed necrotic brain lesions in the thalamus, cerebral white matter, brainstem, and cerebellum. We report a 4-year-old girl with severe psychomotor delay and horizontal gaze palsy as sequelae of ANE at 17 months of age. The computed tomography showed bilaterally symmetrical low density areas in the thalamus and low density areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. MRI (T 1-weighted) revealed unevenly distributed small low signal intensity areas with scattered high intensity regions in the thalamus bilaterally. The T2-weighted images showed multiple small low intensity areas around high intensity areas, and low signal intensity areas in the left middle cerebral artery (MCA) region and the posterior cerebral artery (PCA) region. In addition to severe psychomotor delay, the patient exhibited a peculiar eye movements. Horizontal ocular movement was impaired, but vertical ocular movement was almost completely normal. As clearly shown by MRI of the brain, the pontine tegmentum, including bilateral abducens nucleus, paramedian pontine reticular formation (PPRF), medial longitudinal fasciculus (MLF), and the facial nerve were affected, but the thalamo-mesencephalic junction, including the rostral interstitial medial longitudinal fasciculus (riMLF) and the nucleus of Cajal, was spared. To our knowledge, this is the first case of ANE associated with this selective ocular movement disorder ever reported. Because of the multiple symmetrical lesions and pons and the asymmetrical lesions of the MCA and PCA regions in the present case, occlusion of a single vessel could not account for the pathology. The pathophysiological mechanism of ANE is unknown. We postulate that some toxic or vasoactive agent caused vasospasm and subsequent breakdown of the blood-brain barrier, especially in the thalamus and pons, resulting in the unique distribution of the lesions and the rare eye movement disorder observed in the present case.
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PMID:[Acute necrotizing encephalopathy with horizontal gaze palsy]. 928 70

Using statistical parametric mapping and [11C]flumazenil (FMZ) PET we have previously shown reduction of central benzodiazepine receptor (cBZR) binding restricted to the hippocampus in mesial temporal lobe epilepsy due to unilateral hippocampal sclerosis. However, bilateral hippocampal pathology can be present in up to 50% of patients with mesial temporal lobe epilepsy. Additionally, the limited spatial resolution of PET results in a partial volume effect that affects quantitative analysis of cBZRs and such an effect can mask hippocampal dysfunction. We analysed changes in the [11C]FMZ volume of distribution (FMZ-Vd) before and after correction for partial volume effect in six patients with refractory mesial temporal lobe epilepsy and a quantitative MRI diagnosis of bilateral hippocampal sclerosis, which appeared either symmetrical on MRI (bilateral symmetrical hippocampal sclerosis; three patients) or bilateral but asymmetrical (asymmetrical hippocampal sclerosis; three patients), and in nine patients with refractory mesial temporal lobe epilepsy and unilateral hippocampal sclerosis on MRI than was subsequently histologically verified. Fifteen healthy controls were also studied for comparison. Before correction for partial volume effects, significant unilateral reductions of FMZ-Vd were found in one of the three patients with bilateral symmetrical hippocampal sclerosis, in one of the three asymmetrical hippocampal sclerosis patients and in six of the nine unilateral hippocampal sclerosis patients. No significant bilateral reductions of hippocampal FMZ-Vd were detected. After correction for partial volume effect, all three patients with bilateral symmetrical hippocampal sclerosis showed significant bilateral reductions of FMZ-Vd, and these were asymmetrical in two. All three patients with asymmetrical hippocampal sclerosis and all nine patients with unilateral hippocampal sclerosis on MRI showed unilateral reductions of FMZ-Vd concordant with the side of the EEG focus. In addition one of the three patients with asymmetrical hippocampal sclerosis and three of the nine patients with unilateral hippocampal sclerosis showed significant reductions of FMZ-Vd in the hippocampus contralateral to the side of the EEG focus. Absolute quantification of [11C]FMZ-PET, corrected for partial volume effect, within multiple hippocampal volumes of interest was necessary in order to detect bilateral changes of cBZR in mesial temporal lobe epilepsy due to hippocampal sclerosis with optimal sensitivity. This [11C]FMZ-PET approach was able to demonstrate subtle contralateral abnormalities in one-third of patients thought to have unilateral or bilateral asymmetrical hippocampal sclerosis on MRI. Reduction of cBZR binding was consistently over and above loss of hippocampal volume indicating that atrophy is not the sole determinant of cBZR loss in mesial temporal lobe epilepsy.
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PMID:Regional hippocampal [11C]flumazenil PET in temporal lobe epilepsy with unilateral and bilateral hippocampal sclerosis. 936 76

Two patients, a woman aged 21 and a man aged 29, with asymmetrical swellings of both mandibular angles and a painful, heavy sensation in the masticatory muscles (and in the woman also round the maxillary joint), were diagnosed as having hypertrophy of the masseter muscles. Both had the habit of jaw clenching and tooth grinding. Treatment consisted not of the traditional surgical debulking which also allows correction of overdeveloped osseous mandibular angles, but of injections with botulinum toxin type A. Injection of 40-60 IU (product: Botox) per muscle was followed by some atrophy; cosmetically satisfactory results were achieved after repetition of the treatment a few months later. Reduction of muscle volume was confirmed by a quantitative volumetric assessment of MRI scans. In the female patient, the pain also abated.
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PMID:[Botulinum toxin type A treatment of cosmetically disturbing masseteric hypertrophy]. 962 1

We measured visuomotor responses following the Poffenberger paradigm in an acallosal boy, without other detectable neural defects. In this task crossed and uncrossed RT reflect the time of intra- and interhemispheric integration and the difference (CUD) estimates the interhemispheric transfer time. CUDs in the hemifields were largely asymmetrical in this subject, suggesting that visuomotor processing is extremely lengthened when the right hemisphere (RH) detects the light and the left hemisphere (LH) controls the motor output whereas it is very fast in the opposite direction. This asymmetry, which is present in comparable data available from the literature, may indicate the functional superiority of the LH in controlling the ipsilateral hand, as suggested by recent MRI findings.
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PMID:Asymmetry of the interhemispheric visuomotor integration in callosal agenesis. 963 24

MRI was performed in 32 patients with motor neurone disease (26 men and 6 women, aged 40-77 years) and in a control group of 21 subjects. Of the patients studied, 19 had definite and 11 probable amyotrophic lateral sclerosis (ALS) and two had progressive bulbar palsy. In 10 patients there were asymmetrical bilateral foci of increased signal intensity on proton-density and T2-weighted images, confined to the white matter. Two patients had only cortical frontal atrophy and slightly increased ventricular size, whereas 20 had normal MRI. The focal lesions were not confined to corticospinal tracts, but were also observed in subcortical frontal areas. While the lesions along the corticospinal tracts correspond to pyramidal tract degeneration, the subcortical foci correlate with degeneration of the frontal bundles and indicate generalised involvement of the central nervous system.
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PMID:Subcortical frontal lesions on MRI in patients with motor neurone disease. 963 70

This two-part study reviews data from a recently developed colony of New Zealand white rabbits with familial, nonsyndromic unilateral coronal suture synostosis, and this second part presents neuropathological findings and age-related changes in intracranial volume (ICV) and intracranial pressure (ICP) in 106 normal rabbits and 56 craniosynostotic rabbits from this colony. Brain morphology and anteroposterior length were described in 44 rabbit fetuses and perinates (27 normal; 17 synostosed). Middle meningeal artery patterns were qualitatively assessed from 2-D PCC MRI VENC scans and endocranial tracings from 15, 126-day-old rabbits (8 normal, 7 rabbits with unicoronal synostosis). Brain metabolism was evaluated by assessing 18F-FDG uptake with high-resolution PET scanning in 7, 25-day-old rabbits (3 normal, 4 with unicoronal or bicoronal synostosis). Intracranial contents and ICV were assessed using 3-D CT scanning of the skulls of 30 rabbits (20 normal,10 with unicoronal synostosis) at 42 and 126 days of age. Serial ICP data were collected from 66 rabbits (49 normal; 17 with unicoronal synostosis) at 25 and 42 days of age. ICP was assessed in the epidural space using a Codman NeuroMonitor microsensor transducer. Results revealed that cerebral cortex morphology was similar between normal and synostosed fetuses around the time of synostosis. Significantly (P<0.05) decreased A-P cerebral hemisphere growth rates and asymmetrical cortical remodeling were noted with increasing age in synostotic rabbits. In addition, rabbits with unicoronal suture synostosis exhibited asymmetrical middle meningeal artery patterns, decreased and asymmetrical brain metabolism, a "beaten-copper" intracranial appearance, significantly (P<0.05) decreased ICV, and significantly (P<0.01) elevated ICP compared with normal control rabbits. The advantages and disadvantages of these rabbits as a model for human familial, nonsyndromic unicoronal suture synostosis are discussed, especially in light of recent clinical neuropathological, ICV, and ICP findings recorded in human craniosynostotic studies.
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PMID:A rabbit model of human familial, nonsyndromic unicoronal suture synostosis. II. Intracranial contents, intracranial volume, and intracranial pressure. 969 36

In order to study the functional anatomy of hemispheric dominance for language comprehension we compared the patterns of activations and deactivations with PET and H(2)15O during a story-listening task in two groups of normal volunteers selected on the basis of their handedness. The reference task was a silent rest. The results showed asymmetrical temporal activations favoring the left hemisphere in right handers (RH) together with Broca's area and medial frontal activations. A rightward lateralization of deactivations located in the parietal and inferior temporal gyrus was also observed. In left handers (LH) the temporal activations were more symmetrical as were the parietal and inferior frontal deactivations. Broca's area and medial frontal gyrus activations were present in LH. The direct comparison of RH and LH activations revealed larger activations in the left superior temporal, in particular in the left planum temporale and temporal pole of RH, while LH activated an additional right middle temporal region. Individual analysis of LH differences images superimposed on individual MRI planes demonstrated an important variability of functional dominance, with two LH leftward lateralized, two symmetrical, and one showing a rightward lateralization of temporal activations. There was no relationship between functional dominance and handedness scores. These results are in accordance with data from aphasiology that suggest a greater participation of the right hemisphere in language processing in LH. In addition, the presence of bilateral deactivations of the dorsal route could support the assumption that LH ambilaterality concerns, in addition to language, other cognitive functions such as visuospatial processing.
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PMID:Functional anatomy of dominance for speech comprehension in left handers vs right handers. 969 71

A positron emission tomography (PET) study on the regional cerebral glucose metabolism (rCMRglc) was performed in six patients with corticobasal degeneration (CBD). The clinical features included asymmetrical parkinsonism with apraxia, were related to the cerebral cortical and basal ganglionic dysfunction. An MRI study showed all cases to have asymmetrical atrophy in the front-parietal cortex contralateral to the dominantly affected limb; however, no case was pathologically verified. A PET study revealed three cases to have asymmetrical glucose hypometabolism in the parietal lobe and thalamus, which was compatible with the results of previous reports. However, two patients demonstrated symmetrical glucose hypometabolism in the frontal lobe, striatum and parietal lobe while one case had a diffuse hypometabolism, in spite of a marked asymmetry of the neurological findings. These results therefore suggest the heterogeneity of the glucose hypometabolism in CBD based on the PET findings.
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PMID:Heterogeneity of glucose metabolism in corticobasal degeneration. 987 84


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