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Query: UMLS:C0917798 (cerebral ischemia)
 17,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

31P, 1H and lactate spectroscopic imaging was used to evaluate' the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (37.5 degrees C) or hypothermic (32 degrees C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 +/- 26 and 40 +/- 14 mm3 in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals.
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PMID:Effect of temperature in focal ischemia of rat brain studied by 31P and 1H spectroscopic imaging. 905 23

MR spectroscopy(MRS) is a powerful method to evaluate brain metabolism directly and non-invasively. We developed 3D-CSI method as a multi-voxel MRS. It has some advantages or single-voxel MRS; 1) spectra in many voxels can be acquired simultaneously 2) Mapping of metabolites can be acquired 3) A small size voxel can be obtained. It make it possible to evaluate the change of NAA in wide area. In case of cerebral ischemia, we found the tendency that NAA decreases in fatal damage area and is normal in recoverable damage area. Therefore, we suppose that NAA could be a indicator of viability of neuron. It is necessary to coordinate the data from MRI/ MRS and PET/SPECT for analyzing the pathophysiology of cerebral ischemia.
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PMID:[Evaluation of cerebral ischemia with metabolic image by using 3D-CSI--comparing with SPECT and PET]. 923 23

Combined NMR imaging and spectroscopy have been applied to mouse brain during focal cerebral ischemia. The present study evaluated the feasibility of NMR measurements on mice in order to fine-tune the sequences and experimental setup for systematic investigations on stroke including future studies on transgenic animals. The acquisition of high quality diffusion-weighted, perfusion-weighted, and T2-weighted images (DWI, PWI, T2-WI, respectively) is demonstrated and complemented by measurements of 1H volume-selective spectroscopy and spectroscopic imaging (SI). Despite the small volume of the mouse brain, a satisfactory signal-to-noise ratio can be achieved with reasonably short measurement times. C57black/6J mice with an average body weight of 25 g were studied using state-of-the-art NMR sequences at 4.7 T. After induction of focal cerebral ischemia, the lesion was found clearly distinguishable in all imaging techniques. The apparent diffusion coefficient (ADC) was reduced in the ischemic region, and an expansion of the affected volume was observed with ongoing ischemia time. In the H spectra of ischemic animals a distinct change in the concentrations of NAA and lactate was visible. This is the first report on both SI data and perfusion-weighted imaging on mouse brain. It is demonstrated that the perfusion deficit during ischemia can be well demarcated. The spatial resolution of changes in metabolite concentrations allows the clear differentiation of elevated lactate levels in ischemic brain tissue.
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PMID:High resolution MRI and MRS: a feasibility study for the investigation of focal cerebral ischemia in mice. 1022 85

Using different models of focal cerebral ischemia, the temporal and spatial rules of metabolism and energy changes in the post-ischemia brain tissue were measured by proton magnetic resonance spectroscopy (1HMRS) to provide valuable information for judging the prognosis of acute focal cerebral ischemia and carrying out effective therapy. Nine healthy Sprague-Dawly rats (both sexes) were randomly divided into two groups: The rats in the group A (n = 4) were occluded with self-thrombus for 1 h; The rats in the group B (n = 5) were occluded with thread-emboli for 1 h. The 1H MRS at 30, 40, 50, 60 min respectively was examined and the metabolic changes of NAA, Cho and Lac in the regions of interest were semiquantitatively analyzed. The spectrum integral calculus area ratio of NAA, Cho, Lac to Pcr + Cr was set as the criterion. The values of NAA.Cho in the regions of interest were declined gradually within 1 h after ischemia, especially, the ratio of Cho/(Pcr + Cr), NAA/(Pcr + Cr) at 60 min had significant difference with that at 50 min (P < 0.05). The ratio of Lac/(Pcr + Cr) began to decrease at 40 min from initial increase of Lac in both A and B groups. MR proton spectrum analysis was a non-invasive, direct and comprehensive tool for the study of cellular metabolism and the status of the biochemical energy in acute ischemia stroke.
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PMID:An experimental proton magnetic resonance spectroscopy analysis on early stage of acute focal cerebral ischemia. 1267 80

Diffusion-weighted Imaging (DWI) is a advantageous method for early detection of cerebral ischemia. DWI with echo-planar sequence (EP-DWI) offers multisectional images sensitive to cytotoxic edema in a very short aquisition time and is almost free from motion artifact. However, the susceptibility artifacts and low spatial resolution of EP-DWI must be improved. In estimation of DWI, influence of T2 must be considered, because DWI is almost always based on T2-weighted imaging. DWI is applied to other cerebral disorders such as degenerative and demyelinating disease, infectious disease, tumors or so. In order to demonstrate water diffusion precisely, diffusion tensor imaging (DTI) must be introduced and applied to anisotropy indices such as fractional anisotropy (FA) and depiction of neurofiber direction, tractography. Measurements of FA in various degenerative diseases may contribute to differentiation in normal appearing white matter. Diffusion tensor tractography may provide more information about relationship of major white matter tract such as corticospinal tract with brain lesion. Furthermore, DWI and DTI are expected to demonstrate diffusion of protons of aminoacids such as choline, creatine, NAA and provide more pertinent information of regional pathologic state of the brain in future.
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PMID:[Principles of diffusion-weighted MR imaging and application to clinical neurology]. 1565 42

The aim of the present study was to identify the distinguishing metabolic characteristics of brain tissue salvaged by reperfusion following focal cerebral ischemia. Rats were subjected to 120 min of middle cerebral artery occlusion followed by 120 min of reperfusion. The rats received an intravenous bolus injection of [1-(13)C]glucose plus [1,2-(13)C]acetate. Subsequently two brain regions considered to represent penumbra and ischemic core, i.e. the frontoparietal cortex and the lateral caudoputamen plus lower parietal cortex, respectively, were analyzed with (13)C NMRS and HPLC. The results demonstrated four metabolic events that distinguished the reperfused penumbra from the ischemic core. (1) Improved astrocytic metabolism demonstrated by increased amounts of [4,5-(13)C]glutamine and improved acetate oxidation. (2) Neuronal mitochondrial activity was better preserved although the flux of glucose via pyruvate dehydrogenase into the tricarboxylic acid (TCA) cycle in glutamatergic and GABAergic neurons was halved. However, NAA content was at control level. (3) Glutamatergic and GABAergic neurons used relatively more astrocytic metabolites derived from the pyruvate carboxylase pathway. (4) Lactate synthesis was not increased despite decreased glucose metabolism in the TCA cycle via pyruvate dehydrogenase. In the ischemic core both neuronal and astrocytic TCA cycle activity declined significantly despite reperfusion. The utilization of astrocytic precursors originating from the pyruvate carboxylase pathway was markedly reduced compared the pyruvate dehydrogenase pathway in glutamate, and completely stopped in GABA. The NAA level fell significantly and lactate accumulated. The results demonstrate that preservation of astrocytic metabolism is essential for neuronal survival and a predictor for recovery.
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PMID:Glutamate and GABA metabolism in transient and permanent middle cerebral artery occlusion in rat: importance of astrocytes for neuronal survival. 1650 42

The magnitude of the motor deficit in patients with stroke depends not only on the size and location of the destroyed brain tissue, but also on axonal injury in the descending motor pathways which appears after stroke. After cerebral ischemia, there are no visible abnormalities in conventional MRI in the intact pyramidal tracts despite the process of neuronal destruction by Wallerian degeneration. Conventional MRI is not a sensitive test for Wallerian degeneration in the acute or subacute time period as it shows no changes within the first four weeks. Magnetic resonance spectroscopy (MRS) has been used for better quantification of the extent or severity of fibre damage by evaluating metabolite alterations in normal-appearing corticospinal and corticopontal tracts. This study assessed the role of 1H MRS in the detection of changes in cerebral metabolite levels in pyramidal tracts after cortical/ subcortical infarction and to compare metabolite alterations to clinical outcome (assessed by Barthel index, Scandinavian Stroke Scale). The study included 31 patients who had suffered an ischemic cortical/subcortical stroke involving the motor cortex or the descending fibers. Ratios of NAA/Cr, Cho/Cr, lip/Cr and Lac/Cr from internal capsules and cerebral peduncles were measured and compared with clinical status assessed by Barthel index and Scandinavian Stroke Scale (SSS). The ratio of NAA/Cr was significantly decreased (p<0.001) in the normal-appearing ipsilateral internal capsule in comparison with the control group. Cho/Cr and lac/Cr ratios were increased compared to the control group (p=0.019). Decrease of NAA/Cr ratio correlated with clinical status assessed by Barthel index and there was a correlation between clinical improvement (assessed by SSS) and lac/Cr ratio. Tissue metabolite concentrations distant from the infarcted region correlated with the clinical course and had predictive value. Proton MRS is very useful tool for evaluating major changes in metabolite levels in pyramidal tracts after brain stroke.
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PMID:Metabolite Profile in Pyramidal Tracts after Ischemic Brain Stroke Assessed by 1H MRS. A Multicenter Study. 2435 Dec 94

The purpose of this study was to evaluate the roles of different housing environments in neurological function, cerebral metabolism, cerebral infarction and neuron apoptosis after focal cerebral ischemia. Twenty-eight Sprague-Dawley rats were divided into control group (CG) and cerebral ischemia group, and the latter was further divided into subgroups of different housing conditions: standard environment (SE) subgroup, individual living environment (IE) subgroup, and enriched environment (EE) subgroup. Focal cerebral ischemia was induced by the middle cerebral artery occlusion (MCAO). Beam walking test was used to quantify the changes of overall motor function. Cerebral infarction and cerebral metabolism were studied by in vivo magnetic resonance imaging and 1H-magnetic resonance spectra, respectively. Neuron necrosis and apoptosis were detected by hematoxylin-eosin and TUNEL staining methods, respectively. The results showed that performance on the beam-walk test was improved in EE subgroup when compared to SE subgroup and IE subgroup. Cerebral infarct volume in IE subgroup was significantly larger than that in SE subgroup (P<0.05) and EE subgroup (P<0.05) on day 14 after MCAO. NAA/Cr and Cho/Cr ratios were lower in MCAO groups under different housing conditions as compared to those in CG (P<0.05). NAA/Cr ratio was lower in IE subgroup (P<0.05) and higher in EE subgroup (P<0.05) than that in SE subgroup. NAA/ Cr ratio in EE was significantly higher than that in IE subgroup (P<0.05). Cho/Cr ratio was decreased in MCAO groups as compared to that in CG (P<0.05). A significant decrease in normal neurons in cerebral cortex was observed in MCAO groups as compared to CG (P<0.05). The amount of normal neurons was less in IE subgroup (P<0.05), and more in EE subgroup (P<0.05) than that in SE subgroup after MCAO. The amount of normal neurons in EE subgroup was significantly more than that in IE subgroup after MCAO (P<0.05). The ratio of TUNEL-positive neurons in EE was significantly lower than that in SE subgroup (P<0.05) and IE subgroup (P<0.05). Correlation analysis showed that the beam walking test was negatively correlated with NAA/Cr ratio (P<0.05). Cerebral infarct volume was negatively correlated with both NAA/Cr ratio (P<0.01) and Cho/Cr ratio (P<0.01). The amount of normal cortical neurons was positively correlated with both NAA/Cr ratio (P<0.01) and Cho/Cr ratio (P<0.05). The TUNEL-positive neurons showed a negative correlation with both NAA/Cr ratio (P<0.01) and Cho/Cr ratio (P<0.01). This study goes further to show that EE may improve neurological functional deficit and cerebral metabolism, decrease cerebral infarct volume, neuron necrosis and apoptosis, while IE may aggravate brain damage after MCAO.
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PMID:Postischemic Housing Environment on Cerebral Metabolism and Neuron Apoptosis after Focal Cerebral Ischemia in Rats. 3012 75