Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
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J. Cereb. Blood Flow Metab. · Feb 2000
Comparative Study Clinical TrialAssessment of hemispheric language lateralization: a comparison between fMRI and fTCD.
The cerebral blood flow velocity (CBFV) in the basal arteries during a word-generation task was assessed by functional transcranial Doppler ultrasonography (fTCD) and by functional magnetic resonance imaging (fMRI). The study investigates how event-related CBFV modulations in the middle cerebral artery (MCA) relate to regional cerebral blood flow (rCBF) changes. Both fMRI and fTCD were used in 13 subjects (7 men, 6 women, aged 21 to 44 years). ⋯ The evoked CBFV changes expressed by LIfTCD and the corresponding laterality index, LIfMRI, estimated by fMRI showed a close linear relation (regression analysis: r = 0.95, p < 0.0001). The results of this study demonstrate that language-related velocity changes in the MCAs relate to rCBF increases in a linear fashion. Since the laterality indices assessed by fMRI and fTCD are in such close agreement both techniques can therefore be used in a complementary way.
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J. Cereb. Blood Flow Metab. · Feb 2000
Induction of angiopoietin and Tie receptor mRNA expression after cerebral ischemia-reperfusion.
The angiopoietin/Tie receptor system may contribute to angiogenesis and vascular remodeling by mediating interactions of endothelial cells with smooth muscle cells and pericytes. The temporal expression of angiopoietin-1 (Angpo-1), angiopoietin-2 (Angpo-2), Tie-1, and Tie-2 mRNA was studied in a focal cerebral ischemia model in rats. The cDNA fragments obtained from reverse transcription polymerase chain reaction amplification were cloned and used as a probe to detect individual genes. ⋯ The temporal profiles of the expression of these genes were different from those of other angiogenic genes such as basic fibrobast growth factor/fibroblast growth factor receptor and vascular endothelial growth factor/vascular endothelial growth factor receptor and proteolytic enzymes (tissue-type plasminogen activator and urokinase plasminogen activator) and their inhibitors (plasminogen activator inhibitor-1). The expression patterns of these genes could be related to progressive tissue liquefaction and neovascularization after ischemia in this stroke model. Differential expression of these angiogenesis genes suggests the involvement of complex regulatory mechanisms that remain to be characterized.
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J. Cereb. Blood Flow Metab. · Jan 2000
Effect of JTP-2942, a novel thyrotropin-releasing hormone analog, on motor deficits after chronic focal cerebral ischemia in rats.
To investigate the chronic effects of a novel thyrotropin-releasing hormone analog, JTP-2942 (N(alpha)-[(1S, 2R)-2-methyl-4-oxocyclopentylcarbonyl]-L-histidyl-L-prolinamide monohydrate), on behavioral changes after stroke, the authors examined its effects on motor and neurologic deficits using a middle cerebral artery (MCA) occlusion model in rats. A left MCA was permanently occluded at a proximal site. From 1 week after occlusion, JTP-2942 was intravenously administered once a day for 4 weeks. ⋯ In the present study, long-lasting improving effects of JTP-2942 on the impairment of motor and neurologic functions were observed in rats with MCA occlusion, which continued after cessation of drug administration and which were not attributable to a reduction in ipsilateral cerebral shrinkage. It is considered that the effect of JTP-2942 on functional recovery is attributable to the activation of substitutive functions such as neuronal reconstruction. These pharmacologic properties of JTP-2942 may be of interest for the treatment of patients with motor and neurologic deficits during the chronic or subacute phase of stroke.
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J. Cereb. Blood Flow Metab. · Oct 1999
Spectral analysis of arterial blood pressure and cerebral blood flow velocity during supine rest and orthostasis.
This study evaluates the effect of orthostasis on the low frequency (LF, 0.04 to 0.15 Hz) fluctuations in the blood flow velocity of the middle cerebral artery (MCAFV) in relation to its arterial blood pressure (ABP) equivalent to further define and quantify this relationship in cerebrovascular regulation. Spectral analysis was performed on 22 healthy subjects during supine rest and head-up tilt. The power in the LF range can be used to quantify the LF fluctuations, and four types of LF power data could be obtained for each individual: LF power of supine MCAFV, LF power of supine ABP, LF power of tilt MCAFV, and LF power of tilt ABP. ⋯ The authors found that this index was dependent on the extent of orthostatic MCAFV changes, and the dependency could be mathematically expressed (r = 0.61, P = .0001), suggesting its involvement in cerebrovascular regulation. Moreover, these data further support the previous observation that the LF fluctuations of MCAFV might result from modulation of its ABP equivalent, and the modulation effect could be quantified as the power ratio (LF power of MCAFV/ LF power of ABP). These observations could be an important step toward further insight into cerebrovascular regulation, which warrants more research in the future.
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J. Cereb. Blood Flow Metab. · Sep 1999
Cerebral vasodilatation causing acute intracranial hypertension: a method for noninvasive assessment.
Deep spontaneous vasodilatatory events are frequently recorded in various cerebral diseases, causing dramatic increases (A-waves) in intracranial pressure (ICP) and subsequently provoking ischemic brain insults. The relationship between fluctuations in CBF, ICP, and arterial blood pressure (ABP) is influenced by properties of cerebrovascular control mechanisms and the cerebrospinal pressure-volume compensation. The goal of this study was to construct a mathematical model of this relationship and to assess its ability to predict the occurrence and time course of A-waves. ⋯ The correlation coefficient between real and simulated increase in ICP was R = 0.98; P < .001. Similarly, correlation between real and simulated increase in pulse amplitude of ICP was highly significant (R = 0.94; P < .001). The mathematical model of the relationship between ABP, flow velocity, and ICP is of potential clinical use for the noninvasive detection of A-waves in patients in whom invasive ICP assessment is not conducted.