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A theoretical model of blood-brain exchange is developed and a procedure is derived that can be used for graphing multiple-time tissue uptake data and determining whether a unidirectional transfer process was dominant during part or all of the experimental period. If the graph indicates unidirectionality of uptake, then an influx constant (Ki) can be(More)
BACKGROUND AND PURPOSE The early ischemic lesions demonstrated by diffusion-weighted imaging (DWI) are potentially reversible. The purposes of this study were to determine whether resolution of initial DWI lesions is transient or permanent after different brief periods of focal brain ischemia and to evaluate histological outcomes. METHODS Sixteen rats(More)
This study was designed to characterize the initial and secondary changes of the apparent diffusion coefficient (ADC) of water with high temporal resolution measurements of ADC values and to correlate ADC changes with functional outcomes. Fourteen rats underwent 30 minutes of temporary middle cerebral artery occlusion (MCAO). Diffusion-, perfusion-, and(More)
Spontaneously hypertensive rats (SHR) are hypertensive, hyperactive, and hydrocephalic; furthermore SHR have smaller brain volume and weight than age-matched, normotensive Wistar-Kyoto rats (WKY). At 6-7 months of age, local cerebral glucose is sizably lower in SHR than WKY. The hypothesis that these several abnormalities of SHR lead to variations in(More)
Utilizing a ventricular perfusion technique, the rate of CSF formation was determined in a 2-year-old child before and after removal of a 74 g choroid plexus papilloma from the left lateral ventricle. Preoperatively, the CSF formation rate was 1.05 +/- SD 0.01 ml/min (1,656 ml/day). Postoperatively, the CSF formation rate was reduced fivefold to 0.20 +/- SD(More)
The single-capillary model was applied to the exchange microvessels for water in the cerebral parenchyma and used to calculate blood-to-brain flux of water; the theory of the steady-state arterial spin-tagging (AST) technique for estimating cerebral blood flow (CBF) was revised to incorporate the presence of both extravascular (tissue) and capillary signal.(More)
Blood volume, blood flow, and blood-to-tissue transfer of an amino acid in circumventricular organs, such as the median eminence and subfornical organ, and the pituitary gland of conscious rats were measured by using quantitative autoradiographic techniques and computer-assisted processing of the tissue images. Retained erythrocyte and plasma volumes(More)
Physiological and morphometric studies were conducted on the microvascular endothelium of four individual cerebral structures having different neural activities--the inferior colliculus, sensorimotor cortex (both gray matter regions), genu of the corpus callosum (white matter), and the subfornical organ (a circumventricular organ) of rats. The physiological(More)
In Alzheimer's disease, the neuritic or senile amyloid plaques in hippocampus and association cortex, the diffuse plaques in brain areas such as the cerebellum and sensorimotor cortex, and the amyloid deposits in the walls of pial and parenchymal blood vessels are mainly composed of amyloid beta-peptides. In the present study, either soluble 40-residue(More)
The blood-to-brain transfer rate constant (K(i)) of Gd-DTPA was determined in MRI studies of a rat model of transient cerebral ischemia. The longitudinal relaxation rate, R(1), was estimated using repeated Look-Locker measurements. A model-independent analysis of deltaR(1), the Patlak plot, produced maps of K(i) for Gd-DTPA and the distribution volume of(More)