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Age-related cerebral blood flow decreases are thought to deteriorate cognition and cause senescence, although the related mechanism is unclear. To investigate the relationships between aging and changes in cerebral blood flow and ...
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Age-related cerebral blood flow decreases are thought to deteriorate cognition and cause senescence, although the related mechanism is unclear. To investigate the relationships between aging and changes in cerebral blood flow and vasculature, we obtained fluorescence images of young (2-month-old) and old (12-month-old) mice using indocyanine green (ICG). First, we found that the blood flow in old mice's brains is lower than that in young mice and that old mice had more curved pial arteries and fewer pial artery junctions than young mice. Second, using Western blotting, we determined that the ratio of collagen to elastin (related to cerebral vascular wall distensibility) increased with age. Finally, we found that the peak ICG intensity and blood flow index decreased, whereas the mean transit time increased, with age in the middle cerebral artery and superior sagittal sinus. Age-related changes in pial arterial structure and composition, concurrent with the observed changes in the blood flow parameters, suggest that age-related changes in the cerebral vasculature structure and distensibility may induce altered brain blood flow. (C) 2016 Elsevier Inc. All rights reserved.
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Objective: Preterm infants frequently receive blood transfusion (BT) and the aim of this study was to measure the effect of BT on cerebral blood flow and oxygenation in preterm infants in relation to chronological age.
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Background. Phenylephrine and ephedrine affect frontal lobe oxygenation (ScO2) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-c...
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Background. Phenylephrine and ephedrine affect frontal lobe oxygenation (ScO2) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-cerebral blood flow and on ScO 2. Methods. In 10 healthy males (age 20-54 yr), phenylephrine or ephedrine was infused for an ~20 mm Hg increase in mean arterial pressure. Cerebral oxygenation (SavO2) was calculated from the arterial and jugular bulb oxygen saturations. Blood flow in the internal carotid artery (ICAf) and blood flow in the external carotid artery (ECAf) were assessed by duplex ultrasonography. Invos-5100c (SinvosO2) and Foresight (SforeO2) determined ScO 2 while forehead skin oxygenation (SskinO2) was assessed. Results. Phenylephrine reduced SforeO2 by 6.9% (95% confidence interval: 4.8-9.0%; P<0.0001), SinvosO2 by 10.5 (8.2-12.9%; P<0.0001), and ECAf (6-28%; P=0.0001), but increased ICAf (5-21%; P=0.003) albeit with no consequence for SskinO 2 or SavO2. In contrast, SforeO 2 was maintained with administration of ephedrine while S invosO2 and SavO2 decreased [by 3.1 (0.7-4.5%; P=0.017) and 2.1 (0.5-3.3%; P=0.012)] as arterial carbon dioxide pressure decreased (P=0.003). ICAf was stable and ECAf increased by 11 (4-18%; P=0.005) with administration of ephedrine while SskinO2 did not change. Conclusions. The effect of phenylephrine on ScO 2 is governed bya decrease in external carotid blood flow since it increases cerebral blood flow as determined by flow in the internal carotid artery. In contrast, ScO2 is largely maintained with administration of ephedrine because blood flow to extracerebral tissue increases.
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Purpose: The aim of this study was to establish the novel automatic method to quantify blood flow volumes of the major intracranial arteries by using SPECT. Methods: We created the vascular templates to cover the territory supplie...
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Purpose: The aim of this study was to establish the novel automatic method to quantify blood flow volumes of the major intracranial arteries by using SPECT. Methods: We created the vascular templates to cover the territory supplied by the major intracranial arteries. Each blood flow volume was calculated as the regional cerebral blood flow on SPECT using this template x volume size of the template. In this study, we evaluated the volume flows in 22 cerebral hemispheres with normal perfusion and 28 hemispheres with severe stenosis in the internal cerebral artery (ICA) or middle cerebral artery (MCA) and that at acet-azolamide test in 16 normal hemispheres and 20 hemispheres with stenosis. Results: The mean blood flow volumes of the ICA and MCA in the normal hemispheres increased to more than 40% after acetazolamide test (161-228 mL/min for ICA and 111-157 mL/min for MCA), although those in the hemispheres with stenosis increased to less than 35% (158-192 mL/min for ICA and 107-127 mL/min for MCA). The receiver operating characteristic analyses revealed that the simple difference between the blood flow volume at acetazolamide test and that at rest using the new MCA template was superior to detecting reduction of cerebrovascular reactivity (CVR), compared with the conventional percent CVR using the original template. Conclusions: Blood flow volumes of the intracranial arteries had been able to be quantified automatically on SPECT, and difference of CVR was available for predicting the blood demand-supply balance.
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Subarachnoid hemorrhage (SAH) is a devastating disease with approximately 30% early case fatality. Of the 70% who survive the ictus, despite early resuscitation.
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ObjectiveThe purpose of this study was to evaluate the changes in Doppler blood flow velocity (BFV) in cerebral and visceral arteries during infancy.
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The cerebral microvasculature plays a key role in the transport of blood and the delivery of nutrients to the cells that perform brain function. Although recent advances in experimental imaging techniques mean that its structure a...
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The cerebral microvasculature plays a key role in the transport of blood and the delivery of nutrients to the cells that perform brain function. Although recent advances in experimental imaging techniques mean that its structure and function can be interrogated to very small length scales, allowing individual vessels to be mapped to a fraction of 1 mu m, these techniques currently remain confined to animal models. In-vivo human data can only be obtained at a much coarser length scale, of order 1 mm, meaning that mathematical models of the microvasculature play a key role in interpreting flow and metabolism data. However, there are close to 10,000 vessels even within a single voxel of size 1 mm(3). Given the number of vessels present within a typical voxel and the complexity of the governing equations for flow and volume changes, it is computationally challenging to solve these in full, particularly when considering dynamic changes, such as those found in response to neural activation.
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