Stroke; a journal of cerebral circulation
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Transcranial Doppler ultrasonography (TCD) provides useful information on cerebral circulation even under raised intracranial pressure. This study was designed to evaluate the correlation between cerebral blood flow (CBF) and TCD parameters under conditions of boundary intracranial hypertension that can cause brain death. ⋯ The critical level of brain circulation can be detected by Doppler sonography, indicating that TCD is available as a tool for the assessment of cerebral circulatory arrest in brain death.
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Near-infrared spectroscopy (NIRS) derives information about the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) from measurements of light attenuation caused by these chromosphores. The aim of this study was to assess NIRS as a tool for testing CO2 reactivity in patients with carotid artery disease. ⋯ NIRS shows potential as an alternative technique for testing CO2 reactivity in patients with carotid disease provided that conditions are carefully controlled. Marked changes in arterial blood pressure may render the NIRS reactivity indices unreliable, and the contribution from extracranial tissue must be taken into account when significant.
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Hemorrhagic ventricular dilatation (HVD) is a prominent feature of human intraventricular hemorrhage (IVH) and a strong indicator for poor outcome. We developed an IVH model to define the mechanisms responsible for HVD and to test the efficacy of intraventricular administration of tissue plasminogen activator (TPA) in the treatment of HVD. ⋯ These results suggest that intraventricular bleeding may cause impairment of cerebrospinal fluid circulation but that the mass effect of clots distending the ventricle walls is the most important mechanism responsible for HVD. This model closely imitates several prominent features of human IVH and may therefore be a useful tool for preclinical assessment of the efficacy and safety of treatment with TPA.
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Multicenter Study Comparative Study
Ambulatory blood pressure monitoring in acute stroke. The West Birmingham Stroke Project.
Ambulatory blood pressure monitoring (ABPM) devices are increasingly used in the assessment of hypertension, but their value in patients after a stroke is unknown, despite the fact that hypertension is an important cause of stroke and many patients have relatively high blood pressure (BP) levels at presentation. We therefore investigated the clinical use of a 24-hour oscillometric ABPM device in patients after acute stroke. We also investigated ABPM in different types of stroke (thrombosis, hemorrhage, and transient ischemic attack) and ethnic and sex differences. ⋯ This study demonstrates higher systolic BPs as recorded by ABPM (but not manually) in patients with intracerebral hemorrhage than in those with cerebral infarcts; higher levels were also found in blacks. ABPM recordings are useful in the assessment of BP in patients with stroke, who may be considered nondippers.
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Tetrahydrobiopterin (THBP) is an essential cofactor for nitric oxide synthase (NOS), which is responsible for the synthesis of the endothelium-derived relaxing factor (EDRF) responsible for mediating the vasorelaxation produced by acetylcholine (ACh). Previous publications suggest that EDRFACh is continuously synthesized and released from the endothelium of mouse pial arterioles. If so, then one may predict that addition of THBP will increase the local production of EDRFACh and produce an endothelium-dependent relaxation that can be blocked by application of a known inhibitor of NOS. This study tests the prediction. ⋯ The data are consistent with all reports that THBP is a cofactor for constitutive endothelial NOS. The data are consonant with previous results suggesting that EDRFACh is continually synthesized and released. It appears that THBP increases this synthesis and consequently the local level of released EDRFACh. The continuous spontaneous synthesis/release of EDRFACh modulates basal tone and, according to other studies, helps maintain a platelet-free endothelial surface.