bluuebunny/crossref_metadata_2025_split huggingface dataset:
The onset of postischemic hypoperfusion in rats is precipitous and may be controlled by local neurons.
Authors: Frerichs K U , Sirén A L , Feuerstein G Z , Hallenbeck J M 
Published: June 2011

Reperfusion following transient global cerebral ischemia is characterized by an initial hyperemic phase, which precedes hypoperfusion. The pathogenesis of these flow derangements remains obscure. Our study investigates the dynamics of postischemic cerebral blood flow changes, with particular attention to the role of local neurons.
We assessed local cortical blood flow continuously by laser Doppler flowmetry to permit observation of any rapid flow changes after forebrain ischemia induced by four-vessel occlusion for 20 minutes in rats. To investigate the role of local cortical neurons in the regulation of any blood flow fluctuations, five rats received intracortical microinjections of a neurotoxin (10 micrograms ibotenic acid in 1 microliter; 1.5-mm-depth parietal cortex) 24 hours before ischemia to induce selective and localized neuronal depletion in an area corresponding to the sample volume of the laser Doppler probe (1 mm3). Local cerebral blood flow was measured within the injection site and at an adjacent control site.
Ischemia was followed by marked hyperemia (235 +/- 23% of control, n = 7), followed by secondary hypoperfusion (45 +/- 3% of control, n = 7). The transition from hyperemia to hypoperfusion occurred not gradually but precipitously (maximal slope of flow decay: 66 +/- 6%/min; n = 7). In ibotenic acid-injected rats, hyperemia was preserved at the injection site, but the sudden decline of blood flow was abolished (maximal slope of flow decay: 5 +/- 3%/min compared with 53 +/- 8%/min at the control site; n = 5, p less than 0.001) and no significant hypoperfusion developed (103 +/- 20% of control at 60 minutes).
These data suggest that the rapid transition to cortical hypoperfusion after forebrain ischemia may be triggered locally by a neuronal mechanism but that this mechanism does not underlie the initial hyperemia.
Concurrent myocardial and cerebral infarctions after intranasal cocaine use.
Authors: Sloan M A , Mattioni T A 
Published: June 2011

Cardiac and cerebrovascular complications associated with cocaine abuse have increasingly been reported, but concurrent development of cocaine-induced cardiac disease and stroke has rarely been reported.
A 37-year-old man with a remote history of intravenous heroin and amphetamine use, cardiomyopathy, and recent cocaine use developed chest pain and ventricular tachycardia 30 minutes after intranasal cocaine hydrochloride use and jogging on a cold winter morning. Ventricular tachycardia was converted to atrial fibrillation. He was proven to have a small myocardial infarction. Within 6 hours of cocaine use he suffered a left hemisphere stroke. Cardiac electrophysiologic evaluation revealed inducible ventricular tachycardia.
To our knowledge, this is the first report of concurrent myocardial infarction, life-threatening ventricular arrhythmias, and cerebral infarction temporally related to cocaine use. It is probable that one mechanism by which cocaine use causes stroke is to trigger expression of a known cardiac source of embolism.
Improved prognosis for asymptomatic carotid stenosis with prophylactic carotid endarterectomy.
Authors: Freischlag J A , Hanna D , Moore W S 
Published: June 2011

The value of carotid endarterectomy in asymptomatic patients with high-grade stenosis is controversial. The objective of this study is to compare the immediate and long-term outcome of patients after carotid endarterectomy for asymptomatic carotid stenosis (greater than 75%) with the reported natural history of patients followed nonoperatively to determine whether carotid endarterectomy reduces the subsequent neurological event rate.
The data from 141 carotid endarterectomies performed in 123 patients between January 1980 and December 1986 were reviewed from the perspective of perioperative results and long-term follow-up to January 1990, providing a follow-up ranging from 3 to 10 years. The mean follow-up was 56.6 months (range 27-117 months).
There were no perioperative deaths. There were two postoperative stokes: one in the cerebellar distribution and one in the middle cerebral distribution. During the course of follow-up, no patient suffered a stroke in the hemisphere ipsilateral to carotid endarterectomy. One patient developed ipsilateral transient ischemic attacks 24 months after surgery associated with carotid restenosis. A total of three patients developed four recurrent carotid stenoses, for an incidence of 2.8%. All four recurrences were corrected surgically.
These findings are in marked contrast to the reported natural history of patients with greater than 75% stenosis in which the 1-year neurological event rate is 18% and the 1-year stroke rate is 5%. Although final proof of efficacy for prophylactic carotid endarterectomy in asymptomatic patients will await the outcome of randomized trials, until these data are available, prophylactic carotid endarterectomy is justified in centers of excellence that can perform the surgery with low perioperative risk.
T2- and diffusion-weighted magnetic resonance imaging of a focal ischemic lesion in rat brain.
Authors: van Bruggen N , Cullen B M , King M D , Doran M , Williams S R , Gadian D G , Cremer J E 
Published: June 2011

We sought to evaluate the application of T2-weighted and diffusion-weighted magnetic resonance imaging techniques in the study of a focal ischemic lesion in the rat brain.
Unilateral cortical infarcts were induced using the photosensitive dye rose bengal and 560 nm light irradiation. Magnetic resonance images were recorded from a total of 11 rats at selected intervals from 1.5 hours to several days after induction of the lesion. Parallel experiments were performed in which Evans blue dye was injected into the lesioned animals either immediately after lesion induction (n = 11) or 1 hour before the animals were killed (n = 11). The second procedure was designed to show regions of blood-brain barrier permeability to plasma proteins at the time of sacrifice, whereas the first procedure showed the accumulation and subsequent dispersion of plasma protein following disruption of the blood-brain barrier.
Regions of the cortex highlighted by the T2-weighted images corresponded well to the pattern of dye staining seen from the first procedure while the diffusion-weighted images showed visual correspondence with the staining pattern obtained using the second procedure.
These results illustrate the complementary use of T2-weighted and diffusion-weighted magnetic resonance imaging in discerning the pathophysiology of developing lesions.
Mild hypothermia reduces infarct size resulting from temporary but not permanent focal ischemia in rats.
Authors: Ridenour T R , Warner D S , Todd M M , McAllister A C 
Published: June 2011

Mild hypothermia (32-35 degrees C) has been repeatedly shown in laboratory models to reduce damage resulting from global cerebral ischemic insults. Little information is available, however, regarding the protective potential of mild hypothermia against focal ischemia. We designed the present study to determine whether mild hypothermia influences outcome from either temporary or permanent middle cerebral artery occlusion in the rat.
In experiment 1 (permanent occlusion), mechanically ventilated, halothane-anesthetized spontaneously hypertensive rats underwent permanent ligation of the middle cerebral artery. Pericranial temperature was maintained at either 37 degrees C (n = 11) or 33 degrees C (n = 11) during the first 2 hours of occlusion. In experiment 2 (temporary occlusion), the vessel was occluded for 1 hour only. Pericranial temperature was controlled at either 37 degrees C (n = 12) or 33 degrees C (n = 14) during ischemia and for 1 hour after reperfusion. In both experiments, the rats were allowed to recover, with neurological function scored at 24 and 96 hours after onset of ischemia. Cerebral infarct volume (as determined by nitro blue tetrazolium staining) was planimetrically evaluated 96 hours after onset of ischemia.
No difference in infarct volume was observed between groups undergoing permanent occlusion (177 +/- 53 mm3 for 37 degrees C rats, 167 +/- 71 mm3 for 33 degrees C rats [mean +/- SD]). Although neurologic function correlated with infarct volume at 96 hours (all animals in experiment 1 combined; p less than 0.01), we were unable to demonstrate an intergroup difference in function. In animals undergoing temporary occlusion, mean +/- SD infarct volume was 48% less in the hypothermic group (89 +/- 54 mm3 for 37 degrees C, 46 +/- 31 mm3 for 33 degrees C; p less than 0.03). Neurological function again correlated with infarct size (p less than 0.02), but improvement in function approached significance for the hypothermic group (p less than 0.06) at 24 hours after reperfusion only.
Benefits from mild hypothermia may be obtained under conditions of temporary but not permanent middle cerebral artery occlusion in the rat.
Mechanism of detection of acute cerebral ischemia in rats by diffusion-weighted magnetic resonance microscopy.
Authors: Benveniste H , Hedlund L W , Johnson G A 
Published: June 2011

The aim of this study was to measure apparent diffusion coefficients in rat brain tissue exposed to ouabain, glutamate, and N-methyl-D-aspartate and to compare them with apparent diffusion coefficients found in acute cerebral ischemia.
The apparent diffusion coefficient was measured using magnetic resonance microscopy in four groups of Sprague-Dawley rats after occlusion of the right middle cerebral artery and ipsilateral common carotid artery (n = 7), after ouabain exposure (n = 6), during glutamate exposure (n = 7), or during N-methyl-D-aspartate exposure (n = 3). Ouabain, glutamate, and N-methyl-D-aspartate were applied via an intracerebrally implanted microdialysis membrane.
Three hours after the induction of focal cerebral ischemia, a 33% reduction in the apparent diffusion coefficient was observed in the right dorsolateral corpus striatum and olfactory cortex. After ouabain exposure, reductions in the apparent diffusion coefficient were observed within a 1,500-microns radius of the microdialysis membrane. Quantitative analysis revealed that apparent diffusion coefficient values in ischemic and ouabain-exposed tissue fell within the same range. Glutamate and N-methyl-D-aspartate reduced the brain tissue apparent diffusion coefficient by 35% and 40%, respectively.
On the basis of these findings, we conclude that ischemia-induced apparent diffusion coefficient reductions are likely caused by a shift of extracellular to intracellular water.
Prevalence and etiology of dementia in a Japanese community.
Authors: Ueda K , Kawano H , Hasuo Y , Fujishima M 
Published: June 2011

We sought to determine the type-specific prevalence of dementia and its risk factors in elderly persons from the Japanese community of Hisayama.
We studied the prevalence of dementia in 887 Hisayama residents (353 men and 534 women) aged 65 years or older (screening rate, 94.6%) using various items of clinical information, neurological examination, and dementia scales. We also studied brain morphology in 50 of 59 determined to have dementia by computed tomography or autopsy during the subsequent 54-month period. Factors relevant to dementia were compared between 27 patients with vascular dementia and 789 control subjects without dementia in a retrospective fashion.
The prevalence rate of dementia among Hisayama residents aged 65 or older was estimated at 6.7%, with a females to males ratio of 1:2. Among 50 cases of dementia in which brain morphology was examined, the frequency of vascular dementia was 56%; this rate was 2.2 times higher than that for senile dementia of the Alzheimer type. Aging, hypertension, electrocardiographic abnormalities, and high hematocrit were significantly (p less than 0.05) and independently associated with the occurrence of vascular dementia.
Prevalence of dementia among the Hisayama residents was relatively identical to that previously reported, but vascular dementia was more predominant. Risk factors for vascular dementia were similar to those for lacunar infarcts. Control of hypertension may be a key to reducing dementia among the Japanese population.
Cranial computed tomographic observations in multi-infarct dementia. A controlled study.
Authors: Gorelick P B , Chatterjee A , Patel D , Flowerdew G , Dollear W , Taber J , Harris Y 
Published: June 2011

We compared cranial computed tomography findings among 58 multi-infarct dementia index cases and 74 multi-infarct control subjects without cognitive impairment to identify potential determinants of multi-infarct dementia.
The cranial computed tomography records of acute ischemic stroke patients with a history of multiple cerebral infarcts were compared to determine the number, location, and size of cerebral infarcts; the pattern of infarction; brain volume loss; and the degree of white matter lucency, sulcal enlargement, and ventricular enlargement. Multi-infarct patients were divided into two groups: 1) index cases were defined as those with multi-infarct dementia as defined by the Diagnostic and Statistical Manual of Mental Disorders, edition 3 (DSM-III) criteria; and 2) control subjects were defined as those multi-infarct patients without dementia or multi-infarct dementia according to DSM-III criteria.
Overall, multi-infarct index cases had more cerebral infarcts, more cortical and subcortical left hemisphere infarcts, higher mean ventricular volume to brain volume ratio, more extensive enlargement of the body of the lateral ventricles and cortical sulci, and a higher prevalence of white matter lucencies. Among multi-infarct cases and control subjects the most frequent site of infarction was the subcortical region, and the most frequent pattern of infarction was lacunar. Stepwise logistic regression analysis examined cranial computed tomography as well as other factors and showed that level of education, stroke severity, left cortical infarction, and diffuse enlargement of the left lateral ventricle were the best overall predictors of multi-infarct dementia.
Level of education, stroke severity, and left hemisphere infarction may be predictors of multi-infarct dementia.
Prevalence of extracranial carotid artery disease detectable by echo-Doppler in an elderly population.
Authors: Pujia A , Rubba P , Spencer M P 
Published: June 2011

Little information is available on extracranial carotid artery disease in free-living elderly individuals. We sought to evaluate the prevalence of carotid lesions in the elderly.
Using echo-Doppler, we assessed the prevalence of possible atherosclerotic lesions in the internal carotid arteries (n = 478) and the external and common carotid arteries (n = 956) of 239 subjects 65-94 years of age living in retirement homes in Seattle, Wash.
We found that 152 (31.8%) internal carotid arteries were affected by nonstenosing plaque and 37 arteries (7.7%) had stenosis or occlusion. In addition, 193 (20.2%) external or common carotid arteries showed nonstenosing plaques. There were 128 subjects (53.6%) with internal carotid disease, 106 (44.3%) with evidence of external or common carotid disease, and 75 (31.4%) affected by disease in all three sites. There were 80 subjects (33.5%) with no ultrasound evidence of carotid disease. We found that the presence and severity of carotid disease increased between the decades 65-74 and 75-84. We also demonstrated a positive association between systolic blood pressure and ultrasound evidence of carotid disease that was independent of age.
The prevalence of extracranial artery disease in an apparently healthy population was high, although stenoses in most instances were not severe. We conclude that noninvasive ultrasound methods identify a relatively small fraction of individuals (5% of the total) at high risk for stroke or transient ischemic attack. Echo-Doppler might be used to monitor further disease progression and to evaluate the efficacy of different therapeutic or preventive interventions.
European stroke prevention study: effectiveness of antiplatelet therapy in diabetic patients in secondary prevention of stroke.
Authors: Sivenius J , Laakso M , Riekkinen P , Smets P , Lowenthal A 
Published: June 2011

The European Stroke Prevention Study was a multicenter trial comparing the effect of a combination of 75 mg dipyridamole and 330 mg acetylsalicylic acid three times a day with the effect of a placebo in the prevention of stroke or death in 1,861 patients after one or more episodes of recent transient ischemic attack or cerebral infarction.
The present study represents a secondary analysis of the efficacy of study medication in diabetic (n = 216) and nondiabetic (n = 1,645) patients.
The risk of end point events was greater in diabetic than in nondiabetic subjects. Total end point reduction in individuals receiving the combination of dipyridamole and acetylsalicylic acid was 39% in nondiabetic subjects and 23% in diabetic subjects in the explanatory analysis, and the reduction in the risk of stroke was 48% and 32%, respectively. However, a statistically significant reduction of risk was obtained only in nondiabetic subjects.
The combination of dipyridamole and acetylsalicylic acid appeared to be more effective in nondiabetic subjects than in diabetic subjects in the prevention of death and stroke although the low number of diabetic patients may at least in part explain this result.
Hemodynamic and metabolic changes in crossed cerebellar hypoperfusion.
Authors: Yamauchi H , Fukuyama H , Kimura J 
Published: June 2011

The pathophysiology of crossed cerebellar diaschisis remains to be elucidated. The mechanism responsible appears to be deafferentation through the corticopontocerebellar tract, which terminates in the cerebellar gray matter. However, few studies have demonstrated the hemodynamic and metabolic changes in the cerebellar gray matter and pons in crossed cerebellar diaschisis.
Using positron emission tomography in 24 patients with unilateral supratentorial stroke, we evaluated regional blood flow, metabolic rate of oxygen, oxygen extraction fraction, and blood volume in the cerebellar cortex and pons. Sixteen patients with significant cerebellar blood flow asymmetry, defined as a percentage difference in blood flow beyond the upper 95% confidence limit defined in eight normal subjects, were selected as the group with crossed cerebellar hypoperfusion.
In patients with crossed cerebellar hypoperfusion, the metabolic rate of oxygen was significantly decreased in the cerebellar cortex contralateral to the supratentorial stroke, compared with that in the ipsilateral cerebellar cortex; this decrease was less than the decrease in cerebellar blood flow. The degrees of cerebellar asymmetry in these two parameters were negatively correlated with the metabolic rate of oxygen in the pons. The oxygen extraction fraction was slightly, but significantly, increased. In contrast to the ischemic state, however, the cerebellar blood volume was decreased, with no difference in the ratio of cerebellar blood flow to blood volume.
These findings support interruption of the corticopontocerebellar tract as the mechanism of crossed cerebellar hypoperfusion. Our results also suggest a mild elevation in the oxygen extraction fraction in this state, with a mechanism distinct from ischemia.
Stroke after pituitary irradiation.
Authors: Bowen J , Paulsen C A 
Published: June 2011

Cranial irradiation may lead to accelerated atherosclerosis over several years. Stroke has been described after cranial irradiation administered for a number of conditions. However, pituitary irradiation has only rarely been associated with stroke.
Two patients, 39 and 46 years of age, suffered strokes 13 and 20 years, respectively, after irradiation for pituitary tumors. Strokes were in the territories of small perforating arteries, but large vessels such as the carotid siphon and anterior cerebral arteries were also abnormal. Other risk factors for stroke were absent.
It is suggested that pituitary irradiation increases the risk of subsequent stroke due to the known effects of ionizing radiation on vascular walls.
Role of ticlopidine for prevention of stroke.
Authors: Albers G W 
Published: June 2011

Ticlopidine, an antiplatelet agent with a unique mechanism of action, is now available for clinical use in the United States and Canada.
Recently two large randomized trials demonstrated that ticlopidine can reduce the risk of subsequent stroke in patients presenting with a transient ischemic attack or stroke. One study found that ticlopidine was more effective than aspirin for stroke prevention; however, it was less well tolerated than aspirin and was associated with severe but reversible neutropenia in almost 1% of patients.
Ticlopidine is effective for both primary and secondary stroke prevention. It has a favorable risk/benefit ratio and is a particularly attractive option for patients who are unable to take aspirin.
Ultrasonic measurement of the elastic modulus of the common carotid artery. The Atherosclerosis Risk in Communities (ARIC) Study.
Authors: Riley W A , Barnes R W , Evans G W , Burke G L 
Published: June 2011

The Atherosclerosis Risk in Communities Study is a prospective investigation of the etiology and natural history of atherosclerosis and the etiology of clinical disease in four US communities.
Noninvasive ultrasonic methods were used to determine mean wall thickness (WT), radius (R), and circumferential arterial strain (CAS) in the left common carotid artery of 3,321 white male and female study participants between the ages of 45 and 64 years. The mean and standard deviation of Young's elastic modulus (Y) in 5-year age groups were determined for each sex by combining the ultrasonic data with concurrent noninvasive measurements of pulse pressure (PP) in the right brachial artery using the equation Y = (R/WT) x (PP/CAS).
Significant (p = 0.0001) age group differences in Y were observed in both sexes, with the mean value increasing from 701 kPa in women and 771 kPa in men in the 45-49-year-old age group to 965 and 983 kPa, respectively, in the 60-64-year-old age group. Significant (p = 0.0001) age group differences were also observed for WT, the WT/R ratio, PP, CAS, and the PP/CAS ratio in both sexes. A sex difference in Y was detected (male greater than female, p = 0.0006) only in the 45-49-year-old age group. Significant (p less than 0.0001) sex differences were found, with men having a greater lumen diameter calculated as 2 x (R - WT), a greater WT, and a greater 2R in all age groups. The WT/R ratio did not differ in both sexes in all age groups.
Knowledge of the arterial wall elastic modulus and the parameters required for its determination can provide important insight into structural changes occurring within the arterial wall with age and sex, and possibly with the onset of very early arterial disease.