bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of bradykinin- and kallikrein-induced cerebral arteriolar dilation by a specific bradykinin antagonist.
Authors: Ellis E F , Heizer M L , Hambrecht G S , Holt S A , Stewart J M , Vavrek R J
Published: June 2011

We have previously shown that topical brain application of kallikrein, an enzyme which converts kininogen to bradykinin, induces rabbit pial arteriole dilation. The purpose of the present investigation was to utilize a newly developed competitive kinin receptor antagonist to test the hypothesis that kallikrein-induced dilation was due to the conversion of brain kininogen to vasoactive kinins. As in our previous study, we measured rabbit pial arteriole diameter with a microscope using the closed cranial window technique. The kinin antagonist (6 microM) reduced the dose-dependent dilation produced by bradykinin and blocked the dilation induced by kallikrein. In addition, the kinin antagonist was specific since it did not alter the cerebral arteriole dilation produced by adenosine, acetylcholine, or vasoactive intestinal polypeptide. These experiments provide further evidence for a possible role of the endogenous brain kallikrein-kinin system in the modulation of the cerebral circulation and provide the necessary pharmacologic foundation for future use of this antagonist in testing the role of kinins in the normal or altered cerebral circulation.
Carotid and lower extremity arterial disease in elderly adults with isolated systolic hypertension.
Authors: Sutton K C , Wolfson S K , Kuller L H
Published: June 2011

The prevalence of carotid and lower extremity arterial disease was assessed in a healthy population of 56 elderly adults with isolated systolic hypertension. Duplex scans were performed to determine the extent of carotid disease, and postexercise ratios of ankle to arm systolic blood pressure were measured to assess lower extremity arterial disease. Internal carotid stenosis was found in 38% (21 of 56) of subjects and lower extremity arterial disease in 42% (23 of 55). The strongest predictor of internal carotid stenosis was lower extremity arterial disease. Independent risk factors for lower extremity arterial disease were smoking, internal carotid stenosis, and age. A measure of extent of carotid plaque was found to correlate with age, carotid stenosis, male sex, history of smoking, and total cholesterol. The high prevalence of peripheral vascular disease in this population may be related to their age and blood pressure. The high correlation between carotid stenosis and lower extremity arterial disease suggests that persons with peripheral vascular disease should be assessed and treated for atherosclerotic disease in general.
Declining morbidity and mortality of carotid endarterectomy. The Wake Forest University Medical Center experience.
Authors: Till J S , Toole J F , Howard V J , Ford C S , Williams D
Published: June 2011

The 30-day mortality as well as morbidity for stroke and myocardial infarction were determined by review of the charts for every carotid endarterectomy (N = 389 operations on 356 patients) performed at Wake Forest University Medical Center from 1979 through 1983 to ascertain whether the 16% morbidity and 6% mortality documented in our previous report of 1978 had changed over time. For endarterectomies performed on asymptomatic patients (n = 155), major morbidity included 2 myocardial infarctions and 1 stroke (1.9%). There were 3 fatalities--2 myocardial infarctions and 1 stroke (1.9%). For the symptomatic group (n = 234), major morbidity was 2.1%, mortality 2.6%. The combined morbidity for asymptomatic and symptomatic carotid stenosis was 2%, mortality 2.3%. Perioperative stroke rate (morbidity plus mortality) was 2.6%, 9 ipsilateral to the carotid endarterectomy, suggesting distal embolism as its probable cause. We contend that quality control measures implemented to correct the unacceptable rates reported in 1978 have contributed to dramatic and sustained reductions in complication rates.
Operative versus nonoperative management of asymptomatic high-grade internal carotid artery stenosis: improved results with endarterectomy.
Authors: Moneta G L , Taylor D C , Nicholls S C , Bergelin R O , Zierler R E , Kazmers A , Clowes A W , Strandness D E
Published: June 2011

In a 4-year period, 129 asymptomatic high-grade (80-99%) internal carotid artery stenoses were identified in 115 patients. Because we previously demonstrated a strong relation between degree of carotid stenosis and subsequent development of ipsilateral related events (stroke, transient ischemic attack, and carotid occlusion), we changed our previous policy and began to offer carotid endarterectomy to good surgical risk patients referred to us with asymptomatic high-grade carotid stenosis. A total of 56 carotid endarterectomies were performed while 73 lesions were followed nonoperatively. Operated and nonoperated groups were similar with regard to age, prevalence of hypertension, cardiac disease, diabetes, and aspirin use. Life table analysis to 24 months revealed a higher rate of stroke (19 vs. 4%, p = 0.08), transient focal neurologic deficits (28 vs. 5%, p = 0.008), and carotid occlusion (29 vs. 0%, p = 0.003) in the nonoperated group. Eight of the 9 strokes in the nonoperated group occurred within 9 months of diagnosis of the high-grade lesion; none were preceded by a transient ischemic attack. There was 1 perioperative stroke (1.8%) but no in-hospital operative deaths and no difference in the late death rates of the two groups. This suggests that the preservation of neurologic status in patients with asymptomatic high-grade internal carotid artery stenosis can be improved by carotid endarterectomy.
Evaluation of cerebrovascular disease by combined extracranial and transcranial Doppler sonography. Experience in 1,039 patients.
Authors: Grolimund P , Seiler R W , Aaslid R , Huber P , Zurbruegg H
Published: June 2011

Results from 1,039 combined cervical and transcranial Doppler examinations are reported. Satisfactory transcranial signals were not found in 2.7% of the cases. Compared with angiography, the accuracy of transcranial criteria in assessing collateral flow over the circle of Willis was 94 and 88% for anterior and posterior circulation, respectively. The method also appeared very promising for detection of lesions of the intracranial arteries although the number of such cases with angiographic verification was limited in the present series. Arterial narrowing due to cerebral vasospasm was diagnosed with a sensitivity of 80%. In patients with ruptured intracranial aneurysms, an incidence of 93% arterial narrowing in basal cerebral arteries was found. Patients with subarachnoid hemorrhage and no aneurysm on angiography also showed arterial narrowing with an incidence of 56%. It was possible to monitor the time course and severity of cerebral vasospasm. Arteriovenous malformations were characterized by Doppler findings of high velocities and low pulsatilities. These lesions were diagnosed with an accuracy of 95%.
Cerebral blood flow asymmetries in headache-free migraineurs.
Authors: Levine S R , Welch K M , Ewing J R , Joseph R , D'Andrea G
Published: June 2011

Regional cerebral blood flow (rCBF) asymmetries were studied in controls and patients with common and classic/complicated migraine using 133Xe inhalation with 8 homologously situated external collimators over each cerebral hemisphere. Migraine patients as a group more frequently had posterior rCBF asymmetries than controls (p less than 0.03). Although there were no differences in the number of anterior rCBF asymmetries, migraine patients had 2 or more asymmetric probe pairs more often than controls (p less than 0.02). The posterior rCBF asymmetries, consistent with the site of activation of many migraine attacks, may be related to more labile control of the cerebral circulation.
Prognosis of high-risk patients with nonoperated symptomatic extracranial carotid tight stenosis.
Authors: Bogousslavsky J , Despland P A , Regli F
Published: June 2011

Forty-five patients with symptomatic (20 with transient ischemic attack, 25 with minor stroke) greater than or equal to 75% stenosis of the cervical internal carotid artery had no endarterectomy and received only medical therapy because the surgical risks (severe cardiac disease, chronic obstructive pulmonary disease, hypertension or diabetes with systemic complications, aortic aneurysm) were believed to be unacceptable. During follow-up (mean 48 months), occlusion of the internal carotid artery developed without symptoms in two patients and with symptoms in three patients. The cumulative stroke and/or death rate was 24% at 2 years and 50% at 6 years. The ipsilateral infarct rate was 10% after the first year, but decreased markedly thereafter (2.4% per year), and one third of these infarcts were probably lacunes due to hypertensive small vessel disease. Overall, stroke related to previously symptomatic internal carotid artery stenosis was not the major problem during follow-up but was largely overcome by other strokes and cardiac death.
Moyamoya disease in Taiwan.
Authors: Chen S T , Liu Y H , Hsu C Y , Hogan E L , Ryu S J
Published: June 2011

Moyamoya disease occurring in Chinese has been inadequately described. Here we report 13 cases of this disease identified by review of 3,200 cerebral angiograms performed between August 1979 and March 1986. Nine were males and four were females; there were 12 adults (aged 34-51 years) and one child (aged 11 years). All had hemorrhagic strokes with one exception, a patient with an occipital infarction. Intraventricular hemorrhage was noted by computed tomography in 10; five of these emanated from the caudate nucleus. A localized hematoma without intraventricular hemorrhage was found in two. All 13 angiograms had smokelike basal anastomoses with various degrees of stenosis or occlusion of the anterior portion of the circle of Willis; the involvement was bilateral in 12 and unilateral in one. Aneurysms were found in two patients, one in the anterior communicating artery and the other in the left anterior choroidal artery. Eleven patients recovered from the initial stroke, but two died with recurrent hemorrhage. This series differs from the series reported in Japan by the predominance of adult males. The high incidence of intraventricular hemorrhage and intracerebral hematoma is not in keeping with the previous Chinese series, in which subarachnoid hemorrhage was suspected to be the major clinical manifestation.
Diltiazem protects against functional changes in chronic cerebrovasospasm in monkeys.
Authors: Bevan R D , Bevan J A , Frazee J G
Published: June 2011

Diltiazem given 48 hours before experimental subarachnoid hemorrhage protects the cerebral vasculature of monkeys against the widespread cerebrovascular spasm seen on angiography after 5-6 days and against associated neurologic defects. In vitro examination of the cerebral arteries from treated monkeys shows that compared with untreated animals, the functional changes in the vascular smooth muscle cells, the increase in arterial wall stiffness, and the decrease in contractility, all of which were prominent in untreated monkeys, were relatively small. Other changes such as abnormal spontaneous myogenic tone, decreased responsiveness to constrictor and dilator nerve activation, and other indexes of neuronal function were little influenced by the drug. We suggest that chronic cerebrovasospasm may be initiated by the combined action of exceptionally high concentrations of a number of putative spasmogens causing injury to the larger cerebral arteries. However, the later development of intractable spasm is related to the location of blood clot and to the involvement of the vascular wall in an inflammatory process. The combined insult results in pathologic changes in the artery wall resulting in increased thickness and stiffness. Diltiazem acts on cerebrovascular smooth muscle in lower concentrations than on smooth muscle in other vascular beds, interfering with calcium entry through receptor-operated and potential-sensitive channels, and may protect against calcium-induced cell death through these and additional actions. Protection against early events presumably prevents the genesis of the subsequent chronic state.
Transient amnesia resulting from vertebral artery dissection.
Authors: Laterra J , Gebarski S , Sackellares J C
Published: June 2011

Acute transient amnesia has not been previously associated with vertebral artery dissection. We describe two men with acute onset of dense anterograde amnesia and partial retrograde amnesia resulting from spontaneous vertebral artery dissection. Both amnesic syndromes completely resolved with conservative management.
Ocular bruits in ischemic cerebrovascular disease.
Authors: Hu H H , Liao K K , Wong W J , Teng M M , Lo Y K , Chu F L , Chang T
Published: June 2011

A total of 72 ocular bruits in 50 patients with symptoms of atherothrombotic ischemic cerebrovascular disease were studied with continuous-wave Doppler ultrasonography with spectrum analysis (Dopscan). Fourteen patients also had conventional angiography, and 14 had digital subtraction angiography. Ocular bruits by augmentation flow due to occlusion (seven bruits, 9.7%) or tight stenosis (17 bruits, 23.6%) of the contralateral internal carotid artery accounted for only 24 ocular bruits (33.3%). In contrast, siphon stenosis ipsilateral to the ocular bruit was a very common finding. All 14 patients studied with conventional angiography had variable degrees of siphon stenosis ipsilateral to the ocular bruits; there was one angiography failure. We conclude that siphon stenosis can cause ocular bruit alone or can act in combination with augmentation flow by contralateral carotid occlusion or tight stenosis. The difference in their relative occurrence in our patients compared with previous reports probably reflects racial differences in the distribution of stenotic or occluded lesions of the carotid artery between our patients and Caucasian patients. The ocular bruit was the only auscultatory finding in more than a quarter of our patients (14 of 50, 28%).
Rehabilitation outcome following initial unilateral hemispheric stroke. Life table analysis approach.
Authors: Reding M J , Potes E
Published: June 2011

Life table analysis is a powerful statistical tool that has become the preferred technique for studying both the natural history of and the effect of treatment on disease outcome. We have found only one report using life table analysis to study rehabilitation outcome after stroke. We assessed the recovery of both independent ambulation and overall self-care function in 95 consecutive patients with unilateral hemispheric stroke using life table analysis. Our results support the segregation of patients into the following prognostic subgroups at the time of entry into the rehabilitation program (mean +/- SD 5 +/- 3 weeks after stroke): 1) motor deficit only, 2) motor deficit plus somatic sensory deficit, and 3) motor deficit plus somatic sensory deficit plus homonymous visual deficit. The probabilities of reaching independence in ambulation, being able to walk 150 feet with assistance, reaching independence in self-care function, and reaching a point of assisted self care (Barthel Index score of greater than or equal to 60) are highly significantly different among subgroups. The interval after stroke required to reach the plateau phase of recovery is also significantly different among subgroups. We propose that life table analysis can be used 1) to define patient outcome goals, 2) to define the time required to reach such goals, 3) to identify patients with medical or behavioral comorbidity who are functioning below their expected level, and 4) to assess the effect of alternative treatment regimens on both final outcome and time to reach that outcome.
Experimental model of symptomatic vasospasm in rabbits.
Authors: Endo S , Branson P J , Alksne J F
Published: June 2011

The common carotid arteries were ligated bilaterally 2 weeks before induction of subarachnoid hemorrhage in rabbits. The rabbits were observed closely for clinical symptoms, and angiographic and pathologic investigations were performed. Thirteen experimental rabbits showed a progressing neurologic deficit that was worst on the fourth or fifth day after the subarachnoid hemorrhage. This symptomatic change did not occur in five rabbits without previous carotid ligation. Presumably, the rabbits with carotid ligation became symptomatic because they no longer had a collateral blood flow to compensate for the reduced blood flow in the basilar artery after subarachnoid hemorrhage. Our model of symptomatic vasospasm after subarachnoid hemorrhage may be beneficial for future studies.
Transcranial Doppler measurements of the middle cerebral artery. Effect of hematocrit.
Authors: Brass L M , Pavlakis S G , DeVivo D , Piomelli S , Mohr J P
Published: June 2011

We evaluated the effects of hematocrit on blood velocity in the middle cerebral artery measured by transcranial Doppler ultrasonography in 45 patients. Hematocrits ranged from 16% to 46%, and systolic blood velocities ranged from 70 to 190 (mean 40 to 140) cm/sec. Decreases in hematocrit correlated with increases in blood velocity in the middle cerebral artery. These results suggest that transcranial Doppler measurements made in the presence of anemia may need correction.
Local anticoagulation without systemic effect using a polymer heparin delivery system.
Authors: Okada T , Bark D H , Mayberg M R
Published: June 2011

Polymeric drug delivery systems that allow the application of substances to a localized region for specified periods of time have been developed. A model for intravascular thrombosis in the rat common carotid artery was established using a combination of balloon catheter endothelial injury with 1-hour occlusion of the vessel. After endothelial injury in 11 Sprague-Dawley rats, the adventitial surface of the carotid artery was exposed to the polymer polyvinyl alcohol (PVA) containing heparin and was compared with exposure to PVA alone in the contralateral (control) vessel. Subsequent determinations of the coagulation parameters systemic prothrombin and partial thromboplastin times showed no systemic effect of heparin. All 11 control vessels demonstrated complete or partial thrombosis, whereas only one of 11 heparin/PVA-treated vessels showed a small thrombus. Morphometric analysis of the cross-sectional thrombus: lumen ratio in 10 rats showed a significant reduction (p less than 0.005) in thrombus size for treated vessels (4.1 +/- 9.6%) compared with control vessels (60.2 +/- 25.8%). Scanning electron microscopy verified the absence of thrombus in the treated vessels despite complete endothelial desquamation. In a second group of eight rats, endothelial injury without occlusion did not cause thrombosis in treated or control arteries. The coagulation parameters for this group of eight unoccluded rats were similarly unaffected by heparin/PVA treatment. Our observations suggest that a localized antithrombotic effect of heparin can be achieved without systemic anticoagulation using a polymeric drug delivery system. This technique may be applied to a variety of surgical and nonsurgical clinical conditions.
Incidence and outcome of cerebrovascular disease in Perth, Western Australia.
Authors: Ward G , Jamrozik K , Stewart-Wynne E
Published: June 2011

We estimated the event rates for stroke and transient cerebral ischemic attacks in a prospective community-based epidemiologic study in a representative segment of the city of Perth, Western Australia, during a 10-month period in 1986. Of 349 persons with an initial diagnosis of stroke or transient ischemic attack, 154 had suffered a first stroke, 75 a recurrent stroke, and 47 a transient ischemic attack; the remaining 73 persons were thought not to have had an episode of acute cerebrovascular disease. Annual event rates for first stroke (age-standardized to the "world" population) were 120 per 100,000 for males and 56 per 100,000 for females. The crude case-fatality ratio at 28 days after the index event for first stroke was 23% and varied from 0% for lacunar infarction to 57% for subarachnoid hemorrhage.
Light and electron microscopic study of lipid accumulation along margins of experimental cerebral infarcts in rats.
Authors: Kudo M , Nagayama T
Published: June 2011

Using light and electron microscopy, we studied the interaction between lipids and host tissue for up to 15 days after experimentally produced cerebral infarcts in 16 rats. A lipid-dense zone was formed along the periphery of the infarcts before a glial response started; a glycogen-rich zone appeared peripheral to the lipid zone. Macrophages and astrocytes then started to proliferate in the lipid and glycogen-rich zones. The cerebral tissue within the lipid zone underwent complete necrosis. Ultrastructurally, lipids were observed in the edematous areas as well as in various types of hematogenous and resident cells. Glycogen granules were present mainly in the astrocytic processes. Macrophages rapidly evolved into foamy macrophages in the central necrotic areas, whereas foamy transformation was not striking in the peripheral, less injured areas. Reactive fibrous astrocytes also contained varying amounts of lipids. The exact biologic significance of the lipid zone in the premacrophagic stage remains unclear; however, since lipids are hydrophobic, they may function as a barrier against edema fluid extension into the adjacent tissue.
Multicenter validation study of real-time ultrasonography, arteriography, and pathology: pathologic evaluation of carotid endarterectomy specimens.
Authors: Schenk E A , Bond M G , Aretz T H , Angelo J N , Choi H Y , Rynalski T , Gustafson N F , Berson A S , Ricotta J J , Goodison M W
Published: June 2011

The morphologic description and measurements of endarterectomy specimens are usually believed to be accurate and are used as the gold standard against which the findings of diagnostic procedures are judged. Pathology data on 289 endarterectomy specimens from five participating centers and the corresponding angiography and B-mode ultrasonography data provided a basis for scrutinizing the validity of using the morphologic measurements as a standard. Discrepancies of greater than 1 mm between pathology and angiography measurements of minimum residual lumen occurred in 35% of the cases and between pathology and B-mode ultrasonography measurements in 64% of the cases. Discrepancies of greater than 1 mm between pathology- and angiography-measured lesion width occurred in 81% of the cases and between pathology and B-mode ultrasonography measurements in 64% of the cases. The cases representing mismatches of greater than 1 mm at one participating center were subjected to a rigorous review, with remeasurement of all morphologic features, in an attempt to explain the discrepancies. Various types of artifactual distortion of the specimens, the presence of slit-like and occluded lumens that were likely related to loss of perfusion pressure, and an inability to match planes of interrogation used in angiography and B-mode ultrasonography with pathology planes contributed significantly to the existence of mismatches. On the other hand, fixation and decalcification produced minimal and insignificant distortional changes. We conclude that the acquisition of quantitative data from endarterectomy specimens and the acceptance of morphologic data as a standard are limited by a number of problems that can be defined but have been difficult to resolve.
Different sensitivity to hypoxia in neuronal activities of lateral vestibular and spinal trigeminal nuclei.
Authors: Yoshida S , Sasa M , Takaori S
Published: June 2011

Electrophysiologic studies were performed to examine the effects of hypoxia on neuronal activities of the lateral vestibular and spinal trigeminal nuclei using rats anesthetized with chloral hydrate. The rats inhaled a gas mixture of 5% oxygen and 95% nitrogen for 3.5 minutes to induce hypoxia, followed by room air. Under these conditions, mean PaO2 was decreased from 85 to 22 mm Hg 3 minutes after the start of the inhalation concomitant with a decrease in blood pressure from 108 to 55 mm Hg. There were no significant differences in these variables between rats used for vestibular nucleus experiments and rats used for trigeminal nucleus experiments. In the lateral vestibular nucleus, hypoxia inhibited postsynaptic components of the evoked field potential, spike generation of monosynaptic neurons on vestibular nerve stimulation, and firing induced by iontophoretic application of glutamate. In the spinal trigeminal nucleus, however, there were no alterations of the field potential or spike generation of the neurons on trigeminal nerve stimulation. These results indicate that the lateral vestibular nucleus neurons are much more sensitive to hypoxia than the spinal trigeminal nucleus neurons. The failure of transmission in the monosynaptic neurons of the lateral vestibular nucleus is suggested to be due to the inhibition of excitability of the postsynaptic membrane.
Effect of nimodipine on blood pressure in acute ischemic stroke in humans.
Authors: Fagan S C , Gengo F M , Bates V , Levine S R , Kinkel W R
Published: June 2011

Nimodipine is currently under investigation for the treatment of acute stroke. Although relatively specific for the cerebrovasculature, acute reductions in blood pressure after a dose may adversely affect neurologic outcome. We studied 29 consecutive acute ischemic stroke patients treated with placebo (n = 9) or either 120 (n = 10) or 240 (n = 10) mg/day of nimodipine. Blood pressure was recorded before and 30 and 60 minutes after a dose for the first 8 days. Ten neurologic physicians were asked to predict the treatment group (placebo or drug) of randomly selected patients based on blood pressure results. Only those patients on 240 mg/day of nimodipine had significant decreases in blood pressure after a dose (p less than 0.001); however, these were minimal (average 10 mm Hg systolic). Only 26 of 48 treatment predictions (54%) were correct. At the studied doses, nimodipine has a minimal effect on blood pressure in the acute stroke period.
Antiplatelet agents in the secondary prevention of stroke: meta-analysis of the randomized control trials.
Authors: Sze P C , Reitman D , Pincus M M , Sacks H S , Chalmers T C
Published: June 2011

Randomized control trials of antiplatelet agents in the prevention of stroke following transient ischemic attacks have had conflicting results. The decision to employ aspirin instead of placebo as the control regimen in trials testing newer antiplatelet agents emphasizes the need for an accurate estimate of the efficacy of older drugs. A meta-analysis of seven randomized control trials comparing aspirin and/or sulfinpyrazone or dipyridamole with placebo was performed. For aspirin compared with placebo, a nonsignificant reduction in stroke of 15% (odds ratio 0.85, 95% confidence interval 0.60-1.19; chi 2 = 0.78, p greater than 0.30) was found. For aspirin combined with sulfinpyrazone or dipyridamole compared with placebo, a 39% reduction in stroke was observed (odds ratio 0.61, 95% confidence interval 0.39-0.95; chi 2 = 4.22, p less than 0.05); at the same time a 350% increase in gastrointestinal hemorrhage or peptic ulcer was noted (odds ratio 3.5, 95% confidence interval 1.26-9.75; chi 2 = 4.61, p less than 0.05). A trend in reduction of strokes for men was observed (odds ratio 0.58, 95% confidence interval 0.32-1.07; chi 2 = 2.52, p less than 0.15) for any regimen containing aspirin. The significant benefit of aspirin-combination therapy on stroke must be interpreted cautiously because of a number of possible biases. It is still conceivable that aspirin alone may decrease the incidence of stroke by as much as 40%, but a sample of greater than 13,000 patients would be needed to confirm the benefit observed in our analysis.
Endothelium-dependent contractions to calcium ionophore A23187, arachidonic acid, and acetylcholine in canine basilar arteries.
Authors: Katusic Z S , Shepherd J T , Vanhoutte P M
Published: June 2011

The effects of the calcium ionophore A23187, arachidonic acid, and acetylcholine were studied in isolated canine basilar arteries. Rings with and without endothelium were suspended for isometric tension recording in physiological saline. In unstimulated rings, A23187, arachidonic acid, and acetylcholine caused endothelium-dependent contractions. The contractions of rings caused by uridine 5'-triphosphate were not affected by removal of the endothelium. An inhibitor of cyclooxygenase, indomethacin (10(-5) M), prevented excitatory responses to A23187, arachidonic acid, and acetylcholine but did not alter contractions caused by KCl. An inhibitor of thromboxane synthetase, dazoxiben (10(-4) M), significantly reduced endothelium-dependent contractions to A23187 and arachidonic acid but did not significantly affect contractions caused by acetylcholine. These results demonstrate that A23187, arachidonic acid, and acetylcholine cause excitatory endothelium-dependent responses in canine cerebral blood vessels by increasing the release of product(s) of cyclooxygenase from endothelial cells; in the case of A23187 and arachidonic acid, thromboxane A2 contributes to the endothelium-dependent contractions.
Inhibitory effect of acetylsalicylic acid on platelet function in patients with completed stroke or reversible ischemic neurologic deficit.
Authors: Lee T K , Chen Y C , Lien I N , Liu M C , Huang Z S
Published: June 2011

The purpose of our study was to investigate the effects of different doses of acetylsalicylic acid on platelet aggregation. Among inpatients of the National Taiwan University Hospital, 236 cases of completed stroke and seven cases of reversible ischemic neurologic deficit that were diagnosed by computed tomography of the brain and that had not ingested acetylsalicylic acid or acetylsalicylic acidlike drugs for greater than 2 weeks before admission were selected for this study. Thromboxane B2 and 6-keto-PGF1 alpha were measured by radioimmunoassay, threshold concentration of adenosine diphosphate was measured by Born's method, and circulating platelet aggregates were measured by the method of Wu and Hoak. Various single doses of acetylsalicylic acid (75, 300, or 600 mg) or 300 mg acetylsalicylic acid every 6 hours for four doses or one dose of 300 mg acetylsalicylic acid with 75 mg dipyridamole significantly suppressed the mean plasma thromboxane B2 concentrations and elevated the mean adenosine diphosphate threshold concentrations. Abnormal plasma thromboxane B2 concentrations, adenosine diphosphate threshold concentrations, or circulating platelet aggregate ratios were significantly normalized after administration of these regimens. The effects were not significantly different among treatment groups. Forty milligrams of acetylsalicylic acid seemed to have less platelet-inhibitory effect. A single dose of 75 mg acetylsalicylic acid significantly inhibited platelet hyperfunction and effectively corrected the abnormal plasma thromboxane B2 concentrations, adenosine diphosphate threshold concentrations, and circulating platelet aggregate ratios. Higher doses did not enhance the inhibitory effect. In addition, this single dose of acetylsalicylic acid did not significantly suppress plasma 6-keto-PGF1 alpha. We conclude that 75 mg acetylsalicylic acid per day is adequate to inhibit platelet hyperfunction.
Metabolic changes during experimental cerebral ischemia in hyperglycemic rats, observed by 31P and 1H magnetic resonance spectroscopy.
Authors: Bolas N M , Rajagopalan B , Mitsumori F , Radda G K
Published: June 2011

Progressive cerebral ischemia was induced in seven anesthetized hyperglycemic rats by carotid artery ligation and hemorrhagic hypotension. Phosphorus metabolites, intracellular pH, and lactate in the brain were monitored by 31P and 1H magnetic resonance spectroscopy. Under conditions in which blood flow was low, phosphocreatine (PCr) concentration and intracellular pH decreased and the concentration of lactate increased. The decrease in ATP was approximately one-third that of PCr until only 25% PCr remained, after which ATP was lost more rapidly than PCr. These changes were interpreted in terms of three regions observed by the magnetic resonance coil, one of complete ischemia, one of partial ischemia, and one of perfusion sufficient to maintain normal metabolite levels. The extent of the three regions was estimated quantitatively. Broadening and splitting of the inorganic phosphorus (Pi) peak into two components provided further evidence of distinct populations of cells, one very acidic and another less so. Apparent intracellular buffering capacity was calculated as 23.6 +/- 1.3 mumol lactate/g wet wt/pH.
Cardioembolic stroke from atrial septal aneurysm.
Authors: Di Pasquale G , Andreoli A , Grazi P , Dominici P , Pinelli G
Published: June 2011

Atrial septal aneurysm is an uncommon occult cardiac source of cerebral embolism. It is usually asymptomatic, and clinical cardiologic examination and electrocardiography fail to reveal its presence. We report a case of a 34-year-old woman with sudden right hemiplegia and aphasia from occlusion of the left carotid siphon in whom an atrial septal aneurysm was detected by two-dimensional echocardiography. The absence of atherosclerotic risk factors and vascular lesions proximal to the carotid occlusion strengthened a causal relation between atrial septal aneurysm and cerebral infarction. Consequently, two-dimensional echocardiography may be advisable in every patient with unexplained ischemic stroke to detect possible occult embolic cardiac abnormalities.
Computed tomography of the cervical carotid artery: significance of the lucent defect.
Authors: Culebras A , Magaña R , Cacayorin E D
Published: June 2011

To investigate the clinical significance of lucent defects in computed tomography (CT) scans of the cervical carotid artery plaque, we studied 95 patients with recent symptoms of hemispheric ischemia. Using multiple linear regression analysis, we estimated the strength of the association of symptoms with laterality of carotid artery lucent lesions, stenoses, and ulcerations observed in CT scans. Hemispheric symptoms correlated strongly with ipsilateral carotid lucent lesions (partial p less than 0.025) and with ipsilateral severe (greater than 75%) carotid stenosis (partial p less than 0.025). Carotid artery ulcerations had a weaker association (partial p less than 0.1), and stenoses of mild and moderate degrees showed none. The overall performance of all three plaque complications was highly significant (p less than 0.005). The lucent defect indicates a morphologic change in the carotid plaque that plays an important role in the development of symptoms of hemispheric ischemia. This is in agreement with the notion that the lucent defect is the image of intraplaque hemorrhage and/or necrosis, which are complications central to the development of symptomatic carotid disease.
Effect of autologous clot embolism on regional protein biosynthesis of monkey brain.
Authors: Xie Y , Munekata K , Seo K , Hossmann K A
Published: June 2011

Focal cerebral ischemia was produced in monkeys by injection of autologous clots into the left internal carotid artery. Regional protein synthesis was studied 2 hours after embolism by autoradiographic and biochemical evaluation of [3H]phenylalanine incorporation into brain proteins, and the results were correlated with electrophysiologic (electroencephalogram, evoked potentials) and light microscopic observations. Ischemic territories were clearly identified on autoradiograms as sharply demarcated areas with reduced radioactivity. The localization of regions with reduced protein biosynthesis correlated with the early postembolic suppression of evoked potentials but not with the (improved) functional state and the morphologic alterations at the end of the experiment. Suppression of amino acid incorporation, in consequence, is a long-lasting event that allows documentation of the initial embolic impact for at least 2 hours irrespective of the subsequent recovery process.
Identification of recent lacunar lesions in cases of multiple small infarctions by magnetic resonance imaging.
Authors: Miyashita K , Naritomi H , Sawada T , Nakamura M , Kuriyama Y , Ogawa M , Imakita S
Published: June 2011

In nine patients with recent lacunar stroke who revealed multiple small lesions in x-ray computed tomography (CT) and magnetic resonance imaging (MRI), CT and MRI enhancement studies were performed on the same day employing iodinated contrast medium and gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), respectively. In CT, the injection of contrast medium enhanced recent lesions in only four of the nine patients; furthermore, the effect was weak. In MRI, the injection of Gd-DTPA enhanced recent lesions in all patients except for one who was examined 4 weeks after ictus, and the effect was excellent. Recent infarcts could be identified only by Gd-DTPA-enhanced MRI in four of the nine patients. In patients with multiple small infarctions, identification of recent small infarcted lesions by CT or MRI is sometimes difficult; however, the use of Gd-DTPA in MRI makes it possible to distinguish recent infarcts from other lesions definitively.
Pulsed multigated Doppler ultrasonography in the diagnosis of carotid artery disease.
Authors: Sillesen H , Bitsch K R , Schroeder T , Steenberg H J , Hansen L , Hansen H J
Published: June 2011

To evaluate the accuracy of a pulsed multigated Doppler system, 128 carotid arteries were examined. The spectral broadening index was calculated from the power spectrum of a small sample volume located in the center of the stream according to the flow profile and was related to the degree of stenosis as determined by contrast angiography. Even minor wall irregularities seen on the angiogram were classified as disease. The ability of the system to discriminate between normal and diseased vessels reached a sensitivity of 94% and a specificity of 91%. Classification of greater than 50% or less than 50% stenosis could be performed with a sensitivity of 90% and a specificity of 85%. Pulsed multigated Doppler ultrasonography allows identification of even minor degrees of stenosis of the carotid artery and provides an alternative to duplex scanning. Furthermore, the blood flow profile provided by a multigated Doppler system may add valuable information concerning blood flow characteristics not obtainable by single-gated systems.
Effects of calcium channel blockers on neurologic outcome after focal ischemia in rabbits.
Authors: Lyden P D , Zivin J A , Kochhar A , Mazzarella V
Published: June 2011

To determine the efficacy of calcium channel blockers in preserving neurologic function after central nervous system ischemia, we studied three such agents in two animal models. We treated rabbits after inducing ischemia in the brain with intra-arterial microspheres and in the spinal cord using a removable aortic occluding device. We found no benefit, in terms of neurologic functional outcome, from lidoflazine, nimodipine, or nicardipine. All three agents elevated regional blood flow in the spinal cord. We conclude that calcium antagonists are not likely to prove beneficial if used alone in the treatment of focal central nervous system ischemia.
Transcranial Doppler ultrasonography of carotid-basilar collateral circulation in subclavian steal.
Authors: Klingelhöfer J , Conrad B , Benecke R , Frank B
Published: June 2011

The combination of a carotid-basilar and a vertebro-vertebral collateral circulation was verified directly in a patient with a complete subclavian steal by means of transcranial Doppler ultrasonography. The patient showed permanently reversed blood flow in the basilar artery. The subclavian steal influenced the hemodynamics of the circle of Willis at rest and during functional tests of the collaterally supplied arm. Our investigation provides the first direct experimental evidence of increased blood flow velocity in the carotid artery after decompressing the collaterally supplied arm.
Influence of liver dysfunction on volume of putaminal hemorrhage.
Authors: Niizuma H , Shimizu Y , Nakasato N , Jokura H , Suzuki J
Published: June 2011

We studied the relations of age, sex, hypertension, alcohol consumption, liver dysfunction, and thrombocyte count to the volume of the hematoma in 141 patients with spontaneous putaminal hemorrhage. Hematomas were significantly larger in men, regular alcohol consumers, those with liver dysfunction, and those with low platelet counts. Our findings reflect the fact that almost all of the alcohol consumers were men, most of them had liver disorders, and the volume of hematoma in such patients was relatively large.
21-Aminosteroid lipid peroxidation inhibitor U74006F protects against cerebral ischemia in gerbils.
Authors: Hall E D , Pazara K E , Braughler J M
Published: June 2011

U74006F (21-[4-(2,6-di-1-pyrrolidinyl-4-pyrimidinyl)-1-piperazinyl]-16 alpha-methylpregna-1,4,9(11)-triene-3,20-dione, monomethane sulfonate) is a novel and potent inhibitor of central nervous system tissue lipid peroxidation that is devoid of classical steroid hormonal activities. Its possible efficacy in attenuating postischemic mortality and neuronal necrosis was examined in gerbils following 3-hour unilateral carotid artery occlusion. Male Mongolian gerbils received two intraperitoneal injections of either vehicle or U74006F (3 or 10 mg/kg), the first injection 10 minutes before and the second injection at the end of the 3-hour ischemic episode. In an initial series of experiments, vehicle-treated gerbils displayed 60.9% (14 of 23) survival 24 hours after ischemia, which decreased to 34.8% (8 of 23) at 48 hours. In contrast, the 10 mg/kg U74006F-treated group showed 86.7% (13 of 15) survival at 24 hours (p less than 0.15 vs. vehicle) and 80.0% (12 of 15) survival at 48 hours (p less than 0.02). In a second series, neurons in the hippocampal CA1 subfield and the medial and lateral cerebral cortex were counted in gerbils surviving 24 hours after unilateral carotid artery occlusion. Comparison of neuronal densities in the ischemic hemisphere with those in the contralateral nonischemic hemisphere revealed significant neuronal preservation in all three brain regions of 10 mg/kg i.p. x 2 U74006F-treated gerbils. Our results show that U74006F can improve survival and attenuate neuronal necrosis in a severe brain ischemia model.(ABSTRACT TRUNCATED AT 250 WORDS)
Risk of brain infarction in familial hypercholesterolemia.
Authors: Kaste M , Koivisto P
Published: June 2011

We followed 54 subjects with heterozygous familial hypercholesterolemia for an average of 10 (range 3-14) years. Half were treated surgically with partial ileal bypass and the other half (matched for age, sex, coronary heart disease, blood pressure, diabetes mellitus, smoking, obesity, and serum cholesterol concentration) were treated conservatively with diet and hypolipidemic drugs. The mean decrease in serum cholesterol concentration from the average value of 522 mg/dl on entry into the study was 32% in the surgically treated group and 10% in the conservatively treated group. One quarter of the subjects (14 of 54) had symptomatic cerebrovascular disorders and one tenth (six of 54) suffered a brain infarction at a mean age of 43 (range 30-57) years. Two thirds of the brain infarctions occurred during follow-up. The method of treatment of familial hypercholesterolemia did not affect the number of new cerebrovascular events. The incidence of brain infarction was 7.4/1000/yr. The risk of brain infarction in these subjects with familial hypercholesterolemia was at least 20 times higher than in the general population. We conclude that symptomatic subjects with familial hypercholesterolemia have not only a high risk of coronary heart disease but also a high risk of cerebrovascular disorders.
Abnormalities of interictal cerebral perfusion in classic but not common migraine.
Authors: Lagrèze H L , Dettmers C , Hartmann A
Published: June 2011

Regional cerebral blood flow (rCBF) was measured as gray matter blood flow using the 133Xe inhalation technique in 50 pain-free headache patients: Eight patients having classic migraine with normal computed tomograms were matched to patients having common migraine and to normal controls. Interictal rCBF was determined at least 6 days after the last migraine attack and more than 24 hours before the next one. There were no between-group differences for age, PCO2, mean hemispheric blood flow, interindividual and intraindividual variabilities, hyperfrontality, or rCBF symmetry. However, when subjects were classified as to overall abnormal perfusion, a significant number (n = 4, p less than 0.04) of patients with classic migraine had rCBF abnormalities, whereas only one such patient was seen in the group with common migraine. Patients with classic migraine had abnormal mean hemispheric blood flows or disturbed intrahemispheric rCBF patterns. Oligemic and hyperemic regions topographically corresponded to the clinical symptoms in one patient. We conclude that during migraine attacks and interictally there is an instability of rCBF control in patients with classic but not common migraine.
Cyclohexyl adenosine protects against neuronal death following ischemia in the CA1 region of gerbil hippocampus.
Authors: von Lubitz D K , Dambrosia J M , Kempski O , Redmond D J
Published: June 2011

Sixty-five male gerbils were exposed to 30 minutes of cerebral ischemia induced by a bilateral carotid artery occlusion. One group of 15 gerbils received a single injection of 25 microliter of 5 microM cyclohexyladenosine into the cerebral ventricle 15 minutes after release of the occlusion. Another group of 45 gerbils received a similar injection of the vehicle. Five days after ischemia, the hippocampal histology was examined under light microscopy. In the gerbils treated with the adenosine receptor agonist N-6-cyclohexyladenosine, the CA1 region of the hippocampus showed significant quantitative pyramidal cell preservation (p less than 0.01, Mann-Whitney U test). Qualitatively, substantial destruction of CA1 neurons was present in all hippocampi of the vehicle-injected gerbils. The CA1 neurons in the cyclohexyladenosine-treated gerbils did not differ from those seen in the five nonischemic controls. The precise mechanism of the protective action of cyclohexyladenosine is unknown, although it has been demonstrated that adenosine agonists reduce presynaptic glutamate release in vitro. It is possible that postischemic administration of cyclohexyladenosine decreases the release of this neurotransmitter in the intact brain as well. The concomitant reduction of the neurotoxic effect of glutamate may, therefore, result in better histologic preservation of the pyramidal cells in the postischemic CA1.
Embolic stroke from cardiac papillary fibroelastomas.
Authors: Kasarskis E J , O'Connor W , Earle G
Published: June 2011

We describe two patients with cerebral emboli originating from a cardiac papillary fibroelastoma and compared them with six patients reported in the literature. Surgical excision was curative in both of our patients. The surface topography of the tumor, as visualized by scanning electron microscopy, is described.
Episodic Central Nervous System Ischemia of Undetermined Cause: Relation to Occult Left Atrial Myxoma
Authors: YARNELL PHILIP R. , SPANN JAMES F. , DOUGHERTY JOCELYN , MASON DEAN T.
Published: June 2011

Left atrial myxoma should be considered seriously in patients with unexplained cerebral dysfunction, particularly those in whom there are multiple recurrent cerebral vascular episodes, despite the absence of suggestive heart findings. Substantiating this observation are two such illustrative cases with embolic disease leading to neurological involvement who otherwise lacked cardiac symptomatology and did not exhibit auscultatory, roentgenological or electrocardiographical evidence of heart disease. The first patient died without antemortem recognition of the tumor and, in the second, the myxoma was removed after eventual identification by cardiac angiography and histological examination of embolic material. Thus, it is recommended that left atrial myxoma be definitely sought by heart catheterization with contrast study as a potentially curable cause of chronic nervous system disease with transient episodes of vascular insufficiency even in patients without cardiac manifestations.