bluuebunny/crossref_metadata_2025 huggingface dataset:
A randomized controlled trial of hemodilution therapy in acute ischemic stroke.
Authors: Strand T , Asplund K , Eriksson S , Hägg E , Lithner F , Wester P O
Published: June 2011

Rapid hemodilution in the early phase of ischemic stroke by the combination of venesection (250-650 ml during the first 2 days) and administration of low-molecular weight dextran was evaluated in a prospective controlled trial. Fifty-two patients were randomized to hemodilution therapy and 50 to a control group; the two groups were comparable in important prognostic variables. Mean hemoglobin was reduced from 147 to 127 g/l, hematocrit from 43 to 37% and, in a subsample of patients, whole-blood viscosity at a shear rate of 23 sec-1 from 7.0 to 4.3 cps over the first 2 days. Hemodilution was then maintained by repeated dextran infusions. Of the hemodiluted patients, 85% improved in neurological scoring over the first 10 days as compared to 64% of the control patients (p less than 0.025). The case fatality rate during the first 3 months was little affected by hemodilution. Among the survivors, 8% of the hemodiluted and 31% of the non-hemodiluted patients were unable to walk at 3 months. The proportion of surviving patients still hospitalized at the 3-month follow-up was 13% in the hemodilution group and 39% in the control group (p less than 0.01). The combination of venesection and dextran 40 administration is thus an unsophisticated but effective way to achieve rapid hemodilution in patients with acute cerebral infarction, and it improves the overall clinical outcome over the first 3 months.
No intracerebral steal phenomenon in the ischemic brain following papaverine administration.
Authors: Gogolak I , Gotoh F , Tomita M , Tanahashi N , Kobari M , Shinohara T , Mihara B
Published: June 2011

The steal phenomenon due to a vasodilator was investigated in 6 cats in which cerebral ischemia had been produced by left middle cerebral artery (MCA) occlusion. The photoelectric method was employed for continuous recording of the cerebral blood volume together with frequent determinations of the cerebral blood flow (CBF) through the ischemic cerebral tissue at the following four stages: before MCA occlusion, 2 hours after MCA occlusion before the injection of papaverine, after the injection of papaverine, and when the systemic arterial blood pressure (SABP) was adjusted non-pharmacologically to the control level using a "vasculator". The administration of the vasodilator produced conflicting results for the CBF changes in the ischemic area with a decrease in SABP as reported previously in the literature. However, when the SABP was corrected to the control level, the CBF in the ischemic region became increased in all 6 cases to above the control ischemic flow values. It is concluded that the decreased CBF in the ischemic tissue after vasodilator administration was not due to the steal phenomenon, but simply to a fall in SABP.
The incidence of stroke in the Kuopio area of East Finland.
Authors: Sivenius J , Heinonen O P , Pyörälä K , Salonen J , Riekkinen P
Published: June 2011

During a 20-month study period there were 373 strokes in a geographically defined population (235/100,000/year). When age and sex were adjusted to the mean population of Finland in 1979, the annual incidence of stroke was 270/100,000 persons. The distribution of incident cases by diagnostic category was as follows: cerebral infarction 80%, ICH 9%, SAH 8% and NOS 3%. Case fatality of stroke within one year was 37%. The recurrence rate was 6% during the first year after any stroke.
A histochemical study of cerebral cortical vessels and ganglionic vessels of the caudatoputamen in aging normotensive rats.
Authors: Rieke G K , Cannon M S
Published: June 2011

The goal was to describe the metabolic profile of ganglionic and cortical arteries and arterioles in aging normotensive male rats. Five enzymes indicative of key metabolic pathways in the vessel walls were semiquantitatively evaluated using bright-field histochemical microscopy. Lactate dehydrogenase showed significant reactivity which increased with vessel diameter in cortical and ganglionic vessels in all age groups tested. Succinate dehydrogenase and cytochrome oxidase showed little reactivity in both cortical and ganglionic vessels, suggesting a reduced role for aerobic metabolic pathways. Myosin ATPase reactivity was high in cortical and ganglionic vessels. Only this enzyme showed an increased reactivity that was correlated with the age and diameter of the vessel. Glucose-6-phosphate dehydrogenase reactivity was more pronounced in cortical than ganglionic vessels, suggesting that the hexose-monophosphate-shunt may be more active in the cortical vessels. There were no regional differences in enzyme reactivity throughout the caudatoputamen. In conclusion, both the cortical and ganglionic vessels are metabolically active, with significant anaerobic glycolysis, and reduced, but observable capacity for aerobic metabolism. The decreased myosin ATPase reactivity and the low level of glucose-6-phosphate dehydrogenase reactivity in the ganglionic arterioles of senescent rats may contribute to the susceptibility of these vessels to cerebrovascular accidents.
Pressor response to electrical and chemical stimulation of nucleus raphe dorsalis in the cat.
Authors: Piper R D , Goadsby P J
Published: June 2011

The dorsal raphe nucleus was stimulated electrically and chemically in 57 cats with blood pressure being measured by an arterial catheter. Blood pressure rose by a mean of 119.5 +/- 8.9% on stimulation of the dorsal raphe nucleus at a frequency of 200 sec-1. This pressor response was frequency-dependent over the range 0.2 to 200 sec-1 and the site of origin was localized to the dorsal raphe nucleus. The pressor response could also be obtained by the injection of D,L-homocysteic acid into the nucleus, and is therefore likely to be due to activation of cell bodies rather than axons of passage. The response was blocked by high spinal cord section but was not affected by bilateral clamping of the adrenal glands or supracollicular decerebration. The pressor response was significantly reduced by pretreatment of the cats with parachlorophenylalanine (PCPA) and abolished by the alpha receptor blocker phentolamine, suggesting that both serotonergic and noradrenergic synapses are involved.
Dietary and other risk factors for stroke in Hawaiian Japanese men.
Authors: Kagan A , Popper J S , Rhoads G G , Yano K
Published: June 2011

As part of an on-going longitudinal study, 7895 men of Japanese ancestry living on the island of Oahu, aged 45-68 and free of evidence of prior stroke at entry examination, have been followed by re-examinations and surveillance. During ten years of follow-up 154 men developed thromboembolic stroke, 65 developed intracranial hemorrhage, and 19 developed stroke of unknown type. There were 79 deaths attributed to stroke. The independent risk factors for thrombo-embolic stroke were elevated blood pressure, glucose intolerance, age, electrocardiographic evidence of left ventricular hypertrophy or strain, cigarette smoking and proteinuria. Attributes associated with increased risk of intracranial hemorrhage were age, elevated blood pressure, cigarette smoking, serum uric acid and, inversely, serum cholesterol level. Electrocardiographic evidence of left ventricular hypertrophy or strain significantly increased the risk of cerebral hemorrhage, but was not associated with subarachnoid hemorrhage. In univariate analysis, there was an inverse relation between dietary fat intake and thrombo-embolic and total stroke incidence. An inverse relation was also shown between protein intake and total stroke incidence. These dietary relations became statistically not significant in multivariate analysis. No relation was found between salt intake and the incidence of stroke.
Isolation of speech area from focal brain ischemia.
Authors: Bogousslavsky J , Regli F , Assal G
Published: June 2011

A patient with atrial fibrillation and internal carotid artery occlusion developed mixed transcortical aphasia. The CT scan showed two recent distinct infarcts in the dominant hemisphere, one in the precentral artery area (pial artery infarct) and one in the borderzone area between the posterior and middle cerebral arteries territories (watershed infarct). The perisylvian speech areas were spared, but probably disconnected from other areas by the infarcts. The syndrome of isolation of speech area may be caused by vascular conditions which are able to produce simultaneous pial artery and watershed infarcts, and is not necessarily related to more extensive processes of the brain.
Lacunar syndrome due to intracerebral hemorrhage.
Authors: Mori E , Tabuchi M , Yamadori A
Published: June 2011

It has been recognized that small intracerebral hemorrhage not uncommonly produced lacunar syndromes. In this study, we examined cases of intracerebral hemorrhage presenting as lacunar syndromes. Of 174 cases with recent intracerebral hemorrhage, 19 presented with a lacunar syndrome: 4 presented with pure motor hemiparesis, 5, ataxic hemiparesis, 3, dysarthria-clumsy hand syndrome, 7, sensorimotor stroke, and, none, pure sensory stroke. The sites of hemorrhage were capsular in 11, putamenal in 6, and pontine in 2. In these 19 patients, 17 were hypertensive, and the signs characteristic of parenchymal hemorrhage, e.g., gradual onset, headache, nausea, vomiting and stiff neck, were absent or very rare. Computed tomography revealed that one third of the patients had one or more non-symptomatic lacunae in the basal ganglia, the corona radiata or the anterior limb of the internal capsule. These observations suggests that hypertensive intracerebral hemorrhage causes lacunar syndrome more often than previously considered and is apt to manifest ataxic hemiparesis and sensorimotor stroke. Computed tomography is the only way of differentiating hemorrhagic "lacunar" syndrome from lacunar infarct.
Pharmacological comparison of isolated monkey and dog cerebral arteries.
Authors: Sasaki T , Kassell N F , Torner J C , Maixner W , Turner D M
Published: June 2011

Pharmacological differences between canine and monkey basilar arteries were studied in vitro. The constrictor response of canine basilar artery to either norepinephrine or an alpha 1-adrenoceptor agonist phenylephrine was partly inhibited by an alpha 2-adrenoceptor antagonist yohimbine but not by an alpha 1-adrenoceptor antagonist prazosin. The contraction elicited by an alpha 2-adrenoceptor agonist clonidine was inhibited by neither prazosin nor yohimbine. These results suggest that the receptors in canine basilar artery which mediate norepinephrine-induced contraction are different from classical alpha 1 or alpha 2-adrenoceptors, although they more closely resemble the alpha 2- rather than the alpha 1-subtype. Using monkey basilar artery, phenylephrine produced the same amplitude of maximum contractile response as norepinephrine, though a much higher concentration of phenylephrine than norepinephrine was needed in order to elicit that maximum response. Clonidine did not elicit contractions. The contraction induced by norepinephrine was markedly suppressed by both prazosin and yohimbine in a noncompetitive fashion. The constrictor response of monkey basilar artery to norepinephrine, therefore, appears to be mediated by alpha 1-like adrenoceptors. Comparison of ED50 values for thromboxane A2 revealed that the monkey basilar artery was more sensitive to thromboxane A2 than that of the canine. Prostaglandin F2 alpha produced a larger maximum contraction in monkey basilar arteries than in canine basilar arteries, although the ED50 values for monkey basilar arteries were larger than those for canine basilar arteries. The ED50 values for serotonin in canine basilar arteries were a little less than those for monkey basilar arteries, although both arteries produced nearly identical maximum contractions.
Simultaneous rupture of two intracranial aneurysms: CT diagnosis.
Authors: Joslyn J N , Williams J P , White J L , White R L
Published: June 2011

A case of simultaneous rupture of two intracranial aneurysms is reported. This is a rare event, and we found no CT reports of such a case. This case points out that the usual assumption of a single aneurysm rupture in a patient with multiple aneurysms may be erroneous and difficult to diagnose angiographically, but may lend itself to CT diagnosis.
Primary thrombocythemia in a patient with cerebellar infarction.
Authors: Delangre T , Mihout B , Borh J Y , Samson M
Published: June 2011

A patient suffering from essential thrombocythemia presented manifestations of digital thromboses and two cerebral ischemic strokes. Anomalies of platelet function are discussed in relation to published data and the efficacy of antiaggregant treatment is stressed.
Blood flow and the localization of atherosclerotic plaques.
Authors: McMillan D E
Published: June 2011

Saphenous veins used in aortocoronary bypass procedures slowly narrow. The narrowing and atherosclerosis appear to develop in reaction to the new flow conditions present in the saphenous veins. Localization of atherosclerosis in the arterial system also suggests that local flow conditions play a role in atherogenesis; plaques are characteristically found in regions of separated flow. The pattern of separated flow in arteries is influenced by the pulsatility of arterial flow. Stagnation points delimiting flow separations migrate with each systole. An additional motion of blood, angular momentum, produces a corkscrew component to the flow. This added rotary component generates a stress that combines with the stress generated by to and fro motion of stagnation points to produce an area of multidirectional shear stress in the stagnation region. The rapidly reorienting shear stress places a special burden on the region's endothelial cells, producing an area of non-elongated cells, compromising cell internal fluidity, and modifying adhesion to neighboring cells to increase local permeability. The amount of multi-directional force generated in regions of multi-directional shear stress is increased by the flow properties of blood. Studies of blood, particularly in diabetes, will be able to characterize the factors that control the magnitude of permeability-enhancing multi-directional stress and suggest new ways to slow atherogenesis and ultimately prevent atherosclerosis.
Comparison of ultrasound and IV-DSA for carotid evaluation.
Authors: Zwiebel W J , Strother C M , Austin C W , Sackett J F
Published: June 2011

Sixty carotid bifurcations in 34 symptomatic patients were examined prospectively with ultrasound (continuous wave Doppler and high resolution, B-mode imaging) and intravenous digital subtraction angiography (IV-DSA). The overall quality of examination was better with DSA than with ultrasound. Imaging of the external carotid artery was particularly difficult with sonography. For evaluation of the common and internal carotid arteries, eight percent of IV-DSA studies were poor or inadequate as compared with 12% for B-mode imaging. Overall for detection of atherosclerotic plaque, high resolution B-mode sonography was 84% sensitive and DSA 81% sensitive. When only the common and internal carotid arteries were considered, the sensitivity of high resolution sonography improved to 93% and the sensitivity of IV-DSA increased to 86%. Ultrasound (combined high resolution, B-mode sonography and CW Doppler) correctly identified all six internal carotid occlusions in the series. While IV-DSA correctly identified five of the six occlusions, the sensitivity for detection of lesions causing 70% or more stenosis was 95% for both ultrasound and IV-DSA. Sensitivity for 50% or greater obstruction was 79% for ultrasound and 85% for IV-DSA. Ultrasound sensitivity for greater than 50.9% stenoses rose to 87% when only the common and internal carotid were considered while IV-DSA sensitivity remained at 85%. Specificity was good at all levels of obstruction. It may be concluded from this study that the accuracy of ultrasound and IV-DSA are quite similar for evaluation of the carotid bifurcation and that either test is a satisfactory screening method for carotid bifurcation atheromatous disease.
Carotid atherosclerosis in familial hypercholesterolemia.
Authors: Postiglione A , Rubba P , De Simone B , Patti L , Cicerano U , Mancini M
Published: June 2011

Common and internal carotids have been studied by noninvasive method (echo-Doppler) in 30 normotensive patients with familial hypercholesterolemia (FH). Vascular lesions were detected in 14 patients (46%), who presented one or more lesions of different degree (between 1-15% and 16-49%). In one case, only one carotid had stenosis greater than 50%. Severity and number of stenosis were related to age and levels of hypercholesterolemia. FH patients with carotid lesions showed a significantly higher LDL-cholesterol (p less than 0.01) and plasma apolipoprotein B (p less than 0.001) concentrations and a significantly lower HDL-cholesterol (p less than 0.05) and plasma apolipoprotein A (p less than 0.001) levels as compared to those with normal echo-Doppler findings. These data indicate that investigation of arterial districts other than coronaries are useful in quantitative evaluation of atherosclerotic involvement.
A double-blind, placebo-controlled trial of fish oil concentrate (MaxEpa) in stroke patients.
Authors: Green D , Barreres L , Borensztajn J , Kaplan P , Reddy M N , Rovner R , Simon H
Published: June 2011

The feeding of large amounts of fish or fish oils to healthy volunteers has been shown to reduce plasma triglycerides and platelet aggregation, and prolong the skin bleeding time. To determine whether a commercially available marine oil (MaxEpa) would have similar effect in stroke patients, we performed a double-blind, placebo-controlled study in 11 patients (7 men, 4 women) with completed stroke (7) or transient ischemic attacks (TIA's) (4). Ten 1 ml opaque capsules containing either MaxEpa or olive oil were given daily for 6 weeks, and then the patients were crossed-over. Aspirin was avoided during the trial. The data were analyzed by paired-sample t-tests. A significant reduction was found in serum triglycerides, but total serum cholesterol and HDL cholesterol were unaffected. The bleeding time was modestly prolonged after 3 weeks of treatment, but the differences between MaxEpa and olive oil treatments were not significant at 6 weeks. Aside from an increase in collagen-stimulated malondialdehyde formation no other statistically significant changes in hemostatic factors were observed. We conclude that the ingestion of up to 10 MaxEpa capsules daily for 6 weeks has little influence on such established risk factors as cholesterol concentration and platelet function in patients with stroke or TIA's.
Stroke-in-progression.
Authors: Gautier J C
Published: June 2011

Stroke-in-progression or stroke-in-evolution or progressing stroke is a clinical entity which is frequently encountered in several major types of stroke possibly even more frequently than the classical abruptly completed stroke. Stroke-in-evolution is in fact a mosaic or constellation of conditions including various causes (large infarcts, lacunes, distal fields infarcts, hemorrhages), various types of evolution and various pathophysiological mechanisms. The number of well-studied clinical cases in the literature is surprisingly small. Many of the proposed definitions are not adequate. Although it has been advised that the concept of of progressing stroke be discarded, this advice seems premature considering that it is a common and critical condition and one which has been in fact imperfectly and incompletely investigated. Instead, it would appear better to organize a prospective study with detailed clinical reports, serial CT, angiography, and when possible NMR PET or SPECT and detailed pathological examination of brain and extra-intracranial cerebral arteries. The magnitude of the task is such that a multicenter study would probably be required.
Influence of contralateral obstructions on Doppler-frequency spectral analysis of ipsilateral stenoses of the carotid arteries.
Authors: Fischer M , Alexander K
Published: June 2011

Contralateral obstructions have been suggested to be responsible for inaccuracy in Doppler sonographic diagnosis and estimation of severity of internal carotid artery stenoses. Therefore correlations of the systolic peak frequency of the internal carotid artery (Doppler-Frequency-Spectrum-Analysis) and severity of stenoses found by angiography have been compared in subgroups with (n = 36) and without (n = 48) additional contralateral obstructions. The linear regressions in both subgroups were found to be very similar (Y = 0.0098X - 12.4 and Y = 0.0099X - 14.0), the coefficients of correlation identical (r = 0.83). In 26 patients, the systolic peak frequency of the internal carotid artery did not demonstrate a significant change due to operation of the contralateral vascular lesion; thus indicating that contralateral obstructions do not influence CW-Doppler sonographic findings of an ipsilateral vessel wall lesion concerning diagnostic accuracy and non-invasive estimation of the severity of stenoses.
In vivo effects of alpha-adrenoceptor agonists and antagonists on pial veins of cats.
Authors: Ulrich K , Kuschinsky W
Published: June 2011

Cerebral blood volume and intracranial pressure may be modified by influences on cerebral veins. The known adrenergic innervation of cerebral veins and their sensitivity to norepinephrine raised the question, whether pial veins can be selectively influenced through adrenoceptors in vivo. Therefore, alpha 1 and alpha 2 adrenoceptor agonists and antagonists were locally injected into the perivascular space of pial veins using the microapplication technique. The alpha 1 and alpha 2 adrenoceptor antagonists, prazosin and yohimbine, had only minor effects on pial veins. Both antagonists blocked constrictions induced by norepinephrine (10(-5)M) in a concentration dependent manner (10(-7)-10(-4)M). The alpha 1 adrenoceptor agonist phenylephrine caused significant (10(-7)-10(-3)M) constriction of pial veins, with a maximum of 11.6% of initial diameter at 10(-3)M. Oxymetazoline, an alpha 2 receptor agonist, induced a significant constriction only at 10(-3)M (5.1%). Since both alpha 1 and alpha 2 adrenoceptor agonists are less potent constrictors of pial veins than norepinephrine in vivo, a preferential use of alpha 1 or alpha 2 adrenoceptor agonists cannot be recommended from these experiments, if a therapeutic reduction of intracranial pressure or blood volume is desired.
Amaurosis fugax as the presenting manifestation of dural arteriovenous malformation.
Authors: Bogousslavsky J , Vinuela F , Barnett H J , Drake C G
Published: June 2011

A 46-year-old woman under investigation for three episodes of amaurosis fugax in the left eye proved to have a left anterior-middle fossa dural arteriovenous malformation with pial venous drainage. The malformation received its main supply from the left middle meningeal artery, but its anterior part was fed by the recurrent meningeal branch of the left ophthalmic artery. Transient episodic lowering of retinal arterial pressure due to shunting of blood from the ophthalmic artery to the malformation is the most likely explanation for the occurrence of amaurosis fugax, indicating that this symptom occurs in some patients on a hemodynamic basis.
Injury of the peripheral cranial nerves during carotid endarterectomy.
Authors: Theodotou B , Mahaley M S
Published: June 2011

The incidence of local nerve injury among 192 consecutive carotid endarterectomies in 162 patients between 1977-1983 was determined from review of the medical records. Two facial nerve, 5 hypoglossal nerve, and 2 vagus nerve injuries were discovered for a total incidence of 4.7%. Only the 2 facial nerve injuries failed to improve over 2 years. Followup ranged from 1 to 60 months in this group of patients. Careful attention to details of tissue dissection at surgery should lower the incidence of nerve injury during carotid endarterectomy.
Bilateral occlusions in the cervical portion of the internal carotid arteries in a child.
Authors: Tagawa T , Mimaki T , Yabuuchi H , Iwata Y , Makino A
Published: June 2011

An 8-year-old boy with a history of recurrent tonsillitis and cervical lymphadenopathy developed acute hemiplegia. Cerebral angiography revealed bilateral occlusions of the cervical portion of the internal carotid arteries. Cerebral arterial occlusion in childhood has been attributed to many causes, e.g., trauma and infections of the neck. In the present case, though not clearly proved, inflammatory processes may have been related to the occlusion.
Prolonged disturbances of regional cerebral blood flow in transient ischemic attacks.
Authors: Hartmann A
Published: June 2011

Regional cerebral blood flow (rCBF) was measured over both hemispheres in 20 patients with unilateral transient ischemic attacks (TIA) of the territory of the internal carotid artery on the day of the TIA. rCBF was estimated with the nontraumatic Xenon 133-inhalation technique using the initial slope index. 13 patients experienced their first TIA, 7 had several attacks. In 14 patients the first rCBF-measurement was performed during the presentation of clinical symptoms. The 2nd rCBF-measurement was done on day 2, the last one on day 7. Scans of the 15 patients studied with CT were normal. On day 1 mean rCBF of the TIA-side was significantly lower than that of the contralateral hemispheres. 22% of all areas showed a significant reduction of flow compared to mean rCBF. Mean rCBF of both the TIA- and the contralateral side was significantly reduced compared to the bi-hemispheric mean rCBF of a control group with no history of TIA or completed strokes but at least 2 risk factors for cerebrovascular disease. Whereas mean rCBF did not change in the contralateral side it increased significantly (+6.9%) in the TIA-side from day 1 to day 2 but not from there to day 7. This is reflected by the increase of the total number of ROI with normal flow from day 1 to day 2. Considering the actual flow and the flow course of that tissue which was believed to be responsible for the clinical symptoms the following regional patterns were observed: normal rCBF in 6 patients; early return to normal concomitant to the clinical course (n = 4).(ABSTRACT TRUNCATED AT 250 WORDS)
Internal carotid artery dissection after childbirth.
Authors: Wiebers D O , Mokri B
Published: June 2011

A 44-year-old woman developed a left cerebral infarction secondary to internal carotid artery dissection 6 days after childbirth. A cesarean section had been carried out after 14 hours of strenuous unsuccessful labor. Although in the past some authors have implicated oral contraceptives as a cause for carotid dissection, carotid dissection associated with childbirth has not been previously described.
Spontaneous dissections of the renal arteries in a patient with previous spontaneous dissections of the internal carotid arteries.
Authors: Mokri B , Stanson A W , Houser O W
Published: June 2011

An otherwise healthy 35-year-old woman suffered spontaneous dissections of both internal carotid arteries. She made an excellent recovery but was left with occlusion of the left internal carotid artery and a residual subcranial dissecting aneurysm of the right artery--both were asymptomatic. Eight years later, spontaneous dissections of both renal arteries occurred. The exact nature of the underlying arterial disease is not clear. Although fibromuscular dysplasia is suspected, other undetermined arteriopathy cannot be excluded.
Comparison of external lung monitoring with end-tidal air detection using the 133xenon inhalation method.
Authors: Hazelrig J B , Halsey J H , Wilson E M , Wills E L
Published: June 2011

When the 133Xe inhalation method is employed for measuring regional cerebral blood flow, the arterial 133Xe concentration is usually approximated by the end-tidal air concentration. However, this approximation may be invalid in the presence of certain lung pathologies or when the breathing pattern is irregular. Jaggi and Obrist, using an intravenous injection of 133Xe, suggested that the counts detected by an external lung probe could provide an alternative estimate for arterial blood concentration once the noise produced by 133Xe in superficial tissues is removed from the signal. A mathematical model, based on hypotheses similar to theirs is presented here together with a new computational procedure for removing the noise. Results from normal rest studies on ten healthy young males indicate that the approximations for arterial blood concentration obtained from end-tidal air and from corrected lung counts are not equivalent when 133Xe is administered by inhalation. The concentration-time curves have different shapes, and these differences are reflected in blood flow values computed by head channel. However, there is no effect on comparisons between homologous regions of the left and right hemispheres.
Reproducibility of carotid artery Doppler frequency measurements.
Authors: Fischer M , Alexander K
Published: June 2011

Doppler sonography of 29 extracranial carotid arteries was performed twice within three days or less. Angiography revealed stenoses with from 10 to 95% diameter reduction in 25 internal carotid arteries whereas four vessels were found to be normal. The systolic peak frequency of the internal carotid artery read from the Doppler spectrum (n = 29) could be reproduced very well. This was shown by a linear regression nearest the line of identical values with a coefficient of correlation r = 0.97 (p less than 0.001). Other values derived from the spectral analysis of the Doppler shift signal were not so well reproduced including the peak frequency ratio (systolic peak frequency of the internal carotid artery/systolic peak of the common carotid artery) (n = 22; r = 0.81; p less than 0.001). The mean frequencies read from the zero-crossing detector recordings (n = 20) could not be reproduced as demonstrated by a linear regression far away from the line of identical measurements with a coefficient of correlation r = 0.43 (p less than 0.05).
Central neural control of blood pressure and cardiac arrhythmias during subarachnoid hemorrhage in rats.
Authors: Lacy P S , Earle A M
Published: June 2011

Sudden death may follow subarachnoid hemorrhage which indicates involvement of neural mechanisms connected with the cardiovascular system. Since various regions of the brain mediate blood pressure and heart rate changes, these parameters and heart rhythm could be affected due to a subarachnoid hemorrhage near the circle of Willis which surrounds the hypothalamus, the highest center for autonomic control. To investigate this in the control group, intracranial pressure, blood pressure, and electrocardiogram were measured before and after a simulated subarachnoid hemorrhage; blood pressure and electrocardiogram were measured following midcollicular lesions in the decerebrate group both before and after a subarachnoid hemorrhage. The results demonstrate that an increase in systemic arterial blood pressure and premature ventricular contractions (with respect to unlesioned group, p less than 0.04) are mediated by forebrain areas and require the integrity of neuroanatomical connections with structures that are caudal to the midbrain. Since bradycardia and other electrocardiographic abnormalities could still be produced after midcollicular lesioning it is suggested that they can be mediated via the brainstem only without involvement of more rostral areas and may occur due to increased intracranial pressure.
Hemorrhagic complications of long-term anticoagulant therapy for ischemic cerebral vascular disease.
Authors: Levine M , Hirsh J
Published: June 2011

The main complication of anticoagulant therapy is bleeding. Although the use of long-term oral anticoagulants in patients with transient cerebral ischemia and/or minor stroke is controversial, anticoagulants are still used in some instances. We have carried out a literature review of the risk of hemorrhage during long-term oral anticoagulant therapy in patients with cerebrovascular disease to determine the rate of bleeding and the clinical and laboratory risk factors which predispose patients to bleeding. The risk of bleeding was substantial with major bleeding episodes ranging from 2% to 22% per year and fatal bleeds from 2% to 9% per year. Only hypertension emerged as an identifiable risk factor and its presence increased the relative risk of bleeding to more than two fold. Major bleeding was almost always intracranial, possibly because of associated hypertension or because of cerebrovascular disease per se. We could not detect a relationship between bleeding and the intensity of anticoagulant therapy, although major bleeding occurred frequently even with only moderately intense anticoagulant therapy. The net gain or loss in efficacy rate of treating patients with minor stroke with long-term oral anticoagulant therapy was examined and it was concluded that in order for such treatment to be beneficial, a risk reduction of more than 50% in stroke rate, and a major bleeding rate of less than 2% per year are required. Since the risk reduction for stroke and death with anticoagulant therapy is unlikely to be 50% and the risk of major bleeding likely to be more than 2%, the present evidence does not support the use of anticoagulant therapy in minor stroke.
Effects of dopamine on cortical blood flow and somatosensory evoked potentials in the acute stages of cerebral ischemia.
Authors: Nakagawa Y , Kinomoto H , Abe H
Published: June 2011

Effects of intravenous infusion of dopamine on local cortical blood flow (CBF) and somatosensory evoked potentials (SEP) was evaluated using canine cerebral ischemia, which was produced by middle cerebral artery occlusion. CBF was monitored with a H2 clearance method and SEP. P1 to N1 peak to peak amplitude (V1) was recorded by stimulating the sciatic nerve on the contralateral side. CBF and SEP recovered at doses of 5 and 10 gamma, despite almost no increase of systemic arterial pressure. CBF and SEP were restored at doses of dopamine of 20 and 30 gamma, with an increase of mean systemic arterial pressure 5 to 15 mm Hg and similar results were obtained at doses of 25 gamma. Recovery of SEP was slight at extremely high doses of dopamine (65 gamma), despite a definite increase of mean systemic arterial pressure (MSAP) and CBF.
Angiotensin II decreases mortality rate in gerbils with unilateral carotid ligation.
Authors: Fernandez L A , Spencer D D , Kaczmar T
Published: June 2011

Evidence indicates that after vascular occlusion, infusion of angiotensin II restores blood supply to ischemic tissues by stimulating the development of collateral circulation through a mechanism independent of the mechanical effects of increased blood pressure. To test this effect in focal cerebral ischemia, angiotensin II was intravenously administered for four hours to gerbils immediately after unilateral carotid ligation. Three different pressor doses, 50, 250, and 500 ng/kg/min, were used, and mortality rate was evaluated at 1 and 2 days after vascular occlusion. Two additional groups similarly prepared were infused either with saline or with the pressor agent metaraminol. There was a significant inverse relationship between the infusion dose of angiotensin II and mortality: the greater the infusion dose of angiotensin II, the lower the mortality rate. Infusion of metaraminol, at the dose chosen to mimic the pressor effect of the highest angiotensin II dose, yielded a mortality rate which was statistically indistinguishable from that obtained with saline infusion. It is concluded that the mortality rate after unilateral carotid occlusion is significantly reduced by intravenous administration of angiotensin II through mechanisms unrelated to its hypertensive action. Evidence suggests that this may occur by the enhancement of the development of collateral circulation and therefore the reduction of the severity of brain ischemia.
Dependence of cerebral arterial contractions on intracellularly stored Ca++.
Authors: Sasaki T , Kassell N F , Zuccarello M
Published: June 2011

The purpose of the present study was to evaluate the dependence of the arterial contractions induced by different vasoactive agents upon intracellularly stored calcium in canine versus monkey cerebral arteries. The potency for inducing contractions in Ca++-free media was in the order of 9,11-epithio-11,12-metano-thromboxane A2 (STXA2) greater than prostaglandin F2 alpha (PGF2 alpha) much greater than serotonin greater than K+ in canine basilar arteries, and STXA2 greater than PGF2 alpha much greater than serotonin = K+ in monkey basilar arteries.
Changes in cerebral blood flow and recovery from acute stroke.
Authors: Burke A M , Younkin D , Gordon J , Goldberg H , Graham T , Kushner M , Obrist W , Jaggi J , Rosen M , Reivich M
Published: June 2011

We prospectively studied 14 patients with acute cerebral infarctions using serial 133Xenon inhalation cerebral determination (133Xe-rCBF), scored neurological examinations, and neuropsychological testing. All patients underwent the same battery of tests at 3 days, 1 week, 2 weeks, and 4 weeks after cerebral infarction to determine the prognostic value of early rCBF studies and the chronological relationship of changes in rCBF to clinical status. Baseline rCBF within 3 days of symptoms of acute stroke did not correlate with clinical neurological outcome (r = -0.17, p less than 0.30; r = -0.18, p less than 0.28, for the two indices of rCBF used). Among the 11 patients demonstrating neurological recovery, 7 improved at 1 week, significantly before increases in rCBF (p less than 0.05). We conclude that early baseline rCBF does not predict clinical outcome in patients with acute cerebral infarctions and that return of neurological function precedes rather than follows increases in rCBF.
Effect of topical nimodipine versus its ethanol-containing vehicle on cat pial arteries.
Authors: Auer L M , Mokry M
Published: June 2011

Nimodipine and its solvent containing ethanol were tested in a randomized in vivo study by local administration to the outer vessel wall surface of pial arteries and veins in 15 anesthetized cats. Reactions were studied through a cranial window. Diameter variations of 90 arterial and 78 venous vessel segments were continuously analyzed using a multichannel videoangiometer. The solvent alone caused minor though statistically significant (p less than 0.001) 7.6% dilatation, 8% in small and 7% in large arteries, which returned to their resting state after stopping treatment. 2.4 X 10(-5) M nimodipine plus solvent induced a 21% pial arterial dilatation (p less than 0.001), 26% in small and 17% in large arteries; dilatation induced by nimodipine plus solvent was significantly greater than dilatation by the solvent alone (p less than 0.001). After ceasing topical administration, arteries remained dilated by some 5%. Pial veins exhibited only minor reaction, i.e. a 6% (statistical n.s.) dilatation of large veins during nimodipine, and an 8% dilatation of small veins 20 minutes after stopping nimodipine. During solvent-administration rCBF, as estimated with the hydrogen clearance technique, remained unchanged. It is concluded that the dilatatory effect of the investigated compound on pial arteries is predominantly due to nimodipine.
Trends in mortality from cerebrovascular disease in Italy, 1955-78.
Authors: La Vecchia C , Decarli A
Published: June 2011

Trends in age-specific and age-standardized death certification rates from all cerebrovascular diseases and various diagnostic subcategories in Italy during the period 1955-78 have been analysed. In both sexes, a decrease in excess of 25% was evident in the overall age-standardized cerebrovascular disease mortality. However, rates were roughly stable in males up to age 50 and in females up to age 45, and slightly but consistently increasing in the younger age groups (under 40), mostly in females. The largest downward trends were for both sexes in the 55 to 74 age groups, and the declines were more marked in females, averaging 3% per year. Since death certification is most reliable in the younger age groups and it is difficult to imagine any modification of risk factors which should affect mortality in later middle age but not in younger age groups, there is no obvious and simple interpretation of this pattern of trends. A comparison with similar trends in ischemic heart disease and other causes of death suggests that the decline in overall cerebrovascular disease mortality might be partially or largely artefactual, though a between-sexes comparison indicates that at least part of the decrease registered in females may well be real. The extent of the decline, however, has been almost certainly more limited in Italy than in most other Western countries. Only in the younger age group (30-34) did rates show a larger increase in females, which might be related to increased prevalence of cigarette smoking, or the use of oral contraceptives.
Substrate-specific stimulation by glucagon of isolated murine brain mitochondrial oxidative phosphorylation.
Authors: D'Alecy L G , Myers C L , Brewer M , Rising C L , Shlafer M
Published: June 2011

Glucagon has been shown to increase further the enhanced tolerance for hypoxia of mice with elevated blood ketones and to stimulate ketone utilization by rat brain slices, suggesting that glucagon may affect brain metabolism. In addition to stimulating gluconeogenesis, glucagon alters the metabolism of mitochondria isolated from liver and heart. This study was designed to test whether glucagon can act directly and selectively on brain mitochondrial substrate oxidation. Mitochondria were isolated from normal murine brains using differential centrifugation through Ficoll gradients. Glucagon (3.6 microM) stimulated respiration in the presence of glutamate, and glutamate plus beta-hydroxybutyrate, but not in the presence of glutamate plus malate, succinate or beta-hydroxybutyrate alone. With glutamate as the substrate the hormone significantly increased State 3 oxygen consumption rates from control values of 91 mol O2/mol of cytochrome aa3/min to 117 mols O2/mol/aa2/min (p less than 0.0001), and also increased State 4 rates slightly but significantly. Glucagon did not change mitochondrial respiratory control ratios, but increased estimated rates of ATP synthesis from 434 (control) to 597 mols ADP consumed/mol aa3/min (p less than 0.0001). The data indicate that in vitro glucagon has a direct and substrate-specific stimulatory effect on isolated brain mitochondria. These substrate-specific effects were not altered when respiration was studied in the presence of postmitochondrial supernatant or exogenous 3',5'-cyclic AMP, indicating that glucagon, in addition to an in vivo action via activation of membrane-bound adenylate cyclase, can act, at least in vitro, directly and selectively on brain mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)
Presynaptic inhibitory action of adenosine on neuromuscular transmission in the canine cavernous carotid artery.
Authors: Fujiwara S , Kassell N F , Sasaki T , Yamashita M , Zuccarello M
Published: June 2011

We investigated the effect of adenosine on neurogenic contraction of the canine cavernous carotid artery, using an isometric tension recording device and transmural nerve stimulation. Adenosine, in concentrations under 10(-5)M, had no relaxing effect on the contractions produced by high [K]o solution or 10(-5)M norepinephrine. Transmural nerve stimulation (stimulus: 1 msec duration, 100V intensity) evoked a frequency-dependent contraction, which was abolished by 3 X 10(-7)M tetrodotoxin. Adenosine in concentrations of 10(-6)M and 10(-5)M, inhibited the neurogenic contraction at each frequency, more so in the low frequency range. This inhibitory effect of adenosine was significantly antagonized by 10(-5)M theophylline. Pretreatment with 2 X 10(-8)M dipyridamole had no effect on neurogenic contractions, but augmented the inhibitory effect of adenosine. 10(-5)M theophylline did not augment the neurogenic contractions. The findings that both dipyridamole and theophylline failed to affect the neurogenic contractions in the absence of adenosine suggests that the presynaptic autoinhibition mechanism of adenosine may not be involved in neuromuscular transmission in this tissue. These results suggest that there is a presynaptic adenosine receptor in the nerve terminal which inhibits the release of neurotransmitter in canine cavernous carotid artery. It is also probable that the vasodilating effect of adenosine in the cavernous carotid artery is mainly due to its inhibitory effect on neurotransmission rather than to a direct relaxing effect on smooth muscle.
Mechanism of in-hospital cerebral ischemia.
Authors: Kelley R E , Kovacs A G
Published: June 2011

Of 171 patients evaluated prospectively and consecutively for cerebral ischemia, 26 (15%) developed symptoms while hospitalized. Cerebral ischemia complicated operative procedures in 12 patients, unsuccessful cardioversion in one and coronary angiography in another. Twelve patients had apparent cerebral embolism and 14 patients had cerebral thrombosis as a mechanism of their symptoms. Hospitalized patients who suffered cerebral ischemia had one or more of the following: risk factors for stroke including cardiac source of embolus, previous stroke, diagnostic or therapeutic procedures for vascular disease, or chronic hypertension complicated by acute hypotension.
Effect of ischemia on hydroxylase cofactor (tetrahydrobiopterin) and monoamine neurotransmitters in rat brain.
Authors: Iijima S , Hara K , Suga H , Nakamura S , Kameyama M
Published: June 2011

Hydroxylase cofactor, monoamine neurotransmitters and their metabolites were measured in ischemic rat brain produced by four-vessel occlusion for 30 and 60 min periods. Slight reduction of hydroxylase cofactor activity was observed in the ischemic cortex after 60 min. Dopamine increased in the brainstem, and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, increased throughout the brain. Decrease in norepinephrine was observed in the whole brain. Decrease in serotonin and increase in 5-hydroxyindoleacetic acid, a metabolite of serotonin, was observed in the ischemic cerebral cortex. The present study has revealed that there appears to be no significant relationship between hydroxylase cofactor activity and monoamine levels in the ischemic brain. Thus, the hydroxylase cofactor does not play a main role in regulating monoamine synthesis in the acute phase of brain ischemia.
The effect of antiplatelet therapy on the incidence of carotid plaque hemorrhage.
Authors: Ernst R L , Ammar A D , Lin J J , Travers H
Published: June 2011

Hemorrhage into the carotid atheroma has recently been gaining attention with respect to the pathophysiology of cerebrovascular disease. Many patients are currently receiving platelet agents for various vascular diseases. Some researchers have postulated that antiplatelet therapy may be detrimental by possibly inducing intraplaque hemorrhage or by increasing preexisting hemorrhage. This retrospective study was undertaken to determine if the use of antiplatelet therapy increases the incidence of carotid plaque hemorrhage. Ninety-five consecutive carotid endarterectomies were performed and the atheromas examined microscopically for intraplaque hemorrhage. The atheromas were divided into two groups; those from patients receiving preoperative antiplatelet therapy and those who were not. Forty-five atheromas were removed from patients receiving preoperative antiplatelet therapy; 39 (87%) of these demonstrated intraplaque hemorrhage. Of the 50 atheromas which were removed from patients not receiving preoperative therapy, 45 (90%) showed intraplaque hemorrhage. We conclude that antiplatelet therapy does not increase the incidence of carotid plaque hemorrhage.
Magnetic resonance imaging in Wallenberg's lateral medullary syndrome.
Authors: Ross M A , Biller J , Adams H P , Dunn V
Published: June 2011

Four patients with a clinical diagnosis of Wallenberg's lateral medullary syndrome were studied with both Magnetic Resonance Imaging (MRI) and cranial Computed Tomography (CT). Using transverse images and both T1 and T2--weighted sequences, MRI demonstrated a medullary infarction not seen on CT in all four cases. MRI also demonstrated a coexisting cerebellar infarction in three cases which was unsuspected clinically and undetected by CT.