bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholesterol crystal embolization in rat brain: a model for atheroembolic cerebral infarction.
Authors: Steiner T J , Rail D L , Rose F C
Published: June 2011

Acute and delayed effects of embolizing cerebral surface vessels with cholesterol crystals were studied by direct observation in anesthetized rats and rabbits, using an open-skull technique, and by histological examination of brains at intervals of one day and one week following embolization. The number and size spectrum of crystals, which were infused into the ipsilateral internal carotid artery, were believed to approximate those released by a rupturing large atheromatous plaque in man, but the other lipid materials contained in such plaques were intentionally excluded. It was found that cholesterol crystals had only limited ability to impede blood flow in the 20--80 mu diameter arteries in view. They were also inert within the lumen, causing no vessel wall reaction even after a week; nor was any evidence seen of a thrombogenic effect. Local caliber changes in the containing artery were reproducibly seen, with dilatation of the arterial segment proximal to the embolus and narrowing of the segment in front. These changes appeared to represent an active response of the vessel wall, rather than a passive response to alterations in intraluminal pressure. The difficulty in subsequently locating cholesterol emboli histologically was confirmed. Possible therapeutic implications for atheroembolic cerebral infarction in man were discussed.
A re-examination of physostigmine-induced cerebral protection in the hypoxic mouse. A critical assessment of the model.
Authors: Artru A A , Michenfelder J D
Published: June 2011

Using the hypoxic (FiO2 = 0.05) mouse model as originally described, the survival time following pretreatment with physostigmine was examined. The maximum increase in survival time was 87% following a physostigmine dose of 0.4 mg/kg. This increase was considerably less than that previously reported for this drug in a hypoxic mouse study wherein the standard method for exposing mice to hypoxia was altered. We speculate that this alteration in methodology resulted in small variations in FiO2 sufficient to account for the differences between these studies.
Steal phenomenon at unclamping during carotid endarterectomy.
Authors: Kaufman H H , Ward R E , Reilly E L , Handel S F
Published: June 2011

A patient is reported who during vigorous back bleeding after unclamping of the internal carotid artery during endarterectomy had EEG slowing and a postoperative increase in neurological deficit. This phenomenon, an apparent steal, has not been reported and suggests that EEG monitoring is as vital at unclamping as it is after clamping. The patient also raises questions about the risk of early endarterectomy for those who have persistent deficits, even with unobstructed vessels.
Hyperbaric oxygenation as an adjunct therapy in strokes due to thrombosis. A review of 122 patients.
Authors: Neubauer R A , End E
Published: June 2011

Results are reported using hyperbaric oxygenation (HBO) in 122 patients with strokes due to thrombosis, both acute and completed. HBO is used as adjunctive treatment and three appears to be justification for a controlled study to delineate the treatment further. The authors believe it is essential to treat patients with stroke at 1.5 to 2 atmospheres absolute (ATA).
Deleterious effect of glucose pretreatment on recovery from diffuse cerebral ischemia in the cat. II. Regional metabolite levels.
Authors: Welsh F A , Ginsberg M D , Rieder W , Budd W W
Published: June 2011

Glucose was infused intravenously into cats prior to cerebral ischemia. Brain concentrations of glucose, measured in 7 regions, were elevated 2.5-fold compared to those of non-infused animals. Ischemia of 15 or 30 minutes duration caused a greater accumulation of lactic acid in the brain of glucose-infused animals. Post-ischemic restitution of cerebral ATP, phosphocreatine, and lactate during 90 minutes of recirculation was severely impaired in the brain of animals pretreated with glucose compared to untreated animals. Thus, excess lactic acidosis may be a major factor interfering with metabolic restitution following cerebral ischemia.
Cerebral arterial contractions induced by human and bovine thrombin.
Authors: White R P , Chapleau C E , Dugdale M , Robertson J T
Published: June 2011

Purified human and bovine thrombin produced comparable tonic contractions in isolated canine basilar arteries. The magnitude of the contractions was closely related to the number of thrombin Units studied rather than to the amount of protein added to the isolation bath. Thrombin had a much slower onset of action, but was more potent in generating sustained contractions than either serotonin or prostaglandin F2 alpha. Moreover, in contrast to serotonin and prostaglandin F2 alpha, the contractions caused by thrombin were not terminated by equivalent washing. The thrombin-induced contractions were significantly inhibited by prostacyclin, meclofenamic acid, phenoxybenzamine and glycerol. Prostacyclin was the most potent of these inhibitors. The results suggest that thrombin in a "free" form may cause vasoconstriction, in addition to platelet aggregation, in hemostasis and could contribute to the genesis of cerebral vasospasm associated with subarachnoid hemorrhage.
Analysis of cerebrovascular action of diazoxide in conscious goats.
Authors: Dieguez G , Gómez B , Lluch S
Published: June 2011

The effects of diazoxide on cerebral blood flow were evaluated in unanesthetized goats under control conditions and after selective blockade of adrenergic or cholinergic receptors in cerebral vessels. Injections of diazoxide (1-27 mg) into the internal maxillary artery produced dose-dependent increases in cerebral blood flow, an increase of 90% occurring with the highest dose. Administration of phentolamine, propranolol, or atropine into the internal maxillary artery did not modify the cerebrovascular response to diazoxide. In reserpine-treated animals the cerebral effects of diazoxide were also unchanged. Intravenous injections of diazoxide (150-400 mg) produced sustained hypotension and tachycardia whereas cerebral blood flow was maintained within normal values or increased slightly. The normal cerebral vasoconstriction obtained with injections of norepinephrine directly into the internal maxillary artery was unaffected during the diazoxide induced-hypotension. These findings show that diazoxide exerts a powerful vasodilatory effect on cerebral vessels through mechanisms other than blockade of alpha-adrenergic receptors or inhibition of adrenergic activity. The results also indicate that activation of beta-adrenergic or atropine-sensitive vascular receptors in the cerebral response to diazoxide is negligible.
Comparison of Doppler ultrasonography with arteriography of the carotid artery bifurcation.
Authors: Weaver R G , Howard G , McKinney W M , Ball M R , Jones A M , Toole J F
Published: June 2011

Continuous-wave (CW) Doppler ultrasound imaging for prediction of arteriogrphic abnormality at the carotid bifurcation was carried out in 195 arteries of 105 patients. The Doppler method had no predictive value when compared to angiographic findings in arteries classified as 0-50% stenosis by Doppler. In 50-75% stenosis by arteriography Doppler accuracy was 52%. With stenosis of 76-99% Doppler imaging correlated with 71% reliability. When an arteriogram was compared with Doppler imaging the latter gave a "false negative" reading in 56% and "false positive" readings in 19%. We conclude that Doppler ultrasound evaluation provides important information regarding the state of the carotid bifurcation, which supplements the bedside evaluation, but it does not substitute for arteriography.
Radionuclide angiography and Doppler sonography to detect patients with cerebrovascular disease. A correlation with radiographic angiography.
Authors: Buell U , Leschem D , Rath M , Rose M , Marguth F
Published: June 2011

Cerebral radionuclide angiography with 99mTc pertechnetate (RNA) and directional Doppler sonography (DS) were employed to study patients with cerebrovascular disease (CBVD). The 86 patients investigated were divided following radiographic angiography (RGA) into normals (n = 26) and into patients with intracranial (n = 22) and extracranial (n = 38) vascular lesions. Of the patients with angiographically demonstrated CBVD, RNA detected 90%, DS 53.3%. The combined evaluation had a sensitivity of 93.3%. If intracranial arterial disease was excluded, the sensitivity of the studies was 92.1% for RNA and 84.2% for DS and combined evaluation had a sensitivity of 97.4%. The diagnostic accuracy by combined evaluation was 93.8% for the extracranial arterial lesions if the clinical findings were also used in patients with normal RGA pattern. RNA and DS complement each other as RNA contributes to the detection of intracranial blood flow alterations indicating vascular changes in either the extra- or intra-cranial vessels and helps confirm and complete DS findings.
Response of cerebral circulation to topical histamine.
Authors: Martins A N , Doyle T F , Wright S J , Bass B G
Published: June 2011

To study the effect of histamine (HA) on brain blood flow and capillary permeability, bilateral parietal craniectomies were made in cats anesthetized with nitrous oxide and ketamine. The dura was removed and solutions of HA in mock cerebrospinal fluid (CSF) in varying concentrations ranging from 10(-5) M to 10(-1) M were irrigated continuously onto the exposed brain while local cerebral blood flow was determined polarographically by hydrogen clearance. Capillary permeability was assessed by determining HA's effect on the 125I-albumin space of the brain. Electrical activity was monitored by electrocorticography. HA consistently dilated pial blood vessels and produced within 15 min a dose-related local hyperemia that subsided 30--60 min after HA was removed. Hyperemia was blocked by cimetidine. HA had no appreciable effect on either the blood-brain barrier to albumin or the electrical activity of the cortex. HA is pharmacologically capable of participating directly in the acute hyperemic response of the brain's microcirculation to physiologic and pathologic stimuli but has little effect on cerebrovascular permeability to protein.
Cerebral blood flow and edema following carotid occlusion in the gerbil.
Authors: Crockard A , Iannotti F , Hunstock A T , Smith R D , Harris R J , Symon L
Published: June 2011

A technique for measuring focal cerebral blood flow (CBF) and brain specific gravity (SG) in gerbils is described; CO2 reactivity and autoregulation were tested. The mean CBF was 29.5 +/- 4.5 ml/100 gm/min and brain SG 1.0500 +/- 0.0004. Unilateral carotid occlusion resulted in a reduction of flow to 12.8 +/- 5.8 ml/100 gm/min in the ipsilateral hemisphere with little change in the contraleteral hemisphere; there was also a decrease in brain SG. One hour after occlusion, brain edema, as judged by decreased SG, developed at CBF less than 20 ml/100 gm/min and reached maximal levels at 7 +/- 2 ml/100 gm/min. The amount of edema appeared to be related chiefly to the residual post-occlusion flow. With bilateral occlusion, CBF was close to zero and there was no change in SG, indicating that in the "no flow" situation, there is no edema.
Brain events associated with mitral valve prolapse.
Authors: Hanson M R , Conomy J P , Hodgman J R
Published: June 2011

The clinical and laboratory features of 24 patients with proven mitral valve prolapse (MVP) and brain dysfunction are reported. The age range of affected patients was between 20 and 63 years (average of 43) and 70 percent were women. MVP was documented prior to the brain illness in only 4 patients. The majority of patients experienced bland cerebral infarction. Disorders also included transient ischemic attacks, cerebellar infarctions, parencymatous and subarachnoid hemorrhage, seizures and retinal artery occlusion. Significant risk factors for stroke other than MVP were lacking in the patient group. Cerebral angiograms occasionally showed distal occlusions of small arteries suggesting embolic brain lesions. Our study suggests that MVP is a risk factor for stroke. We recommend echocardiography in patients with cerebral ischemia who lack clear, recognized risk factors for stroke. We believe the basis for this brain disorder to be emboli from damaged mitral valve leaflets.
Cholinergic regulation of intracerebral noradrenergic pathway-induced hypothalamic vasodilatation.
Authors: Klugman K P , Mitchell G , Rosendorff C
Published: June 2011

Stimulation of the intracerebral noadrenergic pathway (INP) increases hypothalamic blood flow as measured in conscious rabbits using a 133xenon washout technique. This increase is abolished by the intra-hypothalamic injection of 0.65 micrograms of the muscarinic antagonist atropine and by 5 micrograms of the nicotinic antagonist mecamylamine. Further, 1 micrograms of the cholinomimetic methacholine produces a similar vasodilation. While methacholine enhances the vasodilatation on stimulation of the INP, destruction of the pathway abolishes the entire vasodilator response to methacloline. Removal of the superior cervical sympathetic ganglia does not abolish vasodilatation. A role for endogenous acetylcholine in the INP-induced vasodilatation is thus proposed. This vasodilatation appears to act via an increase in neuronal activity with a resultant lowering of local pH, as 60 micrograms barbiturate and intra-hypothalamic bicarbonate abolish the dilatation completely. The cholinergic vasodilatation reported here is probably an excitatory effect on the INP and is not likely to be due to an inhibition of sympathetic vasoconstrictor tone.
Local cerebral blood flow following transient cerebral ischemia. II. Effect of arterial PCO2 on reperfusion following global ischemia.
Authors: Miller C L , Alexander K , Lampard D G , Brown W A , Griffiths R
Published: June 2011

Following 5 minutes of global ischemia, local cerebral blood flow (LCBF) was shown to have an initial reactive hyperemia that was followed, within the first hour, by persistent hypoperfusion (Part I). Intracranial pressure (ICP) was never elevated during the period of poor reperfusion. These experiments attempted to reverse the state of subnormal LCBF by inducing hypercarbia or hyocarbia or maintaining normocarbia. Although hypocarbia did increase LCBF at several electrode sites, neither the intracerebral steal syndrome nor the "squeeze" syndrome are a dominant consequence of hypercarbia in this model of global ischemia. Hypercarbia was consistently more effective in elevating LCBFs and in recovery of the electrocorticogram. It appears that, in the absence of raised ICP, hypercarbia may be preferred to normal or low PACO2,. Even though hypercarbia was superior to normocarbia or hypocarbia, hypercarbia was not a completely satisfactory regimen for reversing the state of poor reperfusion.
H2 clearance measurement of blood flow: a review of technique and polarographic principles.
Authors: Young W
Published: June 2011

H2 clearance is a powerful method for monitoring blood flow. Simple and inexpensive to implement, the method allows multiple in situ determinations of blood flow from any tissue in which a small electrode can be implanted. There is, however, evidence to suggest that H2 clearance is neither as accurate nor as local a measure of blood flow as generally supposed. Both in theory and practice, it probably cannot accurately determine blood flow rates greater than 100 ml/100 gm/min or localize blood flow to tissue volumes of less than 5 ml. Moreover, its experimental application is complicated by many technical problems hitherto largely ignored by workers in the field. Some of these problems arise from the limitations of the steady state polarographic technique used to measure tissue H2 concentrations. Other problems stem from the failure to consider possible sources of error in H2 clearance monitoring; these induce interference with the H2 signal by spurious electrode and tissue currents, and contributions from tissue ascorbate and O2. Nevertheless, with the appropriate safeguards and qualifications, H2 clearance is a valid and important approach to measuring blood
Cervical bruits in hemodialysis patients.
Authors: Duncan G W , Kirshner H S , Stone W J
Published: June 2011

Twenty-five patients receiving chronic hemodialysis were studied with systematic cervical auscultation and periorbital Doppler tests to determine the incidence of cervical bruits and their significance. Eighteen (72%) of the patients had bruits. All of the bruits heard in this study were loudest in the supraclavicular fossa, and in no patient was a bruit heard along the carotid arteries without a louder bruit of similar characteristics more proximally. No patient with a bruit in the area of the carotid bifurcation had an abnormal ipsilateral periorbital Doppler examination, and none had symptoms of cerebral ischemia. There was no evidence in these patients that the bruits were related to occlusive arterial disease. It is concluded that most cervical bruits in patients receiving hemodialysis are the result of a hyperdynamic circulatory state associated with anemia and arteriovenous fistulae.
Ischemic edema in stroke. A parallel study with computed tomography and cerebrospinal fluid markers of disturbed brain cell metabolism.
Authors: Terent A , Ronquist G , Bergström K , Hällgren R , Aberg H
Published: June 2011

Thirteen patients with stroke and one with TIA had repeated examinations with computed tomography (CT) of the head, examination of the cerebrospinal fluid (CSF) for adenylate kinase, glutathione, lactate, and albumin and clinical evaluations during the first fortnight after onset. In 9 patients with cerebral infarction edema shown on the CT scans was maximal on days 2--5, after which it diminished. In 2 patients with intracerebral hemorrhage the edema appeared early as a zone of low-attenuation around the high-attenuation area. Most patients with large lesions deteriorated clinically during development of the edema. In 3 patients the CT scans were inconclusive, probably because the lesion was too small. Adenylate kinase activity was present in all CSF samples during the period 6 hours-5 days, while glutathione was occasionally present in the CSF in 12 of the 14 patients. These findings are believed to indicate cell swelling and a leak in the plasma membrane. Based on these observations, it is suggested that initial ischemic edema is intracellular in patients with cerebral infarction, and that adenylate kinase in CSF is a sensitive marker for this type of edema.
Clinical phenomena and their correlation to angiographic findings in cerebrovascular disease.
Authors: Thurman D J , Millikan C H
Published: June 2011

Seventy-one patients who had cerebral angiography because of clinical evidence of focal ischemic cerebrovascular disease were studied. Seventy-seven per cent of these patients had an arterial lesion in the distribution appropriate to the symptoms. However, the degree of dissemination of the atherosclerotic lesions, lesion morphology and severity of stenosis could not be predicted from the clinical manifestations. The presence of atherosclerotic cerebrovascular disease can usually be predicted by analysis of the symptoms and signs, but the nature and extent of the lesions can only be determined using cerebral angiography.
Total cerebral ischemia: application of a new model system to studies of cerebral microcirculation.
Authors: Jackson D L , Dole W P , McGloin J , Rosenblatt J I
Published: June 2011

Reduction in cerebral blood flow (CBF) following global ischemia has been implicated as a pathogenetic mechanism in progressive brain damage seen after restoration of effective cardiac action and cerebral perfusion pressure. There are serious limitations to many of the techniques for measuring regional cerebral blood flow, particularly during low flow states. In 15 dogs anesthetized with thiopental, 12 minutes of total cerebral ischemia (TCI) was produced using a double balloon occlusion technique. Total and regional cerebral blood flows were sequentially measured before and after balloon release by left ventricular injection of 15 mu microspheres labelled with 5 different radionuclides. Total CBF was reduced 53 +/- 5% (mean +/- SEM) from pre-ischemic values between 1 and 3 hours after "resuscitation" despite normal perfusion pressure and arterial blood gases. CBF remained slightly reduced (24 +/- 7%) at 6 hours post-ischemia. Thirty minutes after balloon release, grey matter flow was reduced 38 +/- 8% from control values while adjacent white matter flow was increased 21 +/- 10%. However, by 1 hour after ischemia, grey and white matter flows were both reduced (60 +/- 3%, 41 +/- 5% respectively). Similar differences in brain stem and cerebellar flow were also observed. The majority (71-86%) of the reduction in total CBF seen at one hour post-TCI is due to increased cerebrovascular resistance, with 14-29% of the decrease related to arteriovenous shunting.
Ultrasonic Doppler assessment of hemodynamics in gradual carotid ligation.
Authors: Moritake K , Handa H , Yonekawa Y , Takebe Y , Kishimoto S , Makimoto K
Published: June 2011

Hemodynamic changes were examined with an ultrasonic Doppler flowmeter and with a sound-spectrograph in 5 patients with internal carotid giant aneurysms or with recurrent laryngeal cancer undergoing gradual carotid occlusion. The ultrasonic Doppler technique was useful for preoperative assessment of intracranial cross-filling and as a practical guide for the graded reduction of blood flow in the carotid artery. The degree of flow increase in the contralateral carotid artery when the ipsilateral carotid artery was totally occluded was greater in postoperative gradual occlusion than in intraoperative rapid occlusion. In one patient with bilateral internal carotid artery giant aneurysms, whose left internal carotid artery had already been ligated at its origin, gradual occlusion of the right internal carotid artery was performed after the bilateral superficial temporal artery-middle cerebral artery (STA-MCA) anastomoses. Flow in the donor artery of the right STA-MCA anastomosis developed with increasing occlusion of the right internal carotid artery.
Giant fusiform aneurysm of the cerebral arteries.
Authors: Little J R , St Louis P , Weinstein M , Dohn D F
Published: June 2011

Giant fusiform aneurysm of the cerebral arteries was found in 11 patients during a 20-year period. The 7 males and 4 females ranged in age from 9 to 68 years (mean: 49 years). The supraclinoid segment of the internal carotid artery (ICA) and the M-1 segment of the middle cerebral artery (MCA) were the most frequently involved arteries. Multiple aneurysms were identified in 3 patients. Compression of adjacent intracranial structures was the usual cause of symptoms, and only 2 patients experienced subarachnoid hemorrhage. One patient presented with transient ischemic attacks. Computed tomography, with and without Hypaque infusion, clearly demonstrated the aneurysms in the 6 of 7 patients studied. Thrombus was invariably seen in the lumen of the aneurysm. Cerebral angiography in 11 patients displayed marked dilatation and elongation of the involved artery. The dilatation frequently extended into connecting arteries. Surgical treatment was carried out in 6 patients, including 2 with aneurysm entrapment and decompression, 2 with proximal ICA ligation, 1 with wrapping and 1 with wrapping and superficial temporal artery (STA) to MCA anastomosis. Death occurred in 2 patients not treated surgically.
Microcirculatory obstruction in focal cerebral ischemia: albumin and erythrocyte transit.
Authors: Little J R , Cook A , Cook S A , MacIntyre W J
Published: June 2011

The objectives were to study plasma and erythrocyte flow in an area of acute focal cerebral ischemia and define their relationship to developing microcirculatory obstruction as determined by morphological techniques. Eighteen adult cats, anesthetized with ketamine hydrochloride, had right middle cerebral artery (MCA) occlusion. Plasma flow was determined by measuring the transit of Iodine-131 (131I) albumin and erythrocyte flow was determined by measuring the transit of Technetium-99 (99Tc) labeled erythrocytes in the right Sylvian region. Transit studies were performed before and immediately after right MCA occlusion and at the end of the ischemic period, 1 hour, 3 hours, or 6 hours after occlusion. Intra-arterial perfusion with a buffered formaldehyde - colloidal carbon solution was carried out after completion of the isotope studies. Swelling of cerebral tissue and impaired carbon filling in the right MCA territory were seen initially after 3 hours occlusion and were more severe after 6 hours occlusion. Ischemic neuronal alterations, edema formation, and capillary luminal narrowing increased with longer periods of occlusion. 131I albumin transit time in the right Sylvian region was 8 +/- 2 seconds before occlusion and 10 +/- 2 seconds immediately after occlusion. 99Tc erythrocyte transit time was 10 +/- 2 seconds before occlusion and 12 +/- 3 seconds immediately after occlusion. 99Tc erythrocyte transit time was 10 +/- 2 seconds before occlusion and 12 +/- 3 seconds immediately after occlusion. Transit times increased progressively with longer periods of occlusion in cats developing cortical ischemic changes. No evidence of complete microcirculatory obstruction to albumin and erythrocyte transit was seen in cats with 6 hours of occlusion despite the impaired filling of the cortical microcirculation with carbon. There were no findings to substantiate the hypothesis that plasmapheresis develops during the early phases of cerebral infarction.
Influence of superficial temporal artery to middle cerebral artery bypass on cerebral blood flow in dogs with middle cerebral artery occlusion.
Authors: Hitchon P W , Kassell N F , Gross C E , Adams H P , Hill T R
Published: June 2011

Eight dogs had a superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis, followed immediately by ligation of the ipsilateral middle cerebral artery. Subsequently, utilizing the radioactive microsphere technique, regional cerebral blood flow determinations were made both before and after ligation of the superficial temporal artery. A significant reduction in blood flow of 20-35% was noted in both cerebral hemispheres, caudate and thalamic nuclei, brain stem and cerebellum following occlusion of the bypass. It is our impression that this generalized reduction in flow is due to a redistribution of blood from normal areas previously supplied by the bypass. This implies that the newly created extracranial to intracranial arterial anastomosis reduces the shunting of blood from zones of higher to zones of lower flow through the circle of Willis and leptomeningeal collaterals. It also suggests a mechanism for the development in neurological function referable to areas of the brain remote from the bypass which is detected in some patients after STA-MCA anastomosis.
Regional arm-brain mean transit time in the diagnostic evaluation of patients with cerebral vascular disease.
Authors: Bartolini A
Published: June 2011

By analyzing time-activity curves over selected brain regions, following intravenous administration of non-diffusible radionuclide, it is possible to assess regional arm-brain mean transit time (rABmtT). By evaluating this parameter in normal subjects a relatively small range of differences between asymmetrical regions can be found (0.30 +/- 0.14 sec, mean +/- SD). An increase of this difference above statistical limits was found in 82% of patients with acute complete stroke, in 56% of patients with chronic complete stroke in 21% of patients with transient ischemic attacks.
Long-term outcome in cerebrovascular disease in relation to findings at aortocervical angiography. A 12-year follow up.
Authors: Asplund K , Liliequist B , Fodstad H , Wester P O
Published: June 2011

The natural history of cerebrovascular disease (CBVD) was evaluated in 169 non-treated patients followed for at least 12 years after aortocervical angiography. The outcome was related to type and location of atherosclerotic changes in the neck vessels. At the time of angiography, 108 patients had completed strokes, 20 had transient ischemic attacks (TIAs), and 41 had angiography for reasons other than acute CBVD. In patients with stroke, non-stenotic lesions as well as stenoses/occlusions were associated with a better long-term survival when they affected the vertebral territory than when the carotid arteries were involved. Patients with normal angiograms had no better prognosis than those with non-stenotic atherosclerosis. Only 2 of 12 deaths in patients with lesions in the vertebral artery were caused by cerebrovascular accidents. In all other groups (normal, carotid lesions only, changes in both carotid and vertebral arteries) the majority of deaths were attributed to CBVD. Rates of recurrent stroke were relatively low in patients with changes in the vertebral arteries and in subjects with non-stenotic lesions in one carotid artery. Intermediate rates were observed when the angiograms were normal, high rates when compound lesions had been demonstrated at angiography. Results show that in patients with stroke the location of atherosclerotic changes to different vessel territories appears to predict the clinical course better than the extent of the lesion(s). No specific angiographic finding was associated with a high initial and a low rate of stroke recurrencies. Therefore, drug therapy to prevent recurrent stroke must probably be life-long in all patients with CBVD not treated by surgery.
A simple, non-dimensional, normalized common carotid Doppler velocity wave-form index that identifies patients with carotid stenosis.
Authors: Archie J P
Published: June 2011

A non-invasive Doppler velocity index that is specific for carotid artery stenosis is presented. The index is both non-dimensional (maximum/minimum velocity to remove within artery Doppler signal variability) and normalized (larger over smaller carotid maximum/minimum ratio to minimize between patient variability). Of 260 normal patients 94% had a maximum/minimum index between 1.00 and 1.25 and 97.5% had an index between 1.00 and 1.30. In 136 patients undergoing selective carotid arteriography the overall accuracy of the maximum/minimum index in predicting carotid stenosis was 85-87%. When 1.30 is taken as the maximum normal index value the test is 96.5% specific and 76% sensitive. The receiver operating characteristic curve indicates that patients with a maximum/minimum index greater than 1.4 have a 99% probability of significant carotid stenosis.
Abnormal catecholamine urinary excretion after emotional stimulus in patients with cerebral hemorrhage.
Authors: Stoica E , Enulescu O
Published: June 2011

The epinephrine (E) and norepinephrine (NE) urinary excretion before and after a mild "emotional stimulus" (ES) was determined in 22 patients with cerebral infarction and 30 patients with cerebral hemorrhage, as well as in 18 normotensive and 18 hypertensive controls. In patients with cerebral infarction, the majority normotensive, the "emotional stimulus" induced a significant increase in NE excretion, but non-significant alterations in E excretion. Similar changes were noted in normotensive controls. In patients with cerebral hemorrhage, almost all hypertensive, and in hypertensive controls, ES brought about a consistent rise in E excretion without influencing significantly the NE excretion. The presence of a constant increase in E excretion after a mild emotion not only in patients with cerebral hemorrhage but also in subjects with uncomplicated essential hypertension, suggests that the E release found in patients with cerebral hemorrhage is related to the hypertensive state pre-existing the stroke rather than to hemorrhagic stroke itself. The pattern of catecholamine discharge in hypertensive patients might play a part in the occurrence of cerebral hemorrhagic accidents. The epinephrine discharges induce sudden increases in systolic blood pressure which could lead to the rupture of cerebral vessels with hyalinotic or atherosclerotic alterations.
Postnatal undernutrition accelerates incidence of stroke in stroke-prone spontaneously hypertensive rats.
Authors: Matsuo T , Nagaoka A
Published: June 2011

The effect of infantile nutritional levels on the development of hypertension and incidence of stroke was investigated in stroke-prone spontaneously hypertensive rats (SHRSP). Caloric intake was varied during the suckling period by manipulating litter size immediately after birth; however, all animals had free access to food after weaning. Animals reared in large litters of 15 (LL group) weighed significantly less than those in small litters of 5 (SL group) at every age. In the LL group, systolic blood pressure (mean +/- SD) increased age-dependently to reach 237 +/- 16 mm Hg at 14 weeks of age, and 14 of 15 rats developed stroke from 14 to 19 weeks of age. On the other hand, in the SL group, the blood pressure at 14 weeks of age was 213 +/- 6 mm Hg, which was significantly lower than that in LL group, and stroke occurred only in 3 of 10 rats kept up to 22 weeks. When the drinking water was replaced with a 1% salt solution, the onset of stroke markedly accelerated in both groups; more than 90% of rats developed stroke within 18 days after the salt-loading. However, the time required for the onset of stroke signs was significantly shorter in the LL group (10.5 +/- 1.5 days) than in the SL group (15.4 +/- 1.7 days). Furthermore, the blood pressure increment for the first week after the salt-loading was significantly greater in the LL group (29.5 +/- 9.5 mm Hg) than in the SL group (14.2 +/- 3.0 mm Hg). These findings indicate that infantile undernutrition may accelerate the development of hypertension and incidence of stroke in SHRSP.
Cortical blood flow: thermal diffusion vs isotope clearance.
Authors: Carter L P , Erspamer R , Bro W J
Published: June 2011

A thermal diffusion flow probe incorporating a Peltier stack has been found to give a quantitative dynamic assessment of cortical blood flow in both the laboratory and clinical settings. Further calibration characteristics of the probe were evaluated by correlation with the fast component of Xe133 clearance in cats. The correlation has some linear characteristics but is better defined by the equation: CBFp = phi(1/delta V - 1/delta Vo) Where CBFp is flow in ml/100 g/min, delta V is the voltage difference of the thermocouples, and delta Vo is the voltage difference of the thermocouples with no flow, which was 342.8 +/- 12.9 microv. Phi describes the characteristics of the probe and was determined to be 52,431.2 +/- 4796.3. The average deviation of the calculated curve from the experimental data points was +/- 6.3. The calculated phi differed markedly from the mean when Xe133 fast component flows were less than 35 ml/100 g/min. This is evidence that CBF as measured by Xe133 clearance analyzed by the bicompartmental technique loses accuracy at lower flows. The thermal diffusion flow probe is a good device for evaluation of flow in acute ischemia models since it can delineate abrupt flow variations. Theoretically the flow probe can accurately measure flow at ischemic levels.
Thalamic hemorrhage. A study of 23 patients with diagnosis by computed tomography.
Authors: Barraquer-Bordas L , Illa I , Escartin A , Ruscalleda J , Marti-Vilalta J L
Published: June 2011

A series of 23 patients with thalamic hemorrhage with computed tomography confirmation is reported. Nine of these died, all had hematomas larger than 3.3 cm. The value of the syndrome of downward and convergent ocular deviation is stressed, and its possible mechanisms are analyzed. The characteristics and mechanisms of the pupillary abnormalities are reported, as well as the speech abnormalities observed in patients with lesions of the dominant hemisphere. Prognostic conclusions are drawn.
Protective effect of Fluosol-DA in acute cerebral ischemia.
Authors: Peerless S J , Ishikawa R , Hunter I G , Peerless M J
Published: June 2011

Fluosol-DA (Perfluorochemical Blood Substitutes) are small particle fluorocarbons suspended in an emulsion and have a high propensity for carrying oxygen and carbon dioxide. Fluosol-DA was investigated for the modification of acute focal cerebral ischemia and compared to mannitol. A total of 36 adult cats were divided into 3 groups and had transorbital microtourniquet ligation of the middle cerebral artery (MCA). Control animals were given intravenous isotonic saline. Animals in the experimental groups were treated with either intravenous Fluosol-DA or mannitol. All animals were nursed in an oxygen chamber and 4 cats from each group were sacrificed at 1, 3 and 6 hours after MCA occlusion. The results of macroscopic and histological examination of the brain suggested Fluosol-DA had a definite protective effect on acute focal cerebral ischemia which was in keeping with the observed neurological outcome. It is suggested that Fluosol-DA may support flow in the microcirculation and that the small particles of Fluosol-DA may be able to reach the area of ischemia via collaterals by decreasing blood viscosity, preventing narrowing of the arteriolar and capillary lumen and increasing the cerebral blood flow.
Xenon and iodine enhanced cerebral CT: A closer look.
Authors: Gur D , Yonas H , Wolfson S K , Herbert D , Kennedy W H , Drayer B P , Shabason L
Published: June 2011

Xenon and iodine enhanced dynamic computerized tomography (CT) have been used experimentally to obtain both qualitative and quantitative information on local cerebral blood flow in both normal and infarcted tissue. Direct comparisons between Xenon enhancement, iodine enhancement and pathological findings demonstrate significant differences between results derived from each of the 2 in vivo techniques. While iodine enhanced dynamic CT yields valuable information concerning the patency and density of vasculature, xenon enhanced studies can provide highly focal information on cerebral tissue perfusion.
Treatment program and comparison between anticoagulants and platelet aggregation inhibitors after transient ischemic attack.
Authors: Burén A , Ygge J
Published: June 2011

Transient cerebral ischemic attacks (TIA) are an important warning symptom of threatening stroke from cerebral infarction (CI). A local treatment program aimed at identifying as many individuals with TIA as possible and treating them in a uniform manner is desirable. Platelet aggregation inhibitors with a combination of acetylsalicylic acid and dipyridamole (ASA + DP) has been compared with anticoagulants (AC). The average length of treatment was 24 months and all patients received the treatment for at least 6 months. Sixty patients received AC and 65 ASA + DP. Four patients in the ASA + DP group (6 percent) and 2 in the AC group (3.3 percent) sustained cerebral infarction. These figures are essentially lower than the expected incidence of 15--20 percent.
Cerebral extraction of N-13 ammonia: its dependence on cerebral blood flow and capillary permeability -- surface area product.
Authors: Phelps M E , Huang S C , Hoffman E J , Selin C , Kuhl D E
Published: June 2011

13N-labeled ammonia was used to investigate 1) the cerebral extraction and clearance of ammonia, 2) the mechanism by which capillaries accommodate changes in cerebral blood flow (CBF) and 3) its use for the measurement of CBF. The unidirectional extraction of 13NH3 in rhesus monkeys was measured during PaCO2 induced changes in CBF and dog studies were performed using in vitro tissue counting techniques to examine 13NH3 extraction in gray and white matter, mixed tissue and cerebellum during variations in CBF produced by combinations of embolization, local brain compression, and changes in PaCO2. The single pass extraction fraction of 13NH3 varied from about 70 to 20% over a CBF range of 12 to 140 cc/min/100 g. Capillary permeability-surface area product (PS) estimates with a Renkin/Crone model show PS increasing with CBF. The magnitude and rate of increase in PS with CBF was highest in gray matter greater than mixed tissue greater than white matter. Tissue extraction of 13NH3 vs CBF relationship was best described by a unidirectional transport model in which CBF increases by both recruitment of capillaries and by increases of blood velocity in open capillaries. This saturable-recruitment model provides a possible explanation for the mechanism of flow changes at the capillary level. The net 13NH3 extraction subsequent to an i.v. injection increases non-linearly with CBF. Doubling or halving basal CBF produced from 35 to 50% changes in the 13N tissue concentrations with further increases in CBF associated with progressively smaller changes in 13N concentrations.
Influence of timing of admission after aneurysmal subarachnoid hemorrhage on overall outcome. Report of the cooperative aneurysm study.
Authors: Kassell N F , Adams H P , Torner J C , Sahs A L
Published: June 2011

The overall management results after aneurysmal rupture were studied in 158 patients admitted to the hospital on day 0--3 and 175 patients admitted on day 4--7 following subarachnoid hemorrhage. In this series surgery was planned no sooner than 12 days following the ictus. Despite effective medical and surgical therapy overall results were disappointing: 3 months following the initial hemorrhage only 43% of patients in the 0--3 day group and 53% of patients in the 4--7 day group were capable of independent functional living. Patients admitted on days 4--7 also had a lower mortality rate, re-bled less frequently, and had lower postoperative mortality and morbidity than those admitted on days 0--3. For reasons not well defined, time of admission following aneurysmal SAH has an important influence on outcome. Accordingly, in evaluating outcome for patients with ruptured aneurysms treated with different therapeutic modalities, time of admission must be carefully controlled.
Physiological and morphometric analysis of the microcirculation of the cerebral cortex under acute vasospasm.
Authors: Wiernsperger N , Schulz U , Gygax P
Published: June 2011

Tissue PO2 measurements with microelectrodes and morphometric analysis of capillaries were combined to investigate microcirculatory changes in cat brains subjected to vasospasm (superfusion of platelet-poor plasma). It can be shown that vasospasm leads to marked tissue hypoxia as illustrated by a drastic shift in the PO2 distribution within the cortical tissue. Morphological measurements of various capillary parameters demonstrated a marked constriction in precapillary segments as well as in capillaries themselves. This decrease in perfusion of the capillary bed could not be compensated for by increasing the systemic arterial blood pressure. Our results demonstrate that, even with a platelet-poor fraction, marked changes occur on a microcirculatory level in the cerebral cortex with vasospasm, which may not be detected by macroscopic techniques.
Transient ischemic attacks and external carotid artery. A retrospective study of 23 patients with an occlusion of the internal carotid artery.
Authors: Bogousslavsky J , Regli F , Hungerbühler J P , Chrzanowski R
Published: June 2011

Twenty-three patients with occlusion of an internal carotid artery have been followed 5 to 50 months after angiography. None had a later permanent stroke. Eight had delayed TIAs in the occluded internal carotid area, never in another area. In these TIAs the role of the homolateral external carotid artery is emphasized, because in the 8 cases this artery was the main collateral to the occluded internal carotid, and angiography had shown atheromatous stenosis of homolateral external/common carotid arteries or an irregular stump at the site of the occlusion. Hemodynamic and embolic mechanisms are discussed, especially the latter, because of the absence of severe stenosis and evidence of emboligenic plaques.
Chronic vascular changes in the walls of experimental berry aneurysms of the aortic bifurcation in rabbits.
Authors: Stehbens W E
Published: June 2011

Experimental berry aneurysms were fashioned from an autogenous venous transplant by microvascular surgery at the aortic bifurcation of rabbits maintained on a stock diet. Structural changes in the aneurysms and in the host aorta were studied for periods up to 3 years 9 months postoperatively. Phlebosclerosis developed in the aneurysms and progressed to severe fibrosis, calcification, ossification, mural thrombosis and lipid deposition resembling human atherosclerosis, with eventual loss of the media. The host aorta exhibited pronounced intimal thickening at the bifurcation. The experiments demonstrated the importance of hemodynamic stress in the accelerated production of the degenerative changes in the walls of berry aneurysms.
Computed tomographic findings of good prognosis for hemiplegia in hypertensive putaminal hemorrhage.
Authors: Mizukami M , Nishijima M , Kin H
Published: June 2011

Computed tomography (CT) findings were analyzed in 17 patients with hypertensive putaminal hemorrhage accompanied by hemiplegia which had subsided almost completely by conservative therapy within one month after the onset. In such patients a high density area was not seen at the level of the lateral ventricles on CT scan. To study the reason for this, the relationship between the extent of a hematoma and the level at which the pyramidal tract was destroyed was investigated. From consideration of the process of destruction of the pyramidal tract by a hematoma, it seemed that CT findings at the level of the bodies of the lateral ventricles, rather than at the level of the posterior limb of the internal capsule, were of value in evaluating the prognosis of hemiplegia in putaminal hemorrhage.
Post-ischemic hypermetabolism in cat brain.
Authors: Nemoto E M , Hossmann K A , Cooper H K
Published: June 2011

Delayed postischemic brain hypoperfusion and hypermetabolism are likely detrimental factors to neurologic recovery after transient global brain ischemia and may be mediated by catecholamines acting via adrenergic receptors. We evaluated the effects of alpha and beta receptor blockade on cerebral blood flow (CBF) and metabolism after 16 min transient global brain ischemia. Ischemia was induced by arterial hypotension and a high pressure neck tourniquet in 13 anesthetized cats. Six cats were untreated, 4 received propranolol 1 mg/kg, IV and 3 a combination of propranolol and phentolamine, one mg/kg injected one min before recirculation. Total CBF was measured by continuous monitoring of cerebral venous 133Xe clearance after bolus intra-arterial injection. Arterial and cerebral venous oxygen, glucose and lactate were measured. Cerebral cortex glucose and lactate were measured 3 hours post-ischemia after in situ freezing with liquid N2. The cerebral cortex of 3 cats anesthetized, but not subjected to ischemia, was similarly frozen and analyzed for glucose and lactate. Total CBF was relatively constant for up to 3 h post-ischemia in all groups, but significant changes in fast and slow-flow rates and compartment sizes were observed. In untreated cats, the normal 60/40 percent relative weight of the fast and slow-flow compartments was reversed to 30/70 percent by 1 hr post-ischemia. Propranolol attenuated the size of the fast-flow compartment in the first 30 min post-ischemia which was partially restored by phentolamine. Brain oxygen consumption increased 2 to 3-fold by 1 h post-ischemia in all groups. Propranolol compromised CBF and impaired glucose and lactate oxidation which was partly reversed by phentolamine. We concluded that within the first 30 min post-ischemia, beta, and to a lesser extent, alpha receptors predominate in the modulation of cerebrovascular tone. By 1 h post-ischemia, however, adrenergic modulation of cerebrovascular tone is lost. Delayed post-ischemic hypermetabolism unlike stress-induced, but like hypoxia-induced hypermetabolism is only partially affected by beta blockade. Propranolol apparently compromises brain oxygen consumption secondary to a reduction in brain O2 supply while phentolamine improves perfusion and oxygen consumption.