bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevention of recurrent stroke.
Authors: Leonberg S C , Elliott F A
Published: June 2011

Victims of atherothrombotic infarction of the brain, the most common variety of stroke, frequently have recurrent strokes. Risk factors believed to accelerate such events include hypertension, diabetes mellitus, hyperlipidemia, atherosclerotic disease (of heart, aortocervical and intracranial vessels), erythrocythemia, stress, tobacco smoking, hyperuricemia, and perhaps obesity. Most prior studies indicate average anticipated 5 year mortality of 35 to 65 percent and stroke recurrence rate of 20 to 40 percent. A consistent effort to control risk factors in 88 survivors of a first cerebral infarction yielded 17 percent mortality and 16 percent stroke recurrence rates during the 5 years following first stroke. This sustained and systematic approach to risk factor management seemed beneficial to these stroke victims.
Clinical-angiographic correlation of ophthalmodynamometry in patients with suspected carotid artery disease: a prospective study.
Authors: Sanborn G E , Miller N R , McGuire M , Kumar A J
Published: June 2011

A prospective, clinical study was performed on patients with suspected carotid artery disease to compare the accuracy of compression and suction ophthalmodynamometry with carotid artery stenosis as determined by arteriography. Results were analyzed with respect to current criteria for classification and determination of "significant" carotid artery disease. Although our results suggest that the best correlation for both procedures with arteriography is a ratio of the corrected intraocular pressure to the systolic brachial blood pressure, these results were not statistically improved over those obtained using uncorrected systolic or diastolic values. Both suction and compression ophthalmodynamometry are equally accurate with levels approaching 80 percent; however, neither test is sensitive enough to be used alone as a screening technique. Arteriography remains the best procedure for the determination of carotid artery disease.
Sensitivity of computer assisted radionuclide angiography in transient ischemic attack and prolonged reversible ischemic neurological deficit. Comparison with findings in radiographic angiography and transmission computerized axial tomography.
Authors: Buell U , Scheid K F , Lanksch W , Kleinhans E , Ulbert V , Reger U , Rath M , Moser E A
Published: June 2011

Computer assisted radionuclide angiography (CARNA) with 99mTc-DTPA was employed to study 143 patients with transient ischemic attacks (TIA) and 79 patients with prolonged reversible ischemic neurologic deficit (PRIND). The results of CARNA were compared with findings from radiographic angiography (RGA) in 173 patients and with findings in transmission computerized axial tomography (T-CAT) in 154 patients. In patients with TIA, CARNA showed a hemispherical perfusion deficit in 74.8%, and with PRIND 87.3%. This deficit, determined as the relative difference between the involved and the non-involved hemisphere, was significantly (p less than 0.0025) greater in PRIND (minus 23%) than in TIA (minus 17%). Sensitivity of CARNA was independent of the interval from ictus to examination for more than 4 months. RGA in TIA revealed true positives in 82.0%, in PRIND it was 89.5%. T-CAT was positive in TIA in only 16.8% but in PRIND it was 64.4%. Combined sensitivities in TIA (92.4%) and in PRIND (94.0%) were highest with the combination of CARNA and RGA. However, in PRIND the combination of non-invasive methods (CARNA and T-CAT) revealed 93.2% positive findings. Combinations of these evaluation methods may be used to detect cerebrovascular disease in patients with such dysfunction.
Permeability of intracranial extracerebral vessels in stroke-prone SHR.
Authors: Tagami M , Kubota A , Sunaga T , Fujino H , Maezawa H , Kihara M , Nara Y , Yamori Y
Published: June 2011

Permeability of intracranial extracerebral arteries of stroke-prone spontaneously hypertensive rats (SHRSP) was studied using labeling techniques (ferritin and horseradish peroxidase), at the cellular level. In the arterial endothelial cells, the tracer molecules were slowly but constantly transported by the plasmalemmal vesicles to the subendothelial space. This endothelial transportation of the tracers into these cerebral arteries did not seem to be significantly influenced by aging, increased blood pressure, hyperlipidemia or the existence of cerebral bleeding and infarction. Around the adventitia, there were a great number of periadventitial capillaries, especially near bifurcations. In the periadventitial capillaries, the tracer molecules were readily trapped by endothelial cells and were quickly transported to pericapillary spaces. The tracer molecules were then detected in the phagocytes adjacent to the deeper layers of the media, and further in the medial smooth muscle cells. The possibility that large amounts of plasma components are supplied to the media from periadventitial capillaries in the intracranial extracerebral arteries has to be considered in the pathogenic mechanisms of cerebrovascular lesions.
Pure motor hemiplegia: CT study of 30 cases.
Authors: Rascol A , Clanet M , Manelfe C , Guiraud B , Bonafe A
Published: June 2011

Pure motor hemiplegia (PMH) is a well defined syndrome usually caused by ischemic lesions of lacunar type located either in the internal capsule or in the pons. Angiography and isotope scanning are usually normal. CT scan reveals small deep infarcts and appears to be the most reliable investigative method. The CT scan findings are described of thirty patients with PMH of rapid onset (less than 36 hours). In 29 of the 30 cases a lesion was found which could explain the PMH. Small hemorrhages (2 cm in diameter) in the posterior limb of the internal capsule were noted in two cases. Ischemic lesions were found in 27 patients, 22 patients had a single lesion (20 capsular and 2 pontine), while 5 patients had 2 lesions (2 bi-capsular, 3 capsular and pontine). Three varieties of ischemic capsular lesions were observed. We found in 15 cases a capsulo-putamine-caudate infarct (type I); in 8 cases a capsulo-pallidal infarct (type II); and in 2 cases an anterior capsulo-caudate infarct (type III). Type I corresponded to the area of the lateral lenticulostriate branches of the middle cerebral artery. Type II involved the territory of the perforating branches of the anterior choroidal artery. We suggest that type III involves the territory of the internal lenticulostriate branches of the anterior cerebral artery. Lacunes are generally linked to arterial systemic hypertension. However, only 16 of 30 patients in this series were chronically hypertensive.
Assessment of inter-observer differences in the Italian multicenter study on reversible cerebral ischemia.
Authors: Tomasello F , Mariani F , Fieschi C , Argentino C , Bono G , De Zanche L , Inzitari D , Martini A , Perrone P , Sangiovanni G
Published: June 2011

A standardized protocol was used for duplicate examination by two neurologists of the clinical history and neurological signs in 55 patients with reversible cerebral ischemia. One trained examiner from each of eight clinical centres involved in the Italian Cooperative Study on reversible cerebral ischemia participated in this research. Duplicate examination were compared in order to evaluate the percentage of agreement achieved in the responses. Several discrepancies relating to either historical data or neurological signs were detected. Possible causes of this disagreement are discussed. The inter-observer differences appear to be an important problem to be faced in cooperative studies on reversible ischemic attacks. The purpose of the study was to estimate these differences in the attempt to increase the degree of agreement by repeated training sessions and discussion between the different examiners. These efforts are needed to improve the quality of clinical investigations on reversible cerebral ischemia and to increase the validity of their results.
Dimethyl sulfoxide (DMSO) and glycerol, hydroxyl radical scavengers, impair platelet aggregation within and eliminate the accompanying vasodilation of, injured mouse pial arterioles.
Authors: Rosenblum W I , El-Sabban F
Published: June 2011

The hydroxyl radical scavengers dimethyl sulfoxide (DMSO) and glycerol were effective inhibitors of platelet aggregation in an in vivo mouse model of pial arteriolar injury. Aggregability was expressed in terms of the time required for a noxious stimulus (light + dye) to initiate aggregation. These drugs, given 1 hour before the injury, also eliminated the dilation which accompanied the damage. The same drugs failed to influence the constriction which accompanied an identical injury to mouse mesenteric arterioles, but again impaired platelet aggregation in the damaged mesenteric vessel. The data support the concept recently introduced by others, that, in the brain, hydroxyl radicals may mediate vascular damage and/or dilation accompanying the damage. The data also support the concept platelet aggregation may be stimulated, directly or indirectly, by hydroxyl radical. The effects of DMSO and glycerol in this study, irrespective of the molecular basis for the effects, may be relevant to the reported therapeutic benefit of these agents in cerebrovascular disease.
Comparison of oculoplethysmography/carotid phonoangiography with duplex scan/spectral analysis in the detection of carotid artery stenosis.
Authors: Keagy B A , Pharr W F , Thomas D , Bowes D E
Published: June 2011

The accuracy of the duplex scan with spectral analysis (DS/SA) in predicting the presence of arteriographic carotid stenosis was compared to that of oculoplethysmography/carotid phonoangiography (OPG/CPA) in 234 vessels from 117 patients who had had both non-invasive studies in addition to independently interpreted arteriograms. The DS/SA with 212/234 (91%) overall correct responses was superior to the OPG/CPA which properly classified 181/234 (77%) of the vessels (p less than .01). Of major clinical impact was the superiority of the DS/SA (p less than .001) in identifying the 72 vessels with 50-99% stenosis. The OPG/CPA had a discouraging 39/72 (54%) false-negative rate in this group whereas the DS/SA missed only 9/72 (12%) of these arteries. Of those 39 incorrect responses for the OPG/CPA, 26/39 (67%) were in patients with a 50% or greater stenosis on the contralateral side. This is a recognized area of weakness for that test. Based on the results of this study, we have abandoned the use of the OPG/CPA in the evaluation of patients with suspected carotid stenosis and rely solely on the duplex scan with spectral analysis.
Phenothiazine-mediated protection of the blood-brain barrier during acute hypertension.
Authors: Johansson B B , Auer L M , Linder L E
Published: June 2011

The phenothiazine dixyrazine (5 mg . kg-1 i.v.) had minimal, transient hypotensive effects but significantly reduced the leakage of 125I labelled serum albumin in conscious rats subjected to acute hypertension provoked by i.v. adrenaline or bicuculline. By contrast, dixyrazine did not protect the blood-brain barrier during osmotic stress induced by intracarotid infusion of 2 M urea. The diameters of pial arteries and veins were continuously measured with a multichannel videoangiometer through a closed cranial window in anesthetized rats before and after i.v. injection of dixyrazine (5 mg . kg-1). No change in vessel diameter was observed except for a transient autoregulatory dilatation of arteries in response to a slight transitory decrease in the blood pressure. It is concluded that dixyrazine probably protects the blood-brain barrier during mechanical stress by modifying the endothelial cell membrane.
Hyperglycemia, recognized and unrecognized, as a risk factor for stroke and transient ischemic attacks.
Authors: Riddle M C , Hart J
Published: June 2011

Glycosylated hemoglobin concentration (GHb), which is considered an indication of glycemia over the preceding several months, was examined in 50 patients hospitalized for recent stroke or transient ischemic attacks (TIA), and compared to that in several reference populations. Patients with stroke or TIA had GHb (mean %A1 +/- SD, 10.2 +/- 2.3) higher than in hospital controls without cerebrovascular disease (8.3 +/- 0.9, p less than 0.005), and equivalent to values for ambulatory diabetic patients treated with diet or diet plus oral agents (9.5 +/- 2.4) or with insulin (10.7 +/- 2.9). Twenty percent (10/50) of the stroke/TIA group were previously known to have abnormal glucose tolerance or diabetes; when this subgroup was excluded, there remained 42% of the original group (21/50) with abnormal GHb (greater than 10% A1) not previously known to have hyperglycemia, and the difference between GHb values for the stroke/TIA patients not known to have glycemic abnormality and for the hospital control group remained significant (p less than 0.005). Sixty-two percent of stroke/TIA patients (31/50) were under treatment for glycemic abnormality, or had high GHb, or both. The high prevalence of elevated GHb in this population could not be attributed to a relationship to age, sex, smoking history, hypercholesterolemia, or hypertension. We conclude that hyperglycemia commonly precedes stroke and TIA, is usually unrecognized, and has been under-appreciated as a risk factor for cerebrovascular disease.
Non-invasive evaluation of patients with extracranial to intracranial bypass.
Authors: Hayes A C , Baker W H , Reichman O H
Published: June 2011

In selected patients with cerebrovascular insufficiency, an extracranial-intracranial bypass is indicated to increase cerebral blood flow. To assess the effect of this operation upon routine non-invasive testing, 15 patients had oculoplethysmography, carotid phonoangiography and Doppler testing. None of those with a preoperative abnormality were changed after surgery, despite angiographically proven anastomotic patency. Whereas non-invasive tests may correctly identify severe internal carotid stenosis, use of these modalities in their routine form does not predict extracranial-intracranial bypass patency.
Ocular pneumoplethysmography and ophthalmodynamometry in the diagnosis of central retinal artery occlusion.
Authors: Wiebers D O , Folger W N , Younge B R
Published: June 2011

Ocular pneumoplethysmography and ophthalmodynamometry measure ophthalmic arterial system pressures to assess noninvasively the hemodynamics of the carotid system. A previously unreported circumstance in which these tests complement one another is central retinal artery occlusion. Typically, the ipsilateral retinal artery pressure, measured by ophthalmodynamometry, is greatly decreased or is zero, whereas the ophthalmic systolic pressure, measured by ocular pneumoplethysmography, is normal.
The natural history of asymptomatic carotid bifurcation plaques.
Authors: Durward Q J , Ferguson G G , Barr H W
Published: June 2011

Seventy-three patients with an angiographically identified asymptomatic stenosis (greater than 50%) and/or ulceration of the common carotid bifurcation have been followed from 6 months to 10 years (average 4 years). All patients had previously undergone contralateral carotid endarterectomy for a transient ischemic attack (TIA) or minor stroke in that carotid territory. During follow-up, 22 patients (30%) developed new symptoms of cerebral ischemia. Twelve developed ischemia referable to the previously asymptomatic side (10 TIA's, 2 strokes). Six developed recurrent ischemic symptoms in the territory of the previously symptomatic and operated carotid artery (2 TIA's, 4 strokes). Five developed ischemia in the vertebro-basilar territory (2 TIA's, 3 strokes). Thirteen patients (17%) died during follow-up, including 6 from cardiovascular disease and 3 from stroke. In our series the incidence of stroke in the territory of a significant asymptomatic carotid plaque was low (3%). Patients were as likely to develop stroke in the territory of a previously operated carotid artery (5%) with asymptomatic carotid lesions is to keep them under review and to consider endarterectomy only if appropriate ischemic symptoms (which are most likely to be TIA's) develop.
Analysis of the gamma ray spectra recorded in the use of Xenon-133 for cerebral blood flow studies.
Authors: Macey D J , Filipow L J , McCarthy S T , Pitkanen M
Published: June 2011

A problem in the measurement of cerebral blood flow with 133Xenon is the presence of extra-cerebral counts in the total counts recorded with a collimated gamma ray detector looking at the brain. A method of studying qualitatively the contribution of this extra-cranial component in patients is described. This entails the sequential accumulation of gamma ray spectra recorded during the clearance phase of 133Xenon from the brain. It is shown that different CBF indices are obtained for various regions of the recorded gamma ray spectra. The principal component of the extra-cerebral counts at 15 minutes postinjection appears to be intra-cranial, and not the scalp as assumed previously in the spectrum subtraction method.
Prognostic significance of severity of carotid atheroma in early manifestations of cerebrovascular disease.
Authors: Harrison M J , Marshall J
Published: June 2011

Two hundred and fifteen patients with transient ischaemic attacks, reversible ischaemic neurological deficit, or completed stroke were studied angiographically. The appearances of the carotid bifurcation were classified as normal, irregular, stenosed or occluded and the possible prognostic significance of the angiographic categories sought in a follow up study. Over a mean follow up period of 4.1 years 12% of patients were found to have died, and 10% had had a stroke. Fourteen percent had TIAs and 5.1% had sustained a myocardial infarction. Mortality and stroke risk were greatest with carotid occlusion which was least often followed by TIAs. Strokes, but not TIAs, were less frequent in the presence of normal angiograms.
Mortality from ischemic heart disease and cerebrovascular disease in Israel 1969-1978.
Authors: Epstein L , Zaaroor M
Published: June 2011

Age standardized mortality data from Ischemic heart disease (IHD) and Cerebrovascular disease (CVD) for the population of Israel were analyzed for the years 1969 to 1978. There has been a clear fall in mortality from both diseases over this period that has been more pronounced in relation to CVD. The mortality from IHD is considerably higher in the total population and in each of the ethnic groups except for those born in North Africa, in whom the difference is small. The mortality in males from IHD is higher than that for females but the reverse is the situation in relation to CVD.
A primate model of chronic cerebral vasospasm.
Authors: Frazee J G
Published: June 2011

Fourteen experiments have been completed to develop an improved primate model of chronic cerebral vasospasm. Results show that by placing a 0.4 mm needle through the intracranial internal carotid artery and percutaneously removing it the following day, cerebral vasospasm is regularly present five days later. There has been no mortality. The results of two monkeys followed with serial angiograms suggest that spasm first appears four days following the subarachnoid hemorrhage and lasts at least eleven days. The results of all experiments show that the most affected vessel in each experiment is reduced to 62% of control diameters. Vasospasm involves cerebral arteries both ipsilateral and contralateral to the site of hemorrhage and extends to the most distal vessels which can be measured. Finally, a neurological defect has been regularly demonstrated on the side contralateral to the site of hemorrhage.
Pentobarbital protection from cerebral infarction without suppression of edema.
Authors: Hoff J T , Nishimura M , Newfield P
Published: June 2011

We studied the mechanism of barbiturate protection from focal cerebral infarction in cats by examining in detail edema formation 72 hours after acute, permanent occlusion of the left middle cerebral artery (LMCA). Neurological function, gas exchange, vital signs, and intracranial pressure (ICP) were observed during the post-occlusion period, and infarct size and cerebral edema were measured after sacrifice. Infarct size was reduced only when pentobarbital was given before occlusion and continued for 24 hours. Edema formation was not suppressed even though the extent of infarction was. Clinical evidence of stroke developed and ICP rose in most cats after occlusion despite the presence of pentobarbital sufficient to reduce infarct size. Elevated ICP accounted for most premature deaths despite intensive cardiopulmonary support. Water and electrolyte changes in the ischemic hemisphere continued to develop throughout the 72 hour post-occlusion period in pentobarbital-treated cats, suggesting that resolution of edema was delayed by the drug. We conclude that pentobarbital reduces infarct size and attenuates the expected time course of ischemic edema in cats, but that the drug has little effect on the severity of edema that develops after arterial occlusion.
Cortical ischemia: effect upon direct cortical response.
Authors: Yamagata S , Carter L P , Erspamer R
Published: June 2011

Correlation of cortical blood flow as measured by a thermal diffusion flow probe (CBFp) with the direct cortical response (DCR) was studied in 48 lightly anesthetized cats with global ischemia. Thresholds for attenuation and loss of DCR were 21.3 +/- 4.7 and 8.7 and 3.4 ml/100 g/min respectively. In abrupt ischemia, CBFp of 0-3 ml/100 g/min produced absence of DCR in 6 min or less; however, at CBFp of 5-10 ml/100 g/min, the time to obliteration of DCR varied from 5 to 180 min. DCR was unlikely to recover after 13 min of 0-2 ml/100 g/min and after 35 min of 4-5 ml/100 g/min. At higher flows, DCR could recover over 60 min or more of ischemia. With gradual production of ischemia, flows less than 20 ml/100 g/min for over 60 min had a detrimental effect upon recovery of DCR if DCR was lost for 7.5 min or more. Some evidence that implied adaptability of the cortex to ischemia was found.
Undiagnosed syncope: search for an arrhythmic etiology.
Authors: Klein G J , Gulamhusein S S
Published: June 2011

Patients with recurrent, unheralded syncope are often suspected of having intermittent cardiac bradyarrhythmias or tachyarrhythmias. However, syncopal episodes may be infrequent and investigations may yield few or non-specific etiological clues. Therapy may be entirely empirical (pacing or antiarrhythmic drugs) or guided by an abnormality detected that suggests a particular diagnosis. Intracardiac electrophysiological studies may detect conduction abnormalities or provoke arrhythmias but the relationship between these findings and clinical symptoms may be difficult to establish. The recording of the ECG during syncope by repeated ambulatory monitoring or other methods remains the only unequivocal diagnostic technique to establish an arrhythmic etiology.
Redistribution of cerebral blood flow following STA-MCA by-pass in patients with hemispheric ischemia.
Authors: Meyer J S , Nakajima S , Okabe T , Amano T , Centeno R , Len Y Y , Levine J , Levinthal R , Rose J
Published: June 2011

Regional cerebral blood flow and vasomotor reactivity were measured in 33 patients with surgically remediable hemispheric ischemia by the 133Xe inhalation method prior to superficial temporal to middle cerebral artery (STA-MCA) by-pass. Thirteen patients also underwent LCBF and L lambda measurements by the stable xenon CT method for comparison. Twenty-four had proximal occlusion of one or both internal carotid arteries, 9 had intracranial occlusive disease (4 internal carotid, 5 middle cerebral). Measurements were repeated at intervals up to 30 months following surgery and compared to measurements in a similar group (N = 13) treated medically. In the surgically treated group 22 patients had recurrent TIAs, of whom 12 also had minor residual neurological deficits from recent small cerebral infarctions with potential for recovery (RINDs) while the remaining 11 had RINDs without TIAs. After surgery 28 improved with cessation of TIAs and/or neurological recovery, 3 remained unchanged, 2 cases worsened. Compared to age-matched normal hemispheric F1 (gray matter) values, pre-operative F1 values in the STA-MCA group were reduced in both ischemic and opposite hemispheres. Ischemic regions showed imparied vasomotor reactivity to 5% CO2 or 100% O2 inhalation. After surgery, mean hemispheric F1 values increased + 12.8% on the by-pass side and + 10.5% on the contralateral side. Mean F1 increases reached a maximum 3 months after by-pass, most evident in ipsilateral frontal regions (+ 24.2%). Vasomotor reactivity did not significantly improve. Medically treated cases did not show similar F1 increases. Thirteen with carotid occlusive disease (8 with TIAs, 5 with small recent infarcts) underwent CT LCBF and L lambda measurements before and after STA-MCA by-pass. Cases with recent infarcts showed reduced LCBF and L lambda values which increased significantly after STA-MCA by-pass, however the total group operated upon showed only trends for CBF increases, probably due to large standard deviations encountered in serial measurements.
Sympathetic nerve terminals in the tunica media of human superficial temporal and middle cerebral arteries: wet histofluorescence.
Authors: Akiguchi I , Fukuyama H , Kameyama M , Koyama T , Kimura H , Maeda T
Published: June 2011

In specimens from the superficial temporal artery (STA) and middle cerebral artery (MCA), obtained during STA-MCA anastomosis, green fluorescent varicose fibers of sympathetic nerves were clearly visible with both formaldehyde-glutaraldehyde and sucrose-potassium phosphate-glyoxylic acid wet-histofluorescent techniques. These fibers were fairly thick, were densely packed and had a meshwork-like arrangement. Fluorescent terminals were seen both in the adventitia and in the outer muscular layer of the media in both STA and MCA specimens. They were more often observed in patients with prominent atherosclerosis in these vessels. The present study suggests the possible role of sympathetic nerve terminals in the development of vasospasm and occlusive lesions in cerebral vessels. It may also help to explain the marked constriction and transient occlusion following a STA-MCA bypass procedure.
Analysis of reproducibility and sensitivity of atraumatic measurements of regional cerebral blood flow in cerebrovascular diseases.
Authors: Meric P , Luft A , Seylaz J , Mamo H
Published: June 2011

We tested the reproducibility of consecutive measurements of regional cerebral blood flow (rCBF) made in 13 areas of each hemisphere in patients with cerebrovascular diseases by the atraumatic 133Xe intravenous injection method. The data were analysed by a two-compartment model similar to that used in the Obrist inhalation method. Four parameters derived from the model were tested: Fg (flow of the fast-clearing compartment), FF and W (respectively fractional flow and relative tissue weight of the same compartment), ISI (initial slope index as defined by Risberg et al.). No significant variation was found in these four parameters between two consecutive rest measurements for all the areas studied and whatever the time interval between the measurements. The variances of the differences of Fg and ISI between the two measurements were found to be similar to those found in normal healthy subjects. The variances of FF and, consequently, W were greater than the values determined in healthy volunteers. An attempt to improve the quality of the results, by correcting them for the effects of PaCO2 changes between the measurements, resulted on the contrary in a general increase of the variances of the differences, showing the inadequacy of the correction coefficients used for healthy subjects at least for a proportion of the patients with cerebrovascular diseases. Sensitivity, tested by activation (hand work), shows a positive answer for FG but no significant change in ISI in any area. These findings demonstrate that in cases of cerebrovascular diseases the raw data (uncorrected for the changes in PaCO2) are the most reliable data but the meaning of the values found for FF and W must be regarded with caution since they may be affected by the "slippage" phenomenon. It is suggested that the ISI should only be used when there is evidence of a failure of the compartmental model, but only as a rough estimation of the flow level because of its lack of sensitivity.
Treatment of acute focal cerebral ischemia with prostacyclin.
Authors: Awad I , Little J R , Lucas F , Skrinska V , Slugg R , Lesser R P
Published: June 2011

The object of this investigation was to study the effects of prostacyclin (PGI2) upon the evolution of acute focal cerebral ischemia in the cat. Twenty-five fasted adult cats, lightly anesthetized with nitrous oxide, underwent right middle cerebral artery (MCA) occlusion. Eleven cats received an intracarotid infusion of PGI2 in buffered saline pH 10.5 (100 ng/kg/min at 0.01 ml/kg/min), and 11 cats received intracarotid buffered saline pH 10.5 (0.01 ml/kg/min) without therapeutic agents. Treatment with PGI2 was started upon MCA occlusion and continued for 6 hours. Thirty minutes prior to perfusion, the animals were given fluorescein and Evans blue by intravenous injection. The cats were perfused-fixed in vivo with carbon and buffered formalin 6 hours after MCA occlusion. Another 3 cats received tritium labeled intracarotid PGI2, and peripheral venous samples were collected and assayed for PGI2 plasma levels. Mean arterial pressure was stable in PGI2 treated animals during 6 hours of MCA occlusion, while untreated cats had significant progressive hypertension during that period. The rCBF (measured by the intracarotid 133Xe method) decreased markedly in all animals immediately upon MCA occlusion. However, untreated animals had a significant progressive improvement in rCBF during the occlusion period, while PGI2 treated animals had no such improvement. Quantitative EEG changes, gross edema, areas of fluorescein extravasation, patterns of carbon perfusion, and infarct size were not significantly different in the two groups. While most untreated animals had marked Evans blue extravasation after 6 hours of MCA occlusion, most PGI2 treated animals had no such extravasation, indicating some protection of the blood-brain barrier in these animals.
Effects of vasoconstriction and distal dilation on carotid stenoses in the dog.
Authors: Santamore W P , Wood J H , Bove A A , Lawner P M
Published: June 2011

Traditionally, arterial stenoses have been assumed to be inflexible, static obstructive lesions that could not acutely change their configuration or cross-sectional area. However, recent clinical and experimental observations have shown that coronary arterial stenoses can respond to vasoconstriction and intraluminal pressure changes. This experimental study evaluated whether similar dynamic changes could occur in a carotid artery stenosis. The effects of dilation distal to a circumferential snare were examined in 6 mongrel dogs. To eliminate collateral flow, the distal carotid artery was occluded and blood flow diverted through a 16 or 20 gauge needle. With no stenosis, distal dilation increased flow from 29.0 +/- 2.0 to 90.1 +/- 3.8 ml/min, (p less than 0.01). With moderate stenosis, the flow increase (25.5 +/- 1.3 to 56.4 +/- 3.7 ml/min, p less than 0.01 following dilation was attenuated. With severe stenosis, flow paradoxically decreased (20.4 +/- 1.0 to 11.4 +/- 1.0 ml/min, (p less than 0.01). This flow decrease was associated with a large stenotic resistance increase (2.13 +/- 0.51 to 18.93 +/- 5.58 mm Hg/ml . min-1, (p less than 0.01). In eight additional experiments, an in vitro preparation was used to examine the effects of vasoconstriction on stenotic severity. Vasoconstriction, induced by ergonovine, methoxamine, angiotensin, or vasopressin, resulted in a significant flow decrease and stenotic resistance increase. Thus, both vasoconstriction and intraluminal pressure were shown to affect stenotic severity, and thereby influence blood flow. These data illustrate hemodynamic factors which may be important in patients with severe carotid artery stenosis.
A small animal model for electrocardiographic abnormalities observed after an experimental subarachnoid hemorrhage.
Authors: Lacy P S , Earle A M
Published: June 2011

The male Sprague-Dawley rat was successfully used to produce increases in arterial blood pressure and electrocardiographic abnormalities similar to those seen in patients after a subarachnoid hemorrhage. The model employs a less expensive, easily available laboratory animal than other existing models. Whole heparinized blood is introduced in the area of the circle of Willis to simulate a subarachnoid hemorrhage. This model ensures a constant body-blood volume and minimizes damage to brain tissue as no blood vessel has to be punctured. The volume of blood required to produce bradycardia and other electrocardiographic abnormalities can be controlled and calculated for each animal. The model produced a sudden onset and progression of cardiovascular symptoms. Blood apparently is specific for producing electrocardiographic abnormalities as compared to 0.9% saline, Dextran 40 and Gentran 75 when introduced in the area of the circle of Willis. This specificity was not maintained when blood and saline were introduced into the cisterna magna as electrocardiographic abnormalities were observed with both agents.
Production of cyclic nucleotides from normal human brain.
Authors: Naito E , Shimoji K , Endoh H , Ichikawa T , Hashiba M
Published: June 2011

Concentrations of cyclic AMP and cyclic GMP in arterial and internal jugular venous (IJV) blood were determined at the resting wakeful state in thirty surgical patients without neurological deficits. The levels of cyclic AMP in artery and IJV were 32.1 +/- 3.0 and 40.0 +/- 4.1 pmol/ml (means +/- standard errors), respectively, while those of cyclic GMP in artery and IJV were 12.2 +/- 2.7 and 14.4 +/- 3.0 pmol/ml, respectively. Concentrations of both cyclic nucleotides in IJV were significantly higher (P less than 0.001) than those in artery. IJV-arterial differences for cAMP and cGMP were 7.9 +/- 1.7 and 2.1 +/- 0.5 pmol/ml, respectively. The results indicate that both cyclic nucleotides are constantly produced and released from the normal human brain.
Oxypurines in cerebrospinal fluid as indices of disturbed brain metabolism. A clinical study of ischemic brain diseases.
Authors: Hällgren R , Niklasson F , Terent A , Akerblom A , Widerlöv E
Published: June 2011

Using a HPLC method the concentrations of oxypurines were simultaneously measured in CSF of patients with acute cerebrovascular lesions (CVL) and global cerebral ischemia (GCI) in an attempt to study disturbed brain metabolism during cerebral oxygen deprivation. In cerebral infarction both hypoxanthine and xanthine gradually increased from normal levels at admission to pathologically increased on the fourth day from onset of symptoms. There was no correlation between these substances and the clinical score but the maximum CSF-hypoxanthine concentration was significantly correlated to the maximum lesion volume determined by computerized tomography. In GCI the hypoxanthine-xanthine concentrations were considerably increased less than 20 hours from onset of unconsciousness but the initial levels did not predict the final outcome. These findings suggest that the end products of nucleotide degradation accumulate rapidly in acute cerebral hypoxia but more gradually in CVL probably due to growing local edema with subsequent local hypoxia. In controls and patients with CVL the CSF-urate concentrations were positively correlated to those of CSF-albumin. However, in CVL the increase of urate was relatively much more pronounced than the increase of albumin indicating that urate is a sensitive marker of dysfunction of blood-brain barrier.
Rapid, transient drop in brain glucose after intravenous phloretin or 3-0-methyl-D-glucose.
Authors: Oldendorf W H , Crane P D , Lawner P M , Braun L D
Published: June 2011

Rats were injected intravenously with either phloretin (100 mg/kg) or 3-0-methyl glucose (2 g/kg) to reduce the carrier-mediated flux of glucose into brain. Plasma glucose and brain free glucose (BFG), lactate, and glycogen were measured over a 16 min time course. Injection of these substances caused a rapid drop in BFG to 60% of control at one minute and a minimum (50% of control values) at 4 min., followed by a gradual rise to control levels at 16 min. While plasma glucose fell, and then increased after injection, brain lactate and glycogen content was unaffected. Repeated injections of phloretin eventually caused a drop in brain glycogen; but with either competitor, BFG never fell below 50% of normal values. The i.v. injection of the glucose analog, 3-0-methyl glucose (the less toxic of the two drugs) is proposed as a possible means of cutting off the potentially hazardous supply of blood glucose to the postischemic brain.
Diagnostic evaluation of degenerative and vascular dementia.
Authors: Loeb C , Gandolfo C
Published: June 2011

The accuracy of the Ischemic Score (IS) of Hachinski in the differential diagnosis between senile dementia (SDAT) and multi-infarct dementia (MID) is evaluated in this study. Ninety-four demented patients were subdivided on the basis of CT scan in three subgroups: 1) CT-SDAT (ventricular enlargement and widening of cortical sulci), 2) CT-MID (multiple low density areas attributable to ischemic lesions), 3) CT-VASC (single low density area attributable to ischemic lesion). Sixty-nine percent of patients with SDAT and 94% of patients with MID had an Ischemic Score in agreement with the diagnosis established by CT scan. With the purpose of improving the accuracy of the I.S., a modified ischemic score consisting of five items (abrupt onset; history of strokes; focal symptoms; focal signs; focal (single or multiple) CT-low density areas) is proposed as a useful tool in the differential diagnosis between SDAT and MID.
Usefulness of the measurement of plasma beta-thromboglobulin (beta-TG) in cerebrovascular disease.
Authors: Taomoto K , Asada M , Kanazawa Y , Matsumoto S
Published: June 2011

The plasma concentration of the platelet-specific protein beta-thromboglobulin (beta-TG) was measured in 39 normal subjects and 568 patients of neurological diseases. The beta-TG RIA commercially available KIT was also evaluated. Abnormally high plasma levels of beta-TG were demonstrated in groups of ischemic or obstructive cerebrovascular diseases as compared with that of normal subjects. The highest concentrations were found in 8 patients with Moya-Moya disease, (mean concentration of beta-TG was 204.4 ng/ml), completed stroke at an acute stage was next (mean beta-TG level was 194.8 +/- 70.8 ng/ml). On the other hand, many hemorrhagic cerebro-vascular diseases or other neurological diseases such as brain tumors, hydrocephalus, etc. do not show elevated beta-TG levels. In many patients with ischemic or obstructive cerebro-vascular diseases treated with anti-platelet drugs such as Aspirin, Dipyridamole, Bencyclane or Ticlopidine, a significant fall in plasma concentration of beta-TG was chronologically demonstrated. The measurement of plasma beta-TG concentration may be useful not only in the diagnosis of ischemic or obstructive cerebro-vascular disorders but also in judging the efficacy of anti-platelet therapies and prognosis.
Influence of echocardiography on management of patients with systemic emboli.
Authors: Robbins J A , Sagar K B , French M , Smith P J
Published: June 2011

To determine the impact of echocardiography in management of patients with systemic embolism, we retrospectively reviewed medical records and echocardiograms of 191 consecutive patients with suspected systemic embolism. One hundred sixteen patients had two dimensional echocardiograms and 75 patients had M-mode echocardiograms only. Patients were divided into three groups: Group 1 had no cardiovascular disease; Group 2 had cardiovascular disease, and Group 3 had hypertension only. Changes in therapy following echocardiogram were defined as initiation or discontinuation of anticoagulants or antiplatelet agents, cardioversion, or surgical intervention. M-mode echocardiogram did not identify any heart as a likely source of systemic embolism. Two dimensional echocardiogram defined 13 hearts as likely sources of emboli. All of these patients had known cardiovascular disease. Four of 13 patients (30.7%) whose hearts were likely sources of emboli had a change in therapy compared with 42 of 126 patients (33.3%) with low probability echocardiograms. We conclude that M-mode echocardiogram has no role in evaluation of patients with systemic emboli. Two dimensional echocardiogram may identify the heart as a source of emboli in patients with cardiovascular disease but does not alter early management.
Effect of blood pressure on prevalence of carotid atheroma.
Authors: Harrison M J , Wilson L A
Published: June 2011

In an attempt to elucidate the mechanism by which hypertension acts as a risk factor for major non-haemorrhagic stroke, its effect on the prevalence of carotid atheroma has been studied angiographically. The carotid angiograms of 269 patients with cerebral tumours have been reviewed for evidence of coincidental atheromatous change. The prevalence of signs of arterial disease at the carotid bifurcation proved to be greater amongst patients with an elevated casual blood pressure reading, though the effect was small and confined to subjects over 50 years of age. It is argued that other factors must contribute to the connection between hypertension and the risks of cerebral infarction.
Experimental cerebral vasospasm. Part 2. Contractility of spastic arterial wall.
Authors: Nagasawa S , Handa H , Naruo Y , Watanabe H , Moritake K , Hayashi K
Published: June 2011

We studied the mechanical properties of canine basilar arteries subjected to experimental subarachnoid hemorrhage (SAH). Smooth muscle contractility was determined from pressure-diameter curves obtained after subjecting the basilar arteries to three different conditions: Krebs-Ringer solution (KRS), Krebs-Ringer solution containing serotonin (5HT), and saline solution. Pressure-diameter curves obtained in KRS and 5HT are biphasic and have sharp flexions that yield flexion points. The pressure level at the flexion point increases as vasospasm increases. Strong constriction is retained up to that pressure above which the constriction is released abruptly. These data suggest that increasing the intraluminal pressure dilates the spastic artery nonlinearly and that induced hypertension could relieve the cerebral ischemia caused by vasospasm if blood pressure were maintained above the flexion point. The contractile response of spastic arterial wall to serotonin remains unchanged after SAH although the spastic constriction increases progressively and becomes maximal seven days after SAH. The lesser the arterial wall stiffness, the more efficiently it constricts. This means that the diminution of arterial stiffness observed after SAH might be one of the factors promoting the development of vasospasm.
Anticoagulation in cerebral ischemia.
Authors: Weksler B B , Lewin M
Published: June 2011

Anticoagulation clearly benefits patients at risk of stroke from cerebral embolism. Conversely, patients with completed ischemic stroke are not benefited, and may show a higher mortality and morbidity because of hemorrhagic complications. Technical advances in the early, accurate diagnosis of cerebral hemorrhage, the constant infusion of heparin, and closer monitoring of anticoagulation have continued to reduce the risk of hemorrhage in treated patients. In patients with TIA, alternative therapy with anti-platelet agents, which appears to prevent stroke at less bleeding risk, is under study. Current results show no differences between the two therapies, but only historical controls are available for evaluation of benefit. Whether or not anticoagulation prevents progression of neurologic deficit in patients with strokes-in-evolution remains an unanswered question, which can be resolved only by prospective, randomized, controlled trials.
Treatment after transient ischemic attacks: a comparison between anticoagulant drug and inhibition of platelet aggregation.
Authors: Gårde A , Samuelsson K , Fahlgren H , Hedberg E , Hjerne L G , Ostman J
Published: June 2011

Treatment with an anticoagulant (AC) or acetylsalicylic acid (ASA), chosen at random, was given to 241 patients with symptoms of carotid transient attacks of ischemia, some of whom recovered completely within 24 hours (TIA) while the others had slight residual symptoms (TIA-IR). Cerebral infarction was recorded in 4 patients in each of these treatment groups during a mean follow-up period of 20 months. The incidences of TIA and TIA-IR were also similar in the two groups. Severe hemorrhage occurred more often in the AC group, whereas other side reactions, including gastrointestinal disorders, were more common in the ASA group. Recurrent cerebral ischemic events were significantly more common among the patients that had had greater than or equal to 2 TIAs in the 14 days immediately preceding randomization, and in those with a history of CVS symptoms more than 14 days before randomization, or those with a carotid bruits. In the group experiencing greater than or equal to 2 TIAs in the 14 days prior to randomization the incidence of recurrent cerebral ischemic events was the same for the two types of treatment.
No effect of prostacyclin on blood flow, regulation of blood flow and blood coagulation following global cerebral ischemia.
Authors: van den Kerckhoff W , Hossmann K A , Hossmann V
Published: June 2011

In normothermic cats under light barbiturate anesthesia, cerebral blood flow was arrested for one hour by intrathoracal occlusion of the innominate, the left subclavian, and both mammary arteries. Recirculation of the brain after ischemia resulted in reactive hyperemia, followed by a decrease of blood flow to about 70% of control (post-ischemic hypoperfusion). During postischemic hypoperfusion, CO2-reactivity was completely abolished. Intravenous infusion of prostacyclin 2 hours after ischemia (1.8 micrograms/kg/min) decreased systemic arterial blood pressure and reduced platelet aggregability but did not improve cerebral blood flow, did not restore CO2-reactivity, and did not influence postischemic changes of blood coagulation. It is concluded that prostacyclin deficiency is not or not the only reason for the development of post-ischemic hypoperfusion and the associated disturbance of flow regulation.
111-Indium platelet imaging, Doppler spectral analysis and angiography compared in patients with transient cerebral ischaemia.
Authors: Goldman M , Leung J O , Aukland A , Hawker R J , Drolc Z , McCollum C N
Published: June 2011

We have evaluated carotid gamma imaging using 111Indium-labelled platelets in the diagnosis of carotid artery disease and measured the accumulation of labelled platelets on endarterectomy specimens. Autologous 111In labelled platelets were injected in 25 patients with TIA. Gamma images were then taken daily and independently interpreted by two observers. Carotid endarterectomy was performed in 11 patients allowing measurement of the radioactivity on the operative specimen. These results were compared to the findings on angiography and Doppler spectral analysis. All endarterectomy specimens accumulated platelets with the most active equivalent to platelets from 1.8 ml blood. Atheromatous ulcers were more active than stenoses with mean (+/- SEM) activities of 1.12 +/- 0.37 and 0.38 +/- 0.10 respectively. These radioactivity levels were at the threshold of gamma camera resolution in a theoretical model. Both observers agreed that 22 of the 50 carotid bifurcations showed platelet accumulation on gamma imaging. Of the 12 atheromatous ulcers demonstrated by angiography 11 were visualized, but only five of ten stenoses greater than 80% were detected. As Doppler identified all stenoses only one angiographically diseased carotid was not detected by combining ultrasound with platelet scanning. Atherosclerotic arteries accumulate 111In platelets and the more thrombogenic ulcerated plaques are identified more frequently than stenoses. Long-term follow-up is required to establish the clinical relevance of platelet deposition.