bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Ischemia in Dogs: Cerebrovascular CO
2
Reactivity and Autoregulation
Authors: NEMOTO EDWIN M. , SNYDER JAMES V. , CARROLL ROBERT G. , MORITA HIDEO
Published: June 2011

One hypothesis on the pathogenesis of post-ischemic-anoxic encephalopathy is impaired cerebral perfusion or the no-reflow phenomenon. Therapies aimed at preventing the development of this phenomenon are increased cerebral perfusion pressure (CPP) and hyperventilation or hypercapnia. Using a dog model in which we have described the progressive development of post-ischemic (PI) cerebral hypoperfusion after 15 minutes of global ischemia induced by aortic and vena cavae clamping, our aims in this study were to determine during the PI cerebral hypoperfusion period: (1) cerebrovascular reactivity to CO
2
, and (2) cerebral blood flow (CBF) autoregulation. Post-ischemic cerebral hypoperfusion to about 50% of normal was not accompanied by raised intracranial pressure (ICP) but cerebrovascular CO
2
reactivity was markedly attenuated while maintaining some kind of autoregulatory phenomenon. Cerebral uptake of oxygen was not significantly affected by changing Pa

co
co2

from 20 to 60 torr at constant CPP or by changing CPP from 64 to 104 torr at constant Pa

co
co2

. These results suggest that increasing both CPP and hypocapnia/hypercapnia would not significantly attenuate PI neurological deficit after global cerebral ischemia. However, in two dogs inadvertently hemodiluted in the PI period, increasing CPP from 50 to 200 torr increased CBF by 200%, suggesting that hemodilution plus increased CPP may be effective therapy for amelioration of post-ischemic-anoxic encephalopathy. The significance of our findings on cerebrovascular CO
2
reactivity and autoregulation with respect to the mechanism of the no-reflow phenomenon is discussed.
Comparison of Blood Flow and Patency in Arterial and Vein Grafts to Basilar Artery
Authors: WHANG C. J. , MOZINGO J. ROBERT , RHOTON A. L.
Published: June 2011

Blood flow and patency rates obtained by lingual to basilar artery anastomosis were compared with those obtained by saphenous vein bypass graft from the carotid to the basilar artery in two groups of ten dogs. Flow was measured by an electromagnetic technique while blood pressure and blood gases were monitored. Graft patency also was determined by angiography and histological examination. The arterial and venous grafts carried more than enough blood to maintain a normal flow (9.5 ml per minute) through the basilar system of dogs.

Immediately after anastomosis, average flow through the vein grafts was 15.5 ml per minute (range 10 to 20 ml per minute) and through the arterial anastomosis 15.6 ml per minute (range 10 to 24 ml per minute). Six weeks later, average flow through the vein graft was 11.5 ml per minute and through the arterial graft 13 ml per minute. With induced hypertension, flow increased in the arterial grafts to an average of 26.2 ml per minute and in the vein grafts 24 ml per minute. Hypercarbia increased arterial graft flow to an average of 27.8 ml per minute and vein graft flow to 23.5 ml per minute.

By angiography, graft patency was shown in only 80% of the grafts at one week and in 60% at six weeks postoperatively, even though all grafts were patent by flow and histological determinations. This failure of angiography represents a limitation of the radiographical resolution in millimeter-sized vessels.
Chronically Impaired Autoregulation of Cerebral Blood Flow in Long-Term Diabetics
Authors: BENTSEN NIELS , LARSEN BO , LASSIN NIELS A.
Published: June 2011

Using the arteriovenous oxygen difference method autoregulation of cerebral blood flow (CBF) was tested in 16 long-term diabetics and eight control patients. Blood pressure was raise by angiotensin infusion and lowered by trimethaphan camsylate infusion, in some cases combined with head-up tilting of the patient. Regression analysis was carried out on the results in order to quantify autoregulatory capacity.

In the control patients CBF did not vary with moderate blood pressure variations, indicating normal autoregulation. In four of the 16 diabetic patients CBF showed significant pressure dependency, indicating impaired autoregulation. The cause of impaired autoregulation in some long-term diabetics is believed to be diffuse or multifocal dysfunction of cerebral arterioles due to diabetic vascular disease. Other conditions with impaired autoregulation are discussed and compared with that seen in long-term diabetes.
Comparative Study of Cerebral Vasoactivity in Vascular Sclerosis of the Brain in Elderly Men
Authors: DEKONINCK W. J. , COLLARD M. , JACQUY J.
Published: June 2011

Thirty-five elderly patients underwent a systematic series of cerebrovascular examinations. The patients were divided into three groups on the basis of clinical criteria: normal patients (Group 1), patients with sequelae of a previous stroke or with minor mental disorders (Group 2), and patients with arteriosclerosis dementia (Group 3). The vasomotor reactions of the cerebral arteries were investigated by estimating regional cerebral blood flow (
133
Xe clearance technique). The authors emphasize the existence of cerebral vasoreactivity in subjects with clinical symptoms of senile dementia. Furthermore, in each of the three groups of elderly patients, there seemed to be a lack of correlation between the clinical symptoms and certain specific vascular examinations.
Energy Metabolism During Brain Ischemia
Authors: YATSU FRANK M. , LEE L-W , LIAO C-L
Published: June 2011

The permissible duration of brain ischemia without sustaining damage is short. Less clear are the mechanisms accounting for the vulnerability of brain to ischemic insults. Neurochemical factors implicated include impairment of energy synthesis by mitochondria and of energy-dependent processes such as synaptic transmission, ATPase activity, membrane conductance and altered protein and lipid synthesis. To clarify the vulnerability of energy metabolism, we investigated energy availability and synthesis in our model of global cerebral ischemia. Our studies evaluated in vitro mitochondrial ATP synthesis and the in vivo quantitation of the cortical adenylate pool. Results of our investigations support a growing body of evidence showing the energy state to be relatively stable to ischemia. We conclude that an energy-dependent process of brain is primarily vulnerable to ischemia.
Trace Metal Content of Cerebral Vessels in American Blacks, Caucasians and Nigerian Africans
Authors: TAYLOR G. OLADUNNI , WILLIAMS A. OLUFEMI , RESCH J. A. , BARBER J. B. , JACKSON M. A. , PAULISSEN G. A.
Published: June 2011

Trace metal contents of cerebral vessels in age-matched and sex-matched subjects from three population groups were estimated. The trace metals estimated included calcium, manganese, zinc, magnesium, copper and iron. The American blacks in Washington, D.C., who are ethnologically related to Nigerian Africans, have different patterns of trace metal contents in their cerebral vessels and the observed levels also differed in some respects from Minnesota Caucasians living in a similar environment. The greatest amounts of calcium, zinc, and copper were found in the vessels of American blacks while the greatest amount of magnesium was found in vessels of Minnesota Caucasians. There was no statistically significant difference in the manganese content of the cerebral vessels in the three population groups. Nigerian Africans had the least amounts of copper and magnesium but had the highest iron content. A similar high level of iron was observed in the vessels of American blacks. Since it has been shown that American blacks have the most extensive and severe degree of atherosclerosis among the three population groups, it would appear that iron, calcium and manganese in the cerebral vessels may not directly relate to the severity of cerebral atherosclerosis. Relatively high levels of copper and magnesium, which were observed in the cerebral vessels of American blacks and Caucasians, may be of significance in the pathogenesis of cerebral atherosclerosis. The low levels of the trace metals in Nigerians may be protective. The possible role of zinc requires further studies.
Geographic differences in mortality from stroke in North Caroline. 1. Analysis of death certificates.
Authors: Heyman A , Tyroler H A , Cassel J C , O'Fallon W M , Davis L , Muhlbaier L
Published: June 2011

Analysis of death certification in North Carolina for a three-year period, 1969 through 1971, showed regional differences in mortality rates from stroke in white men, with the highest rates in the Plains (tobacco growing and farming) area and the lowest rates in the Mountain region. These geographic differences in death rates were observed in all but the youngest age decade and also in the various types of stroke, i.e., hemorrhagic and occlusive cerebrovascular diseases. This regional variation in mortality, however, was not present in white women or blacks. The prevalence at death of heart disease, hypertension and diabetes also was higher in the Plains than in the Mountain region, suggesting that the observed geographic variation of stroke mortality is related to one or more of these major risk factors. It is concluded that the geographic differences in stroke mortality, which had been reported during previous decades, are real and are not due to variations in death certification, errors in diagnosis, or other explanations that might artificially produce inaccuracies in vital statistics.
Platelet survival studies in stroke-prone spontaneously hypertensive rats (SHRSP).
Authors: Okuma M , Yamori Y
Published: June 2011

Platelet survival was studied by using 51Cr-labeled platelets in stroke-prone spontaneously hypertensive rats (SHRSP), stroke-resistant SHR (SHRSR) and normotensive control rats of the Wistar-Kyoto (WK) strain. Relatively young animals of the same age prior to the development of cerebrovascular lesions (cerebral infarction and/or hemorrhage) were used. Platelet half-life time in SHRSP was slightly but significantly shorter than in any other groups or rats, irrespective of the type of platelet donors. Mean platelet consumption was also significantly increased in SHRSP only. Platelets of SHRSP injected into SHRSR showed normal survival. These data support the concept that the shortened platelet survival in SHRSP is brought about by some extracorpuscular abnormalities. Although the vascular changes in SHRSP could be the most likely explanation for the shortened platelet survival, its mechanism remains to be solved. This investigation suggests that studies of the platelet survival in hypertension may be useful in predicting the development of stroke before its clinical recognition.
Ischemic Brain Edema and Compression Brain Edema
Authors: YAMAGUCHI MICHIO , SHIRAKATA SEIYA , YAMASAKI SYUN , MATSUMOTO SATOSHI
Published: June 2011

Two experimental models of brain edema have been produced in rats. Some animals underwent bilateral carotid artery ligation (BLCL), while others received extradural compression by a rubber bar. The characteristics of these conditions were compared by Evans blue injection and by the colloidal carbon perfusion method. Although both models produced an increase in the water content of brain tissue, a blood-brain barrier leak to Evans blue was observed only in the compression edema model. The steroid drug, hydrocortisone, diminished the water content of the edematous brain caused by compression but had no effect on that produced by BLCL. The cerebral circulation, as studied by colloidal carbon perfusion, revealed a vasodilation pattern in those animals who underwent bilateral carotid artery ligation, while vascular damage was observed in the compression edema model.
Neurogenic Regulation of Cerebral Blood Flow Following Ischemia
Authors: ZERVAS NICHOLAS T. , HORI HIROSHI , NAGORO MAKATO , WURTMAN RICHARD
Published: June 2011

To elicit evidence concerning neurogenic control, regional cerebral blood flow determined by measurement of cortical temperature was examined in monkeys. Following three hours of temporary occlusion of the MCA, pressure autoregulation was preserved in all control animals. Presumptive partial chemical sympathectomy, produced by the administration of either L-alphamethyl-tyrosine or 3-alpha-dimethyl-tyrosine methyl ester HCl, was associated with loss of pressure autoregulation following 1.5 hours of occlusion of the MCA on only the side of the occlusion. Failure of pressure autoregulation in the treated animals implies that sympathetic control was a partial requirement of proper postischemic pressure autoregulation.
Limitations of diazoxide reversal of vasospasm.
Authors: Heros R C , Lavyne M H , Zervas N T
Published: June 2011

Diazoxide failed to safely relieve cerebral vasospasm by intracisternal injections in dogs and by intracarotid injections in monkeys despite in vitro documentation of arterial relaxation with this agent. Administration of the drug frequently produced hypotension and, in the presence of vasospasm, was associated with a high mortality rate.
An in vitro study of prolonged vasospasm of a rabbit cerebral artery.
Authors: Duckles S P , Bevan R D , Bevan J A
Published: June 2011

Longitudinal stretch of the rabbit basilar artery produces local injury followed by prolonged circular constriction. After stretching and rapid release in vitro localized constrictions promptly occurred. This could be prevented by prior treatment with cyanide or calcium-free solution. Once produced, constrictions persisted for more than 72 hours. Previously induced constriction was not reversed by treatment for two hours with cyanide or by removing calcium. Histological observation indicated that constricted areas were associated with a discrete circumferential rupture of the internal elastic lamina and disruption and thinning of the underlying media. Specific catecholamine fluorescence at the adventitio-medial junction was unchanged in constricted areas. The relationship between smooth muscle cell length and resting tension of artery segments with and without constrictions was compared. Segments with constrictions had a shorter muscle length for any given resting tension, which confirms that constriction was not due to passive collapse of the vessel wall. These findings suggest that injury of cerebrovascular smooth muscle may result in essentially irreversible vasoconstriction. Such a mechanism could contribute to the pathogenesis of prolonged cerebral vasospasm after SAH or traumatic injury to the cerebrum.
Abnormal cerebrovascular response to altered PaCO2 in baboons with obstructive jaundice.
Authors: McCalden T A , Eidelman B H , Bloom D
Published: June 2011

The cerebrovascular response to hypercapnia and hyperventilation was studied in normal and jaundiced baboons by the intracarotid 133Xe injection technique. The baboons with bile duct ligation were found to have decreased CBF at all levels of PaCO2. This difference between normal and jaundiced baboons was 13% at normocapnia rising to 33% with hypercapnia and 37% with hypocapnia. The CBF values all were increased toward normal by use of an alpha-adrenoreceptor blockade (phentolamine). It is suggested that the obstructive jaundice potentiated an inherent vasoconstrictor alpha-adrenergic mechanism to oppose the effects of CO2. Also, alteration of the PaCO2 may have produced its effects on the cerebral vessels by altering this adrenergic mechanism.
Effect of anticoagulants and inhibitors of platelet aggregation on thrombotic occlusion of endarterectomized cat carotid arteries.
Authors: Piegras D G , Sundt T M , Didisheim P
Published: June 2011

Cat carotid arteries measuring 1.8 to 2 mm in diameter were endarterectomized under the operating microscope over a 1-cm segment and the arteriotomy was closed with a 9-0 monofilament nylon suture. Vessels exhibiting significant narrowing of the lumen due to faulty closure of the arteriotomy were excluded from the study. The vessels were divided into six groups according to the method of treatment of the animals: control, aspirin, Coumadin, Coumadin plus aspirin, heparin for less than four hours, and heparin for four to eight hours. All vessels in the untreated group subjected to simple arteriotomy and closure remained patent. Only heparin demonstrated an apparent beneficial effect after endarterectomy with 100% of the vessels treated more than four hours and 30% of those treated less than four hours remaining patent. This is contrasted to a 0% patency in other endarterectomized vessels.
Pial arteriolar responses in the mouse brain revisited.
Authors: Rosenblum W I
Published: June 2011

Arteriolar responses were measured on the cerebral surface of the mouse using an image splitter and TV monitor. The response to locally applied norepinephrine (NOR) was significantly more frequent for vessels greater than 30 mu I.D. than for smaller vessels. However, even the smaller vessels were frequently constricted by NOR in doses of 5 mug per milliliter. Reserpine (5 mg per kilogram) failed to alter the response to NOR at either 24 or 72 hours after reserpinization. At 48 hours the threshold dose of NOR was reduced, but the effect was slight (two-tailed, P = 0.08). Both propranolol (10(-6) M3 and phentolamine (10(-5M) blocked responses to 5 mug per milliliter of NOR, but neither agent altered resting arteriolar diameter. Isoproterenol, tyramine, and histamine had no effect. Serotonin (5HT) constricted the arterioles but did not potentiate the response to NOR. Additive or potentiated effects were not observed with NOR 5HT or histamine in any combination. These data indicate the presence of alpha-adrenergic receptors in murine cerebral surface arterioles, but do not establish a significant tonic effect of norepinephrine. The existence or role of a beta-receptor in these murine cerebral surface arterioles remains an unsettled question.
Cerebellar hemorrhage: reliability of clinical evaluation.
Authors: Rosenberg G A , Kaufman D M
Published: June 2011

Surgery without confirmatory radiological contrast studies has been advocated in patients suspected of having a cerebellar hemorrhage. To determine the reliabiligy of the clinical evaluation, records were reviewed of 33 patients in whom the diagnosis of cerebellar hemorrhage was initially suspected or subsequently confirmed. In 13 patients the correct diagnosis had been made initially by clinical evaluation, but in ten patients the correct diagnosis was not suspected at the initial evaluation. The remaining ten patients had typical backgrounds, symptoms, and signs of a spontaneous cerebellar hemorrhage, but radiological contrast studies and clinical observation indicated that other neurological lesions were responsible. Thus, utilizing solely the clinical evaluation, the diagnosis of cerebellar hemorrhage may be made only with difficulty and not with the certainty required for emergency surgery.
Long-term anticoagulant therapy for TIAs and minor strokes with minimum residuum.
Authors: Olsson J E , Müller R , Berneli S
Published: June 2011

One hundred seventy-eight patients with transient ischemic attacks (TIAs) or small strokes with slight symptoms persisting for more than 24 hours (incomplete recovery = IR) (TIA-IR) from both the carotid and the vertebrobasilar systems were treated with anticoagulants. Ten patients stopped the treatment because of severe side effects. Only one patient had a lethal cerebral infarction when the thrombotest values were above the therapeutic level; no other infarction happened during the treatment period. Moreover, the frequency of TIA decreased during the treatment, compared with descriptions of the natural course of TIA. One hundred four patients were observed for a mean of 21 months after the anticoagulant treatment ended. During the observation period, six patients had cerebral infarctions. This was a sixfold increase compared with the stroke incidence during treatment, and was almost identical with the incidence of strokes seen during the natural course of TIA. All the cerebral infarctions were in patients who had their initial TIA/TIA-IR from the carotid territory (within the same carotid artery which earlier had given symptoms). The investigation shows that long-term anticoagulant treatment is useful, especially in patients with carotid TIA/TIA-IR, and that this treatment should continue as long as the patients can manage it. In patients with vertebrobasilar symptoms of malignant character, it seems feasible to terminate the treatment after about one year. The mechanism of the anticoagulant treatment is obscure, but it does not appear to influence the progress of the atherosclerotic process.
An evaluation of hypocarbia and hypercarbia during carotid endarterectomy.
Authors: Baker W H , Rodman J A , Barnes R W , Hoyt J L
Published: June 2011

One hundred consecutive patients were randomly given hypocarbic (PaCO2 less than 25 torr) or hypercarbic (PaCO2 greater than 60 torr) general anesthesia during carotid endarterectomy to test the effect of the two regimens upon the incidence of postoperative neurological deficit. An indwelling shunt was not used. One patient died, two have permanent neurological deficits and two have temporary neurological deficits. Although hypocarbic patients had fewer neurological complications than hypercarbic patients, the difference was not statistically significant (p less than 0.13). Hypercarbia significantly increased the incidence of intraoperative arrhythmia. Also, no relationship was found between the incidence of postoperative stroke and the internal carotid back pressure or the time of carotid occlusion.
Scanning electron microscopic appraisal of a new micro T-tube.
Authors: Gregorius F K , Rand R W
Published: June 2011

A new micro T-tube, 0.6 mm in outer diameter, has been constructed. Use of this tube has allowed 1-mm common carotid artery (CCA) bypass ofr periods of time up to 22 minutes. After bypass, scanning electron microscopic observation of sutured CCA endothelium showed widespread destruction, scattered attached platelets and other formed blood elements, as well as microthrombi both at suture lines and in areas in contact with T-tubes. Despite microthrombi, 41 of 42 CCAs were patent after anastomosis. Silicone cuffs and 8-0 ties secured T-tubes inside vessels with no apparent difference in underlying endothelial destruction.
Prognosis of patients with unilateral extracranial occlusion of the internal carotid artery.
Authors: Waltimo O , Kaste M , Fogelholm R
Published: June 2011

One hundred fifty-five patients (121 men and 34 women) had an angiographically verified unilateral internal carotid artery (ICA) occlusion immediately after carotid bifurcation. The median follow-up period was 53 months. Forty-five percent of the patients were fully independent in the activities of daily living (ADL), 22% required assistance in ADL, 11% were disabled, and 22% died within the follow-up period. The mortality rate was exceptionally low compared with previous series. A life-table analysis of the material gave a 94% probability of surviving the first year, 84% the third year, and 78% the fifth year. Young age was favorable in regard to functional recovery, but it had no influence on mortality. The condition at the acute stage was the most important clinical sign in predicting the prognosis. The prognosis of mortality and functional recovery was poorer for smokers than for nonsmokers, and hypertension had no effect on prognosis. Cerebrovascular disease and coronary heart disease were found to be the cause of death with equal frequency in this study.
Pyramidal tract responses (PTR) during hypoxia and hypotension.
Authors: Sutter R , Wiederholt W C
Published: June 2011

In rats with unilateral carotid artery ligation pyramidal tract responses were studied during hypoxia and during trimethaphan-induced hypotension. Observations on EEG activity during hypoxia suggest that unilateral carotid artery ligation produces a more severe perfusion defect in lateral portions of the hemisphere. During hypoxia and during trimethaphan-induced hypotension indirect PTRs disappeared first from the hemisphere on the side of carotid artery ligation and next from the opposite hemisphere. This was followed by loss of direct PTRs in the same order. Animals could not be resuscitated once the direct PTR from the non-ligated hemisphere had disappeared. Hypotension appears to be a late contributing factor in impairing electrocerebral activity during hypoxia in this study.
Coincidental multiple asymptomatic intracranial aneurysms and symptomatic carotid stenosis.
Authors: Shoumaker R D , Avant W S , Cohen G H
Published: June 2011

A patient experiencing transient cerebral ischemic attacks (TIAs) was studied angiographically and found to have a symptomatic stenosis of the appropriate internal carotid artery (ICA) and three asymptomatic intracranial aneurysms. A therapeutic approach to this type of problem is discussed in this article.
EEG surveillance as a means of extending operability in high risk carotid endarterectomy.
Authors: Matsumoto G H , Baker J D , Watson C W , Gleucklich B , Callow A D
Published: June 2011

Some patients who have transient ischemic attacks are denied operation because severe occlusive lesions in other extra-cranial arteries may be inappropriately interpreted as constituting an unacceptable surgical risk, or because the lesion is so distal as to make its removal hazardous. Failure of endarterectomy is usually due to incomplete removal of the lesion or to thrombosis upon the frayed intima. Such lesions require excellent visualization and meticulous surgical technique -- not always possible with a shunt. Among 130 consecutive carotid endarterectomies performed under general anesthesia, EEG changes consistent with cerebral ischemia appeared in only nine (7%). These patients required a shunt. In 11 patients normal EEG tracings were obtained during endarterectomy despite contralateral carotid occlusion. None of these patients had a neurological deficit. Continuous EEG monitoring is a reliable method of detecting changes in cerebral perfusion, permits a more meticulous endarterectomy in high-lying lesions without a shunt, and extends operability in high risk patients. Angiographical findings may be an unreliable predictor concerning risk of endarterectomy.
Comparison of vascular reactivity in spinal cord and brain.
Authors: Nix W , Capra N F , Erdmann W , Halsey J H
Published: June 2011

The local tissue PO2 in the brain cortex and in the spinal cord of rats was examined with ultramicroelectrodes. In the spinal cord the PO2 was highest in white matter, intermediate in dorsal horn gray matter, and lowest in the ventral horn gray matter. In the gray matter of the cord, as well as in the brain, the PO2 at a fixed locus was found normally to oscillate. CO2 responses were more brisk in the cord than in the brain while the responses to hypoxia were similar. Therefore, it appears that the physiological regulation of blood flow in the spinal cord is qualitatively similar to that of the brain.
Paradoxical dilation of the large cerebral arteries in hypocapnia in man.
Authors: Radü E W , du Boulay G H
Published: June 2011

By grouping patients who had carotid angiograms under unusually carefully monitored conditions it has been shown that hypocapnia is associated with vasodilation at low blood pressure but not at high blood pressure. The mechanism is discussed in general terms and it is suggested that the hypocapnic vasodilation may be a response to cerebral hypoxia and may be transmitted via an intracerebral autonomic pathway. Clinical and angiographical diagnoses are given for 50 patients.
Cerebral atherosclerosis in Japanese. Part 4: relationship between lipid content and macroscopic severity of atherosclerosis.
Authors: Nakamura M , Imaizumi K , Kikuchi Y , Kanaide H
Published: June 2011

In order to evaluate chemically the macroscopic scoring methods for severity of arteriosclerosis in the cerebral arteries, concentrations of total lipids, esterified and free cholesterol and lipid phosphorus were compared to the macroscopic severity of lesions in the cerebral arteries obtained from 376 Japanese persons after unexpected death. An increase of cholesterol content was correlated significantly with an increase of Baker's score and/or Gore's atherosclerotic index. The correlation coefficient between Baker's score and total or esterified cholesterol was the highest among the tested correlations (r = 0.82, n = 376).
Cerebral atherosclerosis in Japanese. Part 5: relationship between cholesterol deposition and glycosaminoglycans.
Authors: Nakamura M , Imaizumi K , Shigemi U , Nakashima Y , Kikuchi Y
Published: June 2011

Concentrations of various lipids and glycosaminoglycans (GAG) in the intima of the grossly normal and atherosclerotic cerebral arteries were compared with those of the aorta and coronary arteries. The lowest percentage of esterified cholesterol (EC) in total cholesterol, and of chondroitin sulfate-4/6 (CS-4/6) in total glycosaminoglycans and the highest percentage of heparin sulfate (HS) in total GAG are the characteristic features of the normal intima of normal cerebral arteries when compared with those in the aorta and coronary artery. In the cerebral arterial intimas, but not in the aorta or coronary arteries, there was a significant positive correlation between contents of EC and percentage and total content of CS-4/6. Atherogenesis in cerebral arteries is discussed in comparison to that of the aorta and coronary vessels.
A prospective study of cerebrovascular disease in Japanese rural communities, Akabane and Asahi. Part 1: evaluation of risk factors in the occurrence of cerebral hemorrhage and thrombosis.
Authors: Okada H , Horibe H , Yoshiyuki O , Hayakawa N , Aoki N
Published: June 2011

An epidemiological study of cerebrovascular disease in Akabane and Asahi, Japan, was made. (These cities are located near Nagoy, Japan.) The study population included 4,737 men and women aged 40 to 79 at the time of entry into the study. There were 4,186 persons who were examined and, of these, 264 cases of cerebrovascular attacks were observed between 1964 and 1970. The incidence rate of stroke in those persons not responding to the survey was 15.9 times higher than in those persons examined according to person-year observation in Akabane. The risk factors for cerebral hemorrhage and thrombosis were evaluated by age-adjusted and sex-adjusted relative risks. The predisposing factors to cerebral hemorrhage appeared to be high blood pressure, high left R wave, ST depression, T abnormality, capillary fragility counts, previous medical history of stroke and albuminuria. For cerebral thrombosis, the predisposing factors appeared to be high blood pressure, ST depression and funduscopic sclerotic findings, and those factors assumed to be significant were glycosuria and smoking habits. Ocular funduscopic abnormality was the most prominent risk factor for cerebral thrombosis, while high blood pressure and ECG abnormalities were highly related to cerebral hemorrhage. It was suggested that those subjects with a relatively higher blood pressure may have a higher relative risk of cerebral hemorrhage than those with a lower (normal range) blood pressure. A previous or family history of stroke also appeared significantly related to cerebral hemorrhage.
Dynamic response of the intracranial system in the conscious dog to papaverine hydrochloride.
Authors: Schettini A , Furniss W W
Published: June 2011

The influence of papaverine on the intracranial system of the dog was studied by measuring the pressure-depth-time response for the intact intracranial system, i.e., for the subarachnoid and subpial compartments. This was accomplished by a measurement system which provided an accurate pressure-depth determination and a uniform rate of transducer insertion. Distinct regions of the intracranial system (subarachnoid, transitional, and subpial) were identified from inflections in the pressure response curve. The test parameter, brain relative stiffness (BRS), was obtained by determining the slope of the pressure response values within the subpial region. This parameter is a measure of the "stiffness" or elasticity of bring tissue within the test configuration. A bolus injection of papaverine (1 mg per kilogram, i.v.) caused an increase in the transitional region, a compensatory reduction in the subarachnoid space, and an increase in BRS. It is postulated that at normotensive arterial blood pressure, cerebrovascular expansion caused by papaverine resulted in increased brain tissue elasticity, i.e., an increase in the pressure-depth response for the subpial region. Possible implications for this increase are discussed. Experiments should be conducted in which local blood flow studies are coupled with measurements of brain elastic response.
Subcortical arteriosclerotic encephalopathy (Binswanger's disease). A vascular etiology of dementia.
Authors: Burger P C , Burch J G , Kunze U
Published: June 2011

A 51-yearold man with moderate intermittent hypertension had a rapidly progressive, profound dementia in the absence of significant localizing neurological signs. Postmortem examination disclosed the vascular alterations and diffuse white matter degeneration which characterize subcortical arteriosclerotic encephalopathy (SAE) or Binswanger's disease. The case underscores the need to consider vascular disease as an etiology of dementia -- even in the absence of focal neurological deficit.
Reserpine and cerebral vasospasm.
Authors: Watts C
Published: June 2011

Cerebral vasospasm was produced in the dog basilar artery by topically applied five-day-old clotted autologous blood, but not by freshly drawn blood. The spasm was reversed by methysergide, an antiserotonin agent. However, vasospasm was not produced by five-day-old clotted autologous blood from dogs pretreated with reserpine. This suggests platelet serotonin or a similar, unidentified substance as the vasospastic element in dog blood responsible for experimental vasospasm from topically applied whole blood. Other experimental data support these findings.
Effect of cerebrospinal fluid removal on cerebral blood flow and metabolism in patients with Alzheimer's disease versus recent stroke.
Authors: Meyer J S , Miyakawa Y , Ishihara N , Itoh Y , Naritomi H , Mathew N T , Welch K M , Deshmukh V D , Ericksson A D
Published: June 2011

Cerebral hemispheric blood flow (HBF) and metabolism were measured before and after withdrawal of 20 to 30 ml of cerebrospinal fluid (CSF) over a 10-minute interval in eight patients with recent cerebral infarction and in four patients with Alzheimer's disease (AD). Immediately after CSF removal HBF decreased significantly in the AD group (-14%) but showed no significant change in the stroke group (-5%). There was rapid reduction in cerebral venous O2 content and some increase in cerebral venous PCO2 appearing within 60 seconds of CSF withdrawal, interpreted as a rapid reduction of cerebral blood flow (CBF) as judged by cerebral A-VO2 differences. The reduction in CBF was confirmed by the hydrogen clearance method. Reduction of CBF in response to lowering CSF pressure is presumably of neurogenic origin since it was rapid and occurred without changes in PaCO2 or MABP. Furthermore, measurement of HBF demonstrated that cerebral metabolism constant after CSF removal. It is postulated that in AD, reduction of HBF following CSF withdrawal is mediated by a disordered neurogenic veno-arterial vasoconstriction reflex which is stimulated by rapid reduction in CSF pressure (CSFP). In patients with stroke, when cerebral perfusion pressure is increased by lowering CSFP, CBF is maintained constant most likely by a physiological cerebral veno-arterial vasoconstrictive reflex. Apparently, this vasocontrictive reflex becomes excessive in Alzheimer's disease, possibly due to cerebral neurogenic imbalance.
Failure of prolonged hypocapnia, hypothermia, or hypertension to favorably alter acute stroke in primates.
Authors: Michenfelder J D , Milde J H
Published: June 2011

The effects of induced hypocapnia, hypothermia, and hypertension were surveyed in a primate model of acute stroke during and following a 48-hour period of intensive care. The results were compared to a group of nine control animals previously studied. Hypocapnia (PaCO2=25 torr) was examined in five animals and did not appear to alter the expected mortality, degree of neurological deficit, or frequency of infarction. There was, however, a suggestion that the size of infarction may be reduced. Hypothermia (29 degrees C) in five animals had a detrimental effect in that no animals survived following the intensive care period and all had infarction with massive edema. We speculate that hypothermia caused a sufficient increase in blood viscosity as to compromise collateral flow, thereby accounting for this detrimental effect. Induced hypertension (to 20% above control levels) was abandoned after three animals because of severe systemic effects (cardiac failure and pulmonary edema) resulting in death during the period of intensive care.
Sympathetic regulation of cephalic blood flow.
Authors: Meyer M W , Smith K A , Klassen A C
Published: June 2011

Blood flow to bilateral tissues (cranial and extracranial) was studied by means of the particle distribution method in two groups of anesthetized dogs (five using 25-mu radioactive microspheres, six using 15-mu microspheres) and five anesthetized stumptail Macaques monkeys (8-mj spheres) during unilateral sympathetic stimulation. The stimulatory parameters were adjusted to produce maximum pupillary dilatation. In the five dogs hemispheric and regional cerebral blood flow decreased but not significantly. Flow to the extracranial tissues decreased 82%. Hemispheric brain blood flow averaged 0.70 ml/min/gm for Paco2 of 40 mm Hg. In the six dogs sympathetic stimulation did not significantly decrease cerebral blood flow but decreased flow to extracranial tissues (72.3%). At an average Paco2 of 33.2 mm Hg, hemispheric blood flow to the unstimulated side averaged 0.51 ml/min/gm. In the five monkeys findings were essentially the same as those observed in the dogs. The hemispheric blood flow averaged 0.36 ml/min/gm on the nonstimulated side for an average Paco2 of 36.6 mm Hg. Under the conditions studied, electrical stimulation of the cervical sympathetic nerves does not appear to modify regional or total brain blood flow in dogs and Macaques monkeys. The vascular response in oral and other extracranial tissues is very dramatic, however.
Diurnal variation in occurrence of strokes.
Authors: Marshall J
Published: June 2011

The time of onset of a completed stroke was recorded in 707 patients. Of the 554 cerebral infarctions 40% occurred between midnight and 6 a.m. Onset at night was, if anything, less common among the 153 cases of cerebral hemorrhage.
Effects of high static pressures on human cerebral arteries in vitro.
Authors: Cope D A , Roach M R
Published: June 2011

Static elastic properties were obtained from pressure, volume, and length measurements of 34 isolated human cerebral arteries from 23 circles of Willis of patients aged 23-76 years. No significant difference in initial or final elastance was observed with age or branch in the circle of Willis. Twenty-four of the arteries from 18 circles of Willis were then subjected to transmural pressures of 200-300 mm Hg for periods of less than or equal to 5 minutes and the elastic properties restudied. In general, this had little effect on the arteries except for a significant increase in the initial radius for the less than or equal to 40 year age group. In the less than or equal to 40 year group, female arteries tended to show a greater increase in initial elastance than the males. Histological studies to look for elastin fragmentation in the intima were inconclusive.
Direct evidence for absence of beta-adrenergic receptors in rat cerebral vessels histochemical study with a fluorescent beta-blocker.
Authors: Melamed E , Atlas D , Lahav M
Published: June 2011

A fluorescent marker for beta-adrenergic receptor sites, 9-amino-acridin propranolol (9-AAP), was administered intravenously to rats. In contrast to other tissues which are known to contain beta-adrenergic receptors, 9-AAP fluorescence was not observed in the walls of the pial as well as parenchymal cerebral vessels. These negative findings strongly suggest that in the rat, beta-adrenergic receptors are not present in the cerebral vasculature. The role of the alpha-adrenergic receptors needs more study.
Variations in mean cerebral blood flow under anesthesia at rest and during cortical activation.
Authors: Palmer N I , Thomas D J , MacGillivray B B , Du Boulay G H , Marshall J , Russell R R , Symon L
Published: June 2011

More than one cerebral blood flow (CBF) measurement was performed on the same occasion in three groups of patients using the intracarotid 133Xenon technique. In the anesthetized group there was a highly significant reduction in CBF (mean = 24.3%) from the first to the second measurement. In those at rest under local anesthesia there was also a significant fall (mean 9.8%). The third group, who were stimulated during the second estimation, showed no change. A second CBF determination some time after beginning a study is recommended, especially in pharmacological studies, to provide a more reliable resting control, rather than the first value which represents flow in an "activated" brain which has not yet adapted fully to its new environment.
Cerebrovascular response to infused 5-hydroxytryptamine in the baboon. Part 2. 5 Hydroxytryptamine infusion in estrogen and progesterone treated animals.
Authors: Mendelow A D , Eidelman B H , McCalden T A , Rosendorff C
Published: June 2011

The effect of intracarotid infusion of 5-hydroxytryptamine (5-HT) on cerebral blood flow was studied in five female baboons 7 days after intramuscular injection of slow release estrogen and progesterone. The control values for total cerebral blood flow, grey matter flow, and white matter flow were 38.9, 57.5, and 11.0 ml/min/100 gm of tissue respectively. There was a statistically significant decrease in total, grey and white matter blood flow during infusion of 5-HT at dosages ranging from 0.5 to 10.0 microng/kg/min. The study indicates that in female baboons pretreated with estrogen and progesterone, intracarotid infusion of 5-HT produces a dose dependent decrease in cerebral blood flow, which did not occur in control animals.
Effect of cerebrospinal fluid removal on cerebral blood flow and metabolism in the baboon: influence of tyrosine infusion and cerebral embolism on cerebrospinal fluid pressure autoregulation.
Authors: Miyakawa Y , Meyer J S , Ishihara N , Naritomi H , Nakai K , Hsu M C , Deshmukh V D
Published: June 2011

Cerebral blood flow (CBF) and metabolism were measured before and after withdrawal of 5 to 6 ml of cerebrospinal fluid (CSF) in 17 baboons. The measurements were made before and after infusion of tyrosine, the precursor amino acid of the putative neurotransmitters, dopamine and norepinephrine, in the brain. The same observations were made in another experimental group, i.e., before and after acute cerebral multiembolization induced by microfil emboli. In the steady state CBF was unaltered following reduction of intracranial pressure by removal of CSF. After infusion of tyrosine, CBF was decreased, and cerebrovascular resistance increased significantly on removal of CSF. Cerebral embolization did not influence changes in CBF at reduced intracranial pressure. It appears that the cerebral resistance vessels constrict following reduction of intracranial pressure by removal of CSF and that cerebrospinal fluid pressure-CBF autoregulatory mechanisms are resistant to cerebral ischemia induced by middle cerebral artery embolization.
Experimental subarachnoid hemorrhage from a middle cerebral artery. Neurologic deficits, intracranial pressures, blood pressures, and pulse rates.
Authors: Hayakawa T , Waltz A G
Published: June 2011

Devices to produce experimental subarachnoid hemorrhage (SAH) can be implanted in animals. After SAH is produced by the puncture of a middle cerebral artery (MCA) in awake cats, neurologic deficits develop that are not as severe as those caused by MCA occlusion. Biphasic increases of epidural pressure occur and are related to the extent and distribution of the hemorrhage. Ischemic changes are more severe if the flow of blood through the MCA is interrupted.
Automatic end-tidal gas sampling system for non-invasive rCBF measurements.
Authors: Shapiro H M , Inacker J E , Obrist W D
Published: June 2011

Non-invasive measurements of regional cerebral blood flow (133Xe inhalation or IV injection) require knowledge of the arterial 133Xe concentrations, which is usually estimated from the end-tidal expiration. An automated sampling system is described for measurement of end-tidal 133Xe concentration that can be used in both spontaneously breathing and mechanically ventilated patients. A comparison is made between the automatic sampling system and manual measurements performed on a continuous gas sample.
Cardiac arrhythmias in experimental subarachnoid hemorrhage.
Authors: Estanol B V , Loyo M V , Mateos J H , Foyo E , Cornejo A , Guevara J
Published: June 2011

Experimental subarachnoid hemorrhage (SAH) in dogs was produced by introducing blood into the subarachnoid space through a catheter connected to an artery of the animal. The intact animals and those with preserved vagi and heart sympathetic innervation, developed arrhythmias with short latencies which correlated with the sudden increase in the intracranial pressure. The animals with sections of both vagi and heart sympathetic innervation, but with an intact spinal cord, developed arrhythmias that were delayed and did not correlate with the changes in intracranial pressure. These arrhythmias were preceded by changes in the QT interval, T wave and ST segment. It was concluded that the arrhythmias could be produced either by direct autonomic discharges to the heart or by increased circulating and tissue catecholamines. The clinical implications of these findings are discussed.
Global brain ischemia: a reproducible monkey model.
Authors: Nemoto E M , Bleyaert A L , Stezoski S W , Moossy J , Rao G R , Safar P
Published: June 2011

We developed a monkey model of 16 minutes global brain ischemia (GBI) resulting in reproducible, severe, permanent functional neurologic deficit with long term (7 days) postischemic (PI) survival made possible by standardized intensive care with 24 hour coverage by trained personnel. Quantitated neurologic deficit (ND) and brain histopathological examinations were developed. Fifteen minutes GBI resulted in rapid recovery within12--24 hours PI without residual neurologic sequelae. Twenty minutes GBI caused severe neurologic deficit and within 4 days PI, a delayed Cushing response eventually leading to cardiac arrest. Sixteen minutes GBI resulted in severe neurologic deficit (monkeys unable to sit, stand, walk, or feed themselves), but with long term survival. Brain histopathological analyses revealed a combination of cortical and brainstem lesions. Severest changes were observed in the occipital (calcarine) cortex with less severe damage in the frontal and temporal regions. Oculomotor nuclei and medial longitudinal fasciculus in the midbrain were regularly affected. With this model we can test the efficacy of promising therapies in terms of clinically relevant variables.
Cervical manipulation and stroke.
Authors: Easton J D , Sherman D G
Published: June 2011

Three patients are described who experienced vertebro-basilar distribution infarctions associated with neck manipulation. Two of the manipulations were chiropractic. Twenty-two previously reported cases are reviewed. Evidence favoring the use of anticoagulation in these patients is discussed along with the relative risk of such therapy.