ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The concept that reflex control of cerebral vessels is unimportant has been challenged by recent studies which suggest that carotid baroreceptors have an important role in regulation of cerebral blood flow (CBF). In this study we have tested the hypothesis that arterial baroreceptors contribute to regulation of total or regional CBF. CBF was measured in anesthetized dogs with 15 % microspheres. Stimulation of carotid baroreceptors, by raising carotid sinus pressure, did not alter or redistribute cerebral flow. Responses to baroreceptor stimulation were intact, as manifested by vasodilation in skeletal muscle. CBF decreased during systemic hypocapnia and increased during hypercapnia, which indicates that failure of cerebral flow to change during baroreceptor stimulation was not due to unresponsiveness of cerebral vessels. During hypercapnia, baroreceptor stimulation also failed to alter CBF. In other studies CBF was measured during increases in systemic arterial pressure, before and after denervation of arterial baroreceptors. Increases in arterial pressure did not increase CBF either before or after denervation of baroreceptors. We conclude that baroreceptor stimulation does not alter total or regional CBF and that baroreceptors do not regulate cerebral flow during systemic hypertension.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

A model for production of spasm of the anterior cerebral artery in primates is presented. The model consists of injection of 0.35 cc of fresh blood into the chiasmatic cistern through theoptic canal after orbital exenteration. Clinical and angiographical follow-up is possible. The clinical appraisal of acute and chronic changes can be accomplished in the awake animal.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

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.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Of 135 patients who were resuscitated after cardiac arrest and who died from one day to several weeks later with morphological signs of systemic cerebral anoxia, there were seven patients (5.2%) with brain infarcts probably caused by hypotensive episodes during or after the resuscitation. There was almost no increase in the frequency of recent brain infarcts with an increasing degree of cerebral atherosclerosis (P > 0.90). In contrast, the distribution of ten old brain infarcts in the same material showed a significant correlation to the degree of cerebral atherosclerosis (P < 0.05). The findings suggest that the combination of cerebral atherosclerotic stenoses and hypotensive episodes is not a major cause of brain infarcts in elderly people. It is suggested that the risk of precipitating brain infarcts by lowering BP in hypertensive patients is not much greater in atherosclerotic than in nonatherosclerotic subjects.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Cardiac output (CO), arterial blood pressure (ABP), heart rate (HR), blood gases and blood flow (BF) to the brain, heart, kidney and skeletal muscles and other cephalic tissues in five dogs were studied before and at 30 minutes of betahistine infusion (0.12 to 0.2 mg per minute per kilogram). The particle distribution method using radioactive labeledl41Ce (15 %) and85Sr (15 %) microspheres was utilized to quantitate and assess BF and CO. In the five dogs, the increase in CO averaged 20.8%, ABP remained constant, and HR increased in all but one exception where it decreased slightly concomitant with a decrease in Paco2. Brain BF increased (+ 29.6%) in the dogs whose Paco2remained constant. The BF increased to the heart (25.4%) and skeletal muscle (80%), while BF to the kidney and other tissues did not change. The change in HR appears to account for the change in CO. The dilating effect of betahistine on blood vessels, in the skeletal muscle, brain and heart could reduce peripheral resistance and decrease ABP. Thus, the increase in HR may be mediated through baroreceptor mechanisms rather than by a direct effect of betahistine. In addition, a decrease in Paco2is more effective for decreasing cerebral BF than betahistine is for increasing blood flow.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

In order to compare the difference in the vulnerability of macromolecular syntheses, protein, RNA, and lipid syntheses were studied with ischemic brain tissue three hours following unilateral carotid ligation in gerbils. Precursor incorporation was measured in various subcellular fractions following in vitro incorporation with brain slices. There was marked inhibition of protein synthesis, but RNA and phospholipid syntheses showed little or no change. On the basis of available information on rapid deterioration of polysomal system for polypeptide synthesis, a hypothesis was proposed that messenger ribonucleic acid (RNA) at the polysomal level is promptly affected in this pathophysiologic condition.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

Cardiac dysrhythmia may be responsible for signs of cerebrovascular insufficiency in some patients. Ten patients with cerebrovascular insufficiency were monitored for up to 24 hours with the Holter EKG monitor. Eight of the patients had transient ischemic attacks and two had mild deficits from a completed stroke. Eight of the ten patients had associated abnormal cerebral angiography, the most frequent finding being carotid stenosis. Holter EKG monitoring in these ten patients showed no abnormalities in four patients. The remaining six had a variety of cardiac dysrhythmias. Although there were a variety of cardiac, cerebrovascular, and neurological abnormalities in these ten patients, six of these patients had a disturbance in cardiac rhythm or conduction which could have been directly associated with or suggest an etiology for the patient's neurological event.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

The number of adrenergic nerves was quantified, on xboth cerebral and femoral blood vessels. No difference was found between the two vascular beds. The data failed to establish a "richer" innervation of cerebral vessels. This is in agreement with my previous, extensive, subjective and unpublished impression. Consequently, the suggestion of others, which ascribes certain features of cerebrovascular behavior to an unusually rich vascular innervation, remains unproved.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID

摘要:

A directional Doppler ultrasound cerebrovascular examination was compared with angiographical findings of 152 internal carotid arteries. The Doppler examination was abnormal in 36 of 38 (95%) arteries with occlusion or stenosis greater than 75%. Of 63 arteries with lesser degrees of stenosis, the Doppler examination identified only four. There were no false-positive Doppler examinations. If the decision to perform angiography had been predicated exclusively on the presence of abnormal Doppler findings, 61 of 101 (60%) carotid lesions of potential clinical significance would have been overlooked. While the Doppler ultrasound cerebrovascular examination is the most useful noninvasive technique available for the evaluation of certain specific categories of patients with cerebrovascular disease, the technique is based on hemodynamic alterations of pressure and flow, and cannot be expected to identify the relatively large number of non-hemodynamically significant carotid lesions that are still clinically significant as sources of emboli. This paper illustrates that in the routine evaluation of patients with symptomatic cerebrovascular disease, the Doppler examination should not play a part in the decision to proceed with angiography.

ISSN:0039-2499    

出版商:OVID    

年代:1976

数据来源: OVID