ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Transient ischemic attacks are the most important warning symptoms of impending stroke. They occur in up to one-half of all patients who develop stroke but, unfortunately, less than half of the patients who have them seek help from their physicians before stroke occurs. Physicians should regularly question patients about the possibility of such symptoms and patients with them should seek prompt help. When transient ischemic attack is diagnosed, patients should be evaluated for elevated blood pressure, hyperlipidemia, cardiac dysrhythmia, cardiac disease, anemia, polycythemia and thrombocytosis. When these conditions are found they should be treated. Patients with carotid system TIAs should be evaluated clinically and radiologically for evidence of vascular disease. The neck should be auscultated for bruit and absent pulses and the peripheral vessels palpated. Patients with carotid system TIAs should have angiography of all 4 cerebral vessels and the angiogram should be evaluated for the presence and number of arterial stenoses and the presence of ulcerated plaques. When patients with carotid system TIAs are found to have localized extracranial atherosclerotic obstruction or ulcerated plaques in a vessel appropriate to the side of their symptoms of cerebral ischemia, they should be considered for prompt surgical correction of the lesion. For patients with carotid system TIAs, who have multiple sites of extracranial vascular disease, medical treatment is advisable with either anticoagulants or platelet antiaggregating agents. In view of the recently reported favorable results using aspirin in the prevention of TIA and stroke, this agent may be preferable to anticoagulants in instances where hypertension, patient compliance and laboratory facilities are a problem.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Patients (125) who had carotid transient ischemic attacks (TIAs) and one or more accessible carotid lesions visualized angiographically had reconstructive operations of the carotid artery and werethen randomly assigned to aspirin or placebo treatment. They were followed to determine the incidence of subsequent TIAs, death, cerebral infarction, or retinal infarction. Life table analysis (for 24 months follow up) that eliminated deathswhich were not stroke-related revealed a significant difference in favor of aspirin. Because of the small number of patients and the short period of follow up, these results should be interpreted only as consistent with those reported in the initial publication but not conclusive of an aspirin effect in preventing cerebral infarction.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Little attention has been given to assessing risk factors for cerebrovascular disease (CBVD) and less has been given to relatinglong term changes in blood pressure (BP) to CBVD occurrence. In the Manitoba Study811 a cohort of 3,983 North American men (predominantly between 25-34 years of age at entry in 1948), measured 5 times during the 26 year observation period from 1948 to 1974, was related tothe incidence of CBVD. Used were measurements of age, systolic (SBP) and diastolic (DBP) blood pressure and Body Mass Index-weight/height2 determined at entry and at examination closest to July 1, 1954, 1959, 1964 and 1969. Change was calculated as the difference in these variables between examinations. In order to adjust for age and BP as CBVD risk factors, as well as for the effect both may have on the rate of BP change, the data were analyzed using multivariate as well as univariate methods. After adjusting for age and SBP, change in SBP was significantly associated with subsequent CBVD, primarily in men middle aged or older. When considering SBP after entry, changes from a measurement 5 yearsearlier were more important than SBP changes over longer intervals. Thus, in evaluating SBP as a risk factor for CBVD, the rate of change in SBP is also an important factor in the identification of the stroke prone individual.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Changes in cerebral cortex concentrations of high-energy phosphates, glycolytic metabolites, citric acid cycle intermediates, associated amino acids, and ammonia, were studied after 5, 15 and 30 min of incomplete ischemia in rats anesthetized with 70% N2O or 150 mg-kg ' of phenobarbital. Previous results have shown that with this type of ischemia (bilateral carotid artery occlusion combined with reduction in blood pressure to 50 mm Hg) cortical blood flow is reduced to below 10% of nitrous oxide control values, whether animals areanesthetized with 70% N2O or 150 mg-kg"1 of phenobarbital. In animals under 70% N2O, changes in tissue concentrations of phosphocreatine, ATP, ADP and AMP were similar to those previously obtained in complete ischemia. However, some glucose remained in the tissue, and the lactate concentrations gradually rose to reach excessive values. Changes occurring in glycolytic and citric acid cycle intermediates were similar to those seen in complete ischemia but, after 30min, there was some reduction in the pool size of amino acids. In those animals given phenobarbital and which lost all EEG activityduring ischemia, changes in cerebral metabolites were virtually identical to those observed in nitrous oxide-anesthetized animals. However, some animals exposed to 5 or 15 min of ischemia had some remaining EEG activity. In these, cerebral energy state was significantly less deranged, and levels of glycogen, glucose and pyruvate were higher.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Recovery of cerebral energy metabolism, following 15 or 30 min of pronounced, incomplete ischemia, was studied after 90 min of recirculation in rats that were either anesthetized with 70% N2O or 150 mg kg'1 of phenobarbital. In all animals arterial blood pressure, Poa and Pco, were close to normal during recirculation. In nitrous oxide-anesthetized animals kept ischemic for 30 min, but not in those given phenobarbital, a gradual rise in intracranial cerebrospinal fluid (CSF) pressure (to about 20-25 mm Hg) occurred during the last 20-30 min of recirculation. Following 15 min of ischemia, all phenobarbital-anesthetized animals, and 20 out of 24 animals anesthetized with 70% N2O, showed extensive restitution of cerebral energy metabolism, including normalization of phosphocreatine concentration, return of adenylate energy charge to about 99% of control, and disappearance of virtually all of thelactate accumulated during the ischemia. These changes, and the pattern of changes in glycolytic and citric acid cycle intermediates, indicated that a near-normal mitochondrial metabolism returned. Following 30 min of ischemia in phenobarbital-anesthetized animals, a similar degree of recovery was observed. However, no animal maintained on 70% N, O showed such signs of metabolic recovery. The present results, and those previously reported from this laboratory, demonstrate that complete ischemia is followed by a significantly better recovery of cerebral energy metabolism than is a corresponding period of incomplete ischemia. Furthermore, the results demonstrate that phenobarbital protects under conditions of incomplete ischemia even when itdoes not prevent energy depletion from rapidly occurring during ischemia.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Using the "double indicator" technique the ability of 3H-isoproterenol and "C-propranolol to cross the blood-brain barrier was studied in man. In 3 subjects extraction of isoproterenol was 3.8% ina single passage and the PS product was 2.0 ml/lOOg/min. In 4 patients extraction of propranolol was 63% and PS was 46.7 ml/100/min. Regional cerebral blood flow (rCBF) was studied in man with the 133Xe-intraarterial injection method. Intracarotid isoproterenol (3 /xg/min., 6 patients) caused a significant reduction in rCBF, but after correction for a concomitant decrease in arterial Pco2 the alteration was no longer significant (59.8 - 51.7/57.4 ml/100g/min.). Intracarotid propranolol (0.15 mg/kg, 11 patients) caused no significant change in rCBF, but after correction for arterial Pco2 change the alteration although only 4% was just significant,/? < 0.05. (56.3–55.8/54.1ml/lOOg/min). After propranolol the rCBF changes caused by alterations in the arterial Pco2 were normal and the focal flow increase during hand work could not be changed by simultaneous intracarotid propranolol.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Effects of angiotensin-induced acute hypertension on cerebral metabolism were studied in normotensive (NTR), spontaneously hypertensive (SHR) and experimental renovascular hypertensive rats (RHR). Lactate, pyruvate and adenosine triphosphate (ATP) concentrations inthe brain frozen in situ at 18-20 min after angiotensin infusion, which raised mean arterial pressure (MAP) by 28-62% of control, were determined by enzymatic methods. Supratentorial lactate was significantly increased to 135% of control in RHR, its increase being correlated with the degree of hypertension, whereas it remained unchanged in NTR or SHR. Furthermore, RHR showed a tendency toward increase in lactate/pyruvate ratio with a decrease in ATP despite no change of arterial acid-base balance measured simultaneously before and after acute induced hypertension.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Acute alterations in plasma bicarbonate concentration have minimal effects on intracerebral pH and cerebral blood flow, perhaps due to blood-brain barrier mechanisms. To test this hypothesis, the consequences of an acute rise in the plasma bicarbonate concentration were studied in anesthetized rats previously subjected to an acute pressure pulse in the carotid system with unilateral damage to the blood-brain barrier. In rats subjected to a "heavy" hypertensive insult, the hemisphere on the side of the lesion showed a lactic acidosis, edema, and a depression of cerebral blood flow. An increase in the plasma bicarbonate concentration of 15-20 mEq/l during 35 minutes provoked a marked rise in the total CO2 content of this hemisphere, and a further increase in the lactate concentration, but did not alter the brain edema nor affect further the already very low cerebral blood flow. An increase in the lactate concentration and a decrease of cerebral blood flow in the "reference" hemisphere indicated that the lesion was not completely unilateral. In rats subjected to a "moderate" hypertensive insult the changes were less pronounced and statistically not significant for all the parameters. The results illustrate the importance of an intact blood-brain barrier for the maintenance of intracerebral pH in the face of acute alterations in plasma [HCOj]. The impaired cerebral blood flow after an acute hypertensive insult did not appear to be influenced by the intracerebral [HCO;].

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Ophthalmic artery blood flow in 5 patients with internal carotid artery occlusion of sudden onset was monitored by an ultrasonic Doppler flowmeter to investigate the possible relationship to spontaneous recanalization of the occluded artery. The occluded internal carotid arteries of 2 patients were confirmed angiographically to recanalize and the reversed flow of their ophthalmic arteries changed to physiological flow after the recanalization. The ophthalmic artery blood flow remained reversed in 2 patients whose occluded internalcarotid arteries did not recanalize on the follow up angiograms. In the other patient, whose ophthalmic artery blood flow was not detected by the ultrasonic Doppler flowmeter in the acute stage, physiological flow through the ophthalmic artery was detected later. The occluded internal carotid artery did not recanalize and this physiological ophthalmic artery blood flow was filled through the circle of Willis.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID