摘要:

Non-invasive vascular testing has proven to be an effective means of identifying patients with significant extracranial carotid artery disease. Such tests can yield valuable physiologic data in patients with TIAs and can identify patients with soft signs who may have significant carotid artery disease and who may be candidates for angiography. It may be an effective means of reducing the number ofnegativecarotid angiograms.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We find that the media and adrentitia of adult human cerebral arteries contain elastic fibers forming a dense, coherent network, similar to that found in muscular arteries of the same size in other organs. The external elastic layer in the adult human is masked for the currently employed staining methods. By treatment with 90% formic acid before fixation, the original staining character of elastic tissue can be restored. The light microscopic and scanning electron microscopic features of this network of elastic fibers are presented.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Using the dog, which has been believed unsuitable for research on brain infarction because of an extensive collateral cerebral circulation, we hare succeeded in producing at will ischemlc foci, as determined from post-occlusion carbon perfusion, in the thalamus, cerebral mantle or entire cerebral hemisphere. This has been achieved by occlusion of various combinations of cerebral vessels at the base of the brain. A unilateral temporal approach has been used in identifying and occluding all of die bilateral trunk arteries. The following models of cerebral infarction have been made: 1) unilateral or bilateral complete cerebral hemisphere infarction, 2)unilateral or bilateral cerebral mantle infarction, 3) unilateral or bilateral thalamic infarction, 4) unilateral hemispheric and contralateral cerebral mantle infarction, 5) unilateral cerebral mantle and contralateral thalamic infarction, and 6) unilateral complete cerebral hemisphere and contralateral cerebral mantie infarction. These models of infarction hi the dog can be produced with a high degree of success, and the amount of infarction can be controlled by the duration of vessel occlusion. The pathophyslology of brain Infarction and brain edema following recirculation can be bemodynamically, electroencephalographically and biochemically studied using these models of cerebral infarction.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Changes of regional cerebral blood flow from rest to mental activation by a visually presented spatial reasoning test were measured during normo- and bypercapnia in 10 healthy subjects. Hypercapnia, elicited by inhalation of 6% CO2, resulted in similar flow increases in all 32 cortical regions measured. Increases of flow during testing were seen in post-central regions of the brain whether the resting level was augmented by hypercapnia or not. The results show that an elevated local functional level in the cortex causes an automatic local vasodilatory response which is totally independent of the basal level of perfusion and availability of metabolic substrates.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Diffuse cerebral ischemia was created in pentobarbital-anesthetized cats by basllar and bilateral carotid artery occlusions and hypotension. Local cerebral blood flow (1CBF) was assessed autoradiographically with14C-antipyrine, and local cerebral glucose utilization with14C-2-deoxyglucose. In animals without glucose pretreatment, 15 min of ischemia led to a homogeneous reduction of post-ischemic cerebral perfusion to 31% of control; ischemia of 30 min produced post-ischemic perfusion heterogeneities in the cerebral cortex and deep gray structures. In animals pretreated with dextrose, 1.5 gm/kg intrarenously, heterogeneous cerebral perfusion was observed following only 15 min of ischemia, and a severe global impairment of cerebral reperfusion occurred after the 30 min insult. Deoxyglucose autoradiograms in the latter animals were remarkable for a complete suppression of tracer uptake in the cerebral cortex and a paradoxically increased tracer concentration in the cerebral white matter. Mean plasma glucose in the treated animals exceeded 1000 mg/100 ml. Large glucose loads prior to ischemia dramatically Impair post-ischemic cerebral perfusion.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Glucose was Infused intravenously into cats prior to cerebral ischemia. Brain concentrations of glucose, measured in 7 regions, were elevated 2.5-fold compared to those of non-infused animals. Ischemia of 15 or 30 minutes duration caused a greater accumulation of lactic add in the brain of glucose-infused animals. Post-iscbemic restitution of cerebral ATP, phospbocreatine, and lactate during 90 minutes of reclrculation was severely impaired in the brain of animals pretreated with glucose compared to untreated animals. Thus, excess lactic addosis may be a major factor interfering with metabolic restitution following cerebral ischemia.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Purified human and borine thrombin produced comparable tonic contractions in isolated canine basilar arteries. The magnitude of the contractions was closely related to the number of thrombin Units studied rather than to the amount of protein added to the isolation bath. Thrombin had a much slower onset of action, but was more potent in generating sustained contractions than either serotonin or prostagiandin F207Moreover, in contrast to serotonin and prostagiandin F2α*, the contractions caused by thrombin were not terminated by equivalent washing. The thrombin-induced contractions were significantly inhibited by prostacyclin, medofenamic acid, pbenoxybenzamine and glycerol. Prostacydin was the most potent of these inhibitors. The results suggest that thrombin in a “free” form may cause rasoconstriction, in addition to platelet aggregation, in hemostasls and could contribute to the genesis of cerebral rasospasm associated with subarachnoid hemorrhage.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The diameters of pial vessels in the cat were measured through a closed cranial window after i.v. injection of dihydralazine (250 μg or 1 mg·kg−1). The intracranial pressure was recorded from a needle in the cisterna magna. In 7 cats given 1 mg·kg−1dihydralazine, arterial vessels with a resting diameter of 72 ± 24 nm (SD) dilated by 58 ± 21 % (p< 0.01), with no significant change seen in the reins. The intracranial pressure increased by 95 ± 30 %. The maximum increase in intracranlal pressure and arterial diameter was observed before the blood pressure had reached its lowest level. The dilatation far exceeded the autoregulatory dilatation observed at corresponding pressure reductions induced by bleeding. It is concluded that dihydralazine dilates pial arterial vessels.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The effects of diazoxide on cerebral blood flow were evaluated in unanesthetized goats under control conditions and after selective blockade of adrenergic or cholinergic receptors in cerebral vessels. Injections of diazoxide (1–27 mg) into the internal maxillary artery produced dose-dependent increases in cerebral blood flow1an increase of 90% occurring with the highest dose. Administration of pnentolamine, propranolol, or atropine into the internal maxillary artery did not modify the cerebrovascular response to diazoxide. In reserpine-treated animals the cerebral effects of diazoxide were also unchanged. Intravenous Injections of diazoxide (150–400 mg) produced sustained hypotension and tachycardia whereas cerebral blood flow was maintained within normal values or increased slightly. The normal cerebral vasoconstriction obtained with injections of norepiUephrine directly into the Internal maxillary artery was unaffected during the diazoxide induced-hypotension. These findings snow that diazoxide exerts a powerful vasodllatory effect on cerebral vessels through mechanisms other than blockade of alpha-adrenergic receptors or inhibition of adrenergic activity. The results also indicate that activation of beta-adrenergic or atropine-sensitive vascular receptors in the cerebral response to diazoxide is negligible.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

In mice breathing 5 percent oxygen, pretreatment with the optimal dose of 200 mg/kg of phenytoin increased survival time 123 percent This increase was somewhat less than that observed with certain barbiturates using the same model but significantly greater than that obsened with diazepam which is more effective than phenytoin in suppressing hypoxemlc convulsions in this model. In dogs maintained at an expired halotfaane concentration of either 0.87 percent or < 0.1 percent, phenytoin tended to decrease cerebral blood flow and had no effect on the cerebral metabolic rate for oxygen at 3 different doses. Assuming a similar effect in mice, the cerebral protection during hypoxemia observed with phenytoin cannot be explained by a reduction in metabolic rate, an increase in oxygen delivery, or by an anticonvulsant effect per se. In additional dog studies, pretreatment with phenytoin decreased the rate of potassium accumulation in cisteraal cerebrospinai fluid following 20 minutes of anoxia. We speculate that pbenytoin protection may be linked to this effect.

ISSN:0039-2499    

出版商:OVID    

年代:1980

数据来源: OVID