摘要:

Initial clinical results are reported from a new real time, 2-dimensional ultrasound scanner modified for adult cephalic applications. An optimized transducer design and the use of the dynamically focused phased array imaging system have resulted in ultrasound tomograms of the brain which are significant improvements over previous attempts. Horizontal and coronal images of the ventricles, the corpus callosum and other midline structures are routinely displayed in a 45° sector format. In addition, pulsating cerebral arteries are displayed in real time. Quantitative information can be obtained concerning cerebral vascular patency by using the selectable M-mode feature of this system. The results indicate that real time ultrasound tomography has potential for clinical application.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Enhancement of the brain substance for CT evaluation using inhaled Xenon is confirmed. This technique was applied to the study of the normal and the embolized adolescent baboon. Healthy cerebral tissue enhances symmetrically, while abnormal areas show significantly diminished enhancement. At maximal enhancement, an indication of gross comparative cerebral perfusion is obtained. By obtaining serial CT scans over a 10 minute time interval, the clearance rate of Xenon (cerebral blood flow) may be evaluated. Xenon-enhanced CT enables a visual and numerical analysis of both brain morphology and physiology.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

In the absence of universally accepted criteria for the medical treatment of stroke, we made a rigorously randomized comparative study of different treatments in 300 patients. One group of patients received only a general supportive treatment designed to ensure adequate supplies of water, electrolytes and calories, plus whatever was needed to prevent infection and correct extant associated pathology. Three other groups of patients were treated in the same way but were also given, respectively, one of the following medications: Hydergine (Sandoz) (a mixture of three ergot alkaloids), dexamethasone, and mannitol. No statistically significant difference emerged among any of the treatment groups and the reference group in terms of objective therapeutic results. The authors concluded that, at least with the dosage used in this study, none of the treatments proved more useful than conventional supportive therapy in the first 10 days after a stroke.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Uridine 5-triphosphate (UTP) induced long-lasting contractions of isolated human brain arteries; contractions without decrement were observed for periods of up to 20-24 hours at which time the tissues were relaxed in a dose-dependent manner by theophylline. In some vessels, rhythmic oscillations accompanied the prolonged elevation in tension. In canine middle cerebral arteries, UTP produced dose-related contractions within the dose range of 1.7 × 10−6to 1.7 × 10−4M; these responses were unaffected by methysergide 2.8 × 10−7M, phenoxybenzamine 2.9 × 10−5M or indomethacin 9.8 × 10−5M, suggesting that the UTP mechanism of action is probably independent of tryptaminergic or alpha adrenergic receptor activation, or of prostaglandin biosynthesis. The ability of UTP to produce prolonged contraction of cerebral vessels, thus, provides an in vitro preparation in which it is possible to study some of the basic mechanisms that are associated with cerebral vasospasm.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Fifty patients with occlusive cerebrovascular disease (ischemic thrombotic cerebrovascular disease - ITCBVD) were studied for clinical features, angiographic findings, serum lipids, platelet functions and fibrinolytic activity. Angiograms were abnormal in 24 of 36 cases. Two-thirds of these had an abnormality of the internal carotid artery in the neck; one-third had occlusion of the middle and/or anterior cerebral arteries. A statistically significant rise of serum triglycerides, pre-beta lipoproteins, platelet adhesiveness and aggregation, and a decrease in fibrinolytic activity were noticed in these patients as compared to age and sex matched controls. The correlation coefficient did not show any intercorrelation between the platelet adhesiveness and raised lipid fractions. These factors could be responsible for the atheroma resulting in large vessel occlusion.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The effect of racemic mephobarbital and its optical isomers on survival time of mice exposed to 5% O2was studied. There was an increase in survival time from 4.2 minutes to 12.6 minutes for 100 mg/kg of the anesthetically active (-) isomer and the racemic form, but no increase for 100 mg/kg of the inactive (+) isomer. Since it has been shown that there is no difference in brain concentrations between the isomers, we conclude that the barbiturate protective effect is bound to the anesthetic effect. All mice convulsed, and since the non-anesthetized animals convulsed earlier and stronger than the anesthetized, it was possible that barbiturate protection was accounted for by its anticonvulsant effects. Diazepam 7.5 mg/kg, while reducing convulsions to the same degree as barbiturates without producing anesthesia, only increased survival time to 6.2 minutes. Thus, the barbiturate protective effect is distinct from the anticonvulsant effect. It seems to be bound to a stereospecific receptor for both protection and anesthesia.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Unanesthetized macaque monkeys were subjected to middle cerebral artery (MCA) occlusion. Local cerebral blood flow (ICBF) was measured with a hydrogen clearance technique. Mean arterial blood pressure, arterial blood gases, and intracranial pressure were monitored serially. Two weeks after ischemic insult, a neuropathologic examination documented cerebral infarction and its relation to CBF recording sites. Unanesthetized monkeys hyperventilated and became hypocapneic, particularly after MCA occlusion (mean Paco2 fell from 33 to 26 mm Hg). Intracranial pressure remained normal except in massive fatal infarction, where it rose dramatically. Responses to MCA occlusion were strikingly variable; some animals showed little ICBF reduction and no deficit or infarction, while others sustained marked ICBF reduction with hemiplegia and massive fatal infarction. Extent of ICBF reduction correlated well with infarct size. Since the extent of ICBF reduction reflects collateral circulation, variation in collateral supply appears responsible for variation of infarction. Re-opening of MCA occlusion always led to restoration of normal or above normal ICBF. Thus, no evidence for impaired reperfusion was observed. Post-ischemic CBF markedly above normal was associated with eventual severe infarction. Restoration of MCA flow led to improvement of hemiparesis after moderate reduction in ICBF, but fatal infarction occurred despite restored flow after severe reduction in ICBF. "No reflow" was not observed. When ICBF fell below 12cc/100gm/min for 2 hours or longer, local infarction resulted. Flow above this infarction threshold prevented irreversible damage.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Cerebral blood flow autoregulation (CBFA) to changes in perfusion pressure has not been previously reported in the rat. A modification of the Kety and Schmidt technique employing133Xenon was used to measure cerebral blood flow (CBF) in paralyzed adult Sprague Dawley rats passively ventilated with 70% nitrous oxide and 30% oxygen. At a mean arterial blood pressure (MABP) of 121 ± 19 mm Hg, and a mean arterial Pco2of 36.2 ± 2.9 mm Hg, mean CBF was 103 ± 22 ml/min/100 gm of brain. CBF responses to hypercarbia were 4.9 ml/min/100 gm per mm Hg change in arterial Pco2. CBF was measured during steady state levels of hypo- and hypertension induced by phlebotomy, or by intravenous metaraminol, over the MABP range of 48-205 mm Hg. From a MABP of 80 to 160 mm Hg, CBF remained nearly constant, indicating the presence of CBFA. However, when MABP exceeded 160 mm Hg, CBF became pressure dependent, indicating a "breakthrough" of autoregulation in acute severe hypertension.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Cerebral ischemia was produced in gerbils by ligation of the right common carotid artery and the resulting clinical manifestations and pathological alterations, along with electroencephalographic findings, were followed from 30 minutes to 24 hours. Protein synthesis was evaluated with brain slices in vitro and subsequent cellular and subcellular fractionations. One group of animals developed clinical signs of cerebral ischemia and stroke very rapidly and often died within 12 hours. In these animals cerebral infarction was diffuse in the right side of brain within a few hours postoperatively and there was persistent suppression in the electroencephalographic recordings. Amino acid incorporation into proteins of subcellular fractions was decreased to 50% of the opposite side at 30 minutes and further declined to less than 10% in 8 to 10 hours. Another group of animals survived to 24 hours in spite of severe neurological manifestations, and protein synthesis was about 15% of the control side at 24 hours. The suppression of protein synthesis was observed both in the neuronal and neuroglial fractions indicating similar vulnerability of these cellular elements toward cerebral ischemia as shown with cerebral anoxia in the past. It was emphasized that the correlation of clinical manifestations and biochemical data is very important to extract meaningful information from biochemical investigations in this model.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Cerebral cortical blood flow was measured in rabbits with the hydrogen clearance technique. The reactivity to CO2, tested by changing the end tidal CO2(ETCO2) in steps from 2 to 6 volumes %, was highly dependent on the kind of anesthesia, being greatest under halothane and least under nitrous oxide. Reactivity to CO2in halothane-anesthetized animals also depended on arterial blood pressure, being greatest when pressure was below 70 mm Hg. Intravenous atropine blocked the increase in reactivity in halothane-anesthetized animals at low blood pressures. Conversely, intravenous eserine (physostigmine) greatly increased the reactivity to CO2in nitrous oxide-anesthetized animals. Precollicular decerebration considerably decreased CO2reactivity of halothane-anesthetized rabbits, while partial brain stem lesions that spared midline structures had no effect on CO2reactivity. It is concluded that a central neurogenic mechanism with a cholinergic link may be responsible, at least in part, for the cerebrovascular effect of CO2. Moreover, the cerebrovascular effects of halothane may result from stimulation of the same system.

ISSN:0039-2499    

出版商:OVID    

年代:1978

数据来源: OVID