Cortical perfusion assessment with 123I-isopropyl amphetamine (123I-IAMP) in normal pressure hydrocepha lus (NPH).

NPH can be reversible after cerebrospinal fluid (CSF) diversion. In the past no reliable criteria could be defined to predict the successful outcome of CSF shunting. Several authors demonstrated an increased cerebral blood flow after lumbar puncture in patients with NPH, indicating an underlying impairment of cerebral circulation autoregulation.

[Protective effects of Ginkgo biloba extract on the early rupture of the hemato-encephalic barrier in the rat].

During the hours immediately following an hypertensive burst or a cerebral ischemia induced by the intracarotid administration of microspheres, damage to the blood brain barrier can be observed with molecules of low molecular weight, such as angiotensin, whereas albumin or large proteins will not yet have been able to cross over and there is virtually no edema. Gingko biloba extract causes the brain uptake index of angiotensin hypertensive animals. This effect is proportional to the dose of extract used (500-100 mg/kg).

[Cerebral glucose consumption. The effect of Ginkgo biloba extract].

Deoxyglucose is transported under the same conditions as glucose from blood to cerebral tissue. Deoxyglucose-6-phosphate, which cannot be neither metabolized nor eliminated, accumulates in cells. This accumulation is correlated with glucose consumption.

Evidence for the role of ammonia in the intracerebral transfer and metabolism of tryptophan.

After portacaval shunt in the rat, the transport of tryptophan and other neutral amino acids across the blood-brain barrier is enhanced. To determine the role of NH3 in the intracerebral transfer of tryptophan and serotonin metabolism, solutions containing either saline or NH3 or tryptophan or NH3 + tryptophan together were infused, respectively, into the internal carotid artery of rats in order to achieve blood levels similar to those observed after liver ischemia. After tryptophan infusion, a significant increase in the hypothalamic levels of tryptophan and 5-hydroxyindoleacetic acid was observed.

Psychometric tests in ageing.

In order to detect and analyze early cognitive disorders related to ageing, we selected a battery of psychometric techniques. This battery includes a generally accepted test (the PRM of A. Rey) and new computerized tests (reaction-time test and video objects test) designed by ourselves.

Age and learning: experimental and clinical aspects.

Memory loss and similar cognitive associated dysfunctions are commonly recognized as being the most serious symptoms of ageing and dementia. In this work, a deterioration of cognitive function which is appreciated in old rats (learning test in a maze--or, in aged humans, memory verbal test) is determined during the measurement of local cerebral blood flow and metabolism. In the animal, the disturbance by the learning test is observed by a decrease of blood flow in the hippocampus, diencephalon, and corpus striatum.

Multiparametric imaging of blood flow and metabolism after middle cerebral artery occlusion in cats.

In anesthetized adult cats, acute stroke was produced by transorbital occlusion of the left middle cerebral artery. A battery of imaging techniques was used for simultaneous evaluation of regional blood flow, glucose utilization, protein synthesis, pH, and the regional tissue content of glucose, ATP, and potassium. The electrophysiological impact of stroke was monitored by EEG frequency analysis and recording of somatosensory evoked potentials.

Learning and cholinergic neurotransmission in old animals: the effect of Hydergine.

In the present work, a study of the number of functional receptors has been made with 3HQNB given to resting awaken animals during a learning process. Ageing leads to a decrease in the ability of learning associated with an increase in the number of large movements. The number of cholinergic receptors is also reducel if we compare 22 month old animals with 4 month old animals maintained under usual conditions.

Iodoamphetamine as a new tracer for local cerebral blood flow in the rat: comparison with isopropyliodoamphetamine.

Rats were injected with iodoamphetamine synthesized and labeled with 125I or with 125I- isopropyliodoamphetamine , a molecule of established value for the determination of local cerebral blood flow. The blood kinetics, tissue distribution, and brain uptake index for each tracer exhibited practically no differences. Autoradiographic quantification of the local cerebral blood flow, calculated according to the microsphere model, produced identical results for both molecules.

Simultaneous study of haemodynamic, metabolic and behavioural sequelae in a model of cerebral ischaemia in aged rats: effects of nicergoline.

Unilateral cerebral ischaemia was induced in 18-month-old Long-Evans rats by injection of 2,000 labelled microspheres (phi 50 microns) into the carotid blood stream. This results in an ipsilateral decrease in cerebral blood flow, development of severe oedema and modifications of glucose uptake and consumption. Furthermore, this ischaemia led to a deterioration of the avoidance response in conditioned animals.

Simultaneous study of cerebral blood flow, vascular bed and deoxyglucose in aged rats. Effects of two dihydrogenated rye ergot alkaloids.

The influence of aging and the effects of treatment with dihydrogenated rye ergot alkaloid on cerebral hemodynamics and metabolism were studied in Long-Evans rats. Cerebral blood flow (CBF) was not affected by aging whereas the vascular bed and the uptake of deoxyglucose were significantly lower in aged than in young rats. 20 days after ligation of a carotid artery the blood flow on the same side of the brain, the vascular bed and the uptake of deoxyglucose were significantly lowered in aged rats as opposed to young rats.

[Learning, hemodynamic and metabolic attendant effects in aged animals after an acute ischemic accident].

The effects of ageing in normal and pathological rats were studied. Learning (spatio-temporal test) was measured simultaneously with the local cerebral blood flow, determined by a diffusible indicator (iodoantipyrine) and with the uptake and consumption of glucose, determined by the deoxyglucose. Normal ageing disturbs the learning with a decrease in acquisition speed and an increase in the number of errors.

[Chemical and pharmacological aspects of cerebral cellular tracers].

Among the iodophenylalkylamines studied and labelled with iodine 125 or iodine 123, N-isopropyl-iodo-amphetamin (IAMP) was selected and proposed as tracer for blood flow, a "chemical embolus" having almost 100% extraction in the brain. A new way of obtaining N-isopropyl-p-iodo-amphetamin is proposed and the easily-applied exchange reaction with iodine 125 or 123 gives a product with a radiochemical purity of more than 96% and an unexchanged radioactive iodine content of less than 1%. The pharmacokinetic study of this product in the Wistar rat showed distribution in three compartments and the appearance of a steady state by the fourth minute.

Demonstration of vascular redistribution after carotid clamping in rats.

In Long Evans rats, the vertebral arteries supply only the brain stem. Simultaneous application of clamps to both carotid arteries results in a considerable fall of cerebral blood flow and eventually death. If an interval of about 4 days is allowed between the clamping of the 2 carotids, redistribution of blood flow takes place.

Cerebral blood-flow tomography: xenon-133 compared with isopropyl-amphetamine-iodine-123: concise communication.

Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used. The Xe-133 flow maps are essentially based on the average Xe-133 concentration over the initial 2 min during and after an inhalation of the inert gas lasting 1 min.

Effects of naftidrofuryl on cerebral hemodynamics, metabolism and function after a retracted ischaemia.

Unilateral microemboli were formed in the brains of Long Evans rats by means of an intracarotid injection of microspheres (50 mu). This embolization resulted in a decrease in blood flow, severe cerebral oedema and a modification of glucose uptake. Furthermore, these microemboli affected a conditioned avoidance response.

[Cerebral blood flow metabolism and behavior following cerebral infarction in the awake rat (author's transl)].

In the awake rats, a cerebral ischemia was performed by means of 2,000 microspheres administered into the internal carotid via a chronic catheter. After a coma lasting for a few minutes and a 24-48 h palsy, the Long Evans rats gradually recover a normal behavior. The acquisition of an avoidance response is deeply disturbed by microembolization but the capacities of memorization reappeared with the regression of oedema.

[Cerebral ischemia after ligature of both carotid arteries in rats: effect of ginkgo biloba extracts (author's transl)].

Simultaneous ligature of both carotid arteries in Long Evans rats results in death for all animals. 50% of the animals survive if the ligatures are separated by a four-day interval. Studies of variations in cerebral blood flow according to the time interval between the two ligatures show that alternative vascularization develops and that the balance between both hemibrains is restored.