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Biomedical subjects

P Celsis

Publications and source records attributed to P Celsis.

51 records · Page 3Linked to original sources
PubMed1990

Lateral asymmetries in primary degenerative dementia of the Alzheimer type. A correlative study of cognitive, haemodynamic and EEG data, in relation with severity, age of onset and sex.

Cognitive, haemodynamic and EEG lateral asymmetries have been quantified in 20 patients with Primary Degenerative Dementia (PDD) and in 20 age-matched normal volunteers. Normalized asymmetry scores were calculated from the data obtained with a test battery, with SPECT and with quantitative EEG. Significant correlations were found between cognitive, haemodynamic and EEG scores in patients but not in controls. The functional asymmetries correlated to the Mini Mental State (MMS) score, the lowest MMS values being observed in patients with right hemisphere predominant impairment. Besides, in these patients, a significant correlation was observed between age at onset and MMS score so that, in this subgroup only, the earlier the onset the more severe the disease. Finally, the prevalence of pronounced functional asymmetry seemed to be higher in our male patients. Our study shows that lateral asymmetries are frequent in patients with PDD and that preferential lateralization of the abnormalities should be given further attention, especially with regards to age, sex and overall severity.

Adult↗
PubMed1989

[Cerebral imaging and dementia].

Modern imaging techniques undoubtedly are of value when applied to the study of dementia. This value, however, varies with the technique utilized, and one must distinguish between acquired and potential knowledge. Morphological imaging with computerized tomography or magnetic resonance detects or confirms certain causes of dementia (tumours, lacunae, hydrocephalus with normal CSF pressure), but it is still not sensitive and specific enough to be very useful in primary dementias. Functional imaging (essentially with emission tomography) has already provided interesting data in the study of degenerative dementia (correlations with neuropsychology, subtyping), but what is most promising is its possibilities in the physiopathological approach of the disease.

Dementia↗
PubMed1989

SPECT study of cerebral blood flow reactivity after acetazolamide in patients with transient ischemic attacks.

We investigated 15 patients with one or more transient ischemic attacks (TIAs) in the internal carotid artery territory within the month following the most recent TIA. Cerebral blood flow (CBF) was measured by single-photon emission computed tomography, using intravenous xenon-133 before and after injection of 1 g acetazolamide. Six patients had severe carotid stenosis or occlusion; the other nine patients had no significant carotid lesions. Twenty age-matched volunteers free of neurologic symptoms or history were used as controls. Mean CBF in the sylvian region was not significantly different between patients and controls. Seven patients exhibited a focal hypoperfusion at rest in the symptomatic hemisphere, and their hypoperfused areas were hyporeactive after administration of acetazolamide. Seven other patients exhibited hyporeactive areas after acetazolamide administration while their CBF tomograms at rest were normal. Thus, CBF abnormalities were detected in 14 of the 15 patients. Our findings suggest that CBF measured early after acetazolamide administration could be useful to confirm the clinical diagnosis of TIA. In the nine patients with no significant lesion of the internal carotid artery, the areas of hypoperfusion were small and were probably related to the focal ischemic event. In the six patients with severe lesions of the internal carotid artery, abnormalities were of variable size and intensity but were often large and pronounced. The discrepancy between these two subgroups of patients could be ascribed to the hemodynamic influence of the internal carotid artery lesions. Moreover, our findings may provide some insight into the pathophysiology of TIAs.

Acetazolamide↗
PubMed1988

[Effect of bromocriptine on cerebral blood flow in Parkinson's disease].

We measured regional cerebral blood flow (CBF) with single photon emission computed tomography and Xenon 133 in 8 patients with Parkinson's disease (stages I or II) before and after acute oral administration of 10 mg bromocriptine. Moreover, Columbia University Rating scale and neuropsychological tests were assessed before and after drug administration. Bromocriptine induced a significant (p less than 0.01) increase in CBF (+ 12 p. 100) in all the regions studied unrelated to pCO2 variations. The Columbia motor scale score decreased (by 16 p. 100) whereas those on the neuropsychological tests did not vary. There was no relationship between the improvement in motor performance and the increase in CBF. The results suggest that the effect of bromocriptine on CBF is not mediated by an action on the major dopaminergic pathways in the brain but rather by a direct effect on dopaminergic receptors located on cerebral vessels.

Administration, Oral↗
PubMed1987

Levodopa-induced regional cerebral blood flow changes in normal volunteers and patients with Parkinson's disease. Lack of correlation with clinical or neuropsychological improvements.

Single photon emission computed tomography was used to measure regional cerebral blood flow in six normal subjects and 12 patients with Parkinson's disease, before and after acute oral administration of levodopa. The drug induced a significant increase in cerebral blood flow both in controls and patients. Before levodopa, there was no significant difference between the groups, either in flow values or in their pattern. The clinical effects of levodopa were not related to the hemodynamic changes. The results suggest that measuring the flow response to levodopa is not appropriate to demonstrate variations in central dopaminergic receptor sensitivity in man.

Administration, Oral↗
PubMed1987

Focal cerebral hypoperfusion and selective cognitive deficit in dementia of the Alzheimer type.

Regional cerebral blood flow was investigated using single photon emission computed tomography and xenon-133 intravenous injection in six patients with dementia of the Alzheimer type (DAT) with atypical focal clinical presentation, and in 20 age-matched healthy volunteers. The patients had a progressive and preponderant cognitive deficit and a focal hypoperfusion that correlated with the neuropsychological findings, whereas the average flow did not significantly differ from that of controls. The assessment of concordant haemodynamic and neuropsychological focal abnormalities could be useful in the diagnosis of atypical cases of DAT.

Aged↗
PubMed1985

Measurement of cerebral circulation time in man.

A simple, inexpensive method for measuring the cerebral circulation time (CCT) was developed. The CCT was considered to be equal to the time that an intravenously injected bolus of sodium pertechnetate Tc 99m took to go from the subclavian artery to the posterior venous confluence. The dilution curves were externally recorded at these two vessels. Particular attention was given to the curve treatment. The computer programmes were specially conceived in order to detect and, if possible, correct the experimental curve defects. Several reliability criteria were also defined in order to test the validity of each measurement. From a physiological point of view, the CCT is equal to the ratio of the global cerebral blood volume to the global cerebral blood flow. Thus, it can be widely applied in clinical research. For example, in a study of the relationship between CCT and age, sex and light cerebrovascular impairment, the technique was sensitive enough to discriminate between healthy subjects and patients suffering from-transient ischemic attack, or regressive stroke, and to show the action of a drug on the cerebral circulation in such patients.

Adult↗
PubMed1981

A method for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations.

Emission tomography of positron or gamma emitting inert gases allows calculation of regional cerebral blood flow (rCBF) in cross-sectional slices of human brain. An algorithm is presented for rCBF calculations from a sequence of time averaged tomograms using inhaled 133Xe. The approach is designed to avoid loss of information in brain areas with low flow rates. It is based on linearizing and scaling the early isotope distribution picture (recorded from 0 to 2 min) in rCBF units of ml/100 g/min. This is done by calculating the time constant ki for pixels with high count rate using the entire sequence of four 1 min pictures and using a fixed value for the brain:blood partition coefficient, lambda. The method is essentially based on the bolus distribution principle, and it allows the estimation of blood flow in ischemic areas. Application to positron emission tomography is discussed.

Cerebral Infarction↗
PubMed1980

Accuracy of methods for calculating cerebral blood flow from intracarotid xenon-133 injection.

The accuracy of the three commonly used methods, the initial slope analysis, the stochastic analysis, and the compartmental analysis, for calculating mean cerebral blood flow from xenon-133 clearance curves was studied with the use of computer-generated and real curves. The accuracy of calculation was affected by the cutoff time of the curve, by the level of the compartmental blood flows to white and gray matter and by the ratio of these flow levels, by the relative weight of gray matter, and by the choice of the method of calculation. None of the methods was clearly superior to the others. Each had its own defects that render it more or less suitable for different situations. All three methods generally overestimated mean cerebral blood flow. This overestimation was greater the lower the flow. A curve-fitting index was devised which can be used to check the validity of the bicompartmental model when using compartmental analysis. This same index can provide, though not always, an estimate of the error in the calculation of mean cerebral blood flow when an optimization method is used.

Cerebrovascular Circulation↗
PubMed1979

Scattering of cerebral blood flow estimates using 133Xe intracarotid injection.

Computer-generated and real curves were used to study the random error in the blood flow estimates calculated from xenon-133 cerebral clearance curves. The initial count rate affects the scattering under a threshold of 5,000 counts/s, but above this figure its influence is negligible. Flow values, relative weight of gray matter, and processes of analysis have also an effect. For the stochastic analysis, a theoretical standard deviation calculable from each experimental curve was proved. For other methods, empirical formulas were established. Using these formulas, intervals of uncertainty can be calculated allowing a useful comparison of the results obtained on the same patient, from different areas or from subsequent tests. Such intervals also allow the comparison of mean flow values obtained from a particular curve by the three usual processes of analysis. With high initial count rates, more than 75% of the intervals of uncertainty are disjointed. This suggests that the random error plays little part in the differences observed.

Cerebrovascular Circulation↗