Biomedical subjects

B Mazoyer

Publications and source records attributed to B Mazoyer.

78 records · Page 5Linked to original sources

PubMed1987

Cortical hypometabolism and its recovery following nucleus basalis lesions in baboons: a PET study.

The cerebral metabolic rate for glucose was measured serially with positron emission tomography and [18F]fluorodeoxyglucose in five baboons with stereotactic electrocoagulation of the left nucleus basalis of Meynert (NbM). Four days after lesion, a significant metabolic depression was present in the ipsilateral cerebral cortex, most marked in the frontotemporal region, and which recovered progressively within 6-13 weeks. These data demonstrate that adaptive mechanisms efficiently compensate for the cortical metabolic effects of NbM-lesion-induced cholinergic deafferentation. Moreover, unilateral NbM lesions also induced a transient reduction in contralateral cortical metabolic rate, the mechanisms of which are discussed. Explanation of these effects of cholinergic deafferentation in the primate could further our understanding of the metabolic deficits observed in dementia of the Alzheimer's type.

Animals↗

PubMed1987

Kappa as an index of reproducibility: distribution under the null-hypothesis.

The authors report a Monte-Carlo study of the properties of the weighted Kappa (Kw) statistic under the null-hypothesis and the assumption of equal marginal distributions, two hypotheses required in order to use Kw as an index of reproducibility. Different factors that may affect the Kw distribution are investigated: sample size, choice of the set of weights, number of levels of the rating scale and shape of the marginal distribution. Convergence towards the asymptotic distribution is studied and confidence limits are derived. For these latter, except in the uniform marginal distribution case, the use of values obtained by simulation instead of asymptotic estimates appears to be necessary for sample sizes of 30 or less.

Epidemiologic Methods↗

PubMed1984

99m Technetium labelled heparin: potential value as a tracer of heparin activity in pharmacokinetic and biodistribution studies.

Pharmacokinetics and biodistribution of 99m Technetium (99mTc) labelled heparin were studies to assess its value as a tracer of heparin kinetics in comparison with unlabelled heparin. In vitro, the stability and labelling efficiency (98%) of the labelled drug were excellent and elution was minimal. In vivo, after I.V. infusion of the drug, there was no difference in the same animal between anticoagulant activity measurements and radioactive countings, both displaying a plasmatic biexponential pattern (T1 = 2.9 minutes, T2 = 76 minutes). Biodistribution studies showed primarily liver, spleen and kidney accumulation, with no thyroid uptake. The advantages of this technetium labelling may therefore be used for the heparin drug in various experimental and pathological situations even in humans.

Animals↗

PubMed1980

[The diagnosis of traumatic rupture of the aorta. 36 cases (author's transl)].

Thirty six cases of traumatic rupture of the thoracic aorta (TRA) were diagnosed during the hours following the accident responsible. Rupture was situated at the aortic isthmus in 32 cases, the ascending aortic in 2 cases, the arch of the aorta in 1 case and the descending sub-isthmic aorta in 1 case. Ten patients had no rib fractures. In 16 patients not undergoing surgery before 20th hour after the trauma, 10 died of secondary rupture. The course of a TRA is thus unpredictable and it is of fundamental importance to make the diagnosis and undertake appropriate surgical treatment immediately. The essential clinical sign is a difference in blood pressure between the upper and lower limbs (6 6%). Radiological signs suggestive of TRA are, in a plain PA chest film : widening of the mediastinum (92 %), poor visibility of the knuckle of the aorta (89 %), left haemothorax (67 %), deviation of the trachea to the right (55 %) and lowering of the left main bronchus (47 %). The slightest suspicion of a TRA should lead to aortic angiography preferably via an arterial approach (humeral or femoral), or intravenously. Surgical treatment should not be delayed.

Aorta, Thoracic↗

PubMedDate not supplied

VoxeLine: a software program for 3D real-time visualization of biomedical images.

The architecture and implementation of VoxeLine, a new interactive environment for display and analysis of 2D and 3D images in real-time, is discussed. This modular software project comprises two main parts: a user part (without programming expertise) and a programming part which permits its adaptation to specific problems. VoxeLine has the ability to deal with almost all sorts of data types encountered in the biomedical field (e.g. images, vectors). Another important feature is its ability to show datasets in all directions without duplicating data into the main memory. This feature allows VoxeLine to be used on machines with limited memory capacities and power. Real-time 3D manipulations (10 Hz for a 256 x 256 x 124 MRI dataset) are possible on a classic monoprocessor architecture such as a personal computer.

Color↗

PubMedDate not supplied

A four-dimensional probabilistic atlas of the human brain.

The authors describe the development of a four-dimensional atlas and reference system that includes both macroscopic and microscopic information on structure and function of the human brain in persons between the ages of 18 and 90 years. Given the presumed large but previously unquantified degree of structural and functional variance among normal persons in the human population, the basis for this atlas and reference system is probabilistic. Through the efforts of the International Consortium for Brain Mapping (ICBM), 7,000 subjects will be included in the initial phase of database and atlas development. For each subject, detailed demographic, clinical, behavioral, and imaging information is being collected. In addition, 5,800 subjects will contribute DNA for the purpose of determining genotype- phenotype-behavioral correlations. The process of developing the strategies, algorithms, data collection methods, validation approaches, database structures, and distribution of results is described in this report. Examples of applications of the approach are described for the normal brain in both adults and children as well as in patients with schizophrenia. This project should provide new insights into the relationship between microscopic and macroscopic structure and function in the human brain and should have important implications in basic neuroscience, clinical diagnostics, and cerebral disorders.

Adolescent↗