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Biomedical subjects

Y Michotte

Publications and source records attributed to Y Michotte.

103 records · Page 6Linked to original sources
PubMed1981

Atrophic autoimmune thyroiditis: relationship between the clinical state and intrathyroidal iodine as measured in vivo in man.

The intrathyroidal iodine (ITI) was measured by means of the x-ray fluorescence method in 58 patients suffering from atrophic autoimmune thyroiditis (AAT). They were divided into 4 groups according to their basal T4, basal TSH, and the peak TSH response after TRH administration. Forty-eight normal subjects served as controls. A progressive fall of ITI was found, with less ITI in the first grade AAT patients as compared to the controls. A negative correlation between basal TSH and ITI could be shown. These data support the concept of a graded evolution of AAT, linking the clinical state to the ITI. The results also suggest that, with the hemagglutination techniques used for the determination of antithyroglobulin antibodies and antithyroid microsomal antibodies, positively at a dilution of 1:25 and 1:100, respectively, should be regraded as significant.

Autoimmune Diseases↗
PubMed1977

A morphological and chemical study of calcification of the choroid plexus.

Human choroid plexus was submitted to low temperature ashing (LTA) in order to isolate the calcification. The ashing residue was then subjected to morphological, chemical and structural studies using technics such as scanning electron microscopy, flame and flameless atomic absorption spectrometry, infrared spectrometry and X-ray diffraction. Morphologically, the calcification consisted of wound-up fibers forming granules with a diameter of 0.05 to 0.15 mm. The concretions were identified as cristalline Ca3(PO4)2 and hydroxylapatite. The content of trace elements was high, but within the limits found in other biological apatites. In some cases, however, the Fe content exceeded these limit values.

Calcinosis↗
PubMed1977

A morphological and chemical study of calcification of the pineal gland.

A general scheme of analysis for the investigation of minute calcification is presented. After low temperature ashing, the samples are subjected to chemical, structural and morphological study, using atomic absorption spectrometry, infrared spectrometry, X-ray diffraction and scanning electron microscopy. Details about the calcification of the human pineal gland are given. The content of trace elements is very high, but within the limits found in other biological apatites. It is concluded that calcification of the pineal is a more general occurence than has been realized.

Brain Diseases↗
PubMed1977

Molecular connectivity and retention indexes.

The molecular connectivity indexes, chi, of some alcohols, ethers, esters, and ketones did not correlate very well with their retention volumes in some GLC systems. It was concluded that the utility of chi for the prediction of biological activities could prove rather limited.

Chemical Phenomena↗
PubMed1975

Brain calcification in a case of acute lymphoblastic leukaemia.

Cortical calcifications, ween on X-ray in the brain of achild suffering from leukaemia, were submitted to morphological and chemical analysis. The morphology was studied by a combination of low teperature ashing and microscanning. The calcification principally affected axons and capillary walls and consisted of spherules amalgamated into hollow cylinders. The results of chemical analysis of the calcified material were compared and structure of both types of calcification were similar, but the Mn concentration washigher in case of Fahr's disease. X-ray diffraction showed that the calcification consisted of amorphous calcium phosphate and acid calcium orthophosphate, most probably precursors of hydroxyapatite..

Brain↗
PubMed1975

The chemical composition of idiopathic nonarteriosclerotic cerebral calcifications.

Calculi from a case of cerebral idiopathic nonarteriosclerotic calcification (Fahr's disease) were examined. The stone consists of hydroxyapatite and possesses a typical structure: the calcification process seems to be initiated by the formation of small round bodies that are cemented to each other to form the final stone. Calcified vessels are also present, but seem to be a secondary effect. From a comparison with other calcifications, it is concluded that no pathologic significance should be attached to the relatively high levels of trace metals such as zinc, iron, copper, magnesium, lead, and others, with the possible exception of manganese. The organic matrix of the stone contains large quantities of protein. On hydrolysis of this fraction, an important unidentified ninhydrin-positive peak was found. No mucopolysaccharides were found.

Activation Analysis↗
PubMedDate not supplied

Catechol is the major product of salicylate hydroxylation in 1-methyl-4-phenylpyridinium ion treated rats.

Salicylate hydroxylation using hydroxyl free radicals results into formation of 2,3-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid and catechol. Inspite of the fact that in vitro experiments have shown that catechol is a minor product, we have shown by these in vivo studies that it is a substantial product. Since catechol as well as 2,3-dihydroxybenzoic acid have not been found to be produced enzymatically from salicylates, they appear useful as in vivo indicators for monitoring hydroxyl free radicals. Administration of 1-methyl-4-phenylpyridinium ion (MPP+) to rat striatum using microdialysis results into the formation of hydroxyl radicals. Salicylate perfusion enables the estimation of the three derivatives cited above. They increased significantly after MPP+ administration in comparison to the baseline values, with catechol being the most significant. The maximum amounts were achieved 60 min after MPP+ administration, and the mean percentage increase at this time point were 83.1% for 2,3-DBA (n = 6, P = 0.005), 81.25% for 2,5-DBA (n = 6, P = 0.011) and 1228.8% for catechol (n = 4, p = 0.00008). MPP+ caused substantial decrease of dopamine metabolites. Dihydroxyphenylacetic acid decreased to 13% and homovanillic acid to 11.4%. We conclude that catechol is an important indicator of hydroxyl free radical formation in this animal model which is well suited to study the role of free radicals in Parkinsonism.

1-Methyl-4-phenylpyridinium↗
PubMedDate not supplied

The use of microdialysis for the determination of plasma protein binding of drugs.

Microdialysis sampling was used for the determination of the protein binding and the free therapeutic drug concentration of drugs in plasma in vitro. Several drugs with varying extent of protein binding and for which the plasma monitoring is important were studied. To mimic the in vivo situation, an artificial blood vessel was constructed and filled with spiked plasma circulating at the flow rate of human blood at 37 degrees C. The microdialysis probe (16 mm membrane length, 20000 MW cut off) was placed in the vessel and perfused with 0.9% NaCl at 5 microliters min-1. Dialysates were collected every 10 min and were analysed by reversed-phase LC with UV detection. The free concentration of the drug was calculated by correcting the concentration in the dialysate for the recovery of the probe, which was also determined in the artificial blood vessel after the experiment. The data confirm that microdialysis is a valid alternative technique for the determination of protein binding or free therapeutic plasma concentration of drugs on a comparative basis. Reference to literature values indicates that the results of the proposed method correspond reasonably well with accepted values.

Acetaminophen↗
PubMedDate not supplied

Alzheimer's disease: biological diagnosis.

The authors discussed the possible clinical chemical diagnosis of Alzheimer's disease in function of the well established biochemical changes in different neurotransmitter systems.

Alzheimer Disease↗