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Biomedical subjects

P Loiseau

Publications and source records attributed to P Loiseau.

305 records · Page 17Linked to original sources
PubMedDate not supplied

[Peripheral neuropathies i- Waldenstrom's disease. Histological and ultrastructural studies of 5 cases].

In four cases it was the existence of peripheral neuropathy which led to the discovery of macroglobulinemia within an interval from 1 to 11 years. The treatment of the disease also markedly improved the peripheral neuropathy in three cases. Two patients died. Two of the biopsies of the peripheral nerve showed infiltration by atypical lymphocytes. Ultrastructural changes in the five cases were variable. Marked axonal involvement in the two cases with cellular infiltration. In one of these two cases it was combined with segmental demyelinization. This lesion was clearly predominant in the three other cases. In one of them demyelinization occurred in a very peculiar way with dilation of the internal part of the mesaxone going on in the most peripheral layers of the myelin. Discussion of the mechanisms of the involvement of the peripheral nervous parenchyma in Waldenström's disease. Cellular infiltrations, amorphous deposits, changes in the capillaries and macroglobuline may occur.

Adult↗
PubMedDate not supplied

[Role of folic-acid deficiency in deficiency diseases of the nervous system. Apropos of 12 cases including an anatomo-clinical case].

The authors report 12 cases of neurological syndromes due to folic acid deficiency, due in 8 cases to chronic alcoholism. In 5 cases there was polyneuritis, 3 cases had cerebellar atrophy, whilst 4 patients had subacute combined degeneration of the cord. Folic acid deficiency occurred alone in five cases out of twelve, as in 3 cases vitamin B1 deficiency was associated, and in four cases there was malabsorption of vitamin B12. A neuropathological study of these cases showed: 1) moderate involvement of the mamillary tubercles as observed in deficiency encephalopathies. 2) severe peripheral nerve involvement especially of axonal type. 3) involvement of the anterior horns of the spinal cord with appearances of central chromatolysis and a few atrophic neurones.

Adult↗
PubMedDate not supplied

[Use of surviving infectious larvae of Dipetalonema dessetae in study and research on filaricidal substances].

Dipetalonema dessetae in Proechimys oris, the natural final host is a rodent filariasis model used as an in vivo antifilarial screening test. The laboratory vector is Aedes aegypti. Infective larvae L3 isolated from the intermediate host develop and remain healthy for up to 30 days in a biphasic culture medium composed of a cell feeder layer (L 929) and RPMI 1640 supplemented with foetal calf serum. This culture technique has enabled us to screen antifilarial compounds on a new in vitro test. This model has been tested to several pharmacological classes of anthelmintics and effective concentrations 90% are given: diethylcarbamazine 430 mg/l, suramin 490 mg/l, Mel W 3.5 mg/l, mebendazole 78 mg/l, flubendazole 45 mg/l, levamisole 0.55 mg/l, morantel 0.62 mg/l, ivermectin 1.2 mg/l, amoscanate 2.3 mg/l. In vitro test response is remarkable for neurotoxic anthelmintics and nitro-compounds. Furthermore, all compounds considered as reference filaricides are active. For each compound, the in vitro and in vivo results have been compared to appreciate usefulness as well as limits of this in vitro test.

Animals↗
PubMedDate not supplied

Respiratory function in recent pulmonary sarcoidosis with special reference to small airways.

This study was designed to evaluate airway dysfunction in relation to duration of disease in patients with pulmonary sarcoidosis for less than two years. Twenty four subjects with recent disease were compared with nine subjects with disease of more than two years' duration. They underwent lung function testing (lung volumes, lung transfer factor for CO and pulmonary mechanics). Small airway function was assessed using frequency dependence of compliance, closing volume, nitrogen single breath test and flow-volume curves breathing air and helium-oxygen mixture. Airway dysfunction was seen in pulmonary sarcoidosis even in some patients with recent disease and it became more evident in disease of longer duration. The results suggest small airway involvement. The frequency of airway dysfunction is difficult to evaluate, varying from estimates of 0% using flow-volume curves to 79% with frequency dependence of compliance. This apparent discrepancy could be explained by the consequences of parenchymal involvement leading to inhomogeneities in distribution of compliance, and of elastic lung recoil. We conclude that patients with recent sarcoidosis are probably affected by intrinsic small airway disease, but an increase in elastic recoil often conceals its consequences. The airway disease may not be apparent using conventional function tests and published predicted values.

Adult↗
PubMedDate not supplied

Analysis of parent drug-metabolite relationship in the presence of an inducer. Application to the carbamazepine-clobazam interaction in normal man.

An increase in drug metabolic clearance results in a decrease in concentration of parent drug but the effect on concentration of metabolite has been unclear. The effect of increases in the clearance of parent drug and/or metabolite upon the metabolite concentration, metabolite-to-parent drug concentration ratio, and fraction metabolized is described theoretically. It is shown that several combinations of increases in specific clearances can lead to qualitatively similar effects on steady state concentration of metabolite. The effect of increases in metabolic clearances of the clobazam-norclobazam system caused by carbamazepine treatment was studied in normal volunteers. The steady state concentration of metabolite (norclobazam) increased 1.4-fold and the ratio of metabolite to parent drug increased 4-fold. These effects of carbamazepine on clobazam-norclobazam pharmacokinetics could be a result of five theoretical cases. It is concluded that at least the formation clearance of norclobazam was increased. Carbamazepine treatment caused at least a 4-fold increase in the N-demethylation clearance of clobazam. It was also deduced that, in the baseline state, no more than 70% of the clobazam dose was metabolized to norclobazam, even though the norclobazam concentration was more than twice the clobazam concentration.

Adult↗
PubMedDate not supplied

Lung transfer factor for carbon monoxide measured during a slow single breath without breath-holding and during slow exhalation.

We considered whether a slow single breath with neither breath-holding nor carefully controlled flows could provide estimates of lung transfer factor for CO (TLCO) similar to those obtained with the usual standardized single breath technique. This technique requires actual flow rates and volume variations to be taken into account [10], as well as the use of a fast CO analyser and computerized calculations. TLCO values found with this method (TLCOsb) for 5 normal subjects and 29 patients with various respiratory diseases did not differ from those obtained with the standardized test (p less than 0.001). TLCO was also measured during exhalation only, by the use of a single compartment, constant TLCO equation and a computational procedure which provided a mean TLCO value for a given expired volume range (TLCOex). A unique TLCOex was sufficient to account for the whole exhalation in normal subjects and certain patients. In most patients two TLCOex were necessary, one for large lung volume after dead space washout and the other one accounting for the second half of expiration until closing volume. Most TLCOex were larger than TLCOsb calculated during the same slow breath. This over-estimation was found to be correlated (p less than 0.001) with the phase III argon slope. In patients where two TLCOex values were required to describe the exhaled CO course, we found that TLCOex decreased with lung volume. This decrease was also correlated with the argon slope (p less than 0.001). The observed difference between TLCOsb and TLCOex values and the decrease of TLCOex with lung volume probably reflect inhomogeneous ventilation distribution.

Adult↗
PubMedDate not supplied

Model systems for oxidative drug metabolism studies. Catalytic behavior of water-soluble metalloporphyrins depends on both the intrinsic robustness of the catalyst and the nature of substrates.

Sulfonated manganese and iron porphyrins have been used as catalysts in attempts to mimick the oxidation of acetaminophen and two ellipticine derivatives by horseradish peroxidase. Cofactors were potassium monopersulfate for the synthetic catalyst and hydrogen peroxide for the natural enzyme. Hindered metalloporphyrins, i.e. with ortho positions of the meso-phenyl rings substituted with methyl groups [iron(III) and manganese(III) derivatives of octasodium mesotetrakis(3,5-disulfonatomesityl)porphyrin], were shown to be at least 10 times more robust than unsubstituted derivatives [iron(III) and manganese(III) derivatives of tetrasodium meso-tetrakis(4-sulfonatophenyl)porphyrin] when activated in the absence of substrate. The catalytic activity depends on the nature of the substrate as shown by a decrease or an increase in reactivity observed, respectively, in the oxidation of acetaminophen or ellipticine derivatives catalyzed by hindered metalloporphyrins compared with nonhindered ones. Only sterically hindered metalloporphyrins, even in the case of lowered reactivity, were allowed to mimick the behavior of horseradish peroxidase when activated in the absence of substrate (stability toward autodegradation) and in the course of repeated infusion of substrate (retained catalytic activity as time advances).

Acetaminophen↗