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Biomedical subjects

A Maret

Publications and source records attributed to A Maret.

68 records · Page 4Linked to original sources
PubMed1981

[Comparison of the molecular forms of exonuclease and ribonuclease in normal human spleen].

Molecular forms of exonuclease and ribonuclease from normal human spleen were separated by preparative electrofocusing and characterized by their enzymatic properties. Six molecular forms (E1 to E6) of exonuclease can be separated by isoelectric focusing from human normal spleen. Properties of these molecular forms have been studied: substrate specificity, hydrolysis of paranitrophenyl-thymidine-3'-monophosphate, optimum pH and heat-stability. So two enzymatic groups can be separated: - an acidic group contained forms E2, E3, E4 hydrolysing at high level the paranitrophenyl-thymidine-3'-monophosphate, with optimum pH between 5.0 and 5.5. These three forms were heat labile at 50 degrees C and belong probably to the same isoenzymatic group. - a neutral or more alkaline group was represented by the forms, E1, E5 and E6. These forms hydrolysed at very low level the paranitrophenyl-thymidine-3'-monophosphate and were different by their optimum pH and heat-stability. So, these three forms do not belong to the same isoenzymatic group. Profiles of ribonuclease showed three molecular forms R1, R2 and R3 different from exonucleases by their isoelectric point, optimum pH, substrate specificity and overall heat-stability. These ribonuclease forms differed from one another in optimum pH and probably do not belong to the same isoenzymatic group.

Chemical Phenomena↗
PubMed1981

[Nonspecific phosphodiesterases of human leukocytes, blood platelets and serum].

Phosphodiesterases from blood cells and serum can be subdivided in several groups according to substrate specificity, optimum pH and effects of inhibitors: 1) Acidic phosphodiesterase activities were not inhibited by EDTA, represented the whole p3'T hydrolysing activity, but only a part of the activity hydrolysing the other substrates (p5'T was not hydrolysed at acidic pH). This acid phosphodiesterase activity was high in white blood cells and platelets but very low in serum. 2) Neutral phosphodiesterase activity was prevalent in leucocytes when BpP and BMP were used as substrates. 3) Alkaline phosphodiesterase activity was characterized by substrate specificity at optimum pH and distribution in cells and serum: in serum there are phosphodiesterases hydrolysing all checked substrates (p3'T excepted) at optimum pH 9.0, whereas in blood cells alkaline phosphodiesterase activities are very low for all substrates (excepted for p Phi Pn and p5'T). In each cell and serum we have determined, for all phosphodiesterase activities, the linearity of activity of versus time and versus protein concentration, the effect of substrate and effector concentration and the heat stability.

Blood Platelets↗
PubMed1980

[Separation by electrofocusing of the molecular forms of splenic beta-glucosidase in normal subjects and Gaucher's disease].

Electrofocusing allows to separate the beta-glucosidases from normal spleen in several molecular forms: a non specific beta-glucosidase form (pl 4.6) and two forms of beta-glucocerebrosidase (pl 5.0 and pl 6.5). beta-glucosidase and beta-glucocerbrosidase differ with regard to their thermal stability. In a spleen from a patient with non neuronopathis Gaucher's disease (type I or adult form), molecular whereas the non specific beta-glucosidase is not significantly decreased. Thus, the beta-glucocerebrosidase forms and the non specific beta-glucosidase are not coded by the same gene. The separation of molecular forms of beta-glucosidase allows to measure the part of specific beta-glucosidase activity in the assay of beta-glucocerebrosidase by artificial substrate, 4-methylumbeliferyl-beta-D-glucopyranoside.

Gaucher Disease↗
PubMed1979

[Molecular forms of human leukocytic alpha-galactosidase and N-acetyl-alpha-galactosaminidase].

1. Normal human leukocytes present three molecular forms of alpha-galactosidase (EC 3.2.1.22) separated using electrofocusing: a new major form IV (pI 4.0) characteristic of leukocytes and two forms that exist in other tissues, form I (pI 4.5) and form II (pI 4.0). 2. Normal human leukocytes present only one molecular form (pI 4.5) of N-acetyl-alpha-galactosaminidase (EC 3.2.1.49) corresponding to alpha-galactosidase form II. 3. In leukocytes from patients with Fabry disease, the electrofocusing shows that the alpha-galactosidase lacking corresponds to forms I and IV, while the residual activity corresponds to form II (or N-acetyl-alpha-galactosaminidase).

Acetylgalactosamine↗
PubMed1976

[The transfer of delayed hypersensitivity in mice].

Independently of histocompatibility between donors and recipients, delayed type hypersensitivity can be transferred with splenic cells from sensitized animals, inoculated locally in the foot pad. Cyclophosphamide given to recipients 48 hrs. before the cells increases significantly the intensity of the transferred delayed type hypersensitivity.

Animals↗
PubMed1975

[Modulation of delayed hypersensitivity by antibodies].

Immunsera against methylated bovine serum albumin (M-BSA) inoculated into mice before sensitization to M-BSA produced a diminution of the delayed hypersensitivity to M-BSA. Immunsera to some modified or native BSA did not produce the same effect which appears to be highly specific.

Animals↗
PubMedDate not supplied

[Effect of estrogens on arterial physiology and mechanisms of their atherosclerosis-protective effect in animals].

Two isoforms of oestrogen receptors (alpha and beta) have been identified in the cells of the arterial wall, and a heterogeneity of their expression according to the animal species, the vascular beds and the sex has been reported. Oestrogens can thus directly influence the vascular physiology through a 'genomic' mechanisms, but 'extra-genomic' mechanisms responsible for a short-term effect have also been suggested. Oestrogens potentiate endothelium-dependent relaxation through an increase in nitric oxide bioavailability (increase in its production and/or decrease in its degradation by superoxide anion according to the vascular beds). Endothelial 'dysfunction' (abnormality of the endothelium-dependent vasodilation) occurs in atheromatous arteries. Oestrogen replacement prevents and even corrects this endothelial dysfunction. In monkeys, this beneficial effect of oestrogens is not altered by coadministration of progesterone, but is abolished by coadministration of medroxyprogesterone. Finally, oestrogens prevent fatty streak deposit, and the mechanisms of this atheroprotective effect are being studied.

Animals↗