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M Clerc

Publications and source records attributed to M Clerc.

At least 73 records · Page 4Linked to original sources
PubMed1990

Free malondialdehyde determination by HPLC applied to microsomal studies.

Malondialdehyde (MDA) is a product of lipid peroxidation in vivo. The most widely employed method for determination of free MDA is based on its reaction with thiobarbituric acid (TBA) which produces a pink pigment with an absorption maximum at 532-535 nm. However, quantitation of MDA is limited by its lack of specificity and a high performance liquid chromatographic (HPLC) method was recently developed in several laboratories. In the present study, free MDA levels were measured, after TBA reaction, spectrophotometrically and by HPLC in microsomes of different tissues from rats fed a vitamin A-deficient diet or not for 8 weeks, and treated or not with carbon tetrachloride. Incubation in vitro with NADPH (0.25 mM) or ascorbate (0.50 mM) in the presence of Fe2+ (5 microM)-ADP (0.5 mM), allowed us to estimate the total amount of enzymatic or non enzymatic lipoperoxidation. The MDA amount determined by HPLC is significantly lower than the TBA-reactive substances (TBA-RS) calculated spectrophotometrically as MDA equivalents. Moreover, HPLC separations performed on a mu Bondapack C18 column with a mobile phase of methanol/water 45/55 (v/v), containing 1% cetrimide revealed that three chromogens are present in microsomes incubated with ascorbate or NADPH. The TBA-RS visible spectra of microsomes incubated with activator are complex with an absorption maximum at 533 nm, which is specific for the MDA-TBA chromogen, and one at 450 nm. Identification of these TBA-RS, different from the MDA-TBA complex, is under investigation in our laboratory.

Animals↗
PubMed1990

Free radical inhibitor effect of retinol after carbon tetrachloride intoxication in the rat.

A study was conducted to explore the free radical inhibitor effect of retinol in Male Wistar rats. When retinol-deprived animals were considered retinol-depleted (after a period of 8 weeks), rats of each group, control and depleted, received an intraperitoneal injection of mineral oil (5 ml/kg body weight) or an equivalent volume of 20% carbon tetrachloride (CCl4) dissolved in mineral oil. The animals were killed by decapitation 4 h after administration of CCl4 and liver, heart, spleen, brain and testes were quickly removed. Minced tissues were homogenized and microsomes were prepared; vitamins A and E were monitored and malondialdehyde (MDA) content was estimated. Retinol-depleted rats showed an hepatic vitamin A level less than 10 pmol/mg protein, compared to control rats (15-45 pmol). In all hepatic preparations, we found low vitamin E levels (100-1300 pmol/mg protein). MDA production increased significantly in livers and hearts of retinol-depleted rats but not in brains, spleens and testes. Hearts contain less lipids and vitamin E than these latter organs, which could correlate with the highest production of MDA.

Animals↗
PubMed1990

[Immunosuppressive effect of cyclosporin A incapsulated into liposomes].

A preparation of cyclosporine A (CsA) in small liposomes (300 nm) was tested in a rat model of heterotopic cardiac allograft. At a daily dose of 1,5 mg/kg during 14 days, the graft survival rate was 30.4 +/- 2.8 days with a liposome-CsA solution versus 16 +/- 2.3 days with a Cremophore-CsA solution (p less than 0.01). Animals treated with the liposome-CsA preparation exhibited less weight loss than animals treated with cremophore-CsA solution (p less than 0.01). It is likely that the up-take of CsA by macrophages, when incapsulated into liposomes is dramatically enhanced; these cells have been pointed out at targets for IL2 inhibition by CsA.

Animals↗
PubMed1989

The action of free radicals on Deinococcus radiodurans carotenoids.

The possible role of carotenoids as free radical scavengers has not been completely elucidated. To gain further insight into the quenching of OH radicals by carotenoids, we used a feasible bacterial model, Deinococcus radiodurans, a red pigmented bacterium. We compared the action of H2O2 which produces in vivo OH radicals by a Fenton-type reaction on the parental and two mutant strains, i.e., a red pigmented and a colorless one. While the red pigmented bacteria were resistant to H2O2 action, the colorless strain was significantly more sensitive and its sensitivity was dose-dependent. In the red pigmented strains, H2O2 induced a significant decrease in one carotenoid (X5), which could be responsible for the antioxidant activity.

Carotenoids↗
PubMed1989

Polyacrylamide gradient gel electrophoresis of cytosolic retinol- and retinoic acid-binding proteins: application to rat testis and liver.

Distribution and cellular levels of retinol-binding protein and retinoic acid-binding protein, involved in the molecular action of retinoids, were analyzed in rat testis and liver. Both binding proteins of cytosolic extracts were separated by linear-polyacrylamide gradient gel electrophoresis and following electrophoretic separation, could be visualized by complementary identification tests such as autoradiography and marker proteins. The concentration of the binding proteins were evaluated by scanning the polyacrylamide gradient gels and the resulting data were found to be in accordance with those obtained by counting radioactivities. Polyacrylamide gradient gel electrophoresis appears suitable to detect and quantitatively evaluate cytosolic retinol- and retinoic acid-binding proteins.

Animals↗
PubMed1989

Absence of "A"-esterase activity in the serum of a patient with Tangier disease.

The levels of apolipoprotein A-I, A-II and B in subjects who are homozygous or heterozygous for Tangier disease are reported and compared with the amount of "A"-esterase in the serum. The "A"-esterases hydrolyse toxic organophosphate pesticides and are currently classified by the nomenclature committee of the International Union of Biochemistry as arylesterases (EC 3.1.1.2) although recent evidence has cast doubt on this classification. The apolipoprotein data are consistent with previous data reported for a number of Tangier patients. The homozygote has a marked reduction in apo A-I and A-II levels and a 30% reduction in apo B. The heterozygotes have about a 50% reduction of apo A-I, a slight reduction in apo A-II and no change in apo B. These apolipoprotein values correspond to a marked reduction in HDL cholesterol for the homozygote and substantial reductions in the heterozygotes. The "A"-esterase activity is zero in one homozygote while heterozygotes have about 5% of the levels in control subjects. Arylesterase activity appears to be essentially normal. The data thus support previous observations that the HDL "A"-esterase activity is greatly reduced in those conditions where HDL apo A-I is markedly reduced, e.g., in "Fish-eye" Disease.

Apolipoprotein A-I↗
PubMed1989

[Glucose and its protein environment in vivo].

The non-enzyme reaction by which glucose can combine with free amines has been known since the beginning of the century: in 1912, Mallard reported the combination of glucose with amino acids. This reaction results in the formation of cetoamine or fructosamine as well as often complex sub-products responsible for a change in the color of the medium that turns brown. This process, which food chemists are well-familiar with, was not observed in vivo until three-quarters of a century later. In 1975, hemoglobin A was shown to combine with glucose by means of a non-enzyme reaction, producing hemoglobin A1c. HbA1c is now believed to be a "black box", i.e. a cumulative reflection of all the hyperglycemic episodes that occurred over the last hundred days. This discovery was followed by an impressive number of similar observations: nearly all the available amines seem able to participate in this kind of reaction. Plasma proteins, membrane proteins, structural proteins such as collagen, the apolipoproteins of circulating lipoproteins, intracellular tubulines, and even nucleic acids seem capable of undergoing glycation. A great number of bioclinica uses of this phenomenon have already been developed. Diabetes mellitus has benefited most from these investigations and, from a broader viewpoint, studies in this field are unquestionably central to our understanding of atherosclerosis, inflammation, and cancer. Furthermore, the entire spectrum of these observations are related to ageing.

Apolipoproteins↗
PubMed1989

[Tissue effects of extracorporeal lithotripsy on a model of experimental biliary calculi in dogs].

Extracorporeal shock waves represent a new method to treat gallstones. This study was designed to evaluate: 1) the effectiveness of a recently available lithotripter (EDAP LT 01) for gallstone fragmentation; 2) adverse tissue reactions after treatment; 3) the optimum conditions for use of this apparatus in man. A human cholesterol stone was surgically implanted into the gallbladder of ten 20-25 kg mongrel dogs. One dog was used as a control. The other nine animals were divided into three groups (A, B and C). Two 60 min sessions of lithotripsy were carried out twice a week. Sonographic and CT examinations were performed 9 and 16 days after operation. The animals were killed 21 days after operation. Satisfactory fragmentation was obtained in 4 of the 9 animals, and in 2 dogs no stone fragments were detected. Fragments were found in the common bile duct in 5 dogs. In 2 animals a pathologic aspect of the papilla of Vater was observed. Marked hematoma was observed in the animals treated at 5 and 10 pulses/sec. In 5 cases, hematoma was observed in the gallbladder and in one case the gallbladder was ruptured. Hematoma was also noted in the hepatic vascular bed in 3 animals. Except for microscopic hemorrhagic lesions observed at the base of the right lung, no lesions were detected in any other organ. Shock waves produced by the EDAP LT 01 are effective for fragmentation of gallstones. However, in view of the tissue reactions observed at the higher pulse rates, the pulse rate should not exceed 2.5 pulses/s for use in man.

Animals↗
PubMed1989

[Treatment of vaso-occlusive crisis of sickle-cell disease with pentoxifylline].

Sickle-cell disease is usually complicated by vaso-occlusive attacks. A review of the case-histories of 26 patients permitted an analysis of 92 severe attacks. We compared the outcome of 52 attacks treated with hyperhydration associated with a modifying erythrocyte membrane agent (pentoxifylline), with 40 attacks treated with hyperhydration and other drugs. This result compares well the current knowledge of the rheologic mechanisms involved in vaso-occlusive attacks of sickle-cell disease.

Adolescent↗
PubMed1988

Modified lipid-protein interactions in Tangier beta lipoprotein (LDL2) demonstrated by fluorescence quenching.

Fluorescence quenching by iodide ions has been found to be higher in isolated Tangier low density lipoprotein (LDL2) than in isolated normal LDL2. Apolipoprotein (apo) B-100 is the main protein component of these lipoproteins and its tryptophanyl residues (Trp) are known to be the most hydrophobic and to be responsible for protein fluorescence. Trp exposure can thus be calculated; it was 0.50 in Tangier and 0.42 and 0.41 in insulin-dependent diabetics (IDD) and normal controls, respectively. The greater fluorescence quenching of Tangier LDL2 reveals a shallower embedding of Trp which is principally due to a lowered free cholesterol (FC) level in the shell and a smaller lipid core, itself dependent on a drop in cholesterol esters (CE). This is in accordance with the electrophoretic properties of Tangier LDL2 and suggests that Tangier LDL2 may be considered to be modified.

Adult↗
PubMed1987

Plasma apolipoproteins in Tangier disease, as studied with two-dimensional electrophoresis.

Tangier disease is characterized by a deficiency of high-density lipoproteins and of their major protein constituent, apolipoprotein (apo) A-I. We used high-resolution two-dimensional electrophoresis to examine the principal plasma apolipoproteins (A-I, A-II, A-IV, E, C-II, and C-III) of three persons with Tangier disease, one homozygous patient and his two heterozygous children, comparing the patterns with those for healthy subjects. Characteristic abnormalities were found in the distribution of the isoproteins of apo A-I, there being a normal concentration of pro apo A-I but dramatically decreased concentrations of the other apo A-I isoproteins. We also found hitherto-undescribed polypeptide abnormalities in apo C-III: sialylated and nonsialylated forms of apo C-III appear as double spots having the same isoelectric points but different molecular masses. No other substantial difference was detected in the polypeptide distribution of the other plasma apolipoproteins.

Adult↗
PubMed1987

Evaluation of lipoproteins and apolipoproteins in serum of a Tangier patient by micro-scale two-dimensional electrophoresis.

We examined lipoproteins and apolipoproteins in serum of a Tangier-disease patient. We used three different techniques of micro-scale two-dimensional electrophoresis: (a) no denaturants; (b) with sodium dodecyl sulfate (SDS) used only in the slab gel electrophoresis; (c) and with urea and a detergent used in isoelectric focusing and with SDS in slab gel electrophoresis. By technique a, an extremely low concentration of high-density lipoproteins (HDL) in the Tangier serum was seen, and lipoproteins that cannot form HDL complexes were detected as multiple spots in the acidic (pl 4 approximately 5) and relatively low apparent molecular mass (20,000 approximately 80,000) region. By technique b, Tangier low-molecular-mass lipoproteins were dissociated into their constituent apolipoproteins, and we observed a higher proportion of apoC-III, together with lower proportions of apoA-I and apoA-II, than in the normal HDL fraction. Technique c showed the total content of apolipoproteins in the whole Tangier serum, as several workers have reported. The presence of low-molecular-mass lipoproteins and a high concentration of apoC-III in this lipoprotein fraction characterized the Tangier serum.

Adult↗
PubMed1987

Ureaplasma-urealyticum-induced bladder stones in rats and their prevention by flurofamide and doxycycline.

Struvite calculi can be produced in the bladder of Sprague-Dawley male rats after injection of ureaplasmas into the renal medulla. Calculi appear 3 to 6 days after ureaplasma injection. We have studied the inhibitory effect of flurofamide, a potent inhibitor of Ureaplasma urealyticum urease, and doxycycline, on the formation of bladder stones. Flurofamide given orally in five doses (total 125 mg) over 3 days and doxycycline in seven doses (total 20 mg) over 4 days partially prevented stone formation only when given at the time of inoculation. Ureaplasmas disappeared rapidly from the urine. The inhibitory effect of flurofamide was higher than that of doxycycline. However, doxycycline seemed to be efficient when given for a long period (5 weeks).

Animals↗
PubMed1986

Preliminary report on a case of apolipoproteins CI and CII deficiency.

A combined deficiency of Apo C-I and C-II assessed by mono and bidimensional electrophoresis as well as immunoelectrophoresis is described. It was discovered after a 'check up' in a 70-yr-old woman consulting for a vertebral pain. Lipoprotein disorders correspond to a particular form of Fredrickson's type V. They consisted of types I and IV, with decreased HDL of low electrophoretic mobility, increased VLDL of high electrophoretic mobility, and without LDL. A decrease of Apo A-I, A-II, B and C-III was observed. Data correspond for the most part with all those actually known to characterize Apo C-II deficiency. HDL3 predominance in decreased HDL fraction and strongly decreased CE/TC ratio could be dependent of Apo C-I deficiency. The association of these two apolipoprotein deficiencies, the genes of which are located on chromosome 19, suggest a common defect on the pathway of their biosynthesis possibly located at the gene level. In spite of these numerous anomalies, the affection appears well tolerated.

Aged↗
PubMed1986

Immunochemical study of the plasma low and high density lipoproteins in Tangier disease.

Major disturbances of the lipoproteins in Tangier serum have been investigated using electrophoretic and immunochemical techniques. Previously described anomalies concerning the striking deficiency in HDL and the very low levels of apo A-I and apo A-II in Tangier patients are illustrated and explained. Anomalies concerning the fast LDL of Tangier serum are attributed to different forms of apo B not previously described. These data are strengthened by the features of a 2-dimensional electrophoresis method elaborated in the laboratory which allows apoproteins to separate in the second dimension. These apoproteins are obtained by the delipidation of the lipoproteins fractionated in a first polyacrylamide discontinuous gel. This method clearly shows the distribution of apoproteins in the first lipoprotein track and is in perfect accordance with the new concept of lipoprotein particles.

Apolipoprotein A-I↗
PubMed1986

Sp alpha I/65 hereditary elliptocytosis in North Africa.

The Sp alpha I/65 variant of the spectrin has been recently described in black people with hereditary elliptocytosis (HE). The present study reports on a similar Sp alpha I/65 variant in nine North African persons belonging to four unrelated families. The abnormality was associated with a variable degree of elliptocytosis. In one case, red cell morphology was normal. In the nine carriers of the biochemical abnormality, the spectrin dimer self-association was defective. The association constant was reduced: 0.65 to 1.7 X 10(5) M-1 (controls: 4.6 +/- 0.5 X 10(5) mM-1 (n = 21)); in six cases, there was a higher level of spectrin dimer in the low ionic strength extract at 4 degrees C: 13.0 to 19.7% (controls: 6.4 +/- 2.1% (n = 7)). Limited tryptic digests of spectrin from the nine persons revealed a decrease of the 80,000-dalton alpha-1 domain, and the concomitant appearance of a peptide with a molecular weight of 65,000 daltons and an isoelectric point ranging from 5.0 to 5.1. There was a correlation between the proportion of the 65,000-dalton fragments, the defect of spectrin self-association, and the extent of morphological alteration. This is the first large series concerning a spectrin abnormality in non-black persons. In North Africa, cases of HE that are not due to a protein 4.1 defect have turned out so far to be associated with the Sp alpha I/65 variant.

Algeria↗
PubMed1986

Ecology and arteriosclerosis.

An ecological theory of arteriosclerosis invokes antirisk factors dependent on infections and parasitic infestations through the medium of immunoglobulins. Dysglobulinemia modifies blood cholesterol, platelet function, hemostasis, and biophysics of the blood in the vessels. This could explain the differences in epidemiology of arteriosclerosis between northern developed countries and tropical countries, and the present frequency of coronary heart disease in developed countries. Arteriosclerosis is conditioned by environmental factors other than diet.

Arteriosclerosis↗