Biomedical subjects

M Bernard

Publications and source records attributed to M Bernard.

At least 19 recordsLinked to original sources

PubMed1992

Patterns of alpha-L-fucosidase in acute myeloid leukemia cells. Comparison with promyelocytic HL-60 cell line.

Changes were observed in alpha-L-fucosidase forms in cells from acute myelocytic leukemias (AML). Total alpha-L-fucosidase activity was not significantly different for normal granulocytes and leukemic cells, but enzymic profiles obtained by chromatofocusing are quite different. In granulocyte profile, two main peaks are present (B and more acidic A) which were eluted at pH 5.2 with a shoulder at pH 4.6. In AMLs the B form is present but weakly expressed, whereas the more acidic forms are the major ones. This pattern may be related either to the malignancy character or to the stage at which the differentiation is stopped. Experiments on an HL-60 cell line (promyelocytic cells corresponding to the AML 3 type) showed that differentiation induced by dimethyl sulfoxide leads to the appearance of the B form present in normal mature cells. Thus the repartition of the enzyme forms seems to be related to the stage of differentiation of the myelocytic cells.

Acute Disease↗

PubMed1992

Molecular cloning and nucleotide sequence of a cDNA encoding hydroxyindole O-methyltransferase from chicken pineal gland.

Hydroxyindole O-methyltransferase (EC 2.1.1.4) is the enzyme that catalyses the synthesis of melatonin in the pineal gland and in the retina. Polyadenylated RNA from chicken pineal glands was used to prepare a cDNA library in lambda gt11. The library was screened with an antiserum directed against chicken hydroxyindole O-methyltransferase, and one cDNA clone was isolated. The fusion protein expressed by phage lysogens was identified on Western blots as a 165 kDA immunoreactive protein (beta-galactosidase, 110 kDa; hydroxyindole O-methyltransferase, 38 kDa). The fusion protein exhibited hydroxyindole O-methyltransferase activity. Its Km values for N-acetyl-5-hydroxytryptamine and S-adenosylmethionine were 5 times those of the natural enzyme. The intrinsic activity of the fusion protein was approx. 0.25% that of the natural enzyme. The cDNA consisted of 1436 nucleotides, including a 1038-nucleotide sequence encoding a full-length 346-amino-acid hydroxyindole O-methyltransferase. Comparison with bovine hydroxyindole O-methyltransferase [Ishida, Obinata & Deguchi (1987) J. Biol. Chem. 262, 2895-2899] revealed 52% identity in nucleotide sequences and 44% identity in peptide sequences. Northern-blot analysis revealed the presence of hydroxyindole O-methyltransferase mRNA transcripts in chicken pineal gland and retina, but not in the telencephalon.

Acetylserotonin O-Methyltransferase↗

PubMed1992

Dictyostelium discoideum as an expression host for the circumsporozoite protein of Plasmodium falciparum.

We have used the cellular slime mold, Dictyostelium discoideum (Dd), to express the Plasmodium falciparum circumsporozoite protein (CS), a potential component of a subunit vaccine against malaria. This was accomplished via an expression vector based on the discoidin I-encoding gene promoter, in which we linked a sequence coding for a Dd leader peptide to the almost complete CS coding region (pEDII-CS). CS production at both the mRNA and protein levels is induced by starving cells in a simple phosphate buffer. Variation in pH or cell density does not seem to influence CS synthesis. CS-producing cells can be grown either on their normal substrate, bacteria, or on a semi-synthetic media, without affecting CS accumulation level. The CS produced in Dd seems similar to the natural parasite protein as judged by its size and epitope recognition by a panel of monoclonal antibodies. We constructed a second expression vector in which the CS is under the control of a Dd ras promoter. CS accumulation can then be induced by external addition of cAMP. Such a tightly regulated promoter may allow expression of proteins potentially toxic to the cell. Thus, Dd could be a useful eukaryotic system to produce recombinant proteins, in particular from human or animal parasites like P. falciparum.

Amino Acid Sequence↗

PubMed1992

Long-term effects of constant light or darkness on chicken pineal hydroxyindole-O-methyltransferase expression: biochemical and cellular aspects.

1. Chickens kept in constant light, as opposed to constant darkness, display a twofold increase in the activity of pineal hydroxyindole-O-methyltransferase (HIOMT), the last acting enzyme in the melatonin pathway. 2. Using an immunological approach, we presently show that this regulation of HIOMT activity reflects changes in the concentration of a single molecular form of the enzyme protein (a 38 kDa polypeptide). Immunohistofluorescence indicates that these concentration changes concurrently affect modified photoreceptors and pinealocyte-like cells in the chicken pineal organ. 3. Together, the present data support the hypothesis that environmental lighting might regulate the expression of the HIOMT gene.

Acetylserotonin O-Methyltransferase↗

PubMed1992

Mammalian beta-D-mannosidase and beta-mannosidosis.

Lysosomal beta-D-mannosidase is the last exoglycosidase involved in the sequential degradation of the N-glycosylproteins glycans. Research on this enzyme was restricted before the discovery of its hereditary deficiency, first in goat (1981) and later in man (1986). We describe the biochemical aspects of these beta-mannosidosis and the properties of the beta-mannosidases of mammalian origin. Our own results concerning human enzyme (from kidney and urine, seminal plasma and blood cells) suggest that, apart from the case of the inherited disease, beta-mannosidase may become a useful tool in other pathologies.

Animals↗

PubMed1992

[Volar plate osteosynthesis in typical and atypical distal radius fractures].

28 patients with a fracture of the distal end of the radius were treated by a T-plate osteosynthesis through the volar approach. There were 7 unstable distal metaphyseal fractures and 21 dislocated intra-articular fractures. 21 patients were investigated 6 months to 8 years after operation according to the scheme of Sarmiento. 17 patients had a good or excellent result, 4 patients a fair or poor result. 2 patients developed a Sudeck's dystrophy (Algodystrophy), one of them with a radial-ulnar bone bridge. The volar application of the plate is indicated for flexion and extension fractures. In cases with compression of the dorsal cortex a bone graft is indicated to improve a stable osteosynthesis. A conventional tomography on two views helps to diagnose exactly an intra-articular fracture and to decide whether to use a plate or pins and external fixation after open reduction. Remanipulation or an operation 2 weeks after trauma increases the risk of a Sudeck's dystrophy and leads to a poor result.

Adult↗

PubMed1992

[Magnetic resonance tomographic diagnosis of internal lesions of the shoulder following luxation. A comparison with arthroscopic findings].

Fifteen patients with a recurrent dislocation of the glenohumeral joint were preoperatively investigated by MRI. We created a special protocol with axial T1-, T2-, proton-density- and sagittal T1-weighted images. MRI findings such as defects of the glenoid labrum and Hill-Sachs compression fractures proved to be correct during surgery. In the chosen protocol the diagnostic imaging of rotator cuff lesions was not specific. In 10 cases lesions were seen but in only 5 patients did these findings prove to be correct during surgery. However, MRI imaging of glenohumeral joints is a reliable non-invasive diagnostic method.

Adult↗

PubMed1991

Isolation from mouse fibroblasts of a cDNA encoding a new form of the fibroblast growth factor receptor (flg).

Structural definition of the receptors for neurotropic and angiogenic modulators such as fibroblast growth factors and related polypeptides will yield insight into the mechanisms that control early development, embryogenesis, organogenesis, wound repair and neovessel formation. We isolated 3 murine cDNAs encoding different binding domains of these receptors (flg). Comparison of these ectoplasmic portions showed that two of the forms corresponded to previously described murine molecules whereas the third one had a different ectoplasmic portion generated by specific changes in two regions. Interestingly, expression of this third form seems to be restricted in its tissue distribution. Such modifications could influence the ligand specificity of the different receptors and/or their binding affinity.

Amino Acid Sequence↗

PubMed1991

Molecular and cellular aspects of hydroxyindole-O-methyltransferase expression in the developing chick pineal gland.

The pineal gland influences circadian activity and seasonal breeding through the production of an indolic hormone, melatonin. The terminal step of melatonin biosynthesis is catalyzed by hydroxyindole-O-methyltransferase (HIOMT). Using an antibody directed against HIOMT, we examined the differentiation of the melatoninergic phenotype in the developing chick pineal gland. HIOMT first appeared 4 days before hatch and rose linearly until the 7th day posthatch. This was correlated with an increased immunoreactivity of the 38 kDa enzyme on Western blots and with an accelerated rate of HIOMT biosynthesis as demonstrated by [35S]methionine labeling. Immunocytochemistry revealed a growing number of HIOMT-positive cells between day 2 before hatch and day 15 posthatch. Until hatching HIOMT was expressed almost exclusively in modified photoreceptors. Parafollicular pinealocytes became HIOMT-positive mostly after hatching. Their different timings of functional differentiation emphasize the existence of two populations of melatonin-producing cells in the chick pineal gland.

Acetylserotonin O-Methyltransferase↗

PubMed1991

Expression of nuclear matrix proteins in rat liver tissue.

We have studied the synthesis of nuclear matrix proteins as it occurs in the rat liver. To investigate their kinetics in tissue, nuclear matrix proteins were prepared from liver of rats injected with radioactive methionine. Synthesis of lamins was not observed in quiescent hepatocytes although they were the principal proteins of this subcellular fraction, suggesting that lamins are very stable in the liver. When hepatocytes were stimulated to divide by partial hepatectomy, only synthesis of lamin B was initiated. Many proteins not visible on Coomassie blue-stained gels were detectable by autoradiography. In the nuclear matrix extracts of quiescent hepatocytes, one of the most prominently labeled ones was a protein of 70 kDa. After hepatectomy, an additional protein of 62 kDa was detectable. These proteins were visible 1 h after the injection of radioactivity, but were no longer observed in nuclear matrices prepared 24 h after injection. These experiments indicate that in addition to lamins, two nuclear matrix proteins are present in the rat liver that were not detected previously, perhaps because of their rapid turnover.

Animals↗

PubMed1991

Evaluation of somatic cell variants deficient in glycosylphosphatidyl-inositol anchoring as candidates for genetic correction.

Many cell surface glycoproteins are anchored in the lipid bilayer by a glycosylphosphatidyl-inositol (GPI) structure. Recently, a number of cell lines which are deficient in the biosynthesis and/or addition of this anchor have been described. In this report, we summarize the current knowledge on these lines and discuss their potential use to isolate the genes involved in the GPI anchor biosynthetic pathway with a specific emphasis on L cell fibroblasts.

Animals↗

PubMed1991

Hydrodynamic and energetic aspects of exogenous free fatty acid perfusion in the isolated rat heart during high flow anoxia and reoxygenation: a 31P magnetic resonance study.

STUDY OBJECTIVE: The aim was to show differences between the effects of various dietary long chain fatty acids (palmitic, oleic, linoleic, alpha and gamma linolenic acids) perfused in isolated rat hearts subjected to a sequence of high flow anoxia and subsequent reoxygenation. DESIGN: Isolated working rat hearts perfused with selected exogenous fatty acids were allowed an initial 30 min equilibration period followed by 60 min of high flow anoxia and 40 min of reoxygenation. Ventricular function and tissue contents of phosphorylated metabolites were monitored concomitantly using standard procedures and 31P magnetic resonance spectroscopy respectively. EXPERIMENTAL MATERIAL: Hearts were removed from male Wistar rats weighing 350-400 g. Results from eight hearts were pooled for each of the five fatty acids perfused. MEASUREMENTS AND MAIN RESULTS: High coronary flow maintained during anoxia led to an increased extracellular washout of lactate and only to mild intracellular acidosis, limiting myocardial damage by metabolites of anaerobic glycolysis. Under these conditions, marked differences between the classes of perfused fatty acids were observed. Hearts which received oleic acid showed the most depressed ventricular function and a greater depletion in high energy phosphates content. These deleterious effects were completely reversed by the separate administration of two fatty acid metabolism blocking agents, nicotinic acid and oxfenicine. Cardioprotection was enhanced by perfusion of polyunsaturated fatty acids (linoleic acid, alpha and gamma linolenic acids). Hearts perfused either with glucose or with palmitic acid behaved similarly and showed an intermediate functional and metabolic postanoxic recovery. CONCLUSION: This study documents the relation between the chemical structure of exogenous fatty acids used in heart perfusion and their ability to improve or impair postanoxic myocardial recovery. The cardioprotective effect of polyunsaturated fatty acids was documented by simultaneous evaluation of mechanical performance and metabolic response.

Animals↗

PubMed1991

[The malunited juvenile fracture--Monteggia defect].

Late reconstruction after neglected Monteggia lesions in children is discussed. On the basis of the literature (20 cases) and 2 personal cases it is deduced that open reduction of the radial head should be combined with osteotomy of the ulna according to the pathophysiology of the lesion. Details of the operative procedure are given. Reconstruction of the annular ligament is the least important part. Reconstruction is indicated in children under the age of 10-12 years even if the dislocation has been present for years. Unfavorable conditions for operative reconstruction are long-lasting dislocations in older children, deformation of the radial head, and imminent skeletal maturity.

Adolescent↗

PubMed1991

[Alpha-L-fucosidase of normal and pathological blood cells].

The glycosidases, enzymes which participate in the degradation of glycoproteins and glycolipids inside the lysosomes are themselves glycoproteins and, for one enzyme, several forms may be isolated in tissues and in biological fluids, corresponding to variations in the composition or the structure of their glycanic moiety. We have previously studied the different forms of alpha-L-fucosidase in human serum, kidney and urine. Some modifications of the glycanic fraction of glycoproteins have been described in various forms of tumoral cells; therefore, we have attempted to verify if the alpha-L-fucosidase of blood cells might be a useful marker in the diagnosis of leukemias, using the enzymic pattern obtained by chromatographic or electrofocusing methods. Detergent extracts from normal lymphocytes, submitted to ion-exchange chromatography as well as to chromatofocusing, revealed the presence of two forms of alpha-L-fucosidase, A and B, with respective pIs of 5.7 and 6.2. After treatment by neuraminidase, these two forms remain distinct, showing that the degrees of sialylation is not the only difference. Moreover, after desialylation, the two forms have not the same affinity for concanavalin A, an argument for the heterogeneity of the glycanic structures. The determination of the total activity, and of enzymic patterns of alpha-L-fucosidase from leukemic cells led to the observation of three types of modifications, in comparison with normal lymphocytes: quantitative variations in the total activity; variations in the proportions of the two forms; variations due to the modification of pIs. We have studied the lymphocytes from four patients with a hairy-cell leukemia (HCL), four patients with chronic lymphoid leukemia (CLL) and the MO cell-line, proceeding from a HCL. In all cases, the total fucosidase activity is strongly decreased in comparison with normal lymphocytes activity. The chromatofocusing pattern for CLL cells reveals the presence of the A and B forms, without modification of their eluting pH. A characteristic pattern is obtained with hairy cells, presenting only the B form, eluted in more acidic conditions. The normal lymphocytes in peripheral blood are for 80 per cent of the T phenotype, and the CLL lymphocytes exhibit the phenotypic markers B, as well as the hairy cells, but the MO cell-line acquires in culture the T markers. As these last cells express both the A and B forms of enzyme, the absence of the A form of alpha-L-fucosidase seems to be a marker of the HCL.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomarkers↗

PubMed1990

Application of reverse-DEPT polarization transfer pulse sequence to study the metabolism of carbon-13-labeled substrates in perfused organs by 1H NMR spectroscopy.

Metabolism of 13C-enriched metabolites can be advantageously studied by reverse-polarization transfer methods. In this work an improved reverse-DEPT sequence has been applied for the first time on perfused organs in a 20-mm probe. The metabolic fate of 99% enriched [2-13C]acetate perfused in excised rat liver and heart has been documented.

Acetates↗

PubMed1990

Human urinary and renal alpha-L-fucosidases. A comparative study.

1. Enzymatic forms of alpha-L-fucosidase from human renal tissue and urine were investigated. 2. In renal tissue two different isoenzymatic patterns were obtained by chromatofocusing of either directly soluble or detergent solubilized extracts. 3. On the other hand the urinary isoenzymatic pattern is similar to that obtained for the renal soluble extract.

Adult↗

PubMed1990

Umbilical cord blood gases for term healthy newborns.

Examination of paired umbilical arterial and umbilical venous blood gases for 147 term, healthy newborns revealed a strong correlation of pH, bicarbonate, and base excess with the 1-minute Apgar score. Although significantly different from each other, a strong correlation existed between the gas measurements of the two vessels. The lower limit of pH for the umbilical artery was 7.12 and for the vein, 7.25. The arterial-venous difference for bicarbonate but not pH, oxygen or carbon dioxide tension, or base excess was correlated with the 1-minute Apgar score.

Apgar Score↗

PubMed1990

Intracellular pH and role of Na+/H+ exchange during ischaemia and reperfusion of normal and diabetic rat hearts.

STUDY OBJECTIVE: The aim was to investigate the role of intracellular pH (pHi) and ion exchange on the functional recovery of perfused hearts isolated from normal (N) rats either receiving or not receiving amiloride (an Na+/H+ exchange inhibitor), and from STZ induced diabetic (D) rats with decreased Na+/H+ exchange activity. DESIGN: Working heart preparations were submitted to a zero flow ischaemic period of 30 min at 37 degrees C and then reperfused for 30 min. The time course of pHi decline during ischaemia and of recovery on reperfusion was followed by means of 31P-NMR. MEASUREMENTS AND MAIN RESULTS: In N hearts without amiloride, ischaemia caused a progressive decrease in pHi. This was slightly, although not significantly, more abrupt in N hearts receiving amiloride. D hearts showed a slower fall in pHi, but the mean value reached after 30 min did not differ significantly from that of normal hearts. pHi recovery on reperfusion was markedly slower in the D hearts compared to N hearts. The mean value reached after 30 min did not differ significantly from that of N hearts. pHi recovery was also markedly slower in N hearts exposed to amiloride during both ischaemia and reperfusion. The higher functional recovery on reperfusion, as assessed by the recoveries of aortic flow and stroke volume, was observed for those hearts with slower pHi recovery. Improved recoveries of aortic flow and stroke volume as compared to normal non-treated hearts were 34% and 21% for the diabetic hearts, and 22% and 40% for the normal hearts receiving amiloride. CONCLUSIONS: The comparison of data from diabetic rat hearts with reduced activity of the Na+/H+ exchange process v normal hearts with pharmacological block of the exchanger provide support for a critical role of the Na+/H+ exchanger in the initial stage of reperfusion.

Amiloride↗