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Biomedical subjects

J C Dreyfus

Publications and source records attributed to J C Dreyfus.

At least 55 records · Page 3Linked to original sources
PubMed1981

Muscle phosphofructokinase deficiency in man: expression of the defect in blood cells and cultured fibroblasts.

Using specific immunoprecipitation of M-type phosphofructokinase and assay of immunoprecipitate enzyme activity, it was possible to detect some M-type enzyme in normal blood cells and fibroblasts, although this isoenzyme represents a very small part of total phosphofructokinase. White blood cells and cultured fibroblasts from a patient with hereditary muscle phosphofructokinase deficiency showed normal phosphofructokinase activity and electrophoretic pattern; direct immunoneutralization results were also normal. Nevertheless, it was possible to prove the defect in these cells using the immunoprecipitation method: no active immunoprecipitates could be obtained with anti M-type antibody. The patient's red blood cells had a reduced phosphofructokinase activity which was only neutralized by anti L-type antiserum. The purification of partially deficient red cell phosphofructokinase confirmed that this enzyme only consisted of L-type subunits while, under normal conditions, both L- and M-type subunits are observed. The possibility of detecting specific enzyme defects in apparently non-affected cells could be of practical importance, especially in prenatal diagnosis.

Adult↗
PubMed1981

Research on molecular mechanisms of McArdle's disease (muscle glycogen phosphorylase deficiency). Use of new protein mapping and immunological techniques.

McArdle's disease is due to the lack of activity of muscle glycogen phosphorylase. We investigated the presence of an inactive protein by two techniques: (a) Bidimensional protein maps, using a modification of the original O'Farrell technique allowing location of phosphorylase. (b) Purification of enzyme from crude muscle extracts, using an immunoaffinity microchromatographic procedure. Protein maps of three patients were obtained. No protein was detected at the normal (97 K) position of phosphorylase but 70 and 60 K spots were visible. Results of enzyme purificaton by immunoaffinity were negative for one patient, whereas a small band of phosphorylase-like material was detected in the other. Our results confirm the molecular heterogeneity of the disease. We think such methods might be useful for investigating other genetic diseases.

Adolescent↗
PubMed1980

PK3: a new chromosome enzyme marker for gene dosage studies in chromosome 15 imbalance.

Gene dosage studies yielded results consistent with the assignment of the locus for pyruvate kinase (PK3) to chromosome 15. The activity of seven cytoplasmic enzymes has been determined in fibroblast extracts from six trisomy 15 lines and 16 normal control lines. The fibroblast extracts from the trisomic patients had pyruvate kinase activity 57% higher than fibroblast extracts from control lines, while other enzyme activities were within the normal range of activity.

Alleles↗
PubMed1980

White blood cells and the diagnosis of alpha-glucosidase deficiency.

Leukocytes were obtained from 14 healthy subjects, one patient with the infantile form, two patients with the adult variant of acid maltase deficiency, two patients with chronic myelocytic leukemia, two patients with acute myeloid leukemia, and two patients with chronic lymphotic leukemia. In addition, lymphocytes were prepared from three normal subjects, and five established lymphoid lines were used. Cells were extracted either with Triton 0, 2%, or with water followed by 0.2% Triton. alpha-Glucosidase activity was measured in water homogenates, water extracts after centrifugation, and Triton extracts, with or without antisera directed against acid maltase (EC 3.2.1.3) and renal maltase (EC 3.2.1.20). The percentage of acid and renal maltases was then calculated in each soluble fraction. Normal whole leukocytes (mostly granulocytes) contain both acid and "renal" maltases, whereas normal lymphocytes contain very little or no "renal maltase." This isozyme is present in chronic myelocytic leukemia, but is absent in acute myeloid and chronic lymphocytic leukemia as well as in established lymphoid lines. Acid maltase is almost completely extracted with water, whereas renal maltase is extracted only with Triton. From the results, it appears that for the diagnosis of alpha glucosidase deficiency, cells should be extracted in water and centrifuged before determination. Lymphocytes, which are devoid of renal maltase, are a better diagnostic material than are granulocytes.

Glucan 1,4-alpha-Glucosidase↗
PubMed1980

Phosphofructokinase in human fetus.

The isozymic composition of phosphofructokinase (EC.2.7.1.11) from human fetal tissues has been investigated by immunological characterization, electrophoresis, purification, and SDS-polyacrylamide gel electrophoresis of the dissociated subunits. One of the characteristics of fetal tissues is the indiscriminate expression by all the cells of two or three of the basic forms of phosphofructokinase without any isozyme really corresponding to a specifically fetal form. In particular, L-type enzyme, identical to the highly regulatory enzyme synthesized by the adult hepatocytes, is found in most fetal tissues, especially in muscle and brain. M-type subunits are also detected in most of the organs and constitute the major form in fetal muscle and adrenals. F-type subunits are predominant in fetal stomach and yolk sac and are practically the only form in fetal heart. Some electrophoretic and chromatographic differences between fetal and adult M-type phosphofructokinase exist; whether their nature is genetic or posttraductional is so far unknown. Some differences (of molecular weight and chromatographic properties) are also detected between the fetal L-type subunits and enzyme from adult granulocytes. A mild proteolytic attack of the former by subtilisin transforms it into an enzyme form indistinguishable from granulocyte phosphofructokinase.

Adrenal Glands↗
PubMed1980

Residual mannosidase activity in human mannosidosis: characterization of the mutant enzyme.

The prenatal diagnosis of affected fetuses in two families at risk for mannosidosis gave us the opportunity to study the residual alpha-mannosidase activity. We found an altered acidic alpha-mannosidase characterized by lowered affinity toward the substrate, displacement of maximal activity toward pH 4-5, thermal lability, different migration in electrophoresis, and apparent change in molecular weight at alkaline pHs. The immunological properties seem unchanged since the enzyme was precipitated by an antiacidic alpha-mannosidase antiserum. The mutant enzyme instability, provoked by dialysis, and its reactivation after addition of dialysis fluid, suggests an association-dissociation phenomenon. We propose a possible hypothesis that a low molecular weight ligand is necessary to maintain the activity of the mutant enzyme.

Centrifugation, Density Gradient↗
PubMed1980

Lysosomal hydrolases in established lymphoid cell lines.

The activity of lysosomal acid hydrolases was determined in five established lymphoid lines. Of four B cell lines three contained the EBV genome, and one was an EBV free Burkitt derived lymphoma line. The fifth was derived from acute lymphoblastic leukaemia expressing T cell characteristics. Ten enzymes were assayed in extracts from each cell line. Wide dispersions have been observed between the five lines. The activity level of most enzymes was lower in lymphoid lines than in leukocytes or fibroblasts, and in lines derived from pathological cells from normal cells.

Cell Line↗
PubMed1979

Phosphofructokinase (PFK) isozymes in man. I. Studies of adult human tissues.

Isozymic heterogeneity of human phosphofructokinase was investigated by means of ATP inhibition, immunoneutralization by antihuman muscle-type and antiliver-type phosphofructokinase antisera, solubility in (NH4)2SO4 solutions, and starch gel and polyacrylamide slab gel electrophoresis. The enzymes studied by these methods were purified from various normal and malignant human adult tissues by chromatography on blue Dextran Sepharose 4 B columns. From the results of these studied we suggest that three basic phosphofructokinase isozymes could exist: muscle-type, fibroblast-type, and liver-type isozymes. Muscle-type isozyme is the single form found in adult muscle, and is involved in the enzymes from heart, brain, red cell, and testis. Fibroblast-type isozyme is found mainly in the placenta, fibroblasts kidney, and some malignant tissues. Liver-type phosphofructokinase seems to be very definitely the predominant form in mature polymorphonuclear cells, platelets, and liver. Testis and red cell phosphofructokinase enzymes definitely include msucle-type aand liver-type subunits, associated in various hybrid forms.

Electrophoresis↗
PubMed1979

Alpha-mannosidase in human red cells.

1. A search for lysosomal hydrolases and related enzymes has been made in hemolysates from human and rabbit red cells. Apart from acid phosphatases, significant activities were found only for alpha-mannosidase, neutral alpha-glucosidase and beta-hexosaminidase. 2. alpha-Mannosidase (alpha-D-mannoside mannohydrolase, EC 3.2.1.24) activity per cell in human red blood cells was 200-times lower than in white cells. The optimal pH was 5.5--6.0. Electrophoresis on cellulose acetate showed three bands. Hemolysates from four patients with mannosidosis were not deficient in alpha-mannosidase. pH activity curves and elctrophoretic pattern were similar to those of controls. From its biochemical and genetic properties, it is concluded that red cell mannosidase differs from the lysosomal acid mannosidase.

Animals↗
PubMed1979

Modifications of aldolase during in vivo aging of rabbit red cells.

Crude hemolysates, partially purified aldolase and aldolase purified to homogeneity from reticulocytes and mature erythrocytes, were incubated with a specific antiserum raised against crystalline rabbit muscle aldolase. We show that the same aldolasic activity corresponds to a greater amount of antigen in older than in younger cells, in crude hemolysates as well as in the above mentioned preparations; that is to say, old-cell aldolase contains cross-reacting material (CRM). Properties of purified enzyme from reticulocytes and mature erythrocytes were compared to those of muscle crystalline aldolase: -- the molecular specific activity of purified aldolase from erythrocytes is lower than with crystalline muscle aldolase, i.e. CRM is maintained throughout the purification steps. -- the specific activity of red cell aldolase towards both substrates (FDP and F1P) is lower than that of crystalline muscle aldolase. However, the ratio of activity towards the two substrates FDP/F1P is decreased in erythrocytes and reticulocytes. -- no other difference was found: Michaelis constant towards FDP, thermodenaturation constant and C terminal extremities are identical as are the molecular weights.

Amino Acids↗
PubMed1979

Antenatal diagnosis in three pregnancies at risk for mannosidosis.

Three pregnancies were monitored in two families at risk for mannosidosis, alpha mannosidase and alpha fucosidase were determined on extracts from white blood cells of several members of these families, on fibroblast cell lines from the index cases and on uncultured and cultured amniotic cells of the foetuses. Two foetuses were diagnosed as affected and one as being free from the disease. The conclusions were confirmed on the affected foetuses after interruption of the pregnancy. The noticeable residual activity of alpha mannosidase found in some fibroblasts and cultured amniotic cells required complementary investigations (heat lability and dependency of substrate concentration) to reach a reliable diagnosis. Invesitgation of uncultured amniotic cells may give useful additional information.

Abortion, Induced↗