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Biomedical subjects

A Kahn

Publications and source records attributed to A Kahn.

At least 541 records · Page 30Linked to original sources
PubMed1979

Purification and partial characterization of different forms of phosphofructokinase in man.

Phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) from human muscle, brain, heart and granulocytes has been purified using a two or three step purification procedure. The main step is Blue Dextran-Sepharose 4B chromatography with selective elution of phosphofructokinase by formation of the ternary complex ADP or ATP-fructose-6-P-enzyme. Muscle and heart contain only enzyme subunits with a molecular weight of 85,000. This type of subunit is predominnant in brain, where it co-exists with subunits of about 80,000 daltons. A single type of subunits is found in the granulocytes, with a molecular weight of 80,000. Anti-muscle phosphofructokinase antiserum reacts only with M-type enzyme. Anti-granulocyte enzyme antiserum, absorbed by pure brain phosphofructokinase, exhibits a narrow specificity against the so-called L-type enzyme. Anti-brain antiserum, absorbed by pure muscle phosphofructokinase and partly purified red cell enzyme, exhibits a narrow specificity against a phosphofructokinase form predominant in fibroblasts and present in brain (F-type).

Brain↗
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

Significance of the electrophoretic modifications of defective pyruvate kinase variants. Study of six new observations.

Six new defective pyruvate kinase variants have been characterized in patients suffering from chronic hemolysis. Partially purified enzyme variants exhibited various anomalies from immunological, kinetic, stability and electrophoretic points of view. The significance of the electrophoretic anomalies has been interpreted in view of the normal post-synthetic maturation of the precursor enzyme L'4 into L2L'2 and L4, and the ability of trypsin to induce in vitro the transition L'4 leads to L4 has been tested. One defective enzyme existed in a single L'4 form and could not be transformed by trypsin into L4. In three cases slow-moving L'4 and L2L'2 forms were transformed by trypsin into an abnormal slow-moving L4 form. In the last two observations the L'4 and L2L'2 forms exhibited normal mobility and were normally transformed by trypsin into L4. The relevance of these data to the functional anomalies of the defective variants and to the nature of the primary genetic anomaly giving rise to the congenital defects in erythrocyte pyruvate kinase is discussed.

Anemia, Hemolytic, Congenital↗
PubMed1979

'GPI Roma', a new glucose phosphate isomerase deficient variant: in vivo occurrence of postsynthetic modifications of the mutant enzyme.

In a 5-year-old Italian girl with severe congenital hemolytic anemia, red cell GPI deficiency was proven, and found to be due to a new variant, 'GPI Roma.' The parents are first cousins and have been proven to be heterozygous for this variant. GPI Roma was slightly unstable to heat and exhibited a slightly increased Michaelis constant for fructose-6-phosphate. A single predominant fast-migrating GPI form existed in the patient's white blood cells, while the electrophoretic pattern in the red cells was composed, in addition to this 'fast band,' of a major band migrating as normal GPI and of an additional slow band. It is shown that this phenomenon may be ascribed to postsynthetic events modifying the charge of the mutant enzyme.

Anemia, Hemolytic, Congenital↗
PubMed1979

Controlled fall in natremia and risk of seizures in hypertonic dehydration.

The aim of the study was to derive some practical measurements which might help in defining a "safe" infusion rate in order to avoid seizures during treatment of hypernatremic dehydration. Forty seven infants with hypernatremic dehydration were rehydrated on a 160 ml/kg/24 h basis: 9 developed seizures during treatment (group I), 22 matched for age did not convulse (group II). Nine subsequent cases were prescribed a 120 ml/kg/24 h regimen: none convulsed (group III). The three groups were comparable in many respects, including initial plasma Na and pH. Fluids were comparable regarding (Na), their rates of administration were respectively 216, 181 and 123 ml/kg/24 h. The rate of infusion affected slopes of decreases in natremia. It was suggested that the decrease in plasma Na should not exceed 0,5 mEq/1/h.

Blood↗
PubMed1979

Tanglefoot syndrome.

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Education, Medical, Continuing↗
PubMed1979

Phosphofructokinase in human blood cells.

The subunit composition of phosphofructokinase from normal and malignant blood cells has been investigated by means of immunologic, electrophoretic, and chromatographic methods. Immunoprecipitation tests were performed with three specific antisera recognizing each of the basic subunits of human phosphofructokinase: muscle, M-type; liver, L-type; and fibroblast, F-type. Mature polymorphonuclear cells contain mainly L-subunits, while lymphocytes and platelets contain hybrids formed of L and F subunits; these hybrids can be electrophoretically separated. Red cell phosphofructokinase is composed of L and M subunits, as judged by its reactivity with anti-L and anti-M-type antisera. The various M-L hybrids composing red cell phosphofructokinase could be only separated by chromatography on DEAE-Cellulose. Lymphocytes from patients with chronic lymphocytic leukemia and lymphoblasts from patients with acute lymphoblastic leukemia contain phosphofructokinase forms similar to those from normal lymphocytes, while the immature granulocytic cells (leukemic myeloblasts and myeloid cells of chronic myeloid leukemia) are characterized by a reinforcement of enzyme inhibition by anti-F-type antiserum. Lymphoid lines in culture (Epstein-Barr virus (EBV)-induced or malignant lymphoma-derived lines) are characterized by the indistinctive expression of all three basic subunits, similar to that found in some fetal tissues. This article represents the first description of the isozymic nature of phosphofructokinase in platelets and white blood cells and of its changes with malignancy and cell culture. This enzyme might represent a useful marker in the characterization of the leukemic cells.

Antigens↗