[Acute barbiturate poisoning].
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Acute Disease↗
Biomedical subjects
A Kahn
Publications and source records attributed to A Kahn.
[Mechanism of decrease in erythrocyte enzyme activities during red cell aging in the newborn and the adult].
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Erythrocyte Aging↗
Studies on the nature of different molecular forms of glucose-6-phosphate dehydrogenase purified from human leukocytes.
Several molecular forms of human glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) corresponding to different stages of post-synthetic modifications have been purified from human leukocytes. The various enzyme forms were different in their specific activity, their kinetic properties and their isoelectrofusing pattern. The molecular weight of the subunits of the different forms was not modified. The changes in the electrofocusing pattern were not due to modifications of the N-terminal ends, the oxidation of thiol groups or the non-covalent fixation of an acid molecule upon the enzyme. Carboxypeptidase B cleaved a C-terminal lysine from the different enzyme forms and shifted the isoelectric point of the different enzyme active bands towards the acid pH. The different enzyme forms studied here seemed to result from the action upon 'native glucose-6-phosphate dehydrogenase' of 'modifying factors' especially abundant in some leukemic granulocytes. The modifying factors did not seem to be consumed during the 'modification' of glucose-6-phosphate dehydrogenase. Moreover, the storage for one year of unmodified enzyme resulted in changes in its electrofocusing pattern similar to those quickly induced by the 'modifying factors'. Consequently it appears that the modifying factors are catalysts of the modification of special residues of glucose-6-phosphate dehydrogenase. The hypothesis that this modification involves the deamination of asparagine or glutamine residues is put forward.
Amino Acid Sequence↗
Mechanisms of the acquired erythrocyte enzyme deficiencies in blood diseases.
Acquired enzymatic activity defects of erythrocyte pyruvate kinase, glucose phosphate isomerase and phosphofructokinase have been studied in patients with acute myeloid leukemias, sideroblastic refractory anemias and unclassified acquired dyserythropoiesis. 6 patients with acute myeloid leukemia had a lowered erythrocyte pyruvate kinase activity; in 5 of them the concentration of the "pyruvate kinase"-antigen was parallely decreased, in such a manner that the ratio enzyme activity/immunologic reactivity (i.e. the molecular specific activity) was normal. In 1 patient with acute leukemia, 4 with refractory anemia and 1 with acquired dyserythropoiesis the defect of the pyruvate kinase activity was associated with a normal antigen concentration (and, therefore, the molecular specific activity in whole hemolysate was lowered). The enzyme activity was restored by incubation with SH reagents in two cases and by partial purification as often as it was performed. The electrofocusing pattern of erythrocyte pyruvate kinase was normal in both these types of defects. In two patients with so-called "acquired dyserythropoiesis" an erythrocyte glucose phosphate isomerase deficiency has been detected; in both the cases it was associated with a parallel decrease of the antigen concentration. The residual enzyme had a normal electrofocusing and electrophoretic pattern and a normal heat stability; the enzyme activity could not be restored by any treatment. In 1 patient with erythroleukemia and in 1 other with acquired dyserythropoiesis the erythrocyte phosphofructokinase activity was lowered. The enzyme activity was not restored by cross incubation in isologous plasma or by the SH reagents. In one case immunologic study could be performed, indicating that the enzyme defect was mainly due to the decreased ratio of the muscle type subunit of the erythrocyte phosphofructokinase. The electrofocusing pattern of deficient phosphofructokinases was normal. Finally, we point out the probable existence of several direct mechanisms, genetic and post translational, accounting for the acquired enzyme defects of red blood cells in various blood disorders.
Anemia, Hemolytic, Congenital Nonspherocytic↗
Antinuclear antibodies in patients on lithium carbonate.
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Adult↗
L-type pyruvate kinase from human liver. Purification by double affinity elution, electrofocusing and immunological studies.
L-type pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) was highly purified from adult human liver. This purification included ammonium sulphate fractionation, DEAE-Sephadex batchwise absorption and two CM-Sephadex chromatographies with selective elution by ligands; in the former chromatography pyruvate kinase was eluted by ATP, in the latter one by phosphoenolpyruvate and fructose 1,6-diphosphate. The last step of the purification procedure involved a hydroxyapatite column chromatography. This purification procedure allowed us to obtain 3.6 mg of protein with a specific activity 190 I.U./mg, i.e. a 1200-fold purification with an overall yield of about 8%. This preparation was homogenous as judged by immunodiffusion, acrylamide and sodium dodecyl sulphate acrylamide gel electrophoresis. Anti L-type pyruvate kinase antibodies were obtained from rabbits and the antigenic properties of L-type pyruvate kinase were studied. The enzyme appeared to be a tetramer (molecular weight 220 000-240 000) with subunits of similar molecular weight about 60 000). Two interconvertible major forms were found by isoelectrofocusing in a sucrose gradient and in an acrylamide slab gel: one had an isoelectric point of 5.85 +/- 0.09 and was the major enzymatic form after incubation with fructose 1,6-diphosphate or high concentrations or SH reagents. The other form (isoelectric point 6.28 +/- 0.03) was the major form of L-type pyruvate kinase in liver crude extract, and after incubation of purified enzyme with a proteic fraction isolated from liver extract by ammonium sulphate precipitation.
Chromatography, Affinity↗
Pyruvate kinase isozymes in man. II. L type and erythrocyte-type isozymes. Electrofocusing and immunologic studies.
By focusing in sucrose, gradient L-type pyruvate kinase from human liver could be separated into 2 major forms (pI 6.28 +/- 0.03 and 5.85 +/- 0.09) and a minor more acid form (pI = 5). These different forms could also be detected by focusing in acrylamide-ampholine slab gel. The major forms were interconvertible, the equilibrium being shifted toward the acid form by fructose 1,6-diphosphate and SH reagents, and toward the alkaline form by proteinic factors extracted by ammonium sulphate fractionation from liver extracts and from hemolysates. These factors seemed to be responsible for the stabilization of the liver crude extract enzyme in its alkaline conformation. By acrylamide slab gel electrofocusing, erythrocyte pyruvate kinase from whole hemolysates exhibited a complex pattern composed of at least 3 introconvertible forms. The in vitro aging of the red blood cells and the storage of the hemolysates resulted in a progressive disappearance of the acid forms and in a strengthening of the alkaline form. Partially purified erythrocyte enzyme focused in 2 major bands, interconvertible under the influence of the same factors as those described for L-type pyruvate kinase. Although closely related, the focusing patterns of L-type and erythrocyte-type were never exactly identical. Double immunodiffusion against antihuman erythrocyte-and L-type pyruvate kinases. Moreover, antihuman M2-type serum was unable to neutralize erythrocyte pyruvate kinase as well as to change its electrophoretic mobility. Consequently, we conclude that both human erythrocyte- and liver L-type pyruvate kinases existed under several conformers interconvertible under the influence of the same ligands or proteinic factors; erythrocyte-type enzyme seems to include L-type subunit and not M1- or M2-type subunits. The erythrocyte- and L-type enzymes, however, are not identical and the nature of the differences between them is discussed.
Cross Reactions↗
GD (--) Aachen, a new variant of deficient glucose-6-phosphate dehydrogenase. Clinical, genetic, biochemical aspects.
A deficient G-6PD variant was discovered in 4 males of one family from northwestern Germany. Five generations of this family could be studied. The deficient G-6PD was a new variant, called "Gd (--) Aachen". Its main characteristics are the following: severe enzyme deficiency in erythrocytes (3% of normal), contrasting with an almost normal activity in leukocytes; normal molecular specific activity (i.e., normal ratio enzyme activity/cross-reacting material); slow mobility in starch gel electrophoresis (92-94% of normal); increased Michaelis constant for glucoes-6-phosphate (60-70 muM) and NADP+ (20-25 muM); decreased inhibition constant by NADPH with respect to NADP+ (7 muM); increased inhibition by ATP; normal utilization of the substrate analogues; slightly biphasic pH curve; thermal instability, and normal activation energy of the enzymatic reaction. The relationships between the hematologic disorders (severe and frequent hemolytic crises) and the unfavorable kinetic modifications are discussed.
Adult↗
Human erythrocyte phosphoglycerate kinase deficiency: presence in a deficient patient of a stable variant with lowered catalytic activity.
The phosphoglycerate kinase deficiency found in one boy with hemolytic anemia was associated with an almost normal concentration of phosphoglycerate kinase-immunologically related material in the patient's erythrocytes. Consequently the catalytic activity of the mutant enzyme was drastically lowered. Besides, the abnormal phosphoglycerate kinase was more stable to heat and to urea than normal phosphoglycerate kinase and its isoelectric point was slightly increased.
Adult↗
[Contribution of the "limulus test" to the diagnosis of endotoxemias and meningitis due to gram negative bacteria].
The "limulus test" may be used to detect the endotoxins of Gram negative organisms. Applied to the cerebrospinal fluid (79 specimens from 64 patients) it proved itself to be a very important contribution to the differential diagnosis of purulent meningitis (95% positive results, no false positives). However it can be used on the plasma only in patients with shock of suspected endotoxic origin.
Adult↗
Pyruvate kinase isozymes in man. I. M type isozymes in adult and foetal tissues, electrofocusing and immunological studies.
Anti human M2 type and anti human L type pyruvate kinase sera allowed us to distinguish two groups of pyruvate kinase in man. Erythrocyte and liver (L type) enzymes on the one hand were inhibited by anti L and not all by anti M2 serum; pyruvate kinase from all the other tissues on the other hand were inhibited by anti M2 and not at all by anti L serum. This latter group represent the M type pyruvate kinase isozymes. The M type isozymes have been studied by electrofocusing in thin layer acrylamide-ampholine gel. In adult tissues 4 types of isozymes were found, designated, from acid to alkaline pH, as M2 (predominant form in spleen, leukocytes, lung...), M3, M4 and M1 (predominant form in muscle and brain). In foetal tissues an extra band M2, called M2f, more anodic than M2, was added to the previously described isozymes. Except in brain (in which the isozymes M2, M3, M4 and M1 were found), the most anodic bands (M2f, M2 and M3) were predominant in all the foetal tissues. The isozymes M2f and M2 seem therefore to be the original M type pyruvate kinase forms from which the other isozymes issue. The rate of each isozyme seems to depend on tissue factors characterizing the state of differentiation of some tissues, as indicated by the ability of adult muscle extracts to change the isozymes M2 and M3 into more cathodic forms.
Adult↗
Hereditary hemolytic anemia with erythrocyte phosphofructokinase deficiency: studies of some properties of erythrocyte and muscle enzyme.
A case of hereditary nonspherocytic hemolytic anemia associated with partial erythrocyte PFK deficiency without muscular symptoms is reported: erythrocyte enzyme activity in the propositus was 60% of normal. Kinetic studies of erythrocyte PFK revealed increased sensitivity to ATP inhibition and decreased sensitivity to citrate inhibition. Muscle PFK from the patient had a normal enzymatic activity, but was highly unstable to heat, dilution without stabilizer and urea; furthermore its starch gel electrophoretic mobility was markedly faster than the one of a normal control. The results suggested that a muscle type's subunit was deficient in the erythrocyte PFK. The authors hypothesize that there was no PFK deficiency in the patient's muscle because of the active synthesis of proteins by this tissue. In contrast, the deficiency of PFK would be easily detected in erythrocytes, because of the absence of protein synthesis.
Adenosine Triphosphate↗
Glucose-phosphate isomerase deficiency due to a new variant (GP I Barcelona) and to a silent gene: biochemical, immunological and genetic studies.
A 12-year-old girl of Spanish origin was found to be double heterozygote for a deficient GP I variant (GP I Barcelona) and for a silent GP I gene. The mother was heterozygote for GP I Barcelona and the father was heterozygote for the silent gene. GP I Barcelona was a fast variant (116%) with an increased isoelectric point (9.55), lability to heat and to urea, and shift of the pH curve towards the acidic pH. The other kinetic characteristics were normal. The ratio of enzymatic activity to immunological reactivity was normal in erythrocytes and white blood cells of the father and the mother but decreased to 75% of normal in blood cells of the daughter. The genetic and molecular mechanisms of GP I deficiency of this patient are discussed.
Adult↗
Serum triiodothyronine levels in patients receiving L-thyroxine.
Serum triiodothyronine (T3) and thyroxine (T4) levels were measured in 103 adult patients receiving sodium L-thyroxine (Synthroid), 0.2 or 0.3 mg daily for at least 3 mo, as suppression or replacement therapy. All were judged to be clinically euthyroid at the time of the measurements. The mean +/-SD T3 level during treatment was 130.3 +/-47.5 ng% and the mean T4 level was 11.0 +/-2.0 mug%. In normal untreated euthyroid subjects, the mean T3 level was 115.4 +/-26.0 ng% and the mean T4 level was 8.0 +/-1.7mug%. When sodium L-thyroxine was added in vitro to the stored sera of 10 hypothyroid patients to produce serum T4 levels equivalent to those that the patients later showed in vivo while on therapy, the cross-reaction was 0.85%. Thus at a mean T4 level of 11.0 mug%, there was a mean T3 level of 93.5 ng% that could be attributed to the added thyroxine itself. This cross-reaction was found to be due to contamination of the added sodium L-thyroxine with T3 and not due to cross-reactivity of the T3 antibody in the immunoassay system with T4. For 3 other brands of sodium L-thyroxine, the T3 contamination of the added T4 was 0.75%, 0.55%, and 0.40%. When 6 hypothyroid patients were given 5 mug of L-triiodothyronine (Cytomel) daily for 4 wk, there was no rise in serum T3 levels. When the same patients were switched to sodium L-thyroxine, 0.2 mg daily, serum T3 levels rose from a mean +/-SD of 60.0 +/-16.3 ng% to a mean of 130.0 +/-38.0 ng%. It would thus appear that in patients receiving sodium L-throxine therapy, the resulting serum T3 levels are due to extrathyroidal conversion of the administered T4 to T3, and not to the T3 present in the L-thyroxine administered.
Antibody Specificity↗
Patient-initiated rapid atrial pacing to manage supraventricular tachycardia.
Patient-controlled rapid atrial pacing was used to manage 12 cases of recurrent supraventricular tachycardia refractory to drug therapy. The pacing system consists of an implanted receiver-lead system and an external patient-activated transmitter. In each case, brief periods (5 to 20 seconds) of rapid atrial pacing were effective in terminating the supraventricular tachycardia and resulted in a return to normal sinus rhythm. In three patients, occasional transient episodes of atrial flutter or atrial fibrillation preceded a spontaneous return to normal sinus rhythm. The pacing system was removed in one patient 13 months postoperatively because of persistent pericarditis; one patient died of an unrelated cerebral hemorrhage 13 months postoperatively. Successful management of supraventricular tachycardia has been maintained in the 10 remaining patients for 15 to 36 months (average 26.4). In more than 6,000 patient applications of rapid atrial pacing, there has been only one failure to convert the tachycardia. Successful application of permanent rapid atrial pacing requires (1) prescreening of patients with temporary external rapid atrial pacing to verify susceptibility to conversion of supraventricular tachycardia and absence of anomalous conduction pathways that may permit conduction of rapid pacing rates to the ventricles, and (2) assessment of the patient's ability to use the transmitter properly.
Adult↗
Scintigraphic evaluation of liver size in children and adults.
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Adolescent↗
Human leukocyte glucose-phosphate-isomerase purification by affinity elution and immunological study.
The authors have purified glucose phosphate isomerase (GPI) from human leukocytes ; they used as starting material leukemic leukocytes obtained from a patient with hyper-leukocytic acute myeloid leukemia ; it was possible to obtain several milligrams of pure enzyme from a single patient. The purification procedure includes a two step precipitation by ammonium sulfate and one column chromatography on a cation exchanger with specific elution by 6 phosphogluconate, a ligand of GPI ; of the two cation exchangers tested, phosphocellulose was found to lead to a better yield than CM-Sephadex. The end product of purification had a specific activity of 855 UI/mg and gave only one band in sodium dodecyl sulphate polyacrylamide gel electrophoresis. Anti GPI monospecific rabbit serum was obtained with purified enzyme. GPI from the various blood cells of ten normal controls was studied immunologically and the ratio of the enzymatic activity to the immunological reactivity was measured ; this ratio (i.e. the molecular specific activity) was lower in granulocytes than in lymphocytes and still more depressed in platelets and hemolysate. The significance of such differences is discussed.
Blood Platelets↗
Modifications of purified glucose-6-phosphate dehydrogenase and other enzymes by a factor of low molecular weight abundant in some leukemic cells.
Highly purified platelet glucose-6-phosphate dehydrogenase (G6PD; D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) can be modified in its isoelectric point and its molecular specific activity by extracts of some leukemic granulocytes. The "G6PD modifying factors" are relatively small molecules (molecular weight slightly under 5000), thermostable, dialyzable, and ultrafilterable. These molecules are destroyed by various endo- and exopeptidases and by serine enzymes present in crude extracts of leukocytes and commercial preparations of ribonuclease. The alterations of platelet G6PD due to the "G6PD modifying factors" are stable and not reversible by dialysis or further chromatography. The leukemic extracts which are able to modify G6PD also can modify the electrophoretic mobility and (or) the enzymatic activity of purified leukocyte pyruvate kinase, 6-phosphogluconate dehydrogenase, and glucosephosphate isomerase. The chemical nature of such modifications and their relationships with post-translational modifications which occur in leukemic or normal cells are discussed.
Blood Platelets↗