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Biomedical subjects

A Kahn

Publications and source records attributed to A Kahn.

At least 595 records · Page 33Linked to original sources
PubMed1977

A Spanish family with erythrocyte pyruvate kinase deficiency: contribution of various immunologic methods in the study of the mutant enzyme.

Erythrocyte PK deficiency was detected in a 38-year-old man from Catalonia, in Spain. His father and his three children were proven to be heterozygous for the same mutant PK variant. This variant was characterized by low immunologic specific activity, normal (or slightly increased) stability to heat and to urea; normal isoelectric point, increased K0.5 for phosphoenolpyruvate, increased inhibition by ATP and normal activation by 0.35 mM fructose 1,6-diphosphate. The mutant PK variant was antigenically identical with wild enzyme as tested against anti wild erythrocyte PK serum by double immunodiffusion and micro complement fixation. The utility and the significance of the immunologic methods to be used in the study of mutant PK variants are discussed.

Adult↗
PubMed1977

Glucose-6-phosphate dehydrogenase Velletri.

A new variant of red cell glucose-6-phosphate dehydrogenase (G6PD) has been found in a Caucasian man with congenital non-spherocytic haemolytic anaemia. This variant has reduced activity, increased thermolability, increased Michaelis constants for glucose-6-phosphate and NADP, slightly increased electrophoretic mobility, and a biphasic pH-activity profile. The red cell adenine compounds and ATP, are in normal limits. The increased activity of red cell NADP-glutathione reductase is probably the expression of a mechanism of compensation for the decrease of G6PD and a consequence of the decrease of NADPH.

Anemia, Hemolytic, Congenital Nonspherocytic↗
PubMed1977

Accuracy of portein synthesis and in vitro aging. Search for altered enzymes in senescent cultured cells from human livers.

The authors have looked for altered proteins in senescent cultured cells from adult liver. Four enzymes (phosphoglycerate kinase, M2 type pyruvate kinase, glucose phosphate isomerase and glucose-6-phosphate dehydrogenase) have been studied by immunological and enzymatic titration and electrofocusing. In addition, heat stability of glucose-6-phosphate dehydrogenase (G6PD) was appraised in cell crude extracts and in partially purified preparations. Enzymatic aactivity as well as immunological reactivity of the four enzymes studied were identical 16 lines in phase II and in 13 lines in phase III. Electrofocusing pattern of the enzymes from 'young cells' was identical to the ones from 'old cells'. Finally, G6PD from old cells seemed to be more unstable than G6PD from young cells when studied in crude extracts. These differences, however, disappeared as G6PD was partially purified from old or young cultured cells. Consequently, no evidence of altered protein, either missynthesized or posttranslationally modified, was found in the senescent cultured cells studied. Moreover, this work indicated that the modification of heat stability of G6PD from old cells was not due to the enzyme molecule itself but rather to the cell medium.

Aging↗
PubMed1977

Possible molecular mechanisms of ageing.

While the error theory of ageing has attracted most interest in recent times it cannot yet be regarded as being demonstrated. Posttranslational modifications of proteins genetic theory appears loical but has little in vivo evidence to prove it. Basic mechanisms of ageing probably involve the interaction of several processes.

Aging↗
PubMed1977

Purification of L-type pyruvate kinase from human liver by affinity chromatography on Blue-Dextran-Sepharose column.

L-type pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase; EC 2.7.1.40) was purified from human liver by an original method. This purification included toluene extraction, a-monium sulphate fractionation, DEAE-Sephadex bactchwise, CM-Sephadex batchwise with elective elution by ATP and affinity chromatography on a Blud Dextran-Sepharose column with specific elution by fructose 1, 6-diphosphate. This purification procedure allowed us to obtain 6 mg protein with a specific activity of 420 IU/mg protein, i.e. 2,690-fold purification with an overall yield of 34%. This preparation was homogeneous as judged by immuno-diffusion, acrylamide and sodium dodecyl sulphate acrylamide-gel electrophoresis.

Chromatography, Affinity↗
PubMed1977

Congenital stridor in infancy. Clinical lessons derived from a survey of 31 instances.

Thirty-one cases of persistent stridor during infancy, which on study proved to be of congenital origin, were analyzed. The breakdown of these cases is as follows: 4 laryngotracheomalacia, 3 vascular anomalies, 4 angiomas, 1 mucous membrane, 1 laryngeal cyst. The remaining cases (18) belong to the so-called "benign" stridor group in that no specific etiology could be demonstrated and in that evolution was spontaneously favorable. In every case of stridor, the precise underlying cause should be looked for. In addition to clinical assessment the investigation of an infant with stridor calls for the following methods of examination: chest x-ray; larynx x-ray (anterior and lateral view) during iopneumography should be confined to specific cases.

Airway Obstruction↗
PubMed1977

Immunologic study of the age-related loss of activity of six enzymes in the red cells from newborn infants and adults--evidence for a fetal type of erythrocyte phosphofructokinase.

Blood from 10 normal healthy adults and cord blood from 8 healthy full term infants were infiltrated through a mixture sulfoethylethycellulose-Sephadex G 25 in order to eliminate the platelets and the leukocytes. Then the erythrocytes were fractionated into young and old cells by centrifugation in microhematocrit tubes. The enzyme activity and the immunologic reactivity of glucose phosphate isomerase (EC.5.3.1.9), phosphoglycerate kinase (EC.2.7.2.3), pyruvate kinase (ec.2.7.1.40), glucose 6-phosphate dehydrogenase (EC. 1.1.1.49), and 6-phosphogluconate dehydrogenase (EC.1.1.1.44) were measured in every fraction. As previously reported, the enzyme activities were far higher in cord blood than in adult blood red cells; nevertheless, the age-related loss of enzyme activity was similar in both cord and adult blood. The decrease of the enzyme activity of glucose phosphate isomerase and phosphoglycerate kinase in old cells was singly associated with a lowered concentration of the enzyme-related antigen; by contrast, the age-related decrease of the enzyme activity of pyruvate kinase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase was associated with both a lowered concentration of the enzyme-related antigen and a lowered "molecular specific activity" (i.e., a lowered ratio of enzyme activity to enzyme-related antigen concentration). This phenomenon was especially marked for pyruvate kinase, which had a molecular specific activity in old cells that was 68% of that in young cells. Phosphofructokinase had a lower enzyme activity in cord blood erythrocytes than in adult blood erythrocytes; the difference was especially important in old cells from infants in which phosphofructokinase activity was 53% of that in old cells from adults. Phosphofructokinase from old cells of full term infants and from unfractionated cells from two premature infants (21 and 32 weeks of gestation) was less neutralized by anti-muscle phosphofructokinase serum and more inhibited by ATP than the enzyme from adult blood erythrocytes.

Adenosine Triphosphate↗
PubMed1977

Intramural hematoma of the alimentary tract in two hemophilic children.

The occurrence of an intramural hematoma of the alimentary tract is reported in two hemophilic children. In both cases, the hematomas may be the result of a mild unrecognized trauma. The first patient presents large duodenal hematomas with secondary rupture into the retroperitoneal space. Death occurs despite medical and surgical treatment. The second patient presents an intramural hematoma of the colon, which is treated medically. In both cases factor VIII inhibitors developed during the course of therapy. Indications for medical or surgical treatment are discussed.

Barium Sulfate↗