Oxygen affinity and electrolyte distribution of human blood: changes induced by propranolol.

Propranolol causes a massive leakage of potassium ions from red cells, which results in an alteration of the Gibbs-Donnan equilibrium across the red cell membrane. According to such a mechanism, the presence of propranolol significantly increases the hydrogen ion activity of the interior of the red cell, causing a decreased oxygen affinity of hemoglobin according to the classical Bohr effect. No release of 2,3-diphosphoglycerate which may be bound to the membrane is thus necessary to explain the effect of propranolol on the oxygen dissociation curve of blood.

Erythrocyte antioxidant enzymes and selenium serum levels in an Andean population.

A preliminary study indicated that erythrocyte antioxidant enzyme activities were enhanced in chronic hypoxaemic patients, in whom an increased oxidant stress could be present as a consequence of augmented haemoglobin autoxidation. We have now evaluated the behaviour of erythrocyte antioxidant enzymes and of their related trace metal serum levels in conditions of chronic hypobaric hypoxia in an Andean population living at high altitude (3800 m above sea level), and in a similar ethnic group living at sea level. The results indicate a significant reduction in erythrocyte glutathione peroxidase activity and a low serum level of selenium in the Andean population. Thus, in contrast to what happens in chronic hypoxaemic patients, this group of Andean subjects seems to be poorly protected against oxidant stress, probably as a consequence of selenium deficiency in the diet.

Serum myoglobin, total CK and MB CK isoenzyme after D.C. cardioversion and during the early phase of acute myocardial infarction.

Myoglobin, total CK and MB CK isoenzyme were determined in the sera of 6 patients admitted with arrhythmias and treated with D.C. countershock and also in 37 patients with acute myocardial infarction or anginal syndrome. All the three tests were increased in patients with myocardial infarction. Serum myoglobin seems sufficiently sensitive and specific but the time required for the assay is a limiting factor for practical use in emergencies. After electrical cardioversion, myoglobin and CPK remain normal, although MB isoenzyme was increased in two of six patients. These results suggest that electrical cardioversion in itself does not influence serum levels of myoglobin. The occasional increase of MB CK observed after cardioversion seems to be the consequence of an easier release of the enzyme due to a myocardial injury.

[Methemoglobinemia; a description of a case of NADH methemoglobulin reductase deficiency]. / La metaemoglobinemia; Descrizione di un caso da deficit di NADH-metaemoglobin-reduttasi.

A case of NADH-methaemoglobin-reductase deficiency in a 64 year old man with marked cyanosis and without evidence of cardiac or pulmonary diseases is reported. The level of methaemoglobin was 36% and reached 25% after treatment with ascorbic acid. Erythrocyte NADH-methaemoglobin-reductase activity was only 5% of normal value. Some erythrocyte biochemical and enzymatic characteristics have been evaluated. A family study has also been carried out. Our patient has been considered homozygous for NADH-methaemoglobin-reductase deficiency.

Prevalence of retinopathy in patients with anemia or thrombocytopenia.

BACKGROUND AND OBJECTIVES: Fundus lesions can be the accompanying symptom in many hematological diseases. In cases of anemia or thrombocytopenia, the exact mechanism leading to fundus abnormalities is not completely understood. The aim of this study was to calculate the prevalence of fundus lesions in anemic and thrombocytopenic patients, and define the risk factors for retinopathy. DESIGN AND METHODS: This cross-sectional study involved 226 patients with anemia and/or thrombocytopenia and a control group of 47 age-matched subjects. The studied variables were age, gender, hemoglobin levels, mean cell volume (MCV), red cell distribution width coefficient variation (RDW-CV), the type of onset of anemia, platelet counts, mean platelet volume (MPV), platelet distribution width (PDW), the platelet-large-cell ratio (P-LCR), prothrombin time (PT) and partial thromboplastin time (PTT). RESULTS: Retinopathy was observed in 28.3% of the patients as a whole, the presence of fundus lesions being closely associated with severe anemia (Hb < 8 g/dL) and severe thrombocytopenia (PLT < 50 x 109/L). Among the patients with concomitant anemia and thrombocytopenia, the incidence of retinopathy was 38%. Age, low hemoglobin levels, platelet counts, RDW-CV, and increased MCV, MPV and P-LCR were all significantly associated with the presence of fundus lesions at univariate analysis. INTERPRETATION AND CONCLUSIONS: Retinopathy is a frequent finding in anemic and thrombocytopenic patients, although it is often not significant clinically. As retinal hemorrhages were found in all of the patients with concomitant severe anemia and thrombocytopenia, it is recommended that all such patients undergo routine fundus examinations.

G-6PD loading of G-6PD-deficient erythrocytes.

G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.

Erythrocyte superoxide dismutase, catalase and glutathione peroxidase activities in beta-thalassaemia (major and minor).

The 'antioxidant' enzymes superoxide dismutase (SD), catalase and glutathione peroxidase (GSH-Px) were found greatly elevated in red blood cells of subjects with beta-thalassaemia minor and similar to normal values in red blood cells of subjects with beta-thalassaemia major. These findings allows us to speculate that red cells in beta-thalassaemia minor react to the increased oxidant threat with augmented antioxidant enzyme activities. The normal levels of antioxidant enzymes in beta-thalassaemia major seem to be due to the presence of normal red cells owing to multiple transfusions.

Erythrocyte antioxidant system and serum ceruloplasmin levels in welders.

The erythrocyte antioxidant system (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione) and serum ceruloplasmin were studied in workers chronically exposed to welding fumes and gases, which are thought to be oxidant pollutants. Fifty-four healthy men using two electric arc welding processes (manual metal arc on stainless steel and mild steel, and metal inert gas on mild steel) were studied. The possible effects of cigarette smoking were also considered. The erythrocyte antioxidant system was in the normal range for all welders. Serum ceruloplasmin was significantly enhanced only in smoking welders and higher in manual metal arc than in metal inert gas welders, suggesting that the increase is related to the severity of the oxidant threat, which is more stressful for the workers using the manual metal arc technique because of the presence of stainless steel particles in the fumes. Although cigarette smoking alone did not increase serum ceruloplasmin levels, it affected the response to oxidant stress in welders.

Antioxidant system in sickle red cells.

Erythrocytes containing abnormal haemoglobins with high affinity for red cell membrane are subjected to enhanced oxidant stress. Since HbS is known to have high affinity for red cell membrane and sickle cells are particularly susceptible to membrane lipid peroxidation, the behaviour of erythrocyte antioxidant system has been evaluated in 20 subjects, heterozygous for sickle cell anaemia. These subjects have shown normal levels of reduced glutathione, increased superoxide dismutase and glutathione peroxidase activities and low catalase activity. These data suggest that such an unbalanced antioxidant system can not prevent damage by the enhanced production of oxygen free radicals by membrane-bound HbS molecules.

[Glucose-6-phosphate dehydrogenase deficiency among the student population of Milan]. / Le déficit en glucose-6-phosphate deshydrogénase dans la population scolaire de Milan.

In our Department a yearly screening is carried out on the school population of Milan, in order to detect beta-thalassaemic trait carriers and G-6-P-D deficient males. This report deals with the results obtained on a group of 21,118 males. They all showed very low enzyme activity and often just detectable; the fall of GSH after incubation with acetylphenhylhidrazine appeared significantly greater than normal. Only 3 cases of hemolytic crises by fava beans ingestion and 7 cases of neonatal jaundice resulted from anamnestic data.

Erythrocyte superoxide dismutase, catalase and glutathione peroxidase in glucose-6-phosphate dehydrogenase deficiency.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficient erythrocytes are particularly sensitive to oxidant stress. In order to evaluate if these cells are protected against oxidant damage, we assayed the antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px) in erythrocytes of G-6-PD deficient (hemizygous and heterozygous) subjects. Normal levels of antioxidant enzymes were found in all subjects examined both with positive and negative histories of haemolytic crisis after fava bean or drug ingestion. In contrast, high levels of catalase and GSH-Px were found in a small group of G-6-PD deficient subjects (hemizygous and heterozygous) with beta-thalassaemia trait, probably by reason of the chronically enhanced oxidant stress which is present in beta-thalassaemia.

Superoxide dismutase, catalase and glutathione peroxidase activities in maternal and cord blood erythrocytes.

The "antioxidant" enzymes superoxide dismutase, catalase and glutathione peroxidase were assayed in a biological model with low oxygen tension (red cells from cord blood of newborn infants). Catalase and glutathione peroxidase activities in red cells of newborns were significantly lower when compared with their mothers and with normal controls. In contrast, superoxide dismutase activity was unchanged. Thus, normal activities of superoxide dismutase seem to be necessary in order to protect red blood cells from superoxide radicals during foetal life, while even low activities of catalase and glutathione peroxidase are sufficient to protect red blood cells from hydrogen peroxide. No correlation was found between the "antioxidant" enzyme activities present in cord blood erythrocytes and the bilirubin concentrations during the first days of life.

Erythrocyte glutathione peroxidase in subjects of Mediterranean origin. A family study.

Erythrocyte glutathione peroxidase (GSH-Px) was assayed in subjects of Mediterranean origin and the distribution of the data obtained seems to confirm the existence of two alleles coding for low and high enzyme activity. In order to define the limits of expected genotypes less arbitrarily we studied families where parents' genotypes could allow us to define that of the children. Gene frequencies were calculated from genotype frequencies of an unrelated population and from crossings distribution by the Hardy-Weinberg equation. We observed a good agreement between gene frequencies obtained by these two different methods.

Antioxidant system and serum trace elements in alpha-thalassaemia and Hb Lepore trait.

Erythrocyte antioxidant enzymes, superoxide dismutase, catalase and glutathione peroxidase were found to be significantly high in subjects with alpha-thalassaemia and Hb Lepore trait, as a consequence of the increased oxidant stress which is known to exist in these conditions. Among the serum trace elements present in these enzymes, selenium was increased in subjects with Hb Lepore trait and significantly low in those with alpha-thalassaemia trait, while selenium erythrocyte content was significantly increased in alpha-thalassaemic subjects.