G. Perona

In Vivo and in Vitro Variations of Human Erythrocyte Glutathione Peroxidase Activity as Result of Cells Ageing, Selenium Availability and Peroxide Activation

Cases showing erythrocyte glutathione peroxidase (GSH‐Px) defects have been previously described. Our experiments demonstrate that a number of non genetic factors may influence the GSH‐PX activity in human erythrocytes.

Neonatal erythrocyte glutathione peroxidase deficiency as a consequence of selenium imbalance during pregnancy.

Summary. The red blood cell (RBC) glutathione peroxidase (GSH‐Px) activity and routine haematological parameters were measured in 38 healthy north Italian full‐term pregnant women and in their newborn infants. In 31 pairs the serum selenium concentration was also measured. Data were compared with those of 20 normal adult controls (10 males and 10 females).

Ham-positive Red Cells Induced In vitro by N-Acetylcysteine or D-Penicillamine

Red cells incubated with N‐acetylcysteine or D‐penicillamine in appropriate concentrations become sensitive to lysis by acidified normal human serum, i.e. become PNH‐like cells and give a positive Ham test. At the same time the cells lose some of their acetylcholinesterase activity. Substances active in this way share a common chemical grouping:

LOSS OF ACETYLCHOLINESTERASE IN HUMAN ERYTHROCYTES TREATED WITH TRYPSIN, PAPAIN OR BROMELIN: ITS RELATIONSHIP WITH SUSCEPTIBILITY TO ACID LYSIS IN VITRO.

YACHNIN and his associates were able to demonstrate that normal human red cells treated with various proteolytic enzymes, cholera vibrio filtrate, influenza virus and periodate ion, became susceptible to acid lysis in compatible human serum like paro,xysmal nocturnal haemoglobinuria (PNH) red cells ( Y a c h , Laforet and Gardner, 1961; Y a c h and Gardner, I 96 I a, b) . On the other hand, it has been found by several groups of workers (de Sandre, Ghiotto andMastella, 1956b; de Sandre andGhiotto, 1958,1960; Auditore and Hartmann, 1959; Metz, Bradlow, Lewis and Dacie, 1960) that PNH red cells susceptible to acid lysis (i.e. giving a positive Ham test) have a remarkable deficiency of stromal acetylcholinesterase (AchE) activity. This enzyme deficiency is not a consequence of dubition: the almost complete inhbition of normal human red cells AckE with diisopropylfluorophosphonate does not reduce their irz vivo survival (Perona, Ghiotto, Scandellari and Frezza, 1963). In order to clarify the relationship between stromal AchE activity and red-cell susceptibhty to acid lysis, we are conducting an investigation of the behaviour of these phenomena in normal erythrocytes treated with the various agents used by Yachnin and his associates. In the present paper we report the results obtained in red cells incubated with proteolytic enzymes: trypsin, papain and bromelin. Some of the data concerning trypsinized red cells have already been published elsewhere (Perona, de Sandre and Gbotto, 1963).

Transglucuronidase activity of the liver: a dosage method suitable for fragments obtained with needle biopsy

Abstract A method for the determination of the transglucoronidase activity of liver is presented. It consists in the incubation at 37° for 30 min of a mixture containing liver homogenate, UDPGA Sigma as glucuronate donor, and 4-methyl-umbellipherone as glucuronate acceptor in 0.15 M TRIS buffer, pH 7.5. The method requires very small amounts of liver tissue (obtained by needle biopsy) of a wet weight not more than 10–15 mg. In the optimum conditions described, the transferase activity is shown to be higher than with methods described by other authors: 1 mg of normal liver proteins conjugate in 30 min 150–300 mμmoles of 4-MU.

On the Mechanism of the In Vitro Production of Ham-positive Red Cells by Sulphydryl Compounds: Role of pH and Free -SH Groups

Experiments were carried out in order to obtain high percentages of Ham‐positive red cells (HPRC) from normal human red cells incubated with various ‐SH containing compounds and to evaluate the role of the free ‐SH groups in these sulphydryl compounds and of the red cells themselves in the HPRC‐producing process.

Bilirubin inhibition of 4-methylumbelliferone glucuro conjugation in vitro by the human liver

Abstract The addition of bilirubin to a system containing human liver homogenate, excess of undine diphosphoglucuronic acid and 4-methylumbelliferone produces an inhibition in the glucuro-conjugation of 4-methylumbelliferone. Under these experimental conditions, the result supports the existence of a single enzyme in human liver, which conjugates both substrates: with bilirubin, an ester glucuronide is formed, and with 4-methylumbelliferone, an ethereal one.

Phenobarbitone sensitivity of jaundice in haemolytic patients

Summary. Eleven cases of chronic haemolytic jaundice treated with phenobarbitone are reported. In all patients, except one, the drug caused a significant reduction of hyperbilirubinaemia in spite of the persistence of an increased haemolysis. Radioactive bilirubin (3H) kinetic studies demonstrated a bilirubin transfer defect from plasma to liver in seven patients which improved after phenobarbitone therapy along with the reduction of bilirubinaemia. It is concluded that a phenobarbitone‐sensitive hepatic mechanism frequently operates in producing jaundice in chronic haemolytic syndromes.

Hexokinase and TPN-Dependent Dehydrogenases of Leucocytes in Leukaemia and Other Haematological Disorders

IT has been known for a long time that leukaemic leucocytes undergo marked changes involving their glycolytic and oxidative metabolism; for example, their aerobic glycolysis and respiration, when studied in phosphate medium, decrease to about one-third (Beck and Valentine, 1953)’ m a d y as a result of a lower hexokinase activity (Beck, 1958a)). This enzyme seems to be the rate-limiting factor of the glycolytic pathway, both in normal and in leukaemic leucocytes. Beck (rg58b) also reported decreased leucocyte enzyme activity in chronic inyelocytic and lymphocytic leukaemia with respect to several other glycolytic enzymes and also glucose&phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, both of which require co-enzyme I1 (triphosphopyridine nucleotide, TPN, Beck, Ig58b). These results have been partially confirmed by our previous studies (Ghiotto, De Sandre and Perona, 1960). In this paper we present some data concerning the enzymic pattern of the leucocytes of 68 patients affected by different haematological disorders. Hexokinase, glucose&phosphate dehydrogenase, 6-phosphogluconic dehydrogenase and isocitric dehydrogenase activities have been determined in chronic myelocytic leukaemia, chronic lymphocytic leukaemia, acute leukaemia, Hodgkin’s disease and osteosclerotic anaemia.