Emanuele Salvidio

Cytogenetic analysis in essential thrombocythemia at diagnosis and at transformation: A 12-year study☆

Between 1979 and 1988, 86 patients with clinical and laboratory findings consistent with essential thrombocythemia (ET) were karyotyped at diagnosis. Four patients showed a Philadelphia chromosome and underwent myeloid blastic crisis 2.5-4.5 years later, strongly suggesting a diagnosis of chronic myeloid leukemia. A partial deletion of 13q was seen in another case evolving to leukemia a few months later. Five cases, with normal karyotypes at diagnosis, developed acute transformation after more than 5 years of chronic phase. Four of them showed unusual clonal karyotype abnormalities involving different chromosomal regions. The numerical abnormalities found were trisomy 22 in one case, and trisomy 8 and 19 in another, while structural changes included partial deletion of 5p, partial deletion of 6q, pericentric inversion of chromosome 12, and partial deletion of 20q. These abnormalities have not been previously reported in ET. This investigation confirms the absence of a specific cytogenetic marker for ET, and the infrequent transformation to acute leukemia, often with chromosomal clonal disorders.

Favism: Erythrocyte Metabolism during Haemolysis and Reticulocytosis

Summary. The reduced activity of glucose‐6‐phosphate dehydrogenase (d‐glucose‐6‐phosphate; NADP+ i‐oxidoreductase; G6PD) in Mediterranean erythrocytes explains the precarious equilibrium of the hexose monophosphate pathway (HMP) and the susceptibility of these cells to haemolytic agents. G6PD‐deficient erythrocytes, in steady‐state conditions, have a low NADPH/NADP+ ratio, thus allowing the HMP to operate at its maximal intracellular rate and to compensate the intrinsic erythrocyte enzyme deficiency. Studies started soon after accidental intake of fava beans by sensitive G6PD‐deficient subjects demonstrate a decrease of both NADPH/NADP+ ratio and reduced glutathione. The metabolic effects induced by fava beans may be attributed to oxidative stress probably associated with an inhibitor effect of some unknown metabolite on the HMP. The availability of erythrocytes from subjects recovering from haemolysis with high reticulocyte counts and increased G6PD activity, provides new information on the rate of synthesis as well as on the in vivo decay of the mutant enzyme. Correlation of G6PD activity to reticulocyte count and extrapolation to an ideally homogenous population of reticulocytes reveal that the mutant enzyme is synthesized at a nearly normal rate. Furthermore, the present correlation allows an estimate of the in vivo half‐life of Mediterranean G6PD. The rate of decline of about 8 d observed in this study well correlates to the intracellular metabolic aspects of G6PD Mediterranean erythrocytes.

Haemolytic Effect of Two Sulphonamides Evaluated by a New Method

A technique to investigate drugs which could cause haemolysis in subjects deficient in glucosc‐6‐phosphate dehydrogenase (D‐glucose‐6‐phosphate: NADP oxidoreductase; G6PD) has been developed. The method is based on the technique of 14CO2 evolution during the incubation of normal erythrocytes in the presence of [I‐14C] glucose and their own serum, the latter containing the active metabolites of the drugs received by normal subjects. By this method agents causing a stimulation of the hexosemonophosphate pathway of normal erythrocytes should be regarded as potentially haemolytic for G6PD‐deficient subjects. Two sulphonamides, sulphormethoxine and sulphalene, of which until now no haemolytic effects have been reported, together with chloroquine, have been investigated. While chloroquine does not affect the hexosemonophosphate shunt of normal erythrocytes, the two sulphonamides stimulate this pathway. The results are confirmed by the reduction of the half‐life of 51Cr‐labelled G6PD‐deficient red cells (Mediterranean variant), after administration of the two sulphonamides.

Involvement of the short arm of the derivative chromosome 9 in Philadelphia-positive acute lymphoblastic leukemia

Three Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) patients showed rearrangement of the short arm of the chromosome 9 involved in Ph formation. At diagnosis, blast cells were morphologically L2 and phenotypically B-cell precursors, as shown by common ALL antigen (CALLA), B1, B4 and HLA-DR positivity. Cytogenetically, they had in common the presence of cells with normal karyotypes, the Ph, involvement of band 9p13----p21, and loss of region 9p13----9pter. In our experience, involvement of the p arm of the derivative chromosome 9 in Ph+ leukemias is a very rare event found in ALLs only.

Late-appearing Philadelphia chromosome in acute lymphoblastic leukemia

We describe the cytogenetic analysis of a patient affected by a common acute lymphoblastic leukemia, L2 type. At diagnosis and first relapse, the karyotype was normal, whereas at the second relapse more than 60% of the examined cells showed a Philadelphia chromosome, without any change in the morphological and immunophenotypical picture. This case confirms the observation that leukemic cells are susceptible to developing a Ph, considered a primary chromosomal abnormality, during the course of the disease.

Effect of Primaquine on Erythrocytes with NADH‐Methaemoglobin Reductase Deficiency and Low Glutathione Reductase Activity

Summary. Two young patients with congenital methaemoglobinaemia due to NADH‐methaemoglobin reductase deficiency associated with low activity of erythrocytic glutathione reductase (GSSG‐R) are described. Their red cells, labelled with 51Cr and transfused into normal recipients, were susceptible to haemolysis by primaquine with an abnormal pattern of destruction. The administration of riboflavin raised the level of erythrocyte GSSG‐R, but did not alter the level of methaemoglobin. The administration of methylene blue not only reduced the methaemoglobin to almost normal levels, but also increased the activity of GSSG‐R. During methylene blue therapy, their red cells, tagged with 51Cr and transfused into a normal recipient who was receiving methylene blue, were not susceptible to haemolysis by primaquine. Some possible reasons for the frequent association between NADH‐methaemoglobin reductase deficiency and low activity of GSSG‐R are discussed.

The Action of Coumarin Anticoagulants and of Vitamin K1 on some Enzymes of Human Blood Platelets

It is well known that Coumarin drugs interfere with the blood coagulation process through their action on prothrombin formation, factor VII (Koller), and factor X (Koller, Hunter and Walker). No influence of anticoagulants on platelet functions has hitherto been detected, and platelet number and their agglutination ability are reported to remain unchanged during the administration of the drugs (Jurgens).