Mammalian catalase: a venerable enzyme with new mysteries.

Mammalian catalase has been the subject of many classic biochemical studies. Despite our detailed knowledge of its functional mechanisms and its three-dimensional structure, however, several unexpected features of mammalian catalase have been recently discovered. For example, some mammalian catalases seem to have oxidase activity and produce reactive oxygen species when exposed to UVB light.

Clonal granulocytes in polycythaemia vera and essential thrombocythaemia have shortened telomeres.

Summary The purpose of this study was to evaluate telomere length in peripheral blood granulocytes and mononuclear cells collected from 22 women with polycythaemia vera (PV) and essential thrombocythaemia (ET). PV and ET are chronic myeloproliferative diseases whose heterogeneity of stem cell origin and clonal development has been established through analysis of X-chromosome inactivation patterns. The results from clonality assay and determination of telomere length show that only clonal granulocytes have shortened telomeres.

High telomerase activity in granulocytes from clonal polycythemia vera and essential thrombocythemia.

Essential thrombocythemia (ET) and polycythemia vera (PV) are chronic myeloproliferative disorders that share the involvement of a multipotent progenitor cell and dominance of the transformed clone over normal hematopoiesis. On the other hand, the heterogeneity of these diseases with respect to clonal development from a common progenitor has been well established. To identify useful prognostic indicators, we analyzed telomerase activity (TA), a known marker of neoplastic proliferation, in granulocytes (PMNs) and mononuclear cells (MNCs) from 22 female patients with ET and PV.

A novel NADPH:(bound) NADP+ reductase and NADH:(bound) NADP+ transhydrogenase function in bovine liver catalase.

Many catalases have the shared property of containing bound NADPH and being susceptible to inactivation by their own substrate, H2O2. The presence of additional (unbound) NADPH effectively prevents bovine liver and human erythrocytic catalase from becoming compound II, the reversibly inactivated state of catalase, and NADP+ is known to be generated in the process. The function of the bound NADPH, which is tightly bound in bovine liver catalase, has been unknown.

Influenza vaccine in chronic lymphoproliferative disorders and multiple myeloma.

Objective: Vaccination against influenza in patients with chronic lymphoproliferative disorders (CLPD) and multiple myeloma (MM) is still a matter of clinical uncertainty. The aim of this study was to determine the safety, immunogenicity and clinical response to a commercially available vaccine against influenza in a group of such patients.

Methods: Thirty-four patients with CLPD and MM and 34 immunologically normal subjects were vaccinated with the same vaccine against influenza.

Exposure of erythrocytes to methylene blue shows the active role of catalase in removing hydrogen peroxide.

Methylene blue (MB) is a powerful reducing agent that is widely used in clinical practice as well as for metabolic studies of the erythrocyte. We have investigated the role of catalase as a specific enzyme for the removal of hydrogen peroxide by measuring the in vitro effects of MB on human red cells. In the presence of MB, catalase underwent inactivation even with the co-existence of active generation of NADPH, leaving the glutathione concentration unaffected.