Rosa Mangerini

Accelerated senescence in the kidneys of patients with type 2 diabetic nephropathy

We examined the hypothesis that senescence represents a proximate mechanism by which the kidney is damaged in type 2 diabetic nephropathy (DN). As a first step, we studied whether the senescence-associated beta-galactosidase (SA-beta-Gal) and the cell cycle inhibitor p16INK4A are induced in renal biopsies from patients with type 2 DN. SA-beta-Gal staining was approximately threefold higher (P < 0.05) than in controls in the tubular compartment of diabetic kidneys and correlated directly with body mass index and blood glucose. P16INK4A expression was significantly increased in tubules (P < 0.005) and in podocytes (P = 0.04). Nuclear p16INK4A in glomeruli was associated with proteinuria (P < 0.002), while tubular p16INK4A was directly associated with body mass index, LDL cholesterol, and HbA1c (P < 0.001-0.05). In a parallel set of experiments, proximal tubule cells passaged under high glucose presented a limited life span and an approximately twofold increase in SA-beta-Gal and p16INK4A protein. Mean telomere lengths decreased approximately 20% as an effect of replicative senescence. In addition, mean telomere decreased further by approximately 30% in cells cultivated under high glucose. Our results show that the kidney with type 2 diabetic nephropathy displays an accelerated senescent phenotype in defined renal cell types, mainly tubule cells and, to a lesser extent, podocytes. A similar senescent pattern was observed when proximal tubule cell cultures where incubated under high-glucose media. These changes are associated with shortening tubular telomere length in vitro. These findings indicate that diabetes may boost common pathways involving kidney cell senescence, thus reinforcing the role of the metabolic syndrome on biological aging of tissues.

Mutant presenilin 1 increases the expression and activity of BACE1

Mutations of the presenilin 1 (PS1) gene are the most common cause of early onset familial Alzheimer disease (FAD). PS1 mutations alter the activity of the γ-secretase on the β-amyloid precursor protein (APP), leading to selective overproduction of β-amyloid (Aβ) 42 peptides, the species that forms oligomers that may exert toxic effects on neurons. Here we show that PS1 mutations, expressed both transiently and stably, in non-neuronal and neuronal cell lines increase the expression and the activity of the β-secretase (BACE1), the rate-limiting step of Aβ production. Also, BACE1 expression and activity are elevated in brains of PS1 mutant knock-in mice compared with wild type littermates as well as in cerebral cortex of FAD cases bearing various PS1 mutations compared with in sporadic AD cases and controls. The up-regulation of BACE1 by PS1 mutations requires the γ-secretase cleavage of APP and is proportional to the amount of secreted Aβ42. Aβ42, and not AICD (APP intracellular domain), is indeed the APP derivative that mediates the overexpression of BACE1. The effect of PS1 mutations on BACE1 may contribute to determine the wide clinical and pathological phenotype of early onset FAD.

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.

Polyclonal origin of medullary carcinoma of the thyroid in multiple endocrine neoplasia type 2

Abstract Multiple endocrine neoplasia type 2 (MEN 2) is a dominantly inherited cancer syndrome characterized by medullary thyroid carcinoma (MTC) and other tumors. Since MTC can also occur in a sporadic form and as familial medullary thyroid carcinoma, this neoplasm offers a unique opportunity to investigate the difference of origin, if any, between the sporadic and the hereditary forms of a tumor. While sporadic malignancies have usually been found to result from a mutational event occurring at the single-cell level and are therefore monoclonal, studies on hereditary neoplasms have been scarce and often produced conflicting results. In order to determine the clonal origin of sporadic MTCs and of those occurring in MEN 2 syndromes we used a clonality assay based on a polymorphic trinucleotide repeat of the X-linked human androgen-receptor gene. We found that 10 out of 11 MTCs expressed a polyclonal pattern of X inactivation, including a significant percentage of the cases clinically defined as sporadic.

Heterogeneity of clonal development in chronic myeloproliferative disorders

Recent reports have suggested a previously unexpected variability in the expression of the dominant neoplastic clone in myeloproliferative disorders (MPD). We evaluated 49 female patients with MPD and informative at the X‐linked androgen receptor (AR) locus to establish the X chromosome inactivation pattern of hemopoietic cells. Whereas in chronic myelogenous leukemia (CML) the granulocytes (PMN) were uniformly of monoclonal origin, a striking heterogeneity of clonal development was found in PMN from patients with other MPD, with up to 50% of them expressing a polyclonal pattern of X inactivation. Am. J. Hematol. 60:158–160, 1999.

Clonal granulocytes in polycythaemia vera and essential thrombocythaemia have shortened telomeres

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.

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

Summary. 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. The data obtained in the present investigation show, using a different tool (MB), that catalase is the active enzyme in H2O2 detoxification and that its integrity is largely dependent on an adequate generation of NADPH.