Salvatore Esposito

Desmin‐free cardiomyocytes and myocardial dysfunction in end stage heart failure

Our aim was to evaluate the desmin content in the myocardial tissue of patients with end‐stage heart failure of ischaemic origin and to assess its role on cardiac function. We studied 18 explanted hearts from patients transplanted for end‐stage heart failure due to ischaemic cardiomyopathy (ICM). Control myocardial tissue was obtained from the cardiac biopsies of six women with breast cancer taken prior to commencing chemotherapy with anthracyclines, four male donors for heart transplantation and two autoptic hearts from patients who died due to non‐cardiac events. Myocardial tissue, obtained from the left ventricle (remote zone from infarcted area), was analyzed by light and confocal immunochemistry (desmin) microscopy. The desmin content of myocardial tissue was obtained by real‐time PCR. Cardiac function was evaluated by echocardiographic and right heart catheterization data, obtained before heart transplantation. Confocal microscopy evaluation showed a significant decrease in the number of desmin‐positive myocytes (P<0.01) in ICM hearts compared to controls. At real‐time PCR evaluation, there was a reduction (P<0.01) in desmin content in the ICM patients compared to controls. A negative correlation was found between desmin‐free cardiomyocytes and ejection fraction (EF) (r=−0.834; P<0.02) on echocardiogram. A negative relationship (r=−0.688) was also found between desmin‐negative myocytes and capillary wedge pressure. In conclusion, the myocardial tissue of patients with end‐stage heart failure of ischaemic origin, shows a decreased number in desmin‐positive myocytes at immunochemistry evaluation compared to normal individuals. This deficiency in cytoskeletal intermediate filament content is associated with reduced cardiac function.

Surgical pathology of the mitral valve: gross and histological study of 1288 surgically excised valves

A consecutive series of 1288 mitral valves surgically excised from 1981 through 1989 were studied macroscopically and histologically. The explanted valves were affected by: chronic rheumatic disease (1179, 91.5%), floppy mitral valve (84, 6.5%), bacterial endocarditis (19, 1.5%), and post-ischemic mitral incompetence (6, 0.5%). Among 1179 post-rheumatic cases, mixed mitral stenosis and incompetence was the most frequent malfunction (747, 58%). Isolated mitral incompetence was diagnosed in 72 (6.11%) cases only, and isolated stenosis in 360 cases. In 52 valves, excised because of chronic rheumatic disease, the histology showed unexpected signs of acute rheumatism of the leaflets and the papillary muscles. In these patients clinical symptoms and blood tests were negative for rheumatic disease. Mitral incompetence, possibly due to papillary muscle dysfunction, was the prevalent lesion (61.5%). A total of 181 patients (14.05%) with pure mitral incompetence underwent surgery. In 84 patients (46.4%), the floppy mitral valve was the most frequent cause of valve dysfunction, 72 (39.8%) had rheumatic disease, 19 (10.5%) infective endocarditis, and 6 (3.4%) ischemic heart disease. In the group with floppy mitral valve, males were more prevalent than females (51:33). The mean age of the 4 patients with Marfans syndrome and non-Marfan patients was noticeably different (17 vs 49 yr). Moreover leaflet deformation, tendinous cord elongation and annulus dilatation were the most common causes of valve incompetence. Floppy mitral valve and infective endocarditis were the cause of cordal rupture in 43.5% of the cases. This was a severe complication which always required emergency surgery.

A GEOMETRIC PICTURE FOR FERMION MASSES

We describe a geometric picture for the pattern of fermion masses of the three generations which is invariant with respect to the renormalization group below the electroweak scale. Moreover, we predict the upper limit for the ratio between the Dirac masses of the μ and τ neutrinos,

THE ACTION OF NEUTRINO PONDEROMOTIVE FORCE ON SUPERNOVA DYNAMICS

Collective interactions of a beam of neutrinos/antineutrinos traversing a dense magnetized plasma of electrons/positrons, protons and neutrons are studied with particular reference to the case of a supernova. We find that the ponderomotive force exerted by neutrinos gives, contrary to expectations, a negligible contribution to the revival of the shock for a successful supernova explosion, although new types of convection and plasma cooling processes induced by the ponderomotive force could be, in principle, relevant for the dynamics itself.

FLAVOR-CONSERVING OSCILLATIONS OF DIRAC-MAJORANA NEUTRINOS

We analyze both chirality-changing and chirality-preserving transitions of Dirac–Majorana neutrinos. In vacuum, the first ones are suppressed with respect to the others due to helicity conservation and the interactions with a (normal) medium practically does not affect the expressions of the probabilities for these transitions, even if the amplitudes of oscillations change slightly. For usual situations involving relativistic neutrinos we find no resonant enhancement for all flavor-conserving transitions. However, for very light neutrinos propagating in superdense media, the pattern of oscillations is dramatically altered with respect to the vacuum case, the transition probability practically vanishing. An application of this result is envisaged.

Pontecorvo neutrino - anti-neutrino oscillations: Theory and experimental limits

We study Pontecorvo neutrino–antineutrino oscillations both in vacuum and in matter within a field theoretic approach, showing that this phenomenon can occur only if neutrinos have a Dirac–Majorana mass term. We find that matter effects suppress these oscillations and cannot explain the solar neutrino problem. On the contrary, a vacuum neutrino–antineutrino oscillations solution to this problem exists. We analyze this solution and the available data from laboratory experiments giving stringent limits on νe and νμ Majorana masses.

Dicer-like and RNA-dependent RNA polymerase gene family identification and annotation in the cultivated Solanum tuberosum and its wild relative S. commersonii

Main conclusionWe provide advances in DCL and RDR gene diversity in Solanaceae. We also shed light on DCL and RDR gene expression in response to cold stress.DICER-like (DCL) and RNA-dependent RNA polymerase (RDR) genes form the core components to trigger small non-coding RNA (ncRNA) production. In spite of this, little is known about the two gene families in non-model plant species. As their genome sequences are now available, the cultivated potato (Solanum tuberosum) and its cold-tolerant wild relative Solanum commersonii offer a valuable opportunity to advance our understanding of the above genes. To determine the extent of diversification and evolution of DCLs and RDRs in these species, we performed a comparative analysis. Seven DCLs were identified in the two species, whereas seven and six RDR genes were found in S. tuberosum and S. commersonii, respectively. Based on phylogenetic analysis with DCLs and RDRs from several species, we provide evidence for an increase in their number in both potato species. We also disclosed that tandem duplications played a major role in the evolution of these gene families in Solanaceae. DCL and RDR expression was investigated in different tissues and under cold and virus stresses, with divergent profiles of the tandem duplicated genes being found in different tissues. DCL paralogs showed a contrasting expression in S. tuberosum and S. commersonii following cold stress and virus infection. By contrast, no change in RDR transcript activity was detected following both stresses. Overall, this study provides the first comparative genomic analysis of the core components of the RNAi machinery in Solanaceae and offers a scaffold for future functional analysis of these gene families.

The Wild Side of Potato: Insights into the Genome Sequence of the Stress-Tolerant S. commersonii

Solanum commersonii is a potato species native to Central and South America. Despite being genetically isolated from cultivated potato, in the past few years it has garnered significant research interest because it exhibits high tolerance to both biotic and abiotic stresses. Among the abiotic stresses, particularly interesting are its freezing tolerance and capacity to cold acclimatize. Little is understood of the genetic determinants and mechanisms beyond its resistance traits. This is partially due to the lack of genomic resources for potato germplasm. The group at the University of Naples has recently decoded, for the first time, the genome of S. commersonii, ushering in a new era of whole-genome sequencing of wild potato relatives. After illustrating the genome structure and organization of this species and its intriguing evolutionary roots, this chapter describes findings relative to the identification of the candidate genes for cold stress tolerance. The genome sequence of S. commersonii will pave the way to an understanding of the molecular dynamics that have given this species so many adaptive characteristics.

The Majorana mystery

For years after I first learned about Ettore Majorana, I wanted to write a book about his life... but I always deferred to an uncertain future the act of putting pen to paper. Then, one day I read a newspaper clipping and realized that the mystery was about to come full circle. Ettore had just turned one hundred, and a major discovery had been made in the deep waters near Catania. The time had arrived for the final unveiling of the Majorana legacy.

Volumetto II: 23 April 1928

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