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Mitral valve replacement in infants is challenging and there are limited alternative valves available. Since the Boston group published their first report on alternative valves for mitral valve replacement in infants, there has been a growth in the literature on the topic, mostly based on the use of a stented bovine jugular vein graft (Melody® valve). The challenges of the Melody valve are firstly in its length of 28 mm unexpanded, which has the potential to cause left ventricular outflow tract obstruction, and secondly, the valve needs mechanical dilatation, which is laborious. A modified No-React® Injectable Biopulmonic™ Prosthesis (Bio Integral Surgical, Inc., Mississauga, ON, Canada) which is shorter (19 mm) and simpler in that it is self-expanding was implanted in a 14-month-old child to replace her mitral valve. The operation was successful and the short-term function of the prosthesis is good.

Acute myocarditis leading to severe heart failure in paediatric patients is an uncommon but potentially life-threatening condition. The prompt implant of mechanical circulatory devices such as veno-arterial extra-corporeal membrane oxygenation remains the best treatment option to restore an adequate perfusion and improve patient survival in case of refractory cardiogenic shock cases. While few reports describe the in-hospital course of this dramatic disease, with an in-hospital mortality under veno-arterial extra-corporeal membrane oxygenation support around 30%, our study aims to analyse both short- and long-term outcomes after extra-corporeal membrane oxygenation implant.

Dextro-transposition of the great arteries with intact ventricular septum (d-TGA) is the most frequent cyanotic congenital heart disease in neonates. In newborns affected by d-TGA, the pulmonary and systemic circulations are in parallel instead of being in series. The survival of babies affected by d-TGA is related to the level of mixing at the patent foramen ovale. The diagnosis of d-TGA is an indication for treatment due to scarce survival beyond the neonatal period if not corrected. The current surgical approach is the anatomical correction with the arterial switch operation, which has excellent early and medium-term results. In this review, we discuss treatment of d-TGA and the arterial switch operation, the medium- and long-term results following surgery, and the reasons that have led the arterial switch operation to its popularity compared to the former physiological correction of d-TGA, i.e. the Senning and Mustard procedures.

Dextro-transposition of the great arteries with intact ventricular septum (d-TGA) is the most frequent cyanotic congenital heart disease in neonates. In newborns affected by d-TGA, the pulmonary and systemic circulations are in parallel instead of being in series. The survival of babies affected by d-TGA is related to the level of mixing at the patent foramen ovale. The diagnosis of d-TGA is an indication for treatment due to scarce survival beyond the neonatal period if not corrected. The current surgical approach is the anatomical correction with the arterial switch operation, which has excellent early and medium-term results. In this review, we discuss treatment of d-TGA and the arterial switch operation, the medium- and long-term results following surgery, and the reasons that have led the arterial switch operation to its popularity compared to the former physiological correction of d-TGA, i.e. the Senning and Mustard procedures.

La trasposizione delle grandi arterie (TGA) è la più frequente cardiopatia cianotica congenita nei neonati. Nei neonati portatori di TGA, le circolazioni polmonare e sistemica sono in parallelo invece che in serie. La sopravvivenza dei bambini portatori di TGA è correlata al livello di mixing ematico attraverso il forame ovale pervio. La storia naturale della trasposizione ha un’evoluzione progressiva e infausta e ne giustifica l’indicazione al trattamento chirurgico. L’attuale approccio chirurgico prevede una correzione anatomica con l’intervento di switch arterioso, che oggi garantisce ottimi risultati a breve e medio termine.

Background Transposable elements (TEs) can represent one of the major sources of genomic variation across eukaryotes, providing novel raw materials for species diversification and innovation. While considerable effort has been made to study their evolutionary dynamics across multiple animal clades, molluscs represent a substantially understudied phylum. Here, we take advantage of the recent increase in mollusc genomic resources and adopt an automated TE annotation pipeline combined with a phylogenetic tree-based classification, as well as extensive manual curation efforts, to characterize TE repertories across 27 bivalve genomes with a particular emphasis on DDE/D class II elements, long interspersed nuclear elements (LINEs), and their evolutionary dynamics. Results We found class I elements as highly dominant in bivalve genomes, with LINE elements, despite less represented in terms of copy number per genome, being the most common retroposon group covering up to 10% of their genome. We mined 86,488 reverse transcriptases (RVT) containing LINE coming from 12 clades distributed across all known superfamilies and 14,275 class II DDE/D-containing transposons coming from 16 distinct superfamilies. We uncovered a previously underestimated rich and diverse bivalve ancestral transposon complement that could be traced back to their most recent common ancestor that lived ~ 500 Mya. Moreover, we identified multiple instances of lineage-specific emergence and loss of different LINEs and DDE/D lineages with the interesting cases of CR1- Zenon, Proto2, RTE-X, and Academ elements that underwent a bivalve-specific amplification likely associated with their diversification. Finally, we found that this LINE diversity is maintained in extant species by an equally diverse set of long-living and potentially active elements, as suggested by their evolutionary history and transcription profiles in both male and female gonads. Conclusions We found that bivalves host an exceptional diversity of transposons compared to other molluscs. Their LINE complement could mainly follow a “stealth drivers” model of evolution where multiple and diversified families are able to survive and co-exist for a long period of time in the host genome, potentially shaping both recent and early phases of bivalve genome evolution and diversification. Overall, we provide not only the first comparative study of TE evolutionary dynamics in a large but understudied phylum such as Mollusca, but also a reference library for ORF-containing class II DDE/D and LINE elements, which represents an important genomic resource for their identification and characterization in novel genomes.

Heteroplasmy is the presence of more than one type of mitochondrial genome within an individual, a condition commonly reported as unfavorable and affecting mitonuclear interactions. So far, no study has investigated heteroplasmy at protein level, and whether it occurs within tissues, cells, or even organelles. The only known evolutionarily stable and natural heteroplasmic system in Metazoa is the Doubly Uniparental Inheritance (DUI)—reported so far in ∼100 bivalve species—in which two mitochondrial lineages are present: one transmitted through eggs (F-type) and the other through sperm (M-type). Because of such segregation, mitochondrial oxidative phosphorylation proteins reach a high amino acid sequence divergence (up to 52%) between the two lineages in the same species. Natural heteroplasmy coupled with high sequence divergence between F- and M-type proteins provides a unique opportunity to study their expression and assess the level and extent of heteroplasmy. Here, for the first time, we immunolocalized F- and M-type variants of three mitochondrially-encoded proteins in the DUI species Ruditapes philippinarum, in germline and somatic tissues at different developmental stages. We found heteroplasmy at organelle level in undifferentiated germ cells of both sexes, and in male soma, whereas gametes were homoplasmic: eggs for the F-type and sperm for the M-type. Thus, during gametogenesis, only the sex-specific mitochondrial variant is maintained, likely due to a process of meiotic drive. We examine the implications of our results for DUI proposing a revised model, and we discuss interactions of mitochondria with germ plasm and their role in germline development. Molecular and phylogenetic evidence suggests that DUI evolved from the common Strictly Maternal Inheritance, so the two systems likely share the same underlying molecular mechanism, making DUI a useful system for studying mitochondrial biology.

Germ line segregation can occur during embryogenesis or after embryogenesis completion, with multipotent cells able to give rise to both germ and somatic cells in the developing juvenile or even in adulthood. These undifferentiated cells, in some animals, are self-renewing stem cells. In all these cell lineages, the same set of genes, among which vasa , appears to be expressed. We traced VASA expression during the peculiar gonad rebuilding of bivalves to verify its presence from undifferentiated germ cells to mature gametes in an animal taxon in which the mechanism of germ line establishment is still under investigation. We utilized antibodies produced against VASPH, VASA homolog of Ruditapes philippinarum (Subclass Heterodonta), to compare the known expression pattern of R. philippinarum to two species of the Subclass Pteriomorphia, Anadara kagoshimensis and Crassostrea gigas , and another species of the Subclass Heterodonta, Mya arenaria . The immunohistological data obtained support a conserved mechanism of proliferation of “primordial stem cells” among the simple columnar epithelium of the gut, as well as in the connective tissue, contributing to the seasonal gonad reconstitution. Given the taxonomic separation of the analyzed species, we suggest that the process could be shared in bivalve molluscs. The presence of germ cell precursors in the gut epithelium appears to be a feature in common with model organisms, such as mouse, fruit fly, and human. Thus, the comparative study of germ line establishment can add details on bivalve development, but can also help to clarify the role that VASA plays during germ cell specification.