Aegagropiles are round-shaped conglomerations of Posidonia oceanica debris commonly found along the coasts of the Mediterranean Sea. This study presents a detailed description of the composition of aegagropiles in terms of their internal organisation in different layers (and the orientation of the fibres in these layers), the proportion of constituent elements (fibres and minerals) and the histological (by way of microscopic observations) nature of all of these aegagropiles elements. The aim of this work is to take a detailed interest in the structure of the aegagropiles of Posidonia oceanica and to determine the process that forms them. Aegagropiles are an assemblage of two types of debris from the P. oceanica meadow: (1) plantbased: fibres more or less degraded from P. oceanica shoots (leaves and rhizomes) and ( 2) mineral particles such as silicates and biotic Ca-carbonate debris. On the basis of structural and compositional observations, we proposed an elucidation of the cycle in several phases: initiation of a "roll" by aggregation of litter fibres and sand in the ripple marks, growth, breakdown of the roll into small balls (microbial and mechanical degradation) and export of aegagropiles down (into the abyss) or on to the beaches. Calculations estimate that considering its density of 0.2 g/cm 3 , an aegagropile represents the accumulation of fibres from approximately 25 shoots of P. oceanica.

OBJECTIVES Surgical treatment of infective endocarditis (IE) remains a challenge. The Ross procedure offers the benefit of a living substitute in the aortic position but it is a more complex operation which may lead to increased operative risk. The aim of this study was to assess the safety and late outcomes of the Ross procedure for the treatment of active IE. METHODS From 2000 to 2019, a total of 31 consecutive patients underwent a Ross procedure to treat active IE (mean age 43 ± 12 years, 84% male). All patients were followed up prospectively. Four patients (13%) were intravenous (IV) drug users and 6 patients (19%) had prosthetic IE. The most common infective organism was Streptococcus (58%). Median follow-up was 3.5 (0.9–4.5) years and 100% complete. RESULTS There were no in-hospital deaths. One patient suffered a postoperative stroke (3%) and 1 patient (3%) required reintervention for bleeding. Three patients had a new occurrence endocarditis: 2 patients were limited to the pulmonary homograft and successfully managed with IV antibiotics, whereas 1 IV drug user patient developed concomitant autograft and homograft endocarditis. Overall, cumulative incidence of IE recurrence was 13 ± 8% at 8 years. The cumulative incidence for autograft endocarditis was 5 ± 4% at 8 years. Two patients (6%) died during follow-up, both from drug overdoses. At 8 years, actuarial survival was 88 ± 8%. CONCLUSIONS In selected patients with IE, the Ross procedure is a safe and reasonable alternative with good mid-term outcomes. Freedom from recurrent infection on the pulmonary autograft is excellent, labelporting the notion that a living valve in the aortic position provides good resistance to infection. Nevertheless, in IV drug user patients, pulmonary homograft endocarditis remains a challenge. Continued follow-up is needed to ascertain the long-term benefits of this approach.

No abstract

No abstract