For the survival of the neonate, the onset of prompt and effective respiration is extremely important, and for this to occur the lungs have to be mature both from the biochemical and from the morphological point of view. If the lungs are not mature, after the first respiratory movements alveoli will tend to collapse rather than remain expanded, thus at each inspi- ration these have to be reopened against the forces of surface tension, which in turn can rapidly cause exhaustation and anoxia in the neonate (Cosmi, 2001). Such neonates de- velop “neonatal respiratory distress syndrome” (NRDS), typical of the premature child and recognised as the main cause of neonatal morbidity and mortality in developed countries. This syndrome is caused by a deficiency in lung surfactant, the substance which forms a superficial limiting layer in the alveoli able to counteract surface tension and thus prevent collapse and transudation (Cosmi, 2001). NRDS has been described also in species other than man, such as bovine (Eigemmann et al., 1984), canine (Manktelow and Baskerville, 1972) and equine (Rossdale et al., 1967). As fetal breathing movements favour the passage of fetal pulmonary liquid into the amniotic fluid (AF), this fluid, collected by amniocentesis or at parturition, is used in human medicine for the evaluation of lung maturity. For long time the reference-test has been the evaluation of the lecithin/sphingomyelin (L/S) ratio, today the evaluation of the concentrations of lamellar bodies (LB) is widely used as it is considered an objective estimation of the amount of surfactant in the amniotic fluid (AF). Lamellar bodies, almost exclusively made up of phospholipids, are the storage form of surfactant, and are produced by type II pneumocytes in increasing quantity as gestation 203 204 progresses (Oulton et al., 1986; Pattle, 1975). As LB are of platelet-like dimensions, they can be simply quantified using a blood cell counter (Dubin, 1989). In human medicine, although with variations between different laboratories, a L/S ratio higher than 2.5, and over 20,000–30,000 LB/μl in centrifuged AF, are considered indicators of lung maturity (Piazze et al., 1999). The aim of this study was to evaluate LB concentration and the L/S ratio in AF collected during at term births of healthy and mature foals.
|Autori:||Rota A; Crisci A; Maranghi L; Tozzi C; Tarantino C; Marmorini P; Sgorbini M; Vannozzi I; Camillo F|
|Titolo:||Concentration of lamellar bodies and the lecithin/sphingomyelin ratio in equine amniotic fluid at the time of delivery|
|Anno del prodotto:||2006|
|Digital Object Identifier (DOI):||10.1007/s11259-006-0041-9|
|Appare nelle tipologie:||1.1 Articolo in rivista|