RESUMEN
Platelet function is developmentally regulated. Healthy neonates do not spontaneously bleed, but their platelets are hypo-reactive to several agonists. The mechanisms underlying immature platelet function in neonates are incompletely understood. This critical issue remains challenging for the establishment of age-specific reference ranges. In this study, we evaluated platelet reactivity of five pediatric age categories, ranging from healthy full-term neonates up to adolescents (11-18 years) in comparison to healthy adults (>18 years) by flow cytometry. We confirmed that platelet hypo-reactivity detected by fibrinogen binding, P-selectin, and CD63 surface expression was most pronounced in neonates compared to other pediatric age groups. However, maturation of platelet responsiveness varied with age, agonist, and activation marker. In contrast to TRAP and ADP, collagen-induced platelet activation was nearly absent in neonates. Granule secretion markedly remained impaired at least up to 10 years of age compared to adults. We show for the first time that neonatal platelets are deficient in thrombospondin-1, and exogenous platelet-derived thrombospondin-1 allows platelet responsiveness to collagen. Platelets from all pediatric age groups normally responded to the C-terminal thrombospondin-1 peptide RFYVVMWK. Thus, thrombospondin-1 deficiency of neonatal platelets might contribute to the relatively impaired response to collagen, and platelet-derived thrombospondin-1 may control distinct collagen-induced platelet responses.
Asunto(s)
Envejecimiento/fisiología , Plaquetas/metabolismo , Colágeno/farmacología , Trombospondina 1/farmacología , Adenosina Difosfato/farmacología , Adolescente , Adulto , Plaquetas/efectos de los fármacos , Niño , Venenos de Crotálidos/farmacología , Exocitosis/efectos de los fármacos , Humanos , Lactante , Recién Nacido , Lectinas Tipo C , Péptidos/farmacología , Activación Plaquetaria/efectos de los fármacos , Receptores Proteinasa-Activados/metabolismo , Trombospondina 1/químicaAsunto(s)
Glomerulonefritis Membranoproliferativa/diagnóstico , Lesión Renal Aguda/sangre , Lesión Renal Aguda/etiología , Anciano , Anticuerpos Anticitoplasma de Neutrófilos/sangre , Infecciones por Bartonella/sangre , Infecciones por Bartonella/complicaciones , Complemento C3/análisis , Complemento C4/análisis , Endocarditis Bacteriana/sangre , Endocarditis Bacteriana/complicaciones , Glomerulonefritis Membranoproliferativa/sangre , Glomerulonefritis Membranoproliferativa/complicaciones , Glomerulonefritis Membranoproliferativa/microbiología , Hematuria/sangre , Hematuria/etiología , Humanos , MasculinoRESUMEN
We describe the case of a 33 year old man with Tricho-Rhino-Phalangeal Syndrome (TRPS) and mitral valve disease. Tricho-Rhino-Phalangeal Syndrome is a rare multisystem disorder. The English literature has no record of any association with mitral valve disease which was a feature of our patient and his father both of whom were suffering from the syndrome. Doctors looking after patients with that condition should be alert to this possible association.
