New insights on the spectrophotometric determination of melatonin pKa values and melatonin-ßCD inclusion complex formation constant.

Using UV-Vis spectrophotometry a stability study of melatonin at different pH values was done in aqueous media, finding that at acidic pH melatonin is unstable when interacting with the environment, however it becomes stable protecting it from light and oxygen. From the UV-Vis spectra and SQUAD software, melatonin pKa values, in a completely protected aqueous medium, were estimated as 5.777±0.011 and 10.201±0.024. Using the same techniques, the melatonin and ß-cyclodextrin inclusion complex formation constants were assessed at pH3, 7 and 11.5, giving the values of log ß=(3.07±0.06), (2.94±0.01) and (3.07±0.06) M-1, respectively. From the global acidity formation constants and the complexes' formation constants, the molar fractions were determined for each species of MT and MT-ßCD, to build the molar fraction-[ßCD]-pH 3D diagram and the molar fraction-pH 2D diagrams, where it was possible to observe the predominance of the MT species with and without ßCD. A voltammetric study at pH3, allowed obtaining a value of log ß=(3.15±0.01) M-1, which corroborates that obtained through UV-Vis spectrophotometry, supporting strongly the rationale behind using simple, straightforward techniques.

Persistent and redundant eustachian valve simulating atrial tumor: prenatal diagnosis.

The eustachian valve, or valve of the inferior vena cava, is an embryogenic derivative of the right valve of the sinus venosus. Although it generally disappears during fetal life, its persistence may simulate symptoms of cardiac disease, particularly those associated with atrial tumors. We describe a case of prenatal diagnosis of a persistent, large and prominent eustachian valve with redundant tissue attached to the junction of the inferior vena cava and the right atrium. The neonate was asymptomatic and was healthy at 7 months of age at the time of writing. This is the first time that this finding has been diagnosed prenatally.

Diagnóstico prenatal de un caso de nefrona mesoblástico congénito y revisión bibliográfica / Prenatal diagnosis of congenital mesoblastic nephorma. A case report and bibliographic review

Reportar un nuevo caso de diagnóstico prenatal de una entidad infrecuente (el 27 de los publicados) puede contribuir a establecer mejores estrategias diagnósticas y de manejo. Se establece un diagnóstico de nefroma mesoblástico congénito a las 31 semanas de gestación ante los hallazgos ecográficos de tumor renal sólido y polihidramnios. Se mantuvo conducta expectante con controles ambulatorios frecuentes. Las pruebas de bienestar fetal fueron correctas, el tamaño tumoral no se modificó y fue preciso una amniocentesis evacuadora, manteniéndose luego el volumen de líquido amniótico estable. A las 37 semanas se induce el parto y nace un feto varón por vía vaginal con buena vitalidad. Tras estudios neonatales, al octavo día se le practica nefrectomía y el estudio histológico confirma un nefroma mesoblástico congénito. Tras 1 año el niño sigue sano. El manejo antenatal del nefroma mesoblástico debe dirigirse al control del polihidramnios y sus complicaciones (parto prematuro y rotura prematura de membranas), así como al manejo atraumático del recién nacido para evitar la rotura tumoral. Dado que generalmente se trata de tumores benignos y no se asocian otras anomalías, el pronóstico es bueno con la nefrectomía neonatal (AU)

To report on a new case of prenatal diagnosis of an uncommon disease entity (the 27th reported case) to contribute to establishing better diagnostic and therapeutic strategies. A mesoblastic nephroma was diagnosed at 31 weeks of pregnancy based on ultrasound finding of a solid renal tumor and polyhydramnios. A wait and see attitude was adopted with frequent outpatient check-ups; the tests of fetal well-being were correct, tumor size remained unchanged, and amnioreduction by amniocentesis was required, although the volume of amniotic fluid remained stable thereafter. Labor was induced at 37 weeks and a male fetus was delivered vaginally, with good vitality. Following neonatal studies, nephrectomy was performed on day 8. The histological study confirmed that it was a congenital mesoblastic nephroma. One year later, the patient remains healthy. Antenatal management of mesoblastic nephroma should be aimed at controlling polyhydramnios and its complications (premature labor and premature membrane rupture), as well as non-traumatic handling of the newborn infant to avoid rupturing the tumor. Neonatal nephrectomy leads to good prognosis, since congenital mesoblastic nephroma is generally a benign tumor and is not associated with other anomalies (AU)