New insights on the spectrophotometric determination of melatonin pK values and melatonin-βCD 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 pK values, in a completely protected aqueous medium, were estimated as 5.777±0.

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.