Biomedical subjects

A Merighi

Publications and source records attributed to A Merighi.

57 records · Page 4Linked to original sources

PubMed1986

The relationship between lipofuscin and neuromelanin in some sites of the nervous system of the horse.

Histochemical and cytochemical features of neuronal pigment in the spinal cord, and in the sympathetic and spinal ganglia of the adult horse have been studied. Light and electron microscopical observations revealed that lipofuscin pigment is present in the spinal ganglia and in the spinal cord, whereas in the sympathetic ganglia both lipofuscin and neuromelanin are present. The ultrastructural studies showed that lipofuscin granules exhibited a triphasic organization consisting of a matrix, a system of lamellae and one or more lipid vacuoles. Neuromelanin granules have structural features in common with lipofuscin-like granules, except the former types store a highly electron dense material on their matrix. The electron dense material has been identified as melanin by a modification of the Lillie ferrous sulfate reaction applied at the ultrastructural level. From the ultrastructural appearance and cytochemistry of the neuronal pigments in horse it is concluded that neuromelanin should be considered as melanized lipofuscin. The possibility that the different ratio of lipofuscin to melanin within the same granule is responsible for the peculiar reaction of certain neuromelanin granules to lipophilic dyes, the PAS reaction, a histochemical assay for melanin and exposure to ultraviolet light, is discussed.

Animals↗

PubMed1985

Histochemical and ultrastructural features of neuronal pigment in some encephalic nuclei of ruminants.

Neuronal pigment in red nucleus, locus coeruleus and substantia nigra from cattle, sheep and goat was examined with the aid of light and electron microscopy. In the red nucleus and locus coeruleus neurons of all the species examined the pigment shows the histochemical and ultrastructural features typical of lipofuscins. The ultrastructural observations indicated that the morphology of pigment granules is related to age and permitted identification of various stages of pigment evolution, which suggested a lysosomal origin of the pigment bodies. In bovine and sheep the substantia nigra is very reduced and contains no detectable pigment; while in goat, some neurons appear to contain discrete amounts of neuromelanin. Ultrastructurally this kind of pigment appears characterized by the features of a lipofuscin-like granule which stores highly electron dense material identifiable as melanin.

Age Factors↗

PubMedDate not supplied

A prospective study of the ability of three endoscopic classifications to predict hemorrhage from esophageal varices.

Hemorrhage from esophageal varices in cirrhotics is a frequent event with high mortality in spite of therapy. Preventive sclerotherapy seems to be beneficial only if the patient's bleeding risk is higher than 40 to 50% a year. A series of 320 patients with esophageal varices without previous bleeding was studied prospectively; the varices were classified according to three widely used endoscopic classifications. During follow-up (6 to 36 months, average 14 months), hemorrhage occurred in 49 patients (15.3%) of whom 30 (61.2%) bled from varices (8.2 and 11.0% at 12 and 24 months, respectively). At the same time intervals, mortality of the entire population studied was 18.0 and 23.8%, respectively, of which one third was directly due to hemorrhage. With all three classifications, the higher the degree of bleeding risk, the greater the actual percentage of hemorrhages recorded; however, it never reached 40% a year. In predicting the bleeding event, Dagradi's classification proved more sensitive than JRSPH or NIEC, but the latter classifications were more specific and assessed a higher predictive value for a positive test. Endoscopic observation probably needs integration with other methods if a reliable bleeding prediction is to be made.

Esophageal and Gastric Varices↗