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Biomedical subjects

G Ricevuti

Publications and source records attributed to G Ricevuti.

At least 109 records · Page 6Linked to original sources
PubMed1977

In vivo behaviour of neuraminidase-treated rabbit erythrocytes and reticulocytes.

51Cr rabbit erythrocytes were treated with different amount of neuraminidase and reinjected into the animal. The survival curves after the removal of more than 50% membrane sialic acid show a characteristic behaviour: after a rapid decrease, blood radioactivity increases again reaching a maximum level 50-80 h after reinjection, then tends to decrease with a slope similar to that of control curves. Liver radioactivity determined before the rise of blood radioactivity is evidently higher than the value determined after radioactivity elevation. Similar results were obtained with phenylhydrazine-induced young erythrocytes.

Animals↗
PubMed1977

Membrane sialic acid and behaviour in vivo of rabbit "stress" macroreticulocytes.

Membranes of rabbit reticulocytes obtained by phenylhydrazine stimulation have a chemical composition different from that of normal erythrocytes; sialic acid/protein and cholesterol/protein ratios are in fact lower than normal. In vivo study of 51Cr-labelled reticulocytes show that these cells are quickly removed from blood and, after a short "homing" in liver, return to peripheral blood. During "homing" in the liver, the sialic acid/protein ratio seems to increase.

Animals↗
PubMedDate not supplied

Pharmacokinetics of dipyridamole-beta-cyclodextrin complex in healthy volunteers after single and multiple doses.

Dipyridamole is a well known anti-aggregating agent characterized by poor water solubility as well as scant and variable bioavailability. Recently, the compound was complexed with beta-cyclodextrin forming a molecular encapsulation resulting in better oral absorption and stronger biological activities in animals. In the present study, a randomized double blind cross-over comparison between dipyridamole-beta-cyclodextrin complex (dip-beta-CD) and dipyridamole was performed in 12 healthy subjects after single (75mg) and multiple oral treatments (75mg TID). Dip-beta-CD showed better bioavailability and less interindividual variability than dipyridamole either after single or multiple doses. In particular, dip-beta-CD had a greater AUC and Cmax, and a smaller Tmax even at the steady state. In addition, 100% of the subjects receiving a single dose of dip-beta-CD, as compared to 66.7% of those treated with dipyridamole, had plasma levels superior to 1 microgram/ml (which is the supposed anti-aggregating threshold level). In contrast, 0 and 33.03% of the subjects showed plasma levels superior to 2.5 micrograms/ml (which might cause the appearance of side-effects) on the 7th day of the multiple treatment with dip-beta-CD and dipyridamole, respectively. In fact, the subjects presenting higher levels after uncomplexed dipyridamole also complained of headache and/or dizziness on occasion. No adverse side effects were reported for dip-beta-CD.

Administration, Oral↗
PubMedDate not supplied

CD40 ligand-dependent maturation of human monocyte-derived dendritic cells by activated platelets.

Atherosclerosis is defined as an inflammatory immunological disease that is triggered by platelet activation, endothelial injury and consequent innate and adaptive immune processes. Dendritic cells are critical for the cell-mediated arm of the immune response as they activate naïve T cells after maturation. Platelets play a crucial role in thrombus formation in the injured vessel walls. We investigated the role of resting and thrombin-activated platelets in dendritic cell maturation in vitro using platelets and monocyte-derived dendritic cells from healthy donors. Resting platelet supernatants did not affect maturation, whereas supernatants from thrombin-activated platelets induced dendritic cell maturation as demonstrated by FACS analysis of HLA-DR expression. This effect was inhibited by anti CD40 ligand antibody, but not by aspirin pretreatment of platelets. Supernatants of platelet-dendritic cell co-cultures induced augmented monocyte migration when platelets were activated by thrombin, again reversible by blocking CD40 ligand. These data show that activated platelets trigger dendritic cell maturation independent of cyclooxygenase-derived arachidonic acid metabolites by mechanisms involving CD40 ligand, which is also involved in monocyte chemotactic mediator release from platelets and dendritic cells. The results of this study suggest a role of CD40 ligand from activated platelets in connecting innate and adaptive immunity.

Blood Platelets↗