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Biomedical subjects

A Zanetti

Publications and source records attributed to A Zanetti.

At least 73 records · Page 4Linked to original sources
PubMed1986

Effects of dipyridamole and low-dose aspirin therapy on platelet adhesion to vascular subendothelium.

The effect on platelet function of low-dose aspirin (ASA) and dipyridamole alone or in combination was evaluated after repeated dosing in 5 healthy volunteers. The subjects were treated according to a randomized, single-blind, crossover design with 150 mg of dipyridamole, 25 mg of ASA, the 2 drugs together or placebo twice a day for 3 days. Platelet adhesin was evaluated using an experimental model of adhesion to rat aorta subendothelium under controlled hemodynamic conditions in the presence of red blood cells. Dipyridamole significantly reduced platelet adhesion both alone and in combination with ASA. ASA by itself did not significantly modify platelet adhesion, but completely blocked serum thromboxane production and platelet aggregation by arachidonic acid. Thus, low-dose ASA and dipyridamole may have a complementary action, modifying at the same time 2 platelet functions, adhesion and aggregation, both relevant in the pathogenesis of thrombosis.

Adult↗
PubMed1986

The effect of AD6 (8-monochloro-3-beta-diethylamino-ethyl-4-methyl-7-ethoxy- carbonylmethoxycoumarin) on washed human platelet aggregation induced by platelet activating factor (PAF) and epinephrine.

The effect of AD6 (8-monochloro-3-beta-diethylamino-ethyl-4-methyl-7- ethoxycarbonylmethoxycoumarin) was studied in vitro on washed human platelet aggregation and beta-thromboglobulin (beta TG) release induced by PAF alone or in combination with epinephrine. AD6 caused concentration-dependent inhibition of aggregation and beta TG release. Acetylsalicylic acid and the ADP scavenger apyrase were ineffective on the same parameters, while the specific PAF antagonist CV 3988, the Ca2+ antagonist diltiazem and the cyclo-oxygenase-lipoxygenase inhibitors nordihydroguaiaretic acid and BW 755C inhibited aggregation. The results indicate that AD6 is an inhibitor of platelet aggregation in vitro with a mode of action different from cyclo-oxygenase blockade.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1986

Action of AD6 (8-monochloro-3-beta-diethylaminoethyl-4-methyl-7-ethoxycarbonylmet hox y coumarin) on human platelets in vitro.

The action of AD6 was tested in vitro on human platelets by measuring beta-thromboglobulin (BTG), platelet factor 4 (PF4) and thromboxane B2 (TXB2) release as well as aggregation. BTG and PF4 release from blood anticoagulated with sodium citrate was inhibited by AD6 during a 3 h incubation. Platelet rich plasma (PRP) was stimulated with ADP, collagen, sodium arachidonate, PAF, A23187 and epinephrine, while resuspended washed platelets (WP) were stimulated by thrombin. AD6 (5-100 microM) inhibited dose dependently aggregation, BTG, PF4 and TXB2 release induced by threshold concentration of all the tested aggregating agents; however AD6 action could be overcome by increasing the concentration of the stimulating agents. After cyclo-oxygenase blockade by acetylsalicylic acid (ASA), PRP was stimulated by a supramaximal concentration of PAF. Under these circumstances we could observe a reversible aggregation and a partial release of BTG and PF4, AD6 was able to further reduce aggregation and release. Cyclic AMP accumulation induced in WP by prostacyclin was not modified by AD6 (100 microM), while theophylline greatly potentiated prostacyclin action. We conclude that AD6 is an inhibitor of platelet activation in vitro. Its mode of action is different from cyclo-oxygenase blockade and provides inhibition of platelet activation by a number of different stimuli.

Anticoagulants↗
PubMed1985

Clinical significance of antibody to the hepatitis delta virus in symptomless HBsAg carriers.

Antibody to the hepatitis delta virus (anti-delta) was detected in 112 out of 2487 (5%) individuals fortuitously found to have the hepatitis B surface antigen (HBsAg) in the blood. Liver function was impaired in 38% (43 of 112) of the anti-delta-positive carriers but in only 9% (215 of 2375) of the anti-delta-negative subjects (p less than 0.001). Liver biopsy specimens were obtained from 31 antibody-positive and 97 antibody-negative subjects with impaired liver function. Important histological changes were observed in 61% of the 31 antibody-positive carriers (7 chronic active hepatitis, 4 active cirrhosis, 8 inactive cirrhosis) but in only 19% of the 97 antibody-negative carriers (p less than 0.001). The presence of anti-delta in serum identifies a subpopulation of apparently healthy HBsAg carriers whose risk of underlying liver disease is four times higher than that in the ordinary carrier. The identification of anti-delta in a symptom-free HBsAg carrier with abnormal liver function is thus an indication for a diagnostic liver biopsy.

Antibodies, Viral↗
PubMed1985

Epidemiology of hepatitis delta virus (HDV) infection.

Markers of hepatitis delta virus (HDV) infection have been detected all over the five continents. Geographical prevalence varied heavily: HDV infection is very rare in Far East Asia, but extremely frequent in Arabian countries, in Romania and in certain Indian populations of South America. In Europe and in the USA the infection is widely spread among high risk groups such as intravenous drug abusers and haemophiliacs.

Africa↗
PubMed1985

Human platelet adhesion to subendothelium under controlled hemodynamic conditions: a methodological approach.

A rotating probe device was used to quantitate platelet adhesion to rat aorta subendothelial surface. Platelet adhesion increased in relation to the time of exposure to the subendothelial surface, the shear rate, the percentage of hematocrit and the number of platelets in the suspending media. Human umbilical arteries or collagen-coated glass can be used as adhesion surfaces with results similar to those obtained with rat aorta subendothelium. Platelet-rich plasma or washed platelets can be used in this system with comparable results. The test is sensitive to a series of antiaggregating agents and could be used in clinical studies of platelet adhesion defect.

Animals↗
PubMed1982

[Ultrastructural studies of tissue surrounding endosseous dental implants].

We have observed peri-implant tissue specimens of endosseus dental implants subjected or not to occlusal load. All the specimens showed a large network of collagen microfibrils and proteoglycans filaments, strictly adherent to the endoprothesis. In some cases a layer of connective tissue surrounds the proteoglycan network only in some peri-implant areas. Cellular and extracellular components of this connective tissue were orientated parallel to the metal surface and all this appears to be correlated to a definite biological function.

Collagen↗
PubMed1981

Infection with the delta agent in chronic HBsAg carriers.

To establish the mechanism of progression to chronicity of the HBsAg-associated delta infection, serum hepatitis B virus and delta markers were tested in five babies born to HBsAg-positive mothers with anti-delta, in 42 follow-up patients with acute hepatitis B virus and delta hepatitis, and in collections of sera from 8 HBsAg carriers with anti-delta. Evidence of delta infection was found in the baby born to a mother with serum HBeAg and in none of the four babies born to mothers with anti-HBe. Hepatitis was self-limited in the 42 patients acutely infected by hepatitis B virus and delta agent; none developed persistent HBs-antigenemia and the majority displayed transient anti-delta of IgM class. In seven HBsAg carriers high titers of anti-delta developed during the follow-up; coincident with the rise of the antibody, aminotransferase elevation occurred in five previously asymptomatic carriers and persisted in three of them. No sign of infectious hepatitis B virus replication was detected in five of the carriers throughout the follow-up, and all of them had anti-HBe before the rise of anti-delta and of aminotransferase. HBsAg carriers with diminished hepatitis B virus synthesis appear to be at high risk of developing chronic delta infection and disease when exposed to the delta-infectious serum of other carriers.

Adult↗
PubMed1975

[Unusual aspects of bone fractures in Paget's disease].

Because of their specific biological and vascular condition, bones affected by Paget's disease require special treatment in case of fracture. Observations on four patients are reported because of their originality; the two first involved a rare type of pelvic fracture, one ischiatic, the other iliac. One of the others was a deformation that required amputation. The last patient, a victim of a diaphyseal femoral fracture, had to undergo centromedullary pinning; but because there was massive destruction of the periostial and medullary circulations during the operation, extensive osteonecrosis due to ischaemia occurred which was very painful and disabling. Thus, in spite of an over abundance of vascular tissue, such circulatory repercussions must be avoided in surgical treatment of fractures of bones affected by Paget's disease.

Aged↗