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Biomedical subjects

M Giordani

Publications and source records attributed to M Giordani.

12 recordsLinked to original sources
PubMed1991

Hydrogen peroxide is an intermediate in the platelet activation cascade triggered by collagen, but not by thrombin.

Human blood platelets produce oxidant species when stimulated by collagen and thrombin. The oxidative burst of platelets has been studied by cytofluorimetry taking advantage of the fluorogenic dye DCFH2-DA, which is taken up and deacetylated by platelets and then oxidized to the fluorescent derivative DCF. The oxidation of DCFH2 is induced by stimulation with collagen but not with thrombin and inhibited by external catalase. Catalase also inhibited the aggregation induced by collagen, but not that induced by thrombin. Aspirin and indomethacin inhibited the formation of the fluorochrome only when platelets were stimulated by thrombin. Externally added H2O2 increased the cytoplasmic calcium content as probed by the fluorescence of Indo-1. The present data suggest that collagen induces the production of H2O2, which in turn may stimulate the aggregation of platelets through a calcium mobilization. Instead the stimulation by thrombin does not require the intermediacy of H2O2.

Aspirin↗
PubMed1990

Stimulated platelets release factor(s) affecting the in vitro response of human polymorphonuclear cells.

The metabolic and functional responses of human polymorphonuclear cells (PMNs) to thrombin-activated platelet supernatants were studied. The incubation of PMNs with supernatants from stimulated platelets (SPS) caused a 50% decrease in both killing of Staphylococcus aureus and luminol-enhanced chemiluminescence (CL) by PMNs stimulated by opsonized-zymosan (OZ), Concanavalin A (Con A), or calcium ionophore A23187. The levels of PMN intracellular fluorescence measured by flow cytometry, using the fluorochrome dichlorofluorescein diacetate (DCF-DA), were considerably less in the presence of SPS than in resting platelet supernatants (RPS). No influence of platelet supernatant on O2 consumption and O2- generation by OZ-activated PMNs was observed. The incubation of PMNs with SPS caused a significant increase in the rate of chemotaxis and aggregation elicited by Con A, OZ, and phorbol myristate acetate (PMA). The supernatant from resting platelets did not show any of the above-reported effects. Platelets previously degranulated by thrombin were unable to inhibit CL when activated with agonists. Studies on the differential release of the granules by platelets showed that the CL-quenching activity paralleled the discharge of lysosomal content. The release of myeloperoxidase (MPO) from PMNs elicited by OZ was reduced in the presence of SPS. The platelet supernatant did not affect the MPO activity if PMNs were lysed with Triton X-100. The leakage of lactate dehydrogenase (LDH) from platelets was less than 3%, and no catalase or superoxide dismutase was released. This activity withstood lyophilization, but was destroyed by 10 min heating at 100 degrees C or by treatment with proteolytic enzymes.

Blood Platelets↗
PubMed1989

Platelet lipid peroxidation in haemodialysis patients: effects of vitamin E supplementation.

In haemodialysis patients, increased concentrations of malonyldialdehyde and decreased vitamin E content indicate lipid peroxidation in the platelets from oxidative damage. The same process has been described in red blood cells and in mononuclear cells in peripheral blood. However, platelet aggregation is within normal limits and does not change after treatment with vitamin E. On the other hand vitamin E supplementation reverts completely the biochemical abnormality of the platelets.

Blood Platelets↗
PubMed1987

Selective tarsal arthrodesis: an in vitro analysis of the effect on foot motion.

Five different intertarsal arthrodeses were simulated in 15 fresh cadaver feet/ankles utilizing external fixation. Pin placement was verified radiographically. Range of motion measurements were performed before pin placement, after pin placement, and after simulated arthrodesis. The deficit in foot motion created by selected limited intertarsal fusions was then measured. The prearthrodesis range of motion measurements were found to be dorsiflexion (DF), 27 degrees; plantarflexion (PF), 57 degrees; total inversion (INVT), 29 degrees; eversion total (EVT), 22 degrees; hindfoot varus (VRH), 16 degrees; hindfoot valgus (VLH), 12 degrees. The deficits in motion after arthrodesis were as follows. Ankle (tibiotalar): DF, 50.7%; PF, 70.3%; INVT, 8.7%; EVT, 9.4%; VRH, 34.6%; VLH, 27.8%. Hindfoot arthrodesis (Tibiotalar calcaneal): DF, 53%; PF, 71.3%; INVT, 49.5%; EVT, 47.6%, VRH, 100%; VLH, 100%. Pantalar (Tibotalar calcaneal cuboid navicular): DF, 62.8%; PF, 82.2%; INVT, 71.7%; EVT, 67.4%; VRH, 100%; VLH, 100%. Triple (Talocalcaneal cuboid navicular): DF, 12.5%; PF, 15.5%; INVT, 50%; EVT, 51.4%; VRH, 60.5%; VLH, 60.5%. Total tarsal arthrodesis: DF, 78.5%; PF, 90.2%, INVT, 87.5%; EVT, 83.6%; VRH, 100%; VLH, 100%.

Ankle Joint↗
PubMed1985

Treatment of bleeding esophageal varices by portoazygos disconnection and esophageal transection with the button of Boerema and EEA stapler: ten years' experience.

We present 64 patients with bleeding esophageal varices who have been treated with portoazygos disconnection, devascularization of the esophagogastric junction, and esophageal transection with the button of Boerema (32 patients) and EEA stapler (32 patients). The patients were treated between 1973 and 1983. Their ages ranged from 50 to 70 years. Based on Child's classification, 26 (37.5%) of the patients fell into class A, 35 (54.6%) in class B, and five (7.8%) in class C. These patients were also divided into three subgroups: group I--21 patients (32.8%) underwent emergency operations; group II--40 patients (62.5%) underwent semiemergency operations; and group III--three patients (4.7%) underwent elective operations. The perioperative mortality rate was 10.8%. With the Fischer exact test, we found the combined death rate of Child's classes A and B to be significantly lower than that for class C patients. The duration of follow-up ranged from 6 months to 9 years (average 32.9 months) in the 80% of the patients that we were able to follow. There was a 6.5% incidence of recurrent gastrointestinal bleeding and a 28% incidence of late encephalopathy. The incidence of transitory dysphagia was 40% when the button of Boerema was used as compared with 9% when the EEA stapler was used. The surgical approach presented herein is an attractive alternative to portosystemic decompression for patients in whom hepatic dysfunction is complicated by uncontrolled variceal hemorrhage.

Aged↗