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Biomedical subjects

C L Balduini

Publications and source records attributed to C L Balduini.

At least 55 records · Page 3Linked to original sources
PubMed1988

Interrelation of platelet aggregation, release reaction and thromboxane A2 production.

Aggregation of platelets, stimulated by different agonists, was inhibited by omitting sample stirring or by preincubation of platelets with a monoclonal antibody against glycoproteins IIb-IIIa or with a pentapeptide containing the sequence Arg-Gly-Asp-Ser. In platelets stimulated by collagen, ADP and epinephrine, the inhibition of aggregation paralleled a reduction of both release reaction and thromboxane A2 formation. When thrombin was the stimulus, ATP release and thromboxane A2 production were unaffected (or only slightly modified) by the inhibition of platelet aggregation. These data add further evidence to the hypothesis that aggregation supports the activation of platelets stimulated by weak agonists.

Adenosine Diphosphate↗
PubMed1988

Effect of GPIIb-IIIa complex ligands on calcium ion movement and cytoskeleton organization in activated platelets.

We studied the influence of the occupancy of the fibrinogen receptor (GP IIb-IIIa complex) on two early aspects of agonist induced platelet activation: the increase of the intracellular Ca2+ concentration and the cytoskeleton reorganization. A monoclonal antibody, a peptide containing the RGD sequence and fibrinogen purified from human plasma were used as GP IIb-IIIa ligands. The obtained results demonstrated that fibrinogen receptor occupancy inhibits Ca2+ movement and cytoskeleton reorganization caused by low thrombin concentration and ADP.

Adenosine Diphosphate↗
PubMed1988

Platelet aggregation in platelet rich plasma and whole blood in 18 patients affected by idiopathic myelofibrosis.

Platelet aggregation in whole blood (WB) and in platelet rich plasma (PRP) was studied in 18 consecutive patients affected by idiopathic myelofibrosis (IM). On the basis of WB studies, 22% of patients were classified as normo-aggregating and 22% as hypo-aggregating, while 55% had spontaneous platelet aggregation (SPA). SPA was observed also when platelets from patients were stirred in the presence of normal erythrocytes, while it never occurred when normal platelets were stirred in the presence of red cells from patients. PRP studies revealed that 33% and 66% of patients were, respectively, hypo- and normo-aggregating. The most frequent abnormality in PRP was represented by defective or absent aggregation response to epinephrine.

Adenosine Diphosphate↗
PubMed1988

The effect of red cells on platelet aggregation: a study with the electronic whole blood aggregometer.

Platelet aggregation was studied in the same platelet rich plasma (PRP) by the simultaneous use of Born's optical method and Cardinal's electronic method. The maximum rate of impedance change (electronic method) correlated well with both the rate and the extent of aggregation as measured by the optical method. The rate of impedance change was therefore the parameter chosen for the study of the effect of red cells on platelet aggregation. Erythrocytes, both at 40 and 60% haematocrit (Hct.), greatly inhibited platelet aggregation induced by ADP and adrenalin, but only minimally affected platelet aggregation induced by collagen.

Electronics↗
PubMed1987

Severe platelet dysfunction in a patient with autoantibodies against membrane glycoproteins IIb-IIIa.

A young women affected by Hodgkin's disease developed chronic autoimmune thrombocytopenic purpura. Splenectomy induced normalization of her platelet count, but hemorrhagic symptoms did not disappear. The patient's platelets did not aggregate in response to collagen and ADP and the IgG fraction of the patient's plasma induced the same defect in normal platelets. The women's IgG recognized glycoproteins IIb and IIIa of normal platelet membranes. Prednisone therapy induced the disappearance of bleeding symptoms and the normalization of platelet aggregation.

Adult↗
PubMed1986

Effect of a monoclonal antibody against GPs IIb-IIIa on platelet aggregation and ATP secretion.

A murine monoclonal antibody against glycoproteins IIb-IIIa of platelet membrane completely abolished platelet aggregation induced by epinephrine, arachidonic acid, and low concentration of collagen and thrombin, but it had only minor inhibitory effects on aggregation induced by ADP, higher amounts of collagen and thrombin, and these agents combined in pairs. The simultaneous studies of aggregation and ATP secretion demonstrated that aggregation plays an essential role in stimulating the platelet-release reaction, except for the thrombin-induced ATP secretion that seems to be largely dependent on fibrinogen binding to platelet surface.

Adenosine Triphosphate↗
PubMed1985

Mechanisms of thrombin-induced modifications of human platelet cytoskeleton.

Thrombin treated with phenylmethanesulphonyl fluoride, like active enzyme, promotes modifications to human platelet cytoskeleton. The removal of active thrombin by hirudin partially reverses this process. Chymotrypsin-treated platelets do not modify their cytoskeleton after thrombin stimulus, but are still able to increase their adhesiveness to collagen. It is concluded that thrombin influences the cytoskeleton and adhesion by non-enzymic mechanisms which may be mediated by different modulators.

Blood Platelets↗
PubMed1985

Thrombin increases the adhesion of washed human platelets to collagen.

Thrombin stimulates the adhesion of washed human platelets to fibrillar collagen. This phenomenon occurs also when platelets, before thrombin stimulation, are resuspended in the presence of prostaglandin E1 to minimize the release reaction. Enzymatic activity of thrombin is not necessary for the enhancement of platelet adhesiveness, since phenylmethylsulphonylfluoride inhibited thrombin is effective in this respect. Detachment of thrombin from thrombin treated platelets by the use of hirudin restores normal platelet adhesiveness to collagen.

Chromatography, Affinity↗
PubMed1984

Castleman's disease with coagulation defect. A case report.

The case of a young man with the plasma cell type of Castleman's disease is described. Beyond the well known systemic manifestations the coagulation tests showed a decrease in the activity of factors V, VIII and X due to the presence of lupus-like circulating anticoagulants. After surgical excision of the mediastinal mass both hematochemical pathological data and the coagulation defect disappeared. It is suggested that the lupus-like anticoagulant was secreted by the tumor.

Adult↗
PubMed1984

The role of plasma fibronectin in platelet adhesion to collagen.

Human washed platelets were eluted from columns of Sepharose 4B linked to different preparations of collagen in order to evaluate cell adhesion. Collagen preparations characterized by low and high affinity toward platelets were identified. In our experiments, fibronectin purified from human plasma modified platelet adhesiveness, though not dramatically. When washed platelets, resuspended in a buffer containing fibronectin, were filtered on a low-affinity collagen-Sepharose, a significant increase in their adhesion occurred. A similar modification could be observed when platelets were allowed to adhere to the same collagen-Sepharose preconditioned with fibronectin. The effect of fibronectin was otherwise negligible when the high-affinity collagen was used for the experiments.

Chromatography, Affinity↗
PubMed1982

Anomalous erythrocytes produced by rabbits with liver damage.

Rabbit "stress macroreticulocytes" complete their membrane sialic acid content after a short "homing" in the liver. Since also normal rabbit reticulocytes are characterized by a low membrane sialic acid, the role of the liver in the maturation of these cells was investigated. For this purpose red cell modifications consequent to a severe liver steatosis, induced in rabbits by a diet lacking choline, were investigated. Animals with liver damage showed severe anemia and red cell membranes were demonstrated to have a low sialic acid content. Moreover rabbits with severe fatty liver, unlike normal animals, were not able to restore the viability of desialylated normal young erythrocytes. On the basis of these and others evidences we suggest that rabbit liver plays an important role in physiological maturation of reticulocytes.

Animals↗
PubMed1981

Ageing of rabbit red cells in vitro: membrane modifications and their possible role in red cell survival in vivo.

In vitro incubation induces, in rabbit red cell membranes, significant modifications consisting mainly in a decrease of sialic acid and galactose. In vivo the life span of incubated erythrocytes seems to be correlated to the degree of surface alterations and ATP depletion: larger surface modifications and energy charge reduction induce shorter survival time. It can therefore be postulated that incubation of red cell in vitro can cause an ageing process similar to that occurring physiologically in vivo.

Adenosine Triphosphate↗