Interaction of echicetin with a high affinity thrombin binding site on platelet glycoprotein GPIb.

Echicetin, a protein isolated from Echis carinatus snake venom, inhibited platelet aggregation and secretion induced by low concentrations of thrombin ( < 0.2 U/ml), by binding to platelet glycoprotein Ib (GPIb). The inhibition was not observed when the platelets were stimulated with higher concentrations of thrombin ( > 0.

Presence of aromatase inhibitors in cycads.

Cycads, the most primitive of the living gymnosperms, have been used and continue to be used for food and medicinal purposes by many cultures, although toxins must be removed before ingestion. In our quest to identify tropical plants that contain inhibitors of the cytochrome P-450 aromatase and thus may be efficacious in treating estrogen-dependent tumors, we have screened extracts from 5 species of cycad folia encompassing 3 genera: Cycas cairnsiana F. Muell.

[Evaluation of serum cortisol concentration in neonates with infections complicated by acute respiratory failure].

In 84 newborns with acute respiratory failure serum cortisol and its changes were evaluated in relation to the cause of the disease, maturity of the neonate and severity of the respiratory insufficiency. Thirty-nine out of the 84 newborns were born prematurely, 51 were suffering from pneumonia, 23 had sepsis. In all the neonates, serum cortisol concentrations were measured three times: on admission, on the fourth day of treatment and during convalescence.

Reversal of heparin anticoagulation by recombinant platelet factor 4 and protamine sulfate in baboons during cardiopulmonary bypass.

The ability of recombinant platelet factor 4 and protamine to neutralize heparin after cardiopulmonary bypass was compared in anesthestized baboons. Clotting titration curves of heparinized baboon blood demonstrate an anticoagulant effect of protamine that is not seen with recombinant platelet factor 4. Neither drug caused meaningful changes in central pressures or cardiac output within 30 minutes after injection.

Iloprost and echistatin protect platelets during simulated extracorporeal circulation.

Temporary, reversible inhibition of platelets during cardiopulmonary bypass is an attractive strategy to protect platelets and normalize postoperative bleeding times. Iloprost, an analogue of prostacyclin, and the disintegrins reversibly inhibit platelets by different mechanisms. We tested the hypothesis that reduced doses of iloprost and either echistatin, a natural disintegrin, or RO43-5054, a peptidomimetic, in combination provide better platelet protection than any drug alone during simulated extracorporeal circulation.

beta-Amyloid protein induces platelet aggregation and supports platelet adhesion.

The amyloid precursor protein (APP) is found in many cells including neurons, endothelial cells and blood platelets. Beta-amyloid protein (beta AP) is derived from APP and is deposited in brain and in cerebral microvasculature of individuals with Alzheimer's disease. In this study we demonstrate that beta AP interacts with human blood platelets.

Preparation of membrane-immobilised enzymes for phenol decomposition.

A method for the preparation of membranes with immobilised enzymes for the biological degradation of phenols is described. In the first stage, an enzymatic fraction from bacterial strains has been isolated. The enzyme membranes were obtained by ultrafiltration of protein solution through a membrane support made of non-cellulose polymers.

Interaction of disintegrins with the alpha IIb beta 3 receptor on resting and activated human platelets.

Viper venom disintegrins contain the RGD/KGD motif. They inhibit platelet aggregation and cell adhesion, but show structural and functional heterogeneity. We investigated the interaction of four prototypic disintegrins with alpha IIb beta 3 expressed on the surface of resting and activated platelets.

Relation of nimodipine dose and serum concentration to learning enhancement in aging rabbits.

Nimodipine, a 1,4-dihydropyridine calcium channel blocker, has been shown to enhance learning in aging rats, rabbits, and monkeys. Using an intravenous drug model, the relations among nimodipine dosage, nimodipine plasma concentration, and acquisition rate of the conditioned eyeblink response in aging rabbits were observed. Animals treated with nimodipine reached a behavioral criterion of 80% conditioned responses more quickly than did vehicle-treated control animals.

Zinc ions potentiate adenosine diphosphate-induced platelet aggregation by activation of protein kinase C.

Zinc deficiency has been linked to a bleeding tendency and impaired wound healing in several disease states. A number of investigators have suggested that zinc ions play a role in platelet aggregation in vitro as well as in in vivo studies. The purpose of the present study was to explore the mechanism by which adenosine diphosphate (ADP) and Zn2+ may act cooperatively during activation of blood platelets.

[Effect of subinhibitory doses of some antibiotics on bacteria in vitro].

The study was aimed at observation of influence of subinhibitory doses of selected beta-lactam antibiotics (cefuroxime, ceftazidime, thienamycin) and of ciprofloxacin on morphology and physiology of S. aureus and E. coli.

Interaction of thrombospondin with platelet glycoproteins GPIa-IIa and GPIIb-IIIa.

The interaction of human thrombospondin (TSP) with GPIa-IIa and GPIIb-IIIa was studied. The binding for both proteins became time-independent after 60 min. A 7-fold excess concentration of unlabelled GPIa-IIa added either initially, or after time-dependent binding, resulted in a 50% inhibition of GPIa-IIa bound to TSP.

Exposure of platelet fibrinogen receptors by zinc ions: role of protein kinase C.

Previous studies demonstrated that Zn2+ at a concentration of 50 microM increases the number of fibrinogen receptors exposed on ADP-stimulated platelets and that higher concentrations of Zn2+ induce platelet aggregation that appears to be mediated by receptors associated with the glycoprotein IIb/IIIa complex. The purpose of this study was to identify the mechanism by which Zn2+ modulates exposure of fibrinogen receptors on the surface of human washed platelets. We determined that Zn2+ (300-800 microM)-induced platelet aggregation that was not accompanied by the release of [14C]serotonin was not blocked by ADP scavenging enzymes and 5'-p-fluorosulfonylbenzoyl-adenosine, an affinity label for ADP binding sites, but it was inhibited by disintegrins, staurosporine, and EDTA.

Beta 3 integrin derived peptide 217-230 inhibits fibrinogen binding and platelet aggregation: significance of RGD sequences and fibrinogen A alpha-chain.

beta 3 Integrin derived peptides 217-230 (DAPEGGFDAIMQAT) and 217-231 (Y) (DAPEGGFDAIMQATVY) at 100 microM inhibited 125I-fibrinogen binding to ADP-stimulated platelets and platelet aggregation. Peptide 217-231 (Y) (100 microM) significantly inhibited the binding of 125I-albolabrin (a disintegrin with a single RGD sequence) to ADP- and thrombin-activated platelets while it had only a slight effect on albolabrin binding to resting platelets. The 125I-beta 3 217-231 (Y) cross-linked selectively to the fibrinogen A alpha-chain.

Functional aspects of calcium-channel modulation.

Associative learning is accompanied by a number of changes in the brain, many mediated by calcium. We have used eyeblink conditioning, a well-controlled learning task in animals and humans, to elucidate these changes. Our studies have focused on the hippocampus, a temporal lobe structure known to be important for storage of new information during learning in mammalian brain.

Usefulness of determination of CA-125 in monitoring patients with ovarian carcinoma.

CA-125 was determined in 298 patients with ovarian carcinoma both initially, and during and after treatment. The upper limit of normal for CA-125 in our laboratory is 65 units/ml. Postoperatively, serum CA-125 antigen showed three distinct patterns: 20% of patients in whom levels fluctuate within the normal range have active disease; 100% of patients with fluctuations above 65 U/ml are found to have active disease; 100% of patients in whom levels of CA-125 increase progressively from any nadir, have active disease.

Influence of Tołpa Peat Preparation on the phagocytic activity and bactericidal properties of granulocytes in healthy volunteers.

It was found, that Tołpa Peat Preparation (TPP) administered to healthy volunteers in doses of 100-300 mg/day during 14 days evoked the stimulation of the phagocytic and bactericidal activity of the granulocytes. The dose of 600 mg/day causes only a transient and insignificant increase of phagocytic and bactericidal properties of the granulocytes.

Thrombospondin-induced adhesion of human platelets.

Washed human unactivated platelets attached and spread on thrombospondin (TSP)-coated microtiter plates. Platelet adhesion was promoted by divalent cations Mn2+, Mg2+, and Ca2+ as compared to buffer having all divalent cations complexed with EDTA. TSP-dependent adhesion was inhibited by anti-TSP fab fragments, an anti-TSP monoclonal antibody, an RGD-containing peptide, complex-specific anti-glycoprotein (GP)IIb-IIIa monoclonal antibodies (A2A9 or AP-2) and anti-VLA-2 monoclonal antibodies (6F1 and Gi9), but not by rabbit preimmune fab fragments, mouse IgG, an anti-GPIIIa monoclonal antibody, or monoclonal antibodies against either the human vitronectin receptor, glycocalicin, or GPIV.

[The effect of tienamycin on selected cellular immunologic parameters in mice during the course of viral-bacterial infections of the respiratory system].

The effect of tienamycin on selected parameters of the immunological system in mice infected with the influenza virus and Staphylococcus aureus was studied. Tienamycin was administered 24 hours, 2 hours prior the infection and 2 hours after the infection (model I), 24 hours and 48 hours after infecting the mice (model II). The authors analysed phagocytosis, bactericidal activity of peritoneal exudate cells and the LIF release induced by the staphylococcus antigen and the viral antigen by the spleen mice leukocytes.

Plasma lipoproteins mediate platelet adhesion.

Platelet adhesion to VLDL, LDL, HDL, and to a mixture of purified apolipoproteins was examined. Platelets adhered to all the classes of lipoproteins tested. VLDL and the apolipoprotein mixture promoted the greatest degree of adhesion.

Impaired cytoplasmic ionized calcium mobilization in inherited platelet secretion defects.

Defects in platelet cytoplasmic Ca++ mobilization have been postulated but not well demonstrated in patients with inherited platelet secretion defects. We describe studies in a 42-year-old white woman, referred for evaluation of easy bruising, and her 23-year-old son. In both subjects, aggregation and 14C-serotonin secretion responses in platelet-rich plasma (PRP) to adenosine diphosphate (ADP), epinephrine, platelet activating factor (PAF), arachidonic acid (AA), U46619, and ionophore A23187 were markedly impaired.

Changes in rat lung collagen after life-time treatment with vanadium.

Male Wistar rats were treated in the period from conception up to the 105th day of age with 40 and 60 ppm of vanadium, given as sodium metavanadate in the drinking water. It was found that total collagen and soluble collagen within the lungs of treated animals were significantly lower than in non-treated controls. The decrease in total collagen content observed was not dependent on the dose of vanadium administered.

[Effect of cefoperazone on the activity of selected parameters of cellular immunity in mice with experimental viral-bacterial infection].

We applied mixed, viral-bacterial infections of mice (with influenza virus to the respiratory tract and Staphylococcus aureus) intereperitoneally. We used Sodium Cefoperazone subcutaneously in the dose of 30 mg/kg body weight 24, 48 and 72 hours after the infection. We evaluated phagocytic activity of the granulocytes isolated from animals and bactericidal activity of these cells expressed as their chemiluminescent activity.

Pretreatment concentrations of breast carcinoma antigen (CA 15.3) and mucin-like carcinoma-associated antigen in patients with carcinoma of the breast.

Pretreatment serum concentrations of breast carcinoma antigen (CA 15.3) and mucin-like carcinoma-associated antigen (MCA) were determined in 129 patients with breast carcinoma. Concentrations of both markers were within the normal range in patients with Stage I disease.