Search results for "Adenosine diphosphate"
showing 10 items of 63 documents
A comparative biochemical, pharmacological and immunological study of Clostridium novyi alpha-toxin, C. difficile toxin B and C. sordellii lethal tox…
1991
The three clostridial cytotoxins, i.e. alpha-toxin of C. novyi (Tox alpha-nov), toxin B of C. difficile (ToxB-dif) and lethal toxin of C. sordellii (LT-sor) consist of single peptide chains of about 200,000 (Tox alpha-nov), 250,000 (LT-sor) and 275,000 (ToxB-dif) mol. wts. ToxB-dif and LT-sor but not Tox alpha-nov cross-reacted with rabbit polyclonal antibodies. Toxicity upon i.v. injection in mice was similar (LD50, 100 hr, 50-200 ng/kg) and was characterized by a slowly developing fluid loss into the interstitial space. When injected into the rat paw the toxins caused a delayed local edema lasting for days. In vitro the three toxins provoked a persistent retraction of endothelial cells cu…
In-vitro and Ex-vivo Inhibition of Blood Platelet Aggregation by Naftazone
1996
Abstract Because of the considerable interest in the role of platelets and antiplatelet therapy in cardiovascular disease, including the aggregation of platelets to each other during arterial thrombosis and atherogenesis, we have studied the effect of naftazone (Etioven), an original vasculotropic drug on platelet aggregation. Rat and human platelets were prepared and incubated in-vitro with different concentrations of naftazone. We found that naftazone inhibited both platelet secretion and aggregation in platelet-rich plasma (PRP) and washed platelets after stimulation with thrombin or ADP. Rats were also treated intraperitoneally for five days with various naftazone doses (0.125-10 mg kg−…
Deciphering of ADP-induced, phosphotyrosine-dependent signaling networks in human platelets by Src-homology 2 region (SH2)-profiling.
2012
Tyrosine phosphorylation plays a central role in signal transduction controlling many important biological processes. In platelets, the activity of several signaling proteins is controlled by tyrosine phosphorylation ensuring proper platelet activation and aggregation essential for regulation of the delicate balance between bleeding and hemostasis. Here, we applied Src-homology 2 region (SH2)-profiling for deciphering of the phosphotyrosine state of human platelets activated by adenosine diphosphate (ADP). Applying a panel of 31 SH2-domains, rapid and complex regulation of the phosphotyrosine state of platelets was observed after ADP stimulation. Specific inhibition of platelet P2Y receptor…
Reciprocal regulation of human platelet function by endogenous prostanoids and through multiple prostanoid receptors
2014
Platelets are permanently exposed to a variety of prostanoids formed by blood cells or the vessel wall. The two major prostanoids, prostacyclin and thromboxane act through well established pathways mediated by their respective G-protein coupled receptors inhibiting or promoting platelet aggregation accordingly. Yet the role of other prostanoids and prostanoid receptors for platelet function regulation has not been thoroughly investigated. We aimed at a comprehensive analysis of prostanoid effects on platelets, the receptors and pathways involved and functional consequences. We analyzed cAMP formation and phosphorylation of proteins pivotal to platelet function as well as functional platelet…
The effect of hormone replacement therapy on Ca2+ mobilization and P-selectin (CD62P) expression in platelets examined under flow cytometry.
2004
A series of events, such as increase of cytoplasmic free calcium (Ca 2+ ) and expression of P-selectin (CD62P), an adhesion molecule, on the platelet surface, are significant indicators of platelet activation. We have used flow cytometry to examine Ca 2+ mobilization and CD62P expression in platelets in whole blood obtained in women prior to, and after, different forms of hormone replacement therapy. Thirty-two women completed a protocol consisting of two consecutive 1-month periods under oestradlol (E 2 ), administered orally (2 mg/day) or transdermally (50 μg/day) in random order, followed by a 4-week transdermal sequential regime, in which, during the last 14 days, either progesterone (3…
Differentiative pathway activated by 3-aminobenzamide, an inhibitor of PARP, in human osteosarcoma MG-63 cells
2004
AbstractThis study describes the molecular mechanism by which treatment with 3-AB, a potent inhibitor of PARP, allows human osteosarcoma MG-63 cells to restrict growth and enter differentiation. Our findings show that in MG-63 cells, aberrant gene expression keeps Rb protein constitutively inactivated through hyperphosphorylation and this promotes uncontrolled proliferation of the cells. After 3-AB-treatment, the poly(ADP-ribosyl)ation of nuclear proteins markedly decreases and this results in an increase in both the hypophosphorylated active form of Rb and pRb/E2F complexes. These effects are accompanied by G1 arrest, downregulation of gene products required for proliferation (cyclin D1, β…
Changes in the proton potential and the cellular energetics of Escherichia coli during growth by aerobic and anaerobic respiration or by fermentation.
1998
The energetic parameters of Escherichia coli were analyzed for the aerobic/anaerobic transition. The electrochemical proton potential (delta p) across the cytoplasmic membrane was determined in the steady state of respiration with O2, nitrate, fumarate, dimethylsulfoxide (Me2SO), and for fermentation. With O2, a proton potential of -160 mV was obtained. For anaerobic respiration with nitrate, fumarate or Me2SO, delta p decreased only slightly by about 20 mV in contrast to earlier assumptions, whereas delta p dropped by approximately 40 mV during fermentation. Under all conditions, the membrane potential (delta psi) contributed the major portion to delta p. The cellular ATP levels were highe…
Flow cytometric kinetic assay of calcium mobilization in whole blood platelets using Fluo-3 and CD41
1999
Background: Platelet activation plays a major role in the physiology and pathology of hemostasis. Flow cytometry is a promising approach for the structural and functional analysis of platelets. However, the choice of adequate biological parameters and most technical issues are still under discussion. A rise in cytosolic free Ca 21 is a key early event that follows platelet stimulation and precedes several activation responses, including shape change, aggregation, secretion, and expression of procoagulant activity. Our objective was to set up a fast and sensitive flow cytometric method to determine the kinetics of intracellular Ca 21 mobilization in platelets, which could be performed with t…
The adenine nucleotide content of rat liver during infusions of carbohydrates and polyols
1972
Injection of large doses of fructose, sorbitol, or a mixture of glucose, fructose and xylitol in rats causes a drop of liver ATP, total adenine nucleotides and Pi and a rise of AMP, which is in agreement with data from the literature. These changes are considered as a transient disturbance of homeostasis by compounds which are rapidly phosporylated in the liver. This is confirmed by the fact that during continuous infusion of these and other compounds at doses of 1,5 g · kg−1 · h−1 there was no such change. It is concluded that infusions of fructose or of the other carbohydrates tested with rates not exceeding those recommended for parenteral nutrition (0,5 g · kg−1 · h−1) are not likely to…
Inhibition of gluconeogenesis by extracellular ATP in isolated rat hepatocytes.
1991
The aim of this study was to determine the effect of externally added ATP on gluconeogenesis by isolated hepatocytes from starved rats. High concentrations of extracellular ATP inhibited gluconeogenesis from lactate and pyruvate but not from glycerol or fructose. This inhibition was associated with an increase in intracellular adenosine contents. ADP, AMP, or adenosine but not guanosine 5'triphosphate, inosine 5' triphosphate, or adenine also inhibited gluconeogenesis. alpha, beta-Methylene-ATP, a nonmetabolizable structural analogue of ATP, did not affect the rate of gluconeogenesis. Intracellular ATP levels were increased by externally added ATP or adenosine, but ATP-to-ADP ratios in the…