Concanavalin A-induced Aggregation of Human Blood Platelets

1975 ◽  
Vol 33 (02) ◽  
pp. 354-360 ◽  
Author(s):  
Heinrich Patscheke ◽  
Reinhard Brossmer
Keyword(s):  
Concanavalin A ◽  
Binding Capacity ◽  
Specific Binding ◽  
Blood Platelets ◽  
Residual Effect ◽  
Independent Effect ◽  
Con A ◽  
Experimental Conditions ◽  
Main Effect ◽  
Induced Aggregation

SummaryConcanavalin A (CON A) causes platelets to aggregate. A Ca++-independent effect of CON A could be separated from a main effect which depends on Ca++. The main effect probably is a consequence of the CON A-induced platelet release reaction and therefore is platelet-specific. The weak residual effect observed in the presence of Na2EDTA may be due to a similar mechanism as has been demonstrated for CON A-induced aggregations of several other normal and malignant transformed animal cells.Na2EDTA did not inhibit the carbohydrate-specific binding capacity of CON A. Therefore, Na2EDTA appears not to demineralize the CON A molecules under these experimental conditions.α-methyl-D-glucoside inhibits the Ca++-independent as well as the Ca++-dependent effect of CON A.Pretreatment by neuraminidase stimulated the platelet aggregation induced by CON A. It is possible that removal of terminal sialic acid residues makes additional receptors accessible for the binding of CON A.

Autophagy Induction in T Cell-Independent Acute Hepatitis Induced by Concanavalin a in SCID/NOD Mice

2008 ◽  
Vol 21 (4) ◽  
pp. 817-826 ◽  
Author(s):  
C-P. Chang ◽  
H-Y. Lei
Keyword(s):  
T Cell ◽  
Acute Hepatitis ◽  
Concanavalin A ◽  
Specific Binding ◽  
Nod Mice ◽  
Con A ◽  
Interacting Protein ◽  
Autophagy Induction ◽  
Adenovirus E1b ◽  
Immunocompetent Mice

Concanavalin A (Con A) is known to induce acute hepatitis that is mediated by activation of NKT- and T-cell and cytokine production in immunocompetent mice. The observation of Con A-induced autophagic cell death of hepatoma cells via a Bcl-2/adenovirus E1B 19 kDa-interacting protein 3 mediated autophagic pathway made us re-evaluate the effect of Con A-induced hepatitis in mice. Con A was administrated intravenously to BABL/c, SCID, or SCID/NOD mice at doses of 20, 30 or 40 mg/kg, respectively, to induce acute hepatitis. The levels of hepatitis and autophagy induction were both analyzed. We found that Con A can induce acute hepatitis in SCID or SCID/NOD mice with a kinetics similar to that of BALB/c, but requiring a higher dose of Con A. No lymphocyte infiltrations were found in SCID or SCID/NOD mice, and the cytokine productions were different. An autophagy with microtubule-associated protein light chain 3-II conversion was demonstrated in the liver post-Con A injection in SCID/NOD mice. Due to the mannose/glucose-specific binding on cell membrane, Con A can induce a T-cell-independent acute hepatitis with autophagy in SCID/NOD mice.

Interaction of β2-Glycoprotein-I with Human Blood Platelets: Influence Upon the ADP-Induced Aggregation

1985 ◽  
Vol 54 (02) ◽  
pp. 397-401 ◽  
Author(s):  
Johannes Nimpf ◽  
Helmut Wurm ◽  
Gerhard M Kostner
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Blood Platelets ◽  
Gel Filtration ◽  
Human Platelets ◽  
Glycoprotein I ◽  
Unspecific Binding ◽  
Induced Aggregation ◽  
Human Blood Platelets

SummaryThe interaction of β2-glycoprotein-I (β2-G-I), a plasma constituent of unknown function, with blood platelets was studied. The following results were obtained: 1) β2-G-I binds to washed human platelets isolated by centrifugation (WP) at one kind of specific, saturable binding sites. The dissociation constant was found to be approx. 1 × 10−6M.2) In the presence of physiological concentrations of Ca++ (2.5 mM), this specific binding is markedly reduced. Unspecific binding of β2-G-I to platelets, however, is not influenced by Ca++.3) Platelets prepared by gel filtration (GFP), differing in their in vitro aggregability from WP, exhibit no specific binding of β2-G-I. Binding to GFP is also not induced by activation with thrombin, collagen or ADP.4) β2-G-I causes significant alteration of the ADP-induced aggregation of GFP. Aggregation induced by thrombin, collagen, arachidonic acid or PAF-acether, however is not altered by β2G-I.It is suggested, that pelleting during centrifugation causes irreversible rearrangements in the membrane of platelets.

scholarly journals Effects of Lectins on Blood Platelets from Various Species

1977 ◽  
Author(s):  
O. Tangen ◽  
B. Karlstam ◽  
S. Bygdeman
Keyword(s):  
Shape Change ◽  
Blood Platelets ◽  
Human Platelets ◽  
Serotonin Release ◽  
Variable Degree ◽  
Con A ◽  
Platelet Release ◽  
Induced Aggregation ◽  
Aggregation Of Platelets ◽  
Platelet Shape

Earlier it has been shown that different lectins induce a variable degree of aggregation of platelets. The present study confirmed previous data and demonstrated that wheat germ agglutinin (WGA) was very active, 1eucoagglutinin had about a tenth of the activity of WGA on a concentration basis, and Con A had a weak aggregating effect on human gel filtered platelets (GFP). Soy bean lectin did not aggregate human GFP.The fact that adenosine inhibited WGA- and leucoagglutinin-induced aggregation that WGA and Con A caused serotonin release, and that the aggregation- curves indicated platelet shape change are indications that the lectins influenced glycosyl moieties involving one or more molecules relevant to release and aggregation reaction.GFP were markedly more responsive to the lectins than platelets in plasma, probably due to interfering glycosyl groups amongst the plasma constituents.Platelets from man, rabbit, rat, cow and pig reacted differently towards the lectins, human platelets being the most reactive and bovine and porcine platelets being almost unreactive. These results pose intriguing questions regarding the glycosyl content of platelet membranes in different species and their relation to platelet release and aggregation.

Binding and uptake of concanavalin A into rat brain synaptosomes: evidence for synaptic vesicle recycling

1983 ◽  
Vol 219 (1217) ◽  
pp. 413-422 ◽  
Keyword(s):  
Plasma Membrane ◽  
Rat Brain ◽  
Synaptic Vesicle ◽  
Concanavalin A ◽  
Specific Binding ◽  
Synaptic Cleft ◽  
Con A ◽  
Coated Pits ◽  
Rat Brain Synaptosomes ◽  
Brain Synaptosomes

The specific binding of radioiodinated concanavalin A ( 125 I-con A) to rat brain synaptosomes was shown to be saturable. In the presence of ex­cess con A binding was rapid and was completed within 5 min ( t 1/2 was 25 s) at 37°C, and at saturation the amount bound did not change over time. Under the electron microscope, concanavalin A-ferritin (con A-ft) bound to synaptosomes in two regions: in the extra-junctional plasma membrane and within the synaptic cleft of Gray type 1 and 2 synapses. Synaptosomes incubated with con A-ft at 37°C internalized bound lectin by endocytosis through coated pits. Endocytosis took place in the extra-junctional membrane, because it can occur before con A-ft has penetrated into the synaptic cleft, and continued for a considerable time (more than 30 min) after saturation of the receptor(s). Synaptic vesicles, which have at least two con A receptors on the internal aspect of their membranes, and cisternae, become labelled. When exocytosis was induced in synaptosomes by K + depolarizations, synaptic vesicle con A receptors became incorporated into the plasma membrane and were labelled with 125 I-con A causing a 2.5-fold increase in con A binding that was Ca 2+ dependent. These experiments thus provide evidence for the transient incorporation of synaptic vesicle membrane glycoproteins into the plasma membrane during transmitter release.

scholarly journals Concanavalin A-reactive nuclear matrix glycoprotein

1997 ◽  
Vol 20 (4) ◽  
pp. 631-638 ◽  
Author(s):  
Benedicto de Campos Vidal ◽  
Silvya Stuchi Maria ◽  
Louis Bernard Klaczko
Keyword(s):  
Concanavalin A ◽  
Nuclear Matrix ◽  
High Performance ◽  
Binding Capacity ◽  
Chromatin Condensation ◽  
Polytene Chromosomes ◽  
Cell Types ◽  
Dry Mass ◽  
Interference Microscopy ◽  
Con A

The binding capacity of concanavalin A (Con A) to condensed euchromatin and heterochromatin was investigated in chicken erythrocyte nuclei (CEN), mouse liver cells, Zea mays mays meristematic cells and Drosophila melanogaster polytene chromosomes after 4 N HCl hydrolysis to determine whether binding was preferentially occurring in bands and heterochromatin. Dry mass (DM) variation was investigated in CEN by interference microscopy. Feulgen and Con A reactions were employed for all materials to correlate the loci of the two reactions. Quantifications and topological verifications were carried out by video image analysis (high performance cytometry). It was observed that 4 N HCl hydrolysis caused an important DM loss in CEN leaving a level corresponding to the average DNA DM content. In this material, Con A binding was restricted to the nuclear envelope, which reinforces the idea of the absence of a nuclear matrix in these cells. The other cell types exhibited a correspondence of Feulgen-positive and Con A-reactive areas. The Con A reaction was highly positive in the condensed chromatin areas and heterochromatin. This fact led us to speculate that Con A-positive proteins may play a role in the chromatin condensation mechanism, endowing this structure with physico-chemical stability towards acid hydrolysis and contributing to its rheological properties.

scholarly journals Isolation of concanavalin a caps during various stages of formation and their association with actin and myosin

1979 ◽  
Vol 80 (3) ◽  
pp. 751-758 ◽  
Author(s):  
J Condeelis
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Concanavalin A ◽  
Specific Binding ◽  
Lectin Binding ◽  
Metabolic Energy ◽  
Con A ◽  
Thin Filaments ◽  
Lectin Receptor ◽  
Receptor Complexes

Regions of plasma membrane of dictyostelium discoideum amoebae that contain concanavalin A (Con A)-receptor complexes are more resistant to disruption by Triton X-100. This resistance makes possible the isolation of Con A-associated membrane fragments in sufficient quantity and homogeneity to permit the direct biochemical and ultrastructural study of receptor-cytoskeletal interactions across the cell membrane. After specific binding of Con A to the cell surface, a large amount of the cell's actin and myosin copurifies with the plasma membrane fragments. Myosin is more loosely bound to the isolated membranes that actin and is efficiently removed by treating membranes with ATP and low ionic strength. If cells are not lysed immediately after lectin binding, all of the Con A that is bound to the cell surface is swept into a cap in a process requiring metabolic energy. When cells are lysed at different stages of cap formation, the amount of actin and myosin that copurifies with the isolated membranes remains the same. Thick and thin filaments that are attached to the protoplasmic surface of the isolated membranes underlie lectin-receptor complexes during all stages of cap formation. Once the cap is complete, the amount of actin and myosin that tightly bound to the plasma membrane is concentrated into the cap along with the Con A-receptor complexes. These results suggest that the ATP-dependent sliding of membrane-associated actin and myosin filaments is responsible for the accumulation of Con A-receptor complexes into a cap on the cell surface.

Ultrastructural Characteristics of Platelets Separated from Plasma by ADP-Induced Aggregation

1976 ◽  
Vol 34 ◽  
pp. 164-165
Author(s):  
B.A. Shinoda ◽  
M.D. Hardison ◽  
S.F. Mohammad ◽  
H.Y.K. Chuang ◽  
R.G. Mason
Keyword(s):  
Blood Platelets ◽  
Gel Filtration ◽  
Differential Centrifugation ◽  
Ultrastructural Characteristics ◽  
Induced Aggregation

The utilization of blood platelets in experimentation frequently requires their separation from blood and subsequent resuspension in media of known composition. Several methods are available for preparation of isolated platelets (1-3) by differential centrifugation or gel filtration, but most methods are tedious and time consuming. Often platelets obtained by use of such methods are in a state different functionally and ultrastructurally from that of platelets in plasma (4).Recently Mohammad, Reddick, and Mason (5) reported a method in which platelets were separated from plasma by ADP-induced aggregation, washed several times, and then incubated in a carefully selected medium that resulted in deaggregation of platelets.

Platelet Aggregation Caused by Dithiothreitol

1984 ◽  
Vol 51 (01) ◽  
pp. 119-124 ◽  
Author(s):  
M B Zucker ◽  
N C Masiello
Keyword(s):  
Shape Change ◽  
Blood Platelets ◽  
Dense Granule ◽  
Metabolic Inhibitors ◽  
Electrophoretic Patterns ◽  
Discernible Effect ◽  
Variable Extent ◽  
Triton X ◽  
Induced Aggregation ◽  
Platelet Shape

SummaryMacIntyre et al. showed that over 1 mM dithiothreitol (DTT) aggregates blood platelets in the presence of fibrinogen; aggregation is not inhibited by prostaglandin E1. We confirmed their data and found that 70 mM 2-mercaptoethanol was also active. DTT- induced aggregation was not associated with platelet shape change or secretion of dense granule contents, was not inhibited by tetracaine or metabolic inhibitors, was prevented at pH 6.5, and prevented, reversed, or arrested by EDTA, depending on when the EDTA was added. DTT did not cause aggregation of thrombasthenic, EDTA-treated, or cold (0° C) platelets, which also failed to aggregate with ADP. Platelets stimulated with DTT bound 125I-labeled fibrinogen. Thus DTT appears to “expose” the fibrinogen receptors. SDS gel electrophoresis of platelet fractions prepared by use of Triton X-114 showed that aggregating concentrations of DTT reduced proteins of apparent Mr 69,000 and 52,000 (probably platelet albumin) and, to a variable extent, glycoproteins Ib, IIb and III. Exposure of unlabeled or 125I- labeled platelets to ADP had no discernible effect on the electrophoretic patterns.

The Effect of Calcium and Magnesium on Rabbit Blood Platelet Aggregation in Vitro

1964 ◽  
Vol 12 (01) ◽  
pp. 179-200 ◽  
Author(s):  
Torstein Hovig
Keyword(s):  
Platelet Aggregation ◽  
Cation Exchange ◽  
Calcium Concentration ◽  
Blood Platelets ◽  
Blood Platelet ◽  
Rabbit Blood ◽  
Calcium And Magnesium ◽  
Induced Aggregation ◽  
Blood Platelet Aggregation

SummaryThe effect of calcium and magnesium on the aggregation of rabbit blood platelets in vitro was studied, with the following results:1. Platelet aggregation induced by ADP or collagen could be prevented by EGTA or EDTA. The aggregating effect was restored by recalcification. The effect was also restored by addition of magnesium in EDTA-PRP, but not in EGTA-PRP unless a surplus of calcium was present.2. Calcium remained in concentrations of the order of 0.15–0.25 mM after dialysis or cation exchange of plasma. Aggregation of washed platelets resuspended in such plasma could not be produced with ADP or collagen, unless the calcium concentration was increased or that magnesium was added.3. The adhesiveness of blood platelets to collagen was reduced in EGTA-PRP and EDTA-PRP. Release of ADP from platelets influenced by collagen could not be demonstrated either in EGTA-PRP (presence of magnesium) or in EDTA-PRP.4. It is concluded that calcium is a necessary factor both for the reaction leading to release of ADP and for the the aggregation produced by ADP.5. Thrombin induced aggregation of washed platelets suspended in tris-buffered saline in the presence of calcium. No effect of magnesium could be observed unless small quantities of calcium were present.

Deficiency of (33P)2MeS-ADP Binding Sites on Platelets with Secretion Defect, Normal Granule Stores and Normal Thromboxane A2 Production

1997 ◽  
Vol 77 (05) ◽  
pp. 0986-0990 ◽  
Author(s):  
Marco Cattaneo ◽  
Rossana Lombardi ◽  
Maddalena L Zighetti ◽  
Christian Gachet ◽  
Philippe Ohlmann ◽  
...  
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Thromboxane A2 ◽  
Normal Subjects ◽  
Congenital Defects ◽  
Normal Production ◽  
Adp Receptor ◽  
Partial Deficiency ◽  
Induced Aggregation ◽  
Platelet Secretion

SummaryBy the term “Primary Secretion Defect” (PSD), we mean a common heterogeneous group of congenital defects of platelet secretion, characterized by a normal primary wave of platelet aggregation induced by ADP and other agonists, a normal concentration of platelet granule contents, and normal production of thromboxane A2. The biochemical abnormalities responsible for PSD are not well known. Since a secretion defect similar to PSD is found in platelets that are severely deficient of binding sites for the ADP analogue 2MeS-ADP and do not aggregate in response to ADP, we tested the hypothesis that PSD platelets have moderately decreased 2MeS-ADP binding sites, which may be sufficient for normal ADP-induced aggregation but not for potentiating platelet secretion. The specific binding of [33P]2MeS-ADP to platelets from 3 PSD patients (347,443 and 490 sites/platelet; KD 2.8-3.9 nM) was lower than to platelets from 24 normal subjects (647 [530-1102]; KD = 3.8 [2.3-7.3]) (median [range]). Normal values were found in a fourth PSD patient (710; KD 3.7). The degree of inhibition of PGE1- induced cAMP increase by 0.1 |μM ADP was lower in patients than in controls. The secretion induced by the endoperoxide analogue U46619 from normal, acetylsalicylic acid-treated platelets under conditions that prevented the formation of large aggregates was potentiated by 1 fimol/1 ADP and inhibited by apyrase. These findings indicate that a partial deficiency of the platelet ADP receptor(s) might be responsible for the defect of platelet secretion in some PSD patients and that ADP potentiates platelet secretion independently of the formation of large aggregates and thromboxane A2 production.

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