Megakaryocytic cells synthesize and platelets secrete α5-laminins, and the endothelial laminin isoform laminin 10 (α5β1γ1) strongly promotes adhesion but not activation of platelets

2006 ◽  
Vol 95 (01) ◽  
pp. 85-93 ◽  
Author(s):  
Ayele Nigatu ◽  
Wondossen Sime ◽  
Gezahegn Gorfu ◽  
Tarekegn Geberhiwot ◽  
Ingegerd Andurén ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Blood Cells ◽  
Blood Platelets ◽  
Apparent Molecular Weight ◽  
Cell Aggregation ◽  
Adhesive Properties ◽  
Circulating Cells ◽  
Activated Platelets ◽  
Intracellular Expression

SummaryFollowing vascular injury, basement membrane (BM) components of the blood vessels are exposed to circulating cells and may contribute to hemostasis and/or thrombosis. Laminins 8 (LN-8) (α4β1γ1) and 10 (LN-10) (α5β1γ1) are major laminin isoforms of the endothelial BM, and LN-8 is also secreted by activated platelets. In the present study, we demonstrate synthesis of α5-laminins LN-10 and LN-11 (α5β2γ1) by megakaryocytic cells, and intracellular expression of these laminin isoforms in blood platelets. In contrast to platelet LNα4 chain that had an apparent molecular weight of 180 kDa and associated mostly to LNβ1 chain, platelet LNα5 consisted of 300/350 kDa polypeptides and associated mainly to LNβ2. Both α4– and α5-laminins were secreted by platelets following stimulation. When compared to recombinant human (rh) LN-8, rhLN-10 was much more adhesive to platelets, though adhesion to both proteins was largely mediated via α6β1 integrin. In spite of their adhesive properties, rhLN-8 and rhLN-10 induced neither P-selectin expression nor cell aggregation, two signs of platelet activation. This study demonstrates synthesis/expression of heterotrimeric α5-laminins in hematopoietic/blood cells, and provides evidence for the adhesive, but not activating, role of endothelial laminin isoforms in platelet biology.

Detection of inducible nitric oxide synthase inSchistosoma japonicumandS. mansoni

2004 ◽  
Vol 78 (1) ◽  
pp. 47-50 ◽  
Author(s):  
X.-C. Long ◽  
M. Bahgat ◽  
K. Chlichlia ◽  
A. Ruppel ◽  
Y.-L. Li
Keyword(s):  
Nitric Oxide ◽  
Molecular Weight ◽  
Inducible Nitric Oxide Synthase ◽  
Mouse Liver ◽  
Apparent Molecular Weight ◽  
Western Blots ◽  
Oxide Synthase ◽  
Host Tissues ◽  
Inducible Nitric Oxide

AbstractSchistosoma japonicumandS. mansoniwere tested for reactivity with an anti-inducible nitric oxide (iNOS) antibody and the distribution of iNOS was studied by immunofluorescent tests in different stages of the parasites. Reactivity was associated with the tegument in both larval schistosomes (sporocysts and cercariae) and eggs. With adult worms, the majority of the immunofluorescence was predominantly subtegumental inS. japonicumand parenchymal inS. mansoni. Fluorescence was also observed in host tissues (snails and mouse liver). In Western blots, the enzyme ofS. japonicumhad an apparent molecular weight of about 210 kDa. The possible role of worm and host iNOS in the parasite–host interrelation remains to be clarified.

THE SIGNIFICANCE OF THE CONTENT OF LOW AND MEDIUM MOLECULAR WEIGHT SUBSTANCES AND OLIGOPEPTIDES IN THE PATHOGENESIS OF VARICELLA

2021 ◽  
pp. 185-192
Author(s):  
Margity M.M. ◽  
Marzhokhova M.Y. ◽  
Hadzegova S.B.
Keyword(s):  
Molecular Weight ◽  
Infectious Diseases ◽  
Blood Plasma ◽  
Blood Cells ◽  
Maximum Level ◽  
Body Fluids ◽  
Endogenous Intoxication ◽  
Complicated Course

Endogenous intoxication syndrome is an important link in the pathogenesis of many infectious diseases. The role of low and medium molecular weight substances and oligopeptides acting as indicators of endogenous intoxication syndrome in the pathogenesis of varicella was studied, depending on the period of the disease, the severity of the course and the presence of complications. Based on this goal, 125 patients with varicella aged 18 to 49 years were examined. Determination of the content of substances of low and medium molecular weight in biological body fluids (blood plasma, red blood cells and urine) was carried out by the method of M. Ya.Malakhova (1995) on a spectrophotometer SF-46. The Lowru (1951) method was used to determine the level of oligopeptides in body fluids. The maximum level of substances of low and medium molecular weight was observed in patients with a complicated course of varicella during the height of the disease, as well as in patients with a severe course of the disease during the height. When determining the oligopeptides, the highest values were also obtained at the height of the disease in the severe course, as well as in the complicated course at admission. During the examination, the dependence of the studied indicators on the period of the disease, the severity, as well as the presence of complications was revealed. Thus, the most pronounced changes in the level of low and medium molecular weight substances and oligopeptides were observed in severe, and the least – in the mild course of varicella in all the studied media. In patients with developed complications, the disease was more severe, while the changes in the studied parameters were more pronounced.

Factors Influencing Thrombin Digestion Of Human Platelet Thrombospondin

1981 ◽  
Author(s):  
J W Lawler ◽  
F C Chao ◽  
J Palek
Keyword(s):  
Molecular Weight ◽  
Disulfide Bonds ◽  
Human Platelet ◽  
Blood Platelets ◽  
Polyacrylamide Gel Electrophoresis ◽  
Apparent Molecular Weight ◽  
Platelet Protein ◽  
Flow Through ◽  
Proteolytic Cleavages ◽  
Human Blood Platelets

Exposure of human blood platelets to thrombin results in the rapid release of a 420,000 dalton glycoprotein, designated thrombospondin, which is comprised of three polypeptides of equivalent molecular weight which are cross- linked by disulfide bonds. When purified human platelet thrombospondin is exposed to thrombin (4 units/ml) or plasmin (2 units/ml) for prolonged periods of time, proteolytic cleavages occur which result in the removal of 10,000 dalton and 30,000 dalton polypeptides with a concomitant decrease in the apparent molecular weight of the thrombospondin chains (Lawler, J.W. and Slayter, H.S., submitted for publication). In contrast, when the supernatant from thrombin- treated platelets is exposed to additional thrombin (4 units/ml) the 30,000 dalton, but not the 10,000 dalton fragment is released from thrombospondin. Proteolytic release of the 10,000 dalton polypeptide was inhibited by calcium and a nondialyzable component of the supernatant preparations. To further characterize the nondialyzable component, the supernatant was subjected to heparin-Sepharose affinity chromatography. Stepwise elution with varying NaCl concentrations yields a non-affinity flow through peak, a low affinity peak (eluted with 0.45 M NaCl) and a high affinity peak (eluted with 2.0 M NaCl). In addition to thrombospondin, the low affinity peak contains a β-thromboglobulin like protein as judged by RIA, apparent molecular weight on SDS-polyacrylamide gel electrophoresis (7,500-9,000 dalton) and heparin affinity. After dialysis of the low affinity peak against 0.14 M NaCl, 15 mM Tris-HCl (pH 7.6), 2 mM CaCl2 containing 0.02% NaN3, thrombin treatment resulted in the proteolytic release of the 30,000 dalton polypeptide, but not the 10,000 dalton polypeptide, from thrombospondin. These results suggest that calcium and a low molecular weight platelet protein can affect the pattern of thrombin digestion of thrombospondin.

scholarly journals Interactions of platelets with circulating tumor cells contribute to cancer metastasis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sina Anvari ◽  
Ernest Osei ◽  
Nima Maftoon
Keyword(s):  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Blood Cells ◽  
Cancer Metastasis ◽  
Computational Modelling ◽  
Main Function ◽  
Activated Platelets ◽  
Underlying Mechanisms ◽  
Metastatic Spreading

AbstractRecent studies have suggested that platelets have a crucial role in enhancing the survival of circulating tumor cells in the bloodstream and aggravating cancer metastasis. The main function of platelets is to bind to the sites of the damaged vessels to stop bleeding. However, in cancer patients, activated platelets adhere to circulating tumor cells and exacerbate metastatic spreading. Several hypotheses have been proposed about the platelet–cancer cell interactions, but the underlying mechanisms of these interactions are not completely understood yet. In this work, we quantitatively investigated the interactions between circulating tumor cells, red blood cells, platelets, plasma flow and microvessel walls via computational modelling at the cellular scale. Our highly detailed computational model allowed us to understand and quantitatively explain the role of platelets in deformation, adhesion and survival of tumor cells in their active arrest to the endothelium.

scholarly journals Identification of a specific glycoprotein ligand for P-selectin (CD62) on myeloid cells.

1992 ◽  
Vol 118 (2) ◽  
pp. 445-456 ◽  
Author(s):  
K L Moore ◽  
N L Stults ◽  
S Diaz ◽  
D F Smith ◽  
R D Cummings ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Myeloid Cells ◽  
Apparent Molecular Weight ◽  
Protein S ◽  
Similar Molecular Weight ◽  
Cell Extracts ◽  
Activated Platelets ◽  
Selectin Ligands ◽  
Reducing Conditions ◽  
Selectin Binding

P-selectin (CD62, GMP-140, PADGEM), a Ca(2+)-dependent lectin on activated platelets and endothelium, functions as a receptor for myeloid cells by interacting with sialylated, fucosylated lactosaminoglycans. P-selectin binds to a limited number of protease-sensitive sites on myeloid cells, but the protein(s) that carry the glycans recognized by P-selectin are unknown. Blotting of neutrophil or HL-60 cell membrane extracts with [125I]P-selectin and affinity chromatography of [3H]glucosamine-labeled HL-60 cell extracts were used to identify P-selectin ligands. A major ligand was identified with an approximately 250,000 M(r) under nonreducing conditions and approximately 120,000 under reducing conditions. Binding of P-selectin to the ligand was Ca2+ dependent and was blocked by mAbs to P-selectin. Brief sialidase digestion of the ligand increased its apparent molecular weight; however, prolonged digestion abolished binding of P-selectin. Peptide:N-glycosidase F treatment reduced the apparent molecular weight of the ligand by approximately 3,000 but did not affect P-selectin binding. Western blot and immunodepletion experiments indicated that the ligand was not lamp-1, lamp-2, or L-selectin, which carry sialyl Le(x), nor was it leukosialin, a heavily sialylated glycoprotein of similar molecular weight. The preferential interaction of the ligand with P-selectin suggests that it may play a role in adhesion of myeloid cells to activated platelets and endothelial cells.

Phase Microscope Studies of Living Blood-cells of the Tunicates under Normal and Experimental Conditions, with a Description of a New Type of Motile Cell Appendage

1961 ◽  
Vol s3-102 (57) ◽  
pp. 89-105
Author(s):  
WARREN ANDREW
Keyword(s):  
Blood Cells ◽  
Blood Platelets ◽  
Adhesive Properties ◽  
Experimental Conditions ◽  
Signet Ring ◽  
New Type ◽  
Ecteinascidia Turbinata ◽  
Bladder Cells ◽  
Fixed Cell ◽  
Morula Cell

The living blood-cells of tunicates have been studied by means of phase contrast microscopy. The species used were Ascidia atra Lesueur, Ecteinascidia turbinata, and Clavelina picta, all of which are common in the Bermuda region. Blood-cells in blood taken directly from the heart, or from the vessels, or elsewhere, particularly in the tunic of Ecteinascidia turbinata and Clavelina picta, were observed for periods ranging up to 24 h. A new type of appendage is described for those cells which we have called vacuolate cells (‘Q cells’ of Fulton, ‘signet-ring’ and ‘colorless morula cell’ of George). Individual cells show from 1 to 5 appendages, which are beaded and actively undulate. Fragments from the appendages continue to undulate. Such fragments bear some resemblance to blood-platelets of higher vertebrates in their strongly adhesive properties. In view of the morphological features, motility characteristics, and apparent functions, the terms lymphocyte and macrophage are considered appropriate for the finely granular and coarsely granular amoebocytes. No active swimming motions of the orange cells, nor of any other corpuscles were seen; but all of the types of cells, coloured and colourless, with the exception of the vacuolate cells, exhibit amoeboid progression. No transformation of vacuolate into green cells was brought about in our experiments with varying strengths of acid, contrary to the earlier findings of Fulton. Many types of blood-cells in the tunicates have ‘fixed cell’ counterparts in the tissues. It is suggested that the large ‘bladder cells’ of the tunic of A. atra Lesueur may be such counterparts of the vacuolate cells of the blood.

Modulation of endothelial inflammation after Methylene Blue: role of circulating cells

2014 ◽  
Vol 62 (S 01) ◽  
Author(s):  
I. Kanzler ◽  
F. Guo ◽  
N. Bogert ◽  
A. Moritz ◽  
A. Beiras-Fernandez
Keyword(s):  
Methylene Blue ◽  
Circulating Cells ◽  
Endothelial Inflammation

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

The Activation of Human Factor IX

1975 ◽  
Vol 33 (03) ◽  
pp. 553-563 ◽  
Author(s):  
B Østerud ◽  
K Laake ◽  
H Prydz
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl ◽  
Apparent Molecular Weight ◽  
Factor Ix ◽  
Factor Vii ◽  
Activate Factor ◽  
Human Factor Ix ◽  
Factor Xia ◽  
Tissue Thromboplastin ◽  
Native Factor

SummaryThe activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IX a had an apparent molecular weight of about 42–45000 in sodium dodecyl sul-phate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions whereas Ca2+-ions did not influence the activation by kallikrein. A mixture of tissue thromboplastin and factor VII or RusselPs-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

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