Lipopolysaccharide biosynthesis-related genes are required for colony pigmentation of Porphyromonas gingivalis

The periodontopathic bacterium Porphyromonas gingivalis forms pigmented colonies when incubated on blood agar plates as a result of accumulation of μ-oxo haem dimer on the cell surface. Gingipain–adhesin complexes are responsible for production of μ-oxo haem dimer from haemoglobin. Non-pigmented mutants (Tn6-5, Tn7-1, Tn7-3 and Tn10-4) were isolated from P. gingivalis by Tn4351 transposon mutagenesis [Hoover & Yoshimura (1994), FEMS Microbiol Lett 124, 43–48]. In this study, we found that the Tn6-5, Tn7-1 and Tn7-3 mutants carried Tn4351 DNA in a gene homologous to the ugdA gene encoding UDP-glucose 6-dehydrogenase, a gene encoding a putative group 1 family glycosyltransferase and a gene homologous to the rfa gene encoding ADP heptose-LPS heptosyltransferase, respectively. The Tn10-4 mutant carried Tn4351 DNA at the same position as that for Tn7-1. Gingipain activities associated with cells of the Tn7-3 mutant (rfa) were very weak, whereas gingipain activities were detected in the culture supernatants. Immunoblot and mass spectrometry analyses also revealed that gingipains, including their precursor forms, were present in the culture supernatants. A lipopolysaccharide (LPS) fraction of the rfa deletion mutant did not show the ladder pattern that was usually seen for the LPS of the wild-type P. gingivalis. A recombinant chimera gingipain was able to bind to an LPS fraction of the wild-type P. gingivalis in a dose-dependent manner. These results suggest that the rfa gene product is associated with biosynthesis of LPS and/or cell-surface polysaccharides that can function as an anchorage for gingipain–adhesin complexes.

Download Full-text

New Insights on NETosis Induced by Entamoeba histolytica: Dependence on ROS from Amoebas and Extracellular MPO Activity

Antioxidants ◽

10.3390/antiox10060974 ◽

2021 ◽

Vol 10 (6) ◽

pp. 974

Author(s):

César Díaz-Godínez ◽

Joshue Fabián Jorge-Rosas ◽

Mario Néquiz ◽

Santiago Martínez-Calvillo ◽

Juan P. Laclette ◽

...

Keyword(s):

Cell Surface ◽

Nadph Oxidase ◽

Entamoeba Histolytica ◽

Pathogen Detection ◽

Dependent Manner ◽

Antimicrobial Proteins ◽

Nadph Oxidase Activity ◽

Mitochondrial Ros ◽

Pre Treatment ◽

Dose Dependent

NETosis is a neutrophil process involving sequential steps from pathogen detection to the release of DNA harboring antimicrobial proteins, including the central generation of NADPH oxidase dependent or independent ROS. Previously, we reported that NETosis triggered by Entamoeba histolytica trophozoites is independent of NADPH oxidase activity in neutrophils, but dependent on the viability of the parasites and no ROS source was identified. Here, we explored the possibility that E. histolytica trophozoites serve as the ROS source for NETosis. NET quantitation was performed using SYTOX® Green assay in the presence of selective inhibitors and scavengers. We observed that respiratory burst in neutrophils was inhibited by trophozoites in a dose dependent manner. Mitochondrial ROS was not also necessary, as the mitochondrial scavenger mitoTEMPO did not affect the process. Surprisingly, ROS-deficient amoebas obtained by pre-treatment with pyrocatechol were less likely to induce NETs. Additionally, we detected the presence of MPO on the cell surface of trophozoites after the interaction with neutrophils and found that luminol and isoluminol, intracellular and extracellular scavengers for MPO derived ROS reduced the amount of NET triggered by amoebas. These data suggest that ROS generated by trophozoites and processed by the extracellular MPO during the contact with neutrophils are required for E. histolytica induced NETosis.

Download Full-text

Dectin-1-Mediated Production of Pro-Inflammatory Cytokines Induced by Yeast β-Glucans in Bovine Monocytes

Frontiers in Immunology ◽

10.3389/fimmu.2021.689879 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ana R. V. Pedro ◽

Tânia Lima ◽

Ricardo Fróis-Martins ◽

Bárbara Leal ◽

Isabel C. Ramos ◽

...

Keyword(s):

Gene Expression ◽

Cell Surface ◽

Inflammatory Cytokines ◽

Surface Expression ◽

Cell Surface Receptor ◽

Dependent Manner ◽

Feed Supplements ◽

Surface Receptor ◽

Dose Dependent ◽

Pro Inflammatory Cytokines

Yeast-derived products containing β-glucans have long been used as feed supplements in domesticated animals in an attempt to increase immunity. β-glucans are mainly recognized by the cell surface receptor CLEC7A, also designated Dectin-1. Although the immune mechanisms elicited through Dectin-1 activation have been studied in detail in mice and humans, they are poorly understood in other species. Here, we evaluated the response of bovine monocytes to soluble and particulate purified β-glucans, and also to Zymosan. Our results show that particulate, but not soluble β-glucans, can upregulate the surface expression of costimulatory molecules CD80 and CD86 on bovine monocytes. In addition, stimulated cells increased production of IL-8 and of TNF, IL1B, and IL6 mRNA expression, in a dose-dependent manner, which correlated positively with CLEC7A gene expression. Production of IL-8 and TNF expression decreased significantly after CLEC7A knockdown using two different pairs of siRNAs. Overall, we demonstrated here that bovine monocytes respond to particulate β-glucans, through Dectin-1, by increasing the expression of pro-inflammatory cytokines. Our data support further studies in cattle on the induction of trained immunity using dietary β-glucans.

Download Full-text

Autocrine stimulation of interleukin 1 beta in acute myelogenous leukemia cells.

Journal of Experimental Medicine ◽

10.1084/jem.166.5.1597 ◽

1987 ◽

Vol 166 (5) ◽

pp. 1597-1602 ◽

Cited By ~ 48

Author(s):

K Sakai ◽

T Hattori ◽

M Matsuoka ◽

N Asou ◽

S Yamamoto ◽

...

Keyword(s):

Acute Myelogenous Leukemia ◽

Interleukin 1 ◽

Myelogenous Leukemia ◽

Leukemic Cells ◽

Dependent Manner ◽

Acute Myelogenous ◽

Autocrine Stimulation ◽

Basal Proliferation ◽

Culture Supernatants ◽

Dose Dependent

A significant increase in CD25 antigen-positive cells by IL-1 was observed in cells of a patient with M7 acute myelogenous leukemia. Basal proliferation and expression of CD25 antigen by the M7 leukemic cells were inhibited by addition of anti-IL-1 beta antibody in a dose-dependent manner, but not by rabbit anti-IL-1 alpha antibody. Culture supernatants of these leukemic cells contained IL-1 activity, which was specifically inhibited by addition of anti-IL-1 beta antibody, and Northern blot analysis detected intracellular IL-1 beta mRNA. These results indicated that autocrine secretion of IL-1 beta was involved in proliferation of some myelogenous leukemic cells.

Download Full-text

Missense mutations in the gene encoding prothrombin corresponding to Arg596 cause antithrombin resistance and thrombomodulin resistance

Thrombosis and Haemostasis ◽

10.1160/th16-03-0223 ◽

2016 ◽

Vol 116 (12) ◽

pp. 1022-1031 ◽

Cited By ~ 8

Author(s):

Yuki Takagi ◽

Moe Murata ◽

Toshihiro Kozuka ◽

Yukiko Nakata ◽

Ryo Hasebe ◽

...

Keyword(s):

Surface Plasmon Resonance ◽

Residual Activity ◽

Base Substitution ◽

Enzyme Linked Immunosorbent Assay ◽

Dependent Manner ◽

Missense Mutations ◽

Wild Type ◽

Gene Encoding ◽

Single Base

SummaryAntithrombin (AT) and thrombomodulin (TM) play important roles in the process of natural anticoagulation in vivo. Recently, we reported that the prothrombin Yukuhashi mutation (p.Arg596Leu) was associated with AT and TM resistance-related thrombophilia. To assess the AT and TM resistances associated with other missense mutations by single base substitution in the Arg596 codon, we generated recombinant variants (596Gln, 596Trp, 596Gly, and 596Pro) and investigated the effects on AT and TM anticoagulant functions. All variants except 596Pro were secreted in amounts comparable to that of the wild-type but exhibited variable procoagulant activities. After a 30-minute inactivation by AT, the relative residual activity of wild-type thrombin decreased to 15 ± 4.0%, in contrast to values of all variants were maintained at above 80%. The thrombin–AT complex formation, as determined by enzyme-linked immunosorbent assay, was reduced with all tested variants in the presence and absence of heparin. In the presence of soluble TM (sTM), the relative fibrinogen clotting activity of wild-type thrombin decreased to 16 ± 0.12%, whereas that of tested variants was 37%–56%. In a surface plasmon resonance assay, missense Arg596 mutations reduced thrombin–TM affinity to an extent similar to the reduction of fibrinogen clotting inhibition. In the presence of sTM or cultured endothelial-like cells, APC generation was enhanced differently by variant thrombins in a thrombin–TM affinity- dependent manner. These data indicate that prothrombin Arg596 missense mutations lead to AT and TM resistance in the variant thrombins and suggest that prothrombin Arg596 is important for AT- and TM- mediated anticoagulation.

Download Full-text

CbfA, the C-Module DNA-Binding Factor, Plays an Essential Role in the Initiation of Dictyostelium discoideum Development

Eukaryotic Cell ◽

10.1128/ec.3.5.1349-1358.2004 ◽

2004 ◽

Vol 3 (5) ◽

pp. 1349-1358 ◽

Cited By ~ 11

Author(s):

Thomas Winckler ◽

Negin Iranfar ◽

Peter Beck ◽

Ingo Jennes ◽

Oliver Siol ◽

...

Keyword(s):

Dna Binding ◽

Cell Density ◽

Dictyostelium Discoideum ◽

Ectopic Expression ◽

Development Program ◽

Cell Physiology ◽

Dependent Manner ◽

Wild Type ◽

Gene Encoding ◽

Multicellular Development

ABSTRACT We recently isolated from Dictyostelium discoideum cells a DNA-binding protein, CbfA, that interacts in vitro with a regulatory element in retrotransposon TRE5-A. We have generated a mutant strain that expresses CbfA at <5% of the wild-type level to characterize the consequences for D. discoideum cell physiology. We found that the multicellular development program leading to fruiting body formation is highly compromised in the mutant. The cells cannot aggregate and stay as a monolayer almost indefinitely. The cells respond properly to prestarvation conditions by expressing discoidin in a cell density-dependent manner. A genomewide microarray-assisted expression analysis combined with Northern blot analyses revealed a failure of CbfA-depleted cells to induce the gene encoding aggregation-specific adenylyl cyclase ACA and other genes required for cyclic AMP (cAMP) signal relay, which is necessary for aggregation and subsequent multicellular development. However, the cbfA mutant aggregated efficiently when mixed with as few as 5% wild-type cells. Moreover, pulsing cbfA mutant cells developing in suspension with nanomolar levels of cAMP resulted in induction of acaA and other early developmental genes. Although the response was less efficient and slower than in wild-type cells, it showed that cells depleted of CbfA are able to initiate development if given exogenous cAMP signals. Ectopic expression of the gene encoding the catalytic subunit of protein kinase A restored multicellular development of the mutant. We conclude that sensing of cell density and starvation are independent of CbfA, whereas CbfA is essential for the pattern of gene expression which establishes the genetic network leading to aggregation and multicellular development of D. discoideum.

Download Full-text

Interaction of C4-binding protein with cell-bound C4b. A quantitative analysis of binding and the role of C4-binding protein in proteolysis of cell-bound C4b.

Journal of Experimental Medicine ◽

10.1084/jem.157.4.1239 ◽

1983 ◽

Vol 157 (4) ◽

pp. 1239-1251 ◽

Cited By ~ 29

Author(s):

T Fujita ◽

N Tamura

Keyword(s):

Cell Surface ◽

Binding Protein ◽

Fluid Phase ◽

Radioactive Tracer ◽

Scatchard Analysis ◽

Dependent Manner ◽

Alpha Chain ◽

Tracer Techniques ◽

Dose Dependent

Purified C4-binding protein (C4-bp) was shown to bind to cell-bound C4b by radioactive tracer techniques. With EAC4 bearing greater than 3,000 C4b-molecules/cell, the number of C4-bp molecules bound was directly proportional to the number of C4b molecule on the cell surface; EAC4 bearing less than 3,000 C4b-molecules/cell bound a very small amount of C4-bp. Scatchard analysis of binding of C4-bp indicated an equilibrium constant of 4.6 X 10(8) L/M and a maximum of 0.43 C4-bp molecules bound per C4b molecule, equivalent to an average of one molecule of C4-bp per two or three molecules of C4b. Fluid-phase C4b inhibited the binding of C4-bp to cell-bound C4b in a dose-dependent manner, whereas native C4 had little effect. C2 inhibited this binding and also released C4-bp from EAC4,C4-bp. However, C2 was 27 times less effective than unlabeled C4-bp on a molar basis and a considerable amount of C4-bp remained bound to C4b on the cell surface even in the presence of a large excess of C2. We also examined the cofactor activity of C4-bp in the cleavage of cell-bound C4b by C3b/C4b inactivator (I). Cleavage of the alpha' chain of C4b on the cell surface by I alone was incomplete and an intermediate cleavage product, alpha-75, was observed. When C4-bp bound to C4b on the cell surface, the alpha' chain of the C4b cleaved into three fragments, alpha 2, alpha 3, and alpha 4. The alpha 3, alpha 4, beta, and gamma peptides (C4c) were released into the fluid phase, and the alpha 2 fragment (C4d) remained linked covalently to the cell membrane via an ester bond. In some situations, therefore, C4-bp enhances the proteolytic activity of I on cell-bound C4b.

Download Full-text

Tyrosine Phosphorylation Enhances ITIM-Dependent Internalization of CD33, the Target for the Anti-AML Immunoconjugate, Gemtuzumab Ozogamicin.

Blood ◽

10.1182/blood.v108.11.2581.2581 ◽

2006 ◽

Vol 108 (11) ◽

pp. 2581-2581

Author(s):

Roland B. Walter ◽

Brian W. Raden ◽

Irwin D. Bernstein ◽

Jonathan A. Cooper

Keyword(s):

Cell Surface ◽

Tyrosine Kinase ◽

Gene Silencing ◽

Tyrosine Phosphorylation ◽

Cell Lines ◽

Myeloid Cell ◽

Gemtuzumab Ozogamicin ◽

Dependent Manner ◽

Wild Type ◽

Phosphorylation State

Abstract Background: CD33, the target for the anti-AML immunoconjugate, gemtuzumab ozogamicin (GO; Mylotarg™), contains two cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIMs). We have previously shown that these motifs control uptake of antibody-bound CD33 and GO-induced cytotoxicity. In this study, we determined which phosphorylation state favors uptake of antibody-bound CD33, identified proteins that bind to CD33 in an ITIM-dependent manner, and assessed their importance for CD33 internalization by siRNA-based gene silencing. Methods: Internalization of anti-CD33 antibodies was measured by flow cytometry in the presence or absence of the tyrosine phosphatase inhibitor, pervanadate, in human CD33+ AML cell lines (ML-1, HL-60, NB4, U937, TF-1) and CD33− Jurkat T cells infected with wild-type and mutant CD33. Pull-down experiments were performed with glutathione S-transferase (GST) proteins fused to phosphorylated cytoplasmic tails of CD33, using human myeloid cell lysates. Co-immunoprecipitations were performed with myeloid cell lines expressing HA-tagged wild-type CD33. Lentivirus-based siRNA constructs were generated for gene silencing, and expressed in human CD33+ AML cell lines. Results: Pervanadate significantly increased uptake of anti-CD33 antibodies in human AML cell lines; this effect was dependent upon the integrity of the ITIMs and was prevented by co-treatment with the Src tyrosine kinase inhibitor PP2, suggesting that Src family kinase-dependent phosphorylation of the ITIMs critically controls uptake of antibody-bound CD33, possibly by altering which proteins binds to CD33 or by facilitating binding of adaptor-proteins required for endocytosis. We identified several proteins, including the tyrosine phophatases, SHP-1 and SHP-2, and the non-receptor tyrosine kinase, Syk, which bound to phosphorylated wild-type and mutant CD33 in a manner that paralleled the endocytic properties of the corresponding CD33 protein. Since these three proteins have been implicated in endocytic processes of other cell surface proteins, we assessed their role in uptake of antibody-bound CD33 by siRNA-mediated gene silencing. Simultaneous depletion of SHP-1 and SHP-2, but not SHP-1 or SHP-2 alone, significantly increased internalization of antibody-bound CD33 in the two AML cell lines with the highest cell surface expression of CD33, whereas no effect was seen in two other cell lines with lower CD33 expression levels. In contrast, depletion of Syk, whose expression has previously been correlated to the inhibitory effect of anti-CD33 antibodies on AML cell growth, failed to affect antibody internalization in the cell lines assessed. Conclusion: These studies indicate that the phosphorylation status of the ITIMs controls uptake of antibody-bound CD33. In line with this model, SHP-1 and SHP-2, which have been shown to dephosphorylate CD33 in vitro, can affect this endocytic process. Thus, our data imply manipulation of the phosphorylation state of CD33, e.g. by activating Src family kinases or interfering with phosphatases as a novel means to increase uptake of anti-CD33 antibody-based therapeutics such as GO. Finally, the variable effect of SHP-1 and SHP-2 depletion suggests that there are significant cell-type specific differences in the response to anti-CD33 antibody ligation, for example differences in tyrosine phosphorylation levels and/or activation/recruitment or redundancies of tyrosine phosphatases.

Download Full-text

Choline Induces Transcriptional Repression and Proteasomal Degradation of the Malarial Phosphoethanolamine Methyltransferase

Eukaryotic Cell ◽

10.1128/ec.00229-07 ◽

2007 ◽

Vol 6 (9) ◽

pp. 1618-1624 ◽

Cited By ~ 18

Author(s):

William Harold Witola ◽

Choukri Ben Mamoun

Keyword(s):

Transcriptional Repression ◽

Morphological Changes ◽

Transcriptional Level ◽

Dependent Manner ◽

Wild Type ◽

Active Synthesis ◽

Rapid Multiplication ◽

Gene And Protein Expression ◽

Transgenic Parasites ◽

Dose Dependent

ABSTRACT During its intraerythrocytic life cycle, the malaria parasite Plasmodium falciparum undergoes dramatic metabolic and morphological changes and multiplies to produce up to 36 new daughter parasites. This rapid multiplication of the parasite requires an active synthesis of new membranes. The major component of these membranes, phosphatidylcholine, is synthesized via two metabolic routes, the CDP-choline pathway, which uses host choline as a precursor, and the plant-like serine decarboxylase-phosphoethanolamine methyltransferase (SDPM) pathway, which uses host serine as a precursor. Here we provide evidence indicating that the activity of the SDPM pathway is regulated by the CDP-choline precursor, choline. We show that the phosphoethanolamine methyltransferase, Pfpmt, a critical enzyme in the SDPM pathway, is down-regulated at the transcriptional level as well as targeted for degradation by the proteasome in the presence of choline. Transcript analysis revealed that PfPMT transcription is repressed by choline in a dose-dependent manner. Immunoblotting, pulse-chase experiments, and immunoprecipitation studies demonstrated that Pfpmt degradation occurs not only in wild-type but also in transgenic parasites constitutively expressing Pfpmt. The proteasome inhibitor bortezomib inhibited choline-mediated Pfpmt degradation. These data provide the first evidence for metabolite-mediated transcriptional and proteasomal regulation in Plasmodium and will set the stage for the use of this system for conditional gene and protein expression in this organism.

Download Full-text

Genetic or Enzymatic Disruption of Aromatase Inhibits the Growth of Ectopic Uterine Tissue

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.87.7.8683 ◽

2002 ◽

Vol 87 (7) ◽

pp. 3460-3466 ◽

Cited By ~ 34

Author(s):

Zongjuan Fang ◽

Sijun Yang ◽

Bilgin Gurates ◽

Mitsutoshi Tamura ◽

Evan Simpson ◽

...

Keyword(s):

Enzyme Activity ◽

Mouse Model ◽

Lesion Size ◽

Dependent Manner ◽

Wild Type ◽

Uterine Tissue ◽

Abdominal Organs ◽

Letrozole Treatment ◽

Key Enzyme ◽

Dose Dependent

Aromatase P450 (P450arom) is the key enzyme for the biosynthesis of estrogen that is essential for the growth of human endometriosis, a pathology characterized by endometrium-like tissue on the peritoneal surfaces of abdominal organs manifest by pelvic pain and infertility. Surgically transplanted autologous uterine tissue to ectopic sites on the peritoneum in mice has been used as an animal model to study endometriosis. Using this mouse model, we evaluated the roles of the P450arom gene and aromatase enzyme activity in the growth of endometriosis represented by ectopic uterine tissues in mice. Endometriosis was induced surgically in the following groups of mice: 1) untreated transgenic mice with disrupted P450arom gene (ArKO); 2) ArKO mice treated with systemic estrogen; 3) untreated wild-type (WT) mice; 4) WT mice treated with estrogen; 5) WT mice treated with the aromatase inhibitor, letrozole; and 6) WT mice treated with letrozole and estrogen. Each group contained eight mice; +/+ littermates of ArKO mice were used as WT controls. Treatment with estrogen increased the size of ectopic uterine tissues in ArKO and WT mice significantly. The ectopic uterine lesions in untreated and estrogen-treated ArKO mice were strikingly smaller than those in untreated and estrogen-treated WT controls, respectively. Systemic treatment of WT mice with letrozole significantly decreased the lesion size in a dose-dependent manner. The addition of estrogen to letrozole treatment increased the ectopic lesion size, although these lesions were significantly smaller than those in mice treated with estrogen only. As tissue controls, the effects of these conditions on normally located (eutopic) uterine tissue were evaluated. The effects of disruption of the P450arom gene and treatments with letrozole and estrogen seemed to be more profound on ectopic tissues, suggesting that ectopic tissues might be more sensitive to estrogen for growth. We conclude that both an intact P450arom gene and the presence of aromatase enzyme activity are essential for the growth of ectopic uterine tissue in a mouse model of endometriosis.

Download Full-text

Platelet endothelial cell adhesion molecule-1 is a negative regulator of platelet-collagen interactions

Blood ◽

10.1182/blood.v98.5.1456 ◽

2001 ◽

Vol 98 (5) ◽

pp. 1456-1463 ◽

Cited By ~ 87

Author(s):

Karen L. Jones ◽

Sascha C. Hughan ◽

Sacha M. Dopheide ◽

Richard W. Farndale ◽

Shaun P. Jackson ◽

...

Keyword(s):

Cell Adhesion Molecule ◽

Collagen Matrix ◽

Negative Regulator ◽

Dependent Manner ◽

Wild Type ◽

Platelet Endothelial Cell Adhesion ◽

Cell Adhesion Molecule 1 ◽

Dose Dependent ◽

Deficient Mice ◽

Endothelial Cell Adhesion

The functional importance of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) in platelets is unclear. Because PECAM-1 represents a newly assigned immunoglobulin–ITIM superfamily member expressed on the surface of platelets, it was hypothesized that it may play an important regulatory role in modulating ITAM-bearing receptors such as collagen (GP)VI receptor and FcγRIIA. To examine the functional role of PECAM-1 in regulating platelet-collagen interactions, 2 different approaches were applied using recombinant human PECAM-1–immunoglobulin chimeras and platelets derived from PECAM-1–deficient mice. Stimulation of platelets by collagen-, (GP)VI-selective agonist, collagen-related peptide (CRP)–, and PECAM-1–immunoglobulin chimera induced tyrosine phosphorylation of PECAM-1 in a time- and dose-dependent manner. Activation of PECAM-1 directly through the addition of soluble wild-type PECAM-1–immunoglobulin chimera, but not mutant K89A PECAM-1–immunoglobulin chimera that prevents homophilic binding, was found to inhibit collagen- and CRP-induced platelet aggregation. PECAM-1–deficient platelets displayed enhanced platelet aggregation and secretion responses on stimulation with collagen and CRP, though the response to thrombin was unaffected. Under conditions of flow, human platelet thrombus formation on a collagen matrix was reduced in a dose-dependent manner by human PECAM-1–immunoglobulin chimera. Platelets derived from PECAM-1–deficient mice form larger thrombi when perfused over a collagen matrix under flow at a shear rate of 1800 seconds−1 compared to wild-type mice. Collectively, these results indicate that PECAM-1 serves as a physiological negative regulator of platelet-collagen interactions that may function to negatively limit growth of platelet thrombi on collagen surfaces.

Download Full-text