Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FACTOR XI”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1997

Comparison of in vitro function of neutrophils from cattle deficient in plasma factor XI activity and from normal animals.

Cattle, homozygous for the genetic disorder of factor XI (FXI) deficiency, exhibit less than 2% of normal plasma FXI activity, display an increased bleeding tendency and are more prone to infectious diseases. FXI is one of the protein components of the contact activation system of coagulation that assembles on the surface of circulating neutrophils. Because of the central role of neutrophils in inflammation, the in vitro responses of neutrophils from normal and FXI deficient cattle were compared. Neutrophil degranulation was evaluated by measuring the release of myeloperoxidase and alkaline phosphatase, and the respiratory burst was evaluated by determining superoxide anion production. Neutrophils from FXI deficient animals exhibited a significant increase (P < 0.05) in the spontaneous release of granule contents compared to the cells from normal cattle. Following stimulation with C5a complement derived from normal serum, the neutrophils from the FXI deficient animals exhibited a greater increase (P < 0.05) in both alkaline phosphatase release and superoxide production. In these neutrophils, following stimulation with C3b complement from normal serum, the relative increase in myeloperoxidase release compared to the unstimulated neutrophils was lower than that observed in the neutrophils from normal animals. There was minimal superoxide production in unactivated neutrophils from either normal or FXI deficient cattle and the response to phorbol ester stimulation was similar in both groups of animals. The C5a complement from FXI deficient serum was more effective (P < 0.05) in stimulating alkaline phosphatase release and superoxide production in normal neutrophils than the equivalent fraction from FXI deficient serum while the C3b complement from the FXI deficient serum was less effective than the normal serum fraction at inducing myeloperoxidase release from normal neutrophils. The results indicate that the differences in the in vitro neutrophil function are likely related to a variation in the function of the contact activation system on the neutrophil surface between normal and FXI deficient animals.

Animals↗
PubMed2001

Roles of platelets and factor XI in the initiation of blood coagulation by thrombin.

To account for the variable hemostatic defect in patients with factor XI (FXI) deficiency, with normal hemostasis in contact factor deficiencies, a coagulation paradigm is presented whereby trace quantities of thrombin, generated transiently by exposure of tissue factor at sites of vascular injury, activates FXI bound to the platelet surface in the presence of prothrombin or high Mr kininogen (HK). Tissue factor pathway inhibitor (TFPI) limits the flux of thrombin generated by the tissue factor pathway, and protease nexin II (PNII), released from activated platelets, inhibits solution phase FXIa and localizes FIX activation to the platelet surface where FXIa is protected from inactivation by PNII. Either prothrombin or HK binds to the Apple 1 (A1) domain of FXI, thereby exposing a platelet-binding site in the FXI A3 domain. Dimeric FXI binds to activated platelets directly through the A3 domain of one monomer. After proteolytic activation of platelet-bound FXI by thrombin (or FXIIa), a substrate binding site for FIX is exposed in the opposite monomer that promotes FIX activation on the platelet surface resulting in the local explosive generation of thrombin and the formation of hemostatic thrombi at sites of vascular injury.

Blood Coagulation↗
PubMed1975

A new method for the assay of factor XI in plasma and the preparation and use of a new artificial substrate.

An improved method for the one-stage assay of factor XI in plasma has been proposed; it is reproducible and compares well with an old, established method.A short investigation into the preparation and use of artificially prepared factor XI-deficient plasma has been carried out: this substrate can be used as an alternative to the congenitally deficient substrate.

Analysis of Variance↗
PubMed1999

Factor XI messenger RNA in human platelets.

The bleeding diathesis associated with congenital deficiency of factor XI (FXI) is variable and correlates poorly with standard coagulation assays. Platelets are reported to contain FXI activity that may substitute for the plasma protein. The presence of this platelet activity in some patients deficient in plasma FXI could partly explain the variable bleeding associated with the deficiency state. Polyclonal antibodies to plasma FXI recognize a 220 kD platelet membrane protein distinct in structure from plasma FXI. The messenger RNA (mRNA) coding for this protein has been postulated to be an alternatively spliced FXI message lacking the fifth exon found in the liver (wild type) message. We analyzed RNA from platelets, leukocytes, and bone marrow for FXI mRNA by reverse transcription polymerase chain reaction (RT-PCR) technology. Single FXI mRNA species were identified by RT-PCR in platelet and bone marrow RNA, but not leukocyte RNA, that are the same size as the message from liver RNA. Sequencing of PCR products confirmed that the FXI mRNA species in platelets is identical to the one in liver. Wild-type FXI mRNA was also identified in three leukemia cell lines with megakaryocyte features (MEG-01, HEL 92.1.7, and CHRF-288-11). The data show that platelets contain wild-type FXI mRNA. FXI protein, therefore, may be present in platelets and may be released during platelet activation. The data do not support the premise that the 220 kD platelet protein that cross-reacts with FXI antibodies is a product of an alternatively spliced mRNA from the FXI gene.

Alternative Splicing↗
PubMed1990

Factor XI deficiency disclosed following haemorrhage related to a dental extraction. Brief review and case report.

Factor XI deficiency is a relatively common hereditary coagulation disorder manifested generally as diffuse oozing from a surgical site. Dentists may be the first to discover this deficiency and other coagulopathies after simple tooth extraction. A case is reported which illustrates a typical presentation of this disorder. The need for haematological examination and special dental care is discussed.

Factor XI Deficiency↗
PubMed1999

[Factor XI].

Explore the source record for details and available documents.

Factor XI↗
PubMed1995

[Factor XI].

Explore the source record for details and available documents.

Factor XI↗
PubMed1982

Circulating anticoagulant against factor XI in psoriasis.

A 56 year old white man with psoriasis without serologic evidence of systemic lupus erythematosus was found to have a circulating anticoagulant against Factor XI with a low activity of Factor IX which could not be fully explained. The activity of the circulating anticoagulant was not potentiated on incubation after addition of normal plasma and it was still persisting after 15 months despite periodic treatment with methotrexate and topical steroid creams. This acquired anticoagulant neither protected the patient from myocardial infarction nor produced any bleeding complications.

Blood Coagulation Disorders↗
PubMed2004

Factor XI interacts with the leucine-rich repeats of glycoprotein Ibalpha on the activated platelet.

Factor XI (FXI) binds specifically and reversibly to high affinity sites on the surface of stimulated platelets (Kd app of approximately 10 nm; Bmax of approximately 1,500 sites/platelet) utilizing residues exposed on the Apple 3 domain in the presence of high molecular weight kininogen and Zn2+ or prothrombin and Ca2+. Because the FXI receptor in the platelet membrane is contained within the glycoprotein Ibalpha subunit of the glycoprotein Ib-IX-V complex (Baglia, F. A., Badellino, K. O., Li, C. Q., Lopez, J. A., and Walsh, P. N. (2002) J. Biol. Chem. 277, 1662-1668), we utilized mocarhagin, a cobra venom metalloproteinase, to generate a fragment (His1-Glu282) of glycoprotein Ibalpha that contains the leucine-rich repeats of the NH2-terminal globular domain and excludes the macroglycopeptide portion of glycocalicin, the soluble extracytoplasmic portion of glycoprotein Ibalpha. This fragment was able to compete with FXI for binding to activated platelets (Ki of 3.125 +/- 0.25 nm) with a potency similar to that of intact glycocalicin (Ki of 3.72 +/- 0.30 nm). However, a synthetic glycoprotein Ibalpha peptide, Asp269-Asp287, containing a thrombin binding site had no effect on the binding of FXI to activated platelets. Moreover, the binding of 125I-labeled thrombin to glycocalicin was unaffected by the presence of FXI at concentrations up to 10(-5) m. The von Willebrand factor A1 domain, which binds the leucine-rich repeats, inhibited the binding of FXI to activated platelets. Thus, we examined the effect of synthetic peptides of each of the seven leucine-rich repeats on the binding of 125I-FXI to activated platelets. All leucine-rich repeat (LRR) peptides derived from glycoprotein Ibalpha were able to inhibit FXI binding to activated platelets in the following order of decreasing potency: LRR7, LRR1, LRR4, LRR5, LRR6, LRR3, and LRR2. However, the leucine-rich repeat synthetic peptides derived from glycoprotein Ibbeta and Toll protein had no effect. We conclude that FXI binds to glycoprotein Ibalpha at sites comprising the leucine-rich repeat sequences within the NH2-terminal globular domain that are separate and distinct from the thrombin-binding site.

Amino Acid Sequence↗
PubMed1977

Myositis ossificans traumatica. Association with hemophilia (factor XI deficiency) in a football player.

A case report of an outstanding college football halfback with partial factor XI deficiency, recurrent ecchymosis, and myositis ossificans is reviewed. The association of multiple areas of myositis ossificans and partial clotting-factor deficiency has not been noted in the past. The importance of considering this diagnosis in participants in contact sports with the above findings is emphasized.

Adult↗
PubMed1983

Factor XI deficiency and a platelet defect.

A patient with a lifelong bleeding tendency of moderate severity was found to have both factor XI deficiency and a long bleeding time. There was a significant deficiency of platelet factor 3, but other parameters of platelet function were normal. Infusion studies showed that both fresh plasma and platelet concentrate were required for complete correction of the haemostatic abnormalities, suggesting that these two defects were inherited coincidentally.

Adult↗
PubMed2003

Eighteen unrelated patients with factor XI deficiency, four novel mutations and a 100% detection rate by denaturing high-performance liquid chromatography.

Factor XI (FXI) deficiency is an autosomal bleeding disorder of variable severity. Inheritance is not completely recessive as heterozygotes may display a distinct, if mild, bleeding tendency. Eighteen unrelated FXI-deficient patients were screened blind by fluorescent single-stranded conformation polymorphism (F-SSCP) analysis and denaturing high-performance liquid chromatography (dHPLC). Mutations were detected in 14 of the 18 patients ( approximately 78%) by F-SSCP and in all 18 patients by dHPLC. Dideoxy sequencing confirmed the mutations in all 18 patients: eight of the mutations being novel (four of which were in previously reported patients). This showed dHPLC to be a highly sensitive, reliable technique for mutation screening in heterogeneous disorders.

Chromatography, High Pressure Liquid↗