scholarly journals Increased Thrombophilic Tendency in Pediatric Cystic Fibrosis Patients

2009 ◽  
Vol 16 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Vaughan Williams ◽  
Adrian B. M. Griffiths ◽  
Zen L. Yap ◽  
James Martin ◽  
Gregory Smith ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
General Population ◽  
Protein C ◽  
Activated Protein C ◽  
Protein S ◽  
Activated Protein C Resistance ◽  
Antithrombin Deficiency ◽  
Indwelling Catheters ◽  
C Protein ◽  
Lupus Anticoagulants

Thrombophilia has recently been reported to be increased in patients with cystic fibrosis (CF). We wanted to determine whether this was applicable to our population with CF and how our patients compared to the previously reported groups. Seventy one pediatric CF patients were assessed for a thrombophilic tendency, using a lupus anticoagulant screen, protein C, protein S, antithrombin assay, and activated protein C resistance (APCR) screen. The incidence of activate protein C resistance (4.2%) was within expected limits for the general population as was the incidence of antithrombin deficiency. However there was a marked increase in the incidence of lupus anticoagulants (18%) and 14% and 19.7% of the patients showed a reduced protein C and protein S, respectively, far in excess of the general population. This increased incidence of thrombophilia was not related to any specific CF phenotype and while perturbed liver function cannot be entirely ruled out, it appeared unlikely to be responsible for all the abnormal coagulation findings. Despite the apparent thrombophilic tendency, no clinically evident thrombotic episodes were noted during the study period. Thrombophilia is of concern because of the increasingly frequent placement of indwelling catheters in CF patients. The precise cause for the thrombophilic tendency in CF patients is unknown at this stage.

Acquired activated protein C resistance is associated with lupus anticoagulants and thrombotic events in pediatric patients with systemic lupus erythematosus

Blood ◽  
2001 ◽  
Vol 97 (4) ◽  
pp. 844-849 ◽  
Author(s):  
Christoph Male ◽  
Lesley Mitchell ◽  
James Julian ◽  
Patricia Vegh ◽  
Penny Joshua ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Lupus Erythematosus ◽  
Protein C ◽  
Pediatric Patients ◽  
Activated Protein C ◽  
Factor V Leiden ◽  
Protein S ◽  
Activated Protein C Resistance ◽  
Systemic Lupus ◽  
Lupus Anticoagulants

Abstract Acquired activated protein C resistance (APCR) has been hypothesized as a possible mechanism by which antiphospholipid antibodies (APLAs) cause thrombotic events (TEs). However, available evidence for an association of acquired APCR with APLAs is limited. More importantly, an association of acquired APCR with TEs has not been demonstrated. The objective of the study was to determine, in pediatric patients with systemic lupus erythematosus (SLE), whether (1) acquired APCR is associated with the presence of APLAs, (2) APCR is associated with TEs, and (3) there is an interaction between APCR and APLAs in association with TEs. A cross-sectional cohort study of 59 consecutive, nonselected children with SLE was conducted. Primary clinical outcomes were symptomatic TEs, confirmed by objective radiographic tests. Laboratory testing included lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), APC ratio, protein S, protein C, and factor V Leiden. The results revealed that TEs occurred in 10 (17%) of 59 patients. Acquired APCR was present in 18 (31%) of 58 patients. Acquired APCR was significantly associated with the presence of LAs but not ACLAs. Acquired APCR was also significantly associated with TEs. There was significant interaction between APCR and LAs in the association with TEs. Presence of both APCR and LAs was associated with the highest risk of a TE. Protein S and protein C concentrations were not associated with the presence of APLAs, APCR, or TEs. Presence of acquired APCR is a marker identifying LA-positive patients at high risk of TEs. Acquired APCR may reflect interference of LAs with the protein C pathway that may represent a mechanism of LA-associated TEs.

scholarly journals Prevalence of common thrombophilia markers and risk factors in Indian patients with primary venous thrombosis

2010 ◽  
Vol 128 (5) ◽  
pp. 263-267 ◽  
Author(s):  
Mahendra Narain Mishra ◽  
Varinder Singh Bedi
Keyword(s):  
Venous Thrombosis ◽  
Protein C ◽  
Quantitative Estimation ◽  
Protein S ◽  
Anticardiolipin Antibodies ◽  
Factor V ◽  
Cross Sectional ◽  
C Protein ◽  
Lupus Anticoagulants ◽  
Significant Difference

CONTEXT AND OBJECTIVE: Venous thrombosis occurs as a result of interaction of genetic and acquired factors including activated protein C resistance (APC-R), fibrinogen levels, antithrombin, protein C, protein S, lupus anticoagulants and anticardiolipin antibodies. This study was aimed at determining the prevalence of these common thrombophilia markers in Asian Indians with primary venous thrombosis. DESIGN AND SETTING: This was a cross-sectional study carried out in Mumbai. METHODS: Samples from 78 patients with a confirmed diagnosis of venous thrombosis and 50 controls were tested. Semi-quantitative estimation (functional assays) of protein C, protein S and antithrombin was performed. Quantitative estimation of fibrinogen was done using the Clauss method. Lupus anticoagulants were screened using lupus-sensitive activated partial thromboplastin time and β2-glycoprotein-I dependent anticardiolipin antibodies were estimated by ELISA. APC-R was measured using a clotting-based method with factor V deficient plasma and Crotalus viridis venom. Statistical analysis was performed using Epi-info (version 6). RESULTS: The popliteal vein was the most commonly involved site. Forty-four samples (56%) gave abnormal results. The commonest were elevated fibrinogen and APC-R (17.9% each), followed by low protein S (16.6%). CONCLUSIONS: This study confirms the literature findings that fibrinogen level estimation and screening for APC-R are important for the work-up on venous thrombosis patients since these, singly or in combination, may lead to a primary thrombotic episode. The frequency of the other thrombophilia markers was higher among the patients than among the controls, but without statistically significant difference.

ENDOTHELIUM AND PROTEIN S: SYNTHESIS, RELEASE AND REGULATION OF ANTICOAGULANT ACTIVITY

1987 ◽  
Author(s):  
Peter P Nawroth ◽  
Jerry Brett ◽  
Susan Steinberg ◽  
Charles T Esmon ◽  
David M Stern
Keyword(s):  
Endothelial Cell ◽  
Protein C ◽  
Specific Binding ◽  
Activated Protein C ◽  
Protein S ◽  
Intracellular Protein ◽  
C Protein ◽  
Factor Va ◽  
Intracellular Vesicles ◽  
Anticoagulant Function

The protein C-protein S pathway is closely linked to the vessel wall. In terms of protein C, endothelium has been shown to provide the receptor thrombomodulin, which promotes thrombin-mediated formation of activated protein C. Optimal anticoagulant function of activated protein C requires protein S and a cellular surface. Recent studies have indicated that endothelium can facilitate assembly of the activated protein C-protein S complex and that bovine endothelium expresses specific binding site(s) for protein S which promote its anticoagulant function. Expression of protein S binding sites is subject to down-regulation by Tumor Necrosis Factor (TNF) . Exposure of cultured bovine endothelium to TNF results in decreased 125I-protein s binding and attenuated rates of Factor Va inactivation after 2 hrs followed by negligible 125I-protein S binding and Factor Va inactivation by 10 hrs. These changes persist for over 48 hrs, in contrast to the more transient rise in endothelial cell tissue factor induced by TNF which returns to baseline by 24 hrs.In addition to providing binding sites for protein S, endothelium constitutively synthesizes and releases this vitamin K-dependent anticoagulant cofactor. Release of protein S is blocked by addition of warfarin, indicating that y-carboxylation facilitates the release of intracellular protein S. Morphologic studies, at the level of electron microscope, have shown protein S antigen to be present in cisternae of rough endoplasmic reticulum, the trans face of the golgi and a population of intracellular vesicles which appear to be distributed at the cellular periphery. By immunofluorescence, the distribution of protein S is distinct from that of von Willebrand Factor. The intracellular vesicles containing protein S constitute a storage pool potentially available for rapid release. Treatment of endothelium with norepinephrine results in release of protein S over the next 20 min. Release is half-maximal at a norepinephrine concentration of about 0.1 uM and is not observed with the biologically inactive entantiomer (+) norepinephrine. Norepinephrine-induced release of intracellular protein S can be blocked by prazosine (10-7 7 M), but not by propranolol (10-6 M) or yohimbine (10-5 M). These data are consistent with release of protein S being a receptor-mediated process dependent on an endothelial cell alpha 1 adrenergic receptor. Blockade of norepinephrine-induced release of protein S by pertussis toxin treatment of endothelium further defines the intracellular pathway of protein S and implicates regulatory G proteins in the stimulus-response coupling. Electron microscopic studies have shown that following exposure of endothelium to norepinephrine the intracellular vesicles containing protein S undergo exocytosis at the plasma membrane. These data define a new relationship between the autonomic nervous system and the coagulation mechanism.Protein S is clearly an endothelial cell-associated anticoagulant protein. A specific binding site on the endothelial cell surface can regulate its anticoagulant function on the vessel wall. Endothelial cell synthesis and release of protein S defines a new level of participation of endothelium in the protein C-protein S pathway.

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