Gines Escolar

A randomized controlled clinical trial evaluating the performance and safety of platelets treated with MIRASOL pathogen reduction technology

BACKGROUND: Pathogen reduction of platelets (PRT‐PLTs) using riboflavin and ultraviolet light treatment has undergone Phase 1 and 2 studies examining efficacy and safety. This randomized controlled clinical trial (RCT) assessed the efficacy and safety of PRT‐PLTs using the 1‐hour corrected count increment (CCI1hour) as the primary outcome.

Effects of human monoclonal anticardiolipin antibodies on platelet function and on tissue factor expression on monocytes

OBJECTIVE To investigate the effect of human monoclonal anticardiolipin antibodies (aCL) on platelet interaction with the subendothelium under flow conditions and on tissue factor (TF) expression on normal monocytes. METHODS Three monoclonal IgM aCL (TM1B3, GR1D5, and EY2C9) and 2 affinity-purified IgM aCL were studied. Immunoglobulins were added to normal blood and perfused through chambers containing denuded vascular segments. Platelet interactions were morphometrically evaluated by determining the percentage of total surface covered by platelets (PCS) or by large aggregates of thrombi platelets (TP). Expression of TF on monocytes was measured after immunoglobulin incubation with normal mononuclear cells. RESULTS Significant increases in the total PCS and expression of TF were observed using all aCL. Increased levels of TP were induced by all aCL except EY2C9 (obtained from a patient without thrombosis). Previous incubations of these aCL with subendothelial surfaces did not increase platelet interaction. CONCLUSION The effects of aCL on platelet function may help to explain the pathophysiology of thrombosis in the antiphospholipid syndrome.

Experimental basis for the use of red cell transfusion in the management of anemic-thrombocytopenic patients

The Baumgartner perfusion technique was used as an experimental model to study the combined influence of red cell (RBC) and platelet counts on the interaction of platelets with the subendothelium. At normal hematocrit and a platelet count of 100,000 per microliter, platelet adhesion and platelet aggregate (PAG) formation on subendothelium were statistically decreased. At lower platelet counts (50,000/μliter), there was an even more marked reduction in the formation of PAGs. The critical role of RBCs was demonstrated in experiments at low hematocrit; the formation of PAGs was impaired in perfusions at 20 percent hematocrit at any platelet count tested. Platelet deposition on subendothelium was almost absent at 50,000 platelets per μliter, suggesting a negative synergistic effect for the association of low hematocrit (20%) with a low platelet count. Perfusion experiments carried out with nonanticoagulated blood drawn directly from anemic patients with mild thrombocytopenia (43,000–58,000 platelets/μliter) before and after RBC transfusion were in agreement with previous experiments that indicated that normalization of both platelet count and hematocrit is required to achieve optimum hemostasis. Our data give experimental support for the transfusional management of patients with anemia and thrombocytopenia.

Hypercoagulable State in Patients With Antiphospholipid Syndrome Is Related to High Induced Tissue Factor Expression on Monocytes and to Low Free Protein S

Antiphospholipid antibodies (aPLs) are associated with thrombosis, but the mechanisms of this thrombotic tendency are unknown. We studied 56 patients 612 with systemic lupus erythematosus [SLE] and aPLs and previous thrombosis, 12 with SLE and aPLs but no thrombosis, 15 with SLE without aPLs or thrombosis, 11 with primary antiphospholipid syndrome with thrombosis, and 6 asymptomatic subjects with aPLs) to investigate the ability of aPLs to induce tissue factor (TF) expression on human normal monocytes. A double direct immunofluorescence technique (anti-CD14 and anti-TF) was used, and procoagulant activity in viable and disrupted cells was measured after plasma incubation for 6 hours at 37 degrees C with normal mononuclear cells. Hemostasis regulatory proteins, prothrombin fragment 1 + 2, and thrombin-antithrombin III complex levels were determined. Increased TF expression and procoagulant activity were observed using plasma samples from SLE patients with aPLs and thrombosis (P < .01) and from primary antiphospholipid syndrome patients (P < .01) but not from patients with SLE and aPLs but no thrombosis, patients with SLE without aPLs, or asymptomatic patients with aPLs. Purified aPL immunoglobulins from one primary antiphospholipid syndrome and two SLE patients added to normal plasma showed a significant increase in both TF expression and procoagulant activity (P < .05) compared with purified aPL from two SLE patients without thrombosis. The addition of nonspecific IgG from three SLE patients without aPLs and from three control subjects did not increase TF expression. Low free protein S was seen in eight patients. Increased TF expression and low free protein S correlated with thrombosis (P < .01) and with higher prothrombin fragment 1 + 2 and thrombin-antithrombin III values (P < .01). These observations may contribute to a further understanding of the thrombotic risk in aPL patients.

Reversal of apixaban induced alterations in hemostasis by different coagulation factor concentrates: significance of studies in vitro with circulating human blood.

Apixaban is a new oral anticoagulant with a specific inhibitory action on FXa. No information is available on the reversal of the antihemostatic action of apixaban in experimental or clinical settings. We have evaluated the effectiveness of different factor concentrates at reversing modifications of hemostatic mechanisms induced by moderately elevated concentrations of apixaban (200 ng/ml) added in vitro to blood from healthy donors (n = 10). Effects on thrombin generation (TG) and thromboelastometry (TEM) parameters were assessed. Modifications in platelet adhesive, aggregating and procoagulant activities were evaluated in studies with blood circulating through damaged vascular surfaces, at a shear rate of 600 s−1. The potential of prothrombin complex concentrates (PCCs; 50 IU/kg), activated prothrombin complex concentrates (aPCCs; 75 IU/kg), or activated recombinant factor VII (rFVIIa; 270 μg/kg), at reversing the antihemostatic actions of apixaban, were investigated. Apixaban interfered with TG kinetics. Delayed lag phase, prolonged time to peak and reduced peak values, were improved by the different concentrates, though modifications in TG patterns were diversely affected depending on the activating reagents. Apixaban significantly prolonged clotting times (CTs) in TEM studies. Prolongations in CTs were corrected by the different concentrates with variable efficacies (rFVIIa≥aPCC>PCC). Apixaban significantly reduced fibrin and platelet interactions with damaged vascular surfaces in perfusion studies (p<0.05 and p<0.01, respectively). Impairments in fibrin formation were normalized by the different concentrates. Only rFVIIa significantly restored levels of platelet deposition. Alterations in hemostasis induced by apixaban were variably compensated by the different factor concentrates investigated. However, effects of these concentrates were not homogeneous in all the tests, with PCCs showing more efficacy in TG, and rFVIIa being more effective on TEM and perfusion studies. Our results indicate that rFVIIa, PCCs and aPCCs have the potential to restore platelet and fibrin components of the hemostasis previously altered by apixaban.

Effects of a new pathogen-reduction technology (Mirasol PRT) on functional aspects of platelet concentrates.

BACKGROUND: Several strategies are being developed to reduce the risk of pathogen transmission associated with platelet (PLT) transfusion.

Efficacy of eculizumab in the treatment of recurrent atypical hemolytic-uremic syndrome after renal transplantation.

REFERENCES 1. Tilney N, Murray J, Thistlethwaite R, et al. Promotion of altruistic donation. Transplantation 2009; 88: 847. 2. Nejatisafa AA, Mortaz-Hedjri S, Malakoutian T, et al. Quality of life and life events of living unrelated kidney donors in Iran: A multicenter study. Transplantation 2008; 86: 937. 3. Hippen B. Organ sales and moral travails: Lessons from the Living Kidney Vendor Program in Iran. Policy Analysis no 614. Washington, DC, Cato Institute 2008. 4. Ghods AJ. Renal transplantation in Iran. Nephrol Dial Transplant 2002; 17: 222. 5. Ghods AJ, Ossareh S, Khosravani P. Comparison of some socioeconomic characteristics of donors and recipients in a controlled living unrelated donor renal transplantation program. Transplant Proc 2001; 33: 2626. 6. Zargooshi J. Quality of life of Iranian kidney “donors.” J Urol 2001; 166: 1790. 7. Schold JD, Srinivas TR, Kayler LK, et al. The overlapping risk profile between dialysis patients listed and not listed for renal transplantation. Am J Transplant 2008; 8: 58.

Thrombomodulin and induced tissue factor expression on monocytes as markers of diabetic microangiopathy: A prospective study on hemostasis and lipoproteins in insulin-dependent diabetes mellitus

Vascular complications are the main cause of morbidity in diabetes mellitus. To evaluate lipoprotein and hemostatic parameters and their relationship with clinically detectable microangiopathy, we studied 58 insulin‐dependent diabetes mellitus patients and 60 controls matched for age, sex, and body mass index. Thirteen patients presented clinically detectable microangiopathy (8 retinopathy and 5 both retinopathy and microalbuminuria). A cross‐sectional study of lipid profile, coagulation parameters, and a flow‐cytometric evaluation of tissue factor expression in normal monocytes induced by patient plasma were performed. Patients were re‐evaluated for microangiopathy in a 3‐year median follow‐up. Patients showed triglyceride enrichment in low (P = 0.00002) and high density lipoproteins (P = 0.004) and increased levels of D‐dimer (P < 0.00001), prothrombin fragment 1 + 2 (P < 0.00001), and thrombin‐antithrombin III complex (P = 0.0001). Patients with clinically detectable microangiopathy had increased type 1 plasminogen activator inhibitor (P = 0.00001), thrombomodulin (P = 0.02), and induced monocyte tissue factor expression (P < 0.00001). Nine patients developed clinically detectable microangiopathy in the follow‐up and the only predictive variable was increased induced tissue factor expression. In conclusion, in these patients elevated thrombin and fibrin generation reflects a hypercoagulable state but clinically detectable microangiopathy seems related to endothelial cell injury markers and to increased induced tissue factor expression on monocytes. Am. J. Hematol. 56:93–99, 1997.

The 4G/5G polymorphism of the type 1 plasminogen activator inhibitor gene and thrombosis in patients with antiphospholipid syndrome.

OBJECTIVE To investigate the relationship between the 4G/5G polymorphism of the type 1 plasminogen activator inhibitor (PAI-1) gene and thrombotic manifestations in patients with antiphospholipid syndrome (APS). METHODS We studied a total of 247 patients included in the following 4 groups: 70 patients with primary APS, 104 patients with systemic lupus erythematosus (40 with antiphospholipid antibodies [aPL] and clinical [secondary] APS, 13 with aPL but without clinical APS, and 51 with neither detectable aPL nor a history of thrombosis), 14 asymptomatic individuals with aPL, and 59 patients with thrombosis but without known thrombosis risk factors. A control group of 100 healthy individuals was also analyzed. PAI-1 4G/5G polymorphism was determined by polymerase chain reaction and endonuclease digestion. RESULTS The allele frequency of 4G/5G in controls was 0.47/0.53. There were no differences in allele distribution among patient groups or between patients and controls. However, a higher frequency of the 4G allele was observed in APS patients with versus those without thrombosis (0.57 versus 0.39; P < 0.05) (odds ratio [OR] 2.83, 95% confidence interval [95% CI] 1.18-6.76). This higher frequency of the 4G allele was attributable to the higher frequency in patients with versus those without arterial thrombosis (0.64 versus 0.43; P < 0.01) (OR 5.96, 95% CI 1.67-21.32), while patients with venous thrombosis had an allele distribution similar to that of those without venous thrombosis (0.49 versus 0.50; P not significant). There was a trend toward higher PAI-1 antigen and activity levels in APS patients and controls with the 4G/4G genotype, but this did not reach statistical significance. CONCLUSION The presence of the 4G allele of the 4G/5G polymorphism of the PAI-1 gene may be an additional risk factor for the development of arterial thrombosis in APS.

Effects of celecoxib and naproxen on renal function in nonazotemic patients with cirrhosis and ascites

Nonselective inhibition of cyclooxygenase (COX) by nonsteroidal anti‐inflammatory drugs frequently induces renal failure in decompensated cirrhosis. Studies in experimental cirrhosis suggest that selective inhibitors of the inducible isoform COX‐2 do not adversely affect renal function. However, very limited information is available on the effects of these compounds on renal function in human cirrhosis. This investigation consists of a double‐blind, randomized, placebo‐controlled trial aimed at comparing the effects of the selective COX‐2 inhibitor celecoxib (200 mg every 12 hours for a total of 5 doses) on platelet and renal function and the renal response to furosemide (40 mg intravenously) with those of naproxen (500 mg every 12 hours for a total of 5 doses) and placebo in 28 patients with cirrhosis and ascites. A significant reduction (P < .05) in glomerular filtration rate (113 ± 27 to 84 ± 22 mL/min), renal plasma flow (592 ± 158 to 429 ± 106 mL/min) and urinary prostaglandin E2 excretion (3430 ± 430 to 2068 ± 549 pg/min) and suppression of the diuretic (urine volume: 561 ± 128 to 414 ± 107 mL/h) and natriuretic (urine sodium: 53 ± 13 to 34 ± 10 mEq/h) responses to furosemide were observed in the group of patients treated with naproxen but not in the other two groups. Naproxen, but not celecoxib or placebo, significantly inhibited platelet aggregation (72% ± 8% to 47% ± 8%, P < .05) and thromboxane B2 production (41 ± 12 to 14 ± 5 pg/mL, P < .05). In conclusion, our results indicate that short‐term administration of celecoxib does not impair platelet and renal function and the response to diuretics in decompensated cirrhosis. Further studies are needed to evaluate the long‐term safety of this drug in cirrhosis. (HEPATOLOGY 2005;41:579–587.)