Biomedical subjects

J C Reverter

Publications and source records attributed to J C Reverter.

At least 37 records · Page 2Linked to original sources

PubMed2000

Heparin attenuates TNF-alpha induced inflammatory response through a CD11b dependent mechanism.

BACKGROUND: In addition to its anticoagulant properties, heparin has anti-inflammatory effects, the molecular and mechanistic bases of which are incompletely defined. AIMS: The current studies were designed to test the hypothesis that heparin abrogates the expression or function of leucocyte-endothelial adherence molecules which are fundamental to the acute inflammatory response. METHODS: The effects of heparin on tumour necrosis factor alpha (TNF-alpha) induced leucocyte rolling, adhesion, and migration as well as vascular permeability were assessed in rat mesenteric venules using intravital microscopy. Expression of adhesion molecules was quantitated using a double radiolabelled monoclonal antibody (mAb) binding technique in vivo (P-selectin, intercellular cell adhesion molecule type 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1)) or flow cytometry (CD11a, CD11b, and L-selectin). Ex vivo binding of heparin to neutrophils was assessed by flow cytometry. RESULTS: TNF-alpha induced a significant increase in leucocyte rolling, adhesion, and migration, and vascular permeability, coincident with a significant increase in expression of P-selectin, ICAM-1, and VCAM-1. Ex vivo assessment of blood neutrophils showed significant upregulation of CD11a and CD11b and significant downregulation of L-selectin within five hours of TNF-alpha administration. Heparin pretreatment significantly attenuated leucocyte rolling, adhesion, and migration but did not affect expression of cell adhesion molecules or vascular permeability elicited by TNF-alpha administration. Binding of heparin was significantly increased on blood neutrophils obtained five hours after TNF-alpha administration. Preincubation with an anti-CD11b mAb but not with an anti-CD11a or anti-L-selectin antibody significantly diminished heparin binding ex vivo. CONCLUSIONS: Our results support the concept that the anti-inflammatory effects of heparin involve attenuation of a CD11b dependent adherent mechanism.

Animals↗

PubMed2000

Prevalence and clinical significance of antiprothrombin antibodies in patients with systemic lupus erythematosus or with primary antiphospholipid syndrome.

BACKGROUND AND OBJECTIVE: Antibodies to prothrombin (aII) have been identified in patients with antiphospholipid antibodies, but their clinical significance is not well known. The aim of our study was to investigate their prevalence and association with clinical manifestations of the antiphospholipid syndrome (APS) in patients with primary APS or with systemic lupus erythematosus (SLE). DESIGN AND METHODS: A series of 177 patients with autoimmune diseases was studied: 70 with primary APS and 107 with systemic lupus erythematosus. A control group of 87 healthy volunteers were included in the study. aII were investigated in sera by an ELISA, using human prothrombin as antigen fixed in irradiated polystyrene plates. RESULTS: aII prevalence in patients with autoimmune disease was 47% (57% and 40% in patients with primary APS or with SLE, respectively) significantly higher than in controls (5%) (p<0.0001). In the whole series, thrombotic events were more prevalent in patients with aII (45% vs 28%; p=0.02). Moreover, aII was found to be an independent risk factor for arterial thrombosis (OR=2.4; p=0. 04). Similarly, in patients with SLE, aII were associated with both arterial and venous thrombosis (35% vs 14%; p=0.01), although only IgG-aII (OR=3.7; p=0.01) had an independent value as risk factor for thrombosis. However, a relationship between aII and thrombosis was not found in primary APS. aII were associated with thrombocytopenia only in patients with primary APS (OR=6.7; p=0.007). INTERPRETATION AND CONCLUSIONS: aII seem to be a serological marker of thrombosis in autoimmune diseases, mainly in SLE patients and/or in the arterial territory.

Abortion, Spontaneous↗

PubMed1999

Ex vivo response to aspirin differs in stroke patients with single or recurrent events: a pilot study.

The dose of aspirin for secondary stroke prevention and the clinical meaning of ex vivo platelet abnormalities are debated. We assessed prospectively 39 noncardioembolic stroke patients in which 300 mg/day aspirin had proved effective (n=24) or ineffective (n=15) to prevent recurrent ischemic events. We evaluated platelet aggregation induced by arachidonic acid, adenosine diphosphate and epinephrine, and the sensitivity of platelets to increasing concentrations of the synthetic thromboxane mimetic U46619. Aggregation studies were repeated while subjects received 300 (study phase 1), and 600 (study phase 2) mg/day aspirin, respectively. Overall, arachidonic acid-induced platelet aggregation was less effectively inhibited during study phase 1 compared to phase 2. Arachidonic acid and epinephrine promoted a stronger platelet aggregation in aspirin nonresponders than in aspirin responders while taking 300 mg/day aspirin. On the other hand, 600 mg/day effectively inhibited platelet function in both clinical groups. A lower sensitivity to thromboxane receptors was also found during phase 1 of the study, although the response was similar between aspirin responders and nonresponders. This pilot study suggests that 300 mg/day aspirin is less effective than 600 mg/day to block the cyclooxygenase pathway in noncardioembolic stroke and, incomplete cyclooxygenase inhibition is associated with recurrent thromboembolic events despite adequate aspirin compliance. It is likely that patients could receive a more efficacious stroke prevention if the dose of aspirin is tailored to individual needs as reflected by laboratory findings.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1999

Assessment of potential thrombogenicity of coagulation factor IX concentrates in an in vitro model of human thrombogenesis.

We have investigated the potential use of perfusion techniques in the evaluation of the thrombogenic profile of factor IX concentrates. Blood from healthy donors was anticoagulated with low molecular weight heparin and incubated with one of the following: (a) diluent (DIL); (b) a prothrombin complex concentrate (PCC); (c) an intermediate-purity concentrate (FIX/X); or (d) a high-purity concentrate (HPFIX). The thrombogenic potential was assessed as: (1) fibrin formation on subendothelium (Baumgartner's perfusion) and (2) prothrombin activation fragment 1+2 (F1+2, nM) determination. The percentage of fibrin deposition on the subendothelium was only significantly increased after incubation with PCC (62.0+/-3.6% vs. DIL 35.0+/-6.1%;p<0.05). None of the FIX concentrates modified platelet interaction versus control blood (DIL: 26.7+/-2.1%). F1+2 baseline values in anticoagulated blood were 0.6+/-0.1 nM. Preperfusion levels of F1+2 reached values of 4.4+/-0.1 nM for PCC and 5.4+/-0.1 nM for FIX/X. After perfusion, F1+2 values were 2.7+/-0.2 nM for DIL, 5.6+/-0.1 nM for PCC and FIX/X, and 3.3+/-0.2 nM for HPFIX. While measurement of F1+2 was influenced by residual contaminants present in the concentrates, the morphometric evaluation of fibrin deposition on perfused vascular surfaces could be more closely related to the net thrombogenic profile of each FIX preparation.

Animals↗

PubMed1999

Clinical study and follow-up of 100 patients with the antiphospholipid syndrome.

OBJECTIVES: To study the clinical characteristics at diagnosis and during follow-up of patients with the antiphospholipid syndrome (APS) and to analyze the influence of treatment on their outcome. PATIENTS: One hundred patients with APS were included (86% female and 14% male; mean age, 36 years). Sixty-two percent had primary APS and 38% had APS associated with systemic lupus erythematosus (SLE). The median length of follow-up was 49 months. RESULTS: Fifty-three percent of the patients had thromboses, 52% had thrombocytopenia, and 60% of the women had pregnancy losses. Patients with APS associated with SLE had a higher prevalence of hemolytic anemia (P = .02), thrombocytopenia (platelet count lower than 100 x 10(9)/L) (P = .004), antinuclear antibodies (P = .0002), and low complement levels. Fifty-three percent of the patients with thrombosis had recurrent episodes (86% in the same site as the previous thrombotic event). Recurrences were observed in 19% of the episodes treated with long-term oral anticoagulation, in 42% treated prophylactically with aspirin, and in 91% in which anticoagulant/antiaggregant treatment was discontinued (P = .0007). Multivariate analysis showed that prophylactic treatment and older age had an independent predictive value for rethrombosis. Prophylactic treatment during pregnancy (usually with aspirin) increased the live birth rate from 38% to 72% (P = .0002). CONCLUSIONS: Patients with APS have a high risk of recurrent thromboses. Long-term oral anticoagulation seems to be the best prophylactic treatment to prevent recurrences. Prophylactic treatment with aspirin during pregnancy reduced the rate of miscarriages remarkably.

Adolescent↗

PubMed1999

Prevalence of hepatitis C virus infection in patients with antiphospholipid syndrome.

BACKGROUND/AIMS: The aim of this study was to determine the prevalence and clinical significance of hepatitis C virus (HCV) infection in patients with the antiphospholipid syndrome (APS). METHODS: A series of 88 consecutive patients (78 female and 10 male), with a mean age of 39 years (range 15-79), was prospectively studied. All patients had been diagnosed with APS: 54 (61%) primary APS and 34 (39%) APS associated with systemic lupus erythematosus. A group of 200 apparently healthly blood donors was included in the study. Anti-HCV antibodies were investigated in the serum of all patients using a third-generation ELISA and confirmed by recombinant immunoblot assay. RNA-HCV was investigated in anti-HCV positive samples by polymerase chain reaction. Anticardiolipin, anti-beta2-glycoprotein I and antiprothrombin antibodies were evaluated by ELISA. Lupus anticoagulant was studied by coagulometric assays. RESULTS: Only 2 (2.2%) patients showed positivity for anti-HCV antibodies, but none of them had clinical or biochemical signs of liver disease. Furthermore, RNA-HCV was not detected in serum of any of these patients. Lupus anticoagulant was positive in 57% of patients. Anticardiolipin antibodies were positive in 60% of patients, anti-beta2-glycoprotein I antibodies in 43% of patients, and antiprothrombin antibodies in 56% of patients. The prevalence of anti-HCV in blood donors was 1%. CONCLUSIONS: The prevalence of anti-HCV in patients with APS is low and similar to that in healthy people in our area. HCV infection does not seem to be involved in the etiopathogenesis of this syndrome.

Adolescent↗

PubMed1999

Human reproductive failure is not a clinical feature associated with beta(2) glycoprotein-I antibodies in anticardiolipin and lupus anticoagulant seronegative patients (the antiphospholipid/cofactor syndrome)

It has been suggested that patients with clinical features suggestive of antiphospholipid syndrome but being lupus anticoagulant (LA) and anticardiolipin (aCL) negative, should be tested for antibodies to beta(2) glycoprotein-I (abeta(2)GP-I), a protein involved in the binding of antiphospholipid antibodies (aPL) to phospholipid surfaces. This was investigated in the present study where a total of 385 women aged </=40 years were included. Of these, 175 were experimental subjects and 210 were controls. The former comprised the following two study groups: 100 spontaneous recurrent aborters (group one), and 75 patients with repeated failure of embryo transfer (group two). Controls included three groups of women: 100 normal healthy parous women with no previous abortion (group three), 60 infertile patients achieving a live birth with their first in-vitro fertilization (IVF)/embryo transfer attempt (group four), and 50 patients with recurrent abortion who tested positive for aPL (LA and/or aCL) (positive controls, group five). Only one patient among recurrent aborters (group one) tested positive for abeta(2)GP-I. All women in groups two, three and four were negative for abeta(2)GP-I screening. As expected, prevalence of patients testing positive for abeta(2)GP-I was significantly higher in group five than among the other groups of patients (P < 0.001). No differences were observed regarding the prevalence of abeta(2)GP-I positive sera in the subgroup of patients having aCL and those having the LA in group five. It is concluded that abeta(2)GP-I screening in first-trimester recurrent abortion or in failure of implantation after IVF is not warranted in patients without aPL as detected by standard antiphospholipid assays.

Abortion, Habitual↗

PubMed1999

Hepatitis G virus infection markers (RNA and anti-E2 antibodies) in a multicenter cohort of hemophiliacs.

BACKGROUND AND OBJECTIVE: To investigate the prevalence and evolution of hepatitis G virus (HGV) infection in hemophiliacs and to correlate evolution of HGV infection markers with immunologic parameters in those patients co-infected with HIV. DESIGN AND METHODS: HGV RNA and anti-E2 antibodies were studied in 124 patients. Serial samples were drawn every 4 months from 1992 to 1996. Lymphocyte subsets including T-helper lymphocytes, T-suppressor lymphocytes, T-cytotoxic lymphocytes, activated T-lymphocytes and natural killer cells were analyzed. RESULTS: Prevalences were 22.6% for HGV RNA and 18.5% for anti-E2. Four patients had both HGV RNA and anti E2, so the overall prevalence of HGV infection in hemophiliacs was 37.9% (11.5% in 200 controls, p<0.0001). After a median follow-up of 36.6 months 20 patients remained HGV RNA positive, whereas HGV RNA had cleared in 8, with an actuarial probability of clearance at 36 months of 34.6%. Only 2 patients developed anti-E2 antibodies. Four patients cleared anti-E2, with an actuarial probability at 36 months of 24.8%. In patients with HIV infection, both lower CD4+ lymphocyte count (p=0.01) or higher CD8+ lymphocyte count (p=0.03) showed predictive value for probability of clearing HGV-RNA. CD4+/CD8+ ratio (p=0.002) was the only variable included in the best model for HGV-RNA disappearance. INTERPRETATION AND CONCLUSIONS: A more accurate estimation of the prevalence of HGV infection can be achieved with the determination of both HGV RNA and anti-E2. Anti-E2 response can be undetectable or transitory after disappearance of HGV-RNA, giving therefore rise to the possibility of underestimating HGV prevalence with currently diagnostic methods. In HIV-positive patients, cellular immune function seems to be involved in the resolution of HGV infection, following the significant correlation found between clearance of HGV-RNA and CD4+/CD8+ lymphocyte populations.

Adolescent↗

PubMed1998

Effect of recombinant human erythropoietin treatment on circulating reticulated platelets in uremic patients: association with early improvement in platelet function.

Recombinant human erythropoietin improves platelet function in uremia through the correction of anemia, but this effect can be seen also before the hematocrit rise. We studied 12 hemodialyzed patients (seven men, five women) who received recombinant human erythropoietin (40 IU kg(-1)i.v., three times weekly) and were evaluated before treatment and after three doses; 24 control subjects were used. Platelet aggregation induced by adenosine 5'-diphosphate (ADP), epinephrine, collagen, arachidonic acid, and ristocetin, and reticulated platelets determined by flow cytometry after staining with thiazole orange were measured. Platelet aggregation induced by all the agonists were impaired in uremic patients (P < 0.01), but ADP and ristocetin-induced aggregations improved after treatment (P < 0.01). Hemodialyzed patients had less reticulated platelets than controls (P < 0.01). Reticulated platelets increased after three doses of treatment (P < 0.01). In conclusion, improvement of platelet function at early stages of recombinant human erythropoietin treatment may be attributed to the increase in young platelets detected as reticulated platelets.

Adenosine Diphosphate↗

PubMed1998

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.

Adult↗

PubMed1998

Antiphospholipid antibodies and the outcome of pregnancy after the first in-vitro fertilization and embryo transfer cycle.

Increased antiphospholipid antibody prevalence has been demonstrated by a number of recent studies in in-vitro fertilization (IVF) patients but the potential effects of antiphospholipid antibodies on the different components of the reproductive process and the consideration of whether to test IVF patients for antiphospholipid antibodies are controversial. The present study was undertaken to investigate the possible association between the presence of circulating antiphospholipid antibodies (namely the lupus anticoagulant and anticardiolipin antibodies), among a series of 21 consecutive IVF patients having a clinical spontaneous abortion after their first embryo transfer. As a control group (n=42), the nearest IVF cycle resulting in an ongoing pregnancy before and after each miscarried IVF cycle (i.e. the closest cycles in temporal relationship to the index cycle) was used. One patient (4.8%) in the study group and two women (4.8%) among controls were seropositive for antiphospholipid antibodies. These low and similar seropositivity rates found in the two groups studied lead us to conclude that antiphospholipid antibodies testing in IVF patients should be considered only in those women having repeated failures of implantation/clinical abortion after embryo transfer but not in an infertile general population reaching an IVF programme.

Abortion, Spontaneous↗

PubMed1998

Hepatitis G virus infection in primary Sjögren's syndrome: analysis in a series of 100 patients.

OBJECTIVE: To determine the prevalence and clinical significance of hepatitis G virus (HGV) infection in a large cohort of patients with primary Sjögren's syndrome (SS). PATIENTS AND METHODS: The study included 100 consecutive patients (92 female and eight male), with a mean age of 62 years (range 31-80) that were prospectively visited in our unit. All patients fulfilled the European Community criteria for SS and underwent a complete history, physical examination, as well as biochemical and immunological evaluation for liver disease. Two hundred volunteer blood donors were also studied. The presence of HGV-RNA was investigated in the serum of all patients and donors. Additionally, HBsAg and antibodies to hepatitis C virus were determined. RESULTS: Four patients (4%) and six volunteer blood donors (3%) presented HGV-RNA sequences in serum. HGV infection was associated with biochemical signs of liver involvement in two (50%) patients. When compared with primary SS patients without HGV infection, no significant differences were found in terms of clinical or immunological features. HCV coinfection occurs in one (25%) of the four patients with HGV infection. CONCLUSION: The prevalence of HGV infection in patients with primary SS is low in the geographical area of the study and HCV coinfection is very uncommon. HGV infection alone does not seen to be an important cause of chronic liver injury in the patients with primary SS in this area.

Adult↗

PubMed1997

Differential effect of a low-molecular-weight heparin (dalteparin) and unfractionated heparin on platelet interaction with the subendothelium under flow conditions.

Effects of heparins on platelet function are controversial, but perfusion studies, that simulate physiological conditions, might help to explain their clinical behaviour. We used a perfusion system to test the effect unfractionated heparin and a low-molecular-weight heparin (dalteparin, Fragmin) on platelet adhesion promoted by a damaged vascular surface. Normal blood samples containing increasing concentrations of unfractionated heparin and dalteparin were perfused through annular chambers containing enzymatically denuded rabbit aorta segments (5 min at 800 sec-1). Segments were evaluated morphometrically measuring the total surface covered by platelets and by large aggregates (thrombi). Unfractionated heparin inhibited platelet interaction with subendothelium in a lesser extent than dalteparin in both covered surface and thrombi (p < 0.01). At heparin doses that caused maximal inhibition covered surface was 10.0% +/- 3.1% with dalteparin and 18.3% +/- 4.2% with unfractionated heparin, and thrombi were 5.6% +/- 3.2% and 12.3% +/- 3.0%, respectively. These results may collaborate to explain some differences observed in the clinical results obtained with unfractionated heparin and with dalteparin.

Animals↗

PubMed1997

Antibodies to thromboplastin in systemic lupus erythematosus: isotype distribution and clinical significance in a series of 92 patients.

We determined the prevalence and relationship with clinical manifestations of antibodies to thromboplastin (aTP) in 92 patients with systemic lupus erythematosus (SLE). Thirty-two (35%) patients had aTP: 13 (14%) were positive for IgG aTP, 13 (14%) for IgM aTP, and 6 (7%) for both. Patients with aTP had an increased incidence of thrombosis (p = 0.01), thrombocytopenia (p < 0.001), hemolytic anemia (p < 0.001), and fetal losses (p = 0.03). When the IgG and IgM aTP isotypes were analysed separately, the IgG aTP were found to be associated with thrombosis (p < 0.001), thrombocytopenia (p < 0.001), and fetal losses (p = 0.02). The IgM aTP were associated with hemolytic anemia (p < 0.001). A correlation was found between the titers of aTP and those of anticardiolipin antibodies, in both IgG (p < 0.01, r = 0.6) and IgM (p < 0.01, r = 0.64) isotypes, and between the titers of IgG aTP and the diluted Russell's viper venom time used to detect the lupus anticoagulant (p < 0.001, r = 0.42). This test is a reliable, reproducible and sensitive assay for the detection of antiphospholipid antibodies, specially in those patients under anticoagulant therapy.

Adolescent↗

PubMed1997

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.

Adolescent↗

PubMed1997

In vitro evaluation of the hemostatic effectiveness of non viable platelet preparations: studies with frozen-thawed, sonicated or lyophilized platelets.

OBJECTIVES: Because of the limited life span of platelets in regular storage systems, we were interested in investigating the effects on hemostasis of nonliving platelet derivatives. METHODS: We evaluated the effects of different platelet preparations on primary hemostasis in a well-established perfusion model. Studies were carried out with blood anticoagulated with low molecular weight heparin. Similar amounts of frozen-thawed, sonicated or lyophilized platelets were added to normal blood or to blood which had been experimentally depleted of platelets. Platelet interaction with the subendothelium and fibrin deposition were morphometrically evaluated. RESULTS: Addition of nonviable platelet preparations to thrombocytopenic blood always promoted a statistically significant increase in the deposition of fibrin on the subendothelium, but only lyophilized platelets retained some ability to interact with the subendothelium. Flow cytometry studies demonstrated the presence of GPIb, GPIIIa and P-selectin on lyophilized platelets. CONCLUSIONS: Preparations containing nonviable platelets may still retain some hemostatic properties.

Animals↗

PubMed1997

Hemostasis in patients with severe von Willebrand disease improves after normal platelet transfusion and normalizes with further correction of the plasma defect.

BACKGROUND: A defective hemostatic effect of plasma concentrate infusion in patients with severe von Willebrand disease (vWD) has been ascribed to the absence of platelet von Willebrand factor (vWF) STUDY DESIGN AND METHODS: The role of platelet vWF in hemostasis of severe vWD was investigated. A plateletpheresis unit (4-5 x 10(11) platelets) from a normal compatible donor was transfused before any cryoprecipitate infusion to three type 3 vWD patients and to one patient with severe type 1 vWD with low levels of platelet vWF who required replacement therapy for bleeding episodes. Autologous platelets were transfused to one of the patients with type 3 vWD. RESULTS: Partial corrections of bleeding times (14-17 min vs. baseline >30 min) were observed in all patients after the transfusion of normal platelets. During cryoprecipitate infusion, bleeding times were normalized (<6 min), and bleeding episodes stopped when plasma levels of vWF activity ranged from 14 to 18 U per dL. Platelet interactions with the subendothelium increased in parallel with the correction of bleeding times. These results indicate that if approximately 20 percent of the total number of platelets have normal vWF antigen and if plasma vWF levels are at least 14 U per dL, then bleeding times will normalize and mucosal hemorrhages will stop. Transfusion of autologous platelets in one patient with type 3 vWD did not modify bleeding times or platelet adhesion on the subendothelium. CONCLUSION: The hemostatic effect of normal platelets in type 3 vWD seems to be related to the platelet vWF in the transfused platelets.

Bleeding Time↗

PubMed1997

First-trimester repeated abortion is not associated with activated protein C resistance.

The present study was undertaken to investigate the possible association between activated protein C resistance and first-trimester repeated abortion. Fifty-five consecutive patients with unexplained first-trimester repeated abortion and 50 healthy control women having at least one child but no previous abortion were included. Activated protein C resistance was measured in all subjects and factor V Leiden genotype testing was performed in those individuals with phenotypic activated protein C resistance. One patient with first-trimester repeated abortion and one control subject had phenotypic activated protein C resistance. Genotype analysis confirmed that both subjects were heterozygous for factor V Leiden. Our results indicate that first-trimester repeated abortion is not associated with activated protein C resistance. Factor V Leiden screening in first-trimester repeated abortion is not warranted.

Abortion, Habitual↗