Only minor changes in thrombin generation of children and adolescents with type 1 diabetes mellitus - A case-control study.

BACKGROUND: Micro- and macrovascular diseases are frequent complications in patients with diabetes. Hypercoagulability may contribute to microvascular alterations. OBJECTIVE: In this study, we investigated whether type 1 diabetes in children is associated with a hypercoagulable state by performing a global function test of coagulation - the thrombin generation assay. SUBJECTS: 75 patients with type 1 diabetes aged between 2 and 19years were compared to an age-matched healthy control group. Diabetes patients were divided into high-dose and low-dose insulin cohorts with a cut-off at 0.8Ukg-1d-1. METHODS: Measurements were performed with platelet poor plasma using Calibrated Automated Thrombography and 1 pM or 5 pM tissue factor. Additionally, we quantified prothrombin fragments F1+2, thrombin-antithrombin complex, prothrombin, tissue factor pathway inhibitor, and antithrombin. RESULTS: Patients with type 1 diabetes exhibited a significantly shorter of lag time as well as decreased thrombin peak and endogenous thrombin potential compared to control subjects with 5 pM but not with 1 pM tissue factor. In high-dose insulin patients peak thrombin generation was higher and time to peak shorter than in low-dose patients. Thrombin-antithrombin complex was decreased in patients with type 1 diabetes, whereas prothrombin fragments F1+2 was comparable in both groups. Thrombin generation parameters did not correlate with parameters of metabolic control and the duration of diabetes. CONCLUSIONS: Taken together, we found only minor changes of thrombin generation in children and adolescents with type 1 diabetes which - in contrast to type 2 diabetes - do not argue for a hypercoagulable state.

Low endogenous thrombin potential in trained subjects.

INTRODUCTION: A paradox seems to exist: exercising leads to clotting activation in conventional clotting tests, but exercising persons have a low risk of thrombosis. In this study we tried to evaluate the effect of exercise performance status on in vitro plasma thrombin generation, which represents an overall function test of hemostasis. MATERIALS AND METHODS: We compared 56 trained subjects to 98 healthy age matched sedentary volunteers. Blood samples were analyzed for thrombin generation using calibrated automated thrombography. Microparticles were quantified using ELISA. Additionally prothrombin fragments 1 + 2, thrombin-antithrombin complex, tissue factor pathway inhibitor, antithrombin and prothrombin were measured. The group of the trained subjects performed an incremental cycle-ergometer exercise test after taking the blood sample. RESULTS: A significantly lower endogenous thrombin potential was observed in the group of the trained subjects compared to the sedentary individuals (p = 0.007). Microparticles (ELISA) were significantly lower in the trained subjects compared to the sedentary subjects (p = 0.001). Prothrombin fragments 1 + 2 (p < 0.001) and thrombin-antithrombin complex (p = 0.01) were significant higher in the trained subjects and antithrombin (p = 0.02) as well as prothrombin (p < 0.0001) were significantly lower in this group, whereas tissue factor pathway inhibitor values did not show significant differences. Both maximal and submaximal power output was significantly negatively related to endogenous thrombin potential (r = -0.43, r = -0.45) and thrombin peak (r = -0.44, r = -0.42). CONCLUSIONS: Trained subjects have a lower endogenous thrombin potential than sedentary subjects possibly explaining the lower incidence of thrombosis in this group despite a higher acute clotting activation during strenuous exercise.

The predictive value of immature granulocyte count and immature myeloid information in the diagnosis of neonatal sepsis.

BACKGROUND: To determine the predictive value of the immature granulocyte count and the immature myeloid information in neonatal early onset sepsis we examined 133 blood samples of patients admitted to our neonatal intensive care unit. METHODS: Measurements were performed using the Sysmex XE-2100, an automated hematological analyzer. Patients were divided into two groups: 1) symptomatic neonates with diagnosis of early onset sepsis; and 2) controls including asymptomatic neonates who were admitted because of prematurity, low birth weight, or delayed postnatal transition. RESULTS: The number of immature granulocytes and the immature myeloid information were significantly elevated in neonates with early onset sepsis compared to controls (median 280/µL vs. 50/µL, p=0.049 and 639/µL vs. 89/µL, p<0.0001, respectively). CONCLUSIONS: Automated determinations of immature granulocytes and immature myeloid information seem to be useful adjunctive methods in the diagnosis of neonatal early onset sepsis.

Thrombin generation before and after multicomponent blood collection.

BACKGROUND: Apheresis technology has made tremendous progress up to the development of automated blood component collection, which offers increased efficiency in donor blood use, but the concern about the contact of donor blood with artificial surfaces remains. Activation of the hemostatic system is a major issue in this context and is controversial. The aim of this study was to estimate the effect of apheresis on continuous thrombin generation (TG), representing a new tool to examine the overall function of the plasmatic clotting system. STUDY DESIGN AND METHODS: Twenty-six voluntary blood donors, fulfilling the law requirement for apheresis donation, participated in the study. Two units of platelets (6 x 10(11)) and 1 unit of red cells (250 mL; hematocrit level, 80%) were collected using two types of cell separators (Amicus, Fenwal, Inc.; and Trima Accel, Gambro BCT). Each donor underwent collection on both apheresis systems with at least 8 weeks in between. Samples of blood were collected before, immediately after, and 48 hours after apheresis. TG was measured using a slow fluorogenic substrate by means of calibrated automated thrombography (CAT). RESULTS: CAT data changed only slightly, and no significant changes were seen before, immediately after, and 48 hours after apheresis (p > 0.05). The variables did not differ significantly between the two different apheresis systems (p > 0.05). CONCLUSION: Using a CAT-based technique, no change in variables of continuous TG were observed, suggesting that multicomponent blood collection did not lead to severe alterations in the hemostatic system of the donors.

The respective and combined anticoagulant effects of recombinant human activated protein C, melagatran and heparins using CAT.

INTRODUCTION: Combinations of anticoagulants might be beneficial in some patients with sepsis, but most anticoagulants require specific clotting assays for monitoring. Thrombin generation assay, however, is a global function test of hemostasis. MATERIALS AND METHODS: We performed an in vitro investigation of the respective effects of recombinant human activated protein C (rhAPC) alone and in combination with either melagatran (a new direct thrombin inhibitor), unfractionated heparin (UH) or low molecular weight heparin (LMWH) in varying concentrations on the thrombin generation (TG) using the calibrated automated thrombography. RESULTS: RhAPC, UH, LMWH and melagatran dose-dependently prolonged the lag time and the time to peak, and significantly suppressed the endogenous thrombin potential (ETP). Combined application of rhAPC with either melagatran, UH or LMWH induced an additive prolongation of the lag time; this effect was more pronounced in a combination of rhAPC with UH or LMWH. CONCLUSION: In our in vitro study adding either melagatran, UH or LMWH augmented the capacity of rhAPC to suppress thrombin generation in human plasma. These findings suggest that patients with severe sepsis might benefit from a treatment with combinations of anticoagulant agents.

Anticoagulant action of melagatran: a comparison between neonates and adults using calibrated automated thrombography (CAT).

In the present study, we comparatively evaluated the anticoagulant efficacy of the new direct thrombin inhibitor melagatran in cord vs. adult plasma. In contrast to heparin, melagatran does not require antithrombin as a cofactor. Thus, anticoagulant treatment with melagatran is of special interest in neonatal patients, whose plasma is relatively deficient in antithrombin. We evaluated the anticoagulant action of increasing amounts of melagatran (0.1-2.0 micromol/l) in both cord and adult plasma by means of calibrated automated thrombography (CAT) with respect to the lag time until the onset of thrombin formation, time to thrombin peak maximum (TTP), endogenous thrombin potential (ETP), and thrombin peak height. Melagatran exhibited approximately the same ability to prolong lag times or TTPs in both cord and adult plasma. Similar concentrations (IC(50)) of melagatran were required to double the lag times (0.44+/-0.04 micromol/l vs. 0.52+/-0.05 micromol/l) or to double the TTPs (0.91+/-0.08 micromol/l vs. 1.06+/-0.09 micromol/l) in cord vs. adult plasma. Melagatran exhibited a higher ability to suppress ETPs or thrombin peak heights in cord vs. adult plasma. Markedly lower concentrations (IC(50)) of melagatran were required to suppress ETPs (0.27+/-0.03 micromol/l vs. 0.70+/-0.06 micromol/l) or thrombin peak heights by 50% (0.29+/-0.03 micromol/l vs. 0.53+/-0.04 micromol/l) in cord vs. adult plasma. We conclude that our results suggest a higher ability of melagatran to suppress thrombin formation in cord vs. adult plasma. Thus, lower amounts of melagatran might be required in neonates undergoing antithrombotic therapy.

Effects of melagatran on activated partial thromboplastin time and on ecarin clotting time in cord versus adult plasma.

Melagatran is the active form of the oral direct thrombin inhibitor ximelagatran. Melagatran does not require antithrombin as a cofactor. Its administration is therefore of special interest in neonatal patients, whose plasma is relatively deficient in antithrombin. We investigated the effects of increasing amounts of melagatran (0.05-1 micromol/l) on the activated partial thromboplastin time (APTT) and ecarin clotting time (ECT) in cord versus adult plasma. Both the APTT and ECT were dose-dependently prolonged in the presence of increasing amounts of melagatran. Furthermore, the ECT revealed a higher susceptibility of cord plasma to addition of melagatran than adult plasma. Whereas similar amounts of melagatran were required in cord and adult plasma samples to double the APTT (IC(50), 0.47 vs 0.46 micromol/l), significantly less melagatran was required in cord versus adult plasma to double the ECT (IC(50), 0.26 vs 0.56 micromol/l). Based on APTT measurements, similar plasma levels of melagatran might be required in neonates and in adults to treat thromboembolic complications. The APTT, however, is relatively insensitive to plasma melagatran concentrations. When the sensitive indicator ECT is used, results suggest that lower amounts of melagatran might be required in neonates than in adults. This has to be scrutinized in future clinical studies.

Age-dependency of thrombin generation measured by means of calibrated automated thrombography (CAT).

Many coagulation parameters, such as PT or aPTT, show age-dependency. In this study we investigated if the generation of thrombin, possibly better reflecting overall haemostasis, shows an age-dependency. Thrombin generation was measured in platelet poor plasma of 121 children and 86 adults at different ages by means of calibrated automated thrombography (CAT). Correlation analysis shows that endogenous thrombin potential (ETP) (r = 0.702), lag time (r = -0.266), peak (r = 0.533) and time to peak (r = -0.214) are significantly correlated with age (p < 0.01). 'Younger' (age limit 35 years) and 'older' adults were compared with groups of children and adolescent aged between 0.5 and 6 years, 7 and 11 years and 12 to 17 years by means of the Mann-Whitney-U-Test. ETP values of all children and adolescents were significantly lower than those of adults. In the group of the youngest children, additionally shorter lag times and times to peak and lower peak levels differed significantly from those of adults. In the group of 7- to 11-year-old children, lag times were significantly longer than those of both groups of adults, while lower peaks and longer times to peak differed only from the group of the 'older' adults. In the group of the 12- to 17-year-olds, the values of ETP were lower than those of adults. In addition, both adult groups differed significantly in all studied parameters. Our results show an age-dependency of thrombin generation even beyond the juvenile period. If thrombin generation measurement is to be used as a routine method, age has to be considered. Assuming that thrombin potential is an indicator for the risk of thrombosis, our findings are in accordance with the observation of an increased incidence of thrombembolic disease with higher age.