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Study Question: Are there neurobiological changes induced by endometriosis?, Summary Answer: Women with endometriosis demonstrate specific neurobiological changes distinct from those in patients with chronic pelvic pain (CPP) in the absence of endometriosis., What Is Known Already: Endometriosis is a chronic disease affecting women of reproductive age that presents with pain and infertility often accompanied by comorbid mental disorders. Only one study with a number of limitations has investigated changes in gray matter volumes and functional connectivity in a small group of patients with endometriosis., Study Design, Size, Duration: This prospective study recruited 53 women undergoing a laparoscopy due to suspicion of symptomatic endometriosis and 25 healthy, pain-free women. Clinical and psychological characteristics, thermal pain perception, and voxel- and surface-based morphology were assessed in all study participants. Thereafter, the patients underwent a laparoscopy, where endometriosis was either histologically confirmed and removed, or ruled out. Correspondingly, patients were assigned into the group with endometriosis (n = 27) or with endometriosis-independent CPP (n = 26) and compared to the pain-free controls., Participants/materials, Setting, Methods: The study groups were generally representative for the population of women with endometriosis. Sociodemographic, medical, clinical, and psychological characteristics were collected using various questionnaires and a structured clinical interview. Thermal pain perception and voxel- and surface-based morphometry were assessed using thermode and MRI, respectively., Main Results and the Role of Chance: Despite comparable pain intensity and burden of mental disorders, both patient groups demonstrated distinct neurobiological patterns. Women with endometriosis exhibited increased gray matter volume (GMV) in the left cerebellum, lingual gyrus and calcarine gyrus, compared to those with endometriosis-independent CPP. Patients with CPP had decreased GMV in the right cerebellum as compared to controls. Dysmenorrhoea severity correlated positively with GMV in the left inferior parietal lobule, whereas depressive symptoms were associated with decreased GMV in the right superior medial gyrus across patient groups. Dyspareunia correlated negatively with cortical thickness in the left inferior temporal gyrus and left middle temporal gyrus., Limitations, Reasons for Caution: The study groups differed in a few baseline-characteristics, including educational levels, smoking and BMI. While measuring pain perception thresholds, we did not attempt to mimic CPP by placement of the thermode on the abdominal wall., Wider Implications of the Findings: Changes in gray matter volume associated with endometriosis differ from those observed in women with endometriosis-independent CPP. Our results underline an involvement of the cerebellum in pain perception and the pathogenesis of pain associated with endometriosis., Study Funding/competing Interest(s): This work was funded by the START Program of the Faculty of Medicine, RWTH Aachen, Germany, and supported by the International Research Training Group (IRTG 2150) of the German Research Foundation (DFG)-269953372/GRK2150, Germany. S.T. was supported by postdoctoral fellowship of the Faculty of Medicine, RWTH Aachen, Germany. There are no conflicts of interest., Trial Registration Number: DRKS00021236., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

TFF3 is a typical secretory poplypeptide of mucous epithelia belonging to the trefoil factor family (TFF) of lectins. In the intestine, respiratory tract, and saliva, TFF3 mainly exists as a high-molecular-mass complex with IgG Fc binding protein (FCGBP), which is indicative of a role in mucosal innate immunity. For the first time, we identified different forms of TFF3 in the endocervix, i.e., monomeric and homodimeric TFF3, as well as a high-molecular-mass TFF3-FCGBP complex; the latter also exists in a hardly soluble form. Immunohistochemistry co-localized TFF3 and FCGBP. Expression analyses of endocervical and post-menopausal vaginal specimens revealed a lack of mucin and TFF3 transcripts in the vaginal specimens. In contrast, genes encoding other typical components of the innate immune defense were expressed in both the endocervix and vagina. Of note, FCGBP is possibly fucosylated. Endocervical specimens from transgender individuals after hormonal therapy showed diminished expression, particularly of FCGBP. Furthermore, mucus swabs from the endocervix and vagina were analyzed concerning TFF3, FCGBP, and lysozyme. It was the aim of this study to illuminate several aspects of the cervico-vaginal innate immune barrier, which is clinically relevant as bacterial and viral infections are also linked to infertility, pre-term birth and cervical cancer.

Endometriosis is a chronic pain disorder that affects young women, impairing their physical, mental and social well-being. Apart from personal suffering, it imposes a significant economic burden on the healthcare system. We analyzed studies reporting comorbid mental disorders in endometriosis based on the ICD/DSM criteria, discussing them in the context of available neuroimaging studies. We postulate that at least one-third of endometriosis patients suffer from mental disorders (mostly depression or anxiety) and require psychiatric or psychotherapeutic support. According to three neuroimaging studies involving patients with endometriosis, brain regions related not only to pain processing but also to emotion, cognition, self-regulation and reward likely constitute the so-called "endometriosis brain". It is not clear, however, whether the neurobiological changes seen in these patients are caused by chronic pain, mental comorbidities or endometriosis itself. Given the paucity of high-quality data on mental comorbidities and neurobiological correlates in endometriosis, further research is needed., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Hormonal contraception is a well-known risk factor for venous thromboembolism (VTE). APC resistance and impaired functions of protein S and TFPI are thought to play an important role in the pathogenesis of hormone-related VTE. It is unknown, whether women, who develop VTE during hormonal contraception possess a vulnerability in these pathways, making them susceptible to thrombosis., Materials and Methods: Plasma samples were obtained from 57 premenopausal women in average 15.3 years after hormone-associated VTE and from 31 healthy controls. Thrombin generation at high tissue factor (TF) in the absence and in the presence of activated protein C (APC) and at low TF without and with inhibiting anti-protein S- and anti-TFPI-antibodies was measured via calibrated automated thrombography., Results: Women with previous hormone-related thrombosis had higher thrombin generation at low TF, higher APC resistance, protein S- and TFPI ratios, differences: 219.9 nM IIa.min (95%CI:90.4 to 349.3); 1.88 (95%CI:0.71 to 3.05); 0.13 (95%CI:0.01 to 0.26) and 0.19 (95%CI:0.08 to 0.30), respectively. Thrombin generation at high TF without APC did not differ between the groups. Smoking decreased thrombin generation at low TF by -222.6 nM IIa.min (95%CI: -381.1 to -64.1), the APC sensitivity ratio by -2.20 (95%CI: -3.63 to -0.77) and the TFPI ratio by -0.16 (95%CI: -0.29 to -0.03), but did not influence thrombin generation at high TF., Discussion: We demonstrated impairment of the protein S/TFPI system and increased APC resistance in women with previous hormone-induced VTE. Smoking decreased thrombin generation at assay conditions, dependent on the function of the TFPI system., (Copyright © 2021. Published by Elsevier Ltd.)

Introduction: Venous thrombosis is the leading cause of pregnancy-related maternal morbidity and mortality. The thrombosis risk is increased by caesarean section and blood loss, though underlying mechanisms of these prothrombotic changes remain unknown., Materials and Methods: This prospective study recruited 50 pregnant women at term undergoing elective caesarean section at University Hospital Magdeburg, Germany. Blood loss during surgery was correlated with the changes in total protein S, full length TFPI (TFPI fl ), prothrombin, the endogenous thrombin potential (ETP) and resistance to activated protein C (APCsr) determined via calibrated automated thrombography., Results: Mean blood loss was 506 ml (95%CI: 456 to 557 ml). Total protein S was 0.63 (95%CI: 0.60 to 0.67) U/ml preoperatively, decreased by 14.8% after caesarean section and almost normalised five days later. TFPI fl was 0.47 (95%CI: 0.41 to 0.53) U/ml before, remained unchanged immediately after and increased by 11.5% five days after surgery. Prothormbin was 1.10 (95%CI: 1.03 to 1.16) U/ml preoperatively, reduced by 10.4% immediately after and increased again five days after caesarean section, exceeding the preoperative values by 4.4% (-0.7 to 9.6). The ETP decreased by 3.9%, whereas the APCsr increased by 37.0% immediately after caesarean section. The changes in total protein S, prothrombin, thrombin generation and APC resistance showed a trend to be more pronounced in the subgroups with higher blood loss., Discussion: Moderate blood loss during caesarean section hardly reduces thrombin generation but aggravates pregnancy-induced APC resistance and combined deficiency of TFPI and protein S, which can account for the increased thrombosis risk in early puerperium., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Introduction: Elderly breast cancer patients aged ≥75 years are underrepresented in most studies. Therefore, data on cancer characteristics, adjuvant treatment and survival in elderly patients are missing., Patients and Methods: In this retrospective study, we compared tumor characteristics and adjuvant therapy in 973 women with invasive, non-metastasized breast cancer aged ≥75 years with 3377 younger postmenopausal patients (50-74 years old). Time dynamics of tumor characteristics were investigated, comparing two observation periods between the years 2000-2004 versus 2005-2008., Results: Compared to younger women, older patients were more often treated with mastectomy and less likely to receive adjuvant treatment. Although the overall survival rate increased over the observation period in both age groups, the older study group was characterized by shorter disease-free survival. Additionally, we observed an increase in about 1.65 years in the age at diagnosis as well as an increasing rate of breast-conserving surgery and sentinel lymph node biopsy for the whole study population between 2000 and 2008. Furthermore, we found a reduction in the proportion of estrogen receptor-positive tumors in the younger women and a decrease in G3-tumors in both age groups over the study time., Conclusion: The older group's reduced disease-free survival could be explained by the tumor characteristics and differences in the adjuvant treatment. Remarkably, elderly women are more likely to be overtreated surgically while being undertreated in terms of adjuvant therapy.

Problem: Thrombophilia is associated with pregnancy complications. Treatment with low molecular weight heparin (LMWH) improves pregnancy outcome, but the underlying mechanisms are not clear., Methods of Study: We analyzed Treg frequency in blood from thrombophilic pregnancies treated with LMWH (n = 32) or untreated (n = 33) and from healthy pregnancies (n = 39) at all trimesters. Additionally, we treated pregnant wild-type, heterozygous and homozygous factor-V-Leiden (FVL) mice with LMWH or PBS and determined Treg frequency, pro-/anti-inflammatory cytokine levels and Caspase-3-activity in placenta and decidua., Results: Treg frequencies were increased in second and third trimester in LMWH-treated thrombophilic pregnancies compared to controls. Treg levels were comparable to those of normal pregnancies. Homozygous FVL mice had decreased decidual Tregs compared to wild-type mice. LMWH treatment normalized Tregs and was associated with increased decidual IL-10 mRNA. LMWH diminished Caspase-3-activity in mice of all genotypes., Conclusion: We demonstrated anti-apoptotic and anti-inflammatory effects of LMWH in pregnant FVL mice. LMWH increased Treg levels in mice and humans, which suggests benefits of LMWH treatment for thrombophilic women during pregnancy., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Thrombophilia is a prothrombotic state that can be caused by genetic disorders, such as the factor-V-Leiden or prothrombin mutation, as well as by acquired changes like oestrogen-induced APC resistance and the antiphospholipid syndrome. Pregnancy induces multiple procoagulant changes in the haemostatic system, increasing the risk of venous thromboembolism in women with a thrombophilia even further. Additionally, thrombophilias are suggested to be associated with a number of pregnancy complications such as recurrent miscarriage, stillbirth, preeclampsia and HELLP syndrome. Increased local activation of coagulation may directly influence trophoblast expansion and invasion, causing thereby an impaired trophoblast development and insufficient widening of spiral arteries in the first trimenon, which results in placenta-mediated pregnancy complications like preeclampsia or HELLP syndrome. Besides, macro- and microthrombosis in the vessels of placental stemm villi and spiral arteries may lead to multiple infarctions with release of necrotic trophoblast fragments and inflammatory cytokines playing an important role in the pathogenesis of recurrent pregnancy loss and stillbirth. For women with a known thrombophilia it is recommended to carry out either only postpartal or combined ante- and postpartal thrombosis prophylaxis with low-molecular weight heparins (LMWH) depending on the individual risk stratification. The effectiveness of the LMWH administration for prevention of thrombophilia-induced pregnancy complications and improvement of the pregnancy outcome is currently a matter of debate. Furthermore, an additional application of acetyIsalicylic acid (ASA) should be considered in the management of women with the antiphospholipid antibody syndrome. In the current article we present the case of a 28-year-old woman with the heterozygous prothrombin mutation, HELLP syndrome, a late miscarriage and a stillbirth in the anamnesis, who delivered 3 healthy babies under antenatal LMWH prophylaxis combined with intensive interdisciplinary prenatal care., (© Georg Thieme Verlag KG Stuttgart · New York.)

Introduction: Oral contraceptives (OC) increase the risk of venous thromboembolism that depends on the OC formulation and could at least partially be explained by impaired function of the protein C-system (APC resistance) and the tissue factor pathway inhibitor (TFPI)-system. There is limited information available on the effects of OC, containing a newer progestogen- drospirenone (DRSP-OC) on these two major anticoagulant pathways, thrombin generation, reflecting the overall state of coagulation, and other coagulation parameters., Methods: In a study population consisting of 14 healthy women (age 21-33 years) we investigated the effect of the menstrual cycle and subsequent use of DRSP-OC on APC resistance, the function of the TFPI-system, thrombin generation and on their major determinants, i.e. prothrombin, antithrombin, FV, FX, FVIII, protein C, protein S(total and free) and TFPI(full-length and free)., Results: All studied parameters remained unchanged during the menstrual cycle. During DRSP-OC use we observed a significant increase in APC resistance (~2.4-fold), thrombin generation measured at low (~2.2-fold) and high tissue factor concentrations (~1.4-fold), plasma concentrations of prothrombin (19%), FX (31%), FVIII (17%) and protein C (43%). DRSP-OC use impaired the function of the TFPI-system and decreased plasma levels of antithrombin (-6%), FV (-22%), protein Stotal (-21%), protein Sfree (-20%), TFPIfull-length (-36%) and TFPIfree (-46%)., Conclusions: DRSP-OC caused procoagulant changes in all studied haemostatic parameters. The impairment of the protein C- and TFPI-systems was more pronounced than the impairment of the coagulation pathways and can at least partially account for the increased risk of venous thromboembolism in users of DRSP-OC., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Obesity is a known risk factor for venous and arterial thrombosis but the mechanisms are still unclear. In women, obesity is correlated with low-grade inflammation and recent data show that BMI is positively associated with thrombin generation. We explored the correlations between obesity, inflammation and thrombin generation in women with increased thrombotic risk by looking at a cohort of women with prior venous thrombosis. One hundred and fifty-six women age 18-65 years were enrolled at diagnosis of first venous thromboembolism (VTE). Plasma samples were obtained at least 3 weeks after cessation of anticoagulant treatment. Thrombin generation was determined with the calibrated automated thrombography (CAT) assay and the Innovance ETP assay. Thrombin generation started later but was more pronounced with higher endogenous thrombin generation potential (ETP) determined with CAT in patients with obesity. The Innovance ETP assay showed results consistent with CAT. Furthermore, patients with obesity had significantly higher levels of fibrinogen, C-reactive protein and plasminogen activator inhibitor-I (PAI-I) than patients without obesity. Increased levels of fibrinogen were the main determinant of the prolonged lag-time in patients with obesity whereas higher levels of prothrombin could account for the difference in the ETP between the groups. We found an association between BMI and ETP values using two different methods to measure thrombin generation. Obesity correlated with increased thrombin generation in women with VTE and the main determinants of this hypercoagulable state were increased levels of fibrinogen and prothrombin. This shows a possible link between obesity, low-grade inflammation and increased thrombin generation in women at increased risk for future thrombosis.

Pregnancy increases the risk of venous thromboembolism. Particularly in early pregnancy, the thrombosis risk can be attributed to the changes in coagulation. Elevated thrombin generation and resistance to activated protein C (APC) are likely to contribute to the increased thrombosis risk during pregnancy. We studied changes and the determinants of thrombin generation and APC resistance in the first 16 weeks of gestation in women with history of preeclampsia. Additionally, we investigated the influence of pregnancy-induced haemodilution on the coagulation system. We measured thrombin generation, APC resistance and plasma levels of prothrombin, factor V, factor X, protein S and tissue factor pathway inhibitor (TFPI) in 30 non-pregnant and 21 pregnant women at 8, 12 and 16 weeks of gestation. All participants shared a history of a hypertensive complication in the preceding pregnancy. Thrombin generation and APC resistance were higher at eight weeks of pregnancy than in the non-pregnant state, and progressively increased between eight and 16 weeks of gestation. Changes in the TFPI and protein S levels accounted for ~70% of pregnancy-induced APC resistance. Interestingly, a significant correlation (slope 2.23; 95%CI: 1.56 to 2.91; r= 0.58) was observed between protein Stotal or protein Sfree levels and haematocrit. In conclusion, pregnancy induces a decrease of TFPIfree and protein Sfree levels that attenuates the function of the TFPI and protein C systems and results in elevated thrombin generation and increased APC resistance. Besides, our data suggest that pregnancy-dependent haemodilution may contribute to the decreased peripheral protein S levels.

Identification of patients at high risk of recurrence after a first event of venous thromboembolism (VTE) remains difficult. Resistance to activated protein C (APC) is a known risk factor for VTE, but data on the risk of recurrence is controversial. We wanted to investigate whether APC resistance in the absence of factor V Leiden, determined with global coagulation test such as the thrombin generation assay, could be used as a marker for increased risk of recurrent VTE among women 18-65 years old after a first event of VTE. In a cohort of 243 women with a first event of VTE, plasma was collected after discontinuation of anticoagulant treatment and the patients were followed up for 46 months (median). Thrombin generation was measured via calibrated automated thrombography, at 1 pM and 10 pM of tissue factor (TF). In women without factor V Leiden (n=117), samples were analysed in the absence and in the presence of APC. Increase in ETP (endogenous thrombin potential) and peak height analysed in the presence of APC correlated significantly with higher risk of recurrence. At 1 pM, peak height correlated with increased risk of recurrence. In conclusion, high thrombin generation in the presence of APC, in women after a first event of VTE is indicative for an increased risk of a recurrence. We also found that thrombin generation at low TF (1 pM) is correlated with the risk of recurrence. Our data suggest that APC resistance in the absence of factor V Leiden is a risk factor for recurrent VTE.

The use of oral contraceptives (OC) is a well established risk factor for venous thrombosis. It has been known for many years that almost all haemostatic parameters i.e. plasma levels of coagulation factors, anticoagulant proteins and proteins involved in the fibrinolytic pathway change during OC use. The discovery of several risk factors of venous thrombosis in the 1990s shed new light on the association between the effects of OC on the haemostatic system and the increased risk of venous thrombosis. In this review, we summarize the current knowledge on the effects of different kinds of hormonal contraceptives (OC, transdermal contraceptives, vaginal ring and levonorgestrel-releasing intrauterine device) on haemostatic variables and the relationship between the changes of these variables and the risk of venous thrombosis., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Protein S (PS) is an important natural anticoagulant with potentially multiple biologic functions. To investigate further the role of PS in vivo, we generated Pros(+/-) heterozygous mice. In the null (-) allele, the Pros exons 3 to 7 have been excised through conditional gene targeting. Pros(+/-) mice did not present any signs of spontaneous thrombosis and had reduced PS plasma levels and activated protein C cofactor activity in plasma coagulation and thrombin generation assays. Tissue factor pathway inhibitor cofactor activity of PS could not be demonstrated. Heterozygous Pros(+/-) mice exhibited a notable thrombotic phenotype in vivo when challenged in a tissue factor-induced thromboembolism model. No viable Pros(-/-) mice were obtained through mating of Pros(+/-) parents. Most E17.5 Pros(-/-) embryos were found dead with severe intracranial hemorrhages and most likely presented consumptive coagulopathy, as demonstrated by intravascular and interstitial fibrin deposition and an increased number of megakaryocytes in the liver, suggesting peripheral thrombocytopenia. A few E17.5 Pros(-/-) embryos had less severe phenotype, indicating that life-threatening manifestations might occur between E17.5 and the full term. Thus, similar to human phenotypes, mild heterozygous PS deficiency in mice was associated with a thrombotic phenotype, whereas total homozygous deficiency in PS was incompatible with life.

Exogenously administered estrogens and progestogens as during combined oral contraceptive use increase the risk of venous thrombosis. The thrombin generation-based APC resistance assay is a global coagulation test that enables quantification of the net prothrombotic effect of combined oral contraceptives and that predicts the risk of thrombosis. The thrombotic risk of the levonorgestrel-releasing intrauterine system is unknown. It was the objective of this study to evaluate the thrombotic risk by comparing the APC resistance before and after insertion of a levonorgestrel-releasing or a copper-containing intrauterine device. We measured normalized APC-sensitivity ratios (nAPCsr) before and three months after insertion of the levonorgestrel-intrauterine system in 56 women and the copper-intrauterine device in 18 women. In women without hormonal contraceptive use or a pregnancy in the three months before collection of the baseline samples, nAPCsr were lower three months after insertion of the levonorgestrel-intrauterine system than at baseline (difference -0.29; 95% CI -0.04 to -0.53) and hardly changed after insertion of the copper-intrauterine device (difference -0.11; 95% CI -1.03 to 0.82). In women who switched from a combined oral contraceptive to the levonorgestrel-system the difference was more pronounced (-1.48; 95% CI -0.85 to -2.11). In this study we observed that the levonorgestrel-intrauterine system decreases the resistance to APC which indicates that the levonorgestrel-intrauterine system does not have a prothrombotic effect.

Background: Pregnancy, oral contraceptive (OC)use and hormone replacement therapy (HRT) are established risk factors for venous thrombosis. Acquired resistance to activated protein C (APC) has been proposed to contribute to the increased thrombosis risk. Mouse models are often used for preclinical testing of newly developed hormone preparations. However, it is not known whether hormone-induced APC resistance is also observed in laboratory animals., Objectives: To investigate whether hormonal changes modulate APC resistance in mice, we used pregnant mice as a model of hormone-induced APC resistance. The effect of pregnancy on APC resistance was studied in wild-type and factor (F)V Leiden mice., Methods: APC resistance was determined in mouse plasma using a thrombin generation-based APC resistance test. APC resistance determinants,i.e. prothrombin, FV, FX, antithrombin and protein S levels,and of tissue factor pathway inhibitor (TFPI) activity were evaluated in plasma from non-pregnant and pregnant mice., Results: In contrast to humans, pregnancy induced a decrease in APC resistance in wild-type and in FV Leiden mice.Pregnant mice had higher levels of prothrombin, FV, FX,protein S and TFPI activity as compared with non-pregnant mice., Conclusions: Pregnancy causes a decrease in APC resistance in mice, which can be explained by the elevation of protein S levels and increased TFPI activity in plasma. Our findings show species specificity in the effects of pregnancy on the major determinants of the protein C system and suggest that protein S and TFPI play an important role in the development of pregnancy-induced APC resistance in humans.

Protein S is a vitamin K-dependent protein that acts as a cofactor of the anticoagulant protein APC. However, protein S also exhibits anticoagulant activity in the absence of APC. Thrombin generation experiments in normal plasma and in plasma deficient in tissue factor pathway inhibitor (TFPI) and/or protein S demonstrated that protein S stimulates the inhibition of TF by TFPI. Kinetic analysis in model systems containing purified proteins showed that protein S enhances the formation of the binary FXa:TFPI complex by reducing the Ki of TFPI from approximately 4 nM to approximately 0.5 nM. Enhancement of inhibitory activity of TFPI by protein S is only observed with full-length TFPI and in the presence of a negatively charged phospholipid surface. The Ki decrease brings the TFPI concentration necessary for FXa:TFPI complex formation within range of the plasma TFPI concentration which increases FXa:TFPI complex formation and accelerates feedback inhibition of the TF pathway by enhancing the formation of the quaternary TFPI:FXa:TF:FVIIa complex. Thus, protein S is not only a cofactor of APC, but also of TFPI. A reduced TFPI cofactor activity may contribute to the increased risk of venous thrombosis in protein-S deficient individuals. Using calibrated automated thrombography we have developed two assays that enable quantification of the functional activity of the TFPI/protein S system in plasma. These assays show that the activity of the TFPI/protein S system is greatly impaired in oral contraceptive users.

In a study population consisting of healthy men (n = 8), women not using oral contraceptives (OC) (n = 28) and women using different kinds of OC (n = 187) we used calibrated automated thrombography (CAT) in the absence and presence of added activated protein C (APC) to compare parameters that can be obtained from thrombin generation curves, i.e. lag time, time to peak, peak height and endogenous thrombin potential (ETP). Both with and without APC, plasmas of OC users exhibited the shortest lag time and time to peak, and the highest peak height and ETP. In the absence of APC none of these parameters differed between users of OC containing different progestogens. In contrast, in the presence of APC shorter lag times and time to peak, and higher peak height and ETP were observed in plasma of users of gestodene-, desogestrel-, drospirenone- and cyproterone acetate-containing OC than in plasma of users of levonorgestrel- containing OC. The ETP determined in the absence of APC (ETP(-APC)) had no predictive value for the APCsr (r = 0.11; slope 0.9 x 10(-3); 95% CI: -0.1 x 10(-3) to 2.0 x 10(-3)) whereas the ETP measured in the presence of APC (ETP+APC) showed an excellent correlation with the APCsr (r = 0.95; slope 6.6 x 10(-3); 95% CI: 6.3 x 10(-3) to 6.9 x 10(-3)) indicating that the APCsr is entirely determined by the ETP+APC. In conclusion, OC use increases thrombin generation, but differential effects of second and third generation OCs on the protein C system likely determine the differences in the risk of venous thrombosis between these kinds of OC.

Background: Mouse models have become increasingly important in thrombosis research. However, only a limited number of assays are available for assessment of the coagulation system in mouse plasma., Objectives: To quantify tissue factor-initiated thrombin generation in murine platelet-rich and platelet-free plasma and to develop a test for measurement of resistance to activated protein C (APC) in mouse plasma., Methods: Thrombin generation was monitored with calibrated automated thrombography (CAT) using a low-affinity fluorogenic substrate for thrombin., Results: To overcome the higher activity of coagulation inhibitors in mouse plasma as compared with human plasma, the reaction temperature was lowered to 33 degrees C and the assay was carried out at a 2-fold higher final plasma dilution (1:3) than commonly used for CAT in human plasma. This increased the endogenous thrombin potential (ETP) 4- to 5-fold and enabled reliable measurement of thrombin generation in both platelet-free and platelet-rich mouse plasma. For the APC resistance measurement, the reaction conditions were further optimized with respect to tissue factor, phospholipid, APC and CaCl(2) concentrations. The test was validated using plasma of mice with different genetic background with respect to the factor V Leiden mutation (FV Leiden). Mice homozygous for FV Leiden had higher APC sensitivity ratios (mean 5.46; 95% CI 4.88-6.03) than heterozygous FV Leiden mice (mean 4.21; 95% CI 3.53-4.89) and than wild-type mice (mean 2.71; 95%CI 2.15-3.27)., Conclusions: We have established reaction conditions for measurement of thrombin generation and APC resistance in mouse plasma. This assay enables evaluation of the coagulation system and the function of the protein C system in mouse models.