A case series of LMWH use in pregnancy: Should trough anti-Xa levels guide dosing?

Introduction

Pregnancy is a thrombogenic state, increasing the risk for venous thromboembolism (VTE), and the risk of valve thrombosis amongst women with mechanical heart valves (MHV). While low molecular weight heparins (LMWH) are generally dosed based on weight (i.e., enoxaparin 1 mg/kg every 12 hours), data in pregnant women have shown that weight-based dosing does not consistently achieve target anti-Xa levels. In women with MHV, our practice includes titrating LMWH doses to target both trough and peak anti-Xa levels, while for those with VTE peak anti-Xa levels guide dosing.

Materials/Methods

This retrospective case series included pregnant women requiring LMWH treatment doses with at least 3 peak (+/− trough) anti-Xa levels. Our primary objective was to describe the actual LMWH dose required to achieve targeted anti-Xa levels relative to weight-based dosing in patients with MHV. Secondarily, we compared the same for VTE patients; compared actual dosing between those with MHV and VTE; and examined maternal and fetal outcomes.

Results/Conclusion

Women with MHV (N = 4) required greater than weight-based dosing of enoxaparin (1.35 mg/kg Q12H) to achieve targeted anti-Xa levels. Importantly, achieving target peak anti-Xa levels did not always ensure maintenance of minimum trough levels. VTE patients (N = 12) did not require more enoxaparin (0.96 mg/kg Q12H) than weight based dosing. MHV patients received more enoxaparin compared to VTE patients (P < 0.001). No bleeding or clotting complications were associated with LMWH administration. In pregnant women with MHV at high risk of thromboembolism, LMWH dosing guided by trough and peak anti-Xa levels should be considered.     

华蟾素对SD大鼠膀胱肿瘤的抑制作用

目的 研究华蟾素对SD大鼠膀胱肿瘤的治疗作用.方法 50只SD大鼠按随机分为对照组和实验组,实验组40只大鼠膀胱灌注N-甲基-N-亚硝基脲(N-methyl-N-nitrosourea,MUN),每3周1次,共4次;于第14周将实验组大鼠随机分为生理盐水组(膀胱灌注生理盐水)、丝裂霉素组(5 mkg)、低浓度华蟾素组(5 mg/kg)及高浓度华蟾素组(20 mg/kg),每周灌注1次,连续灌注5次,计算抑瘤率,TUNEL法检测肿瘤细胞的凋亡情况.结果 MNU膀胱灌注成功建立膀胱肿瘤动物模型,以膀胱肿瘤质量计算高浓度华蟾素组的抑瘤率为76.7％,高浓度华蟾素组抑瘤率较丝裂霉素组及低浓度华蟾素组高;TUNEL法检测高浓度华蟾素组AI值为(24.21±1.24)％,较其他各组AI值明显增高,提示高浓度华蟾素组凋亡指数高于丝裂霉素及低浓度华蟾素组.结论 华蟾素对膀胱肿瘤有抑制生长、促进凋亡的作用,且高浓度时抑瘤作用及促凋亡作用较强.     

Increased activation of blood coagulation in pregnant women with the Factor V Leiden mutation

Background

The risk of venous thromboembolism is enhanced in pregnant carriers of the Factor V Leiden mutation. The primary aim of the study was to compare prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels in pregnant Factor V Leiden mutation carriers with those in non-carriers. Secondary aims were to evaluate whether these biomarkers could predict placenta-mediated complications or venous thromboembolism, and to study blood coagulation after caesarean section with thromboprophylaxis and after vaginal delivery without thromboprophylaxis.

Material/Methods

Prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels were studied longitudinally in 476 carriers with singleton pregnancies from gestational weeks 23–25 until 8–10 weeks postpartum.

Results

Prothrombin fragments 1 + 2 and D-dimer levels gradually increased during pregnancy. D-dimer levels were higher in carriers, both during pregnancy and puerperium, compared to non-carriers. D-dimer levels above 0.5 mg/l were found in about 30% and 20% of the heterozygous carriers at 4–5 and 8–10 weeks postpartum, respectively. Soluble fibrin levels were mainly unchanged during pregnancy, with no difference between carriers and non-carriers. Biomarker levels were similar in carriers with uncomplicated and complicated pregnancies.

Conclusion

Higher D-dimer levels indicate increased blood coagulation and fibrinolysis activity in carriers. The high proportion of carriers with D-dimer levels exceeding 0.5 mg/l postpartum must be considered when assessing the probability of venous thromboembolism. Large overlaps in biomarker levels in normal and complicated pregnancies suggest that these biomarkers cannot be used as predictors. Thromboprophylaxis following caesarean section may prevent increased activation of blood coagulation.     

Sex differences in circadian timing systems: Implications for disease

Virtually every eukaryotic cell has an endogenous circadian clock and a biological sex. These cell-based clocks have been conceptualized as oscillators whose phase can be reset by internal signals such as hormones, and external cues such as light. The present review highlights the inter-relationship between circadian clocks and sex differences. In mammals, the suprachiasmatic nucleus (SCN) serves as a master clock synchronizing the phase of clocks throughout the body. Gonadal steroid receptors are expressed in almost every site that receives direct SCN input. Here we review sex differences in the circadian timing system in the hypothalamic–pituitary–gonadal axis (HPG), the hypothalamic–adrenal–pituitary (HPA) axis, and sleep–arousal systems. We also point to ways in which disruption of circadian rhythms within these systems differs in the sexes and is associated with dysfunction and disease. Understanding sex differentiated circadian timing systems can lead to improved treatment strategies for these conditions.     

Protective effect of N-acetylcysteine against BDE-209-induced neurotoxicity in primary cultured neonatal rat hippocampal neurons in vitro

Globally, brominated diphenyl ether-209 (BDE-209) is the most widely used polybrominated diphenyl ether (PBDEs). It has been reported that BDE-209 induces developmental neurotoxicity in vivo. The purpose of this study was to use an antioxidant, N-acetylcysteine (NAC), as an antidote for the neurotoxic effect of BDE-209. We used primary hippocampal neurons from rats for the in vitro cultures. BDE-209 was added to the cultures in increasing concentrations and co-cultured with NAC in order to assess the effect of NAC on BDE-209-induced neurotoxicity. We measured cell viability, apoptosis, expression of phosphorylated p38 mitogen-activated protein kinases (MAPK), intracellular calcium content, and intracellular reactive oxygen species (ROS) levels. The difference between the BDE-209 groups without NAC and the blank control groups was significant (P < 0.05). The difference between the NAC treatment groups and the BDE-209 groups without NAC was also significant (P < 0.05), showing that BDE-209 increased apoptosis, the expression of p38 MAPK, the calcium ion concentration, and the ROS level and decreased cell viability. In contrast, NAC reduced the degree of cellular cytotoxicity induced by BDE-209. The results suggested that NAC may be able to attenuate BDE-209-induced neurotoxicity.     

The role of BDNF and HPA axis in the neurobiology of burnout syndrome

Chronic stress is known to affect the HPA axis. The few clinical studies which have been conducted on HPA-axis function in burnout have produced inconsistent results. The etiological relationship between sBDNF and burnout has not yet been studied. The aim of the current study was to investigate the role of BDNF and HPA axis in the neurobiology of burnout. In the current study 37 clinically diagnosed burnout participants were compared with 35 healthy controls in terms of BDNF, HPA axis, burnout symptoms, depression, anxiety and psychosomatic complaints. Basal serum cortisol, sBDNF and cortisol level after 1 mg DST was sampled. We found no significant differences in terms of HPA-axis function (for basal serum cortisol, p=0.592; for cortisol level after 1 mg DST, p=0.921), but we did find lowered sBDNF levels in burnout group (88.66+/-18.15 pg/ml) as compared to healthy controls (102.18+/-20.92 pg/ml) and the difference was statistically significant (p=0.005). Logistic Regression Analysis revealed that emotional exhaustion (p=0.05), depersonalization (p=0.005) and depression (p=0.025) were significantly associated with burnout. sBDNF levels correlated negatively with emotional exhaustion (r=-,268, p=0.026), depersonalization (r=-,333, p=0.005) and correlated positively with competence (r=0.293, p=0.015) sub-scales of burnout inventory. However, there were no significant relationships between cortisol levels and sBDNF levels (r=0.80, p=0.51), depression, anxiety, psychosomatic complaints and burnout inventory. Our results suggest that low BDNF might contribute to the neurobiology of burnout syndrome and it seems to be associated with burnout symptoms including altered mood and cognitive functions.     

Measurement of thrombin generation intra-operatively and its association with bleeding tendency after cardiac surgery

Introduction

Patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) are susceptible to haemostatic disturbances. Monitoring the haemostatic capacity by conventional clotting tests is challenging.

Materials and Methods

Thrombin generation (TG) by Calibrated Automated Thrombography, clotting tests and tissue factor pathway inhibitor (TFPI) measurements were performed to describe the relationship between haemostatic changes and alterations in these tests. Blood samples were collected before, during and after CPB. Furthermore, it was investigated whether TG measured intraoperatively, is associated with increased risk of bleeding postoperatively.

Results

TG diminished significantly (p < 0.01) after heparinization in the presence and absence of platelets (37% and 50%) compared to baseline. After the start of CPB, TG elevated and persisted till the end of surgery but remained lower than preoperatively. Activated clotting time increased after heparinization and after the start of bypass compared to baseline (400% and 500%). Anti-FXa activity reduced on the start of CPB compared to the level after heparinization, to almost the baseline value following protamine reversal of heparin. The plasma levels of total and free TFPI elevated 9 and 14 fold during bypass and remained after protamine administration higher than preoperatively. Plasma D-dimer levels reduced (p < 0.01) when bypass started. However, a marked elevation was observed in the following time points. TG in platelet-rich plasma measured after heparinization and after the start of CPB associated (p < 0.05) with postoperative blood loss.

Conclusions

TG can be determined during CPB despite the high heparinization level, it reflects the haemostatic capacity better than clotting-based assays and might better predict bleeding when performed intraoperatively.     

Tamoxifen induces resistance to activated protein C

Introduction

The estrogen antagonist tamoxifen (TAM) increases the thrombotic risk similar to estrogen containing oral contraceptives (OC). In OC users this risk is attributed to alterations of hemostasis resulting in acquired resistance to activated protein C (APC). TAM-induced APC resistance has not been reported yet.

Materials and Methods

Blood samples were collected prospectively from women with breast cancer before (n = 25) and monthly after start of adjuvant TAM treatment (n = 75). APC resistance was evaluated on basis of the effect of APC on the endogenous thrombin generation potential. To detect increased in vivo APC generation APC plasma levels were measured using a highly sensitive oligonucleotide-based enzyme capture assay. Routine hemostasis parameters were measured additionally.

Results

APC sensitivity decreased by 41% (p = 0.001) compared to baseline after one month of TAM application and remained significantly decreased during the study period. Free protein S increased (p = 0.008) while other analyzed procoagulant factors, inhibitors, and activation markers of coagulation decreased or did not change significantly. In five patients the APC concentration increased to non-physiological levels but an overall significant increase of APC was not observed.

Conclusions

This is the first study showing acquired APC resistance under TAM therapy. Acquired APC resistance might explain the increased thrombotic risk during TAM treatment. Observed changes of hemostasis parameters suggest different determinants of TAM-induced APC resistance than in OC-induced APC resistance. The presence of acquired APC resistance in TAM patients warrants further evaluation if these patients may benefit from antithrombotic prophylaxis in the presence of additional thrombotic risk factors.     

The lowest VE/VCO2 ratio best identifies chronic thromboembolic pulmonary hypertension

Introduction

The natural history of acute pulmonary embolism (PE) under treatment is about a gradual resolution of the thrombi, and uncommonly, the development of chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that ventilatory efficiency parameters during cardiopulmonary exercise testing (CPET) may be able to monitor the process and predict CTEPH.

Methods

15 patients rehabilitated from acute PE (total resolution of thrombi), 44 patients with chronic PE (with residual thrombi), 66 patients with CTEPH, and 36 sedentary healthy controls performed incremental CPET.

Results

The lowest VE/VCO₂ was higher in CTEPH patients than that in chronic PE and rehabilitated patients (43.4 L/min vs 29.9 L/min vs 27.1 L/min, p < 0.005). The VE/VCO₂ slope (48.4 L/min/L/min vs 29.9 L/min/L/min vs 28.0 L/min/L/min, p < 0.005) and oxygen uptake efficiency plateau (OUEP) (37.1 L/min vs 27.0 L/min vs 25.2 L/min, p < 0.005) had the similar changes. In logistic regression analysis, the lowest VE/VCO₂ ≥ 34.35 L/min was the best predictor of CTEPH (OR 159.0, 95% CI 36.0-702.3, p < 0.001). The lowest VE/VCO₂ was higher in chronic PE patients compared with the controls (29.9 L/min vs 26.5 L/min, p < 0.05), but there was no difference between the rehabilitated patients and the controls. In multiple linear regression analysis, the percentage of vascular obstruction by ventilation-perfusion lung scanning (PVO) was the most significant independent predictor for indices of ventilatory efficiency in chronic PE and rehabilitated patients.

Conclusions

CTEPH is associated with weakened ventilatory efficiency. The lowest VE/VCO2 ratio has the best capability to predict CTEPH. Ventilatory inefficiency improves along with recovery of acute PE.     

Echocardiographic evolution of pulmonary artery pressure after acute pulmonary embolism. Results from IPER registry

Aims

The aim of the study is to describe the course of the echocardiographically measured pulmonary artery systolic pressure (PAsP) in a series of patients included in the Italian Pulmonary Embolism Registry (IPER).

Methods

Patients with confirmed PE received an echo-Doppler evaluation within 24 hours from hospital admission and after one year. Pulmonary hypertension (PH) was considered “likely” , “possible” or “unlikely” with a right ventricular-right atrial (RV-RA) pressure gradient > 45 mm Hg, between 32 and 45 mm Hg and ≤ 31 mm Hg and no additional echocardiographic variables suggestive of PH, respectively.

Results

We studied 286 patients (169 females and 117 males, mean age 67 ± 15; mean follow-up 387 ± 45 days): 240 had a baseline tricuspid regurgitation (TR) and a RV-RA gradient of variable degree. PH was considered likely, unlikely and possible in 97, 93 and 50 patients respectively. At FU echocardiography, 6 patients (2.1%) had a likely PH and all of them were part of the group of 97 patients with a baseline likely PH; 24 patients (8.4%) had a possible PH, and 67% of them had an initial likely PH. No patients with a baseline unlikely PH or without TR developed a follow-up PH (both likely or possible). The probability to show a likely PH at FU echocardiography for patients with a baseline RV-RA gradient > 45 mm Hg was 6.2%, while the probability not to have a likely PH for patients with a baseline RV-RA gradient ≤ 45 mm Hg was 100%.

Conclusion

In our study population of patients with acute PE, we observed that those presenting with a baseline echocardiographic RV-RA pressure gradient ≤ 45 mm Hg were completely free from a likely PH after 1-year.