Thrombin generation in a woman with heterozygous factor V Leiden and combined oral contraceptives: A case report

Thrombomodulin is a stronger indicator of combined oral contraceptives-induced activated protein C pathway resistance in the thrombin generation test than activated protein C

Background

The mechanism by which combined oral contraceptives (COCs) lead to hypercoagulation is not fully understood, although activated protein C (APC) pathway resistance has been implicated. APC and thrombomodulin (TM) tend to be considered as interchangeable reagents, even though their biological action in coagulation is different. However, it remains unclear which reagent is better suited for the detection of APC pathway resistance. We compared the effectiveness of TM and APC in TG to detect COC-induced APC pathway resistance using thrombin generation (TG).

Methods

TG was measured on ST Genesia in 48 healthy women, of whom 24 used COCs. TG was triggered with STG-ThromboScreen (with and without TM), spiked with a low and high concentration of TM or APC (2 or 15 nM TM, or 1.5 or 5.5 nM APC), aimed to achieve 50% and 90% ETP inhibition, respectively.

Results

TG was higher in women using COCs. TM and APC inhibit TG in all women, although their inhibitory effect is more pronounced in women without COC compared to women with COC. The addition of 2 nM TM causes an ETP reduction of 40% (1,289 vs. 768 nM•min) in women without COC and an ETP reduction of 24% (1,704 vs. 1,287 nM•min) in women with COC. The addition of 1.5 nM APC causes an ETP reduction of 41% (1,289 vs. 759 nM•min) in women without COC and an ETP reduction of 23% (1,704 vs. 1,316 nM•min) in women with COC. The difference in effect between women with and without COC is largest when 15 nM TM, aimed at 90% ETP inhibition, is used. 15 nM TM leads to the smallest overlap in ETP inhibition between women with and without COC (27% overlap), compared to 2 nM TM (41% overlap), and 1.5 nM APC (38% overlap) and 5.5 nM APC (41% overlap).

Conclusion

Although TM and APC are often used interchangeably to assess the sensitivity of the APC system in TG, our findings suggest that TM is a better discriminator to detect COC-use induced APC pathway resistance. In addition, we found that the ETP is a better TG test readout for APC pathway resistance testing than the peak height.

External validation of the MidiCAT variant of thrombography: Comparison with calibrated automated thrombography and study of the centrifugation scheme

Introduction

To perform Calibrated Automated Thrombography (CAT), the use of reduced plasma volumes (referred to as “MidiCAT”) makes it possible to more efficiently use limited volumes of valuable biobanked plasma samples and decreases expenses for reagents. It is, however, unclear whether the MidiCAT procedure is suitable when thrombin generation (TG) is studied in the presence of added thrombomodulin (TG-TM). Moreover, a simplified centrifugation scheme would facilitate biobanking, if appropriate, for more sensitive coagulation studies. We aimed to compare the results of “MidiCAT” (halved plasma and reagent volumes) with those from regular CAT, in the absence or presence of TM, as well as to study the impact of a single-centrifugation scheme for plasma preparation before freezing.

Materials and methods

Plasma samples were prepared from the citrated blood from 20 Geneva hospital diverse patients without gross coagulation abnormalities with a single- or double-centrifugation scheme. Samples were kept frozen at −80°C and thawed just before the TG assay in duplicate under two conditions: 1 pM tissue factor (TF) or 5 pM TF + TM.

Results and discussion

(1) We externally validated “MidiCAT” and also extended the validation to TG-TM. Whatever the method (CAT or MidiCAT), intra-assay (assessed with duplicates) CV was below 6% (1 pM TF) or below 10% (5 pM TF + TM) for ETP. Agreement between the MidiCAT and CAT results was satisfactory; the p coefficients were above 0.95 for ETP and above 0.90 for most other parameters; biases for ETP were +10.0% (1 pM FT) and +13.5% (5 pM + TM). (2) The centrifugation scheme markedly affected the results obtained in the presence of TM, whereas the bias and limit of agreement (difference plots) were low for the no TM condition. The bias in the presence of TM was obvious, more marked with plasma samples sensitive to TM when double centrifuged: the lower the ETP-TM, the greater the relative difference between the ETP-TM of plasma samples prepared with just single centrifugation and the reference plasma samples. Thus, a single-centrifugation procedure, as is often used for plasma biobanking, is suitable for TG study only if it is not performed in the presence of TM.

Oral lesions after COVID-19 vaccination: Immune mechanisms and clinical approach

COVID-19 vaccination, although is a promising tool to overcome the pandemic, has side effects. There are increasing reports of oral lesions after COVID-19 vaccination. The aim of this review is to identify the occurrence of some oral lesions after COVID-19 vaccination, and highlight the underlying immune mechanisms involved. A narrative literature review was performed by searching electronic databases including PubMed, Scopus and Web of Science to investigate the oral lesions after COVID-19 vaccination. The inclusion criteria were original studies, including the case reports, case series, letter to the editor, and cross-sectional studies. The exclusion criteria included the studies which examined the oral lesions caused by COVID-19 infection. The information, including the number of participant(s) receiving vaccine, type of vaccine, dose number, side effect(s), time of onset following vaccination, healing time, treatment strategies for the existing lesions, and related mechanisms were then summarized in a data extraction sheet. The results of this review showed that some vaccines had side effects with oral involvement such as pemphigus vulgaris, bullous pemphigoid, herpes zoster, lichen planus, Stevens-Johnson syndrome and Behçet's disease. Future research needs to elucidate the physiopathology of oral manifestations after the COVID-19 vaccination, and better understand the risk factors associated with such responses. Sometimes vaccine's side effects may be due to the nocebo effect, which means that the person expects some adverse events to occur following the vaccine administration.

Side Effects of mRNA-Based and Viral Vector-Based COVID-19 Vaccines among German Healthcare Workers

BACKGROUND

the increasing number of COVID-19 vaccines available to the public may trigger hesitancy or selectivity towards vaccination. This study aimed to evaluate the post-vaccination side effects of the different vaccines approved in Germany; Methods: a cross-sectional survey-based study was carried out using an online questionnaire validated and tested for a priori reliability. The questionnaire inquired about demographic data, medical and COVID-19-related anamneses, and local, systemic, oral, and skin-related side effects following COVID-19 vaccination; Results: out of the 599 participating healthcare workers, 72.3% were females, and 79.1% received mRNA-based vaccines, while 20.9% received a viral vector-based vaccine. 88.1% of the participants reported at least one side effect. Injection site pain (75.6%) was the most common local side effect, and headache/fatigue (53.6%), muscle pain (33.2%), malaise (25%), chills (23%), and joint pain (21.2%) were the most common systemic side effects. The vast majority (84.9%) of side effects resolved within 1-3 days post-vaccination; Conclusions: the mRNA-based vaccines were associated with a higher prevalence of local side effects (78.3% vs. 70.4%; Sig. = 0.064), while the viral vector-based vaccine was associated with a higher prevalence of systemic side effects (87.2% vs. 61%; Sig. < 0.001). Females and the younger age group were associated with an increased risk of side effects either after mRNA-based or viral vector-based vaccines. The gender- and age-based differences warrant further rigorous investigation and standardized methodology.