A preliminary study on the reference intervals of serum tumor marker in apparently healthy elderly population in southwestern China using real-world data.

BACKGROUND: The aim is to establish and verify reference intervals (RIs) for serum tumor markers for an apparently healthy elderly population in Southwestern China using an indirect method. METHODS: Data from 35,635 apparently healthy elderly individuals aged 60 years and above were obtained in West China Hospital from April 2020 to December 2021. We utilized the Box-Cox conversion combined with the Tukey method to normalize the data and eliminate outliers. Subgroups are divided according to gender and age to examine the division of RIs. The Z-test was used to compare differences between groups, and 95% distribution RIs were calculated using a nonparametric method. RESULTS: In the study, we observed that the RIs for serum ferritin and Des-γ-carboxy prothrombin (DCP) were wider for men, ranging from 64.18 to 865.80 ng/ml and 14.00 to 33.00 mAU/ml, respectively, compared to women, whose ranges were 52.58 to 585.88 ng/ml and 13.00 to 29.00 mAU/ml. For other biomarkers, the overall RIs were established as follows: alpha-fetoprotein (AFP) 0-6.75 ng/ml, carcinoembryonic antigen (CEA) 0-4.85 ng/ml, carbohydrate antigen15-3 (CA15-3) for females 0-22.00 U/ml, carbohydrate antigen19-9 (CA19-9) 0-28.10 U/ml, carbohydrate antigen125 (CA125) 0-20.96 U/ml, cytokeratin 19 fragment (CYFRA21-1) 0-4.66 U/ml, neuron-specific enolase (NSE) 0-19.41 ng/ml, total and free prostate-specific antigens (tPSA and fPSA) for males 0-5.26 ng/ml and 0-1.09 ng/ml. The RIs for all these biomarkers have been validated through our rigorous processes. CONCLUSION: This study preliminarily established 95% RIs for an apparently healthy elderly population in Southwestern China. Using real-world data and an indirect method, simple and reliable RIs for an elderly population can be both established and verified, which are suitable for application in various clinical laboratories.

Diagnostic and prognostic performances of GALAD score in staging and 1-year mortality of hepatocellular carcinoma: A prospective study.

BACKGROUND: The GALAD score has improved early hepatocellular carcinoma (HCC) detection rate. The role of the GALAD score in staging and predicting tumor characteristics or clinical outcome of HCC remains of particular interest. AIM: To determine the diagnostic/prognostic performances of the GALAD score at various phases of initial diagnosis, tumor features, and 1-year mortality of HCC and compare the performance of the GALAD score with those of other serum biomarkers. METHODS: This prospective, diagnostic/prognostic study was conducted among patients with newly diagnosed HCC at the liver center of Vajira Hospital. Eligible patients had HCC staging allocation using the Barcelona Clinic Liver Cancer (BCLC) categorization. Demographics, HCC etiology, and HCC features were recorded. Biomarkers and the GALAD score were obtained at baseline. The performance of the GALAD score and biomarkers were prospectively assessed. RESULTS: Exactly 115 individuals were diagnosed with HCC. The GALAD score increased with disease severity. Between BCLC-0/A and BCLC-B/C/D, the GALAD score predicted HCC staging with an area under the curve (AUC) of 0.868 (95%CI: 0.80-0.93). For identifying the curative HCC, the AUC of GALAD score was significantly higher than that of Alpha-fetoprotein (AFP) (0.753) and Lens culinaris agglutinin-reactive fraction of AFP-L3 (0.706), and as good as that of Protein induced by vitamin K absence-II (PIVKA-II) (0.897). For detecting aggressive features, the GALAD score gave an AUC of 0.839 (95%CI: 0.75-0.92) and significantly outperformed compared to that of AFP (0.761) and AFP-L3 (0.697), with a trend of superiority to that of PIVKA-II (0.772). The performance to predict 1-year mortality of GALAD score (AUC: 0.711, 95%CI: 0.60-0.82) was better than that of AFP (0.541) and as good as that of PIVKA-II (0.736). The optimal cutoff value of GALAD score was ≥ 6.83, with a specificity of 72.63% for exhibiting substantial reduction in the 1-year mortality. CONCLUSION: The GALAD model can diagnose HCC at the curative stage, including the characteristic of advanced disease, more than that by AFP and AFP-L3, but not PIVKA-II. The GALAD score can be used to predict the 1-year mortality of HCC.

Vitamin K Status Based on K1, MK-4, MK-7, and Undercarboxylated Prothrombin Levels in Adolescent and Adult Patients with Cystic Fibrosis: A Cross-Sectional Study.

The available evidence on vitamin K status in cystic fibrosis (CF) is scarce, lacking data on vitamin K2 (menaquinones-MK). Therefore, we assessed vitamin K1, MK-4 and MK-7 concentrations (LC-MS/MS) in 63 pancreatic insufficient and modulator naïve CF patients, and compared to 61 healthy subjects (HS). Vitamin K1 levels did not differ between studied groups. MK-4 concentrations were higher (median <1st-3rd quartile>: 0.778 <0.589-1.086> vs. 0.349 <0.256-0.469>, p < 0.0001) and MK-7 levels lower (0.150 <0.094-0.259> vs. 0.231 <0.191-0.315>, p = 0.0007) in CF patients than in HS. MK-7 concentrations were higher in CF patients receiving K1 and MK-7 supplementation than in those receiving vitamin K1 alone or no supplementation. Moreover, vitamin K1 concentrations depended on the supplementation regime. Based on multivariate logistic regression analysis, we have found that MK-7 supplementation dose has been the only predictive factor for MK-7 levels. In conclusion, vitamin K1 levels in CF are low if not currently supplemented. MK-4 concentrations in CF patients supplemented with large doses of vitamin K1 are higher than in HS. MK-7 levels in CF subjects not receiving MK-7 supplementation, with no regard to vitamin K1 supplementation, are low. There do not seem to be any good clinical predictive factors for vitamin K status.

The Usefulness of Vitamin K-Dependent Proteins in the Diagnosis of Colorectal Carcinoma.

Colorectal cancer (CRC) is one of the most common neoplasms in developed countries, with increasing incidence and mortality, even in young people. A variety of serum markers have been associated with CRC (CEA, CA 19-9), but neither should be used as a screening tool for the diagnosis or evolution staging of CRC. The sensitivity and specificity of these markers are not as good as is required, so new ones need to be found. Matrix Gla protein and PIVKA II are involved in carcinogenesis, but few studies have evaluated their usefulness in predicting the presence and severity of CRC. Two hundred patients were divided into three groups: 80 patients were included in the control group; 80 with CRC and without hepatic metastasis were included in Group 1; 40 patients with CRC and hepatic metastasis were included in Group 2. Vitamin K-dependent proteins (VKDPs) levels in plasma were determined. Patients with CRC without methastasis (Group 1) and CRC patients with methastasis (Group 2) presented significantly higher values of CEA, CA 19-9, PIVKA II (310.05 ± 38.22 vs. 430.13 ± 122.13 vs. 20.23 ± 10.90), and ucMGP (14,300.00 ± 2387.02 vs. 13,410.52 ± 2243.16 vs. 1780.31 ± 864.70) compared to control group (Group 0). Interestingly, Group 1 presented the greatest PIVKA II values. Out of all the markers, significant differences between the histological subgroups were found only for ucMGP, but only in non-metastatic CRC. Studying the discrimination capacity between the patients with CRC vs. those without, no significant differences were found between the classical tumor markers and the VKDP AUROC curves (PIVKA II and ucMGP AUROCs = 1). For the metastatic stage, the sensitivity and specificity of the VKDPs were lower in comparison with those of CA 19-9 and CEA, respectively (PIVKA II AUROC = 0.789, ucMGP AUROC = 0.608). The serum levels of these VKDPs are significantly altered in patients with colorectal carcinoma; it is possible to find additional value of these in the early stages of the disease.

The Etiology of the Thrombotic Phenomena Involved in the Process of Coronary Artery Disease-What Is the Role of Thrombophilic Genes in the Development of This Pathology?

Cardiovascular diseases, among which includes coronary artery disease, represent one of the most important causes of mortality and morbidity worldwide. Research aimed at determining the risk factors involved recognizes a group of "traditional" risk factors, but also more recent studies identified over 100 "novel" ones which may have a role in the disease. Among the latter is the thrombophilia profile of a patient, a pathology well-established for its involvement in venous thromboembolism, but with less studied implications in arterial thrombosis. This paper reviews the literature, explaining the pathophysiology of the thrombophilia causes associated most with coronary thrombosis events. Results of several studies on the subject, including a meta-analysis with over 60,000 subjects, determined the significant involvement of factor V Leiden, prothrombin G20210A mutation, plasminogen activator inhibitor-1 and antiphospholipid syndrome in the development of coronary artery disease. The mechanisms involved are currently at different stages of research, with some already established and used as therapeutic targets.

GALAD score as a prognostic model for recurrence of hepatocellular carcinoma after local ablation.

BACKGROUND: Currently, the high recurrence rate still forms severe challenges in hepatocellular carcinoma (HCC) treatment. The GALAD score, including age, gender, alpha-fetoprotein (AFP), lens culinaris agglutinin-reactive AFP (AFP-L3), and des-gamma-carboxyprothrombin (DCP) was developed as a diagnostic model. However, evidence is still lacking to confirm the capability of the GALAD score to predict the recurrence of HCC. METHODS: This study included 390 HCC patients after local ablation at Beijing You'an Hospital from January 1, 2018, to December 31, 2022. Firstly, the area under the receiver operating characteristic (ROC) curve (AUC) was calculated to assess the predictive capability of the GALAD score. Then, the Kaplan-Meier (KM) curve and log-rank test were used to compare the prognosis between two groups classified by GALAD score. Finally, a nomogram for high-risk patients was established by Lasso-Cox regression. It was assessed by ROC curves, calibration curves, and decision curve analysis (DCA). RESULTS: The ROC curve (AUC: 0.749) and KM curve showed the GALAD score had good predictive ability and could clearly stratify patients into two groups through the risk of recurrence. Prognostic factors selected by Lasso-Cox regression contained tumor number, tumor size, and globulin. The nomogram for high-risk patients showed reliable discrimination, calibration, and clinical utility. CONCLUSION: This research displayed that the GALAD score is an effective model for predicting the recurrence of HCC. Meanwhile, we found the poor prognosis of the high-risk group and created a nomogram for these patients.

Development and validation of a predictive model for poor prognosis of communication disorders in children with cerebral palsy after cervical perivascular sympathectomy.

Cervical perivascular sympathectomy (CPVS) can improve communication disorders in children with cerebral palsy (CP); however, there are no research reports on the factors affecting surgical efficacy. This study aimed to establish a nomogram for poor prognosis after CPVS. We collected data from 313 CP patients who underwent CPVS at the Neurosurgery Cerebral Palsy Center of the Second Affiliated Hospital of Xinjiang Medical University from January 2019 to January 2023. Among them, 70% (n = 216) formed the training cohort and 30% (n = 97) the validation cohort. The general data and laboratory examination data of both groups were analyzed. In training cohort, 82 (37.96%) showed improved postoperative communication function. Logistic analysis identified motor function, serum alkaline phosphatase, serum albumin, and prothrombin activity as the prognostic factors. Using these four factors, a prediction model was constructed with an area under the curve (AUC) of 0.807 (95% confidence interval [CI], 0.743-0.870), indicating its ability to predict adverse outcomes after CPVS. The validation cohort results showed an AUC of 0.76 (95% CI, 0.650-0.869). The consistency curve and Hosmer-Lemeshow test (χ2 = 10.988 and p = 0.202, respectively) demonstrated good consistency between the model-predicted incidence and the actual incidence of poor prognosis. Motor function, serum alkaline phosphatase, serum albumin, and prothrombin activity are independent risk factors associated with the prognosis of communication disorders after CPVS. The combined prediction model has a good clinical prediction effect and has promising potential to be used for early prediction of prognosis of CPVS.

Risk Factors of Thrombophilia-Related Mutations for Early and Late Pregnancy Loss.

Background and Objectives: This retrospective cohort study investigates the role of genetic thrombophilia in pregnant women experiencing early pregnancy loss compared to those with late pregnancy loss. Materials and Methods: Participants were categorized into early and late pregnancy loss groups based on gestational age. A total of 156 patients were included, out of which 103 had early-trimester pregnancy losses and 96 had multiple miscarriages. Results: The study revealed a synergistic effect of Factor V Leiden (FVL G1691A) and Methylenetetrahydrofolate Reductase (MTHFR C677T) mutations (coefficient 3.42). Prothrombin (PT) G20210A and ß-Fibrinogen 455 G>A mutations exhibited a significant interaction (coefficient 1.98). Additionally, MTHFR A1298C and Plasminogen Activator Inhibitor-1 (PAI-1 4G/5G) mutations showed a significant interaction (coefficient 1.65). FVL G1691A and Endothelial Protein C Receptor (EPCR) allele A1/A2 mutations also demonstrated a significant association (coefficient 2.10). Lastly, MTHFR C677T and Glycoprotein IIb/IIIa T1565C mutations interacted significantly (coefficient 1.77). Risk factor analysis identified several mutations associated with early pregnancy loss, including PAI-1 4G/5G homozygous (OR 3.01), FVL G1691A heterozygous (OR 1.85), and MTHFR A1298C heterozygous (OR 1.55). Both homozygous and heterozygous MTHFR C677T mutations were significant risk factors (OR 2.38; OR 2.06), as was PT G20210A homozygous mutation (OR 1.92). The PAI-1 4G/4G homozygous variant posed a risk (OR 1.36). Late pregnancy loss was associated with MTHFR A1298C homozygous mutation (OR 3.79), ß-Fibrinogen 455 G>A heterozygous mutation (OR 2.20), and MTHFR A1298C heterozygous mutation (OR 2.65). Factor XIII G1002T heterozygous mutation (OR 1.18) and PAI-1 4G/5G homozygous mutation (OR 2.85) were also significant risk factors. EPCR allele A1/A2 (OR 1.60) and A2/A3 (OR 1.73) mutations were identified as significant risk factors for late pregnancy loss. Furthermore, FVL G1691A homozygous mutation, PT G20210A homozygous mutation, MTHFR C677T heterozygous mutation, MTHFR A1298C heterozygous mutation, and EPCR allele A1/A2 were identified as significant risk factors for multiple miscarriage. Conclusions: This study highlights significant interactions and risk factors related to genetic thrombophilia mutations in different types of pregnancy loss, contributing valuable insights for miscarriage management guidelines.

Diagnostic performance of PIVKA-II in identifying recurrent hepatocellular carcinoma following curative resection: a retrospective cohort study.

Protein induced by vitamin K absence or antagonist II (PIVKA-II) plays a critical role in the diagnosis of hepatocellular carcinoma (HCC), however, studies on its efficacy in diagnosing recurrent HCC were rarely found. A multicenter, retrospective, and observational study was conducted. During the overall follow-up of 5 years, HCC patients who had curative resection were monitored every 3 months in the first year post-surgery and every 6 months thereafter if no recurrence occurred. Tumor markers were collected at the diagnosis of recurrence for those with recurrence and at the last follow-up for those without recurrence. The median serum levels of PIVKA-II and AFP in the recurrence group were significantly higher than those in the non-recurrence group (PIVKA-II: 84.62 vs. 18.76 mAU/ml, p < 0.001; AFP: 4.90 vs. 3.00 ng/ml, p < 0.001) and there is a significant correlation between PIVKA-II and AFP (R = 0.901, p < 0.001). PIVKA-II showed better accuracy than AFP in the diagnosis of overall recurrent HCC (AUC: 0.883 vs. 0.672; p < 0.0001), but also in patients with negative PIVKA-II before curative resection (AUC: 0.878 vs. 0.680, p = 0.001). Clinician should pay more attention to serum PIVKA-II values when following patients after curative HCC resection to detect early recurrence.Clinical trial registration: ChiCTR2300070874.

Construction of an immunosensor based on Cys/Au@TiO2 modification for the detection of liver cancer marker PIVKA-II.

An ultrasensitive immunosensor of Cys/Au@TiO2 based on disposable screen-printed electrodes (SPE) for PIVKA-II detection for hepatocellular carcinoma (HCC) diagnosis was developed by utilizing Cystine (Cys) and nanocomposite Au@TiO2. Firstly, HAuCl4 underwent a reduction reaction with NaBH4, then Au nanoparticles were coated onto TiO2 nanoparticles. Followed, Cys/Au@TiO2 was formed through self-assembly of cysteine to allow the monoclonal antibody of abnormal thrombospondin to bound to the amino group on the surface of the composite by covalent bonding. The mechanism is to determine the changes in the current of the sensor caused by the specific binding of the abnormal prothrombin monoclonal antibody adsorbed by the complex with its antigen. The Cys/Au@TiO2 immunosensor was fully characterized by various analytical approaches and it showed a wide linear testing range of 1-10000 pg mL-1 (R2 = 0.991) and the limit of detection down to 0.77 pg ml-1, with highly sensitivity and specificity. The results showed that the developed immunosensor platform can effectively detect trace amounts of PIVKA-II protein and has potent clinical application for HCC diagnosis.

PANC-1 Cell Line as an Experimental Model for Characterizing PIVKA-II Production, Distribution, and Molecular Mechanisms Leading to Protein Release in PDAC.

Pancreatic ductal adenocarcinoma (PDAC) represents a highly aggressive malignancy with a lack of reliable diagnostic biomarkers. Protein induced by vitamin K absence (PIVKA-II) is a protein increased in various cancers (particularly in hepatocellular carcinoma), and it has recently exhibited superior diagnostic performance in PDAC detection compared to other biomarkers. The aim of our research was to identify an in vitro model to study PIVKA-II production, distribution, and release in PDAC. We examined the presence of PIVKA-II protein in a panel of stabilized pancreatic cancer cell lines by Western blot analysis and indirect immunofluorescence (IFA). After quantitative evaluation of PIVKA-II in PaCa 44, H-Paf II, Capan-1, and PANC-1, we adopted the latter as a reference model. Subsequently, we analyzed the effect of glucose addiction on PIVKA-II production in a PANC-1 cell line in vitro; PIVKA-II production seems to be directly related to an increase in glucose concentration in the culture medium. Finally, we evaluated if PIVKA-II released in the presence of increasing doses of glucose is concomitant with the expression of two well-acknowledged epithelial-mesenchymal transition (EMT) markers (Vimentin and Snail). According to our experimental model, we can speculate that PIVKA-II release by PANC-1 cells is glucose-dependent and occurs jointly with EMT activation.

A simple method to resolve rate constants when the binding mechanism obeys induced fit or conformational selection.

Many interactions involving a ligand and its molecular target are studied by rapid kinetics using a stopped-flow apparatus. Information obtained from these studies is often limited to a single, saturable relaxation that is insufficient to resolve all independent rate constants even for a two-step mechanism of binding obeying induced fit (IF) or conformational selection (CS). We introduce a simple method of general applicability where this limitation is overcome. The method accurately reproduces the rate constants for ligand binding to the serine protease thrombin determined independently from the analysis of multiple relaxations. Application to the inactive zymogen precursor of thrombin, prethrombin-2, resolves all rate constants for a binding mechanism of IF or CS from a single, saturable relaxation. Comparison with thrombin shows that the prethrombin-2 to thrombin conversion enhances ligand binding to the active site not by improving accessibility through the value of kon but by reducing the rate of dissociation koff. The conclusion holds regardless of whether binding is interpreted in terms of IF or CS and has general relevance for the mechanism of zymogen activation of serine proteases. The method also provides a simple test of the validity of IF and CS and indicates when more complex mechanisms of binding should be considered.

Homozygous MTHFR C677T carriers develop idiopathic portal vein thrombosis 20 years earlier than wild type.

The aim of this study was to evaluate the impact of methylene tetrahydrofolate reductase (MTHFR) rs1801133 (C→T667 transition) on age at first idiopathic portal vein thrombosis (PVT) and to identify clinical and/or laboratory variables influencing age at first PVT, including plasma homocysteine and the prothrombin rs1799963 PT (G→A transition at position 20210) (PT) mutation. A retrospective cross-sectional cohort, including 15 MTHFR TT, 32 MTHFR TC and 22 MTHFR CC idiopathic PVT participants contributing demographics, age at PVT, plasma concentrations of homocysteine and of natural anticoagulants. MTHFR TT carriers presented with a lower age at PVT than heterozygous or wild-type genotypes (31 ±â€Š8 vs. 48 ±â€Š15 vs. 52 ±â€Š13 years, P  = 0.001) and were more likely to have a plasma HC concentration above the cut-off (73.3 vs. 32 vs. 50%, P  = 0.04). MTHFR TT and protein C predicted age at PVT ( P  < 0.0001 and P  = 0.06); MTHFR TT predicted plasma homocysteine ( P  = 0.05). In the MTHFR TT group, plasma homocysteine inversely related to protein C ( P  = 0.03). Plasma homocysteine predicted the extent of PVT ( P  = 0.03). Compound MTHFR TT + PT GA did not lower age at first PVT compared to MTHFR TT alone (35 ±â€Š9 vs. 30 ±â€Š8 years). MTHFR TT is associated with a 20-year earlier PVT presentation than heterozygous and wild-type MTHFR genotypes. The inverse relation between plasma homocysteine and protein C contributes to the prematurity of PVT in the MTHFR TT group, whereas plasma homocysteine contributes to the extent of PVT. The recent exclusion of MTHFR genotyping from the thrombophilia screen needs revisiting in this setting.

Cryo-EM structure and functional basis of prothrombin recognition by a type I antiprothrombin antiphospholipid antibody.

ABSTRACT: Antiprothrombin antibodies are found in antiphospholipid patients, but how they interact with prothrombin remains elusive. Prothrombin adopts closed and open forms. We recently discovered type I and type II antibodies and proposed that type I recognizes the open form. In this study, we report the discovery and structural and functional characterization in human plasma of a type I antibody, POmAb (prothrombin open monoclonal antibody). Using surface plasmon resonance and single-molecule spectroscopy, we show that POmAb interacts with kringle-1 of prothrombin, shifting the equilibrium toward the open form. Using single-particle cryogenic electron microscopy (cryo-EM), we establish that the epitope targeted by POmAb is in kringle-1, comprising an extended binding interface centered at residues R90-Y93. The 3.2-Å cryo-EM structure of the complex reveals that the epitope overlaps with the position occupied by the protease domain of prothrombin in the closed state, explaining the exclusive binding of POmAb to the open form. In human plasma, POmAb prolongs phospholipid-initiated and diluted Russell's viper venom clotting time, which could be partly rescued by excess phospholipids, indicating POmAb is an anticoagulant but exerts a weak lupus anticoagulant effect. These studies reveal the structural basis of prothrombin recognition by a type I antiphospholipid antibody and uncover an exciting new strategy to achieve anticoagulation in human plasma.

Thrombophilia genetic mutations and their relation to disease severity among patients with COVID-19.

OBJECTIVES: Patients with COVID-19 infection appear to develop virus-induced hypercoagulability resulting in numerous thrombotic events. The aim of the present study was to determine the relationship between the thrombophilia genes mutations (prothrombin G20210A, factor V Leiden, and methyltetrahydrofolate reductase (MTHFR)) and the severity of COVID-19 patients. DESIGN: Prospective cross-sectional study. METHOD: One hundred and forty patients (80 adults and 60 children) were included in the current study. They were divided into the severe COVID-19 group and the mild COVID-19 group, with each group comprising 40 adults and 30 children. The patients were assessed for FV R506Q, FV R2H1299R, MTHFR A1298C, MTHFR C677T, and prothrombin gene G20210A polymorphisms. CBC, D-dimer, renal and liver function tests, hs-CRP, ferritin, and LDH were also assessed. Thrombotic events were clinically and radiologically documented. RESULTS: Severe COVID-19 cases were significantly more frequent to have a heterozygous mutation for all the studied genes compared to mild COVID-19 cases (p<0.05 for all). Being mutant to gene FV R506Q carried the highest risk of developing a severe disease course (p<0.0001). Patients with abnormally high D-dimer levels were significantly more frequent to be heterozygous for FV R506Q, FV R2H1299R, and prothrombin gene G20210A (p = 0.006, 0.007, and 0.02, respectively). CONCLUSION: We concluded that there is an evident relationship between severe COVID-19 and inherited thrombophilia. In the current study, FV R506Q gene mutation carried the highest risk of developing a severe COVID-19 disease course.

Prothrombin conversion and thrombin decay in patients with cirrhosis-role of prothrombin and antithrombin deficiencies.

BACKGROUND: Thrombin generation (TG) in the presence of thrombomodulin (TG-TM) in the plasma of patients with cirrhosis (PWC) is tilted toward a hypercoagulable phenotype. Low protein C and elevated factor VIII levels play a role, but other determinants, such as the prothrombin/antithrombin pair, must also be studied. OBJECTIVES: The objectives were (i) to quantitatively assess the subprocesses (prothrombin conversion and thrombin decay) and (ii) to understand the underlying mechanism by studying TG dynamics after prothrombin and antithrombin plasma level correction in PWC. METHODS: We studied TG-TM in plasma samples of 36 healthy controls (HCs) and 41 PWC with prothrombin and antithrombin levels of <70% and after their correction. We initiated coagulation with an intermediate picomolar concentration of tissue factor. We determined the overall thrombin potential, prothrombin conversion, and thrombin decay. RESULTS: TG-TM was increased in PWC compared with HC due to impaired thrombin inhibition. Indeed, thrombin decay capacity (min-1) decreased from 0.37 (0.35-0.40) in HC to 0.33 (0.30-0.37) in the Child-Turcotte-Pugh A (CTP-A; P = .09), 0.27 (0.26-0.30) in the CTP-B (P < .001), and 0.20 (0.19-0.20) in the CTP-C (P < .001) group. Concomitant correction of prothrombin and antithrombin increased endogenous thrombin potential with prothrombin conversion surpassing thrombin decay. By contrast, when we corrected only antithrombin, TG-TM was normalized and even consistent with a hypocoagulable phenotype in the CTP-C group. CONCLUSION: Our results highlight that in PWC, hypercoagulability (evidenced in the presence of TM) is due to impaired thrombin decay, whereas low prothrombin levels do not translate into decreased prothrombin conversion, likely due to altered TM-activated protein C negative feedback.

Distinguishing characteristics of Staphylococcus schleiferi and Staphylococcus coagulans of human and canine origin.

Staphylococcus schleiferi and Staphylococcus coagulans are opportunistic pathogens of animals and humans. They were previously classified as Staphylococcus schleiferi subs. schleiferi and Staphylococcus schleiferi subs. coagulans, respectively, and recently reclassified as separate species. S. coagulans, is frequently associated with dogs, whereas S. schleiferi is more commonly isolated from humans. Coagulase activity status is a defining characteristic of the otherwise closely related species. However, the use of coagulase tests originally developed to distinguish S. aureus from non-coagulase-producing staphylococci, for this purpose is questionable and the basis for their host preference has not been elucidated. In the current study, a putative coa gene was identified and correlated with coagulase activity measured using a chromogenic assay with human and bovine prothrombin (closely related to canine prothrombin). The results of the tests performed with human prothrombin showed greater reactivity of S. coagulans isolates from humans than isolates obtained from dogs with the same substrate. Our data suggest that unlike S. coagulans isolates from humans, isolates from dogs have more coagulase activity with bovine prothrombin (similar to canine prothrombin) than human prothrombin. Differences in nuc and 16s rRNA genes suggest a divergence in S. coagulans and S. schleiferi. Phenotypic and genotypic variation based on the number of IgG binding domains, and the numbers of tandem repeats in C-terminal fibronectin binding motifs was also found in protein A, and fibronectin-binding protein B respectively. This study identified a coa gene and associated phenotypic activity that differentiates S. coagulans and S. schleiferi and identified key phylogenetic and phenotypic differences between the species.