Prolonged replication of BA.1 and BA.2 Omicron lineages compared to Delta variant in nasopharyngeal samples from COVID-19 patients

OBJECTIVES

We aimed to characterize and compare the viral loads (VL) of the Omicron BA.1 and BA.2 lineages and the Delta variant in nasopharyngeal samples from newly diagnosed COVID-19 patients and their kinetics over time.

PATIENTS AND METHODS

The kinetics of the VL were measured on the CT data from 215 SARS-CoV-2 positive patients who presented at least two positive PCRs a day apart and were screened for SARS-CoV-2 viral lineages.

RESULTS

We observed no significant difference in median CT value during the first diagnostic test between the Delta variant and the two Omicron lineages. However, the kinetics of CT decreases for the BA.1 and BA.2 lineage were significantly lengthier in time than the kinetics for the Delta variant. The BA.2 lineage presented lower median CT value (-2 CT) (inversely proportional to the VL) than the BA.1 lineage.

CONCLUSIONS

BA.2 Omicron lineage presented higher VL than BA.1 Omicron lineage at diagnostic. Omicron BA.1 and BA.2 lineages have more prolonged replication than the Delta variant.

Accuracy assessment of total or IgG Immunoglobulin to hepatitis A virus tests around immunity threshold

BACKGROUND

Anti-hepatitis A virus (HAV) antibody titers at 20 IU/L are assumed to correlate with protection against HAV challenge.

METHODS

We examined the accuracy and precision of currently in use immunoassays for total or anti-HAV IgG determination, by repeated testing of dilutions of the international anti-HAV standard, within a 10-50 IU/mL concentration range.

RESULTS AND CONCLUSION

Eight immunoassays were evaluated. All could confidently identify people who need to be vaccinated, or who might benefit from a booster vaccine: no positive interpretation for the 10 and 15 IU/mL concentrations. However, qualitative interpretation may differ from test to test in the 15-30 IU/mL range. This variation has to be taken into account when comparing seroprevalence data.

Performance of 30 commercial SARS-CoV-2 serology assays in testing symptomatic COVID-19 patients

We report evaluation of 30 assays' (17 rapid tests (RDTs) and 13 automated/manual ELISA/CLIA assay (IAs)) clinical performances with 2594 sera collected from symptomatic patients with positive SARS-CoV-2 rRT-PCR on a respiratory sample, and 1996 pre-epidemic serum samples expected to be negative. Only 4 RDT and 3 IAs fitted both specificity (> 98%) and sensitivity (> 90%) criteria according to French recommendations. Serology may offer valuable information during COVID-19 pandemic, but inconsistent performances observed among the 30 commercial assays evaluated, which underlines the importance of independent evaluation before clinical implementation.

Performance of serum apolipoprotein-A1 as a sentinel of Covid-19

BACKGROUND

Since 1920, a decrease in serum cholesterol has been identified as a marker of severe pneumonia. We have assessed the performance of serum apolipoprotein-A1, the main transporter of HDL-cholesterol, to identify the early spread of coronavirus disease 2019 (Covid-19) in the general population and its diagnostic performance for the Covid-19.

METHODS

We compared the daily mean serum apolipoprotein-A1 during the first 34 weeks of 2020 in a population that is routinely followed for a risk of liver fibrosis risk in the USA (212,297 serum) and in France (20,652 serum) in relation to a local increase in confirmed cases, and in comparison to the same period in 2019 (266,976 and 28,452 serum, respectively). We prospectively assessed the sensitivity of this marker in an observational study of 136 consecutive hospitalized cases and retrospectively evaluated its specificity in 7,481 controls representing the general population.

RESULTS

The mean serum apolipoprotein-A1 levels in the survey populations began decreasing in January 2020, compared to the same period in 2019. This decrease was highly correlated with the daily increase in confirmed Covid-19 cases in the following 34 weeks, both in France and USA, including the June and mid-July recovery periods in France. Apolipoprotein-A1 at the 1.25 g/L cutoff had a sensitivity of 90.6% (95%CI84.2-95.1) and a specificity of 96.1% (95.7-96.6%) for the diagnosis of Covid-19. The area under the characteristics curve was 0.978 (0.957-0.988), and outperformed haptoglobin and liver function tests. The adjusted risk ratio of apolipoprotein-A1 for survival without transfer to intensive care unit was 5.61 (95%CI 1.02-31.0; P = 0.04).

CONCLUSION

Apolipoprotein-A1 could be a sentinel of the pandemic in existing routine surveillance of the general population. NCT01927133, CER-2020-14.

A dictionary learning approach for spatio-temporal characterization of absence seizures

OBJECTIVE

This research explores absence seizures using data recorded from different layers of somatosensory cortex of four genetic absence epilepsy rats from Strasbourg (GAERS). Localizing the active layers of somatosensory cortex (spatial analysis) and investigating the dynamics of recorded seizures (temporal analysis) are the main goals of this research.

APPROACH

We model the spike discharges of seizures using a generative spatio-temporal model. We assume that there are some states under first-order Markovian model during seizures, and each spike is generated when the corresponding state is activated. We also assume that a few specific epileptic activities (or atoms) exist in each state which are linearly combined and form the spikes. Each epileptic activity is described by two characteristics: (1) its spatial topography which shows the organization of current sources and sinks generating the epileptic activity, and (2) its temporal representation which illustrates the activation function of the epileptic activity. We show that the estimation of the model parameters, i.e. states and their epileptic activities (atoms), is similar to solving a dictionary learning problem for sparse representation. Instead of using classical dictionary learning algorithms, a new approach, taking into account the Markovian nature of the model, is proposed for estimating the models parameters, and its efficiency is experimentally verified.

MAIN RESULTS

Experimental results show that there are one dominant and one unstable state with two epileptic activities in each during the seizures (temporal analysis). It is also found that the top and bottom layers of the somatosensory cortex are the most active layers during seizures (spatial analysis). The structural model is similar for all rats with a spatial topography which is the same for all rats but a temporal activation which changes according to the rat.

SIGNIFICANCE

The proposed framework can be applied on any database acquired from a small area of the brain, and can provide valuable spatio-temporal analysis for neuroscientists.

Chronic hepatitis E in a heart transplant patient: sofosbuvir and ribavirin regimen not fully effective

Hepatitis E virus (HEV) can induce chronic infections in the case of immunosuppression, which are sometimes not cured with ribavirin. Furthermore, sofosbuvir is a highly potent inhibitor of HCV polymerase and was shown to inhibit HEV genotype-3 replication in vitro. We report here the outcome of sofosbuvir/ribavirin therapy on a chronic HEV infection in a heart transplant recipient non-responder to ribavirin. After 24 weeks, the regimen failed to cure the persistent HEV infection, highlighting the need of therapeutic options for HEV-infected immunosuppressed patients.

A Snapshot of Global Oncology Programming at US Cancer Centers: Results of the 2018 US NCI/ASCO NCI-Designated Cancer Center Global Oncology Survey

Background: The US National Cancer Institute (NCI) Center for Global Health (CGH) serves as a clearinghouse of information on global oncology activities within the NCI and across the 70 NCI-designated Cancer Centers. Global oncology, as defined by the American Society of Clinical Oncology (ASCO), “addresses disparities and differences in cancer prevention, care, research, education and the disease's social and human impact around the world”. While CGH routinely reports on NCI-funded global oncology projects conducted at the cancer centers, there is limited reporting of non-NCI funded global oncology activities of the cancer centers. To address this gap, CGH has surveyed the cancer centers about their global oncology programs and projects informally in 2012 and 2014. The 2018 survey, in partnership with ASCO, represents the first systematically conducted survey, with new questions about cancer center global oncology programs, faculty, and trainees. Aim: The aim of the 2018 survey is to develop a summary report of cancer center global oncology programs for use by cancer centers as a knowledge sharing and collaborative tool; by the NCI to inform program development; and, by ASCO to better understand the current state of global oncology training at US institutions. Methods: CGH developed a 2-part online survey with questions about global oncology projects led by cancer centers, and the level of support for global oncology training and faculty engagement at cancer centers. CGH piloted the survey to 7 of the 70 cancer centers (10%) from January to March 2018. Revisions based on the pilot were made, and CGH fielded the survey to the rest of the 63 cancer centers (90%) from March to July 2018. CGH supplemented the survey data with an Internet search of cancer centers' Web sites. The submitted data will be compiled, analyzed, and organized into a summary report for distribution to NCI, ASCO, and the cancer centers. Results: Data from the 7 pilot institutions show that while all 7 institutions (100%) have a global oncology program, there is great variance in the percentage of global oncology faculty who receive external or administrative research grant support for their work. Three institutions (43%) report that 50% or fewer global oncology faculty receive external research grant support, and 6 institutions (86%) report that 50% or fewer global oncology faculty receive cancer center administrative fund support for their work. Additional results and analysis will be available and presented as part of this presentation. Conclusion: In addition to serving as a knowledge sharing and collaboration tool for cancer centers, the global oncology survey allows NCI, ASCO, and global oncology partners to understand the current landscape of and sources of support for global oncology training, research, and programming at the cancer centers. This information will inform future discussions on how to strengthen global oncology programming and partnerships.

Net emergence of substitutions at position 28 in NS5A of hepatitis C virus genotype 4 in patients failing direct-acting antivirals detected by next-generation sequencing

More data on resistance of HCV genotype (GT) 3 and 4 to direct-acting antivirals (DAAs) are still needed. Here we investigated the presence of resistance-associated substitutions (RASs) pre- and post-treatment and their emergence under DAAs in HCV GT3- and GT4-infected patients failing DAA regimens by next-generation sequencing (NGS). Sanger sequencing and NGS were performed on NS5B and NS5A in plasma samples prior to and post treatment of 13 patients. Positions implicated in resistance to anti-NS5A and anti-NS5B in the literature were analysed. No baseline RASs was detected in NS5B but one GT4r virus developed the mutation S282T at failure. In NS5A, pre-existing RASs or polymorphisms were detected in viruses of 6/10 patients (L28M for a GT4a, M28V for a GT4r, L30R for a GT4a, 2 GT4d and 1 GT4r, and T58P for a GT4d) by Sanger sequencing and in viruses of 7/10 patients by NGS. Additional baseline minority substitutions detected by NGS were Y93H in a GT3a, L28M in a GT4a and GT4d, and L28F in a GT4d virus. At failure, these substitutions were found at a frequency of 100%. Y93H was detected alone at baseline, whilst L28M and L28F were accompanied by polymorphisms L30R or L30R + T58P. Use of NGS in patients failing DAAs and infected by HCV GT3 and GT4 revealed the emergence of specific patterns of substitutions in NS5A and NS5B, in particular substitutions at position 28 in NS5A in GT4 virus, highlighting the need to list these substitutions in guidelines for resistance interpretation.

Two Naturally Occurring Mutations on FVII Gene (S363I-W364C) Altering Intrinsic Catalytic Activity

Factor VII (FVII) requires the cleavage of an internal peptide bond and the association with tissue factor (TF) to attain its fully active FVIIa conformation. This event alone leaves FVIIa in a zymogen-like state of relatively low specific activity. The TF-induced allosteric enhancement of FVIIa’s activity contributes to the procoagulant activity of the complex. We have characterized two naturally occurring mutations (S363I W364C) on FVII gene. Both homozygous patients for each mutation have a normal FVII:Ag level associated to an undetectable FVII coagulant activity. The patient carrying the allele 364C had a more severe hemorrhagic diathesis than the S363I mutant. To understand the mechanism of these deficiency, in vitro expression analysis with further biochemical characterization of recombinant proteins of both mutants FVII-363I, FVII-364C and wild type (WTFVII) FVII constructs were done. The results recapitulated the patients’ plasma data with normal Ag level and no detectable coagulant activity. The D-F-Pip-R-pNA and CH3SO2-D-CHA-A-But-R chromogenic substrates were used to evaluate the amidolytic activity of WT and mutant FVII in presence and absence of recombinant tissue factor (rTF). Binding of FVII to rTF by a solid phase binding assay was done using recombinant human rTF. The results of amidolytic assays showed that rTF enhances 28 fold the value of the specificity of constant (kcat/Km) in WT but no activity was detectable in either mutant constructs under any condition. The equilibrium dissociation constant of rTF-FVIIa interaction showed Kd equal to 4.4 ± 0.2nM, 4.9 ± 0.5nM and 6 ± 0.9 of WT, 363I and 364C FVII forms, respectively. The Kd values of the non activated forms were equal to 24.7 ± 3.3, 24.4 ± 3.1 and 20.6 ± 4nM, respectively. These data demonstrate that, compared to the WT form, FVII-363I and FVII-364C have no significant affinity change for TF and that the detrimental effect of these two mutations is attributable to the loss of an efficient catalytic machinery in the FVII molecule causing a severe deficiency of coagulant activities.

A two adenine insertion polymorphism in the 3’ untranslated region of factor VII gene is associated with peripheral arterial disease but not with venous thrombosis

Polymorphic variants of genes encoding blood coagulation proteins have been extensively studied as risk factors for venous or arterial thrombosis A variation in the 3' untranslated region (UTR) involved in the post-transcriptional regulation of factor VII (FVII) gene has been recently identified, a two adenine insertion/deletion at nucleotide 11293. In this study, we investigated its effect on the risk of thrombosis in the frame of two case-control studies, including patients suffering from peripheral arterial disease (PAD) or venous thromboembolic (VTE) disease. The 3’UTR FVII gene polymorphism was investigated i) in 181 patients who had symptomatic atherosclerotic disease of the lower limbs, ii) in 178 patients who had had at least one episode of objectively diagnosed deep venous thrombosis and iii) in controls matched for age and sex. Plasma FVII antigen (FVII:Ag) levels were lower in the presence of the 3’UTR 2A insertion (68.4 ± 12.3%, 81.3 ± 14.5% and 89.5 ± 13.7% in 2A/2A, 2A/0 and 0/0 subjects respectively, p<0.0001). No significant relationship was found with VTE disease. In the contrary we observed a lower risk of PAD for the 2A/2A compared to the 0/0 genotype after adjustment for traditional risk factors (hypercholesterolemia, smoking status, diabetes and hypertension), with an OR of 0.24 [95% CI 0.06–0.99]. In conclusion, the 2 adenine insertion in the 3’UTR of FVII gene, related to lower plasma FVII levels, is a genetic variation that may contribute to reduce the risk of PAD.

Flexible and fragmentable tandem photosensitive nanocrystal skins

We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of single monolayers of colloidal water-soluble CdTe and CdHgTe nanocrystals (NCs) in adjacent junctions on a Kapton polymer tape. Owing to the usage of a single NC layer in each junction, noise generation was significantly reduced while keeping the resulting PNS films considerably transparent. In each junction, photogenerated excitons are dissociated at the interface of the semi-transparent Al electrode and the NC layer, with holes migrating to the contact electrode and electrons trapped in the NCs. As a result, the tandem PNSs lead to an open-circuit photovoltage buildup equal to the sum of those of the two single junctions, exhibiting a total voltage buildup of 128.4 mV at an excitation intensity of 75.8 μW cm(-2) at 350 nm. Furthermore, we showed that these flexible PNSs could be bent over 3.5 mm radius of curvature and cut out in arbitrary shapes without damaging the operation of individual parts and without introducing any significant loss in the total sensitivity. These findings indicate that the NC skins are promising as building blocks to make low-cost, flexible, large-area UV/visible sensing platforms with highly efficient full-spectrum conversion.

Clinical efficacy analysis of preoperative neoadjuvant chemotherapy with high-dose dense paclitaxel plus cisplatin in Stages IB2, IIA2, IIB cervical cancer in Iran

PURPOSE OF INVESTIGATION

In Iran, the authors use neoadjuvant chemotherapy (NACT) prior to surgery in cervical cancer due to limited access to the radiotherapy and very prolonged waiting time in accession to radiotherapy. The study was done to analyze the efficacy of the NACT with high dose-dense paclitaxel and cisplatin before radical surgery on cure rate, survival rate, and the progression of free survival rate of bulky tumor of cervical cancer in Stages 1B2, IId A2, and IIB.

MATERIALS AND METHODS

Fifty-two patients with cervical cancer in Stages Ib2, IIA2, and IIB were selected, and responding patients to chemotherapy were scheduled to undergo radical hysterectomy and bilateral pelvic lymphadenectomy with or without para-aortic lymphadenectomy.

RESULTS

Fifty out of 52 patients with a median age of 50 years were evaluable for clinical response. Thirty-two patients (64%) responded to the NACT including six (12%) with a complete clinical response. There was no statistical relationship between clinical response, tumor stage and size, and parametrical involvement, however, patients with higher grade of tumor, adenocarcinoma or tumor in upper 2/3 of vagina showed a higher probability of no response to chemotherapy. Downstaging after NACT in all stages was statistically significant regarding pathologic findings and clinical response (p = 0.002). Five-year survival was 88% and factors affecting survival and disease-free survival were pathological response and tumor site based on cox-regression analysis. Overall recurrence rate was 20% and tumor size was the only significant relevant factor for recurrence (p = 0.017).

CONCLUSION

Combined regimen of chemotherapy in locally advanced cervical cancer proved to be valuable and efficacious without any late complications.

Coexistence of circulating HBsAg and anti-HBs antibodies in chronic hepatitis B carriers is not a simple analytical artifact and does not influence HBsAg quantification

BACKGROUND

Presence at the same time of HBsAg and anti-HBs antibodies (HBsAg/Ab) is an entity sometimes encountered in chronic hepatitis B (CHB) carriers.

OBJECTIVES

This study was designed to characterize such serological profiles and to assess the reliability of serological marker quantification by three commercially available assays in this setting.

STUDY DESIGN

Among 2578 CHB identified patients, 129 (5%) had an HBsAg/Ab profile as determined by Abbott Architect. After exclusion of co-infections (HIV, HCV, HDV), HBV reactivation or HBIg treatment, 101 samples from 62 patients were tested for HBsAg and anti-HBs quantification using Architect, DiaSorin Liaison-XL and Roche Modular-Cobas. Influence of genotype and HBsAg variants was studied in 31 samples with HBV replication.

RESULTS

HBsAg detection was confirmed with the 3 techniques for 98% (n = 99) of the samples while the HBsAg/Ab profile was concordant between all techniques for 65% of them. The overall correlation between the 3 HBsAg quantification techniques was good (R(2): 0.94-0.97). The median HBsAg concentration was comparable for the 99 samples whatever the used technique but a bias of -0.11 and 0.02 log IU/mL were noticed for DiaSorin and Roche compared to Abbott, respectively. Anti-HBs quantifications were poorly correlated between techniques with major discrepancies observed. Genotype and substitutions within the "a" determinant showed an impact on HBsAg quantification.

CONCLUSIONS

The double HBsAg/Ab profile is not an analytical artifact and is confirmed on all commercially available techniques. While such profile does not influence HBsAg quantification, differences of HBsAg quantification were noticed according to HBV genotype or HBsAg variant.

A new technique for the strengthening of aluminum tungsten inert gas weld metals: using carbon nanotube/aluminum composite as a filler metal

The effect of multi-walled carbon nanotube (MWCNT) on the mechanical properties of aluminum multipass weld metal prepared by the tungsten inert gas (TIG) welding process was investigated. High energy ball milling was used to disperse MWCNT in the aluminum powder. Carbon nanotube/aluminum composite filler metal was fabricated for the first time by hot extrusion of ball-milled powders. After welding, the tensile strength, microhardness and MWCNT distribution in the weld metal were investigated. The test results showed that the tensile strength and microhardness of weld metal was greatly increased when using the filler metal containing 1.5 wt.% MWCNT. Therefore, according to the results presented in this paper, it can be concluded that the filler metal containing MWCNT can serve as a super filler metal to improve the mechanical properties of TIG welds of Al and its alloys.

[Viral markers of hepatitis B, C and D and HB vaccination status of a health care team in a rural district of Cameroon]

Ninety-three health care workers (HCW) in the Tokombere sahelian district volunteered to participate in a trial to investigate viral markers of hepatitis B, C, and D and HB vaccination status.

METHODS

. Sera were tested using the Vikia HBsAg kit followed by CMIA for detection of HBsAg, anti-HBs, anti-HBc, and anti-HCV. HBsAg-positive HCW were tested for HBV-DNA, anti-HDV, and, if positive for anti-HDV, HDV-RNA.

RESULTS

Analysis of anti-HBc positivity indicated that 91% of HCW had been infected by HBV, regardless of vaccination history. Vikia HBsAg results were confirmed by chemiluminescent microparticle immunoassay (CMIA) in all HCW and were positive in 17 HCW with virus load >2000 IU/mL in 6 and HDV co-infection in 6. Anti-HCV was found in 6 HCW. Among the 55 HCW that had not been vaccinated, only 3 needed vaccination because of anti-HBc negativity. Among HCW considered for HBV treatment, one patient presenting HBV/HDV co-infection was excluded after diagnosis of hepatocarcinoma.

CONCLUSION

Systematic HB vaccination of new HCW appears unnecessary in this rural region of Africa. Anti-HBc screening is cost-effective for identifying HCW requiring vaccination. Vikia HBsAg is effective for point-of-care screening. We underline the need for universal early (preferably neonatal) HB vaccination and for availability of anti-HBV drug in limited-resource countries.

Performance of the DiaSorin LIAISON(®) anti-HBs II for the detection of hepatitis B surface antibodies: comparison with the Abbott Architect anti-HBs assay

BACKGROUND

Detection of hepatitis B virus (HBV) surface antibodies (anti-HBs) is required in order to evaluate the response to hepatitis B vaccination and to optimize post-exposure monitoring. The widespread use of vaccines has highlighted the need for accurate and consistent quantification, yielding comparable quantitative results.

OBJECTIVES

This study assessed the adequacy of DiaSorin LIAISON(®) anti-HBs II assay in detecting anti-HBs antibodies and determined the correlation with Abbott Architect anti-HBs quantification.

STUDY DESIGN

Anti-HBs levels were measured in parallel using Abbott and DiaSorin kits on WHO international standard dilutions and 350 routine samples pre-screened with Abbott Architect anti-HBs. Three different serological panels were tested: vaccinated subjects (n=121); subjects with past HBV infection (n=109); and subjects with no HBV infection marker (n=69). Serial dilutions from nine high-titer anti-HBs samples were used to address linearity.

RESULTS

Anti-HBs concentration measured on WHO standard dilutions indicated a good calibration of DiaSorin values against international units, while results for Abbott were below those expected. A strong impact of the dilution matrix used was observed when performing dilutions on high-titer samples. Despite difference in absolute quantification, the overall clinical agreement between the two assays was 96.9%, with strong correlation (r=0.92) between concentrations and good linearity over the quantification range.

CONCLUSIONS

The DiaSorin LIAISON(®) anti-HBs II assay shows excellent standardization to the WHO standard and good linearity. The assay is suitable for current clinical laboratory practice.

Is postoperative CA125 level in patients with epithelial ovarian cancer reliable to guess the optimality of surgery?

INTRODUCTION

Cytoreductive surgery is a pivotal component of primary treatment in patients with ovarian epithelial caner (OEC) and several studies have shown better outcomes of optimal debulking. The aim of this prospective study was to determine if optimum versus suboptimal cytoreductive surgery predicts CA125 levels two weeks after surgery.

MATERIAL AND METHODS

Sixty patients with epithelial ovarian cancer scheduled for cytoreductive surgery in Imam Khomeini Hospital, Tehran, Iran were enrolled in this study. Two groups of patients were to undergo optimal or suboptimal cytoreductive surgery. Optimal cytoreduction was defined as the largest volume of residual disease < 1 cm in maximal dimension. CA125 levels were measured in all patients preoperatively and at two, seven and 14 days after surgery. CA125 levels were converted to a log scale.

RESULTS

The distribution of staging, grading and types of tumors in each group were statistically equal but insignificant (chi square). The difference in mean of CA125 before and two weeks after surgery was statistically significant (paired t-test; p = 0.0001) but the grade, stage and type of tumors did not have any impact on CA125 regression. However, regression of CA125 two weeks after the operation did not differ statistically between the optimal and suboptimal cytoreduction groups (repeated measure ANOVA).

CONCLUSION

Although, postoperative CA125 decreased significantly in two weeks after tumor cytoreduction in patients with epithelial ovarian cancer, its regression did not differ according to optimal or suboptimal groups.

Natural variability of NS3 protease in patients infected with genotype 4 hepatitis C virus (HCV): implications for antiviral treatment using specifically targeted antiviral therapy for HCV

To analyze the genetic diversity of the NS3 gene in patients infected with hepatitis C virus (HCV) genotype 4 (HCV-4) and to assess the possible effects of the gene polymorphism (or variability) on drug susceptibility, 43 NS3 gene sequences were determined for 53 selected patients with HCV-4 infection. NS3 sequencing, like NS5B sequencing, allowed correct subtype determination. Most residues that were located within the catalytic triad or the NS4-binding region or that were involved in metal binding were highly conserved and identical to those found in HCV genotype 1. Compared with HCV genotype 1, all HCV-4 NS3 protein presented V36L and C16T residue changes that could potentially reduce antiprotease activity. The efficacy of antiprotease in HCV-4-infected patients remains to be proven in large clinical trials.

Impact of hepatitis B virus genotypes and surface antigen variants on the performance of HBV real time PCR quantification

Quantitative PCR assays used to monitor hepatitis B virus (HBV) load differ in their ability to detect different HBV variants. This study evaluated the performance of the Abbott RT PCR assay for quantitating DNA from different HBV genotypes and from HBV variants bearing HBsAg gene mutations. The study was performed on a randomly-selected sample with a viral load >6logIU/mL for each genotype and on 25 HBsAg variants. Each sample was assayed using the Abbott RT assay and with the Roche Cobas AmpliPrep-Cobas TaqMan as a reference method. All HBV genotypes were detected with the Abbott RT assay with an equivalent dynamic range (1-8logIU/mL). For each genotype, the data suggest that the assay was linear over the entire dilution range (r(2): 0.985-0.995). For the 25 HBsAg variants, viral titres determined with the two assays correlated well (r(2): 0.929). The mean difference between the two methods was -0.295 (95% CI: -0.520 to -0.071). The difference was lower than 1log unit in all but two cases. In conclusion, the Abbott RT assay can detect and quantify DNA from different HBV variants with equivalent performance and is thus suitable for routine monitoring of patients with chronic HBV infections.

A two adenine insertion polymorphism in the 3' untranslated region of factor VII gene is associated with peripheral arterial disease but not with venous thrombosis. Results of case-control studies

Polymorphic variants of genes encoding blood coagulation proteins have been extensively studied as risk factors for venous or arterial thrombosis A variation in the 3' untranslated region (UTR) involved in the post-transcriptional regulation of factor VII (FVII) gene has been recently identified, a two adenine insertion/deletion at nucleotide 11293. In this study, we investigated its effect on the risk of thrombosis in the frame of two case-control studies, including patients suffering from peripheral arterial disease (PAD) or venous thromboembolic (VTE) disease. The 3'UTR FVII gene polymorphism was investigated i) in 181 patients who had symptomatic atherosclerotic disease of the lower limbs, ii) in 178 patients who had had at least one episode of objectively diagnosed deep venous thrombosis and iii) in controls matched for age and sex. Plasma FVII antigen (FVII: Ag) levels were lower in the presence of the 3'UTR 2A insertion (68.4 +/- 12.3%, 81.3 +/- 14.5% and 89.5 +/- 13.7% in 2A/2A, 2A/0 and 0/0 subjects respectively, p < 0.0001). No significant relationship was found with VTE disease. In the contrary we observed a lower risk of PAD for the 2A/2A compared to the 0/0 genotype after adjustment for traditional risk factors (hypercholesterolemia, smoking status, diabetes and hypertension), with an OR of 0.24 [95% CI 0.06-0.99]. In conclusion, the 2 adenine insertion in the 3'UTR of FVII gene, related to lower plasma FVII levels, is a genetic variation that may contribute to reduce the risk of PAD.

Recurrence of a Phe31Ser mutation in the Gla domain of blood coagulation factor X, in unrelated Algerian families: a founder effect?

The presence of gene lesions in blood coagulation factor X (FX) was investigated in eight FX-deficient patients with severe bleeding symptoms, originating from five unrelated Algerian families (FX coagulant activity <1%, FX antigen ranging from 2% to 16%). A missense mutation (p.Phe31Ser) in the Gla domain was found in homozygous form for all patients but one, who is a compound heterozygote for the Phe31Ser mutation and for a non-sense mutation, Tyr130Term in EGF-2 domain. The haplotypes of FX alleles were determined by the following allelic variants located in the promoter: g.1323_1330delTTGTGA (A1/A2), g.1449T>C, g.1451C>A, upstream to exon 3: g.17257C>T and downstream to exon 3: g.17396A>C. The A1-C-A-T-C haplotype was found on each allele bearing the Phe31Ser mutation in the eight FX deficient patients contrasting with its low frequency (8%) in a control Algerian population (in which the Phe31Ser substitution was absent). The patients came from the same geographical area of Algeria (5/8 are certainly from Kabyle origin) and the haplotype analysis suggests a founder effect. Transient expression study reveals that, for the mutant FX-Phe31Ser, FX antigen level was 60% in conditioned media and 140% in cell lysates compared with the wild type FX. The partial retention and intracellular accumulation of the mutant FX might be due to impaired folding and/or conformational changes, and the discrepancies observed between the FX antigen level in COS-7 cell supernatant (60%) and in the patients plasma (2-16%) to an in vivo increased clearance of the secreted unstable FX mutant.

The natural mutation by deletion of Lys9 in the thrombin A-chain affects the pKa value of catalytic residues, the overall enzyme's stability and conformational transitions linked to Na+ binding

The catalytic competence of the natural thrombin mutant with deletion of the Lys9 residue in the A-chain (deltaK9) was found to be severely impaired, most likely due to modification of the 60-loop conformation and catalytic triad geometry, as supported by long molecular dynamics (MD) simulations in explicit water solvent. In this study, the pH dependence of the catalytic activity and binding of the low-molecular mass inhibitor N-alpha-(2-naphthylsulfonyl-glycyl)-4-amidinophenylalanine-piperidine (alpha-NAPAP) to the wild-type (WT) and deltaK9 thrombin forms were investigated, along with their overall structural stabilities and conformational properties. Two ionizable groups were found to similarly affect the activity of both thrombins. The pKa value of the first ionizable group, assigned to the catalytic His57 residue, was found to be 7.5 and 6.9 in ligand-free deltaK9 and WT thrombin, respectively. Urea-induced denaturation studies showed higher instability of the deltaK9 mutant compared with WT thrombin, and disulfide scrambling experiments proved weakening of the interchain interactions, causing faster release of the reduced A-chain in the mutant enzyme. The sodium ion binding affinity was not significantly perturbed by Lys9 deletion, although the linked increase in intrinsic fluorescence was lower in the mutant. Essential dynamics (ED) analysis highlighted different conformational properties of the two thrombins in agreement with the experimental conformational stability data. Globally, these findings enhanced our understanding of the perturbations triggered by Lys9 deletion, which reduces the overall stability of the molecule, weakens the A-B interchain interactions, and allosterically perturbs the geometry and protonation state of catalytic residues of the enzyme.

A critical role for Gly25 in the B chain of human thrombin

We have recently identified (Akhavan S et al., Thromb Haemost 2000; 84: 989-97) a patient with a mild bleeding diathesis associated to an homozygous mutation in the thrombin B chain (Gly25Ser, chymotrypsinogen numbering, i.e. position 330 in human prothrombin numbering). Transient transfection of wild-type prothrombin (FII-WT) and mutant prothrombin (designated FII-G25(330)S) cDNA in COS-7 cells showed a mild reduction (50%) in FII-G25(330)S production. Recombinant proteins, stably expressed in Chinese hamster ovary cells, were isolated and activated by Taipan snake or Echis carinatus venoms. We show that the G25(330)S mutation results in a decrease in the rate of prothrombin proteolytic activation. The mutation also significantly decreases (i) the catalytic activity of thrombin with a 9-fold reduction in catalytic efficiency of the mutant toward S-2238; (ii) the interaction with benzamidine; (iii) the rate of inhibition by TLCK and antithrombin; and (iv) the rate of hydrolysis of macromolecular substrates (fibrinogen, protein C). In contrast, exosite I does not appear to be affected by the molecular defect. These results, together with molecular modeling and dynamics, indicate that Gly25(330) is important for proper expression and probably proper folding of prothrombin, and also plays a critical role in both the alignment of the catalytic triad and the flexibility of one of the activation segments of prothrombin.

The P303T mutation in the human factor VII (FVII) gene alters the conformational state of the enzyme and causes a severe functional deficiency

We report the results of in vitro expression and biochemical characterization of the naturally occurring type II mutation Pro303Thr (P303T) in the factor VII (FVII) gene. Recombinant activated mutated FVII (FVIIa303T), compared with the activated wild-type FVII (FVIIaWT), showed reduced amidase activity toward synthetic substrates, especially when the observed reduced binding affinity for human soluble tissue factor (TF) (K(d) from 4.4 nmol/l for FVIIaWT to 17.3 nmol/l for FVIIa303T) was overcome by a fully saturating TF concentration. Likewise, factor X (FX) hydrolysis by FVIIa303T showed a reduced activity in the absence (and more severely in the presence) of TF (k(cat)/K(m) from 2.3 x 10(7)/mol/l s for FVIIaWT to 8.7 x 10(5)/mol/l s for FVIIa303T). These results showed that the mutant FVIIa is more shifted toward a zymogen-like form compared to FVIIaWT, suggesting that P303 facilitates the conformational transitions that stabilize the active form of FVIIa. The alteration of these allosteric equilibria is especially evident in the presence of TF, which was unable to shift the equilibrium toward a fully active FVIIa form. Additional experiments showed that both TF-catalysed FVII303T autoactivation and FVII303T activation by activated FX in the presence of TF were severely impaired, mainly because of an increase of the K(m) value. Altogether, these defects may explain the severe bleeding symptoms in a patient carrying the FVIIP303T mutation.

A Natural Prothrombin Mutant Reveals an Unexpected Influence of A-chain Structure on the Activity of Human α-Thrombin

We have recently identified in two unrelated patients with bleeding tendency a homozygous mutation causing a deletion of one of the two contiguous Lys(9)/Lys(10) residues in the A-chain of alpha-thrombin (DeltaK9). We used in vitro expression analysis to clarify the role of the deletion of Lys(9) or Lys(10) in the thrombin function. The k(cat)/K(m) value of the hydrolysis by DeltaK9 of the synthetic substrate Phe-Pip-Arg-p-nitroanilide (where Pip represents l-pipecolyl) and fibrinopeptide A was 18- and 60-fold lower, respectively, compared with wild type (WT). Interaction with antithrombin was also reduced in the mutant, the association rate being about 20-fold lower than in the WT thrombin. The sensitivity to sodium ion of DeltaK9 was found significantly attenuated compared with the WT form. DeltaK9 has a very weak platelet-activating capacity, attributed to a severely defective PAR1 interaction, whereas the binding to the platelet glycoprotein Ibalpha was unaffected. Likewise, the interaction with protein C was severely impaired, whereas interaction with thrombomodulin had a normal K(d) value. At variance with these findings, both low affinity (basic pancreatic trypsin inhibitor) and high affinity (N-alpha-[2-naphthylsulfonyl-glycyl]-4-amidinophenylalanine-piperidide) thrombin inhibitors displayed a better binding to DeltaK9 than to the WT form, indicating a better accommodation of these inhibitors into the catalytic pocket of DeltaK9. A molecular dynamics simulation of the DeltaK9 thrombin in full explicit water solvent provided support to the role of the A-chain in affecting conformation and catalytic properties of the B-chain, especially in some insertion loops of the enzyme, such as the 60-loop, as well as in the geometry of the catalytic triad residues.

Phenotypic and genetic analysis of a compound heterozygote for dys- and hypoprothrombinaemia

We studied a 2-year-old boy with a phenotype of combined hypo- and dysprothrombinaemia. Sequencing of polymerase-chain-reaction-amplified genomic DNA revealed three different mutations in heterozygosity, a G to A transition at position 7312, resulting in the replacement of arginine 271 by histidine, an A to G transition at position 20058, resulting in the replacement of histidine 562 by arginine, and a 2-bp deletion at 20062-20063, causing a frameshift and a premature stop codon in exon 14. The first two mutations are compatible with the dysprothrombinaemia phenotype, whereas the small deletion is thought to be the cause of hypoprothrombinaemia.

Two naturally occurring mutations on FVII gene (S363I-W364C) altering intrinsic catalytic activity

Factor VII (FVII) requires the cleavage of an internal peptide bond and the association with tissue factor (TF) to attain its fully active FVIIa conformation. This event alone leaves FVIIa in a zymogen-like state of relatively low specific activity. The TF-induced allosteric enhancement of FVIIa's activity contributes to the procoagulant activity of the complex. We have characterized two naturally occurring mutations (S363I - W364C) on FVII gene. Both homozygous patients for each mutation have a normal FVII: Ag level associated to an undetectable FVII coagulant activity. The patient carrying the allele 364C had a more severe hemorrhagic diathesis than the S363I mutant. To understand the mechanism of these deficiency, in vitro expression analysis with further biochemical characterization of recombinant proteins of both mutants FVII-363I, FVII-364C and wild type (WTFVII) FVII constructs were done. The results recapitulated the patients' plasma data with normal Ag level and no detectable coagulant activity. The D-F-Pip-R-pNA and CH(3)SO(2)-D-CHA-A-But-R chromogenic substrates were used to evaluate the amidolytic activity of WT and mutant FVII in presence and absence of recombinant tissue factor (rTF). Binding of FVII to rTF by a solid phase binding assay was done using recombinant human rTF. The results of amidolytic assays showed that rTF enhances 28 fold the value of the specificity of constant (kcat/K(m)) in WT but no activity was detectable in either mutant constructs under any condition. The equilibrium dissociation constant of rTF-FVIIa interaction showed Kd equal to 4.4 +/- 0.2nM, 4.9 +/- 0.5nM and 6 +/- 0.9 of WT, 363I and 364C FVII forms, respectively. The K(d) values of the non activated forms were equal to 24.7 +/- 3.3, 24.4 +/- 3.1 and 20.6 +/- 4nM, respectively. These data demonstrate that, compared to the WT form, FVII-363I and FVII-364C have no significant affinity change for TF and that the detrimental effect of these two mutations is attributable to the loss of an efficient catalytic machinery in the FVII molecule causing a severe deficiency of coagulant activities.

Molecular and functional characterization of a natural homozygous Arg67His mutation in the prothrombin gene of a patient with a severe procoagulant defect contrasting with a mild hemorrhagic phenotype

In a patient who presented with a severe coagulation deficiency in plasma contrasting with a very mild hemorrhagic diathesis a homozygous Arg67His mutation was identified in the prothrombin gene. Wild-type (factor IIa [FIIa]-WT) and mutant Arg67His thrombin (FIIa-MT67) had similar amidolytic activity. By contrast, the k(cat)/K(m) value of fibrinopeptide A hydrolysis by FIIa-WT and FIIa-MT67 was equal to 2.1 x 10(7) M(-1)s(-1) and 9 x 10(5) M(-1)s(-1). Decreased activation of protein C (PC) correlated with the 33-fold decreased binding affinity for thrombomodulin (TM; K(d) = 65.3 nM vs 2.1 nM, in FIIa-MT67 and in FIIa-WT, respectively). In contrast, hydrolysis of PC in the absence of TM was normal. The Arg67His mutation had a dramatic effect on the cleavage of protease-activated G protein-coupled receptor 1 (PAR-1) 38-60 peptide (k(cat/)K(m) = 4 x 10(7) M(-1)s(-1) to 1.2 x 10(6) M(-1)s(-1)). FIIa-MT67 showed a weaker platelet activating capacity, attributed to a defective PAR-1 interaction, whereas the interaction with glycoprotein Ib was normal. A drastic decrease (up to 500-fold) of the second-order rate constant pertaining to heparin cofactor II (HCII) interaction, especially in the presence of dermatan sulfate, was found for the FIIa-MT67 compared with FIIa-WT, suggesting a severe impairment of thrombin inhibition by HCII in vivo. Finally, the Arg67His mutation was associated with a 5-fold decrease of prothrombin activation by the factor Xa-factor Va complex, perhaps through impairment of the prothrombin-factor Va interaction. These experiments show that the Arg67His substitution affects drastically both the procoagulant and the anticoagulant functions of thrombin as well as its inhibition by HCII. The mild hemorrhagic phenotype might be explained by abnormalities that ultimately counterbalance each other.

Gene mutations and three-dimensional structural analysis in 13 families with severe factor X deficiency

Factor X (FX) deficiency is a rare autosomal recessive disorder. The phenotype and genotype of 15 Iranian patients with FX deficiency from 13 unrelated families with a high frequency of consanguinity were analysed. Five different assays identified four patients from three families with a discrepancy between low-FX coagulant activity (FX:C) and higher-FX antigen (FX:Ag) (a type II deficiency). The remaining 11 patients had parallel reductions of FX:C and FX:Ag (a type I deficiency). Nine different homozygous candidate mutations were identified, of which eight were novel. The four type II cases were associated with an Arg(-1)Thr missense mutation in the prepropeptide: Arg(-1) is highly conserved in all vitamin K-dependent proteins. Four type I mutations (Gly78Asp, Cys81Tyr, Gly94Arg and Asp95Glu) were localized to the EGF-1 and EGF-2 domains, for which molecular views showed that the protein folding would be disrupted. The type I mutation Gly222Asp was localized in the catalytic domain of FX, and is sufficiently close to the Asp-His-Ser catalytic triad to disrupt its correct protein folding. The two type I splice site mutations were IVS1+3, A-->T and IVS2-3, T-->G. These novel homozygous FX mutations were consistent with their phenotypes and agree with experimental data from knockout mice, indicating that FX is an essential protein for survival.

Rare coagulation deficiencies

Deficiencies of coagulation factors (other than factor VIII and factor IX) that cause a bleeding disorder are inherited as autosomal recessive traits and are generally rare, with prevalences in the general population varying between 1 : 500 000 and 1 : 2 000 000. In the last few years, the number of patients with recessively transmitted coagulation deficiencies has increased in European countries with a high rate of immigration of Islamic populations, because in these populations, consanguineous marriages are frequent. Owing to the relative rarity of these deficiencies, the type and severity of bleeding symptoms, the underlying molecular defects and the actual management of bleeding episodes are not as well established as for haemophilia A and B. This article reviews these disorders in terms of their clinical manifestations and characterization of the molecular defects involved. The general principles of management are also discussed.

KEYWORDS

afibrinogenaemia, autosomal recessive disorders, factor VIII, factor XI, factor XIII.

Identification and three-dimensional structural analysis of nine novel mutations in patients with prothrombin deficiency

Prothrombin deficiency is an autosomal recessive disorder associated with a moderately severe bleeding tendency. In this study, 13 patients with prothrombin deficiency were screened for the presence of alterations in the prothrombin gene, and nine novel candidate mutations were identified. Of 11 patients with hypoprothrombinemia, ten are homozygous for five mutations and one patient is a compound heterozygote. The two patients with dysprothrombinemia are homozygous for two mutations. Eight of nine mutations are missense ones associated with single amino acid substitutions in the propeptide (Arg-1Gln, Arg-2Trp), the kringle-1 (Asp118Try) and kringle-2 (Arg220Cys) domains and the catalytic serine protease domain (Gly330Ser, Ser354Arg. Arg382His and Arg538Cys). The ninth mutation is an in-frame deletion of 3 bp that results in the omission of one amino acid (del Lys 301/302). The combination of these missense mutations with crystal structures for alpha-thrombin and the prothrombin fragments 1 and 2 resulted in new insight into the function of alpha-thrombin. The hypoprothrombinemia mutations were inferred to affect either the cleavage of the propeptide from the Gla domain, the stability of the kringle-1 and -2 domains, or the close association of the A and B chains of the serine protease domain. The dysprothrombinemia mutations were inferred to directly affect catalytic function through their location at the active site crevice or exosite 1 within the serine protease domain.

A novel polymorphism in intron 1a of the human factor VII gene (G73A): study of a healthy Italian population and of 190 young survivors of myocardial infarction

We have identified a novel polymorphism located in intron 1a of the human factor VII gene, caused by the nucleotide change G to A at position + 73. In a population of 128 healthy individuals from northern Italy, the variant A73 allele had a frequency of 0.21, whereas the frequency of the previously reported 10 bp insertion allele located at -323 in the promoter region was 0.17 and that of the Q353 allele in the catalytic region of the factor VII gene was 0. 20. In 75% of the healthy individuals, the A73 allele was present together with the 10 bp insertion and the Q353 alleles, indicating a strong linkage disequilibrium. The concomitant presence of A73 with both the 10 bp and the Q353 alleles was associated with the lowest factor VII levels, measured as coagulant activity, activated factor VII and factor VII antigen. The G73A polymorphism was also evaluated in 190 survivors of myocardial infarction who had experienced the event before the age of 45 years and in 179 individuals with a negative exercise test matched with patients for sex, age and geographical origin. Patients carrying the A73 allele associated with lower factor VII levels tended to have a lower risk of myocardial infarction (adjusted odds ratio 0.54; 95% confidence intervals 0.29-0.99). In conclusion, we found a novel variant allele in intron 1a of the human factor VII gene that is often associated in healthy individuals with the 10 bp and Q353 alleles in the promoter and catalytic region of the same gene. This intronic mutation, alone or in association with other factor VII gene polymorphisms, might confer protection against myocardial infarction in the young.

Identification and Three-dimensional Structural Analysis of Nine Novel Mutations in Patients with Prothrombin Deficiency

Prothrombin deficiency is an autosomal recessive disorder associated with a moderately severe bleeding tendency. In this study, 13 patients with prothrombin deficiency were screened for the presence of alterations in the prothrombin gene, and nine novel candidate mutations were identified. Of 11 patients with hypoprothrombinemia, ten are homozygous for five mutations and one patient is a compound heterozygote. The two patients with dysprothrombinemia are homozygous for two mutations. Eight of nine mutations are missense ones associated with single amino acid substitutions in the propeptide (Arg-1Gln, Arg-2Trp), the kringle-1 (Asp118Try) and kringle-2 (Arg220Cys) domains and the catalytic serine protease domain (Gly330Ser, Ser354Arg, Arg382His and Arg538Cys). The ninth mutation is an in-frame deletion of 3 bp that results in the omission of one amino acid (del Lys 301/302). The combination of these missense mutations with crystal structures for α-thrombin and the prothrombin fragments 1 and 2 resulted in new insight into the function of α-thrombin. The hypoprothrombinemia mutations were inferred to affect either the cleavage of the propeptide from the Gla domain, the stability of the kringle-1 and −2 domains, or the close association of the A and B chains of the serine protease domain. The dysprothrombinemia mutations were inferred to directly affect catalytic function through their location at the active site crevice or exosite 1 within the serine protease domain.

Gly319 --> arg substitution in the dysfunctional prothrombin Segovia

The molecular defect of a congenitally dysfunctional form of prothrombin, prothrombin Segovia, was identified in a patient with a severe bleeding tendency, reduced prothrombin coagulant activity, and normal antigen level. Nucleotide sequencing of amplified DNA revealed a G --> A change at nucleotide 7539 of exon 9 of the prothrombin gene. This resulted in the substitution of Gly319 by Arg. The proband was homozygous for this mutation, his father and brother were heterozygous. We surmised that the substitution, which occurs near the site of cleavage of prothrombin by factor Xa (Arg320-Ile321), altered the conformation of the protein making the cleavage site inaccessible.

Interaction between the G20210A mutation of the prothrombin gene and oral contraceptive use in deep vein thrombosis

Single-point mutations in the gene coding for prothrombin (factor II:A20210) or factor V (factor V:A1691) are associated with an increased risk of venous thromboembolism. The use of oral contraceptives is also a strong and independent risk factor for the disease, and the interaction between factor V:A1691 and oral contraceptives greatly increases the risk. No information is available about the interaction between oral contraceptives and mutant prothrombin. We investigated 148 women with a first, objectively confirmed episode of deep vein thrombosis and 277 healthy women as controls. Fourteen patients (9.4%) were carriers of factor II:A20210, 24 (16.2%) of factor V:A1691, and 4 (2.7%) of both defects. Among controls, the prevalence was 2.5% for either factor II:A20210 or factor V:A1691, and there was no carrier of both the mutations. The relative risk of thrombosis was 6-fold for factor II:A20210 and 9-fold for factor V:A1691. The most prevalent circumstantial risk factor in patients and the only one observed in controls was oral contraceptive use, which per se conferred a 6-fold increased risk of thrombosis. The risk increased to 16.3 and 20.0 when women with factor II:A20210 or factor V:A1691 who used oral contraceptives were compared with noncarriers and nonusers. These figures indicate a multiplicative interaction between the genetic risk factors and oral contraceptives. No difference in the type of oral contraceptives was observed between patients and controls, those of third generation being the most frequently used (73% and 80%). We conclude that carriers of the prothrombin mutation who use oral contraceptives have a markedly increased risk of deep vein thrombosis, much higher than the risk conferred by either factor alone.

Laboratory screening of thrombophilia. Evaluation of the diagnostic efficacy of a global test to detect congenital deficiencies of the protein C anticoagulant pathway

Clinical laboratories are at present confronted with increasing demands for thrombophilia work-up, which may seriously overwhelm their capacity. Recently, methods able to investigate the protein C anticoagulant pathway globally have been proposed. In this study we investigated the reliability of one such method for its ability to detect patients with known defects of the pathway by testing plasmas from patients with the FVQ506 mutation, with congenital protein C, protein S or antithrombin deficiencies, and patients with previous history of thrombosis, but no identifiable defects. The results show that the new global test fulfils the requirements for congenital protein C deficiency and activated protein C resistance associated with the FVQ506 mutation, which account for more than half of the congenital defects found in thrombophilia. However, congenital protein S deficiency very often remains undetected by this test. Improvement of sensitivity toward this component of the protein C anticoagulant pathway would enroll the global test as a suitable candidate to explore the pathway. Since antithrombin, which also remains undetected by this test, is an additional important risk factor for venous thrombosis, devoting time and effort to developing global tests able to detect defects in both the antithrombin and protein C pathways is warranted.

Suicidality and cognitive vulnerability to depression among college students: a prospective study

Using a behavioral high-risk two-site prospective design, we tested the cognitive vulnerability hypotheses about suicidality. Consistent with prediction, the high cognitive risk (HR) participants were more likely than the low cognitive risk (LR) participants to exhibit suicidality, measured by both structured diagnostic interview and questionnaire self-report, during the 2 1/2 year prospective follow-up period. Moreover, when the prospective period was examined as a whole, the mediation hypothesis derived from the cognitive theories was strongly supported. Hopelessness appeared to mediate the obtained relationship between cognitive vulnerability and suicidality. Finally, the obtained relationship between cognitive vulnerability and suicidality was not mediated by other hypothesized risk factors for suicidality not specified in the cognitive theories, such as past suicidality, personal history of depressive disorders, borderline and antisocial personality dysfunction, and parental history of depression.