Resistance to white spot syndrome virus in the European shore crab is associated with suppressed virion trafficking and heightened immune responses

Introduction

All decapod crustaceans are considered potentially susceptible to White Spot Syndrome Virus (WSSV) infection, but the degree of White Spot Disease (WSD) susceptibility varies widely between species. The European shore crab Carcinus maenas can be infected with the virus for long periods of time without signs of disease. Given the high mortality rate of susceptible species, the differential susceptibility of these resistant hosts offers an opportunity to investigate mechanisms of disease resistance.

Methods

Here, the temporal transcriptional responses (mRNA and miRNA) of C. maenas following WSSV injection were analysed and compared to a previously published dataset for the highly WSSV susceptible Penaeus vannamei to identify key genes, processes and pathways contributing to increased WSD resistance.

Results

We show that, in contrast to P. vannamei, the transcriptional response during the first 2 days following WSSV injection in C. maenas is limited. During the later time points (7 days onwards), two groups of crabs were identified, a recalcitrant group where no replication of the virus occurred, and a group where significant viral replication occurred, with the transcriptional profiles of the latter group resembling those of WSSV-susceptible species. We identify key differences in the molecular responses of these groups to WSSV injection.

Discussion

We propose that increased WSD resistance in C. maenas may result from impaired WSSV endocytosis due to the inhibition of internal vesicle budding by dynamin-1, and a delay in movement to the nucleus caused by the downregulation of cytoskeletal transcripts required for WSSV cytoskeleton docking, during early stages of the infection. This response allows resistant hosts greater time to fine-tune immune responses associated with miRNA expression, apoptosis and the melanisation cascade to defend against, and clear, invading WSSV. These findings suggest that the initial stages of infection are key to resistance to WSSV in the crab and highlight possible pathways that could be targeted in farmed crustacean to enhance resistance to WSD.

Molecular mechanisms of embryonic tail development in the self-fertilizing mangrove killifish Kryptolebias marmoratus

Using the self-fertilizing mangrove killifish, we characterized two mutants, shorttail (stl) and balltail (btl). These mutants showed abnormalities in the posterior notochord and muscle development. Taking advantage of a highly inbred isogenic strain of the species, we rapidly identified the mutated genes, noto and msgn1 in the stl and btl mutants, respectively, using a single lane of RNA sequencing without the need of a reference genome or genetic mapping techniques. Next, we confirmed a conserved morphant phenotype in medaka and demonstrate a crucial role of noto and msgn1 in cell sorting between the axial and paraxial part of the tail mesoderm. This novel system could substantially accelerate future small-scale forward-genetic screening and identification of mutations. Therefore, the mangrove killifish could be used as a complementary system alongside existing models for future molecular genetic studies.

Transformed Canine and Murine Mesenchymal Stem Cells as a Model for Sarcoma with Complex Genomics

Simple Summary

Sarcomas are rare cancers of mesenchymal origin, the majority of which are characterized by many copy number alterations, amplifications, or deletions. Because of these complex genomics, it is notoriously difficult to identify driver events of malignant transformation. In this study, we show that murine and canine mesenchymal stem cells (MSCs) can be used to model spontaneous malignant transformation towards sarcomas with complex genomics. We show that these MSCs have an abnormal karyotype, many structural variants, and point mutations at whole genome sequencing analysis, and form sarcomas after injection into mice. Our cross-species analysis reveals that p53 loss is an early event in sarcomagenesis, and it was shown that MSCs with a knock-out in Trp53 transform earlier compared to wild-type MSCs. Our study points to the importance of p53 loss in the transformation process towards sarcomas with complex genomics.

Abstract

Sarcomas are rare mesenchymal tumors with a broad histological spectrum, but they can be divided into two groups based on molecular pathology: sarcomas with simple or complex genomics. Tumors with complex genomics can have aneuploidy and copy number gains and losses, which hampers the detection of early, initiating events in tumorigenesis. Often, no benign precursors are known, which is why good models are essential. The mesenchymal stem cell (MSC) is the presumed cell of origin of sarcoma. In this study, MSCs of murine and canine origin are used as a model to identify driver events for sarcomas with complex genomic alterations as they transform spontaneously after long-term culture. All transformed murine but not canine MSCs formed sarcomas after subcutaneous injection in mice. Using whole genome sequencing, spontaneously transformed murine and canine MSCs displayed a complex karyotype with aneuploidy, point mutations, structural variants, inter-chromosomal translocations, and copy number gains and losses. Cross-species analysis revealed that point mutations in Tp53/Trp53 are common in transformed murine and canine MSCs. Murine MSCs with a cre-recombinase induced deletion of exon 2–10 of Trp53 transformed earlier compared to wild-type murine MSCs, confirming the contribution of loss of p53 to spontaneous transformation. Our comparative approach using transformed murine and canine MSCs points to a crucial role for p53 loss in the formation of sarcomas with complex genomics.

A laboratory investigation into features of morphology and physiology for their potential to predict reproductive success in male frogs

Amphibian populations are declining globally, however, the contribution of reduced reproduction to declines is unknown. We investigated associations between morphological (weight/snout-vent length, nuptial pad colour/size, forelimb width/size) and physiological (nuptial pad/testis histomorphology, plasma hormones, gene expression) features with reproductive success in males as measured by amplexus success and fertility rate (% eggs fertilised) in laboratory maintained Silurana/Xenopus tropicalis. We explored the robustness of these features to predict amplexus success/fertility rate by investigating these associations within a sub-set of frogs exposed to anti-androgens (flutamide (50 μg/L)/linuron (9 or 45 μg/L)). In unexposed males, nuptial pad features (size/colour/number of hooks/androgen receptor mRNA) were positively associated with amplexus success, but not with fertility rate. In exposed males, many of the associations with amplexus success differed from untreated animals (they were either reversed or absent). In the exposed males forelimb width/nuptial pad morphology were also associated with fertility rate. However, a more darkly coloured nuptial pad was positively associated with amplexus success across all groups and was indicative of androgen status. Our findings demonstrate the central role for nuptial pad morphology in reproductive success in S. tropicalis, however, the lack of concordance between unexposed/exposed frogs complicates understanding of the utility of features of nuptial pad morphology as biomarkers in wild populations. In conclusion, our work has indicated that nuptial pad and forelimb morphology have potential for development as biomarkers of reproductive health in wild anurans, however, further research is needed to establish this.

ECOdrug: a database connecting drugs and conservation of their targets across species

Pharmaceuticals are designed to interact with specific molecular targets in humans and these targets generally have orthologs in other species. This provides opportunities for the drug discovery community to use alternative model species for drug development. It also means, however, there is potential for mode of action related effects in non-target wildlife species as many pharmaceuticals reach the environment through patient use and manufacturing wastes. Acquiring insight in drug target ortholog predictions across species and taxonomic groups has proven difficult because of the lack of an optimal strategy and because necessary information is spread across multiple and diverse sources and platforms. We introduce a new research platform tool, ECOdrug, that reliably connects drugs to their protein targets across divergent species. It harmonizes ortholog predictions from multiple sources via a simple user interface underpinning critical applications for a wide range of studies in pharmacology, ecotoxicology and comparative evolutionary biology. ECOdrug can be used to identify species with drug targets and identify drugs that interact with those targets. As such, it can be applied to support intelligent targeted drug safety testing by ensuring appropriate and relevant species are selected in ecological risk assessments. ECOdrug is freely accessible and available at: http://www.ecodrug.org.

Pharmacology beyond the patient - The environmental risks of human drugs

BACKGROUND

The presence of pharmaceuticals in the environment is a growing global concern and although environmental risk assessment is required for approval of new drugs in Europe and the USA, the adequacy of the current triggers and the effects-based assessments has been questioned.

OBJECTIVE

To provide a comprehensive analysis of all regulatory compliant aquatic ecotoxicity data and evaluate the current triggers and effects-based environmental assessments to facilitate the development of more efficient approaches for pharmaceuticals toxicity testing.

METHODS

Publicly-available regulatory compliant ecotoxicity data for drugs targeting human proteins was compiled together with pharmacological information including drug targets, Cmax and lipophilicity. Possible links between these factors and the ecotoxicity data for effects on, growth, mortality and/or reproduction, were evaluated. The environmental risks were then assessed based on a combined analysis of drug toxicity and predicted environmental concentrations based on European patient consumption data.

RESULTS

For most (88%) of the of 975 approved small molecule drugs targeting human proteins a complete set of regulatory compliant ecotoxicity data in the public domain was lacking, highlighting the need for both intelligent approaches to prioritize legacy human drugs for a tailored environmental risk assessment and a transparent database that captures environmental data. We show that presence/absence of drug-target orthologues are predictive of susceptible species for the more potent drugs. Drugs that target the endocrine system represent the highest potency and greatest risk. However, for most drugs (>80%) with a full set of ecotoxicity data, risk quotients assuming worst-case exposure assessments were below one in all European countries indicating low environmental risks for the endpoints assessed.

CONCLUSION

We believe that the presented analysis can guide improvements to current testing procedures, and provide valuable approaches for prioritising legacy drugs (i.e. those registered before 2006) for further ecotoxicity testing. For drugs where effects of possible concern (e.g. behaviour) are not captured in regulatory tests, additional mechanistic testing may be required to provide the highest confidence for avoiding environmental impacts.

Molecular Mechanisms of White Spot Syndrome Virus Infection and Perspectives on Treatments

Since its emergence in the 1990s, White Spot Disease (WSD) has had major economic and societal impact in the crustacean aquaculture sector. Over the years shrimp farming alone has experienced billion dollar losses through WSD. The disease is caused by the White Spot Syndrome Virus (WSSV), a large dsDNA virus and the only member of the Nimaviridae family. Susceptibility to WSSV in a wide range of crustacean hosts makes it a major risk factor in the translocation of live animals and in commodity products. Currently there are no effective treatments for this disease. Understanding the molecular basis of disease processes has contributed significantly to the treatment of many human and animal pathogens, and with a similar aim considerable efforts have been directed towards understanding host-pathogen molecular interactions for WSD. Work on the molecular mechanisms of pathogenesis in aquatic crustaceans has been restricted by a lack of sequenced and annotated genomes for host species. Nevertheless, some of the key host-pathogen interactions have been established: between viral envelope proteins and host cell receptors at initiation of infection, involvement of various immune system pathways in response to WSSV, and the roles of various host and virus miRNAs in mitigation or progression of disease. Despite these advances, many fundamental knowledge gaps remain; for example, the roles of the majority of WSSV proteins are still unknown. In this review we assess current knowledge of how WSSV infects and replicates in its host, and critique strategies for WSD treatment.

De novo assembly of the Carcinus maenas transcriptome and characterization of innate immune system pathways

Background

The European shore crab, Carcinus maenas, is used widely in biomonitoring, ecotoxicology and for studies into host-pathogen interactions. It is also an important invasive species in numerous global locations. However, the genomic resources for this organism are still sparse, limiting research progress in these fields. To address this resource shortfall we produced a C. maenas transcriptome, enabled by the progress in next-generation sequencing technologies, and applied this to assemble information on the innate immune system in this species.

Results

We isolated and pooled RNA for twelve different tissues and organs from C. maenas individuals and sequenced the RNA using next generation sequencing on an Illumina HiSeq 2500 platform. After de novo assembly a transcriptome was generated encompassing 212,427 transcripts (153,699 loci). The transcripts were filtered, annotated and characterised using a variety of tools (including BLAST, MEGAN and RSEM) and databases (including NCBI, Gene Ontology and KEGG). There were differential patterns of expression for between 1,223 and 2,741 transcripts across tissues and organs with over-represented Gene Ontology terms relating to their specific function. Based on sequence homology to immune system components in other organisms, we show both the presence of transcripts for a series of known pathogen recognition receptors and response proteins that form part of the innate immune system, and transcripts representing the RNAi, Toll-like receptor signalling, IMD and JAK/STAT pathways.

Conclusions

We have produced an assembled transcriptome for C. maenas that provides a significant molecular resource for wide ranging studies in this species. Analysis of the transcriptome has revealed the presence of a series of known targets and functional pathways that form part of their innate immune system and illustrate tissue specific differences in their expression patterns.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1667-1) contains supplementary material, which is available to authorized users.

The factor VIII inhibitor assays can be standardized: results of a workshop

BACKGROUND

The Bethesda and the Nijmegen assays are commonly used for the measurement of inhibitor levels in hemophilia A patients. Despite test innovations, the between-laboratory coefficient of variation (CVb) of factor VIII inhibitor test data in external quality surveys remains very high (40-60%) with a high degree of false-negative and false-positive results resulting in undesired effects on treatment.

OBJECTIVES

Organization of a workshop in order to address the causes of this phenomenon and to suggest ways to improve the assays.

METHODS

Fifteen laboratories showing a high CVb in regular surveys and using a variety of methods participated in the wet workshop, which included four different sessions where variables probably contributing to the high CVb (e.g. use of [non-]buffered plasma, FVIII-deficient plasma, sample dilution and APTT reagents) were investigated.

RESULTS

The CVb varied from 30% to 70% in the first session of the workshop when the participants used their own test settings and reagents. The use of buffered normal pooled plasma and FVIII-deficient plasma as a reference sample by all participants did not significantly alter the CVb (35-50%) but decreased the number of false positives. However, the use of buffered pooled plasma in combination with standardized sample dilution procedures by all participants showed a significant improvement (CVb, 10-20%).

CONCLUSIONS

These results may contribute to improvement of FVIII inhibitor testing. However, improved inter-laboratory comparison of factor VIII inhibitor assay results can only be reached when further local standardization is implemented.

Integrating Protein-Protein Interaction Networks with Gene- Gene Co-Expression Networks improves Gene Signatures for Classifying Breast Cancer Metastasis

Multiple studies have illustrated that gene expression profiling of primary breast cancers throughout the final stages of tumor development can provide valuable markers for risk prediction of metastasis and disease sub typing. However, the identification of a biologically interpretable and universally shared set of markers proved to be difficult. Here, we propose a method for de novo grouping of genes by dissecting the proteinprotein interaction network into disjoint sub networks using pair wise gene expression correlation measures. We show that the obtained sub networks are functionally coherent and are consistently identified when applied on a compendium composed of six different breast cancer studies. Application of the proposed method using different integration approaches underlines the robustness of the identified sub network related to cell cycle and identifies putative new sub network markers for metastasis related to cell-cell adhesion, the proteasome complex and JUN-FOS signalling. Although gene selection with the proposed method does not directly improve upon previously reported cross study classification performances, it shows great promises for applications in data integration and result interpretation.

The type of factor VIII deficient plasma used influences the performance of the Nijmegen modification of the Bethesda assay for factor VIII inhibitors

We have investigated the influence of the type of factor VIII deficient plasma used on the assay results of the Nijmegen modification of the Bethesda method for factor VIII inhibitors. Immuno depleted factor VIII deficient plasmas, lacking besides factor VIII also von Willebrand factor, gave decreased inhibitor titres compared to assay results with factor VIII deficient plasmas containing von Willebrand factor suggesting the need of the latter in the test system for the stability of factor VIII:C. Moreover the performance of the assay with immuno depleted plasma was contaminated in a certain type of this plasma by the presence of a factor VIII:C inhibitor. Chemically depleted factor VIII deficient plasma appeared to give falsely elevated titres when used in combination with other types of deficient plasmas as substrate plasma in the factor VIII:C assay due to the presence of activated factor Va in the preparation. Suggestions are described with respect to the observed limitations in order to obtain reliable results.

Hyperhomocysteinemia and other thrombotic risk factors in women with placental vasculopathy

OBJECTIVE

To investigate coagulation inhibitors and abnormalities of the homocysteine metabolism, which are related to an increased thrombotic risk, as risk factors for placental vasculopathy.

DESIGN

A case-control study comparing nonpregnant women with an obstetric history of placental vasculopathy (study group) with nonpregnant women (control group) matched for age and occupation.

SETTING

Obstetric outpatient clinic in the University Hospital Nijmegen.

SAMPLE

One hundred and one women in the study group and 92 women in a control group.

METHODS

Determinations in blood samples of homocysteine concentrations; the occurrence of 677 C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene; protein C activities; activated protein C resistance ratios; concentrations of free protein S antigen; antithrombin III activities; and the occurrence of factor V Leiden mutation.

RESULTS

Increased risk for placental vasculopathy was found in the study group with elevated homocysteine (odds ratio 2.28, 95% CI 1.18-4.39), MTHFR mutation (odds ratio 3.29, 95% CI 1.03-10.5), decreased activated protein C resistance ratio (odds ratio 2.46, 95% CI 1.06-5.72) and protein C (odds ratio 2.01, 95% CI 1.11-3.65). Any combination of two risk factors in the same individual resulted in a 3.40 (95% CI 1.80-6.42) higher relative risk for placental vasculopathy; combinations of three risk factors in a 6.83 (95% CI 1.52-30.7) higher risk.

CONCLUSIONS

The thrombotic risk factors decreased levels of activated protein C resistance ratios and protein C, elevated homocysteine and the MTHFR 677 C-->T mutation are likely risk factors for placental vasculopathy. Combinations of these risk factors in one individual resulted in synergistic increase of risk.

Meloxicam, 15 mg/day, spares platelet function in healthy volunteers

OBJECTIVE

To study the influence of meloxicam, a cyclooxygenase-2 (COX-2) preferential nonsteroidal anti-inflammatory drug, on serum thromboxane and platelet function in healthy volunteers with use of the maximum recommended daily dosage of 15 mg/day.

METHODS

This study used an open, randomized crossover design. Indomethacin (INN, indometacin) was given as a positive control for nonsteroidal anti-inflammatory drug-induced inhibition of platelet function. The following variables were recorded: thromboxane B2 serum concentrations by radioimmunoassay, platelet aggregation by whole blood aggregometry in response to collagen 1.1 microg/L and to arachidonic acid 0.35 mmol/L, and closure time with use of the PFA-100.

RESULTS

Serum thromboxane B2 at baseline was 535+/-233 nmol/L (mean +/- SD) and was reduced for 95% by indomethacin to 26+/-19 nmol/L (P < .001) and for 66% by meloxicam to 183+/-62 nmol/L (P < .001). Maximal platelet aggregation in response to collagen at baseline was 18.7+/-1.6 ohms (ohms). It was reduced by indomethacin to 7.3+/-4.5 ohms (P < .001), but not by meloxicam (19+/-2.5 ohms). Platelet aggregation in response to arachidonic acid at baseline was 12.2+/-2.0 ohms. It was reduced by indomethacin in all subjects to 0 ohms, but not by meloxicam (11+/-2.4 ohms). Closure time at baseline was 128+/-24 seconds and was prolonged by indomethacin to 286+/-38 seconds (P < .001). Meloxicam caused a minor prolongation of the closure time (141+/-32 seconds; P < .05).

CONCLUSION

Meloxicam, 15 mg/day caused a major reduction of maximum thromboxane production but no reduction in collagen- or arachidonic acid-induced platelet aggregation and only minor increase of the closure time.

Rapid D-dimer assays to exclude deep venous thrombosis and pulmonary embolism: current status and new developments

Studies measuring the fibrin degradation product D-Dimer (DD) using enzyme-linked immunosorbent assays (ELISA) in patients suspected of deep venous thrombosis (DVT) or pulmonary embolism (PE) suggest that it is possible to exclude DVT/PE when the DD level is below a certain cut-off value. However, ELISA methods are time-consuming, bare high costs, and are only available in experienced laboratories. For this reason several rapid and less costly DD assays have been recently developed. This article reviews the current literature about rapid latex and ELISA DD assays in the diagnostic approach of DVT and PE. Two new latex assays seem suitable in clinical practice. The most extensively studied assay is the so-called SimpliRed DD, an autologous red cell agglutination test that can be performed on fresh whole blood. For DVT a sensitivity (Sens) and a negative predictive value (NPV) of 89-100% and 95-100%, respectively, have been reported, for PE 94-100% and 98-100%, respectively. The second test, Tinaquant, is a quantitative latex assay. Sens and NPV for DVT of 99% and 93% have been reported in one study. Two rapid ELISA assays have been investigated. The most extensively studied is the VIDAS DD assay, a fully automated quantitative ELISA method. Sens and NPV of 94-100% and 92-100% for DVT and both 100% for PE have been reported. For the other rapid ELISA, Instant IA DD, Sens and NPV of 92-93% and 76-77% have been reported for DVT. The last one is a qualitative assay giving only positive or negative results. These results show that low concentrations of plasma DD measured by especially SimpliRed or VIDAS DD, might be used to reliably rule out DVT or PE in clinically suspected patients. Tinaquant seems promising and has to be evaluated further. As for standard ELISA, increased DD concentrations are of no use because of the low specificity of the assays. Future studies should assess the clinical usefulness of both assays in management trials under routine conditions, in the frame of clinical decision-making diagnostic processes to prove that withholding further noninvasive testing and/or anticoagulants in patients with a low or negative DD is safe. Strategies to identify patients with false-negative results should be developed.

A detailed comparison of the performance of the standard versus the Nijmegen modification of the Bethesda assay in detecting factor VIII:C inhibitors in the haemophilia A population of Canada. Association of Hemophilia Centre Directors of Canada. Factor VIII/IX Subcommittee of Scientific and Standardization Committee of International Society on Thrombosis and Haemostasis

The Bethesda assay is widely used to monitor the development and progress of Factor VIII:C inhibitors. Factor VIII stability in the substrate plasma (normal pool) is compromised by pH shift and reduction in protein concentration. Preliminary study, by Verbruggen and colleagues (8), suggested a reduction in spuriously positive assay results may result from buffering the normal pool plasma substrate with imidazole to pH 7.4 and substituting Factor VIII deficient plasma for imidazole buffer in the control incubation mix. These laboratory findings have now been confirmed by the performance of both the standard and the modified Bethesda assays in parallel on 877 patient samples screened during the Factor VIII:C Inhibitor Surveillance Program instituted following the conversion of all Canadian haemophilia A patients to recombinant Factor VIII. Although this study does not address the question of the clinical significance of spurious positive assays, these laboratory findings do support the conclusions of Verbruggen and the modified assay has recently been endorsed by the Factor VIII/IX Subcommittee of the SSC.

Homozygous cystathionine beta-synthase deficiency, combined with factor V Leiden or thermolabile methylenetetrahydrofolate reductase in the risk of venous thrombosis

Severe hyperhomocysteinemia in its most frequent form, is caused by a homozygous enzymatic deficiency of cystathionine beta-synthase (CBS). A major complication in CBS deficiency is deep venous thrombosis or pulmonary embolism. A recent report by Mandel et al (N Engl J Med 334:763, 1996) postulated factor V Leiden (FVL) to be an absolute prerequisite for the development of thromboembolism in patients with severe hyperhomocysteinemia. We studied 24 patients with homocystinuria caused by homozygous CBS deficiency from 18 unrelated kindreds for FVL and for the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene and investigated their possible interaction in the risk of venous thrombosis. Thrombotic complications were diagnosed in six patients, of whom only one was a carrier of FVL. On the contrary, thermolabile MTHFR caused by the 677C-->T mutation, was frequently observed among homocystinuria patients, especially among those with thromboembolic complications: three of six homocystinuria patients who had suffered from a thromboembolic event had thermolabile MTHFR. These data indicate that FVL is not an absolute prerequisite and probably not even a major determinant of venous thrombosis in homocystinuria, but, interestingly, thermolabile MTHFR may constitute a significant risk factor for thromboembolic complications in this inborn error of methionine metabolism.

The Nijmegen modification of the Bethesda assay for factor VIII:C inhibitors: improved specificity and reliability

Antibodies against factor VIII coagulant activity can appear in haemophiliacs who are treated with factor VIII preparations but also spontaneously in non-haemophiliacs. The Bethesda assay is the most commonly used method to detect these antibodies, but it lacks specificity especially in the lower range resulting in unreliable data. Two modifications are proposed and tested to resolve the imperfections: 1. Buffering the normal plasma used in the assay- and control mixture with 0.1 M imidazole to pH 7.4. 2. Replacing the imidazole buffer in the control mixture by immunodepleted factor VIII deficient plasma. These modifications allow better discrimination between positive and negative samples and improve reliability.

Effects of oral and intramuscular vitamin K prophylaxis on vitamin K1, PIVKA-II, and clotting factors in breast fed infants

A randomised clinical trial was conducted to establish the effects of oral and intramuscular administration of vitamin K at birth on plasma concentrations of vitamin K1, proteins induced by vitamin K absence (PIVKA-II), and clotting factors. Two groups of about 165 healthy breast fed infants who received at random 1 mg vitamin K1 orally or intramuscularly after birth were studied at 2 weeks and 1 and 3 months of age. Although vitamin K1 concentrations were statistically significantly higher in the intramuscular group, blood coagulability, activities of factors VII and X and PIVKA-II concentrations did not reveal any difference between the two groups. At 2 weeks of age vitamin K1 concentrations were raised compared with reported unsupplemented concentrations and no PIVKA-II was detectable. At 3 months vitamin K1 concentrations were back at unsupplemented values and PIVKA-II was detectable in 11.5% of infants. Therefore, a repeated oral prophylaxis will be necessary to completely prevent (biochemical) vitamin K deficiency beyond the age of 1 month.

Interference of coumarin therapy with the "Heptest" owing to declining prothrombin concentrations

The Heptest kit (Haemachem, Inc., St. Louis, MO) for quantifying heparin in plasma is based on heparin-mediated inhibition of factor Xa, resulting in prolongation of clotting time. In 19 of 55 plasma samples obtained from 32 patients concurrently receiving coumarin and heparin, Heptest results exceeded true heparin values by more than 0.2 int. unit/mL; four samples showed a deviation exceeding 0.4 int. unit/mL. We show here that these deviations are caused by coumarin-induced decreases of plasma prothrombin. This problem can be circumvented by adding purified prothrombin or normal plasma to the assay mixture.

Interference of coumarin therapy with the "Heptest" owing to declining prothrombin concentrations

The Heptest kit (Haemachem, Inc., St. Louis, MO) for quantifying heparin in plasma is based on heparin-mediated inhibition of factor Xa, resulting in prolongation of clotting time. In 19 of 55 plasma samples obtained from 32 patients concurrently receiving coumarin and heparin, Heptest results exceeded true heparin values by more than 0.2 int. unit/mL; four samples showed a deviation exceeding 0.4 int. unit/mL. We show here that these deviations are caused by coumarin-induced decreases of plasma prothrombin. This problem can be circumvented by adding purified prothrombin or normal plasma to the assay mixture.