Exposure to an anti-androgenic herbicide negatively impacts reproductive physiology and fertility in Xenopus tropicalis.

Amphibians are threatened on a global scale and pollutants may be contributing to population declines, but how chemicals impact on their reproduction is poorly understood. We conducted a life cycle analysis to investigate the impacts of early life exposure to two anti-androgens (exposure until completion of metamorphosis;stage 66): flutamide, (50 µg/L)/linuron (9 and 45 µg/L)) on sexual development and breeding competence in Xenopus tropicalis. Our analyses included: mRNA levels of dmrt1, cyp17, amh, cyp19, foxl2 and ar (tadpoles/metamorphs), gonadal histomorphology (metamorphs/adults), mRNA levels of ar/gr (adult male brain/gonad/forelimb), testosterone/corticosterone levels (adult males), secondary sexual characteristics (forelimb width/nuptial pad: adult males) and breeding competence (amplexus/fertility: adult males). Compared to controls, feminised sex ratios and increased number of spermatogonia (adults) were observed after exposure to flutamide and the lower linuron concentration. Exposure to the lower linuron concentration also resulted in demasculinisation of secondary sexual characteristics and reduced male fertility. Flutamide exposure resulted in masculinisation of the nuptial pad and elevated mRNA levels of dmrt1, cyp17, amh and foxl2 in brains (metamorphs). Testosterone levels were higher in all treatment groups, however, overall few effects were observed in response to the higher linuron concentration. Our findings advance understanding of reproductive biology of X. tropicalis and illustrate negative effects of linuron on reproductive processes at a concentration measured in freshwater environments.

Laboratory testing for factor inhibitors.

Inhibitor assays are performed when patients present with unexplained prolonged routine coagulation test times and unexpected and/or unusual bleeding (potential for acquired haemophilia) as well as being a part of normal congenital haemophilia management and monitoring, particularly when bleeding occurs on therapy, or when increments in factor levels post-factor replacement remain lower than expected. In this article, we will describe the assays used, as well as their development, pitfalls in testing such as inter-laboratory variability and false negative/positive results, as well as some strategies for overcoming these pitfalls and potential alternative test approaches. The inter-laboratory coefficient of variation often approaches (and sometimes exceeds) 50%, as evidenced by various external quality assessment groups, and this variability has not improved over recent years. Additional important considerations include appropriate interpretation of test results, repeat testing for confirmation, and assessment of recovery as part of the diagnostic process.

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.

Haemophilia A and von Willebrand's disease.

SUMMARY: Deficient or defective coagulation factor VIII (FVIII) and von Willebrand factor (VWF) can cause bleeding through congenital deficiency or acquired inhibitory antibodies. Recent studies on type 1 von Willebrand's disease (VWD), the most common form of the disease, have begun to explain its pathogenesis. Missense mutations of varying penetrance throughout VWF are the predominant mutation type. Other mutation types also contribute while about one-third of patients have no mutation identified. Enhanced clearance and intracellular retention contribute to pathogenic mechanisms. Chromogenic substrate (CS) methods to determine FVIII coagulant activity have several advantages over one-stage methods, which include minimal influence by variable levels of plasma components, notably lupus anticoagulant. Direct proportionality between FVIII activity and FXa generation results in high resolution at all FVIII levels, rendering the CS method suitable for measuring both high and low levels of FVIII activity. FVIII inhibitors in patients with inherited or acquired haemophilia A present several challenges in their detection and accurate quantification. The Nijmegen method, a modification of the Bethesda assay is recommended for inhibitor analysis by the International Society on Thrombosis and Haemostasis. Understanding potential confounding factors including heparin and residual FVIII in test plasma, plus optimal standardization can reduce assay coefficient of variation to 10-20%.These areas are all explored within this article.

Diagnosis and quantification of factor VIII inhibitors.

The laboratory detection of factor VIII inhibitors is invariably performed by methods that measure the inactivation of factor VIII in mixtures of test plasma and exogenous factor VIII, e.g. normal pooled plasma. Unfortunately the intra- and inter-laboratory variation of the inhibitor assays is rather high often resulting in unreliable results. The pH of the mixtures of test plasma and pooled plasma, incubation time and temperature, type of control sample, von Willebrand content of factor VIII deficient plasma that is used in the assay and the presence of lupus anticoagulant all influence and/or interfere with the results of inhibitor testing. In this review these assay characteristics, pitfalls and limitations of the assays are discussed.

Diagnosis of factor VIII deficiency.

The correct diagnosis of factor VIII deficiency and the assessment of severity of the disease are essential for a patient-tailored treatment strategy. An optimal diagnostic procedure comprises sensitive and specific screening methods and factor VIII activity assays. Different screening reagents show variable characteristics and receiver operator characteristic curves are presented showing the relation between sensitivity and specificity of eleven activated partial thromboplastin time reagents. The details of the three methods for factor VIII activity assay, one-stage and two-stage assay and chromogenic assays, are discussed. The chromogenic assay seems to be more sensitive than the one-stage assay with regard to the detection of severe haemophilia. Discrepant results obtained with one-stage and two-stage assays are reviewed and discussed.

Candida and squamous (pre)neoplasia of immigrants and Dutch women as established in population-based cervical screening.

The objective of this study was to establish the relationship between Candida vaginalis and (pre)neoplasia and the prevalence of Candida and (pre)neoplasia related to age and ethnicity. Data were collected from 445,671 asymptomatic women invited for mass screening between 1995 and 2002 and coded according to the Dutch cervical smear coding system (KOPAC) with six grades for (pre)neoplastic changes. Prevalence and relative risks (RRs) were established for Candida and squamous abnormalities in Dutch women and four groups of immigrants. The prevalence of Candida is significantly higher in the cohort of 30-year-old women and lower in the cohorts of 45-, 50-, 55-, and 60-year-old women. The RR of having Candida was higher for Surinamese women (1.24; CI 1.08-1.42). Furthermore, the RR of having mild dysplasia was higher for Surinamese women (1.47; CI 1.14-1.89) and for women born in other countries than in The Netherlands, Turkey, and Morocco (1.36; CI 1.13-1.62). No statistically significant relationship between (pre)neoplasia and Candida was observed. C. vaginalis is more frequent among Surinamese women. Presence of Candida is not associated with an increased risk for squamous abnormalities; therefore, women carrying Candida are not at an increased risk of developing cervical cancer.

Koilocytosis and squamous (pre)neoplasia as detected in population-based cervical screening: practice and theory.

INTRODUCTION: Koilocytosis (cavitation of the cytoplasm due to active HPV infection) can be detected in the screening process for cervical carcinoma. OBJECTIVE: To report the practice of detection of koilocytosis and (pre)neoplasia in population screening and to exploit the collected data to propose an explanation for the relationship between HPV infection and nuclear precancerous changes. STUDY DESIGN: Centrally collected and stored (SBBW, Leiden, the Netherlands) data from all smears of six regional pathology laboratories (1995-2002), coded according to KOPAC (the national cervical smear coding system; S1: normal thru S9: invasive carcinoma) were accessed. Prevalences per 100,000 smears were calculated for koilocytosis and for squamous abnormalities after stratification for country of origin of screenees. The relative risk (RR) for the ethnic (age) groups was computed by dividing the prevalence of the relevant ethnic (age) group by the prevalence of all women. RESULTS: Surinamese women featured the highest prevalence of koilocytosis and of all squamous abnormalities. Moroccan women the lowest. The RR for koilocytosis was highest at 30 years (1.84) and lowest at 60 (0.26). RR dependence on age of S5-S9 lesions was similar. Compared to nonkoilocytotic smears, koilocytosis was 104 times more frequent in the 1,500 S4 smears, 36x more frequent in the 6,700 S2-S3 smears, and 24x more frequent in the 1,740 S5-S9 smears. In all three categories this difference is statistically significant. CONCLUSION: High prevalences for both koilocytosis and for preneoplasia were detected in Surinamese immigrants, however, it still does not exclude HPV infection as a confounder linked to sexual lifestyle. The presence of koilocytosis in cervical smears may serve to identify patients with an increased risk for cervical cancer and perhaps warrant more intensive surveillance than what is provided through five-yearly screening.

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.