Modelling the exposure to chemicals for risk assessment: a comprehensive library of multimedia and PBPK models for integration, prediction, uncertainty and sensitivity analysis - the MERLIN-Expo tool.

MERLIN-Expo is a library of models that was developed in the frame of the FP7 EU project 4FUN in order to provide an integrated assessment tool for state-of-the-art exposure assessment for environment, biota and humans, allowing the detection of scientific uncertainties at each step of the exposure process. This paper describes the main features of the MERLIN-Expo tool. The main challenges in exposure modelling that MERLIN-Expo has tackled are: (i) the integration of multimedia (MM) models simulating the fate of chemicals in environmental media, and of physiologically based pharmacokinetic (PBPK) models simulating the fate of chemicals in human body. MERLIN-Expo thus allows the determination of internal effective chemical concentrations; (ii) the incorporation of a set of functionalities for uncertainty/sensitivity analysis, from screening to variance-based approaches. The availability of such tools for uncertainty and sensitivity analysis aimed to facilitate the incorporation of such issues in future decision making; (iii) the integration of human and wildlife biota targets with common fate modelling in the environment. MERLIN-Expo is composed of a library of fate models dedicated to non biological receptor media (surface waters, soils, outdoor air), biological media of concern for humans (several cultivated crops, mammals, milk, fish), as well as wildlife biota (primary producers in rivers, invertebrates, fish) and humans. These models can be linked together to create flexible scenarios relevant for both human and wildlife biota exposure. Standardized documentation for each model and training material were prepared to support an accurate use of the tool by end-users. One of the objectives of the 4FUN project was also to increase the confidence in the applicability of the MERLIN-Expo tool through targeted realistic case studies. In particular, we aimed at demonstrating the feasibility of building complex realistic exposure scenarios and the accuracy of the modelling predictions through a comparison with actual measurements.

Development of a standard documentation protocol for communicating exposure models.

An important step in building a computational model is its documentation; a comprehensive and structured documentation can improve the model applicability and transparency in science/research and for regulatory purposes. This is particularly crucial and challenging for environmental and/or human exposure models that aim to establish quantitative relationships between personal exposure levels and their determinants. Exposure models simulate the transport and fate of a contaminant from the source to the receptor and may involve a large set of entities (e.g. all the media the contaminants may pass though). Such complex models are difficult to be described in a comprehensive, unambiguous and accessible way. Bad communication of assumptions, theory, structure and/or parameterization can lead to lack of confidence by the user and it may be source of errors. The goal of this paper is to propose a standard documentation protocol (SDP) for exposure models, i.e. a generic format and a standard structure by which all exposure models could be documented. For this purpose, a CEN (European Committee for Standardisation) workshop was set up with objective to agree on minimum requirements for the amount and type of information to be provided on exposure models documentation along with guidelines for the structure and presentation of the information. The resulting CEN workshop agreement (CWA) was expected to facilitate a more rigorous formulation of exposure models description and the understanding by users. This paper intends to describe the process followed for defining the SDP, the standardisation approach, as well as the main components of the SDP resulting from a wide consultation of interested stakeholders. The main outcome is a CEN CWA which establishes terms and definitions for exposure models and their elements, specifies minimum requirements for the amount and type of information to be documented, and proposes a structure for communicating the documentation to different users.

Feto-feto-fetal transfusion syndrome in monozygotic monochorionic triamniotic triplets: vascular evaluation by a cast model.

A unique cast model of the placenta in a rare case of feto-feto-fetal triplet transfusion syndrome (FFFTTS) allowed the demonstration of why the transfusion syndrome developed in one fetus and not in the other two in that single placenta. The vasculature anatomy of a monochorionic triamniotic triplet placenta with FFFTTS of three healthy infants (one donor, two recipients) born in the 35th week of gestation was cast by means of dental casting materials. After the cast hardened, the tissue was corroded, revealing the cast blood vessels. The diameters and lengths of the chorionic blood and intraplacental vessels of the cast placenta were measured with a digital caliper. The cast revealed two artery-artery (A-A) anastomoses on the chorionic plate between the two recipients and the donor. Seven artery-vein (A-V) deep anastomoses connected only the arteries of the donor and the veins of the two recipients. The blood vessel connections among the fetuses allowed the evaluation of a pathologic case with its own control in a single placenta. From the vascular appearance, we speculate that the A-A anastomoses between the two fetuses protected them from developing blood transfusions, but that the A-V anastomoses contributed to their development.

Prediction of fetal weight by ultrasound: the contribution of additional examiners.

OBJECTIVES: To assess the contribution of additional examiners to: the average discrepancy between estimated and actual fetal weights; the correlation between estimated and actual fetal weights; the reduction in major (> 10%) discrepancies between estimated and actual fetal weights. DESIGN: Three experienced sonographers independently measured fetal biparietal diameter, head circumference, abdominal circumference and femur length in 39 fetuses at term. The estimated fetal weights were calculated for each examiner. Fetal biometric measurements were analyzed to obtain the source of differences in estimations among the examiners. Discrepancy, correlation and number of major (> 10%) discrepancies between the estimated and actual fetal weights were calculated for each examiner, and the contribution of additional examiners was analyzed. RESULTS: The differences in measurements of the biparietal diameter and femur length were lower than those of the head and abdominal circumferences. For each of the three examiners, the average discrepancy between the estimated and actual fetal weights was 6.1%, 5.9% and 6.3%. When the estimation was based on two examiners, the discrepancy decreased to 4.8-5.6%. The contribution of a third examiner was nil. Major (> 10%) discrepancies between estimated fetal weight and actual birth weight were found in seven, eight and nine estimations of the examiners. Estimation by two examiners decreased the number of major discrepancies, and estimation by all three examiners further decreased by approximately 50% the number of major discrepancies between the estimated and actual fetal weights. CONCLUSION: Measurements by multiple examiners changes only slightly the average number of discrepancies between estimated and actual fetal weights. However, the reduction in major (> 10%) discrepancies is statistically and clinically significant.

Persistent right umbilical vein: incidence and significance.

OBJECTIVES: To conduct a prospective evaluation of the incidence and neonatal outcome of fetuses with persistent right umbilical vein. This condition had traditionally been considered to be extremely rare and to be associated with a very poor neonatal prognosis, but later evidence has raised some doubts about the veracity of these contentions. METHODS: Between August 1995 and November 1998, 8950 low-risk patients were prospectively evaluated at two medical centers. The sonographic diagnosis of a persistent right umbilical vein was made in a transverse section of the fetal abdomen when the portal vein was curved toward the stomach, and the fetal gall bladder was located medially to the umbilical vein. RESULTS: Persistent right umbilical vein was detected in 17 fetuses during the study. Four of them had additional malformations, of which three had been detected antenatally. CONCLUSIONS: We established that the incidence of persistent right umbilical vein in a low-risk population is 1 : 526. We believe that the sonographic finding of this anomaly is an indication for conducting targeted fetal sonography and echocardiography. When the persistent right umbilical vein is connected to the portal system and other anomalies are ruled out, the prognosis can generally be expected to be favorable.

High levels of catecholamines in human semen: a preliminary study.

The objective of this study was to determine the seminal concentrations of four different catecholamines and their association with semen quality. Seminal concentrations of adrenaline, noradrenaline, 3,4-dihydroxy-phenylalanine (DOPA), and 3,4-dihydroxy-phenyl acetic acid (DOPAC) were determined in 13 healthy volunteers, using high-performance liquid chromatography with an electrochemical detector. In addition, semen analysis was performed. Noradrenaline and DOPA were present in all specimens with a concentration of 15 181+/- 2951 pg ml(-1) and 4023 +/- 429 pg ml(-1) (mean +/- SE), respectively. These concentrations are respectively 19 times (range: 3-44) and twice (range: 1-3) as high as the maximal normal concentration in plasma. Adrenaline was present in 10 and DOPAC in seven of 13 specimens. No correlation was found between the concentration of any of the catecholamines evaluated and semen characteristics. In conclusion, noradrenaline and DOPA are present in human semen at concentrations that are much higher than maximal normal values in plasma. Adrenaline and DOPAC were also found in some of the samples. The concentrations of catecholamines in semen are not associated with semen quality.

Vascularity index distribution within the testis: a technique for guiding testicular sperm extraction.

Azoospermia is defined as the absence of spermatozoa in the ejaculate, although some foci of spermatogenesis may exist in the testes of these men. Currently, there are no clinical, seminal or hormonal parameters for identifying spermatogenesis within the testis sufficient for achieving genetic offspring. As a result, multiple biopsies are performed at several arbitrary sites of both testes in search of spermatozoa. We developed a power Doppler (PD) ultrasound (US) image-based technique that predicts sites with the greatest potential for spermatogenesis. PDUS images of the testes of azoospermic men were acquired at seven cross-sections to reconstruct a 3-D matrix for constructing a spatial map of preferential regions where spermatozoa are most likely to exist. This technique may obviate the need for arbitrary multiple biopsies that inflict some degree of damage upon testicular tissue, and may increase the success rate of identifying viable spermatozoa in testicular biopsies.

Low-molecular-weight heparin for the prevention of obstetric complications in women with thrombophilias.

OBJECTIVE: To evaluate the benefit of combined low-molecular-weight (LMW) heparin and aspirin for prophylaxis in women carriers of thrombophilia who had previously suffered from severe obstetric complications. METHODS: The 33 studied women had an earlier pregnancy complicated by severe preeclampsia, abruptio placentae, intrauterine growth retardation, or intrauterine fetal death. All were subsequently diagnosed as carrying inherited thrombophilias. In their subsequent pregnancy, prophylactic therapy consisting of LMW heparin 40 mg/day (Enoxaparin, Rhone-Poulenc-Rorer, France) and aspirin was administered. Patients who were found to be homozygotes for the methylenetetrahydrofolate reductase mutation also received folic acid supplementation throughout their pregnancy. RESULTS: Low-molecular-weight heparin was well tolerated and none of the women or the newborns developed any hemorrhagic complications. Only three (9.1%) of the women developed pregnancy complications. The mean gestational age and the mean birth weight at delivery in the previously complicated pregnancies were 32.1 +/- 5.0 weeks and 1175 +/- 590 g, respectively, compared to 37.6 +/- 2.3 weeks and 2719 +/- 526 g, respectively, in the treated pregnancies (p < 0.001). CONCLUSIONS: This uncontrolled trial suggests that patients with obstetric complications and an inherited thrombophilia may benefit from treatment with combined LMW heparin and aspirin in subsequent pregnancies. However, this needs to be verified by controlled trials before considering clinical application.

Contribution of human papillomavirus testing by hybrid capture in the triage of women with repeated abnormal pap smears before colposcopy referral.

OBJECTIVE: The purpose of this work was to evaluate the ability of testing for high-risk human papillomavirus (HPV) types using the hybrid capture technique to predict the presence of cervical intraepithelial neoplasia (CIN) II,III in patients with repeated atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesion (LGSIL) on Pap smears. METHODS: Hybrid capture testing and tissue biopsy were performed on 503 consecutive women with ASCUS or LGSIL on repeated Pap smears who were referred for colposcopy. RESULTS: A highly significant association (P < 0.0001) was found between a positive test for high-risk HPV types and CIN II,III, with an 87.0% positive predictive value and a 95.7% negative predictive value. In 226 women with ASCUS on repeated Pap smears, a positive test for high-risk HPV types had a 85.7% sensitivity and a 97% specificity for CIN II,III. In 277 patients with LGSIL on repeated Pap smears, a positive test for high-risk HPV types had an 88.2% sensitivity and a 94.7% specificity for CIN I,II. Reserving colposcopy examination for women who were positive for high-risk HPV types would have reduced the number of referrals for colposcopy to 24.6% and maintained a sensitivity of 87.0% for CIN II,III. CONCLUSIONS: A positive hybrid capture test for high-risk HPV types was highly sensitive and specific for the presence of CIN II,III in patients with ASCUS and LGSIL on repeated Pap smears. We believe that improved methodology will eventually enable more selective colposcopy referrals without affecting patient safety among these women.

Analysis of 104 twin pregnancies conceived with assisted reproductive technologies and 193 spontaneously conceived twin pregnancies.

OBJECTIVE: To evaluate pregnancy outcome of assisted reproductive technology (ART)-conceived twin pregnancies. DESIGN: Retrospective study. SETTING: A tertiary obstetric care center. PATIENT(S): All twin pregnancies delivered > or = 24 weeks of gestation from January 1, 1996, to December 31, 1997. INTERVENTION(S): Maternal and neonatal record review. MAIN OUTCOME MEASURE(S): Pregnancy and perinatal outcome. RESULT(S): The study group comprised 104 ART-conceived twin pregnancies, and 193 non-ART-conceived pregnancies served as controls. Mean maternal age, the proportion of nulliparae, and the percentage of women who delivered before 34 weeks' gestation was higher among the study women, whereas mean gestational age was younger. The incidences of pregnancy-induced hypertension, uterine bleeding, premature contractions, intrauterine growth retardation, fetal death, discordance, and cesarean section were significantly higher in the study group. Correspondingly, in the study group, the mean birth weight of both twins was lower; more neonates weighed < 1, 500 g, more had Apgar scores of < 7 at 5 minutes, more were admitted to the intensive care unit, and more second twin neonates died. The outcome of twin pregnancies conceived spontaneously was comparable with those conceived by ovulation induction. CONCLUSION(S): Assisted reproductive technology-conceived twin pregnancies are at greater risk than non-ART-conceived ones for pregnancy complications and adverse perinatal outcome.

Severe preeclampsia and high frequency of genetic thrombophilic mutations.

OBJECTIVE: To determine whether severe preeclampsia is associated with genetic thrombophilic mutations or other types of thrombophilia. METHODS: A case-control study compared 63 consecutive women with severe preeclampsia evaluated at our institution between November 1997 and April 1999 with 126 control women matched for age and ethnicity. All of these women were tested several months after delivery for mutations of factor V Leiden, methylenetetrahydrofolate reductase, and prothrombin gene; for deficiencies of protein C, protein S, and antithrombin-III; and for the presence of anticardiolipin antibodies. RESULTS: Thirty-five study women (56%) had a thrombophilic mutation compared with 24 control women (19%), P <.001. Seven other study women (11%) had other thrombophilias, compared with one control woman (0.8%), P <.01. Within the study group, women with thrombophilia delivered at an earlier gestational age, and their neonates' birth weights were lower compared with those of women without thrombophilia. CONCLUSION: Because thrombophilia was found in 67% of women with severe preeclampsia, we suggest that women who have severe preeclampsia should be tested for thrombophilia.

Do soluble cell adhesion molecules play a role in endometriosis?

PROBLEM: Endometriosis is a chronic inflammatory disease associated with diverse immunologic disturbances. Cell adhesion molecules are essential for the development of immune and inflammatory reactions. This study was conducted to investigate whether or not serum and peritoneal levels of soluble cell adhesion molecules are altered in women with endometriosis. METHOD OF STUDY: The study group comprised five women with moderate-to-severe endometriosis. Eight healthy women with a normal diagnostic laparoscopy served as controls. Serum and peritoneal fluid samples from both groups were analyzed for the soluble isoform of intercellular cell adhesion molecule-1 (sICAM-1). vascular cell adhesion molecule-1 (sVCAM-1), endothelial selectin (sES), and platelet selectin (sPS). RESULTS: Serum levels of sICAM-1 were significantly increased in women with endometriosis (median levels: 410.4 ng/mL; range: 233.9 ng/mL 598.4 ng/mL vs. 235.7 ng/mL; range: 187.4 ng/mL -323.7 ng/mL; P = 0.02). Although the levels of sVCAM-1, sES, and sPS in both samples were higher in the study group, the differences did not reach significance. CONCLUSIONS: Our results suggest a role of ICAM-1 in the pathophysiology of endometriosis. However. the role of other investigated cell adhesion molecules should be confirmed by further studies.

Second-trimester multifetal pregnancy reduction facilitates prenatal diagnosis before the procedure.

OBJECTIVE: To evaluate the pregnancy outcome of selective second-trimester multifetal pregnancy reduction (MFPR) compared to first-trimester MFPR. DESIGN: Cohort analysis. SETTING: In Vitro Fertilization Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. PATIENT(S): The study groups comprised 38 and 70 patients who underwent selective second-trimester MFPR (group 1) and first-trimester MFPR (group 2) at mean gestational ages of 19.7 +/- 3.3 weeks and 11.7 +/- 0.7 weeks, respectively. INTERVENTION(S): Ultrasonographically guided intracardiac injection of potassium chloride (KCl) solution. MAIN OUTCOME MEASURE(S): Pregnancy outcome and obstetric complications. RESULT(S): No statistically significant difference was found between group 1 and group 2 regarding mean gestational age at delivery (35.4 +/- 3.4 weeks and 35.9 +/- 3.1 weeks, respectively); mean birth weight (2,318.9 +/- 565.7 g and 2, 138.1 +/- 529.4 g); and the incidence of obstetric complications. These complications included pregnancy loss (5.2% and 15.7%), pregnancy-induced hypertension (0 and 10%), discordancy (12% and 18. 4%), intrauterine growth restriction (0 and 40%), and gestational diabetes (0% and 6%). However, the rate of all pregnancy complications was lower among second-trimester MFPR patients. CONCLUSION(S): Selective second-trimester MFPR is associated with favorable perinatal outcome and may facilitate detection of structural and chromosomal anomalies before the procedure and selective reduction of the affected fetus.

The significance of the American Urological Association symptom index score in the evaluation of women with bladder outlet obstruction.

PURPOSE: The American Urological Association (AUA) symptom index was originally designed to assess the severity of lower urinary tract symptoms in men with benign prostatic hyperplasia. Data concerning the clinical application of the AUA symptom index to women are sparse. We evaluated the significance of the AUA symptom index in women with urodynamically defined bladder outlet obstruction. MATERIALS AND METHODS: From a urodynamic database of 587 consecutive women 38 (6.5%) were identified with bladder outlet obstruction, defined as a maximum flow rate of less than 12 ml. per second on repeat noninvasive uroflowmetry studies with a detrusor pressure at a maximum flow of greater than 20 cm. water on pressure flow study. All patients underwent a complete clinical and urodynamic evaluation, and completed the AUA symptom index questionnaire. Results in women with urodynamic obstruction were compared with those in 2 control groups, including women without obstruction but with sphincteric incontinence and asymptomatic healthy women. RESULTS: Mean symptom score was significantly higher in women with obstruction than in those with sphincteric incontinence or no symptoms (15.8+/-8.4 versus 10.3+/-6.4 and 2.1+/-2.7, respectively). Likewise, scores were classified as severe in 34% of women with obstruction compared with only 7% of those with sphincteric incontinence. However, no correlation was noted between symptom index scores and objective urodynamic parameters, which is similar to data already reported in male populations. CONCLUSIONS: The AUA symptom index score may be useful as a bothersomeness index in women with bladder outlet obstruction. However, subjective symptoms associated with bladder outlet obstruction are nonspecific and a complete urodynamic evaluation is essential for making the diagnosis.

The possible role of antiovary antibodies in repeated in vitro fertilization failures.

PROBLEM: The study was conducted to investigate the possible role of circulating ovarian autoantibodies (ov-ab) in patients with repeated in vitro fertilization embryo transfer (IVF-ET) failure and to evaluate the effectiveness of immunosuppression treatment in these patients. METHOD OF STUDY: The study group comprised 80 IVF patients who had five or more failed treatment cycles (mean 10.2; range 7-22). The presence of ov-ab was compared between these women and 1) 50 IVF patients who conceived during the first three treatment cycles; 2) 50 healthy nulligravidae. All participants were seronegative to nonorgan-specific and antithyroid autoantibodies. Patients in the study group who were positive for ov-ab were treated with 10 mg/day prednisone starting 1 month before ovulation induction. Embryo grading was compared in the IVF cycles before and after treatment. RESULTS: Ov-ab were found in ten patients (12.5%) in the study group, compared to none in the control groups (P = 0.01). Nine of the patients positive for ov-ab were treated with prednisone for their following cycle. A statistically significant improvement in embryo grading was noted. Three patients conceived after treatment (33%), with a take-home baby rate of 22%, compared to only six patients (8.6%) who conceived among the rest of the seronegative study group, with a take-home baby rate of 7.1% (P = 0.05). CONCLUSIONS: Ov-ab are a possible marker of an autoimmune disorder that may be one of the causes of repeated IVF failures. Immunosuppression treatment may prove efficient in ov-ab seropositive patients with repeated IVF failures by improving embryo grading and pregnancy rate.

A selective increase in plasma soluble vascular cell adhesion molecule-1 levels in preeclampsia.

PROBLEM: The study was conducted to determine whether altered plasma levels of soluble intercellular adhesion molecule (ICAM)-1 and soluble vascular cell adhesion molecule (VCAM)-1 are involved in the pathogenesis of preeclampsia. METHOD OF STUDY: Maternal plasma samples were collected from 20 patients with preeclampsia, 20 matched normotensive patients with uncomplicated pregnancies. and ten healthy nonpregnant women. Samples were assayed for soluble VCAM-1 and soluble ICAM-1 by specific enzyme-linked immunosorbent assay. RESULTS: Both soluble VCAM-1 and soluble ICAM-1 were detectable in the plasma of all preeclamptic, normotensive pregnant, and nonpregnant women. The mean plasma level of soluble VCAM-1 was significantly higher in preeclamptic women compared to normotensive pregnant women (1831 ng/mL +/- 534 ng/mL vs. 1254 ng/mL +/- 386 ng/mL, respectively; P < 0.05). However, the plasma level of soluble VCAM-1 was unchanged during the third-trimester of normal pregnancy compared to nonpregnant women. The mean plasma level of soluble ICAM-1 in preeclamptic and normotensive pregnant women were increased when compared to nonpregnant women. However, the mean plasma level of soluble ICAM-1 was comparable in women with preeclampsia and normotensive pregnancy. CONCLUSIONS: The selective increased plasma levels of soluble VCAM-1 in patients with preeclampsia provide evidence for endothelial activation and suggest distinct pathways for neutrophil and endothelial activation in preeclampsia.

Levels of soluble vascular cell adhesion molecule-1 and soluble intercellular adhesion molecule-1 are increased in women with ovarian hyperstimulation syndrome.

OBJECTIVE: To determine whether plasma and peritoneal fluid levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecule-1 (sICAM-1) are altered in women with ovarian hyperstimulation syndrome (OHSS). DESIGN: Prospective, case-control study. SETTING: Lis Maternity Hospital and the Sara Racine IVF Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. PATIENT(S): The study group comprised 16 women with severe OHSS. The control groups comprised 10 women treated with controlled ovarian hyperstimulation and 8 women with normal findings at diagnostic laparoscopy. INTERVENTION(S): Plasma samples were obtained from the study group and the first control group. Peritoneal fluid samples were obtained during paracentesis from the study group and during diagnostic laparoscopy from the second control group. MAIN OUTCOME MEASURE(S): Samples were assayed by specific ELISA for sVCAM-1 and sICAM-1. RESULT(S): The mean peritoneal fluid levels of sVCAM-1 and sICAM-1 and the mean plasma levels of sVCAM-1 were significantly higher in the women with OHSS than in the control groups. However, the mean plasma levels of sICAM-1 were comparable. A positive correlation was demonstrated between the levels of sVCAM-1 and plasma E2 at the time of hCG administration and between the levels of sICAM-1 and number of ova retrieved. CONCLUSION(S): Our findings suggest that soluble cell adhesion molecules may have a role in the pathogenesis and progression of OHSS.