HIGHLY LOCALIZED AZIMUTHAL MEASUREMENTS IN THE CROCUS REACTOR TOWARDS THE VALIDATION OF HIGH-FIDELITY NEUTRONICS CODES

Highly localized in-core measurements are necessary for the validation of neutron transport calculations with high spatial resolution. In the present work, a miniature neutron detector developed at EPFL in collaboration with PSI was used to carry out a set of thermal neutrons counting measurements in the zero-power CROCUS reactor core within a spatial range in order of mm. The miniature detector, positioned close to the core reflector, shows a gradient of +(4.29 ± 0.10)% in the count rate profile in the radial direction within 1.3 cm, with higher values pointing towards the core reflector because of the higher share of neutrons in the thermal range. On the contrary, in a control rod guide tube the count rate gradient is -(4.37 ± 0.10)% and it is directed towards the core center. The measured values are compared with the azimuthal trend of the normalized 6Li reaction rate calculated with an iterative three-steps method performed with the Monte Carlo code Serpent 2. These measurements proved the feasibility of resolving spatial effects in the mm-range and they represent a basis for further investigating highly spatially-resolved phenomena in the CROCUS core.

VALIDATION OF AXIAL VOID PROFILE MEASURED BY NEUTRON NOISE TECHNIQUES IN CROCUS

Recently a joint project has been carried out between the Paul Scherrer Institut, the Ecole Polytechnique Federale de Lausanne and swissnuclear, an industrial partner, in order to determine the axial void distribution in a channel installed in the reflector of the zero power research reactor CROCUS, using neutron noise techniques. The main objective of the present paper is to report on the validation of the results against an alternative measurement technique using gamma-ray attenuation and simulations with the TRACE code. For the gamma-ray attenuation experiments, the channel used in CROCUS is installed out of the core in a Plexiglass water tank. The source and detector are fixed and the channel is moved axially to keep the geometry of the source/detector arrangement untouched. This is key to measure the void effect by gamma attenuation due to the low contrast of this technique. The paper compares the experimental results obtained with both techniques, with the outcomes of simulations carried out with the TRACE code. Even though the quantitative void fraction estimations are not consistent, the trends obtained with the simulation and experimental techniques are the same. The discrepancies between the various experimental techniques and the simulation outcomes are related to the heterogeneous distribution of the water-air mixture in the radial sections of the channel.

CORE SIM+ SIMULATIONS OF COLIBRI FUEL RODS OSCILLATION EXPERIMENTS AND COMPARISON WITH MEASUREMENTS

At EPFL, the CROCUS reactor has been used to carry out experiments with vibrating fuel rods. The paper presents a first attempt to employ the measured data to validate CORE SIM+, a neutron noise solver developed at Chalmers University of Technology. For this purpose, the original experimental data are processed in order to extract the necessary information. In particular, detector recordings are scrutinized and detrended, and used to estimate CPSDs of detector pairs. These values are then compared with the ones derived from the CORE SIM+ simulations of the experiments. The main trend of the experimental data along with the values for some detectors are successfully reproduced by CORE SIM+. Further work is necessary on both the experimental and computational sides in order to improve the validation process.

NEUTRON EMISSION MEASUREMENTS OF PWR SPENT FUEL SEGMENTS AND PRELIMINARY VALIDATION OF DEPLETION CALCULATIONS

Assessing neutron emission of LWR spent fuel is necessary for the back-end of the fuel cycle, such as the dimensioning of transport and storage casks of spent fuel. Although core and depletion codes can calculate the isotopic composition of the discharged fuel and therefore infer its neutron source, accurate measured neutron emission values remain rare mainly because of the difficulty to prepare, handle and characterize spent fuel. Measured neutron emission values are, however, extremely relevant to code validation, as neutrons emitted by LWR spent fuel mainly originates from spontaneous fissions of minor actinides (e.g., 242Cm, 244Cm and 252Cf) that are produced only after a large number of neutron captures in the reactor core. This paper reports on neutron emission measurements of selected LWR-PROTEUS spent fuel samples and their comparisons with a core and depletion calculation chains based on CASMO-5, SIMULATE-3 and the SNF codes. The measured LWR-PROTEUS samples are comprised of 11 samples irradiated in a Swiss PWR. The samples are UO2 or MOX and have discharge burn-ups ranging from 20 to 120 GWd/t. We measured the 40-cm long samples in a hot-cell of the Paul Scherrer Institut using a measurement station made of polyethylene and a BF3 detector. We repeated the measurements several times and in different conditions to ensure the accuracy and reproducibility of the results. We derived ratios of neutron rates emitted by the different samples and absolute neutron emission rates by comparison with a reference 252Cf source, which we re-calibrated for this exercise. The experimental uncertainty (1σ) on the absolute neutron emission varies from 3% to 4%. We compared a subset of the measured values to the calculation predictions and showed an agreement within less than 7% for all but one sample.

ANALYSIS OF THE FIRST COLIBRI FUEL RODS OSCILLATION CAMPAIGN IN THE CROCUS REACTOR FOR THE EUROPEAN PROJECT CORTEX

The Horizon2020 European project CORTEX aims at developing an innovative core monitoring technique that allows detecting anomalies in nuclear reactors, such as excessive vibrations of core internals, flow blockage, or coolant inlet perturbations. The technique will be mainly based on using the fluctuations in neutron flux recorded by in-core and ex-core instrumentation, from which the anomalies will be differentiated depending on their type, location and characteristics. The project will result in a deepened understanding of the physical processes involved, allowing utilities to detect operational problems at a very early stage. In this framework, neutron noise computational methods and models are developed. In parallel, mechanical noise experimental campaigns are carried out in two zero-power reactors: AKR-2 and CROCUS. The aim is to produce high quality neutron noise-specific experimental data for the validation of the models. In CROCUS, the COLIBRI experimental program was developed to investigate experimentally the radiation noise induced by fuel rods vibrations. In this way, the 2018 first CORTEX campaign in CROCUS consisted in experiments with a perturbation induced by a fuel rods oscillator. Eighteen fuel rods located at the periphery of the core fuel lattice were oscillated between ±0.5 mm and ±2.0 mm around their central position at a frequency ranging from 0.1 Hz to 2 Hz. Signals from 11 neutron detectors which were set at positions in-core and ex-core in the water reflector, were recorded. The present article documents the results in noise level of the experimental campaign. Neutron noise levels are compared for several oscillation frequencies and amplitudes, and at the various detector locations concluding to the observation of a spatial dependency of the noise in amplitude.

Aptamer-Based Affinity Chromatography for Protein Extraction and Purification

Aptamers are oligonucleotide molecules able to recognize very specifically proteins. Among the possible applications, aptamers have been used for affinity chromatography with effective results and advantages over most advanced protein separation technologies. This chapter first discusses the context of the affinity chromatography with aptamer ligands. With the adaptation of SELEX, the chemical modifications of aptamers to comply with the covalent coupling and the separation process are then extensively presented. A focus is then made about the most important applications for protein separation with real-life examples and the comparison with immunoaffinity chromatography. In spite of well-advanced demonstrations and the extraordinary potential developments, a significant optimization work is still due to deserve large-scale applications with all necessary validations. Graphical Abstract Aptamer-protein complexes by X-ray crystallography.

Assessment of representativity of the PETALE experiments for validation of Swiss LWRs ex-core dosimetry calculations

The international experimental program PETALE will be carried out at the CROCUS research reactor of EPFL. The program aims at measuring neutron penetration in slabs made of materials composing typical LWR reactor pressure vessel. The measurements will be used for code and nuclear data validation and for the evaluation of the reflecting properties of these materials. In this paper the representativity of the PETALE experiments is assessed with respect to operational LWR reactors dosimetry and activation evaluations using the Paul Scherrer Institute (PSI) in-house tool NUSS. The NUSS tool allows the stochastic sampling of nuclear data using covariance matrices available in modern nuclear data libraries and the subsequent running of a Monte Carlo code with the modified data files. The representativity can then be assessed based on the Pearson correlation coefficients. The ultimate goal of the work is first of all to assess if the planned PETALE measurements could be applicable beyond their primary purpose and serve for extending the PSI validation database for LWR reactor dosimetry evaluations. Secondly, provided that the PETALE measurements are found useful for the task above, the information on the correlations between the PETALE neutron detectors’ responses and the reactor dosimetry quantities of interest, shall be presented and discussed.

An Experimental Programme optimized with Uncertainty Propagation: PETALE in the CROCUS Reactor

The PETALE experimental programme in the CROCUS reactor at EPFL intends to contribute to the validation and improvement of neutron nuclear data in the MeV energy range for stainless steel, particularly in the prospect of heavy reflector elements of pressurized water reactors. It mainly consists of several transmission experiments: first, through metallic sheets of nuclear-grade stainless steel interleaved with dosimeter foils, and, successively, through its elemental components of interest – iron, nickel, and chromium. The present article describes the study for optimizing the response of the dosimetry experiments to the nuclear data of interest.

Nuclear data correlation between different isotopes via integral information

This paper presents a Bayesian approach based on integral experiments to create correlations between different isotopes which do not appear with differential data. A simple Bayesian set of equations is presented with random nuclear data, similarly to the usual methods applied with differential data. As a consequence, updated nuclear data (cross sections, [see formula in PDF], fission neutron spectra and covariance matrices) are obtained, leading to better integral results. An example for 235U and 238U is proposed taking into account the Bigten criticality benchmark.

Current Mode Neutron Noise Measurements in the Zero Power Reactor CROCUS

The present article is an overview of developments and results regarding neutron noise measurements in current mode at the CROCUS zero power facility. Neutron noise measurements offer a non-invasive method to determine kinetic reactor parameters such as the prompt decay constant at criticality α = βeff / λ, the effective delayed neutron fraction βeff, and the mean generation time λ for code validation efforts. At higher detection rates, i.e. above 2×104 cps in the used configuration at 0.1 W, the previously employed pulse charge amplification electronics with BF3 detectors yielded erroneous results due to dead time effects. Future experimental needs call for higher sensitivity in detectors, higher detection rates or higher reactor powers, and thus a generally more versatile measurement system. We, therefore, explored detectors operated with current mode acquisition electronics to accommodate the need. We approached the matter in two ways:

1) By using the two compensated 10B-coated ionization chambers available in CROCUS as operational monitors. The compensated current signal of these chambers was extracted from coremonitoring output channels.

2) By developing a new current mode amplification station to be used with other available detectors in core. Characteristics and first noise measurements of the new current system are presented. We implemented post-processing of the current signals from 1)and 2) with the APSD/CPSD method to determine α. At two critical states (0.5 and 1.5 W), using the 10B ionization chambers and their CPSD estimate, the prompt decay constant was measured after 1.5 hours to be α=(156.9 ± 4.3) s-1 (1σ). This result is within 1σ of statistical uncertainties of previous experiments and MCNPv5-1.6 predictions using the ENDF/B-7.1 library. The newsystem connected to a CFUL01 fission chamber using the APSDestimate at 100 mW after 33 min yielded α = (160.8 ± 6.3) s-1, also within 1σ agreement.

The improvements to previous neutron noise measurementsinclude shorter measurement durations that can achievecomparable statistical uncertainties and measurements at higherdetection rates.

Direct measurement of the mechanism by which magnesium specifically modifies the mechanical properties of DNA

We examine the effect of physiological cations Na+, K+, Mg2+, and Ca2+ on the mechanical properties of bundles of λ-phage DNA using silicon nanotweezers (SNTs). Integrating SNTs with a microfluidic device allows us to perform titration experiments while measuring the effect in real-time. The results show that only for Mg2+ and in particular, at the intra-nuclear concentration (100 mM), the interaction occurs.

Kinetic analysis and binding studies of a new recombinant human factor VIIa for treatment of haemophilia

INTRODUCTION/AIM

LR769 is a new second-generation recombinant human Factor VIIa (rhFVIIa) developed for haemophilia treatment. We determined enzymatic properties of LR769 and its interaction with antithrombin, tissue factor, platelets and endothelial protein C receptor (EPCR), compared with NovoSevenRT.

METHODS

Kinetic enzyme assays and active site titration were used for enzymatic studies. Surface Plasmon Resonance (SPR) was used for determination of binding constants. Cellular binding was determined for platelets and cultured human umbilical vein endothelial cells (HUVEC).

RESULTS

The dissociation constant (K_d ) for activated platelet binding was in the 1 μm range for both products. At saturation, more LR769 than NovoSevenRT was bound to the platelets. Binding to HUVEC was 25-50% higher for LR769 than for NovoSevenRT. Protein C, soluble EPCR, and anti-EPCR antibody all reduced the binding, indicating specificity for EPCR. LR769 was similar to NovoSevenRT in all kinetic assays. Active site titration demonstrated 0.7 mole of active site/mole of protein. The k_cat /K_m values for activation of FX and FIX with purified recombinant tissue factor and phospholipids were 10.5 s^-1 /0.32 μm and 3.3 s^-1 /0.44 μm respectively. The apparent second-order rate constant for inactivation by human plasma AT was 5.9 ± 0.4 × 10³ m^-1 s^-1 . The K_d values for binding of LR769 to soluble tissue factor and full-length tissue factor were 8.1 nm and 0.9 nm, respectively, and the K_d for binding to soluble EPCR was 41 nm.

CONCLUSION

Overall, LR769 exhibited characteristics similar to NovoSevenRT, but bound EPCR on HUVEC with somewhat higher affinity than NovoSevenRT.

3D-shape recognition and size measurement of irregular rough particles using multi-views interferometric out-of-focus imaging

We realize simplified-tomography experiments on irregular rough particles using interferometric out-of-focus imaging. Using two angles of view, we determine the global 3D-shape, the dimensions, and the 3D-orientation of irregular rough particles whose morphologies belong to families such as sticks, plates, and crosses.

Dual-wavelength digital holography for 3D particle image velocimetry: experimental validation

A multi-exposure digital in-line hologram of a particle field is recorded by two successive pulses of different wavelengths. During the reconstruction step, each recording can be independently analyzed by selecting a given wavelength. This procedure enables avoiding the superimposition of particle images that may be close to each other.

In vitro and in vivo properties differ among liquid intravenous immunoglobulin preparations

Objective To compare in vitro and in vivo biological and biochemical properties of five liquid intravenous immunoglobulin (IVIg) preparations licensed for therapeutic use in Europe.

Methods ClairYg® was compared in a blinded manner to four other liquid IVIg preparations licensed in Europe (Octagam®, Kiovig®, Gamunex®, Privigen®). Three batches of each preparation were tested, except for the IgG repertoires and the animal model.

Results Levels of anti-A and anti-B antibodies were lower in ClairYg® (0·11/0·11) relative to a positive EDQM standard and Octagam® (0·11/0·08) than in other preparations (0·33–0·69/0·42–0·46). IgG in ClairYg® recognized 365 and 416 protein spots in HEp-2 cell and Escherichia coli protein extracts vs. 230–330 and 402–842 protein spots, respectively, for IgG in other preparations. IgA content (301 vs. 165–820 ng/mg of IgG), Factor XI and Factor XII antigen (0·46 vs. 0·85–2·40 mU/mg of IgG and 7·8 vs. 20·0–46·2 lU/mg of IgG) C1q binding (0·42 vs. 0·67–1·89 arbitrary units) and C5a uptake (0·41 vs. 0·45–0·66% of activation) were lower in ClairYg® than in other preparations. Finally, intravenous infusion of ClairYg®, Gamunex® and Privigen® had no major effect on arterial blood pressure in spontaneously hypertensive rats.

Conclusions Our results evidence some differences in the biological and biochemical properties among licensed liquid IVIg preparations.

Does microsatellite instability predict the effect of adjuvant chemotherapy in stage III colorectal cancer? A meta-analysis

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Background: Microsatellite instability (MSI) is a prognostic factor in colorectal cancer. Whether it predicts the effect of adjuvant chemotherapy (CT) on overall survival (OS) and relapse-free survival (RFS) is controversial. Methods: Studies were identified by an electronic search using online PubMed, with simultaneous keywords (colorectal neoplasm, microsatellite instability, chemotherapy, prognosis). Abstracts from ASCO and AACR proceedings were reviewed. Articles were obtained from cross-checking of references and from a previous prognostic meta-analysis (MA) (Popat, 2005). We used EasyMA software, available online. A Hazard Ratio (HR) < 1 for MSI-high (MSI-H) status compared with microsatellite stable (MSS) meant a better survival. Results: Our MA found 21 studies (4 abstracts). Statistical calculations were performed in 11 studies (5087 patients including 2879 receiving 5FU-based CT; mean age: 63 years; 1489 stage II, 2648 stage III (64%)). MSI-H was found in 644 patients (15% of total), MSS in 3624. Seven studies (2 randomized) assessed 2 cohorts receiving or not adjuvant CT, 4 studies only included patients receiving CT. Global HR OS (9 studies) was 0.79 (95% confidence interval or CI: 0.64–0.98; p = 0.03). Global HR RFS (8 studies) was 0.67 (95% CI: 0.54–0.83; p < 0.001). A MA on stage III patients (4 studies, 719 patients, 137 MSI-H) found a higher survival among MSI-H than MSS patients receiving CT (HR OS: 0.71, 95% CI 0.49–1.03; HR RFS 0.56, 95% CI 0.42–0.75). Interaction between MSI status and CT status was statistically significant on OS and RFS (4 studies). A MA among MSI-H patients (7 studies) found no survival difference between patients under CT or not: HR OS: 0.70 (95% CI 0.44–1.09), HR RFS: 0.96 (95% CI: 0.62–1.49). Conclusions: Adjuvant CT significantly improved survival in MSI-H compared with MSS patients. MSI-H stage III patients receiving CT survived more than MSS. MSI-H status did not predict response to CT compared with no treatment.

No significant financial relationships to disclose.

A study on associations between PrP genotypes and meat traits in French sheep breeds

In this study the potential association of PrP genotypes with meat traits has been investigated. The data included young rams from individual testing stations of three breeds: Ile de France, Préalpes du Sud and Blanc du Massif Central. These breeds were chosen due to their large number of available animals (with performance records and PrP genotypes) and their differential ARR haplotype frequency. Two analyses differing in the PrP genotype classes considered were carried out. Firstly, animals were categorized into three classes: ARR homozygous, ARR heterozygous, and animals without the ARR haplotype. The data for this analysis included 725, 534 and 832 animals for Ile de France, Préalpes du Sud and Blanc du Massif Central breeds, respectively. Secondly, as the two predominant haplotypes in these breeds are ARR and AR- (and AR- includes ARQ and ARH haplotypes), the effect of substituting 1 or 2 ARR haplotypes for AR- haplotypes was studied. These comparisons involved three genotype classes: ARR homozygous, ARR/AR-, and AR-homozygous. The data for this analysis included 532, 509 and 620 animals of Ile de France, Préalpes du Sud and Blanc du Massif Central breeds, respectively. Meat traits were analysed using an animal model (where the PrP genotype was included as a fixed effect) and they included growth rate, ultrasonic fat depth, and ultrasonic muscle depth. The results of this study indicate no evidence of association between PrP genotypes and the meat traits studied in these sheep breeds.

Sudden, unexpected death due to undiagnosed frontal glioblastoma in a schizophrenic patient

The incidence of sudden death due to undiagnosed primary intracranial tumor is low in forensic autopsy. We report a case of a 48-year-old white male, known to be a schizophrenic patient for several years, and in whom a medico-legal autopsy disclosed a large, previously undiagnosed, bilateral frontal glioblastoma infiltrating the genu of corpus callosum. We emphasize the importance of performing complete autopsy, including a thorough neuropathological examination, in all cases of sudden unexpected death, especially in those cases in which no extracerebral cause of death had been established and whose clinical history was primarily of a psychiatric nature.

Integrative analysis of gene expression patterns predicts specific modulations of defined cell functions by estrogen and tamoxifen in MCF7 breast cancer cells

To explore the mechanisms whereby estrogen and antiestrogen (tamoxifen (TAM)) can regulate breast cancer cell growth, we investigated gene expression changes in MCF7 cells treated with 17beta-estradiol (E2) and/or with 4-OH-TAM. The patterns of differential expression were determined by the ValiGen Gene IDentification (VGID) process, a subtractive hybridization approach combined with microarray validation screening. Their possible biologic consequences were evaluated by integrative data analysis. Over 1000 cDNA inserts were isolated and subsequently cloned, sequenced and analyzed against nucleotide and protein databases (NT/NR/EST) with BLAST software. We revealed that E2 induced differential expression of 279 known and 28 unknown sequences, whereas TAM affected the expression of 286 known and 14 unknown sequences. Integrative data analysis singled out a set of 32 differentially expressed genes apparently involved in broad cellular mechanisms. The presence of E2 modulated the expression patterns of 23 genes involved in anchors and junction remodeling; extracellular matrix (ECM) degradation; cell cycle progression, including G1/S check point and S-phase regulation; and synthesis of genotoxic metabolites. In tumor cells, these four mechanisms are associated with the acquisition of a motile and invasive phenotype. TAM partly reversed the E2-induced differential expression patterns and consequently restored most of the biologic functions deregulated by E2, except the mechanisms associated with cell cycle progression. Furthermore, we found that TAM affects the expression of nine additional genes associated with cytoskeletal remodeling, DNA repair, active estrogen receptor formation and growth factor synthesis, and mitogenic pathways. These modulatory effects of E2 and TAM upon the gene expression patterns identified here could explain some of the mechanisms associated with the acquisition of a more aggressive phenotype by breast cancer cells, such as E2-independent growth and TAM resistance.

Carboxymethyl benzylamide dextran inhibits angiogenesis and growth of VEGF-overexpressing human epidermoid carcinoma xenograft in nude mice

Vascular endothelial growth factor (VEGF) expression is elevated in a wide variety of solid tumours. Inhibition of VEGF activities is able to reduce angiogenesis and tumour growth. We have recently shown in vitro that carboxymethyl dextran benzylamide (CMDB7) prevents the binding of VEGF(165) to its cell surface receptors and thus inhibits VEGF activities on endothelial cells. In the present study, we explored the effects of CMDB7 on highly aggressive human epidermoid carcinoma A431 cells known to overexpress epidermal growth factor receptors (EGFRs) and produce a high amount of VEGF and a minor quantity of bFGF. In vitro, CMDB7 blocked the mitogenic activity of A431-conditioned medium on endothelial cells. Concerning A431 cells, CMDB7 inhibited their proliferation and the VEGF(165) binding to them. In vivo, administration of CMDB7 (10 mg kg(-1)) three times per week for 2 weeks inhibited the growth of A431 xenografts in nude mice by 73% as compared to the control group. Immunostaining of endothelial cells with mouse-specific GSL-1 lectin in tumour sections revealed that CMDB7 also inhibited the density of intratumour endothelial cells by 66%. These findings demonstrate that CMDB7 has an efficient antiangiogenic and antitumour action in vivo even when tumour cells produce a high level of VEGF and EGFRs.

Vascular endothelial growth factor 165 (VEGF(165)) activities are inhibited by carboxymethyl benzylamide dextran that competes for heparin binding to VEGF(165) and VEGF(165).KDR Complexes

We have previously shown that carboxymethyl dextran benzylamide (CMDB7), a heparin-like molecule, inhibits the growth of tumors xenografted in nude mice, angiogenesis, and metastasis by altering the binding of angiogenic growth factors, including platelet-derived growth factor, transforming growth factor beta, and fibroblast growth factor 2, to their specific receptors. In this study, we explore the effect of CMDB7 on the most specific angiogenic growth factor, vascular endothelial growth factor 165 (VEGF(165)). We demonstrate here that CMDB7 inhibits the mitogenic effect of VEGF(165) on human umbilical vein endothelial cells (HUV-ECs) by preventing the VEGF(165)-induced VEGF receptor-2 (KDR) autophosphorylation and consequently a specific intracellular signaling. In competition experiments, the binding of (125)I-VEGF(165) to HUV-ECs is inhibited by CMDB7 with an IC(50) of 2 microm. Accordingly, CMDB7 inhibits the cross-linking of (125)I-VEGF(165) to the surface of HUV-ECs, causing the disappearance of both labeled complexes, 170-180 and 240-250 kDa. We show that CMDB7 increases the electrophoretic mobility of VEGF(165), thus evidencing formation of a stable complex with this factor. Moreover, CMDB7 reduces the (125)I-VEGF(165) binding to coated heparin-albumin and prevents a heparin-induced increase in iodinated VEGF(165) binding to soluble (125)I-KDR-Fc chimera. Concerning KDR, CMDB7 has no effect on (125)I-KDR-Fc electrophoretic migration and does not affect labeled KDR-Fc binding to coated heparin-albumin. In the presence of VEGF(165), (125)I-KDR-Fc binding to heparin is enhanced, and under these conditions, CMDB7 interferes with KDR binding. These data indicate that CMDB7 effectively inhibits the VEGF(165) activities by interfering with heparin binding to VEGF(165) and VEGF(165).KDR complexes but not by direct interactions with KDR.

Sodium phenylacetate enhances the inhibitory effect of dextran derivative on breast cancer cell growth in vitro and in nude mice

Sodium phenylacetate (NaPa) and carboxymethyl benzylamide dextran derivative (CMDB(LS4)) are able to inhibit growth of breast tumour cells. In this study, we explored whether the combination of NaPa and CMDB(LS4)may enhance their respective inhibitory effects on the MCF-7ras cell growth in vitro and in vivo. NaPa inhibited MCF-7ras cell proliferation by reducing the DNA replication concomitantly with a recruitment of cells in G0/G1 phase and by inducing apoptosis in a dose- and time-dependent manner. The addition of CMDB(LS4)potentiated the NaPa antiproliferative effect in the manner dependent on the ratio of CMDB(LS4)and NaPa concentrations. In nude mice, CMDB(LS4)(150 mg kg(-1)) or NaPa (40 mg kg(-1)) administrated twice a week, for 7 weeks inhibited MCF-7ras xenograft growth by 40% and 60%, respectively. The treatment by both, CMDB(LS4)and NaPa, decreased tumour growth by 83% without any toxicity. To better understand the mechanism of NaPa and CMDB(LS4)action we assessed their effect on mitogenic activity of MCF-7ras conditioned medium (CM) on BALBC/3T3 fibroblasts. CMDB(LS4)added to the CM, inhibited its mitogenic activity whereas NaPa had an anti-mitogenic effect when CM was prepared from MCF-7ras cells pretreated with NaPa. Thus, the antiproliferative effects of NaPa and CMDB(LS4)involve 2 different mechanisms explaining, at least in part, the possible synergism between them. Overall, this study points to the potential use of a combination of dextran derivatives with NaPa to inhibit the breast tumour growth.

Lethal methadone intoxications in Geneva, Switzerland, from 1994 to 1998

AIMS

To estimate the number of methadone lethal intoxications in Geneva from 1994 to 1998, where the number of patients in methadone treatment has more than doubled since 1990.

DESIGN

Retrospective study of all toxicological, autopsy and clinical data.

SETTING

The Geneva Department of Forensic Medicine.

PARTICIPANTS

All suspected overdose deaths in Geneva from 1994 to 1998. Cases were selected on the basis that the only cause of death was a potentially lethal drug concentration in the postmortem blood sample.

MEASUREMENT

Toxicology and autopsy findings, clinical and drug history.

FINDINGS

There were 106 lethal drug intoxications over the period. The overall number of drug intoxication deaths went from 33 in 1994 to nine in 1998. Thirty-six cases had methadone identified in their blood. All the 36 cases but one had medications or other drugs used illicitly present in the blood or urine. Of these 36 cases, 21 were attributed to methadone lethal intoxication. Only seven of these 21 decedents were enrolled in a methadone programmes. The number of deaths attributed to methadone intoxication ranged from three to five per year.

CONCLUSION

Most lethal methadone intoxication is due to diverted or illegal methadone in association with medications or other drugs used illicitly. Furthermore, the increase in methadone prescription under strict medical control with health measures aimed at drug abuse prevention did not lead, in our study, to an increase of methadone lethal intoxication and may have been partly responsible for the large decrease of overall drug intoxication deaths during the time of our study.

[Hemodynamic consequences of endogenous hyperinsulinism in obese rats with lesions of the ventromedial hypothalamus]

The rat with ventromedian hypothalamus lesions (VMH) is characterized by massive obesity, hyperinsulinemia, increase in parasympathetic tonus and sympathetic depression. The aim of this study was to examine in this model the hemodynamic changes and the baroreflex response and to compare the data with the evaluation of beta adrenergic sensitivity. In VMH rats and Sham operated rats hemodynamic parameters were followed until 8 weeks after operation. Heart rate (HR) and blood pressure (BP) were monitored each week during 24 hours by a telemetric system, a catheter being implanted in aorta. In VMH, HR was significantly lower by the first week (p = 0.02) and until the last measurement. Systolic BP increased progressively in the two groups but was higher in VMH only at 8 weeks (p = 0.03). Compared with Sham rats, 5 days after operation, the percentage of HR acceleration in response to atropine and isoprenaline was significantly higher in VMH, whereas HR response to sodium nitroprussiate was similar in the two groups. Plasma epinephrine and norepinephrine levels were significantly higher in VMH rats. The density of cardiac beta receptors decreased from 15 days to 3 months after operation, similarly in VMH and Sham rats. The affinity of cardiac beta receptors remained stable during the same period and very similar in VMH and Sham rats. This study suggests that in VMH rats 1. bradycardia results mainly from an increase in parasympathetic tone; 2. the increase in reflex tachycardia described in normal rats after insulin infusion needs a normal activity of the sympathetic nervous system; 3. catecholamine levels may be increased despite sympathetic depression, probably as a result of an increase in adrenomedullary secretion possibly due to endogenous hyperinsulinemia; 4. the lack of hypertension in this model including a massive obesity is likely to result from the proper vasodilatory effect of insulin.

[Forensic medicine experiences with methadone substitution in the Geneva canton]

Methadone treatment for heroin addiction has followed three distinct periods in Geneva, Switzerland. The first period (1970-1979) corresponds to the beginning of the heroin addiction epidemic. Treatment was restricted to detoxification and did not succeed in reducing fatal overdoses. During the second period (1980-1989), methadone maintenance program was favoured but access to this program was limited. This period has brought a decrease of illegal heroin consumption and criminality but not of fatal overdoses. Finally, during the third period (since 1990), legislation was changed to allow easier access to methadone maintenance program. As a consequence there was a significant drop in lethal heroin overdoses and in deaths attributed to HIV.

Identification of a peptide blocking vascular endothelial growth factor (VEGF)-mediated angiogenesis

Vascular endothelial growth factor (VEGF) binding to the kinase domain receptor (KDR/FLK1 or VEGFR-2) mediates vascularization and tumor-induced angiogenesis. Since there is evidence that KDR plays an important role in tumor angiogenesis, we sought to identify peptides able to block the VEGF-KDR interaction. A phage epitope library was screened by affinity for membrane-expressed KDR or for an anti-VEGF neutralizing monoclonal antibody. Both strategies led to the isolation of peptides binding KDR specifically, but those isolated by KDR binding tended to display lower reactivities. Of the synthetic peptides corresponding to selected clones tested to determine their inhibitory activity, ATWLPPR completely abolished VEGF binding to cell-displayed KDR. In vitro, this effect led to the inhibition of the VEGF-mediated proliferation of human vascular endothelial cells, in a dose-dependent and endothelial cell type-specific manner. Moreover, in vivo, ATWLPPR totally abolished VEGF-induced angiogenesis in a rabbit corneal model. Taken together, these data demonstrate that ATWLPPR is an effective antagonist of VEGF binding, and suggest that this peptide may be a potent inhibitor of tumor angiogenesis and metastasis.

[L-tryptophan plasma levels in treatment resistant depressive states]

10 to 30% of depressions are resistant to standard treatment. Different therapeutic strategies are used to treat the resistant depressions. Therefore, before initiating an antidepressant treatment, it would be important to know which patients will probably not respond to a standard treatment. Numerous studies have shown that serotonin is involved in depressive illness and its synthesis in the brain is dependent on the availability of tryprophan from plasma. As tryptophan plasma level is decreased in depression, resistant depressions may also be characterized by alterations of tryptophan plasma level. 141 depressed patients were admitted in our psychiatric unit in Geneva between 1984 and 1990. 36 were diagnosed as treatment resistant depression. Although treatment resistant patients group had more women and a more severe score of depression on the AMDP-4 scale, we did not observe a significant difference in tryptophan plasma level compared to patients who respond to treatment.