Label-free cytotoxicity screening assay by digital holographic microscopy.

Abstract We introduce a label-free technology based on digital holographic microscopy (DHM) with applicability for screening by imaging, and we demonstrate its capability for cytotoxicity assessment using mammalian living cells. For this first high content screening compatible application, we automatized a digital holographic microscope for image acquisition of cells using commercially available 96-well plates. Data generated through both label-free DHM imaging and fluorescence-based methods were in good agreement for cell viability identification and a Z'-factor close to 0.9 was determined, validating the robustness of DHM assay for phenotypic screening. Further, an excellent correlation was obtained between experimental cytotoxicity dose-response curves and known IC values for different toxic compounds. For comparable results, DHM has the major advantages of being label free and close to an order of magnitude faster than automated standard fluorescence microscopy.

Rapid sample pre-treatment prior to GC-MS and GC-MS/MS urinary toxicological screening.

Drug screening is an important issue in clinical and forensic toxicology. Gas chromatography coupled to mass spectrometry (GC-MS) remains the gold standard technique for the screening of unknown compounds in urine samples. However, this technique requires substantial sample preparation, which is time consuming. Moreover, some common drugs such as cannabis cannot be easily detected in urine using general procedures. In this work, a sample preparation protocol for treating 200 μL of urine in less than 30 min is described. The enzymatic hydrolysis of glucuro-conjugates was performed in 5 min thanks to the use of microwaves. The use of a deconvolution software allowed reducing the GC-MS run to 10 min, without impairing the quality of the compound identifications. Comparing the results from 139 authentic urine samples to those obtained using the current routine analysis indicated this method performed well. Moreover, additional 5-min GC-MS/MS programs are described, enabling a very sensitive target screening of 54 drugs, including THC-COOH or buprenorphine, without further sample preparation. These methods appeared as an interesting alternative to immuno-assays based screening. The analytical strategy presented in this article proved to be a promising approach for systematic toxicological analysis (STA) of drugs in urine.

Which anatomical sites should be sampled for screening of methicillin-resistant Staphylococcus aureus carriage by culture or by rapid PCR test?

The nose is the anatomical site usually recommended for methicillin-resistant Staphylococcus aureus (MRSA) screening. Other sites are also recommended, but are more controversial. We showed that the sensitivities of MRSA detection from nasal swabs alone were 48% and 62% by culture or by rapid PCR test, respectively. These percentages increased to 79% and 92% with the addition of groin swabs, and to 96% and 99% with the addition of groin and throat swabs. In conclusion, neither by culture nor by rapid PCR test is nose sampling alone sufficient for MRSA detection. Additional anatomical sites should include at least the groin and throat.

Dépistage de l'athérosclérose: point de la situation en 2006. [Screening for atherosclerosis: 2006 update].

In recent years, several screening tests for subclinical atherosclerosis have been developed. The aim of these tests is to be able to better target preventive therapies to patients at high cardiovascular risk. However, the validity of these screening tests has not been well established for wide use in clinical practice. Being aware of these tests results might also enhance patient motivation to change unhealthy behaviors, such as smoking. However, the effectiveness of such strategy has been poorly studied. Early therapy of atherosclerosis has not been shown to improve clinical outcomes yet. Moreover, potential harms of such screening, such as induced anxiety, have been poorly studied. Although promising, such screening should be validated by clinical trials before routine use in clinical practice.

Prevalence and risk of Down syndrome in monozygotic and dizygotic multiple pregnancies in Europe: implications for prenatal screening.

OBJECTIVE: To determine risk of Down syndrome (DS) in multiple relative to singleton pregnancies, and compare prenatal diagnosis rates and pregnancy outcome. DESIGN: Population-based prevalence study based on EUROCAT congenital anomaly registries. SETTING: Eight European countries. POPULATION: 14.8 million births 1990-2009; 2.89% multiple births. METHODS: DS cases included livebirths, fetal deaths from 20 weeks, and terminations of pregnancy for fetal anomaly (TOPFA). Zygosity is inferred from like/unlike sex for birth denominators, and from concordance for DS cases. MAIN OUTCOME MEASURES: Relative risk (RR) of DS per fetus/baby from multiple versus singleton pregnancies and per pregnancy in monozygotic/dizygotic versus singleton pregnancies. Proportion of prenatally diagnosed and pregnancy outcome. STATISTICAL ANALYSIS: Poisson and logistic regression stratified for maternal age, country and time. RESULTS: Overall, the adjusted (adj) RR of DS for fetus/babies from multiple versus singleton pregnancies was 0.58 (95% CI 0.53-0.62), similar for all maternal ages except for mothers over 44, for whom it was considerably lower. In 8.7% of twin pairs affected by DS, both co-twins were diagnosed with the condition. The adjRR of DS for monozygotic versus singleton pregnancies was 0.34 (95% CI 0.25-0.44) and for dizygotic versus singleton pregnancies 1.34 (95% CI 1.23-1.46). DS fetuses from multiple births were less likely to be prenatally diagnosed than singletons (adjOR 0.62 [95% CI 0.50-0.78]) and following diagnosis less likely to be TOPFA (adjOR 0.40 [95% CI 0.27-0.59]). CONCLUSIONS: The risk of DS per fetus/baby is lower in multiple than singleton pregnancies. These estimates can be used for genetic counselling and prenatal screening.

Concentrations sériques de protéines placentaires au 1er trimestre dans des grossesses monofoetales et multiples après FIV : implications pour le dépistage de la trisomie 21 [First trimester serum concentrations of placental proteins in singleton and multiple IVF pregnancies: implications for Down syndrome screening]

First trimester biochemical trisomy screening is based on serum concentrations of pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotrophin (hCG). Our aim was to confirm previously suggested modifications in serum marker concentrations after in vitro fertilisation (IVF) and embryo transfer (ET), and to assess the need of establishing normal medians for trisomy screening in these. We compared 56 singleton pregnancies obtained after ET (of which 40 in gonadotrophin stimulation cycles) with 120 gestation-matched spontaneous controls. For multiple pregnancies, 17 treated cycles were compared with 25 controls. The levels of PAPP-A, hCG, and pregnancy-specific β1-glycoprotein were determined and compared between treated and spontaneous pregnancies. Serum PAPP-A levels were reduced in pregnancies achieved after gonadotrophin-stimulated IVF and ET, and this was more pronounced in earlier gestational stages. SP1 followed the same trend, while hCG tended to be increased, and this not only in pregnancies obtained from gonadotrophin-stimulated but also from oestrogen supported cycles, and with a more pronounced effect in the later gestational ages examined here. Decreased PAPP-A together with increased hCG concentrations produce falsely elevated results in first trimester Down syndrome screening, but we do not recommend the establishment of normal medians for IVF pregnancies due to the variations in stimulation protocols.

Fast analysis of doping agents in urine by ultra-high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry I. Screening analysis.

The general strategy to perform anti-doping analyses of urine samples starts with the screening for a wide range of compounds. This step should be fast, generic and able to detect any sample that may contain a prohibited substance while avoiding false negatives and reducing false positive results. The experiments presented in this work were based on ultra-high-pressure liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry. Thanks to the high sensitivity of the method, urine samples could be diluted 2-fold prior to injection. One hundred and three forbidden substances from various classes (such as stimulants, diuretics, narcotics, anti-estrogens) were analysed on a C(18) reversed-phase column in two gradients of 9min (including two 3min equilibration periods) for positive and negative electrospray ionisation and detected in the MS full scan mode. The automatic identification of analytes was based on retention time and mass accuracy, with an automated tool for peak picking. The method was validated according to the International Standard for Laboratories described in the World Anti-Doping Code and was selective enough to comply with the World Anti-Doping Agency recommendations. In addition, the matrix effect on MS response was measured on all investigated analytes spiked in urine samples. The limits of detection ranged from 1 to 500ng/mL, allowing the identification of all tested compounds in urine. When a sample was reported positive during the screening, a fast additional pre-confirmatory step was performed to reduce the number of confirmatory analyses.

Venture capital financing : screening and contracting under assymetric information

Structure of the Thesis This thesis consists of 5 sections. Section 1 starts with the problem definition and the presentation of the objectives of this thesis. Section 2 introduces a presentation of the theoretical foundations of Venture financing and a review of the main theories developed on Venture investing. It includes a taxonomy of contracting clauses relevant in venture contracting, the conflicts they address, and presents some general observations on contractual clauses. Section 3 presents the research findings on the analysis of a European VC's deal flow and investment screening linked to the prevailing market conditions. Section 4 focuses an empirical study of a European VC's investment process, the criteria it uses to make its investments. It presents empirical findings on the investment criteria over time, business cycles, and investment types. It also links these criteria to the VC's subsequent performance. Finally, section 5 presents an empirical research on the comparison of the legal contracts signed between European and United States Venture Capitalists and the companies they finance. This research highlights some of the contracting practices in Europe and the United States.

Platforms for high-throughput screening of Wnt/Frizzled antagonists.

Signaling cascades initiated by Wnt lipoglycoproteins and their receptors of the Frizzled family regulate many aspects of animal development and physiology. Improper activation of this signaling promotes carcinogenic transformation and metastasis. Development of agents blocking the Wnt-Frizzled signaling is of prime interest for drug discovery. Despite certain progress no such agents are as yet brought to the market or even to clinical trials. One reason for these delays might be the use of suboptimal readout assays. In this article we overview existing and developing assay platforms to screen for Wnt-Frizzled antagonists. Among those, G protein-activating assays built on the emerging GPCR properties of Frizzleds are highlighted.

Measuring potentially avoidable hospital readmissions.

The objectives of this study were to develop a computerized method to screen for potentially avoidable hospital readmissions using routinely collected data and a prediction model to adjust rates for case mix. We studied hospital information system data of a random sample of 3,474 inpatients discharged alive in 1997 from a university hospital and medical records of those (1,115) readmitted within 1 year. The gold standard was set on the basis of the hospital data and medical records: all readmissions were classified as foreseen readmissions, unforeseen readmissions for a new affection, or unforeseen readmissions for a previously known affection. The latter category was submitted to a systematic medical record review to identify the main cause of readmission. Potentially avoidable readmissions were defined as a subgroup of unforeseen readmissions for a previously known affection occurring within an appropriate interval, set to maximize the chance of detecting avoidable readmissions. The computerized screening algorithm was strictly based on routine statistics: diagnosis and procedures coding and admission mode. The prediction was based on a Poisson regression model. There were 454 (13.1%) unforeseen readmissions for a previously known affection within 1 year. Fifty-nine readmissions (1.7%) were judged avoidable, most of them occurring within 1 month, which was the interval used to define potentially avoidable readmissions (n = 174, 5.0%). The intra-sample sensitivity and specificity of the screening algorithm both reached approximately 96%. Higher risk for potentially avoidable readmission was associated with previous hospitalizations, high comorbidity index, and long length of stay; lower risk was associated with surgery and delivery. The model offers satisfactory predictive performance and a good medical plausibility. The proposed measure could be used as an indicator of inpatient care outcome. However, the instrument should be validated using other sets of data from various hospitals.

Phenotip - a web-based instrument to help diagnosing fetal syndromes antenatally.

Prenatal ultrasound can often reliably distinguish fetal anatomic anomalies, particularly in the hands of an experienced ultrasonographer. Given the large number of existing syndromes and the significant overlap in prenatal findings, antenatal differentiation for syndrome diagnosis is difficult. We constructed a hierarchic tree of 1140 sonographic markers and submarkers, organized per organ system. Subsequently, a database of prenatally diagnosable syndromes was built. An internet-based search engine was then designed to search the syndrome database based on a single or multiple sonographic markers. Future developments will include a database with magnetic resonance imaging findings as well as further refinements in the search engine to allow prioritization based on incidence of syndromes and markers.