Improved NGS-based detection of microsatellite instability using tumor-only data

Microsatellite instability (MSI) is a molecular signature of mismatch repair deficiency (dMMR), a predictive marker of immune checkpoint inhibitor therapy response. Despite its recognized pan-cancer value, most methods only support detection of this signature in colorectal cancer. In addition to the tissue-specific differences that impact the sensitivity of MSI detection in other tissues, the performance of most methods is also affected by patient ethnicity, tumor content, and other sample-specific properties. These limitations are particularly important when only tumor samples are available and restrict the performance and adoption of MSI testing. Here we introduce MSIdetect, a novel solution for NGS-based MSI detection. MSIdetect models the impact of indel burden and tumor content on read coverage at a set of homopolymer regions that we found are minimally impacted by sample-specific factors. We validated MSIdetect in 139 Formalin-Fixed Paraffin-Embedded (FFPE) clinical samples from colorectal and endometrial cancer as well as other more challenging tumor types, such as glioma or sebaceous adenoma or carcinoma. Based on analysis of these samples, MSIdetect displays 100% specificity and 96.3% sensitivity. Limit of detection analysis supports that MSIdetect is sensitive even in samples with relatively low tumor content and limited microsatellite instability. Finally, the results obtained using MSIdetect in tumor-only data correlate well (R=0.988) with what is obtained using tumor-normal matched pairs, demonstrating that the solution addresses the challenges posed by MSI detection from tumor-only data. The accuracy of MSI detection by MSIdetect in different cancer types coupled with the flexibility afforded by NGS-based testing will support the adoption of MSI testing in the clinical setting and increase the number of patients identified that are likely to benefit from immune checkpoint inhibitor therapy.

Social and physical neighbourhood characteristics and loneliness among older adults: results from the MINDMAP project

BACKGROUND

Loneliness is associated with several adverse mental and physical health outcomes in older adults. Previous studies have shown that a variety of individual-level and perceived area-level characteristics are associated with loneliness. This study examined the associations of objectively measured social and physical neighbourhood characteristics with loneliness.

METHODS

We used cross-sectional data from 1959 older adults (63-98 years) who participated in the Longitudinal Ageing Study Amsterdam (LASA; wave 2011/12) and the Health and Living Conditions of the Population of Eindhoven and Surroundings study (GLOBE; wave 2014) in the Netherlands. Study-specific loneliness scores were harmonised across both cohort studies and divided into tertiles denoting low, medium and high levels of loneliness. Objectively measured neighbourhood characteristics, including area-level percentages of low educated residents, social security beneficiaries and unoccupied dwellings, average income, crime levels and land use mix, were linked to individual-level data. Multinomial logistic regression analyses were conducted to examine the associations of interest.

RESULTS

There was no statistical evidence for an association of the included neighbourhood characteristics with loneliness. Although not statistically significant, the observed associations suggested that participants living in neighbourhoods with more heterogeneous land use mix were less likely to have a medium and high level of loneliness than those living in more homogeneous neighbourhoods in terms of land use mix (ORmedium=0.54, 95% CI=0.18-1.67; ORhigh=0.67, 95% CI=0.21-2.11).

CONCLUSION

The results indicate that the included objectively measured social and physical neighbourhood characteristics are not associated with loneliness in old age.

Overview of retrospective data harmonisation in the MINDMAP project: process and results

Background

The MINDMAP project implemented a multinational data infrastructure to investigate the direct and interactive effects of urban environments and individual determinants of mental well-being and cognitive function in ageing populations. Using a rigorous process involving multiple teams of experts, longitudinal data from six cohort studies were harmonised to serve MINDMAP objectives. This article documents the retrospective data harmonisation process achieved based on the Maelstrom Research approach and provides a descriptive analysis of the harmonised data generated.

Methods

A list of core variables (the DataSchema) to be generated across cohorts was first defined, and the potential for cohort-specific data sets to generate the DataSchema variables was assessed. Where relevant, algorithms were developed to process cohort-specific data into DataSchema format, and information to be provided to data users was documented. Procedures and harmonisation decisions were thoroughly documented.

Results

The MINDMAP DataSchema (v2.0, April 2020) comprised a total of 2841 variables (993 on individual determinants and outcomes, 1848 on environmental exposures) distributed across up to seven data collection events. The harmonised data set included 220 621 participants from six cohorts (10 subpopulations). Harmonisation potential, participant distributions and missing values varied across data sets and variable domains.

Conclusion

The MINDMAP project implemented a collaborative and transparent process to generate a rich integrated data set for research in ageing, mental well-being and the urban environment. The harmonised data set supports a range of research activities and will continue to be updated to serve ongoing and future MINDMAP research needs.

Can early neurological improvement after mechanical thrombectomy be used as a surrogate for final stroke outcome?

Background and purpose

We aimed to identify the best definition of early neurological improvement (ENI) at 2 and 24 hours after mechanical thrombectomy (MT) and determine its ability to predict a good functional outcome at 3 months.

Methods

This retrospective analysis was based on a prospectively collected registry of patients treated by MT for ischemic stroke from May 2010 to March 2017. We included patients treated with stent-retrievers with National Institute of Health Stroke Scale (NIHSS) score before treatment and at 2 and/or 24 hours after treatment and modified Rankin Score (mRS) at 3 months. Receiver operating characteristic curve analysis was performed to estimate optimal thresholds for ENI at 2 and 24 hours. The relationship between optimal ENI definitions and good outcome at 3 months (mRS 0–2) was assessed by logistic regression.

Results

The analysis included 246 patients. At 2 hours, the optimal threshold to predict a good outcome at 3 months was improvementin the NIHSS score of >1 point (AUC 0.83,95% CI 0.77 to 0.87), with sensitivity and specificity 78.3% (62.2–85.7%) and 84.6% (77.2–90.3%), respectively, and OR 12.67 (95% CI 4.69 to 31.10, p<0.0001). At 24 hours, the optimal threshold was an improvementin the NIHSS score of >4 points (AUC 0.93, 95% CI 0.89 to 0.96), with sensitivity and specificity 93.8% (87.7–97.5%) and 83.2% (75.7–89.2%), respectively, and OR 391.32 (95% CI 44.43 to 3448.35, p<0.0001).

Conclusions

ENI 24 hours after thrombectomy appears to be a straightforward surrogate of long-term endpoints and may have value in future research.

Atomistic Picture of Fluorescent Probes with Hydrocarbon Tails in Lipid Bilayer Membranes: An Investigation of Selective Affinities and Fluorescent Anisotropies in Different Environmental Phases

By reverting to spectroscopy, changes in the biological environment of a fluorescent probe can be monitored and the presence of various phases of the surrounding lipid bilayer membranes can be detected. However, it is currently not always clear in which phase the probe resides. The well-known orange 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbo-cyanine perchlorate (DiI-C18(5)) fluorophore, for instance, and the new, blue BODIPY (4,4-difluoro-4-bora-3 a,4 a-diaza- s-indacene) derivative were experimentally seen to target and highlight identical parts of giant unilamellar vesicles of various compositions, comprising mixtures of dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), and cholesterol (Chol). However, it was not clear which of the coexisting membrane phases were visualized (Bacalum et al., Langmuir. 2016, 32, 3495). The present study addresses this issue by utilizing large-scale molecular dynamics simulations and the z-constraint method, which allows evaluating Gibbs free-energy profiles. The current calculations give an indication why, at room temperature, both BODIPY and DiI-C18(5) probes prefer the gel (S_o) phase in DOPC/DPPC (2:3 molar ratio) and the liquid-ordered (L_o) phase in DOPC/SM/Chol (1:2:1 molar ratio) mixtures. This study highlights the important differences in orientation and location and therefore in efficiency between the probes when they are used in fluorescence microscopy to screen various lipid bilayer membrane phases. Dependent on the lipid composition, the angle between the transition-state dipole moments of both probes and the normal to the membrane is found to deviate clearly from 90°. It is seen that the DiI-C18(5) probe is located in the headgroup region of the SM/Chol mixture, in close contact with water molecules. A fluorescence anisotropy study also indicates that DiI-C18(5) gives rise to a distinctive behavior in the SM/Chol membrane compared to the other considered membranes. The latter behavior has not been seen for the studied BODIPY probe, which is located deeper in the membrane.

Major histocompatibility complex-linked social signalling affects female fertility

Genes of the major histocompatibility complex (MHC) have been shown to influence social signalling and mate preferences in many species, including humans. First observations suggest that MHC signalling may also affect female fertility. To test this hypothesis, we exposed 191 female horses (Equus caballus) to either an MHC-similar or an MHC-dissimilar stimulus male around the time of ovulation and conception. A within-subject experimental design controlled for non-MHC-linked male characteristics, and instrumental insemination with semen of other males (n = 106) controlled for potential confounding effects of semen or embryo characteristics. We found that females were more likely to become pregnant if exposed to an MHC-dissimilar than to an MHC-similar male, while overall genetic distance to the stimulus males (based on microsatellite markers on 20 chromosomes) had no effect. Our results demonstrate that early pregnancy failures can be due to maternal life-history decisions (cryptic female choice) influenced by MHC-linked social signalling.

Outcome after urgent microvascular revision of free DIEP, SIEA and SGAP flaps for autologous breast reconstruction

INTRODUCTION

Microvascular complications after free flap breast reconstruction are devastating, and revision of a compromised breast reconstruction is very challenging. The aim of this study was to review the different characteristics of urgent microvascular revision in DIEP, SIEA and SGAP flaps and to evaluate the final outcome after revision.

MATERIALS AND METHODS

A retrospective chart review was performed for all patients who underwent an autologous breast reconstruction with a DIEP, SIEA or SGAP flap at the University Hospitals of Leuven between August 1997 and December 2013. The number of revisions, time to revision, reason for revision, and outcome after microvascular free flap revision were analysed.

RESULTS

A total of 1562 free flaps were evaluated during the study period, of which 4.42% required urgent exploration. DIEP flaps (3.38%) had a statistically significant lower revision rate than SIEA flaps (11.76%) and SGAP flaps (8.42%). Venous insufficiency was the main reason for revision of DIEP flaps (86.7%) and SGAP flaps (62.5%). SIEA flaps mostly failed because of an arterial problem (62.5%). SIEA flaps (62.5%) had a higher revision failure rate than DIEP flaps (37.8%) and SGAP flaps (12.5%). We found a statistically significant difference (p < 0.001) in the outcome of revision in DIEP flaps in correlation to the time to revision. Our overall flap failure rate was 1.79% (DIEP 1.28%; SIEA 7.35%; SGAP 1.05%).

CONCLUSIONS

The DIEP flap remains the most reliable flap for microvascular breast reconstructions. SIEA flaps are only performed when no suitable perforator for a DIEP flap is present. Multiple revisions are no longer performed, as the outcome after more than one revision is very disappointing. The difference in reason for revision between the different flaps led to the introduction of some technical refinements.

The ABCG transporter PEC1/ABCG32 is required for the formation of the developing leaf cuticle in Arabidopsis

The cuticle is an essential diffusion barrier on aerial surfaces of land plants whose structural component is the polyester cutin. The PERMEABLE CUTICLE1/ABCG32 (PEC1) transporter is involved in plant cuticle formation in Arabidopsis. The gpat6 pec1 and gpat4 gapt8 pec1 double and triple mutants are characterized. Their PEC1-specific contributions to aliphatic cutin composition and cuticle formation during plant development are revealed by gas chromatography/mass spectrometry and Fourier-transform infrared spectroscopy. The composition of cutin changes during rosette leaf expansion in Arabidopsis. C16:0 monomers are in higher abundance in expanding than in fully expanded leaves. The atypical cutin monomer C18:2 dicarboxylic acid is more prominent in fully expanded leaves. Findings point to differences in the regulation of several pathways of cutin precursor synthesis. PEC1 plays an essential role during expansion of the rosette leaf cuticle. The reduction of C16 monomers in the pec1 mutant during leaf expansion is unlikely to cause permeability of the leaf cuticle because the gpat6 mutant with even fewer C16:0 monomers forms a functional rosette leaf cuticle at all stages of development. PEC1/ABCG32 transport activity affects cutin composition and cuticle structure in a specific and non-redundant fashion.

The Use of Long-term Hepatocyte Cultures for Detecting Induction of Drug Metabolising Enzymes: The Current Status

In this report, metabolically competent in vitro systems have been reviewed, in the context of drug metabolising enzyme induction. Based on the experience of the scientists involved, a thorough survey of the literature on metabolically competent long-term culture models was performed. Following this, a prevalidation proposal for the use of the collagen gel sandwich hepatocyte culture system for drug metabolising enzyme induction was designed, focusing on the induction of the cytochrome P450 enzymes as the principal enzymes of interest. The ultimate goal of this prevalidation proposal is to provide industry and academia with a metabolically competent in vitro alternative for long-term studies. In an initial phase, the prevalidation study will be limited to the investigation of induction. However, proposals for other long-term applications of these systems should be forwarded to the European Centre for the Validation of Alternative Methods for consideration. The prevalidation proposal deals with several issues, including: a) species; b) practical prevalidation methodology; c) enzyme inducers; and d) advantages of working with independent expert laboratories. Since it is preferable to include other alternative tests for drug metabolising enzyme induction, when such tests arise, it is recommended that they meet the same level of development as for the collagen gel sandwich long-term hepatocyte system. Those tests which do so should begin the prevalidation and validation process.

A member of the PLEIOTROPIC DRUG RESISTANCE family of ATP binding cassette transporters is required for the formation of a functional cuticle in Arabidopsis

Although the multilayered structure of the plant cuticle was discovered many years ago, the molecular basis of its formation and the functional relevance of the layers are not understood. Here, we present the permeable cuticle1 (pec1) mutant of Arabidopsis thaliana, which displays features associated with a highly permeable cuticle in several organs. In pec1 flowers, typical cutin monomers, such as ω-hydroxylated fatty acids and 10,16-dihydroxypalmitate, are reduced to 40% of wild-type levels and are accompanied by the appearance of lipidic inclusions within the epidermal cell. The cuticular layer of the cell wall, rather than the cuticle proper, is structurally altered in pec1 petals. Therefore, a significant role for the formation of the diffusion barrier in petals can be attributed to this layer. Thus, pec1 defines a new class of mutants. The phenotypes of the pec1 mutant are caused by the knockout of ATP BINDING CASSETTEG32 (ABCG32), an ABC transporter from the PLEIOTROPIC DRUG RESISTANCE family that is localized at the plasma membrane of epidermal cells in a polar manner toward the surface of the organs. Our results suggest that ABCG32 is involved in the formation of the cuticular layer of the cell wall, most likely by exporting particular cutin precursors from the epidermal cell.

A randomized, double-blind, placebo-controlled study of benfluorex in HIV-infected patients with insulin resistance or impaired glucose tolerance

PURPOSE

We previously reported a beneficial effect of benfluorex (BFL) on oral glucose tolerance test (OGTT) and visceral fat mass in an open-label study conducted in 60 HIV-infected patients. The objective of this study was to assess whether administration of BFL compared to placebo (PBO) improves insulin resistance (IR) in HIV+ patients with HAART- induced lipodystrophy.

METHOD

22 HIV-infected patients with IR or impaired glucose tolerance were double-blind randomly assigned to receive BFL 3 tablets/day or PBO for 24 weeks. Efficacy assessments included OGTT, abdominal computed tomography, and the measurement of fasting lipids.

RESULTS

Change of median insulin AUC was -53.0 microIU/mL (IQR, -126.0 to -12.7) in the BFL group vs. +33.6 microIU/mL (IQR, 7.0 to 115.6) (p = .01) in PBO group. Weight decreased significantly in the BFL group (-2 kg +/- 2.6; IQR, -6.8 to 2.0) compared to the PBO group (0.8 kg +/- 1.7; IQR, -2.0 to 0.5) (p = .02). No significant changes in visceral or subcutaneous fat mass and plasma lipid level were observed between the two groups.

CONCLUSION

Added to antiretroviral therapy, a 6-month therapy with BFL improved insulin sensitivity but is not sufficient to reduce significantly visceral fat mass.

Reconstruction mammaire prothétique après expansion préalable prolongée. À propos de 247 cas

SUBJECT

The purpose of this study was to analyse the complications and the aesthetic results in case of slow tissue expansion in prosthetic breast reconstruction.

PATIENTS AND METHODS

We tracked 237 patients representing 247 mammary reconstructions operated between 1992 and 2004. These patients were distributed in two series, a series of 148 operated mammary reconstructions between 1992 and 2000 and a series of 99 reconstructions operated between 2001 and 2004. For every reconstruction, we analysed the progress of the expansion, the complications and the quality of the aesthetic results according to the radiotherapy and the type of implant used.

RESULTS

The radiotherapy increases the risk of failure of the breast reconstruction and degrades the quality of the aesthetic results. Capsular contractures are rare and their frequency does not depend on the irradiation. Prosthesis infections and exposure are more frequent on irradiated ground.

DISCUSSION

The tissue expansion in prosthetic breast reconstruction is a technique studied well in the literature, but few authors use a chronic expansion and compare the long-term results according to the radiotherapy. If our study confirms the noxious role of the radiotherapy as for the complications and for the aesthetic aspect of the results, it is not a question for us of an absolute contraindication. The weak rate of capsular contracture is attributable to the chronic character of the expansion, which allows the maturation of the capsule. The use of silicone gel implants decreases the deflations but does not improve the results.

CONCLUSIONS

The radiotherapy increases the risks of failure of the tissulaire expansion and decreases the quality of the aesthetic results. The chronic character of the expansion allows to obtain a rate of capsular contracture weak, even on irradiated ground. The silicone gel implants make it possible to obtain a perennial result.

Abdominal aplasia cutis congenita: case report and review of the literature

A case of bilateral abdominal aplasia cutis congenita without skull defect is reported and was treated successfully by a combination of allografts and growth factors delivered by allogenic cultured keratinocytes.

Target-controlled sedation-analgesia using propofol and remifentanil in women undergoing late termination of pregnancy

Twenty-one women undergoing termination of pregnancy for severe fetal abnormality received remifentanil and propofol using a target-controlled infusion system and were studied prospectively. Target concentrations were initially set at 1 ng.mL(-1) for remifentanil and 0.8 microg.mL(-1) for propofol. Remifentanil concentration was adjusted to obtain visual analog scores <50 mm with preservation of ventilation. Visual analog scores assessed by the patients and physiologic data were recorded every 15 min until delivery. The median duration of administration was 150 min [10th-90th centiles: 42-282 min). Visual analog scores decreased within the first 5 min (P < 0.05) and remained under 50 mm for 91.7% of time. The median rate of infusion of remifentanil was 0.056 microg.kg(-1) min(-1) [10th-90th centiles: 0.037-0.15 ng.mL(-1)]. At delivery, the median target concentration was 2.2 ng.mL(-1) [10th-90th centiles: 1.25-4 ng.mL(-1)] for remifentanil and 0.8 microg.mL(-1) [10th-90th centiles: 0.32-1.12 microg.mL(-1)] for propofol. Remifentanil requirements were statistically correlated to gestational age, parity and duration of labor. No episodes of ventilatory depression, nausea, vomiting or pruritus were noted. Patients scored analgesia as excellent in 12 cases, good in 7 cases and moderate in 2 cases. Further studies are required to determine the place and the best regimen of remifentanil infusion for pain management in labor in those cases when epidural analgesia is contraindicated.

Declared hepatitis C screening strategies in blood recipients in French hospitals

AIMS OF THE STUDY

In spite of official recommendations and measures in France, screening strategies of hepatitis C performed in the field of transfusion are not clearly known. The aim of this study is to describe the screening strategies before and after the current year of the transfusion in blood recipients in several French medical departments and hospitals.

MATERIALS AND METHODS

A qualitative study using the key informant technique was carried out. A sample of 179 departments and 64 hospitals in charge of patients transfused with low or high-volumes of homologous blood products was constituted. The key informants were asked about the number of homologous blood products, the number of recipients transfused in the hospital, the volume of transfusion performed, the existence of a single defined screening strategy, the time of prescription of the biological tests (before or after transfusion), the tests performed on cryopreserved blood samples, and the indications of the transfusion.

RESULTS

The main screening strategy was HCV serology (second or third generation of enzyme immunoassays) with transaminase assessments before and after transfusion in 14% of the declared screening strategies. Screening tests were more frequently prescribed after transfusion, in at least 64% of the declared screening strategies according to the volume of transfusion. HCV serology was the common test prescribed in 61 and 50% of the screening strategies for low and high-volume transfusion respectively. The screening strategies showed a large heterogeneity combining HCV serology, transaminase assessment, before or after transfusion.

CONCLUSION

A great heterogeneity of screening strategies was found. The most frequent was HCV serology with transaminase assessment before and after transfusion. Recommendations on screening strategies are needed in order to limit practice heterogeneity. This study will help building a cost-efficacy model in order to guide public health decision making.

[Femoral shaft fractures in the elderly treated by intramedullary nailing]

PURPOSE OF THE STUDY

Little work has been devoted to femoral shaft fractures in the elderly, contrasting with the data available for proximal neck or trochanteric fractures. The purpose of this study was to determine the epidemiological and clinical features of femoral shaft fractures in the elderly from a retrospective series of 58 patients who underwent locked intramedullary nailing procedures with Grosse and Kempf (GK) or long gamma (GL) nails.

MATERIAL AND METHODS

The series included 38 women and 20 men, mean age 83.6 years, who suffered a fracture of the femoral diaphysis due to a fall at home (49 fractures), a traffic accident (8 fractures) or a high-energy fall (1 fracture). Prior to the fracture, 10 patients had homolateral osteoarthritis and two had a contralateral hip arthroplasty. Twenty-six patients were in very good health, 19 had a history of cardiovascular disease, 9 had diabetes and 12 suffered parkinsonian syndromes or dementia. The ASA score was I in 24, II in 23 and III in 11. The diaphyseal fracture was isolated in 31 cases and associated with trochanteric involvement in 27. The upper third of the femur was involved in 37 cases, the middle third in 7 and the lower third in 14. Generally there was a simple spiroid subtrochanteric fracture line (36 cases), or a torsion wedge with or without a proximal extension. Mean delay to surgery was 1.9 days. Subtrochanteric fractures with a proximal line were stabilized with a GL (34 nails) and diaphyseal fractures with a GK (24 nails). Mean duration of the procedure was 1.9 for GL and 2 hours for GK. In 22 cases (17 GL and 5 GK), a minimally invasive access was needed to achieve reduction or stabilization during reaming and insertion of complementary fixation (3 screw fixations, 7 cerclages).

RESULTS

Six patients died before six months, 4 during the initial hospitalization. Twenty patients experienced general complications: 7 cases of phlebitis and 5 "end-of-life" syndromes. Infection occurred in 3 cases including one septic arthritis leading to a bedridden situation. A new fracture beyond the ends of the implant occurred in 2 others. The upright position was achieved within 31 days and total weight bearing within 69 days. Bone fusion was achieved at 4 months (mean). Six patients died between 6 and 12 months, giving a 20.6% mortality at 1 year. Clinical outcome at 12 months was available for 42 living patients: 21 were walking without assistance, 7 used a cane, 8 required crutches or another assistance device and 6 were bedridden.

DISCUSSION

The general and functional prognosis of femoral shaft fractures in the elderly is the same as for proximal fractures. These diaphyseal fractures can be individualized due to their characteristic mechanical and anatomic features: composite fracture with a rotation element involving the distal portion of the trochanter and the proximal quarter of the diaphysis. Several types of ostheosynthesis have been proposed for fixation. Locked intramedullary nailing has been found to be effective despite the difficulty in reduction, especially for particularly proximal fractures. There is a risk of iterative fracture in the transition zones between the femoral component and the osteoporotic bone.

Expression and induction of CYP1A1/1A2, CYP2A6 and CYP3A4 in primary cultures of human hepatocytes: a 10-year follow-up

1. The aims were to refine experimental conditions (using 76 human hepatocyte preparations) in terms of the selection of enzyme inducers and their optimal concentration, the treatment duration with inducers and the choice of specific cytochrome P450 isoform(s) probes to optimize the use of primary hepatocytes for predicting the potential induction by new chemical entities of cytochrome P450 isoforms in vivo in man. 2. In the absence of any inducer, basal cytochrome P450 isoform(s)-mediated activities decreased to 20% of their initial activity (end of the seeding period) by 72-96 h. In contrast, UGT-dependent enzyme activities remained at a constant level (+/- 20%) up to the fifth day of culture. 3. Beta-naphthoflavone, at an optimal concentration of 50 microM and after a 3-day treatment, specifically and potently induced 7-ethoxyresorufin (10.4 +/- 10.4-fold, n = 74) and phenacetin (6.6 +/- 6.4-fold, n = 60) O-deethylation processes, markers for CYP1A1 and CYP1A2 isoforms respectively. Only a 2-fold increase was noted following treatment with 2 mM phenobarbitone, whereas dexamethasone and rifampicin had no effect at all. 4. A 3-day treatment of human hepatocytes with 50 microM dexamethasone was associated with a major induction of both coumarin 7-hydroxylation (9.4 +/- 11.4-fold, n = 49) and nifedipine dehydrogenation (4.7 +/- 3.8-fold, n = 61), markers for CYP2A6 and CYP3A4 respectively. Phenobarbitone, however, exhibited a broad but moderate inducing effect on 7-ethoxyresorufin (2.2 +/- 1.5-fold, n = 55) and phenacetin (1.7 +/- 0.9-fold, n = 54) O-deethylation, coumarin 7-hydroxylation (3.9 +/- 9.2-fold, n = 50) and nifedipine dehydrogenation (2.1 +/- 2.0-fold, n = 47). 5. Km obtained for the different cytochrome P450 isoform substrates in untreated hepatocytes were in the same range of magnitude that those determined on human hepatic microsomal fractions. Enzyme induction processes were characterized by a large increase in apparent Vmax whereas apparent Km were not affected. 6. These studies demonstrate that human hepatocytes in primary culture can respond specifically and quantitatively to model inducers. This in vitro system offers a useful approach to study the regulation of human hepatic biotransformation activities and should facilitate the demand for a reproducible method for addressing cytochrome P450 induction.

[Fall in the seroprevalence of hepatitis A in French youth]

OBJECTIVE

An anti-hepatitis A virus seroprevalence survey was performed in 1997 in 1052 French army recruits (mean age: 21.2 years). To describe epidemiological trends, the current pattern was compared to previous results obtained by similar methods in 1985, 1990 and 1993.

RESULTS

In 1997, overall anti-hepatitis A virus seroprevalence was 11.5%. The greatest risk factor of hepatitis A infection was related to travel in intermediate or highly endemic areas for hepatitis A virus: 46% of overseas residents (odds ratio = 10.3), 28% of recruits who had travelled in developing countries (odds ratio = 3.7) and 7.65% of French living in industrialised countries are anti-hepatitis A virus antibody positive. Moreover, seroprevalence was higher in subjects with a history of icteria (adjusted odds ratio = 3.5) and families with at least 3 children (adjusted odds ratio = 3). No association was found with drinking water, socioeconomic status such as baccalaureat degree, or parents profession. The seroepidemiological shift of hepatitis A, as assessed in three previous studies, shows a marked decrease of 20% in 12 years from 30.4% in 1985, to 21.3% in 1990, to 16.3% in 1993, and to 11.5% in 1997. The decrease in the prevalence of anti-hepatitis A virus was more marked in young adults who had never travelled in endemic countries (decrease of 20%) than those who had visited or lived in developing countries (decrease of 10%).

CONCLUSION

Although France is not highly endemic for hepatitis A thanks to improved hygiene and housing conditions over the past 20 years, a pattern of intermediate endemicity was seen in French overseas areas in which the risk of outbreaks of hepatitis A was higher. The decrease in anti-hepatitis A virus seroprevalence in French youth can be used to draft a public health policy for hepatitis A control.

Role of cytochrome P-4502C9 in irbesartan oxidation by human liver microsomes

The oxidative metabolism of irbesartan, a new nonpeptide angiotensin II receptor antagonist, was investigated on 12 human fully characterized hepatic microsomes and purified cytochrome P-450 (CYP) isoforms. After incubation of microsomes with irbesartan and NADPH, four main hydroxy metabolites were formed, as confirmed by liquid chromatography-mass spectrometry analysis. Irbesartan oxidation follows Michaelis-Menten kinetics, consistent with the involvement of a single CYP isoform in these hydroxylation processes. Only a low interindividual variability (2-fold difference) was observed in drug oxidation, even in preparations lacking CYP2D6. Km and Vmax for irbesartan oxidation were 54 +/- 6.5 microM and 0.62 +/- 0.18 nmol/min/mg, respectively. Irbesartan oxidation correlated (r2 = 0. 769) with tolbutamide (CYP2C9 substrate) 4-methyl-hydroxylation. Oxidation of irbesartan was markedly inhibited by sulfaphenazole (CYP2C9 inhibitor), but not by any of several other CYP inhibitors. In the same manner, both tolbutamide and warfarin (CYP2C9 substrates), were competitive-type inhibitors of irbesartan oxidation with Ki values of 500 and 30 microM, respectively. Moreover, irbesartan was a competitive-type inhibitor of tolbutamide 4-methylhydroxylation (Ki = 317 microM). Nifedipine also potentially decreased irbesartan oxidation, whereas neither ketoconazole and triacetyloleandomycin (CYP3A inhibitors), nor diltiazem and verapamil, (CYP3A4 substrates), exhibited an inhibitory effect. Additional studies demonstrated that nifedipine was an inhibitor of irbesartan (Ki = 20 microM) and tolbutamide oxidation processes, whereas irbesartan had no effect at all on nifedipine dehydrogenation. Enzyme kinetics suggest that nifedipine is a noncompetitive-type inhibitor of CYP2C9-mediated catalytic activities. Finally, only microsomes containing recombinant human liver CYP2C9 were capable of oxidizing irbesartan. These results provide evidence that CYP2C9 plays a major role in irbesartan oxidation.

Correlation between oral drug absorption in humans, and apparent drug permeability in TC-7 cells, a human epithelial intestinal cell line: comparison with the parental Caco-2 cell line

PURPOSE

To determine and compare the relationship between in vivo oral absorption in humans and the apparent permeability coefficients (Papp) obtained in vitro on two human intestinal epithelial cell lines, the parental Caco-2 and the TC-7 clone.

METHODS

Both cell lines were grown for 5-35 days on tissue culture-treated inserts. Cell monolayers were analysed for their morphology by transmission electron micrography, and for their integrity with respect to transepithelial electrical resistance, mannitol and PEG-4000 transport, and cyclosporin efflux. Papp were determined for 20 compounds exhibiting large differences in chemical structure, molecular weight, transport mechanisms, and percentage of absorption in humans.

RESULTS

The TC-7 clone exhibits morphological characteristics similar to those of the parental Caco-2 cell line, concerning apical brush border, microvilli, tight junctions and polarisation of the cell line. The TC-7 clone however appeared more homogenous in terms of cell size. Both cell lines achieved a similar monolayer integrity towards mannitol and PEG-4000. Monolayer integrity was achieved earlier for the TC-7 clone, mainly due to its shorter doubling time, i.e. 26 versus 30 hours for parental Caco-2 cells. When using cyclosporin A as a P-glycoprotein substrate, active efflux was lower in the TC-7 clone than in the parental Caco-2 cells. The Papp and mechanisms of transport (paracellular or transcellular routes, passive diffusion and active transport) were determined for 20 drugs. A relationship was established between the in vivo oral absorption in humans and Papp values, allowing to determine a threshold value for Papp of 2 10(-6) cm/sec, above for which a 100% oral absorption could be expected in humans. Both correlation curves obtained with the two cell types, were almost completely superimposable. These studies also confirmed that the dipeptide transporter is underexpressed in both cell lines.

CONCLUSIONS

On the basis of morphological parameters, biochemical activity and drug transport characteristics, the TC-7 clone appeared to be a valuable alternative to the use of parental Caco-2 cells for drug absorption studies.

[Consequences for labile blood products of leukocyte depletion by whole blood filtration using the Leucoflex LST1 in-line filter. Evaluation of the Leucoflex LST1 filter]

The aim of this study is to evaluate the effects of whole blood filtration after a storage time of 20-24 hours at laboratory temperature using the in line filter Leucoflex LST1. The study concerns 49 blood donations in which we studied leukocyte depletion, proteins (IgG, IgA, IgM, haptoglobin, C3, C4), coagulation factors (fibrinogen, factors XII, XI, IX, VIII, V, proteins S and C, plasminogen, tPA, D-Dimers, PDF) at day 1, the parameters of conservation (ATP, 2-3 DPG, extra cellular potassium, haemolysis, pH) of red blood cell concentrates (RCCs) and bacteriological sterility at day 1 and 42. Despite a correct leukocyte depletion (mean depletion of 3.96 log), a 10 fold higher mean level of residual leukocytes/unit than with buffy coat poor RCC filtration (0.514.10(6) vs 0.051.10(6)) is observed. Moreover a lot of concentrates are not in accordance with French regulations (7/42 with more than 1.10(6) leukocytes/unit). The variation of the rates of IgG, IgA, IgM, haptoglobin, C4 and protein C is not significant. For the others there is a slight decrease with a mean level remaining in a physiological range. No sign of activation is noted. The sterility assays remain negative and the RCC conservation is not altered. In conclusion, even if the quality of the leukocyte depletion is not satisfactory in our study and has to be stated more precisely by multicenter studies, the whole blood filtration does not alter the quality of the derived components and allows us obtain RCC in a bigger volume and containing more haemoglobin than with the classical procedure after removing the buffy-coat [10].

Cytochrome P450 isoform inhibitors as a tool for the investigation of metabolic reactions catalyzed by human liver microsomes

Cytochrome P450 chemical inhibitors are widely used to define the role of individual cytochrome P450 isozyme(s) in a metabolism process. In this study, cytochrome P450 isoform-dependent reactions were investigated on our human liver microsomes bank (n = 34) and characterized for both KM and VMAX values (n > or = 3). These metabolic reactions were: 7-ethoxyresorufin O-deethylation (CYP1A1), phenacetin O-deethylation (CYP1A2), coumarin 7-hydroxylation (CYP2A6), tolbutamide 4-methylhydroxylation (CYP2C9), dextromethorphan O-demethylation (CYP2D6), aniline 4-hydroxylation (CYP2E1) and nifedipine dehydrogenation (CYP3A4). Literature data-based specific inhibitors were selected and characterized for both their inhibitory constant (Ki) and the inhibition-type toward their specific substrate. Results were as follows: alpha-naphthoflavone (CYP1A1; mixed-type interaction with a Ki = 0.01 microM), furafylline (CYP1A2; competitive-type interaction with a Ki = 3 microM when microsomes were incubated with both furafylline and phenacetin; noncompetitive-type interaction with a Ki = 0.6 microM when microsomes were preincubated with furafylline and NADPH), pilocarpine (CYP2A6; competitive-type interaction with a Ki = 4 microM), sulfaphenazole (CYP2C9; competitive-type interaction with a Ki = 0.3 microM), quinidine (CYP2D6; competitive-type interaction with a Ki = 0.4 microM, diallyldisulfide (CYP2E1; noncompetitive-type interaction with a Ki = 150 microM on an aniline concentration range of 10-60 microM; competitive-type interaction with a Ki = 100 microM on an aniline concentration range of 80-2000 microM) and ketoconazole (CYP3A4; mixed-type interaction with a Ki = 0.015 microM). Once the inhibitors' potency was determined, the selective effects of these inhibitors were evaluated after incubation of human hepatic microsomes with isoform-selective substrates in the presence of the different chemical inhibitors. Up to 10 times the Ki value toward the isoform-selective probe, pilocarpine, sulfaphenazole, quinidine and ketoconazole exhibited potent inhibitory and specific effects. alpha-Naphthoflavone and furafylline both inhibited phenacetin and 7-ethoxyresorufin O-deethylation processes, a consequence of the absence of CYP1A1 in noninduced human liver. Diallyldisulfide exhibited broad and nonspecific inhibitory effects. When used in their "window of selectivity," ie., up to 10-fold the Ki value, most chemical inhibitors powerfully and specifically inhibited cytochrome P450 isoform-specific reactions when analyzed at their KM values.

Fourier-transform lidar

We propose a new method based on the differential absorption lidar technique for multipollutant detection. A broadband laser is sent into the atmosphere in a wavelength range in which several pollutants absorb. The backscattered light is analyzed by a Fourier-transform spectrometer with time resolution. This mode of detection provides both spatial and high spectral resolution down to 0.01 cm(-1), allowing range-resolved measurements of several pollutants simultaneously. To demonstrate the feasibility of this method, we have measured water vapor concentration by using more than 10 individual lines in the 720-nm absorption band. The potential and the limitations are discussed critically.

The human intestinal epithelial cell line Caco-2; pharmacological and pharmacokinetic applications

The gastrointestinal tract remains the most popular and acceptable route of administration for drugs. It offers the great advantage of convenience and many compounds are well absorbed and thereby provide acceptable plasma concentration-time profiles. Currently there is considerable interest from the pharmaceutical industry in development of cell culture systems that would mimic the intestinal mucosa in order to evaluate strategies for investigating and/or enhancing drug absorption. The intestinal epithelial cells of primary interest, from the standpoint of drug absorption and metabolism, are the villus cells, which are fully differentiated cells. An in vitro cell culture system consisting of a monolayer of viable, polarized and fully differentiated villus cells, similar to that found in the small intestine, would be a valuable tool in the study of drug and nutrient transport and metabolism. The Caco-2 cell line, which exhibits a well-differentiated brush border on the apical surface and tight junctions, and expresses typical small-intestinal microvillus hydrolases and nutrient transporters, has proven to be the most popular in vitro model (a) to rapidly assess the cellular permeability of potential drug candidates, (b) to elucidate pathways of drug transport (e.g., passive versus carrier mediated), (c) to assess formulation strategies designed to enhance membrane permeability, (d) to determine the optimal physicochemical characteristics for passive diffusion of drugs, and (e) to assess potential toxic effects of drug candidates or formulation components on this biological barrier. Since differentiated Caco-2 cells express various cytochrome P450 isoforms and phase II enzymes such as UDP-glucuronosyltransferases, sulfotransferases and glutathione-S-transferases, this model could also allow the study of presystemic drug metabolism.

Risk factors for hepatitis A infection in France: drinking tap water may be of importance

The prevalence of serologic markers for hepatitis A was investigated in 936 French male military recruits from October 1992 to June 1993. Data were collected in order to assess the evolution of seroprevalence level according to the decline observed for several years and to appreciate the importance of potential risk factors. The overall prevalence of antibody against hepatitis A virus was 16.3%. The prevalence was higher among those with high number of siblings and whose Father's occupation falls into low professional class categories. Multivariate analysis found that high level of seroprevalence was also associated with tap water consumption (odd ratio (OR) = 1.56; p < 0.04), overseas travels (OR = 2.26; p < 0.001) and was higher for recruits reporting an history of clinical jaundice (OR = 2.27; p < 0.01). Together with more anticipated factors, tap water consumption may be of importance in France and this study points out the potential part taken by chlorinated water.

In vitro N-glucuronidation of SB 47436 (BMS 186295), a new AT1 nonpeptide angiotensin II receptor antagonist, by rat, monkey and human hepatic microsomal fractions

The glucuronidation of the AT1 nonpeptide angiotensin II receptor antagonist, SR 47436 (BMS 186295), was investigated in hepatic microsomes prepared from various species, i.e., Sprague-Dawley rat, Cynomolgus monkey and Caucasian humans. The drug was found to undergo N-glucuronidation on the tetrazole moiety as confirmed by its hydrolysis by beta-glucuronidase, its associated radioactivity when UDP-[U-14C]glucuronic acid was used as substrate and by different techniques such as high-performance liquid chromatography-mass spectrometry and nuclear magnetic resonance. Glucuronide formation was optimal at pH 5.0 along with a "0.2 mg of Brij 58 per mg of protein" ratio, regardless of the investigated species. Cynomolgus monkey microsomes glucuronidated SR 47436 (BMS 186295) to the greatest extent, with a relative catalytic efficiency 11.0- and 2.6-fold higher than that observed in rat and human, respectively. SR 47436 (BMS 186295) glucuronidation followed Michaelis-Menten kinetics. Bilirubin:UDP-glucuronosyltransferase isoform was not involved, inasmuch as bilirubin did not affect its glucuronidation, 7,7,7-triphenylheptanoic acid was a noncompetitive inhibitor and glucuronidation was only decreased 2-fold in Gunn rats. SR 47436 (BMS 186295) glucuronidation was enhanced markedly after treatment of rats with dexamethasone (Vmax/Km = 71.5 vs. 2.6 in untreated animals). Among the drugs used which undergo phenolic, carboxylic acid, alcohol or tertiary amine glucuronidation, only monodigitoxigenin-monodigitoxoside, flurbiprofen, naproxen, testosterone and estrone inhibited SR 47436 (BMS 186295) glucoronidation in a noncompetitive manner. These data suggest that SR 47436 (BMS 186295) was glucuronidated by a highly dexamethasone-inducible UDP-glucuronosyltransferase isoform(s), different from that involved in the glucuronidation of monodigitoxigenin-monodigitoxoside.