Innovative methodology to transfer conventional GC-MS heroin profiling to UHPLC-MS/MS

Nowadays, in forensic laboratories, heroin profiling is frequently carried out by gas chromatography coupled with mass spectrometry (GC-MS). This analytical technique is well established, provides good sensitivity and reproducibility, and allows the use of large databases. Despite those benefits, recently introduced analytical techniques, such as ultra-high-pressure liquid chromatography (UHPLC), could offer better chromatographic performance, which needs to be considered to increase the analysis throughput for heroin profiling. With the latter, chromatographic conditions were optimized through commercial modeling software and two atmospheric pressure ionization sources were evaluated. Data obtained from UHPLC-MS/MS were thus transferred, thanks to mathematical models to mimic GC-MS data. A calibration and a validation set of representative heroin samples were selected among the database to establish a transfer methodology and assess the models' abilities to transfer using principal component analysis and hierarchical classification analysis. These abilities were evaluated by computing the frequency of successful classification of UHPLC-MS/MS data among GC-MS database. Seven mathematical models were tested to adjust UHPLC-MS/MS data to GC-MS data. A simplified mathematical model was finally selected and offered a frequency of successful transfer equal to 95%. Figur

COMBINATION OF INDEPENDENT COMPONENT ANALYSIS, DESIGN OF EXPERIMENTS AND DESIGN SPACE FOR A NOVEL METHODOLOGY TO DEVELOP CHROMATOGRAPHIC METHODS

As defined by ICH [1] and FDA, Quality by Design (QbD) stands for “a systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management”. A risk–based QbD–compliant approach is proposed for the robust development of analytical methods. This methodology based on Design of Experiments (DoE) to study the experimental domain models the retention times at the beginning, the apex and the end of each peak corresponding to the compounds of a mixture and uses the separation criterion (S) rather than the resolution (RS) as a Critical Quality Attribute. Stepwise multiple linear regressions are used to create the models. The estimated error is propagated from the modelled responses to the separation criterion (S) using Monte Carlo simulations in order to estimate the predictive distribution of the separation criterion (S) over the whole experimental domain. This allows finding ranges of operating conditions that will guarantee a satisfactory quality of the method in its future use. These ranges define the Design Space (DS) of the method. In chromatographic terms, the chromatograms processed at operating conditions within the DS will assuredly show high quality, with well separated peaks and short run time, for instance. This Design Space can thus be defined as the subspace, necessarily encompassed in the experimental domain (i.e. the knowledge space), within which the probability for the criterion to be higher than an advisedly selected threshold is higher than a minimum quality level. Precisely, the DS is defined as “the multidimensional combination and interaction of input variables (e.g., material attributes) and process parameters that have been demonstrated to provide assurance of quality” [1]. Therefore, this DS defines a region of operating conditions that provide prediction of assurance of quality rather than only quality as obtained with traditional mean response surface optimisation strategies. For instance, in the liquid chromatography there is a great difference in e.g. predicting a resolution (RS) higher than 1.5 vs. predicting that the probability for RS to be higher than 1.5 (i.e. P(RS> 1.5)) is high. The presentation of this global methodology will be illustrated for the robust optimisation and DS definition of several liquid chromatographic methods dedicated to the separation of different mixtures: pharmaceutical formulations, API and impurities/degradation products, plant extracts, separation of enantiomers, … References [1] International Conference on Harmonisation (ICH) of Technical Requirements for Registration of Pharmaceuticals for Human Use, Topic Q8(R2): Pharmaceutical development, Geneva, 2009

Incidence of rotavirus gastroenteritis by age in African, Asian and European children: Relevance for timing of rotavirus vaccination

© 2016 The Author(s). Published with license by Taylor & Francis. © GSK Biologicals SA.Variability in rotavirus gastroenteritis (RVGE) epidemiology can influence the optimal vaccination schedule. We evaluated regional trends in the age of RVGE episodes in low- to middle- versus high-income countries in three continents. We undertook a post-hoc analysis based on efficacy trials of a human rotavirus vaccine (HRV; Rotarix™, GSK Vaccines), in which 1348, 1641, and 5250 healthy infants received a placebo in Europe (NCT00140686), Africa (NCT00241644), and Asia (NCT00197210, NCT00329745). Incidence of any/severe RVGE by age at onset was evaluated by active surveillance over the first two years of life. Severity of RVGE episodes was assessed using the Vesikari-scale. The incidence of any RVGE in Africa was higher than in Europe during the first year of life (≤2.78% vs. ≤2.03% per month), but much lower during the second one (≤0.86% versus ≤2.00% per month). The incidence of severe RVGE in Africa was slightly lower than in Europe during the first year of life. Nevertheless, temporal profiles for the incidence of severe RVGE in Africa and Europe during the first (≤1.00% and ≤1.23% per month) and second (≤0.53% and ≤1.13% per month) years of life were similar to those of any RVGE. Any/severe RVGE incidences peaked at younger ages in Africa vs. Europe. In high-income Asian regions, severe RVGE incidence (≤0.31% per month) remained low during the study. The burden of any RVGE was higher earlier in life in children from low- to middle- compared with high-income countries. Differing rotavirus vaccine schedules are likely warranted to maximize protection in different settings

Varicella-zoster virus open reading frame 4 encodes an immediate-early protein with posttranscriptional regulatory properties.

Varicella-zoster virus (VZV) encodes four putative immediate-early proteins based on sequence homology with herpes simplex virus type 1: the products of ORF4, -61, -62, and -63. Until now, only two VZV proteins have been described as being truly expressed with immediate-early kinetics (IE62 and IE63). The ORF4-encoded protein can stimulate gene expression either alone or in synergy with the major regulatory protein IE62. Making use of a sequential combination of transcription and protein synthesis inhibitors (actinomycin D and cycloheximide, respectively), we demonstrated the immediate-early nature of the ORF4 gene product, which can thus be named IE4. The fact that IE4 is expressed with kinetics similar to that of IE62 further underlines the possible cooperation between these two VZV proteins in gene expression. Analysis of the IE4-mediated autologous or heterologous viral gene expression at the mRNA levels clearly indicated that IE4 may have several mechanisms of action. Activation of the two VZV genes tested could occur partly by a posttranscriptional mechanism, since increases in chloramphenicol acetyltransferase (CAT) mRNA levels do not account for the stimulation of CAT activity. On the other hand, stimulation of the human immunodeficiency virus type 1 long terminal repeat- or the cytomegalovirus promoter-associated CAT activity is correlated with an increase in the corresponding CAT mRNA

New Methodology for the Development of Chromatographic Methods

As defined by ICH [1] and FDA, Quality by Design (QbD) stands for “a systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management”. A risk–based QbD–compliant approach is proposed for the robust development of analytical methods. This methodology based on Design of Experiments (DoE) to study the experimental domain models the retention times at the beginning, the apex and the end of each peak corresponding to the compounds of a mixture and uses the separation criterion (S) rather than the resolution (RS) as a Critical Quality Attribute. Stepwise multiple linear regressions are used to create the models. The estimated error is propagated from the modelled responses to the separation criterion (S) using Monte Carlo simulations in order to estimate the predictive distribution of the separation criterion (S) over the whole experimental domain. This allows finding ranges of operating conditions that will guarantee a satisfactory quality of the method in its future use. These ranges define the Design Space (DS) of the method. In chromatographic terms, the chromatograms processed at operating conditions within the DS will assuredly show high quality, with well separated peaks and short run time, for instance. This Design Space can thus be defined as the subspace, necessarily encompassed in the experimental domain (i.e. the knowledge space), within which the probability for the criterion to be higher than an advisedly selected threshold is higher than a minimum quality level. Precisely, the DS is defined as “the multidimensional combination and interaction of input variables (e.g., material attributes) and process parameters that have been demonstrated to provide assurance of quality” [1]. Therefore, this DS defines a region of operating conditions that provide prediction of assurance of quality rather than only quality as obtained with traditional mean response surface optimisation strategies. For instance, in the liquid chromatography there is a great difference in e.g. predicting a resolution (RS) higher than 1.5 vs. predicting that the probability for RS to be higher than 1.5 (i.e. P(RS> 1.5)) is high. The presentation of this global methodology will be illustrated for the robust optimisation and DS definition of several liquid chromatographic methods dedicated to the separation of different mixtures: pharmaceutical formulations, API and impurities/degradation products, plant extracts, separation of enantiomers, … References [1] International Conference on Harmonisation (ICH) of Technical Requirements for Registration of Pharmaceuticals for Human Use, Topic Q8(R2): Pharmaceutical development, Geneva, 2009. Acknowledgements A research grant from the Belgium National Fund for Scientific Research (F.R.S-FNRS) to E. Rozet is gratefully acknowledged

Study of common database feeding with results coming from different analytical methods in the framework of illicit drugs chemical profiling

Analytical results harmonisation is investigated in this study to provide an alternative to the restrictive approach of analytical methods harmonisation which is recommended nowadays for making possible the exchange of information and then for supporting the fight against illicit drugs trafficking. Indeed, the main goal of this study is to demonstrate that a common database can be fed by a range of different analytical methods, whatever the differences in levels of analytical parameters between these latter ones. For this purpose, a methodology making possible the estimation and even the optimisation of results similarity coming from different analytical methods was then developed. In particular, the possibility to introduce chemical profiles obtained with Fast GC-FID in a GC-MS database is studied in this paper. By the use of the methodology, the similarity of results coming from different analytical methods can be objectively assessed and the utility in practice of database sharing by these methods can be evaluated, depending on profiling purposes (evidential vs. operational perspective tool). This methodology can be regarded as a relevant approach for database feeding by different analytical methods and puts in doubt the necessity to analyse all illicit drugs seizures in one single laboratory or to implement analytical methods harmonisation in each participating laboratory

Design Spaces for Analytical Methods

Since the adoption of the ICH Q8 document concerning the development of pharmaceutical processes following a Quality by Design (QbD) approach, there have been many discussions on the opportunity for analytical method developments to follow a similar approach. A key component of the QbD paradigm is the definition of the Design Space of analytical methods where assurance of quality is provided. Several Design Spaces for analytical methods have been published, stressing the importance of this concept. This paper aims at explaining what is an analytical method Design Space, why it is useful for the robust development and optimization of analytical methods and how to build such a Design Space. A strong emphasis is made by distinguishing the usual mean response surface approach, overlapping mean response surfaces and the desirability function one to other probabilistic approaches as only these last ones correctly define a Design Space. In addition, recent publications assessing the Design Space of analytical methods are reviewed and discussed

Study of common database feeding with results coming from different analytical methods in the framework of illicit drugs chemical profiling

Analytical results harmonisation is investigated in this study to provide an alternative to the restrictive approach of analytical methods harmonisation which is recommended nowadays for making possible the exchange of information and then for supporting the fight against illicit drugs trafficking. Indeed, the main goal of this study is to demonstrate that a common database can be fed by a range of different analytical methods, whatever the differences in levels of analytical parameters between these latter ones. For this purpose, a methodology making possible the estimation and even the optimisation of results similarity coming from different analytical methods was then developed. In particular, the possibility to introduce chemical profiles obtained with Fast GC-FID in a GC-MS database is studied in this paper. By the use of the methodology, the similarity of results coming from different analytical methods can be objectively assessed and the utility in practice of database sharing by these methods can be evaluated, depending on profiling purposes (evidential vs. operational perspective tool). This methodology can be regarded as a relevant approach for database feeding by different analytical methods and puts in doubt the necessity to analyse all illicit drugs seizures in one single laboratory or to implement analytical methods harmonisation in each participating laboratory

Third-order nonlinear optical response of Au:SiO

We report a study on the third-order nonlinear optical properties of nanocomposite thin films composed of gold particles embedded in a silica host matrix. Samples of various metal volume fractions, ranging from 8 to 35%, are synthesized by the sputtering technique. Some of them are annealed. Nonlinear optical measurements, which are performed by using the technique, reveal both a very large nonlinear absorption and a weak nonlinear refraction close to the surface plasmon resonance frequency of the particles. We especially study the effect of the metal concentration and the influence of thermal treatment on the real and imaginary components of the third-order nonlinear susceptibility. Our results reveal that, as the metal concentration reaches a few percent, the mutual electromagnetic interactions between particles greatly enlarge the nonlinear optical response of the material and can not be neglected in the theoretical analysis. Moreover, the thermal treatment leads, for a given concentration, to a significant increase of the nonlinear response, which is ascribed to a modification of the material morphology. We finally point out that the material nonlinear properties are very sensitive to the incident wavelength through the local field enhancement phenomenon