Dual Contributions of Analyte Adsorption and Electroosmotic Inhomogeneity to Separation Efficiency in Capillary Electrophoresis of Proteins.

Improving separation efficiency in capillary electrophoresis (CE) requires systematic study of the influence of the electric field (or solute linear velocity) on plate height for a better understanding of the critical parameters controlling peak broadening. Even for poly(diallyldimethylammonium chloride) (PDADMAC)/poly(sodium styrenesulfonate) (PSS) successive multiple ionic-polymer layer (SMIL) coatings, which lead to efficient and reproducible separations of proteins, plate height increases with migration velocity, limiting the use of high electric fields in CE. Solute adsorption onto the capillary wall was generally considered as the main source of peak dispersion, explaining this plate height increase. However, experiments done with Taylor dispersion analysis and CE in the same conditions indicate that other phenomena may come into play. Protein adsorption with slow kinetics and few adsorption sites was established as a source of peak broadening for specific proteins. Surface charge inhomogeneity was also identified as a contribution to plate height due to local electroosmotic fluctuations. A model was proposed and applied to partial PDADMAC/poly(ethylene oxide) capillary coatings as well as PDADMAC/PSS SMIL coatings. Atomic force microscopy with topography and recognition imaging enabled the determination of roughness and charge distribution of the PDADMAC/PSS SMIL surface.

Potato Production in Northwestern Europe (Germany, France, the Netherlands, United Kingdom, Belgium): Characteristics, Issues, Challenges and Opportunities.

In Northwestern Europe, Germany, France, the Netherlands, the UK and Belgium constitute the biggest five potato producers, with total potato crop production around 60% of EU-28 production before Brexit. Soil and climate conditions are highly favourable for potato growth in this region. Production is under driving forces of (i) the potato processing industry, particularly in Belgium; (ii) the innovation for fresh potato in the UK, France and Germany; (iii) the leadership of Germany and the Netherlands for starch potato; and (iv) the dominance of the Netherlands for seed production. Based on an industrial agri-food production system, the region has the highest potato yield levels worldwide and developed relevant trade networks for export of seed, fresh and processed potato products in and outside Europe. Conventional and intensive potato production is widespread over the region, whilst organic production started to develop in Germany and France. Whether the coming decades will be as successful as the last ones for sustainable potato production will depend on how the sector and stakeholders of the whole potato value-chain will overcome new issues and challenges. These are mainly soil quality and health conservation, consequences of climate change, increasing bans on the use of plant protection products, tightening environmental standards, food waste reduction and increasing trade tensions hampering the flow of potatoes around the world. After a detailed description of the potato production in the region, this paper contains a SWOT analysis aiming to identify potential solutions to overcome environmental, technical, economic, political and societal issues in the region for sustainable potato production in the coming years and decades.

Quantification of Adsorption and Optimization of Separation of Proteins in Capillary Electrophoresis.

The improvement of separation efficiency for protein analysis in capillary electrophoresis (CE) is a challenging topic in which protein adsorption onto the capillary wall plays a crucial role. In this work, a simple method allowing the quantification of the adsorption of proteins onto the coated or untreated inner surface of the fused silica capillary was developed based on the determination of the retention factor by measuring separation efficiency of individual proteins at different separation voltages (i.e., different linear velocities). This approach was applied to the quantification of the residual adsorption of four test proteins on five-layer polyelectrolyte coatings and bare fused silica capillary. It allows to get a fair ranking of the coating performances toward protein adsorption, whatever their apparent electrophoretic mobilities (migration times) are. Due to the existence of (even low) residual adsorption, the electrophoretic operating conditions (electric field, capillary length, and internal diameter) can be optimized to improve the separation performances resulting in experimental separation efficiency up to ∼600 000 plates.m-1 in conditions compatible with MS coupling. This approach represents a crucial step in the course to get antifouling coatings for protein separation in CE. It can be used for the evaluation and ranking of virtually any coating (neutral or charged) in CE.

Acoustophoretic Mobility and Its Role in Optimizing Acoustofluidic Separations.

In the separation sciences, sample species are separated according to their physicochemical properties, the nature of the selective field, and, if present, the properties of the medium in which they are dissolved or suspended. Separations may be carried out on a continuous basis in microfluidic devices or split-flow thin channel (SPLITT) devices by selectively transporting species in a direction transverse to the direction of flow of the suspending fluid. Separation is achieved in the so-called transport mode according to relative differences in mobility of the species under the influence of the applied field. Gravitational, centrifugal, thermal gradient, magnetic, electric, and dielectric fields may all be used for continuous SPLITT fractionation. We present here the theory for optimizing the operation of the relatively new technique of acoustic SPLITT fractionation for the continuous separation of non-Brownian materials. The theory is based on a quantitatively defined acoustophoretic mobility that is consistent with the generalized concept of mobility proposed by Giddings. Until now, acoustophoretic mobility has almost exclusively been used as a qualitative descriptor for velocity induced by an acoustic field. The quantitative definition presented here will contribute to the advancement of all forms of acoustofluidic separations.

Limits in Size of Taylor Dispersion Analysis: Representation of the Different Hydrodynamic Regimes and Application to the Size-Characterization of Cubosomes.

Taylor dispersion analysis (TDA) is an absolute method (no calibration needed) for the determination of the molecular diffusion coefficient (D) based on the band broadening of a solute in a laminar flow. TDA is virtually applicable to any solute with size ranging from angstrom to sub-micrometer. The higher sizing limit is restricted by the occurrence of possibly two regimes: convective and hydrodynamic chromatography (HDC) regimes, which have different physical origins that should not be confused. This work aims at clearly defining the experimental conditions for which these two regimes can play a role, alone or concomitantly. It also calculates the relative error on D due to the HDC regime according to the solute to capillary size ratio. It is demonstrated in this work that HDC does not significantly affect the TDA measurement as long as the hydrodynamic radius of the solute is lower than 0.0051 times the capillary radius. Experimental illustrations of the occurrence of the two regimes are given taking polystyrene nanoparticles as model solutes. Finally, application of TDA to the sizing of large real-life solutes is proposed, taking cubosomes as new drug nanocarriers of potential interest for drug delivery purposes.

Quantitative analysis in capillary electrophoresis: transformation of raw electropherograms into continuous distributions.

Quantitative analysis in capillary electrophoresis based on time-scale electropherograms generally uses time-corrected peak areas to account for the differences in apparent velocities between solutes. However, it could be convenient and much more relevant to change the time-scale electropherograms into mass relative distribution of the effective mobility or any other characteristic parameter (molar mass, chemical composition, charge density, ...). In this study, the theoretical background required to perform the variable change on the electropherogram was developed with an emphasis on the fact that both x and y axes should be changed when the time scale electropherograms are modified to get the distributions. Applications to the characterization of polymers and copolymers by different modes of capillary electrophoresis (CE) are presented, including the molar mass distribution of poly-L-lysine oligomers by capillary gel electrophoresis (CGE), molar mass distribution of end-charged poly-l-alanine by free solution CE, molar mass distribution of evenly charged polyelectrolytes by CGE, and charge density distribution of variously charged polyelectrolytes by free solution CE.

Measuring arbitrary diffusion coefficient distributions of nano-objects by taylor dispersion analysis.

Taylor dispersion analysis is an absolute and straightforward characterization method that allows determining the diffusion coefficient, or equivalently the hydrodynamic radius, from angstroms to submicron size range. In this work, we investigated the use of the Constrained Regularized Linear Inversion approach as a new data processing method to extract the probability density functions of the diffusion coefficient (or hydrodynamic radius) from experimental taylorgrams. This new approach can be applied to arbitrary polydisperse samples and gives access to the whole diffusion coefficient distributions, thereby significantly enhancing the potentiality of Taylor dispersion analysis. The method was successfully applied to both simulated and real experimental data for solutions of moderately polydisperse polymers and their binary and ternary mixtures. Distributions of diffusion coefficients obtained by this method were favorably compared with those derived from size exclusion chromatography. The influence of the noise of the simulated taylorgrams on the data processing is discussed. Finally, we discuss the ability of the method to correctly resolve bimodal distributions as a function of the relative separation between the two constituent species.

Polydispersity analysis of Taylor dispersion data: the cumulant method.

Taylor dispersion analysis is an increasingly popular characterization method that measures the diffusion coefficient, and hence the hydrodynamic radius, of (bio)polymers, nanoparticles, or even small molecules. In this work, we describe an extension to current data analysis schemes that allows size polydispersity to be quantified for an arbitrary sample, thereby significantly enhancing the potentiality of Taylor dispersion analysis. The method is based on a cumulant development similar to that used for the analysis of dynamic light scattering data. Specific challenges posed by the cumulant analysis of Taylor dispersion data are discussed, and practical ways to address them are proposed. We successfully test this new method by analyzing both simulated and experimental data for solutions of moderately polydisperse polymers and polymer mixtures.

Impact of comprehensive geriatric assessment on survival, function, and nutritional status in elderly patients with head and neck cancer: protocol for a multicentre randomised controlled trial (EGeSOR).

BACKGROUND: Survival is poorer in elderly patients with head and neck squamous cell carcinomas [HNSCCs] than in younger patients. Possible explanations include a contribution of co-morbidities to mortality, frequent refusal of standard therapy, and the use of suboptimal treatments due to concern about toxicities. The Comprehensive Geriatric Assessment [CGA] is a multidimensional assessment of general health that can help to customise treatment and follow-up plans. The CGA has been proven effective in several health settings but has not been evaluated in randomised studies of patients with cancer. Our aim here was to assess the impact of the CGA on overall survival, function, and nutritional status of elderly patients with HNSCC. METHODS/DESIGN: EGeSOR is an open-label, multicentre, randomised, controlled, parallel-group trial in patients aged 70 years or older and receiving standard care for HNSCC. The intervention includes four components: the CGA conducted by a geriatrician before cancer treatment, participation of the same geriatrician in cancer treatment selection, a standardised geriatric therapeutic intervention designed by the same geriatrician; and geriatric follow-up for 24 months. The primary endpoint, assessed after 6 months, is a composite criterion including death, functional impairment [Activities of Daily Living score decrease ≥ 2], and weight loss ≥ 10%. Secondary endpoints include progression-free survival, unscheduled admissions, quality of life, treatment toxicities, costs, and completion of the planned cancer treatment. A centralised online system is used to perform 1:1 randomisation with a minimisation algorithm for centre, age, T and N stages, and tumour site [oral, oropharyngeal, hypopharyngeal, or laryngeal]. The estimated sample size is 704 patients, who are being recruited by 14 centres in 9 French cities. DISCUSSION: EGeSOR is the first randomised trial of the CGA in elderly cancer patients. We expect the CGA to have direct clinical benefits on the management of elderly patients with HNSCC. If this expectation is fulfilled, the trial may lead to modifications of the management model for elderly patients with cancer. TRIAL REGISTRATION: Trial registration: NCT02025062.

On the optimization of operating conditions for Taylor dispersion analysis of mixtures.

In this work, we investigate the possibility of optimizing the operating conditions, namely mobilizing pressure, capillary length and capillary radius, for performing Taylor dispersion analysis on solutes having hydrodynamic diameter, 2Rh, between 1 and 100 nm. Optimizing Taylor dispersion analysis means finding the set of operating conditions that verify the conditions of validity of this method, and finding the most appropriate conditions that may enhance or maximize the separation performances. Our conclusion is that the performances of Taylor dispersion analysis are independent of the operating conditions, as far as the conditions of validity of the method are verified. The inequalities defining the set of acceptable operating conditions are given in this work as a function of the maximal relative error on the diffusion coefficient, D, fixed by the user. These inequalities define operating zones that were represented for three typical capillary diameters (25, 50 and 100 µm). Within these zones, all experiments should lead to similar results on D (or Rh) and similar separation performances. It was concluded that assuming a 3% relative error on the determination of D, a 60 cm × 50 µm i.d. capillary can be used by default for performing TDA of analytes in the 1-100 nm diameter range with mobilizing pressure in the 50-100 mbar range.

Retention in continuous two-dimensional thermal field-flow fractionation: comparison of experimental results with theory.

A theoretical and experimental study of continuous two-dimensional thermal field-flow fractionation (2D-ThFFF) is presented. Separation takes place in radial flow between two closely spaced discs, one of which is heated and the other cooled in order to maintain a temperature gradient across the channel. The cooled disc, which serves as the accumulation wall, is rotated relative to the other to create a shear component to the fluid flow. Under the influence of the thermal gradient and flow components, the sample components spiral outwards along different paths to the outer rim of the channel to be collected. The general principle of operation is described and an approximate theoretical model formulated for predicting the outlet position for the path of each sample component. The influence of the principal operational parameters, such as radial and angular flow rates and thermal gradient, on the deflection angle of the sample trajectory is investigated. Fractionation is demonstrated for polystyrene polymer standards in a binary solvent consisting of cyclohexane and ethylbenzene. Experimental results are compared with theoretical predictions.

[Treatment of cervical cancer]. / Arbre décisionnel et thérapeutique des cancers du col de l'utérus.

The treatment of uterine cervical cancer evolved the last past twenty years. The management of early stages cervical cancer is based on surgery +/- after an initial brachytherapy in order to increase loco-regional control. A conservative treatment preserving uterine and ovarian functions is sometimes possible for young patients < 40 years old wishing to conceive. This strategy allows pregnancies with low recurrence rate. Finally, the use of the sentinel lymph node staging should be validated within the next few years. The treatment of locally advanced stages is based on concomitant chemoradiation therapy, which allows obtaining an important complete tumour response rate (90%). Thereafter, the irradiation modalities will depend on the para-aortic lymph nodes status diagnosed by PET-computed tomography +/- staging laparoscopic para-aortic lymphadenectomy. The use of completion surgery may be indicated in case of cervical residual disease and has to be balanced with its specific morbidity. All the decisions are made during a multidisciplinary tumour board.

Defining the role of TORC1/2 in multiple myeloma.

Mammalian target of rapamycin (mTOR) is a downstream serine/threonine kinase of the PI3K/Akt pathway that integrates signals from the tumor microenvironment to regulate multiple cellular processes. Rapamycin and its analogs have not shown significant activity in multiple myeloma (MM), likely because of the lack of inhibition of TORC2. In the present study, we investigated the baseline activity of the PI3K/Akt/mTOR pathway TORC1/2 in MM cell lines with different genetic abnormalities. TORC1/2 knock-down led to significant inhibition of the proliferation of MM cells, even in the presence of BM stromal cells. We also tested INK128, a dual TORC1/2 inhibitor, as a new therapeutic agent against these MM cell lines. We showed that dual TORC1/2 inhibition is much more active than TORC1 inhibition alone (rapamycin), even in the presence of cytokines or stromal cells. In vitro and in vivo studies showed that p-4EBP1 and p-Akt inhibition could be predictive markers of TORC2 inhibition in MM cell lines. Dual TORC1/2 inhibition showed better inhibition of adhesion to BM microenvironmental cells and inhibition of homing in vivo. These studies form the basis for further clinical testing of TORC1/2 inhibitors in MM.

Chronic Prostatitis/Chronic Pain Pelvic Syndrome and Male Infertility.

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is defined as urologic pain or discomfort in the pelvic region, associated with urinary symptoms and/or sexual dysfunction, lasting for at least 3 of the previous 6 months. The rate of symptoms related to prostatitis has a mean prevalence of 8-8.2%. CP/CPPS is most frequent in men younger than 50 years, among whom it is the most common urologic diagnosis. In the last decades, many studies have been published on CP/CPPS and its association with male infertility. The pathophysiologic relation between CP/CPPS and male infertility involves several aspects, which are not well studied yet. A reduction in semen parameters has been demonstrated in patients with CP/CPPS, and several mechanisms have been proposed to represent putative pathophysiological links between CP/CPPS and infertility, including male accessory gland inflammation, metabolic syndrome, inflammatory bowel disease, HPV co-infection and autoimmunity. In light of this evidence, a multidisciplinary approach is advocated for patients with known CP/CPPS, and particular attention is needed for male patients of infertile couples in order to evaluate male accessory glands correctly. In addition, it is advisable that future studies dealing with the treatment of CP/CPPS take into consideration all the different pathophysiological aspects implicated.

Size selectivity in field-flow fractionation: lift mode of retention with near-wall lift force.

A simple theoretical model for the size selectivity, S(d), in the lift mode of retention in field-flow fractionation (FFF) is developed on the basis of the near-wall lift force expression. S(d) is made up of two contributions: the flow contribution, S(d,f), arising from the variation of the flow velocity at center of particle due to a change in particle position with particle size, and a slip contribution, S(d,s), arising from the concomitant change in the extent of retardation due to the presence of a nearby channel wall. The slip contribution is minor, but not negligible, and amounts to 10-20% of the overall size selectivity. It contributes to reduce S(d) in sedimentation FFF but to enhance it in flow FFF. S(d) would steadily increase with particle size if the flow profile was linear (Couette flow). Because of the curvature of the flow profile encountered in the classical Poiseuille flow, S(d) exhibits a maximum at some specific particle size. The model predicts a significant difference in S(d) between sedimentation FFF and flow FFF, arising from the different functional dependences of the field force with particle size between these two methods. The predictions are in good agreement with the various S(d) values reported in the literature in both sedimentation and flow FFF. On the basis of the model, guidelines are given for adjusting the operating parameters (carrier flow rate and field strength) to optimize the size selectivity. Finally, it is found that S(d) generally decreases with decreasing channel thickness.

Determination of individual diffusion coefficients in evolving binary mixtures by taylor dispersion analysis: application to the monitoring of polymer reaction.

This study demonstrates that it is possible to get valuable information on the individual populations of a binary mixture from the signal obtained by Taylor dispersion analysis (TDA). In the case of mixtures composed of two populations of different sizes (such as a monomer/polymer mixture), the information available from TDA is not restricted to an average diffusion coefficient or an average hydrodynamic radius calculated on the entire binary mixture. In this work, TDA was used to monitor a polymerization reaction. In this scope, it has been possible to determine the degree of conversion and the weight average hydrodynamic radius of the polymer at different reaction times. Three different methods are proposed for the data processing of taylorgrams derived from polymerization mixtures or, more generally, for taylorgrams of binary mixtures. These three methods, either based on deconvolution or on integration of the signal, were found to give similar results. TDA results obtained for a model binary mixture of acrylamide and standard polyacrylamide were consistent with DLS experiments provided that the differences in the type of average hydrodynamic radius values between the two methods are taken into account. An example of application to the monitoring of acrylamide radical polymerization is shown.

Influence of viscous friction heating on the efficiency of columns operated under very high pressures.

When columns packed with very fine particles are operated at high mobile phase velocities, the friction of the mobile phase percolating through the column bed generates heat. This heat dissipates along and across the column and axial and radial temperature gradients appear. The wall region of the column tends to be cooler than its center, and due to the influence of temperature on the mobile phase viscosity and on the equilibrium constant of analytes, the band velocity is not constant across the column. This radial heterogeneity of the temperature distribution across the column contributes to band broadening. This phenomenon was investigated assuming a cylindrically symmetrical column and using the general dispersion theory of Aris, which relates the height equivalent to the theoretical plate (HETP) contribution due to a radial heterogeneity of the column to the radial distribution of the linear velocities of a compound peak and to the radial distribution of its apparent dispersion coefficients in the column bed. The former is known from the temperature gradient across the column, the temperature dependencies of the mobile phase viscosity, and the retention factor of the compound. The latter is derived from the known expression of the transverse reduced HETP equation for the column. The values of the HETP calculated with the Aris model and a classical HETP equation were compared to those measured on a 2.1 x 50 mm Acquity BEH-C(18) column, run at flow rates of 0.6, 0.95, 1.30, and 1.65 mL/min, with pure acetonitrile as the mobile phase and naphtho[2,3-a]pyrene as the retained compound. These two sets of data are in generally good agreement, although the experimental values of the HETP tend to increase faster with increasing mobile phase velocity than the calculated values.

Randomized clinical trial of post-operative radiotherapy versus concomitant carboplatin and radiotherapy for head and neck cancers with lymph node involvement.

BACKGROUND AND PURPOSE: Post-operative radiotherapy is indicated for the treatment of head and neck cancers. In vitro, chemotherapy potentiates the cytotoxic effects of radiation. We report the results of a randomized trial testing post-operative radiotherapy alone versus concomitant carboplatin and radiotherapy for head and neck cancers with lymph node involvement. MATERIALS AND METHODS: The study involved patients undergoing curative-intent surgery for head and neck cancers with histological evidence of lymph node involvement. Patients were randomly assigned to receive radiotherapy alone (54-72Gy, 30-40 fractions, 6-8 weeks) or identical treatment plus concomitant Carboplatin (50mg/m(2) administered by IV infusion twice weekly). RESULTS: Between February 1994 and June 2002, 144 patients were included. With a median follow-up of 106 months (95% confidence interval (CI) [92-119]), the 2-year rate of loco-regional control was 73% (95% CI: 0.61-0.84) in the combined treatment group and 68% (95% CI: 0.57-0.80) in the radiotherapy group (p=0.26). Overall survival did not differ significantly between groups (hazard ratio for death, 1.05; 95% CI: 0.69-1.60; p=0.81). CONCLUSIONS: Twice-weekly administration of carboplatin concomitant to post-operative radiotherapy did not improve local control or overall survival rates in this population of patients with node-positive head and neck cancers.

Prognostic value of ST-segment resolution after rescue percutaneous coronary intervention. Data from the RICO survey.

OBJECTIVES: The goal of the present study was to test the impact of ST segment resolution (STR) after rescue percutaneous coronary intervention (PCI) on the short-term prognosis. BACKGROUND: The prognostic value of STR after rescue PCI for acute ST elevation myocardial infarction (STEMI) remains undetermined. METHODS: From the French regional database, we analyzed 168 consecutive patients with STEMI and failed lysis, defined by <50 percent STR, who underwent rescue PCI. Patients were classified into two groups according to the degree of STR from the maximal ST-elevation measured on the single worst ECG lead before lysis and after rescue PCI: the without STR group (<50% STR) vs. the with STR group (> or =50%). RESULTS: After rescue PCI, 26 (15%) patients did not have STR and 142 (85%) patients did. No difference was observed between the two groups regarding baseline characteristics, risk factors, and median time delay either from symptom onset to thrombolysis or from failed lysis to rescue PCI. We observed a lower proportion of patients with TIMI 2/3 flow post PCI in the without STR group (respectively 61% vs. 97%, P < 0.001) but an increased use of intra-aortic balloon counterpulsation (34% vs. 8%, P < 0.001) in this group. Thirty-day mortality was markedly higher in the without STR group than in the with STR group (27% vs. 9% respectively, P = 0.025). Moreover, multivariate analysis showed that absence of STR (OR: 5.65; 95% CI: 1.24-25.67), was an independent prognostic factor for mortality. CONCLUSIONS: We showed for the first time that analysis of ST-segment resolution may be a simple reliable tool to identify patients at high risk after rescue PCI, and may provide useful information for the elaboration of therapeutic strategies.

Theoretical and experimental investigation of the focusing position in asymmetrical flow field-flow fractionation (AF4).

To better understand the focusing process and to determine the focusing position (zfoc) in Asymmetrical Flow Field-Flow Fractionation (AF4), theoretical and experimental studies were performed. A new theoretical expression that allows the calculation of zfoc in AF4 channels of any shape having an axial plane of symmetry was established. The equation was then applied to the particular case of a trapezoidal AF4 channel with tapered ends. The applicability of this equation was verified by comparing the calculated results with the experimental measures of the focusing position obtained using blue dextran dye under different flow conditions. The calculated values and the experimental results were in good agreement. The total uncertainty associated with the calculated zfoc was evaluated and was lower than 10%. A good repeatability and reproducibility of the focusing position was obtained. Moreover, the effects of the sample-injection position, the spacer thickness, the membrane aging, and the nature of the injected sample on the focusing position were investigated: zfoc was not influenced by these parameters, proving the universal applicability of the equation given in this work for predicting the focusing position, when the assumption of constancy of the cross-flow velocity at the membrane, which underlies this equation, is fulfilled. Additionally, it is notable that this theoretical expression is suitable for different models of AF4 channel and not peculiar to specific suppliers.