A bioinspired approach for the modulation of electroosmotic flow and protein-surface interactions in capillary electrophoresis using silylated amino-amides blocks and covalent grafting

We explore a bioinspired approach to design tailored functionalized capillary electrophoresis (CE) surfaces based on covalent grafting for biomolecules analysis. First, the approach aims to overcome well-known common obstacles in CE protein analysis affecting considerably the CE performance (asymmetry, resolution, and repeatability) such as the unspecific adsorption on fused silica surface and the lack of control of electroosmotic flow (EOF). Then, our approach, which relies on new amino-amide mimic hybrid precursors synthesized by silylation of amino-amides (Si-AA) derivatives with 3-isocyanatopropyltriethoxysilane, aims to recapitulate the diversity of protein-protein interactions (π-π stacking, ionic, Van der Waals…) found in physiological condition (bioinspired approach) to improve the performance of CE protein analysis (electrochromatography). As a proof of concept, these silylated Si-AA (tyrosinamide silylation, serinamide silylation, argininamide silylation, leucinamide silylation, and isoglutamine silylation acid) have been covalently grafted in physiological conditions in different amount on bare fused silica capillary giving rise to a biomimetic coating and allowing both the modulation of EOF and protein-surface interactions. The analytical performances of amino-amide functionalized capillaries were assessed using lysozyme, cytochrome C and ribonuclease A and compared to traditional capillary coatings poly(ethylene oxide), poly(diallyldimethylammonium chloride), and sodium poly(styrenesulfonate). EOF, protein adsorption rate, protein retention factor k, and selectivity were determined for each coating. All results obtained showed this approach allowed to modulate the EOF, reduce unspecific adsorption, and generate specific interactions with proteins by varying the nature and the amount of Si-AA in the functionalization mixture.

Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy

OBJECTIVE

Dentin, enamel and the transition zone, called the dentin-enamel junction (DEJ), have an organization and properties that play a critical role in tooth resilience and in stopping the propagation of cracks. Understanding their chemical and micro-biomechanical properties is then of foremost importance. The aim of this study is to apply Brillouin microscopy on a complex biological structure, that is, the DEJ, and to compare these results with those obtained with Raman microscopy.

DESIGN

Both techniques allow noncontact measurements at the microscopic scale. Brillouin microscopy is based on the interaction between acoustic phonons and laser photons and gives a relation between the frequency shift of the scattered light and the stiffness of the sample. Raman spectra contain peaks related to specific chemical bonds.

RESULTS

Comparison of the Brillouin and Raman cartographies reveals correlations between mechanical and chemical properties. Indeed, the shapes of the phosphate content and stiffness curves are similar. The two spectroscopies give compatible values for the mean distance between two tubules, i.e., 4-6 µm. Moreover, for the first time, the daily cross striations of enamel could be studied, indicating a relationship between the variation in the phosphate concentration and the variation in the rigidity within the enamel prisms.

CONCLUSIONS

We demonstrate here the possibility of using Brillouin scattering microscopy to both study complex biological materials such as the enamel-dentin junction and visualize secondary structures. Correlations between the chemical composition and mechanical properties could help in better understanding the tissue histology.

The Rise of the OM-LoC: Opto-Microfluidic Enabled Lab-on-Chip

The integration of optical circuits with microfluidic lab-on-chip (LoC) devices has resulted in a new era of potential in terms of both sample manipulation and detection at the micro-scale. On-chip optical components increase both control and analytical capabilities while reducing reliance on expensive laboratory photonic equipment that has limited microfluidic development. Notably, in-situ LoC devices for bio-chemical applications such as diagnostics and environmental monitoring could provide great value as low-cost, portable and highly sensitive systems. Multiple challenges remain however due to the complexity involved with combining photonics with micro-fabricated systems. Here, we aim to highlight the progress that optical on-chip systems have made in recent years regarding the main LoC applications: (1) sample manipulation and (2) detection. At the same time, we aim to address the constraints that limit industrial scaling of this technology. Through evaluating various fabrication methods, material choices and novel approaches of optic and fluidic integration, we aim to illustrate how optic-enabled LoC approaches are providing new possibilities for both sample analysis and manipulation.

Shear Wave Elastography, A New Tool for Diaphragmatic Qualitative Assessment. A Translational Study

RATIONALE

Prolonged mechanical ventilation (MV) is often associated either with a decrease (known atrophy) or an increase (supposed injury) in diaphragmatic thickness. Shear wave elastography is a non-invasive technique that measures shear modulus, a surrogate of tissue stiffness and mechanical properties.

OBJECTIVES

To describe changes in shear modulus (SM) during the ICU stay and the relationship with alterations in muscle thickness. To perform a comprehensive ultrasound-based characterization of histological and force production changes occurring in the diaphragm.

METHODS

Translational study using critically ill patients and mechanically ventilated piglets. Serial ultrasound examination of the diaphragm collecting thickness and SM was performed in both patients and piglets. Transdiaphragmatic pressure and diaphragmatic biopsies were collected in piglets.

MEASUREMENTS AND MAIN RESULTS

We enrolled 102 patients, 88 of whom were invasively mechanically ventilated. At baseline, SM was 14.3+/-4.3 kPa and diaphragm end-expiratory thickness was 2.0+/-0.5 mm. Decrease or increase by more than 10% from baseline was reported in 86% of the patients for thickness and in 92% of the patients for shear modulus. An increase in diaphragmatic thickness during the stay was associated with a decrease in SM (β=-9.34±4.41; p=0.03) after multivariable analysis. In the piglet sample, a decrease in SM over 3 days of MV was associated with loss of force production, slow and fast fiber atrophy and increased lipid droplets accumulation.

CONCLUSIONS

Increases in diaphragm thickness during critical illness is associated with decreased tissue stiffness as demonstrated by shear wave ultrasound elastography, consistent with the development of muscle injury and weakness.

Fractal Structure in Silica and Composites Aerogels

Silica aerogels are known to be materials with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption, and low-thermal conductivity. In addition, these unique properties are mainly related to their specific processing. Depending on the aerogel synthesis procedure, the aerogels texture can be tailored with meso and/or macroporosity. Fractal geometry has been observed and used to describe silica aerogels at nanoscales in certain conditions. In this review paper, we describe the fractal structure of silica aerogels that can develop depending on the synthesis conditions. X-ray and neutron scattering measurements allow to show that silica aerogels can exhibit a fractal structure over one or even more than two orders of magnitude in length. The fractal dimension does not depend directly on the material density but can vary with the synthesis conditions. It ranges typically between 1.6 and 2.4. The effect of the introduction of silica particles or of further thermal treatment or compression of the silica aerogels on their microstructure and their fractal characteristics is also resumed.

A Citrus Based Sensory Functional Food Ingredient Induces Antidepressant-like Effects: Possible Involvement of an Interplay between the Olfactory and the Serotonergic Systems

In the present study, we examined the neurobehavioral effects of a sensory functional food ingredient mainly based on Citrus sinensis extracts (D11399) using a battery of tests recapitulating various endophenotypes of depression such as anxiety in the open field (OF), the elevated plus-maze (EPM), and the novelty suppressed feeding (NSF), self-care in the splash test (ST), despair in the forced swimming task (FST) but also anhedonia in the sucrose preference test (SPT) in mice. A one-week oral administration of D11399 promoted anxiolytic- and antidepressant-like responses in naïve mice subjected to the NSF and FST. In a marked contrast, the administration of D11399 by oral gavage or the inhibition of olfaction by methimazole prevented such beneficial effects. We further investigated the neurobehavioral properties of a ten-week oral administration of D11399 in the corticosterone (CORT) mouse model of depression. Interestingly, D11399 also elicited anxiolytic- and antidepressant-like effects in various paradigms. To characterize the putative underpinning neurobiological mechanisms in CORT mice, we investigated whether cellular and molecular processes commonly associated with antidepressant responses such as monoaminergic neurotransmission and neuronal maturation in the hippocampus were impacted. Although D11399 did not modify the hippocampal extracellular levels of monoamines (i.e. serotonin and norepinephrine), it reversed the ability of CORT to decrease serotonin neurons firing rate in the dorsal raphe and neuronal maturation in the hippocampus. These findings suggest that the anxiolytic- and antidepressant-like effects of this sensory functional food ingredient are closely related with olfaction and likely a concomitant change in the activity of the central serotonergic system. Further experiments are warranted to precise the neuronal circuits linking sensorial and emotional modalities and identify innovative therapeutic strategies aimed to relieve depressive endophenotypes.

Real-time shear wave ultrasound elastography: a new tool for the evaluation of diaphragm and limb muscle stiffness in critically ill patients

BACKGROUND

Muscle weakness following critical illness is the consequence of loss of muscle mass and alteration of muscle quality. It is associated with long-term disability. Ultrasonography is a reliable tool to quantify muscle mass, but studies that evaluate muscle quality at the critically ill bedside are lacking. Shear wave ultrasound elastography (SWE) provides spatial representation of soft tissue stiffness and measures of muscle quality. The reliability and reproducibility of SWE in critically ill patients has never been evaluated.

METHODS

Two operators tested in healthy controls and in critically ill patients the intra- and inter-operator reliability of the SWE using transversal and longitudinal views of the diaphragm and limb muscles. Reliability was calculated using the intra-class correlation coefficient and a bootstrap sampling method assessed their consistency.

RESULTS

We collected 560 images. Longitudinal views of the diaphragm (ICC 0.83 [0.50-0.94]), the biceps brachii (ICC 0.88 [0.67-0.96]) and the rectus femoris (ICC 0.76 [0.34-0.91]) were the most reliable views in a training set of healthy controls. Intra-class correlation coefficient for inter-operator reproducibility and intra-operator reliability was above 0.9 for all muscles in a validation set of healthy controls. In critically ill patients, inter-operator reproducibility and intra-operator 1 and 2 reliability ICCs were respectively 0.92 [0.71-0.98], 0.93 [0.82-0.98] and 0.92 [0.81-0.98] for the diaphragm; 0.96 [0.86-0.99], 0.98 [0.94-0.99] and 0.99 [0.96-1] for the biceps brachii and 0.91 [0.51-0.98], 0.97 [0.93-0.99] and 0.99 [0.97-1] for the rectus femoris. The probability to reach intra-class correlation coefficient greater than 0.8 in a 10,000 bootstrap sampling for inter-operator reproducibility was respectively 81%, 84% and 78% for the diaphragm, the biceps brachii and the rectus femoris respectively.

CONCLUSIONS

SWE is a reliable technique to evaluate limb muscles and the diaphragm in both healthy controls and in critically ill patients.

TRIAL REGISTRATION

The study was registered (ClinicalTrial NCT03550222).

Microfluidic Systems for Droplet Generation in Aqueous Continuous Phases: A Focus Review

Microfluidics is one of the most fascinating fields that researchers have been trying to apply in a large number of scientific disciplines over the past two decades. Among them, the discipline of food and pharmaceutical formulation encountered several obstacles when combining microfluidics with aqueous media. Indeed, the physical properties of liquids at micrometric volumes being particular, the droplet generation within microfluidic devices is a big challenge to be met. This focus review is intended to be an initiation for those who would like to generate microdroplets in microfluidic systems involving aqueous continuous phases. It provides a state-of-the-art look at such systems while focusing on the microfluidic devices used, their applications to form a wide variety of emulsions and particles, and the key role held by the interface between the device channels and the emulsion. This review also leads to reflections on new materials that can be used in microfluidic systems with aqueous continuous phases.

Hybrid Organic-Inorganic photoresists, a promising class of materials for Optofluidic integration

Through the efforts to fuse planar optics and microfluidics in order to produce dye lasers, biosensors, trapping and cell sorting device, we can notice the rising interest in optofluidics since early and mid 2000's. However mass production of these devices heavily relies on fast and easy patterning of the constituent material. PDMS, being one of these materials, gained an added value because of its elasticity, hydrophobicity and permeability to gaz. Nonetheless, these specifications are not convenient for all types of applications. The growing capability to use Hybrid Organic-Inorganic materials for the fabrication of integrated optics components and microfluidic channels is what makes this class of materials an ideal candidate for this integration. This work aims to implement, on the same chip, an optical and a microfluidic layer using Sol-Gel processing of Organic-Inorganic materials. The interest in this vertical integration arises from the need to manipulate the fluid in the microchannels using evanescent field optical pressure.

Pharmacokinetic and antimicrobial activity of a new carvacrol-based product against a human pathogen, Campylobacter jejuni

AIM

In vitro and in vivo studies were conducted to test a new carvacrol-based product designed to delay the carvacrol release so that it could reach the caeca of broiler chickens in order to control Campylobacter jejuni.

METHODS AND RESULTS

Antimicrobial activity of carvacrol, a constituent of oregano and thyme essential oil, has been demonstrated against C. jejuni in vitro, and this compound was found beneficial for broiler growth. Here, we tested a new liquid formulation that did not change the antibacterial efficacy of carvacrol against C. jejuni in vitro, as assessed by broth microdilution. The mode of action of carvacrol also remained unchanged as illustrated by electronic microscopy. A pharmacokinetic assay monitored carvacrol of the solid galenic formulation in the avian digestive tract and this showed that this compound was mainly found in the last part (caeca, large intestine) and in the droppings. Extremely low concentrations of free carvacrol were present in blood plasma, with larger amounts of carvacrol metabolites: carvacrol glucuronide and sulphate. A qPCR analysis showed that the solid galenic form of carvacrol added at 5 kg per tonne of food (i.e. 9·5 mg of carvacrol per kg of bodyweight per day) significantly decreased the C. jejuni caecal load by 1·5 log.

CONCLUSIONS

The new liquid formulation was as effective as unformulated carvacrol in vitro. In vivo the solid galenic form seems to delay the carvacrol release into the caeca and presented interesting results on C. jejuni load after 35 days.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results suggested that this product could be promising to control Campylobacter contamination of broilers.

Late toxicities and clinical outcome at 5 years of the ACCORD 12/0405-PRODIGE 02 trial comparing two neoadjuvant chemoradiotherapy regimens for intermediate-risk rectal cancer

Background

Outcome of intermediate risk rectal cancer may be improved by the addition of oxaliplatin during 5-fluoruracil concomitant neoadjuvant chemoradiotherapy. The purpose of this study is to analyze the main clinical results of the ACCORD12 trial (NCT00227747) in rectal cancer after 5 years of follow-up.

Patients and methods

Inclusion criteria were as follows: rectal adenocarcinoma accessible to digital examination staged T3-T4 Nx M0 (or T2 Nx distal anterior rectum). Two neoadjuvant chemoradiotherapy regimens were randomized: CAP45 (RT 45 Gy + capecitabine) and CAPOX50 (RT 50 Gy + capecitabine and oxaliplatin). Main end point was sterilization of the operative specimen. Acute and late toxicities were prospectively analyzed with dedicated questionnaires.

Results

Between November 2005 and July 2008, 598 patients were included in the trial. After a median follow-up of 60.2 months, there was no difference between treatment arms in multivariate analysis either for disease-free survival or overall survival (OS) [P = 0.9, hazard ratio (HR)=1.02; 95% confidence interval (CI), 0.76-1.36 and P = 0.3, HR = 0.87; 95% CI, 0.66-1.15, respectively]. There was also no difference of local control in univariate analysis (P = 0.7, HR = 0.92; 95% CI, 0.51-1.66). Late toxicities were acceptable with 1.6% G3 anal incontinence, and <1% G3 diarrhea, G3 rectal bleeding, G3 stenosis, G3-4 pain, G3 urinary incontinence, G3 urinary retention and G3 skeletal toxicity. There was a slight increase of erectile dysfunction over time with a 63% rate of erectile dysfunction at 5 years. There was no significant statistical difference for these toxicities between treatment arms.

Conclusions

The CAPOX50 regimen did not improve local control, disease-free survival and overall survival in the ACCORD12 trial. Late toxicities did not differ between treatment arms.

Chemical & Nano-mechanical Study of Artificial Human Enamel Subsurface Lesions

White lesions represent an early phase of caries formation. 20 human sound premolars were subjected to pH cycling procedure to induce subsurface lesions (SLs) in vitro. In addition, 2 teeth with naturally developed white spot lesions (WSLs) were used as references. All specimens characterized by confocal Raman microscopy being used for the first time in examining white & subsurface lesions and providing a high resolution chemical and morphological map based on phosphate peak intensity alterations at 960 cm-1. Nanoindentation technique was used to measure Hardness (H) and Young's modulus (E) of enamel. Phosphate map of examined samples exhibited presence of intact surface layer (ISL) followed by severe depletion in (PO43-) peak in the area corresponding to the body of the lesion. In all examined groups, the mechanical properties of enamel were decreased in lesion area and found to be inversely related to penetration depth of indenter owing to enamel hierarchical structure. By combining the above two techniques, we linked mechanical properties of enamel to its chemical composition and ensured that the two methods are highly sensitive to detect small changes in enamel composition. Further work is required to bring these two excellent tools to clinical application to perceive carious lesions at an early stage of development.

Vegetable oil hybrid films cross-linked at the air-water interface: formation kinetics and physical characterization

Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating-free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated using nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored, and finally cytotoxicity tests were performed on fibroblasts proving the absence of film toxicity. The results of this work pave the way to a straightforward synthesis of castor-oil films with tunable mechanical properties: hybrid films cross-linked at the air-water interface combine an easy and cheap spreading protocol with the features of their thermal history optimized for possible future micro/nano drug loading, thus representing excellent candidates for the replacement of non-environmentally friendly petroleum-based materials.

Synthesis and characterization of a photosensitive organic–inorganic, hybrid positive resin type material: application to the manufacture of microfluidic devices by laser writing

A chemically amplified photosensitive organic–inorganic hybrid material based on PAA polymer, TVEB as a crosslinking dissolution inhibitor, a VEPTES pre-hydrolysed as an organic–inorganic material and a PAG photoacid generator was developed.

New organic–inorganic hybrid material based on a poly(amic acid) oligomer: a promising opportunity to obtain microfluidic devices by a photolithographic process

Miniaturized total analysis systems are becoming a powerful tool for analytical and bioanalytical applications.

Proteomic analysis of residual proteins in blades and petioles of fallen leaves of Brassica napus

Brassica napus L. is an important crop plant, characterised by high nitrogen (N) levels in fallen leaves, leading to a significant restitution of this element to the soil, with important consequences at the economic and environmental levels. It is now well established that the N in fallen leaves is due to weak N remobilisation that is especially related to incomplete degradation of foliar proteins during leaf senescence. Identification of residual proteins in a fallen leaf (i.e. incompletely degraded in the last step of the N remobilisation process) constitutes important information for improving nutrient use efficiency. Proteome analysis of the vascular system (petioles) and blades from fallen leaves of Brassica napus was performed, and the 30 most abundant residual proteins in each tissue were identified. Among them, several proteins involved in N recycling remain in the leaf after abscission. Moreover, this study reveals that some residual proteins are associated with energy metabolism, protection against oxidative stress, and more surprisingly, photosynthesis. Finally, comparison of blade and petiole proteomes show that, despite their different physiological roles in the non-senescing leaf, both organs redirect their metabolism in order to ensure catabolic reactions. Taken together, the results suggest that a better degradation of these leaf proteins during the senescence process could enable improvements in the N use efficiency of Brassica napus.

Rhinoceros feet step out of a rule-of-thumb: a wildlife imaging pioneering approach of synchronized computed tomography-digital radiography

Currently, radiography is the only imaging technique used to diagnose bone pathology in wild animals situated under “field conditions”. Nevertheless, while chronic foot disease in captive mega-herbivores is widely reported, foot radiographic imaging is confronted with scarcity of studies. Numerous hindrances lead to such limited numbers and it became very clear that the traditional perspective on bone imaging in domestic animals based on extensive studies and elaborated statistical evaluations cannot be extrapolated to their non-domestic relatives. For these reasons, the authors initiated a multi-modality imaging study and established a pioneering approach of synchronized computed tomography (CT) and digital radiography (DR), based on X-ray projections derived from three-dimensional CT reconstructed images. Whereas this approach can be applied in any clinical field, as a case of outstanding importance and great concern for zoological institutions, we selected foot bone pathologies in captive rhinoceroses to demonstrate the manifold applications of the method. Several advances were achieved, endowing the wildlife clinician with all-important tools: prototype DR exposure protocols and a modus operandi for foot positioning, advancing both traditional projections and, for the first-time, species-related radiographic views; assessment of radiographic diagnostic value for the whole foot and, in premiere, for each autopodial bone; together with additional insights into radiographic appearance of bone anatomy and pathology with a unique, simultaneous CT-DR correlation. Based on its main advantages in availing a wide range of keystone data in wildlife imaging from a limited number of examined subjects and combining advantages of CT as the golden standard method for bone diseases' diagnostic with DR's clinical feasibility under field conditions, synchronized CT-DR presents a new perspective on wildlife's health management. With this we hope to provide veterinary clinicians with concrete imaging techniques and substantial diagnostic tools, which facilitate straightforward attainment and interpretation of field radiography images taken worldwide.

One small step for rhinos, one giant leap for wildlife management--imaging diagnosis of bone pathology in distal limb

Chronic foot disease poses a threat to the general health, represents a tremendous clinical challenge, and often is a reason for euthanasia in captive megaherbivores, among them the elephant and rhinoceros. Nevertheless, apart from the elephant, foot pathology is handled as being confined only to soft tissues whereas bone pathology is often overlooked. As a case in point, the authors selected the second largest mammal on land, the rhinoceros. We performed a computed tomographic (CT) study using the highest resolution available in veterinary world, followed by digital radiography of eight distal limbs from two white and one Indian rhinoceroses. Our study demonstrated that bone pathology in rhinoceroses’ foot is present and in large numbers, yet none of these were diagnosed ante mortem. Even when the animals were euthanized due to foot problems, the decision was based on soft tissue pathology rather than orthopedic reasons. Even more worrying is the fact that the largest number of osteopathologies was present in one of the white rhinoceroses that showed no discernable related clinical signs. This study describes for the first time the existence of bone pathology in white rhinoceros foot, in addition to the two previously described rhinoceros species - Indian and black rhinoceroses. Furthermore, the chronic foot disease reported for the Indian rhinoceros in our study was not restricted to soft tissue structures as was presumed ante mortem but included severe bone pathology. New evidence suggesting that osteopathology in rhinoceroses’ distal limb is more widespread than it was thought before could force us to rethink of radiographic diagnosis in captive megaherbivores as routine examination incorporated into their health management. The anticipated improvements in radiologic examinations in megaherbivores will increase the effectiveness of their management and husbandry and open the way for improved animal welfare and better wildlife conservation.

Do initial S reserves and mineral S availability alter leaf S-N mobilization and leaf senescence in oilseed rape?

Winter oilseed rape is sensitive to S limitation, however few studies have clearly assessed the impact of initial S reserves on the remobilization of leaf N-S compounds and senescence dynamics within the leaves in S limited plants. As a consequence, the impacts of high or low initial S reserves on these parameters, further cross-combined with either high or low S availabilities, were examined using a ¹⁵N and ³⁴S double-labelling method associated with a study of gene expression of relevant tonoplastic sulphate transporters (BnSultr4;1 and BnSultr4;2) and a molecular indicator of leaf senescence (BnSAG12/BnCab). Plants with high initial S status and S limitation showed an optimal growth comparable to control plants. Moreover, in response to S limitation, leaf soluble protein content, total S, recently assimilated S (i.e., ³⁴S) and the sulphate content in the oldest leaves declined, and the expression of genes encoding tonoplastic sulphate transporters were up-regulated. However, compared to control plants, S limitation delayed leaf senescence. These data suggested that in response to S limitation, plants with high initial S were able to sustain optimized leaf growth by increasing endogenous N and S remobilization independently of the leaf senescence process. In contrast, if these low S plants had no initial S reserves, leaf N-S remobilization was not sufficient to allow optimal growth. As a conclusion, our study supports a model where oilseed rape is able to compensate transiently for S limitation through a fine management of leaf N-S remobilization and a delayed leaf senescence dynamics.

Is the remobilization of S and N reserves for seed filling of winter oilseed rape modulated by sulphate restrictions occurring at different growth stages?

How the remobilization of S and N reserves can meet the needs of seeds of oilseed rape subject to limitation of S fertilization remains largely unclear. Thus, this survey aims to determine the incidence of sulphate restriction [low S (LS)] applied at bolting [growth stage (GS) 32], visible bud (GS 53), and start of pod filling (GS 70) on source-sink relationships for S and N, and on the dynamics of endogenous/exogenous S and N contributing to seed yield and quality. Sulphate restrictions applied at GS 32, GS 53, and GS 70 were annotated LS(32), LS(53), and LS(70). Long-term (34)SO(4)(2-) and (15)NO(3)(-) labelling was used to explore S and N partitioning at the whole-plant level. In LS(53), the sulphur remobilization efficiency (SRE) to seeds increased, but not enough to maintain seed quality. In LS(32), an early S remobilization from leaves provided S for root, stem, and pod growth, but the subsequent demand for seed development was not met adequately and the N utilization efficiency (NUtE) was reduced when compared with high S (HS). The highest SRE (65 ± 1.2% of the remobilized S) associated with an efficient foliar S mobilization (with minimal residual S concentrations of 0.1-0.2% dry matter) was observed under LS(70) treatment, which did not affect yield components.

Effect of mineral sulphur availability on nitrogen and sulphur uptake and remobilization during the vegetative growth of Brassica napus L

Because it has a high demand for sulphur (S), oilseed rape is particularly sensitive to S limitation. However, the physiological effects of S limitation remain unclear, especially during the rosette stage. For this reason a study was conducted to determine the effects of mineral S limitation on nitrogen (N) and S uptake and remobilization during vegetative growth of oilseed rape at both the whole-plant and leaf rank level for plants grown during 35 d with 300 microM (34)SO(4)(2-) (control plants; +S) or with 15 microM (34)SO(4)(2-) (S-limited plants; -S). The results highlight that S-limited plants showed no significant differences either in whole-plant and leaf biomass or in N uptake, when compared with control plants. However, total S and (34)S (i.e. deriving from S uptake) contents were greatly reduced for the whole plant and leaf after 35 d, and a greater redistribution of endogenous S from leaves to the benefit of roots was observed. The relative expression of tonoplast and plasmalemma sulphate transporters was also strongly induced in the roots. In conclusion, although S-limited plants had 20 times less mineral S than control plants, their development remained surprisingly unchanged. During S limitation, oilseed rape is able to recycle endogenous S compounds (mostly sulphate) from leaves to roots. However, this physiological adaptation may be effective only over a short time scale (i.e. vegetative growth).

Remobilization of leaf S compounds and senescence in response to restricted sulphate supply during the vegetative stage of oilseed rape are affected by mineral N availability

The impact of sulphur limitation on the remobilization of endogenous S compounds during the rosette stage of oilseed rape, and the interactions with N availability on these processes, were examined using a long-term (34)SO(4)(2-) labelling method combined with a study of leaf senescence progression (using SAG12/Cab as a molecular indicator) and gene expression of the transporters, BnSultr4;1 and BnSultr4;2, involved in vacuolar sulphate efflux. After 51 d on hydroponic culture at 0.3 mM (34)SO(4)(2-) (1 atom% excess), the labelling was stopped and plants were subject for 28 d to High S-High N (HS-HN, control), Low S-High N (LS-HN) or Low S-Low N (LS-LN) conditions. Compared with the control, LS-HN plants showed delayed leaf senescence and, whilst the shoot growth and the foliar soluble protein amounts were not affected, S, (34)S, and SO(4)(2-) amounts in the old leaves declined rapidly and were associated with the up-regulation of BnSultr4;1. In LS-LN plants, shoot growth was reduced, leaf senescence was accelerated, and the rapid S mobilization in old leaves was accompanied by decreased (34)S and SO(4)(2-), higher protein mobilization, and up-regulation of BnSultr4;2, but without any change of expression of BnSultr4;1. The data suggest that to sustain the S demand for growth under S restriction (i) vacuolar SO(4)(2-) is specifically remobilized in LS-HN conditions without any acceleration of leaf senescence, (ii) SO(4)(2-) mobilization is related to an up-regulation of BnSultr4;1 and/or BnSultr4;2 expression, and (iii) the relationship between sulphate mobilization and up-regulation of expression of BnSultr4 genes is specifically dependent on the N availability.

Randomized multicenter phase III trial comparing two neoadjuvant chemoradiotherapy (CT-RT) regimens (RT45-Cap versus RT50-Capox) in patients (pts) with locally advanced rectal cancer (LARC): Results of the ACCORD 12/0405 PRODIGE 2

LBA4007

Background: Following the results of randomized trials FFCD 9203 and EORTC 2291, neoadjuvant CT-RT is considered standard treatment for LARC. The ACCORD 12/0405 PRODIGE 2 trial was initiated to optimize this regimen. Methods: Pts with T3 or resectable T4 N0–1-2 M0, rectal adenocarcinoma were randomized to arm A: concurrent RT 45Gy/25f/5 weeks (w) + capecitabine (800mg/m2/bid) or arm B: concurrent RT 50Gy/25f/5w + capecitabine (800mg/m2/bid/5/7days) + oxaliplatine 50mg/m2/w. Resection with Total Mesorectum Excision was scheduled 6 weeks after the end of CT-RT. Adjuvant chemotherapy was optional. 590 patients were needed to show an increase in the pathological complete response (Dworak) rate from 11% (arm A) to 20% (arm B). Circumferential positive rectal margin (CRM R1) was defined as the presence of residual cancer cells within 0 to 1 mm from the perirectal surface. Results: This trial closed in 07/2008 after randomization of 598 pts since 11/2005. Patients characteristics of 586 eligible pts were well balanced: male 66%, median age 61 years, 66% low rectum, 87% T3 stage. Data base was locked in March 2009. Results are reported in Table . Conclusions: The RT 50 capox regimen is compatible with surgery in 98% of cases with no increase in postoperative complication. In the RT 50 arm, there is a trend in favour of a higher rate of pathological complete sterilization and lower rate of positive CRM. These data could contribute to design a new standard preoperative regimen for LARC. 50 Gy/25 F/5 weeks combined with concurrent chemotherapy could be proposed as an efficient schedule.

[Table: see text]

No significant financial relationships to disclose.

Randomized multicenter phase III trial comparing two neoadjuvant chemoradiotherapy (CT-RT) regimens (RT45-Cap versus RT50-Capox) in patients (pts) with locally advanced rectal cancer (LARC): Results of the ACCORD 12/0405 PRODIGE 2

LBA4007

The full, final text of this abstract will be available in Part II of the 2009 ASCO Annual Meeting Proceedings, distributed onsite at the Meeting on May 30, 2009, and as a supplement to the June 20, 2009, issue of the Journal of Clinical Oncology.

No significant financial relationships to disclose.

Cryptogein affects expression of alpha3, alpha6 and beta1 20S proteasome subunits encoding genes in tobacco

Twelve alpha and beta 20S proteasome subunits cDNAs showing 70-82% identity with the corresponding genes in Arabidopsis or rice, and features of eukaryotic proteasome subunits were cloned in tobacco. Only beta1-tcI 7, alpha3 and alpha6, 20S proteasome subunits encoding genes were up-regulated by cryptogein, a proteinaceous elicitor of plant defence reactions. These results led to the hypothesis that the activation of beta1-tcI 7, alpha3 and alpha6 could induce a specific proteolysis involved in the hypersensitive response and systemic acquired resistance monitored by cryptogein.

Hydrogen peroxide induces programmed cell death features in cultured tobacco BY-2 cells, in a dose-dependent manner

Active oxygen species (AOS), especially hydrogen peroxide, play a critical role in the defence of plants against invading pathogens and in the hypersensitive response (HR). This is characterized by the induction of a massive production of AOS and the rapid appearance of necrotic lesions is considered as a programmed cell death (PCD) process during which a limited number of cells die at the site of infection. This work was aimed at investigating the mode of cell death observed in cultures of BY-2 tobacco cells exposed to H(2)O(2). It was shown that H(2)O(2) is able to induce various morphological cell death features in cultured tobacco BY-2 cells. The hallmarks of cell death observed with fluorescent and electron microscopy differed greatly with the amount of H(2)O(2) added to the cell culture. The appearance of nuclear fragmentation similar to 'apoptotic bodies' associated with a fragmentation of the nuclear DNA into small fragments appear for almost 18% of the cells treated with 12.5 mM H(2)O(2). The early stages of the induction of this PCD process consisted in cell shrinkage and chromatin condensation at the periphery of the nucleus. Above 50 mM, H(2)O(2) induces high necrotic cell death. These data suggest that H(2)O(2)-induced cell damage is associated with the induction of various cell death processes that could be involved differently in plant defence reactions.