Setting clinical performance specifications to develop and evaluate biomarkers for clinical use

Background: Biomarker discovery studies often claim ‘promising’ findings, motivating further studies and marketing as medical tests. Unfortunately, the patient benefits promised are often inadequately explained to guide further evaluation, and few biomarkers have translated to improved patient care. We present a practical guide for setting minimum clinical performance specifications to strengthen clinical performance study design and interpretation. Methods: We developed a step-by-step approach using test evaluation and decision-analytic frameworks and present with illustrative examples. Results: We define clinical performance specifications as a set of criteria that quantify the clinical performance a new test must attain to allow better health outcomes than current practice. We classify the proposed patient benefits of a new test into three broad groups and describe how to set minimum clinical performance at the level where the potential harm of false-positive and false-negative results does not outweigh the benefits. (1) For add-on tests proposed to improve disease outcomes by improving detection, define an acceptable trade-off for false-positive versus true-positive results; (2) for triage tests proposed to reduce unnecessary tests and treatment by ruling out disease, define an acceptable risk of false-negatives as a safety threshold; (3) for replacement tests proposed to provide other benefits, or reduce costs, without compromising accuracy, use existing tests to benchmark minimum accuracy levels. Conclusions: Researchers can follow these guidelines to focus their study objectives and to define statistical hypotheses and sample size requirements. This way, clinical performance studies will allow conclusions about whether test performance is sufficient for intended use

J Musculoskelet Neuronal Interact

Long-term bed-rest is used to simulate the effect of spaceflight on the human body and test different kinds of countermeasures. The 2nd Berlin BedRest Study (BBR2-2) tested the efficacy of whole-body vibration in addition to high-load resisitance exercise in preventing bone loss during bed-rest. Here we present the protocol of the study and discuss its implementation. Twenty-four male subjects underwent 60-days of six-degree head down tilt bed-rest and were randomised to an inactive control group (CTR), a high-load resistive exercise group (RE) or a high-load resistive exercise with whole-body vibration group (RVE). Subsequent to events in the course of the study (e.g. subject withdrawal), 9 subjects participated in the CTR-group, 7 in the RVE-group and 8 (7 beyond bed-rest day-30) in the RE-group. Fluid intake, urine output and axiallary temperature increased during bed-rest (p or = .17). Body weight changes differed between groups (p < .0001) with decreases in the CTR-group, marginal decreases in the RE-group and the RVE-group displaying significant decreases in body-weight beyond bed-rest day-51 only. In light of events and experiences of the current study, recommendations on various aspects of bed-rest methodology are also discussed

Laser decoating of DLC films for tribological applications

Damaged DLC coatings usually require remanufacturing of the entire coated components starting from an industrial chemical de-coating step. Alternatively, a complete or local coating repair can be considered. To pursue this approach, however, a local coating removal is needed as first operation. In this context, controlled decoating based on laser sources can be a suitable and clean alternative to achieve a pre-fixed decoating depth with high accuracy. In the present study, we investigated a laser-based decoating process executed on multilayered DLC films for advanced tribological applications (deposited via a hybrid PVD/PE-CVD technique). The results were acquired via multifocal optical digital microscopy (MF-ODM), which allowed high-resolution 3D surface reconstruction as well as digital profilometry of the lasered and unlasered surface. The study identifies the most critical process parameters which influence the effective decoating depth and the post-decoating surface roughness. In particular, the role of pulse overlap (decomposed along orthogonal directions), laser fluence, number of lasing passes and assist gas is discussed in text. A first experimental campaign was designed to identify the best conditions to obtain full decoating of the DLC + DLC:Cr layers. It was observed that decreasing the marking speed to 200 mm/s was necessary to obtain a sufficient pulse overlap and a nearly planar ablation profile. By operating with microsecond pulses and 1 J/cm2 (fairly above the ablation threshold), less than 10 passes were needed to obtain full decoating of the lasered area with an etching rate of 1.1 μm/loop. Further experiments were then executed in order to minimise the roughness of the rest surface with the best value found at around 0.2 μm. Limited oxidation but higher Ra values were observed in Ar atmosphere

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Les assimilats foliaires du soja et leur utilisation pour le remplissage des graines : influence de l'apport d'azote.

National audienc

Influence du deficit hydrique sur trois varietes de soja : effet sur la proteogenese des graines

National audienceThe drought tolerance of 2 chinese soybean varieties (Glycine max (L.) Merr.) ’Jiangedou’ and ’Quingmoshidou 533’ (’Q.533’), was compared with that of 'Kingsoy’, currently cropped in France. Plots were water-stressed from flowering until pod formation (August 15) and compared with standard plots in maximum evapotranspiration conditions. The effects of this treatment were studied on vegetative growth and fruiting, gaseous exchange, carbon and nitrogen metabolism. During water stress, reduction of gaseous exchange and nitrogen adsorption led to reduced growth and weak fruiting. After 14CO2 incorporation, labelling of nonprotein insoluble compounds was greater in water-stressed than standard leaves, showing less protein synthesis. Ten days after the end of water stress, protein synthesis remained lower by comparison with standard, particularly for ’Q.533’. In fact, this variety’s behaviour was generally very different from that of ’Jiangedou’ and ’Kingsoy’ : vegetative growth increased again to the control level. Water stress decreased carbon and especially nitrogen metabolism and led to a reduction of seed weight at maturity particularly for ’Q.533’. The seed protein level of the three varieties was not modified by the water stress studied.La tolérance au déficit hydrique de 2 variétés de soja (Glycine max (L.) Merr.) d’origine chinoise, « Jiangedou » et « Quingmoshidou 533 » (« Q.533 ») est comparée à celle de la variété « Kingsoy » couramment cultivée en France. Des parcelles dont les plantes sont soumises à une contrainte hydrique sévère depuis le début de la floraison jusqu’à la fin de la formation des gousses (le! juillet-15 août) sont comparées à des parcelles témoins placées dans des conditions d’évapotranspiration maximale. Les répercussions de ce traitement sur le développement végétatif et la fructification, les échanges gazeux et le métabolisme carboné et azoté sont étudiées. Durant la période de déficit hydrique, la réduction des échanges gazeux foliaires et de l’alimentation azotée entraîne une croissance limitée et une fructification déficitaire. Le marquage, après incorporation de 14CO2 des composés insolubles non protéiques est plus important dans les feuilles en déficit hydrique que dans les témoins : ceci témoigne d’une synthèse protéique moins active. Dix jours après avoir supprimé la contrainte hydrique, la synthèse protéique reste plus faible par rapport aux témoins, ceci est particulièrement net pour « Q.533 ». Par ailleurs, le comportement de cette variété, dont le développement végétatif reprend au point d’atteindre celui du témoin, diffère de celui de « Jiangedou » et de « Kingsoy ». Le ralentissement du métabolisme carboné et surtout azoté, provoqué par le déficit hydrique, se traduit, à maturité, par une réduction de la masse des graines récoltées, plus importante pour « Q.533 ». Pour les trois variétés la proportion des protéines dans les graines n’a pas été modifiée par le déficit hydrique étudié