Novel miniaturised and highly versatile biomechatronic platforms for the characterisation of melanoma cancer cells

There has been an increasing demand to acquire highly sensitive devices that are able to detect and characterize cancer at a single cell level. Despite the moderate progress in this field, the majority of approaches failed to reach cell characterization with optimal sensitivity and specificity. Accordingly, in this study highly sensitive, miniaturized-biomechatronic platforms have been modeled, designed, optimized, microfabricated, and characterized, which can be used to detect and differentiate various stages of melanoma cancer cells. The melanoma cell has been chosen as a legitimate cancer model, where electrophysiological and analytical expression of cell-membrane potential have been derived, and cellular contractile force has been obtained through a correlation with micromechanical deflections of a miniaturized cantilever beam. The main objectives of this study are in fourfold: (1) to quantify cell-membrane potential, (2) correlate cellular biophysics to respective contractile force of a cell in association with various stages of the melanoma disease, (3) examine the morphology of each stage of melanoma, and (4) arrive at a relation that would interrelate stage of the disease, cellular contractile force, and cellular electrophysiology based on conducted in vitro experimental findings. Various well-characterized melanoma cancer cell lines, with varying degrees of genetic complexities have been utilized. In this study, two-miniaturized-versatile-biomechatronic platforms have been developed to extract the electrophysiology of cells, and cellular mechanics (mechanobiology). The former platform consists of a microfluidic module, and stimulating and recording array of electrodes patterned on a glass substrate, forming multi-electrode arrays (MEAs), whereas the latter system consists of a microcantilever-based biosensor with an embedded Wheatstone bridge, and a microfluidic module. Furthermore, in support of this work main objectives, dedicated microelectronics together with customized software have been attained to functionalize, and empower the two-biomechatronic platforms. The bio-mechatronic system performance has been tested throughout a sufficient number of in vitro experiments.Open Acces

Septin‐based readout of PI(4,5)P2 incorporation into membranes of giant unilamellar vesicles

International audienceSeptins constitute a novel class of cytoskeletal proteins. Budding yeast septins self-assemble into non-polar filaments bound to the inner plasma membrane through specific interactions with L-α-phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). Biomimetic in vitro assays using Giant Unilamellar Vesicles (GUVs) are relevant tools to dissect and reveal insights in proteins-lipids interactions, membrane mechanics and curvature sensitivity. GUVs doped with PI(4,5)P2 are challenging to prepare. This report is dedicated to optimize the incorporation of PI(4,5)P2 lipids into GUVs by probing the proteins-PI(4,5)P2 GUVs interactions. We show that the interaction between budding yeast septins and PI(4,5)P2 is more specific than using usual reporters (phospholipase C1). Septins have thus been chosen as reporters to probe the proper incorporation of PI(4,5)P2 into giant vesicles. We have shown that electro-formation on platinum wires is the most appropriate method to achieve an optimal septin-lipid interaction resulting from an optimal PI(4,5)P2 incorporation for which, we have optimized the growth conditions. Finally, we have shown that PI(4,5)P2 GUVs have to be used within a few hours after their preparation. Indeed, over time, PI(4,5)P2 is expelled from the GUV membrane and the PI(4,5)P2 concentration in the bilayer decreases

Author Correction:Human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Early autoantibody screening for type 1 diabetes: a Kuwaiti perspective on the advantages of multiplexing chemiluminescent assays

Type 1 diabetes (T1D) incidence has increased globally over the last decades, alongside other autoimmune diseases. Early screening of individuals at risk of developing T1D is vital to facilitate appropriate interventions and improve patient outcomes. This is particularly important to avoid life-threatening diabetic ketoacidosis and hospitalization associated with T1D diagnosis. Additionally, considering that new therapies have been developed for T1D, screening the population and individuals at high risk would be of great benefit. However, adopting such screening approaches may not be feasible due to limitations, such as cost, adaptation of such programs, and sample processing. In this perspective, we explore and highlight the use of multiplexing chemiluminescent assays for T1D screening and emphasize on their advantages in detecting multiple autoantibodies simultaneously, maximizing efficiency, and minimizing sample volume requirements. These assays could be extremely valuable for pediatric populations and large-scale screening initiatives, providing a cost-efficient solution with increased diagnostic accuracy and deeper insights into T1D pathogenesis. Eventually, the adoption of such screening methods can help transform T1D diagnosis, especially in countries with high T1D prevalence, such as Kuwait, which will contribute to the development of novel therapeutic interventions, positively impacting the lives of those affected by T1D and other autoimmune diseases

Initial arch wires used in orthodontic treatment with fixed appliances

Background: Initial arch wires are the first arch wires to be inserted into the fixed appliance at the beginning of orthodontic treatment and are used mainly for the alignment of teeth by correcting crowding and rotations. With a number of different types of orthodontic arch wires available for initial tooth alignment, it is important to understand which wire is most efficient, as well as which wires cause least amount of root resorption and pain during the initial aligning stage of treatment. This is an update of the review entitledInitial arch wires for alignment of crooked teeth with fixed orthodontic braces, which was first published in 2010. Objectives: To assess the effects of initial arch wires for the alignment of teeth with fixed orthodontic braces, in terms of the rate of tooth alignment, amount of root resorption accompanying tooth movement, and intensity of pain experienced by patients during the initial alignment stage of treatment. Search methods: Cochrane Oral Health\u27s Information Specialist searched the following databases: Cochrane Oral Health\u27s Trials Register (to 5 October 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 9), MEDLINE Ovid (1946 to 5 October 2017), and Embase Ovid (1980 to 5 October 2017. The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Selection criteria: We included randomised controlled trials (RCTs) of initial arch wires to align teeth with fixed orthodontic braces. We included only studies involving participants with upper or lower, or both, full arch fixed orthodontic appliances. Data collection and analysis: Two review authors were responsible for study selection, \u27Risk of bias\u27 assessment and data extraction. We resolved disagreements by discussion between the review authors. We contacted corresponding authors of included studies to obtain missing information. We assessed the quality of the evidence for each comparison and outcome as high, moderate, low or very low, according to GRADE criteria. Main results: For this update, we found three new RCTs (228 participants), bringing the total to 12 RCTs with 799 participants. We judged three studies to be at high risk of bias, and three to be at low risk of bias; six were unclear. None of the studies reported the adverse outcome of root resorption. The review assessed six comparisons. 1. Multistrand stainless steel versus superelastic nickel-titanium (NiTi) arch wires. There were five studies in this group and it was appropriate to undertake a meta-analysis of two of them. There is insufficient evidence from these studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and superelastic NiTi arch wires (mean difference (MD) -7.5 mm per month, 95% confidence interval (CI) -26.27 to 11.27; 1 study, 48 participants; low-quality evidence). The findings for pain at day 1 as measured on a 100 mm visual analogue scale suggested that there was no meaningful difference between the interventions (MD -2.68 mm, 95% CI -6.75 to 1.38; 2 studies, 127 participants; moderate-quality evidence). 2. Multistrand stainless steel versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from the studies to determine whether there is a difference in rate of alignment between multistrand stainless steel and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured. 3. Conventional NiTi versus superelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is any difference between conventional and superelastic NiTi arch wires with regard to either alignment or pain (low- to very low-quality evidence). 4. Conventional NiTi versus thermoelastic NiTi arch wires. There were two studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment between conventional and thermoelastic NiTi arch wires (low-quality evidence). Pain was not measured. 5. Single-strand superelastic NiTi versus coaxial superelastic NiTi arch wires. There was only one study (24 participants) in this group. There is moderate-quality evidence that coaxial superelastic NiTi can produce greater tooth movement over 12 weeks (MD -6.76 mm, 95% CI -7.98 to -5.55). Pain was not measured. 6. Superelastic NiTi versus thermoelastic NiTi arch wires. There were three studies in this group, but it was not appropriate to undertake a meta-analysis of the data. There is insufficient evidence from these studies to determine whether there is a difference in alignment or pain between superelastic and thermoelastic NiTi arch wires (low-quality evidence). Authors\u27 conclusions: Moderate-quality evidence shows that arch wires of coaxial superelastic nickel-titanium (NiTi) can produce greater tooth movement over 12 weeks than arch wires made of single-strand superelastic NiTi. Moderate-quality evidence also suggests there may be no difference in pain at day 1 between multistrand stainless steel arch wires and superelastic NiTi arch wires. Other than these findings, there is insufficient evidence to determine whether any particular arch wire material is superior to any other in terms of alignment rate, time to alignment, pain and root resorption

Propriétés mécaniques et fonction de CHMP2B dans la voie de remodelage et de scission membranaire par les ESCRT

The ESCRT-III protein complex mediates membrane remodeling in many cellular contexts. The ESCRT pathway has been extensively studied in vivo and partially reconstituted in vitro using yeast proteins. In Homo Sapiens, at least 12 ESCRT-III proteins exist, called Charged Multivesicular Body Protein (CHMP 1-7). Although, the main function of the ESCRT-III protein assemblies is to induce membrane scission by constricting membrane necks, the biophysical mechanism remains unclear and the mechanical properties of the CHMP polymers still poorly characterized. Moreover, the usually accepted sequence of recruitment of the major ESCRT components to the membrane prior to scission is CHMP4-CHMP3-CHMP2A but mammalian cells also have CHMP2B considered to be a CHMP2A isoform; so far, its role remains elusive. We have used biomimetic model systems and purified CHMP proteins to study in vitro protein affinity and effects on membrane by several techniques. We established that CHMP2B binding is enhanced with PI(4,5)P2 lipids, whereas the other human core components have no lipid specificity besides their negative charge. We showed that in the presence of CHMP2B, membranes become rigidified in contrast to CMHP2A as well as CHMP4 and CHMP3, suggesting that CHMP2A and CHMP2B have very distinctive properties. Finally, we show in disagreement with the proposed models, that CHMP4 alone cannot deform membranes. In fact, it requires the interaction with CHMP2B or CHMP2A+3 proteins to do so, forming polymer assemblies that stabilizes tubular membrane structures. These observations provide a novel basis for proposing possible mechanism for membrane constriction in the presence of the ATPase Vps4.Le complexe protéique ESCRT-III conduit au remodelage membranaire dans de nombreux contextes cellulaires. Les ESCRTs ont été largement étudiés in vivo et partiellement reconstitués in vitro sur des protéines de levure. Chez l’Homo Sapiens, il existe au moins 12 protéines ESCRT-III appelées Charged Multivesicular Body Protein (CHMP 1-7). Malgré que la fonction principale de ces assemblages de protéines soit d’induire la scission membrane par constriction du cou des membranes, le mécanisme biophysique reste incertain et les propriétés mécaniques des polymères CHMPs faiblement caractérisées. Par ailleurs, la séquence de recrutement à la membrane généralement considérée pour les composantes principales est CHMP4-CHMP3-CHMP2A. Mais, les cellules mammifères incluent aussi CHMP2B, considérée comme isoforme de CHMP2A et, dont le rôle est méconnu. Nous avons utilisé des systèmes biomimétiques de membranes modèles et des protéines CHMPs purifiées pour étudier in vitro leur affinité et leurs effets sur la membrane par différentes techniques. Nous avons établi que seule CHMP2B a une affinité spécifique aux lipides PI(4,5)P2. Nous montrons qu’en présence de CHMP2B, les membranes deviennent rigides en contraste avec les autres CHMPs et suggérant que CHMP2A et CHMP2B ont des propriétés distinctes. En fin, nous montrons en désaccord avec les modèles proposés, que CHMP4 seule ne peut pas déformer les membranes. Elle requiert l’interaction avec CHMP2B ou CHMP2A+3 pour former des assemblages de polymères qui stabilisent des structures tubulaires de la membrane. Ces observations offrent une nouvelle base pour proposer un mécanisme possible pour la constriction membranaire avec l’ATPase Vps4

Leveling the curve of Spee with round compared with rectangular archwires.

Leveling the curve of Spee with round compared with rectangular archwires

Artifacts in MRI caused by different types of fixed orthodontic appliance - An in vitro study

Aims: The overall aim was to establish the degree of artifacts made by orthodontic appliances in MRI. Specific aim was to investigate if any sequences applied at the investigation could improve the images quality. Materials and Methods: Twelve frequently used orthodontic appliances were tested. The appliances were cemented/bonded on twelve study casts placed in translucent plastic boxes filled with water and contrast. The MRI expositions were performed in a 1.5 Tesla and 3 Tesla scanners respectively (1.5 T: MAGNETOM AvantoFit, 3 T: MAGNETOM Trio, Siemens Healthcare, Erlangen, Germany). The used imaging sequences to reduce the artifacts were 1) turbo spin echo (TSE), 2) TSE combined with view angle tilting (VAT), and 3) TSE with both VAT and slice encoding for metal artifact correction (SEMAC). Results: After the MR imaging and the artifacts reduce imaging sequences technique (TSE, TSE combined with VAT and TSE with VAT and SEMANC) the Orto-pro nickel free brackets showed the largest amount of image artifacts, while the gold chain, titanium brackets and buccal mini-screws showed smallest artifact. TSE with both VAT and SEMAC artifact reduction imaging sequences were the best sequence to improve MRI quality. Conclusion: Titanium brackets showed the smallest artifact compared to conventional and nickel free brackets. TSE with both VAT and SEMAC imaging sequence to reduce the artifacts was superior in improving image quality than the TES and TES combined with VAT

Dynamic and Sequential Protein Reconstitution on Negatively Curved Membranes by Giant Vesicles Fusion

International audienc