Effectiveness of electronic patient reporting outcomes, by a digital telemonitoring platform, for prostate cancer care: the Protecty study

Research aim and purpose

The benefits of Electronic Patient -Reported Outcomes (e-PRO) for telemonitoring are well established, allowing early detection of illnesses and continuous monitoring of patients. The primary objective of the PROTECTY study was to assess the compliance with patient use of the telemonitoring platform Cureety. An exploratory objective was to assess if the first-month health status is a prognostic factor of progression free-survival (PFS) and overall survival (OS) for prostate cancer patient.

Methods

This prospective study was conducted at the Military Hospital Bégin on prostate cancer patients. Patients were allowed to respond to a symptomatology questionnaire based on CTCAE v.5.0, personalized to their pathology and treatment. An algorithm evaluates the health status of the patient based on the reported adverse events, with a classification into 2 different states: Good Health Status (GHS) and Poor Health status (PHS).

Results

Sixty-one patients were enrolled between July 1st, 2020 and September 30th, 2021. The median age was 74.0 (range 58.0-94.0). 78% presented a metastatic stage, and the most represented cancer was mHSPC. Overall, 2,457 questionnaires were completed by the patients, 4.0% resulted in a health classification in to monitor or critical state. 87% of patients were classified in the GHS group. The compliance was 72% in the overall population during the first month, 71% in GHS group and 75% in PHS group. The median follow-up was 8 months. PFS at 6 months was 84% in GHS group vs. 57% in PHS group, p = 0.19. OS at 6 months was 98% in GHS group vs. 83% in PHS group, p = 0.31.

Conclusions

Our study showed that compliance was satisfactory. The feasibility of remote monitoring for prostate cancer patients means that they should benefit from its implementation. Our study is also the first to assess the correlation between treatment tolerance and survival. The initial results suggest that e-PRO assessment could help identify in the early stages the patients that require further health assessment and potential therapeutic changes. While further follow-up of more patients will be required, our study highlights the importance of e-PRO in cancer patient care.

Microphase separation of living cells

Self-organization of cells is central to a variety of biological systems and physical concepts of condensed matter have proven instrumental in deciphering some of their properties. Here we show that microphase separation, long studied in polymeric materials and other inert systems, has a natural counterpart in living cells. When placed below a millimetric film of liquid nutritive medium, a quasi two-dimensional, high-density population of Dictyostelium discoideum cells spontaneously assembles into compact domains. Their typical size of 100 μm is governed by a balance between competing interactions: an adhesion acting as a short-range attraction and promoting aggregation, and an effective long-range repulsion stemming from aerotaxis in near anoxic condition. Experimental data, a simple model and cell-based simulations all support this scenario. Our findings establish a generic mechanism for self-organization of living cells and highlight oxygen regulation as an emergent organizing principle for biological matter.

Integrated platform for culture, observation, and parallelized electroporation of spheroids

Reversible electroporation is a method to introduce molecules into cells by increasing the permeability of their membranes, thanks to the application of pulsed electric fields. One of its main biomedical applications is electro-chemotherapy, where electroporation is used to deliver anticancer drugs into tumor tissues. To improve our understanding of the electroporation effect on tissues and select efficient treatments, in vitro tumor models are needed. Cell spheroids are relevant models as they can reproduce tumor microenvironment and cell-cell interactions better than 2D cell cultures. Various methods offering a relatively simple workflow are now available for their production. However, electroporation protocols usually require handling steps that may damage spheroids and result in random spacing, inducing variations in electric field distribution around spheroids and non-reproducible electroporation conditions. In addition, only a few microsystems allow the production and electroporation of spheroids, and the spheroids produced lack reproducibility in size and location. To overcome these issues, we developed a unique device enabling culture, monitoring, and electroporation of hundreds of regular spheroids in parallel, with a design ensuring that all spheroids are submitted to the same electric field conditions. It is comprised of a microfluidic chamber encompassing a micro-structured agarose gel, allowing easy medium exchange while avoiding spheroid handling. It also enables optical imaging of spheroids in situ, thanks to transparent electrodes. In this paper, we describe the fabrication and characterization of the developed microsystem and demonstrate its applicability to electroporation of a network of spheroids. We present a first successful application as an anticancer drug testing platform, by evaluating the bleomycin effect on HT29 colorectal cancer cell spheroids. This work opens new perspectives in the development of in vitro assays for the preclinical evaluation of electroporation-based treatment.

Correction: Quantifying nanotherapeutic penetration using a hydrogel-based microsystem as a new 3D in vitro platform

Correction for 'Quantifying nanotherapeutic penetration using a hydrogel-based microsystem as a new 3D in vitro platform' by Saba Goodarzi et al., Lab Chip, 2021, 21, 2495-2510, DOI: 10.1039/D1LC00192B.

Quantifying nanotherapeutic penetration using a hydrogel-based microsystem as a new 3D in vitro platform

The huge gap between 2D in vitro assays used for drug screening and the in vivo 3D physiological environment hampered reliable predictions for the route and accumulation of nanotherapeutics in vivo. For such nanotherapeutics, multi-cellular tumour spheroids (MCTS) are emerging as a good alternative in vitro model. However, the classical approaches to produce MCTS suffer from low yield, slow process, difficulties in MCTS manipulation and compatibility with high-magnification fluorescence optical microscopy. On the other hand, spheroid-on-chip set-ups developed so far require a practical knowledge of microfluidics difficult to transfer to a cell biology laboratory. We present here a simple yet highly flexible 3D model microsystem consisting of agarose-based microwells. Fully compatible with the multi-well plate format conventionally used in cell biology, our simple process enables the formation of hundreds of reproducible spheroids in a single pipetting. Immunostaining and fluorescence imaging including live high-resolution optical microscopy can be performed in situ, with no manipulation of spheroids. As a proof of principle of the relevance of such an in vitro platform for nanotherapeutic evaluation, this study investigates the kinetics and localisation of nanoparticles within colorectal cancer MCTS cells (HCT-116). The nanoparticles chosen are sub-5 nm ultrasmall nanoparticles made of polysiloxane and gadolinium chelates that can be visualized in MRI (AGuIX®, currently implicated in clinical trials as effective radiosensitizers for radiotherapy) and confocal microscopy after addition of Cy5.5. We show that the amount of AGuIX® nanoparticles within cells is largely different in 2D and 3D. Using our flexible agarose-based microsystems, we are able to resolve spatially and temporally the penetration and distribution of AGuIX® nanoparticles within MCTS. The nanoparticles are first found in both extracellular and intracellular space of MCTS. While the extracellular part is washed away after a few days, we evidenced intracellular localisation of AGuIX®, mainly within the lysosomal compartment, but also occasionally within mitochondria. Hence, our agarose-based microsystem appears as a promising 3D in vitro user-friendly platform for investigation of nanotherapeutic transport, ahead of in vivo studies.

A new agarose-based microsystem to investigate cell response to prolonged confinement

Emerging evidence suggests the importance of mechanical stimuli in normal and pathological situations for the control of many critical cellular functions. While the effect of matrix stiffness has been and is still extensively studied, few studies have focused on the role of mechanical stresses. The main limitation of such analyses is the lack of standard in vitro assays enabling extended mechanical stimulation compatible with dynamic biological and biophysical cell characterization. We have developed an agarose-based microsystem, the soft cell confiner, which enables the precise control of confinement for single or mixed cell populations. The rigidity of the confiner matches physiological conditions and its porosity enables passive medium renewal. It is compatible with time-lapse microscopy, in situ immunostaining, and standard molecular analyses, and can be used with both adherent and non-adherent cell lines. Cell proliferation of various cell lines (hematopoietic cells, MCF10A epithelial breast cells and HS27A stromal cells) was followed for several days up to confluence using video-microscopy and further documented by Western blot and immunostaining. Interestingly, even though the nuclear projected area was much larger upon confinement, with many highly deformed nuclei (non-circular shape), cell viability, assessed by live and dead cell staining, was unaffected for up to 8 days in the confiner. However, there was a decrease in cell proliferation upon confinement for all cell lines tested. The soft cell confiner is thus a valuable tool to decipher the effects of long-term confinement and deformation on the biology of cell populations. This tool will be instrumental in deciphering the impact of nuclear and cytoskeletal mechanosensitivity in normal and pathological conditions involving highly confined situations, such as those reported upon aging with fibrosis or during cancer.

Mechanical Control of Cell Proliferation Increases Resistance to Chemotherapeutic Agents

While many cellular mechanisms leading to chemotherapeutic resistance have been identified, there is an increasing realization that tumor-stroma interactions also play an important role. In particular, mechanical alterations are inherent to solid cancer progression and profoundly impact cell physiology. Here, we explore the influence of compressive stress on the efficacy of chemotherapeutics in pancreatic cancer spheroids. We find that increased compressive stress leads to decreased drug efficacy. Theoretical modeling and experiments suggest that mechanical stress decreases cell proliferation which in turn reduces the efficacy of chemotherapeutics that target proliferating cells. Our work highlights a mechanical form of drug resistance and suggests new strategies for therapy.

Constraints on Lorentz Invariance Violation from HAWC Observations of Gamma Rays above 100 TeV

Because of the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The high altitude water Cherenkov (HAWC) observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. HAWC finds evidence of 100 TeV photon emission from at least four astrophysical sources. These observations exclude, for the strongest of the limits set, the LIV energy scale to 2.2×10^{31}  eV, over 1800 times the Planck energy and an improvement of 1 to 2 orders of magnitude over previous limits.

Multiple Galactic Sources with Emission Above 56 TeV Detected by HAWC

We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov Observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.

Collective regulation of cell motility using an accurate density-sensing system

The capacity of living cells to sense their population density and to migrate accordingly is essential for the regulation of many physiological processes. However, the mechanisms used to achieve such functions are poorly known. Here, based on the analysis of multiple trajectories of vegetative Dictyostelium discoideum cells, we investigate such a system extensively. We show that the cells secrete a high-molecular-weight quorum-sensing factor (QSF) in their medium. This extracellular signal induces, in turn, a reduction of the cell movements, in particular, through the downregulation of a mode of motility with high persistence time. This response appears independent of cAMP and involves a G-protein-dependent pathway. Using a mathematical analysis of the cells' response function, we evidence a negative feedback on the QSF secretion, which unveils a powerful generic mechanism for the cells to detect when they exceed a density threshold. Altogether, our results provide a comprehensive and dynamical view of this system enabling cells in a scattered population to adapt their motion to their neighbours without physical contact.

High-Frequency Mechanical Properties of Tumors Measured by Brillouin Light Scattering

The structure of tumors can be recapitulated as an elastic frame formed by the connected cytoskeletons of the cells invaded by interstitial and intracellular fluids. The low-frequency mechanics of this poroelastic system, dictated by the elastic skeleton only, control tumor growth, penetration of therapeutic agents, and invasiveness. The high-frequency mechanical properties containing the additional contribution of the internal fluids have also been posited to participate in tumor progression and drug resistance, but they remain largely unexplored. Here we use Brillouin light scattering to produce label-free images of tumor microtissues based on the high-frequency viscoelastic modulus as a contrast mechanism. In this regime, we demonstrate that the modulus discriminates between tissues with altered tumorigenic properties. Our micrometric maps also reveal that the modulus is heterogeneously altered across the tissue by drug therapy, revealing a lag of efficacy in the core of the tumor. Exploiting high-frequency poromechanics should advance present theories based on viscoelasticity and lead to integrated descriptions of tumor response to drugs.

Publisher Correction: Very-high-energy particle acceleration powered by the jets of the microquasar SS 433

In this Letter, owing to a production error, the penultimate version of the PDF was published. The HTML version was always correct. The PDF has been corrected online.

Drug delivery to tumours using a novel 5-FU derivative encapsulated into lipid nanocapsules

In this work, a novel lipophilic 5-fluorouracil (5-FU) derivative was synthesised and encapsulated into lipid nanocapsules (LNC). 5-FU was modified with lauric acid to give a lipophilic mono-lauroyl-derivative (5-FU-C12, MW of about 342 g/mol, yield of reaction 70%). 5-FU-C12 obtained was efficiently encapsulated into LNC (encapsulation efficiency above 90%) without altering the physico-chemical characteristics of LNC. The encapsulation of 5-FU-C12 led to an increased stability of the drug when in contact with plasma being the drug detectable until 3 h following incubation. Cytotoxicity assay carried out using MTS on 2D cell culture showed that 5-FU-C12-loaded LNC had an enhanced cytotoxic effect on glioma (9L) and human colorectal (HTC-116) cancer cell line in comparison with 5-FU or 5-FU-C12. Then, HCT-116 tumour spheroids were cultivated and the reduction of spheroid volume was measured following treatment with drug-loaded LNC and drugs alone. Similar reduction on spheroids volume was observed following the treatment with drug-loaded LNC, 5-FU-C12 and 5-FU alone, while blank LNC displayed a reduction in cell viability only at high concentration. Globally, our data suggest that the encapsulation increased the activity of the 5-FU-C12. However, in-depth evaluations of LNC permeability into spheroids are needed to disclose the potential of these nanosystems for cancer treatment.

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.

Differences in trochlear parameters between native and prosthetic kinematically or mechanically aligned knees

INTRODUCTION

Kinematic (KA) and mechanical (MA) alignment techniques are two different philosophies of implant positioning that use the same TKA implants. This might generate differences in the resulting prosthetic trochleae parameters between the two techniques of alignment. Our study aim was to test the following hypotheses : (1) mechanically or kinematically aligned femoral implant understuffs the native trochlear articular surface and poorly restores the native groove orientation, and (2) the orientation of the prosthetic trochlear groove and trochlear fill are different between MA and KA.

METHODS

Three-dimensional models of the femur were made from segmentation of preoperative Magnetic Resonance Imaging scans (MRIs) of ten subjects with isolated medial tibiofemoral osteoarthritis. In-house planning and analysis software kinematically and mechanically aligned a modern cruciate retaining femoral component and determined differences in parameters of the trochlear fit between native and prosthetic trochleae, and between KA and MA prosthetic trochleae.

RESULTS

The MA prosthetic trochleae did not fill (understuffed) the entire length of the native medial facet and the proximal 70% of the native groove and lateral facet, and oriented the trochleae groove 8° more valgus than native. The KA prosthetic trochleae understuffed the proximal 70% of the native trochleae, and had a groove 6° more valgus than native. The KA trochleae understuffed the medial facet distally and oriented the groove 2° less valgus and 3° more internally rotated than the MA trochleae.

CONCLUSION

MA and KA prosthetic trochleae substantially understuff and create a prosthetic groove more valgus compared to native trochlear anatomy, and they also differed between each other regarding trochleae stuffing and groove alignment. Although randomized trials have not shown differences in patellofemoral complications between KA and MA, a femoral component designed specifically for KA that more closely restores the native trochlear anatomy might improve patient reported satisfaction and function.

LEVEL OF EVIDENCE

Level 2 controlled laboratory study.

Alignment options for total knee arthroplasty: A systematic review

In spite of improvements in implant designs and surgical precision, functional outcomes of mechanically aligned total knee arthroplasty (MA TKA) have plateaued. This suggests probable technical intrinsic limitations that few alternate more anatomical recently promoted surgical techniques are trying to solve. This review aims at (1) classifying the different options to frontally align TKA implants, (2) at comparing their safety and efficacy with the one from MA TKAs, therefore answering the following questions: does alternative techniques to position TKA improve functional outcomes of TKA (question 1)? Is there any pathoanatomy not suitable for kinematic implantation of a TKA (question 2)? A systematic review of the existing literature utilizing PubMed and Google Scholar search engines was performed in February 2017. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 569 reports, of which 13 met our eligibility criteria. Four alternative techniques to position a TKA are challenging the traditional MA technique: anatomic (AA), adjusted mechanical (aMA), kinematic (KA), and restricted kinematic (rKA) alignment techniques. Regarding osteoarthritic patients with slight to mid constitutional knee frontal deformity, the KA technique enables a faster recovery and generally generates higher functional TKA outcomes than the MA technique. Kinematic alignment for TKA is a new attractive technique for TKA at early to mid-term, but need longer follow-up in order to assess its true value. It is probable that some forms of pathoanatomy might affect longer-term clinical outcomes of KA TKA and make the rKA technique or additional surgical corrections (realignment osteotomy, retinacular ligament reconstruction etc.) relevant for this sub-group of patients. Longer follow-up is needed to define the best indication of each alternative surgical technique for TKA. Level I for question 1 (systematic review of Level I studies), level 4 for question 2.

The kinematic alignment technique for TKA reliably aligns the femoral component with the cylindrical axis

INTRODUCTION

Kinematic alignment (KA) technique is an alternative technique for positioning a TKA, which aims a patient-specific implant positioning in order to reproduce the pre-arthritic knee anatomy. Because reliability in implant positioning is of interest to obtain reproducible good functional results, our study tests the hypothesis that the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically aligned femoral component are similar.

METHODS

Preoperative knee magnetic resonance imaging (MRI) and postoperative knee computed tomography (CT) of 13 patients implanted with a KA Persona^® TKA (Zimmer, Warsaw, USA) using manual instrumentation (kinematically-aligned TKA procedure pack^®, Zimmer Biomet, Warsaw, USA) were segmented to create 3D femoral models. The kinematic alignment position of the femoral component was planned on the 3D model created from the preoperative MRI. Differences in the positions of the planned and surgically implanted kinematically-aligned femoral component were determined with in-house analysis software.

RESULTS

The average differences between the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically-aligned femoral component were inferior to 1mm and no statistically significant. In terms of variability, 62% (8/13) of performed implants matched all four positions within 1.5mm, and the maximum difference was 3mm.

CONCLUSION

In this small series, intraoperative kinematic positioning of the femoral component with the specific manual instrumentation closely matched the planned position, which suggests that this technique reliably aligned the flexion-extension axis of the femoral component to the cylindrical axis.

LEVEL OF EVIDENCE

Level 3.

Mechanical alignment technique for TKA: Are there intrinsic technical limitations?

BACKGROUND

Mechanically aligned (MA) total knee arthroplasty (TKA) is affected by disappointing functional outcomes in spite of the recent improvements in surgical precision and implant designs. This might suggest the existence of intrinsic technical limitations. Our study aims to compare the prosthetic and native trochlear articular surfaces and to estimate the extent of collateral ligament imbalance, which is technically uncorrectable by collateral ligament release when TKA implants are mechanically aligned.

STUDY HYPOTHESIS

Conventional MA technique generates a high rate of prosthetic overstuffing of the distal groove, distal lateral trochlear facet and distal lateral femoral condyle (Hypothesis 1), and technically uncorrectable collateral ligament imbalance (hypothesis 2)? Disregarding the distal femoral joint line obliquity (DFJLO) when performing femoral cuts explains distal lateral femoral prosthetic stuffing and uncorrectable imbalance (hypothesis 3)?

METHODS

Twenty patients underwent a conventional MA TKA. Pre-operative MRI-based 3D knee models were generated and MA TKA was simulated. Native and prosthetic trochlear articular surfaces were compared using in-house analysis software. Following the automatic determination by the planning software of the size of the extension and flexion gaps, an algorithm was applied to balance the gaps and the frequency and amplitude of technically uncorrectable knee imbalance were estimated.

RESULTS

The conventional MA technique generates a significant slight distal lateral femoral prosthetic overstuffing (mean 0.6mm, 0.8mm, 1.25mm for the most distal lateral facet point, groove, and at the most distal point of lateral femoral condyle, respectively) and a high rate of type 1 and 2 uncorrectable knee imbalance (30% and 40%, respectively). The incidence of distal lateral prosthetic overstuffing (trochlea and condyle) and uncorrectable knee imbalance were strongly to very strongly correlated with the DFJLO (r=0.53 to 0.89).

CONCLUSION

Conventional MA technique for TKA generates frequent lateral distal femoral prosthetic overstuffing and technically uncorrectable knee imbalance secondary to disregarding the DFJLO when adjusting the femoral component frontal and axial rotations, respectively.

LEVEL OF EVIDENCE

level 4.

The influence of spine-hip relations on total hip replacement: A systematic review

Sagittal pelvic kinematics along with spino-pelvic angular parameters have recently been studied by numerous investigators for their effect on total hip replacement (THR) clinical outcomes, but many issue of spine-hip relations (SHR) are currently unexplored. Therefore, our review aims at clarifying the following questions: is there any evidence of a relationship between articular impingement/dislocation risk in primary THR and (1) certain sagittal pelvic kinematics patterns, (2) pelvic incidence, and (3) types of SHRs? A systematic review of the existing literature utilising PubMed and Google search engines was performed in January 2017. Only clinical or computational studies published in peer-reviewed journals over the last five years in either English or French were reviewed. We identified 769 reports, of which 12 met our eligibility criteria. A review of literature shows that sagittal pelvic kinematics, but not the pelvic incidence, influences the risk of prosthetic impingement/dislocation. We found no study having assessed the relationship between this risk and the types of SHRs. Sagittal pelvic kinematics is highly variable among individuals and certain kinematic patterns substantially influences the risk of prosthetic impingement/dislocation. Recommendations for cup positioning are therefore switching from a systematic to a patient-specific approach, with the standing cup orientation Lewinneck safe zone progressively giving way to a new parameter of interest: the functional orientation of the cup. Based on a recently published classification for SHRs, We propose a new concept of "kinematically aligned THR" for the purposes of THR planning. Further studies are needed to investigate the relevance of such a classification towards the assumptions and hypothesis we have made. Level of evidence,- Level IV, systematic review of level III and IV studies.

Spine-hip relations add understandings to the pathophysiology of femoro-acetabular impingement: A systematic review

Relationship between hip pathoanatomy and symptomatic FAI has been reported to be weak. This is explained by the reciprocal interaction between proximal femur and acetabular anatomies, but potentially also by the individual spine-hip relations (SHR). The key-answer for a complete understanding of the pathophysiology of FAI might lie in the comprehension of the SHRs, which have not yet been fully addressed. Therefore we conducted a systematic review to answer the subsequent questions: Is there any evidence of a relationship between FAI and (1) sagittal pelvic kinematics, (2) pelvic incidence, and (3) types of SHRs? A systematic review of the existing literature utilizing PubMed and Google search engines was performed in December 2016. Only studies published in peer-reviewed journals over the last ten years in either English or French were reviewed. We identified 90 reports, of which 9 met our eligibility criteria. Review of literature shows Caucasian FAI patients have a pelvis with higher anterior tilt, lesser sagittal mobility, and lower pelvic incidence compared to healthy patients. We found no study having assessed the relationship between SHR and FAI. In order to help further investigations at answering questions 3 and 4, we have developed a classification for SHRs. The classification according spino-pelvic parameters allows identifying patient at risk regarding FAI occurrence. Higher anterior pelvic tilt in standing, sitting and squatting positions and lower pelvic incidence have been found to correlate with symptomatic FAI. Because defining the individual SHR might increase the understanding of the pathophysiology of hip impingement, we have developed a classification for SHRs.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Magnetophoretic manipulation in microsystem using carbonyl iron-polydimethylsiloxane microstructures

This paper reports the use of a recent composite material, noted hereafter i-PDMS, made of carbonyl iron microparticles mixed in a PolyDiMethylSiloxane (PDMS) matrix, for magnetophoretic functions such as capture and separation of magnetic species. We demonstrated that this composite which combine the advantages of both components, can locally generate high gradients of magnetic field when placed between two permanent magnets. After evaluating the magnetic susceptibility of the material as a function of the doping ratio, we investigated the molding resolution offered by i-PDMS to obtain microstructures of various sizes and shapes. Then, we implemented 500 μm i-PDMS microstructures in a microfluidic channel and studied the influence of flow rate on the deviation and trapping of superparamagnetic beads flowing at the neighborhood of the composite material. We characterized the attraction of the magnetic composite by measuring the distance from the i-PDMS microstructure, at which the beads are either deviated or captured. Finally, we demonstrated the interest of i-PDMS to perform magnetophoretic functions in microsystems for biological applications by performing capture of magnetically labeled cells.

Metal-on-metal hip resurfacing compared with 28-mm diameter metal-on-metal total hip replacement: a randomised study with six to nine years' follow-up

A total of 219 hips in 192 patients aged between 18 and 65 years were randomised to 28-mm metal-on-metal uncemented total hip replacements (THRs, 107 hips) or hybrid hip resurfacing (HR, 112 hips). At a mean follow-up of eight years (6.6 to 9.3) there was no significant difference between the THR and HR groups regarding rate of revision (4.0% (4 of 99) vs 5.8% (6 of 104), p = 0.569) or re-operation rates without revision (5.1% (5 of 99) vs 2.9% (3 of 104), p = 0.428). In the THR group one recurrent dislocation, two late deep infections and one peri-prosthetic fracture required revision, whereas in the HR group five patients underwent revision for femoral head loosening and one for adverse reaction to metal debris. The mean University of California, Los Angeles activity scores were significantly higher in HR (7.5 (sd 1.7) vs 6.9 (sd 1.7), p = 0.035), but similar mean Western Ontario and McMaster Universities Osteoarthritis Index scores were obtained (5.8 (sd 9.5) in HR vs 5.1 (sd 8.9) in THR, p = 0.615) at the last follow-up. Osteolysis was found in 30 of 81 THR patients (37.4%), mostly in the proximal femur, compared with two of 83 HR patients (2.4%) (p < 0.001). At five years the mean metal ion levels were < 2.5 μg/l for cobalt and chromium in both groups; only titanium was significantly higher in the HR group (p = 0.001). Although revision rates and functional scores were similar in both groups at mid-term, long-term survival analysis is necessary to determine whether one procedure is more advantageous than the other.

A tapered channel microfluidic device for comprehensive cell adhesion analysis, using measurements of detachment kinetics and shear stress-dependent motion

We have developed a method for studying cellular adhesion by using a custom-designed microfluidic device with parallel non-connected tapered channels. The design enables investigation of cellular responses to a large range of shear stress (ratio of 25) with a single input flow-rate. For each shear stress, a large number of cells are analyzed (500-1500 cells), providing statistically relevant data within a single experiment. Besides adhesion strength measurements, the microsystem presented in this paper enables in-depth analysis of cell detachment kinetics by real-time videomicroscopy. It offers the possibility to analyze adhesion-associated processes, such as migration or cell shape change, within the same experiment. To show the versatility of our device, we examined quantitatively cell adhesion by analyzing kinetics, adhesive strength and migration behaviour or cell shape modifications of the unicellular model cell organism Dictyostelium discoideum at 21 °C and of the human breast cancer cell line MDA-MB-231 at 37 °C. For both cell types, we found that the threshold stresses, which are necessary to detach the cells, follow lognormal distributions, and that the detachment process follows first order kinetics. In addition, for particular conditions' cells are found to exhibit similar adhesion threshold stresses, but very different detachment kinetics, revealing the importance of dynamics analysis to fully describe cell adhesion. With its rapid implementation and potential for parallel sample processing, such microsystem offers a highly controllable platform for exploring cell adhesion characteristics in a large set of environmental conditions and cell types, and could have wide applications across cell biology, tissue engineering, and cell screening.

A quorum-sensing factor in vegetative Dictyostelium discoideum cells revealed by quantitative migration analysis

Background

Many cells communicate through the production of diffusible signaling molecules that accumulate and once a critical concentration has been reached, can activate or repress a number of target genes in a process termed quorum sensing (QS). In the social amoeba Dictyostelium discoideum, QS plays an important role during development. However little is known about its effect on cell migration especially in the growth phase.

Methods and Findings

To investigate the role of cell density on cell migration in the growth phase, we use multisite timelapse microscopy and automated cell tracking. This analysis reveals a high heterogeneity within a given cell population, and the necessity to use large data sets to draw reliable conclusions on cell motion. In average, motion is persistent for short periods of time (), but normal diffusive behavior is recovered over longer time periods. The persistence times are positively correlated with the migrated distances. Interestingly, the migrated distance decreases as well with cell density. The adaptation of cell migration to cell density highlights the role of a secreted quorum sensing factor (QSF) on cell migration. Using a simple model describing the balance between the rate of QSF generation and the rate of QSF dilution, we were able to gather all experimental results into a single master curve, showing a sharp cell transition between high and low motile behaviors with increasing QSF.

Conclusion

This study unambiguously demonstrates the central role played by QSF on amoeboid motion in the growth phase.

Measurement of the depth of maximum of extensive air showers above 10{18} eV

We describe the measurement of the depth of maximum, X{max}, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106{-21}{+35}) g/cm{2}/decade below 10{18.24+/-0.05} eV, and (24+/-3) g/cm{2}/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm{2}. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.

Multi-luminescent hybrid gadolinium oxide nanoparticles as potential cell labeling

This manuscript analyses the use of newly developed hybrid gadolinium oxide nanoparticles as cell-labeling tracers. The nanoparticles are core-shell particles composed of a core of gadolinium oxide of [2-4] nm and a protecting shell of polysiloxane [1-3 nm] where different organic dyes (fluoresceine isothiocyanate (FITC) or rhodamine B isothiocyanate (RBITC)) are embedded. They are functionalized with poly(ethylene glycol)bis(carboxymethyl) to ensure their colloidal stability in biological buffers. These particles are potential multi-labeling tracers (magnetic and optical). In this paper, we show by optical imaging that they can be efficiently internalized in cells without cell alteration. The in-vitro uptake of the nanoparticles was followed in two cell lines (human fibroblasts and a human adenocarnima cell lines MCF7 cells). Nanoparticles distribution within cells was analysed by confocal analysis, and gadolinium concentration within cells was quantified by mass spectrometry (ICP-MS analysis). Nanoparticles uptake is found to be fast and efficient for both cell lines, with fluorescent labeling visible after 10 min of incubation whatever the nature of the fluorophore. The fluorescent intensity is mainly found as concentrated dots in the perinuclear region of the cells and decreases with the number of days in culture, but is still easily detectable after 3 days in culture. No significant effect on cell growth was detected. Finally, we show in this study the protective effect of the polysiloxane layer: encapsulation of RBITC within the polysiloxane shell, leads to a better photostability of this low cost dye than Cy3 and even reach a level comparable to Alexa 595. With their high photostability and long-lasting contrast properties, these hybrid luminescent nanoparticles appears thus as a versatile solution to assess multiple cell fate both in in-vitro cell model as well as in-vivo.

The MRI assessment of intraurethrally--delivered muscle precursor cells using anionic magnetic nanoparticles

Autografting of cultured myogenic precursor cells (MPC) is a therapeutic strategy for muscle disorders, including striated urethral sphincter insufficiency. Implantation of myofibers with their satellite cells into the urethra is a recently described method of MPC transfer aimed at generating a new sphincter in incontinent patients. In this study, we magnetically labeled muscle implants with dextran-free anionic iron oxide nanoparticles (AMNP). The aim was to evaluate the biocompatibility of the labeling procedure and its utility for non-invasive MRI follow-up of cell therapy in a female pig model. After adsorption of AMNP to the implant surface, various cell types, including MPC, were magnetically labeled within the implants. Magnetic labeling did not affect cell proliferation or differentiation. Autograft detection in vivo by 0.3-T MRI was possible for up to 1 month. Ex vivo, Perl's, anti-desmin and anti-myosin heavy chain staining confirmed the co-localization of AMNP and regenerated myofibers. AMNP labeling was thus useful for locating myofiber implant autografts in vivo and for ex vivo monitoring of the biology of this cell transfer method.

Observation of the suppression of the flux of cosmic rays above 4 x 10 (19) eV

The energy spectrum of cosmic rays above 2.5 x 10;{18} eV, derived from 20,000 events recorded at the Pierre Auger Observatory, is described. The spectral index gamma of the particle flux, J proportional, variantE;{-gamma}, at energies between 4 x 10;{18} eV and 4 x 10;{19} eV is 2.69+/-0.02(stat)+/-0.06(syst), steepening to 4.2+/-0.4(stat)+/-0.06(syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz'min.

Changes in the magnitude and distribution of forces at different Dictyostelium developmental stages

The distribution of forces exerted by migrating Dictyostelium amebae at different developmental stages was measured using traction force microscopy. By using very soft polyacrylamide substrates with a high fluorescent bead density, we could measure stresses as small as 30 Pa. Remarkable differences exist both in term of the magnitude and distribution of forces in the course of development. In the vegetative state, cells present cyclic changes in term of speed and shape between an elongated form and a more rounded one. The forces are larger in this first state, especially when they are symmetrically distributed at the front and rear edge of the cell. Elongated vegetative cells can also present a front-rear asymmetric force distribution with the largest forces in the crescent-shaped rear of the cell (uropod). Pre-aggregating cells, once polarized, only present this last kind of asymmetric distribution with the largest forces in the uropod. Except for speed, no cycle is observed. Neither the force distribution of pre-aggregating cells nor their overall magnitude are modified during chemotaxis, the later being similar to the one of vegetative cells (F(0) approximately 6 nN). On the contrary, both the force distribution and overall magnitude is modified for the fast moving aggregating cells. In particular, these highly elongated cells exert lower forces (F(0) approximately 3 nN). The location of the largest forces in the various stages of the development is consistent with the myosin II localization described in the literature for Dictyostelium (Yumura et al.,1984. J Cell Biol 99:894-899) and is confirmed by preliminary experiments using a GFP-myosin Dictyostelium strain.

Upper limit on the diffuse flux of ultrahigh energy tau neutrinos from the Pierre Auger Observatory

The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from nu(tau) charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of nu(tau) at EeV energies. Assuming an E(nu)(-2) differential energy spectrum the limit set at 90% C.L. is E(nu)(2)dN(nu)(tau)/dE(nu)<1.3 x 10(-7) GeV cm(-2) s(-1) sr(-1) in the energy range 2 x 10(17) eV< E(nu)< 2 x 10(19) eV.

Aortic aneurysms in a rat model: in vivo MR imaging of endovascular cell therapy

PURPOSE

To prospectively evaluate in rats whether magnetic cell labeling can be used to noninvasively assess the technical success of endovascular cell therapy for abdominal aortic aneurysms (AAAs).

MATERIALS AND METHODS

The study was approved by an institutional animal care and use committee. Vascular smooth muscle cells (VSMCs) labeled with iron oxide nanoparticles were seeded endovascularly in already formed AAAs. T2*-weighted gradient-echo and T2-weighted spin-echo magnetic resonance (MR) imaging was performed in vivo at 1.5 T before and 30 minutes after the injection of iron-loaded VSMCs (14 rats), nonlabeled VSMCs (three rats), or iron-free particles (three rats). Ten rats were euthanized shortly after the injection (day 0). Of the 10 remaining rats, which were seeded with iron-loaded cells, three were imaged on day 7 after cell delivery; three, on day 14; and four, on day 28; then they were euthanized. Ex vivo high-field-strength MR imaging of two AAAs was performed 28 days after cell delivery. Histologic examination of cross sections of all AAAs was performed. Statistical evaluations were performed with a nonparametric Wilcoxon correlation test.

RESULTS

Magnetic cell labeling did not alter the capability of VSMCs to stabilize the diameter of the aneurysms. T2*-weighted gradient-echo images showed areas of hypointense signal within the aortic wall immediately and up to 1 month after cell therapy. The mean signal intensity decreased significantly after cell delivery (from 2362 +/- 244 [standard deviation] before to 434 +/- 275 after delivery, P < .001). Areas of hypointense signal and iron-loaded VSMCs were colocalized in the area of aortic wall reconstruction at both high-field-strength MR imaging and histologic analysis.

CONCLUSION

MR imaging with magnetic cell labeling can be used to document endovascular cell delivery in already formed AAAs in rats.

Magnetic Targeting of Nanometric Magnetic Fluid–loaded Liposomes to Specific Brain Intravascular Areas: A Dynamic Imaging Study in Mice

PURPOSE

To prospectively determine, by using dynamic imaging, whether a magnet placed over a specific area of the mouse brain could target systemically administered rhodamine-labeled magnetic fluid-loaded liposomes (MFLs) to that brain region.

MATERIALS AND METHODS

Experiments were performed with a French Ministry of Agriculture permit and regional ethics committee authorization. In seven anesthetized C57BL/6 mice, a closed cranial window was implanted above the left parieto-occipital cortex. A laser-scanning confocal fluorescence microscope (LSCFM) was used to track the intravenously injected rhodamine-labeled MFLs within this cortical area, through the cranial window. The MFLs were video monitored for 2 minutes every 15 minutes for 1 hour after injection. A magnet was placed on the cranial window implanted in four mice, while no magnet was placed in three (control) mice. After dynamic in vivo imaging, static in vivo imaging was performed with a different LSCFM. Ex vivo fluorescence histologic analysis was then performed. Paired Student t testing was used to compare the cerebral blood flow and two-dimensional flow values before and 1 hour after MFL injection. For image analysis, intergroup comparisons were performed by using an independent t test.

RESULTS

In vivo video monitoring through the window revealed that the rhodamine-labeled MFLs accumulated in the mouse brain microvasculature exposed to the magnet-first within superficial brain venules and then within intracerebral venules-with no significant change in blood flow (P > .05). MFLs accumulated neither in the arterioles of the mice with a magnet nor in the arterioles of the control mice. Static in vivo imaging findings confirmed the microvascular localization of the rhodamine-labeled MFLs, and histologic findings specified their accumulation on the side of the magnet only.

CONCLUSION

Real-time in vivo imaging of rhodamine-labeled MFLs in the mouse brain cortex revealed that these nanosystems can be magnetically targeted, through microvessels, to selected brain areas.

Intraurethral transfer of satellite cells by myofiber implants results in the formation of innervated myotubes exerting tonic contractions

PURPOSE

We investigated a new method of muscle precursor cell transfer in the urethra for the treatment of urinary incontinence, consisting of implanting myofibers with their satellite cells.

MATERIALS AND METHODS

In preliminary experiments to test the regenerative capacities of satellite cells histological analysis was performed on days 7 and 30 after the implantation of myofiber cores in the urethra of 6 female pigs. In the main experiments 11 pigs underwent baseline urodynamics, followed by endoscopic destruction of the striated urethral sphincter located around the distal urethra (day 0). On day 30 circular myofiber strips in 7 experimental cases and adipocytes in 4 controls were implanted in the proximal urethra. Seven days later (day 37) 1 case was sacrificed to verify satellite cell activation. On day 60 urodynamics were performed without and with curarization. Urethral cryosections were immunostained for desmin (activated satellite cells), fast myosin heavy chain/bungarotoxin (myotubes/acetylcholine receptors), neurofilament/vesicular acetylcholine transporter (nerve endings) and CD45/CD68 (inflammatory response).

RESULTS

Preliminary histological studies revealed a myogenic process consisting of myofiber degeneration and satellite cell activation (day 7), followed by myotube formation replacing parental myofibers (day 30). In the main experiments endoscopic injury abolished striated urethral sphincter activity. Implantation of myofiber strips generated a pressure peak that decreased after curarization (mean+/-SEM 71.5+/-17.8 vs 33.5+/-14.8 cm H2O, p=0.031) and reappeared 60 minutes later, revealing that this action was tonic and under neural control. Nerve endings connected to the acetylcholine receptors of myotubes were observed on day 60. An inflammatory response was observed only on day 7 in the myofiber implantation group. Adipocyte implantation resulted in no significant intraurethral pressure changes.

CONCLUSIONS

Urethral implantation of myofibers regenerates as myotubes that exert tonic activity under neural control. This has potential clinical value as a means to create an additional striated urethral sphincter.