Regulation of osteoprotegerin pro- or anti-tumoral activity by bone tumor microenvironment

Tumor development in bone is often associated with fractures, bone loss and bone pain, and improvement is still needed in therapeutic approaches. Bone tumors are related to the existence of a vicious cycle between bone resorption and tumor proliferation in which the molecular triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL) plays a pivotal role. RANKL, a member of the TNF superfamily, is one of the main inducers of bone resorption. Its soluble receptor OPG represents a promising therapeutic candidate as it prevents bone lesions and inhibits associated tumor growth. However, its therapeutic use in bone tumors remains controversial due to its ability to bind and inhibit another member of the TNF superfamily, TNF related apoptosis inducing ligand (TRAIL), which is a potent inducer of tumor cell apoptosis. Through its heparin binding domain, OPG is also able to bind proteoglycans present in the bone matrix. This paper is an overview of the involvement of the micro-environment, as represented by the balance of RANKL/TRAIL and the presence of proteoglycans in the regulation of OPG biological activity in bone tumors.

Overexpression of Follistatin in Human Myoblasts Increases Their Proliferation and Differentiation, and Improves the Graft Success in SCID Mice

Duchenne muscular dystrophy is caused by the absence of functional dystrophin, leading to the myofiber membrane instability and progressive muscle atrophy. Myoblast transplantation in dystrophic muscles is a potential therapy, as it permits the long-term restoration of dystrophin expression in transplanted muscles. However, the success of this approach is limited by the short period of muscle repair following myoblast transplantation. Myostatin, a powerful inhibitor of muscle growth, is involved in terminating the period of muscle repair following injury by reducing myoblast proliferation and differentiation. Follistatin forms a complex with myostatin, preventing its interaction with its receptor and thus blocking the myostatin signal. Here, we used a lentivirus to overexpress the follistatin protein in normal myoblasts to block the myostatin signaling. We measured the potential of transduced myoblasts to proliferate and to form multinucleated myotubes in vitro. And finally, we considered the engraftment success of those transduced myoblasts in comparison with control cells in vivo within SCID mice TA muscle. Our results first confirmed the overexpression of follistatin into lentivirus transduced myoblasts, and second showed that the overexpression of the follistatin in normal human myoblasts improved in vitro their proliferation rate by about 1.5-fold after 96 h and also their differentiation rate by about 1.6- and 1.8-fold, respectively, in the absence and in the presence of recombinant myostatin. Finally, our data demonstrated that the engraftment of human normal myoblasts overexpressing the follistatin protein into SCID mouse muscles was enhanced by twofold.

Towards an accurate and robust method based on fuzzy logic principles for the reconstruction and quantification of large volumes from MR and CT images

The authors have previously evaluated a new method of volume reconstruction and quantification from MR images, based on fuzzy logic (FL) principles. The technique is evaluated here for larger and more complex structures by investigating its accuracy and robustness using MR and CT images. Four large (50-71 cm(3)) and complex (e.g. mimicking a prostate) structures were created and imaged on MR and CT scanners, both with increasing slice thickness. Contours were delineated to generate 112 volumes. MR and CT images were processed using the FL method and a "classical" method of reconstruction on research software. In addition, the CT images were also processed on commercial virtual simulation software. Calculated volumes were compared with actual volumes. The mean +/- standard deviation of the relative variations in calculated target volume using the FL method was found to be 4.4%+/-2.8%, whereas with the "classical" method it was 23.7%+/-6% from axial MR images and 23.3%+/-9.8% from CT images. With the "classical" method, the relative variations in calculated volumes rise with increasing slice thickness, and the displayed volumes show deformations in the longitudinal direction. With the FL method, the volume calculation is not sensitive to the slice thickness and so the deformations are minimal. When used with MR images, our FL method of volume reconstruction is accurate and robust with respect to changes in slice thickness. For CT images, the results are encouraging but some work is still needed to improve the accuracy of the FL method.

An easy-to-use phantom and protocol for weekly PET quality assessment: a multicenter study

The authors have developed a simple phantom and dedicated software for the quality assessment of positron emission tomography (PET) scanners. The phantom is a parallelepiped box filled with a relatively low activity 18FDG solution and in which simple test objects are placed. Various image quality parameters are checked, including signal-to-noise ratio, image uniformity, slice thickness, slice sensitivity profile, spatial resolution, and dose calibration accuracy. Automatic image analysis consists in detecting surfaces and objects, defining regions of interest, acquiring reference point coordinates, and establishing gray-scale profiles. The total time needed for quality assessment (preparation and image acquisition) is less than 15 min with 37 MBq (1 mCi) 18FDG. The system's ease of use encourages frequent image quality assessment-for example, the comparison of PET scanners in interdepartment studies and the monitoring and evaluation of possible drifts over time. By way of an example, the authors present weekly quality assessment results obtained over up to 7 months at four PET facilities.

[Dosimetric evaluation of an automatic segmentation tool of pelvic structures from MRI images for prostate cancer radiotherapy]

PURPOSE

An automatic segmentation tool of pelvic structures from MRI images for prostate cancer radiotherapy was developed and dosimetric evaluation of differences of delineation (automatic versus human) is presented here.

MATERIALS AND METHODS

CTV, rectum and bladder were defined automatically and by a physician in 20 patients. Treatment plans based on "automatic" volumes were transferred on "manual" volumes and reciprocally. Dosimetric characteristics of PTV (V(95), minimal, maximal and mean doses), rectum (V(50), V(70), maximal and mean doses) and bladder (V(70), maximal and mean doses) were compared.

RESULTS

Automatic delineation of CTV did not significantly influence dosimetric characteristics of "manual" PTV. Rectal V(50) and V(70) were not significantly different; mean rectal dose is slightly superior (43.2 versus 44.4Gy, p=0.02, Student test). Bladder V(70) was significantly superior too (19.3 versus 21.6, p=0.004). Organ-at-risk (OAR) automatic delineation had little influence on their dosimetric characteristics; rectal V(70) was slightly underestimated (20 versus 18.5Gy, p=0.001).

CONCLUSION

CTV and OAR automatic delineation had little influence on dosimetric characteristics. Software developments are ongoing to enable routine use and interobserver evaluation is needed.

MRI alone simulation for conformal radiation therapy of prostate cancer: technical aspects

The value of MRI in defining target volumes and organs at risk is established. Numerous difficulties appear to stand in the way of using MRI alone in dose planning, with the result that this imaging modality is used in most cases in conjunction with computerized X-ray tomography (CT). The aim of this paper is to appreciate these difficulties: geometrical distortion, chemical shifts, dosimetric accuracy. Geometrical distortion measurements were carried out on two 1.5 T MR scanners and the effect of chemical shift and magnetic susceptibility were evaluated in volunteers. The effect on dosimetric calculations of uncertainty in determining electron densities was evaluated too. Geometrical distortion remained at small values: less than 2 mm and 3 mm for field of view of 20 cm and 45 cm. The chemical shift and magnetic susceptibility values obtained, ranging from 0.3 to 3 mm, were well below the theoretical values. The assignment of relative electron densities to only two structures in MR images seems to permit dose planning that is identical with that obtained with CT. None of the technical obstacles mentioned represents a stumbling block. The access to MRI facility could represent a persisting problem.

A new method based on both fuzzy set and possibility theories for tumor volume segmentation on PET images

A new automatic method for tumor volume segmentation on PET images has been developed. The method introduced in this paper is based on previous works in MRA segmentation and involves both fuzzy set and possibility theories. Visual results prove the method efficiency which is confirmed by obtained Jaccard index.

[Interventional MR imaging: state of the art and technological advances]

Due to its excellent soft tissue contrast and lack of ionizing radiation, MR imaging is well suited for interventional procedures. MRI is being increasingly used for guidance during percutaneous procedures or surgery. Technical advances in interventional MR imaging are reviewed in this paper. Ergonomical factors with improved access to patients as well as advances in informatics, electronics and robotics largely explain this increasing role. Different elements are discussed from improved access to patients in the scanners to improved acquisition pulse sequences. Selected clinical applications and recent publications will be presented to illustrate the current status of this technique.

Polymer gel dosimetry for synchrotron stereotactic radiotherapy and iodine dose-enhancement measurements

Synchrotron stereotactic radiotherapy (SSR) is a radiotherapy technique that makes use of the interactions of monochromatic low energy x-rays with high atomic number (Z) elements. An important dose-enhancement can be obtained if the target volume has been loaded with a sufficient amount of a high-Z element, such as iodine. In this study, we compare experimental dose measurements, obtained with normoxic polymer gel (nPAG), with Monte Carlo computations. Gels were irradiated within an anthropomorphic head phantom and were read out by magnetic resonance imaging. The dose-enhancement due to the presence of iodine in the gel (iodine concentration: 5 and 10 mg ml(-1)) was measured at two radiation energies (35 and 80 keV) and was compared to the calculated factors. nPAG dosimetry was shown to be efficient for measuring the sharp dose gradients produced by SSR. The agreement between 3D gel dosimetry and calculated dose distributions was found to be within 4% of the dose difference criterion and a distance to agreement of 2.1 mm for 80% of the voxels. Polymer gel doped with iodine exhibited higher sensitivity, in good agreement with the calculated iodine-dose enhancement. We demonstrate in this preliminary study that iodine-doped nPAG could be used for measuring in situ dose distributions for iodine-enhanced SSR treatment.

Induction of Anoikis following myoblast transplantation into SCID mouse muscles requires the Bit1 and FADD pathways

Seventy-five percent of the myoblasts transplanted in the mouse muscle die during the first 4 days following transplantation. The purpose of this study was to determine if anoikis plays a role in this phenomenon. Survival and proliferation of myoblasts in vitro were determined by Hoescht-PI labeling and cell counts respectively. In vivo cell survival and proliferation were quantified by injecting human male myoblasts labeled with (14)C-thymidine in SCID mouse muscles. Survival and proliferation of the transplanted myoblasts were evaluated by scintigraphy and quantitative PCR of human Y chromosomal DNA. Inclusion of the extracellular matrix protein fibronectin enhanced transplanted myoblast survival by 1.7-fold while vitronectin improved their proliferation by 1.8-fold. Reductions in FADD and Bit1 expression reduced anoikis in vitro and improved the injected myoblast survival in vivo. Ectopic expression of the anti-apoptotic protein Bcl-2 completely abolished myoblast anoikis in vitro and enhanced cell survival by 3.1-fold in vivo. Cell death following transplantation appears to me mediated in part by anoikis. Inclusion of extracellular matrix proteins enhanced both survival and proliferation. Reduced expression of the proapoptotic proteins Bit1 and FADD or overexpression of Bcl-2 improved myoblast survival.

Interventional therapy procedures assisted by medical imaging and simulation. The experience of U 703 Inserm (Lille France)

Since the early 1990s, minimally invasive techniques have been increasingly used in ever more and diversified fields of application. These techniques have some shared characteristics (predominant role of medical imaging, intensive use of new communication technologies, a multidisciplinary medical and scientific framework, etc.) but also shared specific problems (high-tech tools unfamiliar to the medical users, a major and long period of time for technological development, unavailability of training systems, difficulties in obtaining regulatory approval). For a long time, our Laboratory of Medical Physics (U 703 Inserm) has developed an innovative research activity in biomedical engineering in the field of assisted therapy, medical imaging and medical simulation. This paper presents the general context of interventional therapy procedures assisted by image and simulation and describes our scientific activities based on realistic objectives close to medical practice.

A 2D/3D matching based on a hybrid approach: improvement to the imaging flow for AVM radiosurgery

A new approach of registration in multimodal imaging has been developed. Modalities involved are Digital Subtracted Angiography (DSA, 2D) and Magnetic Resonance Angiography (MRA, 3D). Our approach is an hybrid one, mixing feature and intensity based approaches. This approach is based on the extraction of a anatomical referential common to both MRA and DSA. The results obtained prove the methods efficiency in a clinical context. This paper present the validation methodology to make it possible the replacement of the localization DSA examination by the diagnosis one, thus avoiding supplementary costs, lost time and medical hazards for the patient and for the medical staff.

A method to register intra-treatment ultrasound images to pre-treatment images of prostate

This paper describes a method to register ultrasound images (US) to pre-treatment images. The aim of the work is the information transfer between the pre-treatment imaging modality (MR or CT) and the intra-treatment imaging (US). Ultrasound images are spatially tracked by a stereo-vision system and the prostate boundaries are automatically extracted using a method that combines morphological and adaptive speckle suppression and a priori knowledge. MR/CT images are merged to construct a volume of pelvis using fuzzy logic algorithm and an MPR virtual slice corresponding to the orientation of the US image is generated from the volume. The prostate is segmented from the slice by a model-based method and rigidly registered by ICP algorithm to the US contour. Preliminary experiences gave satisfactory results with short computing time.

Lung liquid clearance in newborn lamb: MRI methods and preliminary results

To study the lung water clearance in vivo at the time of the birth, MR experiments were conducted on newborn lamb immediately after uterine incision deliverance. Images obtained with a fast spin echo sequence enable to quantify lung liquid each 5 minutes during 30 minutes then each 10 minutes for 1.5 hour. From the lung contours, pulmonary volume, pulmonary water, and spatial gradient of pulmonary water were studied. At 2 hours of life, the total pulmonary water content was still high and the liquid clearance was slower in the lower part of the lung. Air inflation increased the size of the distal airways and shifted liquid from the lung lumen towards the pulmonary interstitial tissue. The pulmonary water wash-out was belated and the passage to the aerial life was performed by progressive liberation of the superior pulmonary spaces, water flowing out by gravity toward the lower spaces.

Comparison between shifted Spearman rank correlation test and SPM in fMRI

A new improving method to compute Spearman rank correlation test has been developed. This method is based on the use of a response to stimulation delay referred by many authors. Visual results tend to prove the method efficiency which is confirmed by obtained overlap rates; moreover this method can easily be adapted in a clinical context.

Methicillin-resistant staphylococcal colonization in clinically normal dogs and horses in the community

AIMS

To evaluate the prevalence of methicillin-resistant staphylococcal (MRS) colonization in clinically normal dogs and horses in the community.

METHODS AND RESULTS

Three hundred clinically normal horses and 200 clinically normal dogs were enrolled. One nasal swab was collected from each horse. Two swabs were taken from each dog: (i) from an anterior nare, and (ii) a combination of the perineal area and 0.5 cm into the anus. Enrichment cultures were performed. Methicillin-resistant Staphylococcus aureus (MRSA) was not identified. Methicillin-resistant Staphylococcus intermedius (MRSI) was isolated from the nasal swab from three dogs. Methicillin-resistant coagulase negative staphylococci (MRCoNS) were isolated from 126/300 (42%) horses and 26/200 (13%) dogs.

CONCLUSIONS

At present MRSI is not considered to be a significant zoonotic concern; however, it may become an important pathogen in dogs. MRCoNS mostly cause disease in compromised human or animal hosts. However, these bacteria can serve as reservoirs of resistance determinants in the community, which could lead to the emergence of novel MRSA strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of the prevalence of MRS colonization in clinically normal dogs in a community setting. Continued surveillance is indicated to determine whether MRSA will emerge in the animal population and become a concern for animal disease and zoonotic infection.

Dystrophin expression in host muscle following transplantation of muscle precursor cells modified with the phiC31 integrase

Duchenne muscular dystrophy (DMD) is the most severe muscular dystrophy. It is caused by the absence of dystrophin in muscle fibers. The autologous transplantation of genetically corrected muscle precursor cells (MPCs) is a possible cure for DMD. A non-viral method of genetic modification was tested in this study. The co-transfection (nucleofection) of a phiC31 integrase and a transgene expressing plasmid in MPCs led to an increased stable expression in vitro. The stable expression of a small transgene (eGFP) in muscle fibers was initially demonstrated following the transplantation of the genetically modified cells. The stable expression of a truncated version of dystrophin as well as the full-length dystrophin fused with eGFP was then demonstrated in MPCs obtained from an mdx mice. The transplantation of these cells led not only to the expression of these fusion proteins in muscle fibers but also to the reconstitution of the dystrophin complex. Human MPCs were also genetically modified with a plasmid coding for the full-length human dystrophin gene fused with eGFP and transplanted in severe combined immuno deficient mice leading to the expression of eGFP dystrophin in muscle fibers. This work indicates that cell transplantation after correction of MPCs with phiC31 integrase is a possible approach to treat DMD.

Survival of Salmonella Copenhagen in food bowls following contamination with experimentally inoculated raw meat: effects of time, cleaning, and disinfection

There are concerns regarding the safety of feeding raw meat to household pets. This study demonstrated that Salmonella persists in food bowls that are inoculated with Salmonella-containing raw meat. Standard methods of cleaning and disinfection were minimally effective at eliminating Salmonella contamination.