Evolution of xenoantibodies, after their depletion, in a non-immunosuppressed baboon.
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Animals↗
Biomedical subjects
F Marin
Publications and source records attributed to F Marin.
Quantification of the 3D relative movement of external marker sets vs. bones based on magnetic resonance imaging.
BACKGROUND: Most in vivo knee kinematic analyses are based on external markers attached to the shank and the thigh. Literature data show that markers positioning and soft tissues artifacts affect the kinematic parameters of the bones true movement. Most of the techniques of quantification used were invasive. The aim of the present study was to develop and apply a non-invasive methodology to compute the relative movement between the bones and the markers. METHODS: Magnetic resonance imaging acquisitions were performed on the right knee of eleven volunteers without knee injury. The subjects were equipped with external magnetic resonance imaging-compatible marker sets. A foot drive device allowed the subjects to perform an actively loaded knee extension. The whole volume of the subject's knee was processed for four sequentially held knee flexion positions during the knee movement. The bones and external marker sets geometry were reconstructed from magnetic resonance imaging images. Then a registration algorithm was applied to the bones and the relative movement of the thigh and shank marker sets with respect to their underlying bones was computed. FINDINGS: The protocol resulted in a good geometrical accuracy and reproducibility. Marker sets movement differ from that of the bones with a maximum of 22 mm in translation and 15 degrees in rotation and it affects the knee kinematics. INTERPRETATION: Marker sets relative movement modify the knee movement finite helical axes direction (range 10-35 degrees ) and localization (range 0-40 mm). The methodology developed can evaluate external marker set system to be used for kinematic analysis in a clinical environment.
Adult↗
Canard orbits in Fabry-Perot cavities induced by radiation pressure and photothermal effects.
A theoretical study of a high-finesse Fabry-Perot cavity considering radiation pressure and photothermal displacement is reported. We show that the competition between these two effects induces a different kind of dynamic behavior in such a system, consisting of canard orbits and excitability. The transition between the excitable regime and the canard oscillations, occurring through a supercritical Hopf bifurcation, appears in an order compatible with the van der Pol-FitzHugh-Nagumo equations. Besides its interest as a study of general nonlinear dynamics, the characterization of the effects described is critical for high sensitivity interferometric displacement measurements as those employed for gravitational waves detection.
Journal Article↗
Can a finite set of knee extension in supine position be used for a knee functional examination?
The kinematic magnetic resonance imaging technique has been developed to provide a functional examination of the knee. Technical limitations require this examination to be performed in supine position, and the knee motion is represented by an assembly of static positions at different knee angles. However, the main knee function is to support the body weight and perform continuous motion, e.g. parallel squat. Our study quantified the knee kinematics of 20 healthy subjects in different motion conditions (finite and continuous) and in different mechanical conditions (continuous unloaded and continuous loaded). We evaluated the angular and localisation difference of a finite helical axis of the knee motion for parallel squat, continuous knee extension in supine position and the finite set of knee extension in supine position. We found large inter-individual dispersion. The majority of subjects had equivalent knee kinematics between continuous knee extension and the finite set of knee extension in supine position, but not between continuous knee extension in supine position and the parallel squat. Therefore, results from a functional examination of a finite set of knee extensions in supine position do not represent the knee motion in a parallel squat. Our results suggest that functional examination of the knee from magnetic resonance imaging do not necessarily reflect the physiological kinematics of the knee. Further investigation should focus on a new magnetic resonance imaging acquisition protocol that allows image acquisition during weight bearing or includes a special device which reproduces the loaded condition.
Adult↗
[Diffusion weighted MRI of spine tumors].
PURPOSE: To evaluate the contribution of diffusion weighted MR imaging in malignant spine pathology. Materials and methods. Between February 2004 and January 2005, 49 patients (43 to 86 years old) were included. Three groups were made: osteoporotic collapses (n = 13), malignant collapses (n = 15) and malignant spine lesions (n = 21). The MRI (Symphony 1.5T) allowed SENSE imaging. After conventional MRI examination (T1, T2 fat sat, T1 with Gadolinium), all patients underwent diffusion weighted imaging (Spin Echo) with variable b values: 0, 250, 500, 750 and 1000. The diffusion sequence lasted 2 min 29 s. The Apparent Diffusion Coefficient (ADC) was calculated automatically. The analysis was qualitative (signal study b = 1,000 mm2/s) and quantitative (ADC measurement). RESULTS: The image quality was good except for some cervical examinations. Qualitative analysis did not show a difference between benign and malignant lesions. Quantitative results are: malignant spine lesion (mean ADC = 0.826 10-3 s/mm2), malignant spinal collapses (mean ADC = 0.912 10-3 s/mm2) and benign spinal collapses (mean ADC = 1.497 10-3 s/mm2). There was overlapping results between benign and malignant lesion. The statistical study showed a significant difference (t test with p < 1/10 000). For an ADC threshold value of 1.089 (malignant lesion ADC < 1.089), ROC curve showed a specificity = 80% and a sensitivity = 83.3%. CONCLUSION: Performing diffusion weighted imaging of the spine is easy with new MR technology. The ADC measurement of spine lesion provides important additional information, but does not serve as a substitute for the routine MRI sequences. In the future, it could become an important point in this difficult diagnosis.
Adult↗
[Synovial biopsy under US guidance: technical considerations and results].
PURPOSE: To describe and assess ultrasound (US) guided biopsy of peripheral joint synovial membrane. METHOD: Between January 2002 and January 2005, 83 patients have undergone biopsies of synovial membrane performed under ultrasonographic guidance, as a diagnostic procedure for monoarthritis of unknown etiology. After synovial thickening was confirmed by US examination, the optimal approach to the joint was decided in accordance with maximal synovial thickening localization and adjacent anatomic structures. The absence of complications related to the biopsy was verified by continuous ultrasonographic scanning during and immediately after the procedure. The procedure was rated as successful if synovial tissue was identified by histologic examination of the biopsy specimen. Success rate of the procedure was compared to the fluoroscopic guided biopsy success rate that was formely published in medical literature. RESULTS: Synovial tissue was obtained in 78 cases (94%) (shoulder (100%), elbow (75%), wrist (85.7%), hip (88.2%), knee (97%), ankle (100%). No complication occurred. CONCLUSION: US guided biopsy of peripheral joint synovial membrane is a safe and effective technique that has multiple advantages compared to fluoroscopic guided procedure.
Adolescent↗
[Hip dysplasia and misalignment in patients aged 20-50 years].
Anterior hip pain in young adult (20 to 50) has two main causes: secondary osteo-arthritis on development dysplasia of the hip, and femoro-acetabular impigement (FAI). This symposium had two parts: the first one analyses long-term results of non-prosthetic surgery (283 osteotomies and shelfs at 15 years FU). The second part concerned the different syndromes with acute anterior hip pain, especially due to FAI and to labral tears.In hip dysplasia, 56 shelf operations, 100 proximal femoral varus osteotomies associated or not with a shelf arthroplasty,and 127 Chiari osteotomies were examined with 10 years minimum follow-up. Only 15% of patients were lost at follow-up before 10 years and average follow-up was 15 years. Results were considered as satisfactory when the Merle d'Aubigne rating was 15/18 or more. The 3 main factors of good prognosis were: a complete correction of both femoral and acetabular dysplasia; age at operation under 40; a moderate arthritis (grade I or II according to De Mourgues and Patte). In single acetabular dysplasia with 3 favorable prognosis factors(no coxa valga, age under 40, arthritis 1 or 2), 85% good results were achieved at 15 years. When patients were over 40 at operation, or in arthritis grade over 2, only 55% of good results were observed. Varus osteotomies, associated or not with shelf arthroplasties, achieved also 85% goods results at 15 years when the 3 favorable prognosis factors were present. Similar good results were also obtained by Chiari osteotomy, but this operation was associated with 12% complications, and more that 25% of lasting limping. Therefore, with 85% good results at 15 years (and often over 20 years), non prosthetic surgery performed at 30-35 years, achieved better functional results than total hip arthroplasty, longer lasting, and not jeopardizing any further possibility of prosthetic surgery.As concerns acute anterior pain of the hip, the clinical and imaging patterns of the different syndromes have been precised: femoro-acetabular impigement by cam (or by pincer), labral tears in hip dysplasia. There were distinguished from the other secondary impigements, for example by acetabular malposition due to pelvis anteflexion or by other hip diseases: overuse arthritis, coxa retrorsa, etc. Several examples of typical syndromes were presented to support the recommended imaging techniques. The results of the speakers with different surgical treatments were reported as well as concerns open surgery than arthroscopic treatment (60 cases).
Acetabulum↗
Upper limits on gravitational-wave emission in association with the 27 Dec 2004 giant flare of SGR1806-20.
At the time when the giant flare of SGR1806-20 occurred, the AURIGA "bar" gravitational-wave (GW) detector was on the air with a noise performance close to stationary Gaussian. This allows us to set relevant upper limits, at a number of frequencies in the vicinities of 900 Hz, on the amplitude of the damped GW wave trains, which, according to current models, could have been emitted, due to the excitation of normal modes of the star associated with the peak in x-ray luminosity.
Journal Article↗
Intradiscal injection of oxygen-ozone gas mixture for the treatment of cervical disc herniations.
For disc herniations the use of open surgical approaches is reduced since new percutaneous methods allowing shrinkage of the disc and improvement of the radicular function are gaining interest. Studies on the spontaneous disappearance of disc fragments have demonstrated autoimmune responses with a chronic inflammatory reaction. Also radicular pain has been shown to be mostly due to biochemical mechanisms. Researchers in different fields surprisingly noticed that a brief, calculated, oxidative stress by ozone administration may correct a persistent imbalance due to excessive, chronic oxidative injury. Oxygen-ozone gas injection in painful patients has a dramatic effect on clinical symptoms. On these bases the intradiscal injection of oxygen-ozone gas has been conceived. We report the treatment on a series of patients affected by cervical disc pathology, treated by intradiscal injection of oxygen-ozone gas mixture. The effects both on pain and on radicular dysfunction are impressive. The morphological effect of the treatment was also evaluated by pathological examination.
Adult↗
[Periosteal hemangioma of the distal humeral: case report and review of the literature].
The authors report a case of periosteal cavernous hemangioma of the distal humeral. They describe the imaging findings of hemangiomas of long tubular bones and discuss their differential diagnosis.
Adolescent↗
[Vertebral trabecular network analysis on CT images].
PURPOSE: Comparing texture analysis, density measurement and visual quantification of trabecular network on spine CT images, to better evaluate bone architecture in osteoporosis. METHOD AND MATERIALS: Seventeen patients, aged 19 to 84 years, were included. One patient presented osteoporotic fractures. High resolution computed tomographic (HR-CT) images of the third lumbar vertebra were acquired using a Somatom 4 plus CT (Siemens) in a strict axial orientation with FOV of 12 cm and slice thickness of 1 mm. The size of the Region Of Interest was 1,6 cm(2). Three analyses were performed on this ROI: Density (in Hounsfield Unity), texture analysis (run length) and features inspired from bone histomorphometry (Bone Volume/Tissue Volume). RESULTS: Density measurement, run length methods and BV/TV provided consistent results with regards to age. Indeed density, run length and BV/TV results were lower for older patients with more advanced bone trabeculra alterations. CONCLUSION: Only BV/TV and run length parameters seemed to show additional information on trabecular network architecture. The contribution of these two measurements to diagnose and classify osteoporosis will be the goal of a clinical study.
Adult↗
Finite helical axes of motion are a useful tool to describe the three-dimensional in vitro kinematics of the intact, injured and stabilised spine.
The finite helical-axes method can be used to describe the three-dimensional in vitro kinematics of the spine. However, this method still suffers from large stochastic calculation errors and poorly conceived visualisation techniques. The aim of the present study, therefore, was to improve the currently used finite helical axes description, by use of a less error-prone calculation algorithm and a new visualisation technique, and to apply this improved method to the study of the three-dimensional in vitro kinematics of the spine. Three-dimensional, continuous motion data of spinal motion segments were used to calculate the position and orientation of the finite helical axes (FHAs). The axes were then projected on plane antero-posterior, lateral and axial radiographs in order to depict the relation to the anatomy of each individual specimen. A hinge joint was used to estimate the measurement error of data collection and axes calculation. In an exemplary in vitro experiment, this method was used to demonstrate the ability of a prosthetic disc nucleus to restore the three-dimensional motion pattern of lumbar motion segments. In the validation experiment with the hinge joint, the calculated FHAs were lying within +/-2.5 mm of the actual joint axis and were inclined relative to this axis at up to +/-1.5 degrees . In the exemplary in vitro experiment, the position and orientation of the FHAs of the intact specimens were subject to large inter-individual differences in all loading directions. Nucleotomy of the lumbar segments caused the axes to spread out, indicating complex coupled motions. The implantation of the prosthetic disc nucleus, for the most part, more than reversed this effect: the axes became oriented almost parallel to each other. The experiments showed that the present improved description of finite helical axes is a valid and useful tool to characterise the three-dimensional in vitro kinematics of the intact, injured and stabilised spine. The main advantage of this new method is the comprehensive visualisation of joint function with respect to the individual anatomy.
Algorithms↗
Discriminative capacity of calcaneal quantitative ultrasound and of osteoporosis and fracture risk factors in postmenopausal women with osteoporotic fractures.
Bone fragility fractures constitute the principal complication of osteoporosis. The identification of individuals at high risk of sustaining osteoporotic fractures is important for implementing preventive measures. The purpose of this study is to analyze the discriminative capacity of a series of osteoporosis and fracture risk factors, and of calcaneal quantitative ultrasound (QUS), in a population of postmenopausal women with a history of osteoporotic fracture. A cross-sectional analysis was made of a cohort of 5195 women aged 65 or older (mean +/- SD: 72.3 +/- 5.4 years) seen in 58 primary care centers in Spain. A total of 1042 women (20.1%) presented with a history of osteoporotic fracture. Most fractures (93%) were non-vertebral. Age-adjusted odds ratios corresponding to each decrease in one standard deviation of the different QUS parameters ranged from 1.47 to 1.55 (P < 0.001) for fractures. The age-adjusted multivariate analysis yielded the following risk factors independently associated with a history of osteoporotic fracture: number of fertile years, a family history of fracture, falls in the previous year, a history of chronic obstructive airway disease, the use of antiarrhythmic drugs, and a low value for any of the QUS parameters. The area under the receiver operating characteristic curve of the best model was 0.656. In summary, a series of easily assessable osteoporotic fracture risk factors has been identified. QUS was shown to discriminate between women with and without a history of fracture, and constitutes a useful tool for assessing fracture risk. Various of the vertebral and hip fracture risk factors frequently cited in North American and British populations showed no discriminative capacity in our series--thus suggesting that such factors may not be fully applicable to our population and/or to the predominant type of fractures included in the present study.
Aged↗
Anterior cruciate ligament rupture translates the axes of motion within the knee.
OBJECTIVE: To quantify the dynamic effects of anterior cruciate ligament deficiency on human knee joint motion. DESIGN: Three-dimensional motion was assessed by measuring the kinematics of intact and anterior cruciate ligament deficient knee joint specimens during simulated flexion-extension cycles. BACKGROUND: It is known that the anterior cruciate ligament plays an important role in controlling three-dimensional knee joint motion. Nevertheless, dynamic effects of deficiency are not fully understood. METHODS: Six cadaveric knees were tested in a knee joint motion and loading apparatus prior to and after anterior cruciate ligament resection. To determine if the kinematic results depended on additional loading, internal and external rotation moments of 3.4 Nm were axially applied to the tibia. The kinematics were analysed in terms of finite helical axes. RESULTS: Sectioning the anterior cruciate ligament had little effect on the orientations of the finite helical axes. However, applying moments did affect the axes orientation. In contrast, relative translations of the axes were significantly affected by the deficiency for all rotational moments applied. Referring to the individual knee anatomy the largest translation of 12.5 mm (median) occurred in medial/lateral direction. CONCLUSIONS: Anterior cruciate ligament rupture primarily causes a translation of the finite helical axes in medial/lateral direction. Consequently, increased anterior excursion of the tibia occurs (subluxation) and therefore dynamic instability.
Adult↗
[Evaluation of the efficacy of CT guided thoracic sympatholysis to treat palmar hyperhidrosis].
PURPOSE AND METHOD: Palmar hyperhidrosis is a pathological condition characterized by overperspiration caused by any stress or emotion. We have evaluated the results of 101 CT guided sympatholysis procedures performed on 50 patients suffering from primary palmar hyperhydrosis. RESULTS: Mean follow up was 50 Months (6 Months to 8 Years) for 87 procedures with immediate good results in 46 patients. Using actuarial analysis, 62% of patients had persistent good results after 50 Months. Complications included one case of small pneumothorax requiring no treatment and one case of vagal syndrome. Pain or thoracic discomfort was reported by 14 patients and was relieved by aspirin within 24 hours. Six patients developed a Horner's syndrome that resolved within a few weeks and six other patients developed moderate compensatory overperspiration over the face, thorax or contralateral arm. CONCLUSION: Based on our results, CT guided sympatholysis provides results similar to endoscopic thoracic sympathectomy and is associated with fewer risks.
Adolescent↗
Identification of a new HLA-DRB1 allele in three members of an Italian family.
Abstract A new human leucocyte antigen (HLA)-DRB1 allele, HLA-DRB1*1149, has been identified in three members of an Italian family during routine sequence based typing. This new allele differs from HLA-DRB1*110101 only for a single nucleotide substitution at position 113 of exon 2 resulting in an amino acid change from Valine (GTG) to Alanine (GCG) at codon 38.
Alleles↗
Nonlocal pulse shaping with entangled photon pairs.
Nonlocal shaping effects in the time or spectral profiles of an entangled photon pair emerging from a pulsed parametric down-converter are observed by spectrally or temporally filtering one of the twin beams. In particular, we demonstrate the appearance of fourth-order ("ghost") interference fringes in the spectrum of one beam conditioned by photodetection at the output of an unbalanced Michelson interferometer placed in the path of the other beam. The coherence time of the pump is the limiting factor for the sharpness of the details in the shaped biphoton spectrum.
Journal Article↗
Correction of axis misalignment in the analysis of knee rotations.
The Cardanic or Eulerian description is the most commonly used method for the description of in vivo knee rotation. It is based on the determination of external anatomical landmarks used for the decomposition of the position of the tibia relative to the femur by three rotations about three pre-defined axes. However, the in vivo localisation of external anatomical landmarks is known to be difficult and subjective. Even a small mislocalisation may lead to dramatic consequences: the Cardanic description may become irreproducible and angle values may be overestimated. This error is well documented in the literature and known as the "cross-talk effect". Therefore this study proposes an additional calibration step of the classic Cardanic description by a reorientation procedure of rotation axes. The procedure is based on biomechanical constraints of knee kinematics as they appear during a knee squat exercise using the finite helical axis (FHA) method and is independent of anatomical landmark. The method was validated with the help of a special set-up modelling a perfect knee. Furthermore, an inter-session reliability study was performed involving tests on two healthy subjects during knee squat exercises. We found that the reorientation procedure was more reproducible than the classic Cardanic description. We observed a maximum inter-session difference of 37.1 degrees for the adduction angle obtained with the classic Cardanic description. In contrast, the maximum angle difference obtained with the reorientation procedure was less than 10 degrees.
Adult↗