Reevaluation of the diametral compression test for tablets using the flattened disc geometry.

Mechanical strength is an important critical quality attribute for tablets. It is classically measured, in the pharmaceutical field, using the diametral compression test. Nevertheless, due to small contact area between the tablet and the platens, some authors suggested that during the test, the failure could occur in tension away from the center which would invalidate the test and the calculation of the tensile strength. In this study, the flattened disc geometry was used as an alternative to avoid contact problems. The diametral compression on both flattened and standard geometries was first studied using finite element method (FEM) simulation. It was found that, for the flattened geometry, both maximum tensile strain and stress were located at the center of the tablet, which was not the case for the standard geometry. Experimental observations using digital image correlation (DIC) confirmed the numerical results. The experimental tensile strength obtained using both geometries were compared and it was found that the standard geometry always gave lower tensile strength than the flattened geometry. Finally, high-speed video capture of the test made it possible to detect that for the standard geometry the crack initiation was always away from the center of the tablet.

The SKG Mutation in ZAP-70 also Confers Arthritis Susceptibility in C57 Black Mouse Strains.

Various rodent models of arthritis are essential to dissect the full complexity of human rheumatoid arthritis (RA), a common autoimmune disease affecting joints. The SKG model of arthritis originates from a spontaneous mutation in ZAP-70 found in a BALB/c colony. This mutation affects T cell selection due to reduced TCR signalling, which allows leakage of self-reactive T cells from the thymus. To further expand the practical applicability of this unique model in arthritis research, we investigated the arthritogenicity of the SKG mutation in two common black mouse strains C57BL/6.Q and C57BL/10.Q and compared to BALB/c.Q. Mice retained the reduced TCR signalling characteristic of SKG.BALB/c mice, which leads to similar alteration in thymic selection. Importantly, mice also retained susceptibility to chronic arthritis after a single injection of mannan from Saccharomyces cerevisiae, with comparable prevalence and severity regardless of the genetic background. Further characterization of CD4(+) T cells revealed a similar bias towards IL-17 production and activated T cell phenotype in all SKG strains compared to respective wild type controls. Finally, transfer of SKG thymocytes conferred susceptibility to recipients, which confirm the intrinsic defect and pathogenicity of T cells. Overall, these results underline the strong impact that the W163C ZAP-70 mutation has on T cell-driven arthritis, and they support the use of the SKG model in black mice, which is useful for further investigations of this distinctive arthritis model to better understand autoimmunity.

[An exceptional cause of pacemaker dysfunction]. / Une cause exceptionnelle de dysfonction de stimulateur cardiaque.

Twiddler syndrome is a very rare and surprising complication of pacemaker treatment. We report the case of a woman with psychiatric disease who presented two cardiac arrests due to loss of ventricular capture. Finally, pacemaker retropectoral implantation resolves the problem.

[Athlete's heart in the young: electrocardiographic and echocardiographic patterns in 107 French athletes]. / Le cœur d'athlète de l'adolescent : aspects électrocardiographiques et échocardiographiques. À propos de 107 sportifs français.

PURPOSE: Since 2009 in France, every people practicing sport in competition must have a cardiovascular exam with electrocardiogram, to prevent sudden cardiac death. Sometimes, an echocardiography will be necessary. Little is known about athlete's heart in the young, particularly in the French people. PATIENTS AND METHODS: One hundred and seven French elite adolescent athletes had an electrocardiogram with echocardiography to establish reference values in this population. RESULTS: QTcorrected (QTc) interval calculated by the Hodges formula, is always in the normal values. Interventricular septal thickness is always ≤ 11 mm and left ventricular end diastolic diameter ≤ 55 mm in about 90 % of the athletes. Females have QTc interval longer than males and interventricular septal thickness finer. Diastolic function (18.9 ± 2.6 cm/s for e', E/e' ratio at 5.3 ± 0.8) is "supernormal" and correlate with age and cardiac frequency. Right ventricular systolic function is always good. CONCLUSION: Adolescent athlete's heart is normal. If QTc interval is not normal, be afraid of a QT long syndrome. Furthermore, when interventricular septal thickness is > 11 mm or left ventricular end diastolic diameter > 55 mm, myocardiopathy will have to be ruled out.

Semi-automated stereoradiographic upper limb 3D reconstructions using a combined parametric and statistical model: a preliminary study.

PURPOSE: Quantitative assessment of 3D clinical indices may be crucial for elbow surgery planning. 3D parametric modeling from bi-planar radiographs was successfully proposed for spine and lower limb clinical investigation as an alternative for CT-scan. The aim of this study was to adapt this method to the upper limb with a preliminary validation. METHODS: CT-scan 3D models of humerus, radius and ulna were obtained from 20 cadaveric upper limbs and yielded parametric models made of geometric primitives. Primitives were defined by descriptor parameters (diameters, angles...) and correlations between these descriptors were found. Using these correlations, a semi-automated reconstruction method of humerus using bi-planar radiographs was achieved: a 3D personalized parametric model was built, from which clinical parameters were computed [orientation and projections on bone surface of trochlea sulcus to capitulum (CTS) axis, trochlea sulcus anterior offset and width of distal humeral epiphysis]. This method was evaluated by accuracy compared to CT-scan and reproducibility. RESULTS: Points-to-surface mean distance was 0.9 mm (2 RMS = 2.5 mm). For clinical parameters, mean differences were 0.4-1.9 mm and from 1.7° to 2.3°. All parameters except from angle formed by CTS axis and bi-epicondylar axis in transverse plane were reproducible. Reconstruction time was about 5 min. CONCLUSIONS: The presented method provides access to morphological upper limb parameters with very low level of radiation. Preliminary in vitro validation for humerus showed that it is fast and accurate enough to be used in clinical daily practice as an alternative to CT-scan for total elbow arthroplasty pre operative evaluation.

Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization.

When using skin markers and stereophotogrammetry for movement analysis, bone pose estimation may be performed using multi-body optimization with the intent of reducing the effect of soft tissue artefacts. When the joint of interest is the knee, improvement of this approach requires defining subject-specific relevant kinematic constraints. The aim of this work was to provide these constraints in the form of plausible values for the distances between origin and insertion of the main ligaments (ligament lengths), during loaded healthy knee flexion, taking into account the indeterminacies associated with landmark identification during anatomical calibration. Ligament attachment sites were identified through virtual palpation on digital bone templates. Attachments sites were estimated for six knee specimens by matching the femur and tibia templates to low-dose stereoradiography images. Movement data were obtained using stereophotogrammetry and pin markers. Relevant ligament lengths for the anterior and posterior cruciate, lateral collateral, and deep and superficial bundles of the medial collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect of landmark identification variability was evaluated performing a Monte Carlo simulation on the coordinates of the origin-insertion centroids. The ACL and LCL lengths were found to decrease, and the MCLdeep length to increase significantly during flexion, while variations in PCL and MCLsup length was concealed by the experimental indeterminacy. An analytical model is given that provides subject-specific plausible ligament length variations as functions of the knee flexion angle and that can be incorporated in a multi-body optimization procedure.

Monitoring trabecular bone microdamage using a dynamic acousto-elastic testing method.

Dynamic acousto-elastic testing (DAET) is based on the coupling of a low-frequency (LF) acoustic wave and high-frequency ultrasound (US) pulses (probing wave). It was developed to measure US viscoelastic and dissipative non-linearity in trabecular bone. It is well known that this complex biphasic medium contains microdamage, even when tissues are healthy. The purpose of the present study was to assess the sensitivity of DAET to monitor microdamage in human calcanei. Three protocols were therefore performed to investigate the regional heterogeneity of the calcaneus, the correlation between DAET measurements and microdamage revealed by histology, and DAET sensitivity to mechanically induced fatigue microdamage. The non-linear elastic parameter beta was computed for all these protocols. The study demonstrated the presence of high viscoelastic and dissipative non-linearity only in the region of the calcaneus close to the anterior talocalcaneal articulation (region of high bone density). Protocols 1 and 2 also showed that most unsorted calcanei did not naturally exhibit high non-linearity, which is correlated with a low level of microcracks. Nevertheless, when microdamage was actually present, high levels of US non-linearity were always found, with characteristic non-linear signatures such as hysteresis and tension/compression asymmetry. Finally, protocol 3 demonstrated the high sensitivity of DAET measurement to fatigue-induced microdamage.

[Heart failure and anaphylactic shock. A report of two cases]. / Défaillance cardiaque et choc anaphylactique. À propos de deux cas.

Anaphylactic shock can sometimes take the appearance of heart failure, in relation to an acute coronary syndrome, even with normal coronary arteries, that we illustrate by two observations. We firstly report the case of an anaphylactic shock caused by succinylcholine, after anesthesia induction for inguinal hernia surgery in a 50-year-old man with cardiovascular risks, who presented with ventricular fibrillation followed by a cardiac arrest. An acute and severe anterior coronary syndrome was suspected and treated with thrombolysis. Then the electrocardiogram normalized, as well as the left ventricular function. No significant coronary stenosis was retrospectively revealed by coronarography, and a severe coronary vasospasm induced by the anaphylactic reaction was confirmed. We also describe the case of an anaphylactoid shock caused by cisatracurium infusion, that occurred at the beginning of an adnexectomy in a 55-year-old woman without any particular history. She presented with a cardiogenic shock after intravenous administration of epinephrine. The echocardiograpghic evaluation pointed out an aspect of stress-induced cardiomyopathy, and the coronarography showed normal coronary arteries. The left ventricular dysfunction completely normalized, strongly suggesting the diagnosis of Takotsubo-like syndrome after the anaphylactic shock and its treatment. Both of these cases point out the major interest of cardiologic and allergic evaluation in case of heart failure during general anesthesia. Coronary vasospasm and stress-induced cardiomyopathy are two pathologies that may be observed during anaphylactic shock, and their diagnosis should be considered after elimination of coronary thrombosis.

Young's modulus repeatability assessment using cycling compression loading on cancellous bone.

For various applications, precision of the Young's modulus of cancellous bone specimens is needed. However, measurement variability is rarely given. The aim of this study was to assess the Young's modulus repeatability using a uniaxial cyclic compression protocol on embedded specimens of human cancellous bone. Twelve specimens from 12 human calcanei were considered. The specimens were first defatted and then 1 or 2 mm at the ends were embedded in an epoxy resin. The compression experiment consists in applying 20 compressive cycles between 0.2 per cent and 0.6 per cent strain with a 2 Hz loading frequency. The coefficient of variation of the current protocol was found to be 1.2 percent. This protocol showed variability similar to the end-cap technique (considered as a reference). It can be applied on porous specimen (especially human bone) and requires minimal bone length to limit end-artifact variability. The current method could be applied in association with noninvasive measurements (such as ultrasound) with full compatibility. This possibility opens the way for bone damage follow-up based on Young's modulus monitoring.

EOS orthopaedic imaging system to study patellofemoral kinematics: assessment of uncertainty.

BACKGROUND: Accurate knowledge of knee joint kinematics, especially patellofemoral joint kinematics,is essential for prosthetic evaluation so as to further improve total knee arthroplasty performances. Improving the evaluation of the functioning of the extensor apparatus appears,in this respect, particularly important in this optimization effort. OBJECTIVES: The aim of this study was to propose a new experimental setup for the analysis of knee joint kinematics and to validate its relevance in terms of accuracy and uncertainty.The technique developed herein combines 3D reconstruction imaging with the use of a motion capture system. MATERIAL AND METHODS: Eight pairs of fresh-frozen cadaver specimens with no evidence of previous knee surgery were studied using a new test rig where the femur remains fixed and the tibia is free to rotate. The flexion-extension cycles were executed using computer-controlled traction of the quadriceps tendon combined with an antagonist force applied to the distal part of the tibia. Knee joint kinematics were tracked using an optoelectronic motion capture system after a preliminary stage of data acquisition of bone geometry and markers position. This stage was carried out using a new digital stereophotogrammetric system, EOS, combined with specific 3D reconstruction software that also determined the coordinate system used in the kinematic analysis. The resulting uncertainty was assessed as was its impact on the estimated kinematics. RESULTS: Test results on eight knees validated the setup designed for the analysis of knee joint kinematics during the flexion-extension cycle. More specifically, the statistical results show that measurement uncertainty for rotations and translations remains below 0.4 and 1.8 mm,respectively, for the tibia and 0.4 and 1.2 mm for the patella (+/- 2 S.D. for all four measurements). DISCUSSION: The combination of 3D imaging and motion capture enables the proposed method to track the real-time motion of any bone segment during knee flexion-extension cycle. In particular,the new test rig introduced in this paper allows in vitro measurements of the patello femoral and tibiofemoral kinematics with a good level of accuracy. Moreover, this personalized experimental analysis can provide a more objective approach to the evaluation of knee implants as well as the validation of the finite-elements-based models of the patellofemoral joint.

[Normal values of the peak early diastolic Ea using myocardial tissue Doppler in 100 elite athletes]. / Valeur normale du pic protodiastolique Ea au doppler tissulaire myocardique chez les athlètes de haut niveau, à propos de cent sportifs.

INTRODUCTION: Intense physical training can induce morphological and functional changes in the heart, leading to 'Athlete's heart'. This can be responsible for adaptive left ventricular hypertrophy (LVH), which is sometimes difficult to differentiate from hypertrophic cardiomyopathy (HCM) with its inherent threat to life. Echocardiography usually allows the diagnosis to be clarified, but in borderline cases it can be insufficient. OBJECTIVE: The value of myocardial tissue Doppler (MTD) in the diagnosis of HCM has been highlighted recently. Normal values in athletes have been published, but these series have only studied a small number of athletes in a small number of sporting disciplines. METHODS: Using echocardiography with MTD at the lateral mitral annulus, we therefore evaluated 100 elite athletes from a very wide range of disciplines, in order to obtain a mean reference value for early diastolic Ea velocities. RESULTS: The peak early diastolic Ea was measured at 18.2 +/- 2.7 cm/s. The E/A ratio was 1.7 +/- 0.4. We found that 75% of the athletes had a value for Ea=17 cm/s, and for 84% of them the E/Ea ratio was correlated positively with the E/A ratio, and negatively with age. CONCLUSION: Elite athletes have early diastolic velocities measured with MTD that are higher due to their physical training. This study has allowed a mean reference value to be established for Ea in this specific population, with the potential opportunity to distinguish between LVH and HCM.

[Myocardial bridging and coronary spasm on effort]. / Pont myocardique et spasme coronaire à l'effort.

The discovery of myocardial bridging during coronary angiographies is common. Yet these bridges are rarely the origin of acute coronary syndrome. We report the case of an active 45 year old man with no cardiovascular risk factors who had acute coronary syndrome. Emergency coronary angiography just revealed two myocardial bridges on the anterior interventricular artery which did not explain this acute episode. A subsequent second angiogram together with endocoronary echography demonstrated that there was no atheroma and a methergin test set off diffuse coronary spasm. The association of myocardial bridging and coronary spasm has only rarely been reported in the literature. We describe the clinical, therapeutic and prognostic characteristics.

[Sudden death by coronary spasm: a particular and often unrecognised clinical entity]. / Mort subite par s pasme coronaire: une entité particulière, trop souvent méconnue.

The authors report 3 cases of resuscitated sudden death in which the investigations clearly showed coronary spasm. This was demonstrated by systematic coronary angiography with an ergometric test. Two patients underwent electrophysiological investigations which were normal. The three patients were prescribed long-term calcium antagonist therapy and one of them underwent coronary angioplasty. With a follow-up of 6 months to 3 years, there was no clinical recurrence or documented arrhythmia. A review of the literature shows that this is a cause of sudden death which is probably underestimated and unrecognised. Electrophysiological investigations often give disappointing results and medical therapy is the keystone of treatment. Coronary angioplasty and implantation of an automatic defibrillator are second-line treatments reserved to forms refractory to medical therapy.

[Unusual complication after hip surgery under spinal anesthesia]. / Complication inattendue après chirurgie de hanche sous rachianesthésie.

The development of an acute respiratory distress syndrome following hip surgery in elderly patients is suggestive of thromboembolism in most instances. However, we must keep in mind the possibility of rarer complications, which can remain undiagnosed because they are hidden by prominent abnormal behaviours, which can develop following any type of anaesthesia. We report the case of a patient who developed a confusion following an orthopaedic surgery under spinal anaesthesia; this confusion concealed a penetration syndrome resulting from accidental inhalation of a dental crown. Because this patient was old and had previously developed chronic lung disorders, we selected a spinal anaesthesia for performing the surgery; these underlying respiratory disorders worsened the clinical consequences of the inhalation. The dental crown was removed under general anaesthesia with spontaneous ventilation using a bronchoscope after an unsuccessful attempt with a fibrescope due to the size of the foreign body.

[Exertional hypertension and sport]. / Hypertension artérielle d'effort et sport.

Defining the normal range of blood pressure during exertion is not easy. Each type of exercise induces increased blood pressure that responds to a particular curve, and adaptation modes differ according to age, gender, physical condition, basal blood pressure, etc. The best studied is blood pressure measured on the arm using a cycloergometre. Classical publications established blood pressure curves according to heart rate during exercise. It appears that the best scale of reference for power developed occurs in individuals who can provide a very high degree of effort and in particular, athletes who are in very good training. According to some authors, hypertension on exertion would entail a poor prognosis, even in the absence of resting hypertension. Nevertheless, there is presently no well established therapeutic recommendation concerning exertion hypertension. This approach could depend on resting blood pressure and on the existence of other risk factors. For an athlete, pursuing physical activity is most often encouraged, sometimes after treatment or adjustment of its level.

[Spontaneous portal vein thrombosis associated with acute cytomegalovirus infection in an immunocompetent patient]. / Thrombose porte spontanée associée à une infection aiguë à cytomégalovirus chez une patiente immunocompétente.

BACKGROUND: Portal vein thrombosis (PVT) generally results from a local cause (hepatocellular and pancreatic carcinoma). Spontaneous PVT related to a general cause is less common. We report here a case of spontaneous PVT associated with acute cytomegalovirus (CMV) infection in an immunocompetent patient. CASE REPORT: A 31-year-old white female was admitted with fever and lymph node enlargement. The patient was a heavy smoker and was taking oral contraception. Blood tests revealed an inflammatory syndrome. Liver enzymes were elevated (2N) and platelet count was 118 G/l. Abdominal ultrasonography disclosed partial portal thrombosis. Computed tomography did not show any evidence of a hepatic or pancreatic mass. Protein S, protein C, and anti-thrombin III levels were normal. No antiphospholipid antibodies, no mutation for factors II and V and no abnormality suggestive of paroxysmal nocturnal hemoglobinuria at flow cytometry could be demonstrated. Acute CMV infection was diagnosis with positive viremia (PCR). The patient was given anticoagulation treatment and has done well with no relapse. CONCLUSION: Cytomegalovirus, by damaging endothelial cells, is thought to trigger a cascade of events leading to deep vein thrombosis. CMV infection does not appear to act alone on endothelial cells but rather behaves as an associated factor.

[A new case of pericardial thymic cyst]. / Un nouveau cas de kyste thymique paracardiaque.

The thymic cysts are benign tumours of the thymo-pharyngeal canal, usually located in the cervico-mediastinal region. The authors report the case of a large thymic cyst with an ectopic right paracardiac location compressing the right heart chambers. It was a chance finding on chest X-ray of an asymptomatic 21 year old man. Though suggestive of a pericardial cyst in view of its position, curative surgical ablation allowed confirmation of the diagnosis at anatomo-pathological examination.

[Myocardial infarction and anabolic steroid use. A case report]. / Infarctus du myocarde et prise d'anabolisants. A propos d'un cas.

The potential cardiotoxicity of anabolic steroids is not well known. The authors report the case of a young man who was a top class body builder and who developed severe ischaemic cardiomyopathy presenting with an inferior wall myocardial infarction. The clinical history revealed prolonged and intensive usage of two types of anabolic steroids to be the only risk factor. This cardiotoxicity may be related to several physiopathological mechanisms: accelerated atherogenesis by lipid changes, increased platelet aggregation, coronary spasm or a direct toxic effect on the myocytes. The apparent scarcity of the reported clinical details in the literature is probably an underestimation of the consequences of this usage.