Pediatric seatbelt injuries: unusual Chance's fracture associated with intra-abdominal lesions in a child

The authors report the case of a 7-year-old child involved in a motor vehicle accident. She sustained an unusual flexion-distraction vertebral injury. This spinal injury was related to seatbelt use and was associated with intra-abdominal lesions. The spinal lesion consisted of a posterior ligamentous disruption with widening of the posterior intervertebral space at two adjacent lumbar levels. The purpose of this case report is to describe an atypical and perhaps often unrecognized spinal lesion and to explain our approach to diagnosis and treatmen

Enamel crystals of mice susceptible or resistant to dental fluorosis: an AFM study

Objective: This study aimed to assess the overall apatite crystals profile in the enamel matrix of mice susceptible (A/J strain) or resistant (129P3/J strain) to dental fluorosis through analyses by atomic force microscopy (AFM). Material and Methods: Samples from the enamel matrix in the early stages of secretion and maturation were obtained from the incisors of mice from both strains. All detectable traces of matrix protein were removed from the samples by a sequential extraction procedure. The purified crystals (n=13 per strain) were analyzed qualitatively in the AFM. Surface roughness profile (Ra) was measured. Results: The mean (±SD) Ra of the crystals of A/J strain (0.58±0.15 nm) was lower than the one found for the 129P3/J strain (0.66±0.21 nm) but the difference did not reach statistical significance (t=1.187, p=0.247). Crystals of the 129P3/J strain (70.42±6.79 nm) were found to be significantly narrower (t=4.013, p=0.0013) than the same parameter measured for the A/J strain (90.42±15.86 nm). Conclusion: enamel crystals of the 129P3/J strain are narrower, which is indicative of slower crystal growth and could interfere in the occurrence of dental fluorosis

Gait in adolescent idiopathic scoliosis: energy cost analysis

Walking is a very common activity for the human body. It is so common that the musculoskeletal and cardiovascular systems are optimized to have the minimum energetic cost at 4 km/h (spontaneous speed). A previous study showed that lumbar and thoracolumbar adolescent idiopathic scoliosis (AIS) patients exhibit a reduction of shoulder, pelvic, and hip frontal mobility during gait. A longer contraction duration of the spinal and pelvic muscles was also noted. The energetic cost (C) of walking is normally linked to the actual mechanical work muscles have to perform. This total mechanical work (Wtot) can be divided in two parts: the work needed to move the shoulders and lower limbs relative to the center of mass of the body (COMb) is known as the internal work (Wint), whereas additional work, known as external work (Wext), is needed to accelerate and lift up the COMb relative to the ground. Normally, the COMb goes up and down by 3 cm with every step. Pathological walking usually leads to an increase in Wtot (often because of increased vertical displacement of the COMb), and consequently, it increases the energetic cost. The goal of this study is to investigate the effects of scoliosis and scoliosis severity on the mechanical work and energetic cost of walking. Fifty-four female subjects aged 12 to 17 were used in this study. Thirteen healthy girls were in the control group, 12 were in scoliosis group 1 (Cobb angle [Cb] ≤ 20°), 13 were in scoliosis group 2 (20° < Cb < 40°), and 16 were in scoliosis group 3 (Cb ≥ 40°). They were assessed by physical examination and gait analysis. The 41 scoliotic patients had an untreated progressive left thoracolumbar or lumbar AIS. During gait analysis, the subject was asked to walk on a treadmill at 4 km h−1. Movements of the limbs were followed by six infrared cameras, which tracked markers fixed on the body. Wint was calculated from the kinematics. The movements of the COMb were derived from the ground reaction forces, and Wext was calculated from the force signal. Wtot was equal to Wint + Wext. Oxygen consumption \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {\dot{V}{\text{O}}_{2} } \right)$$\end{document} was measured with a mask to calculate energetic cost (C) and muscular efficiency (Wtot/C). Statistical comparisons between the groups were performed using an analysis of variance (ANOVA). The external work (Wext) and internal work (Wint) were both reduced from 7 to 22% as a function of the severity of the scoliosis curve. Overall, the total muscular mechanical work (Wtot) was reduced from 7% to 13% in the scoliosis patients. Within scoliosis groups, the Wext for the group 1 (Cb ≥ 20°) and 2 (20 ≤ Cb ≤ 40°) was significantly different from group 3 (Cb ≥ 40°). No significant differences were observed between scoliosis groups for the Wint. The Wtot did not showed any significant difference between scoliosis groups except between group 1 and 3. The energy cost and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document} were increased by around 30%. As a result Muscle efficiency was significantly decreased by 23% to 32%, but no significant differences related to the severity of the scoliosis were noted. This study shows that scoliosis patients have inefficient muscles during walking. Muscle efficiency was so severely decreased that it could be used as a diagnostic tool, since every scoliosis patient had an average muscle efficiency below 27%, whereas every control had an average muscle efficiency above 27%. The reduction of mechanical work found in scoliotic patients has never been observed in any pathological gait, but it is interpreted as a long term adaptation to economize energy and face poor muscle efficiency. With a relatively stiff gait, scoliosis patients also limit vertical movement of the COMb (smoothing the gait) and consequently, reduce Wext and Wint. Inefficiency of scoliosis muscles was obvious even in mild scoliosis (group 1, Cb < 20°) and could be related to the prolonged muscle contraction time observed in a previous study (muscle co-contraction)

Transfert des polluants nucléaires et conventionnels en rizière irriguée

Les rizières irriguées par submersion constituent, en raison des quantités énormes d’eau utilisées, des écosystèmes particulièrement importants à envisager dans le cadre des recherches sur les conséquences de rejets d’effluents liquides, industriels ou radioactifs, dans les eaux continentales. On a recouru à des modèles réduits de rizières artificielles, simulant les conditions naturelles de la riziculture en Italie du Nord. On a suivi le comportement de radionucléides de fission ou d’activation, en particulier celui de 137Cs, 60Co, 65Zn, 51Cr, et celui de polluants métalliques particulièrement dangereux (Cd, Cr, Sn). Les phénomènes de transfert et de concentration dans les sols et les divers organes du riz ont été évalués quantitativement et leurs incidences, notamment en ce qui concerne les apports alimentaires à l’homme, discutées

Very Short-Term Effect of Brace Wearing on Gait in Adolescent Idiopathic Scoliosis Girls

PURPOSE: Adolescent idiopathic scoliotic (AIS) deformity induces excessive oxygen consumption correlated to a bilateral increase of lumbo-pelvic muscles timing activity (EMG) during gait. Wearing a brace, the usual treatment for AIS, by supporting the spine and the pelvis, would generate lumbo-pelvic muscular relaxation and consequently reduce excessive oxygen consumption. The purpose of this study was to evaluate the short-term effect of bracing on gait biomechanics in scoliotic spine when compared with normal braced spine. METHODS: Thirteen healthy volunteers were compared to 13 AIS girls. In both samples, gait analysis was assessed using a three-dimensional motion analysis, including synchronous kinematic, electromyographic, mechanical and energy measurements, first without brace, then wearing a brace. RESULTS: For scoliotic patients, comparison of in-brace and out-brace situations revealed a significant decrease of frontal pelvis (p < 0.001), hip (p < 0.001) and shoulder (p = 0.004) motion in brace associated with a significant reduction of pelvis rotation (p = 0.003). However, the brace did not change significantly the lumbo-pelvic muscle activity duration (EMG) or the mechanical and energetic parameters. Transversal pelvis motion was reduced by 39 % (p = 0.04), frontal hip and shoulder motions by 23 % (p = 0.004) and 30 % (p = 0.01) respectively, and energy cost of walking remained increased by 37 % in braced AIS girls relatively to braced healthy subjects. Mechanical and electromyographic variables were not significantly different between the two braced populations during gait except for the gluteus medius muscle that showed bilaterally an increase of duration of electrical activity in healthy subjects and contrarily a decrease in AIS patients (healthy: −3.5 ± 9.6 % of gait cycle vs. scoliotic: 3.7 ± 7.7 % of gait cycle; p = 0.04). CONCLUSIONS: Bracing changed neither the oxygen consumption nor the timing of the lumbo-pelvic muscles activity in both groups during gait. However, in brace the timing activity of bilateral gluteus medius muscles tended to decrease in AIS patients and increase in healthy subjects. Moreover, braced AIS patients had more restricted frontal hips and shoulder motion as well as pelvis rotation than braced healthy subjects