Peracute streptococcal pyomyositis: report of two cases and review of the literature

Pyomyositis occurs infrequently in temperate climates. The fulminating peracute form caused by group A Streptococcus is exceedingly rare. We present two children with streptococcal pyomyositis. One child was admitted in septic shock and required intensive supportive care during the acute stage of his illness. Persistent swelling and tenderness of his left thigh presented a diagnostic problem, which was eventually resolved with the aid of computerized tomography. Despite appropriate antibiotic therapy from the onset of illness, surgical debridement of the affected muscle was necessary. The second child presented with pyomyositis of the left paravertebral muscles and signs of incipient shock but did well on antibiotic therapy alone.     

Personal and family risk factors for adolescent suicidal ideation and attempts.

Despite research indicating that suicidal ideation is strongly related to future suicide attempts, there is limited data on variables associated with continued suicidal ideation and behaviors in adolescents. The objective of this study is to investigate whether personal, cognitive and family risk factors can differentiate adolescent suicidal ideation and attempts. Twenty-four attempters, 50 ideators and 50 non-suicidal adolescents (aged 14 to 25 years) were asked during an interview to complete individual and psychosocial measures. Both suicidal groups reported greater personal vulnerability and perceived their family as less functional than did the non-suicidal group. However, no differences were found between both suicidal groups. The results suggest the presence of common factors in both adolescent suicidal ideators and attempters.     

Dysferlin mutations in LGMD2B, Miyoshi myopathy, and atypical dysferlinopathies

DYSF encoding dysferlin is mutated in Miyoshi myopathy and Limb-Girdle Muscular Dystrophy type 2B, the two main phenotypes recognized in dysferlinopathies. Dysferlin deficiency in muscle is the most relevant feature for the diagnosis of dysferlinopathy and prompts the search for mutations in DYSF. DYSF, located on chromosome 2p13, contains 55 coding exons and spans 150 kb of genomic DNA. We performed a genomic analysis of the DYSF coding sequence in 34 unrelated patients from various ethnic origins. All patients showed an absence or drastic decrease of dysferlin expression in muscle. A primary screening of DYSF using SSCP or dHPLC of PCR products of each of 55 exons of the gene was followed by sequencing whenever a sequence variation was detected. All together, 54 sequence variations were identified in DYSF, 50 of which predicting either a truncated protein or one amino-acid substitution and most of them (34 out of 54) being novel. In 23 patients, we identified two pathogenic mutations, while only one was identified in 11 patients. These mutations were widely spread in the coding sequence of the gene without any mutational "hotspot."     

Prenatal detection of a 17p11.2 duplication resulting from a rare recombination event and novel PCR-based strategy for molecular identification of Charcot-Marie-Tooth disease type 1A

Charcot-Marie-Tooth disease, type 1A (CMT1A) is caused in most cases by a 1.5 Mb duplication on chromosome 17p11.2 arising after unequal crossing-over between repeated sequences called CMT1A-REPs, flanking the 1.5 Mb unit. A 3.2 kb recombination hot spot has been defined, resulting in a junction fragment between EcoRI (distal CMT1A-REP) and SacI (proximal CMT1A-REP). This was further reduced to a 1.7kb EcoRI-NsiI fragment, and recently to a 731 bp hot spot region within this fragment. We describe the CMT1A-REPs-based PCR method used to identify CMT1A duplications and report on a family case in which a 29-year-old pregnant woman requested prenatal diagnosis for two successive pregnancies because her husband was affected with CMT1A. Our method enabled us to characterise the duplication in both foetuses and demonstrate that it arose from a rare recombination event taking place outside the 1.7 kb region. Since our approach is simple and enables the entire set of duplications occurring after recombination in the enlarged 3.2kb region including the hot spot to be detected, we suggest it might be considered for use in primary screening for pre- and postnatal diagnosis of CMT1A.     

Patient-specific mechanical properties of a flexible multi-body model of the scoliotic spine

The flexibility of the scoliotic spine is an important biomechanical parameter to take into account in the planning of surgical instrumentation. The objective of the paper was to develop a method to characterisein vivo the mechanical properties of the scoliotic spine using a flexible multi-body model. Vertebrae were represented as rigid bodies, and intervertebral elements were defined at every level using a spherical joint and three torsion springs. The initial mechanical properties of motion segments were defined fromin vitro experimental data reported in the literature. They were adjusted using an optimisation algorithm to reduce the discrepancy between the simulated and the measured Ferguson angles in lateral bending of three spine segments (major or compensatory left thoracic, right thoracic and left lumbar scoliosis curves). The flexural rigidity of the spine segments was defined in three categories (flexible, nominal, rigid) according to the estimated mechanical factors (α). This approach was applied with ten scoliotic patients under-going spinal correction. Personalisation of the model resulted in an increase of the initial flexural rigidity for seven of the ten lumbar segments (1.38≤α≤10.0) and four of the ten right thoracic segments (1.74≤α≤5.18). The adjustment of the mechanical parameters based on the lateral bending tests improved the model's ability to predict the spine shape change described by the Ferguson angles by up to 50%. The largest differences after personalisation were for the left lumbar segments in left bending (4⁰±3⁰). Thein vivo identification of the mechanical properties of the scoliotic spine will improve the ability of biomechanical models adequately to predict the surgical correction, which should help clinicians in the planning of surgical instrumentation manoeuvres.     

Comparison between clinical Cobb angles and measurements performed on vertebral bodies, pedicle centroids and spinous processes

GOAL: Evaluate the relations between the clinical Cobb angle measured on radiographic images and the computerized Cobb angles measured on curves passing through: 1) the vertebral body centroids, 2) the pedicle centroids and 3) the spinous process tips, in the frontal plane, the sagittal plane and the plane of maximum curvature. MATERIAL AND METHODS: A bi-planar radiographic technique was used to reconstruct in 3D the spine geometry for 39 adolescent girls having double-curved idiopathic scoliosis. The Cobb angles were measured clinically on the radiographs and were computed on the 3 curves. RESULTS: Every relation was found significant and their determination coefficient (R2) was between 0.38 and 0.98. Linear relations were established between clinical and computerized angles. Angles measured on the curve passing through the pedicle centroid correlated best with clinical indices. CONCLUSIONS: The computerized measurements of Cobb angles from 3D models can be used with confidence and are interchangeable, provided the appropriate conversion factor is used.     

Exogenous BDNF, NT-3 and NT-4 differentially regulate neurite outgrowth in cultured hippocampal neurons

Multiple growth factors contribute to the differentiation of dendritic and axonal processes by a neuron. Cultured hippocampal cells elaborate dendritic and axonal processes following well-defined steps. We used this culture system to determine the specific effects of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) on dendritic and axonal differentiation in hippocampal pyramidal neurons. We demonstrated that each of these neurotrophins exert distinct effects on neurite outgrowth. Both BDNF and NT-3 had positive effects on the outgrowth of undifferentiated neurites, called minor neurites, and on the axonal process of hippocampal pyramidal neurons. However, the effect of NT-3 was more important than that of BDNF. On the other hand, NT-4 did not enhance axonal outgrowth but had only an effect on the outgrowth of minor neurites. Since cytoskeletal proteins play crucial roles in promoting neurite outgrowth, we examined the protein levels of some of these proteins that are associated with neurite outgrowth: beta-actin, gamma-actin, alpha-tubulin, MAP2 and tau. Surprisingly, we did not detect any change in their protein levels. Taken together, our results show that BDNF, NT-3 and NT-4 exert distinct effects on the neuritic compartments of hippocampal neurons.     

Artificial neural networks assessing adolescent idiopathic scoliosis: comparison with Lenke classification

Background contextVariability in classifying and selecting levels of fusion in adolescent idiopathic scoliosis (AIS) has been repeatedly documented. Several computer algorithms have been used to classify AIS based on the geometrical features, but none have attempted to analyze its treatment patterns.PurposeTo use self-organizing maps (SOM), a kind of artificial neural networks, to reliably classify AIS cases from a large database. To analyze surgeon's treatment pattern in selecting curve regions to fuse in AIS using Lenke classification and SOM.Study designThis is a technical concept article on the possibility and benefits of using neural networks to classify AIS and a retrospective analysis of AIS curve regions selected for fusion.Patient sampleA total of 1,776 patients surgically treated for AIS were prospectively enrolled in a multicentric database. Cobb angles were measured on AIS patient spine radiographies, and patients were classified according to Lenke classification.Outcome measuresFor each patient in the database, surgical approach and levels of fusion selected by the treating surgeon were recorded.MethodsA Kohonen SOM was generated using 1,776 surgically treated AIS cases. The quality of the SOM was tested using topological error. Percentages of prediction of fusion based on Lenke classification for each patient in the database and for each node in the SOM were calculated. Lenke curve types, treatment pattern, and kappa statistics for agreement between fusion realized and fusion recommended by Lenke classification were plotted on each node of the map.ResultsThe topographic error for the SOM generated was 0.02, which demonstrates high accuracy. The SOM differentiates clear clusters of curve type nodes on the map. The SOM also shows epicenters for main thoracic, double thoracic, and thoracolumbar/lumbar curve types and transition zones between clusters. When cases are taken individually, Lenke classification predicted curve regions fused by the surgeon in 46% of cases. When those cases are reorganized by the SOM into nodes, Lenke classification predicted the curve regions to fuse in 82% of the nodes. Agreement with Lenke classification principles was high in epicenters for curve types 1, 2, and 5, moderate in cluster for curve types 3, 4, and 6, and low in transition zones between curve types.ConclusionsAn AIS SOM with high accuracy was successfully generated. Lenke classification principles are followed in 46% of the cases but in 82% of the nodes on the SOM. The SOM highlights the tendency of surgeons to follow Lenke classification principles for similar curves on the SOM. Self-organizing map classification of AIS could be valuable to surgeons because it bypasses the limitations imposed by rigid classification such as cutoff values on Cobb angle to define curve types. It can extract similar cases from large databases to analyze and guide treatment.