Thermo-Hydro-Glycol Ageing of Polyamide 6,6: Microstructure-Properties Relationships.

The microstructural evolutions occurring during the thermo-hydro-glycol ageing of an injection molded PA66 were studied. They were correlated to the evolutions of its mechanical properties. The aged samples were immersed in an antifreeze fluid-mainly composed of water and ethylene glycol-at varying times and temperatures. The aim was to combine an as exhaustive as possible microstructural investigation and a rigorous mechanical analysis. Consequently, the microstructure of the aged and unaged PA66 was assessed through the average molar mass, the diameter of the spherulites, the lamellae thickness, the crystallite's apparent size, a crystal perfection index, and a crystallinity index. Moreover, a core-skin approach was set up. The mechanical consequences of the microstructural changes were investigated by DMA and tensile testing. The local true strain fields were measured with a digital image correlation system. The temperatures and strain rates of the tests were chosen by referring to the time-temperature superposition principle. It is concluded that the water and ethylene glycol intake resulted in an intense plasticization, the loss of the molar mass resulted in the embrittling of the polymer, and finally, it was identified that the changes of the crystalline structure have an influence on the stiffness of PA66.

Microsurgical Transcranial Approach of 112 Paraoptic Meningiomas: A Single-Center Case Series.

BACKGROUND: Predictors of visual outcomes after optic nerve decompression are controversial. OBJECTIVE: To identify the predictors of poor visual outcomes after surgery of meningiomas responsible of a compressive optic neuropathy. METHODS: We focused on paraoptic meningiomas (POMs), which gathered tuberculum sellae meningiomas (TSMs) and anterior clinoid meningiomas (ACMs) responsible for visual impairment or threatening visual function, that underwent surgery at our institution between January 2009 and December 2015 and analyzed the clinical and radiological findings of our patients. RESULTS: Among 112 patients who underwent surgery for a POM, a preoperative visual deficit was present in 108 patients (96.4%). Six months after surgery, 79 patients (70.5%) had a visual improvement, 15 patients (13.4%) had an unchanged vision, and 18 patients (16.1%) had deteriorated vision. A preoperative visual deficit of 6 mo or more was a strong predictor of poor visual outcome after surgery (P = .034). Poor visual outcome after surgery was not significantly related to the size of the tumor (P = .057), the age of the patient (P = .94), or the tumor extension into the optic canal (P = .47). CONCLUSION: The duration of preoperative visual deficit was found to be a strong predictor of poor visual outcomes after surgery in POMs Other predictors of poor visual outcomes are still needed and are currently under evaluation in a prospective study at our institution.

Mechanical Behavior-Microstructure Relationships in Injection-Molded Polyamide 66.

Clear relationships between the semi-crystalline microstructure of injection molding polymers and their mechanical behavior are not yet totally established for all polymers. Part of this relative lack of understanding is because an unambiguous scientific approach is difficult to build up. The processing of samples promotes a microstructure which is not uniform and can be described in various ways on different scales. This introduces uncertainty in the correlations. Most completed studies were conducted on polyolefin, which exhibits an evolution of microstructure that is quite easy to observe and to correlate to mechanical properties. This paper intends to illustrate a more diffuse case. To achieve this, combined characterizations along the flow path and throughout the thickness of a plaque as well as characterizations of the local microstructure and tensile behavior of polyamide 66 are described. The microstructure was explored in terms of skin-core structure, spherulites sizes, crystallinity ratio and lamellae organization. Mechanical properties were addressed with non-monotonic tests with the use of DIC (Digital Image Correlation) to assess true behavior. The effect of humidity is also accounted for. It is demonstrated that small changes in lamellae or interlamellar amorphous phase are likely to be responsible for non-uniform mechanical properties, whereas more macroscopic levels (skin core structure, spherulites level of crystallinity ratio) appeared to be irrelevant levels of description. Consequently, the usual simplified analyses based on optical microscopy and differential scanning calorimetry (DSC) can be inefficient in improving knowledge in that field.

[A case report of chordoid glioma with unusual features: Immunohistochemical and molecular findings and differential diagnoses]. / Un cas de gliome chordoïde inhabituel : aspects immunohistochimiques et moléculaires et diagnostics différentiels.

We report the case of a 63-year-old healthy patient who was admitted for surgery of a suprasellar tumor with extension to the optic chiasm responsible of visual disturbance. Histopathological examination revealed a tumoral proliferation composed of epithelioid cells without atypia arranged in cords in a mucinous matrix surrounded by some lymphocytic inflammatory infiltrates. On immunohistochemistry, the neoplastic cells strongly expressed GFAP and CD34, a weak expression of EMA, an expression of TTF1 without immunoreactivity for brachyury. Ki-67 labeling index was low around 1%. The diagnosis of chordoid glioma was made. Surprisingly, tumor cells expressed IDH1R132H but molecular analysis did not reveal any mutation of IDH1/2 genes. There was no expression of p53 but high overexpression of EGFR. Chordoid glioma is a rare and low-grade entity. The precise histogenesis remains debated. Our case is unusual because of the infiltration of the optic chiasm and because of the immunoexpression of IDH1R132H without underlying mutations of IDH1/2 genes.

The prevalence of IgG4-positive plasma cells in hypophysitis: a possible relationship to IgG4-related disease.

AIMS: Hypophysitis is a rare chronic inflammation of the pituitary gland corresponding currently to six histopathological subtypes. Among them, immunoglobulin- G4-related hypophysitis was recently added in this classification. The aim of this study was to perform a retrospective histopathological and immunohistochemical analysis to evaluate the prevalence of IgG4-related hypophysitis and review reported cases. METHODS: All samples of hypophysitis from Lariboisiere hospital were reviewed by two pathologists to assess their subtypes. An immunohistochemistry against IgG4 and IgG was performed. Slides were numerized, and IgG4-positive plasma cells and IgG plasma cells were counted in three high-power fields to evaluate the ratio. RESULTS: Eight cases were included: 5 lymphocytic hypophysitis, 1 granulomatous subtype, and 2 IgG4-related hypophysitis, affecting two young women without other coaffected organ. CONCLUSION: Our results show that IgG4-related hypophysitis is not an exceptional entity. Storiform fibrosis and obliterative phlebitis, histopathological characteristics of IgG4-related disease in other organs, are lacking in pituitary lesions. This study proves the interest of immunohistochemistry for diagnosis of IgG4-related hypophysitis. Due to the sensibility of IgG4-disease to steroids in other organs, this finding could be of clinical relevance.

Measured wavenumber: frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations.

Direct measurements of the wavenumber-frequency spectrum of wall pressure fluctuations beneath a turbulent plane channel flow have been performed in an anechoic wind tunnel. A rotative array has been designed that allows the measurement of a complete map, 63×63 measuring points, of cross-power spectral densities over a large area. An original post-processing has been developed to separate the acoustic and the aerodynamic exciting loadings by transforming space-frequency data into wavenumber-frequency spectra. The acoustic part has also been estimated from a simple Corcos-like model including the contribution of a diffuse sound field. The measured acoustic contribution to the surface pressure fluctuations is 5% of the measured aerodynamic surface pressure fluctuations for a velocity and boundary layer thickness relevant for automotive interior noise applications. This shows that for aerodynamically induced car interior noise, both contributions to the surface pressure fluctuations on car windows have to be taken into account.

[Gliomatosis cerebri: a biopsy and autopsy case report]. / Gliomatose cérébrale diffuse: étude biopsique et autopsique d'un cas.

Gliomatosis cerebri is a rare glial neoplasm, characterized by diffuse brain infiltration with relative preservation of the underlying cytoarchitecture. Its clinical and radiologic features are not specific and its antemortem diagnosis is difficult. We report a case of gliomatosis cerebri in a 68-year-old woman presenting with gait disturbances and episodic seizures. MRI showed bilateral white matter hypersignal intensities on Flair sequences and brain biopsy revealed a poorly cellular proliferation of neoplasic glial cells strongly expressing OLIG-2, Ki-67 and occasionally GFAP, without alpha-internexin expression. The patient status worsened rapidly and she died 2 months after the initial symptoms. Postmortem brain examination confirmed gliomatosis cerebri and revealed a focal glioblastoma in the frontal cortex, with nuclear p53 expression in the highest malignant areas. Gliomatosis cerebri should be included in the differential diagnostic of diffuse brain lesions. Antemortem diagnosis, although difficult, can be assessed by IRM and careful biopsy examination. Progression to glioblastoma has been seldom reported, enhancing the controversy about the etiopathogenesis of this rare tumour.

Long-term results with exophthalmos in a surgical series of 30 sphenoorbital meningiomas. Clinical article.

OBJECT: The authors analyzed the long-term results and radiological aspects of sphenoorbital meningioma (with emphasis on exophthalmos) in a series of 30 patients who underwent resection. METHODS: Data obtained in all 30 patients who underwent surgery for typical sphenoorbital meningioma at the authors' institution between June 1994 and September 2005 were analyzed retrospectively. The exophthalmos index (EI) was measured on preoperative MR images and/or CT scans and compared between the early and last follow-up examinations. All patients were women 35-74 years of age (median 51 years). Exophthalmos was the presenting symptom in 28 patients (93%), and was observed on preoperative MR images in all patients. The median duration of symptoms before surgery was 10 months (2-120 months). RESULTS: Total resection (Simpson Grade I) was not achieved in these patients because of the impossibility of resecting the dura mater in the superior orbital fissure without causing significant complications. Subtotal resection (Simpson Grade II) was obtained in 90% of patients, and in 3 patients (10%) a portion of the tumor was deliberately left in place because of extensive macroscopic infiltration of the cavernous sinus and/or extraocular muscles (Simpson Grade III). No patient died. Radiological evaluation at a median follow-up of 61 months (range 17-136 months) showed no contrast enhancement in 14 patients (47%), residual contrast enhancement without evolution in 13 (43%), and recurrence (new contrast enhancement) in 3 (10%). The EI was improved at the first radiological follow-up (median 12 months) in 27 patients (90%), and at the last radiological follow-up (median 61 months) in 28 patients (93%). In the interval between the first and final imaging follow-up, the EI improved in only 8 patients (20%), worsened in 15 patients (50%), and showed no variation in 7 patients (30%). CONCLUSIONS: Sphenoorbital meningiomas are insidious tumors with slow progression. Even when exophthalmos is not clinically evident, it is always present on preoperative MR imaging. Total resection is not possible due to superior orbital fissure invasion, but subtotal resection (Simpson Grade II) can assure long-term stability due to the nonevolutive nature of most residual tumors. Exophthalmos improves at early radiological follow-up, but may worsen again as time passes.

Coordination between postural and movement controls: effect of changes in body mass distribution on postural and focal component characteristics.

Whole-body reaching movements are accomplished through a combination of anticipatory postural adjustments (APAs) and focal movements. Two different modes of central organization is usually proposed for this coordination: first, a single-process control, where the APAs and the focal movements would share a common command; second, where the APAs and the focal movements would be independently controlled through parallel commands (dual-process control). Here, we investigated which one of these modes of control could better explain the coordination between the trunk and the upper limb for standing subjects reaching for a target located beyond arm's length. This was done evaluating the effect of changing the APAs settings on the arm movement. The APAs modification was achieved by shifting the subject's centre of mass prior to the focal movement onset; this was done by adding an asymmetric load on either side of the head (a control condition with the load fixed centrally at the top of the head was also performed). As it changed the body mass distribution, the muscular torques and the orientation of the head inertia tensor, it is assumed that the addition of the asymmetric load led to a change in the APAs. Analyses indeed showed that both the initial head and trunk displacement towards the supporting side (during the unloading of the moving leg) were smaller when the load was fixed on the side of the supporting leg than when it was fixed on the side of the moving leg. However, changing the initial conditions, and therefore the APAs settings, had no significant effect on the path and kinematics of the focal hand movement. Therefore, subjects cancelled out the effect of the trunk motion on the hand-in-space motion through compensatory arm movements. These results support the dual-process control hypothesis for the postural and the focal components.

Inter-segmental coordination: motor pattern in humans stepping over an obstacle with mechanical ankle joint friction.

This study examined the influence of a mechanical perturbation of the ankle joint on obstacle avoidance pattern. A decoupled control between the distal joint and the combined (hip-knee) proximal joints was observed according to the task requirement. In this context, a greater mechanical friction at the ankle should be compensated at this joint (local compensation) or alternatively, by regulating more combined proximal joints (knee and/or hip). The leading limb inter-segmental coordination was evaluated in both no constraint and constraint conditions in calculating ranges of motion (ROM), moments of force and powers (from heel-off to obstacle) at the ankle, knee and hip joints. Electromyographic activities were also analyzed. With the constraint, the dorsiflexor moment and the tibialis anterior activity remained unchanged while both ROM and power bursts (absorbed and generated) decreased. The hip and knee ROM remain invariant. At heel-off the absorption by hip extensors decreased and the forthcoming generation by knee flexors increased in the constraint condition. To quantify the inter-joint coordination, principal component analysis was used and indicated a high level of inter-joint coupling (synergy) that decreased with the constraint (i.e. less inter-joint coupling). At the ankle joint, the results suggest that the central command was the same in both conditions thus, not be adapted. At both the hip and knee joints, a combined joints modulation occurred to overcome additional friction.

Case report: human brain abscess due to a tetra-acetabulate plerocercoid metacestode (Cyclophyllidea).

A 38-year-old man living near Phnom Penh (Cambodia) was admitted to a hospital in Paris in June 2001 for a single episode of a generalized grand mal seizure. This episode was preceded by a 9-month history of headaches. Magnetic resonance imaging (MRI) of the head revealed a rounded lesion immediately ahead of the left central sulcus. The resected lesion was about 20 mm in diameter. Histologic examination revealed an elongated but unsegmented metacestode at the center of the lesion. Polymerase chain reaction (PCR) analysis was inconclusive due to formalin-based histologic processing of the tissue. Morphologic analysis based on the histologic sections revealed that the metacestode was a tetra-acetabulate plerocercoid of the order Cyclophyllidea, with a distinct rostellum and pseudosegmentation of the dorsoventrally flattened hindbody. This is the first report of a tetra-acetabulate plerocercoid from a human host and the first report of any cyclophyllidean plerocercoid from the human brain. After 6 weeks, the patient was asymptomatic, neurologic examination was normal, and the brain MRI showed only surgical cavitation. The patient returned to Cambodia.