Sclerosing mucoepidermoid carcinoma of the parotid gland

Although mucoepidermoid carcinoma is the most common primary malignancy of the salivary glands, the sclerosing morphologic variant of this tumor is extremely rare, with only 6 reported cases. As its name suggests, sclerosing mucoepidermoid carcinoma is characterized by an intense central sclerosis that occupies the entirety of an otherwise typical tumor, frequently with an inflammatory infiltrate of plasma cells, eosinophils, and/or lymphocytes at its peripheral regions. The sclerosis associated with these tumors may obscure their typical morphologic features and result in diagnostic difficulties. Tumor infarction and extravasation of mucin eventuating in reactive fibrosis are 2 mechanisms of formation that have been suggested as underlying this morphologic variant. We describe herein another case of sclerosing mucoepidermoid carcinoma that was diagnosed in a 44-year-old woman and review the relevant literature. Morphologic evidence in support of the mucin extravasation hypothesis was identified, as small pools of mucin were present throughout the tumor. However, there was no concentration of the mucin pools near the areas with the most viable tumor cells, which would have provided evidence for a temporal sequence that eventuates in lack of mucin in the most sclerotic regions.     

Inharmonicity detection

Detection of mistuned partials in otherwise harmonic complex tones was investigated in naïve subjects of three different age groups. Signals were presented at constant sensation level to compensate for differences in hearing sensitivity and to specifically examine age-related changes in inharmonicity perception. Performance was measured under two conditions, monaural signal presentation and dichotic signal-noise presentation, with the latter aiming at the influence of contralateral distractor sounds. Stimuli were complex tones with ten harmonics and 125-Hz fundamental frequency. Mistuning detection was measured for the first, second, fourth, and eighth harmonic. In a three-interval, three-alternative forced-choice procedure, subjects were required to distinguish a complex tone containing one mistuned partial from two reference tones, with all partials at their harmonic frequencies. Thresholds were measured as the amount of frequency shift necessary for the mistuning to be detected. Performance deteriorated moderately with age for the two higher partials tested, but not for the lower ones. Thresholds for dichotic signal/noise presentation did not differ significantly from monaural ones in any of the age groups. Results are discussed in relation to hypotheses of harmonicity perception in auditory scene analysis and with respect to the investigation of patients suffering form respective deficits due to acquired brain lesions.     

Differential stability and fusion activity of Lyssavirus glycoprotein trimers

The oligomeric structure and the fusion activity of lyssavirus glycoprotein (G) was studied by comparing G from Mokola virus (GMok) and rabies virus (PV strain) (GPV), which are highly divergent lyssaviruses. G expressed at the surface of BSR cells upon either plasmid transfection or virus infection are shown to be mainly trimeric after cross-linking experiments. However, solubilization by a detergent (CHAPS) and analysis in sucrose sedimentation gradient evidenced that GMok trimer is less stable than GPV trimer. A chimeric glycoprotein (G Mok-PV) associating the N-terminal half of GMok to the C-terminal half part of GPV formed trimers with an intermediate stability, indicating that the G C-terminal domain is essential in trimer stability. A cell to cell fusion assay revealed that GMok (and not G Mok-PV) was able to induce fusion at a higher pH (0.5 pH unit) than GPV. Such differences in the oligomeric structure stability and in the fusion activity of lyssavirus glycoproteins may partly account for the previously reported differences of their immunogenic and pathogenic properties.     

Syntactic comprehension in Parkinson's disease: investigating early automatic and late integrational processes using event-related brain potentials

Parkinson's disease (PD) has been associated with a general impairment of procedures and with an impairment of syntactic procedures in particular. The present study investigated comprehension processes in PD using event-related brain potentials (ERPs). PD patients and controls listened to sentences that were either correct or syntactically or semantically incorrect. The language-related ERP component correlated with semantic processes (N400) was present in both groups. In the syntactic domain, early automatic processes (early negativity) appeared normal in PD, whereas late integrational processes (P600) were modulated by this disease. The present findings suggest that the basal ganglia primarily do not support early automatic syntactic processes during comprehension but rather support processes of syntactic integration.     

Training to yoga respiration selectively increases respiratory sensation in healthy man

Because yoga practitioners think they are benefiting from their breath training we hypothesized that yoga respiration training (YRT) could modify the respiratory sensation. Yoga respiration (YR) ("ujjai") consisted of very slow, deep breaths (2-3 min(-1)) with sustained breath-hold after each inspiration and expiration. At inclusion in the study and after a 2-month YRT program, we determined in healthy subjects their eupneic ventilatory pattern and their capacity to discriminate external inspiratory resistive loads (respiratory sensation), digital tactile mechanical pressures (somesthetic sensation) and sound-pressure stimulations (auditory sensation). Data were compared to a gender-, age-, and weight-matched control group of healthy subjects who did not undergo the YRT program but were explored at the same epochs. After the 2-month YRT program, the respiratory sensation increased. Thus, both the exponent of the Steven's power law (Psi=kPhin) and the slope of the linear-linear plot between Psi and mouth pressure (Pm) were significantly higher, and the intercept with ordinate axis of the Psi versus Pm relationship was lower. After YRT, the peak Pm developed against inspiratory loads was significantly lower, reducing the load-induced activation of respiratory afferents. YRT induced long-lasting modifications of the ventilatory pattern with a significant lengthening of expiratory duration and a modest tidal volume increase. No significant changes in somesthetic and auditory sensations were noted. In the control group, the respiratory sensation was not modified during a 15-min period of yoga respiration, despite the peak Pm changes in response to added loads were then significantly reduced. These data suggest that training to yoga respiration selectively increases the respiratory sensation, perhaps through its persistent conditioning of the breathing pattern.     

Monte Carlo simulations of a scintillation camera using GATE: validation and application modelling

Geant4 application for tomographic emission (GATE) is a recently developed simulation platform based on Geant4, specifically designed for PET and SPECT studies. In this paper we present validation results of GATE based on the comparison of simulations against experimental data, acquired with a standard SPECT camera. The most important components of the scintillation camera were modelled. The photoelectric effect. Compton and Rayleigh scatter are included in the gamma transport process. Special attention was paid to the processes involved in the collimator: scatter, penetration and lead fluorescence. A LEHR and a MEGP collimator were modelled as closely as possible to their shape and dimensions. In the validation study, we compared the simulated and measured energy spectra of different isotopes: 99mTc, 22Na, 57Co and 67Ga. The sensitivity was evaluated by using sources at varying distances from the detector surface. Scatter component analysis was performed in different energy windows at different distances from the detector and for different attenuation geometries. Spatial resolution was evaluated using a 99mTc source at various distances. Overall results showed very good agreement between the acquisitions and the simulations. The clinical usefulness of GATE depends on its ability to use voxelized datasets. Therefore, a clinical extension was written so that digital patient data can be read in by the simulator as a source distribution or as an attenuating geometry. Following this validation we modelled two additional camera designs: the Beacon transmission device for attenuation correction and the Solstice scanner prototype with a rotating collimator. For the first setup a scatter analysis was performed and for the latter design. the simulated sensitivity results were compared against theoretical predictions. Both case studies demonstrated the flexibility and accuracy of GATE and exemplified its potential benefits in protocol optimization and in system design.     

Télomères monofonctionnels du chlorure de vinyle, 3. Cinétique par catalyse rédox

A kinetic study of the redox telomerization of vinyl chloride with carbon tetrachloride was carried out. Transfer constants of PVC to the metallic ion (C_Feⁿ), initiation rate (k_i), and functionnality of the resulting telomers were measured. Instantaneous and cumulated polymerization degrees, (DP_n )_i and (DP_n )_cum were determined with the help of a theoretical study. These constants provide a rigorous control of the telomerization of vinyl chloride with RCCl₃, (R containing an alcohol or ester group).     

Neurectodermal differentiation of extraskeletal myxoid chondrosarcoma: a classical feature?

Extraskeletal myxoid chondrosarcoma (EMC) is a phenotypically and genotypically distinct entity with a protracted course. A documented case of an extraskeletal myxoid chondrosarcoma characterized by a t(9; 17) (q22; q11) translocation with a neuroendocrine and neural differentiation is reported.