Neuromyelitis optica does not impact periventricular venous density versus healthy controls: a 7.0 Tesla MRI clinical study

Objective

To quantify the periventricular venous density in neuromyelitis optica spectrum disease (NMOSD) in comparison to that in patients with multiple sclerosis (MS) and healthy control subjects.

Materials and methods

Sixteen patients with NMOSD, 16 patients with MS and 16 healthy control subjects underwent 7.0-Tesla (7T) MRI. The imaging protocol included T₂*-weighted (T₂*w) fast low angle-shot (FLASH) and fluid-attenuated inversion recovery (FLAIR) sequences. The periventricular venous area (PVA) was manually determined by a blinded investigator in order to estimate the periventricular venous density in a region of interest-based approach.

Results

No significant differences in periventricular venous density indicated by PVA were detectable in NMOSD versus healthy controls (p = 0.226). In contrast, PVA was significantly reduced in MS patients compared to healthy controls (p = 0.013).

Conclusion

Unlike patients with MS, those suffering from NMOSD did not show reduced venous visibility. This finding may underscore primary and secondary pathophysiological differences between these two distinct diseases of the central nervous system.

     

Low‐power quadrature generators for body area network applications

This paper presents different alternatives for the implementation of low‐power monolithic oscillators for wireless body area networks and describes the design of two quadrature generators operating in the 2.4‐GHz frequency range. Both implementations have been designed in a 90‐nm Complementary Metal‐Oxide Semiconductor (CMOS) technology and operate at 1 V of supply voltage. The first architecture uses a voltage‐controlled oscillator (VCO) running at twice the desired output frequency followed by a divider‐by‐2 circuit. It experimentally consumes 335 μW and achieves a phase noise of ?110.2 dBc/Hz at 1 MHz. The second architecture is a quadrature VCO that uses reinforced concrete phase shifters in the coupling path for phase noise improvement. Its power consumption is only 210 μW, and it obtains a phase noise of ?111.9 dBc/Hz at 1 MHz. Copyright © 2011 John Wiley & Sons, Ltd.     

PET/MR for therapy response evaluation in malignant lymphoma: initial experience

Object

To evaluate the feasibility of positron emission tomography/magnetic resonance imaging (PET/MR) with ¹⁸fluoro-2-deoxyglucose (FDG) for therapy response evaluation of malignant lymphoma.

Materials and methods

Nine patients with malignant lymphoma who underwent FDG-PET/MR before and after chemotherapy were included in this retrospective study. Average time between the two scans was 70 days. The scans were evaluated independently by two nuclear medicine physicians. The Ann Arbor classification was used to describe lymphoma stage. Furthermore, the readers also rated PET image quality using a five point scale. Weighted kappa (κ) was used to calculate interrater agreement.

Results

The initial scan showed foci of increased FDG uptake in all patients, with Ann Arbor stage varying between I and IV. In the follow-up examination, all but one patient showed complete response to chemotherapy. PET image quality was rated as very good or excellent for all scans. Interrater agreement was excellent regarding Ann Arbor stage (κ = 0.97) and good regarding image quality (κ = 0.41).

Conclusion

PET/MR shows promising initial results for therapy response evaluation in lymphoma patients.     

Investigation of load prediction on the Mexico rotor using the technique of determination of the angle of attack

Blade element moment(BEM) is a widely used technique for prediction of wind turbine aerodynamics performance,the reliability of airfoil data is an important factor to improve the prediction accuracy of aerodynamic loads and power using a BEM code.The method of determination of angle of attack on rotor blades developed by SHEN,et al is successfully used to extract airfoil data from experimental characteristics on the MEXICO(Model experiments in controlled conditions) rotor.Detailed surface pressure and particle image velocimetry(PIV) flow fields at different rotor azimuth positions are examined to determine the sectional airfoil data.The present technique uses simultaneously both PIV data and blade pressure data that include the actual flow conditions(for example,tunnel effects),therefore it is more advantageous than other techniques which only use the blade loading(pressure data).The extracted airfoil data are put into a BEM code,and the calculated axial and tangential forces are compared to both computations using BEM with Glauert’s and SHEN’s tip loss correction models and experimental data.The comparisons show that the present method of determination of angle of attack is correct,and the re-calculated forces have good agreements with the experiment.     

How to Obtain a Mega-Intestine with Normal Morphology: In Silico Modelling of Postnatal Intestinal Growth in a Cd97-Transgenic Mouse

Intestinal cylindrical growth peaks in mice a few weeks after birth, simultaneously with crypt fission activity. It nearly stops after weaning and cannot be reactivated later. Transgenic mice expressing Cd97/Adgre5 in the intestinal epithelium develop a mega-intestine with normal microscopic morphology in adult mice. Here, we demonstrate premature intestinal differentiation in Cd97/Adgre5 transgenic mice at both the cellular and molecular levels until postnatal day 14. Subsequently, the growth of the intestinal epithelium becomes activated and its maturation suppressed. These changes are paralleled by postnatal regulation of growth factors and by an increased expression of secretory cell markers, suggesting growth activation of non-epithelial tissue layers as the origin of enforced tissue growth. To understand postnatal intestinal growth mechanistically, we study epithelial fate decisions during this period with the use of a 3D individual cell-based computer model. In the model, the expansion of the intestinal stem cell (SC) population, a prerequisite for crypt fission, is largely independent of the tissue growth rate and is therefore not spontaneously adaptive. Accordingly, the model suggests that, besides the growth activation of non-epithelial tissue layers, the formation of a mega-intestine requires a released growth control in the epithelium, enabling accelerated SC expansion. The similar intestinal morphology in Cd97/Adgre5 transgenic and wild type mice indicates a synchronization of tissue growth and SC expansion, likely by a crypt density-controlled contact inhibition of growth of intestinal SC proliferation. The formation of a mega-intestine with normal microscopic morphology turns out to originate in changes of autonomous and conditional specification of the intestinal cell fate induced by the activation of Cd97/Adgre5.