Recent evidence indicates that a deficiency of 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) may influence asthma pathogenesis; however, its roles in regulating specific molecular transcription mechanisms remain unclear. We aimed to investigate the effect of 1,25(OH)2D3 on the expression and enzyme activity of histone deacetylase 2 (HDAC2) and its synergistic effects with dexamethasone (Dx) in the inhibition of inflammatory cytokine secretion in a rat asthma model. Healthy Wistar rats were randomly divided into 6 groups: control, asthma, 1,25(OH)2D3 pretreatment, 1,25(OH)2D3 treatment, Dx treatment, and Dx and 1,25(OH)2D3 treatment. Pulmonary inflammation was induced by ovalbumin (OVA) sensitization and challenge (OVA/OVA). Inflammatory cells and cytokines in the bronchoalveolar lavage (BAL) fluid and histological changes in lung tissue were examined. Nuclear factor kappa B (NF-κB) p65 and HDAC2 expression levels were assessed with Western blot analyses and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Enzyme activity measurements and immunohistochemical detection of HDAC2 were also performed. Our data demonstrated that 1,25(OH)2D3 reduced the airway inflammatory response and the level of inflammatory cytokines in BAL. Although NF-κB p65 expression was attenuated in the pretreatment and treatment groups, the expression and enzyme activity of HDAC2 were increased. In addition, 1,25(OH)2D3 and Dx had synergistic effects on the suppression of total cell infusion, cytokine release, and NF-κB p65 expression, and they also increased HDAC2 expression and activity in OVA/OVA rats. Collectively, our results indicated that 1,25(OH)2D3 might be useful as a novel HDAC2 activator in the treatment of asthma.

The diamagnetism of biological tissues reduces the homogeneity of the magnetic field and may limit the number of samples in multi-sample gradient-recalled echo (GRE) experiments. This study aims to 1) evaluate the magnetic field distortions and signal loss artifacts in GRE images of proximal water samples, and 2) develop a passive shimming device to overcome this limitation. The magnetic field distribution produced by a diamagnetic H2O sphere and a paramagnetic CuSO4 disk in a secondary phantom were mapped using GRE experiments and the phase reference method, and compared to the corresponding magnetostatics models. The water sphere produced a pronounced signal loss artifact in amplitude images. This artifact was significantly reduced when the paramagnetic disk was placed symmetrically between the water sphere and the secondary spherical phantom. The present study suggests that the use of paramagnetic shimming devices can help to minimize susceptibility-related MRI signal losses and to increase the number of samples in multi-sample MRI experiments. The volume susceptibility and the shape of paramagnetic shimming devices could be optimized for particular setups and samples accordingly.

The radiofrequency coil is a crucial component of the magnetic resonance imaging scanners, so that a solid knowledge on the design and physical characteristics is important for those interested in its development. A birdcage coil with a 10 cm radius and 4 legs (length = 12cm), and a separation between the copper strips of 4 cm, was developed for magnetic resonance imaging (MRI) of the human knee and tuned at the resonance frequency of protons at 4 Tesla (170.3 MHz). MR images were acquired with this coil in phantoms and in the knee of a healthy volunteer using a standard spin echo sequence, The phantom images demonstrated the high uniformity of the radiofrequency field with high signal-to-noise ratio, a characteristic of all birdcage RF coils. The in vivo knee images demonstrated that this birdcage geometry is ideal for knee imaging, promising MR images of the knee with higher spatial resolution at 4 Tesla. This work also demonstrates that volume coils are a good choice for high-field MRI applications.

Las antenas de radio frecuencia son una parte crucial para los sistemas de imagenología por resonancia magnética (IRM), por lo que la adquisición de conocimientos sólidos en el diseño y características es importante para aquellos interesados en su desarrollo. Construimos una antena del tipo jaula para IRM de rodilla humana. El prototipo esta compuesto de un diámetro de 10 cm, 4 elementos cuya longitud es de 12 cm y tienen una separación de 4 cm entre cada elemento y opera a la frecuencia de 170.3 MHz (4 Tesla). La viabilidad de la antena se probó con la adquisición de imágenes por resonancia magnética y de una rodilla sana, junto con secuencias estándar de tipo eco espín. Las imágenes mostraron alta calidad del cociente señal ruido y uniformidad del campo. Las imágenes adquiridas de la rodilla demostraron que la geometría tipo jaula es ideal para obtener imagenes de rodilla con alto cociente señal ruido en altos campos magnéticos. Este trabajo de investigación muestra que las antenas de volumen son una buena opción para aplicaciones de IRM de altos campos.