Retinoblastoma,deletion 13q14, and esterase D: Application of gene dosage effect to prenatal diagnosis

Esterase D (ESD) gene dosage studies were performed on amniotic cells from a fetus at risk for del 13q14. The mother was a balanced carrier of an insertion in chromosome #20: 46,XX,ins(20;13)(p12;q1307q14.3). She had already given birth to a monosomic child with retinoblastoma (Rb) and to a phenotypically normal child trisomic for the same 13q14 segment. Both sibs displayed the expected proportionate gene dosage effects for ESD. A 153% value of ESD activity was found in the amniotic cells indicating unambiguously that the fetus was not monosomic for segment 13q14 and therefore not at increased risk for Rb. The mother delivered a phenotypically normal child who was confirmed to be trisomic for segment 13q14 by cytogenetic analysis and by gene dosage studies for ESD in cord blood cells and in lymphoblastoid cells.     

Attentional performance of (C57BL/6Jx129Sv)F2 mice in the five-choice serial reaction time task

Impaired attention is evident in several neurological and psychiatric disorders. In the present study, attentional capabilities were measured in the operant five-choice serial reaction time task (5-CSRTT) in male (C57BL/6Jx129Sv)F2 hybrid (B6129F2) mice. Main aims were to validate and standardize the test in these mice: to setup procedures, measure potential beneficial effects of sub-chronic nicotine in degraded versions of the 5-CSRTT (by decreasing stimulus duration, inducing white noise and making the stimuli unpredictable) and study disruptive effects of additional administration of the muscarinic antagonist scopolamine. During the baseline pre-nicotine sessions, the B6129F2 mice attained a very good performance in the test (95% accuracy). As stimulus duration was reduced from 2 s to 1 s, response accuracy of the mice decreased. Mice treated with nicotine (0.16 mg/kg) attained significantly higher response accuracy and had a lower percentage of incorrect responses in comparison with the solvent-treated animals. No further beneficial effects of nicotine were found. Reduced response accuracy was also obtained when stimulus duration was reduced from 1 s to 0.5 s and when a variable intertrial interval was introduced. Noise interpolation between trials did not impair performance. Finally, scopolamine (0.16 mg/kg) disrupted attentional functioning. Although most studies have been performed in rats, these results add to the existing evidence that the 5-CSRTT can also be used to assess attentional performance in mice. This offers the opportunity to test transgenic and knockout mice with similar background as the B6129F2 as animal models of psychiatric and neurological diseases.     

Hyperpolarized 129Xe MRI of the human lung

By permitting direct visualization of the airspaces of the lung, magnetic resonance imaging (MRI) using hyperpolarized gases provides unique strategies for evaluating pulmonary structure and function. Although the vast majority of research in humans has been performed using hyperpolarized ³He, recent contraction in the supply of ³He and consequent increases in price have turned attention to the alternative agent, hyperpolarized ¹²⁹Xe. Compared to ³He, ¹²⁹Xe yields reduced signal due to its smaller magnetic moment. Nonetheless, taking advantage of advances in gas‐polarization technology, recent studies in humans using techniques for measuring ventilation, diffusion, and partial pressure of oxygen have demonstrated results for hyperpolarized ¹²⁹Xe comparable to those previously demonstrated using hyperpolarized ³He. In addition, xenon has the advantage of readily dissolving in lung tissue and blood following inhalation, which makes hyperpolarized ¹²⁹Xe particularly attractive for exploring certain characteristics of lung function, such as gas exchange and uptake, which cannot be accessed using ³He. Preliminary results from methods for imaging ¹²⁹Xe dissolved in the human lung suggest that these approaches will provide new opportunities for quantifying relationships among gas delivery, exchange, and transport, and thus show substantial potential to broaden our understanding of lung disease. Finally, recent changes in the commercial landscape of the hyperpolarized‐gas field now make it possible for this innovative technology to move beyond the research laboratory. J. Magn. Reson. Imaging 2013;37:313–331. © 2012 Wiley Periodicals, Inc.     

32‐channel phased‐array receive with asymmetric birdcage transmit coil for hyperpolarized xenon‐129 lung imaging

Hyperpolarized xenon‐129 has the potential to become a noninvasive contrast agent for lung MRI. In addition to its utility for imaging of ventilated airspaces, the property of xenon to dissolve in lung tissue and blood upon inhalation provides the opportunity to study gas exchange. Implementations of imaging protocols for obtaining regional parameters that exploit the dissolved phase are limited by the available signal‐to‐noise ratio, excitation homogeneity, and length of acquisition times. To address these challenges, a 32‐channel receive‐array coil complemented by an asymmetric birdcage transmit coil tuned to the hyperpolarized xenon‐129 resonance at 3 T was developed. First results of spin‐density imaging in healthy subjects and subjects with obstructive lung disease demonstrated the improvements in image quality by high‐resolution ventilation images with high signal‐to‐noise ratio. Parallel imaging performance of the phased‐array coil was demonstrated by acceleration factors up to three in 2D acquisitions and up to six in 3D acquisitions. Transmit‐field maps showed a regional variation of only 8% across the whole lung. The newly developed phased‐array receive coil with the birdcage transmit coil will lead to an improvement in existing imaging protocols, but moreover enable the development of new, functional lung imaging protocols based on the improvements in excitation homogeneity, signal‐to‐noise ratio, and acquisition speed. Magn Reson Med 70:576–583, 2013. © 2012 Wiley Periodicals, Inc.