XeNA: an automated ‘open-source’ 129Xe hyperpolarizer for clinical use

Here we provide a full report on the construction, components, and capabilities of our consortium’s “open-source” large-scale (~ 1 L/h) 129Xe hyperpolarizer for clinical, pre-clinical, and materials NMR/MRI (Nikolaou et al., Proc. Natl. Acad. Sci. USA, 110, 14150 (2013)). The ‘hyperpolarizer’ is automated and built mostly of off-the-shelf components; moreover, it is designed to be cost-effective and installed in both research laboratories and clinical settings with materials costing less than $125,000. The device runs in the xenon-rich regime (up to 1800 Torr Xe in 0.5 L) in either stopped-flow or single-batch mode—making cryo-collection of the hyperpolarized gas unnecessary for many applications. In-cell 129Xe nuclear spin polarization values of ~ 30%–90% have been measured for Xe loadings of ~ 300–1600 Torr. Typical 129Xe polarization build-up and T1 relaxation time constants were ~ 8.5 min and ~ 1.9 h respectively under our spin-exchange optical pumping conditions; such ratios, combined with near-unity Rb electron spin polarizations enabled by the high resonant laser power (up to ~ 200 W), permit such high PXe values to be achieved despite the high in-cell Xe densities. Importantly, most of the polarization is maintained during efficient HP gas transfer to other containers, and ultra-long 129Xe relaxation times (up to nearly 6 h) were observed in Tedlar bags following transport to a clinical 3 T scanner for MR spectroscopy and imaging as a prelude to in vivo experiments. The device has received FDA IND approval for a clinical study of chronic obstructive pulmonary disease subjects. The primary focus of this paper is on the technical/engineering development of the polarizer, with the explicit goals of facilitating the adaptation of design features and operative modes into other laboratories, and of spurring the further advancement of HP-gas MR applications in biomedicine

Temperature-ramped 129Xe spin-exchange optical pumping

We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode 129Xe hyperpolarizer utilizing three key temperature regimes: (i) “hot”where the 129Xe hyperpolarization rate is maximal, (ii) “warm”-where the 129Xe hyperpolarization approaches unity, and (iii) “cool” where hyperpolarized 129Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ∼1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized 129Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant γSEOP of 62.5 ± 3.7 × 10−3 min−1 vs 29.9 ± 1.2 × 10−3 min−1) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loadingcorresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ∼3.1 × 105 and ∼2.32 × 108 at the relevant fields for clinical imaging and HP 129Xe production of 3 T and 4 mT, respectively); moreover, the intercycle “dead” time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of 129Xe hyperpolarization or the experimental stability for automation-making this approach beneficial for improving the overall 129Xe production rate in clinical settings

Threonine Requirement of the Grower Turkey Tom

Two experiments were conducted to determine threonine requirement for maximum performance and breast and drumstick major muscle relative weights of turkey toms raised from 8-10wk and 11-13wk of age. Also plasma free amino acid concentration in response to feeding a diet with graded levels of threonine was measured. A corn-peanut meal diet was formulated to contain 0.59, 0.72, 0.85, 0.98 and 1.11% threonine and fed to Large White turkey males (British United Turkeys, BUT) in both trials. Each treatment was replicated among 5 and 8 individual cages in experiments 1 and 2, respectively. Two days prior to the end of each trial, blood was removed from the brachial vein of five toms per treatment and analyzed for plasma amino acid concentration. At the end of each experiment, final body weight and feed consumption were recorded and feed efficiency was computed. Birds were then sacrificed and pectoralis major and gastrocnemius muscles were weighed. The 0.85% dietary threonine resulted in the highest weight gain and feed efficiency ratio in the first trial. In the second experiment an increase (P&lt;0.05) in weight gain was also obtained by the 0.85% dietary threonine with no further significant improvement beyond that level. Therefore the current results indicate that the threonine requirement for maximum weight gain of turkey toms raised from 8 to 10 and 11 to 13wk of age is 0.85%. The changes in blood threonine concentration further supported the estimated requirement of threonine obtained from the performance data. Increasing dietary threonine from 0.59 to 1.11% during both growing periods, however, had no effect on pectoralis major or gastrocnemius muscles yield. In conclusion threonine requirement for maximum performance of the grower turkey tom raised from 8 to 13wk of age was 0.85% diet, a value slightly higher than that reported in the literature

Interrelations between the Microbiotas in the Litter and in the Intestines of Commercial Broiler Chickens ▿

The intestinal microbiota of broiler chickens and the microbiota in the litter have been well studied, but the interactions between these two microbiotas remain to be determined. Therefore, we examined their reciprocal effects by analyzing the intestinal microbiotas of broilers reared on fresh pine shavings versus reused litter, as well as the litter microbiota over a 6-week cycle. Composite ileal mucosal and cecal luminal samples from birds (n = 10) reared with both litter conditions (fresh versus reused) were collected at 7, 14, 21, and 42 days of age. Litter samples were also collected at days 7, 14, 21, and 42. The microbiotas were profiled and compared within sample types based on litter condition using PCR and denaturing gradient gel electrophoresis (PCR-DGGE). The microbiotas were further analyzed using 16S rRNA gene clone libraries constructed from microbiota DNA extracted from both chick intestinal and litter samples collected at day 7. Results showed significant reciprocal effects between the microbiotas present in the litter and those in the intestines of broilers. Fresh litter had more environmental bacteria, while reused litter contained more bacteria of intestinal origin. Lactobacillus spp. dominated the ileal mucosal microbiota of fresh-litter chicks, while a group of bacteria yet to be classified within Clostridiales dominated in the ileal mucosal microbiota in the reused-litter chicks. The Litter condition (fresh versus reused) seemed to have a more profound impact on the ileal microbiota than on the cecal microbiota. The data suggest that the influence of fresh litter on ileal microbiota decreased as broilers grew, compared with temporal changes observed under reused-litter rearing conditions