Lung transplantation with donation after circulatory determination of death donors and the impact of ex vivo lung perfusion

The growing demand for suitable lungs for transplantation drives the quest for alternative strategies to expand the donor pool. The aim of this study is to evaluate the outcomes of lung transplantation (LTx) with donation after circulatory determination of death (DCDD) and the impact of selective ex vivo lung perfusion (EVLP). From 2007 to 2013, 673 LTx were performed, with 62 (9.2%) of them using DCDDs (seven bridged cases). Cases bridged with mechanical ventilation/extracorporeal life support were excluded. From 55 DCDDs, 28 (51%) underwent EVLP. Outcomes for LTx using DCDDs and donation after neurological determination of death (DNDD) donors were similar, with 1 and 5-year survivals of 85% and 54% versus 86% and 62%, respectively (p = 0.43). Although comparison of survival curves between DCDD + EVLP versus DCDD-no EVLP showed no significant difference, DCDD + EVLP cases presented shorter hospital stay (median 18 vs. 23 days, p = 0.047) and a trend toward shorter length of mechanical ventilation (2 vs. 3 days, p = 0.059). DCDDs represent a valuable source of lungs for transplantation, providing similar results to DNDDs. EVLP seems an important technique in the armamentarium to safely increase lung utilization from DCDDs; however, further studies are necessary to better define the role of EVLP in this context.

Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Ω_{GW}(f)=Ω_{α}(f/f_{ref})^{α}, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of α=0, we constrain the energy density of the stochastic background to be Ω_{GW}(f)<5.6×10^{-6}. For the 600-1000 Hz band, Ω_{GW}(f)<0.14(f/900  Hz)^{3}, a factor of 2.5 lower than the best previously reported upper limits. We find Ω_{GW}(f)<1.8×10^{-4} using a spectral index of zero for 170-600 Hz and Ω_{GW}(f)<1.0(f/1300  Hz)^{3} for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

High-resolution diffusion-weighted imaging for monitoring breast cancer treatment response

RATIONALE AND OBJECTIVES

The aim of this work was to compare a high-resolution diffusion-weighted imaging (HR-DWI) acquisition (voxel size = 4.8 mm(3)) to a standard diffusion-weighted imaging (STD-DWI) acquisition (voxel size = 29.3 mm(3)) for monitoring neoadjuvant therapy-induced changes in breast tumors.

MATERIALS AND METHODS

Nine women with locally advanced breast cancer were imaged with both HR-DWI and STD-DWI before and after 3 weeks (early treatment) of neoadjuvant taxane-based treatment. Tumor apparent diffusion coefficient (ADC) metrics (mean and histogram percentiles) from both DWI methods were calculated, and their relationship to tumor volume change after 12 weeks of treatment (posttreatment) measured by dynamic contrast enhanced magnetic resonance imaging was evaluated with a Spearman's rank correlation.

RESULTS

The HR-DWI pretreatment 15th percentile tumor ADC (P = .03) and early treatment 15th, 25th, and 50th percentile tumor ADCs (P = .008, .010, .04, respectively) were significantly lower than the corresponding STD-DWI percentile ADCs. The mean tumor HR-ADC was significantly lower than STD-ADC at the early treatment time point (P = .02), but not at the pretreatment time point (P = .07). A significant early treatment increase in tumor ADC was found with both methods (P < .05). Correlations between HR-DWI tumor ADC and posttreatment tumor volume change were higher than the STD-DWI correlations at both time points and the lower percentile ADCs had the strongest correlations.

CONCLUSION

These initial results suggest that the HR-DWI technique has potential for improving characterization of low tumor ADC values over STD-DWI and that HR-DWI may be of value in evaluating tumor change with treatment.

High-resolution diffusion-weighted magnetic resonance imaging in patients with locally advanced breast cancer

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate differences in tumor depiction and measured tumor apparent diffusion coefficient (ADC) with the use of a high-resolution diffusion-weighted (DW) magnetic resonance imaging (MRI) sequence, compared to a standard DW MRI sequence, in patients with locally advanced breast cancer.

MATERIALS AND METHODS

Patients with locally advanced breast cancer were scanned with a reduced-field of view (rFOV) DW MRI sequence (high resolution) and a standard-field of view diffusion sequence (standard resolution), and differences between the two sequences were evaluated quantitatively (by calculating tumor ADC distribution parameters) and qualitatively (by radiologists' visual assessments of images).

RESULTS

Although the mean tumor ADC for both sequences was similar, differences were found in other parameters, including the 12.5th percentile (P = .042) and minimum tumor ADC (P = .003). Qualitatively, visualization of tumor morphologic detail, heterogeneity, and conspicuity was improved with rFOV DW MRI, and image quality was higher.

CONCLUSIONS

Differences in ADC distribution parameters and qualitative image features suggest that the sequences differ in their ability to capture tumor heterogeneity. These differences are not apparent when the mean is used to evaluate tumor ADC. In particular, differences found in lower ADC values are compatible with reduced partial voluming in rFOV DW MRI, suggesting that rFOV DW MRI may be valuable in imaging the lower ADCs expected to correspond to viable tumor in most invasive breast cancers.

P2-08-06: Improved Spatial Resolution Diffusion-Weighted Imaging for Characterizing Tumors and Treatment Response in Patients with Invasive Breast Cancer

Background: Diffusion weighted magnetic resonance imaging (DWI) is a non-invasive technique that is sensitive to tissue microstructure. Previous studies have shown that DWI adds positive predictive value in diagnostic studies of breast cancer and it has been shown to predict tumor response to neoadjuvant chemotherapy. While DWI shows promise for evaluating breast cancer, the technique suffers from limitations. Specifically, image distortion is common with the echo planar sequence available for DWI on clinical scanners, and spatial resolution is lower than that of other MRI sequences. Our group has optimized a high-resolution reduced field-of-view DWI acquisition, originally developed for the spine by Saritas et al., for breast imaging. The goal of this work was to compare high resolution (hr)-DWI) to standard resolution (std)-DWI for characterizing breast tumors.

Methods: Patients undergoing neoadjuvant chemotherapy were scanned with MRI before, during and after neoadjuvant chemotherapy as part of IRB-approved studies at our institution. Nine women were scanned with both hr-DWI and std-DWI before and after one cycle of chemotherapy. Apparent diffusion coefficient (ADC) maps were calculated from hr-DWI and std-DWI data using previously described methods. One tumor region of interest (ROI) was defined on the hr-DWI slice estimated to contain the largest tumor area. This tumor ROI was then applied to the corresponding slice and location on the std-DWI and hr-DWI ADC maps. Mean tumor ADC as well as 15th, 25th, 50th, 75th, and 90th percentile ADCs were calculated for both DWI acquisitions for all subjects.

Results: The mean tumor ADC values measured prior to treatment were similar for the hr-DWI and std-DWI acquisitions, however there was a significant difference between hr- and std-DWI 15th and 25th percentile ADC values (p= 0.0495, p=0.0717) For the early treatment time point, significant differences between the two DWI acquisitions were found for: mean tumor ADC, 15th, 25th, and 50th percentiles (p=0.0302, 0.0075, 0.0212, and 0.0488, respectively), with the most significant difference found for the lowest (15th) percentile measured. Tumor hr-DWI ADCs were consistently lower than std-DWI ADCs.

Discussion: These data show that although the mean ADC values calculated from the pre-treatment hr-DWI and std-DWI are similar, the lower percentile (15th, and 25th) ADC values are significantly lower for the hr-DWI acquisition. Our results also showed larger difference in lower percentile ADC values between the two sequences after one cycle of chemotherapy. The differences in the lower percentile ADC values calculated from the hr-DWI are consistent with reduced partial voluming between viable tumor tissue, which is characterized low ADC values, and normal fibroglandular tissue. This may be particularly important for post-treatment ADC measurements where tumor size may decrease, potentially making partial volume effects more pronounced. Continuing studies are evaluating the relationship between low percentile ADC values from hr-DWI and tumor stage and response to treatment.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-08-06.

Quantification of background enhancement in breast magnetic resonance imaging

PURPOSE

To present a novel technique for measuring tissue enhancement in breast fibroglandular tissue regions on contrast-enhanced breast magnetic resonance imaging (MRI) aimed at quantifying the enhancement of breast parenchyma, also known as "background enhancement."

MATERIALS AND METHODS

Our quantitative method for measuring breast MRI background enhancement was evaluated in a population of 16 healthy volunteers. We also demonstrate the use of our new technique in the case study of one subject classified as high risk for developing breast cancer who underwent 3 months of tamoxifen therapy.

RESULTS

We obtained quantitative measures of background enhancement in all cases. The high-risk patient exhibited a 37% mean reduction in background enhancement with treatment.

CONCLUSION

Our quantitative method is a robust and promising tool that may allow investigators to quantify and document the potential adverse effect of background enhancement on diagnostic accuracy in larger populations.

Dual bronchodilatory and pulmonary anti-inflammatory activity of RO5024118, a novel agonist at vasoactive intestinal peptide VPAC2 receptors

BACKGROUND AND PURPOSE

Vasoactive intestinal peptide is expressed in the respiratory tract and induces its effects via its receptors, VPAC(1) and VPAC(2). RO5024118 is a selective VPAC(2) receptor agonist derived via chemical modification of an earlier VPAC(2) agonist, RO0251553. In the present studies, we characterized the pharmacological activity of RO5024118.

EXPERIMENTAL APPROACH

Stability of RO5024118 to human neutrophil elastase was assessed. Bronchodilatory activity of RO5024118 was investigated in guinea pig and human isolated airway smooth muscle preparations and in a guinea pig bronchoconstriction model. Pulmonary anti-inflammatory activity of RO5024118 was investigated in a lipopolysaccharide mouse model and in a porcine pancreatic elastase (PPE) rat model.

KEY RESULTS

RO5024118 demonstrated increased stability to neutrophil elastase compared with RO0251553. In human and guinea pig isolated airway preparations, RO5024118 induced bronchodilatory effects comparable with RO0251553 and the long-acting β-agonist salmeterol and was significantly more potent than native vasoactive intestinal peptide and the short-acting β-agonist salbutamol. In 5-HT-induced bronchoconstriction in guinea pigs, RO5024118 exhibited inhibitory activity with similar efficacy as, and longer duration than, RO0251553. In a lipopolysaccharide-mouse model, RO5024118 inhibited neutrophil and CD8(+) cells and myeloperoxidase levels. In rats, intratracheal instillation of PPE induced airway neutrophilia that was resistant to dexamethasone. Pretreatment with RO5024118 significantly inhibited PPE-induced neutrophil accumulation.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that RO5024118 induces dual bronchodilatory and pulmonary anti-inflammatory activity and may be beneficial in treating airway obstructive and inflammatory diseases.

LINKED ARTICLES

This article is part of a themed section on Analytical Receptor Pharmacology in Drug Discovery. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2010.161.issue-6.

Diffusion-weighted MRI: influence of intravoxel fat signal and breast density on breast tumor conspicuity and apparent diffusion coefficient measurements

Promising recent investigations have shown that breast malignancies exhibit restricted diffusion on diffusion-weighted imaging (DWI) and may be distinguished from normal tissue and benign lesions in the breast based on differences in apparent diffusion coefficient (ADC) values. In this study, we assessed the influence of intravoxel fat signal on breast diffusion measures by comparing ADC values obtained using a diffusion-weighted single shot fast spin-echo sequence with and without fat suppression. The influence of breast density on ADC measures was also evaluated. ADC values were calculated for both tumor and normal fibroglandular tissue in a group of 21 women with diagnosed breast cancer. There were systematic underestimations of ADC for both tumor and normal breast tissue due to intravoxel contribution from fat signal on non-fat-suppressed DWI. This ADC underestimation was more pronounced for normal tissue values (mean difference=40%) than for tumors (mean difference=27%, P<.001) and was worse in women with low breast tissue density vs. those with extremely dense breasts (P<.05 for both tumor and normal tissue). Tumor conspicuity measured by contrast-to-noise ratio was significantly higher on ADC maps created with fat suppression and was not significantly associated with breast density. In summary, robust fat suppression is important for accurate breast ADC measures and optimal lesion conspicuity on DWI.

Synthesis and pharmacological effects of the enantiomers of the N-phenethyl analogues of the ortho and para e- and f-oxide-bridged phenylmorphans

The N-phenethyl analogues of (1R*,4aR*,9aS*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2,3-c]pyridin-6-ol and 8-ol and (1R*,4aR*,9aR*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2.3-c]pyridin-6-ol and 8-ol, the ortho- (43) and para-hydroxy e- (20), and f-oxide-bridged 5-phenylmorphans (53 and 26) were prepared in racemic and enantiomerically pure forms from a common precursor, the quaternary salt 12. Optical resolutions were accomplished by salt formation with suitable enantiomerically pure chiral acids or by preparative HPLC on a chiral support. The N-phenethyl (-)- para-e enantiomer (1S,4aS,9aR-(-)-20) was found to be a mu-opioid agonist with morphine-like antinociceptive activity in a mouse assay. In contrast, the N-phenethyl (-)-ortho-f enantiomer (1R,4aR,9aR-(-)-53) had good affinity for the mu-opioid receptor (K(i) = 7 nM) and was found to be a mu-antagonist both in the [(35)S]GTP-gamma-S assay and in vivo. The molecular structures of these rigid enantiomers were energy minimized with density functional theory at the level B3LYP/6-31G* level, and then overlaid on a known potent mu-agonist. This superposition study suggests that the agonist activity of the oxide-bridged 5-phenylmorphans can be attributed to formation of a seven membered ring that is hypothesized to facilitate a proton transfer from the protonated nitrogen to a proton acceptor in the mu-opioid receptor.

The effect of recipient's age on lung transplant outcome

Selection criteria for organ transplantation have evolved over time. Age has been revisited periodically. We studied the outcome of lung transplant adjusted by age in a single center transplant population. We matched the 42 lung graft recipients older than 60 years transplanted by July 1999 to younger controls by lung disease, transplant era within 2 years, type of transplant and gender. The female to male ratios were 17/25 among the older cohort (median age 61.6 years), and 15/27 (median age 51.9 years) among the matched younger. Survival analysis demonstrated a significant difference: at 1 year, 60% versus 86%, and at 5 years, 37% versus 57%, for older and younger, respectively, p=0.005. Excess annual mortality, calculated with the declining exponential approximation to life expectancy (DEALE), showed an older/younger ratio of 1.9. Eleven deaths occurred within 6 months among the older patients, 10 due to infection. After 6 months, there were 20 more deaths, 6 due to malignancy, 5 to Bronchiolitis Obliterans Syndrome (BOS), 3 to infection and 6 to other causes. Among the younger there were 6 deaths within 6 months and 12 more thereafter; among the latter, 8 were due to BOS. Despite stringent selection, lung transplant recipients older than 60 years show increased mortality even after adjusting for their expected higher age-related mortality.