β Decay of ^{61}V and its Role in Cooling Accreted Neutron Star Crusts

The interpretation of observations of cooling neutron star crusts in quasipersistent x-ray transients is affected by predictions of the strength of neutrino cooling via crust Urca processes. The strength of crust Urca neutrino cooling depends sensitively on the electron-capture and β-decay ground-state-to-ground-state transition strengths of neutron-rich rare isotopes. Nuclei with a mass number of A=61 are predicted to be among the most abundant in accreted crusts, and the last remaining experimentally undetermined ground-state-to-ground-state transition strength was the β decay of ^{61}V. This Letter reports the first experimental determination of this transition strength, a ground-state branching of 8.1_{-3.1}^{+4.0}%, corresponding to a log ft value of 5.5_{-0.2}^{+0.2}. This result was achieved through the measurement of the β-delayed γ rays using the total absorption spectrometer SuN and the measurement of the β-delayed neutron branch using the neutron long counter system NERO at the National Superconducting Cyclotron Laboratory at Michigan State University. This method helps to mitigate the impact of the pandemonium effect in extremely neutron-rich nuclei on experimental results. The result implies that A=61 nuclei do not provide the strongest cooling in accreted neutron star crusts as expected by some predictions, but that their cooling is still larger compared to most other mass numbers. Only nuclei with mass numbers 31, 33, and 55 are predicted to be cooling more strongly. However, the theoretical predictions for the transition strengths of these nuclei are not consistently accurate enough to draw conclusions on crust cooling. With the experimental approach developed in this work, all relevant transitions are within reach to be studied in the future.

Mirror-symmetry violation in bound nuclear ground states

Conservation laws are deeply related to any symmetry present in a physical system^1,2. Analogously to electrons in atoms exhibiting spin symmetries³, it is possible to consider neutrons and protons in the atomic nucleus as projections of a single fermion with an isobaric spin (isospin) of t = 1/2 (ref. ⁴). Every nuclear state is thus characterized by a total isobaric spin T and a projection T_z-two quantities that are largely conserved in nuclear reactions and decays^5,6. A mirror symmetry emerges from this isobaric-spin formalism: nuclei with exchanged numbers of neutrons and protons, known as mirror nuclei, should have an identical set of states⁷, including their ground state, labelled by their total angular momentum J and parity π. Here we report evidence of mirror-symmetry violation in bound nuclear ground states within the mirror partners strontium-73 and bromine-73. We find that a J^π = 5/2^- spin assignment is needed to explain the proton-emission pattern observed from the T = 3/2 isobaric-analogue state in rubidium-73, which is identical to the ground state of strontium-73. Therefore the ground state of strontium-73 must differ from its J ^π = 1/2^- mirror bromine-73. This observation offers insights into charge-symmetry-breaking forces acting in atomic nuclei.

Abstract P3-08-07: ATM mutations contribution to hereditary breast-pancreatic cancer

BACKGROUND: Germline mutations in PALB2, BRCA2 and STK11 are well established as increasing risk of both breast and pancreatic cancer. More recently, ATM and BRCA1 mutations have also been associated with risk, but literature is limited. We investigated the prevalence of pathogenic mutations and likely pathogenic variants (“mutations”) in BRCA1/2, PALB2, STK11 and ATM, comparing mutation occurrence in individuals with diagnoses of breast cancer alone to those with both breast and pancreatic cancer primaries. Prevalence of CDKN2A (p16) mutations was also evaluated in the breast–pancreatic cohort because of its contribution to hereditary pancreatic cancer.

METHODS: Clinical histories and test results were reviewed for patients undergoing multi-gene panel testing at one clinical laboratory between April 2012 and June 2015. The study population was limited to women with breast cancer only (n=27,573) and women with both breast and pancreatic cancer (n=97) without other primaries. Patients underwent comprehensive analysis of 5-49 genes, depending on the panel ordered. Demographic and clinical information was provided by clinicians on test requisition forms and pedigrees/clinic notes if provided. Gene-specific mutation frequencies were compared between women with breast cancer only and women with breast and pancreatic cancer using Fisher's exact test.

RESULTS: Mutations were identified in BRCA1, BRCA2, PALB2 or ATM in 13 of the 97 breast - pancreatic cancer probands (13.4%) and 1,255 of the 27,573 breast cancer probands (4.6%). Gene-specific mutation frequencies and statistical comparisons may be found in Table 1. ATM mutations were significantly more likely to be identified in women with breast and pancreatic cancer compared to breast cancer alone (Table 1). Interestingly, no CDKN2A or STK11 mutations were identified in the breast plus pancreatic cohort, although this may have been limited by the small number of individuals tested for this gene. Of those 13 women with breast and pancreatic cancers who had identified mutations, 11 (85%) had diagnoses of breast cancer over age 50.

Table 1. Mutation FrequenciesGeneMutation Frequence n/N (%)Mutation Frequence n/N (%)pOR (95% PI) Breast & PancreaticBreast Only  ATM6/89 (6.74%)209/17,570 (1.19%)0.000766.00(2.12,13.85)BRCA12/90 (2.22 %)429/26,336 (1.63%)0.661.37(0.16,5.14)BRCA24/90 (4.44%)442/26,336 (1.68%)0.0662.72 (0.72,7.28)CDKN2A0/54 (0.00%)13/3,965 (0.33%)10.00 (0, 24.70)PALB21/891.12% 175/17,570 (1%)0.591.13(0.03, 6.54)STK110/860.00% 0/16,931 (0.00)1Inf (0, Inf)

CONCLUSION: This exploratory study substantiates the association of deleterious germline ATM mutations with predisposition to both breast and pancreatic cancers. These results also suggest that mutations in ATM may account for a larger portion of inherited breast and pancreatic cancer kindreds than mutations in other well-described genes such as BRCA2, PALB2 and STK11. A personal history of breast and pancreatic cancer may warrant the expansion of current NCCN testing criteria as a single indicator for germline testing, and that pancreatic screening consortia (CAPS) consider inclusion of ATM mutations in screening recommendations.

Citation Format: Gordon OK, Childers K, McFarland R, Laduca H. ATM mutations contribution to hereditary breast-pancreatic cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-08-07.

Evaluation of a single-pass intestinal-perfusion method in rat for the prediction of absorption in man

Prediction of the fraction of dose absorbed from the intestine (Fa) in man is essential in the early drug discovery stage. In-vitro assays in Caco-2 and MDCK cells are routinely used for that purpose, and their predictive value has been reported. However, in-situ techniques might provide a more accurate estimation of Fa. In this study, we evaluated a single-pass intestinal-perfusion (SPIP) method in the rat for its use in the prediction of absorption in man and compared it with a previous report using cell-based assays. Effective permeability coefficients (Peff) were determined in rats for 14 compounds, and ranged from 0.043x 10(-4) cm s(-1) to 1.67 x 10(-4) cm s(-1). These values strongly correlated (r2 = 0.88) with reported Peff values for man. In addition, the Spearman rank correlation coefficient calculated for in-situ-derived Peff and absorption in man was 0.92 while for the previously tested in-vitro Caco-2 and MDCK systems vs absorption in man, the correlation coefficients were 0.61 and 0.59, respectively. SPIP provided a better prediction of human absorption than the cell-based assays. This method, although time consuming, could be used as a secondary test for studying the mechanisms governing the absorption of new compounds, and for predicting more accurately the fraction absorbed in man.

Comparison of blood-culture contamination rates in a pediatric emergency room: newly inserted intravenous catheters versus venipuncture

We compared contamination rates of blood cultures obtained either from newly inserted intravenous catheters or via venipuncture. Of 2,431 blood cultures, the overall contamination rate was 2.7% (intravenous catheter, 3.4%; venipuncture, 2.0%; P=.043). The site of lowest contamination was the antecubital fossa, making this the optimal choice for blood-culture sampling.