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.

Variability in management of T1 colorectal cancer in Wales

INTRODUCTION

The management of T1 colorectal cancer is controversial. Surgical resection should offer cure in the majority of patients and can stage lymph nodes accurately. Nevertheless, there can be significant associated morbidity and it potentially risks overtreating the patient. Endoscopic/local excision has significantly reduced morbidity but risks undertreating undetected metastatic lymph nodes, thereby compromising oncological outcomes. The aim of this study was to review the practice across Wales over a two-year period.

METHODS

Data on T1 tumours for the period of 2009-2011 were collected from the Cancer Network Information System Cymru.

RESULTS

A total of 161 patients were diagnosed as having T1 colorectal cancer (without prior neoadjuvant treatment). The median age was 68 years (range: 14-91 years) and 66% of the patients were male. Forty-eight (30%) of these tumours were screen detected. There were 112 colonic and 49 rectal tumours. Ninety-five patients with colonic tumours (85%) underwent major surgical resections, 51% of which were laparoscopic. Forty patients with rectal cancers (82%) underwent major surgical resection and 45% of these procedures were laparoscopic. The rest of the patients underwent local excision in the form of endoscopic polypectomy or transanal resection.

CONCLUSIONS

This study demonstrates that there is no consensus in the management of T1 disease across Wales. With the advent of screening and the development of more sophisticated endoscopic techniques, the decision of how to treat T1 colorectal cancer will become a more regular challenge for the colorectal multidisciplinary team. The treatment needs standardisation. For now, however, this balance of risk will need to be made on an individual patient basis.

Measurement of muon neutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV

We report a study of ν(μ) charged-current quasielastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a μ- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross section, dσ/dQ², and study the low energy particle content of the final state. Deviations are found between the measured dσ/dQ² and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.

Measurement of muon antineutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV

We have isolated ν(μ) charged-current quasielastic (QE) interactions occurring in the segmented scintillator tracking region of the MINERvA detector running in the NuMI neutrino beam at Fermilab. We measure the flux-averaged differential cross section, dσ/dQ², and compare to several theoretical models of QE scattering. Good agreement is obtained with a model where the nucleon axial mass, M(A), is set to 0.99 GeV/c² but the nucleon vector form factors are modified to account for the observed enhancement, relative to the free nucleon case, of the cross section for the exchange of transversely polarized photons in electron-nucleus scattering. Our data at higher Q² favor this interpretation over an alternative in which the axial mass is increased.

Abstract 1968: Inactivation of the tumor suppressor Lgl via PTEN loss promotes the invasiveness of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most aggressive and invasive form of brain tumor. From diagnosis the average survival time is about one year. While other forms of brain cancer can be successfully removed by surgical means, the invasive nature of GBM results in frequent relapses at secondary sites within the brain. PTEN loss is very common in GBM and leads to aberrant activation of the phosphoinositide 3-kinase pathway. Here we show that this event results in the constitutive phosphorylation and inactivation of the tumor suppressor lethal giant larvae (LGL). In Drosophila, loss of LGL causes both over-proliferation and increased invasiveness of epithelial and brain tissue. Studies in yeast and mammals have also shown a role for Lgl in vesicle trafficking and cell motility. Its role in the proliferation and invasiveness in human brain cancer has not been investigated previously. In both cell culture and in vivo subcutaneous mouse models, expression of a non-phosphorylatable, constitutively active form of LGL (LGL-3SA) did not significantly affect the proliferation of human U87MG glioblastoma cells. However, LGL-3SA expression did lead to a reduction in the invasiveness of U87MG cells in vitro. This appeared to be mediated in part by effects on matrix metalloproteinase trafficking, as LGL-3SA prevented the delivery of matrix metalloproteinase 14 (MMP14) to the leading edge of U87MG cells. The role of Lgl in primary glioblastoma stem-like cells was also assessed, as these cells retain their invasive properties in mouse xenografts and are therefore a more clinically relevant model of glioblastoma. All primary glioblastoma stem-like cells expressed Lgl. MMP14 expression was also detected in primary glioblastoma stem-like cells, and Lgl-3SA impaired its trafficking in these cells as well. Experiments are underway to assess the affects of Lgl-3SA expression on the in vivo invasiveness of intracranial xenograft tumours generated using glioblastoma stem-like cells. Our current in vitro data suggest that inactivation of Lgl is an essential downstream step mediating the increased invasiveness of PTEN negative glioblastoma. Inactivation of Lgl enhances invasiveness by increasing the delivery of MMP-14 to the cell surface, where it can promote the degradation of extracellular matrix directly and also indirectly by activation of other matrix metalloproteinases.

Citation Format: Alexander Gont, Jennifer Hanson, Mathieu Soucie, Amin Kassam, Vasco DaSilva, John Woulfe, Garth Nicholas, Sylvie Lavictoire, Ian Restall, Ian A. Lorimer. Inactivation of the tumor suppressor Lgl via PTEN loss promotes the invasiveness of glioblastoma multiforme. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1968. doi:10.1158/1538-7445.AM2013-1968

BRAF, PIK3CA, and PTEN status and benefit from cetuximab (CET) in the treatment of advanced colorectal cancer (CRC): Results from NCIC CTG/AGITG CO.17

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Background: CET, a monoclonal antibody targeting the epidermal growth factor receptor, improves overall survival (OS) and progression free survival (PFS) in patients (pts) with KRAS wild-type (WT) chemotherapy refractory CRC. BRAF and PIK3CA mutation status, and PTEN expression levels may further predict benefit from CET therapy. Methods: Available colorectal tumour samples were analyzed from a phase III trial of CET plus best supportive care (BSC) vs BSC alone (NEJM 2007; 357(20)). BRAF and PIK3CA mutations (MUT) identified in tumour-derived DNA using a high resolution melting analysis to identify amplicons with mutations were confirmed by sequencing. PTEN expression by immunohistochemistry (IHC) was performed on tissue microarrays constructed from available tumour blocks. For each biomarker, prognostic (treatment independent) effects were assessed in patients on the BSC alone arm. Predictive effects (benefit from CET) on OS and PFS among all patients and those in the KRAS wild-type subset were examined using a Cox model with tests for treatment-biomarker interaction, adjusting for covariates. Results: Of 401 pts assessed for BRAF status (70% of CO17 population), 13(3%) had mutations. Of 407 pts assessed for PIK3CA status (71% of CO17 population), 61(15%) had mutations. Of 205 pts assessed for PTEN (36% of CO17 population), 148(72%) were negative for IHC expression. No biomarker was prognostic for OS or PFS, and none were predictive of benefit from CET, either in the whole study population or the KRAS WT subset. Conclusions: In chemotherapy-refractory CRC, neither PIK3CA mutation status nor PTEN expression were predictive of benefit from CET therapy. BRAF mutations are uncommon in this setting. Larger sample sizes would be required to determine if BRAF status is predictive for CET benefit. [Table: see text]

BRCA1 protein levels and PIK3CA mutations as predictive biomarkers for response to neoadjuvant chemotherapy in locally advanced breast cancer: An exploratory analysis

BRCA1 overexpression and phosphoinositide 3-kinase (PIK3CA) pathway activation are involved in the resistance to DNA damaging agents. Thus, we hypothesized that BRCA1 protein expression and activating PIK3CA mutations are potential tumor biomarkers for the chemotherapeutic response to doxorubicin/cyclophosphamide plus docetaxel in locally advanced breast cancer. Informed consent was obtained and clinical, pathological and response data were collected. BRCA1 protein expression levels were assessed by immunohistochemistry of the archived tissue by two independent pathologists. The PIK3CA mutation status was assessed by nested PCR amplification and DNA sequencing. BRCA1 protein levels and the PIK3CA mutation status were correlated with pathological complete response and a partial response or better using the Chi-square test, Fisher's exact test and logistic regression. Of the 136 eligible participants, 59 samples could be analyzed. There was a trend of relatively low levels of BRCA1 protein achieving a pathological complete response (pCR), although this was not statistically significant [odds ratio (OR)=1.74; p=0.437]. Twenty-eight percent of patients had PIK3CA mutations, but no statistically significant association with pCR (OR=0.977; p=0.971) was noted. Neither BRCA1 protein levels (OR=1.18; p=0.818) nor PIK3CA mutations (OR=1.03; p=0.971) appeared to be associated with the likelihood of achieving a partial response or better from neoadjuvant chemotherapy. PIK3CA wild-type mutation status showed a trend towards an increased likelihood of not presenting with inflammatory disease (OR=5.34; p=0.101). In this exploratory study, neither BRCA1 protein expression levels nor the presence of PIK3CA mutations were significantly associated with chemotherapy response in locally advanced breast cancer. However, the relatively small sample size limits the overall interpretation.

Directional limits on persistent gravitational waves using LIGO S5 science data

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50)  strain(2) Hz(-1) and 5-35×10(-49)  strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

Abstract C1: BRCA1 protein levels and PI3KA mutations as predictive biomarkers for response to neoadjuvant chemotherapy in locally advanced breast cancer: An exploratory analysis

Background: Locally advanced breast cancer (LABC) is treated with neoadjuvant chemotherapy, with a goal of achieving a pathologic complete response (pCR) and a better outcome. Given the role of breast cancer 1 (BRCA1) overexpression and PI 3-kinase (PI3K) activation in the resistance to DNA damaging agents, we hypothesize that BRCA1 protein expression and activating PI3K mutations are potential tumor biomarkers for chemotherapy response in LABC.

Methods: For this exploratory study, informed consent was requested from 136 eligible patients identified between 2006 and 2008. Participants had demographic and response data collected and the pathologic characteristics of the tumor specimens before and after chemotherapy were evaluated. BRCA1 protein expression levels were assessed by immunohistochemistry of archival tissue. Specimens were evaluated by two separate pathologists for both staining intensity and distribution. BRCA1 protein levels were then tested for correlation with pCR and a partial response or better using a Chi Square Test and logistic regression analysis. PI3KA mutation status was assessed by isolating DNA from pathology sample sections followed by nested PCR amplification and DNA sequencing. PI3KA mutation status was then tested for correlation with pCR and a partial response or better using a Fisher Exact Test and a logistic regression analysis.

Results: Of the 136 eligible participants, 65 agreed to participate, with analyzable samples available in 59. Of these 59 patients, the median age was 51.6 years, 20.3% had inflammatory disease, 72.8% were ER positive, 61.0% were PR positive, 28.8% were HER2 positive and the median tumor grade was 2/3. All participants received 4 cycles of doxorubicin/cyclophosphamide and 4 cycles of docetaxel followed by 1 year of trastuzumab initiated with docetaxel if HER2 positive, except for one participant who received 6 cycles of carboplatin/taxotere due to a pre-existing cardiac dysfunction. 78.3% of participants had ≥30% response to therapy, with 23.7% achieving a pCR. BRCA1 protein expression was scored between 0–9. A minimal p-value approach established that samples scored ≤4 have relatively low levels of protein expression, while samples scored >4 have high levels. Low levels of BRCA1 protein had an Odds ratio (OR) = 1.74 of achieving a pCR compared to high levels, although this was not statistically significant (p-value=0.437). PI3KA mutations were not statistically associated with a likelihood of pCR (OR=0.977; p=0.971). Neither BRCA1 protein levels (OR=1.18; p=0.818) nor PI3KA mutations (OR=1.03; p=0.971) appeared to be associated with the likelihood of achieving a partial response or better to neoadjuvant chemotherapy. A mutation in PI3KA showed a trend towards an increased likelihood of not presenting with inflammatory disease (OR=5.34), although this result did not reach statistical significance (p=0.101).

Conclusions: In this exploratory study in LABC, neither BRCA1 protein expression levels nor the presence of PI3KA mutations appear to be associated with chemotherapy response. However, the relatively small sample size limits the overall interpretation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C1.

Information on response requirements compared with information on food density as a reinforcer of observing in pigeons

On a variable-interval schedule, pecking the key to the pigeon's right (observing response) produced red or green displays relating to the delivery of grain and its dependence on pecking the key to the left (food key). During various blocks of sessions, mixed (no stimulus change) schedules including the following pairs of components were temporarily converted by the observing response to their corresponding multiple (correlated stimuli) schedules: variable-interval 60-s, extinction; variable-interval 60-s, variable-time (response-independent) 60-s; extinction, variable-time 60-s. Differences in food delivery maintained substantial rates of responding on the observing key, without regard to pecking requirements on the food key. Although stimuli correlated with differences in the response requirement on the food key maintained higher observing rates than those maintained by uncorrelated stimuli, they were much lower than those based on food. The value of predictive stimuli as reinforcers is determined by the value of the events predicted. In particular, the cost of pecking appears to be low, and this may place limitations on the applicability of energy-based and economic models of behavior.