226 research outputs found
Electrified BPS Giants: BPS configurations on Giant Gravitons with Static Electric Field
We consider D3-brane action in the maximally supersymmetric type IIB
plane-wave background. Upon fixing the light-cone gauge, we obtain the
light-cone Hamiltonian which is manifestly supersymmetric. The 1/2 BPS
solutions of this theory (solutions which preserve 16 supercharges) are either
of the form of spherical three branes, the giant gravitons, or zero size point
like branes. We then construct specific classes of 1/4 BPS solutions of this
theory in which static electric field on the brane is turned on. These
solutions are deformations about either of the two 1/2 BPS solutions. In
particular, we study in some detail 1/4 BPS configurations with electric dipole
on the three sphere giant, i.e. BIons on the giant gravitons, which we hence
call BIGGons. We also study BPS configurations corresponding to turning on a
background uniform constant electric field. As a result of this background
electric field the three sphere giant is deformed to squashed sphere, while the
zero size point like branes turn into circular or straight fundamental strings
in the plane-wave background, with their tension equal to the background
electric field.Comment: 32 pages, 1 eps figure; v2: Presentation of derivation of light-cone
Hamiltonian improved, Refs adde
A proposal for M2-brane-anti-M2-brane action
We propose a manifestly SO(8) invariant BF type Lagrangian for describing the
dynamics of M2-brane-anti-M2-brane system in flat spacetime. When one of the
scalars which satisfies a free-scalar equation takes a large expectation value,
the M2-brane-anti-M2-brane action reduces to the tachyon DBI action of
D2-brane-anti-D2-brane system in flat spacetime.Comment: 12 pages, latex file, the version to appear in PL
Polymorphic Variation of Genes in the Fibrinolytic System and the Risk of Ovarian Cancer
INTRODUCTION: The etiology of ovarian cancer is largely unknown. One hypothesis is that the inefficient removal of the blood clots and fibrin products which are deposited in the vicinity of the ovary by retrograde menstruation might be associated with an increased risk of ovarian cancer. Several single nucleotide polymorphisms within genes which comprise the fibrinolytic system have been shown to have functional effects on the rate of blood clot degradation. These were considered to be candidate genes in the present study. AIM: We studied the genotype distributions of 12 functional SNPs of four genes (tPA, uPA PAI1 and TAFI) among 775 ovarian cancer cases and 889 controls. RESULTS: No significant associations were seen between any of the ten SNPs and the risk of ovarian cancer as a whole, or in any histologic subgroup. DISCUSSION: Germline known functional variants of genes in the fibrinolytic system are not associated with risk of ovarian cancer
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A BRCA1 deficient-like signature is enriched in breast cancer brain metastases and predicts DNA damage-induced poly (ADP-ribose) polymerase inhibitor sensitivity
Introduction: There is an unmet clinical need for biomarkers to identify breast cancer patients at an increased risk of developing brain metastases. The objective is to identify gene signatures and biological pathways associated with human epidermal growth factor receptor 2-positive (HER2+) brain metastasis. Methods: We combined laser capture microdissection and gene expression microarrays to analyze malignant epithelium from HER2+ breast cancer brain metastases with that from HER2+ nonmetastatic primary tumors. Differential gene expression was performed including gene set enrichment analysis (GSEA) using publicly available breast cancer gene expression data sets. Results: In a cohort of HER2+ breast cancer brain metastases, we identified a gene expression signature that anti-correlates with overexpression of BRCA1. Sequence analysis of the HER2+ brain metastases revealed no pathogenic mutations of BRCA1, and therefore the aforementioned signature was designated BRCA1 Deficient-Like (BD-L). Evaluation of an independent cohort of breast cancer metastases demonstrated that BD-L values are significantly higher in brain metastases as compared to other metastatic sites. Although the BD-L signature is present in all subtypes of breast cancer, it is significantly higher in BRCA1 mutant primary tumors as compared with sporadic breast tumors. Additionally, BD-L signature values are significantly higher in HER2-/ER- primary tumors as compared with HER2+/ER + and HER2-/ER + tumors. The BD-L signature correlates with breast cancer cell line pharmacologic response to a combination of poly (ADP-ribose) polymerase (PARP) inhibitor and temozolomide, and the signature outperformed four published gene signatures of BRCA1/2 deficiency. Conclusions: A BD-L signature is enriched in HER2+ breast cancer brain metastases without pathogenic BRCA1 mutations. Unexpectedly, elevated BD-L values are found in a subset of primary tumors across all breast cancer subtypes. Evaluation of pharmacological sensitivity in breast cancer cell lines representing all breast cancer subtypes suggests the BD-L signature may serve as a biomarker to identify sporadic breast cancer patients who might benefit from a therapeutic combination of PARP inhibitor and temozolomide and may be indicative of a dysfunctional BRCA1-associated pathway
Nambu-Poisson Bracket and M-Theory Branes Coupled to Antisymmetric Fluxes
By using the recently proposed prescription arXiv:0804.3629 for obtaining the
brane action from multiple branes action in BLG theory, we examine
such transition when 11 Dimensional background antisymmetric fluxes couple to
the brane world volume. Such couplings was suggested in arXiv:0805.3427
where it was used the fact that various fields in BLG theory are valued in a
Lie 3-algebra. We argue that this action and promoting it by Nambu-Poisson
bracket gives the expected coupling of fluxes with brane at least at weak
coupling limit. We also study some other aspects of the action for example, the
gauge invariance of the theory.Comment: 14 page
On non-linear action of multiple M2-branes
A nonlinear SO(8) invariant BF type Lagrangian for describing the dynamics of
N M2-branes in flat spacetime has been proposed recently in the literature
which is an extension of the non-abelian DBI action of N D2-branes. This action
includes only terms with even number of the totally antisymmetric tensor
M^{IJK}. We argue that the action should contain terms with odd number of
M^{IJL} as well. We modify the action to include them.Comment: 8 pages, latex file; v4: another simple matrix for s^{IJ} has been
found, some comments adde
Laboratory features of severe vs. non-severe COVID-19 patients in Asian populations: a systematic review and meta-analysis
BACKGROUND: More severe cases of COVID- 19 are more likely to be hospitalized and around one-fifth, needing ICU admission. Understanding the common laboratory features of COVID-19 in more severe cases versus non-severe patients could be quite useful for clinicians and might help to predict the model of disease progression. This systematic review and meta-analysis aimed to compare the laboratory test findings in severe vs. non-severe confirmed infected cases of COVID-19. METHODS: Electronic databases were systematically searched in PubMed, EMBASE, Scopus, Web of Science, and Google Scholar from the beginning of 2019 to 3rd of March 2020. Heterogeneity across included studies was determined using Cochrane's Q test and the I2 statistic. We used the fixed or random-effect models to pool the weighted mean differences (WMDs) or standardized mean differences and 95% confidence intervals (CIs). FINDINGS: Out of a total of 3009 citations, 17 articles (22 studies, 21 from China and one study from Singapore) with 3396 ranging from 12 to1099 patients were included. Our meta-analyses showed a significant decrease in lymphocyte, monocyte, and eosinophil, hemoglobin, platelet, albumin, serum sodium, lymphocyte to C-reactive protein ratio (LCR), leukocyte to C-reactive protein ratio (LeCR), leukocyte to IL-6 ratio (LeIR), and an increase in the neutrophil, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, blood urea nitrogen (BUN), creatinine (Cr), erythrocyte Sedimentation Rate (ESR), C-reactive protein (CRP), Procalcitonin (PCT), lactate dehydrogenase (LDH), fibrinogen, prothr
Gene sequencing for pathogenic variants among adults with breast and ovarian cancer in the caribbean
Importance: Rates of breast and ovarian cancer are high in the Caribbean; however, to date, few published data quantify the prevalence of inherited cancer in the Caribbean population. Objective: To determine whether deleterious variants in genes that characterize the hereditary breast and ovarian cancer syndrome are associated with the development of breast and ovarian cancer in the English- and Creole-speaking Caribbean populations. Design, Setting, and Participants: This multisite genetic association study used data from germline genetic test results between June 2010 and June 2018 in the Bahamas, Cayman Islands, Barbados, Dominica, Jamaica, Haiti, and Trinidad and Tobago. Next-generation sequencing on a panel of 30 genes and multiplex ligation-dependent probe amplification (BRCA1 and BRCA2) were performed. Medical records were reviewed at time of study enrollment. Women and men diagnosed with breast and ovarian cancer with at least 1 grandparent born in the participating study sites were included; 1018 individuals were eligible and consented to participate in this study. Data were analyzed from November 4, 2019, to May 6, 2020. Exposures: Breast and/or ovarian cancer diagnosis Main Outcomes and Measures: Rate of inherited breast and ovarian cancer syndrome and spectrum and types of variants. Results: Of 1018 participants, 999 (98.1%) had breast cancer (mean [SD] age, 46.6 [10.8] years) and 21 (2.1%) had ovarian cancer (mean [SD] age, 47.6 [13.5] years). Three individuals declined to have their results reported. A total of 144 of 1015 (14.2%) had a pathogenic or likely pathogenic (P/LP) variant in a hereditary breast and ovarian cancer syndrome gene. A total of 64% of variant carriers had P/LP variant in BRCA1, 23% in BRCA2, 9% in PALB2 and 4% in RAD51C, CHEK2, ATM, STK11 and NBN. The mean (SD) age of variant carriers was 40.7 (9.2) compared with 47.5 (10.7) years in noncarriers. Individuals in the Bahamas had the highest proportion of hereditary breast and ovarian cancer (23%), followed by Barbados (17.9%), Trinidad (12%), Dominica (8.8%), Haiti (6.7%), Cayman Islands (6.3%), and Jamaica (4.9%). In Caribbean-born women and men with breast cancer, having a first- or second-degree family member with breast cancer was associated with having any BRCA1 or BRCA2 germline variant (odds ratio, 1.58; 95% CI, 1.24-2.01; P \u3c.001). A BRCA1 vs BRCA2 variant was more strongly associated with triple negative breast cancer (odds ratio, 6.33; 95% CI, 2.05-19.54; P =.001). Conclusions and Relevance: In this study, among Caribbean-born individuals with breast and ovarian cancer, 1 in 7 had hereditary breast and ovarian cancer. The proportion of hereditary breast and ovarian cancer varied by island and ranged from 23% in the Bahamas to 4.9% in Jamaica. Each island had a distinctive set of variants.
Investigating the causal role of MRE11A p.E506* in breast and ovarian cancer
The nuclease MRE11A is often included in genetic test panels for hereditary breast and ovarian cancer (HBOC) due to its BRCA1-related molecular function in the DNA repair pathway. However, whether MRE11A is a true predisposition gene for HBOC is still questionable. We determined to investigate this notion by dissecting the molecular genetics of the c.1516G > T;p.E506* truncating MRE11A variant, that we pinpointed in two unrelated French-Canadian (FC) HBOC patients. We performed a case-control study for the variant in ~ 2500 breast, ovarian, and endometrial cancer patients from the founder FC population of Quebec. Furthermore, we looked for the presence of second somatic alterations in the MRE11A gene in the tumors of the carriers. In summary, these investigations suggested that the identified variant is not associated with an increased risk of developing breast or ovarian cancer. We finally performed a systematic review for all the previously reported MRE11A variants in breast and ovarian cancer. We found that MRE11A germline variants annotated as pathogenic on ClinVar often lacked evidence for such classification, hence misleading the clinical management for affected patients. In summary, our report suggests the lack of clinical utility of MRE11A testing in HBOC, at least in the White/Caucasian populations
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