The carbon-to-oxygen ratio (C/O) in a planet provides critical information about its primordial origins and subsequent evolution. A primordial C/O greater than 0.8 causes a carbide-dominated ...interior, as opposed to the silicate-dominated composition found on Earth; the atmosphere can also differ from those in the Solar System. The solar C/O is 0.54 (ref. 3). Here we report an analysis of dayside multi-wavelength photometry of the transiting hot-Jupiter WASP-12b (ref. 6) that reveals C/O ≥ 1 in its atmosphere. The atmosphere is abundant in CO. It is depleted in water vapour and enhanced in methane, each by more than two orders of magnitude compared to a solar-abundance chemical-equilibrium model at the expected temperatures. We also find that the extremely irradiated atmosphere (T > 2,500 K) of WASP-12b lacks a prominent thermal inversion (or stratosphere) and has very efficient day-night energy circulation. The absence of a strong thermal inversion is in stark contrast to theoretical predictions for the most highly irradiated hot-Jupiter atmospheres.
Cholera toxin (CT) is an AB-type protein toxin that contains a catalytic A1 subunit, an A2 linker, and a cell-binding B homopentamer. The CT holotoxin is released into the extracellular environment, ...but CTA1 attacks a target within the cytosol of a host cell. We recently reported that grape extract confers substantial resistance to CT. Here, we used a cell culture system to identify twelve individual phenolic compounds from grape extract that inhibit CT. Additional studies determined the mechanism of inhibition for a subset of the compounds: two inhibited CT binding to the cell surface and even stripped CT from the plasma membrane of a target cell; two inhibited the enzymatic activity of CTA1; and four blocked cytosolic toxin activity without directly affecting the enzymatic function of CTA1. Individual polyphenolic compounds from grape extract could also generate cellular resistance to diphtheria toxin, exotoxin A, and ricin. We have thus identified individual toxin inhibitors from grape extract and some of their mechanisms of inhibition against CT.
Cholera toxin (Ctx) is an AB‐type protein toxin that acts as an adenosine diphosphate (ADP)‐ribosyltransferase to disrupt intracellular signalling in the target cell. It moves by vesicle carriers ...from the cell surface to the endoplasmic reticulum (ER) of an intoxicated cell. The catalytic CtxA1 subunit then dissociates from the rest of the toxin, unfolds, and activates the ER‐associated degradation system for export to the cytosol. Translocation occurs through an unusual ratchet mechanism in which the cytosolic chaperone Hsp90 couples CtxA1 refolding with CtxA1 extraction from the ER. Here, we report that Hsp90 recognises two peptide sequences from CtxA1: an N‐terminal RPPDEI sequence (residues 11–16) and an LDIAPA sequence in the C‐terminal region (residues 153–158) of the 192 amino acid protein. Peptides containing either sequence effectively blocked Hsp90 binding to full‐length CtxA1. Both sequences were necessary for the ER‐to‐cytosol export of CtxA1. Mutagenesis studies further demonstrated that the RPP residues in the RPPDEI motif are required for CtxA1 translocation to the cytosol. The LDIAPA sequence is unique to CtxA1, but we identified an RPPDEI‐like motif at the N‐ or C‐termini of the A chains from four other ER‐translocating toxins that act as ADP‐ribosyltransferases: pertussis toxin, Escherichia coli heat‐labile toxin, Pseudomonas aeruginosa exotoxin A, and Salmonella enterica serovar Typhimurium ADP‐ribosylating toxin. Hsp90 plays a functional role in the intoxication process for most, if not all, of these toxins. Our work has established a defined RPPDEI binding motif for Hsp90 that is required for the ER‐to‐cytosol export of CtxA1 and possibly other toxin A chains as well.
Spitzer Secondary Eclipses of WASP-18b Nymeyer, Sarah; Harrington, Joseph; Hardy, Ryan A ...
The Astrophysical journal,
11/2011, Letnik:
742, Številka:
1
Journal Article, Web Resource
Recenzirano
Odprti dostop
The transiting exoplanet WASP-18b was discovered in 2008 by the Wide Angle Search for Planets project. The Spitzer Exoplanet Target of Opportunity Program observed secondary eclipses of WASP-18b ...using Spitzer's Infrared Array Camera in the 3.6 Delta *mm and 5.8 Delta *mm bands on 2008 December 20, and in the 4.5 Delta *mm and 8.0 Delta *mm bands on 2008 December 24. We report eclipse depths of 0.30% ? 0.02%, 0.39% ? 0.02%, 0.37% ? 0.03%, 0.41% ? 0.02%, and brightness temperatures of 3100 ? 90, 3310 ? 130, 3080 ? 140, and 3120 ? 110 K in order of increasing wavelength. WASP-18b is one of the hottest planets yet discovered--as hot as an M-class star. The planet's pressure-temperature profile most likely features a thermal inversion. The observations also require WASP-18b to have near-zero albedo and almost no redistribution of energy from the day side to the night side of the planet.
We performed a systematic review and meta-analysis of deep lobe parotid tumors to evaluate their unique characteristics.
PubMed/Medline, Embase, Web of Sciences, and Cochrane Library databases were ...queried for relevant literature.
Studies were individually assessed by 2 independent reviewers. Risk of bias was assessed with the Cochrane bias tool, GRADE criteria, and MINORS criteria. Results were reported according to the PRISMA guidelines. Statistical analysis was performed by comparing rates of malignancy between deep and superficial lobe tumors.
In total, 8 studies including 379 deep lobe parotid tumors met inclusion criteria. Mean age at diagnosis was 44.9 years. Computed tomography scan was the most common imaging modality. Preoperative diagnostic fine-needle aspiration was utilized in 39.4% of patients and demonstrated high sensitivity for malignant disease. The most common approach was subtotal parotidectomy with facial nerve preservation (58.9%). The rate of malignancy was 26.6%, which was significantly higher than that of the superficial lobe tumors in this study (risk ratio, 1.25; 95% CI, 1.01-1.56). The rate of temporary postoperative facial nerve weakness between deep and superficial lobe tumors was 32.5% and 11.7%, respectively.
Deep lobe parotid tumors had a 26.6% rate of malignancy. On meta-analysis, deep lobe tumors appeared to have higher rates of malignancy than superficial lobe tumors. Surgical excision of deep lobe tumors showed increased rates of temporary facial nerve paresis as compared with superficial lobe tumors. Computed tomography scan was the most common imaging modality. There were limited data regarding the utility of fine-needle aspiration.
The aim of this study was to examine HPV vaccine administration practices since FDA approval to age 45 and assess knowledge regarding HPV and its association with oropharyngeal cancer.
A survey was ...distributed to 86 primary care physicians at Loyola University Medical Center. The survey contained 11 questions designed to capture HPV vaccination practices, knowledge of FDA approval, and barriers to vaccination.
46 (53%) physicians completed the survey and 45 responses were included. Among respondents who treat males ages 9–21 and females ages 9–26, the vaccination is widely recommended with >95% always or almost always recommending the vaccination. Among those treating males >21, and females >26, 52% and 35% of physicians recommend vaccination to these cohorts, respectively. Only 17% and 26% of respondents would recommend the vaccine to men and women respectively up to age 45. 100% of respondents recognize an association between HPV and cervical cancer, and 90% of respondents recognize HPV's association with oropharyngeal cancer. However, respondents also associate HPV with oral cavity and laryngeal cancer. 28% of respondents said parents are barriers to vaccination, while 7% said that insurance is a barrier.
HPV vaccination is widely recommended by physicians at our institution; however, for men older than 21 and women older than 26, vaccination recommendation rates decrease, and relatively few physicians would offer the vaccination up to age 45. Primary care physicians at our institution recognize HPV's close association to oropharyngeal cancer. Barriers to vaccination are primarily negative perception of the vaccine by patients and parents.
ABSTRACT
RZ2109 is the first of several extragalactic globular clusters shown to host an ultraluminous X-ray source. RZ2109 is particularly notable because optical spectroscopy shows it has broad, ...luminous O iii λλ4959,5007 emission, while also having no detectable hydrogen emission. The X-ray and optical characteristics of the source in RZ2109 make it a good candidate for being a stellar mass black hole accreting from a white dwarf donor (i.e. an ultracompact black hole X-ray binary). In this paper we present optical spectroscopic monitoring of the O iii5007 emission line from 2007 to 2018. We find that the flux of the emission line is significantly lower in recent observations from 2016 to 2018 than it was in earlier observations in 2007–2011. We also explore the behaviour of the emission line shape over time. Both the core and the wings of the emission line decline over time, with some evidence that the core declines more rapidly than the wings. However, the most recent observations (in 2019) unexpectedly show the emission line core rebrightening
ABSTRACT
The treatment of advanced laryngeal cancer has undergone a paradigm shift in recent years, with an increase in chemoradiation for organ preservation and a decrease in primary surgery. This ...review will summarize the contemporary management of advanced laryngeal cancer and discuss treatment‐related toxicity and strategies to improve outcomes.
Level of Evidence
NA.
ABSTRACT
Transitional millisecond pulsars are millisecond pulsars that switch between a rotation-powered millisecond pulsar state and an accretion-powered X-ray binary state, and are thought to be an ...evolutionary stage between neutron star low-mass X-ray binaries and millisecond pulsars. So far, only three confirmed systems have been identified in addition to a handful of candidates. We present the results of a multiwavelength study of the low-mass X-ray binary NGC 6652B in the globular cluster NGC 6652, including simultaneous radio and X-ray observations taken by the Karl G. Jansky Very Large Array and the Chandra X-ray Observatory, and optical spectroscopy and photometry. This source is the second brightest X-ray source in NGC 6652 ($L_{\textrm {X}}\sim 1.8 \times 10^{34}{\, \mathrm{erg\, s}^{-1}}$) and is known to be variable. We observe several X-ray flares over the duration of our X-ray observations, in addition to persistent radio emission and occasional radio flares. Simultaneous radio and X-ray data show no clear evidence of anticorrelated variability. Optical spectra of NGC 6652B indicate variable, broad H α emission that transitions from double-peaked emission to absorption over a time-scale of hours. We consider a variety of possible explanations for the source behaviour, and conclude that based on the radio and X-ray luminosities, short time-scale variability and X-ray flaring, and optical spectra, NGC 6652B is best explained as a transitional millisecond pulsar candidate that displays prolonged X-ray flaring behaviour. However, this could only be confirmed with observations of a change to the rotation-powered millisecond pulsar state.
On the Orbit of Exoplanet WASP-12b Campo, Christopher J; Harrington, Joseph; Hardy, Ryan A ...
The Astrophysical journal,
02/2011, Letnik:
727, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We observed two secondary eclipses of the exoplanet WASP-12b using the Infrared Array Camera on the Spitzer Space Telescope. The close proximity of WASP-12b to its G-type star results in extreme ...tidal forces capable of inducing apsidal precession with a period as short as a few decades. This precession would be measurable if the orbit had a significant eccentricity, leading to an estimate of the tidal Love number and an assessment of the degree of central concentration in the planetary interior. An initial ground-based secondary-eclipse phase reported by Lopez-Morales et al. (0.510 ? 0.002) implied eccentricity at the 4.5 Delta *s level. The spectroscopic orbit of Hebb et al. has eccentricity 0.049 ? 0.015, a 3 Delta *s result, implying an eclipse phase of 0.509 ? 0.007. However, there is a well-documented tendency of spectroscopic data to overestimate small eccentricities. Our eclipse phases are 0.5010 ? 0.0006 (3.6 and 5.8 Delta *mm) and 0.5006 ? 0.0007 (4.5 and 8.0 Delta *mm). An unlikely orbital precession scenario invoking an alignment of the orbit during the Spitzer observations could have explained this apparent discrepancy, but the final eclipse phase of Lopez-Morales et al. (0.510 ?+0.007 --0.006) is consistent with a circular orbit at better than 2 Delta *s. An orbit fit to all the available transit, eclipse, and radial-velocity data indicates precession at <1 Delta *s; a non-precessing solution fits better. We also comment on analysis and reporting for Spitzer exoplanet data in light of recent re-analyses.
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