Abstract
Dwarf galaxies are thought to host the remnants of the early Universe seed black holes (BHs) and to be dominated by supernova feedback. However, recent studies suggest that BH feedback could ...also strongly impact their growth. We report the discovery of 35 dwarf galaxies hosting radio active galactic nucleus (AGN) out to redshift ∼3.4, which constitutes the highest redshift sample of AGNs in dwarf galaxies. The galaxies are drawn from the VLA-COSMOS 3 GHz Large Project and all are star forming. After removing the contribution from star formation to the radio emission, we find a range of AGN radio luminosities of $L^\mathrm{AGN}_\mathrm{1.4\, GHz} \sim 10^{37}$–1040 erg s−1. The bolometric luminosities derived from the fit of their spectral energy distribution are ≳1042 erg s−1, in agreement with the presence of AGNs in these dwarf galaxies. The 3 GHz radio emission of most of the sources is compact and the jet powers range from Qjet ∼ 1042 to 1044 erg s−1. These values, as well as the finding of jet efficiencies ≥10 per cent in more than 50 per cent of the sample, indicate that dwarf galaxies can host radio jets as powerful as those of massive radio galaxies whose jet mechanical feedback can strongly affect the formation of stars in the host galaxy. We conclude that AGN feedback can also have a very strong impact on dwarf galaxies, either triggering or hampering star formation and possibly the material available for BH growth. This implies that those low-mass AGNs hosted in dwarf galaxies might not be the untouched relics of the early seed BHs, which has important implications for seed BH formation models.
The impact of chronic exposure to fine particulate matter (particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5)) on respiratory disease and lung cancer mortality is ...poorly understood. In a cohort of 18.9 million Medicare beneficiaries (4.2 million deaths) living across the conterminous United States between 2000 and 2008, we examined the association between chronic PM2.5 exposure and cause-specific mortality. We evaluated confounding through adjustment for neighborhood behavioral covariates and decomposition of PM2.5 into 2 spatiotemporal scales. We found significantly positive associations of 12-month moving average PM2.5 exposures (per 10-μg/m3 increase) with respiratory, chronic obstructive pulmonary disease, and pneumonia mortality, with risk ratios ranging from 1.10 to 1.24. We also found significant PM2.5-associated elevated risks for cardiovascular and lung cancer mortality. Risk ratios generally increased with longer moving averages; for example, an elevation in 60-month moving average PM2.5 exposures was linked to 1.33 times the lung cancer mortality risk (95% confidence interval: 1.24, 1.40), as compared with 1.13 (95% confidence interval: 1.11, 1.15) for 12-month moving average exposures. Observed associations were robust in multivariable models, although evidence of unmeasured confounding remained. In this large cohort of US elderly, we provide important new evidence that long-term PM2.5 exposure is significantly related to increased mortality from respiratory disease, lung cancer, and cardiovascular disease.
We present a sample of 40 active galactic nucleus (AGN) in dwarf galaxies at redshifts z ≲ 2.4. The galaxies are drawn from the Chandra COSMOS-Legacy survey as having stellar masses 107 ≤ M* ≤ 3 × ...109 M⊙. Most of the dwarf galaxies are star forming. After removing the contribution from star formation to the X-ray emission, the AGN luminosities of the 40 dwarf galaxies are in the range L0.5-10 keV ∼ 1039-1044 erg s-1. With 12 sources at z > 0.5, our sample constitutes the highest-redshift discovery of AGN in dwarf galaxies. The record-holder is cid_1192, at z = 2.39 and with L0.5-10 keV ∼ 1044 erg s-1. One of the dwarf galaxies has M* = 6.6 × 107 M⊙ and is the least massive galaxy found so far to host an AGN. All the AGN are of type 2 and consistent with hosting intermediate-mass black holes (BHs) with masses ∼104-105 M⊙ and typical Eddington ratios >1 per cent. We also study the evolution, corrected for completeness, of AGN fraction with stellar mass, X-ray luminosity, and redshift in dwarf galaxies out to z = 0.7. We find that the AGN fraction for 109 < M* ≤ 3 × 109 M⊙ and LX ∼ 1041-1042 erg s-1 is ∼0.4 per cent for z ≤ 0.3 and that it decreases with X-ray luminosity and decreasing stellar mass. Unlike massive galaxies, the AGN fraction seems to decrease with redshift, suggesting that AGN in dwarf galaxies evolve differently than those in high-mass galaxies. Mindful of potential caveats, the results seem to favour a direct collapse formation mechanism for the seed BHs in the early Universe.
Brain metastases are a very common manifestation of cancer that have historically been approached as a single disease entity given the uniform association with poor clinical outcomes. Fortunately, ...our understanding of the biology and molecular underpinnings of brain metastases has greatly improved, resulting in more sophisticated prognostic models and multiple patient-related and disease-specific treatment paradigms. In addition, the therapeutic armamentarium has expanded from whole-brain radiotherapy and surgery to include stereotactic radiosurgery, targeted therapies and immunotherapies, which are often used sequentially or in combination. Advances in neuroimaging have provided additional opportunities to accurately screen for intracranial disease at initial cancer diagnosis, target intracranial lesions with precision during treatment and help differentiate the effects of treatment from disease progression by incorporating functional imaging. Given the numerous available treatment options for patients with brain metastases, a multidisciplinary approach is strongly recommended to personalize the treatment of each patient in an effort to improve the therapeutic ratio. Given the ongoing controversies regarding the optimal sequencing of the available and expanding treatment options for patients with brain metastases, enrolment in clinical trials is essential to advance our understanding of this complex and common disease. In this Review, we describe the key features of diagnosis, risk stratification and modern paradigms in the treatment and management of patients with brain metastases and provide speculation on future research directions.
An inexpensive ultrasonic generator (household humidifier; ultrasonic spray pyrolysis) is used to synthesize porous, hollow, and ball‐in‐ball metal oxide microspheres (see figure). The morphology and ...pore size were controlled by the silica to TiIV ratio and silica particle size. With the introduction of transition‐metal ions, core/shell‐type microspheres can be synthesized in a single‐pot synthesis. These nanomaterials are rapidly taken up into the cytoplasm (but not into the nucleus) of macrophages and show very little cell toxicity.
Abstract
We present a catalog of 10,718 objects in the COSMOS field, observed through multi-slit spectroscopy with the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope in the ...wavelength range ∼5500–9800 Å. The catalog contains 6617 objects with high-quality spectra (two or more spectral features), and 1798 objects with a single spectroscopic feature confirmed by the photometric redshift. For 2024 typically faint objects, we could not obtain reliable redshifts. The objects have been selected from a variety of input catalogs based on multi-wavelength observations in the field, and thus have a diverse selection function, which enables the study of the diversity in the galaxy population. The magnitude distribution of our objects is peaked at
I
AB
∼ 23 and
K
AB
∼ 21, with a secondary peak at
K
AB
∼ 24. We sample a broad redshift distribution in the range 0 <
z
< 6, with one peak at
z
∼ 1, and another one around
z
∼ 4. We have identified 13 redshift spikes at
z
> 0.65 with chance probabilities < 4 × 10
−4
, some of which are clearly related to protocluster structures of sizes >10 Mpc. An object-to-object comparison with a multitude of other spectroscopic samples in the same field shows that our DEIMOS sample is among the best in terms of fraction of spectroscopic failures and relative redshift accuracy. We have determined the fraction of spectroscopic blends to about 0.8% in our sample. This is likely a lower limit and at any rate well below the most pessimistic expectations. Interestingly, we find evidence for strong lensing of Ly
α
background emitters within the slits of 12 of our target galaxies, increasing their apparent density by about a factor of 4.
Ultrasound has become widely accepted as the first imaging technique used for the assessment of cervical lymph node metastasis in patients with papillary thyroid cancer. In this systematic review and ...meta-analysis, we evaluate the performance of CT for the preoperative diagnosis of cervical lymph node metastasis in patients with papillary thyroid cancer compared with ultrasound.
Ovid-MEDLINE and EMBASE data bases were searched for studies regarding the use of CT to diagnose cervical lymph node metastasis. The diagnostic performance of CT, ultrasound, and combined CT/ultrasound was assessed by using level-by-level and patient-based analyses. We also performed meta-analyses on the basis of the central and lateral neck levels.
Nine eligible studies, including a total sample size of 1691 patients, were included. CT showed a summary sensitivity of 62% (95% CI, 52%-70%) and specificity of 87% (95% CI, 80%-92%) for diagnosing cervical lymph node metastasis when using level-by-level analysis. There was a positive correlation between the sensitivity and the false-positive rate (correlation coefficient, 0.807) because of the threshold effect. The summary sensitivity of combined CT/ultrasound (69%; 95% CI, 61%-77%) was significantly higher than ultrasound (51%; 95% CI, 42%-60%), though the summary specificity did not differ.
The diagnostic performances of CT and ultrasound are similar, though CT and ultrasound combined are superior to ultrasound only. CT may be used as a complementary diagnostic method in addition to ultrasound for diagnosing cervical lymph node metastasis in patients with papillary thyroid cancer.
Summary
Background
Abnormal deposition of melanin may cause an aesthetic skin problem; therefore, the control of unwanted excessive melanin synthesis is the major goal of cosmetic research.
...Objectives
To identify novel tyrosinase (TYR) inhibitors from marine plants and examine their cellular antimelanogenic effects.
Methods
The extracts of 50 marine plants endemic to Korea were screened against human TYR. Active constituents were then isolated from the selected plant extracts that showed potential and their chemical structures elucidated. Furthermore, their antimelanogenic effects were examined using murine melanoma B16/F10 cells and human epidermal melanocytes (HEM).
Results
Among the tested extracts, that of Phyllospadix iwatensis Makino exhibited the strongest human TYR inhibitory activity. The active constituents were purified from the butanol fraction of the P. iwatensis extract and identified as hispidulin 7‐sulfate and luteolin 7‐sulfate. Luteolin 7‐sulfate inhibited human TYR more strongly than hispidulin 7‐sulfate, luteolin, hispidulin and arbutin. Furthermore, luteolin 7‐sulfate showed lower cytotoxicity than luteolin in both B16/F10 cells and HEM. Luteolin 7‐sulfate attenuated cellular melanin synthesis more effectively in B16/F10 cells and HEM stimulated by α‐melanocyte‐stimulating hormone and l‐tyrosine than arbutin.
Conclusions
This study demonstrates that luteolin 7‐sulfate isolated from P. iwatensis is a human TYR inhibitor with advantageous antimelanogenic properties, and would be useful for development as a therapeutic agent for the control of unwanted skin pigmentation.
What's already known about this topic?
Previous efforts to develop antimelanogenic agents have investigated the activity of various plants against mushroom tyrosinase. However, this approach is not appropriate because of the inherent differences between mushroom and human tyrosinases.
What does this study add?
This study screened 50 marine plants for human tyrosinase inhibitory effects and found that Phyllospadix iwatensis extract and its constituent, luteolin 7‐sulfate, inhibited human tyrosinase activity and attenuated melanin synthesis in B16/F10 cells and human epidermal melanocytes.
What is the translational message?
Marine plants have attracted attention as under‐researched resources for bioactive compounds, and this study demonstrates that luteolin 7‐sulfate isolated from Phyllospadix iwatensis Makino, a kind of seagrass, is a more potent and safer inhibitor of cellular melanin synthesis than luteolin.
If these findings are confirmed by clinical studies, the flavonoid sulfate may be useful for the control of unwanted skin pigmentation due to excessive melanin synthesis.
Linked Comment: Khotimchenko. Br J Dermatol 2016; 175:457–458.
Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne ...pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recent studies have considered effects from exposure to ambient air pollutants.
To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss.
We identified and reviewed relevant articles from 1950 to 2015 using PubMed and Web of Science and focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function.
We identified and reviewed 17 articles, with 1 additional article added from a bibliography search, for a total of 18 human studies. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology or inducing local inflammation and cellular stress responses.
Ambient air pollution may impact human olfactory function. Additional studies are needed to examine air pollution-related olfactory impacts on the general population using measured pollution exposures and to link pollution exposure with olfactory dysfunction and related pathology. Citation: Ajmani GS, Suh HH, Pinto JM. 2016. Effects of ambient air pollution exposure on olfaction: a review. Environ Health Perspect 124:1683-1693; http://dx.doi.org/10.1289/EHP136.
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