We present spatially resolved analysis of a lensed galaxy, SDSS1958+5950 at z = 2.225, from the Cambridge Sloan Survey of Wide Arcs in the Sky. We use our new high-resolution imaging data to ...construct a robust lens model for the galaxy group at z = 0.214. We employ the updated lens model to combine the Integral Field Spectrographic observations on two highly distorted images of the lensed target. We adopt a forward-modelling approach to deconvolve the effects of point spread function from the combined source-plane reconstruction. The approach is adapted to the lens model magnification and enables a resolution of ∼170 pc in the galaxy-source plane. We propose an ongoing merger as the origin of the lensed system on the basis of its source-plane morphology, kinematics and rest-frame emission-line ratios. Using our novel technique of adaptive coadded source plane reconstruction, we are able to detect different components in the velocity gradient that were not seen in previous studies of this object, plausibly belonging to different components in the merging system.
O(6)-Methylguanine-DNA-methyltransferase (MGMT) is a unique protein, which both repairs O(6)-alkylguanine lesions stoichiometrically without a multi-enzymatic pathway and self-inactivates. It has ...recently been linked to the therapeutic success of alkylating agent chemotherapy, specifically temozolomide treatment. This drug affects the MGMT pathway to induce cell death in tumor tissue. Low levels of functional MGMT have been correlated with success of treatment, while high levels bring about failure of therapy. Expression of MGMT protein varies in normal and tumoral tissue. Furthermore, its epigenetic silencing due to promoter methylation has been linked to its lack of expression in many types of tumor, including gliomas. Great enthusiasm surrounds the utility of this protein in cancer treatment. Not only has there been success in manipulating MGMT levels to enhance alkylating agent therapy, but studies also suggest a possible role of MGMT in protecting hematopoietic cells from the myelosuppressive effects of high-dose chemotherapy. Innovative research into this protein will no doubt be rewarding. This review presents a summary of what is known about this unique protein, including its structure, function in its pathway, polymorphisms, expression in normal and tumoral tissue, relation to alkylating agent therapy, and possible future applications.
Abstract
BACKGROUND:
O-6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that counteracts chemotherapeutic cytotoxicity of alkylating agents such as temozolomide. Low levels of MGMT ...expression have been shown to correlate with longer survival in glioma patients treated with temozolomide. The same is true in pituitary adenomas.
OBJECTIVE:
We investigated the immunohistochemical expression of MGMT in a variety of corticotroph adenoma subtypes to determine the potential utility of temozolomide as a therapeutic agent.
METHODS:
The tumors consisted of 40 cases of adrenocorticotropin-secreting pituitary tumors in Cushing disease, 12 Crooke cell adenomas, and 7 subtype I silent corticotroph adenomas. Staining for MGMT was assessed by light microscopy; nuclear reactivity was estimated semiquantitatively as present in < 10%, 10% to 25%, 25% to 50%, 50% to 75%, and > 75% of cells.
RESULTS:
Immunoexpression showed no correlation with patient age, sex, tumor size, invasiveness, or recurrence in patients with Cushing disease. Among adrenocorticotropin-secreting adenomas associated with Cushing disease, most invasive (60%) and recurrent (86%) tumors showed low MGMT immunopositivity, defined as < 25%. Most (75%) Crooke cell adenomas exhibited an MGMT immunoreactivity of ⩽ 50%. All subtype I silent corticotroph adenomas showed < 10% MGMT staining.
CONCLUSION:
Our descriptive findings of low MGMT expression in adrenocorticotropin-producing pituitary adenomas, particularly aggressive tumors, suggest that they may be suitable candidates for temozolomide therapy.
This study was performed for the rapid identification of Mycobacterium tuberculosis complex and its resistance to rifampicin and isoniazid, directly from the sputum samples of pulmonary tuberculosis ...patients.
A commercially available genotype MTBDR plus assay was used for the identification and detection of mutations in Mycobacterial isolates. A total of 100 sputum samples of pulmonary tuberculosis patients were analyzed by using the genotype MTBDR plus assay. The MTBDR plus assay is designed to detect the mutations in the hotspot region of rpoB gene, katG and regulatory region of inhA gene.
The genotype MTBDR plus assay detected 22% multidrug resistant (MDR), 2% rifampicin (RMP) monoresistant and 1% isoniazid (INH) monoresistant isolates. In 22 MDR isolates, the codons most frequently involved in RMP-associated mutations were codon 531 (54.55%), 516 (31.82%) and 526 (13.63%), and 90.90% of MDR isolates showed KatG S315T mutations and 9.1% showed inhA C-15T mutations associated with INH resistance.
The new genotype MTBDR plus assay represents a rapid, reliable tool for the detection of MDR-TB, wherein results are obtained in 5 h allowing early and appropriate treatment, which is essential to cut the transmission path and reduce the spread of MDR-TB. The genotype MTBDR plus assay can readily be included in a routine laboratory work for the early diagnosis and control of MDR-TB.
ABSTRACT This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for ...obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Paper I. In this paper, we present both high-resolution radio continuum images for all of these sources and H i 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0 5 and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ∼three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H i 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral "window" (i.e., the percentage of H i 21 cm absorption-line detections could be as high as ∼90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H i detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H i absorption may well be present but is masked by the RFI. Future searches for highly redshifted H i and molecular absorption can easily find more distant CSOs among bright, "blank field" radio sources, but will be severely hampered by an inability to determine accurate spectroscopic redshifts due to their lack of rest-frame UV continuum.
Abstract
We analyze spectra of a gravitationally lensed galaxy, known as the Sunburst Arc, that is leaking ionizing photons, also known as the Lyman continuum (LyC). Magnification from gravitational ...lensing permits the galaxy to be spatially resolved into one region that leaks ionizing photons and several that do not. Rest-frame UV and optical spectra from Magellan target 10 different regions along the lensed Arc, including six multiple images of the LyC leaking region and four regions that do not show LyC emission. The rest-frame optical spectra of the ionizing photon emitting regions reveal a blueshifted (Δ
V
= 27 km s
−1
) broad emission component (FWHM = 327 km s
−1
), comprising 55% of the total O
iii
line flux, in addition to a narrow component (FWHM = 112 km s
−1
), suggesting the presence of strong highly ionized gas outflows. This is consistent with the high-velocity ionized outflow inferred from the rest-frame UV spectra. In contrast, the broad emission component is less prominent in the nonleaking regions, comprising ∼26% of total O
iii
line flux. The high-ionization absorption lines are prominent in both the leaker and the nonleaker, but the low-ionization absorption lines are very weak in the leaker, suggesting that the line-of-sight gas is highly ionized in the leaker. Analyses of stellar wind features reveal that the stellar population of the LyC leaking regions is considerably younger (∼3 Myr) than that of the nonleaking regions (∼12 Myr), emphasizing that stellar feedback from young stars may play an important role in ionizing photon escape.
We report an integral-field spectroscopic (IFS) observation of a gravitationally lensed spiral galaxy A1689B11 at redshift z = 2.54. It is the most ancient spiral galaxy discovered to date and the ...second kinematically confirmed spiral at . Thanks to gravitational lensing, this is also by far the deepest IFS observation with the highest spatial resolution (∼400 pc) on a spiral galaxy at a cosmic time when the Hubble sequence is about to emerge. After correcting for a lensing magnification of 7.2 0.8, this primitive spiral disk has an intrinsic star formation rate of 22 2 M yr−1, a stellar mass of M , and a half-light radius of , typical of a main-sequence star-forming galaxy at . However, the H kinematics show a surprisingly tranquil velocity field with an ordered rotation ( km s−1) and uniformly small velocity dispersions ( km s−1 and km s−1). The low gas velocity dispersion is similar to local spiral galaxies and is consistent with the classic density wave theory where spiral arms form in dynamically cold and thin disks. We speculate that A1689B11 belongs to a population of rare spiral galaxies at that mark the formation epoch of thin disks. Future observations with the James Webb Space Telescope will greatly increase the sample of these rare galaxies and unveil the earliest onset of spiral arms.
Abstract
We image the spatial extent of a cool galactic outflow with fine-structure Fe
ii
* emission and resonant Mg
ii
emission in a gravitationally lensed star-forming galaxy at
z
= 1.70347. The Fe
...ii
* and Mg
ii
(continuum-subtracted) emissions span out to radial distances of ∼14.33 and 26.5 kpc, respectively, with maximum spatial extents of ∼21 kpc for Fe
ii
* emission and ∼30 kpc for Mg
ii
emission. Mg
ii
emission is patchy and covers a total area of ∼184 kpc
2
, constraining the minimum area covered by the outflowing gas to be ∼13% of the total area. Mg
ii
emission is asymmetric and shows ∼21% more extended emission along the decl. direction. We constrain the covering fractions of the Fe
ii
* and Mg
ii
emission as a function of radial distance and characterize them with a power-law model. The Mg
ii
2803 emission line shows two kinematically distinct emission components and may correspond to two distinct shells of outflowing gas with a velocity separation of Δ
v
∼ 400 km s
−1
. By using multiple images with different magnifications of the galaxy in the image plane, we trace the Fe
ii
* and Mg
ii
emissions around three individual star-forming regions. In all cases, both the Fe
ii
* and Mg
ii
emissions are more spatially extended compared to the star-forming regions traced by the O
ii
emission. These findings provide robust constraints on the spatial extent of the outflowing gas and, combined with outflow velocity and column density measurements, will give stringent constraints on mass-outflow rates of the galaxy.
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