527 research outputs found
Prospectus, December 7, 1988
https://spark.parkland.edu/prospectus_1988/1031/thumbnail.jp
Altered Forebrain and Hindbrain Development in Mice Mutant for theGsh-2Homeobox Gene
AbstractThe patterning of the mammalian brain is orchestrated by a large battery of regulatory genes. Here we examine the developmental function of theGsh-2nonclustered homeobox gene. Whole-mount and serial sectionin situhybridizations have been used to better defineGsh-2expression domains within the developing forebrain, midbrain, and hindbrain.Gsh-2transcripts are shown to be particularly abundant in the hindbrain and within the developing ganglionic eminences of the forebrain. In addition, mice carrying a targeted mutation ofGsh-2have been generated and characterized. Homozygous mutants uniformly failed to survive more than 1 day following birth. At the physiologic level the mutants experienced apnea and reduced levels of hemoglobin oxygenation. Histologically, the mutant brains had striking alterations of discrete components. In the forebrain the lateral ganglionic eminence was reduced in size. In the hindbrain, the area postrema, an important cardiorespiratory chemosensory center, was absent. The contiguous nucleus tractus solitarius, involved in integrating sensory input to maintain homeostasis, was also severely malformed in mutants. Immunohistochemistry was used to examine the mutant brains for alterations in the distribution of markers specific for serotonergic and cholinergic neurons. In addition,in situhybridizations were used to define expression patterns of the Dlx 2 and Nkx 2.1 homeobox genes in Gsh-2 mutant mice. The mutant lateral ganglionic eminences showed an abnormal absence of Dlx 2 expression. These results better define the genetic program of development of the mammalian brain, support neuromeric models of brain development, and further suggest similar patterning function for homeobox genes in phylogenetically diverse organisms
Feasibility of intensity-modulated and image-guided radiotherapy for functional organ preservation in locally advanced laryngeal cancer
Purpose: The study aims to assess the feasibility of intensity-modulated and image-guided radiotherapy (IMRT, and IGRT, respectively) for functional preservation in locally advanced laryngeal cancer. A retrospective review of 27 patients undergoing concurrent chemoradiation for locally advanced laryngeal cancers (8 IMRT, 19 IGRT) was undertaken. In addition to regular clinical examinations, all patients had PET imaging at 4 months and 10 months after radiotherapy, then yearly. Loco-regional control, speech quality and feeding-tube dependency were assessed during follow-up visits. Results: At a median follow-up of 20 months (range 6-57 months), four out of 27 patients (14.8%) developed local recurrence and underwent salvage total laryngectomy. One patient developed distant metastases following salvage surgery. Among the 23 patients who conserved their larynx with no sign of recurrence at last follow-up, 22 (95%) reported normal or near normal voice quality, allowing them to communicate adequately. Four patients (14.8%) had long-term tube feeding-dependency because of severe dysphagia (2 patients) and chronic aspiration (2 patients, with ensuing death from aspiration pneumonia in one patient). Conclusions and Clinical Relevance: Functional laryngeal preservation is feasible with IMRT and IGRT for locally advanced laryngeal cancer. However, dysphagia and aspiration remain serious complications, due most likely to high radiation dose delivery to the pharyngeal musculatures. © 2012 Nguyen et al
Prospectus, December 15, 1988
https://spark.parkland.edu/prospectus_1988/1032/thumbnail.jp
Imaging Cold Gas to 1 kpc Scales in High-Redshift Galaxies with the ngVLA
The next generation Very Large Array (ngVLA) will revolutionize our understanding of the distant Universe via the detection of cold molecular gas in the first galaxies. Its impact on studies of galaxy characterization via detailed gas dynamics will provide crucial insight on dominant physical drivers for star-formation in high redshift galaxies, including the exchange of gas from scales of the circumgalactic medium down to resolved clouds on mass scales of ̃105 M☉. In this study, we employ a series of high-resolution, cosmological, hydrodynamic zoom simulations from the MUFASA simulation suite and a CASA simulator to generate mock ngVLA observations of a z ̃ 4.5 gas-rich star-forming galaxy. Using the DESPOTIC radiative transfer code that encompasses simultaneous thermal, chemical, and statistical equilibrium in calculating the molecular and atomic level populations, we generate parallel mock observations of low-J to high-J transitions of CO from ALMA for comparison. We find that observations of CO(1-0) are especially important for tracing the systemic redshift of the galaxy and the total mass of the well-shielded molecular gas reservoir, while even CO(2-1) can predominantly trace denser gas regions distinct from CO(1-0). The factor of 100 times improvement in mapping speed for the ngVLA beyond the Jansky VLA and the proposed ALMA Band 1 will make these detailed, high-resolution imaging and kinematic studies of CO(1-0) routine at z ̃ 2-5
A Close Binary Star Resolved from Occultation by 87 Sylvia
The star BD+29 1748 was resolved to be a close binary from its occultation by
the asteroid 87 Sylvia on 2006 December 18 UT. Four telescopes were used to
observe this event at two sites separated by some 80 km apart. Two flux drops
were observed at one site, whereas only one flux drop was detected at the
other. From the long-term variation of Sylvia, we inferred the probable shape
of the shadow during the occultation, and this in turn constrains the binary
parameters: the two components of BD+29 1748 have a projected separation of
0.097" to 0.110" on the sky with a position angle 104 deg to 107 deg. The
asteroid was clearly resolved with a size scale ranging from 130 to 290 km, as
projected onto the occultation direction. No occultation was detected for
either of the two known moonlets of 87 Sylvia.Comment: 12 pages, 4 figures, 2 tables; submitted to the PAS
Feasibility of Tomotherapy-Based Image-Guided Radiotherapy for Locally Advanced Oropharyngeal Cancer
PURPOSE: The study aims to assess the feasibility of tomotherapy-based image-guided (IGRT) radiotherapy for locally advanced oropharyngeal cancer. A retrospective review of 33 patients undergoing concurrent chemoradiation for locally advanced oropharyngeal cancers was conducted. Radiotherapy planning, treatment toxicity and loco-regional control were assessed. RESULTS: At a median follow-up of 32 months (6-47 months), no patient developed loco-regional recurrence. Two patients (6%) developed distant metastases. Grade 3-4 acute toxicity was respectively 72% and 25% for mucositis and gastrointestinal toxicity. Two patients (6%) had long-term dependence on tube feedings. Dose-volume histogram demonstrated excellent target volume coverage and low radiation dose to the organs at risk for complications. CONCLUSIONS AND CLINICAL RELEVANCE: IGRT provides excellent loco-regional control but acute toxicity remains significant and needs to be addressed in future prospective trials. The feasibility of Tomotherapy to decrease radiation dose to the normal tissues merits further investigations
Feasibility of image-guided radiotherapy based on helical tomotherapy to reduce contralateral parotid dose in head and neck cancer
Background
To evaluate the feasibility of image-guided radiotherapy based on helical Tomotherapy to spare the contralateral parotid gland in head and neck cancer patients with unilateral or no neck node metastases.
Methods
A retrospective review of 52 patients undergoing radiotherapy for head and neck cancers with image guidance based on daily megavoltage CT imaging with helical tomotherapy was performed.
Results
Mean contralateral parotid dose and the volume of the contralateral parotid receiving 40 Gy or more were compared between radiotherapy plans with significant constraint (SC) of less than 20 Gy on parotid dose (23 patients) and the conventional constraint (CC) of 26 Gy (29 patients). All patients had PTV coverage of at least 95% to the contralateral elective neck nodes. Mean contralateral parotid dose was, respectively, 14.1 Gy and 24.7 Gy for the SC and CC plans (p < 0.0001). The volume of contralateral parotid receiving 40 Gy or more was respectively 5.3% and 18.2% (p < 0.0001)
Conclusion
Tomotherapy for head and neck cancer minimized radiotherapy dose to the contralateral parotid gland in patients undergoing elective node irradiation without sacrificing target coverage
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