1,579 research outputs found

    Expression patterns of chondrocyte genes cloned by differential display in tibial dyschondroplasia

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    AbstractTibial dyschondroplasia (TD) appears to involve a failure of the growth plate chondrocytes within growing long bones to differentiate fully to the hypertrophic stage, resulting in a mass of prehypertrophic chondrocytes which form the avascular TD lesion. Many biochemical and molecular markers of chondrocyte hypertrophy are absent from the lesion, or show reduced expression, but the cause of the disorder remains to be identified. As differentiation to the hypertrophic state is impaired in TD, we hypothesised that chondrocyte genes that are differentially expressed in the growth plate should show altered expression in TD. Using differential display, four genes, B-cadherin, EF2, HT7 and Ex-FABP were cloned from chondrocytes stimulated to differentiate to the hypertrophic stage in vitro, and their differential expression confirmed in vivo. Using semi-quantitative RT-PCR, the expression patterns of these genes were compared in chondrocytes from normal and TD growth plates. Surprisingly, none of these genes showed the pattern of expression that might be expected in TD lesion chondrocytes, and two of them, B-cadherin and Ex-FABP, were upregulated in the lesion. This indicates that the TD phenotype does not merely reflect the absence of hypertrophic marker genes, but may be influenced by more complex developmental mechanisms/defects than previously thought

    Animal diets in the Waterberg based on stable isotopic composition of faeces

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    Faecal analysis of diet in free-ranging mammals can provide insight into local habitat conditions by reflecting the resources actually utilized. Here we used stable light isotope analysis of faeces to qualify, as well as quantify, certain aspects of mammal food selection in a recovering, nutrient-poor, savanna habitat in the Waterberg. Stable carbon isotope ratios in faeces reflect proportions of C3-foods (browse) to C4-foods (grass) consumed, whereas stable nitrogen isotope ratios reflect a combination of trophic behaviour, protein intake, and water and nutritional stress. Percentage nitrogen indicates the nutritional quality of the diet, at least in terms of crude protein intake. We used these data to reconstruct and compare the diets of various mammal species from two reserves in the Waterberg: the Welgevonden Private Game Reserve and Zoetfontein Private Game Farm

    Accuracy of Ultrasonography-Guided Fine-Needle Aspiration in Detecting Persistent Nodal Disease After Chemoradiotherapy

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    IMPORTANCE: Few patients with persistent adenopathy following chemoradiotherapy (CRT) for head and neck squamous cell carcinoma harbor viable disease. Improved selectivity for surgical salvage is needed to prevent unnecessary salvage neck dissection. OBJECTIVE: To determine whether ultrasonography-guided fine-needle aspiration (FNA) can be used to identify viable cancer cells in the lymph nodes of patients with persistent radiographic adenopathy following CRT. DESIGN, SETTING, AND PARTICIPANTS: A pilot study included patients undergoing preoperative ultrasonography-guided FNA of lymph nodes considered suspicious on radiography prior to planned neck dissection at a quaternary care facility from February 28, 2011, to March 18, 2013. Data analysis was performed from April 28 to December 24, 2013. Patients treated for head and neck squamous cell carcinoma with CRT who were determined to have persistent neck disease on a 6-week posttreatment computed tomographic scan of the neck and scheduled for salvage neck dissection were considered candidates for this pilot study. All patients enrolled in the study underwent ultrasonography-guided FNA of the suspicious lymph nodes within 2 weeks of the planned neck dissection. The cytopathologist reading the samples was blinded to the patient's identity. EXPOSURES: Fine-needle aspiration with a 23- to 25-gauge needle following CRT. MAIN OUTCOMES AND MEASURES: The accuracy of ultrasonography-guided FNA cytologic results was compared with the standard of surgical pathologic examination of neck dissection specimens. RESULTS: Fourteen patients (11 [79%] men; mean [SD] age, 57.8 [11.2] years) were enrolled in this pilot study; data were collected on 17 lymph nodes. Among these 14 patients with incomplete radiographic clinical response, 17 lymph node aspirations were performed. Ultrasonography-guided FNA identified squamous cell carcinoma in the aspirates of 4 (80%) of the 5 nodes with squamous cell carcinoma identified on pathologic testing and confirmed the absence of disease in the remaining 12 (71%) lymph nodes. The statistical analysis of these results revealed a sensitivity of 80%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 92.3%. The diagnostic accuracy of ultrasonography-guided FNA at detecting residual persistent cancer was 88%. CONCLUSIONS AND RELEVANCE: This pilot study suggests that ultrasonography-guided FNA may be a feasible ancillary diagnostic imaging tool to imaging to assess patients with radiographic persistent disease prior to consideration of salvage neck dissection

    The ALMaQUEST survey ā€“ III. Scatter in the resolved star-forming main sequence is primarily due to variations in star formation efficiency

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    Using a sample of 11,478 spaxels in 34 galaxies with molecular gas, star formation and stellar maps taken from the ALMA-MaNGA QUEnching and STar formation (ALMaQUEST) survey, we investigate the parameters that correlate with variations in star formation rates on kpc scales. We use a combination of correlation statistics and an artificial neural network to quantify the parameters that drive both the absolute star formation rate surface density (Sigma_SFR), as well as its scatter around the resolved star forming main sequence (Delta Sigma_SFR). We find that Sigma_SFR is primarily regulated by molecular gas surface density (Sigma_H2) with a secondary dependence on stellar mass surface density (Sigma_*), as expected from an `extended Kennicutt-Schmidt relation'. However, Delta Sigma_SFR is driven primarily by changes in star formation efficiency (SFE), with variations in gas fraction playing a secondary role. Taken together, our results demonstrate that whilst the absolute rate of star formation is primarily set by the amount of molecular gas, the variation of star formation rate above and below the resolved star forming main sequence (on kpc scales) is primarily due to changes in SFE

    Institutional management of greenhouse gas emissions: How much does 'green' reputation matter?

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    Climate Change, green reputation, conjoint analysis, Environmental Economics and Policy, Resource /Energy Economics and Policy, Q29, Q40, Q51,

    National Geodetic Satellite Program, Part II: Smithsonian Astrophysical Observatory

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    A sequence of advances in the determination of geodetic parameters presented by the Smithsonian Astrophysical Observatory are described. A Baker-Nunn photographic system was used in addition to a ruby-laser ranging system to obtain data for refinement of geodetic parameters. A summary of the data employed to: (1) derive coordinates for the locations of various tracking stations; and (2) determine the gravitational potential of the earth, is presented

    Endoscopic Resection of Sinonasal Malignancy: A Systematic Review and Meta-analysis

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    OBJECTIVES: The use of endoscopic approaches for sinonasal malignancy resection has increased, but survival data are limited secondary to disease rarity and new surgical technique. Here we present a systematic review and meta-analysis of endoscopic endonasal resection of sinonasal malignancy. DATA SOURCES: MEDLINE, PubMed Central, NCBI Bookshelf, Cochrane Library, clinicaltrials.gov, National Guideline Clearinghouse. REVIEW METHODS: PRISMA/MOOSE guidelines were followed. MeSH terms were "endoscopic" AND ("esthesioneuroblastoma" OR "sinonasal adenocarcinoma" OR "squamous cell carcinoma" OR "sinonasal undifferentiated carcinoma"). For studies in which individual-level data were available, results were obtained by direct pooling. For studies in which only summary Kaplan-Meier curves were available, numerical data were extracted, traced, and aggregated by fitting a Weibull model. RESULTS: Of 320 studies identified, 35 case series were included (n = 952 patients), with 15 studies analyzed via aggregate modeling and 20 studies analyzed via direct pooling. Two- and 5-year survival rates for patients in aggregate modeling were 87.5% and 72.3%, respectively (mean follow-up: 32.9 months). Two- and 5-year survival for patients in direct pooling were 85.8% and 83.5%, respectively (mean follow-up: 43.0 Ā± 19.5 months). Significant overall survival difference was found between low- and high-grade cancers (P = .015) but not between low- and high-stage cancers (P = .79). CONCLUSION: Overall 2- and 5-year survival rates are comparable and sometimes greater than those from open craniofacial resection. Survival rates significantly differ by cancer grade but not stage. Journals and investigators should be encouraged to publish retrospective and prospective case series with staged survival updates based on established guidelines

    The quenching of galaxies, bulges, and disks since cosmic noon: A machine learning approach for identifying causality in astronomical data

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    We present an analysis of the quenching of star formation in galaxies, bulges, and disks throughout the bulk of cosmic history, from z=2āˆ’0z=2-0. We utilise observations from the SDSS and MaNGA at low redshifts. We complement these data with observations from CANDELS at high redshifts. Additionally, we compare the observations to detailed predictions from the LGalaxies semi-analytic model. To analyse the data, we developed a machine learning approach utilising a Random Forest classifier. We first demonstrate that this technique is extremely effective at extracting causal insight from highly complex and inter-correlated model data, before applying it to various observational surveys. Our primary observational results are as follows: At all redshifts studied in this work, we find bulge mass to be the most predictive parameter of quenching, out of the photometric parameter set (incorporating bulge mass, disk mass, total stellar mass, and B/TB/T structure). Moreover, we also find bulge mass to be the most predictive parameter of quenching in both bulge and disk structures, treated separately. Hence, intrinsic galaxy quenching must be due to a stable mechanism operating over cosmic time, and the same quenching mechanism must be effective in both bulge and disk regions. Despite the success of bulge mass in predicting quenching, we find that central velocity dispersion is even more predictive (when available in spectroscopic data sets). In comparison to the LGalaxies model, we find that all of these observational results may be consistently explained through quenching via preventative `radio-mode' active galactic nucleus (AGN) feedback. Furthermore, many alternative quenching mechanisms (including virial shocks, supernova feedback, and morphological stabilisation) are found to be inconsistent with our observational results and those from the literature

    Rumen physiology constrains diet niche: linking digestive physiology and food selection across wild ruminant species

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    We propose a hypothesis for digestive constraints on the browsing and grazing options available to ruminants: that the diet-niche range (maximum and minimum grass intake) of a species is dependent upon its predisposition to stratified rumen contents, based on observations that this characteristic is a critical step towards enhanced fibre digestion and greater fluid throughput. We compare a physiological (heterogeneity of ingesta fluid content) and an anatomical (the intraruminal papillation pattern) measure with dietary evidence for a range of African and temperate species. Both measures are strongly related to the mean percentage of grass in speciesā€™ natural diets, as well as to the maximum and minimum levels of grass intake, respectively. The nature of these effects implies a stratification-level threshold, below which a species will not use a grass-based diet, but above which grass consumption can increase exponentially. However, above this threshold, a minimum percentage of grass in the diet is a prerequisite for optimal performance. We argue that this second constraint is crucial, as it depicts how a greater fluid throughput reduces potential for detoxification of plant secondary compounds, and therefore limits the maximum amount of browse a stratifying species will consume
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