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51.
Celine Clerkin Sinead Brennan Laura M. Mullaney 《Reports of Practical Oncology and Radiotherapy》2018,23(5):407-412
Aim
The aim of this research is to establish if variation exists in the dose delivered for head and neck (HN) localisation computed tomography (CT) imaging in radiation therapy (RT); to propose a national diagnostic reference levels (DRLs) for this procedure and to make a comparison between the national DRL and a DRL of a European sample.Background
CT has become an indispensable tool in radiotherapy (RT) treatment planning. It is a requirement of legislation in many countries that doses of ionising radiation for medical exposures be kept ‘As Low As Reasonably Achievable’. There are currently no dose guidelines for RT localisation CT of the HN.Materials and methods
All RT departments in Ireland and a sample of European departments were surveyed. Dose data on CT dose length product (DLP); dose index volume (CTDIvol); current time product; tube voltage and scan length was acquired for ten average-sized HN patients from each department. DRLs were proposed for DLP and CTDIvol using the rounded 75th percentile of the distribution of the means.Results
42% of Irish departments and one European department completed the survey. Significant variation was found in the mean DLP, CTDIvol and scan lengths across the Irish departments. The proposed Irish DRL is 882?mGy?cm and 21?mGy and the European department DRL is 816?mGy?cm and 21?mGy, for DLP and CTDIvol, respectively.Conclusions
Variation exists in doses used for HN RT localisation CT. DRLs have been proposed for comparison purposes with the aim of dose optimisation. 相似文献52.
Regulation of Spontaneous Activity of the δ-Opioid Receptor: Studies of Inverse Agonism in Intact Cells 总被引:1,自引:1,他引:0
Manolis Merkouris Ian Mullaney Zafiroula Georgoussi Graeme Milligan 《Journal of neurochemistry》1997,69(5):2115-2122
Abstract: Adenylyl cyclase activity was measured following labelling of the cellular ATP pool with [3 H]adenine in intact Rat-1 fibroblasts that had been stably transfected to express the murine δ-opioid receptor (clone D2). Basal [3 H]cyclic AMP accumulation was low and was increased substantially by the addition of the diterpene forskolin. The synthetic enkephalin d -Ala2 , d -Leu5 enkephalin (DADLE) produced strong inhibition of forskolin-amplified [3 H]cyclic AMP production, whereas the δ-opioid ligand ICI174864 augmented forskolin-amplified adenylyl cyclase activity. Naloxone was unable to mimic the effects of ICI174864, and coincubation of the cells with these two ligands attenuated the effect of ICI174864. The EC50 (9.4 ± 0.6 × 10−8 M ) for ICI174864 augmentation of forskolin-stimulated adenylyl cyclase was equal to its estimated K i . Pertussis toxin pretreatment of clone D2 cells prevented both this effect of ICI174864 and the inhibition produced by DADLE. Use of a Cytosensor microphysiometer demonstrated that treatment of clone D2 cells with DADLE increased and that with ICI174864 decreased the basal rate of cellular proton extrusion. By using these two distinct experimental strategies, ICI174864 was shown to function in a manner anticipated for an inverse agonist, demonstrating that such effects can be observed in intact cells and are not restricted to assays performed on membrane preparations. 相似文献
53.
High Resolution Mapping of Genetic Factors Affecting Abdominal Bristle Number in Drosophila Melanogaster 总被引:7,自引:4,他引:3
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A. D. Long S. L. Mullaney L. A. Reid J. D. Fry C. H. Langley TFC. Mackay 《Genetics》1995,139(3):1273-1291
Factors responsible for selection response for abdominal bristle number and correlated responses in sternopleural bristle number were mapped to the X and third chromosome of Drosophila melanogaster. Lines divergent for high and low abdominal bristle number were created by 25 generations of artificial selection from a large base population, with an intensity of 25 individuals of each sex selected from 100 individuals of each sex scored per generation. Isogenic chromosome substitution lines in which the high (H) X or third chromosome were placed in an isogenic low (L) background were derived from the selection lines and from the 93 recombinant isogenic (RI) HL X and 67 RI chromosome 3 lines constructed from them. Highly polymorphic neutral r00 transposable elements were hybridized in situ to the polytene chromosomes of the RI lines to create a set of cytogenetic markers. These techniques yielded a dense map with an average spacing of 4 cM between informative markers. Factors affecting bristle number, and relative viability of the chromosome 3 RI lines, were mapped using a multiple regression interval mapping approach, conditioning on all markers >/=10 cM from the tested interval. Two factors with large effects on abdominal bristle number were mapped on the X chromosome and five factors on the third chromosome. One factor with a large effect on sternopleural bristle number was mapped to the X and two were mapped to the third chromosome; all factors with sternopleural effects corresponded to those with effects on abdominal bristle number. Two of the chromosome 3 factors with large effects on abdominal bristle number were also associated with reduced viability. Significant sex-specific effects and epistatic interactions between mapped factors of the same order of magnitude as the additive effects were observed. All factors mapped to the approximate positions of likely candidate loci (ASC, bb, emc, h, mab, Dl and E(spl)), previously characterized by mutations with large effects on bristle number. 相似文献
54.
Philippe Vidon Diana L. Karwan A. Scott Andres Shreeram Inamdar Sujay Kaushal Jonathan Morrison John Mullaney Donald S. Ross Andrew W. Schroth James B. Shanley Byungman Yoon 《Biogeochemistry》2018,137(3):351-365
Although many climate predictions suggest that the frequency and intensity of large storm events might increase in the coming decades, few studies document the full impact of such events along their path. Here, we synthesize information on the impact of Hurricane Irene (formed August 21 2011) and Tropical Storm Lee (formed August 30, 2011) on erosion and sediment transport, lake metabolism, riparian hydrology and biogeochemistry, and stream water quality, from North Carolina to Maine. In almost all cases, these storms generated unprecedented changes in water quality (concentrations, loads), from tenfold increases in DOC and 100-fold increases in POC in Maryland, to 100-fold increases in TSS concentrations in Pennsylvania. Overbank flooding and up to 200-year streamflow events were recorded in New York and Vermont. In many cases, particulate loads (e.g. POC, PP, TSS) occurring during Irene and Lee represented more than 30% of the annual load. The dominance of particulate exports over solutes during Irene and Lee is consistent with the mobilization of normally immobile sediment pools, and massive erosion as reported at many locations across the Northeastern US. Several studies reported long lasting (> 1 year) effects of Irene and Lee on cyanobacterial blooms, erosion, or stream suspended sediment concentrations. However, this review also highlighted the lack of a consistent strategy in terms of methods, and measured water quality parameters. This strongly hinders our ability to fully assess the large-scale impact of such events on our environment, and ultimately their impact on our economy and society. 相似文献
55.
GTP- and inositol 1,4,5-trisphosphate-activated intracellular calcium movements in neuronal and smooth muscle cell lines 总被引:12,自引:0,他引:12
S H Chueh J M Mullaney T K Ghosh A L Zachary D L Gill 《The Journal of biological chemistry》1987,262(28):13857-13864
Recent evidence has revealed that a highly sensitive and specific guanine nucleotide regulatory process controls intracellular Ca2+ release within N1E-115 neuroblastoma cells (Gill, D. L., Ueda, T., Chueh, S. H., and Noel, M. W. (1986) Nature 320, 461-464). The present report documents GTP-induced Ca2+ release within quite distinct cell types, including the DDT1MF-2 smooth muscle cell line. GTP-induced Ca2+ release has similar GTP sensitivity and specificity among cells and rapidly mobilizes up to 70% of Ca2+ specifically accumulated within a nonmitochondrial Ca2+-pumping organelle within permeabilized DDT2MF-2 cells. Maximal GTP-induced release of Ca2+ is observed to be greater than inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release (the latter being approximately 30% of total releasable Ca2+). After maximal IP3-induced release, further IP3 addition is ineffective, whereas subsequent addition of GTP further releases Ca2+ to equal exactly the extent of Ca2+ release observed by addition of GTP in the absence of IP3. This suggests that IP3 releases Ca2+ from the same pool as GTP, whereas GTP also releases from an additional pool. The effects of GTP appear to be reversible since simple washing of GTP-treated cells restores their previous Ca2+ uptake properties. Electron microscopic analysis of GTP-treated membrane vesicles reveals their morphology to be unchanged, whereas treatment of vesicles with 3% polyethylene glycol, known to enhance GTP-mediated Ca2+ release, clearly induces close coalescence of membranes. In the presence of 4 mM oxalate, GTP induces a rapid and profound uptake, as opposed to release, of Ca2+. The findings suggest that GTP-activated Ca2+ movement is a widespread phenomenon among cells, which can function on the same Ca2+ pool mobilized by IP3, and although activating Ca2+ movement by a mechanism distinct from IP3, does so via a process that does not appear to involve fusion between membranes. 相似文献
56.
The potential role of transforming growth factor-alpha (TGF-alpha) as a mediator of cell-cell interactions in the growth and development of the testis was examined. Developing rat testes were collected, and preparations of mesenchymal-derived peritubular cells and epithelial-like Sertoli cells were isolated from prepubertal, midpubertal, and late pubertal rat testes. The developmental expression of TGF-alpha and its receptor, the epidermal growth factor receptor (EGFR), in whole testis and isolated cell types was determined using a nuclease protection assay. TGF-alpha and EGFR gene expression were predominant early in testis development and decreased during pubertal development. TGF-alpha expression was greatest in prepubertal peritubular cells. Sertoli cell TGF-alpha expression remained relatively constant during development, with a slight decline at the later pubertal stages. EGFR gene expression was predominant in peritublar cells throughout development. A low level of EGFR expression was detected in Sertoli cells. Scatchard analysis confirmed the presence of high affinity receptors on peritubular cells; however, no functional receptors were detected on Sertoli cells from any stage of development examined. Interestingly, low-level EGFR gene expression was also detected in pachytene spermatocytes and round spermatids. TGF-alpha was found to stimulate [3H] thymidine incorporation into DNA and increase cellular proliferation of peritubular cells from each developmental stage, while having no effect on Sertoli cells. The in vivo physiological significance of TGF-alpha was evaluated in a line of transgenic mice which overexpress TGF-alpha in the mature testis. These transgenic animals had no abnormal testicular morphology or alterations in spermatogenesis. Observations demonstrate that gene expression of TGF-alpha and its receptor is high during early pubertal stages when somatic cell growth is predominant and low at late pubertal stages when somatic cell proliferation is reduced. TGF-alpha can act as an autocrine/paracrine mitogen for the mesenchymal-derived peritubular cell, while actions on the Sertoli cell population are not evident. The observation that spermatogenic cells express the EGFR gene, although the protein remains to be identified, implies that TGF-alpha may potentially mediate Sertoli-germinal cell interactions. 相似文献
57.
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59.
The Volta River delta developed as an asymmetric lobe in a tectonic offset on the coast of Ghana. The delta comprises a large curvilinear spit that widens in its central portion due to the adjunction of successive sandy beach ridges. The appearance of a distinct spit, in lieu of a continuous barrier from the present mouth of the Volta River to the Bight of Benin coast, may be an outgrowth of a natural change in the location of the mouth of the Volta. The spit marks a segmentation of the unique sand drift cell that hitherto prevailed on this bight coast. Spit growth has been accompanied by a wave of erosion over the last century of the immediate downdrift sector of the bight coast, endangering the town of Keta. Erosion since the 1960s may have been aggravated by the construction of the Akosombo hydropower dam. The tip of the spit has recently welded to the shoreline, thus assuring resumption of sand supply from the Volta towards the rest of this formerly sand-starved sector of the bight coast. Blocking of sediment by the Akosombo Dam is, in due course, likely to become the overarching factor in delta shoreline stability. 相似文献
60.
Recent work has questioned whether the negativity bias is a distinct component of affective picture processing. The current study was designed to determine whether there are different neural correlates of processing positive and negative pictures using event-related brain potentials. The early posterior negativity and late positive potential were greatest in amplitude for erotic pictures. Partial Least Squares analysis revealed one latent variable that distinguished erotic pictures from neutral and positive pictures and another that differentiated negative pictures from neutral and positive pictures. The effects of orienting task on the neural correlates of processing negative and erotic pictures indicate that affective picture processing is sensitive to both stimulus-driven, and attentional or decision processes. The current data, together with other recent findings from our laboratory, lead to the suggestion that there are distinct neural correlates of processing negative and positive stimuli during affective picture processing. 相似文献