Early-response gene signalling is induced by angiogenic oligosaccharides of hyaluronan in endothelial cells. Inhibition by non-angiogenic, high-molecular-weight hyaluronan

K-ras gene sequences mutant at codon 12 were recovered following differential dot-blot hybridization of genomic DNA from human RSa cells up to 12 days after the cells had been irradiated with far-UV (principally 254 nm). By contrast, no mutant codon 12 sequences were recovered from cells which had been treated with 50 IU/ml human interferon (HuIFN)-alpha for 24 h prior to their UV exposure. HuIFN-alpha treatment in combination with anti-HuIFN-alpha antibody did not lead to the loss of mutant sequences. However, culture of interferon-pretreated cells with medium containing the protease inhibitor antipain (0.01 mM) for 6 h immediately after UV irradiation led to the recovery of mutant codon 12 sequences. Thus, while treatment with HuIFN-alpha appeared to prevent any UV-induced mutations affecting codon 12 of the K-ras gene from being recovered, the putative antipain-sensitive protease responsible for this suppressive affect appeared to be significantly affected by the protease inhibitor antipain.     

Receptor-like genes in the major resistance locus of lettuce are subject to divergent selection

Disease resistance genes in plants are often found in complex multigene families. The largest known cluster of disease resistance specificities in lettuce contains the RGC2 family of genes. We compared the sequences of nine full-length genomic copies of RGC2 representing the diversity in the cluster to determine the structure of genes within this family and to examine the evolution of its members. The transcribed regions range from at least 7.0 to 13.1 kb, and the cDNAs contain deduced open reading frames of approximately 5. 5 kb. The predicted RGC2 proteins contain a nucleotide binding site and irregular leucine-rich repeats (LRRs) that are characteristic of resistance genes cloned from other species. Unique features of the RGC2 gene products include a bipartite LRR region with >40 repeats. At least eight members of this family are transcribed. The level of sequence diversity between family members varied in different regions of the gene. The ratio of nonsynonymous (Ka) to synonymous (Ks) nucleotide substitutions was lowest in the region encoding the nucleotide binding site, which is the presumed effector domain of the protein. The LRR-encoding region showed an alternating pattern of conservation and hypervariability. This alternating pattern of variation was also found in all comparisons within families of resistance genes cloned from other species. The Ka /Ks ratios indicate that diversifying selection has resulted in increased variation at these codons. The patterns of variation support the predicted structure of LRR regions with solvent-exposed hypervariable residues that are potentially involved in binding pathogen-derived ligands.     

17 beta-estradiol hydroxylation catalyzed by human cytochrome P450 1B1

The 4-hydroxy metabolite of 17 beta-estradiol (E2) has been implicated in the carcinogenicity of this hormone. Previous studies showed that aryl hydrocarbon-receptor agonists induced a cytochrome P450 that catalyzed the 4-hydroxylation of E2. This activity was associated with human P450 1B1. To determine the relationship of the human P450 1B1 gene product and E2 4-hydroxylation, the protein was expressed in Saccharomyces cerevisiae. Microsomes from the transformed yeast catalyzed the 4- and 2-hydroxylation of E2 with Km values of 0.71 and 0.78 microM and turnover numbers of 1.39 and 0.27 nmol product min-1.nmol P450-1, respectively. Treatment of MCF-7 human breast cancer cells with the aryl hydrocarbon-receptor ligand indolo[3,2-b]carbazole resulted in a concentration-dependent increase in P450 1B1 and P450 1A1 mRNA levels, and caused increased rates of 2-, 4-, 6 alpha-, and 15 alpha-hydroxylation of E2. At an E2 concentration of 10 nM, the increased rates of 2- and 4-hydroxylation were approximately equal, emphasizing the significance of the low Km P450 1B1-component of E2 metabolism. These studies demonstrate that human P450 1B1 is a catalytically efficient E2 4-hydroxylase that is likely to participate in endocrine regulation and the toxicity of estrogens.     

Impacts of ice cover on local scour around semi-circular bridge abutment简

The presence of ice cover in winter can significantly change the flow field around bridge abutments, which can also cause a different local scour pattern. To investigate the impacts of ice cover, results from a recent flume experiments were presented. Smooth and rough ice covers were created to investigate the impacts of ice cover roughness on the scour geometry around the semi-circular abutment. Three bed materials were used, with 50D s of 0.58 mm, 0.50 mm, 0.47 mm respectively. Scour volume and scour area were calculated. It was found that the maximum scour depth was located 75o inclined to the flume wall. Under rough ice cover, the scour area and scour depth were the largest. An empirical equation on the maximum scour depth was also developed.     

Improving Window Manipulation and Content Interaction on High-Resolution,Wall-Sized Displays

Interaction with high-resolution wall-sized (Powerwall) displays can be a tedious and difficult task due to large display areas and small target sizes. To overcome this, we developed techniques that reduce the precision required to manipulate windows and select data. The manipulation layer speeds up the common tasks of moving and resizing application windows by overlaying them with large, transparent target areas. The Power-Lens magnifies target sizes by automatically appearing once the cursor reaches the region of interest. Two experiments evaluated these techniques against conventional desktop-style interfaces. Experiment 1 showed the window manipulation layer to speed up the tasks of moving and resizing a window by 24% and 27%, respectively. Experiment 2 showed the Power-Lens to speed up the selection of 5?×?5 pixel targets by 18%. Together, our new techniques help to make interaction more fluid on Powerwall displays.     

Towards a visual approach for component-based software development

The ever increasing emphasis on distributed systems has led to advances in the client/server model and the emergence of component-based software development as an important paradigm in software engineering. Along with the new computer technologies it is necessary to reuse legacy code. Approaches to application development over, for example, the Internet are important if this is to be successful. This paper examines these issues and argues that incorporating the ideas of the component-based approach and reuse can significantly assist the application software developer. It demonstrates an approach through the development of an interactive/visual environment for component-based assembly.     

The influence of growth hormone (rhGH) therapy on tooth formation in idiopathic short statured children

The purpose of this preliminary study was to evaluate tooth formation in children with idiopathic short stature, before and during treatment with recombinant growth hormone (rhGH). Twenty-nine short-statured children ages 6 to 13 years were assigned into two treatment groups, an "experimental" group (n = 18), which received rhGH, and a "control" group (n = 11), which was observed for 1 year before commencing rhGH treatment. Clinical and radiographic records were obtained at the initial, year 1, and year 2 visits. Tooth formation and stature were assessed by calculating Z-scores, appropriate for the age and gender of each child. Delta-Z scores, which measure the change in Z-score over time, were also calculated between annual visits. Height was measured and recorded every 3 months, and Z-score statural norms for age and gender were derived from the 1977 National Center for Health Services national probability sampling. Tooth formation standards were derived from Moorrees et al. A matched control sample for tooth development was derived from untreated children. Tooth formation was initially delayed although the degree of reduction in stature exceeded the initial degree of delay in tooth formation. During this 2-year study, rhGH therapy had a significant influence on acceleration or gain in stature, but did not have a significant influence on tooth formation.     

An image processing scheme to quantitatively extract and validate hyoid bone motion based on real-time ultrasound recordings of swallowing

An image processing technique with associated hardware was developed to quantitatively extract hyoid bone motion from realtime submandibular ultrasound images recorded during the swallowing act. Videofluorographic imaging, the "gold standard" of swallowing studies, was recorded simultaneously and synchronized to the ultrasound. Hyoid position obtained from the ultrasound was validated based on the videofluorography using personal computer-based image processing methods.