Fast, quantitative nucleoside protection under solvent-free conditions

Persilylation of nucleoside hydroxyls was effected in quantitative yields under solvent-free conditions using a ball mill. In addition, one-pot persilylation and acylation of cytidine was performed as an exemplar reaction demonstrating the utility of solvent-free approaches to nucleoside chemistry.

A fast method for fuzzy neural modeling and refinement

In the identification of complex dynamic systems using fuzzy neural networks, one of the main issues is the curse of dimensionality, which makes it difficult to retain a large number of system inputs or to consider a large number of fuzzy sets. Moreover, due to the correlations, not all possible network inputs or regression vectors in the network are necessary and adding them simply increases the model complexity and deteriorates the network generalisation performance. In this paper, the problem is solved by first proposing a fast algorithm for selection of network terms, and then introducing a refinement procedure to tackle the correlation issue. Simulation results show the efficacy of the method.

Fragmentation and plasmid strand breaks in pure and gold-doped DNA irradiated by beams of fast hydrogen atoms

The results of an investigation into the damage caused to dry plasmid DNA after irradiation by fast (keV) hydrogen atoms are presented. Agarose gel electrophoresis was used to assess single and double strand break yields as a function of dose in dry DNA samples deposited on a mica substrate. Damage levels were observed to increase with beam energy. Strand break yields demonstrated a considerable dependence on sample structure and the method of sample preparation. Additionally, the effect of high-Z nanoparticles on damage levels was investigated by irradiating DNA samples containing controlled amounts of gold nanoparticles. In contrast to previous (photonic) studies, no enhancement of strand break yields was observed with the particles showing a slight radioprotective effect. A model of DNA damage as a function of dose has been constructed in terms of the probability for the creation of single and double strand breaks, per unit ion flux. This model provides quantitative conclusions about the effects of both gold nanoparticles and the different buffers used in performing the assays and, in addition, infers the proportion of multiply damaged fragments.

High tech start-ups in University Science Park incubators: The relationship between the start-up’s lifecycle progression and use of the incubator’s resources

University Science Park incubators (USIs) have emerged as a means by which Government, academia and business can develop high technology business firms (spin out HTBFs) from initial conception through to becoming established small firms, which are ready to move beyond the Science Park confines. Although there is considerable literature on how USIs can be improved and developed there is a paucity of studies, which explore how lifecycle development within HTBFs in USIs can affect how they use the unique resources and opportunities of the USI. Moreover, there is a focus on single point in time studies, which do not adequately investigate the longitudinal dynamics of HTBF lifecycle development within USIs. Therefore, the aim of this paper is to explore the longitudinal use of the unique resources of the USI by HTBFs at different lifecycle stages. The research methodology involved 18 HTBFs within two separate USIs. A series of longitudinal interviews and focus groups were conducted with HTBFs and USI staff over a 36-month period. NUD*IST software was used in developing the coding and analysis of transcripts. The results show that a HTBF's propensity to make effective use of the USI's resources and support increases as the lifecycle stage of the company increases and the small-firm searches for independence and autonomy. Therefore, further research is required to investigate the following two outstanding questions; firstly, which usage pattern is associated with the HTBF's ultimate success or failure in the marketplace? And secondly, are there any services missing from the observed array that the USI could provide to enhance the HTBF's degree of ultimate success? © 2007 Elsevier Ltd. All rights reserved.

The Yin and Yang of vitamin D receptor (VDR) signaling in neoplastic progression: Operational networks and tissue-specific growth control

Substantive evidence implicates vitamin D receptor (VDR) or its natural ligand 1a,25-(OH)2 D3 in modulation of tumor growth. However, both human and animal studies indicate tissue-specificity of effect. Epidemiological studies show both inverse and direct relationships between serum 25(OH)D levels and common solid cancers. VDR ablation affects carcinogen-induced tumorigenesis in a tissue-specific manner in model systems. Better understanding of the tissue-specificity of vitamin D-dependent molecular networks may provide insight into selective growth control by the seco-steroid, 1a,25-(OH)2 D3. This commentary considers complex factors that may influence the cell- or tissue-specificity of 1a,25-(OH)2 D3/VDR growth effects, including local synthesis, metabolism and transport of vitamin D and its metabolites, vitamin D receptor (VDR) expression and ligand-interactions, 1a,25-(OH)2 D3 genomic and non-genomic actions, Ca2+ flux, kinase activation, VDR interactions with activating and inhibitory vitamin D responsive elements (VDREs) within target gene promoters, VDR coregulator recruitment and differential effects on key downstream growth regulatory genes. We highlight some differences of VDR growth control relevant to colonic, esophageal, prostate, pancreatic and other cancers and assess the potential for development of selective prevention or treatment strategies.