Affinity partitioning of plasmid DNA with a zinc finger protein

The affinity isolation of pre-purified plasmid DNA (pDNA) from model buffer solutions using native and poly(ethylene glycol) (PEG) derivatized zinc finger–GST (Glutathione-S-Transferase) fusion protein was examined in PEG–dextran (DEX) aqueous two-phase systems (ATPSs). In the absence of pDNA, partitioning of unbound PEGylated fusion protein into the PEG-rich phase was confirmed with 97.5% of the PEGylated fusion protein being detected in the PEG phase of a PEG 600–DEX 40 ATPS. This represents a 1322-fold increase in the protein partition coefficient in comparison to the non-PEGylated protein (Kc = 0.013). In the presence of pDNA containing a specific oligonucleotide recognition sequence, the zinc finger moiety of the PEGylated fusion protein bound to the plasmid and steered the complex to the PEG-rich phase. An increase in the proportion of pDNA that partitioned to the PEG-rich phase was observed as the concentration of PEGylated fusion protein was increased. Partitioning of the bound complex occurred to such an extent that no DNA was detected by the picogreen assay in the dextran phase. It was also possible to partition pDNA using a non-PEGylated (native) zinc finger–GST fusion protein in a PEG 1000–DEX 500 ATPS. In this case the native ligand accumulated mainly in the PEG phase. These results indicate good prospects for the design of new plasmid DNA purification methods using fusion proteins as affinity ligands.

Waveform type evaluation in congenital nystagmus

Congenital nystagmus is an ocular-motor disorder characterised by involuntary, conjugated and bilateral to and fro ocular oscillations. In this study a method to recognise automatically jerk waveform inside a congenital nystagmus recording and to compute foveation time and foveation position variability is presented. The recordings were performed with subjects looking at visual targets, presented in nine eye gaze positions; data were segmented into blocks corresponding to each gaze position. The nystagmus cycles were identified searching for local minima and maxima (SpEp sequence) in intervals centred on each slope change of the eye position signal (position criterion). The SpEp sequence was then refined using an adaptive threshold applied to the eye velocity signal; the outcome is a robust detection of each slow phase start point, fundamental to accurately compute some nystagmus parameters. A total of 1206 slow phases was used to compute the specificity in waveform recognition applying only the position criterion or adding the adaptive threshold; results showed an increase in negative predictive value of 25.1% using both features. The duration of each foveation window was measured on raw data or using an interpolating function of the congenital nystagmus slow phases; foveation time estimation less sensitive to noise was obtained in the second case. © 2010.

Waveguide fabrication in lithium-niobo-phosphate glasses by high repetition rate femtosecond laser:route to non-equilibrium material’s states

We study waveguide fabrication in lithium-niobo-phosphate glass, aiming at a practical method of single-stage fabrication of nonlinear integrated-optics devices. We observed chemical transformations or material redistribution during the course of high repetition rate femtosecond laser inscription. We believe that the laser-induced ultrafast heating and cooling followed by elements diffusion on a microscopic scale opens the way toward the engineering non-equilibrium sates of matter and thus can further enhance Refractive Index (RI) contrasts by virtue of changing glass composition in and around the fs tracks. © 2014 Optical Society of America.

LDL-Lipids from patients with hypercholesterolaemia and Alzheimer's disease are inflammatory to microvascular endothelial cells:mitigation by statin intervention

Elevated LDL concentration in mid-life increases the risk of developing Alzheimer's disease (AD) in later life. Increased oxidative modification (oxLDL) and nitration is observed during dementia and hypercholesterolemia. We investigated the hypothesis that statin intervention in mid-life mitigates the inflammatory effects of oxLDL on the microvasculature. Human microvascular endothelial cells (HMVEC) were maintained on transwells to mimic the microvasculature and exposed to patient and control LDL. Blood was obtained from statin-naïve, normo- and hyperlipidaemic subjects, AD with vascular dementia (AD-plus) and AD subjects (n=10/group) at baseline. Only hyperlipidaemic subjects with normal cognitive function received 40mg simvastatin intervention/day for three months. Blood was re-analysed from normo- and hyper-lipidaemic subjects after three months. LDL isolated from statin-naïve hyperlipidaemic, AD and AD-plus subjects was more oxidised (agarose gel electrophoretic mobility, protein carbonyl content and 8-isoprostane F2α) compared to control subjects. Statin intervention decreased protein carbonyls (2.5±0.4 Vs 3.95±0.2nmol/mg; P<0.001) and 8-isoprostane F2α (30.4±4.0 pg/ml Vs 43.5±8.42 pg/ml; P<0.05). HMVEC treatment with LDL-lipids from hyperlipidaemic, AD and AD-plus subjects impaired endothelial tight junction expression and decreased total glutathione levels (AD; 18.61±1.3, AD-plus; 16.5±0.7nmol/mg protein) compared to untreated cells (23.8±1.2 vs nmol/mg protein). Basolateral IL-6 secretion was increased by LDL-lipids from hyperlipidaemic (78.4±1.9 pg/ml), AD (63.2±5.9 pg/ml) and AD-plus (80.8±0.9 pg/ml) groups compared to healthy subject lipids (18.6±3.6 pg/ml). LDL-Lipids isolated after statin intervention did not affect endothelial function. In summary, LDL-lipids from hypercholesterolaemic, AD and AD-plus patients are inflammatory to HMVEC. In vivo intervention with statins reduces the damaging effects of LDL-lipids on HMVEC.

Theoretical perspectives in operations management:an analysis of the literature

Purpose - It is important to advance operations management (OM) knowledge while being mindful of the theoretical developments of the discipline. The purpose of this paper is to explore which theoretical perspectives have dominated the OM field. This analysis allows the authors to identify theory trends and gaps in the literature and to identify fruitful areas for future research. A reflection on theory is also practical, given that it guides research toward important questions and enlightens OM practitioners. Design/methodology/approach - The authors provide an analysis of OM theory developments in the last 30 years. The study encompasses three decades of OM publications across three OM journals and contains an analysis of over 3,000 articles so as to identify which theories, over time, have been adopted by authors in order to understand OM topics. Findings - The authors find that the majority of studies are atheoretical, empirical, and focussed upon theory testing rather than on theory development. Some theories, such as the resource-based view and contingency theory, have an enduring relevance within OM. The authors also identify theories from psychology, economics, sociology, and organizational behavior that may, in the future, have salience to explain burgeoning OM research areas such as servitization and sustainability. Research limitations/implications - The study makes a novel contribution by exploring which main theories have been adopted or developed in OM, doing so by systematically analyzing articles from the three main journals in the field (the Journal of Operations Management, Production and Operations Management, and the International Journal of Operations and Production Management), which encompass three decades of OM publications. In order to focus the study, the authors may have missed important OM articles in other journals. Practical implications - A reflection on theories is important because theories inform how a researcher or practicing manager interprets and solves OM problems. This study allows the authors to reflect on the collective OM journey to date, to spot trends and gaps in the literature, and to identify fruitful areas for future research. Originality/value - As far as the authors are aware, there has not been an assessment of the main theoretical perspectives in OM. The research also identifies which topics are published in OM journals, and which theories are adopted to investigate them. The authors also reflect on whether the most cited papers and those winning best paper awards are theoretical. This gives the authors a richer understanding of the current state of OM research.