Quantitative matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analysis of synthetic polymers and peptides

Matrix-assisted laser desorption ionization (MALDI) is a very powerful and widely used mass spectrometric technique to ionize high molecular weight compounds. The most commonly used dried droplet (DD) technique can lead to a concentration distribution of the analyte on the target and is therefore often not suitable for reproducible analyses. We developed a new solvent-free deposition technique, called compressed sample (CS), to prevent the distribution of the analytes caused by the crystallization of the compounds. The CS technique presented in this work allows the quantitative analysis of synthetic polymers such as derivatized maltosides with correlation coefficients of 0.999 and peptides up to 3500 Da with correlation coefficients of at least 0.982 without the use of stable-isotope-labeled standards.     

Beidseitige Innen‐ und Außenbeschichtung von PET‐Getränkeflaschen

Double‐sided interior and exterior coating of PET beverage bottles Plasma‐enhanced methods for the interior coating of PET beverage bottles have already been put into practice in the industry. Thereby the achieved barrier properties are limited due to defects in the coating, which emerge during the layer growth and allow a higher permeability. One possible way to improve barrier properties is the double‐sided coating. The implementation of the concept in form of a demonstrator plant is presented. By means of optical emission spectroscopy (OES) as a very versatile and easy to use method for the surveillance of industrial plasma processes, the influence of the gas composition on the plasma homogeneity and barrier properties of the coating is demonstrated. Permeation measurements are carried out, showing the potential of the combined coating process for the deposition of effective coatings.     

Explicit and implicit learning of event sequences: Evidence from event-related brain potentials.

Event-related potentials (ERPs) were recorded during a serial reaction time (RT) task, where single deviant items seldom (Experiment 1) or frequently (Experiment 2) replaced 1 item of a repeatedly presented 10-item standard sequence. Acquisition of sequence knowledge was reflected in faster RTs for standard as compared with deviant items and in an enhanced negativity (N2 component) of the ERP for deviant items. Effects were larger for participants showing explicit knowledge in their verbal reports and in a recognition test. The lateralized readiness potential indicated that correct responses were activated with shorter latencies after training. For deviant items, participants with explicit knowledge showed an initial activation of the incorrect but expected response. These findings suggest that the acquisition of explicit and implicit knowledge is reflected in different electrophysiological correlates and that sequence learning may involve the anticipatory preparation of responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Yeast Homologous Recombination Cloning Leading to the Novel Peptides Ambactin and Xenolindicin

Heterologous production of GameXPeptide A ( 1 ), as well as of the novel peptide natural products ambactin ( 2 ) and xenolindicins A–C ( 3 a – c ), was achieved by using the “overlap extension PCR‐yeast homologous recombination” (ExRec) method. ExRec cloning is based on the ability of yeast to assemble overlapping DNA fragments into functional plasmids. Here we used this technique to clone a total of 15 biosynthesis gene clusters from Photorhabdus and Xenorhabdus with sizes of up to 45 kb. The structures of the novel compounds 2 and 3 a , which were produced in Escherichia coli, were elucidated by detailed MS and bioinformatics analysis, and additionally confirmed by their chemical synthesis.     

Demographic/socio-economic factors and dietary habits determining consumer exposure to foodborne bacterial hazards in Turkey through the consumption of meat

Meat is considered a major source of foodborne bacterial pathogens. Assessing the risks for public health of meat consumption is achieved by “Risk Analysis”- a concept firmly established on a global level - so as to ensure the level of consumer protection as stipulated by international trade agreements. Risk analysis identifies and characterizes potential hazards, which allows estimating the associated risks, provided reliable data on consumer exposure are available. The latter varies by geographical region and associated differences in culture and socio-economic position of the consumer. This paper is dedicated to assessing the exposure of the Turkish population to bacterial hazards resulting from consumption of typical traditional meat dishes. It reviews current data on meat consumption in different regions of Turkey, on the basis of which seven typical preparations and consumption scenarios are identified. Major demographic and socio-economic differences along Turkey`s east–west axis were identified, such as the degree of urbanization, consumers’ age, household size, preferred meat animal species, frequency and volumes of meat consumption, and preparation techniques. Considering all these variables allowed a differentiated and reliable assessment of consumers’ exposure to biological hazards. This information is essential for greater accuracy in estimating the public health risks associated with various meat-borne hazards in this country.     

On-line signature verification

We describe a method for on-line handwritten signature verification. The signatures are acquired using a digitizing tablet which captures both dynamic and spatial information of the writing. After preprocessing the signature, several features are extracted. The authenticity of a writer is determined by comparing an input signature to a stored reference set (template) consisting of three signatures. The similarity between an input signature and the reference set is computed using string matching and the similarity value is compared to a threshold. Several approaches for obtaining the optimal threshold value from the reference set are investigated. The best result yields a false reject rate of 2.8% and a false accept rate of 1.6%. Experiments on a database containing a total of 1232 signatures of 102 individuals show that writer-dependent thresholds yield better results than using a common threshold.     

Rapid urease screening of Yersinia on CIN agar plates

Yersinia enterocolitica is an important foodborne pathogen, but isolation of virulent Yersinia from food sources is still time consuming and requires skills. In this article, we describe a rapid urease screening on cefsulodin-irgasan-novobiocin (CIN) agar plates with an agar overlay assay. This test is simple to perform, all colonies on a plate can be checked simultaneously, it only takes minutes for detection of urease-positive colonies and the colonies survive for transfer, further characterisation, and storage. Additionally, this method is useful to isolate virulent (urease-positive and pYV harbouring) Y. enterocolitica from foodstuffs.