Comparative study of non-invasive monitoring via infrared spectroscopy for mammalian cell cultivations.

Process analytical technology (PAT) is a guide to improve process development in biotech industry. Optical sensors such as near and mid infrared spectrometers fulfill an essential part for PAT. NIRS and MIRS were investigated as non-invasive on line monitoring tools for animal cell cultivations in order to predict critical process parameters, like cell parameters as well as substrate and metabolite concentrations. Eight cultivations were performed with frequent sampling. Variances between cultivations were induced by spiking experiments with intent to break correlations between analytes; to keep causality of the models; and to increase model robustness. Calibration models were built for each analyte using partial least-squares regression method. Cultivations chosen for validation were not part of the calibration set. Glucose concentration, cell density and viability were predicted by NIRS with a root mean square error of prediction (RMSEP) of 0.36 g/L, 3.9 10(6)cells/mL and 3.62% respectively. Based on MIR spectra glucose and lactate concentrations were predicted with a RMSEP of 0.16 and 0.14 g/L respectively. Results show that MIRS has higher accuracy regarding the prediction of single analytes. For prediction of a main course of a cultivation, NIRS is much better suited than MIRS.

[Card-based age control mechanisms at tobacco vending machines. Effect and consequences]. / Die kartenbasierte Alterskontrolle an Zigarettenautomaten. Wirkung und Folgen.

Until recently, 700,000 tobacco vending machines provided uncontrolled access to cigarettes for children and adolescents in Germany. On January 1, 2007, a card-based electronic locking device was attached to all tobacco vending machines to prevent the purchase of cigarettes by children and adolescents under 16. Starting in 2009, only persons older than 18 are able to buy cigarettes from tobacco vending machines. The aim of the present investigation (SToP Study: "Sources of Tobacco for Pupils" Study) was to assess changes in the number of tobacco vending machines after the introduction of these new technical devices (supplier's reaction). In addition, the ways smoking adolescents make purchases were assessed (consumer's reaction). We registered and mapped the total number of tobacco points of sale (tobacco POS) before and after the introduction of the card-based electronic locking device in two selected districts of the city of Cologne. Furthermore, pupils from local schools (response rate: 83%) were asked about their tobacco consumption and ways of purchase using a questionnaire. Results indicated that in the area investigated the total number of tobacco POSs decreased from 315 in 2005 to 277 in 2007. The rates of decrease were 48% for outdoor vending machines and 8% for indoor vending machines. Adolescents reported circumventing the card-based electronic locking devices (e.g., by using cards from older friends) and using other tobacco POSs (especially newspaper kiosks) or relying on their social network (mainly friends). The decreasing number of tobacco vending machines has not had a significant impact on cigarette acquisition by adolescent smokers as they tend to circumvent the newly introduced security measures.

["Why not?"--content analysis of answers from more than 700 pupils about their motives for not smoking]. / "Warum nicht?"-- Inhaltsanalyse der Motivangaben zum Rauchverzicht von über 700 Schülern.

BACKGROUND AND OBJECTIVE: In spite of declining smoking prevalence nothing is known about the motives of adolescents in Germany who abstain from smoking. If one knows what motives prevent youngsters from ever starting to smoke it would make it possible to adjust future preventive strategies that would reach the "hard core" of smoking adolescents. This study investigated the true motives of non-smokers and also focused on possible gender and social background as well as age differences in the structure of their motivation. METHOD: In the SToP-Study ("Sources of Tobacco for Pupils" Study 2008) 780 pupils, of whom 709 were non-smokers from 32 school classes, grades 7-9, were interviewed about their smoking experience. In anonymized answers to the questions pupils wrote down their motives for being non-smokers. A total of 1,329 free text statements, some of them very elaborate, were categorized and evaluated in a qualitative analysis. RESULTS: The most important and frequently mentioned motives for not smoking were health related (78,1%). But the most significant health risks of tobacco consumption (cardiac and cerebrovascular disease, chronic obstructive pulmonary disease), except cancer risk, were hardly appreciated. Other important reasons for not smoking were aesthetic aversion (38.6%), lacking perception of a benefit (25.1%) and economic motives (20.9%). It was especially female grammar school pupils who most frequently expressed health and aesthetic reasons (such as disgust, smell and taste aversion, dental and finger discolorations) as motives for not smoking. CONCLUSION: Extrinsic reasons (legal restrictions, smoking bans imposed by parents and schools, age limits etc.) are not important reasons to abstain for young non-smokers. Specifically, arguments about health, participation in sports and being in good physical condition should be central to any advice given to young smokers within the setting of general medical practice.

Implementation of electronic locking devices for adolescents at German tobacco vending machines: intended and unintended changes of supply and demand.

BACKGROUND: Starting from 1 January 2007, electronic locking devices based on proof-of-age (via electronic cash cards or a European driving licence) were installed in approximately 500,000 vending machines across Germany to restrict the purchase of cigarettes to those over the age of 16. OBJECTIVE: To examine changes in the number of tobacco vending machines before and after the introduction of these new measures. DESIGN: The total number of commercial tobacco sources in 2 selected districts (70,000 inhabitants) in Cologne were recorded and mapped. This major German city was the ideal setting for this study as investigators were able to use existing sociogeographical data from the area. A complete inventory was compiled in autumn 2005 and 2007. A total of 780 students aged 12 to 15 were also interviewed in the study areas. The main outcome measures were quantities and locations of commercial tobacco sources. RESULTS: Between 2005 and 2007 the total number of tobacco sources decreased from 315 to 277 within the study area. Although the most obvious reduction was detected in the number of outdoor vending machines (-48%), the number of indoor vending machines also decreased by 8%. Adolescents changed from vending machines to other sources for cigarettes, particularly kiosks or friends (+31% points usage rate, p<0.001; +35% points usage rate, p<0.001, respectively). CONCLUSIONS: Although the number of tobacco vending machines decreased, this has not had a significant impact on cigarette acquisition by underage smokers as they were able to circumvent this new security measure in several different ways.

Chemometric modelling based on 2D-fluorescence spectra without a calibration measurement.

MOTIVATION: 2D fluorescence spectra provide information from intracellular compounds. Fluorophores like trytophan, tyrosine and phenylalanin as well as NADH and flavins make the corresponding measurement systems very important for bioprocess supervision and control. The evaluation is usually based on chemometric modelling using for their calibration procedure off-line measurements of the desired process variables. Due to the data driven approach lots of off-line measurements are required. Here a methodology is presented, which enables to perform a calibration procedure of chemometric models without any further measurement. RESULTS: The necessary information for the calibration procedure is provided by means of the a priori knowledge about the process, i.e. a mathematical model, whose model parameters are estimated during the calibration procedure, as well as the fact that the substrate should be consumed at the end of the process run. The new methodology for chemometric calibration is applied for a batch cultivation of aerobically grown S. cerevisiae on the glucose Schatzmann medium. As will be presented the chemometric models, which are determined by this method, can be used for prediction during new process runs. AVAILABILITY: The MATHLAB routine is free available on request from the authors.