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이종일,Adnan Ritzka,Thomas Scheper 한국생물공학회 2004 Biotechnology and Bioprocess Engineering Vol.9 No.3
Concentrations of substrates, glucose, and ammionia in biological processes have been on-line monitored by using glucose-flow injection (FIA) and ammonia-FIA systems. Based on the on-line monitored data the concentrations of substrates have been controlled by an on-off controller, a PID controller, and a neural network (NN) based controller. A simulation program has been developed to test the control quality of each controller and to estimate the control parameters. The on-off controller often produced high oscillations at the set point due to its low robustness. The control quality of a PID controller could have been improved by a high analysis frequency and by a short residence time of sample in a FIA system. A NN-based controller with 3 layers has been developed, and a 3(input)-2(hidden)-1(output) network structure has been found to be optimal for the NN-based controller. The performance of the three controllers has been tested in a simulated process as well as in a cultivation process of Saccharomyces cerevisiae, and the performance has also been compared to simulation results. The NN-based controller with the 3-2-1 network structure was robust and stable against some disturbances, such as a sudden injection of distilled water into a biological process.
Hyung Lim Elfrink,Wiep Scheper,Rob Zwart,Frank Baas 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.4
Disturbances in proteostasis are observed in many neurodegenerative diseases. This leads to activation of protein quality control to restore proteostasis, with a key role for the removal of aberrant proteins by proteolysis. The unfolded protein response (UPR) is a protein quality control mechanism of the endoplasmic reticulum (ER) that is activated in several neurodegenerative diseases. Recently we showed that the major proteolytic pathway during UPR activation is via the autophagy/lysosomal system. Here we investigate UPR induction if the other major proteolytic pathway of the ER -ER associated degradation (ERAD)- is inhibited. Surprisingly, impairment of ERAD results in decreased UPR activation and protects against ER stress toxicity. Autophagy induction is not affected under these conditions, however, a striking relocalization of the lyso-somes is observed. Our data suggest that a protective UPR-modulating mechanism is activated if ERAD is inhibited, which involves lysosomes. Our data provide insight in the cross-talk between proteolytic pathways involved in ER proteostasis. This has implications for neurodegenerative diseases like Alzheimer’s disease where disturbed ER proteostasis and proteolytic impairment are early phenomena in the pathology.
Chattopadhyay, Saurabh,Bisaria, V.S.,Scheper, T.,Srivastava, A.K. The Korean Society for Biotechnology and Bioengine 2002 Biotechnology and Bioprocess Engineering Vol.7 No.6
Culture conductivity and on-line NADH fluorescence were used to measure cellular growth in plant cell suspension cultures of Podophyllum hexandrum. An inverse correlation between dry cell weight and medium conductivity was observed during shake flask cultivation. A linear relationship between dry cell weight and culture NADH fluorescence was obtained during the exponential phase of batch cultivation In a bioreactor under the pH stat (pH 6) conditions. It was observed that conductivity measurement were suitable for biomass characterisation under highly dynamic uncontrolled shake flask cultivation conditions. However, if the acid/alkali feeding is done for pH control the conductivity measurement could not be applied. On the other hand the NADH fluorescence measurement allowed online-in situ biomass monitoring of rather heterogenous plant cell suspension cultures in bioreactor even under the most desirable pH stat conditions.
Aptamer-based Depletion of Small Molecular Contaminants: A Case Study Using Ochratoxin A
Emilia Schax,Maren Lönne,Thomas Scheper,Shimshon Belkin,Johanna-Gabriela Walter 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.6
Based on the increasing demand for detection and depletion of small molecules like mycotoxins or pesticides in food, water, or pharmaceuticals, aptamers are gaining more importance as sensitive, specific-depletion molecules. Here, we present an aptamer-based method for depletion of ochratoxin A (OTA) as a model system and show the advantages and the limitations of aptamers in the depletion of small molecular contaminants. OTA is a mycotoxin produced by various Penicillium and Aspergillus strains and is often found in grain and grain derivatives. We immobilized a well-described DNA aptamer against OTA on an agarose gel and used the column as a clean-up system. The aptamer shows a high specificity and sensitivity for OTA: Ochratoxin B, a molecule similar to OTA, was not bound by the aptamer; and a control oligonucleotide was not able to bind OTA. After optimizing the process for better economic feasibility, the column could be used for several times without loss of aptamer activity. We investigated the location of immobilized aptamer within the gel using fluorescent-labeled aptamers. Furthermore, beer samples spiked with OTA were used to investigate aptamer activity in complex samples. Using these complex samples we have observed a significant loss of aptamer activity. We have further investigated this limitation by performing microscale thermophoresis experiments to determine the KD values of the aptamer in different complex samples like beer, coffee, juice and wine. Our results indicate that the applicability of aptamers to real processes is currently restricted by the selection buffer used during its selection process (SELEX). We therefore suggest using conditions closer to those of the later application of the aptamer during future SELEX experiments.
Tomas Falk,Alexander J. Mrozek,Werner H. Kunz,Jeroen J.L. Schepers 글로벌지식마케팅경영학회 2014 Global Marketing Conference Vol.2014 No.7
Prior research has investigated the consumer effects of cash and card payments in service settings, but the growing trend of innovative payment with a mobile device hasn’t been considered in the literature so fare. This article represents one of the first studies that considers the adoption of mobile as a new payment method and investigate how the ‘checkout’ phase affect the shoppers’ overall price image of retail stores (OSPI). Results from our studies show that the ‘checkout’ phase is the ‘moment of truth’ for shoppers judging OSPI. We investigate the effects of cash, card, and mobile payments and show that the less transparent a payment method, the lower OSPI judgments of shoppers. In particular, favorable comparisons of basket prices to shoppers’ mental budgets trigger lower store price perceptions. Subsequently, these results have major implications for retailers aiming to lower their OSPI in customers’ minds.
Robin Eelsing,Ahmad Masih Ahmadi,Jens Anthony Halm,Tim Schepers 대한정형외과학회 2024 Clinics in Orthopedic Surgery Vol.16 No.1
Background: The sinus tarsi approach (STA) has gained popularity for the treatment of displaced intra-articular calcaneal fractures. No large studies comparing wound complications worldwide after STA surgery are available. The aim of this systematic review was to compare postoperative wound complication (POWC) and postoperative wound infection (POWI) rates following STA surgery between continents and countries and their differences in climate. Methods: A literature search was performed using the databases of PubMed, Embase, and the Cochrane Library. Studies published before January 1, 2000, including < 10 patients and written in a language other than English were excluded. Results: In total, 86 studies containing 4,392 surgeries via STA from 20 different countries were included. The mean POWC was 5.9% and the mean POWI was 4.4%. The highest median POWC rate was in North America (8.5%) and the lowest in South America (2.0%). No significant differences were found in the POWC and POWI rates between countries (p = 0.178 and p = 0.570, respectively), but significant differences were found between the POWC and POWI rates between continents (p = 0.011 and p = 0.036, respectively). The number of surgeries per year and climate differences, as represented by mean local temperature, were not correlated with both the POWC/POWI rates and functional outcome scores. Conclusions: Significant differences between the POWC and POWI rates were found between continents but not between individual countries. With a mean POWC of 5.9% and a mean POWI rate of 4.4%, STA has an intrinsic low risk for complications given the minimally invasive nature of the approach and is inevitably becoming the gold standard for calcaneal surgery.