Neuromodulation mit der Penta TM-Elektrode: neuroanatomisches Mapping - klinische Ergebnisse

Bei neuropathischen Schmerzen, die konservativ nicht ausreichend behandelt werden können, besteht die Therapiemöglichkeit mittels epiduraler Rückenmarkstimulation mit der PentaTM-Elektrode. Damit eine Schmerzreduktion erzielt werden kann, muss das zu therapierende Areal durch Parästhesien maskiert sein. Standardisiert findet die Elektrodenimplantation in Vollnarkose statt, sodass erst postoperativ die richtige Elektrodenposition feststellbar ist. Ziel der durchgeführten Studie war es zu analysieren, welche Körperregionen je nach Elektrodenlokalisation therapiert werden können und ob bei verschiedenen Patienten mit gleicher Elektrodenlokalisation dieselben Körperareale stimuliert werden. Hierfür wurde bei sechs Patienten untersucht, welche Körperareale je nach Kathodenlokalisation stimuliert wurden. Die Parästhesieausbreitung wurde bei 20 bipolaren Kontaktkonfigurationen bei einer Frequenz von 60 Hz und zwei Pulsweiten (100µs/400µs) ermittelt und mit der Lage der Kathode korreliert. Die Kathodenposition wurde mit einem Rückenmarkraster mit Hilfe von Röntgen/CT-Bildern bestimmt. Bei vier Patienten lag die Elektrode auf Wirbelkörperhöhe Th8. Es gab kein Körperareal, welches sich durch Kathoden in diesem Bereich bei allen Patienten zuverlässig stimulieren ließ. Eine identische Kathodenposition lag bei maximal drei Patienten vor. Weniger als 10% der insgesamt stimulierten Körperareale ließen sich bei den verschiedenen Patienten gleich stimulieren. Weitere Ergebnisse zeigten, dass die intraindividuelle Reproduzierbarkeit der stimulierten Areale bei lediglich 22,6-59,7% lag. Bei höherer Pulsweite (400µs) wurden signifikant mehr Körperareale stimuliert. Bei vertikaler Stimulationsrichtung wurden hingegen signifikant weniger Areale als bei diagonaler sowie vertikaler Richtung stimuliert. Zusammenfassend lassen die Daten keine zuverlässige Vorhersage auf die therapierbaren Körperareale in Abhängigkeit der Elektrodenposition zu, wobei dies postoperativ durch Stimulationsparameter moduliert werden kann

Unterstützung des Change Managements in Hochschulen durch qualitative Evaluation seitens der Studierenden

Der systematische Einsatz qualitativer Verfahren als Ergänzung zur dominierenden Praxis quantitativer Veranstaltungsevaluationen hat ein großes Potential insbeson­dere auch zur Begleitung eines universitären Change Management Prozesses. Der vorliegende Beitrag erörtert die aktuelle quantitative Evaluationspraxis und zeigt das Potential und die Eigenschaften der qualitativen Forschung (Offenheit, kommunikativer Charakter, Prozesscharakter, Explikation, Flexibilität) für Evalu­ationszwecke auf. Wie am Beispiel eines qualitativen Evaluationsprojektes an der Universität St. Gallen dargestellt wird, führt die ergänzende Anwendung qualitativer Verfahren zu einem konstruktiven Verständnis von Lehr- und Lehrunterrichts­evaluation, das der Überbrückung der Kluft zwischen der Messung und dem Ergreifen von Maß­nahmen zuträglich ist. 25.02.2007 | Karl WILBERS & Franziska ZELLWEGER (St. Gallen

A new simplified clarification approach for lentiviral vectors using diatomaceous earth improves throughput and safe handling

Lentiviral vectors have proven their great potential to serve as a DNA delivery tool for gene modified cell therapy and gene therapy applications. The downstream processing of these vectors is however still a great challenge, particularly because of the low stability of the virus. Harvesting and clarification are critical and until now insufficiently characterized steps for lentivirus processing. To address this bottleneck, we analyzed whether lentiviral vectors produced by transient transfection of HEK293 T/17 SF suspension cells can be efficiently clarified with a lab-scale method with the filter aid diatomaceous earth (DE) and bioburden reducing membrane filters achieving high lentivirus recoveries. Using a design of experiment approach we found that higher DE concentrations are advantageous for a higher turbidity reduction and shorter filtration times, but at the same time LV titer decreases with increasing DE concentration. A DE concentration of 9 g/L was identified with a DoE as a robust set-point. Clarification with DE was compared with for lab-scale traditionally employed centrifugation and subsequent bioburden reduction filtration of viral vectors. The use of DE allows to perform a harvest and clarification process, which does not only facilitate faster and safer virus handling, but enables a lower material consumption due to the extremely increased filter capacity, thus representing an efficient and robust lab-scale clarification process

Infectious titer determination of lentiviral vectors using a temporal immunological real-time imaging approach

The analysis of the infectious titer of the lentiviral vector samples obtained during upstream and downstream processing is of major importance, however, also the most challenging method to be performed. Currently established methods like flow cytometry or qPCR lack the capability of enabling high throughput sample processing while they require a lot of manual handling. To address this limitation, we developed an immunological real-time imaging method to quantify the infectious titer of anti-CD19 CAR lentiviral vectors with a temporal readout using the Incucyte® S3 live-cell analysis system. The infective titers determined with the Incucyte® approach when compared with the flow cytometry-based assay had a lower standard deviation between replicates and a broader linear range. A major advantage of the method is the ability to obtain titer results in real-time, enabling an optimal readout time. The presented protocol significantly decreased labor and increased throughput. The ability of the assay to process high numbers of lentiviral samples in a high throughput manner was proven by performing a virus stability study, demonstrating the effects of temperature, salt, and shear stress on LV infectivity

Steric exclusion chromatography of lentiviral vectors using hydrophilic cellulose membranes

Enveloped viral vectors like lentiviral vectors pose purification challenges due to their low stability. A gentle purification method is considered one of the major bottlenecks for lentiviral vector bioprocessing. To overcome these challenges, a promising method is steric exclusion chromatography which has been used to purify a variety of target molecules. In this study, we successfully identified optimal process parameters for steric exclusion chromatography to purify lentiviral vectors. Lentiviral vector particle recoveries and infectious recoveries of 86% and 88%, respectively, were achieved. The process parameters optimal for steric exclusion chromatography were determined as follows: polyethylene glycol with a molecular weight of 4000 Da, a polyethylene glycol concentration of 12.5%, and a flow rate of 7 mL⋅min$^{−1}$ using 5 layers of stabilized cellulose membranes as a stationary phase. High protein and dsDNA removal of approximately 80% were obtained. The remaining polyethylene glycol concentration in the eluate was determined. We defined the maximum loading capacity as 7.5 × 10$^{12}$ lentiviral particles for the lab device used and provide deeper insights into loading strategies. Furthermore, we determined critical process parameters like pressure. We demonstrated in our experiments that steric exclusion chromatography is a gentle purification method with high potential for fragile enveloped viral vectors as it yields high recoveries while efficiently removing impurities

Pre- and postoperative headache in patients with meningioma

Background Meningiomas are generally slowly growing intracranial tumors. They are often incidentally diagnosed, given that symptoms may be absent even in cases of an enormous tumor size. Headache is a frequent but not consistent symptom. Therefore, we examined the association between structural, biochemical and histochemical tumor parameters with preoperative as well as postoperative occurrence of headache. Methods In our study, we prospectively investigated 69 consecutive patients enrolled for meningioma neurosurgery. Anatomical, histological and biochemical parameters were acquired, and headache parameters were registered from the clinical report and from a questionnaire filled by the patients before neurosurgery. The headache was re-evaluated one year after neurosurgery. The study was designed to exploratively investigate whether there is an association of acquired clinical and biological parameters with the occurrence of preoperative and postoperative headache. Results Edema diameter and the proliferation marker MIB-1 were negatively associated with the incidence and intensity of preoperative headache, while the content of prostaglandin E2 in the tumor tissue was positively associated with preoperative headache intensity. Headache was more prevalent when the meningioma was located in the area supplied by the ophthalmic trigeminal branch. Compared to preoperative headache levels, an overall reduction was observed one year postoperative, and patients with a larger tumor had a higher headache remission. In parietal and occipital meningiomas and in those with a larger edema, the percentage of the headache remission rate was higher compared to other locations or smaller edema. Multivariable analyses showed an involvement of substance P and prostaglandin E2 in preoperative headache. Conclusions The study demonstrates new associations between meningiomas and headache. The postoperative headache outcome in the presented patient sample is encouraging for the performed neurosurgical intervention. These results should be tested in a prospective study that incorporates all patients with meningiomas

Monitoring Agronomic Parameters of Winter Wheat Crops with Low-Cost UAV Imagery

Monitoring the dynamics in wheat crops requires near-term observations with high spatial resolution due to the complex factors influencing wheat growth variability. We studied the prospects for monitoring the biophysical parameters and nitrogen status in wheat crops with low-cost imagery acquired from unmanned aerial vehicles (UAV) over an 11 ha field. Flight missions were conducted at approximately 50 m in altitude with a commercial copter and camera system—three missions were performed between booting and maturing of the wheat plants and one mission after tillage. Ultra-high resolution orthoimages of 1.2 cm·px−1 and surface models were generated for each mission from the standard red, green and blue (RGB) aerial images. The image variables were extracted from image tone and surface models, e.g., RGB ratios, crop coverage and plant height. During each mission, 20 plots within the wheat canopy with 1 × 1 m2 sample support were selected in the field, and the leaf area index, plant height, fresh and dry biomass and nitrogen concentrations were measured. From the generated UAV imagery, we were able to follow the changes in early senescence at the individual plant level in the wheat crops. Changes in the pattern of the wheat canopy varied drastically from one mission to the next, which supported the need for instantaneous observations, as delivered by UAV imagery. The correlations between the biophysical parameters and image variables were highly significant during each mission, and the regression models calculated with the principal components of the image variables yielded R2 values between 0.70 and 0.97. In contrast, the models of the nitrogen concentrations yielded low R2 values with the best model obtained at flowering (R2 = 0.65). The nitrogen nutrition index was calculated with an accuracy of 0.10 to 0.11 NNI for each mission. For all models, information about the surface models and image tone was important. We conclude that low-cost RGB UAV imagery will strongly aid farmers in observing biophysical characteristics, but it is limited for observing the nitrogen status within wheat crops

Regression kriging for improving crop height models fusing ultra-sonic sensing with UAV imagery

A crop height model (CHM) can be an important element of the decision making process in agriculture, because it relates well with many agronomic parameters, e.g., crop height, plant biomass or crop yield. Today, CHMs can be inexpensively obtained from overlapping imagery captured from unmanned aerial vehicle (UAV) platforms or from proximal sensors attached to ground-based vehicles used for regular management. Both approaches have their limitations and combining them with a data fusion may overcome some of these limitations. Therefore, the objective of this study was to investigate if regression kriging, as a geostatistical data fusion approach, can be used to improve the interpolation of ground-based ultrasonic measurements with UAV imagery as covariate. Regression kriging might be suitable because we have a sparse data set (ultrasound) and an exhaustive data set (UAV) and both data sets have favorable properties for geostatistical analysis. To confirm this, we conducted four missions in two different fields in total, where we collected UAV imagery and ultrasonic data alongside. From the overlapping UAV images, surface models and ortho-images were generated with photogrammetric processing. The maps generated by regression kriging were of much higher detail than the smooth maps generated by ordinary kriging, because regression kriging ensures that for each prediction point information from the UAV, imagery is given. The relationship with crop height, fresh biomass and, to a lesser extent, with crop yield, was stronger using CHMs generated by regression kriging than by ordinary kriging. The use of UAV data from the prior mission was also of benefit and could improve map accuracy and quality. Thus, regression kriging is a flexible approach for the integration of UAV imagery with ground-based sensor data, with benefits for precision agriculture-oriented farmers and agricultural service providers

Antibodies to the Junctional Adhesion Molecule Cause Disruption of Endothelial Cells and Do Not Prevent Leukocyte Influx into the Meninges after Viral or Bacterial Infection

A hallmark of infectious meningitis is the invasion of leukocytes into the subarachnoid space. In experimental meningitis triggered by tumor necrosis factor—α and interleukin-1β, the interaction of leukocytes with endothelial cells and the subsequent migration of the cells through the vessel wall can be inhibited by an antibody to the junctional adhesion molecule (JAM). In contrast to the cytokine-induced meningitis model, anti-JAM antibodies failed to prevent leukocyte influx into the central nervous system after infection of mice with Listeria monocytogenes or lymphocytic choriomeningitis virus. Furthermore, in bacterial meningitis, anti-JAM IgG antibodies, but not Fab fragments, caused disruption of the endothelium. Likewise complement-dependent antibody-mediated cytotoxicity was observed in cultured brain endothelial cells treated with anti-JAM IgG but not with its Fab fragmen

Body fat distribution and risk of incident ischemic stroke in men and women aged 50 to 74 years from the general population: the KORA Augsburg cohort study

It remains controversial whether measures of general or abdominal adiposity are better risk predictors for ischemic stroke. Furthermore, so far it is unclear whether body fat mass index (BFMI) and fat free mass index (FFMI) are risk predictors for ischemic stroke. This study examined the sex-specific relevance of body mass index (BMI), BROCA Index, waist circumference (WC), waist-height ratio (WHtR), BFMI and FFMI for the development of ischemic stroke in a Caucasian population.The prospective population-based cohort study was based on 1917 men and 1832 women (aged 50 to 74 years) who participated in the third (1994/95) or fourth (1999/2001) MONICA/KORA Augsburg survey. Subjects were free of stroke at baseline. Standardized anthropometric and bioelectric impedance measurements were obtained at baseline. Hazard ratios (HR) were estimated from Cox proportional hazard models.During a median follow-up of 9.3 years 128 ischemic strokes occurred in men and 81 in women, respectively. Coded as quartiles WC and WHtR were significantly associated with incident stroke in multivariable analyses in women (comparing the 4th vs. the bottom quartile), but none of the adiposity measures was significantly associated with incident stroke in multivariable adjusted analyses in men. When anthropometric measures were used as continuous variables, these findings were confirmed. After multivariable adjustment the associations between obesity measures and incident ischemic stroke were statistically significant only for WC (HR 1.39, 95%CI 1.12-1.72) and WHtR in women (HR 1.39, 95%CI 1.12-1.73) per increase of 1 standard deviation. In both sexes the measures BFMI and FFMI were no independent predictors for incident ischemic stroke.Abdominal obesity measures are independent predictors of incident ischemic stroke in women but not in men from the general adult population. Thus, it may be of particular importance for women to prevent central obesity in order to reduce their risk of ischemic stroke