Showing papers by "Wolfgang Wagner published in 2001"

Stochastic Particle Approximations for Smoluchoski’s Coagualtion Equation

Abstract: This paper studies stochastic particle approximations for Smoluchowski’s coagulation equation. A new stochastic algorithm with reduced variance is proposed. Its convergence behavior is investigated, when the number of simulation particles tends to infinity. Under appropriate assumptions on the coagulation kernel, the limit is the unique solution of the coagulation equation. Then detailed numerical experiments are performed, testing the applicability and efficiency of the algorithm. In particular, the gelation phenomenon (loss of mass in the coagulation equation) is studied numerically for several kernels. A striking feature of the new algorithm is a better convergence after the gelation point, providing a tool for detecting the mass of the gel.

Frameless neuronavigation in intracranial endoscopic neurosurgery.

Abstract: Object. Frameless computerized neuronavigation has been increasingly used in intracranial endoscopic neurosurgery. However, clear indications for the application of neuronavigation in neuroendoscopy have not yet been defined. The purpose of this study was to determine in which intracranial neuroendoscopic procedures frameless neuronavigation is necessary and really beneficial compared with a free-hand endoscopic approach. Methods. A frameless infrared-based computerized neuronavigation system was used in 44 patients who underwent intracranial endoscopic procedures, including 13 third ventriculostomies, nine aqueductoplasties, eight intraventricular tumor biopsy procedures or resections, six cystocisternostomies in arachnoid cysts, five colloid cyst removals, four septostomies in multiloculated hydrocephalus, four cystoventriculostomies in intraparenchymal cysts, two aqueductal stent placements, and fenestration of one pineal cyst and one cavum veli interpositi. All interventions were successfully accomplished. In all procedures, the navigational system guided the surgeons precisely to the target. Navigational tracking was helpful in entering small ventricles, in approaching the posterior third ventricle when the foramen of Monro was narrow, and in selecting the best approach to colloid cysts. Neuronavigation was essential in some cystic lesions lacking clear landmarks, such as intraparenchymal cysts or multiloculated hydrocephalus. Neuronavigation was not necessary in standard third ventriculostomies, tumor biopsy procedures, and large sylvian arachnoid cysts, or for approaching the posterior third ventricle when the foramen of Monro was enlarged. Conclusions. Frameless neuronavigation has proven to be accurate, reliable, and extremely useful in selected intracranial neuroendoscopic procedures. Image-guided neuroendoscopy improved the accuracy of the endoscopic approach and minimized brain trauma.

Wertigkeit eines qualitativen Regressionsgradings als prognostischer Faktor für das Überleben bei präoperativ radiochemotherapierten Patienten mit fortgeschrittenen Kopf-Hals-Karzinomen

Abstract: Multimodale Behandlungskonzepte gewinnen zunehmend an Bedeutung bei lokal fortgeschrittenen Kopf-Hals-Karzinomen. Die quantitative Aufarbeitung der histologischen Operationspraparate bezuglich der Tumorregression ist nachweisbar fur viele Tumorentitaten ein unabhangiger prognostischer Parameter. In der Literatur werden unterschiedliche Tumorregressionssysteme verwandt. Wir stellen einen einfachen, kostengunstigen Score anhand praoperativ radiochemotherapeutisch behandelter Kopf-Hals-Tumor-Patienten vor. Patienten und Methode: 43 Patienten mit Kopf-Hals-Tumoren im Stadium IV (AJCC) wurden neoadjuvant sequentiell mit zwei Zyklen Chemotherapie (Ifosfamid 1,5g/m2 Tag 1–5 unter Mesna-Schutz [300 mg/m2], Cisplatin 60 mg/m2 Tag 5, Tag 22 zweiter Zyklus) und ab Tag 29 akzeleriert hyperfraktionierter Bestrahlung (30 Gy) behandelt. Nach der histologischen Aufarbeitung der Operationspraparate erfolgte eine Aufteilung in vier Gruppen: Regressionsgrad I – keine Karzinomreste; Grad II – Karzinomnekrose; Grad III – partiell geschadigtes Karzinom; Grad IV – vitales Karzinom. Ergebnisse: Die 1-Jahres-Uberlebensrate betrug 79%, die 2-Jahres-Uberlebensrate 56% fur das Gesamtklientel [Overall-Survival]. Es fand sich eine signifikante Korrelation zwischen der qualitativen Tumorregression und dem Uberleben. Die 1-Jahres-Uberlebensrate in Abhangigkeit zur Regression des Primarius betrug 94% (Grad I), 80% (Grad II), 60% (Grad III) und 56% (Grad IV), die 2-Jahres-Uberlebensrate 76%, 40%, 40% und 11% (p < 0,01). Ahnlich fielen die Ergebnisse fur die Lymphknotenregression aus. Schlussfolgerung: Die histologische Regression nach vorausgehender Radiochemotherapie ist ein signifikanter Prognosefaktor bezuglich des Uberlebens. Wir stellen ein einfaches System mit vier Subgruppen vor, welches einen prognostischen Wert zu haben scheint und ohne zusatzlichen Aufwand und Kosten anwendbar ist. Zur Diskussion steht eine Therapieeskalation bei Patienten, die auf die Induktionstherapie gut angesprochen haben, um fur diese Subklientel eine weitere Verbesserung der Prognose zu erzielen.

Neonatal rat cartilage has the capacity for tissue regeneration

Abstract: One of the most relevant issues in future medicine is tissue regeneration. Transplantation medicine alone cannot solve the problem of incurable conditions of vital organs. One approach to this might be the replication of the spontaneous regeneration that is found in embryonic/neonatal tissue. In this study, a tissue model for basic investigation of regeneration mechanisms in vivo was established. We demonstrated by histology and immunohistochemical staining for types I and II collagen that neonatal rat cartilage unlike adult cartilage has the capacity for rapid scarfree regeneration after full-thickness incision. The underlying mechanism was identified in the preserved proliferative capacity of neonatal chondrocytes. This in vivo model should prove useful in further studies of the role of cellular (e.g., GA cell cycle regulators) and extracellular (e.g., cytokines) factors in tissue regeneration and wound healing.

"The train departed without us" - Public perceptions of biotechnology in ten European countries *

Abstract: In recent years it has become clear that biotechnology cannot be commercialised without considering the concerns voiced by the public. While it certainly cannot be assumed that the public has clear and consistent attitudes about ideas they have not previously encountered, it probably is as misleading to assume that they are completely unprepared to evaluate the new achievements they are confronted with. This „empty vessels fallacy“ may lead to strong opposition when public sentiment and its major concerns are neglected. For the public,understanding the innovation means giving meaning to it on the basis of everyday experiences.This process of “symbolic coping” is a essentially collective enterprise of information-seeking and processing which cannot be assumed to rely exclusively on sources of scientific risk-assessment. Rather, for the public, it will be conclusive whether the innovation is compatible with their needs, values and experiences or not. In order to achieve a deeper understanding of such public concerns, we set out to run a number of focus groups with a minimum of four groups and 5-8 discussants per group in each of ten European countries (Austria, Denmark, Finland, France, Germany, the United Kingdom, Italy,Portugal, Sweden and Switzerland). The participants were not selected to be statistically representative but rather the aim was to choose people who were likely to articulate a wide range of concerns. In addition to age, gender and level of education, country-specific selection criteria were used. In order to attempt the ambitious task of drawing comparative conclusions across a number of European countries, key aspects of the research – for example, the content of the moderator’s topic guide, the analysis process and the final interpretation – were a collective enterprise involving researchers of the EUDEB/LSES project in a number of meetings and two workshops. It was surprising to see, when comparing the national data, that there were far more commonalities than differences among the ten countries. Although often illustrated in the context of national events, there are a number of widely shared concerns across the European publics.When focusing on these common themes in this paper, this necessarily must remain a fragmentary enterprise. We will begin with the general question on the nature of biotechnology and its object, living nature. Polarised views of nature lead to different evaluations on whether biotechnology should be seen as just one technology like many others or as something radically new and different. Equally, these models of nature relate to the degree to which future consequences of the technology are seen to be predictable. In the second part of the chapter we will deal with the groups’ considerations of biotechnology’s consequences, advantages and disadvantages for their everyday lives. We investigate this evaluative process in terms of compatibility with needs, values and past experiences. These aspects will help to understand why evaluations of specific applications of biotechnology differ so much. In the third part we address the public’s questions on “who is involved?”, “who are the addressees of risks and benefits?”,and “how are decisions made?”, thus tapping into the fields of trust and responsibility.

Ypt protein prenylation depends on the interplay among levels of Rab escort protein and geranylgeranyl diphosphate in yeast cells.

Abstract: Farnesyl diphosphate (FPP), an intermediate of the sterol biosynthetic pathway, is used by farnesyl transferase to farnesylate, among others, the Ras proteins, and by geranylgeranyl diphosphate synthase to produce geranylgeranyl diphosphate (GGPP). GGPP is then transferred by geranylgeranyl transferase II (GGTase II) to Rab/Ypt members of the Ras superfamily known to be required at all stages of vesicle transport in both mammals and yeast. Formation of a complex between a Rab/Ypt protein and an accessory protein named the Rab escort protein (REP) is a prerequisite for GGTase II substrate recognition. Little is known about the factors that regulate GGTase II activity in living cells but, based on available data, it seems possible that vesicle transport in higher eukaryotes is regulated by the levels of prenylated Rab/Ypt proteins in the cells. Here we show that the levels of REP play an important role in regulating GGTase II activity in yeast cells if sufficient substrates are present. Moreover, overexpression of REP causes, directly or indirectly, an increased level of Ypt substrates available for prenylation, which in turn leads to the depletion of the GGPP pool in the cell. Overall our data suggest that the levels of REP and the availability of GGPP play a role in regulating Ypt protein prenylation.

An analysis of complementary/alternative medicine (CAM) use by radiotherapy patients

Abstract: Background Complementary/ alternative medicine (CAM) is gaining ever more importance in the treatment of radiotherapy patients. The purpose of this analysis was the statistical description of the preparations and treatments used by the patients. Material and methods: From May to November 2000, the statements from 250 patients of the Paracelsusklinik were analyzed. Patients comprised 135 women and 115 men with a median age of 59 years. Results: 44% did not carry out any further supplementary treatment measures except standard care; 2% could not state whether they took any additional preparations; 54% admitted carrying out an additional treatment. Preparations were distributed as follows: vitamins were taken by 98 patients (39%), immunostimulants like mistle and thymus preparations by 54 patients (21%), minerals by 42 patients (17%) - 12 of these patients used selenium -, roborants by 32 patients (13%) and various other substances/therapies by 43 patients (17%). Conclusion: More than half of all tumor patients used CAM. Vitamins, mistle/ thymus preparations and minerals constitute the majority of these preparations. The radiation oncologist has to include these treatments into his considerations. The value of such preparations has yet to be tested in further studies.

Is HLA-DR4 or the HLA-DRB1*0402 allele associated with decreased risk for CML?

Abstract: Leukemia In our study we determined MRP activity with a flow cytometric assay6 in the context of MRP1 deletion in 11 inv(16) AML patients. A correlation was observed between MRP activity and the occurrence of MRP1 deletions (r = 0.91, P , 0.01), suggesting an important role for MRP1. However, we observed an up-regulation of the MRP1 homologues MRP2 and MRP6, especially in those patient samples with one MRP1 deletion. In addition we observed a high activity of P-gp in one of the AML patients with MRP1 deletion. No association was found between MRP1 deletion and clinical outcome in the AML patients. In conclusion, it seems likely that in the case of a deletion of a transporter gene, the function might be compensated for by other transporter proteins, which might also affect the clinical outcome in inv(16) AML patients.

Cluster shapes and cluster sizes in the HERA-B silicon vertex detector

Abstract: We report on investigations of shape and size of the clusters on the silicon detectors of the HERA-B vertex detector. The data taken during the commissioning run of 1999 are compared to predictions of model calculations.

Large scale soil moisture monitoring using C-band scatterometer data.

Abstract: A method for monitoring soil moisture patterns using C-band scatterometers is described. The aim of this paper is not to go into the technical details of the retrieval algorithm, but rather to put the technique into context with previous efforts in active microwave remote sensing research and to point out a number of applications.

Online monitoring in the CDF II experiment

Abstract: We describe the online monitoring system of the CDF II experiment designed to check the data quality of all subsystems in real-time. A subset of the events accepted by the highest trigger level is made available to 10 analysis programs which check the data quality on an event-by-event basis and produce diagnostic histograms. The monitoring results are distributed to the user via a client-server scheme. The display clients feature an intuitive GUI which allows to browse and request the available results. The monitoring package is coded in C++ and makes use of the ROOT analysis framework which offers histogramming methods, networking classes and graphics handling. We report about the design and the implementation of the monitoring system and discuss our experiences during the first months of operation. The Collider Detector at Fermilab (CDF) is a general purpose detector operating at the Tevatron pp collider located in Batavia, Illinois. During Run I, from 1992 to 1996, the Tevatron operated at √ s = 1.8 TeV and CDF collected data with an integrated luminosity of L = 110 pb−1. Numerous high quality physics results were obtained, among them the discovery of the top quark, the discovery of the Bc meson and first indications on CP violation in the system of neutral mesons. From 1996 to 2001 the Tevatron collider was upgraded to provide an instantaneous luminosity of about 2 · 1032 cm−2s−1, i.e. 20 times more than in Run I, at √s = 2.0 TeV. The larger data samples to be expected in Run II, lasting from 2001 to 2007, will allow to repeat measurements of Run I with higher precision and perform new ones which were out of reach before. In order to prepare for the improved conditions CDF was considerably upgraded in all subsystems. Among these upgrades are new monitoring programs to control the data quality which are described in this article. ∗Speaker. †wagner@ekp.physik.uni-karlsruhe.de h e p 2 0 0 1 EPS HEP 2001 Wolfgang Wagner 1. Goals and system requirements Our main goal is to monitor the data quality of all subsystems of CDF online, while the data are being taken. The monitoring is realized by consistency checks on an event-by-event basis, by filling diagnostic histograms or time-charts, which show the time development of certain quantities, and by performing periodic statistical tests of the bin contents of those histograms. Furthermore, we want to report discovered errors in an automatic way to run control and thereby allow to request an automatic action, e.g. to reset or reboot faulty front-end crates or even halt, recover and restart the run. At the end of each run each monitoring program should give a final assessment of run quality. The judgments should be stored in a data base to give an overview and allow access by higher level assessment programs. Additionally, we want to use the monitoring programs offline, for example to check reconstructed data, to analyze test beam data or for primary checks on Monte Carlo data sets. To accomplish the goals mentioned above our monitoring system needs to fulfill certain technical requirements: (1) avoid interference with the data acquisition; (2) select events according to the trigger types; (3) parallelize concurrent tasks, like monitoring different subdetectors or different quantities; (4) guarantee each monitoring process an adequate input rate of minimum 1 Hz; (5) minimize the interference between the monitoring process and the display process, which delivers and visualizes the monitoring results to the user; the communication with the user should not slow down the monitoring process considerably; (6) implement structures and interfaces which are common to all monitoring processes; we named this common basis for all monitoring programs, which are in CDF jargon called consumers, the Consumer Framework [2]; (7) offer access to the monitoring results from remote institutions; that is important since not all subsystem experts are permanently located at Fermilab. (8) an easy-to use and versatile graphical user interface (GUI); (9) stable operation for long time periods; (10) a large part of the Consumer Framework should be kept independent of the CDF framework; this allows us to develop a universal tool which can be ported easily to other applications. 2. Design of the Consumer Framework The highest trigger level (Level 3) of the CDF II experiment is a software trigger implemented on a large PC farm. The available bandwidth for data logging is 20 Mbyte/s, the approximate size of an event is 250 kByte. Therefore, the expected trigger output rate is typically 75 Hz. The data are transfered from Level 3 to a process called Consumer Server Logger (CSL) [3] which sends the data to the computer center where they are written to tape and forwards copies of a subset of these events to the online monitoring programs. The total bandwidth available to the consumers is limited to 10 MByte/s. The Consumer Framework is written in C++ and makes heavy use of the ROOT [4] package. Monitoring programs: The CSL serves in total 10 monitoring programs: YMon (occupancies), XMon (trigger rates), LumMon (luminosity), TrigMon (trigger bits, trigger decisions), Stage0 (drift chamber calibrations), BeamMon (beam position), ObjectMon

Empfehlungen des Arbeitskreises «Supportive Maßnahmen in der Onkologie» zur klinischen Anwendung von Zytoprotektiva

Abstract: Recommendations of the Working Group ‘Supportive Masnahmen in der Onkologie’ concerning the Clinical Use of Cytoprotectives Leider besteht fur diesen Artikel keine Zusammenfassung.

T cells play a role in hematological malignancies as well as solid tumors

Abstract: Tcells and MHC classI- andII-restricted antigens (Ags) from solidtumors, especially melanoma, wasfocused on because: (1) melanoma is thebest-studied human tumor model forimmunotherapy; and (2) the majority ofMHC classII-restricted tumor Agsidentified to date are melanoma Ags. Theavailability of such Ags has led to manyclinical trials as well as animal studies.These studies indicate a requirement forCD4