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Search Results: 1 - 10 of 7458 matches for " Matthias Hartmann "
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Insights in 17β-HSD1 Enzyme Kinetics and Ligand Binding by Dynamic Motion Investigation
Matthias Negri,Maurizio Recanatini,Rolf W. Hartmann
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012026
Abstract: Bisubstrate enzymes, such as 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1), exist in solution as an ensemble of conformations. 17β-HSD1 catalyzes the last step of the biosynthesis of estradiol and, thus, it is a potentially attractive target for breast cancer treatment.
Global Locator, Local Locator, and Identifier Split (GLI-Split)
Michael Menth,Matthias Hartmann,Dominik Klein
Future Internet , 2013, DOI: 10.3390/fi5010067
Abstract: The locator/identifier split is an approach for a new addressing and routing architecture to make routing in the core of the Internet more scalable. Based on this principle, we developed the GLI-Split framework, which separates the functionality of current IP addresses into a stable identifier and two independent locators, one for routing in the Internet core and one for edge networks. This makes routing in the Internet more stable and provides more flexibility for edge networks. GLI-Split can be incrementally deployed and it is backward-compatible with the IPv6 Internet. We describe its architecture, compare it to other approaches, present its benefits, and finally present a proof-of-concept implementation of GLI-Split.
Heat shock inhibits lipopolysaccharide-induced tissue factor activity in human whole blood
Christoph Sucker, Kai Zacharowski, Matthias Thielmann, Matthias Hartmann
Thrombosis Journal , 2007, DOI: 10.1186/1477-9560-5-13
Abstract: Whole blood samples and leukocyte suspensions, respectively, from healthy probands (n = 12) were incubated with LPS for 2 hours under heat shock conditions (43°C) or control conditions (37°C), respectively. Subsequent to further 3 hours of incubation at 37°C the clotting time, a measure of tissue factor expression, was determined. Cell integrity was verified by trypan blue exclusion test and FACS analysis.Incubation of whole blood samples with LPS for 5 hours at normothermia resulted in a significant shortening of clotting time from 357 ± 108 sec to 82 ± 8 sec compared to samples incubated without LPS (n = 12; p < 0.05). This LPS effect was mediated by tissue factor, as inhibition with active site-inhibited factor VIIa (ASIS) abolished the effect of LPS on clotting time. Blockade of protein synthesis using cycloheximide demonstrated that LPS exerted its procoagulatory effect via an induction of tissue factor expression. Upon heat shock treatment, the LPS effect was blunted: clotting times were 312 ± 66 s in absence of LPS and 277 ± 65 s in presence of LPS (n = 8; p > 0.05). Similarly, heat shock treatment of leukocyte suspensions abolished the LPS-induced tissue factor activity. Clotting time was 73 ± 31 s, when cells were treated with LPS (100 ng/mL) under normothermic conditions, and 301 ± 118 s, when treated with LPS (100 ng/mL) and heat shock (n = 8, p < 0.05). Control experiments excluded cell damage as a potential cause of the observed heat shock effect.Heat shock treatment inhibits LPS-induced tissue factor activity in human whole blood samples and isolated leukocytes.Gram-negative sepsis is mediated by lipopolysaccharide (LPS), a bacterial membrane constituent, which activates toll like receptor 4 (TLR-4). The resulting complex biological responses include an activation of the immune, inflammatory and coagulation systems [1-4]. While active tissue factor is absent in the peripheral blood under physiological conditions, the activation of hemostasis during sep
Phantom of Human Adipose Tissue and Studies of Light Propagation and Light Absorption for Parameterization and Evaluation of Noninvasive Optical Fat Measuring Devices  [PDF]
Stefan Hartmann, Matthias Moschall, Oliver Sch?fer, Frank Stüpmann, Ulrich Timm, David Klinger, Jens Kraitl, Hartmut Ewald
Optics and Photonics Journal (OPJ) , 2015, DOI: 10.4236/opj.2015.52005
Abstract: A method for noninvasive determination of fat and water content in the human body is examined. A spatially resolved spectroscopy method is used which can record low intensity near infrared spectra. This novel approach is compared to other methods for the determination of fat and water content. Monte Carlo simulations of light propagation in tissue are shown and the production and characterization of optical phantoms of adipose tissue are investigated.
Whole blood impedance aggregometry as a biomarker for the diagnosis and prognosis of severe sepsis
Michael Adamzik, Klaus G?rlinger, Jürgen Peters, Matthias Hartmann
Critical Care , 2012, DOI: 10.1186/cc11816
Abstract: Eighty patients with severe sepsis and 50 postoperative patients were included in the prospective observational study. Platelet function was determined at the first day of severe sepsis and surgery, respectively, using impedance aggregometry (Multiplate?). Moreover, platelet count, procalcitonin, interleukin 6, C-reactive protein and 30-day mortality were determined.Compared to postoperative patients, platelet aggregation was significantly reduced in patients with severe sepsis (collagen-test: 70.8 (44.4, 83.2) arbitrary units (A.U.) vs. 26.8 (12.7, 45.8) A.U.; P <0.001; median and quartiles). Furthermore, marked differences in platelet function were observed in survivors and non-survivors of severe sepsis (collagen-test: 33.4 (10.9, 48.8) A.U. vs. 12.4 (6.5, 25.0) A.U.; P = 0.001). Kaplan-Meier analysis demonstrated that higher platelet function was associated with a mortality of 10%, while mortality was 40% when platelet function was low (collagen-test; P = 0.002). The odds ratio was 6.0. In both univariate and multivariate analyses (including procalcitonin, IL6, C-reactive protein and platelet count) impedance aggregometry using collagen as the activator proved to be the best and an independent predictor for the diagnosis and prognosis of severe sepsis in critical illness.In severe sepsis, impedance aggregometry allows better prediction of diagnosis and survival than conventional biomarkers and platelet count.Sepsis is the third most common cause of death in western countries. Despite the advances in intensive care medicine the prognosis of the disease has improved only gradually [1]. Concerning the pathophysiology, sepsis has been shown to be caused by a generalized and inappropriate activation of the immune system and hemostasis; both plasma components and platelets are affected by the disease [2].In recent years, evidence has accumulated that platelets and inflammation are tightly coupled. An active function of platelets in inflammation has recently been demon
The psychosocial evaluation of medically-ill inpatients: accordance between mental disorders and self-rated psychosocial distress
Fritzsche, Kurt,Burger, Thorsten,Hartmann, Armin,Nübling, Matthias
GMS Psycho-Social-Medicine , 2005,
Abstract: Background: Both psychometric questionnaires and structured psychodiagnostic interviews are used to identify medically-ill inpatients requiring psychotherapeutic treatment. The study examines the accordance between the diagnosis of a mental disorder (ICD-10) and self-rated psychosocial distress of unselected inpatients within the framework of a psychosomatic liaison service.Methods: Of n=532 consecutive patients hospitalized in five departments of the University Hospital Freiburg, n=357 patients underwent a structured psychodiagnostic interview (Mini-DIPS) to obtain diagnoses according to ICD-10 F. Psychosocial distress (HADS), somatoform symptoms (SOMS-2 J), quality of life (EDLQ) and coping strategies (FQCI) were evaluated by self-rating questionnaires.Results: A mental disorder requiring treatment was diagnosed in 44% of the patients. Predictors for the diagnosis of a mental disorder were the depression subscale of the HADS, the frequency of somatoform symptoms and depressive coping. The greatest accordance between mental disorders and screening instruments was found for the depression subscale of the HADS at a cut-off 8+. The area under the curve (AUC) was 0.75. With a specificity of 87% and a sensitivity of 53%, nearly half of all mental disorders requiring treatment were not identified by the HADS, especially in patients with neurotic, stress-related and somatoform disorders (F4), most of them cancer patients with adjustment disorders.Conclusions: Case selection by the HADS is successfull in disorders, where depressive symptoms are prevalent. For F4-diagnoses a lower cut-off of 6+ is recommended. The importance of a clinical interview is underlined. Other screening procedures, specific for the general hospital population, are discussed.
Spatial cognition, body representation and affective processes: the role of vestibular information beyond ocular reflexes and control of posture
Fred W. Mast,Nora Preuss,Matthias Hartmann,Luzia Grabherr
Frontiers in Integrative Neuroscience , 2014, DOI: 10.3389/fnint.2014.00044
Abstract: A growing number of studies in humans demonstrate the involvement of vestibular information in tasks that are seemingly remote from well-known functions such as space constancy or postural control. In this review article we point out three emerging streams of research highlighting the importance of vestibular input: (1) Spatial Cognition: Modulation of vestibular signals can induce specific changes in spatial cognitive tasks like mental imagery and the processing of numbers. This has been shown in studies manipulating body orientation (changing the input from the otoliths), body rotation (changing the input from the semicircular canals), in clinical findings with vestibular patients, and in studies carried out in microgravity. There is also an effect in the reverse direction; top-down processes can affect perception of vestibular stimuli. (2) Body Representation: Numerous studies demonstrate that vestibular stimulation changes the representation of body parts, and sensitivity to tactile input or pain. Thus, the vestibular system plays an integral role in multisensory coordination of body representation. (3) Affective Processes and Disorders: Studies in psychiatric patients and patients with a vestibular disorder report a high comorbidity of vestibular dysfunctions and psychiatric symptoms. Recent studies investigated the beneficial effect of vestibular stimulation on psychiatric disorders, and how vestibular input can change mood and affect. These three emerging streams of research in vestibular science are—at least in part—associated with different neuronal core mechanisms. Spatial transformations draw on parietal areas, body representation is associated with somatosensory areas, and affective processes involve insular and cingulate cortices, all of which receive vestibular input. Even though a wide range of different vestibular cortical projection areas has been ascertained, their functionality still is scarcely understood.
Long-Time Effects in a Simulation Model of Sputter Erosion
Alexander K. Hartmann,Reiner Kree,Ulrich Geyer,Matthias Koelbel
Physics , 2001, DOI: 10.1103/PhysRevB.65.193403
Abstract: A simple (2+1) dimensional discrete model is introduced to study the evolution of solid surface morphologies during ion-beam sputtering. The model is based on the same assumptions about the erosion process as the existing analytic theories. Due to its simple structure, simulations of the model can be performed on time scales, where effects beyond the linearized theory become important. Whereas for short times we observe the formation of ripple structures in accordance with the linearized theory, we find a rough surface with scaling properties for intermediate times. The long time behavior of the model strongly depends on the surface relaxation mechanism.
New Alzheimer Amyloid β Responsive Genes Identified in Human Neuroblastoma Cells by Hierarchical Clustering
Markus Uhrig, Carina Ittrich, Verena Wiedmann, Yuri Knyazev, Annette Weninger, Matthias Riemenschneider, Tobias Hartmann
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006779
Abstract: Alzheimer's disease (AD) is characterized by neuronal degeneration and cell loss. Aβ42, in contrast to Aβ40, is thought to be the pathogenic form triggering the pathological cascade in AD. In order to unravel overall gene regulation we monitored the transcriptomic responses to increased or decreased Aβ40 and Aβ42 levels, generated and derived from its precursor C99 (C-terminal fragment of APP comprising 99 amino acids) in human neuroblastoma cells. We identified fourteen differentially expressed transcripts by hierarchical clustering and discussed their involvement in AD. These fourteen transcripts were grouped into two main clusters each showing distinct differential expression patterns depending on Aβ40 and Aβ42 levels. Among these transcripts we discovered an unexpected inverse and strong differential expression of neurogenin 2 (NEUROG2) and KIAA0125 in all examined cell clones. C99-overexpression had a similar effect on NEUROG2 and KIAA0125 expression as a decreased Aβ42/Aβ40 ratio. Importantly however, an increased Aβ42/Aβ40 ratio, which is typical of AD, had an inverse expression pattern of NEUROG2 and KIAA0125: An increased Aβ42/Aβ40 ratio up-regulated NEUROG2, but down-regulated KIAA0125, whereas the opposite regulation pattern was observed for a decreased Aβ42/Aβ40 ratio. We discuss the possibilities that the so far uncharacterized KIAA0125 might be a counter player of NEUROG2 and that KIAA0125 could be involved in neurogenesis, due to the involvement of NEUROG2 in developmental neural processes.
Free hemoglobin concentration in severe sepsis: methods of measurement and prediction of outcome
Michael Adamzik, Tim Hamburger, Frank Petrat, Jürgen Peters, Herbert de Groot, Matthias Hartmann
Critical Care , 2012, DOI: 10.1186/cc11425
Abstract: Plasma concentration of free hemoglobin was determined in patients with severe sepsis (n = 161) and postoperative patients (n = 136) on day 1 of diagnosis and surgery. For the measurement of free hemoglobin, an enzyme linked immunosorbent assay and three spectrophotometric algorithms were used. Moreover, SAPS II- and SOFA scores as well as procalcitonin concentration and outcome were determined. Kaplan-Meier analysis was performed and odds ratios were determined after classification of free hemoglobin concentrations in a high and low concentration group according to the median. For statistical evaluation the Mann-Whitney test and logistic regression analysis were used.In non-survivors of severe sepsis, free hemoglobin concentration was twice the concentration compared to survivors. Thirty-day survival of patients, as evidenced by Kaplan-Meier analysis, was markedly lower in patients with high free hemoglobin concentration than in patients with low free hemoglobin concentration. Best discrimination of outcome was achieved with the spectrophotometric method of Harboe (51.3% vs. 86.4% survival, p < 0.001; odds ratio 6.1). Multivariate analysis including free hemoglobin, age, SAPS II- and SOFA-score and procalcitonin demonstrated that free hemoglobin, as determined by all 4 methods, was the best and an independent predictor for death in severe sepsis (p = 0.022 to p < 0.001). Free hemoglobin concentrations were not significantly different in postoperative and septic patients in three of four assays. Thus, free hemoglobin can not be used to diagnose severe sepsis in critical illness.Free hemoglobin is an important new predictor of survival in severe sepsis.Sepsis is the third common cause of death in western countries, but despite decades of research its prognosis has not improved markedly [1]. Concerning the pathophysiology leading to sepsis, a generalized inappropriate inflammation has been demonstrated [2]. While localized inflammation is an effective strategy to defe
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