97 results on '"Niemann U"'
Search Results
52. Heterogeneous reactions and chemical transport of molybdenum with halogens and oxygen under steady state conditions of incandescent lamps
- Author
-
Dittmer, G., primary and Niemann, U., additional
- Published
- 1983
- Full Text
- View/download PDF
53. Inhibition of experimental urinary bladder carcinogenesis by partial cystectomy
- Author
-
Kunze, E., primary, Wöltjen, H.-H., additional, and Niemann, U., additional
- Published
- 1983
- Full Text
- View/download PDF
54. ChemInform Abstract: PREPARATION AND REACTIONS OF PERFLUOROHALOORGANOSULFENYL HALIDES
- Author
-
HAAS, A., primary and NIEMANN, U., additional
- Published
- 1976
- Full Text
- View/download PDF
55. Inhibition of Experimental Urinary Bladder Carcinogenesis by Partial Cystectomy. Letter to the Editor
- Author
-
Kunze, E., primary, Wöltjen, H.-H., additional, and Niemann, U., additional
- Published
- 1984
- Full Text
- View/download PDF
56. ChemInform Abstract: (PERHALOMETHYLTHIO)HETEROCYCLES. X. ACID‐CATALYZED SUBSTITUTIONS ON (PERCHLOROFLUOROMETHYLTHIO)PYRROLES AND THEIR AGROBIOLOGICAL ACTIVITIES
- Author
-
DORN, S., primary, EGGENBERG, P., additional, GERSTENBERGER, M. R. C., additional, HAAS, A., additional, NIEMANN, U., additional, and ZOBRIST, P., additional
- Published
- 1979
- Full Text
- View/download PDF
57. 29Si-Kernresonanzmessungen an Siliciumhalogeniden / 29Si NMR Studies on Silicon Halogenides
- Author
-
Niemann, U., primary and Marsmann, H. C., additional
- Published
- 1975
- Full Text
- View/download PDF
58. ChemInform Abstract: BIS(PENTAFLUOROPHENYL)AZIDOPHOSPHANE
- Author
-
HORN, H.‐G., primary, GERSEMANN, M., additional, and NIEMANN, U., additional
- Published
- 1976
- Full Text
- View/download PDF
59. ChemInform Abstract: Study of the Heterocomplexes in the Vapor of the Na-Sn-Br-I System and Their Relevance for Metal Halide Lamps.
- Author
-
MILLER, M., NIEMANN, U., and HILPERT, K.
- Published
- 1995
- Full Text
- View/download PDF
60. Zirconocene dipicolinate and related dicarboxylate complexes: coordination geometries and reactivities
- Author
-
Niemann, U., Diebold, J., Troll, C., and Rief, U.
- Published
- 1993
- Full Text
- View/download PDF
61. Study of the NaBr–DyBr3 phase diagram by differential thermal analysis
- Author
-
Kobertz, D., Miller, M., Niemann, U., Singheiser, L., and Hilpert, K.
- Subjects
- *
ANALYTICAL chemistry , *THERMAL analysis , *FLUIDS , *THERMOGRAVIMETRY - Abstract
Abstract: The phase diagram of the quasi binary NaBr–DyBr3 system was determined by differential thermal analysis (DTA) applied to 27 samples covering the complete composition range of the system. The 3NaBr*DyBr3(s) compound is present in the solid-phase in addition to the pure component halides NaBr(s) and DyBr3(s). The DyBr3(s) and 3NaBr*DyBr3(s) phases showed a polymorphic transition at 1112 and at 733K, respectively. The {DyBr3(s)+3NaBr*DyBr3(s)} eutectic mixture melts at 709K giving a liquid of the molar composition x(NaBr)=0.62. The 3NaBr*DyBr3(s) phase melts peritectically at 765K. The phase diagram obtained in the present study virtually agrees with the calculated one available in literature. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
62. Comprehensive chemical kinetic modeling of the oxidation of 2-methylalkanes from C7 to C20
- Author
-
Sarathy, S.M., Westbrook, C.K., Mehl, M., Pitz, W.J., Togbe, C., Dagaut, P., Wang, H., Oehlschlaeger, M.A., Niemann, U., Seshadri, K., Veloo, P.S., Ji, C., Egolfopoulos, F.N., and Lu, T.
- Subjects
- *
CHEMICAL kinetics , *OXIDATION , *ALKANES , *CARBON isotopes , *FLAME , *CHEMICAL reactors , *METHYLATION , *REACTION mechanisms (Chemistry) - Abstract
Abstract: Conventional petroleum jet and diesel fuels, as well as alternative Fischer–Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed and reduced chemical kinetic mechanism for singly methylated iso-alkanes (i.e., 2-methylalkanes) ranging from C7 to C20. The mechanism also includes an updated version of our previously published C8–C16 n-alkanes model. The complete detailed mechanism contains approximately 7200 species 31400 reactions. The proposed model is validated against new experimental data from a variety of fundamental combustion devices including premixed and non-premixed flames, perfectly stirred reactors and shock tubes. This new model is used to show how the presence of a methyl branch affects important combustion properties such as laminar flame propagation, ignition, and species formation. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
63. Editorial: Artificial intelligence and mental health care.
- Author
-
Simões JP, Ten Klooster P, Neff PK, Niemann U, and Kraiss J
- Subjects
- Humans, Mental Health, Artificial Intelligence, Mental Health Services
- Abstract
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.
- Published
- 2024
- Full Text
- View/download PDF
64. Heterogeneity in response to treatment across tinnitus phenotypes.
- Author
-
Niemann U, Boecking B, Brueggemann P, Spiliopoulou M, and Mazurek B
- Subjects
- Humans, Combined Modality Therapy, Precision Medicine, Phenotype, Quality of Life, Tinnitus therapy
- Abstract
The clinical heterogeneity of chronic tinnitus poses major challenges to patient management and prompts the identification of distinct patient subgroups (or phenotypes) that respond more predictable to a particular treatment. We model heterogeneity in treatment response among phenotypes of tinnitus patients concerning their change in self-reported health burden, psychological characteristics, and tinnitus characteristics. Before and after a 7-day multimodal treatment, 989 tinnitus patients completed 14 assessment questionnaires, from which 64 variables measured general tinnitus characteristics, quality of life, pain experiences, somatic expressions, affective symptoms, tinnitus-related distress, internal resources, and perceived stress. Our approach encompasses mechanisms for patient phenotyping, visualizations of the phenotypes and their change with treatment in a projected space, and the extraction of patient subgroups based on their change with treatment. On average, all four distinct phenotypes identified at the pre-intervention baseline showed improved values for nearly all the considered variables following the intervention. However, a considerable intra-phenotype heterogeneity was noted. Five clusters of change reflected variations in the observed improvements among individuals. These patterns of treatment effects were identified to be associated with baseline phenotypes. Our exploratory approach establishes a groundwork for future studies incorporating control groups to pinpoint patient subgroups that are more likely to benefit from specific treatments. This strategy not only has the potential to advance personalized medicine but can also be extended to a broader spectrum of patients with various chronic conditions., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
65. Prognostic role of radiomics-based body composition analysis for the 1-year survival for hepatocellular carcinoma patients.
- Author
-
Saalfeld S, Kreher R, Hille G, Niemann U, Hinnerichs M, Öcal O, Schütte K, Zech CJ, Loewe C, van Delden O, Vandecaveye V, Verslype C, Gebauer B, Sengel C, Bargellini I, Iezzi R, Berg T, Klümpen HJ, Benckert J, Gasbarrini A, Amthauer H, Sangro B, Malfertheiner P, Preim B, Ricke J, Seidensticker M, Pech M, and Surov A
- Abstract
Background: Parameters of body composition have prognostic potential in patients with oncologic diseases. The aim of the present study was to analyse the prognostic potential of radiomics-based parameters of the skeletal musculature and adipose tissues in patients with advanced hepatocellular carcinoma (HCC)., Methods: Radiomics features were extracted from a cohort of 297 HCC patients as post hoc sub-study of the SORAMIC randomized controlled trial. Patients were treated with selective internal radiation therapy (SIRT) in combination with sorafenib or with sorafenib alone yielding two groups: (1) sorafenib monotherapy (n = 147) and (2) sorafenib and SIRT (n = 150). The main outcome was 1-year survival. Segmentation of muscle tissue and adipose tissue was used to retrieve 881 features. Correlation analysis and feature cleansing yielded 292 features for each patient group and each tissue type. We combined 9 feature selection methods with 10 feature set compositions to build 90 feature sets. We used 11 classifiers to build 990 models. We subdivided the patient groups into a train and validation cohort and a test cohort, that is, one third of the patient groups., Results: We used the train and validation set to identify the best feature selection and classification model and applied it to the test set for each patient group. Classification yields for patients who underwent sorafenib monotherapy an accuracy of 75.51% and area under the curve (AUC) of 0.7576 (95% confidence interval [CI]: 0.6376-0.8776). For patients who underwent treatment with SIRT and sorafenib, results are accuracy = 78.00% and AUC = 0.8032 (95% CI: 0.6930-0.9134)., Conclusions: Parameters of radiomics-based analysis of the skeletal musculature and adipose tissue predict 1-year survival in patients with advanced HCC. The prognostic value of radiomics-based parameters was higher in patients who were treated with SIRT and sorafenib., (© 2023 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by Wiley Periodicals LLC.)
- Published
- 2023
- Full Text
- View/download PDF
66. The statistical analysis plan for the unification of treatments and interventions for tinnitus patients randomized clinical trial (UNITI-RCT).
- Author
-
Simoes JP, Schoisswohl S, Schlee W, Basso L, Bernal-Robledano A, Boecking B, Cima R, Denys S, Engelke M, Escalera-Balsera A, Gallego-Martinez A, Gallus S, Kikidis D, López-Escámez JA, Marcrum SC, Markatos N, Martin-Lagos J, Martinez-Martinez M, Mazurek B, Vassou E, Jarach CM, Mueller-Locatelli N, Neff P, Niemann U, Omar HK, Puga C, Schleicher M, Unnikrishnan V, Perez-Carpena P, Pryss R, Robles-Bolivar P, Rose M, Schecklmann M, Schiele T, Schobel J, Spiliopoulou M, Stark S, Vogel C, Wunder N, Zachou Z, and Langguth B
- Subjects
- Humans, Combined Modality Therapy, Anesthetics, Local, Europe, Tinnitus, Cognitive Behavioral Therapy
- Abstract
Background: Tinnitus is a leading cause of disease burden globally. Several therapeutic strategies are recommended in guidelines for the reduction of tinnitus distress; however, little is known about the potentially increased effectiveness of a combination of treatments and personalized treatments for each tinnitus patient., Methods: Within the Unification of Treatments and Interventions for Tinnitus Patients project, a multicenter, randomized clinical trial is conducted with the aim to compare the effectiveness of single treatments and combined treatments on tinnitus distress (UNITI-RCT). Five different tinnitus centers across Europe aim to treat chronic tinnitus patients with either cognitive behavioral therapy, sound therapy, structured counseling, or hearing aids alone, or with a combination of two of these treatments, resulting in four treatment arms with single treatment and six treatment arms with combinational treatment. This statistical analysis plan describes the statistical methods to be deployed in the UNITI-RCT., Discussion: The UNITI-RCT trial will provide important evidence about whether a combination of treatments is superior to a single treatment alone in the management of chronic tinnitus patients. This pre-specified statistical analysis plan details the methodology for the analysis of the UNITI trial results., Trial Registration: ClinicalTrials.gov NCT04663828 . The trial is ongoing. Date of registration: December 11, 2020. All patients that finished their treatment before 19 December 2022 are included in the main RCT analysis., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
67. Crystallization of heavy fermions via epitaxial strain in spinel LiV 2 O 4 thin film.
- Author
-
Niemann U, Wu YM, Oka R, Hirai D, Wang Y, Suyolcu YE, Kim M, van Aken PA, and Takagi H
- Abstract
The mixed-valent spinel LiV
2 O4 is known as the first oxide heavy-fermion system. There is a general consensus that a subtle interplay of charge, spin, and orbital degrees of freedom of correlated electrons plays a crucial role in the enhancement of quasi-particle mass, but the specific mechanism has remained yet elusive. A charge-ordering (CO) instability of V3+ and V4+ ions that is geometrically frustrated by the V pyrochlore sublattice from forming a long-range CO down to T = 0 K has been proposed as a prime candidate for the mechanism. Here, we uncover the hidden CO instability by applying epitaxial strain on single-crystalline LiV2 O4 thin films. We find a crystallization of heavy fermions in a LiV2 O4 film on MgO, where a charge-ordered insulator comprising of a stack of V3+ and V4+ layers along [001], the historical Verwey-type ordering, is stabilized by the in-plane tensile and out-of-plane compressive strains from the substrate. Our discovery of the [001] Verwey-type CO, together with previous realizations of a distinct [111] CO, evidence the close proximity of the heavy-fermion state to degenerate CO states mirroring the geometrical frustration of the V pyrochlore lattice, which supports the CO instability scenario for the mechanism behind the heavy-fermion formation.- Published
- 2023
- Full Text
- View/download PDF
68. GUCCI - Guided Cardiac Cohort Investigation of Blood Flow Data.
- Author
-
Meuschke M, Niemann U, Behrendt B, Gutberlet M, Preim B, and Lawonn K
- Subjects
- Humans, Cardiac Imaging Techniques, Computer Graphics, Hemodynamics
- Abstract
We present the framework GUCCI (Guided Cardiac Cohort Investigation), which provides a guided visual analytics workflow to analyze cohort-based measured blood flow data in the aorta. In the past, many specialized techniques have been developed for the visual exploration of such data sets for a better understanding of the influence of morphological and hemodynamic conditions on cardiovascular diseases. However, there is a lack of dedicated techniques that allow visual comparison of multiple data sets and defined cohorts, which is essential to characterize pathologies. GUCCI offers visual analytics techniques and novel visualization methods to guide the user through the comparison of predefined cohorts, such as healthy volunteers and patients with a pathologically altered aorta. The combination of overview and glyph-based depictions together with statistical cohort-specific information allows investigating differences and similarities of the time-dependent data. Our framework was evaluated in a qualitative user study with three radiologists specialized in cardiac imaging and two experts in medical blood flow visualization. They were able to discover cohort-specific characteristics, which supports the derivation of standard values as well as the assessment of pathology-related severity and the need for treatment.
- Published
- 2023
- Full Text
- View/download PDF
69. Juxtaposing Medical Centers Using Different Questionnaires Through Score Predictors.
- Author
-
Puga C, Schleicher M, Niemann U, Unnikrishnan V, Boecking B, Brueggemann P, Simoes J, Langguth B, Schlee W, Mazurek B, and Spiliopoulou M
- Abstract
Background: Chronic tinnitus is a clinically multidimensional phenomenon that entails audiological, psychological and somatosensory components. Previous research has demonstrated age and female gender as potential risk factors, although studies to this regard are heterogeneous. Moreover, whilst recent research has begun to identify clinical "phenotypes," little is known about differences in patient population profiles at geographically separated and specialized treatment centers. Identifying such differences might prevent potential biases in joint randomized controlled trials (RCTs) and allow for population-specific treatment adaptations., Method: Two German tinnitus treatment centers were compared regarding pre-treatment data distributions of their patient population bases. To identify overlapping as well as center-specific factors, juxtaposition-, similarity-, and meta-data-based methods were applied., Results: Between centers, significant differences emerged. One center demonstrated some predictive power of the patients of the other center with regard to questionnaire score after treatment, indicating similarities in treatment response across center populations. Furthermore, adherence to the completion of the questionnaires was found to be an important factor in predicting post-treatment data., Discussion: Differential age and gender distributions per center should be considered as regards RCT design and individualized treatment planning., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Puga, Schleicher, Niemann, Unnikrishnan, Boecking, Brueggemann, Simoes, Langguth, Schlee, Mazurek and Spiliopoulou.)
- Published
- 2022
- Full Text
- View/download PDF
70. Dimensions of Tinnitus-Related Distress.
- Author
-
Brueggemann P, Mebus W, Boecking B, Amarjargal N, Niemann U, Spiliopoulou M, Dobel C, Rose M, and Mazurek B
- Abstract
Objectives: (1) To determine which psychosocial aspects predict tinnitus-related distress in a large self-reported dataset of patients with chronic tinnitus, and (2) to identify underlying constructs by means of factor analysis., Methods: A cohort of 1958 patients of the Charité Tinnitus Center, Berlin completed a large questionnaire battery that comprised sociodemographic data, tinnitus-related distress, general psychological stress experience, emotional symptoms, and somatic complaints. To identify a construct of "tinnitus-related distress", significant predictive items were grouped using factor analysis., Results: For the prediction of tinnitus-related distress (linear regression model with R
2 = 0.7), depressive fatigue symptoms (concentration, sleep, rumination, joy decreased), the experience of emotional strain, somatization tendencies (pain experience, doctor contacts), and age appeared to play a role. The factor analysis revealed five factors: "stress", "pain experience", "fatigue", "autonomy", and low "educational level"., Conclusions: Tinnitus-related distress is predicted by psychological and sociodemographic indices. Relevant factors seem to be depressive exhaustion with somatic expressions such as sleep and concentration problems, somatization, general psychological stress, and reduced activity, in addition to higher age.- Published
- 2022
- Full Text
- View/download PDF
71. Assessing the difficulty of annotating medical data in crowdworking with help of experiments.
- Author
-
Rother A, Niemann U, Hielscher T, Völzke H, Ittermann T, and Spiliopoulou M
- Subjects
- Humans, Male, Female, Adult, Data Curation methods, Crowdsourcing methods
- Abstract
Background: As healthcare-related data proliferate, there is need to annotate them expertly for the purposes of personalized medicine. Crowdworking is an alternative to expensive expert labour. Annotation corresponds to diagnosis, so comparing unlabeled records to labeled ones seems more appropriate for crowdworkers without medical expertise. We modeled the comparison of a record to two other records as a triplet annotation task, and we conducted an experiment to investigate to what extend sensor-measured stress, task duration, uncertainty of the annotators and agreement among the annotators could predict annotation correctness., Materials and Methods: We conducted an annotation experiment on health data from a population-based study. The triplet annotation task was to decide whether an individual was more similar to a healthy one or to one with a given disorder. We used hepatic steatosis as example disorder, and described the individuals with 10 pre-selected characteristics related to this disorder. We recorded task duration, electro-dermal activity as stress indicator, and uncertainty as stated by the experiment participants (n = 29 non-experts and three experts) for 30 triplets. We built an Artificial Similarity-Based Annotator (ASBA) and compared its correctness and uncertainty to that of the experiment participants., Results: We found no correlation between correctness and either of stated uncertainty, stress and task duration. Annotator agreement has not been predictive either. Notably, for some tasks, annotators agreed unanimously on an incorrect annotation. When controlling for Triplet ID, we identified significant correlations, indicating that correctness, stress levels and annotation duration depend on the task itself. Average correctness among the experiment participants was slightly lower than achieved by ASBA. Triplet annotation turned to be similarly difficult for experts as for non-experts., Conclusion: Our lab experiment indicates that the task of triplet annotation must be prepared cautiously if delegated to crowdworkers. Neither certainty nor agreement among annotators should be assumed to imply correct annotation, because annotators may misjudge difficult tasks as easy and agree on incorrect annotations. Further research is needed to improve visualizations for complex tasks, to judiciously decide how much information to provide, Out-of-the-lab experiments in crowdworker setting are needed to identify appropriate designs of a human-annotation task, and to assess under what circumstances non-human annotation should be preferred., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2021
- Full Text
- View/download PDF
72. Towards a unification of treatments and interventions for tinnitus patients: The EU research and innovation action UNITI.
- Author
-
Schlee W, Schoisswohl S, Staudinger S, Schiller A, Lehner A, Langguth B, Schecklmann M, Simoes J, Neff P, Marcrum SC, Spiliopoulou M, Niemann U, Schleicher M, Unnikrishnan V, Puga C, Mulansky L, Pryss R, Vogel C, Allgaier J, Giannopoulou E, Birki K, Liakou K, Cima R, Vlaeyen JWS, Verhaert N, Ranson S, Mazurek B, Brueggemann P, Boecking B, Amarjargal N, Specht S, Stege A, Hummel M, Rose M, Oppel K, Dettling-Papargyris J, Lopez-Escamez JA, Amanat S, Gallego-Martinez A, Escalera-Balsera A, Espinosa-Sanchez JM, Garcia-Valdecasas J, Mata-Ferron M, Martin-Lagos J, Martinez-Martinez M, Martinez-Martinez MJ, Müller-Locatelli N, Perez-Carpena P, Alcazar-Beltran J, Hidalgo-Lopez L, Vellidou E, Sarafidis M, Katrakazas P, Kostaridou V, Koutsouris D, Manta R, Paraskevopoulos E, Haritou M, Elgoyhen AB, Goedhart H, Koller M, Shekhawat GS, Crump H, Hannemann R, Holfelder M, Oberholzer T, Vontas A, Trochidis I, Moumtzi V, Cederroth CR, Koloutsou K, Spanoudakis G, Basdekis I, Gallus S, Lugo A, Stival C, Borroni E, Markatos N, Bibas A, and Kikidis D
- Subjects
- Acoustic Stimulation, Cognitive Behavioral Therapy, Humans, Sound, Hearing Aids, Tinnitus therapy
- Abstract
Tinnitus is the perception of a phantom sound and the patient's reaction to it. Although much progress has been made, tinnitus remains a scientific and clinical enigma of high prevalence and high economic burden, with an estimated prevalence of 10%-20% among the adult population. The EU is funding a new collaborative project entitled "Unification of Treatments and Interventions for Tinnitus Patients" (UNITI, grant no. 848261) under its Horizon 2020 framework. The main goal of the UNITI project is to set the ground for a predictive computational model based on existing and longitudinal data attempting to address the question of which treatment or combination of treatments is optimal for a specific patient group based on certain parameters. Clinical, epidemiological, genetic and audiological data, including signals reflecting ear-brain communication, as well as patients' medical history, will be analyzed making use of existing databases. Predictive factors for different patient groups will be extracted and their prognostic relevance validated through a Randomized Clinical Trial (RCT) in which different patient groups will undergo a combination of tinnitus therapies targeting both auditory and central nervous systems. From a scientific point of view, the UNITI project can be summarized into the following research goals: (1) Analysis of existing data: Results of existing clinical studies will be analyzed to identify subgroups of patients with specific treatment responses and to identify systematic differences between the patient groups at the participating clinical centers. (2) Genetic and blood biomarker analysis: High throughput Whole Exome Sequencing (WES) will be performed in well-characterized chronic tinnitus cases, together with Proximity Extension Assays (PEA) for the identification of blood biomarkers for tinnitus. (3) RCT: A total of 500 patients will be recruited at five clinical centers across Europe comparing single treatments against combinational treatments. The four main treatments are Cognitive Behavioral Therapy (CBT), hearing aids, sound stimulation, and structured counseling. The consortium will also make use of e/m-health applications for the treatment and assessment of tinnitus. (4) Decision Support System: An innovative Decision Support System will be implemented, integrating all available parameters (epidemiological, clinical, audiometry, genetics, socioeconomic and medical history) to suggest specific examinations and the optimal intervention strategy based on the collected data. (5) Financial estimation analysis: A cost-effectiveness analysis for the respective interventions will be calculated to investigate the economic effects of the interventions based on quality-adjusted life years. In this paper, we will present the UNITI project, the scientific questions that it aims to address, the research consortium, and the organizational structure., (© 2021 Elsevier B.V. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
73. Phenotyping chronic tinnitus patients using self-report questionnaire data: cluster analysis and visual comparison.
- Author
-
Niemann U, Brueggemann P, Boecking B, Mebus W, Rose M, Spiliopoulou M, and Mazurek B
- Subjects
- Adaptation, Psychological physiology, Adolescent, Berlin, Chronic Disease, Cluster Analysis, Female, Humans, Male, Patients, Quality of Life, Self Report, Surveys and Questionnaires, Tinnitus pathology
- Abstract
Chronic tinnitus is a complex, multi-factorial symptom that requires careful assessment and management. Evidence-based therapeutic approaches involve audiological and psychological treatment components. However, not everyone benefits from treatment. The identification and characterisation of patient subgroups (or "phenotypes") may provide clinically relevant information. Due to the large number of assessment tools, data-driven methods appear to be promising. The acceptance of these empirical results can be further strengthened by a comprehensive visualisation. In this study, we used cluster analysis to identify distinct tinnitus phenotypes based on self-report questionnaire data and implemented a visualisation tool to explore phenotype idiosyncrasies. 1228 patients with chronic tinnitus from the Charité Tinnitus Center in Berlin were included. At baseline, each participant completed 14 questionnaires measuring tinnitus distress, -loudness, frequency and location, depressivity, perceived stress, quality of life, physical and mental health, pain perception, somatic symptom expression and coping attitudes. Four distinct patient phenotypes emerged from clustering: avoidant group (56.8%), psychosomatic group (14.1%), somatic group (15.2%), and distress group (13.9%). Radial bar- and line charts allowed for visual inspection and juxtaposition of major phenotype characteristics. The phenotypes differed in terms of clinical information including psychological symptoms, quality of life, coping attitudes, stress, tinnitus-related distress and pain, as well as socio-demographics. Our findings suggest that identifiable patient subgroups and their visualisation may allow for stratified treatment strategies and research designs.
- Published
- 2020
- Full Text
- View/download PDF
74. Combining visual analytics and case-based reasoning for rupture risk assessment of intracranial aneurysms.
- Author
-
Spitz L, Niemann U, Beuing O, Neyazi B, Sandalcioglu IE, Preim B, and Saalfeld S
- Subjects
- Algorithms, Computer Graphics, Databases, Factual, Decision Making, Humans, Models, Statistical, Surveys and Questionnaires, User-Computer Interface, Diagnosis, Computer-Assisted methods, Hemodynamics, Intracranial Aneurysm diagnostic imaging, Risk Assessment methods
- Abstract
Purpose: Medical case-based reasoning solves problems by applying experience gained from the outcome of previous treatments of the same kind. Particularly for complex treatment decisions, for example, incidentally found intracranial aneurysms (IAs), it can support the medical expert. IAs bear the risk of rupture and may lead to subarachnoidal hemorrhages. Treatment needs to be considered carefully, since it may entail unnecessary complications for IAs with low rupture risk. With a rupture risk prediction based on previous cases, the treatment decision can be supported., Methods: We present an interactive visual exploration tool for the case-based reasoning of IAs. In presence of a new aneurysm of interest, our application provides visual analytics techniques to identify the most similar cases with respect to morphology. The clinical expert can obtain the treatment, including the treatment outcome, for these cases and transfer it to the aneurysm of interest. Our application comprises a heatmap visualization, an adapted scatterplot matrix and fully or partially directed graphs with a circle- or force-directed layout to guide the interactive selection process. To fit the demands of clinical applications, we further integrated an interactive identification of outlier cases as well as an interactive attribute selection for the similarity calculation. A questionnaire evaluation with six trained physicians was used., Result: Our application allows for case-based reasoning of IAs based on a reference data set. Three classifiers summarize the rupture state of the most similar cases. Medical experts positively evaluated the application., Conclusion: Our case-based reasoning application combined with visual analytic techniques allows for representation of similar IAs to support the clinician. The graphical representation was rated very useful and provides visual information of the similarity of the k most similar cases.
- Published
- 2020
- Full Text
- View/download PDF
75. Gender-Specific Differences in Patients With Chronic Tinnitus-Baseline Characteristics and Treatment Effects.
- Author
-
Niemann U, Boecking B, Brueggemann P, Mazurek B, and Spiliopoulou M
- Abstract
Whilst some studies have identified gender-specific differences, there is no consensus about gender-specific determinants for prevalence rates or concomitant symptoms of chronic tinnitus such as depression or anxiety. However, gender-associated differences in psychological response profiles and coping strategies may differentially affect tinnitus chronification and treatment success rates. Thus, understanding gender-associated differences may facilitate a more detailed identification of symptom profiles, heighten treatment response rates, and help to create access for vulnerable populations that are potentially less visible in clinical settings. Our research questions are: RQ1: how do male and female tinnitus patients differ regarding tinnitus-related distress, depression severity, and treatment response, RQ2: to what extent are answers to questionnaires administered at baseline associated with gender, and RQ3: which baseline questionnaire items are associated with tinnitus distress, depression, and treatment response, while relating to one gender only? In this work, we present a data analysis workflow to investigate gender-specific differences in N = 1,628 patients with chronic tinnitus (828 female, 800 male) who completed a 7-day multimodal treatment encompassing cognitive behavioral therapy (CBT), physiotherapy, auditory attention training, and information counseling components. For this purpose, we extracted 181 variables from 7 self-report questionnaires on socio-demographics, tinnitus-related distress, tinnitus frequency, loudness, localization, and quality as well as physical and mental health status. Our workflow comprises (i) training machine learning models, (ii) a comprehensive evaluation including hyperparameter optimization, and (iii) post-learning steps to identify predictive variables. We found that female patients reported higher levels of tinnitus-related distress, depression and response to treatment (RQ1). Female patients indicated higher levels of tension, stress, and psychological coping strategies rates. By contrast, male patients reported higher levels of bodily pain associated with chronic tinnitus whilst judging their overall health as better (RQ2). Variables measuring depression, sleep problems, tinnitus frequency, and loudness were associated with tinnitus-related distress in both genders and indicators of mental health and subjective stress were found to be associated with depression in both genders (RQ3). Our results suggest that gender-associated differences in symptomatology and treatment response profiles suggest clinical and conceptual needs for differential diagnostics, case conceptualization and treatment pathways., (Copyright © 2020 Niemann, Boecking, Brueggemann, Mazurek and Spiliopoulou.)
- Published
- 2020
- Full Text
- View/download PDF
76. Plantar temperatures in stance position: A comparative study with healthy volunteers and diabetes patients diagnosed with sensoric neuropathy.
- Author
-
Niemann U, Spiliopoulou M, Malanowski J, Kellersmann J, Szczepanski T, Klose S, Dedonaki E, Walter I, Ming A, and Mertens PR
- Subjects
- Aged, Body Temperature, Female, Humans, Male, Middle Aged, Pressure, Standing Position, Diabetic Foot diagnosis, Foot pathology, Thermography methods
- Abstract
Background: Microcirculatory defects in diabetes are linked with neuropathy and the onset of diabetic foot syndrome. In this study we quantify pressure- and posture-dependent changes of plantar temperatures as a surrogate of tissue perfusion in healthy volunteers versus diabetes patients diagnosed with neuropathy in the absence of macroangiopathy., Methods: Healthy volunteers (n = 31) as well as patients with diabetes diagnosed with severe polyneuropathy (n = 30) were enrolled in a clinical study to test for plantar temperature changes in the feet during extended episodes of standing. These lasted between 5 and 20 min each over 95 min, in between the participants were asked to take a seated position for 5 min and release the pressure from the feet. Major macroangiopathy was excluded before study enrolment. Custom-made insoles harbored temperature and pressure sensors positioned at eight preselected positions for recording., Findings: In both subgroups a significant plantar temperature downshift occurred within 10 min of standing, which was especially detected during the initial 45 min of the study protocol. Comparisons between healthy volunteers and patients with diabetes revealed no differences in the magnitude of temperature downshifts during stance episodes. Pressure sensor recordings revealed that healthy volunteers intermittently released pressure during the longer stance episodes due to discomfort, whereas the patients with diabetes and polyneuropathy did not., Interpretation: Our findings demonstrate a tight plantar temperature regulation following pressure exposure. In patients with diabetes and peripheral sensoric neuropathy the temperature drop is similar to healthy volunteers. Potentially, prolonged stance periods resulting in less perfused plantar tissue may remain unrecognized with polyneuropathy, whereas discomfort develops in healthy controls., Funding: The study was supported by EFRE Förderung der Europäischen Union und Landesmittel des Ministeriums für Wirtschaft, Wissenschaft und Digitalisierung Sachsen-Anhalt (Vorhabennummer: ZS/2016/05/78,615 and ZS/2018/12/95,325). JK and PRM were supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - project ID 97,850,925 - SFB854, AM by the Chinese Scholarship Council (CSC)., Competing Interests: Declaration of Competing Interest SK and PRM filed a patent on sensor-equipped insoles: WO2012084814A1. TS is CEO at Thorsis Technologies GmbH., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
77. Development and internal validation of a depression severity prediction model for tinnitus patients based on questionnaire responses and socio-demographics.
- Author
-
Niemann U, Brueggemann P, Boecking B, Mazurek B, and Spiliopoulou M
- Subjects
- Adult, Depression diagnosis, Depression therapy, Female, Humans, Machine Learning, Male, Middle Aged, Prognosis, Severity of Illness Index, Socioeconomic Factors, Surveys and Questionnaires, Workflow, Depression epidemiology, Depression etiology, Disease Susceptibility, Tinnitus complications, Tinnitus epidemiology
- Abstract
Tinnitus is a complex condition that is associated with major psychological and economic impairments - partly through various comorbidities such as depression. Understanding the interaction between tinnitus and depression may thus improve either symptom cluster's prevention, diagnosis and treatment. In this study, we developed and validated a machine learning model to predict depression severity after outpatient therapy (T1) based on variables obtained before therapy (T0). 1,490 patients with chronic tinnitus (comorbid major depressive disorder: 52.2%) who completed a 7-day multimodal treatment encompassing tinnitus-specific components, cognitive behavioural therapy, physiotherapy and informational counselling were included. 185 variables were extracted from self-report questionnaires and socio-demographic data acquired at T0. We used 11 classification methods to train models that reliably separate between subclinical and clinical depression at T1 as measured by the general depression questionnaire. To ensure highly predictive and robust classifiers, we tuned algorithm hyperparameters in a 10-fold cross-validation scheme. To reduce model complexity and improve interpretability, we wrapped model training around an incremental feature selection mechanism that retained features that contributed to model prediction. We identified a LASSO model that included all 185 features to yield highest predictive performance (AUC = 0.87 ± 0.04). Through our feature selection wrapper, we identified a LASSO model with good trade-off between predictive performance and interpretability that used only 6 features (AUC = 0.85 ± 0.05). Thus, predictive machine learning models can lead to a better understanding of depression in tinnitus patients, and contribute to the selection of suitable therapeutic strategies and concise and valid questionnaire design for patients with chronic tinnitus with or without comorbid major depressive disorder.
- Published
- 2020
- Full Text
- View/download PDF
78. Tinnitus-related distress after multimodal treatment can be characterized using a key subset of baseline variables.
- Author
-
Niemann U, Boecking B, Brueggemann P, Mebus W, Mazurek B, and Spiliopoulou M
- Subjects
- Area Under Curve, Combined Modality Therapy, Female, Humans, Male, Middle Aged, Stress, Psychological etiology, Tinnitus psychology, Tinnitus therapy
- Abstract
Background: Chronic tinnitus is a complex condition that can be associated with considerable distress. Whilst cognitive-behavioral treatment (CBT) approaches have been shown to be effective, not all patients benefit from psychological or psychologically anchored multimodal therapies. Determinants of tinnitus-related distress thus provide valuable information about tinnitus characterization and therapy planning., Objective: The study aimed to develop machine learning models that use variables (or "features") obtained before treatment to characterize patients' tinnitus-related distress status after treatment. Whilst initially all available variables were considered for model training, the final model was required to achieve highest predictive performance using only a small number of features., Methods: 1,416 tinnitus patients (decompensated tinnitus: 32%) who completed a 7-day multimodal treatment encompassing tinnitus-specific components, CBT, physiotherapy and informational counseling were included in the analysis. At baseline, patients were assessed using 205 features from 10 questionnaires comprising sociodemographic and clinical information. A data-driven workflow was developed consisting of (a) an initial exploratory correlation analysis, (b) supervised machine learning to predict tinnitus-related distress after treatment (T1) using baseline data only (T0), and (c) post-hoc analysis of the best model to facilitate model inspection and understanding. Classification methods were embedded in a feature elimination wrapper that iteratively learned on features found to be important for the model in the preceding iteration, in order to keep the performance stable while successively reducing the model complexity. 10-fold cross-validation with area under the curve (AUC) as performance measure was implemented for model generalization error estimation., Results: The best machine learning classifier (gradient boosted trees) can predict tinnitus-related distress in T1 with AUC = 0.890 using 26 features. Subjectively perceived tinnitus-related impairment, depressivity, sleep problems, physical health-related impairments in quality of life, time spent to complete questionnaires and educational level exhibited a high attribution towards model prediction., Conclusions: Machine learning can reliably identify baseline features recorded prior to treatment commencement that characterize tinnitus-related distress after treatment. The identification of key features can contribute to an improved understanding of multifactorial contributors to tinnitus-related distress and thereon based multimodal treatment strategies., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2020
- Full Text
- View/download PDF
79. Comparative Clustering of Plantar Pressure Distributions in Diabetics with Polyneuropathy May Be Applied to Reveal Inappropriate Biomechanical Stress.
- Author
-
Niemann U, Spiliopoulou M, Szczepanski T, Samland F, Grützner J, Senk D, Ming A, Kellersmann J, Malanowski J, Klose S, and Mertens PR
- Subjects
- Biomechanical Phenomena, Case-Control Studies, Cluster Analysis, Female, Humans, Male, Middle Aged, Diabetic Neuropathies physiopathology, Foot physiopathology, Pressure, Stress, Mechanical
- Abstract
In diabetic patients, excessive peak plantar pressure has been identified as major risk factor for ulceration. Analyzing plantar pressure distributions potentially improves the identification of patients with a high risk for foot ulceration development. The goal of this study was to classify regional plantar pressure distributions. By means of a sensor-equipped insole, pressure recordings of healthy controls (n = 18) and diabetics with severe polyneuropathy (n = 25) were captured across eight foot regions. The study involved a controlled experimental protocol with multiple sessions, where a session contained several cycles of pressure exposure. Clustering was used to identify subgroups of study participants that are characterized by similar pressure distributions. For both analyzed groups, the number of clusters to best describe the pressure profiles was four. When both groups were combined, analysis again led to four distinct clusters. While three clusters did not separate between healthy and diabetic volunteers the fourth cluster was only represented by diabetics. Here the pressure distribution pattern is characterized by a focal point of pressure application on the forefoot and low pressure on the lateral region. Our data suggest that pressure clustering is a feasible means to identify inappropriate biomechanical plantar stress.
- Published
- 2016
- Full Text
- View/download PDF
80. 3D Regression Heat Map Analysis of Population Study Data.
- Author
-
Klemm P, Lawonn K, Glaßer S, Niemann U, Hegenscheid K, Völzke H, and Preim B
- Subjects
- Breast Neoplasms epidemiology, Fatty Liver, Female, Humans, Male, Middle Aged, Computational Biology methods, Computer Graphics, Epidemiologic Methods, Imaging, Three-Dimensional methods
- Abstract
Epidemiological studies comprise heterogeneous data about a subject group to define disease-specific risk factors. These data contain information (features) about a subject's lifestyle, medical status as well as medical image data. Statistical regression analysis is used to evaluate these features and to identify feature combinations indicating a disease (the target feature). We propose an analysis approach of epidemiological data sets by incorporating all features in an exhaustive regression-based analysis. This approach combines all independent features w.r.t. a target feature. It provides a visualization that reveals insights into the data by highlighting relationships. The 3D Regression Heat Map, a novel 3D visual encoding, acts as an overview of the whole data set. It shows all combinations of two to three independent features with a specific target disease. Slicing through the 3D Regression Heat Map allows for the detailed analysis of the underlying relationships. Expert knowledge about disease-specific hypotheses can be included into the analysis by adjusting the regression model formulas. Furthermore, the influences of features can be assessed using a difference view comparing different calculation results. We applied our 3D Regression Heat Map method to a hepatic steatosis data set to reproduce results from a data mining-driven analysis. A qualitative analysis was conducted on a breast density data set. We were able to derive new hypotheses about relations between breast density and breast lesions with breast cancer. With the 3D Regression Heat Map, we present a visual overview of epidemiological data that allows for the first time an interactive regression-based analysis of large feature sets with respect to a disease.
- Published
- 2016
- Full Text
- View/download PDF
81. [Treatment options in popliteal aneurysm repair].
- Author
-
Niemann U, Hoffmann W, Trassl M, and Imdahl A
- Subjects
- Aneurysm diagnosis, Angiography, Combined Modality Therapy, Imaging, Three-Dimensional, Tomography, X-Ray Computed, Aneurysm therapy, Blood Vessel Prosthesis Implantation, Popliteal Artery pathology, Popliteal Artery surgery, Stents, Thrombolytic Therapy
- Published
- 2013
82. [Acute abdomen: diagnostic approach].
- Author
-
Niemann U, Imdahl A, and Richter M
- Subjects
- Abdomen, Acute diagnosis, Abdomen, Acute surgery, Angiography, Diagnosis, Differential, Gangrene, Humans, Ileus diagnosis, Ileus surgery, Intestinal Perforation diagnosis, Intestinal Perforation surgery, Intestine, Small blood supply, Intestine, Small pathology, Ischemia diagnosis, Ischemia surgery, Medical History Taking, Mesenteric Vascular Occlusion diagnosis, Mesenteric Vascular Occlusion surgery, Necrosis, Physical Examination methods, Pneumoperitoneum diagnosis, Pneumoperitoneum etiology, Prognosis, Tomography, X-Ray Computed, Abdomen, Acute etiology
- Published
- 2011
83. [Not Available].
- Author
-
Niemann U
- Published
- 2011
- Full Text
- View/download PDF
84. [Differential diagnosis of right abdominal pain].
- Author
-
Niemann U, Tabatabai K, Jordan U, and Imdahl A
- Subjects
- Abdominal Pain etiology, Acute Disease, Diagnosis, Differential, Female, Humans, Laparoscopy, Magnetic Resonance Imaging, Male, Middle Aged, Palpation, Physical Examination, Pregnancy, Radiography, Abdominal, Tomography, X-Ray Computed, Abdomen, Acute diagnosis, Abdominal Pain diagnosis, Appendicitis diagnosis, Diverticulitis, Colonic diagnosis, Genital Diseases, Female diagnosis, Intestinal Perforation diagnosis, Sigmoid Diseases diagnosis
- Published
- 2009
85. [Peranal bleeding].
- Author
-
Niemann U, Jordan U, and Imdahl A
- Subjects
- Angiodysplasia diagnosis, Angiodysplasia therapy, Colorectal Neoplasms diagnosis, Colorectal Neoplasms therapy, Diagnosis, Differential, Diverticulitis, Colonic diagnosis, Diverticulitis, Colonic therapy, Gastrointestinal Hemorrhage diagnosis, Gastrointestinal Hemorrhage therapy, Gastroscopy, Hemorrhoids diagnosis, Hemorrhoids therapy, Humans, Male, Middle Aged, Colonoscopy, Gastrointestinal Hemorrhage etiology
- Published
- 2008
- Full Text
- View/download PDF
86. [Sporadical extraperitoneal desmoid tumors--review and report on 4 cases].
- Author
-
Spree E, Niemann U, and Wenisch H
- Subjects
- Abdominal Neoplasms pathology, Abdominal Neoplasms radiotherapy, Abdominal Wall pathology, Abdominal Wall surgery, Adult, Combined Modality Therapy, Female, Fibromatosis, Aggressive pathology, Fibromatosis, Aggressive radiotherapy, Follow-Up Studies, Humans, Neoplasm Recurrence, Local pathology, Radiotherapy, Adjuvant, Reoperation, Thoracic Neoplasms pathology, Thoracic Neoplasms radiotherapy, Abdominal Neoplasms surgery, Fibromatosis, Aggressive surgery, Neoplasm Recurrence, Local radiotherapy, Neoplasm Recurrence, Local surgery, Thoracic Neoplasms surgery
- Abstract
Introduction: Desmoid tumors are very rare mesenchymal tumors with a partially aggressive growth pattern and high relapse rates. Without metastases, they are classified as semi-malignant tumours. The treatment of this neoplasia is discussed controversially. Up to now, there exists no broad consensus on the treatment regimes. Traditionally, the primary radical surgical resection is often preferred. This might be combined with an (neo-)adjuvant radiation therapy. Recently an increasing importance of radiotherapy has been described. Several studies favour radiotherapy as the single form of treatment. Furthermore several medication regimes have been described in the literature., Case Reports: We report the follow-up of 4 patients who were treated for desmoid tumours. In 2 cases surgery was the primary treatment. After R0-resection and adjuvant radiation therapy, one of the patients developed 7 relapses. In another patient, 5 relapses were observed after surgical therapy., Discussion: Therapeutic guidelines with broad acceptance do not exist up to now due to missing data of prospective studies with sufficient case numbers. In our opinion wide surgical resection should be performed in primary occurring cases with resectable tumours. On account of the previous experiences, it can be concluded that therapy of primary non respectable or recurrent desmoid tumours is not only a domain of a surgical approach. At present an adequate treatment should be planned interdisciplinary by surgeons, radiation therapists and oncologists. For generally accepted guidelines for this rare disease, general therapeutic options based on prospectively randomised studies have to be elaborated.
- Published
- 2005
- Full Text
- View/download PDF
87. Structural domains required for channel function of the mouse transient receptor potential protein homologue TRP1beta.
- Author
-
Engelke M, Friedrich O, Budde P, Schäfer C, Niemann U, Zitt C, Jüngling E, Rocks O, Lückhoff A, and Frey J
- Subjects
- Animals, Calcium Channels genetics, Calcium Channels metabolism, Cell Line, Dimerization, Gene Deletion, Humans, Membrane Potentials physiology, Mice, Mutation, Protein Conformation, Protein Structure, Tertiary, Repetitive Sequences, Amino Acid, TRPC Cation Channels, Transfection, Two-Hybrid System Techniques, Calcium Channels chemistry
- Abstract
Transient receptor potential proteins (TRP) are supposed to participate in the formation of store-operated Ca(2+) influx channels by co-assembly. However, little is known which domains facilitate the interaction of subunits. Contribution of the N-terminal coiled-coil domain and ankyrin-like repeats and the putative pore region of the mouse TRP1beta (mTRP1beta) variant to the formation of functional cation channels were analyzed following overexpression in HEK293 (human embryonic kidney) cells. MTRP1beta expressing cells exhibited enhanced Ca(2+) influx and enhanced whole-cell membrane currents compared to mTRP1beta deletion mutants. Using a yeast two-hybrid assay only the coiled-coil domain facilitated homodimerization of the N-terminus. These results suggest that the N-terminus of mTRP1beta is required for structural organization thus forming functional channels.
- Published
- 2002
- Full Text
- View/download PDF
88. 25 years experience of the surgical treatment of phaeochromocytoma.
- Author
-
Niemann U, Hiller W, and Behrend M
- Subjects
- Adolescent, Adrenal Gland Neoplasms diagnosis, Adrenal Gland Neoplasms epidemiology, Adrenalectomy adverse effects, Adult, Age Distribution, Aged, Cohort Studies, Female, Follow-Up Studies, Germany epidemiology, Humans, Male, Middle Aged, Pheochromocytoma diagnosis, Pheochromocytoma epidemiology, Postoperative Complications mortality, Retrospective Studies, Risk Assessment, Severity of Illness Index, Sex Distribution, Survival Rate, Treatment Outcome, Adrenal Gland Neoplasms surgery, Adrenalectomy methods, Pheochromocytoma surgery
- Abstract
Objective: To assess the outcome of the surgical treatment of patients who had adrenalectomy for phaeochromocytoma., Design: Retrospective clinical study., Settings: University hospital, Germany., Subjects: 87 consecutive patients with phaeochromocytoma who were operated on., Interventions: 29 flank and 58 transabdominal adrenalectomies between 1974 and 2000., Results: The mean tumour diameter was 5 cm (range 2-13), and the mean weight 91 g (range 7-550). The postoperative hospital stay was 11 days. The flank incision entailed the shortest operating time (95 minutes). Two of the phaeochromocytomas were malignant. There were two wound infections but no deaths. With a correct selection of patients, a flank incision is safe. Endoscopic retroperitoneal adrenalectomies should be preferred.
- Published
- 2002
- Full Text
- View/download PDF
89. Immunohistological localization of tenascin-C in the developing and regenerating retinotectal system of two amphibian species.
- Author
-
Becker T, Becker CG, Niemann U, Naujoks-Manteuffel C, Bartsch U, Schachner M, and Roth G
- Subjects
- Animals, Antibodies immunology, Blotting, Western, Immunohistochemistry, Rana esculenta, Extracellular Matrix immunology, Optic Nerve immunology, Retina immunology, Tenascin immunology
- Abstract
The expression pattern of the extracellular matrix molecule tenascin-C was investigated in the retinotectal system of the frog Discoglossus pictus and the salamander Pleurodeles waltl during development and optic nerve regeneration in the adult. In both species, the retina was devoid of tenascin-C immunoreactivity at all ages studied. During development, tenascin-C was distributed in a gradient in the optic nerve, with the highest immunoreactivity in the eye near part of the optic nerve. The myelin-associated glycoprotein was distributed in a gradient with opposite polarity. In Discoglossus, but not Pleurodeles, tenascin-C was detected in the anterior chiasm. In the tectum of both species, tenascin-C was observed in deep cellular and fiber layers but not in the layers receiving optic fibers or proliferative zones. The distribution patterns of tenascin-C were the same during development and in the adult, except for a disappearance of the molecule from the intraocular part of the optic nerve. After lesioning the optic nerve of adult animals, tenascin-C was strongly reexpressed in the intraocular part of the optic nerve but was only weakly upregulated in the distal optic nerve stump. In contrast, a chondroitin sulfate epitope was strongly upregulated in the distal optic nerve stump. These observations suggest that during development, tenascin-C serves as an attenuating barrier for myelinating cells in the optic nerve and contributes to the guidance of growing retinal ganglion cell axons. Due to its sustained expression in the adult, tenascin-C may have similar functions during regeneration of the lesioned adult retinotectal system.
- Published
- 1995
- Full Text
- View/download PDF
90. Microglial cells in the brain of Pleurodeles waltl (Urodela, Salamandridae) after wallerian degeneration in the primary visual system using Bandeiraea simplicifolia isolectin B4-cytochemistry.
- Author
-
Naujoks-Manteuffel C and Niemann U
- Subjects
- Animals, Denervation, Immunohistochemistry, Lectins, Nerve Regeneration, Optic Nerve cytology, Retinal Ganglion Cells physiology, Wallerian Degeneration, Brain cytology, Microglia cytology, Plant Lectins, Pleurodeles anatomy & histology, Visual Pathways cytology
- Abstract
In the brain of the salamander Pleurodeles waltl, microglial cells were investigated cytochemically with isolectin B4 (IB4) of Bandeiraea simplicifolia after optic nerve transection and during subsequent regeneration. Double-labeling with an antibody directed against the glial fibrillary acidic protein of astrocytes revealed no immunoreactivity in microglial cells and confirmed the absence of non-radial, free astroglial cells in the tectum. After two days, IB4-labeled microglial cells began to populate the rostral parts of the primary visual system. The origin of these early vimentin-immunoreactive microglial cells seemed to be mainly IB4-labeled cells in a perivascular position and meningeal macrophages. After 12 days, microglial cells infiltrated the tectum in four layers: one in the ependyma, one in the outermost periventricular grey, and two in the degenerating visual neuropil where activated microglial cells displayed a ramified morphology. After 3 weeks, microglial cells accumulated within the degenerating neuropil while reducing their processes. After 7 weeks, the number of microglial cells was still increased on the affected side. The subarachnoid space above the neuropil where regenerating retinal afferents arrived was filled with IB4-labeled macrophages. Only very few microglial cells were seen in co-existence with Müller cells in the lesioned and intact retinae, whereas microglial cells and macrophages were IB4-labeled in the optic nerve head and at the ora serrata.
- Published
- 1994
- Full Text
- View/download PDF
91. Amphibian-specific regulation of polysialic acid and the neural cell adhesion molecule in development and regeneration of the retinotectal system of the salamander Pleurodeles waltl.
- Author
-
Becker T, Becker CG, Niemann U, Naujoks-Manteuffel C, Gerardy-Schahn R, and Roth G
- Subjects
- Animals, Antibodies, Monoclonal immunology, Antibodies, Monoclonal metabolism, Blotting, Western, Immunohistochemistry, Larva, Metamorphosis, Biological physiology, Nerve Crush, Optic Nerve growth & development, Optic Nerve metabolism, Optic Nerve physiology, Retina growth & development, Retina metabolism, Retinal Ganglion Cells metabolism, Superior Colliculi growth & development, Superior Colliculi metabolism, Cell Adhesion Molecules, Neuronal biosynthesis, Nerve Regeneration physiology, Pleurodeles physiology, Retina physiology, Sialic Acids biosynthesis, Superior Colliculi physiology
- Abstract
Antibodies specific to the neural cell adhesion molecule (NCAM-total), the 180 x 10(3) M(r) component of NCAM (NCAM-180) and polysialic acid (PSA) were used in immunohistochemistry and Western blots to detect the spatiotemporal dynamics of these molecules in development and regeneration of the retinotectal system of Pleurodeles waltl. NCAM-total and NCAM-180 are continuously expressed in the retina, optic nerve, and tectum of the developing and adult salamander. This is also found for the 140 x 10(3) M(r) component of NCAM in Western blots of the retina. In the larval retina, PSA is present in the inner plexiform layer (IPL) and a few cells in all nuclear layers. At metamorphosis, PSA expression in the retina strongly increases in the layer of cone photoreceptor somata. Several cells in the inner nuclear layer and Müller cell processes also begin to express PSA. This pattern persists into adulthood. The optic nerve and the tectum are strongly PSA-immunoreactive throughout development. In the adult optic nerve and optic fiber pathway in the brain, PSA expression is selectively downregulated. In the crush-lesioned adult optic nerve, regenerating fibers are NCAM-180-positive but PSA-negative. This demonstrates a molecular difference between growing nerve fibers of Pleurodeles in development and in regeneration. PSA regulation is closely correlated with metamorphosis, thus suggesting that PSA expression may be under hormonal control. Some aspects of PSA and NCAM isoform expression patterns in the retinotectal system of salamanders differ considerably from that of other vertebrates. The sustained expression of NCAM isoforms in adult salamanders might be due to secondary simplification (paedomorphosis).
- Published
- 1993
- Full Text
- View/download PDF
92. Exteroceptive silent periods of temporalis muscle activity: correlation with neuropsychological findings.
- Author
-
Wallasch TM, Niemann U, Kropp P, and Weinschütz T
- Subjects
- Adolescent, Adult, Aged, Electromyography, Humans, Middle Aged, Neuropsychological Tests, Reaction Time physiology, Headache physiopathology, Headache psychology, Temporal Muscle physiopathology
- Abstract
The latency and duration of the early (ES 1) and late (ES 2) exteroceptive silent period of temporalis muscle activity were determined in 51 neurological patients. We investigated whether these electrophysiological parameters correlated with neuropsychological variables of the patients using standardized scores for personality index, state of well-being and physical symptoms. There were no correlations between personality traits and the electrophysiological parameters, while we found significant correlations between the duration of ES 2 and momentary psychological and physical well-being variables. Moreover, the score of the momentary well-being item 'general feeling of well-being' was demonstrated to moderate significantly the ES 2 duration (P = 0.018). Therefore, neuropsychological factors prove to be of great relevance to the exteroceptive silent periods of temporalis muscle activity.
- Published
- 1993
- Full Text
- View/download PDF
93. The "temporalis-inhibitory reflex" in post-lumbar puncture headache.
- Author
-
Wallasch TM, Niemann U, and Strenge H
- Subjects
- Adolescent, Adult, Aged, Electric Stimulation, Electromyography, Female, Headache physiopathology, Humans, Intracranial Pressure, Male, Middle Aged, Muscle Contraction, Prospective Studies, Temporal Muscle innervation, Trigeminal Nerve physiology, Brain Stem physiology, Headache etiology, Reflex physiology, Spinal Puncture adverse effects, Temporal Muscle physiopathology
- Abstract
Nausea and rigidity of the neck muscles, typical symptoms of post-lumbar puncture syndrome (PPS), may also be found in patients suffering from chronic headache of the tension-type. A decreased duration of the late suppression period of temporal muscle activity indicating a central disturbance of pericranial muscle control, can be observed in these patients. We have studied the temporalis-inhibitory reflex in 47 neurological inpatients requiring lumbar puncture. There were no significant differences of latencies or durations of temporalis silent periods between patients with and without PPS before, and 48 h following, lumbar puncture.
- Published
- 1992
94. [The management of nervous disturbances with psychoverlan].
- Author
-
Blumenbach A, Küver G, and Niemann U
- Subjects
- Adolescent, Adult, Aged, Child, Child, Preschool, Drug Combinations, Humans, Infant, Middle Aged, Neurotic Disorders drug therapy, Stress, Physiological drug therapy, Bromine therapeutic use, Glutamates therapeutic use, Magnesium therapeutic use, Psychophysiologic Disorders drug therapy, Tranquilizing Agents therapeutic use
- Published
- 1974
95. [Morphology of the tubal drainage angle of the human uterus and of the pars intramuralis of the tuba uterina].
- Author
-
Philipp E and Niemann U
- Subjects
- Endometrium anatomy & histology, Fallopian Tube Neoplasms pathology, Fallopian Tubes pathology, Female, Humans, Precancerous Conditions pathology, Uterine Neoplasms pathology, Fallopian Tubes anatomy & histology, Uterus anatomy & histology
- Abstract
The morphology of the pars intramuralis of the fallopian tube has been histological examined in 500 uteri which were exstirpated in the Department of Gynaecology and Obstetrics of the University of Kiel in the years of 1972 to 1973. It was found that the interstitial pars of the endometrium changes regularly during the menstrual cycle. In the same way the endometrium in the interstitial part of the tubal canal suffers from an atrophy if patients were treated with gestagens. The adenomatous hyperplasie or the polypes of the endometrium which are often found near the utero-tubal junction are to be considered as the matrix of the carcinoma of the endometrium; continuous changes between the adenomatous hyperplasie and the carcinoma of the endometrium can be observed. The frequency of precancers near the utero-tubal junction underlines the demand for an accurate curettage in this region of the cavum uteri. The histological examination of the region of the utero-tubal junction after the extirpation of the uterus is absolutely necessary and has to be generally to be asked for.
- Published
- 1979
96. [Rare diagnosis in traumatic surgery: adamantinom of the tibia (author's transl)].
- Author
-
Fuchs G and Niemann U
- Subjects
- Adult, Ameloblastoma surgery, Bone Transplantation, Female, Humans, Transplantation, Homologous, Ameloblastoma diagnosis, Tibia
- Published
- 1980
97. [The origin of cytoplasmic inclusions in the endothelium of the aorta and large arteries].
- Author
-
SINAPIUS D and NIEMANN U
- Subjects
- Humans, Aorta pathology, Arteries, Endothelium, Inclusion Bodies
- Published
- 1959
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.