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排序方式: 共有961条查询结果,搜索用时 15 毫秒
81.
Annika Juergens Hendrik Pels Sabine Rogowski Klaus Fliessbach Axel Glasmacher Andreas Engert Marcel Reiser Volker Diehl Marlies Vogt‐Schaden Gerlinde Egerer Gabriele Schackert Heinz Reichmann Frank Kroschinsky Udo Bode Ulrich Herrlinger Michael Linnebank Martina Deckert Rolf Fimmers Ingo G. H. Schmidt‐Wolf Uwe Schlegel 《Annals of neurology》2010,67(2):182-189
82.
Jan‐Rüdiger Schüre Manoj Shrestha Stella Breuer Ralf Deichmann Elke Hattingen Marlies Wagner Ulrich Pilatus 《NMR in biomedicine》2019,32(11)
The pH value is a potential physiological marker for clinical diagnosis as it is altered in pathologies such as tumors. While intracellular pH can be measured noninvasively via phosphorus spectroscopy (31P MRSI), Amide Proton Transfer‐Chemical Exchange Saturation Transfer (APT‐CEST) MRI has been suggested as an alternative method for pH quantification. To assess the suitability of APT‐CEST contrast for pH quantification, two approaches (magnetization transfer ratio asymmetry [MTRasym] and Lorentzian difference analysis [LDA]) for analyzing the Z‐spectrum have been correlated with pH values obtained by 31P MRSI. Fourteen patients with glioblastoma and 12 healthy controls were included. In contrast to MTRasym, the LDA is modeling the direct water saturation and the semi‐solid magnetization transfer, allowing a separate evaluation of the aliphatic nuclear Overhauser effect and the APT‐CEST. The results of our study show that the pH values obtained by 31P MRSI correspond well with both methods describing the APT‐CEST contrast. Two‐sample t‐test showed significant differences in MTRasym, LDA and pH obtained by 31P MRSI for regions of interest in glioblastoma, contralateral control areas and normal appearing white matter (P < 0.001). A slightly improved correlation between the amide signal and pH was found after performing LDA (r = 0.78) compared with MTRasym (r = 0.70). While both methods can be used to monitor pH changes, the LDA approach appears to be better suited. 相似文献
83.
Marlies E. C. ELFRINK Annemarie A. SCHULLER Jaap S. J. VEERKAMP Jan H. G. POORTERMAN Henriette A. MOLL Bob M. Ten CATE 《International journal of paediatric dentistry / the British Paedodontic Society [and] the International Association of Dentistry for Children》2010,20(2):151-157
International Journal of Paediatric Dentistry 2010; 20: 151–157 Background. Caries is still a prevalent condition in 5‐year‐old children. At present, knowledge regarding some aetiological factors, like deciduous molar hypomineralization (DMH), is limited. Aim. To investigate aetiological factors both directly and indirectly associated with caries in second primary molars. Design. Of 974 children invited to participate in the study, 386 children were examined clinically with visual detection of caries. Only carious lesions determined to have reached the dentine were recorded. Information about tooth brushing frequency, education level of the mother, and country of birth of mother and child, was collected by means of a multiple‐choice questionnaire. Parents of 452 children filled in the questionnaire. Complete clinical and questionnaire data were available for 242 children. Statistical analysis of the effect of the independent variables was undertaken using the Pearson’s chi‐squared test. Results. Deciduous molar hypomineralization (P = 0.02) and the country of birth of the mother (P < 0.001) were positively associated with caries prevalence. Conclusions. Deciduous molar hypomineralization and the country of birth of the mother play a role in the prevalence of dental caries. These aetiological factors associated with childhood dental caries need to be investigated further in longitudinal clinical trials. 相似文献
84.
Zöllner Johann Philipp Paule Esther Wagner Marlies Freiman Thomas M. Rosenow Felix Strzelczyk Adam 《Zeitschrift für Epileptologie》2020,33(1):15-21
Clinical Epileptology - Temporale Enzephalozelen sind bisher nur in wenigen Fällen als Ursache von symptomatischen Epilepsien beschrieben worden. Zunehmende Beschreibungen in Fallserien weisen... 相似文献
85.
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87.
Joerg Magerkurth Steffen Volz Marlies Wagner Alina Jurcoane Sandra Anti Alexander Seiler Elke Hattingen Ralf Deichmann 《Magnetic resonance in medicine》2011,66(4):989-997
Numerous clinical and research applications for quantitative mapping of the effective transverse relaxation time T*2 have been described. Subject motion can severely deteriorate the quality and accuracy of results. A correction method for T*2 maps acquired with multi‐slice multiple gradient echo FLASH imaging is presented, based on acquisition repetition with reduced spatial resolution (and consequently reduced acquisition time) and weighted averaging of both data sets, choosing weighting factors individually for each k‐space line to reduce the influence of motion. In detail, the procedure is based on the fact that motion artifacts reduce the correlation between acquired and exponentially fitted data. A target data set is constructed in image space, choosing the data yielding best correlation from the two acquired data sets. The k‐space representation of the target is subsequently approximated as linear combination of original raw data, yielding the required weighting factors. As this method only requires a single acquisition repetition with reduced spatial resolution, it can be employed on any clinical system offering a suitable sequence with export of modulus and phase images. Experimental results show that the method works well for sparse motion, but fails for strong motion affecting the same k‐space lines in both acquisitions. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc. 相似文献
88.
Marlies De Boeck Sonia Lardau Jean-Pierre Buchet Micheline Kirsch-Volders Dominique Lison 《癌变.畸变.突变》2001,13(4)
An increased lung cancer risk is associated with occupational exposure to mixtures of cobalt metal and metallic carbide particles, but when exposure is to cobalt metal alone. The current TLV-TWA was established without consideration of carcinogenicity data. The present study was designed to assess whether an increased cancer risk can be detected in workers currently exposed on average to the TLV-TWA (20 μg/m3). 相似文献
89.
Problem: Non-response and non-usable response were found in population surveys on valuation of health states. If non-response is selective regarding valuations, then generalization of the resulting values to the whole survey population is not permitted. This could limit the use of empirical utility values in resource allocation in health care. Methods: Response behaviour of a sample of 1400 from the Dutch general population to the mailed EuroQolc-questionnaire was analyzed by four methods. I. Phoning resolute non-respondents; II. comparison of zip code characteristics of respondents and non-respondents (because individual data on background characteristics were not available for the non-respondents); III. analysis of response over time (wave-analysis); IV: comparison of background variables of successful (less than two valuations missing) and unsuccessful respondents, combined with analysis of the effect of these background variables on valuations. Results: No indications for selective non-response were found, although the phenomenon appeared hard to investigate. The successful response came from a slightly younger and better educated subsample. However, a general influence of age and educational level on valuations could not be shown. This finding is consistent with the literature. Conclusion: Although the existence of selective non-response cannot be excluded, its relevance can be considered to be small. This finding is encouraging for the use of empirical utility values in allocative decisions. 相似文献
90.
van der Welle ME Roelofs JG Op Den Camp HJ Lamers LP 《Environmental toxicology and chemistry / SETAC》2007,26(4):686-694
Metal pollution can be a serious threat to ecosystems at a global scale. Although the bioavailability of potentially toxic metals is determined by many biotic and abiotic factors, including pH and redox potential, total metal concentrations in the soil are used widely to assess or predict toxicity. In the present study we tested the effect of desiccation of soils differing in acidification potential and total heavy metal contamination on the growth and metal uptake of three typical, common wetland species: Caltha palustris, Juncus effusus, and Rumex hydrolapathum. We found that plant growth in wet soils mainly was determined by nutrient availability, though in dry soils the combined effects of acidification and increased metal availability prevailed. Metal uptake under anaerobic conditions was best predicted by the acidification potential (sediment S/[Ca + Mg] ratio), not by total metal concentrations. We propose that this is related to radial oxygen loss by wetland plant roots, which leads to acidification of the rhizosphere. Under aerobic conditions, plant metal uptake was best predicted by the amount of CaCl2-extractable metals. We conclude that total metal concentrations are not suitable for predicting bioavailability and that the above diagnostic parameters will provide insight into biogeochemical processes involved in toxicity assessment and soil policy. 相似文献