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61.
Liehr M Haueisen J Goernig M Seidel P Nenonen J Katila T 《Annals of biomedical engineering》2005,33(2):240-247
Recent studies reported differential information in human magnetocardiogram and in electrocardiogram. Vortex currents have been discussed as a possible source of this divergence. With the help of physical phantom experiments, we quantified the influence of active vortex currents on the strength of electric and magnetic signals, and we tested the ability of standard source localization algorithms to reconstruct vortex currents. The active vortex currents were modeled by a set of twelve single current dipoles arranged in a circle and mounted inside a phantom that resembles a human torso. Magnetic and electric data were recorded simultaneously while the dipoles were switched on stepwise one after the other. The magnetic signal strength increased continuously for an increasing number of dipoles switched on. The electric signal strength increased up to a semicircle and decreased thereafter. Source reconstruction with unconstrained focal source models performed well for a single dipole only (less than 3-mm localization error). Minimum norm source reconstruction yielded reasonable results only for a few of the dipole configurations. In conclusion active vortex currents might explain, at least in part, the difference between magnetically and electrically acquired data, but improved source models are required for their reconstruction. 相似文献
62.
The Role of APO-1-Mediated Apoptosis in the Immune System 总被引:12,自引:0,他引:12
63.
Site-independent prognostic value of chromosome 9q loss in primary gastrointestinal stromal tumours 总被引:5,自引:0,他引:5
Gunawan B Schulten HJ von Heydebreck A Schmidt B Enders C Höer J Langer C Schüler P Schindler CG Kuhlgatz J Füzesi L 《The Journal of pathology》2004,202(4):421-429
Although the significance of tumour site for estimating malignant potential in gastrointestinal stromal tumours (GISTs) has recently been recognized, site-specific genetic patterns have not to date been defined. This study examined 52 c-kit-positive primary GISTs (with a mean follow-up of 42.3 months in 51 cases) from three different locations (35 gastric, 12 small intestinal, and five colorectal) using comparative genomic hybridization (CGH). In general, tumour site correlated with key prognostic factors, including tumour size, mitotic rate, proliferative activity, and probable malignant potential. Furthermore, several DNA copy number changes showed a site-dependent pattern. These included losses at 14q (gastric 83%, intestinal 35%; p = 0.001), losses at 22q (gastric 46%, intestinal 82%; p = 0.02), losses at 1p (gastric 23%, intestinal 88%; p = 1 x 10(-5)), losses at 15q (gastric 14%, intestinal 59%; p = 0.002), losses at 9q (gastric 14%, intestinal 53%; p = 0.006), and gains at 5p (gastric 11%, intestinal 53%; p = 0.002). These data demonstrate strong site-dependent genetic heterogeneity in GISTs that may form a basis for subclassification. Prognostic evaluation of DNA copy number changes identified losses at 9q as a site-independent prognostic marker associated with shorter disease-free survival (p = 0.03) and overall survival (p = 0.002). Furthermore, 9q loss also appeared to carry prognostic value in predicting overall survival for patients with advanced or progressive GISTs (p = 0.003). 相似文献
64.
APO-1(CD95)-dependent and -independent antigen receptor-induced apoptosis in human T and B cell lines 总被引:3,自引:0,他引:3
Peter Marcus E.; Dhein Jens; Ehret Andreas; Hellbardt Stefan; Walczak Henning; Moldenhauer Gerhard; Krammer Peter H. 《International immunology》1995,7(11):1873-1884
Certain B and T cell lines respond to activation signals, e.g.through the antigen receptor, by undergoing apoptotlc cell death.In T cells it has been recently shown that TCR-mediated apoptosisinvolves APO-1/Fas (CD95) receptor-ligand interaction. To investigatewhether the TCR-CD3 complex can trigger alternative apoptosispathways we generated subclones of the T cell line Jurkat whichwere completely resistant towards APO-1-mediated apoptosis.These JurkatR cells differed phenotypically from sensitive parentalJurkatS cells only by the lack of APO-1 protein expression.Although JurkatR cells responded normally to anti-CD3 stimulationby expression of APO-1 ligand they failed to undergo anti-CD3-inducedapoptosis. Thus, in Jurkat cells APO-1 -mediated apoptosis wasthe main, and might be the only, mechanism for anti-CD3-inducedcell death. However, BL-60 B cells, highly sensitive to anti-IgM-inducedapoptosis, did not use the APO-1 receptor-ligand system becausethey failed to express APO-1 ligand mRNA. Taken together, ourresults suggest that malignant T and B cell lines may use APO-1receptor-ligand-dependent and -independent antigen receptor-inducedapoptosis pathways respectively. Similarly, differential pathwaysmay be used by T and B cell subsets. 相似文献
65.
Carlo Cervia Jakob Nilsson Yves Zurbuchen Alan Valaperti Jens Schreiner Aline Wolfensberger Miro E. Raeber Sarah Adamo Sebastian Weigang Marc Emmenegger Sara Hasler Philipp P. Bosshard Elena De Cecco Esther Bächli Alain Rudiger Melina Stüssi-Helbling Lars C. Huber Annelies S. Zinkernagel Onur Boyman 《The Journal of allergy and clinical immunology》2021,147(2):545-557.e9
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66.
Przybylski GK Wanzeck J Verschuren MC Van Dongen JJ Serke S Schmidt CA 《Immunology》2003,108(1):16-23
Within the human T-cell receptor delta (TCRD) gene we have identified a new cluster of seven delta recombining elements (deltaRec2.1-2.7), located 2.6-5.2 kilobases downstream of the Vdelta2 gene segment. The deltaRec2 elements are isolated recombining signal sequences (RSS), which were shown to rearrange with the Ddelta3 and Jdelta1 segments of the TCRD gene as well as with the psiJalpha of the TCRA gene. Rearrangements involving the deltaRec2 elements were found in all peripheral blood (PB) samples from 10 healthy individuals, although their frequency was about 100-fold lower than that of classical deltaRec rearrangements. The total frequency of deltaRec2 rearrangements was lower in PB T lymphocytes, as compared with thymocytes, suggesting that they are deleted during T-cell development. The decrease of the frequency of the deltaRec2-Ddelta3 rearrangements was most prominent: 11 times lower in PB T lymphocytes than in thymocytes. Since the deltaRec2-Jdelta1 rearrangements contained the Ddelta3 segment in the junctional region, we assume that they are derived from the deltaRec2-Ddelta3 rearrangements. In contrast, the majority of deltaRec2-psiJalpha rearrangements did not contain the Ddelta3 segment, indicating that they are single step rearrangements. The deltaRec2-Jdelta1 and deltaRec2-psiJalpha rearrangements seem to be T-lineage specific, but the deltaRec2-Ddelta3 rearrangements were also found at very low frequencies in B lymphocytes and natural killer cells. Our results suggest that deltaRec2 rearrangements are transient steps in the recombinatorial process of the TCRAD locus and are probably deleted by subsequent Valpha-Jalpha rearrangements. We hypothesize, that in a similar manner to the classical deltaRec rearrangements, the deltaRec2 rearrangements might also contribute to T-cell differentiation towards the TCR-alphabeta lineage. 相似文献
67.
Update on Pneumocystis carinii f. sp. hominis Typing Based on Nucleotide Sequence Variations in Internal Transcribed Spacer Regions of rRNA Genes 总被引:6,自引:0,他引:6
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Chao-Hung Lee Jannik Helweg-Larsen Xing Tang Shaoling Jin Baozheng Li Marilyn S. Bartlett Jang-Jih Lu Bettina Lundgren Jens D. Lundgren Mats Olsson Sebastian B. Lucas Patricia Roux Antonietta Cargnel Chiara Atzori Olga Matos James W. Smith 《Journal of clinical microbiology》1998,36(3):734-741
Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study. 相似文献
68.
Functional mapping of color processing by magnetic resonance imaging of responses to selective P- and M-pathway stimulation 总被引:2,自引:0,他引:2
Andreas Kleinschmidt Barry B. Lee Martin Requardt Jens Frahm 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1996,110(2):279-288
Magnetic resonance imaging sensitized to activity-related changes in cerebral blood oxygenation was performed to map responses to selective stimulation of the parvo- and magnocellular visual pathways in calcarine and adjacent ventral occipital cortex of human subjects. In a repetitive stimulation protocol isoluminant chromatic or isochromatic luminance modulation was alternated with steady light of the same mean chromaticity and luminance as a reference condition. While no significant effects were observed for diffuse luminance modulation, two consistent cortical foci responded to isoluminant chromatic stimulation. A strong response was obtained in calcarine cortex at both 2 and 10 Hz, and even for selective S-cone stimulation. A second weaker colorsensitive response was seen bilaterally in the collateral sulcus. Thus, the data not only confirm color-sensitive activation in the collateral sulcus elicited in previous studies by selective cognitive tasks, but additionally demonstrate color-sensitive activation in primary visual cortex. With stimuli defined according to electrophysiological response properties of early visual processing stages, this study complements phenomenological or cognitive approaches in functional mapping of the human visual system. 相似文献
69.
Merkler D Boretius S Stadelmann C Ernsting T Michaelis T Frahm J Brück W 《NMR in biomedicine》2005,18(6):395-403
Although magnetic resonance imaging (MRI) represents the most sensitive tool for the detection of white matter abnormalities in patients with multiple sclerosis (MS), the heterogeneity of MS placques severely hampers the elucidation of specific pathophysiological processes. In order to identify putative MRI markers for de- and remyelination, we employed the cuprizone mouse model which leads to a selective and reversible demyelination of the corpus callosum with little or no axonal damage. Apart from histopathology, animals were studied with high-resolution three-dimensional MRI in vivo using multiple contrasts. While individual MRI findings significantly correlated with electron microscopy, the differentiation of regions with normal, demyelinated or remyelinated white matter by one contrast alone was less specific than by histology or electron microscopy. However, an accurate MRI prediction of the in vivo myelin status was achieved by a discriminant function analysis using a combination of T1, T2 and magnetization transfer contrast. With a correct assignment of 95% of all animals examined, the procedure will allow for the survey of new therapeutic approaches aiming at improved remyelination. 相似文献
70.
Krustrup P Söderlund K Mohr M González-Alonso J Bangsbo J 《Pflügers Archiv : European journal of physiology》2004,449(1):56-65
To investigate recruitment of slow-twitch (ST) and fast-twitch (FT) muscle fibres, as well as the involvement of the various quadriceps femoris muscle portions during repeated, intense, one-legged knee-extensor exercise, 12 healthy male subjects performed two 3-min exercise bouts at ~110% maximum thigh O2 consumption (EX1 and EX2) separated by 6 min rest. Single-fibre metabolites were determined in successive muscle biopsies obtained from the vastus lateralis muscle (n=6) and intra-muscular temperatures were continuously measured at six quadriceps muscle sites (n=6). Creatine phosphate (CP) had decreased (P<0.05) by 27, 73 and 88% in ST fibres and 25, 71 and 89% in FT fibres after 15 and 180 s of EX1 and after 180 s of EX2, respectively. CP was below resting mean–1 SD in 15, 46, 84 and 100% of the ST fibres and 9, 48, 85 and 100% of the FT fibres at rest, after 15 and 180 s of EX1 and after 180 s of EX2, respectively. A significant muscle temperature increase (Tm) occurred within 2–4 s at all quadriceps muscle sites. Tm varied less than 10% between sites during EX1, but was 23% higher (P<0.05) in the vastus lateralis than in the rectus femoris muscle during EX2. Tm in the vastus lateralis was 101 and 109% of the mean quadriceps value during EX1 and EX2, respectively. We conclude that both fibre types and all quadriceps muscle portions are recruited at the onset of intense knee-extensor exercise, that essentially all quadriceps muscle fibres are activated during repeated intense exercise and that metabolic measurements in the vastus lateralis muscle provide a good indication of the whole-quadriceps muscle metabolism during repeated, intense, one-legged knee-extensor exercise. 相似文献