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Derek J Dosdall Kang-An Cheng Jian Huang J Scott Allison James D Allred William M Smith Raymond E Ideker 《Heart rhythm》2007,4(6):758-765
BACKGROUND: Earliest recorded postshock myocardial activations in pigs originate in the subepicardium of the apex and lateral free wall of the left ventricle (LV) 30-90 ms after the shock. OBJECTIVE: The purpose of this study was to determine whether the Purkinje system is a candidate for the source of postshock activations by performing endocardial and transmural postshock activation mapping. METHODS: In five pigs, 32 plunge needles with 12 electrodes (1-mm spacing) were inserted into the LV apex and lateral free wall. Up to 70 plunge needles with six electrodes (2-mm spacing) were spread throughout the remainder of the LV, while 9-12 plunge needles with four electrodes (2-mm spacing) were inserted into the right ventricle. A basket catheter with 32 bipolar recording sites was inserted into the LV. Defibrillation-threshold (DFT)-level shocks were delivered during 10 episodes of electrically induced ventricular fibrillation. Electrograms of postshock activation cycles were analyzed for Purkinje and myocardial activations. RESULTS: Purkinje activations were recorded before local myocardial activation in 9% of basket electrograms and in 15% of plunge needles during the first postshock activation cycle. Purkinje activations were identified during the first and subsequent several postshock activation cycles in at least one basket and one needle electrogram in 96% and 98% of defibrillation episodes, respectively. CONCLUSIONS: The Purkinje system is active during the early postshock activation cycles after DFT-level shocks. Further studies are required to determine whether activation initiates in the Purkinje system or whether it is activated by the myocardium or by Purkinje-myocardial junctional cells. 相似文献
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Previous studies examining the association between social comparison processes and body image dissatisfaction have yielded inconsistent findings. This study examined whether such discrepancies are due to either the use of identical comparison targets for all subjects or variability in body mass. Specifically, 216 subjects were randomly assigned to one of three experimental conditions: self-generated upward comparison group, self-generated downward comparison group, or control group. Dependent variables were measures of body image. Results indicated that increasing body mass and trait comparison tendencies were associated with increased body dissatisfaction. However, the experimental manipulation did not affect body image ratings. Results suggest that social comparison processes may operate similarly over a range of body mass index (BMI) values. 相似文献
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Uroscopy in the 21st century: high-field NMR spectroscopy 总被引:1,自引:1,他引:0
Neild GH; Foxall PJ; Lindon JC; Holmes EC; Nicholson JK 《Nephrology, dialysis, transplantation》1997,12(3):404-417
From the experiments described, it can be seen that there are different
research approaches that can be taken and these are summarized in Table 1.
Whereas much scientific research is principally hypothesis led, there
remains, nevertheless, an important place for exploratory research. High
resolution NMR can measure, directly and simultaneously, a wide range of
endogenous metabolites in biological fluids and has the unique capability
of providing structural information on the metabolites detected. It has
proved to be a powerful research tool with which to study inherited
metabolic diseases, renal disease, drug metabolism, and toxicity, and can
be used to monitor the effects of drug therapy. For instance, by using a
library of experimental toxins one can map the metabolic profile of
site-specific nephron injury. With this approach in man one could
eventually take an unknown disease such as Balkan nephropathy and predict
the initial site of tubular injury, the mode of injury and therefore the
kind of toxin capable of producing that injury. NMR spectroscopic
techniques are still advancing rapidly, with ever increasing sensitivity
and sophistication of NMR pulse sequences to enhance structural elucidation
in complex mixtures. Given the advances in directly coupled HPLC-NMR and
even HPLC-NMR-mass spectroscopy it is likely that these technologies in
conjunction with pattern recognition will make major contribution to our
understanding of renal processes and provide new diagnostic insights in the
21st century.
相似文献
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This study investigated preferential encoding of threat material in subjects with posttraumatic stress disorder (PTSD) with a modified dot-probe paradigm. This paradigm indexes attentional bias by measuring response latency to name neutral target words that are presented adjacent to or distant from threat words. Motor vehicle accident survivors with PTSD (n = 15), subclinical PTSD (n = 15), and low anxiety (n = 15) were required to name target words that were presented either adjacent to or distant from strong threat, mild threat, positive, and neutral words. PTSD subjects named targets faster when they were in close proximity to mild threat words. Results suggested that PTSD subjects' attention was drawn to the mild threat stimuli and are discussed in the context of network models of PTSD. 相似文献
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Leukotriene B4 (LTB4) and the protein kinase C activator, 4-beta-phorbol dibutyrate (PDBu), both induced a pronounced and concentration-dependent stimulation of hydrogen peroxide (H2O2) generation by purified guinea pig peritoneal eosinophils in the concentration range 1 nM-1 microM. The LTB4 response was inhibited competitively by the specific LTB4 receptor antagonist, U-75302, with a KB of 25 nM, while the concentration-response curves for both stimuli were shifted rightwards (3.8-fold and 2.8-fold for LTB4 and PDBu, respectively) by the competitive protein kinase C inhibitor, 1-O-hexadecyl-2-O-methylglycerol at a concentration of 300 microM. LTB4 appears, therefore, to induce respiratory burst in eosinophils via a receptor-mediated mechanism involving protein kinase C. 相似文献