Background-Atrial stretch causes remodeling that predisposes to atrial fibrillation. We tested the hypothesis that peaks in left atrial (LA) wall stress are associated with focal remodeling. Methods and Results-Nineteen patients underwent LA mapping before catheter ablation for persistent atrial fibrillation.Finite Element Analysis was used to predict wall stress distribution based on LA geometry from CT. The relationship was assessed between wall stress and (1) electrogram voltage and (2) complex fractionated atrial electrograms (CFAE), using CFAE mean (the mean interval between deflections). Wall stress varied widely within atria and between subjects (median, 36 kPa; interquartile range, 26 -51 kP). Peaks in wall stress (Ն90th percentile) were common at the pulmonary vein (PV) ostia (93%), the appendage ridge (100%), the high posterior wall (84%), and the anterior wall and septal regions (42-84%). Electrogram voltage showed an inverse relationship across quartiles for wall stress (19% difference across quartiles, Pϭ0.016). There was no effect on CFAE mean across quartiles of wall stress. Receiver operating characteristic analysis showed high wall stress was associated with low voltage (ie, Ͻ0.5 mV) and electrical scar (ie, Ͻ0.05 mV; both PϽ0.0001) and with absence of CFAE (ie, CFAE mean Ͻ120 ms; PϽ0.0001). However, peaks in wall stress and CFAE were found at 88% of PV ostia. Conclusions-Peaks in wall stress were associated with areas of low voltage, suggestive of focal remodeling. Although peaks in wall stress were not associated with LA CFAE, the PV ostia may respond differently. (Circ Arrhythm Electrophysiol. 2012;5:351-360.)
Liquid−Liquid equilibria (LLE) have been measured for five
ternary and two multicomponent mixtures
containing cyclohexane, benzene, toluene, p-xylene,
tetraethylene glycol (TTEG), and water at 60 °C and
140 °C. A new UNIFAC group was defined, and its parameters were
determined from the experimental
data. The calculated values are in good agreement with the
experimental and literature data with
sufficient accuracy for the engineering design.
We studied the expression of procollagen type I, matrix metalloproteinase 1 (MMP1) and tissue inhibitor of metalloproteinase 1 (TIMP-1) by immunohistochemistry in human patellar tendinosis tissues and healthy patellar tendons. In situ gelatin zymography was used to detect collagenolytic activities. The productions of MMP1, TIMP1 and gelatinolytic activities were compared in cell cultures from tendinosis samples and controls. Tendinosis tissues and cultures showed an increase in the expression level of MMP1 and a decrease in that of TIMP1, a condition favoring collagen degradation. Gelatinolytic activities in tendinosis tissues and cultures were elevated. Collagenolysis is a striking feature in patellar tendinosis.
To compare the efficacy of ultra-high and conventional mono-b-value DWI for glioma grading, in 109 pathologically confirmed glioma patients, ultra-high apparent diffusion coefficient (ADCuh)was calculated using a tri-exponential mode, distributed diffusion coefficients (DDCs) and α values were calculated using a stretched-exponential model, and conventional ADC values were calculated using a mono-exponential model. The efficacy and reliability of parameters for grading gliomas were investigated using receiver operating characteristic (ROC) curve and intra-class correlation (ICC) analyses, respectively. The ADCuh values differed (P < 0.001) between low-grade gliomas (LGGs; 0.436 ×10−3 mm2/sec) and high-grade gliomas (HGGs; 0.285 × 10−3 mm2/sec). DDC, a and various conventional ADC values were smaller in HGGs (all P ≤ 0.001, vs. LGGs). The ADCuh parameter achieved the highest diagnostic efficacy with an area under curve (AUC) of 0.993, 92.9% sensitivity and 98.8% specificity for glioma grading at a cutoff value of 0.362×10−3 mm2/sec. ADCuh measurement appears to be an easy-to-perform technique with good reproducibility (ICC = 0.9391, P < 0.001). The ADCuh value based in a tri-exponential model exhibited greater efficacy and reliability than other DWI parameters, making it a promising technique for glioma grading.
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