Influence of Power-Weighted Center of Echo Signal Within Window Function on Local Strain Rate Distribution in Left Ventricular Wall.

OBJECTIVE: The deviation of the power-weighted center of the echo signal from the geometric center within the velocity estimation window for calculating strain rate (SR) causes an estimation error. This study aimed to confirm whether an erroneous multilayer pattern in the SR distribution of the left ventricular wall could be corrected by considering the power-weighted center of the echo signal. METHODS: The SR distributions were measured locally in the transmural direction around the pre-ejection and early diastolic phases in healthy volunteers. The estimation error related to the power-weighted center of the echo signal was corrected using a previously proposed method, and the effectiveness of the correction was confirmed based on the accuracy of the estimated myocardial displacement. RESULTS: The SR distribution in early diastole was observed as multilayers of low- and high-amplitude negative SRs. However, this multilayer pattern disappeared after correction. In the pre-ejection phase, multilayers of positive and negative SRs were observed in the SR distributions with and without correction. This correction was sufficiently effective in accurately tracking the local peak of the echo signal. CONCLUSION: The multilayer pattern of low- and high-amplitude positive or negative SRs is caused by estimation errors related to the power-weighted center of the echo signal. The multilayer pattern of positive and negative SRs might not be caused by these errors and might relate to the actual change in myocardial thickness because the estimation errors do not convert the negative (positive) SR to positive (negative) in a homogeneous negative (positive) SR distribution.

Appropriate Window Function and Window Length in Multifrequency Velocity Estimator for Rapid Motion and Locality of Layered Myocardium.

The heart wall has a multilayered structure and moves rapidly during ejection and rapid filling periods. Local strain rate (SR) measurements of each myocardial layer can contribute to accurate and sensitive evaluations of myocardial function. However, ultrasound-based velocity estimators using a single-frequency phase difference cannot realize these measurements owing to insufficient maximum detectable velocity, which is limited by a quadrature frequency. We previously proposed a velocity estimator using multifrequency phase differences to improve the maximum detectable velocity. However, the improvement is affected by a spatial discrete Fourier transform (DFT) window length that represents the locality of the velocity estimation. In this article, we theoretically describe that shortening the window increases the interference between different frequency components and decreases the maximum detectable velocity. The tradeoff between the maximum detectable velocity and the window length was confirmed through simulations and a water-tank experiment. Under the tradeoff, the Hanning window, which was used in previous studies, is not always appropriate for the local measurement of the velocity, which sometimes exceeds 100 mm [Formula: see text] depending on the subject, direction of the ultrasound beam to the heart wall, and cardiac periods. In the in vivo measurement with the short window, the Tukey window with a large flat part that has a high-frequency resolution and ameliorates the discontinuity at both edges of the windowed signal was appropriate to measure the maximum velocity. This study offers the potential for local measurements of each myocardial layer using the multifrequency velocity estimator with the appropriate window function and window length.

Strain Rate Distribution in Layered Myocardium Measured Using Local Velocity Estimator with Multifrequency Phase Differences.

Measurement of the myocardial strain rate (SR), with high spatial resolution, is useful in evaluation of the transmurality of myocardial infarction. As the SR distribution is calculated using velocities observed at multiple positions in the heart wall, it is necessary to estimate the local velocity to measure SR distribution. In the present study, our previously proposed local velocity estimator, with multifrequency phase differences, was used to measure SR distribution in the heart wall. The SR distribution measured with the proposed local velocity estimator revealed alternate layers of contraction and relaxation, which were not measured with the conventional velocity estimator with spatial averaging. The reproducibility of the SR distributions was confirmed in three consecutive heartbeats with three subjects. High-spatial-resolution SR measurement with the proposed local velocity estimator will allow myocardial layer-specific analysis in the transmural direction.

Multifrequency Phased Tracking Method for Estimating Velocity in Heart Wall.

Local high-accuracy velocity estimation is important for the ultrasound-based evaluation of regional myocardial function. The ultrasound phase difference at the center frequency of the transmitted signal has been conventionally used for velocity estimation. In the conventional method, spatial averaging is necessary owing to the frequency-dependent attenuation and interference of backscattered waves. Here, we propose a method for suppressing these effects using multifrequency phase differences. The resulting improvement in velocity estimation in the heart wall was validated by in vivo experiments. In the conventional method, the velocity waveform exhibits spike-like changes. The velocity waveform estimated using the proposed method did not exhibit such changes. Because the proposed method estimates myocardium velocity without spatial averaging, it can be used for measuring heart wall dynamics involving thickness changes.

High Remission Rate with Infliximab and Plant-Based Diet as First-Line (IPF) Therapy for Severe Ulcerative Colitis: Single-Group Trial.

INTRODUCTION: About one-third of patients with severe ulcerative colitis (UC) do not respond to corticosteroid therapy and receive rescue therapy with infliximab or cyclosporine. Up to 20% of such patients fail to respond to rescue therapy and undergo colectomy. OBJECTIVE: We investigated the outcomes of infliximab and a plant-based diet (PBD) as first-line therapy for severe UC. METHODS: Patients with severe UC defined by the Truelove and Witts criteria were admitted and given standard induction therapy with infliximab (5.0 mg/kg-7.5 mg/kg) at 0, 2, and 6 weeks. Additionally, they received a PBD. The primary endpoint was remission or colectomy in the induction phase and 1 year after discharge. Secondary endpoints were changes in inflammatory markers in the induction phase and the PBD score at baseline and follow-up. A higher PBD score indicates greater adherence to a PBD. RESULTS: Infliximab and PBD as first-line therapy was administered in 17 cases. The remission rate was 76% (13/17), and the colectomy rate was 6% (1/17) in the induction phase. C-reactive protein values and the erythrocyte sedimentation rate significantly decreased at week 6 from 9.42 mg/dL to 0.33 mg/dL and from 59 to 17 mm/h, respectively (p < 0.0001). At 1-year follow-up, the cumulative relapse rate was 25%, and there were no additional colectomy cases. Mean PBD scores of 27.7 at 1 year and 23.8 at 4 years were significantly higher than baseline scores of 8.3 and 9.9, respectively (p < 0.0001 and p = 0.0391). CONCLUSION: This new first-line therapy for severe UC demonstrated a higher remission rate and lower colectomy rate than with the current modality.

Relapse Prevention by Plant-Based Diet Incorporated into Induction Therapy for Ulcerative Colitis: A Single-Group Trial.

CONTEXT: No known previous study has focused on plant-based diet (PBD) to prevent relapse of ulcerative colitis (UC) except our previous educational hospitalization study. OBJECTIVE: To describe the relapse rate in a large case series of UC after incorporation of PBD into induction therapy. DESIGN: All patients with UC between 2003 and 2017 were admitted for induction therapy. Patients receiving educational hospitalization or treated with infliximab were excluded. A lacto-ovo-semivegetarian diet (PBD) together with medication prescribed according to UC guidelines was provided during hospitalization. MAIN OUTCOME MEASURES: The primary endpoint was relapse during follow-up. The secondary endpoint was change over time in the plant-based diet score (PBDS), which evaluated adherence to the PBD. RESULTS: Ninety-two cases were studied, of which 51 were initial episodes and 41 were relapses. Cases varied in severity (31 mild, 48 moderate, 13 severe) and extent (15 proctitis, 22 left-sided colitis, 55 extensive colitis). More severe cases existed among the relapse cases than among the initial episode cases. Cumulative relapse rates at 1- and 5-year follow-up (Kaplan-Meier analysis) were 14% and 27%, respectively, for the initial episode cases, and 36% and 53%, respectively, for relapse cases. At long-term follow-up (6 years 4 months), PBDS was significantly higher than baseline PBDS (p < 0.0001). CONCLUSION: Relapse rates in UC after induction therapy with PBD were far lower than those previously reported with conventional therapy. Adherence to PBD was significantly higher than baseline even at 6-year follow-up. We conclude PBD is effective for preventing UC relapse.(Study identification no.: UMIN000019061: Registration: www.umin.ac.jp).

Comparing guiding track requirements for myosin- and kinesin-powered molecular shuttles.

The design of nanoscale transport systems utilizing motor proteins as engines has advanced rapidly. Here, actin/myosin- and microtubule/kinesin-based molecular shuttles are compared with respect to their requirements for track designs. To this end, the trajectory persistence length of actin filaments gliding on myosin-coated surfaces has been experimentally determined to be equal to 8.8 +/- 2 microm. This measurement complements an earlier determination of the trajectory persistence length of microtubules gliding on kinesin-coated surfaces and enables a comparison of the accessible track designs for kinesin and myosin motor-powered systems. Despite the 200-fold smaller stiffness of actin filaments compared to that of microtubules, the dimensions of myosin tracks for actin filaments have to be quite similar to the dimensions of kinesin tracks for microtubules (radii larger than 200 nm and widths smaller than 0.9 microm compared to 600 nm and 19 microm). The difference in gliding speed is shown to require additional consideration in the design of track modules.