scholarly journals The partitioning of nanoparticles to endothelium or interstitium during ultrasound-microbubble-targeted delivery depends on peak-negative pressure

2015 ◽  
Vol 17 (8) ◽  
Author(s):  
Y.-H. Hsiang ◽  
J. Song ◽  
R. J. Price
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Leela Goel ◽  
Huaiyu Wu ◽  
Bohua Zhang ◽  
Jinwook Kim ◽  
Paul A. Dayton ◽  
...  

AbstractOne major challenge in current microbubble (MB) and tissue plasminogen activator (tPA)-mediated sonothrombolysis techniques is effectively treating retracted blood clots, owing to the high density and low porosity of retracted clots. Nanodroplets (NDs) have the potential to enhance retracted clot lysis owing to their small size and ability to penetrate into retracted clots to enhance drug delivery. For the first time, we demonstrate that a sub-megahertz, forward-viewing intravascular (FVI) transducer can be used for ND-mediated sonothrombolysis, in vitro. In this study, we determined the minimum peak negative pressure to induce cavitation with low-boiling point phase change nanodroplets and clot lysis. We then compared nanodroplet mediated sonothrombolysis to MB and tPA mediate techniques. The clot lysis as a percent mass decrease in retracted clots was 9 ± 8%, 9 ± 5%, 16 ± 5%, 14 ± 9%, 17 ± 9%, 30 ± 8%, and 40 ± 9% for the control group, tPA alone, tPA + US, MB + US, MB + tPA + US, ND + US, and ND + tPA + US groups, respectively. In retracted blood clots, combined ND- and tPA-mediated sonothrombolysis was able to significantly enhance retracted clot lysis compared with traditional MB and tPA-mediated sonothrombolysis techniques. Combined nanodroplet with tPA-mediated sonothrombolysis may provide a feasible strategy for safely treating retracted clots.


2020 ◽  
Vol 48 (11) ◽  
pp. 2726-2732 ◽  
Author(s):  
Hunter W. Storaci ◽  
Hajime Utsunomiya ◽  
Bryson R. Kemler ◽  
Samuel I. Rosenberg ◽  
Grant J. Dornan ◽  
...  

Background: The acetabular labrum has been found to provide a significant contribution to the distractive stability of the hip. However, the influence of labral height on hip suction seal biomechanics is not known. Hypothesis: The smaller height of acetabular labrum is associated with decreased distractive stability. Study Design: Descriptive laboratory study. Methods: A total of 23 fresh-frozen cadaveric hemipelvises were used in this study. Hips with acetabular dysplasia or femoroacetabular impingement–related bony morphologic features, intra-articular pathology, or no measurable suction seal were excluded. Before testing, each specimen’s hip capsule was removed, a pressure sensor was placed intra-articularly, and the hip was fixed in a heated saline bath. Labral size was measured by use of a digital caliper. Maximum distraction force, distance to suction seal rupture, and peak negative pressure were recorded while the hip underwent distraction at a rate of 0.5 mm/s. Correlations between factors were analyzed using the Spearman rho, and differences between groups were detected using Mann-Whitney U test. Results: Of 23 hips, 12 satisfied inclusion criteria. The maximum distraction force and peak negative pressure were significantly correlated ( R = −0.83; P = .001). Labral height was largely correlated with all suction seal parameters (maximum distraction force, R = 0.69, P = .013; distance to suction seal rupture, R = 0.55, P = .063; peak negative pressure, R = −0.62, P = .031). Labral height less than 6 mm was observed in 5 hips, with a mean height of 6.48 mm (SD, 2.65 mm; range, 2.62-11.90 mm; 95% CI, 4.80-8.17 mm). Compared with the 7 hips with larger labra (>6 mm), the hips with smaller labra had significantly shorter distance to suction seal rupture (median, 2.3 vs 7.2 mm; P = .010) and significantly decreased peak negative pressure (median, −59.3 vs −66.9 kPa; P = .048). Conclusion: Smaller height (<6 mm) of the acetabular labrum was significantly associated with decreased distance to suction seal rupture and decreased peak negative pressure. A new strategy to increase the size of the labrum, such as labral augmentation, could be justified for patients with smaller labra in order to optimize the hip suction seal. Clinical Relevance: The height of the acetabular labrum is correlated with hip suction seal biomechanics. Further studies are required to identify the clinical effects of labral height on hip stability.


2021 ◽  
Author(s):  
Farah Hussein

Ultrasound and microbubble (USMB) enhances intracellular uptake through membrane disruption and endocytosis. This study investigates USMB effects on the molecular release incells through membrane-disruption and exocytosis. Retinal pigmented epithelial (RPE) cells were loaded with Alexa 647-transferrin (Tfn) to mark recycling endosomes, LAMP-1 antibody was used to mark lysosomes, GFP-transfected RPE cells were used to mark cytoplasm, and 7-AAD was used to assess cell viability. USMB exposure was done at 570kPa peak negative pressure for 1min. The mean fluorescent intensities (MFI) of markers were measured using flow cytometry. USMB induced the release of 19% and 67% of GFP from the cytoplasm in viable and non-viable cells respectively. LAMP-1 antibody MFI increased by 50% and 15-folds in viable and non-viable cells indicating USMB induced release from lysosomes. Furthermore, Tfn release from recycling endosomes increased by 22% only in viable cells. In conclusion, USMB enhances the molecular release from cytoplasm, lysosomes, and recycling endosomes


1988 ◽  
Vol 64 (2) ◽  
pp. 511-520 ◽  
Author(s):  
R. Sanii ◽  
M. Younes

Inspiratory duration (TI) increases during inspiratory resistive loading in conscious humans. To ascertain whether this response is related to the temporal pattern of pressure perturbation (reaching a peak in early or midinspiration and declining subsequently) we compared the response of nine normal subjects to a usual resistor (narrow tube, RES) with their response when mouth pressure was reduced in a sinusoidal fashion during inspiration (SIN). Whereas the negative pressure pattern was similar with both loads (peak negative pressure near midinspiration), there was no relation between pressure and flow in the case of sinusoidal loading. Each experiment consisted of two loading periods, 4 min each, and three unloaded periods, also 4 min each, bracketing the periods of loading. The order of RES and SIN was randomized. TI during loading was compared with the average TI of the preceding and following unloaded periods. TI increased 0.74 +/- 0.12 and 0.27 +/- 0.05 (SE) s during RES and SIN, respectively (P less than 0.01). We conclude that the temporal pattern of pressure change during resistance breathing plays a small role in mediating the TI prolongation. Coupling between flow and the pressure perturbation appears to be an important determinant of TI prolongation.


2021 ◽  
Author(s):  
Dong-Guk Paeng

A laser-generated carbon nanotube (CNT) transducer has been known to generate a shock wave with large amplitude for lasting sub-microseconds without producing heat. This laser-generated CNT transducer has never been applied to transcranial focused ultrasound (tcFUS) applications. Based on preliminary observation of the Evans blue leaked in the brain tissue of a rat after sonication of the shock wave by a CNT transducer, BBB opening of the rat by the shock wave from the CNT transducer was tried to confirm without damage of vessels. However, peak negative pressure was saturated to -9 MPa which is not enough for cavitation even with all trials of different fabrication processes such as coating methods of the PDMS layer, CNT-PDMS composite layers, backing materials, and CNT solutions. These results and discussion and suggestions were reported. As another application of the CNT transducer for lower peak negative pressure, EEG signals before and after sonication of shock waves for 10 minutes were observed in 3 rats. Shock wave by CNT transducer would be a potential for tcFUS neurostimulation and neuromodulation.


2020 ◽  
Vol 10 (14) ◽  
pp. 4778
Author(s):  
Hu Dong ◽  
Xiao Zou ◽  
Shengyou Qian

Through the introduction of multifrequency ultrasound technology, remarkable results have been achieved in tissue ablation and other aspects. By using the nonlinear dynamic equation of spherical bubble, the effects of the combination mode of multifrequency ultrasound, the peak negative pressure and its duration, the phase angle difference, and the polytropic index on the transient cavitation threshold in four different media of water, blood, brain, and liver are simulated and analyzed. The simulation results show that under the same frequency difference and initial bubble radius, the transient cavitation threshold of the high-frequency, triple-frequency combination is higher than that of the low-frequency, triple-frequency combination. When the lowest frequency of triple frequencies is the same, the larger the frequency difference, the higher the transient cavitation threshold. When the initial bubble radius is small, the frequency difference has little effect on the transient cavitation threshold of the triple-frequency combination. With the increase of initial bubble radius, the influence of frequency difference on the transient cavitation threshold of the higher frequency combination of triple frequency is more obvious than that of the lower frequency combination of triple frequency. When the duration of peak negative pressure or peak negative pressure of the multifrequency combined ultrasound is longer than that of the single-frequency ultrasound, the transient cavitation threshold of the multifrequency combined ultrasound is lower than that of the single-frequency ultrasound; on the contrary, the transient cavitation threshold of the multifrequency combined ultrasound is higher than that of the single-frequency ultrasound. When the phase angle difference of multifrequency excitation is zero, the corresponding transient cavitation threshold is the lowest, while the change of the polytropic index has almost no effect on the transient cavitation threshold for the multifrequency combination. The research results can provide a reference for multifrequency ultrasound to reduce the transient cavitation threshold, which is of great significance for the practical application of cavitation.


2021 ◽  
Author(s):  
Farah Hussein

Ultrasound and microbubble (USMB) enhances intracellular uptake through membrane disruption and endocytosis. This study investigates USMB effects on the molecular release incells through membrane-disruption and exocytosis. Retinal pigmented epithelial (RPE) cells were loaded with Alexa 647-transferrin (Tfn) to mark recycling endosomes, LAMP-1 antibody was used to mark lysosomes, GFP-transfected RPE cells were used to mark cytoplasm, and 7-AAD was used to assess cell viability. USMB exposure was done at 570kPa peak negative pressure for 1min. The mean fluorescent intensities (MFI) of markers were measured using flow cytometry. USMB induced the release of 19% and 67% of GFP from the cytoplasm in viable and non-viable cells respectively. LAMP-1 antibody MFI increased by 50% and 15-folds in viable and non-viable cells indicating USMB induced release from lysosomes. Furthermore, Tfn release from recycling endosomes increased by 22% only in viable cells. In conclusion, USMB enhances the molecular release from cytoplasm, lysosomes, and recycling endosomes


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