The effect of fish bodies on the source level and beam pattern of acoustic transmitters in juvenile Chinook salmon.

The effect of the fish body on the source level and beam pattern of an acoustic fish tag signal was investigated through laboratory experiments and an analytical method. In laboratory experiments, the source level and beam pattern were measured in both a tag-only group and a tag-in-fish group. In the analytical method, both forward and backward scattering were calculated by assuming the acoustic tag was a point source and the swimbladder was an air-filled prolate spheroid. The mean source level of five tested tags decreased by ∼4 dB after implantation in fish bodies, which is important for designing fish migration studies using acoustic telemetry.

Microporous and Flexible Framework Acoustic Metamaterials for Sound Attenuation and Contrast Agent Applications.

The low-frequency (100-1250 Hz) acoustic properties of metal-organic framework (MOF) materials were examined in impedance tube experiments. The anomalously high sound transmission loss of HKUST-1, FeBTC, and MIL-53(Al) quantitatively demonstrated that these prototypical MOFs are absorptive acoustic metamaterials. To the best of our knowledge, this is the first example of MOFs that have been demonstrated to be acoustic metamaterials. Low-frequency acoustic dampening by subwavelength MOF metamaterials is likely due to sound dissipation and absorption facilitated by multiple internal reflections within the microporous framework structure. Modification of MIL-53(Al) with flexible organic linkers clarified that acoustic signatures of the MOFs may be tailored to add or alter certain diagnostic acoustic signatures. These results may be applied to the rational design of lightweight sound-insulating construction materials and acoustic contrast agents for subsurface mapping and monitoring applications at low frequency (100-1250 Hz).

Chemotherapeutic drug-specific alteration of microvascular blood flow in murine breast cancer as measured by diffuse correlation spectroscopy.

The non-invasive, in vivo measurement of microvascular blood flow has the potential to enhance breast cancer therapy monitoring. Here, longitudinal blood flow of 4T1 murine breast cancer (N=125) under chemotherapy was quantified with diffuse correlation spectroscopy based on layer models. Six different treatment regimens involving doxorubicin, cyclophosphamide, and paclitaxel at clinically relevant doses were investigated. Treatments with cyclophosphamide increased blood flow as early as 3 days after administration, whereas paclitaxel induced a transient blood flow decrease at 1 day after administration. Early blood flow changes correlated strongly with the treatment outcome and distinguished treated from untreated mice individually for effective treatments.

Non-Invasive Monitoring of Temporal and Spatial Blood Flow during Bone Graft Healing Using Diffuse Correlation Spectroscopy.

Vascular infiltration and associated alterations in microvascular blood flow are critical for complete bone graft healing. Therefore, real-time, longitudinal measurement of blood flow has the potential to successfully predict graft healing outcomes. Herein, we non-invasively measure longitudinal blood flow changes in bone autografts and allografts using diffuse correlation spectroscopy in a murine femoral segmental defect model. Blood flow was measured at several positions proximal and distal to the graft site before implantation and every week post-implantation for a total of 9 weeks (autograft n = 7 and allograft n = 10). Measurements of the ipsilateral leg with the graft were compared with those of the intact contralateral control leg. Both autografts and allografts exhibited an initial increase in blood flow followed by a gradual return to baseline levels. Blood flow elevation lasted up to 2 weeks in autografts, but this duration varied from 2 to 6 weeks in allografts depending on the spatial location of the measurement. Intact contralateral control leg blood flow remained at baseline levels throughout the 9 weeks in the autograft group; however, in the allograft group, blood flow followed a similar trend to the graft leg. Blood flow difference between the graft and contralateral legs (ΔrBF), a parameter defined to estimate graft-specific changes, was elevated at 1-2 weeks for the autograft group, and at 2-4 weeks for the allograft group at the proximal and the central locations. However, distal to the graft, the allograft group exhibited significantly greater ΔrBF than the autograft group at 3 weeks post-surgery (p < 0.05). These spatial and temporal differences in blood flow supports established trends of delayed healing in allografts versus autografts.

Optically measured microvascular blood flow contrast of malignant breast tumors.

Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS), a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval) tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63); tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66), and using normal tissue in the contralateral breast was 2.27 (1.90-2.70). Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.

Effects of SKI306X on arachidonate metabolism and other inflammatory mediators.

SKI306X was previously reported to have good anti-inflammatory and analgesic efficacy in various studies. To determine its mode of action, an investigation was carried out for some representative mediators. Arachidonic acid metabolism and its products are particularly important in inflammation and pain. The pro-inflammatory cytokines, especially interleukin-1 (IL-1) and tumor necrosis factor (TNF-alpha), and induced nitric oxide (NO) appear to be most involved in the inflammatory process such as osteoarthritis (OA). Thus SKI306X was tested to determine the effects on enzymes related to arachidonic acid metabolism and the release or synthesis of inflammatory mediators. SKI306X did inhibit the expression of cyclooxygenase-2 (COX-2) enzyme without affecting COX-1 and COX-2 activity. Leukotriene B4 (LTB4) production also was inhibited by SKI306X (IC50 = 98.7+/-4.26 microg/ml). SKI306X inhibited significantly TNF-alpha release (IC50 = 97.6+/-17.8 microg/ml) and NO production (IC50 = 280+/-17.8 microg/ml). But IL-1alpha release was not attenuated by SKI306X. This study suggests that inhibition of these mediators by SKI306X may be one of the mechanisms responsible for its anti-inflammatory effects.

SKI306X suppresses cartilage destruction and inhibits the production of matrix metalloproteinase in rabbit joint cartilage explant culture.

SKI306X was previously found to have cartilage protective effects in the experimental osteoarthritis (OA) model. To investigate the chondro-protective benefits of SKI306X for its capacity in altering changes in cartilage metabolism and molecular mechanisms of cartilage protective action, SKI306X is studied in rabbit cartilage explants culture. To investigate the protective effect of SKI306X on cartilage catabolism, we assessed collagen degradation in rabbit cartilage explants treated with interleukin-1alpha up to 3 weeks. To examine the reaction mechanism, matrix metalloproteinase (MMPs) were investigated by fluorimetric and Western blotting analysis. In addition, its effects on the activation process of proenzyme MMP-3 were determined by gelatin zymography. SKI306X significantly inhibited collagen degradation and inhibited the activities of several MMPs. Total MMPs activities in cultured medium were substantially increased in the third week at the time of collagen degradation with the absence of SKI306. However, the introduction of SKI306X decreased MMPs activities in cultured medium. Furthermore, Western blotting analysis proved that these inhibitory effects of this drug were the result of inhibiting MMPs expression. SKI306X also inhibited the activation of proenzyme MMP-3 to the active form of MMP-3. These results indicate that SKI306X inhibits matrix degradation by down regulating MMPs expression and secretion, inhibition of MMPs activity, and inhibiting activation of MMP-3 during the collagen breakdown process.