Ultrasound-enhanced systemic thrombolysis for acute ischemic stroke

BACKGROUND

Transcranial Doppler ultrasonography that is aimed at residual obstructive intracranial blood flow may help expose thrombi to tissue plasminogen activator (t-PA). Our objective was to determine whether ultrasonography can safely enhance the thrombolytic activity of t-PA.

METHODS

We treated all patients who had acute ischemic stroke due to occlusion of the middle cerebral artery with intravenous t-PA within three hours after the onset of symptoms. The patients were randomly assigned to receive continuous 2-MHz transcranial Doppler ultrasonography (the target group) or placebo (the control group). The primary combined end point was complete recanalization as assessed by transcranial Doppler ultrasonography or dramatic clinical recovery. Secondary end points included recovery at 24 hours, a favorable outcome at three months, and death at three months.

RESULTS

A total of 126 patients were randomly assigned to receive continuous ultrasonography (63 patients) or placebo (63 patients). Symptomatic intracerebral hemorrhage occurred in three patients in the target group and in three in the control group. Complete recanalization or dramatic clinical recovery within two hours after the administration of a t-PA bolus occurred in 31 patients in the target group (49 percent), as compared with 19 patients in the control group (30 percent; P=0.03). Twenty-four hours after treatment of the patients eligible for follow-up, 24 in the target group (44 percent) and 21 in the control group (40 percent) had dramatic clinical recovery (P=0.7). At three months, 22 of 53 patients in the target group who were eligible for follow-up analysis (42 percent) and 14 of 49 in the control group (29 percent) had favorable outcomes (as indicated by a score of 0 to 1 on the modified Rankin scale) (P=0.20).

CONCLUSIONS

In patients with acute ischemic stroke, continuous transcranial Doppler augments t-PA-induced arterial recanalization, with a nonsignificant trend toward an increased rate of recovery from stroke, as compared with placebo.

Acceleration of tibial fracture-healing by non-invasive, low-intensity pulsed ultrasound

Sixty-seven closed or grade-I open fractures of the tibial shaft were examined in a prospective, randomized, double-blind evaluation of use of a new ultrasound stimulating device as an adjunct to conventional treatment with a cast. Thirty-three fractures were treated with the active device and thirty-four, with a placebo control device. At the end of the treatment, there was a statistically significant decrease in the time to clinical healing (86 +/- 5.8 days in the active-treatment group compared with 114 +/- 10.4 days in the control group) (p = 0.01) and also a significant decrease in the time to over-all (clinical and radiographic) healing (96 +/- 4.9 days in the active-treatment group compared with 154 +/- 13.7 days in the control group) (p = 0.0001). The patients' compliance with the use of the device was excellent, and there were no serious complications related to its use. This study confirms earlier animal and clinical studies that demonstrated the efficacy of low-intensity ultrasound stimulation in the acceleration of the normal fracture-repair process.

Sonodynamic therapy--a review of the synergistic effects of drugs and ultrasound

Sonodynamic therapy, the ultrasound dependent enhancement of cytotoxic activities of certain compounds (sonosensitizers) in studies with cells in vitro and in tumor bearing animals, is reviewed. The attractive features of this modality for cancer treatment emerges from the ability to focus the ultrasound energy on malignancy sites buried deep in tissues and to locally activate a preloaded sonosensitizer. Possible mechanisms of sonodynamic therapy include generation of sonosensitizer derived radicals which initiate chain peroxidation of membrane lipids via peroxyl and/or alkoxyl radicals, the physical destabilization of the cell membrane by the sonosensitizer thereby rendering the cell more susceptible to shear forces or ultrasound enhanced drug transport across the cell membrane (sonoporation). Evidence against the role of singlet oxygen in sonodynamic therapy is discussed. The mechanism of sonodynamic therapy is probably not governed by a universal mechanism, but may be influenced by multiple factors including the nature of the biological model, the sonosensitizer and the ultrasound parameters. The current review emphasizes the effect of ultrasound induced free radicals in sonodynamic therapy.

Effect of nonsurgical periodontal therapy. I. Moderately advanced periodontitis

Healing events after nonsurgical periodontal therapy in patients with periodontal pockets 4--7 mm deep were investigated. Incisors, cuspids and premolars in 15 patients were treated by plaque control and supra- and subgingival debridement using hand or ultrasonic instruments in a split mouth approach. The results were evaluated by recordings of plaque scores, bleeding on probing, probing pocket depths and probing attachment levels. All these parameters were improved during the initial 4--5 months after start of therapy. Little change occurred during the rest of the 13-month observation period. No difference of results could be observed comparing hand and ultrasonic instrumentation or comparing the results of two different operators. Initially a total of 106 sites demonstrated probing pocket depths greater than or equal to 6 mm. At 13 months only 13 such sites were observed. The apparently successful results of conservative treatment of patients with 4--7 mm deep pockets in the present study raise the question to what extent nonsurgical therapy is feasible also in patients with severely advanced lesions.

Shock wave therapy induces neovascularization at the tendon-bone junction. A study in rabbits

Despite the success in clinical application, the exact mechanism of shock wave therapy remains unknown. We hypothesized that shock wave therapy induces the ingrowth of neovascularization and improves blood supply to the tissues. The purpose of this study was to investigate the effect of shock wave therapy on neovascularization at the tendon-bone junction. Fifty New Zealand white rabbits with body weight ranging from 2.5 to 3.5 kg were used in this study. The right limb (the study side) received shock wave therapy to the Achilles tendon near the insertion to bone. The left limb (the control side) received no shock wave therapy. Biopsies of the tendon-bone junction were performed in 0, 1, 4, 8 and 12 weeks. The number of neo-vessels was examined microscopically with hematoxylin-eosin stain. Neovascularization was confirmed by the angiogenic markers including vessel endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) expressions and endothelial cell proliferation determined by proliferating cell nuclear antigen (PCNA) expression examined microscopically with immunohistochemical stains. The results showed that shock wave therapy produced a significantly higher number of neo-vessels and angiogenesis-related markers including eNOS, VEGF and PCNA than the control without shock wave treatment. The eNOS and VEGF began to rise in as early as one week and remained high for 8 weeks, then declined at 12 weeks; whereas the increases of PCNA and neo-vessels began at 4 weeks and persisted for 12 weeks. In conclusion, shock wave therapy induces the ingrowth of neovascularization associated with early release of angiogenesis-related markers at the Achilles tendon-bone junction in rabbits. The neovascularization may play a role to improve blood supply and tissue regeneration at the tendon-bone junction.

Corticosteroid injections, physiotherapy, or a wait-and-see policy for lateral epicondylitis: a randomised controlled trial

BACKGROUND

Lateral epicondylitis is generally treated with corticosteroid injections or physiotherapy. Dutch clinical guidelines recommend a wait-and-see policy. We compared the efficacy of these approaches.

METHODS

Patients with lateral epicondylitis of at least 6 weeks' duration were recruited by family doctors. We randomly allocated eligible patients to 6 weeks of treatment with corticosteroid injections, physiotherapy, or a wait-and-see policy. Outcome measures included general improvement, severity of the main complaint, pain, elbow disability, and patient satisfaction. Severity of elbow complaints, grip strength, and pressure pain threshold were assessed by a research physiotherapist who was unaware of treatment allocation. We assessed all outcomes at 3, 6, 12, 26, and 52 weeks. The principal analysis was done on an intention-to-treat basis.

FINDINGS

We randomly assigned 185 patients. At 6 weeks, corticosteroid injections were significantly better than all other therapy options for all outcome measures. Success rates were 92% (57) compared with 47% (30) for physiotherapy and 32% (19) for wait-and-see policy. However, recurrence rate in the injection group was high. Long-term differences between injections and physiotherapy were significantly in favour of physiotherapy. Success rates at 52 weeks were 69% (43) for injections, 91% (58) for physiotherapy, and 83% (49) for a wait-and-see policy. Physiotherapy had better results than a wait-and-see policy, but differences were not significant.

INTERPRETATION

Patients should be properly informed about the advantages and disadvantages of the treatment options for lateral epicondylitis. The decision to treat with physiotherapy or to adopt a wait-and-see policy might depend on available resources, since the relative gain of physiotherapy is small.

Nanoenzyme-Augmented Cancer Sonodynamic Therapy by Catalytic Tumor Oxygenation

Ultrasound (US)-triggered sonodynamic therapy (SDT) can solve the critical issue of low tissue-penetrating depth of traditional phototriggered therapies, but the SDT efficacy is still not satisfactorily high in combating cancer at the current stage. Here we report on augmenting the SDT efficacy based on catalytic nanomedicine, which takes the efficient catalytic features of nanoenzymes to modulate the tumor microenvironment (TME). The multifunctional nanosonosensitizers have been successfully constructed by the integration of a MnO _x component with biocompatible/biodegradable hollow mesoporous organosilica nanoparticles, followed by conjugation with protoporphyrin (as the sonosensitizer) and cyclic arginine-glycine-aspartic pentapeptide (as the targeting peptide). The MnO _x component in the composite nanosonosensitizer acts as an inorganic nanoenzyme for converting the tumor-overexpressed hydrogen peroxide (H₂O₂) molecules into oxygen and enhancing the tumor oxygen level subsequently, which has been demonstrated to facilitate SDT-induced reactive oxygen species production and enhance SDT efficacy subsequently. The targeted accumulation of these composite nanosonosensitizers efficiently suppressed the growth of U87 tumor xenograft on nude mice after US-triggered SDT treatment. The high in vivo biocompatibility and easy excretion of these multifunctional nanosonosensitizers from the body have also been evaluated and demonstrated to guarantee their future clinical translation, and their TME-responsive T₁-weighted magnetic resonance imaging capability provides the potential for therapeutic guidance and monitoring during SDT.

Experimental demonstration of noninvasive transskull adaptive focusing based on prior computed tomography scans

Developing minimally invasive brain surgery by high-intensity focused ultrasound beams is of great interest in cancer therapy. However, the skull induces strong aberrations both in phase and amplitude, resulting in a severe degradation of the beam shape. Thus, an efficient brain tumor therapy would require an adaptive focusing, taking into account the effects of the skull. In this paper, we will show that the acoustic properties of the skull can be deduced from high resolution CT scans and used to achieve a noninvasive adaptive focusing. Simulations have been performed with a full 3-D finite differences code, taking into account all the heterogeneities inside the skull. The set of signals to be emitted in order to focus through the skull can thus be computed. The complete adaptive focusing procedure based on prior CT scans has been experimentally validated. This could have promising applications in brain tumor hyperthermia but also in transcranial ultrasonic imaging.

Ultrasound mediated delivery of drugs and genes to solid tumors

It has long been shown that therapeutic ultrasound can be used effectively to ablate solid tumors, and a variety of cancers are presently being treated in the clinic using these types of ultrasound exposures. There is, however, an ever-increasing body of preclinical literature that demonstrates how ultrasound energy can also be used non-destructively for increasing the efficacy of drugs and genes for improving cancer treatment. In this review, a summary of the most important ultrasound mechanisms will be given with a detailed description of how each one can be employed for a variety of applications. This includes the manner by which acoustic energy deposition can be used to create changes in tissue permeability for enhancing the delivery of conventional agents, as well as for deploying and activating drugs and genes via specially tailored vehicles and formulations.

Hyperthermia in oncology

The purpose of this article is to provide an overview on the current clinical application of hyperthermia combined with conventional treatment modalities (e.g. ionizing radiation, chemotherapy) in the treatment of malignant disease. The clinical application of hyperthermia with increase of tissue temperatures (range 40-44 degrees C) has been integrated in multimodal anti-cancer strategies. This review describes selected phase I or II (n = 17) and phase III trials (n = 16) investigating the effect of hyperthermia combined with radiotherapy (n = 10 trials), chemotherapy (n = 15 trials), or both (n = 8 trials) in a total of more than 2200 patients. The trials were performed in a variety of solid tumours (e.g. melanoma, head and neck cancer, breast cancer, cancer of the gastrointestinal or urogenital tract, glioblastoma, sarcoma) in paediatric or adult patients. Profound research has produced a scientific basis for the simultaneous application of hyperthermia in combination with ionizing radiation and/or systemic chemotherapy. Hyperthermia is becoming more accepted clinically, due to the substantial technical improvements made in achieving selected increase of temperatures in superficial and deep-seated tumours. At present, the combination of hyperthermia and chemotherapy or radiochemotherapy is further tested within clinical protocols (phase II/III) in order to improve local tumour control and relapse-free survival in patients with high-risk or advanced tumours of different entities.

Recent Advances in Nanomaterial-Assisted Combinational Sonodynamic Cancer Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT), as a promising noninvasive therapeutic modality, has received ever-increasing attention in recent years. Its specialized chemical agents, named sonosensitizers, are activated by low-intensity US to produce lethal reactive oxygen species (ROS) for oncotherapy. Compared with phototherapeutic strategies, SDT provides many noteworthy opportunities and benefits, such as deeper penetration depth, absence of phototoxicity, and fewer side effects. Nevertheless, previous studies have also demonstrated its intrinsic limitations. Thanks to the facile engineering nature of nanotechnology, numerous novel nanoplatforms are being applied in this emerging field to tackle these intrinsic barriers and achieve continuous innovations. In particular, the combination of SDT with other treatment strategies has demonstrated a superior efficacy in improving anticancer activity relative to that of monotherapies alone. Therefore, it is necessary to summarize the nanomaterial-assisted combinational sonodynamic cancer therapy applications. Herein, the design principles in achieving synergistic therapeutic effects based on nanomaterial engineering methods are highlighted. The ultimate goals are to stimulate the design of better-quality combined sonodynamic treatment schemes and provide innovative ideas for the perspectives of SDT in promoting its future transformation to clinical application.

Treatment of periodontal disease in diabetics reduces glycated hemoglobin

Periodontal disease is a common infection-induced inflammatory disease among individuals suffering from diabetes mellitus. The purpose of this study was to assess the effects of treatment of periodontal disease on the level of metabolic control of diabetes. A total of 113 Native Americans (81 females and 32 males) suffering from periodontal disease and non-insulin dependent diabetes mellitus (NIDDM) were randomized into 5 treatment groups. Periodontal treatment included ultrasonic scaling and curettage combined with one of the following antimicrobial regimens: 1) topical water and systemic doxycycline, 100 mg for 2 weeks; 2) topical 0.12% chlorhexidine (CHX) and systemic doxycycline, 100 mg for 2 weeks; 3) topical povidone-iodine and systemic doxycycline, 100 mg for 2 weeks; 4) topical 0.12% CHX and placebo; and 5) topical water and placebo (control group). Assessments were performed prior to and at 3 and 6 months after treatment and included probing depth (PD), clinical attachment level (CAL), detection of Porphyromonas gingivalis in subgingival plaque and determination of serum glucose and glycated hemoglobin (HbA1c). After treatment all study groups showed clinical and microbial improvement. The doxycycline-treated groups showed the greatest reduction in probing depth and subgingival Porphyromonas gingivalis compared to the control group. In addition, all 3 groups receiving systemic doxycycline showed, at 3 months, significant reductions (P < or = 0.04) in mean HbA1c reaching nearly 10% from the pretreatment value. Effective treatment of periodontal infection and reduction of periodontal inflammation is associated with a reduction in level of glycated hemoglobin. Control of periodontal infections should thus be an important part of the overall management of diabetes mellitus patients.

Treatment of tendinopathy: what works, what does not, and what is on the horizon

Tendinopathy is a broad term encompassing painful conditions occurring in and around tendons in response to overuse. Recent basic science research suggests little or no inflammation is present in these conditions. Thus, traditional treatment modalities aimed at controlling inflammation such as corticosteroid injections and nonsteroidal antiinflammatory medications (NSAIDS) may not be the most effective options. We performed a systematic review of the literature to determine the best treatment options for tendinopathy. We evaluated the effectiveness of NSAIDS, corticosteroid injections, exercise-based physical therapy, physical therapy modalities, shock wave therapy, sclerotherapy, nitric oxide patches, surgery, growth factors, and stem cell treatment. NSAIDS and corticosteroids appear to provide pain relief in the short term, but their effectiveness in the long term has not been demonstrated. We identified inconsistent results with shock wave therapy and physical therapy modalities such as ultrasound, iontophoresis and low-level laser therapy. Current data support the use of eccentric strengthening protocols, sclerotherapy, and nitric oxide patches, but larger, multicenter trials are needed to confirm the early results with these treatments. Preliminary work with growth factors and stem cells is promising, but further study is required in these fields. Surgery remains the last option due to the morbidity and inconsistent outcomes. The ideal treatment for tendinopathy remains unclear.

LEVEL OF EVIDENCE

Level II, systematic review.

Metal-Organic-Framework-Derived Carbon Nanostructure Augmented Sonodynamic Cancer Therapy

Sonodynamic therapy (SDT) can overcome the critical issue of depth-penetration barrier of photo-triggered therapeutic modalities. However, the discovery of sonosensitizers with high sonosensitization efficacy and good stability is still a significant challenge. In this study, the great potential of a metal-organic-framework (MOF)-derived carbon nanostructure that contains porphyrin-like metal centers (PMCS) to act as an excellent sonosensitizer is identified. Excitingly, the superior sonosensitization effect of PMCS is believed to be closely linked to the porphyrin-like macrocycle in MOF-derived nanostructure in comparison to amorphous carbon nanospheres, due to their large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for high reactive oxygen species (ROS) production. The nanoparticle-assisted cavitation process, including the visualized formation of the cavitation bubbles and microjets, is also first captured by high-speed camera. High ROS production in PMCS under ultrasound is validated by electron spin resonance and dye measurement, followed by cellular destruction and high tumor inhibition efficiency (85%). This knowledge is important from the perspective of understanding the structure-dependent SDT enhancement of a MOF-derived carbon nanostructure.

Ultrasound-mediated blood-brain barrier disruption for targeted drug delivery in the central nervous system

The physiology of the vasculature in the central nervous system (CNS), which includes the blood-brain barrier (BBB) and other factors, complicates the delivery of most drugs to the brain. Different methods have been used to bypass the BBB, but they have limitations such as being invasive, non-targeted or requiring the formulation of new drugs. Focused ultrasound (FUS), when combined with circulating microbubbles, is a noninvasive method to locally and transiently disrupt the BBB at discrete targets. This review provides insight on the current status of this unique drug delivery technique, experience in preclinical models, and potential for clinical translation. If translated to humans, this method would offer a flexible means to target therapeutics to desired points or volumes in the brain, and enable the whole arsenal of drugs in the CNS that are currently prevented by the BBB.

Physical therapy for patellofemoral pain: a randomized, double-blinded, placebo-controlled trial

BACKGROUND

Although physical therapy forms the mainstay of nonoperative management for patellofemoral pain, its efficacy has not been established.

HYPOTHESIS

Significantly more pain relief will be achieved from a 6-week regimen of physical therapy than from placebo treatment.

STUDY DESIGN

Multicenter, randomized, double-blinded, placebo-controlled trial.

METHODS

Seventy-one subjects, 40 years of age or younger with patellofemoral pain of 1 month or longer, were randomly allocated to a physical therapy or placebo group. A standardized treatment program consisted of six treatment sessions, once weekly. Physical therapy included quadriceps muscle retraining, patellofemoral joint mobilization, and patellar taping, and daily home exercises. The placebo treatment consisted of sham ultrasound, light application of a nontherapeutic gel, and placebo taping.

RESULTS

Sixty-seven participants completed the trial. The physical therapy group (N = 33) demonstrated significantly greater reduction in the scores for average pain, worst pain, and disability than did the placebo group (N = 34).

CONCLUSIONS

A six-treatment, 6-week physical therapy regimen is efficacious for alleviation of patellofemoral pain.

MRI Guidance of Focused Ultrasound Therapy of Uterine Fibroids:Early Results

OBJECTIVE

The purpose of this study was to explore our hypothesis that MRI-guided focused ultrasound therapy for the treatment of uterine fibroids will lead to a significant reduction in symptoms and improvement in quality of life. We describe focused ultrasound therapy applications and the method for monitoring the thermal energy deposited in the fibroids, including the MRI parameters required, in a prospective review of 108 treatments.

MATERIALS AND METHODS

Patients presenting with symptomatic uterine fibroids who attained a minimal symptom severity score and who would otherwise have been offered a hysterectomy were recruited. Thermal lesions were created within target fibroids using an MRI-guided focused ultrasound therapy system. The developing lesion was monitored using real-time MR thermometry, which was used to assess treatment outcome in real time to change treatment parameters and achieve the desired outcome. Fibroid volume, fibroid symptoms, and quality-of-life scores were measured before treatment and 6 months after treatment. Adverse events were actively monitored and recorded.

RESULTS

In this study, 79.3% of women who had been treated reported a significant improvement in their uterine fibroid symptoms on follow-up health-related quality-of-life questionnaires, which supports our hypothesis. The mean reduction in fibroid volume at 6 months was 13.5%, but nonenhancing volume (mean, 51 cm(3)) remained within the treated fibroid at 6 months.

CONCLUSION

This early description of MRI-guided focused ultrasound therapy treatment of fibroids includes follow-up data and shows that, although the volume reduction is moderate, it correlates with treatment volume and the symptomatic response to this treatment is encouraging.

Intelligent Hollow Pt-CuS Janus Architecture for Synergistic Catalysis-Enhanced Sonodynamic and Photothermal Cancer Therapy

As a noninvasive treatment modality, ultrasound (US)-triggered sonodynamic therapy (SDT) shows broad and promising applications to overcome the drawbacks of traditional photodynamic therapy (PDT) in combating cancer. However, the SDT efficacy is still not satisfactory without oxygen (O₂) assistance. In addition, there is also much space to explore the SDT-based synergistic therapeutic modalities. Herein, a novel Pt-CuS Janus composed of hollow semiconductor CuS and noble metallic Pt was rationally designed and successfully synthesized. The hollow CuS shows a large inner cavity for loading sonosensitizer molecules (tetra-(4-aminophenyl) porphyrin, TAPP) to implement SDT. Moreover, the deposition of Pt not only enhances photothermal performance compared with those of CuS nanoparticles (NPs) due to the effect of the local electric field enhancement but also possesses nanozyme activity for catalyzing decomposition of endogenous overexpressed hydrogen peroxide (H₂O₂) to produce O₂ that can overcome tumor hypoxia and augment the SDT-induced highly toxic reactive oxygen species (ROS) production for efficient cancer cell apoptosis. Importantly, the generated heat of Pt-CuS by 808 nm laser irradiation can accelerate the catalytic activity of Pt and elevate the O₂ level that further facilitates SDT efficacy. Interestingly, the thermally sensitive copolymer coated around the Janus can act as a smart switch to regulate the catalytic ability of Pt and control TAPP release that has a significant effect on modulating the therapeutic effect. The synergistic catalysis-enhanced SDT efficiency and highly photothermal effect almost realized complete tumor resection without obvious reoccurrence and simultaneously displayed a highly therapeutic biosafety. Furthermore, the high optical absorbance allows the as-synthesized Pt-CuS Janus for photoacoustic (PA) imaging and NIR thermal imaging. This work develops a versatile nanoplatform for a multifunctional theranostic strategy and broadens the biological applications by rationally designing their structure.

Hematoporphyrin as a sensitizer of cell-damaging effect of ultrasound

Mouse sarcoma 180 or rat ascites hepatoma (AH) 130 cells were exposed to ultrasound (US; 1.27, 2.21 and 3.18 W/cm2; 1.92 MHz) for up to 60 s in vitro in the presence or absence of hematoporphyrin (Hp; 10, 25 and 50 micrograms/ml). The cell-damaging effects of treatments were determined by means of the Trypan Blue dye exclusion test. Hp alone did not show any cell-damaging effect, whereas US alone damaged 30 and 50% of sarcoma and AH 130 cells, respectively, at the maximum intensity for 60 s. In the presence of 50 micrograms/ml Hp, US damaged 99 and 95% of the above tumor cells, respectively. These results show that Hp increased the sensitivity of tumor cells to US.

Low-intensity pulsed ultrasound accelerates rat femoral fracture healing by acting on the various cellular reactions in the fracture callus

Low-intensity pulsed ultrasound (LIPUS) has been shown to accelerate fracture healing in both animal models and clinical trials, but the mechanism of action remains unclear. In fracture healing, various consecutive cellular reactions occurred until repair. We investigated whether the advanced effects of LIPUS depended on the duration and timing of LIPUS treatment in a rat closed femoral fracture model to determine the target of LIPUS in the healing process. Sixty-nine Long-Evans male rats that have bilateral closed femoral fractures were used. The right femur was exposed to LIPUS (30 mW/cm2 spatial and temporal average [SATA], for 20 minutes/day), and the left femur was used as a control. Rats were divided into four groups according to timing and duration of treatment (Ph-1, days 1-8; Ph-2, days 9-16; Ph-3, days 17-24; throughout [T], days 1-24 after the fracture). Animals were killed on day 25. After radiographs and microfocus X-ray computed tomography (muCT) tomograms were taken, the hard callus area (HCA), bone mineral content (BMC) at the fracture site, and mechanical torsion properties were measured, and histological analysis was conducted. Interestingly, the maximum torque of the LIPUS-treated femur was significantly greater than that of the controls in all groups without any changes in HCA and BMC. The multiviewing of three-dimensional (3D) muCT reconstructions and histology supported our findings that the partial LIPUS treatment time was able to accelerate healing, but longer treatment was more effective. These results suggest that LIPUS acts on some cellular reactions involved in each phase of the healing process such as inflammatory reaction, angiogenesis, chondrogenesis, intramembranous ossification, endochondral ossification, and bone remodeling.

Ultrasound accelerates transport of recombinant tissue plasminogen activator into clots

Fibrinolysis is accelerated in vitro in an ultrasound field, and externally applied high frequency ultrasound also accelerates thrombolysis in animal models. Although the mechanism of this effect is not known, ultrasound does not cause mechanical disruption of clots but rather accelerates enzymatic fibrinolysis. To determine if accelerated fibrinolysis could be related to increased transport of enzyme into clot, we have examined the effect of insonification on the distribution of plasminogen activator between clot and surrounding fluid in vitro. Plasma clots were overlayed with plasma containing 125I-radiolabeled, active-site-blocked recombinant tissue plasminogen activator (rt-PA) and incubated in the presence of 1-MHz ultrasound at 4 W/cm2 or in the absence of ultrasound. The rate of uptake of rt-PA was significantly faster in the presence of ultrasound, reaching 15.5 +/- 1.4% at 4 h compared to 8.2 +/- 1.0% in the absence of ultrasound (p < 0.0001). Similarly, ultrasound increased transport of enzyme from the clot into the surrounding fluid. To determine the effect of ultrasound on the spatial distribution of enzyme, plasma clots were overlayed with plasma containing radiolabeled rt-PA and incubated in the presence or absence of ultrasound. The clots were then snap-frozen, and the radioactivity in serial cryotome sections was determined. Exposure to ultrasound altered the rt-PA distribution, resulting in significantly deeper penetration of rt-PA into the clots. We conclude that exposure to ultrasound increases uptake of rt-PA into clots and also results in deeper penetration. These effects of ultrasound on enzyme transport may contribute to the accelerated fibrinolysis observed in an ultrasound field.

Ultrasound-Switchable Nanozyme Augments Sonodynamic Therapy against Multidrug-Resistant Bacterial Infection

Ultrasound (US)-driven sonodynamic therapy (SDT) has demonstrated wide application prospects in the eradication of deep-seated bacterial infections due to its noninvasiveness, site-confined irradiation, and high-tissue-penetrating capability. However, the ineffective accumulation of sonosensitizers at the infection site, the hypoxic microenvironment, as well as rapid depletion of oxygen during SDT greatly hamper the therapeutic efficacy of SDT. Herein, an US-switchable nanozyme system was proposed for the controllable generation of catalytic oxygen and sonosensitizer-mediated reactive oxygen species during ultrasound activation, thereby alleviating the hypoxia-associated barrier and augmenting SDT efficacy. This nanoplatform (Pd@Pt-T790) was easily prepared by bridging enzyme-catalytic Pd@Pt nanoplates with the organic sonosensitizer meso-tetra(4-carboxyphenyl)porphine (T790). It was really interesting to find that the modification of T790 onto Pd@Pt could significantly block the catalase-like activity of Pd@Pt, whereas upon US irradiation, the nanozyme activity was effectively recovered to catalyze the decomposition of endogenous H₂O₂ into O₂. Such "blocking and activating" enzyme activity was particularly important for decreasing the potential toxicity and side effects of nanozymes on normal tissues and has potential to realize active, controllable, and disease-loci-specific nanozyme catalytic behavior. Taking advantage of this US-switchable enzyme activity, outstanding accumulation in infection sites, as well as excellent biocompatibility, the Pd@Pt-T790-based SDT nanosystem was successfully applied to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced myositis, and the sonodynamic therapeutic progression was noninvasively monitored by photoacoustic imaging and magnetic resonance imaging. The developed US-switchable nanoenzyme system provides a promising strategy for augmenting sonodynamic eradication of deep-seated bacterial infection actively, controllably, and precisely.

Doxorubicin as a molecular nanotheranostic agent: effect of doxorubicin encapsulation in micelles or nanoemulsions on the ultrasound-mediated intracellular delivery and nuclear trafficking

Doxorubicin (DOX) is one of the most commonly used chemotherapeutic drugs and is a popular research tool due to the inherent fluorescence of the DOX molecule. After DOX injection, fluorescence imaging of organs or cells can provide information on drug biodistribution. Therapeutic and imaging capabilities combined in a DOX molecule make it an excellent theranostic agent. However, DOX fluorescence depends on a number of factors that should be taken into consideration when interpreting results of DOX fluorescence measurements. Discussing these problems is the main thrust of the current paper. The sensitivity of DOX fluorescence intensity to DOX concentration, local microenvironment, and interaction with model cellular components is illustrated by fluorescence spectra of paired DOX/phospholipid, DOX/histone, DOX/DNA, and triple DOX/histone/DNA and DOX/phospholipid/DNA systems. DOX fluorescence is dramatically quenched upon intercalation into the DNA; DOX fluorescence is also self-quenched at high concentrations of molecularly dissolved DOX; in contrast, DOX fluorescence is increased after binding to the histone or partitioning into the phospholipid phase of PEG-phospholipid micelles or hydrophobic cores of polymeric micelles. While flow cytometry is commonly used for characterization of DOX intracellular uptake, the above aspects of DOX fluorescence may significantly complicate interpretation of flow cytometry results. High cell fluorescence measured by flow cytometry may provide deceptive information on the actual intracellular DOX concentration and may not correlate with the therapeutic efficacy if DOX does not penetrate into the site of action in cell nuclei. These problems are illustrated in the experiments on the intracellular trafficking of DOX encapsulated in poly(ethylene glycol)-co-polycaprolactone (PEG-PCL) micelles or PEG-PCL stabilized perfluorocarbon nanodroplets, with and without the application of ultrasound used as an external trigger. For efficient encapsulation in micelle cores, DOX is usually deprotonated, which removes the positive charge and enhances hydrophobicity of DOX molecule. It was found that the deprotonated DOX accumulated in the cell cytoplasm but did not penetrate into the cell nuclei. The same was true for the DOX encapsulated in micelles or nanodroplets, which may explain their low therapeutic efficacy in the absence of ultrasound. Ultrasound triggers DOX trafficking into the cell nuclei, which is especially pronounced in the presence of nanoemulsions that convert into microbubbles under the ultrasound action. Microbubble cavitation results in the transient permeabilization of both plasma and nuclear membranes, thus allowing DOX penetration into the cell nuclei, which dramatically enhances therapeutic efficacy of DOX-loaded nanodroplet systems.

A novel site-targeted ultrasonic contrast agent with broad biomedical application

BACKGROUND

In this work, we report a novel targetable ultrasonic contrast agent with the potential to noninvasively define and localize myriad pathological tissues for diagnosis or therapy. The agent is a biotinylated, lipid-coated, perfluorocarbon emulsion that has low inherent echogenicity unless bound to a surface or itself.

METHODS AND RESULTS

In study 1, emulsions with and without biotin were suspended in buffered saline and imaged with a 7.5-MHz linear-array transducer. Neither emulsion manifested significant ultrasonic backscatter until avidin was added. Avidin-induced aggregation produced a marked enhancement in backscatter from the biotinylated but not from the control emulsion. In study 2, porcine fibrin clots in vitro were pretargeted with biotinylated antifibrin monoclonal antibodies and then exposed to avidin and then to biotinylated or control perfluorocarbon emulsions. The basal acoustic reflectivity of clots imaged with a 7.5-MHz linear-array transducer was uniformly low and was increased substantially by exposure to the targeted biotinylated emulsion. In study 3, partially occlusive arterial thrombi were created in dogs and then exposed to antifibrin antibodies and avidin in situ. Biotinylated or control emulsion was administered either in situ or systemically. At baseline, all thrombi were undetectable with a 7.5-MHz linear-array transducer. Thrombi exposed to antifibrin-targeted contrast exhibited increased echogenicity (P < .05); control thrombi remained acoustically undetectable.

CONCLUSIONS

These data provide the first in vivo demonstration of a site-specific ultrasonic contrast agent and have potential for improved sensitivity and specificity for noninvasive diagnosis of thrombi and other pathological diseases.