The role of ultrasound-driven microbubble dynamics in drug delivery : from microbubble fundamentals to clinical translation

In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size and physicochemistry of the bubble shell) that play a key role in microbubble cell interactions and in the associated therapeutic outcome. Additionally, new techniques that may provide additional control over the treatment, such as monodisperse microbubble formulations, tunable ultrasound scanners, and cavitation detection techniques, are discussed. An in-depth understanding of the aspects presented in this work could eventually lead the way to more efficient and tailored microbubble-assisted ultrasound therapy in the future

Accuracy of transcranial magnetic stimulation and a Bayesian latent class model for diagnosis of spinal cord dysfunction in horses

Background: Spinal cord dysfunction/compression and ataxia are common in horses. Presumptive diagnosis is most commonly based on neurological examination and cervical radiography, but the interest into the diagnostic value of transcranial magnetic stimulation (TMS) with recording of magnetic motor evoked potentials has increased. The problem for the evaluation of diagnostic tests for spinal cord dysfunction is the absence of a gold standard in the living animal. Objectives: To compare diagnostic accuracy of TMS, cervical radiography, and neurological examination. Animals: One hundred seventy-four horses admitted at the clinic for neurological examination. Methods: Retrospective comparison of neurological examination, cervical radiography, and different TMS criteria, using Bayesian latent class modeling to account for the absence of a gold standard. Results: The Bayesian estimate of the prevalence (95% CI) of spinal cord dysfunction was 58.1 (48.3%-68.3%). Sensitivity and specificity of neurological examination were 97.6 (91.4%-99.9%) and 74.7 (61.0%-96.3%), for radiography they were 43.0 (32.3%-54.6%) and 77.3 (67.1%-86.1%), respectively. Transcranial magnetic stimulation reached a sensitivity and specificity of 87.5 (68.2%-99.2%) and 97.4 (90.4%-99.9%). For TMS, the highest accuracy was obtained using the minimum latency time for the pelvic limbs (Youden's index = 0.85). In all evaluated models, cervical radiography performed poorest. Clinical Relevance: Transcranial magnetic stimulation-magnetic motor evoked potential (TMS-MMEP) was the best test to diagnose spinal cord disease, the neurological examination was the second best, but the accuracy of cervical radiography was low. Selecting animals based on neurological examination (highest sensitivity) and confirming disease by TMS-MMEP (highest specificity) would currently be the optimal diagnostic strategy

Magnetic motor evoked potentials of cervical muscles in horses

Background: When surgical treatment of cervical vertebral malformation is considered, precise localization of compression sites is essential, but remains challenging. Magnetic motor evoked potentials (mMEP) from paravertebral muscles are useful in localizing spinal cord lesions, but no information about cervical muscle mMEP in horses is available yet. Therefore, the aim of this study was to determine the possibility, normal values, inter-and intra-observer agreement and factors that have an effect on cervical mMEP in healthy horses. Methods: Transcranial magnetic stimulation was performed on 50 normal horses and 4 (2 left, 2 right) muscle responses were recorded at the middle of each cervical vertebra (C1-C7) and additionally just caudal to C7 to evaluate cervical nerves (Cn) Cn1 to Cn8. Latency time and amplitude of the recorded mMEP were defined by both an experienced and an unexperienced operator. Results: Latency increased gradually from 14.2 +/- 1.38 ms for Cn3 to 17.7 +/- 1.36 ms for Cn8, was significantly influenced by cervical nerve (P < 0.01), gender (P = 0.02) and height (P = 0.03) and had a good intra-observer agreement. The smallest mean amplitude (4.35 +/- 2.37 mV) was found at Cn2, the largest (5.99 +/- 2.53 mV) at Cn3. Amplitude was only significantly influenced by cervical nerve (P < 0.01) and had a low intra-observer agreement. No significant effect of observer on latency (P = 0.88) or amplitude (P = 0.99) measurements was found. Conclusion: mMEP of cervical muscles in normal horses are easy to collect and to evaluate with limited intra-and inter-observer variation concerning amplitude and should be investigated in future studies in ataxic horses to evaluate its clinical value

Determination of magnetic motor evoked potential latency time cutoff values for detection of spinal cord dysfunction in horses

Background: Transcranial magnetic stimulation (TMS) and recording of magnetic motor evoked potentials (MMEP) can detect neurological dysfunction in horses but cutoff values based on confirmed spinal cord dysfunction are lacking. Objectives: To determine latency time cutoff for neurological dysfunction. Animals Five control horses and 17 horses with proprioceptive ataxia. Methods: Case-control study with receiver operating characteristic curve analysis, based on diagnostic imaging, TMS, and histopathological findings. Horses were included if all 3 examinations were performed. Results: Diagnostic imaging and histopathology did not show abnormalities in the control group but confirmed spinal cord compression in 14 of 17 ataxic horses. In the remaining 3 horses, histopathological lesions were mild to severe, but diagnostic imaging did not confirm spinal cord compression. In control horses, latency time values of thoracic and pelvic limbs were significantly lower than in ataxic horses (20 +/- 1 vs 34 +/- 16 milliseconds, P = .05; and 39 +/- 1 vs 78 +/- 26 milliseconds, P = .004). Optimal cutoff values to detect spinal cord dysfunction were 22 milliseconds (sensitivity [95% CI interval], 88% [73%-100%]; specificity, 100% [100%-100%]) in thoracic and 40 milliseconds (sensitivity, 94% [83%-100%]; specificity, 100% [100%-100%]) in pelvic limbs. To detect spinal cord dysfunction caused by compression, the optimal cutoff for thoracic limbs remained 22 milliseconds, while it increased to 43 milliseconds in pelvic limbs (sensitivity, 100% [100%-100%]; specificity, 100% [100%-100%] for thoracic and pelvic limbs). Conclusions and Clinical Importance: Magnetic motor evoked potential analysis using these cutoff values is a promising diagnostic tool for spinal cord dysfunction diagnosis in horses

Sonoprinting liposomes on tumor spheroids by microbubbles and ultrasound

Ultrasound-triggered drug-loaded microbubbles have great potential for drug delivery due to their ability to locally release drugs and simultaneously enhance their delivery into the target tissue. We have recently shown that upon applying ultrasound, nanoparticle-loaded microbubbles can deposit nanoparticles onto cells grown in 2D monolayers, through a process that we termed "sonoprinting". However, the rigid surfaces on which cell monolayers are typically growing might be a source of acoustic reflections and aspherical microbubble oscillations, which can influence microbubble-cell interactions. In the present study, we aim to reveal whether sonoprinting can also occur in more complex and physiologically relevant tissues, by using free-floating 3D tumor spheroids as a tissue model. We show that both monospheroids (consisting of tumor cells alone) and cospheroids (consisting of tumor cells and fibroblasts, which produce an extracellular matrix) can be sonoprinted. Using doxorubicin-liposome-loaded microbubbles, we show that sonoprinting allows to deposit large amounts of doxorubicin-containing liposomes to the outer cell layers of the spheroids, followed by doxorubicin release into the deeper layers of the spheroids, resulting in a significant reduction in cell viability. Sonoprinting may become an attractive approach to deposit drug patches at the surface of tissues, thereby promoting the delivery of drugs into target tissues

Diagnostic aid of transcranial magnetic stimulation in horses suspected of neurological gait abnormalities: a retrospective study

Movement disorders are often found in horses. A good clinical, neurological and orthopedic examination often reveals the cause of the abnormal gait. However, in more complex cases, assessing whether the horse has an orthopedic or neurological problem may be challenging. Between 01/10/2013 and 30/06/2015, 138 horses were examined by transcranial magnetic stimulation (TMS) because of gait abnormalities. The technique, which assesses the functionality of the descending motor tracts, was performed as described by Nollet et al. (2004). In 71 horses (51%), TMS was normal. Further examination revealed an orthopedic or conformational gait abnormality in 59 (83%) of these horses. However, in 12 cases (17%) a neurologic gait abnormality was diagnosed. Proprioceptive ataxia was suspected in 6 of them, 5 had a central or vestibular nervous problem and 1 had painful neck lesions. Of the 67 cases (48%) with an abnormal TMS, 30 owners declined further examinations. In the other 37 horses X-rays of the suspected region were taken and in 6 cases a contrast myelogram was performed in addition. Arthrosis of the facet joints of C5 to T11 (6 horses, 50%), cervical vertebral malformation (8 cases, 25%), trauma (6 cases, 19%: 2 fractures, 3 subluxations and 1 hematoma), neoplasia (1 case, 3%) and intervertebral disk disease (1 case, 3%) were found. So, in 32 cases (87%) spinal ataxia was confirmed by medical imaging. In conclusion, transcranial magnetic stimulation is a sensitive and specific aid in examining gait abnormalities in horses

The framing of migration by Flemish politicians : a comparative content analysis of newspapers, television, Facebook and Twitter

The current research focuses on the role of frame sponsors, more specifically politicians of the six main Flemish political parties (N-VA, Open Vld, CD&V, sp.a, Groen or Vlaams Belang), in framing the public debate about migration in the news as well as on social media. More specifically, we investigated the presence of four frames: the intruder frame, the victim frame, the wealth gap frame and the win-win frame (Van Gorp et al., 2018). We collected statements on migration or migrants made by Flemish politicians between 1 January 2016 and 30 June 2018 in four different types of media. We selected the five most read national newspapers: Het Laatste Nieuws, Het Nieuwsblad, De Standaard, De Morgen, and De Tijd. The television news items were collected from the 19h daily newscast VTM Nieuws (commercial broadcaster) and 19h daily newscast Het Journaal (public broadcaster VRT, Eén). On Twitter and Facebook, we included the official accounts of the political parties as well as the official accounts of their most important politicians (party leaders, Ministers and State Secretaries in the Federal and Flemish government, party experts on migration). In each of the four media, the units of registration are the statements by Flemish politicians containing at least one of the keywords “migration” or “migrant”. We only selected the verbatim quotes by politicians. The newspaper data were collected through the GoPress database, the TV items through the ENA (Elektronisch Nieuwsarchief) database, the Twitter data using the Twitter API, and the Facebook data by means of a manual scraping (due to practical limitations only the 50 most recent posts). The study was conducted by two independent coders. The intercoder reliability test resulted in strong kappa values (ranging from 0.617 to 1). We collected 1528 statements of 82 politicians representing the six parties; 47.9% (732) from N-VA, 27.1% (414) Vlaams Belang, 8.2% (125) Open Vld, 6.0% (91) CD&V, 5.9% (90) sp.a, and 5.0% (76) Groen. Importantly, only 245 of these statements contain one of the four researched frames (16.0%). This is not a surprise, since a lot of quotes are just factual and too short to contain framing or reasoning devices. The intruder frame is by far the most used frame (73.1%), followed by the victim frame (22.0%), wealth gap frame (3.7%), and win -win frame (1.2%). Vlaams Belang (38.8%) had the most framed statements, shortly followed by N-VA (35.9%). Both parties used the intruder frame the most. In contrast, the other four parties used the victim frame the most. We also found differences in frame use depending on the media type. The overrepresentation of the intruder frame on Twitter and television is related to the dominance of N -VA and Vlaams Belang accounts in these platforms. We also compared the framed statements in the media to the official views as carried out in the parties’ election programs (2014) which turn out to be more neutral, less emotional and comprise more alternatively framed statements about migration