On the rigidity of four hundred Pickering-stabilised microbubbles

This study explores the rigidity of Pickering-stabilised microbubbles subjected to low-amplitude ultrasound. Such microbubbles might be suitable ultrasound contrast agents. Using an adapted Rayleigh-Plesset equation, we modelled the dynamics of microbubbles with a 7.6-N m−1 shell stiffness under 1-MHz, 0.2-MPa sonication. Such dynamics were observed experimentally, too, using high-speed photography. The maximum expansions were agreeing with those predicted for Pickering-stabilised microbubbles. Subjecting microbubbles to multiple time- delayed pulses yielded the same result. We conclude that Pickering-stabilised microbubbles remain very stable at low acoustic amplitudes.

Differentiation of malignant from non-malignant portal vein thrombosis in liver cirrhosis: the challenging dilemma

Background PVT is an ultrasonographic finding in up to 8% of patients with liver cirrhosis. Once hepatocellular carcinoma has occurred as the final station in liver cirrhosis, the risk of PVT rises to 40%. Benign and malignant PVT can occur in patients with liver cirrhosis, and it is important to differentiate the nature of PVT as it has a great impact on patient’s management and outcome. Diagnosis Confirming portal vein thrombosis and extension by abdominal ultrasound, contrast-enhanced USG, CT, or MRI. Malignant criteria of PVT are pulsatile pattern in Doppler and heterogeneous contrast enhancement, which are especially seen at the arterial phase, neovascularity within PVT, portal vein thrombus with a diameter of > 23 mm while in benign thrombus, PV diameter does not exceed 20 mm. Visible hypervascular tumor is in close proximity to PVT. Conclusion It is not uncommon to find portal vein thrombosis in patients with liver cirrhosis, despite the fact that malignant variant is the most frequent, but efforts should be gathered to exclude benign PVT which may change the management of the patients dramatically.

Nanosized Contrast Agents in Ultrasound Molecular Imaging

Applying nanosized ultrasound contrast agents (nUCAs) in molecular imaging has received considerable attention. nUCAs have been instrumental in ultrasound molecular imaging to enhance sensitivity, identification, and quantification. nUCAs can achieve high performance in molecular imaging, which was influenced by synthetic formulations and size. This review presents an overview of nUCAs from different synthetic formulations with a discussion on imaging and detection technology. Then we also review the progress of nUCAs in preclinical application and highlight the recent challenges of nUCAs.

Effects of Ultrasound Contrast Agent-Mediated Nerve Growth Factor on Apoptosis of Retinal Ganglion Cells in Mice with Glaucoma

With an increasing incidence in recent years, glaucoma (GL) has gradually become a global public health problem for humans of all ages. Nerve growth factor (NGF) eye drops, with well-documented stable effect in the treatment of GL, can be potentiated by the administration of NGF drugs via ultrasound contrast agent (UCA). This study analyzed the efficacy of NGF+UCA on GL mice and the influencing mechanism on retinal ganglion cells and further explored the pathological changes of GL mice under different UCA irradiation duration. In this study, we established GL mouse models and treated the mouse with NGF+UCA. The effect of NGF+UCA on intraocular pressure in mice was observed; the flash visual evoked potential of mice was compared; the changes of retinal structure, inflammation index, and oxidative stress index were observed, and autophagic protein levels were tested. Finally, the influence of UCA irradiation duration on GL symptoms was observed. The results showed that the intraocular pressure of mice decreased greatly, while their flash visual evoked potential and nervous layer of retina increased, and their ganglion cells showed stronger proliferation activity and weaker apoptosis and autophagy, indicating that UCA-mediated NGF can strongly improve the pathological condition of GL mice. In addition, PI3K/AKT pathway-associated proteins were inhibited in retina under the intervention of NGF+UCA, which further suggests that the influence of UCA-mediated NGF on GL is achieved by inhibiting autophagy of retinal ganglion cells and enhancing their apoptosis via the PI3K/AKT signaling pathway. Moreover, we found that in the treatment of GL, three weeks of UCA irradiation and six weeks caused no significant difference in the pathological manifestations and ganglion cells of mice, while after six weeks of irradiation, the level of NLRP3 in mice increased. In conclusion, UCA-mediated NGF can significantly improve the pathological condition of GL mice and improve the apoptosis of retinal ganglion cells by inhibiting autophagy, which is associated with the inhibition of the PI3K/AKT signal pathway. In terms of selection of UCA irradiation duration, three weeks of irradiation is enough to yield good clinical results.

Detecting insulitis in type 1 diabetes with ultrasound phase-change contrast agents

Type 1 diabetes (T1D) results from immune infiltration and destruction of insulin-producing β cells within the pancreatic islets of Langerhans (insulitis). Early diagnosis during presymptomatic T1D would allow for therapeutic intervention prior to substantial β-cell loss at onset. There are limited methods to track the progression of insulitis and β-cell mass decline. During insulitis, the islet microvasculature increases permeability, such that submicron-sized particles can extravasate and accumulate within the islet microenvironment. Ultrasound is a widely deployable and cost-effective clinical imaging modality. However, conventional microbubble contrast agents are restricted to the vasculature. Submicron nanodroplet (ND) phase-change agents can be vaporized into micron-sized bubbles, serving as a microbubble precursor. We tested whether NDs extravasate into the immune-infiltrated islet microenvironment. We performed ultrasound contrast-imaging following ND infusion in nonobese diabetic (NOD) mice and NOD;Rag1ko controls and tracked diabetes development. We measured the biodistribution of fluorescently labeled NDs, with histological analysis of insulitis. Ultrasound contrast signal was elevated in the pancreas of 10-wk-old NOD mice following ND infusion and vaporization but was absent in both the noninfiltrated kidney of NOD mice and the pancreas of Rag1ko controls. High-contrast elevation also correlated with rapid diabetes onset. Elevated contrast was also observed as early as 4 wk, prior to mouse insulin autoantibody detection. In the pancreata of NOD mice, infiltrated islets and nearby exocrine tissue were selectively labeled with fluorescent NDs. Thus, contrast ultrasound imaging with ND phase-change agents can detect insulitis prior to diabetes onset. This will be important for monitoring disease progression, to guide and assess preventative therapeutic interventions for T1D.