Pilot ex vivo study on non-thermal ablation of human prostate adenocarcinoma tissue using boiling histotripsy.

Focused ultrasound technologies are of growing interest for noninvasive ablation of localized prostate cancer (PCa). Here we present the results of the first case study evaluating the feasibility of non-thermal mechanical ablation of human prostate adenocarcinoma tissue using the boiling histotripsy (BH) method on ex vivo tissue. High intensity focused ultrasound field was generated using a 1.5-MHz custom-made transducer with nominal F#=0.75. A sonication protocol of 734 W acoustic power, 10-ms long BH-pulses, 30 pulses per focal spot, 1 % duty cycle, and 1 mm distance between single foci was tested in an ex vivo human prostate tissue sample containing PCa. The protocol used here has been successfully applied in the previous BH studies for mechanical disintegration of ex vivo prostatic human tissue with benign hyperplasia. BH treatment was monitored using B-mode ultrasound. Post-treatment histologic analysis demonstrated BH produced liquefaction of the targeted tissue volume. BH treated benign prostate parenchyma and PCa had similar tissue fractionation into subcellular fragments. The results of the study demonstrated that PCa tumor tissue can be mechanically ablated using the BH method. Further studies will aim on optimizing protocol parameters to accelerate treatment while maintaining complete destruction of the targeted tissue volume into subcellular debris.

[A novel method for non-invasive mechanical ablation of prostate tumors using pulsed focused ultrasound].

AIM: of the study: demonstrate the feasibility of non-invasive mechanical disintegration of human prostate tissue using pulsed high-intensity focused ultrasound (pHIFU), a method termed boiling histotripsy. MATERIALS AND METHODS: An ultrasound experimental system was developed for producing localized mechanical lesions in ex vivo biological tissue samples under ultrasound guidance. A series of experiments was carried out to create small single-focus lesions (volume < 2 mm3) and one large lesion (volume > 50 mm3) in ex vivo prostate tissue samples. After irradiation, two samples were bisected to visualize the region of destruction; the other tissue samples were examined histologically. RESULTS: During pHIFU irradiation under B-mode ultrasound guidance, a region of increased echogenicity caused by formation of vapor-gas bubbles was visualized in the target region. After exposure, small and large lesions filled with a suspension of liquefied tissue were observed. Histological examination confirmed that the prostate tissue in the focal region was disintegrated into subcellular fragments. CONCLUSION: A pilot study showed the feasibility of using boiling histotripsy as a non-invasive method for treating prostate diseases.

Quantification of the hygroscopic effect of soot aging in the atmosphere: laboratory simulations.

We use a laboratory approach for the quantification of the water uptake by particles with varying amounts of sulfates to simulate the aging of fossil fuel combustion particles in the atmosphere. Diesel fuel and aviation kerosene laboratory-made soots are chosen as representative of the hydrophobic fraction of diesel and aircraft engine-emitted particulates and commercial carbon blacks are used as surrogates for industry emissions. The transformation of soot hydration properties from hydrophobic, through hydrophilic, to hygroscopic is demonstrated based on the amount of water uptake by the laboratory-produced EC soot covered by sulfates as the amount of sulfate increases. The mechanism of water/soot interaction changes from an adsorption on active sites to a water film formation and to the dissolution of water into the water-soluble sulfate, while the amount of sulfate increases. Laboratory simulations show that coverage of EC soot by organics diminishes the effect of sulfuric acid deposition. We demonstrate that the surface chemical properties and the size of primary particles affect the amount of water taken up by the soot particles and their aging in the atmosphere.

Water interaction with laboratory-simulated fossil fuel combustion particles.

To clarify the impact of fossil fuel combustion particles' composition on their capacity to take up water, we apply a laboratory approach in which the method of deposition of compounds, identified in the particulate coverage of diesel and aircraft engine soot particles, is developed. It is found that near-monolayer organic/inorganic coverage of the soot particles may be represented by three groups of fossil fuel combustion-derived particulate matter with respect to their Hansh's coefficients related to hydrophilic properties. Water adsorption measurements show that nonpolar organics (aliphatic and aromatic hydrocarbons) lead to hydrophobization of the soot surface. Acidic properties of organic compounds such as those of oxidized PAHs, ethers, ketones, aromatic, and aliphatic acids are related to higher water uptake, whereas inorganic acids and ionic compounds such as salts of organic acids are shown to be responsible for soot hydrophilization. This finding allows us to quantify the role of the chemical identity of soot surface compounds in water uptake and the water interaction with fossil fuel combustion particles in the humid atmosphere.

[Protein and DNA adsorption on dehydroxylated and aluminated silochromes]. / Adsorbtsiia belkov i DNK na degidroksilirovannykh i aliuminirovanykh silokhromakh.

A macroporous silica - silochrom - used for immobilization and purification of biopolymers was modified by dehydroxylation and alumination. The adsorption capacity of the modified silochroms for proteins and DNA is higher than that of the initial sorbent. The biopolymers adsorbed on aluminated silochrom are strongly attached to its surface.

[Urease immobilization on macroporous silicas]. / Immobilizatsiia ureazy na makroporistykh kremnezemakh.

Urease was immobilized on macroporous silicas using gamma-aminopropyl triethoxysilane and glutaraldehyde. The amount of protein on the surface, the structure of pores of the support and the purity of the initial enzyme were varied, the enzymic activity of the immobilized preparations being controlled. After the immobilization of sufficiently large quantities of the enzyme (about 3 mg protein per m2 support) about 35% of the specific activity was retained. The maximum activity per unit weight of the support was observed for silicagels and silochromes with the mean diameter of pores 70-90 nm and the specific surface area about 70 m2/g. The use of purified urease produced highly active preparations of the immobilized enzyme (17,000 U per g dry support). Freeze-drying of the immobilized enzyme in the presence of sorbitol yielded dry preparations retaining their activity.