Neuronavigation-Guided Transcranial Histotripsy (NaviTH) System.

OBJECTIVE: The goal of the work described here was to develop the first neuronavigation-guided transcranial histotripsy (NaviTH) system and associated workflow for transcranial ablation. METHODS: The NaviTH system consists of a 360-element, 700 kHz transmitter-receiver-capable transcranial histotripsy array, a clinical neuronavigation system and associated equipment for patient-to-array co-registration and therapy planning and targeting software systems. A workflow for NaviTH treatments, including pre-treatment aberration correction, was developed. Targeting errors stemming from target registration errors (TREs) during the patient-to-array co-registration process, as well as focal shifts caused by skull-induced aberrations, were investigated and characterized. The NaviTH system was used in treatments of two <96 h post-mortem human cadavers and in experiments in two excised human skullcaps. RESULTS: The NaviTH was successfully used to create ablations in the cadaver brains as confirmed in post-treatment magnetic resonance imaging A total of three ablations were created in the cadaver brains, and targeting errors of 9, 3.4 and 4.4 mm were observed in corpus callosum, septum and thalamus targets, respectively. Errors were found to be caused primarily by TREs resulting from transducer tracking instrument design flaws and imperfections in the treatment workflow. Transducer tracking instrument design and workflow improvements reduced TREs to <2 mm, and skull-induced focal shifts, following pre-treatment aberration correction, were 0.3 mm. Total targeting errors of the NaviTH system following the noted improvements were 2.5 mm. CONCLUSIONS: The feasibility of using the first NaviTH system in a human cadaver model has been determined. Although accuracy still needs to be improved, the proposed system has the potential to allow for transcranial histotripsy therapies without requiring active magnetic resonance treatment guidance.

Characterization of Blood-Brain Barrier Opening Induced by Transcranial Histotripsy in Murine Brains.

OBJECTIVE: Transcranial histotripsy has shown promise as a non-invasive neurosurgical tool, as it has the ability to treat a wide range of locations in the brain without overheating the skull. One important effect of histotripsy in the brain is the blood-brain barrier (BBB) opening (BBBO) at the ablation site, but there is a knowledge gap concerning the extent of histotripsy-induced BBBO. Here we describe induction of BBBO by transcranial histotripsy and use of magnetic resonance imaging (MRI) and histology to quantify changes in BBBO at the periphery of the histotripsy ablation zone over time in the healthy mouse brain. METHODS: An eight-element, 1 MHz histotripsy transducer with a focal distance of 32.5 mm was used to treat the brains of 23 healthy female BL6 mice. T1-gadolinium (T1-Gd) MR images were acquired immediately following histotripsy treatment and during each of the subsequent 4 wk to quantify the size and intensity of BBB leakage. RESULTS: The T1-Gd MRI results revealed that the hyperintense BBBO volume increased over the first week and subsided gradually over the following 3 wk. Histology revealed complete loss of tight junction proteins and blood vessels in the center of the ablation region immediately after histotripsy, partial recovery in the periphery of the ablation zone 1 wk following histotripsy and near-complete recovery of tight junction complex after 4 wk. CONCLUSION: These results provide the first evidence of transcranial histotripsy-induced BBBO and repair at the periphery of the ablation zone.

Histotripsy Treatment of Murine Brain and Glioma: Temporal Profile of Magnetic Resonance Imaging and Histological Characteristics Post-treatment.

OBJECTIVE: Currently, there is a knowledge gap in our understanding of the magnetic resonance imaging (MRI) characteristics of brain tumors treated with histotripsy to evaluate treatment response as well as treatment-related injuries. Our aim was to bridge this gap by investigating and correlating MRI with histological analysis after histotripsy treatment of mouse brain with and without brain tumors and evaluating the evolution of the histotripsy ablation zone on MRI over time. METHODS: An eight-element, 1 MHz histotripsy transducer with a focal distance of 32.5 mm was used to treat orthotopic glioma-bearing mice and normal mice. The tumor burden at the time of treatment was ∼5 mm3. T2, T2*, T1 and T1-gadolinium (Gd) MR images and histology of the brain were acquired on days 0, 2 and 7 for tumor-bearing mice and days 0, 2, 7, 14, 21 and 28 post-histotripsy for normal mice. RESULTS: T2 and T2* sequences most accurately correlated with histotripsy treatment zone. The treatment-induced blood products, T1 along with T2, revealed blood product evolution from oxygenated, de-oxygenated blood and methemoglobin to hemosiderin. And T1-Gd revealed the state of the blood-brain barrier arising from the tumor or histotripsy ablation. Histotripsy leads to minor localized bleeding, which resolves within the first 7 d as evident on hematoxylin and eosin staining. By day 14, the ablation zone could be distinguished only by the macrophage-laden hemosiderin, which resides around the ablation zone, rendering the treated zone hypo-intense on all MR sequences. CONCLUSION: These results provide a library of radiological features on MRI sequences correlated to histology, thus allowing for non-invasive evaluation of histotripsy treatment effects in in vivo experiments.

Quantitative Changes of Phenolic Compounds in Pine Twigs by Variety, Harvest Season, and Growing Region.

Three new phenolic compounds including pinosylvin 3-methoxy-5-O-ß-D-glucoside (PMG), taxiresinol 4'-O-α-L-rhamnoside (TRR), and lariciresinol 4'-O-α-L-rhamnoside (LRR) were first isolated and identified from red pine (Pinus densiflora Sieb. et Zucc.) twigs, together with four known compounds, such as (+)-catechin (CC), dihydromyricetin (DHM), dihydroquercetin 3-O-ß-D-glucoside (DHQG), and dihydroquercetin (DHQ). Additionally, the concentrations of seven phenolic compounds in pine twigs were measured by high-performance liquid chromatography based on cultivars, harvest seasons, and growing environments. Red and black pine twigs contain 379.33 and 308.83 mg/100 g of PMG as the predominant phenolics, respectively, and their contents were significantly higher in spring than in autumn. Red pine twigs contain higher amounts of three dihydroflavonols (DHM: 87.82, DHQG: 38.47, and DHQ: 68.07 mg/100 g) and two lignans (LRR: 15.63, TRR: 30.72 mg/100 g) than black pine twigs, except for higher (+)-CC level (21.88 mg/100 g) in black pine twigs. Two pine twigs had much higher flavonoid and lignan levels in the autumn than they had in the spring. Two pine twigs harvested in several different areas do not significantly differ in their phenolic compositions and contents. These results suggest that red pine twigs possessing phytochemical phenolics may be useful as potential sources for promoting human health.

Two-step aberration correction: application to transcranial histotripsy.

Objective: Phase aberration correction is essential in transcranial histotripsy to compensate for focal distortion caused by the heterogeneity of the intact skull bone. This paper improves the 2-step aberration correction (AC) method that has been previously presented and develops an AC workflow that fits in the clinical environment, in which the computed tomography (CT)-based analytical approach was first implemented, followed by a cavitation-based approach using the shockwaves from the acoustic cavitation emission (ACE).Approach:A 700 kHz, 360-element hemispherical transducer array capable of transmit-and-receive on all channels was used to transcranially generate histotripsy-induced cavitation and acquire ACE shockwaves. For CT-AC, two ray-tracing models were investigated: a forward ray-tracing model (transducer-to-focus) in the open-source software Kranion, and an in-house backward ray-tracing model (focus-to-transducer) accounting for refraction and the sound speed variation in skulls. Co-registration was achieved by aligning the skull CT data to the skull surface map reconstructed using the acoustic pulse-echo method. For ACE-AC, the ACE signals from the collapses of generated bubbles were aligned by cross-correlation to estimate the corresponding time delays.Main results:The performance of the 2-step method was tested with 3 excised human calvariums placed at 2 different locations in the transducer array. Results showed that the 2-step AC achieved 90 ± 7% peak focal pressure compared to the gold standard hydrophone correction. It also reduced the focal shift from 0.84 to 0.30 mm and the focal volume from 10.6 to 2.0 mm3on average compared to the no AC cases.Significance:The 2-step AC yielded better refocusing compared to either CT-AC or ACE-AC alone and can be implemented in real-time for transcranial histotripsy brain therapy.

Synthesis of Bridged Oxabicycles via Cascade Reactions involving O-Acyloxocarbenium Ion Intermediates.

Compared to related electrophilic species, O-acyloxocarbenium ions (AOIs) have been much less utilized in organic synthesis due to the lack of an efficient formation method. Here, we present a facile and simple approach for the generation of AOI from ester and acetal groups. Based on our AOI system with a pendant nucleophile, we obtained a unique bridged bicyclic system via an epoxonium-like transition state. The proposed mechanism is based on experimental and computational studies.

Quantitative Changes of Flavonol Glycosides from Pine Needles by Cultivar, Harvest Season, and Thermal Process.

Five flavonol glycosides including quercetin 3-O-ß-D-glucoside (QG), kaempferol 3-O-ß-D-glucoside (KG), quercetin 3-O-(6″-O-acetyl)-ß-D-glucoside (QAG), kaempferol 3-O-(6″-O-acetyl)-ß-D-glucoside (KAG), and quercetin 3-O-(3″-O-p-coumaroyl)-ß-D-glucoside (QCG) were isolated and purified from red pine (Pinus densiflora Sieb. et Zucc.) nee-dles, and identified by nuclear magnetic resonance and mass spectrometer spectral analyses. In addition, the quantification of the five flavonol glycosides in pine needles was performed by high-performance liquid chromatography analysis according to cultivar, growing district, harvest season, and thermal processing. The red pine needles had higher amounts of the five flavonol glycosides than the black pine needles except for QCG. There were no large differences in flavonoid composition and content among pine needles grown in three different areas. Levels of the five flavonol glycosides in red pine needles harvested during Spring ranged from 6.13 to 27.03 mg/100 g dry weight. Levels of two flavonol glycosides, QG and KG, gradually decreased with increasing harvest time, whereas the acylated flavonol glycoside, QCG, a predominant flavo-noid in pine needles, increased gradually with increasing harvest time. Two acetyl flavonol glycosides, QAG and KAG, increased steadily through Spring to Autumn, and then decreased gradually by Winter. Meanwhile heat treatments, such as roasting and steaming, increased the five flavonol glycosides during heating for 3 min, but then slowly decreased these when heating for 10 min. Microwave processing increased to some extent the five flavonol glycosides when heating for 3 min, and remained unchanged during the 10 min heating. These results suggest that the pretreated red pine needles with enhanced flavonoid content may be useful as potential sources for nutraceuticals and cosmeceuticals.

Discovery of Novel Small-Molecule Antiangiogenesis Agents to Treat Diabetic Retinopathy.

Diabetic retinopathy is the leading cause of blindness which is associated with excessive angiogenesis. Using the structure of wondonin marine natural products, we previously created a scaffold to develop a novel type of antiangiogenesis agent that possesses minimized cytotoxicity. To overcome its poor pharmaceutical properties, we further modified the structure. A new scaffold was derived in which the stereogenic carbon was changed to nitrogen and the 1,2,3-triazole ring was replaced by an alkyl chain. By comparing the bioactivity versus cytotoxicity, compound 31 was selected, which has improved aqueous solubility and an enhanced selectivity index. Mechanistically, 31 suppressed angiopoietin-2 (ANGPT2) expression induced by high glucose in retinal cells and exhibited in vivo antiangiogenic activity in choroidal neovascularization and oxygen-induced retinopathy mouse models. These results suggest the potential of 31 as a lead to develop antiangiogenic small-molecule drugs to treat diabetic retinopathy and as a chemical tool to elucidate new mechanisms of angiogenesis.

Stereotactic Transcranial Focused Ultrasound Targeting System for Murine Brain Models.

An inexpensive, accurate focused ultrasound stereotactic targeting method guided by pretreatment magnetic resonance imaging (MRI) images for murine brain models is presented. An uncertainty of each sub-component of the stereotactic system was analyzed. The entire system was calibrated using clot phantoms. The targeting accuracy of the system was demonstrated with an in vivo mouse glioblastoma (GBM) model. The accuracy was quantified by the absolute distance difference between the prescribed and ablated points visible on the pre treatment and posttreatment MR images, respectively. A precalibration phantom study ( N = 6 ) resulted in an error of 0.32 ± 0.31, 0.72 ± 0.16, and 1.06 ± 0.38 mm in axial, lateral, and elevational axes, respectively. A postcalibration phantom study ( N = 8 ) demonstrated a residual error of 0.09 ± 0.01, 0.15 ± 0.09, and 0.47 ± 0.18 mm in axial, lateral, and elevational axes, respectively. The calibrated system showed significantly reduced ( ) error of 0.20 ± 0.21, 0.34 ± 0.24, and 0.28 ± 0.21 mm in axial, lateral, and elevational axes, respectively, in the in vivo GBM tumor-bearing mice ( N = 10 ).

Index Coded Automatic Repeat Request (ARQ).

In this paper, an index-coded Automatic Repeat Request (ARQ) is studied in the perspectives of transmission efficiency and memory overhead. Motivated by reducing significant computational complexity from huge matrix inverse computation of random linear network coding, a near-to-optimal broadcasting scheme, called index-coded Automatic Repeat Request (ARQ) is proposed. The main idea is to consider the principal packet error pattern across all receivers. With the help of coded side information formed by successfully decoded packets associated with the dominant packet error pattern, it is shown that two contradictory performance metrics such as transmission efficiency and transmit (receive) cache memory size for index coding (decoding) can be enhanced with a reasonable trade-off. Specifically, the transmission efficiency of the proposed scheme is proved to be asymptotically optimal, and memory overhead is shown to be asymptotically close to the conventional ARQ scheme. Numerical results also validate the proposed scheme in the sense of memory overhead and transmission efficiency in comparison with the conventional ARQ scheme and the optimal scheme using random linear network coding.

Isolation, Identification, and Quantification of Tyrosinase and α-Glucosidase Inhibitors from UVC-Irradiated Mulberry (Morus alba L.) Leaves.

Methanol extracts from ultraviolet (UV) C-irradiated mulberry leaves (UVC-IML) exhibit stronger tyrosinase and α-glucosidase inhibitory activities than those from unirradiated mulberry leaves. Through a bioassay-guided fractionation and purification process, two oxyresveratrol derivatives, oxyresveratrol (ORT) and 4'-prenyloxyresveratrol (PORT), and six 2-arylbenzofuran derivatives [moracin B (MCB), moracin C (MCC), moracin M (MCM), moracin N (MCN), 6,5'-dimethoxymoracin M (DMMCM), and chalcomoracin (CMC)] were isolated from the methanol extract from UVC-IML. Their chemical structures were determined by UV, mass, and nuclear magnetic resonance spectrometry. ORT and PORT showed potent tyrosinase inhibitory activities with the half maximal inhibitory concentration (IC50) values of 0.57 and 0.90 µM, respectively, and CMC exhibited significant tyrosinase and α-glucosidase inhibitory activity with IC50 values of 5.61 and 6.00 µM, respectively. Levels of these eight compounds were increased significantly following irradiation compared with untreated mulberry leaves; ORTs increased approximately 4 fold and moracins increased 2~16 fold. These data suggest that UVC-IML may represent a promising source of nutraceuticals and cosmeceuticals for prevention of diabetes and skin aging.

Soft-Tissue Aberration Correction for Histotripsy.

Acoustic aberrations caused by natural heterogeneities of biological soft tissue are a substantial problem for histotripsy, a therapeutic ultrasound technique that uses acoustic cavitation to mechanically fractionate and destroy unwanted target tissue without damaging surrounding tissue. These aberrations, primarily caused by sound speed variations, result in severe defocusing of histotripsy pulses, thereby decreasing treatment efficacy. The gold standard for aberration correction (AC) is to place a hydrophone at the desired focal location to directly measure phase aberrations, which is a method that is infeasible in vivo. We hypothesized that the acoustic cavitation emission (ACE) shockwaves from the initial expansion of inertially cavitating microbubbles generated by histotripsy can be used as a point source for AC. In this study, a 500-kHz, 112-element histotripsy phased array capable of transmitting and receiving ultrasound on all channels was used to acquire ACE shockwaves. These shockwaves were first characterized optically and acoustically. It was found that the shockwave pressure increases significantly as the source changes from a single bubble to a dense cavitation cloud. The first arrival of the shockwave received by the histotripsy array was from the outer-most cavitation bubbles located closest to the histotripsy array. Hydrophone and ACE AC methods were then tested on ex vivo porcine abdominal tissue samples. Without AC, the focal pressure is reduced by 49.7% through the abdominal tissue. The hydrophone AC approach recovered 55.5% of the lost pressure. Using the ACE AC method, over 20% of the lost pressure was recovered, and the array power required to induce cavitation was reduced by approximately 31.5% compared to without AC. These results supported our hypothesis that the ACE shockwaves coupled with a histotripsy array with transmit and receive capability can be used for AC for histotripsy through soft tissue.

Construction and Characterization of Cell-Penetrating Peptide-Fused Fibroblast Growth Factor and Vascular Endothelial Growth Factor for an Enhanced Percutaneous Delivery System.

The exogenous administration of growth factors has been examined for treating wounds and such factors serve as cosmetic agents for skin regeneration. However, the topical application of growth factors is hampered by their limited percutaneous absorption. In this study, we genetically modified basic fibroblast growth factor (bFGF) and vascular endothelial growth factor-A (VEGF-A) using a cell-penetrating peptide to facilitate their permeation into skin and to avoid multiple steps in the chemical or physical modification of biomaterials. Low-molecular-weight protamine (LMWP)-fused bFGF and VEGF-A (LMWP-bFGF and LMWP-VEGF-A) were designed by serial polymerase chain reaction (PCR)-mediated addition of the LMWP codons onto the bFGF and VEGF-A genes and then produced in Escherichia coli. The purified LMWP-bFGF and LMWP-VEGF-A represented >90% of the total proteins, as determined by SDS-PAGE and densitometric quantification, and their actual molecular weights, determined by mass spectroscopy, were 19,026 and 15,715 Da, respectively, corresponding to the theoretical values. N-terminal amino acid sequencing analyses confirmed the N-terminal conjugation of LMWP to bFGF and VEGF-A. Immunoblotting analyses using antibodies against bFGF and VEGF-A, together with the proliferative effects of LMWP-bFGF and LMWP- VEGF-A on human keratinocytes and fibroblasts, demonstrated that the original biological activity of each growth factor was not altered by LMWP conjugation. In addition, the LMWP conjugation did not induce further cytotoxic effects on the skin cells, while the cell membrane-penetrating activities of LMWP-bFGF and LMWP-VEGF-A were significantly enhanced compared with the respective unconjugated growth factors. These results suggest that LMWP-bFGF and LMWP-VEGF-A can be used as effective topical therapeutic or cosmetic agents for skin regeneration and anti-aging treatments.

Preparation and In Vitro Evaluation of Elastic Nanoliposomes for Topical Delivery of Highly Skin-Permeable Growth Factors.

Percutaneous delivery of growth factors is often used to treat wounds, and for cosmetic purposes, as a way of accelerating healing and skin regeneration, respectively. However, the therapeutic effects of growth factors are diminished by their poor absorption when delivered percutaneously, in addition to their rapid degradation by proteinases. To overcome these obstacles, we constructed two skin-permeable compounds. Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor-A (VEGF-A) were both genetically paired with low-molecular-weight protamine (LMWP), to yield the compounds LMWP-bFGF and LMWP-VEGF-A, respectively. The molecular weights and N-terminal amino acid sequences of LMWP-bFGF and LMWP-VEGF-A confirmed that the N-terminus-specific conjugation of LMWP with bFGF and VEGF-A had been successful. The biological abilities of the native factors to stimulate human fibroblast (CCD-986sk) and endothelial cell proliferation were preserved. Both compounds significantly promoted wound (scratch) recovery and enhanced procollagen type I C-peptide synthesis in CCD-986sk cells (to levels 184 and 133% those of the native compounds, respectively). The LMWP-conjugated growth factors were significantly more permeable than the native forms (by 7.29- and 29.22-fold, respectively). Finally, encapsulation of the compounds in positively charged elastic nanoliposomes (115 ± 1.54 nm in diameter with a zeta potential of 57.2 ± 3.05 mV) further improved both permeation and stability. Thus, nanoliposomes loaded with LMWP-conjugated growth factors are expected to enhance skin regeneration; the materials will find applications in wound-healing therapies and anti-wrinkle cosmetics.

Multispectral photoacoustic microscopy of lipids using a pulsed supercontinuum laser.

We demonstrate optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue between 1050-1714 nm using a pulsed supercontinuum laser based on a large-mode-area photonic crystal fiber. OR-PAM experiments of lipid-rich samples show the expected optical absorption peaks near 1210 and 1720 nm. These results show that pulsed supercontinuum lasers are promising for OR-PAM applications such as label-free histology of lipid-rich tissue and imaging small animal models of disease.

Revisiting Degrees of Freedom of Full-Duplex Systems with Opportunistic Transmission: An Improved User Scaling Law.

It was recently studied how to achieve the optimal degrees of freedom (DoF) in a multi-antenna full-duplex system with partial channel state information (CSI). In this paper, we revisit the DoF of a multiple-antenna full-duplex system using opportunistic transmission under the partial CSI, in which a full-duplex base station having M transmit antennas and M receive antennas supports a set of half-duplex mobile stations (MSs) having a single antenna each. Assuming no self-interference, we present a new hybrid opportunistic scheduling method that achieves the optimal sum DoF under an improved user scaling law. Unlike the state-of-the-art scheduling method, our method is designed in the sense that the scheduling role between downlink MSs and uplink MSs is well-balanced. It is shown that the optimal sum DoF of 2 M is asymptotically achievable provided that the number of MSs scales faster than SNR M , where SNR denotes the signal-to-noise ratio. This result reveals that, in our full-duplex system, better performance on the user scaling law can be obtained without extra CSI, compared to the prior work that showed the required user scaling condition (i.e., the minimum number of MSs for guaranteeing the optimal DoF) of SNR 2 M - 1 . Moreover, the average interference decaying rate is analyzed. Numerical evaluation is performed to not only validate our analysis but also show superiority of the proposed method over the state-of-the-art method.

Linear Algebraic Beamforming Design for Multiuser MISO Interference Channels: A Reduction in Search Space Dimension.

Near-optimal transmit beamformers are designed for multiuser multiple-input single-output interference channels with slowly time-varying block fading. The main contribution of this article is to provide a method for deriving closed-form solutions to effective beamforming in both low and high signal-to-noise ratio regimes. The proposed method basically leverages side information obtained from the channel correlation between adjacent coding blocks. More specifically, our methodology is based on a linear algebraic approach, which is more efficient than the optimal scheme based on the Gaussian input in the sense of reducing the average number of search space dimensions for designing the near-optimal transmit beamformers. The proposed method is shown to exhibit near-optimal performance via computer simulations in terms of the average sum-rate.

Simulation and Damage Analysis of an Accidental Jet Fire in a High-Pressure Compressed Pump Shelter.

BACKGROUND: As one of the most frequently occurring accidents in a chemical plant, a fire accident may occur at any place where transfer or handling of combustible materials is routinely performed. METHODS: In particular, a jet fire incident in a chemical plant operated under high pressure may bring severe damage. To review this event numerically, Computational Fluid Dynamics methodology was used to simulate a jet fire at a pipe of a compressor under high pressure. RESULTS: For jet fire simulation, the Kemeleon FireEx Code was used, and results of this simulation showed that a structure and installations located within the shelter of a compressor received serious damage. CONCLUSION: The results confirmed that a jet fire may create a domino effect that could cause an accident aside from the secondary chemical accident.