In vivo Biodistribution of Radiolabeled Acoustic Protein Nanostructures

Purpose: Contrast-enhanced ultrasound plays an expanding role in oncology, but its applicability to molecular imaging is hindered by a lack of nanoscale contrast agents that can reach targets outside the vasculature. Gas vesicles (GVs)—a unique class of gas-filled protein nanostructures—have recently been introduced as a promising new class of ultrasound contrast agents that can potentially access the extravascular space and be modified for molecular targeting. The purpose of the present study is to determine the quantitative biodistribution of GVs, which is critical for their development as imaging agents. Procedures: We use a novel bioorthogonal radiolabeling strategy to prepare technetium-99m-radiolabeled ([99mTc])GVs in high radiochemical purity. We use single photon emission computed tomography (SPECT) and tissue counting to quantitatively assess GV biodistribution in mice. Results: Twenty minutes following administration to mice, the SPECT biodistribution shows that 84 % of [99mTc]GVs are taken up by the reticuloendothelial system (RES) and 13 % are found in the gall bladder and duodenum. Quantitative tissue counting shows that the uptake (mean ± SEM % of injected dose/organ) is 0.6 ± 0.2 for the gall bladder, 46.2 ± 3.1 for the liver, 1.91 ± 0.16 for the lungs, and 1.3 ± 0.3 for the spleen. Fluorescence imaging confirmed the presence of GVs in RES. Conclusions: These results provide essential information for the development of GVs as targeted nanoscale imaging agents for ultrasound

In vivo Biodistribution of Radiolabeled Acoustic Protein Nanostructures

Purpose: Contrast-enhanced ultrasound plays an expanding role in oncology, but its applicability to molecular imaging is hindered by a lack of nanoscale contrast agents that can reach targets outside the vasculature. Gas vesicles (GVs)—a unique class of gas-filled protein nanostructures—have recently been introduced as a promising new class of ultrasound contrast agents that can potentially access the extravascular space and be modified for molecular targeting. The purpose of the present study is to determine the quantitative biodistribution of GVs, which is critical for their development as imaging agents. Procedures: We use a novel bioorthogonal radiolabeling strategy to prepare technetium-99m-radiolabeled ([99mTc])GVs in high radiochemical purity. We use single photon emission computed tomography (SPECT) and tissue counting to quantitatively assess GV biodistribution in mice. Results: Twenty minutes following administration to mice, the SPECT biodistribution shows that 84 % of [99mTc]GVs are taken up by the reticuloendothelial system (RES) and 13 % are found in the gall bladder and duodenum. Quantitative tissue counting shows that the uptake (mean ± SEM % of injected dose/organ) is 0.6 ± 0.2 for the gall bladder, 46.2 ± 3.1 for the liver, 1.91 ± 0.16 for the lungs, and 1.3 ± 0.3 for the spleen. Fluorescence imaging confirmed the presence of GVs in RES. Conclusions: These results provide essential information for the development of GVs as targeted nanoscale imaging agents for ultrasound

Fundamentals and developments in fluorescence-guided cancer surgery

Fluorescence-guided surgery using tumour-targeted imaging agents has emerged over the past decade as a promising and effective method of intraoperative cancer detection. An impressive number of fluorescently labelled antibodies, peptides, particles and other molecules related to cancer hallmarks have been developed for the illumination of target lesions. New approaches are being implemented to translate these imaging agents into the clinic, although only a few have made it past early-phase clinical trials. For this translational process to succeed, target selection, imaging agents and their related detection systems and clinical implementation have to operate in perfect harmony to enable real-time intraoperative visualization that can benefit patients. Herein, we review key aspects of this imaging cascade and focus on imaging approaches and methods that have helped to shed new light onto the field of intraoperative fluorescence-guided cancer surgery with the singular goal of improving patient outcomes

Dental Trauma First-Aid Knowledge and Attitudes of Physical Education Teachers: A Systematic Review and Meta-Analysis of the Literature with Meta-Regressions

The main objective of the present review is to evaluate the knowledge and attitudes of physical education (PE) teachers concerning dental trauma first-aid through a systematic appraisal of the literature, meta-analysis and meta-regressions. The entire content of PubMed and ISI/Web of Science was mined. Eligibility criteria for selecting studies were studies evaluating dental trauma first-aid knowledge and/or attitudes and/or the effectiveness of mouthguards use by PE teachers. Articles written in any language and published or accepted by peer-reviewed journals were considered. Methodological quality was assessed using an adapted version of the Downs and Black instrument. Of 15 selected articles, three were of strong quality, three were moderate, and the remaining nine were rated as weak. The majority of studies showed that PE teachers had an inadequate knowledge of the initial management of dental trauma. Specifically, there was a lack of knowledge concerning an appropriate washing and transporting medium and the extra-alveolar period of an avulsed tooth. Due to the inadequate knowledge of PE teachers regarding dental trauma management, specific education should be added to PE classes to improve the emergency treatment of dental injuries

Superiorized Photo-Acoustic Non-NEgative Reconstruction (SPANNER) for Clinical Photoacoustic Imaging

Photoacoustic (PA) imaging can revolutionize medical ultrasound by augmenting it with molecular information. However, clinical translation of PA imaging remains a challenge due to the limited viewing angles and imaging depth. Described here is a new robust algorithm called Superiorized Photo-Acoustic Non-NEgative Reconstruction (SPANNER), designed to reconstruct PA images in real-time and to address the artifacts associated with limited viewing angles and imaging depth. The method utilizes precise forward modeling of the PA propagation and reception of signals while accounting for the effects of acoustic absorption, element size, shape, and sensitivity, as well as the transducer's impulse response and directivity pattern. A fast superiorized conjugate gradient algorithm is used for inversion. SPANNER is compared to three reconstruction algorithms: delay-and-sum (DAS), universal back-projection (UBP), and model-based reconstruction (MBR). All four algorithms are applied to both simulations and experimental data acquired from tissue-mimicking phantoms, ex vivo tissue samples, and in vivo imaging of the prostates in patients. Simulations and phantom experiments highlight the ability of SPANNER to improve contrast to background ratio by up to 20 dB compared to all other algorithms, as well as a 3-fold increase in axial resolution compared to DAS and UBP. Applying SPANNER on contrast-enhanced PA images acquired from prostate cancer patients yielded a statistically significant difference before and after contrast agent administration, while the other three image reconstruction methods did not, thus highlighting SPANNER's performance in differentiating intrinsic from extrinsic PA signals and its ability to quantify PA signals from the contrast agent more accurately.11Nsciescopu

The effects of Ramadan intermittent fasting on sleep-wake behaviour and daytime sleepiness in team sport referees

The aim of the present study was to evaluate the impact of Ramadan fasting on sleep quality and daytime sleepiness in team sport referees. Seventy-eight male amateur team sport referees (age: 31.1 ± 10.8 years) participated in this study. Participants responded to the Arabic version of the Pittsburgh Sleep Quality Index (PSQI) and the Epworth sleepiness scale (ESS) questionnaires before (10-days prior) and during (last 7-days) the month of Ramadan. PSQI and ESS scores increased significantly during Ramadan (both p < .001, ES = 0.56 and 0.54, respectively) with 83.3% of participants scoring ≥5 in the PSQI. The percentage of participants suffering from severe excessive daytime sleepiness (ESS score ≥ 16) was 3.8% before vs. 7.7% during Ramadan (p < 0.001). Sleep duration decreased by ~ 1 h during Ramadan (p < .001, ES = 0.61) and was associated with a delay in bedtime of ~ 2 h (p < 0.001, ES = 0.7) and of wake-up time of ~ 1 h (p < 0.001, ES = 0.5). The score for daytime dysfunction and subjective sleep perception, as components of the PSQI, increased (both p < 0.001; ES = 0.79, ES = 0.57, respectively), whereas the score for the use of sleep medication decreased during vs. before Ramadan (p = 0.041, ES = 0.47). Ramadan fasting impaired sleep quality and increased daytime sleepiness in team sport referees. Future studies, using objective assessment tools, are warranted

Development of prostate specific membrane antigen targeted ultrasound microbubbles using bioorthogonal chemistry

<div><p>Prostate specific membrane antigen (PSMA) targeted microbubbles (MBs) were developed using bioorthogonal chemistry. Streptavidin-labeled MBs were treated with a biotinylated tetrazine (MB_Tz) and targeted to PSMA expressing cells using <i>trans</i>-cyclooctene (TCO)-functionalized anti-PSMA antibodies (TCO-anti-PSMA). The extent of MB binding to PSMA positive cells for two different targeting strategies was determined using an <i>in vitro</i> flow chamber. The initial approach involved pretargeting, where TCO-anti-PSMA was first incubated with PSMA expressing cells and followed by MB_Tz, which subsequently showed a 2.8 fold increase in the number of bound MBs compared to experiments performed in the absence of TCO-anti-PSMA. Using direct targeting, where TCO-anti-PSMA was linked to MB_Tz prior to initiation of the assay, a 5-fold increase in binding compared to controls was observed. The direct targeting approach was subsequently evaluated <i>in vivo</i> using a human xenograft tumor model and two different PSMA-targeting antibodies. The US signal enhancements observed were 1.6- and 5.9-fold greater than that for non-targeted MBs. The lead construct was also evaluated in a head-to-head study using mice bearing both PSMA positive or negative tumors in separate limbs. The human PSMA expressing tumors exhibited a 2-fold higher US signal compared to those tumors deficient in human PSMA. The results demonstrate both the feasibility of preparing PSMA-targeted MBs and the benefits of using bioorthogonal chemistry to create targeted US probes.</p></div

Representative US images showing targeted tumor localization of MB_Tz-TCO-ARP in PC-3 tumor xenografts.

<p>The PSMA⁺ or PSMA⁻tumor were imaged 4 min after intravenous administration of MB_Tz-TCO-ARP followed by imaging the other tumor. The images show qualitatively higher US signal in the PSMA⁺ tumor (a) compared to the signal found in the PSMA⁻tumor (b). Images are transverse color-coded parametric images overlaid on a non-linear contrast mode US image with whole PC-3 xenograft tumor (green outline) in the field of view. Scale bar = 2mm; dTE = differential targeted enhancement.</p

Differential targeted enhancement (dTE) signal obtained after accumulation of MB_Tz-TCO-ARP in PC-3 xenograft tumors.

<p>Data are average signal enhancements obtained when imaging PSMA⁺ PC-3 tumors (n = 5) compared to PSMA⁻PC-3 tumors (n = 7). Signal obtained from accumulation of MB_Tz-TCO-ARP in PSMA⁺ PC-3 tumors was significantly higher than that in PSMA⁻PC-3 tumors (<i>P</i> = 0.002). Statistical analysis was performed using one-way ANOVA.</p

Representative US images showing targeted tumor localization of MB_Tz targeted with two different anti-PSMA antibodies.

<p>Direct targeting MB_Tz constructs are shown: MB_Tz-TCO-J591 (left bottom) and MB_Tz-TCO-ARP (right bottom). Images were first acquired 4 min after intravenous administration of non-targeted MB_Tz (top left and right), followed by the targeted constructs. Each pair of images (top/bottom) are from the same mouse and field of view. Images are transverse color-coded parametric images overlaid on a non-linear contrast mode US image with the whole LNCaP xenograft tumor (green outline) in the field of view. dTE = differential targeted enhancement. Complete imaging data can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176958#pone.0176958.s005" target="_blank">S5 File</a>.</p