Clear Imaging Research Articles

A Nucleoside Derivative 5-Vinyluridine (VrU) for Imaging RNA in Cells and Animals.

In the present study, we used a nucleoside derivative 5-vinyluridine (VrU) for labeling during cell division and for tumor imaging in living mice. We demonstrated that the functional nucleoside bearing a 5-vinyl group is metabolically incorporated into cellular RNA and can be used to image RNA using a Diels-Alder reaction. The reagent allows for simultaneous and clear imaging of DNA and RNA in mammalian cells at single-cell resolution. We extended this approach to observe DNA and RNA behaviors in several basic stages of cell division. We further demonstrated that the derivative can be used for fluorescence imaging of tumor in live mice.

Comparison and Assessment of Regional and Global Land Cover Datasets for Use in CLASS over Canada

Global land cover information is required to initialize land surface and Earth system models. In recent years, new land cover (LC) datasets at finer spatial resolutions have become available while those currently implemented in most models are outdated. This study assesses the applicability of the Climate Change Initiative (CCI) LC product for use in the Canadian Land Surface Scheme (CLASS) through comparison with finer resolution datasets over Canada, assisted with reference sample data and a vegetation continuous field tree cover fraction dataset. The results show that in comparison with the finer resolution maps over Canada, the 300 m CCI product provides much improved LC distribution over that from the 1 km GLC2000 dataset currently used to provide initial surface conditions in CLASS. However, the CCI dataset appears to overestimate needleleaf forest cover especially in the taiga-tundra transition zone of northwestern Canada. This may have partly resulted from limited availability of clear sky MEdium Resolution Imaging Spectrometer (MERIS) images used to generate the CCI classification maps due to the long snow cover season in Canada. In addition, changes based on the CCI time series are not always consistent with those from the MODIS or a Landsat-based forest cover change dataset, especially prior to 2003 when only coarse spatial resolution satellite data were available for change detection in the CCI product. It will be helpful for application in global simulations to determine whether these results also apply to other regions with similar landscapes, such as Eurasia. Nevertheless, the detailed LC classes and finer spatial resolution in the CCI dataset provide an improved reference map for use in land surface models in Canada. The results also suggest that uncertainties in the current cross-walking tables are a major source of the often large differences in the plant functional types (PFT) maps, and should be an area of focus in future work.

Imaging the Pore Structure in Geomaterials Using Rhodamine B Covalently Decorated Magnetic Nanoparticles

There has been a recent booming development of multifunctional nanoparticles with precisely defined materials and an accompanying abundance of synthesis methods. However, developing a rational strategy to choose the proper nanoparticle and optimal synthesis method for geological applications remains a bottleneck. Here, a rhodamine B covalently decorated Fe3O4 nanoparticle was studied to assess its application as a novel bifunctional nanomarker for the optical imaging of the pore structure in geomaterials. With this bifunctional nanomarker, we were able to combine magnetic injection, which provides a simple and non-destructive way of introducing the nanomarker into rocks, with fluorescence imaging techniques, which provide clear contrast imaging between geomaterials (black) and porosity (bright). The covalent bifunctional nanomarker exhibits higher fluorescence and less leakage of the fluorescence dye than those produced by the physical coating method. It offers not only a more practical and reliable nanomarker for the analysis of the pore structure in geomaterials but also contributes to nanomaterial-oriented research for various geological applications.

Silica/gold nanoplatform combined with a thermosensitive gel for imaging-guided interventional therapy in PDX of pancreatic cancer

Imaging-guided interventional therapy is a promising means of minimally invasive and targeted drug delivery for patients with advanced pancreatic cancer. The effectiveness of the method depends on clear imaging and complete removal of cancer cells, especially peripheral infiltration and distant metastasis, to prevent recurrence. We synthesized hollow mesoporous silica-based nanoparticles, Gem-PFH-Au star-HMS-IGF1, with gemcitabine (Gem) and perfluorohexane (PFH) encapsulated internally, gold nanostars (Au NSs) and insulin-like growth factor-1 (IGF1) modified outwardly, to enhance multimode ultrasound (US)/computed tomography (CT)/photoacoustic (PA)/thermal imaging, guide photothermal therapy, and evaluate the effect in real time. We also prepared a type of thermosensitive gel that solidified at body temperature to facilitate the controlled release of Gem and achieve a single-administration interventional therapy. A patient-derived xenograft (PDX) mouse model was established in this study. The PDX was precisely ablated by photothermal therapy under the guidance of US/CT/PA imaging, and the residual pancreatic cancer cells were completely inhibited by Gem to prevent recurrence. This strategy ingeniously simulated the approach of surgical resection and postoperative chemotherapy in clinical procedures to treat malignancy and paves the way for interventional therapy.

Development of Weak Signal Recognition and an Extraction Algorithm for Raman Imaging.

Improving time resolution of Raman imaging is essential for the observation of dynamic processes involved in interfacial catalysis and biological systems. The crucial step is how to recognize and extract weak Raman signals overwhelmed in the strong noise under the low signal-to-noise ratio (SNR) condition. Here, by exploring the relationship between the SNR of a single Raman spectrum and the structural similarity (SSIM; the key parameter evaluating the image quality) of the whole image, we determined a semiempirical threshold with SNR = 0 dB for clear imaging for the first time. Therefore, we proposed one signal processing algorithm for fast Raman imaging by reconstructing the Raman spectrum with the aid of weak signal processing: extracting the reliable Raman signal of the target under the low SNR and then determining the suitable scanning time to obtain the Raman image with a trustworthy image quality. In the first step, fast Fourier transform (FFT), least squares, and 2-D median filter are sequentially applied to improve the SNR of each raw Raman spectrum. In the second step, a local SNR evaluation strategy is developed to predict image quality as well as the determination of clear imaging. The proposed method was successfully applied to the fast imaging of the cell under the low SNR condition.

Millimeter-Wave Sparse Imaging for Concealed Objects Based on Sparse Range Migration Algorithm

To relieve the system cost in densely sampling when applying the millimeter-wave (MMW) synthetic aperture radar (SAR) technique for imaging applications, an MMW sparse imaging method is presented by the combination of the under-sampling scheme in space and the following sparse imaging algorithm. Different from the requirement on sub-wavelength sampling interval by Nyquist law, the system only needs to collect a random subset of spatial samples. To transform the spatial samples into wavenumber domain, a sparse range migration algorithm (SRMA) is proposed to realize MMW sparse imaging by embedding the matrix completion (MC) technique into classical RMA. In light of the relationship of Fourier transform between the scattering coefficients and the wavenumber-domain echo, the proposed algorithm utilizes the atomic norm minimization to fulfill the MC from the small set of wavenumber-domain entries to their full data matrix. The experiments are conducted by a wideband MMW transceiver mounted on a linear trajectory for imaging two specimens with different kinds of cover. Their clear imaging contrast of azimuth-range profiles is obtained through SRMA under different under-sampling conditions and RMA with fully sampled data, and verify the effectiveness of the proposed method.

Deep learning assisted portable IR active imaging sensor spots and identifies live humans through fire

Achieving clear imaging through fire is a highly pursued goal and various active field-portable devices have been recently proposed to improve the capabilities of existing thermographic cameras. Here we combine an Infrared active imaging sensor and artificial intelligence to obtain automatic detection of people hidden behind flames. We show the successful use of a pre-trained Convolutional Neural Network in recognizing a static or moving person through fire when this is imaged by the proposed system. Remarkably, the network is able to detect the person even in the case the imaging system we propose cannot reject the flame disturbance in full, thus improving its robustness. These results pave the way to the development of automatic surveillance systems able to generate alerts in the case a fire spreads and persons are detected inside rooms invaded by flames, without relying on the subjective human interpretation of the videos.

Triptolide-induced hepatotoxicity via apoptosis and autophagy in zebrafish.

Previous research about the development of triptolide (TP) as a natural active compound has often focused on hepatotoxicity. Among its various mechanisms, autophagy and apoptosis are two important signaling pathways. In this study, we used zebrafish to establish a TP-induced hepatotoxicity model, and investigated the roles of autophagy and apoptosis in the progress of liver injury. Zebrafish exposed to TP showed increased mortality and malformation because of the increased drug dose and duration of exposure. Meanwhile, we found that TP induced liver injury in a time- and dose-dependent manner, which was observed as a reduction in liver area, slow yolk absorption, upregulation of transaminase and local neurosis. With the application of the high-content imaging system (HCIS) technique in liver 3D imaging in vivo, clear imaging of the zebrafish liver was achieved. The results showed a decrease in volume and location of necrosis in the liver after TP exposure. Increased expression of inflammatory cytokines genes tumor necrosis factor (Tnf)α, Il1β and Il6 were shown, particularly Tnfα. The Fas-Caspase8 signaling pathway was activated. The apoptosis-related gene Bcl-2 was increased, and Bax, Caspase9 and Caspase3 were increased. However, autophagy related genes Beclin1, Atg5, Atg3 and Lc3 were increased more significantly, and the changes of Beclin1 and Atg5 were the most severe. This study successfully established a TP-induced zebrafish hepatotoxicity model and applied the HCIS technique in a zebrafish hepatotoxicity study. The result indicated Fas might be the main target of TP-induced hepatotoxicity. Autophagy played a more important role than apoptosis and was characterized by the overexpression of Beclin1 and Atg5.

Fast optical wavefront engineering for controlling light propagation in dynamic turbid media

While propagating inside the strongly scattering biological tissue, photons lose their incident directions beyond one transport mean free path (TMFP, [Formula: see text]1 millimeter (mm)), which makes it challenging to achieve optical focusing or clear imaging deep inside tissue. By manipulating many degrees of the incident optical wavefront, the latest optical wavefront engineering (WFE) technology compensates the wavefront distortions caused by the scattering media and thus is toward breaking this physical limit, bringing bright perspective to many applications deep inside tissue, e.g., high resolution functional/molecular imaging, optical excitation (optogenetics) and optical tweezers. However, inside the dynamic turbid media such as the biological tissue, the wavefront distortion is a fast and continuously changing process whose decorrelation rate is on timescales from milliseconds (ms) to microseconds ([Formula: see text]s), or even faster. This requires that the WFE technology should be capable of beating this rapid process. In this review, we discuss the major challenges faced by the WFE technology due to the fast decorrelation of dynamic turbid media such as living tissue when achieving light focusing/imaging and summarize the research progress achieved to date to overcome these challenges.

Tunable-liquid-crystal-filter-based low-light-level color night vision system and its image processing method.

We introduce and verify a single-channel time-division filtering low-light-level (LLL) color night vision system (3LCNV). The imaging scheme, comprising a tunable liquid crystal filter, three-generation GaAsP image intensifier, and CMOS camera, achieves LLL color imaging and ensures sensitivity. The image enhancement and color reconstruction algorithm flow suitable for LLL night vision combines overexposure-against white balance, color correction matrix (CCM) color correction, and color image denoising to improve color visibility and reduce color difference and image noise. The proposed night vision system extends the minimum working illuminance to 10-4 lx and achieves natural and clear color LLL imaging, improving night-time observations.

Prognostic imaging of iatrogenic and traumatic ureteral injury by near-infrared fluorescence.

Iatrogenic or traumatic ureteral injuries are life-threatening but difficult to diagnose early. Ureteral visualization is essential for both the prevention and diagnosis of iatrogenic or traumatic ureter injuries. In the present study, we evaluated the feasibility of near-infrared (NIR) with ZW800-1C as a diagnostic tool of iatrogenic or traumatic ureteral injury in addition to ureter visualization, compared to methylene blue. With mice model, we compared the image quality of ZW800-1C with methylene blue for ureter visualization. We also made ureter perforation, obstruction, crushing injury, and transection model with mice and evaluated the feasibility of ZW800-1C for diagnostic tool for ureteral injuries. We could confirm the ureter in the ZW800-1C images in maximally 30 minutes after injection, and the ureter was visible until NIR imaging concluded at 180 minutes after injection. However, methylene blue failed to provide clear ureter imaging during the same period. ZW800-1C imaging successfully visualized ureters subjected to obstruction, transection, perforation, and crush injuries, although urinary leakage was not visible by eye. Our results indicate ZW800-1C is better suited for ureter visualization than methylene blue and that ZW800-1C has considerable potential for the early diagnosis of various ureteral injuries.

"Yokoyama procedure" efficacy on non-highly myopic patients with acquired esotropia and hypotropia.

To assess the efficacy of "Yokoyama Procedure," on non-highly myopic patients with acquired esotropia and hypotropia. The study involved 10 eyes of 5 patients with eso-hypotropia. Inclusion criteria were acquired esotropic-hypotropic strabismus with lateral rectus inferior displacement and superior rectus nasal displacement confirmed by magnetic resonance imaging, refractive errors between ±6 D, and axial length < 27 mm. Range of full duction movements and maximum angles of abduction-sursumduction was measured in each eye before and after surgery. All patients underwent T1- and T2-weighted magnetic resonance imaging. The surgery was aimed at creating a junction between the muscle bellies of the superior and lateral rectus muscles. This junction was made approximately 14 mm behind the insertions using a non-absorbable mersilene 5/0 suture (Yokoyama procedure). Mean patient age was 64.8 ± 4.8 years. The mean globe axial length was 25.4 ± 0.76 mm and a mean corresponding spherical equivalent refraction of -3.7 ± 1.7 D was observed. Eight eyes on 10 had mild limitation in abduction, while the remaining 2 had no limitation. Three out of 10 eyes showed a moderate limited sursumduction, 5 eyes were categorized as mild, and the remaining 2 had no limitation. No evident post-operative limitation was present in any eye, in both abduction and sursumduction (p < 0.01). Pre-operative esotropia and hypotropia were, respectively, 32 ± 11 prismatic diopters and 25 ± 5 prismatic diopters, and they were significantly reduced after surgery as 9 ± 1.7 prismatic diopters and 6 ±1 prismatic diopters (p = 0.043), respectively. Yokoyama procedure is an effective, fast, reversible procedure to face eso-hypotropic acquired strabismus, even in patients with a clear magnetic resonance imaging displacement of superior and lateral rectus muscles, and absence of globe dislocation and of elevated myopia.

A triarylboron-based binuclear Zn(II) complex as a two-photon fluorescent probe for simultaneous multicolor imaging of the cell membrane, endoplasmic reticulum, and nucleolus.

The visualization of subcellular structures is critical for understanding their intracellular function. We prepared two triarylboron-based multinuclear Zn2+ complexes, TAB-1-3Zn2+ and TAB-2-2Zn2+, which can be used as fluorescent probes for nucleoside polyphosphate (NPP) and RNA because their multi Zn2+ center can selectively combine with the phosphate side chain of NPP or RNA, accompanied by a corresponding fluorescence change. Among them, TAB-2-2Zn2+ is more suitable than TAB-1-3Zn2+ for live cell imaging because of its excellent cell membrane permeability resulting from amphiphilicity. Since the various membrane structures in cells are also composed of phosphoric acid bilayers, TAB-2-2Zn2+ may also be used to image various membrane structures. Various colocalization experiments further confirmed that TAB-2-2Zn2+ can achieve clear simultaneous imaging of the cell membrane, the endoplasmic reticulum, and the nucleolus. Graphical abstract.

Three-Motorized-Stage Cyclic Stretching System for Cell Monitoring Based on Chamber Local Displacement Waveforms

Researchers have developed a cell stretching device to mimic the in vivo mechanical environment in vitro in order to investigate cell mechanotransduction. Cyclic stretch is involved in lengthening and relaxation phases. Cells may respond to mechanical stimulation rapidly within a few seconds, and sudden disruption of cell cytoskeletons may also occur at any point in any phase of cyclic stretch. However, until now, no research has been done to establish a method of collecting cell images at the two phases of cyclic stretch. Because image processing is time-consuming, it is difficult to adjust focus and collect high-resolution images simultaneously at the two phases during the process. In this study, a three-motorized-stage system was developed to meet the requirements. The results demonstrated that linear compensation is effective for cell imaging, and it is applicable to have a feed-forward control method without image processing. A method was then developed to determine the maximum displacement of the target in the horizontal and vertical directions, and the linear compensation waveforms were designed using the C program automatically and immediately before stretching. Further, the cyclic stretch was applied to cells using the three motorized stages, and clear phase-contrast cell imaging (30 fps) were obtained almost at any point in time. Detailed cell changes such as sudden disruption of cell–cell junctions, not only long-term cell response, were observed. Therefore, our study established a methodology to greatly improve the time resolution of imaging of cyclic stretch for the research of detailed cellular mechanotransduction.

New Polylactic Acid Multifunctional Ultrasound Contrast Agent Based on Graphene Oxide as the Carrier of Targeted Factor and Drug Delivery.

In recent years, the development of ultrasound contrast agents has encouraged their use as a drug system for diagnosis and therapy. In this paper, polylactic acid (PLA) composite microbubbles (FA/DOX/GO/DOX/PLA) were prepared with graphene oxide (GO) as a carrier of the targeted factor folic acid (FA) and doxorubicin (DOX) by the multiple emulsification–solvent evaporating process. Appearance, particle size, and zeta potential of PLA composite microbubbles were characterized by using a nanoparticle size analyzer and transmission electron microscopy. Breast cancer cells MCF-7 were used to evaluate the antitumor activity of PLA composite microbubbles in vitro by using the CCK-8 and acridine orange staining method. The ultrasonic imaging effect of PLA composite microbubbles was investigated in New Zealand white rabbits by the Doppler color ultrasound imaging system. With Kunming mice as the research model, the acute toxicity of PLA composite microbubbles was examined. The experimental results showed that the prepared PLA composite microbubbles presented a hollow and spherical shape with a particle size of 600 nm or so and a zeta potential of −37.5 ± 10.0 mV. They had a good effect of the enhancing imaging, and clear ultrasound imaging can be obtained. PLA composite microbubbles showed a significant proliferation inhibition effect on breast cancer cells MCF-7 in a dose-dependent manner. After PLA composite microbubbles were modified by FA, they were good for targeting FA receptors on the surface of MCF-7 cells, which increased the inhibition rate of the tumor cells. LD50 of PLA composite microbubbles was 87.529 mg·kg–1; the mice did not show the acute toxicity when the dose of composite microbubbles was lower than this value.

10-mm Laparo-Endoscopic Single-Site Cholecystectomy Using Multiple Magnetically Anchored and Controlled Instruments

BackgroundTo study the feasibility of laparo-endoscopic single-site (LESS) cholecystectomy through a 10-mm incision using a miniature magnetically anchored and controlled laparoscopy system and a grasper system. MethodsThe miniature magnetically anchored and controlled laparoscopy system consisted of a miniature magnetically anchored camera (MMAC), an external magnetic anchoring unit, and a vision output device. The camera weighed 9.8 g and measured Φ10 mm × 50 mm. The magnetically anchored and controlled grasper system consisted of a magnetically anchored grasper (MAG), an external magnetic anchoring unit, and a push–pull device. The MAG had a titanium alloy clip head and a magnetic tail. The laparoscopy system and grasper system were used simultaneously to perform LESS cholecystectomy through a single 10-mm incision in model canines. ResultsLESS cholecystectomy through a 10-mm incision using the MMAC and MAG was attempted in six dogs. The mean operative time was 85.75 ± 7.14 min. The operation was completed successfully in four cases, with failure occurring in one case due to gallbladder rupture and in another due to bile duct injury. The MMAC provided clear imaging, and the MAG provided sufficient exposure to perform the cholecystectomy. The use of multiple magnetically anchored and controlled instruments did not result in notable collisions. ConclusionsThe designed MMAC and MAG system could be easily maneuvered. LESS cholecystectomy may be feasible through a single 10-mm incision with the simultaneous use of multiple magnetically anchored and controlled instruments.

Moving shot, an affordable and high-throughput setup for direct imaging of fast-moving microdroplets

Droplet microfluidics have a great potential in chemical and biomedical applications, due to their high throughput, versatility, and massive parallelism. To enhance their throughput, many devices based on the droplet microfluidics are using a flow-through configuration, in which the droplets are generated, transported, and analyzed in a continuous stream with a high velocity. Direct imaging of moving droplets is often necessary to characterize the spatiotemporal dynamics of the chemical reaction and physical process in the droplets. However, due to the motion blur caused by the movement of the droplets during exposure, an expensive high-speed camera is required for clear imaging, which is cost prohibitive in many applications. In this paper, we are presenting ‘Moving shot’ to demonstrate direct imaging of fast-moving droplets in microfluidic channels at an affordable cost. A microfluidic device is translated at the same velocity but in the opposite direction of moving droplets in it, so that the droplets are stationary with respect to the objective lens. With this approach, we can image fluorescent droplets moving at 0.34 cm s−1 with an exposure time up to 2 s without motion blur. We strongly believe that the proposed technique can enable cost-effective and high-throughput imaging of fast-moving droplets in a microfluidic channel.

Development of an image biosensor based on an optogenetically engineered cell for visual prostheses.

Visual prostheses provide blind patients with artificial vision via electrical stimulation of surviving visual cells resulting in partial restoration of vision in many patients. However, high-resolution visual perception, long-term biocompatibility and safety remain the significant challenges of existing visual prostheses. Here, we present a novel method to develop a new visual prosthesis using living cells as integrated electronics and implantable microelectrodes. The living cells modified with channelrhodopsin-2 showed excellent light-sensitive properties and encoded image information with cellular deformations triggered by light stimulation. The photoresponsive properties of the cells were determined using a single pixel imaging system, which indicated that the cells can act as a good light-sensitive biosensor. Additionally, the imaging feasibility of the cells was further validated through successful and clear imaging of several object scenes using the same system. This work represents a step toward the design and use of living cells as an image biosensor for the development of a new generation of high-resolution visual prostheses.

Skeletal changes after rapid maxillary expansion in children with obstructive sleep apnea evaluated by low-dose multi-slice computed tomography

ObjectiveThe objective of this study was to evaluate the skeletal effects of rapid maxillary expansion (RME) therapy performed using teeth as anchors, in obstructive sleep apnea (OSA) children, by low-dose computed tomography (CT) of the midpalatal suture opening, maxillary base width, nasal cavities width, first molar angulation and, unlike most studies in the literature, on the pterygoid processes distance. MethodsFourteen children (mean age 8.68 years) with OSA presenting a malocclusion characterized by upper-jaw contraction had 16-Multislice CT (MSCT) scans taken before (T0) and after (T1) RME. All exams were performed using a rigid protocol to ensure reproducibility of image collection over time, with a 16-row MSCT scanner equipped with a Dentascan reconstruction program. Scanning parameters were as follows: scout view in the anteroposterior (AP) and laterolateral (LL); 1.25-mm slice thickness with 0.6-mm collimation from the dentoalveolar and basal areas of the maxilla up to the nasal cavity, parallel to the palatal plane; 80 kV, 100 mA with an 11.25-mm table speed/rotation, rotation time 0.6 s. Matrix size was 512 × 512. ResultsOpening of the midpalatal suture was demonstrated in all cases. The results showed statistically significant T0 to T1 increments in all treated cases and clear imaging findings. ConclusionUse of three-dimensional (3D)-CT for follow-up studies requires a very rigid protocol to maintain reproducible positions in the scanner over time. The images confirm the real remodeling of craniofacial structure. However, to be valid such an imaging approach needs great attention to reproducibility of anatomic images over time. The changes in volume of the UA, even with a rigid protocol, cannot be affirmed with 3D-CT. There is a need to improve the definition of markers using this imaging approach when performing longitudinal studies; currently this issue is unresolved.

Homologous Gold Nanoparticles and Nanoclusters Composites with Enhanced Surface Raman Scattering and Metal Fluorescence for Cancer Imaging.

A large number of deaths from cancer can be attributed to the lack of effective early-stage diagnostic techniques. Thus, accurate and effective early diagnosis is a major research goal worldwide. With the unique phenomenon of localized surface plasmon resonance (LSPR), plasmonic nanomaterials have attracted considerable attention for applications in surface-enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF). Both SERS and MEF are ultra-sensitive methods for the detection and identification of early tumor at molecular level. To combine the merits of the fast and accurate imaging of MEF and the stable and clear imaging of SERS, we propose a novel dual functional imaging nanoprobe based on gold nanoparticles and gold nanocluster composites (denoted AuNPC-RGD). The gold nanoparticles are used as LSPR substrates to realized enhancement of Raman or fluorescence signal, while the gold nanoclusters serve as a fluorophore for MEF imaging, and exhibit better biocompatibility and stability. Furthermore, target molecule of cyclic Arg-Gly-Asp (cRGD) is incorporated into the composite to improve delivery efficiency, selectivity and imaging accuracy. These integrated properties endow AuNPC-RGD composites with outstanding biocompatibility and excellent imaging abilities, which could be used to achieve accurate and effective diagnosis for early cancer.