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2.
Neuroscience ; 545: 158-170, 2024 May 03.
Article En | MEDLINE | ID: mdl-38513765

Thioredoxin-reductase 2 (Txnrd2) belongs to the thioredoxin-reductase family of selenoproteins and is a key antioxidant enzyme in mammalian cells to regulate redox homeostasis. Here, we reported that Txnrd2 exerted a major influence in brain damage caused by Intracerebral hemorrhage (ICH) by suppressing endoplasmic reticulum (ER) stress oxidative stress and via Trx2/Prx3 pathway. Furthermore, we demonstrated that pharmacological selenium (Se) rescued the brain damage after ICH by enhancing Txnrd2 expression. Primarily, expression and localization of Txnrd2, Trx2 and Prx3 were determined in collagenase IV-induced ICH model. Txnrd2 was then knocked down using siRNA interference in rats which were found to develop more severe encephaledema and neurological deficits. Mechanistically, we observed that loss of Txnrd2 leads to increased lipid peroxidation levels and ER stress protein expression in neurons and astrocytes. Additionally, it was revealed that Se effectively restored the expression of Txnrd2 in brain and inhibited both the activity of ER stress protein activity and the generation of reactive oxygen species (ROS) by promoting Trx2/Prx3 kilter when administrating sodium selenite in lateral ventricle. This study shed light on the effect of Txnrd2 in regulating oxidative stress and ER stress via Trx2/Prx3 pathway upon ICH and its promising potential as an ICH therapeutic target.


Cerebral Hemorrhage , Endoplasmic Reticulum Stress , Oxidative Stress , Rats, Sprague-Dawley , Thioredoxin Reductase 2 , Thioredoxins , Animals , Male , Rats , Astrocytes/metabolism , Astrocytes/drug effects , Brain/metabolism , Brain/drug effects , Brain/pathology , Brain Injuries/metabolism , Cerebral Hemorrhage/metabolism , Cerebral Hemorrhage/pathology , Disease Models, Animal , Endoplasmic Reticulum Stress/physiology , Endoplasmic Reticulum Stress/drug effects , Neurons/metabolism , Neurons/drug effects , Neurons/pathology , Oxidative Stress/drug effects , Oxidative Stress/physiology , Peroxiredoxin III/metabolism , Reactive Oxygen Species/metabolism , Selenium/pharmacology , Signal Transduction/physiology , Signal Transduction/drug effects , Thioredoxin Reductase 2/metabolism , Thioredoxins/metabolism
3.
Anal Chem ; 96(4): 1436-1443, 2024 01 30.
Article En | MEDLINE | ID: mdl-38173081

We report a dual-signal chemical exchange saturation transfer (Dusi-CEST) strategy for drug delivery and detection in living cells. The two signals can be detected by operators in complex environments. This strategy is demonstrated on a cucurbit[6]uril (CB[6]) nanoparticle probe, as an example. The CB[6] probe is equipped with two kinds of hydrophobic cavities: one is found inside CB[6] itself, whereas the other exists inside the nanoparticle. When the probe is dispersed in aqueous solution as part of a hyperpolarized 129Xe NMR experiment, two signals appear at two different chemical shifts (100 and 200 ppm). These two resonances correspond to the NMR signals of 129Xe in the two different cavities. Upon loading with hydrophobic drugs, such as paclitaxel, for intracellular drug delivery, the two resonances undergo significant changes upon drug loading and cargo release, giving rise to a metric enabling the assessment of drug delivery success. The simultaneous change of Dusi-CEST likes a mobile phone that can receive both LTE and Wi-Fi signals, which can help reduce the occurrence of false positives and false negatives in complex biological environments and help improve the accuracy and sensitivity of single-shot detection.


Magnetic Resonance Imaging , Water , Magnetic Resonance Spectroscopy , Hydrophobic and Hydrophilic Interactions
4.
Nat Commun ; 14(1): 8130, 2023 Dec 08.
Article En | MEDLINE | ID: mdl-38065957

The presence of a static tilt between the inner core and mantle is an ongoing discussion encompassing the geodynamic state of the inner core. Here, we confirm an approximate 8.5 yr signal in polar motion is the inner core wobble (ICW), and find that the ICW is also contained in the length-of-day variations of the Earth's rotation. Based on the determined amplitudes of the ICW and its good phase consistency in both polar motion and the length-of-day variations, we infer that there must be a static tilt angle θ between the inner core and the mantle of about 0.17 ± 0.03°, most likely towards ~90°W relative to the mantle, which is two orders of magnitude lower than the 10° assumed in certain geodynamic research. This tilt is consistent with the assumption that the average density in the northwestern hemisphere of the inner core should be greater than that in the other regions. Further, the observed ICW period (8.5 ± 0.2 yr) suggests a 0.52 ± 0.05 g/cm3 density jump at the inner core boundary.

5.
Cancer Med ; 12(18): 18491-18502, 2023 Sep.
Article En | MEDLINE | ID: mdl-37564011

BACKGROUND: Real-world evidence on immune-related adverse events (irAEs) are relatively insufficient. Herein patterns and outcomes of irAEs after administration of anti-programmed cell death 1 (PD-1) and its legend 1 (PD-L1) antibodies were investigated. METHODS: Patients treated with anti-PD-1/PD-L1 drugs from January 2018 to September 2021 at Huadong Hospital, Fudan University were included. Common Terminology Criteria for Adverse Events (CTCAE) was used for irAEs evaluation. The primary endpoints were the clinical description of irAEs. RESULTS: Two hundred and forty-one solid tumor patients were included, with lung cancer as the most common tumor type (56%). 187 (77.6%) patients presented any kind of irAEs. The median time to any irAE onset was 28 (95% CI 24-32) days. Skin toxicities are the most common irAEs (46.1%) and the irAEs (36.5%) occurred earliest after immune-checkpoint inhibitors. The most frequently occurred all-grade irAEs were rash (23.7%), myelosuppression (20.7%), and hepatic injury (19.5%). 23 (9.5%) patients died of severe irAEs, which consists of 10 patients with pneumonitis, four colitis, four myocarditis, and one each for gastritis, pulmonary embolism, myelosuppression, hypophysitis, and encephalitis. Patients with any irAE onset had significantly longer progression-free survival (PFS) (p = 0.013) and overall survival (OS) (p = 0.007), respectively, than patients without irAEs. In addition, patients with skin toxicities (p = 0.012) or blood toxicities (p = 0.015) had achieved a longer PFS, than those without corresponding toxitities, respectively. CONCLUSION: Most irAEs are mild and manageable, while some irAEs can present at later time or can be life-threatening, especially pneumonitis as we observed. Patients with any irAE onset may achieve a better prognosis than those without irAEs, and presentation of skin or blood toxicities will indicate a better PFS.

6.
Microbes Infect ; 25(5): 105098, 2023 06.
Article En | MEDLINE | ID: mdl-36621527

Three Orientia tsutsugamushi genotypic groups belonging to two prototypes (Gilliam and Karp) were identified in scrub typhus patients from Guangxi, Southwest China. Fever, headache, pneumonia, fatigue, chill, and anorexia were the most common clinical signs. Frequent recombination was observed for their 47-kDa gene compared to 56-kDa and 16S genes. Furthermore, patients infected with the Gilliam prototype represent a much higher proportion of pneumonia (6/6, 100%) than those infected with the Karp prototype (4/8, 50%) (p-value = 0.040). This discrepancy is consistent with recent animal tests on rhesus and may indicate different virulence and tissue tropism between different O. tsutsugamushi prototypes.


Orientia tsutsugamushi , Scrub Typhus , Animals , Orientia tsutsugamushi/genetics , Scrub Typhus/epidemiology , China/epidemiology , Genotype , Recombination, Genetic
7.
Sci China Chem ; 66(2): 324-366, 2023.
Article En | MEDLINE | ID: mdl-36536633

Analyzing the complex structures and functions of brain is the key issue to understanding the physiological and pathological processes. Although neuronal morphology and local distribution of neurons/blood vessels in the brain have been known, the subcellular structures of cells remain challenging, especially in the live brain. In addition, the complicated brain functions involve numerous functional molecules, but the concentrations, distributions and interactions of these molecules in the brain are still poorly understood. In this review, frontier techniques available for multiscale structure imaging from organelles to the whole brain are first overviewed, including magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET), serial-section electron microscopy (ssEM), light microscopy (LM) and synchrotron-based X-ray microscopy (XRM). Specially, XRM for three-dimensional (3D) imaging of large-scale brain tissue with high resolution and fast imaging speed is highlighted. Additionally, the development of elegant methods for acquisition of brain functions from electrical/chemical signals in the brain is outlined. In particular, the new electrophysiology technologies for neural recordings at the single-neuron level and in the brain are also summarized. We also focus on the construction of electrochemical probes based on dual-recognition strategy and surface/interface chemistry for determination of chemical species in the brain with high selectivity and long-term stability, as well as electrochemophysiological microarray for simultaneously recording of electrochemical and electrophysiological signals in the brain. Moreover, the recent development of brain MRI probes with high contrast-to-noise ratio (CNR) and sensitivity based on hyperpolarized techniques and multi-nuclear chemistry is introduced. Furthermore, multiple optical probes and instruments, especially the optophysiological Raman probes and fiber Raman photometry, for imaging and biosensing in live brain are emphasized. Finally, a brief perspective on existing challenges and further research development is provided.

8.
STAR Protoc ; 3(3): 101499, 2022 09 16.
Article En | MEDLINE | ID: mdl-35776640

Due to limited detection sensitivity and contrast limitation, imaging substrates with 129Xe MRI in living cells is still a challenge. Here, we present an effective protocol to detect and image substrates in human lung cancer cells A549 with hyperpolarized 129Xe MRI. This protocol was optimized for a cryptophane-based probe sensitive to biothiols and can be expanded to other Xe-based probes to detect potential biomarkers in other mammalian cells. For complete details on the use and execution of this protocol, please refer to Zeng et al. (2021).


Lung Neoplasms , Xenon Isotopes , Animals , Humans , Lung Neoplasms/diagnostic imaging , Magnetic Resonance Imaging/methods , Mammals , Molecular Probes , Xenon Isotopes/chemistry
9.
Front Aging Neurosci ; 14: 816443, 2022.
Article En | MEDLINE | ID: mdl-35493926

Objective: To evaluate the longitudinal association of nut consumption with cognitive function in Chinese elderly. Methods: We analyzed the data from Zhejiang Ageing and Health Cohort Study including 9,028 participants. Nut consumption was evaluated in baseline questionnaire beginning at 2014. Cognitive function was assessed repeatedly through the Mini-Mental State Examination (MMSE) at baseline and three waves of follow-up (2015, 2016, and 2019-2020). Cognitive impairment was defined using education-specific cut-off points. Log-binomial regression models with the generalized estimating equations, controlled for an extensive range of potential confounders, were utilized to evaluate the association and estimate relative risk (RR). Results: After 6 years of follow-up, 3,266 (36.18%) participants were indicated as cognitive impairment by MMSE at least once. Compared with non-consumers or less-than-weekly consumers, participants consuming ≥70 g/week of nuts had 17% lower risks of cognitive impairment (RR = 0.83, 95% CI 0.75-0.91), whereas no association was found in those consuming <70 g/week of nuts. Moreover, relatively infrequent higher-amount consuming (≥70 g within one consuming day each week) was not associated with better cognitive performance. Furthermore, we did not observe significant effect modification caused by frequency of other food intake. Conclusion: Higher nut consumption was prospectively related to a lower risk of cognitive impairment in Chinese elderly.

10.
Bioengineered ; 13(4): 9959-9972, 2022 04.
Article En | MEDLINE | ID: mdl-35416122

The recurrence and metastasis of gastric cancer are related to the stemness of gastric cancer cells. Researches have shown that miR-18 level is negatively correlated to the occurrence and development of certain cancer types. However, the effects of miR-18 on the stemness of gastric cancer remain uncertain. In this research, gastric cancer cell lines with stable overexpression of miR-18 were constructed through lentivirus infection. CCK-8 assay, RT-qPCR, Western blot, flow cytometry, and in vivo tumorigenesis assays were performed to evaluate the effects of miR-18 on the stemness of gastric cancer cells. Moreover, luciferase reporter assays found that Meis2 was the target of miR-18. Furthermore, we also found that the low-expressed oncogene HMGB3 is involved in this miR-18/Meis2 axis to further promote the stemness of gastric cancer cells. These findings suggest that the miR-18/Meis2/HMGB3 axis may be potential prognostic indicators for patients with gastric cancer.


HMGB3 Protein , MicroRNAs , Stomach Neoplasms , Cell Line, Tumor , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , HMGB3 Protein/genetics , HMGB3 Protein/metabolism , Homeodomain Proteins/metabolism , Humans , MicroRNAs/genetics , MicroRNAs/metabolism , Oncogenes , Stomach Neoplasms/genetics , Stomach Neoplasms/pathology , Transcription Factors/metabolism
11.
Int J Colorectal Dis ; 37(5): 1097-1106, 2022 May.
Article En | MEDLINE | ID: mdl-35419711

OBJECTIVE: The aim of this study was to investigate the prognostic value of baseline peripheral blood neutrophils, monocytes, and lymphocytes on locally advanced rectal cancer (LARC) patients. METHODS: Clinicopathologic data of 317 LARC patients during July 2010 and October 2016 were retrospectively gathered. X-tile software was used to acquire the optimal cutoff values of neutrophils, monocytes, and lymphocytes. Peripheral blood immune score (PBIS) system was proposed and built based on neutrophils, monocytes, and lymphocytes. The Cox model was used to analyze the associations between clinicopathological characteristics and potential outcomes. C-index was used to assess model performance. A nomogram was constructed to predict prognosis, and a calibration plot was used to verify the accuracy of the nomogram prediction model. RESULTS: Cutoff values of neutrophils, lymphocytes, and monocytes were 4.46 (× 109/L), 1.66 (× 109/L), and 0.39 (× 109/L), respectively. PBIS was related to sex (P < 0.001), tumor length (P = 0.003), and tumor thickness (P = 0.014). Multivariate Cox regression analysis revealed that PBIS (HR = 0.707, 95% CI: 0.549-0.912, P = 0.008) was an independent predictor of DFS. High PBIS (HR = 0.697, 95% CI: 0.492-0.988, P = 0.043) and high lymphocyte count (HR = 0.511, 95%CI: 0.273-0.958, P = 0.036) were favorable factors of OS. Both C-index (0.74, 95% CI: 0.549-0.912) and the calibration plot showed good prediction ability of the nomogram for DFS. CONCLUSION: PBIS, composed of baseline peripheral blood neutrophils, monocytes, and lymphocytes, is an independent predictor of the prognosis of LARC. Combination of PBIS and ypTNM stage may be a promising marker to guide adjuvant therapy after the operation.


Neutrophils , Rectal Neoplasms , Humans , Lymphocytes/pathology , Monocytes/pathology , Neoadjuvant Therapy , Neutrophils/pathology , Prognosis , Rectal Neoplasms/pathology , Retrospective Studies
12.
BMC Pulm Med ; 21(1): 318, 2021 Oct 12.
Article En | MEDLINE | ID: mdl-34641843

BACKGROUND: Innate lymphoid cells (ILCs), as an important group of innate immunity, could respond rapidly to Mycobacterium tuberculosis (Mtb) infection. In this research, we studied the phenotypic changes of circulatory ILCs in active tuberculosis (TB) disease. METHODS: We recruited 40 patients with active Mtb infection (TB group) and 41 healthy subjects (NC group), and collected their clinical information and peripheral blood. Circulating ILCs, ILC subsets, dendritic cells (DCs), macrophages, and the production of cytokines in ILCs were tested by flow cytometry (FCM). Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma IL-23. RESULTS: Compared with healthy control, total ILCs (0.73% vs. 0.42%, P = 0.0019), ILC1 (0.55% vs. 0.31%, P = 0.0024) and CD117+ ILC2 (0.02% vs. 0.01%, P = 0.0267) were upregulated in TB group. The total IL-17+ lymphocytes were elevated (3.83% vs. 1.76%, P = 0.0006) while the IL-22+ lymphocytes remained unchanged. Within ILC subsets, ILC3, CD117+ ILC2 and ILC1 in TB group all expressed increased IL-17 (15.15% vs. 4.55%, 19.01% vs. 4.57%, 8.79% vs. 3.87%, P < 0.0001) but similar IL-22 comparing with healthy control. TB group had more plasma IL-23 than NC group (7.551 vs. 5.564 pg/mL, P = 0.0557). Plasma IL-23 in TB group was positively correlated to IL-17+ ILC3 (r = 0.4435, P = 0.0141), IL-17+CD117+ ILC2 (r = 0.5385, P = 0.0021) and IL-17+ ILC1(r = 0.3719, P = 0.0430). TB group also had elevated DCs (9.35% vs. 6.49%, P < 0.0001) while macrophages remained unchanged. Within TB group, higher proportion of IL-17+ ILCs was related to severer inflammatory status and poorer clinical condition. CONCLUSIONS: In active TB disease, circulatory ILCs were upregulated and exhibited IL-17-expressing phenotype. This may expand the understanding of immune reaction to Mtb infection.


Immunity, Innate , Interleukin-17/metabolism , Lymphocytes/immunology , Tuberculosis/immunology , Adult , Aged , Case-Control Studies , Female , Flow Cytometry , Humans , Lymphocytes/metabolism , Male , Middle Aged , Mycobacterium tuberculosis , Phenotype , Tuberculosis/metabolism
13.
J Phys Chem Lett ; 12(35): 8652-8657, 2021 Sep 09.
Article En | MEDLINE | ID: mdl-34472873

Functionalized hyperpolarized xenon "cage" molecules have often been used for ultrasensitive detection of biomolecules and microenvironment properties. However, the rapid and accurate measurement of molecule concentration is still a challenge. Here, we report a molecule concentration measurement method using long-interval chemical exchange inversion transfer (CEIT) NMR spectroscopy. The molecule concentration can be quantitatively measured with only 2 scans, which shortens the acquisition time by about 10 times compared to conventional Hyper-CEST (chemical exchange saturation transfer) z-spectrum method. Moreover, we found that the accuracy of concentration determination would be the best when the CEIT effect is 1-1/e or close to it, and a relative deviation of CrA-(COOH)6 less than ±1% has been achieved by only a one-step optimization of the number of cycles. The proposed method enables efficient and accurate determination of molecule concentration, which provides a potential way for rapid quantitative molecular imaging applications.

14.
Chem Sci ; 12(12): 4300-4308, 2021 Feb 09.
Article En | MEDLINE | ID: mdl-34163694

As one of the most important imaging modalities, magnetic resonance imaging (MRI) still faces relatively low sensitivity to monitor low-abundance molecules. A newly developed technology, hyperpolarized 129Xe magnetic resonance imaging (MRI), can boost the signal sensitivity to over 10 000-fold compared with that under conventional MRI conditions, and this technique is referred to as ultrasensitive MRI. However, there are few methods to visualize complex mixtures in this field due to the difficulty in achieving favorable "cages" to capture the signal source, namely, 129Xe atoms. Here, we proposed metal-organic frameworks (MOFs) as tunable nanoporous hosts to provide suitable cavities for xenon. Due to the widely dispersed spectroscopic signals, 129Xe in different MOFs was easily visualized by assigning each chemical shift to a specific color. The results illustrated that the pore size determined the exchange rate, and the geometric structure and elemental composition influenced the local charge experienced by xenon. We confirmed that a complex mixture was first differentiated by specific colors in ultrasensitive MRI. The introduction of MOFs helps to overcome long-standing obstacles in ultrasensitive, multiplexed MRI.

16.
Nat Commun ; 12(1): 1215, 2021 02 22.
Article En | MEDLINE | ID: mdl-33619266

The near-surface part of the crust, also called the skin of the earth, is the arena of human activity of which the stiffness is of great concern to engineers in infrastructure construction. The stiffness reduction of near-surface geomaterials also plays a vital role in geohazards triggering. However, the physical mechanism behind the material softening is still not fully understood. Here, we report a coseismic shear-wave velocity reduction in the near surface by up to a few tens of percent during the strongest shaking from the 11 March 2011 Tohoku-Oki Earthquake and a subsequent two-stage healing process including a rapid recovery within a few minutes and a slow recovery over many years. We also present a theoretical contact model between mineral grains in geomaterials containing multiple metastable contacts at small separations due to the oscillatory hydration interaction, which can explain the emergence of different stages in the healing process.

17.
Front Cell Neurosci ; 14: 578060, 2020.
Article En | MEDLINE | ID: mdl-33281556

Intracerebral hemorrhage (ICH) is a common and severe neurological disorder that can effectively induce oxidative stress responses. NADPH oxidase 4 (NOX4) is a member of the NOX family of oxidases. It is expressed in the brain normally and involved in cell signal transduction and the removal of harmful substances. In some pathological conditions, it mediates inflammation and the aging of cells. However, few studies have focused on whether NOX4 is involved in brain injury caused by ICH. Therefore, this study aimed to clarify the role of NOX4 in the pathological process that occurs after ICH and the potential mechanism underlying its role. A rat model of ICH was established by the injection of collagenase type IV, and the expression of NOX4 was then determined. Further, siRNA-mediated protein expression knockdown technology was used for NOX4 knockdown, and western immunoblotting, immunohistochemistry, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and other molecular biological techniques were performed to assess the effects of NOX4 knockdown. Neurobiological scoring, brain water content determination, and other brain injury detection methods were also performed to assess the role of NOX4 following ICH. We found that the expression of NOX4 increased in the brains of rats after ICH, and that it was mainly expressed in neurons, astrocytes, vascular endothelial cells and microglia. Following NOX4 knockdown, the level of oxidative stress in the brain decreased considerably, the neurobehavioral scores improved, the levels of neuronal apoptosis reduced markedly, and the impairment of blood-brain barrier function was significantly ameliorated in rats with ICH. In conclusion, this study suggests that NOX4 expression is upregulated after ICH, which may cause an imbalance in the oxidative stress of relevant cells in the brain, leading to subsequent apoptosis of neurons and damage to the blood-brain barrier due to secondary brain injury following ICH.

18.
ACS Appl Mater Interfaces ; 12(51): 57290-57301, 2020 Dec 23.
Article En | MEDLINE | ID: mdl-33231083

Our exploration of multimodal nanoprobes aims to combine photoacoustic (PA) imaging, 19F magnetic resonance (MR), and fluorescence (FL) imaging, which offers complementary advantages such as high spatial resolution, unlimited penetration, and high sensitivity to enable more refined images for accurate tumor diagnoses. In this research, perfluorocarbons (PFCs) and indocyanine green (ICG) are encapsulated by poly(lactic-co-glycolic acid) (PLGA) for intravital 19F MR/FL/PA tri-modal imaging-guided photothermal therapy. Then, it is coated with an A549 cancer cell membrane (AM) to fabricate versatile theranostic nanoprobes (AM-PP@ICGNPs). After systemic administration, FLI reveals time-dependent tumor homing of NPs with high sensitivity, 19F MRI provides tumor localization of NPs without background signal interference, and PAI illustrates the detailed distribution of NPs inside the tumor with high spatial resolution. What is more, AM-PP@ICGNPs accumulated in the tumor area exhibit a prominent photothermal effect (48.4 °C) under near infrared (NIR) laser irradiation and realize an enhanced antitumor response in vivo. These benefits, in combination with the excellent biocompatibility, make AM-PP@ICGNPs a potential theranostic nanoagent for accurate tumor localization and ultimately achieve superior cancer therapy.


Antineoplastic Agents/therapeutic use , Cell Membrane/chemistry , Nanoparticles/therapeutic use , Neoplasms/drug therapy , A549 Cells , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/radiation effects , Fluorine/chemistry , Fluorocarbons/chemistry , Fluorocarbons/radiation effects , Fluorocarbons/therapeutic use , Humans , Indocyanine Green/chemistry , Indocyanine Green/radiation effects , Indocyanine Green/therapeutic use , Infrared Rays , Magnetic Resonance Imaging , Male , Mice, Inbred BALB C , Nanoparticles/chemistry , Nanoparticles/radiation effects , Neoplasms/diagnostic imaging , Optical Imaging , Photoacoustic Techniques , Photothermal Therapy/methods , Polylactic Acid-Polyglycolic Acid Copolymer/chemistry , Polylactic Acid-Polyglycolic Acid Copolymer/radiation effects , Polylactic Acid-Polyglycolic Acid Copolymer/therapeutic use , Theranostic Nanomedicine/methods , Xenograft Model Antitumor Assays
19.
Chem Commun (Camb) ; 56(92): 14427-14430, 2020 Nov 19.
Article En | MEDLINE | ID: mdl-33146184

A new non-encapsulated fluorinated liposome (TSL) was developed, which showed instantaneous temperature-induced 19F MR signal enhancement and excellent stability under reversible signal transition at different conditions.


Liposomes/chemistry , A549 Cells , Feedback , Fluorine-19 Magnetic Resonance Imaging , Halogenation , Humans , Magnesium/chemistry , Magnetic Resonance Imaging , Optical Imaging , Temperature
20.
Sensors (Basel) ; 20(8)2020 Apr 17.
Article En | MEDLINE | ID: mdl-32316478

Removal of the common mode error (CME) is very important for the investigation of global navigation satellite systems' (GNSS) error and the estimation of an accurate GNSS velocity field for geodynamic applications. The commonly used spatiotemporal filtering methods normally process the evenly spaced time series without missing data. In this article, we present the variational Bayesian principal component analysis (VBPCA) to estimate and extract CME from the incomplete GNSS position time series. The VBPCA method can naturally handle missing data in the Bayesian framework and utilizes the variational expectation-maximization iterative algorithm to search each principal subspace. Moreover, it could automatically select the optimal number of principal components for data reconstruction and avoid the overfitting problem. To evaluate the performance of the VBPCA algorithm for extracting CME, 44 continuous GNSS stations located in Southern California were selected. Compared to previous approaches, VBPCA could achieve better performance with lower CME relative errors when more missing data exists. Since the first principal component (PC) extracted by VBPCA is remarkably larger than the other components, and its corresponding spatial response presents nearly uniform distribution, we only use the first PC and its eigenvector to reconstruct the CME for each station. After filtering out CME, the interstation correlation coefficients are significantly reduced from 0.43, 0.46, and 0.38 to 0.11, 0.10, and 0.08, for the north, east, and up (NEU) components, respectively. The root mean square (RMS) values of the residual time series and the colored noise amplitudes for the NEU components are also greatly suppressed, with average reductions of 27.11%, 28.15%, and 23.28% for the former, and 49.90%, 54.56%, and 49.75% for the latter. Moreover, the velocity estimates are more reliable and precise after removing CME, with average uncertainty reductions of 51.95%, 57.31%, and 49.92% for the NEU components, respectively. All these results indicate that the VBPCA method is an alternative and efficient way to extract CME from regional GNSS position time series in the presence of missing data. Further work is still required to consider the effect of formal errors on the CME extraction during the VBPCA implementation.

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