A clinical-stage Nrf2 activator suppresses osteoclast differentiation via the iron-ornithine axis.

Activating Nrf2 by small molecules is a promising strategy to treat postmenopausal osteoporosis. However, there is currently no Nrf2 activator approved for treating chronic diseases, and the downstream mechanism underlying the regulation of Nrf2 on osteoclast differentiation remains unclear. Here, we found that bitopertin, a clinical-stage glycine uptake inhibitor, suppresses osteoclast differentiation and ameliorates ovariectomy-induced bone loss by activating Nrf2. Mechanistically, bitopertin interacts with the Keap1 Kelch domain and decreases Keap1-Nrf2 binding, leading to reduced Nrf2 ubiquitination and degradation. Bitopertin is associated with less adverse events than clinically approved Nrf2 activators in both mice and human subjects. Furthermore, Nrf2 transcriptionally activates ferroportin-coding gene Slc40a1 to reduce intracellular iron levels in osteoclasts. Loss of Nrf2 or iron supplementation upregulates ornithine-metabolizing enzyme Odc1, which decreases ornithine levels and thereby promotes osteoclast differentiation. Collectively, our findings identify a novel clinical-stage Nrf2 activator and propose a novel Nrf2-iron-ornithine metabolic axis in osteoclasts.

Impaired TFEB-mediated autophagy-lysosome fusion promotes tubular cell cycle G2/M arrest and renal fibrosis by suppressing ATP6V0C expression and interacting with SNAREs.

Increasing evidence suggests that autophagy plays a major role during renal fibrosis. Transcription factor EB (TFEB) is a critical regulator of autophagy- and lysosome-related gene transcription. However, the pathophysiological roles of TFEB in renal fibrosis and fine-tuned mechanisms by which TFEB regulates fibrosis remain largely unknown. Here, we found that TFEB was downregulated in unilateral ureteral obstruction (UUO)-induced human and mouse fibrotic kidneys, and kidney-specific TFEB overexpression using recombinant AAV serotype 9 (rAAV9)-TFEB in UUO mice alleviated renal fibrosis pathogenesis. Mechanically, we found that TFEB's prevention of extracellular matrix (ECM) deposition depended on autophagic flux integrity and its subsequent blockade of G2/M arrest in tubular cells, rather than the autophagosome synthesis. In addition, we together RNA-seq with CUT&Tag analysis to determine the TFEB targeted gene ATP6V0C, and revealed that TFEB was directly bound to the ATP6V0C promoter only at specific site to promote its expression through CUT&Run-qPCR and luciferase reporter assay. Interestingly, TFEB induced autophagic flux integrity, mainly dependent on scaffold protein ATP6V0C-mediated autophagosome-lysosome fusion by bridging with STX17 and VAMP8 (major SNARE complex) by co-immunoprecipitation analysis, rather than its mediated lysosomal acidification and degradation function. Moreover, we further investigated the underlying mechanism behind the low expression of TEFB in UUO-induced renal fibrosis, and clearly revealed that TFEB suppression in fibrotic kidney was due to DNMT3a-associated TFEB promoter hypermethylation by utilizing methylation specific PCR (MSP) and bisulfite-sequencing PCR (BSP), which could be effectively recovered by 5-Aza-2'-deoxycytidine (5A-za) to alleviate renal fibrosis pathogenesis. These findings reveal for the first time that impaired TFEB-mediated autophagosome-lysosome fusion disorder, tubular cell G2/M arrest and renal fibrosis appear to be sequentially linked in UUO-induced renal fibrosis and suggest that DNMT3a/TFEB/ATP6V0C may serve as potential therapeutic targets to prevent renal fibrosis.

Higher risk of osteoporosis in adult-onset asthma than childhood-onset asthma: from genetic and prospective evidence.

Both COA and AOA have a genetically causal effect on osteoporosis. COA and AOA were independently associated with incident osteoporosis, and the risk was greatly higher in AOA. Besides corticosteroids, the increased risk of osteoporosis among asthma patients should be attributed to genetic susceptibility and other asthma medications. PURPOSE/INTRODUCTION: Childhood-onset asthma (COA) differs with adult-onset asthma (AOA) on genetic susceptibility, severity, and co-morbidities. Whether COA or AOA is independently associated with osteoporosis is unexplored. We aimed to determine the effects of COA and AOA on osteoporosis at genetic and individual level. METHODS: We used two-sample Mendelian randomization analysis to explore the causal effects of COA and AOA on osteoporosis. In the UK Biobank cohort, we included 478,289 osteoporosis-free participants at baseline (2006-2010). Participants were classified as non-asthma, COA, and AOA at recruitment. Multivariate Cox regression analysis was used to evaluate the effects of COA, AOA, and multiple asthma medications on incident osteoporosis risk. RESULTS: COA and AOA were causally related to osteoporosis, with odds ratio of 1.007 (95% confidence interval (CI), 1.0003-1.0132) and 1.012 (95% CI, 1.002-1.023), respectively. Multivariate Cox regression analysis suggested that COA (hazard ratio (HR), 1.46; 95% CI, 1.32-1.61) and AOA (HR, 1.70; 95% CI, 1.61-1.80) were independently associated with incident osteoporosis, and the risk was greatly higher in AOA (HR, 1.51; 95% CI, 1.34-1.70). In addition to corticosteroids, monotherapy with leukotriene modifiers (HR, 1.70; 95% CI, 1.20-2.42), long-acting beta agonists (HR, 1.49; 95% CI, 1.18-1.87), and short-acting beta agonists (HR, 1.72; 95% CI1.01-2.93) were independently associated with a higher risk of osteoporosis. CONCLUSIONS: Both COA and AOA have a genetically causal effect on osteoporosis, and the risk of osteoporosis is greatly higher in AOA. Besides corticosteroids, the increased risk of osteoporosis among asthma patients should be attributed to genetic susceptibility and other asthma medications.

A Multilayer Nanofibrous Mat for the Topical Chemotherapy of the Positive Margin in Bladder Cancer.

Treatment of positive margins after solid tumor resection remains a significant challenge for clinicians. Owing to unique structural features, electrospun nanofibrous mats are promised to be an implantable antitumor system through the delivery of active agents in a controlled manner. In this study, we utilized sequential electrospinning to fabricate a multilayer mat in which gemcitabine (GEM) and cisplatin (CDDP) were electrospun individually in distinct layers. By designing the structure, the multilayer mat could deliver antitumor agents sustainedly and prolong the release of GEM, which is loaded in the inner layer. In vitro assays show that the multilayer mats effectively inhibit bladder cancer (BC) cells and elevate apoptosis. In animal models of BC, the implantable drug-loaded fibrous mat can effectively treat positive margins and prevent local recurrence. Moreover, the local delivery of GEM and CDDP significantly lowers liver toxicity compared with systemic chemotherapy. In summary, a multilayer nanofibrous mat is developed for the localized and controlled delivery of GEM, dramatically improving the treatment of residual tumors and preventing BC recurrence. Impact statement The designed multilayer nanofibrous mats can achieve two chemotherapeutic drugs (gemcitabine and cisplatin) co-loading and time-programmed sustained release, significantly improving our previous study. The antitumor effect of the drug-loaded mat in vivo and in vitro was sufficiently demonstrated. We expect to bring a new strategy of topical chemotherapy for treating positive surgical margins in bladder cancer.

Technical Note: Optimization of quantitative susceptibility mapping by streaking artifact detection.

PURPOSE: In quantitative susceptibility mapping (QSM) using magnetic resonance imaging, image reconstruction methods usually aim at suppressing streaking artifacts. In this study, a streaking detection method is proposed for evaluating and optimizing quantitative susceptibility maps. METHODS: Nine healthy subjects participated in this study and underwent three-dimensional multi-echo gradient echo scans. Regularized iterative algorithm was used for reconstruction of tissue susceptibility maps in all subjects. Streaking detection was applied to evaluate streaking artifact in tissue susceptibility maps. In addition, an optimization process for QSM reconstruction by streaking detection was applied and was compared with matching noise level method. RESULTS: It is shown that the proposed streaking detection technique effectively delineates streaking artifact in tissue susceptibility maps. In QSM reconstruction, optimization by streaking detection successfully determines the regularization factor that balances between streaking artifact suppression and tissue texture preservation. ROI analyses of brain tissue susceptibility show that optimization by streaking detection achieves results in good agreement with that from matching noise level method. CONCLUSIONS: Streaking detection enables direct visualization of streaking patterns in tissue susceptibility maps. It can be applied both for evaluating QSM reconstruction quality and for comparing different reconstruction algorithms. Furthermore, streaking detection can be incorporated into an optimization process of QSM reconstruction. Therefore, we conclude that the proposed method will add value to reconstruction of QSM.

An Augmented Reality System Using Improved-Iterative Closest Point Algorithm for On-Patient Medical Image Visualization.

In many surgery assistance systems, cumbersome equipment or complicated algorithms are often introduced to build the whole system. To build a system without cumbersome equipment or complicated algorithms, and to provide physicians the ability to observe the location of the lesion in the course of surgery, an augmented reality approach using an improved alignment method to image-guided surgery (IGS) is proposed. The system uses RGB-Depth sensor in conjunction with the Point Cloud Library (PCL) to build and establish the patient's head surface information, and, through the use of the improved alignment algorithm proposed in this study, the preoperative medical imaging information obtained can be placed in the same world-coordinates system as the patient's head surface information. The traditional alignment method, Iterative Closest Point (ICP), has the disadvantage that an ill-chosen starting position will result only in a locally optimal solution. The proposed improved para-alignment algorithm, named improved-ICP (I-ICP), uses a stochastic perturbation technique to escape from locally optimal solutions and reach the globally optimal solution. After the alignment, the results will be merged and displayed using Microsoft's HoloLens Head-Mounted Display (HMD), and allows the surgeon to view the patient's head at the same time as the patient's medical images. In this study, experiments were performed using spatial reference points with known positions. The experimental results show that the proposed improved alignment algorithm has errors bounded within 3 mm, which is highly accurate.

De-aliasing for signal restoration in Propeller MR imaging.

PURPOSE: Objects falling outside of the true elliptical field-of-view (FOV) in Propeller imaging show unique aliasing artifacts. This study proposes a de-aliasing approach to restore the signal intensities in Propeller images without extra data acquisition. MATERIALS AND METHODS: Computer simulation was performed on the Shepp-Logan head phantom deliberately placed obliquely to examine the signal aliasing. In addition, phantom and human imaging experiments were performed using Propeller imaging with various readouts on a 3.0 Tesla MR scanner. De-aliasing using the proposed method was then performed, with the first low-resolution single-blade image used to find out the aliasing patterns in all the single-blade images, followed by standard Propeller reconstruction. The Propeller images without and with de-aliasing were compared. RESULTS: Computer simulations showed signal loss at the image corners along with aliasing artifacts distributed along directions corresponding to the rotational blades, consistent with clinical observations. The proposed de-aliasing operation successfully restored the correct images in both phantom and human experiments. CONCLUSION: The de-aliasing operation is an effective adjunct to Propeller MR image reconstruction for retrospective restoration of aliased signals.

URGCP/URG4 promotes apoptotic resistance in bladder cancer cells by activating NF-κB signaling.

Cisplatin is a well-known chemotherapeutic agent, it could cause DNA damage and induce apoptotic cell death, but the cisplatin resistance also appears, it's important to reveal the mechanisms of cisplatin resistance [1]. URGCP/URG4 is overexpressed in various tumors and plays critical role during tumor development. We found URGCP/URG4 was upregulated in bladder cancer cells and tissues, URGCP/URG4 overexpression increased the resistance to cisplatin-induced apoptosis in bladder cancer, and promoted anti-apoptotic genes expression, such as Bcl-2, Survivin, MCL-1, FLIP, and downregulated Caspase-3 expression, Knockdown of URGCP/URG4 decreased the resistance to cisplatin-induced apoptosis, and inhibited anti-apoptotic genes expression, such as Bcl-2, Survivin, MCL-1, FLIP, and upregulated Caspase-3 expression. Mechanism analysis found URGCP/URG4 activated NF-κB pathway which is a well-known anti-apoptotic pathway and promoted the expression of NF-κB targeted genes. So we speculated URGCP/URG4 regulates cisplatin-induced apoptosis by activating NF-κB pathway. We also analyzed the correlation between URGCP/URG4 expression and clinical clinicopathologic, and found its expression was positively correlated with bladder cancer progression, it can serve as a valuable prognostic factor. In summary, URGCP/URG4 promotes the resistance to cisplatin-induced apoptosis by activating NF-κB pathway, and is an unfavorable prognostic factor for bladder cancer.

Efficient imaging of midbrain nuclei using inverse double-echo steady-state acquisition.

PURPOSE: Imaging of midbrain nuclei using T2- or T2*-weighted MRI often entails long echo time, leading to long scan time. In this study, an inverse double-echo steady-state (iDESS) technique is proposed for efficiently depicting midbrain nuclei. METHODS: Thirteen healthy subjects participated in this study. iDESS was performed along with two sets of T2*-weighted spoiled gradient-echo images (SPGR1, with scan time identical to iDESS and SPGR2, using clinical scanning parameters as a reference standard) for comparison. Generation of iDESS composite images combining two echo signals was optimized for maximal contrast-to-noise ratio (CNR) between the red nuclei and surrounding tissues. Signal-to-noise ratios (SNRs) were calculated from the occipital lobe. Comparison was also made using phase-enhanced images as in standard susceptibility-weighted imaging (SWI). RESULTS: The iDESS images present significantly higher SNR efficiency (171.3) than SPGR1 (158.7, p = 0.013) and SPGR2 (95.5, p < 10(-8)). iDESS CNR efficiency (19.2) is also significantly greater than SPGR1 (6.9, p < 10(-6)) and SPGR2 (14.3, p = 0.0016). Compared with DESS, iDESS provides further advantage on enhanced phase information and hence improved contrast on SWI-processed images. CONCLUSIONS: iDESS efficiently depicts midbrain nuclei with improved CNR efficiency, increased SNR efficiency, and reduced scan time and is less prone to susceptibility signal loss from air-tissue interfaces.

Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition.

The dual echo steady-state (DESS) sequence has been shown successful in achieving fast T2 mapping with good precision. Under-estimation of T2, however, becomes increasingly prominent as the flip angle decreases. In 3D DESS imaging, therefore, the derived T2 values would become a function of the slice location in the presence of non-ideal slice profile of the excitation RF pulse. Furthermore, the pattern of slice-dependent variation in T2 estimates is dependent on the RF pulse waveform. Multi-slice 2D DESS imaging provides better inter-slice consistency, but the signal intensity is subject to integrated effects of within-slice distribution of the actual flip angle. Consequently, T2 measured using 2D DESS is prone to inaccuracy even at the designated flip angle of 90°. In this study, both phantom and human experiments demonstrate the above phenomena in good agreement with model prediction.

High spatial resolution brain functional MRI using submillimeter balanced steady-state free precession acquisition.

PURPOSE: One of the technical advantages of functional magnetic resonance imaging (fMRI) is its precise localization of changes from neuronal activities. While current practice of fMRI acquisition at voxel size around 3 × 3 × 3 mm(3) achieves satisfactory results in studies of basic brain functions, higher spatial resolution is required in order to resolve finer cortical structures. This study investigated spatial resolution effects on brain fMRI experiments using balanced steady-state free precession (bSSFP) imaging with 0.37 mm(3) voxel volume at 3.0 T. METHODS: In fMRI experiments, full and unilateral visual field 5 Hz flashing checkerboard stimulations were given to healthy subjects. The bSSFP imaging experiments were performed at three different frequency offsets to widen the coverage, with functional activations in the primary visual cortex analyzed using the general linear model. Variations of the spatial resolution were achieved by removing outer k-space data components. RESULTS: Results show that a reduction in voxel volume from 3.44 × 3.44 × 2 mm(3) to 0.43 × 0.43 × 2 mm(3) has resulted in an increase of the functional activation signals from (7.7 ± 1.7)% to (20.9 ± 2.0)% at 3.0 T, despite of the threefold SNR decreases in the original images, leading to nearly invariant functional contrast-to-noise ratios (fCNR) even at high spatial resolution. Activation signals aligning nicely with gray matter sulci at high spatial resolution would, on the other hand, have possibly been mistaken as noise at low spatial resolution. CONCLUSIONS: It is concluded that the bSSFP sequence is a plausible technique for fMRI investigations at submillimeter voxel widths without compromising fCNR. The reduction of partial volume averaging with nonactivated brain tissues to retain fCNR is uniquely suitable for high spatial resolution applications such as the resolving of columnar organization in the brain.

Frequency stabilization using infinite impulse response filtering for SSFP fMRI at 3T.

The steady-state free precession (SSFP) method has been shown to exhibit strong potential for distortion-free functional magnetic resonance imaging (fMRI). One major challenge of SSFP fMRI is that the frequency band corresponding to the highest functional sensitivity is extremely narrow, leading to substantial loss of functional contrast in the presence of magnetic field drifts. In this study we propose a frequency stabilization scheme whereby an RF pulse with small flip angle is applied before each image scan, and the initial phase of the free induction decay (FID) signals is extracted to reflect temporal field drifts. A simple infinite impulse response (IIR) filter is further employed to obtain a low-pass-filtered estimate of the central reference frequency for the upcoming scan. Experimental results suggest that the proposed scheme can stabilize the frequency settings in accordance with field drifts, with oscillation amplitudes of <0.5 Hz. Phantom studies showed that both slow drifts and fast fluctuations were prominently reduced, resulting in less than 5% signal variations. Visual fMRI at submillimeter in-plane resolution further demonstrated 15% activation signals that were nicely registered in the microvessels within the sulci. It is concluded that the IIR-filtered frequency stabilization is an effective technique for achieving reliable SSFP fMR images at high field strengths.

Tensor deflection (TEND) tractography with adaptive subvoxel stepping.

PURPOSE: To develop an adaptive subvoxel stepping scheme, as an adjunct to tensor deflection (TEND) tractography, that automatically adjusts the stepping size by considering the tensor linearity to properly trace fiber bundles in regions with different degrees of tensor anisotropy. MATERIALS AND METHODS: A theoretical investigation of the TEND algorithm was performed to assess the degree of deflection of the propagation vector toward the major eigenvector. Mathematically generated phantoms (one with curved fibers and the other with crossing fibers) at wide ranges of signal-to-noise ratio (SNR), and human brain images obtained in vivo were used to test the performance of the adaptive stepping algorithm. RESULTS: The degree of deflection was found to be inversely related to the stepping size. A small stepping size was advantageous for tracing single curved fiber bundles, whereas a large stepping size was beneficial for passing through fiber crossing regions. The performance of the adaptive stepping algorithm was superior to fixed stepping in both situations, leading to an approximately 0.17 voxel of deviation in curved fibers and a nearly 100% successful tracking rate in crossing fibers at typical SNR. Human brain images demonstrated similar results. CONCLUSION: The adaptive stepping algorithm is a helpful adjunct to TEND tractography.

Application of model-free analysis in the MR assessment of pulmonary perfusion dynamics.

Dynamic contrast-enhanced (DCE) MRI has been used to quantitatively evaluate pulmonary perfusion based on the assumption of a gamma-variate function and an arterial input function (AIF) for deconvolution. However, these assumptions may be too simplistic and may not be valid in pathological conditions, especially in patients with complex inflow patterns (such as in congenital heart disease). Exploratory data analysis methods make minimal assumptions on the data and could overcome these pitfalls. In this work, two temporal clustering methods--Kohonen clustering network (KCN) and Fuzzy C-Means (FCM)--were concatenated to identify pixel time-course patterns. The results from seven normal volunteers show that this technique is superior for discriminating vessels and compartments in the pulmonary circulation. Patient studies with five cases of acquired or congenital pulmonary perfusion disorders demonstrate that pathologies can be highlighted in a concise map that combines information of the mean transit time (MTT) and pulmonary blood volume (PBV). The method was found to provide greater insight into the perfusion dynamics that might be overlooked by current model-based analyses, and may serve as a basis for optimal hemodynamic quantitative modeling of the interrogated perfusion compartments.

MR ventriculocisternography by using 3D balanced steady-state free precession imaging: technical note.

This study investigated the effects of flip angle setting in 3D balanced steady-state free precession (SSFP) imaging on CSF-parenchyma contrast and section aliasing artifacts. Theoretical derivations indicated that the extent of section aliasing artifacts decreased as the flip angle was lowered, at the expense of a sacrifice in CSF-parenchyma contrast. Experimental data agreed closely with theoretical predictions. A flip angle of about 40 degrees is therefore recommended for 3D balanced SSFP MR ventriculocisternography.

Hippocampal alterations in children with temporal lobe epilepsy with or without a history of febrile convulsions: evaluations with MR volumetry and proton MR spectroscopy.

BACKGROUND AND PURPOSE: The causal effect of early febrile convulsions (FC) on later-onset temporal lobe epilepsy (TLE) remains unclear. In this study, we sought to examine the hippocampal alterations in epileptic children with or without FC history by using MR spectroscopy and volumetry. METHODS: Fifty-five children ranging in age from 18 months to 15 years were enrolled in this study. Subjects were divided into three groups: the control group without either TLE or history of FC (n = 16), the TLE group with early history of FC (TLE + FC; n = 22), and the TLE group without FC history (n = 17). Measurement of hippocampal volume (HV) was performed on thin section T1-weighted images acquired with a 3D gradient echo MR image and normalized by the intracranial volume. Each individual subject had two measures of lateralization; one gives the smaller side of HV and the other the contralateral larger side of HV, assuming that the side with smaller HV is the possible primary site of seizure focus and the contralateral larger HV the secondary or normal site. Single-voxel proton MR spectroscopy of the hippocampi was performed, with metabolic ratio n-acetylaspartate (NAA)/choline (Cho) + creatine plus phosphocreatine (Cr) calculated and grouped separately as were with volumetry. RESULTS: The overall mean HV for the control group was 2.61 +/- 0.21 cm(3) at an average intracranial volume of 965 +/- 241 cm(3), and the asymmetry index for hippocampal volume was (2.32 +/- 1.58)%. The overall mean HV was 2.30 +/- 0.33 cm(3) for TLE + FC group and 2.34 +/- 0.33 cm(3) for TLE group. Mean HV differed significantly for the three groups (P < .01). When the small and large sides were analyzed separately, significant differences were found between control and TLE as well as between control and TLE + FC for the smaller side (P < .05), whereas for the larger side significant differences were found only between control and TLE + FC. In MR spectroscopic measurements, the mean NAA/(Cr + Cho) of bilateral hippocampi was 0.77 +/- 0.06 for control group, 0.62 +/- 0.12 for TLE + FC group, and 0.66 +/- 0.11 for TLE group. In terms of statistically significant difference between groups, spectroscopic results were similar to volumetric measurements, except that there was no significant interaction effect between groups and measures of asymmetrical indices (P = .272). CONCLUSION: Children with TLE and early history of FC tend to have lower hippocampal volumes and NAA/(Cr + Cho) ratios than do TLE children without FC history. The TLE + FC group seems to have increased vulnerability of the contralateral hippocampus as compared with TLE group. MR volumetry and spectroscopy are equally capable of showing the trends of hippocampal alternations in children with TLE with or without FC history.