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Swept-source optical coherence tomography (SS-OCT) is widely used to diagnose high myopia due to its advantage in imaging the ocular anatomic structures. Although the scleral deformation provides information on the risk of the high myopia, further validation of these highly promising findings in clinical studies has been limited by the current semi-automated software, which requires human input, and the automatic analysis of the scleral structure is quite challenging due to the ambiguous boundaries. To address these challenges, we propose a deep contour attention network (DCANet) for automatic segmentation of scleral deformation structure. Specifically, we design a scale-aware attention feature fusion module to achieve cross-scale feature fusion, which can facilitate the network to learn complementary information from multi-scale features. In addition, we develop a pyramid feature enhancement module to allow the network to learn global contextual features through the combination of receptive field and attention mechanism, and we also propose a boundary heatmap label to enrich boundary information. We evaluate the performance of the proposed method on two in-house SS-OCT datasets. In addition to the multiple metrics that are used for evaluating the segmentation performance, including Jaccard similarity coefficient, dice similarity coefficient and boundary distance error, we also propose length similarity coefficient and angle similarity coefficient to evaluate the length estimation and angle estimation, respectively. The experimental results show that our method can effectively improve the segmentation performance, and our DCANet achieves the overall best performance on two datasets compared with other state-of-the-art networks. Our findings motivate the development of clinically applicable deep learning systems for the prediction of high myopia progression on the basis of the scleral phenotypes from SS-OCT images. [ABSTRACT FROM AUTHOR]

Reflectivity is a key topic in soft X-ray optics research and serves as the foundation for studying the performance of the optics for X-ray astronomical satellites. Since its establishment, the 100-m X-ray Test Facility (100XF) has been continuously developing various testing functionalities, including calibration of timing, imaging, and energy response. This paper provides a detailed description of the X-ray optics reflectivity test method based on the 100XF, which can be applied to various grazing incident X-ray optics, including Wolter-I and lobster-eye types, significantly expanding the application scope of the 100XF. A flat mirror sample (SiO 2 coated on a Si wafer) is tested. Results of the variation of reflectivity with angle @ C-K α (0.28 keV), Al-K α (1.49 keV), and Ti-K α (4.50 keV) are presented in the description. The reflectivity test method has also been applied to the coating reflectivity study of the enhanced X-ray Timing and Polarimetry Mission (eXTP) mirror. At the same time, a new method utilizing the continuum spectrum of bremsstrahlung was carried out to study the continuous variation of reflectivity with energy, greatly improving efficiency compared to traditional methods, and all the results show a good agreement with the theoretical values. The deviation between the test and theoretical values in the low-energy range (1.5-8.0 keV) is less than 10%. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to identify the possible association between mental status and the risk of self-reported asthenopia among college students in China. Methods: Ten thousand students were randomly assessed in the study using a self-reported asthenopia questionnaire. Their demographic characteristics and mental status were recorded. Univariate analysis was performed to preliminarily select potential risk and protective factors. Then, multivariate logistic regression was used to estimate odds ratios for the selected risk factors of interest. Results: Among the 8370 students who completed the survey, the prevalence of asthenopia was 61.0%. Multivariate analysis revealed a significant relationship between asthenopia and depressive symptoms (OR 1.511 95% CI: 1.350–1.691), obsessive-compulsive symptoms (OR 1.477, 95% CI: 1.338–1.632), gender and study load. The place college students spent their off-hours (OR 0.841, 95% CI: 0.784–0.902) was found to be the strongest factor for decreasing the occurrence of asthenopia complaints. Conclusion: Asthenopia appears common in Chinese college students. In addition to depressive symptoms, we should pay attention to obsessive-compulsive symptoms when considering means of preventing asthenopia. Harmonious social relationships, outdoor off-hour activities and exercising more than three times per week are crucial to relieving visual fatigue. Further study is still needed in this area. Key message: What is known: • Past studies reported a significant association between mental health and asthenopia, suggesting that mental health acts as a protective factor against asthenopia. What is new: • This large cross-sectional study of 10,000 people found that the prevalence of asthenopia among college students reached 61%, up from 57% in previous studies(2011s). • This study revealed a significant relationship between asthenopia and depressive symptoms, obsessive-compulsive symptoms, gender and study load. • The place college students spent their off-hours was found to be the strongest factor for decreasing the occurrence of asthenopia complaints. [ABSTRACT FROM AUTHOR]

The enhanced X-ray Timing and Polarimetry mission (eXTP) is a next-generation flagship X-ray astronomy satellite currently in phase-B study. The large Area Detector (LAD) on board eXTP contains 40 modules, each consisting of a set of 4 × 4 large area SDDs and 4 × 4 collimators, and has a designed effective area of 3.0 m 2 at 8 keV and a Field of View (FoV) of 1 ∘ . To achieve such a large effective area, the collimator’s Open Area Ratio (OAR) should be greater than 70%. In this paper, we introduce the measurement methods used to determine the OAR and the rocking curve (angular response) of the LAD collimator at the 100-m X-ray Test Facility (100XF) of the Institute of High Energy Physics (IHEP) in Beijing, and report the results of the collimators manufactured under different conditions. The measured OARs of the collimators are usually smaller than the theoretical values by a few percent, which is due to the non-uniformity and irregularity of the pores. The measured rocking curves are usually broader than the theoretical triangular curves, and the lower the energy of the incident X-ray the broader the rocking curve. This broadening of the rocking curve is the result of reflection on the inner wall of the pores. Our results also show that increasing the etching time in the manufacturing of the collimators can increase the OARs but does not change significantly the shape of the rocking curves. [ABSTRACT FROM AUTHOR]

The spectroscopy focusing array is one of the four main scientific instruments of the enhanced X-ray Timing and Polarimetry mission, tasked with spectral and timing observation in the energy range 0.5-10 keV. An engineering model of the spectroscopy focusing array with a 4 mirror shells assembly and a focal plane detector using commercial detectors has now been developed. To evaluate the performance, the spectral and timing calibration of the engineering model has been held in the 100-m X-ray Test Facility. A multi-target X-ray source with multiple emission lines is used to calibrate the spectral performance. A timing X-ray source based on a grid controlled X-ray tube has been utilized for the timing calibration. The timing X-ray source can generate X-ray pulses to measure the response time distribution, and can also simulate the pulsar lightcurves to examine the detection ability for pulsars. The energy-channel relation and energy resolution are determined through spectral calibration. The energy resolution at 5.95 keV is 142 eV, now. According to the timing calibration, the mean response time of the engineering model is 1.55 μ s, the full width at half maximum of the response time distribution is 0.45 μ s, and the engineering model has sufficient ability to detect the profile of millisecond pulsars. [ABSTRACT FROM AUTHOR]

The 100-m X-ray Test Facility (100XF) was developed according to the calibration requirement of the first X-ray astronomical satellite Insight-HXMT in china. After that, the 100XF has provided calibration services for other X-ray astronomical satellites. In order to test the energy response matrices of space-borne detectors and to extend the capability of 100XF, a monochromator based on channel-cut crystals is developed. So far, 3.0-20.7 keV monochromatic X-rays have been realized successfully with Si(111) crystal. The monochromaticity (Δ E FWHM /E) is better than 0.6% @5.9 keV, the flux stability can reach 2.6% in about one hour. The energy stability is particularly good, the variation is 0.05% in about one hour. Further more, the beam spot spreads in the plane orthogonal to the rocking direction after a propagation of 100-meter, which is sufficient and useful for testing detectors with large sensitive area. In this paper, we present the research and establishment of the X-ray monochromator at the 100XF. [ABSTRACT FROM AUTHOR]

The Low Energy X-ray telescope (LE) is one of the main instruments of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), the first Chinese X-ray astronomical satellite. The scientific objectives of LE focus on scanning and pointed observations of the X-ray sources in the soft X-ray band (0.7–13 keV). LE consists of three detector boxes (LEDs) and an electric control box (LEB). The LEB is composed of data handling unit, monitoring unit, and power distribution unit, with functions including data processing, communication, monitoring, power supply, and distribution. All the functions designed in the LEB were verified during the operation in orbit. To improve the efficiency of astronomical observations and reliability of LE, onboard data processing is designed in the LEB. The results of onboard data processing are immediately transmitted to the ground as important housekeeping data and are verified by comparing them with the processing results of the data transmitted to the ground. In the six years since launch, the LEB has performed well, operated smoothly, and met all expected requirements. The LEB has participated in numerous scientific observations, transmitted a large amount of scientific data, and obtained several observational results. [ABSTRACT FROM AUTHOR]

An observation simulator is established for the Spectroscopy Focusing Array (SFA) and Polarimetry Focusing Array (PFA) onboard the planned enhanced X-ray Timing and Polarimetry observatory (eXTP). It consists of photon generation, imaging, detection, and event readout to generate data products, which can be analyzed by the standard astronomical analysis software. It is used to simulate a few astronomical sources to estimate and understand the impact of the payload and platform design configurations on the scientific goals of eXTP, including the background estimation of the central pixel in SFA, position dependence of silicon drift detector signals and its impacts, and pointing jitter requirements. The joint data analysis of the SFA and PFA payloads shows that the PFA image can help estimate the impact of nearby sources on the target source and select the proper pixels for the background estimation of the central pixel in SFA. The spectral and timing study of the millisecond pulsar depicts that the position dependence of silicon drift detector signals itself has an insignificant impact on the results. The type-C low-frequency quasi-periodic oscillations of black holes ranging from 0.01 Hz to 30 Hz are considered to raise the pointing jitter requirements of the telescope. In this case, the stability of the telescope should be less than 12 ″ to avoid any spurious modulation signal. These examples demonstrate the necessity of an end-to-end observation simulator in the space mission, which will be further tested and improved by the ground segment in a wider range of applications. [ABSTRACT FROM AUTHOR]

Hyperreflective foci (HF) reflects inflammatory responses for fundus diseases such as diabetic macular edema (DME), retina vein occlusion (RVO), and central serous chorioretinopathy (CSC). Shown as high contrast and reflectivity in optical coherence tomography (OCT) images, automatic segmentation of HF in OCT images is helpful for the prognosis of fundus diseases. Previous traditional methods were time-consuming and required high computing power. Hence, we proposed a lightweight network to segment HF (with a speed of 57 ms per OCT image, at least 150 ms faster than other methods). Our framework consists of two stages: an NLM filter and patch-based split to preprocess images and a lightweight DBR neural network to segment HF automatically. Experimental results from 3000 OCT images of 300 patients (100 DME,100 RVO, and 100 CSC) revealed that our method achieved HF segmentation successfully. The DBR network had the area under curves dice similarity coefficient (DSC) of 83.65%, 76.43%, and 82.20% in segmenting HF in DME, RVO, and CSC on the test cohort respectively. Our DBR network achieves at least 5% higher DSC than previous methods. HF in DME was more easily segmented compared with the other two types. In addition, our DBR network is universally applicable to clinical practice with the ability to segment HF in a wide range of fundus diseases. [ABSTRACT FROM AUTHOR]

The 100-m X-ray Test Facility of the Institute of High Energy Physics (IHEP) was initially proposed in 2012 for the test and calibration of the X-ray detectors of the Hard X-ray Modulation Telescope (HXMT) with the capability to support future X-ray missions. The large instrument chamber connected with a long vacuum tube can accommodate the X-ray mirror, focal plane detector and other instruments. The X-ray sources are installed at the other end of the vacuum tube with a distance of 105 m, which can provide an almost parallel X-ray beam covering 0.2 ∼ 60 keV energy band. The X-ray mirror modules of the Einstein Probe (EP) and the enhanced X-ray Timing and Polarimetry mission (eXTP) and payload of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) have been tested and calibrated with this facility. It has been also used to characterize the focal plane camera and aluminum filter used on the Einstein Probe. In this paper, we will introduce the overall configuration and capability of the facility, and give a brief introduction of some calibration results performed with this facility. [ABSTRACT FROM AUTHOR]

The main scientific goal of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is to monitor various types of Gamma-Ray Bursts (GRB) originated from merger of binary compact stars, which could also produce gravitational wave, and collapse of massive stars. In order to study the response of GECAM Gamma-Ray Detectors (GRDs) to high-energy bursts and test the in-flight trigger and localization software of GECAM before the launch, a portable GRB simulator device is designed and implemented based on grid controlled X-ray tube (GCXT) and direct digital synthesis (DDS) technologies. The design of this GRB simulator which modulates X-ray flux powered by high voltage up to 20 kV is demonstrated, and the time jitter (FWHM) of the device is about 0.9 μs. Before the launch in December, 2020, both two GECAM satellites were irradiated by different types of GRBs (including short and long bursts in duration) generated by this GRB simulator. The light curves detected with GECAM/GRDs are consistent with the programmed input functions within statistical uncertainties, indicating the good performance of both the GRDs and the GRB simulator. [ABSTRACT FROM AUTHOR]

Charged particles in the space environment can degrade the scientific performances of X-ray detectors in astronomical telescopes. An efficient countermeasure is to place a magnetic diverter at the exit pupil of optics to deflect charged particles away from the sensitive detection area. In this work, we have performed a preliminary design of the magnetic diverter on-board the enhanced X-ray Timing and Polarimetry (eXTP) observatory. It relies on a Monte Carlo method via the GEANT4 toolkit to simulate the mirror responses to charged particles, using the single scattering physics for electrons and the elastic Remizovich physics for protons. It also implements a numerical method to calculate magnetic fields generated by an assembly of permanent magnets and its impact on the trajectories of charged particles. The compact calculation scheme provides efficient access to the background level estimation given the certain radiation environment, which enables the verification of the diverter configuration with the scientific requirements. [ABSTRACT FROM AUTHOR]

To evaluate the application of machine learning for the detection of subpleural pulmonary lesions (SPLs) in ultrasound (US) scans, we propose a novel boundary-restored network (BRN) for automated SPL segmentation to avoid issues associated with manual SPL segmentation (subjectivity, manual segmentation errors, and high time consumption). In total, 1612 ultrasound slices from 255 patients in which SPLs were visually present were exported. The segmentation performance of the neural network based on the Dice similarity coefficient (DSC), Matthews correlation coefficient (MCC), Jaccard similarity metric (Jaccard), Average Symmetric Surface Distance (ASSD), and Maximum symmetric surface distance (MSSD) was assessed. Our dual-stage boundary-restored network (BRN) outperformed existing segmentation methods (U-Net and a fully convolutional network (FCN)) for the segmentation accuracy parameters including DSC (83.45 ± 16.60%), MCC (0.8330 ± 0.1626), Jaccard (0.7391 ± 0.1770), ASSD (5.68 ± 2.70 mm), and MSSD (15.61 ± 6.07 mm). It also outperformed the original BRN in terms of the DSC by almost 5%. Our results suggest that deep learning algorithms aid fully automated SPL segmentation in patients with SPLs. Further improvement of this technology might improve the specificity of lung cancer screening efforts and could lead to new applications of lung US imaging. [ABSTRACT FROM AUTHOR]

The Low Energy X-ray telescope (LE) is one of the three main instruments of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT). It is equipped with Swept Charge Device (SCD) sensor arrays with a total geometrical area of 384 cm and an energy band from 0.7 to 13 keV. In order to evaluate the particle induced X-ray background and the cosmic X-ray background simultaneously, LE adopts collimators to define four types of Field Of Views (FOVs), i.e., 1.6°×6°, 4°×6°, 50°-60°×2°-6° and the blocked ones which block the X-ray by an aluminum cover. LE is constituted of three detector boxes (LEDs) and an electric control box (LEB) and achieves a good energy resolution of 140 eV@5.9 keV, an excellent time resolution of 0.98 ms, as well as an extremely low pileup (<1%@18000 cts/s). Detailed performance tests and calibration on the ground have been performed, including energy-channel relation, energy response, detection efficiency and time response. [ABSTRACT FROM AUTHOR]

The Insight-Hard X-ray Modulation Telescope (Insight-HXMT) is a broadband X-ray and γ-ray (1-3000 keV) astronomy satellite. One of its three main telescopes is the High Energy X-ray telescope (HE). The main detector plane of HE comprises 18 NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) is used as the primary detector to measure ~ 20–250 keV photons incident from the field of view (FOV) defined by collimators, and CsI(Na) is used as the active shielding detector to NaI(Tl) by pulse shape discrimination. Additionally, CsI(Na) is used as an omnidirectional γ-ray monitor. The HE collimators have a diverse FOV, i.e. 1.1°×5.7° (15 units), 5.7°×5.7° (2 units), and blocked (1 unit). Therefore, the combined FOV of HE is approximately 5.7°×5.7°. Each HE detector has a diameter of 190 mm resulting in a total geometrical area of approximately 5100 cm2, and the energy resolution is ~15% at 60 keV. For each recorded X-ray event by HE, the timing accuracy is less than 10 μs and the dead-time is less than 10 μs. HE is used for observing spectra and temporal variability of X-ray sources in the 20–250 keV band either by pointing observations for known sources or scanning observations to unveil new sources. Additionally, HE is used for monitoring the γ-ray burst in 0.2-3 MeV band. This paper not only presents the design and performance of HE instruments but also reports results of the on-ground calibration experiments. [ABSTRACT FROM AUTHOR]

As China’s first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results. [ABSTRACT FROM AUTHOR]

The Medium Energy X-ray telescope (ME) is one of the three main telescopes on board the Insight hard X-ray modulation telescope (Insight-HXMT) astronomy satellite. ME contains 1728 pixels of Si-PIN detectors sensitive in 5–30 keV with a total geometrical area of 952 cm2. The application specific integrated circuit (ASIC) chip, VA32TA6, is used to achieve low power consumption and low readout noise. The collimators define three kinds of field of views (FOVs) for the telescope, 1°×4°, 4°×4°, and blocked ones. Combination of such FOVs can be used to estimate the in-orbit X-ray and particle background components. The energy resolution of ME is ~3 keV at 17.8 keV (FWHM) and the time resolution is 255 μs. In this paper, we introduce the design and performance of ME. [ABSTRACT FROM AUTHOR]

Double layer micro-channel heat sink (DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overall stability. In this paper, two optimized designs of DLMCHS with cutting baffles on top and bottom layers are presented based on the traditional DLMCHS. The heat transfer and thermal stress performance are numerically analyzed and compared with the traditional DLMCHS. The results indicate that cutting baffles of micro-channels remarkably improves heat transfer and thermal stress performance. The optimized design with cutting baffles on the bottom layer decreases thermal strain but deteriorates heat transfer performance. The model with cutting baffles on the top layer has better combined thermal strain and heat transfer performance, which reduces thermal strain by about 1.5 times and enhances heat transfer by about 26.5%. For the design with cutting baffles on the top board, adding metal foam in the inlet collector can decrease the total minimum thermal strain by 51.4% and maximum temperature by 1.4 K, and increase the Nusselt number by 15%. These results indicate that DLMCHS with cutting baffles on the top layer has great potential for thermal managements on electronic devices with high power density. [ABSTRACT FROM AUTHOR]

Based on the thermo-electric analogy (the so-called thermal entransy analysis), the unified airside convective heat transfer coefficient for different sorts of flat plate solar air collectors (FPSACs) is identified in terms of collector aperture area. In addition, the collector thermodynamic characteristic matching coefficient is defined to depict the matching property of collector thermal performance between the collector airside heat transfer and the total heat losses. It is found that the airside convective heat transfer coefficient can be experimentally determined by collector thermal performance test method to compare the airside thermal performances of FPSACs with different types of airflow structures. Moreover, the smaller the collector thermodynamic characteristic matching coefficient is, the better the thermodynamic perfect degree of a FPSAC is. The minimum limit value of the collector thermodynamic matching coefficient is close to zero but it can not vanish in practical engineering. Parameter sensitivity analysis on the total entransy dissipation and the entransy increment of a general FPSAC is also undertaken. The results indicate that the effective way of decreasing total entransy dissipation and enhancing the useful entransy increment is improving the efficiency intercept of the FPSAC. This is equivalent to the cognition result of thermal analysis. However, the evaluation indices identified by the thermal entransy analysis can not be extracted by singular thermal analysis. [ABSTRACT FROM AUTHOR]

Based on a typical single pass flat plate solar air collector (FPSAC) model, the collector thermodynamic characteristic matching property between the air-side heat transfer and total heat losses is analyzed in terms of unified air-side heat transfer coefficient U and total heat loss coefficient U . Then the limit design principle of FPSACs is discussed in order to obtain high collector efficiency intercepts. The results show that, both lower and upper limit values of U exist for obtaining an expected efficiency intercept (η) which is lower than the maximum realizable intercept ((η)) with specific collector components. The case of maximum realizable intercept (η) can be obtained by the minimum realizable total heat loss coefficient ( U ) and a high convective heat transfer coefficient U ( U = 200 W/(m·K) is argued to be good collector air-side thermal performance and is considered in the present study), resulting in a minimum thermodynamic characteristic coefficient ζ. And the maximum realizable intercepts for different component combination cases of FPSACs are obtained by numerical calculation. Besides, for FPSACs with specific airflow channels, the cases of minimum realizable ( U ) represent the limit design. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to investigate branched-chain amino acid (BCAA) catabolism in diabetic retinopathy (DR).Wild-type and db/db mice were fed BCAAs (5 or 10 mg/kg/day) for 12 weeks, and hyperglycemia-exposed Müller cells were treated with BCAAs (2 or 5 mmol/L) for 24 and 48 h. BCAA levels were measured using MS/MS. Western blotting was performed to detect proteins. Flow cytometry, oxygen consumption rate, and Cell Counting Kit-8 assays were used to evaluate Müller cell viability. Each experiment was conducted at least thrice.BCAAs and branched-chain α-keto acids (BCKAs) were increased in the retina and systemic tissues of diabetic mice, and these changes were further enhanced to approximately 2-fold by extra BCAAs compared to wild-type group. In vitro, BCAAs and BCKAs were induced in hyperglycemic Müller cells, and augmented by BCAA supplementation. The aberrant BCAA catabolism was accompanied by mTORC1 activation and subsequently induced TNF-ɑ, VEGFA, GS, and GFAP in retinas and Müller cells under diabetic conditions. The cell apoptosis rate increased by approximately 50%, and mitochondrial respiration was inhibited by hyperglycemia and BCAA in Müller cells. Additionally, mTORC1 signaling was activated by leucine in Müller cells. Knockdown of Sestrin2 or LeuRS significantly abolished the leucine-induced mTORC1 phosphorylation and protected Müller cell viability under diabetic conditions.We found that BCAA catabolism is hindered in DR through mTORC1 activation. Leucine plays a key role in inducing mTORC1 by sensing Sestrin2 in Müller cells. Targeting Sestrin2 may ameliorate the toxic effects of BCAA accumulation on Müller cells in DR.Methods: This study aimed to investigate branched-chain amino acid (BCAA) catabolism in diabetic retinopathy (DR).Wild-type and db/db mice were fed BCAAs (5 or 10 mg/kg/day) for 12 weeks, and hyperglycemia-exposed Müller cells were treated with BCAAs (2 or 5 mmol/L) for 24 and 48 h. BCAA levels were measured using MS/MS. Western blotting was performed to detect proteins. Flow cytometry, oxygen consumption rate, and Cell Counting Kit-8 assays were used to evaluate Müller cell viability. Each experiment was conducted at least thrice.BCAAs and branched-chain α-keto acids (BCKAs) were increased in the retina and systemic tissues of diabetic mice, and these changes were further enhanced to approximately 2-fold by extra BCAAs compared to wild-type group. In vitro, BCAAs and BCKAs were induced in hyperglycemic Müller cells, and augmented by BCAA supplementation. The aberrant BCAA catabolism was accompanied by mTORC1 activation and subsequently induced TNF-ɑ, VEGFA, GS, and GFAP in retinas and Müller cells under diabetic conditions. The cell apoptosis rate increased by approximately 50%, and mitochondrial respiration was inhibited by hyperglycemia and BCAA in Müller cells. Additionally, mTORC1 signaling was activated by leucine in Müller cells. Knockdown of Sestrin2 or LeuRS significantly abolished the leucine-induced mTORC1 phosphorylation and protected Müller cell viability under diabetic conditions.We found that BCAA catabolism is hindered in DR through mTORC1 activation. Leucine plays a key role in inducing mTORC1 by sensing Sestrin2 in Müller cells. Targeting Sestrin2 may ameliorate the toxic effects of BCAA accumulation on Müller cells in DR.Results: This study aimed to investigate branched-chain amino acid (BCAA) catabolism in diabetic retinopathy (DR).Wild-type and db/db mice were fed BCAAs (5 or 10 mg/kg/day) for 12 weeks, and hyperglycemia-exposed Müller cells were treated with BCAAs (2 or 5 mmol/L) for 24 and 48 h. BCAA levels were measured using MS/MS. Western blotting was performed to detect proteins. Flow cytometry, oxygen consumption rate, and Cell Counting Kit-8 assays were used to evaluate Müller cell viability. Each experiment was conducted at least thrice.BCAAs and branched-chain α-keto acids (BCKAs) were increased in the retina and systemic tissues of diabetic mice, and these changes were further enhanced to approximately 2-fold by extra BCAAs compared to wild-type group. In vitro, BCAAs and BCKAs were induced in hyperglycemic Müller cells, and augmented by BCAA supplementation. The aberrant BCAA catabolism was accompanied by mTORC1 activation and subsequently induced TNF-ɑ, VEGFA, GS, and GFAP in retinas and Müller cells under diabetic conditions. The cell apoptosis rate increased by approximately 50%, and mitochondrial respiration was inhibited by hyperglycemia and BCAA in Müller cells. Additionally, mTORC1 signaling was activated by leucine in Müller cells. Knockdown of Sestrin2 or LeuRS significantly abolished the leucine-induced mTORC1 phosphorylation and protected Müller cell viability under diabetic conditions.We found that BCAA catabolism is hindered in DR through mTORC1 activation. Leucine plays a key role in inducing mTORC1 by sensing Sestrin2 in Müller cells. Targeting Sestrin2 may ameliorate the toxic effects of BCAA accumulation on Müller cells in DR.Conclusions: This study aimed to investigate branched-chain amino acid (BCAA) catabolism in diabetic retinopathy (DR).Wild-type and db/db mice were fed BCAAs (5 or 10 mg/kg/day) for 12 weeks, and hyperglycemia-exposed Müller cells were treated with BCAAs (2 or 5 mmol/L) for 24 and 48 h. BCAA levels were measured using MS/MS. Western blotting was performed to detect proteins. Flow cytometry, oxygen consumption rate, and Cell Counting Kit-8 assays were used to evaluate Müller cell viability. Each experiment was conducted at least thrice.BCAAs and branched-chain α-keto acids (BCKAs) were increased in the retina and systemic tissues of diabetic mice, and these changes were further enhanced to approximately 2-fold by extra BCAAs compared to wild-type group. In vitro, BCAAs and BCKAs were induced in hyperglycemic Müller cells, and augmented by BCAA supplementation. The aberrant BCAA catabolism was accompanied by mTORC1 activation and subsequently induced TNF-ɑ, VEGFA, GS, and GFAP in retinas and Müller cells under diabetic conditions. The cell apoptosis rate increased by approximately 50%, and mitochondrial respiration was inhibited by hyperglycemia and BCAA in Müller cells. Additionally, mTORC1 signaling was activated by leucine in Müller cells. Knockdown of Sestrin2 or LeuRS significantly abolished the leucine-induced mTORC1 phosphorylation and protected Müller cell viability under diabetic conditions.We found that BCAA catabolism is hindered in DR through mTORC1 activation. Leucine plays a key role in inducing mTORC1 by sensing Sestrin2 in Müller cells. Targeting Sestrin2 may ameliorate the toxic effects of BCAA accumulation on Müller cells in DR. [ABSTRACT FROM AUTHOR]