Optical projection tomography reconstruction with few views using highly-generalizable deep learning at sinogram domain.

Optical projection tomography (OPT) reconstruction using a minimal number of measured views offers the potential to significantly reduce excitation dosage and greatly enhance temporal resolution in biomedical imaging. However, traditional algorithms for tomographic reconstruction exhibit severe quality degradation, e.g., presence of streak artifacts, when the number of views is reduced. In this study, we introduce a novel domain evaluation method which can evaluate the domain complexity, and thereby validate that the sinogram domain exhibits lower complexity as compared to the conventional spatial domain. Then we achieve robust deep-learning-based reconstruction with a feedback-based data initialization method at sinogram domain, which shows strong generalization ability that notably improves the overall performance for OPT image reconstruction. This learning-based approach, termed SinNet, enables 4-view OPT reconstructions of diverse biological samples showing robust generalization ability. It surpasses the conventional OPT reconstruction approaches in terms of peak-signal-to-noise ratio (PSNR) and structural similarity (SSIM) metrics, showing its potential for the augment of widely-used OPT techniques.

Activation of RARα Receptor Attenuates Neuroinflammation After SAH via Promoting M1-to-M2 Phenotypic Polarization of Microglia and Regulating Mafb/Msr1/PI3K-Akt/NF-κB Pathway.

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) is a life-threatening subtype of stroke with high rates of mortality. In the early stages of SAH, neuroinflammation is one of the important mechanisms leading to brain injury after SAH. In various central nervous system diseases, activation of RARα receptor has been proven to demonstrate neuroprotective effects. This study aimed to investigate the anti-inflammatory effects of RARα receptor activation after SAH. METHODS: Internal carotid artery puncture method used to established SAH model in Sprague-Dawley rats. The RARα specific agonist Am80 was injected intraperitoneally 1 hour after SAH. AGN196996 (specific RARα inhibitor), Msr1 siRNA and LY294002 (PI3K-Akt inhibitor) were administered via the lateral ventricle before SAH. Evaluation SAH grade, neurological function score, blood-brain barrier permeability. BV2 cells and SH-SY5Y cells were co-cultured and stimulated by oxyhemoglobin to establish an in vitro model of SAH. RT-PCR, Western blotting, and immunofluorescence staining were used to investigate pathway-related proteins, microglia activation and inflammatory response. Results: The expression of RARα, Mafb, and Msr1 increased in rat brain tissue after SAH. Activation of the RARα receptor with Am80 improved neurological deficits and attenuated brain edema, blood brain barrier permeability. Am80 increased the expression of Mafb and Msr1, and reduced neuroinflammation by enhancing the phosphorylation of Akt and by inhibiting the phosphorylation of NF-κB. AGN196996, Msr1 siRNA, and LY294002 reversed the therapeutic effects of Am80 by reducing the expression of Msr1 and the phosphorylation of Akt. In vitro model of SAH, Am80 promoted M1-to-M2 phenotypic polarization in microglia and suppressed the nuclear transcription of NF-κB. CONCLUSION: Activation of the RARα receptor attenuated neuroinflammation by promoting M1-to-M2 phenotypic polarization in microglia and regulating the Mafb/Msr1/PI3K-Akt/NF-κB pathway. RARα might serve as a potential target for SAH therapy.

ACEA Attenuates Oxidative Stress by Promoting Mitophagy via CB1R/Nrf1/PINK1 Pathway after Subarachnoid Hemorrhage in Rats.

METHOD: Endovascular perforation was performed to establish a SAH model of rats. ACEA was administered intraperitoneally 1 h after SAH. The CB1R antagonist AM251 was injected intraperitoneally 1 h before SAH induction. Adenoassociated virus- (AAV-) Nrf1 shRNA was infused into the lateral ventricle 3 weeks before SAH induction. Neurological tests, immunofluorescence, DHE, TUNEL, Nissl staining, transmission electron microscopy (TEM), and Western blot were performed. RESULTS: The expression of CB1R, Nrf1, PINK1, Parkin, and LC3II increased and peaked at 24 h after SAH. ACEA treatment exhibited the antioxidative stress and antiapoptosis effects after SAH. In addition, ACEA treatment increased the expression of Nrf1, PINK1, Parkin, LC3II, and Bcl-xl but repressed the expression of Romo-1, Bax, and cleaved caspase-3. Moreover, the TEM results demonstrated that ACEA promoted the formation of mitophagosome and maintained the normal mitochondrial morphology of neurons. The protective effect of ACEA was reversed by AM251 and Nrf1 shRNA, respectively. CONCLUSIONS: This study demonstrated that ACEA alleviated oxidative stress and neurological dysfunction by promoting mitophagy after SAH, at least in part via the CB1R/Nrf1/PINK1 signaling pathway.

Metformin attenuates early brain injury after subarachnoid hemorrhage in rats via AMPK-dependent mitophagy.

Metformin is the most widely used drug to treat type 2 diabetes and its mitochondrial activity is through activation of adenosine monophosphate-activated protein kinase (AMPK). AMPK plays a dual regulatory role in mito-morphosis, controlling the phosphorylation and activation of dynamin-related protein 1 (DRP1) and mitofusin 2 (MFN2). The aim of this study was to investigate whether metformin could reduce early brain injury (EBI) after subarachnoid hemorrhage (SAH) by activating mitophagy and improving mitochondrial morphology through AMPK. This study used 308 male Sprague-Dawley rats. First, different metformin doses were injected intraperitoneally 30 min post-SAH. The dose that did not significantly alter blood glucose in the rats was selected for subsequent experiments. Before or after sacrificing rats, neurological function, brain water content, and blood-brain barrier (BBB) permeability were measured in each group. Transmission electron microscopy was used to observe the level of mitophagy and mito-morphology in each group. The expression of mitophagic and apoptotic proteins were investigated by immunofluorescence and western blot. Metformin at 20 mg/kg improved neurological function and attenuated brain edema and the disruption of BBB permeability 24 h after SAH. Metformin treatment after SAH promoted mitophagy in an AMPK-dependent manner. In addition to the effects on mitophagy, we also found that metformin alleviated oxidative stress and apoptosis after SAH in an AMPK-dependent manner. Lastly, metformin restored homeostasis between mitochondrial fusion and fission. Metformin attenuated EBI after SAH in rats through AMPK-dependent signaling. These protective effects might be achieved by regulating mitochondrial morphology and promoting mitophagy.

Self-supervised next view prediction for limited-angle optical projection tomography.

Optical projection tomography captures 2-D projections of rotating biological samples and computationally reconstructs 3-D structures from these projections, where hundreds of views with an angular range of π radian is desired for a reliable reconstruction. Limited-angle tomography tries to recover the structures of the sample using fewer angles of projections. However, the result is far from satisfactory due to the missing of wedge information. Here we introduce a novel view prediction technique, which is able to extending the angular range of captured views for the limited-angle tomography. Following a self-supervised technique that learns the relationship between the captured limited-angle views, unseen views can be computationally synthesized without any prior label data required. Combined with an optical tomography system, the proposed approach can robustly generate new projections of unknown biological samples and extends the angles of the projections from the original 60° to nearly 180°, thereby yielding high-quality 3-D reconstructions of samples even with highly incomplete measurement.

Inhibition of Ferroptosis Alleviates Early Brain Injury After Subarachnoid Hemorrhage In Vitro and In Vivo via Reduction of Lipid Peroxidation.

Subarachnoid hemorrhage (SAH) is a serious cerebrovascular disease with high mortality, and the mean age at morbidity is younger than in other types of stroke. Early brain injury (EBI) plays a key role in the poor prognoses of SAH. In EBI, multiple forms of cell death have been identified and well studied; however, the role of ferroptosis has not been elucidated. Hence, in this study, we developed an in vivo (SAH rat model) and in vitro model (SH-SY5Y oxyhemoglobin injury model) to understand the role of ferroptosis in EBI, then explored the protective mechanism of ferrostatin-1 (Fer-1). Firstly, we found that neurological scores, blood-brain barrier permeability, brain edema deteriorated after SAH in the in vivo model, cell viability was decreased after SAH in both cortex and SH-SY5Y cells. Further, iron content in cortex was increased after SAH, while transferrin receptor 1 and ferroportin (Fpn) were increased in oxyhemoglobin-treated in vitro model. Additionally, glutathione content and glutathione peroxidase 4 activity were reduced in SAH rats, and lipid peroxides were increased in the oxyhemoglobin-treated cells. Finally, administration of Fer-1 upregulated Fpn and decreased the iron content, then improved the lipid peroxidation and EBI. However, Fer-1 had no effect on the apoptosis. Our study indicated that the ferroptosis was involved in EBI of SAH, and the inhibitor Fer-1 provided neuroprotection against EBI by alleviating ferroptosis, the potential protective mechanism might be via suppressing lipid peroxidation.

Diagnostic and prognostic potential of circulating miRNAs for intracranial aneurysms.

Intracranial aneurysm (IA) is an abnormal focal dilation of an artery in the brain that results from a weakening of the inner muscular layer of a blood vessel wall. IAs represent the most common etiology of nontraumatic subarachnoid hemorrhage (SAH). Despite technological advances in the treatment and use of new diagnostic methods for IAs, they continue to pose a significant risk of mortality and disability. Thus, early recognition of IA with a high risk of rupture is crucial for the stratification of patients with such a formidable disease. MicroRNAs (miRNA) are endogenous noncoding RNAs of 18-22 nucleotides that regulate gene expression at the post-transcriptional level through interaction with 3'-untranslated regions (3'UTRs) of the target mRNAs. MiRNAs are involved in the pathogenesis of IAs, including in the mechanisms of formation, growth, and rupture. It is known that in many biological fluids of the human body, such as blood or cerebrospinal fluid (CSF), numerous miRNAs, called circulating miRNAs, have been detected. The expression profile of circulating miRNAs represents a certain part of the cells in which they are modified and secreted in accordance with the physiological or pathological conditions of these cells. Circulating miRNAs can be secreted from cells into human biological fluids in extracellular vesicles or can be bound to Ago2 protein, which makes them resistant to the effects of RNAse. Therefore, circulating miRNAs are considered as new potential biomarkers of interest in many diseases, including IA.

A CCD based machine vision system for real-time text detection.

Text detection and recognition is a hot topic in computer vision, which is considered to be the further development of the traditional optical character recognition (OCR) technology. With the rapid development of machine vision system and the wide application of deep learning algorithms, text recognition has achieved excellent performance. In contrast, detecting text block from complex natural scenes is still a challenging task. At present, many advanced natural scene text detection algorithms have been proposed, but most of them run slow due to the complexity of the detection pipeline and cannot be applied to industrial scenes. In this paper, we proposed a CCD based machine vision system for real-time text detection in invoice images. In this system, we applied optimizations from several aspects including the optical system, the hardware architecture, and the deep learning algorithm to improve the speed performance of the machine vision system. The experimental data confirms that the optimization methods can significantly improve the running speed of the machine vision system and make it meeting the real-time text detection requirements in industrial scenarios.

Protective effects of astaxanthin on subarachnoid hemorrhage-induced early brain injury: Reduction of cerebral vasospasm and improvement of neuron survival and mitochondrial function.

The purpose of this study was to evaluate the neuroprotective effects of astaxanthin on early brain injury (EBI) caused by subarachnoid hemorrhage (SAH) in rats and to explore possible molecular mechanisms. Experimental SAH model was introduced in adult male SD rats by injecting autologous arterial blood into the prechiasmatic cistern. Astaxanthin (75 mg/kg bodyweight) or olive oil was administered by oral gavage at 3 h after SAH. Our results showed that astaxanthin attenuated SAH-induced cerebral vasospasm and reduced neuronal apoptosis. Astaxanthin inhibited mitochondria-associated neuron apoptosis in the prefrontal cortex after SAH: increased mitochondrial membrane potential, decreased Bax/Bcl-2 ratio, inhibited cytochrome C release in cytoplasm, and suppressed caspase-3 enzyme activity. Furthermore, the cerebral expression levels of synaptic proteins (Synapsin-1, postsynaptic density-95 and growth-associated protein-43) and nerve growth and neuronal differentiation factors (brain-derived neurotropic factor and purine-rich binding protein-alpha) were reduced following SAH. Astaxanthin partly restored their expression. In conclusion, our current work demonstrates that astaxanthin attenuates SAH-induced EBI, possibly by improving neuronal survival and mitochondrial function.

Docosahexaenoic Acid Alleviates Oxidative Stress-Based Apoptosis Via Improving Mitochondrial Dynamics in Early Brain Injury After Subarachnoid Hemorrhage.

Mitochondrial dysfunction is considered a crucial therapeutic target for early brain injury following subarachnoid hemorrhage (SAH). Emerging evidence indicates that docosahexaenoic acid (DHA), an essential omega-3 fatty acid, protects mitochondria in various chronic diseases. This study aimed to investigate the neuroprotective effects of DHA on mitochondrial dynamic dysfunction after EBI using in vivo and in vitro approaches. For in vivo experiments, the rat endovascular perforation SAH model was performed, whereby DHA was administered intravenously 1 h after induction of SAH. Primary cultured neurons treated with oxyhemoglobin (OxyHb) for 24 h were used to mimic SAH in vitro. Our results demonstrated that DHA improved neurological deficits and reduced brain edema in rats with SAH, and attenuated OxyHb-induced neuronal death in primary cultured cells. DHA reduced the amount of reactive oxygen species-positive cells and improved cell viability when compared to the SAH + vehicle group in vitro. DHA attenuated malondialdehyde levels and superoxide dismutase stress, increased Bcl2 and Bcl-xl, and decreased Bax and cleaved caspase-3 in vivo. Additionally, DHA ameliorated mitochondrial dysfunction, upregulated the mitochondrial fusion-related protein Optic Atrophy 1, and downregulated the mitochondrial fission-related protein Dynamin-Related-Protein 1 (Drp1) and Serine 616 phosphorylated Drp1 after SAH both in vitro and in vivo. Taken together, our current study demonstrates that DHA might prevent oxidative stress-based apoptosis after SAH. The characterization of the underlying molecular mechanisms may further improve mitochondrial dynamics-related signaling pathways.