Search

Ferroptosis, a new mode of nonapoptotic cell death, is increasingly recognized as a new hope in overcoming resistance to chemotherapy in cancer. Both canonical and noncanonical pathways can trigger ferroptosis execution via an iron-dependent lethal lipid peroxidation manner. However, growing evidence has shown that some cancer cells can survive ferroptotic stress through metabolic remodeling as regards iron metabolism, anti-oxidative systems, and lipid metabolism. In addition to the well-known roles of the XC−/glutathione/glutathione peroxidase 4 (XC‐/GSH/GPX4) axis in blocking ferroptosis, several recently identified pathways, including the Mevalonate-ferroptosis suppressor protein 1 (MVA-FSP1) axis, the GTP cyclohydrolase 1-Tetrahydrobiopterin (GCH1-BH4) axis, the peroxisome-ether-phospholipid axis, the acyl-CoA synthetase long-chain family member 3-monounsaturated fatty acids (ACSL3-MUFA) axis, and the Liver kinase B1-AMP-activated protein kinase (LKB1-AMPK) axis, can negatively regulate susceptibility to ferroptosis. Prominin-2, a newly identified ferroptosis-modulating protein, also drives cancer cells to escape from ferroptosis induction. These findings collectively led to major challenges and opportunities in the development of novel therapies that target the ferroptosis resistance of cancer cells.SignificanceFerroptosis is a lethal consequence of accumulated lipid peroxidation catalyzed by ferrous iron and oxygen. This unique cell death process appears to involve many diseases, such as neurodegeneration, ischemia/reperfusion injury, kidney disease, and a druggable target in therapy-resistant cancers. There is great expectation of being able to exploit ferroptosis for the treatment of as yet incurable diseases. However, the state of ferroptosis susceptibility is linked to various regulation pathways. This perspective aims to integrate the current understanding of signaling mechanisms for ferroptotic defenses and facilitates movement toward novel cancer therapeutic strategies.

Heterogenous fluid shear stress is known to provide mechanical cues for cell adhesion and translocation. To assemble 3D microstructures using current fabrication methods in a single channel and recapitulate in vivo heterogenous fluid flow would require hours of fabrication and specialized equipment. Inspired by the traditional art form of inside painting, we developed a technique for 3D fabrication of micro-patterned flow channels and mixed in vivo fluid flow in a matter of minutes. We termed this technique Multiphoton Inner Laser Lithography (MILL). We further showed that when combined with adaptive optics, MILL is compatible with both flat and curved channel shapes. MILL recapitulated in vivo tissue topology and 3D fluid flow within tissue stroma (low fluid shear, 0 - 3.5 dynes/cm2) and blood vessel (high fluid shear, 0 - 80 dynes/cm2). We demonstrate fibroblast cell and platelets adhere and translocate differently between laminar flow patterns that are homogenous versus heterogeneous in real time. Parallel strips of MILL channels were assembled for simultaneous platelet function test to quantify the efficacy of an antithrombotic GPVI Fab (~2000 microthrombi per test). The MILL technique can be readily reproduced in vivo fluid flow in minutes and benefit preclinical screening of drug pharmacokinetics.

Commercial microscopy systems make use of tandem scanning i.e. either slow or fast scanning. We constructed, for the first time, an advanced control system capable of delivering a dynamic line scanning speed ranging from 2.7 kHz to 27 kHz and achieve variable frame rates from 5 Hz to 50 Hz (512 × 512). The dynamic scanning ability is digitally controlled by a new customized open-source software named PScan1.0. This permits manipulation of scanning rates either to gain higher fluorescence signal at slow frame rate without increasing laser power or increase frame rates to capture high speed events. By adjusting imaging speed from 40 Hz to 160 Hz, we capture a range of calcium waves and transient peaks from soma and dendrite of single fluorescence neuron (CAL-520AM). Motion artifacts arising from respiratory and cardiac motion in small animal imaging reduce quality of real-time images of single cells in-vivo. An image registration algorithm, integrated with PScan1.0, was shown to perform both real time and post-processed motion correction. The improvement is verified by quantification of blood flow rates. This work describes all the steps necessary to develop a high performance and flexible polygon-mirror based multiphoton microscope system for in-vivo biological imaging.

Removal of complex aberrations at millisecond time scales over millimeters in distance in multiphoton laser scanning microscopy limits the total spatiotemporal imaging throughput for deep tissue imaging. Using a single low resolution deformable mirror and time multiplexing (TM) adaptive optics, we demonstrate video rate aberration correction (5 ms update rate for a single wavefront mask) for a complex heterogeneous distribution of refractive index differences through a depth of up to 1.1 mm and an extended imaging FOV of up to 0.8 mm, with up to 167% recovery of fluorescence intensity 335 µm from the center of the FOV. The proposed approach, termed raster adaptive optics (RAO), integrates image-based aberration retrieval and video rate removal of arbitrarily defined regions of dominant, spatially varied wavefronts. The extended FOV was achieved by demonstrating rapid recovery of up to 50 distinct wavefront masks at 500 ms update rates that increased imaging throughput by 2.3-fold. Because RAO only requires a single deformable mirror with image-based aberration retrieval, it can be directly implemented on a standard laser scanning multiphoton microscope.

The plateau zokor (Myospalaxbaileyi) is a specialized subterranean rodent that lives on the Qinghai-Tibet Plateau, and has successfully adapted to hypoxic environment. Raised expression of vascular endothelial growth factor (VEGF) and enhanced microvessel density (MVD) in tissues enable subterranean rodents to adapt to hypoxic sealed burrows. However, the expression of VEGF is inhibited by decreases in oxygen content, which is different from what obtains in Sprague Dawley (SD)rats. Thromspondin-1(TSP-1) is the first endogenous angiogenesis inhibitor identified inp53 pathway. It has several domains that bind to different proteins which regulate cell-to-cell interactions, inhibit endothelial cell proliferation and induce endothelial cell apoptosis (anti-angiogenesis). In this study, we analyzed the coding region and the expression pattern of TSP-1 gene in plateau zokor under different oxygen partial pressures using bioinformatics and qRT-PCR, respectively. Our results showed that the base and amino acid homologies between plateau zokor and Northern Israeli blind subterranean mole rat (Nannospalaxgalili) were 95.08 and 97.61%, respectively. There were eight parallel evolution sites with Nannospalaxgalili. Evaluation by 'Sorting Tolerant From Intolerant' (SIFT) algorithm showed four sites with significant effects on the function of TSP-1. Three-dimensional (3D) structures revealed that Asp185 and Thr270 were located in the NH2 terminal domain, with Glu536 in the Type I repeat domain, and Thr1092 in the COOH terminal domain. Compared to SD rats, the polarities of these four mutation sites changed. The expression levels of TSP-1 in plateau zokor tissues increased significantly from 2 260 m(16.12kPa) to 3 300 m(14.13kPa), but there was no significant difference in TSP-1 expression in SD rats. In conclusion, due to long-term adaption to the hypoxic environment of sealed burrows, plateau zokor upregulates the expression of TSP-1 to effect anti-angiogenesis. Moreover, mutations in gene structure of TSP-1 may play an important role in inhibiting angiogenesis.

In this study, we introduce two key improvements that overcome limitations of existing polygon scanning microscopes while maintaining high spatial and temporal imaging resolution over large field of view (FOV). First, we proposed a simple and straightforward means to control the scanning angle of the polygon mirror to carry out photomanipulation without resorting to high speed optical modulators. Second, we devised a flexible data sampling method directly leading to higher image contrast by over 2-fold and digital images with 100 megapixels (10 240 × 10 240) per frame at 0.25 Hz. This generates sub-diffraction limited pixels (60 nm per pixels over the FOV of 512 μm) which increases the degrees of freedom to extract signals computationally. The unique combined optical and digital control recorded fine fluorescence recovery after localized photobleaching (r ~10 μm) within fluorescent giant unilamellar vesicles and micro-vascular dynamics after laser-induced injury during thrombus formation in vivo. These new improvements expand the quantitative biological-imaging capacity of any polygon scanning microscope system.

We propose and demonstrate a novel configuration for depolarized interferometric fiber-optic gyroscopes (IFOGs). This configuration utilizes optical compensation between two orthogonal polarizations for suppressing errors induced by polarization nonreciprocity. Theoretical analysis shows that it is a new approach different from conventional IFOGs where a polarizer is mandatory. An experimental demonstration of the proposed IFOG (2097-m coil, open-loop configuration) achieves a low bias drift of 0.016 °/h in detecting the Earth's rotation rate. Furthermore, this configuration requires no polarizer or any other polarization-maintaining device.

Optical compensation is studied for suppressing polarization nonreciprocity (PN) induced errors in interferometric fiber-optic gyroscopes (IFOG). In convention IFOGs, a polarizer is necessarily used, and only one polarization is used for interference in order to achieve low PN error. Differently, we propose a new approach for using two polarizations simultaneously in the IFOG. PN error can be effectively suppressing by optical compensation between the two detected signals. Both simulation and experiment are presented, which shows that PN errors are effectively reduced by optical compensation. This new approach paves the way for low drift IFOGs with no polarizer.

Interference Fiber Optic Gyroscope (IFOG) is the mainstream Interferometric Fiber Optic Gyroscope (IFOG) is the mainstream optic inertial sensor products of rotation measurement in nowadays. However, short time migration as well as long time bias had been impacting IFOG for the first day it invented. For a better operation of orthogonal demodulation algorithm, which we proposed before had demonstrated an ability of suppressing the noise in IFOG. This article firstly concerning about the initial phase in the orthogonal demodulation of IFOG. Through posteriori estimation we achieved the balance orthogonal demodulation. Secondly, we place the 2 orthogonal channel data obtained from the IFOG, as reference signal for each other into an adaptive filter module, based on the LMS principle, obtaining a real-time improvement of short time migration and long time stability.

A new implementation of frequency shifting for the delayed self-heterodyne interferometer (DSHI) is proposed in this paper. In order to avoid the costly and complicated acoustic-optic modulator to shift frequency in the DSHI, we propose that a phase modulator can be used instead. The alternative strategy simplifies the complexity of the DSHI setup, as well as reduces the modulation-induced noise by modulating the two arms of DSHI at the same time. Theoretical and experimental analysis show that such a strategy successfully fulfills the frequency shifting function for the DSHI and accurate measurement of a laser’s linewidth and lineshape is realized correspondingly.

For the first time, a polygon-mirror laser scanning microscope is engineered to provide rapid changes in the field of view to achieve vector scanning and also ultrafine pixel resolution (50 nm) without increasing the overall acquisition rate.

Multiphoton laser scanning microscopes exhibit highly localized nonlinear optical excitation and are powerful instruments for in-vivo deep tissue imaging. Customized multiphoton microscopy has a significantly superior performance for in-vivo imaging because of precise control over the scanning and detection system. To date, there have been several flexible software platforms catered to custom built microscopy systems i.e. ScanImage, HelioScan, MicroManager, that perform at imaging speeds of 30-100fps. In this paper, we describe a flexible software framework for high speed imaging systems capable of operating from 5 fps to 1600 fps. The software is based on the MATLAB image processing toolbox. It has the capability to communicate directly with a high performing imaging card (Matrox Solios eA/XA), thus retaining high speed acquisition. The program is also designed to communicate with LabVIEW and Fiji for instrument control and image processing. Pscan 1.0 can handle high imaging rates and contains sufficient flexibility for users to adapt to their high speed imaging systems.

Intravital multiphoton microscopy has emerged as a powerful technique to visualize cellular processes in-vivo. Real time processes revealed through live imaging provided many opportunities to capture cellular activities in living animals. The typical parameters that determine the performance of multiphoton microscopy are speed, field of view, 3D imaging and imaging depth; many of these are important to achieving data from in-vivo. Here, we provide a full exposition of the flexible polygon mirror based high speed laser scanning multiphoton imaging system, PCI-6110 card (National Instruments) and high speed analog frame grabber card (Matrox Solios eA/XA), which allows for rapid adjustments between frame rates i.e. 5 Hz to 50 Hz with 512 × 512 pixels. Furthermore, a motion correction algorithm is also used to mitigate motion artifacts. A customized control software called Pscan 1.0 is developed for the system. This is then followed by calibration of the imaging performance of the system and a series of quantitative in-vitro and in-vivo imaging in neuronal tissues and mice.

Conventional signal processing methods for improving the random walk coefficient and the bias stability of interferometric fiber-optic gyroscopes are usually implemented in one-dimension sequence. In this paper, as a comparison, we allocated synchronous adaptive filters with the calculations of correlations of multidimensional signals in the perspective of the signal subspace. First, two synchronous independent channels are obtained through quadrature demodulation. Next, synchronous adaptive filters were carried out in order to project the original channels to the high related error channels and the approximation channels. The error channel signals were then processed by principal component analysis for suppressing coherent noises. Finally, an optimal state estimation of these error channels and approximation channels based on the Kalman gain coefficient was operated. Experimental results show that this signal processing method improved the raw measurements’ variance from 0.0630 [(°/h)2] to 0.0103 [(°/h)2].

Sensing instrument noises and environmental perturbations deteriorated the performance of observation systems such as telescopes and microscopies. Here we present a rotation quadrature demodulation method to suppress those phenomena in an attitude controllable ground-base telescope.

While interferometric fiber optic gyroscopes (IFOGs) are used in the inertial guidance area as replacements for traditional spinning rotor gyroscopes, the presence of optical noise as well as cost of such systems demonstrate that IFOGs still have not been optimized for this purpose. This paper proposes a solution to these problems, describing the design details and features of an optimized prototype attitude control system that uses depolarized IFOGs in the gyros and mounts depolarizers simultaneously on the entrance and exit of the fiber loop. Preliminary tests of an attitude control system built using these IFOGs demonstrate that this relatively low-cost system achieved the objective of compensating for the earth's spin and thus could be deployed as a system for the stabilization of telescopes.

The bias stability and random walk coefficients (RWC) of interferometric fiber-optic gyroscopes (IFOGs) are directly affected by characteristic noises produced by optoelectronics interactions in optic sensors. This paper documents a novel demodulation method for square wave modulated IFOGs, a method capable of suppressing the white noise that results from optical intensity noises and circuit noises as well as shot noises. In addition, this paper provides a statistical analysis of IFOG signals. Through use of orthogonal harmonic demodulation followed by deployment of matched filters to detract the Sagnac phase from the IFOGs, these channels we then processed, using principle component analysis (PCA), to establish optimal independent synchronous quadrature signal channels. Finally a difference procedure was carried out for the outputs. Our results showed that an experimental sample of the proposed IFOG (1982 m coil under uncontrolled room temperature) achieved a real-time output variance improvement in detecting the Earth's rotation rate, which is well matched with theoretical calculations of its Cramèr-Rao bound (CRB).

We propose a novel method of quadrature demodulation with synchronous difference for suppressing noise in interferometric fiber-optic gyroscopes (IFOGs). For an IFOG with sine wave phase modulation, an in-phase result and a quadrature result are obtained simultaneously by coherent detection. Eigenfrequency modulation is used and a phase shift of 45° is set between the modulation signal and the reference signal, so that two results have the same expectation of amplitude but with opposite signs. A synchronous difference procedure is carried out for output, in which signals are added up and common noise between two results is eliminated. Theoretical analysis and experimental results show that both short term noise and long term instability of the IFOG are reduced by this method. In experimental comparison with the traditional demodulation method on the same IFOG with a 1982 m fiber coil, this method reduces the bias drift from 0.040°/h to 0.004°/h.

We demonstrate a new MEMS-Based Shadowless-illuminated variable-angle TIRF (SIVA-TIRF), which can realize two-plane, two-color TIRF imaging at the speed of 25Hz.

We propose a raster scanning adaptive optics method that uses digital image segmentation and a low-resolution deformable mirror with a maximum of 50 wavefront masks, which removes spatially varying aberrations (both sample and lens) across a field of view of 0.8 mm at 500 ms.