Label-free imaging of hemoglobin degradation and hemosiderin formation in brain tissues with femtosecond pump-probe microscopy

Effect of Egyptian spitting cobra Naja nubiae crude venom on immunogenic activity of rats

Snakes show defensive activities, often counting visual or auditory displays against an aggressor. The study observed what happens to rats administered subcutaneously sub-lethal doses of crude venom Naja nubiae. The pro-inflammatory cytokines, such as tumor necrosis alpha (TNF-α) and interleukin-6 (IL-6), as well as the anti-inflammatory cytokines such as interleukin-10 (IL-10), and inflammatory mediator's prostaglandin E-2 (PG-E2), were evaluated. Vascular permeability (VP) was employed to assess how leaky or permeable blood vessels are in various tissues and organs, including the rat peritoneal cavity and lymphoid organs. Lymphoid organs' histological alterations brought on by Nubiae venom. The study found that the two venom doses-1/4 and 1/2 LD50-induced high levels of inflammatory activity as evidenced by the production of inflammatory cytokines. These findings demonstrated that venom enhanced innate immunity through specifically increased T helper cells, IL-6, TNF-α, IL-10, and PG-E2. The results reveal whether the venom has an immunomodulatory effect and promotes inflammation. The data have a substantial impact on the development of new drugs and treatments for inflammatory conditions.

Imaging Ultrafast Dynamics of Pressure-Driven Phase Transitions in Black Phosphorus and Anomalous Coherent Phonon Softening

Applying high pressure to effectively modulate the electronic and lattice structures of materials could unravel various physical properties associated with phase transitions. In this work, high-pressure-compatible femtosecond pump-probe microscopy was constructed to study the pressure-dependent ultrafast dynamics in black phosphorus (BP) thin films. We observed pressure-driven evolution of the electronic topological transition and three structural phases as the pressure reached ∼22 GPa, which could be clearly differentiated in the transient absorption images containing spatially resolved ultrafast carrier and coherent phonon dynamics. Surprisingly, an anomalous coherent acoustic phonon mode with pressure softening behavior was observed within the range of ∼3-8 GPa, showing distinct laser power and time dependences. Density functional theory calculations show that this mode, identified as the shear mode along the armchair orientation, gains significant electron-phonon coupling strength from out-of-plane compression that leads to decreased phonon frequency. Our results provide insights into the structure evolution of BP with pressure and hold potential for applications in microelectromechanical devices.

The microRNA-211-5p/P2RX7/ERK/GPX4 axis regulates epilepsy-associated neuronal ferroptosis and oxidative stress

Ferroptosis is an iron-dependent cell death mechanism involving the accumulation of lipid peroxides. As a critical regulator, glutathione peroxidase 4 (GPX4) has been demonstrated to be downregulated in epilepsy. However, the mechanism of ferroptosis in epilepsy remains unclear. In this study, bioinformatics analysis, analysis of epilepsy patient blood samples and cell and mouse experiments revealed strong associations among epilepsy, ferroptosis, microRNA-211-5p and purinergic receptor P2X 7 (P2RX7). P2RX7 is a nonselective ligand-gated homotrimeric cation channel, and its activation mainly increases neuronal activity during epileptic seizures. In our study, the upregulation of P2RX7 in epilepsy was attributed to the downregulation of microRNA (miR)-211-5p. Furthermore, P2RX7 has been found to regulate GPX4/HO-1 by alleviating lipid peroxidation induced by suppression of the MAPK/ERK signaling pathway in murine models. The dynamic decrease in miR-211-5p expression induces hypersynchronization and both nonconvulsive and convulsive seizures, and forebrain miR-211-5p suppression exacerbates long-lasting pentylenetetrazole-induced seizures. Additionally, in this study, induction of miR-211-5p expression or genetic-silencing of P2RX7 significantly reduced the seizure score and duration in murine models through the abovementioned pathways. These results suggest that the miR-211-5p/P2RX7 axis is a novel target for suppressing both ferroptosis and epilepsy.

Precise diagnosis of breast phyllodes tumors using Raman spectroscopy: Biochemical fingerprint, tumor metabolism and possible mechanism

BACKGROUND

Breast fibroadenomas and phyllodes tumors are both fibroepithelial tumors with comparable histological characteristics. However, rapid and precise differential diagnosis is a tough point in clinical pathology. Given the tendency of phyllodes tumors to recur, the difficulty in differential diagnosis with fibroadenomas leads to the difficulty in optimal management for these patients.

METHOD

In this study, we used Raman spectroscopy to differentiate phyllodes tumors from breast fibroadenomas based on the biochemical and metabolic composition and develop a classification model. The model was validated by 5-fold cross-validation in the training set and tested in an independent test set. The potential metabolic differences between the two types of tumors observed in Raman spectroscopy were confirmed by targeted metabolomic analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

A total of 204 patients with formalin-fixed paraffin-embedded (FFPE) tissue samples, including 100 fibroadenomas and 104 phyllodes tumors were recruited from April 2014 to August 2021. All patients were randomly divided into the training cohort (n = 153) and the test cohort (n = 51). The Raman classification model could differentiate phyllodes tumor versus fibroadenoma with cross-validation accuracy, sensitivity, precision, and area under curve (AUC) of 85.58 % ± 1.77 %, 83.82 % ± 1.01 %, 87.65 % ± 4.22 %, and 93.18 % ± 1.98 %, respectively. When tested in the independent test set, it performed well with the test accuracy, sensitivity, specificity, and AUC of 83.50 %, 86.54 %, 80.39 %, and 90.71 %. Furthermore, the AUC was significantly higher for the Raman model than that for ultrasound (P = 0.0017) and frozen section diagnosis (P < 0.0001). When it came to much more difficult diagnosis between fibroadenoma and benign or small-size phyllodes tumor for pathological examination, the Raman model was capable of differentiating with AUC up to 97.45 % and 95.61 %, respectively. On the other hand, targeted metabolomic analysis, based on fresh-frozen tissue samples, confirmed the differential metabolites (including thymine, dihydrothymine, trans-4-hydroxy-l-proline, etc.) identified from Raman spectra between phyllodes tumor and fibroadenoma.

SIGNIFICANCE AND NOVELTY

In this study, we obtained the molecular information map of breast phyllodes tumors provided by Raman spectroscopy for the first time. We identified a novel Raman fingerprint signature with the potential to precisely characterize and distinguish phyllodes tumors from fibroadenoma as a quick and accurate diagnostic tool. Raman spectroscopy is expected to further guide the precise diagnosis and optimal treatment of breast fibroepithelial tumors in the future.

Multifunctional Carbon Quantum Dots: Iron Clearance and Antioxidation for Neuroprotection in Intracerebral Hemorrhage Mice

Iron overload and oxidative stress are pivotal in the pathogenesis of brain injury secondary to intracerebral hemorrhage (ICH). There is a compelling need for agents that can chelate iron and scavenge free radicals, particularly those that demonstrate substantial brain penetration, to mitigate ICH-related damage. In this study, we have engineered an amine-functionalized aspirin-derived carbon quantum dot (NACQD) with a nominal diameter of 6-13 nm. The NACQD possesses robust iron-binding and antioxidative capacities. Through intrathecal administration, NACQD therapy substantially reduced iron deposition and oxidative stress in brain tissue, alleviated meningeal inflammatory responses, and improved the recovery of neurological function in a murine ICH model. As a proof of concept, the intrathecal injection of NACQD is a promising therapeutic strategy to ameliorate the ICH injury.

Research progress on correlations between trace element levels and epilepsy

Research investigating the correlation between human trace element levels and disease alterations is growing. Epilepsy, a common nervous system disease, has also been found to be closely related to abnormal levels of trace elements. Studies continue to explore mechanisms of various trace elements involved in epileptic seizures through experimental animal models of epilepsy. Thus, we reviewed the research progress on the correlation between trace element levels and epilepsy in recent years and found that the trace elements most closely related to epilepsy are mainly metal ions such as selenium, iron, copper, zinc, and manganese. These results indicate that the changes in some trace elements are closely related to the increase in epilepsy susceptibility. In addition, after treatment with drugs and a ketogenic diet, the concentration of trace elements in the serum of patients with epilepsy changes. In other words, the abnormality of trace element concentrations is of great significance in the occurrence and development of epilepsy. This article is a literature update on the potential role of trace element imbalance in the development of epilepsy, providing new references for the subsequent prevention and treatment of epilepsy.

Deciphering the role of metal and non-metals in the treatment of epilepsy

Metals and non-metals have known to play a significant role in various physiological roles in the body including the central nervous system (CNS). The alterations in their concentration in the CNS leads to abnormalities in the normal functions which may lead to various neurological conditions including epilepsy. Manganese is a cofactor required for antioxidant enzymes such as Superoxide dismutase, Glutamine synthetase, etc. The accumulation of iron leads to formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) which have the potential to cause ferroptosis, one of the reasons for epileptogenesis. Zinc has biphasic response, both neurotoxic and neuroprotective, based on concentration levels in the CNS. Selenium is a main element for selenoproteins which is responsible for the regulation of oxidative state and antioxidant defence mechanism. The reduction in the phosphorous levels in the CNS is widely observed after generalised tonic clonic seizures (GTC), which can be a potential diagnostic biomarker. Copper acts in the CNS in an identical manner, i.e., by blocking both AMPA mediated and GABA mediated neuronal transmission. Magnesium blocks calcium channels in the NMDA receptor and prevents glutamatergic transmission, thus inhibiting excitotoxicity. Lithium acts as a proconvulsive agent and is used in combination with pilocarpine to induce seizures. The identified potential of metals and non-metals in epilepsy can be utilised in order to devise new adjuvant therapies for the management of epilepsy. The article summaries in depth the role of metals and non-metals in the treatment of epilepsy supported with special paragraph on author perspective on to the topic. Furthermore, an update of preclinical and clinical evidences are discussed in the review to give evidence on metal and non-metal based therapies in epilepsy.

Remote control of transgene expression using noninvasive near-infrared irradiation

This study investigated whether noninvasive near-infrared (NIR) energy could be transduced into heat in deep-seated organs in which adenovirus type-5 vectors tend to accumulate, thereby activating heat shock protein (HSP) promoter-mediated transgene expression, without local administration of photothermal agents. NIR irradiation of the subdiaphragmatic and left dorsocranial part of the abdominal cavity of adult immunocompetent C3H/HeNRj mice with an 808-nm laser effectively increased the temperature of the irradiated regions of the liver and spleen, respectively, resulting in the accumulation of the heat-inducible HSP70 protein. Spatial control of transgene expression was achieved in the NIR-irradiated regions of the mice administered an adenoviral vector carrying a firefly luciferase (fLuc) coding sequence controlled by a human HSP70B promoter, as assessed by bioluminescence and immunohistochemistry analyses. Levels of reporter gene expression were modulated by controlling NIR power density. Spatial control of transgene expression through NIR-focused activation of the HSP70B promoter, as well as temporal regulation by administering rapamycin was achieved in the spleens of mice inoculated with an adenoviral vector encoding a rapamycin-dependent transactivator driven by the HSP70B promoter and an adenoviral vector carrying a fLuc coding sequence controlled by the rapamycin-activated transactivator. Mice that were administered rapamycin and exposed to NIR light expressed fLuc activity in the splenic region, whereas no activity was detected in mice that were only administered rapamycin or vehicle or only NIR-irradiated. Thus, in the absence of any exogenously supplied photothermal material, remote control of heat-induced transgene expression can be achieved in the liver and spleen by means of noninvasive NIR irradiation.

Label-Free Imaging of Humic Substance Bioaccumulation by Pump-Probe Microscopy

Humic substances (HS) are the most abundant forms of natural organic matter on the earth surface. Comprised of decomposed plant and animal materials rich in carbon, oxygen, hydrogen, nitrogen, and sulfur complexes, HS facilitate global carbon and nitrogen cycling and the transport of anthropogenic contaminants. While it is known that HS also interact with organisms at different trophic levels to produce beneficial and harmful effects whether HS exert these biological effects through accumulation remains unknown. Current radiolabeling techniques, which only detect the amount of accumulated radiolabels, cannot visualize the transport and accumulation behavior of HS. Here, using a label-free method based on pump-probe microscopy, we show HS entered the protozoan Tetrahymena thermophila, zebrafish embryos, and human cells and exerted direct effects on these organisms. HS accumulated in the nucleus of T. thermophila, chorion pore canals of zebrafish embryos, and nucleus of intestinal and lung cells in a concentration- and time-dependent way. Epigenetic and transcriptomics assays show HS altered chromatin accessibility and gene transcription in T. thermophila. In zebrafish larvae, HS induced neurotoxicity, altering spontaneous muscle contraction and locomotor activity. Detailed images showing HS accumulation in our study reveal new insights on the ecological and environmental behavior of HS.

Enhanced sciatic nerve regeneration by relieving iron-overloading and organelle stress with the nanofibrous P(MMD-co-LA)/DFO conduits

Wallerian degeneration after peripheral nerve injury (PNI), that is, the autonomous degeneration of distal axons, leads to an imbalance of iron homeostasis and easily induces oxidative stress caused by iron overload. Inspired by the process of nerve degeneration and regeneration, the design of a functional electrospinning scaffold with iron chelating ability exhibited the importance of reconstructing a suitable microenvironment. Here, an electrospinning scaffold based on deferoxamine and poly(3(S)-methyl-morpholine-2,5-dione-co-lactone) (PDPLA/DFO) was constructed. This work aims to explore the promotion of nerve regeneration by the physiological regulation of the scaffold. In vitro, PDPLA/DFO films mitigated the reduction of glutathione and the inactivation of Glutathione peroxidase 4 caused by iron overload. In addition, they decreased reactive oxygen species, relieve the stress of the endoplasmic reticulum and mitochondria, and reduce cell apoptosis. In vivo, PDPLA/DFO conduits constructed the anti-inflammatory microenvironment and promoted cell survival by alleviating iron overload and organelle stress. In conclusion, PDPLA/DFO guidance conduits targeted the distal iron overload and promoted nerve regeneration. It provides novel ideas for designing nerve conduits targeting the distal microenvironment.

Bioactive nutraceutical ligands and their efficiency to chelate elemental iron of varying dynamic oxidation states to mitigate associated clinical conditions

The natural bioactive or nutraceuticals exhibit several health benefits, including anti-inflammatory, anti-cancer, metal chelation, antiviral, and antimicrobial activity. The inherent limitation of nutraceuticals or bioactive ligand(s) in terms of poor pharmacokinetic and other physicochemical properties affects their overall therapeutic efficiency. The excess of iron in the physiological compartments and its varying dynamic oxidation state [Fe(II) and Fe(III)] precipitates various clinical conditions such as non-transferrin bound iron (NTBI), labile iron pool (LIP), ferroptosis, cancer, etc. Though several natural bioactive ligands are proposed to chelate iron, the efficiency of bioactive ligands is limited due to poor bioavailability, denticity, and other related physicochemical properties. The present review provides insight into the relevance of studying the dynamic oxidation state of iron(II) and iron(III) in the physiological compartments and its clinical significance for selecting diagnostics and therapeutic regimes. We suggested a three-pronged approach, i.e., diagnosis, selection of therapeutic regime (natural bioactive), and integration of novel drug delivery systems (NDDS) or nanotechnology-based principles. This systematic approach improves the overall therapeutic efficiency of natural iron chelators to manage iron overload-related clinical conditions.

Label-Free Delineation of Human Uveal Melanoma Infiltration With Pump–Probe Microscopy

Uveal melanoma (UM) is the most frequent primary intraocular malignancy in adults, characterized by melanin depositions in melanocytes located in the uveal tract in the eyes. Differentiation of melanin species (eumelanin and pheomelanin) is crucial in the diagnosis and management of UM, yet it remains inaccessible for conventional histology. Here, we report that femtosecond time-resolved pump-probe microscopy could provide label-free and chemical-specific detection of melanin species in human UM based on their distinct transient relaxation dynamics at the subpicosecond timescale. The method is capable of delineating the interface between melanoma and paracancerous regions on various tissue conditions, including frozen sections, paraffin sections, and fresh tissues. Moreover, transcriptome sequencing was conducted to confirm the active eumelanin synthesis in UM. Our results may hold potential for sensitive detection of tumor boundaries and biomedical research on melanin metabolism in UM.

Pathogenesis of seizures and epilepsy after stroke

Stroke is the most frequent cause of secondary epilepsy in the elderly. The incidence of cerebral stroke is increasing with the extension of life expectancy, and the prevalence of post-stroke epilepsy (PSE) is rising. There are various seizure types after stroke, and the occurrence of epilepsy is closely related to the type and location of stroke. Moreover, the clinical treatment of post-stroke epilepsy is difficult, which increases the risk of disability and death, and affects the prognosis and quality of life of patients. Now seizure and epilepsy after stroke is more and more get the attention of the medical profession, has been more and more researchers have devoted to seizures after stroke and PSE clinical and basic research, and hope to get a scientific and unified guideline, to give timely and effective treatment, but the exact pathophysiologic mechanism has not yet formed a unified conclusion. It has been found that ion channels, neurotransmitters, proliferation of glial cells, genetics and other factors are involved in the occurrence and development of PSE. In this review, we discuss the pathogenesis of early-onset epileptic seizures and late-onset epilepsy after stroke, in order to provide a basis for clinicians to understand the disease, and expect to provide ideas for future exploration.

Microcalcification-Based Tumor Malignancy Evaluation in Fresh Breast Biopsies with Hyperspectral Stimulated Raman Scattering

Precise evaluation of breast tumor malignancy based on tissue calcifications has important practical value in the disease diagnosis, as well as the understanding of tumor development. Traditional X-ray mammography provides the overall morphologies of the calcifications but lacks intrinsic chemical information. In contrast, spontaneous Raman spectroscopy offers detailed chemical analysis but lacks the spatial profiles. Here, we applied hyperspectral stimulated Raman scattering (SRS) microscopy to extract both the chemical and morphological features of the microcalcifications, based on the spectral and spatial domain analysis. A total of 211 calcification sites from 23 patients were imaged with SRS, and the results were analyzed with a support vector machine (SVM) based classification algorithm. With optimized combinations of chemical and geometrical features of microcalcifications, we were able to reach a precision of 98.21% and recall of 100.00% for classifying benign and malignant cases, significantly improved from the pure spectroscopy or imaging based methods. Our findings may provide a rapid means to accurately evaluate breast tumor malignancy based on fresh tissue biopsies.

Iron Metabolism and Ferroptosis in Epilepsy

Epilepsy is a disease characterized by recurrent, episodic, and transient central nervous system (CNS) dysfunction resulting from an excessive synchronous discharge of brain neurons. It is characterized by diverse etiology, complex pathogenesis, and difficult treatment. In addition, most epileptic patients exhibit social cognitive impairment and psychological impairment. Iron is an essential trace element for human growth and development and is also involved in a variety of redox reactions in organisms. However, abnormal iron metabolism is associated with several neurological disorders, including hemorrhagic post-stroke epilepsy and post-traumatic epilepsy (PTE). Moreover, ferroptosis is also considered a new form of regulation of cell death, which is attributed to severe lipid peroxidation caused by the production of reactive oxygen species (ROS) and iron overload found in various neurological diseases, including epilepsy. Therefore, this review summarizes the study on iron metabolism and ferroptosis in epilepsy, in order to elucidate the correlation between iron and epilepsy. It also provides a novel method for the treatment, prevention, and research of epilepsy, to control epileptic seizures and reduce nerve injury after the epileptic seizure.

Direct Quantification of Single Red Blood Cell Hemoglobin Concentration with Multiphoton Microscopy

Blood disorders, diseases, and infections often affect the shape, number, and content of red blood cells (RBCs) dramatically. To combat these pathologies, many therapies target RBCs and their contents directly. Mean corpuscular hemoglobin concentration (MCHC) is an important pathological metric in both identification and treatment. However, current methods for RBC analysis and MCHC quantification rely on bulk measurements. Single RBC measurements could provide necessary insight into the heterogeneity of RBC health and improve therapeutic efficacy. In this study, we present a novel multimodal multiphoton approach for quantifying hemoglobin concentration at single RBC resolution. We achieve this by collecting two images simultaneously that allows us to excite water with stimulated Raman scattering and hemoglobin with transient absorption. This multimodal imaging is enabled by a newly designed orthogonal modulation theme for dual-channel lock-in detection. By leveraging water as an internal standard, we quantify MCHC of healthy RBCs and RBCs infected with Plasmodium yoelii, a commonly studied rodent parasite model.

Transient absorption microscopy: Technological innovations and applications in materials science and life science

Transient absorption (TA) spectroscopy has been extensively used in the study of excited state dynamics of various materials and molecules. The transition from TA spectroscopy to TA microscopy, which enables the space-resolved measurement of TA, is opening new investigations toward a more complete picture of excited state dynamics in functional materials, as well as the mapping of crucial biopigments for precision diagnosis. Here, we review the recent instrumental advancement that is pushing the limit of spatial resolution, detection sensitivity, and imaging speed. We further highlight the emerging application in materials science and life science.

Spatial light-modulated stimulated Raman scattering (SLM-SRS) microscopy for rapid multiplexed vibrational imaging

High speed imaging is pre-requisite for monitoring of dynamic processes in biological events. Here we report the development of a unique spatial light-modulated stimulated Raman scattering (SLM-SRS) microscopy that tailors the broadband excitation beam with sparse-sampling masks designed for rapid multiplexed vibrational imaging to monitor real-time cancer treatment effects and in vivo transport of drug solvent.

Methods: We design an optimal mask pattern that enables selection of predominant windows in SRS spectrum for collective excitation at the highest possible peak power, thus providing an improved signal-to-noise ratio (SNR) without compromise of chemical specificity. The mask pattern generated is applied to the broad excitation beam using a flexible spatial light modulator. The SLM module further offers complementary function whereby rapid scanning of SRS spectrum can be facilitated prior to the mask generation, thereby making the SLM-SRS system a stand-alone imaging platform.

Results: We demonstrate that SLM-SRS microscopy permits rapid multiplexed SRS imaging of polystyrene and polymethyl methacrylate beads in Brownian motion in dimethyl sulfoxide (DMSO) at 70 ms intervals without motion artiacts. We further apply SLM-SRS to monitor the therapeautic effect of mild alkaline solution on cancer cells, which shows immediate apoptotic response. Finally, we visualize in vivo penetration of DMSO into the plant tissue and evaluate acute toxicity of DMSO on cellulose and proteins within the tissue.

Conclusion: We develop novel SLM-SRS microscopy and affirm its broad applicability for rapid monitoring of dynamic biological processes at the subcellular and molecular level.

In Vitro Quantification of Single Red Blood Cell Oxygen Saturation by Femtosecond Transient Absorption Microscopy

Hemoglobin, the oxygen carrying protein, ferries nearly all bodily oxygen from the lungs to cells and tissues in need. Blood oxygen saturation (sO₂) thus plays an important role in maintaining energy homeostasis throughout the body. Clinical and research tools have been developed to monitor sO₂ at a wide range of temporal and spatial scales. However, real-time quantification of sO₂ at single red blood cell (RBC) resolution remains challenging. Such capability is critically important to study energy metabolism in heterogeneous tissues including brain and tumor tissue. In this work, we develop a ratiometric transient absorption microscopy technique to image hemoglobin sO₂. By exploiting differences in transient lifetime kinetics between  oxyhemoglobin and deoxyhemoglobin, we directly quantified the sO₂ of single RBCs in real-time without the need for injection of exogenous agents. This simple and high-speed nonlinear optical imaging technique is well suited for in vitro and in vivo quantification of sO₂.