Signal Intensity Enhancement Research Articles

Co-encapsulation of antimalarial drug and SPIO in glucose-conjugated polymeric micelles against parasite-infected erythrocytes

Malaria, a life-threatening infectious disease transmitted through bites of Anopheles mosquitoes, remains a major global health challenge. The erythrocytic stage of malaria, where the parasite undergoes multiplication within red blood cells, is crucial for disease progression. Targeting this stage is essential for effective treatment and eradication of the parasite. However, the emergence of drug resistance highlights the need for innovative therapeutic approaches. Furthermore, accurate detection and tracking of parasites are imperative for confirming complete parasite eradication. Enhancing drug efficacy and specifically targeting molecular entities are key strategies to address this challenge. To combat the disease, a drug delivery system was developed to encapsulate the drug along with contrast agents. This system was conjugated with glucose to target both new permeable pathways (NPPs) and the Plasmodium falciparum hexose transporter (PfHT). In this study, glucose-conjugated polymeric micelles containing superparamagnetic ironoxide (SPIO) nanoparticles and quinine were synthesized and characterized. These micelles demonstrated hemocompatibility and exhibited superior drug release profiles under acidic conditions mimicking the parasite's environment. In vitro studies on infected red blood cells (RBCs) revealed targeted micelles enhanced antimalarial activity compared to non-targeted micelles and free drug. Additionally, targeted micelles exhibited the highest fluorescence signal intensity and MRI contrast enhancement. Based on these results, glucose/quinine/SPIO micelles hold significant promise for tracking and treatment functions in malaria, offering precise detection and targeted drug delivery to eradicate the parasite effectively.

Radiologic Clue to Cavernous Sinus Hemangioma Diagnosis

We describe a case of a 57-year-old woman presenting initially with diplopia and later developing retro-orbital and retro-auricular pain. Examination showed right abducens nerve palsy and subsequent right trigeminal nerve hyperesthesia. Neuroimaging revealed a well-defined mass confined to right cavernous sinus, with high T2 signal intensity and homogeneous enhancement on post-gadolinium T1WI. A meningioma was initially considered as the most likely diagnosis. The lesion grew over months, extending to the Meckel's cave and pituitary fossa. Dynamic T1WI revealed striking and progressive centripetal enhancement, leading to a revised diagnosis of cavernous sinus hemangioma (CSH). CSH is a rare benign extra-axial tumor, highly vascularized, frequently misdiagnosed as meningioma or schwannoma. The combination of very high T2 signal intensity and progressive centripetal contrast enhancement highly suggest CSH diagnosis. Given the significant risk of bleeding and mortality associated with surgical intervention, it is crucial to recognize CSH preoperatively to plan a meticulous surgical approach.

Photoacoustic spectroscopy of layered crystals: An enhancement of the photoacoustic signal and its analysis from the perspective of heat generation

Photoacoustic spectroscopy is a powerful tool for investigating semiconductors and determining some of their basic properties. However, generating a signal that is large enough for the investigated samples is still challenging. To address this, the focus is on enhancing photoacoustic (PA) signal intensity in a non-complex way, which does not require changing any part of an experimental setup. The PA signal intensity enhancement is mainly achieved by manipulating the sample volume and its surroundings. MoS2, a layered material that belongs to the van der Waals crystals was selected due to ease of exfoliation to the proper thickness. A reduction in MoS2 thickness from 112 to 7 µm, resulted in enhancement of the PA signal by a factor of ∼50. A simple model has been proposed to describe the results based on thermal processes. Additionally, a method to determine the energy gap in transition metal dichalcogenides from PA measurements is presented.

CT and MRI features of adrenal hemangioma: A study of 21 cases from two centers

PurposeTo retrospectively analyze the CT and MR imaging presentations of adrenal hemangioma (AH) and to strengthen the recognition for such tumors. Materials and methodsThis retrospective study enrolled 21 patients with 22 lesions histologically proven AH from two centers between October 2010 and November 2023. The clinical presentation and preoperative diagnosis were recorded. Two radiologists reviewed the CT and MR imaging features in consensus, including number, size, shape, boundary, attenuation, signal intensity, and dynamic enhancement pattern. ResultsThe study included nine men and twelve women (mean age 55.6 ± 12.5 years, range, 35–77 years) without hormone production. AH was unilateral in 19 cases, bilateral in 2 cases. The maximum diameter was more than 3 cm in 19/22(86 %). AHs had oval (10/22,45 %), round (5/22, 23 %), or (7/22, 32 %) multilocular shape, and well-defined boundary (18/22,82 %). On unenhanced CT, 11/20 (55 %) displayed peripheral iso-density and central hypo-intensity, 3/20 (15 %) heterogeneously hyper-density, 6/20 (30 %) hypodensity, and 14/20 (70 %) contained speckled calcification. On T2-weighted images, 7/12 (58 %) exhibited nodular hyper-intensity peripherally, markedly hyper-intensity centrally, and hypo-intense fibrotic scar in between, 5/12 (42 %) hyperintensity. On T1-weighted images, 6/12 (50 %) displayed center hyper-intensity surrounded by peripheral hypo-intensity,5/12 hypo-intensity, 1/11 (9 %) hyperintensity. On DWI, 7/12 (58 %) demonstrated peripheral hyper-intensity and central hypo-intensity, 5/12 (42 %) hyper-intensity. CT and MR imaging findings were suggestive of cystic change and necrosis (19/22,86 %, 4 cystic tumors), hemorrhage (15/22,68 %), fat (7/22, 33 %) within the tumors. CT and MR enhanced images showed peripheral nodular enhancement with (3/22,14 %) or without (13/22, 59 %) delayed central filling, nodular peripheral and center enhancement with progressive partial fill-in (2/22,9%), capsular and/or septal mild enhancement (4/22, 18 %), and capsule (16/22,73 %). The solid part was significantly enhanced, similar to the abdominal aorta (AA) with no statistical difference between the two (P > 0.05). ConclusionsSmall AHs (<3cm) have the typical imaging features of hemangioma. The imaging findings of large AHs were various, the combination of T2-hyperintense signal with inner hypo-intense fibrotic scar, speckled calcification, central extensive necrosis and hemorrhage, and nodular peripheral enhancement with persistently slight further contrast accumulation may contribute to suggest the possibility. Cystic AH should be considered as a differential diagnosis for cystic adrenal masses.

An Efficient Fluorescent Chemosensing Probe for Total Determination and Speciation of Ultra-Trace Levels of Mercury (II) Species in Water.

The current study reports a novel fluorescent chemosensor based on the tagging agent 4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein (Rose Bengal, RB) for detection of trace levels of Hg2+in environmental water. The established probe has been based upon liquid-liquid extraction (LLE) of the developed ternary complex ion associate {[Hg (bpy)2]2+.[RB]2-} of Hg2+ -2,2- bipyridyl complex [Hg (bpy)2]2+ and RB at pH 9.0 onto chloroform and measuring the resulting fluorescence enhancement signal intensity at λex/em = 570/ (580-600) nm. The limits of detection (LOD) and quantification (LOQ) of for Hg2+ was calculated to be 6.06 and 20 nM with a linear dynamic range (LDR) of 0.02-20µM, respectively. The stability constant, stoichiometry, chemical equilibria, and the thermodynamic parameters (ΔH, ΔS, and ΔG) of the developed ion associate were evaluated and assigned. Student's t and F tests at 95% confidence were fruitfully used for validation of the proposed methodology for Hg2+ detection in water samples with the aid of inductively coupled plasma-optical emission spectrometry (ICP-OES). The established strategy was successfully applied for detection of trace levels of Hg2+ in water samples with acceptable results. The proposed probe was satisfactorily applied for total determination and speciation of Hg in various water samples. Integrating the functional chelating agent onto associate formation to improve the selectivity and sensing properties of the LLE combining sensing probe towards target analyte in water represent the main interest.

An Effective Liposome-Based Nanodelivery System for Naphthalene Derivative Polyamines with Antitumor Activity.

This study focuses on the development of a novel liposome-based nanodelivery system designed to encapsulate polyamine-1, a compound with potential anti-tumor properties. The main objective of this work was to enhance the therapeutic and imaging potential of polyamine-1 by incorporating it into liposome-based nanoparticles, which were functionalized with a gadolinium complex for imaging purposes and a fluorescent phospholipid for tracking applications. These nanoparticles were characterized by measuring their size, shape, polydispersity index, zeta potential and encapsulation efficiency. In vitro experiments were conducted to evaluate the antitumor activity, specifically determining the cytotoxicity of both free and encapsulated polyamine-1 in cancerous and non-cancerous cell lines. Additionally, the study shows the enhanced signal intensity of gadolinium-loaded liposomes by T1-weighted MRI, highlighting their imaging potential. The experimental results suggest that this liposome-based nanodelivery system not only has therapeutic potential in targeted cancer therapy but also could be advantageous for diagnostic imaging, particularly in MRI applications.

A New approach for simultaneous detection and photocatalytic degradation of imidacloprid and dinotefuran in water using terbium-based fluorometry and mixed-phase TiO2

This study explores a novel method for detecting neonicotinoid insecticides, imidacloprid (IMD) and dinotefuran (DNT), in water using terbium (Tb3+) ions photo probe. The optimal excitation and emission wavelengths for Tb3+ luminescence were identified at 310 nm and 545 nm, respectively. The influence of pH and solvent on Tb-complex fluorescence was investigated. Results indicate a significant enhancement of luminescence intensity at pH 6 for IMD in DMF and pH 7.0 for DNT in DMSO. The fluorescence intensity exhibited a linear relationship with IMD and DNT concentrations ranging from 0.1 to 20 µg/mL (R2 > 0.99). Limits of quantitation (LOQ) were determined as 0.1 µg/mL for IMD and 0.05 µg/mL for DNT. This newly developed photo probe demonstrates the potential for monitoring photolysis and photocatalytic degradation of these neonicotinoids using TiO2 as a catalyst under controlled photoreactor conditions. The method offers a promising alternative for rapidly and sensitively detecting these prevalent insecticides in water samples.

Selective Detection of Divalent Cations (Cu2+, Zn2+, Pb2+) and Anions (SO42-, S2-, CO32-) Using a pH-Sensitive Multi-functional Schiff Base inNeutralMedium.

A new Schiff base-based multi-cation/anion probe (L) has been synthesized and characterized using HR-MS, FT-IR, 1H, and 13C NMR techniques. The Schiff base motif provides specific binding sites that detect cations and anions by generating distinct optical output signals upon interaction. A noticeable color change of the probe solution was observed from pale yellow to various shades of yellow upon adding cations such as Cu2+, Zn2+, and Pb2+ and anions such as CO32⁻, S2⁻, and SO42⁻. This color change results from forming complexes like M3L2 with metal ions. Whereas origin of color in presence of anion were attributed due to the deprotonation of acidic proton in the ligand. Moreover, the complexes formed by Zn2+, S2/CO32⁻ ion with L are fluorescent, enabling the detection of Cu2+ and SO42⁻ using the Stern-Volmer plot, with a limit of detection (LODs) of 8.48µM and 10.47µM, respectively. Additionally, increasing the pH of the probe solution above 8 reveals a significant enhancement of fluorescence intensity due to the deprotonation of phenolic -OH and amide -NH in the presence of hydroxide ions. This emission in the basic medium is quenched by Cu2+ ions and restored when Cu2+ is complexed with EDTA. A logic gate has also been constructed for understanding the TURN-OFF-TURN-ON mechanism involving Cu2+ ions and EDTA. Overall, the versatile performance of a single probe L opens up new possibilities as a multifunctional sensor, making it highly suitable for practical applications.

Expression and immobilization of novel N-glycan-binding protein for highly efficient purification and enrichment of N-glycans, N-glycopeptides, and N-glycoproteins.

Comprehensive and selective enrichment of N-glycans, N-glycopeptides, and N-glycoproteins prior to analysis is of great significance in N-glycomics research, reducing sample complexity, removing impurity interference, increasing sample abundance and enhancing signal intensity. However, only an Fbs1 (F-box protein that recognizes sugar chain 1) GYR variant (Fg) can enrich these N-glycomolecules solely due to its substantial binding affinity for the core pentasaccharide motif of N-glycans. Stationary phase separation is commonly used to enrich N-glycomolecules efficiently. Herein, DNA encoding the Fg was cloned into pGEX-4T-1, and the protein was expressed with a GST tag, which facilitates the convenient and efficient immobilization of recombinant GST-tagged Fg to GSH agarose resin. The yield of the GST-tagged Fg reached to 0.05 g/L after optimization of the induction condition, and the purified protein exhibited good identification ability and excellent stability for months. In particular, the immobilized GST-tagged Fg can enrich N-glycans released byPNGase Fand capture derivatized N-glycans possessing an intact terminal N-acetyl glucosamine (GlcNAc). Validation of immobilized GST-tagged Fg with standard N-glycopeptides and N-glycoproteins revealed its high loading capacity, sensitivity, and selectivity. The novel immobilized GST-tagged Fg is a convenient and efficient enrichment material specific for N-glycans, N-glycopeptides, and N-glycoproteins, suggesting excellent performance and prospects for industrial application.

Effective Identification and Highly Sensitive Quantification of Fructo-oligosaccharide Isomers with Bi2Se3 Nanosheet-Assisted Laser Desorption Ionization Mass Spectrometry.

The growing interest in fructo-oligosaccharides (FOSs) necessitates the effective monitoring of product quality. Identifying and quantifying FOS isomers from the same sources are challenging. Here, we report a new method using Bi2Se3 nanosheets as the matrix for matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), achieving effective differentiation of oligosaccharide isomers through MALDI-MS/MS. Notably, four isomers of pentasaccharides and two isomers of heptasaccharides were successfully identified, with a remarkably low limit of detection of 0.06 pmol. Our approach enabled the specific quantification of 1F-fructofuranosylnystose in commercial FOS products, positioning it as a promising tool for oligosaccharide isomer quantification in nutritional food products. Furthermore, this technique facilitates the rapid and sensitive detection of various saccharides and a wide range of other small molecules with enhanced signal intensities and improved reproducibility. Overall, it facilitates the rapid, selective, and sensitive detection of various saccharides and other small molecules, enhancing analytical chemistry and food science applications.

Magnetic resonance imaging signal changes at the intramuscular injection site in dogs: Comparison of medetomidine and saline.

Intramuscular administration is a commonly used method for delivering sedatives and anesthetics in veterinary medicine. Previous studies have reported inflammation at the intramuscular injection site in laboratory animals and observed signal changes on MRI following intramuscular injections in humans. We hypothesized that following intramuscular injection, the site would exhibit T2 hyperintensity and contrast enhancement on MRI. To investigate this, this prospective study evaluated the pattern of signal changes and grade of T2 signal intensity and contrast enhancement over time after the intramuscular injection of medetomidine at a premedication dosage, comparing it to saline. MRI scans were performed immediately postinjection into the biceps femoris and quadriceps femoris muscles, as well as at 2, 8, 24, and 72h, and 7 days postinjection. A semiquantitative scale was utilized to grade signal intensity and contrast enhancement. Both medetomidine and saline injections showed T2 hyperintensity immediately after injection and contrast enhancement from 2h postinjection, manifesting as flame-shaped. These signal changes decreased up to 24h postinjection (p<.05). The signal changes induced by medetomidine showed higher T2 hyperintense change and stronger contrast enhancement compared with saline at most time points, with the signal changes persisting for a longer duration (p<.05). These findings suggest that intramuscular administration of medetomidine induces a more severe tissue reaction compared with saline, and the results are expected to aid in the differentiation of various muscle diseases that present with similar MRI findings.

An intelligent NIR fluorescent dye with dual response to pH and viscosity for investigating the interactions between LDs and mitochondria

The interaction between lipid droplets and mitochondria plays a pivotal role in biological processes including cellular stress, metabolic homeostasis, cellular autophagy and apoptosis. Deciphering the complex interplay between lipid droplets and mitochondria is essential for gaining insights into the fundamental workings of the cell and can have broad implications for the development of therapeutic strategies for various diseases, including metabolic disorders, neurodegenerative diseases, and cancer. In this study, we develop a pH and viscosity-responsive near-infrared (NIR) fluorescent probe PTOH to investigate the interaction between lipid droplets and mitochondria. This probe demonstrates a significant enhancement in fluorescence intensity at 470 nm when the pH increases, while under acidic conditions, its fluorescence intensity at 730 nm intensifies by a factor of 35 with rising system viscosity. Cell imaging experiments revealed that PTOH can effectively discriminate between normal and cancerous cells, as well as detect intracellular pH and viscosity alterations induced by drugs. Additionally, PTOH is utilized to visualize the interaction between lipid droplets and mitochondria and to differentiate between cellular autophagy and apoptosis phenomena, providing a valuable tool for elucidating the mechanisms underlying lipid droplet-mitochondria interactions and their associated diseases.

Immuno-Rolling Circle Amplification (Immuno-RCA): Biosensing Strategies, Practical Applications, and Future Perspectives.

In the rapidly evolving field of life sciences and biomedicine, detecting low-abundance biomolecules, and ultraweak biosignals presents significant challenges. This has spurred a rapid development of analytical techniques aiming for increased sensitivity and specificity. These advancements, including signal amplification strategies and the integration of biorecognition events, mark a transformative era in bioanalytical precision and accuracy. A prominent method among these innovations is immuno-rolling circle amplification (immuno-RCA) technology, which effectively combines immunoassays with signal amplification via RCA. This process starts when a targeted biomolecule, such as a protein or cell, binds to an immobilized antibody or probe on a substrate. The introduction of a circular DNA template triggers RCA, leading to exponential amplification and significantly enhanced signal intensity, thus the target molecule is detectable and quantifiable even at the single-molecule level. This review provides an overview of the biosensing strategy and extensive practical applications of immuno-RCA in detecting biomarkers. Furthermore, it scrutinizes the limitations inherent to these sensors and sets forth expectations for their future trajectory. This review serves as a valuable reference for advancing immuno-RCA in various domains, such as diagnostics, biomarker discovery, and molecular imaging.

Multi-echo three-dimensional (3D) Dixon sequence combined with disodium gadolinium for risk stratification of advanced fibrosis in metabolic dysfunction-associated steatotic liver disease.

The hepatic steatosis and fibrosis related to metabolic dysfunction-associated steatotic liver disease (MASLD) are important factors in the progression. The Multi echo three-dimensional (3D) Dixon sequence can obtain a single breath hold scan for a fat fraction map and an R2* map. The R2* value is usually used to evaluate iron deposition. Whether the change in R2* value is related to liver fibrosis after injection of gadolinium disulfide (Gd) should be noted. This study evaluates the value of enhanced magnetic relaxation time in the risk stratification of liver fibrosis by analyzing the changes in R2* before and after Gd enhancement, and explores the potential application of Multi echo 3D Dixon sequence in one-stop evaluation of MASLD. This retrospective study included 138 MASLD patients who underwent Gadolinum ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) magnetic resonance imaging (MRI) examination in The First Affiliated Hospital of Chongqing Medical University from June 2020 to December 2021. Finally, 90 subjects were divided into moderate and high-risk fibrosis group and low-risk fibrosis group by two-step assessment of liver fibrosis. Multi-echo 3D chemical shift imaging sequence (Q-Dixon) sequences and gradient-echo T1WI (Vibe-Dixon) sequence were performed during the non-enhanced phase and hepatobiliary phase, respectively, and then the signal-intensity enhancement (SE) and magnetic relaxation-time enhancement (RE) values were calculated. The interobserver correlation coefficient was used to evaluate the consistency between observers. Univariate t-test was used to analyze the differences in RE and SE of liver fibrosis among different risk levels. Delong analysis was performed on receiver operating characteristic (ROC) curve to evaluate the difference in diagnostic efficacy between RE and SE in differentiating the risk level of liver fibrosis. Among the 90 patients, 55 (61.1%) belonged to the low-risk group and 35 (38.9%) belonged to the medium-to-high-risk group. The average RE and SE values were 1.23±0.15 and 1.57±0.23 in the low-risk group and 0.99±0.09 and 1.38±0.21 in both the medium-to-high-risk group (P<0.01). The ROC curve showed that the area under the curve (AUC) value of RE was 0.922, with a corresponding optimal threshold of 0.713, sensitivity of 0.852, and specificity of 0.861. The AUC value of SE was 0.724, with a corresponding optimal threshold of 0.352, sensitivity of 0.519, and specificity of 0.833. The AUC difference between RE and SE for the predictive value of different risk assessments was 0.198, and the 95% confidence interval of the difference was 0.084-0.312. The Delong test showed that the difference was significant (P<0.01). Magnetic RE had high effectiveness for distinguishing between liver-fibrosis risk levels. The combination of the Q-Dixon sequence and Gd-EOB-DTPA has the potential of one-stop evaluation of MASLD.

T1-weighted Motion Mitigation in Abdominal MRI: Technical Principles, Clinical Applications, Current Limitations, and Future Prospects.

T1-weighted (T1W) pulse sequences are an indispensable component of clinical protocols in abdominal MRI but usually require multiple breath holds (BHs) during the examination, which not all patients can sustain. Patient motion can affect the quality of T1W imaging so that key diagnostic information, such as intrinsic signal intensity and contrast enhancement image patterns, cannot be determined. Patient motion also has a negative impact on examination efficiency, as multiple acquisition attempts prolong the duration of the examination and often remain noncontributory. Techniques for mitigation of motion-related artifacts at T1W imaging include multiple arterial acquisitions within one BH; free breathing with respiratory gating or respiratory triggering; and radial imaging acquisition techniques, such as golden-angle radial k-space acquisition (stack-of-stars). While each of these techniques has inherent strengths and limitations, the selection of a specific motion-mitigation technique is based on several factors, including the clinical task under investigation, downstream technical ramifications, patient condition, and user preference. The authors review the technical principles of free-breathing motion mitigation techniques in abdominal MRI with T1W sequences, offer an overview of the established clinical applications, and outline the existing limitations of these techniques. In addition, practical guidance for abdominal MRI protocol strategies commonly encountered in clinical scenarios involving patients with limited BH abilities is rendered. Future prospects of free-breathing T1W imaging in abdominal MRI are also discussed. ©RSNA, 2024 See the invited commentary by Fraum and An in this issue.

Improving Spatial Resolution by Reinterpreting Dosage for Laser-Induced Breakdown Spectroscopy Imaging: Conceptualization and Limitations.

Elemental imaging in laser-induced breakdown spectroscopy is usually performed by placing laser shots adjacent to each other on the sample surface without spatial overlap. Seeing that signal intensity is directly related to the amount of ablated material, this restricts either spatial resolution (for a given excitation efficiency) or sensitivity (when reducing the laser spot size). The experimental applicability of a concept involving the spatial overlapping of shots on the sample surface is investigated and compared to the conventional approach. By systematic choice of spacing between laser shots, spatial resolution can be improved to the single digit micrometer range for a given laser spot size. Signal intensity is found to be linearly dependent on the area ablated per shot, facilitating larger signal-to-background ratios with increased spot sizes. Owing to this, the presented approach is also employed to enhance signal intensity, while preserving spatial resolution. The applicability of the method is explored by analyzing samples with distinct thickness of the surface layer, allowing for the assessment of the concept's suitability for different sample types.

Fluorinated 1,7-DO2A-Based Iron(II) Complexes as Sensitive 19F MRI Molecular Probes for Visualizing Renal Dysfunction in Living Mice.

Kidney diseases have become an important global health concern due to their high incidence, inefficient diagnosis, and poor prognosis. Devising direct methods, especially imaging means, to assess renal function is the key for better understanding the mechanisms of various kidney diseases and subsequent development of effective treatment. Herein, we developed a fluorinated ferrous chelate-based sensitive probe, 1,7-DO2A-Fe(II)-F18 (Probe 1), for 19F magnetic resonance imaging (MRI). This highly fluorinated probe (containing 18 chemically equivalent 19F atoms with a fluorine content at 35 wt %) achieves a 15-time enhancement in signal intensity compared with the fluorine-containing ligand alone due to the appropriately regulated 19F relaxation times by the ferrous ion, which significantly increases imaging sensitivity and reduces acquisition time. Owing to its high aqueous solubility, biostability, and biocompatibility, this probe could be rapidly cleared by kidneys, which provides a means for monitoring renal dysfunction via 19F MRI. With this probe, we accomplish in vivo imaging of the impaired renal dysfunction caused by various kidney diseases including acute kidney injury, unilateral ureteral obstruction, and renal fibrosis at different stages. Our study illustrates the promising potential of Probe 1 for in vivo real-time visualization of kidney dysfunction, which is beneficial for the study, diagnosis, and even stratification of different kidney diseases. Furthermore, the design strategy of our probe is inspiring for the development of more high-performance 19F MRI probes for monitoring various biological processes.

Two Cases of Ischemic Optic Neuropathy after Extracorporeal Membrane Oxygenation (ECMO)

Purpose: We report two cases of non-arteritic ischemic optic neuropathy (NAION) following extracorporeal membrane oxygenation (ECMO) treatment.Case summary: (Case 1) A 36-year-old man underwent ECMO treatment. Upon regaining consciousness, he complained of a darkened peripheral visual field and was subsequently referred to an ophthalmologist. His best-corrected visual acuity was 0.9 in the right eye and 0.8 in the left eye. The intraocular pressure measured 12 mmHg in the right eye and 10 mmHg in the left eye; color vision was normal. A visual field test demonstrated concentric visual field defects in both eyes, and a fundus examination revealed a pale optic disc. Optical coherence tomography (OCT) indicated a decrease in retinal nerve fiber layer (RNFL) thickness. (Case 2) A 48-year-old woman underwent ECMO treatment. After regaining consciousness, she reported decreased vision in her right eye. Her best-corrected visual acuity was limited to hand motion in the right eye and was 1.2 in the left eye. A relative afferent pupillary defect in the right eye was observed. Color vision in the right eye was compromised, and a fundus examination revealed a pale optic disc. A visual field test demonstrated total visual field defect in the right eye, while OCT showed decreases in both the RNFL thickness and the ganglion cell-inner plexiform layer thickness of the right eye. Magnetic resonance imaging (MRI) revealed high signal intensity and abnormal enhancement in the right retrobulbar optic nerve.Conclusions: In cases where vision loss and visual field defects are observed following ECMO treatment, differential diagnoses for ischemic optic neuropathy are warranted.

Highly sensitive photoacoustic gas sensor based on near-concentric cavity.

The precise detection of trace gases in the atmosphere is vital for both environmental preservation and human health. Addressing the inherent challenges in enhancing the sensitivity of photoacoustic spectroscopy, a highly sensitive photoacoustic gas detection method utilizing a near-concentric cavity was proposed. By constructing a near-concentric optical cavity, laser reflections within the photoacoustic cell were substantially amplified, resulting in enhanced sensitivity of photoacoustic signal detection. Additionally, to align with the optical path characteristics of the near-concentric cavity, a miniaturized dumbbell-like photoacoustic cell was designed. Characterized by its high-frequency resonance, this design effectively mitigated background noise while maintaining a high sound pressure level. Experimental results demonstrated a remarkable enhancement in both signal intensity and signal-to-noise ratio by factors of 22.06 and 21.26, respectively, compared to traditional excitation methods. According to the 1σ standard, with a laser power of 21 mW, the setup achieved a detection limit of 10.15 ppb for NO2. The corresponding normalized noise equivalent absorption was calculated to be 2.84 × 10-9 cm-1WHz-1/2, with a gas consumption rate of merely 15.19 mL.

An Explainable Deep-learning Model of Proton Auroras on Mars

Proton auroras are widely observed on the dayside of Mars, identified as a significant intensity enhancement in the hydrogen Lyα (121.6 nm) emission at altitudes of ∼110 and 150 km. Solar wind protons penetrating as energetic neutral atoms into Mars’ thermosphere are thought to be primarily responsible for these auroras. Recent observations of spatially localized “patchy” proton auroras suggest a possible direct deposition of protons into Mars’ atmosphere during unstable solar wind conditions. Improving our understanding of proton auroras is therefore important for characterizing the interaction of the solar wind with Mars’ atmosphere. Here, we develop a first purely data-driven model of proton auroras using Mars Atmosphere and Volatile Evolution (MAVEN) in situ observations and limb scans of Lyα emissions between 2014 and 2022. We train an artificial neural network that reproduces individual Lyα intensities and relative Lyα peak intensity enhancements with Pearson correlations of ∼94% and ∼60% respectively for the test data, along with a faithful reconstruction of the shape of the observed altitude profiles of Lyα emission. By performing a Shapley Additive Explanations (SHAP) analysis, we find that solar zenith angle, solar longitude, CO2 atmosphere variability, solar wind speed, and temperature are the most important features for the modeled Lyα peak intensity enhancements. Additionally, we find that the modeled peak intensity enhancements are high for early local-time hours, particularly near polar latitudes, and the induced magnetic fields are weaker. Through SHAP analysis, we also identify the influence of biases in the training data and interdependences between the measurements used for the modeling, and an improvement of those aspects can significantly improve the performance and applicability of the ANN model.