Structure characterization and intestinal immune promotion effect of polysaccharide purified from Alhagi camelorum Fisch.

This study investigated the structure of acid Alhagi camelorum Fischa polysaccharide (aAP) and its impact on intestinal activity in mice. The results showed that aAP comprised of the fucose, arabinose, rhamnose, galactose, glucose, xylose, mannose, galacturonic acid, glucuronic acid with the molar ratio of 0.81:14.97:10.84:11.14:3.26:0.80:0.80:54.92:2.47 with the molecular weight (Mw) of 22.734 kDa. Additionally, the composition of aAP was assessed via FT-IR, methylation, and NMR analyses, indicating that the backbone of the aAP was consisted of →4)-α-D-GalpA-6-OMe-(1 â†’ 4)-α-GalpA-(1 â†’ and →4)-α-D-GalpA-6-OMe-(1 â†’ 2)-α-L-Rhap-(1→, as well as →4)-ß-D-Galp- and →5)-α-L-Araf- for the branched chain. Furthermore, ICR mice underwent intragastric administration of different concentrations of aAP for 7 consecutive days. The results showed that aAP enhanced the murine spleen and thymus indices, promoted the secretion of serum lgG antibody, intestinal lgA antibody and intestinal cytokines, improved the morphology of intestinal villi and crypts, enhanced quantity of intestinal IELs and IgA+ cells, and activated T lymphocytes and DC cells in MLNs. In summary, these findings suggest that the utilization of aAP could enhance the immune response of the murine intestinal mucosa.

Overlooked in-situ sulfur disproportionation fuels dissimilatory nitrate reduction to ammonium in sulfur-based system: Novel insight of nitrogen recovery.

Sulfur-based denitrification is a promising technology in treatments of nitrate-contaminated wastewaters. However, due to weak bioavailability and electron-donating capability of elemental sulfur, its sulfur-to-nitrate ratio has long been low, limiting the support for dissimilatory nitrate reduction to ammonium (DNRA) process. Using a long-term sulfur-packed reactor, we demonstrate here for the first time that DNRA in sulfur-based system is not negligible, but rather contributes a remarkable 40.5 %-61.1 % of the total nitrate biotransformation for ammonium production. Through combination of kinetic experiments, electron flow analysis, 16S rRNA amplicon, and microbial network succession, we unveil a cryptic in-situ sulfur disproportionation (SDP) process which significantly facilitates DNRA via enhancing mass transfer and multiplying 86.7-210.9 % of bioavailable electrons. Metagenome assembly and single-copy gene phylogenetic analysis elucidate the abundant genomes, including uc_VadinHA17, PHOS-HE36, JALNZU01, Thiobacillus, and Rubrivivax, harboring complete genes for ammonification. Notably, a unique group of self-SDP-coupled DNRA microorganism was identified. This study unravels a previously concealed fate of DNRA, which highlights the tremendous potential for ammonium recovery and greenhouse gas mitigation. Discovery of a new coupling between nitrogen and sulfur cycles underscores great revision needs of sulfur-driven denitrification technology.

Analysis of nearly 3000 archaeal genomes from terrestrial geothermal springs sheds light on interconnected biogeochemical processes.

Terrestrial geothermal springs are physicochemically diverse and host abundant populations of Archaea. However, the diversity, functionality, and geological influences of these Archaea are not well understood. Here we explore the genomic diversity of Archaea in 152 metagenomes from 48 geothermal springs in Tengchong, China, collected from 2016 to 2021. Our dataset is comprised of 2949 archaeal metagenome-assembled genomes spanning 12 phyla and 392 newly identified species, which increases the known species diversity of Archaea by ~48.6%. The structures and potential functions of the archaeal communities are strongly influenced by temperature and pH, with high-temperature acidic and alkaline springs favoring archaeal abundance over Bacteria. Genome-resolved metagenomics and metatranscriptomics provide insights into the potential ecological niches of these Archaea and their potential roles in carbon, sulfur, nitrogen, and hydrogen metabolism. Furthermore, our findings illustrate the interplay of competition and cooperation among Archaea in biogeochemical cycles, possibly arising from overlapping functional niches and metabolic handoffs. Taken together, our study expands the genomic diversity of Archaea inhabiting geothermal springs and provides a foundation for more incisive study of biogeochemical processes mediated by Archaea in geothermal ecosystems.

Improving the microbiological safety and quality of aquatic products using nonthermal processing.

Spoilage and deterioration of aquatic products during storage are inevitable, posing significant challenges to their suitability for consumption and the sustainability of the aquatic products supply chain. Research on the nonthermal processing of fruit juices, probiotics, dairy products, and meat has demonstrated positive outcomes in preserving quality. This review examines specific spoilage bacteria species and mechanisms for various aquatic products and discusses the principles, characteristics, and applications of six nonthermal processing methods for bacterial inhibition to maintain microbiological safety and physicochemical quality. The primary spoilage bacteria groups differ among fish, crustaceans, and shellfish based on storage conditions and durations. Four metabolic pathways utilized by spoilage microorganisms-peptides and amino acids, nitrogen compounds, nucleotides, and carbohydrates-are crucial in explaining spoilage. Nonthermal processing techniques, such as ultrahigh pressure, irradiation, magnetic/electric fields, plasma, and ultrasound, can inactivate microorganisms, thereby enhancing microbiological safety, physicochemical quality, and shelf life. Future research may integrate nonthermal processing with other technologies (e.g., modified atmosphere packaging and omics) to elucidate mechanisms of spoilage and improve the storage quality of aquatic products.

Design, synthesis, and evaluation of novel quindoline derivatives with fork-shaped side chains as RNA G-quadruplex stabilizers for repressing oncogene NRAS translation.

NRAS mutation is the second most common oncogenic factor in cutaneous melanoma. Inhibiting NRAS translation by stabilizing the G-quadruplex (G4) structure with small molecules seems to be a potential strategy for cancer therapy due to the NRAS protein's lack of a druggable pocket. To enhance the effects of previously reported G4 stabilizers quindoline derivatives, we designed and synthesized a novel series of quindoline derivatives with fork-shaped side chains by introducing (alkylamino)alkoxy side chains. Panels of experimental results showed that introducing a fork-shaped (alkylamino)alkoxy side chain could enhance the stabilizing abilities of the ligands against NRAS RNA G-quadruplexes and their anti-melanoma activities. One of them, 10b, exhibited good antitumor activity in the NRAS-mutant melanoma xenograft mouse model, showing the therapeutic potential of this kind of compounds.

17ß-Estradiol protects female rats from bilateral oophorectomy-induced nonalcoholic fatty liver disease induced by improving linoleic acid metabolism alteration and gut microbiota disturbance.

After surgical or natural menopause, women face a high risk of nonalcoholic fatty liver disease (NAFLD), which can be diminished by hormone replacement therapy (HRT). The gut microbiota is subject to modulation by various physiological changes and the progression of diseases. This microbial ecosystem coexists symbiotically with the host, playing pivotal roles in immune maturation, microbial defense mechanisms, and metabolic functions essential for nutritional and hormone homeostasis. E2 supplementation effectively prevented the development of NAFLD after bilateral oophorectomy (OVX) in female rats. The changes in the gut microbiota such as abnormal biosynthetic metabolism of fatty acids caused by OVX were partially restored by E2 supplementation. The combination of liver transcriptomics and metabolomics analysis revealed that linoleic acid (LA) metabolism, a pivotal pathway in fatty acids metabolism was mainly manipulated during the induction and treatment of NAFLD. Further correlation analysis indicated that the gut microbes were associated with abnormal serum indicators and different LA metabolites. These metabolites are also closely related to serum indicators of NAFLD. An in vitro study verified that LA is an inducer of hepatic steatosis. The changes in transcription in the LA metabolism pathway could be normalized by E2 treatment. The metabolic perturbations of LA may directly and secondhand impact the development of NAFLD in postmenopausal individuals. This research focused on the sex-specific pathophysiology and treatment of NAFLD, providing more evidence for HRT and calling for the multitiered management of NAFLD.

CloudMix: Dual Mixup Consistency for Unpaired Point Cloud Completion.

Due to the unsatisfactory performance of supervised methods on unpaired real-world scans, point cloud completion via cross-domain adaptation has recently drawn growing attention. Nevertheless, previous approaches only focus on alleviating the distribution shift through domain alignment, resulting in massive information loss of real-world domain data. To tackle this issue, we propose a dual mixup-induced consistency regularization to integrate both source and target domain to improve robustness and generalization capability. Specifically, we mix up virtual and real-world shapes in the input and latent feature space respectively, and then regularize the completion network by forcing two kinds of mixed completion predictions to be consistent. To further adapt to each instance within the real-world domain, we design a novel density-aware refiner to utilize local context information to preserve the fine-grained details and remove noise or outliers for coarse completion. Extensive experiments on real-world scans and our synthetic unpaired datasets demonstrate the superiority of our method over existing state-of-the-art approaches.

Anisotropic sensing based on single ReS2flake for VOCs discrimination.

Selective and sensitive detection of volatile organic compounds (VOCs) holds paramount importance in real-world applications. This study proposes an innovative approach utilizing a single ReS2field-effect transistor (FET) characterized by distinct in-plane anisotropy, specifically tailored for VOC recognition. The unique responses of ReS2, endowed with robust in-plane anisotropic properties, demonstrate significant difference along thea-axis andb-axis directions when exposed to four kinds of VOCs: acetone, methanol, ethanol, and IPA. Remarkably, the responses of ReS2were significantly magnified under ultraviolet (UV) illumination, particularly in the case of acetone, where the response amplified by 10-15 times and the detection limit decreasing from 70 to 4 ppm compared to the dark conditions. Exploiting the discernible variances in responses along thea-axis andb-axis under both UV and dark conditions, the data points of acetone, ethanol, methanol and IPA gases were clearly separated in the principal component space without any overlap through principal component analysis, indicating that the single ReS2FET has a high ability to distinguish various gas species. The exploration of anisotropic sensing materials and light excitation strategies can be applied to a broad range of sensing platforms based on two-dimensional materials for practical applications.

Cyclooctatetraene-Embedded Carbon Nanorings.

With the prosperity of the development of carbon nanorings, certain topologically or functionally unique units-embedded carbon nanorings have sprung up in the past decade. Herein, we report the facile and efficient synthesis of three cyclooctatetraene-embedded carbon nanorings (COTCNRs) that contain three (COTCNR1 and COTCNR2) and four (COTCNR3) COT units in a one-pot Yamamoto coupling. These nanorings feature hoop-shaped segments of Gyroid (G-), Diamond (D-), and Primitive (P-) type carbon schwarzites. The conformations of the trimeric nanorings COTCNR1 and COTCNR2 are shape-persistent, whereas the tetrameric COTCNR3 possesses a flexible carbon skeleton which undergoes conformational changes upon forming host-guest complexes with fullerenes (C60 and C70), whose co-crystals may potentially serve as fullerene-based semiconducting supramolecular wires with electrical conductivities on the order of 10-7 S cm-1 (for C60⊂COTCNR3) and 10-8 S cm-1 (for C70⊂COTCNR3) under ambient conditions. This research not only describes highly efficient one-step syntheses of three cyclooctatetraene-embedded carbon nanorings which feature hoop-shaped segments of distinctive topological carbon schwarzites, but also demonstrates the potential application in electronics of the one-dimensional fullerene arrays secured by COTCNR3.

Structural and functional basis of bacteriophage K64-ORF41 depolymerase for capsular polysaccharide degradation of Klebsiella pneumoniae K64.

Capsule polysaccharide is an important virulence factor of Klebsiella pneumoniae (K. pneumoniae), which protects bacteria against the host immune response. A promising therapeutic approach is using phage-derived depolymerases to degrade the capsular polysaccharide and expose and sensitize the bacteria to the host immune system. Here we determined the cryo-electron microscopy (cryo-EM) structures of a bacteriophage tail-spike protein against K. pneumoniae K64, ORF41 (K64-ORF41) and ORF41 in EDTA condition (K64-ORF41EDTA), at 2.37 Å and 2.50 Å resolution, respectively, for the first time. K64-ORF41 exists as a trimer and each protomer contains a ß-helix domain including a right-handed parallel ß-sheet helix fold capped at both ends, an insertion domain, and one ß-sheet jellyroll domain. Moreover, our structural comparison with other depolymerases of K. pneumoniae suggests that the catalytic residues (Tyr528, His574 and Arg628) are highly conserved although the substrate of capsule polysaccharide is variable. Besides that, we figured out the important residues involved in the substrate binding pocket including Arg405, Tyr526, Trp550 and Phe669. This study establishes the structural and functional basis for the promising phage-derived broad-spectrum activity depolymerase therapeutics and effective CPS-degrading agents for the treatment of carbapenem-resistant K. pneumoniae K64 infections.

Image Understands Point Cloud: Weakly Supervised 3D Semantic Segmentation via Association Learning.

Weakly supervised point cloud semantic segmentation methods that require 1% or fewer labels with the aim of realizing almost the same performance as fully supervised approaches have recently attracted extensive research attention. A typical solution in this framework is to use self-training or pseudo-labeling to mine the supervision from the point cloud itself while ignoring the critical information from images. In fact, cameras widely exist in LiDAR scenarios, and this complementary information seems to be highly important for 3D applications. In this paper, we propose a novel cross-modality weakly supervised method for 3D segmentation that incorporates complementary information from unlabeled images. We design a dual-branch network equipped with an active labeling strategy to maximize the power of tiny parts of labels and to directly realize 2D-to-3D knowledge transfer. Afterward, we establish a cross-modal self-training framework, which iterates between parameter updating and pseudolabel estimation. In the training phase, we propose cross-modal association learning to mine complementary supervision from images by reinforcing the cycle consistency between 3D points and 2D superpixels. In the pseudolabel estimation phase, a pseudolabel self-rectification mechanism is derived to filter noisy labels, thus providing more accurate labels for the networks to be fully trained. The extensive experimental results demonstrate that our method even outperforms the state-of-the-art fully supervised competitors with less than 1% actively selected annotations.

CSFwinformer: Cross-Space-Frequency Window Transformer for Mirror Detection.

Mirror detection is a challenging task since mirrors do not possess a consistent visual appearance. Even the Segment Anything Model (SAM), which boasts superior zero-shot performance, cannot accurately detect the position of mirrors. Existing methods determine the position of the mirror under hypothetical conditions, such as the correspondence between objects inside and outside the mirror, and the semantic association between the mirror and surrounding objects. However, these assumptions do not apply to all scenarios. For instance, there may be no corresponding real objects to the reflected objects in the scene, or it may be challenging to extract meaningful semantic associations in complex scenes. On the other hand, humans can easily recognize mirrors through the specular texture caused by materials. To mine mirror features in more general scenes, we propose a Cross-Space-Frequency Window Transformer (CSFwinformer) to extract spatial and frequency features for texture analysis. Specifically, we design a Spatial-Frequency Window Alignment module (SFWA) to calculate spatial-frequency feature affinities and learn the difference between mirror and non-mirror textures. We then propose a Dilated Window Attention (DWA) to extract global features to complement the limitation of window alignment. Besides, we propose a Cross-Modality Context Contrast module (CMCC) to fuse cross-modality features and global features, which enables information flow between different windows to take full advantage of cross-modality information. Extensive experiments show that our method performs favorably against state-of-the-art methods on three mirror detection benchmarks and significantly improved SAM performance on mirror detection. The code is available at https://github.com/wangsen99/CSFwinformer.

Clinical rules of Acupoint selection for cancer pain opioid-induced constipation based on journal literature data mining: A systematic review.

Objective: To analyse and summarise the regularity of acupoint selection in the treatment of opioid-induced constipation (OIC) in patients with cancer pain using a data mining technique and provide a reference for clinical practice and more valuable treatment options. Methods: The acupoint prescription database for the treatment of OIC-related cancer pain was established by searching the relevant literature on randomised controlled trials involving acupoint therapy for OIC-related cancer pain in seven major databases, including the China National Knowledge Infrastructure, Wanfang and VIP Chinese scientific journal databases, from database establishment to December 31, 2022. The main therapeutic measures of acupoint prescription, frequency of acupoint use and its subordinate meridians and subordinate sites were then analysed. Through systematic clustering and association rule analysis, the core acupoint prescriptions and most commonly used acupoint compatibility of acupoint therapy for OIC-related cancer pain were obtained. Results: A total of 649 articles were retrieved, with 72 articles included after screening. The treatment measures were found to be mainly acupoint applications involving 28 acupoints, with a total frequency of 234. The three most frequently used acupoints were Shenque, Tianshu and Zusanli. The number of points used in the Foot-Yangming stomach meridian was the highest. Commonly used acupoints were mainly distributed in the abdomen. The compatibility of two commonly used acupoints was obtained through systematic clustering. Through association rule analysis, it was found that in the compatibility of acupoints, the strongest correlation was between Tianshu and Zusanli, and their frequency of application was the highest. Conclusion: Tianshu and Zusanli are the core acupoints for acupoint therapy in the treatment of OIC-related cancer pain, and the Shangjuxu-Zhigou-Zusanli, Qihai-Guanyuan and Zhongwan-Tianshu acupoints exhibit the highest compatibility. This study provides a reference for the clinical acupoint selection programme of acupuncture and moxibustion in the treatment of OIC-related cancer pain.

Targeting cAMP in D1-MSNs in the nucleus accumbens, a new rapid antidepressant strategy.

Studies have suggested that the nucleus accumbens (NAc) is implicated in the pathophysiology of major depression; however, the regulatory strategy that targets the NAc to achieve an exclusive and outstanding anti-depression benefit has not been elucidated. Here, we identified a specific reduction of cyclic adenosine monophosphate (cAMP) in the subset of dopamine D1 receptor medium spiny neurons (D1-MSNs) in the NAc that promoted stress susceptibility, while the stimulation of cAMP production in NAc D1-MSNs efficiently rescued depression-like behaviors. Ketamine treatment enhanced cAMP both in D1-MSNs and dopamine D2 receptor medium spiny neurons (D2-MSNs) of depressed mice, however, the rapid antidepressant effect of ketamine solely depended on elevating cAMP in NAc D1-MSNs. We discovered that a higher dose of crocin markedly increased cAMP in the NAc and consistently relieved depression 24 h after oral administration, but not a lower dose. The fast onset property of crocin was verified through multicenter studies. Moreover, crocin specifically targeted at D1-MSN cAMP signaling in the NAc to relieve depression and had no effect on D2-MSN. These findings characterize a new strategy to achieve an exclusive and outstanding anti-depression benefit by elevating cAMP in D1-MSNs in the NAc, and provide a potential rapid antidepressant drug candidate, crocin.

Induction Chemotherapy Followed by Radiotherapy vs Chemoradiotherapy in Nasopharyngeal Carcinoma: A Randomized Clinical Trial.

Importance: Induction chemotherapy plus concurrent chemoradiotherapy is recommended for locoregionally advanced nasopharyngeal carcinoma but is associated with higher rates of acute toxic effects and low compliance. Evidence on de-escalating treatment intensity after induction chemotherapy is limited. Objective: To assess if radiotherapy was noninferior to chemoradiotherapy after induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma. Design, Setting, and Participants: From April 2015 to March 2018, a multicenter, open-label, randomized, noninferiority, phase 3 trial was conducted at 5 Chinese hospitals. A total of 383 patients aged 18 to 70 years with an untreated histologically confirmed nonkeratinizing tumor, Karnofsky performance status score not worse than 70, proper organ function, and stage III to IVB nasopharyngeal cancer were enrolled. Data were analyzed from April 2023 to June 2023. Interventions: Patients were assigned randomly. Both groups received 3 cycles of induction chemotherapy consisting of intravenous administration (on day 1) of cisplatin at 60 mg/m2 and docetaxel at 60 mg/m2 and continuous intravenous infusion (from day 1 to day 5) of daily fluorouracil (600 mg/m2), repeated every 21 days. Subsequently, the patients received radiotherapy alone (induction chemotherapy in combination with radiotherapy [IC-RT] group) or concomitant cisplatin (30 mg/m2/week) with radiotherapy for 6 to 7 weeks (induction chemotherapy combined with chemoradiotherapy [IC-CCRT] group). Main Outcomes and Measures: The primary end point was 3-year progression-free survival (time from the initiation of therapy until the first indication of disease progression or death), with a noninferiority margin of 10%. The secondary end points included overall survival, locoregional failure-free survival, distant metastasis-free survival, response rate, and toxic effects. Results: A total of 383 patients (median [range] age, 48 [19-70] years; 100 women [26%]). Median follow-up time was 76 months (IQR, 70-89 months). The 3-year progression-free survival was 76.2% and 76.8% in the IC-RT (n = 193) and IC-CCRT groups (n = 190), respectively, in the intention-to-treat population, showing a difference of 0.6% (95% CI, -7.9% to 9.1%; P = .01 for noninferiority). Identical outcomes were reported in the per-protocol population. The incidence of grade 3 to 4 short-term toxic effects in the IC-RT group was less than the IC-CCRT group. No differences were observed in late toxic effects. Conclusions and Relevance: The results of this randomized clinical trial suggest that after induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma, radiotherapy alone was noninferior to chemoradiotherapy in terms of 3-year progression-free survival. Trial Registration: ClinicalTrials.gov Identifier: NCT02434614.

Assessing the stress-relief impact of an art-based intervention inspired by the broaden-and-build theory in college students.

Background and objectives: This study's primary objective is to investigate the impact of art-making on the mental well-being of college students, who often experience heightened stress during their initial university years. Methods: Employing a comprehensive methodology, combining interviews and the Perceived Stress Scale (PSS), the research aimed to assess whether a four-week art-making intervention can effectively alleviate stress levels among college students. In the experimental group, participants engaged in a variety of art-making activities, including freehand drawing, clay modeling, and crafting. Results: The results revealed that, in the pre-test, there were no significant differences between the experimental and control groups for each assessed indicator. However, in the post-test, significant differences emerged across all indicators. Further analysis demonstrated a significant reduction in stress perception among the experimental group participants between the pre-test and post-test phases. Conclusion: In conclusion, this study provides compelling evidence that art-making has the potential to foster positive personal development and significantly reduce stress levels among college students.

Temperature, pH, and oxygen availability contributed to the functional differentiation of ancient Nitrososphaeria.

Ammonia-oxidizing Nitrososphaeria are among the most abundant archaea on Earth and have profound impacts on the biogeochemical cycles of carbon and nitrogen. In contrast to these well-studied ammonia-oxidizing archaea (AOA), deep-branching non-AOA within this class remain poorly characterized because of a low number of genome representatives. Here, we reconstructed 128 Nitrososphaeria metagenome-assembled genomes from acid mine drainage and hot spring sediment metagenomes. Comparative genomics revealed that extant non-AOA are functionally diverse, with capacity for carbon fixation, carbon monoxide oxidation, methanogenesis, and respiratory pathways including oxygen, nitrate, sulfur, or sulfate, as potential terminal electron acceptors. Despite their diverse anaerobic pathways, evolutionary history inference suggested that the common ancestor of Nitrososphaeria was likely an aerobic thermophile. We further surmise that the functional differentiation of Nitrososphaeria was primarily shaped by oxygen, pH, and temperature, with the acquisition of pathways for carbon, nitrogen, and sulfur metabolism. Our study provides a more holistic and less biased understanding of the diversity, ecology, and deep evolution of the globally abundant Nitrososphaeria.

3D-Printed Origami Actuators for a Multianimal-Inspired Soft Robot with Amphibious Locomotion and Tongue Hunting.

The field of soft robotics is rapidly evolving, and there is a growing interest in developing soft robots with bioinspired features for use in various applications. This research presented the design and development of 3D-printed origami actuators for a soft robot with amphibious locomotion and tongue hunting capabilities. Two different types of programmable origami actuators were designed and manufactured, namely Z-shaped and twist tower actuators. In addition, two actuator variations were developed based on the Z-shaped actuator, including the pelvic fin and the coiling/uncoiling types. The Z-shaped actuators were used for the rear legs to facilitate the locomotion of the water-like frogs. Meanwhile, the twisted tower actuators were used for the rotation joints in the forelegs and for locomotion on land. The pelvic fin actuator was developed to imitate the land locomotion of the mudskipper, and the coiling/uncoiling actuator was designed for tongue hunting motion. The origami actuators and soft robot prototype were tested through a series of experiments, which showed that the robot was capable of efficiently moving in water and on land and performing tongue hunting motions. Our results demonstrate the effectiveness of these actuators in producing the desired motions and provide insights into the potential of applying 3D-printed origami actuators in the development of soft robots with bioinspired features.

Quantitative ultrasound image assessment of the optic nerve subarachnoid space during 90-day head-down tilt bed rest.

The elevation in the optic nerve sheath (ONS) pressure (ONSP) due to microgravity-induced headward fluid shift is the primary hypothesized contributor to SANS. This longitudinal study aims to quantify the axial plane of the optic nerve subarachnoid space area (ONSSA), which is filled with cerebrospinal fluid (CSF) and expands with elevated ONSP during and after head-down tilt (HDT) bed rest (BR). 36 healthy male volunteers (72 eyes) underwent a 90-day strict 6° HDT BR. Without obtaining the pre-HDT data, measurements were performed on days 30, 60, and 90 during HDT and at 6 recovery time points extended to 180-days (R + 180) in a supine position. Portable B-scan ultrasound was performed using the 12 MHz linear array probe binocularly. The measurements of the ONS and the calculation of the ONSSA were performed with ImageJ 1.51 analysis software by two experienced observers in a masked manner. Compared to R + 180, the ONSSA on HDT30, HDT60, and HDT90 exhibited a consistently significant distention of 0.44 mm2 (95% CI: 0.13 to 0.76 mm2, P = 0.001), 0.45 mm2 (95% CI: 0.15 to 0.75 mm2, P = 0.001), and 0.46 mm2 (95% CI: 0.15 to 0.76 mm2, P < 0.001), respectively, and recovered immediately after HDT on R + 2. Such small changes in the ONSSA were below the lateral resolution limit of ultrasound (0.4 mm) and may not be clinically relevant, possibly due to ONS hysteresis causing persistent ONS distension. Future research can explore advanced quantitative portable ultrasound-based techniques and establish comparisons containing the pre-HDT measurements to deepen our understanding of SANS.