Nitidine chloride regulates cell function of bladder cancer in vitro through downregulating Lymphocyte antigen 75.

Nitidine chloride (NC) is effective on cancer in many tumors, but its effect on bladder cancer (BC) is unknown. We conducted cell function experiments to verify the antineoplastic effect of NC on BC cell lines (5637, T24, and UM-UC-3) in vitro. Then, mRNAs of NC-treated and NC-untreated BC cells were extracted for mRNA sequencing. Differentially expressed genes (DEGs), expression analysis, and drug molecular docking were conducted to discover the target gene of NC. Finally, functional enrichment was analyzed to explore the underlying mechanisms. NC dramatically inhibited proliferation, migration, and invasion, and it induced apoptosis and arrested the S and G2/M phases of BC cell lines. Lymphocyte antigen 75 (LY75) appeared to be the target of NC. LY75 was highly expressed and had the ability to distinguish BC tissue from non-cancerous tissue. Then, drug molecular docking confirmed the targeting relationship between NC and LY75. Gene enrichment analysis showed that the downregulated genes, after being treated with NC, were mainly enriched in pathways relevant to cell pathophysiological processes. NC inhibits BC cell proliferation, migration, and invasion, induces apoptosis, and arrests cell cycles by downregulating the expression of LY75. This study provides molecular and theoretical bases for NC treatment of BC.

A case report of acute suppurative thyroiditis caused by Clostridium perfringens.

A 42-year-old woman inadvertently discovered a neck mass, which caused pain. Initially, she was treated with antibiotics at a local clinic; however, this treatment did not alleviate the symptoms. She visited the authors' outpatient clinic for further treatment and underwent thyroid ultrasonography, which revealed a mixed echo nodule. On day 4 after admission, surgery was performed to remove the diseased thyroid tissue and levofloxacin (0.4 g/day) was infused. Bacterial culture confirmed infection with Clostridium perfringens. Subsequently, the treatment was switched to ceftriaxone sodium (2 g/day) according to the results of the drug sensitivity test. Following treatment, the patient recovered fully and was discharged. She was then followed up with after discharge. Ultrasonography, laboratory testing and clinical manifestations did not indicate obvious abnormalities.

Washing-free electrogenerated chemiluminescence magnetic microbiosensors based on target assistant proximity hybridization for multiple protein biomarkers.

This work reports washing-free electrogenerated chemiluminescence (ECL) magnetic microbiosensors based on target assistant proximity hybridization (TAPH) for multiple protein biomarkers for the first time. As a principle-of-proof, alpha-fetoprotein (AFP) was chosen as a model analyte, and biotin-DNA1 bound streptavidin-coated magnetic microbeads (MMB@SA⋅biotin-DNA1) were designed as the universal capture MMB, while the corresponding two antibodies tagged with DNA2 or DNA3 were utilized as hybrid recognition probes, and ruthenium complex-tagged DNA4-10A was designed as a universal ECL signal probe. When the capture MMB was added into the mixture solution (containing the analyte, hybrid recognition probes, signal probe and tri-n-propylamine), biocomplexes were formed on the MMB. After the resulting MMB was efficiently brought to the surface of a magnetic glassy carbon electrode (MGCE), ECL measurement was performed without a washing step, resulting in an increase in the ECL intensity. A model for ECL measuring the second-order rate constants of hybridization reactions on MMB was derived. It was found that the rate constants for hybridization reactions on MMB in rotating mode are 1.6-fold higher than those in shaking mode, and a suitable DNA length of the signal probe can improve the signal-to-noise ratio. The washing-free ECL method was developed for the determination of AFP with a much lower detection limit (LOD) of 0.04 ng mL-1. The developed flexible strategy has been extended to determine D-dimer with an LOD of 0.1 ng mL-1 and myoglobinglobin with an LOD of 1.1 ng mL-1. This work demonstrated that the proposed strategy of ECL TAPH on MMB at MGCE is a washing-free and flexible promising strategy, and can be extended to qualify other multiple protein biomarkers in real clinical assays.

Bispecific antibodies targeting immunomodulatory checkpoints for cancer therapy.

Advances in antibody engineering have led to the generation of more innovative antibody drugs, such as bispecific antibodies (bsAbs). Following the success associated with blinatumomab, bsAbs have attracted enormous interest in the field of cancer immunotherapy. By specifically targeting two different antigens, bsAbs reduce the distance between tumor and immune cells, thereby enhancing tumor killing directly. There are several mechanisms of action upon which bsAbs have been exploited. Accumulating experience on checkpoint-based therapy has promoted the clinical transformation of bsAbs targeting immunomodulatory checkpoints. Cadonilimab (PD-1 × CTLA-4) is the first approved bsAb targeting dual inhibitory checkpoints, which confirms the feasibility of bsAbs in immunotherapy. In this review we analyzed the mechanisms by which bsAbs targeting immunomodulatory checkpoints and their emerging applications in cancer immunotherapy.

Down-regulation and clinical significance of Sorbin and SH3 domain-containing protein 1 in bladder cancer tissues.

Bladder cancer (BC) is a common cancer worldwide with a high prevalence. This study was conducted to elucidate the expression and clinical significance of Sorbin and SH3 domain-containing protein 1 (SORBS1) in BC as well as to explore its molecular mechanism in BC tumourigenesis. RNA-sequencing data, microarray, and Immunohistochemistry (IHC) were applied to elucidated the SORBS1 expression at multiple levels. After that, the relationship between tumour-immune infiltration and SORBS1 was also explored. Finally, SORBS1-related genes in BC were identified to perform functional enrichment analyses. The expression integration revealed that the comprehensive expression of SORBS1 at the mRNA level was -1.02 and that at the protein level was -3.73, based on 12 platforms, including 1221 BC and 187 non-BC samples. SORBS1 was negatively correlated with tumour purity (correlation = -0.342, p < 0.001) and positively correlated with macrophage (correlation = 0.358, p < 0.001). The results of enrichment analyses revealed that the most significant biological pathways of SORBS1-related genes were epithelial-mesenchymal transition. SORBS1 was significantly down-regulated in BC and may play a role as tumour suppressor. This study provides new directions and biomarkers for future BC diagnosis.

SSH1 promotes progression of intrahepatic cholangiocarcinoma via p38 MAPK-CXCL8 axis.

Protein tyrosine phosphatases (PTPs) are involved in malignant transformation and metastasis. According to one of our previous studies, Slingshot homolog 1 (SSH1), a member of PTPs, is significantly associated with the survival of intrahepatic cholangiocarcinoma (iCCA) patients. However, the underlying mechanisms of SSH1 in iCCA remain largely elusive. Here, the expression and clinical significance of SSH1 were assessed using the iCCA patient samples. The results showed that SSH1 was dramatically up-regulated in iCCA tissues and elevated SSH1 expression was associated with worse overall survival of iCCA patients. Overexpression of SSH1 accelerated the proliferation, migration and invasion of iCCA cells, and also inhibited cell apoptosis. Furthermore, the downstream signaling pathway of SSH1 in iCCA was explored and it was revealed that the increased expression of SSH1 could activate the p38 MAPK pathway and enhance the expression of CXCL8. Notably, the high correlation of SSH1 with CXCL8 jointly indicated the poor prognosis in iCCA patients. Thus, our study suggests SSH1 as a potentially promising target for iCCA, which promoted iCCA progression through a potential p38 MAPK-CXCL8 axis.

An adaptive absorption spectroscopy with adjustable moving window width for suppressing nonlinear effects in absorbance measurements.

Absorption spectroscopy based on Lambert-Beer law has been widely used in material structure analysis, research in chemical reaction kinetics, and exploration of various physicochemical reaction mechanisms. However, serious nonlinearity between absorbance and measured concentration can occur in actual measurements. The idea of moving window is first introduced into the field of spectral nonlinearity in the paper. Combining with the characteristic absorption spectra of the substances to be measured, we propose an adaptive absorption spectroscopy (A-AS) with adjustable moving window parameters to effectively suppress the nonlinear effects in absorbance measurements. The validity of this method is verified by taking the differential optical absorption spectroscopy to detect SO2 as an example. The 210-230 nm characteristic absorption band is traversed and divided by the moving window with adjustable parameters, and the estimated coefficient (k-value) of each band is calculated. On this basis, all k-values are initially and secondly screened to obtain the optimal kbest, and then the optimal concentration value is obtained by inversion. Compared with the broad-band method and narrow-band method, it shows excellent performance that the maximum error and standard deviation of A-AS is only 1.3% and 3.8 in the entire concentration range, suggesting good linearity and stability in both high and low concentration environments. Therefore, it is inferred that A-AS is universally adaptable and enables dynamic linear measurements over wide concentration range.

Inhibition of autophagy in macrophage promotes IL-1ß-mediated hepatocellular carcinoma progression via inflammasome accumulation and self-recruitment.

Hepatocellular carcinoma (HCC) has a complex and changeable tumor microenvironment. Despite emerging evidence focusing on autophagy process within immune cells, the function and regulatory mechanism of macrophage autophagy in tumor progression remains unclear. Our results of multiplex-immunohistochemistry and RNA-sequencing identified the reduced levels of autophagy in tumor macrophages in the HCC microenvironment, associated with a poor prognosis and increased microvascular metastasis in HCC patients. Specifically, HCC suppressed the macrophage autophagy initiation through the up-regulation of mTOR and ULK1 phosphorylation at Ser757. Knockdown of autophagy-related proteins to further inhibit autophagy significantly boosted the metastatic potential of HCC. Mechanistically, the accumulation of NLRP3 inflammasome mediated by autophagy inhibition promoted the cleavage, maturation, and release of IL-1ß, which facilitated the HCC progression, eventually accelerating HCC metastasis via the epithelial-mesenchymal transition. Autophagy inhibition provoked macrophage self-recruitment through the CCL20-CCR6 signaling was also a crucial account of HCC progression. Recruited macrophages mediated the cascade amplification of IL-1ß and CCL20 to form a novel pro-metastatic positive feedback loop through promoting HCC metastasis and increased macrophage recruitment, respectively. Notably, targeting IL-1ß/IL-1 receptor signaling impaired lung metastasis induced by macrophage autophagy inhibition in a mice HCC lung metastasis model. In summary, this study highlighted that inhibition of tumor macrophage autophagy facilitated HCC progression by increasing IL-1ß secretion via NLRP3 inflammasome accumulation and by macrophage self-recruitment through the CCL20 signaling pathway. Interruption of this metastasis-promoting loop by IL-1ß blockade may provide a promising therapeutic strategy for HCC patients.

Engineering PEDOT:PSS/PEG Fibers with a Textured Surface toward Comprehensive Personal Thermal Management.

The wild environment is unpredictable where soaring or plummeting temperatures in extreme weather events can pose serious threats to human lives. Incorporating passive evaporative cooling and controllable electric heating into clothing could effectively protect human beings from such harsh environments. In this work, poly(3,4-ethylene dioxy thiophene):poly(styrene sulfonate)/poly(ethylene glycol) (PPP) fibers with the core-shell structure and attractively textured surface have been successfully prepared via a single-nozzle wet-spinning technique. Results show that the fibers possess fascinating specific surface area (184.8 m2·g-1), electrical conductivity (50 S·cm-1), and stretchability (>100%) because of the novel preparation method and hierarchical morphological design. Through simple textile manufacturing routes, PPP fibers can be woven into fabrics easily, which exhibit desirable breathability, washability, and mechanical strength for smart textiles while maintaining favorable hygroscopicity. Benefiting from the textured structure with large specific surface area, PPP fabric exhibits attractile evaporative cooling rate. Practical application tests have demonstrated that under direct sunlight, the surface temperature of the PPP fabric is ∼5.2 and ∼10.8 °C lower than commercial cotton and polyester fabrics, respectively. Meanwhile, as conductive fibers, the resultant PPP fabric can heat under low-power electricity, therefore achieving the effect of "warmth in winter and coolness in summer". The facile fabrication process and elevated performance of PPP fibers present significant advantages for applications in intelligent garments and textiles, as well as comprehensive personal thermal management, which opens a new avenue for future design in these fields.

Toripalimab combined with lenvatinib and GEMOX is a promising regimen as first-line treatment for advanced intrahepatic cholangiocarcinoma: a single-center, single-arm, phase 2 study.

Advanced intrahepatic cholangiocarcinoma (ICC) has a dismal prognosis. Here, we report the efficacy and safety of combining toripalimab, lenvatinib, and gemcitabine plus oxaliplatin (GEMOX) as first-line therapy for advanced ICC. Thirty patients with pathologically confirmed advanced ICC received intravenous gemcitabine (1 g/m2) on Days 1 and 8 and oxaliplatin (85 mg/m2) Q3W for six cycles along with intravenous toripalimab (240 mg) Q3W and oral lenvatinib (8 mg) once daily for one year. The expression of programmed death-ligand 1 (PD-L1) and genetic status was investigated in paraffin-embedded tissues using immunohistochemistry and whole-exome sequencing (WES) analysis. The primary endpoint was the objective response rate (ORR). Secondary outcomes included safety, overall survival (OS), progression-free survival (PFS), disease control rate (DCR) and duration of response (DoR). As of July 1, 2022, the median follow-up time was 23.5 months, and the ORR was 80%. Twenty-three patients achieved partial response, and one achieved complete response. Patients (21/30) with DNA damage response (DDR)-related gene mutations showed a higher ORR, while patients (14/30) with tumor area positivity ≥1 (PD-L1 staining) showed a trend of high ORR, but without significant difference. The median OS, PFS, and DoR were 22.5, 10.2, and 11.0 months, respectively. The DCR was 93.3%. Further, 56.7% of patients experienced manageable grade ≥3 adverse events (AEs), commonly neutropenia (40.0%) and leukocytopenia (23.3%). In conclusion, toripalimab plus lenvatinib and GEMOX are promising first-line regimens for the treatment of advanced ICC. A phase-III, multicenter, double-blinded, randomized study to validate our findings was approved by the National Medical Products Administration (NMPA, No. 2021LP01825).Trial registration Clinical trials: NCT03951597.

RG-I Domain Matters to the In Vitro Fermentation Characteristics of Pectic Polysaccharides Recycled from Citrus Canning Processing Water.

Canned citrus is a major citrus product that is popular around the world. However, the canning process discharges large amounts of high-chemical oxygen demand wastewater, which contains many functional polysaccharides. Herein, we recovered three different pectic polysaccharides from citrus canning processing water and evaluated their prebiotic potential as well as the relationship between the RG-I domain and fermentation characteristics using an in vitro human fecal batch fermentation model. Structural analysis showed a large difference among the three pectic polysaccharides in the proportion of the rhamnogalacturonan-I (RG-I) domain. Additionally, the fermentation results showed that the RG-I domain was significantly related to pectic polysaccharides' fermentation characteristics, especially in terms of short-chain fatty acid generation and modulation of gut microbiota. The pectins with a high proportion of the RG-I domain performed better in acetate, propionate, and butyrate production. It was also found that Bacteroides, Phascolarctobacterium, and Bifidobacterium are the main bacteria participating in their degradation. Furthermore, the relative abundance of Eubacterium_eligens_group and Monoglobus was positively correlated with the proportion of the RG-I domain. This study emphasizes the beneficial effects of pectic polysaccharides recovered from citrus processing and the roles of the RG-I domain in their fermentation characteristics. This study also provides a strategy for food factories to realize green production and value addition.

An MMP-9 exclusive neutralizing antibody attenuates blood-brain barrier breakdown in mice with stroke and reduces stroke patient-derived MMP-9 activity.

Rapid upregulation of matrix metalloproteinase 9 (MMP-9) leads to blood-brain barrier (BBB) breakdown following stroke, but no MMP-9 inhibitors have been approved in clinic largely due to their low specificities and side effects. Here, we explored the therapeutic potential of a human IgG monoclonal antibody (mAb), L13, which was recently developed with exclusive neutralizing specificity to MMP-9, nanomolar potency, and biological function, using mouse stroke models and stroke patient samples. We found that L13 treatment at the onset of reperfusion following cerebral ischemia or after intracranial hemorrhage (ICH) significantly reduced brain tissue injury and improved the neurological outcomes of mice. Compared to control IgG, L13 substantially attenuated BBB breakdown in both types of stroke model by inhibiting MMP-9 activity-mediated degradations of basement membrane and endothelial tight junction proteins. Importantly, these BBB-protective and neuroprotective effects of L13 in wild-type mice were comparable to Mmp9 genetic deletion and fully abolished in Mmp9 knockout mice, highlighting the in vivo target specificity of L13. Meanwhile, ex vivo co-incubation with L13 significantly neutralized the enzymatic activities of human MMP-9 in the sera of ischemic and hemorrhagic stroke patients, or in the peri-hematoma brain tissues from hemorrhagic stroke patients. Overall, we demonstrated that MMP-9 exclusive neutralizing mAbs constitute a potential feasible therapeutic approach for both ischemic and hemorrhagic stroke.

Using the Sustainable Development Capacity of Key Counties to Guide Rural Revitalization in China.

Counties are the basic unit for addressing unbalanced development in a region, revitalizing rural areas, and promoting the integrated development of urban and rural areas. Despite the importance of county-level research, few studies have been conducted research at such a small scale. To address this gap in knowledge, this study constructs an evaluation system to measure the county sustainable development capacity (CSDC) of counties in China, identify constraints to development, and provide policy suggestions to promote the counties' long-term stable development. Specifically, the CSDC indicator system was based on the regional theory of sustainable development and included economic aggregation capacity, social development capacity, and environmental carrying capacity. This framework was applied to 103 key counties to receive assistance in pursuing rural revitalization in 10 provinces in western China. The AHP-Entropy Weighting Method and TOPSIS model were employed to inform the scores of CSDC and its secondary indicators, and ArcGIS 10.8 was used to portray the spatial distribution of CSDC and to classify these key counties into categories that guided specific policy recommendations. The results demonstrate a high degree of unbalanced and inadequate development in these counties and that rural revitalization efforts can be targeted to increase the speed of development. It is crucial to follow the recommendations that conclude this paper to promote sustainable development in areas that have been lifted out of poverty and to revive rural areas.

The effect of surface gloss on categorical color constancy in real scenes.

Categorical color constancy has been widely investigated and found to be very robust. As one of object material properties, the surface gloss was found to barely contribute to color constancy in a natural viewing condition. In this study, the effect of surface gloss on categorical color constancy was investigated by asking eight observers to categorize 208 Munsell matte surfaces and 260 Munsell glossy surfaces under D65, F, and TL84 illuminants in a viewing chamber with a uniform gray background. A color constancy index based on the centroid shift of the color category was used to evaluate color constancy degree of each color category across illumination changes from D65 to F or TL84 illuminant. The result showed that both matte and glossy surfaces showed almost perfect color constancy on all color categories under F and TL84 illuminants, and there was no significant difference between them. This result suggests that surface gloss has little effect on categorical color constancy in a uniform gray background where the local surround cue was present, which is consistent with the previous findings.

XBP1s acts as a transcription factor of IRE1α and promotes proliferation of colon cancer cells.

Upon ER stress, IRE1α is activated to splice XBP1 mRNA to generate XBP1s, a transcription factor that induces the expression of genes to cope with the stress. Expression of IRE1α is elevated in cancers and the IRE1α-XBP1s axis plays an important role in proliferation of cancer cells. However, the underlying mechanism is not well known. We found that ER stressors induced the expression of IRE1α, which was inhibited by depletion of XBP1s. XBP1s bound IRE1α promoter and initiated the transcription of IRE1α. These data indicate that XBP1s acts as a transcription factor of IRE1α. Overexpression of XBP1s increased the phosphorylation of JNK, a substrate of IRE1α kinase, which was inhibited by IRE1α kinase inhibitor Kira8. Overexpression of XBP1s also activated the regulated IRE1-dependent decay of mRNAs, which was suppressed by IRE1α RNase inhibitor STF083010. Moreover, we found that expression of XBP1s promoted proliferation of colon cancer cells, which was abrogated by Kira8 and STF083010. The results suggest that XBP1s functions to induce IRE1α expression and promote cancer cell proliferation. Our findings reveal a previously unknown mechanism of IRE1α expression by XBP1s and highlight the role of this regulation in proliferation of colon cancer cells, suggesting that IRE1α-targeting is a potential therapeutic strategy for colon cancer.

Comprehensive analysis of LILR family genes expression and tumour-infiltrating immune cells in early-stage pancreatic ductal adenocarcinoma.

Leucocyte immunoglobulin-like receptors (LILRs) are closely related to tumourigenesis, but their clinical value in early-stage pancreatic ductal adenocarcinoma (PDAC) after pancreaticoduodenectomy remains unknown. Kaplan-Meier and Cox proportional hazards regression models is used to investigate the association between LILR expression and prognosis in tumour biopsies and peripheral blood mononuclear cells. Risk score was calculated for each patient based on the prognostic model. DAVID, STRING, GeneMANIA, and GSEA were used to conduct pathway and functional analyses. The CIBERSORT algorithm is used to analyse tumour-infiltrating immune cells. Survival analysis showed that high levels of LILRA4 (p = 0.006) and LILRB4 (p = 0.04) were significantly associated with better overall survival. High levels of LILRA2 (p = 0.008) and LILRB4 (p = 0.038) were significantly associated with better relapse-free survival. JAK-STAT signalling pathway, regulation of T cell activation, regulation of the immune effector process, and tumour necrosis factor superfamily cytokine production were involved in molecular mechanisms that affected poor prognoses in the high-risk group in GSEA. CIBERSORT demonstrated that the high-risk group had significantly higher infiltrating fraction of memory-activated CD4 T cells and activated NK cells and lower fraction of resting dendritic cells and neutrophils. LILRB4 plays crucial roles in affecting the clinical outcomes of early-stage PDAC.

A severe complication of J-tip guide wire during catheterization: A case report and discussion.

J-tip guide wire entrapment within the heart is a serious and dangerous complication that is rarely mentioned. We present a case in which the J-tip guide wire was entrapped in the right atrium during tunneled cuffed venous catheterization. We were unable to remove the guide wire using previously reported methods and concluded with surgery. Owing to the special structure of the guide wire itself, a safe removal process needs to be discussed. Patient consent for publication was obtained prior to the submission of the manuscript.

Substituting inert phosphate with redox-active silicate towards advanced polyanion-type cathode materials for sodium-ion batteries.

Polyanion-type phosphate materials with Na-super-ionic conductor structures are promising for next-generation sodium-ion battery cathodes, although the intrinsically low electroconductivity and limited energy density have restricted their practical applications. In this study, we put forward substituting an inert phosphate with a redox-active silicate to improve the energy density and intrinsic electroconductivity of polyanion-type phosphate materials, thus enabling an advance in sodium-ion battery cathodes. As a proof of concept, some of the phosphate of Na3V2(PO4)3 was replaced by silicate to fabricate Na3V2(PO4)2.9(SiO4)0.1, which exhibited a higher average discharge voltage of 3.36 V and a higher capacity of 115.8 mA h g-1 than pristine Na3V2(PO4)3 (3.31 V, 109.6 mA h g-1) at 0.5 C, therefore improving the energy density. Moreover, the introduced silicate enhanced the intrinsic electroconductivity of Na3V2(PO4)3 materials, as confirmed by both theoretical simulation and electrochemical measurements. After pairing with a commercial hard carbon anode, the optimized Na3V2(PO4)2.9(SiO4)0.1 cathode enabled a stable-cycling full cell with 90.1% capacity retention after 300 cycles at 5 C and a remarkable average coulombic efficiency of 99.88%.

Design and Implementation of a Chain-Type Direct Push Drilling Rig for Contaminated Sites.

For sites where volatile organic compounds are present, the direct push method, in combination with other sensors for investigation, is a powerful method. The investigation process is an integrated drilling and sensing process, but the trajectory of the probe carrying the sensor is ambiguous. This paper explores and introduces the application of a chain-type direct push drilling rig by designing and building a chain-type direct push miniature drilling rig. This rig allows for indoor experimental studies of direct push trajectories. The chain-type direct push drilling model is proposed based on the mechanism of chain transmission. The drilling rig provides a steady direct thrust through the chain, which is driven by a hydraulic motor. In addition, the drilling tests and results described prove that the chain could be applied to direct push drilling. The chain-type direct push drilling rig can drill to a depth of 1940 mm in single-pass and up to 20,000 mm in multiple passes. The test results also indicate that it drills a total length of 462.461 mm and stops after 87.545 s of operation. The machine can provide a drilling angle of 0-90° and keep the borehole angle fluctuating within 0.6° with the characteristics of strong adjustability, flexibility, continuity, stability, and low disturbance, which is of great value and significance for studying the drilling trajectory of direct push tools and obtaining more accurate investigation data.

Compressive Properties and Energy Absorption Behavior of 316L Steel Foam Prepared by Space Holder Technique.

The effect of porosity and pore size on the quasi-static compression properties and energy absorption characteristics of the steel foam was investigated in this paper. The 316L steel foams were prepared through powder metallurgy using urea as the space holder. The macrostructure of steel foam and microstructure of the pore walls were characterized, and the quasi-static compression experiments were conducted on the specimens in the axial direction at a strain rate of 10-3 s-1. The results show that the increase in porosity decreases the yield strength and plastic modulus of the steel foam but increases the densification strain of the steel foam. The yield strength of the steel foam decreases significantly when the pore size is 2.37 mm. However, the pore size has little effect on the plastic modulus. Moreover, the energy absorption per volume of the steel foam decreases with increasing porosity at the same strain. The effect of porosity on energy absorption efficiency is greater than that of pore size.