TRIM26 deficiency enhancing liver regeneration through macrophage polarization and ß-catenin pathway activation.

Liver regeneration is a complex process involving the crosstalk between parenchymal and non-parenchymal cells, especially macrophages. However, the underlying mechanisms remain incompletely understood. Here, we identify the E3 ubiquitin ligase TRIM26 as a crucial regulator of liver regeneration. Following partial hepatectomy or acute liver injury induced by carbon tetrachloride, Trim26 knockout mice exhibit enhanced hepatocyte proliferation compared to wild-type controls, while adeno-associated virus (AAV)-mediated overexpression of Trim26 reverses the promotional effects. Mechanistically, Trim26 deficiency promotes the recruitment of macrophages to the liver and their polarization towards pro-inflammatory M1 phenotype. These M1 macrophages secrete Wnts, including Wnt2, which subsequently stimulate hepatocyte proliferation through the activation of Wnt/ß-catenin signaling. In hepatocytes, Trim26 knockdown reduces the ubiquitination and degradation of ß-catenin, thereby further enhancing Wnt/ß-catenin signaling. Pharmacological inhibition of Wnt/ß-catenin pathway by ICG-001 or depletion of macrophages by clodronate liposomes diminishes the pro-regenerative effects of Trim26 deficiency. Moreover, bone marrow transplantation experiments provide evidence that Trim26 knockout in myeloid cells alone can also promote liver regeneration, highlighting the critical role of macrophage Trim26 in this process. Taken together, our study uncovers TRIM26 as a negative regulator of liver regeneration by modulating macrophage polarization and Wnt/ß-catenin signaling in hepatocytes, providing a potential therapeutic target for promoting liver regeneration in clinical settings.

A Surface Electromyography (sEMG) System Applied for Grip Force Monitoring.

Muscles play an indispensable role in human life. Surface electromyography (sEMG), as a non-invasive method, is crucial for monitoring muscle status. It is characterized by its real-time, portable nature and is extensively utilized in sports and rehabilitation sciences. This study proposed a wireless acquisition system based on multi-channel sEMG for objective monitoring of grip force. The system consists of an sEMG acquisition module containing four-channel discrete terminals and a host computer receiver module, using Bluetooth wireless transmission. The system is portable, wearable, low-cost, and easy to operate. Leveraging the system, an experiment for grip force prediction was designed, employing the bald eagle search (BES) algorithm to enhance the Random Forest (RF) algorithm. This approach established a grip force prediction model based on dual-channel sEMG signals. As tested, the performance of acquisition terminal proceeded as follows: the gain was up to 1125 times, and the common mode rejection ratio (CMRR) remained high in the sEMG signal band range (96.94 dB (100 Hz), 84.12 dB (500 Hz)), while the performance of the grip force prediction algorithm had an R2 of 0.9215, an MAE of 1.0637, and an MSE of 1.7479. The proposed system demonstrates excellent performance in real-time signal acquisition and grip force prediction, proving to be an effective muscle status monitoring tool for rehabilitation, training, disease condition surveillance and scientific fitness applications.

Cardiac Multi-Frequency Vibration Signal Sensor Module and Feature Extraction Method Based on Vibration Modeling.

Cardiovascular diseases pose a long-term risk to human health. This study focuses on the rich-spectrum mechanical vibrations generated during cardiac activity. By combining Fourier series theory, we propose a multi-frequency vibration model for the heart, decomposing cardiac vibration into frequency bands and establishing a systematic interpretation for detecting multi-frequency cardiac vibrations. Based on this, we develop a small multi-frequency vibration sensor module based on flexible polyvinylidene fluoride (PVDF) films, which is capable of synchronously collecting ultra-low-frequency seismocardiography (ULF-SCG), seismocardiography (SCG), and phonocardiography (PCG) signals with high sensitivity. Comparative experiments validate the sensor's performance and we further develop an algorithm framework for feature extraction based on 1D-CNN models, achieving continuous recognition of multiple vibration features. Testing shows that the recognition coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE) of the 8 features are 0.95, 2.18 ms, and 4.89 ms, respectively, with an average prediction speed of 60.18 us/point, meeting the re-quirements for online monitoring while ensuring accuracy in extracting multiple feature points. Finally, integrating the vibration model, sensor, and feature extraction algorithm, we propose a dynamic monitoring system for multi-frequency cardiac vibration, which can be applied to portable monitoring devices for daily dynamic cardiac monitoring, providing a new approach for the early diagnosis and prevention of cardiovascular diseases.

A Portable Cardiac Dynamic Monitoring System in the Framework of Electro-Mechano-Acoustic Mapping.

Abnormalities in cardiac function arise irregularly and typically involve multimodal electrical, mechanical vibrations, and acoustics alterations. This paper proposes an Electro-Mechano-Acoustic (EMA) activity model for mapping the complete macroscopic cardiac function to refine the systematic interpretation of cardiac multimodal assessment. We abstract this activity pattern and build the mapping system by analyzing the functional comparison of the heart pump and Electronic Fuel Injection (EFI) system from the multimodal characteristics of the heart. Electrocardiogram (ECG), seismocardiogram (SCG) & Ultra-Low Frequency seismocardiogram (ULF-SCG), and Phonocardiogram (PCG) are selected to implement the EMA mapping respectively. First, a novel low-frequency cardiograph compound sensor capable of extracting both SCG and ULF-SCG is proposed, which is integrated with ECG and PCG modules on a single hardware device for portable dynamic acquisition. Afterward, a multimodal signal processing chain further analyses the acquired synchronized signals, and the extracted ULF-SCG is shown to indicate changes in heart volume. In particular, the proposed method based on waveform curvature is used to extract 9 feature points of the SCG signal, and the overall recognition accuracy reaches over 90% in the data collected by EMA portable device. Ultimately, we integrate the portable device and signal processing chains to form the EMA cardiovascular mapping system (EMACMS). As a next-generation system solution for cardiac daily dynamic monitoring, which can map the mechanical coupling and electromechanical coupling process, extract multi-characteristic heart rate variability (HRV), and enable extraction of important time intervals of cardiac activity to assess cardiac function.

Bioactive glass in the treatment of ulcerative colitis to regulate the TLR4 / MyD88 / NF-κB pathway.

Ulcerative colitis (UC) is a chronic and recurrent intestinal disease of unknown aetiology, and the few treatments approved for UC have serious side effects. In this study, a new type of uniformly monodispersed calcium-enhanced radial mesoporous micro-nano bioactive glass (HCa-MBG) was prepared for UC treatment. We established cellular and rat UC models to explore the effects and mechanism of HCa-MBG and traditional BGs (45S5, 58S) on UC. The results showed that BGs significantly reduced the cellular expression of several inflammatory factors, such as IL-1ß, IL-6, TNF-α and NO. In the animal experiments, BGs were shown to repair the DSS-damaged colonic mucosa. Moreover, BGs downregulated the mRNA levels of the inflammatory factors IL-1ß, IL-6, TNF-α and iNOS, which were stimulated by DSS. BGs were also found to manage the expression of key proteins in NF-kB signal pathway. However, HCa-MBG was more effective than traditional BGs in terms of improving UC clinical manifestations and reducing the expression of inflammatory factors in rats. This study confirmed for the first time that BGs can be used as an adjuvant drug in UC treatment, thereby preventing UC progression.

Development of receptor binding domain-based double-antigen sandwich lateral flow immunoassay for the detection and evaluation of SARS-CoV-2 neutralizing antibody in clinical sera samples compared with the conventional virus neutralization test.

Vaccination is an effective strategy to fight COVID-19. However, the effectiveness of the vaccine varies among different populations in varying immune effects. Neutralizing antibody (NAb) level is an important indicator to evaluate the protective effect of immune response after vaccination. Lateral flow immunoassay (LFIA) is a rapid, safe and sensitivity detection method, which has great potential in the detection of SARS-CoV-2 NAb. In this study, a fluorescent beads-based lateral flow immunoassay (FBs-LFIA) and a latex beads-based LFIA (LBs-LFIA) using double antigen sandwich (DAS) strategy were established to detect NAbs in the serum of vaccinated people. The limit of detection (LoD) of the FBs-LFIA was 1.13 ng mL- 1 and the LBs-LFIA was 7.11 ng mL- 1. The two LFIAs were no cross-reactive with sera infected by other pathogenic bacteria. Furthermore, the two LFIAs showed a good performance in testing clinical samples. The sensitivity of FBs-LFIA and LBs-LFIA were 97.44% (95%CI: 93.15%-99.18%) and 98.29% (95%CI: 95.84%-99.37%), and the specificity were 98.28% (95%CI: 95.37%-99.45%) and 97.70% (95%CI: 94.82%-99.06%) compared with the conventional virus neutralization test (cVNT), respectively. Notably, the LBs-LFIA was also suitable for whole blood sample, requiring only 3 µL of whole blood, which provided the possibility to detect NAbs at home. To sum up, the two LFIAs based on double antigen sandwich established by us can rapidly, safely, sensitively and accurately detect SARS-CoV-2 NAb in human serum.

Combined laparoscopic-endoscopic approach for gastric glomus tumor: A case report.

BACKGROUND: Gastric glomus tumor (GGT) is rare submucosal mesenchymal tumor that lacks specific clinical manifestations and is usually treated mainly by traditional surgical resection. This paper presents a case of a GGT, exhibited both intraluminally and extraluminally growth that was removed by laparoscopy-gastroscopy cooperative surgery. CASE SUMMARY: A 52-year-old male presented with epigastric discomfort accompanied by a sense of fullness for 3 mo. Upper gastrointestinal endoscopy identified a submucosal lump located in the gastric antrum. Endoscopic ultrasonography identified a 2.4 cm × 1.8 cm lump located in the gastric antrum. It originated from the muscularis propria and exhibited both intraluminally and extraluminally growth, with hypoechoicity on the periphery, hyperechoicity in the middle, and unclear boundaries. Computed tomography showed nodular thickening of 3.0 cm × 2.2 cm in the gastric wall of the gastric antrum, and after enhancement, the lesion exhibited obvious enhancement We suspected that it was a gastrointestinal stromal tumor (glomus tumor and schwannoma were not excluded) and planned to perform laparoscopy-gastroscopy cooperative surgery. Immunohistochemical staining after the operation revealed that spinal muscular atrophy (+), h-caldesmon (+), cluster of differentiation 34 (CD34) (+), 2% Ki-67-positive rate, CD56, melanoma antigen, CD117, discovered on GIST-1, leukocyte common antigen, caudal type homeobox 2, cytokeratin, and S-100 were all negative. The tumor was finally diagnosed as a GGT. CONCLUSION: GGTs are rare submucosal tumors of the stomach and should be considered in the differential diagnosis of gastric submucosal tumors. Laparoscopy-gastroscopy cooperative surgery is less invasive and more precise and could be an effective method for the treatment of GGTs.

[Corrigendum] Synergic effect between 5­fluorouracil and celecoxib on hypoxic gastric cancer cells.

Following the publication of the above article, the authors have realized that Fig. 2 was published with an incorrect data panel: Essentially, Fig. 2D was erroneously selected from the representative images of the Fig. 1C data group during figure compilation. The authors were able to locate their original data, and the corrected version of Fig. 2, featuring the corrected data panel for Fig. 2D, is shown below. All the authors agree with this Corrigendum, and are grateful to the Editor of Molecular Medicine Reports for allowing them to publish it. The authors also regret that this inadvertent error was included in the paper, even though it did not substantially alter any of the major conclusions reported in the study, and apologize to the readership for any inconvenience caused. [the original article was published in Molecular Medicine Reports 11: 1160­1166, 2014; DOI: 10.3892/mmr.2014.2783].

Inhibition of protein FAK enhances 5-FU chemosensitivity to gastric carcinoma via p53 signaling pathways.

The small molecule drug 5-fluorouracil (5-FU) is widely used in the treatment for gastric cancer (GC), however, it exerts poor efficacy and is associated with acquired and intrinsic resistance. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays a key role in adhesion, migration, and proliferation of gastric carcinoma cells, suggesting that this kinase may be a promising therapeutic target. Differentially expressed FAK in GC tissue was detected by RT-qPCR and TCGA database analysis. To investigate the biological functions of FAK, loss-of-function experiments were performed. CCK-8 assay, colony formation assay, flow cytometry, dual-luciferase reporter assays, and western blot assays were conducted to determine the underlying mechanisms of FAK in 5-FU chemosensitivity in GC. FAK is overexpressed in GC patients, and positively correlated with poor prognosis. The use of shRNA interference to target FAK decreased proliferation and increased apoptosis of GC cells in vitro. Importantly, FAK silencing enhanced the therapeutic efficacy of 5-FU, leading to reduced tumor growth in vivo. We further demonstrated that FAK silencing increased 5-FU-induced caspase-3 activity, and promoted p53 transcriptional activities. Clinical data also has shown that patients with higher levels of FAK had significantly shorter overall survival (OS) and time to first progression (FP) than those with lower levels of FAK. These findings indicate that FAK plays a critical role in 5-FU chemosensitivity in GC, and the use of FAK inhibitors as an adjunct to 5-FU might be an effective strategy for patients who undergo chemotherapy.

Effect of p53ß on human gastric cancer cells treated with recombinant mutated human TNF and cisplatin.

The present study aimed to investigate the role of tumour protein 53 isoform b (p53ß) on human gastric cancer (GC) cell lines treated with recombinant mutated human tumour necrosis factor (rmhTNF) and cisplatin. The Cell Counting Kit­8 assay was used to assess growth in the GC cell lines MKN45 and SGC7901, following treatment with rmhTNF in the presence or absence of cisplatin. Levels of p53ß and bcl­2 apoptosis regulator (bcl­2) mRNA were assessed using reverse transcription­polymerase chain reaction. The results demonstrated that growth was significantly inhibited by either cisplatin or rmhTNF treatments alone in MKN45 cells, and combination treatment with cisplatin and rmhTNF had a synergistic effect on growth inhibition of MKN45 cells. Notably, these observations were not evident in SGC7901 cells, where a mutant form of p53 is present. Treatment of MKN45 cells with rmhTNF did not affect bcl­2 or p53ß mRNA expression levels. However, treatment of MKN45 cells with cisplatin induced upregulation of p53ß and downregulation of bcl-2 mRNA expression levels, and these effects were enhanced by combination treatment with rmhTNF. Pearson correlation analysis revealed a negative correlation between the expression of p53ß and bcl­2 mRNA, and a negative correlation between bcl-2 mRNA expression and the inhibition of cell growth. In conclusion, the inhibitory effect of cisplatin on the growth of MKN45 GC cells was enhanced by rmhTNF via unknown mechanisms that involved p53ß, indicating that p53ß may be an appropriate therapeutic target for the treatment of GC.

Expression of p53ß and Δ133p53 isoforms in different gastric tissues.

This study aims to detect the mRNA of p53ß and Δ133p53 isoforms in three gastric carcinoma cell lines and tissues of superficial gastritis, atrophic gastritis, gastric carcinoma, or paracancerous area. Nested reverse transcription PCR was used to detect the mRNA of p53ß and Δ133p53 isoforms in tissues of superficial gastritis, chronic atrophic gastritis, gastric cancer cell lines (SGC-7901, MKN45, KATO III), gastric adenocarcinoma, and paracancerous lesion. The amplified products were shown by agarose gel electrophoresis. The expression difference among various tissues was analyzed by x(2) tests. The positive rates of ∆133p53 mRNA were 73.3% (11/15) in gastric adenocarcinoma and 20% (3/15) in paracancerous tissue, whereas the positive rates of p53ß mRNA were 20% (3/15) in gastric adenocarcinoma and 66.7% (10/15) in paracancerous tissue. The difference between adenocarcinoma and paracancerous tissues was significant (P<0.05). The positive rates of ∆133p53 mRNA were 25% (5/20), 50% (15/30), and 75% (15/20), respectively, in superficial gastritis, atrophic gastritis, and gastric adenocarcinoma; the positive rates of p53ß mRNA were 65% (13/20), 33.3% (10/30), and 25% (5/20), respectively, in superficial gastritis, atrophic gastritis, and gastric adenocarcinoma. The difference between adenocarcinoma and superficial gastritis samples was significant (P<0.05). Both p53ß and ∆133p53 mRNAs were positive in MKN45; only p53ß mRNA was detected in SGC7901; neither p53ß nor ∆133p53 mRNA was detected in KATO III. ∆133p53 and p53ß, which are possible indicators for the diagnosis and biological therapy of gastric carcinoma, were expressed differentially in different gastric tissues.

Role of p53ß in the inhibition of proliferation of gastric cancer cells expressing wild-type or mutated p53.

p53 is a tumor suppressor gene whose mutation is highly associated with tumorigenesis. The present study investigated the role of p53ß in the inhibition of proliferation of gastric cancer cell lines expressing wild-type or mutated p53. Wild-type p53 is expressed in MKN45 cells, but deleted in KATOIII cells, whereas mutated p53 is expressed in SGC7901 cells. The mRNA expression levels of p53ß and Δ133p53 were detected in MKN45, SGC-7901 and KATOIII gastric cancer cell lines using nested polymerase chain reaction (PCR). The mRNA expression levels of p53, p53ß and B-cell lymphoma 2-associated X protein (Bax) were detected in the MKN45 and SGC-7901 cells following treatment with cisplatin by reverse transcription-PCR. The inhibition of cellular proliferation following treatment with cisplatin was measured by MTT assay. The results of the present study demonstrated that both p53ß and Δ133p53 mRNA were expressed in the MKN45 cells, whereas only p53ß mRNA was expressed in the SGC7901 cells. No expression of p53ß or Δ133p53 mRNA was detected in the KATOIII cells. Following treatment with cisplatin, the number of both MKN45 and SGC-7901 cells was significantly reduced (P<0.001). In the MKN45 cells, p53ß, p53 and Bax mRNA expression levels gradually increased with the dose of cisplatin, and the expression of p53ß was positively correlated with the expression of p53 (tr=6.358, P<0.05) and Bax (tr=8.023, P<0.05). In the SGC-7901 cells, the expression levels of p53ß, p53 and Bax mRNA did not alter with the dose of cisplatin, and the expression of p53ß was positively correlated to the expression of p53 (tr=26.41, P<0.01) but not that of Bax. The present study identified the different roles of the p53ß isoform in gastric cancer cells with different p53 backgrounds. Enhanced knowledge regarding the p53 status is required for the development of specific biological therapies against gastric cancer.

Synergic effect between 5­fluorouracil and celecoxib on hypoxic gastric cancer cells.

5­fluorouracil (5­FU) is commonly used in the treatment of gastric cancer; however, resistance to this drug occurs under hypoxic conditions. Celecoxib may be used to reverse this resistance. The aim of the present study was to elucidate the inhibitory effects and mechanisms of 5­FU and celecoxib on the gastric cancer cell line SGC7901 under hypoxic conditions. SGC7901 cells were divided into four groups: Hypoxic control group, 5­FU group, celecoxib group and 5­FU/celecoxib combination group. Following treatment, the inhibition rates of cells were determined using an MTT assay. Protein and messenger RNA (mRNA) expression of hypoxia­inducible factor 2α (HIF­2α), adenosine triphosphate­binding cassette sub­family G member 2 (ABCG2) and octamer binding protein 4 (Oct­4) were determined using immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT­qPCR) and western blot analysis. The results demonstrated that the 5­FU/celecoxib combination group had a significantly higher inhibition rate than the individually treated 5­FU and celecoxib groups (P<0.05); inhibition rates were 66.09, 52.61 and 46.1%, respectively. mRNA and protein expression levels of HIF­2α, ABCG2 and Oct­4 were significantly lower in the celecoxib and 5­FU/celecoxib combination groups (P<0.01) compared with those of the hypoxia control and 5­FU groups. The 5­FU group demonstrated the highest levels of the respective mRNA and proteins. In conclusion, the results of the present study indicated that celecoxib had anti­tumor effects, as it was shown to inhibit tumor cell growth via the inhibition of HIF­2α, ABCG2 and Oct­4. The 5­FU/celecoxib combination had a synergic effect on tumor growth inhibition. This therefore suggested that inhibition of HIF­2α, ABCG2 and Oct­4 may be a potential method of reducing chemotherapy resistance and enhancing the effectiveness of chemotherapy treatment.

Purification and characterization of trypsin from the intestine of hybrid tilapia (Oreochromis niloticusxO.aureus).

Trypsin from the intestine of hybrid tilapia (Oreochromis niloticus x O.aureus) was purified by the following techniques: acetone precipitation, ammonium sulfate fractionation, Sephacryl S-200 gel filtration, and DEAE-sephacel ion exchange chromatography. The purified enzyme was determined to be homogeneous by polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE. The molecular weight was estimated as 22,000 Da. The optimum pH and temperature of the enzyme for the hydrolysis of casein were determined to be 9.0 and 60 degrees C, respectively. The enzyme was stable over a broad pH range from 7.0 to 12.0 at 30 degrees C, and the enzyme was inactive at temperatures above 50 degrees C. The behavior of the enzyme for the hydrolysis of casein followed Michaelis-Menten kinetics with Km of 0.46 mg/mL. The purified enzyme was inhibited by the general serine protease inhibitor phenyl methyl sulphonyl fluoride (PMSF) and also by the specific trypsin inhibitor N-p-tosyl-L-lysine chloromethyl ketone (TLCK) using Nalpha-CBZ-L-lysine p-nitrophenyl ester hydrochloride (CBZ-Lys.pNP) as a substrate. The protease was inhibited by the following ions in decreasing order: Zn2+>Fe3+>Cu2+>Al3+>Co2+=Pb2+>Cd2+>Mn2+. The ions Li+, Na+, K+, Mg2+, and Ba2+ had little effect on the enzyme, and Ca2+ can partially promote its activity at low concentration.

Effect of Hewei-Decoction on chronic atrophic gastritis and eradication of Helicobacter pylori.

AIM: To demonstrate the effect of Hewei-Decoction (Decoction for regulating the stomach) on chronic atrophic gastritis (CAG) and eradication of Helicobacter pylori. METHODS: Ninety patients with CAG entering the investigation were divided into six differentiation syndromes, based on their major symptoms and signs. Hewei-Decoction was taken by all the patients orally for 4 or 8 wk. The efficacy was assessed by both the composite accumulation of reduced scores of major symptoms and the eradication of H pylori. chi(2) test was used to compare the efficacy between H pylori-positive and negative cases, and to disclose the relationship between efficacy and eradication of H pylori. RESULTS: In patients with six different syndrome types, the efficacy of Hewei-Decoction was 91.67% (11/12), 92.86% (13/14), 97.22% (35/36), 87.50% (14/16), 75.00% (6/8), 75.00% (3/4) respectively. The rate of highly efficacious was 58.33% (7/12), 50.00% (7/14), 77.78% (28/36), 62.50% (10/16), 12.50% (1/8) and 25.00% (1/4), respectively. The total efficacy was 91.11% (82/90), and the rate of highly efficacious was 60.00% (54/90). The eradication rate of H pylori was 67.86% (38/56). The therapeutic effect of Hewei-Decoction was better in H pylori positive cases than that in H pylori-negative cases with the total effect of 96.43% vs 82.35% (P<0.05). In 56 H pylori positive cases, the therapeutic effect was better in H pylori eradicated cases than that in H pylori- existent cases with the total effect of 97.37% vs 72.22% (P<0.01). CONCLUSION: Hewei-Decoction is effective in most cases of all the syndrome types. The results indicate that eradication of H pylori is one of the important mechanisms for alleviation of symptoms and signs. Also, the decoction is efficacious in H pylori-negative cases.

Effect of rat Schwann cell secretion on proliferation and differentiation of human neural stem cells.

OBJECTIVE: To investigate the effect of rat Schwann cell secretion on the proliferation and differentiation of human embryonic neural stem cells (NSCs). METHODS: The samples were divided into three groups. In Group One, NSCs were cultured in DMED/F12 in which Schwann cells had grown for one day. In Group Two, NSCs and Schwann cells were co-cultured. In Group Three, NSCs were cultured in DMEM/F12. The morphology of NSCs was checked and beta-tubulin, GalC, hoechst 33342 and GFAP labellings were detected. RESULTS: In Group One, all neural spheres were attached to the bottom and differentiated. The majority of them were beta-tubulin positive while a few of cells were GFAP or GalC positive. In Group Two, neural spheres remained undifferentiated and their proliferation was inhibited in places where Schwann cells were robust. In places where there were few Schwann cells, NSCs performed in a similar manner as in Group One. In Group Three, the cell growth state deteriorated day after day. On the 7th day, most NSCs died. CONCLUSION: The secretion of rat Schwann cells has a growth supportive and differentiation-inducing effect on human NSCs.