ObjectiveTo investigate the possible mechanism of Jishe Qushi Capsule （脊蛇祛湿胶囊， JQC） in treating rheumatoid arthritis （RA） from the perspective of macrophage polarization mediated by neutrophil extracellular traps （NETs）. MethodsTwenty-four female SD rats were randomly divided into four groups， blank control group， model group， JQC group， and peptidylarginine deiminase 4 （PAD4） inhibitor group with 6 rats in each group. All groups but the blank control group were subjected to the induction of collagen-induced arthritis （CIA）. After successful model establishment， rats in the JQC group received intragastric administration of JQC 1.47 g/kg daily； rats in the PAD4 inhibitor group received intraperitoneal injections of the PAD4 inhibitor 4 mg/kg weekly. Rats in the blank， model， and PAD4 inhibitor groups received 2 ml of pure water daily by gavage. All treatments lasted 4 weeks. Joint lesions of each group were assessed on day 7， 14， 21， 28， and 35 after model establishment， and arthritis index （AI） scores were recorded. At 24 h after the final administration， histopathology of knee joints， including HE staining， safranin O-fast green staining， and TRAP staining， was performed. Flow cytometry was used to detect the counts of M1 and M2 macrophages in peripheral blood. ELISA was used to determine serum levels of TRACP， NETs， TNF-α， IL-1β， and iNOS. Western Blotting and qRT-PCR were used to measure MPO， NE， RANKL， OPG， and p65 protein and mRNA expression in knee cartilage tissue. ResultsCompared with the blank control group， the model group showed increased AI scores （P＜0.05）， marked synovial inflammatory infiltration， angiogenesis， and bone-cartilage destruction， increased TRAP-positive osteoclasts， increased M1 macrophages and decreased M2 macrophages， elevated serum TRACP， NETs， TNF-α， IL-1β， and iNOS （P＜0.05）， elevated MPO， NE， RANKL， and p65 protein/mRNA expression and decreased OPG protein/mRNA expression in knee cartilage tissue （P＜0.05）. Compared with the model group， the JQC group exhibited improved synovial inflammation， angiogenesis， and bone-cartilage damage， reduced AI scores on day 21， 28， and 35， decreased osteoclast counts， decreased M1 macrophages and increased M2 macrophages， reduced serum TRACP， NETs， TNF-α， IL-1β， and iNOS （P＜0.05）， decreased MPO， NE， RANKL， and p65 protein/mRNA expression and increased OPG expression （P＜0.05）. Compared with the PAD4 inhibitor group， the JQC group showed significantly lower AI scores， reduced M1 macrophages， increased M2 macrophages （P＜0.05）， reduced serum TRACP， TNF-α， IL-1β， and iNOS， decreased MPO， RANKL， and p65 expression， and increased OPG levels （P＜0.05）. ConclusionThe therapeutic mechanism of JQC for RA may involve inhibition of NETs formation， downregulation of the RANKL/NF-κB signaling pathway， and regulation of macrophage M1/M2 polarization imbalance， thereby suppressing osteoclastogenesis and inflammatory bone destruction.

OBJECTIVE: To elucidate the role and underlying mechanism of ubiquitin-specific protease 35 (USP35) in ferroptosis of rheumatoid arthritis-fibroblast like synoviocytes (RA-FLS), thereby enhancing our comprehension of the pathogenesis of RA and identifying potential therapeutic targets for its treatment. METHODS: (1) RA-FLS were cultured in vitro and transduced with lentiviral vectors to establish stable cell lines: A USP35-knockdown line (short hairpin ribonucleic acid of USP35, shUSP35) and its control (negtive control of short hairpin ribonucleic acid, shNC), as well as a overexpression of USP35 line (USP35 OE) and its control (Vector). To investigate the role of USP35 in ferroptosis regulation, a ferroptosis model was induced in RA-FLS by treatment with 1 μmol/L Erastin. The cells were divided into six groups: shNC, shNC + Erastin, shUSP35 + Erastin, Vector, Vector + Erastin, and USP35 OE + Erastin. (2) Cell viability was detected using the cell counting kit-8 (CCK-8). (3) Reactive oxygen species (ROS), malondialdehyde (MDA), glutathione/glutathione disulfide (GSH/GSSG) ratios, and Ferrous ion (Fe²⁺) levels were measured using specific assay kits to evaluate oxidative stress, lipid peroxidation, and glutathione redox status in the cells. (4) Protein expression levels of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) were detected using Western blotting to investigate their potential involvement in USP35-mediated ferroptosis regulation. RESULTS: (1) Compared with the shNC +Erastin group, the cell viability of the shUSP35+Erastin group was significantly decreased (P < 0.001), while it was notably increased in the USP35 OE+Erastin group compared with the Vector+Erastin group (P < 0.001). These findings indicated that USP35 could alleviate the inhibitory effect of Erastin on RA-FLS cell viability. (2) In comparison to the shNC+Erastin group, the levels of ROS (P < 0.001), MDA (P < 0.05), and Fe²⁺ (P < 0.001) were significantly elevated, and the GSH/GSSG ratio was increased (P < 0.05) in the shUSP35+Erastin group. Conversely, the levels of ROS (P < 0.001), MDA (P < 0.05), and Fe²⁺ (P < 0.05) were significantly decreased, and the GSH/GSSG ratio was decreased (P < 0.05) in the USP35 OE+Erastin group compared with the Vector+Erastin group. These results suggested that USP35 could inhibit Erastin-induced oxidative stress and lipid peroxidation in RA-FLS. (3) In Erastin-induced RA-FLS, the expression of USP35 was positively correlated with the protein levels of SLC7A11 and GPX4, indicating a potential mechanism by which USP35 regulated ferroptosis in these cells. CONCLUSION USP35 inhibits ferroptosis in RA-FLS, potentially through the increased expression of SLC7A11 and GPX4.
Ferroptosis ; Humans ; Arthritis, Rheumatoid/metabolism* ; Synoviocytes/pathology* ; Reactive Oxygen Species/metabolism* ; Ubiquitin-Specific Proteases/metabolism* ; Fibroblasts/pathology* ; Cell Survival ; Piperazines/pharmacology* ; Endopeptidases/metabolism* ; Cells, Cultured ; Cell Line ; Amino Acid Transport System y+

Objective:To investigate the clinical characteristics of hospital-acquired pulmonary embolism(HA-PE) and identify the risk factors associated with in-hospital mortality.Methods:The retrospective cohort study was used. The clinical and follow-up data were collected of 60 patients with primary diseases who were admitted to the General Surgery Ward of Beijing Friendship Hospital affiliated to Capital Medical University from January 2015 to December 2021. These patients were planned for surgical treatment and were diagnosed with HA-PE during their hospitalization. A total of 60 patients were included in the study, comprising 18 males and 42 females.The age was (69.7±10.9)years, ranging from 45 to 91 years. Baseline clinical parameters were collected and recorded. Measurement data with normal distribution were expressed as mean ± standard deviation ( ± s), measurement data with skewed distribution were expressed as M( Q1, Q3), and count data were expressed as examples and percentages(%). Univariate Logistic regression analysis was used to screen out the risk factors related to in-hospital PE mortality, and multivariate logistic regression model was used to analyze the independent risk factors related to death of HA-PE patients. Results:Fourteen patients did not undergo surgery for primary disease due to HA-PE, the time from admission to HA-PE diagnosis was 7.0(4.0, 10.0) days. 20 patients were underwent implantation of an inferior vena cava filter, all filters used were retrievable. Successful removal of filters was achieved in 10 patients, the duration of filter placement was recorded as (19.6±3.4) days. All patients had high-risk sPESI scores, and 6 patients died from HA-PE during their hospitalization period. Multivariate analysis revealed that symptoms such as chest tightness and dyspnea ( OR=1.83, 95% CI: 1.45-10.15, P=0.039); Elevated TNI levels( OR=1.75, 95% CI: 1.46-7.78, P=0.036) and severe thrombocytopenia ( OR=3.6, 95% CI: 2.46-6.06, P=0.009) were independently correlated with in-hospital PE mortality. Conclusions:The in-hospital mortality rate of HA-PE patients is comparable to primary pulmonary embolism. Following standardized treatment, both the recurrence and mortality rates of pulmonary embolism within one year are significantly reduced. Notably, chest tightness and dyspnea, elevated TNI levels, and severe thrombocytopenia are independent risk factors for in-hospital mortality in HA-PE patients.

ObjectiveTo evaluate the efficacy and safety of transcutaneous electrical acupoint stimulation (TEAS) for muscle atrophy in patients with immobilization after surgical fixation of foot and ankle fractures.MethodsThis was a two-arm randomized controlled trial wherein 80 patients were recruited and divided into control (n = 40) and intervention (n = 40) groups. The control group received conventional orthopedic treatment, whereas the intervention group received TEAS and conventional treatment. The intervention group received TEAS 3 times a week for 30 min each time for 8 weeks. The primary outcomes were muscle thickness (MT) and cross-sectional area (CSA) of the rectus femoris and gastrocnemius muscles, whereas the secondary outcome measure was echo intensity (EI). Data were collected before the fixation operations (baseline assessment) and 4 and 8 weeks after intervention.ResultsCompared with baseline, the MT and CSA were reduced in both groups by the end of treatment, whereas EI increased in both groups. At week 4, the reduction in the rectus femoris CSA in the intervention group was significantly lower than that in the control group (P = .02); however, the between-group differences in the MT and EI (all P .05) were not significant. No serious adverse events were observed in either group.ConclusionOur study showed that TEAS can improve muscle atrophy by attenuating the decline in the muscle CSA. Because this was only a pilot trial, subsequent studies will need longer follow-ups and larger sample sizes.

BACKGROUND:Previous animal studies have shown that riluzole can inhibit neuroinflammatory response after spinal cord injury and promote functional recovery in injured rats,but the study on whether it can regulate the expression of nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome in the acute stage is lacking. OBJECTIVE:To observe whether riluzole can reduce microglial pyroptosis and promote functional recovery after spinal cord injury by modulating NLRP3 inflammasome through animal experiments,histological experiments and molecular biology experiments. METHODS:Female SD rats were divided into sham operation,model and riluzole groups,with 12 rats in each group.In addition to the sham operation group,T10 spinal cord injury was conducted in rats.The model group was treated with intraperitoneal administration of riluzole with solvent cyclodextrin.The riluzole group was treated with a 4 mg/kg dose of riluzole injection.The effect of riluzole on motor function recovery was assessed using the BBB score and inclined plane test.The recovery of sensory-evoked potential and motor-evoked potential was measured by electrophysiology.Hematoxylin-eosin staining was used to evaluate spinal cord tissue repair.The regulatory effects of riluzole on NLRP3,Caspase-1 and gasdermin D protein expression in spinal cord tissues were detected by western blot assay.ELISA was utilized to detect the expression levels of inflammatory factors interleukin-1β and interleukin-18.The effects of riluzole on the expression of NLRP3,Caspase-1,gasdermin D and interleukin-1β in microglial cells of the injured spinal cord were determined by immunofluorescence staining. RESULTS AND CONCLUSION:(1)At 35 days after spinal cord injury,BBB score and inclined plane test score in the riluzole group were higher than those in the model group(P<0.05).(2)At 3 days after spinal cord injury,the protein expressions of NLRP3,cleaved Caspase-1,gasdermin D-N(N-terminal domain),interleukin-1β,and interleukin-18 in the spinal cord homogenate of the riluzole group were significantly lower than those of the model group(P<0.05).(3)At 3 days after spinal cord injury,the fluorescence intensity of NLRP3,Caspase-1,gasdermin D and interleukin-1β in the riluzole group was significantly lower than that in the model group(P<0.05).(4)At day 35 after spinal cord injury,hematoxylin-eosin staining showed that the area of spinal cord injury in the riluzole group was smaller than that in the model group.Electrophysiological tests showed that the latency periods of sensory-evoked potential and motor-evoked potential in the riluzole group were shorter than those in the model group,and the latency period of wave amplitude in the riluzole group was higher than that in the model group.(5)These results suggest that riluzole can promote the repair of injured spinal cord tissue,promote the repair of nerve conduction function,and further promote the recovery of motor function in rats with spinal cord injury,which may be achieved through the regulation of NLRP3 inflammasome and the reduction of microglial pyroptosis.

BACKGROUND:Neuroinflammation is an important factor leading to secondary spinal cord injury,and microglia/macrophage pyroptosis is a significant part of post-spinal cord injury neuroinflammation.Studies have shown that microglia/macrophage undergoes pyroptosis after spinal cord injury,but the regulatory mechanism of circular RNA(circRNA)in microglia/macrophage pyroptosis after spinal cord injury remains unclear. OBJECTIVE:To investigate the role and mechanism of circRNA0005512 in regulating microglia/macrophage pyroptosis after spinal cord injury. METHODS:Female Wistar rats were divided into sham group and spinal cord injury group.Motor function was evaluated using the Basso,Beattie,and Bresnahan(BBB)scale.Cavity volume was assessed by hematoxylin-eosin staining.Differential expression of circRNA in spinal cord tissue was screened using RNA-sequencing and circ0005512 was validated by real-time PCR.Immunofluorescence,western blot assay,ELISA,and real-time PCR were performed to detect cell pyroptosis in the rats and lipopolysaccharide-induced microglial cell line HAPI cell models.Gene knockdown was used to confirm the regulatory role of circRNA0005512 in microglia/macrophage pyroptosis. RESULTS AND CONCLUSION:(1)Seven days after spinal cord injury,evident cavities were observed at the injury site.Immediately after spinal cord injury,the motor function of rats was completely lost.Over time,the motor function of rats in the spinal cord injury group gradually partially recovered,and there was a significant difference in BBB scores compared to the sham group.(2)Circ0005512 was significantly upregulated according to the results of the RNA-sequencing and confirmed in both the animal and cell models.(3)Immunofluorescence,western blot assay,real-time PCR,and ELISA confirmed the significant upregulation of cell pyroptosis markers(NLRP3,GSDMD,and caspase-1)in spinal cord injury tissue and lipopolysaccharide-induced HAPI cells.(4)In the cell model,knockdown of circ0005512 resulted in significantly decreased levels of cell pyroptosis marker-NLRP3.(5)The results above indicate that circ0005512 promotes pyroptosis in microglia/macrophages after spinal cord injury.

OBJECTIVE: To investigate the clinical application of high-frequency color Doppler ultrasound (HFCDU) in detecting perforators in the deep adipose layers for harvesting super-thin anterolateral thigh flap (ALTF). METHODS: Between August 2019 and January 2023, 45 patients (46 sides) with skin and soft tissue defects in the foot and ankle were treated, including 29 males and 16 females, aged from 22 to 62 years, with an average of 46.7 years. The body mass index ranged from 19.6 to 36.2 kg/m ², with an average of 23.62 kg/m ². The causes of injury included traffic accident injury in 15 cases, heavy object crush injury in 20 cases, mechanical injury in 8 cases, heat crush injury in 1 case, and chronic infection in 1 case. There were 20 cases on the left side, 24 cases on the right side, and 1 case on both sides. After thorough debridement, the wound size ranged from 5 cm×4 cm to 17 cm×11 cm. All patients underwent free super-thin ALTF transplantation repair. HFCDU was used to detect the location of the perforators piercing the deep and superficial fascia, as well as the direction and branches of the perforators within the deep adipose layers before operation. According to the preoperative HFCDU findings, the dimensions of the super-thin ALTF ranged from 6 cm×4 cm to 18 cm×12 cm. The donor sites of the flaps were directly sutured. RESULTS: A total of 55 perforators were detected by HFCDU before operation, but 1 was not found during operation. During operation, a total of 56 perforators were found, and 2 perforators were not detected by HFCDU. The positive predictive value of HFCDU for identifying perforator vessels was 98.2%, and the sensitivity was 96.4%. Among the 54 perforators accurately located by HFCDU, the orientation of the perforators in the deep adipose layers was confirmed during operation. There were 21 perforators (38.9%) traveled laterally and inferiorly, 12 (22.2%) traveled medially and inferiorly, 14 (25.9%) traveled laterally and superiorly, 5 (9.3%) traveled medially and superiorly, and 2 (3.7%) ran almost vertically to the body surface. Among the 54 perforators accurately located by HFCDU, 35 were identified as type 1 perforators and 12 as type 2 perforators (HFCDU misidentified 7 type 2 perforators as type 1 perforators). The sensitivity of HFCDU in identifying type 1 perforators was 100%, with a positive predictive value of 83.3%. For type 2 perforators, the sensitivity was 63.2%, and the positive predictive value was 100%. The surgeries were successfully completed. The super-thin ALTF had a thickness ranging from 2 to 6 mm, with an average of 3.56 mm. All super-thin ALTF survived, however, 1 flap experienced a venous crisis at 1 day after operation, but it survived after emergency exploration and re-anastomosis of the veins; 1 flap developed venous crisis at 3 days after operation but survived after bleeding with several small incisions; 3 flaps had necrosis at the distal edge of the epidermis, which healed after undergoing dressing changes. All 45 patients were followed up 6-18 months (mean, 13.6 months). Three flaps required secondary defatting procedures, while the rest had the appropriate thickness, and the overall appearance was satisfactory. CONCLUSION Preoperative application of HFCDU to detect the perforator in the deep adipose layers can improve the success and safety of the procedure by facilitating the harvest of super-thin ALTF.
Male ; Female ; Humans ; Thigh/surgery* ; Plastic Surgery Procedures ; Prospective Studies ; Skin Transplantation ; Free Tissue Flaps ; Burns ; Soft Tissue Injuries/surgery* ; Ultrasonography, Doppler, Color ; Crush Injuries/surgery* ; Perforator Flap ; Treatment Outcome

ObjectiveTo evaluate the clinical efficacy of Chaigui Zengmian prescription （composed of Bupleuri Radix， Codonopsis Radix， Scutellariae Radix， Cinnamomi Ramulus， Paeoniae Radix Alba， Astragali Radix， Atractylodis Macrocephalae Rhizoma， and Scorpio） in treating recurrent respiratory tract infections in children with syndrome of Qi deficiency in lung and spleen and the influences of this prescription on immune factors. MethodSixty-six children suffering from recurrent respiratory tract infections due to Qi deficiency in lung and spleen were selected and randomized into a control group （33 cases） and an observation group （33 cases）. The control group received spleen aminopeptide oral lyophilized powder and the observation group was treated with self-made Chaigui Zengmian prescription granules. Both groups were treated for two months （as two consecutive courses of treatment）. The traditional Chinese medicine （TCM） symptom scores and the serum levels of total immunoglobulins （IgA， IgM， and IgG） and T-helper cells （Th1， Th2， and Th1/Th2） were measured in both groups before and after treatment and then compared. Result① After treatment， the TCM symptom scores of both groups declined and the observation group had lower scores than the control group （P<0.05）. ② The observation group［87.50%（28/32）］ had higher total response rate than the control group［96.88%（31/32）］（Z=7.921，P<0.05）.Also the observation group［28.13%（9/32）］ had more cured children than the control group［6.25（2/32）］ （χ²=5.379，P<0.05） ③ After treatment， the serum levels of IgA， IgM， IgG， Th1， and Th1/Th2 elevated while that of Th2 declined （P<0.05）， and the changes were more obvious in the observation group than in the control group （P<0.05）. ConclusionChaigui Zengmian prescription is effective in treating recurrent respiratory tract infections in children with the syndrome of Qi deficiency in lung and spleen. It can alleviate the symptoms and rectify immune disequilibrium， demonstrating a clinical application value.

Objective:To analyze plaque characteristics of non-culprit coronary lesions with cholesterol crystals in patients with acute myocardial infarction(AMI) by using optical coherence tomography(OCT). We also investigated the potential association between cholesterol crystals with plaque rupture and healed plaque at non-culprit segment.Methods:This study was a retrospective cohort study. Between January 2017 and December 2017, patients with AMI who underwent 3-vessel OCT imaging were included in this study. Patients were divided into two groups according to the presence or absence of cholesterol crystals at the non-culprit lesions. All patients underwent coronary angiography and OCT examination, and non-culprit plaque characteristics were compared between the two groups. The generalized estimating equation log-binomial multirariate regression model was used to assess the relationship between non-culprit lesions with cholesterol crystals and plaque rupture and plaque healing. The follow-up data collection ended in October 2023. Kaplan-Meier survival curves were plotted, and log-rank tests were used to compare the cumulative incidence of major adverse cardiovascular events between the two groups.Results:A total of 173 AMI patients were included (aged (56.8±11.6) years; 124 men (71.7%)). Among 710 non-culprit lesions identified by OCT, there were 102 (14.4%) in cholesterol crystals group and 608 (85.6%) in non-cholesterol crystals group. Compared with non-culprit lesions without cholesterol crystals, those with cholesterol crystals had smaller minimum lumen diameter, severer diameter stenosis, and longer lesion length (all P<0.01). The prevalence of plaque rupture (17.6% (18/102) vs. 4.9% (30/608), P=0.001) and thin-cap fibroatheroma (31.4% (32/102) vs. 11.5% (70/608), P<0.01) was higher in the cholesterol crystals groups than in the non-cholesterol crystals group. In addition, vulnerable plaque characteristics such as (44.1% (45/102) vs. 25.8% (157/608), P<0.01), macrophages were more frequently observed in non-culprit lesions with cholesterol crystals. The generalized estimating equation log-binomial multivariate regression analyses showed that non-culprit cholesterol crystals were positively correlated with healed plaque ( OR=1.583, 95% CI: 1.004-2.495, P=0.048). Conversely, cholesterol crystals were not associated with plaque rupture ( OR=1.632, 95% CI: 0.745-3.576, P=0.221). The follow-up time was 2 142 (1 880, 2 198) days. Non-culprit cholesterol crystals were not related to the major adverse cardiovascular events in patients with AMI (log-rank P=0.558). Conclusions:Among AMI patients, non-culprit lesions with cholesterol crystals presented with severer luminal stenosis and increased plaque vulnerability. The presence of non-culprit cholesterol crystals was associated with rather than plaque rupture.

Objective:To explore the differences in clinical and injured vertebra radiological parameters between patients with non-traumatic osteoporotic vertebral compression fracture (OVCF) and those with traumatic OVCF after percutaneous vertebroplasty (PVP).Methods:A retrospective study was conducted to analyze the 369 OVCF patients (with 458 vertebrae injured) who had been treated by PVP at Department of Orthopaedics, Beijing Luhe Hospital between October 2015 and March 2017. There were 292 females and 77 males with a mean age of 73 (60, 79) years. Based on the absence or presence of a trauma history, the patients were stratified into a non-traumatic group (127 patients with 160 vertebrae injured) and a traumatic group (242 patients with 298 vertebrae injured). Clinical parameters [age, gender, body mass index, symptomatic duration, and number of injured vertebrae, visual analogue scale (VAS), Oswestry disability index (ODI), duration of follow-up, and rate of new OVCFs] and injured vertebra radiological parameters (position of injured vertebra, fracture type, compression severity, fracture range, cortical defect, intravertebral cleft, spinal canal compromise, basivertebral foramen, morphology of bone cement, range of bone cement, cement leakage, cement volume, rate of vertebral height restoration, recollapse of cemented vertebrae) were recorded perioperatively. All the clinical and radiological parameters were compared between the 2 groups.Results:Compared with the traumatic group, the non-traumatic group had an older age [75 (71, 83) years versus 71 (65, 76) years], more females (85.0% versus 76.0%), a longer symptomatic duration [10.0 (7.0, 15.0) d versus 6.5 (2.0, 12.0) d], a lower preoperative VAS pain score [7 (6, 8) points versus 7 (7, 8) points], a lower VAS pain score at postoperative day 1 [2 (2, 3) points versus 2 (2, 3) points], a lower preoperative ODI [66% (63%, 72%) versus 70% (65%, 73 %)], a lower ODI at postoperative day 1 [32% (30%, 34%) versus 32% (31%, 34%)], a higher rate of new OVCFs during follow-up (34.6% versus 12.8%), a lower rate of thoracolumbar lesions (51.9% versus 70.1%), more deformed fractures (mostly amphicoelous type), a lower rate of cortical defects in the anterior wall (20.0% versus 31.5%), a higher rate of trabecular pattern of cement (83.1% versus 71.8%), a higher rate of type-B cement leakage (50.6% versus 31.9%), a lower rate of type-C cement leakage (5.6% versus 12.8%), a lower rate of recollapse of cemented vertebrae (43.8% versus 55.4%). All the comparisons above were statistically significant ( P<0.05). There were no significant differences between the 2 groups in the other clinical or radiological parameters ( P>0.05). Conclusions:There are statistically significant differences in a significant number of clinical and injured vertebra radiological parameters between patients with non-traumatic OVCF and those with traumatic OVCF after PVP. It is noteworthy that non-traumatic OVCFs are one specific subgroup of OVCFs.