Background Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen for both human bloodstream infections and mastitis in cows. However, little attention has been paid to the cross-host transmission of MRSA from cows to high-risk groups in China. Objective To determine the MRSA colonization rates among dairy cows and dairy farm workers in Xinjiang, identify the antibiotic resistance profiles and molecular characteristics of the isolates, and provide scientific evidence for the formulation of targeted infection control strategies. Method A cross-sectional survey combined with laboratory pathogen analysis was conducted. From June to August 2024, large-scale dairy farms in Xinjiang region were selected as study sites. Nasal swabs (n=96) and skin swabs (n=39) were collected from workers, and bovine nasal swab samples (n=109) were collected simultaneously. All samples were subjected to MRSA isolation, cultivation, and identification, followed by antibiotic susceptibility testing to characterize resistance phenotypes. Staphylococcus aureus protein A (Spa) typing was performed to determine strain genotypes and elucidate MRSA colonization rates and molecular epidemiological patterns. Results A total of 35 MRSA strains was successfully isolated from 244 samples. The MRSA colonization rates among dairy farm workers and dairy cows were 20.83% (20/96) and 12.84% (14/109), respectively, with an overall isolation rate of 14.34% (35/244). Among the workers, the nasal colonization rate was 16.67% (16/96), and the skin colonization rate was 12.82% (5/39). One worker exhibited MRSA colonization at multiple body sites. All MRSA strains were resistant to cefoxitin (100%, 35/35). The resistance rates to erythromycin and clindamycin were 42.86% (15/35) and 34.29% (12/35), respectively. Thirteen strains showed a multidrug-resistant phenotype, whereas all strains were susceptible to vancomycin. The MRSA isolates exhibited high genetic diversity, with 13 Spa types identified, among which t441 was the most prevalent (8 strains). Both t441 and t034 types were detected in samples from both the dairy cows and their handlers. These two Spa types also carried and stably inherited specific resistance combinations, including erythromycin–clindamycin–cefoxitin and ciprofloxacin–erythromycin–clindamycin–gentamicin–cefoxitin–tetracycline, and a statistically significant association was also observed between the two resistance profiles and the bacterial types (P < 0.001). In addition, one novel Spa type strain was identified. Conclusion MRSA colonization rates among dairy cows and dairy farm workers in Xinjiang are relatively high, with evidence of multi-site colonization. The isolates exhibit high levels of multidrug resistance and genetic diversity, indicating a potential risk of cross-host transmission.

ObjectiveTo clarify whether METTL14 mediates the core role of acupuncture at Neiguan (PC6) in promoting myelination and improving behavior in young autistic rats through gene intervention technology. MethodsThe ASD model was established by intraperitoneal injection of valproic acid (VPA) in pregnant rats. Male offspring were intracerebroventricularly injected with adenovirus-packaged METTL14 shRNA (sh-METTL14) or its control (sh-NC) on postnatal day 1, with a model group set as well. Subsequently, the juvenile rats were divided into model group, acupuncture group, acupuncture+sh-NC group, and acupuncture+sh-METTL14 group. The acupuncture group received acupuncture at Neiguan (PC6) from postnatal day 7, once daily for 21 consecutive days. Neurobehavioral changes were evaluated by behavioral tests; METTL14 knockdown efficiency and the expression of METTL14, METTL3, and PTEN were detected by quantitative real-time PCR (qRT-PCR) and Western blot (WB); PTEN m⁶A levels were measured by RNA immunoprecipitation-qPCR (RIP-qPCR); myelin ultrastructure, expression of myelin basic protein (MBP) and neurofascin 155 (NF155), and dendritic spine density were observed using transmission electron microscopy (TEM), enzyme-linked immunosorbent assay (ELISA), immunofluorescence, qRT-PCR, and primary neuron culture. ResultsBehaviorally, knockdown of METTL14 significantly counteracted the beneficial effects of acupuncture in improving self-grooming, open field exploration, three-chamber social interaction, and Morris water maze learning and memory (P<0.05, P<0.01). Compared with the acupuncture+sh-NC group, the acupuncture+sh-METTL14 group showed significantly decreased mRNA and protein expression of hippocampal METTL14 (P<0.01), and the upregulating effects of acupuncture on METTL3 and PTEN expression were reversed (P<0.01). Meanwhile, knockdown of METTL14 significantly inhibited the acupuncture-induced increase in PTEN m⁶A levels (P<0.01). Morphologically, knockdown of METTL14 attenuated the improvement of myelin structure by acupuncture, reversed the downregulation of MBP and upregulation of NF155 induced by acupuncture, and blocked the increase in dendritic spine density (P<0.05, P<0.01). ConclusionMETTL14 is a key molecule mediating the therapeutic effect of acupuncture at Neiguan. Acupuncture at Neiguan upregulates METTL14, thereby enhancing m⁶A methylation modification of PTEN mRNA to stabilize its expression, ultimately promoting myelin development and improving behavioral symptoms in ASD juvenile rats. This preliminarily reveals the modern biological connotation of “opening Xuanfu and dredging myelin”.

ObjectiveTo clarify whether METTL14 mediates the core role of acupuncture at Neiguan (PC6) in promoting myelination and improving behavior in young autistic rats through gene intervention technology. MethodsThe ASD model was established by intraperitoneal injection of valproic acid (VPA) in pregnant rats. Male offspring were intracerebroventricularly injected with adenovirus-packaged METTL14 shRNA (sh-METTL14) or its control (sh-NC) on postnatal day 1, with a model group set as well. Subsequently, the juvenile rats were divided into model group, acupuncture group, acupuncture+sh-NC group, and acupuncture+sh-METTL14 group. The acupuncture group received acupuncture at Neiguan (PC6) from postnatal day 7, once daily for 21 consecutive days. Neurobehavioral changes were evaluated by behavioral tests; METTL14 knockdown efficiency and the expression of METTL14, METTL3, and PTEN were detected by quantitative real-time PCR (qRT-PCR) and Western blot (WB); PTEN m⁶A levels were measured by RNA immunoprecipitation-qPCR (RIP-qPCR); myelin ultrastructure, expression of myelin basic protein (MBP) and neurofascin 155 (NF155), and dendritic spine density were observed using transmission electron microscopy (TEM), enzyme-linked immunosorbent assay (ELISA), immunofluorescence, qRT-PCR, and primary neuron culture. ResultsBehaviorally, knockdown of METTL14 significantly counteracted the beneficial effects of acupuncture in improving self-grooming, open field exploration, three-chamber social interaction, and Morris water maze learning and memory (P<0.05, P<0.01). Compared with the acupuncture+sh-NC group, the acupuncture+sh-METTL14 group showed significantly decreased mRNA and protein expression of hippocampal METTL14 (P<0.01), and the upregulating effects of acupuncture on METTL3 and PTEN expression were reversed (P<0.01). Meanwhile, knockdown of METTL14 significantly inhibited the acupuncture-induced increase in PTEN m⁶A levels (P<0.01). Morphologically, knockdown of METTL14 attenuated the improvement of myelin structure by acupuncture, reversed the downregulation of MBP and upregulation of NF155 induced by acupuncture, and blocked the increase in dendritic spine density (P<0.05, P<0.01). ConclusionMETTL14 is a key molecule mediating the therapeutic effect of acupuncture at Neiguan. Acupuncture at Neiguan upregulates METTL14, thereby enhancing m⁶A methylation modification of PTEN mRNA to stabilize its expression, ultimately promoting myelin development and improving behavioral symptoms in ASD juvenile rats. This preliminarily reveals the modern biological connotation of “opening Xuanfu and dredging myelin”.

ObjectiveTo explore the effect of modified Lianpoyin formula （LPYJWF） in the treatment of Helicobacter pylori （Hp）-associated gastric mucosal damage based on mitochondrial autophagy and NLRP3 inflammasome signaling pathway. MethodsA total of 60 eight-week-old Balb/c male mice were assigned via the random number table method into control， model， high-dose LPYJWF （LPYJWF-H， 27.3 g·kg^-1·d^-1）， medium-dose LPYJWF （LPYJWF-M， 13.65 g·kg^-1·d^-1）， low-dose LPYJWF （LPYJWF-L， 6.83 g·kg^-1·d^-1）， and quadruple therapy groups. Except the control group， other groups were modeled for Hp infection. Mice were administrated with LPYJWF at corresponding doses by gavage. Quadruple therapy group was given omeprazole （6.06 mg·kg^-1·d^-1） + amoxicillin （303 mg·kg^-1·d^-1） + clarithromycin （151.67 mg·kg^-1·d^-1） + colloidal pectin capsules （30.3 mg·kg^-1·d^-1） by gavage. The control group was given an equal volume of 0.9% NaCl for 14 days. Hematoxylin-eosin （HE） staining was used to observe the pathological changes of gastric mucosa， and Warthin-Starry （W-S） silver staining was used to detect Hp colonization. Transmission electron microscopy was employed to observe the mitochondrial ultrastructure of the gastric tissue， and immunofluorescence co-localization assay was adopted to detect the expression of mitochondrial transcription factor A （TFAM） and translocase of the outer mitochondrial membrane member 20 （TOMM20）. The water-soluble tetrazolium salt method and thiobarbituric acid method were used to determine the levels of superoxide dismutase （SOD） and malondialdehyde （MDA）， respectively， in the gastric tissue. Western blot was employed to measure the protein levels of PTEN-induced kinase 1 （PINK1）， Parkin， p62， microtubule-associated protein 1 light chain 3 （LC3）， NOD-like receptor protein 3 （NLRP3）， apoptosis-associated speck-like protein containing a CARD （ASC）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18）. Real-time quantitative PCR was employed to assess the mRNA levels of PINK1， Parkin， p62， and LC3. ResultsCompared with the control group， the model group presented obvious gastric mucosal damage， colonization of a large number of Hp， severe mitochondrial damage， vacuolated structures due to excessive autophagy， reduced TOMM20 and TFAM co-expression in the gastric mucosal tissue， and reduced SOD and increased MDA （P<0.01）. In addition， the gastric tissue in the model group showed up-regulated protein and mRNA levels of PINK1， Parkin， and LC3 and down-regulated protein and mRNA levels of p62 （P<0.01， as well as increased expression of inflammasome-associated proteins NLRP3， ASC， IL-1β， and IL-18 （P<0.01）. Compared with the model group， the LPYJWF and quadruple therapy groups showed alleviated pathological damage of gastric mucosa， reduced Hp colonization， mitigated mitochondrial damage， and increased co-expression of TOMM20 and TFAM. The SOD level was elevated in the LPYJWF-L group （P<0.01）， and the MDA levels became lowered in the LPYJWF and quadruple therapy groups （P<0.05， P<0.01）. Furthermore， the LPYJWF and quadruple therapy groups showed down-regulated mRNA levels of PINK1， Parkin， and LC3 and protein levels of PINK1 and Parkin， and up-regulated mRNA level of p62 （P<0.01）. The LPYJWF-M， LPYJWF-H， and quadruple therapy groups showcased down-regulated LC3 Ⅱ/LC3 Ⅰ level （P<0.05， P<0.01） and up-regulated protein level of p62 （P<0.01）. The expression of inflammasome-associated proteins NLRP3， ASC， IL-1β， and IL-18 were reduced in the LPYJWF and quadruple therapy groups （P<0.05， P<0.01）. ConclusionLPYJWF ameliorates gastric mucosal damage and exerts mucosa-protective effects in Hp-infected mice， which may be related to the inhibition of excessive mitochondrial autophagy， thereby inhibiting the activation of the NLRP3 inflammasome pathway.

ObjectiveTo explore the effect of modified Lianpoyin formula （LPYJWF） in the treatment of Helicobacter pylori （Hp）-associated gastric mucosal damage based on mitochondrial autophagy and NLRP3 inflammasome signaling pathway. MethodsA total of 60 eight-week-old Balb/c male mice were assigned via the random number table method into control， model， high-dose LPYJWF （LPYJWF-H， 27.3 g·kg^-1·d^-1）， medium-dose LPYJWF （LPYJWF-M， 13.65 g·kg^-1·d^-1）， low-dose LPYJWF （LPYJWF-L， 6.83 g·kg^-1·d^-1）， and quadruple therapy groups. Except the control group， other groups were modeled for Hp infection. Mice were administrated with LPYJWF at corresponding doses by gavage. Quadruple therapy group was given omeprazole （6.06 mg·kg^-1·d^-1） + amoxicillin （303 mg·kg^-1·d^-1） + clarithromycin （151.67 mg·kg^-1·d^-1） + colloidal pectin capsules （30.3 mg·kg^-1·d^-1） by gavage. The control group was given an equal volume of 0.9% NaCl for 14 days. Hematoxylin-eosin （HE） staining was used to observe the pathological changes of gastric mucosa， and Warthin-Starry （W-S） silver staining was used to detect Hp colonization. Transmission electron microscopy was employed to observe the mitochondrial ultrastructure of the gastric tissue， and immunofluorescence co-localization assay was adopted to detect the expression of mitochondrial transcription factor A （TFAM） and translocase of the outer mitochondrial membrane member 20 （TOMM20）. The water-soluble tetrazolium salt method and thiobarbituric acid method were used to determine the levels of superoxide dismutase （SOD） and malondialdehyde （MDA）， respectively， in the gastric tissue. Western blot was employed to measure the protein levels of PTEN-induced kinase 1 （PINK1）， Parkin， p62， microtubule-associated protein 1 light chain 3 （LC3）， NOD-like receptor protein 3 （NLRP3）， apoptosis-associated speck-like protein containing a CARD （ASC）， interleukin-1β （IL-1β）， and interleukin-18 （IL-18）. Real-time quantitative PCR was employed to assess the mRNA levels of PINK1， Parkin， p62， and LC3. ResultsCompared with the control group， the model group presented obvious gastric mucosal damage， colonization of a large number of Hp， severe mitochondrial damage， vacuolated structures due to excessive autophagy， reduced TOMM20 and TFAM co-expression in the gastric mucosal tissue， and reduced SOD and increased MDA （P<0.01）. In addition， the gastric tissue in the model group showed up-regulated protein and mRNA levels of PINK1， Parkin， and LC3 and down-regulated protein and mRNA levels of p62 （P<0.01， as well as increased expression of inflammasome-associated proteins NLRP3， ASC， IL-1β， and IL-18 （P<0.01）. Compared with the model group， the LPYJWF and quadruple therapy groups showed alleviated pathological damage of gastric mucosa， reduced Hp colonization， mitigated mitochondrial damage， and increased co-expression of TOMM20 and TFAM. The SOD level was elevated in the LPYJWF-L group （P<0.01）， and the MDA levels became lowered in the LPYJWF and quadruple therapy groups （P<0.05， P<0.01）. Furthermore， the LPYJWF and quadruple therapy groups showed down-regulated mRNA levels of PINK1， Parkin， and LC3 and protein levels of PINK1 and Parkin， and up-regulated mRNA level of p62 （P<0.01）. The LPYJWF-M， LPYJWF-H， and quadruple therapy groups showcased down-regulated LC3 Ⅱ/LC3 Ⅰ level （P<0.05， P<0.01） and up-regulated protein level of p62 （P<0.01）. The expression of inflammasome-associated proteins NLRP3， ASC， IL-1β， and IL-18 were reduced in the LPYJWF and quadruple therapy groups （P<0.05， P<0.01）. ConclusionLPYJWF ameliorates gastric mucosal damage and exerts mucosa-protective effects in Hp-infected mice， which may be related to the inhibition of excessive mitochondrial autophagy， thereby inhibiting the activation of the NLRP3 inflammasome pathway.

Trauma is an important cause of death in young- and middle-aged people. Trauma is comprehensive and includes many surgical specialties, and the surgical techniques of these specialties have long been mature. To reduce the mortality and disability rate of trauma patients, it is necessary to improve trauma management. Trauma has attracted attention in China and trauma treatment and care developed rapidly in recent years. To decrease traumatic mortality and disability rates, our team is committed to building an efficient trauma system in Shaanxi province and has successfully developed a trauma limb salvage map to address the high rates of amputation and disability in patients with limb injuries. This article elaborates on the construction experience of a trauma limb salvage map and its application details in Shaanxi province of China.
Humans ; China ; Limb Salvage/methods* ; Wounds and Injuries/surgery* ; Male ; Extremities/injuries* ; Adult ; Amputation, Surgical ; Middle Aged ; Female

Parameters of peripheral blood cell have been shown as the potential predictors of erectile dysfunction (ED). To investigate the clinical significance of hematological parameters for predicting the risk of rapid ejaculation, we established a rat copulatory model on the basis of ejaculation distribution theory. Blood samples from different ejaculatory groups were collected for peripheral blood cell counts and serum serotonin (5-HT) tests. Meanwhile, the relationship between hematological parameters and ejaculatory behaviors was assessed. Final analysis included 11 rapid ejaculators, 10 normal ejaculators, and 10 sluggish ejaculators whose complete data were available. The platelet (PLT) count in rapid ejaculators was significantly lower than that in normal and sluggish ejaculators, whereas the platelet distribution width (PDW) and mean platelet volume (MPV) were significantly greater in rapid ejaculators. Multivariate logistic regression analysis and receiver operating characteristic (ROC) curve analysis showed that the PLT was an independent protective factor for rapid ejaculation. Meanwhile, rapid ejaculators were found to have the lowest serum 5-HT compared to normal and sluggish ejaculators ( P < 0.001). Furthermore, there was a positive correlation between the PLT and serum 5-HT ( r = 0.662, P < 0.001), indicating that the PLT could indirectly reflect the serum 5-HT concentration. In addition, we assessed the association between the PLT and ejaculatory parameters. There was a negative correlation between ejaculation frequency (EF) and the PLT ( r = -0.595, P < 0.001), whereas there was a positive correlation between ejaculation latency (EL) and the PLT ( r = 0.740, P < 0.001). This study indicated that the PLT might be a useful and convenient diagnostic marker for predicting the risk of rapid ejaculation.
Male ; Animals ; Ejaculation/physiology* ; Rats ; Platelet Count ; Pilot Projects ; Serotonin/blood* ; Biomarkers/blood* ; Mean Platelet Volume ; Rats, Sprague-Dawley ; ROC Curve ; Erectile Dysfunction/physiopathology*

OBJECTIVES: To explore the mediating role of sleep duration in the relationship between depression symptoms and myopia among middle school students. METHODS: This study was a cross-sectional research conducted using a stratified cluster random sampling method. A total of 1 728 middle school students were selected from two junior high schools and two senior high schools in certain urban areas and farms of the Xinjiang Production and Construction Corps. Questionnaire surveys and vision tests were conducted among the students. Spearman analysis was used to analyze the correlation between depression symptoms, sleep duration, and myopia. The Bootstrap method was employed to investigate the mediating effect of sleep duration between depression symptoms and myopia. RESULTS: The prevalence of myopia in the overall population was 74.02% (1 279/1 728), with an average sleep duration of (7.6±1.0) hours. The rate of insufficient sleep was 83.62% (1 445/1 728), and the proportion of students exhibiting depression symptoms was 25.29% (437/1 728). Correlation analysis showed significant negative correlations between visual acuity in both eyes and sleep duration with depressive emotions as measured by the Center for Epidemiologic Studies Depression Scale (with correlation coefficients of -0.064, -0.084, and -0.199 respectively; P<0.01), as well as with somatic symptoms and activities (with correlation coefficients of -0.104, -0.124, and -0.233 respectively; P<0.01) and interpersonal relationships (with correlation coefficients of -0.052, -0.059, and -0.071 respectively; P<0.05). The correlation coefficients for left and right eye visual acuity and sleep duration were 0.206 and 0.211 respectively (P<0.001). Sleep duration exhibited a mediating effect between depression symptoms and myopia (indirect effect=0.056, 95%CI: 0.029-0.088), with the mediating effect value for females (indirect effect=0.066, 95%CI: 0.024-0.119) being higher than that for males (indirect effect=0.042, 95%CI: 0.011-0.081). CONCLUSIONS Sleep duration serves as a partial mediator between depression symptoms and myopia in middle school students.
Humans ; Myopia/etiology* ; Male ; Female ; Depression/physiopathology* ; Cross-Sectional Studies ; Sleep ; Adolescent ; Students ; Child ; Time Factors ; Sleep Duration

Objective:To investigate the significance of urinary 8-oxo-7, 8-dihydroguanosine(8-oxoGuo)in assessing the short-term prognosis of sepsis in frail elderly patients.Methods:We conducted a cross-sectional study involving 62 frail elderly patients diagnosed with sepsis who were admitted to the Emergency Intensive Care Unit(EICU)at Beijing Hospital between March 2021 and March 2022.Based on their 28-day prognosis, the patients were categorized into two groups: those who died and those who survived.Upon admission, we collected urine samples and clinical data from both groups.We employed isotope dilution high-performance liquid chromatography-mass spectrometry to measure the levels of the RNA oxidation marker 8-oxoGuo in the urine.Results:A total of 62 frail elderly patients[aged(85.1±6.3)years]diagnosed with sepsis were included in the study, comprising 36 patients in the 28-day mortality group and 26 patients in the survival group.Univariate analysis revealed that the survival group had significantly lower body temperature, blood calcitonin(PCT)levels, sequential organ failure assessment(SOFA)scores, and urinary 8-oxoGuo levels compared to the mortality group.Additionally, the survival group exhibited a higher mean arterial pressure(MAP)than the mortality group, with all differences reaching statistical significance(all P<0.05).Spearman correlation analysis indicated that urinary 8-oxoGuo levels were positively correlated with both PCT and SOFA scores in frail elderly sepsis patients( r=0.426, 0.768, both P<0.05).Furthermore, logistic regression analysis identified urinary 8-oxoGuo and SOFA as independent risk factors for 28-day mortality in this population( OR=1.936, 1.427; P=0.006, 0.002).The area under the receiver operating characteristic curve(AUC)for urinary 8-oxoGuo and SOFA in predicting the 28-day prognosis of frail elderly sepsis patients was 0.761 and 0.741, respectively, both demonstrating statistical significance(both P<0.001). Conclusions:Our findings suggest that urinary 8-oxoGuo possesses strong predictive value for the short-term prognosis of sepsis in this vulnerable population.

ObjectiveMicrotube associated protein-2 （MAP-2）， alpha-tubulin （α-tubulin）， and synaptophysin （SYP） are important proteins in neuronal signal communication. This paper observed the effects of modified Zhigancao Tang on the expression of serum α-Synuclein （α-Syn） and its oligomers， MAP-2， α-tubulin， and SYP of patients with liver and kidney deficiency of Parkinson's disease （PD）， analyzed their correlation， and evaluated the therapeutic effect of modified Zhigancao Tang in patients with liver and kidney deficiency of PD based on α-Syn transmission pathway mediated by neuronal communication in vivo. MethodsA total of 60 patients with PD who met the inclusion criteria were randomly divided into a treatment group （30 cases） and a control group （30 cases）. Both groups were treated on the basis of PD medicine， and the treatment group was treated with modified Zhigancao Tang. Both groups were treated for 12 weeks. The changes in UPDRS score， TCM syndrome score， and expression of serum α-Syn and its oligomers， MAP-2， α-tubulin， and SYP were observed before and after 12 weeks of treatment in each group. The correlation between the above-mentioned serum biological indexes and the levels of serum α-Syn and its oligomers was analyzed. ResultsAfter treatment， the TCM syndrome score， UPDRS score， UPDRS-Ⅱ score， and UPDRS-Ⅲ score of the treatment group were significantly decreased （P<0.05， P<0.01）. The UPDRS score， UPDRS-Ⅱ score， and UPDRS-Ⅲ scores in the treatment group were significantly decreased compared with those in the control group after treatment （P<0.05）. After treatment， the total effective rate of the control group was 63.3% （19/30）， and that of the treatment group was 86.7% （26/30）. The clinical effect of the observation group was better than the control group （Z=-2.03， P<0.05）. The total effective rate of the observation group was better than that of the control group， and the difference was statistically significant （χ²=5.136， P<0.05）. After treatment， the oligomer level of serum α-Syn and MAP-2 level in the treatment group were significantly decreased （P<0.05， P<0.01）. The levels of serum α-Syn and its oligomers， as well as α-tubulin in the treatment group， were significantly decreased compared with those in the control group after treatment （P<0.05， P<0.01）. Serum α-Syn was correlated with serum MAP-2 and α-Syn oligomer in patients with PD （P<0.05， P<0.01） but not correlated with serum SYP . Serum α-Syn oligomers of patients with PD were correlated with serum MAP-2 and α-tubulin （P<0.05， P<0.01） but not correlated with serum SYP level. Serum SYP of patients with PD was correlated with serum MAP-2 （P<0.05）. ConclusionModified Zhigancao Tang has a therapeutic effect on patients with liver and kidney deficiency of PD by inhibiting the production of α-Syn oligomers and intervening α-Syn microtubule transport pathway in vivo.