N⁶-methyladenosine (m⁶A) modification plays a critical role in cell cycle regulation, while the mechanism of m⁶A in regulating mitosis remains underexplored. Here, we found that the total m⁶A modification level in cells increased during mitosis by the liquid chromatography-mass spectrometry/mass spectrometry and m⁶A dot blot assays. Silencing methyltransferase-like 3 (METTL3) or METTL14 results in delayed mitosis, abnormal spindle assembly, and chromosome segregation defects by the immunofluorescence. By analyzing transcriptome-wide m⁶A targets in HeLa cells, we identified polo-like kinase 1 (PLK1) as a key gene modified by m⁶A in regulating mitosis. Specifically, through immunoblotting and RNA pulldown, m⁶A modification inhibits PLK1 translation via YTH N⁶-methyladenosine RNA binding protein 1, thus mediating cell cycle homeostasis. Demethylation of PLK1 mRNA leads to significant mitotic abnormalities. These findings highlight the critical role of m⁶A in regulating mitosis and the potential of m⁶A as a therapeutic target in proliferative diseases such as cancer.
Humans ; Polo-Like Kinase 1 ; Cell Cycle Proteins/metabolism* ; Proto-Oncogene Proteins/metabolism* ; Protein Serine-Threonine Kinases/metabolism* ; Mitosis/physiology* ; HeLa Cells ; Adenosine/genetics* ; Methyltransferases/metabolism* ; RNA, Messenger/metabolism* ; RNA-Binding Proteins/metabolism*

Objective To compare the effects of non-invasive intermittent oxygen-driven nebulization,non-invasive intermittent air-driven nebulization,and non-invasive simultaneous air-driven nebulization on the dynamic changes of partial pressure of carbon dioxide(PtCO2),pulse oxygen saturation(SpO2),and heart rate during nebulization,as well as the therapeutic effects in patients with acute exacerbation of chronic obstructive pulmonary disease(COPD).Methods A total of 99 patients with acute exacerbation of COPD requiring non-invasive mechanical ventilation and nebulization were randomly divided into a control group,an experimental group one,and an experimental group two,with 33 patients in each group.The control group was given non-invasive intermittent oxygen-driven nebulization,the experimental group one was given non-invasive intermittent air-driven nebulization,and the experimental group two was given non-invasive simultaneous air-driven nebulization.The changes in PtCO2,SpO2,and heart rate at 0 min,5 min,10 min,15 min during nebulization,5 min,10 min,and 15 min after nebulization were recorded.The values of arterial blood gas PaCO2 and PaO2 were recorded every morning from before treatment to the 7th day of treatment.The length of hospital stay in the three groups was also recorded.Results The comparison of PtCO2 during nebulization among the three groups showed that there were statistically significant differences in the main effect of time and the interaction effect of time and group(P<0.001).The PtCO2 values in the control group showed a linear relationship with time(F=10.166,P=0.003),increasing over time;the PtCO2 values in the experimental group one showed a linear relationship with time(F=10.544,P=0.003),decreasing over time;the PtCO2 values in the experimental group two showed a linear rela-tionship with time(F=20.003,P<0.001),decreasing over time.A one-way ANOVA was conducted on the PtCO2 values at each time point in the three groups.The PtCO2 value at 15 min of nebulization in the control group was higher than that in the experimental group one and the experimental group two.There were statistically signifi-cant differences in the difference in PtCO2 before and after nebulization(dPtCO2)between the experimental group one and the experimental group two and the control group(P<0.05).A one-way ANOVA was conducted on the PtCO2 values at each time point during the observation period after nebulization.The results showed that there were statistically significant differences in PtCO2 at 0 min and 5 min after nebulization among the three groups(P<0.05),while there were no statistically significant differences in PtCO2 at 10 min and 15 min after nebulization among the three groups(P>0.05).The comparison of SPO2 during nebulization among the three groups showed that there were statistically significant differences in the interaction effect of time and group(P<0.05).The SPO2 values in the experimental group one decreased over time.The SPO2 values at 10 min and 15 min of nebulization in the control group were higher than those in the experimental group one and the experimental group two.All three groups could improve PaCO2 in arterial blood gas with the treatment days(P<0.05).Conclusions All three nebu-lization treatment methods can achieve good therapeutic effects.However,non-invasive intermittent oxygen-driven nebulization can increase PtCO2 and SPO2 during nebulization;non-invasive intermittent air-driven nebulization can decrease PtCO2 and SPO2 during nebulization;non-invasive simultaneous air-driven nebulization can decrease PtCO2 and maintain stable SPO2 during nebulization.Therefore,non-invasive simultaneous air-driven nebulization is a relatively safer nebulization inhalation method and is worthy of clinical promotion.

Objective:To explore the effect of carboxylated polyamidoamine (PAMAM-COOH) in combination with magnesium ions on the remineralization ability of amorphous calcium phosphate (ACP) in inducing remineralization of dentin collagen fibers in a 50% ethanol solution.Methods:Forty-five intact third molars extracted for impaction reasons were obtained from the College & Hospital of Stomatology, Guangxi Medical University. Two types of demineralized dentin specimens were prepared: ①Fully demineralized dentin ( n=30), specimens were immersed in 17% ethylenediaminetetraacetic acid (EDTA) (pH=7.4) at room temperature for 14 days with daily solution refreshment; ②Partially demineralized dentin ( n=15), specimens were treated with 37% phosphoric acid gel (Ultra-Etch, Ultradent) for 15 seconds followed by thorough rinsing with deionized water. Three remineralization groups were established for demineralized dentin treatment: ①Control group, 50% ethanol solution; ②ACMP group, 50% ethanol solution containing amorphous magnesium calcium phosphate (ACMP); ③PAMAM-COOH/ACMP group, 50% ethanol solution incorporating carboxylated polyamidoamine dendrimer-modified ACMP (PAMAM-COOH/ACMP). The chemical composition of remineralization solutions was analyzed by Fourier-transform infrared spectrum (FTIR). The morphology and particle size distribution of nanoparticles were characterized using transmission electron microscope (TEM). The fully demineralized dentin specimens were treated with three different remineralization solutions (37 ℃ for 7 days) respectively. The mineralization of the dentin collagen fibers surface was observed using scanning electron microscope (SEM) and the distribution of minerals inside and outside the collagen fibers was examined by using TEM. The partially demineralized dentin specimens were treated with fluorescence-labeled remineralization solutions (37 ℃ for 7 days) respectively, followed by analysis using confocal laser scanning microscopy (CLSM) to quantitatively evaluate the penetration depth of the mineralization agents. Results:FTIR analysis confirmed the presence of characteristic absorption peaks corresponding to phosphate (PO 43-) groups, carbon-nitrogen bonds, and amide linkages in the PAMAM-COOH/ACMP nanocomposite. TEM observed that the PAMAM-COOH/ACMP nanoparticles exhibited an average particle size of (36.85±8.02) nm in an amorphous state. SEM observation indicates continuous mineral deposition on dentin collagen fibers in the PAMAM-COOH/ACMP group, while no mineral deposition in the control group and only minimal deposition in the ACMP group. TEM showed no mineral deposition inside or outside the collagen fibers in the control group, only external mineral deposition in the ACMP group, and high-density mineral deposition both inside and outside the fibers in the PAMAM-COOH/ACMP group. CLSM analysis revealed a statistically significant difference ( P<0.05) in the depth of mineralized substances entering dentin tubules between ACMP group and PAMAM-COOH/ACMP group. Conclusions:The remineralization system of 50% ethanol solution incorporating PAMAM-COOH/ACMP successfully achieved the internal and external mineralization of demineralized dentin collagen fibers.

Objective:To explore the effect of carboxylated polyamidoamine (PAMAM-COOH) in combination with magnesium ions on the remineralization ability of amorphous calcium phosphate (ACP) in inducing remineralization of dentin collagen fibers in a 50% ethanol solution.Methods:Forty-five intact third molars extracted for impaction reasons were obtained from the College & Hospital of Stomatology, Guangxi Medical University. Two types of demineralized dentin specimens were prepared: ①Fully demineralized dentin ( n=30), specimens were immersed in 17% ethylenediaminetetraacetic acid (EDTA) (pH=7.4) at room temperature for 14 days with daily solution refreshment; ②Partially demineralized dentin ( n=15), specimens were treated with 37% phosphoric acid gel (Ultra-Etch, Ultradent) for 15 seconds followed by thorough rinsing with deionized water. Three remineralization groups were established for demineralized dentin treatment: ①Control group, 50% ethanol solution; ②ACMP group, 50% ethanol solution containing amorphous magnesium calcium phosphate (ACMP); ③PAMAM-COOH/ACMP group, 50% ethanol solution incorporating carboxylated polyamidoamine dendrimer-modified ACMP (PAMAM-COOH/ACMP). The chemical composition of remineralization solutions was analyzed by Fourier-transform infrared spectrum (FTIR). The morphology and particle size distribution of nanoparticles were characterized using transmission electron microscope (TEM). The fully demineralized dentin specimens were treated with three different remineralization solutions (37 ℃ for 7 days) respectively. The mineralization of the dentin collagen fibers surface was observed using scanning electron microscope (SEM) and the distribution of minerals inside and outside the collagen fibers was examined by using TEM. The partially demineralized dentin specimens were treated with fluorescence-labeled remineralization solutions (37 ℃ for 7 days) respectively, followed by analysis using confocal laser scanning microscopy (CLSM) to quantitatively evaluate the penetration depth of the mineralization agents. Results:FTIR analysis confirmed the presence of characteristic absorption peaks corresponding to phosphate (PO 43-) groups, carbon-nitrogen bonds, and amide linkages in the PAMAM-COOH/ACMP nanocomposite. TEM observed that the PAMAM-COOH/ACMP nanoparticles exhibited an average particle size of (36.85±8.02) nm in an amorphous state. SEM observation indicates continuous mineral deposition on dentin collagen fibers in the PAMAM-COOH/ACMP group, while no mineral deposition in the control group and only minimal deposition in the ACMP group. TEM showed no mineral deposition inside or outside the collagen fibers in the control group, only external mineral deposition in the ACMP group, and high-density mineral deposition both inside and outside the fibers in the PAMAM-COOH/ACMP group. CLSM analysis revealed a statistically significant difference ( P<0.05) in the depth of mineralized substances entering dentin tubules between ACMP group and PAMAM-COOH/ACMP group. Conclusions:The remineralization system of 50% ethanol solution incorporating PAMAM-COOH/ACMP successfully achieved the internal and external mineralization of demineralized dentin collagen fibers.

Objective To compare the effects of non-invasive intermittent oxygen-driven nebulization,non-invasive intermittent air-driven nebulization,and non-invasive simultaneous air-driven nebulization on the dynamic changes of partial pressure of carbon dioxide(PtCO2),pulse oxygen saturation(SpO2),and heart rate during nebulization,as well as the therapeutic effects in patients with acute exacerbation of chronic obstructive pulmonary disease(COPD).Methods A total of 99 patients with acute exacerbation of COPD requiring non-invasive mechanical ventilation and nebulization were randomly divided into a control group,an experimental group one,and an experimental group two,with 33 patients in each group.The control group was given non-invasive intermittent oxygen-driven nebulization,the experimental group one was given non-invasive intermittent air-driven nebulization,and the experimental group two was given non-invasive simultaneous air-driven nebulization.The changes in PtCO2,SpO2,and heart rate at 0 min,5 min,10 min,15 min during nebulization,5 min,10 min,and 15 min after nebulization were recorded.The values of arterial blood gas PaCO2 and PaO2 were recorded every morning from before treatment to the 7th day of treatment.The length of hospital stay in the three groups was also recorded.Results The comparison of PtCO2 during nebulization among the three groups showed that there were statistically significant differences in the main effect of time and the interaction effect of time and group(P<0.001).The PtCO2 values in the control group showed a linear relationship with time(F=10.166,P=0.003),increasing over time;the PtCO2 values in the experimental group one showed a linear relationship with time(F=10.544,P=0.003),decreasing over time;the PtCO2 values in the experimental group two showed a linear rela-tionship with time(F=20.003,P<0.001),decreasing over time.A one-way ANOVA was conducted on the PtCO2 values at each time point in the three groups.The PtCO2 value at 15 min of nebulization in the control group was higher than that in the experimental group one and the experimental group two.There were statistically signifi-cant differences in the difference in PtCO2 before and after nebulization(dPtCO2)between the experimental group one and the experimental group two and the control group(P<0.05).A one-way ANOVA was conducted on the PtCO2 values at each time point during the observation period after nebulization.The results showed that there were statistically significant differences in PtCO2 at 0 min and 5 min after nebulization among the three groups(P<0.05),while there were no statistically significant differences in PtCO2 at 10 min and 15 min after nebulization among the three groups(P>0.05).The comparison of SPO2 during nebulization among the three groups showed that there were statistically significant differences in the interaction effect of time and group(P<0.05).The SPO2 values in the experimental group one decreased over time.The SPO2 values at 10 min and 15 min of nebulization in the control group were higher than those in the experimental group one and the experimental group two.All three groups could improve PaCO2 in arterial blood gas with the treatment days(P<0.05).Conclusions All three nebu-lization treatment methods can achieve good therapeutic effects.However,non-invasive intermittent oxygen-driven nebulization can increase PtCO2 and SPO2 during nebulization;non-invasive intermittent air-driven nebulization can decrease PtCO2 and SPO2 during nebulization;non-invasive simultaneous air-driven nebulization can decrease PtCO2 and maintain stable SPO2 during nebulization.Therefore,non-invasive simultaneous air-driven nebulization is a relatively safer nebulization inhalation method and is worthy of clinical promotion.

Objective:To compare the dynamic changes of transcutaneous partial pressure of carbon dioxide (PtCO 2) and treatment effect of non-invasive intermittent nebulization and non-invasive simultaneous nebulization in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). Methods:This was a randomized parallel controlled trial study. A total of 70 patients with acute exacerbation of COPD in Changzhou First People′s Hospital from October 2021 to September 2022 were selected by convenience sampling method, and divided into control group and experimental group by randomized digits table method with 35 cases in each group. The control group was given non-invasive intermittent oxygen-driven nebulization, and the experimental group was given non-invasive simultaneous oxygen-driven nebulization. The PtCO 2 values at 0, 5, 10, 15 min (the end point of atomization) of the 2 groups were observed, the daily arterial blood gas analysis indexes (mainly including PaCO 2, PaO 2 and pH) were recorded, and the clinical pulmonary infection score and the self-assessment score of COPD patients were recorded before treatment, on the 4th and 7th day of treatment. Results:Finally, 33 patients were included in both the control group and the experimental group. There were 25 males and 8 females in the control group, aged (75.33 ± 8.24) years old. There were 25 males and 8 females in the experimental group, aged (72.39 ± 8.56) years old. The PtCO 2 values at 0, 5, 10, 15 min in the control group were (63.83 ± 12.47), (64.40 ± 12.57), (65.42 ± 13.77), (66.62 ± 14.59) mmHg (1 mmHg=0.133 kPa). There were statistically significant differences in PtCO 2 at all time points ( F=8.05, P<0.01). Further pairwise comparison by Sidak method showed that there were statistically significant differences in PtCO 2 at 15 min compared with 0, 5, 10 min (all P<0.05). The PtCO 2 values at 0, 5, 10, 15 min in the experimental group were (67.62 ± 11.89), (67.15 ± 12.12), (67.82 ± 12.22), (68.15 ± 12.09) mmHg. There was no statistically significant difference in PtCO 2 at all time points ( F=2.00, P>0.05). The PaCO 2 and pH value of the two groups were improved with the treatment time, the control group had a statistically significant difference on the 4th day of treatment compared with before treatment ( P<0.05), while the experimental group on the second day of treatment compared with before treatment ( P<0.05). Conclusions:Both kinds of nebulization have achieved good therapeutic effects, but non-invasive simultaneous nebulization can better maintain the stability of PtCO 2 in the process of nebulization with higher safety, and can improve the arterial blood gas index PaCO 2 and pH value of patients earlier, which is a more suitable nebulization method for the combination of non-invasive ventilation and nebulization, especially for patients with hypercapnia.

Objective:To explore the effect of "Internet plus" exercise prescription intervention on upper limb dysfunction and quality of life of breast cancer patients at home after surgery, so as to provide reference for health management of breast cancer patients after surgery.Methods:Adopting a prospective randomized controlled trial research method. From November 2021 to January 2023, 124 breast cancer patients in the breast and thyroid surgery department of Xiang′an Hospital Affiliated to Xiamen University were selected for the study. According to the random number table method, they were randomly divided into an intervention group (62 cases) and a control group (62 cases). The control group patients were given routine training, and the intervention group patients received routine training in the first four weeks after operation, and "Internet plus" exercise prescription intervention in the fifth week after operation. The upper limb dysfunction, quality of life before and after the intervention and motor compliance after the intervention between the two groups were compared.Results:A total of 117 patients were ultimately included, and they were all female, with 58 patients in the intervention group aged (51.01 ± 9.77) years old and 59 patients in the control group aged (51.47 ± 9.85) years old. There was no statistically significant difference in upper limb dysfunction and quality of life between the two groups of patients before intervention ( P>0.05). After the intervention, the degree of upper limb dysfunction in the intervention group was (63.55 ± 7.02) points, which were lower than that in the control group (67.13 ± 7.25) points, and the difference was statistically significant ( t = 2.71, P<0.01). After the intervention, the total score of quality of life and the scores of physiological status, social/family status, emotional status, functional status and additional attention of breast cancer patients in the intervention group were (115.27 ± 17.35), (22.65 ± 4.53), (22.79 ± 4.36), (20.96 ± 3.95), (19.56 ± 4.22), (29.31 ± 5.24) points, which were higher than those in the control group (104.28 ± 17.04), (20.57 ± 4.48), (20.85 ± 4.23), (18.75 ± 4.04), (17.18 ± 4.06), (26.93 ± 5.21) points, the differences were statistically significant ( t values were 2.44-3.46, all P<0.05). In terms of exercise compliance of breast cancer patients in the intervention group, the aerobic exercise completion rate was 91.38% (53/58), muscle strength training completion rate was 77.59% (45/58), stretching exercise completion rate was 86.21% (50/58), exercise frequency was (3.96 ± 1.13) times/week, exercise duration was (29.51 ± 7.64) min/time, which was superior to 77.97% (46/59), 57.63% (34/59), 69.49% (41/59), (3.38 ± 0.94) times/week, (23.96 ± 7.33) min/time in the control group, the differences were statistically significant ( χ2 = 4.04, 5.31, 4.73, t = 3.02, 4.01, all P<0.05). Conclusions:"Internet plus" exercise prescription intervention has the characteristics of convenience, intuition and strong operability, which is conducive to improving the upper limb dysfunction, quality of life and exercise compliance of breast cancer patients at home after surgery. It is recommended to be popularized and applied clinically.

Objective To explore the diagnostic value of MRI radiomics model for clinically significant prostate cancer(csPCa)in the transition zone with prostate imaging reporting and data system(PI-RADS)3-4.Methods According to the ratio of prostate cancer(PCa)∶benign prostatic hyperplasia(BPH)=1∶1,the relevant data of patients with transition zone lesions confirmed by pathology were retrospectively collected.Patients were divided into csPCa group and non-csPCa group according to pathological results.Region of interest(ROI)were drawn along the edge of the lesion in T2WI,diffusion weighted imaging(DWI),and apparent diffusion coeffi-cient(ADC)sequences,the radiomics features were extracted,and a single sequence logistic regression model was constructed and validated after feature cleaning and screening.The diagnostic performances of the radiomics model for transition zone csPCa were evaluated and compared.Results A total of 204 patients were included,and there were 94 cases in the csPCa group and 110 cases in the non-csPCa group.There were statistically significant differences in PI-RADS,prostate volume(PV),prostate specific antigen(PSA)and its derivative indicators between csPCa and non-csPCa groups.In the validation set,the area under the cunve(AUC)of the ADC model was 0.766,and the DeLong test showed that the diagnostic performance of the ADC model was significantly higher than that of the DWI and T2WI models.Conclusion When the PI-RADS classification of transition zone lesion is 3-4,the ADC radiomics model has good diag-nostic performance for csPCa,which can reduce unnecessary biopsy in some patients.Radiomics is expected to become a more objec-tive and accurate medical diagnostic tool.

Total knee arthroplasty， as a common treatment option for advanced knee osteoarthritis， can alleviate the clinical symptoms of patients. Deep vein thrombosis of the lower extremity is the most common complication of total knee arthroplasty. Previous studies have shown that the occurrence of deep vein thrombosis after total knee arthroplasty is mostly related to the overexpression of inflammatory factors in vivo. Nuclear transcription factor-κB， Toll-like receptor 4， phosphatidylinositol 3-kinase/protein kinase B， tumor necrosis factor， and nuclear transcription factor E₂-related factor 2 are typical signaling pathways related to inflammation. Regulating the expression of the signaling pathways can intervene the formation of inflammatory factors. Inhibiting the formation of inflammatory factors can help suppress the activation of platelets， thereby blocking thrombosis. According to previous research， Chinese medicine monomers， Chinese medicine extract， and compound Chinese medicine prescriptions all directly or indirectly inhibit the expression of inflammatory factors by regulating the above signaling pathways， thereby suppressing the occurrence of deep vein thrombosis after total knee arthroplasty. Therefore， Chinese medicine can reduce postoperative complications and promote postoperative recovery of patients at low cost with small side effects. This article summarizes the research on Chinese medicine intervention on deep vein thrombosis-related signaling pathways after total knee arthroplasty， which is expected to lay a basis for the in-depth study and clinical application of Chinese medicine in deep vein thrombosis.

OBJECTIVES: Primary trigeminal neuralgia (PTN) is a common cranial nerve disease in neurosurgery, which seriously endangers the physical and mental health of patients. Percutaneous balloon compression (PBC) has become an effective procedure for the treatment of PTN by blocking pain conduction through minimally invasive puncture. However, the recurrence of facial pain after PBC is still a major problem for PTN patients. Intraoperative balloon shape, pressure and compression time can affect the prognosis of patients with PBC after surgery. The foramen ovale size has an effect on the balloon pressure in Meckel's lumen. This study aims to analyse the predictive value of foramen ovale size for postoperative pain recurrence of PBC by exploring the relationship between foramen ovale size and postoperative pain recurrence of PBC. METHODS: A retrospectively analysis was conducted on the clinical data of 60 patients with PTN who were treated with PBC in Department of Neurosurgery, Affiliated Hospital of Chengde Medical College from November 2018 to December 2021. We followed-up and recorded the Barrow Neurological Institute (BNI) pain score at 1, 3, 6 and 12 months after operation. According to the BNI pain score at 12 months after surgery, the patients were divided into a cure group (BNI pain score I to Ⅱ) and a recurrence group (BNI pain score Ⅲ to Ⅴ). The long diameter, transverse diameter and area of foramen ovale on the affected side and the healthy side of the 2 groups were measured. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used for analysis the relationship between the recurrence of pain and the long diameter, transverse diameter, area of foramen ovale on the affected side, and aspect ratio, transverse diameter ratio, area ratio of foramen ovale on the affected side to healthy side in the 2 groups. RESULTS: At the end of 12 months of follow-up, 50 (83.3%) patients had pain relief (the cured group), 10 (16.7%) patients had different degrees of pain recurrence (the recurrence group), and the total effective rate was 83.3%. There were no significant differences in preoperative baseline data between the 2 groups (all P>0.05). The long diameter of foramen ovale on the affected side, the long diameter ratio and area ratio of foramen ovale on the affected/healthy side in the cured group were significantly higher than those in the recurrence group (all P<0.05), and there were no significant differences in the transverse diameter and area of foramen ovale on the affected side and the transverse diameter ratio of foramen ovale on the affected/healthy side between the 2 groups (all P>0.05). The ROC curve analysis showed that the AUC of the long diameter of foramen ovale on the affected side was 0.290 (95% CI 0.131 to 0.449, P=0.073), and the AUC of aspect ratio of foramen ovale on the affected side to healthy side was 0.792 (95% CI 0.628 to 0.956, P=0.004). The AUC of area ratio of foramen ovale on the affected side to healthy side was 0.766 (95% CI 0.591 to 0.941, P=0.008), indicating that aspect ratio and area ratio of foramen ovale on the affected side to healthy side had a good predictive effect on postoperative pain recurrence of PBC. When aspect ratio of foramen ovale on the affected side to healthy side was less than 0.886 3 or area ratio of foramen ovale on the affected side to healthy side was less than 0.869 4, postoperative pain recurrence was common. CONCLUSIONS Accurate evaluation of the foramen ovale size of skull base before operation is of great significance in predicting pain recurrence after PBC.
Humans ; Retrospective Studies ; Foramen Ovale ; Treatment Outcome ; Trigeminal Neuralgia/surgery* ; Pain, Postoperative/etiology* ; Recurrence