A repeating fast radio burst associated with a persistent radio source.

The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium1, which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs2, in at least one case there is evidence for an extreme magneto-ionic local environment3,4 and a compact persistent radio source5. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately [Formula: see text] parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies2,6, far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications.

A fast radio burst source at a complex magnetized site in a barred galaxy.

Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts1-3. Recent observations of a Galactic FRB4-8 suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref. 9). These observations show irregular short-time variation of the Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (AU; Earth-Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy10-12 show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.

A bimodal burst energy distribution of a repeating fast radio burst source.

The event rate, energy distribution and time-domain behaviour of repeating fast radio bursts (FRBs) contain essential information regarding their physical nature and central engine, which are as yet unknown1,2. As the first precisely localized source, FRB 121102 (refs. 3-5) has been extensively observed and shows non-Poisson clustering of bursts over time and a power-law energy distribution6-8. However, the extent of the energy distribution towards the fainter end was not known. Here we report the detection of 1,652 independent bursts with a peak burst rate of 122 h-1, in 59.5 hours spanning 47 days. A peak in the isotropic equivalent energy distribution is found to be approximately 4.8 × 1037 erg at 1.25 GHz, below which the detection of bursts is suppressed. The burst energy distribution is bimodal, and well characterized by a combination of a log-normal function and a generalized Cauchy function. The large number of bursts in hour-long spans allows sensitive periodicity searches between 1 ms and 1,000 s. The non-detection of any periodicity or quasi-periodicity poses challenges for models involving a single rotating compact object. The high burst rate also implies that FRBs must be generated with a high radiative efficiency, disfavouring emission mechanisms with large energy requirements or contrived triggering conditions.

APOBEC mutagenesis, kataegis, chromothripsis in EGFR-mutant osimertinib-resistant lung adenocarcinomas.

BACKGROUND: Studies of targeted therapy resistance in lung cancer have primarily focused on single-gene alterations. Based on prior work implicating apolipoprotein b mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) mutagenesis in histological transformation of epidermal growth factor receptor (EGFR)-mutant lung cancers, we hypothesized that mutational signature analysis may help elucidate acquired resistance to targeted therapies. PATIENTS AND METHODS: APOBEC mutational signatures derived from an Food and Drug Administration-cleared multigene panel [Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT)] using the Signature Multivariate Analysis (SigMA) algorithm were validated against the gold standard of mutational signatures derived from whole-exome sequencing. Mutational signatures were decomposed in 3276 unique lung adenocarcinomas (LUADs), including 93 paired osimertinib-naïve and -resistant EGFR-mutant tumors. Associations between APOBEC and mechanisms of resistance to osimertinib were investigated. Whole-genome sequencing was carried out on available EGFR-mutant lung cancer samples (10 paired, 17 unpaired) to investigate large-scale genomic alterations potentially contributing to osimertinib resistance. RESULTS: APOBEC mutational signatures were more frequent in receptor tyrosine kinase (RTK)-driven lung cancers (EGFR, ALK, RET, and ROS1; 25%) compared to LUADs at large (20%, P < 0.001); across all subtypes, APOBEC mutational signatures were enriched in subclonal mutations (P < 0.001). In EGFR-mutant lung cancers, osimertinib-resistant samples more frequently displayed an APOBEC-dominant mutational signature compared to osimertinib-naïve samples (28% versus 14%, P = 0.03). Specifically, mutations detected in osimertinib-resistant tumors but not in pre-treatment samples significantly more frequently displayed an APOBEC-dominant mutational signature (44% versus 23%, P < 0.001). EGFR-mutant samples with APOBEC-dominant signatures had enrichment of large-scale genomic rearrangements (P = 0.01) and kataegis (P = 0.03) in areas of APOBEC mutagenesis. CONCLUSIONS: APOBEC mutational signatures are frequent in RTK-driven LUADs and increase under the selective pressure of osimertinib in EGFR-mutant lung cancer. APOBEC mutational signature enrichment in subclonal mutations, private mutations acquired after osimertinib treatment, and areas of large-scale genomic rearrangements highlights a potentially fundamental role for APOBEC mutagenesis in the development of resistance to targeted therapies, which may be potentially exploited to overcome such resistance.

[Fat1 inhibits cell proliferation via ERK signaling pathway in esophageal squamous cell carcinoma].

Objective: To clarify the mechanism of Fat1 on the proliferation of esophageal squamous cell carcinoma (ESCC). Methods: KYSE450 cells were transfected with Plko.1-puro-GFP-shRNA-Fat1 plasmid and real time polymerase chain reaction (PCR) was used to verify the efficiency of Fat1 knockdown. The effects of Fat1 and extracellular regulated protein kinase (ERK) pathway inhibitor U0126 on the proliferation of ESCC cells were detected by methyl thiazolyl tetrazolium (MTT). Colony formation assay was used to detect the colony formation ability. Cell cycle was detected by live cell imaging. Western blot was used to observe the level of target protein. Mouse xenograft assay was applied to detect the effect of Fat1 knockdown on KYSE450 cell tumor growth. Immunohistochemistry was used to detect the expressions of related proteins in tumor sections. Results: The efficiency of Fat1 knockdown was (77.1±6.9)% in Fat1 sh1 group and (77.7±7.1)% in Fat1sh2 group. Compared with the control group, the cell proliferation and the expression of p-ERK1/2 were significantly increased in Fat1 sh1 and Fat1sh2 group (P<0.05). After U0126 treatment, the effect of Fat1 knockdown on the proliferation of KYSE450 cells disappeared, and the expression of p-ERK1/2 in KYSE450 cells decreased to a level similar to that in the control group. The number of cell clones in the control group was (72±8), lower than (155±28) and (193±9) in the Fat1sh1 and Fat1sh2 groups, respectively (P<0.05). In KYSE450 cell, division time was shortened from 1 622±32 min in control group to 1 408±29 min in Fat1 sh1 group, the difference was statistically significant (P<0.05). Compared with the control group, the tumor volume of Fat1 knockdown group increased significantly. The tumor weight of control group and Fat1 knockdown group were (0.224±0.028) g and (1.532±0.196) g, respectively, at 4 weeks after inoculation, and the difference was statistically significant (P<0.05). Conclusion: Fat1 inhibits cell proliferation via ERK signaling in ESCC.

How does the two-child policy affect the sex ratio at birth in China? A cross-sectional study.

BACKGROUND: The One-Child Policy led to the imbalance of the sex ratio at birth (SRB) in China. After that, Two-Child Policy was introduced and gradually liberalized at three stages. If both the husband and wife of one couple were the only child of their parents, they were allowed to have two children in policy (BTCP). If only one of them was the only child, they were allowed to have two children in policy (OTCP). The Universal Two-Child Policy (UTCP) allowed every couple to have two children. The objective of this study was to explore the changing trend of SRB at the stages of Two-Child Policy, to analyze the effect of population policy on SRB in terms of maternal age, delivery mode, parity, maternal education, delivery hospital, and to figure out what factors have greater impact on the SRB. METHODS: The data of the study came from Hebei Province Maternal Near Miss Surveillance System, covered the parturients delivered at 28 gestation weeks or more in 22 hospitals from January 1, 2013 to December 31, 2017. We compared the SRB at different policy stages, analyzed the relationship between the SRB and population policy by logistic regression analysis. RESULTS: Total 270,878 singleton deliveries were analyzed. The SRB, 1.084 at BTCP, 1.050 at OTCP, 1.047 at UTCP, declined rapidly (χ2 = 15.97, P < 0.01). With the introduction of Two-Child Policy, the percentage of parturients who were 30-34, ≥35 years old rose significantly, and the percentage of multiparous women increased significantly (40.7, 47.2, 56.6%). The neonatal mortality declined significantly (8.4‰, 6.7‰, 5.9‰, χ2 = 44.49, P < 0.01), the mortality rate of female infant gradually declined (48.2, 43.7, 43.9%). The logistic regression analysis showed the SRB was correlated to the three population policy stages in terms of maternal age, delivery mode, parity, maternal education, delivery hospital. CONCLUSIONS: The SRB has declined to normal level with the gradually liberalizing of Two-Child Policy in China. Advanced maternal age, cesarean delivery, multiparous women, middle level education, rural hospital are the main factors of effect on the decline of the SRB.

[Safety of carotid endarterectomy for the patiets with carotid artery stenosis and coronary artery disease under dual antiplatelet therapy].

Objective: To study the safety of dual antiplatelet therapy prior to carotid endarterectomy in the patients with carotid artery stenosis and Coronary Artery Accident. Methods: We review 86 patients with carotid artery stenosis and Coronary Artery Accidents who admitted in Peking University International Hospital between 2017 January and 2019 March. The 86 patients undergo carotid endarterectomy with dual antiplatelet therapy. We evaluate the safety of carotid endarterectomy dunring the dual antiplatelet thrapy by analyzing the incidence of acute coronary syndrome, ischemic cerebrovascular accident, intracranial hemorrhage, and regional hematoma. Results: From 2017 January to 2019 March, 86 patients with carotid artery stenosis and Coronary Artery Accident continued dual antiplatelet therapy prior to carotid endarterectomy. The incidence of main perioperative complications were as follows: acute coronary syndrome: 0; asymptomatic ischemia cerebrovascular accident: 8.1% (7/86); symptomatic ischemia cerebrovascular accident: 0; intracranial hemorrhage:0; neck hematoma:13.9%(13/86). All the patients were followed 30 days after the procedure. The modify Rakin Scale of the patients were all <3. The local hematoma were all recovered automatically without treatment and the perioperative mortality and morbidity was 0. Conclusion: For the patients with carotid artery stenosis and Coronary Artery Accidents, carotid endarterectomy under dual antiplatelet therapy was a safe choice.

[Simultaneous treatments in patients with severe carotid artery stenosis and coronary artery disease].

Objective: To implement simultaneous treatments in patients with severe carotid artery stenosis and coronary artery disease (CAD), we sought to investigate its efficacy of reducing perioperative major adverse cardiac and cerebrovascular event (MACCE). Methods: Brain-and-Heart treatment team in Peking University International Hospital performed hybrid Digital Substraction Angiography (DSA) of carotid artery and coronary artery for 37 patients meeting the group criterion from September 2017 to February 2019.Twelve patients were diagnosed and received simultaneous treatments of severe carotid artery stenosis and coronary artery disease after hybrid DSA. We conducted the retrospective study and made analysis of these patients. Results: The diagnosis rate by simultaneous treatmentsin patients with carotid artery stenosis and coronary artery disease is 59.5% (22/37), the rate of severe carotid artery stenosis or multi-vessel CAD is 77.3% (17/22).The rate of severe carotid artery stenosis with CAD is 54.5% (12/22), therate of simultaneous treatmentsis 83.3%(10/12). Nine patients post-operative symptoms release, one patient with ischemic stroke after CABG, and two patients of medical therapy with stable symptoms. Conclusion: Simultaneous treatments in patients with severe carotid artery stenosis and coronary artery disease not only reveal the positive correlation between carotid stenosis and CAD, but also accurately evaluate severity degree or rapidly formulate scheme and reduce MACCE.

[Application of combined angiography in diagnosis and treatment of carotid artery stenosis].

Objective: To evaluate the safety and clinical value of combined cardiac and cerebral angiography in the diagnosis and treatment of patients with carotid artery stenosis. Methods: Clinical data of patients from May 2016 to June 2019 were collected. The patient underwent combined angiography under local anesthesia. Clinical characteristics, prognosisand complications were retrospectively analyzed. Results: A total of 45 patients with carotid artery stenosis received combined angiography, among which 12 patients had no obvious carotid artery stenosis. There were 22 cases with unilateral carotid artery stenosis, including 12 cases with mild stenosis and 10 cases with moderate to severe stenosis. There were 11 cases of bilateral stenosis, including 3 cases with mild stenosis and 8 cases with moderate to severe stenosis. 12 patients had no obvious stenosis incoronary arteries, 11 patients had single-vessel disease, 7 patients had 2-vessel disease, and 15 patients had 3-vessel disease. In the whole group of patients, surgical indications are available of 18 patients with carotid artery stenosis, 4 of the mreceived combined therapy. 2 of them under went Carotid Endarterectomy (CEA)+Percutaneous Transluminal Coronary Intervention (PCI), 2 under went Carotid Artery Stenting (CAS)+PCI. CAS+coronary artery angiography was performed in 3 cases. CEA+coronary angiography was performed in 5 cases. 5 patients received conservative treatment after combined angiography. In one case, the condition of coronary artery was so complicated that PCI was performed firstly. No cardiac or cerebrovascular complications such as myocardial infarction or cerebral infarction occurred during perioperative period. Conclusion: Combined cardio-cerebrovascular angiography is a good method to evaluate the cardiovascular and cerebrovascular in the diagnosis and treatment of patients with carotid artery stenosis, which can provide a clear diagnosis for treatment with a low complications frequency.

[Adenocarcinoma in a Meckel's diverticulum with multiple liver metastases and gastrointestinal hemorrhage: a case report].

Meckel's diverticulum is the most common congenital anomaly of the gastrointestinal tract, affecting approximately 2% of the population. It is a true diverticulum occurring on the anti-mesenteric border of the distalileum, typically within 100 cm of the ileo-caecal valve. Neoplasms arising in Meckel's diverticula are uncommon, and those reported in the literature are mainly carcinoid tumors, followed by gastrointestinal stromal tumors (GIST) and benign leiomyomas. Adenocarcinomas are extremely rare. Tumors in Meckel's present non-specifically with gastrointestinal complaints, such as bleeding, obstruction, inflammation or perforation. The suspicion of a Meckel's tumor is often not thought of at the initial. In this article we describe a 57-year-old woman who presented with massive rectal bleeding and severe anemia, later found to be caused by a adenocarcinoma arising from Meckel's diverticulum. The tumor was unfortunately highly aggressive. Multiple liver metastases had already existed when we discovered the primary mass. Later we performed a partial resection of the ileumto cease the bleeding. Meckel's diverticulum and the tumor were resected simultaneously. The pathological diagnosis confirmed adenocarcinoma arising from the Meckel's diverticulum. The final stage was pT4NxM1, stage IV according to the Union for International Cancer Control (UICC) classification. After operation we gave the patient first-line, mFOLFOX6 chemotherapy, but it turned out to be not effective. Rapid progress of the liver metastases and suspicion of multiple lung metastasis in short time after therapy indicated a bad outcome. We believe this is the first case of adenocarcinoma in a Meckel's diverticulum to be reported in domestic literature. The diagnosis of Meckel's tumor should be considered as inpatients'acute gastrointestinal complaints; when found incidentally at laparotomy, it should be carefully examined for any gross abnormality and resection should be considered.

Geography has a greater effect than Wolbachia infection on population genetic structure in the spider mite, Tetranychus pueraricola.

Wolbachia is an intracellular symbiotic bacterium that infects various spider mite species and is associated with alterations in host reproduction, which indicates the potential role in mite evolution. However, studies of Wolbachia infections in the spider mite Tetranychus pueraricola, a major agricultural pest, are limited. Here, we used multilocus sequence typing to determine Wolbachia infection status and examined the relationship between Wolbachia infection status and mitochondrial diversity in T. pueraricola from 12 populations in China. The prevalence of Wolbachia ranged from 2.8 to 50%, and three strains (wTpue1, wTpue2, and wTpue3) were identified. We also found double infections (wTpue1 + wTpue3) within the same individuals. Furthermore, the wTpue1 strain caused weak cytoplasmic incompatibility (CI) (egg hatchability ~55%), whereas another widespread strain, wTpue3, did not induce CI. There was no reduction in mitochondrial DNA (mtDNA) or nuclear DNA diversity among infected individuals, and mtDNA haplotypes did not correspond to specific Wolbachia strains. Phylogenetic analysis and analysis of molecular variance revealed that the distribution of mtDNA and nuclear DNA haplotypes were significantly associated with geography. These findings indicate that Wolbachia infection in T. pueraricola is complex, but T. pueraricola genetic differentiation likely resulted from substantial geographic isolation.

Serum microRNA-135a downregulation as a prognostic marker of non-small cell lung cancer.

Abnormal expression of microRNA-135a (miR-135a) is closely associated with oncogenesis. However, the relationship between serum miR-135a levels and the clinical parameters and prognosis of non-small cell lung cancer (NSCLC) remain unclear. The study aimed to investigate the clinical significance of serum miR-135a expression in patients with NSCLC. miR-135a expression was analyzed by real-time PCR and its correlation with NSCLC was determined by various statistical methods for 104 NSCLC patients and 40 healthy volunteers. The serum miR-135a level was significantly lower in NSCLC patients than in healthy control subjects (P < 0.01), and was closely related to distant metastasis (P < 0.015), lymphatic metastasis (P = 0.000), TNM (tumor node metastasis) stage (P = 0.001), and pathological stage (P = 0.021) of NSCLC. The five year overall survival was significantly lower in patients with low miR-135a expression than that in patients with high serum miR-135a levels (P = 0.010). Multivariate analysis showed that serum miR-135a level could be treated as an independent risk factor for NSCLC prognosis (P = 0.011). In conclusion, the serum miR-135a level was downregulated in NSCLC patients, and was associated with poor prognosis. Additionally, it can be used as a biomarker for NSCLC prognosis.

Structural and biochemical characteristics of chitin-binding protein SeCBP66 from Spodoptera exigua (Hübner).

Peritrophic membrane proteins are important components of the insect peritrophic membrane. A novel cDNA gene encoding a chitin-binding protein, named secbp66, was identified by immunization screening of the cDNA library of Spodoptera exigua. The full length of secbp66 is 1806 bp, which encodes 602 amino acids. The predicted weight of the protein is 64.2 kDa. Bioinformatic analysis showed that a signal peptide composed of 17 amino acids located at the N-terminal of SeCBP66 contained seven tandem putative Type-II functional chitin-binding domains and five potential N-glycosylation sites, but no O-linked glycosylation sites. To study the properties of SeCBP66, recombinant SeCBP66 was successfully expressed in the insect cell line BTI-Tn-5B1-4 with a Bac-to-Bac expression system. A chitin binding experiment showed that the recombinant SeCBP66 protein could bind to chitin strongly. This study of the novel chitin-binding protein SeCBP66 provides a basis for developing new control targets for S. exigua.

[Analysis on risk factors of screen time among Chinese primary and middle school students in 12 provinces].

OBJECTIVE: To investigate the characteristics of screen time and its risk factors in Chinese primary and middle school students. METHODS: During April 2012 and June 2012, according to the geographical distribution, the stratified random cluster sampling method was used to select 4 provinces from eastern, central and western China, respectively. The convenience sampling method was used to select 2 primary and middle schools from urban, 2 primary and middle schools from rural in each province. In each school, all grades were included, and 2 classes were selected in each grade. A total of 51 866 students or parents were selected as study participants, and 43 771 questionnaires were valid. Information on demographics, academic performance, screen time (TV, computer and cellphone) at weekdays and weekends and the prevalence of the high screen time were compared, multivariate logistic regression was used to analyze the association between screen time >2 h/d and potential influential factors. RESULTS: The percentage of students with screen time >2 h/d at weekdays and weekends were 16.2% (7 082/43 771) and 41.5% (18 141/43 771) (χ(2)=6 280.14, P<0.001), respectively. The distribution of P50 (P25-P75) for screen time at weekdays and weekends were 0.9(0.4-1.6) and 1.8(1.0-3.0) (Z=-131.26, P<0.001), respectively. The results of multinomial logistic regression analysis showed that, at weekdays, subjects characterized as primary school students, boys, urban area, living in western area and sufficient vigorous physical activity ≤2 d/w had higher risk for screen time >2 h/d than those characterized as elementary school students, girls, rural area, living in eastern area and sufficient vigorous physical activity >3 d/w, odds ratio were 2.01, 1.54, 1.21, 1.09, and 1.07, respectively (P<0.05 for all); subjects characterized as a normal or worse self rating academic performance had higher risk for screen time >2 h/d than those characterized as a good self rating academic performance, odds ratioes were 1.24 and 1.73, respectively (P<0.05 for all); subjects characterized as paternal education level as elementary school, middle school, high school or secondary school had higher risk for screen time >2 h/d than those characterized as paternal education level as college school or high, odds ratioes were 1.41, 1.47 and 1.52, respectively (P<0.05 for all); subjects characterized as maternal education level as elementary school, middle school and high school or secondary school had higher risk for screen time >2 h/d than those characterized as maternal education level as college, odds ratioes were 1.40, 1.52 and 1.47, respectively (P<0.05 for all). At weekends, subjects characterized as primary school students, boys, urban area and sufficient vigorous physical activity ≤2 d/w had higher risk for screen time >2 h/d than those characterized as elementary school students, girls, rural area and sufficient vigorous physical activity >3 d/w, odds ratioes were 2.11, 1.51, 1.20 and 1.05, respectively (P<0.05 for all). At weekends, subjects characterized as a normal or worse self rating academic performance had higher risk for screen time >2 h/d than those characterized as a good self rating academic performance, odds ratioes were 1.09 and 1.26, respectively (P<0.05 for all); subjects characterized as paternal education level as elementary school, middle school, high school or secondary school had higher risk for screen time >2 h/d than those characterized as paternal education level as college school or high, odds ratioes were 1.29, 1.30 and 1.19, respectively (P<0.05 for all); subjects characterized as maternal education level as elementary school, middle school had higher risk for screen time >2 h/d than those characterized as maternal education level as college school or high, odds ratioes were 1.19 and 1.16 and, respectively (P<0.05 for all). CONCLUSION: The prevalence of screen time >2 h/d is high; screen time at weekdays is longer than weekends, and there are significant differences among different sexes, urban or rural areas, living areas, self rating academic performance, parents education levels and physical activity groups.

How do hosts react to endosymbionts? A new insight into the molecular mechanisms underlying the Wolbachia-host association.

Wolbachia is an intracellular bacterium that has aroused intense interest because of its ability to alter the biology of its host in diverse ways. In the two-spotted spider mite, Tetranychus urticae, Wolbachia can induce complex cytoplasmic incompatibility (CI) phenotypes and fitness changes, although little is known about the mechanisms. In the present study, we selected a strain of T. urticae, in which Wolbachia infection was associated with strong CI and enhanced female fecundity, to investigate changes in the transcriptome of T. urticae in Wolbachia-infected vs. uninfected lines. The responses were found to be sex-specific, with the transcription of 251 genes being affected in females and 171 genes being affected in males. Some of the more profoundly affected genes in both sexes were lipocalin genes and genes involved in oxidation reduction, digestion and detoxification. Several of the differentially expressed genes have potential roles in reproduction. Interestingly, unlike certain Wolbachia transinfections in novel hosts, the Wolbachia-host association in the present study showed no clear evidence of host immune priming by Wolbachia, although a few potential immune genes were affected.

Effect of Ginkgo biloba extract on matrix metalloproteinase-3 expression in a rat model of chondrocyte injury.

A rat model with cartilage chondrocyte injury was established using interleukin-1ß (IL-1ß) to investigate the effect of Ginkgo biloba extract (EGb) on matrix metalloproteinase-3 (MMP-3) expression. Rat chondrocytes were extracted and randomly divided into six groups: control group, IL-1ß (model) group, IL-1ß + dexamethasone group, and IL-1ß + EGb group (both high and low dose groups). Reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay were used to detect MMP-3 expression. Compared to the MMP-3 mRNA level in the control group, MMP-3 mRNA level significantly increased in the model group (P < 0.05). The application of dexamethasone or EGb significantly decreased the MMP-3 mRNA level (P < 0.05). MMP-3 mRNA and protein levels decreased in the EGb-treated group, especially in the high-dose group, compared to those in the dexamethasone group (P < 0.05). EGb may reduce MMP-3 production during IL-1ß-induced chondrocyte damage and protect chondrocytes to some extent, with better efficacy at high doses.

A simple empirical model for the clarification-thickening process in wastewater treatment plants.

In wastewater treatment plants (WWTPs), activated sludge is thickened in secondary settling tanks and recycled into the biological reactor to maintain enough biomass for wastewater treatment. Accurately estimating the activated sludge concentration in the lower portion of the secondary clarifiers is of great importance for evaluating and controlling the sludge recycled ratio, ensuring smooth and efficient operation of the WWTP. By dividing the overall activated sludge-thickening curve into a hindered zone and a compression zone, an empirical model describing activated sludge thickening in the compression zone was obtained by empirical regression. This empirical model was developed through experiments conducted using sludge from five WWTPs, and validated by the measured data from a sixth WWTP, which fit the model well (R² = 0.98, p < 0.001). The model requires application of only one parameter, the sludge volume index (SVI), which is readily incorporated into routine analysis. By combining this model with the conservation of mass equation, an empirical model for compression settling was also developed. Finally, the effects of denitrification and addition of a polymer were also analysed because of their effect on sludge thickening, which can be useful for WWTP operation, e.g., improving wastewater treatment or the proper use of the polymer.