LINC00240/miR-155 axis regulates function of trophoblasts and M2 macrophage polarization via modulating oxidative stress-induced pyroptosis in preeclampsia.

BACKGROUND: This study aimed to investigate the effects of LINC00240/miR-155/Nrf2 axis on trophoblast function and macrophage polarization in the pathogenesis of preeclampsia. METHODS: Bindings between LINC00240, miR-155 and Nrf2 were validated by dual luciferase reporter assay or RNA-immunoprecipitation. Cell proliferation, migration, invasion, and pyroptosis were detected by CCK-8, clone formation, wound healing, Transwell system, and flow cytometry, respectively. Macrophage polarization was tested by flow cytometry. The expression levels of LINC00240, miR-155, Nrf2, and oxidative stress and pyroptosis-related markers in in vitro and in vivo preeclampsia models were analyzed by qPCR, western blot, or ELISA assays. Blood pressure, urine protein levels, liver and kidney damages, and trophoblast markers in placenta tissues were further studied in vivo. RESULTS: Placenta tissues from preeclampsia patients and animals showed decreased LINC00240 and Nrf2 and increased miR-155 expression levels, and the decreased M2 macrophage polarization. LINC00240 directly bound and inhibited expression of miR-155, which then inhibited oxidative stress-induced pyroptosis, promoting proliferation, migration and invasion abilities of trophoblasts, and M2 macrophage polarization. Inhibition of miR-155 led to increased Nrf2 expression and similar changes as LINC00240 overexpression in trophoblast function and macrophage polarization. Overexpression of LINC00240 in in vivo preeclampsia model decreased blood pressure, urine protein, liver and kidney damages, increased fetal weight and length, and induced trophoblast function and M2 macrophage polarization. CONCLUSION: LINC00240 inhibited symptoms of preeclampsia through regulation on miR-155/Nrf2 axis, which suppressed oxidative stress-induced pyroptosis to improve trophoblast function and M2 macrophage polarization. LINC00240 could be a potential therapeutic target for preeclampsia.

Three-Dimensional Reduced Graphene Hydrogels Using Various Carbohydrates for High Performance Supercapacitors.

In present work, three-dimensional (3D) reduced graphene hydrogels (RGHs) are prepared through an efficient and facile strategy by employing three types of carbohydrates (glucose, fructose and sucrose) as reducing agents in aqueous solution of graphene oxide (GO) with ammonia. The formation of RGHs could be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The structures and porosity were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and N2 sorption experiments. Benefiting from the abundant porous architectures as fast ionic channels for electrochemical energy storage, the prepared RGHs exhibited a high specific capacitance up to 153.5, 145.0 and 150.3 F g−1 at 0.3 A g−1 for FRGHs (fructose), GRGHs (glucose) and SRGHs (sucrose), which can be maintained for 61.4, 61.5 and 46.9% as the discharging current density was increased up to 20 A g−1. Moreover, it also showed that the electrode based on RGHs has good electrochemical stability and high degree of reversibility in the charge/discharge cycling test.

Detection of serum major histocompatibility complex I (HLA-1) and ß2-microglobulin (ß2M) in pre-eclampsia using isobaric tags for relative and absolute quantitation (iTRAQ).

OBJECTIVE: The purpose of this preliminary investigation into the pathogenesis of pre-eclampsia was to screen the differential proteins in the serum of pregnant women with normal pregnancy and early-onset pre-eclampsia using isobaric tags for relative and absolute quantitation (iTRAQ), so as to identify serum biomarkers for the early diagnosis of pre-eclampsia. METHODS: We examined the peripheral serum of 58 normal pregnant women and 42 pregnant women with early-onset pre-eclampsia using iTRAQ; the differentially expressed proteins were screened for bioinformatics analysis; and the expression of candidate proteins human leukocyte antigen-1 (HLA-1) and ß2-microglobulin (ß2M) in placental tissues was detected using western blot. RESULTS: We identified a total of 63 differential proteins in the serum of patients from the normal control group and the pre-eclampsia group, and this included 24 up-regulated proteins and 39 down-regulated proteins. The western blot results of placental tissue showed reduced HLA-1 expression (1.12 ± 0.23) in the placenta in the pre-eclampsia group as compared with the normal control group (1.34 ± 0.22). Consistent with the results observed in the serum, ß2M in the placenta in the pre-eclampsia group was significantly elevated (1.05 ± 0.47) in comparison with the normal group (0.75 ± 0.33) (P < 0.05). CONCLUSION: In this study, we found that iTRAQ technology was useful for identifying differentially expressed proteins in the peripheral serum of pregnant women with pre-eclampsia, and that HLA-1 and ß2M, which may be involved in the occurrence of pre-eclampsia, show promise as predictive markers of pre-eclampsia.

Computer-assisted three-dimensional individualized extreme liver resection for hepatoblastoma in proximity to the major liver vasculature.

BACKGROUND: The management of hepatoblastoma (HB) becomes challenging when the tumor remains in close proximity to the major liver vasculature (PMV) even after a full course of neoadjuvant chemotherapy (NAC). In such cases, extreme liver resection can be considered a potential option. AIM: To explore whether computer-assisted three-dimensional individualized extreme liver resection is safe and feasible for children with HB who still have PMV after a full course of NAC. METHODS: We retrospectively collected data from children with HB who underwent surgical resection at our center from June 2013 to June 2023. We then analyzed the detailed clinical and three-dimensional characteristics of children with HB who still had PMV after a full course of NAC. RESULTS: Sixty-seven children diagnosed with HB underwent surgical resection. The age at diagnosis was 21.4 ± 18.8 months, and 40 boys and 27 girls were included. Fifty-nine (88.1%) patients had a single tumor, 39 (58.2%) of which was located in the right lobe of the liver. A total of 47 patients (70.1%) had PRE-TEXT III or IV. Thirty-nine patients (58.2%) underwent delayed resection. After a full course of NAC, 16 patients still had close PMV (within 1 cm in two patients, touching in 11 patients, compressing in four patients, and showing tumor thrombus in three patients). There were 6 patients of tumors in the middle lobe of the liver, and four of those patients exhibited liver anatomy variations. These 16 children underwent extreme liver resection after comprehensive preoperative evaluation. Intraoperative procedures were performed according to the preoperative plan, and the operations were successfully performed. Currently, the 3-year event-free survival of 67 children with HB is 88%. Among the 16 children who underwent extreme liver resection, three experienced recurrence, and one died due to multiple metastases. CONCLUSION: Extreme liver resection for HB that is still in close PMV after a full course of NAC is both safe and feasible. This approach not only reduces the necessity for liver transplantation but also results in a favorable prognosis. Individualized three-dimensional surgical planning is beneficial for accurate and complete resection of HB, particularly for assessing vascular involvement, remnant liver volume and anatomical variations.

Computer-assisted rescue of the inferior mesenteric artery in a child with a giant ganglioneuroblastoma: A case report.

BACKGROUND: Ganglioneuroblastoma (GNB) is a peripheral neuroblastoma (NB) with malignant degree between highly malignant NB and benign ganglioma (GN). Pathology is the gold standard of diagnosis. Although GNB is not uncommon in children, biopsy alone may lead to an inaccurate diagnosis, especially for giant tumors. However, surgical resection may be associated with significant complications. Here, we report a case of computer-assisted surgical resection of a giant GNB in a child and successful rescue of the inferior mesenteric artery. CASE SUMMARY: A 4-year-old girl was admitted to our department for a giant retroperitoneal lesion, which was considered to be an NB by her local hospital. The symptoms of the girl disappeared spontaneously without treatment. On physical examination, a mass of about 10 cm × 7 cm could be palpated in her abdomen. Ultrasonography and contrast-enhanced computed tomography performed in our hospital also showed an NB, and there was a very thick blood vessel inside the tumor. However, aspiration biopsy revealed GN. Surgical resection is the best treatment option for this giant benign tumor. For precise preoperative evaluation, three-dimensional reconstruction was performed. It was clear that the tumor was close to the abdominal aorta. The superior mesenteric vein was pushed forward, and the inferior mesenteric artery passed through the tumor. Because GN generally does not invade blood vessels, we split the tumor with a CUSA knife during the operation and found that there was indeed a straight and intact vascular sheath. Arterial pulsation was observed in the completely exposed inferior mesenteric artery. The pathologists interpreting the tissue finally diagnosed it as a mixed GNB (GNBi), which is more malignant than GN. However, both GN and GNBi usually have a good prognosis. CONCLUSION: This was a case of successful surgical resection of a giant GNB, and aspiration biopsy underestimated the pathological staging of the tumor. Preoperative three-dimensional reconstruction assisted with the radical resection of the tumor and rescue of the inferior mesenteric artery.

The effect of 2n gametes on sex ratios in Actinidia.

Sex can sometimes lead to complications. In some crops, 2n gametes have been exploited by plant breeders to transfer genetic variation between taxa of different ploidy levels. However, their role and use in dioecious genera have received relatively little attention. In the dioecious genus Actinidia (kiwifruit), seedling populations usually segregate equally for females and males as sex is determined by an XX female/XY male system. While fertilization involving 2n egg cells is not expected to affect the sex ratios of progenies, fertilization involving 2n pollen is likely to produce progenies with excess males. The extent of sex ratio distortion will depend on the relative contributions of first and second division restitution, and the frequency and location of cross-overs in meiosis. In this study, seedlings recovered from crosses between females of hexaploid Actinidia deliciosa and males of two diploid species, Actinidia chinensis and Actinidia eriantha, included a proportion of pentaploid hybrids presumably derived from fertilization involving 2n pollen. Most of these pentaploids were male, and a proportion of them were likely to be carrying two Y chromosomes. If used as parents in further crosses, males with multiple Y chromosomes are likely to cause distorted sex ratios in their immediate progenies. In dioecious genera such as Actinidia, the effects on sex ratios of different mechanisms of ploidy change need to be taken into account when considering the evolution of polyploidy and the design of breeding strategies involving ploidy manipulation.

Photo-excitation production of medically interesting isomers using intense γ-ray source.

Photon-induced nuclear excitation (i.e. photo-excitation) can be used for production of nuclear isomers, which have potential applications in astrophysics, energy storage, medical diagnosis and treatment. This paper presents a feasibility study on photo-excitation production of four nuclear isomers (103mRh, 113m,115mIn and 176mLu) with intense γ-ray source based on laser-electron Compton scattering (LCS). The decay properties of these isomers and their potential applications in medical diagnosis and treatment were reviewed. The cross-section curve, simulated yield and activity of product of each photo-excitation process were calculated. The cutoff energy of LCS γ-ray beam was optimized by adjusting electron beam energy in order to maximize the isomer activity. It is found that the specific activity of the above-mentioned isomers can exceed ~0.2 GBq/g for 6-h target irradiation at an intensity of 1013 γ/s. Our simulation results suggest the prospect of producing medically interesting radionuclides with photo-excitation using the state-of-art LCS γ-ray beam facility.

Natural hybridization between Rhododendron delavayi and R. cyanocarpum (Ericaceae), from morphological, molecular and reproductive evidence.

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. In field observations, it was noted that the putative hybrids between R. delavayi Franch. and R. cyanocarpum (Franch.) Franch. ex W.W. Sm. had intermediate morphologies. On the basis of morphology, chloroplast DNA (trnL-rpl32) and nuclear DNA (waxy), hybrids and parental species were identified. Hybridization occurred in both directions, but was asymmetrical, with R. delavayi as the major maternal parent. Reciprocal hand pollination treatments showed that either species, as pollen donor or pollen receiver, could produce fruits. It was noted that fruit set varied among treatments. The same pollinators (bumblebees) were shared in both parental species. From these results, we conclude that individuals with intermediate morphologies are indeed of hybrid origin from natural hybridization between R. cyanocarpum and R. delavayi. Furthermore, we presume the hybridization at the study site could have been initiated by habitat disturbance in the 1950s, and we may hence witness the early stages of hybrid swarm formation.

LncRNA MALAT1 regulates trophoblast cells migration and invasion via miR-206/IGF-1 axis.

Preeclampsia (PE) is a pregnancy-specific syndrome that substantially leads to maternal and fetal mortality. Multiple factors contribute to the disease, but the exact pathogenesis still remains elusive. Here we explored the roles of lncRNA MALAT1 and miR-206 in PE. qRT-PCR was applied to measure mRNA levels of MALAT1 and miR-206 in the placenta of PE patients. Scratch wound healing assay and transwell invasion assay were conducted to test the effects of MALAT1 and miR-206 on migration and invasion of trophoblast cells. In addition, we validated MALAT1/miR-206 and miR-206/IGF-1 interactions with dual luciferase reporter assay. Western bot was used to detect protein expressions of IGF-1, p-PI3K, PI3K, p-Akt and Akt. We found that MALAT1 was decreased but miR-206 was increased in the placenta of patients with PE. Inhibition of MALAT1, knockdown IGF-1, or miR-206 mimics suppressed the trophoblast cells migration and invasion, while overexpression of MALAT1, IGF-1 or miR-206 inhibitors exhibited opposite effects. Further, miR-206 was confirmed as a direct target of MALAT1. Besides, miR-206 inhibited IGF-1 expression by directly binding to the 3'UTR. Mechanistically, our study demonstrated that MALAT1 regulates IGF-1/PI3K/Akt signaling via miR-206. Together, these results suggest that MALAT1 and miR-206 play important roles in PE. MALAT1 regulates miR-206/IGF-1 axis, thereby modulating trophoblast cells migration and invasion through PI3K/Akt signal pathway. These results show light on the underlying mechanisms of PE and provide potential targets for PE therapy.Abbreviations: PE: Preeclampsia; lncRNA: Long-non-coding RNA; MALAT1: Metastasis-associated lung adenocarcinoma transcript 1; IGF-1: Insulin-like growth factor 1; PI3k: Phosphatidylinositol-4, 5-bisphosphate 3-kinase; Akt: Protein kinase B; GAPDH: Glyceraldehyde 3-phosphate dehydrogenase; qRT-PCR: Quantitative Reverse Transcription polymerase chain reaction; shRNA: Short hairpin RNA; siRNA: Small interfering RNA; EMT: Epithelial-mesenchymal transition.

[Economic loss of nosocomial infections in patients with cerebral hemorrhage or cerebral infarction].

OBJECTIVE: To evaluate the economic loss of nosocomial infections (NI) in patients with cerebral hemorrhage or cerebral infarction. METHODS: We used case-control method to compare the medical expenses between 46 pairs of cerebral hemorrhage or cerebral infarction patients with or without NI. RESULTS: The median hospital stay, total treatment expense, medications expense, examination expense, and treatment expense of NI were significantly higher in the NI group than in non-NI group (all P < 0.01 ). CONCLUSIONS: NI can prolong hospital stay and increase medical expenses of patients with cerebral hemorrhage or cerebral infarction. Effective measures should be taken to control NI.

[Current situation and control strategy of nosocomial infection in intensive care unit].

Intensive care unit (ICU) is a place with high risk of nosocomial infections. Effective control of nosocomial infections in ICU brings both social and economic benefits. This article summarizes ten main points in the control strategy of ICU infections.

Liver Fibrosis Can Be Induced by High Salt Intake through Excess Reactive Oxygen Species (ROS) Production.

High salt intake has been known to cause hypertension and other side effects. However, it is still unclear whether it also affects fibrosis in the mature or developing liver. This study demonstrates that high salt exposure in mice (4% NaCl in drinking water) and chick embryo (calculated final osmolality of the egg was 300 mosm/L) could lead to derangement of the hepatic cords and liver fibrosis using H&E, PAS, Masson, and Sirius red staining. Meanwhile, Desmin immunofluorescent staining of mouse and chick embryo livers indicated that hepatic stellate cells were activated after the high salt exposure. pHIS3 and BrdU immunohistological staining of mouse and chick embryo livers indicated that cell proliferation decreased; as well, TUNEL analyses indicated that cell apoptosis increased in the presence of high salt exposure. Next, dihydroethidium staining on the cultured chick hepatocytes indicated the excess ROS was generated following high salt exposure. Furthermore, AAPH (a known inducer of ROS production) treatment also induced the liver fibrosis in chick embryo. Positive Nrf2 and Keap1 immunohistological staining on mouse liver suggested that Nrf2/Keap1 signaling was involved in high salt induced ROS production. Finally, the CCK8 assay was used to determine whether or not the growth inhibitory effect induced by high salt exposure can be rescued by antioxidant vitamin C. Meanwhile, the RT-PCR result indicated that the Nrf2/Keap1 downsteam genes including HO-1, NQO-1, and SOD2 were involved in this process. In sum, these experiments suggest that high salt intake would lead to high risk of liver damage and fibrosis in both adults and developing embryos. The pathological mechanism may be the result from an imbalance between oxidative stress and the antioxidant system.

High salt intake negatively impacts ovarian follicle development.

Many human disorders induce high salinity in tissues and organs, interfering with their normal physiological functions. Using a mouse model, we demonstrated that high salt intake caused infertility. Specifically, we established that high salinity dramatically affects ovarian follicle development and the extent of follicular atresia. However, it did not significantly influence the primordial follicles. TUNEL assays revealed that high salt intake inhibited follicle development by inducing the granulosa and theca cells that surround the oocytes to undergo apoptosis. Furthermore, immunohistological staining for the proliferation markers Ki67 and PH3 showed that high salt intake also repressed granulosa cell proliferation. In vitro testing of granulosa cells also confirmed that high salt significantly repressed cell proliferation and promoted cell apoptosis. In summary, high salt consumption negatively impacts reproductive functions in female mice by interfering with ovarian folliculogenesis.

[Gene diagnosis of facioscapulohumeral muscular dystrophy].

OBJECTIVE: To observe the characteristics of changes of p13E-11 labelled 4q35 EcoRI fragments and to make a gene diagnosis of facioscapulohumeral muscular dystrophy(FSHD). METHODS: Genomic DNA was extracted and was digested by EcoR I /Bln I. After pulsed field gel electrophoresis, it was hybridized with probe p13E-11 by Southern blot. The illness was diagnosed as FSHD when the 4q35 EcoRI fragment was smaller than 38 kb. RESULTS: In 26 cases of FSHD, the fragments of 20 cases were smaller than 38 kb. The positive rate was 76.92%. In 12 cases of FSHD family members, the fragments of 2 cases were smaller than 38 kb. All fragments of the 21 controls were greater than 38 kb. CONCLUSION: It was rather good to use <38 kb as a standard for diagnosis of FSHD. The positive rate of FSHD was similar to that from the references.

[Role of cytokeratin expression in differential diagnosis of intraductal proliferative lesions of breast].

OBJECTIVE: To evaluate the expression of cytokeratins in intraductal proliferative lesions of breast, including usual ductal hyperplasia (UDH), atypical ductal hyperplasia (ADH), ductal carcinoma-in-situ (DCIS) and its role in differential diagnosis. METHODS: Ninety two cases of paraffin-embedded lesional breast tissue, 30 cases of frozen samples, cell cultures of hyperplastic ductal cells and 2 invasive ductal carcinoma cell lines (T47D and MCF-7) were used for this study. Immunohistochemistry was performed using EnVision method for 34betaE12, CK8 and CK14. RESULTS: The percentage of 34betaE12-positivity in paraffin-embedded samples of UDH, ADH, DCIS and invasive ductal carcinoma (IDC) was found to be 95.2%, 33.3%, 19.2% and 12.5% respectively. In frozen tissues, all UDH cases and 55% of IDC cases expressed 34betaE12. The primary UDH cell cultures and T47D cell line were also 34betaE12-positive, whereas MCF7 cell line showed negative staining. The expression rate of CK8 and CK14 in UDH was also different from that in ADH and DCIS. CONCLUSIONS: 34betaE12 can be useful in differential diagnosis of intraductal proliferative lesions of the breast. However application of this cytokeratin stain in intraoperative frozen sections is relatively limited. The expression patterns of CK8 and CK14 are also helpful in the differential diagnosis of similar lesions.

Selective recognition of sulfate anions in a 95% ethanol solvent with a simple neutral salicylaldehyde dansyl hydrazine Schiff base tuned by Brønsted-Lowry acid-base reaction.

A new Schiff base compound, 5-(dimethylamino)-N'-(2-hydroxybenzylidene)naphthalene-1-sulfonohydrazide (R), has been synthesized, characterized, and employed as a selective fluorescence receptor for the recognition of sulfate anions. UV-vis absorption, fluorescence emission, (1)H NMR spectra and DFT calculation studies on the system have been carried out to determine the nature of the interactions between R and anions. The results reveal that the deprotonation of the phenol without the need of a strong base leads to the formation of a hydrogen-bonding complex with a -SO2-NH- group, which is responsible for the spectra changes. The deprotonation process for the selectivity recognition of sulfate can be tuned by the Brønsted-Lowry acid-base reaction in nonaqueous solutions, revealing that suitable phenolic hydroxyl acidity is the key factor for anion recognition selectivity.

Effect of experiential health education on diet control of college students with type 2 pre diabetes mellitus / 中国学校卫生

Objective@#To understand the influence of experiential health education on diet control of college students with pre diabetes mellitus, and to provide reference for healthy eating habits promotion among college students.@*Methods@#According to the method of random number table, 78 pre diabetic college students screened from Changzhi Medical College from September 2020 to June 2021 were randomly assigned to observation group and control group (39 students in each group). The control group received routine health education for 10 months, once a week for 1 hour each time; On the basis of the above, the observation group received experiential health education once a week for 1 hour, including diet experience, exercise experience, blood sugar test experience and chronic complications experience. Blood glucose and lipids level, body mass index (BMI), dietary control as well as the stages of change for dietary control behavior were compared between the two groups.@*Results@#There was significant difference between the observation group and the control group in the stages of change for dietary control behavior 10 months after intervention ( χ 2=8.92, P <0.05). The compliance score of the observation group was significantly higher than that of the control group in the same period 10 months after the intervention ( t =3.74, P <0.01), the score of the knowledge of diet control in the observation group 10 months after intervention was significantly higher than that in the control group ( t =11.51, P <0.05). The levels of BMI, TG and TC in the observation group were significantly lower than those in the control group at 5 and 10 months after intervention, and the differences were statistically significant ( P <0.05).@*Conclusion@#Experiential health education helps to promote awareness of diabete related knowledge, enhance self management behavior and good diet control habits, and is effective for blood glucose control.

Cohort Profile: the China-Anhui Birth Cohort Study.

The China-Anhui Birth Cohort Study (C-ABCS) was set up to examine the delayed, cumulative and interactive effects of maternal environmental exposures on birth outcomes and children's development. The C-ABCS recruited pregnant women from six major cities of Anhui province, China, between November 2008 and October 2010. A range of data (including demographic, obstetric, occupational, nutritional and psychosocial factors) were collected by both interviews and laboratory tests. In each trimester, women's blood samples were drawn, and pregnancy complications were abstracted from physician's medical records. By the end of 2011, birth outcomes/birth defects were observed/identified by clinicians within 12 months after the delivery of 11,421 singleton live births of six cities and those outcomes among the remaining 2033 live births are still being observed. In addition, 4668 children from Ma'anshan city will be further followed up during the pre-school period till they reach adolescence to obtain the data on familial environmental exposures as well as children's physical, psychological, behavioural and sexual development. The interview data and information on laboratory examinations are available on request from archives in the Anhui Provincial Key Laboratory of Population Health & Aristogenics.

Cross-coupling reactions of two different activated alkenes through tetrabutylammonium fluoride (TBAF) promoted deprotonation/activation strategy: a regioselective construction of quaternary carbon centers.

A novel TBAF-promoted intermolecular crossed-conjugate addition has been developed. For a range of cyclic ß-halo-α,ß-unsaturated carbonyl compounds, the vinylogous enolates generated by deprotonation at the γ-position preferentially reacted with Michael acceptors at the α-position to deliver cross-coupling products in good yields.

[Effects of sludge retention time (SRT) on the characteristics of membrane bioreactor (MBR)].

The effects of sludge retention time (SRT) on extracellular polymeric substances (EPS) content, the characteristics of sludge, the size distribution of sludge particles and the membrane resistance of filtration in the membrane bioreactor were studied. The results indicate that the EPS content is about 90 mg/g in the mixed liquor and 0.8 g/m2 on the membrane surface at 30 d of SRT. And EPS contents increase simultaneously with the extension of SRT, but EPS is hardly accumulated on the membrane surface. In addition, the electric charge on the surface of bacteria change and the proportion of hydrophilic group and hydrophobic group enhance with the rise of the EPS content, then the bacteria are transformed from the unstable (R) from to the stable (S) and the sludge is difficult to settle. The size-distribution profile of particles in the mixed liquor presents a bimodal shape at the long SRT and the peak values shift to the smaller range with SRT extension, at 30 d of SRT the average size of particles is about 14 microm and the two peaks occur at 0.5 microm and 16 microm, respectively. It shows that the content and the size distribution of small particles in the mixed liquor are crucial to the membrane fouling. It is found that it is suitable to control the SRT of membrane bioreactor below 120 times of the shortest generation-time of dominant bacteria (at the highest specific growth rate under the operation temperature) considering the membrane pollution and the characteristics of the mixed liquor.