Bis-(3′,5′) cyclic di-guanylate (c-di-GMP) is an almost ubiquitous intracellular second messenger in bacteria.Now it is known to regulate complex physiological processes, including mobility, adhesion, virulence and biofilm formation.The level of c-di-GMP is regulated by diguanylate cyclases (DGCs) containing GGDEF domains and phosphodiesterases (PDEs) containing EAL or HD-GYP domains.Recent studies have demonstrated that HD-GYP domain protein is a novel phosphodiesterase, which is also involved in the regulation of c-di-GMP degradation.This review highlights recent advances in the structure and biochemical functions of HD-GYP domain proteins, which might help to further clarify the mechanism of c-di-GMP signal system.

Objective To investigate the regulatory effects of cyclic diguanylate (c-di-GMP) signaling on CheB and CheR, which were chemotaxis regulatory proteins relating to the motility of Leptospira interrogans.Methods Real-time PCR was used to determine the expression of cheB1, cheB2, cheB3, cheR1 and cheR2 genes at mRNA level during Leptospira interrogans infection.Fragments of these genes were amplified and cloned into the expression vector pET-28a, respectively, to construct the prokaryotic expression system for them.Colony morphologies of Escherichia coli (E.coli) strains that overexpressed the target genes were observed to determine the regulatory effects of c-di-GMP on CheB and CheR.Results The expression of cheB1 gene at mRNA level increased 60 min after infection and reached the peak at 90 min.Compared with the control group, the expression of cheB3 gene at mRNA level were up-regulated, while no significant difference in the expression of cheB2 and cheR genes was observed 60 min after infection.The prokaryotic expression system for the five genes was successfully constructed and the purified proteins were obtained.CheB1, CheB3 and CheR2 improved the motility of E.coli, but that was inhibited by the inhibitor of diguanylate cyclase (DGC) or phosphodiesterase (PDE).Conclusion CheB and CheR regulate the swarming motility of E.coli and are affected by intracellular c-di-GMP.

Objective To develop a rapid and reliable method for determination of 210Po using large-area grid ionization chamber α spectrometry.Methods Samples were digested using a microwave digestion system.After preparation of sample source,the concentration of 210Po in clam was detected by large-area grid ionization chamber (φ 25 cm).209Po tracer was used to obtain the recovery.Results Large-area grid ionization chamber could achieve better counting and α spectrum resolution when the optimized thickness was 250 μg/cm2.By spiking 209Po tracer in clam,the minimum detectable activity was 9.870 × 10 4 Bq and the recovery of 210Po was 98％.Conclusions Compared with the traditional method,the developed method can avoid separation process,using less quantity of sample (0.2-0.5 g dry) and simplify the measurement process.This method may be has broad application prospects.

Objective To investigate the activity concentration of 90St in tea produced in Chinese typical regions,enrich the baseline data for 90Sr level in Chinese tea,and evaluate possible exposure doses to people.Methods Samples were carbonized,ashed,digested and leached,and then extraction chromatography method was used to separate 90Sr and 90y.After preparation of sample source,radioactivity of 90Y was measured using low-level α/β counter.Results Twenty six kinds of tea produced in 16 typical regions from 26 cities of 16 provinces were collected in 2016,and their 90Sr activity concentrations were analyzed using the separation method of di (2-ethylhexyl) phosphate (HDEHP) extraction chromatography.The results revealed that the activity concentrations in 26 kinds of tea samples ranged from 0.28 to 3.78 Bq/kg,and contributed possible exposure doses of 0.44 × 10-2-6.00 × 10-2 μSv to each people.Conclusions These doses were far less than the ICRP annual dose limit of 1 mSv for the public,suggesting less impact on people's health.

Objective To establish an effective and reliable method for analysis of uhratrace uranium in multi-stage atmospheric particles providing the monitoring and evaluation of the content of radioactive uranium in the atmosphere.Methods A large volume six-stage-impactor sampler of atmosphere particles was used to collect aerosol samples,and uhratrace uranium in particles was digested using microwave and measured by inductively coupled plasma mass spectrometry.The filter material,digestion conditions and microwave digestion system had been optimized.Results The background of uranium level on the cellulose filter was the lowest,and the samples were digested by using HNO3-HCI (aqua regia)-H2O2 solution.Reference material SRM2783 was used to validate the accuracy of the method,and the relative error of the 238U was 7％,The detection limit of the method was 2 × 10-4ng/m3.The aerosol actual samples were analyzed using the established method.The mass concentrations of uranium in PM2.5 was in the range of 0.023-0.065 ng/m3.Conclusions The established method was effective and reliable to monitor the concentration level of ultratrace uranium in multi-stage atmospheric particles.

Objective: To investigate the epidemiological characteristics of malaria in Hangzhou City from 2004 to 2021, so as to provide the evidence for formulating the post-elimination control strategy for malaria in Hangzhou City. Methods: The epidemic situation of malaria in Hangzhou City from 2004 to 2021 were collected from the National Information System for Disease Control and Prevention in China, and the temporal, spatial and human distributions of malaria cases and the source of malaria infections were analyzed in Hangzhou City during the pre-elimination stage (2004 to 2009), the elimination stage (2010 to 2015) and the post-elimination stage (2016 to 2021). Results: Totally 602 malaria cases were reported in Hangzhou City from 2004 to 2021,and the annual mean incidence of malaria was 0.22/105, 0.20/105 and 0.18/105 during the pre-elimination, elimination and post-elimination stages, appearing a tendency towards a decline. Men accounted for 63.96%, 85.07% and 93.75% of all malaria cases and there were 67.86%, 82.84% and 80.00% of cases at ages of 18 to 50 years during the pre-elimination, elimination and post-elimination stages, both appearing a tendency towards a decline (χ2trend=56.748, P<0.001; χ2trend=39.971, P<0.001). The predominant occupation of malaria cases shifted from farmers or migrant workers to multiple occupations, and the proportion of commercial servants increased from 4.87% during the pre-elimination stage to 24.38% during the post-elimination stage (χ2trend=73.308, P<0.001). The proportion of Plasmodium vivax malaria cases reduced from 96.43% during the pre-elimination stage to 7.50% during the post-elimination stage, and the proportion of P. falciparum malaria cases increased from 3.57% to 71.25%, while P. ovale, P. malariae and mixed infections were identified since 2010. There was a significant season-specific incidence of P. vivax malaria during the pre-elimination stage, and the period between May and October was an epidemic season; however, there was no season-specific incidence of P. vivax malaria during the elimination and post-elimination stages. The regional distribution of malaria cases presented a tendency towards a shift from suburb and rural areas to urban areas (χ2trend=74.229, P<0.001). No local cases were detected in Hangzhou City since 2010, and 94.22% of malaria cases were overseas imported cases after malaria elimination, including 90.61% from Africa. Conclusions oung and middle-aged men were high-risk populations for malaria in Hangzhou City from 2004 to 2021, and overseas commercial servants gradually became the predominant source of malaria infections, with malaria parasite species tending to be diverse. Improving the management of overseas imported cases and timely identification and treatment of cases are major interventions to consolidate malaria elimination achievements in Hangzhou City.

Objective: To explore the impact role of Mandibular Distraction Osteogenesis technique (MDO) on the health quality of life in children with Pierre-Robin Sequence (PRS). Methods: From January 2017 to August 2017, 44 cases of children with PRS admitted in children′s hospital of Nanjing Medical University were recruited. Glasgow Children′s benefit inventory(GCBI), Chinese version was used to study postoperative qualify of life in four aspects: physiology, emotions, learning, and vitality. Clinical data and the quality of life score were collected from the patients, and comparison analysis was performed. Results: GCBI total score of the 44 cases of PRS treated with MDO surgery was 46, indicating that the overall quality of life was improved; Physical dimension score was 72, which was the highest, showing the most positive changes. GCBI total scores for the children with different types of PRS were type Ⅰ62, type Ⅱ43, type Ⅲ18, respectively. Nonparametric test showed that quality of life in typeⅠpatients was improved compared to typeⅢ. The difference was statistically significant (Z = -3.34, P=0.01). For the comparisons between type Ⅰ and Ⅱ and type Ⅱ and type Ⅲ, there was no statistically significant difference (P>0.05). Conclusions MDO plays a positive role in improving life of quality . Physiological conditions were the aspects that were improved most. The milder the case is, the more the postoperative quality of life is improved.

Objective: To explore the effects of Bmi1 on proliferation of mouse cranial suture mesenchymal cells. Methods: Primary posterior frontal and sagittal suture derived cells were isolated from the 2-5 d old C57BL/6 suckling mice (n=6) of the same brood and cultured. Flow cytometry and multilineage differentiation assay were performed to identify the mesenchymal stem cells (MSCs) characteristics of the 2 kinds of cranial suture-derived cells. The mRNA expression of stem cell related genes, Bmi1, Twist1, Gli1 and Axin2 were detected by real-time quantitative polymerase chain reaction (RT-PCR). Then, the proliferation and downstream protein expression were analyzed after down-regulation of Bmi1 in the sagittal suture derived MSCs by transfecting Bmi1 siRNA. The t test was used to compare the mean between two groups. Statistical significance was set at P<0.05. Results: The mouse cranial suture derived cells were successfully cultured in vitro. These cells expressed typical MSCs markers, CD44, CD90, CD73, except for CD34. These cells had osteogenic, adipogenic and chondrogenic differentiation potency. RT-PCR results showed that the mRNA expressions of Bmi1 (0.006 30±0.000 58 vs 0.002 60±0.000 34, t=5.430, P=0.005 6), Twist1(0.000 31±0.000 04 vs 0.000 15±0.000 02, t=3.343, P=0.028 8), Axin2(0.000 33±0.000 03 vs 0.000 17±0.000 05, t=3.067, P=0.037 4) and Gli1 (0.001 10±0.000 13 vs 0.000 60±0.000 33, t=3.956, P=0.016 7) were significantly decreased in the posterior frontal suture MSCs compared with those in sagittal suture derived cells. Among them, Bmi1 has the largest decline. After down-regulation of Bmi1 in sagittal suture MSCs, the protein expression level of Ink4a was significantly up-regulated compared with the control group, and the cell proliferation ability was significantly decreased. Conclusions Inhibition of Bmi1 expression can up-regulate the expression of Ink4a protein and decrease the proliferation ability of suture MSCs, which may lead to craniosynostosis.

Background and Objectives: Cranial sutures play a critical role in adjustment of skull development and brain growth. Premature fusion of cranial sutures leads to craniosynostosis. The aim of the current study was to culture and characterize human cranial suture mesenchymal cells in vitro. Methods: The residual skull tissues, containing synostosed or contralateral suture from three boys with right coronal suture synostosis, were used to isolate the suture mesenchymal cells. Then, flow cytometry and multilineage differentiation were performed to identify the typical mesenchymal stem cell (MSC) properties. Finally, we used quantitative real-time polymerase chain reaction (RT-PCR) to detect the mRNA expression of osteogenesis and stemness related genes. Results: After 3 to 5 days in culture, the cells migrated from the tissue explants and proliferated parallelly or spirally. These cells expressed typical MSC markers, CD73, CD90, CD105, and could give rises to osteocytes, adipocytes and chondrocytes. RT-PCR showed relatively higher levels of Runx2, osteocalcin and FGF2 in the fused suture MSCs than in the normal cells. However, BMP3, the only protein of BMP family that inhibits osteogenesis, reduced in synostosed suture derived cells. The expression of effector genes remaining cell stemness, including Bmi1, Gli1 and Axin2, decreased in the cells migrated from the affected cranial sutures. Conclusions The MSCs from prematurely occlusive sutures overexpressed osteogenic related genes and down-regulated stemness-related genes, which may further accelerate the osteogenic differentiation and suppress the self-renewal of stem cells leading to craniosynostosis.

Objective:To investigate the safety and efficacy of sirolimus through the change in platelet counts during the sirolimus therapy on Kasaback-Merritt phenomenon(KMP).Methods:Four patients were treated in Nanjing Children Hospital between Jaunary 2017 and June 2019 were enrolled in the study, including two males and two females. Their age was ranged from two days to three months. They all presented with huge mass located in neck or retroperitoneal and thrombocytopenia, hypofibrinogenemia. Their coagulation could not be improved by surgery or palate transfusion or steroids. They were all diagnosed as Kaposiform hemangioendothelioma(KHE) with KMP according to the biopsy, coagulation index and CT. Sirolimus were administered with 0.1 mg -1·kg -1·d -1 or 0.8 mg/m 2, twice daily. Subsequent dose was adjusted to maintain the trough level between 10-15 ng/ml.Steroids were weaned gradually. Blood accounts were measured following the sirolimus administration. Results:All the four patients got improvement in platelet counts. Three patients went through a significant decreasing of palate counts after adding sirolimus for about 1-4 days. Two lesions prompted improvement with smaller size, lighter color and softer texture without complete regression. Two patients had elevated liver enzymes and/or interstitial pneumonia. One recovered while the other died of severe pneumonia with dyspnea. All the palate counts of survived patients remained in normal level in the following one year.Conclusions:Sirolimus is an effective method in treating KMP and stabilizing platelet counts. However, it can not cure hemangioendothelioma.