BACKGROUND: Seed cells with good proliferation and enough amounts are need in reconstructing artificial salivary gland in vitro. However, adult stem cells are difficult to be isolated from normal submandibular gland.OBJECTIVE: To in vitro isolate submandibular gland stem/progenitor cells for cloning culture using animal models of damaged gland tissue.DESIGN, TIME AND SETTING: Cytological in vitro experiment was performed at the Gu.izhou Provincial Key Laboratory of Cell Tissue Engineering, Zunyi Medical College from March 2006 to January 2007.MATERIALS: A total of 10 male Sprague Dawley rats aged 8 weeks were supplied by the Animal Center, Third Military Medical University of Chinese PLA.METHODS: The model of tissue damaged submandibular gland in 10 rats was made by deligation. One week later, the gland tissue was obtained to harvest submandibular gland stem/progenitor cells by enzyme digestion in vitro. Following 10-14 days of primary culture, small round cells were collected, purified and subcultured for monoclonal culture.MAIN OUTCOME MEASURES: Immunocytochemical staining and immunofluorescence staining results were measured in submandibular gland stem/progenitor cells. Growth curve was drawn to analyze the proliferation of submandibular gland stem/progenitor cells in vitro.RESULTS: Cells expressing laminin showed stem cell characteristics. Positive expression of CD29 suggested high-adherent and high-proliferative stem cell properties. Positive expression of keratin-19 indicated epithelium-derived submandibular gland stem/progenitor cells. Growth curve was near to "S" shape, and in vitro culture and proliferation was active.CONCLUSION: Submandibular gland stem/progenitor cells had the characteristics of tissue stem cells. They might be as a kind of seed cells for tissue engineered artificial salivary gland in further research.

Objective:To study the feasibility of using pelvic iterative cone beam CT images for dose calculation of radiation therapy planning, so as to provide support for adaptive radiotherapy.Methods:The CIRS 062 M phantom was scanned by Varian Halcyon v2.0 o-ring accelerator, and the average CT number under different scattering conditions was calculated, and then the ICBCT-ED conversion curve was established. CT images of CIRS 002PRA pelvic IMRT phantom and ICBCT images at different positions were collected. Treatment plan using VMAT technique based on CT image was designed and transplanted into ICBCT image with dose recalculated. The differences of gamma passing rate among target volume, organs at risk and 3-dimensional dose were compared. Based on the actual treatment plan of patients, the differences of 3-dimensional dose gamma passing rate in 10 pelvic patients were analyzed retrospectively.Results:There was a large CT value deviation at central position between the isolated no-scattering condition and the full-scattering condition, and the maximum deviation was 144 HU. The CT values of other positions in full-scattering condition were similar to those of the central position, and the maximum deviation was less than 50 HU. Based on the calculated result of ICBCT images at different positions of the pelvic phantom, the dose deviation of the target volume or organs at risk was less than 1 Gy. Compared with the plan based on CT images, the average 3-dimensional dose gamma passing rate under the criteria of 1% dose difference (DD)/1 mm distance-to-agreement (DTA) and 2% DD/2 mm DTA in plan based on ICBCT images were (88.86 ±1.18)% and (98.38±0.89)%, respectively. The ranges of average 3-dimensional dose gamma passing rate under the criteria of 2% DD/2 mm DTA and 3% DD/3 mm DTA in 10 patients with pelvic tumors were 90.03%-95.43% and 93.58%-97.78%, respectively, and the worst result was only 85.90% and 92.90%, respectively. The main reason of the worst result was the dose difference caused by large variation of bladder contour due to over-filling.Conclusions:Under comprehensive scattering conditions, the ICBCT-ED conversion curve is reconstructed and the treatment plan can be designed by using the ICBCT image of Halcyon v2.0 linear accelerator. The accuracy meets the standards of clinical application, which provides assurance for adaptive radiotherapy in the future.

Objective:To study the distribution and antibiotics resistance of the main pathogens of neonatal purulent meningitis in different regions of China.Methods:A retrospective descriptive clinical epidemiological study was conducted in children with neonatal purulent meningitis which admitted to 18 tertiary hospitals in different regions of China between January 2015 to December 2019. The test results of blood and cerebrospinal fluid, and drug sensitivity test results of the main pathogens were collected. The distributions of pathogenic bacteria in children with neonatal purulent meningitis in preterm and term infants, early and late onset infants, in Zhejiang Province and other regions outside Zhejiang Province, and in Wenzhou region and other regions of Zhejiang Province were analyzed. The chi-square test was used for statistical analysis.Results:A total of 210 neonatal purulent meningitis cases were collected. The common pathogens were Escherichia coli ( E. coli)(41.4%(87/210)) and Streptococcus agalactiae ( S. agalactiae)(27.1%(57/210)). The proportion of Gram-negative bacteria in preterm infants (77.6%(45/58)) with neonatal purulent meningitis was higher than that in term infants (47.4%(72/152)), and the difference was statistically significant ( χ2=15.54, P=0.001). There were no significant differences in the constituent ratios of E. coli (36.5%(31/85) vs 44.8%(56/125)) and S. agalactiae (24.7%(21/85) vs 28.8%(36/125)) between early onset and late onset cases (both P>0.05). The most common pathogen was E. coli in different regions, with 46.7%(64/137) in Zhejiang Province and 31.5%(23/73) in other regions outside Zhejiang Province. In Zhejiang Province, S. agalactiae was detected in 49 out of 137 cases (35.8%), which was significantly higher than other regions outside Zhejiang Province (11.0%(8/73)). The proportions of Klebsiella pneumoniae, and coagulase-negative Staphylococcus in other regions outside Zhejiang Province (17.8%(13/73) and 16.4%(12/73)) were both higher than those in Zhejiang Province (2.9%(4/137) and 5.1%(7/137)). The differences were all statistically significant ( χ2=14.82, 12.26 and 7.43, respectively, all P<0.05). The proportion of Gram-positive bacteria in Wenzhou City (60.8%(31/51)) was higher than that in other regions in Zhejiang Province (38.4%(33/86)), and the difference was statistically significant ( χ2=6.46, P=0.011). E. coli was sensitive to meropenem (0/45), and 74.4%(32/43) of them were resistant to ampicillin. E. coli had different degrees of resistance to other common cephalosporins, among which, cefotaxime had the highest resistance rate of 41.8%(23/55), followed by ceftriaxone (32.4%(23/71)). S. agalactiae was sensitive to penicillin, vancomycin and linezolid. Conclusions:The composition ratios of pathogenic bacteria of neonatal purulent meningitis are different in different regions of China. The most common pathogen is E. coli, which is sensitive to meropenem, while it has different degrees of resistance to other common cephalosporins, especially to cefotaxime.