Prior to implantation, the blastocyst has to hatch out of its zona pellucida to invade the endometrium .In mammals including humans , failure of blastocyst hatching leads to infertility .Blastocyst hatching is believed to be regulated by a variety of autocrine and paracrine molecules such as proteases , cyclooxygenase-2, p38 mitogen-activated protein ki-nase, activin A and Wnt signal pathway .This article reviews the mechanisms of the key molecular regulators involved in mammalian blastocyst hatching and hatching-assisting methods , which can help clarify the mechanism of blastocyst hatching and the treatment of infertility due to failure in blastocyst hatching .

Objective To evaluate the effect of dose-rate and leaf position tolerance on the point dose in step-and-shoot intensity-modulated radiotherapy(IMRT). Methods IMRT plans of 2 prostate cancer patients were selected and recalculated for a water phantom.An ionization chamber was used to measure the dose of some points in the phantom at five nominal dose-rates:100 MU/min,200 MU/min,300 MU/min,400 MU/min and 500 MU/min.It was necessary to adiust the position of the water phantom to locate the ionization chamber in region where the dose gradient was very low in order to minimize the effect of dose gradient on the measured results.When measuring the effect of leaf position tolerance on point dose,the dose-rate was kept constant and the values of tolerance were 1 mm,2 mm,3 mm and 4 mm.This work was conducted on a Varian 23EX equipped with a Millennium 120-leaf multi-leat collimator(MLC).The treatment planning system was Varian Eclipse. Results As the dose-rate increased,the error between the measured dose and the calculated dose also enlarged.The difference between the maximum and the minimum was 1.2%.When MLC control system was working normally,tlle effect of leaf position tolerance on the measured point dose was very little and negligible. Conclusions The dose-rate must be selected suitably to ensure that the delivery can be finished in a short time with the radiobiological effect taking into account.It should be noted that the error between the measured dose and the calculated dose increases with the trend of inereasing more rapidly at higher dose rates.The value of leaf position tolerance should not be set too large,in order to minimize the difference between the measured dose and the planned dose in the region of steep gradient and find as early as possible when the multi-leaf collimator control system performs improperly.

ObjectiveTo evaluate setup errors of image guided radiation therapy (IGRT) for body tumors immbilized with vacuum cushions and localized with final isocenter marked method using kilovoltage cone beam CT (KVCBCT).MethodsA retrospective study has been carried out for 223 patients from March 2009 to April 2011.All patients were immobilized with vacuum cushions and localized with final isocenter marked method in Philips PQS CT or Philips Brilliance CT Big Bore scanner,which were equipped with LAP movable laser systems. The CT images were transferred to a Varian Eclipse workstation for contouring and treatment planning.Before irradiation,a KVCBCT scan was performed and image registration was done on a Varian iX linear accelerator via OBI system.Each set of setup errors in right-left ( RL),superior-inferior (SI),and anterior-posterior (AP) directions were gathered.An independent-samples t-test statistical analysis was conducted with the 758 sets of data using SPSS 16.0.Results The statistical analysis showed that setup errors from the 758 datasets were depicted a Gaussian distribution.The system errors ± random errors in RL,SI and AP were ( -0.5 ±2.8) mm,(0.0±3.0) mm and (0.4±3.4)mm,respectively.Referring to the formula for planning target volume margin calculation,M =2.5Σ + 0.7δ,the margins were calculated as 3.2,2.1 and 3.4 mm,respectively.ConclusionsThe margins derived from this retrospective study have confirmed the premise that the treatment plans were executed in patients with high reliability,thereby created a high sense of confidence for the clinicians.

Objective To compare the planning systems of the simplified manual intensity modulated (SMIM) irradiation and standard tangential (ST) irradiation,in order to explore the application of SMIM technique in clinic.Methods In 64 cases of breast cancers after breast conserving surgery,each underwent both SMIM and ST planning systems.SMIM planning was designed by copying additional fields for shielding the high dose areas from internal or lateral tangential field.The high dose areas were reduced by adjusting the size of the additional field and open tangential field.To optimize the SMIM planning,3 high dose areas (＞ 103% ,＞ 105% and ＞ 107%) were shielded and 3 protocols carried out.The wedges were also optimized in ST plan.The target coverage and dose homogeneity and dose of organ at risk were compared between SMIM and ST planning systems.Results When the dose was normalized to cover the volume of 95% CTV,85% of the shielded areas in optimal SMIM planning were that of ＞ 103% high dose area,and 94% of target area was covered.The study on the volume of breast CTV showed that,in the large breast group,SMIM could not only significantly reduce the high dose areas,and the maximum dose as well as the dose of organ at risk,but also enhance the dose homogeneity index.However,no such effect was not significant in the small breast group.Conclusions The simplified manual intensity modulated technique can improve target dose homogeneity in the large breast cases instead of the standard tangential technique.

Objective To investigate the correction of manual monitor unit calculation for asymmetric fields using the Varian enhanced dynamic wedge.Methods Monitor unit (MU) was calculated when the field sizes ranged from 6 cm × 6 cm to 20 cm × 20 cm at a depth of 5 cm using Varian Eclipse and both 6 MV and 10 MV X-rays data from Varian Clinac 23EX for all seven available EDW angles,including 10°15°,20°,25°,30°,45°and 60° The field size was kept fixed,and the distance between geometry center of field and isocenter was increased in increments of 1 cm,ranging from -9 cm to 4 cm.When the field size was the same,the correction factor was defined as the ratio of MU calculated for asymmetric field to monitor unit calculated for symmetric field.To ensure the correction factors obtained above could be used in routine manual calculation for EDW fields,measurements were made at a depth of 5 cm for 30°and 45°EDW with field size of 10 cm × 10 cm using 6 MV X-rays.Results The correction factor was independent of field dimensions,so the average value was adopted to make practical calculation.Without correction,the maximum error was 18% for 30°,and 30% for 45.After the results of monitor unit calculation were corrected,the largest error was - 1.8% and - 1.7% for 30° and 45°EDW,respectively.The magnitude of errors was within the clinical tolerance limits.Conclusions For asymmetric EDW fields,there is very large difference between the prescribed dose by manual calculation using EDW factors measured for symmetric fields and that delivered during treatment in order to obtain correct dose to reference point.The errors are decreased to be acceptable after correction.The method of correction is simple and independent of machine specific beam parameters.

Objective To investigate the protective effect and the possible mechanism of Wenshen Shengjing Decoction (WSSJD)(including Cornu Cervi Nippon Parvum , Panax ginseng, Cynomorium songaricum, Cistanche deserticola,Radix Astragali, Epimedium brevicornum, Angelica sinensis.) on cyclophosphamide induced testicular oxidative damage in mice . Methods Eight-week-old male Kunming mice were assigned .Mice in normal control group received intraperitoneally nor-mal saline, and mice in Western medicine group ,WSSJD group and model group were injected intraperitoneally with cyclo-phosphamide [80 mg/(kg? d) ]for five days.Then mice in Western medicine group and WSSJD group were gavaged with clomifene citrate or WSSJD for 30 days consecutively .The epididymal sperm count and sperm viability were recorded , and the structure of seminiferous epithelium was observed .The content of malondialdehyde (MDA) and glutathione (GSH), and activities of glutathione peroxidase ( GSH-Px) and catalase ( CAT) in testicular tissue were detected .Immunohisto-chemical technique was used to detect the expression of survivin in spermatogenic cells .The apoptosis of spermatogenic cells in the testes was detected by TUNEL assay .Results Compared with model and Western medicine groups ,the epidid-ymal sperm count and sperm viability rate , the development of seminiferous epithelium , and the activities of GSH-Px and CAT significantly increased , while the MDA content significantly decreased in WSSJD group .The expression of survivin in spermatogenic cells was significantly improved .The apoptotic indexes of seminiferous tubules and spermatogenic cells significantly decreased in WSSJD group .Conclusion These results suggest that WSSJD can significantly improve the impaired reproductive function induced by cyclophospamide in mice by enhancing the antioxidative capability in testes and reducing the apoptosis of spermatogenic cells .

Objective To evaluate the setup errors of image guided radiation therapy (IGRT) for head-and-neck cancer using kilovoltage cone beam CT( kV CBCT).Methods 256 patients with head-and-neck cancer were treated with intensity modulated radiation therapy (IMRT) from March 2009 to October 2011.All patients were immobilized with head-and-neck mask and localized with final isocenter marking method using the Philips PQS CT or Philips Brilliance CT Big Bore scanners,which were equipped with LAP movable laser systems.The CT images were transferred to a Varian Eclipse V8.6 workstation for contouring and planning.A kV cone-beam CT scans was acquired,and registered before the treatment for every patient on a Varian iX linear accelerator via OBI system.The setup errors in the right-left ( RL),superior-inferior (SI),and anterior-posterior (AP) directions were recorded.Results The setup errors for the 473 datasets followed a Gaussian distribution.The systematic errors ± random errors in the RL,SI and AP were(-0.6 ± 1.3 ),(0.5 ± 1.6) and (0.9 ± 1.7 ) mm,respectively.The planning target volume (PTV) margins were calculated respectively as 2.4,2.4 and 3.4 mm according to the formula of M =2.5∑ +0.7δ The margins of 288 sets of data using the Big Bore CT scanner were calculated as 2.0,2.1 and 1.7 mm,respectively.Conclusions The setup errors using final isocenter marking method are smaller than those using reference point marking method.The result derived from this retrospective study could be used to set the margin between CTV and PTV.

Objective:To understand the oral health status of urban and rural residents in China,the Fourth National Oral Health Epidemiological Survey (FNOHES) was conducted in 2015.Materials and methods:Based on the principles of multi-stage,stratified,equal capacity,and random sampling,the subjects included five groups of residents aged 3-5,12-15,35-44,55-64,and 65-74 years in all 31 provinces,municipalities,and autonomous regions except Hong Kong,Macao,and Taiwan.The total sample size was 172,425.The survey covered two areas,namely oral health status and knowledge,attitude and oral health behavior.Results:Residents in China had serious caries and poor periodontal condition.The prevalence of caries was above 50％ in all age groups,subjects without periodontal disease accounted for ＜50％,and fewer than 50％ of subjects brushed their teeth twice a day.Based on the results of the FNOHES,the following suggestions were proposed for improving the oral health in China in the future:to establish and improve the comprehensive prevention and control system for oral diseases,implement a comprehensive prevention and control strategy for priority groups,strengthen the oral health education for all people to improve oral health literacy,enhance dynamic monitoring to scientifically evaluate oral health status,and coordinate multi-party resources to establish and improve the oral health service security system.Conclusion:The oral health status of Chinese residents and their oral health behavior habits need to be improved.With the support of the administrative departments of the government and unremitting efforts of the oral health staff,all sectors of society must be coordinated to strengthen oral health education for the whole population.Furthermore,comprehensive prevention and control measures must be implemented for priority groups.

Objective To study the effect of dopamine D1 receptor antagonist SCH23390 on the behavior of parkinsonian (PD) rats and on electrophysiological characteristics of the entopeduncular nucleus (EP).Methods Intracranial injection of 6-OHDA was conducted in 23 adult male Wistar rats to create PD animal models (experimental group) while the same amount of normal saline was injected in another 19 rats as a control group.(1) After intraperitoneal injection of SCH23390 at various concentrations of 0.010,0.015,0.020,0.025 and 0.030 mg/kg,the step frequency and the discontinuous moving frequency tests were carried out to determine the optimal concentration and time of intervention at 6 time points (10 main before,and 5～15,20～30,30～40,40～50 and 68～78 min after intervention) when all the rats were put on a treadmill at a speed of 8 r/min.(2) After recording electrodes were implanted into the EP in the rats,the signals of spikes in the EP in still and movement conditions were recorded simultaneously using the 16-Channel OmniPlex Neural Data Acquisition System.The spike signals collected were imported into Offiine Sorter to do cluster-sorting analysis and then into NeuroExplorer to analyze alterations in the firing pattern and firing rate of each type of neuron.(3) Frozen sections of the brain samples harvested by perfusion from the rats in the 2 groups were subjected to Nissl's staining and histological assay.Results (1) The behavioral tests showed that intraperitoneal injection of SCH23390 at 0.020 mg/kg at time points of 20～30 min and 30～40 min was optimal.The step frequency for the experimental group (24.47±1.35 step/min) was significantly decreased compared with that for the control group (30.77±2.06 step/min) (t=7.392,P=0.000).(2) After intervention by SCH23390,in movement and still conditions,the firing rate and variation coefficient of EP neurons were significantly higher in the experimental group than in the control group (P＜0.05).(3) The Nissl's staining showed a small number of lightly stained neurons were sparsely disposed in the injured cerebral substantia nigra and the histological assay found altogether 14 rats from which correct EP sites were collected.Conclusions This study demonstrated a negative regulating effect of dopamine D1 receptor antagonist SCH23390 on the behavior of PD rats,which may be exerted by changing the electrophysiological activity of EP.

Objective:To conduct a comparative analysis of the radiation damage to zebrafish embryos and the associated biological mechanism after ultra-high dose rate (FLASH) and conventional dose rate irradiation.Methods:Zebrafish embryos at 4 h post-fertilization were exposed to conventional and FLASH irradiation (9 MeV electron beam). The mortality and hatchability of zebrafish after radiation exposure were recorded. Larvae at 96 h post-irradiation underwent morphological scoring, testing of reactive oxygen species (ROS) levels, and analysis of changes in oxidative stress indicators.Results:Electron beam irradiation at doses of 2-12 Gy exerted subtle effects on the mortality and hatchability of zebrafish embryos. However, single high-dose irradiation (≥ 6 Gy) could lead to developmental malformation of larvae, with conventional irradiation showing the most significant effects ( t = 0.87-9.75, P < 0.05). In contrast, after FLASH irradiation (≥ 6 Gy), the ROS levels in zebrafish and its oxidative stress indicators including superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were significantly reduced ( t = 0.42-15.19, P < 0.05). There was no statistically significant difference in ROS levels in incubating solutions after conventional and FLASH irradiation ( P > 0.05). Conclusions:Compared to conventional irradiation, FLASH irradiation can reduce radiation damage to zebrafish embryos, and this is in a dose-dependent manner. The two irradiation modes lead to different oxidative stress levels in zebrafish, which might be a significant factor in the reduction of radiation damage with FLASH irradiation.