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Objective:To investigate the dosimetry effect of rotational errors of multi-channel cylinder vaginal applicator of intravaginal irradiation after surgery of endometrial cancer.Methods:A total of 18 patients who underwent surgery of endometrial cancer at Peking Union Medical College Hospital from June to December 2022 were selected.The plans of patients who adopted the treatment of multi-channel cylinder applicator of vagina were retrospectively analyzed,which maintained the same retained mode with clinical plan.The applicator was rotated clockwise by 22.5? and 45.0?,respectively,simulating the rotational errors that occurred in placing the applicator among clinical inter-fractions.And then,the changes of dosimetry of target area and organs at risk(OAR)under two kinds of rotation amplitudes were further analyzed.Results:When the applicator was rotated as 22.5?,the minimum doses to 90%volumes of CTV by 2.03%than that of clinical plan,which was significantly different(t=5.86,P<0.05),and the maximal doses to 2cc of OARs of bladder and rectum respectively increased 2.35%and 2.71%,and the differences of them were statistically significant(t=-3.49,-2.40,P<0.05),respectively.When the applicator was rotated as 45?,the D90 of the target area decreased by 5.75%than that of clinical plan,which was statistically significant(t=14.07,P<0.05).The D2cc values of the bladder and rectum increased respectively by 6.50%and 9.49%than that of clinical plan,which were statistically significant(t=-7.72,-6.9,P<0.05).The differences of the exposed doses of sigmoid colon and small intestine after the applicator was rotated by 22.5? and 45.0? between the plan and original plan were respectively less,which were not statistical significance.Conclusion:The multi-channel cylinder applicator can provide individualized dose distribution in intravaginal irradiation.However,attention should be paid to the placement of the applicator when patients undergo inter-fractional treatment,in order to avoid deviations in the angular alignment from the original plan.This can impact the dosages of the target area and OARs.
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Surfactant reduces the surface tension of liquids, resulting in improved emulsion stability, and there is great interest in pesticide additives. Ethoxylate is often used as a pesticide emulsifier. However, the degree of ethoxylation and the existence of dioxane byproducts can significantly affect the performance of emulsifiers. Here, a series of polyoxyethylene tallow amines with the addition of different numbers of ethylene oxide (EO) were synthesized and characterized. Their physical and chemical performances were measured. The ability of POEA as a surfactant to reduce water surface tension and the surface adsorption of molecules were assessed based on the static and dynamic surface tensions. The results show that the surfactant molecules preferentially form a saturated adsorption layer in solution, and the mixed-diffusion-kinetics mechanism dominates the adsorption process. With the increase of the EO addition number, the emulsifying property of POEA increases, while the wetting property gradually decreases and the contact angle increases. These results can provide a basis for the selection of pesticide additives. At the same time, the mechanism of removing dioxane by ethoxylate is described, and a simple and low-consumption method is put forward to reduce the dioxane content. It provides a new idea for the removal of dioxane.
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Objective:To explore the feasibility of synthetic diamond detector in use for Flash radiation dosimetry by designing a diamond dosimeter and conducting a series of dosimetric characteristic tests.Methods:A diamond detector system prototype with real-time current output was developed using a CIVIDEC? B1HV diamond sensor and designing a large dynamic range current measurement circuit based on the pre-integration method. The dose (dose-rate) response linearity was tested under irradiation from both electron beam and X ray ultra-high dose rate. Dose (dose-rate) calibration was performed against a medical accelerator to gain the charge-dose transfer coefficient.Results:Good linear correlation ( R2 = 0.99) between detector output charge and reference dose per pulse was shown under electron beam irradiation of 0.08-0.50 Gy/pulse. Good linearity ( R2 = 0.99) is also shown under irradiation from electron beam with ultra-high dose rate (400 Gy/s) and conventional dose rate (0.5 Gy/s). Strictly linear correlation ( R2 = 1) was shown between detector output integrated charge and reference dose under X ray irradiation at ultra-high average dose rate (75.5 Gy/s) and conventional average dose rate (0.5 Gy/s). The charge-dose and current-dose rate conversion factors for practical use were 0.751 7 μC/Gy and 0.753 5 μA·Gy·s -1, respectively. Conclusions:Considerable linearity of the diamond detector dose responses were shown under irradiation both from electron beam and X-ray beam, which could provide a relatively rapid and accurate dosimetry for Flash preclinical experiments. Furthermore, diamond detectors have great potential in the quality assurance for Flash radiotherapy.
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Objective:To explore the radiation dose of brachytherapy plan for cervical cancer patients under different image-guided method and the time efficiency characteristics of each part of the clinical workflow, so as to provide reference for the overall arrangement of clinical brachytherapy.Methods:The workflow of 223 patients with brachytherapy was retrospectively analyzed. The whole workflow was divided into 5 parts: applicator placement, image acquisition, delineation of target and organs at risk, plan design and review, and treatment implementation. The image-guided brachytherapy was divided into X-ray guided 2D treatment groups, and computed tomography(CT)and magnetic resonance imaging (MRI) guided 3D treatment groups. The radiation dose and the time spent in each part of the three image-guided brachytherapy workflow were calculated. The radiation dose was evaluated using total reference air kerma (TRAK). The results were analyzed using the nonparametric test of SPSS 20 software.Results:TRAK 4.2(4.4, 3.9) cGy was significantly higher in X-ray guided 2D treatment group than in the CT guided 3D treatment group [3.5(3.9, 2.7) cGy, H =90.73, P < 0.01] and the MRI guided 3D treatment group[2.7(2.9, 2.4) cGy, H =90.73, P < 0.01]. The total workflow time of the X-Ray film guidance group was the shortest [55.0(67.0, 50.0) min], followed by the CT guidance group [80.0(91.0, 72.0) min], and the total workflow time of the MRI image guidance group was the longest [119.0(143.0, 105.5) min, H =106.39, P <0.01]. The image acquisition time of the MRI-guided group was significantly higher than that of the X-ray film guidance group and the CT-guided group ( H =44.80, P<0.01). The time of target delineation in the MRI-guided group was significantly longer than that in the CT-guided group ( Z=-5.10, P<0.01). The MRI-guided group took the longest time for planning, followed by the CT-guided group, and the X-ray guided group took the shortest time ( H =57.93, P<0.01). Conclusions:The 2D brachytherapy mode guided by X-ray film had the shortest process time but higher TRAK, while the 3D brachytherapy mode guided by MR had the longest process time, and the planned TRAK result were comparable to those guided by CT. When multiple patients are treated with brachytherapy at the same time, the work efficiency can be improved by interspersing different phases and the waiting time can be avoided.
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Objective:To formulate clinical commissioning procedures, items, and testing method for Flexitron afterloader hardware and software and establish relevant quality control procedures in order to meet national standards and clinical requirements.Methods:Clinical commissioning included hardware, treatment planning system (TPS), and end-to-end (ETE) full-process testing. The radioactive source positioning accuracy was measured using a source position check ruler. The accuracy and linearity of dwell time were evaluated using three method: stopwatch timing, ion chamber measurement, and video analysis. The accuracy of source position simulator, connecting tubes, source position check ruler, and other measuring tools was tested using a high-precision ruler. Films were used for calibration of marker lines and applicators. The electrometer and well chamber were used to calibrate the radioactive source activity. The display and reconstruction accuracies of the TPS were evaluated using physical image data. ETE testing was conducted using a custom-made phantom for scanning, planning, and dose measurement.Results:The accuracy testing result of the commissioning items were within acceptable limits. The deviation in source activity measurements was 0.21%, and the ETE point dose measurement deviation was 2.32%, both of which met the clinical requirements. However, there was a 2 mm difference between the nominal and measured values of the magnetic resonance marker line in the accuracy testing items. Therefore, adjustments were required when using marker line for catheter reconstruction based on magnetic resonance images.Conclusions:By summarizing the clinical commissioning experience of the Flexitron afterloader, this study has developed quality control method and baseline levels of result of afterloader and TPS items, which provides a reference for the commissioning before clinical use.
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Brachytherapy (BT) provides the opportunity to deliver highly potent radiation doses to the tumor, while more effectively sparing the surrounding organs at risk (OAR) due to the proximity of radiation sources to the tumor target and rapid fall-off of the source dose profile. As an important part of radiotherapy for cervical cancer, BT plays an irreplaceable role. The BT process is complex and can be divided into a series of steps. Long time waiting for patients in the state of implantation of the applicator may cause changes in the position of the applicator relative to the tumor and the movement of the OAR. In recent years, artificial intelligence (AI) has made great progress in the medical field. Machine learning and neural network have been widely applied in all aspects of BT, such as implantation of the applicator, image acquisition, segmentation of target area and OAR, reconstruction of the applicator, plan optimization, and treatment delivery, etc. In addition, BT significantly reduces the overall time, improves the homogeneity of operation, and enhances the accuracy of treatment. In this article, the application, development prospects, and challenges of AI in the BT of cervical cancer in recent years were reviewed, aiming to provide novel ideas for the application of AI in BT.
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Frequent transfer of rural labor to cities in developing countries significantly impacts agricultural production. However, whether off-farm employment can promote chemical fertilizer (CF) reduction is still controversial. This study incorporates business scale (BS) and fragmentation degree of arable land (FDAL) into the theoretical analysis framework, shedding light on regulating effects of arable land resource endowment in the process of off-farm employment which influences CF application under different BS and FDAL scenarios. It also empirically tests the theoretical framework by employing the survey data of 318 rice farmers in Jilin Province. The results indicate that: (1) off-farm employment, in general, promotes the adoption behavior of machinery by farmers, and mechanical tillage can significantly reduce the intensity of CF application. (2) If farmers have large BS and non-dispersed farmland parcels, contiguous cultivation will meet the scale threshold for mechanical farming and obtain economies of scale to reduce the intensity of CF application. (3) If farmers have small BS and dispersed farmland parcels, the scale threshold of mechanical farming cannot be met. In order to stabilize agricultural production, farmers will increase the intensity of CF application. According to the empirical results, we put forward some suggestions.
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Engrais , Oryza , Fermes , Agriculture/méthodes , Agriculteurs , Chine , EmploiRÉSUMÉ
Objective:To investigate the influence of left atrial size on the ablation efficacy, cardiac morphology and function after valve replacement combined with X-type radiofrequency ablation on posterior wall of left atrium.Methods:From January 2015 to December 2019, 416 patients with mitral valve disease complicated with atrial fibrillation were divided into two groups according to the size of left atrium(Anteroposterior diameter 60 mm). Valve replacement combined with " X" radiofrequency ablation on posterior wall of left atrium was performed. The clinical data were analyzed retrospectively.Results:Except for the AF types, gender, length of stay and postoperative complications, other clinical data, operative and perioperative indicators were better in small left atria group(SLA)than in large left atria group(LLA). The differences were statistically significant( P<0.05). Fractional shortening(FS), ejection fraction(EF) in SLA at any time point were higher than that in LLA, P<0.05. The sinus rhythm conversion rates, the change rate of LA anteroposterior diameter in SLA at postoperative time points were higher than that in LLA, P<0.05. There was no significant difference of cardiac troponin(cTn) and myoglobin(MYO) between the two groups in 6 months after operation, P>0.05. The B-type natriuretic peptide(BNP), cTn, MYO in the other time points were lower than that in LLA, P<0.05. Conclusion:Larger left atrium reduces the rate of sinus rhythm conversion and maintenance in patients undergoing valve replacement combined with fibrillation ablation. There were worse ventricular remodeling and cardiac function recovery. Preoperative evaluation of left atrial size is helpful for prognosis.
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Background: Patients experience moderate-high intensity postoperative pain after cesarean section (CS). The aim of this study was to investigate the optimal concentrations of ropivacaine and sufentanil for use in controlling pain after CS. Methods: One hundred and seventy-four women undergoing elective CS were randomly allocated to four groups. Epidural analgesia was administered with 0.1% ropivacaine in the R1 group, 0.15% ropivacaine in the R2 group, a combination of 0.1% ropivacaine and 0.5 µg/ml of sufentanil in the R1S group, and a combination of 0.15% ropivacaine and 0.5 µg/ml of sufentanil in the R2S group (at a basal rate of 4 ml/h, bolus dose of 4 ml/20 min as needed). Pain scores (numerical rating scale [NRS]: 0-10 cm) at rest (NRS-R), during movement (NRS-M), and when massaging the uterus (NRS-U) were documented at 6 and 24 h. We also recorded patient satisfaction scores, time to first flatus, motor deficits, and adverse drug reactions. Results: NRS (NRS-R, NRS-M, NRS-U) scores in the R2S group (2 [1-3], 4 [3-5], 6 [5-6], respectively) were lower than in the R1 group (3 [3-4], 5 [4-6], 7 [6-8], respectively) (p < 0.001, p < 0.05, p < 0.01, respectively) at 6 h; and patient satisfaction (9 [8-10]) was improved compared to the R1 group (8 [6-8]) (p < 0.01). The time to first flatus (18.7 ± 11.8 h) was reduced relative to the R1 group (25.9 ± 12.0 h) (p < 0.05). The time to first ambulation was not delayed (p > 0.05). However, the incidence of pruritus (4 [9.3%]) was increased compared to the R2 group (0 [0]) (p < 0.05) at 6 h, and the incidence of numbness (23 [53.5%], 23 [53.5%]) was increased compared to the R1 group (10 [23.3%], 10 [23.3%]) (all p < 0.01) at both 6 and 24 h. Conclusions: Although we observed a higher incidence of pruritus and numbness, co-administration of 0.15% ropivacaine and 0.5 µg/ml of sufentanil administered epidurally optimized pain relief after CS, with treated subjects exhibiting lower NRS scores, shorter time to first flatus, and higher patient-satisfaction scores.
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Objective:To compare the calculation result and analyzes the reasons for their differences so as to provide reference for the revision and improvement of the current national standards on radiation shielding design for the room of brachytherapy.Methods:For the initial activity 10 Ci (1 Ci=3.7×10 10 Bq) of radioactive sources, the shielding schemes of brachytherapy room were designed in accordance with UK Institnte of Physics and Engineering in Medicine(IPEM) Report 75, USA NCRP Report 151 and the national standard GBZ/T 201.3-2014, respectively. The differences in shielding limits, occupancy factors and other relevant factors are compared in detail. Results:The annual exposure time in a typical brachytherpy room was about 330 h. The point-specific concrete thickness were 70, 65, 61, 70, 50 cm as required by NCRP Report 151, 41, 43, 30, 40, 39 cm by IREM regulations and 84, 79, 46, 88, 39 cm by GBZ/T 201.3, respectively. The concerned concrete shielding thickness calculated under the GBZ/T 201.3-2014 was generally thicker, with lesser difference from NCRP Report 151 result, whereas that from the IPEM75 report was thinnest. The equivalent lead shielding thicknesses of the protective doors calculated using the three method are 1.170, 0.854 and 1.040 cm, respectively.Conclusions:The shielding thickness calculated using the calculation method and evaluation index recommended by the current Chinese shielding standards for brachytherapy bunker is similar to that reported in NCRP151, but is conservative. In particular, the evaluation index of instantaneous dose equivalent rate required by the current national standards and the relative conservative value of occupancy factor will significantly increase the shielding thickness required by the main shielding area.
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Objective:To compare the dosimetric parameters and plan complexity between newly-delicated HyperArc (HA) and conventional volumetric-modulated arc therapy (VMAT) in the treatment of brain metastases.Methods:For 26 patients with brain metastases, HA, conventional coplanar (Cop) and non-coplanar (Non-cop) VMAT plans with a prescription dose of 9 Gy 3fx or 6 Gy 5fx were generated. The dosimetric parameters for planning target volume (PTV), RTOG conformity index (RTOG CI), Paddick CI, homogeneity index (HI), gradient index (GI), maximum dose (D max) of brainstem and dose-volume parameters of brain-PTV(V 2Gy-V 26Gy) were statisticaly compared among these three approaches. In addition, the monitor unit (MU) and the plan complexity parameters (including MCSv and AlPO) were statistically compared. Results:To prevent missed targets during treatment, all plans were established with RTOG CI of greater than 1.1. For Paddick CI, HA provided significantly higher conformity (0.89±0.019) than Non-cop (0.87±0.036, P=0.001) and Cop (0.88±0.017, P=0.003) VMAT. For GI, the fastest dose fall-off was noted in HA (3.35±0.64), followed by conventional Non-cop VMAT of (3.70±0.80), and conventional Cop VMAT of (4.90±1.85)(all P<0.05). For the brainstem sparing, HA plan performed better than Non-cop plan[(604.14±531.61) cGy vs.(682.75±558.22) cGy, P<0.05)]. For normal brain tissue sparing, HA approach showed significant reduction than conventional Cop and Non-cop VMAT (both P<0.05). For MU, HA approach (2 872.60 ± 566.93) was significantly lower than those of Non-cop VMAT (3 771.28 ± 1 022.38, P<0.05) and Cop VMAT (4 494.08 ± 1 323.09, P<0.05). In terms of plan complexity, the MCSv of Cop plan was the lowest, indicating that the complexity was the highest ( P<0.05). The AlPO of HA was significantly higher than that of Non-cop VMAT ( P<0.05), suggesting that the complexity of HA plan was lower ( P<0.05). Conclusion:For the treatment of brain metastases, HA provides better conformity, more rapid dose fall-off, better sparing of brainstem and normal brain tissues and less plan complexity compared with conventional VMAT.
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Radiation therapy plays an important role in the adjuvant treatment of patients with early endometrial carcinoma. Vaginal stump is a common site of disease failure for early endometrial carcinoma patients with intermediate-high risk factors for recurrence. Compared with external beam radiotherapy, vaginal brachytherapy (VBT) can achieve comparable local control rate with fewer toxicities. In this article, research progresses upon the application of VBT in patients with early endometrial carcinoma after hysterectomy were investigated from multiple perspectives of the selection of patients, the selection of vaginal applicator, factors influencing dose distribution, image-guided adaptive brachytherapy, the design and implementation of radiotherapy regime. In addition, the application of intensity-modulated VBT and the usage of novel quality assurance equipment were also discussed.
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Objective:To help clinicians simplify the post-processing operations of structures by developing rapid processing software for target area and organs at risk structures based on ESAPI.Methods:SmartStructure script software was developed based on ESAPI, verified and evaluated in clinical work. 10 cases of rectal cancer receiving neoadjuvant radiotherapy, 10 breast cancer treated with postoperative radiotherapy, 10 cervical cancer receiving postoperative radiotherapy, 10 nasopharyngeal carcinoma receiving radical radiotherapy and 10 lung stereotactic body radiotherapy (SBRT) were selected, and different types of tumors had different post-processing operations of structures. In each case, three methods were used for post-processing of structures. In the control group (manual group), normal manual processing was employed. In the experimental group 1(SmaStru-N group), scripts without templates were utilized. In the experimental group 2(SmaStru-P group). scripts combined with templates were adopted. The processing time of the three methods was compared. Clinicians scored the scripting software from multiple aspects and compared the feeling scores of scripting software and manual operation.Results:All three methods can be normally applied in clinical settings. The error rate in the manual group was 7.0%, 3.0% in the SmaStru-N group 0% in the SmaStru-P group, respectively. Compared with the manual method, SmaStru-N shortened the processing time of target area and organs at risk by 60.9% and 93.3% for SmaStru-P. In addition, SmartStructure was superior to manual method in terms of using feeling scores. Clinicians gave lower score for the" applicability" and" simplicity" , and higher score on the" accuracy" and" efficiency" .Conclusions:Compared with conventional manual structure processing method, SmartStructure software can rapidly and accurately process all structures of the target area and organs at risk, and its advantages become more obvious with the increasing number of structures that need to be processed. SmartStructure software can meet clinical requirements, reduce the error rate, elevate processing speed, improve the working efficiency of clinicians, providing basis for the development of adaptive radiotherapy.
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Objective Long non-coding RNA(lncRNA) are aberrantly expressed in breast cancer(BC) and strongly associated with its survival prognosis. The aim of this study is to investigate the expression and effect of IncRNA SPATA31D5P on the invasion and migration capacity of breast cancer cells through adsorption of miR-320a. Methods Totally 30 cases of BC tissues and paraneoplastic tissues were collected, and the expression levels of SPATA31D5P in BC tissues and BC cell lines were detected by Real-time PCR. MDA-MB-231 cells were transfected with SPATA31D5P siRNA interference vector, and cell proliferation, invasion and migration capacity were determined using the cell counting kit-8 assay (CCK-8), 5-ethynyl-2'- deoxyuridine(EdU), Transwell and wound-healing assay respectively. And cell cycle and apoptosis were detected by flow cytometry. Bioinformatics approachs were used to screen for miRNAs that could bind complementarily to SPATA31D5P, and the regulatory effect of SPATA31D5P on miR-320a was detected by Real-time PCR and dual luciferase reporter assay. Results SPATA31D5P levels were significantly higher in BC tissues than in adjacent normal breast tissues, and SPATA31D5P expression was higher in each BC cell line than in normal breast epithelial cells MCF10 A. The level of SPATA31D5P in the interference group was 0. 288±0. 052, which was lower than that of the blank control group 1. 114±0. 096 and negative control (NC) group 1. 079±0. 128 (P< 0. 01). The proliferation activity of MDA- MB-231 cells in the interfered group was significantly reduced and apoptotic rate was obviously increased compared to the NC and control groups (P<0. 01) ;the Gj phase block was observed in the interfered group; the scratch healing rate and number of perforated cells in the interference group were (14. 36 ± 1. 75) % and (26±1.52), which were lower than (52. 25± 1.87)% and ( 67. 33 ± 2. 91 ) of the NC group (PcO.Ol). Dual luciferase experiments confirmed that SPATA31D5P could directly regulate miR-320a expression and luciferase activity. Conclusion SPATA31D5P is highly expressed in BC, interfering with SPATA31D5P expression effectively inhibits the proliferation, migration and invasion of MDA-MB-231 cells, and the mechanism may be related to the targeted regulation of miR-320a.
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Circular RNAs (circRNAs), a novel class of endogenous long non-coding RNAs, have attracted considerable attention due to their closed continuous loop structure and potential clinical value. In this study, we investigated the function of circFASTKD1 in vascular endothelial cells. CircFASTKD1 bound directly to miR-106a and relieved its inhibition of Large Tumor Suppressor Kinases 1 and 2, thereby suppressing the Yes-Associated Protein signaling pathway. Under both normal and hypoxic conditions, the ectopic expression of circFASTKD1 reduced the viability, migration, mobility and tube formation of vascular endothelial cells, whereas the downregulation of circFASTKD1 induced angiogenesis by promoting these processes. Moreover, downregulation of circFASTKD1 in mice improved cardiac function and repair after myocardial infarction. These findings indicate that circFASTKD1 is a potent inhibitor of angiogenesis after myocardial infarction and that silencing circFASTKD1 exerts therapeutic effects during hypoxia by stimulating angiogenesis in vitro and in vivo.
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Régulation négative/génétique , Protéines mitochondriales , Infarctus du myocarde , Néovascularisation pathologique/métabolisme , ARN circulaire , Protéines de liaison à l'ARN , Animaux , Cellules endothéliales de la veine ombilicale humaine , Humains , Mâle , Souris , Souris de lignée C57BL , Protéines mitochondriales/génétique , Protéines mitochondriales/métabolisme , Infarctus du myocarde/génétique , Infarctus du myocarde/métabolisme , Myocarde/métabolisme , Myocarde/anatomopathologie , ARN circulaire/génétique , ARN circulaire/métabolisme , Protéines de liaison à l'ARN/génétique , Protéines de liaison à l'ARN/métabolismeRÉSUMÉ
Objective:To discuss the design details of accelerator room for a novel enclosed O-ring linac Halcyon, and to optimize its protection and layout.Methods:According to the optimization principle of radiation protection and the requirements of national radiation protection standards, and the structural characteristics of Halcyon accelerator, the differences between conventional and this novel accelerator rooms were analyzed by discussing the space layout of the machine room, shielding calculation, electrical facilities, purifying ventilation, temperature and humidity control and other factors.Results:The Halcyon machine had a compact structure, a closed ring frame design and a main beam shielding device, which could greatly reduce the radiation protection pressure while improving the space utilization rate of the machine room. The optimized design layout of the machine room could eliminate hidden dangers, avoid design defects, and prevent adverse consequences caused by design errors.Conclusions:The overall structure of Halcyon accelerator is different from that of conventional accelerators. The design details should be taken into full consideration to ensure the optimization of radiation protection, lay a good foundation for subsequent installation, debugging and operation of the equipment and create a good treatment environment for patients and medical staff.
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To determine whether the newly built lead-acid battery agglomeration area in a town in northern Zhejiang had an impact on the surrounding soil environment after seven years of operation, 76 samples of surface soil around the lead-acid battery concentration area were collected, and the contents of Hg, As, Cu, Zn, Pb, Cd, Ni, and Cr in the soil were determined. Based on the spatial distance of the agglomeration area and 50, 450, and 850 m from the agglomeration area boundary, the soil environmental quality was evaluated using the single factor index, Nemerow comprehensive pollution index, and potential ecological risk index methods. The spatial distribution characteristics of the heavy metals were analyzed using the geostatistical method, and the sources of heavy metals affecting the soil environment were determined by correlation analysis. The results showed that the average contents of Hg, Zn, and Pb in eight heavy metals were higher than their corresponding background values at all spatial scales. The average Cd content in spatial scales other than the agglomeration area was larger than its background value. Only As at 50 m was greater than its background value, whereas the average content of other elements at all spatial distances was lower than their corresponding background values. The spatial variability was high for Hg and Cd but not obvious for other elements. This implies that the influence of regional activities was concentrated mainly on Hg and Cd; the content of both increased with distance from the agglomeration area. Hg and Cd exceeded the risk screening values and were distributed mainly at 450 m and 850 m; 33.33% and 38.89% Hg points and 27.78% and 55.56% Cd points were observed at these distances, respectively. The spatial distribution characteristics of Hg and Cd were consistent with their contents; only Zn and Pb had scattered points that exceeded the risk screening values and generally no obvious spatial distribution characteristics. According to the risk analysis of soil comprehensive pollution caused by the eight heavy metals, Cd was the main source of soil comprehensive pollution risk at a contribution rate of 36.73%, which caused the soil at 850 m to be in a state of alert. Soil ecological risk at a medium level occurred mainly at 450 m and 850 m outside the agglomeration area from Hg and Cd. The contribution rates to the soil quality at these distances were 46.30% and 39.37% for Hg and 38.98% and 49.30% for Cd, respectively. This indicates that regional activities caused Hg and Cd to be the main elements affecting soil quality in the study area. The results of geostatistics and multivariate statistical analysis showed that Hg and Cd were diffused inward from the periphery of the agglomeration area on the axis of the local main wind direction (northeast-southwest), and the main sources of both were coal-burning activities of enterprises in the periphery of the agglomeration area. In summary, the newly build lead-acid battery agglomeration area has not significantly affected the accumulation of heavy metals in the agglomeration area and in the surrounding soil after seven years of operation.
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OBJECTIVE: This study aims to investigate the effect of polo-like kinase 1 (PLK1) inhibition on cisplatin (DDP)-resistant gastric cancer (GC) cells. METHODS: The transcriptional level of PLK1 was measured by quantitative reverse-transcription polymerase chain reaction. Expressions of PLK1 and its downstream mediators as well as autophagy-related protein LC3 I/LC3 II were detected by western blot. An 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 5-ethynyl-2'-deoxyuridine immunofluorescent staining were conducted to evaluate the cell viability and replication activity separately. Flow cytometry was carried out to determine the cell cycle status. The GFP-LC3 vector contributed toward tracking the formation and aggregation of autophagosomes. RESULTS: Drug-resistant SGC-7901/DDP cells showed insignificant changes in all phases after DDP treatment, including DNA replication, cell proliferation, cell cycle, and apoptosis, whereas DDP could significantly improve the autophagy level of SGC-7901/DDP as well as PLK1expression. By downregulating the expression of PLK1, both BI2536 andsi-PLK1 enhanced SGC-7901/DDP sensitivity to DDP, suppressing the proliferation and autophagy as well as improving the apoptosis rate. PLK1 inhibition also resulted in the repression of cell division regulators CDC25C and cyclin B1. CONCLUSION: Together, our experimental results illustrated that the DDP resistance of GC cells might be associated with the aberrant overexpression of PLK1. PLK1 inhibition, including si-PLK1 and BI2536 treatment, could restore the chemosensitivity of drug-resistant SGC-7901/DDP cells and enhance the efficacy of DDP, revealing the potential value of PLK1 inhibition in GC chemotherapy.
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Antinéoplasiques/pharmacologie , Protéines du cycle cellulaire/antagonistes et inhibiteurs , Cisplatine/pharmacologie , Inhibiteurs de protéines kinases/pharmacologie , Protein-Serine-Threonine Kinases/antagonistes et inhibiteurs , Protéines proto-oncogènes/antagonistes et inhibiteurs , Ptéridines/pharmacologie , Tumeurs de l'estomac/traitement médicamenteux , Apoptose/effets des médicaments et des substances chimiques , Autophagie/effets des médicaments et des substances chimiques , Protéines du cycle cellulaire/génétique , Protéines du cycle cellulaire/métabolisme , Lignée cellulaire tumorale , Prolifération cellulaire/effets des médicaments et des substances chimiques , Régulation de l'expression des gènes codant pour des enzymes , Régulation de l'expression des gènes tumoraux , Humains , Protein-Serine-Threonine Kinases/génétique , Protein-Serine-Threonine Kinases/métabolisme , Protéines proto-oncogènes/génétique , Protéines proto-oncogènes/métabolisme , Interférence par ARN , Petit ARN interférent/génétique , Petit ARN interférent/métabolisme , Transduction du signal , Tumeurs de l'estomac/enzymologie , Tumeurs de l'estomac/génétique , Tumeurs de l'estomac/anatomopathologie ,RÉSUMÉ
Objective To analyze the failure and processing methods of helical tomotherapy multileaf collimator (MLC) and summarize relevant maintenance experience,aiming to accurately identify the faulty parts,shorten the downtime and enhance the work time.Methods The failure data of the helical tomotherapy MLC system in the past 48 months were analyzed to identify the common faulty parts,causes and processing methods.Results During the previous 48 months,the MLC failure occurred for 20 times,11 times for air compressor failure,4 times for position verification board failure,twice for leaf driver failure,twice for cushion valve failure and once for the slip of leaf position verification rod.The MLC failure was significantly correlated with the humidity of high-pressure gas.The work time of machine exerted significant effect upon the service time of MLC parts.Conclusions The structure of the helical tomotherapy MLC system is complex.The high-intensity work increases the failure rate.The humidity of high-pressure gas affects the normal operation of the MLC equipment.The faulty parts can be identified,the downtime can be reduced and the work time can be enhanced by summarizing the experience of MLC maintenance.