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Solvents, components of pesticide emulsifiable concentrates (ECs), emit quantities of volatile organic compounds (VOCs) into the atmosphere. In the air, their active involvement in oxidative chemical reactions with oxidants exposed to ultraviolet solar radiation can result in the formation of ozone. The quantitative assessment of VOC emissions from agricultural pesticide applications remains hampered by many factors, especially the volatility coefficient of solvents in pesticides. Therefore, this study identified solvents in 20 widely used pesticide products in China. The volatility coefficients of the solvents were investigated based on a spraying test to evaluate VOC emissions from agricultural pesticide applications and their ozone formation potential (OFP). The results suggest that VOC emissions from agricultural pesticide applications amount to 0.60 Mt in 2017, with insecticides, fungicides, and herbicides contributing 0.39 Mt, 0.12 Mt, and 0.09 Mt of VOCs, respectively. Since VOC emission and maximum incremental reactivity (MIR) led to an OFP value (2.1 g ozone/g product) for insecticides, a primary consideration should be to decrease use of solvents with high volatility coefficients and large MIR values in insecticide products. This work could provide valuable insights regarding response options to reduce VOC emissions and ozone formation.

To develop and validate a 3D-convolutional neural network (3D-CNN) model based on chest CT for differentiating active pulmonary tuberculosis (APTB) from community-acquired pneumonia (CAP).Chest CT images of APTB and CAP patients diagnosed in two imaging centers (n = 432 in center A and n = 61 in center B) were collected retrospectively. The data in center A were divided into training, validation and internal test sets, and the data in center B were used as an external test set. A 3D-CNN was built using Keras deep learning framework. After the training, the 3D-CNN selected the model with the highest accuracy in the validation set as the optimal model, which was applied to the two test sets in centers A and B. In addition, the two test sets were independently diagnosed by two radiologists. The 3D-CNN optimal model was compared with the discrimination, calibration and net benefit of the two radiologists in differentiating APTB from CAP using chest CT images.The accuracy of the 3D-CNN optimal model was 0.989 and 0.934 with the internal and external test set, respectively. The area-under-the-curve values with the 3D-CNN model in the two test sets were statistically higher than that of the two radiologists (all P 0.05), and there was a high calibration degree. The decision curve analysis showed that the 3D-CNN optimal model had significantly higher net benefit for patients than the two radiologists.3D-CNN has high classification performance in differentiating APTB from CAP using chest CT images. The application of 3D-CNN provides a new automatic and rapid diagnosis method for identifying patients with APTB from CAP using chest CT images.

Cutinase can degrade aliphatic and aromatic polyesters, as well as polyethylene terephthalate. Lack of commercially available cutinase calls for development of cost-effective production of efficient cutinase. In this study, eight cutinase genes were cloned from

The analysis, migration, and childhood exposure of methylsiloxanes (MSs) in 32 silicone infant bottle nipples marketed in China were studied. Thirty types of MSs in two families, which included 11 linear MSs (LMSs, L4-L14) and 19 cyclic MSs (CMSs, D4-D22), were identified using gas chromatography-mass spectrometry (GC-MS) associated with standards, retention index, and carbon number rule. In 32 nipples, MSs with molecular weight1000 Da and CMSs were predominant. Considering the actual daily use of bottle nipples, the migration tests of MSs from nipples to artificial saliva and reconstituted powdered formula were performed. In particular, the orthogonal test design-QuEChERS-GC/MS was employed to detect MSs in formula. The median migration level of ΣMSs (MW1000 Da) in formula was 950.9 ng/mL, which was much higher than that in artificial saliva (98.1 ng/mL). If formula is fed to children aged 3-36 months using bottle nipples according to product instructions, the daily oral exposure to ΣMSs (MW1000) for children ranged from 52 to 146 μg/kg bw-day, which were two to five orders of magnitude higher than those of other exposure pathways. In sum, oral intake (especially through formula) may be the predominant pathway of exposure of MSs in children. This research enhances our understanding of the oral exposure risks of MSs and provides useful information that could aid the development of risk management strategies.

PURPOSE The purpose of this study was to investigate the correlation between computed tomography imaging characteristics in lung adenocarcinoma and epidermal growth factor receptor (EGFR) mutations. METHODS A total of 124 patients with lung adenocarcinoma and known EGFR mutation status were collected in this retrospective study. Computed tomography quantitative parameters of each tumor, including total volume, total surface, surface-to-volume ratio (SVR), average diameter, maximum diameter, and average density, were determined using computer-aided detection software. The correlation between the EGFR mutation status and imaging characteristics was assessed. The predictive value of these imaging characteristics for EGFR mutation was calculated using the area under the receiver operating characteristic curve. RESULT Fifty-eight of 124 patients showed EGFR mutations. Patients who are female (P < 0.001) and nonsmokers (P < 0.001) and those with serum carcinoembryonic antigen (CEA) level of ≥5 (P = 0.035) were likely to have EGFR mutation. Computed tomography features including air bronchogram (P = 0.035), absence of cavitation (P = 0.010), and absence of pulmonary emphysema (P = 0.002) and quantitative parameters, such as smaller total surface (P = 0.002), smaller total volume (P = 0.001), higher SVR (P = 0.003), and smaller average diameter (P = 0.001), were associated with EGFR mutation. Logistic regression analysis revealed that the most significant independent prognostic factors of EGFR mutation for the model were nonsmoking (P = 0.035), CEA level of ≥5 (P = 0.004), presence of air bronchogram (P = 0.040), absence of cavitation (P = 0.021), and high SVR (P = 0.014). The area under the receiver operating characteristic curve, sensitivity, and specificity of the model for predicting EGFR mutation were 0.827, 75.8%, and 82.8%, respectively. CONCLUSIONS EGFR-mutated adenocarcinoma showed significantly increased CEA level, presence of air bronchogram, absence of cavitation, and higher quantitative parameter SVR than those with wild-type EGFR.

Rationale and Objectives To compare upper abdominal computed tomography (CT) image quality of new model-based iterative reconstruction (MBIR) with low-contrast resolution preference (MBIRNR40), conventional MBIR (MBIRc), and adaptive statistical iterative reconstruction (ASIR) at low dose with ASIR at routine-dose. Materials and Methods Study included phantom and 60 patients who had initial and follow-up CT scans. For patients, the delay phase was acquired at routine-dose (noise index = 10 HU) for the initial scan and low dose (noise index = 20 HU) for the follow-up. The low-dose CT was reconstructed with 40% and 60% ASIR, MBIRc, and MBIRNR40, while routine-dose CT was reconstructed with 40% ASIR. CT value and noise measurements of the subcutaneous fat, back muscle, liver, and spleen parenchyma were compared using one-way ANOVA. Two radiologists used semiquantitative 7-scale (−3 to +3) to rate image quality and artifacts. Results The phantom study revealed superior low-contrast resolution with MBIRNR40. For patient scans, the CT dose index for the low-dose CT was 3.00 ± 1.32 mGy, 75% lower than the 11.90 ± 4.75 mGy for the routine-dose CT. Image noise for the low-dose MBIRNR40 images was significantly lower than the low-dose MBIRc and ASIR images, and routine-dose ASIR images (p Conclusion MBIRNR40 with low-contrast resolution preference provides significantly lower noise and better image quality than MBIRc and ASIR in low-dose abdominal CT; significantly better objective and subjective image quality than the routine-dose ASIR with 75% dose reduction.

To investigate the influence of virtual monochromatic spectral (VMS) CT images at different energy levels on the effectiveness of a motion correction technique (SSF) in dual-energy Spectral coronary CT angiography (CCTA). 29 cases suspected of or diagnosed with coronary artery disease underwent Spectral CCTA using a prospective ECG triggering with 250 ms padding time. SSF was applied to the determined least-motion phase to generate 6 additional sets of VMS images with energy levels from 40 to 100 keV. CT value and standard deviation (SD) in the aortic root and epicardial adipose tissue were measured. Image quality of the RCA, LAD and LCX was evaluated on a per-vessel basis in each patient. Two reviewers evaluated the artery using the score of the segment. The low energy VMS images increased CT value and image noise compared with higher-energy VMS images, except 90 keV and 100 keV. The CNR of 40–70 keV were higher than those of 80–100 keV (P

The volatile methylisiloxanes (VMSs) D4, D5 and D6 have been included in the Candidate List of Substance of Very High Concern (SVHC) by European Chemicals Agency (ECHA) in June 2018. In response to the concerns from the recent SVHC, this study presents three pretreatment methods including purge and trap (P&T), solid-phase microextraction (SPME) and ultrasound-assisted solvent extraction (UASE) combined respectively with gas chromatography-mass spectrometry (GC-MS), for detection of 9 VMSs in food-contact silicone rubber products. Under their optimal operation conditions, three methods were validated. Compared with SPME-GC-MS and UASE-GC-MS, P&T-GC-MS method showed the lower method detection limits (8.40 × 10−4–1.95 × 10−3 mg/kg), the higher recoveries (91.05%–97.48%) and the good %RSD (7.6–11.9%). Considering to be of sensitivity, accuracy, stability, fully-automatic and solvent-free operation, P&T-GC-MS method was finally applied to quantify 9 VMSs in 56 commercial food-contact silicone rubber products. The results showed that 8 VMSs were found and their total contents varied from 17.97 mg/kg to 645.27 mg/kg in the 28 silicone rubber teats, meanwhile, D3, D4, D5 and D6 were detected and their total contents varied from 5.80 mg/kg to 1.45 × 103 mg/kg in the 28 pieces of silicone rubber bakeware.

Endometriosis is one of the most common disorders that causes infertility in women. Iron is overloaded in endometriosis peritoneal fluid (PF), with harmful effects on early embryo development. However, the mechanism by which endometriosis peritoneal fluid affects embryonic development remains unclear. Hence, this study investigated the effect of iron overload on mouse embryos and elucidated the molecular mechanism. Iron overload in endometriosis PF disrupted blastocyst formation, decreased GPX4 expression and induced lipid peroxidation, suggesting that iron overload causes embryotoxicity and induces ferroptosis. Moreover, mitochondrial damage occurs in iron overload-treated embryos, presenting as decreased ATP levels, increased ROS levels and MMP hyperpolarization. The cytotoxicity of iron overload is attenuated by the ferroptosis inhibitor Fer-1. Furthermore, Smart-seq analysis revealed that HMOX1 is upregulated in embryo ferroptosis and that HMOX1 suppresses ferroptosis by maintaining mitochondrial function. This study provides new insight into the mechanism of endometriosis infertility and a potential target for future endometriosis infertility treatment efforts.

Objective: To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose. Methods: 40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg−1 and 20 cases (Group B) with 300 mgI kg−1. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CTrenal-artery/SDrenal-artery) and contrast-to-noise ratio (CNR=(CTrenal-artery-CTerector spine)/SDerector-spine) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test. Results: Contrast medium dose in the 300 mgI kg−1 group was reduced by 50% compared with the 600 mgI kg−1 group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg−1 group), 40 keV (300 mgI kg−1 group) and 45 keV (300 mgI kg−1 group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg−1 group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg−1) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05) Conclusion: Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA. Advances in knowledge: Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.

Objective To study the clinical value of dual-energy spectral CT in the quantitative assessment of microvascular invasion of small hepatocellular carcinoma. Methods This study was approved by our ethics committee. 50 patients with small hepatocellular carcinoma who underwent contrast enhanced spectral CT in arterial phase (AP) and portal venous phase (VP) were enrolled. Tumour CT value and iodine concentration (IC) were measured from spectral CT images. The slope of spectral curve, normalized iodine concentration (NIC, to abdominal aorta) and ratio of IC difference between AP and VP (RIC AP–VP : [RIC AP–VP = (IC AP −IC VP )/IC AP ]) were calculated. Tumours were identified as either with or without microvascular invasion based on pathological results. Measurements were statistically compared using independent samples t test. The receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of tumours microvascular invasion assessment. The 70 keV images were used to simulate the results of conventional CT scans for comparison. Results 56 small hepatocellular carcinomas were detected with 37 lesions (Group A) with microvascular invasion and 19 (Group B) without. There were significant differences in IC, NIC and slope in AP and RIC AP–VP between Group A (2.48 ± 0.70 mg/ml, 0.23 ± 0.05, 3.39 ± 1.01 and 0.28 ± 0.16) and Group B (1.65 ± 0.47 mg/ml, 0.15 ± 0.05, 2.22 ± 0.64 and 0.03 ± 0.24) (all p Conclusion Dual-energy Spectral CT provides additional quantitative parameters than conventional CT to improve the differentiation between small hepatocellular carcinoma with and without microvascular invasion. Clinical Application/Relevance Quantitative iodine concentration measurement in spectral CT may be used to provide a new method to improve the evaluation for small hepatocellular carcinoma microvascular invasion.

To explore the feasibility of reducing radiation dose and improving image quality in CT portal venography (CTPV) using 80 kV and adaptive statistical iterative reconstruction-V(ASIR-V) in slender patients in comparison with conventional protocol using 120 kV and ASIR.Sixty slender patients for enhanced abdominal CT scanning were randomly divided into group A and group B. Group A used the conventional 120 kV tube voltage, 600 mgI/kg contrast dose and reconstructed with the recommended 40% ASIR. Group B used 80 kV tube voltage, 350 mgI/kg contrast dose and reconstructed with ASIR-V from 40% to 100% with 10% interval. The CT values and standard deviation (SD) values of the main portal vein, left branch, and right branch of portal vein, liver, and erector spinae at the same level were measured to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The image quality was subjectively scored by two experienced radiologists blindly using a 5-point criterion. The contrast dose, volumetric CT dose index, and dose length product were recorded in both groups and the effective dose was calculated.There was no significant difference in general data between the two groups (p0.05), the effective dose and contrast dose in group B were reduced by 63.3% (p0.001) and 39.7% (p0.001), respectively compared with group A. With the percentage of ASIR-V increased in group B, the CT values showed no significant difference, while the SD values gradually decreased and SNR values and CNR values increased accordingly. Compared with group A, group B demonstrated similar CT values (p0.05), while the SD values with 80% ASIR-V to 100% ASIR-V were significantly lower than those of 40% ASIR (p0.001), and the SNR values and CNR values with 70% ASIR-V to 100% ASIR-V were significantly higher than those of 40% ASIR (p0.001). The subjective image quality scores by the two radiologists had excellent consistency (kappa value0.75, p0.001), and the final subjective image quality scores and the subjective scores in each of the 5 scoring categories with 60% ASIR-V to 100% ASIR-V were all significantly higher than those of 40% ASIR, and 80% ASIR-V obtained the highest subjective score among different reconstructions.In CTPV, the application of 80 kV and ASIR-V reconstruction in slender patients can significantly reduce radiation dose (by 63.3%) and contrast agent dose (by 39.7%). Compared with the recommended 40% ASIR using 120 kV, ASIR-V with 80% to 100% percentages can further improve image quality and with 80% ASIR-V being the best reconstruction algorithm.CTPV with 80 kV and ASIR-V algorithm in slender patients can significantly reduce radiation dose and contrast agent dose as well as improve image quality, compared with the conventional 120 kV protocol using 40% ASIR.

Objectives To explore the application of adaptive statistical iterative reconstruction-V (ASIR-V) with combination of 80 kV for reducing radiation dose and improving image quality in renal computed tomography angiography (CTA) for slim patients compared with traditional filtered back projection (FBP) reconstruction using 120 kV. Methods Eighty patients for renal CTA were prospectively enrolled and randomly divided into group A and group B. Group A used 120 kV and 600 mgI/kg contrast agent and FBP reconstruction, while group B used 80 kV and 350 mgI/kg contrast agent and both FBP and ASIR-V reconstruction from 10%ASIR-V to 100%ASIR-V with 10%ASIR-V interval. The CT values and SD values of the right renal artery and left renal artery were measured to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The image quality was subjectively scored by two experienced radiologists blindly using a five-point criterion. The contrast agent, volumetric CT dose index (CTDIvol), and dose length product in both groups were recorded and the effective radiation dose was calculated. Results There were no significant difference in patient characteristics between two groups (p > 0.05). The CTDIvol, dose length product and effective radiation dose in group B were 59.0%, 65.0%, and 65.1% lower than those in group A, respectively (all p 0.05) between two groups with different reconstructions. The SD values with 40%ASIR-V to 100%ASIR-V reconstruction in group B was significantly lower(p 0.75, p Conclusion ASIR-V with combination of 80 kV can significantly reduce effective radiation dose (about 65.1%) and contrast agent (about 42.2%) and improve image quality in renal CTA for slim patients compared with traditional FBP reconstruction using 120 kV, and the 70% ASIR-V was the best reconstruction algorithm in 80 kV renal CTA. Advances in Knowledge Using 80 kV with combination of ASIR-V can significantly reduce radiation dose and contrast agent dose as well as improve image quality in renal CTA for thin patients when compared with FBP using 120 kV.

Distance education model has been applied more and more frequently to a variety of vehicle engineering specialties and has brought tremendous technological advances in the distance education for the aspect of vehicle engineering specialty to the corresponding colleges and universities. However, the operating effect of the practice teaching system for the vehicle engineering specialty has not been ideal due to the incompleteness in its own content effect and the different characteristics of its content information processing from the general information processing. To this end, a kind of construction method for the practice teaching system for the vehicle engineering specialty based on the integration of the asynchronous distance education model is put forward in this paper to improve the skills of the students in the vehicle engineering specialty. The experimental results show that this model has provided a new model and concept for the practice teaching and the training of the innovative talents in the vehicle engineering specialty.

Rationale and Objective This study aimed to investigate the clinical value of spectral computed tomography (CT) in the detection of cholesterol gallstones from surrounding bile. Materials and Methods This study was approved by the institutional review board. The unenhanced spectral CT data of 24 patients who had surgically confirmed cholesterol gallstones were analyzed. Lipid concentrations and CT numbers were measured from fat-based material decomposition image and virtual monochromatic image sets (40–140 keV), respectively. The difference in lipid concentration and CT number between cholesterol gallstones and the surrounding bile were statistically analyzed. Receiver operating characteristic analysis was applied to determine the diagnostic accuracy of using lipid concentration to differentiate cholesterol gallstones from bile. Results Cholesterol gallstones were bright on fat-based material decomposition images yielding a 92% detection rate (22 of 24). The lipid concentrations (552.65 ± 262.36 mg/mL), CT number at 40 keV (−31.57 ± 16.88 HU) and 140 keV (24.30 ± 5.85 HU) for the cholesterol gallstones were significantly different from those of bile (−13.94 ± 105.12 mg/mL, 12.99 ± 9.39 HU and 6.19 ± 4.97 HU, respectively). Using 182.59 mg/mL as the threshold value for lipid concentration, one could obtain sensitivity of 95.5% and specificity of 100% with accuracy of 0.994 for differentiating cholesterol gallstones from bile. Conclusions Virtual monochromatic spectral CT images at 40 keV and 140 keV provide significant CT number differences between cholesterol gallstones and the surrounding bile. Spectral CT provides an excellent detection rate for cholesterol gallstones.

OBJECTIVE: To evaluate the ability of a model-based iterative reconstruction (MBIR) for improving image quality in upper abdominal CT with quarter of the normal dose, in comparison with adaptive statistical iterative reconstruction (ASiR) at normal dose. METHODS: 40 upper abdominal patients were randomly divided into two groups: normal-dose group (n = 20) with tube current modulation for noise index (NI) of 10 HU and 40% ASiR reconstruction; low-dose group (n = 20) with NI = 20 HU in the delay phase and MBIR and 40%ASiR. Images in the delay phase were compared. The CT values and standard deviation (SD) values of the liver, spleen, pancreas, kidney, erector spine and fat were measured. Contrast-noise-ratio (CNR = (CT(tissue)-CT( fat))/SD(fat)) of each measured organ were calculated and compared with one-way ANOVA among the three reconstruction groups. The subjective image scores of the three groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test. RESULTS: Dose reduction of 75 % was achieved for the low-dose scan. The subjective scores (95 % confidence intervals) of the three groups (NI 10–40 % ASiR, NI 20–40% ASiR and NI 20-MBIR) were 4.00 ± 0.79 (3.62–4.37), 3.35 ± 0.58 (3.07–3.62) and 3.90 ± 0.64 (3.60–4.19), respectively with no difference between the NI 10–40% ASiR and NI20-MBIR groups and good consistency between reviewers (κ = 0.726). MBIR had statistically lower SD values and higher contrast-to-noise ratio values in the liver, spleen, pancreas, kidney and erector spine than NI 10–40% ASiR and NI 20–40% ASiR (all p < 0.05). CONCLUSION: At 75 % dose reduction, MBIR provides similar image quality compared to 40% ASiR at normal-dose. ADVANCES IN KNOWLEDGE: MBIR provides good image quality at 25 % of the normal dose.

OBJECTIVE: To investigate the application of low radiation and contrast dose spectral CT angiology using rapid kV-switching technique in the head and neck with subtraction method for bone removal. METHODS: This prospective study was approved by the local ethics committee. 64 cases for head and neck CT angiology were randomly divided into Groups A (n = 32) and B (n = 32). Group A underwent unenhanced CT with 100 kVp, 200 mA and contrast-enhanced CT with spectral CT mode with body mass index-dependent low dose protocols. Group B used conventional helical scanning with 120 kVp, auto mA for noise index of 12 HU (Hounsfield unit) for both the unenhanced and contrast-enhanced CT. Subtraction images were formed by subtracting the unenhanced images from enhanced images (with the 65 keV-enhanced spectral CT image in Group A). CT numbers and their standard deviations in aortic arch, carotid arteries, middle cerebral artery and air were measured in the subtraction images. The signal-to-noise ratio and contrast-to-noise ratio for the common and internal carotid arteries and middle cerebral artery were calculated. Image quality in terms of bone removal effect was evaluated by two experienced radiologists independently and blindly using a 4-point system. Radiation dose and total iodine load were recorded. Measurements were statistically compared between the two groups. RESULTS: The two groups had same demographic results. There was no difference in the CT number, signal-to-noise and contrast-to-noise ratio values for carotid arteries and middle cerebral artery in the subtraction images between the two groups (p > 0.05). However, the bone removal effect score [median (min-max)] in Group A [4 (3–4)] was rated better than in Group B [3 (2–4)] (p < 0.001), with excellent agreement between the two observers (κ > 0.80). The radiation dose in Group A (average of 2.64 mSv) was 57% lower than the 6.18 mSv in Group B (p < 0.001). The total iodine intake in Group A was 13.5g, 36% lower than the 21g in Group B. CONCLUSION: Spectral CT imaging with rapid kV-switching in the subtraction angiography in head and neck provides better bone removal with significantly reduced radiation and contrast dose compared with conventional subtraction method. ADVANCES IN KNOWLEDGE: This novel method provides better bone removal with significant radiation and contrast dose reduction compared with the conventional subtraction CT, and maybe used clinically to protect the thyroid gland and ocular lenses from unnecessary high radiation.

The mechanism underlying visceral pain is still largely unclear. Recently, much attention has focused on a potential modulatory role of brain-derived neurotrophic factor (BDNF) in visceral pain. In the present study, we investigated the expression of BDNF in dorsal root ganglia (DRG) primary sensory neurons and its role in a colorectal distention (CRD)-induced model of visceral pain. Results obtained from enzyme-linked immunosorbant assay (ELISA) revealed that BDNF protein was upregulated after CRD. An abdominal withdrawal reflex (AWR) assay confirmed that BDNF played an antinociceptive role in this model. Application of BDNF directly to DRG neurons decreased their hypersensitivity when evoked by CRD. Pretreatment with k252a partially blocked the effect of BDNF. These findings suggest that BDNF might be a novel analgesic agent for the treatment of visceral pain. © 2012 Wiley Periodicals, Inc.