Objective: To understand the prevalence of HIV testing and related factors among young students who had sex in Guangdong Province, in order to provide evidence for relevant education programs and HIV testing promotion in young students. Methods: From September to December 2022, a convenient sampling method was used to select 48 749 young students from 16 universities and mechanic colleges in 6 cities including Guangzhou, Shantou, Maoming, Huizhou, Dongguan, and Zhongshan in Guangdong Province for online questionnaire survey. A total of 2 971 students who ever had sexual experiences were screened out, and the HIV testing situation and related factors were investigated by using the questionnaire designed by AIDS Prevention and Education Project for College Students of China STD and AIDS Prevention Association.The influencing factors of HIV testing were analyzed using Chi square test and multiple Logistic regression model. Results: Among students who had sexual experiences, 11.92% (354/2 971) were tested for HIV. The results of multivariate Logistic regression analysis showed that among young sexual students, using psychoactive substances during sexual activity in the last 1 year ( OR =7.70), having first sex with the same sex ( OR =3.87), having commercial sex ( OR =2.37), having heard of PEP ( OR =2.20), having a high level of self assessed understanding of HIV testing ( OR =1.73), inconsistent use of condoms ( OR =1.56), being aware of HIV infection ( OR =1.53), being aware of HIV knowledge ( OR =1.51) were more likely to test for HIV, and females ( OR =0.39) were less likely to test for HIV ( P < 0.05). Conclusions The proportion of HIV testing is low among sexually active young students in Guangdong Province. Targeted interventions should be tailored to promote HIV testing coverage.

Objective:To evaluate the effect of novel erythrocyte preservation solution on the quality of erythrocytes in stored blood of type 2 diabetes mellitus (T2DM) rats.Methods:Forty SPF male Sprague-Dawley rats, aged 8 weeks, weighing 180-220 g, were used in this study. Ten rats randomly selected served as conventional erythrocyte preservation solution group (group A). T2DM model was prepared in the remaining 30 rats. Twenty T2DM rats were divided into 2 groups ( n=10 each) using a random number table method: T2DM conventional erythrocyte preservation solution control group (group C) and T2DM novel erythrocyte preservation solution observation group (group Y). Erythrocyte preservation solution was prepared to simulate the preoperative autologous blood donation process, and blood was collected from the tail vein to isolate the red blood cells, and then the corresponding preservation solution was added. Immediately after blood collection (T 0) and at 7, 14 and 21 days of preservation (T 1-3), the morphological structure of erythrocytes was observed with a light microscope, and the concentrations of 2, 3-diphosphoglycerate (2, 3-DPG) and reactive oxygen species (ROS) were also determined by enzyme-linked immunosorbent assay at T 0-T 3 and 28 days of preservation (T 4). PKH26 was used to label the erythrocytes stored in vitro for 28 days, and then the erythrocytes were transfused back into rats. The survival rate of erythrocytes was detected by flow cytometry at 1, 7, 13 and 18 h after retransfusion. Results:The erythrocyte damage was aggravated at different time points of preservation in group C when compared with group A. Compared with group C, the damage to erythrocytes was significantly alleviated at different time points of preservation in group Y. Compared with group A, the concentration of 2, 3-DPG in erythrocytes was significantly decreased at T 0 and T 2-T 4, the concentration of ROS was increased at T 0-T 4, and the survival rate of erythrocytes was decreased at 1, 7 and 18 h after retransfusion in group C ( P<0.05). Compared with group C, the concentration of 2, 3-DPG in erythrocytes was significantly increased at T 0-T 4, the content of ROS was decreased at T 1, T 3 and T 4, and the survival rate of erythrocytes was increased at 1, 7 and 18 h after retransfusion in group Y ( P<0.05). Conclusions:The novel erythrocyte preservation solution can improve the quality of stored erythrocytes and increase the survival rate of erythrocytes in vivo after retransfusion in T2DM rats.

Objective:To explore high-risk sexual behaviors of HIV/AIDS and related factors in young students in Guangzhou.Methods:A cross-sectional survey was conducted in 5 different types of Guangzhou colleges by convenience sampling with minimum number of classes per grade and 600 samples per school from September to November 2021. The R 4.2.2 software was used to consolidate databases. Simultaneously, a logistic regression model and a decision tree algorithm model, stratifying by whether sexual behaviors had occurred before, were constructed. In each layer, the prediction performance of the two models was evaluated through area under receiver operating characteristic and the confusion matrix, and then the model with high prediction performance was retained.Results:A total of 7 346 students were surveyed. The proportion of the respondents reporting sexual experience were 9.08% (667/7 346), in whom 26.24% (175/667) had risky sexual activity in the past year. The decision tree algorithm model performs well in predicting whether high-risk sexual behaviors have occurred in the past year. When the complexity parameter value is 0.018, and nsplit reaches 4, which means there are 5 leaf nodes in the model, the cross error of the tree will be the smallest. The first best grouping variable in the decision tree was whether to use condoms throughout the first sexual behavior. If condoms were used at their sexual debut, but homosexual practices have occurred in the past year, the probability of risky sexual behavior will increase. If homosexual practices have not occurred in the past year, but the age of sexual debut was below 18 years old while the period of HIV education was after high school, the probability of risk sexual behavior will also increase.Conclusions:AIDS-related risky behaviors of young students still deserved attention. The experience of sexual debut and whether AIDS-related health education has been received before the sexual debut were significant predictors for the occurrence of high-risk sexual behavior. The decision tree algorithm model has particular applicability for predicting and screening potential risk populations.

AIM: To observe the effect of RBC preservation solution with sodium pyruvate on the morphology, structure and function of RBC stored in vitro in type 2 diabetes rats. METHODS: Thirty SPF male SD rats, were randomly divided into 3 groups (n=10): non-T2DM conventional RBC preservation solution (group A), T2DM conventional RBC preservation solution (group B) and T2DM sodium pyruvate RBC preservation solution (group C). The leukoreduced RBC from the tail vein and stored for 0 d (T0), 7 d (T1), 14 d (T2), 21 d (T3) and 28 d (T4) to detect the morphology, structure and the contents of 2, 3-DPG, reactive oxygen species (ROS), malondialdehyde (MDA) and lactic acid (LA) of RBC in group A, B and C. The RBC stored for 14 days in vitro were labeled with PKH26, and its survival rate were tested in vivo at 1, 4, 10 and 16 hours after intravenous infusion. RESULTS: At T0, the RBC morphology of group A was intact, which was better than that of group B and group C. With the extension of storage time, the morphology of RBC in each group gradually transformed into a spindle-spherical shape. Compared with group A, the incidence of acanthocytes in group B and group C was higher, and the incidence of acanthocytes in group C was lower than that in group B. Compared with group A, the content of 2, 3-DPG in group B and group C decreased, while ROS and MDA increased at different time points (P<0.05). The content of 2,3-DPG in group C was higher than that in group B (P<0.05), and the contents of ROS and MDA were lower than those in group B (P<0.05). LA content in group B was higher than that in group A and group C (P<0.05). At T2-T4, the LA content in group C was lower than that in group A (P<0.05). The survival rate of RBC in group A was higher than that in group B and C, and the survival rate of RBC in group B was lower than that in group C (P<0.05). CONCLUSION: Sodium pyruvate added RBC preservation solution has a certain protective effect on RBC stored in vitro in type 2 diabetic rats, and its mechanism may be related to its antioxidant effect.

Objective To observe the effects of acute normovolemic hemodilution(ANH)on target-controlled infusion(TCI)of etomidate blood drug concentration and adrenal cortical function.Methods Sixty patients who undergo elective multisegmental spine surgery,35 males and 25 females,aged 30-60 years,BMI 20-25 kg/m2,ASA physical status Ⅰ or Ⅱ,were divided into two groups using random number table method:ANH group and control group,30 patients in each group.Both groups used a target-controlled infusion of etomidate for anesthesia induction and anesthesia maintenance.In the ANH group,ANH was performed after steady anesthesia induction,ideal Hct 28％to 30％,and transfused within 1 hour after surgery;the control group was routinely treated.The dosage of etomidate was recorded.Liquid chroma-tography-tandem mass spectrometry(LC-MS/MS)was used to detect etomidate blood concentrations at the immediate postoperative,10,20,and 30 minutes postoperative periods in the two groups,and the immedi-ate moment autologous blood collected into the storage bag,preserved in the storage bag for 1 hour,and the immediate moment transfused back in the ANH group.Plasma concentrations of cortisol(Cor),adrenocorti-cotropic hormone(ACTH),and aldosterone(ALD)were measured by chemiluminescence immunoassay(CLIA)before the induction of anesthesia,immediately after the operation,and at 1 day and 2 days postop-eratively.Results There was no significant difference in the total dosage of etomidate between the two groups.Compared with the immediate postoperative period,the plasma etomidate concentration was signifi-cantly decreased 10,20,and 30 minutes after surgery(P<0.05).Compared with the control group,the concentration increased significantly 10 minutes after surgery in the ANH group(P<0.05).The plasma concentrations of etomidate were(547.8±119.4)ng/ml at the immediate moment autologous blood collected into the storage bag,(536.7±107.8)ng/ml at the preserved in the storage bag for 1 hour,and(522.8±91.7)ng/ml at theimmediatemoment transfusedbackinthe ANHgroup.Comparedwithbeforein-duction of anesthesia,the concentration of Cor and ALD immediately after the operation decreased signifi-cantly(P<0.05)and the concentration of ACTH was significantly higher(P<0.05).There were no sta-tistically significant differences in the concentrations of Cor,ALD,and ACTH between the two groups before induction of anesthesia 1 day and 2 days postoperatively.Conclusion In the orthopedic surgery of TCI eto-midate,return transfusion of collected autologous blood transiently(about 10 minutes)increases etomidate blood concentrations,the function of adrenal cortical will recover to the preoperative level within 24 hours after the operation.

Objective:To evaluate the feasibility of using MRI-only simulation images for dose calculation of both photon and proton radiotherapy for nasopharyngeal carcinoma cases.Methods:T 1-weighted MRI images and CT images of 100 patients with nasopharyngeal carcinoma treated with radiotherapy in Cancer Hospital of Chinese Academy of Medical Sciences from January 2020 to December 2021 were retrospectively analyzed. MRI images were converted to generate pseudo-CT images by using deep learning network models. The training set, validation set and test set included 70 cases, 10 cases and 20 cases, respectively. Convolutional neural network (CNN) and cycle-consistent generative adversarial neural network (CycleGAN) were exploited. Quantitative assessment of image quality was conducted by using mean absolute error (MAE) and structural similarity (SSIM), etc. Dose assessment was performed by using 3D-gamma pass rate and dose-volume histogram (DVH). The quality of pseudo-CT images generated was statistically analyzed by Wilcoxon signed-rank test. Results:The MAE of the CNN and CycleGAN was (91.99±19.98) HU and (108.30±20.54) HU, and the SSIM was 0.97±0.01 and 0.96±0.01, respectively. In terms of dosimetry, the accuracy of pseudo-CT for photon dose calculation was higher than that of the proton plan. For CNN, the gamma pass rate (3 mm/3%) of the photon radiotherapy plan was 99.90%±0.13%. For CycleGAN, the value was 99.87%±0.34%. The gamma pass rates of proton radiotherapy plans were 98.65%±0.64% (CNN, 3 mm/3%) and 97.69%±0.86% (CycleGAN, 3 mm/3%). For DVH, the dose calculation accuracy in the photon plan of pseudo-CT was better than that of the proton plan.Conclusions:The deep learning-based model generated accurate pseudo-CT images from MR images. Most dosimetric differences were within clinically acceptable criteria for photon and proton radiotherapy, demonstrating the feasibility of an MRI-only workflow for radiotherapy of nasopharyngeal cancer. However, compared with the raw CT images, the error of the CT value in the nasal cavity of the pseudo-CT images was relatively large and special attention should be paid during clinical application.

Objective:To investigate the risk perception for risky behavior of HIV/AIDS infection among young students and to analyze the related influencing factors.Methods:A cross-sectional survey was conducted in 5 different types of Guangzhou colleges from September to November 2021, in which convenience sampling and a minimum number of classes per grade and 600 samples per school were used according to the national unity program. Disordered multi-classification logistic regression was used to construct a risk perception model and analyze influencing factors in different risk perception levels.Results:A total of 7 346 young students were surveyed, and most rated themselves at low risk of HIV/AIDS infections (90.58%, 6 654/7 346). A total of 89.10% (6 545/7 346) of subjects' perception of their HIV/AIDS infection risk was consistent with their risk behavior, while 10.90% (801/7 346) was inconsistent. Among those inconsistent subjects, 19.10% (153/801) showed underestimating their risk , while 80.90% (648/801) seen overestimating their risk. Disordered multi-classification logistic regression analysis showed that, after controlling for other factors, compared with the non-sexual group, respondents whose first sex age under 18 had a higher rate of underestimating their risk of infection ( OR=129.39, 95% CI: 73.28-228.48), as well as a higher rate of overestimated their risk of infection ( OR=1.76, 95% CI: 1.04-2.99). First sexual intercourse at age 18 or older was a risk factor for underestimating risk ( OR=70.56, 95% CI: 42.72-116.53), but was not statistically associated with overestimating risk. Being female, other school type, non-heterosexual orientation, and self-rated HIV-related knowledge as fair or no knowledge were risk factors for overestimating risk but were not statistically associated with underestimating risk. Conclusions:Overall, young students in universities of Guangzhou have a good risk perception of HIV/AIDS infection. Individual factors, education factors and sexual experience will influence students' risk perception of HIV/AIDS infection. Raising the awareness rate of HIV/AIDS knowledge and delaying the age of first sexual intercourse will improve the risk perception ability of young students.

Objective: To analyze the status of follow-up cell testing of HIV/AIDS cases among young students aged 15-24 in Guangdong Province from 2008 to 2019. Methods: Using the historical database downloaded from the AIDS Comprehensive Prevention and Control Information System from January 1, 2018 to December 31, 2019, eligible newly discovered cases were screened by year and were linked with follow-up database. Joinpoint regression model and trend test were used to explore the annual changes in the follow-up and CD4 testing status, and Logistic regression was used to analyze relevant influencing factors. Results: The number of infected students showed a rapid upward trend before 2015(APC=41.7，β=0.3，P<0.01), and the growth rate slowed down(APC=3.6，β=-0.3，P<0.01). The proportion of follow-up and CD4 testing completed within one year increased from 58.3% in 2008 to 93.6% in 2019, and the timely detection rate increased from 33.3% in 2008 to 86.2% in 2019. The Cochran Armitage trend test was statistically significant. Pairwise comparison test showed time trends of the idnex differed in regions and education groups (Z=4.7，8.7，9.8，P<0.01). The Pearl River Delta region, cases from other cities in the province, with precise transmission routes, from voluntary counseling and testing, and cases flowing within the province, the proportion of follow up and testing completed within one year is relatively high (P<0.05). Conclusion The growth rate of HIV/AIDS cases among young students aged 15-24 in Guangdong Province has slowed down in recent years. The route of infection, source and flow of cases affect follow-up and testing compliance. And to do a good job of referrals for off-site mobility, and explore and promote student-friendly VCT service models.

Objective:To design a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy.Methods:Applicator designing process is as follows: first, determined the shape of the applicator based on the geometric characteristics of the breast tumor bed closed to the chest wall; second, calculated the scattering angle and dose rate of the electron beam after passing through a series of scattering foils of different thicknesses to determine the thickness of the scattering foil; thrid, modeled the layer according to the applicator′s geometric characteristics where modulator located, and designed the modulator through the relationship between the geometric characteristics of the layer and the surface dose of the applicator. EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the layer, the applicator, and to calculate the dose distributions.Results:The applicator has two components. The upper component is a 3cm-diametre cylindrical collimator with 0.5cm wall made of 0.3cm steel and 0.2cm water equivalent material (WEM), a 0.13cm-foil made of tansgen. The lower component is a 4cm-diametre drum made of 0.2cm WEM and a 0.14cm maximum thickness hill-shaped modulator made of steel. When the energy of electron beam was 12MeV, the dose rate was about 90.44 cGy/min, and the depth of the 50% isodose curve was 1cm.Conclusion:The applicator is successfully designed, and can obtain a drum-shaped dose distribution.

Objective:To design a semi-spherical applicator for delivery of semi-spherical dose distributions and assess its dosemetric characteristics.Methods:The applicator was designed in the following way. First, the scattering angle and dose rate of the electron beam having passed through a series of scattering foils of different thicknesses were calculated to determine the thickness of the scattering foil. And then, a series of location model was designed, and the variances of the mean electron energy on the surface of these models were calculated to determine the foil location. Finally, the relationship between the geometric characteristics of the layer and the surface dose on the applicator was established to design the modulator. Monte Carlo (MC) codes EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the location model, the layer, the semi-spherical applicator, and to calculate the dose distributions.Results:A semi-spherical applicator was designed for electron beam of energy 12 MeV, which consisted of a 2.5 cm diametre cylindrical collimator with 0.5 cm thick wall made of 0.3 cm thick steel and 0.2 cm thick water equivalent material (WEM), a 0.14 cm-thick foil made of tansgen, and a 2.5 cm diametre hollow semi-sphere containing a crescent modulator made of WEM. The dose rate was about 160 cGy/min, and the depth of the 50% isodose curve was 0.85 cm.Conclutions:We designed and performed a MC simulation of a semi-spherical applicator to deliver a semi-spherical dose distribution from a high energy electron beam.