Objective To investigate the structure of deoxyhypusine synthase(DHS)in Saccharomyces cerevisiae(Dys1)and unravel the molecular mechanism of hypusine lysine modification,providing a theoretical basis for the treatment of highly proliferative diseases such as human immunodeficiency virus type 1(HIV-1)replication.Meth-ods Using the E.coli BL21 expression system,an in vitro expression vector was constructed and used to express the protein of Dys1.Dys1 protein samples were purified using methods such as affinity chromatography and molecu-lar sieving to achieve protein purification and isolation.The crystals of Dys1 were obtained using the crystallized so-lution containing 6％Polyethylene Glycol(PEG)8000,0.1 mol/L N-2-hydroxyethylpiperazine-N-ethane-sulphoni-cacid(Hepes)pH 6.5,and 8％ethylene glycol.The crystal structure of Dys1 was resolved at a resolution of 2.8 ? using X-ray crystallography.The structural analysis was performed with CCP4i and Coot software.Results The overall structure of Dys1 was a tetramer,each monomer containing a catalytic site and a cofactor NAD+binding site.The core region of the monomer adopted a Rossmann fold.The amino acid residues involved in the substrate binding sites were highly conserved among eukaryotes.Conclusion The crystal structure of Dys1 is being resolved for the first time.It reveals the binding mode of the cofactor NAD+to the enzyme and confirms that the enzyme functions as a tetramer,with the N-terminus serving as an essential modulator for its catalytic activity.

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7),and study its biomechanical properties under muscle force by cervical traction,so as to provide references for clinical treatment.Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods,cervical traction at the extension angle of 0°,10°,20°,30°,40° under the same traction weight,was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model.Results In the process of cervical extension by traction,under the muscle force,the average maximum equivalent stress of cervical vertebrae,intervertebral disc and uncovertebral joints increased by 4.86,1.79,0.69 MPa,respectively,and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 1 1.1,1.26 mm,respectively.The biomechanical properties of cervical traction were similar to the FEA results reported in the literature.Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae,intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic.In addition,the traction angle should not be too large:0.-20. is generally recommended as a relatively safe angle range at the initial stage.

OBJECTIVE: To evaluate the suitability of two pretreatment methods, the nitric acid digestion method and the elution method, and two measurement modes of inductively coupled plasma-mass spectrometry(ICP-MS), the No gas mode and the helium collision(He) mode, for the determination of lithium and its compounds in the workplace air. METHODS: We collected lithium and its compounds in the air of the workplace using the microporous filter membrane, and two pretreatment methods, the nitric acid digestion and elution methods were used for processing, and measured with the No gas mode and the He mode of ICP-MS. RESULTS: The good linearity range of lithium concentration in No gas mode and He mode of ICP-MS method was 0.00-500.00 μg/L, and the correlation coefficient was 0.999. The detection limit and the lower limit of quantification of lithium were 0.04 and 0.13 μg/L respectively in the No gas mode. In He gas mode: they were 0.12 and 0.39 μg/L respectively. Using the nitric acid digestion method for pre-treatment, the recovery rate of lithium addition was 96.9%-104.9%; the within-run and the between-run relative standard deviations were 3.3%-5.0% and 2.9%-5.3% respectively. Using the elution method for pre-treatment, the recovery rate of lithium addition was 97.6%-102.1%; the within-run and the between-run relative standard deviation were 3.3%-4.6% and 3.4%-4.8%, respectively. The sample could be stored at room temperature for at least 14 days. CONCLUSION: The ICP-MS method can be used as a new technology for detecting lithium and its compounds in the air of workplace. It is recommended that the elution method and the No gas mode be the first choice when measuring lithium and its compounds.

Objective: To understand the volatile organic components in the organic solvents used by enterprises in Baoan District, Shenzhen. Methods: From January to December 2020, a total of 541 organic solvent samples used by 86 companies were collected for volatile organic component analysis, and the main volatile components and high-risk occupational hazards in organic solvents used in different industries were analyzed. Results: A total of 201 volatile organic components were detected in 541 organic solvents. The top 5 components detected include xylene (29.76%, 116/541), toluene (21.81%, 118/541), methanol (20.70%, 112/541), n-hexane (14.79%, 80/541) and ethylbenzene (14.23%, 77/541). The detection rates of benzene, trichloroethylene, n-hexane, and 1, 2-dichloroethane, which were high-risk occupational hazards, were 2.40% (13/541), 3.70% (20/541), 14.79% (80/541), and 1.66% (9/541), respectively. The volatile components in organic solvents used in different industries was different. Benzene is more frequently detected in organic solvents used in the printing industry, trichloroethylene was more frequently detected in organic solvents used in the electronics industry, and n-hexane was more commonly found in organic solvents used in the electronics industry, printing and other industries, and 1, 2-dichloroethane has been more frequently detected in organic solvents used in the machinery industry. Conclusion: There are many types of organic solvents used by enterprises in Bao'an District, with complex components and differences in different industries.
Benzene/analysis* ; Hexanes ; Solvents ; Industry ; Trichloroethylene

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7), and study its biomechanical properties under muscle force by cervical traction, so as to provide references for clinical treatment. Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods, cervical traction at the extension angle of 0°, 10°, 20°, 30°, 40° under the same traction weight, was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model. Results In the process of cervical extension by traction, under the muscle force, the average maximum equivalent stress of cervical vertebrae, intervertebral disc and uncovertebral joints increased by 4.86, 1.79, 0.69 MPa, respectively, and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 11.1, 1.26 mm, respectively. The biomechanical properties of cervical traction were similar to the FEA results reported in the literature. Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae, intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic. In addition, the traction angle should not be too large: 0°-20° is generally recommended as a relatively safe angle range at the initial stage.

Objective To observe changes of surface electromyography (sEMG) in cervical traction under different loading weight and at different angles, and compare the muscle activity changes obtained by experiment with simulation results obtained by AnyBody cervical modeling, so as to verify the rationality of the simulation results. Methods Ten young volunteers with supine cervical traction were selected to test the sEMG signals of bilateral sternocleidomastoid (SCM) and upper trapezius (UT) muscles by using the JE-TB0810 surface EMG device. The average EMG (AEMG) and mean power frequency (MPF) were used to analyze the variation patterns of sEMG in cervical spine. Results The AEMG values of SCM and UT muscles increased as the loading weight and traction angles increasing, with a statistically significant difference (P<0.05). The AEMG values of UT muscles was higher than that of SCM muscles, also with a statistically significant difference (P<0.05). No statistical differences were found in the MPF values at different traction angles and under different loading weight for both SCM and UT muscles (P>0.05). The experimental results were consistent with muscle force activity characteristics of SCM and UT muscles by modeling and simulation of cervical traction. Conclusions The simulation results are reasonable. The traction weight should be loaded reasonably according to the excitation and fatigue of the cervical muscles in clinic. This can both reach the treatment effect and improve the patient’s comfort, which will provide an important reference for further development and improvement of the cervical traction device.

Objective: To study the effects of superficial temporal artery and vein as recipient vessels for the free anterolateral thigh flap on the appearance and functions after maxillectomy. Methods: Clinical data of 21 patients with malignant maxillary tumors in Department of Oral and Maxillofacial Surgery, the Second Xiangya Hospital of Central South University from January 2014 to November 2019, who were treated by free anterolateral thigh flap with temporal superficial vessels as the recipient vessels were analyzed retrospectively. There were 18 males and 3 females, with the age ranging from 29 to 73 years old, including 19 cases of squamous carcinoma, 1 case of adenoid cystic carcinoma and 1 case of osteosarcoma. Of those 7 patients underwent primary surgery, 14 patients received resurgery, and 6 patients had a history of postoperative radiotherapy and chemotherapy. Among 14 patients with resurgery, 13 had recurrent ipsilateral second site tumor and 1 had recurrent tumor, and all of them received the maxillectomy and reconstructive surgery with the free anterolateral thigh flap. Patients were evaluated with water swallow test and speech intelligibility score in 1, 3 and 6 months after operation. The data were statistically analyzed with SPSS 22.0 statistical software. Water swallow test results before and after operation were compared using the Wilcoxon rank sum test. The mean speech intelligibility scores before and after operation were compared by the paired t test. Results: Patients were followed up for 10-60 months. All free flaps survived after operation. No diplopia occurred. Breathing, swallowing and speaking functions were normal. No movement disorders caused by the donor of thigh flap. Water swallow test showed no phenomenon of water flowing into the nasal cavity or oral and nasal leakage with level Ⅰ for 4 cases, level Ⅱ for 13 cases, level Ⅲ for 3 cases and level Ⅳ for 1 case. The mean speech intelligibility scores before surgery and 1, 3 and 6 months after surgery were 4.31±0.13, 1.46±0.21, 2.15±0.45 and 2.87±0.76 respectively. There was statistically significant difference in the mean speech intelligibility scores between 1 and 6 months after surgery (F=78.456, P<0.05). Conclusion: It is safe and reliable to use the superficial temporal vessels as recipient vessels for free anterolateral thigh flap in the reconstruction of defect after maxillectomy in malignant tumors, with good outcomes of functions and a satisfactory restoration of outward appearance.
Adult ; Aged ; Female ; Free Tissue Flaps ; Humans ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Reconstructive Surgical Procedures ; Retrospective Studies ; Skin Transplantation ; Thigh/surgery*

Primary signet ring cell carcinoma (SRCC) of the prostate is a rare neoplasm. However, its potential tumorigenic mechanism, clinicopathological features, and prognostic outcome have not been systematically described. To determine the pathogenic mechanism, we detected distributions of programmed cell death-ligand 1 (PD-L1), programmed death 1 (PD-1), and cellular components in the tumor microenvironment, including tumor-infiltrating lymphocytes (CD4 and CD8), tumor-associated macrophages (TAMs; CD163 and CD68), and tumor-associated fibroblasts (vimentin and alpha-smooth muscle actin [α-SMA]), in tumor tissues from four patients with primary prostatic SRCC compared with corresponding adjacent tissues and tumor tissues from 30 patients with prostate adenocarcinoma (PCa) by immunohistochemical staining. We found higher expression of PD-L1, CD163, and CD68 in primary SRCC specimens than that in both corresponding adjacent nontumor specimens and PCa specimens with different Gleason scores, indicating that TAMs may participate in the malignant biological behavior of primary SRCC of the prostate. For further analysis, we searched electronic journal databases and Surveillance, Epidemiology, and End Results (SEER) to identify 200 eligible patients including our four cases. According to Kaplan-Meier survival curve analysis, patients <68 years old, with radical prostatectomy (RP), Gleason score of 7-8, and lower clinical stage had longer overall survival (OS). Moreover, Cox multivariate analysis indicated that race (hazard ratio [HR] = 1.422), surgical approach (HR = 1.654), and Gleason score (HR = 2.162) were independent prognostic factors for OS. Therefore, primary SRCC of the prostate represents a distinct and aggressive subtype of prostate cancer associated with a higher distribution of PD-L1 and TAMs, which warrants further clinical investigation.
Aged ; B7-H1 Antigen ; Carcinoma, Signet Ring Cell ; Humans ; Lymphocytes, Tumor-Infiltrating ; Male ; Prognosis ; Prostate ; Prostatic Neoplasms ; Tumor Microenvironment