Objective To explore the impact of pH value of the reaction system on the properties of bovine hemoglobin modified with aldehydeated polyethylene glycol(PEG-bHb).Methods PEG-bHb conjugates were synthesized under varying pH conditions(6.0,6.5,7.4 and 8.0)of the reaction system while consistent molar ratios,temperature,and reaction time were maintained.The structural and functional attributes of PEG-bHb were characterized.Results The proportion of methemoglobin decreased with an increase in pH.In a weakly acidic reaction environment,the PEG-bHb was found to be relatively highly modified.At pH 6.5,the average number of PEG chains attached to the bHb surface was 6.86±0.38.Selective PEG modification of the N-terminal α-NH2 groups was more pronounced under weakly acidic conditions.Specifically,at pH 6.5,the modification efficiency of the N-terminal α-NH2 groups of bHb by aldehyde-activated PEG reached 95.4％for the α-chains and 99.3％for the β-chains.The PEG modification influenced the heme region microenvi-ronment of bHb,with minimal structural impact observed at pH 6.5.After modification,the oxygen affinity of PEG-bHb was enhanced,the Hill coefficient was reduced,and there were significant increases in colloid osmotic pressure,viscosity,and particle size,all of which differed markedly from the unmodified bHb group(P＜0.001).Conclusion The synthesis of PEG-bHb under weakly acidic conditions can result in a high degree of selective modification of the N-terminal α-NH2 groups and an overall high degree of modification.

Objective:To investigate the effect of miR-27b-3p on radiation resistance of breast cancer cells.Methods:The relative expression levels of miR-27b-3p in normal tissues and breast cancer tissues were analyzed through GEO database and verified by the qRT-PCR assay. Cloning formation, immunofluorescence, and EDU assay were used to assess the functions of miR-27b-3p on radioresistance of breast cancer cells. The luciferase reporter assay was used to verify whether miR-27b-3p directly targeted PLK2 mRNA. A rescue experiment was performed to identify the influence of PLK2 overexpression on miR-27b-3p regulated radioresistance.Results:The expression level of miR-27b-3p in both breast cancer tissues ( t=2.99, P<0.01) and breast cancer cells ( t=21.21, 32.88, P<0.05) was significantly higher than those in normal breast tissues and cells, especially, it was elevated in radioresistant MCF-7R cells ( t=25.63, P<0.05). Overexpression of miR-27b-3p enhanced the cloning efficiency of MCF-7 cells ( t=10.32, P<0.05), and had a protective effect on the proliferation of irradiated MCF-7 cells ( t=8.77, 8.26, 8.03, P<0.05). But interference of miR-27b-3p reduced the cloning efficiency and proliferation of MCF-7R cells ( t=40.00, P<0.05) after irradiation with different doses( t=8.54, 8.32, 8.23, P<0.05). Moreover, PLK2 was verified to be a direct target of miR-27b-3p, and overexpression of PLK2 inhibited miR-27b-3p-mediated radioresistance of breast cancer cells (MCF-7: t=9.66, P<0.05; MCF-7R: t=6.42, P<0.05). Conclusions:miR-27b-3p contributes to the radioresistance of breast cancer cells by targeting PLK2.

Objective:To investigate the application of modified mini-clinical evaluation exercise (Mini-CEX) in the probationary teaching of dermatology and venereology for eight-year program students.Methods:From 2019 to 2020, a modified Mini-CEX was used to grade 58 eight-year program students at the Third Affiliated Hospital of Sun Yat-Sen University at the early, middle, and late stages of the probationary teaching of dermatology and venereology. The modifications included refining various evaluation indicators. Specifically, medical history collection involved dynamic changes in rashes, negative symptoms with differential diagnostic significance, past history/personal history/family history, and other important medical history; physical examination involved the specialized condition of rashes, systematic physical examination, and negative signs with differential diagnostic significance; humanistic care involved caring for patients, health education, and privacy protection; clinical judgment involved principles of diagnosis, differential diagnosis, and treatment; communication skills involved proficiency, prioritization, and body language; organizational effectiveness involved time allocation, patient compliance, and preparation work; overall performance involved calmness and fluency, neat writing, and preliminary clinical thinking. SPSS 20.0 was used to perform the t test. Results:Compared with the early stage of probation, the 58 eight-year program students improved their scores in clinical comprehensive ability evaluation and scores in each specific evaluation at the middle and late stages of probation ( P < 0.001). The dynamic changes in rashes and the specialized situation of rashes (identification and description of rashes) were specific to this discipline. Conclusion:The modified Mini-CEX is an objective, comprehensive, concise, and efficient assessment tool, which meets the needs of teaching reform and practice of dermatology and venereology.

Objective:To establish a disease risk prediction model for the newborn screening system of inherited metabolic diseases by artificial intelligence technology.Methods:This was a retrospectively study. Newborn screening data ( n=5 907 547) from February 2010 to May 2019 from 31 hospitals in China and verified data ( n=3 028) from 34 hospitals of the same period were collected to establish the artificial intelligence model for the prediction of inherited metabolic diseases in neonates. The validity of the artificial intelligence disease risk prediction model was verified by 360 814 newborns ' screening data from January 2018 to September 2018 through a single-blind experiment. The effectiveness of the artificial intelligence disease risk prediction model was verified by comparing the detection rate of clinically confirmed cases, the positive rate of initial screening and the positive predictive value between the clinicians and the artificial intelligence prediction model of inherited metabolic diseases. Results:A total of 3 665 697 newborns ' screening data were collected including 3 019 cases ' positive data to establish the 16 artificial intelligence models for 32 inherited metabolic diseases. The single-blind experiment ( n=360 814) showed that 45 clinically diagnosed infants were detected by both artificial intelligence model and clinicians. A total of 2 684 cases were positive in tandem mass spectrometry screening and 1 694 cases were with high risk in artificial intelligence prediction model of inherited metabolic diseases, with the positive rates of tandem 0.74% (2 684/360 814)and 0.46% (1 694/360 814), respectively. Compared to clinicians, the positive rate of newborns was reduced by 36.89% (990/2 684) after the application of the artificial intelligence model, and the positive predictive values of clinicians and artificial intelligence prediction model of inherited metabolic diseases were 1.68% (45/2 684) and 2.66% (45/1 694) respectively. Conclusion:An accurate, fast, and the lower false positive rate auxiliary diagnosis system for neonatal inherited metabolic diseases by artificial intelligence technology has been established, which may have an important clinical value.

Clinical final examination is an important link in the standardized training of residents in dermatology and quantification of evaluation indicators is one of the important parameters. In this study, the scores of clinical examinations of six candidates who participated in standardized training of residents in dermatology of Sun Yat-Sen University in June 2019 were taken as examples to explore the quantitative indicators of standardized and multi-station clinical final examinations. The indicators contained four stations and five links: skin pathological reading, skin biopsy, medical history collection and physical examination, medical record writing, and comprehensive questioning, which covered the main contents of the standardized training outline of residents in dermatology. Each evaluation indicator was refined and quantified. Finally, heuristic ideas were put forward, including a wider range of standardized and multi-station clinical examinations, introduction of new examination places, and utilization of information technology.

Tissue inhibitor of metalloproteinases-2 (TIMP-2) inhibits tumor migration and invasion. Obtaining TIMP-2 protein is conducive to a comprehensive and in-depth study of its function and mechanism in tumorigenesis and development. We collected human TIMP-2 protein through prokaryotic expression in vitro. We expressed, purified and characterized human TIMP-2 protein. First, the human TIMP-2 gene was cloned from the cDNA obtained by reverse transcription of total RNA of human lung cancer A549 cells, and constructed to pET28a vector. The recombinant plasmid pET28a-TIMP-2 was transformed into Escherichia coli BL21(DE3) after restriction endonuclease digestion and sequencing analysis. The expression of TIMP-2 protein was induced by isopropyl-β-D-thiogalactoside (IPTG), and the expression conditions were optimized. After purification by nickel affinity column, the fusion protein His-TIMP-2 was identified by Western blotting method and its biological activity was detected by gelatin zymography. The fusion protein His-TIMP-2 existed in the form of inclusion body in E. coli. In a certain range, the concentration of IPTG had no significant effect on the expression amount of His-TIMP-2. But in this expression system, induction temperature and time were the key parameters, and the expression amount of His-TIMP-2 in E. coli increased with the increase of induction temperature. The purified and refolded fusion protein could effectively inhibit the activity of matrix metalloproteinases expressed by human lung cancer A549 cells. The acquisition of active fusion protein lays a foundation for further study of the function and mechanism of human TIMP-2, and is of great significance for tumor therapy.
Cloning, Molecular ; Escherichia coli/genetics* ; Humans ; Recombinant Fusion Proteins/genetics* ; Recombinant Proteins ; Tissue Inhibitor of Metalloproteinase-2/genetics*

Objective: To analyze changes in sensitivity of clinical strains of Ureaplasma urealyticum (Uu) to 9 kinds of common antibiotics from 2017 to 2018. Methods: The results of drug sensitivity testing of clinical Uu strains, which were isolated from 19 431 patients in Laboratory of Sexually Transmitted Disease (STD) , Department of Dermatology and Venereology, The Third Affiliated Hospital, Sun Yat-Sen University from 2007 to 2018, were analyzed retrospectively. Of the 19 431 patients, 6 076 were males, and 13 355 were females. Their age ranged from 15 to 68 years. The tested antibiotics included minocycline, doxycycline, erythromycin, azithromycin, clarithromycin, roxithromycin, ciprofloxacin, sparfloxacin and levofloxacin. Results: Resistance rates of clinical Uu strains to minocycline and doxycycline gradually decreased from 10.08% and 10.42% in 2007 to 1.15% and 2.61% in 2018, respectively, while sensitivity rates to minocycline and doxycycline gradually increased from 85.88% and 87.56% in 2007 to 97.02% and 96.42% in 2018, respectively. The resistance rate and sensitivity rate of clinical Uu strains to erythromycin fluctuated greatly during 2014—2017, with the resistance rate fluctuating around 20%, and the sensitivity rate fluctuating around 50%. The resistance rate of clinical Uu strains to azithromycin dropped rapidly from 42.02% in 2007 to 8.39% in 2011, and then fluctuated slightly around 10%. However, the sensitivity rate to azithromycin increased from 8.40% in 2007 to 86.05% in2011, and remained above 80% from then on to 2018. During 2007—2018, Uu strains showed low resistance rates (10%-20%) and high sensitivity rates to clarithromycin (80%-90%) , and the resistance and sensitivity rates to roxithromycin were similar to those to erythromycin. Uu strains showed constantly high resistance to ciprofloxacin (more than 80% after 2013) and low sensitivity (persistently less than 10%) . The sensitivity rate of clinical Uu strains to sparfloxacin fluctuated around 40%, while the resistance rate was maintained below 10% after 2011. The resistance and sensitivity rates of Uu strains to levofloxacin were similar to sparfloxacin, but the sensitivity rate to levofloxacin was relatively lower, which had been maintained at about 30%. Conclusion From 2007 to 2018, clinical Uu strains maintained a relatively stable low resistance rate and a high sensitivity rate to minocycline, doxycycline and clarithromycin, a high resistance rate and low sensitivity rate to ciprofloxacin, and a low resistance rate and sensitivity rate to sparfloxacin and levofloxacin; a relatively stable low resistance rate and a high sensitivity rate to azithromycin were achieved only after 2011; the resistance rate and sensitivity rate to erythromycin and roxithromycin fluctuated greatly.

Objective: To investigate the effect of square dance on bone mineral density and osphyarthrosis and gonitis in postmenopausal women. Methods: The postmenopausal women who danced on a square in the Second Hospital of Wuxi Affiliated to Nanjing Medical University from January 2014 to January 2015 were selected and divided into different groups by age.Each group of subjects received the bone mineral density test of their lumbar vertebral body 1-3, so as to analyze the difference between the bone mineral density of each vertebral body and the corresponding age, as well as the relationship between the age and the bone mineral density.The bone mineral density of their lumbar vertebrae was measured one year later, and the incidence rates of osphyarthrosis and gonitis were observed, thus the influence of square dancing on bone mineral density and the incidence of osphyarthrosis and gonitis of postmenopausal women was studied. Results: There was statistically significant difference in the bone mineral density for lumbar vertebrae of different age groups(F=74.213, P<0.01), among which the bone mineral density of lumbar vertebrae 1~3 in the age group of 45-60 showed a decreasing trend, with a medium negative correlation with age(r=0.978). After dancing on a square for 1 year, the bone mineral density of lumbar vertebral body 1-3 of subjects in the age group of 45-50, the age group of >50-55, the age group of >55~60, the age group of >60-65, the age group of >65-70 and the age group of over 70 were (149.51±31.65)mg/cm³, (118.98±34.55)mg/cm³, (103.56±23.44)mg/cm³, (86.88±34.21)mg/cm³, (69.89±29.72)mg/cm³, (61.22±34.21)mg/cm³, respectively, which increased slightly; the bone mineral density of the age group of 45-50, the age group of >50-55 and the age group of >55-60 increased significantly(F=8.012, 3.567, 4.774, all P<0.05). Square dancing had no significant effect on the incidence of osphyarthrosis and gonitis of postmenopausal women. Conclusion The age group of 45-60 is the most obvious period of bone mineral density decline for women.Square dancing can effectively improve the bone mineral density of postmenopausal women in this age group, but has no obvious effect on the improvement of the bone mineral density of women in other age groups.Square dancing has no effect on the incidence of osphyarthrosis and gonitis of postmenopausal women.

A total of 105 undergraduate students of the class 2014 majoring in clinical medicine in Sun Yat-Sen University received probation teaching in our department from October 2017 to May 2018,according to the syllabus of dermatology and venereology of clinical medicine.Senior teachers in our department were responsible for probation teaching,with the help of the independent wards in our department and probation teaching at the outpatient service.The teachers recorded the whole teaching process and evaluated the students' memory after probation.Through the teaching in wards and at the outpatient service,the students mastered the requirements in the syllabus of dermatology and venereology and achieved good results.

Taking the course's characteristics and advantages into account, this study explores the systematic implementation of standardized teaching rounds in the clinical probation sessions of the Dermatology and Venereology course , and evaluates its effect by analyzing the cases of 125 medical students from grade 2015 of Sun Yat-sen University . The results showed that the implementation of standardized teaching rounds has positive effect on the course.