Objective: To evaluate the effect of comprehensive prevention and control interventions for myopia among primary school students, so as to provide evidence for the comprehensive prevention and control of myopia among myopic students in schools. Methods: In September 2023, myopic students aged 6 to 11 years from Xilin South Road Primary School in Hohhot City were selected as research subjects by stratified random sampling method, and randomly divided into intervention group and control group. The control group received routine school management and conventional refractive correction. On the basis of routine care for the control group, the intervention group received comprehensive myopia prevention and control interventions covering health education, eye use behavior management, visual environment improvement, repeated low-level red-light therapy and auricular point pressing, with an intervention period of 12 months. Basic information, eye use behaviors and ophthalmic examination indicators were collected through questionnaire survey and ophthalmic examination. Generalized estimating equations were used to analyze the differences in eye use behaviors between the two groups of myopic primary school students before and after intervention, and linear mixed-effects models were used to analyze the differences in axial length (AL), spherical equivalent (SE) and uncorrected visual acuity (UCVA). Results: The control group included 52 students, including 25 boys and 27 girls, with an average age of (7.94±0.94) years. The intervention group included 52 students, including 27 boys and 25 girls, with an average age of (7.88±0.92) years. There were no statistically significant differences in baseline data such as gender, age, AL, SE and UCVA between the two groups (all P>0.05). There were statistically significant interaction effects between group and time on the compliance rate of screen time and outdoor activity time in the two groups (both P<0.05). After intervention, the compliance rates of screen time and outdoor activity time in the intervention group were higher than in the control group (51.92% vs. 28.85%, 69.23% vs. 50.00%). There were statistically significant interaction effects between group and time on AL, SE and UCVA (all P<0.05). After intervention, the AL increase was lower in the intervention group than in the control group (0.17 mm vs. 0.34 mm), the decreases in SE and UCVA were lower in the intervention group than in the control group (0.12 D vs. 0.42 D, 0.03 vs. 0.12). Conclusion The comprehensive myopia prevention and control measures have intervention effects on myopia prevention and control among primary school students, which can slow down the axial elongation and the progression of refractive status, and improve uncorrected visual acuity and some eye use behaviors.

Although there are 125 predicted DNase Ⅱ-like family genes in the Trichinella spiralis genome, plancitoxin-1-like (Ts-Pt) contains the HKD motif, a typical conserved region of DNase Ⅱ, in N- and C-terminal. It is generally believed that histidine is the active site in DNase Ⅱ. To study the nuclease activity of recombinant Ts-Pt with mutations in the active site from T. spiralis, different fragments of the mutated Ts-Pt genes were cloned using overlap PCR technique and inserted into the expressing vector pET-28a(+), and transformed into Escherichia coli Rosseta (DE3). The fusion proteins were purified by Ni-NTA affinity chromatography and SDS-PAGE. Nuclease activity of the recombinant proteins was detected by agarose gel electrophoresis and nuclease-zymography. The recombinant plasmids harboring the mutated Ts-Pt genes were constructed and expressed as inclusive body in a prokaryotic expression system. After renaturation in vitro, the recombinant proteins had no nuclease activity according to agarose gel electrophoresis. However, the expressed proteins as inclusive body displayed the ability to degrade DNA after renaturation in gel. And the nuclease activity was not affected after subjected to mutation of active site in N- and C-termini of Ts-Pt. These results provide the basis to study the relationship between DNase Ⅱ-like protein family and infection of T. spiralis.