Objective: To determine the distribution characteristics of waist circumference (WC), waist height ratio (WHtR) of 6–18 years olds in Guangzhou, and to put forward the WC and WHtR appropriate boundary values for 6–18 years olds on the basis of cardiovascular disease (CVD) risk factor assessment. Methods: We analyzed the height, weight, WC and its metabolic indication data (blood pressure, fasting blood glucose, and blood lipids) of 15 000 children in Guangzhou, aged 6–18, with the receiver-operating characteristic curve (ROC), and explored the best value point of WC and WHtRfor the prediction of cardiovascular diseases. Results: When the WC percent reached P85, and WHtR reached 0.48, the cardiovascular risk factors of fasting blood-glucose, blood pressure, and blood fat were signiifcantly higher. Conclusion: The 85th percentile value of WC and 0.48 of WHtR are the appropriate boundary values in increasing the cardiovascular disease risk factors in Chinese children and teenagers. WC and WHtR as a relatively simple inspection method, can well predict cardiovascular diseases, and be used in the conventional measuring items among students.

BACKGROUND:Changes in skeletal muscle mass have been indicated in studies addressing the effects of low-frequency pulsed magnetic fields on the structure and morphology of the skeletal muscle,but no relevant studies have been conducted on the morphologic changes that occur after chronic exposure to the low-frequency pulsed magnetic field. OBJECTIVE:To observe the effects of chronic exposure to low-frequency pulsed magnetic fields on the maximal voluntary contraction and morphologic indicators of the quadriceps muscle of the leg,thereby providing a reference of muscle morphologic changes for the use of this technique as a strategy for muscle function improvement. METHODS:Seventy healthy subjects were recruited and randomly divided into a test group that received magnetic field stimulation and a control group that underwent sham treatment,with 35 subjects in each group,and the total duration of the trial was 4 weeks.The test group underwent low-frequency pulsed magnetic stimulation for 15 minutes every 48 hours,while the control group underwent sham treatment,with the same intervention interval and duration as the test group.After 4 weeks of intervention,changes in the maximum voluntary contraction value of the quadriceps muscle in different groups were observed,and B-mode ultrasonography was utilized as a means of assessment to observe changes in muscle thickness,muscle cross-sectional area,and pinnation angle indexes. RESULTS AND CONCLUSION:After 4 weeks of chronic exposure to low-frequency pulsed magnetic fields,68 subjects completed the test.The maximum voluntary contraction value of the quadriceps muscle in the test group increased significantly(P=0.000),and the increment was significantly higher than that of the control group(P=0.008).Three indexes related to muscle morphology in the test group were significantly higher than the pre-test values(P=0.000),while in the control group,muscle thickness showed a significant reduction(P=0.020),there was no significant change in the pinnation angle,but a significant increase in the cross-sectional area(P=0.000).Intergroup comparisons revealed that the three indicators related to muscle morphology,including muscle thickness(P=0.012),pinnation angle(P=0.003),and cross-sectional area(P=0.049),were significantly higher in the test group than in the control group.The above data confirmed that the maximum voluntary contraction of the quadriceps muscle was significantly increased in healthy adults after 4 weeks of chronic exposure to the low-frequency pulsed magnetic field,and significant increases in the three muscle morphometric indices of muscle thickness,cross-sectional area,and pinnation angle were observed in the test group,providing a basis of muscle tissue morphology for the use of this technique as an exercise alternative and medical treatment strategy for muscle improvement.

BACKGROUND:Muscle weakness is a common symptom after coronavirus disease 2019(COVID-19)infection and affects the ability to perform daily activities in humans during recovery.Low-frequency pulsed magnetic field stimulation at a strength of 1.5 mT and a frequency of 3 300 Hz can enhance the maximal voluntary contraction and strength endurance of human skeletal muscle by inducing and activating classical transient receptor potential channel 1(TRPC1),which produces a series of pathological support effects on muscle tissue.It has not been studied whether this means will improve muscle weakness in patients recovering from COVID-19. OBJECTIVE:To select the low-frequency pulsed magnetic field for magnetic stimulation of lower limb muscle groups in patients with COVID-19,in order to observe the effect of this stimulation on the improvement of muscle weakness of lower limb muscle groups in patients with COVID-19 during the recovery period. METHODS:Fourteen patients infected with COVID-19(Omicron strain)positive for Innovita COVID-19 Ab Test(Colloidal Gold)and accompanied by muscle weakness were recruited and randomly divided into two groups:a test group receiving magnetic field stimulation and a control group receiving sham treatment,respectively.The total duration of the trial was 3 weeks.The test group was given low-frequency pulsed magnetic stimulation of the lower limbs every 48 hours and the control group was given the same intervention procedure as the test group but with sham stimulation.Patients in both groups were not informed whether the magnetic stimulation apparatus was running or not.Nine sessions were performed in both groups and the changes in the maximum voluntary contraction,explosive leg force and strength endurance of the local muscle groups of the lower limbs were subsequently observed in both groups. RESULTS AND CONCLUSION:Among the eight local muscle groups collected,seven local muscle groups in the test group showed an increase in the maximum voluntary contraction value after 3 weeks of low-frequency pulsed magnetic field stimulation.In the control group,there were only three muscle groups with improvement in the maximum voluntary contraction.The rate of improvement in the anterior and posterior muscle groups of the left leg in the test group was significantly higher than that in the control group.The longitudinal jump height and peak angular velocity of the knee joint in both groups were improved compared with the pre-test measurement,and the elevation rate of jumping height in the test group was higher than that in the control group.Under the fatigue condition,the decline rates of peak angular velocity of the knee joint and jumping height in the test group decreased significantly,while those in the control group did not change significantly.The above data confirmed that the low-frequency pulsed magnetic field stimulation with the intensity of 1.5 mT and frequency of 3 300 Hz could improve the muscle strength of more local muscle groups in the lower limbs of patients with COVID-19 during the recovery period compared with the human self-healing process,and the whole-body coordination ability and functional status based on explosive leg force of the legs could be significantly improved.Therefore,low-frequency pulsed magnetic field stimulation can be used as an effective,non-exercise rehabilitation tool to improve muscle weakness in the lower limbs of patients with COVID-19.

Numerous studies on cancers, biopharmaceuticals, and clinical trials have necessitated comprehensive and precise analysis of protein O-glycosylation. However, the lack of updated and convenient databases deters the storage of and reference to emerging O-glycoprotein data. To resolve this issue, an O-glycoprotein repository named OGP was established in this work. It was constructed with a collection of O-glycoprotein data from different sources. OGP contains 9354 O-glycosylation sites and 11,633 site-specific O-glycans mapping to 2133 O-glycoproteins, and it is the largest O-glycoprotein repository thus far. Based on the recorded O-glycosylation sites, an O-glycosylation site prediction tool was developed. Moreover, an OGP-based website is already available (http://www.oglyp.org/). The website comprises four specially designed and user-friendly modules:statistical analysis, database search, site prediction, and data submission. The first version of OGP repository and the website allow users to obtain various O-glycoprotein-related information, such as protein accession Nos., O-glycosylation sites, O-glycopeptide sequences, site-specific O-glycan structures, experimental methods, and potential O-glycosylation sites. O-glycosylation data mining can be performed efficiently on this website, which will greatly facilitate related studies. In addition, the database is accessible from OGP website (http://www.oglyp.org/download.php).