Control of polymers' amorphous-crystalline transition enables miniaturization and multifunctional integration for hydrogel bioelectronics.

Soft bioelectronic devices exhibit motion-adaptive properties for neural interfaces to investigate complex neural circuits. Here, we develop a fabrication approach through the control of metamorphic polymers' amorphous-crystalline transition to miniaturize and integrate multiple components into hydrogel bioelectronics. We attain an about 80% diameter reduction in chemically cross-linked polyvinyl alcohol hydrogel fibers in a fully hydrated state. This strategy allows regulation of hydrogel properties, including refractive index (1.37-1.40 at 480 nm), light transmission (>96%), stretchability (139-169%), bending stiffness (4.6 ± 1.4 N/m), and elastic modulus (2.8-9.3 MPa). To exploit the applications, we apply step-index hydrogel optical probes in the mouse ventral tegmental area, coupled with fiber photometry recordings and social behavioral assays. Additionally, we fabricate carbon nanotubes-PVA hydrogel microelectrodes by incorporating conductive nanomaterials in hydrogel for spontaneous neural activities recording. We enable simultaneous optogenetic stimulation and electrophysiological recordings of light-triggered neural activities in Channelrhodopsin-2 transgenic mice.

Biologically Driven In Vivo Occlusion Design Provides a Reliable Experimental Glaucoma Model.

Fluid flow transport through the trabecular meshwork tissues is a major regulator of intraocular pressure (IOP) modulation in healthy and glaucomatous individuals. Microbead occlusion models of ocular hypertension regulate aqueous humor drainage to induce high IOP to allow for in vivo study of pressure-related glaucomatous pathology. However, the reliability and application of current injectable microbeads are hindered by inadequate design of the beads-tissue interfaces to maintain a stable IOP elevation over the long term. Considering the graded, porous architecture and fluid transport of the trabecular meshwork, we developed a tailored, injectable "viscobeads" technique, which induced a sustained elevation of IOP for at least 8 weeks. These composite viscobeads contain a non-degradable polystyrene (PS) core for structural support and a biodegradable polylactic-co-glycolic acid (PLGA) viscoelastic surface. This approach enhances the obstruction of aqueous humor drainage through heterogeneous sizes of trabecular meshwork fenestrations and reliably modulates the magnitude and duration of ocular hypertension. In a mouse model, a single viscobeads injection resulted in sustained IOP elevation (average 21.4±1.39 mm Hg), leading to a 34% retinal ganglion cell (RGC) loss by 56 days. In an earlier stage of glaucoma progression, we conducted non-invasive electroretinography (ERG) recording and revealed glaucomatous progression by analyzing high-frequency oscillatory potentials. To further explore the application of the viscobeads glaucoma models, we assayed a series of genes through adeno-associated virus (AAV)-mediated screening in mice and assessed the impact of genetic manipulation on RGC survivals. CRISPR mediated disruption of the genes, PTEN, ATF3 and CHOP enhanced RGC survival while LIN 28 disruption negatively impacted RGC survival. This biologically driven viscobeads design provides an accessible approach to investigate chronic intraocular hypertension and glaucoma-like neurodegeneration and ultimately tenders the opportunity to evaluate genetic and pharmacological therapeutics.

Mechanistic engineering of celastrol liposomes induces ferroptosis and apoptosis by directly targeting VDAC2 in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of most common and deadliest malignancies. Celastrol (Cel), a natural product derived from the Tripterygium wilfordii plant, has been extensively researched for its potential effectiveness in fighting cancer. However, its clinical application has been hindered by the unclear mechanism of action. Here, we used chemical proteomics to identify the direct targets of Cel and enhanced its targetability and anti-tumor capacity by developing a Cel-based liposomes in HCC. We demonstrated that Cel selectively targets the voltage-dependent anion channel 2 (VDAC2). Cel directly binds to the cysteine residues of VDAC2, and induces cytochrome C release via dysregulating VDAC2-mediated mitochondrial permeability transition pore (mPTP) function. We further found that Cel induces ROS-mediated ferroptosis and apoptosis in HCC cells. Moreover, coencapsulation of Cel into alkyl glucoside-modified liposomes (AGCL) improved its antitumor efficacy and minimized its side effects. AGCL has been shown to effectively suppress the proliferation of tumor cells. In a xenograft nude mice experiment, AGCL significantly inhibited tumor growth and promoted apoptosis. Our findings reveal that Cel directly targets VDAC2 to induce mitochondria-dependent cell death, while the Cel liposomes enhance its targetability and reduces side effects. Overall, Cel shows promise as a therapeutic agent for HCC.

Fatigue-resistant hydrogel optical fibers enable peripheral nerve optogenetics during locomotion.

We develop soft and stretchable fatigue-resistant hydrogel optical fibers that enable optogenetic modulation of peripheral nerves in naturally behaving animals during persistent locomotion. The formation of polymeric nanocrystalline domains within the hydrogels yields fibers with low optical losses of 1.07 dB cm-1, Young's modulus of 1.6 MPa, stretchability of 200% and fatigue strength of 1.4 MPa against 30,000 stretch cycles. The hydrogel fibers permitted light delivery to the sciatic nerve, optogenetically activating hindlimb muscles in Thy1::ChR2 mice during 6-week voluntary wheel running assays while experiencing repeated deformation. The fibers additionally enabled optical inhibition of pain hypersensitivity in an inflammatory model in TRPV1::NpHR mice over an 8-week period. Our hydrogel fibers offer a motion-adaptable and robust solution to peripheral nerve optogenetics, facilitating the investigation of somatosensation.

A nanoscale inorganic coating strategy for stabilizing hydrogel neural probes in vivo.

Hydrogels with adaptable optical and mechanical characteristics show considerable promise for light delivery in vivo with neuroengineering applications. However, the unlinked amorphous polymer chains within hydrogels can cause volumetric swelling after water absorption under physiological conditions over time. Chemically cross-linked poly(vinyl alcohol) (PVA) hydrogels showcase fatigue-resistant attributes and promising biocompatibility for the manufacture of soft neural probes. However, possible swelling of the PVA hydrogel matrix could impact the structural stability of hydrogel-based bioelectronics and their long-term in vivo functionality. In this study, we utilized an atomic layer deposition (ALD) technique to generate an inorganic, silicon dioxide (SiO2) coating layer on chemically cross-linked PVA hydrogel fibers. To evaluate the stability of SiO2-coated PVA hydrogel fibers mimicking the in vivo environment, we conducted accelerated stability tests. SiO2-coated PVA hydrogel fibers showed improved stability over a one-week incubation period under a harsh environment, preventing swelling and preserving their mechanical and optical properties compared to uncoated fibers. These SiO2-coated PVA hydrogel fibers demonstrated nanoscale polymeric crystalline domains (6.5 ± 0.1 nm), an elastic modulus of 73.7 ± 31.7 MPa, a maximum elongation of 113.6 ± 24.2%, and minimal light transmission loss (1.9 ± 0.2 dB cm-1). Lastly, we applied these SiO2-coated PVA hydrogel fibers in vivo to optically activate the motor cortex of transgenic Thy1::ChR2 mice during locomotor behavioral tests. This mouse cohort was genetically modified to express the light-sensitive ion channel, channelrhodopsin-2 (ChR2), and implanted with hydrogel fibers to deliver light to the motor cortex area (M2). Light stimulation via hydrogel fibers resulted in optogenetically modulated mouse locomotor behaviors, including increased contralateral rotation, mobility speeds, and travel distances.

Control of Polymers' Amorphous-crystalline Transition for Hydrogel Bioelectronics Miniaturization and Multifunctional Integration.

Bioelectronic devices made of soft elastic materials exhibit motion-adaptive properties suitable for brain-machine interfaces and for investigating complex neural circuits. While two-dimensional microfabrication strategies enable miniaturizing devices to access delicate nerve structures, creating 3D architecture for expansive implementation requires more accessible and scalable manufacturing approaches. Here we present a fabrication strategy through the control of metamorphic polymers' amorphous-crystalline transition (COMPACT), for hydrogel bioelectronics with miniaturized fiber shape and multifunctional interrogation of neural circuits. By introducing multiple cross-linkers, acidification treatment, and oriented polymeric crystalline growth under deformation, we observed about an 80% diameter decrease in chemically cross-linked polyvinyl alcohol (PVA) hydrogel fibers, stably maintained in a fully hydrated state. We revealed that the addition of cross-linkers and acidification facilitated the oriented polymetric crystalline growth under mechanical stretching, which contributed to the desired hydrogel fiber diameter decrease. Our approach enabled the control of hydrogels' properties, including refractive index (RI 1.37-1.40 at 480 nm), light transmission (> 96%), stretchability (95% - 111%), and elastic modulus (10-63 MPa). To exploit these properties, we fabricated step-index hydrogel optical probes with contrasting RIs and applied them in optogenetics and photometric recordings in the mouse brain region of the ventral tegmental area (VTA) with concurrent social behavioral assessment. To extend COMPACT hydrogel multifunctional scaffolds to assimilate conductive nanomaterials and integrate multiple components of optical waveguide and electrodes, we developed carbon nanotubes (CNTs)-PVA hydrogel microelectrodes for hindlimb muscle electromyographic and brain electrophysiological recordings of light-triggered neural activities in transgenic mice expressing Channelrhodopsin-2 (ChR2).

The effectiveness of an online sexuality education module in promoting sexual knowledge and attitude change: a cluster randomized controlled trial.

This study assesses the ability of an online sexuality education (OSE) module ('You and Me') to enhance sexual and reproductive health (SRH) knowledge and attitudes among 10th-grade vocational high school students in China. We conducted a cluster randomized controlled trial, randomizing 29 vocational high schools to (i) receiving the module (intervention) or (ii) not receiving the module (control). Students completed a baseline questionnaire, then completed the module within 8 weeks and then completed a follow-up questionnaire within the following 2 weeks. We assessed the differences in intervention effects using hierarchical linear modeling. No significant differences between intervention and control groups were found for knowledge and attitude scores at baseline among the 2985 students included in the analyses. For the intervention group at follow-up, we observed significant improvements in SRH knowledge scores of approximately 20% for boys and girls although girls responded to the module with larger knowledge gains than boys. At follow-up, intervention group students also had higher SRH attitude scores toward views that are more contemporary than the control group. In addition, girls held more contemporary attitudes than boys. The comprehensive OSE module assessed is effective in improving SRH knowledge, and attitude among Chinese vocational high school students after the module is completed.

Vanadium-Tailored Silicon Composite with Furthered Ion Diffusion Behaviors for Longevity Lithium-Ion Storage.

As one of the promising anode materials, silicon has attracted much attention due to its high theoretical specific capacity (∼3579 mAh g-1) and suitable lithium alloying voltage (0.1-0.4 V). Nevertheless, the enormous volume expansion (∼300%) in the process of lithium alloying has a great negative effect on its cyclic stability, which seriously restricts the large-scale industrial preparation of silicon anodes. Herein, we design a facile synthesis strategy combining vanadium doping and carbon coating to prepare a silicon-based composite (V-Si@C). The prepared V-Si@C composite does not merely show improved conductivity but also improved electrochemical kinetics, attributed to the enlarged lattice spacing by V doping. Additionally, the superiority of this doping strategy accompanied by microstructure change is embodied in the relieved volume changes during the repeated charging/discharging process. Notably, the initial capacity of the advanced V-Si@C electrode is 904 mAh g-1 (1 A g-1) and still holds at 1216 mAh g-1 even after 600 cycles, showing superior electrochemical performance. This study offers an alternative direction for the large-scale preparation of high-performance silicon-based anodes.

Prevalence and factors influencing adolescent idiopathic scoliosis in Zhongshan City / 中国学校卫生

Objective@#To investigate factors influencing adolescent idiopathic scoliosis (AIS), and to provide a scientific basis for effective prevention and treatment programs.@*Methods@#A questionnaire survey was conducted among 6 757 students who participated in the scoliosis screening program for primary and middle school students in Zhongshan City, China from April 2019 to March 2020. Visual examination and Adams flexion test were used to measure the rotation angle of trunk. For each student, individual and family demographics, family history of scoliosis, daily postural habits, school bag carrying habits, vision, health, school environment, and physical activity were collected by questionnaire. Factors influencing AIS were analyzed using Chi square test and multivariate Logistic regression.@*Results@#The positive screening rate for AIS was 2.0%(135 cases). Multivariate Logistic regression analysis revealed that female gender, no family history of AIS, standing with lumbar spine tilted forward, habit of leaning to the left when seated, and a monthly family income of >10 000 yuan were related to the occurrence of AIS in adolescents ( OR =3.01, 0.38, 2.29, 1.74, 0.44, P <0.05).@*Conclusion@#Female students aged 10-16 years with a family history of scoliosis in Zhongshan are identified as a high risk group for scoliosis screening. Developing proper standing and sitting habits helps to reduce the risk of AIS in adolescents.

Postural habits and lifestyle factors associated with adolescent idiopathic scoliosis (AIS) in China: results from a big case-control study.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is the most prevalent type of scoliosis affecting children between the ages of 10-16 years. However, risk factors for AIS, particularly the modifiable ones, are still largely unknown. This study aims to investigate the associations of lifestyle and social environment factors with AIS in Chinese schoolchildren. METHODS: This is a matched case-control study based on survey data collected from school-based scoliosis screening program. We used conditional logistic regression models to describe the relative risk of AIS incidence for each variable in the analyses. To examine the independent effect of each factor on developing AIS, a multivariate conditional logistic regression was conducted and odds ratios (ORs) were adjusted for age and other significant variables. RESULTS: Overall, 2538 participants from 49 schools were included in this study, comprising 1269 AIS cases and 1269 controls. Mean age of the study population was 13.4 years ± 1.06 (range 10-18). One thousand five hundred and fifty (61.1%) of the study subjects were girls. After adjusting for other significant factors, inappropriate desk heights, either too low (OR = 1.40, 95% CI 1.04-1.90) or too high (OR = 1.61, 95% CI 1.09-2.38), standing with anterior pelvic tilt (OR = 2.73, 95% CI 1.41-5.28), and sleeping on the right side (OR = 1.38, 95% CI 1.00-1.91), remained associated with elevated AIS risks. In contrast, sitting normally and classroom sitting positions change regularly were associated with lower odds of AIS. The adjusted ORs were 0.69 (95% CI 0.50-0.96) for sitting normally, and 0.72 (95% CI 0.53-0.98) for sitting positions change. CONCLUSIONS: This is the first study to address the associations between desk heights and AIS and showed inappropriate desk heights were related to increased AIS risks. To protect school children from developing AIS, stakeholders are advised to consider introducing height-adjustable desks in the class, changing students' sitting positions in the classroom on a regular basis, and implementing educational programs to help students maintain correct sitting postures.

Change of weight status during school age and its association with late adolescent blood pressure: Results from a 15-year longitudinal study in China.

Background: Change in obesity risk could be related to shift in high blood pressure (HBP) risk, while individualized influence of weight change on high blood pressure is in need of exploration. Methods: A total of 16,446 children (53.47% boys) and 13,9021 effective annual measurements from 2006 to 2020 were recruited. Children's weight status, both at baseline and endpoint, was categorized as underweight, normal, overweight, and obese according to the age and sex-specific Body Mass Index z scores. HBP at late adolescence was defined with the last two measurements for each child. Populational attributable risk (PAR) of weight trait on HBP risk was calculated. Results: Compared to children who maintained normal weight during follow-up, staying obese was associated with the highest HBP risk with OR of 6.39 (95% CI: 4.46, 9.15; p < 0.001) and PAR of 28.71% (95% CI: 21.58, 35.54) in boys, and OR of 6.12 (95% CI: 2.80, 13.37; p < 0.001) and PAR of 12.75% (95% CI: 4.29, 21.02) in girls. Returning from obese to normal weight was associated with lowered HBP risk, with ORs of 1.07 (95% CI: 0.69, 1.66; p = 0.771) in boys and 0.73 (95% CI: 0.25, 2.12; p = 0.566) in girls. Conclusion: Weight loss program could be effective to reduce HBP risk during school age, while the underlying mechanism needs further exploration.

Prepubertal BMI, pubertal growth patterns, and long-term BMI: Results from a longitudinal analysis in Chinese children and adolescents from 2005 to 2016.

OBJECTIVE: To assess the effects of prepubertal BMI on pubertal growth patterns, and the influence of prepubertal BMI and pubertal growth patterns on long-term BMI among Chinese children and adolescents. METHODS: A total of 9606 individuals aged between 7 and 18 years from longitudinal surveys in Zhongshan city of China from 2005 to 2016 were enrolled. Age at peak height velocity (APHV) and peak height velocity (PHV) were estimated using Super-Imposition by Translation and Rotation (SITAR) model. Associations between prepubertal BMI, APHV, PHV, and long-term overweight and obesity were assessed by linear regression and multinominal logistic regression. Scatter plots were elaborated to show the associations between prepubertal BMI and pubertal growth patterns according to prepubertal BMI categories. RESULTS: Prepubertal BMI Z-Score was positively correlated with long-term BMI Z-Score, and negatively correlated with APHV in both sexes. In addition, there was a negative association between prepubertal BMI Z-Score and PHV in boys. With 1-year decrease in APHV, risk of long-term underweight decreased by 92%, while overweight increased by 33% in boys. Corresponding risk of long-term underweight and overweight for girls decreased by 42% and increased by 20%, respectively. CONCLUSION: High prepubertal BMI levels were associated with earlier APHV and lower PHV, and the early onset of pubertal development could increase the risks of long-term overweight and obesity at 17-18 years of age both in boys and girls. Such evidence emphasized the importance of reducing prepubertal obesity risks combined with appropriate pubertal development timing, including later APHV and higher PHV, so as to prevent the obesity and related cardiovascular diseases in adulthood.

Use of Tri-Ponderal Mass Index in Predicting Late Adolescent Overweight and Obesity in Children Aged 7-18.

Background: Current reference systems using body mass index (BMI) or BMI z-scores to estimate overweight and obesity risk in adolescents are complex to use. An easy and effective measure and cutoffs such as the tri-ponderal mass index (TMI) are in need for parents and grassroots health workers. Objective: The aim of this study was to test whether cohort-derived TMI could be efficient for obesity prediction and to find out whether simplified TMI cutoffs could be used in the prediction. Methods: Data were obtained from a 12-year retrospective growth cohort generated in Guangdong, China. A total of 17,815 children (53.9% were boys) with 151,879 follow-ups conducted annually between 2005 and 2016 were involved. Late adolescent overweight and obesity were defined based on the BMI z-score (WHO 2007 growth reference) of the last measurement, which happened at the mean age of 17.2 (SD: 0.7) for both sexes. Analysis of the area under the curve (AUC) of the receiver operating characteristic curves was used to find the most appropriate cutoff. Results: In total, 9,604 boys and 8,211 girls were included in the final analysis. TMI cutoffs performed better than WHO BMI cutoffs in the prediction of late adolescent overweight and obesity, with all corresponding AUCs <0.7. The simplified TMI cutoffs used to predict late adolescent overweight and obesity were 13.1 and 14.1 kg/m3 for children aged 7 to 15 years, respectively, with the corresponding AUCs ranging from 0.7315 (standard error, SE: 0.0132) to 0.9367 (SE: 0.0052). The cutoffs for predicting late adolescent overweight and obesity for children aged 16 to 18 years were 14.0 and 15.8 kg/m3, respectively, with the corresponding AUCs ranging from 0.9189 (SE: 0.0048) to 0.9841 (95% CI: 0.0027). Conclusion: Tri-ponderal mass index with the ease of administration in practice could be a promising alternative screening tool to BMI for the prediction of late adolescent overweight and obesity.

Could greenness modify the effects of physical activity and air pollutants on overweight and obesity among children and adolescents?

Greenness could theoretically increase the impact of physical activity (PA) and reduce the adverse effects of air pollution on overweight/obesity. However, no evidence systematically compares these two pathways, especially in longitudinal studies of children and adolescent's cohort. Greenness, PA, and air pollution were assessed by Normalized Difference Vegetation Index (NDVI), International Physical Activity Short Form, and 7 pollutants (PM1, PM2.5, PM10, SO2, NO2, CO, and O3). Each exposure was divided into low-/high-level groups based on the 50% quantile. Proportional hazards and logistic regression model were used to assess the associations of greenness, PA, pollutants with overweight/obesity. The incidence of overweight/obesity was 1.98% in the national survey, and the cumulative incidence and incidence density were 12.76% and 3.43 per 100 person-year in the dynamic cohort, separately. An increase of 0.1 units in NDVI was associated with a 12% lower risk of overweight/obesity, but no significant link between PA and incidence was observed. The HRs of the high-level of PM1, PM2.5, PM10, SO2, NO2, CO, and O3 on the risk of overweight/obesity were 2.21, 2.63, 1.88, 2.38, 1.33, 2.43, and 1.33 in the low-level of greenness, which was higher than those in the high-level of greenness. The AFs of PM1, PM2.5, PM10, SO2, NO2, CO, and O3 were 25.58%, 44.37%, 22.96%, 29.15%, 11.55%, 29.50%, and 10.92% in the low-level of greenness, which simultaneously was higher than those in the high-level of greenness. Moreover, the risk of overweight/obesity associated with high-level of greenness in the high-level of PM10, SO2, CO were 0.83, 0.81, and 0.83 respectively. Our findings confirmed that greenness has a moderating effect on the effects of air pollutants on childhood overweight/obesity especially in heavy-industry areas where PM10, SO2, and CO are the major pollutants, although it did not influence the association between PA and overweight/obesity risks.

Exploring Overweight Risk Trajectories During Childhood and Their Associations With Elevated Blood Pressure at Late Adolescence: a Retrospective Cohort Study.

BACKGROUND: Overweight during childhood is significantly associated with higher risk of high blood pressure (HBP) in later life. However, recognition of critical intervention period is limited. We aimed to analyze the changes in overweight risk during school-age and its relationship with HBP. METHODS: Seventeen thousand eight hundred sixteen school-aged children (53.9% boys) with a mean follow-up time of 8.2 years were involved. Children's overweight was defined as body mass index Z score ≥1 and was fitted with a group-based trajectory model. The 4 trajectories were labeled as constant low, high decreasing, low rising, and constant high according to the change of overweight risk during follow-up. Population-averaged logit model and log-binomial regression models were used to analyze HBP risk. Cox proportional hazard model was used to analyze the HBP incidence among distinct groups. RESULTS: Children with higher overweight risk generally had higher HBP risk during follow-up. However, the HBP risk in low rising group was low at baseline and increased to 3.14 (95% CI, 2.54-3.88; P<0.001) for boys and 3.23 (95% CI, 2.08-5.01; P=0.004) for girls at end point, which were comparable to the relative risk in the constant high group (4.60 [95% CI, 4.02-5.27] for boys and 5.28 [95% CI, 3.94-7.07] for girls). CONCLUSIONS: Findings of this study provide insights on patterns of overweight risks during childhood. Children with transition from normal to overweight during teen years would be high-risk in HBP incidence.

Greenness alleviates the effects of ambient particulate matter on the risks of high blood pressure in children and adolescents.

Both ambient particulate matter (PM) and decrease of greenness have been suggested as risk factors for high blood pressure (HBP) in children and adolescents. But most evidence were from cross-sectional studies with limited data from prospective cohorts. In this cohort study, we included 588,004 children and adolescents aged 7 to 18 years without HBP from 2005 to 2018 in Beijing (240,081) and Zhongshan (347,923) city of China. The cumulative incidence of HBP was 32.04%, and incidence rate was 14.86 per 100 person-year. After adjustment for confounders, the ten-unit increase in PM1, PM2.5, and PM10 exposure was significantly associated with 43%, 70%, and 43%- higher risks of HBP, respectively, but the 0.1-unit increase in NDVI exposure was significantly associated with a 25% lower risk of HBP. The HRs of PM1 on the HBP risk were 1.486 and 1.150 in the low and the high-level of greenness, and they were 2.635 and 2.507 for PM2.5, and for PM10 1.367 and 1.702 in the two groups. The attributable fraction (AFs) of PM1, PM2.5, and PM10 on HBP incidents were 13.74%, 40.08%, and 15.47% in the low-level of greenness, which simultaneously was higher than those in the high-level of greenness (AF = 4.62%, 17.28%, and 9.96%). The exposure to higher ambient PM air pollution and lower greenness around schools were associated with a higher risk of HBP in children and adolescents, but higher greenness alleviated the adverse effects of ambient PM1 and PM2.5 on the HBP risks. Our findings highlighted a synergic strategy in preventing childhood HBP by decreasing air pollution reduction and improving greenness concurrently.

The concordance between ultrasonographic stage of breast and Tanner stage of breast for overweight and obese girls: a school population-based study.

OBJECTIVES: In this study, we evaluated the concordance between the ultrasonographic stage of breast (US B) and Tanner stage of breast (TS B) for overweight and obese girls based on a school population study. METHODS: We conducted multistage, stratified cluster, and random-proportional sampling and ultimately included 221 girls (aged 6-10 years). RESULTS: This study revealed that the concordance was poor (accuracy=0.19 (95% confidence interval: 0.14, 0.25)) between US B and TS B among the 221 participants. When our subjects were stratified by weight, we observed a weak association between US B and TS B in the thin/normal weight group (r=0.34, p=0.001) but not in the overweight (r=0.097, p=0.38) or obese groups (r=-0.19, p=0.206), and as the body mass index (BMI) z-score increased, the overestimation ratio of TS B increased. US B manifested a positive correlation with breast bud diameter (BD) (r=0.885, p<0.001), follicle-stimulating hormone (r=0.235, p=0.009), and luteinizing hormone (r=0.192, p=0.037), but this was not the case with TS B. CONCLUSIONS: As the BMI z-score increased, the correlation between the two methods declined, and the overestimation ratio of TS B increased. US B is an objective and quantitative method used to evaluate breast development, and whether BD might replace US B as a routine diagnostic method to evaluate breast development in clinical practice needs to be confirmed in larger-sample studies.

Association of Obesity and Body Fat Percentage with Pubertal State in Six- to Nine-Year-Old Chinese Females.

Background: An early trend in the mean age of pubertal onset appears in adolescents, but the association between body fat percentage (BF%) of children and precocious puberty is unclear. The aim of the study was to analyze the association of sexual development with BF% in girls. Methods: A total of 407 females were included in this cross-sectional study. BF% was measured by Inbody S10, International Obesity Task Force was used to judge overweight or obesity, and early puberty was defined as a younger age than the median age in each of the pubertal Tanner stages. Logistic regression analysis was used to test relationships between pubertal states and independent variables, including age, weight, waist circumference (WC), type of school, and residency. Results: Females with early puberty exhibited higher anthropometry data (such as weight, BMI, BF%) than females with normal maturation (p < 0.001). Weight, BMI, WC, BF% residency, and school type were related to pubertal state (p < 0.001). Females with higher BF% were more likely to exhibit early puberty (odds ratio = 1.138, 95% confidence interval = 1.046-1.237). The students who lived in urban areas and studied in public schools had a lower risk of early puberty. Moreover, BF% continuously increased with age in 6- to 9-year-old girls. Conclusions: Females with higher BF% may be more likely to exhibit early puberty. In future studies, more research is needed to analyze this mechanism of how BF% influences puberty development.

Prevalence of precocious puberty among Chinese children: a school population-based study.

PURPOSE: To investigate the prevalence of precocious puberty in school-based population in Zhongshan, Guangdong, China. METHODS: We recruited a total of 4058 students in grades 1-3 using a multistage stratified cluster random sampling method in a population-based cross-sectional study. We evaluated height, weight, and development of breast and pubic hair in girls, breast development was evaluated by inspection and palpation combined with ultrasound detection for overweight and obese girls, and testicular volume and development of pubic hair in boys. We estimated overall, sex-, age, and district-specific prevalence of precocious puberty and examined the association between prevalence of precocious puberty and body mass index (BMI). RESULTS: The unadjusted and adjusted prevalence of precocious puberty by Tanner stage was 4.74% (girls:8.78%, boys:2.58%) and 6.19% (girls:11.47%, boys:3.26%), respectively. In both urban and suburban areas, the prevalence of precocious puberty was higher in the overweight and obese group than in the normal-weight group (p < 0.05). The prevalence of precocious puberty among overweight (27.94%) and obese (48.00%) girls was higher than that of normal-weight girls (8.73%) (p value for trend < 0.05). In boys, the prevalence of precocious puberty in the obese (6.78%) group was higher than that in the normal-weight (2.86%) group (p < 0.05). CONCLUSIONS: The prevalence of precocious puberty was high in China. Overweight and obesity was related to precocious puberty, but this correlation had gender differences and may be affected by other environmental factors.

Current status and correlates of screen time among children in Guangdong during the COVID-19 pandemic / 中国学校卫生

@#To investigate the current status of online classes, screen time and its influencing factors among primary school students in Guangdong during the 2019 novel coronavirus pandemic.@*Methods@#Using the convenience sampling method, a total of 5 266 pupils aged 6-12-years-old from Guangzhou, Zhanjiang, and Zhongshan participated in the online questionnaire. ANOVA or chi square tests were performed to compare differences in online classes and screen time between grades, and multinomial Logistic regression was performed to analyze the correlates of recreational screen time.@*Results@#The prevalence of prolonged recreational screen time was 42.2% and 55.2% on weekdays and weekends, respectively. Recreational screen time increased by 40.31 min/d on weekdays and 33.07 min/d on weekends, compared to usual school semesters. The average duration of an online class was (26.07±9.62) min, which totaled (110.41±51.98)min per day. Sex, grade, being the only child, and parents education levels were identified as the influencing factors of prolonged recreational screen time. Children who practiced moderate levels (weekdays: OR =1.27; weekends: OR =1.40; P <0.05) or lower levels of physical activity (weekdays: OR =1.86; weekend: OR =1.84; P < 0.05 ) were at a higher risk of prolonged recreational screen time than those who practiced more vigorous physical activity. Children whose parents limited their screen time to a moderate (weekdays: OR=1.61, P <0.05) or lower level (weekdays: OR=1.32, P < 0.05 ) had a higher risk of prolonged recreational screen time than those with a higher frequency. Children with parents recreational screen time ≥ 2 h/d had a higher risk of prolonged recreational screen time than the reference group; children who exhibited moderate to vigorous levels of physical activity <1 h/d (weekdays: OR=1.31, P <0.05), and those used electronic devices for learning 1-2 h/d (weekdays: OR =2.65; weekend: OR =2.65; P <0.05) or for ≥2 h/d (weekdays: OR =4.05, weekend: OR=5.24, P < 0.05 ) were at a higher risk of prolonged recreational screen time than the reference group.@*Conclusion@#During the COVID-19 pandemic, the level of screen time among children in Guangdong was high. Behavioral monitoring and targeted interventions are needed to promote children s health.