[Association of vitamin D nutritional status with calcaneal bone mineral density in school-age children: a prospective cohort study].

Objective: To investigate the relationships between vitamin D nutritional status and the calcaneal bone mineral density (BMD) in children. Methods: Data were obtained from School-based Cardiovascular and Bone Health Promotion Program. In 2017, a total of 15 391 children aged 6-16 years in Beijing selected through stratified cluster sampling were included in the baseline survey. A follow-up investigation was conducted in 2019. The questionnaire survey, detection of serum 25-hydroxyvitamin D [25(OH)D] level and ultrasound measurement of calcaneal BMD were conducted. Multivariable linear and logistic regression models were used to analyze the relationships between baseline vitamin D nutritional status and the follow-up calcaneal BMD. Results: A total of 10 914 children aged (11.5±3.3) years (boys accounting for 49.6%) were included in the analysis. The average 25(OH)D level was (35.4±12.0) nmol/L, and the deficiency rate was 36.1%. After the adjustment for age, gender, body mass index, smoking status, alcohol use status, dairy products intake, vitamin D supplement, calcium supplement, physical activity, pubertal development, and baseline calcaneal BMD Z-score, for per 10 nmol/L increase in 25(OH)D, the follow-up calcaneal BMD Z-score increased by 0.01(P=0.041), and the OR(95%CI) of decreased calcaneal BMD Z-score after 2 years was 0.96 (0.93-1.00)(P=0.030). Compared with vitamin D adequacy, the follow-up calcaneal BMD Z-score of children with vitamin D insufficiency and deficiency decreased by 0.03(P=0.307) and 0.06 (P=0.046), and the risk of decreased calcaneal BMD Z-score after 2 years increased by 15%(P=0.037) and 21%(P=0.006), respectively (P for trend<0.05). Conclusions: Vitamin D nutritional status was closely related to calcaneal BMD, and children with adequate vitamin D nutritional status tended to obtain higher BMD. Children and adolescents are encouraged to maintain sufficient vitamin D levels, strengthen nutrition and exercise to promote bone health.

[Association of vitamin D nutritional status with body muscle mass in school-age children adolescents].

Objective: To investigate the association between vitamin D nutritional status and the body muscle mass in children. Methods: Data were obtained from School-based Cardiovascular and Bone Health Promotion Program. In 2017, a total of 15 391 children aged 6-16 years in Beijing were selected through stratified cluster sampling in baseline survey. A follow-up investigation was conducted in 2019. The questionnaire survey and the detection of serum 25-hydroxyvitamin D [25(OH)D] level were conducted. The bioelectrical impedance analysis (BIA) apparatus was used to measure body muscle mass, and muscle mass index (MMI) was calculated. Multivariable linear models were used to analyze the association of vitamin D nutritional status with the baseline and follow-up MMI measures. Results: A total of 10 890 children aged (11.5±3.3) years(boys accounting for 49.6%) were included in the analysis. The average 25(OH)D level was (35.4±12.0) nmol/L, with an adequacy ratio of 11.1%. After multivariate linear regression adjustment for age, sex, body fat mass, smoking status, alcohol use status, dairy supplement, calcium supplement, physical activity, and pubertal development, no statistically significant association between vitamin D nutritional status and baseline MMI level was observed (P>0.05). For the follow-up MMI, the Z-score increased by 0.008 (P=0.058) for per 10 nmol/L increase in 25(OH)D, which were 0.002 (P=0.815) and 0.037 (P=0.031) higher in children with insufficient and adequate vitamin D than those with vitamin D deficiency, respectively (P for trend =0.089). Subgroup analysis showed that in the normal BMI group, for per 10 nmol/L increase in 25 (OH) D, the MMI at baseline survey and MMI Z-score at follow-up of children with adequate vitamin D and increased by 0.019 and 0.014, respectively (both P<0.05). Conclusions: Vitamin D nutritional status was related to muscle mass in children, and children with adequate vitamin D tended to obtain higher MMI. Children and adolescents are encouraged to maintain sufficient vitamin D levels, strengthen nutrition and exercise to promote body health.

[The association between body fat distribution and calcaneal bone mineral density in children and adolescents aged 6-16 years in Beijing].

Objective: To understand the association between body fat distribution and calcaneal bone mineral density (BMD) in children and adolescents aged 6-16 years in Beijing. Methods: Children and adolescents were selected in 30 schools (8 primary schools, 21 middle schools and one 12-year education school) from Dongcheng, Tongzhou, Fangshan and Miyun districts of Beijing by using a stratified cluster sampling method from November 2017 to January 2018. A total of 15 030 students in grade 1 to 4 of primary school, grade 1 of junior and senior middle school were enrolled after excluding subjects who were not able to participate into this study due to trauma or other uncomfortable physical conditions or with missing key values or with diabetes and kidney diseases. Questionnaire survey, body composition and calcaneus bone mineral density were conducted. The relation of fat mass percentage (FMP), trunk to total fat ratio (TrTFR), trunk to limb fat ratio (TrLFR), limb to total fat ratio (LTFR) and viscera to total fat ratio (VTFR) with calcaneus BMD were assessed using the multivariate linear regression models after adjusting for possible confounding effects. The central fat distribution types were divided into 4 groups including type 1: both trunk fat and visceral fat greater than the sex-and age-specific internal P(75); type 2: barely trunk fat greater than P(75); type 3: barely visceral fat greater than P(75); type 4: both trunk fat and visceral fat greater than P(75). The central fat distribution types were included into the model in the form of dummy variables to analyze its relationship with calcaneal BMD. The sex-and age-specific z-scores of fat distribution indicators and BMD were calculated. Results: A total of 15 030 participants aged (11.4±3.3) years (50.2% boys) were involved in the analysis. In both genders, after adjusting for age, height, lean mass index, smoking, drinking, physical activity, milk intake, vitamin D and calcium supplementation, FMP, TrTFR, TrLFR and VTFR were negatively correlated with calcaneal BMD (all P value<0.05), while LTFR was positively associated with calcaneal BMD (all P values<0.05). Compared to the central fat distribution type 1, the regression coefficients (95% CI) of type 2, 3 and 4 were -0.253 (-0.418, -0.087), -0.385 (-0.567, -0.204) and -0.428 (-0.487, -0.369) in boys, respectively; the regression coefficients (95% CI) of type 3 and 4 were -0.158 (-0.301, -0.015) and -0.226 (-0.290, -0.163), respectively. Conclusion: Body fat distribution and central fat distribution in children and adolescents were correlated with calcaneus bone mineral density.

[The association between blood lipids and calcaneus bone mineral density in children and adolescents aged 6-16 years in Beijing].

Objective: To investigate the association between blood lipid and calcaneus bone mineral density (BMD) in children and adolescents aged 6-16 years in Beijing. Methods: Children and adolescents were selected in 30 schools (8 primary schools, 21 middle schools and one 12-year education school) from Dongcheng, Tongzhou, Fangshan and Miyun districts of Beijing by using a stratified cluster sampling method from November 2017 to January 2018. A total of 14 303 students in grade 1 to 4 of primary school, grade 1 of junior and senior middle school were enrolled after excluding subjects who were not able to participate into this study due to trauma or other uncomfortable physical conditions or with missing key values or with diabetes and kidney diseases. Questionnaire survey, blood lipid and calcaneus BMD were conducted. Multivariate linear regression was applied to quantify the association between calcaneal BMD as a dependent variable and blood lipid level as an independent variable after adjusting for the potential confounding factors. Furthermore, quantile regression was used to analyze the association between blood lipid level and different percentiles (P(25), P(50) and P(75)) of ultrasonic velocity values of bone mineral density, and parallel test was conducted for regression coefficients of different percentiles. Results: A total of 14 303 participants aged (11.4±3.3) years (49.9% boys) were involved in the analysis. The mean age of 14 303 participants was (11.0±3.3) years. 7 142 boys accounted for 49.9%. The mean±SD of calcaneal BMD, total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), and high density lipoprotein-cholesterol (HDL-C) were (1 540.9±33.8) m/s, (3.90±0.76), (2.18±0.62), and (1.40±0.32) mmol/L, respectively. The P(5)0 (P(25), P(75)) of triglyceride (TG) was 0.69 (0.49-0.94) mmol/L. After the adjustment of age, height, smoking, drinking, vitamin D and calcium supplementation, dairy intake, physical activity, FMI, and MMI, a significantly inverse association (P<0.05) between TG level and calcaneus BMD was observed in both genders, which the regression coefficients (95%CI) in boys and girls were -0.064 (-0.085, -0.044) and -0.073 (-0.094, -0.053), respectively. Conclusion: The level of BMD was associated with TG in boys and girls. Therefore, it is important to prevent children from hypertriglyceridemia for the bone health promotion.

Studies on the phenomenon of latent propagated sensation along the channels. I. The discovery of a latent PSC and a preliminary study of its skin electrical conductance.

By combining electrical impulse stimuli with mechanical ones, we are able to trace out a new line of feeling, coincident with the classical channel course. Impulse stimulation was carried out at the Jing point of the Large Intestine or Stomach channel, namely Shangyan or Lidui. With a small rubber nipple, light taps were applied on the skin along the lines perpendicular to the channel and crossing over the acupuncture points; a specific propagational numb feeling at the points of the channel could be found. By linking up these points of specific feeling, an imaginary line which is exactly the classical Large Intestine or Stomach channel can be traced out. This line is called the "latent propagational sensation line along the channels" because, unless through tapping, no prominent sensation of propagation could be felt. Employing an impulsive electrical generator and an all-wave commutating circuit linked to a micro-ammeter, the skin conductance was measured over the latent PSC of the Large Intestine channel lying between the wrist and 5 cm above the elbow joint. Results were compared to those locations of 1 cm apart from the channel course, i.e. the control sites devoid of acupuncture points or channels. At most acupuncture points or any site of the channel course on all of the 10 subjects under examination, there was greater electrical conductance maxima than there was at control sites. This fact indicates that not only the acupuncture points, but the entire course of latent PSC are also of higher electrical conductance.

Studies on the phenomenon of latent propagated sensation along the channels. II. Investigation on the lines of LPSC on the twelve main channels.

Applying an electric impulse at the Jing points and then tapping on the skin surface along the lines perpendicular to the channels, latent PSC of 12 channels was examined respectively on 200 patients at an acupuncture clinic. Of the cases examined, 68.5% were found to have positive latent PSC. No prominent difference was found among the 12 main channels. In patients with higher sensitivity of latent PSC and in those with marked PSC as well, the traces of latent PSC can be located simply by tapping (i.e. without electric impulsation at the Jing points), and the width of the sensitive lines is about 0.5 cm. Furthermore, in cases with marked PSC, the latent sensation lines were always found to be a continuation of the marked ones. These facts indicate that the latent PSC is a common meridian phenomenon in a large number of individuals.