Objective: To investigate the effect of biology and mTOR pathway activity of down-regulated TSC2 gene expression on U937 leukemia cells. Methods: Gene expression was down-regulated by lentivirus induced RNA interference on TSC2 high expressed U937 cell line; the proliferation, apoptosis and differentiation were detected by CCK-8 assay, colony formation assay and flow cytometry; the gene expression level and protein kinase activity were detected by qRT-PCR and Western blot. Results: Down-regulated expression of TSC2 gene promoted U937 cell proliferation and colony formation ability (P<0.05) . The proportion in G₀/G₁ phase of TSC2 down-regulated U937 cell was much lower than that of the control cells [ (52.53±3.75) % vs (75.10±4.33) %, t=6.829, P=0.002], the S phase [ (22.43±1.00) % vs (15.47±1.20) %, t=-5.581, P=0.019] and G₂/M phase [ (25.03±4.34) % vs (14.33±0.91) %, t=-5.413, P=0.013] was remarkably higher than that of the control cells (P<0.05) . There were no statistically significant differences in cell apoptosis and differentiation (P>0.05) . Down-regulation of TSC2 led to the increased activity of mTOR, 4EBP1 and S6K1, but did not influence the activity of AKT. The expressions of proliferation related cyclinD1, c-myc and PTEN were also up-regulated after TSC2 silenced, but the expressions of P27KIP and BCL-XL were not changed. Conclusion Downregulation of TSC2 could promote the proliferation of U937 cells through up-regulation of mTOR activity.

Objective:To analyze the current situation of the mothers and infants at their first visit to the breastfeeding counseling clinic, and provide a reference for promoting breastfeeding in infancy.Methods:Clinical data of 581 mother-infant-dyads visiting the breastfeeding counseling clinic of Nanjing Maternal and Child Health Hospital from January 2019 to December 2019 were collected and analyzed retrospectively, including the general information of the dyads, and the subjective and actual reasons for visits. According to the age of infants coming to the clinics, they are divided into the younger group (60 d and below, n=316), middle-aged group (61-120 d, n=178), and older group (121 d and above, n=87). Differences in exclusive breastfeeding rate and reasons for visits between different groups were analyzed by analysis of variance, Kruskal-Wallis rank sum test, Chi-square test, or Fisher's exact test. Results:The age of the 581 infants at the first visit were mainly at 30-34, 41-45 and 90-94 d, which accounted for 9.3%( n=54), 25.3%( n=147), and 9.0%( n=52), respectively. The total exclusive breastfeeding rate was 71.8%( n=417) at visit, and there were significant differences among the younger, middle-aged and older group [67.7%(214/316), 79.8%(142/178), 70.1%(61/87), χ 2=14.294, P=0.006), and between the younger and middle-aged group in the pairwise comparison. The most common subjective reason for visiting was slow weight gain ( n=249, 42.9%), followed by worrying about insufficient milk ( n=142, 24.4%) and feeding difficulties ( n=132, 22.7%). Whereas the top three practical reasons for visiting included infant's inability to latch on or sucking ( n=165, 28.4%), lack of breastfeeding knowledge ( n=149, 25.6%) and inappropriate maternal feeding skills ( n=140, 24.1%). The younger group faced more problems regarding latching on or sucking [39.6%(125/316] and mother's feeding skills[25.9%(82/316)], while the lack of breastfeeding knowledge mainly occurred in the older group[48.3%(42/87)]. The coincidence rates between the subjective and actual reasons for slow weight gain, worrying of insufficient milk, and feeding difficulties were only 1.2%( n=3), 6.3%( n=11), and 21.2%( n=28). Conclusions:Breastfeeding- related problems exist in infants of different ages below one year old. There is a big knowledge gap between the subjective reasons for medical visits and the actual problems that interfere with breastfeeding. Therefore, individualized breastfeeding guidance for infants of different ages is recommended in children's health clinics.