The prevalence of childhood asthma has been increased yearly.Based on the hygiene hypothesis,the antibiotic use may increase the risk of the allergic disease by reducing microbial exposure.In the last decade,a number of epidemiological studies have been conducted on the association between early exposure of antibiotic and childhood asthma,and the results are not consistent.The majority retrospective studies have found a positive association but the prospective studies have showed a null or weak association.Reverse causation and confounding-by-indication may partly explain the relation.But it is difficult to deny a causal link between antibiotic use and asthma.

According to clinical epidemiological researches, the usage of antibiotics in infant increases the risk of childhood asthma morbidity. The mechanism of this link is not entirely clariifed, and it is assumed of being related to side effects of antibiotics, which changes the colonization of normal intestinal lfora and reduces the diversity. It is clear that normal intestinal lfora of infant help to construct innate immune system and adaptive immune system, and forge immune tolerance. Therefore, normal intestinal lfora might be helpful in reducing allergies. The usage of antibiotics in early life changes the quantity and the composition of intestinal lfora, and breaks the balance of immune homeostasis, which might increase the risk of asthma morbidity. The abuse of antibiotics in children is a general phenomenon in China which needs attention from pediatricians.

Objective To identify the dynamic influence of antibiotics use on T helper cell(Th) 1/Th2 cytokine balance in neonatal rats in their early life.Methods Twenty-four newborn SD rats were randomly divided into 3 groups including 2dCef group,7dCef group and a control group (n =8).SD rats at 2 or 7 days of age were injected Cefotaxime sodium intraperitoneally for 3 consecutive days.The control group was injected the same amount of phosphate buffer saline.Serum and bronchoaveolar lavage fluid (BALF) samples were collected on 35 days old and diffe-rential cell count in BALF was done.Enzyme linked immunosorbent was used to detect the concentration of interleukin(IL)-12,interferon-γ(IFN-γ),IL-4 and IL-5 in serum and BALF,and real-time quantitative PCR was used to detect mRNA expression of those cytokines in lung tissues.Results The number of total cells,neutrophils,and lymphocytes in Cefotaxime treated on 2nd day after birth were significantly higher than those in the controls and 7th day group (F =93.78,15.84,7.36,all P ＜0.05).For Thl cytokines detection:the IL-12 secretion in BALF and serum and INF -γsecretion in BALF of the 2 antibiotic groups were lower than those in control group (F =26.53,12.95,47.18,all P ＜ 0.05),the decrease in 2dCef group were more obviously than 7dCef group [(127.72 ± 12.35) ng/L vs (198.15 ± 18.93) ng/L,(105.91±13.61) ng/Lvs (133.63 ±13.82) ng/L,(147.23 ±24.10) ng/Lvs (178.52±12.46) ng/L,all P ＜0.05].The mRNA expression of IL-12 in antibiotic groups were lower than those in control group (F =33.60,P ＜0.05),and the decrease in 2dCef group was more obvious than that in 7 dCef group (0.073 ± 0.023 vs 0.093 ± 0.028,P ＜0.05).For the Th2 cytokines:the IL-4 secretion concentration and mRNA expression in the 2 antibiotic groups were higher than those in the control group (BALF,serum and lung) (F =64.26,13.79,11.54,all P ＜ 0.05),the increase in 2dCef group was more obvious than that in 7dCef group[(103.65 ± 7.68) ng/L vs (82.04 ± 8.77) ng/L,(87.81 ± 4.72) ng/L vs (69.69 ± 7.79) ng/L,(0.067 ± 0.036) ng/L vs (0.051 ± 0.055),all P ＜ 0.05];however,no significant differences of IL-5 either mRNA or cytokine secretion being detected among these 3 groups (F =0.50,0.75,0.08,all P ＞ 0.05).Conclusions Antibiotic use during early time of neonate rats alters postnatal immune cells distribution in the lung and promotes the shift in cytokine balance towards a Th2 profile,and the earlier the antibiotic use,the more serious the impact.

Objective To investigate the related factors of central regional lymph node metastasis (CLNM) in patients with papillary thyroid microcarcinoma (PTMC).Methods The clinical and pathological fea tures of 550 cases of PTMC with clinical lymph node negative (cN0) were retrospectively analyzed.x2 test and multivariate logistic regression analysis were used to analyze the related factors of CLNM.ROC curve was used to analyze tumor diameter and CLNM of PTMC.Results The CLNM rate was 35.6％.Univariate analysis showed that patients aging less than 45 y(x2=13.983,P＜0.001),with tumor diameter≥7 mm (x2=14.263,P＜0.001),with capsule invasion (x2=7.316,P=0.006),multifocality (x2=14.321,P＜0.05) and bilateral tumors (x2=9.265,P=0.002) were more likely to have CLNM.Multivariate Logistic regression analysis showed that age ＜45 y,tumor diameter ≥7 mm,invasion of capsule and multifocal are all independent risk factors of CLNM for patients with PTMC.The optimal cutoff value of CLNM by diameter was 8 mm.Conclusion The CLNM of PTMC is related to many factors.When the age of the patient is less than 45 y,the diameter of the tumor is more than 7 mm,the invasion of the capsule and the multifocal lesion,the central lymph node dissection should be performed.