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Objective: To investigate the effect of brain derived neurotrophic factor (BDNF) on mesenchymal stem cells (MSC) inhibiting follicular helper T cells (Tfh cells). Methods: The contents of indoleamine 2,3-dioxygenase (IDO), IL-10, TGF-β and IL-21 in MSC culture supernatant were detected by ELISA; The peripheral blood of healthy volunteers were collected, and lymphocyte in peripheral blood was separated by human lymphocyte separation solution; Co-cultures of MSC and lymphocyte were performed by Transwell chamber, and the proportion of CD4(+)CXCR5(+) Tfh cells and their subtypes were detected by flow cytometry. Results: ①The concentrations of IL-10, TGF-β, and IDO in the supernatant of BDNF group (BDNF-stimulated MSC) were higher than those of the control ones (adding PBS with the same volume) [IL-10: (42.1±4.4) ng/ml vs (19.3±2.1) ng/ml, t =4.761, P =0.009; TGF-β: (13.9±1.7) ng/ml vs (5.3±0.6) ng/ml, t =5.129, P =0.008; IDO: (441.3±56.9) ng/ml vs (226.7±37.6) ng/ml, t =3.130, P =0.035]; ②The comparisons between BDNF (co-culture of lymphocyte and BDNF-stimulated MSC) and MSC groups (co-culture of lymphocyte and MSC) were detailed as of follows: the proportion of CD4(+) CXCR5(+)Tfh cells were lower [(3.37±0.21)% vs (6.51±0.27)%, t =9.353, P <0.001], the proportion of CD4(+) CXCR5(+)CXCR3(+) CCR6(-) Tfh cells were higher [(41.14±2.04)% vs (26.72±2.57)%, t =4.383, P =0.012], CD4(+)CXCR5(+)CXCR3(-)CCR6(-) Tfh2 cells and CD4(+)CXCR5(+)CXCR3(-)CCR6(+) Tfh17 cells were lower [Tfh2: (30.16±5.38)% vs (43.26±4.11)%, t =4.426, P =0.012; Tfh17: (15.61±1.52)% vs (22.32±0.72)%, t =4.202, P =0.014], the proportion of CD4(+)CXCR5(+)Foxp3(+) Tfr cells were higher [(4.95±0.22)% vs (2.32±0.16)%, t =10.241, P <0.001], the concentration of IL-21 in the lymphocyte supernatant was lower [(0.28±0.03) ng/ml vs (0.85±0.08) ng/ml, t =6.675, P =0.003]. Conclusion: BDNF could enhance the inhibitory effect of MSC on Tfh cells through inhibiting the increasing of Tfh cells and the differentiations of Tfh2 and Tfh17 cells.

Objective: To investigate the incidence and pathogen distribution of ventilator-associated pneumonia (VAP) among preterm infants admitted to level Ⅲ neonatal intensive care units (NICU) in China. Method: A prospective study was conducted in 25 level Ⅲ NICU, enrolling all preterm infants <34 weeks gestational age admitted to the participating NICU within the first 7 days of life from May 2015 to April 2016. Chi-square test, t test and Mann-Whitney U test were used for statistical analysis. Result: A total of 7 918 patients were enrolled, within whom 4 623(58.4%) were males. The birth weight was (1 639±415) g and the gestational age was (31.4±2.0) weeks; 4 654(58.8%) infants required non-invasive mechanical ventilation and 2 154(27.2%) required intubation. Of all the mechanically ventilated patients, VAP occurred in 95 patients. The overall VAP rate was 7.0 episodes per 1 000 ventilator days, varying from 0 to 34.4 episodes per 1 000 ventilator days in different centers. The incidence of VAP was 9.6 and 6.0 per 1 000 ventilator days in children's hospitals and maternity-infant hospitals respectively, without significant differences ( t =1.002, P =0.327). Gram - negative bacilli (76 strains, 91.6%) were the primary VAP microorganisms, mainly Acinetobacter baumannii (24 strains, 28.9%), Klebsiella pneumonia (23 strains, 27.7%), and Pseudomonas aeruginosa (10 strains, 12.0%). Conclusion: The incidence of VAP in China is similar to that in developed counties, with substantial variability in different NICU settings. More efforts are needed to monitor and evaluate the preventable factors associated with VAP and conduct interventions that could effectively reduce the occurrence of VAP.

The central hypotensive effect of neuropeptide Y (NPY) has been investigated by microinjection of the peptide into substantia nigra (SN) of anesthetized normotensive rats. NPY microinjection into SN produced dose-dependent falls in arterial blood pressure but no change in heart rate statistically. Microinjection of cholecystokinin octapeptide or 0.9% saline into SN did not elicit prominent change in arterial blood pressure and heart rate. The results suggest that NPY in SN exerts a distinctive hypotensive effect in certain degree.

Cardiovascular effects of microinjection of neuropeptide Y (NPY) into the lateral septal nucleus (LS) were investigated in anaesthetized rats. The microinjection gave rise to a significant increase in blood pressure and heart rate. The pressure response was dose-dependent but the tachycardia was not. Control injection of 0.9% saline into LS produced no haemodynamic response.

Cardiovascular effect of norepinephrine (NE) in the habenular nucleus (Hb) and the underlying mechanism were investigated in urethane-anesthetized rats. NE microinjection into Hb produced a dose-dependent increase in mean arterial blood pressure and heart rate, an effect that could be attenuated by the pretreatment in Hb with alpha-receptor blocker phentolamine, but not by the pretreatment with beta-receptor blocker propranolol or physiological saline. Microinjection of kainic acid into Hb gave rise to a marked increase in mean arterial blood pressure and heart rate, but microinjection of lidocaine did not elicit significant cardiovascular effect. The above results suggest that NE in Hb plays an important role in cardiovascular control as a result of Hb excitation through activation of alpha-receptor.

The present study was to determine if the cardiovascular effect being produced by exciting cells in the habenular nucleus (Hab). Experiments were performed on urethane-anesthetized rats. Microinjection of kainic acid into Hab demonstrated dose-dependent increases in arterial blood pressure and heart rate, accompanied by other sympathetic reactions, such as mydriasis and pilo-erection. But microinjection of lidocaine into Hab did not elicit similar effects mentioned above.

The electrical stimulation of the lateral hypothalamic area (LH) in the rat elicited an obvious rise of the arterial pressure and increase in the heart rate. After the microinjection of lidocaine hydrochloride into the habenular nucleus (Hb) on the same side of the electrode, the vasopressor effect elicited by the electrical stimulation of the LH was blocked by 38.9% and the effect on heart rate was reduced by 44.4%. After the microinjection of lidocaine hydrochloride into the bilateral Hb, the vasopressor effect elicited by the electrical stimulation of the LH was blocked by 40.7% and the effect on heart rate was reduced by 41.2%. After the microinjection of the artificial cerebrospinal fluid into the unilateral or bilateral Hb, the cardiovascular effect elicited by the electrical stimulation of the LH was not affected. The electrical stimulation of the Hb in the rat elicited an obvious rise of the arterial pressure, but the heart rate was not changed significantly. After the microinjection of lidocaine hydrochloride into the LH on the same side of the electrode the vasopressor effect elicited by the electrical stimulation of the Hb was blocked by 63.2%. After the microinjection of lidocaine hydrochloride into the bilateral LH the vasopressor effect elicited by the electrical stimulation of Hb was blocked by 62.6%. After the microinjection of the artificial cerebrospinal fluid into the unilateral or bilateral LH, the cardiovascular effect elicited by the electrical stimulation of the Hb was not affected. The present study shows that the Hb and LH exert synergistic action in the regulation of the cardiovascular activities.