MASH1 induces neuron transdifferentiation of adrenal medulla chromaffin cells / 中南大学学报(医学版)

OBJECTIVES@#Nerve growth factor (NGF) induces neuron transdifferentiation of adrenal medulla chromaffin cells (AMCCs) and consequently downregulates the secretion of epinephrine (EPI), which may be involved in the pathogenesis of bronchial asthma. Mammalian achaete scute-homologous 1 (MASH1), a key regulator of neurogenesis in the nervous system, has been proved to be elevated in AMCCs with neuron transdifferentiation in vivo. This study aims to explore the role of MASH1 in the process of neuron transdifferentiation of AMCCs and the mechanisms.@*METHODS@#Rat AMCCs were isolated and cultured. AMCCs were transfected with siMASH1 or MASH1 overexpression plasmid, then were stimulated with NGF and/or dexamethasone, PD98059 (a MAPK kinase-1 inhibitor) for 48 hours. Morphological changes were observed using light and electron microscope. Phenylethanolamine-N-methyltransferase (PNMT, the key enzyme for epinephrine synthesis) and tyrosine hydroxylase were detected by immunofluorescence. Western blotting was used to test the protein levels of PNMT, MASH1, peripherin (neuronal markers), extracellular regulated protein kinases (ERK), phosphorylated extracellular regulated protein kinases (pERK), and JMJD3. Real-time RT-PCR was applied to analyze the mRNA levels of MASH1 and JMJD3. EPI levels in the cellular supernatant were measured using ELISA.@*RESULTS@#Cells with both tyrosine hydroxylase and PNMT positive by immunofluorescence were proved to be AMCCs. Exposure to NGF, AMCCs exhibited neurite-like processes concomitant with increases in pERK/ERK, peripherin, and MASH1 levels (all P<0.05). Additionally, impairment of endocrine phenotype was proved by a signifcant decrease in the PNMT level and the secretion of EPI from AMCCs (all P<0.01). MASH1 interference reversed the effect of NGF, causing increases in the levels of PNMT and EPI, conversely reduced the peripherin level and cell processes (all P<0.01). MASH1 overexpression significantly increased the number of cell processes and peripherin level, while decreased the levels of PNMT and EPI (all P<0.01). Compared with the NGF group, the levels of MASH1, JMJD3 protein and mRNA in AMCCs in the NGF+PD98059 group were decreased (all P<0.05). After treatment with PD98059 and dexamethasone, the effect of NGF on promoting the transdifferentiation of AMCCs was inhibited, and the number of cell processes and EPI levels were decreased (both P<0.05). In addition, the activity of the pERK/MASH1 pathway activated by NGF was also inhibited.@*CONCLUSIONS@#MASH1 is the key factor in neuron transdifferentiation of AMCCs. NGF-induced neuron transdifferentiation is probably mediated via pERK/MASH1 signaling.

Research advances of debriefing methods in scenario stimulation teaching / 中华医学教育探索杂志

Based on the latest results of international researches, combining with the experiences of our team in the simulation of acute dyspnea, Xiangya Hospital Central South University has summarized 7 characteristics, procedures and methods of debriefing, including that immediate feedback happens after simulation; feedback is provided by a trained instructor with clinical experience; feedback time is at least longer than the simulation time; various international methods of feedback can be used; the content of feedback is the learning objective; oral feedback is preferred; video can be used to review the details. The study aims to provide a theoretical basis for debriefing in domestic scenario stimulation teaching, and finally improve the effectiveness of the scenario stimulation teaching.

Clinical comparative analysis for pulmonary histoplasmosis and progressive disseminated histoplasmosis / 中南大学学报(医学版)

To compare clinical features, diagnosis and therapeutic effect between pulmonary histoplasmosis and progressive disseminated histoplasmosis.
 Methods: A retrospective analysis for 12 cases of hospitalized patients with histoplasmosis, who was admitted in Xiangya Hospital, Central South University during the time from February 2009 to October 2015, was carried out. Four cases of pulmonary histoplasmosis and 8 cases of progressive disseminated histoplasmosis were included. The differences of clinical features, imaging tests, means for diagnosis and prognosis were analyzed between the two types of histoplasmosis.
 Results: The clinical manifestations of pulmonary histoplasmosis were mild, such as dry cough. However, the main clinical symptoms of progressive disseminated histoplasmosis were severe, including recurrence of high fever, superficial lymph node enlargement over the whole body, hepatosplenomegaly, accompanied by cough, abdominal pain, joint pain, skin changes, etc.Laboratory examination showed pancytopenia, abnormal liver function and abnormal coagulation function. One pulmonary case received the operation of left lower lung lobectomy, 3 cases of pulmonary histoplasmosis and 6 cases of progressive disseminated histoplasmosis patients were given deoxycholate amphotericin B, itraconazole, voriconazole or fluconazole for antifungal therapy. One disseminated case discharged from the hospital without treatment after diagnosis of histoplasmosis, and 1 disseminated case combined with severe pneumonia and active tuberculosis died ultimately.
 Conclusion: As a rare fungal infection, histoplasmosis is easily to be misdiagnosed. The diagnostic criteria depends on etiology through bone marrow smear and tissues biopsy. Liposomeal amphotericin B, deoxycholate amphotericin B and itraconazole are recommended to treat infection for histoplasma capsulatum.

Endarterium injury and the related pathway in chronic intermittent hypoxia rats / 中南大学学报(医学版)

Objective:To examine the pathological change and intima thickness of thoracic aorta, detect the serum concentration of hypoxia-inducible factor-1α(HIF-1α), oxidized LDL (ox-LDL), and pentraxin 3 (PTX3) in the rat model of chronic intermittent hypoxia (CIH), and to determine the effect of CIH on endarterium injury and its possible pathway.Methods:Twenty-four male Sprague-Dawley (SD) rats were divided into 4 groups:a CIH+N-acetylcysteine (NAC) group, a CIH+normal saline (NS) group, a CIH control group and a control group. CIH rats were subjected to alternating cycles of hypoxia (6%-8%O2 in N2 for 20-25 s) and normoxia (21%O2 in N2 for 2 min) every 180 s for 7 h/d. Rats in the control group were not treated. Rats in the CIH+NAC group were treated with NAC [800 mL/(kg.d)] intraperitoneal injection, and rats in the CIH+NS group were treated with NS [5 mL/(kg.d)] intraperitoneal injection. Atfer 42 day treatment, the rats were sacriifced, blood taken, and thoracic aorta cut off. hTe serum concentration of HIF-1α, ox-LDL, and PTX3 were detected by ELISA. hTe thickness of intima was taken by computer digital image analysis. Results:Vascular endothelial cell injury and detachment were found in the thoracic aorta in the CIH and the CIH+NS group. The intima in the CIH and the CIH+NS group was thicker than that in the control and the CIH+NAC group (P<0.001). The serum concentration of HIF-1α, ox-LDL, and PTX3 in the CIH and the CIH+NS group was higher than that in the control and the CIH+NAC group (P<0.001). The serum concentration of HIF-1α, ox-LDL, and PTX3 was pairwise positive correlation, and the serum concentration of ox-LDL and PTX3 was positively correlated with the thickness of intina (P<0.001). Conclusion:hTe vascular endothelial cell injury and endarterium thickening can be induced by CIH. It is an important pathway that CIH activates oxidative stress and elevates the levels of HIF-1α, ox-LDL, and PTX3.

Mechanisms of sympathetic activity in rats exposed to different patterns of hypoxia and the correlation with blood pressure / 中南大学学报(医学版)

OBJECTIVE@#To observe the effects of two different hypoxia patterns on blood pressure and the underlying mechanisms.@*METHODS@#Eighteen male SD rats were randomly divided into three groups: the intermittent hypoxia group (IH group), the continuous hypoxia group (CH group) and the normal control group (NC group). The rats of the IH and CH group were subjected to intermittent hypoxia (7 h/d) and continuous hypoxia (7 h/d) for 42 days respectively. The NC group rats were untreated. The levels of arteria caudilis systolic pressure (ACSP) were measured with noninvasive rats arteria caudilis gauge before the experiment, at the end of 3rd, 6th week of the experiment. The concentrations of norepinephrine (NE) in serum and neuropeptide Y (NPY) in plasma were respectively measured by enzyme-linked-immunosorbent assay (ELISA) and radioimmunoassay. The contents of malondialdehyde (MDA) and the ability of inhibiting hydroxyl free radical in serum were analyzed by thiobarbituric acid colorimetric analysis (TBAR) at the end of 6th week.@*RESULTS@#At the end of 3rd week, the levels of ACSP were considerably higher than those before the treatment (P0.05). The levels of NE, NPY and MDA were positively related with ACSP (r=0.873, P<0.01; r=0.671, P<0.01; r=0.582, P<0.05). The correlation between the ability of inhibiting hydroxyl free radical and ACSP was negative (r=-0.790, P<0.01). the concentrations of MDA were positively related with NE and NPY respectively (r=0.843, 0.777, P<0.01) and the ability of inhibiting hydroxyl free radical was negatively related with NE and NPY respectively (r=-0.864, -0.717, P<0.01).@*CONCLUSION@#Intermittent hypoxia can induce high blood pressure, which may be related to the sympathetic over-activity and the oxidative stress.