BACKGROUND: The rare earth elements (Res) have multiple bio-activities and some extent neurotoxicity, Because of their distinct physical and chemical properties. The studies on neuromuscular junction and sympathet ic ganglia have shown that some Res, such as lanthanum(La), gadolinium (Gd),etc, exert considerable effects on synaptic transmission, but the effects and mechanism of Samarium on synaptic transmission are still unknown.OBJECTIVE: To investigate the effects and impossible mechanism of Samarium Chloride (SmCl3) on the nicotinic transmission in the isolated sympathetic ganglia, superior cervical ganglion (SCG) of rats.DESIGN: Controlled experimental study based on cells.SETTING: Department of Pharmacology, Guangxi Medical University. MATERIALS: Totally 40 adult Wistar rats (weighing 250-300 g) of either sex, provided by the Experimental Animal Center of Guangxi Medical University, were used in this study. SmCl3 was made by the chlorination of Samarium Oxide with purity 99.5% and relative molecule mass 348.7, presented by Professor Liu Da-yuan, Guangxi Medical University. Acetylcholine chloride (Ach) and carbachol (Carb) were purchased from Sigma.METHODS: The experiment was completed at the neuropharmacology lab of the experimental center of Guangxi Medical University from September 2001 to December 2002. After sacrificing animals by acute exsanguination,SCG together with their preganglionic nerve trunks were isolated rapidly,then transferred to the recording chamber, the preganglionic nerve trunk was drawn into a suction electrode for orthodromic stimulation. The ganglia were superfused continuously with a Krebs solution, saturated with 950 mL/L 02 and 5mL/L CO2, pH 7.4±0.05, (34±0.5) ℃.The fiber containing glass microelectrodes filled with 3 mol/L KC1 (30-60 MΩ tip resistance) were used to impaled cells and do intracellular recording. The fast excitatory postsynaptic potentials (FEPSPs) were evoked in SCG neurons by single pulse stimulations (0.2-0.5 Hz, 0.5-1.0 ms, 2-10 V)on preganglionic nerve trunk. The remarkable membrane depolarization would be recorded in SCG neurons by superfusing ganglia with exogenous Ach (0.1 mmol/L) or Carb(0.1 mmol/L) for 30-60 s. The effects of 1×(10-7-10-4) mol/L SmCl3 on FEPSPs, membrane potentials, membrane resistance, exogenous Ach and Carb-induced membrane depolarization of SCG neurons were investigated in this experiment.The effects of SmCl3 on the facilitation of high Ca2+ (10 mmol/L ) on FEPSPs were also be observed, namely, first superfusing the ganglia with high Ca2+ (10 mmol/L)to facilitate FEPSPs, then superfusing the ganglia with Ca2+(10 mmol/L)contained SmCl3. All the drugs were solved in Krebs solution or improved Krebs solution and applied to ganglia by superfusion in known concentration.The bioelectricity difference before and after the drug superfusion were analyzed by paired Student's t test.MAIN OUTCOME MESURES: ①Effects of SmCl3 on FEPSPs.②Effects of SmCl3 on membrane potentials and membrane resistances. ③Effects of SmCl3 on exogenous Ach and Carb-induced membrane depolarization. ④Effects of SmCl3 on the facilitation of high Ca2+ (10 mmol/L ) on FEPSPs.RESULTS: ① 1 ×(10-7-10-4)mol/L SmCl3 could reversibly depressed the FEPSPs of rats SCG neurons [the amplitude inhibitory percentage of FEPSPs of l×10-4, 1×10-5, 1×10-6, 1×107 mol/L SmCl3 was (49.78±13.85)%(n=20),(39.05±4.05)%(n=10),(29.83±9.73)%(n=10)and (16.30±2.16)%(n=10)respectively (P ＜ 0.05-0.01)].1×10-4 mol/L SmCl3 could chang Aps into FEPSPs (n=5).②The membrane depolarization induced by Ach (n=5) and Carb (n=7) were not significantly changed by 1×10-4 mol/L SmCl3(P ＞ 0.05).③The membrane potential and membrane resistance were not significantly altered by 1×(10-7-10-4)mol/L SmCl3(n=67), P ＞ 0.05. ④1×10-4 mol/L SmCl3 could antagonized the facilitation of high Ca2+ (10 mmol/L ) on FEPSPs (n=5), P ＜ 0.01.CONCLUSION: SmCl3 can depresses nicotinic transmission in rats sympathetic ganglia by presynaptic mechanisms, perhaps due to its inhibition on Ca2+ influx.

Objective To acquaint the condition of learning burnout of medical students and to explore the relationship of learning burnout with professional commitment and social support. Methods 610 medical students were evaluated with Learning Burnout Scale, professional commitment scale and social support scale. Results ①In general, learning burnout index of medical students was 2.84±0.49; in terms of gender difference, male students [(2.83±0.65) and (3.08±0.61)] were higher than females[(2.70±0.63) and (2.96±0.60)] at the level of emotional turndown and behavioral unsuitableness, the difference was statistically significant( P <0.05); in terms of grades, medical students'learning burnout of different grades was significant( F =4.244,P <0.01); there was no difference in profession. ②Learning burnout was significantly negative correlation with professional commitment and social support( P <0.01). ③Multiple regression analysis showed that affective commitment and family support had significant predications on learning burnout of medical students( P <0.01). Conclusion Medical students'learning burnout level is comparatively high, learning burnout closely relates to professional commitment and social support.

Food Contamination ; Humans ; Infant ; Triazines ; toxicity ; Urinary Calculi ; diagnosis ; etiology ; therapy

Histocytological Preparation Techniques ; methods ; Microtomy ; methods ; Tissue Embedding

Objectives:To detect the altered expression of SOCS-3 and GHR gene in intraabdominal infection and its relationship to growth hormone resistance.Methods:Liver expression of SOCS-3,GHR and IGF-I mRNA were detected by RT-PCR in control and intraabdominal infected rats,serum growth hormone levels were measured by RIA in two groups.Results:Serum concentrations of growth hormone were elevated more obviously in infected rats than controls,they were (0.843±0.17)ng/ml and (0.614±0.138)ng/ml respectively,the difference was significant (P<0.05).Liver GHR mRNA levels were decreased by 57.2% in infected rats compared with control rats.SOCS-3 mRNA was weakly expressed in control rats,however,it was strongly expressed in infected rats and had a 312.8 % increase.Liver IGF-I mRNA levels were reduced by 45.3% in infected rats compared with control rats.Conclusions:The elevated SOCS-3 and reduced GHR mRNA expression may contribute to the growth hormone resistance in intraabdominal infection.

Aim To study effects of morphine tolerance and dependence on the fast excitatory synaptic transmission in sympathetic ganglia of rats.Methods The isolated sympathetic ganglia,superior cervical ganglia(SCG), were made from control and morphine tolerant and dependent rats respectively.Effects of morphine tolerance and dependence on the fast excitatory synaptic transmission in rat sympathetic ganglia were studied by means of intracellular recording technique.Results ① Morphine(0.1～1.0 mmol?L~(-1))reversibly inhibited the amplitude of the fast excitatory postsynaptic potentials(f-EPSPs) in SCG neurons of control rats.② Compared with control group,inhibitory effects of morphine(0.5 mmol?L~(-1) and 1.0 mmol?L~(-1)) on f-EPSPs in SCG neurons of morphine tolerant and dependent rats were obviously decreased;③ Naloxone(0.1 mmol?L~(-1)),which had no significantly effect on f-EPSPs in SCG neurons of control rats,could reversibly facilitate the amplitude of f-EPSPs in SCG neurons of morphine tolerant and dependent rats;④ No significant difference of RMP and Rm was founded between SCG neurons of control and morphine tolerant and dependent rats.Conclusion The morphine tolerant and dependent of the fast excitatory synaptic transmission in rat sympathetic ganglia has been formed in morphine tolerant and dependent rats.

Objective:To investigate the effects of extracts of aqueous joint during CIA development on the HUVEC proliferation in vitro and expression of VEGF Methods: 3H TaR incorporation was used to estimate the HUVEC proliferation by extracts of aqueous joint and VEGF, and was used cultured in an absolutely serum free medium Results:Extracts of aqueqous joint during CIA development stimulated proliferation of HUVEC and this proliferation was inhibited by the anti VEGF neutralizing antibody Conclusion:The expression of VEGF in the extracts of the aqueous joint during an early stage of CIA development increased and expressed biologically active

Objective:To explore the influential factors of cognitive change among Chinese oldest-old.Method: Three waves of data from the Chinese Longitudinal Healthy Longevity Survey(CLHLS)were analyzed with a two-level repeated measures model.Results:In baseline,the male had a higher mean MMSE score than the female(27.0?3.7/24.4?5.6,P

The bilingual teaching must face some innovations and reformations in the contents and methods to acquire some satisfactory outcome.The article discusses some questions of bilingual teaching in paediatrics including the shortage of teachers,the interest deficiency of students,the lack of suitable teaching materials and inferior learning environment,and then provides some useful advice for the innovations of bilingual teaching.

Objectives:To investigate the role of endotoxin, TNF ? and IL 6 in inducing the growth hormone insensitivity at the receptor and post receptor levels. Methods:Spague Dawley rats were injected with endotoxin, TNF ?, and IL 6 respectively and were killed at different time points. The liver expressions of IGF 1, GHR and SOCS 3 mRNA were detected by RT PCR, the GH levels were measured by radioimmunoassay,and the levels of TNF ? and IL 6 were detected by ELISA. Results:Serum growth hormone levels at each time points after LPS iv injection did not have significant changes compared with control rats without iv injection of LPS, TNF ? and IL 6 levels were elevated rapidly after LPS injection, but TNF ? levels returned to normal quickly. The most remarkable down regulations for liver IGF 1 mRNA and GHR mRNA occurred at 12h and 8h respectively after LPS infusion. The liver SOCS 3 mRNA was weakly expressed in control rats. However, it was strongly up regulated after LPS injection and had a 7.84 times increase at 1h. The linear regression analysis had shown a positive correlation between IL 6 levels and liver SOCS 3 mRNA expressions. Liver GHR mRNA expression was obviously down regulated after TNF ? iv injection, but there was no effect on liver SOCS 3 mRNA expression. IL 6 up regulated the liver SOCS 3 mRNA expression, but it could not affect the liver GHR mRNA expression. Conclusions:The growth hormone insensitivity could be induced by LPS injection, which was associated with down regulated GHR mRNA expression at receptor level and up regulated SOCS 3 mRNA expression at post receptor level. The biological activities of LPS are mediated by TNF ? and IL 6 indirectly.And TNF ? and IL 6 exert their effects on the receptor and post receptor levels respectively, but the effect of TNF ? is of hysteresis.