Objective To evaluate the relationship between the level of AMP-activated protein kinase (AMPK) in hippocampus and cognitive dysfunction after splenectomy in aged rats.Methods Sixty-three male aged Sprague-Dawley rats,weighing 480-550 g,were randomly divided into 3 groups (n =21 each):control group (group C),anesthesia group (group A),and surgery group (group S).Morris water maze (MWM) test was performed to evaluate the spatial learning and memory ability before surgery and at 1,3 and 7 days after surgery.The escape latency and swimming distance were recorded.Seven rats were chosen after MWM test was performed at 1,3 and 7 days after surgery and sacrificed.Their hippocampi were removed for detection of the expression of AMPK and phosphorylated (p-AMPK) (by Western blot).Results Compared with the baseline,the escape latency and swimming distance were significantly prolonged at 1 and 3 days after surgery in group S (P ＜ 0.05).Compared with group C,the escape latency and swimming distance were significantly prolonged at 1 and 3 days after surgery,the expression of AMPK was up-regulated at 1,3 and 7 days after surgery,and the expression of p-AMPK was up-regulated at 1 and 3 days after surgery in group S (P ＜ 0.05),and no significant changes were found in the indices mentioned above in group A (P ＞ 0.05).Conclusion Increased AMPK level in hippocampus is the regulatory mechanism of the body adapting to the development of cognitive dysfunction after splenectomy in aged rats.

Objective To investigate the effect of mild hypothermia on glucose regulated protein 78 (GRP78) expression in hippocampus following transient cerebral ischemia-reperfusion (I/R) in aged rats.Methods One hundred and forty-four male aged Sprague-Dawley rats,weighing 450-550 g,were randomly divided into 3 groups (n=48 each): sham operation group (group S),I/R group and mild hypothermia group (group H).Global cerebral I/R was induced by 4-vessel occlusion method.Bilateral vertebral arteries were permanently occluded by cauterization,and bilateral carotid arteries were occluded for 5 min.The surface cooling was started immediately after reperfusion and maintained for 3 h.During surface cooling,the body temperature was maintained at 32-34 ℃(rectal).At 6,12,24 and 48 h of reperfusion,the expression of GRP78 was determined using immuno-histochemisty and Western blot,and the viable neurons in CA1 area were counted.Results The number of viable neurons was significantly smaller at each time point,and the expression of GRP78 was significantly higher at 6,12 and 24 h of reperfusion,while lower at 48 h of reperfusion in I/R group,and the number of viable neurons was significantly smaller,and the expression of GRP78 was significantly higher at each time point in group H than in group S (P＜ 0.05).The number of viable neurons was significantly larger at 12,24 and 48 h of reperfusion,and the expression of GRP78 was significantly higher at each time point in group H than in group I/R (P ＜ 0.05).Conclusion Mild hypothermia can further up-regulate GRP78 expression in hippocampus following transient cerebral I/R in aged rats,thus reducing endoplasmic reticulum stress and cerebral I/R injury.

Objective To evaluate the usefulness of mycolic acid for identification of Mycobacterium species using SMIS. Methods One hundred and eighteen clinical Mycobacterium isolates collected from Beijing Tuberculosis and Thoracic Tumor Research Institute through whole year of 2007 were analyzed. The 118 isolates contain 25 isolates of Mycobacterium tuberculosis and 93 non tuberculosis Mycobacterium identified by PNB method. Mycolic acid analysis using SMIS is evaluated for identification of a broad range of Mycobacteria in comparison with 16S rDNA , 16-23S rDNA ITS sequencing to measure the concordance rate and agreement, and verify the concordance rate and agreement among results of mycolic acid, sequencing and PNB in identifying Mycobacterium tuberculosis and non tuberculosis Mycobacterium. Results The concordance rate between mycolic acid method analysis and DNA sequencing is 92% ( 108/118), of which concordance rate in Mycobacterium tuberculosis complex and non tuberculosis Mycobacterium are 95% (35/37) and 90% (73/81) respectively, agreement of both is great( agreement Kappa value is 0. 96). Through retrospective analysis, the concordance of results between SMIS and PNB method analysis is 90% (106/118)and agreement is well( agreement Kappa value is 0. 73 ), the concordance of results between sequencing and PNB method analysis is also 90% ( 106/118 ) and agreement is well (agreement Kappa value is 0. 74 ),despite the identification results of 11 isolates by PNB method are discordant. Conclusion Mycolic acid analysis by SMIS enables rapid identification of a broad range of clinical Mycobacterium species, which could play an important role in polyphasic identification of Mycobacterium species.

Objective To evaluate the effect of PUN282987 on global cerebral ischemia-reperfusion (I/R) injury in aged rats.Methods One hundred and twenty pathogen-free healthy male SpragueDawley rats,aged 18-22 months,weighing 450-600 g,were divided into 3 groups (n=40 each) using a random number table:sham operation group (group S),global cerebral I/R group (group I/R) and α7 nicotinic acetylcholine receptor (α7nAChR) agonist PNU282987 group (group PUN).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 0.4 ml/100g,and global cerebral I/R was produced by 4-vessel occlusion technique in I/R and PUN groups.PUN282987 2.4 mg/kg was injected intraperitoneally before ischemia in group PUN.At 1,5,12 and 24 h of reperfusion,10 rats were randomly selected in each group and then sacrificed,and the brains were removed for detection of the neuronal apoptosis and for determination of the expression of α7nAChR,choline acetyltransferase (ChAT),tumor necrosis factor-α (TNF-α) and intedeukin-1β (IL-1β) in the hippocampal CA1 region.Apoptosis rate was calculated.Results Compared with group S,the apoptosis rate was significantly increased,and the expression of α7nAChR,ChAT,TNF-α and IL-1β was up-regulated at each time point in I/R and PUN groups (P＜0.05).Compared with group I/R,the apoptosis rate was significantly decreased,the expression of α7nAChR and ChAT was up-regulated,and the expression of TNF-α and IL-1β was down-regulated at each time point in group PUN (P＜0.05).Conclusion PUN282987 can reduce global cerebral I/R injury in aged rats.

Objective To investigate the impact of ethyl pyruvate (EP) on cognitive function and the expression of high mobility group box 1 (HMGB1) and receptor for advanced glycation end products (RAGE) after splenectomy in aged rats.Methods Eighty-four male aged Sprague-Dawley rats, 18 months old, weighing 500-600 g, were randomly divided into 4 groups (n=21 each) by random number table method: control group (group C), surgery group (group S) ethyl pyruvate group (group E) and solution without EP group (group R).Morris water maze test was performed to evaluate cognitive function 5 days before surgery and 1, 3, 7 days after surgery.Group E was injected with EP 40 mg/kg intrapertoneally after splenectomy, group S and group C were injected with equivalent normal saline after splenectomy, group R was injected with equivalent solution without EP.Rats were killed after Morris water maze test, and the expression of HMGB1 and RAGE protein and mRNA in hippocampus were measured by Western blot and RT-PCR methods.Results Compared with group C, the escape latency and swimming distance were significantly prolonged in groups S, E and R 1 and 3 days after surgery, as well as the expression of HMGB1 and RAGE in hippocampus were significantly up-regulated (P＜0.05).Compared with group S, the escape latency and swimming distance were significantly decreased and the expression of HMGB1 and RAGE were down-regulated in group E 1 and 3 days after surgery (P＜0.05).Compared with the preoperative group, the escape latency and swimming distance were significantly prolonged in groups S, E and R 1 and 3 days after surgery (P＜0.05).Conclusion EP may improve cognitive function in aged rats by down regulating the expression of HMGB1 and RAGE in the hippocampus.

Objective To evaluate the effect of dexmedetomidine on the mammalian target of rapamycin(mTOR)/tau protein signaling pathway in the hippocampus of aged rats after splenectomy.Methods One hundred and fifty pathogen-free healthy male Sprague-Dawley rats,aged 18 months,weighing 400-540 g,were divided into 5 groups(n=30 each)using a random number table:control group(group C),sham operation group(group S),operation group(group O),normal saline group(group NS)and dexmedetomidine group(group D).Group C received no treatment.Ten percent chloral hydrate 0.3 ml/100 g was injected intraperitoneally in group S.Group O underwent splenectomy.Dexmedetomidine 50 μg/kg was injected intraperitoneally at 5 min before splenectomy in group D.The equal volume of normal saline was injected intraperitoneally at 5 min before splenectomy in group NS.Morris water maze test was performed at day 7 after surgery.At days 1,3 and 7 after surgery,the rats were sacrificed,and the hippocampi were removed for examination of the pathological changes in the hippocampal CA3 region and for determination of the expression of mTOR protein and mRNA,tau protein mRNA and phosphor-tau protein(pS396 tau protein)(by real-time polymerase chain reaction or Western blot).Results Compared with group C,the escape latency and swimming distance were significantly prolonged,and the expression of mTOR protein and mRNA,tau protein mRNA and pS396 tau protein was up-regulated in O,D and NS groups(P<0.05),and no significant change was found in the parameters mentioned above in group S(P>0.05).Compared with group O,the escape latency and swimming distance were significantly shortened,and the expression of mTOR protein and mRNA,tau protein mRNA and pS396 tau protein was down-regulated in group D(P<0.05),and no significant change was found in the parameters mentioned above in group NS(P>0.05).The pathological changes in the hippocampal CA3 region were significantly attenuated in group D as compared with group O.Conclusion The mechanism by which dexmedetomidine improves postoperative cognitive function may be associated with inhibited activation of mTOR/tau protein signaling pathway in the hippocampus of aged rats.

Objective To evaluate the accuracy of cerebrospinal fluid (CSF) amyloid beta 42 (Aβ-42) to tau level ratio (Aβ-42/tau) in predicting postoperative cognitive dysfunction (POCD) in elderly patients.Methods Eighty ASA physical status Ⅱ or Ⅲ patients of both sexes,aged 65-85 yr,undergoing elective total hip or knee replacement under combined spinal-epidural anesthesia,were enrolled in the study.Epidural catheter was placed at T3,4 interspace,and after a catheter was successfully placed into the subarachnoid space,CSF 2 ml was obtained to measure Aβ-42 and tau levels (units:pg/ml),and the ratio between them was calculated.Neuropsychological tests were performed at 1 day before surgery and 1 week after surgery.The Z score was used to identity POCD.The cut-off value for POCD and nonPOCD patients was determined by using ROC curve.Results Thirty-two patients were diagnosed with POCD,and the incidence was 40％.The Aβ-42/tau was 2.6±0.3 and 1.7±0.4 in non-POCD and POCD groups,respectively,and the ratio was significantly lower in POCD group than in non-POCD group.The sensitivity of CSF Aβ-42/tau in predicting POCD was 91.7％,the specificity was 81.2％,and Youden index was 0.7.ROC curves revealed that the cut-off value for POCD and non-POCD patients was 2.0.Conclusion CSF Aβ-42/tau can accurately predict the occurrence of POCD in elderly patients.

Objective To evaluate the role of hippocampal mammalian target of rapamycin (mTOR) signaling pathways in the cognitive dysfunction after splenectomy in aged rats.Methods Sixtythree male Sprague-Dawley rats,aged 18 months,weighing 400-540 g,were randomly divided into 3 groups (n=21 each) using a random number table:control group (group C),operation group (group O) and mTOR inhibitor rapamycin group (group M).Morris water maze test was performed to evaluate cognitive function before operation and at 1,3 and 7 days after operation.After the end of Morris water maze test carried out at 1,3 and 7 days after operation,7 rats selected randomly in each group were sacrificed,and the brains were removed for detection of the expression of mTOR and phosphorylated tau protein at Ser-396 site (pS396 tau) in hippocampal tissues by using Western blot.Results Compared with group C,the escape latency was significantly prolonged,the ratio of time spending in the target quadrant was decreased,and the expression of pS396 tau was up-regulated at 1 and 3 days after operation,and the expression of mTOR was up-regulated at each time points after operation in group O,and the escape latency was significantly prolonged,the ratio of time spending in the target quadrant was decreased,and the expression of mTOR and pS396 tau was up-regulated at 1 and 3 days after operation in group M.Compared with group O,the escape latency was significantly shorten,the ratio of time spending in the target quadrant was increased,and the expression of pS96 tau was down-regulated at 1 and 3 days after operation,and the expression of mTOR was down-regulated at each time point after operation in group M.Conclusion The hippocampal mTOR signaling pathways are involved in the development of cognitive dysfunction after splenectomy in aged rats.

Objective To investigate the effects of hydrogen-rich saline on hippocampal mammalian target of rapamycin (mTOR)/tau pathway after operation in aged rats.Methods One hundred fifty healthy male Sprague Dawley rats, aged 18 months, weighing 400-540 g, were randomly divided into 5 groups (n=30 each) using a random number table: control group (group C);sham operation group (group S);operation group (group O);hydrogen-rich saline treatment group (group HS);normal saline group (group NS).Splenectomy was performed in group O.Hydrogen-rich saline 1 ml/100 g was injected intraperitoneally at 5 min before splenectomy in group HS.Normal saline 1 ml/100g was injected intraperitoneally at 5 min before splenectomy in group NS.Morris water maze test was performed at 1, 3 and 7 days after surgery, and the escape latency and swimming distance were recorded.After the end of the test, the rats were sacrificed, and the brains were removed for examination of the pathological changes in the hippocampal CA3 region (under light microscope), and for determination of the expression of mTOR mRNA and tau mRNA (using reverse transcriptase polymerase chain reaction) and mTOR and pS396 tau (by Western blot).Results Compared with C and S groups, the escape latency and swimming distance were significantly prolonged, and the expression of mTOR protein and mRNA, tau mRNA and pS396 tau was up-regulated in O, HS and NS groups (P＜0.05).Compared with O and NS groups, the escape latency and swimming distance were significantly shortened, and the expression of mTOR protein and mRNA, tau mRNA and pS396 tau was down-regulated in group HS (P＜0.05).The pathological changes of the hippocampal tissues were mitigated in group HS when compared with group O.Conclusion The mechanism by which hydrogen-rich saline mitigates postoperative cognitive dysfunction may be associated with inhibited activation of hippocampal mTOR/tau pathway in aged rats.

Objective To investigate the changes in the expression of hippocampal occludin and claudin-5 after operation in aged rats.Methods Eighty-one healthy male Wistar rats, aged 16-18 months, weighing 400-500 g, were randomly assigned into 3 groups (n =27 each) using a random number table: normal control group (group C), skin incision group (group I) and splenectomy group (group S).Splenectomy was performed in group S.Only skin incision and closing were performed in group I.Morris water maze test was performed before operation and on 1, 3 and 7 days after operation.The escape latency and the percentage of time spent at the target platform quadrant were recorded.Nine rats randomly selected from each group were sacrificed after the end of the test, and the hippocampi were isolated to detect the expression of occludin and claudin-5 by Western blot.Results Compared with group C, the escape latency was significantly prolonged, the percentage of time spent at the target platform quadrant was decreased, the expression of hyperphosphorylated occludin and claudin-5 was down-regulated, and the expression of hypophosphorylated occludin was up-regulated on 1 and 3 days after operation in group S (P＜0.05).Conclusion The mechanism of postoperative cognitive dysfunction is related to the downregulated expression of hippocampal hyperphosphorylated occludin and claudin-5 in aged rats.