Objective To evaluate the effect of dexmedetomidine on noise-induced hearing loss in guinea pigs.Methods Twenty-four adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 3 groups (n =8 each) using a random number table:dexmedetomdine group (group D),noise-induced hearing loss group (group N) and dexmedetomidine + noise-induced hearing loss group (group DN).A loading dose of dexmedetomidine 5 μg/kg was infused over 5 min,followed by 135 min of infusion at a rate of 10 μg· kg-1 · h-1.The equal volume of normal saline was infused in group N.Groups N and DN were exposed to noise of 4 kHz center frequency and 118-122 dB SPL for 120 min starting from 20 min of administration.Mean arterial pressure (MAP) and cochlear blood flow (COBF) were recorded before administration and every 5 min during drug administration.The changing rate of COBF was calculated.Arterial blood samples were collected for determination of plasma concentration of noradrenaline (NE) by high performance liquid chromatography at 20 and 140 min of administration.Auditory brainstem response (ABR) threshold was recorded before administration and at 1 and 72 h and 10 days after the end of administration.Results Compared with group N,MAP was significantly decreased,the changing rate of COBF was increased at 5-10 min and 30-140 min of administration,ABR threshold was decreased at 1 and 72 h and 10 days after the end of administration,and the plasma concentration of NE was decreased at 140 min of administration in D + N group (P ＜ 0.05).Conclusion Dexmedetomidine can attenuate noise-induced hearing loss in guinea pigs possibly through inhibiting activation of sympathetic nerves and increasing COBF.

Objective To evaluate the in vitro antimicrobial activity of piperacillin-sulbactam against clinical isolates of non-fermentative bacilli isolated from common infections. Methods Microdilution was employed to study the antimicrobial resistance. Results A total of 770 strains were collected from 6 hospitals in Guangzhou, including Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia , Burkholderia cepacia , Flavobacterium , and Alcaligenes. Compared with other β-lactams,piperacillin-sulbactam displayed the highest activity against all the isolates of P. aeruginosa, especially for imipenem non-sensitive isolates, with the susceptibility of 71.9% and 55.8%, respectively. Piperacillinsulbactam and cefoperazone-sulbactam kept good activity against imipenem sensitive isolates of A. baumannii,with the susceptibility of 71.0% and 73. 0%, respectively. For the strains of Burkholderia cepacia, 69% strains exhibited minimal inhibitory concentration (MIC) of ≤ 16 mg/L for piperacillin-sulbactam. For the strains of Flavobacterium, and Alcaligenes, piperacillin-sulbactam also had excellent activity, with the susceptibility of 70. 2% and 94. 4%, respectively. Conclusion Piperacillin-sulbactam exhibits good activity again non-fermentative bacilli, especial for imipenem non-sensitive isolates of P. aeruginosa.

Objective To evaluate the effect of isoflurane anesthesia on noise-induced hearing loss in guinea pigs.Methods Forty-eight healthy adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 4 groups (n =12 each) using a random number table:control group (C group),isoflurane group (I group),noise-induced hearing loss group (N group),and isoflurane + noise-induced hearing loss group (I + N group).Isoflurane was inhaled for 140 min at a concentration of 1％ in I and I + N groups.N and I + N groups were exposed to the noise of 4 kHz center frequency and 118-122 dB sound pressure level for 120 min starting from 20 min after administration.Mean arterial pressure (MAP) was recorded at 10,40,70,100 and 120 min of exposure to noise and cochlear blood flow (CoBF) was recorded before administration and at 10,40,70,100 and 120 min of exposure to noise.Auditory brainstem response (ABR) threshold was recorded before administration and at 1 h,72 h,and 10 days after the end of exposure to noise.Arterial blood samples were obtained and the plasma noradrenaline (NE) concentration was detected by HPLC before exposure to noise and immediately after the end of exposure to noise.Results Compared with group C,MAP and the change rate of CoBF were significantly decreased,and the plasma NE concentration was increased immediately after the end of exposure to noise in I group,and MAP was increased,the change rate of CoBF was decreased,and the plasma NE concentration immediately after the end of exposure,and ABR threshold after the end of exposure were increased in N and I + N groups.Compared with N group,MAP was significantly decreased,the change rate of CoBF was increased,the plasma NE concentration immediately after the end of exposure,and ABR threshold at 1 and 72 h after the end of exposure were increased,and no significant was found in ABR threshold at 10 days after the end of exposure in I + N group.Conclusion Isoflurane anesthesia exerts temporary but not permanent protective effects against noise-induced hearing loss in guinea pigs and partial inhibition of activation of sympathetic nerve and increased CoBF may be involved in the mechanism.

Objective To evaluate the effect of propofol on noise-induced hearing loss in guinea pigs.Methods Forty-eight healthy adult male guinea pigs,aged 3 months,weighing 400-500 g,were randomly divided into 4 groups (n =12 each) using a random number table:control grotup (C group),propofol group (P group),noise-induced hearing loss group (N group),and propofol + noise-induced hearing loss group (P + N group).A loading dose of propofol 5 mg/kg was infused intravenously over 5 min,followed by infusion at 20 mg· kg-1 · h-1 for 115 min in P and P + N groups,while the equal volume of normal saline was given in N group.N and P+ N groups were exposed to the noise of 4 kHz center frequency and 118-122 dB sound pressure level for 120 min.Distortion product otoacoustic emission (DPOAE) was measured before noise exposure (T1) and at 1 h after the end of noise exposure (T2) and the amplitudes were recorded at the frequencies of 2,4,6 and 8 kHz.After the second measurement of DPOAE,all the animals were sacrificed and organs of Corti were harvested for determination of cochlear 8-isoprostaglandin F(2alpha) (8-iso-PGF2α) content (by ELISA assay) and out hair cell (OHC) count.The rate of OHC lesions was calculated.Results The DPOAE amplitude was significantly lower at frequencies of 4,6 and 8 kHz at T2 than at T1 in N and P + N groups (P ＜ 0.05).Compared with C group,the DPOAE amplitude was significantly decreased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-isoPGF2α content and rate of OHC lesions were increased in N and P + N groups (P ＜ 0.05).Compared with N group,the DPOAE amplitude was significantly increased at frequencies of 4,6 and 8 kHz at T2,while the cochlear 8-iso-PGF2α content and rate of OHC lesion were decreased in P + N group (P ＜ 0.05).Conclusion Propofol can reduce noise-induced hearing loss in guinea pigs possibility through decreasing oxidative stress response-induced damage to cochlear OHCs.

Objective To investigate serum galectin-3 levels in patients with chronic heart failure and evaluate its clinical significance for heart failure.Methods A total of 108 chronic heart failure patients were selected.The selected patients were divided into three groups according to the classification of New York Heart Association (NYHA,from degree Ⅱ to Ⅳ).In addition,30 healthy persons were chosen as control group.All the patients received cardiac ultrasound examination.Plasma levels of N-terminal probrain natriuretic peptide (NT-proBNP),serum levels of galectin-3 and interleukin-6 (IL-6) were measured and analyzed.Results Galectin-3 levels were significantly higher in chronic heart failure patients compared with control group(P ＜ 0.05).In chronic heart failure group,the increase of serum concentration of galectin-3 was correlated with the degree of NYHA function classification.Correlation analysis showed that blood level of galectin 3 was strongly positive correlation with concentration of NT-proBNP and IL-6.There was no correlation between galectin-3 with the cause of heart failure,left ventricular diameter(LVD),and left ventricular ejection fraction (LVEF).Conclusions The levels of galectin-3 was significantly increased in chronic heart failure,and was correlated with degree of heart failure.Galectin-3 might be a new biomarker of heart failure and could provide additive value to NT-proBNP levels in the diagnosis of heart failure.

The changes of intracranial components and corr esponding brain impedan ce were analyzed while intracranial pressure was increasing, and the relation of intr acranial pressure pulse wave and brain impedance pulse wave were discussed. A theory of noninvasive intracranial pressure monitoring by bioelectric impedance was put forward. The result of primary experiment suggested that the theory be feasible.