Protective effect and mechanism of nanoantimicrobial peptide ND-C14 against Streptococcus pneumoniae infection / 世界急诊医学杂志（英文）

@#BACKGROUND: Streptococcus pneumoniae (S. pneumoniae) is a common pathogen that causes bacterial pneumonia. However, with increasing bacterial resistance, there is an urgent need to develop new drugs to treat S. pneumoniae infections. Nanodefensin with a 14-carbon saturated fatty acid (ND-C14) is a novel nanoantimicrobial peptide designed by modifying myristic acid at the C-terminus of human α-defensin 5 (HD5) via an amide bond. However, it is unclear whether ND-C14 is effective against lung infections caused by S. pneumoniae. METHODS: In vitro, three groups were established, including the control group, and the HD5 and ND-C14 treatment groups. A virtual colony-count assay was used to evaluate the antibacterial activity of HD5 and ND-C14 against S. pneumoniae. The morphological changes of S. pneumoniae treated with HD5 or ND-C14 were observed by scanning electron microscopy. In vivo, mice were divided into sham, vehicle, and ND-C14 treatment groups. Mice in the sham group were treated with 25 µL of phosphate-buffered saline (PBS). Mice in the vehicle and ND-C14 treatment groups were treated with intratracheal instillation of 25 µL of bacterial suspension with 2×108 CFU/mL (total bacterial count: 5×106 CFU), and then the mice were given 25 μL PBS or intratracheally injected with 25 μL of ND-C14 (including 20 µg or 50 µg), respectively. Survival rates were evaluated in the vehicle and ND-C14 treatment groups. Bacterial burden in the blood and bronchoalveolar lavage fluid were counted. The lung histology of the mice was assessed. A propidium iodide uptake assay was used to clarify the destructive effect of ND-C14 against S. pneumoniae. RESULTS: Compared with HD5, ND-C14 had a better bactericidal effect against S. pneumoniae because of its stronger ability to destroy the membrane structure of S. pneumoniae in vitro. In vivo, ND-C14 significantly delayed the death time and improved the survival rate of mice infected with S. pneumoniae. ND-C14 reduced bacterial burden and lung tissue injury. Moreover, ND-C14 had a membrane permeation effect on S. pneumoniae, and its destructive ability increased with increasing ND-C14 concentration.

Effect of nimodipine pretreatment on postoperative cognitive function in diabetic rats / 中华麻醉学杂志

Objective To evaluate the effect of nimodipine pretreatment on postoperative cognitive function in diabetic rats. Methods One hundred and eighty healthy male Wistar rats, aged 3-4 months, weighing 260-310 g, were divided into 6 groups ( n=30 each) using a random number table method: op-eration group ( O group) , diabetes mellitus group ( DM group) , diabetic cognitive impairment group ( DCI group) , nimodipine plus operation group ( N+O group) , nimodipine plus diabetes mellitus group ( N+DM group) and nimodipine plus diabetic cognitive impairment group ( N+DCI group) . Diabetes mellitus model was established by intraperitoneal injection of streptozotocin 55 mg∕kg. Nimodipine 1 mg∕kg was intraperito-neally injected at 6 weeks after establishing the model in DCI and N+DCI groups and at 2 weeks after estab-lishing the model in DM and N+DM groups, and laparotomy was performed under sevoflurane anesthesia at 30 min after the end of administration. Morris water maze test was performed at 1 day before operation and 3 and 7 days after operation. Then rats were sacrificed, and hippocampal tissues were taken for determination of the apoptotic rate of neurons, cytoplasmic calcium concentrations ( by flow cytometry) and expression of caspase-3 in hippocampus ( by Western blot) . Results Compared with the baseline at 1 day before opera-tion, the escape latency was significantly prolonged, the number of crossing the original platform was re-duced, the apoptotic rate of hippocampal neurons and cytosolic calcium concentrations were increased, and the expression of caspase-3 was up-regulated at each time point after operation in six groups ( P<0. 05 ) . Compared with group O, the escape latency was significantly prolonged, the number of crossing the original platform was reduced, the apoptotic rate of hippocampal neurons and cytosolic calcium concentrations were increased, and the expression of caspase-3 was up-regulated at each time point after operation in DM and DCI groups ( P<0. 05) . The escape latency was significantly shortened, the number of crossing the original platform was increased, the apoptotic rate of hippocampal neurons and cytosolic calcium concentrations were decreased, and the expression of caspase-3 was down-regulated at each time point after operation in group N+DM as compared with group DM and in group N+DCI as compared with group DCI ( P<0. 05) . Conclu-sion Nimodipine pretreatment can improve postoperative cognitive function in diabetic rats, and the mech-anism may be related to inhibiting calcium overload-induced apoptosis in neurons.

Effect of nimodipine pretreatment on postoperative cognitive function in rats with chronic cerebral ischemia / 中华麻醉学杂志

Objective To evaluate the effect of nimodipine pretreatment on postoperative cognitive function in rats with chronic cerebral ischemia.Methods Sixty healthy male Sprague-Dawley rats,aged 3 months,weighing 250-350 g,were divided into 2 groups (n =30 each) using a random number table method:chronic cerebral ischemia operation group (group H) and nimodipine plus chronic cerebral ischemia operation group (group N+H).The chronic cerebral ischemia model was established by permanently ligating bilateral common carotid arteries of chloral hydrate-anesthetized rats.Rats underwent Morris water maze adaptive training for 5 days 2 weeks later.Nimodipine 1 mg/kg was intraperitoneally injected on 1st day after the end of adaptive training in group N+H,while the equal volume of normal saline was given instead in group H,and 30 min later splenectomy was performed under sevoflurane anesthesia in two groups.Ten rats in each group were selected on 1 day before operation and 3 and 7 days after operation and underwent Morris water maze test to assess cognitive function.The rats were then sacrificed,brains were removed,and hippocampal tissues were isolated for determination of apoptosis in hippocampal neurons and intracellular Ca2+concentrations([Ca2+]i) in cytoplasm and expression of Bcl-2 and Bax mRNA (by realtime polymerase chain reaction).The ratio of Bax mRNA to Bcl-2 mRNA was calculated.Results Compared with the baseline at 1 day before operation,the escape latency was significantly prolonged,the frequency of crossing the original platform was decreased,the apoptotic rate and [Ca2+] i were increased,Bcl2 mRNA expression was down-regulated,and Bax mRNA expression was up-regulated,and Bax mRNA/Bcl-2 mRNA ratio was increased at each time point after operation in two groups (P＜0.05).Compared with group H,the escape latency was significantly shortened,the frequency of crossing the original platform was increased,the apoptotic rate and [Ca2+]iwere decreased,Bcl-2 mRNA expression was up-regulated,and Bax mRNA expression was down-regulated,and Bax mRNA/Bcl-2 mRNA ratio was decreased at each time point after operation in group N+ H (P＜ 0.05).Conclusion Nimodipine pretreatment can improve the postoperative cognitive function of rats with chronic cerebral ischemia,and the mechanism may be related to inhibiting calcium overload-induced apoptosis in hippocampal neurons.

Effects of laparotomy on cognitive function in rats with traumatic brain injury and the realationship with calcium overload / 中华行为医学与脑科学杂志

Objective To evaluate the effect of laparotomy on cognitive function in rats with trau-matic brain injury and the relationship with calcium overload. Methods One hundred and fifty healthy male Wistar rats,aged 2~3 months,weighing 190~220 g,were assigned into 5 group ( n=30 each) using a ran-dom number table:blank group(group B),surgery group of blank rats(group BS),surgery group of sham rats (group SS),traumatic brain injury rats group( group T),surgery group of traumatic brain injury rats(group TS). TBI model was made in rats of group T and TS by Feeney method. Rats in group SS were only treated with cranial bone window without crainocerebral impact. Both group B and BS were normal rats. Then the rats in group BS,SS and TS group underwent laparotomy under sevoflurane anesthesia (the operation time was a-bout 3 hours) and the rats in group B and T inhaled pure oxygen for 3 hours after 20 days. One day before surgery,3 and 7 d after surgery,10 rats in each group were randomly selected for Morris water maze test. The hippocampus tissue of 10 rats were taken after the water maze test. The apoptosis rate and calcium concen-tration of hippocampal neurons were measured by flow cytometry,and the expression level of cleaved caspase-3 in hippocampal tissues was determined by Western blot. Results One day before surgery,compared with group B(the escape latency(9. 8±0. 8)s,the number of crossing platform (5. 8±0. 8),the apoptosis rate of hippocampal neurons ( 2. 5 ± 0. 9)%, calcium ion concentration ( 2. 3 ± 0. 2),the expression of cleaved caspase-3 (0. 22±0. 07) ),the escape latency of group T and group TS were prolonged (group T:(25. 5± 0. 7)s,P<0. 05;group TS:(25. 1±1. 1) s,P<0. 05),the number of crossing platform decreased (group T:(2. 7±0. 8),P<0. 05;group TS:(2. 8±0. 6),P<0. 05),the apoptosis rate of hippocampal neurons increased (group T:(5. 3±0. 6)%,P<0. 05;group TS:(5. 2±1. 0)%,P<0. 05),calcium ion concentration increased (group T:(3. 7±0. 4),P<0. 05;group TS:(3. 6±0. 5),P<0. 05) and the expression of cleaved caspase-3 increased (group T:(0. 45±0. 07),P<0. 05;group TS:(0. 44±0. 05),P<0. 05),the differences were statis-tically significant. Compared with the group SS,the escape latency ( 3 d after surgery:group SS:( 23. 8 ± 1. 3)s,group TS:(56. 4±2. 5)s,P<0. 05;7 d after surgery:group SS:(16. 6±1. 8)s,group TS:(38. 1±2. 1) s,P<0. 05)of the rats in group TS were prolonged,the number of crossing platform decreased (3 d after sur-gery:group SS:(2. 9±0. 6) ,group TS:(1. 1±1. 1) ,P<0. 05;7 d after surgery:group SS:( 4. 2± 1. 2) , group TS:(1. 7±1. 3),P<0. 05),the apoptosis rate of hippocampal neurons ( 3 d after surgery:group SS:(4. 8±0. 6)%,group TS:(14. 4± 0. 6)%,P<0. 05;7 d after surgery:group SS:(3. 8± 1. 1)%,group TS:(9. 6±1. 3)%,P<0. 05),calcium ion concentration ( 3 d after surgery:group SS:(3. 1± 0. 3),group TS:(6. 4±0. 5),P<0. 05;7 d after surgery:group SS:( 2. 6± 0. 3),group TS:( 4. 8± 0. 4),P<0. 05) ,the ex-pression of cleaved caspase-3 (3 d after surgery:group SS:( 0. 42± 0. 03),group TS:( 0. 88 ± 0. 08),P<0. 05;7 d after surgery:group SS:(0. 33±0. 05),group TS:(0. 63±0. 06),P<0. 05) in the hippocampus in-creased after surgery (P<0. 05). Compared with the T group,the escape latency (3 d after surgery:group T:( 18. 6±2. 0)s,group TS:(56. 4±2. 5)s,P<0. 05;7 d after surgery:group T:(13. 8±2. 6)s,group TS:(38. 1 ±2. 1)s,P<0. 05) of the rats in group TS were prolonged,the number of crossing platform (3 d after surger-y:group T:(3. 4±0. 5),group TS:(1. 1±1. 1),P<0. 05;7 d after surgery:group T:(4. 3±1. 2),group TS:(1. 7±1. 3),P<0. 05) decreased,the apoptosis rate of hippocampal neurons (3 d after surgery:group T:(4. 4±0. 7)%,group TS:( 14. 4 ± 0. 6)%,P<0. 05;7 d after surgery:( 3. 3 ± 1. 3)%,group TS:( 9. 6 ± 1. 3)%,P<0. 05),calcium ion concentration (3 d after surgery:group T:( 3. 4 ± 0. 4),group TS:( 6. 4 ± 0. 5),P<0. 05;7 d after surgery:group T:(3. 0±0. 3),group TS:(4. 8±0. 4),P<0. 05),the expression of cleaved caspase-3 (3 d after surgery:group T:(0. 40±0. 04),group TS:( 0. 88±0. 08),P<0. 05;7 d after surgery:(0. 35±0. 02),group TS:(0. 63±0. 06),P<0. 05) in the hippocampus increased after surgery(P<0. 05). Conclusion Laparotomy can aggravate the cognitive impairment of rats with traumatic brain injury and cause postoperative cognitive impairment,which may be related to the increased degree of calcium over-load and the increased rate of hippocampal neuron apoptosis.

Effect of nimodipine pretreatment on postoperative cognitive function in rats with cerebral ischemic stroke / 中华麻醉学杂志

Objective To evaluate the effect of nimodipine pretreatment on postoperative cognitive function in rats with cerebral ischemic stroke.Methods Sixty healthy male Sprague-Dawley rats,aged 3 months,weighing 250-350 g,were divided into 2 groups (n =30 each) using a random number table method:normal saline plus cerebral ischemic stroke group (group Ⅰ) and nimodipine plus cerebral ischemic stroke group (group N+Ⅰ).The cerebral ischemic stroke model was established by thread occlusion in two groups.Three weeks later,nimodipine 1 mg/kg was intraperitoneally injected in group N+Ⅰ,while the equal volume of normal saline was given instead in group Ⅰ,and 30 min later two groups underwent exploratory laparotomy under 1.7％ sevoflurane anesthesia.Eight rats in each group were randomly selected on 1 day before operation and 3 and 7 days after operation,and Morris water maze test was performed to assess cognitive function.The rats were then sacrificed,brains were removed,and hippocampal tissues were isolated for detection of apoptosis in hippocampal neurons,intracellular Ca2+concentration ([Ca2+]i) in cytoplasm and the expression of Bcl-2 and Bax mRNA (by real-time polymerase chain reaction).The ratio of Bax mRNA to Bcl-2 mRNA was calculated.Results Compared with the value at 1 day before operation,the escape latency was significantly prolonged,the frequency of crossing the original platform was decreased,apoptotic rate and [Ca2+] i were increased,Bcl-2 mRNA expression was down-regulated,Bax mRNA expression was up-regulated,and Bax mRNA/Bcl-2 mRNA ratio was increased at each time point after operation in two groups (P＜0.05).Compared with group Ⅰ,the escape latency was significantly shortened,the frequency of crossing the original platform was increased,the apoptotic rate and [Ca2 +]i were decreased,Bcl-2 mRNA expression was up-regulated,Bax mRNA expression was down-regulated,and Bax mRNA/Bcl-2 mRNA ratio was decreased at each time point after operation in group N+Ⅰ (P＜0.05).Conclusion Nimodipine pretreatment can improve the postoperative cognitive function of rats with cerebral ischemic stroke,and the mechanism may be related to inhibiting calcium overload-induced apoptosis in hippocampal neurons.

Establishment of a new depression rat model based on antagonistic relationship of brain neurotransmitter pairs / 中国病理生理杂志

AIM:To establish a new rat model of depression by the antagonistic relationship of antagonizing pairs of neurotransmitters in the brain.METHODS:Dopamine D1 receptor antagonist SCH23390 was injected into the hippocampus of the rats by microinjection at low, medium and high doses (1, 2 and 4 g/L) to establish a depression model.After modeling, the sucrose consumption, open-field and novelty suppressed feeding tests were used to evaluate the behaviors of the rats, and screen out the best modeling drug dose.The model of depressive rats was induced using the best modeling drug dose and the model rats were observed for 2 weeks.The stability of the model was evaluated by behavioral tests, and the contents of IL-1β and TNF-α in cerebrospinal fluid (CSF) were measured by ELISA to evaluate the safety of the model.The levels of the antagonizing pairs of neurotransmitters in the cerebral cortex and hippocampus were analyzed by the method of high-performance liquid chromatography-mass spectrometry (HPLC-MS), so as to evaluate the pathological characteristics of neurotransmitter imbalance in the brain of the model rats.RESULTS:After modeling, the rat weight, sucrose preference rate, and horizontal motion and vertical motion scores of open-field test were significantly decreased in eACh dose model group, and feeding latent periods of novelty suppressed feeding test were significantly increased, indicating a typical depressive behavior.The rats with the medium dose (2 g/L) of SCH23390 had the most significant depressive behavior.At 2 weeks after modeling, compared with the normal control group, the weight, sucrose preference rate, and horizontal motion and vertical motion scores in medium dose group were significantly decreased (P<0.01), while the feeding inhibition time was significantly increased (P<0.05).No significant difference in the content of IL-1β and TNF-α in the CSF of normal control group, blank control group and medium dose group was observed, indicating that the model did not cause obvious inflammatory injury, and the modeling method was safe.Compared with blank control group, the contents of 5-HT, NE and Glu in the left hippocampus of rats in medium dose group were significantly increased (P<0.01), and the content of DA and ACh showed decreasing trends.The contents of 5-HT, NE and Glu in the right hippocampus of the rats were significantly increased (P<0.05), and the contents of DA and ACh showed decreasing trends.The content of Glu in cerebral cortex was significantly increased (P<0.05), the contents of 5-HT and NE showed increasing trends, and the contents of DA and ACh showed decreasing trends, indicating that the model was basically consistent with the pathological features of neurotransmitter imbalance in the brain of depression.CONCLUSION:This method can successfully replicate the rat model of depression, which has the characteristics of typical and persistent symptoms, fast modeling, and safe and easy operation.Using the dosage of 2 g/L is more suitable.

Study on Mechanism of Protective Effects of Baicalin on Male Rats with Ischemic Brain Injury / 中国中医药信息杂志

Objective To investigate the productive effects of baicalin on the male rats with ischemic brain injury and its effects on serum progesterone level in rats; To explore the possible mechanism of baicalin in brain protection. Methods Adult SD male rats were used to create a permanent left middle cerebral artery occlusion model. The rats were evenly divided into model group, baicalin group, inhibitor group, and sham-operation group (without inserted into the intraluminal thread) according to the neurological function scores. At different time points after modeling, the neurological function scores and the grip strength of double foreleg were measured, and the reduction rate of grip strength was calculated. Serum progesterone and adrenocorticotrophic hormone (ACTH) were detected by ELISA. Results Compared with the sham-operation group, the neurological function of rats in the model group was impaired, the grip strength of double foreleg was significantly reduced. 7 days after treatment, compared with the model group, the neurological function score of baicalin group was lowered, grip strength of double foreleg was recovered, reduction rate of grip strength was reduced (P<0.05); compared with the baicalin group, protective effects of baicalin on neurological function was lowered in inhibitor group (P<0.05). 7 days after treatment, compared with the model group, the serum progesterone level in baicalin group was significantly higher (P<0.01), and ACTH level showed an increasing trend; compared with the baicalin group, serum progesterone and ACTH levels in the inhibitor group decreased (P<0.05). Conclusion The protective effects of baicalin on the male rats with ischemic brain injury may be related to the regulation of progesterone.

Effect of nimodipine combined with 7.5％ hypertonic saline on postoperative cognitive function in aged rats / 中华麻醉学杂志

Objective To evaluate the effect of nimodipine combined with 7.5％ hypertonic saline (HS) on postoperative cognitive function in aged rats.Methods Ninety-six healthy male Wistar rats,aged 18 months,weighing 450-500 g,were assigned into 4 groups (n=24 each) using a random number table:splenectomy group (group S),nimodipine group (group N),group HS and nimodipine plus HS group (group N+HS).Nimodipine 1 mg/kg was intraperitoneally injected in group N.In group HS,7.5％ HS 4 ml/kg was injected via the caudal vein.The equal volume of normal saline was injected intraperitoneally or via the caudal vein in group S.Splenectomy was performed under sevoflurane anesthesia at 30 min after the end of administration.On 1 day before operation and 3 and 7 days after operation,Morris water maze test was performed,and blood sainples from the caudal vein were simultaneously collected for determination of the concentrations of serum S100β protein and neuron-specific enolase (NSE) by enzyme-linked immunosorbent assay.Results Compared with group S,the frequency of crossing the original platform was significantly increased,the escape latency was shortened,and the concentrations of serum S100β protein and NSE were decreased at each time point after operation in N,HS and N+HS groups (P＜0.05).Compared with group N or group HS,the frequency of crossing the original platform was significantly increased,the escape latency was shortened,and the concentrations of serum S100β protein and NSE were decreased at each time point after operation in group N+HS (P＜0.05).Conclusion Nimodipine combined with 7.5％ HS exerts better efficacy than either alone in improving postoperative cognitive function in aged rats.