一氧化氮对细菌性肺炎大鼠炎症介质的影响

目的探讨吸入一氧化氮(NO)对肺炎克雷白杆菌肺炎大鼠肺部炎症介质的影响。方法健康大鼠随机分为肺炎组(P)和正常对照(C)组,P组气道注入肺炎克雷白杆菌(约1.3×108cfu只),然后分组(n=8～10)干预24h:吸入空气(PA)、NO(20×10-6,PNO)、低氧(FiO20.4,PLO)、低氧加NO(PLONO)、高氧(FiO21.0,PHO),高氧加NO(PHONO);C组吸入空气(CA)或NO(CNO)。测定肺组织原生型和诱生型NO合酶(cNOS和iNOS)活性,肿瘤坏死因子α(TNFα)和细胞间黏附分子1(ICAM1)蛋白水平及mRNA表达。结果PA组iNOS活性显著高于CA组(P<0.01),cNOS活性显著低于CA组(P<0.01);PNO、PLO、PLONO、PHO及PHONO组均可使被抑制的cNOS活性增强,PHO及PHONO可抑制iNOS活性增加;TNFα水平PA和PHONO组均显著高于CA组(P<0.01),PNO、PLO和PLONO组均显著低于PA组(P<0.01);ICAM1水平PA组显著高于CA组(P<0.01),PNO、PLONO和PHONO组分别低于PA、PLO和PHO组(P<0.01)。各组肺组织TNFα、ICAM1、内皮细胞型NOS和iNOSmRNA表达差异均无显著性。结论吸入NO和或氧气对肺炎大鼠肺内cNOS及iNOS活性具有不同调节作用;吸入NO可抑制肺组织ICAM1表达;吸入NO和或低浓度氧可降低TNFα表达。吸入NO可能通过调节急性炎症反应介质预防炎症性肺损伤。     

Effects of inhaled nitric oxide in a mouse model of sepsis-induced acute lung injury

OBJECTIVE: Although inhaled nitric oxide transiently improves oxygenation in patients with acute lung injury, it has not affected clinical outcomes. As well, the effects of inhaled nitric oxide on the pathophysiologic features of acute lung injury have not been well defined. Therefore, we assessed the effects of inhaled nitric oxide on the degree of pulmonary inflammation and injury in a mouse model of sepsis-induced acute lung injury. DESIGN: Randomized, controlled animal study. SETTING: Research laboratory of an academic institution. SUBJECTS: Male C57Bl/6 mice. INTERVENTIONS: Sepsis was induced by cecal ligation and perforation. At the time of surgery, septic and na?ve mice were randomized to exposure to either 40 ppm inhaled nitric oxide or room air for 24 hrs before they were killed. MEASUREMENTS AND MAIN RESULTS: Sepsis-induced acute lung injury was characterized by increased pulmonary myeloperoxidase (68 +/- 13 vs. 13 +/- 3 mU/mg protein in na?ve mice, p <.01), pulmonary 8-isoprostane content (627 +/- 51 vs. 88 +/- 20 pg/mg protein in na?ve mice, p <.01), and protein in bronchoalveolar lavage fluid (p <.05). Inhaled nitric oxide exposure in septic mice completely abrogated the septic increases in myeloperoxidase activity (p <.05) and pulmonary 8-isoprostane content (p <.05) but had no effect on bronchoalveolar lavage protein. The induction of sepsis also was associated with an increase in pulmonary inducible NO synthase activity (2.8 +/- 0.5 vs. 0.4 +/- 0.1 pmol small middle dotmin-1 small middle dotmg-1 protein in na?ve mice, p <.05), and inhaled nitric oxide attenuated this increase in pulmonary inducible NO synthase activity (p <.05). CONCLUSIONS: Exposure to inhaled nitric oxide early in the course of sepsis-induced acute lung injury is associated with reduced pulmonary leukocyte infiltration and less oxidative injury. Decreased lung inflammation and injury with inhaled nitric oxide is associated with decreased pulmonary inducible NO synthase activity. Therefore, inhaled NO may have greater clinical benefit if administered earlier in the natural history of acute lung injury in patients.     

Effects of inhaled nitric oxide on pulmonary hemodynamics in a porcine model of endotoxin shock.

OBJECTIVE: To evaluate the effects of inhaled nitric oxide (NO) on pulmonary circulation in a porcine endotoxin shock model. DESIGN: Prospective, randomized trial. SETTING: Laboratory at a large university medical center. SUBJECTS: Twelve pathogen-free pigs weighing 15 to 31 kg. INTERVENTIONS: After surgical preparation, all pigs received a 0.5 mg/kg endotoxin infusion over 30 mins. One hour after the start of endotoxin, NO inhalation (40 ppm) was initiated in six pigs, whereas the six remaining pigs served to control the progression of shock in this model. Consecutive changes in systemic and pulmonary hemodynamics, including characteristic resistance, vascular compliance, peripheral vascular resistance, and inductance, were continuously assessed during the experimental protocol using a four-element Windkessel model of the pulmonary circulation. MEASUREMENTS AND MAIN RESULTS: Endotoxin insult resulted in a biphasic pulmonary artery pressure increase from 14 +/- 2 to 32 +/- 4 mm Hg. Inhaled NO reversed the resistance to blood flow in small pulmonary arteries from 596 +/- 69 to 424 +/- 36 dyne-sec/ cm5. In contrast, the vascular capacitance of the entire pulmonary circuit, which decreased from 2.4 +/- 0.2 to 0.8 +/- 0.1 mL/mm Hg throughout endotoxin challenge, remained insensitive to NO administration. CONCLUSION: In endotoxin-induced pulmonary hypertension, inhaled NO may function as a modulator of distal pulmonary arterial tone but fails to act as a regulator of larger capacitance pulmonary vessels.     

Saturability of granulocyte kill of Pseudomonas aeruginosa in a murine model of pneumonia

Outcomes for patients with dense bacterial burdens, such as ventilator-associated pneumonia (VAP) patients, are often critically influenced by the adequacy of antimicrobial chemotherapy and by the response of the immune system, particularly the granulocytes. Little information is available about the quantitation of kill of organisms over time by granulocytes. In this investigation, we examined the impact of the baseline bacterial burden on the ability of granulocytes alone (without chemotherapy) to keep the number of organisms in check or to kill them over a 24-h period. Pseudomonas aeruginosa ATCC 27853 was the study organism, and we employed a murine pneumonia model (granulocyte replete) for the study. We found that the ability of the immune system to kill P. aeruginosa was saturable. The burden at which the system was half saturated was 2.15 × 10⁶ ± 2.66 × 10⁶ CFU/g. Burdens greater than 10⁷ CFU/g demonstrated net growth over 24 h. These findings suggest the need for aggressive chemotherapy early in the treatment of VAP to keep the burden from saturating the granulocytes. This should optimize the outcome for these seriously infected patients.     

Effects of parenterally administered ciprofloxacin in a murine model of pulmonary Pseudomonas aeruginosa infection mimicking ventilator-associated pneumonia.

BACKGROUND AND METHODS: We compared the bacteriological, pharmacological and histopathological effects of parenterally administered ciprofloxacin (CPFX) to those of imipenem/cilastatin (IMP/CS) and cefozopran (CZOP) in a murine model of mucoid Pseudomonas aeruginosa pneumonia mimicking ventilator-associated pneumonia. RESULTS: The minimum inhibitory concentrations (MICs) of CPFX, IMP and CZOP were 1.0, 1.0 and 4.0 mg/l, respectively. Treatment with CPFX resulted in a significant decrease in the number of viable bacteria [control, IMP/CS, CZOP and CPFX (mean +/- SEM): 5.02 +/- 0.20, 4.96 +/- 0.38, 5.44 +/- 0.13 and 3.27 +/- 0.02 log(10) colony-forming units lung, respectively]. Histopathological examination revealed that inflammatory changes in the CPFX-treated group were less marked than in other groups. Of the drugs analyzed, the pharmacokinetic parameters of area under the time-concentration curve (AUC)/MIC, AUC exceeding MIC and the time that lung concentrations of drug remained above the MIC were highest for CPFX. CONCLUSION: Our results suggest that parenterally administered ciprofloxacin is effective in ventilator-associated P. aeruginosa pneumonia.     

Effects of inhaled nitric oxide on regional blood flow are consistent with intravascular nitric oxide delivery.

Nitric oxide (NO) may be stabilized by binding to hemoglobin, by nitrosating thiol-containing plasma molecules, or by conversion to nitrite, all reactions potentially preserving its bioactivity in blood. Here we examined the contribution of blood-transported NO to regional vascular tone in humans before and during NO inhalation. While breathing room air and then room air with NO at 80 parts per million, forearm blood flow was measured in 16 subjects at rest and after blockade of forearm NO synthesis with N(G)-monomethyl-L-arginine (L-NMMA) followed by forearm exercise stress. L-NMMA reduced blood flow by 25% and increased resistance by 50%, an effect that was blocked by NO inhalation. With NO inhalation, resistance was significantly lower during L-NMMA infusion, both at rest and during repetitive hand-grip exercise. S-nitrosohemoglobin and plasma S-nitrosothiols did not change with NO inhalation. Arterial nitrite levels increased by 11% and arterial nitrosyl(heme)hemoglobin levels increased tenfold to the micromolar range, and both measures were consistently higher in the arterial than in venous blood. S-nitrosohemoglobin levels were in the nanomolar range, with no significant artery-to-vein gradients. These results indicate that inhaled NO during blockade of regional NO synthesis can supply intravascular NO to maintain normal vascular function. This effect may have application for the treatment of diseases characterized by endothelial dysfunction.     

Pathogenesis of septic shock in Pseudomonas aeruginosa pneumonia

The pathogenesis of septic shock occurring after Pseudomonas aeruginosa pneumonia was studied in a rabbit model. The airspace instillation of the cytotoxic P. aeruginosa strain PA103 into the rabbit caused a consistent alveolar epithelial injury, progressive bacteremia, and septic shock. The lung instillation of a noncytotoxic, isogenic mutant strain (PA103DeltaUT), which is defective for production of type III secreted toxins, did not cause either systemic inflammatory response or septic shock, despite a potent inflammatory response in the lung. The intravenous injection of PA103 did not cause shock or an increase in TNF-alpha, despite the fact that the animals were bacteremic. The systemic administration of either anti-TNF-alpha serum or recombinant human IL-10 improved both septic shock and bacteremia in the animals that were instilled with PA103. Radiolabeled TNF-alpha instilled in the lung significantly leaked into the circulation only in the presence of alveolar epithelial injury. We conclude that injury to the alveolar epithelium allows the release of proinflammatory mediators into the circulation that are primarily responsible for septic shock. Our results demonstrate the importance of compartmentalization of inflammatory mediators in the lung, and the crucial role of bacterial cytotoxins in causing alveolar epithelial damage in the pathogenesis of acute septic shock in P. aeruginosa pneumonia.     

吸入一氧化氮对内毒素性肺损伤大鼠肺磷脂合成的影响

目的　探讨吸入 2 0× 10 - 6 (V /V )浓度一氧化氮 (NO)气体对大鼠内毒素性肺炎症损伤时磷脂酰胆碱 (PC)合成代谢的影响。方法　成年大鼠先随机分为接受静脉注射内毒素 (LPS)和对照组(C) ,2 4h后再随机给予吸空气 (Air)、 95 %氧气 (O2 )、 2 0× 10 - 6 NO加空气 (NO)、 2 0× 10 - 6 NO加 95 %氧气 (O2 NO)干预。采用氚标记氯化胆碱掺入法 ,测大鼠合成PC能力。Weinhold法测肺组织磷酸胆碱二胞苷酰基转移酶 (CCT)的活性。结果　在干预后 4h ,NO组LPS大鼠肺组织 (LT)及支气管肺泡灌洗液(BALF)中总磷脂 (TPL)及饱和磷脂酰胆碱 (DSPC)放射活性小于其他各组 (P <0 0 1) ,CCT活性小于其他各组 (P <0 0 1)。在干预后 2 4h ,O2 组LPS大鼠LT及BALF中TPL及DSPC放射活性小于其他各组 (P <0 0 1) ,CCT活性、BALF中TPL含量、DSPC/TP均显著低于其他干预下的LPS大鼠 (P <0 0 1及P <0 0 5 )。结论　针对炎症损伤肺 ,吸入 2 0× 10 - 6 浓度的NO 2 4h不会对磷脂酰胆碱合成代谢产生持续影响 ,并能拮抗高氧对磷脂合成的抑制作用。     

Delivery and monitoring of inhaled nitric oxide

Inhaled nitric oxide is rapidly gaining popularity as a selective pulmonary vasodilator in patients with acute lung injury and pulmonary hypertension. The development of nitric oxide as a drug has bypassed the usual regulatory and commercial processes, and as a result clinicians have devised a wide range of delivery and monitoring systems. This review describes these systems, and discusses their advantages, disadvantages and safety. The monitoring of nitric oxide metabolites is also discussed.     

重症监护病房铜绿假单胞菌肺部感染患者的危险因素分析

目的分析重症监护病房(ICU)肺炎患者铜绿假单胞菌(PA)感染及死亡的危险因素,为临床控制肺炎患者PA感染提供依据。方法回顾性分析2008年4月1日至2012年3月31日入住ICU的PA感染患者102例,非PA感染患者102例,PA感染患者中肺炎患者86例,非PA感染患者中肺炎患者73例,采用单因素及多因素Logistic回归分析PA肺炎感染的危险因素。结果年龄、入ICU时APACHEⅡ评分、住ICU天数、是否建立人工气道、呼吸机使用时间是PA肺炎发生的独立危险因素,是否多重耐药是PA肺炎死亡的独立危险因素。结论患者高龄、病情重、机械通气、住ICU及机械通气时间长是ICU患者PA感染的独立危险因素,多重耐药是PA肺炎患者死亡的独立危险因素。     

一氧化氮吸入对脓毒症幼猪血流动力学和氧合功能的影响

目的：研究脓毒症幼猪吸入一氧化氮（N0）后心脏指数（CI）与氧合指数的变化。方法：静脉注入革兰氏阴性杆菌内毒素（LPS）诱导脓毒症幼猪模型。随机分为两组：NO组（n＝8）为脓毒症模型建立后,在容量控制通气基础上持续吸入80 ppmNO 30 min;对照组（n＝4）为脓毒症模型建立后单纯容量控制通气,观察30 min以确定模型的稳定性并与NO组比较。利用脉波指示剂连续心排血量监测（PICC0）技术和动脉血气分析,测定各组血流动力学参数和肺气体交换。结果：静脉注射内毒素能够诱导稳定的脓毒症幼猪模型。该模型血气分析指标pH、HCO3－、股动脉血氧分压（PaO2）、平均动脉压（MAP）及心脏指数（CI）均较基础值明显降低（P＜0．01）。NO组PaO2及CI均较吸入前和同时点对照组明显升高（P＜0．01）。NO组及对照组心率（HR）、中心静脉压（CVP）、全心舒张末容积指数（GEDI）及胸腔内血容积指数（ITBI）均无明显变化。结论：吸入NO气体可以改善脓毒症幼猪的心功能及氧合功能。     

Effects of inhaled nitric oxide on lung injury after intestinal ischemia-reperfusion in rats

Splanchnic ischemia/reperfusion (I/R) induces a systemic inflammatory response with acute lung injury. Impaired production of endothelial nitric oxide (NO) plays a key role in this process. We evaluated the effects of early treatment with inhaled NO (iNO) on lung microcirculatory inflammatory changes during splanchnic I/R. I/R was induced in rats by occlusion of the superior mesenteric artery (SMA; 40 min) and reperfusion (90 min). Four groups were studied: Control, anesthesia only; Sham, all surgical procedures without I/R, ventilated with air; Air, SMA I/R, ventilation with air; and NO, SMA I/R, ventilation with NO (20 ppm) starting 10 min before reperfusion. Intravital video microscopy was used to monitor pulmonary macromolecular flux and capillary flow velocity (CFV). Leukocyte infiltration was determined by morphometry. SMA I/R decreased mean arterial blood pressure, capillary CFV (P < 0.01), and shear rate (P < 0.01), and increased pulmonary macromolecular leak by 138% +/- 8% (P < 0.001). iNO markedly attenuated the increase in macromolecular leak (P < 0.01), blunted the decrease in capillary CFV (P < 0.05) and shear rate (P < 0.05), and prevented the increase in leukocyte infiltration of the lungs after SMA I/R (P < 0.05). The direct, real-time, in vivo data suggest that early institution of low-dose iNO therapy effectively ameliorates the acute remote pulmonary inflammatory response after splanchnic I/R.     

Therapeutic effects of a human antiflagella monoclonal antibody in a neutropenic murine model of Pseudomonas aeruginosa pneumonia.

Human immunoglobulin G1 (IgG1) monoclonal antibodies (MAbs) reactive with type-specific Pseudomonas aeruginosa lipopolysaccharide (LPS) and flagella were compared for their protective activities against Fisher immunotype 2 P. aeruginosa pneumonia in neutropenic mice. The activity of the antiflagella MAb at a dose of 500 micrograms per mouse was comparable to that of the anti-LPS MAb at the same dose. In vivo protection was correlated with bacterial density in the lung tissue and blood of infected mice. In vitro data suggested that the protective activity of the antiflagella MAb was due more to inhibition of bacterial motility than to opsonophagocytosis of bacteria by alveolar macrophages. In contrast, the protective activity of the anti-LPS MAb was primarily related to alveolar macrophage-mediated opsonophagocytosis. Antiflagella MAb at a dose of 500 micrograms combined with oral sparfloxacin at a subtherapeutic dose of 62.5 micrograms produced a significant increase in survival (P < 0.05) compared with that produced by either agent alone or no treatment. The additive effects between the antiflagella MAb and sparfloxacin at sub-MICs on the inhibitory effects of bacterial motility supported the in vivo effect of the combination. These data suggest that human isotype-matched antiflagella and anti-LPS MAbs have similar protective activities against Pseudomonas pneumonia in neutropenic mice, despite discrete mechanisms of antibody-matched protection. In addition, in vivo synergy was demonstrated between antiflagella MAb and sparfloxacin in this model.     

In vivo efficacy and pharmacokinetics of biapenem in a murine model of ventilator-associated pneumonia with Pseudomonas aeruginosa

Biapenem (BIPM) has high bactericidal activity against Pseudomonas aeruginosa and similar activity in vitro as meropenem (MEPM). We used a murine model to examine the efficacy of biapenem against ventilator-associated pneumonia (VAP) caused by P. aeruginosa. Mice were treated by intraperitoneal injection with 100 mg/kg BIPM or MEPM every 12 h beginning 12 h after inoculation with P. aeruginosa. Survival was evaluated for 7 days, and 24 h after infection, lung histopathology was analyzed and the number of viable bacteria in the lungs and blood was counted. In addition, the pharmacokinetics of BIPM and MEPM were analyzed after the initial treatment. BIPM and MEPM significantly prolonged survival compared to control (P < 0.05). The lungs of mice treated with BIPM or MEPM had significantly fewer viable bacteria (3.54 ± 0.28 vs. 3.77 ± 0.14 log(10) CFU/ml) than in the lungs of control mice (6.65 ± 0.57 log(10) CFU/ml) (P < 0.05). Furthermore, viable bacteria were not detected in the blood of mice treated with BIPM or MEPM (control 2.85 ± 0.85 log(10) CFU/ml) (P < 0.05). Histopathological examination of lung specimens indicated that BIPM and MEPM prevent the progression of lung inflammation, including alveolar neutrophil infiltration and hemorrhage. The % time above MIC for BIPM and MEPM was 15.4% and 18.3% in plasma and 19.8% and 19.8% in lungs, respectively. These results show that BIPM and MEPM significantly prolongs survival and reduces the number of viable bacteria in a murine model of VAP caused by P. aeruginosa. Therefore, BIPM might be a potent and effective treatment for VAP caused by this bacterium.     

捕食应激对大鼠海马一氧化氮及神经型一氧化氮合酶的影响

目的探讨一氧化氮(NO)在创伤后应激障碍(PTSD)样行为异常大鼠的变化规律,以进一步揭示PTSD的神经生物学机制。方法将144只Wistar大鼠随机分组为捕食应激组(n=72)及正常对照组(n=72),在大鼠捕食应激PTSD动物模型基础上,动态检测大鼠海马、额叶皮层组织匀浆NO、一氧化氮合酶(NOS)含量及神经元型NOS(nNOS)表达。结果应激大鼠海马NO含量于捕食应激后即刻明显高于对照组犤(2.8±0.8)μmol/g,F=23.112,P=0.000犦,12h达高峰(3.9±1.1)μmol/g,与对照组比较,F=56.616,P=0.000;与同组其他时相比较,F=14.917,P<0.05,24h时仍明显增多犤(2.6±0.7)μmol/g,F=23.094,P=0.000犦;海马nNOS表达亦同步增高(应激后即刻,12及24h,F=14.228,21.772,18.500,P<0.01),而海马总NOS活性仅在应激后12h内增高犤应激后即刻及12hNOS分别为(9.8±2.5)mmol/(s·kg),F=32.812,P=0.000及(10.2±2.7)mmol/(s·kg),F=31.395,P=0.000犦。结论严重心理/生理应激所致海马nNOS持续性高表达与NO释放明显增多,在实验大鼠持续性PTSD样行为异常中可能有重要作用。     

Effects of intratracheal administration of novispirin G10 on a rat model of mucoid Pseudomonas aeruginosa lung infection

Chronic Pseudomonas aeruginosa lung infection is a major problem for patients with cystic fibrosis (CF). The biofilm mode of growth of the pathogen makes it highly resistant to antibiotic treatment, and this is especially pronounced with mucoid strains. In this study, novispirin G10, a synthetic antimicrobial peptide patterned loosely on sheep myeloid antimicrobial peptide 29, was tested in a rat model of mucoid P. aeruginosa lung infection. P. aeruginosa NH57388A, a mucoid strain isolated from a CF patient, was mixed with the alginate produced by the bacterium itself and adjusted to a concentration of 10(10) CFU/ml. Each rat received 10(9) CFU of bacteria intratracheally in the left lung to establish lung infection. At 0 and 3 h post P. aeruginosa infection, the treated group of rats received novispirin G10 (0.1 mg/ml, 0.1 ml/rat) intratracheally, whereas the control group received vehicle treatment only. The animals were sacrificed on days 3, 5, 7, and 10 after challenge for evaluation of various parameters. On day 5, 50% of the rats in the treated group had cleared the bacteria from the lungs, whereas in the control group, none of the rats cleared the pathogen (P < 0.03). The average bacterial loads remaining in the lungs of treated rats on days 3 and 5 were more than 170- and 330-fold lower than in the control groups (P < 0.0005 and P < 0.0003). In accordance, the macroscopic and microscopic lung pathology was also significantly milder in the treated group compared to the control group (P < 0.0002). Lung cytokine responses in the treated group were significantly lower than in the control group. The results suggest that novispirin G10 might be useful in treating antibiotic-resistant P. aeruginosa lung infections.