不同压力氧气对大鼠潜水减压病的预防作用

目的:研究不同压力氧气对大鼠减压病的预防作用。方法:40只雄性SD大鼠,随机分为减压病组、1 ATA预吸氧组、2 ATA预吸氧组、3 ATA预吸氧组。减压病组置于脱险舱内,以"压缩空气3 min内匀速加压至0.7 MPa,停留60 min后,3 min内匀速减压"方案处理后出舱。预吸氧组分别于进舱前吸不同压力的氧20 min后再按上述方案加减压出舱。出舱后30 min内观测大鼠死亡率、行为学改变;取大鼠肺组织,测其干湿重比、支气管肺泡灌洗液蛋白量以及肿瘤坏死因子(TNF-α)表达含量变化。结果:和减压病组比较,预吸氧对减压病的死亡率及发病率无明显影响。但1 ATA预吸氧组大鼠支气管肺泡灌洗液蛋白量和炎症因子TNF-α值下降明显,肺干湿重比升高明显(P0.05)。结论:预吸氧对减压病的死亡率及发病率无明显改善,但是常压吸氧可减轻存活大鼠肺泡灌洗液中蛋白渗透、降低肺组织中炎症因子的表达。     

高压氧预处理对减压病大鼠肺组织的影响

目的:研究高压氧预处理对减压病大鼠肺组织的影响及其意义。方法:SD大鼠30只,随机分为正常对照(CN)组,高压氧预处理(HBO)组,减压(DCS)组,减压组采用20min匀速升压至7.0ATA,停留20min使大鼠充分换气,2min内快速减压常压方案。减压24h后观察肺组织中谷胱甘肽过氧化物酶(GPx)、丙二醛(MDA)、超氧化物歧化酶(SOD)的变化;并通过HE染色观察肺组织病理学变化。结果:减压组肺泡腔不够完整,肺泡破裂融合,肺泡壁增厚,有中度炎性细胞浸润,高压氧组与减压组相比,病理改变明显减轻;与对照组相比,单纯减压使大鼠肺组织GPx、MDA升高,SOD降低,高压氧预处理组GPx、MDA降低,SOD降低升高;高压氧组与减压组相比GPx、MDA下降,SOD升高(P<0.05)。结论:高压氧预处理对减压病大鼠肺组织具有一定的保护作用。     

核辐射对大深度快速上浮脱险致减压病大鼠相关指标的影响*

目的: 探讨不同剂量核暴露后不同时间对大深度快速上浮脱险致减压病大鼠模型的发病率、死亡率及损伤指标的影响。方法: 80只SD雄性大鼠,随机分成空白对照组、脱险对照组和6个干预组(4 Gy辐射后4 h脱险、6 Gy辐射后4 h脱险、12 Gy辐射后4 h脱险、4 Gy辐射后8 h脱险、6 Gy辐射后8 h脱险、12 Gy辐射8 h后脱险),每组10只。干预组动物先采用不同剂量γ射线外照射(4、6、12 Gy),再进行大深度快速上浮脱险实验(最大加压深度150 m),分析大鼠肺W/D、脾指数及血浆IL-1β的变化。结果: 与脱险对照组比较,核辐射后脱险大鼠的减压病发病率及死亡率明显上升。4 Gy、6 Gy照射4 h后上浮脱险的大鼠发病率和死亡率较照射8 h后高。12 Gy辐射后4 h及8 h脱险大鼠的减压病的发病率及死亡率均比低剂量照射组明显增高,死亡率尤其明显。和发病率及死亡率的变化相一致,肺组织湿/干比、肺组织病理损伤程度、脾指数下降也表现同样的变化趋势:较低剂量(4 Gy、6 Gy)辐射后4 h改变明显,8 h改变不明显,而高剂量(12 Gy)辐射后4、8 h均变化明显。和空白对照组及脱险对照组相比较,各辐射后脱险组的血浆IL-1β浓度均显著上升。结论: 核辐射引起放射性肺损伤、免疫功能下降及血浆炎症因子浓度升高,会增加大鼠快速上浮脱险致减压病的风险。     

肠淋巴再灌注加重肠系膜上动脉闭塞性休克大鼠肺部炎症反应

目的:研究肠系膜淋巴再灌注对肠系膜上动脉闭塞性(SMAO)休克大鼠肺部炎症反应的影响。方法:24只Wistar雄性大鼠均分为4组:SMAO组,MLR组,SMAO+MLR组,SHAM组。再灌注2h后,迅速留取肺组织,一部分制备组织匀浆,检测细胞间粘附分子(ICAM-1)和晚期糖基化产物受体(RAGE)。再另外选取固定位置肺部组织放入中性甲醛中固定,用于测定肺内HMGB1、RAGE的表达。结果:SMAO与SMAO+MLR组肺部组织匀浆ICAM-1、RAGE含量显著高于MLR与SHAM组,且SMAO+MLR组肺组织匀浆的ICAM-1、RAGE含量高于SMAO组。肺部组织内HMGB1和RAGE在MLR组与SHAM组基本不表达,或少量表达,MLR加重了SMAO休克模型中HMGB1和RAGE的表达。结论:MLR加重SMAO休克大鼠肺部炎症反应,进一步证实肠淋巴途径在SMAO休克发病学中具有重要作用,同时证实HMGB1及RAGE在SMAO休克大鼠的炎症失常反应中起重要作用。     

溶栓前后肺血栓栓塞症大鼠肺血管内皮细胞ICAM-1及Ps的表达

目的观察溶栓前后肺血栓栓塞症(pulmonarythromboembolism,PTE)大鼠肺血管内皮细胞上细胞间粘附分子-1(intercellularadhesion-1,ICAM-1),P-选择素(P-selectin,Ps)的变化,以此探讨溶栓治疗的影响。方法采用自体血栓回输法建立PTE模型,随机分为对照组、模型组、溶栓组。各组动物在栓塞后1、3、24、72、120h5个时间段分别处死,进行病理切片,免疫组化和原位杂交的方法检测肺血管内皮细胞上ICAM-1和Ps的蛋白及mRNA的变化。结果肺栓塞后病理可见肺动脉血栓形成,炎性反应明显。肺血管内皮上ICAM-1蛋白及mRNA表达在栓塞后3h开始增高(P<0·01),而Ps蛋白及mRNA表达在栓塞后1h开始增高(P<0·01)。溶栓治疗后,栓塞、出血、萎缩减轻,但炎性反应有所加重,肺血管内皮上ICAM-1和Ps的水平再次升高(P<0·01)。结论细胞间粘附分子-1与P-选择素均参与了大鼠肺血栓栓塞症的发病过程,溶栓治疗并未改善肺组织的炎性损伤。     

高压氧预处理对急性减压所致的大鼠肺组织细胞凋亡及Bcl-2/Bax表达的影响

目的:探讨高压氧预处理对减压病大鼠肺组织细胞凋亡的影响相关蛋白表达的影响。方法:雄性SD大鼠24只,随机分为3组,正常对照组(NC group)、HBO预处理组(HBOP group)、减压组(DCS group),每组8只。连续进行HBO预处理5天后进行减压病模型制备,取左侧肺组织进行湿干重比值测定,右侧肺组织用于病理实验;HE染色观察肺组织病理学改变,免疫组织化学法标记Bcl-2、Bax、Caspase-3与MMP-9阳性细胞表达,并对bcl-2/bax值进行分析。结果:减压组肺组织Bax、Caspase-3与MMP-9阳性细胞数明显增加(P0.05),而Bcl-2阳性细胞表达减少(P0.05);高压氧预处理组与减压组相比,Bax、Caspase-3与MMP-9阳性细胞数明显减少(P0.05),而Bcl-2阳性细胞表达增加(P0.05);大鼠肺组织减压组与高压氧预处理组Bcl-2/Bax值较对照组明显降低(P0.05);与减压组相比,高压氧预处理组明显升高(P0.05)。结论:HBO预处理可以减轻减压对肺组织的病理损伤,减轻肺泡和支气管上皮细胞的变性坏死,抑制细胞凋亡,从而起到对减压病的保护作用。     

480米氦氧饱和潜水时粘附分子及腺苷的表达变化

目的:探讨480m氦氧饱和潜水时潜水员体内粘附分子、环磷酸腺苷(cAMP)及环磷酸鸟苷(cGMP)的表达改变。方法:4名潜水员经氦氧混合气加压至饱和深度480m,饱和逗留期间巡潜到493m。高压暴露时间共约447 h,其中加压96 h,饱和逗留49 h,减压302 h。分别在进舱前及出舱后抽取静脉血,ELISA法测定血清中的细胞间黏附分子-1(ICAM-1)、E-选择素(E-selectin)、P-选择素(P-selectin)、L-选择素(L-selectin)、cAMP、cGMP的表达变化。结果:和基础值比较,480 m饱和潜水后各潜水员血清中ICAM-1、P-selectin、E-selectin、L-selectin、cGMP均无显著改变,但cAMP由进舱前(66.72±83.15)nmol/L增高为(629.91±75.01)nmol/L(P<0.05)。结论:480 m氦氧饱和潜水减压程序是安全的,未引起减压障碍的病理生理的改变,但引起机体应激反应增强。     

肠淋巴再灌注加重肠系膜上动脉闭塞性休克大鼠肺部炎症反应

目的：研究肠系膜淋巴再灌注对肠系膜上动脉闭塞,Ig（SMAO）休克大鼠肺部炎症反应的影响。方法：24只Wistar雄性大鼠均分为4组：SMAO组,MLR组,SMAO＋MLR组,SHAM组。再灌注2h后,迅速留取肺组织,一部分制备组织匀浆,检测细胞间粘附分子（ICAM-1）和晚期糖基化产物受体（RAGE）。再另外选取固定位置肺部组织放入中性甲醛中固定,用于测定肺内HMGB1、RAGE的表达。结果-SMAO与SMAO＋MLR组肺部组织匀浆ICAM-1、RAGE含量显著高于MLR与SHAM组．且SMAO＋MLR组肺组织匀浆的ICAM-1、RAGE含量高于SMAO组。肺部组织内HMGB1和RAGE在MLR组与SHAM组基本不表达,或少量表达,MLR加重了SMAO休克模型中HMOB1和RAGE的表达。结论：MLR加重SMAO休克大鼠肺部炎症反应．进一步证实肠淋巴途径在SMAO休克发病学中具有重要作用,同时证实HMGB1及RAGE在SMAO休克大鼠的炎症失常反应中起重要作用。     

芹菜素对缺血再灌注大鼠心肌核转录因子-κB和ICAM-1表达的影响

目的研究芹菜素对缺血再灌注大鼠心肌核转录因子-κB(NF-κB)和粘附分子ICAM-1表达的影响,探讨其抗心肌缺血再灌注损伤的可能机制。方法将Wistar大鼠随机分为6组:假手术组、缺血再灌注组(IR组)、溶剂对照组、维拉帕米阳性对照组、芹菜素低、高剂量用药组。采用结扎左冠状动脉前降支制作缺血再灌注模型,心肌缺血30 min,再灌注2 h。免疫组化染色检测心肌组织的NF-κB和ICAM-1的表达.结果芹菜素组可降低心肌组织NF-κB和ICAM-1的表达,与IR组比较有显著差异(P0.05)。结论芹菜素对缺血再灌注心肌的保护作用可能与其减少心肌缺血再灌注后NF-κB和ICAM-的激活有关。     

内皮素-1在神经源性肺水肿中的作用

目的:探讨内皮素-1(ET-1)在神经源性肺水肿(NPE)发病机理中的作用.方法:采用Marmarous 闭合性颅脑损伤模型致大鼠重度、弥漫性颅脑损伤,检测血浆、肺匀浆中ET-1的含量,并用免疫组化方法检测肺ET-1的表达.结果:大鼠重度弥漫性颅脑损伤后1 h起血浆及肺匀浆中ET-1含量增加,6 h达高峰,24 h以后略有下降,但是,在48 h内一直维持在较高水平(P<0.05).病理学检查显示:伤后1h起肺毛细血管扩张、充血;肺间隔增宽,有以中性粒细胞及单个核细胞为主的白细胞浸润,6 h最明显;24 h、48 h肺充血、肿胀,肺泡腔内充满大量嗜伊红的蛋白渗出物.免疫组化显示:ET-1在实验组较对照组阳性表达增强,光密度值增高,以6 h最显著.结论:ET-1介导的炎性损伤机制在神经源性肺水肿中可能起重要作用.     

Natural history of severe decompression sickness after rapid ascent from air saturation in a porcine model.

We developed a swine model to describe the untreated natural history of severe decompression sickness (DCS) after direct ascent from saturation conditions. In a recompression chamber, neutered male Yorkshire swine were pressurized to a predetermined depth from 50-150 feet of seawater [fsw; 2.52-5.55 atmospheres absolute (ATA)]. After 22 h, they returned to the surface (1 ATA) at 30 fsw/min (0.91 ATA/min) without decompression stops and were observed. Depth was the primary predictor of DCS incidence (R = 0.52, P < 0.0001) and death (R = 0.54, P < 0.0001). Severe DCS, defined as neurological or cardiopulmonary impairment, occurred in 78 of 128 animals, and 42 of 51 animals with cardiopulmonary DCS died within 1 h after surfacing. Within 24 h, 29 of 30 survivors with neurological DCS completely resolved their deficits without intervention. Pretrial Monte Carlo analysis decreased subject requirement without sacrificing power. This model provides a useful platform for investigating the pathophysiology of severe DCS and testing therapeutic interventions. The results raise important questions about present models of human responses to similar decompressive insults.     

Acclimatization to neurological decompression sickness in rabbits

Diving acclimatization refers to a reduced susceptibility to acute decompression sickness (DCS) in individuals undergoing repeated compression-decompression cycles. We demonstrated in a previous study that the mechanism responsible for this acclimatization is similar to that of stress preconditioning. In this study, we investigated the protective effect of prior DCS preconditioning on the severity of neurological DCS in subsequent exposure to high pressure in rabbits. We exposed the rabbits (n = 10) to a pressure cycle of 6 absolute atmospheres (ATA) for 90 min, which induced signs of neurological DCS in 60% of the animals. Twenty-four hours after the pressure cycle, rabbits with DCS expressed more heat-shock protein 70 (HSP70) in the lungs, liver, and heart than rabbits without signs of disease or those in the control group (n = 6). In another group of rabbits (n = 24), 50% of animals presented signs of neurological DCS after exposure to high pressure, with a neurological score of 46.5 (SD 19.5). A course of hyperbaric oxygen therapy alleviated the signs of neurological DCS and ensured the animals' survival for 24 h. Experiencing another pressure cycle of 6 ATA for 90 min, 50% of 12 rabbits with prior DCS preconditioning developed signs of DCS, with a neurological score of 16.3 (SD 28.3), significantly lower than that before hyperbaric oxygen therapy (P = 0.002). In summary, our results show that the occurrence of DCS in rabbits after rapid decompression is associated with increased expression of a stress protein, indicating that the stress response is induced by DCS. This phenomenon was defined as "DCS preconditioning." DCS preconditioning attenuated the severity of neurological DCS caused by subsequent exposure to high pressure. These results suggest that bubble formation in tissues activates the stress response and stress preconditioning attenuates tissue injury on subsequent DCS stress, which may be the mechanism responsible for diving acclimatization.     

Short oxygen prebreathing and intravenous perfluorocarbon emulsion reduces morbidity and mortality in a swine saturation model of decompression sickness.

Disabled submarine (DISSUB) survivors will achieve inert gas tissue saturation within 24 h. Direct ascent to the surface when saturated carries a high risk of decompression sickness (DCS) and death, yet may be necessary during rescue or escape. O(2) has demonstrated benefits in decreasing morbidity and mortality resulting from DCS by enhancing inert gas elimination. Perfluorocarbons (PFCs) also mitigate the effects of DCS by decreasing bubble formation and increasing O(2) delivery. Our hypothesis is that combining O(2) prebreathing (OPB) and PFC administration will reduce the incidence of DCS and death following saturation in an established 20-kg swine model. Yorkshire swine (20 +/- 6.5 kg) were compressed to 5 atmospheres (ATA) in a dry chamber for 22 h before randomization into one of four groups: 1) air and saline, 2) OPB and saline, 3) OPB with PFC given at depth, 4) OPB with PFC given after surfacing. OPB animals received >90% O(2) for 9 min at depth. All animals were returned to the surface (1 ATA) without decompression stops. The incidence of severe DCS < 2 h after surfacing was 96%, 63%, 82%, and 29% for groups 1, 2, 3, and 4, respectively. The incidence of death was 88%, 41%, 54%, and 5% for groups 1, 2, 3, and 4, respectively. OPB combined with PFC administration after surfacing provided the greatest reduction in DCS morbidity and mortality in a saturation swine model. O(2)-related seizure activity before reaching surface did not negatively affect outcome, but further safety studies are warranted.     

Decompression sickness in the rat following a dive on trimix: recompression therapy with oxygen vs. heliox and oxygen.

Trimix (a mixture of helium, nitrogen, and oxygen) has been used in deep diving to reduce the risk of high-pressure nervous syndrome during compression and the time required for decompression at the end of the dive. There is no specific recompression treatment for decompression sickness (DCS) resulting from trimix diving. Our purpose was to validate a rat model of DCS on decompression from a trimix dive and to compare recompression treatment with oxygen and heliox (helium-oxygen). Rats were exposed to trimix in a hyperbaric chamber and tested for DCS while walking in a rotating wheel. We first established the experimental model, and then studied the effect of hyperbaric treatment on DCS: either hyperbaric oxygen (HBO) (1 h, 280 kPa oxygen) or heliox-HBO (0.5 h, 405 kPa heliox 50%-50% followed by 0.5 h, 280 kPa oxygen). Exposure to trimix was conducted at 1,110 kPa for 30 min, with a decompression rate of 100 kPa/min. Death and most DCS symptoms occurred during the 30-min period of walking. In contrast to humans, no permanent disability was found in the rats. Rats with a body mass of 100-150 g suffered no DCS. The risk of DCS in rats weighing 200-350 g increased linearly with body mass. Twenty-four hours after decompression, death rate was 40% in the control animals and zero in those treated immediately with HBO. When treatment was delayed by 5 min, death rate was 25 and 20% with HBO and heliox, respectively.     

Effect of CP-96,345 on the expression of adhesion molecules in acute pancreatitis in mice

We investigated the effect of a specific neurokinin-1 receptor (NK1R) antagonist, CP-96,345, on the regulation of the expression of adhesion molecules ICAM-1, VCAM-1, E-selectin, and P-selectin as well as leukocyte recruitment during acute pancreatitis (AP). AP was induced in male Balb/C mice by 10 consecutive hourly intraperitoneal injections of caerulein. In the treatment groups, CP-96,345 was administered at 2.5 mg/kg ip either 30 min before or 1 h after the first caerulein injection. Animals were killed, and the lungs and pancreas were isolated for RNA extraction and RT-PCR or for immunohistochemical staining. mRNA expression of the four adhesion molecules was upregulated in the pancreas during AP. Treatment with CP-96,345 effectively reduced the mRNA expression of P-selectin and E-selectin but not ICAM-1 and VCAM-1. In the lung, ICAM-1, E-selectin, and P-selectin mRNA expression increased during AP. Antagonist treatment suppressed this elevation. Similar expression patterns were seen in the immunohistochemical stainings. Intravital microscopy of the pancreatic microcirculation revealed the effect of CP-96,345 on leukocyte recruitment. The present study provides important information on the relationship between NK1R activation and the regulation of adhesion molecules. Also, this study points to the differential regulation of inflammation in the pancreas and lung with AP.     

Leukocyte and endothelial cell adhesion molecules in a chronic murine model of myocardial reperfusion injury

Expression of endothelial and leukocyte cell adhesion molecules is a principal determinant of polymorphonuclear neutrophil (PMN) recruitment during inflammation. It has been demonstrated that pharmacological inhibition of these molecules can attenuate PMN influx and subsequent tissue injury. We determined the temporal expression of alpha-granule membrane protein-40 (P-selectin), endothelial leukocyte adhesion molecule 1 (E-selectin), and intercellular cell adhesion molecule 1 (ICAM-1) after coronary artery occlusion and up to 3 days of reperfusion. The expression of all of these cell adhesion molecules peaked around 24 h of reperfusion. We determined the extent to which these molecules contribute to PMN infiltration by utilizing mice deficient (-/-) in P-selectin, E-selectin, ICAM-1, and CD18. Each group underwent 30 min of in vivo, regional, left anterior descending (LAD) coronary artery ischemia and 24 h of reperfusion. PMN accumulation in the ischemic-reperfused (I/R) zone was assessed using histological techniques. Deficiencies of P-selectin, E-selectin, ICAM-1, or CD18 resulted in significant (P < 0.05) attenuation of PMN infiltration into the I/R myocardium (MI/R). In addition, P-selectin, E-selectin, ICAM-1, and CD18 -/- mice exhibited significantly (P < 0.05) smaller areas of necrosis after MI/R compared with wild-type mice. These data demonstrate that MI/R induces coronary vascular expression of P-selectin, E-selectin, and ICAM-1 in mice. Furthermore, genetic deficiency of P-selectin, E-selectin, ICAM-1, or CD18 attenuates PMN sequestration and myocardial injury after in vivo MI/R. We conclude that P-selectin, E-selectin, ICAM-1, and CD18 are involved in the pathogenesis of MI/R injury in mice.     

Expression of adhesion molecules during cadmium hepatotoxicity

Inflammatory processes play a major role in the secondary injury of the liver produced by cadmium (Cd), and infiltration of neutrophils at the site of necrosis is a common observation. Although the infiltration of leukocytes (mainly neutrophils) into sites of injuried tissue within liver during Cd toxicity is mediated by adhesion molecules, little is known about expression of these adhesion molecules during Cd hepatotoxicity. In the present study, the expression of E-, P-selectin, intracellular adhesion molecule-1 (ICAM-1) and platelet-endothelial adhesion molecule-1 (PECAM-1) was analyzed by immunohistochemistry and immunofluoresence during Cd-induced hepatotoxicity in male rats. In contrast to E-, and P-selectin, ICAM-1 and PECAM-1 were constitutively expressed on sinusoidal endothelial cells of control liver. However, P-selectin was not induced within the liver by Cd administration, whereas E-selectin expression was induced in the liver with a marked increase in immunostaining on sinusoidal endothelial cells from 12 h to 7 days. Also, there was an upregulation in ICAM-1 immunostaining on sinusoidal endothelial cells from 12 h to 7 days after Cd administration, whereas there was no obvious change of PECAM-1 immunostaining on sinusoidal endothelial cells until 24 h. However, PECAM-1 expression was markedly decreased at 48 h but significantly increased at 7 days after Cd administration compared to control liver. Taken together, upregulation of E-selectin and ICAM-1 with biphasic changes in PECAM-1 expression within liver after Cd administration suggests an important role for these adhesion molecules during Cd hepatoxicity.