双歧杆菌对门静脉血内毒素影响初步研究

本实验以大鼠为动物模型,探讨在肠道微生态失调的状态下,用大量双歧杆菌(Bifidobacteria)灌服,借以拮抗外源性需氧革兰氏阴性杆菌的生长繁殖,从而使肠源性内毒素自门静脉的吸收减少。对正常鼠、脱污染鼠、再污染鼠、治疗鼠和非治疗鼠,进行不同肠段的双歧杆菌、需氧革兰氏阴性杆菌的测定和门静脉血内毒素测定。结果表明:双歧杆菌对肠道需氧革兰氏阴性杆菌的生长繁殖,具有明显的生物拮抗作用,同时伴有相应的门静脉血内毒素水平的降低。     

大承气汤对MODS时肠道细菌微生态学影响的实验研究

目的探讨多器官功能不全综合征(MODS)大鼠肠道细菌微生态的变化及其与肠源性内毒素血症和细菌易位的关系,并观察大承气汤的影响。方法32只SD大鼠随机分成4组,对照组、模型组、大承气组和氨苄青霉素组。腹腔注射无菌酵母多糖A制备大鼠MODS模型。各组动物于造模后48 h无菌操作抽取外周静脉血和门静脉血进行内毒素含量测定;取肠系膜淋巴结进行细菌定量培养,取回肠和盲肠内容物进行肠腔内游离内毒素测定;取盲肠内容物进行肠道细菌微生态学分析。结果模型组外周血和门静脉血内毒素水平以及肠腔内游离内毒素含量均明显高于对照组(P<0.05);与对照组相比,模型组肠道菌群出现明显变化。肠球菌、肠杆菌数量明显增加,而双歧杆菌和乳酸杆菌数量出现显著下降,类杆菌数量亦出现明显下降(P<0.05)。模型组厌氧菌总数明显下降而需氧菌总数明显增加,同时厌氧菌总数/需氧菌总数的比值和B/E比值呈相应下降,发生倒置(P<0.05);正常对照组未发现肠道细菌向肠系膜淋巴结的易位,而模型组细菌易位阳性率是83.33%(P<0.05)。与模型组相比,大承气汤组上述各指标均出现明显变化(P<0.05);抗生素组作用不明显(P>0.05)。结论MODS时大鼠肠道细菌微生态出现明显变化,发生肠源性内毒素血症和细菌易位。大承气汤可以调整肠道菌群,恢复肠道微生态平衡,增加机体定植抗力,防治细菌易位和内毒素血症。     

双歧杆菌对实验性肠梗阻肠道G^—菌及血内毒素影响的研究

本实验采用大白鼠的急性、单纯性、机械性肠梗阻模型,将80只大鼠随机分成5组:正常对照组、梗阻未治疗组、新霉素治疗组、甲哨唑治疗组、双歧杆菌治疗组。分别将各制刑直接肠道给药。24h后,对梗阻近端回肠末段的肠杆菌、双歧杆菌进行定性及定量检测,并同时测定各组门静脉血内毒素值。结果表明,新霉素及甲哨唑治疗组双歧杆菌明显减少(P<0.01);门静脉血内毒素明显升高(P<0.01),达到未治疗组的水平(P<0.05)。新霉素治疗组肠杆菌明显减少(P<0.01),甲哨唑治疗组肠杆菌明显增加(P<0.01),达到未治疗组的水平(P>0.05)。未治疗组肠杆菌及门静脉血内毒素明显增加(P<0.01),双歧杆菌无明显减少。双歧杆菌治疗组双歧杆菌明显增加(P<0.01),肠杆菌保持在正常水平(P>0.05),门静脉血内毒素明显低于未治疗组和各抗生素治疗组(P<0.01)。本实验说明,急性肠梗阻时,肠道内肠杆菌数量及门静脉血内毒素可明显升高;外源性双歧杆菌在肠道内能抑制肠杆菌,降低门静脉血内毒素水平;新霉素及甲哨唑能引起肠道菌群紊乱,促使血内毒素过度升高。因此,利用双歧杆菌制剂作为急性肠梗阻治疗申的辅助用药,具有一定实际意义。     

双歧杆菌对菌群失调大鼠血清NO及NOS的影响

目的观察双歧杆菌对抗生素诱导的菌群失调大鼠血清一氧化氮(Nitricoxlcle,NO)及一氧化氮合成酶(Nitric oxide synthase,NOS)的影响。方法肠道盐酸林可霉素脱污染制备肠道菌群失调大鼠。造模成功后用双歧杆菌活菌灌胃治疗,14 d后血清学检测细胞因子NO、NOS水平。结果与模型组相比,NO含量明显增多(P<0.05);NOS含量降低(P<0.05)。结论双歧杆菌活菌可能通过调节细胞因子NO、NOS含量而调整菌群失调大鼠肠道内有益菌的比例。     

不同剂量长双歧杆菌对抗生素诱导大鼠肠道菌群失调的疗效观察

目的观察不同剂量长双歧杆菌对抗生素诱导大鼠腹泻及肠道菌群失调的调节作用。方法按体表面积予头孢曲松钠钠腹腔注射诱导大鼠腹泻及肠道菌群失调,然后灌胃不同剂量的长双歧杆菌菌粉,观察治疗后大鼠肠道菌群数量、B/E值和血清内毒素的变化。结果予头孢曲松钠钠处理后,大鼠肠道内双歧杆菌数量明显减少,肠球菌异常增殖,B/E值明显下降,血清内毒素升高,与对照组相比差异有统计学意义(P0.05)。高倍剂量治疗组肠道内细菌数量恢复程度及B/E值改善程度显著优于低倍剂量组。长双歧杆菌各治疗组的血清内毒素含量无明显改善,与自然恢复组之间无差异。结论头孢曲松钠可诱导大鼠肠道菌群失调。高倍剂量长双歧杆菌对头孢曲松钠所致肠道菌群失调效果更佳,短期应用不能明显改善头孢曲松钠诱发的内毒素血症。     

多器官功能不全综合征时肠道细菌微生态学改变的实验研究

为研究多器官功能不全综合征（ＭＯＤＳ）时肠道细菌微生态的变化以及Ｇ＾－杆菌消长与肠道和血液中内毒素水平的关系,本实验选用ＳＤ大鼠,应用无菌Ｚｙｍｏｓａｎ腹腔注射制备大鼠ＭＯＤＳ模型,并对ＭＯＤＳ大鼠肠道菌群进行定量分析,对门静脉和外周静脉血中的内毒以及肠道游离内毒素含量进行定量测定。结果发现,ＭＯＤＳ状态下肠道细菌微生态发生明显变化,表现为肠杆菌和肠球菌等肠道内需氧菌的数量明显增多,双歧杆菌和乳酸     

肠道菌群及内毒素在多器官功能不全综合征时的变化

目的　探讨肠道菌群及内毒素在多器官功能不全综合征( MODS)时的变化。方法　取SD大鼠,腹腔注射无菌酵母多糖A制备MODS模型,检测大鼠肠道菌群、外周血和门静脉血中的内毒素以及肠道游离内毒素含量,并进行定量分析。结果　模型组大鼠肠道专性厌氧菌的数量明显减少,革兰阴性杆菌和双歧杆菌的比例倒置,内毒素含量明显增加,与对照组比差异有显著性( P<0 .0 5 )。结论　MODS时肠道细菌微生态发生明显改变,肠道内毒素池与肠道革兰阴性杆菌的变化密切相关     

甲壳低聚糖的微生态学效应

目的 :了解甲壳低聚糖的微生态学效应 ,为其开发为微生态调节剂提供实验依据。方法 :用甲壳低聚糖〔6 0 0 m g/ (kg· d)〕给正常小鼠、肠道脱污染模型小鼠及 STZ糖尿病模型小鼠连续灌胃 7d及 2 1d,用添加 0 .3%甲壳低聚糖的高脂饲料为高血脂症大鼠模型连续灌胃 4 2 d。各空白对照组均用等体积无菌盐水灌胃。而后分析各组动物肠菌群 ,并测定 STZ糖尿病小鼠血糖、高血脂症大鼠 TC及 HDL- C值。结果 :甲壳低聚糖可以优化正常小鼠肠菌群 ,双歧杆菌数较空白对照组明显增多 (P<0 .0 5 ) ,B/ E值为对照组19.3倍 ,可纠正实验动物因肠道脱污染、糖尿病及高血脂症所致的肠菌群失调 ,双歧杆菌或乳杆菌相应增加 ,与相应空白对照组比较 ,其差异均有显著性意义 ,可以明显降低糖尿病小鼠血糖及高血脂症大鼠血清TC值。结论 :甲壳低聚糖具有良好的微生态学效应 ,可作为微生态调节剂开发应用     

大鼠肥胖抑郁模型建立及肠道菌群多样性的性别差异研究

目的 肥胖抑郁大鼠模型建立并对比研究肠道菌群多样性的变化。方法 采用高脂饲料喂养和CUMS经典造抑郁方法建立肥胖抑郁模型。将SD大鼠随机分为正常组(C组)、单纯肥胖组(F组)、单纯抑郁组(Y组)和肥胖抑郁组(FY组),整个造模持续5个月，通过糖水偏好实验、旷场实验和强迫游泳实验来评估大鼠抑郁样行为，检测模型鼠血清雌激素水平和血脂4项，并采集各组大鼠粪便样品，通过16S rDNA高通量测序法和生物信息分析软件分析测序结果，比较各组大鼠肠道菌群多样性的变化。结果 高脂饮食和CUMS方法成功制作肥胖抑郁鼠模型，肥胖和肥胖抑郁雌性大鼠雌激素水平明显升高，而雄性各组间雌激素水平无显著性差异。雌雄鼠的FY组肠道菌群α多样性具有显著差别，拟杆菌门和厚壁菌门B/F比值下降，且雄鼠肥胖抑郁B/F值只有雌鼠的一半左右。在属水平，研究结果表明雌雄鼠FY组和F组肠道菌群中Blautia等8个菌群变化一致，但是雌性与雄性在拟杆菌属等各有少量菌群的变化不一致。雌雄肥胖抑郁模型中，肠道菌群革兰氏阳性菌和阴性菌的组成出现差异，G⁺的构成，雌性和雄性均由由厚壁菌门和放线菌门构成，但构成比例不一样。...     

实验大鼠肝性病肠道菌群失调与血氨的关系

目的　探讨肝性脑病实验大鼠肠道菌群失调对血氨浓度的影响。方法　Wistar大鼠4 0只,随机分为4组,其中3组制备肝性脑病模型,剩余1组为正常对照组,分别以灌胃给药,以需氧、厌氧法及血浆除蛋白滤液法检测肠道菌群及血浆中血氨含量。结果　肝性脑病与正常对照组比较,有明显的肠道菌群失调症,同时伴有血氨浓度显著升高( P<0 .0 5 )。结论　实验大鼠肠道菌群失调可引起大鼠血浆内血氨浓度明显升高,进而引发肝性脑病及亚临床肝性脑病     

Levels of prostaglandin E1 and F2 alpha in the dynamics of toxic-infectious shock induced by Yersinia pestis

Murine toxin of Yersinia pestis when injected in the rat tail vein (LD50) caused pronounced alterations in PGE1 and PGF2 alpha content in different tissues (lung, heart, spleen, liver, kidney, small intestine) and blood. Heat-inactivated toxin has been shown to have the same effects as the intact toxin preparation. The changes in PG content are, probably, due to the lipopolysaccharide component of both preparations. The differences in metabolic effects between Yersinia pestis endotoxin and lipopolysaccharides of other Gram-negative bacteria are discussed.     

Intestinal microflora in rats under the conditions of a chronic toxic lesion of the liver

Intestinal microflora in healthy rats and its changes under the conditions of experimental chronic toxic hepatitis were studied. The study revealed that in intact animals the microflora of the small intestine was represented by bacteria of the genera Escherichia, Enterobacter, Moraxella, Alcaligenes, Staphylococcus, Streptococcus. Bacteria of the genera Escherichia, Enterobacter, Moraxella, Alcaligenes, Staphylococcus, Corynebacterium and Clostridium were isolated from the large intestine. No bacteria were found in the systemic blood, the contents of the portal vein, as well as in the liver parenchyma and the mesenterial lymph nodes. As the result of dysbiosis induced by the introduction of kanamycin and in chronic hepatitis caused by carbon tetrachloride the sharp decrease in the species composition of microbial communities (up to 2-3 species) in the small intestine and was observed along with penetration of bacteria into the blood stream, the mesenterial lymph nodes and the liver parenchyma. The tendency towards the restoration of the quantitative and qualitative microflora composition was noted following administration into experimental animals of bactisubtil and amixin--an inductor of interferonogenesis.     

Intestinal microbial patterns of the common marmoset and rhesus macaque

The intestinal microflora of common marmosets and rhesus monkeys were compared by enumerating bacteria from the small and large intestines. Rhesus monkeys had a consistent microflora pattern manifest by higher concentrations of total and Gram-negative aerobic and facultatively anaerobic bacteria, as well as aerobic and anaerobic Lactobacilli, in the large intestine as compared to the small intestine. In contrast, the marmoset microflora were considerably more variable. Approximately two-thirds of the marmosets (designated group A) had an overall profile that resembled the rhesus monkeys, but they had significantly higher concentrations of Gram-negative microflora in their large intestines than the rhesus monkeys. The remaining marmosets (group B) had higher concentrations of bacteria in the small intestine as compared to the large intestine, with the large intestinal concentrations being significantly lower than in the rhesus monkeys and group A marmosets. Moreover, the marmosets did not have detectable levels of aerobic Lactobacilli, and anaerobic Lactobacilli concentrations were significantly lower than in the rhesus macaques. Although it is unknown why microflora differ across species, it is likely that evolutionary adaptations in anatomy and functioning of the gastrointestinal tract influence the concentration and types of bacteria residing as the normal intestinal microflora.     

Effect of portal hypertension on splenic blood flow,intrasplenic extravasation and systemic blood pressure

We have previously shown that intrasplenic fluid extravasation is important in controlling blood volume. We proposed that, because the splenic vein flows in the portal vein, portal hypertension would increase splenic venous pressure and thus increase intrasplenic microvascular pressure and fluid extravasation. Given that the rat spleen has no capacity to store/release blood, intrasplenic fluid extravasation can be estimated by measuring the difference between splenic arterial inflow and venous outflow. In anesthetized rats, partial ligation of the portal vein rostral to the junction with the splenic vein caused portal venous pressure to rise from 4.5 +/- 0.5 to 12.0 +/- 0.9 mmHg (n = 6); there was no change in portal venous pressure downstream of the ligation, although blood flow in the liver fell. Splenic arterial flow did not change, but the arteriovenous flow differential increased from 0.8 +/- 0.3 to 1.2 +/- 0.1 ml/min (n = 6), and splenic venous hematocrit rose. Mean arterial pressure fell (101 +/- 5.5 to 95 +/- 4 mmHg). Splenic afferent nerve activity increased (5.6 +/- 0.9 to 16.2 +/- 0.7 spikes/s, n = 5). Contrary to our hypothesis, partial ligation of the portal vein caudal to the junction with the splenic vein (same increase in portal venous pressure but no increase in splenic venous pressure) also caused the splenic arteriovenous flow differential to increase (0.6 +/- 0.1 to 1.0 +/- 0.2 ml/min; n = 8). The increase in intrasplenic fluid efflux and the fall in mean arterial pressure after rostral portal vein ligation were abolished by splenic denervation. We propose there to be an intestinal/hepatic/splenic reflex pathway, through which is mediated the changes in intrasplenic extravasation and systemic blood pressure observed during portal hypertension.     

The effect of pancreatic and intestinal venous blood on hepatic atrophy and compensatory hyperplasia in the rat

Hepatotrophic effect of pancreatic and intestinal venous blood was studied in rats with mesocaval or distal splenocaval shunt following ligation of a branch of the portal vein supplying 70% of liver mass. Because 2/3 of liver mass was deprived of portal flow the nonligated liver lobes were not hypoperfused due to shunt procedure. During the first three postoperative days the DNA synthesis, mitotic index, and changes in relative weights were measured in both ligated (atrophied) and nonligated (compensatory hyperplasia) parts of the liver. It was found, that the restorative capacity of the liver existed in rats with selective portasystemic shunts. The stimulus to growth was greater in lobes supplied by intestinal venous blood compared to those perfused by pancreatic effluent. The increase in DNA synthesis occurred in lobes undergoing atrophy and the intensity of this response was also dependent on type of shunt since recirculation of intestinal blood by way of the hepatic artery inhibited atrophy to a greater extent than pancreatic venous effluent. Although the patency of arterial branches was confirmed the ligated lobes showed necrotic lesions. Systemic recirculation of intestinal venous blood far more inhibited necrosis than pancreatic venous blood.     

Role of acute elevation of portal venous pressure by exogenous glucagon on gastric mucosal injury in rats with portal hypertension

Time-course studies revealed the increased susceptibility of the gastric mucosa to noxious injury in portal hypertension correlates with the level of elevated portal venous pressure and hyperglucagonemia. Whether acute elevation of portal venous pressure by exogenous glucagon aggravates such injury is not known. We tested the hypothesis that glucagon in a dose sufficient to acutely elevate portal venous pressure aggravates noxious injury of the gastric mucosa in rats with portal hypertension. Infusion of a portal hypotensive dose of somatostatin should reverse these changes. In anesthetized rats with portal vein ligation, glucagon, somatostatin or the combination was administered intravenously in a randomized, coded fashion. Acidified ethanol-induced gastric mucosal injury was determined. Portal venous pressure and gastric mucosal perfusion and oxygenation (reflectance spectrophotometry) were monitored to confirm the effects of the respective intravenous treatments. Exogenous glucagon exacerbated acidified ethanol-induced gastric mucosal injury. The exacerbation was attenuated by somatostatin. These changes paralleled the portal hypertensive and hypotensive effects of glucagon and somatostatin, respectively. Our data suggest that a unique mechanism is triggered with the onset of portal hypertension. In an antagonistic manner, glucagon and somatostatin modulate this novel mechanism that controls portal venous pressure and susceptibility of the gastric mucosa to noxious injury.