Prevention by methylprednisolone of disseminated intravascular coagulation induced by sustained infusion of endotoxin in rats

An experimental model of disseminated intravascular coagulation (DIC) could be induced by a sustained infusion of 100 mg/kg of endotoxin for 4 h. Using this experimental model of DIC, the preventive effect of methylprednisolone against DIC was examined. Rats were injected with methylprednisolone at 0.1, 1.0, 10.0 or 30.0 mg/kg i.p., and thereafter infused continuously with 100 mg/kg/4 h of endotoxin. When compared with rats given no methylprednisolone, the significant prevention was noted in parameters, such as fibrinogen and fibrin degradation products, fibrinogen level, prothrombin time, partial thromboplastin time, platelet count, and the formation of fibrin thrombi in the glomeruli, in rats pretreated with 1.0, 10.0 or 30.0 mg/kg of methylprednisolone.     

Serum methylprednisolone levels following intra-articular injection of methylprednisolone acetate.

Twenty-one patients with rheumatoid arthritis received injections of either 40 mg or 80 mg of methylprednisolone acetate into one or both knee joints. Serum methylprednisolone and cortisol levels were measured at intervals up to 1 week following injection. Peak serum levels of methylprednisolone were reached at between 2 and 12 hours following injection, and increasing the injected dose resulted in correspondingly higher serum levels. Injection of 80 mg of methylprednisolone as 40 mg into each knee produced consistently higher peak serum levels than when given as a single intra-articular injection. Serum cortisol levels were substantially suppressed for up to 1 week, and this effect was seen at all dose levels.     

Postnatal development of rat lung following retarded fetal lung growth

Postnatal lung development was examined in rats born with smaller than normal lungs after either prenatal exposure to glucocorticoid or to an inhibitor of collagen synthesis. At birth, treated animals had lower than normal lung weights, lung to body weight ratios, hydroxyproline (HYP) levels, total DNA; and rates of DNA synthesis. Rats exposed to steroid showed a rapid recovery in growth during the normal postnatal cell proliferative phase from 4 to 11 days, though collagen levels did not return to normal until 3 weeks of age. Rats exposed to a prenatal proline analog showed a much slower rise in lung weight and total DNA, and these levels were still much below normal at 2-3 weeks when the cell proliferation phase was completed. Levels of disaturated phosphatidylcholine were significantly below normal up to 11 days, whereas total HYP was significantly reduced and less fibrillar collagen was seen in the lung throughout the study. The results indicate that the smaller but mature lungs at birth after antenatal steroid show a growth rebound and quickly become structurally normal. In contrast, inhibition of fibroblast growth and collagen deposition produces small lungs at birth, which continue to show inhibited growth and development at least up to 3 weeks of age, when the cell division phase is over.     

In vitro dopamine release from the rat striatum: diurnal rhythm and its modification by the estrous cycle

In the present experiment we examined spontaneous endogenous in vitro dopamine release from the corpus striatum of female rats during the morning (09.00-09.30 h) and afternoon (15.00-15.30 h) photoperiod on each day of the estrous cycle. In the morning, the spontaneous dopamine release rates of D-1, D-2 and proestrous female rats were characterized by initial low values which gradually increased (approximately 3-fold) over the 2.5-hour in vitro perifusion. In the afternoon, spontaneous release rates of D-1, D-2 and estrous females gradually declined (approximately 2.5-fold) over the perifusion period. This rhythmic diurnal fluctuation was disrupted in the afternoon of proestrus and morning of estrus when release rate profiles remained stable over the entire perifusion period. These results suggest that changes in spontaneous in vitro dopamine release of corpus striata derived from rats in different phases of the estrous cycle may reflect novel in vivo interactions of both photoperiodic and hormonal cues.     

Plasma concentrations of endotoxin following jugular or portal injections of endotoxin and following gastrointestinal ischemia due to hemorrhage

Endotoxin (LPS) was quantitated in canine plasma using the Limulus amebocyte lysate (LAL) chromogenic testing procedure. The assay was validated for sensitivity (25 pg/ml), recovery (90-110%), intra-assay precision (CV = 5.5), interassay precision (CV = 10), and stability of diluted, heat-treated, frozen samples (greater than or equal to 60 days). Canine plasma samples were analyzed for endotoxin following sublethal IV injections (cephalic and portal, bolus and slow infusion) of LPS. Pharmacokinetic analysis using the two-compartment open model on plasma LPS levels was possible for portal bolus, cephalic bolus, and portal slow infusion dogs. The results revealed that LPS given via cephalic bolus route had a lower clearance rate than LPS given via portal bolus route. Slow infusion of LPS into the portal vein revealed an increased distribution phase t1/2 in plasma and a slower elimination kel and beta rate than observed following a portal bolus injection of LPS. During a clinical endo(to)xemia, LPS enters the circulation slowly, and is therefore probably cleared more slowly; the prolonged low level of LPS may be responsible for many pathophysiological changes observed. Low levels of endotoxin were detected in plasma following hemorrhage, indicating that intestinal ischemia results in low levels of LPS leaking into the circulation.     

Role of prostanoids in experimental duodenal ulcer in rat

The purposes of this study were to determine whether inhibition of cyclooxygenase is a mechanism by which cysteamine and mepirizole produce duodenal ulcers, identify qualitative or quantitative differences in prostanoid production between gastric mucosa and duodenum, and determine whether differences in cyclooxygenase sensitivity to inhibition by aspirin exist between these two tissues. In fed female rats, gastric mucosal prostaglandin E₂ (PGE₂) and prostacyclin (PGI₂) generation was 235±25 and 832±40 ng/g/min, respectively, whereas full-thickness duodenal PGE₂ and PGI₂ generation was 665±46 and 662±49 ng/g/min, respectively. Over an intraperitoneal dose range of 0– 25 mg/kg, aspirin-induced cyclooxygenase inhibition was dose-dependent and similar for the two tissues. Duodenal ulceration (16.7 mm²) produced by cysteamine, 425 mg/kg, was associated with a 46% reduction in duodenal PGE₂ generation, while having no effect on PGI₂ generation; however, cysteamine, 213 mg/kg, produced no visible duodenal mucosa injury yet reduced duodenal PGE₂ generation 39% compared to control values. In fed male rats, gastric mucosal PGE₂ and PGI₂ generation was 179± 18 and 813± 61 ng/g/min, respectivley, whereas duodenal PGE₂ and PGI₂ generation was 321± 27 and 454± 38 ng/g/min, respectively. Duodenal ulceration (7.7 ± 2.3 mm²) produced by oral mepirizole was associated with a 63% reduction in duodenal PGE₂ generation compared to control values, while having no effect on PGI₂ generation. Subcutaneous aspirin, 100 mg/kg, which reduced duodenal PGE₂ generation to a greater degree than either ulcerogen, given in conjunction with pentagastrin, did not produce visible duodenal ulceration. It therefore seems unlikely that reduced PGE₂ generation within the duodenum is the primary mechanism of gross injury associated with these two ulcerogens.Supported by grant AM 17328 from NIADDK.     

Synergistic production of lung free radicals by diesel exhaust particles and endotoxin

The present study tested the hypothesis that free radicals were involved in the pathogenesis of lung injury caused by diesel exhaust particles (DEP) and bacterial lipopolysaccharides (LPS). Intratracheal coinstillation of DEP and LPS in rat lungs resulted in synergistic enhancement of free radical generation in the lungs. The radical metabolites were characterized as lipid-derived by electron spin resonance (ESR). The free radical generation was paralleled by a synergistic increase in total protein and by infiltration of neutrophils in the bronchoalveolar lavage (BAL) fluid of the lungs. Experiments with NADP-reduced (NADPH) oxidase and iNOS knockout mice showed that NADPH oxidase and iNOS did not contribute to free radical generation. However, pretreatment with the macrophage toxicant GdCl(3), the xanthine oxidase (XO) inhibitor allopurinol, and the Fe(III) chelator Desferal resulted in a marked decrease in free radical generation, lung inflammation, and lung injury. These effects were concomitant with the inhibition of XO activity in BAL, suggesting that the activated macrophages and the activity of XO contributed to the generation of free radicals caused by DEP and LPS. This is the first demonstration that DEP and LPS work synergistically to enhance free radical generation in lungs, mediated by the activation of local XO.     

Effects of repeated endotoxin injections on prostanoids, hemodynamics, endothelial cells, and survival in ponies

The objectives of this study were to determine the pathophysiological effects of increasing amounts of endotoxin administered intraperitoneally (IP) for 24 hr at which time an intravenous (IV) injection of endotoxin was given. The ability of flunixin meglumine (FM), a nonsteroidal antiinflammatory drug with antiprostaglandin activity, to provide protective effects was also determined. Eight ponies were divided into two groups of four ponies each; one group (untreated) received endotoxin only and the other group (treated) received endotoxin while being treated with flunixin. Hemodynamic and serum prostanoid changes were recorded for 26 hr during which time five IP and one IV endotoxin injections were given. Both groups behaved similarly until the intravenous endotoxin injection at 24 hr. At that time, the protective effects of flunixin became apparent by preventing increases in thromboxane and prostacyclin concentrations and by maintaining cardiac output, systemic arterial blood pressure, and blood flow to critical organs. Electron microscopic examination of pulmonary arteries of untreated animals revealed extensive endothelial cell damage while treatment with FM reduced this damage. A parallel study involving survival time in two groups of eight ponies each was also conducted using the same endotoxin and treatment protocol. At the end of 7 days, two of eight untreated ponies survived while six of eight treated ponies survived. It was concluded that FM prevented the release of prostanoids, maintained hemodynamics and blood flow nearer pre-endotoxin values, reduced vascular endothelial cell damage, and improved survival.     

Respiratory health and endotoxin: associations and modification by CD14/-260 genotype

Exposure to endotoxin has been associated with increased respiratory symptoms and decrements in lung function in occupational settings but little is known about the health effects of domestic exposure in adults. Here, we describe the association of respiratory disease, immunoglobulin (Ig)E sensitisation, bronchial reactivity and lung function with mattress endotoxin levels in adults, and determine whether these associations are modified by polymorphisms in CD14. Endotoxin levels in mattress dust from a population-based sample of 972 adults were measured. Associations were examined using generalised linear mixed models, adjusting for individual and household confounders. Effect modification of these associations by CD14/-260 (rs2569190) was assessed. Mattress endotoxin levels varied from 0.1 to 402.6 EU · mg(-1). Although there was no overall association of lung function with endotoxin exposure, there was evidence that the association of forced expiratory volume in 1 s and forced vital capacity with endotoxin was modified by CD14/-260 genotype (p-value for interaction 0.005 and 0.013, respectively). There was no evidence that symptoms, IgE sensitisation or bronchial reactivity were associated with mattress endotoxin levels. In this large epidemiological study of adults, there was no evidence that mattress endotoxin level was associated with respiratory symptoms or IgE sensitisation but the association of lung function with endotoxin levels may be modified by CD14 genotype.     

甲基强的松龙诱导大鼠胸腺淋巴细胞凋亡的研究

目的 探讨大剂量甲基强的松龙（ＭＰ）诱导大鼠胸腺淋巴细胞凋亡作用的存在。方法 采用流式细胞仪技术,琼脂糖凝胶电泳等方法对细胞凋亡状态进行检测。结果 大剂量ＭＰ注于大鼠体内后,可诱导大鼠胸腺淋巴细胞进入凋亡状态,注入后６ｈ,无明显细胞凋亡,１２ｈ后出现凋亡改变,２４ｈ凋亡细胞改变明显增加,连续用药２￣３ｄ,虽凋亡细胞比率增加,但与用药２４ｈ相比,差异无显著性。结论甲基强的松龙体内注射后,以用药后２４     

Evaluation of lung injury and respiratory mechanics in a rat model of acute pancreatitis complicated with endotoxin

BackgroundAcute lung injury (ALI) is a common complication of acute pancreatitis (AP) and contributes to the majority of AP-associated deaths, particularly in the setting of secondary infection. This ‘two-hit’ model mimics clinical cases where the presentation of AP is associated with mild lung injury that, following a secondary direct lung infection, can result in respiratory dysfunction and death. We therefore aimed to characterize lung injury in a clinically-relevant ‘two-hit’ rat model of caerulein-induced AP combined with intratracheal endotoxin.MethodsRats received 7 hourly intraperitoneal injections of caerulein (50 μg/kg). Twenty four hours following the first caerulein injection, rats were anaesthetised and LPS (15 mg/kg) was instilled intratracheally. Following LPS instillation, rats were ventilated for a total of 2 h.ResultsIn the present study, AP results in mild pulmonary injury indicated by increased lung myeloperoxidase (MPO) activity and edema, but with no alteration of respiratory function, while intratracheal instillation of LPS results in more substantial pulmonary injury. The induction of AP challenged with secondary intratracheal LPS results in an exacerbation of lung damage indicated by further increased lung edema, plasma and bronchoalveolar (BAL) CINC-1 concentration, lung damage histology score, and lung tissue resistance and elastance, compared with LPS alone.ConclusionsIn conclusion, the addition of instilled LPS acted as a “second-hit” and exacerbated caerulein-induced AP, compared with the induction of AP alone or the instillation of LPS alone. Given its clinical relevance, this model could prove useful for examination of therapeutic interventions for ALI following secondary infection.     

Adrenergic stimulation of renal prostanoids in the Lyon hypertensive rat

Young, genetically hypertensive Lyon (LH) rats exhibited an increased renal in vivo turnover of norepinephrine and an elevated urinary excretion of thromboxane B2 when compared with normotensive (LN) and low blood pressure (LL) controls. Therefore, the effects of norepinephrine (1.2 x 10(-8) to 9.6 x 10(-7) M) and of phenylephrine (5 x 10(-8) to 1.9 x 10(-6) M) on renal function and the urinary excretion of prostanoids were assessed in isolated perfused kidneys of 8-week-old LH, LN, and LL rats. In addition, the effects of norepinephrine were assessed before and during thromboxane A2/prostaglandin H2 receptor blockade by AH23848 (4 x 10(-6) M). Before drug infusion, LH kidneys differed from those of LN and LL controls by having an elevated renal vascular resistance and a decreased natriuresis and glomerular filtration rate; the urinary output of prostaglandin E2 and F2 alpha, of 6-ketoprostaglandin F1 alpha, and of thromboxane B2 was similar in the three strains. The constrictor effects of norepinephrine and phenylephrine were significantly increased in LH rat kidneys compared with LL but not with LN controls, and their pressure-natriuresis was markedly reduced. Norepinephrine and phenylephrine induced a 10- to 20-fold dose-dependent increase in the synthesis of the four prostanoids, which was more pronounced in LH than in LN and LL rats for thromboxane B2 only. AH23848 infusion significantly reduced the vascular effects of norepinephrine and increased the natriuretic response of LH but not of LN and LL rat kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased sheep lung vascular permeability caused by Escherichia coli endotoxin.

We infused Escherichia coli endotoxin, 0.07-1.33 microgram/kg, intravenously into chronically instrumented unanesthetized sheep and measured pulmonary arterial and left atrial pressures, lung lymph flow, lymph and blood plasma protein concentrations, and arterial blood gases. Endotoxin caused a biphasic reaction: an early phase of pulmonary hypertension and a long late phase of steady state increased pulmonary vascular permeability during which pulmonary arterial and left atrial pressures were not increased significantly and lung lymph flow was 5 times the baseline value. Lymph: plasma total protein concentration ratio during the late phase (0.76 +/- 0.04) was significantly (P less than 0.05) higher than during baseline (0.66 +/- 0.03). The lymph response was reproducible. Lung lymph clearance of endogenous proteins with molecular radii (r) 35.5 to 96 A was increased during the steady state late phase of the reaction, but, as during baseline, clearance decreased as r increased. The endotoxin reaction was similar to the reaction to infusing whole Pseudomonas bacteria, except that endotoxin had less effect on pressures during the steady state response and caused a relatively larger increase in lymph clearance of large proteins. We conclude that E. coli endotoxin in sheep causes a long period of increased lung vascular permeability and may have a greater effect on large solute pathways across microvessels than do Pseudomonas bacteria.     

Renal microthrombosis following endotoxin infusion may be mediated by lipoxygenase products

Renal microvascular thrombosis following endotoxin infusion was assessed by measuring accumulation of 125I-labeled fibrinogen and transmission electron microscopy. Endotoxin shock was induced in unanesthetized Sprague-Dawley rats using 14 mg/kg Escherichia coli endotoxin (Difco) infused intravenously over a 5-hour period. Fifteen minutes after infusion of endotoxin was started, intravenous treatment was initiated. Two-thirds of the treatment was given over a period of 20 minutes followed by the remaining dose over the next 2 hours. Five rats received methyl prednisolone sodium succinate (Solu-Medrol) (U-9,088) (39.5 mg/kg). Six rats received a Solu-Medrol analog (methyl prednisolone 21(N-Methyltaurosuberate), sodium salt) (U-67,590A) (61.08 mg/kg). Six rats received a 5-lipoxygenase inhibitor (1-naphthalenol,2,3,diethyl-4-methoxy-acetate) (U-66,855) (20 mg/kg). Six rats received a prostacyclin analog (pentanoic acid, 5- less than hexahydro-5-hydroxy-6-(3-hydroxy-1-octenyl)-3a-methyl-2(1H)- pentalenylidene greater than -calcium salt, hydrate) (U-61,431F) (0.04 mg/kg). Six rats received a thromboxane synthase inhibitor (2-benzofurancarboxylic acid, 5-(3-pyridinylmethyl), sodium salt monohydrate) (U-63,557A) (18 mg/kg). Eight endotoxin-infused rats received only normal saline. Six control rats received no endotoxin infusion, only saline. Composition and location of thrombi were assessed by transmission electron microscopy. Glomerular thrombosis was quantitated by determination of whole blood equivalents of 125I fibrin/g of tissue. Electron microscopy and radioactive quantitation demonstrated microthrombosis in the nontreated endotoxin group. The thrombi contained fibrin, platelets, erythrocytes, and leukocytes. The extent of thrombosis was significantly elevated compared to saline-treated controls. Three treated groups (U-9,088, U-67,590A, and U-66,855) all had significantly less thrombosis than the nontreated endotoxin rats. Two treated groups (U-63,557A and U-61,431F) developed glomerular thrombosis similar to untreated endotoxin rats. The results suggest that endotoxin stimulation of procoagulant activity and microthrombosis may be mediated by production of arachidonic acid metabolites via the lipoxygenase pathway.     

Deposition and clearance of fibrin in the rat lung following acute haemorrhage

The effect of acute haemorrhage on the deposition and clearance of fibrin in the rat lung after thrombin-induced intravascular coagulation was investigated. Haemorrhage was followed by less embolization of fibrin to the lungs and delayed elimination from the lungs. As lung tissue fibrinolysis was not diminished, the peripheral and pulmonary circulatory disturbance was probably in itself responsible for the observed effects.     

单甲氧基聚乙二醇对大鼠胰岛的免疫修饰作用

目的:研究单甲氧基聚乙二醇(mPEG 5000)对Wistar大鼠胰岛表面抗原的掩蔽作用及对胰岛素分泌功能的影响．方法:分离Wistar大鼠的胰岛,对照组不进行任何处理,处理组分别用200,300,400 g／L mPEG包裹,培养24 h后分别用双硫腙染色检测胰岛细胞活性、葡萄糖刺激实验检测胰岛的分泌功能改变,取SD大鼠脾淋巴细胞分别与上述各组胰岛进行混合培养,通过杀伤实验检测胰岛免疫原性．结果:与对照组相比,不同浓度mPEG包裹对大鼠胰岛活性及胰岛素分泌功能无明显影响,不同浓度处理组的胰岛细胞杀伤率均明显低于对照组(24．7％,14．8％,21．4％vs 69．5％, t=2.378,2．584,2．472,P均<0．05),但300 g／L mPEG处理组的杀伤率最低(14．8％vs 24．7％, 21．4％,t=2.285,2．383,P均<0．05)．结论:mPEG有效掩蔽大鼠胰岛表面抗原,且不影响胰岛细胞的活性及胰岛素分泌功能,具有较好的免疫修饰作用．