Chronic treatment with the glucocorticoid receptor antagonist RU486 inhibits diabetes-induced enhancement of experimental periodontitis.

BACKGROUND AND OBJECTIVE: Chronic hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and excessive glucocorticoid hormone release have been associated with diabetes, altered immune responses and increased susceptibility to periodontitis. In the present study we tested the impact of streptozotocin (STZ)-induced diabetes on ligature-induced periodontitis and the effect of subsequent treatment with the glucocorticoid receptor (GR) antagonist, RU486. MATERIAL AND METHODS: A single dose of STZ [45 mg/kg, intraperitoneally (i.p.)] or vehicle was given 10 d before induction of ligature-induced periodontitis and implantation subcutaneously of a drug pellet containing the GR antagonist, RU486, or a placebo pellet. Periodontitis was assessed when the ligatures had been in place for 21 d. Two hours before decapitation all rats received gram-negative bacterial lipopolysaccharide (LPS) (150 µg/kg, i.p.) to induce a robust immune and stress response. RESULTS: Compared with control rats, STZ-treated rats developed significantly more periodontal bone loss, and RU486 treatment of STZ -treated rats significantly inhibited this effect. STZ-treated rats also showed significantly higher levels of the HPA axis-derived hormone, corticosterone, as well as of the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-α), but lower levels of the anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor-1beta (TGF-1ß) after LPS stimulation. GR blockade had no statistically significant effects on these measurements in diabetic rats, but tended to enhance the levels of TNF-α and TGF-1ß, and reduce the levels of IL-10 and blood glucose. CONCLUSION: In diabetic subjects, excessive GR activation as a result of chronic high levels of glucocorticoid hormones may alter immune-system responses in a manner that may increase the susceptibility to periodontitis.

Oral treatment with complement factor C5a receptor (CD88) antagonists inhibits experimental periodontitis in rats.

BACKGROUND AND OBJECTIVE: The complement activation product 5a (C5a) is a potent mediator of the innate immune response to infection, and may thus also importantly determine the development of periodontitis. The present study was designed to explore the effect of several novel, potent and orally active C5a receptor (CD88) antagonists (C5aRAs) on the development of ligature-induced periodontitis in an animal model. MATERIAL AND METHODS: Three different cyclic peptide C5aRAs, termed PMX205, PMX218 and PMX273, were investigated. Four groups of Wistar rats (n = 10 in each group) were used. Starting 3 d before induction of experimental periodontitis, rats either received one of the C5aRas (1-2 mg/kg) in the drinking water or received drinking water only. Periodontitis was assessed when the ligatures had been in place for 14 d. RESULTS: Compared with control rats, PMX205- and PMX218-treated rats had significantly reduced periodontal bone loss. CONCLUSION: The findings suggest that complement activation, and particularly C5a generation, may play a significant role in the development and progression of periodontitis. Blockade of the major C5a receptor, CD88, with specific inhibitors such as PMX205, may offer novel treatment options for periodontitis.

Severe gunshot injuries in a porcine model: impact on central markers of innate immunity.

BACKGROUND: the mechanisms behind lipopolysaccharide (LPS) tolerance remain obscure. LPS signals through Toll-like receptor 4 (TLR4) and severe trauma/haemorrhage may influence binding and signalling through this receptor, e.g. by changing membrane expression or by releasing endogenous ligands like High Mobility Group Box 1 (HMGB1). The aim of this study was to examine these relations further in a porcine model with standardized trauma. METHODS: nine anaesthetized pigs sustained one gunshot through the femur and one pistol shot through the upper abdomen. Blood was sampled before and 90 min after shooting. The samples were stimulated for 4 h with LPS 10 ng/ml or an equivalent amount of normal saline. The leucocyte response was evaluated by measuring the tumour necrosis factor-α (TNF-α) and CXC ligand 8 (CXCL8) in the supernatant. Flow cytometry was used to measure the surface expression of TLR4 on CD14+ monocytes. HMGB1 concentrations were measured in the plasma. RESULTS: trauma and treatment caused a significant decline in the LPS-stimulated concentrations of TNF-α [4.53 ± 0.24 pg/ml (ln) at 0 min, 3.54 ± 0.35 pg/ml (ln) at 90 min, P=0.026], but did not modify the release of CXCL8. Monocyte TLR4 expression was unchanged. Plasma HMGB1 increased significantly [<0.92 vs. 3.02 ± 0.19 ng/ml (ln), P<0.001]. The concentrations of TNF-α and CXCL8 did not correlate with TLR4 expression or HMGB1 concentrations. CONCLUSION: the results suggest that trauma-induced LPS tolerance is not primarily regulated by TLR4 expression on circulating CD14+ monocytes or by the release of HMGB1 from damaged tissues.

Nicotinic acetylcholine receptor activation mediates nicotine-induced enhancement of experimental periodontitis.

BACKGROUND AND OBJECTIVE: Smokers have an increased risk of developing periodontitis as well as showing more rapid progression and resistance to treatment of the disease, but the biological mechanisms are poorly understood. Our objective was to investigate putative biological mechanisms by which nicotine may enhance the susceptibility and thus the course of periodontitis in an animal model. MATERIAL AND METHODS: Ligature-induced periodontitis was applied in periodontitis-susceptible Fischer 344 rats. The animals were given daily intraperiotonal (i.p.) injections of the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine (1 mg/kg) 45 min before subcutaneous (s.c.) injections in the neck skin with nicotine (0.8 mg/kg), or treated with the same amount of saline i.p. and nicotine s.c., or with mecamylamine and saline. Control rats received i.p. and s.c. injections of saline only. Periodontal bone loss was assessed when the ligatures had been in place for 3 weeks. Two hours before decapitation, all rats received lipopolysaccharide (LPS; 100 microg/kg, i.p.) to induce a robust immune and stress response. RESULTS: Compared with saline/saline-treated control rats, saline/nicotine-treated rats developed significantly more periodontal bone loss, and LPS provoked a significantly smaller increase in circulating levels of the cytokines tumour necrosis factor alpha (TNF-alpha), transforming growth factor 1beta (TGF-1beta) and interleukin-10 (IL-10). Mecamylamine pretreatment of nicotine-treated rats abrogated the increased periodontal bone loss and the LPS-induced TNF-alpha decrease, but had no significant effects on the levels of TGF-1beta and IL-10, or the stress hormone corticosterone. CONCLUSION: The results indicate that nicotine enhances susceptibility to periodontitis via nAChRs, which may act via suppressing protective immune responses through the cholinergic anti-inflammatory pathway.

Nicotinic acetylcholine receptor activation mediates nicotine-induced enhancement of experimental periodontitis.

BACKGROUND AND OBJECTIVE: Smokers have an increased risk of developing periodontitis as well as showing more rapid progression and resistance to treatment of the disease, but the biological mechanisms are poorly understood. This study was designed to investigate putative biological mechanisms by which nicotine may enhance the susceptibility and thus the course of periodontitis in an animal model. MATERIAL AND METHODS: Ligature-induced periodontitis was applied in periodontitis-susceptible Fischer 344 rats. The animals were either given daily intraperitoneal injections of the nicotinic acetylcholine receptor antagonist mecamylamine (1 mg/kg) 45 min before subcutaneous injections in the neck skin of nicotine (0.8 mg/kg), or treated with the same amount of saline intraperitoneally and nicotine subcutaneously, or treated with mecamylamine and saline. Control animals received intraperitoneal and subcutaneous injections of saline only. Periodontal bone loss was assessed when the ligatures had been in place for 3 wk. Two hours before decapitation, all rats received lipopolysaccharide (LPS; 100 microg/kg, intraperitoneally) to induce a robust immune and stress response. RESULTS: Compared with saline/saline-treated control animals, saline/nicotine-treated rats developed significantly more periodontal bone loss, and LPS provoked a significantly smaller increase in circulating levels of the cytokines tumour necrosis factor-alpha, transforming growth factor-1beta and interleukin-10. Mecamylamine pretreatment of nicotine-treated rats abrogated the increased periodontal bone loss and the LPS-induced decrease in tumour necrosis factor-alpha, but had no significant effects on the levels of transforming growth factor-1beta and interleukin-10, or the stress hormone corticosterone. CONCLUSION: The results indicate that nicotine enhances the susceptibility to periodontitis via nicotinic acetylcholine receptors, which may act by suppressing protective immune responses through the cholinergic anti-inflammatory pathway.

Early time course of altered leukocyte response to lipopolysaccharide and peptidoglycan in porcine gunshot injury.

BACKGROUND: Penetrating injuries are frequently combined with polybacterial soiling. Clearance of the microorganisms depends on the ability to activate immune responses, but post-traumatic hyporeactivity of immune cells is almost universal. The aim of this study was to map the early time course of this altered leukocyte reactivity, and to compare the reactions to subsequent Gram-positive or Gram-negative challenges. METHODS: Twelve juvenile pigs sustained two standardized rounds, one through the right femur and one through the left upper abdomen. First aid treatment and acute surgery were started immediately. Blood samples were drawn before trauma and after 10, 30, 60, and 90 min, and thereafter stimulated in ex vivo whole blood for 3 h with lipopolysaccharide (LPS, 10 ng/ml), peptidoglycan (PepG, 1 microg/ml), or an equivalent amount of normal saline. The leukocyte response was evaluated by measurement of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-8, and IL-10 in the supernatant. RESULTS: In the post-traumatic in vivo serum, the concentration of TNF-alpha increased steadily (significant after 60 min). A reduced ex vivo reaction to LPS was evident after 10 min, and was statistically significant after 30 min. The lowest levels were reached after 90 min. The ex vivo synthesis of TNF-alpha after stimulation with PepG remained unaltered. A similar development was seen for IL-6. IL-1 beta levels did not change, while IL-8 increased significantly only after 60 and 90 min. CONCLUSIONS: Trauma almost instantaneously reprogrammed circulating leukocytes. As measured with TNF-alpha, a profound hyporeactivity to LPS, but not to PepG, was induced. In addition, no global down-regulation of leukocyte function was found after stimulation with LPS.

In vivo characterization of ischemic small intestine using bioimpedance measurements.

The standard clinical method for the assessment of viability in ischemic small intestine is still visual inspection and palpation. This method is non-specific and unreliable, and requires a high level of clinical experience. Consequently, viable tissue might be removed, or irreversibly damaged tissue might be left in the body, which may both slow down patient recovery. Impedance spectroscopy has been used to measure changes in electrical parameters during ischemia in various tissues. The physical changes in the tissue at the cellular and structural levels after the onset of ischemia lead to time-variant changes in the electrical properties. We aimed to investigate the use of bioimpedance measurement to assess if the tissue is ischemic, and to assess the ischemic time duration. Measurements were performed on pigs (n = 7) using a novel two-electrode setup, with a Solartron 1260/1294 impedance gain-phase analyser. After induction of anaesthesia, an ischemic model with warm, full mesenteric arterial and venous occlusion on 30 cm of the jejunum was implemented. Electrodes were placed on the serosal surface of the ischemic jejunum, applying a constant voltage, and measuring the resulting electrical admittance. As a control, measurements were done on a fully perfused part of the jejunum in the same porcine model. The changes in tan δ (dielectric parameter), measured within a 6 h period of warm, full mesenteric occlusion ischemia in seven pigs, correlates with the onset and duration of ischemia. Tan δ measured in the ischemic part of the jejunum differed significantly from the control tissue, allowing us to determine if the tissue was ischemic or not (P < 0.0001, F = (1,75.13) 188.19). We also found that we could use tan δ to predict ischemic duration. This opens up the possibility of real-time monitoring and assessment of the presence and duration of small intestinal ischemia.

Aminoethyl-isothiourea, a selective inhibitor of inducible nitric oxide synthase activity, improves liver circulation and oxygen metabolism in a porcine model of endotoxemia.

The role of nitric oxide (NO) in hepatic oxygen transport is unclear. We investigated the effects of aminoethyl-isothiourea (AE-ITU), a selective inhibitor of iNOS activity, on liver blood flow and oxygen consumption (VO2H) in the pig. Endotoxin (lipopolysaccharide, LPS) was given intraportally (1.7 microg/kg/h), followed by AE-ITU (10 mg/kg) after 3 h (n = 7), LPS controls (n = 8) received LPS for 6 h. AE-ITU controls (n = 6) received saline/AE-ITU. LPS (treatment group) caused significant reductions at 3 h in cardiac output (CO) from 4.4 +/- .4 to 2.7 +/- .3 L/min, in hepatic artery flow (Q(HA)) from 266 +/- 53 to 127 +/- 19 mL/min, and in portal venous flow (Q(PV)) from 630 +/- 50 to 323 +/- 33 mL/min. Hepatic oxygen delivery (DO2H) was reduced from 93 +/- 11 to 38 +/- 5 mL/min (p < .05), while hepatic oxygen extraction ratio (ERO2H) increased, and VO2H was maintained. Similar changes were observed in LPS controls. AE-ITU caused no changes in saline controls. After injection of AE-ITU during LPS infusion, CO was unchanged, while Q(HA) increased gradually from 127 +/- 20 to 268 +/- 40 mL/min over 3 h (p < .05) and DO2H from 38 +/- 5 to 60 +/- 5 mL/in (p < .05). ERO2H increased from .54 +/- .04 to .69 +/- .03 in 30 min, while VO2H increased from 23 +/- 4 to 35 +/- 3 mL/in in 3 h (p < .05). Thus, AE-ITU restored hepatic arterial blood flow and increased hepatic oxygen consumption in pigs with endotoxemia.

Use of selective and nonselective nitric oxide synthase inhibitors in rat endotoxemia: effects on hepatic morphology and function.

Endotoxin has profound effects on nitric oxide (NO) production, and considerable controversies exist as to whether these alterations are beneficial or deleterious. Increased mortality has been reported from nonselective inhibition of NO synthase. Results from selective inhibition of the inducible isoform (iNOS) appear largely positive. In a model of rat endotoxemia we have compared the early effects on hepatic morphology and function of selective and nonselective NO inhibition. Two hours after endotoxin injection (5 mg/kg intraportally) the rats were treated with either the selective iNOS inhibitor aminoethyl isothiourea (AE-ITU, 10 mg/kg), the nonselective NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg), or normal saline. The animals were observed for another hour. Using an immunohistochemical method, induction of iNOS was demonstrated in various tissues in all slices examined. No unequivocal benefit from NO inhibition was noted. Electron microscopic examination revealed widespread alterations of liver morphology, without obvious differences between the groups. Liver function, as assessed by ketone body ratio, hepatic venous acid base values, and bile production, was generally more adversely affected after NO inhibition. Even with the iNOS selective inhibitor AE-ITU no benefit was noted. We conclude that during the early phases of endotoxemia therapeutic reduction of NO production has no positive effects on liver function or morphology.

The role of Kupffer cell inhibition in porcine endotoxemia.

The selective Kupffer cell inhibitor gadolinium chloride (GdCl3) has been demonstrated to protect animals from lethality in experimental endotoxemia and sepsis in rodent models. This study was designed to investigate the effect of Kupffer cell blockade on the early response to endotoxin in a large animal model. Using a porcine endotoxemia model, animals were randomized to receive either GdCl3 (10 mg/kg or 30 mg/kg; n = 8 in each group) or vehicle saline (n = 8) 24 h before exposure to endotoxin. Pretreatment with GdCl3 resulted in a dose dependent reduction in early hepatic oxygen consumption as well as oxygen extraction ratio in response to continuous infusion of endotoxin. At 5 h there was significant lower serum AST level in animals given 30 mg/kg of GdCl3 as compared to the two other groups. Pretreatment with GdCl3 induced a dose dependent reduction of Kupffer cells in the liver sinusoids. Despite this, all animals deteriorated with continuous infusion of endotoxin as evidenced by the progressive reduction in cardiac output, mean arterial pressure and total liver blood flow. Also, increases in pulmonary arterial pressure, portal venous pressure and systemic, pulmonary and hepatic vascular resistance were seen. This is consistent with activation of other cell populations and defense mechanisms by endotoxin, perpetuating the septic response. However, modulation of reticuloendothelial cell function seems feasible also in larger animals, and our results stimulate to further research on potential immunomodulatory tools in early sepsis.

The nitric oxide donor sodium nitroprusside protects against hepatic microcirculatory dysfunction in early endotoxaemia.

OBJECTIVE: Endotoxin rapidly inhibits the activity of the constitutive endothelial nitric oxide synthase (ecNOS); this precedes the production of NO from inducible NOS (iNOS). This leaves a period in early endotoxaemia with a supposed scarcity of NO. The present study was conducted to examine the effects of external supplementation of NO on liver microcirculation and function. MATERIAL: 13 male Sprague Dawley rats. INTERVENTIONS: The rats underwent laparotomy, and the left liver lobe was exteriorised. All animals were given a bolus dose of endotoxin (LPS) 5 mg/kg intraportally. One group (n = 6) had a continuous infusion of sodium nitroprusside (SNP) 1.4 microg/kg per min started concurrently, the other group (n = 7) was treated with normal saline. The study was terminated after 3 h LPS. MEASUREMENTS AND RESULTS: Intravital microscopy was performed at baseline, at 2 h and 3 h LPS. Hepatic function was assessed by arterial ketone body ratio, acid base values, and bile flow. At baseline 1% of the sinusoids were without perfusion. After 2 h LPS this figure had risen to 9.8+/-1.5% in the SNP group versus 16.9+/-1.4% in the controls (p < 0.05 vs controls). The corresponding values after 3 h LPS were 13.5+/-1.5 versus 19.3+/-1.5% (p < 0.05 vs controls). The leukocyte count in sinusoids and venules had a similar development. Functional parameters were all slightly better preserved in the SNP group, but with no individual significance versus controls. CONCLUSIONS: Infusion of the NO donor SNP in early endotoxaemia attenuates the detrimental effects of LPS on liver microcirculation, most probably by alleviating a relative deficit of NO at the microcirculatory level.

Capacity of glycine to modulate early inflammatory disturbances after serious gunshot injuries in the pig.

OBJECTIVE: Perturbation of immune homeostasis is an important determinant for organ dysfunction following multiple injuries. The aim of this study was to investigate the ability of glycine to influence the immediate post-traumatic inflammatory environment and altered reactivity of circulating leucocytes. MATERIAL AND METHODS: Twenty pigs were subjected to two standardized gunshots to the abdomen and thigh. Treatment was started immediately. The animals were randomized to receive either glycine 180 mg/kg i.v. over 30 min (n=10) or normal saline (n=10). Blood samples were drawn at baseline and 75 min after injury. In a follow-up study 12 pigs were exposed to an identical trauma. Blood was drawn at the same time-points and stimulated with lipopolysaccharide (LPS) or LPS plus glycine for 2 h in an ex vivo whole blood model. RESULTS: Selected physiologic variables and organ injury did not differ between groups 75 min after trauma. Reactive oxygen species decreased to 82.7+/-5.5 % of baseline (p<0.05) in the glycine group (unaltered in the controls). Liver glutathione concentrations decreased in parallel in both groups. In vivo production of TNF-alpha and IL-1-beta increased to the same extent regardless of treatment. Trauma induced a strong LPS tolerance. In whole blood challenged with LPS, glycine inhibited cytokine synthesis, but only in samples drawn at baseline. CONCLUSIONS: Post-traumatic infusion of glycine only modestly influenced the early post-traumatic inflammatory environment. Our ex vivo results confirm previous reports on the anti-inflammatory potential of glycine, but restricted to pre-trauma conditions.

Response of circulating immune cells to major gunshot injury, haemorrhage, and acute surgery.

PURPOSE: The purpose of this study was to use an established porcine model to investigate the effects on immune function of severe gunshot injury. METHODS: Twelve pigs sustained two standardised rounds, one through right femur and one through left upper abdomen. First aid treatment and acute surgery was started immediately. Blood samples were drawn before shooting and after 75 min. Circulating neutrophils were isolated and reactive oxygen species (ROS) measured. Serum levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, and IL-10 were determined at 0, 75 min, as well as 2h after incubation with 1 microg/ml endotoxin in an ex vivo whole blood model. RESULTS: TNF-alpha, IL-1beta, and IL-6 significantly increased at 75 min. ROS in circulating granulocytes tended to increase (NS). Incubation with endotoxin led to a more than 100-fold increase of TNF-alpha pre-trauma, compared to a three-fold increase post-trauma (p<0.0001 between groups). A similar pattern was obtained for IL-1beta, and IL-6. IL-10 was below detection in all samples. The granulocytes maintained their ability to react to the protein kinase C activator phorbol myristate acetate (PMA) after trauma. CONCLUSION: Severe gunshot injury and peritraumatic stress rapidly activate circulating immune cells, but reduce their capacity to react to a subsequent challenge to endotoxin.

[Steroid treatment of shock lung--tune for re-evaluation?]. / Steroidbehandling av sjokklunge--tid for revurdering?

BACKGROUND: The acute respiratory distress syndrome (ARDS) is one consequence of the body's systemic inflammatory response to a variety of powerful external stimuli. Glucocorticosteroids are highly effective anti-inflammatory drugs. During the last few years, the molecular mechanisms for their mode of action have been revealed; this has prompted a new wave of interest in corticosteroid treatment of systemic inflammatory states. Several clinical studies have been launched; the results have so far been promising. MATERIAL AND METHODS: We briefly discuss how new knowledge in this field may influence the use of corticosteroids in the treatment of ARDS. The presentation is illustrated by a case study. RESULTS: The patient was a 15-year-old boy with life-threatening and therapy-resistant ARDS. He was treated in a respirator in an intensive care unit (ICU). Two weeks after admission to the ICU, his situation was desperate. High-dose corticosteroids were instituted, and during a five days' treatment his condition improved dramatically. After discontinuation of glucocorticoids he made further progress and was discharged from the ICU after another eleven days. INTERPRETATION: In this particular patient, administration of glucocorticoids had a striking effect. The influence of glucocorticoids on the activation of the transcription factor NF-kappa B and a resulting reduced synthesis of a number of key inflammatory molecules may be one explanation for the positive course.

Modest protection of early hydrocortisone treatment in a rat model of volume-controlled haemorrhage.

BACKGROUND: Major insults may trigger generalized inflammatory responses that contribute to progressive multiple organ dysfunction. The present study was performed to test the potential of early hydrocortisone treatment to influence these responses as well as organ function following an episode of rapid and profound blood loss. METHODS: In isoflurane anaesthesia, 35 spontaneously breathing male Sprague-Dawley rats were bled 2.5 ml 100 g-1 body weight over 10 min. Immediately following withdrawal of blood, one group (n = 17) was given 2 mg of hydrocortisone, and the other (n = 18) had the same amount of normal saline. Seventy-five minutes after initiation of bleeding, two-thirds of the blood was retransfused, together with a new injection of hydrocortisone or saline. Thereafter the rats were observed for 2 h. Key mediators of systemic inflammation and plasma markers of organ function and integrity were measured. Internal organs were weighed and scored for visible pathology. Leukocyte infiltration of the liver was counted in a light microscope. RESULTS: Hydrocortisone reduced the plasma levels of IL-6 (P < 0.05); non-significant reductions of TNF-alpha (P = 0.12) and IL-10 (P = 0.44) were noted. The synthesis of reactive oxygen species in peritoneal cells was unaffected. Relative organ weights and organ injury scores tended to be reduced, but only wet organ weight for the lungs reached statistical significance. Leukocyte infiltration of the liver was equal in both groups. Plasma levels of ALT, AST, alpha-GST and creatinine did not differ significantly between groups. Two of the hydrocortisone treated rats died compared with four controls. CONCLUSION: Early treatment with hydrocortisone had a limited organ protective effect in this model of controlled haemorrhagic shock. Although a general tendency for better outcome in the hydrocortisone group was noted, clear-cut and significant advantages of the treatment were not obtained.

Peroperative hypothermia.

Heat loss during anesthesia and operation and subsequent hypothermia will increase the postoperative oxygen demand and may endanger patients with restricted cardiopulmonary reserves. Forty patients scheduled for intra-abdominal aortic surgery and 40 patients scheduled for peripheral vascular surgery on the lower limbs were investigated using a warming blanket, humidified heated inspired anesthetic gases at 37-40 degrees C, or both these methods together. A fourth group of patients received no active warming. A warming blanket used alone gave no protection against hypothermia when compared with no active warming. In the abdominal surgical group, there was a steady fall in temperature throughout the operation if no warming method was employed. In this group the use of humidified, heated inspired gases was significantly better than no treatment after 2 h of anesthesia (P less than 0.05). The combination of humidified and heated inspired gases and a warming blanket gave significantly better heat preservation after 40 min (P less than 0.05). Patients undergoing peripheral vascular surgery had similar but smaller drops in temperature with the different types of warming procedures employed. The differences in temperature between the intra-abdominal and extra-abdominal operations were statistically significant after 3 h (P less than 0.05).

Modulators of nitric oxide in porcine endotoxemia: effects on hepatic oxygen delivery and consumption.

In a porcine model of endotoxemia we have studied the effects of nitric oxide (NO) on hepatic oxygen delivery and consumption. After 3 h of endotoxemia, NO biosynthesis was modulated by a bolus dose of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME). Fifteen minutes thereafter a continuous infusion of the NO donor sodium nitroprusside (SNP) was started. Endotoxin significantly reduced hepatic oxygen delivery from 3.4 +/- 0.6 to 2.2 +/- 0.3 ml/kg/min at 3 h. Due to an increased extraction ratio (ER), oxygen consumption was nearly unaffected. L-NAME further diminished oxygen delivery to 1.0 +/- 0.2 ml/kg/min within 15 min (p < 0.05), but despite an increase in ER from 47 to 68% (p < 0.05), oxygen consumption tended to decrease (from 1.0 to 0.7 ml/ kg/min, nonsignificant). A similar tendency was observed in a control group of 9 pigs which was treated in the same way as the study group, except for the SNP infusion. SNP induced an almost selective increase in hepatic arterial flow, with a corresponding increase in oxygen delivery to 1.8 +/- 0.3 ml/kg/min (p < 0.05). At the same time ER was reduced from 68 to 42% (p < 0.05). Oxygen consumption remained unaltered. The control group exhibited no change in either oxygen delivery or consumption. The study shows that nonselective inhibition of NO synthesis is detrimental to hepatic perfusion and oxygen transport. The NO donor SNP increased oxygen delivery via a selective increase in hepatic arterial flow, but failed to influence oxygen consumption. This was probably mainly due to a massive shutdown of sinusoids, which did not reopen when flow was increased. A functioning microcirculation thus seems to be a prerequisite for the stimulation of organ blood flow to be effective.

Effects of the nitric oxide synthase inhibitors N(G)-nitro-L-arginine methyl ester and aminoethyl-isothiourea on the liver microcirculation in rat endotoxemia.

BACKGROUND/METHODS: The question whether nitric oxide protects or impairs organ perfusion during early endotoxemia has not been completely answered. To evaluate the regulative function of nitric oxide on organ microvascular perfusion and leukocyte accumulation during endotoxemia, we studied the influence of a non-selective nitric oxide inhibitor and a preferential inducible nitric oxide synthase inhibitor (respectively, N(G)-nitro-L-arginine methyl ester and aminoethyl-isothiourea) on liver microcirculation (intravital fluorescence microscopy) in a rat model. RESULTS: Two hours after intraportal injection of lipopolysaccharide (5 mg/kg in 10 min) the rats were randomly treated and received a bolus dose of N(G)-nitro-L-arginine methyl ester (10 mg/kg, n = 7), aminoethyl-isothiourea (10 mg/kg, n = 6) or normal saline, (n = 7). After 1 h, N(G)-nitro-L-arginine methyl ester blockade yielded a higher rate of non-perfused sinusoids than normal saline (27 +/- 2% vs 19 +/- 5%, p < 0.05). LPS-induced leukocyte stagnation in sinusoids was further increased (p < 0.05) in all groups after 1 h treatment, but N(G)-nitro-L-arginine methyl ester clearly accentuated leukocyte accumulation in sinusoids as compared to normal saline (69 +/- 19% vs 16 +/- 4%, p < 0.05). Both modalities of nitric oxide blockade elicited a significant enhancement in the number of leukocytes adherent to the postsinusoidal venules in contrast to normal saline (N(G)-nitro-L-arginine methyl ester 48 +/- 17%, aminoethyl-isothiourea 33 +/- 9% vs normal saline 1 +/- 5%, p < 0.05). CONCLUSIONS: We conclude that complete nitric oxide blockade aggravates lipopolysaccharide-induced hepatic microvascular perfusion failure and enhances leukocyte accumulation, in both sinusoids and post-sinusoidal venules. The preferential inducible nitric oxide synthase inhibitor aminoethyl-isothiourea has a moderate negative effect, favoring leukocyte adhesion in postsinusoidal venules, and its usefulness demands further research, especially concerning its late effects.

Selective inhibition of inducible nitric oxide synthase maintains haemodynamic stability without untoward consequences for hepatic function or morphology.

OBJECTIVE: To examine the effects of the inducible nitric oxide synthase inhibitor aminoethyl-isothiourea (AE-ITU) on haemodynamic measurements, and correlate these with hepatic morphology and function in a porcine model of endotoxaemia. DESIGN: Experimental study. ANIMALS: 15 juvenile pigs. INTERVENTIONS: Flow probes were placed around the hepatic artery and portal vein. Catheters were introduced into the portal and hepatic veins, pulmonary artery, and aorta. Infusion of AE-ITU was started one hour before that of endotoxin (study group n = 6); thereafter both substances were infused simultaneously until the end of the study (6 hours). The controls (n = 9) had endotoxin alone. MAIN OUTCOME MEASURES: Hepatic morphology assessed by light and electron microscopy; and hepatic integrity and function by transaminase activities and oxygen consumption. Systemic, pulmonary, and hepatic blood flow and pressure. RESULTS: AE-ITU maintained systemic blood pressure (p < 0.05 compared with controls) without causing pulmonary hypertension. Neither hepatic morphology nor function were adversely influenced. CONCLUSION: In endotoxaemia AE-ITU has a favourable haemodynamic profile which is achieved without impairment of hepatic function or morphology.

Moderate hypothermia blunts the inflammatory response and reduces organ injury after acute haemorrhage.

BACKGROUND: Reduced body temperature is a common companion to trauma/haemorrhage. Several clinical studies have identified hypothermia as an independent risk variable predisposing to increased morbidity and mortality. At the same time it is known that most enzymatic reactions are downregulated at temperatures below 37 degrees C. Theoretically this should restrain the inflammatory response and protect the host from remote organ injury. The study was performed to test this hypothesis. METHODS: Twenty-six male Sprague Dawley rats were used for the experiments. Volume controlled haemorrhagic shock was induced by withdrawal of 2.5 ml blood/100 g body weight over 10 min. Half of the animals (n=13) were then cooled to 32.5-33 degrees C, the other half (n=13) were kept normothermic (37.5+/-0.5 degrees C). Seventy-five minutes after initiation of bleeding, two-thirds of the blood was retransfused. Thereafter the rats were observed for 2 h. Key substances of systemic inflammation were determined (plasma values of TNF-alpha, IL-6, IL-10, and corticosterone; reactive oxygen species in peritoneal phagocytes), plasma markers of organ function and integrity (AST, ALT, alphaGST, creatinine, urea), and survival. RESULTS: Hypothermia reduced the release of IL-6 (P<0.01). The reductions of plasma levels of TNFalpha (P=0.07) and IL-10 (P=0.09) were less clear-cut. The release of reactive oxygen species diminished (P<0.01). Organ injury was ameliorated, as reflected by decreased levels of AST (P<0.01), alphaGST (P<0.01), and creatinine (P<0.01). Both groups experienced an almost identical increase of plasma corticosterone. None of the hypothermic rats died, compared to two normothermic. CONCLUSION: Moderate hypothermia had an organ protective effect in this model of controlled haemorrhagic shock. This coincided with a significant reduction of the proximal cytokine IL-6 and reactive oxygen species, which conceivably influenced the outcome.