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Query: UMLS:C0243026 (sepsis)
 52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO) is a multifunctional messenger in many vertebrates. In the liver, NO was found to play an important but controversial role in injury produced by toxins or sepsis. The purpose of the present investigation was to further characterize the role of NO in hepatocyte oxidative injury. A cellular system formed of immobilized and perfused rat hepatocytes was used to test the ability of the latter to produce endogenous NO after lipopolysaccharide administration in vivo (LPS, 20 mg/kg i.p.) and how hepatocyte functionality competence is modified according to NO level. This cellular system also was used to delineate a relationship between exogenously delivered NO to the perfusion medium as produced by the NO donor, sodium nitroprusside (2.0 and 0.2 mM), and any alteration in the degree of injury as evoked by anoxia/reoxygenation or cumene hydroperoxide (1.0 mM and 0.2 mM). Rat hepatocytes were immobilized in low-gelling agarose and perfused with Williams E medium. Endogenous or exogenous NO was evaluated by measuring the end products of NO (NO2- + NO3-) in the perfusion medium. Functional integrity of hepatocytes was evaluated from lactate dehydrogenase (LD) leakage, urea synthesis in the perfusion medium and lipid peroxides (LP) formation. Normal, anoxia/reoxygenation or cumene hydroperoxide injured hepatocytes did not exhibit measurable NO while LPS-treated hepatocytes produced NO. Apparently, within the present experimental conditions, it seems that there was an inverse relation between the rate of NO produced after LPS administration and the rate of lipid peroxides formed in the hepatocytes. Low concentration of sodium nitroprusside (as NO donor) significantly decreased LD leakage, increased the rate of urea synthesis and increased trypan blue exclusion by hepatocytes in anoxia/reoxygenation or cumene hydroperoxide injured (0.2 mM) cells. Lipid peroxides were decreased by NO in cumene hydroperoxide injured hepatocytes. The present data suggest that NO endogenously produced, or exogenously delivered, has an ameliorative role in mild oxidative liver injury models, but not in severe cases and that inside hepatocytes, there is a very delicate balance between the rate of NO production and its consumption. The disturbance in this balance may be responsible for injury due to the formation of more toxic oxygen species.
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PMID:Possible dual role of nitric oxide in oxidative stress injury: a study in perfused hepatocytes. 963 60

There is increasing evidence that nitric oxide (NO) is an important factor in the pathogenesis of septic shock. It is known that polymorphonuclear neutrophils (PMNs) are activated during sepsis or after surgical stress, and they then release various toxic mediators including free radicals. It has not been clear whether NO synthesis can be induced in circulating PMNs. Blood samples were obtained from 11 patients with sepsis, 23 patients with systemic inflammatory response syndrome (SIRS), and 16 patients without SIRS (nonSIRS) who underwent operation. We examined mRNA expression of inducible NO synthase (iNOS) in circulating PMNs from those patients pre- and postoperatively using the reverse transcriptase polymerase chain reaction (RT-PCR) method and measured their serum nitrate (NO2-) + nitrate (NO3-) concentration, peripheral blood white cell (WBC) count, and serum C-reactive protein (CRP) level. The frequency of iNOS expression in PMNs increased in sepsis (100%) and SIRS (70%) patients compared to that in nonSIRS patients (18%) (p < 0.001). The peripheral WBC count and CRP level were significantly higher in iNOS-positive patients than in iNOS-negative patients (p < 0.05 and p < 0.01, respectively). Postoperatively, the serum NO2- + NO3- concentration increased in 87% of septic patients and in 56% of patients with SIRS (p < 0.05 for both). Our study indicated that iNOS mRNA expression is induced in human circulating PMNs of patients with postoperative sepsis and SIRS and may be involved in the pathogenesis of the sepsis syndrome.
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PMID:Expression of inducible nitric oxide synthase in circulating neutrophils of the systemic inflammatory response syndrome and septic patients. 967 45

Nitric oxide (NO) is an important mediator in numerous physiological and pathophysiological events. After thermal injury an increase in plasma and urinary levels has been observed. The real importance of this fact is unknown. The stable NO derivatives (NO2-/NO3-) plasma concentrations were determined in 27 burned patients admitted to the Burn Unit at Santa Maria Hospital in Lisbon at first, third, fifth, seventh, ninth and 15th days and the values were compared with healthy controls (n=9). A significant increase (P<0.05) in burn patient determinations upon admission was found. The patients with inhalation injury revealed greater values compared to the other patients with statistical significance at 5th day (P<0.05). The patients who died showed a NO increase (0.397+/-0.138 vs. 0.267+/-0.017, P> 0.1, day 1) with significance at day 5 (0.615+/-0.223 vs. 0.154+/-0.048, P<0.05). The determinations in patients with sepsis were higher than in the other patients (P<0.01) at day 3. No relation with total burned surface area (TBSA) was found. For the first time, considering burned patients, a significant increase of NO was found in patients who died, in patients with inhalation injury and in patients in sepsis. The possible role of NO in burn injury is discussed. The authors suggest the possible role of NO determination as an indicator of sepsis. The role of NO synthesis inhibitors is discussed. Further studies are needed to clarify these questions.
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PMID:Nitric oxide and human thermal injury short term outcome. 967 22

Vascular endothelium releases nitric oxide (NO), an important vasodilator that is continuously synthesised by the constitutive enzyme, endothelial nitric oxide synthase (NOS). This maintains a constant vasodilator tone which is diminished in adult hypertension, due to reduced endothelium-dependent vascular relaxation, which is NO dependent. In childhood, however, hypertension is often secondary, and normalisation of blood pressure by removal of cause (e.g. renal artery stenosis, catecholamine-producing tumour) suggests reversibility of endothelial dysfunction, if it is present. Raised plasma levels of endogenous inhibitors have been found, especially in children with secondary hypertension due to renal parenchymal and renovascular disease, and may contribute to hypertension by more than just inhibition of vascular NO release; e.g. by reduction of glomerular filtration rate and promotion of salt and water retention. These inhibitors also modulate renin release, which may be of relevance in cardiovascular physiology, and may also interfere with the anti-platelet properties of NO, increasing the likelihood of vascular thrombotic events. NO inhibitors also promote endothelial activation, with increased expression of adhesion molecules that may form seedlings of atherosclerosis. In chronic renal impairment, accumulation of NO inhibitors may contribute to hypertension. Efficient long-session dialysis helps better interdialysis control of blood pressure in these subjects, independent of salt and water removal, suggesting that removal of such vasoactive agents may be important for efficient blood pressure control. There are a few studies assessing NO generation in hypertensive children via plasma nitrite and nitrate, the NO end products, which suggest normal or increased production as opposed to a reduction, perhaps as a compensatory phenomenon. In the treatment of hypertension, nitroprusside and nitrates exert their actions via NO donation. Excessive production of NO (usually via inducible NOS) or excessive administration (nitrovasodilators) can be cytotoxic and may cause hypotension and shock, as in severe sepsis. NOS inhibitors and NO therefore appear to play a crucial role in aetiology, complications and therapy of childhood hypertension.
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PMID:Vascular endothelium and nitric oxide in childhood hypertension. 981 94

Excess production of nitric oxide contributes to the refractory hypotension associated with sepsis and is dependent upon precursor availability, L-arginine. Endothelial uptake of L-arginine by the y+ transporter can be inhibited by another cationic amino acid, L-lysine. This study was undertaken to determine the effects of L-lysine in an anaesthetized ovine model of endotoxaemia in which nitric oxide production is known to be limited by L-arginine availability. The haemodynamic effects of i.v. L-lysine (500 mg kg-1) were compared with those of a known inhibitor of nitric oxide synthase, NG-nitro-L-arginine-methyl ester, L-NAME (25 mg kg-1) and with control animals (n = 6 per group). Serum nitrates, the stable end metabolite of nitric oxide production, were also measured. L-NAME administration caused a significant increase in systemic and pulmonary vascular resistance (P < 0.0001), mean arterial pressure (P < 0.0001) and a reduction in serum nitrate concentrations (P < 0.0001). The administration of L-lysine had no effect on systemic or pulmonary vascular resistance, mean arterial pressure or serum nitrate concentrations. We conclude that the administration of L-lysine does not inhibit nitric oxide production in this model.
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PMID:Effect of L-lysine on nitric oxide production in ovine endotoxaemia. 981 21

A new silver-coating technology was developed to prevent wound adhesion, limit nosocomial infection, control bacterial growth, and facilitate burn wound care through a silver-coated dressing material. For the purposes of this article, Acticoat (Westaim Biomedical Inc, Fort Saskatchawan, Alberta, Canada) silver-coated dressing was used. After in vitro and in vivo studies, a randomized, prospective clinical study was performed to assess the efficacy and ease of use of Acticoat dressing as compared with the efficacy and ease of our institution's standard burn wound care. Thirty burn patients with symmetric wounds were randomized to be treated with either 0.5% silver nitrate solution or Acticoat silver-coated dressing. The dressing was evaluated on the basis of overall patient comfort, ease of use for the wound care provider, and level of antimicrobial effectiveness. Wound pain was rated by the patient using a visual analog scale during dressing removal, application, and 2 hours after application. Ease of use was rated by the nurse providing wound care. Antimicrobial effectiveness was evaluated by quantitative burn wound biopsies performed before and at the end of treatment. Patients found dressing removal less painful with Acticoat than with silver nitrate, but they found the pain to be comparable during application and 2 hours after application. According to the nurses, there was no statistically significant difference in the ease of use. The frequency of burn wound sepsis (> 10(5) organisms per gram of tissue) was less in Acticoat-treated wounds than in those treated with silver nitrate (5 vs 16). Secondary bacteremias arising from infected burn wounds were also less frequent with Acticoat than with silver nitrate-treated wounds (1 vs 5). Acticoat dressing offers a new form of dressing for the burn wound, but it requires further investigation with greater numbers of patients in a larger number of centers and in different phases of burn wound care.
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PMID:A matched-pair, randomized study evaluating the efficacy and safety of Acticoat silver-coated dressing for the treatment of burn wounds. 984 45

Levels of procalcitonin (ProCT) have been found to be elevated in individuals with severe bacterial infections such as sepsis and peritonitis, and this correlates well with the severity of the disease. Recently, increased levels have been described in melioidosis and Plasmodium falciparum malaria. In this study ProCT levels were measured in 27 Thai patients with complicated malaria before and during/after treatment with artesunate and mefloquine. Initial parasite counts averaged 290,680/microl (range = 533-1,147,040). On admission, ProCT levels were elevated in all but one patient (median = 40 ng/ml, range = 0.04-662, normal values < 0.5 ng/ml). With treatment, levels decreased to 1.3 ng/ml (range = 0.01-6.5). Nitrite/nitrate levels in patients were higher than in controls throughout the study. The ProCT levels correlated with initial parasite density (P < 0.05), which is a marker of disease severity, and with nitrite/nitrate levels (P < 0.05). Based on the changes of ProCT levels over the course of the disease a possible role in the acute-phase reaction seems likely.
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PMID:Serum procalcitonin levels in severe Plasmodium falciparum malaria. 988 89

Systemic hypotension during sepsis is thought to be due to nitric oxide (NO) overproduction, but it may also be due to acidosis. We evaluated in healthy rats the consequences of acid infusion on NO and blood pressure. Sprague-Dawley rats were anesthetized, and ventilated with room air. The animals were randomized into four groups. Group 1 (C, n = 10) received only normal saline at rates comparable to the other groups. Group 2 (A1, n = 10) received hydrochloric acid at 0.162 mmol in the first 15 to 30 min, followed by a continuous infusion of 0.058 mmol/h for 5 h. Group 3 (AG+A1, n = 6) was pretreated with aminoguanidine (AG, 50 mg/kg), and HCl was infused as above. Group 4 (A2, n = 7) received HCl at twice the rate used in A1. Nitric oxide concentration in the exhaled gas (ENO), blood gases, and mean arterial pressure were measured every 30 min. Acid infusion in A1 caused the pH to fall gradually from 7.43 +/- 0. 01 to 7.13 +/- 0.05. This moderate decrease in pH was associated with a marked increase in ENO (1.6 +/- 0.3 to 114.2 +/- 22.3 ppb), an increase in plasma nitrite/nitrate (17.3 +/- 3.7 to 35.2 +/- 4.3 microM), and a significant decrease in blood pressure (110.5 +/- 6.3 to 63.3 +/- 15.0 mm Hg). Furthermore, acidosis caused lung inflammation, as suggested by the increase in lung myeloperoxidase activity (282.2 +/- 24.7 to 679.3 +/- 57.3 U/min/g) and lung injury score (1.7 +/- 0.2 to 3.5 +/- 0.6). Acidosis after AG pretreatment was associated with a similar change in pH, but the increase in ENO, nitrite/nitrate, and systemic hypotension were prevented. Furthermore, lung injury was attenuated by AG, as suggested by a lower myeloperoxidase activity, though lung injury score was not altered. In this model, moderate acidosis causes increases in NO, hypotension, and lung inflammation. Lung inflammation and injury are due in part to acidosis and NO production. This is the first report to show a direct effect of chronic acidosis on NO production and lung injury. These results have profound implications on the role of acidosis on NO production and lung injury during sepsis.
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PMID:Acidosis stimulates nitric oxide production and lung damage in rats. 992 49

Nitric [correction of Nitrous] oxide is most likely a queer "end mediator" giving rise to vasoplegia in septic shock patients. The study is aimed at comparative assessment of kinetic changes in the synthesis of nitric [correction of nitrous] oxide in experimentally induced sepsis model with the corresponding hemodynamic parameters. The laboratory animals--pigs--are divided up in two groups, and exposed to general narcosis induction, orotracheal intubation and mechanical ventilation under controlled regimen. The hemodynamic parameters studied include: MAP, CO and SVR. Additional endotoxin (1 mg/50 ml) in the form of infusion is given to the animals in the sepsis group. Nitrate production mirrors NO synthesis, insofar as there are no other relevant mechanisms of nitrate synthesis. The kinetic parameters of nitrate production are estimated using stable nitrate isotopes--N15. The theory of compartment models and appropriate computerized simulation are used to calculate the respective constants. In the endotoxin treated group (n = 5) a significantly higher level of synthesis of induced NO production is documented--26 +/- 9 mumol/h, as compared to production in the control group--6 +/- 7 mumol/h, as well as a significant increase in cardiac output and systemic vascular resistance reduction. The good correlation between enhanced NO production and hemodynamic response (increase in cardiac output and decrease in systemic vascular resistance) corroborates the validity of the method.
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PMID:[Hemodynamic changes and nitric oxide production in an experimental model of sepsis]. 997 38

Enhanced intestinal nitric oxide production observed during sepsis is thought to play a central role in lipopolysaccharide-induced intestinal damage. In contrast intestinal polyamines, both from endogenous and exogenous origin, are essential for the maintenance of mucosal integrity. Polyamines have been shown to inhibit lipopolysaccharide-induced nitric oxide release in vitro and have been claimed to exert additional antiinflammatory actions. In this study, the effect of the polyamine spermine on the release of the proinflammatory mediators nitric oxide and tumor necrosis factor-alpha by a murine macrophage cell line was investigated. Furthermore, we investigated whether oral spermine administration inhibits lipopolysaccharide-induced intestinal inducible nitric oxide synthase and nitrotyrosine expression and modulates the release of inflammatory mediators. Our results show that although spermine inhibited lipopolysaccharide-induced nitric oxide release in a murine macrophage cell line, no effect on tumor necrosis factor-alpha release was observed. In addition, oral spermine administration inhibited intestinal inducible nitric oxide synthase and nitrotyrosine expression suggesting a protective effect of spermine on lipopolysaccharide-induced intestinal damage. In parallel a decrease in serum levels of the proinflammatory mediators nitrate, nitrite, and interferon-gamma and an increase in the antiinflammatory cytokine interleukin-10 was observed, although tumor necrosis factor-alpha levels were unaffected. These results indicate that spermine inhibits lipopolysaccharide-induced nitric oxide release in vitro as well as in vivo. Further, intraluminally derived polyamines modulate the systemic immune response. It is concluded that oral spermine administration might have therapeutic perspectives for several disorders characterized by systemic inflammation and intestinal damage.
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PMID:Oral spermine administration inhibits nitric oxide-mediated intestinal damage and levels of systemic inflammatory mediators in a mouse endotoxin model. 1003 Jul 98


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