Small bowel ischaemia-reperfusion increases plasma concentrations of oxidised proteins in rats.

OBJECTIVES: To find out whether plasma concentrations of protein carbonyl (a specific marker of oxidative damage of proteins) are increased during intestinal ischaemia-reperfusion and whether they are correlated with von Willebrand's factor (vWF, a marker of endothelial injury) or myeloperoxidase (a marker of neutrophil activation). DESIGN: Randomised experimental study. SETTING: University department of surgery, New Zealand. ANIMALS: Thirty anaesthetised adult Wistar rats. INTERVENTIONS: The sham operated group (n = 10) had laparotomy and isolation of the superior mesenteric artery without clamping. The ischaemia-reperfusion group (IR, n = 10) had the superior mesenteric artery clamped for 1 hour and reperfusion for 15 minutes. The control group (n = 10) had direct puncture of the heart to sample blood. MAIN OUTCOME MEASURES: Plasma concentrations of protein carbonyl, vWF, and myeloperoxidase. RESULTS: Plasma protein carbonyl concentrations were significantly higher in the IR group than in the sham group (p < 0.02, Mann-Whitney test, median (range) 0.187 (0.141-0.242) compared with 0.144 (0.121-0.185) nmol/mg) and in the control group (p < 0.01, Mann-Whitney test, median (range) 0.187 (0.141-0.242) compared with 0.136 (0.108-0.175) nmol/mg). There was a significant correlation between protein carbonyl and vWF concentrations (r = 0.54, F = 10.9, p < 0.003, linear regression) but not with those of myeloperoxidase. CONCLUSION: Intestinal ischaemia-reperfusion caused an increase in the plasma protein carbonyl concentration, which is possibly produced by endothelial cells.     

Oxidative stress is increased in critically ill patients with acute renal failure

Patients with acute renal failure (ARF) experience a high mortality rate. Dysregulated inflammation and altered metabolism may increase oxidative stress in ARF patients. Thirty-eight patients who met the Program to Improve Care in Acute Renal Disease (PICARD) Study inclusion criteria underwent plasma protein oxidation and plasma cytokine measurements. For comparison, similar measurements were also performed in 21 critically ill patients without ARF, 28 patients with ESRD, and 49 healthy subjects. Plasma protein thiol oxidation was measured by spectrophotometry. Plasma protein carbonyl content and cytokine concentrations were measured by ELISA. Plasma protein thiol oxidation and carbonyl content were markedly different in ARF patients compared with healthy subjects, ESRD patients, and critically ill patients (P < 0.001 in all cases). There were significant but less marked differences in plasma protein oxidation between ESRD patients and critically ill patients compared with healthy subjects. Plasma protein thiol oxidation in ARF patients improved with dialysis (P < 0.001); however, there was significant plasma oxidant reaccumulation during the interdialytic period (P < 0.001) not due to rebound equilibration of compartmentalized solutes. Plasma proinflammatory cytokine levels were significantly higher (P < 0.05) in ARF patients and critically ill patients than in healthy subjects. Plasma protein oxidation is markedly increased in ARF patients compared with healthy subjects, ESRD patients, and critically ill patients. Increased oxidative stress may be an important target for nutritional and pharmacologic therapy in ARF patients.     

Albumin is the major plasma protein target of oxidant stress in uremia.

BACKGROUND: Patients with uremia are exposed to increased oxidative stress. Examination of the oxidation of individual plasma proteins may be useful in establishing specific pathways of oxidative stress in vivo and in determining functional consequences of oxidant stress exposure. We therefore examined oxidative modification of plasma proteins by carbonyl formation using Western blot immunoassay and enzyme-linked immunosorbent assay (ELISA) techniques in patients with chronic renal failure (CRF) and on chronic hemodialysis therapy (HD). METHODS: Plasma was obtained from 25 HD, 20 CRF, and 20 healthy volunteers, derivatized with 2,4 dinitrophenylhydrazine (DNP) and electrophoresed on duplicate 4 to 12% gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels, transferred to nitrocellulose, and stained for DNP for carbonyls and amido black for protein content. Data are recorded as DNP area/protein area and are reported in densitometry units. Total plasma carbonyls were determined by ELISA. RESULTS: Plasma albumin is substantially more oxidized in HD than in healthy volunteers (1.22 +/- 0.14 densitometry units vs. 0.60 +/- 0.08, P = 0.002). There were no significant differences in oxidation of plasma transferrin, immunoglobulin, and fibrinogen in HD versus healthy volunteers. In CRF patients, plasma albumin is more oxidized compared with normal volunteers (1.36 +/- 0.20 densitometry units vs. 0.94 + 0.08, P = 0.09). There were no differences in oxidation of plasma transferrin, fibrinogen, and immunoglobulin in CRF patients versus healthy volunteers. An increased plasma protein carbonyl concentration in CRF patients compared with healthy volunteers was confirmed by ELISA (0.31 +/- 0.07 vs. 0.04 +/- 0.01 nmol/mg protein (P = 0.001). CONCLUSION: Albumin is the major plasma protein target of oxidant stress in CRF and HD patients.     

Plasma protein thiol oxidation and carbonyl formation in chronic renal failure

BACKGROUND: Myeloperoxidase-catalyzed oxidative pathways have recently been identified as an important cause of oxidant stress in uremia and hemodialysis (HD), and can lead to plasma protein oxidation. We have examined patterns of plasma protein oxidation in vitro in response to hydrogen peroxide (H2O2) and hypochlorous acid (HOCl). We measured thiol oxidation, amine oxidation, and carbonyl concentrations in patients on chronic maintenance HD compared with patients with chronic renal failure (CRF) and normal volunteers. We have also examined the effect of the dialysis procedure on plasma protein oxidation using biocompatible and bioincompatible membranes. METHODS: Plasma proteins were assayed for the level of free thiol groups using spectrophotometry, protein-associated carbonyl groups by enzyme-linked immunosorbent assay, and oxidation of free amine groups using a fluorescent spectrophotometer. RESULTS: In vitro experiments demonstrate HOCl oxidation of thiol groups and increased carbonyl formation. In vivo, there are significant differences in plasma-free thiol groups between normal volunteers (279 +/- 12 micromol/L), CRF patients (202 +/- 20 micromol/L, P = 0.005) and HD patients (178 +/- 18 micromol/L, P = 0.0001). There are also significant differences in plasma protein carbonyl groups between normal volunteers (0.76 +/- 0.51 micromol/L), CRF patients (13.73 +/- 4.45 micromol/L, P = 0.015), and HD patients (16.95 +/- 2.62 micromol/L, P = 0.0001). There are no significant differences in amine group oxidation. HD with both biocompatible and bioincompatible membranes restored plasma protein thiol groups to normal levels, while minimally affecting plasma protein carbonyl expression. CONCLUSIONS: First, both CRF and HD patients have increased plasma protein oxidation manifested by oxidation of thiol groups and formation of carbonyl groups. Second, HD with biocompatible and bioincompatible membranes restored plasma protein thiol groups to normal levels. Third, these experiments suggest that there is a dialyzable low molecular weight toxin found in uremia that is responsible for plasma protein oxidation.     

The plasma leptin concentration is closely associated with the body fat mass in nondiabetic uremic patients.

Plasma leptin is associated with the body mass index and, more precisely, with the body fat mass. Plasma leptin has been found to be elevated in uremic patients. This study aimed at investigating the plasma leptin concentration and associations between plasma leptin, body fat mass, and glomerular filtration rate in nondiabetic predialysis uremic patients and in nondiabetic patients on chronic hemodialysis. Plasma leptin, body fat mass, and creatinine clearance were measured in 22 predialysis uremic patients, 18 hemodialysis patients, and 24 healthy control subjects. The logarithmically transformed plasma leptin concentration was closely associated with the body fat mass in all groups (r = 0.93, r = 0.83, and r = 0.72, respectively; p < 0.000001, < 0.000002 and p < 0.001, respectively). In predialysis uremic patients the plasma leptin concentration was slightly elevated as compared with controls 10.4 (3.1-59.5) ng/ml versus 5.4 (1.6-47.5) ng/ml (median and range in parentheses; p < 0. 05), whereas the plasma leptin concentration was normal in hemodialysis patients. Plasma leptin was not significantly associated with the creatinine clearance in predialysis patients. In conclusion; the glomerular filtration rate seemed to have a limited influence on the plasma leptin concentration in nondiabetic uremic subjects matched by body fat mass to controls. The plasma leptin concentration was closely associated with the body fat mass, and the leptin level might, therefore, be useful as an indicator of the fat mass in nondiabetic uremic patients.     

The independent effect of propofol anesthesia on whole body protein metabolism in humans.

BACKGROUND: The purpose of this study was to examine the effect of general anesthesia with propofol in the absence of surgical stimulation on whole body protein metabolism. METHODS: Six unpremedicated patients were studied. General anesthesia included propofol (120 microg x kg(-1) x min(-1)), vecuronium bromide, and oxygen-enriched air. Changes in protein breakdown, protein oxidation, and synthesis were measured by an isotope dilution technique using a constant infusion of the stable isotope tracer L-[1-13C]leucine (0.008 mg x kg(-1) x min(-1)) before and during 100 min of propofol anesthesia. The plasma concentrations of glucose, lactate, non-esterified fatty acids, and cortisol were measured before and during anesthesia. RESULTS: An isotopic steady state of plasma [1-13C]alpha-ketoisocaproate (taken to represent the intracellular leucine precursor pool enrichment for protein synthesis) and expired 13C-carbon dioxide were obtained before and during propofol infusion. Whole body protein breakdown decreased during propofol anesthesia by 6% (P < 0.05), whereas protein synthesis and oxidation did not change significantly. Plasma concentration of cortisol decreased after 90 min of propofol anesthesia (P < 0.05). No significant changes of plasma concentrations of glucose, lactate, and non-esterified fatty acids occurred during propofol administration. CONCLUSIONS: Propofol anesthesia did not significantly affect whole body protein synthesis and oxidation but caused a small, although significant, decrease in whole body protein breakdown, possibly mediated through the suppression of plasma cortisol concentration.     

Markers of oxidative stress in cyclosporine-treated and tacrolimus-treated children after liver transplantation

Oxidative stress is presumed to have a major role in cyclosporine A (CsA)- and tacrolimus-induced tissue toxicity. The present study was performed to elucidate the degree of oxidative stress after liver transplantation in CsA- and tacrolimus-treated patients. Twenty-three patients (14 patients, CsA; 9 patients, tacrolimus) aged 2.5 to 18 years (mean, 9.8 years) who had undergone liver transplantation 1.5 to 12 years (mean, 5.4 years) before were studied. Eighteen healthy children aged 2 to 16.5 years (mean, 9.4 years) served as a control group. The following parameters were assessed: plasma lipoprotein levels; plasma carbonyl levels, as markers of oxidative damage to proteins; total plasma oxidizability, which evaluates plasma antioxidant capacity (lag phase) and lipoprotein susceptibility to oxidation; and plasma antioxidant capacity by cyclic voltammetry (CV), which measures antioxidant capacity stemming from hydrophilic low-molecular-weight antioxidant components. Carbonyl levels and rates of plasma oxidation did not differ between groups. The lag phase of plasma oxidation was significantly longer in CsA-treated children compared with tacrolimus-treated children or controls (mean, 54.4 ± 4.8 [SE] v 40.2 ± 2.2 v 46.5 ± 2.8 minutes, respectively; P < 0.05). Antioxidant capacity, assessed by CV, did not differ among CsA-treated patients, tacrolimus-treated patients, and healthy controls. Plasma α-tocopherol and β-carotene levels did not differ between CsA-treated and tacrolimus-treated patients. In children post–liver transplantation, oxidative damage assessed by markers of lipid and protein oxidation is not increased, and plasma antioxidant capacity is not diminished. (Liver Transpl 2002;8:469-475.)     

严重外科感染患者杀菌/通透性增加蛋白水平的变化规律及意义

目的观察外科严重感染患者内源性杀菌／通透性增加蛋白（BPI）的变化规律及其临床意义。方法筛选外科严重感染患者19例,分别于感染前和感染后第1、3、5、7、14天采集血标本。采用ELISA方法测定血浆BPI、脂多糖结合蛋白（LBP）和白细胞介素-6（IL-6）水平;内毒素含量采用改良基质显色法鲎试验检测。同时检查感染前及感染后第1、3、5、7、14天的中性粒细胞计数,并观察患者预后。结果与正常对照组比较,脓毒症组患者感染后第1～5天血浆中BPI／LBP比值明显降低（P〈0．01）,第7天恢复至正常范围;严重脓毒症组患者感染后第1～7天其比值显著降低（P〈0．01）。此外,感染后第1～3天严重脓毒症组血浆中BPI／LBP比值显著低于脓毒症组（P〈0．05）。结论外科感染时机体内源性BPI和LBP水平迅速升高,但BPI的增幅明显低于LBP;感染早期BPI／LBP比值与脓毒症病情的严重程度密切相关。     

The influence of gender, weight, height and BMI on pentosidine concentrations in plasma of hemodialyzed patients

BACKGROUND/AIMS: Advanced glycation end-products (AGEs) such as pentosidine play an important role in complications associated with chronic renal failure (CRF) and hemodialysis (HD). This study was undertaken to determine the influence of anthropometric parameters and inflammation on plasma pentosidine concentrations. METHODS: We measured total and free pentosidine in the plasma of 49 patients on chronic HD. Acid hydrolysis of plasma and protein precipitation with trichloroacetic acid was done in the case of total and free pentosidine, respectively. Pentosidine was measured by high performance liquid chromatography (HPLC). C-reactive protein (CRP) was measured by the nephelometric method. RESULTS: A strong negative correlation between dry weight and mean concentration of total pentosidine before and after HD was found (R = -0.47, p < 0.001). This correlation was stronger in males (R = -0.47, p = 0.017) than females (R = -0.34, p = 0.10). Even stronger correlations were noted between body mass index (BMI) and total (R = -0.55, p < 0.001), as well as free (R = -0.39, p = 0.01) pentosidine. Multivariate analysis demonstrated that BMI and time on HD were two independent factors influencing total pentosidine concentrations. CRP did not correlate with pentosidine or BMI. CONCLUSIONS: Lower BMI values are associated with significantly higher plasma pentosidine concentrations in patients on HD. Presumably this relationship is mediated by hypercatabolism observed in these patients. Catabolism produces weight loss and reduces BMI concurrently with the induction of oxidative and carbonyl stresses that stimulate the generation of pentosidine and other harmful AGEs in dialyzed patients.     

Effect of hemodialysis on protein synthesis

BACKGROUND: Earlier studies have shown that hemodialysis (HD) treatment stimulates net protein catabolism. Several factors associated with HD affect protein catabolism, such as an inflammatory effect due to blood-membrane contact and loss of amino acids and glucose into the dialysate. SUBJECTS, MATERIAL AND METHODS: We have studied protein synthesis in skeletal muscle of healthy volunteers (n = 9) before and after a single heparin-free HD. Protein synthesis (PS) was studied, using 2 independent techniques: the incorporation of labeled 2H5-phenylalanine into muscle protein, which gives a quantitative measure of the fractional synthesis rate of muscle proteins, and the concentration and size distribution of ribosomes, which gives a qualitative estimate of protein synthesis. Furthermore, free amino acid concentrations were determined in muscle and plasma. RESULTS: The rate of PS, expressed as the fractional synthesis rate, decreased by 13% during HD (p < 0.02). The capacity for PS, as reflected by the total concentration of ribosomes, was reduced by 22% (p < 0.02) and the activity of PS, expressed as the relative proportion of polyribosomes, decreased from 48.4 +/- 0.9% to 44.8 +/- 0.8% after dialysis (p < 0.01). There was a total loss of 5.8 +/- 0.3 g amino acid to the dialysate. Plasma and muscle free amino acid concentrations were determined at four time points; before and after the phenylalanine incorporation period, before dialysis and before and after the second incorporation period after dialysis. Immediately after dialysis, there was a decrease in plasma asparagine, histidine, alanine, taurine, valine and tryptophane. In muscle, no changes occurred except for a slight increase in leucine after dialysis. In blood, the glucose concentration decreased and the total amount of glucose lost to the dialysate was 21 +/- 3.0 g. In summary, one single hemodialysis treatment decreases fractional protein synthesis rate in skeletal muscle. CONCLUSION: The results demonstrate substantial losses of amino acids and glucose to the dialysate and decreased amino acid concentrations in plasma, but only minimal changes in the intracellular amino acid concentrations in muscle, suggesting that the decreased PS is caused not by lack of amino acid precursors at the site of the synthesis activity, but by other mechanisms.     

Corticosterone alone does not explain increased muscle proteolysis in septic rats

The mediators and mechanisms of muscle proteolysis in sepsis are not fully known. We investigated the role of corticosterone in increased muscle proteolysis during sepsis in rats. In one series of experiments, plasma corticosterone and total and myofibrillar protein breakdown rates, determined in incubated extensor digitorum longus muscles as release of tyrosine and 3-methylhistidine, respectively, were measured 16 hr after sham operation (control) or cecal ligation and puncture (sepsis). In other experiments, corticosterone (10 mg/100 g body wt) was injected subcutaneously twice over 16 hr; thereafter, plasma hormone levels and muscle protein breakdown rates were determined. Plasma corticosterone was increased from 14 +/- 1 micrograms/dl in control rats to 38 +/- 8 micrograms/dl in septic rats and total and myofibrillar protein breakdown rates were increased by 99 and 326%, respectively, in muscles from septic rats. When administration of corticosterone resulted in plasma levels similar to those observed in septic rats, total or myofibrillar protein breakdown rates were not altered. The results suggest that corticosterone alone is not responsible for increased muscle proteolysis in septic rats. The data, however, do not rule out the possibility that glucocorticoids may be a cofactor to some other substance or substances in the induction of muscle proteolysis during sepsis.     

Ceftriaxone Pharmacokinetics during Iatrogenic Hydroxyethyl Starch-induced Hypoalbuminemia: A Model to Explore the Effects of Decreased Protein Binding Capacity on Highly Bound Drugs

Background: Although various drugs used by anesthesiologists highly bind to plasma proteins, the impact of iatrogenically induced hypoproteinemia on their pharmacologic effects has never been investigated. The authors determined the pharmacokinetics of ceftriaxone, a cephalosporin that binds strongly to albumin in postsurgical patients with hydroxyethyl starch-induced hypoalbuminemia.

Methods: Eleven hypoalbuminemic (serum albumin < 25 g/l) patients and age (+/- 5 yr)-, sex-, and body surface area (+/- 10%)-matched healthy volunteers received a 2-g ceftriaxone dose infused over a 15-min period. Fourteen venous blood samples were collected during the 24-h study period. Free ceftriaxone concentrations were determined by ultrafiltration. Antibiotic concentrations in plasma and ultrafiltrate were measured by ion-paired reversed-phase chromatography. The pharmacokinetic parameters derived from total and free antibiotic concentrations were determined using a noncompartmental method. Data are expressed as median and range.

Results: The pharmacokinetic parameters derived from total ceftriaxone concentrations were similar for the two groups, except for the median corrected volume of distribution at steady state, which was increased (P = 0.05) to 0.18 l/kg (range, 0.11-0.29 l/kg) in patients, compared with 0.15 l/kg (range, 0.13-0.22 l/kg) in volunteers. The area under the free ceftriaxone concentration-time curve was twice as high in patients as in volunteers (median 192, range 114-301 vs. median 122, range 84-169 h [middle dot] mg-1 [middle dot] l-1;P = 0.03). Moreover, the free ceftriaxone concentration remained more than 4 mg/l during more time in patients (median, 16.7; range, 12.6-21.4 vs. median, 11.1; range, 6.0-19.0 h;P = 0.03).     

Sequential changes in the metabolic response in severely septic patients during the first 23 days after the onset of peritonitis.

OBJECTIVE: To quantify the sequential changes in metabolic response occurring in patients with severe sepsis after the onset of peritonitis. SUMMARY BACKGROUND DATA: Understanding the changes in energy expenditure and body composition is essential for the optimal management of severely septic patients; however, they have not been quantified in the context of modern surgical care. METHODS: Twelve patients with severe sepsis secondary to peritonitis (median APACHE II score = 21.5) had measurements of energy expenditure and body composition as soon as they were hemodynamically stable and 5, 10, and 21 days later. Sequential measurements of acute-phase proteins and cytokine responses were also made. RESULTS: Resting energy expenditure rose to 49% above predicted and remained elevated throughout the study period. Total energy expenditure was 1.25 x resting energy expenditure. Body fat was oxidized when energy intake was insufficient to achieve energy balance. There was a positive fluid balance of 12.5 1 over the first 2 days after onset of sepsis; thereafter, body water changes closely paralleled body weight changes and were largely accounted for by changes in extracellular water. During the 21 -day study period, there was a loss of 1.21 kg (13%) of total body protein. During the first 10 days, 67% of the protein lost came from skeletal muscle, but after this time it was predominantly from viscera. Intracellular potassium levels were low but did not deteriorate further after hemodynamic stability had been reached. There was a reprioritization of hepatic protein synthesis that was obligatory and independent of changes in total body protein. The cytokine responses demonstrated the complexity, redundancy, and overlap of mediators. CONCLUSIONS: The period of hypermetabolism in severely septic patients is similar to that previously described, but the fluid changes are larger and the protein loss is greater. Protein loss early on is predominantly from muscle, thereafter from viscera. Fat loss can be prevented and cell function preserved once hemodynamic stability is achieved.     

Plasma Protein Carbonyl and Thiol Stress Before and After Laparoscopic Gastric Banding in Morbidly Obese Patients

Background The aim of this study is to examine the relationship between oxidative plasma protein and thiol stress and weight loss after laparoscopic adjustable gastric banding (LAGB). Methods Plasma protein carbonyl (PCO) concentration as a marker of protein oxidation, plasma thiol (PSH) and erythrocyte glutathione concentration (GSH, major intracellular thiol), as an antioxidant and metabolic markers, such as Homeostatic Model Assessment – Insulin resistance (HOMA-IR), BMI and plasma lipids were determined in morbidly obese patients (n 22, mean age 34.7 ± 11 years, BMI 48.4 ± 6.4 kg/m²) at baseline and 1 and 6 months after operation. Baseline levels in patients were also compared with the levels in agematched controls (n 20, BMI 21.3 ± 1.8 kg/m²). Plasma PCO and thiols and erythrocyte GSH concentrations were determined spectrophotometrically. Results Plasma PCO were significantly higher and plasma and erythrocyte thiol concentrations were significantly lower in morbidly obese patients than in controls (for each comparison, P < 0.01). BMI, plasma triglycerides and HOMA-IR were positively correlated with plasma PCO and negatively correlated with plasma P-SH and erythrocyte GSH (for each comparison, P < 0.01). Plasma HDL-cholesterol levels were positively correlated with plasma erythrocyte GSH (r = 0.405, P < 0.01) and negative correlated with plasma PCO (r = −0.273, P < 0.01). One and 6 months after the LAGB operation, total weight loss was 13.2 ± 6.3 and 35.5 ± 7.5 kg, respectively. Plasma PCO concentrations were decreased and P-SH and erythrocyte GSH concentrations were elevated following weight loss (for each, P < 0.01). Only plasma P-SH levels were restored to the control levels 6 months after LAGB. Conclusions Obesity and insulin resistance appear to be associated with plasma protein oxidation and thiol concentrations. Protein and thiol oxidative stress was improved by weight loss after LAGB in the short-term.     

Posttranslational modifications of cardiac and skeletal muscle proteins by reactive oxygen species after burn injury in the rat.

OBJECTIVE: To determine the involvement of oxidative damage in muscle wasting after burn injury. SUMMARY BACKGROUND DATA: Burn injury damages tissue at the site of the burn and also affects peripheral tissue. There is evidence to suggest that reactive oxygen species may be generated in increased amounts after burn, and these may contribute to wound healing and to posttranslational modifications of tissue constituents distant from the wound site. METHODS: The oxidation of muscle proteins was assessed, using the dinitrophenylhydrazine assay for carbonyl content, in muscles of rats after a full-thickness skin scald burn covering 20% of the total body surface area, over a 6-week period. In this model, rats failed to incur normal body weight or muscle weight gain. RESULTS: Soleus, extensor digitorum longus, diaphragm, and heart ventricle proteins were oxidatively damaged after injury. The extent of tissue protein oxidation, however, differed depending on the time points studied. In general, higher levels of protein carbonyl group formation, an indicator of oxidative damage, were found to occur within 1 to 5 days after injury, and the oxidized protein content of the various tissues decreased during the later stages. Both sarcoplasmic and myofibrillar carbonyl-containing proteins accumulated in diaphragm 3 days after burn injury and were rapidly removed from the tissue during a 2-hour in vitro incubation. This coincided with increased proteolytic activity in diaphragm. CONCLUSIONS: These observations suggest that the loss of proteins modified by reactive oxygen species may contribute to the burn-induced protein wasting in respiratory and other muscles by a proteolytically driven mechanism.     

Bactericidal/permeability-increasing protein attenuates systemic inflammation and acute lung injury in porcine lower limb ischemia-reperfusion injury

OBJECTIVE: To investigate the role of recombinant bactericidal/permeability-increasing protein (rBPI21) in the attenuation of the sepsis syndrome and acute lung injury associated with lower limb ischemia-reperfusion (I/R) injury. SUMMARY BACKGROUND DATA: Gut-derived endotoxin has been implicated in the conversion of the sterile inflammatory response to a lethal sepsis syndrome after lower torso I/R injury. rBPI21 is a novel antiendotoxin therapy with proven benefit in sepsis. METHODS: Anesthetized ventilated swine underwent midline laparotomy and bilateral external iliac artery occlusion for 2 hours followed by 2.5 hours of reperfusion. Two groups (n = 6 per group) were randomized to receive, by intravenous infusion over 30 minutes, at the start of reperfusion, either thaumatin, a control-protein preparation, at 2 mg/kg body weight, or rBPI21 at 2 mg/kg body weight. A control group (n = 6) underwent laparotomy without further treatment and was administered thaumatin at 2 mg/kg body weight after 2 hours of anesthesia. Blood from a carotid artery cannula was taken every half-hour for arterial blood gas analysis. Plasma was separated and stored at -70 degrees C for later determination of plasma tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 by bioassay, and IL-8 by enzyme-linked immunosorbent assay (ELISA), as a markers of systemic inflammation. Plasma endotoxin concentration was measured using ELISA. Lung tissue wet-to-dry weight ratio and myeloperoxidase concentration were used as markers of edema and neutrophil sequestration, respectively. Bronchoalveolar lavage protein concentration was measured by the bicinclinoic acid method as a measure of capillary-alveolar protein leak. The alveolar-arterial gradient was measured; a large gradient indicated impaired oxygen transport and hence lung injury. RESULTS: Bilateral hind limb I/R injury increased significantly intestinal mucosal acidosis, intestinal permeability, portal endotoxemia, plasma IL-6 concentrations, circulating phagocytic cell priming and pulmonary leukosequestration, edema, capillary-alveolar protein leak, and impaired gas exchange. Conversely, pigs treated with rBPI21 2 mg/kg at the onset of reperfusion had significantly reduced intestinal mucosal acidosis, portal endotoxin concentrations, and circulating phagocytic cell priming and had significantly less pulmonary edema, leukosequestration, and respiratory failure. CONCLUSIONS: Endotoxin transmigration across a hyperpermeable gut barrier, phagocytic cell priming, and cytokinemia are key events of I/R injury, sepsis, and pulmonary dysfunction. This study shows that rBPI21 ameliorates these adverse effects and may provide a novel therapeutic approach for prevention of I/R-associated sepsis syndrome.     

Plasma adiponectin concentration in patients after successful kidney transplantation--a single-center, observational study

BACKGROUND AND AIM: Adiponectin is an anti-inflammatory protein secreted almost exclusively by adipocytes which improves insulin sensitivity and presents antiatherogenic properties. Plasma adiponectin concentration is almost 3 times higher in hemodialysis patients and markedly decreased after successful kidney transplantation. However, until now, there are no studies analyzing plasma adiponectin concentration in kidney transplant patients (KTx) during the long-term period after transplantation. Therefore, the aim of present study was to examine plasma adiponectin concentration in KTx patients during the wide range of time after transplantation. MATERIAL AND METHOD: Single center, cross-sectional study including 228 KTx adult recipients (143 M and 85 F) with estimated glomerular filtration rate (eGFR) > or = 15 ml/min, 80 hemodialysis patients (34 M and 46 F) and 52 healthy subjects (33 M and 19 F). Plasma adiponectin concentration was estimated together with HOMA-IR (homeostasis model assessment insulin resistance index) and plasma lipid profile. RESULTS: In KTx patients plasma adiponectin concentration 14.0 (13.1-15.0) microg/ml was significantly (p < 0.001), lower than in hemodialysis ones 29.0 (24.7-33.3) microg/ml, however, significantly (p < 0.001) higher than in healthy subjects 10.1 (8.8-11.5) microg/ml. Among KTx patients the highest plasma adiponectin concentration was observed in the subgroup of patients surviving with the functioning graft more than 8 years after transplantation. In KTx patients, significant, negative correlations were found between plasma adiponectin concentration and BMI (p = 0.017), HOMA-IR (p = 0.02) and estimated GFR (p < 0.009), respectively. Multiple regression analysis performed in the group of KTx patients, with plasma adiponectin concentration as the dependent variable and BMI, age, gender, estimated GFR as independent variables showed that in this model (R2 = 0.09) plasma adiponectin concentration significantly depends on BMI (p = 0.035), gender (p = 0.004) and eGFR (p = 0.023). CONCLUSIONS: Patients with long-term renal graft survival are characterized by a higher plasma adiponectin concentration. Kidney graft function (assessed as estimated GFR) is an important factor influencing plasma adiponectin concentration.     

Hemodialysis with Regenerated Cellulosic Membranes Does Not Reduce Plasma Selenium Levels in Chronic Uremic Patients

Abstract: Selenium (Se) is considered an essential and very important trace element for humans. Se blood levels are frequently low in end-stage renal disease (ESRD) patients, but very little has been established concerning the mechanisms that could modify Se status in uremia, including a supposed dialysis-mediated Se depletion. In order to verify whether hemodialysis (HD) can induce a loss of Se, thereby leading or contributing to a low plasma Se concentration, we investigated the effect of HD procedure with the most commonly used regenerated cellulosic membrane (Cuprophan) on plasma Se levels in 20 uremic patients on HD for 62.5 ± 49.4 months. Plasma Se levels were also determined in 15 chronic renal failure (CRF) nondialyzed patients and in 28 age-matched healthy controls. Se concentration was determined by atomic absorption spectrophotometry. Plasma Se levels of both HD patients (61.3 ± 8.5 μ/L) and CRF nondialyzed patients (56.4 ± 10.1 μg/L) were significantly lower than in normal subjects (78.3 ± 9.7 μg/L, p < 0.001). In CRF nondia-lyzed patients, a significant (p < 0.05) negative correlation was found between the plasma Se concentration versus serum creatinine values. Within the HD group, plasma Se levels significantly increased after the HD procedure (72.8 ± 17.2 μg/L, p < 0.02) together with hemat-ocrit and total plasma protein values (p < 0.05 and p < 0.001, respectively). In the hollow fiber dialyzer during an HD session, the Se concentration increased but not significantly from the blood inflow site (64.6 ± 12.5 μg/L) to the outflow site (72.6 ± 17 μg/L) and decreased, again not significantly, from the dialysate entrance (5 ± 1.9 μg/L) to the outlet (4.8 ± 2.5 μ?.). In HD with low-flux regenerated cellulosic dialyzer, very likely due to the high molecular weight of Se-binding proteins, the replacement treatment did not induce a Se loss in chronic uremic patients with a low plasma Se concentration.     

The Independent Effect of Propofol Anesthesia on Whole Body Protein Metabolism in Humans

Background: The purpose of this study was to examine the effect of general anesthesia with propofol in the absence of surgical stimulation on whole body protein metabolism.

Methods: Six unpremedicated patients were studied. General anesthesia included propofol (120 [micro sign]g [middle dot] kg-1 [middle dot] min (-1)), vecuronium bromide, and oxygen-enriched air. Changes in protein breakdown, protein oxidation, and synthesis were measured by an isotope dilution technique using a constant infusion of the stable isotope tracer L-[1-(13) C]leucine (0.008 mg [middle dot] kg-1 [middle dot] min-1) before and during 100 min of propofol anesthesia. The plasma concentrations of glucose, lactate, non-esterified fatty acids, and cortisol were measured before and during anesthesia.

Results: An isotopic steady state of plasma [1-(13) C] [Greek small letter alpha]-ketoisocaproate (taken to represent the intracellular leucine precursor pool enrichment for protein synthesis) and expired13 C-carbon dioxide were obtained before and during propofol infusion. Whole body protein breakdown decreased during propofol anesthesia by 6% (P < 0.05), whereas protein synthesis and oxidation did not change significantly. Plasma concentration of cortisol decreased after 90 min of propofol anesthesia (P < 0.05). No significant changes of plasma concentrations of glucose, lactate, and non-esterified fatty acids occurred during propofol administration.     

Ceftriaxone pharmacokinetics during iatrogenic hydroxyethyl starch-induced hypoalbuminemia: a model to explore the effects of decreased protein binding capacity on highly bound drugs

BACKGROUND: Although various drugs used by anesthesiologists highly bind to plasma proteins, the impact of iatrogenically induced hypoproteinemia on their pharmacologic effects has never been investigated. The authors determined the pharmacokinetics of ceftriaxone, a cephalosporin that binds strongly to albumin in postsurgical patients with hydroxyethyl starch-induced hypoalbuminemia. METHODS: Eleven hypoalbuminemic (serum albumin < 25 g/l) patients and age (+/- 5 yr)-, sex-, and body surface area (+/- 10%)-matched healthy volunteers received a 2-g ceftriaxone dose infused over a 15-min period. Fourteen venous blood samples were collected during the 24-h study period. Free ceftriaxone concentrations were determined by ultrafiltration. Antibiotic concentrations in plasma and ultrafiltrate were measured by ion-paired reversed-phase chromatography. The pharmacokinetic parameters derived from total and free antibiotic concentrations were determined using a noncompartmental method. Data are expressed as median and range. RESULTS: The pharmacokinetic parameters derived from total ceftriaxone concentrations were similar for the two groups, except for the median corrected volume of distribution at steady state, which was increased (P = 0.05) to 0.18 l/kg (range, 0. 11-0.29 l/kg) in patients, compared with 0.15 l/kg (range, 0.13-0.22 l/kg) in volunteers. The area under the free ceftriaxone concentration-time curve was twice as high in patients as in volunteers (median 192, range 114-301 vs. median 122, range 84-169 h. mg-1. l-1;P = 0.03). Moreover, the free ceftriaxone concentration remained more than 4 mg/l during more time in patients (median, 16. 7; range, 12.6-21.4 vs. median, 11.1; range, 6.0-19.0 h; P = 0.03). CONCLUSIONS: Compared with healthy volunteers, patients with iatrogenic hypoalbuminemia have higher free ceftriaxone concentrations during the 24 h after antibiotic administration. This modification increases drug distribution into extravascular space and may enhance effectiveness.