Changes of para-, meta- and ortho-tyrosine over time in burned patients.

PURPOSE: Serious burn injury leads to oxidative stress resulting in production of meta- and ortho-tyrosine, while para-tyrosine is the physiological isoform. Our aim was to investigate the metabolism of these tyrosine isoforms following major burn injury. METHODS: Fifteen patients requiring intensive care were followed for 5 consecutive days after major burn injury. Serum and urine concentrations of para-, meta-, and ortho-tyrosine were measured with high performance liquid chromatography. Fifteen healthy matching individuals were invited as control group. RESULTS: Median serum concentration of normal isoform para-tyrosine decreased in burned patients between days 2 and 5 (p < 0.01). Mean meta-, and ortho-tyrosine levels were significantly higher in patients compared to controls in the same time period (p < 0.05). Renal excretion of para-tyrosine increased significantly in our observation period (p < 0.01). CONCLUSIONS: Pathologic isoforms of tyrosine accumulate in serum meanwhile the level of normal isoform decreases possibly due to belated enhanced renal excretion or, to decreased synthesis after major burn injury.

Can leukocyte antisedimentation rate (LAR) predict septic complications and critical care survival early in polytrauma and burn victims?

BACKGROUND: In polytrauma and burn injury Systemic Inflammatory Response Syndrome (SIRS) develops. SIRS is presented in many hospitalized patients, including those who never develop infection or sepsis. Both in SIRS and sepsis the leukocyte activation occurs. In acute phase reaction leukocytes' upward flotation i.e. leukocyte antisedimentation rate (LAR) can indicate infectious origin. OBJECTIVE: To evaluate the predictive power of LAR, serum C-reactive protein (CRP) and procalcitonin (PCT) levels regarding mortality risk and development of septic complications. METHODS: In a prospective, observational study, 36 patients were followed for 5 days (T1-T5) after admission to a critical care unit immediately with severe polytrauma or burn injury. Eleven patients developed septic complications, their LAR, CRP and PCT levels were analyzed before and after 3 days of sepsis was declared. RESULTS: Ten patients died due to septic complications. In survivors LAR at T1 (p < 0.001) and T2 (p < 0.001) as well as CRP at T1 (p < 0.05) were significantly higher compared to controls and non survivors. In septic patients LAR (p < 0.05) and CRP (p < 0.05) showed a significant drop one day before sepsis was declared. PCT levels failed to predict this. CONCLUSIONS: Drop in LAR and CRP levels may be warning signs regarding the onset of septic complications after severe polytrauma and burn injury.

Role of Tyrosine Isomers in Acute and Chronic Diseases Leading to Oxidative Stress - A Review.

Oxidative stress plays a major role in the pathogenesis of a variety of acute and chronic diseases. Measurement of the oxidative stress-related end products may be performed, e.g. that of structural isomers of the physiological para-tyrosine, namely meta- and ortho-tyrosine, that are oxidized derivatives of phenylalanine. Recent data suggest that in sepsis, serum level of meta-tyrosine increases, which peaks on the 2(nd) and 3(rd) days (p<0.05 vs. controls), and the kinetics follows the intensity of the systemic inflammation correlating with serum procalcitonin levels. In a similar study subset, urinary meta-tyrosine excretion correlated with both need of daily insulin dose and the insulin-glucose product in non-diabetic septic cases (p<0.01 for both). Using linear regression model, meta-tyrosine excretion, urinary meta-tyrosine/para-tyrosine, urinary ortho-tyrosine/para-tyrosine and urinary (meta- + orthotyrosine)/ para-tyrosine proved to be markers of carbohydrate homeostasis. In a chronic rodent model, we tried to compensate the abnormal tyrosine isomers using para-tyrosine, the physiological amino acid. Rats were fed a standard high cholesterol-diet, and were given para-tyrosine or vehicle orally. High-cholesterol feeding lead to a significant increase in aortic wall meta-tyrosine content and a decreased vasorelaxation of the aorta to insulin and the glucagon-like peptide-1 analogue, liraglutide, that both could be prevented by administration of para-tyrosine. Concluding, these data suggest that meta- and ortho-tyrosine are potential markers of oxidative stress in acute diseases related to oxidative stress, and may also interfere with insulin action in septic humans. Competition of meta- and ortho-tyrosine by supplementation of para-tyrosine may exert a protective role in oxidative stress-related diseases.

Time courses of changes of para-, meta-, and ortho-tyrosine in septic patients: A pilot study.

OBJECTIVES: Sepsis is associated with oxidative stress. Due to oxidative stress, three tyrosine isoforms, para-, meta-, and ortho-tyrosine (p-, m-, and o-Tyr), can be formed non-enzymatically in smaller amounts. p-Tyr is mainly formed physiologically in the kidneys through the activity of the phenylalanine hydroxylase enzyme. The three tyrosine isoforms may undergo different renal handling. METHODS: Twenty septic patients were involved in the study and 25 healthy individuals served as controls. Blood and urine levels of p-, m-, and o-Tyr were measured on admission and four consecutive days. RESULTS: Serum m-Tyr levels were higher in septic patients than in controls on days 2 (P = 0.031) and 3 (P = 0.035). Serum p-Tyr levels were lower in the cases than in controls on days 1 (P = 0.005) and 2 (P = 0.040), and subsequently normalized due to a day-by-day elevation (P = 0.002). The tendency of urinary m-Tyr concentration was decreasing (P = 0.041), while that of urinary p-Tyr concentration was increasing (P = 0.001). Fractional excretion of m-Tyr (FEm-Tyr) showed a decreasing tendency (P = 0.009), and was, on all days, higher than FEp-Tyr, which remained near-normal, less than 4%. Procalcitonin showed significant correlation with FEm-Tyr (r = 0.454; P < 0.001). DISCUSSION: Our data suggest that the oxidative stress marker m-Tyr and physiologic p-Tyr may be handled differently in septic patients. The excretion of m-Tyr correlates with inflammation. m-Tyr may be actively secreted or produced in the kidney in some patients, whereas the decreased serum level of p-Tyr is a consequence of diminished renal production and not of renal loss.

Insulin Therapy of Nondiabetic Septic Patients Is Predicted by para-Tyrosine/Phenylalanine Ratio and by Hydroxyl Radical-Derived Products of Phenylalanine.

Hydroxyl radical converts Phe to para-, meta-, and ortho-Tyr (p-Tyr, m-Tyr, o-Tyr), while Phe is converted enzymatically to p-Tyr in the kidney and could serve as substrate for gluconeogenesis. Pathological isoforms m- and o-Tyr are supposed to be involved in development of hormone resistances. Role of Phe and the three Tyr isoforms in influencing insulin need was examined in 25 nondiabetic septic patients. Daily insulin dose (DID) and insulin-glucose product (IGP) were calculated. Serum and urinary levels of Phe and Tyr isoforms were determined using a rpHPLC-method. Urinary m-Tyr/p-Tyr ratio was higher in patients with DID and IGP over median compared to those below median (P = 0.005 and P = 0.01, resp.). Urinary m-Tyr and m-Tyr/p-Tyr ratio showed positive correlation with DID (P = 0.009 and P = 0.023, resp.) and with IGP (P = 0.004 and P = 0.008, resp.). Serum Phe was a negative predictor, while serum p-Tyr/Phe ratio was positive predictor of both DID and IGP. Urinary m-Tyr and urinary m-Tyr/p-Tyr, o-Tyr/p-Tyr, and (m-Tyr+o-Tyr)/p-Tyr ratios were positive predictors of both DID and IGP. Phe and Tyr isoforms have a predictive role in carbohydrate metabolism of nondiabetic septic patients. Phe may serve as substrate for renal gluconeogenesis via enzymatically produced p-Tyr, while hydroxyl radical derived Phe products may interfere with insulin action.

Dynamic changes of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 after burn injury.

PURPOSE: Severe burn is a life-threatening condition. Many trials discuss the role of matrix metalloproteinases and tissue inhibitor of metalloproteinases in diseases generating systemic inflammatory response syndrome, and in some, their prognostic importance has been established. We aimed to describe the time courses of the aforementioned system and to evaluate the difference between survivors and nonsurvivors in burns. MATERIALS: Thirty-one patients were enrolled. Blood samples were collected on admission and on the 5 consecutive days. Circulating matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) have been measured. Healthy individuals were invited as controls. RESULTS: Tissue inhibitor of metalloproteinase 1 increased in the burn group (P < .001) by day 2 and remained elevated thereafter. Plasma MMP-9 and MMP-9/TIMP-1 were already elevated on admission (P < .001) and decreased in tendency thereafter. In burned patients, significantly lower MMP-9 were noted on days 4 to 6 as MMP-9/TIMP-1 were also lower on days 3 to 6 (P < .01) compared with controls. We experienced difference regarding survival on days 5 and 6 by TIMP-1 (P < .05). CONCLUSIONS: Our research is the first follow-up study elucidating the dynamic changes of MMP-9-TIMP-1 system in severe burns. Alteration of MMP-9-TIMP-1 balance might influence systemic inflammatory response and related mortality. Matrix metalloproteinase 9 might be a good injury marker in burns after an extensive trial.

Time course of CD marker expression in patients with burns and its prognostic value.

INTRODUCTION: Due to immune suppression sepsis has remained the leading cause of mortality after burns. CD marker expression in circulating blood has not been fully examined in humans. The aim of our study was to asses CD marker expression after burns and to compare it between survivors and non-survivors. PATIENTS AND METHODS: Blood samples from all patients (n = 35) receiving intensive care treatment with more than 20% burned surface area were collected on admission and 5 consecutive days thereafter. Expressions of CD11a, CD11b, CD18, CD49d, CD97 and CD14 were measured on granulocytes, lymphocytes and monocytes. RESULTS: Expressions of granulocytes CD11a (days 1-2), CD18 (day 1), lymphocytes CD11a (days 1-5), CD11b (days 2-4), CD18 (days 1-6), CD49d (days 1-6), CD97 (day 1), monocytes CD11a (days 1-6), CD11b (day 2 and 5-6), CD18 (days 1-6), CD49d (days 1-6), CD97 (days 1-2), and CD14 (days 4-6) were significantly lower in patients than in healthy controls. Expressions of granulocyte CD11a (days 3-6), lymphocytes CD11a (days 3-6), CD11b (days 4-6), CD18 (days 4-6), monocyte CD97 (days 3-6) were significantly higher in survivors (n = 20) than in non-survivors (n = 15). CONCLUSION: These results suggest that burns is associated with immunosuppression and overwhelming anti-inflammatory processes may be signs of bad prognosis.