Possible role of TNF on procalcitonin release in a baboon model of sepsis.

Procalcitonin (PCT) has been described as an early and discriminating marker of bacteria-associated sepsis in patients. However, little is known of its source and actions, especially with regard to its relation to tumor necrosis factor (TNF). TNF is responsible for the release of several other mediators of sepsis e.g., chemokines. We tested the hypothesis that plasma PCT levels during sepsis differ with regard to the degree of TNF availability. Severe hyperdynamic sepsis was induced in baboons (n = 14) by i.v. infusion of live E. coli (approximately 2 x 10(9) colony-forming units/kg) over 2 h. Animals were pretreated 2 h before E. coli either with 1 mg/kg humanized anti-TNF antibody (CDP571) or placebo (Ringer solution). Plasma PCT levels at baseline was barely detectable, but increased to about 4000 pg/mL at 4 h after E. coli infusion. Levels were maximal between 8 and 24 h and had returned nearly to baseline at 72 h. Although no TNF could be measured in the treated group, PCT levels were not different between the placebo and the TNF antibody treatment group. We conclude that PCT levels are not dependent on the systemic presence of TNF in an E. coli sepsis model in baboons. Such sepsis induced PCT release is clearly different from the previously reported PCT release during infusion of rhTNF in volunteers or chimpanzees.

Procalcitonin release patterns in a baboon model of trauma and sepsis: relationship to cytokines and neopterin.

OBJECTIVES: Procalcitonin (PCT) has been described as an early, discriminating marker of bacteria-associated sepsis in patients. However, little is known of its source and actions, in part because no appropriate animal models have been available. We tested the hypothesis that plasma PCT increases during various pathophysiological conditions, such as hemorrhagic shock and sepsis, which differ with regard to the degree of associated endotoxemia. We further hypothesized that in sepsis, PCT would be significantly different in survivors vs. nonsurvivors. DESIGN: Prospective, blinded analysis of previously collected plasma of experimental animals. SETTING: Independent nonprofit research laboratory in a trauma hospital and a contract research institute. SUBJECTS: A total of 22 male baboons (17.5-31 kg). INTERVENTIONS: Hemorrhagic-traumatic shock was induced by hemorrhage for up to 3 hrs, reperfusion with shed blood and infusion of cobra venom factor (n = 7). By using a similar experimental setup, severe hyperdynamic sepsis was induced (n = 15) by intravenous infusion of live Escherichia coli (2 x 10(9) colony-forming units/kg) over 2 hrs, followed by antibiotic therapy (gentamicin 4 mg/kg twice a day). MEASUREMENTS AND MAIN RESULTS: Plasma PCT at baseline was barely detectable, but levels increased significantly (p < .05) to 2+/-1.8 pg/mL 2 hrs after the start of reperfusion in the shock group, and to 987+/-230 pg/mL at 4 hrs after E. coli in the sepsis group. Levels were maximal between 6 and 32 hrs and had returned nearly to baseline levels at 72 hrs. Interleukin-6 levels paralleled the course of PCT measurements, whereas a significant increase in neopterin was seen at 24 hrs. PCT levels were approximately three times higher in the sepsis group than in the shock group, corresponding to endotoxin levels (at the end of hemorrhage, 286+/-144 pg/mL vs. 3576+/-979 pg/mL at the end of E. coli infusion; p = .003). PCT levels were significantly different at 24 hrs between survivors (2360+/-620 pg/mL) and nonsurvivors (4776+/-563 pg/mL) in the sepsis group (p = .032), as were interleukin-6 (1562+/-267 vs. 4903+/-608 pg/mL; p = .01) and neopterin/creatinine ratio (0.400+/-0.038 vs. 0.508+/-0.037; p = .032). CONCLUSIONS: PCT is detectable in the baboon as in humans, both in hemorrhagic shock and sepsis. PCT levels are significantly higher in sepsis than in hemorrhage, a finding that is probably related to the differences in endotoxin. The baboon can be used for the study of PCT kinetics in both models; PCT kinetics are clearly different from other markers of sepsis, either IL-6 or neopterin, in both models. There are significant differences between survivors and nonsurvivors in the sepsis model.

Procalcitonin (PCT) is useful in predicting the bacterial origin of an acute circulatory failure in critically ill patients.

OBJECTIVE: To evaluate the accuracy of procalcitonin (PCT) in predicting bacterial infection in ICU medical and surgical patients. SETTING: A 10-bed medical surgical unit. DESIGN: PCT, C-reactive protein (CRP), interleukin 6 (IL-6) dosages were sampled in four groups of patients: septic shock patients (SS group), shock without infection (NSS group), patients with systemic inflammatory response syndrome related to a proven bacterial infection (infect. group) and ICU patients without shock and without bacterial infection (control group). RESULTS: Sixty patients were studied (SS group:n=16, NSS group,n=18, infect. group,n=16, control group,n=10). The PCT level was higher in patients with proven bacterial infection (72+/-153 ng/ml vs 2.9+/-10 ng/ml,p=0.0003). In patients with shock, PCT was higher when bacterial infection was diagnosed (89 ng/ml+/-154 vs 4.6 ng/ml+/-12,p=0.0004). Moreover, PCT was correlated with severity (SAPS:p=0.00005, appearance of shock:p=0.0006) and outcome (dead: 71.3 g/ml, alive: 24.0 g/ml,p=0.006). CRP was correlated with bacterial infection (p<10(-5)) but neither with SAPS nor with day 28 mortality. IL-6 was correlated with neither infection nor day 28 mortality but was correlated with SAPS. Temperature and white blood cell count were unable to distinguish shocked patients with or without infection. Finally, when CRP and PCT levels were introduced simultaneously in a stepwise logistic regression model, PCT remained the unique marker of infection in patients with shock (PCT> or =5 ng/ml, OR: 6.2, 95% CI: 1.1-37,p=0.04). CONCLUSION: The increase of PCT is related to the appearance and severity of bacterial infection in ICU patients. Thus, PCT might be an interesting parameter for the diagnosis of bacterial infections in ICU patients.

A new approach for clinical biological assay comparison and standardization: application of principal component analysis to a multicenter study of twenty-one carcinoembryonic antigen immunoassay kits.

BACKGROUND: Principal component analysis (PCA) is a powerful mathematical method able to analyze data sets containing a large number of variables. To our knowledge, this method is applied here for the first time in the field of medical laboratory analysis. METHODS: PCA was used to evaluate the results of a blind comparative study of 21 carcinoembryonic antigen (CEA) reagent kits used to determine CEA concentration in a panel of sera from 80 patients. RESULTS: The mathematical technique first eliminated the variations attributable to the use of different calibrators. The PCA representation then gave a global view of the dispersion of the kits and allowed the identification of a main homogeneous group and of some discrepant kits. CONCLUSIONS: PCA applied to the in vitro diagnostic reagent field could contribute to the standardization process and improve the quality of medical laboratory analyses. A standardization method using a panel of patient sera is proposed.

Procalcitonin is a marker of severity of renal lesions in pyelonephritis.

OBJECTIVE: In an attempt to differentiate acute pyelonephritis from lower urinary tract infection (UTI), we measured serum procalcitonin levels, a recently described marker of infection. We compared it with other commonly used inflammatory markers and evaluated its ability to predict renal involvement as assessed by dimercaptosuccinic acid (DMSA) scintigraphy. METHODS: Serum C-reactive protein, leukocyte counts, and procalcitonin levels were measured in 80 children, 1 month to 16 years of age, admitted for suspected pyelonephritis. Renal involvement was assessed by 99mTe-DMSA scintigraphy in the first 5 days after admission. The examination was repeated at least 3 months later if the first result was abnormal. RESULTS: In lower UTI, the mean procalcitonin (PCT) was 0.38 micrograms/L +/- 0.19 compared with 5.37 micrograms/L +/- 1.9 in pyelonephritis. In these two groups, respectively, leukocyte counts were 10939/mm3 +/- 834 and 17429/mm3 +/- 994, and C-reactive protein (CRP) levels were 30.3 mg/L +/- 7.6 and 120.8 mg/L +/- 8.9. When inflammatory markers were correlated to the severity of the renal lesion as ranked by DMSA scintigraphy, we found a highly significant correlation with plasma levels of PCT, but borderline significance with CRP and none with leukocyte counts. Patients without vesicoureteral reflux had a mean PCT of 5.16 micrograms/L +/- 2.33, which was not significantly different from that in patients with reflux who had a mean PCT of 5.76 micrograms/L +/- 3.49. For the prediction of renal lesions at admission, CRP had a sensitivity of 100% and a specificity of 26.1%. The sensitivity and specificity of PCT were 70.3% and 82.6%, respectively. CONCLUSION: We conclude that serum PCT levels were increased significantly in children with febrile UTI when renal parenchymal involvement (assessed by DMSA scintigraphy) was present and allowed for prediction of patients at risk of severe renal lesions.

[Procalcitonin in severe trauma]. / La procalcitonine dans les traumatismes sévères.

The diagnosis of infection in systemic inflammatory syndrome response is difficult but essential for correct patient management. Procalcitonin is a new biochemical marker of infection especially for bacterial infection. Procalcitonin and C-reactive protein (CRP) were prospectively studied in 21 severe trauma patients and correlated with the trauma severity and the occurrence of infection. At the early post-traumatic period (admission to day 3) procalcitonin and CRP are correlated with the severity of trauma (early volume loading and markers of tissue injury) as did typically acute inflammatory proteins. At the late post-traumatic period (day 7) while CRP concentrations remain elevated in all patients, procalcitonin concentrations are only raised in septic patients even if inflammation's clinical signs persist.

[Procalcitonin, C-reactive protein and interleukin 6 in bacterial and viral meningitis in children]. / Procalcitonine, protéine C-réactive et interleukine 6 dans les méningites bactériennes et virales de l'enfant.

OBJECTIVES: In young children with meningitis, blood or cerebrospinal fluid (CSF) analysis cannot differentiate all cases of viral meningitis (VM) from bacterial meningitis (BM). Empirical antibiotic therapy is often given. As new markers are needed, we compared serum proCalcitonin (PCT) with CSF analysis for C-reactive protein (CRP) and interleukin-6 (IL6). PATIENTS AND METHODS: PCT was measured with a chemoluminescent assay in the sera of 23 children (aged 3 months to 14 years) hospitalized for BM and in 51 patients with VM. RESULTS: Initial CRP (mean 143.3 mg/l, range 28-351 and mean 13.9, range 1-48), CSF proteins (mean 2.2, range 0.4-4.74 and mean 0.57, range 0.12-2.72) and white blood cell count in CSF (range 240-17500 and 20-3200) in BM and VM respectively, were not sufficiently discriminative to distinguish between BM and VM. Twenty-four of the 51 patients with VM were given antibiotics. IL6 values at admission showed an overlap zone (> 100 pg/ml in 7/19 patients with VM and < 100 pg/ml in 1/8 patients with BM. PCT was discriminative in all cases: mean PCT in BM was 61 micrograms/l (range 4.8-335) and 0.33 in VM (range 0-1.7; p < 0.001). No production of PCT was detected in CSF. After antibiotic therapy, PCT decreased and reached undetectable levels after recovery. CONCLUSION: PCT is a sensitive and specific marker for early diagnosis of viral meningitis versus bacterial meningitis in children.

Procalcitonin and C-reactive protein during the early posttraumatic systemic inflammatory response syndrome.

OBJECTIVES: To describe the initial evolution of serum procalcitonin (PCT) and C-reactive protein (CRP) in previously healthy adult trauma patients and to compare the relationship of the expression of these two proteins with indicators of trauma severity. DESIGN: Prospective, descriptive, longitudinal study. SETTING: Surgical ICU in an university hospital. PATIENTS: Twenty-one patients admitted during the first posttraumatic 3 h exhibiting an Injury Severity Score (ISS) between 16 and 50 were enrolled. MEASUREMENTS: Blood sampling was performed on admission and on posttraumatic days 0.5, 1, 2 and 3 to assess serum levels of PCT and CRP. Total creatine kinase (CKtot) and lactate dehydrogenase (LDHtot) activities in the serum were used as tissue damage indicators. RESULTS: PCT exhibited an early and transient increase in serum levels similar to a more delayed change of CRP levels. Peak PCT and peak CRP were related to the ISS, the extent of tissue damage and the amount of fluid replacement during the first day. During the first 3 posttraumatic days, 90% of the patients exhibited a generalized inflammatory syndrome without infection. CONCLUSIONS: An early and transient release of PCT into the circulation was observed after severe trauma and the amount of circulating PCT seemed proportional to the severity of tissue injury and hypovolemia, yet unrelated to infection. The predictive value of both PCT and CRP for a forthcoming multiple organ failure still remains to be clarified.

[Procalcitonin, a marker of bacterial meningitis in children]. / La procalcitonine, indicateur d'infection bactérienne dans les méningites de l'enfant.

Procalcitonin (PCT) is a new marker connected to systemic bacterial infection. Blood values are parallel to the severity of the disease. In the present Knowledge on PCT, the usefulness is focused on acute pediatric pathology, ICU, and the follow up of grafts and surgery. This paper dwells on the interest in the differential diagnosis for meningitis (viral versus bacterial). At the opposite of CRP and IL6, a very clear cut off for all the cases has been found. The cut off in this study is about 2-3 micrograms/l. PCT, at the difference of cytokines is a very stable molecule in the blood sample. Also a very small quantity of serum (or plasma) 20 microliters is sufficient for one assay. In the future, a point of care assay will be available and should be very interesting in the emergency wards (pediatric or adult ICU). The origin of PCT seems to be--but perhaps not exclusively--mononuclear cells. The absence of an animal model (except monkeys) is actually a difficulty to progress.

Procalcitonin as a marker of bacterial sepsis in patients infected with HIV-1.

Procalcitonin (ProCT) is a recently described marker of severe sepsis. It was decided to assess the value of proCT as a marker of secondary infection in patients infected with HIV-1. ProCT plasma levels were measured by immunoluminometric assay in a prospective study in 155 HIV-infected individuals: 102 asymptomatic and 53 with lever or suspected secondary infections. The baseline plasma level of ProCT was low (0.5 ng/ml +/- 0.37), even in the latest stages of the disease, and did not differ from the values of healthy subjects (0.54 ng/ml +/- 0.08). EDTA-treated whole blood was collected from patients before starting specific antimicrobial therapy. No elevation of ProCT level was detected in HIV-infected patients with evolving secondary infections including PCP (n = 4), cerebral toxoplasmosis (n = 4), viral infections (n = 9), mycobacterial infections (n = 5), localized bacterial (n = 12) and fungal infections (n = 4), malignancies (n = 3), and in various associated infectious and non-infectious febrile events (n = 13). All these plasma values were lower than 2.1 ng/ml. In contrast, high ProCT plasma levels were detected in one HIV-infected patient with a septicaemic Haemophilus influenzae infection (16.5 ng/ml) and another one with a septicaemic Pseudomonas aeruginosa infection (44.1 ng/ ml), ProCT values decreased rapidly under appropriate therapy. ProCT seems to be a specific marker of bacterial sepsis in HIV-infected patients, as no increase in other secondary infections could be detected in those patients. A rapid determination of ProCT level could be useful to confirm or refute bacterial sepsis for a better management of febrile HIV-infected patients.

Measurement of procalcitonin levels in children with bacterial or viral meningitis.

We measured the plasma procalcitonin levels in 59 children who were admitted to the hospital because of bacterial or viral meningitis. Eighteen children with acute bacterial meningitis had elevated procalcitonin levels (mean level, 54.5 micrograms/L; range, 4.8-110 micrograms/L). The procalcitonin levels in 41 children with viral meningitis were low (mean level, 0.32 micrograms/L; range, 0-1.7 micrograms/L; P < .0001). Assay of cerebrospinal fluid (CSF) cells and proteins and serum C-reactive protein showed a zone of overlapping values between the two groups. Procalcitonin was not produced in CSF. Plasma procalcitonin levels decreased rapidly during antibiotic therapy. These data suggest that the measurement of plasma procalcitonin might be of value in the differential diagnosis of meningitis due to either bacteria or viruses.

Evolution and significance of circulating procalcitonin levels compared with IL-6, TNF alpha and endotoxin levels early after thermal injury.

To determine the evolution and significance of circulating procalcitonin (ProCT), IL-6 TNF alpha and endotoxin levels early after thermal injury, we performed a prospective, single unit, longitudinal study. Forty burn patients with total body surface area (TBSA) > 30 per cent were studied, of whom 33 suffered an inhalation injury. Blood samples were taken on the day of admission, every 4 h during the first day and daily during the first week. All patients had increased ProCT and IL-6 levels without any proven infection. Endotoxin and TNF alpha levels remained very low or undetectable. ProCT and IL-levels correlated well with the severity of skin burn injury (respectively, p < 0.006 and p < 0.028, using the non-parametric Kruskal-Wallis test). ProCT levels are not associated with smoke inhalation. ProCT and IL6 are prognostic factors of mortality at the time of admission but less reliable than the clinical UBS (unit burn standard) score. Endotoxin and TNF alpha were undetectable, suggesting that the problem of the early gut bacterial translocation remains to be proven.

Cytokines, nitrite/nitrate, soluble tumor necrosis factor receptors, and procalcitonin concentrations: comparisons in patients with septic shock, cardiogenic shock, and bacterial pneumonia.

OBJECTIVES: To determine and compare the respective concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, soluble TNF receptors, nitrite/nitrate (NO2-/NO3-), and procalcitonin in the plasma of patients with septic shock, cardiogenic shock, and bacterial pneumonia without shock; and to assess the predictive value of these mediators in defining patients with septic shock. DESIGN: Cohort study, comparing normal volunteers (controls) and patients with septic shock, cardiogenic shock, and bacterial pneumonia. SETTING: A collaborative study among an intensive care unit, an emergency room, and three research laboratories. PATIENTS: Mediators were measured at various times in 15 patients with septic shock (during the shock phase and during the recovery phase), in seven patients with cardiogenic shock during the shock phase, and in seven patients with severe bacterial pneumonia on day 1 of admission. INTERVENTIONS: Blood samples were collected at various times during the course of the disease. MEASUREMENTS AND MAIN RESULTS: TNF-alpha values were highest in the acute phase of septic shock (53 to 131 pg/mL during septic shock), while patients with bacterial pneumonia had intermediate concentrations (32 pg/mL). TNF-alpha concentrations were normal in patients with cardiogenic shock. IL-6 concentrations were highest in patients with acute septic shock (85 to 385 pg/mL). However, in contrast to TNF-alpha concentrations, IL-6 concentrations were normal in patients with bacterial pneumonia and increased in patients with cardiogenic shock (78 pg/mL). Soluble TNF receptors were increased in all three groups vs. controls, with the highest increase in patients with septic shock. NO2-/NO3- concentrations were highest (72 to 140 mM) in patients with septic shock, and were < 40 mM in the other groups of patients. Procalcitonin concentrations were only markedly increased in patients with septic shock (72 to 135 ng/mL, compared with approximately 1 ng/mL in the three other groups). The best predictive value for septic shock was found to be the measurements of NO2-/NO3- and procalcitonin concentrations. CONCLUSIONS: These observations showed that increase of proinflammatory cytokines was a consequence of inflammation, not of shock. In this study comparing various shock and infectious states, measurements of NO2-/NO3- concentration and procalcitonin concentration represented the most suitable tests for defining patients with septic shock.

Procalcitonin as a marker for the early diagnosis of neonatal infection.

Serum procalcitonin was determined in newborn infants at the time of admission to the pediatrics or obstetrics unit. Increased levels were found in all neonates with bacterial sepsis. Neonates with viral infection, bacterial colonization, or neonatal distress had normal or slightly increased levels. These data suggest that procalcitonin might be of value in diagnosing neonatal sepsis.

The role of histidine 231 in thermolysin-like enzymes. A site-directed mutagenesis study.

In the zinc metallopeptidases produced by the genus Bacillus, an active site histidine has been proposed to either stabilize the transition state in catalysis by donating a hydrogen bond to the hydrated peptide (Matthews, B. W. (1988) Acc. Chem. Res. 21, 333-340) or to polarize a water molecule, which subsequently attacks the peptidyl bond (Mock, W. L., and Aksamawati, M. (1994) Biochem. J. 302, 57-68). Site-directed mutagenesis techniques have been used to change this residue in the zinc endopeptidase from Bacillus stearothermophillus to either phenylalanine or alanine. At pH 7.0, the kcat/Km values of the substrate leucine enkephalin for the phenylalanine and alanine mutants were reduced by factors of 430- and 500-fold, respectively, as compared with the wild-type enzyme, mostly due to changes in kcat. In addition, the enzymatic activities of the mutant enzymes showed little pH dependence in the alkaline range, unlike the wild-type enzyme. The mutations did not greatly alter the binding affinities of inhibitors containing sulfydryl groups to chelate the active site zinc, while those of inhibitors containing hydroxamate or carboxylate zinc-chelating groups were increased between 80- and 250-fold. The largest change in the binding affinity of an inhibitor (> 5 orders of magnitude) was found with the proposed transition state mimic, phosphoramidon. The results are generally in agreement with x-ray crystallography studies and favor the involvement of the active site histidine in transition state binding.

Elevated serum procalcitonin levels in patients with melioidosis.

The prognostic value of serum procalcitonin levels in 43 patients with acute melioidosis, an infection with a wide range of clinical manifestations, was assessed. In eight patients with mild localized infections, the median procalcitonin levels were 0.13 ng/mL (range, 0.02-0.46 ng/mL), which were similar to those in 19 healthy controls (median, 0.07 ng/mL; range, 0.03-0.15 ng/mL). In the patients with severe infections, the initial procalcitonin levels were significantly higher in the patients who died (median, 350 ng/mL; range, 63-3,538 ng/mL) than in the survivors (median, 19 ng/mL; range, 0.55-387 ng/mL) (P < .0001); 16 of 19 patients with procalcitonin levels of > 100 ng/mL died, compared with 2 of 16 patients with levels of < 100 ng/mL (relative risk, 6.7; 95% confidence interval, 1.8-25; P = .0001). In those patients who survived, the subsequent procalcitonin levels reflected closely the clinical course of their infection. The serum concentration of procalcitonin correlates well with the severity of Pseudomonas pseudomallei infection and is comparable with other acute-phase markers. However, this prognostic indicator and marker of continuing disease activity is not specific to melioidosis and could be applied to other severe infections.