Molecular aspects and natural source of procalcitonin

Cardiorenal biomarkers in acute heart failure

Managing patients with heart failure (HF) is a challenging task within itself, but the presence of associated worsening renal function can greatly increase mortality and morbidity. Early diagnosis and treatment is the key to prevent re-hospitalizations and reduce healthcare costs. Biomarkers have long been established as highly sensitive and specific tools in diagnosing and prognosticating patients with HF. Reflecting distinct pathophysiological events and ongoing cellular insult, biomarkers have been proven superior to conventional laboratory tests. Availability of better assays and rapid analysis has allowed the use of biomarkers as point-of-care tests in the emergency department and at the patient's bed-side. Acute HF patients often go on to develop worsening renal function, termed as acute cardiorenal syndrome. The growing breadth of studies has shown the implications of combining multiple biomarkers to better chart outcomes and produce desirable results in such patients.

Central administration of aminoprocalcitonin inhibits food intake and stimulates the hypothalamic-pituitary-adrenal axis in rats via the corticotrophin-releasing factor system

Aminoprocalcitonin (N-PCT), a neuroendocrine peptide derived from procalcitonin, reduces food intake and body weight when administered centrally in rats. We have recently shown that N-PCT is expressed in brain areas known to be involved in energy homeostasis, including the paraventricular nucleus (PVN) of the hypothalamus, which contains a prominent population of corticotrophin-releasing factor (CRF)-synthesising neurones. CRF plays a pivotal role in the regulation of the hypothalamic-pituitary adrenal (HPA) axis and food intake. However, little is known about functional interactions of N-PCT and CRF. In the present study, we found endogenous N-PCT protein in the rat PVN. We also showed N-PCT immunoreactivity in PVN co-localised with NeuN, a neuronal marker, or glial fibrillary acidic protein, an astrocyte marker. Double staining immunohistochemistry revealed that N-PCT co-localised with CRF in parvocellular neurones of the PVN. Intracerebroventricular N-PCT administration increased CRF mRNA and content in the hypothalamus, suggesting that N-PCT stimulates the HPA axis and suppresses food intake and body weight via CRF-dependent pathways. In keeping with this, i.c.v. co-injection of D-Phe-CRF(12-41), a CRF receptor antagonist, significantly attenuated N-PCT-induced reduction in food intake and body weight in a dose-dependent manner. Furthermore, i.c.v. administration of N-PCT increased plasma adrenocorticotrophic hormone and corticosterone concentrations and induced the expression of Fos protein, a marker of neuronal activity, in parvocellular CRF neurones. These data collectively support the hypothesis that N-PCT inhibits food intake and body weight and stimulates the HPA axis via CRF-mediated pathways.

Immune regulation of procalcitonin: a biomarker and mediator of infection

Procalcitonin (PCT) has recently emerged as a powerful biomarker for an early and accurate diagnosis of bacterial infection. Here we summarize our current understanding of the expression pathways of PCT, its potential cellular sources including immune cells, and factors inducing its secretion. Also addressed is the significance of increased blood PCT concentration, which may allow this molecule not only to act as a clinical biomarker but also as an active participant in the development and progression of infectious processes. Experimental approaches to delineate a better understanding of PCT functions, molecular pathways that modulate its expression and therapeutic opportunities to curtail its biological actions are discussed, as well.

The usefulness of procalcitonin and C-reactive protein as early diagnostic markers of bacteremia in cancer patients with febrile neutropenia

Purpose

Procalcitonin (PCT) and C-reactive protein (CRP) are well known inflammatory markers. This study was designed to determine whether PCT and CRP are useful as early diagnostic markers for bacteremia in cancer patients with febrile neutropenia (FN) in the emergency department (ED).

Materials and Methods

In this retrospective study, 286 episodes of FN in the ED were consecutively included between June 2009 and August 2010. From medical records, clinical characteristics including PCT and CRP were extracted and analyzed.

Results

Bacteremia was identified in 38 (13.3%) of the 286 episodes. The median values of PCT (2.8 ng/mL vs. 0.0 ng/mL, p=0.000) and CRP (15.9 mg/dL vs. 5.6 mg/dL, p=0.002) were significantly higher in the group with bacteremia compared to the group without bacteremia. In univariate analysis, elevated PCT (>0.5 ng/mL) and CRP (>10 mg/dL) as well as older age, hypotension, tachycardia, tachypnea, and high body temperature were significantly associated with bacteremia. On multivariate analysis, elevated PCT (>0.5 ng/mL) (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.4 to 9.2; p<0.01) and tachypnea (OR, 3.4; 95% CI, 1.4 to 8.5; p<0.01) were independent early diagnostic markers for bacteremia in FN patients. The area under the curve of PCT was 74.8% (95% CI, 65.1 to 84.6%) and that of CRP was 65.5% (95% CI, 54.8 to 76.1%). With a PCT cut-off value of 0.5 ng/mL, sensitivity and specificity were 60.5% and 82.3%, respectively, while the sensitivity and specificity were 57.6% and 67.3%, respectively, with a CRP cutoff of 10 mg/dL.

Conclusion

These findings suggest that PCT is a useful early diagnostic marker for the detection of bacteremia in FN at the ED and has better diagnostic value than CRP.

The role of procalcitonin for acute pyelonephritis and subsequent renal scarring in infants and young children

PURPOSE

We assessed the usefulness of procalcitonin as a biological marker in diagnosing acute pyelonephritis and for predicting subsequent renal scarring in young children with a first febrile urinary tract infection.

MATERIALS AND METHODS

Children 2 years old or younger with a first febrile urinary tract infection were prospectively studied. Renal parenchymal involvement was assessed by (99m)Tc-dimercaptosuccinic acid scan within 5 days of admission and after 6 months. Serum samples from all patients were tested for procalcitonin, C-reactive protein and white blood cell count measurements.

RESULTS

The 112 enrolled patients (age range 24 days to 24 months old) were divided into acute pyelonephritis (76) and lower urinary tract infection (36) groups according to the results of (99m)Tc-dimercaptosuccinic acid scans. Median values of procalcitonin, C-reactive protein and white blood cell count at hospitalization were significantly higher in patients with acute pyelonephritis than in those with lower urinary tract infection. The area under receiver operating characteristic curves showed that procalcitonin was superior to C-reactive protein and white blood cell count as a marker for diagnosing acute pyelonephritis. Initial and post-antibiotic treatment procalcitonin values were significantly higher in children with renal scarring than in those without scarring (p <0.001). Procalcitonin values at hospitalization and after treatment were independent predictors of later renal scarring on logistic regression analysis.

CONCLUSIONS

Our results indicate the superior diagnostic accuracy of procalcitonin for predicting acute pyelonephritis in children 2 years old or younger. Higher initial and posttreatment procalcitonin values are independent risk factors for later renal scarring.

Comparison of Serum CRP and Procalcitonin in Patients after Spine Surgery

OBJECTIVE

Classical markers of infection cannot differentiate reliably between inflammation and infection after neurosurgery. This study investigated the dynamics of serum procalcitonin (PCT) in patients who had elective spine surgeries without complications.

METHODS

Participants were 103 patients (47 women, 56 men) who underwent elective spinal surgery. Clinical variables relevant to the study included age, sex, medical history, body mass index (BMI), site and type of surgery, and surgery duration. Clinical and laboratory data were body temperature, white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and PCT, all measured preoperatively and postoperatively on days 1, 3, and 5.

RESULTS

PCT concentrations remained at <0.25 ng/mL during the postoperative course except in 2 patients. PCT concentrations did not correlate with age, sex, DM, hypertension, BMI, operation time, operation site, or use of instrumentation. In contrast, CRP concentrations were significantly higher with older age, male, DM, hypertension, longer operation time, cervical operation, and use of instrumentation.

CONCLUSION

PCT may be useful in the diagnosing neurosurgical patients with postoperative fever of unknown origin.

Immunoneutralization of the aminoprocalcitonin peptide of procalcitonin protects rats from lethal endotoxaemia: neuroendocrine and systemic studies

Severe sepsis and septic shock are an important cause of mortality and morbidity. These illnesses can be triggered by the bacterial endotoxin LPS (lipopolysaccharide) and pro-inflammatory cytokines, particularly TNF-α (tumour necrosis factor-α) and IL (interleukin)-1β. Severity and mortality of sepsis have also been associated with high concentrations of N-PCT (aminoprocalcitonin), a 57-amino-acid neuroendocrine peptide derived from ProCT (procalcitonin). Previous studies in a lethal model of porcine polymicrobial sepsis have revealed that immunoneutralization with IgG that is reactive to porcine N-PCT significantly improves short-term survival. To explore further the pathophysiological role of N-PCT in sepsis, we developed an antibody raised against a highly conserved amino acid sequence of human N-PCT [N-PCT-(44-57)]. This sequence differs by only one amino acid from rat N-PCT. First, we demonstrated the specificity of this antibody in a well-proven model of anorexia induced in rats by central administration of human N-PCT-(1-57). Next we explored further the therapeutic potential of anti-N-PCT-(44-57) in a rat model of lethal endotoxaemia and determined how this immunoneutralization affected LPS-induced lethality and cytokine production. We show that this specific antibody inhibited the LPS-induced early release of TNF-α and IL-1β and increased survival, even if treatment began after the cytokine response had occurred. In addition, anti-N-PCT-(44-57) may increase long-term survival in LPS-treated rats by up-regulating the late production of counter-regulatory anti-inflammatory mediators such as ACTH (adrenocorticotropic hormone) and IL-10. In conclusion, these results support N-PCT as a pro-inflammatory factor in both the early and the late stages of lethal endotoxaemia, and suggest anti-N-PCT as a candidate for septic shock therapy.

Procalcitonin as a marker of postoperative complications

OBJECTIVE

Procalcitonin (PCT) is a 116 amino acid peptide that functions as a pro-hormone for calcitonin in the C cells of the thyroid gland. Large quantities of intact PCT are present in the blood of patients with sepsis, particularly when organ dysfunction occurs. PCT has been proposed as an early marker of postoperative complications. The aim of this study was to examine the diagnostic accuracy of PCT as a marker of postoperative complications by systematically reviewing the existing literature.

MATERIAL AND METHODS

The databases PubMed, Embase and the Cochrane Library were searched to find studies on the diagnostic accuracy of PCT in the postoperative phase. Primary studies were retrieved using specific inclusion and exclusion criteria.

RESULTS

A total of nine studies were included. These studies were heterogeneous regarding the spectrum of patients, complications, design and methodological quality according to QUADAS (quality assessment of studies of diagnostic accuracy). This could explain the marked variation in diagnostic accuracy. Considering all types of complications the sensitivity ranged from 37% to 100% and the specificity from 70% to 100%. On examining the infectious complications separately, it was found that the sensitivity ranged from 70% to 86% and the specificity from 45% to 98%.

CONCLUSIONS

Owing to a pronounced heterogeneity among the existing studies, the diagnostic accuracy of PCT as a marker for postoperative complications is not yet sufficiently clarified.

Strong correlation of B2-microglobulin (B2-m) with procalcitonin (PCT) in the serum of chronic hemodialysis patients: a role for infections in the dialysis-related amyloidosis?

INTRODUCTION

Infections trigger the activation of defensive cells capable to produce and release B(2)-microglobulin (B(2)-m). Procalcitonin (PCT), secreted by a wide range of human cells, included the aforementioned defensive cells, is generally considered a sensitive and specific marker of infection. In this prospective study, we examined the possibility that infections, as detected by increased levels of PCT, increase the serum levels of B(2)-m in chronic hemodialysis (CHD) patients, possibly affecting the rate of progression of dialysis-related amyloidosis (DRA).

METHODS

For a period of four months, 76 CHD patients, 45 men/31 women, mean age 63 +/- 15.7 years, with no residual renal function and in HD for 46 +/- 50 months were studied bimonthly. Blood was drawn, at baseline T(0), two months T(2), and four months T(4), for measuring hematocrit (Ht), white blood cells (WBC), erythrocyte sedimentation rate (ESR), blood urea and serum creatinine, protein (albumin, globulin), C-reactive protein (CRP), and PCT kappa alpha iota B(2)-m. Any events (especially infections) in the preceding 10-day period were recorded.

RESULTS

At baseline, 100% of all B(2)-m measurements were abnormal (>2.4 mg/L), 13.4% of PCT values were increased (>1.5 ng/mL), and 49.4% of CRP values exceeded the lower limit of 5 mg/L with no statistically significant differences between the results of the three periods of the study. Statistically significant, in all periods, was the linear positive correlation of B(2)-m with PCT (T[0]: p < 0.001, T[2]: p < 0.004, T[4]: p < 0.001). Also, statistically significant (p < 0.005) was the positive correlation of B(2)-m to HD vintage.

CONCLUSIONS

In this study, the strong positive correlation of B(2)-m to PCT probably signifies that the (mainly subclinical) infections increase B(2)-m production in CHD patients intensifying the problem of HD-related amyloidosis.

Evaluation of serum procalcitonin and interleukin-6 levels as markers of liver metastasis

OBJECTIVES

Procalcitonin (PCT) and interleukin-6 (IL-6) are established markers of tissue inflammation and injury. The aim of the present study was to investigate the possible correlation of PCT and IL-6 with liver metastasis.

DESIGN AND METHODS

The study consisted of fifteen healthy controls (group A), twenty-one patients with solid tumors without metastases (group B), eleven patients with liver metastasis only (group C) and eleven patients with generalized metastatic disease (group D).

RESULTS

Serum PCT levels were significantly increased in group D compared to groups A (p<0.001) and B (p=0.004), but no difference was observed in PCT levels between groups C and B or C and D. IL-6 serum levels were markedly elevated in group C compared to group A (p<0.001) or to groups B (p<0.001) and D (p=0.02). A positive correlation was observed between PCT and IL-6 serum levels (r=0.357, p=0.019).

CONCLUSIONS

PCT levels are related to disease stage in cancer patients, whereas IL-6 concentration seems to be a more specific marker of liver metastasis.

Procalcitonin, lipopolysaccharide-binding protein, interleukin-6 and C-reactive protein in community-acquired infections and sepsis: a prospective study

INTRODUCTION

Clinicians are in need of better diagnostic markers in diagnosing infections and sepsis. We studied the ability of procalcitonin, lipopolysaccharide-binding protein, IL-6 and C-reactive protein to identify patients with infection and sepsis.

METHODS

Plasma and serum samples were obtained on admission from patients with suspected community-acquired infections and sepsis. Procalcitonin was measured with a time-resolved amplified cryptate emission technology assay. Lipopolysaccharide-binding protein and IL-6 were measured with a chemiluminescent immunometric assay.

RESULTS

Of 194 included patients, 106 had either infection without systemic inflammatory response syndrome or sepsis. Infected patients had significantly elevated levels of procalcitonin, lipopolysaccharide-binding protein, C-reactive protein and IL-6 compared with noninfected patients (P < 0.001). In a receiver-operating characteristic curve analysis, C-reactive protein and IL-6 performed best in distinguishing between noninfected and infected patients, with an area under the curve larger than 0.82 (P < 0.05). IL-6, lipopolysaccharide-binding protein and C-reactive protein performed best in distinguishing between systemic inflammatory response syndrome and sepsis, with an area under the curve larger than 0.84 (P < 0.01). Procalcitonin performed best in distinguishing between sepsis and severe sepsis, with an area under the curve of 0.74 (P < 0.01).

CONCLUSION

C-reactive protein, IL-6 and lipopolysaccharide-binding protein appear to be superior to procalcitonin as diagnostic markers for infection and sepsis in patients admitted to a Department of Internal Medicine. Procalcitonin appears to be superior as a severity marker.

Identification and localization of procalcitonin-like immunoreactivity in the rat hypothalamus

Procalcitonin (PCT) is a 116-amino acid polypeptide physiologically produced, as the precursor protein of calcitonin (CT), in the parafollicular cells of the thyroid gland, but physiological functions and other major sources of PCT remains unclear. The distribution of PCT-like immunoreactivity (PCT-LI) in the rat hypothalamus was examined by immunohistochemistry using a monoclonal antibody raised against the mid-region of human PCT (60-77-amino acid fragment). This antibody cross-reacts well with rat PCT and immature CT, but it cross-react poorly with free mature CT. Abundant expression of PCT-LI was found in zones at the interface between brain and cerebrospinal fluid (CSF) such as the ependymal layer and ventral glia limitans (VGL). Double labeling of PCT and glial fibrillary acidic protein (GFAP) identified this population of small cells as astrocytes, possibly tanycytes, a type of specialized glial cell that interacts in neuroendocrine functional dynamics. The fibers of these cells extend to circumventricular organs (CVOs) and to astrocytes located inside the parenchyma of key autonomic regulatory hypothalamic areas, with highest densities in the supraoptic nucleus (SO), arcuate nucleus (Arc), area postrema (AP), median eminence (ME), medial preoptic nucleus, tuber cinereum, and accessory neurosecretory nuclei. No strongly labeled cells were found in the paraventricular nucleus. The wide distribution of PCT-LI in the hypothalamus, in close correspondence with previous mapping of CT receptors in the rat brain, suggests that PCT may influence a multitude of biological activities associated with the hypothalamic-pituitary axis.

Multicenter prospective study of procalcitonin as an indicator of sepsis

The clinical significance of serum procalcitonin (PCT) for discriminating between bacterial infectious disease and nonbacterial infectious disease (such as systemic inflammatory response syndrome (SIRS)), was compared with the significance of endotoxin, beta-D: -glucan, interleukin (IL)-6, and C-reactive protein (CRP) in a multicenter prospective study. The concentrations of PCT in patients with systemic bacterial infection and those with localized bacterial infection were significantly higher than the concentrations in patients with nonbacterial infection or noninfectious diseases. In addition, PCT, endotoxin, IL-6, and CRP concentrations were significantly higher in patients with bacterial infectious disease than in those with nonbacterial infectious disease (P<0.001, P<0.005, P<0.001, and P<0.001, respectively). The cutoff value of PCT for the discrimination of bacterial and nonbacterial infectious diseases was determined to be 0.5 ng/ml, which was associated with a sensitivity of 64.4% and specificity of 86.0%. Areas under the receiver operating characteristic curves (POCs) were 0.84 for PCT, 0.60 for endotoxin, 0.77 for IL-6, and 0.78 for CRP in the combined group of patients with bacterial infectious disease and those with nonbacterial infectious disease, and the area under the ROC for PCT was significantly higher than that for endotoxin (P<0.001). In patients diagnosed with bacteremia based on clinical findings, the positive rate of diagnosis with PCT was 70.2%, while that of blood culture was 42.6%. PCT is thus essential for discriminating bacterial infection from SIRS, and is superior in this respect to conventional serum markers and blood culture.

Procalcitonin levels in plasma in oncohaematologic patients with and without bacterial infections

BACKGROUND

The flogosis markers currently in use show both low sensitivity and specificity, particularly in neoplastic and degenerative diseases. Procalcitonin (PCT) is a pro-peptide of calcitonin produced mainly but not only in the C-cells of the thyroid glands and, as several studies show, PCT levels in plasma increase during infections. Bacterial infections are also the main cause of death in oncological patients. Furthermore, in patients with leukaemia in chemotherapy recovery, infections often induce relapses. The aim of the present study is to detect PCT levels in plasma in oncohaematologic patients with and without infections.

METHODS

The study was carried out on 54 patients by a quantitative automated immunoassay.

RESULTS

PCT plasma levels > or =0.5 ng were detected in 27 out of 30 patients (90,0%) with bacterial infections; 8 out of 9 patients (88,9%) with viral infections and in 12 out of 15 patients in the control group without statistically significant differences.

CONCLUSIONS

The results, which differ from those in the literature, are discussed.

Assessment of procalcitonin as a diagnostic and prognostic marker in patients with solid tumors and febrile neutropenia

BACKGROUND

Cancer patients with fever and neutropenia currently are assessed on clinical grounds only. The current study prospectively evaluated the efficacy of baseline procalcitonin (PCT) in the detection of bacteremia and in the prediction of outcome in patients with solid tumors and febrile neutropenia.

METHODS

PCT levels were determined at baseline and every 48 hours in 104 patients undergoing chemotherapy who developed fever (axillary temperature > 38 degrees C on 2 occasions or > 38.3 degrees C in a single record) and neutropenia (absolute neutrophil count < 500 cells/microL).

RESULTS

The median baseline PCT values were significantly higher in patients who had microbiologically documented infections (1.24 ng/mL) compared with patients who had clinically documented infections (0.27 ng/mL) or fever of unknown origin (0.21 ng/mL; P < 0.01). Accordingly, a PCT cut-off value of 0.5 ng/mL was reached more frequently in patients who had microbiologically documented infections compared with patients who had clinically documented infections or fever of unknown origin (66.7% vs. 13.4%, respectively; P < 0.001). Furthermore, this threshold also was associated with an increased likelihood of treatment failure (70.0% vs. 14.9%; P < 0.001). All 4 septic patients and all 5 patients who ultimately died presented PCT values 5-fold to 10-fold greater than the median values. Clinical evaluation in combination with baseline PCT assessment appeared to improve clinical risk evaluation alone.

CONCLUSIONS

Baseline PCT levels were higher in patients who had febrile neutropenia with bacteremia compared with patients who had clinical infections or fever of unknown origin. PCT helped to identify patients who had microbiologic infections and patients who were at high risk of treatment failure, and PCT may constitute a complementary tool in the initial assessment of such patients.

Expression and localization of prohormone convertase PC1 in the calcitonin-producing cells of the bullfrog ultimobranchial gland

We examined the expression and localization of the prohormone convertases, PC1 and PC2, in the ultimobranchial gland of the adult bullfrog using immunohistochemical (IHC) and in situ hybridization (ISH) techniques. In the ultimobranchial gland, PC1-immunoreactive cells were columnar, and were present in the follicular epithelium. When serial sections were immunostained with anti-calcitonin, anti-CGRP, anti-PC1, and anti-PC2 sera, PC1 was found only in the calcitonin/CGRP-producing cells. No PC2-immunopositive cells were detected. In the ISH, PC1 mRNA-positive cells were detected in the follicle cells in the ultimobranchial gland. No PC2 mRNA-positive cells were detected. RT-PCR revealed expression of the mRNAs of PC1 and the PC2 in the ultimobranchial gland. However, very little of the PC2 mRNA is probably translated because no PC2 protein was detected either by IHC staining or by Western blotting analysis. We conclude that the main prohormone convertase that is involved in the proteolytic cleavage of procalcitonin in the bullfrog is PC1.

CTLA-4 positive T cells in contrast to procalcitonin plasma levels discriminate between severe and uncomplicated Plasmodium falciparum malaria in Ghanaian children

Procalcitonin (PCT) plasma levels and the fraction of CTLA-4-positive T cells are both elevated in acute Plasmodium falciparum malaria in human adults and the degree of elevation is positively correlated with other markers of disease severity, for example with parasitaemia. However, the clinical manifestations of malaria are strongly age-dependent and children from endemic areas carry the main disease burden. Therefore, we measured PCT plasma levels and CTLA-4 expression by T cells in four groups of children from the Ashanti Region in Ghana: asymptomatic children with or without parasitaemia, children with uncomplicated P. falciparum malaria and children with severe disease. PCT levels were highly elevated in both groups with acute malaria but they did not discriminate between uncomplicated and severe disease. In contrast, CTLA-4-expression by T cells was increased only in severe malaria. The fraction of CTLA-4 positive T cells in the blood of children with severe disease differed significantly from that in uncomplicated malaria, which was not elevated in spite of the high parasite loads observed in these children. This was unexpected, as in adults uncomplicated malaria is associated with a dramatic sixfold increase of the fraction of CTLA-4-positive T cells. The data from this study support the hypothesis that strong T cell activation as measured here by CTLA-4 expression is not just the by-product of a high parasite burden, but that it contributes to the pathogenesis of P. falciparum malaria.

Plasma Levels of Procalcitonin and Neopterin in Multiple Trauma Patients with or without Brain Injury

Clinical and experimental evidence suggests that traumatic brain injury (TBI) leads to a systemic immune response. To examine whether TBI causes a release of procalcitonin (PCT) or neopterin (NT) into the circulation, we compared plasmatic mediator levels among multiple injured patients with or without TBI. In total, 98 trauma patients (24 with TBI only, 39 with extracranial injuries excluding TBI, and 35 with combined injuries) and 35 healthy volunteers were studied. Blood was sampled at 15 predefined time points within 132 h after injury and analysed for NT and PCT. Multivariate statistical comparisons were adjusted for different severity of head, thorax, abdomen and extremity injuries, as quantified by the Abbreviated Injury Scale (AIS). PCT was normal 3 h after trauma, but 24 h after extracranial injuries a massive release (median 3 ng/mL) was observed. Significant positive associations between injury severity and posttraumatic PCT levels were found for abdominal and extremity, but not for cranial or thoracic injuries. Only modest changes of marginal statistical significance were detected for NT. The maximum increase per AIS point was 9% (95% confidence intervals [CI]: 3-16%). The effect of TBI on NT release was significant only at 108 h posttrauma with a 5% (95% CI: 1-10%) increase per AIS point. TBI induces a release of PCT and NT into the plasma, but this effect seems to be smaller for intra- than for extracranial injuries, probably due to more extensive surgery for abdominal and extremity injuries.

Calcitonin gene related peptide and N-procalcitonin modulate CD11b upregulation in lipopolysaccharide activated monocytes and neutrophils

OBJECTIVE

Circulating levels of calcitonin gene related peptide (CGRP) and calcitonin precursors, including procalcitonin (PCT) and its free aminopeptide N-procalcitonin (N-PCT), have been found dramatically increased in septic patients. PCT is known to attenuate the chemotaxis of monocytes in response to chemoattractants. This study examined whether CGRP and N-PCT modulate the LPS-induced expression of CD11b, which is one of the major integrins involved in monocyte and neutrophil chemotaxis during a response to microbial infections.

DESIGN AND SETTING

In vitro cell culture study in the immunology laboratory of a university hospital.

PARTICIPANTS

Healthy volunteers.

MEASUREMENTS AND RESULTS

We assessed the effects of N-PCT and CGRP on CD11b expression on monocytes and neutrophils after LPS (2 ng/ml) or fMLP (10(-8) M) challenges. We used a human whole blood model, and measurements were made by flow cytometry. Both peptides in a dose-dependent manner decreased the LPS- and fMLP-induced rise in CD11b in monocytes and neutrophils. As these peptides are thought to act by raising cAMP, we also mimicked their effects with the use of rolipram and forskolin and found similar results.

CONCLUSIONS

These findings are in line with recent studies demonstrating anti-inflammatory properties for this family of peptides. CGRP and calcitonin precursors may function as factors suppressing the propagation of inflammation through the inhibition of several processes involved during a response to a bacterial stimulus.

Elevated serum procalcitonin values correlate with renal scarring in children with urinary tract infection

BACKGROUND

Urinary tract infection (UTI) in young children carries the risk of parenchymal damage and sequelae. The location of the infection within the urinary tract influences decisions regarding both therapeutics and follow-up. Because clinical features and laboratory markers of infection at an early age are not specific, it is difficult to make a distinction between lower UTI and acute pyelonephritis. Procalcitonin (PCT) has been studied as a marker of severe bacterial infection. The aim of this study was to test the usefulness of PCT concentration in serum to distinguish between uncomplicated UTI and severe acute pyelonephritis with renal scars.

METHODS

PCT was measured by immunoluminometric assay in serum samples from children with microbiologically documented infection. Severe renal involvement was assessed by 99mTc-dimercaptosuccinic acid gammagraphy done 5 to 6 months after the episode to check for the presence of parenchymal scars. C-reactive protein (CRP) and leukocyte count were also measured.

RESULTS

PCT at presentation showed a significant correlation (P < 0.001) with the presence of renal scars in children with UTI. Using a cutoff of 1 ng/ml for PCT and 20 mg/l for CRP, sensitivity and specificity in distinguishing between urinary tract infection with and without renal damage were 92.3 and 61.9%, respectively, for PCT and 92.3 and 34.4% for CRP. Positive and negative predictive values were 32 and 97.5%, respectively, for PCT and 23 and 95%, respectively, for CRP.

CONCLUSIONS

A low PCT value at admission indicates a low risk of long term renal scarring. Increased PCT values at admission correlate with the presence of scars. PCT values have proved to be more specific than CRP and leukocyte count for identifying patients who might develop renal damage.

Procalciton: A new marker and mediator of systemic inflammatory response of the host to infection

<zakljucak> Prokalcitonin je medijator generalizovane reakcije domacina na infekciju, koji poseduje znacajan imunomodulatorni efekat. Indukcija PCT i porast njegovog nivoa u plazmi povezani su sa ekstenzivnoscu i tipom sistemske inflamacije, a njegova koncentracija se naglo smanjuje posle saniranja inflamacije. Kod bolesnika sa sepsom PCT je odlican dijagnosticki i prognosticki marker i veoma dobar parametar za procenu uspeha terapijskog tretmana i klinickog toka septickog procesa. Rutinsko odredjivanje njegove koncentracije u krvi moze popraviti laboratorijsko pracenje bolesnika sa sepsom.

Pathobiochemistry and clinical use of procalcitonin

Induction of the protein procalcitonin during infection and inflammation was first described approximately 10 years ago. A large number of publications, primarily clinical studies, demonstrate the increasing use of procalcitonin in modern clinical practice. However, data on the biological function and origin of procalcitonin is scarce. Findings regarding the possible role and source of procalcitonin in sepsis and infection were recently published, and the pathophysiology of the protein has meanwhile been investigated in various experimental models. Procalcitonin obviously has certain biological functions, and it is also known to be specifically induced. Given the hormonal origin of the mature protein and the inflammation-related functions of its propeptides, some investigators suggest that procalcitonin should be referred to as a "hormokine," although its biological functions should be studied in more detail. This review will survey the data now available in recent publications on the induction, production sources, possible biological functions and clinical uses of procalcitonin.

Immunocytochemical localization of prohormone convertases PC1 and PC2 in the mouse thyroid gland and respiratory tract

We examined immunocytochemical localization of the prohormone convertases, PC1 and PC2, in the thyroid gland and respiratory tract of the adult mouse using the indirect enzyme- and immunogold-labeled antibody methods for light and electron microscopy, respectively. In the thyroid gland, PC1- and/or PC2-immunoreactive cells were cuboidal, scattered in the follicular epithelium and in the interfollicular spaces. When serial sections were immunostained with anti-calcitonin, anti-PC1, anti-calcitonin-gene-related-peptide (CGRP), and anti-PC2 sera, respectively, localization of both PC1 and PC2 was restricted to the calcitonin/CGRP-producing parafollicular cells. In the respiratory tract, only PC1 immunoreactivity was observed in the basal granulated neuroendocrine cells, which were scattered in the tracheal epithelium. Consecutive sections immunostained with anti-PC1 and anti-CGRP sera showed that a subpopulation of these PC1-immunoreactive cells contained CGRP. Double immunogold electron microscopy of the thyroid parafollicular cells revealed that calcitonin- and/or CGRP-immunopositive secretory granules were also labeled with both PC1 and PC2. These findings suggest that procalcitonin is proteolytically cleaved by PC2 alone or by PC2 together with PC1, and that the proCGRP is cleaved by PC1.

Procalcitonin following elective partial liver resection--origin from the liver?

BACKGROUND

The origin of the inflammatory peptide procalcitonin (PCT) is still unknown. In the present study PCT concentrations in arterial and hepatic-venous blood were examined in patients undergoing elective partial liver resection (LR) using a fiberoptic pulmonary arterial catheter placed in a liver vein to obtain further information on the origin of PCT.

METHODS

In 28 patients (21 male/7 female; average age of 58.8+/-8.8 years) undergoing LR, arterial and hepatic venous PCT concentrations were measured during 24 h perioperatively. The parallel blood withdrawals occurred immediately before the Pringle maneuver (Hx), 2 min, 1, 2, 6, 12, and 24 h after Hx. Over the whole period, the oxygen saturation in hepatic venous blood (ShvO2) was monitored. PCT concentrations were assayed by immunoluminometry.

RESULTS

We observed a significant increase in PCT concentration already 6 h after Hx compared to the values before Hx. Twenty-four hours after Hx we found the highest plasma concentrations. It was conspicuous that hepatic venous PCT concentrations were always higher than the arterial ones (significantly from the 6th hour after Hx). There was no correlation between the courses of ShvO2 and PCT rise. A significant correlation was verified between Hx duration and PCT concentration measured 24 h after Hx both in the hepatic venous and arterial blood.

CONCLUSIONS

The results of our investigation can be interpreted as evidence that liver (or the hepatosplanchnicus?) is a source of PCT. The mechanism of PCT induction cannot be clarified by our study: whether the induction of PCT was caused by an endotoxin translocation during the impeded splanchnic outflow or by the direct surgery-induced lesion (hypoxia) of the liver remains unclear. However, the latter appears more probable because of the observed correlation between Hx duration and PCT concentration rise.

Clinical evaluation of a new sensitive calcitonin assay: study of specificity

BACKGROUND

Calcitonin (CT) is the most sensitive marker available for medullary thyroid carcinoma, but it lacks specificity. Procalcitonin is the precursor protein of calcitonin. Infections are known to be associated with elevations of procalcitonin. The aim of this study was to evaluate a new sensitive calcitonin assay in a large population and to study the assay specificity in two particular populations: patients with renal failure and patients hospitalized in intensive care units with a high procalcitonin level.

METHODS

Using two immunometric assays (A and B) to detect only mature calcitonin, we evaluated the calcitonin level in 488 sera (46 stimulation tests) from 340 subjects.

RESULTS

The clinical evaluation showed that the calcitonin concentrations obtained with the two assays were similar for all patients except those with high procalcitonin levels. Among the patients, 12% (n=13) had basal calcitonin concentrations greater than 10 pg/ml with method A and 25.7% (n=25) with kit B. No correlation was found between calcitonin and procalcitonin concentrations.

CONCLUSION

The new sensitive calcitonin assay tested is very efficient especially for the low concentrations. The cross-reaction for high procalcitonin levels exists and is variable according to the kits used. The procalcitonin evaluation can help the interpretation of ambiguous calcitonin levels.

Procalcitonin as an acute phase marker

Procalcitonin is a 14-kDa protein encoded by the Calc-1 gene along with calcitonin and katacalcin. The function and regulation of this protein are quite different from those of the other gene products. Blood concentrations of procalcitonin are increased in systemic inflammation, especially when this is caused by bacterial infection. Studies of its behaviour in patients with bacterial sepsis have led to the proposal that it may be a useful marker of systemic bacterial infection, with greater specificity and sensitivity than acute phase proteins such as C-reactive protein.

Usefulness of procalcitonin and C-reactive protein rapid tests for the management of children with urinary tract infection

BACKGROUND

Urinary tract infection (UTI) is a common problem in children. Because clinical findings and commonly used blood indices are nonspecific, the distinction between lower and upper urinary tract infection cannot be made easily in this population. However, this distinction is important because renal infection can induce parenchymal scarring. The objective of this study was to determine the accuracy of procalcitonin (PCT) compared with C-reactive protein (CRP) rapid tests to predict renal involvement in children with febrile UTI.

METHODS

PCT and CRP were measured in the blood of children admitted to the emergency room with fever, signs and symptoms of urinary tract infection and/or a positive urine dipstick analysis. Renal parenchymal involvement was assessed by a 99mTc-labeled dimercaptosuccinic acid renal scan in the acute phase of infection in all children. Sensitivity, specificity and likelihood ratios were determined for both tests.

RESULTS

Fifty-four children with a proven urinary tract infection were enrolled: 63% had renal involvement; and 37% had infection restricted to the lower urinary tract. No difference was found for age, sex and total white blood cell count between the groups. The calculated likelihood ratios of procalcitonin and C-reactive protein rapid tests were between 3.8 and 7 and 1.5 and 2.8, respectively. A positive PCT value predicted renal involvement in 87 to 92% of children with febrile UTI, compared with 44 to 83% using CRP values.

CONCLUSIONS

A rapid determination of procalcitonin concentration could be useful for the management of children with febrile UTI in the emergency room.