Y12 nitration of human calcitonin (hCT): A promising strategy to produce non-aggregation bioactive hCT.

Irreversible aggregation can extremely limit the bioavailability and therapeutic activity of peptide-based drugs. There is therefore an urgent demand of effective strategy to control peptide aggregation. Recently, we found that tyrosine nitration at certain sites of peptide can effectively inhibit its aggregation. This minor modification may be an ideal strategy to the rational design of peptide-based drugs with low aggregation propensity yet without loss of bioactivity. Human calcitonin (hCT) is such a peptide hormone known for its hypocalcaemic effect but has limited pharmaceutical potential due to a high tendency to aggregate. In this study, by using multiple techniques including Fluorescence, TEM, Nu-PAGE and CD, we demonstrated that Y12 nitration of hCT would significantly inhibit its self-assembles, and we also found that this modification would not only reduce the cytotoxicity induced by peptide aggregation, but also had little effect on its potency. This finding may provide a novel strategy for clinically application of hCT instead of sCT.

Procalcitonin for selecting the antibiotic regimen in outpatients with low-risk community-acquired pneumonia using a rapid point-of-care testing: A single-arm clinical trial.

OBJECTIVE: We aimed to assess the role of procalcitonin (PCT) to guide the initial selection of the antibiotic regimen for low-risk community-acquired pneumonia (CAP). METHODS: A single-arm clinical trial was conducted including outpatients with CAP and Pneumonia Severity Index risk classes I-II. Antimicrobial selection was based on the results of PCT measured with a rapid point-of-care testing. According to serum PCT levels, patients were assigned to two treatment strategies: oral azithromycin if PCT was <0.5 ng/ml, or levofloxacin if levels were ≥0.5 ng/ml. Primary outcome was clinical cure rate. Short-term and long-term outcomes were assessed. Results were compared with those of a historical standard-of-care control-group treated in our centre. RESULTS: Of 253 subjects included, 216 (85.4%) were assigned to azithromycin. Pneumococcal infection was diagnosed in 26 (12%) and 21 (56.8%) patients allocated to azithromycin and levofloxacin groups, respectively. No patients in the azithromycin group developed bacteraemia. Atypical organisms were more common in patients given azithromycin (18.5% vs 8.1%, respectively). The majority (93%) of patients with atypical pneumonia had low PCT levels. Clinical cure rates were 95.8% in the azithromycin group, 94.6% in the levofloxacin group, and 94.4% in the historical control group. No 30-day mortality or recurrences were observed, and the 3-year rates of recurrence and mortality were very low in both groups. Adverse events occurrence was also infrequent. CONCLUSION: A PCT-guided strategy with a rapid point-of-care testing safely allowed selecting empirical narrow-spectrum antibiotics in outpatients with CAP. TRIAL REGISTRATION: The study is registered with ClinicalTrials.gov, number NCT02600806.

Kinetics of plasma procalcitonin, soluble CD14, CCL2 and IL-10 after a sublethal infusion of lipopolysaccharide in horses.

Endotoxemia represents a significant clinical and economic problem for the equine industry. This study assesses the kinetics of soluble CD14 (sCD14), chemokine (CC motif) ligand 2 (CCL2), interleukin 10 (IL-10) and plasma procalcitonin (PCT) in healthy horses after the intravenous infusion of lipopolysaccharide (LPS). The aim was to contribute to the basic understanding of the equine species-specific kinetics of these molecules in response to LPS exposure, which could support further findings in clinical studies and identify valuable inflammatory biomarkers for equine practice. Eleven healthy horses were involved in this experimental in vivo study. Horses were classified as healthy before the LPS infusion. After the pre-infusion blood collection (T0), all horses received an infusion of E. coli endotoxin (30ng/kg over 30min). Data and samples were collected 1h (T1), 2 (T2), 3 (T3) and 24h (T24) after infusion. Plasma sCD14, CCL2 and IL-10 were evaluated with a fluorescent bead-based assay, while PCT was evaluated with an equine PCT ELISA assay. A one-way ANOVA test was performed between each blood-sampling time for PCT, sCD14 and IL-10, and a Friedman test was performed for CCL2. Plasma PCT, IL-10 and CCL2 concentrations increased statistically significantly at T1, T2 and T3 compared to T0. No statistically significant differences were found between plasma IL-10 and CCL2 concentrations between T0 vs T24, although plasma PCT values remained high 24h after LPS infusion. Plasma sCD14 concentration showed no statistically significant differences for any of sampling times. Our results demonstrate that LPS injection into healthy horses results in PCT, CCL2 and IL-10 increases in plasma without an increase in sCD14. The increases in PCT, CCL2 and IL-10 are related to the inflammatory response induced by circulating lipopolysaccharide.

Glucagon-like peptide-1(GLP-1) receptor agonists: potential to reduce fracture risk in diabetic patients?

This review summarizes current knowledge about glucagon-like peptide 1 receptor agonists (GLP-1 RA) and their effects on bone metabolism and fracture risk. Recent in vivo and in vitro experiments indicated that GLP-1 RA could improve bone metabolism. GLP-1 could affect the fat-bone axis by promoting osteogenic differentiation and inhibiting adipogenic differentiation of bone mesenchymal precursor cells (BMSCs), which express the GLP-1 receptor. GLP-1 RA may also influence the balance between osteoclasts and osteoblasts, thus leading to more bone formation and less bone resorption. Wnt/ß-catenin signalling is involved in this process. Mature osteocytes, which also express the GLP-1 receptor, produce sclerostin which inhibits Wnt/ß-catenin signalling by binding to low density lipoprotein receptor-related protein (LRP) 5 and preventing the binding of Wnt. GLP-1 RA also decreases the expression of sclerostin (SOST) and circulating levels of SOST. In addition, GLP-1 receptors are expressed in thyroid C cells, where GLP-1 induces calcitonin release and thus indirectly inhibits bone resorption. Furthermore, GLP-1 RA influences the osteoprotegerin(OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK) system by increasing OPG gene expression, and thus reverses the decreased bone mass in rats models. However, a recent meta-analysis and a cohort study did not show a significant relationship between GLP-RA use and fracture risk. Future clinical trials will be necessary to investigate thoroughly the relationship between GLP-1 RA use and fracture risk in diabetic patients.

A-kinase anchoring protein 2 is required for calcitonin-mediated invasion of cancer cells.

Expression of neuropeptide calcitonin (CT) and its receptor (CTR) is frequently elevated in prostate cancers (PCs) and activation of CT-CTR axis in non-invasive PC cells induces an invasive phenotype. Specific, cell-permeable inhibitors of protein kinase A abolish CTR-stimulated invasion of PC cells. Since PKA is ubiquitously distributed in cells, the present study examined the mechanism(s) by which CTR-stimulated PKA activity is regulated in time and space. CT reduced cell adhesion but increased invasion of PC cells. Both these actions were abolished by st-Ht31 inhibitory peptide suggesting the involvement of an A-kinase anchoring protein (AKAP) in CT action. Next, we identified the AKAP associated with CT action by the subtraction of potential AKAP candidates using siRNAs. Knock-down of membrane-associated AKAP2, but not other AKAPs, abolished CT-stimulated invasion. Stable knock-down of AKAP2 in PC3-CTR cells remarkably decreased their cell proliferation, invasion, clonogenicity and ability to form orthotopic tumors and distant metastases in nude mice. Re-expression of AKAP2-wt restored these characteristics. Primary PC specimens displayed remarkable upregulation of CTR/AKAP2 expression as compared to benign prostates. Metastatic cancers displayed significantly higher CTR/AKAP2 expression than localized cancers. These results for the first time demonstrate that AKAP2 is expressed in human prostates, its expression is elevated in metastatic prostate cancer, and the knock-down of its expression remarkably decreased tumorigenicity and metastatic ability of prostate cancer cells. AKAP2 may serve as a critical component of CTR-mediated oncogenic actions.

Role of Procalcitonin and Interleukin-6 in Predicting Cancer, and Its Progression Independent of Infection.

Procalcitonin (PCT) and Interleukin-6 (IL-6) have emerged as biomarkers for different inflammatory conditions. The purpose of the study was to evaluate the role of PCT and IL-6 as biomarkers of cancer and its progression in a large cohort of patients. This cross-sectional study included residual plasma samples collected from cancer patients, and control subjects without cancer. Levels of PCT and IL-6 were determined by Kryptor compact bioanalyzer. We identified 575 febrile cancer patients, 410 non-febrile cancer patients, and 79 non-cancer individuals. The median PCT level was lower in control subjects (0.029 ng/ml) compared to cancer patients with stage I-III disease (0.127 ng/ml) (p<0.0001) and stage IV disease (0.190 ng/ml) (p<0.0001). It was also higher in febrile cancer patients (0.310 ng/ml) compared to non-febrile cancer patients (0.1 ng/ml) (p<0.0001). Median IL-6 level was significantly lower in the control group (0 pg/ml) than in non-febrile cancer patients with stages I-III (7.376 pg/ml) or stage IV (9.635 pg/ml) (p<0.0001). Our results suggest a potential role for PCT and IL-6 in predicting cancer in non-febrile patients. In addition, PCT is useful in detecting progression of cancer and predicting bacteremia or sepsis in febrile cancer patients.

Amygdala pain mechanisms.

A limbic brain area, the amygdala plays a key role in emotional responses and affective states and disorders such as learned fear, anxiety, and depression. The amygdala has also emerged as an important brain center for the emotional-affective dimension of pain and for pain modulation. Hyperactivity in the laterocapsular division of the central nucleus of the amygdala (CeLC, also termed the "nociceptive amygdala") accounts for pain-related emotional responses and anxiety-like behavior. Abnormally enhanced output from the CeLC is the consequence of an imbalance between excitatory and inhibitory mechanisms. Impaired inhibitory control mediated by a cluster of GABAergic interneurons in the intercalated cell masses (ITC) allows the development of glutamate- and neuropeptide-driven synaptic plasticity of excitatory inputs from the brainstem (parabrachial area) and from the lateral-basolateral amygdala network (LA-BLA, site of integration of polymodal sensory information). BLA hyperactivity also generates abnormally enhanced feedforward inhibition of principal cells in the medial prefrontal cortex (mPFC), a limbic cortical area that is strongly interconnected with the amygdala. Pain-related mPFC deactivation results in cognitive deficits and failure to engage cortically driven ITC-mediated inhibitory control of amygdala processing. Impaired cortical control allows the uncontrolled persistence of amygdala pain mechanisms.

Structure-activity relationships of two Rhodnius prolixus calcitonin-like diuretic hormone analogs.

The calcitonin-like diuretic hormone (CT/DH) in Rhodnius prolixus influences various tissues associated with feeding-related physiological events. The receptors for this peptide have also been identified and shown to be expressed in these tissues. In the present study, we have investigated the effects of two R. prolixus CT/DH analogs (full-length form and N-terminal truncated form) on hindgut contractions and in a heterologous receptor expression system. The analogs contained the amino acid methyl-homoserine in place of methionine in order to prevent them from being oxidized and thus increase their stability. The full-length form of the analog retained all of its activity in our assays when compared to the endogenous peptide. Truncated analog displayed no activity in our assays.

[Procalcitonin as a marker of intra-abdominal infection]. / La procalcitonina como marcador de infección intraabdominal.

BACKGROUND: Procalcitonin is a quite specific biomarker of infection and in recent years has shown its superiority to others markers of inflammation, such as C-reactive protein, for the diagnosis and monitoring of a variety of infections. AIM: For this reason, several researchers have studied the potential role of procalcitonin for diagnosis and management of these infections. DISCUSSION: Intra-abdominal infections are a heterogeneous group of infections that, sometimes, pose difficult challenges to physicians. The published studies have produced mixed results, leading to controversy on the utility of this marker in intra-abdominal infections. CONCLUSIONS: This review summarizes these data and discuss the utility of procalcitonin in several intra abdominal infections, including postoperative infections.

Antecedentes: la procalcitonina es un marcador bastante específico de infección y en los últimos años se ha demostrado su superioridad, con respecto a otros marcadores de inflamación como la proteína C reactiva, para el diagnóstico y vigilancia de una gran variedad de infecciones. Objetivo: resumir los datos actualmente existentes y discutir la utilidad de la procalcitonina en diversas infecciones intrabdominales, incluidas las postoperatorias. Conclusiones: los resultados de estudios hasta ahora publicados son variables, lo que genera controversia en relación con su utilidad.

The role of the area postrema in the anorectic effects of amylin and salmon calcitonin: behavioral and neuronal phenotyping.

Amylin reduces meal size by activating noradrenergic neurons in the area postrema (AP). Neurons in the AP also mediate the eating-inhibitory effects of salmon calcitonin (sCT), a potent amylin agonist, but the phenotypes of the neurons mediating its effect are unknown. Here we investigated whether sCT activates similar neuronal populations to amylin, and if its anorectic properties also depend on AP function. Male rats underwent AP lesion (APX) or sham surgery. Meal patterns were analysed under ad libitum and post-deprivation conditions. The importance of the AP in mediating the anorectic action of sCT was examined in feeding experiments of dose-response effects of sCT in APX vs. sham rats. The effect of sCT to induce Fos expression was compared between surgery groups, and relative to amylin. The phenotype of Fos-expressing neurons in the brainstem was examined by testing for the co-expression of dopamine beta hydroxylase (DBH) or tryptophan hydroxylase (TPH). By measuring the apposition of vesicular glutamate transporter-2 (VGLUT2)-positive boutons, potential glutamatergic input to amylin- and sCT-activated AP neurons was compared. Similar to amylin, an intact AP was necessary for sCT to reduce eating. Further, co-expression between Fos activation and DBH after amylin or sCT did not differ markedly, while co-localization of Fos and TPH was minor. Approximately 95% of neurons expressing Fos and DBH after amylin or sCT treatment were closely apposed to VGLUT2-positive boutons. Our study suggests that the hindbrain pathways engaged by amylin and sCT share many similarities, including the mediation by AP neurons.

C and APUD cells and endocrine tumours. Pearse's laboratory in the years 1965-1969: a personal recollection.

This paper is a personal recollection of the studies, conducted in Prof. Pearse's laboratory in London in the years 1965-1969, which led to the discovery of production of calcitonin by parafollicular C cells and medullary carcinomas of the thyroid. The author's intention is to underline the combination of technical excellence, brilliant intuition, dedication and serendipity which led to a series of major discoveries and, historically, established the pivotal role to be played by immunohistochemistry in endocrine research and diagnosis. The formulation of Pearse's APUD cell theory gave a formal credence to the existence of common endocrine mechanisms, molecular markers and structural features in dispersed cells, all belonging to a diffuse endocrine system. This represented a major breakthrough which primed, in the following years, the studies on polypeptide hormone-producing cells and tumours, thus paving the way to the endocrine histology and pathology as we know, and practice them today.

Usefulness of procalcitonin in elderly patients with bacterial infection.

BACKGROUND: The role of PCT (procalcitonin) in elderly patients with bacterial infection has not fully been investigated. In previous studies, the role of PCT in diagnosing bacterial infection has mainly been studied in patients with severe infections. This study was to access a diagnostic value of PCT in elderly patients with local infection. METHODS: A total of 259 elderly patients were enrolled in this study. Serum concentration of PCT and whole blood concentration of CRP was measured by immunofluorescence assay. RESULTS: The concentration of PCT was significantly higher in patients with infection than those without. In predicting bacterial infection, with a PCT cutoff value of 0.055 ng/mL, the specificity and sensitivity were 92.4% and 63.6%, respectively, while the specificity and sensitivity was 80.0% and 81.3% with a CRP cutoff value of 10.96 mg/L. The areas under the receiver operating characteristic curves (ROC-AUCs) of PCT and CRP were 0.792 and 0.858, respectively (p < 0.05). CONCLUSIONS: PCT may not be a better predictor than CRP for diagnosing bacterial infection in elderly patients, but its high specificity is helpful to rule in a bacterial infection.

[Something's moving in chronic migraine]. / Algo se mueve en la migraña crónica.

TITLE: Algo se mueve en la migraña cronica.

In vitro induction of oocyte maturation and steroidogenesis by gonadotropins, insulin, calcitonin and growth factor in an estuarine flat head grey mullet, Mugil cephalus L.

In this article, an in vitro investigation was carried out to ascertain the roles of hormones and growth factor in the inductions of oocyte maturation and steroidogenesis of the postvitellogenic follicles in an Indian estuarine grey mullet, Mugil cephalus L. Oocyte maturation was evaluated by scoring the germinal vesicle breakdown (GVBD) percent of the postvitellogenic follicles. All the sex [17α,20ß-dihydroxy-4-pregnane-3-one (DHP), estradiol 17ß (E2), progesterone (P), 17α-OH progesterone (17-OH-P) and testosterone] and other [bovine-insulin and salmon-calcitonin, human chorionic gonadotropin (hCG), luteinizing hormone (LH) or hCG+DHP] hormones and insulin-like growth factor-I (IGF-I) significantly increased GVBD% in 9 h culture. DHP had a maximum effect (75 %) compared to other effectors. Some effectors (hCG: 82.14 %, LH: 78.94 %, hCG plus DHP: 81.81 %, E2: 80 % and IGF-I: 74.19 %) including DHP (79 %) further increased GVBD% in 15-h culture. All the hormones (except DHP) and IGF-I increased DHP, E2 and testosterone productions by the postvitellogenic ovarian follicles in vitro. DHP and testosterone productions were increased with the increase of incubation time from 9 h through 15 h. E2 production was not further increased beyond 12 h. DHP production was highest by hCG compared to other effectors. The hCG of all the test compounds was most effective in both the induction of GVBD% and steroid production. DHP is the most potent inducer of oocyte maturation in Indian estuarine flat head grey mullet. Involvement of estrogen in mullet oocyte maturation is indicated. hCG, like DHP, is equally potent and induces oocyte maturation via DHP production in vitro. hCG with DHP has synergistic action on oocyte maturation in mullet ovary. Interplay of several hormones (hCG, LH, and probably E2 and testosterone) and IGF-I on oocyte maturation is suggested in the mullet.

Utilidad de la procalcitonina y proteina C reactiva en la unidad de terapia intensiva pediatrica / Utility of procalcitonin and C-reactive protein in pediatric intensive care unit / Utilidade da procalcitonina e proteína C-reativa na unidade de terapia intensiva pediátrica

El objetivo de este trabajo fue evaluar la utilidad de la Procalcitonina (PCT) y Proteina C Reactiva (PCR) en pacientes pediatricos con sospecha de infeccion bacteriana o sepsis al ingreso a la Unidad de Terapia Intensiva Pediatrica (UTIP) y posterior seguimiento como pronostico de internacion prolongada o muerte en un hospital de tercer nivel. Se realizo un estudio prospectivo observacional, unicentrico. Punto final primario: se considero un punto final combinado de muerte hospitalaria o internacion prolongada en la UTIP (mayor de 12 dias). Se dosaron Procalcitonina (VIDASR BRAHMS PCT) y PCR (Ensayo turbidimetrico BT 3000) al ingreso y al tercer dia de internacion y se calculo el aclaramiento de ambos marcadores. De 41 pacientes, 24 (58%) fallecieron o tuvieron internacion prolongada. El aclaramiento de PCT y PCR al tercer dia se asocio significativamente con menos mortalidad y menos dias de Internacion en UTIP (p=0,01 para PCT; p=0,0036 para PCR). El area bajo la curva ROC de PCR fue 0,773 y de PCT 0,735, sin diferencias significativas entre ambas curvas, No hubo diferencias significativas entre los dos grupos para los valores al ingreso de PCT y PCR (p=0,82 y p=0,95 respectivamente). Se concluye que los valores del aclaramiento de ambos marcadores pueden ser una herramienta util para el pronostico clinico.

The aim of the present work was to evaluate the usefulness of procalcitonin and C-reactive protein in pediatric patients with suspected bacterial infection or sepsis on admission to the Pediatric Intensive Care Unit (PICU) and subsequent monitoring and prognosis of prolonged hospitalization or death in a third level hospital. A prospective observational, single center study was performed and a combined endpoint of hospital death or prolonged hospitalization in the PICU (over 12 days) was considered as primary end point. Values of Procalcitonin (VIDAS ® BRAHMS PCT) and PCR (BT turbidimetric 3000) were obtained on admission and on the third day of hospitalization and clearance of both markers was calculated. Out of 41 patients, 24 (58%) died or had prolonged hospitalization. PCT and CRP clearance on the third day was significantly associated with lower mortality and shorter hospital stays in PICU (p=0.01 for PCT, p=0.0036 for PCR). The area under the ROC curve was 0.773 for CRP and PCT was 0.735, with no significant difference between both curves. No significant differences were observed between both groups for the PCT and CRP values at admission (p=0,82 and p=0,95 respectively). It can be concluded that clearance values of both markers can be a useful tool for clinical prognosis.

O objetivo de avaliar a utilidade da Procalcitonina e Proteína C-Reativa em pacientes pediátricos com suspeita de infecção bacteriana ou sepse na admissão na Unidade de Terapia Intensiva Pediátrica (UTIP) e posterior acompanhamento e prognóstico de hospitalização prolongada ou morte em um hospital de terceiro nível. Foi realizado um estudo prospectivo observacional, único centro. Ponto final primário: foi considerado um ponto final combinado de óbito hospitalar ou hospitalização prolongada na UTIP (mais de 12 dias). Foi dosada Procalcitonina (VIDAS ® BRAHMS PCT) e PCR (ensaio turbidimétrico BT 3000) na admissão e no terceiro dia de internação e foi calculado como se aclararam ambos os marcadores. Dos 41 pacientes, 24 (58%) morreram ou tiveram internação prolongada. A aclaração do PCT e PCR no terceiro dia foi significativamente associado a menor mortalidade e menor tempo de internação em UTI (p=0,01 para PCT, p=0,0036 para PCR). A área sob a curva ROC foi de 0,773 para PCR e PCT foi 0,735, sem diferença significativa entre as duas curvas. Não houve diferença significativa entre os dois grupos para os valores de PCT e renda PCR (p=0,82 e p=0,95 respectivamente). Concluiu-se que os valores de aclaração de ambos os marcadores podem ser uma ferramenta útil para o prognóstico clínico.

Procalcitonin in pediatrics.

Over the past two decades, the body of literature on the clinical usefulness of procalcitonin (PCT) in adults has grown rapidly. Although this approach has led to increased insight, it has also prompted debate regarding its potential use in diagnosis and management of severe infection. Clinicians, however, are less familiar with the use of PCT in pediatric populations. In this review, we examine PCT as a marker of severe clinical pediatric conditions including its role in systemic inflammation, infection, and sepsis.

Calcitonin: physiology or fantasy?

Calcitonin, a potent hypocalcemic hormone produced by the C-cells of the thyroid, was first discovered by Harold Copp in 1962. The physiological significance of calcitonin has been questioned, but recent studies using genetically modified mouse models have uncovered additional actions of calcitonin acting through its receptor (CTR) that are of particular significance to the regulation of bone and calcium homeostasis. Mice in which the CTR is deleted in osteoclasts are more susceptible to induced hypercalcemia and exogenous calcitonin is able to lower serum calcium in younger animals. These data are consistent with the hypothesis that calcitonin can regulate serum calcium by inhibiting the efflux of calcium from bone, and that this action is most important when bone turnover is high. Calcitonin has also been implicated in protecting the skeleton from excessive loss of bone mineral during times of high calcium demand, such as lactation. This action may be linked to an intriguing and as yet unexplained observation that calcitonin inhibits bone formation, because deletion of the CTR leads to increased bone formation. We propose several mechanisms by which calcitonin could protect the skeleton by regulating bone turnover, acting within the bone and/or centrally. A new more holistic notion of the physiological role of calcitonin in bone and calcium homeostasis is required and we have highlighted some important knowledge gaps so that future calcitonin research will help to achieve such an understanding.

The role of procalcitonin in neonatal intensive care unit patients with candidemia.

Candidemia is a major infectious complication in neonatal patients. The isolation of yeasts from blood is still the "gold standard" for its diagnosis, but other laboratory markers (i.e., circulating antigens) have been studied with varying specificities and sensitivities. The aim of this study was to evaluate the role of procalcitonin for the diagnosis of candidemia in neonatal patients at high risk. To verify if the use of different commercial methods can highlight dissimilar results of sensitivity and/or specificity, the determination of procalcitonin serum levels was estimated by two systems. Overall, 90 patients from a Neonatal Intensive Care Units were enrolled, of whom six developed Candida bloodstream infection. Four of six infants with candidemia had slight increase of procalcitonin values (0.5-1 ng/mL). Only one baby showed very high levels but he had fungal and bacterial sepsis at the same time, while no elevation was observed in the sixth patient. No statistically significant difference was observed between two different methods at the time of monitoring (p>0.643). Both methods showed a sensitivity of 83.3 % at diagnosis, while the specificity was 73.8 and 63.1 % by methods A and B, respectively. In the light of the low sensibility and specificity of this assay, we can assume that the determination of procalcitonin would not seem to play a significant role in the diagnosis of fungal infection in neonatal patients.

The hook effect in calcitonin immunoradiometric assay: a case report.

UNLABELLED: The hook effect, which has long been detected and documented for immunoradiometric assays (IRMA) such as those measuring prolactin or thyroglobulin, occurs when the serum antigen level is extremely high, thus inducing a bias in the methodology of measurement. RESULTS: We report the case of an 80-year-old man with confirmed medullary thyroid carcinoma (MTC). In the case reported here, the clinical status of the patient contrasts with his tumor antigen, serum calcitonin (CT), concentrations. The measured increased CT concentrations revealed the presence of a hook effect. This phenomenon occurs due to an excess of antigen during the one-step IRMA where the signal antibodies, bound to the non-captured antigens, are washed out during the measurement, inducing the loss of signal. Aiming to prevent the "hook effect", successive dilutions of the same sample of serum were done. CONCLUSIONS: Previous studies have shown when one-step IRMA reveals high concentrations of a tumor serum antigen (i.e. prolactin or thyroglobulin), a two-step IRMA or a systematic 1:10 dilution of the serum sample prevents the formation of the "hook effect". In our case report, the CT "hook effect" formation was prevented by performing serial dilutions of the serum sample.

The role of procalcitonin in community-acquired pneumonia: a literature review.

Community-acquired pneumonia (CAP) is a significant clinical and public health problem. Recently, attention has been paid to the potential for procalcitonin (PCT) both to differentiate the diagnosis and to indicate the prognosis of pneumonia. The purpose of this literature review was to evaluate the eligibility of PCT for defining typical bacterial infections and for predicting severity and mortality in trials for CAP. The literature review suggests that PCT has the ability to supplement clinical information to determine whether or not the cause of the infection is likely to be bacterial. In addition, PCT seems to be superior to the most prevalent inflammatory biomarker C-reactive protein and also demonstrates a significant correlation between the current clinical scoring systems and actual mortality.