A two-dimensional electrophoretic study of serum amyloid A and C-reactive protein in infants and children

Reference intervals for serum amyloid A, haptoglobin, ceruloplasmin, and fibrinogen in apparently healthy neonatal lambs

BACKGROUND

Acute-phase proteins (APPs) are considered biomarkers for diagnoses, prognoses, and treatment and health status monitoring. Reference intervals (RIs) are an integral part of diagnostic laboratory testing and clinical decision-making. The RIs for neonatal lambs are lacking.

OBJECTIVE

This study aimed to determine the RIs of serum amyloid A (SAA), haptoglobin (Hp), ceruloplasmin (Cp), and fibrinogen (Fb) concentrations in neonatal cross-bred Kivircik lambs.

METHODS

The study consisted of 42 neonatal cross-bred Kivircik lambs. Physical examinations were performed daily, and blood samples were collected at 0 (precolostrum), 1, 3, 7, 14, 21, and 28 days of age. The RIs of SAA, Hp, Cp, and Fb concentrations were calculated according to the recommendation of the American Society for Veterinary Clinical Pathology. Results were also evaluated for age- and sex-related effects.

RESULTS

The RI for serum Hp was 0-0.4 g/L, and no apparent effect of age or sex was noted. Because of significant age- and sex-related differences, the SAA (0.34-55.12 µg/mL), Cp (2.4-26.07 mg/mL), and Fb (218.86-527.82 mg/mL) results were given as minimum and maximum values. Serum SAA on the 1st, 3rd, and 7th days of life, and Cp and Fb concentrations on the 14th and 21st days of life, were significantly higher than those on other study days.

CONCLUSIONS

This study is the first to establish RIs for neonatal lambs, and the values obtained could be useful for making clinical decisions regarding cross-bred Kivircik lambs during this critical period.

Transferrina como marcador de maturação pulmonar em cordeiros nascidos a termo ou prematuros

RESUMO O objetivo do estudo foi procurar proteínas de fase aguda que possam indicar sinais de maturação no neonato prematuro, por meio da quantificação sérica delas. Identificou-se a imunoglobulina A, a ceruloplasmina, a haptoglobina, a glicoproteína ácida, a transferrina, a albumina e as imunoglobulinas G de cadeias leve e pesada, pela comparação do perfil dos proteinogramas de cordeiros nascidos a termo com os prematuros submetidos a diferentes protocolos terapêuticos, a fim de estimular a atividade respiratória. Constituíram-se seis grupos: PN (n= 9): nascidos de parto normal; CN (n= 7): nascidos de cesariana em tempo normal de gestação; CP (n= 6): nascidos de cesariana prematura sem nenhum tipo de tratamento; DEX (n= 9): prematuros cujas mães receberam dexametasona pré-parto; SURF (n= 6): prematuros tratados com surfactante; e DEXSURF (n= 6): prematuros tratados com surfactante cujas mães receberam dexametasona pré-parto. As avaliações foram realizadas nos momentos imediatamente após o nascimento (M0), após 24 (M24) e após 48 horas (M48). As amostras foram processadas por meio de eletroforese em gel de poliacrilamida contendo dodecil sulfato de sódio (SDS-PAGE). A albumina, as imunoglobulinas e a proteína total dos cordeiros tiveram elevação após a ingestão de colostro. Maiores valores séricos de transferrina são referentes a maior período gestacional, podendo essa proteína ser utilizada como marcador de maturação neonatal.

Prospective observational study in two Dutch hospitals to assess the performance of inflammatory plasma markers to determine disease severity of viral respiratory tract infections in children

INTRODUCTION

Respiratory viruses causing lower respiratory tract infections (LRTIs) are a major cause of hospital admissions in children. Since the course of these infections is unpredictable with potential fast deterioration into respiratory failure, infants are easily admitted to the hospital for observation. The aim of this study was to examine whether systemic inflammatory markers can be used to predict severity of disease in children with respiratory viral infections.

METHODS

Blood and nasopharyngeal washings from children <3 years of age with viral LRTI attending a hospital were collected within 24 hours (acute) and after 4-6 weeks (recovery). Patients were assigned to a mild (observation only), moderate (supplemental oxygen and/or nasogastric feeding) or severe (mechanical ventilation) group. Linear regression analysis was used to design a prediction rule using plasma levels of C reactive protein (CRP), serum amyloid A (SAA), pentraxin 3 (PTX3), serum amyloid P component and properdin. This rule was tested in a validation cohort.

RESULTS

One hundred and four children (52% male) were included. A combination of CRP, SAA, PTX3 and properdin was a better indicator of severe disease compared with any of the individual makers and age (69% sensitivity (95% CI 50 to 83), 90% specificity (95% CI 80 to 96)). Validation in 141 patients resulted in 71% sensitivity (95% CI 53 to 85), 87% specificity (95% CI 79 to 92), negative predictive value of 64% (95% CI 47 to 78) and positive predictive value of 90% (95% CI 82 to 95). The prediction rule was not able to identify patients with a mild course of disease.

CONCLUSION

A combination of CRP, SAA, PTX3 and properdin was able to identify children with a severe course of viral LRTI disease, even in children under 2 months of age. To assess the true impact on clinical management, these results should be validated in a prospective randomised control study.

Serum amyloid A is increased in children with abusive head trauma: a gel-based proteomic analysis

BACKGROUND

Abusive head trauma (AHT) is the leading cause of death from traumatic brain injury in infants and young children. Identification of mild AHT (Glasgow Coma Scale score: 13-15) is difficult because children can present with nonspecific symptoms and with no history of trauma.

METHODS

Two-dimensional difference gel electrophoresis combined with mass spectrometry was used to compare the serum protein profile of children with mild AHT and age-matched controls. Protein changes were confirmed by western blots. Western blots were performed using serum from children with mild, moderate, and severe AHT to assess the effect of injury severity on protein intensity. The protein identified--serum amyloid A (SAA)--was then measured by enzyme-linked immunosorbent assay.

RESULTS

Using serum from 18 mild AHT cases and 20 controls, there were ~1,000 protein spots; 2 were significantly different between groups. Both spots were identified as SAA. There was no relationship between protein levels and injury severity. SAA concentrations measured by enzyme-linked immunosorbent assay were increased in cases vs. controls.

CONCLUSION

SAA may be a potential biomarker to identify children with mild AHT who present for medical care without a history of trauma and who might otherwise not be recognized as needing a head computed tomography.

Enrichment of serum amyloid proteins by hydrophobic interaction chromatography combined with two-dimensional electrophoresis with immobilised pH gradients

Serum amyloid A protein was subjected to one-step octyl-Sepharose extraction in three different dimensions. Elution was performed partly without UV recording, and with urea or guanidine-based buffers. The eluent was applied directly to denaturing two-dimensional electrophoresis with immobilised pH gradient, or octyl-Sepharose extracted fractions were pooled and lyophilised before application. Proteins were characterised by N-terminal analysis or mass spectrometry. In most of the species that were studied, previously undescribed serum amyloid proteins were detected. Compared to conventional strategies, the presented techniques are more rational and yield more comprehensive information. The presented data also provide a basis for novel perspectives regarding certain inflammatory conditions.

Serum amyloid A protein in the early detection of late-onset bacterial sepsis in preterm infants

In order to evaluate serum amyloid A as an early diagnostic marker of late-onset sepsis, seventy-nine preterm infants with clinically suspected sepsis and 40 healthy matched controls were assayed for serum amyloid A. In parallel, clinical and biochemical variables that are used to evaluate neonatal sepsis were compared. Forty-two episodes were diagnosed as sepsis. Serum amyloid A levels were elevated in the sepsis group (187.6 +/- 78.3 micrograms/ml), compared with infants who had no sepsis (10.2 +/- 8.3 micrograms/ml) and the control group (6.9 +/- 3.3 micrograms/ml), and were significantly higher in gram-negative compared to gram-positive sepsis (221.8 +/- 84.4 micrograms/ml vs. 48.5 +/- 22.2 micrograms/ml). Analysis of the data suggests serum amyloid A has the highest sensitivity (100%), specificity (93%) and positive predictive value (96%) for sepsis among the clinical and biochemical parameters that were tested. In conclusion, serum amyloid A seems to be a reliable early marker for the diagnosis of late-onset sepsis in preterm infants.

The human plasma proteome: history, character, and diagnostic prospects

The human plasma proteome holds the promise of a revolution in disease diagnosis and therapeutic monitoring provided that major challenges in proteomics and related disciplines can be addressed. Plasma is not only the primary clinical specimen but also represents the largest and deepest version of the human proteome present in any sample: in addition to the classical "plasma proteins," it contains all tissue proteins (as leakage markers) plus very numerous distinct immunoglobulin sequences, and it has an extraordinary dynamic range in that more than 10 orders of magnitude in concentration separate albumin and the rarest proteins now measured clinically. Although the restricted dynamic range of conventional proteomic technology (two-dimensional gels and mass spectrometry) has limited its contribution to the list of 289 proteins (tabulated here) that have been reported in plasma to date, very recent advances in multidimensional survey techniques promise at least double this number in the near future. Abundant scientific evidence, from proteomics and other disciplines, suggests that among these are proteins whose abundances and structures change in ways indicative of many, if not most, human diseases. Nevertheless, only a handful of proteins are currently used in routine clinical diagnosis, and the rate of introduction of new protein tests approved by the United States Food and Drug Administration (FDA) has paradoxically declined over the last decade to less than one new protein diagnostic marker per year. We speculate on the reasons behind this large discrepancy between the expectations arising from proteomics and the realities of clinical diagnostics and suggest approaches by which protein-disease associations may be more effectively translated into diagnostic tools in the future.

Functional analysis of a minimal mouse serum amyloid A3 promoter in transgenic mice

We report the generation of transgenic mice harboring the SAA3/LacZ transgene and analysis of its expression patterns in vivo following LPS-induced inflammation. Our results show that a 210-bp fragment of the mouse SAA3 promoter when placed in front of the LacZ gene was sufficient to confer basal and inflammation-induced reporter gene expression. Consistent with endogenous SAA3 expression, the basal level of LacZ expression was high in the lung and liver of newborn and 1-week-old transgenic mice. Its expression however decreased with increasing age and at 3-weeks ofage, LacZ expression was very low in the lung and was essentially undetectable in the liver. When SAA3/LacZ transgenic mice were injected with lipopolisaccharide to induce inflammation, beta-gal activities were increased approximately 6- and 16-fold in the lung and liver, respectively. Histological examination of lung and liver tissues stained with X-gal revealed that the LacZ transgene was expressed primarily in the macrophages. Thus, this minimal SAA3 promoter fragment contains the necessary regulatory sequences for its expression and cytokine responsiveness in macrophages albeit is insufficient to confer expression in hepatocytes.