S-100 protein and neuron-specific enolase in amniotic fluid as markers of abdominal wall and neural tube defects in the fetus

The Ca2+-Binding S100B Protein: An Important Diagnostic and Prognostic Neurobiomarker in Pediatric Laboratory Medicine

In recent decades a significant scientific effort has focused on projects regarding the use of neurobiomarkers in perinatal medicine with a view to understanding the mechanisms that interfere with physiological patterns of brain development and lead to ominous effects in several human diseases. Numerous potential neurobiomarkers have been proposed for use in monitoring high-risk fetuses and newborns, including markers of oxidative stress, neuroproteins, and vasoactive agents. Nonetheless, the use of these markers in clinical practice remains a matter of debate. Recently, the calcium-binding S100B protein has been proposed as being an ideal neurobiomarker, thanks to its simple availability and easy reproducibility, to the possibility of detecting it noninvasively in biological fluids with good reproducibility, and to the possibility of a longitudinal evaluation in relation to reference curves. The present chapter contains an overview of the most significant studies on the assessment of S100B in different biological fluids as a trophic factor and/or marker of brain damage in high-risk fetuses and newborns.

Tethered Cord Syndrome-A Study of the Short-Term Effects of Surgical Detethering on Markers of Neuronal Injury and Electrophysiologic Parameters

OBJECTIVE

Several studies have assessed clinical and radiologic outcomes after detethering of the cord for tethered cord syndrome (TCS). However, no data regarding the impact of detethering on the metabolism or electrophysiologic functioning of the cord are available. The aim of this study was to assess the changes in the cerebrospinal fluid (CSF) levels of markers of neuronal injury and alterations in the electrophysiologic functioning of the spinal cord after detethering.

METHODS

This prospective study included patients with congenital TCS. Patients underwent clinical assessment, magnetic resonance imaging, somatosensory evoked potentials (SSEP) study, and CSF biochemical analysis (to estimate lactate, glial fibrillary acidic protein, and S100B levels), before and 3 months after surgery. Clinical and radiologic outcomes were assessed. We studied changes in biochemical and electrophysiologic parameters before and after detethering as surrogate markers for the effects of this intervention.

RESULTS

Twenty-one patients were recruited over 2 years. Detethering led to clinical improvement in 75% of patients with motor deficits, 60% of patients with bladder symptoms, and 50% of patients with gait problems. At 3 months follow-up, 43% (median) of the preoperative vertical tethering was found to be corrected. There was significant reduction in CSF lactate, glial fibrillary acidic protein, and S100B levels as well as a significant decrease in the latencies of the SSEP waves 3 months after surgery.

CONCLUSIONS

Surgical detethering led to a reduction in the CSF levels of the markers of anaerobic metabolism and neuronal injury. There was also a reduction in the latencies of the SSEP waves, indicating better electrophysiologic functioning of the cord.

Nucleofection is highly efficient for transfecting genes into murine embryonic palatal mesenchymal cells in primary culture

Non-syndromic cleft of the lip and/or palate is one of the most common birth defects in humans. Embryonic palatal mesenchymal (EPM) cells are an attractive source for investigating embryonic palatal development. In this study, we developed a highly efficient transfection method for murine EPM (MEPM) cells. MEPM cells were transfected with the plasmid pEGFP-N1 using two non-viral methods: nucleofection and lipofection. Nucleofection provided a much better rate of gene transfer than lipofection particularly in MEPM cells. The methylenetetrahydrofolate reductase (MTHFR) gene is an important candidate for involvement in the pathogenesis of this birth defect. The RNA interference plasmid of MTHFR was constructed and nucleofected into MEPM cells. Successful transfection resulted in a remarkable reduction in the expression of MTHFR. Taken together, the results indicate that nucleofection is highly efficient for MEPM cell transfection, and that this approach may be useful for investigating gene function in the process of palatogenesis.

Serum S100B levels in patients with neural tube defects

BACKGROUND

We investigated the levels of S100B protein in the serum of patients with neural tube defects (NTD), and the ontogenetic variation on this group of patients.

METHODS

Samples from 24 control individuals and 25 patients with NTD were studied. S100B protein levels were determined using LIA-mat Sangtec kit.

RESULTS

We observed no difference between the levels of S100B in NTD patients (median 0.860 microg/l) and control individuals (median 0.580 microg/l). When groups were classified according to age, decreased levels were observed in subjects > or = 4 y compared to the younger ones, on the control group; no significant difference was observed when the same comparison is performed on the group of patients with NTD.

CONCLUSIONS

This study indicates that the serum concentration of S100B in patients with NTD is similar to that of normal individuals; however, patients with NTD do not show the negative correlation with age which was observed on normal individuals.

Specificity and sensitivity of S100B levels in amniotic fluid for Down syndrome diagnosis

Down syndrome (DS) is the most common chromosomal abnormality and is associated with an extra copy of the chromosome 21. Although several markers are commonly used during pregnancy for the screening of DS, the definitive diagnosis is based on karyotype after amniocentesis, which is an expensive and laborious analysis. S100B is an astrocyte protein which had its gene mapped to the long arm of chromosome 21. Previous preliminary reports have found increased levels of this protein in the amniotic fluid of DS gestations. Aiming to achieve a simpler and cheaper test then karyotype to perform prenatal diagnosis of DS, here we have extended our previous studies and evaluated the real usefulness of amniotic S100B measurement for prenatal DS diagnosis. We have measured S100B in amniotic fluid of 96 pregnancies with DS and of 50 normal pregnancies. Pregnancies with DS presented significantly higher amniotic fluid S100B levels (M = 1.16 ng/mL; IQ = 0.83/1.78) than normal pregnancies (M = 0.51 ng/mL; IQ = 0.38/0.83) (p < 0.0001). A receiver operating characteristic (ROC) curve was performed to evaluate the sensitivity and specificity of S100B for DS diagnosis, and presented an area under the curve (AUC) of 0.82, indicating that S100B could be a reliable marker of DS. Moreover, values above 1.67 ng/mL were present only in DS fetuses, representing about 30% of affected pregnancies. However, as an overlap of values was observed between normal and DS gestations, we concluded that amniotic S100B alone is not a good test to discard DS diagnosis.

S100B testing in pregnancy

Follow-up studies have shown that the vast majority of neurological abnormalities present during childhood can have a prenatal or perinatal origin. It is relevant, therefore, to investigate the timing of adverse insults in the search for measures of prevention. However, such knowledge is still incomplete and subject to debate. Until recently, clinical-laboratory assessment was based essentially on biochemical aspecific parameters, ultrasound and Doppler patterns, and the determination of blood pH and gases. However, the measurement of brain constituents may offer a direct indicator of cell damage in the nervous system. The S100B protein, a calcium-binding protein highly concentrated in the nervous system, appears to meet the criteria required of such a marker in prenatal and perinatal medicine for its reproducible, simple and sensible measurements. Results in high-risk pregnancies demonstrated that S100B concentration increased in amniotic fluid and in cord blood of fetuses with brain damage. In addition, S100B protein has been also usefully employed to monitor the effects of maternal-antenatal therapy, such as NO and glucocorticoid administration. It appears also to be relevant that a neurotrophic role has been hypothesized for the protein, which in fact exhibits in amniotic fluid, in cord blood and in placenta patterns of concentration related to the gestational age.

S100B protein in biological fluids: a tool for perinatal medicine

The diagnosis of perinatal insults currently relies on adequate documentation of general medical and obstetric factors and on radiologic and laboratory assessments. The measurement of brain constituents such as S100B protein may offer an alternative and direct indicator of cell damage in the nervous system when clinical and radiologic assessments are still silent and has the additional advantage of providing a quantitative indicator of the extent of brain lesions. S100B protein has been measured by several immunoassays in biological fluids (i.e., cerebrospinal fluid, blood, amniotic fluid, and urine) from fetuses and newborns at high risk of perinatal brain damage. S100B protein in biological fluids increased at an early stage when standard monitoring procedures were still silent in the study populations that later developed brain damage. S100B concentration was also significantly correlated with the extent of brain lesions. S100B protein appears to satisfy the criteria for a marker for brain injuries in perinatal medicine: (a) simple to perform measurements with good reproducibility; (b) detection in a variety of biological fluids, possibly reducing perinatal stress related to testing; (c) possible use in longitudinal monitoring because of its 1-h half-life; and (d) well-established use as an early and quantitative marker of brain lesions/damage. Finally, because of the neurotrophic role putatively played by S100B, its measurement in biological fluids at pre-/perinatal ages makes it a candidate for the laboratory evaluation of brain maturation.

Tumour-associated antigens in maternal and fetal blood

Normal levels of cancer-associated antigen (CA) 19-9, neurone-specific enolase (NSE), cancer-associated antigen (CA) 125, and mucin-like carcinoma-associated antigen (MCA) during pregnancy were determined in 87 mothers and fetuses, using a solid-phase sandwich enzyme immunoassay. CA 19-9 concentrations were higher in the fetuses, whereas the other three tumour-associated antigen levels were higher in the mothers. Only fetal NSE and MCA levels were positively correlated with those in maternal serum. Contrary to adult samples, no difference was demonstrated between male and female fetal levels of CA 125. MCA was the only maternal marker that increased significantly with gestational age between 20 and 34 weeks' pregnancy.

Antenatal detection of neural tube defects: comparison of biochemical and immunofluorescence methods

The aim of this study was to determine whether identification of glial cells in amniotic fluid samples could form a useful supplementary test in the antenatal diagnosis of neural tube defects (NTDs). In a 5-year study, 1452 samples of middle trimester amniotic fluid were examined blind to the results of other antenatal diagnostic tests and to the outcome of pregnancy. Reason of amniocentesis included raised serum alpha-fetoprotein (329), previous NTD (73), and a family history of NTDs (71). Duplicate cytospin preparations were stained with Giemsa and an antibody to glial fibrillary acidic protein (GFAP), and on this basis a prediction of fetal NTD status was made which was not communicated to clinicians. Subsequent management of pregnancies was influenced only by the results of routine antenatal testing for NTDs. Twenty cases of NTDs occurred among the 1406 cases in which the outcome was subsequently known. Of these 20 cases, only five (four anencephalic, one spina bifida) were correctly predicated by immunofluorescent identification of GFAP-positive cells in the amniotic fluid. The remaining 15 cases (two anencephalic, 13 spina bifida) were not so identified. In a further 18 cases, apparently GFAP-positive cells were identified in the absence of NTDs. We conclude that GFAP immunofluorescence examination of routine amniocentesis samples of amniotic fluid is not a useful predictive test for NTDs.

Effect of chronic pre- and post-natal low-dose ethanol exposure on brain enolase isoenzyme activities

Sprague-Dawley dams were treated with 3 v/v % ethanol in liquid diet from the 8th day gestation through 3 weeks nursing period. Offsprings, ages 1, 2 and 3 weeks, and their dams were studied. Brain weights and their total proteins were not affected by this ethanol treatment. Total enolase activity/mg protein and its isoenzymes, i.e. non-neuron-specific, hybrid and neuron-specific, (mumol/min/mg protein) in 100,000 g supernate, were significantly lower in the treated. Additionally, enolase isoenzyme transformation was delayed.

Changes of neuron-specific enolase concentration in plasma after cardiac arrest and resuscitation

The concentration of neuron-specific enolase (NSE) was measured in plasma of 18 patients after cardiac arrest and resuscitation (14 nonsurvivors and 4 survivors). In all patients, the NSE concentration was significantly higher in comparison to reference values. The highest concentration was measured in nonsurvivors. Time-course investigation in the first 24 h after cardiac arrest was performed in five patients. Two nonsurvivors and one survivor of the five patients showed a significant rise, and a NSE peak concentration of 42.7 micrograms/L, 13.6 micrograms/L, and 10.5 micrograms/L, respectively, was found 10-19 h after cardiac arrest.

Detection of neuron specific enolase concentrations in cerebrospinal fluid from patients with neurological disorders by means of a sensitive enzyme immunoassay

An enzyme linked immunosorbent assay (ELISA) for the detection of neuron specific enolase (NSE) in cerebrospinal fluid (CSF) was developed. The sensitivity of the ELISA was less than 1 microgram/ml. This sensitivity is comparable with radioimmunoassays which have the disadvantage that radiolabelled products are used. The developed assay was used to measure cerebrospinal fluid neuron specific enolase (CSF-NSE) levels in 1178 patients with neurological disorders to establish its potential usefulness and clinical application. CSF-NSE levels in this group of patients were independent of sex and no correlation with age was found. CSF-NSE was significantly increased in Creutzfeldt-Jacob disease, meningeal hemorrhage, thrombosis, Guillain-Barré syndrome and in schizophrenia.