APPLICATIONS OF NEW LABORATORY MARKER ASSAYS IN NEUROLOGICAL DIAGNOSES – A PILOT STUDY

225 consecutive patients with different neurological diseases and 101 individuals as the control were examined between 2002–2004. Cystatin C, arginase-I, τ-protein and β-amyloid were measured. Individuals with CNS inflammation had significantly lower Cystatin-C index (CSF/serum) values. There was no diagnostic significance of the Arginase-I assay in CSF was verified. The CSF τ-protein/β-amyloid index was shown to be a sufficient efficacy for neurodegenerative disease diagnosis.


INTRODUCTION
There is much current information on the use of new laboratory markers in the diagnosis of some neurological diseases primarily about degenerative and inflammatory origin.
Simple analysis of cerebrospinal fluid (CSF) laboratory markers has only limited significance but recently published information deals with diagnostic use of the entire CSF markers.
The first aim of our work was diagnostic evaluation of CSF cystatin C and arginase-I analysis in individuals with various neurological diagnoses.

METHODS
CSF samples were drawn from the patients for diagnostic reasons.The serum and Cfs samples were separated in a cooled centrifuge at 4 0 C with 3000 g and subsequently frozen at -80 0 C for ELISA analysis.CSF total τ−protein (ELISA, Biosource, UK) CSF βamyloid (ELISA, Innogenetics, Belgium), CSF Arginase-I (ELISA, Biovendor, Brno, the Czech Republic), serum and CSF Cystatin-C concentrations (ELISA, Biovendor, Brno, The Czech Republic) were performed on all individuals, too.Cystatin C was determined with satisfying analytical parameters (intrassay coefficient of variation (CV) = 4.9 %, interassay CV = 9.1 %).Concentrations of Arginase-I, Cystatin C, total τ−protein and β-amyloid were determined after defrosting during the course of one day.
The study was approved by the ethics commission of the Hospital Šternberk and the Medical Faculty UP Olomouc.
The data obtained were processed by means of the software Medcalc (Medcalc, Mariakerke, Belgium).The value p < 0.05 was considered as statistically significant.

Cystatin-C in serum:
individuals with neurodegenerative diseases (NDD, n = 34) had the lowest Cystatin-C values of all subgroups (median 0.69 mg/l) but values did not significantly differ between groups.
Cystatin-C in CSF: values did not significantly differ.
Diagnostic efficacy for polyneuropathy diagnosis was not sufficient.
Arginase-I in CSF: no significant differences were detected in concentrations between groups.57 % of As a secondary finding we also show significant diagnostic efficacy of τ-protein/β-amyloid indexes in patients with neurodegenerative CNS diseases; diagnostic sensitivity in index value > 0.5 was 69 % and specificity 74 % (AUC 0.76) (Fig. 2).

CONCLUSIONS
225 consecutive patients and 101 individuals without neurological diseases from the clinical departments of the Sternberk Hospital and the Institute of Neurology Faculty Hospital Olomouc were examined between 2002-2004.

Fig. 1 . 2 .
Fig. 1.Index Cystatin C ROC for CNS inflammation Fig. 2. Index Csf τ-protein/β-amyloid ROC for neurodegenerative CNS diseases Individuals with CNS inflammation have significantly lower Cystatin-C index values.Cystatin-C index assay is for inflammation CNS diagnosis sufficiently effective.No diagnostic significance of Arginase-I assay in CSF was verified in patients with inflammatory or autoimmune CNS diseases.τ-protein/β-amyloid index in CSF was proven to be a sufficient efficacy for NDD diagnosis.AKNOWLEDGEMENT This study was supported by grant IGA NF/7480-3 from the Ministry of Health of the Czech Republic.