| CJD belongs to a family of neurodegenerative disorders. Thecommonest human prion disease is sporadic Creutzfeldt-Jakobdisease (sCJD), with on approximate incidence of one patient permillion inhabitants per year. Diagnosis of CJD can only be definitedat postmortem examination or brain biosy showing the pathologicalisform of prion protein (PrPsc). Brain biopsy, however, is notaccepted by patients. Because of the detection of 14-3-3 protein in CSF and the highsensitivity and specificity validated by large number of studies,14-3-3 protein has be used as a differential diagnostic marker forsCJD by WHO. The common assay detected 14-3-3 protein for diagnosis ofCJD in clinical is western blotting. This assay is subject to a numberof analytical and interpretative problems. The most serious of theseis the difficulty in assay standardization. There is no recognizedinternational standard against which all patient samples can becompared. This means that the detection of low concentrations ofCSF14-3-3, where the Western blot only shows faint bands, can bedifficult and the assesment of the significance of these bands is alsosubjective. However, there is a small group of patients in whomsequential testing gives rise to contradictory results: one timenegative and the other time weak positive. These results, togetherwith the absence of a world wide standard, can give rise todifficulties in interpretation. To avoid the person to person bias of avisual inspection of the blot, we present a quantitative 14-3-3 captureassay, which used a synthetic phosphoserine peptide instead of anantibody to capture the 14-3-3 protein. This peptide binds with theactive site of the 14-3-3 protein.We analysised cerebrospinal fluid (CSF) samples of 36 patientsfor 14-3-3 protein. In the group of 14 patients with CJD, the 14-3-3protein concentration in CSF were significantly higher than in twocontrol groups of patients with other dementia diseases and Nondementia diseases.Calculating the cut-off point for the group of CJD, best resultswere obtained at a level of 9ng/ml. At this cut-off point, sensitivityfor diagnosis of CJD is86.7%and specificity is86.4%, The positivepredictive value is81.3%and the negative predictive value is90.5%,respectively.The concentrations of 14-3-3 protein in CSF may be relevant tothe rate of progression of disease. The relatively slower progressionmay give rise to lower concentrations of brian protein. Patients withPSD in the EEG have the high 14-3-3 levels in the CSF, Theconcentrations of 14-3-3 protein are 105ng/ml, 48ng/ml,155ng/mland 130ng/ml. So we considered the concentration of14-3-3 protein in CSF is probably related to the rapidly clinicaldeterioration and the extensive brain tissue damage, But has norelated to disease duration and the clinical fatures.Two difinited CJD patients based on PRNP genotype at codon129 are M129M and M129V. The concentrations of 14-3-3 proteinare9ng/mland130ng/ml, We compared them and found the 14-3-3varied in different molecular subtypes of sCJD.The method was validated in CSF samples from patientssuspected of having CJD. A statistically significant in crease wasshown in CSF 14-3-3 level of patients with definite and probableCJD versus OD and ND. When appropriately applied to patientsfulfilling clinical criteria for possible CJD, this assay has a highsensitivity and specificity and supports a clinical diagnosis of CJD.The capture assay that quantifies 14-3-3 protein in CSF wasdeveloped. Its quantitative nature yields greater information inlongitudinal studies. It tells us about the magnitude and duration ofthe proteins presence.Besides this, we also analyzed the NSE in cerebrospinal fluidand Serum. The similar results have been achieved. Calculating thecut-off point for the group of CJD in CSF, best results were obtainedat a level of 35ng/ml. At this cut-off point, sensitivity for diagnosisof CJD is71.4%and specificity is86.4%, The positive predictivevalue is76.9%and the negative predictive value is82.6%,respectively.Comparing 14-3-3 and NSE, we found that 14-3-3 protein hashigher sensitive and specific than NSE in diagnosis of sCJD. Weconclude that NSE and 14-3-3 protein assays in the CSF are a usefuladjunct to confirm CJD.The combination of CSF 14-3-3 protein andincreased CSF NSE had a sensitivity of 90%and specificity 92.86%.All in all, in highly selected patients, where clinical signs andsymptoms are compatible and proper measures have been taken toexclude encephalitis or stroke, increased 14-3-3 and NSE cansupport a diagnosis even in the absence of characteristic EEG orMRI changes.The 14-3-3 proteins are a family of highly homologous proteinsthat are expressed in all eukaryotic cells. In addition to CJD, 14-3-3proteins have been reported to be elevated in the CSF from patientswith other neurological disease. We performedimmunohistochemical studies on 14-3-3 proteins in brain tissuespecimens from patients with sCJD using anti 14-3-3 antibody. Wefound that in contrast, cortical neurons and glial cells showed noimmunoreactivity. But in sCJD, 14-3-3 immunor-eactivity was inthe cortical neurons, both astrocytes and oligodend-rocytesexhibited 14-3-3 immunoreactivity. Our foundings support thehypothesis that acute neuronal damage may be the main cause of theelevation of 14-3-3 proteins in the CSF from patients with sCJD.14-3-3 proteins are associated with diverse cellular signal pathwaysthrough phosphorylation-dependent protein-protein interactions.inour study, we observed both the neuronal and glial componentscontained 14-3-3 immunoreactivity in the brains from the sCJDcases. These resultssuggest that 14-3-3 may regulate aconformational transition of PrPc to PrPsc.The enhanced expression of 14-3-3 proteins in glial cellssuggested that, although the abnormal 14-3-3 accumulation in theglial components was not specific. There may be a commonpathological process associated with 14-3-3 proteins in prion-relateddiseases. |
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