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In a population comprising 197 patients serum and CSF proteins were assayed using the radial immunodiffusion technique devised by Mancini. Multiple discriminant analysis was applied to investigate whether the measured CSF/serum protein relations and their ratios could be regarded as an indicator of specific neurologic diseases. One significant finding was that the slope angle alpha of the regression line between the serum/CSF relation and molecular weight may represent an important indicative parameter. A small angle is suggestive of enhanced permeability of the blood-brain barrier, a large angle of a correspondingly lowered permeability. Further, the analyses demonstrated that the combined use several predictors can markedly improve differential diagnosis. The study also demonstrates the potential of a statistical analytic technique that is still rarely applied in medicine.
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms. The lack of objective molecular biomarkers limits early diagnosis and personalized treatment. Here, we propose Essence, a benchmarking-validated framework integrating cerebrospinal fluid (CSF) proteomics with traditional and deep learning models to identify robust protein signatures for PD. Using data from two independent cohorts, 1266 high-confidence proteins are quantified, among which 178 exhibit differential abundance between PD and healthy controls (HC). Through systematic benchmarking of ten machine learning algorithms and four neural architectures, the Transformer model consistently outperforms alternatives across multiple feature selection strategies, achieving an area under the receiver operating characteristic curve (AUC) of 1.0000 with only 35 features. Functional analyses of the top-ranked 35 proteins reveal enrichment in neuroinflammatory, synaptic, and oxidative stress-related pathways. Importantly, spatial transcriptomic profiling based on the Allen Brain Atlas shows region-specific expression of these biomarkers in PD-relevant brain structures, including the striatum, subthalamic nucleus, hippocampus, and white matter tracts. This anatomical alignment supports the functional relevance of the identified markers and highlights their potential utility in early-stage diagnosis and mechanistic understanding of PD.
The correlation between age and CSF protein in 38 patients with pathologically proven motor neurone disease was the reverse of that described for normal subjects by Tibbling et al in 1977. Eight had CSF protein ranging from 0.75 g/1 to 1.52 g/L. These patients were younger, but other clinical and gross and light microscopy pathological features were not significantly different from those with lower CSF protein. Transudation from serum may be only one of the mechanisms underlying this elevation in CSF protein.
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The present study was designed to evaluate the potential of polyacrylamide disc electrophoresis of CSF proteins as an adjunct to laboratory diagnosis of neurological inflammatory diseases. The results of polyacrylamide and cellulose acetate electrophoresis of 42 CSF samples from control subjects and patients with various inflammatory diseases of CNS are presented. A comparison between results from both techniques is made. The polyacrylamide disc electrophoresis has been found valuable in the study of liquoral proteins with particular attention to gammaglobulins because this resolving power is superior to the other method. However, the Authors emphasize the importance of distinguishing the genetically determined proteins and haptoglobins and of the use of specific criteria in interpretation of a CSF protein pattern.
BACKGROUND: The aim of this study was firstly, to improve and validate a cerebrospinal fluid (CSF) prefractionation method followed by two-dimensional electrophoresis (2-DE) and secondly, using this strategy to investigate differences between the CSF proteome of frontotemporal dementia (FTD) patients and controls. From each subject three ml of CSF was prefractionated using liquid phase isoelectric focusing prior to 2-DE. RESULTS: With respect to protein recovery and purification potential, ethanol precipitation of the prefractionated CSF sample was found superior, after testing several sample preparation methods.The reproducibility of prefractionated CSF analyzed on 2-D gels was comparable to direct 2-DE analysis of CSF. The protein spots on the prefractionated 2-D gels had an increased intensity, indicating a higher protein concentration, compared to direct 2-D gels. Prefractionated 2-DE analysis of FTD and control CSF showed that 26 protein spots were changed at least two fold. Using mass spectrometry, 13 of these protein spots were identified, including retinol-binding protein, Zn-alpha-2-glycoprotein, proapolipoproteinA1, beta-2-microglobulin, transthyretin, albumin and alloalbumin. CONCLUSION: The results suggest that the prefractionated 2-DE method can be useful for enrichment of CSF proteins and may provide a new tool to investigate the pathology of neurodegenerative diseases. This study confirmed reduced levels of retinol-binding protein and revealed some new biomarker candidates for FTD.
We have evaluated the use of Coomassie Brilliant Blue (CBB) dye to measure the protein of urine and cerebral spinal fluid. The method was automated and compared with the turbidimetric method and with Ponceau S dye. With both the manual and automated procedures the CBB method could be used to protein concentrations of 160 mg/dl. Comparing this method to the method measuring the turbidity produced by trichloracetic acid (TCA) we found a correlation coefficient (r) of 0.96. The regression line was CBB = 0.84 TCA + 4.97. A similar comparison to the method using Ponceau S (PS) produced an r = 0.98 and the regression line, CBB = 0.91 P-S + 3.2. The CBB method was not as affected by turbidity in the samples or by xanthochromia as was the TCA Method. It is simpler to perform than the P-S method, since it does not require decantation. With the manual method, the coefficient of variation (CV) at 40 mg/dl for within-day determinations was less than 2% and, for between-day determinations, less than 4%. While the CV was somewhat higher with the ABA than with the manual method at 40 mg/dl, it was below 5% for both within-day and between-day determinations at the concentrations between 70 and 170 mg/dl. The method using CBB is useful as both a manual and automated procedure to measure protein in urine and cerebral spinal fluid.
Only few biological markers are currently available for the routine diagnosis of brain damage-related disorders including cerebrovascular, dementia, and other neurodegenerative diseases. In this study, post-mortem cerebrospinal fluid samples were used as a model of massive brain insult to identify new markers potentially relevant for neurodegeneration. The protein pattern of this sample was compared to the one of cerebrospinal fluid from healthy subjects by two-dimensional gel electrophoresis. Using gel imaging, N-terminal microsequencing, mass spectrometry, and immunodetection techniques, we identified 13 differentially expressed proteins. Most of these proteins have been previously reported to be somehow associated with brain destruction or with the molecular mechanisms underlying certain neurodegenerative conditions. These data indicate that the identified proteins indeed represent potential biomarkers of brain damage. We recently showed that H-FABP, a protein highly homologous to E-FABP and A-FABP identified in this study, is a potential marker of Creutzfeldt-Jakob disease and stroke.
To extrapolate the function of the leptomeninges, we examined the profile of the proteins secreted from the cultured leptomeningeal cells prepared from 1-2-day-old rats. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the medium conditioned with the cultured cells, 20-25 differentially distinctive protein bands were noted. Through several chromatographic procedures (Sephadex G-75, Mono Q, and 7C8-300), altogether 18 proteins were purified to homogeneity, and the partial amino acid sequence of each protein was determined. Homology search revealed that the major proteins included prostaglandin-D-synthase or beta-trace protein, insulin-like growth factor (IGF)-II, IGF-binding protein-2, apolipoprotein E, beta 2-microglobulin, cystatin C, transferrin, peptidyl-prolyl cis-trans isomerase or cyclophilin C, secreted protein acidic and rich in cysteine, ubiquitin, lysozyme C, extracellular superoxide dismutase, and collagen alpha-1 (III). Most of these proteins are known to be the major brain-derived protein constituents of CSF and are thought to play important roles in certain biological events in the brain. Considering the morphological features, the present findings suggest the importance of the leptomeninges as an origin of such proteins in CSF.
The introduction of acetylcholine esterase (AChE) inhibitors as a symptomatic treatment of Alzheimer's disease (AD) has made patients seek medical advice at an earlier stage of the disease. This has highlighted the importance of diagnostic markers for early AD. However, there is no clinical method to determine which of the patients with mild cognitive impairment (MCI) will progress to AD with dementia, and which have a benign form of MCI without progression. In this paper, the performance of cerebrospinal fluid (CSF) protein biomarkers for AD is reviewed. The diagnostic performance of the three biomarkers, total tau, phospho-tau, and the 42 amino acid form of beta-amyloid have been evaluated in numerous studies and their ability to identify incipient AD in MCI cases has also been studied. Some candidate AD biomarkers including ubiquitin, neurofilament proteins, growth-associated protein 43 (neuromodulin), and neuronal thread protein (AD7c) show interesting results but have been less extensively studied. It is concluded that CSF biomarkers may have clinical utility in the differentiation between AD and several important differential diagnoses, including normal aging, depression, alcohol dementia, and Parkinson's disease, and also in the identification of Creutzfeldt-Jakob disease in cases with rapidly progressive dementia. Early diagnosis of AD is not only of importance to be able to initiate symptomatic treatment with AChE inhibitors, but will be the basis for initiation of treatment with drugs aimed at slowing down or arresting the degenerative process, such as gamma-secretase inhibitors, if these prove to affect AD pathology and to have a clinical effect.
The CSF and sera of 17 patients with meningoencephalitis or encephalitis, 10 with meningitis or meningomyelitis, 5 subjects with postencephalitic sequelae and 2 with arachnoiditis were studied. Diseases involving the intracranial CNS parenchyma were found to give CSF electrofocusing findings differing from those of the other diagnostic subgroups. Differences regarding subfraction patterns of the gamma-globulin region seemed to be influenced of whether supra- or infratentorial structures were affected. The present study seems to indicate that the abnormal CSF-protein patterns found on electrofocusing were not only influenced by temporal but also by spatial factors.
Using C8 reversed-phase HPLC in conjunction with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we have fractionated proteins contained in human CSFs obtained from patients with schizophrenic disorders. When these proteins were electrophoretically blotted onto polyvinylidene difluoride membrane for direct N-terminal amino acid sequencing, several CSF proteins were identified; these included albumin, transferrin, apolipoprotein A-I, beta 2-microglobulin, and prealbumin. We have also identified two structurally related human CSF proteins designated cerebrin 28 (M(r) 28,000) and cerebrin 30 (M(r) 30,000) that have an N-terminal amino acid sequence of NH2-APPAQVSVQPNF and NH2-APEAQVSVQPLFXQ, respectively. Comparison of these sequences with existing database at Protein Identification Resource (R 32.0), GenBank (R 72.0), SWISS-PROT (R 22.0), and EMBL (R 31.0) indicated that they are unique proteins. These proteins were subsequently purified by high performance electrophoresis chromatography (HPEC) using an Applied Biosystems 230A HPEC system. A specific polyclonal antibody was prepared and an ELISA was established for cerebrin 30. It was noted that HPEC is a powerful tool to purify microgram quantities of proteins from human, rabbit, and rat CSFs. Using such a system, we have been able to micropurify as many as 10 proteins simultaneously in a single experiment because the elution of proteins occurred strictly according to their molecular weights. More importantly, we routinely obtained a recovery of > 90%. The potential use of this technology for micropurification of proteins was discussed.
A procedure using high-voltage isoelectric focusing (IF) in ultrathin (02. mm) gels and enzyme-amplified immuno-sandwich assay was elaborated to get optimal IF separation conditions, to avoid CSF concentration, e.g. by ultrafiltration preceding IF with the risk of unequal protein losses, to minimize the amounts of CSF and expensive reagents needed, especially antibodies and to shorten the analysis time, including the selective detection of proteins. The high voltage (2000-3000 V/10 cm) and efficient cooling during IF were obtained using ECPS 3000/150 and FBE 3000 (Pharmacia, Sweden). Ampholytes (Pharmalytes) of different pI intervals were used. The CSF and (diluted) serum samples were microdialysed in polyacrylamide gel before IF to minimize band curvature and to obtain optimal resolution. The IF separation was performed in about 1 h. Owing to the rapid fixation of ultrathin gels after IF, full use could be made of the high-voltage resolving capacity. The thin gels also made histochemical techniques applicable. Different immunological identification assays have been tested. An enzyme-amplified (alkaline phosphatase) immuno-sandwich method was found to be very sensitive and selective, and has so far given the best results. Many proteins in the same sample, applied as a line on the gel before IF, could be detected by overlaying antibody-soaked membrane strips. Furthermore, one specific protein could be examined in many samples simultaneously by overlaying or immersion of diluted antibody solutions. A few microlitres of unconcentrated CSF and diluted serum were used for the analysis performed within 1 day. The findings for albumin, transferrin and IgG in CSF and sera from patients with different neurological diseases, especially including cases with "normal" CSF, barrier damage, degenerative and demyelinating disorders, have been compared with the corresponding protein-stained (Coomassie R-250) patterns where the CSF had been concentrated by a special vacuum evaporation technique before IF.
This paper briefly reviews the factors which influence the concentrations of proteins, particularly immunoglobulins, within the CSF and how antibodies which are locally synthesized within the central nervous system can be detected by the laboratory. The use of nitrocellulose immunoblotting for the identification of antibodies which are specific to Treponema pallidum and Human Immunodeficiency Virus Type-1 are discussed.
Values of the liquor pherogram, which were obtained by means of electrophoresis on acetate folie and classified by disease groups and by the proportions of beta-globulin and first fraction, are compared, with respect to the absolute contents, by reference to tables and figures. The diagnostic importance of low total protein contents in the lumbar liquors of adults is considered in connection with a discussion of the usefulness of indicating the liquor pherogram in terms of percentage or absolute values.