A protein panel in cerebrospinal fluid for diagnostic and predictive assessment of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disease with heterogenous pathophysiological changes that develop years before the onset of clinical symptoms. These preclinical changes have generated considerable interest in identifying markers for the pathophysiological mechanisms linked to AD and AD-related disorders (ADRD). On the basis of our prior work integrating cerebrospinal fluid (CSF) and brain proteome networks, we developed a reliable and high-throughput mass spectrometry-selected reaction monitoring assay that targets 48 key proteins altered in CSF. To test the diagnostic utility of these proteins and compare them with existing AD biomarkers, CSF collected at baseline visits was assayed from 706 participants recruited from the Alzheimer's Disease Neuroimaging Initiative. We found that the targeted CSF panel of 48 proteins (CSF 48 panel) performed at least as well as existing AD CSF biomarkers (Aß42, tTau, and pTau181) for predicting clinical diagnosis, FDG PET, hippocampal volume, and measures of cognitive and dementia severity. In addition, for each of those outcomes, the CSF 48 panel plus the existing AD CSF biomarkers significantly improved diagnostic performance. Furthermore, the CSF 48 panel plus existing AD CSF biomarkers significantly improved predictions for changes in FDG PET, hippocampal volume, and measures of cognitive decline and dementia severity compared with either measure alone. A potential reason for these improvements is that the CSF 48 panel reflects a range of altered biology observed in AD/ADRD. In conclusion, we show that the CSF 48 panel complements existing AD CSF biomarkers to improve diagnosis and predict future cognitive decline and dementia severity.

Clinical characteristics of autoimmune GFAP astrocytopathy.

The clinical features of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy remain to be elucidated. We describe here the clinical features of 14 patients with GFAP astrocytopathy confirmed by detection of GFAP-IgG in cerebrospinal fluid (CSF). The novel findings of this study are as follows. First, over half of the patients presented with movement disorders (tremor, myoclonus, and ataxia), autonomic dysfunction (mainly urinary dysfunction), and hyponatremia. Second, most patients showed transient elevation of adenosine deaminase activity levels in CSF. Finally, some patients showed bilateral hyperintensities in the posterior part of the thalamus on brain magnetic resonance imaging.

Comparative Assessment of the Prognostic Value of Biomarkers in Traumatic Brain Injury Reveals an Independent Role for Serum Levels of Neurofilament Light.

Traumatic brain injury (TBI) is a common cause of death and disability, worldwide. Early determination of injury severity is essential to improve care. Neurofilament light (NF-L) has been introduced as a marker of neuroaxonal injury in neuroinflammatory/-degenerative diseases. In this study we determined the predictive power of serum (s-) and cerebrospinal fluid (CSF-) NF-L levels towards outcome, and explored their potential correlation to diffuse axonal injury (DAI). A total of 182 patients suffering from TBI admitted to the neurointensive care unit at a level 1 trauma center were included. S-NF-L levels were acquired, together with S100B and neuron-specific enolase (NSE). CSF-NF-L was measured in a subcohort (n = 84) with ventriculostomies. Clinical and neuro-radiological parameters, including computerized tomography (CT) and magnetic resonance imaging, were included in the analyses. Outcome was assessed 6 to 12 months after injury using the Glasgow Outcome Score (1-5). In univariate proportional odds analyses mean s-NF-L, -S100B and -NSE levels presented a pseudo-R2 Nagelkerke of 0.062, 0.214 and 0.074 in correlation to outcome, respectively. In a multivariate analysis, in addition to a model including core parameters (pseudo-R2 0.33 towards outcome; Age, Glasgow Coma Scale, pupil response, Stockholm CT score, abbreviated injury severity score, S100B), S-NF-L yielded an extra 0.023 pseudo-R2 and a significantly better model (p = 0.006) No correlation between DAI or CT assessed-intracranial damage and NF-L was found. Our study thus demonstrates that S-NF-L correlates to TBI outcome, even if used in models with S100B, indicating an independent contribution to the prediction, perhaps by reflecting different pathophysiological processes, not possible to monitor using conventional neuroradiology. Although we did not find a predictive value of NF-L for DAI, this cannot be completely excluded. We suggest further studies, with volume quantification of axonal injury, and a prolonged sampling time, in order to better determine the connection between NF-L and DAI.

Assessment of the partitioning capacity of high abundant proteins in human cerebrospinal fluid using affinity and immunoaffinity subtraction spin columns.

The performance of three different affinity and immunoaffinity subtraction spin columns was investigated for the removal of the most abundant proteins in human cerebrospinal fluid (CSF). A pool of human CSF was processed with the spin columns and both the bound and flow through fractions were compared with each other and with intact CSF using 1D gel electrophoresis and nanoLC-MALDI-TOF/TOF-MS analysis. MASCOT MS/MS ionscores were compared before and after processing with the columns. The non-specific co-removal of proteins bound to the high abundant proteins, so called "sponge effect" was also examined for each spin column. The reproducibility of one of the spin columns, ProteomeLab IgY-12 proteome partitioning spin column, was further investigated by isobaric tags for relative and absolute quantification (iTRAQ) labeling and MS/MS analysis. Overall, 173 unique proteins were identified on a 95% MudPIT confidence scoring level. For all three spin columns, the number of proteins identified and their MASCOT scores were increased up to 10 times. The largest degree of non-specific protein removal was observed for a purely affinity based albumin removal column, where 28 other proteins also were present. The ProteomeLab IgY-12 proteome partitioning spin column showed very high reproducibility when combined with iTRAQ labeling and MS/MS analysis. The combined relative standard deviation (R.S.D.) for the high abundant protein removal, iTRAQ labeling and nanoLC-MALDI-TOF/TOF-MS analysis was less than 17.5%.

Assessment of a pyrogallol red technique for total protein measurement in the cerebrospinal fluid of dogs.

The measurement of protein concentration in the cerebrospinal fluid is a basic analytical method in neurology. In this study, a pyrogallol red technique using a human albumin calibrator previously validated in human medicine was tested for canine samples, and the results were compared with those obtained using urine test strips. Pyrogallol red significantly (P<0.05) but moderately underestimated purified dog albumin and globulins. The imprecision of the technique was low: intra- and between-series coefficients of variation were 1.6 and 4.3 per cent at protein concentrations of about 0.3 g/litre. Over 49 samples, there was good agreement between the pyrogallol red and test strip results (r=0.63), especially for low and high protein concentrations, but misclassifications were observed with '+' test strip readings.

Assessment of central nervous system involvement in gambiense trypanosomiasis: value of the cerebro-spinal white cell count.

OBJECTIVE: To assess, in a clinical setting, the comparative values of conventional criteria used in the diagnosis of central nervous system (CNS) involvement in Trypanosoma brucei gambiense sleeping sickness: white cell count (WCC) in cerebrospinal fluid (CSF) > 5 x 10(6) cells/l; total protein concentration in CSF > 40 mg/100 ml); evidence of trypanosomes in CSF following double centrifugation (DC). METHOD: In vitro culture of CSF was used as the gold standard. RESULTS: The study showed that WCC is, by itself, as sensitive for the diagnosis of the CNS involvement as the usually recommended combination of three conventional criteria. The specificity of WCC is improved while the sensitivity is reduced when the cut-off point is set at a higher value (WCC > 10 X 10(6)/l). CONCLUSION: In poorly equipped laboratories, the diagnosis of CNS involvement in patients with confirmed systemic infection should be based only on the WCC. However, a pilot study is needed to assess the feasibility and reliability of the WCC handled by 'front line' personnel, for different cut-off values.

Assessment of amyloid beta protein in cerebrospinal fluid as an aid in the diagnosis of Alzheimer's disease.

The principal constituent of amyloid plaques found in the brains of individuals with Alzheimer's disease (AD) is a 39-42-amino-acid protein, amyloid beta protein (A beta). This study examined whether the measurement of A beta levels in CSF has diagnostic value. There were 108 subjects enrolled in this prospective study: AD (n = 39), non-AD controls (dementing diseases/syndromes; n = 20), and other (n = 49). CSF was obtained by lumbar puncture, and A beta concentrations were determined using a dual monoclonal antibody immunoradiometric sandwich assay. The mean A beta value for the AD group (15.9 +/- 6.8 ng/ml) was not significantly different from that for the non-AD control group (13.0 +/- 7.1 ng/ml; p = 0.07), and substantial overlap in results were observed. A beta values did not correlate with age (r = -0.05, p = 0.59), severity of cognitive impairment (r = 0.22, p = 0.21), or duration of AD symptoms (r = 0.14, p = 0.45). These findings are in conflict with other reports in the literature; discrepant results could be due to the instability of A beta in CSF. A beta immunoreactivity decays rapidly under certain conditions, particularly multiple freeze/thaw cycles. Use of a stabilizing sample treatment buffer at the time of lumbar puncture allows storage of CSF without loss of A beta reactivity. In conclusion, the total CSF A beta level is not a useful marker for current diagnosis of AD.

External quality assessment in clinical neurochemistry: survey of analysis for cerebrospinal fluid (CSF) proteins based on CSF/serum quotients.

Participants (230) from Germany and 20 laboratories in 11 European countries took part in a newly designed cerebrospinal fluid (CSF) survey distributed by INSTAND. Conventional proficiency testing for albumin, IgG, IgA, and IgM in CSF and serum, for total protein in CSF, and for oligoclonal IgG in CSF and serum was combined with evaluation and interpretation of CSF/serum quotients in quotient diagrams. The correct detection of a blood-CSF barrier dysfunction and the pattern of intrathecal immunoglobulin synthesis was judged. The accuracy of CSF/serum quotients and their clinically relevant interpretation was given first priority as a new concept in quality assessment. The main result of the surveys was to confirm that CSF/serum quotients of proteins represent method-independent values approaching the quality of reference values. This finding has consequences for internal quality control of CSF analysis and for accreditation bodies. The sensitivity of the methods for quantifying IgA and IgM in CSF and for detecting oligoclonal IgG fractions is discussed.

[Diagnostic assessment of cerebrospinal fluid protein in brain and spinal tumors]. / Liquoreiweissdiagnostik bei Hirn- und Spinaltumoren.

The cerebrospinal fluid of 69 patients with tumors of the brain and the spine was examined for total protein content, IgG concentration, IgG total protein quotient, and electrophoretic protein pattern. There is no specific finding in the case of the central nervous system. At best characteristic constellations may be established.

[Assessment of prealbumin in cerebrospinal fluid]. / Bewertung des Präalbumins im Liquor cerebrospinalis.

The paper describes statistical relationship between prealbumin and total protein in lumbal CSF of a control group and a total group of patients with neurological diseases. The equations of the regression lines and the boundary lines of the distribution areas did not significantly differ between both groups. Therefore, prealbumin seems to be not qualified for differential diagnosis. On the other hand, its application to characterize functional states of blood-brain-CSF barrier systems is discussed.

The role of lumbar puncture in the evaluation of dementia: the University of Pittsburgh Study.

In a retrospective study of 80 patients over 55 years old, the efficacy of lumbar puncture in evaluating elderly demented patients was examined. Despite a cost of $381 per procedure, in addition to cerebrospinal fluid (CSF) evaluation, no diagnosis was made on the basis of the information obtained in any of the patients (53 per cent) who underwent lumbar puncture. The only abnormalities found were 11 cases of nonspecific elevations in CSF protein and one case of abnormal cellularity not related to bacterial infection. An additional 422 cases of dementia from other series were reviewed, and only four patients were found whose diagnosis could have been made by lumbar puncture--one patient had neurosyphilis, and the other three were postencephalitic. In addition, the literature on complications of lumbar puncture was reviewed. There were no serious complications of lumbar puncture in the present study. The authors concluded that although it is low-risk, lumbar puncture cannot currently be recommended for routine use in the evaluation of elderly demented patients, but should be used in evaluating demented patients under 55 years of age, patients with rapid onset or progression of dementia, patients with syphilis serology in suspected cases of viral encephalitis, and patients with signs and symptoms of fungal meningitis.

Overutilization of cultures of CSF for mycobacteria.

Over a five-year period, 1,883 specimens were cultured for mycobacterium tuberculosis (TB) at our hospital. All cultures were negative, and no cases of tuberculous meningitis were diagnosed. Culture rates (percent of CSF specimens cultured for TB) varied from 74% on the Medicine and Neurology services to 6% on the Pediatric service. These culture rates have been stable for five years. These data suggest that on the Medicine and Neurology services, TB cultures of CSF are persistently overutilized. A simple rule of not culturing CSF for TB if results of the CSF analysis are normal (ie, WBC count less than or equal to 4/cu mm, protein level less than or equal to 45 mg/dL, and glucose level greater than or equal to 45 mg/dL) could reduce utilization by at least 50% without adversely affecting quality of care.

[An economical modification of radial immunodiffusion for the determination of immunoglobulins in the cerebrospinal fluid]. / Eine ökonomische Modifikation der radialen Immundiffusion zur Bestimmung von Immunglobulinen im Liquor cerebrospinalis.

In a total of fifty cerebrospinal fluids, such immunoglobulins as IgG, IgA, and IgM were quantitatively determined in a parallel manner on LC partigen plates and on slides (SEVAC set of means of testing). The comparability of the two methods of test proved excellent with good precision. The sensitivity of IgA determination on slides was made higher, the measurability of all precipitates was improved, and the economic advantage increased by cutting the cost of one determination fifteen times.