Clinical reporting following the quantification of cerebrospinal fluid biomarkers in Alzheimer's disease: An international overview.

INTRODUCTION: The current practice of quantifying cerebrospinal fluid (CSF) biomarkers as an aid in the diagnosis of Alzheimer's disease (AD) varies from center to center. For a same biochemical profile, interpretation and reporting of results may differ, which can lead to misunderstandings and raises questions about the commutability of tests. METHODS: We obtained a description of (pre-)analytical protocols and sample reports from 40 centers worldwide. A consensus approach allowed us to propose harmonized comments corresponding to the different CSF biomarker profiles observed in patients. RESULTS: The (pre-)analytical procedures were similar between centers. There was considerable heterogeneity in cutoff definitions and report comments. We therefore identified and selected by consensus the most accurate and informative comments regarding the interpretation of CSF biomarkers in the context of AD diagnosis. DISCUSSION: This is the first time that harmonized reports are proposed across worldwide specialized laboratories involved in the biochemical diagnosis of AD.

Epidemiology of neuronal surface antibody-mediated autoimmune encephalitis and antibody-based diagnostics.

Epidemiologic data on neuronal surface antibody (NSAb)-associated autoimmune encephalitides (NSAE) are scarce and heterogeneous. We review our 13-year-long biobank-data collection and provide the incidence of NSAE in two Italian provinces (approx. Population of 1,400,000) over a 5-year period (July 2013-June 2018). NSAbs were diagnosed in 75 out of 1179 tested patients (6.4%). The most common NSAbs were anti-LGI1 (30 cases), followed by NMDAR (24). Eleven cases of NSAE were diagnosed in Treviso and Trento provinces with an estimated incidence of 1.54 per 1,000,000 population (LGI1-encephalitis 0.84; C.I. 0.38-1.88). LGI1-E is the most frequent NSAE among adults.

Ratio Aß1-42:p-Tau: a Possible Diagnostic Tool in Differentiating Dementias.

BACKGROUND: Patients with Alzheimer's disease (AD) present a typical biochemical profile of biomarkers: low concentration of ß amyloid 1-42 (Aß1-42), high concentration of total Tau (t-Tau) and phosphorylated Tau at threonine 181 (p-Tau). Several neurodegenerative diseases may overlap with AD, both in regards to clinical symptoms and neuropathology. Many data suggest that Alzheimer's disease (AD) pathophysiology can be identified using biomarkers. It has been hypothesized that subjects with dementia due to AD showed low levels of Aß1-42 combined with the highest levels of total Tau and phosphorylated Tau; moreover, it has been hypothesized that the ratio Aß1-42:p-Tau further help in discriminating Alzheimer's disease from other diagnoses. The aim of this work is to verify this hypothesis in our cohort of patients and to investigate if the same ratio could be a sensitive index able to discriminate MCI due to neurodegenerative factors (MCId) from MCI due to vascular factors (MCIv). METHODS: Two hundred sixty-two patients meeting the NIA-AA and NINDS-AIREN criteria were diagnosed as follow: AD in 120 patients [mean age 71.6 (42 - 87)], FTD in 23 patients [mean age 67.3 (46 - 78)], LBD in 17 patients [mean age 73.2 (58 - 83)], VAD in 9 patients [mean age 71.2 (60 - 81)]. According to the criteria proposed by Petersen RC, 24 patients had the diagnosis of MCId [mean age 71.8 (59 - 81)], 38 MCIv [mean age 69.3 (55-82). The comparison between the ratio of Aß1-42/p-Tau among the six groups was done using t-test for independent samples. A p-value < 0.05 was considered to represent statistical significance. The ROC (Receiver Operating Characteristic) curve analysis was made using R-studio software. RESULTS: The ratio Aß1-42:p-Tau was significantly lower in AD and MCId with respect to all the other groups and the difference was also statistically significant between MCId and MCIv. CONCLUSIONS: Aß1-42:p-Tau ratio has potential for being implemented in the clinical routine for differential diagnosis between AD and other dementias and to distinguish underling pathology such as neurodegenerative or vascular disease.

A Liquid Chromatography-Mass Spectrometry Assay for Determination of Perampanel and Concomitant Antiepileptic Drugs in the Plasma of Patients With Epilepsy Compared With a Fluorescent HPLC Assay.

BACKGROUND: Perampanel is a novel noncompetitive selective antagonist at the postsynaptic ionotropic alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) glutamate receptor, which is approved as an adjunctive agent for the treatment of partial-onset seizure with or without secondary generalization and for primary generalized tonic-clonic seizure in patients with epilepsy who are at least 12 years of age. Limited information is available about the clinical utility of therapeutic drug monitoring of perampanel and therapeutic ranges are so far not established. Therefore, perampanel titration should be performed especially in case of insufficient success of the drug. METHODS: The authors developed a selective and sensitive LC-MS/MS (liquid chromatography-mass spectrometry) assay to monitor perampanel concentrations in plasma, which was compared to a commercially available high-performance liquid chromatography kit with fluorescent detection. Perampanel and the internal standard were extracted from plasma samples by a simple protein precipitation. The method allows the simultaneous quantification of perampanel and several other antiepileptic drugs (AEDs). RESULTS: Data were evaluated according to EMA guidelines for bioanalytical method validation. Extraction recovery of perampanel from human plasma was consistently above 98%. No matrix effect was found. Analytical interferences by other AEDs were not observed. The method was linear in the range from 2.5 to 2800 ng/mL. Intra-assay and interassay reproducibility analyses demonstrated accuracy and precision within acceptance criteria. Data collected from 95 patients, given perampanel as their maintenance antiepileptic therapy, showed a very strong correlation between the 2 methods. CONCLUSIONS: The assay allows for highly sensitive and selective quantification of perampanel and concomitant AEDs in patient plasma samples and can be easily implemented in clinical settings. Our findings are in agreement with previously published data in patients comedicated with enzyme inducer AEDs, but seem to indicate a possible interaction in patients treated with the enzyme inhibitor drug valproic acid.

Diagnostics of paraneoplastic neurological syndromes.

This document presents the guidelines for onconeural antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on paraneoplastic neurological syndromes, indications and limits of onconeural antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists.

Diagnostics of dysimmune peripheral neuropathies.

This document presents the guidelines for anti-ganglioside antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Main clinical information on dysimmune peripheral neuropathies, indications and limits of anti-ganglioside antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists.

Diagnostics of autoimmune encephalitis associated with antibodies against neuronal surface antigens.

This document presents the guidelines for testing antibodies against neuronal surface antigens that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on autoimmune encephalitis associated with antibodies against neuronal surface antigens, indications and limits of testing for such antibodies, instructions for result interpretation, and an agreed laboratory protocol (Appendix A) are reported for the communicative community of neurologists and clinical pathologists.

Diagnostics of the neuromyelitis optica spectrum disorders (NMOSD).

This document presents the guidelines for anti-aquaporin-4 (AQP4) antibody testing that has been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of the sponsoring Italian Association of Neuroimmunology (AINI) congresses. Essential clinical information on neuromyelitis optica spectrum disorders, indications and limits of anti-AQP4 antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists.

Diagnostics of anti-MAG antibody polyneuropathy.

This document presents the guidelines for anti-myelin-associated glycoprotein (MAG) antibody testing that have been developed following a consensus process built on questionnaire-based surveys, internet contacts, and discussions at workshops of sponsoring Italian Association of Neuroimmunology (AINI) congresses. The main clinical information on anti-MAG antibody polyneuropathy, indications and limits of anti-MAG antibody testing, instructions for result interpretation, and an agreed laboratory protocol (Appendix) are reported for the communicative community of neurologists and clinical pathologists.

Tryptamine levels are low in plasma of chronic migraine and chronic tension-type headache.

The primary aim of this study (TA-CH, Tryptophan Amine in Chronic Headache) was to investigate a possible role of tryptophan (TRP) metabolism in chronic migraine (CM) and chronic tension-type headache (CTTH). It is not known if TRP metabolism plays any role in CM and/or CTTH. Plasma levels of serotonin (5-HT), 5-hydroxyindolacetic acid (5-HIAA), metabolite of 5-HT, and tryptamine (TRY) were tested in 73 patients with CM, 15 patients with CTTH and 37 control subjects. Of these, plasmatic TRY was significantly lower in CM (p < 0.001) and in CTTH (p < 0.002) patients with respect to control subjects, while 5-HIAA levels in plasma were within the same range in all groups. 5-HT was undetectable in the plasma of almost all subjects. Our results support the hypothesis that TRP metabolism is altered in CM and CTTH patients, leading to a reduction in plasma TRY. As TRY modulates the function of pain matrix serotonergic system, this may affect modulation of incoming nociceptive inputs from the trigeminal endings and posterior horns of the spinal cord. We suggest that these biochemical abnormalities play a role in the chronicity of CM and CTTH.

Therapeutic drug monitoring of topiramate with a new HPLC method, SPE extraction and high sensitivity pre-column fluorescent derivatization.

BACKGROUND: Topiramate is a 2nd generation antiepileptic drug (AED) recently approved by the FDA for migraine prophylaxis. Its pharmacological activity already appears significant at low doses. Unfortunately, the difficulty in determining the drug in serum at low concentrations hampers the completion of accurate pharmacokinetic studies in humans. Only chromatographic methods allow reaching the necessary sensitivities. METHODS: Almost all of the HPLC methods proposed were based on the preliminary extraction of topiramate from the sample using organic solvents. In our study, the conditions for purifying topiramate through solid-liquid technique in disposable cartridges (SPE) packed with C18 reversed phase were examinated and optimised. After a pre-column derivatization step with 9-fluorenylmethyl chloroformate (FMOC-Cl) and internal standard addition, topiramate was analysed on a CN column with sodium phosphate buffer 50 mmol/L (pH 2.5) containing acetonitrile (60:40, v/v) as the mobile phase. The column effluent was monitored with a fluorescence detector (excitation and emission 1 260 and 315 nm, respectively). 122 samples from our routine laboratory work were analysed in order to confirm the existence of a relationship between topiramate dose and serum concentration and to evaluate the effect of concomitant therapies with enzyme-inducing AEDs. RESULTS: Sensitivity (2 ng/mL), precision (CV within assay of 3.8% and between assays of 6.6%), linearity and accuracy of the method were better than other analytical procedures previously reported. Serum topiramate levels in the group with enzyme-inducing AEDs showed a reduction with respect to the group with non-enzyme-inducing AEDs and the correlation between doses and mean serum concentration gives a linear trend (r2 = 0.916). CONCLUSIONS: The efficacy of SPE extraction together with the method's reliability proved very advantageous for pharmacokinetics studies and, in principle, for therapeutic drug monitoring and toxicological investigations.

Analysis of combined CSF biomarkers in AD diagnosis.

BACKGROUND: The new proposed diagnostic criteria for early diagnosis of Alzheimer's Disease (AD) underline the value of cerebrospinal fluid (CSF) biomarkers. The first aim of the study was to determine the diagnostic accuracy of CSF biomarker Abeta1-42, T-tau, and P-tau in differentiating AD patients in our cohort by means of "pure" biomarkers and in form of a combined analysis of these biomarkers. The second aim of the study was to determine the diagnostic accuracy of these markers for predicting incipient AD in patients with mild cognitive impairment (MCI). METHODS: We studied 102 CSF samples: 33 AD [mean age at baseline 71.2 (54-86)], 16 MCI [mean age at baseline 71.3 (57-78)], 24 non AD dementia, including 7 vascular dementia, 4 frontotemporal degeneration, 5 dementia with Lewy Body, and 8 with other dementia [mean age at baseline 72.7 (51-87)] and 32 non-demented neurological patients [mean age at baseline 71.3 (45-87) referred to as control (CO) later in the text]. A double sandwich ELISA (Innotest beta amyloid Abeta1-42, hTau and P-tau181 by Innogenetics, Gent, Belgium) was performed to quantify the concentration of the above biomarkers. The three biomarkers were then combined in the IATI index [(measured Ab1-42)/(240 + 1.18 *measured tau)], and in the ratios Abeta1-42/T-tau, Abeta1-42/P-tau, T-tau/Abeta1-42 and P-tau/Abeta1-42. RESULTS: Abeta1-42, T-tau and P-tau181 concentration showed statistically significant differences between AD and CO (327.2 pg/mL +/- 150.2 pg/mL and 659.4 pg/mL +/- 254.2 pg/mL; 508.2 pg/mL +/- 360.2 pg/mL and 305.3 pg/mL +/- 228.9 pg/mL; 82.2 pg/mL +/- 26.1 pg/mL and 45.3 pg/mL +/- 26.4 pg/mL, respectively, p < 0.05), while the difference between AD and MCI was statistically different only for Abeta1-42 (327.2 pg/mL +/- 150.2 pg/mL and 600.8 +/- 271.9 pg/mL, respectively, p < 0.05). The IATI index was 0.5 +/- 0.3 in AD, 0.9 +/- 0.6 in MCI, 1.37 +/- 0.9 in non AD dementia and 1.26 +/- 0.8 in non-demented neurological patients. With a cut-off fixed at 1 the sensitivity and specificity of the IATI index in discriminating AD from CO was 84% and 52%, respectively. CONCLUSIONS: This study confirms the great significance of CSF biomarker measurements in AD diagnosis in clinical routine. It is understood that a clinical diagnostic work-up is necessary in the process. Moreover, a biochemical profile of CSF biomarkers requires further investigations.

The role of tyrosine metabolism in the pathogenesis of chronic migraine.

OBJECTIVE: The pathogenesis of chronic migraine (CM) remains largely unknown. We hypothesized that anomalies of tyrosine metabolism, found in migraine without aura (MwwA) patients, play an important role in the transformation of MwwA into CM, since the increase in the number of MwwA attacks is the most predisposing factor for the occurrence of CM. METHODS: To test our hypothesis we measured the plasma levels of dopamine (DA), noradrenaline (NE) and trace amines, including tyramine (TYR) and octopamine (OCT), in a group of 73 patients with CM, 13 patients with chronic tension-type headache (CTTH) and 37 controls followed in the Headache Centers of the Neurology Departments of Asti, Milan and Vicenza hospitals in Italy. RESULTS: The plasma levels of DA and NE were several-fold higher in CM patients compared with control subjects ( P > 0.001). The plasma levels of TYR were also extremely elevated ( P > 0.001); furthermore, these levels progressively increased with the duration of the CM. CONCLUSIONS: Our data support the hypothesis that altered tyrosine metabolism plays an important role in the pathogenesis of CM. The high plasma levels of TYR, a potent agonist of the trace amine associated receptors type 1 (TAAR1), may ultimately down-regulate this receptor because of loss of inhibitory presynaptic regulation, therein resulting in uncontrolled neurotransmitter release. This may produce functional metabolic consequences in the synaptic clefts of the pain matrix implicated in CM.

Plasma cytokine levels in migraineurs and controls.

BACKGROUND: The vasoactive peptide, calcitonin gene-related peptide (CGRP), is released from primary afferent neurons in the trigemino-vascular circulation during migraine headache. CGRP at physiological concentrations and possibly via stimulation of its selective receptors on T-cells, triggers the secretion of cytokines. Cytokines play an important role in several physiological and pathological settings such as immunology, inflammation, and pain. OBJECTIVE: To investigate plasma levels of pro- and anti-inflammatory cytokines in migraineurs and healthy controls. METHODS: We studied 25 migraine patients, during and outside attacks, and 18 healthy control subjects measuring plasma levels of IL-6, IL-10, tumor necrosis factor alpha (TNFalpha), IL-4, IL-1 beta, and IL-2 using ELISA. RESULTS: Circulating levels of IL-10, TNFalpha, and IL-1 beta during attacks were significantly higher in comparison to their levels outside attacks (P=.0003, P=.03, and P=.05, respectively). IL-10 and TNF serum levels were higher in patients studied soon after headache onset and lower over time (P=.004 and P=.05). CONCLUSION: Our results suggest that TNFalpha, IL-1 beta, and IL-10 may be involved in the pathogenesis of migraine attacks.

Protective effect of urate oxidase on uric acid induced-monocyte apoptosis.

Uremic patients have a higher risk of infection and malignancy than normal subjects. Previous studies have deomonstrated that monocytes isolated from uremic patients display an increased apoptosis rate compared to normal subjects; furthermore uremic plasma can increase apoptosis rates on U937, a human monocytic cell line. In several pathological conditions, precipitation of uric acid crystals can lead to renal insufficiency or acute renal failure by different mechanisms. In recent studies uric acid has been shown to induce inflammatory response from monocytes and it has been suggested to be involved in cell dysfunction. Rasburicase is a new recombinant urate oxidase developed to prevent and treat hyperuricaemia in patients with cancer or renal failure; it degrades uric acid to allantoin, a less toxic and more soluble product. In the present study, we aimed at determining whether uric acid may be a factor affecting U937 apoptosis, and whether urate oxidase may reduces or even prevent uric acid induced cell apoptosis. Hoechst staining and internucleosome ledder fragmentation of DNA showed that uric acid increased the percentage of apoptotic cells comparing to the control and that when the U937 cells were incubated with uric acid and urate oxidase the percentage of apoptosis significantly decreased (from 43+/-7% to 19+/- 3%, p<0.05). Also, the activity of caspase-8 and caspase-3 showed the same trend (caspase 3: from 2.7+/-0.53 to 1.6+/-0.42; caspase-8: from 2.2+/-0.43 to 1.3+/-0.57). A reduction of intracellular reduced glutathione (GSH) concentration was found in uric acid treated cells while the addition of urate oxidase in the uric acid incubated cells decreased the GSH extrusion. The concentration of TNF-alpha was increased in the sample incubated with uric acid comparing to the control. Uric acid is an inducer of apoptosis on U937 cell line, and therefore it may be a component of the mosaic of uremic toxins both in acute and chronic renal disease. We can hypothesize that uric acid might be directly involved in the apoptotic process trough the activation of both death receptor and mitochondrial-mediated pathways. We have, also, demonstrated that urate oxidase is able to prevent at least in part, the effect of uric acid on U937 apoptosis. This effect might be a result of different mechanisms of action.

Longitudinal study of apoptosis in chronic uremic patients.

Uremia is associated with a state of immune dysfunction, increasing infection and malignancy rates. Dysregulation of homeostasis may be directly related to abnormal apoptosis regulation, a process which is crucial for the maintenance of the biologic system. Abnormal apoptosis rates (ARs) have been reported in the literature. We performed a longitudinal study over a 10-week period in three groups of uremic subjects-hemodialysis (HD), peritoneal dialysis (PD), and predialysis chronic renal failure (CRF). Our results showed that ARs were consistent over the observed period. Monocytes extracted from HD and CRF subjects had higher ARs compared to PD and controls (HD: 26.06 +/- 8.82; CRF: 26.96 +/- 12.81; PD: 14.77 +/- 5.87; C: 11.42 +/- 4.60) when placed in culture medium. The plasma of HD and CRF subjects when incubated with U937 cells had a stronger apoptogenic potential compared with PD and controls (HD: 26.08 +/- 11.39; CRF: 24.87 +/- 9.07; PD: 12.13 +/- 4.51; C: 11.69 +/- 4.02). Inflammatory markers (C-reactive protein [CRP], procalcitonin) and cytokines (interleukin [IL]-1beta, IL-2, IL-10) had a generally poor correlation except for tumor necrosis factor (TNF)-alpha (p < 0.001). The phagocytic ability of U937 cells when incubated with the various plasma demonstrated impaired response in the HD and CRF subjects (HD: 27.56 +/- 6.67; CRF: 30.24 +/- 9.08; PD: 36.55 +/- 9.80; C: 40.04 +/- 6.98). These results suggest continuous renal purification, such as in continuous ambulatory peritoneal dialysis (CAPD), may have advantages over intermittent therapies in regulating apoptosis and maintaining biologic function and homeostasis.

In vitro removal of therapeutic drugs with a novel adsorbent system.

BACKGROUND/AIMS: Substances in the middle molecular weight range have been shown to play a significant pathogenetic role in as diverse disorders as end-stage renal disease and multiple organ failure. To overcome the limitations in the amount removed by hemofilters, new sorbents with a high biocompatibility are actively being developed. Furthermore, biocompatible sorbents by their nonspecific adsorptive behavior could have great impact on detoxification treatment in exogenous intoxications. We performed an in vitro evaluation of a newly developed highly biocompatible sorbent cartridge (Betasorb((R))), examining its adsorptive capacity concerning therapeutic drugs. METHODS: Uremic blood spiked with a range of therapeutic drugs was recirculated for 2 h in an in vitro hemoperfusion circuit containing a Betasorb device for hemoperfusion. The drug concentrations before and after the passage of the cartridge were measured, and the total amount removed was calculated. RESULTS: The sorbent showed effective removal of glycopeptide antibiotics, digoxin, theophylline, phenobarbital, phenytoin, carbamazepine, and valproic acid. Moderate removal could be demonstrated for tacrolimus and cyclosporine A; aminoglycosides were removed to a small extent only. CONCLUSION: Betasorb hemoperfusion shows a potent adsorptive capacity concerning therapeutic drugs (except aminoglycosides) and could be of major value in the treatment of intoxications. On the other hand, drug monitoring and possible adjustments are necessary during Betasorb hemoperfusion to maintain the therapeutic ranges of the drugs in blood.