Distinct metabolomic signature in cerebrospinal fluid in early parkinson's disease.

OBJECTIVE: The purpose of this study was to profile cerebrospinal fluid (CSF) from early-stage PD patients for disease-related metabolic changes and to determine a robust biomarker signature for early-stage PD diagnosis. METHODS: By applying a non-targeted and mass spectrometry-driven approach, we investigated the CSF metabolome of 44 early-stage sporadic PD patients yet without treatment (DeNoPa cohort). We compared all detected metabolite levels with those measured in CSF of 43 age- and gender-matched healthy controls. After this analysis, we validated the results in an independent PD study cohort (Tübingen cohort). RESULTS: We identified that dehydroascorbic acid levels were significantly lower and fructose, mannose, and threonic acid levels were significantly higher (P < .05) in PD patients when compared with healthy controls. These changes reflect pathological oxidative stress responses, as well as protein glycation/glycosylation reactions in PD. Using a machine learning approach based on logistic regression, we successfully predicted the origin (PD patients vs healthy controls) in a second (n = 18) as well as in a third and completely independent validation set (n = 36). The biomarker signature is composed of the three markers-mannose, threonic acid, and fructose-and allows for sample classification with a sensitivity of 0.790 and a specificity of 0.800. CONCLUSION: We identified PD-specific metabolic changes in CSF that were associated with antioxidative stress response, glycation, and inflammation. Our results disentangle the complexity of the CSF metabolome to unravel metabolome changes related to early-stage PD. The detected biomarkers help understanding PD pathogenesis and can be applied as biomarkers to increase clinical diagnosis accuracy and patient care in early-stage PD. © 2017 International Parkinson and Movement Disorder Society.

Fructose levels are markedly elevated in cerebrospinal fluid compared to plasma in pregnant women.

BACKGROUND: Fructose, unlike glucose, promotes feeding behavior in rodents and its ingestion exerts differential effects in the human brain. However, plasma fructose is typically 1/1000 th of glucose levels and it is unclear to what extent fructose crosses the blood-brain barrier. We investigated whether local endogenous central nervous system (CNS) fructose production from glucose via the polyol pathway (glucose → sorbitol → fructose) contributes to brain exposure to fructose. METHODS: In this observational study, fasting glucose, sorbitol and fructose concentrations were measured using gas-chromatography-liquid mass spectroscopy in cerebrospinal fluid (CSF), maternal plasma, and venous cord blood collected from 25 pregnant women (6 lean, 10 overweight/obese, and 9 T2DM/gestational DM) undergoing spinal anesthesia and elective cesarean section. RESULTS: As expected, CSF glucose was ~ 60% of plasma glucose levels. In contrast, fructose was nearly 20-fold higher in CSF than in plasma (p < 0.001), and CSF sorbitol was ~ 9-times higher than plasma levels (p < 0.001). Moreover, CSF fructose correlated positively with CSF glucose (ρ 0.45, p = 0.02) and sorbitol levels (ρ 0.75, p < 0.001). Cord blood sorbitol was also ~ 7-fold higher than maternal plasma sorbitol levels (p = 0.001). There were no differences in plasma, CSF, and cord blood glucose, fructose, or sorbitol levels between groups. CONCLUSIONS: These data raise the possibility that fructose may be produced endogenously in the human brain and that the effects of fructose in the human brain and placenta may extend beyond its dietary consumption.

Antiepileptic drugs abolish ictal but not interictal epileptiform discharges in vitro.

PURPOSE: We established the effects of the antiepileptic drugs (AEDs) carbamazepine (CBZ), topiramate (TPM), and valproic acid (VPA) on the epileptiform activity induced by 4-aminopyridine (4AP) in the rat entorhinal cortex (EC) in an in vitro brain slice preparation. METHODS: Brain slices were obtained from Sprague-Dawley rats (200-250 g). Field and intracellular recordings were made from the EC during bath application of 4AP (50 microm). AEDs, and in some experiments, picrotoxin were bath applied concomitantly. RESULTS: Prolonged (>3 s), ictal-like epileptiform events were abolished by CBZ (50 microm), TPM (50 microm), and VPA (1 mm), whereas shorter (<3 s) interictal-like discharges continued to occur, even at concentrations up to 4-fold as high. gamma-Aminobutyric acid (GABA)(A)-receptor antagonism changed the 4AP-induced activity into recurrent interictal-like events that were not affected by CBZ or TPM, even at the highest concentrations. To establish whether these findings reflected the temporal features of the epileptiform discharges, we tested CBZ and TPM on 4AP-induced epileptiform activity driven by stimuli delivered at 100-, 10-, and 5-s intervals; these AEDs reduced ictal-like responses to stimuli at 100-s intervals at nearly therapeutic concentrations, but did not influence shorter interictal-like events elicited by stimuli delivered every 10 or 5 s. CONCLUSIONS: We conclude that the AED ability to control epileptiform synchronization in vitro depends mainly on activity-dependent characteristics such as discharge duration. Our data are in keeping with clinical evidence indicating that interictal activity is unaffected by AED levels that are effective to stop seizures.

Relationship of cerebrospinal fluid glucose metabolites to MRI deep white matter hyperintensities and treatment resistance in bipolar disorder patients.

OBJECTIVES: Both diabetes mellitus and magnetic resonance image (MRI) deep white matter hyperintensities (WMHs) are more common in bipolar disorder (BD) patients than in matched controls. Deep-as opposed to periventricular--WMHs and diabetes are associated with treatment resistance and poorer outcome. This study investigated whether brain glucose metabolism by the polyol pathway--a pathway linked to nervous tissue disease in diabetes--is related to deep WMH volume and treatment resistance in BD patients. METHODS: Volumes of fluid-attenuated inversion recovery WMHs were quantified and correlated with cerebrospinal fluid (CSF) concentrations of glucose metabolites in 20 nondiabetic patients with BD and nondiabetic comparison subjects with schizophrenia (n = 15) or transient neurologic symptoms (neurologic controls, n = 15). RESULTS: BD patients, but not schizophrenic patients, had significantly greater volumes of deep but not periventricular WMHs compared to neurologic controls. BD subjects also had significantly greater CSF concentrations of sorbitol and fructose (the polyol pathway metabolites of glucose) compared to controls. Significant positive correlations between CSF metabolites and WMH volumes were found only in the BD group and were between deep WMH volumes and CSF sorbitol (rho = 0.487, p = 0.029) and fructose (rho = 0.474, p = 0.035). An index of treatment resistance correlated significantly with deep WMH volume (rho = 0.578, p = 0.008), sorbitol (rho = 0.542, p = 0.013), and fructose (rho = 0.692, p = 0.001) in BD subjects but not in other subjects. CONCLUSIONS: This is the first reported evidence of relationships between abnormal brain glucose metabolism and both deep WMHs and treatment resistance in a group of BD patients. Further studies are necessary to determine the significance of these findings to BD pathophysiology.

Cerebrospinal fluid evidence of increased extra-mitochondrial glucose metabolism implicates mitochondrial dysfunction in multiple sclerosis disease progression.

In contrast to relapse, the mechanisms of multiple sclerosis (MS) disease progression are less understood and appear not to be exclusively inflammatory in nature. In this pilot study we investigated the relationship between disturbed CNS energy metabolism and MS disease progression. We tested the hypothesis that cerebrospinal fluid (CSF) concentrations of sorbitol, fructose, and lactate, all metabolites of extra-mitochondrial glucose metabolism, would be elevated in secondary progressive (SP) MS patients and would be associated with worsening neurologic disability. We measured metabolite concentrations by gas chromatographic/mass spectrometric and enzymatic methods in archived CSF samples from 85 MS patients [31 relapsing-remitting (RR) and 54 SP patients] and 18 healthy controls. We found that concentrations of all three metabolites, but not concentrations of glucose or myoinositol, were significantly increased in CSF from SP and, to a lesser degree, RR patients, compared to controls. Furthermore, CSF concentrations of sorbitol and fructose (polyol pathway metabolites), but not lactate (anaerobic glycolysis metabolite), correlated positively and significantly with Expanded Disability Status Scale (EDSS) score, an index of neurologic disability in MS patients. We conclude that extra-mitochondrial glucose metabolism is increased in MS patients and is associated with disease progression evidenced by increasing EDSS score. As extra-mitochondrial glucose metabolism increases with impaired mitochondrial metabolism of glucose, these findings implicate mitochondrial dysfunction in the pathogenesis of MS disease progression. CSF metabolic profiling may be useful in clarifying the role of mitochondrial pathology in progression and in targeting and monitoring therapies for disease progression that aim to preserve or boost mitochondrial glucose metabolism.

The plasma pharmacokinetics and cerebral spinal fluid penetration of intravenous topiramate in newborn pigs.

INTRODUCTION: Pre-clinical studies suggest that the anticonvulsant topiramate confers neurologic protection against ischemia. An intravenous formulation of topiramate has been developed for administration during conditions such as hypoxia-ischemia when enteral absorption may be unpredictable. The plasma pharmacokinetics, cerebrospinal fluid (CSF) penetration and pharmacodynamics of intravenous topiramate were studied in an established piglet model of hypoxia-ischemia. METHODS: The plasma pharmacokinetics of topiramate were studied in a group of chronically instrumented conscious piglets (n = 8), and in a group of piglets following an episode of hypoxia-ischemia (n = 8). These groups were divided into equal dose cohorts in which two doses of intravenously administered topiramate, 5 and 40 mg/kg, were studied. The animals' heart rate, arterial pressure and EEG were monitored. Plasma for topiramate concentration was sampled for up to 26 h. A single CSF topiramate concentration was determined 1 h following drug administration. Topiramate was quantified using a specific LC/MS assay. RESULTS: The animals tolerated intravenous topiramate well, with no significant changes in physiologic and neurologic parameters. Plasma topiramate concentrations following an intravenous dose were best described by a bi-exponential equation, with a mean clearance of 39+/-18 ml/h/kg, and a terminal half-life of 14.3 (range 7.5-48.1) h. A dose of 5 mg/kg was sufficient to maintain plasma drug concentrations greater than 10 micro M for 24 h. CSF topiramate concentration at 1 h was 12+/-1 micro M and 109+/-26 micro M at the 5 and 40 mg/kg doses, respectively. CONCLUSION: Topiramate administered intravenously was well tolerated. Slow clearance of the drug allowed for maintenance of potential neuroprotective concentrations following a single dose of drug for 24 h. High drug penetration into the CSF is an ideal pharmacologic characteristic of any potential neuroprotective agent. The pharmacokinetic profile of intravenously administered topiramate, including its penetration into the CSF, appears to achieve this goal.

Liquid chromatography tandem mass spectrometry assay for topiramate analysis in plasma and cerebrospinal fluid: validation and comparison with fluorescence-polarization immunoassay.

SUMMARY: The authors report the development and validation of a liquid chromatography tandem mass spectrometry assay (LC/MS/MS assay) for the analysis of topiramate (2,3:4,5-bis-o-(-1-methyl)-beta-D-fructopyranose sulfamate) in plasma and cerebrospinal fluid (CSF). Comparison is made with the commercially available fluorescence-polarization immunoassay (FPIA). LC/MS/MS ASSAY: Using the internal standard, 1,2:3,4-bis-o-(1-methylethylidene-alpha-D-galactopyranose sulfamate), a structural isomer, the calibration curve in plasma was linear in the concentration range of 0.02-20.0 mg/L (r(2) = 0.9998). The coefficients of variation in plasma were < or = 3%, and the accuracy ranged from 100% to 101% in the therapeutically relevant concentration range of 0.4-16.0 mg/L. In CSF, the mean recovery was 98%, and there was linearity between the nominal and the estimated concentration in the range of 1.5-20.0 mg/L (r(2)= 0.9996). FPIA: The calibration curve was linear in the concentration interval of 1.6-24.3 mg/L (r(2) = 0.9994), and the mean recovery was 96%. Accuracy in plasma was 99- 104%, and precision was 3.2-6.0%. In CSF, there was linearity between the nominal concentration and the estimated concentration in the range of 1.5-20.0 mg/L (r(2) = 0.9995), and the mean recovery was 100%. COMPARISON BETWEEN FPIA AND LC/MS/MS: There was a high correlation between the FPIA and the LC/MS/MS assay (r(2) = 0.9965 in plasma and r(2) = 0.9996 in CSF, P < 0.001 for both). In plasma and CSF, the two methods showed equal results, evaluated as the ratio between the two methods (plasma: median ratio = 1.00; 95% confidence interval [CI], 0.98-1.02, paired-sample test, P = 0.79; and CSF: median ratio = 1.00, 95% CI, 0.99-1.02, paired-sample test, P = 0.75). The coefficient of variation on the ratios between the two methods had similar levels: 5% in plasma and 3% in CSF. CONCLUSION: The new LC/MS/MS assay has favorable characteristics, being highly precise and accurate. FPIA also proved precise and accurate, and there was a high agreement with the LC/MS/MS assay in plasma and CSF. Either method displayed sufficient precision and accuracy and may thus be implemented in daily routine.

Plasma concentration of topiramate correlates with cerebrospinal fluid concentration.

The authors examined the ratio between the plasma and the cerebrospinal fluid (CSF) concentration of topiramate in 14 adults with epilepsy. Simultaneous trough samples of venous blood and CSF were collected and analyzed as total and unbound concentrations. Concomitant levels were also analyzed of lamotrigine (n = 5) and the relevant oxcarbazepine metabolite, 10-hydroxycarbazepine (n = 3). There was a close correlation between the plasma and the CSF concentration for both the total and unbound concentration of topiramate. The median CSF/plasma ratio of total topiramate was 0.85. The free topiramate concentration in plasma was not different from the free topiramate concentration in CSF. The CSF/plasma ratios showed little variation and were independent of the plasma level for both the total and the unbound levels. The unbound fraction of topiramate was 84% in plasma and 97% in CSF. The CSF concentrations of lamotrigine and 10-hydroxycarbazepine were 50% and 61% of the plasma concentrations, respectively. For topiramate, there is a close correlation between the plasma concentration and the CSF concentration. There does not seem to be a saturable carrier mechanism restricting topiramate transport across the blood-brain barrier. The concentration of topiramate in CSF is equal to the unbound proportion of topiramate in plasma, implying that the delivery of topiramate to the brain occurs via transfer from the unbound plasma pool. Plasma is thus a relevant matrix for therapeutic drug monitoring of topiramate.

Estimation of topiramate in subdural cerebrospinal fluid, subcutaneous extracellular fluid, and plasma: a single case microdialysis study.

PURPOSE: To estimate topiramate (TPM) concentrations in subdural cerebrospinal fluid (CSF), subcutaneous extracellular fluid (ECF), and plasma and to study the correlation of TPM concentrations in these three different compartments. METHODS: In this single case study of a patient with drug-resistant partial epilepsy undergoing presurgical evaluation with subdural EEG monitoring, we used microdialysis to estimate concentrations of unbound TPM in CSF of the subdural space and ECF of abdominal subcutaneous tissue. Blood samples were drawn for estimation of TPM concentrations in plasma. RESULTS: The correlation between unbound TPM concentrations in subdural CSF and abdominal subcutaneous ECF was good. The mean ratio of ECF/CSF TPM concentration was 0.93 (SD+/-0.03) and the correlation coefficient was 0.98. The mean ratio of ECF/total plasma TPM was 0.75 (SD+/-0.06), and the correlation coefficient was 0.99. The mean ratio of CSF/total plasma TPM was 0.81 (SD+/-0.06), and the correlation coefficient was 0.97. CONCLUSIONS: Assuming a protein binding of TPM of approximately 13%. it is concluded that, based on nine microdialysis samples from a single subject, TPM levels in the CSF at the cortical surface are approximately the same as the unbound plasma levels. Additional patients should be studied to confirm the results.

[A new method for the determination of sugars in cerebrospinal fluid (author's transl)]. / Neue Ergebnisse der Zuckeranalytik von Liquor cerebrospinalis.

The determination of fructose, galactose, glucose, mannose, rhamnose and ribose, using a newly developed liquid chromatography sugar analyzer is reported. High sensitivity (detection limit: 0.05 to 0.23 microgram per compound), resolution and specifity of the method permits the routine detection of carbohydrates in biological fluids without prior extraction and enrichment. The procedure opens new possibilities in medicinal diagnosis.