Elevation of certain polyols in the cerebrospinal fluid of patients with multiple sclerosis

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.

Assay of myo-inositol in cerebrospinal fluid and plasma by chemical ionization mass spectrometry of the hexaacetate derivative

The paper describes a capillary gas chromatographic/mass spectrometric technique to quantitate myo-inositol in cerebrospinal fluid (CSF) and plasma. A highly abundant fragment ion, m/z 373, for the hexaacetate derivative of myo-inositol was generated by chemical ionization (CI). This ion and the analogous ion of hexadeuterated myo-inositol (the internal standard), m/z 379, were both monitored in the assay. CI was performed with acetonitrile vapor in an ion trap mass spectrometer. Microliter quantities of CSF or plasma were mixed with the internal standard, dried and acetylated. After a post-derivatization clean-up, samples were analyzed on a capillary gas chromatograph interfaced with a Finnigan ion trap. Standard curves constructed for both CSF and plasma were linear and reproducible. Absence of matrix effects and good precision in the results indicate the suitability of the technique for critical assays. Results from the determination of myo-inositol in the CSF and plasma of healthy subjects and those with neurological deficits are reported.

Low blood-to-cerebrospinal fluid passage of sorbitol after intravenous infusion

BACKGROUND AND PURPOSE

Compared with mannitol, the osmotherapeutic agent sorbitol is less prone to accumulate in the blood and the same quantity may be infused in a smaller volume. Because of these advantageous characteristics, we studied the pharmacokinetics of sorbitol in serum and cerebrospinal fluid.

METHODS

Six patients (five women and one man; age range, 46-70 years) with an external ventriculostomy and suffering from brain edema due to cerebrovascular disease received sorbitol as part of their therapy. Before and after the first dose of 50 g infused over 20 minutes, sorbitol concentrations in serum and cerebrospinal fluid were determined repeatedly using an enzymatic procedure.

RESULTS

Maximal sorbitol concentrations ranged from 2,705 to 5,821 (median, 3,227) mg/l in serum compared with 6.7-130.7 (median, 19.5) mg/l in cerebrospinal fluid. Cerebrospinal fluid maxima were observed 0.17-3 hours after the end of the infusion. Sorbitol elimination in serum was adequately described by a two-compartment pharmacokinetic model (distribution half-life, 0.05-0.14 hour; elimination half-life, 0.23-0.61 hour). Elimination in cerebrospinal fluid followed a single-exponential decay and was considerably slower than that in serum (half-life, 1.3-7.7 hours).

CONCLUSIONS

The maximal cerebrospinal fluid concentration/maximal serum concentration ratio was low for sorbitol, thus suggesting a small potential risk of inducing an increase of intracranial pressure after osmotherapy (rebound effect).

Quantitative analysis of polyols in human plasma and cerebrospinal fluid

We used gas chromatography in conjunction with flame ionization detection to quantitate nine polyols and aldo and keto sugars (as silyl derivatives) in human plasma and cerebrospinal fluid (CSF). Rhamnose, not found in CSF or plasma, was used as an internal standard with a lower limit of quantitation of 0.4 mg/l. CSF polyol and sugar concentrations (mean +/- S.D.) in fourteen healthy subjects (age range 27.1-85.9 years) were: anhydroglucitol, 19.9 +/- 5.3 mg/l; arabitol, 4.8 +/- 0.9 mg/l; erythritol, 2.4 +/- 0.5 mg/l; myoinositol, 28.6 +/- 8.3 mg/l; ribitol, 1.6 +/- 0.1 mg/l; fructose, 25.5 +/- 11.1 mg/l; glucose, 587 +/- 70 mg/l; glucitol, 7.7 +/- 1.5 mg/l; and mannose, 10.6 +/- 2.4 mg/l. The respective plasma concentrations were 30.6 +/- 11.5, less than 0.4, 0.4 +/- 0.2, 6.3 +/- 2.6, less than 0.4, 23.4 +/- 21.4, 897 +/- 214, less than 0.4 and 13.7 +/- 6.3 mg/l. Polyol CSF-to-plasma concentration ratios greater than 2 were observed for myoinositol, erythritol, arabitol, glucitol and ribitol, indicative of active accumulation or synthesis of these polyols within the central nervous system.

Isoprenoid biosynthesis in multiple sclerosis, II. A possible role of NADPH

Genetic predisposition in MS, influence of fat consumption on the disease, and excretion of lipid metabolites in urine led us to investigate isoprenoid metabolism in this disease. Ubiquinone concentration and biosynthesis was normal in lymphocytes. Cytochrome oxidase, which contains an isoprenoid side chain, was normal in activity. Cholesterol biosynthesis from acetate was found to be elevated in MS, and so was triglyceride biosynthesis. Increased biosynthesis may offer a very simple explanation to all the metabolites excreted (3-methylglutaconic acid, 2-hydroxy-2-methyl-3-butenoic acid and adipic acid). Increased biosynthesis may be caused by an elevated NADPH/NADP ratio, since such an elevation may also account for many other biochemical anomalies in MS. Elevated NADPH/NADP ratio may be of direct importance in the pathogenesis.

Profiling of carbohydrates, glycoproteins and glycolipids

Current chromatographic methods for the analysis of a variety of carbohydrate materials in body fluids and tissues have been reviewed, from the viewpoints of clean-up of samples, separation modes, methods for detection and quantification, and degree of convenience. This review also contains several tables, listing names of samples, methods of analysis, analytical conditions, and normal as well as pathological levels reported, from representative publications.