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Brain metabolism perturbation can contribute to traits and diseases. We conducted a genome-wide association study for cerebrospinal fluid (CSF) and brain metabolite levels, identifying 205 independent associations (47.3% new signals, containing 11 new loci) for 139 CSF metabolites, and 32 independent associations (43.8% new signals, containing 4 new loci) for 31 brain metabolites. Of these, 96.9% (CSF) and 71.4% (brain) of the new signals belonged to previously analyzed metabolites in blood or urine. We integrated the metabolite quantitative trait loci (MQTLs) with 23 neurological, psychiatric and common human traits and diseases through colocalization to identify metabolites and biological processes implicated in these phenotypes. Combining CSF and brain, we identified 71 metabolite-trait associations, such as glycerophosphocholines with Alzheimer's disease, O-sulfo-L-tyrosine with Parkinson's disease, glycine, xanthine with waist-to-hip ratio and ergothioneine with inflammatory bowel disease. Our study expanded the knowledge of MQTLs in the central nervous system, providing insights into human traits., Competing Interests: Competing interests: C.C. has received research support from GSK and EISAI and is a member of the advisory board of Circular Genomics and owns stocks. A.R. and M.B. have received research support from Grifols, Roche, Araclon and Janssen. The funders of the study had no role in the collection, analysis or interpretation of data; in the writing of the report; or in the decision to submit the paper for publication. All other authors have no conflict of interest., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Concurrent measurement of tyrosine, tryptophan and their metabolites, and other co-factors could help to diagnose and better understand a wide range of metabolic and neurological disorders. The two metabolic pathways are closely related to each other through co-factors, regulator molecules and enzymes. By using high performance liquid chromatography coupled to electrospray ionization triple quadrupole mass spectrometry, we present a robust, selective and comprehensive method to determine 30 molecules within 20 min using a Waters Atlantis dC18. The method was validated according to the guideline of European Medicines Agency on bioanalytical method validation. Analytical performance met all the EMA requirements and the assay covered the relevant clinical concentrations. Linear correlation coefficients were all >0.998. Intra-day and inter-day accuracy were between 80-119% and 81-117%, precision 1-19% respectively. The method was applied to measure TYR, TRP and their metabolites, and other neurologically important molecules in human serum and CSF samples. The assay can facilitate the diagnosis and is suitable for determination of reference values in clinical laboratories., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:, (Copyright © 2020. Published by Elsevier B.V.)

Huntington's disease (HD) is a severe neurological disease leading to psychiatric symptoms, motor impairment and cognitive decline. The disease is caused by a CAG expansion in the huntingtin (HTT) gene, but how this translates into the clinical phenotype of HD remains elusive. Using liquid chromatography mass spectrometry, we analyzed the metabolome of cerebrospinal fluid (CSF) from premanifest and manifest HD subjects as well as control subjects. Inter-group differences revealed that the tyrosine metabolism, including tyrosine, thyroxine, L-DOPA and dopamine, was significantly altered in manifest compared with premanifest HD. These metabolites demonstrated moderate to strong associations to measures of disease severity and symptoms. Thyroxine and dopamine also correlated with the five year risk of onset in premanifest HD subjects. The phenylalanine and the purine metabolisms were also significantly altered, but associated less to disease severity. Decreased levels of lumichrome were commonly found in mutated HTT carriers and the levels correlated with the five year risk of disease onset in premanifest carriers. These biochemical findings demonstrates that the CSF metabolome can be used to characterize molecular pathogenesis occurring in HD, which may be essential for future development of novel HD therapies.

Capillary electrophoresis (CE) is a well-established and one of the most powerful separation techniques in the field of chiral separations. Its hyphenation with mass spectrometry (MS) combines both the high separation efficiency and low sample consumption of CE and the high sensitivity and structural information of MS. Thus, the outstanding chiral resolution power of CE along with the MS advantages makes CE-MS a perfect combination to achieve sensitive enantioseparations. This chapter describes three representative examples of different approaches used in the chiral analysis of amino acids in biological fluids by CE-MS. The first methodology uses the partial filling technique to avoid the entry of cyclodextrins in the MS source. The second method shows the possibility to carry out the direct coupling EKC-MS even when a relative high concentration of a native cyclodextrin is used as chiral selector. The last example illustrates an alternative strategy based on the formation of stable diastereomers between an enantiomerically pure chiral reagent and the amino acids enantiomers which can be separated in an achiral environment.

Unlabelled: Low-grade gliomas (LGGs) may harbor malignant foci, which are characterized by increased tumor cellularity and angiogenesis. We used diffusion-weighted MR imaging (apparent diffusion coefficient [ADC]) and PET with the amino acid O-(2-(18)F-fluorethyl)-L-tyrosine ((18)F-FET) to search for focal changes of diffusion (ADC) and amino acid uptake and to investigate whether focal changes in these parameters colocalize within LGGs., Methods: We retrospectively selected 18 patients with nonenhancing LGG. All patients had undergone (18)F-FET PET and MR imaging for preoperative evaluation or for therapy monitoring in recurrent or progressive LGG. Region-of-interest analysis was performed to compare (18)F-FET uptake and ADC values in areas with focal intratumoral maximum metabolic activity and diffusion restriction and between tumor and normal brain. (18)F-FET uptake was normalized to the mean cerebellar uptake (ratio). ADC values were also compared with the (18)F-FET uptake on a voxel-by-voxel basis across the whole tumor., Results: The mean focal maximum (mean ± SD, 1.69 ± 0.85) and global (18)F-FET uptake in tumors (1.14 ± 0.41) exceeded that of normal cortex (0.85 ± 0.09) and cerebrospinal fluid (0.82 ± 0.20). ADC values in the area with most restricted diffusion (1.07 ± 0.22 × 10(-3) mm(2)/s) and in the whole tumor (1.38 ± 0.27 × 10(-3) mm(2)/s) were in the range between normal cortex (0.73 ± 0.06 × 10(-3) mm(2)/s) and cerebrospinal fluid (2.84 ± 0.09 × 10(-3) mm(2)/s). (18)F-FET uptake did not correlate with corresponding (colocalizing) ADC values, either in the area with focal maximum metabolic activity or in the area with most restricted diffusion or in the whole tumor., Conclusion: There is no congruency between (18)F-FET uptake and diffusivity in nonenhancing LGG. Diffusion restriction in these tumors most likely represents changes in brain and tumor cell densities as well as alteration of water distribution and is probably not directly correlated with the density of tumor cells.

Forensic biomarkers are needed in sudden infant death syndrome (SIDS) to help identify this group among other sudden unexpected deaths in infancy. Previously, we reported multiple serotonergic (5-HT) abnormalities in nuclei of the medulla oblongata that help mediate protective responses to homeostatic stressors. As a first step toward their assessment as forensic biomarkers of medullary pathology, here we test the hypothesis that 5-HT-related measures are abnormal in the cerebrospinal fluid (CSF) of SIDS infants compared with those of autopsy controls. Levels of CSF 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), the degradative products of 5-HT and dopamine, respectively, were measured by high-performance liquid chromatography in 52 SIDS and 29 non-SIDS autopsy cases. Tryptophan (Trp) and tyrosine (Tyr), the substrates of 5-HT and dopamine, respectively, were also measured. There were no significant differences in 5-HIAA, Trp, HVA, or Tyr levels between the SIDS and non-SIDS groups. These data preclude the use of 5-HIAA, HVA, Trp, or Tyr measurements as CSF autopsy biomarkers of 5-HT medullary pathology in infants who have died suddenly and unexpectedly. They do, however, provide important information about monoaminergic measurements in human CSF at autopsy and their developmental profile in infancy that is applicable to multiple pediatric disorders beyond SIDS.

Objective: Psychomotor impairment has been described in hypertyrosinemia types II and III (HT III). Only recently cognitive deficits have also been reported in hypertyrosinemia type I (HT I). The pathogenic mechanisms responsible are unknown. Since implementation of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC, Nitisinone (Swedish Orphan International)) in the treatment of HT I, plasma tyrosine elevation is a common finding as known from the other hypertyrosinemias., Patients and Methods: With elevated tyrosine as suspected pathogenic factor in the development of cognitive deficits, we here investigated tyrosine in the cerebrospinal fluid (CSF) and serotonergic and dopaminergic neurotransmitter levels in three patients with HT I during long-term treatment with Nitisinone. In addition, Nitisinone concentrations in plasma and CSF were measured. We also assessed psychomotor and cognitive development by standardized test systems and brain morphology by magnetic resonance imaging., Results: All patients presented with high tyrosine concentrations in CSF correlating with increased plasma tyrosine levels and a reduced CSF serotonin turnover. MRI revealed no structural abnormalities in the brain. All patients presented with either impaired cognitive development or behavioural abnormalities., Conclusions: We here outline the need to further study the exact pathogenic mechanisms responsible for the neurotransmitter changes observed in HT type I in order to possibly prevent cognitive dysfunction. Nitisinone has significantly improved outcome and quality of life in HT type I; however, it is also accompanied by elevated plasma and CSF tyrosine. Further studies are essential to identify the necessary dietary tyrosine restriction and the optimal Nitisinone dose., (Copyright © 2010 Elsevier Inc. All rights reserved.)

This study is to investigate the influence and mechanism of action of asymmetrical dimethylarginine (ADMA) and the induced oxidative stress level on Alzheimer's disease (AD) incidence. ADMA concentration, nitric oxide, Abeta(40)/Abeta(42) ratio, inducible NO synthase (iNOS) activity and the concentrations of the induced free radicals including malondialdehyde (MDA), 3-nitrotyrosine (3-NT) and peroxynitrite (ONOO-) in the cerebrospinal fluid (CSF) from 34 neurologically normal controls and 37 AD patients were quantitatively determined and statistically compared. The results showed that the ADMA concentration significantly decreased in AD patients, and it showed negative correlation with the NO, iNOS activity, and showed positive correlation with MMSE score. ADMA concentration was negatively correlated with Abeta(40)/Abeta(42) ratio (P<0.01) with the observation that Abeta(40)/Abeta(42) ratio increased while ADMA level decreased in CSF in AD patients. The concentration levels of MDA, 3-NT and ROS significantly increased compared with the control with all the P values less than 0.05. These findings suggested that the ADMA disorder and the oxidative damage effect of the induced free radicals in CSF of AD patients are an important mechanism of AD incidence, and their joint regulation may provide new idea for the prevention and clinical treatment of AD.

Background: Cerebral vasospasm is a significant cause of morbidity in patients after aneurysmal subarachnoid hemorrhage (aSAH). There are few effective treatments. The search for new treatments has focused predominantly on dilating cerebral blood vessels. Growing evidence supports a role for inflammation in its pathogenesis but no potential target for intervention has emerged., Methods: CSF and clinical information from patients with aSAH were collected. Additionally, tyrosine modifications by stable isotope dilution HPLC with online tandem mass spectrometry were quantified in CSF samples., Results: We report an association between neutrophil accumulation in the cerebrospinal fluid of patients with aSAH and the development of vasospasm. In particular, CSF neutrophil content of >62% on the third day after aSAH is an independent predictor of the later development of vasospasm (OR 6.8, 95% CI 2.0-23.3, P = 0.002). Further, activity of myeloperoxidase and NADPH oxidase is elevated in aSAH suggesting a role for modification of CSF proteins by reactive oxidant species., Conclusions: Neutrophil percentage is an independent predictor of vasospasm in aSAH patients, days prior to its onset suggesting a role of neutrophils in vasospasm. The activity of neutrophil enzymes is also increased suggesting a mechanism for blood vessel damage. Inflammation mediated by neutrophils is a potential target for therapies in vasospasm. More study is necessary to determine the mechanism by which neutrophils damage cerebral blood vessels.

The goal of our study was whether free radicals contribute to the pathogenesis of the lacunar stroke to investigate the day after hospitalization, the concentrations of 3-nitrotyrosine and tyrosine in the cerebrospinal fluid (CSF) from living patients. The subjects included 20 living patients with lacunar stroke and 20 controls. The NIH stroke scale score was used to assess the severity of the stroke, including that the patients were mild cases. There was no expansion of the infarct lesion in the brain, as assessed by CT on the day following admission. The concentration of 3-nitrotyrosine was significantly higher in patients with lacunar stroke. In contrast, the concentration of tyrosine did not differ between the two groups. Furthermore, the 3-nitrotyrosine/tyrosine ratio was significantly higher in patients with lacunar stroke than in controls. Our results show that free radicals are produced in the CSF of lacunar stroke patients and that nitration of neuronal proteines is enhanced under this condition. These obsetvations suggest that lacunar stroke patients should be treated with edaravon, which is a free radical scavenger usually prescribed for cases of major strokes, as it will likely improve the prognosis of these patients.

Objectives: Many studies have shown differences in carbonylation and nitration of individual proteins in brain and body fluids of Alzheimer's disease (AD) patients. Therefore, we wanted to examine whether total levels of these oxidative stress markers of proteins were altered in AD., Patients and Methods: Total levels of carbonyls and nitrotyrosine in cerebrospinal fluid, serum and plasma were measured in 22 AD patients and 18 age-matched controls using commercially available enzyme immunoassay kits., Results: Protein carbonylation in cerebrospinal fluid did not differ between AD patients and controls but was decreased in APOE epsilon4 carriers as compared with non-carriers. Serum but not plasma levels of carbonyls tended to be decreased in AD patients as compared with aged controls. Nitrotyrosine concentrations did not differ between the groups. Surrogate cerebrospinal fluid markers for AD, beta-amyloid (1-42) and tau, correlated with blood carbonyl and nitrotyrosine levels., Conclusions: According to these preliminary data, changes in oxidative metabolism related to the pathogenesis of AD cannot be detected as increased cerebrospinal fluid, serum or plasma protein carbonylation or nitration.

To evaluate the possible role of central free amino compounds in pediatric opsoclonus-myoclonus syndrome (OMS), 21 cerebrospinal fluid (CSF) amino compounds were measured by an amino acid analyzer or mass spectroscopy in 74 anesthetized children, 54 with OMS and 20 age-matched neurological controls. In OMS, only phosphoethanolamine was increased compared to controls; OMS severity and duration had significant converse effects on alanine and phosphoethanolamine. In contrast, corticotropin (ACTH) treatment was associated with increased alanine and phenylalanine, and decreased taurine compared to controls and untreated OMS, and increased glutamine, lysine, ornithine, and tyrosine compared to untreated OMS. Other than low taurine, these effects were not found with corticosteroid treatment, and non-steroidogenic immunotherapy had no effect. The ACTH dose-association was most apparent for alanine and phosphoethanolamine, but lysine and ornithine were also higher in the high-dose ACTH group. There were no significant disease- or treatment-associated perturbations in GABA, glycine, or other amino acids. These data suggest a unique pattern of ACTH effects on non-neurotransmitter CSF amino compounds, for the most part not shared by steroids.

Background: The prevalence of HIV-associated neurocognitive disorders is increasing as HIV-infected individuals are living longer. The clinical manifestations of the syndrome also continue to evolve under the influence of antiretroviral drugs and comorbidities such as drugs of abuse. However, there are no surrogate markers for the disease, either to identify it de novo or to track its progression, and there is no proven treatment with the exception of antiretroviral drugs., Methods: Levels of nitric oxide, nitrate, and 3-nitrotyrosine (3-NT)-modified proteins were measured in the CSF of 46 patients with HIV infection stratified according to their neurocognitive status and history of IV drug use (IVD). The 3-NT-modified proteins were isolated and identified by tandem mass spectrometry, and the functional consequence of 3-NT modification of L-prostaglandin D synthase (L-PGDS), the most abundant protein, was determined., Results: 3-NT-modified proteins were significantly elevated in patients with HIV infection who had progressive neurocognitive decline over the next 6 months and in patients with a history of IVD. Thirteen different proteins with 3-NT modification were identified in the CSF of these patients. L-PGDS was the most abundant. 3-NT modification of this protein resulted in loss of its enzymatic activity., Conclusions: There is increased nitrosative stress in CSF of HIV-infected patients with active dementia and in patients with a history of IV drug use, measurement of which may serve as a surrogate marker for these patients. Nitrosative stress may also have important functional consequences and may impact the pathogenesis of HIV-associated neurocognitive disorders.

Different lines of evidence suggest that nitric oxide (NO) plays a key role in the pathogenesis of inflammatory neuropathies; however, it is still unclear which structures in the peripheral nerve are the primary targets of NO-mediated nerve injury. To address this issue, we determined the expression of NO metabolites in sural nerve biopsies and in cerebrospinal fluid from patients with inflammatory neuropathies and studied the pathologic effects of NO in an in vitro model of myelinated Schwann cell-neuron cocultures. In cerebrospinal fluid samples, nitrite levels remained unaltered; however, nitrotyrosine, a marker for peroxynitrite formation, could be identified in nerve biopsies from patients with inflammatory neuropathies. In an in vitro model of Schwann cell neuron cocultures, high concentrations of NO induced robust demyelination, which was the result of NO-mediated axonal injury, whereas Schwann cell viability remained unaffected. These findings suggest that in contrast to Schwann cells, sensory neurons are the primary target of NO-mediated cytotoxicity and the loss of myelin is the result of selective damage to axons rather than a direct harmful effect to Schwann cells. Our findings imply that NO contributes to the pathologic changes seen in the inflamed peripheral nervous system, which is characterized by the features of axonal injury and subsequent myelin degradation, previously described as Wallerian-like degeneration.

Long-term or high-dose L-DOPA therapy in patients with Parkinson's disease (PD) may accelerate degeneration of dopaminergic neurons, possibly by increasing oxidative stress. To investigate the effects of cabergoline on peroxynitrite-mediated oxidative damage caused by L-DOPA, the concentration of 3-nitrotyrosine in cerebrospinal fluid (CSF) of 18 PD patients was compared with that in 20 normal controls. The concentration of 3-nitrotyrosine in patients following L-DOPA therapy was significantly higher than in untreated PD patients and controls. On the other hand, the concentration in PD patients after cabergoline therapy was significantly lower than in PD patients after L-DOPA therapy alone. These data suggest that cabergoline scavenges peroxynitrite induced by L-DOPA in patients with PD.

This work presents two liquid chromatography/tandem mass spectrometry (LC/MS/MS) acquisition modes: multiple reaction monitoring (MRM) and neutral loss scan (NL), for the analysis of 28 compounds in a mixture. This mixture includes 21 compounds related to the metabolism of three amino acids: tyrosine, tryptophan and glutamic acid, two pterins and five deuterated compounds used as internal standards. The identification of compounds is achieved using the retention times (RT) and the characteristic fragmentations of ionized compounds. The acquisition modes used for the detection of characteristic ions turned out to be complementary: the identification of expected compounds only is feasible by MRM while expected and unexpected compounds are detected by NL. In the first part of this work, the fragmentations characterizing each molecule of interest are described. These fragmentations are used in the second part for the detection by MRM and NL of selected compounds in mixture with and without biological fluids. Any preliminary extraction precedes the analysis of compounds in biological fluids., (Copyright 2006 John Wiley & Sons, Ltd.)

Chronic bilirubin encephalopathy, characterized clinically by extrapyramidal movement abnormalities, vertical gaze abnormalities, and hearing loss, results from neuronal injury after marked hyperbilirubinemia in term and preterm infants. In premature infants, bilirubin staining of specific brain structures has been described at autopsy after only moderate hyperbilirubinemia, but classic chronic bilirubin encephalopathy without marked hyperbilirubinemia has been reported only rarely. We report a case of a 7-year-old, former 29-weeks' gestation, gravely ill premature infant with a peak bilirubin level of 13.3 mg/dL in the neonatal period. We compare this case with a 12-year-old, former term infant with a peak bilirubin level of 49.4 mg/dL on day 10 of life. Both children have dystonia, athetosis, upward gaze palsy, and sensorineural hearing loss, with MRIs showing characteristic abnormal signal in the globus pallidus. We add previously unreported cerebrospinal fluid neurotransmitter levels that show a mild decrease in the dopamine metabolite homovanillic acid in the former premature infant only.

Increased damage to proteins by glycation, oxidation and nitration has been implicated in neuronal cell death leading to Alzheimer's disease (AD). Protein glycation, oxidation and nitration adducts are consequently formed. Quantitative screening of these adducts in CSF may provide a biochemical indicator for the diagnosis of AD. To assess this, we measured 11 glycation adducts, three oxidation adducts and a nitration adduct, determining both protein adduct residues and free adducts, in CSF samples of age-matched normal healthy subjects (n = 18) and subjects with Alzheimer's disease (n = 32). In CSF protein, the concentrations of 3-nitrotyrosine, N(epsilon)-carboxymethyl-lysine, 3-deoxyglucosone-derived hydroimidazolone and N-formylkynurenine residues were increased in subjects with Alzheimer's disease. In CSF ultrafiltrate, the concentrations of 3-nitrotyrosine, methylglyoxal-derived hydroimidazolone and glyoxal-derived hydroimidazolone free adducts were also increased. The Mini-Mental State Examination (MMSE) score correlated negatively with 3-nitrotyrosine residue concentration (p < 0.05), and the negative correlation with fructosyl-lysine residues just failed to reach significance (p = 0.052). Multiple linear regression gave a regression model of the MMSE score on 3-nitrotyrosine, fructosyl-lysine and N(epsilon)-carboxyethyl-lysine residues with p-values of 0.021, 0.031 and 0.052, respectively. These findings indicate that protein glycation, oxidation and nitration adduct residues and free adducts were increased in the CSF of subjects with Alzheimer's disease. A combination of nitration and glycation adduct estimates of CSF may provide an indicator for the diagnosis of Alzheimer's disease.

The mechanisms behind the degeneration of neurons in diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) are not fully understood. However, oxidation of certain amino acid residues in proteins may contribute to cell injury and some of these oxidized amino acids may also be suitable as biomarkers for oxidative injury. Therefore, it is suggested that the reaction between peroxynitrite (ONOO(-)) and tyrosine in vivo can be monitored by monitoring the formation of 3-nitrotyrosine (3-NT). In this work, a newly developed gas chromatographic-mass spectrometric method was applied to human cerebrospinal fluid (CSF). The free 3-NT levels were determined in the CSF from 19 controls, 17 patients with AD and 14 patients with ALS. The levels of free 3-NT in the CSF were considerably lower than those previously reported. The majority of the patients with AD or ALS had free 3-NT levels in the same range as seen in the control individuals and only a few patients showed increased levels of free 3-NT.

Background: Deficiency of aromatic L-amino acid decarboxylase (AADC) is associated with severe developmental delay, oculogyric crises (OGC), and autonomic dysfunction. Treatment with dopamine agonists and MAO inhibitors is beneficial, yet long-term prognosis is unclear., Objective: To delineate the clinical and molecular spectrum of AADC deficiency, its management, and long-term follow-up., Results: The authors present six patients with AADC deficiency and review seven cases from the literature. All patients showed reduced catecholamine metabolites and elevation of 3-O-methyldopa in CSF. Residual plasma AADC activity ranged from undetectable to 8% of normal. Mutational spectrum was heterogeneous. All patients presented with hypotonia, hypokinesia, OGC, and signs of autonomic dysfunction since early life. Diurnal fluctuation or improvement of symptoms after sleep were noted in half of the patients. Treatment response was variable. Two groups of patients were detected: Group I (five males) responded to treatment and made developmental progress. Group II (one male, five females) responded poorly to treatment, and often developed drug-induced dyskinesias., Conclusions: The molecular and clinical spectrum of AADC deficiency is heterogeneous. Two groups, one with predominant male sex and favorable response to treatment, and the other with predominant female sex and poor response to treatment, can be discerned.

3-Nitrotyrosine is a useful marker for nitric oxide-mediated tissue injury. However, which proteins are preferred peroxynitrite modification targets is unclear. Chondroitin sulfate proteoglycans (CSPGs) abnormally accumulate in cerebrospinal fluid of human neonates with hydrocephalus and may be a target for peroxynitrite modification. We examined (1). whether CSPG core protein can be modified by peroxynitrite in vitro; (2). to what degree in comparison to bovine serum albumin (BSA), the most commonly used nitrated protein standard; (3). whether nitrated CSPGs can be measured directly in biological samples; and (4). whether nitrated proteoglycan concentrations in cerebrospinal fluid correlate with disease. In vitro nitration of bovine aggrecan was performed by exposure to different peroxynitrite concentrations, and 3-nitrotyrosine products were measured. Bovine serum albumin (BSA) nitration was also performed in comparison. A larger percentage of tyrosine residues were nitrated in aggrecan than in BSA under all conditions tested. An enzyme-linked immunosorbent assay (ELISA) for 3-nitrotyrosine consistently overestimated aggrecan nitration when nitrated BSA was used as the standard. This is important as most current assays of nitration in biological samples use nitrated BSA as the standard. Therefore, if nitrated CPSGs were a substantial portion of the nitrated proteins in a sample, total nitrated protein content would be overestimated. Aggrecan retained its function of binding hyaluronic acid despite substantial nitration. A double-sandwich ELISA was developed for nitrated CSPGs in biological samples, using nitrated aggrecan as standard. [Nitrated CSPG] was found to be significantly elevated in preterm hydrocephalus cerebrospinal fluid (P<0.02), but correlated poorly with cerebrospinal fluid [nitric oxide] (P>0.069), suggesting that nitrated CSPG and NO levels may be independant markers of tissue injury. Peroxynitrite-mediated protein tyrosine nitration is a previously unrecognized modification of CSPGs, and may reflect level of brain injury in hydrocephalus.

For the purpose of this study, we used a "ball lens" UV laser-induced fluorescence (LIF) detector comprising a pulsed laser and a collinear optical arrangement. The fluorescence signal is induced by a pulsed laser and detected by a photomultiplier tube. When coupling the high-frequency pulsed laser to the LIF detector we used, the electronics which is designed for continuous wavelength (CW) lasers, "viewed" the laser as a continuous source. Despite this mismatch between the laser and the "ball lens" UV LIF detector, the sensitivity we obtained with tryptophan is comparable to the one obtained with the best "laboratory-made" detector described in the literature which used a CW UV laser. Limits of detection of 0.15 nM for tryptophan and 50 nM for tyrosine were estimated. As an application of this technology, we studied tryptophan and tyrosine in cerebrospinal fluids (CSFs). The analysis is very simple and works on very small samples (5 microl). It consists of using a 10 mM 3-cyclohexylamino-1-propanesulfonic acid, 15 mM sodium tetraborate, pH 9.2 buffer and injecting CSF diluted 20 times in water prior to injection. 5-Hydroxyindoleacetic acid was used as an internal standard. The separation is completed in less than 12 min. The capillary electrophoresis method which we chose is rapid, resolutive and allows accurate measurements. Recovery experiments in CSFs show recoveries between 97 and 102%. We investigated 14 different CSFs from patients who suffered from neurological disorders. Most of the concentrations vary in a range of 1.7 to 3.7 microM for Trp and 6.6 to 13.7 microM for Tyr, which is in the range observed in the literature. One patient who suffers from Huntington disease had a higher concentration of Tyr at 17.3 microM.

The objective of this study was to determine the role of cerebral nitric oxide and its powerful oxidant peroxynitrite following mild birth asphyxia. The cerebrospinal fluid levels of nitric oxide and 3-nitrotyrosine as a marker for peroxynitrite are measured in neonates with mild hypoxic-ischemic encephalopathy. Based on the classification of Sarnat and Sarnat, term neonates with mild hypoxic-ischemic encephalopathy and neurologically normal neonates suspected of sepsis were taken as the control group. Nitric oxide measurements were done by chemiluminescence, and nitrotyrosine measurements were made by high-performance liquid chromatography. The Mann Whitney U-test was used, and a Pvalue < .05 was considered significant. Eleven patients with grade 1 hypoxic-ischemic encephalopathy and nine controls were included. The gestational age and birthweights were similar in both groups. Neither of the cerebrospinal fluid levels of nitric oxide (8.60 +/- 0.49 micromol/L) and nitrotyrosine (0.45 +/- 0.33 micromol/L) of the neonates with hypoxic-ischemic encephalopathy showed significant differences from that of the means of nitric oxide (8.66 +/- 1.07 micromol/L) and nitrotyrosine levels (0.25 +/- 0.13 micromol/L) of the controls. These data suggest that the oxidative stress is not overexpressed to lead nitric oxide and peroxynitrite to play a pathologic role in the early phase of mild hypoxic-ischemic encephalopathy of the newborn.

In order to define an activity profile in patients with multiple sclerosis (MS), T-cell subpopulations and proliferative responses to myelin basic protein (MBP) associated with anti-MBP antibodies, nitrotyrosine levels in serum and cerebrospinal fluid (CSF), and serum CD40L (sCD154) were simultaneously assessed in 29 consecutive and untreated MS patients. When compared to controls, patients in secondary progressive stable (SP/I), or in full remission (RR/I) stages, individuals with secondary progressive active disease (SPIA) or in acute relapse (RR/A) showed a significant decrease of CD4/CD45RA+ T cells associated with an increase of absolute numbers of CD4/45R0+ T cells (p < 0.001). In addition, in vitro-specific T-cell proliferative responses against MBP (SP/A, RR/A, SP/I: p < 0.001 versus controls) in association with augmented sCD154 serum levels (SP/A, RR/A, versus controls p < 0.001) and a significant increase of both CSF and serum levels of anti-MBP antibodies and nitrotyrosine levels (p < 0.001) were also found. Thus, the simultaneous evaluation of antibody and cell-mediated immunopathological parameters, along with the effector mediators of inflammation such as the nitric oxide products, offers a new integrative approach to characterize markers of clinical activity in MS patients, which may be used at the moment of the initial diagnosis and during an apparent recurrences of the disease to monitor therapeutic protocols and to determine whether immune-based nerve destruction mechanisms are still operating in patients with few clinical findings.

Objective: To study reactive nitrogen species-mediated oxidative brain damage and antioxidant defenses in patients with acute bacterial meningitis., Methods: Nitrotyrosine (a widely used marker for the formation of reactive nitrogen species, such as peroxynitrite) and the lipid peroxidation product 4-hydroxynonenal were detected by immunohistochemistry in brain specimens obtained at autopsy. CSF concentrations of nitrotyrosine were quantified by ELISA. CSF and serum concentrations of ascorbic acid, uric acid, and its oxidation product allantoin were determined by high-pressure liquid chromatography., Results: Tyrosine nitration was strongly increased during meningitis. It was most evident in inflammatory cells and blood vessels in the subarachnoid space. The same cell types stained positive for the lipid peroxidation marker 4-hydroxynonenal, suggesting that reactive nitrogen species contribute to oxidative brain damage during meningitis. High CSF nitrotyrosine concentrations were associated with an unfavorable outcome according to the Glasgow Outcome Score. In the CSF, the increase of nitrotyrosine was accompanied by a depletion of the antioxidant ascorbic acid and an increased oxidation of the natural peroxynitrite scavenger uric acid to allantoin., Conclusion: These findings indicate that oxidative stress due to reactive nitrogen species and altered antioxidant defenses are involved in the pathophysiology of bacterial meningitis in humans.

Using a Coulochem electrode array system, we investigated the developmental changes of monoamine-related substances in patients with dentatorubral-pallidoluysian atrophy. The patterns observed in the developmental changes of tryptophan, tyrosine, homovanillic acid (HVA), 3-O-methyldopa, and 3-methoxy4-hydroxyphenyl glycol (MHPG) in patients with dentatorubral-pallidoluysian atrophy are quite different from those in control subjects. These abnormal developmental changes in monoamine-related substances may be implicated in age-related differences in clinical symptoms of dentatorubral-pallidoluysian atrophy.

The interpretation of data on compounds in the lumbar cerebrospinal fluid (CSF) is limited by several confounding factors, e.g. motor activity for which strict bed rest prior to lumbar puncture is recommended for standardisation. Now we report data from 14 healthy males employing the standardised procedure except for the requirement of strict bed rest. The levels of serotonin, noradrenaline, 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid and 4-hydroxy-3-methoxyphenylglycol in the second CSF fraction (7-12 ml) were significantly higher than those in the first fraction (0-6 ml), indicating the presence of concentration gradients. 5-HIAA was negatively influenced by age and the neuraxis distance in the lying position and positively by atmospheric pressure. Storage time and atmospheric pressure contributed to the variance in dopamine. Both tyrosine, tryptophan and dopamine were linearly correlated with storage time. We also found a significant curvilinear correlation between tapping time and atmospheric pressure. On comparing with previous studies, the results support the notion that the issue of strict bed rest or not prior to lumbar puncture might have to be taken into consideration when interpreting lumbar monoamine CSF data., (Copyright 2001 S. Karger AG, Basel)

Background: Connections between mood changes and weather have been described throughout the ages, and in more recent years, there have been reports on a relationship between atmospheric pressure and neurotransmitter levels in cerebrospinal fluid., Methods: To further investigate this issue under strictly standardized conditions, we have lumbar-punctured 8 healthy males under low (963 hPa) and high (1064 hPa) barometric pressure, using a pressure chamber., Results: Under high pressure, the tyrosine concentrations in the cerebrospinal fluid (CSF) were lower, while the cholecystokinin tetrapeptide (CCK-4) levels were higher. No differences between low and high pressure were found for tryptophan, 5-hydroxyindolacetic acid (5-HIAA), dopamine (DA), and sulphated cholecystokinin octapeptide (CCK-8S). The serum level of CCK-8S was higher under high pressure. On comparing concentration ratios between the second and the first CSF fraction, we found significantly increased ratios for homovanillic acid (HVA) and 4-hydroxy-3-methoxyphenylglycol (HMPG), but a decreased ratio for tyrosine under high pressure. The difference in the concentration ratios of HVA between low and high pressure correlated negatively with age. Intraspinal pressure correlated negatively with tapping time at low pressure., Conclusion: Our results are in line with the hypothesis that atmospheric pressure influences CSF levels of monoamine compounds and cholecystokinin peptides.

We have analyzed changes in cerebrospinal fluid (CSF) concentrations of monoamine-related substances to clarify the mechanism of the antiepileptic action of thyrotropin-releasing hormone (TRH). TRH-tartrate was administered to 14 patients with intractable epilepsy. Before and 2 weeks after TRH administration, CSF was collected and analyzed for tryptophan and tyrosine metabolites. Among monoamine-related substances, only CSF concentrations of kynurenine were increased after TRH therapy. Considering the fact that kynurenic acid acts as antagonist on the NMDA receptor complex, the results of this study may explain at least one of the mechanisms of the effectiveness of TRH therapy for intractable epilepsy.

To investigate the significance of nitric oxide (NO)-mediated neuron death in aging and Alzheimer's disease (AD), the 3-nitrotyrosine concentration in the cerebrospinal fluid (CSF) was investigated in neurologically normal controls and patients with AD. The 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio significantly increased with advancing age, whereas the tyrosine concentration was unaltered. In patients with AD, the 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio increased significantly (>six-fold) compared with controls of similar age, and increased significantly with decreasing cognitive functions, whereas the tyrosine concentration did not change. These findings suggest that an activation of tyrosine nitration, increase in nitrated tyrosine-containing proteins, and/or its degradation may be involved in brain aging and play an important role in the pathogenesis of AD.

To investigate the significance of peroxynitrite-mediated oxidative damage in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS), the concentrations of 3-nitrotyrosine and tyrosine in the cerebrospinal fluid (CSF) of patients with SALS were determined. The concentration of 3-nitrotyrosine and the 3-nitrotyrosine/ tyrosine ratio in patients with SALS were approximately seven times those of controls. Thus, the present findings in living patients provide in vivo evidence for a possible role of peroxynitrite, a mediator of oxidative stress, and increased nitration of tyrosine residues in the pathogenesis of SALS.

This study addresses two issues: (1) the comparative neurochemistry of classic tremor type of Parkinson's disease or PD-A and akinetic type of Parkinson's disease or PD-B; and (2) the neurochemistry of levodopa failure syndrome (LDFS). Cerebrospinal fluid from the lateral ventricle was collected from 50 patients with idiopathic Parkinson's disease of PD-A and PD-B. Levels of monoamine neurotransmitters and metabolites were determined using high performance liquid chromatography. We have found that (1) 5-hydroxylindoleacetic acid (5-HIAA) level is significantly lower in PD-B than in PD-A; (2) 5-HIAA level is inversely associated with score of part one of United Parkinson's Disease Rating Score (UPDRS); (3) 5-HIAA level is inversely associated with score of part four of UPDRS; (4) 3-O-methyldopa (3-OMD) level is positively associated with levodopa failure syndrome (LDFS) assessed by part four of UPDRS and inversely associates with 5-HIAA. From these data, it can be inferred that serotonergic activity is decreased in PD-B to a greater extent than in PD-A and that decreased serotonergic activity plays a role in LDFS.

The tryptophan (TRP) depletion paradigm has been employed to investigate mood and behavioral effects of acutely lowering plasma TRP, and presumably brain serotonin (5-hydroxytryptamine [5-HT]) levels through administration of a special diet and/or amino acid drink. Our goal was to test the assumption that a corresponding fall in central levels of TRP and 5-HT (measured by its major metabolite, 5-hydroxyindoleacetic acid [5-HIAA]) occurs during the standard execution of this method in healthy adult subjects. Three males and two females completed the protocol, which included a one-day low-TRP diet and a TRP-free amino acid drink. Lumbar puncture was performed, with placement of an indwelling catheter connected to a peristaltic pump and fraction collector. Cerebrospinal fluid (CSF) was sampled continuously for a 13.5-hour period (before, during, and after the drink), with fractions removed every 15 minutes. Plasma samples were simultaneously obtained. CSF TRP levels and plasma TRP levels were highly correlated, falling a mean of 92% and 85% from baseline, respectively. CSF nadirs were reached several hours after plasma nadirs. CSF 5-HIAA decreased modestly (24% to 40%, mean 31% change from baseline), with lowest concentrations observed 8-12 hours after the amino acid drink. These data suggest that TRP depletion results in substantial declines in central 5-HT turnover.

P300 and cerebrospinal fluid neurotransmitter metabolites and amino acids were examined in 10 patients with Alzheimer's disease, 9 patients with vascular dementia and 10 healthy controls. A negative correlation between P300 amplitude and MHPG concentration, negative correlation between P200 and N200 latencies and norepinephrine concentration, positive correlation between N200 latency and lysine concentration and positive correlation between N100 amplitude and tyrosine concentration were statistically significant. These findings suggest that the noradrenergic system influences P300 amplitude, and that multiple systems may influence P300 components.

The study was carried out on the lumbar cerebrospinal fluid (CSF) samples taken from nonparkinsonian, early parkinsonian, and advanced parkinsonian patients. Some patients showed dementia, and some were treated with L-dopa. In the samples, salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) was assayed with a newly developed sensitive high-performance liquid chromatography (HPLC) method; 3-O-methyldopa (3-O-MD) and homovanillic acid (HVA) were also assayed by HPLC. CSF salsolinol concentrations were significantly enhanced in patients with signs of dementia, regardless of the degree of parkinsonism, and were not affected by L-dopa treatment; HVA and, particularly, 3-O-MD levels were elevated in patients receiving L-dopa. The strong association of CSF salsolinol level with dementia, but not with L-dopa treatment suggests that salsolinol does not originate from L-dopa metabolism, and that its elevation is an indicator of neurodegenerative processes resulting in damage to brain areas mediating cognitive functions. We found no correlation between the advancement of parkinsonism and the concentrations of 3-O-MD and HVA.

Salsolinol is one of the dopamine-derived tetrahydroisoquinolines, supposed to be a potent dopaminergic neurotoxin, similar to MPTP. Its systemic administration induced parkinsonism in monkeys. The aim of the study was to compare the concentration of salsolinol and the metabolite of L-dopa, 3-O-MD, and the metabolite of dopamine, HVA, in the cerebrospinal fluid of patients with different degrees of parkinsonism, treated or nontreated with l-dopa. Lumbar CSF was obtained from 26 patients with Parkinson's disease (15 early and 11 advanced parkinsonism) and from six healthy controls. The presence of salsolinol, HVA and 3-O-MD was assayed with a sensitive HPLC method employing C18 (Hypersil BDS) column. The analysis of the results demonstrated that the concentration of salsolinol was related to the degree of parkinsonism but not affected by l-dopa treatment. In contrast, HVA and 3-O-MD were significantly elevated in patients receiving l-dopa but did not correlate with the severity of parkinsonism. The results suggest that salsolinol in the cerebrospinal fluid does not originate from exogenous l-dopa and its elevation in cerebrospinal fluid may be an indicator of the advancement of parkinsonism.

A micro-scale method for separation and measurement of dityrosine in human cerebrospinal fluid (CSF) is described utilizing liquid-liquid extraction and ion-paired, reversed-phase high-performance liquid chromatography with fluorimetric detection. A mobile phase containing 1-heptanesulfonic acid linearly increased in methanol from 0 to 100% over 30 min allows the resolution of dityrosine from other fluorescent compounds with excitation at 285 nm and emission at 410 nm. As little as 0.15 ml CSF sample can be utilized with a detection limit of 60 pg dityrosine on the column. This method facilitates the use of CSF dityrosine as a measure of free radical mediated protein damage in the central nervous system.

Since motor fluctuations in Parkinsonian patients might be, at least in part, explained by an antagonism between levodopa (LD) and its metabolite 3-O-methyldopa (3-OMD) at blood-brain-barrier (BBB), we decided to study LD and 3-OMD plasma and cerebrospinal fluid (CSF) levels in subjects undergoing lumbar puncture for diagnostic purposes. After informed consent, 70 subjects took a tablet of carbidopa-levodopa association (Sinemet or Sinemet-CR) 0.5, 1, 2, 4, 8, 12 h before blood and lumbar cerebrospinal fluid collection. LD and 3-OMD were determined by an HPLC-electrochemical method. The subjects treated with Sinemet-CR had lower LD cerebrospinal fluid concentrations along with lower LD and higher 3-OMD plasma concentrations. This pattern of LD cerebrospinal fluid concentrations may be explained by means of a transport competition between LD and 3-OMD at blood brain barrier level.

Changes of monoamines, monoamine metabolites, neuron specific enolase (NSE) and myelin basic protein (MBP) levels in cerebrospinal fluid were measured in 8 patients for up to 7 days after cardiopulmonary resuscitation. The outcomes were assessed by the Glasgow Outcome Scale. One showed good recovery 3 developed a persistent vegetate state (PVS) and 4 became brain dead (BD). The concentration of NSE increased to a peak about 3 days after resuscitation, then gradually decreased. MBP also showed an increase with time up to 7 days. The time course suggests that neuronal and/or axonal damage progresses for several days after hypoxic or anoxic brain insult. NSE and MBP in the BD group were higher than those in the PVS group, thus CSF levels may be prognostic with regard to hypoxic brain injury. Tyrosine, dopamine, 3-methoxytyramine (3-MT), 3-dihydroxy-4-phenylacetic acid (DOPAC), homovanillic acid (HVA), vanillylmanderic acid (VMA), normetanephrine (NMN), metanephrine (MN), 3-methoxy-4-hydroxyphenylglycol (MHPG), vanillic acid (VA), tryptophan and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were analyzed by HPLC with an electrochemical detector. Concentrations changed within 2 or 3 days after resuscitation, so concentrations at that period may indicate neuronal damage. However, there are some cases with abnormal NSE and MBP levels without abnormal monoamine levels, suggesting that differences in concentrations are not the consequence of the amount of affected neurons, but of the sites of regions.

Associations in 52 normal individuals were examined between plasma and cerebrospinal fluid (CSF) concentrations of tryptophan (Trp) and tyrosine, and concentrations of monoamine metabolites in the CSF, and scores on an aggression questionnaire, the Kinsey Institute Reaction List II, and the Eysenck Personality Questionnaire. There was a significantly positive correlation between CSF 5-hydroxyindoleacetic acid (5-HIAA) levels and extroverted aggression scores, and a significantly negative correlation between CSF 5-HIAA levels and introverted aggression scores. Males showed higher plasma Trp concentrations than females, and significantly positive correlations between plasma Trp concentrations and scores on extroverted aggression and the Eysenck E scale. Males, furthermore, showed a significantly negative correlation between CSF Trp levels and scores on the Eysenck P scale, and a significantly positive correlation between concentrations of 3-methoxy-4-hydroxy-phenylglycol in CSF and scores on moral aggression. These results suggest that central serotonin influences aggression in normal individuals through effects on personality.

We studied biochemical parameters related with central dopaminergic neurotransmission in migraine patients during crisis. We determined tyrosine and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in cerebrospinal fluid (CSF) of 47 patients, 29 suffering migraine without aura and 18 suffering migraine with aura, comparing them with 27 control subjects. Tyrosine levels did not differ significantly between patients and controls. The CSF concentration of DOPAC was 0.73 +/- 0.55 ng/ml in the control population, 3.84 +/- 2.08 ng/ml in patients with migraine without aura and 3.30 +/- 1.49 ng/ml in patients suffering migraine with aura. The concentration of DOPAC correlated positively with the intensity of headache. These results suggest that patients with migraine have a central dopaminergic hyperfunction, probably related to a coexisting central dysfunction of noradrenergic neurotransmission.

We could quantify the tetrahydroisoquinoline derivative salsolinol in urine of patients with Parkinson's disease and normal control subjects by means of high performance liquid chromatography and electrochemical detection. Urine levels of salsolinol were positively related to the homovanillic acid/3-O-methyl-dopa ratio in the cerebrospinal fluid that reflects dopamine metabolism. In the patient group with visual hallucinations, mean salsolinol level was significantly increased to almost the 3-fold of those found in patients without hallucinations. Since the daily L-dopa doses of both patient groups were nearly identical this result is not due to different L-dopa medications. Additionally, either high values of the main serotonin metabolite, 5-hydroxyindole acetic acid (HIAA) or the L-dopa/3-O-methyl-dopa ratio were found in cerebrospinal fluid of patients with hallucinations. The enhanced salsolinol levels in patients with visual hallucinations seem to be due to an overloaded dopaminergic pathway with an imbalance between dopaminergic and serotonergic systems. Thus, salsolinol appears as a predictor for hallucinosis in Parkinson's disease.

The effects of neonatal hydrocephalus on the levels of tyrosine, tryptophan, 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) in CSF were determined by high-performance liquid chromatography (HPLC) with fluorometric detection in normal and chronically hydrocephalic rabbits. The hydrocephalic rabbits showed a highly significant increase in both the serotonin metabolite 5-HIAA and the dopamine metabolite HVA. There were no significant effects of the hydrocephalus on either tyrosine or tryptophan levels. There was a significant positive correlation between the intracranial pressure (ICP) and the increase in 5-HIAA and HVA, but not with the two precursor amino acids. There was a significant decrease in these amino acid precursors with age in both groups. A trend towards higher levels of 5-HIAA and HVA in older rabbits was also evident, however this change was not to the degree found in the hydrocephalics. These data indicate that increased ICP affects the mechanism of removal of 5-HIAA and HVA from the cerebrospinal fluid.

We could identify the MPTP-like compound and isoquinoline derivative N-methyl-norsalsolinol (2-MDTIQ) in cerebrospinal fluid (CSF) of patients with Parkinson's disease. The presence of 2-MDTIQ negatively correlated with the disease duration. In order to study the relationship between presence of 2-MDTIQ and dopamine metabolism, we examined 3-O-methyl-dopa (MDOPA) and homovanillic acid (HVA) levels in CSF of 15 normal control subjects and 34 patients with Parkinson's disease (PD). In the PD group in which 2-MDTIQ was detected, the HVA/MDOPA ratio was also negatively correlated with the duration of the disease and was increased when compared to patients without 2-MDTIQ. Since in both PD groups the daily L-dopa dose, the mean MDOPA levels, and the daily L-dopa dose/MDOPA ratio were nearly identical the results are not related to different L-dopa medications. In vitro experiments demonstrated 2-MDTIQ to inhibit monoamine oxidase activity in the caudate-putamen. These results suggest that 2-MDTIQ indicates an increased dopamine turnover in patients with PD. The enhanced metabolism at the beginning of the disease is not due to the presence of 2-MDTIQ since it inhibits dopamine metabolism. Thus, 2-MDTIQ, probably endogenously synthesized from dopamine, appears as a result of a compensatively activated dopaminergic system.

We compared the concentrations of dopaminergic substances in the plasma and cerebrospinal fluid (CSF) with clinical severity in patients with Parkinson's disease (PD) under L-dopa/carbidopa treatment and under L-dopa/carbidopa+tolcapone treatment. Compared with treatment with L-dopa/carbidopa alone, the co-administration of tolcapone produced a significant decrease in clinical severity; a remarkable reduction in the 3-O-methyldopa (3-OMD) concentration and significant increase in the L-dopa concentration both in the plasma and CSF; and a significant increase in the dopamine concentration in the CSF. The clinical effects of tolcapone were closely correlated with the reduction in the 3-OMD concentration, but not with the increase in the dopamine and L-dopa concentrations in the CSF.

As part of a multidimensional study of cerebrospinal fluid biogenic amine metabolites in schizophrenia, the relationship between neurochemical measures and psychopathology assessed using the Psychiatric Symptom Assessment Scale (PSAS) was analyzed. In a group of 20 unmedicated patients, 3,4-dihydroxyphenylacetic acid (DOPAC) was a predictor of symptom severity in a stepwise multiple regression model. Values of 3-hydroxykynurenine and metanephrine in the unmedicated state predicted clinical response in a stepwise multiple regression model, as measured by improvement in PSAS mean item score following 6 weeks on a standard dose of neuroleptic. In a subgroup of 14 patients in whom both off- and on-medication concentrations of cerebrospinal fluid biogenic amines and metabolites were measured, change in 3-hydroxykynurenine predicted clinical outcome in a multiple regression model. These findings point toward the need to examine the role of the kynurenine pathway of tryptophan metabolism in the pathophysiology of schizophrenia.

Recent hypotheses and findings indicate that measurements of interactions between cerebrospinal fluid (CSF) biogenic amine systems, rather than measurement of CSF biogenic amine metabolites, better correlate with clinically important findings in schizophrenia. To test hypotheses, we used a recent technological advance in high performance liquid chromatography with electrochemical detection and combined it with multivariate statistical analyses to study biogenic amine concentrations in CSF in schizophrenia. This approach enabled the study of the interactions of several metabolites of each of the three major neurotransmitter pathways (dopaminergic, noradrenergic, and serotonergic) to test existing hypotheses regarding the neurobiochemical basis of schizophrenia. Twenty biogenic amines, their metabolites, and other compounds from 24 medication-free schizophrenic patients and 12 normal control subjects were simultaneously measured using a recently developed technique of gradient high performance liquid chromatography coupled with a 16-channel electrochemical array detector. After covariation for storage time, results of a stepwise discriminant function analysis comparing the control and patient groups identified tryptophan, tryptophol, and epinephrine as discriminating variables. Hotelling's paired T2 test from a subgroup of schizophrenic patients studied while they were and were not receiving neuroleptic treatment did not yield any significant differences between subgroups. A discussion of the findings and a comparison with previous studies of CSF biogenic amines in schizophrenia are presented.