Identification and quantification of (poly)phenol and methylxanthine metabolites in human cerebrospinal fluid: evidence of their ability to cross the BBB

Increasing evidence suggests that dietary (poly)phenols and methylxanthines have neuroprotective effects; however, little is known about whether they can cross the blood-brain barrier (BBB) and exert direct effects on the brain. We investigated the presence of (poly)phenol and methylxanthine metabolites in plasma and cerebrospinal fluid (CSF) from 90 individuals at risk of dementia using liquid chromatography-mass spectrometry and predicted their mechanism of transport across the BBB using in silico modelling techniques. A total of 123 and 127 metabolites were detected in CSF and plasma, respectively. In silico analysis suggests that 5 of the 20 metabolites quantified in CSF can cross the BBB by passive diffusion, while at least 9 metabolites require the aid of cell transporters to cross the BBB. Our results showed that (poly)phenols and methylxanthines are bioavailable, can cross the BBB via passive diffusion or transport carriers, and can reach brain tissues to exert neuroprotective effects.

Sex and race differences of cerebrospinal fluid metabolites in healthy individuals

INTRODUCTION

Analyses of cerebrospinal fluid (CSF) metabolites in large, healthy samples have been limited and potential demographic moderators of brain metabolism are largely unknown.

OBJECTIVE

Our objective in this study was to examine sex and race differences in 33 CSF metabolites within a sample of 129 healthy individuals (37 African American women, 29 white women, 38 African American men, and 25 white men).

METHODS

CSF metabolites were measured with a targeted electrochemistry-based metabolomics platform. Sex and race differences were quantified with both univariate and multivariate analyses. Type I error was controlled for by using a Bonferroni adjustment (0.05/33 = .0015).

RESULTS

Multivariate Canonical Variate Analysis (CVA) of the 33 metabolites showed correct classification of sex at an average rate of 80.6% and correct classification of race at an average rate of 88.4%. Univariate analyses revealed that men had significantly higher concentrations of cysteine (p < 0.0001), uric acid (p < 0.0001), and N-acetylserotonin (p = 0.049), while women had significantly higher concentrations of 5-hydroxyindoleacetic acid (5-HIAA) (p = 0.001). African American participants had significantly higher concentrations of 3-hydroxykynurenine (p = 0.018), while white participants had significantly higher concentrations of kynurenine (p < 0.0001), indoleacetic acid (p < 0.0001), xanthine (p = 0.001), alpha-tocopherol (p = 0.007), cysteine (p = 0.029), melatonin (p = 0.036), and 7-methylxanthine (p = 0.037). After the Bonferroni adjustment, the effects for cysteine, uric acid, and 5-HIAA were still significant from the analysis of sex differences and kynurenine and indoleacetic acid were still significant from the analysis of race differences.

CONCLUSION

Several of the metabolites assayed in this study have been associated with mental health disorders and neurological diseases. Our data provide some novel information regarding normal variations by sex and race in CSF metabolite levels within the tryptophan, tyrosine and purine pathways, which may help to enhance our understanding of mechanisms underlying sex and race differences and potentially prove useful in the future treatment of disease.

HPLC method for measurement of purine nucleotide degradation products in cerebrospinal fluid

We describe a convenient method for the separation and quantification of xanthine, hypoxanthine, and uric acid in 20 microL of cerebrospinal fluid (CSF) with use of HPLC and ultraviolet detection. The analysis is performed on a Sepharon SGX C18 column and the elution system consists of potassium phosphate buffer, pH 5.1, with 20 mL/L methanol. The lower limit of detection was 4 pmol for hypoxanthine and xanthine and 6 pmol for uric acid. Analytical recoveries of purine metabolites ranged from 98.6% to 102.9%. The intra- and interassay CVs were <3%. The applicability of the method is illustrated with the determination of micromolar concentrations of xanthine, hypoxanthine, and uric acid in CSF samples obtained from 113 patients with various neurological disorders.

Xanthine analysis in biological fluids by capillary electrophoresis

Xanthine, a precursor of uric acid, is measured here in serum, urine, and cerebrospinal fluids by capillary electrophoresis (CE) after deproteinization with acetonitrile. The migration time is about 7.5 min with a minimum detection limit of 0.4 mg/l. Different purines and pyrimidines did not interfere with the determination. The method demonstrates the suitability of the CE for determination of small molecules present in a complex matrix at levels of ca. 1mg/l. It also demonstrates that acetonitrile deproteinization is a simple and effective method for preparing samples for CE, allowing a large volume to be introduced into the capillary.

Concentration of purine compounds in the cerebrospinal fluid of infants suffering from sepsis, convulsions and hydrocephalus

Catabolites of purine nucleotides were measured in the cerebrospinal fluid (CSF) of newborn infants with sepsis, seizures and hydrocephalus using isocratic reversed-phase HPLC. The inosine levels in the CSF of the infants with any of the illnesses were significantly higher when compared with the controls. There was a tendency for hypoxanthine levels to be higher in the group of children with hydrocephalus. No significant differences in the concentrations of xanthine, adenine and uric acid were found. The inosine concentration in the CSF is proposed to be a more sensitive indicator of brain injury than the levels of other CSF purines. The levels of all purine metabolites measured in the CSF showed large individual variations. The ratio between hypoxanthine (as an indicator of ATP breakdown) and uric acid (as a scavenger of oxygen free radicals) concentration is proposed as a new criterion to be used in the evaluation of brain injury.

Effects of asphyxia on the fetal lamb brain

OBJECTIVE

Our purpose was to study the effect of fetal asphyxia on the release of hypoxanthine and xanthine in cerebrospinal fluid and on brain histologic characteristics.

STUDY DESIGN

In seven fetal lambs (3 to 5 days after surgery, gestational age 124.3 +/- 2.6 days) asphyxia was induced by restriction of uterine blood flow.

RESULTS

Fetal pH and base excess were reduced to 6.99 +/- 0.02 and -17.6 +/- 0.9 mmol/L, respectively. Cerebral blood flow increased during asphyxia and returned to normal in the recovery phase. Maximum concentrations of cerebrospinal fluid hypoxanthine and xanthine were reached in the normoxemic recovery phase. This high level of substrates during normoxemia facilitates oxygen free radical formation and may thus aggravate postasphyctic brain damage. Histologic evaluation of the brain 3 days after the insult showed a variable degree of edema. Coagulative neuronal changes, characteristic of irreversible cell death, were only occasionally detected. These changes were most obvious in the Purkinje cells of the cerebellum.

CONCLUSIONS

Fetal asphyxia induced by uterine blood flow restriction is associated with high levels of cerebrospinal fluid hypoxanthine and xanthine in the recovery phase. Microscopically detectable brain damage, although not extensive, is mainly located in the cerebellum.

The effect of age on concentrations of monoamines, amino acids, and their related substances in the cerebrospinal fluid

We studied age-related changes in the concentrations of monoamines, amino acids, and their related substances in the cerebrospinal fluid on 144 neurologically normal subjects. The concentrations of tyrosine, 3-O-methyldopa, dopamine (total), norepinephrine (total), homovanillic acid, p-hydroxyphenylacetic acid, and 5-hydroxytryptophan increased significantly with age (p < 0.05), and the concentration of 3.4-dihydroxyphenylacetic acid displayed a non-significant trend to decrease, whereas concentrations of other monoamine precursors and metabolites were unchanged. We found the significant positive correlations between the concentrations of HVA and 5-HIAA (p < 0.001), between tyrosine and tryptophan (p < 0.001), and between tyrosine and 3-O-methyldopa (p < 0.001). The concentrations of asparagine, glycine, taurine, and alanine increased significantly with age (p < 0.05), while glutamine, arginine, and threonine concentrations did not change with age. The aspartate, glutamate, and GABA concentrations displayed the non-significant trends to decrease in the elderly subjects. The concentrations of aspartate, glutamate, and GABA had mutually significant positive correlations (p < 0.05), but had significant negative correlations with the concentrations of some neutral amino acids. The urate and xanthine concentrations increased significantly with age (p < 0.01). These findings suggest that the concentrations of monoamine and amino acid transmitters and their related compounds in the cerebrospinal fluid reflect age-related changes in the synthesis, release, and reuptake mechanisms of the transmitters and their transport mechanisms across the blood-brain barrier.

Concentrations of nucleotides, nucleosides, purine bases and urate in cerebrospinal fluid of children with meningitis

The release of agents mediating inflammation in meningitis may bring about neuronal hypoxia, under which circumstances ATP concentrations decrease and its degradation products increase and are released into the cerebrospinal fluid. In this study of alterations in neuronal energy metabolism in meningitis, AMP, IMP, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine and urate were determined by high performance liquid chromatography in the cerebrospinal fluid of 54 children aged between 1 month and 13 years suffering from meningitis (25 viral, 24 bacterial and 5 tuberculous cases) and 63 controls. Compared to the controls, patients with viral meningitis exhibited high concentrations of IMP, adenosine, guanosine, adenine, guanine and xanthine; patients with bacterial meningitis exhibited high concentrations of IMP, inosine, guanosine, adenosine, hypoxanthine, xanthine and urate; and patients with tuberculous meningitis exhibited high concentrations of AMP, guanosine, xanthine and urate. Viral and bacterial cases did not differ significantly for any of the metabolites studied. AMP and urate concentrations were significantly higher in patients with tuberculous cases compared with viral or bacterial meningitis cases.

Indicators of hypoxia in cerebrospinal fluid of hydrocephalic children with suspected shunt malfunction

We used high performance liquid chromatography to determine the concentration of purine metabolites in the cerebrospinal fluid of three hydrocephalic children with a history of shunt malfunction. Hypoxanthine and xanthine levels were high in comparison with controls. We consider these purines to be valuable indicators of disturbance of neuronal metabolism following the sustained rise in intracranial pressure caused by shunt valve malfunction.

The urate and xanthine concentrations in the cerebrospinal fluid in patients with vascular dementia of the Binswanger type, Alzheimer type dementia, and Parkinson's disease

We determined the urate and xanthine concentrations in the cerebrospinal fluid (CSF) in patients with vascular dementia of the Binswanger type (VDBT), Alzheimer type dementia (ATD), and Parkinson's disease (PD). We found that the urate concentration was significantly increased in VDBT patients, but significantly decreased in ATD patients compared with controls. The ratio of the concentrations of uric acid (UCSF) to xanthine (XCSF) in the CSF (UCSF/XCSF) had a significant correlation with the ratio of the UCSF to the urate concentration in serum (U(serum)) (UCSF/U(serum)) in ATD and PD, whereas UCSF/U(serum) increased independently of UCSF/XCSF in VDBT. We concluded that the significant increase in the urate concentration in VDBT is mainly due to an impairment of the blood-brain barrier (BBB), and its significant reduction in ATD may reflect impaired brain metabolism.

Transport of hypoxanthine from plasma to cerebrospinal fluid and vitreous humor in newborn pigs

To determine whether an elevated level of hypoxanthine in cerebrospinal fluid or vitreous humor might reflect a high plasma hypoxanthine concentration, or whether it necessarily represents local tissue hypoxia, we infused hypoxanthine intravenously to normoxemic and normotensive piglets (n = 6). Hypoxanthine was measured in different body fluids using HPLC. During the 8 hours of infusion hypoxanthine increased in plasma (from 30 +/- 6 mumol/l (mean +/- SD) before the infusion to 68 +/- 20 mumol/l at the end of the infusion, p < 0.01), cerebrospinal fluid (CSF) (19 +/- 8 to 43 +/- 9 mumol/l, p < 0.05) and vitreous humor (15 +/- 5 to 30 +/- 6 mumol/l, p < 0.05). After infusion, hypoxanthine values in all three fluids were similar to those seen in pigs after severe hypoxia. Hypoxanthine in vitreous humor and plasma were significantly correlated (r = 0.80, 95% confidence interval 0.47-0.93, p < 0.001). Urinary excretion of hypoxanthine increased almost 40 times from 0.12 +/- 0.14 to 4.6 +/- 2.9 mumol/kg/h indicating that renal excretion of hypoxanthine is not achieved just by passive filtration. We conclude that in newborn piglets hypoxanthine can pass from plasma to CSF and vitreous humor. Thus an increased CSF hypoxanthine concentration is not definite proof that significant cerebral hypoxia has occurred.

Purine metabolites and pyrimidine bases in cerebrospinal fluid of children with simple febrile seizures

Adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine, uric acid and pyrimidine bases were determined in the CSF of 18 children after simple febrile seizures and in a control group. There was no statistically significant difference between the two groups for any of these metabolites. This suggests that simple febrile seizures neither significantly disturb the metabolism of nucleotides, nucleosides or bases, nor significantly deplete neuron adenosine triphosphate ATP levels.

Cerebrospinal fluid calcium, parathyroid hormone, and monoamine and purine metabolites and the blood-brain barrier function in primary hyperparathyroidism

Psychiatric disturbances are common in primary hyperparathyroidism (HPT), but their pathogenesis is essentially unknown. This study deals with cerebrospinal fluid (CSF) calcium homeostasis and its connection with parathyroid hormone (PTH), blood-brain barrier (BBB) function, and central monoamine and purine metabolites in patients with primary HPT. In 22 patients with primary HPT (serum calcium 2.85 +/- 0.21 mmol/l), the CSF concentrations of total and ionized calcium were higher (1.21 +/- 0.08 mmol/l, p less than 0.01, and 1.09 +/- 0.05 mmol/l, p less than 0.001, respectively) than in 11 normocalcemic reference subjects. The values correlated with serum calcium concentration (p less than 0.001) and CSF/serum albumin ratio, a measure of BBB permeability. The latter ratio was elevated in one-third of the patients with HPT, indicating BBB damage. CSF immunoreactive intact PTH was higher in the HPT patients than in the reference group (p less than 0.05), and serum and CSF PTH were positively correlated (p less than 0.05). The CSF levels of the monoamine metabolites 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) were lower, and the level of urate in CSF was higher, in the HPT patients than in the reference subjects, while there were no consistent differences in CSF hypoxanthine or xanthine. CSF 5HIAA correlated inversely with CSF ionized calcium (r = -0.42, p = 0.02). After parathyroid surgery, CSF calcium and urate decreased significantly and CSF monoamine metabolites increased slightly. The decrease in CSF ionized calcium correlated with the alleviation of psychiatric symptoms. The results indicate the importance of increased CSF calcium concentrations in patients with primary HPT and suggest a relation between central calcium regulation and central turnover of monoamines.

Opposite alterations in cerebrospinal fluid uridine after severe cerebral ischemia or intrathecal blood injection

1. Rats which survived hypoglycemia by insulin, hypoxia by 10% O2, or ischemia by carotid ligation and hypotension to 40 mm Hg, evidenced no changes in cerebrospinal fluid (CSF) uridine. Animals which died soon after the above interventions or as a result of KCl-induced cardiac arrest had elevated CSF uridine concentrations. 2. Injection of whole blood or the soluble contents of lysed blood cells into the lateral ventricle of rats reduced CSF uridine to less than one-half normal at 24 hrs but values returned to normal 3 days later. Changes in hypoxanthine resembled those of uridine, but were less dramatic, whereas xanthine concentrations were largely unaltered. Intraventricular injection of plasma or saline did not alter CSF uridine. 3. It seems most likely that low CSF uridine concentrations previously reported in head injury patients may be secondary to the effects of blood cell contents in the cerebrospinal fluid, rather than responses to altered metabolism in neurons or glia cells.

[Metabolism of purine nucleotides in the central nervous system in patients with phosphoribosylpyrophosphate synthetase hyperactivity and neurosensory deafness]

The overactivity of PRPP synthetase is transmitted as a sex-linked abnormality, being characterized by uric acid overproduction and, in some patients, by muscular hypotonia, neurosensitive deafness and/or ataxia. The pathogenesis of these neurologic abnormalities is not yet known. The CSF concentrations of end products of the neuronal metabolism of purines--hypoxanthine for the adenine nucleotides and xanthine for guanine nucleotides--have not been previously studied in patients with overactivity of PRPP synthetase. We have evaluated the plasma and CSF levels of hypoxanthine and xanthine in a 8-year-old male with tophaceous gout and neurosensitive deafness and in his mother, who had gout without neurological involvement. PRPP synthetase overactivity was demonstrated in fibroblast culture; the male was hemizygote and his mother was heterozygotic. In 4 normal individuals, the plasma levels of hypoxanthine and xanthine were 1.7 +/- 0.4 microM and 0.9 +/- 0.2 microM (mean +/- SEM), respectively, while in in CSF they were 3.3 +/- 1.1 microM and 2.0 +/- 0.2 microM. The hemizygote male showed a considerable increase in hypoxanthine level (5.6 microM in plasma and 22.1 microM in CSF); the plasma and CSF xanthine levels were 1.8 and 4.5 microM, respectively. The heterozygotic female showed moderately increased plasma hypoxanthine levels (3.9 and 10.6 microM) and normal xanthine levels (1.3 and 1.8 microM). These results suggest an increase in the degradation of purine nucleotides in the central nervous system of patients with PRPP synthetase overactivity and neurological symptoms. The predominance of hypoxanthine over xanthine may indicate a greater increase of the degradation of adenine rather than guanine nucleotides.

Therapeutic criteria in hydrocephalic children

The xanthine, hypoxanthine, and total oxypurine levels were determined in the CSF of 28 hydrocephalic patients (age from newborn to 2 years) and 8 healthy controls using HPLC. The Evans' index, the mean weekly increase in cranial circumference, and the intracranial pressure were also measured. Of the hydrocephalic patients 13 were self-compensated and the other 15 had a shunt implanted during the course of the study. The mean xanthine, hypoxanthine, and total oxypurine levels in the normal children were 5.20, 5.94, and 11.29 mumol/l, respectively. In the self-compensated hydrocephalics these levels were 5.17, 5.71, and 10.79 mumol/l, respectively. In the noncompensated hydrocephalics, they were 9.90, 9.91, and 19.82 mumol/l. The differences between the latter group and the first two are statistically significant (P less than 0.001). The mean Evans' index and the mean weakly increase in cranial circumference in the self-compensated hydrocephalics were 0.35 and 0.25 cm, respectively. In the noncompensated hydrocephalics, they were 0.55 and 0.95 cm. The differences between the two groups are statistically significant (P less than 0.001). Two weeks after implantation of shunts in the noncompensated cases, the mean xanthine, hypoxanthine, and total oxypurine levels fell to 4.22, 4.57, and 8.80 mumol/l, respectively. These changes are statistically significant (P less than 0.001). We think that the two criteria (clinical and biochemical) are equally useful for the prediction of self-compensation in hydrocephalic children and that the oxypurine values after shunt implantation can be used to monitor progress in noncompensated cases.

Cerebrospinal fluid nucleotide metabolites following short febrile convulsions

Cerebrospinal fluid (CSF) markers of cerebral energy depletion were measured in 32 infants and children following short (less than 10 minutes) febrile convulsions, and in 19 controls. Specific and sensitive indices of high-energy phosphate compound depletion (hypoxanthine, xanthine and uridine) showed no marked changes. Values for patients and febrile controls were significantly higher than for afebrile controls, which is consistent with increased cerebral metabolism in febrile patients. There were no differences in pH, lactate or creatine kinase levels in the CSF of patients and controls. The results suggest that short febrile convulsions are benign and that in the absence of risk factors for the subsequent development of epilepsy, prophylactic anticonvulsant treatment is not indicated.

Cerebrospinal fluid nucleotide metabolites following non-convulsive status epilepticus

The authors studied specific and sensitive indicators of neuronal adenosine triphosphate (ATP) depletion--hypoxanthine, xanthine and uridine levels--in the cerebrospinal fluid (CSF) of nine children during non-convulsive status epilepticus. No evidence of ATP depletion was found and CSF pH and creatine kinase levels were similar to those of controls. Hypoxanthine, xanthine and uridine had a tendency to be low, but this was significant only for xanthine. The authors speculatively link this reduction to a reduction in neuronal protein synthesis. This might be a mechanism whereby non-convulsive status epilepticus could lead to intellectual deterioration and dementia.

Distribution of enprofylline and theophylline between plasma and cerebrospinal fluid

Six patients undergoing diagnostic lumbar myelography were studied with respect to plasma and cerebrospinal fluid (CSF) concentrations of two xanthine drugs--enprofylline and theophylline. Three patients received enprofylline and three patients received theophylline, 200 mg t.i.d., and plasma and CSF were sampled on the morning of the third day of treatment. CSF plasma ratios averaged 0.095 with enprofylline (range of 0.094-0.097) and 0.36 with theophylline (range of 0.35-0.37). The different ratios of the two drugs contrast to their similar plasma protein binding, about 50%. Different lipophilicity or differences with regard to transport out of the CSF may explain the discrepancy.

[Purine transport through the blood-brain barrier in hypoxanthine phosphoribosyltransferase deficiency]

The transfer of purines through the hematoencephalic barrier is poorly understood. Allopurinol inhibits the enzyme xanthine oxidase and increases xanthine and hypoxanthine plasma levels, but it should not increase the cerebrospinal fluid (CSF) levels of these purines owing to the absence of xanthine oxidase in the central nervous system (CNS). In the present study we evaluated the plasma and CSF concentrations of uric acid, hypoxanthine, xanthine and inosine in the baseline state and after 7 days of allopurinol administration (5-10 mg/kg/24 h) in 4 patients with hypoxanthine phosphoribosyltransferase (HPRT) deficiency. The CSF uric acid level was positively correlated with its plasma level (r = 0.93, p less than 0.01). The CSF hypoxanthine and xanthine concentrations were, as a mean, 5 and 2 times higher, respectively, in patients with HPRT deficiency than in 4 control individuals. As hypoxanthine basically comes from adenine nucleotides, while xanthine comes from guanine nucleotides, this finding suggests that in the CNS of patients with HPRT deficiency there is a higher degradation level of adenine nucleotides than of guanine nucleotides. Allopurinol increased plasma concentration of hypoxanthine, xanthine and inosine 4, 10 and 3 times, respectively, in relation to baseline values. In CSF, the mean increase of hypoxanthine and xanthine concentration was 17.5 mumol and 7.7 mumol, respectively, whereas inosine level was unchanged. These results suggest that in HPRT deficiency hypoxanthine and xanthine may be transferred to the brain.

Purine metabolites in the CSF in presenile and senile dementia of Alzheimer type, and in multi infarct dementia

Concentrations of hypoxanthine, xanthine, uric acid and creatinine were measured in CSF of patients suffering form presenile and senile dementia of Alzheimer type (PDAT, SDAT) and multi infarct dementia (MID) and in a reference group of young neurotic patients. There was no difference in hypoxanthine concentration, but there was a marked elevation of xanthine concentration in each dementia group, independent of the type of dementia. There was a significant elevation of uric acid in SDAT and MID but not in PDAT. The concentration of uric acid was higher in MID than in SDAT. There was a higher level of creatinine in the dementia groups, but no difference was seen among the dementia groups. These results are discussed in order to better interpret the etiology and the differentiated diagnosis of the types of dementia.

Determination of rat cerebrospinal fluid concentrations of adenosine, inosine, hypoxanthine, xanthine and uric acid by high performance liquid chromatography

Isocratic reverse-phase high performance liquid chromatography techniques were developed to resolve and quantitate the purine nucleosides adenosine (Ado) and inosine (Ino) and their metabolites hypoxanthine (Hyp), xanthine (Xan), and uric acid (UA) in the cerebrospinal fluid of the rat. The moving phase composition for resolving hypoxanthine, xanthine and uric acid was a 0.22 M, pH 5.8 phosphate buffer. The moving phase composition for resolving adenosine and inosine was a 0.22 M, pH 6.8 phosphate buffer, 7% methanol (v/v) and 2.5 mM tetrabutylammonium phosphate. The observed cerebrospinal fluid concentrations in the rat were: Ado = 35 +/- 9 nM (s.e.m.), Ino = 359 +/- 85 nM, Hyp = 243 +/- 77 nM, Xan = 1340 +/- 423 nM and UA = 6130 +/- 678 nM.

Hypoxanthine, xanthine, urate and creatinine concentration gradients in cerebrospinal fluid

The purine metabolites hypoxanthine, xanthine and urate as well as creatinine were measured in cerebrospinal fluid (CSF) from two groups of patients and a reference sample group. In one of the patient groups lumbar CSF was collected in 2 ml portions until a total volume of 14 ml was withdrawn. Every second portion was analysed for its content of the metabolites in focus. In the other patient group both cisternal CSF and a fixed volume (20 ml) of lumbar CSF were obtained and analysed. An increase in concentration of hypoxanthine, xanthine and creatinine and a decrease in urate concentration was found in the successive CSF specimens. The mean individual increase in hypoxanthine concentration between the first and the last 2 ml portion was as high as 39.6%, while it was lower for xanthine, 21.5%, and creatinine, 6.7%. The decrease in urate concentration was 17.2%. The results from the other patient group were in good agreement with these findings. The concentrations in the cisternal CSF was 162% of that in lumbar CSF for hypoxanthine, 155% for xanthine, 123% for creatinine and 80% for urate. Mechanisms behind inter- and intraindividual differences in gradients are discussed.

The concentrations of xanthine and hypoxanthine in cerebrospinal fluid as therapeutic guides in hydrocephalus

Xanthine, hypoxanthine, and total oxypurine levels were determined in the cerebrospinal fluid of 18 hydrocephalic patients and 8 healthy controls by high-performance liquid chromatography (HPLC). Eight of the hydrocephalic patients were self-compensated and 10 had shunts implanted during the course of the study. The mean xanthine, hypoxanthine, and total oxypurine levels in the normal children were 5.20, 5.94 and 11.29 mumol/l, respectively. In self-compensated hydrocephalics these levels were respectively 6.06, 6.50 and 12.57 mumol/l. In noncompensated hydrocephalics, they were 11.40, 10.79 and 22.19 mumol/l. The differences between the latter group and the first two are statistically significant (P less than 0.001). Fifteen days after implantation of shunts in the noncompensated hydrocephalics, the mean xanthine levels had fallen to 4.61 mumol/l, the mean hypoxanthine levels to 5.03 mumol/l, and the mean total oxypurine levels to 9.64 mumol/l. The change is statistically significant (P less than 0.001). In light of these findings we propose that xanthine, hypoxanthine, and total oxypurine levels be used in cases of hydrocephalus as guides for therapeutic action and to monitor progress.

Studies of biochemical markers in cerebrospinal fluid in patients with meningoencephalitis

Several biochemical markers in the cerebrospinal fluid (CSF) of 120 patients with serous meningoencephalitis (SM) of viral origin were compared with those of 74 patients with viral or bacterial infections accompanied by neck stiffness but no CSF abnormality (i.e., meningism). CSF adenylate kinase was higher (P less than 0.025) in SM and correlated with lactate concentration (r = 0.37; P less than 0.01). CSF hypoxanthine was lower (P less than 0.001) in SM, whereas CSF xanthine was similar in the two conditions. The xanthine/hypoxathine ratio correlated with the CSF leukocyte count (r = 0.32; P less than 0.01), and especially with the mononuclear cell count (r = 0.45; P less than 0.001). CSF adenylate kinase correlated with fever in SM (r = 0.28; P less than 0.01). CSF urate and protein displayed a mutual correlation in both conditions (r = 0.26 and P less than 0.05 for SM; r = 0.55 and P less than 0.001 for meningism). These results support the hypothesis of impaired brain cell metabolism, probably of ischemic nature, in viral meningoencephalitis, causing leakage of adenylate kinase into the CSF, where hypoxanthine may be reutilized by mononuclear leukocytes.

Increased concentration of hypoxanthine in human central cerebrospinal fluid after subarachnoid haemorrhage

The adenine nucleotide metabolites hypoxanthine, xanthine and uric acid were determined by high performance liquid chromatography in cerebrospinal fluid (CSF) from 25 patients with subarachnoid haemorrhage (SAH) and from 26 control subjects. In addition, the haemoglobin and protein levels in the CSF of the patients were determined. In 13 subjects, from which lumbar CSF was collected three, six and nine days after SAH, there was a gradual increase in 8 patients for hypoxanthine and in 3 of the 13 patients for xanthine and uric acid. The mean concentrations were not significantly higher than the controls. In 12 SAH patients, consecutive CSF fractions of 10 ml were collected peroperatively during surgical clipping of aneurysms. The hypoxanthine concentrations increased continuously from lumbar to central CSF samples. Hypoxanthine levels were 6.5 +/- 1.0 microM in lumbar CSF compared to 11.8 +/- 2.3 microM in central CSF (p less than 0.001), while xanthine, uric acid, haemoglobin and protein levels were equally distributed. Furthermore, the SAH patients showed about 3 times higher concentrations of central CSF hypoxanthine (p less than 0.01) and xanthine (p less than 0.05) while that for uric acid was similar compared to all control subjects. Also, as in vitro study showed that the increased concentrations of the adenine nucleotide metabolites could not be caused by degradation of blood components in the subarachnoid space. It is presumed that the increased central CSF concentrations of hypoxanthine that were demonstrated in patients after SAH could be a sensitive marker for brain tissue ischaemia. However, since there was no correlation between the hypoxanthine levels, clinical condition or cerebral vascular diameter, other factors have to be excluded before ischaemia alone could explain the elevated central hypoxanthine levels in patients without major clinical dysfunction after SAH.

Cerebrospinal fluid hypoxanthine and xanthine concentrations as indicators of metabolic damage due to raised intracranial pressure in hydrocephalic children

Intracranial pressure and cerebrospinal fluid hypoxanthine and xanthine concentrations were measured in hydrocephalic children with suspected raised intracranial pressure. There was a highly significant correlation between intracranial pressure and cerebrospinal fluid hypoxanthine and xanthine levels.

Low levels of somatostatin in human CSF mark depressive episodes

Somatostatin-like immunoreactivity was measured in the cerebrospinal fluid (CSF) of 85 inpatients with current or recent episodes of major depressive disorders, diagnosed according to Research Diagnostic Criteria (RDC) as assessed with the Schedule for Affective Disorders and Schizophrenia (SADS). Several biopsychiatric tests were run during the same week of investigation. Results indicate low levels of CSF somatostatin to be a state marker for episodes of depression characterized by sad appearance, feelings of tiredness, insomnia, and subjective inability to acknowledge any external precipitants for the depression. CSF somatostatin was negatively related to platelet monoamine oxidase (MAO) activity; MAO activity appeared to account better for the degree of melancholic features than did somatostatin. The ratio between 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovanillic acid (HVA) in CSF also correlated negatively with somatostatin. A positive relationship was noted between CSF xanthine and somatostatin. There was a highly significant curvilinear correlation between CSF somatostatin and serum TSH concentrations, but no correlations between CSF somatostatin and serum GH or prolactin, or with plasma cortisol before or after dexamethasone.

Simultaneous liquid-chromatographic determination of hypoxanthine, xanthine, urate, and creatinine in cerebrospinal fluid, with direct injection

In this method for simultaneously determining hypoxanthine, xanthine, urate, and creatinine in cerebrospinal fluid, centrifuged sample is directly injected on a reversed-phase liquid-chromatographic column. On elution with potassium phosphate buffer the compounds are quantified by their absorbance at 260 nm. Random error (CV) was between 1.2 and 3.4% and analytical recoveries were 99-104% at physiological concentrations.

Brain purinergic activity linked with depressive symptomatology: hypoxanthine and xanthine in CSF of patients with major depressive disorders

The purine metabolites hypoxanthine and xanthine were analyzed in cerebrospinal fluid (CSF) of 70 patients with major depressive disorders (diagnosed according to Research Diagnostic Criteria) and, for reference, in 26 nonpsychiatric individuals. In the patient group, levels adjusted by analysis of covariance to same sex, age, height, and weight were univariately and multivariately correlated with both depressive subdiagnoses and individual depressive symptoms. Results indicate that raw CSF levels in depressed patients are significantly correlated with the four variables used in adjustment (for hypoxanthine mainly negatively with height; for xanthine mainly positively with age). Hypoxanthine and xanthine both appear to be linked with the expression of depressive symptomatology: lower levels of hypoxanthine are associated with anger and suicidal tendencies, and higher levels are related to memory disturbance; lower xanthine levels characterize patients with subjective feelings of depression, and in patients with higher levels appetite is poor.

Depression and somatosensory evoked potentials: I. Correlations between SEP and monoamine and purine metabolites in CSF

In 32 patients with major depressive disorders diagnosed according to Research Diagnostic Criteria (RDC), somatosensory evoked potentials elicited at four levels of tactile fingertip stimulation were recorded. Four peak-to-baseline amplitudes (P100, N140, P200, and P300) and two peak-to-trough amplitudes (P100-N140 and N140-P200) plus their amplitude/stimulus intensity slopes were selected for analysis. All 12 measures were adjusted to same sex, age, height, and weight. Values were linearly and curvilinearly correlated with adjusted levels of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5HIAA), 3-methoxy-4-hydroxyphenylglycol (MPHG), hypoxanthine, and xanthine in the cerebrospinal fluid (CSF), monoamine and purine metabolites, respectively. Significant negative linear correlations were found between the P300 amplitude and both HVA and hypoxanthine, and between the P200 slope and both 5HIAA and hypoxanthine. A significant positive correlation existed between the N140-P200 slope and 5HIAA. Curvilinear bivariate regressions demonstrated complex topologies of regression surfaces. Neither attention nor benzodiazepine medication were of significant importance in these relationships.

Purine and monoamine metabolites in cerebrospinal fluid: parallel purinergic and monoaminergic activation in depressive illness?

In the cerebrospinal fluid of 38 patients with major depressive disorders the purine metabolites hypoxanthine and xanthine were positively correlated to the monoamine metabolites HVA and 5HIAA (p less than 0.0001). Hypoxanthine was also positively linked to the noradrenaline metabolite MHPG (p less than 0.005). By the use of multiple regression analysis 70% of the variance in hypoxanthine and 51% of the variance in xanthine were explained by HVA and 5HIAA. The scored magnitude of memory disturbance during depression was positively correlated to hypoxanthine, xanthine, HVA, and 5HIAA, while the degree of somatic anxiety as well as worrying was or tended to be negatively correlated to the same biochemical markers. The conspicuous relationship observed between purine and monoamine metabolite concentrations in CSF during depressive illness might indicate a parallel purinergic and monoaminergic activation of the brain. The observation that certain isolated depressive symptoms appear to relate to hypoxanthine/xanthine in CSF is consistent with the hypothesis of a central role of purines in behaviour.

Cerebrospinal fluid concentrations of hypoxanthine, xanthine, uridine and inosine: high concentrations of the ATP metabolite, hypoxanthine, after hypoxia

CSF obtained for clinical purposes from newborn, children and adults has been analysed by high pressure liquid chromatography for hypoxanthine, xanthine, inosine, uridine and urate. Large rises in hypoxanthine and to a lesser extent xanthine occur for about 24 h after hypoxia. High concentrations were associated with later evidence of brain damage or subsequent death. Changes in CSF could be independent of those in plasma. Small or negligible rises were associated with localised and generalised infections including bacterial meningitis, fits, or both. Marked and rapid rises were found after death. These estimations may "predict" the extent of brain damage or brain death.

Oxypurine concentration in the CSF in children with different diseases of the nervous system

Oxypurine analysis was done in the CSF of 190 children with different diseases. The patients could be divided into four groups: Group A, serving as controls, consisted of 56 children suffering from diseases without neurological signs, for example, leukaemia. 16% of them had raised hypoxanthine values greater than 7.5 mumol/l and 32% raised uric acid values greater than 12.0 mumol/l. Group B comprised 97 children suffering from diseases with neurological signs, for example, meningitis. For these patients the frequency of raised hypoxanthine and uric acid values in the CSF was twice as high as in Group A. Group C comprised 31 patients with different forms of cerebral convulsions. Among these patients 52% had raised hypoxanthine and 70% raised uric acid values. The findings of these patients are described in a previous paper (Manzke et al. 1981). Group D comprises 6 patients from whom CSF samples were taken postmortally. All these deceased patients showed extremely high hypoxanthine + xanthine and uric acid concentrations in their CSF.

Increased nucleotide catabolism after cerebral convulsions

Cardiazol induced seizures in rabbits showed that the highest oxypurine concentrations can be detected in the CSF 1 hour after the convulsions. There is a sharp decline continuing until the third hour. After that the CSF values remain nearly constant until the 24th hour being about ten times higher than in the controls. There is a good correlation of these results obtained through the densitometric thin-layer, enzymatic-oxymetric, and HPLC-methods. Creatinine and potassium were raised only during the first two hours postconvulsively. Uracil appeared in the CSF slightly higher at the 1 hour and at the 12 and 24 hour values. A parallel increase of the oxypurine and creatinine concentrations was found in the serum between 30 to 120 minutes postconvulsively. After that the raised serum values decreased slowly to the initial values. CSF samples were examined in 31 children postconvulsively: Hypoxanthine was found to be raised in 8 of 12 patients with severe grand mal seizures, 1 of 6 patients with hypsarrhythmia, 1 of 8 patients with short seizures (less than 2 min) and in all 5 patients with petit mal status. In contrast to these groups the hypoxanthine concentrations was raised only in 2 of 20 children with aseptic meningitis. The difference between the group of children with convulsions and the group of children with aseptic meningitis is significant (p less than 0.005). Also, the frequency of raised uric acid concentration is higher in the group of children with convulsions (70%) than in the group of children with aseptic meningitis (40%); (p less than 0.05).