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

Cerebral white matter oxidation and nitrosylation in young rodents with kaolin-induced hydrocephalus

Hydrocephalus is associated with reduced blood flow in periventricular white matter. To investigate hypoxic and oxidative damage in the brains of rats with hydrocephalus, kaolin was injected into the cisterna magna of newborn 7- and 21-day-old Sprague-Dawley rats, and ventricle size was assessed by magnetic resonance imaging at 7, 21, and 42 days of age. In-situ evidence of hypoxia in periventricular capillaries and glial cells was shown by pimonidazole hydrochloride binding. Biochemical assay of thiobarbituric acid reaction and immunohistochemical detection of malondialdehyde and 4-hydroxy-2-nonenal indicated the presence of lipid peroxidation in white matter. Biochemical assay of nitrite indicated increased nitric oxide production. Nitrotyrosine immunohistochemistry showed nitrosylated proteins in white matter reactive microglia and astrocytes. Activities of the antioxidant enzymes catalase and glutathione peroxidase were not increased, and altered hypoxia-inducible factor 1α was not detected by quantitative reverse transcription-polymerase chain reaction. Cerebral vascular endothelial growth factor expression determined by quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay was not changed, but vascular endothelial growth factor immunoreactivity was increased in reactive astrocytes of hydrocephalic white matter. To determine if nitric oxide synthase is involved in the pathogenesis, we induced hydrocephalus in 7-day-old wild-type and neuronal nitric oxide synthase-deficient mice. At 7 days, the wild-type and mutant mice exhibited equally severe ventriculomegaly and no behavioral differences, although increased glial fibrillary acidic protein was less in the mutant mice. We conclude that hypoxia, via peroxidation and nitrosylation, contributes to brain changes in young rodents with hydrocephalus and that compensatory mechanisms are negligible.

The importance of the measurement of ATP depletion and subsequent cell damage with an estimate of size and nature of the market for a practicable method: a review designed for technology transfer

ATP is the energy currency of cells. ATP depletion is a central process in pathogenesis, in particular ischaemia, hypoxia and hypoglycaemia. ATP depletion in cells can be indirectly measured from the increased concentrations of extracellular hypoxanthine, a central intermediate in the metabolism of ATP. Cell damage secondary to ATP depletion can also be measured from extracellular hypoxanthine. The relevant biochemistry and physiology is briefly reviewed. Since market size is needed for investment decisions that would allow technology transfer, the numbers of hypoxanthine analyses that are clinically justified from the extensive published evidence are calculated per million population from UK, Norwegian and other evidence. The concentration of oxygen in blood is measured to estimate whether mitochondrial oxidative phosphorylation is adequate. Measurements of bicarbonate are used to estimate anaerobic glycolysis. Since the indirect estimation of ATP depletion is a major objective of blood gas and acid-base analyses, the number of such analyses per million population provides a good estimate of potential market size for a more direct method of estimating ATP depletion. A method is required for the rapid, dispersed emergency analyses needed clinically. Routes for method development are indicated. Competition, risks, acceptability, consumer motivation and timetables are indicated for the development phase. There are medicolegal pressures, especially in the USA, for the proposed advances to be widely used.

Cerebrospinal fluid purine metabolites after complex febrile convulsions

Adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine and uric acid were determined in cerebrospinal fluid (CSF) of 15 children after complex febrile seizures (CFS) and in 27 after simple febrile seizures (SFS), and compared with those in a control group of 63 children. There was no statistically significant difference between the groups for any of these metabolites, suggesting that CFS and SFS neither significantly disturb the metabolism of nucleotides, nucleosides or bases nor significantly deplete neuron adenosine triphosphate levels.

Cerebrospinal fluid purine metabolites and pyrimidine bases after brief febrile convulsions

Adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine, uric acid, and pyrimidines bases were determined in cerebrospinal fluid (CSF) of 52 children after simple febrile seizures and in a control group of 63 children. There was no statistically significant difference between the two groups for any of these metabolites, suggesting that simple febrile seizures (SFS) neither significantly disturb the metabolism of nucleotides, nucleosides, or bases nor significantly deplete neuron adenosine ATP levels. Therefore, they do not appear to constitute a threat of neuronal damage.

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.

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.

Concentrations of purine nucleotides and purine and pyrimidine bases in cerebrospinal fluid of neurologically healthy children

The concentrations of the nucleotides AMP and IMP, the nucleosides adenosine, guanosine and inosine, the purine bases adenine, guanine, hypoxanthine and xanthine, urate, and the pyrimidine bases cytosine, thymine and uracil were determined by high performance liquid chromatography in the cerebrospinal fluid of 63 children aged between 1 month and 13 years who showed no sign of neurological disease. The results are compared with those of other authors, and used to establish reference ranges for the above metabolites in the cerebrospinal fluid of children.

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.

Hypoxanthine, xanthine and uridine in body fluids, indicators of ATP depletion

Measurements of hyp, xan and urd in body fluids can provide evidence of energy, ATP, depletion in the body, in organs or in cells. Such information is clinically useful in the many diseases in which cellular energy supplies cannot be maintained like perinatal asphyxia, hydrocephalus and vascular insufficiency in brain, heart, limbs, kidneys or other organs. Similar HPLC methods using reversed-phase C18 columns and quantitation by UV absorption have been employed in a variety of centres to yield almost identical results. These have been assembled in this review to form a series of reference values. The current analytical problems are reviewed. Since concentrations of hyp and xan may alter independently situations are discussed in which separate measurements rather than their summed, total oxypurine concentrations are needed. The biochemistry and physiology underlying the use of such analyses is examined to guide sampling of the appropriate body fluid at a relevant time and to avoid oversimplified interpretation of results as well as unnecessary arguments. Specifically: (1) Intracellular concentrations of hyp and xan are inversely related to adenylate energy change and therefore to the energy currency of the cell ATP. Uridine in tissues is similarly 'controlled'. (2) There is extensive evidence that large increases in hyp, xan and urd in body fluids indicate ATP depletion. (3) Small changes in hyp probably reflect alterations of ATP turnover. (4) Xanthine arises mainly from guanine and can change independently of hyp. (5) Clinically useful information is obtainable from hyp and xan concentrations in CSF, amniotic fluid, urine and plasma. Extensive clinical correlations are reviewed. At present we are in a development phase for which HPLC is ideal but the most efficient way to perform and use such analyses in routine clinical practice remains to be established.

Alterations in cerebrospinal fluid uridine, hypoxanthine, and xanthine in head-injured patients

1. Examination of the cerebrospinal fluid (CSF) of head-injured patients reveals that the concentration of intraventricular xanthine is elevated and that of uridine is decreased relative to those of adult lumbar CSF. 2. No correlations were observed between CSF lactate and CSF hypoxanthine, xanthine, or uridine, suggesting that changes in purine metabolites and the pyrimidine nucleoside do not index similar cellular events as does lactic acid production. 3. Ventricular CSF from hydrocephalic infants had uridine and hypoxanthine concentrations not significantly different from those of normal adult lumbar CSF, but xanthine was significantly elevated. 4. Since uridine has anticonvulsant properties and is a crucial substrate for cerebral metabolism, it may be useful to evaluate this pyrimidine for use in the management of patients with head injury.