Electrochemical sensor based on magnetite graphene oxide/ordered mesoporous carbon hybrid to detection of allopurinol in clinical samples.

Allopurinol (ALO) is a radical scavenging clinical drug, a drug in the treatment of gout, an inhibitor of xanthine oxidase and an effective agent for anti-cancer purposes. The xanthine oxidase is thus essential, and the amount of ALO needs to be controlled more strictly. In this study, a new electrochemical sensor based on magnetite graphene oxide/ordered mesoporous carbon (Fe3O4@GO/OMC) hybrid was prepared and characterized. The results showed sphere shape Fe3O4 nanoparticles with a diameter in the range 17-22 nm on composite. Modification of carbon paste electrode (CPE) with Fe3O4@GO/OMC (Fe3O4@GO/OMC-CPE) allowed the ultrasensitive and selective detection of ALO at oxidation potential of 1.05 V with linear range of 0.05-7 µmol L-1, limit of detection of 47 nmol L-1 and sensitivity of 708 µA mmol-1 L. Also, the results demonstrate that charge transfer at the interface of Fe3O4@GO/OMC hybrid can provide a synergistic effect in comparison with Fe3O4@GO and OMC. The unique surface chemistry of Fe3O4@GO/OMC interface allows π-π stacking and electrostatic interactions with ALO. The advantages are the possibility to regenerate the surface of the sensor, its rapid and easy of production, as well as its applicability for detection of ALO in Tablets and human serum samples, making Fe3O4@GO/OMC-CPE promising interface for bio-electrochemical applications.

Analytical Pitfalls of Therapeutic Drug Monitoring of Thiopurines in Patients With Inflammatory Bowel Disease.

The use of thiopurines in the treatment of inflammatory bowel disease (IBD) can be optimized by the application of therapeutic drug monitoring. In this procedure, 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP) metabolites are monitored and related to therapeutic response and adverse events, respectively. Therapeutic drug monitoring of thiopurines, however, is hampered by several analytical limitations resulting in an impaired translation of metabolite levels to clinical outcome in IBD. Thiopurine metabolism is cell specific and requires nucleated cells and particular enzymes for 6-TGN formation. In the current therapeutic drug monitoring, metabolite levels are assessed in erythrocytes, whereas leukocytes are considered the main target cells of these drugs. Furthermore, currently used methods do not distinguish between active nucleotides and their unwanted residual products. Last, there is a lack of a standardized laboratorial procedure for metabolite assessment regarding the substantial instability of erythrocyte 6-TGN. To improve thiopurine therapy in patients with IBD, it is necessary to understand these limitations and recognize the general misconceptions in this procedure.

Flow cytometric method for estimation of 5-bromo-2´-deoxyuridine content in rat serum.

Labelling of DNA in replicating cells using 5-bromo-2´-deoxyuridine (BrdU) is widely used, however the rapid clearance and metabolisation of BrdU in the living organism is a critical issue. Although the pharmacokinetic of BrdU in experimental animals is empirically approximated, the exact time-curve remains unknown. Here we present novel method for estimation of the BrdU content in the blood serum. The application is based on the in vitro cocultivation of tumour cells with the examined serum and the subsequent quantification of the incorporated BrdU in the DNA using flow cytometry analysis. Our results demonstrate that this approach can quantify the BrdU concentration in serum at 1 micromol.dm(-3) and might represent an attractive alternative to conventional chromatographic analysis. The employment of tumour cells as "detectors" of the BrdU content in serum provides an advantage over high pressure liquid chromatography (HPLC), as this approach allows us to approximate not only the concentration of BrdU, but also to determine, whether BrdU is present in the blood serum in effective concentration to reliable label all cells undergoing the S-phase of the cell cycle. The presented application might be a helpful tool for studies on pharmacokinetics of BrdU or other thymidine analogues when testing various administration routes or protocols.

Factors affecting exposure to nicotine and carbon monoxide in adult cigarette smokers.

Exposure to cigarette smoke among smokers is highly variable. This variability has been attributed to differences in smoking behavior as measured by smoking topography, as well as other behavioral and subjective aspects of smoking. The objective of this study was to determine the factors affecting smoke exposure as estimated by biomarkers of exposure to nicotine and carbon monoxide (CO). In a multi-center cross-sectional study of 3585 adult smokers and 1077 adult nonsmokers, exposure to nicotine and CO was estimated by 24h urinary excretion of nicotine and five of its metabolites and by blood carboxyhemoglobin, respectively. Number of cigarettes smoked per day (CPD) was determined from cigarette butts returned. Puffing parameters were determined through a CreSS® micro device and a 182-item adult smoker questionnaire (ASQ) was administered. The relationship between exposure and demographic factors, smoking machine measured tar yield and CPD was examined in a statistical model (Model A). Topography parameters were added to this model (Model B) which was further expanded (Model C) by adding selected questions from the ASQ identified by a data reduction process. In all the models, CPD was the most important and highest ranking factor determining daily exposure. Other statistically significant factors were number of years smoked, questions related to morning smoking, topography and tar yield categories. In conclusion, the models investigated in this analysis, explain about 30-40% of variability in exposure to nicotine and CO.

Characterization of the interactive effects of glycine and D-cycloserine in men: further evidence for enhanced NMDA receptor function associated with human alcohol dependence.

Reduced responses to N-methyl-D-aspartate (NMDA) glutamate receptor antagonists in alcohol-dependent animals and humans provided evidence that chronic alcohol consumption increased NMDA receptor function. To further probe alterations in NMDA glutamate receptor function associated with human alcohol dependence, this study examined the interactive effects of agents acting at the glycine(B) coagonist site of the NMDA receptor. In doing so, it tested the hypothesis that raising brain glycine concentrations would accentuate the antagonist-like effects of the glycine(B) partial agonist, D-cycloserine (DCS). Twenty-two alcohol-dependent men and 22 healthy individuals completed 4 test days, during which glycine 0.3 g/kg or saline were administered intravenously and DCS 1000 mg or placebo were administered orally. The study was conducted under double-blind conditions with randomized test day assignment. In this study, DCS produced alcohol-like effects in healthy subjects that were deemed similar to a single standard alcohol drink. The alcohol-like effects of DCS were blunted in alcohol-dependent patients, providing additional evidence of increased NMDA receptor function in this group. Although glycine administration reduced DCS plasma levels, glycine accentuated DCS effects previously associated with the NMDA receptor antagonists, ketamine and ethanol. Thus, this study provided evidence that raising glycine levels accentuated the NMDA receptor antagonist-like effects of DCS and that alcohol-dependent patients showed tolerance to these DCS effects.

Hydrophilic interaction liquid chromatography-APCI-mass spectrometry determination of 5-fluorouracil in plasma and tissues.

A simple and fast analytical method using hydrophilic interaction liquid chromatography (HILIC) coupled with mass spectrometry was developed to analyse 5-fluorouracil (5-FU) in plasma and tissues. The HILIC system overcomes problems reported in obtaining satisfactory retention of 5-FU with other types of HPLC systems. After addition of internal standard (IS) (5-Chlorouracil (5-CU)), plasma proteins were precipitated with acetonitrile, and tissue samples homogenised with a micro-dismembrator. The analysis was performed using a polymer-based column (Ashaipak NH2) and the compounds were eluted under gradient conditions at 1 ml/min using a mobile phase containing a mixture of ammonium formate and acetonitrile. MS detection used a API 4000 mass spectrometry with heated nebulizer source and multiple reaction monitoring operated in the negative ion mode. The mass transitions of 5-FU and its internal standard were 129 m/z-->42m/z and 145 m/z-->42 m/z, respectively. The lower limits of quantitation in plasma and tissues were about 5 ng/ml and 10 ng/g, respectively, using 25 microl of plasma and 50mg of tissue. Good linearity, accuracy and precision were obtained in all matrices tested. The suitability and robustness of the method for in vivo samples were confirmed by analysis of mouse plasma, muscle and tumour from animals dosed with 5-FU.

Quantification of a novel retinoic acid metabolism inhibitor, 4-(1H-imidazol-1-yl)retinoic acid (VN/14-1RA) and other retinoids in rat plasma by liquid chromatography with diode-array detection.

A simple reversed phase high performance liquid chromatographic (HPLC) method was developed for the separation and quantification of a novel retinoic acid metabolism inhibitor, 4-(1H-imidazol-1-yl)retinoic acid (VN/14-1RA), and other retinoids in rat plasma. VN/14-1RA, alone or in combination with ATRA, is effective at inhibiting the proliferation of prostate and breast cancer cell lines in vitro. Aliquots of rat plasma were spiked with the retinoids followed by addition of acetonitrile for precipitation of plasma proteins. The decanted supernatant was evaporated under a stream of nitrogen and reconstituted in acetonitrile. Analysis was accomplished by injection of an aliquot of the reconstituted sample into an HPLC system consisting of a Zorbax Rx-C18 column and a diode array detector. A mobile phase composed of ammonium acetate (0.1 M), acetic acid solution (2% (v/v)) and methanol at a flow rate of 1.0 mL/min was used for gradient elution. The recoveries for all compounds ranged from 65 to 85% regardless of the concentrations examined. The HPLC assay was linear over the range 0.10-5.0 microg/mL (CV < 10%) with a limit of quantification of 100 ng/mL for VN/14-1RA. A one-compartment model with apparent first-order elimination was used to describe the plasma concentration-time profile for VN/14-1RA after intravenous administration. The mean terminal elimination half-life (t(1/2)) was 19.0 +/- 3.2 min. This HPLC method is useful for the analysis and evaluation of the pharmacokinetics of VN/14-1RA in rats.

The predictive value of serum 1,5-anhydro-D-glucitol in pregnancies at increased risk of gestational diabetes mellitus and gestational impaired glucose tolerance.

The objective of the study was to determine the efficacy of 1,5-anhydro-D-glucitol (1,5 AG) for the prediction of gestational diabetes and gestational impaired glucose tolerance (GIGT). One hundred and eighty-five pregnant women with epidemiological risk factors of gestational diabetes or GIGT underwent 75 g oral glucose tolerance test and plasma 1,5 AG assay at 26 to 28 weeks of gestation. There was no significant difference in plasma 1,5 AG either before or after an oral glucose load. The area under the receiver operator characteristic curve for 1,5 AG was only 0.485 which implies that 1,5 AG is a poor predictor of GIGT or gestational diabetes.

Influence of D-cycloserine on the anticonvulsant activity of some antiepileptic drugs against audiogenic seizures in DBA/2 mice.

D-Cycloserine (DCS; 1-100 mg/kg, intraperitoneally (i.p.)) was able to antagonise the audiogenic seizures in DBA/2 mice in a dose-dependent manner. DCS, 2.5 mg/kg i.p. did not significantly affect the occurrence of audiogenic seizures in DBA/2 mice, but potentiated the anticonvulsant activity of carbamazepine, diazepam, felbamate, lamotrigine, phenytoin, phenobarbital and valproate against sound-induced seizures in DBA/2 mice. The degree of potentiation induced by DCS was greatest for diazepam, phenobarbital, phenytoin and valproate, less for carbamazepine and least for lamotrigine and felbamate. The increase in anticonvulsant activity was usually associated with a comparable increase in motor impairment. However, the therapeutic index of the combined treatment of the above drugs+DCS, was more favourable than the same drugs+saline with the exception of DCS+carbamazepine and DCS+lamotrigine. Since DCS did not significantly influence the total and free plasma levels of the anticonvulsant drugs studied, pharmacokinetic interactions, in terms of plasma levels, are not probable. The possibility that DCS can modify the clearance from the brain of the anticonvulsant drugs studied cannot be excluded. DCS did not significantly affect the hypothermic effects of the anticonvulsants tested. In conclusion, DCS potentiates the anticonvulsant action of some classical antiepileptic drugs, most notably diazepam, phenobarbital, phenytoin and valproate.

Intracellular studies of the nucleoside reverse transcriptase inhibitor active metabolites: a review.

Nucleoside reverse transcriptase inhibitors (NRTIs) plasma concentrations do not correlate with clinical efficacy or toxicity. These agents need to be phosphorylated to become active against HIV-infection. Thus, the characterization of the NRTIs intracellular metabolite pharmacological parameters will provide a better understanding that could lead to the development of more rational dose regimens in the HIV-infected population. Furthermore, intracellular measurements of NRTIs may provide a better marker with respect to clinical efficacy and toxicity than plasma concentrations. Thus, in this article we review the latest information regarding the intracellular pharmacological parameters of zidovudine (ZDV) and lamivudine (3TC) active metabolites in HIV-infected patients including the results from our recent clinical studies. We will start the discussion with ZDV and 3TC clinical efficacy, followed by systemic pharmacokinetics studies. We will then discuss the in vitro and in vivo intracellular studies with particular emphasis in the method development to measure these metabolites and we will conclude with the most current data from our clinical trials.

Prediction of in vivo drug-drug interactions based on mechanism-based inhibition from in vitro data: inhibition of 5-fluorouracil metabolism by (E)-5-(2-Bromovinyl)uracil.

The fatal drug-drug interaction between sorivudine, an antiviral drug, and 5-fluorouracil (5-FU) has been shown to be caused by a mechanism-based inhibition. In this interaction, sorivudine is converted by gut flora to (E)-5-(2-bromovinyl)uracil (BVU), which is metabolically activated by dihydropyrimidine dehydrogenase (DPD), and the activated BVU irreversibly binds to DPD itself, thereby inactivating it. In an attempt to predict this interaction in vivo from in vitro data, inhibition of 5-FU metabolism by BVU was investigated by using rat and human hepatic cytosol and human recombinant DPD. Whichever enzyme was used, increased inhibition was observed that depended on the preincubation time of BVU and enzyme in the presence of NADPH and BVU concentration. The kinetic parameters obtained for inactivation represented by k(inact) and K'(app) were 2.05 +/- 1.52 min(-1), 69.2 +/- 60.8 microM (rat hepatic cytosol), 2.39 +/- 0.13 min(-1), 48.6 +/- 11.8 microM (human hepatic cytosol), and 0.574 +/- 0.121 min(-1), 2.20 +/- 0.57 microM (human recombinant DPD). The drug-drug interaction in vivo was predicted quantitatively based on a physiologically based pharmacokinetic model, using pharmacokinetic parameters obtained from the literature and kinetic parameters for the enzyme inactivation obtained in the in vitro studies. In rats, DPD was predicted to be completely inactivated by administration of BVU and the area under the curve of 5-FU was predicted to increase 11-fold, which agreed well with the reported data. In humans, a 5-fold increase in the area under the curve of 5-FU was predicted after administration of sorivudine, 150 mg/day for 5 days. Mechanism-based inhibition of drug metabolism is supposed to be very dangerous. We propose that such in vitro studies should be carried out during the drug-developing phase so that in vivo drug-drug interactions can be predicted.

Intracellular studies of the nucleoside reverse transcriptase inhibitor active metabolites: a review

Nucleoside reverse transcriptase inhibitors (NRTIs) plasma concentrations do not correlate with clinical efficacy or toxicity. These agents need to be phosphorylated to become active against HIV-infection. Thus, the characterization of the NRTIs intracellular metabolite pharmacological parameters will provide a better understanding that could lead to the development of more rational dose regimens in the HIV-infected population. Furthermore, intracellular measurements of NRTIs may provide a better marker with respect to clinical efficacy and toxicity than plasma concentrations. Thus, in this article we review the latest information regarding the intracellular pharmacological parameters of zidovudine (ZDV) and lamivudine (3TC) active metabolites in HIV infected patients including the results from our recent clinical studies. We will start the discussion with ZDV and 3TC clinical efficacy, followed by systemic pharmacokinetics studies. We will then discuss the in vitro and in vivo intracellular studies with particular emphasis in the method development to measure these metabolites and we will conclude with the most current data from our clinical trials.

Patterns of cerebrospinal fluid catechols support increased central noradrenergic responsiveness in aging and Alzheimer's disease.

BACKGROUND: High cerebrospinal fluid (CSF) norepinephrine (NE) concentrations in aging and Alzheimer's disease (AD) could reflect decreased NE clearance from central nervous system (CNS) extracellular fluid or increased release of NE into CNS extracellular fluid. Measuring CSF concentrations of the intraneuronal NE metabolite dihydroxyphenylglycol (DHPG), an estimate of NE clearance, and the NE precursor dihydroxyphenylacetic acid (DOPA), an estimate of NE biosynthesis, can help differentiate these mechanisms. METHODS: NE, DHPG, and DOPA were determined by HPLC in CSF and plasma obtained following yohimbine, clonidine, and placebo. Ten AD, 10 older, and 11 young subjects were studied. RESULTS: CSF DOPA following yohimbine was higher in older and AD than in young subjects. CSF DHPG did not differ among groups. Plasma DOPA following yohimbine was higher in AD than in young subjects. CONCLUSIONS: During alpha-2 adrenoreceptor blockade in both aging and AD, there are increased responses of CNS NE biosynthesis and release with unchanged CNS NE clearance. This pattern is consistent with partial loss of CNS noradrenergic neurons with compensatory activation of remaining CNS noradrenergic neurons. Given the marked loss of locus coeruleus (LC) noradrenergic neurons in AD, achievement of high CSF NE suggests particularly prominent compensatory activation of remaining LC neurons in this disorder.

D-cycloserine increases positive symptoms in chronic schizophrenic patients when administered in addition to antipsychotics: a double-blind, parallel, placebo-controlled study.

A hypofunction of the glutamatergic system and NMDA receptors in schizophrenia has been hypothesized. Therefore, stimulation of these receptors could be of benefit to patients with schizophrenia. D-cycloserine has been used for this purpose. This study reports the effects of 100 mg D-cycloserine, when added to typical antipsychotics in chronic schizophrenic patients exhibiting prominent negative symptoms, using a placebo-controlled, double-blind, parallel, design. D-cycloserine slightly worsened psychotic symptoms and general psychopathology as compared to placebo. D-cycloserine failed to change negative symptoms and had no effect on extrapyramidal symptoms. The exacerbation of schizophrenic symptoms may be explained by the antagonistic effects of this dose of D-cycloserine at the glycine recognition site of the NMDA receptor due to competition with the endogenous agonist glycine. Another explanation for the increase in psychopathology may be an interaction with the effects of antipsychotics on NMDA mediated neurotransmission. Thus, D-cycloserine in this study did not ameliorate schizophrenic symptoms. However, the fact that they actually worsened suggests that NMDA systems may be involved in the pathogenesis of schizophrenia. Further placebo-controlled studies with lower dosages of D-cycloserine, preferably in drug-free patients, are necessary to evaluate if D-cycloserine is of use for the treatment of patients with schizophrenia.

Determination of 6-thioguanine and 6-methylmercaptopurine metabolites in renal transplantation recipients and patients with glomerulonephritis treated with azathioprine.

The metabolism of azathioprine (AZA) was studied by monitoring the concentrations of red blood cell (RBC) 6-thioguanine nucleotides (6-TGN) and of 6-methylmercaptopurine metabolites (6-mMP) in 27 renal transplantation recipients and in 10 patient subjects with glomerulonephritis (GN). Concentrations of 6-TGNs and 6-mMP metabolites were measured using high-performance liquid chromatography (HPLC). Six patients from the group of renal transplantation recipients were also administered allopurinol. Median values of RBC 6-TGN and of 6-mMP metabolites concentrations in 21 renal transplantation recipients (without allopurinol) were 122 pmol/8x10(8) RBCs (range, <60-298) and 280 pmol/8x10(8) RBC (range, <150-1330), respectively; there was no correlation between concentrations of 6-TGN and of 6-mMP metabolites. The group of 21 renal transplantation recipients received different AZA doses (100 or 50 mg/d) related to clinical symptoms of AZA intolerance. The median values of 6-TGN concentrations in these subgroups were 131 and 122 pmol/8x10(8) RBCs and were not significantly different. Median values of 6-TGN concentrations in patients given allopurinol were significantly higher, despite AZA dose reduction, compared with the group without allopurinol and were equal to 363 and 122 pmol/8x10(8) RBC, p < 0.004, respectively. No significant differences were found between the concentrations of 6-mMP metabolites in either group. In the group of renal transplantation recipients, a significant correlation between white blood cell (WBC) count and 6-TGN concentration was established (r(s) = -0.59, p < 0.005). In the group of GN patients, the median values of 6-TGN and of 6-mMP metabolites concentrations were 108 pmol/8x10(8) RBCs (range, 0-297) and 420 pmol/8x10(8) RBC (range, 0-1440), respectively. There were no significant correlations between either the WBC count and 6-TGN concentrations or between 6-TGN concentrations and 6-mMP metabolites. We expect the results of our study to provide indications for better individualization of AZA therapy.

First-pass metabolism of 5-fluorouracil in rats.

The first-pass metabolism of 5-fluorouracil has been investigated in rats to compare systemic bioavailability after administration by different routes, the bioavailability after intravenous bolus administration being defined as unity. Bioavailability after oral administration (F(po)) was compared with that after intraintestinal administration into the closed loop (F(loop)) in conscious rats. F(po) was very low and variable (0.28 +/- 0.30, mean +/- s.d.), in agreement with earlier studies in man, but comparable with F(loop) (0.33 +/- 0.05), suggesting insignificant loss of 5-fluorouracil by degradation in the gastrointestinal lumen or by faecal excretion. The bioavailability after intraportal vein administration (F(ipv)) was compared with F(loop) in rats anaesthetized with pentobarbital, anaesthesia being used to maintain a stable portal drug infusion that mimics the sustained input of drug into the portal blood flow after intra-intestinal administration. F(ipv) was smaller than unity (0.68 +/- 0.03), suggesting significant hepatic first-pass metabolism, but higher than F(loop) (0.31 +/- 0.10), suggesting significant first-pass metabolism in the intestinal mucosa. The intestinal bioavailability for passage through the epithelial mucosa (Fi) was estimated, from the ratio of F(loop) to F(ipv) to be 0.46. The study revealed that both the liver and intestinal mucosa are responsible for the extensive first-pass metabolism of 5-fluorouracil after oral administration. This first-pass metabolism might be similar to that in man, in which the oral bioavailability is reportedly similar to that in the rats used in this study. The findings in this study should be of help in monitoring ways of improving oral 5-fluorouracil therapy.

Derivatization of 5-fluorouracil with 4-bromomethyl-7-methoxycoumarin for determination by liquid chromatography-mass spectrometry.

A robust new analytical method has been developed for the determination of 5-fluorouracil (5-FU) in human plasma samples using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The method is based on a liquid-liquid extraction procedure, precolumn derivatization, reversed-phase HPLC separation, and detection using atmospheric pressure chemical ionization and selected reaction monitoring. The derivatization agent used was 4-bromomethyl-7-methoxycoumarin. The internal standard for the assay procedure was a stable isotope labeled analog of 5-FU. The lower limit of quantitation was 1.0 ng/mL using 500 microL aliquots of plasma. Sample throughput on the mass spectrometer was approximately 17 samples/h (3.5 min/sample). The method was fully validated. The recovery of 5-FU averaged 76.1%. The accuracy of the assay, assessed from quality control samples, ranged from 99.1% to 104.3% (% theoretical). The overall interassay precision (% RSD) was 2.7%, and the intraassay precision (% RSD) ranged from 1.5% to 3.9%. The derivatized samples were found to be stable under sample analysis conditions and during refrigerator storage. The method was specific for the determination of 5-FU.

Effect of allopurinol on postasphyxial free radical formation, cerebral hemodynamics, and electrical brain activity.

OBJECTIVE: Free radical-induced postasphyxial reperfusion injury has been recognized as an important cause of brain tissue damage. We investigated the effect of high-dose allopurinol (ALLO; 40 mg/kg), a xanthine-oxidase inhibitor and free radical scavenger, on free radical status in severely asphyxiated newborns and on postasphyxial cerebral perfusion and electrical brain activity. METHODS: Free radical status was assessed by serial plasma determination of nonprotein-bound iron (microM), antioxidative capacity, and malondialdehyde (MDA; microM). Cerebral perfusion was investigated by monitoring changes in cerebral blood volume (delta CBV; mL/100 g brain tissue) with near infrared spectroscopy; electrocortical brain activity (ECBA) was assessed in microvolts by cerebral function monitor. Eleven infants received 40 mg/kg ALLO intravenously, and 11 infants served as controls (CONT). Plasma nonprotein-bound iron, antioxidative capacity, and MDA were measured before 4 hours, between 16 and 20 hours, and at the second and third days of age. Changes in CBV and ECBA were monitored between 4 and 8, 16 and 20, 58 and 62, and 104 and 110 hours of age. RESULTS: Six CONT and two ALLO infants died after neurologic deterioration. No toxic side effects of ALLO were detected. Nonprotein-bound iron (mean +/- SEM) in the CONT group showed an initial rise (18.7 +/- 4.6 microM to 21.3 +/- 3.4 microM) but dropped to 7.4 +/- 3.5 microM at day 3; in the ALLO group it dropped from 15.5 +/- 4.6 microM to 0 microM at day 3. Uric acid was significantly lower in ALLO-treated infants from 16 hours of life on. MDA remained stable in the ALLO group, but increased in the CONT group at 8 to 16 hours versus < 4 hours (mean +/- SEM; 0.83 +/- 0.31 microM vs 0.50 +/- 0.14 microM). During 4 to 8 hours, delta CBV-CONT showed a larger drop than delta CBV-ALLO from baseline. During the subsequent registrations CBV remained stable in both groups. ECBA-CONT decreased, but ECBA-ALLO remained stable during 4 to 8 hours of age. Neonates who died had the largest drops in CBV and ECBA. CONCLUSION: This study suggests a beneficial effect of ALLO treatment on free radical formation, CBV, and electrical brain activity, without toxic side effects.