Effects of ß-alanine administration on selected parameters of oxidative stress and phosphoryltransfer network in cerebral cortex and cerebellum of rats.

ß-Alanine is a ß-amino acid derivative of the degradation of pyrimidine uracil and precursor of the oxidative substrate acetyl-coenzyme A (acetyl-CoA). The accumulation of ß-alanine occurs in ß-alaninemia, an inborn error of metabolism. Patients with ß-alaninemia may develop neurological abnormalities whose mechanisms are far from being understood. In this study we evaluated the effects of ß-alanine administration on some parameters of oxidative stress and on creatine kinase, pyruvate kinase, and adenylate kinase in cerebral cortex and cerebellum of 21-day-old rats. The animals received three peritoneal injections of ß-alanine (0.3 mg /g of body weight) and the controls received the same volume (10 µL/g of body weight) of saline solution (NaCl 0.85 %) at 3 h intervals. CSF levels of ß-alanine increased five times, achieving 80 µM in the rats receiving the amino acid. The results of ß-alanine administration in the parameters of oxidative stress were similar in both tissues studied: reduction of superoxide dismutase activity, increased oxidation of 2',7'-dihydrodichlorofluorescein, total content of sulfhydryl and catalase activity. However, the results of the phosphoryltransfer network enzymes were similar in all enzymes, but different in the tissues studied: the ß-alanine administration was able to inhibit the enzyme pyruvate kinase, cytosolic creatine kinase, and adenylate kinase activities in cerebral cortex, and increase in cerebellum. In case this also occurs in the patients, these results suggest that oxidative stress and alteration of the phosphoryltransfer network may be involved in the pathophysiology of ß-alaninemia. Moreover, the ingestion of ß-alanine to improve muscular performance deserves more attention in respect to possible side-effects.

Beta-alanine and beta-aminoisobutyric acid levels in two siblings with dihydropyrimidinase deficiency.

Dihydropyrimidinase (DHP) deficiency is an inborn error of the pyrimidine degradation pathway, affecting the hydrolytic ring opening of the dihydropyrimidines. In two siblings with a complete DHP deficiency and a variable clinical presentation, a normal concentration of beta-alanine and strongly decreased levels of beta-aminoisobutyric acid were observed in plasma, urine and CSF. No major differences were observed for the concentrations of the beta-amino acids in plasma and urine between the symptomatic and asymptomatic sibling. Thus, the relevance of the shortage of beta-aminoisobutyric acid for the onset of a clinical phenotype in patients with DHP deficiency remains to be established.

beta-Ureidopropionase deficiency: an inborn error of pyrimidine degradation associated with neurological abnormalities.

beta-Ureidopropionase deficiency is an inborn error of the pyrimidine degradation pathway, affecting the cleavage of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid. In this study, we report the elucidation of the genetic basis underlying a beta-ureidopropionase deficiency in four patients presenting with neurological abnormalities and strongly elevated levels of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid in plasma, cerebrospinal fluid and urine. No beta-ureidopropionase activity could be detected in a liver biopsy obtained from one of the patients, which reflected the complete absence of the beta-ureidopropionase protein. Analysis of the beta-ureidopropionase gene (UPB1) of these patients revealed the presence of two splice-site mutations (IVS1-2A>G and IVS8-1G>A) and one missense mutation (A85E). Heterologous expression of the mutant enzyme in Escherichia coli showed that the A85E mutation resulted in a mutant beta-ureidopropionase enzyme without residual activity. Our results demonstrate that the N-carbamyl-beta-amino aciduria in these patients is due to a deficiency of beta-ureidopropionase, which is caused by mutations in the UPB1 gene. Furthermore, an altered homeostasis of beta-aminoisobutyric acid and/or increased oxidative stress might contribute to some of the clinical abnormalities encountered in patients with a beta-ureidopropionase deficiency. An analysis of the presence of the two splice site mutations and the missense mutation in 95 controls identified one individual who proved to be heterozygous for the IVS8-1G>A mutation. Thus, a beta-ureidopropionase deficiency might not be as rare as is generally considered.

New insights in dihydropyrimidine dehydrogenase deficiency: a pivotal role for beta-aminoisobutyric acid?

DPD (dihydropyrimidine dehydrogenase) constitutes the first step of the pyrimidine degradation pathway, in which the pyrimidine bases uracil and thymine are catabolized to beta-alanine and the R-enantiomer of beta-AIB (beta-aminoisobutyric acid) respectively. The S-enantiomer of beta-AIB is predominantly derived from the catabolism of valine. It has been suggested that an altered homoeostasis of beta-alanine underlies some of the clinical abnormalities encountered in patients with a DPD deficiency. In the present study, we demonstrated that only a slightly decreased concentration of beta-alanine was present in the urine and plasma, whereas normal levels of beta-alanine were present in the cerebrospinal fluid of patients with a DPD deficiency. Therefore the metabolism of beta-alanine-containing peptides, such as carnosine, may be an important factor involved in the homoeostasis of beta-alanine in patients with DPD deficiency. The mean concentration of beta-AIB was approx. 2-3-fold lower in cerebrospinal fluid and urine of patients with a DPD deficiency, when compared with controls. In contrast, strongly decreased levels (10-fold) of beta-AIB were present in the plasma of DPD patients. Our results demonstrate that, under pathological conditions, the catabolism of valine can result in the production of significant amounts of beta-AIB. Furthermore, the observation that the R-enantiomer of beta-AIB is abundantly present in the urine of DPD patients suggests that significant cross-over exists between the thymine and valine catabolic pathways.

Combined method for the determination of gamma-aminobutyric and beta-alanine in cerebrospinal fluid by stable isotope dilution mass spectrometry.

A previously described method for the determination of GABA in CSF has been expanded to include both GABA and beta-ALA, using a single GC-MS analysis. A stable isotope labelled internal standard for beta-ALA was synthesised to achieve accurate quantification. This new combined method expands the diagnostic power compared to an isolated GABA measurement. Control values for free and total GABA and free and total beta-ALA are described. Age <2 years: free GABA 0.017-0.067 microM, total GABA 4.2-13.4 microM; free beta-ALA 0.049-0.11 microM, total beta-ALA 2.1-4.6 microM. Age >2 years: free GABA 0.032-0.17 microM, total GABA 3.3-12.2 microM; free beta-ALA 0.021-0.058 microM, total beta-ALA 0.91-3.5 microM.

Neurotoxicity of panipenem/betamipron, a new carbapenem, in rabbits: correlation to concentration in central nervous system.

The neurotoxic potential of panipenem/betamipron (PAPM/BP), a new carbapenem antibiotic, was compared with that of imipenem/cilastatin (IPM/CS). The drug concentration in cerebrospinal fluid (CSF) at the onset of epileptogenic electroencephalographic (EEG)-activity and the drug distribution into the central nervous system (CNS) were evaluated. Epileptogenic reactions correlated well with drug levels in CSF, but not with drug levels in circulating plasma. The concentration of PAPM in CSF at the onset of epileptogenic EEG-activity was almost twice that of IPM, suggesting that neurotoxic activity of PAPM is about half that of IPM. In addition, in terms of incidence percent for the epileptogenic EEG-activity, PAPM/BP was found to be less toxic than IPM/CS within the dose of 1.0-1.2 g/kg. Concentrations of PAPM in CSF and brain extracellular fluid after PAPM/BP i.v. infusion were comparable with those of IPM after IPM/CS infusion, indicating the similar characteristics of distribution into the CNS for the two antibiotics. From these results of pharmacologic effects and drug distributions, it is suggested that the neurotoxicity of PAPM/BP is less than half that of IPM/CS.

[Studies on efficacy and safety of panipenem/betamipron against infections in pediatrics and on its movement to cerebrospinal fluid including cases of penicillin-resistant Streptococcus pneumoniae meningitis].

The efficacy and the safety of panipenem/betamipron (PAPM/BP), a new carbapenem antibiotic against infections in pediatrics were studied. The obtain results are summarized as follows. 1. The transfer of PAPM/BP to cerebrospinal fluid (CSF) was studied in 2 cases of purulent meningitis. The PAPM/BP levels in CSF in a dose 26.1 mg/kg peaked at 3.21 micrograms/ml on sampling 30 minutes after administration, followed by decreasing gradually with the improvement in clinical symptoms and came to 0.86 micrograms/ml on the 12th day (30 minutes after administration). 2. PAPM/BP at dose levels of 50 mg/kg to 69 mg/kg a day (daily doses of 104 mg/kg, 175 mg/kg 4 times a day for 2 cases of purulent meningitis) was administered by intravenous drip infusion 3 times daily for 4 to 15 days to 2 cases of purulent meningitis (including 1 case of penicillin-resistant Streptococcus penumoniae meningitis), 3 cases of pneumonia, 2 cases of phlegmon, 2 cases of periproctal abscess and 2 cases of urinary tract infections for a total of 11 cases. As results, all the cases showed good responses including 5 excellent and 6 good responses. Bacteriological efficacies in all of the 9 eligible cases were assessed as "eradicated". 3. As for the safety, an increase in the platelet count and slight evaluation of GOT and GPT were seen in 1 case as abnormal changes in the laboratory findings, although no side-effect was observed. 4. The results above show that PAPM/BP is useful for the treatment of general infections in pediatrics and that a daily dose of about 60 mg/kg given in 3 divided doses in effective enough.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical evaluation of panipenem/betamipron in pediatrics].

Studies were carried out on the clinical efficacy of panipenem/betamipron (PAPM/BP) against bacterial infections. The results are summarized as follows: 1. PAPM/BP were administered to total 21 patients (7 cases of pneumonia, 1 case of bronchitis, 3 cases of cellulitis, 2 cases of purulent lymphadenitis, 2 cases of otitis media, 1 case of purulent parotitis, 1 case of sinusitis, 1 case of mastoiditis, 2 cases of urinary tract infection and 1 case of purulent meningitis) by drip intravenous injection. 2. Clinical responses of PAPM/BP were excellent in 12 cases, good in 7, poor in 1 and unknown in 1 case. The overall efficacy rate was 95.0%. 3. Concentration of PAPM in cerebrospinal fluid after 1 hour drip intravenous administration in 1 case of purulent meningitis were 6.84 micrograms/ml at the acute stage and 3.28 micrograms/ml at the recovering stage. 4. Neither side effects nor abnormal laboratory findings were observed except 1 case of increase of thrombocytosis out of 19 cases. 5. From the results, PAPM/BP was determined to be an efficacious and safe drug for the therapy of pediatric infection.

[Investigation of panipenem/betamipron levels in sera and various tissues in patients of orthopedic surgery].

Panipenem/betamipron (PAPM/BP), a new parenteral carbapenem antibiotic, was investigated with regard to their levels in sera and various tissues collected from patients under orthopedic surgery. The subjects were 17 patients, complaining low back pain and hospitalized for surgical operations. PAPM/BP was administered by intravenous drip infusion for 30 minutes of a dose of 500 mg/500 mg. Serum and cerebrospinal fluid (CSF) specimens were taken from 8 patients at 15-70 minutes after administration and assayed for PAPM and BP levels. Serum, bone, and joint capsule samples where taken from the other 9 cases at 25-127 minutes after administration and assayed. PAPM levels in CSF were considerably lower than those in serum. They were 23.74-1.11 micrograms/ml in sera, 0.31-0.05 micrograms/ml in CSF's during 15 to 70 minutes after administration. PAPM levels were 27.85-2.97 micrograms/ml in sera, 2.54-0.20 micrograms/g in bones, 5.63 and 1.67 micrograms/g in joint capsules during 25 to 127 minutes after administration. BP levels in sera and various tissues were low compared to those of PAPM. These results showed that PAPM was detected at higher levels than 0.2 microgram/g in various tissues, except CSF during 20 to 120 minutes after drip infusion of PAPM/BP 500 mg/500 mg for 30 minutes.

Gamma-aminobutyric acid-transaminase deficiency: a newly recognized inborn error of neurotransmitter metabolism.

Cerebrospinal fluid aminoacid analysis in a girl with severe psychomotor retardation, hypotonia, hyperreflexia and growth acceleration showed highly increased levels of free gamma-aminobutyric acid (4.8 mumol/l; range in twenty controls 0.04-0.12, median 0.08), homocarnosine, a dipeptide of gamma-aminobutyric acid and histidine (23.4 mumol/l; control range 4.0-8.7, median 7.6) and of beta-alanine, an alternative substrate for gamma-aminobutyric acid-transaminase (0.48 mumol/l; control range 0.02-0.06, median 0.05). Liver gamma-aminobutyric acid-transaminase activity was deficient (0.07 mumol/mg protein h; range in ten controls 0.31-0.69, median 0.38). Fasting plasma growth hormone levels were increased (7.9-38.4 ng/ml; nl less than 5). Brain evoked responses were suggestive of leukodystrophy. A brother of this patient, showing a similar clinical picture, had died at one year. Postmortem examination of his brain showed leukodystrophy of the type seen in amino acidopathies such as phenylketonuria. This appears to be the first report of gamma-aminobutyric acid-transaminase deficiency.