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An isotope ratio mass spectrometer and an ion trap mass spectrometer were coupled in parallel to one gas chromatograph. This system provides the means to obtain information about both chemical nature and isotopic composition of a given compound under identical gas chromatographic conditions.

*Department of Pediatric Neurology, University Children’s Hospital, Heidelberg; †Society of Epilepsy Research, Bielefeld; and‡University Children’s Hospital, Mannheim, GermanySummary: Purpose: To estimate the incidence rate of epilep-sies and epileptic syndromes in German children and adoles-cents aged 1 month to

Hyponatraemia in patients with an acute central nervous system disease can be caused by two different mechanisms: (1) retention [corrected] of free water, i.e. the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and (2) excessive sodium retention [corrected], i.e., the cerebral salt wasting syndrome (CSW). Although the concept of CSW is well known in adult medicine, it is still not established in child neurology. We conducted a retrospective analysis of electrolyte disturbances in 195 children with various acute CNS diseases. In 20 children (10.3%) hyponatraemia with plasma sodium below 130 mmol/l was identified. On the basis of clinical and laboratory data 7 of these 20 children were diagnosed as having SIADH, and the other 9 children, as having CSW. Our data suggest that hyponatraemia attributable to CSW is at least as frequent in children as SIADH. Because of their different pathophysiological mechanisms, which require diametrically opposed therapeutic regimens, early differential diagnosis is mandatory if the correct treatment is to be given.

Short Report 691One carrier parent for homocystinuria was a carrier of the factor V mutation and ofthe common MTHFR variant; this father had unexplained paraparesis at 65 years.Overall, our study supports the association between MTHFR and factor V muta-tions in genetic predisposition to thrombosis, although one of our patients may stillbe too young to manifest this complication. However, at least one other patient inour study had strokes or thrombosis in the absence of this factor V mutation. Insearching for causes of thrombosis, it is evident that multiple genetic risk factorsneed to be considered.

The assessment of energy expenditure is valuable for the management of children with various conditions such as obesity and failure to thrive. Total daily energy expenditure (TDEE) includes resting energy expenditure (REE), energy expenditure during physical activity, dietary thermogenesis and growth. TDEE can be assessed by using the double-labelled water technique, but it has complex pitfalls and potential sources of errors and is impractical for everyday use. As REE is a substantial part of TDEE (65%-70%) and computerised indirect calorimeters have become recently available, this non-invasive, relatively cheap and easy to use technique is valuable for the assessment of short-term changes in energy metabolism. This can be used to assess REE of children with inborn errors of metabolism, whilst well and during episodes of metabolic decompensation and therefore to accurately determine energy intake.

Quantitative reference values for the concentrations of organic acids in cerebrospinal fluid (CSF) and plasma, as well as ratios of individual organic acids between CSF and plasma, were determined in twenty-three pairs of samples from pediatric patients. Twenty-six organic acids were present and quantifiable in all or the majority of plasma and CSF specimens (limit of detection 1 mumol/l). There were substantial differences between subgroups of organic acids, best reflected by the ratios of individual acids between CSF and plasma. Metabolites related to fatty acid oxidation were present in CSF in substantially lower amounts than in plasma. Organic acids related to carbohydrate and energy metabolism and to amino acid degradation were present in CSF in equal or slightly lower amounts than in plasma. Finally, some organic acids were found in substantially higher amounts in CSF than in plasma, e.g. glycolate, glycerate, 2,4-dihydroxybutyrate, citrate and isocitrate. Quantitation of organic acids in CSF and plasma should aid diagnosis and monitoring of treatment of patients with organic acid disorders.

Concentrations of organic acids in cerebrospinal fluid (CSF) appear to be directly dependent upon their rate of production in the brain. There is evidence that the net release of short-chain monocarboxylic acids from the brain is a major route for removing these products of cerebral metabolism. Concentrations of organic acids in blood and CSF are largely independent of each other. Quantitative reference values for the concentrations of organic acids in CSF and plasma as well as ratios of individual organic acids between CSF and plasma were determined in 35 pairs of samples from paediatric patients. Over 25 organic acids were quantifiable in all or in the majority of CSF and/or plasma specimens (limit of detection 1 mumol/L). There were substantial differences in the CSF/plasma ratios between subgroups of organic acids. Metabolites related to fatty-acid oxidation were present in CSF in substantially less amounts than in plasma. Organic acids related to carbohydrate and energy metabolism and to amino acid degradation were present in CSF in the same amounts as or slightly smaller amounts than in plasma. Finally, some organic acids were found in substantially higher amounts in CSF than in plasma, e.g. glycolate, glycerate, 2,4-dihydroxybutyrate, citrate and isocitrate. Studies of organic acids in CSF and plasma samples are presented from patients with 'cerebral' lactic acidosis, disorders of propionate and methylmalonate metabolism, glutaryl-CoA dehydrogenase deficiency and L-2-hydroxy-glutaric aciduria. It became apparent that derangements of organic acids in the CSF may occur independently of the systemic metabolism. Quantitative organic acid analysis in CSF will yield new information on the pathophysiology in the central nervous system (CNS) of these disorders and may prove necessary for successful monitoring of treatment of organoacidopathies, which present mainly with neurological disease. For example, in glutaryl-CoA dehydrogenase deficiency the urinary excretion of glutarate appears to be an inadequate parameter for monitoring the effect of dietary therapy, without plasma and CSF determinations. In L-2-hydroxyglutaric aciduria the elevation of L-2-hydroxyglutarate was found to be greater in CSF than in plasma. In addition, some other organic acids, glycolate, glycerate, 2,4-dihydroxybutyrate, citrate and isocitrate, were also elevated in the CSF of the patients out of proportion to normal levels in plasma and urine. High concentrations of an unknown compound, which was tentatively identified as 2,4-dihydroxyglutarate, were found in the CSF of patients with L-2-hydroxyglutaric aciduria.(ABSTRACT TRUNCATED AT 400 WORDS)

Neben der Behandlung von Vitamin-B6-abhangigen (Neugeborenen) Anfallen sowie von Anfallen bei B6-Mangel wurde Vitamin B6 bei verschiedenen Epilepsieformen eingesetzt (Hansson u. Hagberg 1968; Ekelund et al. 1969), wobei auch Kinder mit BNS-Anfallen zu finden waren (French et al. 1965). Ohtsuka et al. berichteten 1982 erstmals uber systematisch mit Vitamin B6 (tagliche Dosis 30–400 mg Pyridoxalphosphat) behandelte Kinder mit BNS-Leiden und 1987 ausfuhrlich uber Erfolge sowohl bei Kindern mit symptomatischem als auch idiopathischem BNS-Leiden: 15 (12,7%) von 118 Fallen mit West-Syndrom waren unter hochdosierter Pyridoxal-Phosphat-Behandlung anfallsfrei geworden. 12 der Kinder blieben anfallsfrei, 2 Kinder entwickelten ein Lennox-Gastaut-Syndrom, 1 Kind starb spater. 1986 publizierten Blennow u. Starck 3 Falle von Kindern mit BNS-Anfallen, die erfolgreich mit einer Vitamin-B6-Dosis von 200–400 mg/kgKG/Tag behandelt worden waren.

G. F. HOFFMANN 1, F. K. T~:Evz 1, P. G. BARTH 2, H.-J. BOHLES 3, W. LEHNERT 4, E. CHRISTENSEN 5, J. VALK 6, D. RATING 1 and H. J. BREM~rt 1 Departments of Paediatrics, 1 University of Heidelberg, Im Neuenheimer Feld 150, D-6900 Heidelberg, Federal Republic of Germany; 2University of Amsterdam, The Netherlands; 3 University of Frankfurt, FRG; 4University of Freiburg, FRG; SDepartment of Clinical Genetics, University of Copenhagen, Denmark; 6Department of Radiology, Free University of Amsterdam, The Netherlands

Neben dem klassischen peroxisomalen Krankheitsbild des zerebro-hepatorenalen Syndroms (Zellwegersche Erkrankung) sind inzwischen eine Reihe weiterer Erkrankungen als primar peroxisomale Storungen erkannt worden. Es erscheint — gerade aus klinischer Sicht — sinnvoll, an der folgenden Gruppierung festzuhalten: Erkrankungen mit a) Fehlen bzw. Inaktivitat eines peroxisomalen Enzyms b) multiplen peroxisomalen Enzymdefekten c) Fehlen funktionsfahiger Peroxisomen; die Peroxisomen liegen als leere Hulle („ghost“) vor, und es resultiert ein Verlust aller peroxisomalen Enzymfunktionen.

Antiepileptic drugs taken by pregnant epileptic women are known human teratogens. They may also cause pharmacological side effects in the newborn, i.e. sedation and or withdrawal symptoms. We examined the relationship between the maternal antiepileptic therapy, neonatal behaviour and later neurological functions in infancy. The study comprised 40 children exposed in utero to a single antiepileptic drug (phenobarbitone, phenytoin, valproic acid). Valproic-acid-exposed children were the highest compromised, except for apathy, which was most profound in phenobarbitone-exposed neonates. Valproic acid serum concentrations at birth correlated with the degree of neonatal hyper-excitability and neurological dysfunction when children were re-examined 6 years later. We suggest that valproic acid may not only cause malformations but also cerebral dysfunction immediate and long term.

The need of quality control in neonatology demands follow-up of an increasing number of infants. These studies often have a considerable dropout rate, are time-consuming and expensive. In 1992 we conducted a follow-up study by telephone interviews with all parents of very premature (< 32 weeks) infants, born 1986-1990 at the Perinatal Center of Heidelberg (n=442). Letters were written to all families before calling. 44% of the families had moved and had to be traced. Nevertheless 96% could be reached. The average time (±SD) needed per child was 65 (± 40) minutes (28 minutes for organization and 37 minutes for the standardized interview). The average costs per child were DM 12. It was our impression, that telephone interviews even can be superior to clinical interviews in some respects (emotional safety, no reponse-effects, not influenced by child's temporary mood). A validation of the method was performed with a subgroup of 52 children at the age of 12 to 24 months. At telephone, a modified version of the Griffith Scales was used. In addition, parents measured weight, length and head circumference. Afterwards, the children were examined at the hospital. High correlations (r = 0.89 - 0.97) were found for growth parameters and different subscales of the Griffith-test (motor, social, hearing/speech, coordination). Telephone interview as a new method is effective and reliable for follow-up studies of premature infants and allows nearly complete assessment of large groups of children.

In an animal model of hyperphenylalaninemia PHE was measurable by MRS in the brain in vivo. Blood and brain concentrations were not correlated (Avison et al 1990, Pediatr Res). We measured brain PHE in 4 early treated adult PKU patients (type I) during an oral load with l-PHE using localized MRS (1.5 T, standard head or surface coil, double echo localisation sequence, TE 20 ms). The PHE peak was identified at 7.4 ppm. in all patients calculating difference spectra (baseline spectra of 8 healthy subjects). PHE quantification was accomplished using the unsuppressed water signal as internal standard (Kreis et al 1993, J Magn Reson B). Blood PHE steaply increased from 981 (696 -1158) uMol/l preload to maximum within 2 h after load. After 5 h (1713 (1423-1913) uMol/l) PHE was stable, after 20 h (1581 (1440 - 1653) uMol/l PHE levels slowly decreased. Increase of brain PHE (preload 230 (80 - 340 uMol/l) was much slower and less steap and continued from 5 h (290 (260 - 330) uMol/l) to 20 h (340 (240 - 490 uMol) postload. Individual blood/brain ratios varied from 2.73 - 5.43. Using MRS to measure PHE in the brain (and thus in the affected compartment) and its dynamics of influx through the blood-brain barrier it should become possible to determine the interindividually different risk in developing brain damage on a more valid basis.(Grant DFG PH96/3-1).

The 13C-triolein breath test is a method giving evidence of extent and rate of fatty acid oxidation in newborn infants on parenteral nutrition. The test has the special advantage of being non-invasive. Triolein labeled with the stable carbon isotope 13C and emulsified in soybean-oil is used as a tracer. 10 mg of 13C triolein per kg body weight are administered intravenously. The 13CO2 resulting from the fatty acid oxidation is analysed in expired breath by ratio-mass-spectrometry. The calculated 13C elimination is reprsentative of the rate of fatty acid oxidation during the examination period. First studies on 15 premature infants have shown that an average of 27.0 ± 1.8% of the dose administered is oxidized within 4 h. The present results suggest that the oxidation rate may be related to the maturity of the prematurely born infants.

The 13C-aminopyrine (AP) breath test was used to measure the normal development of N-demethylase activity in 25 children, aged 2 days to 14 years, with normal liver function. Five mg of 13C-AP per kg body weight were administered orally. After AP-demethylation by the hepatic mixed function oxidase system 13CO2 excess was analysed in expired breath by mass spectrometry. In the first days of life no 13C excretion could be detected in unstimulated newborns. N-demethylase activity then slowly increased and reached adult levels by two years of life. Though the range of normal values showed considerable scattering, patients with liver disease or with enzyme induction following anticonvulsant therapy could be well discriminated. This study of the 13C-aminopyrine breath test in children provides evidence for the assumption that hepatocellular function and development of specific enzymatic activities can be measured by such non-invasive methods. It may be expected that breath tests making use of a broader spectrum of 13C-labeled substrates will prove applicable to study prenatal inducibility and other aspects of developing hepatocellular and intestinal function of children in health and disease.

Gamma-hydroxybutyric aciduria is a disorder of gamma-aminobutyric acid metabolism in which a compound of known neuropharmacologic activity accumulates. We have studied two patients in whom high levels of gamma-hydroxybutyric acid were found in blood, urine and cerebrospinal fluid. A coupled assay has been developed which estimates succinic semialdehyde dehydrogenase activity in isolated human lymphocytes. The mean activity of succinic semialdehyde dehydrogenase in a control and the four parents and two healthy siblings of these patients was 8.8 +/- 1.9 pmol . min-1 . mg-1 protein. In the patients the activities were 0.8 and 1.1 pmol . min-1 . mg-1 protein, approximately 9-13% of control. In the presence of saturating amounts of NAD+, lymphocyte sonicates, derived from the patients accumulated a significant amount of 14C-succinic semialdehyde from 14C-gamma aminobutyric acid, whereas none could be detected in controls. The data suggest a deficiency of succinic semialdehyde dehydrogenase in these patients, the first documented defect of the metabolism of gamma-aminobutyric acid in man.

In a series of experiments in rats it was possible to prove that δ8-THC has the same type of effectiveness as the stereo-isomeric δ9-THC.

Purpose: At present, neonatal seizures are usually treated with Phenobarbital (PB) despite the limited efficacy and the potential risk this treatment holds for the developing brain. We report here a prospective pilot feasibility study on the use of Levetiracetam as monotherapy in the treatment of neonatal seizures. Methods: Six newborns (body weight > 2000 g, gestational age > 30 weeks) presenting with neonatal seizures were enrolled. Patients whose seizures were caused by electrolyte disturbances or hypoglycemia, or whose seizures did respond to pyridoxine were excluded. Patients previously treated with other antiepileptic drugs (AEDs), with the exception of single PB doses before and during titration, were excluded. LEV was administered orally, increasing the dose by 10 mg/(kg day) over 3 days. Endpoint was the need of any additional AEDs (or PB) after day 3, or 3 months of LEV treatment. A decision regarding further treatment was made on an individual basis and follow-up was documented up to 8 months of age. Results: No severe adverse effects were observed. Mild sedation was reported in one infant. All six patients treated with oral LEV became seizure free within 6 days. Five patients remained seizure free after 3 months with ongoing LEV monotherapy. One infant developed pharmacoresistent epilepsy. Seizures relapsed later in the clinical course of two more patients, one of whom was no longer under LEV therapy. Discussion: Results from our small patient group indicate that LEV may be an alternative therapeutic option in neonatal seizures.

The urinary excretion of 4- or γ-hydroxybutyric acid (GHB) was first reported by Jakobs et al. (1981) in a child with neurological abnormalities (B.S., male, born 1977 of related Turkish parents). In an addendum to their paper this West Berlin group reported the discovery of siblings (F.R., female, born 1970, and M.R., male, born 1972, from non-related Lebanese parents) with metabolic profiles identical to that of their first case. Another patient with γ-hydroxybutyric aciduria (B.R., male, born 1975 of related Algerian parents) was recently described by Divry et al. (1983) from Lyon. The purpose of this communication is to review the biochemical findings in these four patients.

Atactic syndromes in childhood are difficult to classify and only few conditions are well defined and characterized by specific biochemical abnormalities e.g. IgA deficiency in Louis Bar syndrome (McKusick 20890), elevated serum levels of phytanic acid in Refsum’s disease (McKusick 26650) or a s-lipoproteinaemia in Bassen-Kornzweig syndrome (McKusick 20010). In 1981 we observed a Turkish boy who suffered from a non-progressive ataxia with muscular hypotonia. He excreted large amounts of 4-hydroxybutyric acid (GHB) in his urine. The biochemical findings in this boy led us to postulate a deficiency of succinic semialdehyde (SSA) dehydrogenase, as the first recognized inborn error of GABA metabolism (Jakobs et al., 1981).

A method has been developed for the simultaneous quantitative determination of valproic acid (2-propylpentanoic acid) and its metabolites 2-propyl-2-pentenoic acid (trans), 2-propyl-3-pentenoic acid (trans), 2-propyl-4-pentenoic acid, 3-hydroxy-2-propylpentanoic acid, 4-hydroxy-2-propylpentanoic acid, 5-hydroxy-2-propylpentanoic acid, 3-oxo-2-propyl-pentanoic acid, and and 2-propylglutaric acid. All compounds were extracted at pH 5.0 with ethyl acetate. The concentrated extracts were trimethylsilylated and the resulting mixtures analyzed by a gas chromatography-mass spectrometry-computer system operated in the selected ion monitoring mode. Linear calibration curves were obtained in the concentration ranges studied (0.1-20 microgram/ml for metabolites, 0.1-150 microgram/ml for valproic acid. The recoveries of the drugs were between 92 and 97%. The relative standard deviations were between 3.9 and 8.1% (analysis of multiple 10-microliter samples of patient urine). The lower detection limits were found to be between 2.8 and 18 ng/ml using 200-microliter serum samples. The derivatized extracts were stable for at least one week. Applications of the method described include studies of placental transfer for valproic acid and metabolites in the human, the elimination of these substances by the neonate, their transfer via mother's milk, and their levels in mouse brain.

In 23 children with febrile convulsions the concentration of gamma-aminobutyric acid (GABA) in lumbar cerebrospinal fluid (CSF) was measured by a radioreceptor assay. The mean CSF GABA concentration of 134 (range, 73-294) pmoles/ml was significantly lower than that of 16 seizure-free children serving as controls, who had 210 (range, 117-475) pmoles/ml. The reduction in CSF GABA levels in patients with febrile convulsions was not reflected in plasma GABA concentrations. These data provide further evidence that impairment of GABA neurotransmission may contribute to an increased seizure propensity.

A coupled assay using [14C]4-aminobutyric acid and a direct assay using [14C]succinic semialdehyde have been designed to assay te activity of succinic semialdehyde dehydrogenase in a patient with 4-hydroxybutyric aciduria and family members. In the coupled assay less than 3% of control succinic semialdehyde dehydrogenase activity was found in lysates of lymphocytes isolated from whole blood of the patient. In the direct assay there was no detectable activity of the enzyme in lysates of isolated lymphocytes or cultured lymphoblasts. Results indicated the parents to be heterozygous carriers carriers of the abnormal gene, consistent with an autosomal recessive inheritance.

The association of fetal and neonatal distress, birth measurements, major malformations, and minor anomalies was studied prospectively in 14 infants of women with epilepsy who were receiving valproic acid (VPA) monotherapy and in 12 infants of women with epilepsy who were receiving VPA in combination with other anticonvulsant drugs. Comparison was made with 26 matched-pair controls and 116 controls from a larger study of antiepileptic drugs. During the first trimester, total VPA serum concentrations were well above therapeutic levels (100 to 184 micrograms/ml) in two women receiving high VPA doses (2000 and 1500 mg daily). Although dosage remained the same, serum concentrations decreased during pregnancy to therapeutic levels (33.9 to 57.0 micrograms/ml). The VPA percent free fraction increased in the third trimester and was threefold higher at birth. Almost half of the infants exposed to VPA monotherapy were distressed during labor, and 28% had low Apgar scores. Fetal and neonatal distress may be caused by the high VPA percent free fraction during labor and at birth. Mean body measurements at birth after VPA monotherapy were comparable to those in the matched control group, but were reduced in the group of infants receiving VPA combination therapy. Four infants exposed to VPA monotherapy were born with major malformations. The median number of minor anomalies was four times higher in infants whose mothers received VPA alone or VPA combination therapy than in controls. Seven infants had a pattern of craniofacial and digital anomalies that was distinctly different from that observed after in utero exposure to other anticonvulsant medications. The occurrence of major malformations and the number of minor anomalies may be dose related.

Fourteen epileptic women treated with primidone, either alone or in combination with other antiepileptic drugs, were studied prospectively during their pregnancy. Plasma levels of primidone and its metabolites were monitored and correlated to findings in the offspring. Maternal serum concentrations of primidone and metabolites were generally low during pregnancy. The levels of its main metabolites--phenobarbital and PEMA--were found to drop within the first month of pregnancy in two cases. The plasma concentrations remained low until birth and rose sharply thereafter. The phenobarbital/primidone ratio (mean 0.84) and PEMA/primidone ratio (mean 0.56) in pregnant patients were found to be lower than in non-pregnant patients, except when primidone was given in combination with phenytoin in which case the expected phenobarbital/primidone (mean 2.5) and PEMA/primidone (mean 1.5) ratios were found. A ventricular septal defect was found in one of the offspring of the fourteen mothers and five children had microcephaly. There was a high incidence of poor somatic development with dystrophy (n=3) and short stature (n=2). Head circumferences (n=8), lengths (n=4) and/or weights (n=8) were below the 10th percentile in a number of children. Four children showed marked facial dysmorphy. Our preliminary data suggest that primidone intake during pregnancy may be important in the pathogenesis of minor anomalies and in the induction of poor somatic development.

By scoring EEG patterns (hypsarrhythmia = 10, absence of sleeping patterns = 10, focal epileptic discharge = 5, general-treatment or in whom infantile spasms never disappeared even during ACTH. A low voltage EEG did not have any ending ACTH therapy free of seizures showed lower scores compared to those infants relapsing after the end of ACTH treatment or in whom infantile spasms never disappeared even during ACTH. A low voltage EED did not have any prognostic significance. Using EEG scores it might be possible to separate non-responders and responders after 3 weeks of ACTH therapy, thus shortening ACTH treatment in non-responding infants.

Cerebrospinal fluid in 69 children with cerebral palsy (CP) of different etiology was examined by an improved method of agarose-gel electrophoresis. The protein pattern was normal in 12 cases only. In children with CP caused by congenital and postnatal infections raised psi-globulin fractions and the appearance of oligoclonal phi-globulin bands were the most obvious finding. In patients with CP due to malformations or perinatal brain damage and in children with CP of unknown etiology decreased prealbumin and increased albumin values were combined with hydrocephalus e vacuo in about half of the cases. Less frequent changes of the beta-globulin fractions were found, an increase of the beta-fraction being more rare than a decrease of the tau-globulin.

In 14 children with epilepsy, 51 with febrile convulsions and 22 with meningitis gamma-aminobutyric acid (GABA) concentrations in lumbar CSF were determined. While the mean for CSF GABA concentrations for all epileptic children was unchanged [144 (range: 73-285) pmol/ml; controls: 148 (range: 90-243) pmol/ml] extraordinarily high GABA levels were found in the CSF of two children on valproate (525 and 557 pmol/ml) and remarkably low GABA concentrations in hitherto untreated epileptic children [109 (range: 67-176) pmol/ml]. Children with febrile convulsions [103 (range: 63-170) pmol/ml] and acute meningitis [105 (range: 65-171) pmol/ml] had significantly decreased CSF GABA concentrations (P less than 0.001 and P less than 0.02 compared with controls). The data indicate that valproate intake increases dramatically the GABA concentrations in the CSF of epileptic children. Furthermore, the study supports the concept that low GABAergic activity within the CNS may be one cause for an increased seizure frequency.

Objective. Mevalonic aciduria is a consequence of the deficiency of mevalonate kinase, the first enzyme after 3-hydroxy-3-methylglutaryl-coenzyme A reductase in the biosynthesis of cholesterol and nonsterol isoprenes. To establish the clinical and biochemical phenotype of mevalonic aciduria, the authors assembled their experience with 11 patients including attempts at therapeutic interventions. Methods. Mevalonic acid in body fluids was determined by stable isotope dilution gas chromatography/mass spectroscopy with selected ion monitoring, ubiquinone-10 concentrations by reversed-phase high-pressure liquid chromatography. Results. Varying degrees of severity of clinical illness were observed despite uniform, virtual absence of residual activity of the enzyme. The most severely affected patients have had profound developmental delay, dysmorphic features, cataracts, hepatosplenomegaly, lymphadenopathy, and anemia, as well as diarrhea and malabsorption, and have died in infancy. Less severely affected patients have had psychomotor retardation, hypotonia, myopathy, and ataxia. All patients have had recurrent crises in which there was fever, lymphadenopathy, increase in size of liver and spleen, arthralgia, edema, and a morbilliform rash. Neuroimaging studies revealed selective and progressive atrophy of the cerebellum. Mevalonic acid concentrations were found to be grossly elevated in body fluids of all patients. Concentrations of plasma cholesterol were normal or only slightly reduced. Concentrations of ubiquinone-10 in plasma were found to be decreased in most patients. Abnormalities such as hypoglycemia, metabolic acidosis, or lactic acidemia, the usual concomitants of disorders of organic acid metabolism, were conspicuously absent. Conclusions. These observations establish the broad range of clinical symptoms and biochemical findings in mevalonic aciduria. It is concluded that although patients with mevalonic aciduria have a recognizable phenotype of serious clinical manifestations, some patients are likely to remain undiagnosed and may be found in a variety of subspeciality clinics, including neurology, troenterology, cardiology, and genetics.

4-Hydroxybutyric aciduria is an inborn error in the metabolism of 4-aminobutyrate (GABA) that is of particular interest because of the accumulation of a neuropharmacologically active compound (Jakobs et al., 1981; Divry et al., 1983). We have localized the defect in this condition to succinic semialdehyde dehydrogenase activity (SSDH, succinic semialdehyde: NAD+ oxidoreductase, EC 1.2.1.24) using an indirect coupled assay in which the precursor was U-14C-GABA. Heterozygosity could not be demonstrated with that assay. We have now developed a sensitive direct assay for SSDH using enzymatically prepared U-14C-succinic semialdehyde. Lysates of lymphocytes have been employed and the enzymatic product, 14C-succinic acid, has been quantified by liquid partition chromatography (LPC). It is the purpose of this report to present the activities of SSDH in lysates of lymphocytes isolated from whole blood of two patients with this disorder, their parents and siblings. The data establish the molecular defect as a deficiency of succinic semialdehyde dehydrogenase and are consistent with an autosomal recessive mode of inheritance.

1136 URINARY EXCRETION OF GAMMA-HYDROXYBUTYRIC ACID IN A PATIENT WITH NEUROLOGICAL ABNORMALITIES; A NEW INBORN ERROR OF AMINO ACID METABOLISM?

Measurement of fatty acid oxydation in low-birth-weight infants with the 13 C-triolein breath test

Measurement of specifically labelled CO2 in exspired breath after aminopyrine (AP) demethylation by the hepatic mixed function oxidase system has been shown to be a reliable method for estimation of hepatocellular function. We used the 13C-AP breath test to measure the normal development of the N-demethylase activity and started 13C-methacetin breath test for investigation of O-dealkylation in children. 25 children with normal liver function, aged 2 days to 14 years, received 5 mg/kg body weight AP orally. 13CO2 analysis in breath was performed with a mass spectrometer Varian MAT 230. Results were calculated as cumulative %-recovery of the administered dose. 13C after 2 hours (%-dose), corrected for body weight and endogenous CO2 production. In neonates no 13C excretion could be detected. N-demethylase activity then slowly increased and reached adult levels by 2 years of life.(%-dose = 12.2 ± 2.1). Children with liver disease (%-dose = 4.0 ± 1.3) and treated with antiepileptic drugs (%-dose=16.7 ± 2.5) could be well discriminated. Neonates whose epileptic mother were treated with primidone during pregnancy showed a 13C excretion similar or better than normal adults, thus demonstrating pre- or perinatal inducibility of the N-demethylase activity.

Enzyme activity for demethylation processes can be estimated in vivo non-invasively by 13C-breath tests (BT). After oral intake of stable isotope labeled 13C-aminopyrine (AP) (2 mg/kg) resp. 13C-methacetin (MAC) (1,5 mg/kg) 13CO2-concentration in breath samples measured by ratio mass-spectrometry will reflect cytochrom P450 dependent AP-N-demethylation resp. P448 MAC-O-demethylation. Neonates of epileptic women exposed prenatally to anticonvulsants were studied by 13C-AP-(n=25) and 13C-MAC-BT (n=18) while 6 non-exposed newborns served as controls. Half life times of diaplacentally acquired anticonvulsants were determined in 14 resp. 7 of the exposed neonates. The 2h cumulative 13C-elimination of exposed newborns (7.1 range: 3.4-15.0 (%13C-dose) ) was significantly (p