Role of cardiolipin on tBid and tBid/Bax synergistic effects on yeast mitochondria

The apoptotic effector Bid regulates cell death at the level of mitochondria. Under its native state, Bid is a soluble cytosolic protein that undergoes proteolysis and yields a 15 kDa-activated form tBid (truncated Bid). tBid translocates to mitochondria and participates in cytochrome c efflux by a still unclear mechanism, some of them at least mediated by Bax. Using mitochondria isolated from wild-type and cardiolipin (CL)-synthase-less yeast strains, we observed that tBid perturbs mitochondrial bioenergetics by inhibiting state-3 respiration and ATP synthesis and that this effect was strictly dependent on the presence of CL. In a second set of experiments, heterologous coexpression of tBid and Bax in wild-type and CL-less yeast strains showed that (i) tBid binding and the subsequent alteration of mitochondrial bioenergetics increased Bax-induced cytochrome c release and (ii) the absence of CL favors Bax effects independently of the presence of t-Bid. These data support recent views suggesting a dual function of CL in mitochondria-dependent apoptosis.

Intestinal permeability in children: variation with age and reliability in the diagnosis of cow's milk allergy

OBJECTIVE

To analyse to what extent age may alter intestinal permeability (IP) in children and to assess its reliability according to clinical manifestations in cow's milk allergy (CMA).

DESIGN

A routine prospective study was performed in 200 children (12.5+/-23 mo, 0.5-168 mo) presenting with clinical manifestations suggesting CMA. Controls (n = 105) were those with a negative cow's milk challenge, whereas CMA children (n = 95) fulfilled ESPGHAN criteria. Permeability was measured as a percentage of urinary excretion of lactitol (L, %) and mannitol (M, %) (0.1 g/kg for each, oral absorption after a 6 h fast, 5 h urine collection, analysis by gas chromatography) and determination of the L/M ratio (L/M, %).

RESULTS

In control children, L/M correlated negatively with age (r -0.33, p = 0.0006), whereas in those with CMA no correlation was found. Median L/M was significantly higher in CMA children (n = 95) than in controls (n = 105), 4.35+/-7.57% (95% CI 5.30-8.39%) vs 1.97+/-0.87% (95% CI 1.76-2.09%), (p = 0.0001). With a L/M cut-off value defined as mean + 2 SD of controls, in CMA IP exhibited a 68% sensitivity and a 77% negative predictive value. The highest sensitivity (70%) was seen at ages 6-12 mo and the lowest (58%) at age more than 3 y. An abnormal IP was seen in 80% of CMA children with digestive manifestations, in 43% with extra-digestive, 68% with mixed and 40% with anaphylactic manifestations.

CONCLUSION

IP correlates negatively with age in control children and is altered in children with CMA. The test is at its most accurate in the diagnosis of CMA when done at ages 6-12 mo, when there are digestive manifestations.

Simvastatin does not normalize very long chain fatty acids in adrenoleukodystrophy mice

X-linked adrenoleukodystrophy (ALD) is a genetic demyelinating disorder characterized by accumulation of very long chain fatty acid (VLCFA) in tissues. Lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, normalizes VLCFA in fibroblasts and plasma from ALD patients. We dietary treated ALD mice with simvastatin, an analog of lovastatin with similar pharmacokinetics and effects on plasma VLCFA in ALD patients at 20 or 60 mg/kg/day for 6-12 weeks. No decrease of VLCFA content was observed in mouse tissues, including the brain. A significant increase of VLCFA was rather observed in the brain of ALD mice at 60 mg/kg/day.

Etiological diagnosis of primary adrenal insufficiency using an original flowchart of immune and biochemical markers

Approximately 70-80% of cases of primary adrenal insufficiency are classified as idiopathic. An effective protocol for the etiological diagnosis of primary adrenal insufficiency is needed to ensure correct patient management. With the aim of developing an algorithm for the etiological diagnosis of primary adrenal insufficiency, we studied 56 Italian patients with nonsurgical primary adrenal insufficiency and 24 French patients with X-linked adrenoleukodystrophy (ALD) for serum levels of adrenal cortex, steroid-21-hydroxylase (21OHAb), islet cell (ICA), glutamate decarboxylase (GAD65Ab), IA2/ICA512 (ICA512Ab), thyroid peroxidase (TPOAb) autoantibodies, and plasmatic concentrations of very long chain fatty acids (VLCFA). High levels of 21OH and adrenal cortex antibodies were found in 35/42 (83%) and 17/42 (40%) Italian patients with idiopathic adrenal insufficiency, respectively. Levels of adrenal autoantibodies correlated inversely with disease duration (P < 0.0001). Elevated VLCFA were found in 4/42 (10%) idiopathic patients. A total of 34/35 (97%) idiopathic patients with a disease duration of less than 20 yr was positive for either 21OHSAb or elevated levels of VLCFA. None of 14 patients with posttuberculosis adrenal insufficiency had elevated levels of either adrenal antibodies or VLCFA. ICA, GAD65Ab, ICA512Ab, and TPOAb were found in 6/56 (11%), 8/56 (14%), 4/56 (7%), and 23/56 (41%) patients, respectively. None of 24 French ALD patients with adrenal insufficiency was positive for organ-specific autoantibodies. The measuring of 21OH antibodies and plasma VLCFA levels enabled a correct diagnosis of autoimmune (89%) and ALD (8%) in 97% of patients with idiopathic primary adrenal insufficiency of less than 20 yr of duration. The results of our study have important therapeutic and prognostic implications.

The optimized use of gas chromatography-mass spectrometry and high performance liquid chromatography to analyse the serum bile acids of patients with metabolic cholestasis and peroxisomal disorders

We have measured the bile acids in human serum as methyl ester-trimethylsilyl ethers by gas chromatography-mass spectrometry (GC-MS) using an electron ionization procedure. The overall method was validated and the detection limit (0.4 mumol/l), linearity (2-30 mumol/l), intra-day and inter-day precision, accuracy and recovery (96.2% for nor-23-deoxycholic acid as internal standard) were measured. Serum C24-bile acids profiles from 43 cholestatic patients were measured by GC-MS and by HPLC. The results obtained with the two methods were well correlated and the criteria for selecting either HPLC or GC-MS identified. The serum C24- and C27-bile acids and C29 dicarboxylic bile acid profiles for patients with generalized peroxisomal deficiencies, like Zellweger syndrome (n = 5), neonatal adrenoleukodystrophy (n = 1), infantile Refsum disease (n = 2) and from a single peroxisomal deficiency (n = 1) were also measured by GC-MS.

Multiple food allergy: a possible diagnosis in breastfed infants

Six infants suspected of food allergy during breastfeeding were evaluated using prick tests, total IgE, RASTs and intestinal permeability measurements during fast and provocation with mother's milk. An elimination diet was undertaken in mothers, removing first cow's milk protein (CMP), then, when inefficient, all foods suspected on the clinical history or a positive prick test in the child, followed by oral challenges in mother's diet with the corresponding food. The sole CMP-free diet in mothers always proved insufficient. In four, an additional diet excluding two to three other foods cleared the symptoms. Oral provocations in mother's diet with those foods were positive in all. In two, mothers turned down a diet excluding more than four foods, symptoms cleared while feeding the child with an extensively hydrolysed formula, whereas challenges with mother's milk induced immediate reactions. Intestinal permeability was altered during provocation tests with mother's milk sampled before maternal diet. Food allergy during breastfeeding may be due to multiple foods and the inefficacy of the sole CMP elimination in mothers does not rule out food sensitization.

Thermotoga hypogea sp. nov., a xylanolytic, thermophilic bacterium from an oil-producing well

A new thermophilic, xylanolytic, strictly anaerobic, rod-shaped bacterium, strain SEBR 7054T, was isolated from an African oil-producing well. Based on the presence of an outer sheath (toga) and 16S rRNA sequence analysis data, this organism was identified as a member of the genus Thermotoga. Strain SEBR 7054T possessed lateral flagella, had a G + C content of 50 mol%, produced traces of ethanol from glucose but no lactate, and grew optimally in the presence of 0 to 0.2% NaCl at 70 degrees C. Its phenotypic and phylogenetic characteristics clearly differed from those reported for the five previously validly described Thermotoga species. Therefore, we propose that strain SEBR 7054T is a member of a new species of the genus Thermotoga, Thermotoga hypogea sp. nov. The type strain of T. hypogea is SEBR 7054 (= DSM 11164).

[Exercise intolerance caused by muscular phosphorylase kinase deficiency. Contribution of in vivo metabolic studies]

A 33 year old man has been presenting since childhood an exertional muscle pain syndrome without myoglobinuria. Muscle biopsy revealed a vacuolar myopathy with glycogen excess in subsarcolemmal and intermyofibrillar spaces which was confirmed by electron microscopy. Plasma production of ammonia was abnormally high during exercise on a bicycle ergometer while the raise of lactate was normal. NMR spectroscopy showed an increased muscle glycogen content, with a slight and delayed drop of the pH during exercise. Phosphorylase b kinase activity was undetectable in muscle specimen whereas activities of others enzymes of carbohydrate metabolism were normal. Clinical presentation of our patient is compared to that of the reported cases of phosphorylase b kinase deficiency.

Requirement of glucose metabolism for regulation of glucose transporter type 2 (GLUT2) gene expression in liver

Previous studies have shown that glucose increases the glucose transporter (GLUT2) mRNA expression in the liver in vivo and in vitro. Here we report an analysis of the effects of glucose metabolism on GLUT2 gene expression. GLUT2 mRNA accumulation by glucose was not due to stabilization of its transcript but rather was a direct effect on gene transcription. A proximal fragment of the 5' regulatory region of the mouse GLUT2 gene linked to a reporter gene was transiently transfected into liver GLUT2-expressing cells. Glucose stimulated reporter gene expression in these cells, suggesting that glucose-responsive elements were included within the proximal region of the promoter. A dose-dependent effect of glucose on GLUT2 expression was observed over 10 mM glucose irrespective of the hexokinase isozyme (glucokinase K(m) 16 mM; hexokinase I K(m) 0.01 mM) present in the cell type used. This suggests that the correlation between extracellular glucose and GLUT2 mRNA concentrations is simply a reflection of an activation of glucose metabolism. The mediators and the mechanism responsible for this response remain to be determined. In conclusion, glucose metabolism is required for the proper induction of the GLUT2 gene in the liver and this effect is transcriptionally regulated.

Stable isotope determination of plasma lactate conversion into glucose in fasting infants

To quantify lactate gluconeogenesis, we developed a gas chromatography-mass spectrometry method based on the infusion of [6,6-2H2]glucose and [3-13C]lactate tracers to 12 infants aged 1-25 mo fasting for 11.5 +/- 1.5 h. Both rates of appearance of plasma glucose (26.7 +/- 2.6 mumol.kg-1.min-1, 4.8 +/- 0.5 mg.kg-1.min-1) and lactate (30.8 +/- 3.1 mumol.kg-1.min-1, 2.8 +/- 0.3 mg.kg-1.min-1) were remarkably elevated compared with adult values. The interconversion of plasma lactate and glucose was determined by 1) measuring the incorporation of 13C from [3-13C]lactate into plasma glucose; 2) correcting for the metabolic exchange of carbon atoms in the tricarboxylic acid cycle. For this purpose, an additional group of six infants was infused with [3-13C]lactate, and the distribution of 13C at specific carbon positions in the glucose molecule was determined using relevant ions in the electron-impact mass spectrum of its 1,2,5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative; and 3) measuring the reverse conversion of glucose to lactate in five other infants infused with [1-13C]glucose. We found that 54 +/- 2% of glucose was derived from plasma lactate (14.4 +/- 1.3 mumol.kg-1.min-1, 2.6 +/- 0.2 mg.kg-1.min-1). Lactate and glucose rates of appearance were correlated (r = 0.58, P < 0.05) and decreased with fasting duration (r = 0.66, P < 0.02). The correction factor for carbon exchange in the tricarboxylic acid cycle was 1.14 +/- 0.11.(ABSTRACT TRUNCATED AT 250 WORDS)

Retroviral-mediated gene transfer corrects very-long-chain fatty acid metabolism in adrenoleukodystrophy fibroblasts

Adrenoleukodystrophy (ALD), a lethal demyelinating disease of the brain, is caused by mutations of a gene encoding an ATP-binding transporter, called ALDP, localized in the peroxisomal membrane. It is associated with a defective oxidation of very-long-chain fatty acids, leading to their accumulation in many tissues. This study reports that the retroviral-mediated transfer of the ALD cDNA restored very-long-chain fatty acid oxidation in ALD fibroblasts in vitro following abundant expression and appropriate targeting of the vector-encoded ALDP in peroxisomes. The same method may be used in hematopoietic cells as a further step of a gene therapy approach of ALD.

Ketone body turnover at term and in premature newborns in the first 2 weeks after birth

Using the infusion of D-(-)-3-hydroxy-[1,2,3,4,-13C4]butyrate at tracer doses, we measured total ketone body turnover in 13 premature and 10 at term infants in the first 2 weeks after birth. The premature infants received parenteral and/or oral feeding. The normal newborns were either recently fed or briefly fasting. The premature and the fed at term infants had comparable concentrations of ketone body (476 +/- 86 and 406 +/- 78 mumol/l) and free fatty acids (FFA) (309 +/- 47 and 325 +/- 75 mumol/l). In the premature newborns, ketone body turnover rates (3.2 +/- 0.2 mumol kg-1 min-1) were 74% that of fed newborns at term (4.3 +/- 0.3 mumol kg-1 min-1, p < 0.05), and 18% that of normal newborns during a brief fast (17.3 +/- 1.3 mumol kg-1 min-1, p < 0.01). Ketone body production rates correlated with plasma FFA concentrations in both groups (r = 0.62 and 0.69, p < 0.05). However, for a similar plasma FFA content, ketone production was 2- to 3-fold lower in the premature, indicating an immature hepatic capacity to convert FFA into ketones. Our study therefore shows that ketogenesis is already active in infants born 10 weeks before normal term and continuously fed, but that daily ketone production is lower than at term.

Determination of 13C enrichment at specific positions of plasma glucose by gas chromatographic-mass spectrometric analysis of the 1,2:5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative

To determine 13C enrichment at specific positions of glucose, plasma samples (50-100 microliters) were deproteinized using ethyl alcohol, centrifuged, and evaporated to dryness, and the residues were derivatized with acetone/H2SO4 (100/1, v/v). After acetylation, the 1,2:5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative was analyzed by gas chromatography-mass spectrometry. The method was tested using mixtures of natural and 13C-labeled glucose molecules. Ions at m/z 113, 114, 143, 144, 287, and 288, corresponding to the C2-C4, C1-C4, and C1-C6 parts of natural or 13C-labeled glucose molecule, respectively, were selectively monitored to determine the 13C content of these fragments. This method was applied to the study of plasma glucose-labeling pattern following the infusion of [3-13C]lactic acid at tracer doses. Assuming equilibration of label through triose-phosphate isomerization in vivo, we determined the 13C enrichment of carbons 1, 2, and 3 of glucose; the values for E1/E3 and E2/E1 ratios of 8.1 and 0.77, respectively, are consistent with those obtained in studies using radioactive tracers.

[Medium-chain acyl-CoA dehydrogenase deficiency: contribution of molecular biology]

BACKGROUND

Medium-chain acyl-CoA dehydrogenase deficiency is the most frequent cause of defective congenital fatty acid oxidation. Its molecular characterization is now possible. Case n. 1. A girl, 15 month-old, was admitted because she suffered from fever and vomiting, requiring the administration of aspirin. One day later, she showed signs of drowsiness and hypotonia; her blood glucose concentration was 0.3 g/l. She was given intravenous glucose and this episode rapidly passed. Case n. 2. A boy, brother of the preceding patient, was routinely investigated; he was never symptomatic. Case n. 3. A boy, sibling of the two preceding children, was admitted at the age of 18 months because he had gone into a coma during a febrile episode. His blood glucose concentration was 0.15 g/l. This episode was rapidly resolved by a glucose infusion. His fasting blood concentrations of glucose, non esterified fatty acids. beta-hydroxybutyrate, lactate and pyruvate were normal as were his blood carnitine and ammonia, but he showed elevated urinary excretion of dicarboxylic acids.

METHODS

Genomic DNA was extracted from peripheral leukocytes of the three sibs and their parents. The A-->G mutation at nucleotide 985 of the MCAD gene was detected by amplification and creation of a restriction site (ACRS). The implicated segment of this gene was amplified by PCR.

RESULTS

ACRS showed that the symptomatic children were homozygous for the A-->G mutation, whereas their parents were heterozygous. The third asymptomatic child did not carry the mutation.

CONCLUSIONS

Molecular biology techniques are appropriate for diagnosing this potentially lethal disease and their use for screening is important for disease prevention.

A new peroxisomal disease with impaired phytanic and pipecolic acid oxidation

Phytanic acid (PA) accumulates in patients with adult Refsum disease (ARD) and with peroxisomal disorders. In three related patients with ARD, PA levels were moderately increased in plasma, whereas phytanic oxidation was severely deficient in the fibroblasts. Two of these patients had a significant increase of pipecolic acid in plasma, a finding not reported in ARD, and a fourth related patient, a brother, died at age 17 from a progressive neurologic disorder with unusual clinical and neuropathologic (a spongy degeneration of the white matter) abnormalities for ARD. The first step of L-pipecolic acid degradation occurs in peroxisome. In these patients, the accumulation of PA could have resulted from an impaired capacity to degrade pristanic acid rather than PA. The activity of pristanic oxidase, measured in fibroblasts, was normal, as were two other peroxisomal enzymes, lignoceric acid oxidase and dihydroxyacetone phosphate transferase. Since both mitochondria and peroxisomes are involved in PA alpha-oxidation, we propose that these four related patients presented various phenotypical variants of a novel peroxisomal disease with impairment of PA and pipecolic acid oxidation.

A two-year trial of oleic and erucic acids ("Lorenzo's oil") as treatment for adrenomyeloneuropathy

BACKGROUND

Adrenomyeloneuropathy is an X-linked recessive disorder characterized by myelopathy, peripheral neuropathy, and cerebral demyelination, which develop in association with the accumulation of very-long-chain fatty acids. The administration of oleic and erucic acids inhibits the synthesis of very-long-chain fatty acids. Recently such dietary treatment has been widely publicized as a possible cure for this disease.

METHODS

We conducted an open trial in 14 men with adrenomyeloneuropathy, 5 symptomatic heterozygous women, and 5 boys (mean age, 13 years) with preclinical adrenomyeloneuropathy. The patients ate a low-fat diet and received daily doses of glycerol trioleate oil (1.7 g per kilogram of body weight) and glycerol trierucate oil (0.3 g per kilogram). Clinical manifestations, cerebral and spinal cord magnetic resonance imaging (MRI) scans, nerve conduction, and brain-stem auditory and somatosensory evoked potentials were studied prospectively over 18 to 48 months. Plasma levels of very-long-chain fatty acids and the side effects of erucic acid were monitored monthly.

RESULTS

By week 10, plasma very-long-chain fatty acid levels declined nearly to normal. Nonetheless, over a mean follow-up of 33 months none of the 14 men with adrenomyeloneuropathy improved. In nine men there was functional deterioration, coincident in four with new cerebral lesions on MRI. In a single patient there was a reduction in cerebellar demyelination, but without clinical improvement. In one of the five asymptomatic boys signs of myelopathy developed. There were no changes in the symptomatic heterozygous women. There was some improvement in peroneal-nerve conduction, but no detectable clinical improvement. Conduction to the parietal cortex (T12-P37 interpeak latency) worsened in both the symptomatic men and the boys with preclinical adrenomyeloneuropathy. There was no change in other somatosensory evoked potentials or in brain-stem auditory evoked potentials. Asymptomatic thrombocytopenia (< 100,000 cells per cubic millimeter) was noted in six patients.

CONCLUSIONS

In this open trial we found no evidence of a clinically relevant benefit from dietary treatment with oleic and erucic acids ("Lorenzo's oil") in patients with adrenomyeloneuropathy.

Pseudo infantile Refsum's disease: catalase-deficient peroxisomal particles with partial deficiency of plasmalogen synthesis and oxidation of fatty acids

Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum's disease are genetic disorders characterized by the virtual absence of catalase-positive peroxisomes and a general impairment of peroxisomal functions. Recent studies in these three disorders have provided morphologic evidence of peroxisomal "ghosts" of density 1.10 g/cm3 that contain membrane proteins but lack a majority of the matrix enzyme activities. We report here the biochemical studies in a female infant with clinical features of infantile Refsum's disease whose liver and fibroblasts contained cytosolic catalase but no catalase-positive peroxisomes. Oxidation of phytanic and pipecolic acids was severely impaired, whereas oxidation of very-long-chain fatty acids and dihydroxyacetone phosphate acyltransferase activity were only partially decreased. Immunoblot analysis showed that the three peroxisomal beta-oxidation enzymes (acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase) were detectable in liver tissues. The 3-ketoacyl-CoA thiolase was of the mature form (41 kD), in contrast with other peroxisomal disorders with multiple enzyme deficiencies. The majority of these peroxisomal enzyme activities were associated with two subcellular membrane vesicle fractions lacking catalase: one had the density of normal peroxisomes (1.17 g/cm3), the other, yet undescribed, a lower density (1.137 g/cm3). This suggests that peroxisomes (density = 1.17 g/cm3) and structures with lower density (density = 1.137 g/cm3) found in this patient's cultured skin fibroblasts, although lacking catalase, contained functional peroxisomal enzymes. This distinguishes this disorder from other disorders of peroxisome biogenesis.

Human beta-mannosidosis: a 3-year-old boy with speech impairment and emotional instability

Beta-mannosidosis is a recently described inherited disorder with predominantly neurological signs and symptoms as the major manifestations of the disorder. The heterogeneous manifestations of the disease have been presented in seven previous patients. We describe a further case of European descent with an infantile onset of the disease, with the features of speech impairment as the first symptom. Beta-mannosidase activity was completely deficient in the patient and a heterozygote level was found in the parents. In addition, mannosyl-N-acetylglucosamine was identified in the patient's urine in keeping with the diagnosis of beta-mannosidosis.

Protein-metabolism kinetics and energy-substrate utilization in infants fed parenteral solutions with different glucose-fat ratios

The relative effect of glucose and lipids on whole-body protein-metabolism kinetics was assessed in seven infants undergoing parenteral feeding. Protein intake was kept constant and nonprotein energy was either provided as glucose alone or as an isoenergetic glucose-lipid mixture according to a randomized crossover trial. Protein metabolism and energy-substrate utilization were assessed by a primed, constant L-[13C]leucine infusion, combined with indirect calorimetry. There was a significant difference in the pattern of energy-substrate utilization according to regime. Protein turnover (11.3 +/- 0.7 vs 9.8 +/- 0.4 g.kg-1.d-1; P less than 0.05), protein breakdown (8.4 +/- 0.6 vs 7.1 +/- 0.4 g.kg-1.d-1; P less than 0.05), and amino acid oxidation rates (2.7 +/- 0.4 vs 1.4 +/- 0.5 g.kg-1.d-1; P less than 0.05) were higher for the glucose than the glucose-lipid treatment, whereas protein-synthesis rates did not significantly differ. These results suggest that the nature of energy substrates delivered to parenterally fed infants may affect protein metabolism.

Deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase: a cause of lethal myopathy and cardiomyopathy in early childhood

A child presented in early childhood with episodes of coma and hypoglycemia and a rapidly evolutive myopathy and cardiomyopathy leading to death at 9 mo of age. Ketosis was decreased (blood beta-hydroxybutyrate: 0.07 mmol/L) despite normal plasma levels of fatty acids (0.81 mmol/L). The patient's urine contained excessive amounts of the C6 to C10 dicarboxylic acids present in almost all defects of fatty acid mitochondrial oxidation. More specifically, gas chromatography-mass spectrometry identified an accumulation of medium- and long-chain (C8 to C14) 3-hydroxy-dicarboxylic acids, suggesting a defect of the mitochondrial enzyme that normally dehydrogenates these 3-hydroxyacyl-CoA esters. Biochemical studies in the patient's cultured fibroblasts confirmed the impairment of medium- and long-chain fatty acid oxidation, and allowed the recognition of the deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase. The activities of long-, medium-, and short-chain acyl-CoA dehydrogenases and 3-ketoacyl-CoA thiolase were normal. These results describe a disorder of fatty acid metabolism that affects the liver, skeletal muscles, and myocardium. It is important to point out that long-chain 3-hydroxyacyl-CoA deficiency shares many clinical similarities with systemic carnitine deficiency, as well as with carnitine-palmityl-CoA transferase and long-chain acyl-CoA dehydrogenase deficiencies. The differential diagnosis of this disease relies on the demonstration of long-chain urinary dicarboxylic acids with a hydroxyl group in 3-position and the study of the enzyme activity in cultured fibroblasts.

Capillary gas-liquid chromatographic/mass spectrometric measurement of plasma acetate content and (2-13C) acetate enrichment

In studies where (2-13C)acetate is employed as isotopic tracer in vivo, we have reported a selected ion monitoring gas-liquid chromatographic/mass spectrometric method which allows plasma tracer enrichment as well as plasma acetate content to be determined in the same 200-500 microliters sample through the use of methacrylic acid as the assay internal standard. For standard solutions in the range equivalent to plasma acetic acid concentrations of 10-200 microM, assay precision was +/- 4.3%. For plasma samples in the physiological range (approximately 20-300 microM acetate) assay precision averaged better than +/- 5%. The use of the method is illustrated by measuring acetate turnover in a young adult.

Oxidative metabolism of linoleic acid by human leukocytes

Upon incubation with human leukocytes, [1-14C] linoleic acid is almost exclusively transformed into 13-hydroxy-9Z, 11E-octadecadienoic acid (13-HODE) if the linoleic acid concentration is lower than 50 microM. Identification of 13-HODE was done by GLC-MS at the level of its methyl ester, trimethylsilyl ether and by comparison with authentic 13-HODE in two different HPLC systems. Analysis of the products by chiral phase HPLC shows that 13(S)-hydroxy-9Z, 11E-octadecadienoic acid is by far the major metabolite formed by human leukocytes. Comparison of reactions performed with intact or lyzed cells suggests that the formation of 13(S)-HODE by human leukocytes occurs in two steps, a dioxygenation catalyzed by a 15-lipoxygenase and a reduction of intermediate 13-HPODE by a glutathione-dependent peroxidase.

Medium-chain fatty acids increase glucose production in normal and low birth weight newborns

To study the pathogenesis of hypoglycemia in low birth weight infants, glucose production was measured in five hypotrophic and four premature newborns with glycemia of 45 +/- 6 and 59 +/- 10 mg/dl, respectively. Hepatic glucose output averaged 5.7 +/- 0.4 and 5.3 +/- 0.5 mg.kg-1.min-1 in these neonates vs. 8.2 +/- 0.5 mg.kg-1.min-1 in five normal at term newborns and was correlated with glycemia (P less than 0.02). Despite normal plasma free fatty acids, the low birth weight infants had low ketone levels of 163 +/- 72 and 126 +/- 65 vs. 263 +/- 60 microM in normals. Oral administration of medium-chain triglycerides to the neonates increased their circulating ketones by two- to threefold and restored near-normal glycemia (51 +/- 9 and 76 +/- 8 mg/dl) and production of glucose (6.7 +/- 0.7 and 6.6 +/- 0.8 mg.kg-1.min-1) in the hypotrophic and premature vs. normals (8.7 +/- 0.7 mg.kg-1.min-1). Individual rates of glucose production correlated with ketone concentrations (P less than 0.02). We conclude that the hypoglycemia characterizing low birth weight neonates is primarily due to impaired glucose production. That exogenous lipids were able to increase glucose production indicates that fatty acid oxidation plays an important glucoregulatory role in the human newborn.

Diffuse storage of vegetal wax hydrocarbons of dietary origin. Pathologic and chemical findings in a case

A 55-year-old man died suddenly, after presenting with unstable angina and an asymptomatic micronodular pulmonary pattern. Autopsy revealed storage of a crystallized fatty substance in the lymph nodes, liver, spleen, adrenal glands, and lungs. In the latter organ, the deposition formed foreign body granulomas, accounting for the radiographic appearance. Mass spectrometry identified the fatty substance as straight-chain saturated hydrocarbons (n-alkanes) of carbon-29 and carbon-31 atoms, which are naturally present in the cuticular wax of many vegetals. The case history and the elimination as causal agent of products manipulated in the patient's work led to the conclusion that the storage was due to excessive consumption of apples, and to a lesser degree of Brussels sprouts. We present the light-microscopic findings and the principal biochemical results. Pathogenic mechanisms are described. As far as we are aware, this is the only observation of vegetal alkane storage to be described to date.

A new human pathology with visceral accumulation of long-chain n-alkanes; tissue distribution of the stored compounds and pathophysiological hypotheses

This report deals with a new human disorder characterized by the accumulation of plant long-chain n-alkanes in viscera of a human patient. Lipid analysis of tissues from an adult male after sudden death (affected with diffuse visceral granuloma containing lipophilic crystallized material) showed the presence of abnormal compounds identified as long-chain n-alkanes with 29 (n-nonacosane), 31 (n-hentriacontane) and 33 carbons (n-tritriacontane). Study of n-alkane distribution in patient tissues showed a major accumulation in lumbo-aortic lymph nodes, adrenal glands, lung (the highest levels were found in lung granulomas) and liver; significantly lower amounts were detected in myocardium and kidney, whereas no detectable level was found in brain. On the basis of the structural composition and of the tissue distribution of the accumulated n-alkanes, their dietary (plant) origin and the pathophysiological mechanism of the storage are discussed.

Peripheral neuropathy associated with erythrophagocytic lymphohistiocytosis

A 12 year old patient who developed clinical, biochemical and histological features of erythrophagocytic lymphohistiocytosis is described. In contrast to previously reported cases, the prominent neurological feature was a subacute sensorimotor polyneuropathy. Sural nerve biopsy showed a marked reduction of myelinated fibres and severe axonal lesions, absence of histiocyte infiltration and deposits of IgM along the epineurium. In addition to the hypertriglyceridaemia previously described in this condition, an elevation of plasma very long-chain fatty acids and phytanic acid was found which suggests a transient impairment of peroxisomal functions.

Prenatal diagnosis of propionic acidemia in chorionic villi by direct assay of propionyl CoA carboxylase

Prenatal diagnosis of propionic acidemia was achieved by the direct assay of propionyl CoA carboxylase in chorionic villi. The diagnosis was confirmed by determination of methylcitrate in amniotic fluid and measurement of propionyl CoA carboxylase in the liver from the abortion. Discrepancy between [14C]-propionate incorporation into protein of chorionic villi or cultured chorionic cells and propionyl CoA carboxylase activity is reported.

Abnormal n-nonacosane storage in humans: detection by gas chromatography/mass spectrometry of tissue extracts

We report a case of n-nonacosane storage disease, which went undiagnosed until the death of a 55-year-old farmer. Clinical, histological, and biochemical features are discussed. n-Nonacosane storage was identified by gas chromatographic-mass spectrometric analysis of different tissue extracts, n-nonacosane concentration reaching 1.2 mg g-1 of lung tissue and 0.32 mg g-1 of liver tissue. It was possible to rule out a work-induced intoxication, and n-nonacosane storage appeared to be accounted for by a lifelong, heavy consumption of unpeeled apples and Brussels sprouts.

Immediate prenatal diagnosis of Zellweger syndrome by direct measurement of very long chain fatty acids in chorionic villus cells

We report a gas chromatographic-mass spectrometric method which allows the very long chain fatty acids content of trophoblastic tissue to be directly measured in samples collected by biopsy between 8 and 11 weeks of gestation. This method has been successfully applied to the detection of fetal Zellweger syndrome in two pregnant women who had previously delivered affected infants. In one of them, increased concentrations of C26:0 (0.254 versus 0.108 +/- 0.035 microgram/mg proteins) and C24:0 (1.32 versus 0.815 +/- 0.325 microgram/mg proteins) in trophoblast indicated that the fetus had Zellweger syndrome, a diagnosis confirmed by pathological findings after abortion. In the second case, the pregnancy was allowed to proceed, on the basis of normal concentrations of very long chain fatty acids in trophoblastic tissue, and its outcome was actually a healthy newborn.

Efficiency of substitution of 2-ketoisocaproic acid and 2-ketoisovaleric acid in the diet of normal and uremic growing rats

Effects of various intakes of the ketoanalogues of leucine (KICA) and valine (KIVA) on growth, nitrogen, and urea excretion were examined and compared to those of an optimal intake (A) of the corresponding amino acids. Diet KICA and KIVA contents varied from 1 to 4 times A. In controls, growth was significantly reduced with equimolar substitution, corrected with twice A, and unchanged at higher levels. Doubling KICA corrected growth except with substantial anorexia. In uremic rats fed KIVA, growth was corrected at twice A. Low-KICA diets reduced plasma-leucine level; higher KICA diets normalized plasma leucine and revealed branched-chain amino acid (BCAA) antagonism. Changes in 2-ketoacids were unrelated to those of BCAA. In uremia, KICA decreased plasma and urinary urea without changing nitrogen retention. Ketoacid substitution for amino acids was 50% efficient in normal rats and not altered by uremia. BCKAs, specifically KICA, could modify urea metabolism.

Pulmonary lipogranulomatosis due to excessive consumption of apples

A 55-year-old man was admitted for treatment of unstable angina. Chest x-ray films showed a micronodular pattern, but there were no respiratory symptoms. Autopsy, carried out following sudden death, revealed pulmonary granulomas surrounding lipid crystals. The same crystals were found elsewhere: lymph nodes, spleen, liver, adrenal glands, and were composed of aliphatic hydrocarbons of vegetal origin, mainly C29H60. Investigation of the case history revealed excessive consumption of apples, to which the hydrocarbon deposition could be attributed, since C29H60 is a natural constituent of the cuticular wax in apple peel. This is a unique example of pulmonary granulomatosis due to storage of vegetal hydrocarbons of dietary origin.

Neurological deterioration and lactic acidemia in biotinidase deficiency. A treatable condition mimicking Leigh's disease

A six-month-old girl with chronic lactic acidosis and neurological deterioration is described, who underwent a sudden severe decompensation during her initial neurological investigations. She responded dramatically to biotin therapy. The diagnosis of late onset multiple carboxylase deficiency due to biotinidase deficiency was confirmed. This entity should be considered in the differential diagnosis of hyperlactacidemic encephalopathies.

Mass spectrometric identification of 2-hydroxy-sebacic acid in the urines of patients with neonatal adrenoleukodystrophy and Zellweger syndrome

The urines of children with neonatal adrenoleukodystrophy and Zellweger syndrome contained an excess of unusual even- and odd-numbered dicarboxylic acids with a chain length of from 5 to 15 carbon atoms, as well as 2-hydroxy-compounds, including 2-hydroxy-isocaproate, 2-hydroxy-glutarate and 2-hydroxy-sebacate. The latter product, not previously found in metabolic diseases, appears as an additional useful marker of these peroxisomal disorders.

Medium- and long-chain dicarboxylic aciduria in patients with Zellweger syndrome and neonatal adrenoleukodystrophy

This study reports that patients with neonatal adrenoleukodystrophy and Zellweger syndrome excrete a very peculiar pattern of organic acids. Dicarboxylic acids with an even number of carbon atoms (adipic, suberic, sebacic, 2- and 3-hydroxy-sebacic, hexadecanedioic), as well as with an odd number of carbon atoms (pimelic, azelaic, un-, tri-, and pentadecanedioic) were found in excess in the urines of six patients with neonatal adrenoleukodystrophy and one with Zellweger syndrome. The accumulation of dicarboxylic acids, reflecting an impairment of their beta-oxidation in mitochondria and/or peroxisomes, thus appears as an additional useful marker of these peroxisomal diseases.

Neonatal adrenoleukodystrophy

Nine cases of neonatal adrenoleukodystrophy are described. All patients had abnormal facial features, moderate to severe hypotonia, hepatomegaly, and retinitis pigmentosa. The clinical course was rapidly progressive in six cases and more protracted in three others. Biological signs of adrenal insufficiency were present in five cases. CT scan showed a demyelinating process in four patients. Trilamellar inclusions were found in the liver of four cases and dark and complex lipidic inclusions in three other cases. In the three necropsied patients there was severe alteration of the white matter involving particularly the cerebellum in two cases. Gyral and cytoarchitectonic disturbances were absent in all three cases. Increased plasma levels of very long chain fatty acids (8/8), phytanic acid (7/8) and bile fluid trihydroxycoprostanic acid (2/4) confirmed the deficiency of multiple peroxisomal enzymes. Clinical, histopathological and biochemical findings of these nine cases are compared to those reported in other neonatal adrenoleukodystrophy cases and to those of other neonatal peroxisomal disorders, that is cerebro-hepato-renal syndrome of Zellweger and infantile Refsum's disease.

Medium-chain acyl-CoA dehydrogenase deficiency in two siblings with a Reye-like syndrome

An increasing number of reports indicate that patients with some inherited metabolic diseases may have symptoms resembling those of Reye syndrome. We describe two siblings who developed a Reye-like syndrome at ages 16 and 18 months, respectively, after a viral illness and salicylate therapy. Both had fasting hypoglycemia and hypoketonemia. At the time of the acute episode and after ingestion of a medium-chain triglyceride load, one of them excreted large amounts of abnormal metabolites derived from the omega- and (omega-1)-oxidation of medium-chain fatty acids. Medium-chain acyl-CoA dehydrogenase activity was lower than 20% of control values in fibroblasts from both patients. This enzyme defect should be considered in children with a Reye-like syndrome with these distinctive manifestations.

The cerebro-hepato-renal (Zellweger) syndrome: lamellar lipid profiles in adrenocortical, hepatic mesenchymal, astrocyte cells and increased levels of very long chain fatty acids and phytanic acid in the plasma

Clinical, radiological, histological and biochemical aspects of two cases of cerebro-hepato-renal syndrome (CHRS) are reported. CT scan disclosed a demyelinating process and gyral abnormalities reflecting the observed neuropathological findings. Trilamellar and lamellar inclusions were found in brain astrocytes, hepatic mesenchymal and adrenal cells. The morphologic features of these inclusions are similar to those observed in childhood adrenoleukodystrophy, neonatal adrenoleukodystrophy and infantile Refsum's disease. In the two CHRS patients, increased plasma levels of very long chain fatty acids (C26:1, C26:0) and phytanic acid were in the same range as those observed in seven other instances of neonatal adrenoleukodystrophy. The presence of increased plasma levels of phytanic acid in these disorders suggests that phytanate oxidase activity is, at least, partially located in peroxisomes.

Capillary gas-liquid chromatographic-mass spectrometric measurement of very long chain (C22 to C26) fatty acids in microliter samples of plasma

In order to quantify accurately the plasma content of very long chain fatty acids, we have developed a selected ion monitoring gas-liquid chromatographic-mass spectrometric micromethod which allows all of these acids (22:0, 24:1, 24:0, 26:1, and 26:0) to be determined simultaneously in the same 0.5-ml plasma sample; 17:0 and 27:0 fatty acids are used as assay internal standards. For plasma samples in the range equivalent to the various very long chain fatty acid physiological concentrations, assay precision was +/- 2%. The present method has been successfully applied to the biological recognition of patients with adrenoleukodystrophy, their heterozygote relatives, and of cerebro-hepato-renal syndrome and neonatal adrenoleukodystrophy.