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C Jakobs

Publications and source records attributed to C Jakobs.

At least 55 records · Page 3Linked to original sources
PubMed2004

5-Methyltetrahydrofolic acid and folic acid measured in plasma with liquid chromatography tandem mass spectrometry: applications to folate absorption and metabolism.

We describe a liquid chromatography (LC) tandem mass spectrometry (MS-MS) method for the determination of 5-methyltetrahydrofolic acid (5-methylTHF) and folic acid concentrations and enrichments in human plasma. It was used to study absorption and initial metabolism in five volunteers with two simultaneously administered oral test doses ([(13)C(6)]folic acid in capsules and [(2)H(2)]folic acid in a drink). [(13)C(5)]5-methylTHF and [(2)H(4)]folic acid were used as internal standards. Plasma samples (2 ml) were purified using folate binding protein affinity columns, followed by a concentration step. After LC separation, folates were detected using positive electrospray ionization MS-MS under multiple reaction monitoring conditions. Calibrations were linear for 5-methylTHF over the range 1.2 x 10(-11) (=limit of detection) to 3.2 x 10(-7)mol/L and for folic acid over the range 5 x 10(-10) (=limit of detection) to 4.5 x 10(-8)mol/L. For 5-methylTHF concentration in plasma, intraassay coefficient of variation was within 8.6% (and for unlabeled 5-methylTHF it was within 2.8%) and interassay coefficient of variation was within 9.0%. For folic acid concentrations these coefficient of variations were within 7.5% and within 6.5%, respectively. The [(13)C(6)] and [(2)H(2)] isotopomers of folic acid and 5-methylTHF were measured in the plasma of each volunteer for 8h. After accounting for the time delay due to capsule opening, the modeling results showed no significant differences in absorption time, first pass effect, and elimination rate in the folic acid test doses in capsule or drink. We conclude that LC-MS-MS offers increased sensitivity for quantification of plasma concentrations and enrichments of 5-methylTHF and folic acid and is applicable to stable-isotope studies in humans.

Administration, Oral↗
PubMed2004

Photosensitive absence epilepsy with myoclonias and heterozygosity for succinic semialdehyde dehydrogenase (SSADH) deficiency.

OBJECTIVE: Succinic semialdehyde dehydrogenase (SSADH) deficiency is a neurometabolic disorder characterized by excessive GABA levels and seizures. There has been no clinical phenotype described to date with heterozygosity for SSADH deficiency. METHODS: A patient heterozygous for SSADH deficiency presented with absence and myoclonic seizures. EEG monitoring and enzymatic, metabolic, and molecular studies for SSADH were obtained on the patient and family members. RESULTS: EEG recordings yielded generalized 3-4 Hz spike-wave paroxysms and trains of multiple spikes in the heterozygous patient, and photosensitivity in the heterozygous patient and parent as well as in the sibling with homozygous deficiency. The heterozygous patient and parents did not manifest 4-OH-butyric aciduria but SSADH levels were low and a splice site mutation of the SSADH gene was identified in each. CONCLUSIONS: Heterozygosity for SSADH deficiency may be associated with an epilepsy syndrome characterized by absence and myoclonic seizures, photoparoxysmal EEG and generalized epileptiform discharges SIGNIFICANCE: Heterozygous SSADH deficiency may be suspected, given an appropriate family history in the setting of an apparently idiopathic generalized epilepsy. Pathogenic explanations may relate to regional elevations in GABA or GHB concentrations.

Adolescent↗
PubMed2004

Seizure evolution and amino acid imbalances in murine succinate semialdehyde dehydrogenase (SSADH) deficiency.

Mice with targeted deletion of the GABA catabolic enzyme succinic semialdehyde dehydrogenase (SSADH) manifest lethal tonic-clonic seizures, amenable to pharmacologic rescue, at 3-4 weeks of life. In the current report, we characterized amino acid profiles in SSADH(-/-) brain utilizing whole brain and regional extracts (frontal and parietal cortex, hippocampus, and cerebellum) to develop hypotheses concerning epileptogenesis. Of 35 amino acids quantified, we found significant dysregulation in SSADH(-/-) mice for 11 (GABA, glutamate, glutamine, alanine, aspartate, serine, taurine, cystathionine, methionine, homocarnosine, and arginine) as compared to age-matched littermates both before, and following, the period of generalized convulsive seizures and status epilepticus. Our results reveal imbalanced amino acid levels potentially involved in the transition from absence seizures to generalized convulsive seizures resulting in SSADH(-/-) mice. We conclude that the SSADH(-/-) mouse represents a unique epileptic model with the potential to reveal novel aspects of excitatory/inhibitory interactions in the genesis of seizures.

Aldehyde Oxidoreductases↗
PubMed2004

The molecular basis of succinic semialdehyde dehydrogenase deficiency in one family.

Succinic semialdehyde dehydrogenase (SSADH) deficiency has predominantly neurological consequences, affecting psychomotor, speech and language development. Recently, two clinical reviews summarized the features of this disease and their relative frequency [Neurology 60 (2003) 1413; Ann. Neurol. 54 (2003) S73]. The molecular genetics of SSADH deficiency is still being explored. We describe the molecular basis of this defect in a Tunisian female child presenting with a mild phenotype. A small scale deletion in exon 10 of the gene led to a frameshift that predicts premature termination of the resulting putative protein. The parents were shown to be heterozygotes for this deletion, supporting its causative role.

Aldehyde Oxidoreductases↗
PubMed2004

Sedation with 4-hydroxybutyric acid: a potential pitfall in the diagnosis of SSADH deficiency.

Deficiency of succinic semialdehyde dehydrogenase (SSADH) is a rare neurometabolic disorder with accumulation of 4-hydroxybutyric acid (4-HBA) as a biochemical hallmark. We present a boy with an unresolved severe neurological disorder and intermittent elevation of 4-HBA in serum and CSF which was later shown to result from iatrogenic administration of 4-HBA for sedation purposes.

Aldehyde Oxidoreductases↗
PubMed2004

D-2-hydroxyglutaric aciduria and glutaric aciduria type 1 in siblings: coincidence, or linked disorders?

Glutaric aciduria type 1 (GA1) and D-2-hydroxyglutaric aciduria ( D-2-HGA) are cerebral organic acidurias characterized by the excretion of 3-hydroxyglutaric and D-2-hydroxyglutaric acids, respectively. GA1 is caused by a deficiency of glutaryl-CoA dehydrogenase encoded by the GCDH gene; the biochemical and genetic basis of D-2-HGA is unknown. We diagnosed GA1 in the son of consanguineous Palestinian parents, and D-2-HGA in his sister and brother. All three siblings were neurologically and developmentally normal. A small but abnormal increase in excretion of D-2-hydroxyglutaric acid was also found in the sibling with GA1. These observations suggested a possible pathophysiological link between these two disorders. The sibling with GA1 was homozygous whilst his siblings with D-2-HGA were heterozygous for a 1283 C>T missense mutation (T416I) in exon 11 of the GCDH gene. However, sequence analysis of the GCDH gene in 8 additional unrelated patients with D-2-HGA and 3 with combined D/ L-2-HGA did not reveal any pathogenic mutations. The biochemical and genetic basis of D-2-HGA remains to be determined.

Brain Diseases, Metabolic, Inborn↗
PubMed2004

Clinical presentations of patients with polyol abnormalities.

Since our description of a patient with leukoencephalopathy and highly elevated polyols in the brain and body fluids, we started screening for polyol abnormalities in patients highly suspected of a metabolic disorder. We identified four additional patients with consistent abnormalities in sugar and polyol profiles in body fluids. The clinical, neuroimaging, and biochemical findings of the five patients detected so far are described in the present paper. In four patients neurological problems dominated the clinical picture, whereas liver failure dominated in the other patient. The sugar and polyol profiles were abnormal in body fluids in all patients, but the profiles were different in individual patients. A deficiency of transaldolase was found in the patient presenting with liver failure. We were not able to identify the basic defect in the four patients with predominantly neurological problems. The differences in clinical picture, MRI abnormalities, and sugar and polyol profiles in these patients suggest that the underlying defects may be different. Whether the abnormal sugar and polyol profiles are directly related to the cause of disease via defects in polyol metabolism or transport remains to be elucidated.

Brain↗
PubMed2003

Changes in the ornithine cycle following ionising radiation cause a cytotoxic conditioning of the culture medium of H35 hepatoma cells.

Cultured H35 hepatoma cells release a cytotoxic factor in response to irradiation with X-rays. When the conditioned medium from irradiated cells is given to nonirradiated cells, growth is inhibited and followed by cell death, possibly apoptosis, Analysis of the conditioned medium reveals a dramatic change in the ornithine (urea) cycle components after the irradiation. A strong decrease in medium arginine is accompanied with parallel increases in ornithine, citrulline and ammonia. The high level of ammonia appears to be largely responsible for the observed cytotoxicity. The development of hyperammonia by irradiated cells and the related toxicity depend on the radiation dose and the number of cells seeded thereafter for the medium conditioning. Development of cytotoxicity by irradiated cells is completely prevented with the arginase inhibitor L-norvaline, in arginine-deficient medium or when citrulline replaces arginine. These preventive measures result in subtoxic ammonia levels.

Animals↗
PubMed2003

Plasma homocysteine and S-adenosylmethionine in erythrocytes as determinants of carotid intima-media thickness: different effects in diabetic and non-diabetic individuals. The Hoorn Study.

OBJECTIVE: Hyperhomocysteinemia is a risk factor for atherothrombosis. Through unknown mechanisms, individuals with type 2 diabetes appear particularly susceptible. We determined whether components of homocysteine metabolism are associated with intima-media thickness in individuals with and without type 2 diabetes. METHODS AND RESULTS: In a cross-sectional design, we studied 231 Caucasian individuals, 60.6% having type 2 diabetes. We measured fasting homocysteine, vitamin B6 and vitamin B12 in plasma, and folate, S-adenosylmethionine and S-adenosylhomocysteine in plasma and erythrocytes. A homocysteine concentration >12 micromol/l was associated with a greater intima-media thickness of +0.07 mm (95% CI, +0.01 to +0.13; P=0.03) among diabetic individuals and of -0.004 mm (95%CI, -0.08 to +0.07; P=0.92) among non-diabetic individuals. An erythrocyte S-adenosylmethionine concentration above >4000 nmol/l was associated with a smaller intima-media thickness of -0.04 mm (95%CI, -0.10 to +0.02; P=0.17) for diabetic individuals versus -0.12 mm (95%CI, -0.20 to -0.36; P=0.005) for non-diabetic individuals. CONCLUSIONS: With regard to carotid intima-media thickness, individuals with diabetes appear more susceptible to the detrimental effects of homocysteine than non-diabetic individuals. In addition, diabetic individuals may lack the protective effect on the vascular wall conferred by high concentrations of S-adenosylmethionine. These findings may help explain why hyperhomocysteinemia is an especially strong risk factor for atherothrombosis among individuals with type 2 diabetes.

Aged↗
PubMed2003

D-2-Hydroxyglutaric aciduria with absence of corpus callosum and neonatal intracranial haemorrhage.

We report D-2-hydroxyglutaric aciduria in a neonate with intracranial haemorrhage and absence of the corpus callosum. D-2-hydroxyglutaric acid was confirmed by specific chiral derivatization gas chromatography-mass spectrometry. Absence of the corpus callosum and spontaneous neonatal intracranial haemorrhage should raise the suspicion for metabolic disease, and especially organic acidurias.

Abnormalities, Multiple↗
PubMed2003

X-linked creatine transporter defect: an overview.

In 2001 we identified a new inborn error of metabolism caused by a defect in the X-linked creatine transporter SLC6A8 gene mapped at Xq28 (SLC6A8 deficiency, McKusick 300352). An X-linked creatine transporter defect was presumed because of (1) the absence of creatine in the brain as indicated by proton magnetic resonance spectroscopy (MRS); (2) the elevated creatine levels in urine and normal guanidinoacetate levels in plasma, ruling out a creatine biosynthesis defect; (3) the absence of an improvement on creatine supplementation; and (4) the fact that the pedigree suggested an X-linked disease. Our hypothesis was proved by the presence of a hemizygous nonsense mutation in the male index patient and by the impaired creatine uptake by cultured fibroblasts. Currently, at least 7 unrelated families (13 male patients and 13 carriers) with a SLC6A8 deficiency have been identified. Four families come from one metropolitan area. This suggests that SLC6A8 deficiency may have a relatively high incidence. The hallmarks of the disorder are X-linked mental retardation, expressive speech and language delay, epilepsy, developmental delay and autistic behaviour. In approximately 50% of the female carriers, learning disabilities of varying degrees have been noted.

Biological Transport↗
PubMed2003

S-adenosylhomocysteine and the ratio of S-adenosylmethionine to S-adenosylhomocysteine are not related to folate, cobalamin and vitamin B6 concentrations.

BACKGROUND: It is unclear whether homocysteine itself is causal in the pathogenesis of cardiovascular disease. Alternatively or additionally, the association between homocysteine and cardiovascular disease may be because of its metabolic precursor, S-adenosylhomocysteine, or of the ratio of S-adenosylmethionine to S-adenosylhomocysteine. Therefore, it is relevant to know how these moieties are interrelated, and whether, as is the case for homocysteine, they are influenced by blood levels of folate, cobalamin or vitamin B6. DESIGN: We cross-sectionally studied a population-based cohort of 97 Caucasian subjects aged 60-85 years. Concentrations of homocysteine, S-adenosylhomocysteine, S-adenosylmethionine, folate, cobalamin and vitamin B6 were measured in fasting blood samples. RESULTS: In multiple regression analysis, homocysteine was associated with vitamin B12 (per 50 pmol L-1 increase of cobalamin, change in homocysteine, -0.70 mmol L-1; 95% CI, -1.30 to -0.10 mmol L-1) and folate (per 100 nmol L-1 increase in erythrocyte folate, change in homocysteine, -0.68 mmol L-1; 95% CI -1.28 to -0.08 mmol L-1). S-adenosylhomocysteine, S-adenosylmethionine and the ratio of S-adenosylmethionine to S-adenosylhomocysteine were not associated with serum folate, cobalamin or vitamin B6, nor with erythrocyte folate. Furthermore, plasma homocysteine showed a negative correlation with the ratio of S-adenosylmethionine to S-adenosylhomocysteine in plasma (r = -0.27; P < 0.01) but not in erythrocytes. CONCLUSIONS: In contrast to homocysteine, the plasma concentrations of S-adenosylhomocysteine and the ratio of S-adenosylmethionine to S-adenosylhomocysteine were not associated with the folate, cobalamin and vitamin B6 concentrations in the present study. If these precursors in part explain why homocysteine is associated with cardiovascular disease, homocysteine-lowering treatment with B vitamins may be less effective than currently expected, at least in an elderly population.

Aged↗
PubMed2003

Glutaryl-CoA dehydrogenase deficiency: region-specific analysis of organic acids and acylcarnitines in post mortem brain predicts vulnerability of the putamen.

The neurometabolic disorder glutaryl-CoA dehydrogenase (GCDH) deficiency is biochemically characterised by an accumulation of the marker metabolites 3-hydroxyglutaric acid, glutaric acid, and glutarylcarnitine. If untreated, the disease is complicated by acute encephalopathic crises, resulting in neurodegeneration of vulnerable brain regions, in particular the putamen. 3-hydroxyglutaric acid is considered the major neurotoxin in this disease. There are only preliminary data concerning glutaric acid concentrations in the brains of affected children and the distribution of 3-hydroxyglutaric acid and glutarylcarnitine has not been described. In the present study, we investigated post mortem the distribution of 3-hydroxyglutaric and glutaric acids as well as glutarylcarnitine in 14 different brain regions, internal organs, and body fluids (urine, plasma, cerebrospinal fluid) in a 14-year-old boy. 3-Hydroxyglutaric acid showed the highest concentration (62 nmol/g protein) in the putamen among all brain areas investigated. The glutarylcarnitine concentration was also highest in the putamen (7.1 nmol/g protein). We suggest that the regional-specific differences in the relative concentrations of 3-hydroxyglutaric acid contribute to the pattern of neuronal damage in this disease. These results provide an explanatory basis for the high vulnerability of the putamen in this disease, adding to the strong corticostriatal glutamatergic input into the putamen and the high excitotoxic susceptibility of neostriatal medium spiny neurons.

Acidosis↗
PubMed2003

5,10-Methylenetetrahydrofolate reductase 677C-->T and 1298A-->C mutations are genetic determinants of elevated homocysteine.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Elevated plasma total homocysteine (tHcy) is a major risk for cardiovascular disease. A common 677C-->T mutation in the MTHFR gene results in decreased enzymic activity, and contributes to increased plasma tHcy, in association with low plasma folate. A recently described 1298A-->C mutation in the MTHFR gene clearly reduces MTHFR activity (although to a lesser extent than the 677C-->T) but its effect on plasma tHcy levels is not yet clear. AIM: To investigate the frequency of these two MTHFR polymorphisms in a Portuguese population, and to correlate the MTHFR genotype with the biochemical phenotype at the level of homocysteine and folate concentrations. DESIGN: Prospective population survey. METHODS: We studied 117 healthy volunteers (71 females, 46 males). The 677C-->T and 1298A-->C mutations were screened by PCR-RFLP. Levels of plasma tHcy and folate, and red blood cell folate, were determined. RESULTS: The allele frequencies of the 677C-->T and 1298A-->C mutations were 0.33 and 0.28, respectively. Homozygotes for the 677C-->T mutation had significantly elevated plasma tHcy and RBC folate levels and significantly lowered plasma folate concentrations than subjects without the mutation. The 1298A-->C mutation showed a significant effect on plasma tHcy, but not on plasma folate or RBC folate levels. DISCUSSION: The observed 677T allele frequency is not consistent with the idea of a north-south gradient as previously suggested. The 1298A-->C mutation is common in Portugal. Both MTHFR mutations showed effects on plasma tHcy levels.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed2002

Quantification of 3-hydroxyglutaric acid in urine, plasma, cerebrospinal fluid and amniotic fluid by stable-isotope dilution negative chemical ionization gas chromatography-mass spectrometry.

This paper describes a stable isotope dilution method for quantification of 3-hydroxyglutaric acid (3-HGA) in body fluids. The method comprises a solid-phase extraction procedure, followed by gas chromatographic separation and negative chemical ionization mass spectrometric detection. This method is selective and sensitive, and enables measurement of 3-HGA concentrations in urine-, plasma-, and CSF- samples of controls. The control ranges for 3-HGA were: urine 0.88-4.5 mmol/mol creatinine (n=12); plasma 0.018-0.10 micro mol/l (n=10), CSF 0.022-0.067 micro mol/l (n=10). We applied this method to measure 3-HGA in body fluids of three patients with glutaric aciduria type I. We also quantified 3-HGA in amniotic fluid of controls (range 0.056-0.11 micro mol/l; n=12) and in two samples from fetuses affected with glutaric aciduria type I.

Amniotic Fluid↗
PubMed2002

D-2-Hydroxyglutaric aciduria in a patient with a severe clinical phenotype and unusual MRI findings.

We report an infant with intermittent urinary excretion of D-2-hydroxyglutaric (D-2-OHG) acid who died at the age of 10 months from cardiogenic shock due to cardiomyopathy. High urinary concentrations of D-2-OHG and succinic acid, as well as increased levels of lactic acid were detected on three different occasions, whereas a normal urinary profile of organic acids was found on one occasion. The clinical findings of our patient consisted of generalized hypotonia, irritability, developmental delay, generalized tonic seizures, lethargy, cardiomyopathy, and respiratory distress. Cerebral MRI revealed bilateral lesions in the substantia nigra, the periaqueductal area, the medial part of the thalamus, the hypothalamus, the caudate nucleus, putamen and globus pallidus. This pattern is suggestive of a mitochondriopathy. However, respiratory chain enzyme activities were normal in fibroblasts. Exogenous supplementation of D-2-OHG acid strongly inhibited cytochrome-c oxidase activity in fibroblasts from the patient and from normal controls in vitro. The results suggest that our patient has an unusual form of D-2-hydroxyglutaric aciduria (D-2-OHGA), different from the patients published so far, and that the increase of lactic acid and some citric acid cycle intermediates encountered in some patients with D-2-OHGA may be due to a functional defect of the respiratory chain caused by D-2-OHG acid.

Brain↗
PubMed2002

Focal neurometabolic alterations in mice deficient for succinate semialdehyde dehydrogenase.

Metabolite profiling in succinate semialdehyde dehydrogenase (SSADH; Aldh5a1-/-) deficient mice previously revealed elevated gamma-hydroxybutyrate (GHB) and total GABA in urine and total brain and liver extracts. In this study, we extend our metabolic characterization of these mutant mice by documenting elevated GHB and total GABA in homogenates of mutant kidney, pancreas and heart. We quantified beta-alanine (a GABA homolog and putative neurotransmitter) to address its potential role in pathophysiology. We found normal levels of beta-alanine in urine and total homogenates of mutant brain, heart and pancreas, but elevated concentrations in mutant kidney and liver extracts. Amino acid analysis in mutant total brain homogenates revealed no abnormalities except for significantly decreased glutamine, which was normal in mutant liver and kidney extracts. Regional amino acid analysis (frontal cortex, parietal cortex, hippocampus and cerebellum) in mutant mice confirmed glutamine results. Glutamine synthetase protein and mRNA levels in homogenates of mutant mouse brain were normal. We profiled organic acid patterns in mutant brain homogenates to assess brain oxidative metabolism and found normal concentrations of Kreb's cycle intermediates but increased 4,5-dihydroxyhexanoic acid (a postulated derivative of succinic semialdehyde) levels. We conclude that SSADH-deficient mice represent a valid metabolic model of human SSADH deficiency, manifesting focal neurometabolic abnormalities which could provide key insights into pathophysiologic mechanisms.

Aldehyde Oxidoreductases↗