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Biomedical subjects

L Sweetman

Publications and source records attributed to L Sweetman.

At least 73 records · Page 4Linked to original sources
PubMed1988

Mevalonate kinase deficiency in a child with cerebellar ataxia, hypotonia and mevalonic aciduria.

Mevalonate kinase deficiency has been documented in an 8-year-old child who presented with cerebellar ataxia, hypotonia and mevalonic aciduria. The activity of mevalonate kinase in extracts of cultured skin fibroblasts derived from the patient was approximately 2% of the mean value for controls. Family studies were carried out on the mother, the father and a sister, all of whom were clinically well. Mevalonate kinase activity in extracts of cultured skin fibroblasts and transformed lymphoblasts derived from the parents of the patient were 43%-52% of the mean control values. These data are consistent with an autosomal recessive mode of inheritance for mevalonate kinase deficiency.

Carboxy-Lyases↗
PubMed1988

3-Methylglutaconic aciduria: a phenotype in which activity of 3-methylglutaconyl-coenzyme A hydratase is normal.

3-Methylglutaconic aciduria has been found in two distinct syndromes. In one there is deficient activity of 3-methylglutaconyl coenzyme A hydratase, and the only clinical manifestation observed has been retardation of speech development. In the other, which includes a majority of the patients studied, we document that the activity of this enzyme in fibroblast extracts is normal. The phenotype of this disorder is one of profound neurological impairment with retarded psychomotor development, hypotonicity and/or spasticity, convulsions or EEG abnormalities, and sensorineural changes in the eye and ear.

Chemical Phenomena↗
PubMed1987

New diagnostic techniques for the detection of organic acidemias.

We describe an improved procedure for the extraction of organic acids which is equally suitable for urine, plasma and amniotic fluid and gives similar high recoveries for a wide variety of organic acids, without interferences from phosphate, sulfate, or urea. Internal standards are added, the oxoacids are converted to the pentafluorobenzyloximes; the sample is concentrated, acidified, chromatographed on a small column of silicic acid, and the effluent neutralized and dried. After forming the trimethylsilyl derivatives, gas chromatography is done on a 0.53 mm X 30 m low-polarity bonded-phase fused silica capillary column. For gas chromatographic-mass spectrometric quantification, the peak areas at the m/z of a characteristic fragment ion for each acid relative to the peak areas of ions of the internal standards are related to standard curves.

Adult↗
PubMed1987

Short-chain acyl-coenzyme A dehydrogenase deficiency. Clinical and biochemical studies in two patients.

We describe two patients with short-chain acyl-coenzyme A (CoA) dehydrogenase (SCADH) deficiency. Neonate I excreted large amounts of ethylmalonate and methylsuccinate; ethylmalonate excretion increased after a medium-chain triglyceride load. Neonate II died postnatally and excreted ethylmalonate, butyrate, 3-hydroxybutyrate, adipate, and lactate. Both neonates' fibroblasts catabolized [1-14C]butyrate poorly (29-64% of control). Neonate I had moderately decreased [1-14C]octanoate catabolism (43-60% of control), while neonate II oxidized this substrate normally; both catabolized radiolabeled palmitate, succinate, and/or leucine normally. Cell sonicates from neonates I and II dehydrogenated [2,3-3H]butyryl-CoA poorly (41 and 53% of control) and [2,3-3H]octanoyl-CoA more effectively (59 and 95% of control). Mitochondrial acyl-CoA dehydrogenase (ADH) activities with butyryl- and octanoyl-CoAs were 37 and 56% of control in neonate I, and 47 and 81% of control in neonate II, respectively. Monospecific medium-chain ADH (MCADH) antisera inhibited MCADH activity towards both butyryl- and octanoyl-CoAs, revealing SCADH activities to be 1 and 11% of control for neonates I and II, respectively. Fibroblast SCADH and MCADH activities were normal in an adult female with muscular SCADH deficiency.

3-Hydroxybutyric Acid↗
PubMed1987

Clinical and biochemical variation and family studies in the multiple acyl-CoA dehydrogenation disorders.

We report clinical and biochemical studies in patients with multiple acyl-CoA dehydrogenation disorders (MAD) and their parents. A severely affected (MAD:S) patient presented with neonatal acidosis leading to death and excreted a wide range of straight- and branched-chain acyl CoA derivatives. Two patients with mild variants of the same disorder (MAD:M) presented with neurologic abnormalities, acidotic coma, and/or poor growth; they primarily excreted ethylmalonate and variable amounts of adipate. Fibroblasts from the MAD:S patient demonstrated severely defective radiolabeled substrate oxidation, while the MAD:M cells had milder oxidative defects. Fibroblasts from two other MAD:M and six other MAD:S patients demonstrated analogous defects in substrate oxidation. As a group, MAD:S cells deficient in electron transfer flavoprotein:ubiquinone oxidoreductase had significantly lower residual oxidative activities than did MAD:S cells deficient in electron transfer flavoprotein. Fibroblasts from the parents of four MAD:S patients oxidized radiolabeled substrates significantly less effectively than did normal infant controls but were indistinguishable from normal adult cells. We found relatively higher residual oxidative activities in maternal than in paternal cells. Amniocytes from a fetus at risk for MAD:S catabolized labeled substrates normally; the infant has been clinically and biochemically normal up to 30 months of age.

Acyl-CoA Dehydrogenase↗
PubMed1987

Pharmacologic amino acid acylation in the acute hyperammonemia of propionic acidemia.

An infant with propionic acidemia presented at one month of age with hyperammonemic coma. Treatment by two double-volume exchange transfusions did not have an appreciable effect, but hemodialysis led to a substantial reduction of the serum concentration of ammonia on two occasions. Nevertheless, continued therapy with sodium benzoate, arginine-HCl, carnitine and lactulose did not have any observable effect on the blood concentration of ammonia. Treatment with sodium phenylacetate was followed by a reduction in serum concentrations of ammonia to normal levels which were maintained. These observations demonstrate the dramatic reduction in serum concentrations of ammonia that may be obtained in patients with organic acidemia by hemodialysis. They suggest that pharmacologic acylation therapy with phenylacetate may be of lasting benefit in the management of this complication.

Acylation↗
PubMed1986

Mevalonic aciduria--an inborn error of cholesterol and nonsterol isoprene biosynthesis.

A two-year-old boy presented with severe failure to thrive, developmental delay, anemia, hepatosplenomegaly, central cataracts, and dysmorphic features. Quantitative analyses of urinary organic acids revealed massive excretion of mevalonic acid, a metabolic precursor of cholesterol and nonsterol isoprenes: 46,000 to 56,200 mmol per mole of creatinine, as compared with 0.2 to 0.3 mmol per mole in normal children. The mevalonic acid concentration in plasma was also greatly increased at 440 mumol per liter (normal, less than 0.05). The activity of mevalonate kinase, the enzyme that catalyzes the first step in mevalonate metabolism, was severely deficient in the patient's fibroblasts, lymphocytes, and lymphoblasts. In the subsequent pregnancy of the patient's mother, gas chromatography-mass spectrometry demonstrated a marked elevation of mevalonic acid in the mother's urine and a 3000-fold elevation, as compared with control levels in the amniotic fluid, suggesting that the fetus was affected. The diagnosis was confirmed by demonstration of the deficiency of mevalonate kinase in amniocytes and ultimately in liver from the abortus. Intermediate activities of the enzyme in both parents indicated an autosomal recessive mode of inheritance. These observations identify an inherited disorder of cholesterol and nonsterol isoprene biosynthesis in humans.

Amniotic Fluid↗
PubMed1986

Rett syndrome revisited: a patient with biotin dependency.

A patient with Rett syndrome (cerebral atrophy associated with hyperammonemia) was studied. Primary defects of urea cycle enzymes were excluded as causes of the disorder. The analysis of urinary organic acids showed a moderate increase of lactate, methylcitrate, tiglyglycine and 3-hydroxisovalerate, indicating an abnormality of multiple carboxylases. Biotin supplementation reversed the urinary abnormalities. In fibroblasts grown with a low biotin medium propionylCoA and 3-methylcrotonylCoA carboxylase activities were reduced. Holocarboxylase synthetase activity was normal (Vmax and Km). Surprisingly the biotinidase in fibroblasts was not decreased. The data indicate that some patients with Rett syndrome might suffer from a biotin-dependent defect of unknown nature.

Amino Acids↗
PubMed1986

3-Ketothiolase deficiency.

Two patients have been studied in whom the activity of the short chain-length-specific mitochondrial 3-ketothiolase was found to be deficient. Use of a range of 3-ketoacyl-CoA substrates showed that the other 3-ketothiolase isoenzymes were normal in each case. Both patients had episodic ketosis and metabolic acidosis. One patient had substantial evidence of damage to the central nervous system and two siblings who had died of the disease. The organic aciduria was characterized by the excretion of 2-methyl-3-hydroxybutyric acid and tiglyglycine. In one patient the organic aciduria was very subtle and was masked during the presence of ketosis, but it was clarified by an isoleucine load after recovery from ketosis.

3-Hydroxybutyric Acid↗
PubMed1986

Deficiency of 3-methylglutaconyl-coenzyme A hydratase in two siblings with 3-methylglutaconic aciduria.

We studied two patients with 3-methylglutaconic aciduria in order to determine the molecular defect. A new assay for 3-methylglutaconyl-coenzyme A (CoA) hydratase has been developed in which the substrate, [5-14C]3-methylglutaconyl-CoA, was synthesized using 3-methylcrotonyl-CoA carboxylase purified from bovine kidney. In this assay the products of the reaction are isolated by reverse-phase high performance liquid chromatography and the rates of conversion from substrate are measured. The Michaelis constant for 3-methylglutaconyl-CoA in normal fibroblasts was 6.9 mumol/liter. The mean activity of 3-methylglutaconyl-CoA hydratase in control fibroblasts was 495 pmol/min per mg protein. In the two patients the values were 11 and 17 pmol/min per mg protein, or 2-3% of normal.

Amino Acid Metabolism, Inborn Errors↗
PubMed1986

Metabolism of branched-chain amino acids in fibroblasts from patients with maple syrup urine disease and other abnormalities of branched-chain ketoacid dehydrogenase activity.

The metabolism of branched-chain amino acids was studied in cultured fibroblasts from patients with branched-chain ketoacid dehydrogenase deficiency using 1-14C- and UL-14C-leucine and valine. The formation of 14CO2 from 1-14C-valine or 1-14C-leucine was 1-3% of normal. In fibroblasts of patients with associated lactic acidemia the values were 4-29% of control. Analysis of organic acid products revealed that in both patients and controls the amount of labeled alpha-ketoisovalerate recovered after incubation with 1-14C-valine was one-third of the amount of alpha-ketoisocaproate recovered after incubation with 1-14C-leucine. Very little alpha-hydroxyisocaproate was produced, while the amount of alpha-hydroxyisovalerate was about 10% of the alpha-ketoisovalerate. Unexpectedly beta-hydroxyisobutyrate was found to be the major metabolic product of UL-14C-valine in normal fibroblasts. Large accumulations of beta-hydroxyisovalerate were found in normal fibroblasts using UL-14C-leucine. There were little or no conversions to these compounds in fibroblasts of patients with branched-chain ketoacid dehydrogenase deficiency. There were substantial conversions in the patients in whom dehydrogenase deficiency was associated with lactic acidemia.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1986

Multiple carboxylase deficiency due to deficiency of biotinidase.

A patient with biotinidase deficiency was studied in whom the first admission to hospital for acidosis occurred at 5 years of age. Sensorineural abnormalities of the optic and auditory nerves antedated diagnosis and treatment with biotin, and these sensory losses did not resolve with treatment. The other clinical manifestations of the disease were highly responsive to biotin. Biotinidase was assayed using 14C-labeled natural substrate. The activity in the patient approximated 1% of the control level.

Amidohydrolases↗
PubMed1985

Immunoextraction of lipoamide dehydrogenase from cultured skin fibroblasts in patients with combined alpha-ketoacid dehydrogenase deficiency.

Combined deficiency of the pyruvate, alpha-ketoglutarate and branched-chain keto acid dehydrogenase complexes is a rare condition in which activity of lipoamide dehydrogenase is either reduced or grossly deficient. Activities in three cell strains from patients with excretion of branched chain ketoacids and alpha-ketoglutarate and lactic-acidemia showed decreased levels of the three alpha-ketoacid dehydrogenases. Lipoamide dehydrogenase activity was 5% of normal in one cell stain and 50-60% in the other two. Antiserum raised against lipoamide dehydrogenase was used to immunoprecipitate labelled lipoamide dehydrogenase from fibroblasts grown on [35S]methionine. After separation of cell proteins from control fibroblasts by sodium dodecyl sulphate/polyacrylamide gel electrophoresis and fluorography, a prominent 55 kilodalton band was evident in cell extracts treated with the antiserum which corresponded to lipoamide dehydrogenase. In the cell lines from patients with combined alpha-ketoacid dehydrogenase deficiency immunoprecipitation of lipoamide dehydrogenase showed that this protein was present in similar amounts to that seen in control cell lines and was also of the correct molecular weight.

Antibodies, Monoclonal↗
PubMed1985

The occurrence of lactyl lactate and succinyl lactate in the urine of patients screened for inherited metabolic disease.

The gas chromatographic and mass spectrometric identification of lactyl lactate and succinyl lactate, both present in human urine, is described. In the gas chromatogram lactyl lactate (as TMS derivative) presented as two peaks: the L,L- and/or D,D-form as well as the D,L- and/or the L,D-enantiomer. Both L- and D-lactyl succinate were excreted simultaneously. Lactyl lactate was observed in many patients; succinyl lactate only a few times and only together with lactyl lactate. No correlation with (endogenous) urinary lactate could be established. Presumably these compounds are products of the intestinal bacteria.

Adult↗