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R J Pollitt

Publications and source records attributed to R J Pollitt.

At least 19 recordsLinked to original sources
PubMed1992

Identification of urinary acylcarnitines using gas chromatography-mass spectrometry: preliminary clinical applications.

Many disorders of organic acid metabolism are associated with abnormalities in the levels of acylcarnitines excreted in urine. Profiling of urinary acylcarnitines allows diagnosis and characterisation of many acidurias and acidemias, monitoring dietary treatment of such patients, and elucidation of the metabolism of some exogenous acidic compounds. Urine (ca. 0.5 ml) was subjected to a simple work-up by ion-exchange chromatography, and the isolated acylcarnitines were derivatized by cyclization in 35 min to give volatile lactones that are compatible with gas chromatography-mass spectrometry using electron or chemical ionization. The feasibility of this new and affordable procedure has been confirmed by identifying urinary acylcarnitines in cases of medium-chain acyl-coenzyme A dehydrogenase deficiency, propionic acidemia and isovaleric acidemia.

Acylation↗
PubMed1992

Human liver long-chain 3-hydroxyacyl-coenzyme A dehydrogenase is a multifunctional membrane-bound beta-oxidation enzyme of mitochondria.

We have purified to homogeneity the long-chain specific 3-hydroxyacyl-CoA dehydrogenase from mitochondrial membranes of human infant liver. The enzyme is composed of non-identical subunits of 71 kDa and 47 kDa within a native structure of 230 kDa. The pure enzyme is active with 3-ketohexanoyl-CoA and gives maximum activity with 3-ketoacyl-CoA substrates of C10 to C16 acyl-chain length but is inactive with acetoacetyl-CoA. In addition to 3-hydroxyacyl-CoA dehydrogenase activity, the enzyme possesses 2-enoyl-CoA hydratase and 3-ketoacyl-CoA thiolase activities which cannot be separated from the dehydrogenase. None of these enzymes show activity with C4 substrates but all are active with C6 and longer acyl-chain length substrates. They are thus distinct from any described previously. This human liver mitochondrial membrane-bound enzyme catalyses the conversion of medium- and long-chain 2-enoyl-CoA compounds to: 1) 3-ketoacyl-CoA in the presence of NAD alone and 2) to acetyl-CoA (plus the corresponding acyl-CoA derivatives) in the presence of NAD and CoASH. It is therefore a multifunctional enzyme, resembling the beta-oxidation enzyme of E. coli, but unique in its membrane location and substrate specificity. We propose that its existence explains the repeated failure to detect any intermediates of mitochondrial beta-oxidation.

Acyl-CoA Dehydrogenase, Long-Chain↗
PubMed1992

Differential diagnosis of hydroxydicarboxylic aciduria based on release of 3H2O from [9,10-3H]myristic and [9,10-3H]palmitic acids by intact cultured fibroblasts.

Intact cultured fibroblasts from patients with deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase release 3H2O from [9,10-3H]myristic acid and [9,10-3H]palmitic acid more slowly than normal. The ratio of activity (palmitate/myristate) is also low and the expression (rate with palmitate2/(rate with myristate) gives good differentiation between affected and unaffected cells. In some patients who have shown hydroxydicarboxylic aciduria when unwell there is reduced 3H2O production from [9,10-3H]myristic and [9,10-3H]palmitic acids by intact cultured fibroblasts but normal 3-hydroxyacyl-CoA dehydrogenase activities in disrupted cells. The palmitate/myristate ratio is higher than in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency. The basic defect in these patients is still unknown but it is suggested that caution be used over the administration of medium-chain triglyceride.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

Possible deleterious effect of L-carnitine supplementation in a patient with mild multiple acyl-CoA dehydrogenation deficiency (ethylmalonic-adipic aciduria).

A patient with riboflavin-responsive mild multiple acyl-CoA dehydrogenation deficiency of the ethylmalonic--adipic aciduria type experienced a recurrence of spontaneous hypoglycaemic episodes whilst being given supplementary L-carnitine. This phenomenon is explicable in terms of the known biochemical features of this condition and suggests caution in the carnitine supplementation of patients with defective oxidation of medium- or short-chain fatty acyl-CoA esters. This patient excreted excessive phenylpropionylglycine after an oral phenylpropionic acid load. Thus the phenylpropionic acid loading test is not completely specific for primary medium-chain acyl-CoA dehydrogenase deficiency as has been supposed.

Acyl-CoA Dehydrogenases↗
PubMed1991

Atypical riboflavin-responsive glutaric aciduria, and deficient peroxisomal glutaryl-CoA oxidase activity: a new peroxisomal disorder.

Investigation of cultured skin fibroblasts in a patient with atypical riboflavin-responsive glutaric acidura revealed a marked deficiency of peroxisomal glutaryl-CoA oxidase. This is the first patient to be reported with glutaric aciduria caused by a peroxisomal rather than a mitochondrial dysfunction. This enzyme appears to be specific for glutaryl-CoA, as lauryl-CoA and dodecanedioyl-CoA oxidase activities in the fibroblasts were both normal. The urinary excretion of glutaric acid (0.5 mmol mmol creatinine-1) suggests that the flux through this pathway is considerably less than the mitochondrial flux through glutaryl-CoA dehydrogenase. The elevated glutaric acid excretion (to 0.8 mmol mmol creatinine-1) in response to lysine loading suggests that lysine is a precursor.

Acyl-CoA Oxidase↗
PubMed1991

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency.

We describe the clinical features and biochemical findings of two patients with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency. Both children presented with an acute metabolic crisis. Both had hypoglycemia and excreted even-chain unsubstituted dicarboxylic and 3-hydroxy-dicarboxylic acids in the urine. Measurement of the enzymes of fatty acid oxidation in cultured skin fibroblasts showed low activity of long-chain 3-hydroxyacyl-CoA dehydrogenase, but normal activity of short-chain 3-hydroxyacyl-CoA dehydrogenase. The defect was further characterized by immunoprecipitating the short-chain enzyme using monospecific antibodies. It is probably inherited as an autosomal recessive trait, inasmuch as intermediate enzyme activity was found in the fibroblasts from the parents of one child.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1990

Identification of a common mutation in patients with medium-chain acyl-CoA dehydrogenase deficiency.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is one of the most common recessively inherited metabolic diseases in man. We have studied fibroblast cultures obtained from three patients with MCAD deficiency by sequencing the entire coding region of MCAD mRNA. A single A to G nucleotide replacement which resulted in lysine329-to-glutamic acid329 substitution of the MCAD protein was identified in all cultures. Furthermore, this point mutation was present in 91% (31 of 34) of mutant MCAD alleles, indicating that the majority of cases with MCAD deficiency are caused by this type of mutation.

Acyl-CoA Dehydrogenase↗
PubMed1990

Trichothiodystrophy, mental retardation, short stature, ataxia, and gonadal dysfunction in three Moroccan siblings.

Three sibs, a boy and two girls, born to Moroccan consanguineous parents, were affected with a syndrome characterized by brittle hair, mental retardation, short stature, ataxia, and gonadal dysfunction. The hair in these three patients displayed the morphological and biochemical hallmarks of trichothiodystrophy (TTD). Gonadal function tests showed abnormal gonadotropic responses to LHRH, consistent with delayed puberty in the male and ovarian failure in both females. Comparison with previously reported cases of TTD associated with mental retardation suggests genetic heterogeneity, although specific biochemical markers are needed in order to answer this question.

Abnormalities, Multiple↗
PubMed1990

A comparison of [9,10-3H]palmitic and [9,10-3H]myristic acids for the detection of defects of fatty acid oxidation in intact cultured fibroblasts.

The production of tritiated water from [9,10-3H]myristic acid can be used as a screening assay for the detection of medium-chain acyl-CoA dehydrogenase deficiency, multiple acyl-CoA dehydrogenation defects (glutaric aciduria type 2 and ethylmalonic-adipic aciduria types), and some types of hydroxydicarboxylic aciduria. Comparison with the release of tritiated water from [9,10-3H]palmitic acid may give an indication of the chain-length specificity of the metabolic defect. In a case of ethylmalonic-adipic aciduria such a prediction has been confirmed by examination of accumulated intermediates in the affected fibroblasts.

Acyl-CoA Dehydrogenase↗
PubMed1990

Analysis of abnormal urinary metabolites in the newborn period in medium-chain acyl-CoA dehydrogenase deficiency.

In order to determine which are useful early diagnostic markers for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, we have analysed urine from an asymptomatic neonate. Profiling of urinary organic acids followed by peak confirmation by electron impact mass spectrometry revealed a high suberate/adipate ratio (greater than 1.0) and the presence of n-hexanoylglycine (HG). Acylcarnitine analysis by fast atom bombardment mass spectrometry (FAB-MS) was inconclusive, but FAB-MS/MS (tandem mass spectrometry) revealed diagnostic amounts of octanoylcarnitine and hexanoylcarnitine. Quantitative analysis of acylglycines by stable isotope dilution and chemical ionization mass spectrometry revealed a 30-fold increase in HG and increased suberylglycine, but no increase in 3-phenylpropionylglycine.

Acyl-CoA Dehydrogenase↗
PubMed1990

D(+)-glyceric aciduria: etiology and clinical consequences.

A family comprising mother, father, and five children is described. Four of the children were found to excrete massive amounts of D(+)-glyceric acid in their urine. This was verified by gas chromatography-mass spectrometry and the configuration determined by capillary gas chromatography of O-acetylated menthyl esters. The excretion ranged from 10.8 to 19.9 mmol/24 h. The remaining child and the parents showed no evidence of this unusual metabolite. The virtual absence of clinical manifestations in this family was particularly interesting. Only two of the children showed any clinical abnormality and this was limited to mild microcephaly and speech delay; the other two children found to excrete large amounts of D(+)-glycerate were healthy and developmentally normal at 7 y and 9 y of age. There was a marked increase in the excretion rate of D(+)-glycerate in response to both oral fructose and serine loading. These results are consistent with a deficiency of D(+)-glycerate kinase and indicate the potentially benign nature of this disorder.

Administration, Oral↗
PubMed1990

Medium-chain acyl-CoA dehydrogenase deficiency: a useful diagnosis five years after death.

We report a family in whom a fatal case of medium-chain acyl-CoA dehydrogenase (MCAD; EC 1.3.99.3) deficiency was diagnosed by enzymatic analysis of heart tissue that had been stored for five years. Three healthy siblings underwent subsequent investigation with the 3-phenylpropionic acid loading test. All siblings had been asymptomatic; however, one (age 2.5 years) excreted large amounts of 3-phenylpropionylglycine in response to the load and exhibited an organic aciduria consistent with the diagnosis of MCAD deficiency. The other two siblings did not demonstrate 3-phenylpropionylglycinuria after the loading test. This case underlines the importance of considering family history and using appropriate diagnostic tests in the recognition of hereditary metabolic disorders.

Acyl-CoA Dehydrogenase↗