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Biomedical subjects

R J Truscott

Publications and source records attributed to R J Truscott.

87 records · Page 5Linked to original sources
PubMed1980

Antenatal diagnosis of glutaric acidemia.

Two pregnancies at risk for glutaric acidemia were monitored. In one, in which the fetus was not affected, glutaric acid was not detected in the amniotic fluid at amniocentesis (15 weeks) and the glutaryl-CoA dehydrogenase activity of cultured amniotic cells was normal. In the other, a marked elevation of glutaric acid in the amniotic fluid, together with deficiency of glutaryl-CoA dehydrogenase in amniotic cells, prompted termination of the pregnancy, and studies on the abortus confirmed the diagnosis of glutaric acidemia. Glutaric acidemia, is, thus, another inborn error of metabolism which can be diagnosed in utero.

Acyl Coenzyme A↗
PubMed1979

Studies on a child suspected of having a dficiency in 3-hydroxy-3-methylglutaryl-Co A lyase.

The urine of a child who presented with hyperammonemia was found to contain elevated levels of 3-hydroxy-3-methylglutaric acid, 3-methylglutaconic acid and 3-methylglutaric acid. An increased excretion of these organic acids has been reported previously in a child with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency. Enzyme studies using cultured fibroblasts from this patient, however, indicated that the 3-hydroxy-3-methylglutaryl-CoA lyase activity was not markedly reduced.

Acyl Coenzyme A↗
PubMed1979

Dicarboxylic aciduria: the response to fasting.

The urine of a child who presented with an episode of a disease resembling Reye's syndrome was found to contain large quantities of the dicarboxylic acids adipic and suberic acids, as well as the glycine conjugate of suberic acid, suberyl glycine. A variety of other dicarboxylic acids, both saturated and unsaturated, were also found in the urine at the time of the attack. It was found that the excretion of these unusual metabolites could be markedly increased by fasting for periods of greater than 10 h. These results indicate that the patient may have a defect in fatty acid oxidation which becomes clinically significant during periods of prolonged fasting.

Adipates↗
PubMed1979

The identification of 3-keto-2-methylvaleric acid and 3-hydroxy-2-methylvaleric acid in a patient with propionic acidemia.

Two abnormal metabolites, 3-keto-2-methylvaleric acid and 3-hydroxy-2-methylvaleric acid, have been identified and quantitated in the urine of a child with propionic acidemia. These metabolites may be produced as a result of the self-condensation of propionyl-CoA. Data are presented to show that the unusual ketone, 3-pentanone, which has been observed previously in the urine of patients with propionic acidemia, is produced as a result of the decarboxylation of 3-keto-2-methylvaleric acid.

Gas Chromatography-Mass Spectrometry↗
PubMed1979

Abnormal deoxyribose metabolites in the urine of a child with a possible new inborn error of metabolism.

The urinary extract of a child investigated because of strabismus was found to contain large amounts of a compound which was identified using gas chromatography/mass spectrometry as 2-deoxyerythropentono-1,4-lactone. This lactone has not been observed previously in urinary extracts. When ion-exchange chromatography was used to isolate the organic acids from urine, the major peaks obtained by gas chromatography were shown to be 2-deoxyerythropentonic acid, 2-deoxyerythropentono-1,5-lactone and 2-deoxyerythropentono-1,4,lactone. Another abnormal metabolite, 2-deoxyribitol, was also excreted by the patient although this compound could not be detected in the urine of normal children. It is proposed that these unusual compounds accumulate in the urine of this child as a result of a defect in the catabolism of 2-deoxyribose.

Deoxyribose↗
PubMed1978

Simultaneous determination of diphenylhydantoin, mephobarbital, carbamazepine, phenobarbital and primidone in serum using direct chemical ionization mass spectrometry.

A quantitative method for the simultaneous determination of five anticonvulsants in serum has been developed using chemical ionization mass spectrometry without prior chromatographic separation. The technique was shown to be rapid, simple and sensitive, allowing the routine analysis of 50 microliter of serum with good within-day and day-to-day precision.

Anticonvulsants↗
PubMed1977

Oxidative changes in human lens proteins during senile nuclear cataract formation.

1. Proteins from the cortex and nucleus of the human lens were studied to determine if any changes could be detected in their amino acids during senile cataract formation. 2. Senile nuclear cataract formation was found to be accompanied by a progressive oxidation of cysteine and methionine. The oxidation of methionine and changes in the distribution of the nuclear proteins did not appear to start until about 60% of the cysteine had been oxidized. 3. In the advanced nuclear cataractous lens, about 90% of the cysteine has been oxidized and 45% of the methionine is present as the sulphoxide in the nuclear proteins. The levels of other amino acids appeared to remain constant. 4. Similar, but smaller, changes were found in the cortical proteins in advanced nuclear cataractous lenses, suggesting that the oxidation spreads from the nucleus to the cortex. 5. These changes were discussed with regard to current views on cataract formation and it was concluded that they are probably the result of simple oxidation of the proteins with O2 or H2O2.

Adult↗
PubMedDate not supplied

Evidence for the participation of alpha B-crystallin in human age-related nuclear cataract.

The aim of this study was to determine if the unusual coloured species characteristic of age-related nuclear cataract could be localised to specific residues of the crystallins. The insoluble, crosslinked and coloured cataract protein fraction (CPF) was isolated from cataract human lenses. Using a combination of tryptic digestion, gel filtration and multiple reversed phase high performance liquid chromatography (RP-HPLC), coloured peaks were isolated and subjected to amino acid sequence analysis. With these techniques, it was hoped to identify and locate the modified residues. Sequence information was obtained on 16 'coloured' peptides. Many of the peptides were found to be derived from alpha B-crystallin. When redundancies are taken into account, six distinctive peptides were found to be derived from alpha B-crystallin; one from beta B1-crystallin, two from beta A3/A1-crystallin and three from gamma S-crystallin. Three sites of possible crystallin residue isomerisation to modification were detected in the alpha B- and beta A3/beta A1-crystallins, including probable asp isomerisation at residues 25 and 36 in alpha B-crystallin. Since the CPF is unique to nuclear cataract lenses, these data suggest that alpha-crystallin, and alpha B-crystallin in particular, may be implicated in the cataract process. This finding supports that of a recent study on cataract proteins using pronase digestion [Chen YC, Reid GE, Simpson RJ, Truscott RJW. Exp Eye Res 1997;65:835.]

Aging↗
PubMedDate not supplied

Rapid characterization of chemically-modified proteins by electrospray mass spectrometry.

Electrospray mass spectrometry (ESI-MS) has been used to examine monoclonal antibodies (MAbs), antibody fragments (Fab and Fc), modified fragments, and a range of other chemically-modified proteins as part of a study aimed at establishing ESI-MS as a method for the characterization of radioimmunoconjugates. This has been approached from two angles. Firstly, ESI-MS of complexes formed between chelators and other small molecules conjugated to hen egg white lysozyme (HEL) (14 kDa) demonstrate the considerable advantages of this powerful new technique compared with existing methods for the characterization of chemically-conjugated proteins. Molecular weights can be determined rapidly to within 0.01-0.05% and with good sensitivity (10-50 pmol total), thus providing specific structural information and opening the way for ESI-MS to be applied widely for the structural characterization of radioimmunoconjugates. Secondly, the conditions for ESI-MS of intact antibodies and antibody fragments have been examined in detail, and we have shown that the addition of up to 10 biotin molecules to the 50 kDa Fab fragment can be easily detected in ESI mass spectra, thus demonstrating the potential for the characterization of modified MAb fragments and metabolites. Finally, the strengths and limitations of ESI-MS of intact antibodies are discussed, and these results indicate that it may only be possible to detect average shifts in the mass of intact antibodies following modification.

Animals↗
PubMedDate not supplied

Age-related nuclear cataract: a lens transport problem.

Age-related nuclear cataract is a major cause of blindness. It is characterised by opacification and colouration in the centre of the lens and is accompanied by extensive protein oxidation. The reason for the onset of nuclear cataract is not known, but it is proposed here that the underlying cause is the development, with age, of a barrier to the transport of metabolites within the lens. Such a barrier may result in an increase in the half-lives of reactive molecules, such as UV filters, thus promoting posttranslational modification of proteins in the nucleus and may also act to prevent an adequate flux of antioxidants from reaching the lens interior and, as a consequence, allow oxidation of nuclear components. Further, this oxidation may take place even if the lens outer cortex and epithelium remain perfectly functional.

Aging↗