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Biomedical subjects

B Wilcken

Publications and source records attributed to B Wilcken.

15 recordsLinked to original sources

Genetic screening of the newborn in Australia. Results for 1978.

Since screening of newborn infants for phenylketonuria (PKU) by Guthrie bacterial inhibition assay was established in the 1960s. 2 334 679 infants have been tested in Australia, and 208 cases of PKU detected (an incidence of 1/11 224). In 1978, 21 infants with PKU were detected. Screening for hypothyroidism was carried out in three States, and 29 cases of congenital hypothyroidism were detected in 1978 (an incidence of 1/5894).

Australia

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

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

Prevalence of unsuspected urinary bacterial contamination: effects of screening tests for detection of inborn errors of metabolism.

Hospitals and doctors submitting urine samples to a central reference laboratory screening for inborn errors of metabolism had been given precise instructions on sample handling designed to prevent growth of contaminating bacteria. 140 consecutive samples were examined bacteriologically and 22% had a heavy growth of bacteria (greater than 10(5) organisms/ml). Contamination was commonest in samples from children under 2 years. Normal human urine samples spiked with various amino acids were inoculated with pure cultures of different urinary pathogens and then incubated, with control samples, at 37 degrees C. Urinary amino acids were measured either semi-quantitatively by high-voltage electrophoresis or quantitatively by ion-exchange chromatography. Very wide-ranging changes in amino acid levels were noted in some inoculated samples after incubation. In two urine samples spiked with 8 mg/ml arginine, this had disappeared after 24-48 h. Unsuspected urinary bacterial contamination may be a more important source of false positive and false negative results in the investigation of disorders of amino-acid metabolism than previously supposed.

Amino Acid Metabolism, Inborn Errors

Homocystinuria in New South Wales.

Homocystinuria was studied in 27 patients from 15 families in New South Wales. All 2 had biochemical findings consistent with cystathionine synthetase deficiency. One patient was ascertained by newborn screening, but the remaining index cases were detected because of symptoms: poor eyesight 6, mental retardation 3, thromboses 2, skeletal abnormalities 2, and urinary infection1. 9 patients, one-third of all cases, were mildly affected: either they had no features of the disease, or these did not occur until the late teens. Pyridoxine responsiveness was found in 8 sibships, and clinically there were two distinct kinds of response. For patients born in the decade 1960-69 the ascertainment rate for the total population was 1:58 000. The true incidence must be much higher. Our series indicates that homocystinuria occurs more frequently than has heretofore been thought, and that mild cases are common. It is likely that cases are often missed in current newborn screening programmes.

Adolescent

Methylmalonic aciduria: a variant form of methylmalonyl coenzyme A apomutase deficiency.

Sisters aged 3 and 4 1/2 years, respectively, who had grown and developed normally were found to have methylmalonic aciduria. The elder had had only one previous illness, at 18 months, and was thriving at six years without treatment; she was excreting up to 2 gm methylmalonic acid per day. The younger sister died during her third episode of illness, at 3 years of age. Studies of cultured skin fibroblasts showed deficient methylmalonyl coenzyme A mutase apoenzyme activity; cobalamin metabolism was normal. There was a moderate response in cultured cells to large amounts of added hydroxycobalamin; but treatment of the patient with high doses of intramuscular vitamin B12 for ten days failed to lower the urinary excretion of methylmalonic acid.

Apoenzymes

Natural history of Hartnup disease.

Hartnup disease was diagnosed in 12 children and 3 of their 15 sibs in the course of routine urine screening of 6-week-old infants in New South Wales. These children were followed for up to 8 years, during which time there were only two clinical episodes which might be ascribed to Hartnup disease. The mental development of all the children was normal. 10 had height centiles less than the midparent height centiles, while 4 had centiles equal to or above the midparent centiles. The study shows that in children with Hartnup disease in Australia symptoms are very uncommon. Mental development is normal, and heights are possibly slightly below that expected. Hartnup disease has an incidence of approximately 1 in 33 000 in New South Wales.

Australia

The pathogenesis of coronary artery disease. A possible role for methionine metabolism.

Homocystinuria, an abnormality of methionine metabolism is associated with severe vascular disease in infancy and childhood. Homocysteine is formed during the metabolism of methionine and accumulations of this and of cysteine-homocysteine mixed disulfide in the plasma indicate a partial block in the methionine degradation pathway. Methionine metabolism was investigated in 25 patients aged under 50 with angiographically proved coronary artery disease and in 22 control patients, of whom 17 had normal coronary arteries at angiography and 5 were healthy volunteers. After an overnight fast, venous blood was drawn before and 4 h after oral L-methionine, 100 mg/kg. Plasma methionine levels at 4 h were not different in the two groups, but there were significant differences in the levels of cysteine-homocysteine mixed disulfide. This was detected in 5 of 22 in the noncoronary group and in higher concentration in 17 of 25 coronary patients (P less than 0-01). Age, weight, height, body-mass index, glucose tolerance, fasting serum urate, and triglycerides were not different, but serum cholesterol was higher in the coronary patients (P lessthan 0.01). These results suggest a reduced ability to metabolise homocysteine in some patients with premature coronary artery disease when this pathway is stressed.

Coronary Disease