Investigation of urea cycle enzyme disorders by 1H-NMR spectroscopy.

High resolution proton nuclear magnetic resonance spectroscopy (1H-NMR) has been used to study patients with inborn errors of the urea cycle to evaluate further the diagnostic potential of this technique. The 1H-NMR metabolic profile from the urine of patients with citrullinaemia and argininosuccinic aciduria consistently demonstrated the presence of the diagnostic metabolites citrulline, N-acetylcitrulline and argininosuccinate, respectively. The profile from the urine of patients with ornithine carbamoyl transferase deficiency, is potentially diagnostic, but orotate was only detected in samples from three out of four patients. The characteristic fingerprint that each of the metabolites produces is unlike that of any other we have seen, including analogues of the metabolites which are structurally very similar such as arginine, ornithine and aspartate. The level of excretion of the metabolites from the patients with citrullinaemia and argininosuccinic aciduria has been well within the range of NMR detection.

Arbitration in one easy lesson: a review of criteria used in arbitration awards.

Some managers find awards of arbitrators "arbitrary, capricious, and discriminatory", Donald A. Woolf believes, however, that a knowledge of decisional criteria used by arbitrators can help managers to understand how they reason. Among the criteria discussed are the de minimus rule, the major/minor test, promissory estoppel, parol evidence, contract language, past practice, "clean hands", and the punishment fitting the crime (equity). Such knowledge can also help managers avoid actions that are likely to lead to grievances in addition to planning a course of action to avoid grievances going to arbitration in the future.

Blood lead levels in Omani children admitted to hospital.

Whole blood lead levels were estimated by atomic absorption analysis in 119 Omani children admitted to hospital. Eighteen per cent of the children were found to have a blood lead level of 1.2 mumol/l or more, 5 per cent were found to have a level above 2.4 mumol/l and 3 per cent had very high levels in excess of 3.4 mumol/l. No overall relationship was demonstrated between age and blood lead levels. However, children less than 3 years old were three times more likely than those 3 years or above to have a blood lead level in excess of 2.4 mumol/l. The results of this study are sufficiently worrying to justify a more widespread community based survey of blood lead levels in Omani children.

Aetiology of acute lead encephalopathy in Omani infants.

Twenty-five Omani infants were admitted with acute lead encephalopathy. They ranged in age from 1 to 8 months with the majority less than 4 months old. The source of poisoning in 20 infants (80 per cent) proved to be a local medication called bint al dahab. In a further three infants (12 per cent) there was a strong recent history of administration of a local medication, but the agent could not be identified with certainty. As with older children acute lead encephalopathy has serious consequences and in this series only 44 per cent of infants were thought to be neurologically normal at the time of discharge. The administration of lead containing medications to young infants in Oman is a significant preventable cause of morbidity and mortality having implications, in particular, for physicians involved in the care of Arabic communities. In any infant presenting with an unexplained encephalopathy the diagnosis of lead poisoning should be considered.

Indirect measurements of sweat electrolyte concentration in the laboratory diagnosis of cystic fibrosis.

AIM: To investigate whether analytical methods based on the colligative physical chemical properties of ions or solutes in sweat are less effective than the specific measurement of electrolytes in the diagnosis of cystic fibrosis (CF). METHODS: A single sweat sample was collected (Macroduct) from each of 211 infants and children, of whom 57 had CF, for the measurement of sodium, chloride, osmolality, and conductivity. RESULTS: The ranges within which CF and non-CF individual values overlapped (equivocal ranges), were wider for sodium and osmolality measurement than for chloride or conductivity. Neither of the latter two measurements provided a discriminatory advantage over the other. The utilisation of broadly based age related ranges for non-CF control subjects served to improve the discriminatory power of all four measurements to an extent that, in this cohort, both chloride and conductivity provided complete discrimination. CONCLUSION: Sweat conductivity is as effective as chloride measurement in the laboratory diagnosis of CF.

Rapid diagnosis of medium-chain acyl CoA dehydrogenase deficiency by measurement of cis-4-decenoic acid in plasma.

Plasma concentrations of octanoate and cis-4-decenoate were measured by gas chromatography-mass spectrometry in children with deficiencies of medium-chain acyl-CoA dehydrogenase (MCAD), long-chain 3-hydroxyacyl-CoA dehydrogenase (3LHAD) and multiple acyl-CoA dehydrogenase (MAD) deficiency. Children receiving medium- and long-chain lipid supplements were also studied. Octanoate was elevated in all but one of the children with MCAD deficiency, in MAD deficiency and in children receiving medium-chain triglyceride supplementation. Cis-4-decenoate was only elevated in MCAD and MAD deficiency. It is concluded that measurement of plasma cis-4-decenoate provides a sensitive and specific test for defects of medium-chain acyl CoA dehydrogenase.

Lead lines in young infants with acute lead encephalopathy: a reliable diagnostic test.

Fifteen Omani infants, ranging between 2 and 4 months of age, with acute lead encephalopathy underwent plain skeletal radiology. X-rays in all 15 infants revealed dense metaphyseal bands in long bones. These were best seen around the knee joint. Six infants had evidence of multiple lead lines indicating previous episodes of exposure to lead while four infants also had lead lines in the axial skeleton. We suggest that any young infant presenting with an unexplained encephalopathy should undergo an X-ray of the knee and that the presence of dense metaphyseal bands strongly supports the diagnosis of lead poisoning. A plain X-ray of the knee is a cheap, widely available investigation which can be rapidly obtained.

A randomised crossover trial of facemask efficacy.

The efficacy of different facemasks that can be used in the delivery of aerosol medication to children with recurrent wheeze or asthma was investigated. The results showed a statistically significant difference between some of the masks used, which has important implications for current clinical practice

Nesidioblastosis: evidence for autosomal recessive inheritance.

The risk of recurrence of nesidioblastosis is unclear. Thirty patients from 28 families were studied; the marriages were consanguineous in five families. The ratio of subsequent affected to unaffected siblings was similar to that of an autosomal recessive condition and the sex ratio was close to 1.

Effect of treatment with glycine and L-carnitine in medium-chain acyl-coenzyme A dehydrogenase deficiency.

To assess the relative contribution of glycine and carnitine conjugation pathways to total acyl-group excretion, we investigated the excretion of C6 to C10 dicarboxylic acids, C6 to C8 acylglycines, and C6 to C8 acylcarnitines in five symptom-free patients with medium-chain acyl-coenzyme A dehydrogenase deficiency during sequential 1-week periods as follows: (1) no treatment, (2) oral supplementation with glycine, 250 mg/kg per day, (3) oral supplementation with L-carnitine, 100 mg/kg per day, and (4) oral supplementation with both combined. In untreated patients, acylglycines and acylcarnitines represented 60% and less than 1% of the total metabolite excretion, respectively; the average acylglycine/acylcarnitine ratio was 70:1. Oral supplementation with glycine did not alter the excretion of acylglycines or acylcarnitines. L-Carnitine supplementation increased the acylcarnitine excretion sixfold and caused a 60% reduction in acylglycine excretion (p < 0.001); however, even with carnitine supplementation, acylglycine excretion was still 10 times greater than that of acylcarnitines. The results suggest that glycine conjugation was the major pathway for the disposal of C6 to C8 acyl moieties and that oral L-carnitine supplements may inhibit glycine conjugation. The findings cast doubt on the value of long-term treatment of medium-chain acyl-coenzyme A dehydrogenase deficiency with L-carnitine.