Determination of conjugated and unconjugated serum 3 alpha-OH bile acids by high-performance liquid chromatography.

A simple reverse-phase liquid chromatographic method has been developed for the quantitative measurement of 11 3 alpha-OH bile acids in paediatric serum samples. Bile acids are enzymatically reduced to the corresponding 3-keto compound and then derivatized with the fluorophore dansyl hydrazine. Preliminary fractionation of bile acids is not required. The limit of detection is 0.1 mumol/L using a sample size of 200 microL. One hundred and twenty-three serum samples were analysed by the high-performance liquid chromatography (HPLC) method and the results compared with a commercial kit method (Enzabile) presently used in many laboratories for the measurement of total bile acids. There was a good correlation between the two methods (r = 0.96). The method is suitable for use in a clinical laboratory for the further investigation of those patients with abnormally high total bile acid levels where quantification of bile acid fractions is required.

The value of the Mini-Mental State Examination in childhood: a preliminary study.

The Mini-Mental State Examination (MMSE), a screening test of higher mental function, has been modified slightly for use in a pediatric outpatient setting. The test, which takes 5 to 10 minutes to administer, covers a range of cognitive functions including orientation, attention-concentration, memory, language, and constructional ability. In a preliminary study, we have found that the test can be applied from the age of 4 years. Highly significant correlations were found between the MMSE score and chronologic age (r = .57; P < .001), reading age (r = .79; P < .001), and mental age (r = .83; P < .001). MMSE scores reach a plateau at a mental age of approximately 10 years. The MMSE is a suitable instrument for screening higher mental function in children at the age of 4 years and above and can be readily incorporated into the routine neurologic examination of children.

Determination of delta-aminobutyric acid and other amino acids in cerebrospinal fluid of pediatric patients by reversed-phase liquid chromatography.

The reversed-phase liquid-chromatographic system described here is capable of resolving the neurotransmitter amino acids aspartic acid, glutamic acid, and gamma-aminobutyric acid (GABA) plus 21 other amino acids in cerebrospinal fluid (CSF) in a single analysis. The amino acids, derivatized with o-phthalaldehyde, are separated in 65 min. Concentrations of glutamine less than or equal to 600 mumol/L can be measured at the same time as GABA greater than or equal to 10 nmol/L. Using this method, we have determined reference intervals for amino acids, including GABA, in CSF in a group of pediatric patients who underwent lumbar puncture before myelography, and who were subsequently shown to have normal myelograms. These intervals are generally lower than those previously reported for childhood, but we believe this results from a more rigid selection of the control group. In addition, artifactual increases in concentrations of free neurotransmitters, caused by breakdown of amino acid conjugates, are minimized by (a) immediate freezing of the CSF samples to prevent enzyme-mediated changes, (b) omission of a deproteinization step, and (c) precolumn derivatization to reduce on-column breakdown of amide and peptide forms.

Salivary anticonvulsant levels in children: a comparison of methods.

Levels of the anticonvulsant drugs phenobarbitone, phenytoin, carbamazepine, and primidone were measured in the plasma and saliva of 202 epileptic children (5 months-18 years old). Gas-liquid chromatography (GLC) and EMIT immunoassay were used to analyse the samples. Saliva to plasma ratios were as follows (means +/- SD). phenobarbitone: GLC, 0.30 +/- 0.05 (r = 0.94); EMIT, 0.31 +/- 0.06 (r = 0.92); phenytoin: GLC, 0.11 +/- 0.02 (r = 0.94); EMIT, 0.12 +/- 0.04 (r = 0.86); carbamazepine: GLC, 0.26 +/- 0.05 (r = 0.91); EMIT, 0.25 +/- 0.06 (r = 0.83); primidone: GLC, 1.04 +/- 0.24 (r = 0.94); EMIT, 0.95 +/- 0.20 (r = 0.98). There was good agreement between the two methods, and the ratios obtained are the same as those found for adults.