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Biomedical subjects

M Sheehan

Publications and source records attributed to M Sheehan.

100 records · Page 6Linked to original sources
PubMed1977

Combined thin-layer and gas-liquid chromatographic identification of tricyclic antidepressants in urine.

A combined thin-layer and gas-liquid chromatographic (TLC-GLC) procedure for determination of tricyclic antidepressant drugs in urine is described. GLC on 1.5% OV-17 was utilized to analyzed basic urine extracts directly for the tricyclics and to confirm the identity of spots extracted from thin-layer chromatograms, and TLC was used to confirm the results of these GLC screens. Lower limits of sensitivity for the thin-layer spot extraction procedure were found to range from 2 mug/ml for amitriptyline and imipramine to 10 mug/ml for desipramine and nortriptyline. Turn-around-times for the GLC tricyclic screens were usually less than 1 h. The finding that nortriptyline and desipramine were chemically altered under various extraction conditions was used as a means of confirming the identity of these drugs, and the identity of these chemically altered derivatives was discussed with reference to their low resolution mass spectra.

Adolescent↗
PubMed1977

Gas-chromatographic/mass-spectrometric determination of theophylline in whole blood.

We describe a combined gas-chromatographic mass-spectrometric method for determination of theophylline in whole blood. With use of a probability-based matching approach, the extensive gas-chromatographic interference did not affect mass-spectrometric quantitation of theophylline. Concentrations expected and found were linearly related from 1 to 60 mg/liter; the run-to-run coefficient of variation was less than 8%, within-run less than 6%. Some other xan-thines and drugs frequently co-administered with theophylline did not affect results. Only 0.2 ml of blood is required, which makes the procedure useful for monitoring theophylline in newborns and pediatric populations.

Chromatography, Gas↗
PubMed1976

Rapid gas chromatographic determination of underivatized theophylline in whole blood.

A rapid gas chromatographic method for the determination of underivatized theophylline in whole blood is described. Theophylline is extracted from acidified blood and chromatographed directly using cyheptamide as an internal standard. Concentrations of the drug down to 2 mug/ml in blood could be determined with recoveries ranging from 90 to 110%.

Chemical Phenomena↗
PubMed1975

GLC determination of underivatized carbamazepine in whole blood.

This report describes a rapid GLC assay for carbamazepine in blood. Carbamazepine is chromatographed directly using phenyl methyl silicone gum as the stationary phase. The calibration curve is linear up to 50 mug/ml, with a lower limit of sensitivity of 1 mug/ml. Other anticonvulsants may be measured simultaneously, and the procedure works equally well with plasma or blood.

Carbamazepine↗
PubMedDate not supplied

Langerhans cell histiocytosis of hypothalamus and optic chiasm: CT and MR studies.

The clinical, CT, and magnetic resonance features of two cases of hypothalamic/optic chiasm involvement with Langerhans cell histiocytosis are presented. In both cases, the mass was iso- to hyperdense on noncontrast CT with uniform postcontrast enhancement, whereas with magnetic resonance (one case) the mass remained isointense to brain on both long and short repetition time sequences. The pathophysiology of hypothalamic pituitary dysfunction is briefly reviewed.

Adolescent↗
PubMedDate not supplied

Mortality among drug addicts in Greater London.

During January 1970 to December 1974, 134 deaths in people aged 10-50 years investigated by coroners in Greater London were recorded as being due to drug addiction. Over three-quarters of the addicts were under 30, and 105 (78%) were male; 55 (41%) were unknown to the Home Office. Barbiturate overdose accounted for over half of the deaths, though two-thirds of these were in people registered as addicts to notifiable drugs. Since the Home Office index is concerned with addiction to one class of drugs only, it fails to reflect accurately the prevalence of all serious forms of addiction. Owing to the continuous change in drug-taking behaviour, however, probably no one method of assessment can provide a complete picture, and thus complementary research methods are essential.

Adolescent↗