Biomedical subjects
Publications and source records attributed to M Kroeker.
Restrictive dermopathy is an inherited syndrome characterized clinically by severe growth retardation, abnormal skin, characteristic facies, and multiple congenital contractures. Distinctive radiologic features include deficient mineralization of the clavicles and the skull, overtubulation and frequent modeling defects of the long bones, and occasional abnormalities of the ribs and scapulae.
The measurement of cerebral blood flow using the xenon-enhanced computed tomography (XECT) technique requires that the build-up of xenon in both brain tissue and end-tidal expired air be determined as a function of time. Monitoring of the former is carried out using CT scanning and the latter, most often, using a thermoconductivity analyser or mass spectrometer. This paper examines the possibility of greatly simplifying the XECT technique by eliminating the need for either thermoconductivity analyser or mass spectrometer. In the proposed approach, the patient's expired air is channelled through the scan field using a flexible plastic tube and sampled by the CT scanner in conjunction with the build-up of xenon in brain tissue. Phantom measurements have demonstrated the ability of the CT scanner to detect variations in the xenon concentration in expired air while computer simulations have shown that errors arising as a result of the proposed methodology are small compared to other inherent sources in the XECT technique.
Lipophilic maprotiline metabolites were extracted from human urine and animal excreta, with or without prior enzymic hydrolysis, purified by repeated t.l.c. and their structures determined by u.v., n.m.r. and mass spectrometry. Urine from patients under treatment with maprotiline contained the isomeric phenols, 2- and 3-hydroxymaprotiline, the 2,3-dihydrodiol, and an alcoholic metabolite, besides smaller quantities of the corresponding N-demethylated compounds. In dog urine and/or faeces the same products of aromatic hydroxylation were present as in human urine and in addition 3-hydroxy-2-methoxymaprotiline; alcohols were not detected. The only metabolites identified in rabbit urine and rat bile were 3-hydroxy- and 3-hydroxy-2-methoxymaprotiline.
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