Biomedical subjects
Publications and source records attributed to J Obenberger.
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We studied the effect of lysolecithin on the clearing of plasma cholesterol. The immediate and maximal conversion of plasma lecithin to lysolecithin was produced in rats by intravenous injection of phospholipase A. The changes which took place in the converted lysolecithin and of cholesterol were followed in rats which had previously received [32-P]phosphate and [14-C]cholesterol. We followed simultaneously the in vitro changes in blood removed immediately after the in vivo administration of phospholipase A. The experiments showed that a substantial part of the plasma lecithin was converted to lysolecithin within the first minute after intravenous administration of phospholipase A. In the course of 60 min of blood incubation, the ratio of plasmatic lysolecithin in the closed system continued to increase. At the same time the content of cholesterol also increased. In vivo, the converted lysolecithin was quickly released from the plasma, so that within 10 min the original lecithin content dropped to 15-5% depending on the dose of phospholipase A that had been administered. The content of sphingomyelin and lysolecithin, which increased only temporarily shortly after injection, did not alter during the experiment. The level of plasma cholesterol esters, however, dropped significantly, whereas the free cholesterol content increased. The molar ratio of the drop in lipid phosphorus and cholesterol esters in plasma after the administration of phospholipase A was similar. A significantly higher cholesterol content was found in the liver of animals treated with phospholipase A.
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Magnetic resonance imaging is a method of choice for the diagnosis of microprolactinomas. Using a Phillips Gyroscan NT 15 (1.5 T), 42 patients whose clinical history and serum prolactin levels were compatible with the diagnosis of prolactinomas were examined. Four patients (3 male and 1 female) with macroadenoma were investigated and excluded, while microprolactinoma was found in the other 38 (32 female and 6 male) patients. Imaging features were similar in all microprolactinomas--hypointensity up to 10 mm in size in T1 weighted images, only sometimes, in the case of a cystic or a hemorrhagic component, also registered in T2 weighted images. Deviation of the pituitary stalk was present in 19 of the 38 patients (16 with microprolactinoma, 3 without any detectable lesion). Convex upper limit of the gland was demonstrated in 17 subjects (16 microprolactinomas, 1 without detectable lesion). Pituitary adenoma is not the only cause of raised serum prolactin level. This can be a consequence of medication, spinal cord tumor, compression of the pituitary stalk, hypothyroidism or a lesion in dermatomes T3 to T5 (mammary gland level). Results from imaging must always be assessed in the light of the patient's clinical history and biochemical parameters.
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