Metastasis in a benign duodenal stromal tumour.

Gastro-intestinal stromal tumour (GIST) is increasingly recognized as a distinct entity within the group of soft tissue tumours. Mostly, GIST arises from the muscular components of the stromal layer, but the tumour may also originate from the autonomic nerve system, recently designated as gastro-intestinal autonomic nerve tumour (GANT). The majority of GIST is located in the stomach and small intestine; only 4% of GIST is found in the duodenum. Clinical and pathological criteria to differentiate benign from malignant GIST are not well established. Tumour size and mitotic activity are commonly considered as important features, predicting biological behaviour and outcome. It has been suggested that the clinical course of the GANT-type tumours may be more aggressive. We present a case of a radically resected duodenal stromal tumour with benign features, in a young woman, with metastases to the liver and peritoneum occurring 8 years after the initial diagnosis.

Polybrominated biphenyl and diphenylether flame retardants: analysis, toxicity, and environmental occurrence.

Data on two classes of brominated polyaromatic flame retardants are reviewed with emphasis on analytical aspects, occurrence, fate, and toxicity in the environment. Concentrations of brominated fire retardants are quantified as equivalents of commercial mixtures. Because different congeners behave differently in the environment and show large differences in toxicity, future studies would benefit from the availability of analytical standards of individual congeners. The main environmental properties and mechanisms of toxicity of the PBBs and PBDEs are similar to those of the structurally related PCBs and dibenzodioxins. Although the present concentrations of brominated fire retardants do not yet appear to represent a major environmental risk in marine food chains, their replacement by environmentally less harmful alternatives is recommended.

Placental transfer and metabolism of purines and nucleosides in the pregnant guinea pig.

The placental transfer and metabolism of several purines and nucleosides have been investigated using an artificially perfused guinea-pig placenta. A model describing transfer and metabolism in the uteroplacental unit is constructed and applied. Measurements of oxypurines and guanine have been performed in vivo in the blood of pregnant guinea pigs and their fetuses. It appears that only the oxypurines and, to a lesser extent, guanine are present in the maternal and fetal circulations. These purines could be involved in transfer from mother to fetus and used for salvage in the fetal tissues.