Formation of histamine in transplants from a rat mammary carcinoma

Zusammenfassung Tumorgewebe von Ratten mit subcutan transplantiertem Walker-Milchdrüsencarcinom 256 produzierte¹⁴C-Histamin mit beträchtlicher Geschwindigkeit bei Inkubation des Krebsgewebes mit¹⁴C-Histidin. Zusatz von Pyridoxal-5-phosphat aktivierte die Histidindecarboxylase des Krebsgewebes. In normalem Milchdrüsengewebe lag die Histaminbildung ausserhalb des Messbereichs. Der Histamingehalt des Krebsgewebes war sehr niedrig und Mastzellen wurden keine gefunden. Der Histaminmetabolismus des Carcinoms 256 ist demjenigen im Rattenembryo und im Granulationsgewebe heilender Hautwunden ähnlich.     

Fetal rat brain hemisphere tissue in nonadherent stationary organ culture

Summary A simple organ culture system for brain tissue is described. Fragments of fetal rat brain hemisphere tissue are explanted to multiwell dishes base-coated with semisolid agar. In this system nonadherent organ culture can be performed for at least 50 days. Cell migration, biochemical and morphological differentiation and the formation of a layered architecture seem to mimic some of the phenomena occurring in the developing rat brain in vivo. The fragments may therefore be a useful organ culture model for nervous tissue.     

Dissolved organic carbon trends resulting from changes in atmospheric deposition chemistry

Several hypotheses have been proposed to explain recent, widespread increases in concentrations of dissolved organic carbon (DOC) in the surface waters of glaciated landscapes across eastern North America and northern and central Europe. Some invoke anthropogenic forcing through mechanisms related to climate change, nitrogen deposition or changes in land use, and by implication suggest that current concentrations and fluxes are without precedent. All of these hypotheses imply that DOC levels will continue to rise, with unpredictable consequences for the global carbon cycle. Alternatively, it has been proposed that DOC concentrations are returning toward pre-industrial levels as a result of a gradual decline in the sulphate content of atmospheric deposition. Here we show, through the assessment of time series data from 522 remote lakes and streams in North America and northern Europe, that rising trends in DOC between 1990 and 2004 can be concisely explained by a simple model based solely on changes in deposition chemistry and catchment acid-sensitivity. We demonstrate that DOC concentrations have increased in proportion to the rates at which atmospherically deposited anthropogenic sulphur and sea salt have declined. We conclude that acid deposition to these ecosystems has been partially buffered by changes in organic acidity and that the rise in DOC is integral to recovery from acidification. Over recent decades, deposition-driven increases in organic matter solubility may have increased the export of DOC to the oceans, a potentially important component of regional carbon balances. The increase in DOC concentrations in these regions appears unrelated to other climatic factors.