Consideration on the effects of pollution at community and population level.

The effects of pollution at population level are considered in relation to demographic characteristics and overall to the birthrate. The direct and indirect effects of pollution on community structure is discussed. The influence of pollution may vary according to the food-chain structure; (as a consequence, the hazard 'ceteris paribus' will be greater in freshwater communities than in marine ones). Relations between 'diversity' and 'stability' are discussed. In addition, the advantages and difficulties in using 'diversity' and 'biotic' indices for monitoring polluted water are taken into account.     

Aging alters resynchronization of the circadian system in rats after a shift of the light-dark cycle

Four days following an 8-h advance of the light-dark cycle, the circadian rhythms in the pineal N-acetyltransferase activity and melatonin content reappeared in 7-week-old rats, but were still abolished in 24-month-old animals.     

Leão's spreading depression in the cerebellum of rat

Zusammenfassung Ischämie ruft in der Kleinhirnrinde eine ähnliche Depolarisation hervor wie in der Grosshirnrinde. Durch lokale KCl-Applikation erhält man in der Kleinhirnrinde langsame Potentialwellen, die in Amplitude und Ausbreitungsgeschwindigkeit der «spreading depression» vonLeão in der Grosshirnrinde entsprechen. Ischämie und lokale Applikation von 2,4-Dinitrophenol bewirken in beiden Rindengebieten gleiche Verschiebungen der Kaliumionen.     

Fluorescent staining techniques in Early diagnosis of tissue alterations

Zusammenfassung Lumineszenzmikroskopisch wurde in histologischen Schnitten nachgewicsen, dass nach Nitrofuranverabreichung der Anstieg der Fluoreszenzintensität der Leberzellen im Lebergewebe von Ratten dem Störungsgrad des Zellmetabolismus entsprach. Im Tumorgewebe kranker Tiere lokalisierten sich intensiv fluoreszierende Zellen am Aussenrande von Krebsnestern.     

Kinetics of division in PHA-stimulated pig lymphocytes

Our results indicate that pig lymphocytes in culture complete their 1st division at 24 h. At 36 h there are 9% of cells in 2nd division. 3rd mitosis appears at 48 h; and at 72 h there are cells engaged in the 4th division.