Hormonal Correlates of Exploratory and Play-Soliciting Behavior in Domestic Dogs.

Exploration and play are considered to be crucial behaviors during mammalian development. Even though the relationship between glucocorticoids and exploratory behavior, stress, and anxiety is well described in the literature, very little is known about their role in play behavior in non-rodents. Likewise, the functional role of the "social hormone" oxytocin in exploration, play, stress, and anxiety is still unknown.

A galactose-specific lectin from the red marine alga Ptilota filicina.

A lectin from the red marine alga Ptilota filicina (PFL) was isolated by affinity chromatography on cross-linked guar gum. PFL agglutinated native and papain-treated human erythrocytes with preference for type O erythrocytes. The lectin was inhibited by galactose and its derivatives.

Some kinetic properties of guinea pig liver monoamine oxidase.

Titration of monoamine oxidase activity in isolated guinea pig liver mitochondria with clorgyline and assay of remaining activity with tyramine yielded biphasic inhibition curves. The position of the plateaus obtained with mitochondria from four animals, indicated that the B form of monoamine oxidase accounted for 30% to 70% of the tyramine deaminating activity. Benzylamine deamination was selectively inhibited by (-)-deprenyl.

Some problems associated with measuring monoamine oxidase activity in the presence of sodium azide.

The colourimetric assay of monoamine oxidase activity, as hydrogen peroxide production, normally requires the use of sodium azide to inhibit breakdown of hydrogen peroxide by catalase. Sodium azide was shown to act as an uncompetitive inhibitor of benzylamine deamination with an inhibitor constant of 1.5 mM.

Deamination of hordenine by monoamine oxidase and its action on vasa deferentia of the rat.

The selectivity of the naturally occurring amine, N,N-dimethyltyramine (hordenine) for monoamine oxidase (MAO) and its action upon isolated vasa deferentia of the rat was investigated. Hordenine was deaminated by rat liver MAO with a Michaelis constant of 479 microM and maximum velocity of 128 nmol (mg protein)-1 h-1 compared with 144 microM and 482 nmol (mg protein)-1 h-1 for tyramine. Studies, with selective irreversible inhibitors of MAO, showed that hordenine was a highly selective substrate for MAO-B of liver and that it was not deaminated by the MAO-A of intestinal epithelium.