Selective decrease of duodenal phosphoprotein phosphatase activity is a general property of duodenal ulcerogens.

A phosphoprotein phosphatase (PPPase) is inhibited in rat duodenal mucosal cells very early after a single s. c. injection of the duodenal ulcerogens cysteamine, propionitrile and mepirizole.

The influence of cysteamine and propionitrile on duodenal phosphoprotein phosphatase in rats.

Cysteamine and propionitrile cause severe duodenal ulcers with perforation within 24-48 h after a single injection in rats. These animal models were used to gain insight into the early, preulcerogenic biochemical changes in the duodenal mucosa. The results indicate that a single sc injection of cysteamine and propionitrile induced dose- and time-dependent decreases in the activity of phosphoprotein phosphatase (PPPase) in homogenate and particulate fractions of rat duodenal mucosa.

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. II. Further characterization of E2 casein phosphatase.

Of three casein phosphatases isolated from the cytosol of human cord blood erythrocytes two were cobalt-dependent, E2 and E3. In the presence of CoCl2, E2 activity was the most prominent. In addition to casein, E2 dephosphorylated phosvitin and p-nitrophenyl phosphate (p-NPP) with pH optima at 6.

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. I. Submolecular structure and regulation of activity of E3 casein phosphatase.

We have identified three phosphoprotein phosphatases in the cytosol of human cord blood erythrocytes by sequential anion-exchange chromatography and gel filtration. The most abundant was E3 protein phosphatase. After rechromatography on a column of Ultrogel AcA-44 the enzyme had a molecular weight of 95,000 daltons.

Ontogenetic changes in protein dephosphorylating activity of the cytosolic compartment of rat erythrocytes.

Total casein phosphatase activity of erythrocytes from one-month-old rats was separated by DEAE-cellulose chromatography into three peaks--E1, E2 and E3--and only into two peaks--E1 and E3--when the erythrocyte donors were six- and 12-month-old rats. The activity of E1 (Mr 330 K) decreased continuously in erythrocytes during the first year of postnatal life. E2 (Mr 230 K) also decreased and completely disappeared from the cells of 12-month-old rats.

Chromatographic resolution and characterization of different casein phosphatase activities from the cytosolic compartment of rat erythrocytes.

Casein phosphatase activity in the cytosol of erythrocytes, taken from 1-month-old rats, is associated with three chromatographically distinct peaks: E1, E2 and E3. The dominant molecular form was E3 phosphatase, molecular weight 180,000 dalton, which increased in the cytosol of erythrocytes as compared to the value found in the same compartments of reticulocytes. The enzyme had the pH optimum at 6.

The ontogenetic evolution of acidic phosphoprotein phosphatase activity in the lymphatic tissue and the liver of the rat.

We have shown that an acidic phosphoprotein phosphatase (APP-ase) has a different pattern of postnatal maturation in the spleen, thymus and liver of rats and mice. The APP-ase activity increases during the first eight months of postnatal life in the spleen of rats (when it attains an 8--10 times higher value than at birth) and up to the sixth month of life in the spleen of mice. It increases considerably during the first two weeks of postnatal life in the thymus of rats and mice; in the liver of rats it reaches maximum activity before birth, but continues to increase up to the sixth month of postnatal life in the liver of mice.

Ehanced biliary thyroxine excretion in rats treated with pregnenolone-16alpha-carbonitrile.

Normal rats were treated with pregnenolone- 16alpha - carbonitrile (PCN) 10 mg/100 g by stomach tube twice daily for 3 days. In these animals the biliary excretion of intravenously injected 125I-thyroxine (T4) was enhanced and the bile: plasma 125I ratio (B/P ratio) and the biliary clearance rate of plasma 125I-T4 was increased. Normal rats were treated with PCN for 3 days and homozygous Gunn rats for 13 days.

[Thyroid pigments in Gunn rats].

The structural and histochemical characteristics of the thyroid pigment in homozygous Gunn rats were examined. The pigment occurs in the form of numerous yellow granules in the cytoplasm of the follicular cells. The focal depositions of the pigment were also seen in the central part of the luminal colloid.

[Effect of pregnenolone-16 alpha-carbonitrile on the activity of the rat thyroid gland and anterior pituitary].

PCN, in daily doses of 20 mg/100 g per body weight exerted a marked stimulative effect on the rat thyroid. It was also found that the uptake of radioiodine in animals receiving PCN, was increased. Chromatographic investigations have shown that in PCN treated animals the biosynthesis of thyroid hormones was accelerated.