Prostaglandin E2 accelerates enzymatic and morphological maturation of the small intestine in suckling rats

The effect of prostaglandin E2 (PGE2) injection on the postnatal maturation of the 16-day-old rodent small intestine was studied. Previous studies have shown that 16,16-dimethyl PGE2 induced several morphological and biochemical parameters in the small intestine of 11-day-old rats. PGE2 was given subcutaneously daily at doses of 2 and 4 mg/kg body weight on postnatal days 11-15. After treatment there was a rise in the mean activities of sucrase, maltase, lactase and aminopeptidase. In rats receiving 4 mg/kg PGE2, sucrase activity was strongly stimulated (p < 0.001) in the proximal and the distal small bowel. In the duodenum, PGE2 treatment (4 mg/kg body weight) produced a significant increase in crypt depth (35%, p < 0.001), although villus height was not modified. Serum corticosterone levels were significantly increased in PGE2-treated rats. The results seem to indicate that PGE2 accelerates enzymatic and morphological intestinal maturation and this effect could be mediated by an increase in corticosterone.

Physicochemical characterization of acetaminophen-ethylcellulose solid dispersion

In this study, ethylcellulose was evaluated as a carrier for the preparation of sustained release of acetaminophen via solid dispersion technique. Physical mixture at the same level of acetaminophen and ethylcellulose was prepared. Differential scanning calorimetry and scanning electron microscope were used to characterize the physical properties of the various systems and to determine if there is possible interaction between acetaminophen and ethylcellulose.

Sustained release phenylpropanolamine hydrochloride from ATO 888 matrix

Sustained release phenylpropanolamine HCl tablets were prepared with compritol as a retardant material. The effects of varying wax levels and methods of matrix formation on drug release were investigated. Also the compaction profiles were recorded for all formulations. The amount of drug in the formula was held constant (10% w/w), while the wax level was varied from 10% to 50% w/w. Two methods were used for the preparation of drug: wax systems; physical mixture and solid dispersion. The drug release from tablets containing 10% Compritol and prepared by solid dispersion was 97% after six hours of testing dissolution. Tablets prepared with 30% wax released 72% of the drug, while tablets containing 50% wax released only 30% of the drug after six hours. Tablets prepared by physical mixture gave higher drug release than tablets prepared by solid dispersion method. The incorporation of Compritol decreased the ejection forces of tablets during compaction. The drug release from tablets prepared by solid dispersion followed the diffusion controlled model described by Higuchi for inert porous matrix.

Ethylcellulose as a carrier for controlled-release acetaminophen tablets

In this study ethylcellulose was evaluated as a carrier for preparation of prolonged release acetaminophen tablets. Solid dispersions containing three levels of ethylcellulose and acetaminophen (1:3; 1:1; 3:1) were prepared by the solvent method. Also physical mixtures at the same level of ethylcellulose and acetaminophen were prepared. Systems composed of solid dispersion or physical mixture containing the equivalent weight of 50 mg acetaminophen, Emcompress as diluent and 1% magnesium stearate as lubricant were compressed into tablets and tested for dissolution. The dissolution data showed that the drug release decreased as the level of ethylcellulose increased in the solid dispersion formulations. The drug release from tablets prepared with solid dispersion followed the diffusion controlled model for inert porous matrix, while the drug release from tablets prepared with physical mixture followed the first-order kinetic model.

Overexpression of Mos, Ras, Src, and Fos inhibits mouse mammary epithelial cell differentiation

Mammary epithelial cells terminally differentiate in response to lactogenic hormones. We present evidence that oncoprotein overexpression is incompatible with this hormone-inducible differentiation and results in striking cellular morphological changes. In mammary epithelial cells in culture, lactogenic hormones (glucocorticoid and prolactin) activated a transfected beta-casein promoter and endogenous beta-casein gene expression. This response to lactogenic hormone treatment was paralleled by a decrease in cellular AP-1 DNA-binding activity. Expression of the mos, ras, or src (but not myc) oncogene blocked the activation of the beta-casein promoter induced by the lactogenic hormones and was associated with the maintenance of high levels of AP-1. Mos expression also increased c-fos and c-jun mRNA levels. Overexpression of Fos and Jun from transiently transfected constructs resulted in a functional inhibition of the glucocorticoid receptor in these mouse mammary epithelial cells. This finding clearly suggests that glucocorticoid receptor inhibition arising from oncogene expression will contribute to the block in hormonally induced mammary epithelial cell differentiation. Expression of Src resulted in the loss of the normal organization and morphological phenotype of mammary epithelial cells in the epithelial/fibroblastic line IM-2. Activation of a conditional c-fos/estrogen receptor gene encoding an estrogen-dependent Fos/estrogen receptor fusion protein also morphologically transformed mammary epithelial cells and inhibited initiation of mammary epithelial differentiation-associated expression of the beta-casein and WDNM 1 genes. In response to estrogen treatment, the cells displayed a high level of AP-1 DNA-binding activity. Our results demonstrate that high cellular AP-1 levels contribute to blocking the ability of mammary epithelial cells in culture to respond to lactogenic hormones. This and other studies indicate that the oncogene products Mos, Ras, and Src exert their effects, at least in part, by stimulating cellular Fos and probably cellular Jun activity.

Granule containing cells in the crayfish third abdominal ganglion

1. Four of the 850 neuron cell bodies of the crayfish third abdominal ganglion contain large dense secretory granules. 2. The processes of these cells form a neurohemal organ in the dorsal perineurium/neurilemma in the ganglion. 3. None of the immunocytochemically identified peptides accounts for the observed distribution of granules.

Relationships between cell size and nuclear morphology in crayfish neurons

The morphology and ultrastructure of cell nuclei in neurons of the third abdominal ganglion of crayfish were studied from alternating series of ultrathin and semithin sections. The ganglion contains approximately 850 neurons with sizes between 10 and 200 microm. Cell nuclei show a great variability. Their size, the chromatin distribution, the number of nuclear pores, the degree of nucleolar segregation and the size of nucleolus vary in close relationships with the cell size.

Unilateral forelimb deafferentation in the monkey: purposive movement

Monkeys with unilateral dorsal rhizotomy C2-T3 used their denervated limbs to retrieve unseen food pellets when movements of the intact contralateral limb were rendered ineffective by enclosure of the hand within a container. Even after protracted use in this condition, however, the deafferented limb ceased to be used in the test situation when the intact arm was released. These findings cast doubt on interpretations of lack of use of a unilaterally dorsal rhizotomized limb as being due to cross-spinal inhibition or to learned disuse.