Absorption of intragastrically administered DDAVP in conscious dogs

Plasma concentrations of DDAVP were measured after intragastric administration and intravenous infusion in dogs. Oral ingestion of DDAVP led to a dose dependent increase in peak plasma concentrations as well as area under the curve (AUC). Intravenous infusion of DDAVP (0.13 pmol/l min) resulted in a mean steady-state level of 20.3 pmol/l. Elimination half-lives for oral DDAVP were 77.6 and 76.1 min for low and high doses respectively. T1/2 estimated from the ascending part of the i.v. infusion curve was 50 min. A metabolic clearance rate (MCR) of 3.9 ml/kg . min was assessed from the i.v. steady-state level.     

Disorganization of stroma alters epithelial differentiation of the glandular stomach in adult mice

Summary The response of adult epithelium in contact with heterologous mesenchymes/stromas was studied in three digestive organs (forestomach, glandular stomach, and duodenum). After various tissues were implanted beneath the epithelial layer of adult mice, the epithelial differentiation was examined after sacrifice of animals at intervals up to 24 weeks. In the forestomach and duodenum, the epithelial differentiation was not affected at all by the tissue implantation. In the glandular stomach, in contrast, epithelial cells exhibited altered differentiation in which chief and parietal cells disappeared and were replaced by columnar epithelial cells with PAS-positive granules. These epithelial cells often formed immature villi. Such differentiation-altered columnar epithelium (DACE) was induced by implanting any type of tissue and even by sham operation, indicating that it was induced by disorganization of the tissue-implanted stroma. The size of DACE was significantly influenced by the stage of implanted tissue; 14.5-day fetal mesenchyme induced the largest DACE, and was followed by 16.5-day fetal mesenchyme, adult stroma, and sham operation. These results suggest the importance of stromal organization in maintaining epithelial differentiation in the glandular stomach.     

The effect of acutely administered beta-casomorphin derivatives on pentylenetetrazol-kindled mice

Some of the Tyr-containing and desTyr beta-casomorphin derivatives were tested for their anticonvulsant action in pentylenetatrazol-kindled mice. It was demonstrated that some of these substances exert powerful action against kindled seizures, suggesting therapeutical usefulness.     

Histochemical characteristics of the epitheliocytes of the avian glandular stomach

A complex histochemical investigation has been undertaken to study the epithelial lining of the glandular stomach in birds having various types of nutrition. The protective barrier of the avian stomach has been found to be characterized as a resistant (mucosal) barrier, with neutral glycoproteins, sialo- and sulphoglycoproteins as its components. Differences in histochemical properties of the epitheliocyte secretion have been described in birds with different types of nutrition. They are connected with various correlation of carbohydrates and proteins in the composition of the micromolecular glycoprotein complex. The data obtained are compared with those concerning the histochemical properties of the stomach in amphibia and reptiles which have the mucous membrane structure similar to that in the avian stomach.     

Differential effect of colchicine upon the entry of proteins into myelin and myelin related membranes

Brain slices from 20 day old rats were incubated with radioactive aminoacids in the presence and absence of 500 M colchicine and the appearance of labeled proteins in myelin and in a myelin-like fraction (SN₄ fraction) was measured. In the presence of the inhibitor, the entry of proteolipid proteins was decreased to 55% in myelin and to 45% in SN₄ fraction with reference to control values while the entry of basic proteins and other minor protein components was unaffected in both fractions. The synthesis of proteolipid proteins was not affected by the presence of colchicine; moreover, a slight accumulation of these proteins was observed in microsomes. The results suggest that the microtubular system is involved in the transport of proteolipid proteins from their site of synthesis to their site of deposition and that the various types of myelin proteins follow different transport routes to enter into this special type of membrane.     

Intracellular enzyme localization in the epithelium of the bovine glandular stomach

The intracellular localization of calcium adenosine triphosphatase (Ca2(+)-ATPase) was studied ultracytochemically in the pyloric glands of the abomasal mucosa of cattle. A remarkable staining pattern exhibited the Golgi apparatus, as there was a gradation in staining of the interior sides of dictyosomal cisternae from the not or weakly stained cis to the heavily stained trans face. Membranes of Golgi-endoplasmic reticulum lysosome complex-secretory vesicles showed either no or strong enzyme activity. Membranes of secretory vesicles accumulated in the cell apex stained positive for ATPase activity. This accounts also for the apical cortical cytoplasm. From these results it is speculated that Ca2(+)-ATPase may play an important role in the pathway of exocytotic secretion, especially in the process of membrane sorting and biogenesis of secretory vesicles, in the steps of vesicle accumulation and transport to the site of exocytosis as well as in membrane fusion events.     

Detection of micronucleated cells and gene expression changes in glandular stomach of mice treated with stomach-targeted carcinogens

To assess the genotoxicity of chemicals on the stomach, we developed in vivo assays that can detect micronucleus induction and gene expression changes in epithelial cells of the glandular stomach in mice. Male BALB/c mice were orally given a single dose (100 mg/kg) of N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as stomach-targeted carcinogens. The glandular stomach was excised at 4h, 3 and 4 days after administration, and a single cell suspension of epithelial cells was prepared from the everted glandular stomach by EDTA treatment. For determination of micronucleus induction, gastric epithelial cells on days 3 and 4 after administration were fixed with 10% neutral-buffered formalin, stained with a combination of AO-DAPI, and analyzed under fluorescence microscopy. We also examined the induction of micronuclei in peripheral blood of these mice on days 2 and 3 after administration. Moreover, total RNA was extracted from gastric epithelial cells at 4h after administration, and p21 and plk2 expression was analyzed using a quantitative RT-PCR technique. 1) A significant increase of micronucleated cells was observed in the glandular stomach in mice treated with N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) compared to mice treated with vehicle. 2) In peripheral blood, induction of micronuclei was observed in mice treated with MNU but not with MNNG. 3) p21 and plk2, which related to cell cycle arrest, were up-regulated in the glandular stomach in mice treated with MNU or MNNG compared to mice treated with vehicle. The present study showed that these assays using glandular stomach may help to evaluate the genotoxicity of chemicals after oral administration.     

Angiogenic effect of colchicine

The effect of colchicine on the microcirculatory vessels of eye perilimbal area was revealed in 2 groups of experimental rabbits. Colchicine was found to promote the growth of capillaries both during intravenous injections of colchicine solution and during local colchicine application as an ointment. The proper substance of cornea was also changed under the influence of colchicine. Changes in the ultrastructure of the capillary wall and endothelial cells forming the capillaries have been noted.     

The role of chloride ions in histamine-induced electric reactions of the glandular cells of the stomach

The effect of Cl- ions on electrical response of gastric gland cells to histamine was investigated using intracellular glass microelectrodes. It was established that in chloride-free solution and in solution with a blocker of chloride transport the hyperprolarization evoked by histamine after 15-20 min decreased and then it was not observed. It is suggested that the chloride ions are necessary for hyperpolarization response of gastric gland cells to histamine actions.     

The role of vitamin A in the formation of extracellular structures of the chicken glandular stomach

Main notions on the vitamin A function in the organism are considered. A new concept is formulated postulating the vitamin A role in the support of the structure and function of the Golgi complex of epithelial cells of glandular stomach mucosa of chickens.     

The effect of colchicine on the sleeve element of microtubules

The microtubules in the nutritive tubes of telotrophic insect ovaries, like those in many other situations, are surrounded by an electron clear zone or ‘sleeve’ after conventional preparative procedures for electron microscopy. Ribosomes, which also pack the nutritive tubes, do not encroach into this region, and although microtubules are often closely opposed, they are rarely seen to touch. The composition of the microtubule sleeve zone is unknown. This study shows that colchicine not only destroys the microtubules in the nutritive tubes, but also the sleeve zone which surrounds them, suggesting that the integrity of the microtubules is essential for the existence of the sleeves.