Epithelial cell types of the primary ureter of Helix aspersa: Ultrastructural and cytochemical characteristics

The present study describes the morphological characteristics which determine the structural polarity of the principal and ciliated cells in the primary ureter epithelium of Helix aspersa. These characteristics are analysed on the basis of the function performed by both cell types. The presence of paniculate glycogen and the location of glycoconjugates associated with cell membranes of the epithelial cells is revealed by the method of Thiéry.     

Light and electron microscopical localization of concanavalin A lectin binding sites in rat epiphyseal chondrocytes

Summary Concanavalin A lectin binding sites have been detected within the cytoplasm of epiphyseal chondrocytes. Correlative light and electron microscopic results were obtained, indicating the presence of-d-mannose and/or -D-glucose residues detected by the lectin in the rough endoplasmic reticulum region. Quantitation of the electron microscopic cytochemical reaction also showed that the specific labelling was almost exclusively localized in the lumen of endoplasmic reticulum cisternae. No significant staining was found in other membrane compartments or extracellular matrix. This labelling pattern could be considered as the cytochemical evidence ofN-glycosylation processes occurring during the biosynthesis of cartilage extracellular matrix components by chondrocytes.     

Substrate specificity and some properties of phenol sulfotransferase from human intestinal Caco-2 cells

The phase II metabolic reactions, sulfation and glucuronidation, were studied in a human colon carcinoma cell line (Caco-2), which has been developed as a model of intestinal enterocytes. Phenol sulfotransferase (PST, EC 2.4.2.1) was isolated from Caco-2 cells cultured for 7, 14 and 21 days. The enzyme catalyzed the sulfation of both p-nitrophenol and catecholamines (e.g., dopamine) as well as most catecholamine metabolites. The affinity (Km) of PST for dopamine was much higher than for p-nitrophenol, and the specific activity of PST with both substrates increased with the age of the cells. The thermal stability of Caco-2 PST increased with cell age and was not dependent on the acceptor substrate used. The thermolabile PST from 7-day old cells was more sensitive to NEM than was the thermostable enzyme from 21-day old cells. No UDP-glucuronyltransferase (EC 2.4.1.17) activity was detected in 7-, 14- and 21-day old Caco-2 cells with any of the methods used.     

Calcium dependence of the contractile response of the aorta in the rat, rabbit and guinea pig and in the human uterine artery

The influence of extracellular Ca2+ on the contraction produced by noradrenaline (NA) (3 x 10(-6) M), KCl (60 mM) and BaCl2 (30 mM) on human uterine arteries (AUH) and aortic strips from rats, rabbits and guinea-pigs have been studied. The vessels were cut spirally and incubated in Krebs solution containing 2.5 mM Ca2+ (KN), 0 mM Ca2+ (K-0Ca) or 0 mM Ca2+ + 3 mM EDTA (K-EDTA). Both phases (fast and slow) of the response of aortic strips to NA and of the AUH to NA, KCl and BaCl2 were significantly smaller in solutions without Ca2+. Only in rabbit aortic strips the slow phase was significantly more reduced than the fast phase. Overall, the contractions of the rat aortic strips were most resistant to the absence of extracellular Ca2+. These results confirm the variability of the responses of blood vessels from different vascular beds and species to the removal of extracellular Ca2+.     

Ion pathways in transverse tubules. Quantification of receptors in membranes isolated from frog and rabbit skeletal muscle

The presence of four cation pathways in membrane vesicles isolated from transverse tubules of frog and rabbit skeletal muscle was studied by measuring binding of specific blockers. Transverse tubules purified from frog muscle have a maximal binding capacity for [3H]nitrendipine (a marker for voltage-dependent calcium channels) of 130 pmol/mg of protein; this binding is strongly dependent on temperature and, at 37 degrees C, on the presence of diltiazem. Receptors for [3H]ethylenediamine tetrodotoxin (a marker for voltage-dependent sodium channels) and for 125I-labeled alpha-bungarotoxin (a marker for acetylcholine-mediated channels) showed maximal binding values of about 5 pmol/mg. The number of sodium-pumping sites in the isolated tubule vesicles, inferred from [3H]ouabain binding, was 215 pmol/mg. The high purity of this preparation makes feasible the use of these values as a criterion to judge the degree of purity of isolated preparations, and it allows investigation of transverse tubule contamination in other muscle membrane fractions.     

Inhibition of non-genomic responses to oestrogen in the rat uterus by testosterone propionate

Testosterone propionate (50 mg/kg), administered together with oestradiol, inhibited the oestrogen-induced uterine eosinophilia, deep endometrial oedema and the increase in uterine wet weight, 6 h after treatment. The same dose of the androgen decreased the number of eosinophils in the blood and increased their degranulation, explaining the effect of testosterone in the uterus. The high doses of the androgen used were in the range of the doses reported by others to block selectively the oestrogen-induced increase in uterine peroxidase content but not other responses to oestrogen or the cytosolic oestrogen receptor translocation to the nucleus. The dissociation by high doses of testosterone of the oestrogen-induced uterine eosinophilia, wet weight increase and oedema from other responses to oestrogen in the absence of any measurable effect of testosterone upon cytosolic-nuclear oestrogen receptors supports the idea that uterine eosinophilia and oedema are oestrogenic responses regulated by mechanisms different from those of the genomic responses, and is in agreement with the hypothesis of the mediation of uterine oedema by eosinophils.     

Effects of partial hepatectomy on various blood and hepatic parameters in the rainbow trout (Salmo gairdnerii, Rich.)

After 36% of hepatic mass removal , rainbow trout recovered its initial liver weight in 20-30 days, i.e., with a regeneration rate clearly lower than in mammals. During early regeneration process hematocrit index and hemoglobin content were slightly decreased, but both parameters rapidly reached their normal values. The evolution of both glycaemia and hepatic glycogen content supported the idea of the existence of a late regeneration wave, which, in this case, could begin at about the 20th post-operative day.     

Isolation of peroxisomes from frozen human liver samples.

This paper shows the successful isolation of peroxisomes from human liver samples that were kept frozen at -70 degrees C. Purification of these peroxisomes was obtained by a combination of two subcellular fractionation techniques: differential centrifugation and isopycnic fractionation in Nycodenz density gradients. Peroxisome integrity was evaluated by latency measurements and by ultrastructural observation. The procedure described here may be useful for the isolation of other subcellular organelles from frozen human samples.