Changes were found in the cell structure of the root meristems of Haemanthus albiflos and Allium cepa treated with methotrexate, an oncostatic preparation of the antimetabolite group. Root culture was conducted under anaerorbic conditions to induce In this way glycolysis typical for neoplastic cells. In Haemanthus, where the glycolytilc process runs normally, hypertrophy of the rough ER membranes noted correlated with the presence of numerous mitochondria and dictyasames with changed Structure. In Allium cells, where the glycalytic process runs with the participation of alliin, methotrexate did not evoke development of ER membranes. The structure of mitochondria and dictyosomes was similar as that in the root meristem of Haemanthus. In both studied objects thickening of the cell wall was noted.
Vitamin A is known to exert an important influence on epithelial differentiation. The fetal calf serum supplement of cell-culture medium contains enough of the vitamin to affect the differentiation of cultured keratinocytes derived from epidermis and from other stratified squamous epithelia. The cellular and molecular properties of the cultures are altered when the medium is supplemented with serum from which the vitamin A has been removed by solvent extraction (delipidized serum). Cell motility is reduced, the adhesiveness of cells increases and pattern formation is prevented. In both epidermal and conjunctival keratinocytes, removal of vitamin A leads to the synthesis of a 67 kd keratin characteristic of terminally differentiating epidermis and to much reduced synthesis of the 52 kd and 40 kd keratins typical of conjunctiva. These changes, both cellular and molecular, are reversed by the addition of retinyl acetate to the medium containing delipidized serum. Cell motility and pattern formation are restored, and detachment of the most mature cells from the surface of the stratified epithelium is promoted. Synthesis of the 67 kd keratin is prevented and the synthesis of the 40 and 52 kd keratins is stimulated. The nature of the keratins synthesized is regulated by the concentration of vitamin A, and each cell type adjusts its synthesis differently at a given vitamin concentration.
Several clonal lines of cultured Leydig tumor cells have been established and characterized in terms of gonadotropin receptors and steroid production. Although freshly isolated cells derived from the M5480P tumor have functional hCG receptors, only two of the five clonal lines established were shown to bind significant quantities of hCG. In these clones, steroid production can be stimulated to the same extent by hCG, cholera toxin, and 8-Br-cAMP. The other three clones bind a small amount of hCG and respond to the hormone with a marginal increase in steroidogenesis. Steroid production, however, is significantly stimulated by cholera toxin or 8-Br-cAMP. A comparison of the steroids produced by freshly isolated cells and two of the clones revealed some changes in the steroidogenic pathway. The most obvious change is an increase in the ability of the cultured cells to synthesize 20 alpha-dihydroprogesterone (20 alpha-hydroxypregn-4-en-3-one). These clonal lines may provide a suitable model system for the study of gonadotropin actions and regulation of the expression of differentiated functions of Leydig cells.
Human low density lipoprotein (LDL) was incubated with an established line of rabbit aortic endothelial cells. Density gradient fractionation showed a time-, concentration-, and temperature-dependent increase in the average density of the LDL (from about 1.036 to as high as 1.070 g/ml). Incubation without cells or with other types of cultured cells (fibroblasts, hepatocytes, 3T3-L1 cells) caused no significant change in density. I-Labeled LDL ( I-LDL) recovered after incubation with endothelial cells (EC-modified LDL) was taken up and degraded 3 to 4 times more rapidly than control LDL by resident mouse peritoneal macrophages and by an established tumor line of mouse macrophages (J774 cells). Macrophage degradation of EC-modified I-LDL exhibited saturation kinetics ($>$85% inhibited by excess unlabeled EC-modified LDL). Degradation was also inhibited by unlabeled acetylated LDL and, conversely, unlabeled EC-modified LDL inhibited degradation of acetylated I-LDL. Incubation of LDL with conditioned medium removed from endothelial cell cultures modified neither its density nor its rate of degradation by macrophages. These studies show that endothelial cells have the potential to metabolically modify the LDL molecule, generating a form that is more rapidly degraded by macrophages and that is recognized by the macrophage receptor for acetylated LDL. This process may play a significant role in the pathogenesis of atherosclerosis.
The cells from a small piece of epidermis can be grown into a large number of cultured epithelia. Such epithelia, generated from autologous skin, were grafted onto full-thickness burn wounds in two patients. The cultured epithelia acquired an epidermal structure resembling that achieved with conventional split-thickness skin grafts, and survived for the period of observation (up to 8 months). Since the method of cultivation can generate large amounts of epithelium, the procedure is applicable to the grafting of large areas, as in severe burns.
Diazepam and (-)-pentobarbital each potentiate the increase in chloride ion conductance produced by γ -aminobutyric acid (GABA) in voltage-clamped mouse spinal neurons grown in culture. Fluctuation analysis was used to compare the properties of elementary ion-channel events underlying the chloride conductance produced by GABA alone and during potentiation by the two drugs. Neither drug altered the conductance of an open ion channel, but both drugs affected the kinetics of channel activity. Diazepam increased the frequency of channel openings and either did not affect or slightly increased the average open-channel lifetime, whereas (-)-pentobarbital decreased the frequency of channel openings and increased average open-channel lifetime. These changes in the kinetics of GABA-activated ion channels can quantitatively account for the potentiation of GABA responses observed with the drugs. Thus, the drugs each increase the response to GABA but do not act on channel kinetics in the same manner.
Background: Magnolol, a compound isolated from the cortex of Magnolia officinalis, has been found to possess anti-allergic and anti-asthmatic activity. Methods: The effect of magnolol on ionic currents was studied in cultured smooth muscle cells of human trachea with the aid of the patch clamp technique. Results: In whole cell current recordings magnolol reversibly increased the amplitude of K+ outward currents. The increase in outward current caused by magnolol was sensitive to inhibition by iberiotoxin (200 nM) or paxilline (1 μM) but not by glibenclamide (10 μM). In inside out patches, magnolol added to the bath did not modify single channel conductance but effectively enhanced the activity of large conductance Ca2+ activated K+ (BKCa) channels. Magnolol increased the probability of these channel openings in a concentration dependent manner with an EC50 value of 1.5 μM. The magnolol stimulated increase in the probability of channels opening was independent of internal Ca2+. The application of magnolol also shifted the activation curve of BKCa channels to less positive membrane potentials. The change in the kinetic behaviour of BKCa channels caused by magnolol in these cells is the result of an increase in dissociation and gating constants. Conclusions: These results provide evidence that, in addition to the presence of antioxidative activity, magnolol is potent in stimulating BKCa channel activity in tracheal smooth muscle cells. The direct stimulation of these BKCa channels by magnolol may contribute to the underlying mechanism by which it acts as an anti-asthmatic compound.,The Till-U-Test Candida Dermatophyte (TUT CD) culture slide, produced for the diagnosis of yeast and dermatophyte infections, was compared with microscopy and formal laboratory culture in the diagnosis of vaginal candidosis. Candida albicans grew readily on the medium and reliable results were obtained within a mean of three days' incubation at room temperature. Agreement with laboratory culture was 91 . 4%; 29% of cases would have been missed by microscopy alone. The TUT CD is a useful device, therefore, in the investigation of vaginitis.
Certain metabolic properties of hormonally responsive osteogenic sarcoma cells derived from a transplantable rat tumor have been compared with those of related normal rat bone cells. All studies were carried out on cells grown in monolayer culture. Normal rat bone cells derived by repeated collagenase/trypsin digestion of newborn rat calvaria. Bone cells selected for comparison were thought to be osteoblast-like, as judged by enrichment of alkaline phosphatase and adenylate cyclase responsiveness to parathyroid hormone and prostaglandin E2. The adenylate cyclases of the two cell strains were similarly stimulated by a range of prostanoids and their metabolites and analogs. Morphology showed the two cell strains to be similar; the only obvious difference was a multilayering of cells in the sarcoma cultures, while the normal cultures showed abundant extracellular fibril formation which was not seen in the tumor cells. Investigation of the cAMP-dependent protein kinase isoenzymes showed the presence of two forms in both cell types, one eluting at a low salt concentration and the other at a high salt concentration. There was approximately twice the amount of the first isoenzyme compared to the second isoenzyme. The results indicate the usefulness of the two cell strains to elucidate further the molecular mechanisms of action of parathyroid hormone and prostaglandins.