Search results for "VITRO"
showing 10 items of 2786 documents
Effects of gadolinium and cadmium on the electrically evoked release of 45calcium from the isolated rat neurohypophysis.
1988
Isolated neural lobes of the rat pituitary gland were fixed by their stalks to a platinum wire electrode. They were loaded with 45calcium and then superfused with radioactivity-free Krebs-solution. The efflux of 45calcium into the superfusion medium was determined. After 54–60 min of superfusion the spontaneous outflow of 45calcium was 2.03%/min of the tissue 45calcium. It was not affected by cadmium (Cd2+, 0.03-3 mmol/1), but reduced by 40% in the presence of 1 mmol/1 gadolinium (Gd3). Electrical stimulation with pulses of 15 Hz (3 times for 1 min with intervals of 1 min) evoked a 45calcium release of 14.4% of the tissue radioactivity. The evoked release of 45calcium was reduced by 80% in …
Effects of tetraethylammonium ions on frequency-dependent vasopressin release from the rat neurohypophysis.
1988
1. Isolated rat neurohypophyses were fixed by their stalks to a platinum wire electrode and superfused with oxygenated Krebs-HEPES solution. Vasopressin release into the medium was determined by radioimmunoassay. Vasopressin secretion was increased by electrical stimulation at different frequencies (3-30 Hz) and different train lengths (75-900 pulses). The effects of tetraethylammonium (TEA) ions and of enhanced calcium were tested. 2. Electrical stimulation at 7.5 or 15 Hz evoked a markedly larger release of vasopressin than stimulation at 3 Hz. During continuous stimulation at 7.5 and 15 Hz the evoked vasopressin release per pulse declined rapidly, but with similar time constants for both…
Phosphatidylinositol phosphate kinase type I gamma regulates dynamics of large dense-core vesicle fusion.
2005
Phosphatidylinositol-4,5-bisphosphate was proposed to be an important regulator of large dense-core vesicle exocytosis from neuroendocrine tissues. Here, we have examined the kinetics of secretion in chromaffin cells from mice lacking phosphatidylinositol phosphate kinase type Iγ, the major neuronal phosphatidylinositol-4-phosphate 5-kinase. Absence of this enzyme caused a reduction of the readily releasable vesicle pool and its refilling rate, with a small increase in morphologically docked vesicles, indicating a defect in vesicle priming. Furthermore, amperometry revealed a delay in fusion pore expansion. These results provide direct genetic evidence for a key role of phosphatidylinositol…
Fisiopatologia. — Membrane vesicles, shed from in vitro cultured human breast carcinomas cells, inhibit lymphocytes proliferation.
1994
Membrane vesicles are released by the cells of the two human breast carcinoma cell lines 8701-BC and MCF-7. Vesicles express on their surface HLA Class I molecules and tumor associated antigens and they appear to have a strong, dose dependent, inhibitory effect on thymidine incorporation by periferal lymphocytes. Inhibition is evident on both PhA stimulated or non stimulated lymphocytes. The inhibitory effect is visible after three days of culture. Vesicle addition does not cause cytotoxic effects since inhibited lymphocytes are still capable to exclude Trypan blue. No apoptoptic cells were observed.
Chondroitin AC lyase activity is related to virulence of fish pathogenic Flavobacterium columnare.
2006
The virulence of eight Flavobacterium columnare strains was studied to find correlations between several virulence-related factors and virulence. Virulence was tested in vivo using rainbow trout, Oncorhynchus mykiss (Walbaum). Suggested virulence-related factors such as production of the degradative enzyme chondroitin lyase, plasmid occurrence and adhesion capability were studied in vitro. Infection with the four most virulent strains resulted in 95-100% mortality within 114 h. Chondroitin lyase activity was found to be significantly related to the virulence of the strains at 25 degrees C and it was also shown to be temperature-dependent, being higher at 25 degrees C than at 20 degrees C. V…
European Sea Bass (Dicentrarchus labrax) immune status and disease resistance are impaired by arginine dietary supplementation
2015
Infectious diseases and fish feeds management are probably the major expenses in the aquaculture business. Hence, it is a priority to define sustainable strategies which simultaneously avoid therapeutic procedures and reinforce fish immunity. Currently, one preferred approach is the use of immunostimulants which can be supplemented to the fish diets. Arginine is a versatile amino acid with important mechanisms closely related to the immune response. Aiming at finding out how arginine affects the innate immune status or improve disease resistance of European seabass (Dicentrarchus labrax) against vibriosis, fish were fed two arginine-supplemented diets (1% and 2% arginine supplementation). A…
Effects of Tumor Necrosis Factor-Alpha on Growth and Doxorubicin Sensitivity of Multidrug Resistant Tumor Cell Lines
1993
Biological agents might offer various therapeutic opportunities in the treatment of cancer, including a direct and/or host- mediated antiproliferative effect as well as the possibility to favourably modulate tumor sensitivity to antineoplastic drugs (Alexander et al., 1987; Kikuchi et al., 1992; Wadler and Schwartz, 1990). However, information on their activity on chemoresistant tumors is still scanty (Billi et al., 1991; Bonavida et al., 1989; D’Alessandro, 1993; Fruehauf et al., 1991; Liddill et al., 1988; Mihich and Ehrke, 1991). Here we have focused on tumor necrosis-alpha (TNF-α) and studied its in vitro effects on the growth of two tumor cell lines, the mouse B16 melanoma and Friend e…
Contribution of vitamin A to the oxidation resistance of human low density lipoproteins.
1995
This study investigated the antioxidant contribution of vitamin A in protecting human low density lipoprotein (LDL) against copper-stimulated oxidation. The presence of small amounts of retinol (0.033 ± 0.012 nmol/mol LDL) and retinyl palmitate (0.036 ± 0.021 nmol/mol LDL) was routinely ascertained in the LDL. A single oral supplementation with 20,000 IU vitamin A caused a two- to three-fold increase of retinol and retinyl palmitate in the LDL isolated 8 h after the supplementation. In comparison to autologous-control LDL, vitamin A-enriched LDL were more resistant to oxidation, as expressed both by a clear delay in the onset of lipid peroxidation and by a reduction of the rate of conjugate…
Influence of storage and in vitro gastrointestinal digestion on totqal antioxidant capacity of fruit beverages
2011
Eight fruit beverages containing grape, orange and apricot, with/without iron and/or zinc and with/without milk added were analyzed for total antioxidant capacity (ORAC and TEAC methods), ascorbic acid content, and total polyphenols. The influence of cold storage (2-4 degrees C) during the product shelf-life (135 days) and antioxidant capacity after an in vitro gastrointestinal digestion were evaluated. Antioxidant capacity for all beverages together increased significantly (p < 0.05) at the end of storage (16.4% and 12.8% for ORAC and TEAC, respectively), whereas ascorbic acid remained stable. Regarding in vitro digestion, antioxidant values of bioaccessible fractions of fruit beverages in…
Retention–property relationships of anticonvulsant drugs by biopartitioning micellar chromatography
2001
Epilepsy may be considered as a group of disorders with only one thing in common: the fact that recurrent anomalous electrochemical phenomena appear in the central nervous system. Different classes of drugs are included under the generic term of anticonvulsant drugs. All of them work by decreasing discharge propagation in different ways. Biopartitioning micellar chromatography (BMC) is a mode of reversed-phase liquid chromatography, which can be used as an in vitro system to model the biopartitioning process of drugs when there are no active processes. In this paper, relationships between the BMC retention data of anticonvulsant drugs, their pharmacokinetics (oral absorption, protein bindin…