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Biomedical subjects

A Gardas

Publications and source records attributed to A Gardas.

At least 55 records · Page 3Linked to original sources
PubMed1981

Thyrotrophin binding glycoprotein isolated from bovine thyroid.

A butanol-water extraction of bovine thyroid plasma membranes was used to solubilize a thyrotrophin receptor. This method was found to solubilize approximately 12% of membrane proteins and 40% of the binding capacity of thyroid membranes for [125I]TSH. Thyrotrophin binding proteins were further purified 10 times over the butanol-water extract and 70 times over the plasma membranes by means of chromatography on DEAE-cellulose and AcA-54 Ultrogel columns. Purified fractions were found to be glycoproteins containing galactose, mannose, galactosamine, glucosamine and sialic acid. A minute amount (6.0 micrograms per sample) of two glycoprotein fractions obtained after chromatography on AcA-54 Ultrogel caused about 50% inhibition of [125I]TSH binding to thyroid plasma membranes. This inhibition was due to specific interaction between thyrotrophin and isolated glycoproteins.

Animals↗
PubMed1981

Presence of gangliosides in the structure of membrane receptor for thyrotrophin.

Thyroid gangliosides were isolated from bovine thyroid tissue. Neutral lipids and glycolipids were removed by chromatography on a DEAE-cellulose column and residual acidic phospholipids by alkaline degradation. Thyroid gangliosides were separated by chromatography on a silica acid column into 9 different fractions. Thyroid gangliosides were found to be active in the inhibition of [125I]TSH binding to thyroid plasma membranes and this results from a direct action between thyrotrophin and gangliosides. The most active fraction contained gangliosides with two sialic acids per molecule. Pre-incubation of thyroid plasma membranes for 4 hours at 37 degrees C with gangliosides and removal of the unbound gangliosides increased the [125I]TSH binding to pre-treated membranes by 10-20%. Anti-ganglioside antibodies obtained by immunisation of rabbits inhibited [125I]TSH binding to thyroid plasma membranes by 60 to 80%. The thyroxine (T4) level in blood serum of immunized animals was significantly decreased after the first immunization and T4 become almost undetectable after the booster injection implying that antibodies against thyroid gangliosides produce severe impairment of thyroid cell function.

Animals↗
PubMed1980

Isolation and characterization of an endo-beta-galactosidase from a new strain of Escherichia freundii.

A new strain of Escherichia freundii was isolated from human feces. Compared with the previous strain (Kitamikado, M., and Ueno, R. (1970) Bull. Jpn. Soc. Sci. Fish. 36, 1175-1180), this strain releases comparable levels of endo-beta-galactosidase with lower levels of exoglycosidases in the culture medium containing 0.3% of keratan sulfate. Endo-beta-galactosidase was purified by an improved purification procedure involving Amicon H1P10 hollow fiber filtration, QAE-Sephadex A-50, and CM-Sephadex C-50 chromatographies. The purified enzyme is completely free from proteases and exoglycosidases. The general properties of this enzyme are: molecular weight, 28,000; optimal pH, 5.5 TO 5.8; PI, pH 8.0. This enzyme hydrolyzed keratan sulfates isolated from different sources to produce 6-O-sulfo-GlcNAc beta1 leads to 3Gal as the major product. In addition, the specificity of this enzyme toward various glycoconjugates was also studied.

Animals↗
PubMed1979

Microinjection of ricin entrapped in unilamellar liposomes into a ricin-resistant mutant of baby hamster kidney cells.

Fluorescein-labelled Ricin was entrapped in unilamellar liposomes; 14 microgram of protein was entrapped by 1 mg of lipids. Liposomes added to cells in culture in low serum medium can deliver entrapped Ricin to a Ricin-resistant mutant of baby hamster kidney(BHK)cells. Ricin entrapped in unilamellar liposomes inhibits protein biosynthesis at a concentration of 1.75 microgram/ml in Ricin-resistant cells. Ricin dissolved in medium at 50 microgram/ml does not affect protein synthesis in these cells.

Animals↗