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Biomedical subjects

R T Huang

Publications and source records attributed to R T Huang.

At least 37 records · Page 2Linked to original sources

Aminocyclitol resistance in Staphylococcus aureus: presence of plasmids and aminocyclitol-modifying enzymes.

Aminocyclitol resistance in Staphylococcus aureus has been investigated by the analysis of the plasmids and aminocyclitol-modifying enzymes present in several clinical staphylococcal isolates. All of the strains tested were resistant to a broad range of aminocyclitols and contained large plasmids which encoded a variety of aminocyclitol-modifying enzymes in addition to other antibiotic resistances. All strains expressed multiple aminocyclitol-modifying enzymes. The plasmids present in these strains appear to be related by virtue of their similar restriction endonuclease digestion patterns. The plasmids are related and differ by the gain or loss of small DNA segments, one of which encodes erythromycin and kanamycin resistance.

Acetyltransferases↗

Involvement of glycolipids in myxovirus-induced membrane fusion (haemolysis).

Myxoviruses (influenza viruses and paramyxoviruses) penetrate their host cells by fusion of viral and cellular membranes. During this process, virus envelopes react with galactose-terminating glycolipids of cellular membranes. This was suggested by experiments showing the ability of these lipids to inhibit fusion (as measured by haemolysis) when reacted with the viruses, and to enhance it when added as enrichment to erythrocytes.

Erythrocytes↗

Productive infection of chick embryo cells by influenza viruses tightly bound on substratum.

To test whether penetration of influenza viruses could occur at the plasma membrane of host cells, virus particles were tightly bound on Concanavalin A-coated substratum of plastic culture plates and then overlayed with embryo cells. Under these conditions, endocytosis of the viruses was prevented but the cells were found to be effectively infected. The results indicate, that infection by influenza viruses can occur through fusion between the viral membrane and the host cell plasma membrane.

Animals↗

Simple and rapid separation of ortho- and paramyxovirus glycoproteins.

The hemagglutinin (HA) and neuraminidase (NA) of influenza viruses, as well as the fusion protein (F) and hemagglutinin-neuraminidase (HN) of paramyxoviruses, have been separated in native form using a two-step procedure. The glycoproteins are efficiently extracted from virions using the on-ionic detergent octyl-beta-D-glucoside and are then applied to a column of agarose beads coupled with tyrosine-sulfanilic acid. Pure HA and F are obtained in good yield in the flow-through from this column. NA and HN bind strongly and can be eluted, albeit somewhat contaminated with HA or F, by raising the pH of the column buffer. The separated non-denatured fractions can be used for structural, functional, and antigenic studies.

Chromatography, Affinity↗

On the structure of the carbohydrate chains of different strains of the influenza virus.

Structural features of the glycosyl chains of the influenca virus have been determined. It was found that fucose was solely terminal, whereas mannose and galactose were present at the terminal as well as subterminal and core positions. Mannose and glucose molecules were shown to be branching points in the glycosyl chains. Furthermore, linkage positions of carbohydrates within the chains were characterized.

Carbohydrates↗

Sphingolipids of influenza viruses.

Total lipid of four egg grown influenza viruses (A2-Asia, A2-England, A2-Taiwan and fowl plague virus) were extracted with chloroform-methanol. After mild alkali treatment of the extracts, glycosphingolipids and sphingomyelin were separated by a silicic acid column, and finally purified by thin layer chromatography. Fatty acid, sphingosine and carbohydrate components of individual lipid classes were then analysed by gas-liquid chromatography. Nearly identical results were obtained with all viruses investigated. Approximately 20% of the total lipid was monohexosylceramide, distributed equally between glucosyl- and galactosyl- analogues. Lactosylceramide and oligohexosylceramides were found in much smaller concentrations (approx. 2%). About 15% of the total lipid was attributed to sphingomyelin. A large proportion of fatty acids (around 25% in sphingomyelin and 60% in glycolipids) belonged to the long chain (C19-C26) normal- and 2-hydroxy series. C18-sphingosine was found to be the only base present in all lipid classes investigated.

Fatty Acids↗