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Biomedical subjects

S Harshman

Publications and source records attributed to S Harshman.

At least 37 records · Page 2Linked to original sources
PubMed1978

Specific binding of staphylococcal alpha-toxin to isolated rabbit vagus nerves in vitro.

The binding of staphylococcal [125I]alpha-toxin to rabbit vagus nerves in vitro was a saturable process. The radiolabeled alpha-toxin binding was reduced by the coaddition of added navive alpha-toxin, indicating that the binding is specific. Sucrose gradient analysis of detergent-extracted complexes of [125I]alpha-toxin-rabbit vagus nerves showed both high and low S-value peaks analogous to those observed with similarly treated alpha-toxin-rabbit erythrocyte preparations (P. Cassidy and S. Harshman, Biochemistry, in press).

Animals↗
PubMed1978

Enhancement of hemolytic and cytotoxic activity of staphylococcal alpha-toxin in vitro by incubation with cultured fibroblasts. Brief communication.

Staphylococcal alpha-toxin (alpha-toxin) was incubated with 3T3 or SV40-virus transformed mouse 3T3 fibroblasts during 2 hrs at room temperature. This resulted in about a two-fold increase in the hemolytic activity of alpha-toxin toward rabbit RBC. The concentration of alpha-toxin causing 50% hemolysis of rabbit RBC was lowered from about 120 ng/ml to about 65 ng/ml. Release of 86Rb from labeled RBC and isolated rabbit vagus nerves also occured at lower concentrations of alpha-toxin after preincubation with fibroblasts. The enhancement of hemolytic activity of alpha-toxin was still exerted by cultured fibroblasts preheated to 56 degrees C, but fibroblasts exposed to 100 degrees C were ineffective. The hemolytic activity of alpha-toxin toward rabbit RBC was also slightly enhanced by leucine aminopeptidase (5--20 microgram/ml) and aminopeptidase M (30--300 IU/ml).

Animals↗
PubMed1977

Some immunological effects of penicillamine.

Immunological effects of D- and D,L-penicillamine (PA) were studied in efforts to develop assays for synthetic D or D,L analogs and to contribute to the understanding of the mechanism(s) of action of D-PA in rheumatoid arthritis. At the highest doses tolerated by mice, D,L-PA did not significantly inhibit the development of haemagglutinating antibodies in vivo. In studies in vitro with T lymphocytes, D-PA at 1 mM concentration inhibited both concanavalin A- and phytohaemagglutinin-induced transformation as assayed by [3H]thymidine incorporation, but D-PA concentrations of 5 mM were required to inhibit concanavalin A-induced amino acid uptake. No effect of D-PA was observed either on the induction of cytotoxic T cells or on the attack of specifically sensitized T cells on target cells. It is of interest that D-PA at 1 mM concentration did inhibit lipopolysaccharide-induced transformation, which predominately stimulates B lymphocytes. The effects of PA on the induced transformation of T and B cells deserve further attention for studies with analogs of PA.

Animals↗
PubMed1976

Iodination of a tyrosyl residue in staphylococcal alpha-toxin.

Iodination of staphylococcal alpha-toxin by the lactoperoxidase method resulted in the maximal incorporation of about 2.5 atoms of iodine per molecule of alpha-toxin. The iodination primarily involved a single tyrosine residue as shown by analysis of both cyanogen bromide and tryptic peptides. Iodination at a level of 1.2 iodine atoms per alpha-toxin molecule led to a dramatic decrease in the hemolytic and lethal activities, although no decrease in the binding of iodinated toxin to rabbit erythrocytes was observed (Cassidy and Harshman (1976), Biochemistry, the following paper in this issue). Monoiodinated alpha-toxin was found to have 15% of the specific hemolytic activity of native alpha-toxin. Incubation of rabbit erythrocytes with iodinated alpha-toxin led to a significant protection from the hemolytic activity of native alpha-toxin added later. The results show the modification of a single unique tyrosyl residue in alpha-toxin permits the resolution of alpha-toxin's biological activities from its cell binding activity.

Amino Acids↗
PubMed1976

Studies on the binding of staphylococcal 125I-labeled alpha-toxin to rabbit erythrocytes.

Staphylococcal alpha-toxin, a hemolytic exotoxin, can be iodinated using the lactoperoxidase method. 125 I-Labeled alpha-toxin binds to rabbit erythrocytes in an apparently irreversible and highly specific manner. The binding of 125 I-labeled alpha-toxin to erythrocytes of rabbit and human reflects the species specificity of native alpha-toxin. Binding of 125I-labeled alpha-toxin is blocked by the presence of native alpha-toxin, 127I-labeled alpha-toxin, or anti-alpha-toxin antibody. Simultaneous assays of 125I-labeled alpha-toxin binding and leakage of intracellular 86Rb+ suggest that toxin binding and membrane damage are separate, sequential functions. Both the rate and extent of binding are temperature dependent. Rabbit erythrocytes possess 5 X 10(3) binding sites/cell, while human erythrocytes possess no detectable binding sites. Treatment of rabbit erythrocytes with 125I-labeled alpha-toxin appears to decrease the number of unoccupied binding sites. Chaotropic ions can inhibit 125I-labeled alpha-toxin binding and cause bound 125I-labeled alpha-toxin to dissociate from rabbit erythrocyte membranes. Treatment of intact rabbit erythrocytes with pronase reduces both the binding capacity of the cells for 125I-labeled alpha-toxin, and the cells' sensitivity to hemolysis by native alpha-toxin. It is proposed that the primary binding site for alpha-toxin in biomembranes is a surface membrane protein.

Animals↗
PubMed1976

Protein purification: adsorption chromatography on controlled pore glass with the use of chaotropic buffers.

Chromatography on controlled pore glass in combination with chaotropic buffers makes possible, in a single step, protein purifications of several hundredfold. The new emphasis is on highly selective controllable adsorption. The method is useful for the purification and concentration of proteins from large volumes of complex media and for the purification of proteins that are poorly soluble or tend to aggregate in aqueous solution D-(-)-Beta-Hydroxybutyrate dehydrogenase, a mitochondrial membrane-bound protein, several soluble proteins, and staphylococcal alpha toxin, which can be purified directly from large volumes of culture medium, are used to illustrate the method.

Adsorption↗
PubMed1976

Purification of staphylococcal alpha-toxin by adsorption chromatography on glass.

Staphylococcal alpha-toxin was purified from Staphylococcus aureus growth medium using adsorption chromatography on controlled pore glass beads. Elution of alpha-toxin from the unmodified glass surface of the beads with various anions generally followed the chaotropic series. Alpha-toxin, purified by glass bead chromatography, is composed of a single electrophoretic form, containing less than 2% of other forms.

Adsorption↗