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R F SMITH

Publications and source records attributed to R F SMITH.

At least 19 recordsLinked to original sources
PubMed1964

THE SPECIFICITY OF ALLERGIC REACTIONS. VII. IMMUNOLOGIC UNRESPONSIVENSSS, DELAYED HYPERSENSITIVITY, AND CIRCULATING ANTIBODY TO PROTEINS AND HAPTEN-PROTEIN CONJUGATES IN ADULT GUINEA PIGS.

Adult guinea pigs were made unresponsive to a heterologous protein (e.g. bovine gamma globulin, or BGG) or a hapten-protein conjugate (e.g. p-aminobenzoic acid-bovine gamma globulin, or PABAgammamiddot;BGG) by intraperitoneal injection of 80 mg cyclophosphamide and the specific antigen. This immunologic unresponsiveness developed to the specific antigen administered simultaneously with the cyclophosphamide, and not to any variants. Thus, animals unresponsive to PABAgammamiddot;BGG remained unresponsive to the original antigen on challenge with a variant, but formed delayed hypersensitivity and circulating antibody to the variant. The specificity of immunologic unresponsiveness, therefore, seems more closely related to the whole antigen molecule than does delayed hypersensitivity.

Animals↗
PubMed1963

EFFECTS OF PROTEIN, LIPIDS, AND SURFACTANTS ON THE ANTIMICROBIAL ACTIVITY OF SYNTHETIC STEROIDS.

Three 4-azacholestanes and two A-norcholestanes were inactivated by 10 and 20% bovine serum and by 1.0, 2.5, and 5.0% sheep blood. The five compounds exhibited hemolytic properties when tested with 2% sheep blood and 2% human blood. These cholestanes inhibited Streptococcus pyogenes and were completely inactivated by 0.1% lecithin. Tween 80 was comparable to lecithin in causing the inactivation of steroids; 1% polyethylene glycol-4000 was inert; 1% Tween 20 and 1.0% Span 20 caused the inactivation of 3beta,4-dimethyl-4-aza-5alpha-cholestane (ND-307). The sodium salts of four fatty acids, oleate, stearate, deoxycholate, and lauryl sulfate (0.1 to 1.0 mg/ml), effectively interfered with the action of ND-307. The steroids appear to have some properties similar to those of antimicrobial surfactants of the cationic type but have certain distinct features.

Animals↗
PubMed1963

ANTIMICROBIAL ACTION OF NITROGEN-CONTAINING STEROIDS.

Smith, Rodney F. (University of Maryland, Baltimore), Donald E. Shay, and Norman J. Doorenbos. Antimicrobial action of nitrogen-containing steroids. J. Bacteriol. 85:1295-1299. 1963.-A new group of 16 synthetic nitrogen-containing steroids have been tested against a variety of microorganisms for antimicrobial properties. The gradient plate screening method, serial dilution, and dry weight techniques were used in the studies. The organisms tested consisted of 14 gram-negative bacteria, 10 gram-positive bacteria, 2 actinomycetes, 7 yeasts, and 8 molds. Inhibitory properties were found to be specific and potent in four compounds, with inhibitory concentrations as low as 0.37 mug/ml. Three of the active steroids are 4-aza cholestanes and one is a 4-nor-3,5-secocholestane amide. Sensitivity to the compounds was greatest in the gram-positive bacteria, followed by the yeasts and molds. The gram-negative bacteria were not inhibited. All 16 steroids interfered to some extent with pigmentation in Serratia marcescens but not with pigment production in Pseudomonas aeruginosa. In a few instances, some of the molds were stimulated by the steroids at a concentration of 250 mug/ml.

Actinomycetales↗
PubMed1962

Hypersensitivity in newborn guinea pigs.

Neonatal guinea pigs during the first 2 weeks of life did not indicate the presence of delayed hypersensitivity intradermally, after sensitization with purified soluble antigens in dose levels that induced detectable delayed hypersensitivity in the skin of adults. Although Arthus type allergy was detectable in newborns, circulating antibody frequently preceded its appearance by several days. Passive Arthus reactions were not produced in newborns as readily as in adults. Contact hypersensitivity and allergic encephalomyelitis were induced in newborns, but corneal reactions were not. Total body irradiation with 200 r inhibited antibody formation in newborns, as in adults. In addition, the induction period for anamnestic responses in newborns and the antigen elimination rate were the same as in adults. Passive transfer of delayed hypersensitivity from sensitized newborns to normal adults was accomplished.

Animals↗