Role of cell-mediated immunity in the resistance to experimental sporotrichosis in mice

The in vitro activity of several new imidazoles, cloconazole, sulconazole, butoconazole, isoconazole and fenticonazole, were compared with those of amphothericin B, flucytosine, and three azoles: econazole, miconazole and ketoconazole against isolates of pathogenic Candida. A total of 186 clinical isolates of 10 species of the genus Candida and two culture collection strains were tested by an agar-dilution technique. Isoconazole was the most active azole, followed by butoconazole and sulconazole. Differences between some of the species in their susceptibility to the antifungal agents were noted. Sulconazole and cloconazole had the highest activity in vitro against 106 isolates of C. albicans. Butoconazole and isoconazole were also very active against isolates of C. albicans, and were the most active azole compounds against 80 isolates of Candida spp.     

The influence of RNA-synthesis inhibitors on in vivo pollen tube growth and the self-incompatibility reaction in Lilium longiflorum thunb

Summary Injection of 3 X 10^–4 g/ml acridine orange, 2 X 10^–5 g/ml actinomycin-D, or 1.34 X 10^–3 g/ml 6-methyl-purine in stigmatic exudate into the hollow styles of Lilium longiflorum immediately before, or 6 or 12 hr after pollination restricted compatible pollen tube growth to lengths typical of incompatible tubes. Treatment 24 hr after pollination resulted either in no effect on compatible tube growth or in a significant retardation of compatible tube growth but not to the length of tubes in incompatibly pollinated styles. Aqueous solutions of these inhibitors at the same concentrations injected into lily styles 6 or 12hr before pollination significantly stimulated incompatible pollen tube growth. These results suggest that RNA synthesis in the style is necessary for the self-incompatibility reaction and RNA synthesis in the pollen tube is required for compatible tube growth. The RNA synthesis in the pollen tube may be completed by 24 hr after pollination.Paper number 7439 of the Scientific Journal Series, Minn. Agr. Exp. Sta., St. Paul, Minn. The author gratefully acknowledges the support of the Graduate School, Univ. of Minn. and the United Bulb Co., Mount Clemens, Mich.     

DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

Enhanced susceptibility to cetyl fluoride (CF) and cetyl fluoroacetate (CFA) in DDT-resistant insects

Two compounds showing negative correlation to DDT-resistance in larvae of Musca domestica were found, namely cetyl fluoride (CF) and cetyl fluoroacetate (CFA). Larvae of the DDT-resistant housefly strains K₁ and TP were affected more strongly by CFA incorporated in the breeding medium than larvae of the normal reference strains Sv and S-Rome. The same held true for CF, except that the effect on strain TP was doubtful. The chlordane-resistant, strain R-Sard. had a normal response to CF and CFA. In larvae of several DDT-resistant, laboratory-developed strains of Anopbeles atroparvus, negative correlation to resistance was noted for CF, but not for CFA and cetyl cyanide. The effect of CF applied again only to DDT-resistance, not to dieldrin-resistance.No negative correlation to resistance was found in adults of houseflies and anophelines with regard to CF, CFA, cetyl chloroacetate, cetyl cyanide, cetyl thiocyanate and cetyl bromide.

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Zusammenfassung Cetylfluorid (CF) war gegen Hausfliegenlarven des Schweizer DDT-resistenten Stammes K₁ etwas giftiger als gegen die normalsensiblen Vergleichsstämme Sv und S-Rome; für den DDT-resistenten italienischen Stamm TP war diese Erscheinung jedoch fraglich. Cetylfluorazetat (CFA) wirkte etwas besser auf Larven der beiden DDT-resistenten Fliegenstämme als auf die der Vergleichsstämme. Gegen Anopheleslarven verschiedener DDT-resistenter Stämme, die alle von dem gleichen normalen Ausgangsstamm selektioniert wurden, war CF etwas besser wirksam, als gegen den normalsensiblen Ausgangsstamm. Dagegen konnte weder für CFA noch für Cetylzyanid erhöhte Empfindlichkeit bei resistenten Anopbeleslarven nachgewiesen werden. Die oben geschilderten Preferentialtoxizitäten für resistente Stämme bezogen sich nur auf DDT-Resistenz und waren für Chlordan-oder Dieldrin-Resistenz nicht zutreffend.Ausser dem in früheren Arbeiten geschilderten Fall (Cetylbromazetat bei adulten Hausfliegen) konnten keine neuen Beispiele für durch Resistenz induzierte, erhöhte Empfindlichkeit (Ascher 1958b, 1960) bei Adulttieren der Hausfliege und der Anopbelesmücke gefunden werden; es wurden zu diesem Zweck CF, CFA, Cetylchlorazetat, Cetylzyanid, Cetylrhodanid und Cetylbromid getestet, jedoch waren die Etgebnisse negativ. Verschiedene Cetyl-phosphorsäureester, Cetyl-polyäthylenaether und Alkylbrommalonate waren entweder überhaupt unwirksam oder wiesen bei vorhandener schwacher Wirksamkeit weder gegen Larven noch gegen Adulttiere resistenter Stämme eine preferentielle Toxizität auf.

     

Surface properties of irreversibly sickled cells differ from those of the bulk of sickle cells Studies by partitioning in aqueous phase systems

Counter-current distribution (CCD) of red blood cells (RBC) from individuaks with homozygous sickle cell (HbSS) disease in a charge-sensitive aqueous dextran-poly(ethylene glycol) phase system, which fractionates cells on the basis of surface properties, indicates that the percentage of irreversibly sickled cells (ISC) increases and the percentage of reticulocytes decreases with increasing cell partition ratios. The high partition ratios of ISC correspond to those of older RBC when RBC from normal individuals are subjected to CCD. Our results thus indicate that ISC differ in surface properties from those of the bulk of sickle RBC (including reticulocytes) in the population and that the difference is, most likely, charge-related. While the question as to whether ISC are indeed old cells has not yet been unequivocally answered, this view finds support in the fact that the independent parameters of ISC surface properties, as reflected by partition ratios, and densities correlate as they do in older RBC from normal individuals.     

Generation of lipopolysaccharide-induced interferon in spleen cell cultures

Incubation of murine spleen-cell cultures with lipopolysaccharide (LPS) induces interferon (IF) production. Maximal IF levels are obtained after incubation with 100 g/ml for 10 h. Two inbred mouse strains differing in their ability to generate LPS-induced IF in spleen-cell cultures were used: C3H/eB, which generates high levels of IF (about 60 units/ml), and C3H/HeJ, which fails to generate detectable quantities of IF. In a genetic analysis these strains were hybridized and IF production was determined in spleen-cell cultures from F₁ and F₂ generations, and from backcrosses of F₁ hybrids to parent strains. The results indicate that, in parent strains, a single dominant autosomal gene is responsible for differences in IF production in spleen cultures. LPS-induced IF in spleen-cell cultures resists pH 2 for as long as 48 h, but is labile to heating at 56° C for 30 min. Both macrophages and lymphocytes must be present in cultures for generation of LPS-induced IF. By using mixed cultures of macrophages and lymphocytes from C3H/eB and C3H/HeJ mice, it was shown that macrophages have to interact directly with LPS to enable IF production in the cultures.