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Escherichia coli strains expressing Dr fimbriae are able to enter epithelial cells by interacting with a complement-regulatory protein, decay-accelerating factor. This model of bacterial internalization, with a well-characterized bacterial ligand and host receptor, provides a unique opportunity to investigate the early stages of invasion. We used immunofluorescence staining techniques to examine the distribution of receptor and cytoskeletal proteins in HeLa cells infected with E. coli recombinant strains that expressed Dr family of adhesins: Dr, Dr-II, F1845, AFA-I, and AFA-III. A major rearrangement of decay-accelerating factor was found at the adherence sites of recombinant strains expressing Dr, Dr-II, and F1845 adhesins. The changes in the distribution of receptor were significantly smaller on HeLa cells infected with E. coli bearing AFA-I or AFA-III afimbrial adhesins. Receptor aggregation was associated with the redistribution of cytoskeleton-associated proteins such as actin, alpha-actinin, ezrin, and occasionally tropomyosin. Purified Dr fimbriae coated on polystyrene beads were capable of triggering clustering of receptor and accumulating actin at the adhesion sites of beads to HeLa cells. Using scanning and transmission electron microscopic techniques, we have shown that beads coated with Dr fimbriae, as opposed to beads coated with bovine serum albumin, were enwrapped by cellular microvilli and ultimately internalized into HeLa cells. This indicates that interaction of Dr fimbriae with decay-accelerating factor is associated with redistribution of receptor and is sufficient to promote bacterial internalization.

The contribution of nitric oxide to host resistance to experimental pyelonephritis is not well understood. We examined whether the inhibition of nitric oxide synthesis alters the sensitivity of lipopolysaccharide (LPS) responder (C3H/HeN) and nonresponder (C3H/HeJ) mice to experimental Escherichia coli pyelonephritis. C3H/HeJ and C3H/HeN mice were implanted subcutaneously with minipumps containing an inhibitor of nitric oxide, NG-nitro-L-arginine methyl ester (L-NAME), or a corresponding vehicle. Ascending urinary tract infection by bladder catheterization with two strains of E. coli, an O75 strain bearing Dr fimbriae and an O75 strain bearing P fimbriae, was developed in tested animals. Twenty-four hours following bladder infection, the kidneys of C3H/HeN and C3H/HeJ mice were colonized at a similar rate. However, 5 weeks postinoculation, C3H/HeN mice cleared infection while C3H/HeJ mice showed persistent colonization. Twenty-four hours following infection, C3H/HeN mice treated with L-NAME showed no significant increase of renal tissue infection compared to the saline-treated control group. However, L-NAME-treated C3H/HeJ mice showed an approximately 100-fold increase in E. coli infection rate compared to the saline-treated controls in the Dr+ group but showed no change compared to those in the P+ group. Dissemination of Dr+ E. coli but not P+ E. coli to the liver and uterus was significantly enhanced with L-NAME treatment in C3H/HeJ mice only. Nitric oxide had no direct killing effect on E. coli in vitro. Nitrite production by various organs was found to be significantly lower in C3H/HeJ mice than in C3H/HeN mice. Alteration of nitric oxide and LPS responsiveness was significantly associated with the increased sensitivity of C3H/HeJ mice to experimental Dr+ but not to P+ E. coli pyelonephritis. These findings are consistent with the hypothesis that nitric oxide synthase activity in concert with LPS responsiveness may participate in the antibacterial defense mechanisms of the C3H mouse urinary tract. This phenomenon is strain dependent and possibly related to the invasive properties of E. coli.

A study of the adsorptive behavior of the pesticide 1,3-dichloropropene on kaolinite suspensions as affected by saturating cations yielded “H” class isotherms. Rapid initial adsorption pointed to chemisorption as a cation exchange reaction.

The adsorptive behavior of Dimecron with H-, Na-, and Ca-montmorillonites was studied. The effect of time on adsorption showed that the process was diffusion controlled. Maximum adsorption occurred at pH 6. The adsorption isotherms and desorption experiments provided evidence for a strong nonionic, electrostatic chemisorption of the chemical to the clay surface. Inferences on the protonation of the carbonyl oxygen of Dimecron by H-montmorillonite or the coordination of the metallic cations of montmorillonite through a water bridge to the oxygen of the carbonyl found support from x-ray and infrared studies.

The interaction of telone with acid and base saturated montmorillonite furnished adsorption isotherms which possessed combined features of H(high affinity) and C(linear rising) class isotherms; a fall in pH, an increase in electrical conductivity and formation of chloride ions. The observations were indicative of a process of chemisorption, both at the planar and lateral sites of montmorillonites, followed by penetration and swelling of the substrate micropores with telone. A reaction mechanism for the process of chemisorption has been proposed.

The effect of pH, time and temperature on the interaction of zinc with acid and base saturated dickites has been investigated. Increase in pH resulted in an increase in adsorption of zinc in the higher concentration range. The adsorption increased rapidly and then slowly with increase in the time of interaction. The variation of rate constants and the half times of reaction suggested an exchange process controlled by film and possibly particle diffusion and thereafter fixation processes. The inferences found support from the nature of adsorption isotherms. Temperature affected adsorption with exothermic interactions. The activation energy of adsorption of zinc on Na-dickite was 14.0 kcal mole−1. Изучалось влияние рН,времени и температуры на взаимодействие цинка с диккитом,насыщенным кислотой и основанием. При увеличении рН увеличивалась адсорбция цинка при более высокой степени концентрации. Адсорбция сначала быстро увеличивалась и затем медленнее с увеличением времени взаимодействия. По изменению постоянных скорости и половины времени реакции можно предположить,что процесс обмена контролировался диффузией пленки и возможно частиц и затем процессами фиксации. Эти выводы были подкреплены характером изотерм адсорбции. Воздействие температуры на адсорбцию указывает на экзотермический характер взаимодействий. Активационная энергия адсорбции цинка Na-диккитом была 14,0 KCal мол−1. Der Effekt von pH,Zeit und Temperatur auf die Einwirkung von Zink auf mit Säuren und Basen gesättigten Dickiten wurde investigiert. Eine Erhöhung in pH resultierte in einer Erhöhung in Adsorption von Zink in der höheren Konzentrationsgruppe. Die Adsorption nimmt zuerst schnell zu und dann langsamer mit zunehmender Zeit der Einwirkung. Die Variation der Geschwindigkeitskonstanten und Halbwertszeiten der Reaktionen schlägt eine Austauschprozedur vor,die durch Film-und vielleicht Teilchendiffusion und danach durch eine Bindung kontrolliert wird. Die Folgerungen wurden durch die Natur der Adsorptionisothermen unterstützt. Die Temperatur übte einen Einfluß auf die Adsorption aus-mit exothermischer Wirkung. Die Aktivitäts-energie der Adsorption des Zinks auf Na-Dickit war 14,0 kcal mole−1. L’effet de la température, du pH,et du temps sur l’interaction du zinc avec des dickites saturées d’acide et de base a été investiguée. L’augmentation du pH a résulté en une augmentation de l’adsorption de zinc dans le domaine de haute concentration. L’adsorption a augmenté rapidement et puis lentement avec l’augmentation du temps d’interaction. La variation du taux d’échange et des demi-vies de réaction a suggéré un processus d’échange contrôlé par la diffusion de film et possiblement de particule, et par la suite, de processus de fixation. Ces déductions ont été appuyées par la nature des isothermes d’adsorption. La température a affecté l’adsorption dans les interactions exothermiques. L’énergie d’activation d’adsorption du zinc sur la Na-dickite était 14.0 Kcal mole−1.

The influence of certain additives on the mobility of pesticides was studied by means of a simplified technique. The variations in the Rfvalues of phosphamidon (Dimecron), dichlorvos (DDVP), malathion, ziram, and zineb, with changes in pH and organic matter, and additions of CaCO3, and cationic, and nonionic surfactants to the soils are reported and explained on the basis of adsorption.