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Notes: Abstract— The initial rate of uptake of [2,3-3H]gamma-aminobutyric acid by rat brain synaptosomes was studied under incubation conditions in which GABA metabolism was minimal. The presence of both sodium and potassium in the incubation medium was essential for sustained uptake. Uptake proceeded for a short period of time in the absence of potassium and then ceased. No uptake was observed when sodium chloride was completely replaced with sucrose or choline chloride. The sodium-dependence curve for GABA uptake was markedly sigmoid. The sigmoid character of the curve was not attributable to a lag phase in uptake at low sodium concentrations. Calcium strongly stimulated the initial rate of uptake at low sodium concentrations but had little effect at sodium concentrations above 100 mm and was not able to support uptake in the absence of sodium. The sigmoid character of thesodium-dependence curve was completely eliminated by 20 mm calcium ion. Magnesium and phosphate had little effect on the initial rate of GABA uptake.

Notes: In order to be able to monitor dispersion and setting of cements, admixtures can be added, which usually can consist of large organic molecules. Here, the choice is different since small organic molecules have been used as in ceramic processing. This work concerns the preparation of calcium aluminate cement paste in the presence of acetic acid; the water to cement mass ratio is equal to 0.6 and the acid to cement mass ratio, 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu15" location="equation/JACE_00414_mu15.gif"/〉 , ranges between 0 and 0.05. This admixture can have either a retarding or an accelerating effect on cement setting. The retarding effect is because of adsorption of acetate complexes, CaCH3CO2+ positively charged, at the surface of CA particles, negatively charged, which leads to the delay (slowing down) of dissolution; it can reach 52 h (case of 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu16" location="equation/JACE_00414_mu16.gif"/〉 ). When 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu17" location="equation/JACE_00414_mu17.gif"/〉 , there is a remarkable accelerating effect. The setting starts 2 h after mixing the cement with the liquid and is fairly constant for higher acetic acid contents. This rapid setting in acid conditions is because of the formation of hydrated calcium acetate in very low quantities and possibly gibbsite; the setting mechanism is quite different since there is no formation of conventional calcium and aluminum hydrates. As an example, with the highest amount of HOAc ( 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu18" location="equation/JACE_00414_mu18.gif"/〉 ), no CxAyHz type of calcium aluminum hydrate is formed after aging for 4 days at 20°C and 95% relative humidity. There is also a densifying effect of acetic acid; the open porosity of set samples left to age for 4 days at 20°C and 95% relative humidity decreases from 35 to 25 vol% when 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu19" location="equation/JACE_00414_mu19.gif"/〉 goes from 0 to 0.005 and remains relatively constant afterwards. Lastly, this decrease in the porosity continues with aging time; at 6 months, we obtain values as low as 9 vol% in samples where 〈inlineGraphic alt="inline image" href="urn:x-wiley:00027820:JACE00414:JACE_00414_mu20" location="equation/JACE_00414_mu20.gif"/〉.

Notes: Bacterivorous protozoa and bacteria have been in co-existence since the origin of life. This co-existence has led unequivocally to the evolution of many different co-interactions. Most bacteria are ingested and digested, but many escape ingestion for various reasons. Others are ingested but evade digestion, and a few, notoriously Legionella pneumophila, even have the capacity of multiplying within the protozoan host. The aims of this study were to elucidate the interactions of various multi-drug-resistant Staphylococcus aureus (MRSA) strains, Listeria monocytogenes sv4b, and Escherichia coli K12 with the amoeba, Acanthamoeba polyphaga. To evaluate the interactions, we set up co-cultures in Neffs' amoebic saline, at a multiplicity of invasion (MOI) of 1:100 of amoeba to bacteria, and a temperature of 37°C, although the effects of MOI and temperature were also assessed. Survival of bacteria and amoeba was checked at regular intervals, coupled with microscopy. It was discovered under our test conditions, that E. coli was ingested and digested by A. polyphaga, but in contrast, L. monocytogenes, had the capacity to flourish in the presence of A. polyphaga. We also report, for the first time, that all six MRSA isolates tested, survived and replicated in association with A. polyphaga, in comparison to conditions where amoebae were absent. Indeed, we also have evidence suggesting that increases in MRSA, in the presence of A. polyphaga, may be attributable to intracellular survival and replication. These findings have profound implications for the hospital environment, where Acanthamoeba sp., are also commonly isolated. In conclusion, this study illustrates the significance of protozoa as vehicles augmenting the survival of MRSA and L. monocytogenes in the environment.

Notes: The microhabitats favoured by protozoa are dynamic ecosystems comprising a heterogeneous microflora of bacteria and fungi as well as protozoa in a complex biofilm. Many protozoa feed by grazing on microbial biofilms, but they do not do so indiscriminately. A dynamic equilibrium will exist and the nature of the relationship changes depending on environmental conditions. The view of protozoa as the hunter and bacteria as the hunted is now recognised as overly simplistic. Some bacteria not only resist predation by protozoa, but also have become endosymbionts of free-living protozoa, demonstrating adaptation to the otherwise hostile intracellular environment. The concept that protozoa can be reservoirs for some pathogens is more widely appreciated and the catalyst for much of this work came from the observation that Legionella pneumophila infects and multiplies within some species of free-living amoebae. In addition to amplifying cell numbers, the phenotype of intra-protozoal-grown cells is quite distinct from their free-living counterparts cultured on complex laboratory media: altered surface properties, decreased susceptibility to chemical inactivation and antibiotics, and enhanced invasiveness for mammalian cells. There is significant conservation in the genes used by L. pneumophila to parasitize protozoa and macrophages and it has been proposed that co-evolution of bacteria and lower order eukaryotic cells has equipped bacteria both for environmental survival and virulence towards higher order eukaryotes. Other authors have even described protozoa as an “evolutionary gym” enabling L. pneumophila to “train” for its role in invading higher eukaryotic organisms.A growing list of bacteria and fungi that interact with protozoa confirm that the co-evolution between L. pneumophila and protozoa is not unique in nature. An emerging theme amongst many of the micro-organisms associating with protozoa is that they typically are recognised as opportunistic pathogens and many lack a recognised animal host. These features are suggestive of a relationship much closer to symbiosis which becomes parasitic only in special circumstances. The question remains why this is so? The answer could lie in co-evolution with lower order eukaryotic organisms present in biofilms.

Notes: Analysis of medieval luster ceramics seems to indicate that the formation of luster layers could involve an ion exchange between some alkali ions of the glaze (Na+ and K+), and copper and silver cations of the luster raw paint during firing. However, because of the weathering shown by the medieval luster decorations analyzed, conclusive proof is difficult to obtain. A realistic reproduction of the luster decorations has been fabricated in order to follow the process of formation of the luster layer. This has been studied by optical microscopy, transmission electron microscopy, electron probe microanalysis, extended X-ray absorption fine structure, X-ray absorption near-edge structure, and the results give direct evidence that ion exchange and diffusion are the physical–chemical mechanisms responsible for the introduction of copper and silver into the glaze.

Notes: A case of the carcinoid syndrome with unusual skin lesions is described. A rise in blood prostaglandin activity associated with noradrenaline-induccd flushing is reported. The significance of prostaglandins in the carcinoid syndrome is discussed.