Molecular Epidemiology of Carbapenem Non-Susceptible Acinetobacter baumannii in France

Carbapenem-resistant Acinetobacter baumannii have emerged globally. The objective of this study was to investigate the epidemiology, clonal diversity and resistance mechanisms of imipenem non-susceptible A. baumannii isolates in France. Between December 2010 and August 2011, 132 notifications were collected, including 37 outbreaks corresponding to 242 cases (2 to 55 per cluster). Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on 110 non-repetitive isolates. Gene bla _OXA-23 was the most frequently detected (82%), followed by bla _OXA-24 (11%) and bla _OXA-58 (7%). Eleven sequence types (ST) were distinguished, among which sequence types ST1, ST2 (64%), ST20, ST25, ST85 and ST107. Isolates from epidemiological clusters had the same ST and resistance genes, indicating probable transmission within centres. In contrast, PFGE types of isolates differed among centres, arguing against transmission among centers. This study provides the first epidemiological snapshot of the population of A. baumannii with reduced susceptibility to carbapenems from France, and further underlines the predominance of international clones.     

Interaction between delta and epsilon subunits of F1-ATPase from pig heart mitochondria. Circular dichroism and intrinsic fluorescence of purified and reconstituted delta epsilon complex

A delta epsilon complex has been purified as a molecular entity from pig heart mitochondrial F1-ATPase. This delta epsilon complex has also been reconstituted from purified delta and epsilon subunits. Both isolated and reconstituted delta epsilon complexes have delta 1 epsilon 1 stoichiometry and are indistinguishable by their chromatographic behavior, their circular dichroism spectra (CD spectra), and their intrinsic fluorescence features. The content of secondary structures deduced from CD spectra of the delta epsilon complex appears to be the sum of the respective contributions of purified delta and epsilon subunits. All intrinsic fluorescence studies carried out on isolated epsilon subunit and delta epsilon complex show that the single tryptophan residue located on epsilon is involved in the interaction between delta and epsilon subunits. Results obtained with F1-ATPase are in favor of the same delta epsilon interaction in the entire enzyme.     

Bemerkungen zur Analyse des Reizgeschehens und der funktionellen Anpassung sowie zum Anteil dieser Anpassung an der Entwicklung des Reiches der Lebewesen

Ohne Zusammenfassung     

Salt Content Impacts Food Preferences and Intake among Children

Decreasing dietary sodium intake, which can be achieved by reducing salt content in food, is recommended. Salt contributes to the taste of foods and makes them more enjoyable. Whether a food is liked or disliked is an important determinant of food intake, especially among children. However, the role of salt in children''s food acceptance has received little attention. The impact of salt content on children''s hedonic rating and intake of two foods was investigated in children. Using a within-subject crossover design, we recruited 75 children (8–11 years) to participate in five lunches in their school cafeteria. The target foods were green beans and pasta. The added salt content was 0, 0.6 or 1.2 g/100 g. The children''s intake (g) of all lunch items was measured. The children provided their hedonic rating of the food, a preference ranking and a saltiness ranking in the laboratory. Children could rank the foods according to salt content, and they preferred the two saltier options. A food-specific effect of salt content on intake was observed. Compared to the intermediate level (0.6 g salt/100 g), not adding salt decreased green bean intake (−21%; p = 0.002), and increasing the salt content increased pasta intake (+24%; p<0.0001). Structural Equation Modeling was used to model the relative weights of the determinants of intake. It showed that the primary driver of food intake was the child''s hunger; the second most important factor was the child''s hedonic rating of the food, regardless of its salt content, and the last factor was the child''s preference for the particular salt content of the food. In conclusion, salt content has a positive and food-specific effect on intake; it impacted food preferences and intake differently in children. Taking into account children''s preferences for salt instead of their intake may lead to excessive added salt.     

Bone tissue engineering using adipose‐derived stem cells and endothelial cells: Effects of the cell ratio

The microvascular endothelial network is essential for bone formation and regeneration. In this context, endothelial cells not only support vascularization but also influence bone physiology via cell contact‐dependent mechanisms. In order to improve vascularization and osteogenesis in tissue engineering applications, several strategies have been developed. One promising approach is the coapplication of endothelial and adipose derived stem cells (ADSCs). In this study, we aimed at investigating the best ratio of human umbilical vein endothelial cells (HUVECs) and osteogenic differentiated ADSCs with regard to proliferation, apoptosis, osteogenesis and angiogenesis. For this purpose, cocultures of ADSCs and HUVECs with ratios of 25%:75%, 50%:50% and 75%:25% were performed. We were able to prove that cocultivation supports proliferation whereas apoptosis was unidirectional decreased in cocultured HUVECs mediated by a p‐BAD‐dependent mechanism. Moreover, coculturing ADSCs and HUVECs stimulated matrix mineralization and the activity of alkaline phosphatase (ALP). Increased gene expression of the proangiogenic markers eNOS, Flt, Ang2 and MMP3 as well as sprouting phenomena in matrigel assays proved the angiogenic potential of the coculture. In summary, coculturing ADSCs and HUVECs stimulates proliferation, cell survival, osteogenesis and angiogenesis particularly in the 50%:50% coculture.     

Camponotus ants mine sand for vertebrate urine to extract nitrogen

The ability of some ant species (including Camponotus spp.) to forage on vertebrate urine to extract urea may extend their niche in competitive and strongly nitrogen‐limited environments. We examined the preference of Camponotus terebrans, a sand‐dwelling ant widespread in southern Australia, for baits including urine, and the duration of their foraging on those baits. We baited ants with liquid stains of urine (human and kangaroo), urea in water (2.5%. 3.5%, 7.0%, 10.0%) and sucrose in water (20% and 40%) poured directly on the ground, as well as hard baits in plots drawn on sandy soil (Kangaroo Island, South Australia). We counted individuals of this mostly nocturnal species to determine their attraction to different baits for one month. We checked plant growth on the plots after nine and 13 months. Ants collected insects and meat; they foraged for at least 29 days on stains. Ants were most numerous on 10% urea, followed by 7% urea, 3.5% urea, urine (which contains ~2.5% urea) and 2.5% urea, 40% sucrose and 20% sucrose; sucrose was less attractive to them than equimolar urea bait. Ants were attracted to human, kangaroo, and unidentified urines, and they collected bird guano. Baits and ant foraging did not affect plant recruitment in plots. We observed incidentally Camponotus consobrinus foraging on urine, which may be a common resource for this genus at the site. The remarkable ability of C. terebrans to extract nitrogen from dry sand over weeks explains partly its success on sandy soils. Foraging on urine may be an important strategy to address nitrogen limitation on sandy soils and exploit commensally niches in which hosts are kangaroos, wallabies and other vertebrates. The understanding of plant–vertebrate interactions must factor in the role of ants as commensal organisms. Such ants could also reduce greenhouse gas emissions from urine.     

The importance of naturally attenuated SARS-CoV-2in the fight against COVID-19

The current SARS-CoV-2 pandemic is wreaking havoc throughout the world and has rapidly become a global health emergency. A central question concerning COVID-19 is why some individuals become sick and others not. Many have pointed already at variation in risk factors between individuals. However, the variable outcome of SARS-CoV-2 infections may, at least in part, be due also to differences between the viral subspecies with which individuals are infected. A more pertinent question is how we are to overcome the current pandemic. A vaccine against SARS-CoV-2 would offer significant relief, although vaccine developers have warned that design, testing and production of vaccines may take a year if not longer. Vaccines are based on a handful of different designs (i), but the earliest vaccines were based on the live, attenuated virus. As has been the case for other viruses during earlier pandemics, SARS-CoV-2 will mutate and may naturally attenuate over time (ii). What makes the current pandemic unique is that, thanks to state-of-the-art nucleic acid sequencing technologies, we can follow in detail how SARS-CoV-2 evolves while it spreads. We argue that knowledge of naturally emerging attenuated SARS-CoV-2 variants across the globe should be of key interest in our fight against the pandemic.