Commensal interactions in a dual-species biofilm exposed to mixed organic compounds.

There is limited knowledge of interspecies interactions in biofilm communities. In this study, Pseudomonas sp. strain GJ1, a 2-chloroethanol (2-CE)-degrading organism, and Pseudomonas putida DMP1, a p-cresol-degrading organism, produced distinct biofilms in response to model mixed waste streams composed of 2-CE and various p-cresol concentrations. The two organisms maintained a commensal relationship, with DMP1 mitigating the inhibitory effects of p-cresol on GJ1. A triple-labeling technique compatible with confocal microscopy was used to investigate the influence of toxicant concentrations on biofilm morphology, species distribution, and exopolysaccharide production. Single-species biofilms of GJ1 shifted from loosely associated cell clusters connected by exopolysaccharide to densely packed structures as the p-cresol concentrations increased, and biofilm formation was severely inhibited at high p-cresol concentrations. In contrast, GJ1 was abundant when associated with DMP1 in a dual-species biofilm at all p-cresol concentrations, although at high p-cresol concentrations it was present only in regions of the biofilm where it was surrounded by DMP1. Evidence in support of a commensal relationship between DMP1 and GJ1 was obtained by comparing GJ1-DMP1 biofilms with dual-species biofilms containing GJ1 and Escherichia coli ATCC 33456, an adhesive strain that does not mineralize p-cresol. Additionally, the data indicated that only tower-like cell structures in the GJ1-DMP1 biofilm produced exopolysaccharide, in contrast to the uniform distribution of EPS in the single-species GJ1 biofilm.

Microelectromechanical systems technology to deliver insulin.

A new microfabrication technology, microelectromechanical systems (MEMS), is envisioned for improved insulin delivery in the context of a device currently being developed for the Defense Advanced Research Projects Agency (DARPA). The drug delivery system utilizes MEMS technology to move and control fluids at the microscale, making possible the reconstitution and delivery of extremely small amounts of drug with extreme precision. In this article, the required microscale components that are currently being developed for the system are described. MEMS are made using fabrication methods similar to that utilized in microelectronics. Consequently, MEMS technology can be used to fabricate devices that are extremely small. The fundamental difference is that MEMS devices can either move themselves or control the movement of other materials, such as fluids. Furthermore, this manufacturing method is intrinsically low-cost and therefore is ideal for drug delivery systems. The current development of a new drug delivery system for controlled drug reconstitution and delivery system for DARPA is described as are the MEMS-based components for the required fluidic control. The adaptation of the system for insulin delivery is addressed and is envisioned to be a fully self-contained parenteral drug delivery system about the size of a 4-mm thick credit card.

Effects of adjacent surfaces of different shapes on regurgitant jet sizes: an in vitro study using color Doppler imaging and laser-illuminated dye visualization.

OBJECTIVES: The present study was designed to estimate the influence of different-shaped adjacent surfaces on regurgitant jets as assessed by color Doppler imaging and laser-illuminated dye optical visualization. BACKGROUND: Because color Doppler techniques provide real-time two-dimensional imaging of flow, the evaluation of valvular regurgitation by analysis of variance-encoded regurgitant jets by this method has been widely used in clinical studies. However, recent studies have demonstrated that color Doppler jet sizes are affected not only by several hemodynamic factors and instrument settings but also by the interaction between jets and adjacent wall surfaces. In clinical conditions, jets may interact with adjacent walls of variable shapes that might have different effects on the jet size. METHODS: An in vitro model was constructed consisting of a rigid, optically clear receiving chamber that had no outlet resistance and had a pulsatile pump ejecting through 1.5, 2.3 and 3.1 mm2 inflow orifices into the chamber. The surfaces were flat or smoothly and equally curved, convex and concave aluminum positioned at 0, 2 and 4 mm from and to the side of the inflow orifices. The pump was run with stroke volumes from 0.5 to 3.0 ml and with a pulse frequency of 70 beats/min. The echocardiographic and laser beams were aimed at the inflow orifice imaging jets perpendicular to the surfaces (vertical view) through the central plane of the jet flows. Maximal jet areas were measured by both color Doppler techniques and laser-illuminated dye visualization. RESULTS: Color Doppler study showed fair correlation between the jet areas and the stroke volumes (r = 0.83 to 0.99), but the jet sizes under different surface conditions were variable. All the surface jet areas at a jet-surface distance of 0 and 2 mm were smaller than free jet areas at the same stroke volume for both flat and convex surfaces (p < 0.001). Flow constraint by the concave surface resulted in the smallest jet areas (p < 0.001). The color Doppler jet areas on the curved surfaces were significantly smaller than the laser-illuminated dye visualization jet areas (p < 0.01 to 0.0001). However, at intermediate jet-surface distances (4 mm and sometimes 2 mm with higher velocity flows), jet interaction with the flat and especially with the convex surface resulted in larger jets. This effect was most pronounced on dye fluorescence studies because flow around these jets consisted mainly of low velocity vortical events with only partial surface adherence and these low velocity swirling flows were not well imaged by color Doppler technique. CONCLUSIONS: Our study suggests that the different-shaped adjacent surfaces with different degrees of flow alterations resulted in variable decreases in jet size and that color Doppler imaging could not encode and image the angled and low velocity swirling events well when jets flowed along the curved surfaces. These effects need to be taken into account when interpreting color Doppler images.

[Development of a questionnaire for problem solving]. / Entwicklung eines Fragebogens zum Problemlösen (PLF).

Presented is the development of a measuring instrument in order to assess the problem solving ability (PLF). The PLF consists of 5 scales: a) experiencing problems, b) problem denial, c) tendency to solve problems in an unconventional way, d) dealing with the problem and e) tendency to conservative problem solving. Test-theoretical analyses are reported as well as, in greater detail, studies for test validation on various populations. High covariations can be shown especially for personality factors.

[Relationship between Eysencks personality types and intellectual performance]. / Beziehungen zwischen Eysencks Persönlichkeitstypen und Intelligenzleistungen.

This study tests Eysenck's psychophysiological hypotheses concerning the relationship between intellectual performance and personality type. The data originated from two partial samples with N = 314. The personality types were distinguished with the ENNR-Questionnaire. The intellectual performance was tested using items which are based on Jäger's factor analytic studies. 23 differentially complex items stemed from the main intelligence factors, and separate measures for speed and quality were used to test the hypotheses. The results of all analyses of variancy falsify Eysenck's hypotheses. The "neurotic introverts" showed the worst results in both quality and speed by most of the items, independent of complexity and intelligence factor (chi-square-test of positional frequency). The "stable" and "neurotic extraverts" showed the best results.