Design and in vitro studies of a needle-type glucose sensor for subcutaneous monitoring

International audienceA new miniaturized glucose oxidase based needle-type glu¬ cose mlcrosensor has been developed for subcutaneous glu¬ cose monitoring. The sensor Is equivalent In shape and size to a 26-gauge needle (0.45-mm o.d.) and can be Implanted with ease without any Incision. The novel configuration greatly facilitates the deposition of enzyme and polymer films so that sensors with characteristics suitable for In vivo use (upper limit of linear range > 15 mM, response time 60%). The sensor response is largely Independent of ox¬ ygen tension In the normal physiological range. It also ex¬ hibits good selectivity against common interferences except for the exogenous drug acetaminophen

Supercoils in human DNA.

The three-dimensional structure of a double-stranded DNA molecule may be described by distinguishing the helical turns of the DNA duplex from any superhelical turns that might be superimposed upon the duplex turns. There are characteristic changes in the hydrodynamic properties of superhelical DNA molecules when they interact with intercalating agents. The hydrodynamic properties of nuclear structures released by gently lysing human cells are changed by intercalating agents in this characteristic manner. The characteristic changes are abolished by irradiating the cells with gamma-rays but may be restored by incubating the cells at 37 degrees C after irradiation. These results are interpreted as showing that human DNA is supercoiled. A model for the structure of the chromosome is suggested

Mapping sequences in loops of nuclear DNA by their progressive detachment from the nuclear cage.

Nuclear DNA is organised into loops, probably by attachment to a supramolecular structure. We describe a method which enables us to map the position of sequences within a loop relative to the point of attachment. Nuclear DNA is isolated unbroken by lysing HeLa cells in 2M NaCl to release structures which retain many of the morphological features of nuclei. Their DNA is supercoiled and so must remain unbroken and looped during lysis. Nucleoids are digested to various degrees with a restriction endonuclease and the cages - and any associated DNA - sedimented free from unattached DNA. The cage-associated DNA is purified and completely fragmented using the same restriction endonuclease. Equal weights of fragmented DNA are separated by gel electrophoresis, transferred to a filter and the relative amounts of the alpha, beta and gamma globin genes on the filter determined by hybridisation to the appropriate probes. The alpha genes, unlike the beta and gamma genes, resist detachment from the cage and so must lie close to the point of attachment to the cage. Our ability to map these genes implies that sequences cannot be attached at random to the cage; rather, specific sequences must be attached, so looping the DNA

Bayesian Analysis of Hierarchical Effects

The idea of hierarchical, sequential, or intermediate effects has long been posited in textbooks and academic literature. Hierarchical effects occur when relationships among variables are mediated through other variables. Challenges in studying hierarchical effects in marketing include the large number of items present in most commercial studies and the presence of heterogeneous relationships among the variables. Existing approaches have dealt with the large number of variables by employing a factor structure representation of the data and have used standard mixture distributions for representing different response segments. In this paper, we propose a Bayesian model for the analysis of hierarchical data using the actual response items and incorporating heterogeneity that better reflects consumer stages in a decision process. Cross-sectional data from a national brand-tracking study are used to illustrate our model, where we find empirical support for a hierarchical relationship among media recall, brand beliefs, and intended actions. We find these effects to be insignificant when measured with standard models and aggregate analyses. The proposed model is useful for understanding the influence of variables that lead to intermediate as opposed to direct effects on brand choice.hierarchical Bayes, mediation analysis, structural heterogeneity, variable selection