A novel fluorescence-based array biosensor: principle and application to DNA hybridization assays.

A novel fluorescence-based array biosensor targeted for field applications, such as environmental monitoring, has been developed, and successfully applied to DNA hybridization assays. The purpose was to meet the demand for automated, portable but easy-to-maintain systems allowing continuous flow monitoring of surface reactions. The biosensor presented here can be distinguished from the existing systems by the optical method used, which provides an enhanced simplicity and robustness, and enables a simple maintenance by potentially unskilled personnel.

Characterization and optimization of a real-time, parallel, label-free, polypyrrole-based DNA sensor by surface plasmon resonance imaging.

We describe in this paper a methodology to quantify multispot parallel DNA hybridizations and denaturations on gold surfaces by using, on one hand, a polypyrrole-based surface functionalization based on an electrospotting process and, on the other hand, surface plasmon resonance imaging allowing real-time measurements on several DNA spots at a time. Two characterization steps were performed in order to optimize the immobilization of oligonucleotide probes and, thus, to increase the signal-to-noise ratio of monitored hybridization signals: the first step consisted of characterizing the signal dependence upon the density of immobilized 15-mer probes, and, the second step, in analyzing the hybridization response versus spot thickness. We further demonstrated that a surface density of polypyrrole/DNA probes of approximately 130 fmol/ mm2 (590 pg/mm2) optimizes the hybridization signal that can be detected directly.

[Gastroduodenal ulcers in young adults. An epidemiological study (author's transl)].

An epidemiological survey of gastroduodenal ulcers was carried ut in an homogenous population of 100000 young adults of National Service age, and the results were compared with those of a similar survey which had taken place 6 years previously. Between 1971 and 1977 the overall incidence of gastroduodenal ulcers had risen from 1,57 to 2.14 p.

[Production of interferon and alpha 2-macroglobulin involvement in immune response during human viral hepatitis A (author's transl)].

In viral hepatitis A, we could distinguish between monophasic and polyphasic forms. Monophasic and polyphasic hepatitis A induce the production of plasma interferon. Interferon level, elevated as early as the first days following the appearance of clinical signs, decreases and reaches a minimum value on the seventh day.