Computerized transcutaneous control of a multichannel implantable urinary prosthesis.

In the present paper we describe a personal computer interface of a multichannel implantable urinary prosthesis. This system is composed of two main parts: the first one is internal and consists of an implant using a 4-microns CMOS gate array chip controlling a wide variety of waveforms via eight monopolar channels. The second, an external controller featuring a versatile software, a PCB card plugged in a portable microcomputer, and a radiofrequency-coupled technique. This device is used to transmit the power, the data and the synchronization clock to the implant by a simple binary signal modulating a 20 MHz carrier. We also report the features of implant encapsulation and electrode design and fabrication. In the experimental phase, we studied the effect of early electric stimulation of the bladder during the spinal shock phase in the dog. We present the operative techniques that enabled us to perform chronic electrostimulation of the sacral roots and discuss the results.

Methods of theophylline assay and therapeutic monitoring of this drug.

The purpose of this article is to review various analytical methods of monitoring plasma theophylline. This article was investigated by the "Drug Commission" of SFBC (Société Française de Biologie Clinique). The primary objective is to provide the "know-how", particular for this analysis, which allows the choice between various analytical methods available: immunochemical or physiochemical ones. The techniques described are not necessarily the best, they are approved and tested methods which are the most frequently used in routine practice. The proposed immunochemical methods are: absorption spectroscopy methods: Enzyme ImmunoAssay (EIA), Enzyme Multiplied ImmunoAssay Technique (EMIT); Reflectance spectroscopy method: Apoenzyme Reactivation Immunoassay System (ARIS); Fluorometry spectroscopy method: Substrate Labeled FluoroImmunoAssay (SLFIA); Fluorometry spectroscopy on solid base; Polarization fluorescence spectroscopy ImmunoAssay (FPIA); Turbidimetric measurements: Particle Enhanced Turbidimetric Inhibition ImmunoAssay (PETINIA); Nephelometric measurement: Nephelometric Inhibition ImmunoAssay (NIIA). And the proposed physicochemical methods are: High Performance Liquid Chromatography (HPLC), Gas Chromatography (GC). The second objective is a review of pharmacological properties of theophylline, necessary for a good understanding of therapeutic drug monitoring: intestinal resorption, distribution, metabolism and elimination, drug interactions, dose/response relationship, physiopathological variations and proposed "predictive" "theophylline test". The authors conclude that because of the multiplicity of methodologies used in theophylline therapeutic monitoring the choice of one of them is not easy. The best way to compare different techniques available would be the use of a "reference material" for theophylline monitoring and a quality control network between different clinical pharmacological laboratories.

Multi-strategy and multi-algorithm cochlear prostheses.

Over the past few years, two generations of cochlear implants have been designed and tested by our group. Since the beginning, our goal was to design a system that is completely transparent to sound processing algorithms and stimulation strategies. The first generation micro-stimulator has eight completely independent channels and the second generation one has sixteen. Each of them is mounted on a thick film hybrid circuit together with necessary interfacing components. The electronic circuits are housed in a hermetically sealed titanium case. They are able to deliver monopolar, bipolar, simultaneous or non-simultaneous stimuli on all of their channels. Their electrodes are addressable with all possible combinations. The eight-channel stimulator has already been successfully implanted on volunteer profoundly deaf patients, validating our concepts and our approaches. The second one is endowed with more flexibility and transparency to stimulation algorithms. It offers extended possibilities and more electrodes combinations. In a second version, this one has also been mounted on a thin film hybrid circuit making its size considerably reduced and allowing implanting it in other sites rather than on the temporal bone. The sound processor supporting these systems communicates with internal parts through an inductive link. It is built around a powerful DSP and can be programmed with more than one algorithm at a time. It has been already programmed with all the known strategies and some original ones such as the technique of vector quantization. The latter uses a dictionary of pre-stored stimulation patterns mapped to sound segments. As for programming the systems, this is accomplished by mean of specific user-friendly application software using a window driven completely graphical interface.