Recurrent environmental contamination in a centralized radiopharmacy unit by Achromobacter spp: results of a large microbiological investigation

BACKGROUND

Radiopharmaceuticals preparation unit, such as every aseptic preparation units, are strictly monitored in terms of microbiological contamination. Despite all biocontamination control procedures, our radiopharmacy unit faced repeated environnmental contamination by Achromobacter spp which necessitated a large environmental investigation.

METHOD

Microbiological controls were carried out using Count Tact agars (Biomérieux) for flat surfaces, dry swabbing for hard to reach areas and containers were filled with a sterile water solution (then filtrated on 0.45µm membrane and seeded). Microbiological identification was performed by mass spectrometry (MALDI-TOF-MS, Brucker) on each positive sample.

RESULTS

Achromobacter spp was found in 10% of the 413 samples during the 8 months investigation period. The proportion of positive samples was stable among time but their location was unpredictable. The highest inoculum was finally found in the buckets used for biocleaning.

DISCUSSION

Samples from cleaning buckets taken by dry swabbing were at first negative, but the use of a non-routinely used sampling method allowed to discover the reservoir of this persistent contamination.

CONCLUSION

This investigation alerted us on the high microbiological risk associated with reusable plastic containers and the importance of a sampling method adapted to critical locations.

An Information System for Epidemiology based on a Computer-Based Medical Record

A new way is presented to build an information system addressed to problems in epidemiology. Based on our analysis of current and future requirements, a system is proposed which allows for collection, organization and distribution of data within a computer network. In this application, two broad communities of users – physicians and epidemiologists – can be identified, each with their own perspectives and goals. The different requirements of each community lead us to a client-service centered architecture which provides the functionality requirements of the two groups. The resulting physician workstation provides help for recording and querying medical information about patients and from a pharmacological database. All information is classified and coded in order to be retrieved for pharmaco-economic studies. The service center receives information from physician workstations and permits organizations that are in charge of statistical studies to work with “real” data recorded during patient encounters. This leads to a new approach in epidemiology. Studies can be carried out with a more efficient data acquisition. For modelling the information system, we use an object-oriented approach. We have observed that the object-oriented representation, particularly its concepts of generalization, aggregation and encapsulation, are very usable for our problem.

The Rhône-Alpes Health Platform

Objectives: The purpose of this workis to develop a health information platform connecting most health facilities in the Rhône-Alpes region. The health platform called SIS-RA is used through a Web interface. An iconic interface is dedicated to the platform and presents information in a unique way for all users.

Methods: Newtechniques have been used to develop this platform which will be used by a great number of Rhône-Alpes doctors in the future. We chose a user-centered design which takes into account doctors’ requirements (hospital and GP). We also consider that no system has to be rebuilt, but a direct connection to the legacysystems should be provided.

Results: The platform permits fast and more appropriate medical decisions than those made without this information system. The iconic interface presents all medical documents in a uniform way. Currently, 11 healthcare facilities and 15 community health networks are connected to SIS-RA sharing more than 60,000 records with 1.2 million indexed items. 3200 doctors use the system.

Conclusion: The platform is approved by French supervision authorities (regional hospitals association (ARH)), regional practitioners union (URML) and Rhônes-Alpes region administration and is known as the official shared health record.

Quantification of depletion-induced adhesion of red blood cells

Red blood cells (RBCs) are known to form aggregates in the form of rouleaux due to the presence of plasma proteins under physiological conditions. The formation of rouleaux can also be induced in vitro by the addition of macromolecules to the RBC suspension. Current data on the adhesion strength between red blood cells in their natural discocyte shapes mostly originate from indirect measurements such as flow chamber experiments, but data is lacking at the single cell level. Here, we present measurements on the dextran-induced aggregation of red blood cells using atomic force microscopy-based single cell force spectroscopy. The effects of dextran concentration and molecular weight on the interaction energy of adhering RBCs were determined. The results on adhesion energy are in excellent agreement with a model based on the depletion effect and previous experimental studies. Furthermore, our method allowed to determine the adhesion force, a quantity that is needed in theoretical investigations on blood flow.

Traction patterns of tumor cells

The traction exerted by a cell on a planar deformable substrate can be indirectly obtained on the basis of the displacement field of the underlying layer. The usual methodology used to address this inverse problem is based on the exploitation of the Green tensor of the linear elasticity problem in a half space (Boussinesq problem), coupled with a minimization algorithm under force penalization. A possible alternative strategy is to exploit an adjoint equation, obtained on the basis of a suitable minimization requirement. The resulting system of coupled elliptic partial differential equations is applied here to determine the force field per unit surface generated by T24 tumor cells on a polyacrylamide substrate. The shear stress obtained by numerical integration provides quantitative insight of the traction field and is a promising tool to investigate the spatial pattern of force per unit surface generated in cell motion, particularly in the case of such cancer cells.

Fractal approach to the rheology of concentrated cell suspensions

Results on the rheological behavior of Chinese hamster ovary cell suspensions in a large range of concentrations are reported. The concentration-dependent yield stress and elastic plateau modulus are formalized in the context of fractal aggregates under shear, and quite different exponents are found as compared to the case of red blood cell suspensions. This is explained in terms of intrinsic microscopic parameters such as the cell-cell adhesion energy and cell elasticity but also the cell's individual dynamic properties, found to correlate well with viscoelastic data at large concentrations (phi>or=0.5).

Modeling breakup and relaxation of Newtonian droplets using the advected phase-field approach

The relaxation and breakup of Newtonian droplets is considered using the advected field approach. This method allows one to follow the deformation of interfaces using an order parameter field [Biben, Europhys. Lett. 63, 623 (2003)] based on a Ginzburg-Landau equation. Using this method, it is possible to follow the breakup of droplets and stability curves can be obtained in both two- and three-dimensional shear and elongational flows. Finally, relaxation of a droplet is considered, following the application of an elongational flow. The results are compared with previous experimental data [Ha and Leal, Phys. Fluids 13, 1568 (2001)], and are found to be in satisfactory agreement. The method is general enough to be applied to other non-Newtonian fluids, such as Oldroyd-B fluids or viscoplastic materials.

The Rhône-Alpes health platform

OBJECTIVES

The purpose of this work is to develop a health information platform connecting most health facilities in the Rhône-Alpes region. The health platform called SIS-RA is used through a Web interface. An iconic interface is dedicated to the platform and presents information in a unique way for all users.

METHODS

New techniques have been used to develop this platform which will be used by a great number of Rhône-Alpes doctors in the future. We chose a usercentered design which takes into account doctors' requirements (hospital and GP). We also consider that no system has to be rebuilt, but a direct connection to the legacy systems should be provided.

RESULTS

The platform permits fast and more appropriate medical decisions than those made without this information system. The iconic interface presents all medical documents in a uniform way. Currently, 11 healthcare facilities and 15 community health networks are connected to SIS-RA sharing more than 60,000 records with 1.2 million indexed items. 3200 doctors use the system.

CONCLUSION

The platform is approved by French supervision authorities (regional hospitals association (ARH)), regional practitioners union (URML) and Rhônes-Alpes region administration and is known as the official shared health record.

Elongation and burst of axisymmetric viscoelastic droplets: a numerical study

The dynamics of elongation and burst of an isolated viscoelastic drop are investigated numerically in the special case of a viscosity ratio lambda = 1 . We show that the burst threshold is not affected by viscoelasticity itself, whereas the stationary drop morphology is. A dimple at the tips of the drop can even be observed when elastic effects are large. The burst dynamics is very sensitive to the presence of viscoelasticity: at low elasticity burst is slowed down while for large elasticity levels it becomes even faster than the Newtonian situation.

Rheological Properties of Living Materials. From Cells to Tissues

In this paper, we review the role of the rheological properties at the cellular and macroscopic scale. At the cellular scale, the different components of the cell are described, and comparisons with other similar systems are made in order to state what kind of rheological properties and what constitutive equations can be expected. This is based on expertise collected over many years, dealing with components such as polymers, suspensions, colloids and gels. Various references are considered. Then we review the various methods available in the literature, which can allow one to go from the microscopic to the macroscopic properties of an ensemble of cells, in other words a tissue. One of the questions raised is: can we find different properties at the macroscopic level than the ones that we start with at the cellular level? Finally, we consider different biological materials which have been used and characterized, in order to classify them. Constitutive laws are also proposed and criticized. The most difficult part of modeling is taking into account the active part of cells, which are not just plain materials, but are living objects.

Characterization of wheat-flour-water doughs: a new method using ultrasound

In this paper, an original method of evaluating the physical properties of wheat-flour-water systems using high-frequency low-power ultrasound is presented. Most of the experiments were performed with a reflectance technique measuring the acoustic impedance of doughs. The velocity of propagation, attenuation and viscoelastic moduli have been evaluated for both compressional and shear ultrasonic waves in the interval 2-10 MHz for doughs of different hydrations. The 53% water content was found to be critical with respect to the presence of free water. The influence of the mixing and rest times on the longitudinal ultrasonic parameters is also studied.

[Proposals for a system of managing medical information]

Various systems are being used for managing medical information. They have several shortcomings. Among these, one can quote: -they do not overcome the complex medical terminology and its diversity; -they do not use a common medical language -there is no easy communication between the softwares used -and so on The proposed system takes into account the multiplicity of information sources within a hospital and the need for individual decision-making from care providers.

An information system for epidemiology based on a computer-based medical record

A new way is presented to build an information system addressed to problems in epidemiology. Based on our analysis of current and future requirements, a system is proposed which allows for collection, organization and distribution of data within a computer network. In this application, two broad communities of users-physicians and epidemiologists-can be identified, each with their own perspectives and goals. The different requirements of each community lead us to a client-service centered architecture which provides the functionality requirements of the two groups. The resulting physician workstation provides help for recording and querying medical information about patients and from a pharmacological database. All information is classified and coded in order to be retrieved for pharmaco-economic studies. The service center receives information from physician workstations and permits organizations that are in charge of statistical studies to work with "real" data recorded during patient encounters. This leads to a new approach in epidemiology. Studies can be carried out with a more efficient data acquisition. For modelling the information system, we use an object-oriented approach. We have observed that the object-oriented representation, particularly its concepts of generalization, aggregation and encapsulation, are very usable for our problem.