Meticillin-resistant Staphylococcus aureus contamination of healthcare workers' uniforms in long-term care facilities.

Meticillin-resistant Staphylococcus aureus (MRSA) and other multiply resistant bacteria are frequently isolated in long-term care facilities (LTCFs). This study evaluated the contamination of staff clothing in three LTCFs. Over 500 samples were taken from uniforms and their pockets and these samples showed a high level of MRSA contamination. Wearing plastic aprons and managing pocket contents improved the contamination rate. Our results highlight the continued importance of hand hygiene, since staff have frequent contact with their uniforms and could potentially contaminate their hands before care.

[Respiratory tract infections in institutions for elderly people: the GROG Géronto-Alsace, strategy of surveillance and alert]. / Infections respiratoires aiguës dans les collectivités de personnes âgées: le GROG Géronto-Alsace, une démarche expérimentale de surveillance et d'alerte.

OBJECTIVE: Outbreaks of respiratory tract infections are common in institutions for elderly people. The objective of our study was the implementation of a network including 11 institutions to determine the frequency of such outbreaks. Using the collected data, criteria and alert levels are defined to assess the level of respiratory tract infections and develop appropriate interventions. METHODOLOGY: Prospective surveillance for respiratory tract infection was conducted in 11 institutions in Alsace for 2 years. Clinical definitions were used to identify the infected residents. For the identification of influenza virus, nasopharyngeal samples using swabs were obtained and rapid tests (immunoassay) were performed. RESULTS: During the surveillance, outbreaks were identified in institutions. The same observations occurred in all institutions at the same time. Alert levels were defined in order to characterize the outbreak period and to improve detection and control of outbreaks of respiratory tract infections. CONCLUSION: Ours findings show the importance of an adequate surveillance and networks improve the impact of such measures.

Assessment of resorbable bioactive material for grafting of critical-size cancellous defects.

Bioactive glasses form a surface apatite layer in vivo that enhances the formation and attachment of bone. Sol-gel Bioglass graft material provides greater nanoscale porosity than bioactive glass (on the order of 50-200 A), greater particle surface area, and improved resorbability, while maintaining bioactivity. This study histologically and biomechanically evaluated, in a rabbit model, bone formed within critical-sized distal femoral cancellous bone defects filled with 45S5 Bioglass particulates, 77S sol-gel Bioglass, or 58S sol-gel Bioglass and compared the bone in these defects with normal, intact, untreated cancellous bone and with unfilled defects at 4, 8, and 12 weeks. All grafted defects had more bone within the area than did unfilled controls (p < 0.05). The percentage of bone within the defect was significantly greater for the 45S5 material than for the 58S or 77S material at 4 and 8 weeks (p < 0.05), yet by 12 weeks equivalent amounts of bone were observed for all materials. By 12 weeks, all grafted defects were equivalent to the normal untreated bone. The resorption of 77S and 58S particles was significantly greater than that of 45S5 particles (p < 0.05). Mechanically, the grafted defects had compressive stiffness equivalent to that of normal bone at 4 and 8 weeks. At 12 weeks, 45S5-grafted defects had significantly greater stiffness (p < 0.05). At 8 and 12 weeks, all grafted defects had significantly greater stiffness than unfilled control defects (p < 0.05). In general, the 45S5-filled defects exhibited greater early bone ingrowth than did those filled with 58S or 77S. However, by 12 weeks, the bone ingrowth in each defect was equivalent to each other and to normal bone. The 58S and 77S materials resorbed faster than the 45S5 materials. Mechanically, the compressive characteristics of all grafted defects were equivalent or greater than those of normal bone at all time points.

Expression of yeast but not human apurinic/apyrimidinic endonuclease renders Chinese hamster cells more resistant to DNA damaging agents.

Abasic sites represent ubiquitous DNA lesions that arise spontaneously or are induced by DNA-damaging agents. They block DNA replication and are considered to be cytotoxic and mutagenic. The key enzymes involved in the repair of abasic sites are apurinic/apyrimidinic (AP) endonucleases which process these lesions in an error-free mechanism. To analyze the role of AP endonuclease in the protection of mammalian cells against DNA damaging agents, we have transfected both the human (APE) and the yeast (APN1) AP endonuclease in Chinese hamster cells and compared the effects of expression of these genes in stable transfectants as to survival of cells and formation of chromosomal aberrations. Although APE was markedly expressed on RNA and protein level, nuclear extracts of human APE transfectants did not show a higher AP endonuclease activity than the parental line and became not more resistant to the cell killing and clastogenic effect of methyl methanesulfonate (MMS) and hydrogen peroxide (H2O2). In contrast, cells transfected with the yeast APN1 gene expressed higher AP endonuclease activity and became clearly more resistant to the cytotoxic and chromosome breakage inducing activity of the agents. The results indicate that the excision repair capacity and correspondingly the mutagen resistance can be elevated by introducing, in mammalian cells, a yeast DNA repair gene and verify that AP sites are both cytotoxic and clastogenic lesions.

Mechanical strength of fracture callus in osteopenic bone at different phases of healing.

OBJECTIVES: To quantify and compare peak bending force and stiffness of fractured femurs during healing of ovariectomized (OVX) and sham-operated (SHAM) rats. DESIGN: Temporal biomechanical animal study. SETTING: Rat femurs were fractured and surgically fixed by a qualified surgeon. The inherent instability of the fixation system employed produced delayed union of the fracture. All biomechanical assessments were performed with servohydraulic test machines (Instron Inc., Canton, MA, U.S.A.; and MTS Corp., Eden Prairie, MN, U.S.A.). INTERVENTION: OVX was performed sixteen weeks before femur fracture, and the effect of OVX on healing fractures was determined. MAIN OUTCOMES: Peak bending force and stiffness of the healing femurs at four, six, and eight weeks after fracture. RESULTS: Peak bending loads of the healing fractured femurs in the OVX and SHAM animals were not significantly different. Peak bending loads for the OVX animals at four and six weeks were significantly lower than the peak load at eight weeks (p < 0.05), whereas no difference was found in the peak load with respect to time for the SHAM animals. Both SHAM and OVX animals had greater bending stiffness of the healing fractured femur after eight weeks of healing than at four weeks (p < 0.05). CONCLUSIONS: OVX is known to reduce cancellous bone mass and strength, but the effect of OVX on healing of fractures in cortical bone is controversial. This study, using a delayed-union model, found no significant differences between OVX and SHAM animals in the breaking strength of healing fractures.

[Immunoassay rapid test for influenza diagnosis in institutions for elderly people: a four-year surveillance with the GROG Géronto-Alsace]. / Tests rapides de surveillance (TRS) de la grippe en établissements accueillant des personnes âgées: évaluation de quatre années d'utilisation dans le cadre du réseau GROG Géronto-Alsace.

OBJECTIVE: Outbreaks of acute respiratory infections (ARI) are common in institutions for elderly people. The objective of our study was the assessment of immunoassay rapid test used for influenza diagnosis in institutions for elderly people. METHODOLOGY: Prospective surveillance for ARI was conducted in 11 institutions in Alsace over a four-year period. Clinical case definitions are used to identify the infected residents. For the identification of influenza virus, nasopharyngeal swabs are obtained and rapid tests (immunoassay) are performed. RESULTS: Influenza virus was identified with immunoassay rapid test. Then, prophylaxis according to the Conseil supérieur d'hygiène publique de France guidelines was implemented. Nevertheless, the use of the rapid test was not frequent in the individual institution and the information recorded at the GROG Géronto-Alsace level could be use to inform the institutions when it is important to perform these rapid tests. CONCLUSION: Ours findings show the value of the rapid test used in the influenza surveillance and how the networks could help to improve their uses.

Quantification methodology for peripheral quantitative computed tomography (PQCT) data using public domain software.

OBJECTIVE: To develop a method for viewing, processing and acquiring 3-dimensional volumetric data from existing ovine spinal peripheral quantitative computed tomography (PQCT) scans of posterior lateral fusion. DESIGN: An image processing development study. BACKGROUND: Existing medical image viewing software can be expensive and difficult to adapt to meet specific research needs. The goals of this study were to produce volume rendering of PQCT scans through processing, masking, and segmentation using public domain software with established source code. METHODS: Raw data files (DICOM format) of 32 PQCT scans from animals receiving spine fusion were obtained. Metal hardware was removed from the images by masks and image segmentation. Calculation of bone macro-architecture volumetric data was performed on right and left sides of spines to quantify fusion volume in normalized segments between transverse processes. RESULTS: Images were acquired and opened. Application of image processing techniques made it possible to remove surgical hardware from original images with minimal loss of original PQCT data. Volumes were calculated and normalized to gray-scale of total bone throughout individual selected segments. CONCLUSION: Using public domain software is a cost effective means to view, process, and manipulate PQCT data. Bone macro-architecture can provide quantitative volumetric contributions to ascertain the role of structure on mechanical function.

A simple and highly efficient fixation method for Chrysochromulina polylepis (Prymnesiophytes) for analytical flow cytometry.

BACKGROUND: To study the fragile Prymnesiophyte species Chrysochromulina polylepis by flow cytometry (FC), we needed an effective fixation method. This method must guarantee a high yield of fixed cells to achieve acceptable measurement times by FC and to allow quick processing of many samples. Moreover, we wanted a method that allows for storage of fixed samples when FC analysis cannot be done immediately. METHODS: Different aldehydes and methanol were tested at different final concentrations. Gravity sedimentation and centrifugation were applied to achieve higher cell concentrations. Storage of fixed samples was tested under different conditions. RESULTS: 0.25% glutaraldehyde (GA) fixation yielded a recovery rate of about 90%. The signals obtained by FC analysis were excellent. It is possible to centrifuge GA-fixed cells and to store them for several weeks. CONCLUSIONS: GA is the fixative of choice for FC analysis of C. polylepis (and possibly other small delicate species) because it yielded highly significant recovery rates and high-quality FC signals. Cells can be centrifuged to increase the cell concentration, thereby achieving short measurement times with FC. The possibility of long-term storage of fixed cells presents an additional advantage if FC analysis cannot be done immediately.

Improved erythrocyte lysis assay in microtitre plates for sensitive detection and efficient measurement of haemolytic compounds from ichthyotoxic algae.

Haemolytic substances produced by ichthyotoxic algae often are unknown in molecular structure or specific mechanism of toxicity. Detection and quantification of such substances are dependent on bioassays, using markers that are sensitive for haemolytic impairment and generation of a recordable response. The erythrocyte lysis assay (ELA) represents an advantageous bioassay in this respect, because the lytic response can be measured photometrically by the amount of released haemoglobin. The aim of the present study was to establish an improved assay based on the ELA principle, for sensitive determination of haemolytic substances of microalgae and for high sample throughput. For this purpose we adapted the ELA to a 96-well microtitre plate format, which significantly reduced the sample volumes and allowed rapid processing of samples. Further improvement was achieved by measuring absorption of lysed erythrocytes at 414 nm, which significantly increased the sensitivity of the ELA compared to the measurements at 540 nm that are usually applied in this type of assay. Using carp (Cyprinus carpio) erythrocytes it was possible to detect haemolysis induced by 4 microg ml(-1) of saponin and as little as two haemolytic Alexandrium tamarense cells. It is suggested that this improved ELA in microtitre plates be used as a low-cost monitoring tool for detection and analysis of potential harmful algae. Furthermore, this ELA can be useful as a sensitive screening system for substances of pharmacological interest, e.g. selectively acting cytolytic antibiotics.

A tissue-like culture system using microstructures: influence of extracellular matrix material on cell adhesion and aggregation.

Special microenvironmental conditions are required to induce and/or maintain specific qualities of differentiated cells. An important parameter is the three-dimensional tissue architecture that cannot be reproduced in conventional monolayer systems. Advanced tissue culture systems will meet many of these demands, but may reach their limits, especially when gradients of specific substances over distinct tissue layers must be established for long-term culture. These limitations may be overcome by incorporating microstructures into tissue-like culture systems. The microstructured cell support presented consists of a flat array of 625 cubic microcontainers with porous bottoms, in which cells can be supplied with specific media from both sides of the tissue layer. Permanent cell lines and primary rat hepatocytes have been used to test the culture system. In order to define reproducible conditions for tissue formation and for cell adherence to the structure, several ECM (extracellular matrix) components were tested for coating of microstructured substrata. The described tissue culture system offers great flexibility in adapting the cell support to specific needs.