Biomedical subjects
G Reid
Publications and source records attributed to G Reid.
Differentiation of Lactobacillus Species by Molecular Typing.
A total of 64 type, reference, clinical, health food, and stock isolates of microaerophilic Lactobacillus species were examined by restriction fragment length polymorphisms. Of particular interest were members of six of the eight species most commonly recovered from the vaginas of healthy premenopausal women, namely, Lactobacillus jensenii, L. casei, L. rhamnosus, L. acidophilus, L. plantarum, and L. fermentum. Six main groupings were identified on the basis of ribotyping. This technique was able to classify fresh isolates to the species level. In the case of the ribotype A grouping for L. rhamnosus, differences between strains were evident by chromosome typing (chromotyping). Many isolates did not possess plasmids. Six L. rhamnosus strains isolated from four different health food products appeared to be identical to L. rhamnosus ATCC 21052. The molecular typing system is useful for identifying and differentiating Lactobacillus isolates. Studies of strains of potential importance to the urogenital flora should include molecular characterization as a means of comparing genetic traits with those of strains whose characteristics associated with colonization and antagonism against pathogens have been defined.
Surrogate antigen processing mediated by TAP-dependent antigenic peptide secretion.
MHC class I proteins assemble with peptides in the ER. The peptides are predominantly generated from cytoplasmic proteins, probably by the action of the proteasome, a multicatalytic proteinase complex. Peptides are translocated into the ER by the transporters associated with antigen processing (TAP), and bind to the MHC class I molecules before transport to the cell surface. Here, we use a new functional assay to demonstrate that peptides derived from vesicular stomatitis virus nucleoprotein (VSV-N) antigen are actively secreted from cells. This secretion pathway is dependent on the expression of TAP transporters, but is independent of the MHC genotype of the donor cells. Furthermore, the expression and transport of MHC class I molecules is not required. This novel pathway is sensitive to the protein secretion inhibitors brefeldin A (BFA) and a temperature block at 21 degrees C, and is also inhibited by the metabolic poison, azide, and the protein synthesis inhibitor, emetine. These data support the existence of a novel form of peptide secretion that uses the TAP transporters, as opposed to the ER translocon, to gain access to the secretion pathway. Finally, we suggest that this release of peptides in the vicinity of uninfected cells, which we term surrogate antigen processing, could contribute to various immune and secretory phenomena.
XPS and SEM detection of surface changes on 64 ureteral stents after human usage.
Ureteral stents are commonly implanted to assist the postsurgery flow of urine from the kidney to the bladder. We hypothesized that different surface compositions of stent material could result in different conditioning film depositions and potentially altered receptivity to bacterial biofilms. Using XPS, three types of ureteral stents recovered from 64 patients were found to have adsorbed conditioning films that altered the surface composition of the devices. Elements associated with encrustation (calcium, magnesium and phosphorus) were found on 69% of the silicone latex stents, 44% of the low surface energy (LSe) devices, and 38% of the carbon-rich stents. No statistical difference was found in relation to patient gender, stent type, duration of implantation, and encrustation deposition. The composition of the film suggested that the nature of the underlying material did not significantly alter the elements that adsorbed. Thus, devices may take on a similar surface coat within days, and perhaps hours, of exposure to the host. With respect to dense encrustations, fewer appeared on the LSe devices. SEM confirmed the presence and nature of the film crystals and showed bacterial biofilms adherent to devices and encrustations in three patients who had received prophylactic trimethoprim compared to one on ciprofloxacin. In conclusion, although encrustation deposition and biofilm formation on ureteral stents is not unique to Cook devices, the human model and surface science test systems described here are invaluable to evaluate biomaterials used in patients. Unless biomaterials undergo rigorous analysis in vivo, including true assessment of the outcome of prophylactic antibiotic usage, clinicians will be unable to accurately select the best device and management strategy for a given patient.
Conditioning film deposition on ureteral stents after implantation.
Three types of ureteral stents were used in a study of 53 patients. Following extracorporeal shock wave lithotripsy, the stents were implanted and retained for periods of between 3 and 40 days. Each patient received daily antibiotic therapy with either ciprofloxacin or trimethoprim. After removal, the devices were analyzed for adherent bacteria and encrustations. The study showed that a conditioning film became deposited onto the stents upon implantation, changing the surface characteristics of the biomaterials. Dense encrustations were found to be least on a low surface energy device. No differences were found related to patient age and gender or duration of stent insertion. Flakiness and apparent sloughing of the stent surfaces was observed in some devices, raising concerns as to what actually happens to medical devices when exposed to the host urinary tract. Bacteria were recovered from the urine of three patients and the stents of four patients treated with trimethoprim. Five stents had bacterial biofilms detected by SEM. The actual clinical end-point was not the focus of this study, but no patients became septic. Our goal was to demonstrate conclusively in humans that medical devices do develop conditioning films upon implantation, and that they can be susceptible to bacterial colonization even during antibiotic treatments. The kidneys of stented patients are clearly at risk of infection, and only by proper selection of a stent type and appropriate antibiotic coverage can this risk be significantly reduced.
Bacterial biofilm formation, encrustation, and antibiotic adsorption to ureteral stents indwelling in humans.
Encrustation and urinary tract infection are problematic complications of ureteral stent usage. The objective of our first study was to use surface science techniques to examine three ureteral stent types for encrustation, biofilm formation, and antibiotic adsorption after use in patients. Black Beauty (N = 16), LSe (N = 16), and SofFlex (N = 32) ureteral stents were recovered from patients who had received trimethoprim or ciprofloxacin while the stent was indwelling. These stents were examined with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDX) for the presence and composition of encrustation or biofilm. Conditioning films and encrustations were found on all stents. Encrustation elements (Ca, Mg, P) were identified on 11 of 16 Black Beauty (69%), 7 of 16 LSe (44%), and 12 of 32 SofFlex (38%) stents. The stent type, duration of insertion, and age or sex of the patient did not correlate significantly with the amount of encrustation. Bacterial biofilms were found on 1 of 7 Black Beauty stents (14%) and 7 of 32 SofFlex stents (22%). In a second study, an additional 28 patients with SofFlex stents were treated with ciprofloxacin (N = 16) or ofloxacin (N = 12). Their stents were subjected to high-performance liquid chromatography to determine if oral antibiotic therapy can lead to drug adsorption to the stent. Analysis showed that both ciprofloxacin and ofloxacin adsorbed to the stent surfaces. The mean concentrations of the two antibiotics within the conditioning film of the stents were 0.99 microg/mL and 0.34 microg/mL, respectively. These surface science techniques provide a comprehensive method of evaluating ureteral stents and other prosthetic devices in vivo.
Biomaterials used in urology: current issues of biocompatibility, infection, and encrustation.
This review focuses on the biomaterials used in urology, in particular, the properties of urethral catheters and ureteral stents currently being used in clinical practice. The importance of biomaterial type, biocompatibility, and encrustations are discussed and explained. Current management of bacterial infection and the importance of biofilms are presented, with recommendations based on published information.
Interference in initial adhesion of uropathogenic bacteria and yeasts to silicone rubber by a Lactobacillus acidophilus biosurfactant.
The ability of the Lactobacillus acidophilus RC14 biosurfactant 'surlactin' to inhibit the initial adhesion of various uropathogenic bacteria and two yeast strains to silicone rubber was investigated in a parallel-plate flow chamber in filter-sterilised pooled human urine. A parallel-plate flow chamber with a silicone rubber bottom plate was filled with a 1.0 mg/ml biosurfactant solution for adsorption overnight (18 h). Subsequently, the adhesion of the bacterial or yeast cells from a urine suspension under low flow (shear rate 15 s(-1)) was followed in situ by automated image analysis. Control tests were with untreated silicone rubber. Initial deposition rates and numbers of adhering cells after 4 h of flow were determined. Surlactin layers caused a marked inhibition of the initial deposition rates and adhesion numbers after 4 h for the majority of the bacteria (11 of 15 strains tested) and this inhibition was particularly effective against Enterococcus faecalis, Escherichia coli and Staphylococcus epidermidis. Although the initial deposition rates of the two Candida albicans strains were reduced by c. 50% in comparison with the controls, the numbers of yeast cells adhering after 4 h were similar.
A methodology for sampling and accessing homeless individuals in Melbourne, 1995-96.
A methodology for sampling homeless populations in inner Melbourne was developed to study their health status and prevalence of tuberculosis. This paper describes the design, development and implementation of the project. The results of health status and tuberculosis analysis are published elsewhere. Involvement and interaction with local service providers and agencies to homeless people was central to the project throughout. A definitional construct of homelessness was developed, drawn from local and overseas literature and contemporary local experience. The study's aim was to obtain a representative sample of homeless individuals in various levels of accommodation and a convenience sample of those who were unaccommodated (streets and parks). A comprehensive sampling frame of accommodation options was constructed from available databases, and systematic sampling applied to produce a sample of 396 beds, from which 284 participants were enrolled. Convenience sampling of unaccommodated homeless individuals produced 100 participants. All agreed to undergo a comprehensive questionnaire, blood and Mantoux testing, the latter being completed successfully in 94%. Commonsense, cultural sensitivity and a non-threatening approach were critical to the success of the project and the security of the field workers. The methods described attempt to address recognised difficulties of sampling from homeless populations and should be reproducible both in the future and elsewhere. Potential for selection bias remains the main threat to validity, which the described methodology combined with adequate resources should help to address.
Effect of nutrient composition on the in vitro growth of urogenital lactobacilli and uropathogens.
Previous clinical studies have shown that nutrients and probiotic agents can alter the composition of the vaginal flora. The present in vitro study has shown that uropathogens have a growth advantage over lactobacilli, but potentially there are natural substances that could be applied vaginally to stimulate lactobacilli growth to the detriment of the pathogens. When chemically defined medium representative of vaginal fluid at pH 5.5 was supplemented with skim milk, it acted as a better substrate for Lactobacillus rhamnosus GR-1 than for uropathogenic bacteria and Candida albicans. Lactobacillus MRS medium, even at pH 4.5, supports the growth of pathogens, but when supplemented with ascorbic acid or EDTA, Lactobacillus growth was significantly higher. When L. rhamnosus GR-1 was coincubated in a combined nutrient composition of vitamins and lactose, it survived better than Escherichia coli and Enterococcus faecalis. These in vitro results provide a basis for testing nutritional supplements to alter the urogenital flora in an attempt to enhance restoration and maintenance of a normal disease-free state.
Cloning of a human renal p-aminohippurate transporter, hROAT1.
Explore the source record for details and available documents.
Engaging the faculty: a university science professor recommends getting his colleagues in deep with fund-raising programs.
Explore the source record for details and available documents.
Bacterial colonization of prosthetic devices and measures to prevent infection.
Prosthetic devices are used extensively in surgical practice. This includes devices used on a temporary, intermittent, and long-term basis. In addition to problems with biocompatibility, the main health care issue concerning prostheses is the elevated risk of infection and the current inability to effectively prevent and treat such infections. An appreciation of microbial biofilm development has drawn attention to flaws in diagnosis and led to new methods to attack the problem. Future remedies will likely involve utilization of new biomaterial designs and application of either highly potent antimicrobials or agents used in combination that penetrate biofilms and eradicate the organisms.
Injecting drug use and HIV infection in Asia. The Asian Harm Reduction Network.
Explore the source record for details and available documents.
Novel peptide-binding proteins and peptide transport in normal and TAP-deficient microsomes.
Most major histocompatibility complex (MHC) class I-binding peptides are translocated by TAP heterodimers, but some enter the ER lumen by alternative pathways. To further define mechanisms of peptide handling, we developed a system for the analysis of peptide-binding components in the ER membrane and lumen using iodinated cross-linkable peptide derivatives. Here we demonstrate that at least three proteins bind peptides in the ER lumen. Peptide cross-linking to these lumenal proteins can be used as an alternative method to monitor peptide transport. TAP and one other protein bind peptides on the cytoplasmic face of the ER. The presence of multiple peptide-binding proteins necessitates caution in interpreting traditional peptide-binding and transport assays. Finally, we demonstrate sequence-specific peptide transport in TAP-deficient cells transfected with only rat TAP1.
Inhibition of initial adhesion of uropathogenic Enterococcus faecalis to solid substrata by an adsorbed biosurfactant layer from Lactobacillus acidophilus.
OBJECTIVES: The potency of the Lactobacillus acidophilus RC14 biosurfactant "surlactin" to reduce the initial adhesion of Enterococcus faecalis 1131 was investigated on a hydrophilic and a hydrophobic substratum in a parallel-plate flow chamber, using phosphate-buffered saline and pooled human urine as a suspending fluid. METHODS: A parallel-plate flow chamber with a glass or silicone rubber bottom plate was filled with different biosurfactant solutions of 0, 0.01, 0.1, or 1.0 mg/mL for overnight adsorption (18 hours). Subsequently, the adhesion of E. faecalis on thus prepared biosurfactant layers was observed in situ in phosphate-buffered saline or in urine by automated image analysis. RESULTS: Adsorbed biosurfactant layers caused an important, dose-related inhibition of the initial deposition rate of E. faecalis and the number of adherent bacteria after 4 hours on both hydrophilic glass and hydrophobic silicone rubber, although this effect was stronger in buffer than in urine. For the experiments carried out in urine, the inhibitory effect of the biosurfactant layer was largest when silicone rubber was used rather than glass, whereas no influence of the substratum hydrophobicity on the inhibition of E. faecalis adhesion was noticed for experiments performed in buffer. CONCLUSIONS: The biosurfactant surlactin, as released by several Lactobacillus isolates, might open the way to the development of antiadhesive biologic coatings for catheter materials. It should be considered, however, that these results are preliminary and that the efficiency of the biosurfactant is probably affected not only by the hydrophobicity of the substratum and the suspending fluid, but also by the type of uropathogen involved.
Adhesion of Lactobacillus species in urine and phosphate buffer to silicone rubber and glass under flow.
Coating uroepithelial cells or catheter materials with lactobacilli has been shown to retard the development of a uropathogenic biofilm, with biosurfactant production and strong adhesion being two prerequisite properties of the Lactobacillus strains to be employed. In this paper, adhesion of six selected Lactobacillus strains to silicone rubber and glass in urine and in a phosphate buffer was studied using a parallel plate flow chamber. In addition, adhesive cell surface properties of the lactobacilli, i.e. the pH dependences of their zeta potentials and their hydrophobicities by water contact angles, were determined. L. acidophilus ATCC 4356 and L. fermentum B54 were the only strains showing significant adhesion to both hydrophobic silicone rubber and hydrophilic glass, possibly by virtue of their high cell surface hydrophobicities (water contact angles of 68 and 75 degrees, respectively) and small zeta potentials (-10.0 and -8.1 mV in buffer, respectively). Both hydrophobic Lactobacillus strains adhered less well in urine than in buffer. The remaining Lactobacillus strains studied were hydrophilic, with water contact angles between 25 and 36 degrees, and had highly negative zeta potentials, reaching -37.7 mV in buffer. Adhesion of these highly negatively charged, hydrophilic strains in buffer was essentially absent, while for some of these strains minor adhesion in urine was observed. This study demonstrates that the adhesion of lactobacilli to substrata differs with strain hydrophobicity and charge, and that urinary components can affect the ability of hydrophilic Lactobacillus strains to adhere to substrata.
Fostering children's resilience.
Resilience is relevant to nurses because of its implications for health. Research on the resilience of children and adolescents has proliferated over the past five years. However, the specific processes underlying resilience and outcome variables require further study. Furthermore, few intervention studies have been conducted. This article describes resilience and factors that influence resilience of children, examines the relationship between resilience and health, identifies interventions that foster children's resilience and health, reviews research focusing on children's resilience, and suggests the relevance of resilience to nursing of children.