An investigation to determine the influence of illumination sources on colour discrimination in normal subjects and smokers

Accurate colour vision testing requires using the correct illumination. With the plethora of 'daylight' lamps available, is there a cost-effective alternative to the discontinued MacBeth Easel lamp? Smoking is a known risk factor for macula degeneration. As the macula is responsible for colour discrimination, any toxin that affects it has the potential to influence colour discrimination. Aims: To find a costeffective light source for colour vision testing. To investigate the effect of smoking on colour discrimination. To explore how deuteranomalous trichromats compare with normal trichromats. Methods: Using the Ishihara colour vision test subjects were classified into the groups: 'Normal/Control', 'Smoker/Test', and 'Case Study' (subjects who failed the screening test and did not smoke). They completed the Farnsworth Munsell 100 Hue test under each of the three light sources: Phillips EcoHalo Twist (tungsten halogen - THL), Kosnic KCF07ALU/GU10-865 (compact fluorescent- CFL), and Deal Guardian Ltd. GU103X2WA4B-60 (light-emitting diode - LED) Results: 42 subjects took part in the study: 18 in the Normal/Control group, 18 in the Smoker/Test group, and 6 in the Case Study group. For the Normal/Control group the total error scores (TESs) were significantly lower with the CFL than with the THL (p = 0.017) as it was for the Case Study group (p = 0.009). No significant differences were found between the Normal/Control group and the Smoker/Test group for each light source. Decision tree analysis found pack years to be a significant variable for TES. Discussion: All three light sources were comparable with previous studies. The CFL provided better colour discrimination than the LED despite them both being 6500 K. Deuteranomalous trichromats showed a greatest deviation than normal trichromats using the LED. Conclusions: The Kosnic KCF07ALU/GU10-865 is a cost-effective alternative for colour vision testing. Smoking appears to have an effect on colour vision, but requires further investigation.

Oxygen tension modulates the cytokine response of oral epithelium to periodontal bacteria

Background: There is an inverse relationship between pocket depth and pocket oxygen tension with deep pockets being associated with anaerobic bacteria. However, little is known about how the host tissues respond to bacteria under differing oxygen tensions within the periodontal pocket. Aim: To investigate the effect of different oxygen tensions upon nuclear factor-kappa B (NF-?B) activation and the inflammatory cytokine response of oral epithelial cells when exposed to nine species of oral bacteria. Materials and Methods: H400 oral epithelial cells were equilibrated at 2%, 10% or 21% oxygen. Cells were stimulated with heat-killed oral bacteria at multiplicity of infection 10:1, Escherichia coli lipopolysaccharide (15 µg/ml) or vehicle control. Interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-a) levels were measured by enzyme-linked immunosorbent assay and NF-?B activation was measured by reporter vector or by immunohistochemical analysis. Results: Tannerella forsythensis, Porphyromonas gingivalis and Prevotella intermedia elicited the greatest epithelial NF-?B activation and cytokine responses. An oxygen-tension-dependent trend in cytokine production was observed with the highest IL-8 and TNF-a production observed at 2% oxygen and lowest at 21% oxygen. Conclusions: These data demonstrate a greater pro-inflammatory host response and cell signalling response to bacteria present in more anaerobic conditions, and hypersensitivity of epithelial cells to pro-inflammatory stimuli at 2% oxygen, which may have implications for disease pathogenesis and/or therapy.

Surface modification of natural fibers using bacteria:depositing bacterial cellulose onto natural fibers to create hierarchical fiber reinforced nanocomposites

Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of natural fibers by utilizing bacteria (Acetobacter xylinum) to deposit nanosized bacterial cellulose around natural fibers, which enhances their adhesion to renewable polymers. This paper describes the process of modifying large quantities of natural fibers with bacterial cellulose through their use as substrates for bacteria during fermentation. The modified fibers were characterized by scanning electron microscopy, single fiber tensile tests, X-ray photoelectron spectroscopy, and inverse gas chromatography to determine their surface and mechanical properties. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate and poly(L-lactic acid) was quantified using the single fiber pullout test. © 2008 American Chemical Society.

Isolation and characterisation of bacteria associated with flying insects in hospitals, with particualr emphasis on Clostridum difficile

Clostridium difficile is a bacterial healthcare-associated infection, which houseflies Musca domestica may transfer due to their synanthropic nature. The aims of this thesis were to determine the ability of M. domestica to transfer C. difficile mechanically and to collect and identify flying insects in UK hospitals and classify any associated bacteria. M. domestica exposed to independent suspensions of vegetative cells and spores of C. difficile were able to mechanically transfer the bacteria on to agar for up to 4 hours following exposure. C. difficile could be recovered from fly excreta for 96hrs and was isolated from the M. domestica alimentary canal. Also confirmed was the carriage of C. difficile by M. domestica larvae, although it was not retained in the pupae or in the adults that subsequently developed. Flying insects were collected from ultra-violet light flytraps in hospitals. Flies (order Diptera) were the most commonly identified. Chironomidae were the most common flies, Calliphora vicina were the most common synanthropic fly and ‘drain flies’ were surprisingly numerous and represent an emerging problem in hospitals. External washings and macerates of flying insects were prepared and inoculated onto a variety of agars and following incubation bacterial colonies identified by biochemical tests. A variety of flying insects, including synanthropic flies (e.g. M. domestica and C. vicina) collected from UK hospitals harboured pathogenic bacteria of different species. Enterobacteriaceae were the group of bacteria most commonly isolated, followed by Bacillus spp, Staphylococci, Clostridia, Streptococci and Micrococcus spp. This study highlights the potential for M. domestica to contribute to environmental persistence and spread of C. difficile in hospitals. Also illustrated is the potential for flying insects to contribute to environmental persistence and spread of other pathogenic bacteria in hospitals and therefore the need to implement pest control as part of infection control strategies.