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Biomedical subjects

F Burke

Publications and source records attributed to F Burke.

At least 19 recordsLinked to original sources
PubMed2006

Attitudes of general dental practitioners in Europe to the microbial risk associated with dental unit water systems.

UNLABELLED: Dental Unit Water Systems (DUWS) are used in dental practices to provide water for cooling of dental equipment and irrigation of the oral cavity. However, they have been demonstrated to be contaminated with micro-organisms. There are currently no European Union (EU) Commission guidelines for the microbial quality of water discharged by DUWS. This study was part of an EU research programme to investigate the microbial contamination of DUWS in general dental practice (GDP) in the UK, Denmark, Germany, The Netherlands, Ireland, Greece and Spain. OBJECTIVE: To undertake a questionnaire survey on the type of DUWS in use and determine the attitude of GDPs to the risk of microbial infection from DUWS. MATERIALS AND METHODS: The questionnaire was written and translated into the language of each country before being posted to each participating dentist. Dentists were asked to complete the questionnaire survey and return it by post. RESULTS AND CONCLUSIONS: The major findings were that the majority of dentists did not clean, disinfect or determine the microbial load of their DUWS, and that dentists would welcome regular monitoring and advice on maintaining their DUWS; the introduction of guidelines; and recommendations on controlling the microbial load of DUWS.

Attitude of Health Personnel↗
PubMed2006

Comparison of the efficacies of disinfectants to control microbial contamination in dental unit water systems in general dental practices across the European Union.

Water delivered by dental unit water systems (DUWS) in general dental practices can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWS provide a reservoir for microorganisms and should be controlled. This study compared disinfection products for their ability to meet the American Dental Association's guideline of <200 CFU x ml(-1) for DUWS water. Alpron, BioBlue, Dentosept, Oxygenal, Sanosil, Sterilex Ultra, and Ster4Spray were tested in DUWS (n = 134) in Denmark, Germany, Greece, Ireland, The Netherlands, Spain, and the United Kingdom. Weekly water samples were tested for total viable counts (TVCs) on yeast extract agar, and, where possible, the effects of products on established biofilm (TVCs) were measured. A 4- to 5-week baseline measurement period was followed by 6 to 8 weeks of disinfection (intermittent or continuous product application). DUWS water TVCs before disinfection ranged from 0 to 5.41 log CFU x ml(-1). Disinfectants achieved reductions in the median water TVC ranging from 0.69 (Ster4Spray) to 3.11 (Dentosept) log CFU x ml(-1), although occasional high values (up to 4.88 log CFU x ml(-1)) occurred with all products. Before treatment, 64% of all baseline samples exceeded American Dental Association guidelines, compared to only 17% following commencement of treatment; where tested, biofilm TVCs were reduced to below detectable levels. The antimicrobial efficacies of products varied (e.g., 91% of water samples from DUWS treated with Dentosept or Oxygenal met American Dental Association guidelines, compared to 60% of those treated with Ster4Spray). Overall, the continuously applied products performed better than those applied intermittently. The most effective products were Dentosept and Oxygenal, although Dentosept gave the most consistent and sustained antimicrobial effect over time.

Biofilms↗
PubMed2004

Use of sensorineural tests in a large volume of medico-legal compensation claims for HAVS.

BACKGROUND: The Department of Trade and Industry set up a contract to examine miners and ex-miners claiming compensation for hand-arm vibration syndrome (HAVS). They had been exposed to hand-transmitted vibration. Over 100,000 have now been examined using sensorineural tests as part of that process. AIMS: The purpose of this paper was to examine the internal consistency of the vibrotactile threshold test (VTT) and the thermal aesthesiometry test (TA). METHODS: In 18 centres across the UK, nurses were trained to perform the measurement of VTT and TA in a controlled standardized manner. These tests were to aid the staging of the neurological component of the Stockholm Workshop Scales. The staging of this component was modified by dividing stage 2SN into 2SN (early) and 2SN (late). The test results and an automatic neurological staging were presented to the examining doctor following the clinical examination. The results of these sensorineural tests were held on a central database. The results and analysis of the first 57,000 tests are reported. RESULTS: The correlations within the VTT and TA scores were consistent with reliable measures. However, these correlations were not of such strength as to allow reliance on the results of a single test when making an assessment of the severity of neurological damage. CONCLUSIONS: Different end organs and nerve fibres should be tested when making an assessment of damage in the sensorineural component of HAVS. The correlations demonstrated for the VTT and TA suggest that they are of value in assessing these claimants and would be for other vibration exposed workers.

Arm↗
PubMed2004

Microbiological evaluation of dental unit water systems in general dental practice in Europe.

A range of opportunistic pathogens have been associated with dental unit water systems (DUWS), particularly in the biofilms that can line the tubing. This study therefore aimed to assess the microbiology of DUWS and biofilms in general dental practices across seven European countries, including the United Kingdom (UK), Ireland (IRL), Greece (GR), Spain (ES), Germany (D), Denmark (DK) and the Netherlands (NL). Water supplied by 51% of 237 dental unit water lines exceeded current American Dental Association recommendations of < or = 200 colony-forming units (CFU) ml(-1). Microbiological loading of the source waters was between 0 (Denmark, the Netherlands and Spain) and 4.67 (IRL) log CFU ml(-1); water line samples from the DUWS ranged from 1.52 (ES) to 2.79 (GR) log CFU ml(-1); and biofilm counts ranged from 1.49 (GR) to 3.22 (DK) log CFU.cm(-2). Opportunistic pathogens such as legionellae (DK and ES), including Legionella pneumophila SG1 (DK and GR), and Mycobacterium spp. (DK, NL, GR, D and ES) were recovered occasionally. Presumptive oral streptococci (ES and NL), oral anaerobes (GR), Candida spp. (UK, NL and ES) and blood (GR and IRL) were detected at relatively low frequencies, but their presence indicated a failure of the 3-in-1 antiretraction valve, leading to back siphonage of oral fluids into the water and biofilm phase. These findings confirm that a substantial proportion of DUWS have high levels of microbial contamination, irrespective of country, type of equipment and source water. The study emphasizes the need for effective mechanisms to reduce the microbial burden within DUWS, and highlights the risk of occupational exposure and cross-infection in general dental practice.

Bacteria↗
PubMed2003

Cold provocation testing and hand-arm vibration syndrome--an audit of the results of the Department of Trade and Industry scheme for the evaluation of miners.

BACKGROUND: Hand-arm vibration syndrome (HAVS) is a major industrial disease that causes considerable morbidity among workers exposed to vibration. Compensation is paid to those affected in civil claims against employers and (in the UK) in claims made under Social Security legislation rules for Prescribed Disease A11. Diagnostic tests have been proposed but most are not objective. The cold provocation test (CPT), which is objective, is often included in the evaluation of HAVS. METHODS: A continuous audit was made of the findings recorded at the 18 HAVS test centres in the UK established to evaluate miners. The audit, and its outcome, were monitored by the Medical Reference Panel who advise the Department of Trade and Industry. This audit report constitutes the second analysis of the findings relating to the CPT. RESULTS: The CPT, with measurement of digital rewarming times, is of no value in assessing vibration-induced damage to the hands. CONCLUSION: In its present format, the CPT should not be used for evaluating the vascular component of HAVS.

Adult↗
PubMed2001

Sonographic examination of lateral epicondylitis.

OBJECTIVE: The purpose of this study was to describe the sonographic appearance of the common extensor origin in cadavers and asymptomatic volunteers, and to relate this appearance to the findings in patients with lateral epicondylitis. SUBJECTS AND METHODS: Seventy-two elbows in 71 patients with lateral epicondylitis were examined on sonography. Most of the patients (60/71) gave a history of repetitive microtrauma. The injuries were evaluated with respect to location and severity. Focal areas of degeneration, discrete cleavage tears, and involvement of the lateral collateral ligament were identified. Calcification and bony changes were noted. The appearance of the normal common extensor tendon was described, and cadaveric specimens were dissected. Twenty-one patients subsequently underwent surgery. RESULTS: The normal common extensor origin is composed of longitudinal fibrils bound closely with the extensor carpi radialis brevis constituting most of the deep fibers, with the extensor digitorum making up the superficial part. The lateral collateral ligament can be identified as a discrete and separate band. The most common appearance of lateral epicondylitis is a focal hypoechoic area in the deep part of the tendon (46/72). These focal areas were identified at surgery and corresponded histologically to collagen degeneration with fibroblastic proliferation. Often discrete cleavage planes traversing the tendon were manifest as partial (18/72) and complete (2/72) tears. The lateral collateral ligament was involved in eight of 72 elbows. CONCLUSION: Sonography of the common extensor origin can be used to confirm lateral epicondylitis in patients with lateral elbow pain and provide information about the severity of the disease.

Adult↗
PubMed2001

Surface hardness of light-activated resin composites cured by two different visible-light sources: an in vitro study.

OBJECTIVE: Microhardness values of upper and lower surfaces of disk specimens of 3 commercially available resin composites were compared and cured using both the traditional halogen source and a plasma arc lamp. METHOD AND MATERIALS: Twenty samples of each of the resin composites were cured in nylon washers. Ten samples of each composite were cured using the appropriate halogen lamp protocol, and 10 samples of each were cured using the plasma lamp protocol. Surface microhardness measurements were carried out using a calibrated Vickers indenter on both top and bottom surfaces after 7 days of storage in air at 20 degrees C. Statistical analysis of the data was carried out using a commercial statistical package. The data for top and bottom surfaces were analyzed separately using a repeated measures analysis of variance (ANOVA). RESULTS: Lamp, composite, and the interaction between lamp and composite were significant in determining the results for both top and bottom surfaces of the disk-shaped specimens. The plasma lamp yielded lower hardness values for all surfaces compared with the halogen source, but the size of the difference depended on the composite. CONCLUSION: Caution must be exercised in the plasma irradiation of resin composites as a curing method due to the possibility of reduced surface microhardness values that may reflect a reduced percent conversion of monomer to polymer.

Analysis of Variance↗
PubMed1999

Mice deficient in tumor necrosis factor-alpha are resistant to skin carcinogenesis.

Given the associations between chronic inflammation and epithelial cancer, we studied susceptibility to skin carcinogenesis in mice deficient for the pro-inflammatory cytokine TNF-alpha (refs. 5,6). TNF-alpha(-/-) mice were resistant to development of benign and malignant skin tumors, whether induced by initiation with DMBA and promotion with TPA or by repeated dosing with DMBA. TNF-alpha(-/-) mice developed 5-10% the number of tumors developed by wild-type mice during initiation/promotion and 25% of those in wild-type mice after repeated carcinogen treatment. TNF-alpha could influence tumor and stromal cells during tumor development. The early stages of TPA promotion are characterized by keratinocyte hyperproliferation and inflammation. These were diminished in TNF-alpha(-/-) mice. TNF-alpha was extensively induced in the epidermis, but not the dermis, in TPA-treated wild-type skin, indicating that dermal inflammation is controlled by keratinocyte TNF-alpha production. Deletion of a TNF-alpha inducible chemokine also conferred some resistance to skin tumor development. TNF-alpha has little influence on later stages of carcinogenesis, as tumors in wild-type and TNF-alpha(-/-) mice had similar rates of malignant progression. These data provide evidence that a pro-inflammatory cytokine is required for de novo carcinogenesis and that TNF-alpha is important to the early stages of tumor promotion. Strategies that neutralize TNF-alpha production may be useful in cancer treatment and prevention.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1999

Cytotoxic response of ovarian cancer cell lines to IFN-gamma is associated with sustained induction of IRF-1 and p21 mRNA.

Interferon-gamma (IFN-gamma) has some anti-tumour activity in human ovarian cancer. This cytokine inhibited proliferation in three of four ovarian cancer cell lines in vitro. We then compared the action of IFN-gamma in two cell lines, one sensitive and one resistant to its growth inhibitory effects. IFN-gamma signalling appeared normal in both cell lines, with stat1 DNA binding activity detectable at 30 min. Continuous exposure to IFN-gamma for 2-3 days was necessary for an irreversible effect on cell growth and apoptosis in cells sensitive to growth inhibition. During this time there was an increase in mRNA for the CKI p21, but no alterations in mRNA levels for other members of the CKI family. Maintenance of p21 mRNA required continuous mRNA synthesis. mRNA for the transcription factor IRF-1 was also induced in growth inhibited cells with similar kinetics to those observed for p21. Maximal induction of both p21 and IRF-1 mRNA was observed after 2-3 days IFN-gamma exposure as the cells became committed to cell death. There was also a rapid increase in p21 and IRF-1 mRNA in cells resistant to the growth inhibitory effects of IFN-gamma, but this increase was not maintained. Thus, continuous interaction with the IFN-gamma receptor, together with a sustained induction of p21 and IRF-1, is associated with growth inhibitory and apoptotic effects of IFN-gamma in ovarian cancer cells.

Adenocarcinoma↗
PubMed1999

Cytokines (IFNs, TNF-alpha, IL-2 and IL-12) and animal models of cancer.

Cytokines are a complex family of mediators that influence many aspects of tumour cell biology. Whether they are used as a therapy or produced locally during the process of tumorigenesis, they are able to act on tumour cells, on the tumour stroma and on the host itself. Animal models have played key roles in optimizing doses and schedules, and have been useful in determining net effects in the tissue microenvironment. Whilst early studies used xenogeneic and syngeneic systems, more recently gene and protein delivery systems have been used to introduce ectopically expressed high and continuous levels of cytokines. This review will discuss the application of some animal model systems that have been investigated to further understand the role cytokines play in cancer, and will concentrate on those cytokines for which there are the most experimental animal model data.

Animals↗
PubMed1998

Hypoxia down-regulates MCP-1 expression: implications for macrophage distribution in tumors.

Monocyte chemoattractant protein 1 (MCP-1) is likely to contribute to the macrophage infiltrate in human ovarian carcinomas. Although MCP-1 is predominantly expressed by the tumor parenchyma, macrophages accumulate at highest density in necrotic regions, which are associated with low oxygen tensions. Tumor necrosis factor alpha (TNF-alpha) can stimulate MCP-1 production and is also present within ovarian carcinomas. We have investigated the effect of hypoxia both on MCP-1 expression in ovarian cancer cell lines and monocyte migration. Hypoxia down-regulated TNF-alpha-induced MCP-1 mRNA and protein production by ovarian cancer cells. The effect was mimicked by cobalt chloride and desferrioxamine, consistent with a specific oxygen-sensing mechanism. Unlike antioxidants, hypoxia did not inhibit nuclear factor KB mobilization. Monocyte migration in response to MCP-1 was also diminished under hypoxic conditions. Down-regulation of MCP-1 expression and the inhibition of monocyte migration are independent effects of hypoxia that may contribute to the distribution of macrophages within ovarian tumors.

Antigens, CD↗
PubMed1997

Interferon gamma induces cell cycle arrest and apoptosis in a model of ovarian cancer: enhancement of effect by batimastat.

Locoregional human IFN-gamma may have activity against refractory ovarian cancer. We investigated this further in an ovarian cancer xenograft model. Administered at clinically relevant doses, intraperitoneal IFN-gamma prolonged the survival of mice bearing multiple established peritoneal tumours, with optimal treatment giving a 3-6-fold increase in median survival time. Daily dosing, which was superior to intermittent treatment, decreased DNA synthesis and induced apoptosis in tumour cells with maximal effects after 7-21 days treatment. This was preceded by an increase in p53 protein at 48 h. The effect of IFN-gamma was not enhanced by sequential treatment with carboplatin. However, the matrix metalloprotease inhibitor, batimastat, further increased mouse survival when given after IFN-gamma. Thus IFN-gamma is cytotoxic to ovarian epithelial cells in vivo and intensive locoregional dosing over short periods is effective. Sequential administration of novel agents that perturb the host/tumour relationship may be of benefit.

Animals↗
PubMed1996

A cytokine profile of normal and malignant ovary.

We defined a cytokine mRNA profile of 12 ovarian cancer biopsies, 10 normal/benign biopsies, six ovarian cancer cell lines and three ovarian cancer xenografts, using RT-PCR. The profile, based on screening for 25 cytokines and 12 receptor mRNAs, was rich in growth factors, pro-inflammatory cytokines and chemokines, but weak in lymphocyte-associated cytokines. The pattern was unique to ovarian tissue, but similar in normal, benign and malignant biopsies, with > 80% samples expressing 16 cytokines in common. Fourteen of these were also expressed by > 65% cell lines, but fewer were detected in xenografts. Potential autocrine loops existed for IL-1, IGF-1, M-CSF, GM-CSF and TNF-alpha. IL-4 and IFN-gamma receptors were expressed in absence of ligand. Chemokines RANTES, MIP-1 alpha and MIP-1 beta were expressed in biopsies, but were rarely detected in cell lines and absent from xenografts. IGF-1 and its receptor was expressed in every sample, as was IFN-gamma receptor. Another 10 cytokine mRNAs and six receptors were expressed in > 80% samples. These may contribute to key survival/growth loops. Similarities between normal and malignant biopsies suggest that analogous processes of remodelling and repair occur. RT-PCR proved a rapid, reproducible screen, but further assays are required to detect quantitative differences between normal and malignant tissues and tumour models.

Animals↗
PubMed1996

Cytokines in animal models of cancer.

Cytokines are a complex family of mediators that play a wide role in development, immunity, inflammation and tissue repair. Their use in therapy is still in its infancy and animal models have a key role to play in optimizing doses and schedules. Whilst xenogeneic and syngeneic transplantable systems have traditionally been used to look at the effects of cytokines in tumour models, oncogene transgenic mice prone to develop cancer, may now have a role to play. Moreover, gene therapy has allowed the investigation of ectopically expressed high and continuous levels of cytokines. We will attempt to review the literature on the effect of cytokines and their combinations in these models of cancer.

Animals↗