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Biomedical subjects

R Davies

Publications and source records attributed to R Davies.

At least 19 recordsLinked to original sources
PubMed2006

Lung volume reduction surgery for diffuse emphysema.

BACKGROUND: Lung volume reduction surgery (LVRS) has been re-introduced for treating patients with severe diffuse emphysema. It is a procedure that aims to improve long-term daily functioning, although it is costly and may also be associated with a high risk of mortality. OBJECTIVES: To assemble evidence from randomised controlled trials for the effectiveness of LVRS, and identify optimal surgical techniques. SEARCH STRATEGY: Randomised controlled trials were identified using the Cochrane Airways Group Chronic Obstructive Pulmonary Disease (COPD) register. Searches are current to September 2005. SELECTION CRITERIA: Randomised controlled trials that studied the safety and efficacy of LVRS in patients with diffuse emphysema were included. Studies were excluded if they investigated giant or bullous emphysema. DATA COLLECTION AND ANALYSIS: Two independent review authors assessed trials for inclusion and extracted data. Where possible, data from more than one study were combined using RevMan 4.2 software. MAIN RESULTS: Eight studies (1663 participants) met the entry criteria of the review. One study accounted for 73% of the participants recruited. Study quality was high, although blinding in studies was not possible. Ninety day mortality was significantly greater in all those who underwent LVRS (odds ratio 6.57 (95% CI 3.34 to 12.95), four studies, N = 1415). A subgroup analysis by risk status suggested that there was a subgroup of participants who were consistently at a significant risk of death, although this was only measured in one large study. The ninety day mortality data indicated that death was more likely with LVRS irrespective of risk status identified in one large study. Improvements in lung function, quality of life and exercise capacity were more likely with LVRS than with usual follow-up. AUTHORS' CONCLUSIONS: The evidence summarised in this review is drawn from one large study, and several smaller trials. The findings from the large study indicated that in patients who survive up to three months post-surgery, there were significantly better health status and lung function outcomes in favour of surgery compared with usual medical care. Patients identified post hoc as being of high risk of death from surgery were those with particularly impaired lung function and poor diffusing capacity and/or homogenous emphysema. Further research should address the effect of this intervention on exacerbations and rate of decline in lung function and health status.

Emphysema↗
PubMed2006

A comparison of the use of Trachlight and Eschmann multiple-use introducer in simulated difficult intubation.

BACKGROUND AND OBJECTIVE: The Eschmann multiple-use introducer is widely used in the management of difficult intubations. Transillumination of the neck is less commonly used. We conducted a randomized crossover study comparing the Trachlight lightwand and Eschmann multiple-use introducer in simulated difficult intubation. METHODS: Sixty-four healthy patients were studied using a standard anaesthetic and full muscle relaxation assessed by train of four. A Macintosh laryngoscope was then inserted and then lowered to simulate a Grade 3 view. Tracheal placement was attempted with both Trachlight lightwand and Eschmann multiple-use introducer in a randomized order. Anaesthetists placing the devices had extensive experience with the Eschmann multiple-use introducer, but only 15 previous uses of the Trachlight. Success rates and time for tracheal placement were recorded. RESULTS: The Eschmann multiple-use introducer and Trachlight were successfully placed in 96.8% and 93.7%, respectively (n.s.). Mean (SD) time to intubation for Eschmann multiple-use introducer and Trachlight were 15(6) and *21(13), respectively (*P < 0.001). CONCLUSION: The Trachlight is a potentially useful alternative to the Eschmann multiple-use introducer in difficult intubation.

Female↗
PubMed2006

The rapid formation of a large rotating disk galaxy three billion years after the Big Bang.

Observations and theoretical simulations have established a framework for galaxy formation and evolution in the young Universe. Galaxies formed as baryonic gas cooled at the centres of collapsing dark-matter haloes; mergers of haloes and galaxies then led to the hierarchical build-up of galaxy mass. It remains unclear, however, over what timescales galaxies were assembled and when and how bulges and disks--the primary components of present-day galaxies--were formed. It is also puzzling that the most massive galaxies were more abundant and were forming stars more rapidly at early epochs than expected from models. Here we report high-angular-resolution observations of a representative luminous star-forming galaxy when the Universe was only 20% of its current age. A large and massive rotating protodisk is channelling gas towards a growing central stellar bulge hosting an accreting massive black hole. The high surface densities of gas, the high rate of star formation and the moderately young stellar ages suggest rapid assembly, fragmentation and conversion to stars of an initially very gas-rich protodisk, with no obvious evidence for a major merger.

Journal Article↗
PubMed2006

A review of health care models for coronary heart disease interventions.

This article reviews models for the treatment of coronary heart disease (CHD). Whereas most of the models described were developed to assess the cost effectiveness of different treatment strategies, other models have also been used to extrapolate clinical trials, for capacity and resource planning, or to predict the future population with heart disease. In this paper we investigate the use of modelling techniques in relation to different types of health intervention, and we discuss the assumptions and limitations of these approaches. Many of the models reviewed in this paper use decision tree models for acute or short term interventions, and Markov or state transition models for chronic or long term interventions. Discrete event simulation has, however, been used for more complex whole system models, and for modelling resource-constrained interventions and operational planning. Nearly all of the studies in our review used cohort-based models rather than population based models, and therefore few models could estimate the likely total costs and benefits for a population group. Most studies used de novo purpose built models consisting of only a small number of health states. Models of the whole disease system were less common. The model descriptions were often incomplete. We recommend that the reporting of model structure, assumptions and input parameters is more explicit, to reduce the risk of biased reporting and ensure greater confidence in the model results.

Coronary Disease↗
PubMed2006

Semiquantitative assessment of the distribution of Salmonella in the environment of caged layer flocks.

AIMS: To evaluate a semiquantitative technique for the enumeration of Salmonella in the environment of layer flocks and to compare findings with those of a standard qualitative technique. METHODS AND RESULTS: Samples were taken from faeces, floor dust, dust on cages, feeders and egg belts. After mixing with buffered peptone water, serial dilutions were prepared and culture was performed using pre-enrichment, then plating on semisolid selective and solid isolation media. Comparison with a qualitative pre-enrichment technique indicated a similar sensitivity for both methods despite smaller sample sizes. The numbers of Salmonella detected for a site or sample type did not correlate closely with the prevalence of positive samples. CONCLUSIONS: The sensitive detection and quantification of Salmonella in the flock environment is practicable with the technique described. Quantitative data in many cases do not correlate with qualitative findings. SIGNIFICANCE AND IMPACT OF THE STUDY: The significance of certain environmental factors and interventions in the maintenance and dissemination of Salmonella in poultry houses may be over- or under-represented by prevalence data alone. The technique described allows the issue of poultry house contamination to be examined from a new perspective.

Animal Husbandry↗
PubMed2006

Using simulation to estimate the cost effectiveness of improving ambulance and thrombolysis response times after myocardial infarction.

OBJECTIVES: To quantify the health gains and costs associated with improving ambulance and thrombolysis response times for acute myocardial infarction. DESIGN: A computer simulation model. PATIENTS/SETTINGS: Patients experiencing acute myocardial infarction in England. INTERVENTIONS: Improving the ambulance response time to 75% of calls reached within 8 minutes and the hospital arrival to thrombolysis time interval (door-to-needle time) to 75% receiving it within 30 minutes and 20 minutes, compared to best estimates of response times in the mid-1990s. MAIN OUTCOME MEASURES: Deaths prevented, life years saved, and discounted cost per life year saved. RESULTS: Improving the ambulance response to 75% of calls within 8 minutes resulted in an estimate of 5 deaths prevented or 57 life years saved per million population per year, with a discounted incremental cost per life year saved of 8540 pounds sterling over 20 years. The corresponding benefit of improving the door-to-needle time to 75% of myocardial infarction patients within 30 minutes was an estimated 2 deaths prevented and 15 life years saved per million population per year, with a discounted incremental cost per life year saved of between 10,150 pounds sterling to 54,230 pounds sterling over 20 years. Little further gain was associated with reaching the 20 minute target. Combining ambulance and thrombolysis targets resulted in 70 life years saved per million population per year. CONCLUSIONS: Improving ambulance response times appears to be cost effective. Reducing door-to-needle time will have a smaller effect at an uncertain cost. Further benefits may be gained from reducing the time from onset of symptoms to starting thrombolysis.

Aged↗
PubMed2006

Is secondary radiological follow-up of infants with a family history of developmental dysplasia of the hip necessary?

The practice of regular radiological follow-up of infants with a positive family history of developmental dysplasia of the hip is based on the widespread belief that primary acetabular dysplasia is a genetic disorder which can occur in the absence of frank subluxation or dislocation. We reviewed all infants who were involved in our screening programme for developmental dysplasia of the hip, between November 2002 and January 2004, and who had a normal clinical and ultrasound examination of the hip at six to eight weeks of age, but who, because of a family history of developmental dysplasia of the hip, had undergone further radiography after an interval of 6 to 12 months. The radiographs of 89 infants were analysed for signs of late dysplasia of the hip and assessed independently by three observers to allow for variability of measurement. There were 11 infants (11%) lost to follow-up. All the patients had normal radiographs at the final follow-up and none required any intervention. We therefore question the need for routine radiological follow-up of infants with a positive family history of developmental dysplasia of the hip, but who are normal on clinical examination and assessment by ultrasound screening when six to eight weeks old.

Acetabulum↗
PubMed2006

Presence of Salmonella in the red meat abattoir lairage after routine cleansing and disinfection and on carcasses.

Foodborne pathogens, such as Salmonella, may remain in abattoir lairages after cleansing and pose a risk of transfer and contamination from one processing day to the next. These organisms may be transferred to the outer surface of animals held in lairage facilities, and the skin or hide may be a significant source of microbial contamination on the red meat carcasses subsequently produced. Sponge samples were taken from various sites in the lairage (n = 556), and single-pass sponge samples were taken from one side of red meat carcasses (n = 1,050) at five commercial abattoirs in Southwest England and tested for the presence of Salmonella. Of these, 6.5% of lairage samples were positive, containing estimated numbers of up to 10(4) Salmonella organisms per sampled area (50 by 50 cm). Salmonella was found on 9.6% of 240 lamb carcasses, 12.7% of 330 beef carcasses, 31% of 70 pig carcasses, 20% of 80 calf carcasses younger than 14 days of age, and none of 330 cull cow and bull carcasses. Subtyping divided the 137 isolates into seven serogroups and three pulsed-field gel electrophoresis clusters, and sensitivity testing against a bank of 16 antimicrobials indicated that 47 isolates had resistance to one or more antimicrobial agents. These results indicate that Salmonella contamination can persist in the lairage environment from one processing day to the next and that Salmonella is present on red meat carcasses, although the implications of residual lairage contamination on carcass meat microbiology are not clear from this study. Abattoir owners should take steps to reduce the level of contamination in their premises to prevent contamination from being carried over from one processing day to the next.

Abattoirs↗
PubMed2005

The genome of the social amoeba Dictyostelium discoideum.

The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.

ATP-Binding Cassette Transporters↗
PubMed2005

The distribution of Tannerella forsythia in an adolescent and adult population.

BACKGROUND: The fact that Tannerella forsythia, an important periopathogen, is difficult to cultivate from mixed infections has impeded precise estimates of its distribution within a given population. In order to discern T. forsythia alone from the mixed infection of plaque, the use of sensitive 16S ribosomal RNA based polymerase chain reaction (PCR) detection is necessary. OBJECTIVES: The aim of the present study was to determine the distribution of T. forsythia in an adult and in an adolescent population. MATERIAL AND METHODS: Subgingival plaque samples were obtained from 498 Australian adults and from 228 adolescent subjects from Manchester, UK. Tannerella forsythia was detected using PCR and confirmed by restriction analysis. Semi-quantitation of the organisms was carried out using two specific primers of differing sensitivities. RESULTS: In the adolescent population, 25% were found to carry T. forsythia, albeit in relatively low numbers. In the adult population, a total of 37.8% and 11% were found to carry the organism with primer 2 and primer 1, respectively, suggesting that around 27% had between 10(3) and 10(7) organisms. Although there was an apparent increased proportion of T. forsythia positive subjects in those aged > or = 50 years, this was not statistical significant. However, T. forsythia positive male smokers showed increased disease severity compared with T. forsythia negative subjects. CONCLUSION: This study has shown that at least 25% of the adolescent population carry low numbers of T. forsythia, whereas at least 37% of adults carry the organism, with some 11% having relatively high numbers. The relationship between T. forsythia and disease progression in these populations, however, remains to be determined.

Adolescent↗
PubMed2005

Factors associated with infection by Pseudomonas aeruginosa in adult cystic fibrosis.

Cross-infection with Pseudomonas aeruginosa is an emerging issue in the care of patients with cystic fibrosis (CF). This study sought to determine the extent of, and patient factors associated with, cross-infection in a tertiary referral adult CF centre. P. aeruginosa isolates were genotyped into two groups between November 2001 and February 2003, using pulsed-field gel electrophoresis after DNA digestion by the SpeI endonuclease, and identified as clustered if there was >80% homology in the macrorestriction profiles. Patient factors and measures of disease severity were identified a priori. In total, 157 out of 227 patients had a P. aeruginosa isolate genotyped. Of these, 94 patients (60%) were infected with clustered genotypes and 47 (30%) were infected with the newly described "Midlands 1" (Md1) genotype. A further 18 patients were infected with the previously identified "Liverpool" genotype and two with the "Manchester" genotype. Logistic regression analysis revealed that the predominant predictor of infection with Md1 was age at the time of referral to the centre, suggesting that infection may have occurred prior to referral in some patients. Md1 demonstrated a relatively benign anti-biogram and did not appear to be associated with more severe disease. In conclusion, the present study provides further evidence of the emerging importance of Pseudomonas aeruginosa cross-infection in cystic fibrosis.

Adult↗
PubMed2005

The care of pin sites with external fixation.

Two protocols for the operative technique and care of the pin-site with external fixation were compared prospectively. There was a total of 120 patients with 46 in group A and 74 in group B. Infection was defined as an episode of pain or inflammation at a pin site, accompanied by a discharge which was either positive on bacterial culture or responded to a course of antibiotics. Patients in group B had a lower proportion of infected pin sites (p = 0.003) and the time to the first episode of infection was longer (p < 0.001). The risk of pin-site infection is lower if attention is paid to avoiding thermal injury and local formation of haematoma during surgery and if after-care includes the use of an alcoholic antiseptic and occlusive pressure dressings.

Bone Nails↗
PubMed2004

The associations of anxiety, depression and personal illness representations with glycaemic control and health-related quality of life in patients with type 2 diabetes mellitus.

OBJECTIVE: This study examined the interrelationships of anxiety, depression and personal illness representations with glycaemic control and health-related quality of life in adults with Type 2 diabetes. METHODS: One hundred eighty-four consecutive patients with Type 2 diabetes mellitus completed the Illness Perception Questionnaire (IPQ), the Well-Being Scale (WBQ) and the Short Form 36 Health Survey Questionnaire (SF-36). Demographic characteristics, details of diabetes status (duration of diabetes, treatments and complications) and glycosylated haemoglobin (HbA1c) were recorded. RESULTS: Depression was correlated with greater perceived symptom load (r = .48, P < .01), worse anticipated consequences (r = -.41, P < .01) and perceived lack of control of diabetes (r = .28, P < .01). After controlling for demographic and illness characteristics, personal illness representations relating to symptom load and anticipated consequences were independently associated with the SF-36 physical functioning score, contributing an additional 15% to the variance. WBQ depression and anxiety scores, along with IPQ control and consequences, were independently associated with SF-36 mental function score, contributing a further 51% to the variance after controlling for demographic and illness details. Neither IPQ nor WBQ scales were associated with HbA1c after controlling for demographic and medical illness details. CONCLUSION: Anxiety, depression and negative beliefs about illness influence physical and mental functioning, but not metabolic control in patients with diabetes.

Aged↗
PubMed2004

Persistent colonization with Tannerella forsythensis and loss of attachment in adolescents.

Colonization with Tannerella forsythensis may characterize the conversion of periodontally healthy sites into diseased sites. This three-year study describes the prevalence of T. forsythensis and its relationship to clinical loss of attachment (LOA) in a group of adolescents considered at risk of developing early chronic periodontitis. Adolescents with (LOA+) and without (LOA-) loss of attachment were examined at baseline and 1.5 and 3 yrs subsequently. On each occasion, attachment loss was measured on selected teeth, and the presence of T. forsythensis in their subgingival plaque samples was determined by PCR. T. forsythensis prevalence in LOA+ subjects at baseline (64%) increased to 82% and 86% on subsequent examinations. In contrast, prevalence of T. forsythensis in LOA- subjects was always significantly lower (25%, 36%, and 32%, respectively). The odds of loss of attachment were 8.16 times greater in subjects infected with T. forsythensis at each examination. These results suggest that T. forsythensis is strongly associated with loss of attachment in this adolescent population.

Adolescent↗
PubMed2003

Effects of vaccination and other preventive methods for Salmonella enteritidis on commercial laying chicken farms.

The effect of introducing vaccinated commercial laying chickens on to farms, which previously had laying flocks that were infected with Salmonella Enteritidis, was investigated by sampling faeces and environmental samples, and in some cases spent hens. In 15 of 17 free-range flocks vaccination eliminated any evidence of infection. In 11 barn egg production flocks, vaccination produced similar results in four flocks on one farm but infection persisted in seven flocks on other farms. Vaccination of two consecutive cage layer flocks led to a gradual disappearance of the infection, but in 18 other flocks there was evidence of infection after vaccination. In one continuously occupied cage layer house, treatment by competitive exclusion was followed by a gradual disappearance of S Enteritidis in faeces and a substantial reduction in its levels in the environment. On four barn egg production sites disinfection with a formaldehyde, glutaraldehyde and quaternary ammonium compound disinfectant eliminated Salmonella species even though birds housed subsequently were not vaccinated. In three flocks that had been vaccinated for four years, S Enteritidis was still present. In most cases the poor performance of the vaccine was associated with severe rodent control problems and a poor standard of cleaning and disinfection.

Animals↗