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John Davison

Publications and source records attributed to John Davison.

11 recordsLinked to original sources
PubMed2006

Clinical and radiological outcome following total hip arthroplasty with an uncemented trabecular metal monoblock acetabular cup.

Uncemented acetabular components are associated with a significant incidence of polyethylene wear and secondary osteolysis. The new tantalum/polyethylene composite (Hedrocel) acetabular component is designed to reduce the polyethylene wear and to increase the longevity of the acetabular cups. We report our short- term clinical outcome and patient satisfaction following use of an uncemented tantalum acetabular component in a single centre. During 1999 to 2002, 113 uncemented tantalum acetabular cups were implanted in 105 patients in our institution. The average age at operation was 56.8 years. All patients were assessed pre- and post-operatively with the Oxford 12 item hip questionnaire and standard radiographs of the pelvis. At a mean follow-up of 32 months (range: 18 to 48), 112 Hedrocel cups were assessed in 104 patients. Subjective patient's satisfaction was also assessed. At the time of evaluation, one patient had died due to an unrelated cause. Eight patients had bilateral acetabular cups implanted. The mean Oxford hip score improved from 45 preoperatively to 14 post-operatively. Subjectively 99% were very satisfied or satisfied. Only one patient expressed dissatisfaction about the outcome of this surgery. Radiologically, there were no signs of cup loosening or wear. This study shows that at short-term the new uncemented tantalum/polyethylene composite (Hedrocel) acetabular component can yield a satisfactory clinical and radiological outcome and has a high patient satisfaction. Although the short-term result from our centre is very encouraging, similar results from other centres and longer follow-up are required.

Adult↗
PubMed2005

Risk mitigation of genetically modified bacteria and plants designed for bioremediation.

While the possible advantages of bioremediation and phytoremediation, by both recombinant microbes and plants, have been extensively reviewed, the biosafety concerns have been less extensively treated. This article reviews the possible risks associated with the use of recombinant bacteria and plants for bioremediation, with particular emphasis on ways in which molecular genetics could contribute to risk mitigation. For example, genetic techniques exist that permit the site-specific excision of unnecessary DNA, so that only the transgenes of interest remain. Other mechanisms exist whereby the recombinant plants or bacteria contain conditional suicide genes that may be activated under certain conditions. These methods act to prevent the spread and survival of the transgenic bacteria or plants in the environment, and to prevent horizontal gene flow to wild or cultivated relatives. Ways in which these genetic technologies may be applied to risk mitigation in bioremediation and phytoremediation are discussed.

Animals↗
PubMed2005

24-hour ambulatory electrocardiographic monitoring is unhelpful in the investigation of older persons with recurrent falls.

BACKGROUND: Although frequently used in the assessment of patients with falls, it is unclear whether 24-hour ambulatory electrocardiography contributes to their assessment in older persons. OBJECTIVE: To identify electrocardiographic abnormalities in patients with recurrent falls and case controls, and determine whether 24-hour ambulatory electrocardiography identifies causal arrhythmias for falls. DESIGN: Prospective case-control study. METHODS: 24-hour ambulatory electrocardiography recordings were compared for the type and prevalence of arrhythmias and symptom correlation in consecutive older subjects with recurrent falls attending the accident and emergency department and in case controls (no previous falls or syncope). ECG abnormalities were categorised as major (ventricular arrhythmia, pauses, <30 b.p.m., Mobitz II, complete heart block) and minor (multiple ectopics, paroxysmal atrial arrhythmia and other bradyarrhythmias). RESULTS: 128 fallers (76 +/-6 years) and 100 case controls (75 +/-5 years) were recruited. Co-medication and co-morbidity were similar in both groups. 49% (63) of recordings in fallers and 41% (41) of recordings in controls were abnormal. There was no difference between groups in the prevalence of major or minor abnormalities or of symptoms during recording (breathlessness, fatigue, chest pain and dizziness). Palpitations occurred in 10% of fallers and 13% of controls. One patient fell during monitoring with no associated rhythm abnormality. CONCLUSION: Multiple abnormalities are present on 24-hour ambulatory electrocardiography in older people whether or not they have experienced falls. 24-hour electrocardiography does not discriminate between fallers and non-fallers and is not helpful in the investigation of recurrent falls.

Accidental Falls↗
PubMed2005

Patients with recurrent falls attending Accident & Emergency benefit from multifactorial intervention--a randomised controlled trial.

OBJECTIVES: To determine the effectiveness of multifactorial intervention to prevent falls in cognitively intact older persons with recurrent falls. DESIGN: Randomised controlled trial of multifactorial (medical, physiotherapy and occupational therapy) post-fall assessment and intervention compared with conventional care. SETTING: Accident & Emergency departments in a university teaching hospital and associated district general hospital. SUBJECTS: 313 cognitively intact men and women aged over 65 years presenting to Accident & Emergency with a fall or fall-related injury and at least one additional fall in the preceding year; 159 randomised to assessment and intervention and 154 to conventional care. OUTCOME MEASURES: primary outcome was the number of falls and fallers in 1 year after recruitment. Secondary outcomes included injury rates, fall-related hospital admissions, mortality and fear of falling. RESULTS: There were 36% fewer falls in the intervention group (relative risk 0.64, 95% confidence interval 0.46-0.90). The proportion of subjects continuing to fall (65% (94/144) compared with 68% (102/149) relative risk 0.95, 95% confidence interval 0.81-1.12), and the number of fall-related attendances and hospital admissions was not different between groups. Duration of hospital admission was reduced (mean difference admission duration 3.6 days, 95% confidence interval 0.1-7.6) and falls efficacy was better in the intervention group (mean difference in Activities Specific Balance Confidence Score of 7.5, 95% confidence interval 0.72-14.2). CONCLUSION: Multifactorial intervention is effective at reducing the fall burden in cognitively intact older persons with recurrent falls attending Accident & Emergency, but does not reduce the proportion of subjects still falling.

Accidental Falls↗
PubMed2005

Allvar gullstrand.

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History, 19th Century↗
PubMed2005

Walter Rudolf Hess.

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History, 19th Century↗
PubMed2005

Renal hemodynamic effects of relaxin in humans.

Rat studies have convincingly demonstrated the essential role of the ovarian hormone relaxin in mediating gestational renal hemodynamic and osmoregulatory changes in that species. We describe a model in nonpregnant volunteers using exogenous hCG to stimulate the production and release of ovarian relaxin in order to assess renal hemodynamic responses. Women (n = 10) were serially studied +/- hCG stimulation during menstrual cycles with measurement of inulin, PAH, and neutral dextran clearances (to determine glomerular filtration rate [GFR], renal plasma flow [RPF], and glomerular porosity, respectively). Controls were women without ovarian function (n = 6) and men (n = 10). GFR and RPF were increased in the luteal phase compared to the follicular phase (15.3% increase in GFR, P < 0.005; 17.8% increase in RPF, P < 0.05). In controls, GFR and RPF were not significantly different between study occasions. Although exogenous hCG did not stimulate relaxin secretion in women without ovarian function or in men, it did so in normal women, but not into the pregnancy range. In no group were renal hemodynamics augmented by administered hCG. In naturally occurring cycles, increased serum relaxin is associated with augmented renal hemodynamics. As luteal stimulation with hCG failed to yield pregnancy relaxin levels, the use of exogenous relaxin for human administration is needed to further elucidate the renal vasodilatory properties of relaxin.

Adolescent↗
PubMed2003

Large-scale essential gene identification in Candida albicans and applications to antifungal drug discovery.

Candida albicans is the primary fungal pathogen of humans. Despite the need for novel drugs to combat fungal infections [Sobel, J.D. (2000) Clin Infectious Dis 30: 652], antifungal drug discovery is currently limited by both the availability of suitable drug targets and assays to screen corresponding targets. A functional genomics approach based on the diploid C. albicans genome sequence, termed GRACETM (gene replacement and conditional expression), was used to assess gene essentiality through a combination of gene replacement and conditional gene expression. In a systematic application of this approach, we identify 567 essential genes in C. albicans. Interestingly, evaluating the conditional phenotype of all identifiable C. albicans homologues of the Saccharomyces cerevisiae essential gene set [Giaever, G., Chu, A.M., Ni, L., Connelly, C., Riles, L., Veronneau, S., et al. (2002) Nature 418: 387-391] by GRACE revealed only 61% to be essential in C. albicans, emphasizing the importance of performing such studies directly within the pathogen. Construction of this conditional mutant strain collection facilitates large-scale examination of terminal phenotypes of essential genes. This information enables preferred drug targets to be selected from the C. albicans essential gene set by phenotypic information derived both in vitro, such as cidal versus static terminal phenotypes, as well as in vivo through virulence studies using conditional strains in an animal model of infection. In addition, the combination of phenotypic and bioinformatic analyses further improves drug target selection from the C. albicans essential gene set, and their respective conditional mutant strains may be directly used as sensitive whole-cell assays for drug screening.

Alleles↗
PubMed2002

Towards safer vectors for the field release of recombinant bacteria.

The prospect of the deliberate environmental release of genetically manipulated microorganisms has given rise to a great deal of polemic. Amongst the rational scientific concerns are those concerned with the fate of the released bacteria, the fate of the recombinant genes that they carry, the selective pressures acting upon them in different environmental situations and the long term effects on the environment and human health. All recombinant DNA is carried by vectors (plasmids, transposons or bacteriophage or remnants of these). Thus the way in which recombinant constructions are made may itself lead to potential biosafety concerns, irrespective of the host bacterium and the recombinant DNA fragment of primary interest. The purpose of the present review is to assess progress in improved vector design aimed at eliminating risks due to the way recombinant vectors are constructed. Improved vector constructions include the avoidance of the use, or removal, of antibiotic resistance genes, the use of defective transposons rather than plasmids in order to reduce horizontal transfer and the development of conditionally lethal suicide systems. More recently, new site-specific recombination systems have permitted transposon vectors to be manipulated following strain construction, but before environmental release, so that virtually all recombinant DNA not directly involved in the release experiment is eliminated. Such bacteria are thus pseudo-wild type in that they contain no heterologous DNA other than the genes of interest.

Bacteria↗
PubMed2002

Genetic tools for pseudomonads, rhizobia, and other gram-negative bacteria.

Gram-negative bacteria are extraordinarily diverse microorganisms that present a wide variety of characteristics worthy of genetic investigation. For historical reasons, the application of recombinant DNA technology to gram-negative bacteria in general has always lagged behind that of E. coli and its close relatives. However, the past 10 years have seen dramatic advances in the development of new tools and vectors for genetic analysis in non-E. coli hosts. Applications include various kinds of genetic manipulation, conjugation, transposition, site-specific recombination, protein secretion, protein purification, cell suicide, microbial ecology, biodegradation, and plant and animal pathogenicity.

Cloning, Molecular↗