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Biomedical subjects

P Williams

Publications and source records attributed to P Williams.

At least 127 records · Page 7Linked to original sources
PubMed1999

Parachuting for charity: is it worth the money? A 5-year audit of parachute injuries in Tayside and the cost to the NHS.

All parachute injuries from two local parachute centres over a 5-year period were analysed. Of 174 patients with injuries of varying severity, 94% were first-time charity-parachutists. The injury rate in charity-parachutists was 11% at an average cost of 3751 Pounds per casualty. Sixty-three percent of casualties who were charity-parachutists required hospital admission, representing a serious injury rate of 7%, at an average cost of 5781 Pounds per patient. The amount raised per person for charity was 30 Pounds. Each pound raised for charity cost the NHS 13.75 Pounds in return. Parachuting for charity costs more money than it raises, carries a high risk of serious personal injury and places a significant burden on health resources.

Accidents, Aviation↗
PubMed1999

Plants genetically modified to produce N-acylhomoserine lactones communicate with bacteria.

N-acylhomoserine lactones (AHLs) play a critical role in plant/microbe interactions. The AHL, N-(3-oxohexanoyl)-L-homoserine lactone (OHHL), induces exoenzymes that degrade the plant cell wall by the pathogenic bacterium Erwinia carotovora. Conversely, the antifungal activity of the biocontrol bacterium Pseudomonas aureofaciens 30-84 is due (at least in part) to phenazine antibiotics whose synthesis is regulated by N-hexanoylhomoserine lactone (HHL). Targeting the product of an AHL synthase gene (yenI) from Yersinia enterocolitica to the chloroplasts of transgenic tobacco plants caused the synthesis in plants of the cognate AHL signaling molecules (OHHL and HHL). The AHLs produced by the transgenic plants were sufficient to induce target gene expression in several recombinant bacterial AHL biosensors and to restore biocontrol activity to an HHL-deficient P. aureofaciens strain. In addition, pathogenicity was restored to an E. carotovora strain rendered avirulent as a consequence of a mutation in the OHHL synthase gene, carI. The ability to generate bacterial quorum-sensing signaling molecules in the plant offers novel opportunities for disease control and for manipulating plant/microbe interactions.

Bacterial Proteins↗
PubMed1999

The Pseudomonas aeruginosa quorum-sensing signal molecule, N-(3-oxododecanoyl)-L-homoserine lactone, inhibits porcine arterial smooth muscle contraction.

The Pseudomonas aeruginosa quorum sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL) has been shown to suppress cytokine production in macrophages. We have examined the effect of OdDHL and related compounds on constrictor tone of porcine blood vessels. OdDHL (1-30 microM) caused a concentration-dependent inhibition of U46619-induced contractions of the coronary artery through a largely endothelium-independent mechanism, but was markedly less effective in the pulmonary artery. Quantitively similar effects to those produced by OdDHL were observed with N-(3-oxododecanoyl)-L-homocysteine thiolactone, a thiolactone derivative, while N-3-oxododecanamide, a lactone-free acyl analogue, possessed 1/3rd the potency as a vasorelaxant. Neither N-butanoyl-L-homoserine lactone nor L-homoserine lactone (up to 30 microM) were active. Our findings indicate that OdDHL inhibits vasoconstrictor tone of both pulmonary and coronary blood vessels from the pig. The vasorelaxant action of OdDHL appears to be primarily determined by the N-acyl chain length, with a minor contribution by the homoserine lactone moiety.

4-Butyrolactone↗
PubMed1999

External oblique aponeurosis nerve entrapment as a cause of groin pain in the athlete.

BACKGROUND: Groin pain in sportsmen is a common management problem. The results of surgical exploration in 25 male athletes presenting with groin pain are described. METHODS: All patients had had failed non-operative management. All groins were explored via an inguinal incision and the patients were reviewed for the presence of pain, function and their own subjective opinion. RESULTS: Nineteen injuries were unilateral and six bilateral. One patient had an occult inguinal hernia and another had a patent processus vaginalis. In the others, defects were found in the external oblique aponeurosis through which neurovascular bundles containing terminal branches of the iliohypogastric nerve passed. These tears were repaired after division of the bundles. The mean time to referral was 29.3 weeks (range 4-79 weeks). After operation no pain or only mild pain was experienced in 28 groins. All had improved function. Twenty of 23 patients described the operation as good or excellent. The mean time to resumption of sporting activities after operation was 11.6 (range 4-20) weeks. CONCLUSION: Athletes' groin pain may be due to nerve entrapment in the external oblique aponeurosis. An awareness of this injury may reduce delays in operating leading to an earlier return to sport.

Adult↗
PubMed1999

An exploration of the application of social role valorization in special hospitals.

The set of ideas known as 'social role valorization' (SRV) has been highly influential in services for some client groups, but has rarely been applied in contexts of security. A framework of questions was designed to assist the application of the theory and principles of SRV in work with patients in special hospitals. Small-scale exercises in its use were introduced to explore the relevance and usefulness of SRV ideas in special hospital work. Evaluation indicated potential usefulness in a variety of contexts, especially when allied to consideration of values issues. No attempt was made in these exercises to incorporate SRV in the operational structures of the hospitals, a task that would require much more thought and work at an organizational level.

Hospitals, Special↗
PubMed1999

Quorum-sensing cross talk: isolation and chemical characterization of cyclic dipeptides from Pseudomonas aeruginosa and other gram-negative bacteria.

In cell-free Pseudomonas aeruginosa culture supernatants, we identified two compounds capable of activating an N-acylhomoserine lactone (AHL) biosensor. Mass spectrometry and NMR spectroscopy revealed that these compounds were not AHLs but the diketopiperazines (DKPs), cyclo(DeltaAla-L-Val) and cyclo(L-Pro-L-Tyr) respectively. These compounds were also found in cell-free supernatants from Proteus mirabilis, Citrobacter freundii and Enterobacter agglomerans [cyclo(DeltaAla-L-Val) only]. Although both DKPs were absent from Pseudomonas fluorescens and Pseudomonas alcaligenes, we isolated, from both pseudomonads, a third DKP, which was chemically characterized as cyclo(L-Phe-L-Pro). Dose-response curves using a LuxR-based AHL biosensor indicated that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) activate the biosensor in a concentration-dependent manner, albeit at much higher concentrations than the natural activator N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). Competition studies showed that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) antagonize the 3-oxo-C6-HSL-mediated induction of bioluminescence, suggesting that these DKPs may compete for the same LuxR-binding site. Similarly, DKPs were found to be capable of activating or antagonizing other LuxR-based quorum-sensing systems, such as the N-butanoylhomoserine lactone-dependent swarming motility of Serratia liquefaciens. Although the physiological role of these DKPs has yet to be established, their activity suggests the existence of cross talk among bacterial signalling systems.

4-Butyrolactone↗
PubMed1999

A hierarchical quorum-sensing system in Yersinia pseudotuberculosis is involved in the regulation of motility and clumping.

In cell-free Yersinia pseudotuberculosis culture supernatants, we have chemically characterized three N-acyl homoserine lactone (AHL) molecules, N-octanoyl homoserine lactone (C8-HSL), N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoyl homoserine lactone (C6-HSL). We have identified, cloned and sequenced two pairs of LuxR/I homologues termed YpsR/I and YtbR/I. In Escherichia coli at 37 degrees C, YpsI and YtbI both synthesize C6-HSL, although YpsI is responsible for 3-oxo-C6-HSL and YtbI for C8-HSL synthesis respectively. However, in a Y. pseudotuberculosis ypsI-negative background, YtbI appears capable of adjusting the AHL profile from all three AHLs at 37 degrees C and 22 degrees C to the absence of 3-oxo-C6-HSL at 28 degrees C. Insertion deletion mutagenesis of ypsR leads to the loss of C8-HSL at 22 degrees C, which suggests that at this temperature the YpsR protein is involved in the hierarchical regulation of the ytbR/I locus. When compared with the parent strain, the ypsR and ypsI mutants exhibit a number of phenotypes, including clumping (ypsR mutant), overexpression of a major flagellin subunit (ypsR mutant) and increased motility (both ypsR and ypsI mutants). The clumping and motility phenotypes are both temperature dependent. These data are consistent with a hierarchical quorum-sensing cascade in Y. pseudotuberculosis that is involved in the regulation of clumping and motility.

4-Butyrolactone↗
PubMed1999

Digital cameras.

Explore the source record for details and available documents.

Data Display↗
PubMed1999

Changing attitudes about schizophrenia.

Research on the effectiveness of short-term education programs in changing societal attitudes about mental illness has been mixed. Education efforts seem to be mediated by characteristics of the program participants. This study determines whether the effects of a specially prepared, semester-long course on severe mental illness are mediated by pre-education knowledge about and contact with severe mental illness. Eighty-three participants who were enrolled in either a course on severe mental illness or general psychology completed the Opinions about Mental Illness Questionnaire before beginning the course and at completion. Research participants also completed a pre-and posttest of knowledge about mental illness and a pretest on their contact with people who have severe mental illness. The education program had positive effects on some attitudes about mental illness. Interestingly, the effects of education group interacted with pre-education knowledge and contact and varied depending on attitude. Participants with more pre-education knowledge and contact were less likely to endorse benevolence attitudes after completing the education program. Participants with more intimate contact showed less improvement in attitudes about social restrictiveness. Implications of these augmentation and ceiling effects are discussed.

Adult↗
PubMed1999

Larsen scoring of digitized X-ray images.

OBJECTIVE: To determine how Larsen scores from digitized X-rays compare to those from film originals. METHODS: A hundred sets of radiographs of patients recruited with early rheumatoid arthritis (RA) were assessed using the Larsen scoring system. Digitized copies of these sets were then viewed on a computer screen and scored according to Larsen in a random order. The quality of the digitized image was also recorded. For each set of X-rays, the signed difference between the score from film and the score from the digitized images was calculated. RESULTS: A total of 95% of the digitized X-ray sets were scored successfully; 5% were not scored due to the images being unreadable. The mean difference between the two sets of scores was -1.2 (95% CI [-2.06, -0.37]). There was no trend in the difference with respect to the mean of the two scores (P>0.1). CONCLUSION: The Larsen scoring of digitized X-ray images has been validated.

Analog-Digital Conversion↗
PubMed1999

Dose-rate effects of ethylene oxide exposure on developmental toxicity.

In risk assessment, evaluating a health effect at a duration of exposure that is untested involves assuming that equivalent multiples of concentration (C) and duration (T) of exposure have the same effect. The limitations of this approach (attributed to F. Haber, Zur Geschichte des Gaskrieges [On the history of gas warfare], in Funf Vortrage aus den Jahren 1920-1923 [Five lectures from the years 1920-1923], 1924, Springer, Berlin, pp. 76-92), have been noted in several studies. The study presented in this paper was designed to specifically look at dose-rate (C x T) effects, and it forms an ideal case study to implement statistical models and to examine the statistical issues in risk assessment. Pregnant female C57BL/6J mice were exposed, on gestational day 7, to ethylene oxide (EtO) via inhalation for 1.5, 3, or 6 h at exposures that result in C x T multiples of 2100 or 2700 ppm-h. EtO was selected because of its short half-life, documented developmental toxicity, and relevance to exposures that occur in occupational settings. Concurrent experiments were run with animals exposed to air for similar periods. Statistical analysis using models developed to assess dose-rate effects revealed significant effects with respect to fetal death and resorptions, malformations, crown-to-rump length, and fetal weight. Animals exposed to short, high exposures of EtO on day 7 of gestation were found to have more adverse effects than animals exposed to the same C x T multiple but at longer, lower exposures. The implication for risk assessment is that applying Haber's Law could potentially lead to an underestimation of risk at a shorter duration of exposure and an overestimation of risk at a longer duration of exposure. Further research, toxicological and statistical, are required to understand the mechanism of the dose-rate effects, and how to incorporate the mechanistic information into the risk assessment decision process.

Administration, Inhalation↗
PubMed1999

Quorum sensing-dependent regulation and blockade of exoprotease production in Aeromonas hydrophila.

In Aeromonas hydrophila, the ahyI gene encodes a protein responsible for the synthesis of the quorum sensing signal N-butanoyl-L-homoserine lactone (C4-HSL). Inactivation of the ahyI gene on the A. hydrophila chromosome abolishes C4-HSL production. The exoprotease activity of A. hydrophila consists of both serine protease and metalloprotease activities; in the ahyI-negative strain, both are substantially reduced but can be restored by the addition of exogenous C4-HSL. In contrast, mutation of the LuxR homolog AhyR results in the loss of both exoprotease activities, which cannot be restored by exogenous C4-HSL. Furthermore, a substantial reduction in the production of exoprotease by the ahyI+ parent strain is obtained by the addition of N-acylhomoserine lactone analogs that have acyl side chains of 10, 12, or 14 carbons. The inclusion of N-(3-oxododecanoyl)-L-homoserine lactone or N-(3-oxotetradecanoyl)-L-homoserine lactone at 10 microM in overnight cultures of A. hydrophila abolishes exoprotease production in azocasein assays and reduces the activity of all the exoprotease species seen in zymograms.

4-Butyrolactone↗
PubMed1999

The staphylococcal transferrin-binding protein is a cell wall glyceraldehyde-3-phosphate dehydrogenase.

Staphylococcus aureus and Staphylococcus epidermidis possess a 42-kDa cell wall transferrin-binding protein (Tpn) which is involved in the acquisition of transferrin-bound iron. To characterize this protein further, cell wall fractions were subjected to two-dimensional sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis blotted, and the N-terminus of Tpn was sequenced. Comparison of the first 20 amino acid residues of Tpn with the protein databases revealed a high degree of homology to the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Analysis of staphylococcal cell wall fractions for GAPDH activity confirmed the presence of a functional enzyme which, like Tpn, is regulated by the availability of iron in the growth medium. To determine whether Tpn is responsible for this GAPDH activity, it was affinity purified with NAD+ agarose. Both S. epidermidis and S. aureus Tpn catalyzed the conversion of glyceraldehyde-3-phosphate to 1,3-diphosphoglycerate. In contrast, Staphylococcus saprophyticus, which lacks a Tpn, has no cell wall-associated GAPDH activity. Native polyacrylamide gel electrophoresis of the affinity-purified Tpn revealed that it was present in the cell wall as a tetramer, consistent with the structures of all known cytoplasmic GAPDHs. Furthermore, the affinity-purified Tpn retained its ability to bind human transferrin both in its native tetrameric and SDS-denatured monomeric forms. Apart from interacting with human transferrin, Tpn, in common with the group A streptococcal cell wall GAPDH, binds human plasmin. Tpn-bound plasmin is enzymatically active and therefore may contribute to the ability of staphylococci to penetrate tissues during infections. These studies demonstrate that the staphylococcal transferrin receptor protein, Tpn, is a multifunctional cell wall GAPDH.

Amino Acid Sequence↗
PubMed1999

Analysis of quorum-sensing-dependent control of rhizosphere-expressed (rhi) genes in Rhizobium leguminosarum bv. viciae.

The rhi genes of Rhizobium leguminosarum biovar viciae are expressed in the rhizosphere and play a role in the interaction with legumes, such as the pea. Previously (K. M. Gray, J. P. Pearson, J. A. Downie, B. E. A. Boboye, and E. P. Greenberg, J. Bacteriol. 178:372-376, 1996) the rhiABC operon had been shown to be regulated by RhiR and to be induced by added N-(3-hydroxy-7-cis-tetradecenoyl)-L-homoserine lactone (3OH, C14:1-HSL). Mutagenesis of a cosmid carrying the rhiABC and rhiR gene region identified a gene (rhiI) that affects the level of rhiA expression. Mutation of rhiI slightly increased the number of nodules formed on the pea. The rhiI gene is (like rhiA) regulated by rhiR in a cell density-dependent manner. RhiI is similar to LuxI and other proteins involved in the synthesis of N-acyl-homoserine lactones (AHLs). Chemical analyses of spent culture supernatants demonstrated that RhiI produces N-(hexanoyl)-L-homoserine lactone (C6-HSL) and N-(octanoyl)-L-homoserine lactone (C8-HSL). Both of these AHLs induced rhiA-lacZ and rhiI-lacZ expression on plasmids introduced into an Agrobacterium strain that produces no AHLs, showing that rhiI is positively regulated by autoinduction. However, in this system no induction of rhiA or rhiI with 3OH,C14:1-HSL was observed. Analysis of the spent culture supernatant of the wild-type R. leguminosarum bv. viciae revealed that at least seven different AHLs are made. Mutation of rhiI decreased the amounts of C6-HSL and C8-HSL but did not block their formation, and in this background the rhiI mutation did not significantly affect the expression levels of the rhiI gene or rhiABC genes or the accumulation of RhiA protein. These observations suggest that there are additional loci involved in AHL production in R. leguminosarum bv. viciae and that they affect rhiI and rhiABC expression. We postulate that the previously observed induction of rhiA by 3OH,C14:1-HSL may be due to an indirect effect caused by induction of other AHL production loci.

4-Butyrolactone↗
PubMed1999

Evaluation of the buccal component of systemic absorption with inhaled fluticasone propionate.

BACKGROUND: Inhaled corticosteroids have dose related systemic effects determined by oral (swallowed or oropharyngeal absorption) and lung bioavailability. A study was undertaken to evaluate the significance of oropharyngeal absorption for fluticasone propionate. METHODS: Sixteen healthy volunteers of mean age 29.3 years were studied using an open randomised, placebo controlled, four way crossover design. Treatments were: (a) fluticasone metered dose inhaler (pMDI) 250 microg, 8 puffs; (b) fluticasone pMDI 250 microg, 8 puffs + mouth rinsing/gargling (water); (c) fluticasone pMDI 250 microg, 8 puffs + mouth rinsing/gargling (charcoal); and (d) placebo pMDI, 8 puffs + mouth rinsing/gargling (water). Overnight (ONUC) and early morning (EMUC) urinary cortisol/creatinine ratios and 8 am serum cortisol (SC) levels were measured. RESULTS: Significant (p<0. 05) suppression of ONUC, EMUC, and SC occurred with each active treatment compared with placebo. The mean values (95% CI for difference from placebo) were: (a) ONUC (nmol/mmol): fluticasone (2. 8, 95% CI 3.6 to 7.9), fluticasone + water (3.1, 95% CI 3.3 to 7.7), fluticasone + charcoal (2.3, 95% CI 4.1 to 8.5); placebo (8.6); (b) EMUC (nmol/mmol): fluticasone (5.6, 95% CI 8.4 to 24.5), fluticasone + water (7.6, 95% CI 6.6 to 22.4); fluticasone + charcoal (5.6, 95% CI 8.7 to 24.5); placebo (22.1). There were no significant differences between active treatments. The numbers of subjects with an overnight urinary cortisol of <20 nmol/10 hours were 0 (placebo), 11 (fluticasone), 12 (fluticasone + water), and 13 (fluticasone + charcoal). CONCLUSIONS: Oropharyngeal absorption of fluticasone does not significantly contribute to its overall systemic bioactivity as assessed by sensitive measures of adrenal suppression. In view of almost complete hepatic first pass inactivation with fluticasone, there is no rationale to employ mouth rinsing to reduce its systemic effects although it may be of value for reducing oral candidiasis.

Absorption↗
PubMed1999

Activation of the NPY Y5 receptor regulates both feeding and energy expenditure.

Intracerebroventricular (ICV) administration of neuropeptide Y (NPY) has been shown to decrease energy expenditure, induce hypothermia, and stimulate food intake. Recent evidence has suggested that the Y5 receptor may be a significant mediator of NPY-stimulated feeding. The present study attempts to further characterize the role of NPY Y5-receptor subtypes in feeding and energy expenditure regulation. Satiated Long-Evans rats with temperature transponders implanted in the interscapular brown adipose tissue (BAT) displayed a dose-dependent decrease in BAT temperature and an increase in food intake after ICV infusion of NPY. Similar effects were induced by ICV administration of peptide analogs of NPY that activate the Y5 receptor, but not by analogs that activate Y1, Y2, or Y4 receptors. Furthermore, ICV infusion of the Y5 selective agonist D-[Trp(32)]-NPY significantly reduced oxygen consumption and energy expenditure of rats as measured by indirect calorimetry. These data suggest that the NPY Y5-receptor subtype not only mediates the feeding response of NPY but also contributes to brown fat temperature and energy expenditure regulation.

Adipose Tissue, Brown↗