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Biomedical subjects

A E Wright

Publications and source records attributed to A E Wright.

At least 19 recordsLinked to original sources
PubMed2006

The role of selective decontamination of the digestive tract in acute stroke.

BACKGROUND: following a stroke, morbidity and mortality is high, with aspiration pneumonia being a common complication. OBJECTIVES: to determine the levels of colonisation by and isolation of aerobic Gram-negative bacteria (AGNB) in acute stroke patients and determine the effect of selective decontamination of the digestive tract (SDD) on oral flora and whether it reduces both morbidity and mortality after an acute stroke. DESIGN: a prospective, randomised, placebo-controlled double blind trial. SETTING: acute stroke assessment units of three hospitals in the northwest of England. SUBJECTS: 203 patients admitted to hospital following a first acute stroke. METHODS: participants were randomised to SDD oral gel or placebo. Swallow was assessed on admission to hospital, and oral swabs were obtained thrice weekly. Demographic and clinical data were recorded. RESULTS: 203 patients (106 males and 97 females) participated, of whom 20 died during their hospitalisation, 19 withdrew and full follow-up was obtained for the remaining 164. A total of 122 AGNB were isolated in 105 samples from 48 patients. Abnormal swallow on admission was found in 58 patients (29%). A total of 34 patients carried a single gram-negative micro-organism that was present on one or more occasions. More than one AGNB was carried in 14 patients, and organisms were significantly more likely to be isolated from the placebo group than the active group during weeks 2 and 3 of treatment (P = 0.034, chi-squared). Seven patients in the placebo group and one in the treatment group developed pneumonia (P = 0.029, Fisher's exact test). CONCLUSIONS: high carriage of and colonisation by AGNB was found within this study, which was reduced by the addition of SDD. Although SDD reduced the presence of both organisms and documented episodes of pneumonia, mortality remained unchanged.

Acute Disease↗
PubMed2001

Evidence that mesoaccumbens dopamine and locomotor responses to nicotine in the rat are influenced by pretreatment dose and strain.

RATIONALE: Sensitisation of the mesoaccumbens dopamine response to nicotine has been implicated in the development of nicotine dependence. This study explored the doses of nicotine that elicit the response in two strains of rats that differ in their baseline levels of activity. METHODS: Male Sprague-Dawley and Lister hooded rats were pretreated with daily subcutaneous injections of (-)-nicotine for 7 days at doses ranging from 0.03 mg/kg to 0.90 mg/kg. Microdialysis studies were performed on day 9 in conscious freely moving rats, placed in an activity box and challenged with 0.4 mg/kg nicotine. RESULTS: The acute administration of nicotine to drug-naive rats stimulated dopamine overflow in the accumbal shell but not the core. Sprague-Dawley rats, pretreated with nicotine (0.03 mg/kg/day and 0.10 mg/kg/day) showed increased basal overflow of dopamine in the accumbal core. Pretreatment with 0.10 mg/kg/day or 0.30 mg/kg/day, but not 0.03 mg/kg/day or 0.90 mg/kg/day, also caused sensitisation of the response to a nicotine challenge on the test day. Sensitisation of the locomotor response to nicotine exhibited a simple dose-response relationship, with the largest sensitisation being observed in animals pretreated with 0.90 mg/kg/day. In Lister hooded rats, pretreatment with nicotine reduced basal dopamine overflow in the accumbal core and did not cause sensitisation to a subsequent challenge with nicotine. CONCLUSIONS: Sensitisation of the mesoaccumbens dopamine response to nicotine is influenced by pre-treatment dose and the strain of rats used. It is not related directly to the expression of sensitised locomotor responses to the drug and, therefore, may be implicated in other psychopharmacological properties of the drug, including dependence.

Animals↗
PubMed2001

Three new peroxides from the sponge Plakinastrella species.

Two new five-membered-ring peroxide acids, plakinic acid F (3) and epiplakinic acid F (4), and a new peroxide-lactone, plakortolide F (5), were isolated from a sponge of the genus Plakinastrella collected from Felicite Island, Seychelles. The structures were elucidated through spectral analysis. The free acids 3 and 4 exhibit moderate antifungal activity against Candida albicans with minimum inhibitory concentrations of 25 micrograms/mL (SDB) and 3.1 micrograms/mL (RPMI) for 3, and 25 micrograms/mL (SDB) and 6.25 micrograms/mL (RPMI) for 4, respectively. Both also showed moderate in vitro inhibition of Aspergillus fumigatus with IC90's of 25 micrograms/mL.

Animals↗
PubMed2000

The putative role of extra-synaptic mesolimbic dopamine in the neurobiology of nicotine dependence.

A majority of habitual tobacco smokers find it very difficult to quit the habit because they become addicted to the nicotine present in tobacco smoke. Nicotine, like other psychostimulant drugs of abuse, increases dopamine release in the principal terminal field of the mesolimbic system, the nucleus accumbens, and there is evidence that this mediates the 'rewarding' properties of the drug, which reinforce its self-administration. This review focuses on the working hypothesis that addiction to nicotine, and other psychostimulant drugs, depends upon their ability to evoke a sustained increase in dopamine release directly into the extracellular space which lies between the cells in the nucleus accumbens where it stimulates extra-synaptic dopamine receptors. It is suggested that increased stimulation of these receptors is associated with increased incentive learning or the attribution of increased incentive salience to the cues associated with acquisition and delivery of the drug. The hypothesis proposes that these cues can become conditioned reinforcers of drug-taking behaviour. The receptors, which mediate the effects of nicotine on mesoaccumbens dopamine neurones, are desensitised by sustained exposure to nicotine at concentrations commonly found in the plasma of habitual smokers. It is proposed that, at times when the plasma nicotine concentration is sufficiently high to cause desensitisation of the receptors, tobacco smoking is maintained by the conditioned reinforcers present in the tobacco smoke. The hypothesis predicts, therefore, that conditioned reinforcement may play a more important role in the addiction to tobacco than for most other addictive behaviours. As a result, studies with nicotine have the potential to contribute to our understanding of the neurobiology of addiction which cannot easily be explored using drugs, such as cocaine and amphetamine, which invariably increase dopamine overflow in the forebrain.

Animals↗
PubMed1999

Secobatzellines A and B, two new enzyme inhibitors from a deep-water Caribbean sponge of the genus Batzella.

Secobatzelline A (1), a new batzelline natural analogue, and secobatzelline B (2), a likely artifact formed during the isolation procedure, have been isolated from a deep-water marine sponge of the genus Batzella. Secobatzellines A and B inhibited the phosphatase activity of calcineurin, and secobatzelline A inhibited the peptidase activity of CPP32. Both compounds showed in vitro cytotoxicity against P-388 and A-549 cell lines. The isolation and structure elucidation of secobatzellines A (1) and B (2) are described.

Alkaloids↗
PubMed1998

The 3' untranslated region of manganese superoxide dismutase RNA contains a translational enhancer element.

A redox-sensitive protein that binds to the 3' untranslated region (UTR) of manganese superoxide dismutase (MnSOD) RNA has been described previously [Fazzone, H., Wangner, A., and Clerch, L. B. (1993) J. Clin. Invest. 92, 1278-1281; Chung, D. J., and Clerch, L. B. (1997) Am. J. Physiol. 16, L714-L719]. In the present study, cross-competition gel retardation and RNase H assays were used to identify a 41-base region located 111 bases downstream of the stop codon as the 3' UTR cis element involved in protein binding. The base sequence of this region is approximately 75% conserved among the 3' UTRs of rat, mouse, cow, and human MnSOD mRNAs at approximately the same distance downstream of the stop codon. The role of this protein-binding region in RNA translation was assessed in an in vitro rabbit reticulocyte lysate system. Translation of MnSOD RNA from which the 3' UTR element was deleted decreased 60% compared with translation of MnSOD RNA containing the 3' UTR cis element. In the presence of a specific competitor oligoribonucleotide that inhibits MnSOD RNA protein-binding activity, translation of MnSOD RNA containing the 3' UTR was decreased by 65%. Thus, both the cis element and RNA protein-binding activity were required for more efficient translation of the MnSOD. An analysis of ribosomal profiles suggests the MnSOD RNA-binding protein participates in the formation of the translation initiation complex. When MnSOD RNA-binding activity was inhibited, initiation complex formation was decreased by 50%. From the data obtained in this study, we propose that the 3' UTR cis element of MnSOD through its interaction with MnSOD RNA-binding protein may function as a translational enhancer.

3' Untranslated Regions↗
PubMed1997

An intronic polymorphism in the presenilin-1 gene does not influence the amount or molecular form of the amyloid beta protein deposited in Alzheimer's disease.

The frequency of the allele-1 polymorphism in intron 8 of the presenilin-1 (PS-1) gene, and the proportion of individuals homozygous in this respect, was investigated in 57 patients with autopsy verified Alzheimer's disease (AD). In 33 of these patients the amount of amyloid beta protein (A beta) was compared across the three PS-1 genotype groups (1/1, 1/2, 2/2). No excess of the allele-1 was detected in these patients with confirmed AD and no variations in the extent of A beta deposition, as either A beta 40 or A beta 42, in terms of plaque number or percentage area of tissue occupied, were found. We conclude that this intronic PS-1 polymorphism does not influence the pathological phenotype of AD, at least as far as A beta deposition is concerned.

Aged↗
PubMed1996

High dose rate intracoronary radiation for inhibition of neointimal formation in the stented and balloon-injured porcine models of restenosis: angiographic, morphometric, and histopathologic analyses.

PURPOSE: We examined the effects of intracoronary irradiation delivered at a high dose rate on neointimal hyperplasia after injury induced by two methods: balloon overstretch injury, and stent implantation in a porcine model of coronary restenosis. METHODS AND MATERIALS: In 34 Hanford miniature swine, a segment of each coronary artery was targeted for injury and treatment. The artery segments were treated with 192Ir at doses of 10 Gy over 4 min (eight animals), 15 Gy over 6 min (nine animals), 25 Gy over 10 min (nine animals) or control (simulation wire only; eight animals). The treated segments were subjected to stent implantation (left anterior descending and right coronary artery) or balloon overstretch (circumflex) injury. Twenty-eight days later, repeat coronary angiography and sacrifice were done. Quantitative coronary angiography, morphometry, and extensive histopathologic analyses were carried out in a blinded fashion. RESULTS: The change in minimal lumen diameter from postinjury to presacrifice in the stent-injured left anterior descending was -0.79 +/- 0.34 (mean: +/- SD) mm in the control group, compared to -0.43 +/- 0.35 mm in the 15 Gy (p = 0.04) and -0.21 +/- 0.50 mm in the 25 Gy (p = 0.01) groups; and in the balloon-injured circumflex was -0.31 +/- 0.22 mm in the control group compared to -0.03 +/- 0.18 mm in the 10 Gy (p = 0.05) and 0.00 +/- 0.33 in the 15 Gy (p = 0.01) groups. Percent area stenosis in the left anterior descending was 36 +/- 9% in the control group compared to 18 +/- 12% in the 15 Gy (p = 0.003) and 11 +/- 11% in the 25 Gy (p < 0.001) groups; and in the circumflex was 16 +/- 10% in the control groups, compared to 5 +/- 5% in the 15 Gy (p = 0.02) and 2 +/- 2% in the 25 Gy (p = 0.009) groups. Histopathology showed a striking reduction in the amount of neointima in the irradiated arteries compared with control vessels. Other radiation effects were stromal fibrin exudate, thinning of the media, and adventitial fibrosis and leukocyte infiltration in the radiated arterial segments. CONCLUSIONS: High dose rate intracoronary irradiation with 192Ir effectively inhibits intimal proliferation after stent-induced as well as balloon-overstretch injury. This shorter treatment time (4 to 10 min) may provide a clinically practical approach to the prevention of restenosis after angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1996

Characterization of an interleukin 6 cytokine family antagonist protein from a marine sponge, Callyspongia sp.

An inhibitor of IL-6 binding to the human hepatoma line HepG2 and myeloma cell line U266 was identified in a saline extract of the marine sponge, Callyspongia sp. Functional activity, measured through the increase in haptoglobin production by HepG2 cells stimulated with IL-6, could be strongly inhibited by the extract. Similarly, IL-6-induced production of IgM by the B cell line SKW6.4 was substantially reduced. In neither cell line was there evidence of toxicity produced by the extract. Other sponges of the Callyspongia species were found to contain analogous activity. The activity was destroyed by trypsin treatment or boiling of the extract, suggesting that the inhibition is due to a protein. When the binding of IL-6 to its receptor complex was dissected in vitro, inhibition of binding of IL-6 to soluble receptor by the extract was not detected, but binding of the IL-6-sIL-6R complex to soluble gp130 was inhibited in a dose-dependent fashion. This was borne out in cellular assays since the extract inhibited activation of HepG2 cells stimulated with oncostatin M or leukemia inhibitory factor, cytokines which also use gp130 for signal transduction. These results suggest that the Callyspongia extract contains a protein which blocks the interaction of the IL-6 family of cytokines with their signal transduction moiety, gp130. Elucidation of the structure and mode of action of such a protein would be helpful in designing gp130 antagonists to inhibit the functions of this cytokine family, overproduction of which has been associated with cancer and pathologies of autoimmune disease and AIDS.

Animals↗
PubMed1996

Lung manganese superoxide dismutase protein expression increases in the baboon model of bronchopulmonary dysplasia and is regulated at a posttranscriptional level.

The expression of lung manganese superoxide dismutase (MnSOD) mRNA and protein were examined in a premature baboon model of hyperoxia-induced bronchopulmonary dysplasia (BPD) and BPD superimposed with bacterial infection. When 140-d gestation baboons were delivered by hysterotomy and treated for 16 d with appropriate ventilatory and oxygen support (pro re nada controls), there was an increase in both MnSOD mRNA and protein compared with 140-d or 156-d gestation, nonventilated controls. The concentration of MnSOD protein was also elevated when the prematurely delivered baboons were ventilated with a high fraction of inspired O2 to produce a primate homolog of BPD, but there was a significant decrease in the concentration of MnSOD mRNA in BPD animals compared with pro re nada controls. In the lungs of premature baboons in which Escherichia coli infection was superimposed on hyperoxia-induced BPD, MnSOD mRNA was diminished to approximately the same extent as in BPD alone, but MnSOD protein was significantly increased compared with all other groups. Taken together these data indicate that the premature baboon is capable of mounting an antioxidant response and that increased MnSOD protein expression in BPD and BPD-infected premature baboons is regulated, at least in part, at a posttranscriptional level.

Animals↗
PubMed1995

Bis(sulfato)-cyclosiphonodictyol A, a new disulfated sesquiterpene-hydroquinone from a deep water collection of the Marine sponge Siphonodictyon coralliphagum.

A new compound, bis(sulfato)-cyclosiphonodictyol A [1], which inhibits the binding of [3H]-LTB4 to intact human neutrophils with an IC50 value of 44 microM, was isolated from the sponge Siphonodictyon coralliphagum. The sponge was collected using the Johnson-Sea-Link manned submersible at a depth of 195 feet in the Bahamas. The compound was isolated via reversed-phase chromatography and its structure determined spectroscopically. To the best of our knowledge, 1 is the first marine-derived compound with two aromatic sulfate ester functionalities, and is also the first in the siphonodictyal series to contain an oxepane functionality.

Animals↗
PubMed1995

Two possible mechanisms for survival and initiation of Murray Valley encephalitis virus activity in the Kimberley region of Western Australia.

Two possible mechanisms are described for the initiation of Murray Valley encephalitis (MVE) virus activity in arid, epizootic regions of tropical Australia. Virus isolations were made from mosquitoes trapped shortly after the first heavy wet season rains and flooding in the east Kimberley, which followed approximately nine months of drought. A number of isolates of MVE virus were obtained, including isolates from pools of blood-engorged Culex annulirostris mosquitoes and from a single pool of male Aedes tremulus mosquitoes. The results strongly suggested that MVE virus activity was due both to its introduction in viremic vertebrate hosts, from which first-generation mosquitoes became infected following blood meals, and also to reactivation of vertically transmitted virus from desiccation-resistant eggs of Ae. tremulus. Both mechanisms are discussed with respect to environmental conditions.

Aedes↗
PubMed1994

The effect of an in-flight, emergency training program on crew confidence.

INTRODUCTION: Despite some progress, the air medical transport profession continues to experience widely publicized accidents that result in injuries and death to crew members and patients. An air medical crew member's experience, training and confidence may affect his or her ability to deal effectively with an in-flight emergency, and may also affect his or her behavior before and after the emergency. SETTING: A hospital-based, rural rotor- and fixed-wing program flying approximately 890 flights per year. Seventy-seven percent of these flights are interfacility. METHODS: A pretraining survey evaluated the experiences of air medical crew members and pilots. A 20-question assessment tool based on a 5-point Likert scale evaluated how confident the individuals were in their ability to react to in-flight emergencies. An extensive in-flight emergency training program was then conducted. Personnel were asked to complete the same questionnaire one month and six months after the training. RESULTS: On the pretraining questionnaire, flight crew members with neither prior training nor actual experience in in-flight emergencies showed the lowest level of confidence. Those with prior training, actual in-flight emergency experience or both, responded with higher levels of confidence. The mean confidence scores of the study participants increased from 82 pretraining to 89 at one month post-training and remained at the increased level six months after training. CONCLUSIONS: A training program focusing on in-flight, aircraft-related emergencies can increase the crew's confidence during such situations. This increase in confidence is most noticeable in those without previous training or experience and is maintained for at least six months. Several other benefits occur from the training program.

Accidents, Aviation↗
PubMed1993

Sesquiterpene-derived metabolites from the deep water marine sponge Poecillastra sollasi.

Six sesquiterpene-derived compounds, 1-6, which we call sollasins a-f, have been isolated from a deep water specimen of the sponge Poecillastra sollasi. The structures were elucidated by comparison of spectral data to related metabolites and confirmed using spectroscopic methods. The compounds inhibit the growth of the pathogenic fungi Candida albicans and Cryptococcus neoformans and the P-388 and A-549 tumor cell lines. Compounds 3 and 4 show weak inhibition of binding of [125I] angiotensin II to rat aorta smooth muscle cell membranes.

Angiotensin II↗