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Biomedical subjects

B Hughes

Publications and source records attributed to B Hughes.

At least 37 records · Page 2Linked to original sources
PubMed1997

Optimized oligonucleotides for the differentiation of Prevotella intermedia and Prevotella nigrescens.

The gram-negative, anaerobic bacterium Prevotella intermedia plays an important role in the progression of periodontitis, whereas the etiological role of the closely related but phenotypically indistinguishable species Prevotella nigrescens is controversial. To differentiate between these species properly, 16S rDNA/RNA directed, computer-optimized oligonucleotides were designed and tested with 26 P. intermedia, 26 P. nigrescens and a number of closely and more distantly related strains. The oligonucleotides were used as primers in a polymerase chain reaction and could be demonstrated to be species specific with a detection limit of 50 bacterial cells, which could also be detected when diluted 1:10(5) with different plaque bacteria. In addition, the described oligonucleotides were digoxigenin-labeled at the 3' end and used as DNA probes in a dot blot hybridization assay. This assay, although slightly less sensitive than the polymerase chain reaction-based method, gave species-specific reactions and also allowed (semi-)quantification of bacterial cells in clinical specimens.

Bacterial Typing Techniques↗
PubMed1996

Effects of theophylline and rolipram on antigen-induced airway responses in neonatally immunized rabbits.

1. The effects of the xanthine, theophylline, a non-selective phosphodiesterase (PDE) inhibitor, and the phosphodiesterase type 4 (PDE 4) inhibitor, rolipram, were evaluated in a model of antigen-induced airway responses in the allergic rabbit. 2. Adult litter-matched NZW rabbits (2.5-3.9 kg), immunized within 24 h of birth with Alternaria tenuis antigen, were pretreated twice daily for 3 days with theophylline (3 mg kg-1, i.p) or rolipram (1 mg kg-1, i.p) prior to antigen challenge (Alternaria tenuis). For each drug-treated group, a parallel group of rabbits were pretreated with the appropriate vehicle. In all groups airway responsiveness to inhaled histamine and bronchoalveolar lavage (BAL) was performed 24 h before and after antigen-challenge. 3. Basal lung function in terms of resistance (RL, cmH2O 1(-1)s-1) and dynamic compliance (Cdyn, ml cmH2O-1) were unaltered by pretreatment with theophylline or rolipram compared to their respective vehicles 24 h prior to or post antigen challenge. 4. The acute bronchoconstriction induced by inhaled Alternaria tenuis aerosol was unaffected by pretreatment with theophylline or rolipram. 5. Airway hyperresponsiveness to inhaled histamine was indicated by reduced RL PC50 (2.4-3.5 fold) and Cdyn PC35 (2.5-2.6 fold) values 24 h after antigen challenge. Treatment with rolipram, but not theophylline, prevented the increase in responsiveness to inhaled histamine 24 h after antigen challenge. 6. Total cells per ml of BAL fluid increased 24 h after antigen challenge due to the recruitment of neutrophils and eosinophils. Antigen-induced increases in pulmonary neutrophils were unaffected; however, eosinophils were reduced 57.5% in theophylline and 82% in rolipram-treated rabbits. 7. Inhalation of Alternaria tenuis aerosol elicits an acute bronchoconstriction, followed 24 h later by an increased responsiveness to inhaled histamine and pulmonary neutrophil and eosinophil recruitment in the immunized rabbit. With the dosing regimes used, both rolipram and theophylline inhibited eosinophil recruitment, whilst only rolipram prevented the development of airway hyperresponsiveness. Neither agent inhibited the acute bronchoconstriction due to inhaled antigen.

Airway Resistance↗
PubMed1996

The inhibition of antigen-induced eosinophilia and bronchoconstriction by CDP840, a novel stereo-selective inhibitor of phosphodiesterase type 4.

1. The novel tri-aryl ethane CDP840, is a potent and selective inhibitor of cyclic AMP phosphodiesterase type 4 (PDE 4) extracted from tissues or recombinant PDE 4 isoforms expressed in yeast (IC50S: 4-45 nM). CDP840 is stereo-selective since its S enantiomer (CT 1731) is 10-50 times less active against all forms of PDE 4 tested while both enantiomers are inactive (IC50S: > 100 microM) against PDE types 1, 2, 3 and 5. 2. Oral administration of CDP840 caused a dose-dependent reduction of interleukin-5 (IL-5)-induced pleural eosinophilia in rats (ED50 = 0.03 mg kg-1). The eosinophils in pleural exudates from CDP840-treated animals contained higher levels of eosinophil peroxidase (EPO) than cells from control animals, suggesting a stabilizing effect on eosinophil degranulation. CDP840 was approximately equi-active with the steroid dexamethasone in this model and was 10-100 times more potent than the known PDE 4-selective inhibitors rolipram and RP73401. The activity of CDP840 was not influenced by adrenalectomy, beta-sympathomimetics or beta-sympatholytics. 3. Antigen-induced pulmonary eosinophilia in sensitized guinea-pigs was reduced dose-dependently by CDP840 (0.01-1 mg kg-1, i.p.) and intracellular EPO levels were significantly higher. CDP840 was more potent in these activities than CT1731 or rolipram and comparable in potency to RP73401. 4. Rolipram or CDP840 were less active than dexamethasone in preventing neutrophil accumulation, or exudate formation in carrageenan-induced pleurisy in rats and thus do not exhibit general anti-inflammatory activity. 5. In sensitized guinea-pigs, aerosols of the antigen ovalbumin caused a dose-dependent bronchoconstriction demonstrated by an increase in pulmonary inflation pressure. Administration of CDP840 (0.001-1.0 mg kg-1, i.p.), 1 h before antigen challenge, resulted in dose-dependent reduction in response to antigen. This activity was not due to bronchodilatation since higher doses of CDP840 (3 mg kg-1) did not significantly change the bronchoconstrictor response to histamine. Rolipram was approximately 10 times less active than CDP840 in preventing antigen-induced bronchoconstriction. 6. These results confirm the observations that selective PDE 4 inhibitors reduce antigen-induced bronchoconstriction and pulmonary eosinophilic inflammation. CDP840 is more potent than rolipram in inhibiting native or recombinant PDE 4. Unlike the recently described potent PDE 4 inhibitor RP73401, CDP840 is more active than rolipram in the rat IL-5 model following oral administration. The novel series of tri-aryl ethanes, of which CDP840 is the lead compound, could be the basis of an orally active prophylactic treatment for human asthma.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1996

Inhibition of bronchospasm and ozone-induced airway hyperresponsiveness in the guinea-pig by CDP840, a novel phosphodiesterase type 4 inhibitor.

1. The activity of CDP840, a novel, potent and selective cyclic nucleotide phosphodiesterase type 4 (PDE 4) inhibitor, was evaluated in guinea-pig models (in vitro and in vivo) of bronchospasm, ozone-induced airway hyperresponsiveness (AHR) and non-cholinergic bronchoconstriction. Comparisons were made with (i) other PDE 4 inhibitors: CT1731 (S-enantiomer of CDP840), rolipram, RP73401 and (ii) the clinically used agents salbutamol and theophylline. 2. CDP840 relaxed isolated trachea, under basal tone (EC50 4.5 +/- 1.1 microM) being 17 fold less potent than rolipram (EC50 0.26 +/- 0.13 microM) but attaining the same Emax (83 +/- 6% of the response to 300 microM papaverine). 3. CDP840 relaxed tracheae pre-contracted with carbachol (IC25 39 +/- 9 microM) and histamine (IC25 4 +/- 1 microM) producing monophasic curves. Stereoselectivity was not observed with CT1731 against either carbachol (IC25 33 +/- 11 microM) or histamine (IC25 17 +/- 10 microM). Aminophylline was 1.6 fold (carbachol) and 11 fold (histamine) less potent than CDP840. Rolipram and RP73401 produced tri-phasic relaxation curves but were of similar potency (at the IC25 level) to CDP840 against carbachol (rolipram 18 +/- 5 microM, RP73401 39 +/- 1 microM) whereas against histamine they were approximately 20 fold more potent (rolipram 0.2 +/- 0.1 microM, RP73401 0.2 +/- 0.1 microM). In producing > 30% (carbachol) and > 60% (histamine) relaxation these inhibitors had similar potency and were poor compared to salbutamol. 4. Pre-incubation with CDP840 (10 microM) did not antagonize histamine-induced contraction of isolated trachea; however, it did cause a slight potentiation of the subsequent relaxation to salbutamol (IC50 23 +/- 1 to 15 +/- 2 nM). 5. Pretreatment (1 h) with either CDP840 (1 mg kg-1, i.p. or 3 mg kg-1, i.v.) or rolipram (1 mg kg-1, i.p.) did not bronchodilate or antagonize bronchospasm due to inhaled histamine in anaesthetized, ventilated guinea-pigs. Salbutamol (1 mg kg-1, i.p.) did not bronchodilate but caused a parallel 7 fold rightward shift in the histamine dose-response curve. 6. Stimulation of the vagus nerve in the presence of atropine resulted in a frequency-related bronchoconstriction. CDP840 and rolipram (i.v.) inhibited the response being approximately equipotent (EC50 approximately 10 micrograms kg-1). Neither drug inhibited bronchospasm to inhaled substance P. 7. CDP840 (1-10 micrograms kg-1 i.p.) dose relatedly inhibited ozone-induced bronchoconstriction. CT1731 (1 mg kg-1), rolipram (1 mg kg-1), RP73401 (10 micrograms kg-1) and aminophylline (10 mg kg-1) had no effect. Ozone-induced AHR to inhaled histamine was inhibited by CDP840 in a dose-related manner, 10 micrograms kg-1 abolishing the AHR. This effect was stereoselective as CT1731 was approximately 30 fold less potent than CDP840. Rolipram was approximately 100 fold less potent and RP73401 and aminophylline had no effect. CDP840 was orally active being approximately 10 fold less potent compared to i.p. administration. 8. CDP840 is a poor spasmolytic and anti-spasmogenic agent in response to exogenous mediators; however, it potently inhibits vagally mediated non-cholinergic bronchoconstriction and ozone-induced AHR to histamine. It is possible that regulation of cyclic AMP by PDE 4 contributes to neuronal sensitivity in the airways. Furthermore, CDP840 may suppress AHR without being an overt bronchodilator. Such a profile of activity may have therapeutic benefit in airways diseases such as asthma.

Analysis of Variance↗
PubMed1996

Effect of the glucocorticosteroid budesonide and a novel phosphodiesterase type 4 inhibitor CDP840 on antigen-induced airway responses in neonatally immunised rabbits.

1. The effects of the inhaled corticosteroid budesonide and a novel PDE 4 inhibitor CDP840 given systematically, were evaluated in a model of antigen-induced airway inflammation in the rabbit. 2. Adult litter-matched NZW rabbits (2.4-3.5 kg) immunised within 24 h of birth with Alternaria tenuis antigen were pretreated with budesonide (total dose 100 micrograms, inhaled over 2 days) or CDP840 (total dose 7 mg kg-1, i.p. over 3 days), before antigen challenge. For each drug-treated group a parallel group of rabbits was pretreated with the appropriate vehicle. In all groups airway responsiveness to inhaled histamine was assessed and bronchoalveolar lavage (BAL) performed 24 h before and after antigen challenge. 3. Basal lung function in terms of total lung resistance (RL; cmH2O l 1s-1) and dynamic compliance (Cdyn; ml cmH2O-1) were unaltered by pretreatment with budesonide or CDP840 compared to their respective vehicles 24 h before or after antigen challenge. 4. The RL component of the acute bronchoconstriction induced by inhaled Alternaria tenuis aerosol was unaffected by pretreatment with budesonide. However, budesonide prevented the fall in Cdyn due to antigen. Treatment with CDP840 significantly reduced antigen-induced acute bronchoconstriction in terms of both RL and Cdyn. 5. Airway hyperresponsiveness (AHR) to inhaled histamine was indicated by reduced RL PC50 (2.4-4.5 fold) and Cdyn PC35 (2.1-3.9 fold) values 24 h after antigen challenge. Treatment with either budesonide or CDP840 abolished the antigen-induced increase in responsiveness to inhaled histamine. 6. Total cells recovered per ml of BAL fluid increased 24 h after antigen challenge. Antigen-induced pulmonary eosinophilia was reduced (93%) in budesonide and (85%) in CDP840 treated rabbits. Antigen-induced increases in neutrophil numbers were reduced (76%) with budesonide but not CDP840 pretreatment. 7. Inhalation of Alternaria tenuis aerosol elicited an acute bronchoconstriction, followed 24 hours later by an increased responsiveness to inhaled histamine and pulmonary neutrophil and eosinophil recruitment. CDP840 was more effective than budesonide in preventing the antigen-induced increase in total lung resistance (RL); however, both drugs prevented the antigen-induced reduction in dynamic compliance (Cdyn). CDP840 and budesonide also prevented antigen-induced AHR and eosinophilia in the immunised rabbit.

Administration, Inhalation↗
PubMed1996

Evaluation of anti-viral filters.

The purification processes used to prepare medicines from human and animal cell lines provide one of the major opportunities for virus risk reduction. The purification process can be validated for its ability to remove a range of viruses and can be shown to provide a significant barrier to the transmission of viruses from cell substrates and raw materials to the patient. Ultrafiltration membranes which are manufactured with extremely tight control on pore size distribution can remove a broad spectrum of viruses with high efficiency. A scheme is described for the evaluation of anti-viral filters and the results from evaluation of two filters are presented. The experiments carried out with ultrafiltration membranes suggest that they can provide significant additional virus risk reduction factors for biopharmaceuticals.

Animals↗
PubMed1995

Invasive pneumococcal disease in central Australia.

Invasive pneumococcal disease remains a major problem in certain groups of people. We undertook a hospital-based review of all cases of invasive pneumococcal disease in central Australia over a 2-year period. We observed 79 cases of invasive disease in 78 patients. The incidence of invasive pneumococcal disease was highest in Aborigines under 5 years of age (1,025 cases per 100,000 population per year). The relative risk for Aborigines compared with non-Aborigines was 31.6 (95% CI, 12.8-78.1). Pneumonia was the commonest disease observed (82% of patients). Eight patients died (10.1%), and all of these patients had identifiable risk factors for pneumococcal disease. Serotyping showed that all except two isolates were covered by the existing 23-valent pneumococcal vaccine. These data reveal that Aborigines in central Australia have the highest reported rate of invasive pneumococcal disease in the world. A vaccination program in central Australia should decrease admissions and deaths due to pneumococcal disease.

Adolescent↗
PubMed1994

The in vivo and in vitro effects of antibodies against rabbit beta 2-integrins.

Beta 2-integrins play a crucial role in the development of an inflammatory response. In ours study, Abs have been used to investigate the role of individual members of this family of adhesion molecules in both in vivo and in vitro assays. An Ab against rabbit LFA-1 effectively inhibited the adhesion of rabbit polymorphonuclear leukocytes to rabbit endothelial cells in culture and was also effective in blocking cell recruitment to the peritoneum and vascular leakage at dermal sites of inflammation. An Ab that inhibited rabbit complement receptor type 3 function in vitro failed to inhibit cell recruitment to the peritoneum or vascular leakage in response to intradermal FMLP. Histologic studies suggested that the anti-complement receptor type 3 Ab may have modified the cell migration process.

Animals↗
PubMed1994

Modulations of membrane potential oscillations with drive, calcium overload, ryanodine, and caffeine.

The objective of this study is to determine the conditions that generate overdrive excitation and overdrive suppression in canine cardiac Purkinje tissue superfused in vitro. Drive-induced (3 Hz) perturbations in the membrane potential of a calcium overloaded (induced by strophanthidin) Purkinje fiber (from a canine heart) were differently modulated by caffeine and ryanodine. Whereas the postdrive oscillations in the membrane potential Vos (single or multiple oscillations in the diastole of the action potential) and/or spontaneous rate (postdrive suppression or postdrive excitation [PDE]) depended on the concentration of strophanthidin (PDE occurred at 2.5 x 10(-7) M, and Vos were seen variably at several concentrations), caffeine (2-3 mM) in the presence of a lower concentration of strophanthidin (1.25 x 10(-7) M) induced PDE. At these lower concentrations, either drug administered alone only induced Vos. On the contrary, the characteristic effects of ryanodine (10(-8) M) in the presence of strophanthidin (2.5 x 10(-7) M) were either a consistent postdrive suppression immediately or the induction of a pronounced afterdepolarization ([AD] a depolarization following the repolarization of the action potential) whose amplitude decreased with time and suppression. At higher concentrations of ryanodine (10(-5) M-10(-6) M) in a calcium overloaded tissue (strophanthidin, 1.25 x 10(-7) M) overdrive induced a pronounced AD in most cases, with subsequent depolarization and cessation of activity in less than 20 minutes. Ryanodine alone caused suppression of postdrive diastolic potential at lower concentrations (10(-9) M-10(-8) M), a pronounced AD (amplitude diminished with later drives), and suppression at higher concentrations (10(-6) M-10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1994

Dextrose-, adenosine- and magnesium-induced protective actions during anoxia and reperfusion in canine Purkinje tissue.

1. The effects of dextrose, magnesium (Mg) and adenosine on membrane potential and force of contraction were studied in driven and overdriven canine cardiac Purkinje tissue. 2. Dextrose (50 mmol/L) and adenosine (4-6 mmol/L) both showed protective action (the latter to a lesser extent) against simulated anoxia and reperfusion-induced arrhythmias, increased force of contraction transiently on reperfusion, and the former sustained the increase in force to a lower level as long as it was in the superfusing solution. 3. Dextrose (50 mmol/L) and Mg (5 mmol/L) restored overdrive-induced hyperpolarization during simulated anoxia. Adenosine was largely ineffective. 4. It was concluded that dextrose and adenosine (to a lesser extent) protect against arrhythmias by replenishing the critical intracellular pool of ATP which controls membrane transport of electrolytes such as K and Ca. Restoration of Na-K ATPase activity alone (as in the case of high Mg concentrations) is not sufficient to prevent arrhythmias.

Action Potentials↗
PubMed1994

Gene therapy for cystic fibrosis in humans by liposome-mediated DNA transfer: the production of resources and the regulatory process.

The number of clinical trials using gene transfer technology, either active or under discussion, is increasing rapidly. However, little information is available describing the regulatory procedures or safety specifications that must be considered before initiation of such trials in Europe. We describe the procedure used by our group to produce resources for the first stage of a phase I trial of liposome-mediated gene therapy for cystic fibrosis. The current lack of written and co-ordinated guidance from the numerous interested regulatory agencies within the UK and Europe makes determination of the appropriate safety specifications and procedures for these novel trials difficult, as does the fact that some new agencies (such as the Genetic Therapy Advisory Committee in the UK) and some which are unfamiliar with clinical trials (such as the Department of the Environment) are involved as well as the Medicines Control Agency. In addition, we estimate that the realistic cost of these trials, which in many cases will have to be covered from research budgets provided by government agencies or medical charities, could lead to delays in the clinical application of this important new therapeutic strategy.

Base Sequence↗
PubMed1993

The lipolytic effect of beta 1- and beta 2-adrenoceptor activation in healthy human volunteers.

1. We investigated the effect of activation beta 1- and beta 2-adrenoceptors on the process of lipolysis in human volunteers. Ten male subjects underwent a single-blind randomized cross-over trial using infusions of terbutaline (a specific beta 2-adrenoceptor agonist), xamoterol (a partial beta 1-agonist with beta 2-adrenoceptor blocking activity) and saline (placebo control). The effect of these infusions on plasma potassium, glucose, free fatty acids (FFA) (total and individual) and insulin levels was studied. 2. Terbutaline infusion induced a significant rise in plasma glucose and a fall in plasma potassium in keeping with its beta 2-adrenoceptor stimulant properties. Xamoterol infusion had no significant effect on these values. Terbutaline infusion caused a greater rise in total and individual FFA than xamoterol, but both effects were significantly different from placebo. 3. The possible reasons for these results and their implications on the beta-adrenergic control of lipolysis are discussed.

Adult↗
PubMed1993

Seasonal allergic symptoms and their relation to pollen exposure in south-east France.

In order to evaluate the relationship between pollen exposure and prevalence of allergic respiratory symptoms, we performed a cross-sectional epidemiological study in 2 areas with contrasted exposure to cypress and grass pollens. The study population consisted of 5427 subjects 18 to 65-years-old representative of the general population. All answered an abridged version of the 1978 ATS questionnaire and a sample had a skin test evaluation including grass and cypress pollens. Prevalence of hay fever symptoms was equal to 31.5% and 14.1%, respectively, in exposed and less exposed community (P < 0.001). Prevalence of hay fever symptoms together with a positive skin test to pollen was also significantly higher in the exposed (13.6%) vs less exposed community (5.5%, P < 0.001). In contrast, overall prevalence of asthma was equal to 4.5% and 3.4%, respectively. Prevalence of asthma with positive skin tests was also not statistically significant, equal to 2.5% and 1.9%, respectively. Thus, high exposure to pollen is a risk factor for developing hay fever but not asthma.

Adolescent↗
PubMed1993

A comparison of the beta 1-selectivity of conventional metoprolol and metoprolol CR during exercise in healthy volunteers.

This paper reports on a randomized double-blind crossover study to compare the effects of daily treatment with 100 mg conventional metoprolol (M100), 50 or 100 mg slow-release metoprolol CR (CR50, CR100) and placebo on the response to treadmill walking exercise in 12 healthy volunteers. Twenty minutes of exercise was undertaken at 1.5 h post-dose (Ex1) and again at 4 h (Ex2). During Ex1 all metoprolol preparations caused a reduction in the exercise-induced increase in heart rate when compared to placebo (P < 0.001). The exercise-induced increase in plasma glycerol, an indicator of lipolysis, was diminished by all metoprolol preparations but to a greater extent by M100 (P < 0.05). Rises in plasma ammonia were used to assess the net degradation of energy-rich adenine nucleotides by skeletal muscle during exercise. When compared to placebo, a significant elevation in plasma ammonia was seen only during exercise with M100 (P < 0.05). The perceived exertion at the end of exercise was also greatest on conventional metoprolol. The differences between the effects of conventional and CR formulations of metoprolol were less when exercise was repeated 4 h post dosing. We conclude that metoprolol CR may offer advantages over the conventional preparation, in subjects regularly engaging in exercise, by reducing the metabolic stress imposed upon skeletal muscle.

Adult↗
PubMed1992

"Paralogs", sorbent families for protein separations.

Novel peptide-based (paralog) sorbents are evaluated with respect to performance, reproducibility and reusability in a 96-well test plate screening format, and to utility in protein separations. The results demonstrate that this approach to constructing sorbents provides a new and generally applicable set of tools for separating proteins.

Adsorption↗
PubMed1992

Naturally occurring undercuts in the retention of an interim oculofacial prosthesis.

The use of adhesives in retaining maxillofacial prostheses has been advocated and applied for many years. Implant placement has reduced the need for adhesives in some patients but is impractical when ablative surgery is followed by radiation treatment. A technique is described that permits the rapid fabrication of an oculofacial prosthesis that uses naturally occurring orbital undercuts for retention, rather than adhesives that may further irritate radiated tissues.

Eye, Artificial↗
PubMed1992

Pilot study to compare the bronchodilator and metabolic responses to terbutaline infusion in seven asthmatic subjects--are they correlated?

We compared the changes in peak expiratory flow rate (PEFR), plasma potassium and plasma glucose during and after an infusion of the beta 2-agonist, terbutaline, in seven asthmatic subjects. Our aim was to establish whether these metabolic parameters could be correlated with PEFR. The percentage changes in PEFR were significantly correlated with the percentage changes in glucose (r = 0.60, P less than 0.001) and potassium (r = -0.64, P less than 0.001). Values for glucose and potassium changes were also correlated significantly with each other (r = 0.86, P less than 0.001). This suggests that in asthmatic subjects on beta 2-agonist treatment, plasma potassium could be used as a surrogate marker for beta 2 activity at bronchi. It also implies that the most effective beta 2-agonist bronchodilators will produce the greatest fall in plasma potassium. Further studies with a larger number of patients are needed to confirm this.

Adult↗