Prospects for macrolide therapy of asthma and COPD

Macrolide compounds, many of which are derived from natural sources, all share a lactone ring structure, but of varying sizes. Their biological activities differ with structure and size but tend to overlap. Marketed macrolide drugs include immunosuppressives and antibiotics. Some of the latter have been shown to exert anti-inflammatory activities, due to direct effects on inflammatory cells and processes when used for respiratory infections. Consequently, azithromycin is included in clinical guidelines for COPD and asthma treatment, though it has the disadvantage, as an antibiotic, of increasing bacterial resistance. COPD and asthma, however, like several chronic inflammatory diseases involving other organs, are driven to a large extent by epithelial barrier dysfunction. Recently, azithromycin was shown to directly enhance epithelial barrier function and a new class of derivatives, barriolides, is under development with the lead indication COPD. It is thus likely that by circumventing antibiosis and acting on a crucial etiological disease process, this type of agent will open up a new, safer approach to COPD and asthma therapy with macrolides.

CCL20 neutralization by a monoclonal antibody in healthy subjects selectively inhibits recruitment of CCR6+ cells in an experimental suction blister

AIMS

GSK3050002, a humanized IgG1κ antibody with high binding affinity to human CCL20, was administered in a first-in-human study to evaluate safety, pharmacokinetics (PK) and pharmacodynamics (PD). An experimental skin suction blister model was employed to assess target engagement and the ability of the compound to inhibit recruitment of inflammatory CCR6 expressing cells.

METHODS

This study was a randomized, double-blind (sponsor open), placebo-controlled, single-centre, single ascending intravenous dose escalation trial in 48 healthy male volunteers.

RESULTS

GSK3050002 (0.1-20 mg kg^-1 ) was well tolerated and no safety concerns were identified. The PK was linear over the dose range, with a half-life of approximately 2 weeks. Complex of GSK3050002/CCL20 increased in serum and blister fluid with increasing doses of GSK3050002. There were dose-dependent decreases in CCR6⁺ cell recruitment to skin blisters with maximal effects at doses of 5 mg kg^-1 and higher, doses at which GSK3050002/CCL20 complex in serum and blister fluid also appeared to reach maximum levels.

CONCLUSIONS

These results indicate a relationship between PK, target engagement and PD, suggesting a selective inhibition of recruitment of CCR6⁺ cells by GSK3050002 and support further development of GSK3050002 in autoimmune and inflammatory diseases.

Effect of Inhaled Interferon Beta-1a on Carbon Monoxide Transfer Factor in Healthy Volunteers

Interferon beta-1a (IFNβ-1a) 30 μg weekly by intramuscular (IM) injection is used to treat relapsing forms of multiple sclerosis. We assessed if it can be given safely by inhalation. Twenty-one healthy volunteers inhaled IFNβ-1a 300 μg, formulated for deep delivery to the lungs, in a randomized, parallel-group, repeat-dose trial. Comparators were room air and placebo. The primary outcome measure was carbon monoxide transfer factor corrected for hemoglobin (TLCOc), which measures the CO transfer from inspired gas to pulmonary capillary blood. After 3 and 4 once-weekly doses, IFNβ-1a significantly reduced TLCOc compared with room air: after the third dose, mean standard deviation (SD) change in percent predicted TLCOc was-10.9 (2.8), and after the fourth dose was-12.1 (2.7). After 2, 3, and 4 doses, IFNβ-1a significantly reduced TLCOc compared with placebo: after the second dose, mean (SD) change in percent predicted TLCOc was-8.8 (5.5), after the third dose was-10.9 (2.8), and after the fourth dose was-12.1 (2.7). Circulating IFNβ-1a concentrations were about one-third those of the intramuscular dose regimen. Tolerability of IFNβ-1a and the comparators was equally good. In conclusion, IFNβ-1a reduced TLCOc, whereas placebo and room air did not. A dose of IFNβ-1a 300 μg by inhalation may not be safe for general use.

The effect of GSK2190915, a 5-lipoxygenase-activating protein inhibitor, on exercise-induced bronchoconstriction

Exercise-induced bronchoconstriction (EIB) describes the condition whereby exercise causes airflow obstruction that lasts for up to 90 minutes without treatment. This double-blind, placebo-controlled, five-way crossover study investigated the dose response and duration of action of a 5-lipoxygenase-activating protein inhibitor, GSK2190915, to inhibit EIB in subjects with asthma. Forty-seven subjects with EIB were enrolled. Exercise challenge testing was scheduled at 2, 9.5, and 24 hours after receiving a single dose of GSK2190915 (10, 50, 100, and 200 mg) or placebo in randomized order. GSK2190915 at 200 and 100 mg significantly attenuated the response to exercise at 2 and 9.5 hours postdose, respectively, compared with placebo. The adjusted mean maximum percentage change from baseline forced expiratory volume at 1 second within 60 minutes postexercise challenge (FEV1 (0-60)) treatment difference for GSK2190915 at 200 mg compared with placebo at 2 hours postdose was 6.30% (95% CI, 3.06, 9.54), corresponding to a 40% attenuation of the placebo response to exercise; the treatment difference between GSK2190915 at 100 mg and placebo at 9.5 hours postdose was 3.49% (95% CI, 1.02, 5.95), corresponding to a 41% attenuation of the placebo response to exercise. No significant effect was seen at 24 hours postdose with any dose; however, investigation of statistically significant treatment-related effects at this time point was limited because of the small fall in adjusted mean FEV1 (0-60) (-7.61%; 95% CI, -10.23, -4.99) after placebo. GSK2190915 may be of benefit in EIB prevention. GSK Clinical Study LPA112025; ClinicalTrials.gov identifier number: NCT00812929.

Effects of a FLAP inhibitor, GSK2190915, in asthmatics with high sputum neutrophils

Patients with refractory asthma frequently have neutrophilic airway inflammation and respond poorly to inhaled corticosteroids. This study evaluated the effects of an oral 5-lipoxygenase-activating protein (FLAP) inhibitor, GSK2190915, in patients with asthma and elevated sputum neutrophils. Patients received 14 (range 13-16) days treatment with GSK2190915 100 mg and placebo with a minimum 14 day washout in a double-blind, cross-over, randomised design (N = 14). Sputum induction was performed twice pre-dose in each treatment period to confirm sputum neutrophilia, and twice at the end of each treatment period. The primary endpoint was the percentage and absolute sputum neutrophil count, averaged for end-of-treatment visits. GSK2190915 did not significantly reduce mean percentage sputum neutrophils (GSK2190915-placebo difference [95% CI]: -0.9 [-12.0, 10.3]), or mean sputum neutrophil counts (GSK2190915/placebo ratio [95% CI]: 1.06 [0.43, 2.61]). GSK2190915 resulted in a marked suppression (>90%) of sputum LTB4 and urine LTE4, but did not alter clinical endpoints. There were no safety issues. Despite suppressing the target mediator LTB4, FLAP inhibitor GSK2190915 had no short-term effect on sputum cell counts or clinical endpoints in patients with asthma and sputum neutrophilia.

Inhibition of the early asthmatic response to inhaled allergen by the 5-lipoxygenase activating protein inhibitor GSK2190915: a dose-response study

Background

GSK2190915, a 5-lipoxygenase activating protein inhibitor, inhibits the production of cysteinyl leukotrienes and leukotriene B4 and 5-oxo-6,8,11,14-eicosatetraenoic acid. We have previously reported that GSK2190915 100 mg daily inhibits early and late asthmatic responses to inhaled allergen; the effects of lower doses have not been reported. This study assessed the dose–response effects of GSK2190915 10 mg and 50 mg on the early asthmatic response (EAR) to inhaled allergen.

Methods

Nineteen subjects with mild asthma and an EAR were enrolled in a randomized, double-blind, three-way crossover study of GSK2190915 10 mg, 50 mg, and placebo orally once-daily for 3 days. Allergen challenge was performed 2 hours after the third dose.

Results

Compared with placebo, GSK2190915 10 mg and 50 mg caused significant, dose-dependent attenuation of the minimum forced expiratory volume at 1 second (FEV₁) absolute change from baseline; mean treatment differences were 0.21 L (95% confidence interval [CI] 0.04 L, 0.38 L) and 0.41 L (95% CI 0.24 L, 0.58 L), respectively. GSK2190915 50 mg was more effective than 10 mg; mean difference between treatments was 0.20 L, (95% CI 0.03 L, 0.36 L). Compared with placebo, GSK2190915 50 mg, but not 10 mg, significantly inhibited the weighted mean FEV₁ absolute change from baseline.

Conclusion

GSK2190915 50 mg attenuated the EAR similarly to GSK2190915 100 mg in our previous study, suggesting 50 mg is at the top of the dose–response curve. GSK2190915 10 mg is a suboptimal dose. The EAR can be used to assess the therapeutic dose of a new treatment for asthma.

Pharmacodynamics, pharmacokinetics and safety of GSK2190915, a novel oral anti-inflammatory 5-lipoxygenase-activating protein inhibitor

AIM

To assess the pharmacokinetics, pharmacodynamics, safety and tolerability of the 5-lipoxygenase-activating protein inhibitor, GSK2190915, after oral dosing in two independent phase I studies, one in Western European and one in Japanese subjects, utilizing different formulations.

METHOD

Western European subjects received single (50-1000 mg) or multiple (10-450 mg) oral doses of GSK2190915 or placebo in a dose-escalating manner. Japanese subjects received three of four GSK2190915 doses (10-200 mg) plus placebo once in a four period crossover design. Blood samples were collected for GSK2190915 concentrations and blood and urine were collected to measure leukotriene B₄ and leukotriene E₄, respectively, as pharmacodynamic markers of drug activity.

RESULTS

There was no clear difference in adverse events between placebo and active drug-treated subjects in either study. Maximum plasma concentrations of GSK2190915 and area under the curve increased in a dose-related manner and mean half-life values ranged from 16-34 h. Dose-dependent inhibition of blood leukotriene B₄ production was observed and near complete inhibition of urinary leukotriene E₄ excretion was shown at all doses except the lowest dose. The EC₅₀ values for inhibition of LTB₄ were 85 nM and 89 nM in the Western European and Japanese studies, respectively.

CONCLUSION

GSK2190915 is well-tolerated with pharmacokinetics and pharmacodynamics in Western European and Japanese subjects that support once daily dosing for 24 h inhibition of leukotrienes. Doses of ≥50 mg show near complete inhibition of urinary leukotriene E₄ at 24 h post-dose, whereas doses of ≥150 mg are required for 24 h inhibition of blood LTB₄.

The 5-lipoxygenase-activating protein inhibitor, GSK2190915, attenuates the early and late responses to inhaled allergen in mild asthma

BACKGROUND

GSK2190915, a potent 5-lipoxygenase-activating protein inhibitor, prevents the synthesis of leukotrienes and 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE).

OBJECTIVE

To assess the effect of GSK2190915 on the allergen-induced asthmatic responses.

METHODS

Nineteen eligible male subjects with mild asthma were enrolled in and completed this four-centre, double-blind, two-way crossover study (ClinicalTrials.gov NCT00748306). Subjects took GSK2190915 100 mg and placebo orally once daily for 5 days in randomized order. On Day 1 and 4 they had a methacholine challenge, on Day 3 they had an inhaled allergen challenge, and on Days 4 and 6 they had sputum induction.

RESULTS

GSK2190915 attenuated the early (0-2 h) and late (4-10 h) asthmatic responses to inhaled allergen compared with placebo. There was a statistically significant attenuation of the early asthmatic response (EAR) by GSK2190915; treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) EAR was 0.408 L (0.205, 0.611). There was a statistically significant attenuation of the late asthmatic response (LAR) by GSK2190915; the treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) LAR was 0.229 L (0.041, 0.417). There was a statistically significant attenuation of allergen-induced sputum eosinophil count on Day 4 following GSK2190915: mean treatment difference (95% CI) between GSK2190915 and placebo was -9.95% (-18.15%, -1.77%). Compared with placebo, GSK2190915 100 mg reduced median sputum LTB(4) by > 90% on Days 4 and 6. There was no effect on methacholine PC(20) post allergen. GSK2190915 was generally well tolerated.

CONCLUSION AND CLINICAL RELEVANCE

GSK2190915 shows potential as a treatment for patients with asthma.

Vilanterol trifenatate, a novel inhaled long-acting beta2 adrenoceptor agonist, is well tolerated in healthy subjects and demonstrates prolonged bronchodilation in subjects with asthma and COPD

Vilanterol (VI; GW642444M) is a novel inhaled long-acting β2-agonist with inherent 24 h activity in vitro in development as a combination with the inhaled corticosteroid fluticasone furoate for both COPD and asthma. These studies were conducted to determine the safety, tolerability, pharmacodynamics and pharmacokinetics of VI in healthy subjects and subjects with mild to moderate persistent asthma and moderate to severe COPD. Single doses of VI (25-100 μg) were given once daily to subjects with asthma and COPD and repeat doses once daily for 14 days to healthy subjects. Adverse events (AEs), vital signs, ECGs, pharmacodynamic endpoints, FEV(1) and VI plasma pharmacokinetics (AUC, Cmax and Tmax) were determined following dosing. VI (25-100 μg) was well tolerated. The incidence and severity of AEs were comparable to placebo. Following VI administration there were no clinically significant abnormalities in vital signs, 12-lead ECG, Holter ECG, blood glucose or potassium. There were no statistically significant effects on QTc of single and repeat VI doses up to 50 μg; some differences were seen following the 100 μg VI dose after single and repeat dose in healthy subjects and single dose in asthmatic subjects. All VI doses produced increases in FEV(1) from as early as 5 min after dosing which were maintained up to 24 h post-dose in subjects with asthma and COPD. In all subjects VI was rapidly absorbed (healthy subjects median Tmax at 5 min; asthma and COPD subjects median Tmax at 10 min) with systemic exposure increasing in an approximately dose proportional manner across the VI dose range. Marginal accumulation was seen on repeat dosing. Single doses of inhaled VI in subjects with asthma and COPD and repeat doses in healthy subjects were well tolerated with no clinically significant unwanted systemic effects. VI produced a rapid and prolonged bronchodilation over 24 h suggesting the potential for once daily administration.

Phenotypic variability of patients homozygous for the GJB2 mutation 35delG cannot be explained by the influence of one major modifier gene

Hereditary hearing loss (HL) is a very heterogeneous trait, with 46 gene identifications for non-syndromic HL. Mutations in GJB2 cause up to half of all cases of severe-to-profound congenital autosomal recessive non-syndromic HL, with 35delG being the most frequent mutation in Caucasians. Although a genotype-phenotype correlation has been established for most GJB2 genotypes, the HL of 35delG homozygous patients is mild to profound. We hypothesise that this phenotypic variability is at least partly caused by the influence of modifier genes. By performing a whole-genome association (WGA) study on 35delG homozygotes, we sought to identify modifier genes. The association study was performed by comparing the genotypes of mild/moderate cases and profound cases. The first analysis included a pooling-based WGA study of a first set of 255 samples by using both the Illumina 550K and Affymetrix 500K chips. This analysis resulted in a ranking of all analysed single-nucleotide polymorphisms (SNPs) according to their P-values. The top 250 most significantly associated SNPs were genotyped individually in the same sample set. All 192 SNPs that still had significant P-values were genotyped in a second independent set of 297 samples for replication. The significant P-values were replicated in nine SNPs, with combined P-values between 3 x 10(-3) and 1 x 10(-4). This study suggests that the phenotypic variability in 35delG homozygous patients cannot be explained by the effect of one major modifier gene. Significantly associated SNPs may reflect a small modifying effect on the phenotype. Increasing the power of the study will be of greatest importance to confirm these results.

Method for macromolecular colocalization using atomic recombination in dynamic SIMS

Localizing two or more components of assemblies in biological systems requires both continued development of fluorescence techniques and invention of entirely new techniques. Candidates for the latter include dynamic secondary ion mass spectrometry (D-SIMS). The latest generation of D-SIMS, the Cameca NanoSIMS 50, permits the localization of specific, isotopically labeled molecules and macromolecules in sections of biological material with a resolution in the tens of nanometers and with a sensitivity approaching in principle that of a single protein. Here we use two different systems, crystals of glycine and mixtures of proteins, to show that the formation of recombinant CN secondary ions under Cs bombardment can be exploited to create a new colocalization technique. We show experimentally that the formation of the recombinant (13)C(15)N secondary ion between (13)C- and (15)N-labeled macromolecules is indeed an indicator of the distance between the interacting macromolecules and on their shape. We build up a convolution model of the mixing-recombination process in D-SIMS that allows quantitative interpretations of the distance-dependent formation of the recombinant CN. Our results show that macromolecules can be colocalized if they are within 2 nm of one another. We discuss the potential advantages of this new technique for biological applications.

Combined analysis of three crossover clinical pharmacology studies of effects of rabeprazole and esomeprazole on 24-h intragastric pH in healthy volunteers

AIM

To compare antisecretory effects of rabeprazole and esomeprazole after single and repeat dosing in Helicobacter pylori-negative healthy volunteers.

METHODS

Results were pooled from three smaller, open, crossover, randomized studies to obtain data from 80 subjects. The studies compared: (a) 5 days' dosing of 20 mg rabeprazole and esomeprazole (n = 24); (b) single doses of rabeprazole 20 mg and esomeprazole 40 mg (n = 27) and (c) 5 days' dosing of rabeprazole 10 mg and esomeprazole 20 mg (n = 29). Washout periods were > or =14 days. Intragastric pH was recorded continuously for 24 h on days 0, 1 and 5.

RESULTS

Single doses of rabeprazole 20 mg maintained 24-h intragastric pH >4 for longer than esomeprazole 20 mg (45% vs. 32%; P < 0.001); rabeprazole 20 mg and esomeprazole 40 mg were equivalent in their effects. After 5 days' dosing, rabeprazole 20 mg maintained pH >4 for longer than esomeprazole 20 mg (62% vs. 56%; P = 0.046); the reverse was true for esomeprazole 20 mg vs. rabeprazole 10 mg (56% vs. 48%; P = 0.035). In general, intragastric pH AUC during 0-5 h after dosing was higher after esomeprazole than rabeprazole, whereas the reverse was true during the night.

CONCLUSIONS

The order of effects on 24-h pH was: rabeprazole 10 mg < or = esomeprazole 20 mg < rabeprazole 20 mg = esomeprazole 40 mg. Esomeprazole acts faster, whereas rabeprazole's effect lasts longer.

Lipid domain boundaries as prebiotic catalysts of peptide bond formation

To address central problems in the origin of life such as the formation of linear polymers composed of only a small number of types of molecules, we have modeled the distribution of peptides in lipid monolayers. We show that short peptides and amino acids accumulate at the boundary between lipid domains, and that the concentration towards the boundary is higher the longer the peptide. We invoke a constraint on diffusion to one dimension as well as on orientation to suggest that polymerization of peptides is more likely to occur at the domain boundary than within domains or in the bulk phase. In a simple model, in which polymerization is taken to occur only at the boundary, we show that the equilibrium distribution of polymer lengths is shifted towards longer peptides. Since the reaction is occurring in a partially non-aqueous environment, hydrolysis is reduced and condensation increased to yield a significant polymerization. We show also that the free energy change from the redistribution of peptides within domains is sufficient to drive the formation of the peptide bond.

Memory processes in the response of plants to environmental signals

Plants are sensitive to stimuli from the environment (e.g., wind, rain, contact, pricking, wounding). They usually respond to such stimuli by metabolic or morphogenetic changes. Sometimes the information corresponding to a stimulus may be "stored" in the plant where it remains inactive until a second stimulus "recalls" this information and finally allows it to take effect. Two experimental systems have proved especially useful in unravelling the main features of these memory-like processes.In the system based on Bidens seedlings, an asymmetrical treatment (e.g., pricking, or gently rubbing one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. This information may be stored within the seedlings, without taking effect, for at least two weeks; then the information may be recalled by subjecting the seedlings to a second, appropriate, treatment that permits transduction of the signal into the final response (differential growth of the buds). Whilst storage is an irreversible, all-or-nothing process, recall is sensitive to a number of factors, including the intensity of these factors, and can readily be enabled or disabled. In consequence, it is possible to recall the stored message several times successively.In the system based on flax seedlings, stimulation such as manipulation stimulus, drought, wind, cold shock and radiation from a GSM telephone or from a 105 GHz Gunn oscillator, has no apparent effect. If, however, the seedlings are subjected at the same time to transient calcium depletion, numerous epidermal meristems form in their hypocotyls. When the calcium depletion treatment is applied a few days after the mechanical treatment, the time taken for the meristems to appear is increased by a number of days exactly equal to that between the application of the mechanical treatment and the beginning of the calcium depletion treatment. This means that a meristem-production information corresponding to the stimulation treatment has been stored in the plants, without any apparent effect, until the calcium depletion treatment recalls this information to allow it to take effect. Gel electrophoresis has shown that a few protein spots are changed (pI shift, appearance or disappearance of a spot) as a consequence of the application of the treatments that store or recall a meristem-production signal in flax seedlings. A SIMS investigation has revealed that the pI shift of one of these spots is probably due to protein phosphorylation. Modifications of the proteome have also been observed in Arabidopsis seedlings subjected to stimuli such as cold shock or radiation from a GSM telephone.

Poly-(R)-3-hydroxybutyrate and the pioneering work of Rosetta Natoli Reusch

In investigating genetic competence, Reusch and collaborators have found that the concentration of short chain poly-(R)-3-hydroxybutyrate (PHB) and polyphosphate (polyP) complexes increases with genetic transformability and that interrupting DNA uptake yields single-stranded donor DNA complexed with short chain PHB. This would be consistent with the organic polyphosphate, DNA, replacing the inorganic polyphosphate, polyP, in the PHB pore so allowing the DNA to be drawn into the cell. Reusch has gone on to show that PHB and polyphosphate, extracted from membranes or synthesized chemically, together form a voltage-activated calcium-selective channel. One may wonder whether the classical proteinaceous calcium channels have a short chain PHB/polyP core--and whether other ion channels have this core too. It is therefore significant that in Streptomyces lividans the potassium channel KcsA, which resembles that of eukaryotes, forms tetramers that contain polyP whilst both monomers and tetramers are covalently linked to short chain PHB. Pumps are the counterparts of channels. Reusch has also shown that a model pump, the calcium ATPase pump of human erythrocytes, contains both cPHB and polyP and has strongly implicated these polymers in its functioning. Again, one may wonder whether these polymers are essential constituents of other pumps. Reusch has gone on to show that a wide range of proteins are modified post-translationally by covalent addition of short chain PHB in both prokaryotes and eukaryotes including DNA-binding proteins such as histones. Finally, Reusch has extended the importance of short chain PHB to medicine by showing its likely involvement in atherogenic plaques and diabetes. And yet this opus has gone largely unnoticed.

Effect of IVL745, a VLA-4 antagonist, on allergen-induced bronchoconstriction in patients with asthma

BACKGROUND

Very late antigen (VLA-4) antagonists have been proposed as potential therapies for diseases in which cell recruitment and accumulation are causative. Asthma, which is characterized by airway inflammation involving the accumulation of eosinophils and mononuclear cells, is one such disease.

OBJECTIVE

We sought to assess the effect of IVL745, a VLA-4 antagonist, on the early and late asthmatic response (LAR) and on markers of airway inflammation after allergen inhalation.

METHODS

The study was of a placebo-controlled, double-blind, randomized, 2-way crossover design. Sixteen subjects with mild-to-moderate asthma controlled with short-acting beta2-agonists only and with a LAR to inhaled allergen participated in the study. At one treatment period they took 20 mg of IVL745 and one treatment period placebo. Both treatments were taken twice daily for 7 days, with a single dose on day 8. Treatments were separated by a washout period of at least 2 weeks. On day 7 of each treatment period, sputum was induced and collected, and exhaled nitric oxide (NO) was measured. On day 8, an inhaled bolus allergen challenge was performed, and blood was taken for pharmacokinetics. On day 9, exhaled NO was measured, and a methacholine challenge was done. On day 10, sputum was induced and collected. Adverse events, peak expiratory flow (PEF), use of short-acting beta2-agonists, and asthma symptoms were recorded daily throughout the study.

RESULTS

There was no statistically significant difference between IVL745 and placebo in the effect on the LAR after allergen challenge, as measured by the area under the curve of the percentage change in FEV1 from the prechallenge baseline (mean [SEM], -81.99 [18.80] after IVL745 and -72.58 [21.29] after placebo; 95% CI of difference, -36 to 16.8; P = .46) or by the maximum percentage change from the prechallenge baseline (mean [SEM], -23.44 [4.73] after IVL745 and -21.30 [5.17] after placebo; 95% CI of difference, -11 to 6.29; P = .60). There was a statistically significant decrease in the percentage of eosinophils in sputum on day 7 of treatment with IVL745 (mean [SEM], 7.32 [1.46]) compared with placebo (mean [SEM], 15.00 [1.92]; 95% CI of difference, -13 to -1.2; P = .02). There was no statistically significant difference between IVL745 and placebo with respect to the early asthmatic response, methacholine hyperresponsiveness, exhaled NO, postallergen sputum, symptoms, inhaled beta2-agonist use, or PEF.

CONCLUSION

In patients with mild-to-moderate atopic asthma, IVL745 did not affect the early and late response to inhaled allergen or markers of airway inflammation, except for a modest reduction in sputum eosinophils.

A logical (discrete) formulation for the storage and recall of environmental signals in plants

When subjected to an appropriate asymmetric stimulus, seedlings of Bidens pilosa L. "store" a symmetry-breaking instruction that will finally take effect (in the form of a differential growth of the cotyledonary buds) only if the plants are in a state in which they can "recall" this information. The ability of the plants to recall the stored symmetry-breaking instruction may be switched "on" or "off" by the application of a variety of stimuli. Although its detailed phenomenology is rather complicated, the overall behaviour of the plant storage/recall system can be modelled by use of an asynchronous, logical (discrete) description involving positive and negative feedback circuits, which are required for the existence of multi-stationarity and stability, respectively. The state tables, as used in this formalism, give a concise and easy-to-handle description of the evolution of the system and make it particularly easy to determine its stable states. This modelling approach may be extended to the formulation of many other experimental systems.

The complete phosphotransferase system in Escherichia coli

We here tabulate and describe all currently recognized proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) and their homologues encoded within the genomes of sequenced E. coli strains. There are five recognized Enzyme I homologues and six recognized HPr homologues. A nitrogen-metabolic PTS phosphoryl transfer chain encoded within the rpoN and ptsP operons and a tri-domain regulatory PTS protein encoded within the dha (dihydroxyacetone catabolic) operon, probably serve regulatory roles exclusively. In addition to several additional putative regulatory proteins, there are 21 (and possibly 22) recognized Enzyme II complexes. Of the 21 Enzyme II complexes, 7 belong to the fructose (Fru) family, 7 belong to the glucose (Glc) family, and 7 belong to the other PTS permease families. All of these proteins are briefly described, and phylogenetic data for the major families are presented.

Chromosome separation and segregation in dinoflagellates and bacteria may depend on liquid crystalline states

The patterns characteristic of certain liquid crystals called 'twisted nematics' or 'cholesterics' have been observed in thin sections of both dinoflagellates and bacterial chromosomes. These liquid crystals have also been obtained in vitro in concentrated DNA solutions. A large part of DNA in prokaryotic chromosomes forms such a twisted liquid crystal, whilst the remainder consists of lateral loops and is less concentrated. These semi-ordered phases could help chromosome separation to occur during and after DNA replication. We suggest that, owing to chemical differences, one of the two replicated filaments is immiscible with the rest of DNA in this chromosome. This immiscibility occurs in the context of an ordered liquid, with the DNA closely layered by a regular twist, a situation proposed to strongly minimize entangling after replication and hence to facilitate segregation.

Hypothesis: membrane domains and hyperstructures control bacterial division

The mechanism responsible for creating the division site in the right place at the right time in bacteria is unknown. It has been attributed to the formation of proteolipid domains in the cytoplasmic membrane surrounding the nucleoids. We interpret the growing evidence for this hypothesis by invoking hyperstructures, which exist at a level of organization intermediate between macromolecules and genes. Non-equilibrium hyperstructures comprise the genes, mRNA proteins and lipids required for a particular function such as cell division, and assemble and disassemble according to the needs of the cell.

A SeqA hyperstructure and its interactions direct the replication and sequestration of DNA

A level of explanation in biology intermediate between macromolecules and cells has recently been proposed. This level is that of hyperstructures. One class of hyperstructures comprises the genes, mRNA, proteins and lipids that assemble to fulfil a particular function and disassemble when no longer required. To reason in terms of hyperstructures, it is essential to understand the factors responsible for their formation. These include the local concentration of sites on DNA and their cognate DNA-binding proteins. In Escherichia coli, the formation of a SeqA hyperstructure via the phenomenon of local concentration may explain how the binding of SeqA to hemimethylated GATC sequences leads to the sequestration of newly replicated origins of replication.

Submolecular Structures in Dipalmytoylphosphatidylethanolamine Langmuir-Blodgett Films Observed by Scanning Force Microscopy

Dipalmitoylphosphatidylethanolamine (DDPE) Langmuir films at the air/water interface have been studied. These films exhibit high stability. The resulting films transferred on muscovite have been studied by scanning force microscopy with the contact mode. At the microscopic scale, DDPE Langmuir-Blodgett films appear densely packed with few defects. At molecular resolution the films appear well ordered; the double tail of the lipids has been observed.d Copyright 2000 Academic Press.

Effects of calcium and calcium chelators on growth and morphology of Escherichia coli L-form NC-7

Growth of a wall-less, L-form of Escherichia coli specifically requires calcium, and in its absence, cells ceased dividing, became spherical, swelled, developed large vacuoles, and eventually lysed. The key cell division protein, FtsZ, was present in the L-form at a concentration five times less than that in the parental strain. One interpretation of these results is that the L-form possesses an enzoskeleton partly regulated by calcium.

Long-distance transport, storage and recall of morphogenetic information in plants. The existence of a sort of primitive plant 'memory'

An asymmetrical treatment of Bidens seedlings (pricking one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. The symmetry-breaking signal propagates within the seedlings at a rate of at least a fraction of a millimetre per second. This information may be 'stored' (STO function) within the seedlings, without taking effect, for at least 2 weeks; then the information may be 'recalled' (RCL function), thus permitting transduction of the signal into the final response (differential growth of the buds), as a consequence of subjecting the seedlings to various symmetrical or asymmetrical treatments. A similar behaviour was observed with stimuli other than pricking (including non-traumatic stimuli), with plants other than Bidens (flax, tomato), and with responses other than cotyledonary-bud growth (hypocotyl elongation, induction of meristems, thigmomorphogenesis). There are indications that storage may involve the activation of elements implicated in cell cycle control, and that the last steps of the final response involve genes such as tch1 and hsp70. The adaptive advantage for plants in possessing STO/RCL functions is discussed. Manipulating the STO/RCL functions may have interesting practical applications, e.g. in the resistance of plants to natural stresses. The existence of the STO/RCL functions in plants constitutes an elementary form of 'memory' which may provide an experimental system simpler than the animal brain to test the validity of the theoretical models of interpretation of important features such as memory storage and evocation.

Effects of glucocorticoids and mineralocorticoids on proliferation and maturation of human peripheral blood stem cells

It has been shown that hematopoietic progenitors can be expanded ex vivo in the presence of various cytokine combinations. Glucocorticoids (GC) are involved in the self-renewal of erythroid progenitors in chicken. To see whether GC have a similar effect on hematopoiesis in humans, CD34(+) peripheral blood stem cells were cultured in serum free medium in the presence of a GC, triamcinolone acetonide. However, our results demonstrate an inhibition of both erythroid and granulocyte-macrophage (GM) proliferation and a modification of erythroid colony morphology. Furthermore, RU38486 (Mifepristone), a potent GC antagonist, was unable to reverse the inhibitory effect of triamcinolone acetonide. We also identified and characterized another steroid subfamily, the mineralocorticoid (MC) subfamily, in human PB CD34(+) cells. The MC, aldosterone, significantly enhanced GM colony formation and diminished the erythroid colony number. Neither of effects were inhibited by ZK91587, an antagonist specific to the MC receptor (MCR). In contrast, ZK91587 reversed the stimulatory effect of deoxycorticosterone on GM colony formation. Cytoplasmic staining for MCR was observed in CD34(+) cells incubated with a polyclonal antiserum raised against human MCR. To our knowledge, this is the first demonstration of the presence of MCR in human PB CD34(+) cells.

Effects of glucocorticoids and mineralocorticoids on proliferation and maturation of human peripheral blood stem cells

It has been shown that hematopoietic progenitors can be expanded ex vivo in the presence of various cytokine combinations. Glucocorticoids (GC) are involved in the self-renewal of erythroid progenitors in chicken. To see whether GC have a similar effect on hematopoiesis in humans, CD34(+) peripheral blood stem cells were cultured in serum free medium in the presence of a GC, triamcinolone acetonide. However, our results demonstrate an inhibition of both erythroid and granulocyte-macrophage (GM) proliferation and a modification of erythroid colony morphology. Furthermore, RU38486 (Mifepristone), a potent GC antagonist, was unable to reverse the inhibitory effect of triamcinolone acetonide. We also identified and characterized another steroid subfamily, the mineralocorticoid (MC) subfamily, in human PB CD34(+) cells. The MC, aldosterone, significantly enhanced GM colony formation and diminished the erythroid colony number. Neither of effects were inhibited by ZK91587, an antagonist specific to the MC receptor (MCR). In contrast, ZK91587 reversed the stimulatory effect of deoxycorticosterone on GM colony formation. Cytoplasmic staining for MCR was observed in CD34(+) cells incubated with a polyclonal antiserum raised against human MCR. To our knowledge, this is the first demonstration of the presence of MCR in human PB CD34(+) cells.

Hypothesis: hyperstructures regulate bacterial structure and the cell cycle

A myriad different constituents or elements (genes, proteins, lipids, ions, small molecules etc.) participate in numerous physico-chemical processes to create bacteria that can adapt to their environments to survive, grow and, via the cell cycle, reproduce. We explore the possibility that it is too difficult to explain cell cycle progression in terms of these elements and that an intermediate level of explanation is needed. This level is that of hyperstructures. A hyperstructure is large, has usually one particular function, and contains many elements. Non-equilibrium, or even dissipative, hyperstructures that, for example, assemble to transport and metabolize nutrients may comprise membrane domains of transporters plus cytoplasmic metabolons plus the genes that encode the hyperstructure's enzymes. The processes involved in the putative formation of hyperstructures include: metabolite-induced changes to protein affinities that result in metabolon formation, lipid-organizing forces that result in lateral and transverse asymmetries, post-translational modifications, equilibration of water structures that may alter distributions of other molecules, transertion, ion currents, emission of electromagnetic radiation and long range mechanical vibrations. Equilibrium hyperstructures may also exist such as topological arrays of DNA in the form of cholesteric liquid crystals. We present here the beginning of a picture of the bacterial cell in which hyperstructures form to maximize efficiency and in which the properties of hyperstructures drive the cell cycle.

The mechanical advantages of DNA

The elastic properties of DNA and the contractile activities of enzymes involved in transcription, translation and supercoiling may have contributed to the ability of early cells (protocells) to withstand turgor pressure. In the hypothesis proposed here, resistance to turgor resulted from (1) the elastic properties of DNA which was connected to the membrane by association with positively charged lipids and with membrane peptides, (2) the coupled transcription-translation-insertion of peptides into membrane--transertion--which connected membranes with phase-condensed DNA, and (3) the action of topoisomerases which supercoiled and shortened DNA. The existence of a negative feedback system is also proposed to explain how weakened regions of membrane were preferentially strengthened. It may prove possible to test this hypothesis by studying transertion using optical tweezers and by studying wall-less L-form bacteria.

Protein phosphorylation in Escherichia coli L. form NC-7

Wall-less L-forms of Escherichia coli constitute an interesting, and relatively underused, model system for numerous studies of bacterial physiology including the cell cycle, intracellular structure and protein phosphorylation. Total extracts of the L-form revealed a pattern of protein phosphorylation similar to that of an enteropathogenic strain but very different from its parental K-12 strain. In particular, the L-form extract revealed phosphorylation on tyrosine of a protein important in pathogenesis, TypA, and calcium-specific phosphorylation of a 40 kDa protein. Two new phosphoproteins were identified in the L-form as the DNA-binding protein Dps, and YfiD, a protein of 14 kDa with homology to pyruvate formate-lyase and a region containing a tRNA cluster in bacteriophage T5.

A fission-fusion origin for life

To develop a comprehensive 'cells-first' approach to the origin of life, we propose that protocells form spontaneously and that the fission and fusion of these protocells drives the dynamics of their evolution. The fitness criterion for this evolution is taken to be the the stability (conservation) of domains in the protocellular membrane as determined by non-covalent molecular associations between the amphiphiles of the membrane and a subset of the macromolecules in the protocell. In the presence of a source of free energy the macromolecular content of the protocell (co-)evolves as the result of (domain-dependent) membrane-catalysed polymerisation of the prebiotic constituents delivered to the protocell by fusion. The metabolism of the cell therefore (co-)evolves on a rugged fitness landscape. We indicate how domain evolution with the same fitness criterion can potentially give rise to coding. Membrane domains may therefore provide the link between protocells and the RNA/DNA-world.

Modelling Escherichia coli. The concept of competitive coherence

Many of the characteristics of life are plainly evident. Others are not. In principle, computer models might be devised to test whether a hypothetical characteristic is likely to be a characteristic of real life. Here, I propose that the bacterium Escherichia coli can be considered as passing through a series of states in which a distinct set of its constituent molecules or 'elements' are active. The activity of these elements is determined by a competition between two processes. One of these processes depends on the previous cell state whilst the other depends on the internal coherence of the developing state. The simultaneous operation of these two processes I term 'competitive coherence'. To clarify and eventually test these related hypotheses, a possible computer model is outlined.

Tyrosine phosphorylation in Escherichia coli

The phosphorylation on tyrosine of a protein in Escherichia coli both in vivo and in vitro was revealed by recognition by anti-phosphotyrosine antibodies, labelling with [gamma-32P]ATP, and phosphoamino acid analysis. This protein, which we name TypA, is the product of the o591 reading frame as revealed by N-terminal sequencing and antibody cross-reactivity. Inactivation of typA altered the patterns of protein synthesis during both exponential growth and carbon starvation. These alterations included the disappearance of an acidic isoform of both the universal stress protein UspA and carbon starvation protein Csp15, and increased synthesis of the histone-like protein H-NS. The sequence of TypA from strain K-12 differs from that of an enteropathogenic strain in six amino acid residues and the protein is three residues shorter. We propose that TypA interacts with global regulatory networks and that its phosphorylation may be relevant to pathogenesis.

Rapid growth mutants of Escherichia coli

If rapid growth (rap) mutants of Escherichia coli could be obtained, these might prove a valuable contribution to fields as diverse as growth rate control, biotechnology and the regulation of the bacterial cell cycle. To obtain rap mutants, a dnaQ mutator strain was grown for four and a half days continuously in batch culture. At the end of the selection period, there was no significant change in growth rate. The result means that selecting rap mutants may require an alternative strategy and a number of such alternatives are discussed.

The universal stress protein, UspA, of Escherichia coli is phosphorylated in response to stasis

Transcriptional induction of the uspA gene of Escherichia coli occurs whenever conditions cause growth arrest and cells deficient in UspA survive poorly in stationary phase. We demonstrate that the product of uspA is a serine and threonine phosphoprotein. In vivo, three isoforms of UspA were detected, two of which were phosphorylated as determined by alkaline phosphatase treatment; in vitro, phosphorylation with [gamma-32P]ATP yielded two radioactive UspA isoforms. The phosphorylated isoforms were barely visible in growing cells but one increased during starvation conditions causing growth arrest. This phosphorylation is dependent on the o591 gene, which encodes an autophosphorylating tyrosine phosphoprotein and which is involved in the synthesis or modification of six other proteins. In vitro, UspA undergoes a rapid and dynamic autophosphorylation, as shown by chase experiments with GTP or ATP as phosphate donors.

Artefactual cleavage of E coli H-NS by OmpT

In the bacterium Escherichia coli, H-NS-(H1, H1a) is a heat-stable protein with a molecular mass of 15.5 kDa involved in nucleoid organisation and gene regulation linked to certain signal transduction pathways. We have shown that, following addition of preparations of everted inner membrane vesicles, heat-stable cleavage products of approximately 10 kDa of H-NS are formed in vitro from newly synthesised, radio-labelled H-NS and from purified H-NS. The 15.5 kDa protein and its cleavage products were also recovered from a minicell system. These results raised the possibility that cleavage of H-NS is physiologically significant. However, the cleavage of H-NS observed appears to occur during cell breakage and to depend on the method of protein extraction and the presence of the outer membrane protease, OmpT. Nevertheless, the results indicate that H-NS may contain at least two separate domains with cleavage occurring between these domains at a preferred OmpT site. Failure to take account of H-NS cleavage in sample preparation and analysis can lead to serious underestimation of H-NS levels.

Hypothesis: the meeting place model for prion disease

Prions are responsible for spongiform diseases such as scrapie and bovine spongiform encephalopathy. It is now generally accepted that the disease mechanism involves the conversion from the normal form, PrPC, to the pathogenic form, PrPSc, and that this isoform is infectious. In the case of scrapie, 15 different forms of the disease have been described and some of these different phenotypes can be conferred by infectious prions that are themselves encoded by normal genes. We propose here that a prion with an altered structure has a correspondingly altered preference for lipids; this altered preference creates a proteolipid domain containing different lipids and other factors such as chaperonins and enzymes responsible for post-translational modifications. Normal prions associated with this abnormal domain adopt the conformation dictated by its lipidic composition (and by the other factors present) and so acquire the lipidic preference of the original pathogenic prions. These transformed prions could then create new proteolipid domains. This process may be considered as semi-conservative replication in which prion and lipids are analogous to the Watson and Crick strands and the proteolipid domain to the double helix itself.

Antiviruses as therapeutic agents: a mathematical analysis of their potential

Antiviruses are designed to inhibit virus replication and arrest infections. A particular antivirus derives from a specific virus, on which it depends for propagation. Antiviruses have a natural equivalent in defective interfering particles (DIPs). To obtain design criteria for antiviruses, antivirus therapies for treating virus infections are modelled by a system of equations with continuous dynamics. The results reveal that such therapies can eliminate viruses given either a large but achievable inoculum of antivirus or an outcompeting advantage to the antivirus. Since such therapies are relatively insensitive to many parameters of infections, they may be applicable to many viral diseases.

Elements of a unifying theory of biology

To discover a unifying theory of biology, it is necessary first to believe in its existence and second to seek its elements. Such a theory would explain the regulation of the cell cycle, differentiation and the origin of life. Some elements of the theory may be obtained by considering both eukaryotic and prokaryotic cell cycles. These elements include cytoskeletal proteins, calcium, cyclins, protein kinase C, phosphorylation, transcriptional sensing, autocatalytic gene expression and the physical properties of lipids. Other more exotic candidate elements include the dynamic enzoskeleton, ATP generation, mechanotransduction, the piezoelectric effect and resonance. Bringing these disparate elements together--and discovering others--will require extensive collaborations between specialists from different sciences. This can only be achieved within the context of an integrated approach to biology.