Effect of obesity on constant workrate exercise in hyperinflated men with COPD.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) and a high body mass index (BMI) can both affect pulmonary volumes as well as exercise tolerance, but their combined effect on these outcomes is not well known. The aim of this study was to investigate the effects of increased BMI during constant workrate cycle ergometry in patients with COPD. METHODS: Men with COPD and hyperinflation were divided according to World Health Organization BMI classification: 84 normal BMI (NBMI), 130 overweight (OW) and 64 obese (OB). Patients underwent spirometric and lung volumes assessment and an incremental cycling exercise test. This was followed by a constant workrate exercise test (CET) at 75% of peak capacity. Inspiratory capacity and Borg dyspnea scores were measured at baseline, during and at the end of CET. RESULTS AND DISCUSSION: FEV1 % predicted was not different across BMI classes. Total lung capacity and functional residual capacity were significantly lower in OB and OW compared to NBMI patients. Peak VO2 in L x min(-1) was significantly higher in OB and OW patients than in NBMI patients. CET time was not different across BMI classes (p = 0.11). Changes in lung volumes and dyspnea during CET were not different between BMI categories. CONCLUSIONS: OB and OW patients with COPD had a higher peak VO2 than their lean counterparts. Endurance time, dyspnea and changes in lung volumes during CET were similar between BMI categories.

Prolonged bronchoprotection against inhaled methacholine by inhaled BI 1744, a long-acting beta(2)-agonist, in patients with mild asthma.

BACKGROUND: Long-acting ss(2)-agonists are an established controller medication in asthma. BI 1744 is a novel L\long-acting ss(2)-agonist with a preclinical profile that suggests 24-hour bronchodilation and bronchoprotection may be achieved. OBJECTIVE: To examine the bronchoprotective effects of single doses of BI 1744 against methacholine provocation in subjects with mild asthma. METHODS: Thirty-one subjects with mild asthma were randomized to receive single doses of BI 1744 (2, 5, 10, 20 microg) or placebo on separate days according to a double-blind, 5-way crossover design. Methacholine challenges were performed at 30 minutes and at 4, 8, 24, and 32 hours after each single dose of medication, and the results were expressed as PC(20) FEV(1). RESULTS: All doses of BI 1744 produced statistically significant increases in the methacholine PC(20) compared with placebo as long as 32 hours. The mean (geometric SEM) methacholine PC(20) 24 hours after dosing with placebo was 1.73 (1.13) mg/mL, which increased after 2 microg to 3.86 (1.14) mg/mL, after 5 microg to 5.67 (1.14) mg/mL, after 10 microg to 9.42 (1.13) mg/mL, and after 20 microg to 13.71 (1.14) mg/mL (all P < .0001). After 32 hours, the methacholine PC(20) value remained significantly increased for all doses. No safety or tolerability concerns were identified. CONCLUSION: BI 1744 provides significant bronchoprotection against inhaled methacholine for up to 32 hours after single-dose administration.

Performance during constant workrate cycling exercise in women with COPD and hyperinflation.

We aimed to characterize gender differences in exercise endurance, operating lung volumes and symptoms limitation during exercise in patients with COPD. Ninety-three women and 93 men with COPD matched for age and disease severity were evaluated during symptom-limited constant-work rate cycle exercise at 75% of peak capacity. Breathing pattern, inspiratory capacity, dyspnoea and leg discomfort Borg scores were recorded during exercise. Endurance time was shorter in women compared to men. Inspiratory capacity decreased at a similar rate during exercise in women and men (0.71 vs. 0.81 ml x s(- 1) for women and men respectively, p = 0.47) despite lower ventilation at end-exercise in women. At end-exercise, women showed lower inspiratory reserve volume (p < 0.005). Dyspnoea responses during exercise occurred with a steep rise near end-exercise, when inspiratory reserve volume approached a critical value, at 10% of total lung capacity, this onset of dyspnoea acceleration occurred earlier in women (p < 0.0001). At the same relative exercise intensity, women with COPD had lower endurance time than men. Compared to men, women with COPD were disadvantaged during exercise as they reached a critical inspiratory reserve volume earlier, leading to a steep increase in dyspnoea and to exercise termination.

Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD.

During constant-work-rate exercise in chronic obstructive pulmonary disease, dyspnea increases steeply once inspiratory reserve volume (IRV) falls to a critical level that prevents further expansion of tidal volume (Vt). We studied the effects of this mechanical restriction on the quality and intensity of exertional dyspnea and examined the impact of an anticholinergic bronchodilator. In a randomized, double-blind, crossover study, 18 patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 s = 40 +/- 3%predicted; mean +/- SE) inhaled tiotropium 18 mug or placebo once daily for 7-10 days each. Pulmonary function tests and symptom-limited cycle exercise at 75% of each patient's maximal work capacity were performed 2 h after dosing. Dyspnea intensity (Borg scale), operating lung volumes, breathing pattern, and esophageal pressure (n = 11) were measured during exercise. Dynamic hyperinflation reached its maximal value early in exercise and was associated with only mild increases in dyspnea intensity and the effort-displacement ratio, which is defined as the ratio between tidal swings of esophageal pressure (expressed relative to maximum inspiratory pressure) and Vt (expressed relative to predicted vital capacity). After a minimal IRV of 0.5 +/- 0.1 liter was reached, both dyspnea and the effort-displacement ratio rose steeply until an intolerable level was reached. Tiotropium did not alter dyspnea-IRV relationships, but the increase in resting and exercise inspiratory capacity was associated with an improved effort-displacement ratio throughout exercise. Once a critically low IRV was reached during exercise, dyspnea rose with the disparity between respiratory effort and the Vt response. Changes in dyspnea intensity after tiotropium were positively correlated with changes in this index of neuromechanical coupling.

The effect of tautomeric constant on the specificity of nucleotide incorporation during DNA replication: support for the rare tautomer hypothesis of substitution mutagenesis.

The nucleoside analogue dP (6-(2-deoxy-beta-D-ribofuranosyl)-3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-2-one) displays ambivalent hydrogen bonding characteristics whereby the imino tautomer of P can base-pair with adenine and its amino tautomer can base-pair with guanine. Fixed imino and amino tautomers of 6-methyl-3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-2-one (N-methyl P) have been synthesised and their structures obtained by X-ray crystallography. The tautomeric constant of N-methyl P has been calculated from pK(a) values of the fixed tautomers and the kinetic parameters for the incorporation of its 5'-triphosphate (dPTP) by exonuclease-free Klenow fragment of DNA polymerase I have been determined. A strong correlation between the tautomeric constant and the incorporation specificity of dPTP is found. These results lend support to the proposal that the minor tautomeric forms of the natural bases may play an important role in substitution mutagenesis during DNA replication. Furthermore, they imply that DNA polymerases impose specific steric requirements on the base-pair during nucleotide incorporation.

Efficacy and safety of the long-acting ß2-agonist olodaterol over 4 weeks in Japanese patients with chronic obstructive pulmonary disease.

BACKGROUND: Olodaterol is a novel long-acting ß2-agonist with proven ≥24-hour duration of action in preclinical and clinical studies. OBJECTIVE: This randomized, double-blind, placebo-controlled, parallel-group study evaluated the dose response of once-daily (QD) olodaterol based on bronchodilator efficacy, safety, and pharmacokinetics over 4 weeks in Japanese patients with chronic obstructive pulmonary disease (COPD). METHODS: All eligible patients were randomized to receive 2 µg, 5 µg, or 10 µg of olodaterol or placebo for 4 weeks via the Respimat Soft Mist inhaler. The primary end point was the change from baseline in trough forced expiratory volume in 1 second (FEV1) after 4 weeks of olodaterol treatment. Secondary end points included trough FEV1 after 1 week and 2 weeks of treatment, FEV1 area under the curve from 0 hour to 3 hours (AUC(0-3)), peak FEV1 from 0 hour to 3 hours (peak FEV1), and corresponding forced vital capacity (FVC) responses. Rescue medication use, COPD symptoms, physician global evaluation, pharmacokinetics, and safety were also assessed. RESULTS: A total of 328 patients with COPD were randomized to receive treatment. All olodaterol doses assessed in the study showed statistically significant increases in trough FEV1 compared to placebo at Day 29 (P<0.0001). Mean increases in peak FEV1 and FEV1 AUC(0-3) compared to placebo were also significant (P<0.0001). A clear dose-response relationship was observed across all treatment groups. FVC responses (trough and FVC AUC(0-3)) supported FEV1 outcomes. All doses of olodaterol were well tolerated, and no safety concerns were identified. CONCLUSION: QD olodaterol demonstrated 24-hour bronchodilator efficacy and was well tolerated in Japanese patients with COPD. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00824382.

A randomised, placebo-controlled, Phase II, dose-ranging trial of once-daily treatment with olodaterol, a novel long-acting ß2-agonist, for 4 weeks in patients with chronic obstructive pulmonary disease.

BACKGROUND: Olodaterol is a novel long-acting ß2-agonist (LABA) with ≥24-h duration of action in preclinical and clinical studies. OBJECTIVE: This Phase II, multicentre, randomised, double-blind, placebo-controlled, parallel-group, dose-finding study evaluated four doses of once-daily olodaterol over 4 weeks in patients with chronic obstructive pulmonary disease (COPD), based on efficacy, safety and pharmacokinetic parameters. METHODS: Patients received olodaterol inhalation solution or placebo via Respimat® Soft Mist™ inhaler once daily for 4 weeks. Pulmonary function testing was performed pre-dose (trough) and up to 3 or 6 h post-dose, depending on visit. Primary end point was change from baseline in trough forced expiratory volume in 1 s (FEV1) after 4 weeks' treatment. Secondary end points included change from baseline in peak FEV1 and FEV1 area under the curve from 0 to 6 h. RESULTS: 405 patients with COPD were randomised and assigned to treatment. Mean baseline post-bronchodilator FEV1 was 1.50 L (54% predicted). All olodaterol doses provided statistically significant increases in trough FEV1 compared to placebo (2 µg: 0.061 L [p = 0.0233]; 5 µg: 0.097 L [p = 0.0003]; 10 µg: 0.123 L [p < 0.0001]; 20 µg: 0.132 L [p < 0.0001]). A clear dose-response relationship was demonstrated regarding pulmonary function; the two highest olodaterol doses (10 and 20 µg) formed the plateau of the dose-response curve. All olodaterol doses were well tolerated, with no dose-dependent safety effects. CONCLUSION: Once-daily olodaterol demonstrated 24-h bronchodilator efficacy, confirming its potential as a once-daily LABA for the management of COPD. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00452400.

A randomised, double-blind, four-way, crossover trial comparing the 24-h FEV1 profile for once-daily versus twice-daily treatment with olodaterol, a novel long-acting ß2-agonist, in patients with chronic obstructive pulmonary disease.

BACKGROUND: This randomised, double-blind, four-way, crossover, Phase II study compared the 24-h forced expiratory volume in 1 s (FEV1) profile of alternative dosing frequencies of two total daily doses of olodaterol (5 and 10 µg) in patients with chronic obstructive pulmonary disease (COPD). METHODS: Patients received olodaterol 2 µg twice daily (BID), 5 µg BID, 5 µg once daily (QD) and 10 µg QD in a randomised sequence over 3-week treatment periods. Co-primary end points were FEV1 area under the curve from 0 to 12 h (AUC0-12) and area under the curve from 12 to 24 h (AUC12-24) responses. Additional lung-function responses, pharmacokinetics and safety were assessed. RESULTS: 47 patients were treated. All olodaterol doses provided significant increases in FEV1 versus baseline (p < 0.001) and FEV1 time profiles were nearly identical for olodaterol 5 and 10 µg QD. Olodaterol 5 µg QD demonstrated improved FEV1 AUC0-12 and similar AUC12-24 versus 2 µg BID. Olodaterol 5 µg QD showed slightly increased FEV1 AUC0-12 but lower AUC12-24 compared to 5 µg BID. Bronchodilation over 24 h was similar for olodaterol 5 µg QD and BID. All doses were well tolerated. CONCLUSIONS: Olodaterol 5 µg QD is efficacious in COPD, with a superior bronchodilatory profile compared to 2 µg BID, which is close to the same total daily dose, and a similar degree of bronchodilation over 24 h compared with double the daily dose (administered as 10 µg QD or 5 µg BID). TRIAL REGISTRATION: ClinicalTrials.gov: NCT00846768.

Recognition of base-pairing by DNA polymerases during nucleotide incorporation: the properties of the mutagenic nucleotide dPTP alphaS.

The highly mutagenic nucleoside dP (6-(2-deoxy-beta-D-erythro-pentofuranosyl)-3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-2-one) is a bicyclic analogue of N4-methoxy-2'-deoxycytidine. It exists as a mixture of its imino and amino tautomers in solution with a ratio of about 10:1 based on its tautomeric constant. The bicyclic nature of the heterocycle P restrains the amino substituent in an anti conformation and permits effective Watson-Crick base-pairing using either tautomer. The specificity of incorporation of dP by the 3'-5'-exonuclease-free Klenow fragment of DNA polymerase I (exo-free Klenow) has been studied using the 5'-(1-thio)triphosphate dPTP alphaS in combination with phosphorothioate-specific sequencing of the DNA products. The method provides a convenient qualitative assay for studying nucleotide incorporation and reveals for the first time a potential role for the minor tautomeric forms of the natural DNA bases in base misinsertion (substitution mutagenesis) during replication.