The bronchodilator response to salmeterol is maintained with regular, long-term use in patients with COPD

Long-acting beta(2)-agonists (LABAs) are recommended in the management of patients with chronic obstructive pulmonary disease (COPD). Previous studies have demonstrated that the LABA, salmeterol, improves lung function, symptoms and quality of life in patients with COPD. In this study, we have performed additional analyses of the combined data from two previous double-blind, placebo-controlled, parallel studies of salmeterol (50 microg, b.i.d) in patients with COPD. The new analyses reveal that the significant improvements seen in pre-dose and 2-h post-dose forced expiratory volume in 1 s (FEV(1)) compared to placebo, occur early in the treatment period, and are sustained for at least 24 weeks. Moreover, improvements in peak expiratory flow rate occur as early as Day 1, and are sustained throughout the 24-week period. Additional analyses of 12-h FEV(1) data also show that salmeterol is associated with an increase in the area under the curve at Week 12 compared with Day 1, adding further support to evidence that it results in a sustained bronchodilator response, with no evidence of tolerance.

Effect of antioxidant supplementation on ozone-induced lung injury in human subjects

To determine whether antioxidants can influence human susceptibility to ozone (O(3))-induced changes in lung function and airway inflammation, we placed 31 healthy nonsmoking adults (18 to 35 yr old) on a diet low in ascorbate for 3 wk. At 1 wk, subjects were exposed to filtered air for 2 h while exercising (20 L/min/m(2)), and then underwent bronchoalveolar lavage (BAL) and were randomly assigned to receive either a placebo or 250 mg of vitamin C, 50 IU of alpha-tocopherol, and 12 oz of vegetable cocktail daily for 2 wk. Subjects were then exposed to 0.4 ppm O(3) for 2 h and underwent a second BAL. On the day of the O(3) exposure, supplemented subjects were found to have significantly increased levels of plasma ascorbate, tocopherols, and carotenoids as compared with those of the placebo group. Pulmonary function testing showed that O(3)-induced reductions in FEV(1) and FVC were 30% and 24% smaller, respectively, in the supplemented cohort. In contrast, the inflammatory response to O(3) inhalation, as represented by the percent neutrophils and the concentration of interleukin-6 recovered in the BAL fluid at 1 h after O(3) exposure was not different for the two groups. These data suggest that dietary antioxidants protect against O(3)-induced pulmonary function decrements in humans.

Increased specific airway reactivity of persons with mild allergic asthma after 7.6 hours of exposure to 0.16 ppm ozone

BACKGROUND

Exposure to ozone causes decrements in lung function, increased airway reactivity to nonspecific bronchoconstrictors, and lung inflammation. Epidemiology studies show an association between ambient oxidant levels and increased asthma attacks and hospital admissions.

OBJECTIVE

The purpose of our study was to evaluate the response of persons with mild asthma to inhaled allergen after ozone exposure conditions similar to those observed in urban areas of the United States.

METHODS

Using a double-blind, counter-balanced design, we exposed 9 (5 women and 4 men) subjects with mild atopic asthma (house dust mite sensitive) to clean air and to 0.16 ppm ozone for 7.6 hours; exposures were separated by a minimum of 4 weeks. During exposure, subjects performed light exercise (ventilation = 24 L/min) for 50 minutes of each hour, and pulmonary function was evaluated before and after exposures. The morning after exposure, subjects underwent bronchial challenge with inhaled house dust mite allergen (Dermatophagoides farinae). Using a series of doubling allergen concentrations, subjects inhaled 5 breaths of nebulized allergen (0.06 to 500 AU/mL) at 10-minute intervals until a minimum of a 20% decrement in FEV(1) was elicited.

RESULTS

Compared with the change in FEV(1) during air exposure, there was a mean 9.1% +/- 2.5% (SEM) decrement in FEV(1) observed because of ozone (P <.01). Seven of the 9 subjects required less allergen after ozone exposure than after air exposure; there was a 0.58 mean dose shift in the doubling concentration of allergen attributable to the ozone exposure (P =.03).

CONCLUSION

These findings indicate that exposure of subjects with mild atopic asthma to ozone at levels sufficient to cause modest decrements in lung function also increases the reactivity to allergen. To the extent that this effect occurs in response to ambient exposures, ozone may be contributing to the aggravation of asthma.

Aminoguanidine inhibits inducible NOS and reverses cardiac dysfunction late after ischemia and reperfusion--implications for iNOS-mediated myocardial stunning

BACKGROUND

The functional significance of inducible nitric oxide synthase (iNOS) activation in response to myocardial ischemia and reperfusion (I/R) was investigated.

METHODS

New Zealand rabbits were randomly treated with either placebo, aminoguanidine (AMG; selective iNOS inhibitor), or L-arginine. Left-ventricular hemodynamics and myocardial blood flow were measured before coronary occlusion and 30 minutes and 48 h after initiation of reperfusion.

RESULTS

I/R resulted in left-ventricular dysfunction and increased myocardial iNOS activity. Placebo treatment had no effects on myocardial function. However, AMG significantly inhibited iNOS activity, significantly improved left-ventricular maximum + dP/dt and decreased LVEDP, whereas administration of L-arginine reduced + dP/dt and slightly increased LVEDP, compared to AMG-treated animals. Myocardial blood flow in the affected myocardium significantly increased after both AMG and L-arginine.

CONCLUSIONS

The present data indicate that induction of myocardial iNOS after 48 h I/R contributes to the development of reversible left-ventricular dysfunction, suggesting the involvement of iNOS in myocardial stunning. Whereas L-arginine is associated with further reduction of left-ventricular contractility, continuous inhibition of iNOS activation by AMG improves left-ventricular performance; this may be a novel and clinically important therapeutic modality in certain disease states associated with I/R, including cardiac operations using extracorporeal circulation and coronary angioplastic procedures.

Action of phosphatidylinositol-specific phospholipase Cgamma1 on soluble and micellar substrates. Separating effects on catalysis from modulation of the surface

The kinetics of PI-PLCgamma1 toward a water-soluble substrate (inositol 1,2-cyclic phosphate, cIP) and phosphatidylinositol (PI) in detergent mixed micelles were monitored by 31P NMR spectroscopy. That cIP is also a substrate (Km = approximately 15 mM) implies a two-step mechanism (intramolecular phosphotransferase reaction to form cIP followed by cyclic phosphodiesterase activity to form inositol-1-phosphate (I-1-P)). PI is cleaved by PI-PLCgamma1 to form cIP and I-1-P with the enzyme specific activity and ratio of products (cIP/I-1-P) regulated by assay temperature, pH, Ca2+, and other amphiphilic additives. Cleavage of both cIP and PI by the enzyme is optimal at pH 5. The effect of Ca2+ on PI-PLCgamma1 activity is unique compared with other isozymes enzymes: Ca2+ is necessary for the activity and low Ca2+ activates the enzyme; however, high Ca2+ inhibits PI-PLCgamma1 hydrolysis of phosphoinositides (but not cIP) with the extent of inhibition dependent on pH, substrate identity (cIP or PI), substrate presentation (e.g. detergent matrix), and substrate surface concentration. This inhibition of PI-PLCgamma1 by high Ca2+ is proposed to derive from the divalent metal ion-inducing clustering of the PI and reducing its accessibility to the enzyme. Amphiphilic additives such as phosphatidic acid, fatty acid, and sodium dodecylsulfate enhance PI cleavage in micelles at pH 7.5 but not at pH 5.0; they have no effect on cIP hydrolysis at either pH value. These different kinetic patterns are used to propose a model for regulation of the enzyme. A key hypothesis is that there is a pH-dependent conformational change in the enzyme that controls accessibility of the active site to both water-soluble cIP and interfacially organized PI. The low activity enzyme at pH 7.5 can be activated by PA (or phosphorylation by tyrosine kinase). However, this activation requires lipophilic substrate (PI) present because cIP hydrolysis is not enhanced in the presence of PA.

Prolonged acute exposure to 0.16 ppm ozone induces eosinophilic airway inflammation in asthmatic subjects with allergies

BACKGROUND

Increased ambient ozone levels have been associated with increased asthma morbidity in epidemiologic studies. Given that asthma is characterized by airway inflammation and increased sensitivity to airway irritants, it has been suggested that asthmatic subjects may be particularly sensitive to the effect of ozone.

OBJECTIVE

The objective of this study was to determine whether exposure to 0.16 ppm ozone induces eosinophilic inflammation in the lower airways of asthmatic subjects.

METHODS

Eight asthmatic subjects sensitive to mites were exposed to 0.16 ppm ozone and clean air on separate occasions no less than 4 weeks apart in a double-blind, randomized fashion followed by bronchoscopy 18 hours later. Bronchoalveolar lavage fluid and bronchial lavage fluid were examined for eosinophils.

RESULTS

Ozone induced significant increases in airway eosinophils, especially in bronchial lavage fluid.

CONCLUSIONS

Ozone exposure results in increased eosinophilic inflammation in the lower airways of asthmatic subjects with allergies.

Selective modulation of inducible nitric oxide synthase isozyme in myocardial infarction

BACKGROUND

Inducible nitric oxide synthase (iNOS) is activated in cardiac disorders. We investigated the contribution of increased iNOS activity to the development of left ventricular dysfunction after myocardial infarction by selective inhibition of the isozyme.

METHODS AND RESULTS

Male New Zealand rabbits were subjected to myocardial infarction. Animals were treated with either saline, S-methylisothiourea sulfate (SMT) (a selective iNOS inhibitor), or N(omega)-nitro-L-arginine (L-NNA) (a nonselective NOS inhibitor). Inducible and constitutive NOS (cNOS) activity, plasma NO(x), cGMP, hemodynamics, and myocardial blood flow were measured before and 5, 24, and 72 hours after coronary occlusion. Infarction 72 hours after occlusion resulted in increased myocardial iNOS activity, increased cardiac NO(x) production, and elevated cGMP levels. cNOS remained unchanged. Infarction increased left ventricular end-diastolic pressure (LVEDP) and decreased maximum +dP/dt and -dP/dt. L-NNA inhibited iNOS and cNOS activities and plasma NO(x) levels. L-NNA further increased LVEDP and reduced myocardial blood flow. Administration of SMT 72 hours after infarction significantly inhibited iNOS and cardiac NO(x) production but had no effects on cNOS. SMT improved left ventricular maximum +dP/dt and -dP/dt and decreased LVEDP. Myocardial blood flow in the remote myocardium increased.

CONCLUSIONS

These findings suggest that induction of iNOS activity 72 hours after infarction exerts negative inotropic effects and contributes to the development of myocardial dysfunction; selective modulation of increased iNOS activity by SMT improves cardiac performance, enhances myocardial blood flow, and may be beneficial in the treatment of acute myocardial infarction.

Essential role of the tyrosine kinase substrate phospholipase C-gamma1 in mammalian growth and development

The activation of many tyrosine kinases leads to the phosphorylation and activation of phospholipase C-gamma1 (PLC-gamma1). To examine the biological function of this protein, homologous recombination has been used to selectively disrupt the Plcg1 gene in mice. Homozygous disruption of Plcg1 results in embryonic lethality at approximately embryonic day (E) 9.0. Histological analysis indicates that Plcg1 (-/-) embryos appear normal at E 8.5 but fail to continue normal development and growth beyond E 8.5-E9.0. These results clearly demonstrate that PLC-gamma1 with, by inference, its capacity to mobilize second messenger molecules is an essential signal transducing molecule whose absence is not compensated by other signaling pathways or other genes encoding PLC isozymes.

Pulmonary functions of school children in highly polluted northern Bohemia

The purpose of this study was to ascertain whether pulmonary function in children who were lifetime residents of the highly polluted district of Teplice in northern Bohemia was lower than that for children who were lifetime residents of the cleaner district of Prachatice in southern Bohemia. Forced expiratory spirometry was measured twice (February/March and April) in approximately 235 eighth-grade students in each district. On both testing occasions, height-adjusted forced expiratory volume in 1 s and forced expiratory flow between 25% and 75% forced vital capacity were significantly lower (p < .001) in children from Teplice than in those from Prachatice. These differences were not associated with parental smoking habits, presence of pets, heating/cooking fuels, private home/apartment residency, or rural/urban residency. In Teplice, no differences were observed between lung functions measured at the end of the high pollution season (February/March) and those measured after the children breathed much cleaner air for a 4-wk period (April). This result was suggestive of a condition of chronically depressed lung function. No differences across times were observed in Prachatice, indicating that our measurements were reliable.

S-methylisothiourea inhibits inducible nitric oxide synthase and improves left ventricular performance after acute myocardial infarction

The contribution of increased inducible nitric oxide synthase (iNOS) activity to the development of left ventricular dysfunction after acute myocardial infarction (MI) was investigated New Zealand rabbits (n = 24) were randomly treated with either saline, S-methylisothiourea sulfate (SMT; selective iNOS inhibitor) or N-omega-nitro-L-arginine (NOLA; non-isoform selective NOS inhibitor). Left ventricular hemodynamics and myocardial blood flow were measured before coronary occlusion and on postoperative day 3 (POD 3). MI resulted in left ventricular dysfunction and increased myocardial iNOS activity. SMT and NOLA significantly inhibited iNOS activity; SMT, but not NOLA, significantly improved left ventricular maximum +dP/dt and decreased LVEDP; myocardial blood flow in the remote myocardium significantly increased after SMT. Induction of myocardial iNOS after MI on POD 3 contributes to the development of left ventricular dysfunction; modulation of iNOS activity by SMT improves left ventricular performance and may be beneficial after acute MI.

Teplice program--the impact of air pollution on human health

The aim of the Teplice Program is to investigate and assess the impact of air pollution on the health of the population in the district of Teplice, Czech Republic. Characterization of the air pollutants demonstrated unusually high concentrations during winter inversions of fine particles dominated by acidic sulfates, genotoxic organic compounds, and toxic trace elements. The major source of airborne fine particles is the burning of coal for heating and power. Human exposure and biomarker studies demonstrated large seasonal variations in air pollution within the Teplice District and higher seasonal average pollution levels than the comparative district, Prachatice. Personal exposures to fine particles and organic carcinogens [e.g., polycyclic aromatic hydrocarbons (PAH)] were correlated with excretion of PAH metabolites in urine, several trace metals in blood, and DNA adducts in white blood cells. Respiratory and neurobehavioral studies of school children were conducted using questionnaires and clinical measures. A significantly higher prevalence of adverse respiratory symptoms and decreased lung function were found in the Teplice district than in Prachatice. The neurobehavioral studies indicated significantly higher teacher referrals for clinical assessment in Teplice, but the majority of objective performance measures did not differ. Reproductive studies were conducted in both males and females. A study of the effects of exposure on pregnancy and birth found an excess prevalence of low birth weight and premature births in Teplice; these adverse effects were more common in infants conceived in the winter and whose mothers were smokers. Based on questionnaires and medical examination, the reproductive development of young men was not different between districts and seasons, however, measures of semen quality suggest that exposure to high levels of air pollution are associated with transient decrements in semen quality.

Effect of inhibitors of inducible form of nitric oxide synthase in infarcted heart muscle

Nitric oxide (NO), an unstable radical, is synthesized from L-arginine by the constitutive (cNOS) and inducible (iNOS) forms of NOS. cNOS is present mainly in endothelial cells and plays a role in the regulation of blood flow. iNOS, the dominant enzyme in heart muscle during myocardial infarction, allograft rejection, and cardiomyopathy, is activated in macrophages. We recently described a significant increase of iNOS activity in macrophages of infarcted rabbit myocardium 24 hours after coronary occlusion, with peak activity occurring 3 days following coronary artery ligation. Inhibitors of NOS are L-arginine derivatives that inhibit both cNOS and iNOS; S-methylisothiourea (SMT) and aminoguanidine (AMG) are specific inhibitors of iNOS. Cyclosporin A and dexamethasone inhibit by interfering with protein synthesis. iNOS inhibition by SMT, NG-nitro-L-arginine (L-NNA), AMG, cyclosporin A and dexamethasone was examined in homogenates of normal, risk and infarcted myocardium. Three days after coronary artery ligation, the heart was excised and divided into normal, risk and infarcted regions. The inhibitory effect was calculated as IC50. Results shows that SMT was the most potent inhibitor with the lowest IC50; its effect, as well as the effects of L-NNA and AMG, depended on the location in the myocardium. Inhibition for SMT and AMG was greater in the normal area than in the risk and infarcted regions. AMG induced an initial rise of iNOS followed by gradual decline in the area of risk and infarction. No inhibitory effects in cyclosporin A and dexamethasone were noted.

Lack of effect of low levels of carboxyhemoglobin on cardiovascular function in patients with ischemic heart disease

We studied 30 patients 38-75 yr of age who had ischemic heart disease to assess the effect of acute elevation of carboxyhemoglobin (COHb) concentration. Patients were nonsmokers with ischemia defined by exercise-induced ST depression (ST decreases)--25/30, angina--23/30, or abnormal ejection fraction (EF) response--18/30. After an initial familiarization and exercise session patients were exposed to air (carboxyhemoglobin [COHb] = 1.5 +/- 0.05%) and to carbon monoxide (CO) (100 ppm-COHb-average = 3.8 +/- 0.1%) on successive days in a double blind, randomized fashion. There was no significant difference in time to onset of angina (air = 312 sec, CO = 306 sec), maximal exercise time (air = 711 sec, CO = 702 sec), maximal ST decreases (1.5 mm for both), or time to significant ST decreases (air = 474 sec, CO = 475 sec). Double product at ST decreases and maximal double products were similar for both conditions. Resting ejection fraction was slightly but nonsignificantly higher after CO exposure (air = 53.9%, CO = 55.2%). Maximal ejection fraction was similar for both conditions (air = 57.4%, CO = 57.1%). Change in ejection fraction was slightly lower for CO exposure (air = 3.5%, CO = 2%), p = .049. In conclusion, there is no clinically significant effect of 3.8% COHb (representing a 2.2% increase from resting values) on the cardiovascular system in this study.

Airway sensitivity of asthmatics to sulfur dioxide

The purpose of this study was to describe for asthmatic subjects the distribution of individual bronchial sensitivity to sulfur dioxide (SO2). Subjects were nonsmoking male asthmatics (n = 27) who were sensitive to inhaled methacholine. None of the subjects used corticosteroids or cromolyn sodium. Oral medications were withheld for 48 hr, inhaled medications for 12 hr prior to all testing. Each subject participated in four separate randomly ordered 10 min exposures to 0.00, 0.25, 0.50 and 1.00 ppm SO2 at 26 degrees C, 70% relative humidity. During exposures, subjects breathed naturally and performed moderate exercise (VE, normalized for body surface area = 21 1/m2 X min). Before and 3 min after exposure, specific airway resistance (SRaw) was measured by body plethysmography. Those subjects whose SRaw was not doubled by exposure to 1.00 ppm were also exposed to 2.00 ppm SO2. Dose response curves (relative change in SRaw, corrected for change in clean air vs SO2 concentration) were constructed for each subject. Bronchial sensitivity to SO2 [PC(SO2)], defined as the concentration of SO2 which provoked an increase in SRaw 100% greater than the response to clean air, was determined. Substantial variability in sensitivity was observed: for 23 subjects, PC(SO2) ranged between 0.28 and 1.90 ppm, while for the remaining 4 subjects, it was greater than 2.00 ppm SO2. The median PC(SO2) was 0.75 ppm SO2, and 6 subjects had a PC(SO2) of less than 0.50 ppm. PC(SO2) was not related (r = 0.31) to airway sensitivity to methacholine.

Avidin-biotin affinity chromatography: application to the isolation of human placental insulin receptor

The ligand N alpha, B1-(6-biotinylamido)hexanoyl-insulin was attached noncovalently to Sepharose 4B immobilized succinoylavidin to form an insulin-affinity resin. This resin was used to isolate highly purified insulin receptor from human placental tissue by a four step process involving (i) preparation of a crude membrane fraction, (ii) solubilization with Triton X-100, (iii) wheat germ agglutinin purification, and (iv) insulin-affinity chromatography. NaDodSO4/PAGE of the purified 125I-labeled receptor under nonreducing conditions showed the presence of a major component with an approximate molecular weight of 350,000 and a minor component with a molecular weight of approximately equal to 166,000. Based on the assumption that the degree of labeling is comparable in both components, the material corresponding to the Mr 350,000 peak represents approximately equal to 94% of the receptor preparation as determined by scanning the autoradiograms. The specific insulin binding capacity of the preparation is 18 +/- 6 micrograms of 125I-labeled insulin per mg of protein as determined by the polyethylene glycol assay and analyzed by Scatchard plot. Insulin binding activity was stable at 4 degrees C and pH 7.6 for at least 12 weeks but was destroyed by freezing and thawing. The availability of highly purified receptor afforded the opportunity to explore its precipitability by polyethylene glycol under assay conditions. Whereas trichloroacetic acid precipitated 95% of the 125I-labeled receptor, polyethylene glycol precipitated only 30%. If the specific activity of the receptor is corrected for incomplete precipitability by polyethylene glycol, the apparent specific binding would be 3.5 +/- 1.2 mol of insulin per mol of receptor. These results are in disagreement with the current receptor model, which postulates that 1 mol of receptor (Mr, 350,000) binds 2 mol of insulin. Clearly, the problems associated with the method available for determining insulin binding are sufficiently serious to preclude their use in determining receptor valence.

Albumin-induced plasma volume expansion: diurnal and temperature effects

To develop a reliable procedure for the acute expansion of plasma volume (PV), 26 male volunteers were randomly assigned to either a thermoneutral (25 degrees C and 40% relative humidity) or hot-dry (37 degrees C and 25% relative humidity) environment; subsequently each subject was seated for at least 1 h and then infused intravenously with either 100 or 200 ml of a 25% albumin solution or 0.9% saline. On the day before each infusion, PV was estimated by dye dilution using indocyanine green. Net percent change in PV (using hematocrit and hemoglobin values) was calculated at 1, 3, 6, 9, 12, and 24 h postinfusion. The PV of subjects residing in the heat after a 100-ml saline infusion increased significantly over 1-h values at 6, 9, and 12 h postinfusion but not at 24 h. The same trend, although not significant, was apparent at room temperature. The data suggest a slow isooncotic circadian pattern of PV expansion and contraction. The infusion of hyperoncotic albumin produced rapid expansion of plasma volume. With the low dose (25 g) at 1 h postinfusion, the expansion was 379 +/- 102 ml in the heat and 301 +/- 160 ml at room temperature. With the high dose (50 g) at 1 h postinfusion, the expansion was 479 +/- 84 ml in the heat and 427 +/- 147 ml at room temperature. The high dose produced an expansion that persisted for at least 9 h in subjects in either environment. The data suggest a mechanism for the retention of fluid during heat acclimatization and a useful procedure for plasma volume expansion in humans.

Effects of submicronic sulfuric acid aerosol on human pulmonary function

The effects of a 4-hr exposure in an environmental chamber to an average 108 micrograms/m3 sulfuric acid (H2SO4 (MMAD, 0.5 micrograms)] on pulmonary function were examined in healthy young men. Subjects were randomly assigned to either experimental (N = 18) or control (N = 17) groups. All subjects were exposed to clean air on the first day. On the second day, experimental subjects were exposed to H2SO4 while control subjects were re-exposed to air. Subjects exercised for 15 min at 1.5 and 3.5 hr of exposure at an intensity equivalent to 75% of predicted maximal heart rate. Ventilation was monitored during the initial 14 min of each exposure. Pulmonary function was assessed prior to, and 2 hr and 4 hr of each exposure. Exposure to H2SO4 had no significant effect on minute ventilation, respiratory frequency, or tidal volume, nor did it affect pulmonary function as assessed by measures of airway resistance, specific airway conductance, forced vital capacity (FVC), forced expiratory flow in 1 sec (FEV 1.0), FEV 1.0/FVC, mean expiratory flow rate between 25% and 75% FVC, and expiratory flow rate at 50% and 25% FVC. It was concluded that no changes in pulmonary function resulted from exposure to H2SO4 under the above conditions.