Alpha-1 antitrypsin limits neutrophil extracellular trap disruption of airway epithelial barrier function

Neutrophil extracellular traps contribute to lung injury in cystic fibrosis and asthma, but the mechanisms are poorly understood. We sought to understand the impact of human NETs on barrier function in primary human bronchial epithelial and a human airway epithelial cell line. We demonstrate that NETs disrupt airway epithelial barrier function by decreasing transepithelial electrical resistance and increasing paracellular flux, partially by NET-induced airway cell apoptosis. NETs selectively impact the expression of tight junction genes claudins 4, 8 and 11. Bronchial epithelia exposed to NETs demonstrate visible gaps in E-cadherin staining, a decrease in full-length E-cadherin protein and the appearance of cleaved E-cadherin peptides. Pretreatment of NETs with alpha-1 antitrypsin (A1AT) inhibits NET serine protease activity, limits E-cadherin cleavage, decreases bronchial cell apoptosis and preserves epithelial integrity. In conclusion, NETs disrupt human airway epithelial barrier function through bronchial cell death and degradation of E-cadherin, which are limited by exogenous A1AT.

Sex differences in the subjective and reinforcing effects of visual and olfactory cigarette smoke stimuli

Although nicotine intake clearly reinforces cigarette smoking behavior, non-nicotine smoke stimuli may become conditioned reinforcers of smoking. In Study 1, we compared the acute subjective and reinforcing effects of cigarette smoking in men and women under two conditions: blockade of visual and olfactory/taste smoke stimuli vs. no blockade. Subjective hedonic ratings of 'like puffs' and 'satisfying', but not 'strength', 'high in nicotine', or CO boost, were significantly reduced under the blockade vs. no blockade conditions. During subsequent ad lib puffing, significantly fewer puffs were self-administered under the blockade condition, particularly among women. In Study 2, we examined the influences of these stimuli separately and found that olfactory/taste stimuli, but not visual stimuli, reduced hedonic ratings and puff self-administration in women but not in men. In Study 3, procedures similar to those in Study 1 were used to examine whether this sex difference in responses to conditioned stimuli generalizes to a non-drug consummatory behavior, eating (pizza). However, hedonic ratings and ad lib consumption of pizza were substantially reduced in both men and women following blockade of visual and olfactory/taste food stimuli. These results indicate that the presumably conditioned stimuli of olfactory/taste from cigarette smoke may influence subjective hedonic ratings and reinforcement from smoking more in women than in men. However, this sex difference may not generalize beyond smoking or other drug reinforcement.

Threshold doses for nicotine discrimination in smokers and non-smokers

RATIONALE

Tobacco use during initial experimentation often involves modest nicotine exposure, escalating to larger doses and more frequent exposure with the onset of tobacco dependence. Threshold doses for nicotine discrimination therefore may differ between naive and experienced tobacco users.

OBJECTIVES

We determined the lowest (threshold) dose of nasal spray nicotine that smokers and non-smokers could reliably discriminate from placebo spray.

METHODS

Male and female smokers (n=18) and non-smokers (n=17) were initially trained to discriminate 20 microg/kg from placebo before proceeding to threshold determination sessions, which involved discrimination of progressively lower doses below 20 microg/kg ("descending order" subgroup) or higher doses above 1 microg/kg ("ascending order" subgroup). Threshold was determined by the lowest dose reliably discriminated from placebo (correct on > or =80% of testing trials) and by failure to discriminate the next lowest dose.

RESULTS

Threshold doses for nicotine discrimination were low and not different between smokers and non-smokers (median thresholds of 3 versus 2 microg/kg and approximate blood levels of 2.6 versus 1.6 ng/ml, respectively). Thresholds were similar between descending and ascending order subgroups. Several subjective responses differentiated threshold dose from the dose just below threshold, particularly in non-smokers.

CONCLUSIONS

Threshold doses for nasal spray nicotine discrimination in humans are low, well below the typical nicotine delivery of most cigarette brands, and may not change after long-term smoking exposure.

The discriminative stimulus and reinforcing effects of nicotine in humans following nicotine pretreatment

Smokers often report that the first cigarette of the day is the most rewarding, and subsequent smoking is less rewarding. Reduction in smoking enjoyment later in the day may be related to acute tolerance to the discriminative stimulus effects of nicotine. We examined changes in nicotine discrimination behaviour in humans as a function of acute nicotine pretreatment. Male and female dependent smokers (n = 15) were initially trained to discriminate 20 microg/kg nicotine by nasal spray from placebo (0 microg/kg) without nicotine pretreatment. They then were tested on generalization of discrimination across a range of spray doses from 0-20 microg/kg following pretreatment with placebo, moderate dose (14-21 mg) or high dose (28-42 mg) transdermal nicotine. Generalization testing involved both two- and three-response ('novel' option) quantitative procedures. Subjects also engaged in a self-administration phase at the end of each session, involving choices between nicotine (20 microg/kg) and placebo spray. Nicotine pretreatment significantly attenuated nicotine-appropriate responding at higher nicotine spray doses, suggesting acute tolerance, but only in women. Similar results were seen for subjective 'head rush', suggesting this effect may be related to discrimination behaviour in women. However, nicotine pretreatment also increased novel-appropriate responding, especially in men, following intermediate generalization doses, suggesting qualitatively different stimulus effects. Although differences were not significant, nicotine self-administration tended to be inversely associated with nicotine pretreatment dose in men but not in women. These results only modestly support the notion of acute tolerance to the discriminative stimulus effects of nicotine, and even then only in women and not in men.

Pharmacokinetics and bioavailability of a metformin/glyburide tablet administered alone and with food

Two randomized crossover studies were conducted to evaluate the pharmacokinetics (including food effect) of fixed-combination metformin/glyburide tablets. Pharmacokinetics and bioavailability of two strengths (500 mg/2.5 mg and 500 mg/5 mg) of metformin/glyburide tablets were assessed relative to coadministered metformin and glyburide tablets in study 1. The effect of a high-fat meal on the bioavailability of a metformin/glyburide (500 mg/5 mg) tablet was assessed relative to the fasted condition in study 2. The fixed combination metformin/glyburide tablets showed bioequivalence for the metformin component with the reference metformin tablet and comparable bioavailability for the glyburide component with the reference glyburide tablet. Food does not appear to affect the bioavailability of either component to an appreciable extent.

Microbial retention characteristics of 0.2-microns-rated nylon membrane filters during filtration of high viscosity fluids at high differential pressure and varied temperatures

Regulatory guidelines for aseptic manufacture of pharmaceuticals recommend validation of sterilizing filters by bacterial challenge under "worst case" conditions. The microbial retention characteristics of a sterilizing grade, 0.2-microns-rated Nylon 66 membrane filter were evaluated for filtration of high viscosity fluids. Glycerol (80%) was used as the carrier fluid and Pseudomonas diminuta ATCC 19146 as the challenge organism. Testing was carried out at a constant differential pressure of 60 psig over a six-hour test period. Test runs were undertaken at three different temperature conditions (25 +/- 5 degrees C, 42 +/- 1 degree C, and 50 +/- 1 degree C). Under the test conditions, the Nylon 66 membranes provided total retention of P. diminuta. The results demonstrated that a high pressure differential challenge using a high viscosity fluid over a six-hour test period at ambient and elevated temperatures did not alter the retention characteristics of the membrane filter.

Arrhythmogenic assessment of prenalterol in conscious dogs

Possible arrhythmogenic side-effects of the positive inotropic agent prenalterol were studied in conscious dogs, three to four days after coronary artery ligation. Prenalterol showed a propensity to cause arrhythmias in one out of eight dogs, thereby confirming published data from clinical studies.