Germline mutations in an intermediate chain dynein cause primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, autosomal recessive disorder caused by abnormal ciliary ultrastructure and function, characterized clinically by oto-sino-pulmonary disease. Mutations in an intermediate chain dynein (DNAI1; IC78) have recently been described in PCD patients, with outer dynein arm (ODA) defects. The aims of the current study were to test for novel DNAI1 mutations in 13 PCD patients with ODA defects (from 7 unrelated families) and to assess genotype/phenotype correlations in patients and family members. A previously reported mutation (219+3insT) was detected in three PCD patients from two families. The opposite allele had the novel missense mutation G1874C (W568S) in both affected individuals from one family, and a nonsense mutation G1875A (W568X) in an affected individual from another family. The tryptophan at position 568 is a highly conserved residue in the WD-repeat region, and a mutation is predicted to lead to abnormal folding of the protein and loss of function. None of these mutations were found in 32 other PCD patients with miscellaneous ciliary defects. Mutations in DNAI1 are causative for PCD with ODA defects, and are likely the genetic origin of clinical disease in some PCD patients with ultrastructural defects in the ODA.

Waste incineration and pulmonary function: an epidemiologic study of six communities

This study investigated the chronic effects of emissions from three different waste incinerators on pulmonary function of both healthy and sensitive subjects with chronic respiratory symptoms. Participants were 8-80 years old, not currently smoking, and living in one of three communities each with an incinerator or one of three matched comparison communities. In total, 1018 subjects underwent a spirometric test once a year during 1992-1994. Exposure was assessed by three methods: living in an incinerator community; distance from the incinerator; and an incinerator exposure index, a function of the distance and direction of each subject's residence to the incinerator, days downwind, and average time spent outdoors. The results generally showed no statistically significant association between pulmonary function and these three incinerators, adjustment for gas oven/range use at home, length of residency, and smoking history in the mixed linear models. Two significant associations were that exposure to the hazardous waste incinerator in 1994 and to the municipal waste incinerator in 1993 were related to poor forced vital capacity. Sensitive subjects were not more adversely affected by incineration emissions than were hay fever or normal subjects. Possible explanations for the negative findings are low exposure levels and bias due to nondifferential misclassification of exposures.

Eosinophil influx to the nasal airway after local, low-level LPS challenge in humans

BACKGROUND

Recent observations show that atopic asthmatic subjects have increased sensitivity to respirable endotoxin (or LPS) compared with normal persons. In vitro studies demonstrate that LPS enhances eosinophil survival. These observations suggest that the effects of inhaled LPS in asthmatic subjects may include increases in the number of airway eosinophils.

OBJECTIVE

We sought to determine whether low-level nasal LPS challenge causes an increase in eosinophil numbers in the nasal airways of atopic or normal subjects.

METHODS

Sixteen volunteers (10 atopic asthmatic subjects and 6 normal subjects) underwent 2 nasal challenge sessions. In one session, one nostril was challenged with saline and the other with 0. 1 microg of LPS. During the second session, 0.3 microg and 1.0 microg of LPS was delivered to each nostril, respectively. Nasal lavage fluid was obtained from each nostril before challenge, as well as 4 and 24 hours after challenge, and examined for the percent of total cells that were eosinophils and neutrophils, as well as cytokine levels.

RESULTS

LPS (1.0 microg) increased the percent of eosinophils in nasal lavage fluid 4 hours after challenge in atopic subjects only. There was also a correlation between constitutive nasal GM-CSF and eosinophil response to LPS in atopic subjects.

CONCLUSION

LPS challenge increases eosinophils in the airways of atopic subjects.

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.

Bronchoconstriction in asthmatics exposed to sulfur dioxide during repeated exercise

Young male volunteers with mild asthma and hypersensitivity to methacholine were exposed for 75 min with natural breathing to 0.0, 0.25, 0.5, and 1.0 ppm SO2. Each exposure included three 10-min periods of moderate treadmill exercise (minute ventilation 21 l . m-2 . min-1, O2 consumption 25 ml . kg-1, and heart rate 120/min). Specific airway resistance (sRaw) was not significantly increased after exercise in 0.25 ppm SO2, relative to the control exposure (clean air). In 0.5 and 1.0 ppm SO2, sRaw was increased twofold and threefold above preexposure levels, respectively, corresponding to increases of 3.2 and 9.2 cmH2O . s in excess over the increases seen in clean air (P less than 0.001). There was a broad range of responses to exercise and SO2. The increases in sRaw after the second and third exercises were significantly less than after the first exercise. Respiratory impedance measured by forced random noise suggests that the induced bronchoconstriction was primarily associated with peripheral airways. These results confirm that mild asthmatics selected for methacholine sensitivity have as a group significant bronchoconstriction in response to short-term moderate exercise with natural breathing in 1.0 and 0.5 ppm SO2. In addition, the induced bronchoconstriction is decreased after short-term repeated exercise in SO2.

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.

The mechanism of rapid shallow breathing due to histamine and phenyldiguanide in cats and rabbits

In anaesthetized cats and rabbits we analyzed the rapid shallow breathing following exposure to histamine aerosol (mainly an irritant receptor stimulant) and i.v. injection of phenyldiguanide (mainly a J receptor stimulant). Both drugs caused a marked leftward displacement of the tidal volume (VT) vs inspiratory time (TI) relationship (Hering-Breuer threshold curve) without a corresponding increase in inspiratory flow rate so that inspiration was cut off at a lower VT and TI. The leftward displacement of the VT vs TI relationship occurred with a great shortening of the duration of inspiration during occluded breaths (T0I) accompanied by a shortening of the expiratory phase (T0E). These parameters monitored the central respiratory rhythm in absence of the phasic lung volume related vagal loop. It is suggested that the increased central respiratory frequency was due to the augmented firing of fibers from stimulated irritant and J receptors. Stimulation of these endings also caused the TE vs TI relationship to become steeper in cats and to be displaced downwards in rabbits.

Respiratory effects of exposure to ozone plus sulfur dioxide in Southern Californians and Eastern Canadians

Volunteer subjects were exposed in an environmentally controlled chamber in Los Angeles to SO2 and O3, separately and in combination, to study the enhanced toxicity of the O3 + SO2 mixture observed in a previous study in Montreal. Toxic responses to O3 + SO2 were less severe than observed previously, and only slightly more severe than with O3 alone. Sulfur-containing aerosols formed by chemical reactions within the chamber air may have contributed to the O3 + SO2 responses in the Montreal study. Adaptation of Los Angeles residents to ambient O3 may also contribute to response variability.

Effect of SO2 on control of breathing in anesthetized cats

In seven anesthetized tracheotomized cats we studied the acute respiratory effects of SO2 inhalation at different steady-state levels of arterial CO2 tension (Paco2). During room air breathing, SO2 (0.05%) addition caused a progressive reduction in tidal volume (VT) and increases in both respiratory frequency (f) and pulmonary resistance (RL). Atropine sulfate abolished the bronchoconstriction response to SO2 and thus permitted the study of the influence of SO2 on VT and f in the absence of constricted airways. Despite marked reductions in the VT VS. PaCO2 relationships with SO2 exposure after atropine, the relationship between pulmonary ventilation (VE) and PaCO2 was not signifcantly altered. This was the case since SO2 caused solely a reduction in inspiratory duration (Ti), affecting neither the mean rate of rise of inspiratory activity (i.e., VT/Ti) nor the relationship between Ti and breath duration. Thus, airways irritation with SO2 produced rapid, shallow breathing characterized by a shortening of inspiratory and total respiratory cycle times with no change in the rate of development of inspiratory activity. The findings suggest an influence exclusively concerned with the timing of inspiration. Perhaps premature onset of inspiratory activity accounts for the observed effects.

Effects of ozone exposure in Canadians and Southern Californians. Evidence for adaptation?

Comparison of published reports on physiological effects of exposure to ozone (O3) suggests that Canadians are more reactive than southern Californians. Responses of subjects and experimental methods were compared in a cooperative investigation of this apparent difference in reactivity. Four Canadians and four Californians were exposed to 0.37 ppm O3 in purified air at 21 degrees C and 50% relative humidity for 2 hours with intermittent light exercise. Exposures to purified air alone served as controls. Responses of subjects were similar to those observed previously: Canadians on the average showed greater clinical and physiological reactivity to exposure than did Californians, who were no more than minimally reactive. Canadians also showed larger increases in erythrocyte fragility following exposure. No methodological differences sufficient to explain different results of previous studies were found. Although other possible explanations have not been ruled out entirely, adaptation of southern Californians to chronic ambient O3 exposure is a rational hypothesis to explain these results.

Problems in studies of human exposure to air pollutants

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