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Biomedical subjects

W G Reddan

Publications and source records attributed to W G Reddan.

32 records · Page 2Linked to original sources
PubMed1976

The value of precipitating antibodies in screening for hypersensitivity pneumonitis.

To evaluate the usefulness of precipitin tests as a screening method to detect hypersensitivity pneumonitis, we compared persons with precipitins to organic antigens with precipitin-negative subjects from the same population of 1,072 office workers participating in a health survey examination. Thirty-three of the 53 persons with preciptins to Micropolyspora faeni, Thermoactinomyces vulgaris, T. candidus, pigeon serum, aspergillus, alternaria, pullularia, penicillium, cephalosporium, trichoderma, and phoma were matched according to age, sex, height, and smoking habits with precipitin-negative subjects. The subjects completed a self-administered standard questionnaire, they were interviewed and examined, chest radiograms were taken, and pulmonary functions were evaluated at rest and during mild and moderate exercise. No significant differences were found between the 2 populations in any of the pulmonary function measurements. In addition, clinical and radiologic evidence failed to distinguish between the 2 groups. No cases of hypersensitivity pneumonitis were found. In this population, precipitins had no apparent relationship to long disease. The frequency of precipitins was considerably higher than the frequency of hypersensitivity pneumonitis. We concluded that the detection of hypersensitivity pneumonitis in population surveys attempting to establish prevalence of the disease cannot be accomplished by the simple analysis of serum precipitating antibodies but requires, in addition, a more complex analysis of historical, radiologic, and immunologic data.

Antigens↗
PubMed1976

Acute alterations in stroke volume during exercise at 3,100 m altitude.

Following 3 weeks exposure to an altitude of 3,100 m, the cardiac output response to upright submaximal exercise was examined in 3 healthy subjects breathing ambient air and breathing 60% oxygen. The procedure allowed acute alteration of the 2 conditions within a single testing period of 30 min, 60% oxygen breathing either preceding or following breathing ambient air. Cardiac output was also measured in two of the subjects during maximal exercise under these two conditions. Administration of the high oxygen inspirate during exercise had little effect on the level of cardiac output but resulted in an immediate bradycardia and a dramatic increase of approximately 16% in stroke volume. Stroke volumes during maximal exercise were also increased by approximately 10% by the administration of high oxygen. It is suggested that the condition of decreases exercise stroke volume which develops with chronic exposure to altitude may be largely the result of diminished myocardial contractility stemming from a condition of myocardial hypoxia.

Altitude↗
PubMed1975

Respiratory tract disease from thermosetting resins. Study of an outbreak in rubber tire workers.

An outbreak of upper and lower respiratory tract inflammatory disease and conjunctivitis among synthetic rubber tire workers occurred. The outbreak began after the introduction of a new thermosetting resin, containing resorcinol and a trimere of methylene aminoacetronitrile, into the rubber tire carcass stock formulation. Two hundred ten workers were affected. Characteristically, symptoms improved during periods of sick leave or vacation, recurring upon the workers' return to the plant. Chest radiograms disclosed pneumonic infiltrates in about one fourth of the cases. Pulmonary function studies detected abnormal airways dynamics as well as abnormal diffusing capacity in more than one third of the workers tested. Lung biopsy showed evidence of focal interstitial fibrosis and peribronchiolar and perivascular chronic inflammatory reaction. The illness was ascribed to volatile products released during the manufacture of synthetic rubber tires. The exact chemical nature of these products is unknown.

Adult↗
PubMed1973

Pulmonary gas exchange in nonnative residents of high altitude.

This study represented an initial attempt, by means of cross-sectional investigation, to determine the effects of chronic exposure to high altitude on pulmonary gas exchange. Single-breath D(Lco) and its components were determined at rest and during muscular work in two groups of healthy, non-smoking, sea level natives who had initiated 1-16 yr of residence at 3,100 m altitude either during physical maturation (at age 10+/-4 yr) or as adults (at age 26+/-4 yr). The relative degree of acclimatization achieved in these lowland residents was assessed through their comparison both with normal sea-level values and with two additional groups of short-term sojourners and natives to 3.100 m. D(Lco) at rest and work was significantly elevated above normal and above sojourner values in both groups of resident lowlanders at 3,100 m. The high D(Lco) in the native to 3,100 m was closely approximated in the younger resident lowlander at rest, but only during exercise in the adult resident lowlander. The high D(Lco) at rest and during exercise in the resident lowlanders was not attributable to differences in Hb concentration or in alveolar lung volume: and was accompanied primarily by an increased estimated Dm(co) and to a lesser extent by an expanded Vc. The interpretation and implications of these findings were limited by the low quantitative capability of Vc and Dm(co) estimates and by the cross-sectional nature of the study. Nevertheless, the higher than normal D(Lco) and Dm(co) in the non-native, long-term resident of 3,100 m was substantial, highly significant statistically, and consistent over a wide range of metabolic rates at rest and work. These data provide, then, a reasonable rationale upon which longitudinal experiments may be based to determine the true effects of chronic hypoxia on pulmonary gas exchange in man.

Acclimatization↗