A comparative analysis of the interpretations of lumbar spinal radiographs by chiropractors and medical doctors.

Ninety-nine anteroposterior and lateral lumbar radiographs taken of men, 18 to 55 years of age, were randomly selected from participants in a population survey of low-back pain. Thirty-one (31%) had never had low-back pain; 44 (44%) had or were having mild low-back pain; and 24 (24%) had or were having severe low-back pain. Three chiropractors assessed 56 radiographic variables, which included determinations of disc space height, vertebral malalignments and subluxations, spondylosis, postural disturbances, relationships among pelvis and spine and other congenital or acquired abnormalities. Interobserver reliability measurements showed that 6 of the 56 variables analyzed produced a high interobserver reliability. Sixteen additional variables showed a fair interobserver reliability. Comparison of the observations made by the chiropractors and a radiologist showed minimal agreement except for disc space height assessments at L3-4 and L4-5. Few of the radiographic variables discriminated between the current or prior history of low-back and leg complaints, although a few variables (most notably disc space narrowing) were statistically associated with back or leg complaints (P = .025). The conclusion was reached that spinal radiographs, whether analyzed by measurements, by a radiologist, or by chiropractors, have minimal value in determining the presence or absence of low-back complaints and, in particular, have no value in epidemiologic studies.

Respiratory symptoms and lung function in a sample of Vermont dairymen and industrial workers.

This study reviews the respiratory status of a sample of Vermont male dairy farmers, and a comparison group from industry, matched for age, sex and smoking. Survey instruments included a standardized questionnaire and simple pulmonary function tests. In general, past and present smokers had more respiratory symptoms than never-smokers; and farmers, in all smoking categories, reported symptoms with greater frequency than did their counterparts from industry. Forced vital capacity (FVC) tended to be lower among men with a history of smoking but, within each smoking category, dairymen and factory workers had very similar FVCs. Farmers who had never smoked or who were current cigarette users had lower FEV1/FVC (forced expiratory volume at one second/forced vital capacity) ratios than their controls from industry. Sixteen diarymen demonstrated precipitins to either Micropolyspora faeni (13) or Thermoactinomyces vulgaris, (3), but only one reported a constellation of symptoms compatible with farmer's lung disease. The estimated prevalence of antibodies to thermophilic actinomyces in this farm population was approximately 10 per cent. Although sample sizes were limited, dairymen from small farms tended to be older, have more respiratory symptoms, less satisfactory pulmonary function, and more serologic evidence of exposure to farmer's lung antigens than their counterparts from large farms.

Asbestos-induced epithelial changes in organ cultures of hamster trachea: inhibition by retinyl methyl ether.

The epithelium of the hamster trachea in organ culture undergoes hyperplasia and squamous metaplasia after exposure to the amphibole types of asbestos, crocidolite and amosite. These changes are inhibited when the synthetic vitamin A analog, retinyl methyl ether, is incorporated into the culture medium. These findings suggest a possible use for retinoids in the prevention and treatment of respiratory tract disease associated with environmental exposure to asbestos.