Publications

Activation of stellate cells is central to the process of hepatic fibrogenesis. Stellate cell activation can be influenced by many factors, including cytokines, oxidants, and alterations in the perisinusoidal extracellular matrix. These factors can be produced by resident liver cells (hepatocytes, Kupffer cells, or stellate cells themselves); however, infiltrating leukocytes may also play an important role. Because liver fibrosis often follows a prolonged period of hepatic inflammation, investigators have begun to study leukocytes as modulators of stellate cell activation. The following data summarize recent investigations in this area that focus on neutrophils as well as mononuclear cells.

BACKGROUND

Asthma has been found to be among the most common conditions in the working age population and is among the most common causes of work limitation, but we could find no longitudinal studies of employment among persons with this condition.

METHODS

A panel of 601 persons with a diagnosis of asthma from random samples of northern California pulmonologists and allergy-immunologists were interviewed as many as three times at 18-month intervals by a trained survey worker to report on the severity of disease, demographic characteristics, and the extent of their employment. Their employment was then compared to that of a matched sample from the U.S. Bureau of the Census Current Population Survey.

RESULTS

Ninety-two percent of the persons with asthma had worked at some point prior to study enrollment. Among persons with onset during adulthood, only 29% of those who were not employed at disease onset were working at study enrollment, compared to 68% among those who were employed. Among the 420 persons interviewed three times, 75, 81, and 75%, respectively, were employed as of the three interviews. Among these 420, 66% were continuously employed and 15% were continuously not employed. The principal determinants of continuity of employment were demographic and employment characteristics, not medical ones. The employment rate and hours of work per week and per year of the persons with asthma were similar to the matched sample.

CONCLUSIONS

Asthma has not substantially impeded the employment of the persons with asthma we studied, with the exception that those who were not employed at disease onset continued to have low employment rates.

BACKGROUND

In general practice settings, the proportion of adult asthma attributable to occupational factors is not known.

OBJECTIVE

The goal of this study was to estimate the proportion of adult asthma cases that can be attributed to occupational factors initiating new disease onset and exacerbating preexisting disease.

METHODS

We performed a cross-sectional analysis of interview data for 150 adults with asthma recruited from a random sample of family practice specialists. We ascertained the asthma and work histories of the subjects and estimated the proportion with likely work-initiated asthma and work-related asthma recrudescence.

RESULTS

Seventy-four subjects (49%) reported adult-onset asthma while employed; an additional 25 (17%) reported recrudescence of previously quiescent childhood-onset asthma during employment. Of those with new-onset asthma while employed, 15 (10% of the study group; 95% confidence interval, 5 to 15%) were employed in occupations at increased risk of occupational asthma initiation on the basis of an independent job scoring matrix. Of those with asthma recrudescence in adulthood, seven (5% of the study group; 95% confidence interval, 2 to 8%) were employed in occupations at increased risk of exposures aggravating asthma.

CONCLUSIONS

Among adults with asthma treated in general practice settings, > 1 in 10 patients has a work history strongly suggestive of a potential relationship between exposure and disease.