Publications

The integrin alpha9beta1 is one of the recently identified integrins whose expression is restricted to specialized tissues. Its exact function is still unknown. In the present study, we have analyzed the expression of the alpha9 subunit in human fetal and adult small intestinal and colonic epithelia as well as in intestinal cell lines by indirect immunofluorescence, immunoprecipitation, Western blot, and Northern blot. In intact tissues, the antigen was restricted to the basolateral domain of epithelial cells in intestinal crypts at the fetal stage and was absent in the adult. The alpha9beta1 integrin was also detected in the intestinal cell lines HIEC-6 and Caco-2/15. The presence of alpha9beta1 in HIEC-6 was found to be consistent with their proliferative crypt-like status. In Caco-2/15 cells, the integrin was present at high levels in proliferating cells but was downregulated when cells cease to grow and undertake their differentiation. EGF treatment, which is known to maintain Caco-2/15 cells in a proliferative state, resulted in higher levels of alpha9 as compared to control cells. Taken together, these observations suggest a relation between integrin alpha9beta1 expression and proliferation in human intestinal cells.

Cumene hydroperoxide-mediated (CuOOH-mediated) inactivation of cytochromes P450 (CYPs) results in destruction of their prosthetic heme to reactive fragments that irreversibly bind to the protein. We have attempted to characterize this process structurally, using purified, 14C-heme labeled, recombinant human liver P450 3A4 as the target of CuOOH-mediated inactivation, and a battery of protein characterization approaches [chemical (CNBr) and proteolytic (lysylendopeptidase-C) digestion, HPLC-peptide mapping, microEdman sequencing, and mass spectrometric analyses]. The heme-peptide adducts isolated after CNBr/lysylendopeptidase-C digestion of the CuOOH-inactivated P450 3A4 pertain to two distinct P450 3A4 active site domains. One of the peptides isolated corresponds to the proximal helix L/Cys-region peptide 429-450 domain and the others to the K-region (peptide 359-386 domain). Although the precise residue(s) targeted remain to be identified, we have narrowed down the region of attack to within a 17 amino acid peptide (429-445) stretch of the 55-amino acid proximal helix L/Cys domain. Furthermore, although the exact structures of the heme-modifying fragments and the nature of the adduction remain to be established conclusively, the incremental masses of approximately 302 and 314 Da detected by electrospray mass spectrometric analyses of the heme-modified peptides are consistent with a dipyrrolic heme fragment comprised of either pyrrole ring A-D or B-C, a known soluble product of peroxidative heme degradation, as a modifying species.

CONTEXT

The association between environmental tobacco smoke (ETS) exposure and respiratory symptoms has not been well established in adults.

OBJECTIVE

To study the respiratory health of bartenders before and after legislative prohibition of smoking in all bars and taverns by the state of California.

DESIGN

Cohort of bartenders interviewed before and after smoking prohibition.

SETTING AND PARTICIPANTS

Bartenders at a random sample of bars and taverns in San Francisco.

MAIN OUTCOME MEASURES

Interviews assessed respiratory symptoms, sensory irritation symptoms, ETS exposure, personal smoking, and recent upper respiratory tract infections. Spirometric assessment included forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) measurements.

RESULTS

Fifty-three of 67 eligible bartenders were interviewed. At baseline, all 53 bartenders reported workplace ETS exposure. After the smoking ban, self-reported ETS exposure at work declined from a median of 28 to 2 hours per week (P<.001). Thirty-nine bartenders (74%) initially reported respiratory symptoms. Of those symptomatic at baseline, 23 (59%) no longer had symptoms at follow-up (P<.001). Forty-one bartenders (77%) initially reported sensory irritation symptoms. At follow-up, 32 (78%) of these subjects had resolution of symptoms (P<.001). After prohibition of workplace smoking, we observed improvement in mean FVC (0.189 L; 95% confidence interval [CI], 0.082-0.296 L; 4.2% change) and, to a lesser extent, mean FEV1 (0.039 L; 95% CI, -0.030 to 0.107 L; 1.2% change). Complete cessation of workplace ETS exposure (compared with continued exposure) was associated with improved mean FVC (0.287 L; 95% CI, 0.088-0.486; 6.8% change) and mean FEV1 (0.142 L; 95% CI, 0.020-0.264 L; 4.5% change), after controlling for personal smoking and recent upper respiratory tract infections.

CONCLUSION

Establishment of smoke-free bars and taverns was associated with a rapid improvement of respiratory health.