Brief exposure to secondhand smoke reversibly impairs endothelial vasodilatory function.

INTRODUCTION: We sought to determine the effects of brief exposures to low concentrations of tobacco secondhand smoke (SHS) on arterial flow-mediated dilation (FMD, a nitric oxide-dependent measure of vascular endothelial function), in a controlled animal model never before exposed to smoke. In humans, SHS exposure for 30 min impairs FMD. It is important to gain a better understanding of the acute effects of exposure to SHS at low concentrations and for brief periods of time. METHODS: We measured changes in FMD in rats exposed to a range of real-world levels of SHS for durations of 30 min, 10 min, 1 min, and 4 breaths (roughly 15 s). RESULTS: We observed a dose-response relationship between SHS particle concentration over 30 min and post-exposure impairment of FMD, which was linear through the range typically encountered in smoky restaurants and then saturated at higher concentrations. One min of exposure to SHS at moderate concentrations was sufficient to impair FMD. CONCLUSIONS: Brief SHS exposure at real-world levels reversibly impairs FMD. Even 1 min of SHS exposure can cause reduction of endothelial function.

Evidence for an additional locus for split hand/foot malformation in chromosome region 8q21.11-q22.3.

We identified a family where five members had nonsyndromic ectrodactyly. There were three known instances of nonpenetrance. Although four individuals had unilateral cleft hand, one individual had more severe, bilateral and asymmetric absence of the digits. None had foot abnormalities. After exclusion of linkage of SHFM in this family to five known loci, a genome wide scan was performed with DNA from 5 affected and 15 unaffected members of this family. Suggestive evidence for linkage of ectrodactyly to 8q was obtained on the basis of a maximum LOD score of 2.54 at theta (max) = 0 with GAAT1A4. Critical recombinants place the ectrodactyly gene in this family in a 16 cM (21 Mb) interval between D8S1143 and D8S556. Mutational analysis of two candidate genes (FZD6, GDF6) did not identify any mutations in affected members of this family. Our data indicate further genetic heterogeneity for ectrodactyly and suggest the presence of an additional SHFM locus in chromosome region 8q21.11-q22.3.