Evaluation of the nasal response to histamine provocation with acoustic rhinometry.

The objectives of this study were to evaluate the reproducibility of the nasal response to histamine with the acoustic rhinometer and to compare the responses in normal and rhinitic subjects. Our study comprised 10 normal and 10 rhinitic subjects. Each subject had six sessions of provocation: three with histamine phosphate at a concentration of 4 mg/mL and three with saline phosphate provocation. Basal measurements of the nasal volumes were taken initially and then at 5-minute intervals for 90 minutes. All rhinometric measurements were made bilaterally and in triplicate. The variation between the triplicate measurements (2% +/- 0.1% [95% CI]) and the variation between the basal measurements (7.3% +/- 3.1% [95% CI]) were very low in both normal and rhinitic subjects. The comparison of the average congestive response of the normal subjects revealed that they responded steadily for at least 90 minutes to histamine and saline but that the response to histamine was significantly more important. There was also a low variability in the congestive response between the subjects. The comparison of the average congestive response of the rhinitic subjects revealed that their responses were more dynamic, not steady, compared with those of the normal subjects. The response was statistically significant only in the first few intervals. The comparison of the average congestive response to saline suggests that rhinitic subjects present a more important response than normal subjects. The comparison of the average congestive response to histamine between rhinitic and normal subjects was not statistically different but was different in the shape of the response pattern. Acoustic rhinometry is a highly reproducible method for measuring nasal volume in our provocation protocol. Histamine nasal provocation leads to a pattern of congestive response that is different in normal and rhinitic subjects. Histamine nasal provocation seems to be useful in addition to the study of nasal hyperreactivity and, as such, could permit differentiation between rhinitic and nonrhinitic subjects.

Comparative spin-label study of the dynamic structure of human hemoglobins A and F and the influence of the antibiotic, chloramphenicol.

Hemoglobin A (HbA) and hemoglobin F (HbF) dynamic structures have been studied using spin-label ESR spectra analysis technique, which permits quantitative separation of slow macromolecular rotation (described by rotational correlation time, tau c) and fast anisotropic nitroxide radical motion (described by the 'order parameter', S). The hardly restricted motion of the maleimide spin-label reflects the overall macromolecular rotation and small dynamic structure differences between HbA and HbF were observed (tau c is equal to 26 and 27 ns, respectively). On the other hand, the dynamic equilibrium of the iodoacetamide spin-label demonstrates significant differences between beta- and gamma-chain C-terminus flexibility. Thus, there are different states of alpha,beta and alpha,gamma intersubunit contacts which may be expected to determine the different O2 affinity of HbA and HbF. The antibiotic, chloramphenicol, strongly affects the O2 affinity and the Hill constant of HbF, and also provides detectable changes of gamma-subunit C-terminus flexibility (tau c changes from 20 ns to 27 ns after chloramphenicol treatment of HbF), while the HbA tetramer structure remains almost unaffected. The HbF domain structure rearrangements are accompanied by a decrease of the steric restriction of the spin-label motion (S changes from 0.75 to 0.72).