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Background: Systematic aerobe training has positive effects on the compliance of dedicated arterial walls. The adaptations of the arterial structure and function are associated with the blood flow-induced changes of the wall shear stress which induced vascular remodelling via nitric oxide delivered from the endothelial cell. In order to assess functional changes of the common carotid artery over time in these processes, a precise measurement technique is necessary. Before this study, a reliable, precise, and quick method to perform this work is not present.Methods: We propose a fully automated algorithm to analyze the cross-sectional area of the carotid artery in MR image sequences. It contains two phases: (1) position detection of the carotid artery, (2) accurate boundary identification of the carotid artery. In the first phase, we use intensity, area size and shape as features to discriminate the carotid artery from other tissues and vessels. In the second phase, the directional gradient, Hough transform, and circle model guided dynamic programming are used to identify the boundary accurately.Results: We test the system stability using contrast degraded images (contrast resolutions range from 50% to 90%). The unsigned error ranges from 2.86% ± 2.24% to 3.03% ± 2.40%. The test of noise degraded images (SNRs range from 16 to 20 dB) shows the unsigned error ranging from 2.63% ± 2.06% to 3.12% ± 2.11%. The test of raw images has an unsigned error 2.56% ± 2.10% compared to the manual tracings.Conclusions: We have proposed an automated system which is able to detect carotid artery cross sectional boundary in MRI sequences during heart cycles. The accuracy reaches 2.56% ± 2.10% compared to the manual tracings. The system is stable, reliable and results are reproducible. [ABSTRACT FROM AUTHOR]

The method of scattering was applied to determine the effect of chemical modification on the conformation of the basic pancreatic trypsin inhibitor in aqueous solution. Cleavage of one of the three disulfide bonds yields no spectral changes except, of course, the manifestation of the reduction, i.e. a lower intensity of the disulfide band and the appearance of a line due to the newly formed sulfhydrylgroups. S-alkylation, however, produces several changes in the spectra as compared to the native inhibitor. In the case of the carboxymethylderivative the amide III band, shifted to lower frequency, is particularly significant. This observation suggests that the inactivity towards trypsin of the reduced carboxymethyl inhibitor is the result of structural changes near the reactive center of the molecule. [ABSTRACT FROM AUTHOR]

Characterizes the quaternary state of the unligated hemoglobin via laser Raman scattering. Band frequency of absorption spectra; Shape of the Soret band; Influence of quaternary structure on excited electronic states; Electronic properties of the heme in unligated hemoglobin.