Summary: Left ventricular internal dimensions, septal and posterior wall thickness, aortic root diameter, and left atrial dimensions, were independently measured by two experienced interpreters on 50 consecutive routinely performed M-mode echocardiograms. The purpose of this work was to evaluate the reproducibility of these measurements and to assess if a different "diagnostic effect" could be provided by the two readers. The extent of interobserver variability was calculated and expressed as a percent of the mean. No significant interobserver variability was found for all the measured echocardiographic parameters and the two interpreters gave rise to the same "diagnostic effects." Therefore, the authors suggest following well stated guidelines to provide uniformity in the process of determining the boundaries of the structures to be measured and adjusting the actual measurements by multiplying by a conversion factor (representing the ratio between the number of 1 cm markers and the distance in centimeters between the first and the last marker), as opposed to interpolating between the marks on the recording paper.
Pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) are two cross-links of collagen molecules, that are present in the extracellular matrix and released during its degradation. Pyr is present in bone and cartilage, but not in significant amounts in other connective tissues and D-Pyr appears to be specific for bone tissue. Therefore, the urinary excretion of Pyr and D-Pyr might be a sensitive marker of bone matrix degradation. For the determination of urinary Pyr and D-Pyr two methods are available: a chromatographic method (HPLC) by which it is possible to measure separately Pyr and D-Pyr, and a new immunoassay which measures total free and low molecular weight pyridinoline released in the urine. We compared the results obtained by HPLC analysis of 205 urinary samples from normal subjects and patients affected by various bone disorders with those obtained by the immunoassay. The overall correlation coefficient between the results obtained by the two methods was 0.34. When calculated in a range of pyridinoline concentrations from 0 to 30, 30 to 60, and over 60 pmol/mumol creatinine the correlation coefficient was respectively -0.094, 0.38, and 0.12. The two methods yielded variable profiles in the detection of circadian rhythms and these differences did not segregate with normal or pathological conditions. We conclude that the immunoassay proposed for the determination of urinary collagen cross-links is not immediately applicable to clinical use. The improvement of the antibody specificity will probably contribute to replace the HPLC method with the immunoassay.
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