Correlation of collagen linked fluorescence and tendon breaking time.

We review in this paper some reported data on age-dependent modification of proteins pointing out the relationship between the increase of nonenzymatic glycation in abdominal skin collagen of Wistar rats, evaluated by fluorescence intensity, and tendon breaking time, used as a parameter of collagen stiffness. Fluorescence intensity data linearly correlate with the breaking times of collagen fibers from Wistar rats reported from different sources, according to the hypothesis of a common etiological mechanism. It is possible to suppose that posttranslational modifications of proteins play a role in the tissue aging and their level in collagen may be used as a parameter for quantitation

Age-related increase of collagen fluorescence in human subcutaneous tissue

Nonenzymatic glycation produces compounds with characteristic fluorescence in long-lived proteins. We recently described the influence of age in rat collagen-linked fluorescence. To examine the effect of age in humans, we studied the subcutaneous collagen-linked fluorescence in samples from 26 subjects of both sexes (age range, 42 to 78 years) who were undergoing vascular surgery. Intensity of fluorescence at 385 nm (upon excitation at 335 nm) and 440 nm (upon excitation at 370 nm) increased exponentially with age (r = .827, y = 114 + e(0.038x), P < .001; and r = .905, y = 36 + e(0.039x), P < 0.001, respectively). The two sets of data exhibited a high degree of correlation (r = .980, P < .001, n = 26). Age-adjusted fluorescence data did not correlate with sex, body weight, or type of vascular pathology. The collagen fluorescence accumulation rate was 3.7% per year, and the characteristic time (CT) was 26 to 27 years. We conclude that the fluorescence measurement is a reliable methodology that can be used as a marker for biological age until new, more-specific tools are available