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Acid soluble type I collagen was prepared from fetal and adult bovine tendon and skin and from adult bovine cornea. The degree of hydroxy lysine glycosylation and the hydroxy lysine di-to monoglycoside ratio as well as the “in vivo” fibril diameters, were shown to be tissue and age-dependent. Fibrils of type I collagen were reconstituted “in vitro” monitoring at 313 nm. The fibrils obtained were examined by electron microscopy. It was shown that the “in vitro” lateral growth of collagen fibrils leads to the formation of fibrils with maximum diameters which may be correlated to those of the corresponding native fibrils. Moreover it is suggested that one of the factors controlling the lateral growth of collagen may be at the level of hydroxy lysine glycosylation.

Diurnal variations in the excretion of bone resorption markers were assessed in order to identify the type of urine collection which provides the most information on bone resorption rate and its relation to measuring bone dynamics in a postmenopausal population. Sixty women, ages 43–67 and without disease or treatment known to affect bone mineral density, were divided into two groups on the basis of femoral mineral density T‐score: 1.5 (Group II). Bone formation was assessed by measuring bone alkaline phosphatase activity and osteocalcin concentration, bone resorption by urinary hydroxyproline, pyridinoline and deoxypiridinoline, N‐telopeptide, galactosyl hydroxylysine, and CrossLaps. To identify the more appropriate collection times, urine samples were collected from 7 am to 3 pm; from 3 pm to 11 pm; from 11 pm to 7 am. Twenty‐four hour urine collection and first morning void urine samples were also measured. The findings suggest that nocturnal collection and first morning void samples provide the most reliable data on the rate of bone degradation, possibly showing bone loss not only in osteopenic patients but also in women with a low T‐score. Nocturnal and first morning samples should therefore be recommended in order to standardize sample collection, as they enable an accurate assessment of bone resorption markers and improved comparability to results from different studies, as well as a less cumbersome collection modality. J. Clin. Lab. Anal. 12:145–149, 1998. © 1998 Wiley‐Liss, Inc.