Urinary Hydroxylysine Glycosides Research Articles

Improved HPLC determination of urinary hydroxylysine glycosides to study turnover rate of bone in humans and rats

Improved HPLC determination of urinary hydroxylysine glycosides to study turnover rate of bone in humans and rats

Urinary hydroxylysine glycosides: Solid phase extraction and reversed phase chromatographic measurement

A method is described for measurement of urinary hydroxylysine glycosides (galactosyl-hydroxylysine, or GHYL, and glucosyl-galactosyl-hydroxylysine, or GGHYL) by reversed phase chromatography after purification of the sample by solid phase extraction. Urinary levels of hydroxylysine glycosides has been correlated with collagen catabolism, and the urinary GGHYL: GHYL ratio is indicative of the metabolism of connective tissue. The GGHYL:GHYL ratio might, therefore, be a promising indicator of bone mass loss. The method described is analytically reliable and enables the measurement of a possible marker for diagnosis and follow-up of osteoporosis.

Biochemical markers of bone turnover.

The noninvasive assessment of bone turnover has received increasing attention over the past few years because of the need for sensitive markers in the clinical investigation of osteoporosis. Markers of bone formation include the serum measurement of total and bone-specific alkaline phosphatase, osteocalcin, and type I collagen extension peptides. Assessment of bone resorption can be achieved with measurement of fasting urinary calcium and hydroxyproline, urinary hydroxylysine glycosides, urinary excretion of the pyridinium cross-links (pyridinoline and deoxypyridinoline), and plasma tartrate-resistant acid phosphatase activity. Several studies performed in a variety of metabolic bone diseases have shown these markers to be of unequal sensitivity and specificity. In addition, some of them are not fully characterized. For assessment of the level of bone turnover in women with vertebral osteoporosis, serum osteocalcin and urinary pyridinoline appear to be the most sensitive markers so far. Programs combining bone mass measurement and assessment of bone turnover by several markers in women at the time of menopause are being developed in an attempt to improve the assessment of the risk for osteoporosis. Efforts are being made to develop more convenient assays and to identify other markers of bone turnover. A battery of various specific markers is likely to improve the assessment of the complex and subtle abnormalities of bone metabolism that characterize metabolic bone diseases, especially the various aspects of osteoporosis.

High-performance liquid chromatographic method for measuring hydroxylysine glycosides and their ratio in urine as a possible marker of human bone collagen breakdown

Glucosyl-galactosyl-hydroxylysine (GGHYL) and galactosyl-hydroxylysine (GHYL) are constituents of collagen protein. The ratio of the two hydroxylysine glycosides varies with the collagen type and, moreover, for a given collagen type, it also varies according to the connective tissue. For example, in type I collagen (the most abundant in the body), the GGHYL GHYL ratio tends to be greater in soft connective tissues and lower in bone. The hydroxylysine glycosides are not recycled during collagen turnover and are excreted in the urine. Therefore, the urinary GGHYL GHYL ratio, which reflects the proportion of the two metabolites in the various collagens, may indicate the type of connective tissue affected by pathological turnover, and may thus be a promising marker of bone metabolism. In this paper a method is described for the measurement of urinary hydroxylysine glycosides by reversed-phase liquid chromatography after purification of the sample by solid-phase extraction. The method presented is analytically reliable and suitable for routine use in a clinical laboratory.

Study on Dietary Effect of Protein Intake on Urinary Excretion Levels of Hydroxylysine Glycosides and Their Diurnal and Day to Day Variations.

The amount of urinary hydroxylysine glycosides (Hyl-Gs) is an index of collagen metabolism. The diurnal and day to day variations in the urinary excretion levels of Hyl-Gs and the effects of diet, especially the intake of a large amount of protein on them, were investigated. The diurnal variation in the urinary excretion levels of Hyl-Gs was within the range of healthy controls ; on the other hand, the day to day variation in the urinary excretion levels of Hyl-Gs was not observed. Although the urinary excretion of Hyl-Gs follows the same physiological variations as urinary hydroxyproline, it was not influenced by the dietary protein intake. The contents of Hyl-Gs (μmol/g creatinine) in the first micturition urine after arising and those in the 24-h urine were found to be highly correlated, so it is suggested that the first micturition urine after arising, instead of the 24-h urine, is useful to evaluate the diurnal collagen metabolism.

Pre-column derivatization and its optimum conditions for quantitative determination of urinary hydroxylysine glycosides by high-performance liquid chromatography.

A method has been developed for rapid analysis of the urinary hydroxylysine glycosides [glucosyl-galactosyl-hydroxylysine (GGH) and galactosyl-hydroxylysine (GH)] as collagen metabolites. The glycosides were fluorometrically derivatized with 5-dimethylaminonaphthalene-1-sulfonyl chloride, and then subjected to reversed-phase high-performance liquid chromatography using a gradient system. Suitable standard hydroxylysine glycosides which were not diastereoisomers were prepared from human urine. Urinary GGH and GH were analyzed within 1 h, including column washing. This method was applied to the urine samples of 68 healthy persons of different ages.

Alteration of collagen metabolism in hereditary nephritis.

Summary: Hereditary nephritis (HN) is a progressive renal disease not uncommonly seen in children. Asymptomatic hematuria is an early and consistent finding with or without proteinuria. Distinctive abnormalities frequently associated with this condition involve basement membranes primarily (glomerular basement membrane, lens capsule, and possibly, tectorial membrane of the organ of Cord). These basement membranes contain collagen with similar biochemical composition suggesting that this association may be pathogenetically related. On the basis of this observation, we studied collagen metabolism in patients with HN by utilizing urinary hydroxylysine glycosides (hyl glyc) as an index of collagen metabolism. The hyl glyc hydroxylysine galactose glucose and hydroxylysine galactose are basic units in basement membrane as well as a large number of other collagen. We studied 25 normal children, seven patients with HN, and six HN siblings with hematuria. The mean excretion of total hyl glyc are 64 ± 5.5, 93 ± 14, and 123 ± 15.6 umoles/g creatinine, respectively. The difference in the mean excretion level of total hyl glyc between patients with HN and normal controls is statistically different (P 0.005), but was comparable to the HN patients. Two of 16 additional patients studied had the Nail Patella syndrome and showed increased urinary hyl glyc. The elevated urinary hyl glyc in HN patients and their siblings strongly suggests an altered rate of collagen degradation during the natural course of the disease. The origin of collagen is presently unknown because no data exists describing the biochemical composition of basement membrane collagen in HN. To elucidate further the pathogenesis of this important disease, studies should investigate the biosynthesis and metabolism of basement membrane collagen of involved structures. Speculation: Collagen metabolism in HN suspect patients will raise the index of suspicion if found to be altered. This observation may provide increased understanding of the pathogenesis of this disorder.

A USEFUL BIOCHEMICAL MARKER IN THE IDENTIFICATION OF HEREDITARY NEPHRITIS: HYDROXYLYSINE GLYCOSIDES (OHLG's)

Collagen metabolism was studied in 9 children with hereditary nephritis and 10 family members with microscopic hematuria. The diagnosis was confirmed in all 9 children by percutaneous renal biopsy. No previous studies exist defining the collagen turnover via the utilization of the urinary OHLG's, hydroxylysylgalactosyl-glucose (HGG) and hydroxylysyl-galactose (HG), in hereditary nephritis. Mean urinary OHLG's values in the biopsy group was 113 uM/g creatinine as compared to 15 control children of 74 uM/g creatinine. The mean urinary values of 128 u M/g creatinine for the siblings were comparable to the nephritis group. Two additional patients with the Nail-Patella Syndrome also demonstrated increased urinary excretion of OHLG's. The significantly increased urinary excretion of these metabolites, HGG and HG, support the thesis of an altered collagen disorder. This study suggests that urinary hydroxylysine glycosides may be used as a useful marker in the recognition of the early stage of hereditary nephritis.

Collagen breakdown and nitrogen dioxide inhalation.

Measurements of urinary hydroxylysine glycosides indicate that considerable collagen degradation occurred during the reentry into the earth's atmosphere of the American astronauts of the Apollo-Soyuz mission. Since the crew accidentally inhaled nitrogen dioxide, a recognized pulmonary irritant, and showed clinical and roentgenographic signs of diffuse chemical pneumonitis, it is likely that collagen degradation occurred in the pulmonary parenchyma.