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At least 217 records · Page 12Linked to original sources
PubMed1989

Early markers of lung injury.

The goal of this study was to develop an early marker of lung injury that might change in response to exposure to a mobile source emission. Nitrogen dioxide (NO2)2 was chosen as an example of an atmospheric pollutant that is related to automobile emissions. Since reorganization of the connective tissue matrix of the lung occurs in response to injury, markers of connective tissue metabolism were selected as targets. Hydroxylysine became the marker of choice. It is an amino acid that is virtually exclusive to collagen, although it does occur in minimal amounts in other proteins. Furthermore, it is excreted in the urine, which makes it readily available for analysis using noninvasive techniques. Other markers evaluated as part of the study included angiotensin-converting enzyme as a marker of lung injury, desmosine as a marker of elastin degradation, and hydroxyproline as another marker of collagen metabolism. Male Fischer-344 rats were exposed in whole-body chambers to controlled concentrations of NO2 for various doses and periods of time. The concentrations of NO2 ranged from 0.5 to 30 parts per million (ppm); the rats were exposed for six hours per day for periods of two days to four weeks. Urine and bronchoalveolar lavage samples were collected and analyzed for the appropriate marker. In addition, pulmonary function studies and histologic examinations of the lungs were completed at selected time points. Urinary hydroxylysine concentration increased as a function of NO2 concentration during six-hour-per-day exposures for two days. This short-term exposure required relatively high doses to achieve significant changes in the hydroxylysine output. During one-week exposures to either 25 or 30 ppm NO2, there was an increase in urinary hydroxylysine associated with changes in lavage concentrations of angiotensin-converting enzyme and hydroxylysine. The lungs of these animals demonstrated histologic changes typical of oxidant injury. Four-week exposure protocols using 0.5 and 1 ppm NO2 were most interesting in terms of the sensitivity of the marker. There was minimal damage revealed by the histology and function studies, yet there were significant increases in the excretion of hydroxylysine. It appears that hydroxylysine can be indicative of exposure when other parameters are normal. It will require long-term follow-up of exposed rats to determine whether or not the change in marker concentration is predictive of damage. Hydroxylysine may be an excellent marker of exposure to oxidants in the human population. Controlled studies to establish base-line values are needed, followed by carefully controlled studies in individuals with connective tissue abnormalities of the lung.

Animals↗
PubMed1984

Collagen specific amino acids in skin in localized scleroderma.

Hydroxyproline, hydroxylysine and proline were determined on skin from 18 patients with localized scleroderma (10 with localized morphoea plaque and 8 with generalized morphoea). Three skin biopsies (4mm punch) were obtained from each patient: One from the center of a sclerotic plaque, one from the perilesional area, and one (control) from unaffected skin of the same region. Clinically, the sclerosis was more pronounced (p less than 0.01) in localized morphoea plaque as compared to generalized morphoea. Patients with localized morphoea plaque had an increased concentration of hydroxylysine (p less than 0.01) and an increased ratio of hydroxylysine to hydroxyproline (p less than 0.01) in the plaques. Hydroxylysine concentration was not changed in patients with generalized morphoea. In the entire material, increased hydroxylysine concentration were related to shorter age of the plaques (p less than 0.05) and to advanced degree of sclerosis (p less than 0.05). The hydroxylysine and hydroxyproline content per mm2 skin surface, and the weight of the dried defatted biopsy cores were increased in sclerotic plaques (p less than 0.01) in localized as well as generalized morphoea. There were no changes in the hydroxyproline and proline concentrations in any of the groups. Specimens from perilesional area showed intermediate changes. The results were compared with selected cases of lichen sclerosis et atrophicus and atrophic skin diseases. The increase in hydroxylysine concentration and ratio to hydroxyproline indicate that patients with localized morphoea plaque contain an increased proportion of newly synthesized collagen in the fibrotic plaque.

Adolescent↗
PubMed2005

Kinetics of collagen crosslinking in adult bovine articular cartilage.

OBJECTIVE: Determine the kinetics of collagen crosslinking in adult bovine articular cartilage explants using radiolabel pulse-chase studies. METHODS: Explant cultures of adult bovine articular cartilage were radiolabeled with [14C]lysine in medium including fetal bovine serum and ascorbate, and then maintained for chase periods up to 28 days. In some samples, beta-aminopropionitrile (BAPN) was included during chase to inhibit lysyl oxidase-mediated collagen crosslinking. Tissue was hydrolyzed and analyzed for [14C]metabolites in the forms of lysine, hydroxylysine, dehydrodihydroxylysinonorleucine (DeltaDHLNL), and hydroxylysyl pyridinoline (HP). RESULTS: Explant cultures of adult bovine articular cartilage metabolized lysine into hydroxylysine and the collagen crosslinks, DeltaDHLNL and HP. During chase, [14C]hydroxylysine maintained steady-state levels, [14C]DHLNL rose to a plateau, and [14C]HP increased gradually. Addition of BAPN inhibited formation of [14C]DHLNL. Analysis of raw data and that normalized to [14C]hydroxylysine gave characteristic time constants for formation of DeltaDHLNL and HP crosslinks of 1-2 and 7-30 days, respectively. The distribution of [14C]lysine metabolites in collagen crosslinks was described by peak values in [14C]DHLNL/[14C]hydroxylysine of 0.047-0.064 and in [14C]HP/[14C]hydroxylysine of 0.03. CONCLUSION: Collagen crosslinks form in cartilage explants in vitro according to the classical lysyl oxidase-mediated pathway.

Amino Acids↗
PubMed1974

Biochemical properties of human glomerular basement membrane in normal and diabetic kidneys.

To determine the presence of any significant structural abnormalities in the glomerular basement membrane (GBM) of diabetic individuals, GBM from normal and diabetic human kidneys were isolated and analyzed chemically and structurally. The amino acid composition of the normal GBM revealed the presence of significant amounts of hydroxyproline, hydroxylysine, glycine, and carbohydrate suggesting the presence of a collagen-like protein. There was no significant increase in the amount of hydroxylysine, hydroxyproline, or in the hydroxylysine-linked glycoside glucosyl-galactose in the diabetic kidneys. There was, however, a significant decrease in the cystine and sialic acid content of GBM from diabetic kidneys. It was further shown that the alpha-chains isolated from the collagens of normal and diabetic basement membranes had similar amino acid and carbohydrate compositions. The hydroxylysine, hydroxyproline, glycine, and hexose contents were higher by 82, 56, 74, and 94%, respectively in the alpha-chains compared with the intact basement membranes from both the normal and diabetic kidneys. The results indicate that the slight increases in hydroxylysine and hexose content observed occasionally in diabetic GBM preparations are of no statistical significance and cannot be attributed to increases in the activities of enzymes which hydroxylate lysine or glycosylate hydroxylysine, respectively.

Adult↗
PubMed2000

A rapid and simple method for quantitation of urinary hydroxylysyl glycosides, indicators of collagen turnover, using liquid chromatography/tandem mass spectrometry.

Some glycosides of hydroxylysine, viz., alpha-1, 2-glucosylgalactosyl-O-hydroxylysine and beta-1-galactosyl-O-hydroxylysine, appear to be good indicators of collagen turnover. A simple liquid chromatography/tandem mass spectrometry (LC/MS/MS) method is proposed for measuring these analytes in urine, with no sample preparation except for a dilution step. Quantitation is performed using external calibration with no internal standard. A preliminary survey indicates good intra- and inter-day reproducibility (better than 5 and 8%, respectively). With the present method, the estimated limits of detection (S/N > 3) in urine are 0.8 and 0.5 microM/L for beta-1-galactosyl-O-hydroxylysine and alpha-1,2-glucosylgalactosyl-O-hydroxylysine, respectively. The method is proposed as a robust tool for a large-scale research investigation on collagen turnover.

Chromatography, Liquid↗
PubMed1996

Collagen type I of rat cortical and trabecular bone differs in the extent of posttranslational modifications.

This study sought to evaluate whether the architecture of the matrix of cortical and trabecular bone is exactly the same. For this purpose we analyzed the extent of some posttranslational modifications of type I collagen, which is the major component of bone matrix. Ten female and 10 male 100-day-old rats were sacrificed and the content of hydroxylysine, glycosylated hydroxylysine, and pyridinium cross-links of collagen from cortical and trabecular bone was determined. The amount of each compound was expressed as a molar ratio with hydroxyproline. The collagen posttranslational modification pattern appears to be the same in both sexes but with a higher extent of differences in females compared with males. Comparing cortical and trabecular bone, the former contains a higher amount of hydroxylysine residues whereas in the latter, glycosylation of hydroxylysine is higher and pyridinium cross-link concentration is lower. Moreover, an inverse linear relationship between glycosylated hydroxylysine and pyridinium cross-links concentration was established, both for female (r = -0.455, P = 0.04) and male rats (r = -0.426; P = 0.06). This paper discusses what these findings may mean in functional terms.

Adrenal Cortex Hormones↗