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PubMed1984

Formation of long-lived hydroxyl free radical adducts of proline and hydroxyproline in a Fenton reaction.

Proline and hydroxyproline when exposed to the hydroxyl free radical generating system of ADP-Fe(II)-H2O2 yielded long-lived free radicals. An analysis of the electron paramagnetic resonance spectra of the long-lived hydroxyl free radical adducts of proline and hydroxyproline is consistent with a free electron on a nitroxyl group interacting with the nitrogen atom as well as with three separate protons. In the case of proline, nitroxide formation was observed under the influence of tert-butyl-hydroperoxide, giving a similar EPR spectrum (Lin, J.S., Tom, T.C. and Olcott, H.S. (1974) J. Agr. Food Chem. 22, 526-528); however, the hydroxyl free radical adduct of hydroxyproline has not been described yet. In the case of the proline nitroxide radical, two of the three protons involved interact with the free electron equivalently. The coupling constants for the hydroxyl free radical adduct of proline are AN = 1.58 mT, AH1 beta = AH2 beta = 2.13 mT, AH3 beta = 1.77 mT and for hydroxyproline are AN = 1.54 mT, AH1 beta = 2.56 mT, AH2 beta = 2.03 and AH3 beta = 1.51. The data are consistent with the amine nitrogen of proline and hydroxyproline being oxidized to a nitroxyl group and the free electron of the nitroxyl interacting with the beta-protons of these amino acid hydroxyl free radical adducts.

Adenosine Diphosphate↗
PubMed1980

The excretion of hydroxyproline in urine during the healing of fractures and after sagittal splitting of the mandible.

Total excretion of hydroxyproline was measured in patients with fractures of long bones and in patients undergoing sagittal splitting of the mandible. In both patient groups excretion of hydroxyproline was twice that of normal healthy subjects. The amount of excreted hydroxyproline in patients with fractures was related to the site of the fracture, to the age of the patient, and the form of therapy. The excretion of hydroxyproline was found to be variable after wire adaptation of mandiblular osteotomy segments and after sagittal splitting without wire adaptation. Quantitative analysis of the excretion of hydroxyproline in urine does not therefore permit conclusions about the bone healing process.

Adolescent↗
PubMed2005

Shape of 4S- and 4R-hydroxyproline in gas phase.

The alpha-amino acids 4(S)-hydroxyproline and 4(R)-hydroxyproline have been studied under isolation conditions in gas phase using laser-ablation molecular-beam Fourier transform microwave spectroscopy. Two conformers of each molecule have been detected in the jet-cooled rotational spectrum. The most stable conformer in both molecules exhibits an intramolecular N...H-O hydrogen bond (configuration 1) between the hydrogen atom of the carboxylic group and the nitrogen atom. The second conformer is characterized by an intramolecular N-H...O=C hydrogen bond (configuration 2). The conformers of 4(R)-hydroxyproline adopt a C(gamma)-exo puckering, while those of 4(S)-hydroxyproline present a C(gamma)-endo ring conformation. These ring conformations, which show the same propensity observed in collagen-like peptides, are stabilized by additional intramolecular hydrogen bonds involving the 4-hydroxyl group, with the exception of the most stable form of 4(S)-hydroxyproline for which a n-pi interaction between the oxygen atom of the 4-hydroxyl group and the carboxyl group carbon seems to be established. A gauche effect could be also contributing to stabilize the observed conformers.

Fourier Analysis↗
PubMed1978

Three-centre study on urinary hydroxyproline excretion in cancer of the breast.

A study instigated by the British Breast Group and involving 3 centres (Edinburgh, Glasgow and Liverpool) was carried out to compare 3 methods for the estimation of urinary hydroxyproline. No significant difference between the first and the second 24 h urine collection was found for each measure of urinary hydroxyproline, within laboratories and within patient groups. Reliable hydroxyproline studies can, therefore, be performed on one 24 h urine collection. The Grant and Ellis/Goldberg methods gave comparable results and the excretion of hydroxyproline in the urine measured by either of these 2 methods could be used to distinguish cases of breast cancer with osseous involvement (as demonstrated by X-rays) from those without. The Hypronosticon Kit method was found to be unreliable as it has 29.4% false negatives in breast-cancer patients with X-ray demonstrable metastases. The incidence of elevated urinary hydroxyproline excretion in breast-cancer patients with negative X-rays was 11/14 (25%), 5/34 (15%) and 8/43 (19%) for the Ellis/Goldberg, Hypronosticon and Grant methods respectively. No conclusion can be drawn regarding the outcome of this group of patients because of the short period of follow-up.

Adult↗
PubMed1979

Total urinary and free serum hydroxyproline in metastatic bone disease.

The present study examines the possibility of correlation between free serum and urinary total hydroxyproline and whether this correlation can be applied to clinical conditions. The correlation between the two indices was 0.80 (P less than 0.001) in 18 patients, mostly suffering from malignant disease. On comparing the same measurements in 37 patients, all with known metastatic bone disease, we found 29/37 normal results for free serum hydroxyproline, whereas only 2/37 values of urinary total hydroxyproline were normal. The authors therefore conclude that urinary total hydroxyproline, measured as the ratio hydroxyproline/creatinine in a fresh specimen of early-morning urine, is the best index of collagen breakdown in metastatic bone disease and preferable to measurement of free serum hydroxyproline.

Adult↗
PubMed1977

Urinary hydroxyproline, creatinine and urea excretion during the growth of five siblings.

Urinary excretions of hydroxyproline, creatine and urea in 24 h specimens from 5 siblings have been determined monthly from 1971 to 1976 together with the measurements of body height and body weight. Changes with age in the urinary levels of these substances are in good agreement with those from cross-sectional studies in various age groups of children. Wide fluctuations of excretion levels occurred. The creatinine coefficients did not remain constant even over short periods. Menarche was observed shortly after the peak of hydroxyproline excretion at puberty. The hydroxyproline excretion pattern is similar to that of hydroxyproline index proposed by Whitehead, and it is quite different from that of hydroxyproline ratio.

Adolescent↗
PubMed1979

Interrelationships in rats among dietary vitamin B6, glycine and hydroxyproline. Effects of oxalate, glyoxylate, glycolate, and glycine on liver enzymes.

Urinary endogenous oxalate was increased by feeding vitamin B6-deficient or control rats with 5.2% hydroxyproline, or 3% glycine plus 5.2% hydroxyproline. The activities of liver lactic dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD) , malic enzyme (ME), and ATP citrate lyase were decreased in vitamin B6-DEFICIENT RATS, AND THEIR LIVEr G6PD was further decreased by the addition of glycine and hydroxyproline to their diets. Supplementing control diets with the two amino acids decreased the activities of rat liver LDH, G6PD, and ATP citrate lyase. The effects of glycine and hydroxyproline feeding on the enzymes studied did not appear related to alterations in insulin availability. Since in vitamin B6-deficient rats, there are increases in urinary levels of oxalic and glycolic acids, and glycine, and increases in tissue levels of glyoxylic acid and glycine, the effects of these metabolites on the activities of the above mentioned enzymes were measured. Oxalic acid inhibited the activities of LDH, G6PD, and ME. Glyoxylic acid inhibited LDH and ME, but not G6PD. Glycolic acid inhibited G6PD and ME, but not LDH. ATP citrate lyase was not affected by these substances. Glycine had no effect on the enzymes studied. Diets which increased oxalate excretion generally reduced or did not alter liver and kidney levels of oxalate, glycolate, and glyoxylate. However, the feeding of glycine and hydroxyproline increased kidney oxalate, and liver and kidney glyoxylate in vitamin B6-deficient rats.

ATP Citrate (pro-S)-Lyase↗
PubMed1985

Effect of ascorbic acid nutriture on protein-bound hydroxyproline in guinea pig plasma.

This paper provides indirect evidence that ascorbate nutriture affects plasma concentrations of complement component C1q in the guinea pig. C1q is a protein with a hydroxyproline-rich region similar in structure to collagen. It is essential for complement-mediated lysis of pathogens and may also facilitate phagocytic activity of macrophages and neutrophils. Since C1q is the only hydroxyproline-containing protein in the euglobulin fraction of plasma, it can be quantified indirectly by precipitating this fraction, hydrolyzing it and estimating hydroxyproline colorimetrically. We investigated the effect of ascorbate nutriture on protein-bound hydroxyproline (PBH) in the euglobulin fraction of plasma of young male guinea pigs. The animals had been depleted of ascorbate for 3 wk to produce scurvy and then repleted (6 wk) as follows: 0.5, 2.0 and 10.0 mg ascorbate/100 g body weight per d or 10 g ascorbate per liter of drinking water. PBH values were significantly correlated (P less than 0.001) with dietary ascorbate (+ 0.74) and with liver ascorbate (+ 0.75). Plasma PBH was significantly higher (P less than 0.01, Scheffé's test) in guinea pigs fed ample ascorbate (10.0 mg/100 g body weight per day) or tissue-saturating levels (10 g/L of drinking water) than in those fed adequate (2.0 mg/100 g body weight) or suboptimal (0.5 mg/100 g body weight) levels. These data are consistent with the known biochemical role of ascorbic acid in hydroxyproline biosynthesis and suggest a possible link between ascorbate and the immune response via C1q.

Animals↗
PubMed2003

Control of oxalate formation from L-hydroxyproline in liver mitochondria.

Serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT) is largely located in mitochondria in carnivores, whereas it is entirely found within peroxisomes in herbivores and humans. In rat liver, SPT/AGT is found in both of these organelles, and only the mitochondrial enzyme is markedly induced by glucagon. Although SPT/AGT is a bifunctional enzyme involved in the metabolism of both L-serine and glyoxylate, its contribution to L-serine metabolism is independent of mitochondrial or peroxisomal localization (Xue HH et al., J Biol Chem 274: 16028-16033, 1999). Therefore, the species-specific and food habit-dependent organelle distribution might be required for proper metabolism of glyoxylate at the subcellular site of its formation. Glyoxylate formation from glycolate and that from L-hydroxyproline have been shown to occur in peroxisomes and mitochondria, respectively. The present study found that urinary excretion of oxalate was markedly increased when a large dose of L-hydroxyproline or glycolate was administered to rats. Oxalate formation from L-hydroxyproline but not that from glycolate was significantly reduced when mitochondrial SPT/AGT had been induced by glucagon. The hydroxyproline content of collagen is 10 to 13%, and collagen accounts for about 30% of total animal protein; therefore, these results suggest that an important role of mitochondrial SPT/AGT in carnivores is to convert L-hydroxyproline-derived glyoxylate into glycine in situ, preventing undesirable overflow into the production of oxalate.

Animals↗
PubMed2005

Hydroxyproline content of needle biopsies as an objective measure of liver fibrosis: Emphasis on sampling variability.

BACKGROUND: Needle liver biopsy is essential for the diagnosis of liver fibrosis and cirrhosis. However, sampling variability has been reported by semiquantitative methods. The aim of the present study was to investigate quantitatively the sampling variability of needle liver biopsy on the assessment of liver fibrosis/cirrhosis. METHODS: Liver samples of 12 patients undergoing autopsy, liver transplantation, or liver tumor resection were investigated. Nine to 10 liver biopsies at least 5 mm apart were taken from each of 12 removed human livers using Trucut needles. Hydroxyproline level of each liver core was determined. Sections >1 cm(2) and stained by Sirius red were used for the reference staging of liver fibrosis in each patient according to the METAVIR scoring system. RESULTS: Hydroxyproline levels for the three groups, F0-1, F2-3, and F4, were significantly elevated as the fibrosis score increased. There was a wide range of hydroxyproline contents for the 9-10 biopsy samples from each liver, the coefficient of variation being between 13% and 36% (mean, 23%). Several differences were noted between the amount of collagen present according to hydroxyproline measurement and the stages of fibrosis according to histology. CONCLUSIONS: Although increases in collagen content (by hydroxyproline) approximately paralleled increases in fibrosis stage (by histology), there was considerable overlap and some discrepancies. Much work remains to be done to clarify the significance of the apparent huge variations in fibrosis within diseased livers. It is advisable for clinicians to interpret staging diagnoses by histological staging with some caution.

Adolescent↗
PubMed1987

Urinary hydroxyproline excretion in the myelofibrosis-osteomyelosclerosis syndrome and related diseases.

The total urinary hydroxyproline excretion was assessed in 47 patients with chronic myeloproliferative disorders. Urinary hydroxyproline excretion was normal in 16 patients with idiopathic myelofibrosis and in 5 out of 6 patients with acute myelofibrosis. In patients with osteomyelosclerosis (n = 8) values for urinary hydroxyproline excretion were higher (median 202, range 54-652) than those in idiopathic myelofibrosis (median 139, range 84-216). This difference was not significant (p greater than 0.1). Elevated values for urinary hydroxyproline excretion were found in 10 patients (1 AMF patient, 3 OMS patients and 6 patients with CML in the accelerated phase of the disease). All but 1 of these patients had been treated, or were being treated, with cytotoxic agents at the time of investigation. These findings are compatible with impaired degradation of bone marrow collagen which, together with enhanced collagen synthesis from bone marrow fibroblasts, accounts for progressive accumulation of connective tissue in the bone marrow. This process appears to be influenced by cytotoxic treatment as reflected in increased urinary hydroxyproline excretion in those patients receiving cytotoxic agents.

Bone Marrow↗
PubMed1979

Hydroxyproline metabolism in two sisters with hydroxyprolinemia.

Hydroxyproline metabolism was evaluated in two sisters with hydroxyprolinemia and their mother. 33 and 21% of an oral hydroxyproline load (200 mg/kg) was excreted by the sisters, 5.4% by the mother, and 1.3% by normal subjects. Plasma and erythrocyte values in the sisters and their mother were elevated, indicating that extra- and intracellular hydroxyproline pools were increased. Analysis for urinary glycolate and oxalate (metabolic products of hydroxyproline) showed no increased excretion by the two sisters, although the mother's excretion was normal. A deficiency of hydroxyproline oxidase in the two sisters was indicated by the lack of delta 1-pyrroline-3-hydroxy-5-carboxylic acid excretion.

Adult↗
PubMed1977

Urinary hydroxyproline concentration in primary hyperparathyroidism with and without renal stones.

Eleven cases with histologically confirmed primary hyperparathyroidism have been studied. Although histologically, bone turnover increased in all but 1 patient, urinary hydroxyproline excretion and serum alkaline phosphatase in patients with renal stones were within the upper normal limits of slightly elevated (27.5 mg/24 h, concentration 19.5 microgram/ml, alkaline phosphatase 35.0 IU/l). On the contrary, 3 cases without renal stones exhibited an increased urinary hydroxyproline excretion (129 mg/24 h, concentration 95.6 microgram/ml) and elevated serum alkaline phosphatase (99.9IU/l). Serum total hydroxyproline was elevated in both groups (renal stones, 2.00 mg%; no renal stones, 3.16 mg%; p = 0.006). Hydroxyproline was determined under conditions of a very low proline diet and 1.5 liters of daily fluid intake. There were no statistically significant differences between serum calcium, phosphorus, and parathormone between urinary excretion of calcium and phosphorus. Creatinine clearance was within normal limits in all patients. The possible relevance of urinary hydroxyproline for stone formation is discussed.

Adult↗
PubMed1982

Hydroxyproline and passive stiffness of pressure-induced hypertrophied kitten myocardium.

Passive stiffness and hydroxyproline content of myocardium hypertrophied by pressure-loading were determined in kittens 2, 8-16, and 24-52 wk after pulmonary artery banding, which initially elevated right ventricular systolic pressure by 10-15 mm Hg. Right ventricular mass increased by approximately 75%, three-quarters of which occurred during the first 2 wk after banding. Passive stiffness was assessed from resting length-tension relations of isometrically contracting isolated right ventricular papillary muscles. Stiffness constants, alpha and beta were determined from the relationship sigma = alpha (e beta epsilon - 1) where sigma = stress and epsilon = Lagrangian strain. Elastic stiffness (d sigma/d epsilon) was derived from: d sigma/d epsilon = beta sigma + beta alpha. Right ventricular hydroxyproline increased in proportion to muscle mass so that hydroxyproline concentration remained unchanged after banding. Both alpha, beta, and elastic stiffness-stress relations were similar to values in nonbanded controls. Thus, we did not observe an increase in passive stiffness or hydroxyproline concentration of pressure-stiffness or hydroxyproline concentration of pressure-induced hypertrophied myocardium in contrast to most previous studies.

Animals↗
PubMed1976

Type I hyperprolinemia: a study of the intestinal absorption of proline, hydroxyproline, and glycine.

Intestinal absorption of proline, hydroxyproline, and glycine was interpreted by investigation of a type I hyperprolinemia patient and six control subjects. Intestinal perfusion was performed. When proline (Pro), hydroxyproline (OH-Pro), and glycine (Gly) were infused together, an increase in proline concentration did not alter aminoacid uptake in the control subjects; however, in the hyperprolinemia patient, uptake of aminoacids became negliglible (Pro, 17--6 muM/min; OH-Pro, 15--0.3 muM/min; and Gly, 13.5--0 muM/min). When each aminoacid was infused alone at increasing concentrations aminoacid uptake increased in controls; in the hyperprolinemic patient, intestinal absorption was less for glycine and hydroxyproline but aminoacid uptake increased with substrate concentration; however, for proline, the uptake remained constant (1l.5--17 muM/min/20 cm of intestinal test segment) (Table 1). When hydroxyproline was infused with an increased concentration of proline in the hyperprolinemic patient, hydroxyproline uptake first increased (9.8--14.3 muM/min/20 cm) then decreased to its basal value, whereas, in the control subjects, uptake increased without decreasing subsequently.

Biological Transport↗
PubMed2006

Angelica sinensis down-regulates hydroxyproline and Tgfb1 and provides protection in mice with radiation-induced pulmonary fibrosis.

Pulmonary fibrosis is a common delayed side effect of radiation therapy, and it has a poor prognosis. Tgfb1 is a potent chemoattractant for fibroblasts and stimulates the production of collagen, the protein that contains hydroxyproline. Since collagen is by far the most abundant protein in the lung, comprising 60-70% of the tissue mass, analysis of the hydroxyproline content in lung tissues provides a reliable quantitative index for pulmonary fibrosis. Thus hydroxyproline and Tgfb1 may be involved in the development of fibrosis. In this study, we investigated radiation-induced pulmonary fibrosis in a mouse model. C57BL/6 mice were assigned into four groups: no treatment, treated with Angelica sinensis treated only, X-irradiated only (a single fraction of 12 Gy to the thorax), and Angelica sinensis treatment plus radiation. We assayed expression of hydroxyproline and the mRNA and protein of Tgfb1 in the four groups. We found that Angelica sinensis down-regulated the production of Tgfb1 and hydroxyproline in mice with radiation-induced pulmonary fibrosis. This study has demonstrated for the first time that Angelica sinensis inhibits the progress of radiation-induced pulmonary fibrosis, possibly by down-regulating the expression of the proinflammatory cytokine Tgfb1. These data suggest that Angelica sinensis may be useful in preventing and/or treating radiation-induced pulmonary fibrosis in the clinic.

Angelica sinensis↗
PubMedDate not supplied

Value of hydroxyproline measurements in the assessment of late radiation enteropathy.

In female Wistar rats roentgen irradiation of a 10 cm long temporarily exteriorized mid small intestinal segment was performed. Hydroxyproline, proline, aspartic acid and threonine were measured in intestinal samples 2 to 44 weeks after single or fractionated irradiation, and compared with a histopathologic radiation injury score in order to determine their value as assays of late radiation enteropathy. Two to 4 weeks after irradiation there was good correlation between the histopathologic injury score and the content of hydroxyproline. During the late observation period, there was no difference in hydroxyproline concentration between irradiated and sham-irradiated animals. There was no difference in hydroxyproline concentration in samples from the 1, 2 or 3 fractions groups, although the relative amount of non-collagen protein seemed to increase with fractionation. Determination of the hydroxyproline concentration may be used as an assay of early radiation injury, but it seems to be less suitable for late radiation enteropathy assessment.

Animals↗
PubMed1976

Hydroxyproline in serum as a homeostatic index for calcium in cattle.

Hydroxyproline, calcium, magnesium, phosphorus, and alkaline phosphatase values were determined in serum over 24 h in Holstein cows. The cows represented two age groups and three percents of diet calcium. Hydroxyproline followed a cyclic pattern dipping at 0800 and 1600 h after milking at 0500 and 1530 h. Phosphorus showed a 24 h rhythm peaking at 1600 h. No other time effects were demonstrated. Hydroxyproline and alkaline phosphatase were both lower in the older cows, indicating a decreased calcium mobilization from bone with age. There was a correlation coefficient of only .20 between serum calcium and hydroxyproline. The calcium concentration in serum was maintained within a narrow range presumably as a result of homeostatic mechanisms involving bone resorption, i.e. the release of calcium and hydroxyproline may indicate the degree of homeostasis required to maintain serum calcium.

Age Factors↗