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PubMed1976

[Urinary excretion of hydroxyproline in acromegaly (author's transl)].

Urinary excretion of hydroxyproline was examined with the Hypronosticon test in 25 patients with acromegaly (13 men, 12 women) and 15 healthy persons. At the same time, plasma levels and urinary excretion of phosphorus and calcium were also measured. Patients with active acromegaly had a significantly higher urinary hydroxyproline output (32.55 +/- 8.68 mg/24 h m2) than healthy persons (12.12 +/- 2.33 mg/24 h-m2). They also excreted considerably more hydroxyproline than patients with successfully treated acromegaly. Effective treatment was proved by STH levels and good suppressibility by 100 mg glucose. Unsucessfully treated patients, on the contrary, had a raised urinary excretion of hydroxyproline (31.23 +/- 16.61 mg/24 h-m2) and high fasting plasma levels of somatotropic hormone. Hydroxyprolinuria proved, therefore, of value in assessing the development and treatment of acromegaly.

Acromegaly↗
PubMed1984

The activity of the bone isoenzyme of serum alkaline phosphatase and urinary hydroxyproline excretion in premenopausal and postmenopausal women with primary hyperparathyroidism.

Estrogen deficiency might increase responsiveness of bone to circulating endogenous parathormone. To explore a possible relationship between parathormone action on bone and estrogens we studied the activity of the bone isoenzyme of serum alkaline phosphatase and the urinary excretion of hydroxyproline in 16 premenopausal and 24 postmenopausal women with primary hyperparathyroidism with hyperparathyroid osteodystrophy. The postmenopausal women with primary hyperparathyroidism had the B-ALP 4.30 +/- 0.54 mukat/l, the urinary hydroxyproline excretion 205.2 +/- 22.2 mmol/mol creatinine and urinary calcium excretion 8.9 +/- 0.5 mmol/24 hours, significantly increased in comparison with the group of women with menstrual cycle and primary hyperparathyroidism who had B-ALP 2.12 +/- 0.43 mukat/l, the urinary hydroxyproline excretion 119.0 +/- 14.9 mmol/mol creatinine and urinary calcium excretion 7.7 +/- 0.4 mmol/24 hours. Evidence supporting that estrogen deficiency might increase responsiveness of bone to circulating endogenous parathormone was provided by the demonstration that postmenopausal women with primary hyperparathyroidism had increased bone turnover assessed by urinary hydroxyproline excretion and bone isoenzyme of alkaline phosphatase in comparison with the group of premenopausal women with primary hyperparathyroidism.

Adolescent↗
PubMed1985

Hydrochlorothiazide lowers urinary hydroxyproline in parathyroidectomized rats.

This study was undertaken to examine the effects of hydrochlorothiazide treatment on urinary hydroxyproline excretion in parathyroidectomized rats. Urinary hydroxyproline (mumol/24 hr) fell significantly in thiazide-treated rats compared with control animals (5.66 +/- 0.37 versus 7.30 +/- 0.6, P less than 0.05, means +/- SEM). This fall in hydroxyproline excretion occurred without a decrease in glomerular filtration rate. It is concluded that the ability of thiazide diuretics to reduce urinary hydroxyproline excretion is not dependent upon suppression of parathyroid hormone-mediated bone turnover.

Animals↗
PubMed1982

Effect of dexamethasone and cyclophosphamide on urinary hydroxyproline to creatinine ratios in sheep.

The possibility of altering bone collagen turnover rates by injecting large doses of dexamethasone or by administering large doses of cyclophosphamide orally was investigated in sheep on low and high dietary intakes by measuring changes in the ratios of free and total hydroxyproline to creatinine and of calcium to creatinine in the urine. Dexamethasone at the rate of 1.15 mg/kg live weight caused an increase in free hydroxyproline excretion of 111 and 26% and in calcium excretion of 402 and 243% in the low and high intake sheep respectively. Cyclophosphamide (10 mg/kg) had little effect except for causing a slight decrease in total hydroxyproline excretion in the sheep on the high dietary intake. Heavier sheep on high dietary intakes excreted more free hydroxyproline than lighter sheep on low intakes. It was concluded that dosing sheep with corticosteroids for the purpose of defleecing could cause abnormal collagen metabolism. Skeletal disorders are a likely result but further long-term field work would be necessary to determine the practical significance of these findings.

Animals↗
PubMed2001

Unhydroxylated triple helical collagen I produced in transgenic plants provides new clues on the role of hydroxyproline in collagen folding and fibril formation.

Human unhydroxylated homotrimeric triple-helical collagen I produced in transgenic plants was used as an experimental model to provide insights into the role of hydroxyproline in molecular folding and fibril formation. By using chemically cross-linked molecules, we show here that the absence of hydroxyproline residues does not prevent correct folding of the recombinant collagen although it markedly slows down the propagation rate compared with bovine fully hydroxylated homotrimeric collagen I. Relatively slow cis-trans-isomerization in the absence of hydroxyproline likely represents the rate-limiting factor in the propagation of the unhydroxylated collagen helix. Because of the lack of hydroxylation, recombinant collagen molecules showed increased flexibility as well as a reduced melting temperature compared with native homotrimers and heterotrimers, whereas the distribution of charged amino acids was unchanged. However, unlike with bovine collagen I, the recombinant collagen did not self-assemble into banded fibrils in physiological ionic strength buffer at 20 degrees C. Striated fibrils were only obtained with low ionic strength buffer. We propose that, under physiological ionic strength conditions, the hydroxyl groups in the native molecule retain water more efficiently thus favoring correct fibril formation. The importance of hydroxyproline in collagen self-assembly suggested by others from the crystal structures of collagen model peptides is thus confirmed experimentally on the entire collagen molecule.

Animals↗
PubMed1977

Hydroxyproline index as a tool for nutrition status surveys in malarial regions.

1. The efficiency of the urinary hydroxyproline index as an indicator of nutrition status in mass surveys was investigated. The index was determined in 364 children aged under 5 years who participated in the National Nutrition Status Survey of the Republic of Zambia. The results of these biochemical investigations are given for all children and also according to the presence of various tropical parasitic diseases. 2. In rural areas of Zambia the hydroxyproline index was not related to the age of the child during the first 5 years of life. A lower nutritional status as defined by weight-for-age was associated with a lower hydroxyproline index. 3. The main factor affecting the index was the presence of malaria parasites in the blood. Malaria was associated with a lower index in all circumstances investigated, including children with definite growth failure. The mean of the index for healthy children was 2-49. 4. It is concluded that the index is of value in surveys but only in addition to other assessments of nutritional status. In regions where malaria is endemic the index may be of little value in determining nutritional status unless the presence of malaria parasites in the blood is investigated in all subjects and interpretation of the hydroxyproline index where malaria is confirmed is very complex.

Ancylostomatoidea↗
PubMed1983

Structural aspects of hydroxyproline-containing proteins.

The occurrence of hydroxyproline (Hyp) in collagen, C1q and acetylcholineesterase (AChE) raises important questions concerning the role of this unusual imino acid in the structure and function of these proteins. Available data on collagen indicate that Hyp is necessary for the normal secretion of the protein after its synthesis and for the integrity of the triple-helical conformation. Studies from our laboratory have dealt with the structural aspects of the posttranslational conversion of proline to hydroxyproline in collagen mediated by prolyl hydroxylase. We proposed that the beta-turn conformation at the Pro-Gly segments in the nascent procollagen molecule are the sites of the enzymatic hydroxylation and that this conformation changes over to the collagen-like helix as a result of the hydroxylation process. Recently, we have provided additional experimental support to our proposal by a) synthesizing specific beta-turn oligopeptides containing the Pro-Gly as well as Pro-Ala and Pro-DAla sequences and showing that these act as inhibitors of the enzymatic hydroxylation of a synthetic substrate and b) demonstrating, by circular dichroism spectroscopy, the occurrence of a conformational change leading to the triple-helix as a direct consequence of proline hydroxylation in a non-helical polypeptide substrate. We have also observed that the acquisition of hydroxylation results in a significant enhancement of the rate of folding of the polypeptide chain from the unfolded to the triple-helical conformation. We believe that our observations on proline hydroxylation in collagen should also be applicable to C1q and acetylcholineesterase both of which share the general structural and functional properties of collagen in their "tail" regions. Using the techniques employed in collagen studies, one should be able to assess the role of hydroxyproline in the folding, structural stabilities and functions of C1q and AChE. This would also involve the study of the unhydroxylated and hydroxylated precursors of these proteins which may share common structural features with their collagen counterparts. Finally, a systematic study of hydroxyproline-containing peptides and polypeptides has been initiated by us so as to understand the exact manner in which Hyp participates in the formation and stability of the triple-helical conformation in the proteins in which it occurs.

Acetylcholinesterase↗
PubMed1990

Urinary hydroxyproline excretion and vitamin C status in healthy young men.

The relationship between ascorbic acid status and the urinary excretion of hydroxyproline was examined in 11 healthy male subjects fed an ascorbic acid-deficient diet for 14 wk while in a metabolic unit. The diet provided 5 mg ascorbic acid/d and was supplemented with ascorbic acid to give intakes of 65 mg/d (2 wk), 5 mg/d (4 wk), 605 mg/d (3 wk), 5 mg/d (4 wk), and an average 375 mg/d (1 wk). The urinary excretion of hydroxyproline increased by an average of 16% and 30% after the first and second depletion periods, respectively, and decreased to baseline values after supplementation with normal or high doses of vitamin C. Significant (p less than 0.05) inverse correlations were found between urinary hydroxyproline and plasma, red cell, and leukocyte ascorbic acid. These results show that urinary hydroxyproline excretion increases during human vitamin C deficiency but that this effect is not strong enough to provide a reliable marker of mild vitamin C deficiency.

Adult↗
PubMed1981

Renal acid, urinary cyclic AMP, and hydroxyproline excretion as affected by level of protein, sulfur amino acid, and phosphorus intake.

Two 51-day human studies were conducted to investigate the effects of level of protein and phosphorus intake on the various components of renal acid excretion and on urinary sulfate, cyclic AMP and hydroxyproline; the role of the sulfur amino acids (Saa) of the protein was also evaluated. Dietary treatments included: 1) a 50 g protein diet; 2) a 150 g protein diet; and 3) a 50 g protein diet plus Saa to equal that of the 150 g protein diet, each given at 2 levels of phosphorus (1010 and 2525 mg). Calcium intake was 500 mg. Subjects were 16 young adult males. The results are discussed in relationship to calcium data previously reported (1, 2). Changes in renal acid and calcium excretion are not directly related for these reasons: a) the Saa accounted for all of the protein-induced increase in urinary sulfate and acid but for only 43% of the increase in urinary calcium and b) the acid phosphate supplement decreased urinary calcium but increased total acid excretion. The phosphorus supplement increased cyclic AMP but not hydroxyproline excretion. In fact, protein and Saa caused increases in hydroxyproline that were greatly reduced by the phosphorus supplement. Increases in urinary hydroxyproline and calcium were well correlated indicating that, at low calcium intakes, protein or Saa-induced increases in urinary calcium result in increased bone resorption which is reduced by the administration of phosphorus.

Acids↗
PubMedDate not supplied

Urinary excretion of glycosaminoglycans, hydroxyproline and hydroxylysine in rabbits after excessive ingestion of fluoride.

Urinary levels of glycosaminoglycans (GAG) and hydroxyproline from normal and fluoride treated rabbits were estimated. The hydroxylysine content of serum and urine of rabbits after excessive ingestion of fluoride was also investigated. There was a progressive decrease in GAG content, reduction in hydroxylysine, whereas the hydroxyproline content was increased after fluoride ingestion. Enhanced hydroxyproline in urinary excretion is due to collagen breakdown after fluoride ingestion. The reduction in hydroxylysine content is due to reduced collagen cross-link formation. The report suggests the possibility of using the urinary levels of GAG or hydroxyproline or hydroxylysine as an index of fluoride intoxication.

Animals↗
PubMed2006

Effects of sucralfate, cimetidine and rabeprazole on mucosal hydroxyproline content in healing of ethanol-hcl-induced gastric lesions.

1. No general consensus has been reached on the treatment of acute gastric lesions. The aims of the present study were to clarify the effects of sucralfate, cimetidine and rabeprazole monotherapies and combination therapies on acute gastric lesions from the viewpoint of connective tissue regeneration. 2. Gastric lesions were experimentally created by the oral administration of 50% ethanol-0.15 mol/L HCl to rats. After 30 min, the anti-ulcer agents sucralfate (100 mg/kg), cimetidine (20 mg/kg) and rabeprazole (2 mg/kg) were administered separately or in combination and the stomach was excised at different times to measure the level of hydroxyproline in the gastric mucosa and determine lesion index. Immunostaining against prolylhydroxylase was performed on some specimens. 3. In the control group, lesion index decreased linearly from 30 min after ethanol-HCl administration and the level of mucosal hydroxyproline peaked between 2 and 4 h later. Although sucralfate significantly promoted lesion healing, it had no effect on mucosal hydroxyproline level. Cimetidine suppressed increases in mucosal hydroxyproline and prolonged lesion healing, but these findings were reversed by combining cimetidine and sucralfate. Rabeprazole had no significant effect on lesion healing, but promoted lesion healing in combination with sucralfate. Immunohistochemical analysis showed that prolylhydroxylase was expressed in spindle cells that lined the glandular cells in a boundary area between normal and injured tissues. 4. Under conditions in which the effects of intragastric pH are minimal, sucralfate is superior to antisecretory agents in promoting the healing of acute gastric lesions.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1990

A hydroxyproline-containing protein from shark brain that is related to myelin basic protein.

Myelin basic protein (MBP) from shark (Chondricthyes) consists of a simpler mixture of charge isomers than human MBP. About two-thirds of the total amount applied to a CM-52 cellulose cation-exchange column was recovered in the unbound fraction of the column; the remaining one-third bound to column and was eluted as a single OD280 peak. This bound material did not sow the usual pattern of charge microheterogeneity found with human or bovine MBP. The unbound fraction was composed of a high molecular weight protein (55-60 kDa), which constituted most of this protein fraction and a low molecular weight protein (approximately 18 kDa). The amino acid composition of our unbound fraction was similar to that reported earlier. The Glx (glutamic acid + glutamine) was increased about threefold whereas the Arg content was only about 25% of that of the 18.5 kDa variant of bovine or human origin. The presence of hydroxyproline (1.2 residues/100) in this protein was noteworthy, identification of which was achieved by amino acid analysis in two different systems and by mass spectrometry. In the precolumn derivatization method, hydroxyproline eluted at 2.7 min; in the postcolumn derivatization method it eluted at 12.2 min. Identification of hydroxyproline was completed by fast atom bombardment-mass spectral analysis. The effect of hydroxyproline on the secondary structure of this protein is being studied. Verification that this high molecular weight protein contained MBP sequences within its primary structure was confirmed by immunological methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Vacuolar chitinases of tobacco: a new class of hydroxyproline-containing proteins.

The fungicidal type I chitinases contribute to the defense response of plants against pathogens. Two tobacco chitinases represent a different class of hydroxyproline-containing proteins. Hydroxyproline-rich proteins are predominantly extracellular, structural glycoproteins proteins that lack enzymatic activity and contain many hydroxyproline residues. In contrast, type I chitinases are vacuolar enzymes. They are not glycosylated and contain a small number of hydroxyproline residues restricted to a single, short peptide sequence.

Amino Acid Sequence↗
PubMed2005

Mitochondrial hydroxyproline metabolism: implications for primary hyperoxaluria.

BACKGROUND/AIMS: Primary hyperoxaluria results from an alteration in enzymes that metabolize glyoxylate. The metabolism that leads to glyoxylate synthesis is not well defined. The aim of this study was to investigate the production of glyoxylate in liver mitochondria when they metabolize hydroxyproline. METHODS: Mitochondria were isolated from mouse liver using Percoll gradient centrifugation. The metabolism of hydroxyproline was examined by a combination of HPLC and ion chromatography/mass spectrometry techniques. RESULTS: Glyoxylate production was substantially greater when mitochondria were incubated with hydroxyproline in comparison with proline. Inclusion of malate and glutamate with hydroxyproline resulted in a drop in glyoxylate and an increase in glycolate in the incubation mixture. This suggests an increased NAD(P)+ reduction which occurred with the inclusion of glutamate/malate and that the NAD(P)H production was required to stimulate the glyoxylate reductase-catalyzed conversion of glyoxylate to glycolate. The presence of glyoxylate reductase in these mitochondria was confirmed by measuring enzymatic activity and by Western blotting. CONCLUSION: These results indicate that studies on isolated mitochondria have the potential to help unravel the metabolism associated with glyoxylate and oxalate production and understand the metabolic function of glyoxylate reductase.

Animals↗
PubMed1984

Study of serum and urine hydroxyproline level of patients with prostatic cancer.

The serum and urine hydroxyproline levels of patients with prostatic cancer were regularly studied for 30 months. Bone metastases were found in 4 patients at the beginning of the study; metastases formed in 8 patients during the test period, and in 9 patients no metastases formed during the study. At the time of X-ray diagnosis of metastasis, significantly higher serum and urine hydroxyproline levels and enzymatic phosphatase were found, but in the tests performed 3 months earlier, in spite of the negative X-ray results, the hydroxyproline results differed significantly from the reference values. The above findings support the use of the hydroxyproline test for the diagnosis of metastases.

Aged↗
PubMed1983

Myocardial hydroxyproline and mechanical response to prolonged pressure loading followed by unloading in the cat.

To determine the myocardial response to prolonged pressure-loading and unloading, kittens weighing 0.8-1.2 kg underwent pulmonary artery banding, which initially elevated right ventricular (RV) systolic pressure by 10-15 mm Hg. 52 and 76 wk later; RV weight/body weight had increased by approximately 80%. Total RV hydroxyproline had increased significantly, whereas hydroxyproline concentration was unchanged from that of nonbanded animals of comparable age. In isometrically contracting RV papillary muscles, peak active force was significantly less at 76 wk (3.3 +/- 0.8 [SD] g/mm2 than at 52 wk (5.1 +/- 0.8 g/mm2) or in nonbanded animals (4.8 +/- 0.8 g/mm2). Velocity of muscle shortening at comparable loads was unchanged after 52 wk but was significantly less after 76 wk. In nonstimulated, slowly stretched muscles, passive stiffness constants, alpha and beta, derived from delta = alpha(e beta epsilon - 1), where delta is instantaneous stress and epsilon is Lagrangian strain, were unchanged by banding. The band was removed after 52 wk in additional animals that were studied 24 wk later. In those animals with normal RV pressures at death, hypertrophy had regressed and hydroxyproline concentration was comparable to that of nonbanded and banded animals; Active and passive mechanical function remained normal. In this model, changes in hydroxyproline parallel changes in muscle mass, and passive stiffness remains normal during development and regression of hypertrophy. Removal of the pressure load after prolonged hypertrophy prevents or retards the late development of myocardial dysfunction.

Animals↗
PubMed2005

Methods for measuring hydroxyproline and estimating in vivo rates of collagen synthesis and degradation.

A major pathogenic feature of fibrotic diseases is the excessive and disorganized deposition of collagens. This results from changes in both synthetic and degradative pathways. The posttranslational hydroxylation of proline to hydroxyproline and the relative abundance of hydroxyproline in collagens, compared with other proteins, facilitates its use as a relatively specific marker of collagen content and metabolism. This chapter describes in vivo methods for the estimation of collagen synthesis and degradation rates, as well as the proportion of newly synthesised collagen rapidly degraded intracellularly. These pathways have all been shown to play important roles in the altered deposition of collagen associated with the development of fibrosis. The methods are based on the incorporation of radiolabeled proline into collagen as hydroxyproline and its measurement in intact protein and collagen breakdown products. In addition, an accurate and highly sensitive high-performance liquid chromatography method is described for the measurement of hydroxyproline for in vivo and in vitro studies.

Animals↗
PubMed1989

Changes in the concentrations of hydroxyproline, glycine and serine in the plasma of haemodialysis patients undergoing erythropoietin therapy.

The concentrations of proline, hydroxyproline, glycine and serine were determined in the plasma of 39 haemodialysis patients and 18 healthy subjects, using liquid chromatography with fluorescence detection. Plasma concentrations of the N-terminal immunoreactive parathyrin were also measured. In haemodialysis patients, the plasma concentrations of glycine (p less than 0.01), hydroxyproline (p less than 0.05) and proline (p less than 0.10) were significantly increased, whereas the serine concentrations (p less than 0.01) were decreased, compared with those of the healthy controls. Haemodialysis patients showed greatly elevated plasma N-terminal immunoreactive parathyrin values (greater than 30 pmol/l), which showed a significant correlation with the hydroxyproline values (r = 0.79). Fourteen haemodialysis patients received erythropoietin therapy. In these patients, changes in the concentrations of plasma amino acids were observed up to one year after the beginning of therapy. In the course of the erythropoietin therapy, the plasma concentrations of glycine (p less than 0.05) and hydroxyproline (p less than 0.10) of the haemodialysis patients decreased, whereas the concentration of serine increased (p less than 0.05) to approximately normal values. The results indicate that erythropoietin therapy leads to a normalization of amino acid metabolism.

Adult↗