Significance of urinary hydroxyproline in man

Oral Supplementation of Collagen Peptides Improves Skin Hydration by Increasing the Natural Moisturizing Factor Content in the Stratum Corneum: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

INTRODUCTION

We aimed to investigate the effect of orally ingested collagen peptides (CPs) on skin condition and elucidate their mechanism of action.

METHODS

A randomized, placebo-controlled, double-blind trial was conducted in 99 healthy Japanese women, aged 35-50 years. The subjects were randomized into 3 groups (33 subjects/group) to receive 1 or 5 g of CP or placebo once daily for 12 weeks. Skin water content, transepidermal water loss (TEWL), skin elasticity, and skin thickness were evaluated before treatment and after 4, 8, and 12 weeks of treatment. The level of natural moisturizing factor (NMF) constituents in the stratum corneum (SC) was quantified before treatment and after 12 weeks of treatment.

RESULTS

Oral ingestion of CP increased the water content in the SC and epidermis and decreased TEWL. Furthermore, the NMF level in the SC was increased. However, skin elasticity and skin thickness remained unchanged.

CONCLUSIONS

The improvement in skin water content following the oral ingestion of CP can be attributed to an increase in the level of NMF in the SC.

TRIAL REGISTRATION

UMIN000030375 (retrospectively registered).

A systematic comprehensive longitudinal evaluation of dietary factors associated with acute myocardial infarction and fatal coronary heart disease

Environmental factors, and in particular diet, are known to play a key role in the development of Coronary Heart Disease. Many of these factors were unveiled by detailed nutritional epidemiology studies, focusing on the role of a single nutrient or food at a time. Here, we apply an Environment-Wide Association Study approach to Nurses' Health Study data to explore comprehensively and agnostically the association of 257 nutrients and 117 foods with coronary heart disease risk (acute myocardial infarction and fatal coronary heart disease). After accounting for multiple testing, we identify 16 food items and 37 nutrients that show statistically significant association - while adjusting for potential confounding and control variables such as physical activity, smoking, calorie intake, and medication use - among which 38 associations were validated in Nurses' Health Study II. Our implementation of Environment-Wide Association Study successfully reproduces prior knowledge of diet-coronary heart disease associations in the epidemiological literature, and helps us detect new associations that were only marginally studied, opening potential avenues for further extensive experimental validation. We also show that Environment-Wide Association Study allows us to identify a bipartite food-nutrient network, highlighting which foods drive the associations of specific nutrients with coronary heart disease risk.

Urinary Hydroxyproline Is Only Suitable As a Biomarker for Acute Intake, Up to 6 hr Postingestion of Collagen Proteins in "Free-Living," Healthy, Active Males

The urinary excretion of hydroxyproline (Hyp), abundant in collagen protein, may serve as a biomarker of habitual collagen intake, assisting with investigations of current interest in the role of dietary collagen intake in supporting the synthesis of collagenous body tissues. This study investigated the time course of urinary Hyp excretion in "free-living," healthy, active males following the ingestion of a standardized bolus (20 g) of collagenous (gelatin and a hydrolyzed collagen powder) and dairy (calcium caseinate and hydrolyzed casein) proteins. The excretion of Hyp was assessed over a 24-hr period, separated into three collection periods: 0-6, 6-12, and 12-24 hr. Hyp was elevated for 0-6 hr after the consumption of collagen-containing supplements (gelatin 31.3 ± 8.8 mmol/mol and hydrolyzed collagen 33.7 ± 22.0 mmol/mol vs. baseline: gelatin 2.4 ± 1.7 mmol/mol and hydrolyzed collagen 2.8 ± 1.5 mmol/mol; p < .05), but not for the dairy protein supplements (calcium caseinate 3.4 ± 1.7 mmol/mol and hydrolyzed casein 4.0 ± 3.7 mmol/mol; p > .05). Therefore, urinary Hyp reflects an acute intake of collagenous protein, but is not suitable as a biomarker for quantifying habitual collagen intake, provided through regular dietary practices in "free-living," healthy, active males.

Improved in Vivo Tracking of Orally Administered Collagen Hydrolysate Using Stable Isotope Labeling and LC-MS Techniques

Collagen-derived hydroxyproline (Hyp)-containing oligopeptides, known to have various physiological functions, are detected in blood at markedly higher concentrations after oral ingestion of collagen hydrolysate. Monitoring the absorption and metabolism of the bioactive peptides is essential to investigate the beneficial effects of collagen hydrolysate. We previously developed an internal standard mixture by sequential protease digestion of stable isotope-labeled collagen, which enabled highly accurate quantitation of collagen-derived oligopeptides by liquid chromatography-mass spectrometry (LC-MS). However, the use of proteases caused a profound imbalance in the generated peptides. Here, we employed partial acid hydrolysis to achieve more efficient and balanced peptide generation. Various stable isotope-labeled oligopeptides were detected after 0.5 h acid hydrolysis, and marked enhancement of peptide generation compared with the previous enzymatic method was observed, especially for Hyp-Gly (27.8 ± 0.6 ng/μg vs 0.231 ± 0.02 ng/μg). The acid hydrolysate was then heated to generate labeled cyclic dipeptides. Using the novel internal standard mixture in LC-MS, we were able to simultaneously quantitate 23 collagen-derived oligopeptides in human plasma and urine after oral administration of collagen hydrolysate.

Urinary Hydroxyproline in Multiple Myeloma: Correlation with Clinical Stages and Bone Disease

Twenty-four-hour urinary hydroxyproline excretion (HOP) (normal values: 6–22 mg/day/m2) was measured by the Hypronosticon test in 50 untreated patients with plasma cell myeloma. At diagnosis, HOP was elevated in 36 of 50 patients (72 %) with a mean value of 35.9 mg/day/m2. Extent of bone lesions and clinical stage were accurately assessed in all patients. Higher HOP values were found in patients with a higher degree of bone lesions (multiple lytic areas and/or destruction of skeletal segments). According to clinical stages, HOP was very elevated only in stage III (mean value: 43.7); in stages I and II the mean value (25.2) was just above the normal range. Our data indicate that HOP in multiple myeloma at diagnosis is closely related to the extension of skeletal lesions and that during the clinical course it may be useful in the follow-up of bone disease.

Diverse characteristics of the urinary excretion of amino acids in humans and the use of amino acid supplementation to reduce fatigue and sub-health in adults

Background

The excretion of amino acids in urine represents an important avenue for the loss of key nutrients. Some amino acids such as glycine and histidine are lost in higher abundance than others. These two amino acids perform important physiological functions and are required for the synthesis of key proteins such as haemoglobin and collagen.

Methods

Stage 1 of this study involved healthy subjects (n = 151) who provided first of the morning urine samples and completed symptom questionnaires. Urine was analysed for amino acid composition by gas chromatography. Stage 2 involved a subset of the initial cohort (n = 37) who completed a 30 day trial of an amino acid supplement and subsequent symptom profile evaluation.

Results

Analyses of urinary amino acid profiles revealed that three groups could be objectively defined from the 151 participants using k-means clustering. The amino acid profiles were significantly different between each of the clusters (Wilks’ Lambda = 0.13, p < 0.0001). Cluster 1 had the highest loss of amino acids with histidine being the most abundant component. Cluster 2 had glycine present as the most abundant urinary amino acid and cluster 3 had equivalent abundances of glycine and histidine. Strong associations were observed between urinary proline concentrations and fatigue/pain scores (r = .56 to .83) for females in cluster 1, with several other differential sets of associations observed for the other clusters.

Conclusions

Different phenotypic subsets exist in the population based on amino acid excretion characteristics found in urine. Provision of the supplement resulted in significant improvements in reported fatigue and sleep for 81% of the trial cohort with all females reporting improvements in fatigue.

Trial registration

The study was registered on the 18th April 2011 with the Australian New Zealand Clinical Trials Registry (ACTRN12611000403932).

Polyamines, myosin heavy chains, and collagen specific amino acids after a repeated bout of eccentric exercise

We investigated alternatives to commonly used biomarkers of exercise-induced tissue damage. Over 5 days following two bouts of 100 drop-to-vertical jumps (inter-bout rest period of 3 weeks), myosin heavy chain 1, hydroxylysine (HYL), hydroxyproline (HYP), spermine (SPM) and spermine synthase (SMS) were measured in the serum of 10 participants. HYL significantly increased from 5.92 ± 1.49 ng/mL to 6.48 ± 1.47 ng/mL at 24 h. A similar trend was observed for bout 2, but without reaching significance. SPM significantly increased only after bout 1 from 0.96 ± 0.19 ng/mL at pretest to a peak level of 1.12 ± 0.26 ng/mL at 24 h, while B2 increments remained non-significant. Myosin heavy chain 1, HYP and SMS values remained below the detection limit of the applied enzyme-linked immunosorbent assay (ELISA) kit. Though HYL and SM increased after the intervention, both markers showed a large standard deviation (SD) combined with small increments. Therefore, none of the investigated biomarkers provides a meaningful alternative to commonly used damage markers.

Prolonged antibiotic use induces intestinal injury in mice that is repaired after removing antibiotic pressure: implications for empiric antibiotic therapy

Metabolic profiling of urine and fecal extracts, histological investigation of intestinal ilea, and fecal metagenomics analyses were used to investigate effects of prolonged antibiotic use in mice. The study provides insight into the effects of extended empiric antibiotic therapy in humans. Mice were administered a broad-spectrum antibiotic for four consecutive days followed by oral gavage with Clostridium butyricum, an opportunistic gram-positive pathogenic bacteria commonly isolated in fecal and blood cultures of necrotizing enterocolitis patients. Metagenomics data indicated loss of bacterial diversity after 4 days on antibiotics that was restored after removing antibiotic pressure. Histological analyses indicated damage to ileal villi after antibiotic treatment that underwent repair after lifting antibiotic pressure. Metabolic profiling confirmed intestinal injury in antibiotic-treated mice indicated by increased urinary trans-4-hydroxy-l-proline, a breakdown product of collagen present in connective tissue of ileal villi that may serve as a biomarker for antibiotic-induced injury in at risk populations.

A concomitant review of the effects of diabetes mellitus and hypothyroidism in wound healing

This paper reviews the negative impact of diabetes mellitus or hypothyroidism on wound healing, both in experimental and clinical settings. Since both are metabolic disorders of great clinical importance, special attention is given, not only to their pathophysiology, but also to their biochemical and histological effects on tissue integrity and regeneration. Also, special focus is awarded on wound healing of the gastrointestinal tract, i.e. in intestinal anastomosis, and how these disorders can lead to wound dehiscence. Since diabetes mellitus and hypothyroidism can coexist in clinical settings, more research must be directed on their influence on wound healing, considering them as one clinical entity.

Pediatric reference intervals for bone markers

Bone markers are specific bone-derived molecules that reflect bone remodeling activity and can be classified into two categories: bone formation and bone resorption markers. Children have significantly elevated bone marker levels due to high skeletal growth velocity and rapid bone turnover during childhood growth. Many physiological and pathological processes may influence bone metabolism and bone marker concentrations during childhood growth. Measurements of bone markers may be useful in investigating skeletal diseases in children and monitoring the response to treatment. This review documents recent advances in analytical methods, preanalytical considerations related to each marker and particularly highlights the most valuable bone formation markers, bone alkaline phosphatase and osteocalcin, and bone resorption markers, pyridinium cross-links and cross-linked telopeptides. Age- and sex-specific pediatric reference intervals and their limitations in clinical application are also discussed.

First report of congenital or infantile cataract in deranged proteoglycan metabolism with released xylose

AIM

To investigate the chemical pathology in the blood and lens, in cases of congenital or infantile cataract in children excreting predominantly non-reducing carbohydrates in urine.

METHODS

Urine samples from children with congenital or infantile cataract, and age and sex-matched controls, were analysed for (i) inherited errors of metabolism, (ii) paper chromatography of sugars, (iii) spectrophotometric assay of glycosaminoglycans (GAG), (iv) cetyl trimethyl ammonium bromide test, (v) electrophoresis using Alcian blue, (vi) ion exchange chromatography with IR 120 resin, and (vii) HPLC for xylose. Blood and lens material were also tested for GAG fragments and xylose. beta Glucuronidase was assayed in lymphocytes and urine.

RESULTS

Of 220 children of both sexes below 12 years of age, with congenital or infantile cataract treated in Sankara Nethralaya, Madras, India, during a period of 2 years, 145 excreted fragments of GAG (heparan and chondroitin sulphates) in their urine. There was no such excretion among the control group of 50 children. The same was found accumulated in the blood and lenses of affected children. In addition, xylose was present in small amounts in the urine and blood and xylitol was present in the lens. There was a significant elevation in the activity of beta glucuronidase in lymphocytes and urine, when compared with normals. All the above findings suggest deranged proteoglycan metabolism. As the urine contained mostly GAG fragments and very little xylose, Benedict's reagent was not reduced. This ruled out galactosaemia.

CONCLUSION

An increase of beta glucuronidase activity might have caused extensive fragmentation of GAG with resultant accumulation in the blood and lens and excretion in urine. Small amounts of xylose may have come from xylose links between GAG and core protein of proteoglycans. Owing to their polyanionic nature, GAG fragments in the lens might abstract sodium, and with it water, thereby increasing the hydration of the lens. Excessive hydration and the osmotic effect of xylitol from xylose might cause cataract. While corneal clouding has been reported in inborn acid mucopolysaccharidosis, congenital or infantile cataract with deranged metabolism of proteoglycans (acid mucopolysaccharide-xylose-protein complex) is reported in children for the first time.

Nitrogen balance studies in clinical nutrition

Nutrition support is recognized as an important cofactor in altering morbidity and mortality of hospitalized patients. Paramount in delivering proper nutrition support is the accurate determination of baseline metabolic and nutritional status, thus influencing necessary protein requirements. After nutritional intervention, routine laboratory monitoring is used to measure the efficacy and to reassess metabolic stress level. Accurate determination of nitrogen excretion (and nitrogen balance) remains the standard in prescribing and monitoring the protein and nutritional treatment regimen. This article examines nitrogen excretion determinations in the clinical setting, including proper collection techniques, laboratory measurements, and analyses and their effect upon nitrogen balance studies.

Effect of calcium pidolate on biochemical and hormonal parameters in involutional osteoporosis

The purpose of this study was to determine the value of calcium pidolate in the treatment of involutional osteoporosis. This compound has been reported to be better absorbed than other calcium salts, to lower the levels of parathyroid hormone (PTH) and to raise those of growth hormone (GH). We accordingly treated one group of 10 women suffering from involutional osteoporosis with the equivalent of 1 g elemental calcium and administered a placebo to a second group of 10 osteoporotic women whose mean age and body surface area were comparable. Basal sequential multiple analysis (SMA-12) was performed in all subjects to determine calcium, phosphorus, alkaline phosphatase (ALP) and total protein levels, the same blood samples being used for the evaluation of mean PTH, GH and osteocalcin (BGP). Urinary 24-h calcium excretion was determined and the calcium/creatinine (Ca/Cr) and hydroxyproline/Cr (HP/Cr) ratios were measured in 12-h fasting urine samples, the results being corrected for glomerular filtrate. The same parameters were measured again following a month of uninterrupted treatment. After 30 days, we observed no differences in either group as regards calcaemia, phosphataemia, ALP, total proteins, PTH, GH, BGP or 24-hour calciuria. The only noteworthy changes seen were significant decreases (P less than 0.001) in the Ca/Cr and HP/Cr ratios in the group treated with calcium pidolate. These results show that calcium pidolate at the dose administered inhibits bone resorption but does not affect the levels of PTH, GH, BGP or ALP in the medium term. Our findings indicate that it has no influence on bone formation.

Osteopenia in rheumatoid arthritis: a biochemical, hormonal and histomorphometric study

To determine whether the osteopenia of rheumatoid arthritis (RA) is due to reduction of trabecular bone mass (TBV) and/or cortical width (CW), we evaluated these parameters by bone histomorphometry; we also measured the calciotropic hormones parathormone(PTH) and calcitonin (CT), vitamin D [25(OH)D] and the biological markers of bone remodeling in a group of patients with RA. Study subjects were divided into Group C - premenopausal patients, and Group A - menopausal patients and men of the same ages. These groups were compared to two age-matched control groups, B and D. In both A vs. B and C vs. D, TBV and CW were significantly lower in patients. There were no differences in PTH or CT, but 25(OH)D was significantly reduced, and BGP, OHP/Cr and AP were raised in patients. Patients also exhibited TBV loss in more than 55% and CW loss in more than 98%. These changes suggest that the decline in bone mass, mainly cortical, but also trabecular, is due to increased bone turnover and enhanced resorption and seem to reflect intrinsic alterations of RA.

Corneal endothelium in Marfan syndrome. A clinical and specular microscopic study

Marfan syndrome is classified as a heritable disorder of connective tissue, and it has been assumed to be an inborn error of protein metabolism particularly in collagen or elastin. We examined 41 Marfan syndrome patients and found in the corneal endothelium guttata-formation, considerable cell pleomorphism, non-reflecting endothelial black spots and in some cases abnormal looking endothelial cells. The relation of pathological endothelium to lens subluxation, axial length and other corneal findings is discussed.

Assessment of an automated chemiluminescence nitrogen analyzer for routine use in clinical nutrition

An automated method of chemiluminescence analysis of nitrogen used routinely for 4 yr. Liquid samples (urine, enteral, and parenteral feeds) required simple dilution, whereas feces required a modified acid-digestion procedure, before analysis. For urine samples, the coefficient of variation was within batch from 0.9-3.6%, and between batch 4.3-7.6%. At a sample injection rate of 2 microliter/sec, the useful dynamic range, for urine diluted 1:200, was 0-14 g N/liter. Precision for fecal nitrogen analysis was 3.8-6.7% for samples of low to high nitrogen content. The correlation between this technique and an established Kjeldahl method for fecal analysis was studied (r = 0.96, slope = 1.30). The discrepancy between the methods was due to inefficient conversion of nitrogen to NH4+ during Kjeldahl digestion of feces, rather than systematic errors in chemiluminescence analysis. Reliability was as good as for other automated clinical analyzers and sample cost was ca. 0.22 pounds. It has proved possible to analyze approximately 80 samples in the working day. The efficiency of measuring 24-hr urine urea-nitrogen (UUN) and total urine nitrogen (TUN) in patients on general wards was measured. Results were obtained on 87% of TPN days, but large variations were noted in UUN/TUN from less than 30% to greater than 90% (average 75.7%) in patients receiving TPN, and from less than 55% to 100% (average 83.8%) in patients receiving enteral nutrition. In contrast, UUN/TUN was 87.0% and 84.0% in healthy subjects, fasted or receiving iv nutrition, respectively. We therefore expect that clinical nutritionists will find increasing applications for this method of nitrogen analysis.

Influence of molecular structure on half-life and hydrolysis of dipeptides in plasma: importance of glycine as N-terminal amino acid residue

To investigate the effect of molecular structure on plasma disappearance and metabolism of dipeptides, rats were injected intravenously with individual dipeptides, and at various intervals after injection, dipeptide and amino acid concentrations were measured in plasma, tissues, and urine. In addition, plasma hydrolase activity against individual dipeptides was investigated. The half-lives of Ala-Leu, Ala-Tyr, and Ala-Gln were shorter than those of dipeptides with glycine substituting for alanine. Furthermore, the increases in plasma concentrations of leucine, tyrosine, and glutamine and rates of dipeptide hydrolysis by plasma enzymes were far greater with alanyl than glycyl dipeptides. In fact, Ala-Leu behaved like a mixture of corresponding free amino acids in raising the plasma concentration of leucine while Gly-Leu did not. There was no significant difference in either plasma half-life or hydrolysis when Leu-Gly and Leu-Ala were used as substrates, but both had rapid rates of hydrolysis in plasma. In comparison to Gly-Leu, Phe-Leu and Arg-Leu had shorter half-lives and greater rates of hydrolysis in plasma. On the other hand, Asp-Leu had a slower rate of plasma hydrolysis than Gly-Leu, but its excretion in the urine was much greater than that of Gly-Leu. In contrast to Gly-Leu and Ala-Leu, Gly-Pro was detected intracellularly in liver, muscle, and particularly, kidney. In fact, the intracellular concentration of Gly-Pro in kidney was either equal to or greater than Gly-Pro concentration in plasma. Increases in intracellular amino acid concentration after injection of individual dipeptides were considerably greater in the kidney than in either liver or muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydroxyproline and creatinine levels in normal amniotic fluid

Total hydroxyproline and creatinine concentrations as well as their ratios were determined in 29 amniotic fluid samples from normal pregnancies between the 16th and 20th week of gestation. Total hydroxyproline and creatinine levels, and their ratios, were not statistically different considering either the values at each week or those of the whole 5-week period. Our results, compared with the few others reported in the literature, can provide indications useful for defining the normal range in amniotic fluid, in relation to the weeks of gestation.

Mineral balance during nutritional supplementation in adolescents with Crohn disease and growth failure

The adaptive response of whole body mineral metabolism and collagen turnover to nutritional supplementation was determined in adolescent males with Crohn disease and growth failure. Body calcium, magnesium, phosphorus, and nitrogen status was characterized in six patients before and after 3 weeks of nutritional supplementation and in five healthy age- and sex-matched controls by the metabolic balance technique; collagen turnover was assessed by urinary hydroxyproline excretion. Fecal calcium (P less than 0.05), magnesium (P less than 0.01), and nitrogen (P less than 0.01) losses were significantly greater in the Crohn disease patients compared with the controls; after dietary supplementation, only fecal magnesium excretion increased further (P less than 0.001). Approximately twofold increases in phosphorus (P less than 0.001), nitrogen (P less than 0.02), and calcium (P less than 0.05) retention occurred with nutritional supplementation, whereas the marked renal conservation of phosphorus (P less than 0.001) suggested that this mineral was a limiting nutrient. Urinary hydroxyproline excretion was reduced (P less than 0.05) compared with the control values; however, with nutritional supplementation, urinary hydroxyproline excretion increased significantly (P less than 0.02), suggesting that the soluble fraction of tissue collagen was rapidly turning over during nutritional rehabilitation. These findings suggest that the mineral deficiencies present in adolescents with Crohn disease and growth failure can be reversed with nutritional supplementation. Furthermore, the improvement in nutritional status is reflected in the restoration of collagen-containing tissues of the body. However, nutrient imbalances may be present during nutritional therapy, thereby preventing optimal recovery from malnutrition.

Ectopia lentis

Ectopia lentis was first described more than 200 years ago, but its value as a significant diagnostic clue to the presence of other ocular and systemic disorders has only recently been appreciated. Ectopia lentis may cause a marked reduction in visual acuity, which varies with the type and degree of dislocation and the presence of other ocular abnormalities. An approach to the diagnostic evaluation of the patient with ectopia lentis is outlined. The differential diagnosis is reviewed in detail both clinically and histologically. The complications of ectopia lentis and the appropriate management of affected patients are discussed.

Urinary excretion of hydroxyproline in workers occupationally exposed to vibration

Urinary hydroxyproline excretion was measured in 130 chain saw operators aged 28-59 and in 31 normal control subjects aged 26-59 with no occupational exposure to vibration. The results measured were expressed as a ratio of hydroxyproline to creatinine. (1) No significant correlation between hydroxyproline/creatinine ratio and age was observed among normal subjects. (2) In chain saw operators grip and pinch strength decreased gradually with an increase of the total chain saw operating time, while the prevalence of pain in the hands or motility disturbance in the elbow joints showed a tendency to become greater as total operating time increased. Hydroxyproline/creatinine ratio in the group with over 9000 hours' experience was significantly higher than that in the group with under 3000 hours (p less than 0.05). By comparison with controls, the ratio in the group with over 3000 hours was significantly higher at the 5% level. (3) Hydroxyproline/creatinine ratio in the group with pain in the hands or with motility disturbance in the elbow joints was significantly higher than that in the group without them (p less than 0.05). (4) Hydroxyproline/creatinine ratio was inversely correlated with grip and pinch strength in operators ranging in age from 40 to 49 (p less than 0.01). (5) All individual ratios for operators with lower grip strength showed a higher increment than the mean values obtained from controls. These results indicate that increased urinary hydroxyproline excretion in chain saw operators may occur in association with damage to the musculoskeletal system caused by the prolonged use of vibrating tools.

Case report and study of collagen metabolism in Marfan's syndrome

The case report on a 33 year old woman with prominent features of Marfan's syndrome is presented. Characteristic signs were seen in the bones, the eyes, the cardiovascular system, and the lungs. Due to regurgitation of both the aortic and mitral valves and an aneurysm of the ascending aorta a double valve replacement was made, including a prosthesis of the aorta. The problems of early diagnosis and therapy of the life-threatening cardiovascular complications are discussed. Tissue specimens from the aorta were analysed histochemically and biochemically. Histology showed a typical necrosis of the media with cyst formation. Biochemical analysis by in vitro labeling of collagen in tissue explants and by electron microscopical evaluation showed proportions of type I and type III collagen which were significantly different from controls. In both the media and the adventitia the amount of type I collagen was drastically reduced as shown by quantitation of collagen and procollagen. Fibroblasts derived from the skin of the patient showed a normal content of type I and type III collagen. It is conceivable that the reduced content of type I collagen in the aortic wall is responsible for the weakness of the vessel wall causing formation of aneurysm and its sequelae.

Chronic treatment of Paget's disease of bone with synthetic human calcitonin

Twelve patients with Paget's disease of bone were treated with synthetic human calcitonin for seven to 26 months (mean 15.3 months). This group included six patients who had previous therapy. Eleven of the 12 patients experienced relief of the symptoms associated with Paget's disease. The initial therapy of synthetic human calcitonin 0.5-1.0 mg subcutaneously was administered daily until the alkaline phosphatase had declined to a plateau response; the dose was then decreased to thrice weekly. The major biochemical findings were a 47 percent fall in serum alkaline phosphatase and a comparable decline in 24-hour urinary hydroxyproline. Two subjects discontinued therapy because of side effects; persistent nausea and vomiting in one and a cutaneous allergic reaction in the other. Other side effects were minor. Preliminary results suggest that some patients will maintain the same biochemical response on the reduced dose but that this is not predictable by pre-treatment data. We conclude that synthetic human calcitonin is a safe and effective treatment for Paget's disease of bone. Preliminary results suggest that the dose and frequency of administration of this agent must be individualized.

Biological variation in free serum hydroxyproline concentration

Improvements in the accuracy of single estimations of biochemical constituents such as the serum free hydroxyproline (FSHP) concentration can only result from control of biological variation as well as analytical variation. In this context two experiments were carried out to determine whether a significant diurnal rhythm in FSHP concentration exists in man, and whether a worthwhile reduction in intra-individual variance can be achieved by eliminating dietary sources of hydroxyproline. A significant (p < 0.001) diurnal variation in FSHP concentration was detected in a group of normal subjects, with a range of about 20% of the mean. In a second group of eight normal subjects, there was a substantial reduction in the within-subject variation after the start of dietary control. For the most precise determination of FSHP concentration therefore, dietary hydroxyproline sources must be controlled, preferably eliminated, and blood should be sampled at a standardised time of day.

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.

Urinary hydroxyproline excretion in carcinoma of the prostate. A comparison of 4 different modes of assessment and its role as a marker

Urinary hydroxyproline (HP) excretion has been estimated without prior dietary restriction in 33 patients with carcinoma of the prostate and expressed as either 24-h HP output or as the hydroxyproline/creatinine (HP/Cr) ratio in 24-h urine sample, an early morning urine sample or a spot urine sample. The early morning urine hydroxyproline/creatinine ratio (EMU HP/Cr) appears to be the most accurate and avoids the disadvantages of formal dietary restriction and prolonged urine collection. The rest is useful in monitoring the responses to treatment of a patient with bony metastatic disease and relapse of a patient when his tumour ceases to be hormone sensitive. Furthermore, changes in EMU HP/Cr occur earlier than changes in other clinical or investigative variables, giving the test predictive value.

Effect of varying energy and protein intake on nitrogen balance in adults engaged in heavy manual labour

1. The effect of varying energy and protein intake on nitrogen balance in adult men engaged in heavy manual labour was investigated. 2. Low protein and energy levels resulted in negative N balance and urea index (Waterlow, 1963) was decreased. 3. Urinary excretion of hydroxyproline was found to be sensitive to dietary protein level, but not to energy.

Amino acid and peptide absorption from partial digests of proteins in isolated rat small intestine

1. Absorption of each of sixteen amino acids, free and peptide-bound, has been measured in isolated rat small intestine perfused with five partial digests of proteins. 2. At low concentrations net absorption of each amino acid was proportional to its luminal concentration and independent of the nature of the amino acid. 3. A series of first-order multiple regressions was found to describe well the characteristics of absorption. 4. Rate constants for disappearance of free and peptide-bound amino acids from the lumen were closely similar. However, substantial back-flux occurred of amino acids derived from peptide hydrolysis. Hence 60-70% of the amino-N entering the serosal tissue fluid probably had left the lumen as free amino acids. 5. Intact peptides crossed the mucosa during absorption from a soy bean hydrolysate and in substantial quantities during absorption from one casein digest but not from another. With other hydrolysates there was no evidence for passage of peptides to the serosa. 6. In several cases there was a serious discrepancy between the amount of amino-N absorbed from the lumen and the amount accounted for as peptide or free amino acid in the serosal secretion. 7. The characteristics of absorption were similar (apart from the exceptions in 5 above) for all the digests studied except for soy bean hydrolysate.

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.