Premila Trivedi

Serum Concentrations of the Type I and III Procollagen Propeptides as Biochemical Markers of Growth Velocity in Healthy Infants and Children and in Children with Growth Disorders

ABSTRACT: The reproducibility and specificity of a new, rapid, simple RIA for measuring the concentration of the soluble carboxypropeptide of type I procollagen (PICP) in serum was confirmed. Serum PICP was determined in 442 healthy Caucasian subjects ranging in age from 3 wk to 18 y. Highest PICP values (mean ± SD: 2200 ± 350 μg/L) occurred in infants less than 3 mo of age, falling by 70% at 2 y and by an additional 10% at 4 y. There was no significant change in serum PICP between 4 and 16 y of age (330 ± 130 μg/L), but a decrease to adult levels of <160 μg/L, occurred by 18 y. In 76 children with growth disorders, serum PICP was related to linear growth velocity (p < 0.001), although there were no significant differences in PICP among the 38 children with growth hormone insufficiency, the 21 short children with no endocrinologic abnormality, or the 17 tall children. All 15 prepubertal children treated with growth hormone for 3 mo showed significant increases in both growth velocity and serum PICP, with a significant relationship (p < 0.01) between the degree of increases. The rise in serum PICP at 3 mo (but not baseline PICP values) predicted the increase in growth velocity after 1 y of treatment. Similar changes were observed in the concentration of the aminopropeptide of type III procollagen, except that serum aminopropeptide of type III procollagen showed a definite increase during puberty and a wider spread of values in growth disorders. We conclude that measuring serum PICP by the new, reproducible assay reflects height velocity in prepubertal children and may be a useful biochemical means of monitoring growth rates.

Growth velocity, growth hormone therapy, and serum concentrations of the amino-terminal propeptide of type III procollagen

The relationship between serum concentrations of the amino-terminal propeptide of type III procollagen (PIIINP) and growth was assessed in 307 healthy subjects and 82 children with disorders of growth (41 with insufficient growth hormone, 23 with short stature and normal endocrinologic studies, 18 with tall stature) by means of a recently developed, simplified PIIINP radioimmunoassay. The PIIINP value appeared to be related to height velocity; in healthy children of each sex, the pattern of change with age mirrored the shape of the standard height velocity curve; in children with disorders of growth, there was a statistical correlation (p less than 0.001) between PIIINP concentration and height velocity. However, measurement of serum PIIINP alone had no diagnostic value because there was considerable overlap of PIIINP values in children with growth hormone insufficiency, short stature, normal stature, and tall stature. The most appropriate application of PIIINP may be in the monitoring of prepubertal children receiving exogenous growth hormone therapy; in these patients, increases in height velocity were reflected by increases in PIIINP, and early increases in PIIINP may have predictive value.

Collagen metabolism and growth in prepubertal children with asthma treated with inhaled steroids

OBJECTIVE To investigate growth and markers of collagen and bone metabolism in prepubertal children with asthma. STUDY DESIGN We measured growth velocity over 12 months and markers of collagen types I and III synthesis (PINP, PICP, PIIINP), collagen type I degradation (ICTP), and bone metabolism (bone-specific alkaline phosphatase and osteocalcin) on one occasion in 56 prepubertal children with stable asthma, 39 of whom were treated with inhaled budesonide or beclomethasone. Collagen data were compared with normal control values. RESULTS Children treated with inhaled steroids had reduced collagen synthesis (PINP, PIIINP) compared with control subjects (p = 0.038, p = 0.045), although PICP was increased (p = 0.05). Carboxyterminal telopeptide of type I collagen was reduced in patients treated with inhaled steroids (p < 0.0005) compared with nonsteroid-treated patients. Serum osteocalcin but not bone-specific alkaline phosphatase was significantly reduced in children treated with inhaled steroids (p < 0.02). Significant correlation was observed between PIIINP and ICTP and growth velocity. CONCLUSION Collagen turnover is reduced in children with asthma receiving long-term inhaled steroid treatment. Markers of collagen synthesis provide a more accurate reflection of growth disturbance than osteocalcin and bone-specific alkaline phosphatase.

Monitoring of veno-occlusive disease after bone marrow transplantation by serum aminopropeptide of type III procollagen

Differential diagnosis of hepatic complications after bone marrow transplantation (BMT) is often difficult. To assess whether serum concentrations of the aminopropeptide of type III procollagen (PIIINP) could facilitate diagnosis, we measured serum PIIINP, corrected for age by conversion to standard deviation scores (SDS), serially after BMT in 27 children. A preliminary study of 11 patients showed that a PNIIINP-SDS cutoff of 8.0 was an optimum for diagnosis of veno-occlusive disease (VOD). PIIINP-SDS was increased above cut-off 1-25 days before the onset of clinical signs in the 12 patients (4 from the preliminary group, the others from a group of 16 studied prospectively) who developed VOD, with subsequent changes in PIIINP-SDS mirroring the course of VOD. By contrast, PIIINP-SDS remained below cut-off in all other patients, including 7 with liver graft-versus-host disease and 3 with drug hepatotoxicity. PIIINP-SDS values greater than 8.0 predict, diagnose, and monitor VOD after BMT.

Prognostic value of serum hyaluronic acid and type I and III procollagen propeptides in extrahepatic biliary atresia.

Although portoenterostomy has greatly improved the prognosis of extrahepatic biliary atresia (EHBA), 10-20% of patients still die before 5 y of age, and the only treatment option is liver transplantation (LT). To investigate whether these patients may be identified at an early stage, when the chances of successful LT are optimal, we have measured serum concentrations of hyaluronic acid (HA), the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal and amino-terminal propeptides of type I procollagen (PICP, PINP) in 24 selected patients with EHBA, both before portoenterostomy and then every 6 mo until death (n = 10, age at death = 7-20 mo), LT (n= 6, age at LT = 1.1-4.8 y) or 5 y of age (n= 8). Raised serum HA above 200 μg/L before portoenterostomy identified those patients who would die or require LT in the first 5 y of life with a positive predictive value of 88%; after portoenterostomy, longitudinal changes in HA reflected clinical status in each patient. None of the other three markers was of prognostic value, and only PIIINP showed any relationship with clinical status, and then only up to 1.5 y. Interestingly, PINP (but not PICP) tended to be low in all patients before portoenterostomy and may reflect impaired bone collagen metabolism during early skeletal changes in EHBA. This study therefore suggests that measurement of serum HA may be a useful complementary test in EHBA, particularly in identifying, at an early stage, those patients who should be considered for LT.

Adaptative changes of metabolic zonation during the development of cirrhosis in growing rats

To evaluate changes in liver metabolic zonation during development of juvenile cirrhosis, zonal activities of succinate dehydrogenase, glutamate dehydrogenase, glucose-6-phosphatase, and nicotinamide adenine dinucleotide phosphate (NADPH) dehydrogenase were measured by quantitative cytochemistry in the liver of developing rats intoxicated with carbon tetrachloride and phenobarbitone. During treatment, activities were most decreased in perivenular zones and subsequently at the periphery of the cirrhotic nodules for succinate dehydrogenase and glucose-6-phosphatase, whereas glutamate dehydrogenase and NADPH dehydrogenase were less affected. In the periportal zones, enzyme activities decreased less. After stopping intoxication, the rats remained cirrhotic, but enzyme activities returned to control perivenular levels at the periphery of the cirrhotic nodule and to control periportal levels at its center. It is concluded that a metabolic zonation persists in carbontetrachloride/phenobarbitone-induced juvenile cirrhosis and that enzyme activities can recover despite persisting cirrhosis. In this model, afferent vessels seem to be located at the center of the cirrhotic nodules, and efferent vessels, at their periphery. A different metabolic zonation may exist in other human and animal liver cirrhosis that could be related to the site of initial liver damage.

The application of quantitative cytochemistry to study the acinar distribution of enzymatic activities in human liver biopsy sections

The zonal distribution of enzyme activities was measured by quantitative cytochemistry in cryosections of liver from three normal children and five infants with idiopathic hepatitis of infancy. Optimal conditions for cytochemical reactions were first validated in rat liver and subsequently used in human livers to quantify zonal activities of acid phosphatase (AP), succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), glucose-6-phosphatase (G6P) and NADPH-dehydrogenase (ND). In normal rat and human livers, activities were greater for SDH and G6P in periportal and for GDH and ND in perivenular hepatocytes, while AP was evenly distributed along the sinusoids. In five infants with idiopathic hepatitis of infancy (IHI), a similar trend of distribution was observed for the two mitochondrial (SDH and GDH) and the two microsomal (G6P and ND) enzymes, although the distribution gradient was less pronounced than, in normal livers. AP showed a mildly greater periportal than perivenular activity. This preliminary study shows that a similar metabolic zonation exists for these enzymes in human livers as is observed in rats.

Serum hyaluronic acid in healthy infants and children and its value as a marker of progressive hepatobiliary disease starting in infancy

We have established reference ranges for the concentrations of hyaluronic acid in serum from 397 infants and children and measured serum hyaluronic acid at presentation and 1 year follow-up in 37 infants who presented with hepatobiliary disease in the first 6 months of life. In health, hyaluronic acid concentrations fell progressively from median (10-90 percentile) values of 93 micrograms/l (49-153) at 1-3 months of age to 20 micrograms/l (9-40) at 2-3 years and 16 micrograms/l (6-32) at 4-18 years. In patients at presentation, the hyaluronic acid concentration was raised in 11 of 15 with biliary atresia, 6 of 11 with alpha-1 antitrypsin deficiency and 6 of 11 with cryptogenic hepatitis of infancy. One year later, the 9 patients who developed progressive liver disease showed 2-6-fold increases in hyaluronic acid concentration while no increase was observed in the 28 with undetectable or mild disease. Increases in serum hyaluronic acid concentration appeared to be a better indicator of progressive liver disease in infancy than standard laboratory tests.

Developmental changes in the intra-acinar distribution of succinate dehydrogenase, glutamate dehydrogenase, glucose-6-phosphatase, and NADPH dehydrogenase in the rat liver

Hepatocytes differ in their metabolism depending on their position in the liver acinus. To assess how such specialization changes during development, we used quantitative cytochemistry to measure succinate dehydrogenase (SDH), glutamate dehydrogenase (GDH), glucose-6-phosphatase (G6P), and NADPH dehydrogenase (ND) activities specifically in periportal and perivenular hepatocytes in developing rats, aged between 1-114 days. Important and distinct changes were observed in each zone for each enzyme during development. An intra-acinar gradient of distribution was present from day 1 for SDH and G6P and from day 5 for GDH and ND. It was being similar to the adult value for SDH but less pronounced for the remaining enzymes. The SDH and G6P activity was greater in periportal cells, and the GDH and ND activity was greater in perivenular cells. The more pronounced distribution with age was due, for G6P, to an initial specific periportal increase combined with a mild perivenular decrease and for GDH to a greater perivenular than periportal increase. The ND first increased simultaneously in both zones, but from day 20 the perivenular increase became prevalent. The SDH changes were parallel in both zones. All zonal enzyme activities changed distinctly after weaning. To what extent the changes in activities and metabolic zonation observed in our study reflect a response to specific metabolic demands of the liver or can be modified by environmental factors remains to be investigated.

Serum type III procollagen peptide as a non-invasive marker of liver damage during infancy and childhood in extrahepatic biliary atresia idiopathic hepatitis of infancy and α1 antitrypsin deficiency

To evaluate the role of serum procollagen III peptide as a non-invasive marker of liver damage and prognosis in hepatobiliary disorders of infancy, we have measured its concentration at presentation and serially in 30 infants with extrahepatic biliary atresia, 22 with idiopathic hepatitis of infancy, 10 with alpha 1 antitrypsin deficiency and 105 age-matched controls. Raised procollagen III peptide concentrations occurred in 51% of patients at presentation and 59% at follow up but were not related to the type of liver disease or the severity of liver damage, as assessed either by standard biochemical tests of liver function, serum glycocholic acid, semiquantitative assessment of 11 histopathological features or hepatic prolyl hydroxylase activity. Serum procollagen III peptide concentrations also gave no guide to prognosis. Although the factors determining serum procollagen III peptide concentrations in hepatobiliary disorders of infancy are unknown at the present time, we suggest that changes in growth rate may be of major importance in determining the significance of serum procollagen III peptide concentrations in infants and children.