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J Melkko

Publications and source records attributed to J Melkko.

14 recordsLinked to original sources
PubMed1996

Immunoassay for intact amino-terminal propeptide of human type I procollagen.

We have developed quantitative immunoassays for the intact, trimeric amino-terminal propeptide of human type I procollagen (PINP) and its Col1 domain. Intact PINP was isolated from the pleural fluids of cancer patients by a combination of ion-exchange, gel-filtration, and reversed-phase chromatographies. The amino-terminal Col1 domain of PINP was isolated after bacterial collagenase treatment of the heat-denatured trimeric propeptide. For the intact PINP assay we used a polyclonal antibody with only 1.2% cross-reaction with the monomeric Col1 domain. In human serum, this assay detects only one peak of PINP antigenicity that has the size of known intact PINP. Under similar conditions, an assay for the Coll domain of PINP recognized two circulating antigens. The biological relevance was further verified in wound fluid. Interassay and intraassay CVs were 3.1-9.3% for values within the reference intervals (mean +/- 2SD) for intact PINP in serum, which were 19-84 microg/L for women and 20-76 microg/L for men.

Adult↗
PubMed1995

Responses of type I and type III collagen synthesis after replacement of the hip joint.

Liberation of the carboxy-terminal propeptide of type I procollagen (PICP) and the amino-terminal propeptide of type III procollagen (PIIINP) into body fluids reflects synthesis of the respective collagen types. Here, we followed PICP and PIIINP in serum with specific radioimmunoassays after hip surgery. Preoperative median of S-PICP was 112 micrograms/liter (range 87 to 154, n = 9), the 1-day median being 58 micrograms/liter (33 to 79). The corresponding medians for S-PIIINP were 4.4 micrograms/liter (3.5 to 7.0) and 3.3 micrograms/liter (2.0 to 3.5). The medians reached their maximums 14 days after surgery, 172 micrograms/liter (122 to 440) for S-PICP and 12.4 micrograms/liter (8.0 to 15.4) for S-PIIINP, after which the preoperative values were slowly approached over several months. Comparable results were found in a greater sample (n = 50). Our results indicate that the synthesis of structural collagen is inhibited immediately after surgery, but the inhibition is soon overcome by active collagen synthesis at the site of trauma. Collagen metabolism remains activated for several months after surgery.

Collagen↗
PubMed1994

Clearance of NH2-terminal propeptides of types I and III procollagen is a physiological function of the scavenger receptor in liver endothelial cells.

This study was undertaken to determine the fate of circulating NH2-terminal propeptide of type I procollagen (PINP) in rats. Radiolabeled PINP showed a biphasic serum decay curve after intravenous injection. 79% of the material disappeared from the blood during the initial alpha-phase (t1/2 alpha = 0.6 min), while the remaining 21% was eliminated with a t1/2 beta of 3.3 min. The major site of uptake was the liver, 78, 1, and 21% of its radioactivity being recovered in isolated liver endothelial cells (LEC), Kupffer cells, and parenchymal cells, respectively. In LEC, fluorescently labeled PINP accumulated in small (0.1 microns) peripheral and larger (> 0.1 microns) perinuclear vesicles within 10 min at 37 degrees C after a binding pulse at 4 degrees C. These grew in size with increasing chasing time, reaching a maximum diameter of 1 microns or more after 30 min, and taking the shape of rings that were stained only along their periphery. At chase intervals exceeding 30 min, the size of the vesicles decreased, and after 60 min the stain appeared in smaller, densely stained perinuclearly located vesicles. Degradation of 125I-PINP to free smaller fragments and 125I- was significant after 30 min. Only formaldehyde-treated albumin, acetylated LDL, polyinosinic acid and NH2-terminal propeptide of type III procollagen (PIIINP) competed with PINP for uptake. These findings indicate that clearance of PINP and PIIINP, which are normal waste products generated in large quantities, is a physiological function of the scavenger receptor in LEC.

Animals↗
PubMed1994

Differential processing of type I and type III procollagens in the tumour cysts and peritoneal ascitic fluid of patients with benign and malignant ovarian tumours.

Progressive ovarian carcinoma induces the synthesis of type I and type III procollagens both in the tumour tissue and in the peritoneal cavity. We studied the processing of these proteins by determining the different antigen forms related to their propeptide parts by gel filtration and subsequent immunological assays. Samples of ovarian cyst fluid and peritoneal ascitic fluid were obtained from patients with benign and malignant ovarian tumours. In both benign and malignant ovarian cysts, the predominant procollagen antigens were the free propeptides, with few or no larger components, indicating efficient processing of types I and III procollagens in the tumour tissue. In ascitic fluid the processing was more variable. The aminoterminus of type III procollagen was partially unprocessed in all samples studied, whereas that of type I procollagen was nearly always completely processed. There was a clear difference between malignant and benign tumours in the processing of the carboxyterminus of type I procollagen: a significant part of the carboxyterminal propeptide antigen was invariably associated with a collagenous domain in malignant tumours, whereas in benign tumours the free propeptide predominanted. The results indicate that interstitial procollagens are effectively processed in the tumour tissue during the fibroproliferative reaction typical of malignant ovarian tumours, whereas the processing of the procollagens released into peritoneal ascitic fluid is incomplete.

Ascitic Fluid↗
PubMed1994

Systemic glucocorticoids decrease the synthesis of type I and type III collagen in human skin in vivo, whereas isotretinoin treatment has little effect.

The effects of systemic glucocorticoid and isotretinoin treatments on type I and type III collagen synthesis in intact skin were investigated by measuring the carboxyterminal and aminoterminal propeptides of type I procollagen, and the aminoterminal propeptide of type III procollagen, in suction blister fluid (SBF), in a study of 27 patients. All three parameters were significantly lower in the SBF of glucocorticoid-treated patients than in controls or patients undergoing treatment with isotretinoin, whereas the latter two groups did not differ significantly from each other. During glucocorticoid treatment, the concentrations of the procollagen propeptides were only about 20% of the corresponding control values, indicating that systemic therapy with prednisone at a dose of 0.48 mg/kg per day almost totally abolishes collagen synthesis in the skin. These results indicate that systemic glucocorticoid treatment suppresses the synthesis of both type I and type III collagen in the dermis, and suggest that many side-effects of these drugs, such as atrophy of the skin, are due to this inhibition. Systemic isotretinoin treatment did not stimulate skin collagen synthesis. Thus, its regenerative effect on connective tissue may be mediated by mechanisms other than direct stimulation of collagen synthesis.

Adult↗
PubMed1993

Procollagen synthesis and extracellular matrix deposition in MG-63 osteosarcoma cells.

We compared the procollagen synthetic properties of MG-63 osteosarcoma cells with those of cultured human skin fibroblasts. In both cells, the expressions of type I and III procollagens are largely dependent on the constant presence of ascorbate and coordinately decreased by the neutral polymer dextran T-40. The amino-terminal propeptides of pro-alpha 1 and pro-alpha 2 chains of type I procollagen are phosphorylated and those of the pro-alpha 1 and pN-alpha 1 chains of type III procollagen both phosphorylated and sulfated, there being no difference in net charge in the propeptides between these cell types. The major differences between MG-63 and normal fibroblasts are the exceptionally high relative synthesis of type III procollagen by MG-63 cells, up to about 40% of the total of types I and III (6% in cultured skin fibroblasts), and the inability of ascorbate-supplemented MG-63 cells to deposit collagens into an insoluble pericellular matrix. A longer dextran treatment shifts up to one-fourth of the proline-labeled extracellular macromolecules into the matrix fraction within 4 days (in control 4%). Despite processing of the procollagens to the respective collagens in the matrix, neither control matrices nor those induced by dextran induced increased production of alkaline phosphatase. In cultures up to 4 days postconfluence the proportion of type III collagen produced tended to increase over that in early confluent cultures. With respect to collagen production, the MG-63 cell line is not a representative of the osteoblast lineage but rather resembles a proliferative wound fibroblast.

Ascorbic Acid↗
PubMed1992

Connective tissue response to major surgery and postoperative infection.

Type I and type III collagen are components of a healing wound, and major structural proteins. According to our previous study, wound fluid concentrations of the liberated propeptide extensions of procollagens can be used to monitor collagen synthesis in the wound. Serum concentrations of the carboxyterminal propeptide of type I procollagen (PICP), and the aminoterminal propeptide of type III procollagen (PIIINP) were studied here for up to half a year in 102 patients, admitted for major abdominal surgery. In a frequent follow-up (n = 9), one minimum and two maxima were found for S-PICP, occurring 1 day, 7 days, and 2 months after surgery, respectively. S-PIIINP had a minimum at 1 day and a peak at 10 days. Relative changes (follow-up result/pre-operative concentration) of the propeptides in 50 uncomplicated patients were compared. The 1-day minimum of S-PICP was 0.60 (SD 0.18), and that of S-PIIINP 0.89 (0.27), (P less than 0.0001, 95% CI for the mean difference 0.21 to 0.36). The 7-day peak of S-PICP was 1.4 (0.5), and that of S-PIIINP 2.5 (1.2), (P less than 0.0001, CI 0.81 to 1.42). The 2-month-peak of S-PICP was 1.6 (0.3), and at the same time the relative S-PIIINP was still 1.7 (0.3) without any separate peak. Major infectious (n = 8) and other (12) complications, exploratory procedures (22) and patients with abnormal pre-operative propeptide levels (8) were studied separately. Two early deaths were excluded. Only major infection had a remarkable effect on the responses of S-PICP (3/8) and S-PIIINP (5/8).(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen↗
PubMed1991

Effects of a combined estrogen-gestagen regimen on serum levels of the carboxy-terminal propeptide of human type I procollagen in osteoporosis.

Estrogen stimulates osteoblastic collagen production in vitro, but whether the same stimulation takes place in vivo is still unknown. To test the stimulatory effects of a combined estrogen-gestagen regimen in vivo we monitored serum levels of the carboxy-terminal propeptide of human type I procollagen (S-PICP) in a group of 12 osteoporotic women over a 150 week treatment period. Spinal bone mineral content (BMC) increased to a maximum of 5% over pretreatment values around week 90. Serum alkaline phosphatase (S-AP) and serum bone gla protein (S-BGP) both fell from initial values of 220 U/liter and 39 ng/ml, respectively, to 146 U/liter (p less than 0.01) and 27.2 ng/ml (NS) around week 60 and remained reduced over the remaining treatment period. S-PICP also fell from 117 to 68 micrograms/liter at week 60 and 70 micrograms/ml at week 150 (P less than 0.01). This is equal to a reduction to 32 +/- 10% pretreatment levels. The reduction in S-PICP was not significantly different from that of the other two markers of bone formation (S-AP and S-BGP). Thus, provided the metabolic clearance of PICP remains unaltered after hormone replacement therapy, no major stimulation of osteoblastic collagen type I synthesis was demonstrable during estrogen-gestagen treatment in this population of osteoporotic women. The changes in bone markers seen in this study are therefore consistent with an estrogen-mediated reduction in the frequency of remodeling activation. Because of the reduction in bone turnover and methodologic limitations of bone marker assays, however, smaller increases in the amount of bone formed per activation could remain undetectable.

Aged↗
PubMed1991

Use of a marker of collagen formation in osteoporosis studies.

Type I collagen accounts for most of the organic matrix of bones, but it is also an important constituent of soft connective tissue. Assessment of the turnover of such collagen is particularly relevant to bone metabolism. Determination of the carboxyterminal propeptide of type I procollagen (PICP) is a means of estimating the rate of type I collagen synthesis in the body. Serum concentrations of PICP have been shown to correlate with the rate of bone formation.

Adult↗
PubMed1991

The carboxy-terminal propeptide of type I procollagen in serum as a marker of bone formation: the effect of nandrolone decanoate and female sex hormones.

Seventy-nine osteoporotic (prior forearm or vertebral fracture), but otherwise healthy, postmenopausal women (aged 55 to 75 years) were allocated to two double-blind trials: (1) 39 women received either nandrolone decanoate (anabolic steroid) 50 mg as an intramuscular depot injection or a placebo injection every 3 weeks for 1 year; and (2) 40 women received either 2 mg 17 beta-estradiol plus 1 mg norethisterone acetate or placebo tablets daily for 1 year. Sixty-seven (85%) completed the 1 year of treatment. Serum concentration of type I procollagen carboxy-terminal propeptide (PICP) was measured before and at 3, 6, 9, and 12 months of therapy. In addition, 32 of the women had an iliac bone biopsy taken after double tetracycline labeling. Initial serum PICP correlated significantly with histomorphometrically measured rate of bone formation (r = .4; P less than .05) and plasma bone Gla protein (r = .6; P less than .001), but not with histomorphometrically measured bone resorption or biochemical estimates of bone resorption (fasting urinary hydroxyproline and calcium). Estrogen-progestogen therapy significantly decreased (P less than .001) serum PICP by about 30%, whereas anabolic steroid therapy hardly affected it. We conclude that serum PICP may be used as a noninvasive measurement of bone formation on a group basis. Whereas bone formation is clearly decreased during estrogen-progestogen therapy, it is not affected by long-term therapy with anabolic steroids.

Aged↗
PubMed1991

Synthesis of type I collagen in healing wounds in humans.

To quantify wound healing in surgical patients, samples of wound fluid were collected through a silicone rubber tube for 7 postoperative days and their concentrations of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were measured with specific radioimmunoassays. The mean concentration of PICP in would fluid on day 1 was 207 +/- 92 (SD) micrograms/L, and on day 2 908 +/- 469 micrograms/L (p less than 0.001, signed rank test). On day 7, the mean concentration reached was 380 times higher than that of day 1 (79,330 +/- 54,151 micrograms/L). Only one peak of PICP antigenicity, corresponding to the intact propeptide as set free during synthesis of type I procollagen, was detected on Sephacryl S-300 gel filtration analysis of wound fluid samples. The mean concentration of PIIINP was 70 +/- 61 micrograms/L on day 1, 86 +/- 88 micrograms/L on day 2, and 180 +/- 129 micrograms/L on day 3 (p less than 0.001 when compared with day 1). Finally on day 7, a 250-fold concentration (17,812 +/- 9839 micrograms/L), compared with day 1, was reached. Methods described in the present paper allow separate and repetitive quantification of the synthesis of both type I and type III procollagen during human wound healing.

Adult↗
PubMed1990

Circulating C-terminal propeptide of type I procollagen is cleared mainly via the mannose receptor in liver endothelial cells.

The fate of the circulating C-terminal propeptide of type I procollagen (PICP) was studied. Trace amounts of 125I-PICP administered intravenously to rats disappeared from the blood with an initial t1/2 of 6.1 min. After 45 min the radioactivity was distributed as follows: liver, 36%; blood, 23%; kidneys, 18%; urine, 20%; spleen, 1%; lungs, 2%; heart, 0.4%. To prevent escape of label from the site of uptake, PICP was labelled with 125I-tyramine cellobiose (125I-TC), which is trapped intralysosomally. With this ligand a serum t1/2 of 8.7 min was recorded, and 70% and 20% was traced in the liver and kidneys respectively. The uptake per liver endothelial cell (LEC) was 1000 times that per parenchymal cell and twice that per Kupffer cell. At 1 h and 6 h after addition of 125I-PICP to cultured LEC, 15% and 45% respectively, had been endocytosed. Only ligands for the mannose receptor could compete with PICP for endocytosis. To study whether the same specificity was operative in vivo, 125I-PICP was injected along with an excess of ovalbumin, which is known to be endocytosed by the mannose receptor of LEC. The serum t1/2 was prolonged from 6 to 16 min, signifying that terminal mannose residues are an important signal for clearance of PICP. In conclusion, these studies show that LEC constitute the main site of uptake of circulating PICP. The uptake is mediated by endocytic receptors which recognize terminal mannose residues.

Binding, Competitive↗
PubMed1990

Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen.

Type I collagen is the most abundant collagen type in soft tissues and the only type found in mineralized bone. We established a rapid equilibrium radioimmunoassay for the carboxyterminal propeptide of human type I procollagen (PICP), to be used as an indicator of the synthesis of type I collagen. We isolated type I procollagen from the medium of primary cultures of human skin fibroblasts, digested the protein with highly purified bacterial collagenase, and purified PICP by lectin-affinity chromatography, gel filtration, and ion-exchange separation on HPLC. The purity of the protein was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by N-terminal amino acid sequencing of its component chains. The final radioimmunoassay was established with polyclonal rabbit antibodies. Material antigenically related to PICP is readily detected in human serum. There is only one form of the serum antigen, its molecular size and affinity to the antibodies being similar to those of the isolated propeptide. Intra- and interassay CVs are 3% and 5%, respectively. Preliminary reference intervals for healthy adults (18 to 61 years of age) are 38-202 micrograms/L for men and 50-170 micrograms/L for women: in men the concentration is inversely related to age. The serum antigen is stable during storage and after repeated thawing.

Adolescent↗