Large performance variation does not affect outcome in the Finnish cervical cancer screening programme.

OBJECTIVE: Cytology screening for prevention of cervical cancer can reduce incidence and mortality by more than 80% in settings with good organization and rigorous quality control. Audit studies are essential for reaching and maintaining a high quality of screening. The aim of this study was to evaluate variation in performance indicators by screening laboratory and assess the impact on the effectiveness of screening as indicated by cervical intraepithelial neoplasia grade 3 and above (CIN3+) rates after a negative screen. METHODS: Seven cytology screening laboratories operating during 1990-1999 with a total of 953 610 screening tests performed were included in the study. By linking screening and cancer register files, all cases of CIN3+ diagnosed in the screened population were identified. For 395 CIN3+ cases with a preceding negative screen and 787 controls, a re-evaluation of smears was undertaken to uncover false negative screening tests. Performance parameters and rates of CIN3+ after a negative screen were analysed for interlaboratory heterogeneity. RESULTS: The rates of follow-up recommendations and referrals varied by up to 3.6- (2.8-10.2%) and 4.0-fold (0.03-0.12%), respectively. CIN1, CIN2 and CIN3+ screen detection rates differed by up to 8.5- (0.02-0.17%), 5.4- (0.05-0.25%) and 3.3-fold (0.05-0.18%). False negative rates determined by re-evaluation showed up to 2.1-fold differences (29-62%). Rates of CIN3+ after a negative screen (0.023-0.048%) and as a proportion of total CIN3+ (15-31%) in the screened population were low and did not vary significantly. CONCLUSIONS: There were large variations in the sensitivity-specificity trade-off between laboratories, reflected in all performance indicators as well as in the test validity estimates of the re-evaluation phase, but not in screening effectiveness. Even though performance variations do not always have an impact on the effectiveness of screening, they lead to variations in cost, treatment and psychological burden, and should be addressed.

Involvement of the subacromial bursa in impingement syndrome of the shoulder as judged by expression of tenascin-C and histopathology.

Our aim was to evaluate bursal involvement at different stages of the impingement syndrome as judged by conventional histopathological examination and expression of tenascin-C, which is known to reflect active reparative processes in different tissues and disorders. Samples of subacromial bursa were taken from 33 patients with tendinitis, 11 with a partial tear and 18 with a complete tear of the rotator cuff, and from 24 control shoulders. We assessed the expression of tenascin-C, the thickness of the bursa, and the occurrence and degree of fibrosis, vascularity, haemorrhage and inflammatory cells. The expression of tenascin-C was significantly more pronounced in the complete tear group (p < 0.001) than in the partial tear, tendinitis or control groups. It was more pronounced in the tendinitis group than in the control group (p = 0.06), and there was more fibrosis in all the study groups than in the control group. The changes in the other parameters were not equally distinctive. Expression of tenascin-C did not correlate with the conventional histopathological parameters, suggesting that these markers reflect different phases of the bursal reaction. Tenascin-C seems to be a general indicator of bursal reaction, being especially pronounced at the more advanced stages of impingement and this reaction seems to be an essential part of the pathology of impingement at all its stages.

Assays for acetaldehyde-derived adducts in blood proteins based on antibodies against acetaldehyde/lipoprotein condensates.

BACKGROUND: Acetaldehyde-derived protein condensates (adducts) have been suggested as promising biological markers of alcohol abuse because they represent actual metabolites of ethanol. However, the detection of such condensates in vivo has been hampered by a lack of sensitive and specific methods. METHODS: To develop new approaches for the detection of acetaldehyde adducts, we have raised antibodies against condensates with acetaldehyde and lipoproteins, which have previously been shown to be readily modified by acetaldehyde in vitro. The characteristics of these antibodies were compared with those raised against bovine serum albumin/acetaldehyde adduct and against other types of lipoprotein modifications, as induced by malondialdehyde, oxidation, and acetylation. RESULTS: The antibodies raised against low-density lipoprotein (LDL)/acetaldehyde, very low density lipoprotein (VLDL)/acetaldehyde, and bovine serum albumin/acetaldehyde all reacted with protein adducts generated at physiologically relevant concentrations of acetaldehyde in vitro, whereas the antibodies raised against malondialdehyde/LDL, oxidized LDL, or acetylated LDL were not found to cross-react with the acetaldehyde-derived adducts. In assays for acetaldehyde adducts from erythrocyte and serum proteins of patients with excessive ethanol consumption (n = 32) and healthy control individuals (n = 22), the antibody prepared against the acetaldehyde/VLDL condensate was found to provide the most effective detection of acetaldehyde adducts in vivo. CONCLUSIONS: Current data indicate that acetaldehyde generates immunogenic adducts with lipoproteins in vivo. Antibodies raised against the VLDL/acetaldehyde may provide a basis for new diagnostic assays to examine excessive alcohol consumption.

Aminoterminal propeptide of the alpha1-homotrimer variant of human type I procollagen (hotPINP) in malignant pleural effusion.

The aminoterminal propeptide (hotPINP) of type I homotrimer, a putative malignancy-associated type I collagen variant, was purified for the first time and a method was established for its detection in pleural fluid. Samples of 58 patients, with malignant or benign disease, were studied with specific immunoassays for the two propeptides of type-I procollagen (PICP and PINP) and with HPLC-DEAE chromatography to separate the two PINP variants. HotPINP was present in 64% of both benign and malignant pleural effusion fluids, with the exception of malignant mesotheliomas, none of which showed the presence of hotPINP. Also the PICP to PINP ratios were lower than normal in both benign and malignant samples (altogether in 69% of samples), although this deviation was greater in malignancy. These two phenomena were independent of each other. As synthesis of the alpha1-homotrimer-variant of type-I collagen seems to be relatively common during the formation of pleural effusion, it may be generally related to a fibroproliferative reaction in the pleural wall.

Acetaldehyde adducts in blood and bone marrow of patients with ethanol-induced erythrocyte abnormalities.

BACKGROUND: Although alcohol abuse is known to cause a wide array of adverse effects on blood cell formation, the molecular mechanisms by which alcohol exerts its toxic actions remain poorly defined. We examine here the formation of acetaldehyde-derived protein modifications in erythrocytes and in their bone marrow precursors using antibodies specifically recognizing acetaldehyde-modified epitopes in proteins independently of the nature of the carrier protein. MATERIALS AND METHODS: We studied 138 consecutive adult patients undergoing bone marrow aspiration due to macrocytosis (MCV values above 99 fL). Assessment included complete blood counts, morphologic review, assessment of alcohol consumption, and biochemical and immunocytochemical assays for acetaldehyde adducts. RESULTS: There were 68 patients (49%) with a history of excessive alcohol consumption, 28 (20%) of whom were patients with severe dependence. The blood smears prepared from the alcoholic patients with macrocytosis also contained stomatocytes and knizocytes. Bone marrow aspirates from 12 alcoholic patients showed vacuolization of pronormoblasts and the presence of ring sideroblasts was noted in 8 cases. In immunocytochemical analyses of the peripheral blood erythrocytes, acetaldehyde-derived epitopes were found to occur both on the cell membrane and inside the erythrocytes. Bone marrow aspirates also showed positive staining for acetaldehyde adducts in the erythropoietic cells in 8 of 11 (73%) consecutive alcoholic patients. Separation of the erythrocyte proteins from the samples of alcoholics on HPLC-chromatography revealed the formation of fast-eluting hemoglobin fractions, which also reacted with antibodies against acetaldehyde adducts. CONCLUSIONS: Current data suggest that acetaldehyde-erythrocyte adducts are formed in vivo in blood and bone marrow of patients with excessive alcohol consumption. This may contribute to the generation of the erythrocyte abnormalities, which are frequently observed in alcoholic patients.

Increased amount of type III pN-collagen in human abdominal aortic aneurysms: evidence for impaired type III collagen fibrillogenesis.

PURPOSE: This study aimed to characterize the distribution of structural domains of type I and III collagens in the wall of abdominal aortic aneurysms (AAAs), by the use of undilated atherosclerotic aortas (aortoiliac occlusive disease [AOD]) and healthy abdominal aortas as controls. METHODS: Immunohistochemical staining was applied with antibodies for the aminoterminal propeptides of type I (PINP) and type III (PIIINP) procollagens, which represent newly synthesized type I and III pN-collagens. In addition, an antibody against the aminoterminal telopeptide of type III collagen (IIINTP) was used as a means of detecting maturely cross-linked type III collagen fibrils. RESULTS: The newly synthesized type III procollagen detected by means of PIIINP staining was concentrated in the media in aneurysmal aortas, whereas type I pN-collagen was localized in the intima in both AAAs and AODs. The healthy aortas showed no immunoreactivity for either PIIINP or PINP. The cross-linked type III collagen, detected by means of IIINTP staining, stained transmurally in all study groups, but appeared more abundant in the media in AAAs. CONCLUSION: Our results strongly suggest that the metabolism of type III collagen is enhanced in AAAs. Intensive type III pN-collagen staining was present mainly in the media layer in AAAs, suggesting a role of type III collagen in aneurysm formation, whereas type I pN-collagen was present in the intima in both AAAs and AODs, suggesting that type I collagen synthesis is a fibroproliferative response related to the atherosclerotic process. The increased type III pN-collagen in AAAs may result in impaired fibril formation and, thus, in decreased tensile strength of aneurysmal tissue.

Characterization of a hyaluronan receptor on rat sinusoidal liver endothelial cells and its functional relationship to scavenger receptors.

Hyaluronan is a widely distributed extracellular component of connective tissue with several mechanical and cell biological functions. The serum level of hyaluronan is elevated in rheumatic and liver diseases and in certain malignancies. The major route of hyaluronan clearance from the blood is via the liver, taken up predominantly by sinusoidal liver endothelial cells. We have purified a novel hyaluronan binding protein from liver that also has an affinity for the N-terminal propeptide of type I procollagen, a physiological scavenger receptor ligand. A polyclonal antibody raised against the protein was found to inhibit the binding and degradation of hyaluronan as well as two scavenger receptor ligands by cultured sinusoidal liver endothelial cells. Immunostaining of nonpermeabilized liver cells and liver sections showed that the antibody specifically stains the surface of sinusoidal liver endothelial cells. After pretreatment with monensin to block the recirculation of endocytic receptors, the immunostaining was specifically associated with early endosomes of these cells. Thus, this rat sinusoidal liver endothelial cell hyaluronan receptor shares functional properties with the scavenger receptor family, a group of proteins shown to play a key role in the uptake of atherogenic lipids and other waste products from the tissues.

Scavenger-receptor-mediated endocytosis in endocardial endothelial cells of Atlantic cod Gadus morhua.

Scavenger receptors are multifunctional integral membrane proteins that mediate the endocytosis of many different macromolecular polyanions and also participate in host defence reactions and cell adherance. In Atlantic cod (Gadus morhua L.), two intravenously injected scavenger receptor ligands, [125I]tyramine-cellobiose-labelled formaldehyde-treated serum albumin (125I-TC-FSA) and 125I-labelled N-terminal propeptide of type I procollagen (125I-PINP), distributed mainly to the heart. Cellular uptake was visualized by injections of fluorescently labelled FSA (FITC-FSA), which was recovered in discrete vesicles in endocardial endothelial cells of both heart chambers. Studies in vitro showed that radioiodinated FSA and PINP were endocytosed and degraded very efficiently by cultured atrial endocardial endothelial cells. Moreover, uptake of 125I-FSA was Ca2+-independent. Out of a range of unlabelled ligands, only the scavenger receptor ligands FITC-FSA, polyinosinic acid and, to a varying extent, FSA, acetylated low-density lipoprotein (AcLDL) and PINP, were able to compete with radioiodinated FSA, PINP or AcLDL for uptake in isolated endocardial cells. From our findings, we conclude that the endocardial endothelial cells are major carriers of scavenger receptors in cod. In addition, our results strengthen the hypothesis that these cells in cod play the same important function as that established for the scavenger endothelial cells of the mammalian liver.

Insulin enhances macrophage scavenger receptor-mediated endocytic uptake of advanced glycation end products.

Hyperglycemia accelerates the formation and accumulation of advanced glycation end products (AGE) in plasma and tissue, which may cause diabetic vascular complications. We recently reported that scavenger receptors expressed by liver endothelial cells (LECs) dominantly mediate the endocytic uptake of AGE proteins from plasma, suggesting its potential role as an eliminating system for AGE proteins in vivo (Smedsrod, B., Melkko, J., Araki, N., Sano, H., and Horiuchi, S. (1997) Biochem. J. 322, 567-573). In the present study we examined the effects of insulin on macrophage scavenger receptor (MSR)-mediated endocytic uptake of AGE proteins. LECs expressing MSR showed an insulin-sensitive increase of endocytic uptake of AGE-bovine serum albumin (AGE-BSA). Next, RAW 264.7 cells expressing a high amount of MSR were overexpressed with human insulin receptor (HIR). Insulin caused a 3.7-fold increase in endocytic uptake of 125I-AGE-BSA by these cells. The effect of insulin was inhibited by wortmannin, a phosphatidylinositol-3-OH kinase (PI3 kinase) inhibitor. To examine at a molecular level the relationship between insulin signal and MSR function, Chinese hamster ovary (CHO) cells expressing a negligible level of MSR were cotransfected with both MSR and HIR. Insulin caused a 1.7-fold increase in the endocytic degradation of 125I-AGE-BSA by these cells, the effect of which was also inhibited by wortmannin and LY294002, another PI3 kinase inhibitor. Transfection of CHO cells overexpressing MSR with two HIR mutants, a kinase-deficient mutant, and another lacking the binding site for insulin receptor substrates (IRS) resulted in disappearance of the stimulatory effect of insulin on endocytic uptake of AGE proteins. The present results indicate that insulin may accelerate MSR-mediated endocytic uptake of AGE proteins through an IRS/PI3 kinase pathway.

Advanced glycation end products are eliminated by scavenger-receptor-mediated endocytosis in hepatic sinusoidal Kupffer and endothelial cells.

Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGE). Physiological aspects of the catabolism of non-enzymically glycated proteins were studied in vivo and in vitro. AGE-modified BSA (AGE-BSA) was a mixture of high-Mr (cross-linked), monomeric and low-Mr (fragmented) AGE-BSA. After intravenous administration in rat, all three fractions of AGE-BSA accumulated extremely rapidly and almost exclusively in liver. Uptake in liver endothelial, Kupffer and parenchymal cells accounted for approx. 60%, 25% and 10-15% respectively of hepatic elimination. Both cross-linked and monomeric AGE-BSA were efficiently taken up and degraded in cultures of purified liver endothelial and Kupffer cells. Endocytosis of AGE-BSA by these cells was inhibited by several ligands for the scavenger receptor. Although 125I-Hb was not endocytosed in vitro, 125I-AGE-Hb was effectively endocytosed by a mechanism that was subject to inhibition by AGE-BSA. Endocytosis of N-terminal propeptide of type I procollagen, a physiological ligand for the scavenger receptor, was effectively inhibited by AGE-Hb and AGE-BSA. We conclude that AGE-modification renders macromolecules susceptible for elimination via the scavenger receptor of both liver endothelial and Kupffer cells.

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.

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.

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.

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.

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.

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.

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)

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.

Thrombolytic therapy with streptokinase stimulates collagen breakdown.

BACKGROUND: Plasmin is capable of degrading extracellular matrix components such as collagen in vitro. To evaluate the significance of this for in vivo conditions, we set out to study the effect of streptokinase, which acts by converting plasminogen to plasmin, on the serum concentrations of the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal propeptide of type I procollagen (PICP). METHODS AND RESULTS: Twenty-three patients with suspected acute myocardial infarction were included in the study; 17 of them received thrombolytic therapy, and six were treated conservatively. PIIINP and PICP were assayed with radioimmunoassays. Kinetics of creatine kinase-MB release were determined to differentiate reperfusers from nonreperfusers. Composite curves of creatine kinase-MB release were constructed for different patient subgroups. During streptokinase infusion the serum concentrations of PIIINP increased rapidly, with a maximum mean increase of 50% (from 2.2 +/- 0.2 to 3.3 +/- 0.3 micrograms/l) in 45 minutes. A similar increase was also observed in two patients who received thrombolytic therapy but did not subsequently develop any myocardial infarction determined on the basis of enzyme release. The relative increase in PIIINP during streptokinase treatment was higher in those acute myocardial infarction patients with probable reperfusion than those with nonprobable reperfusion. Corresponding changes in PIIINP were not seen in the control group. Two days later there was a second increase in serum PIIINP for both patient groups. This change coincided with a similar increase in PICP. CONCLUSIONS: We conclude that streptokinase, probably by activation of plasminogen to plasmin, stimulates the breakdown of type III collagen during thrombolytic therapy. This phenomenon may decrease the risk of rethrombosis of the affected artery if the exposed collagen is responsible for thrombosis formation, but it could also be involved in the development of hemorrhagic complications during thrombolytic therapy. The second increase in PIIINP levels probably indicates type III collagen synthesis of the infarcted area. This investigation represents a pilot study, and more studies on the effects of various thrombolytic agents on interstitial collagen metabolism are obviously needed.