Stool testing for pulmonary TB diagnosis in adults.

BACKGROUND: Mycobacterium tuberculosis is acid-fast and able to survive in the gastrointestinal tract. Thus, bacteria can be found in stool if sputum is swallowed. In this study, the accuracy of different diagnostic stool methods (microscopy, polymerase chain reaction PCR and culture) among adults with pulmonary TB (PTB) were assessed and compared with sputum culture.METHODS: Embase and PubMed were searched to identify studies with data on stool testing among patients with clinically presumed or microbiologically verified PTB.RESULTS: Thirteen relevant studies were included. A pooled sensitivity of one or more of the three TB identifying methods was 79.1% (95% CI 61.5-92.5). The sensitivity of stool microscopy, PCR and culture was respectively 41.1% (95%CI 24.9-58.2), 89.7% (95% CI 81.4-95.9) and 38.0% (95% CI 26.2-50.6). The heterogeneity of the studies included was high.CONCLUSION: Our review findings indicate that the analysis of stool specimens as part of PTB diagnostics is useful. PCR methods were particularly helpful in detecting a substantial proportion of patients with PTB.

Long-term effects of prenatal progesterone exposure: neurophysiological development and hospital admissions in twins up to 8 years of age.

OBJECTIVES: To perform a neurophysiological follow-up at 48 or 60 months of age in children exposed prenatally to progesterone compared with a placebo and evaluate their medical histories up to 8 years of age. METHODS: In this study, Danish participants of the PREDICT study, including 989 surviving children from 498 twin pregnancies, were followed-up. PREDICT was a placebo-controlled randomized clinical trial examining the effect of progesterone for prevention of preterm delivery in unselected twin pregnancies. Medical histories of the children were reviewed and neurophysiological development was evaluated by the parent-completed Ages and Stages Questionnaire (ASQ) at either 48 or 60 months after the estimated date of delivery. We used the method of generalized estimating equation to account for the correlation within twins. RESULTS: A total of 492 children had been exposed prenatally to progesterone and 497 to placebo. There was no difference in the number of admissions to or length of stay in hospital between the treatment groups, and we found no overall difference in the rates of diagnoses made. However, the odds ratios (ORs) for a diagnosis concerning the heart was 1.66 (95% CI, 0.81-3.37), favoring placebo, among all children, 2.38 (95% CI, 1.07-5.30) in dichorionic twins and 8.19 (95% CI, 1.02-65.6) in all children when excluding diagnoses made at outpatient clinic visits. ASQ scores were available for 437 children (progesterone, n = 225; placebo, n = 212). Mean ASQ score was slightly higher in the progesterone group compared with the placebo group (P = 0.03). In dichorionic twins, the risk of having a low ASQ score (< 10(th) centile) was decreased in the progesterone group (OR, 0.34 (95% CI, 0.14-0.86)). CONCLUSION: Second- and third-trimester exposure of the fetus to progesterone does not seem to have long-term harmful effects during childhood, but future studies should focus on cardiac disease in the child. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Integrin signalling regulates the expansion of neuroepithelial progenitors and neurogenesis via Wnt7a and Decorin.

Development of the cerebral cortex requires regulation of proliferation and differentiation of neural stem cells and a diverse range of progenitors. Recent work suggests a role for extracellular matrix (ECM) and the major family of ECM receptors, the integrins. Here we show that enhancing integrin beta-1 signalling, by expressing a constitutively active integrin beta-1 (CA*ß1) in the embryonic chick mesencephalon, enhances neurogenesis and increases the number of mitotic cells dividing away from the ventricular surface, analogous to sub-apical progenitors in mouse. Only non-integrin-expressing neighbouring cells (lacking CA*ß1) contributed to the increased neurogenesis. Transcriptome analysis reveals upregulation of Wnt7a within the CA*ß1 cells and upregulation of the ECM protein Decorin in the neighbouring non-expressing cells. Experiments using inhibitors in explant models and genetic knock-downs in vivo reveal an integrin-Wnt7a-Decorin pathway that promotes proliferation and differentiation of neuroepithelial cells, and identify Decorin as a novel neurogenic factor in the central nervous system.

Influence of chorionicity on perinatal outcome in a large cohort of Danish twin pregnancies.

OBJECTIVE: To assess outcome in twin pregnancies according to chorionicity. METHODS: A cohort was retrieved from local ultrasound databases at 14 obstetric departments in Denmark, comprising all twin pregnancies with two live fetuses scanned between weeks 11 and 14 in the period 1 January 2004 to 31 December 2006. Outcome data were retrieved from the National Board of Health. RESULTS: Among 2038 twin pregnancies, 1757 (86.2%) were dichorionic (DC) and 281 (13.8%) were monochorionic diamniotic (MC). In MC pregnancies, the rate of spontaneous fetal loss in both second and third trimesters was more than threefold higher than the comparable rate in DC pregnancies: 6.0% vs. 1.9% for at least one fetus in the second trimester (P < 0.001) and 2.1% vs. 0.7% in the third trimester (P = 0.03). In 98.4% of DC pregnancies and in 91.1% of MC pregnancies, at least one infant was liveborn. Amongst pregnancies with two live fetuses at 24 weeks, the proportion with two live infants at 28 days after delivery was 97.5% and 95.1%, respectively. CONCLUSIONS: The increased incidence of fetal loss in MC pregnancies compared with DC pregnancies predominantly occurs before 24 weeks' gestation. After this stage, although the risk of intrauterine fetal death is still higher in MC than in DC pregnancies, if both fetuses are alive at 24 weeks, the chance of a woman having two live infants 1 month after delivery is similar in MC and DC pregnancies.

Atmospheric chemistry of n-butanol: kinetics, mechanisms, and products of Cl atom and OH radical initiated oxidation in the presence and absence of NO(x).

Smog chamber/FTIR techniques were used to determine rate constants of k(Cl+n-butanol) = (2.21 +/- 0.38) x 10(-10) and k(OH+n-butanol) = (8.86 +/- 0.85) x 10(-12) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 296 +/- 2K. The sole primary product identified from the Cl atom initiated oxidation of n-butanol in the absence of NO was butyraldehyde (38 +/- 2%, molar yield). The primary products of the Cl atom initiated oxidation of n-butanol in the presence of NO were (molar yield) butyraldehyde (38 +/- 2%), propionaldehyde (23 +/- 3%), acetaldehyde (12 +/- 4%), and formaldehyde (33 +/- 3%). The substantially lower yields of propionaldehyde, acetaldehyde, and formaldehyde as primary products in experiments conducted in the absence of NO suggests that chemical activation is important in the atmospheric chemistry of CH(3)CH(2)CH(O)CH(2)OH and CH(3)CH(O)CH(2)CH(2)OH alkoxy radicals. The primary products of the OH radical initiated oxidation of n-butanol in the presence of NO were (molar yields) butyraldehyde (44 +/- 4%), propionaldehyde (19 +/- 2%), and acetaldehyde (12 +/- 3%). In all cases, the product yields were independent of oxygen concentration over the partial pressure range of 10-600 Torr. The yields of propionaldehyde, acetaldehyde, and formaldehyde quoted above were not corrected for secondary formation via oxidation of higher aldehydes and should be treated as upper limits. The reactions of Cl atoms and OH radicals with n-butanol proceed 38 +/- 2 and 44 +/- 4%, respectively, via attack on the alpha-position to give an alpha-hydroxy alkyl radical which reacts with O(2) to give butyraldehyde. The results are discussed with respect to the atmospheric chemistry of n-butanol.

Normal ICOS, ICOSL and AID alleles in Danish patients with common variable immunodeficiency.

Common variable immunodeficiency, CVID, is a primary antibody deficiency characterized by decreased levels of serum immunoglobulin G (IgG), decreased IgA and/or IgM and recurrent infections. It is assumed to be heterogeneous group of disorders caused by different genetic defects. Some patients have decreased levels of class switched memory B cells and/or decreased levels of somatic hypermutation which points to defects in the germinal centre (GC) reactions as cause of the disease in these patients. The inducible costimulator, ICOS, and its' ligand, ICOSL, are both involved in and necessary for the GC reaction and so is activation-induced cytidine deaminase, AID. Therefore, we sequenced the ICOS, ICOSL and AID genes in a cohort of 34 Danish CVID patients. We found 13 new single nucleotide polymorphisms (SNP) in the intron regions of the ICOSL gene as well as one SNP in exon 3. However, none of these polymorphisms were associated with CVID. We did not find a previously reported CVID-causing ICOS gene deletion or any other unique mutations in the ICOS or AID genes.

Short-term reproducibility of computed tomography-based lung density measurements in alpha-1 antitrypsin deficiency and smokers with emphysema.

PURPOSE: To study the short-term reproducibility of lung density measurements by multi-slice computed tomography (CT) using three different radiation doses and three reconstruction algorithms. MATERIAL AND METHODS: Twenty-five patients with smoker's emphysema and 25 patients with alpha1-antitrypsin deficiency underwent 3 scans at 2-week intervals. Low-dose protocol was applied, and images were reconstructed with bone, detail, and soft algorithms. Total lung volume (TLV), 15th percentile density (PD-15), and relative area at -910 Hounsfield units (RA-910) were obtained from the images using Pulmo-CMS software. Reproducibility of PD-15 and RA-910 and the influence of radiation dose, reconstruction algorithm, and type of emphysema were then analysed. RESULTS: The overall coefficient of variation of volume adjusted PD-15 for all combinations of radiation dose and reconstruction algorithm was 3.7%. The overall standard deviation of volume-adjusted RA-910 was 1.7% (corresponding to a coefficient of variation of 6.8%). Radiation dose, reconstruction algorithm, and type of emphysema had no significant influence on the reproducibility of PD-15 and RA-910. However, bone algorithm and very low radiation dose result in overestimation of the extent of emphysema. CONCLUSION: Lung density measurement by CT is a sensitive marker for quantitating both subtypes of emphysema. A CT-protocol with radiation dose down to 16 mAs and soft or detail reconstruction algorithm is recommended.

Volume adjustment of lung density by computed tomography scans in patients with emphysema.

PURPOSE: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. MATERIAL AND METHODS: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. RESULTS: The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. CONCLUSION: Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema.

Early clinical investigation of Viozan (sibenadet HCl), a novel D2 dopamine receptor, beta2-adrenoceptor agonist for the treatment of chronic obstructive pulmonary disease symptoms.

Viozan, (Sibenadet HCl, AR-C68397AA) is a dual D2 dopamine receptor, beta2-adrenoceptor agonist that combines bronchodilator activity with the sensory afferent modulating effects associated with D2-receptor agonism. Investigation in animal models of key chronic obstructive pulmonary disease (COPD) symptoms has demonstrated that sibenadet effectively inhibits sensory nerve activity, thereby reducing reflex cough, mucus production and tachypnoea. The results of the early clinical evaluation of this novel agent are reported. An initial proof of concept study (Study 1) aimed to determine the clinical potential of this novel agent by assessing the effects of three doses of sibenadet therapy relative to placebo, with two commonly used bronchodilators, intended to provide a benchmark against which sibenadet activity could be judged. In all, 701 patients were randomized to one of three sibenadet dose groups (400, 600 or 1000 microg ex valve), salbutamol 200 microg, ipratropium bromide (IB) 40 microg or placebo, all three times daily via pressurized metered dose inhaler (pMDI) for 4 weeks. Once the results of Study 1 had been evaluated, a dose-ranging, study (Study 2) involving 872 patients randomized to receive sibenadet (45, 270, or 495 microg ex actuator), or placebo all three times daily via pMDI, for 6 weeks commenced. Both studies were preceded by a 2-week baseline phase and followed by a 2-week follow up period.The primary efficacy variable identified changes in key COPD symptoms over the treatment period (compared with baseline data) as determined by the novel Breathlessness, Cough and Sputum Scale (BCSS). In addition, data on lung function, health-related quality of life and adverse events were collected. Patients receiving sibenadet therapy three times daily exhibited statistically significantly greater improvements in BCSS total score than those receiving placebo or bronchodilator therapy alone. A clear dose-response was evident in Study 2. Symptom improvement in this study was also accompanied by improved lung function and health-related quality of life. Sibenadet therapy was well tolerated with an adverse events profile comparable to current bronchodilator therapy. These data were viewed as extremely encouraging, warranting further, large-scale clinical investigation.

The role of the novel D2/beta2-agonist, Viozan (sibenadet HCl), in the treatment of symptoms of chronic obstructive pulmonary disease: results of a large-scale clinical investigation.

Viozan (sibenadet HCl, AR-C68397AA) is a novel dual D2 dopamine receptor, beta2-adrenoceptor agonist, developed specifically to treat the key symptoms of chronic obstructive pulmonary disease (COPD), breathlessness, cough and sputum. The dual sensory nerve modulation and bronchodilator effects of sibenadet have been demonstrated in initial dose-ranging studies of patients with COPD and large-scale clinical evaluation has now been completed. Sibenadet efficacy was determined by assessing symptomatic changes, as defined by the novel assessment tool, the Breathlessness, Cough and Sputum Scale (BCSS). The findings of two placebo-controlled studies are reported. These multicentre, double-blind, placebo-controlled studies recruited over 2000 patients with stable COPD, randomized to receive sibenadet (500 microg) or placebo, pressurized metered-dose inhaler (pMDI) (three times daily) for a period of 12 or 26 weeks. Diary cards were completed daily by patients throughout the study to record BCSS scores, peak expiratory flow (PEF), study drug and rescue bronchodilator usage, changes in concomitant medication and adverse events. The primary endpoints were defined as change from baseline to the final 4 weeks of the treatment period in mean BCSS total score, and forced expiratory volume in one second (FEV1) measured 1 hour after administration of the final dose of study drug and expressed as a percentage of the predicted FEV1. In addition, clinic assessments were made to determine changes in pulmonary function, health-related quality of life, perception of treatment efficacy and adverse events. Despite initial improvements in mean daily BCSS total scores in patients receiving sibenadet, the difference in the change from baseline to the final 4 weeks of the treatment period between the two treatment groups was neither statistically significant, nor considered to be of clinical importance. Although marked bronchodilator activity was seen early on with sibenadet treatment, the duration of effect diminished as the studies progressed. Sibenadet use was not associated with any safety concerns. These studies, utilizing the novel BCSS, have clearly illustrated that, despite initial symptomatic improvement with sibenadet therapy, this clinical benefit was not sustained over the course of the study.

Treatment of acute severe asthma and chronic obstructive pulmonary disease in Danish hospitals. Do national recommendations improve on the quality of the treatment?

Studies have demonstrated suboptimal treatment of acute severe asthma and chronic obstructive pulmonary disease (COPD). We examined the quality of treatment in Denmark and the effect of intervention, by publication of recommendations for standardised treatment. All 70 hospitals in Denmark with emergency facilities participated in a telephone questionnaire, examining treatment behaviours among house officers. The survey was repeated 3 years later, after publication of national recommendations for treatment of acute exacerbations of asthma and COPD. The response rate in both surveys was 100%. An insufficient handling of nebulisers, a huge variation in the delivered dose of bronchodilators and a suboptimal use of corticosteroids was found. A significant trend towards more liberate use of oxygen was seen in both asthma (3.2 l min(-1) versus 4.8 l min(-1), P<0.001) and COPD (1.5 l min(-1) versus 1.9 l min(-1), P = 0.047). Further, a huge difference in treatment behaviours was revealed from this survey The knowledge among house officers of basic principles of treatment was insufficient. Treatment behaviour was only moderately affected by national publication of detailed recommendations for treatment. This study indicates a need for implementing tools for quality control.

A proposal for a practical treatment guideline designed for the initial two-hours of the management of patients with acute severe asthma and COPD using the principles of evidence-based medicine.

We have proposed a clinical treatment guideline for the management of acute, severe asthma and chronic obstructive pulmonarydisease (COPD) using the principles of evidence-based medicine. The content is based upon practical clinical issues in need of consensus. A previous study has shown that this particular area is in serious need of quality control. Based on a strict 2 h time schedule with a unified treatment plan for both asthma and COPD, it is possible to secure for the patients a well-documented medical therapy promoting decision-making and clarification of the patient within this time limit. A summary of the statements is presented in a one-page, user-friendly format in order to cope with the clinician's need of having access to published evidence quickly and easily. A website (www.phanareth.dk or a website provided by Respiratory Medicine) has been established providing regular updates. A strategy for the implementation and the evaluation process has been planned after the publication of this paper. We believe this approach to be an important step towards an increase in the quality of guidelines and also a tool to make "guideline writers" aware of the responsibility of making their recommendations work.

A homologue of the Rad18 postreplication repair gene is required for DNA damage responses throughout the fission yeast cell cycle.

Cells activate DNA repair pathways and cell cycle checkpoints when they suffer damage to their genome. They also activate tolerance pathways that facilitate survival. In Escherichia coli, a mechanism known as postreplication repair (PRR) is used to bypass lesions that would otherwise present a physical block to DNA polymerase. PRR has also been proposed to occur in eukaryotic cells, although the partitioning of DNA synthesis to a discrete S-phase would suggest that it is only operative within a defined period of the cell cycle. Eukaryotic PRR has been most extensively studied in the budding yeast Saccharomyces cerevisiae. Two important genes for components of this repair pathway are RAD6, which encodes an ubiquitin-conjugating enzyme, and RAD18, which encodes a RING-finger protein and forms a heterodimer with Rad6p. Rad18p can also bind to DNA. We report here the identification of the Schizosaccharomyces pombe homologue of RAD18, which we have denoted rhp18. rhp18 mutants are hypersensitive to DNA-damaging agents, but show this hypersensitivity throughout the cell cycle. rhp18 mutants are characterised by a longer than usual DNA damage checkpoint arrest that is required for their residual viability following irradiation. Genetic analyses show that rhp18 controls a unique DNA damage repair/tolerance pathway that extends beyond the requirement to tolerate damage during S-phase, suggesting a broader definition of the function of this eukaryotic PRR protein.

Mutational analysis of the proteolytic domain of pregnancy-associated plasma protein-A (PAPP-A): classification as a metzincin.

The bioavailability of insulin-like growth factor (IGF)-I and -II is controlled by six IGF-binding proteins (IGFBPs 1-6). Bound IGF is not active, but proteolytic cleavage of the binding protein causes release of IGF. Pregnancy-associated plasma protein-A (PAPP-A) has recently been found to cleave IGFBP-4 in an IGF-dependent manner. To experimentally support the hypothesis that PAPP-A belongs to the metzincin superfamily of metalloproteinases, all containing the elongated zinc-binding motif HEXXHXXGXXH (His-482-His-492 in PAPP-A), we expressed mutants of PAPP-A in mammalian cells. Substitution of Glu-483 with Ala causes a complete loss of activity, defining this motif as part of the active site of PAPP-A. Interestingly, a mutant with Glu-483 replaced by Gln shows residual activity. Known metzincin structures contain a so-called Met-turn, whose strictly conserved Met residue is thought to interact directly with residues of the active site. By further mutagenesis we provide experimental evidence that Met-556 of PAPP-A, 63 residues from the zinc-binding motif, is located in a Met-turn of PAPP-A. Our hypothesis is also supported by secondary-structure prediction, and the ability of a 55-residue deletion mutant (d[S498-Y552]) to express and retain antigenecity. However, because PAPP-A differs in the features defining the individual established metzincin families, we suggest that PAPP-A belongs to a separate family. We also found that PAPP-A can undergo autocleavage, and that autocleaved PAPP-A is inactive. A lack of unifying elements in the sequences around the found cleavage sites of PAPP-A and a variant suggests steric regulation of substrate specificity.

Pregnancy-associated plasma protein-A (PAPP-A) cleaves insulin-like growth factor binding protein (IGFBP)-5 independent of IGF: implications for the mechanism of IGFBP-4 proteolysis by PAPP-A.

Pregnancy-associated plasma protein-A (PAPP-A) has recently been identified as the proteinase responsible for cleavage of insulin-like growth factor binding protein (IGFBP)-4, an inhibitor of IGF action, in several biological fluids. Cleavage of IGFBP-4 by PAPP-A is believed to occur only in the presence of IGF. We here report that in addition to IGFBP-4, PAPP-A also cleaves IGFBP-5. Cleavage occurs at one site, between Ser-143 and Lys-144 of IGFBP-5. In the presence of IGF, IGFBP-4 and -5 are cleaved with similar rates by PAPP-A. Interestingly, cleavage of IGFBP-5 by PAPP-A does not require the presence of IGF, but is slightly inhibited by IGF. These findings have implications for the mechanism of proteolysis of IGFBP-4 by PAPP-A, suggesting that IGFBP-4 binds IGF, which then becomes a PAPP-A substrate. Using highly purified, recombinant proteins, we establish that (1) PAPP-A cleavage of IGFBP-4 can occur in the absence of IGF, although the rate of hydrolysis is very slow, and (2) IGF is unable to bind to PAPP-A. We thus conclude that IGF enhances proteolysis by binding to IGFBP-4, not by interaction with PAPP-A, which could not previously be ruled out.

Pregnancy-associated plasma protein-A2 (PAPP-A2), a novel insulin-like growth factor-binding protein-5 proteinase.

A novel metalloproteinase with similarity to pregnancy-associated plasma protein-A (PAPP-A), which we denoted PAPP-A2, has been identified. Through expression in mammalian cells we showed that recombinant PAPP-A2 polypeptide of 1558 residues resulted from processing of a 1791-residue prepro-protein. Unlike PAPP-A, PAPP-A2 migrated as a monomer (of 220 kDa) in non-reducing SDS-polyacrylamide gel electrophoresis. The prepro-parts of PAPP-A2 and PAPP-A are not homologous, but mature PAPP-A2 shares 45% of its residues with PAPP-A. Because PAPP-A specifically cleaves insulin-like growth factor-binding protein (IGFBP)-4, one of six known modulators of IGF-I and -II, we looked for a possible PAPP-A2 substrate among the members of this family. We showed that PAPP-A2 specifically cleaved IGFBP-5 at one site, between Ser-143 and Lys-144. In contrast to the cleavage of IGFBP-4 by PAPP-A that strictly requires the presence of IGF, the cleavage of IGFBP-5 by PAPP-A2 was IGF-independent. Recent data firmly establish PAPP-A and IGFBP-4 as an important functional pair in several systems. Because of its close relationship with PAPP-A, both structurally and functionally, PAPP-A2 is a likely candidate IGFBP-5 proteinase in many tissues and conditioned media where IGFBP-5 proteolysis has been reported.

[Utilization of anti-asthmatic drugs among Danish children in 1998]. / Danske børns brug af asthmamedicin i 1998.

INTRODUCTION: The aim of the study was to evaluate the use of anti-asthmatics among Danish children in 1998. METHODS: Patient specific data were collected on anti-asthmatics (ATC-group R03) prescribed for children aged 0-15 years in 1998. Data included a total of 381,557 prescriptions for 139,727 individuals. RESULTS: Anti-asthmatics were prescribed for 13.9% of all Danish children on one or several occasions in 1998. The highest one-year prevalence and incidence rate of drug use was found for children aged 0-2 years. Most children were exclusively treated with either a short acting beta 2-agonist (66.7%) or an inhaled steroid (6.5%). Only 26.2% received both types of anti-asthmatics. CONCLUSION: In conclusion, anti-asthmatics were predominantly prescribed for the youngest children. Most children were exclusively treated with a short acting beta 2-agonist in 1998, which is only recommended in the case of mild intermittent asthma.

Expression of recombinant human pregnancy-associated plasma protein-A and identification of the proform of eosinophil major basic protein as its physiological inhibitor.

Pregnancy-associated plasma protein-A (PAPP-A), originally known from human pregnancy serum, has recently been demonstrated to be a metzincin superfamily metalloproteinase involved in normal and pathological insulin-like growth factor (IGF) physiology. PAPP-A specifically cleaves IGF-binding protein (IGFBP)-4, one of six antagonists of IGF action, which results in release of IGF bound to IGFBP-4. IGFBP-4 is the only known PAPP-A substrate. Its cleavage by PAPP-A uniquely depends on the presence of IGF. We here report mammalian expression and purification of recombinant 1547-residue PAPP-A (rPAPP-A). The recombinant protein is secreted as a homodimer of about 400 kDa composed of two 200-kDa disulfide-bound subunits. Antigenically and functionally, rPAPP-A behaves like the native protein. In human pregnancy, PAPP-A is known to circulate as a 500-kDa disulfide-bound 2:2 complex with the proform of eosinophil major basic protein (proMBP), PAPP-A/proMBP. A comparison between rPAPP-A and pregnancy serum PAPP-A/proMBP complex surprisingly reveals a difference greater than 100-fold in proteolytic activity, showing that proMBP functions as a proteinase inhibitor in vivo. We find that polyclonal antibodies against PAPP-A abrogate all detectable IGFBP-4 proteolytic activity in pregnancy serum, pointing at PAPP-A as the dominating, if not the only, IGFBP-4 proteinase present in the circulation. We further show that pregnancy serum and plasma contain traces (<1%) of uncomplexed PAPP-A with a much higher specific activity than the PAPP-A/proMBP complex. The measurable activity of the PAPP-A/proMBP complex probably results from the presence of a minor subpopulation of partly inhibited PAPP-A that exists in a 2:1 complex with proMBP. Inhibition of PAPP-A by proMBP represents a novel inhibitory mechanism with the enzyme irreversibly bound to its inhibitor by disulfide bonds.