Tytti Kärkkäinen

Evaluation of a rapid strip test for insulin-like growth factor binding protein-1 in the diagnosis of ruptured fetal membranes

We evaluated the clinical usefulness of a new bedside test (PROM TEST) for insulin-like growth factor binding protein-1 (IGFBP-1) in the detection of ruptured fetal membranes (ROM). Cervicovaginal secretion was sampled between 15 and 37 weeks of gestation from asymptomatic women with apparently intact membranes and from women with clinically confirmed ROM, as well as from symptomatic women with suspected ROM based on history. IGFBP-1 in samples was detected with a dipstick based on immunochromatography. The test result was positive in 100% of cases with unequivocal ROM and in 5.3% of cases with apparently intact membranes. Furthermore, the PROM TEST was positive in 64 of 181 patients evaluated for suspected ROM based on history, but in whom the diagnosis could not be clinically confirmed at the initial evaluation. Fifty of the 64 women (78.1%) were delivered prematurely (< 37 weeks). Five of the 117 PROM-negative patients had elective cesarean section for reasons unrelated to ROM before 37 weeks and 10 of the remaining 112 patients (8.9%) had preterm delivery. Women with equivocal ROM and a positive test result had a 6.9-fold increased relative risk (95% confidence interval 4.2-11.4) of preterm delivery compared with women who had a negative result at the time of evaluation. Multiple logistic regression including PROM TEST result, contractions, vaginal bleeding and cervical changes indicated that a positive PROM TEST result was an independent predictor of preterm delivery (P = 0.0001). In summary, a positive PROM TEST result identifies ROM with high sensitivity and a negative result effectively excludes those with intact membranes. In patients with suspected but clinically unconfirmed ROM, the positive test result is associated with increased risk of preterm delivery, suggesting that microruptures of fetal membranes can also be detected by the PROM TEST.

Measurement of insulin-like growth factor binding protein-1 in cervical/vaginal secretions: comparison with the ROM-check Membrane Immunoassay in the diagnosis of ruptured fetal membranes.

Insulin-like growth factor binding protein-1 (IGFBP-1) is a major protein in amniotic fluid. In this study, we evaluated the diagnostic potential of IGFBP-1 measurement in cervical/vaginal secretions as an indicator of ruptured fetal membranes. Data were also compared with those obtained by the ROM-check Membrane Immunoassay (Adeza Biochemical, Sunnyvale, California) that is based on the detection of fetal fibronectin in vaginal fluid. In women with intact membranes and not in labor, the concentration of IGFBP-1 in specimens obtained from the cervix and immersed in 0.5 ml of assay buffer ranged from < 0.5 to 90 micrograms/l, whereas in specimens obtained less than 8 h after spontaneous or artificial rupture of membranes it varied between 175 and 20,000 micrograms/l, the median being 1,900 micrograms/l. The values greater than 100 micrograms/l were interpreted as containing amniotic fluid. The IGFBP-1 measurement and the ROM-check Membrane Immunoassay were carried out parallel in the vaginal swab specimens obtained from 54 pregnant women from 1 h to 1 week after the rupture. Twenty-four women had ROM confirmed from 1 h to 1 week earlier. In this group of patients, IGFBP-1 concentration > 100 micrograms/l had a sensitivity of 75% and a specificity of 97% in diagnosis of ROM. The corresponding numbers for a positive ROM-check were 92% and 80%. The positive predictive value was 95% for the IGFBP-1 measurement compared to 79% for the ROM-check test.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factor-binding protein-1 in cervical secretion as a predictor of preterm delivery

Background. The aim of the study was to evaluate whether the phosphorylated isoforms of insulin‐like growth factor‐binding protein‐1 (IGFBP‐1), a protein produced by the decidua, can be detected in cervical secretions of pregnant women with preterm uterine contractions, and whether their presence predicts an increased risk of preterm delivery.

Combination of cervical interleukin‐6 and ‐8, phosphorylated insulin‐like growth factor‐binding protein‐1 and transvaginal cervical ultrasonography in assessment of the risk of preterm birth

Objective To determine the value of combinations of cervical interleukin‐6 (IL‐6), cervical interleukin‐8 (IL‐8), the phosphorylated isoform of insulin‐like growth‐factor binding protein‐1 (IGFBP‐1), and cervical ultrasonography in the prediction of preterm birth.

Phosphorylated isoforms of insulin-like growth factor binding protein-1 in the cervix as a predictor of cervical ripeness.

OBJECTIVE To study the isoforms of insulin-like growth factor binding protein-1 (IGFBP-1) in cervical secretion and to evaluate whether their assessment could serve in prediction of cervical ripeness at term. METHODS We measured the concentrations of IGFBP-1 in cervical swab samples of 64 women scheduled for labor induction by amniotomy or cervical ripening with prostaglandin E2 gel. Two immunoenzymometric assays were used: a previously described assay 1, which detects the nonphosphorylated and lesser phosphorylated isoforms, and a novel assay 2, which detects the lesser and highly phosphorylated isoforms of IGFBP-1. A set of 39 amniotic fluid (AF) samples also was analyzed to compare the phosphorylation status of IGFBP-1 in cervical secretion with that in AF. RESULTS In all cervical samples, IGFBP-1 concentration was higher by assay 2 than by assay 1, whereas in all AF samples, the results were the opposite. Initially, the median IGFBP-1 concentration in the ripe cervices (Bishop scores 6 or greater; n = 29) was approximately four times as high as that in the unripe cervices (Bishop scores 5 or less; n = 35). The cervical IGFBP-1 concentrations increased eight-fold in 6 hours after the first application of PGE2. CONCLUSION Phosphorylated isoforms of IGFBP-1, different from those in AF, are present in the cervical secretion of women with intact fetal membranes and reflect cervical ripeness. A bedside test for those IGFBP-1 isoforms might help in predicting amenability for labor induction.

Isolation and immunologic properties of a heterogenous antigen with the characteristics of the heavy chain of human plasma kininogen

Kininogen antigen was purified from human plasma fraction IV by ion exchange chromatography, gel filtration and affinity chromatography with antibody specific immunoadsorbents. The immunologically pure glycoprotein had a mol. wt of approximately 60,000 and only one polypeptide chain by SDS-PAGE. An extensive charge heterogeneity by isoelectric focusing and gel filtration on polyacrylamide agarose could only in part depend on a comparatively high sialic acid content, but may be caused by differences in the carbohydrate structures sustained by lectin-binding heterogeneity on Con A-Sepharose. This antigen shares a dominating determinant with native plasma kininogens shown by complete patterns of identity in immunochemical analyses and with the monospecific antisera developed in rabbits against the heterogeneous components. The similar size, amino acid composition, low histidine content, lack of N-terminal amino acid and antigenic homogeneity fit all the so far known characteristics of the human kininogen heavy chain. Notably the antigenic determinant is resistant to degradation by activated kallikrein. This antigen with unimpaired immunologic activity may be a useful tool for preparation of antiserum for immunochemical determination of human plasma kininogen.

Conformation and sequence dependent antigenic determinants in human low molecular weight kininogen

Conformation and sequence-dependent antigenic determinants were investigated using a kinin-free low molecular weight kininogen isolated from Cohns plasma fraction IV. This antigen contains the determinants of the apparently intact heavy chain common to the high molecular weight and low molecular weight kininogens. Straightforward reduction and carboxymethylation destroyed the immunoreactivity of this molecule. Antiserum prepared against the reduced protein recognized both reduced and unreduced antigen showing the presence of both types of antigenic determinant. The corresponding antibodies were separated using immunoadsorbent columns. As shown by the higher avidity of the antibodies, the conformation-dependent determinants dominate the antigenic structure.

Kininogen by the SRI Method in Human Serum During an Acute Phase Inflammatory Reaction

The concentration of several serum proteins changes during the acute phase in inflammatory states.1 Kininogen belongs to this group of acute phase reactants as shown in our earlier studies and also with plasma from patients with rheumatoid arthritis.2 In early studies plasma kininogen was measured exclusively by estimation of the bradykinin equivalent by bio- assay on the isolated rat uterus or guinea pig ileum. 3 More recently a bradykinin enzyme immunoassay4, radioimmunoassay5 and rocket Immunoelectrophoresis6 were reported for the determination of HMr kininogen in plasma. A method designated to determination of the total plasma and serum kininogen by single radial immunodiffusion (SRI) was recently presented by us in detail.7 The SRI method was compared with and correlated to kininogen determined by the bradykinin equivalent and gives the corresponding normal values in human plasma and serum. This presentation deals with its application in a study of kininogen investigated in a serum material collected from patients during periods of treatment with immunotherapy in renal cell carcinoma.8–12 An infiammatory reaction provoked during the treatment was shown by the increase of a1-acid glycoprotein and some other acute phase reactants.

Determination of human plasma kininogen by a single radial immunodiffusion method and the bradykinin equivalent.

An SRI method is presented for the quantitation of native human plasma kininogen using a monospecific high avidity antiserum prepared against the conformational determinants of kininogen heavy chain (HC antigen). The SRI value of total human plasma kininogen averaged 0.260 +/- 0.052 g/l (+/- 2 SD) using a standard curve of normal human plasma in each assay (measuring range 0.016-0.260 g/l). The SRI data, confirmed by RIA, were compared with determination of the bradykinin equivalent by bioassay 4.30 +/- 0.052 mg/l (+/- 2 SD), generally accepted as a measure of total plasma kininogen. The SRI method does not discriminate between LMr and HMr kininogen but detects an increase of total kininogen independently of bradykinin release as a consequence of activated proteolysis. It is suggested that the SRI method can be applied to study levels of kininogen in clinical research.

Immunopurification of human plasma kininogens

Human plasma kininogens were purified by immunoadsorption on Sepharose columns using two different approaches, either removing protein impurities with the respective immunospecific polymers or applying an anti-kininogen-specific immunoadsorbent column. An anti-kininogen serum developed and investigated in this laboratory in earlier studies was used. This antiserum recognizes the native conformational determinants in the kininogen heavy chain, the common denominator in plasma kininogens, and reacts with three heterogeneous molecular forms of high mol. wt kininogen (mol. wts 103,000, 92,000 and 90,000) as well as with low mol. wt kininogen. Heterogeneity of kininogens was shown by SDS gel electrophoresis and immunoelectrophoresis. With the antibody-specific polymers the yield was 80-100% compared to 75% or lower when several consecutive immunoadsorption steps were applied to remove impurities. Both methods serve the purpose of preparing immunologically pure kininogens suitable for immunization.