Classification of CSF samples from normal and post-partum psychotic women using chromatographic profiles with bilinear projections: a multivariate approach.

This paper demonstrates how chromatographic profiles of cerebrospinal fluid (CSF) have been subjected to multivariate data analysis to discriminate between CSF samples from women with post-partum psychosis and those from healthy women. Instead of peak-heights or areas, digitally defined chromatographic profiles were examined using principal component analysis (PCA). In accordance with the diagnosis, we have found a complex profile pattern of at least ten composite peaks that discriminates between these groups. Two of these peaks were for the discrimination particularly clearly between the two groups. We speculate that these findings can be useful in the diagnosis of post-partum psychosis, increasing diagnostic precision and having both clinical and prognostic implications.

Comparison of plasminogen activator inhibitor activity and antigen in plasma samples.

A double antibody radioimmunoassay for determination of plasminogen activator inhibitor (PA-inhibitor) in plasma samples has been developed. The reliability of the method as assessed by determining the specificity, the accuracy, the detectability and the variability seems sufficient for use in clinical practice. The correlation between PA-inhibitor antigen as measured with this method and PA-inhibitor activity as measured with a spectrophotometric assay in 111 patients with thrombotic diseases was very good (r = 0.89). As calculated from the regression line or from the mean activity and mean antigen values a specific activity of about 800,000-900,000 arb U/mg was obtained for PA-inhibitor in these samples. In 15 healthy individuals a similar figure was obtained. The results suggest that PA-inhibitor in most plasma samples is fully active or close to fully active. PA-inhibitor activity and PA-inhibitor antigen have also been measured after venous occlusion. The data suggest that small amounts of PA-inhibitor is released on venous occlusion, but at the same time an inactivation takes place, most likely due to the formation of enzymatically inactive complex with simultaneously released t-PA.

Immunological relationship between plasminogen activator inhibitors from different sources.

Polyclonal antibodies have been raised against the inhibitor moiety in the purified complex between tissue plasminogen activator and its fast inhibitor (PA-inhibitor) in human plasma/serum. A radioimmunoassay for quantitation of PA-inhibitor antigen was developed. The polyclonal antiserum and a previously described monoclonal antibody against the PA-inhibitor (14) have been used to study the immunological relationship between PA-inhibitors from plasma, serum, platelets, placenta extract and conditioned media from Hep G2 and HT 1080 cells. It was demonstrated that the ratio between PA-inhibitor activity and antigen varied considerably between the different sources. In the plasma samples studied, similar activity and antigen concentrations were found, suggesting that the PA-inhibitor in these samples mainly was in an active form. On the other hand the other sources seemed to contain variable amounts of inactive PA-inhibitor forms. Immunoadsorption experiments revealed that the PA-inhibitor (activity and antigen) from all the sources were specifically bound to the insolubilized antibodies (polyclonal and monoclonal). In no case, however, could active PA-inhibitor be eluted from the immunoadsorption columns. Also the competitive radioimmunoassays suggested that the PA-inhibitors from the different sources studied, were closely immunologically related.

Monoclonal antibodies towards the fast inhibitor of tissue plasminogen activator from human plasma and serum.

Hybridoma cells were produced by fusing mouse myeloma cells (SP 2/0-Ag 14) with spleen cells from a Balb/c mouse, previously immunized with the partially purified complex between tissue plasminogen activator (t-PA) and its fast inhibitor from human plasma (serum). Screening with a radioimmunoassay revealed a number of hybridomas secreting antibodies directed towards the complex. Of these, about 1/3 reacted both with the complex and t-PA, whereas about 2/3 reacted only with the complex. Three of the latter hybridomas, producing antibodies directed towards the inhibitor-moiety in the complex have been cloned and the antibodies were studied in detail. PA-inhibitor activity in plasma or serum and t-PA/PA-inhibitor complex could be specifically adsorbed on all three insolubilized monoclonal antibodies (MC1, MC2 and MC3). None of the antibodies seems to be directed against structures of vital importance for the functional activity of the PA-inhibitor. In accordance with this finding the antibody with the highest avidity (MC1) reacts equally well with the PA-inhibitor alone or in complex with t-PA. A radioimmunoassay was developed with this antibody and significant displacement was obtained with samples with PA-inhibitor concentrations above 2 AU/mL. In 13 plasma samples with different levels of PA-inhibitory activity a significant correlation was obtained when comparing this activity with the PA-inhibitor antigen as measured with the radioimmunoassay (r = 0.88).

The role of the fibrinolytic system in deep vein thrombosis.

Some aspects of the function of the fibrinolytic system have been investigated in 37 patients with a recent incident of symptomatic and confirmed deep vein thrombosis and compared with findings in 20 healthy persons. New specific methods to measure tissue plasminogen activator (t-PA) activity and antigen before and after venous occlusion and the recently discovered fast inhibitor to t-PA were employed. Thirteen of the patients with deep vein thrombosis (35%) had t-PA activity less than 0.5 IU/ml after venous occlusion, whereas the lowest activity found among the healthy individuals was 0.56 IU/ml. The t-PA inhibitor level in the total patient group was 3.8 +/- 3.7 U/ml (range 0 to 15.0 U/ml; median 2.9 U/ml) as compared with 0.7 +/- 0.7 U/ml in the healthy (median 0.5, range 0 to 2.4 U/ml). In the 13 patients with low t-PA activity in postocclusion plasma samples the inhibitor level was 6.0 +/- 4.4 U/ml. Furthermore, in this group of patients a significantly lesser release of t-PA antigen (3.7 +/- 2.8 micrograms/L) was found as compared with that in the healthy individuals (9.5 +/- 6.0 micrograms/L). Thus, two months after their first incident of symptomatic deep vein thrombosis many of the patients (35%) were found to have decreased fibrinolytic activity. This is the result of highly increased plasma levels of a novel fast inhibitor toward t-PA in combination with a poor ability to release t-PA. Possibly the decreased fibrinolytic activity did play a role in the pathogenesis of deep vein thrombosis in these patients.

Determination of tissue plasminogen activator in plasma samples by means of a radioimmunoassay.

A solid phase double antibody radioimmunoassay for measuring tissue plasminogen activator (t-PA) in human plasma is described using purified human melanoma cell t-PA and specific goat anti-t-PA IgG. The concentration of t-PA antigen in citrated human plasma sampled at rest was 4.4 +/- 1.3 micrograms/l (mean +/- SD) for healthy individuals (n = 20). After 10 min of venous occlusion the level of t-PA antigen was increased to 13.9 +/- 6.2 micrograms/l. The accuracy was monitored by recovery experiments using plasma from nine healthy individuals and nine patients to which was added low (5 micrograms/l) and high (25 micrograms/l) levels of purified t-PA. The detection limit of the method was estimated as 0.08 micrograms/l. An excellent correlation was found on comparing the t-PA antigen increase with the t-PA activity increase obtained during venous occlusion. In plasma collected prior to venous stasis, the total concentration of detectable t-PA antigen is found mainly in an inactive form. In contrast the t-PA antigen released upon venous occlusion seems to be largely in an active form.