PubMed Health⌕ Search

Biomedical subjects

E M Salonen

Publications and source records attributed to E M Salonen.

At least 19 recordsLinked to original sources
PubMed1998

Human recombinant Puumala virus antibodies: cross-reaction with other hantaviruses and use in diagnostics.

A panel of seven human monoclonal Fabs against Puumala virus (PUU) nucleocapsid protein (N) was obtained by panning an antibody phage-display library prepared from the spleen of a PUU-immune individual. Three antibodies reacted in immunoblotting and cross-reacted strongly with Tula and Sin Nombre virus recombinant N proteins. These antibodies mapped to the amino terminus of the N protein. One PUU glycoprotein 2 (G2)-specific Fab obtained against a novel epitope (G2c) cross-reacted with Khabarovsk virus but not with the other hantavirus serotypes. An N protein-specific Fab was successfully used as capture antibody to detect PUU-specific serum IgG and IgM antibodies in an enzyme immunoassay. The result demonstrates the usefulness of recombinant human Fabs as potential diagnostic tools.

Antibodies, Monoclonal↗
PubMed1996

Human glioma U-251 cells contain type 1 plasminogen activator inhibitor in a rapidly releasable form.

Because recent information suggests that the localized deposition of protease inhibitors is one mechanism by which cells regulate pericellular proteolysis during tissue invasion, the distribution of type 1 plasminogen activator inhibitor (PA1-1) associated with the invasive human glioma cell line U-251 was investigated. Direct and reverse fibrin zymography indicated the presence of urokinase-like plasminogen activator (u-PA) and PAI-1 in U-251 conditioned media and cell lysates. PA1-1 antigen was detected immunologically in cytoplasmic granules present within cellular processes of U-251 cells and these organelles could be isolated on Percoll density gradients in a high density band. In contrast, u-PA activity and another secreted protein, amyloid beta-protein precursor, were only present in the low density region of the gradients. Functional analysis of PAI-1 in the granules contained within the high density fractions revealed the presence of active PAI-1. Incubation of U-251 cells with the secretagogue, 8-bromoadenosine 3':5'-cyclic monophosphate, resulted in a 3-fold increase in the release of PAI-1 in the media conditioned by these cells. These data suggest that the human glioma cell line U-251 contains PAI-1 in a rapidly releasable form, which may provide another mechanism by which these tumors could regulate proteolytic activity in a localized manner.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Human autoantibody recognition of DNA.

Combinatorial IgG Fab phage display libraries prepared from a systemic lupus erythematosus (SLE) donor and a healthy donor were affinity selected against human placental DNA. Human monoclonal antibody Fab fragments specific for DNA were isolated from both libraries, although Fabs of the highest affinity were isolated only from the lupus library. Generally, apparent affinities of the Fabs for human placental DNA, purified double-stranded DNA, and denatured DNA were approximately equivalent. Surface plasmon resonance indicated Fab binding constants for a double-stranded oligodeoxynucleotide of 0.2-1.3 x 10(8) M-1. The higher-affinity Fabs, as ranked by binding to human placental DNA or to the oligonucleotide probe, tested positive in the Crithidia luciliae assay commonly used in the diagnosis of SLE, and interestingly the genes encoding the heavy-chain variable regions of these antibodies displayed evidence of only minimal somatic hypermutation. The heavy chains of the SLE Fabs were characterized by a predominance of basic residues toward the N terminus of complementarity-determining region 3 (CDR3). The crucial role of heavy-chain CDR3 (HCDR3) in high-affinity DNA recognition was suggested by the creation of DNA binding in an unrelated antibody by HCDR3 transplantation from SLE antibodies. We propose that high-affinity DNA-binding antibodies can arise in SLE without extensive somatic hypermutation in the variable-region genes because of the expression of inappropriate HCDR3s.

Amino Acid Sequence↗
PubMed1992

Cloning and sequencing of Puumala virus Sotkamo strain S and M RNA segments: evidence for strain variation in hantaviruses and expression of the nucleocapsid protein.

The prototype Puumala virus (PV) Sotkamo strain small (S) and medium (M) RNA genome segments were amplified by the polymerase chain reaction (PCR), cloned and sequenced. The S segment is 1830 nucleotides long with an open reading frame coding for 433 amino acids. The identity to the PV Hällnäs strain was 83% at the nucleotide and 96% at the amino acid level. The M segment in the Sotkamo strain is 3616 nucleotides long and contains one open reading frame of 1148 amino acids with 83% nucleotide and 94% amino acid identity to the Hällnäs strain. Most amino acid changes were conservative and the five predicted glycosylation sites are identical. The amino acid identity to the prototype hantavirus, Hantaan virus, was 62 and 54% for S and M segments, respectively. The coding region of the S segment was further amplified by PCR, ligated to pEX vectors and expressed in Escherichia coli as a beta-galactosidase fusion protein and was seen to be specifically detected by nephropathia epidemica sera in immunoblotting.

Amino Acid Sequence↗
PubMed1992

Retinal pigment epithelial cells secrete urokinase-type plasminogen activator and its inhibitor PAI-1.

Secretion of plasminogen activators and their inhibitors was examined in cultures of human retinal pigment epithelial (RPE) cells. The methods employed were zymography and reverse zymography, solid-phase immunocapture assay, metabolic labeling followed by immunoprecipitation, and immunofluorescence. The results showed that these cells produce urokinase-type plasminogen activator (u-PA) and a plasminogen activator inhibitor (PAI) which is immunologically and biochemically similar to PAI-1. Tissue-type plasminogen activator activity (t-PA) was not detected, but we detected small amounts of t-PA in an inactive complex with inhibitor in RPE cell-conditioned media. We conclude that RPE cells have the potential to utilize u-PA-catalyzed plasminogen activation which is subject to regulation by PAI-1. These results may have a bearing on the pathogenesis of proliferative retinal diseases.

Antibodies, Monoclonal↗
PubMed1992

Tear plasmin activity with contact lens wear.

Plasmin, a proteolytic enzyme, has been detected in the tears of patients experiencing anterior ocular disease, and during contact lens wear. Using a radial caseinolysis procedure, we examined tear plasmin levels in 66 patients who were wearing soft and rigid lenses for daily and extended wear. Compared to non-contact lens wearers, patients wearing soft and rigid lenses for extended wear were significantly more likely to exhibit tear plasmin activity. Eight hours of open-eye thick HEMA lens wear did not induce tear plasmin activity in a group of 10 subjects. However, significant increases in tear plasmin activity were recorded after short-term (1 hour) eye closure with and without lens wear, and following overnight (8 hours) eye closure without lens wear. Overnight eye closure also resulted in significantly increased numbers of epithelial cells and leucocytes in the tear fluid. Our results suggest that increased tear plasmin activity during extended contact lens wear may be attributable to the effects of eye closure rather than hypoxia or the presence of the contact lens per se.

Adult↗
PubMed1991

Procollagen-III in serum, plasminogen activation and fibronectin in bronchoalveolar lavage fluid during and following irradiation of human lung.

In the search for predictors of late radiation-induced lung injury we studied procollagen type III peptide concentration (P-III-P) in serum as well as fibronectin and plasminogen activation in bronchoalveolar lavage (BAL) fluid during and following irradiation of human lung. The patients received either high-dose hemithorax irradiation for pleural mesothelioma (11 patients) or high-dose irradiation with individually shaped fields for non-small cell lung cancer (12 patients). The severity of radiation fibrosis was assessed clinically from CT scans 6 months and 12 months after treatment. Four scores were used: severe, moderate, mild, or normal. Radiological lung injury varied from "severe" (9 patients) to near absence of injury-"normal" (6 patients). Serum levels of P-III-P, when measured weekly during the 5-week period of radiotherapy or at several time-points after treatment, did not show consistent changes, nor did the levels correlate with the score for radiation fibrosis as assessed by CT scanning. Changes in fibronectin levels or in markers of plasminogen activation in BAL fluid did not correlate with the development of late lung injury. The levels of BAL fluid plasmin and plasminogen activator as assessed zymographically, but not the free net enzyme values, showed a tendency to be elevated in patients with severe radiation-induced lung injury, suggesting a possible role for inhibitors of the plasminogen activation cascade in the process of radiation-induced lung injury.

Adult↗
PubMed1990

Thy-1 is a neuronal and glial surface antigen which interacts with matrix proteins and plasminogen activator.

Thy-1 antigen is expressed at high levels in the thymus and in adult brain of rodents however its function remains undetermined. We report that immobilised Thy-1 binds laminin, fibronectin and the less active precursor form of the tissue type plasminogen activator (t-PA) yet it does not bind urokinase. The incorporation of serine protease inhibitors within the experimental procedures suggested that Thy-1 bound to the lysine-containing, protein-binding domain of t-PA thus leaving the active site available to interact with other proteins. By using an immunocytochemical approach designed to maximally preserve Thy-1 antigenicity, we were able to demonstrate that in the adult rat peripheral nervous system (PNS) Thy-1 was seen to co-localise with laminin on the Schwann cell membranes and accumulated at the nodes of Ranvier within sciatic nerve. The only neuronal structures to express Thy-1 within the PNS were the unmyelinated nerve fibres. In the adult rat central nervous system (CNS), the most distinct and novel association of Thy-1 was its presence along the myelin forming glial cells and their fibres.

Animals↗
PubMed1990

Culture of retinal pigment epithelial cells from subretinal fluid.

Culture of cells from subretinal fluid (SRF) was performed using 29 SRF samples obtained at retinal reattachment surgery. Proliferating cells were found in 58.6% of the samples studied. The cells were of retinal pigment epithelial (RPE) origin, as evidenced by their brown pigmentation in primary culture and their positive immunostaining for cytokeratins 8/18. The age of the patients did not affect the proliferative capacity of the cells. Proliferating cells were present in all samples from eyes with proliferative vitreoretinopathy (PVR) of grade C1 or more. In primary culture the cells had a fibroblast-like morphology, resembling that of ordinary RPE cells exposed to the vitreous. We conclude that the SRF of many patients with PVR contains viable proliferating RPE cells and that SRF offers a new source of RPE cells for studies on the pathogenesis of PVR.

Adolescent↗
PubMed1990

Effects of the Schirmer test on the fibrinolytic system in the tear fluid.

Human tear fluid was collected with blunted glass capillaries before and after performing the Schirmer test (ST). The test caused an increase in the tear fluid (TF) plasmin concentration (from 0.40 +/- 0.29 microgram ml-1 (mean +/- S.E.M.) to 1.14 +/- 0.26 microgram ml-1; Mann-Whitney test P less than 0.001) and a decrease in plasminogen activator activity (from 2.04 +/- 0.24 IU ml-1 to 1.04 +/- 0.17 IU ml-1; Mann-Whitney test P less than 0.002). In the filter paper used for ST, that segment that had been in contact with the conjunctiva (5 mm) usually contained higher amounts of plasmin than the following 5 mm of the paper overhanging the lidmargin. The present results indicate that the TF collection may affect the plasminogen activator-plasmin system in TF, depending on the collection method used.

Fibrinolysin↗
PubMed1990

Fibronectin concentration in cerebrospinal fluid reflects early central nervous system involvement in children with acute lymphoblastic leukemia.

We measured concentrations of fibronectin (FN) in the cerebrospinal fluid (CSF) in long-term follow-up patients with acute lymphoblastic leukemia (ALL). In 11 patients with neuroleukemia the CSF-FN level was elevated already at the time of diagnosis of ALL, 3.8 +/- 0.6 mg/l, increased during therapy to 4.7 +/- 0.5 mg/l, and at the time of concurrent blast cell finding it was 5.5 +/- 1.0 mg/l. In 11 patients with no subsequent CNS leukemia, the mean CSF-FN level was 2.4 +/- 0.6 mg/l at the time of diagnosis of ALL and 2.8 +/- 0.6 mg/l during therapy, and increased to 3.2 +/- 0.8 mg/l. The neuroleukemia rate was 43% in patients with initial CSF-FN levels greater than 2 mg/l, compared with 5% in patients with CSF-FN levels less than or equal to 2 mg/l (p less than 0.005) in a group of 45 long-term follow-up patients with ALL. Regression analysis on the 21 clinical or laboratory parameters studied showed that the only variable independently associated with CSF-FN was the total protein concentration in the CSF; this, however, explained only 14% of the observed variation in the CSF-FN concentration and did not show any correlation with CNS involvement. We conclude that the CSF-FN test at diagnosis of ALL showed significant differences between groups of patients with and without CNS leukemia, and may prove to be a new early marker for neuroleukemia.

Analysis of Variance↗
PubMed1989

Lipoprotein(a) binds to fibronectin and has serine proteinase activity capable of cleaving it.

The plasma concentration of human lipoprotein(a) [Lp(a)] is correlated with the risk of heart disease. A distinct feature of the Lp(a) particle is the apolipoprotein (a) [apo(a)], which is associated with apoB-100, the main protein component of low-density lipoprotein. We now report that apo(a), which has extensive homology to plasminogen, binds to immobilized fibronectin. The binding of Lp(a) was localized to the C-terminal heparin-binding domain of fibronectin. Incubation of Lp(a) with fibronectin resulted in fragmentation of fibronectin. The cleavage pattern, as visualized by gel electrophoresis and immunoblotting, was reproducibly obtained with Lp(a) purified from five different individuals and was distinct from that obtained upon proteolysis of fibronectin by plasmin or kallikrein. The use of synthetic peptide substrates demonstrated that the amino acid specificity for Lp(a) was arginine rather than lysine. The proteolytic activity of Lp(a) was localized to apo(a) and experiments with inhibitors indicated that the proteolytic activity was of serine proteinase-type.

Fibronectins↗
PubMed1989

Interaction of plasminogen activator inhibitor (PAI-1) with vitronectin.

Immobilized vitronectin was found to bind both purified plasminogen activator inhibitor type 1 (PAI-1) and the PAI-1 in conditioned culture medium of human sarcoma cells. Similarly, immobilized PAI-1 bound both purified vitronectin and vitronectin from normal human serum. These interactions were demonstrated using both enzyme immunoassay and radioiodinated proteins. Solid-phase vitronectin bound PAI-1 with Kd 1.9 x 10(-7) M, and the reverse interaction gave a Kd 5.5 x 10(-8) M. Evidence was also found for a second type of binding with a Kd below 10(-10) M. The molar ratios of the two proteins in the complex at the saturation levels were approximately one molecule of soluble PAI-1 bound per three molecules of immobilized vitronectin and approximately one molecule of soluble vitronectin being bound per one molecule of immobilized PAI-1. Binding of PAI-1 to vitronectin did not lead to an irreversible loss of the ability of PAI-1 to inhibit urokinase (u-PA) and tissue-type plasminogen activator (t-PA). Active u-PA released vitronectin-bound 125I-labeled PAI-1 radioactivity, suggesting that u-PA interacts with the complex. The Mr 50,000 urokinase cleavage product of PAI-1 also bound to vitronectin, but this bound fragment did not inhibit u-PA. Binding of PAI-1 to vitronectin did not interfere with the ability of vitronectin to promote the adhesion and spreading of cells. These results suggest that the interaction between vitronectin and PAI-1 may serve to confine pericellular u-PA activity to focal contact sites where cells use proteolysis in regional detachment.

Glycoproteins↗
PubMed1989

Elevated cerebrospinal fluid fibronectin concentration at diagnosis indicates poor prognosis in children with acute lymphoblastic leukemia.

We investigated whether the concentration of fibronectin (FN) in the cerebrospinal fluid (CSF) could be used for identifying patients with subclinical blast-cell infiltration in the central nervous system (CNS) and an increased risk of CNS relapse later in the course of their leukemia. Our series comprised 36 children with newly diagnosed acute lymphoblastic leukemia (ALL). The mean follow-up time was 54 months (range 5 to 96 months). The median concentration of CSF-FN at diagnosis was 2.24 mg/l (range 0.78 to 7.04 mg/l). The 3-year continuous complete remission rate for the 16 patients with CSF-FN concentrations less than or equal to 2 mg/l was 93% as compared with 37% for the 19 patients with CSF-FN greater than 2 mg/l (p = 0.001). When multivariate analysis was performed, the CSF-FN concentration retained its prognostic significance. When all relapses were considered as failures, the relative risks of relapse for patients with CSF-FN less than or equal to 2 mg/l and greater than 2 mg/l were I and 15.8 (95% confidence limits 1.8-135.6, p less than 0.02), respectively. If only CNS relapses (isolated and combined) were considered as failures, relative risks for the above-mentioned groups were I and 11.6 (1.4-99.5, p less than 0.05), respectively. We conclude that determination of the CSF-FN concentration may provide a new means of evaluating the CSF in children with ALL and may prove to be a sensitive indicator of leukemic CNS infiltration.

Adolescent↗
PubMed1989

Plasminogen activator and its enhancement in differentiating mouse Friend erythroleukemia cells.

Urokinase-type plasminogen activator (u-PA) activity was found in the medium as well as in the lysates of cultured uninduced Friend leukemia (FL) cells. PA activity progressively increased during the cell differentiation induced by dimethyl sulphoxide (DMSO), 4-hydroxy-3-methoxybenzaldehyde or hypoxanthine. Both the differentiation and the enhancement of PA activity in cultures of DMSO-induced cells were blocked by treating the cells with 1 microM dexamethasone. A highly significant correlation (rs = 0.93) was found between the number of hemoglobinized cells and the rate of PA secretion, indicating that the increase in PA activity coincides with late events of the differentiation process. FL cells specifically adhere to fibronectin-coated surfaces but tend to lose this property during the differentiation process. Anti-u-PA IgG antibodies promoted the attachment of differentiating cells to fibronectin-coated surfaces, suggesting that u-PA plays a role in the detachment of FL cells from fibronectin immobilized on the growth substratum.

Animals↗