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Biomedical subjects

J Selmer

Publications and source records attributed to J Selmer.

At least 19 recordsLinked to original sources
PubMed2000

Modulation of metabolism through transcriptional control has created new treatment opportunities for type 2 diabetes.

The discovery of the important metabolic and physiological role played by a family of transcription factors, the peroxisome proliferator activated receptors (PPAR), has opened up for a new understanding of the mode of action for the lipid lowering drugs known as fibrates and for the new glucose lowering compounds described as insulin sensitizers. Both of these classes of compounds have demonstrated significant efficacy in both animal models of the metabolic derangements characteristic for type 2 diabetes and in human clinical studies. The recognition of the role of these drugs as ligands for PPAR transcription factors and the development of new molecular and cellular tools to select and characterise new PPAR selective compounds will open up for the development of even better new drug candidates for the treatment of metabolic disorders associated with type 2 diabetes. With the combined strength of new transcriptional mapping technologies developed in the field of molecular biology, such as differential mRNA display and DNA microarray hybridisations, it will be possible to perform a detailed molecular characterisation of the transcriptional events involved in drug actions in cellular and tissue systems, and information gathered from such types of analysis will lead to an enormous amount of data, from which detailed knowledge of drug actions at the gene regulatory level will emerge.

Animals↗
PubMed1994

Human ventricular myosin light chain isotype 1 as a marker of myocardial injury.

A monoclonal enzyme immunoassay for measuring human ventricular myosin light chain isotype 1 (HVMLC1) in serum has been developed. To evaluate the method in patients with suspected myocardial injury, we studied 51 patients (16 acute myocardial infarction (AMI), 19 unstable angina pectoris (UAP), 9 stable angina pectoris, 3 nonischemic heart disease, 4 hip surgery patients), and 190 controls (blood donors). Serial blood-samples were drawn from patients; a single blood-sample from controls. The diagnostic value of the HVMLC1 assay was compared with total creatine kinase (CK), CKMB activity, CKMB mass concentration, lactate dehydrogenase isoenzyme 1 (LD1), troponin T (TnT) and mitochondrial-aspartate aminotransferase (m-ASAT). The detection limit of HVMLC1 was 0.4 microgram/l (linear range 0-20 micrograms/l). Sera from 190 reference persons did not contain detectable levels of HVMLC1 (< 0.4 microgram/l; 99% percentile). The coefficients of variation were 13% (1.0 microgram/l) and 3.1% (17.7 micrograms/l). Cross-reactivity with myosin from skeletal muscle was seen. Times to peak value were: CK 19.3 +/- 2.0, LD1 43.4 +/- 3.2, HVMLC1 72.9 +/- 7.0, and m-ASAT 67.3 +/- 5.6 h. Time-curves of HVMLC1 and m-ASAT were similar, whereas time-curves for HVMLC1 and TnT were quite different in most cases. Peak value of HVMLC1 was five times higher than CK peak value and eight times that of LD1. HVMLC1 appeared in the blood within hours after the onset of chest pain and in the majority remained for more than a week after AMI. Among patients with UAP 16% (3/19) had elevated HVMLC1 in serum, whereas elevated TnT was seen in 26% (5/19) and elevated CKMB mass in 26% (5/19). We conclude that the new HVMLC1 assay offers a sensitive diagnosis of myocardial injury. It is characterized by a wide diagnostic time window. The similarity of the HVMLC1 and m-ASAT curves indicates that it may be used to estimate the extent of myocardial necrosis.

Adult↗
PubMed1992

A specific immunologic assay for functional plasminogen activator inhibitor 1 in plasma--standardized measurements of the inhibitor and related parameters in patients with venous thromboembolic disease.

A new assay for functional plasminogen activator inhibitor 1 (PAI-1) in plasma was developed. The assay is based on the quantitative conversion of PAI-1 to urokinase-type plasminogen activator (u-PA)-PAI-1 complex the concentration of which is then determined by an ELISA employing monoclonal anti-PAI-1 as catching antibody and monoclonal anti-u-PA as detecting antibody. The assay exhibits high sensitivity, specificity, accuracy, and precision. The level of functional PAI-1, tissue-type plasminogen activator (t-PA) activity and t-PA-PAI-1 complex was measured in normal subjects and in patients with venous thromboembolism in a silent phase. Blood collection procedures and calibration of the respective assays were rigorously standardized. It was found that the patients had a decreased fibrinolytic capacity. This could be ascribed to high plasma levels of PAI-1. The release of t-PA during venous occlusion of an arm for 10 min expressed as the increase in t-PA + t-PA-PAI-1 complex exhibited great variation and no significant difference could be demonstrated between the patients with a thrombotic tendency and the normal subjects.

Blood Specimen Collection↗
PubMed1991

Detection of deep venous thrombosis with indium 111-labelled monoclonal antibody against tissue plasminogen activator.

The administration of a radiolabelled monoclonal antibody against tissue plasminogen activator allows detection of areas with increased fibrinolytic activity, i.e. those with an active thrombotic lesion. Eight patients with phlebographically verified deep venous thrombosis were examined. At the time of immunoscintigraphy study they were examined receiving anticoagulant therapy. Some 75-85 MBq indium 111-labelled antibody were injected, and scintigrams were obtained after 30 min and after 24 h. The precise site of the thrombus could not be visualized after 30 min due to high background activity, whereas after 24 h it was detectable in all patients. The thrombus/background ratios achieved are twice as high as those observed in a human antifibrin antibody study. These preliminary data suggest a high sensitivity of our t-PA-specific antibody for the detection of active deep venous thrombosis in man, and our antibody seems to offer theoretical advantages over both platelet and fibrin-specific antibodies.

Antibodies, Monoclonal↗
PubMed1991

Biological background subtraction improves immunoscintigraphy by subsequent injection of antigen.

We have developed an 111In-labeled antibody for in vivo use directed against tissue plasminogen activator demonstrating focal fibrinolytic activity. However, a major problem in immunoscintigraphy is the low signal-to-noise ratio due to circulating antibody. The hepatic clearance of t-PA is very rapid. The effect of a subsequent injection of a small amount of t-PA shortly after the antibody administration to increase the blood clearance rate of the formed antigen-antibody complexes was examined in six rabbits. More than 99% of the circulating antigen-antibody complexes were eliminated by the liver within 10 min. This technique could make immunoscintigraphy a first line diagnostic tool in acute medicine including imaging of thromboembolic lesions in organs with high blood volumes such as the lungs, the heart, and the brain.

Animals↗
PubMed1990

The role of fragment X polymers in the fibrin enhancement of tissue plasminogen activator-catalyzed plasmin formation.

When thrombin-mediated fibrin formation and tissue plasminogen activator (t-PA)-mediated fibrinolysis proceed in dynamic interaction, desA-(desB beta 1-42)-fragment X polymers are shown to be the predominant fibrin derivatives present during the rapid second phase of Glu1- and Lys78-plasminogen activation. To further investigate the effect of this intermediate, a method was developed for the production and purification of fibrinogen-derived desA-(desB beta 1-42)-fragment X, deprived of both COOH-terminal A alpha-chains, but still capable of thrombin-mediated polymerization. DesA-(desB beta 1-42)-fragment X polymer was compared to intact fibrin with regard to its stimulatory effect on Glu1-, Lys78-, and Val443-plasminogen activation, and its binding of Glu1- and Lys78-plasminogen. Pure fragment X polymer gave rise to a biphasic activation pattern like that of fibrin, demonstrating similar kinetics of rapid phase activation. The dissociation constant for the binding of plasminogen to the effector decreases by a factor of 14, and the stoichiometry increases by a factor of 2 upon plasmin-catalyzed cleavage of both native Glu1- to Lys78-plasminogen, and fibrin to fragment X polymer. We conclude that desA-fibrin protofibril formation is sufficient to initiate fibrin enhancement of t-PA-catalyzed plasminogen activation, and that optimal stimulation depends on further plasmin-mediated modification of the fibrin effector to desA-fragment X-related moieties. Optimal stimulation is dependent on the presence of the kringle 1-4 domains of plasminogen and probably results from altered and increased binding of both plasminogen and t-PA to the modified effector.

Amino Acid Sequence↗
PubMed1990

Analytical evaluation of a sensitive enzyme immunoassay for determinations of creatine kinase isoenzyme MB.

We have evaluated a new sensitive immunometric assay for the determination of creatine kinase (CK; EC 2.7.3.2) MB isoenzyme (NovoClone CK-MB), involving an enzyme label and two monoclonal antibodies directed against the B subunit and the M subunit, respectively. The anti-CK-B antibodies are bound to the solid phase. The assay was modified to be extremely sensitive and thus to measure the concentration range below and close to the cutoff value used for the diagnosis of myocardial infarction. A reference interval of 0-6 micrograms/L was found for 315 outpatients without myocardial diseases (132 men and 183 women); the overall median of the log-gaussian distribution was 1.91 micrograms/L (2.03 and 1.79 micrograms/L for men and women, respectively). Total and within-assay imprecision (CV) was less than 6% at the upper reference limit. The detection limit was 0.1 microgram/L. The assay provides a favorable signal-to-noise ratio: the calibrators 0.0, 2.0, and 30.0 micrograms/L give absorbances at 492 nm of 0.040, 0.140, and 1.600 A. respectively. We conclude that the assay provides biochemical identification of individuals with myocardial damage but without myocardial infarction.

Adolescent↗
PubMed1988

Kinetics of inhibition of tissue-type and urokinase-type plasminogen activator by plasminogen-activator inhibitor type 1 and type 2.

Highly purified plasminogen-activator inhibitors of type 1 (PAI-1) and type 2 (PAI-2), low-Mr form, were compared with respect to their kinetics of inhibition of tissue-type (t-PA) and urokinase-type plasminogen activator (u-PA). The time course of inhibition of plasminogen activator was studied under second-order or pseudo-first-order conditions. Residual enzyme activity was measured by the initial rate of hydrolysis of a chromogenic t-PA or u-PA substrate or by an immunosorbent assay for t-PA activity. PAI-1 rapidly reacted with single-chain t-PA as well as with two-chain forms of t-PA and u-PA. The second-order rate constant k for inhibition of single-chain t-PA (5.5 x 10(6) M-1 s-1) was about three times lower than k for inhibition of the two-chain activators. PAI-2 reacted slowly with single-chain t-PA, k = 4.6 x 10(3) M-1 s-1. The association rate was 26 times higher with two-chain t-PA and 435 times higher with two-chain u-PA. The k values for inhibition of single-chain t-PA, two-chain t-PA and two-chain u-PA were respectively, 1200, 150 and 8.5 times higher with PAI-1 than with PAI-2. The removal of the epidermal growth factor domain and the kringle domain from two-chain u-PA did not affect the kinetics of inhibition of the enzyme, suggesting that the C-terminal proteinase part of u-PA (B chain) is responsible for both the primary and the secondary interactions with PAI-1 and PAI-2. The k values for inhibition of single-chain t-PA and endogenous t-PA in plasma by PAI-1 or PAI-2 were identical indicating that t-PA in blood consists mainly in its single-chain form.

Glycoproteins↗
PubMed1988

Monoclonal antibodies against human angiotensinogen, their characterization and use in an angiotensinogen enzyme linked immunosorbent assay.

Monoclonal antibodies were produced against human angiotensinogen. An enzyme linked immunosorbent assay (ELISA) was developed using a high affinity monoclonal antibody as catching antibody and a polyclonal rabbit anti human angiotensinogen antibody as detecting antibody in a "sandwich" ELISA. Linear range of the ELISA was 15-450 pmol/l of human angiotensinogen. Intra- and inter- assay variation coefficients were in the range of 2% to 8%. A correlation coefficient, r = 0.97, (n = 20), with values obtained by radioimmunoassay. This correlation coefficient, obtained by using both normal and pregnant sera, confirmed that the ELISA fulfill the requirements for clinical useful assay. Characterization of the antibodies were performed with respect to affinity constant and epitopes.

Angiotensinogen↗
PubMed1988

Complement C5a receptor antagonism by protamine and poly-L-Arg on human leukocytes.

It is shown that protamine selectively and dose-dependently inhibits complement C5a-induced leukocyte responses such as histamine release from basophils, chemiluminescence and beta-glucuronidase release from neutrophils. Protamine produces parallel rightward displacements of the C5a dose-response curves. The inhibitory capacity of the polypeptide is reversible and disappears following repeated washing of exposed cells. In neutrophils poly-L-Arg similarly and specifically antagonizes C5a-induced chemiluminescence and enzyme release. This polymer alone, however, degranulates basophils and neutrophils, leading to histamine and enzyme release, respectively. It is concluded that on human neutrophils the arginine-rich polycations protamine and poly-L-Arg exhibit a competitive C5a receptor antagonism. In addition, protamine inhibits the C5a receptors on basophils. It is hypothesized that molecular conformations of the arginine-rich polycations might bind reversibly to, and block negatively charged groups at the C5a-receptor sites.

Basophils↗
PubMed1987

Plasminogen activator inhibitor-1 is the primary inhibitor of tissue-type plasminogen activator in pregnancy plasma.

The aim of the present work was to clarify to what extent plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2) contribute to the increase in plasma inhibition of tissue-type plasminogen activator (t-PA) observed during pregnancy. It was demonstrated that a monoclonal antibody against PAI-1 almost completely quenched inhibition of single-chain t-PA and most of the inhibition of two-chain t-PA in plasma during the third trimester of pregnancy. The remaining inhibition of two-chain t-PA was to a great extent abolished by a PAI-2 antibody. The second order rate constant (k1) for inhibition of single-chain t-PA by the inhibitor neutralized by the PAI-1 antibody was about 4.8.10(6) M-1.s-1. The conversion of single-chain t-PA to the two-chain form increased the reaction rate with the inhibitor about 3-fold. These kinetic data are comparable with those obtained with PAI-1 in non-pregnancy plasma or with purified PAI-1. From the above results it is concluded that PAI-1 is the primary inhibitor of both single-chain and two-chain t-PA and that PAI-2 is the secondary inhibitor of two-chain t-PA in pregnancy plasma. The concentration of reactive PAI-1 versus gestation age was assayed in plasma from 6 women by binding of PAI-1 to 125I-labelled single-chain t-PA followed by quantitation of the labelled t-PA-PAI-1 complex after separation by SDS-polyacrylamide gel electrophoresis.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1987

Immunochemical determination of acetylcholinesterase in amniotic fluid--an evaluation of eleven monoclonal antibodies.

Eleven monoclonal antibodies and a polyclonal rabbit antiserum were evaluated with respect to reactivity with acetylcholinesterase (AChE, EC 3.1.1.7) from erythrocytes and brain. Employing our enzyme antigen immunoassay for AChE five selected antibodies were evaluated with regard to their clinical usefulness in the prenatal diagnosis of neural tube defects (NTD). Of these, one antibody preferentially bound the enzyme from human brain, and discerned better than the others pathological samples (anencephaly, spina bifida and encephalocele) from normal ones. With this antibody no false positive values were obtained even if amniotic fluid samples were blood contaminated.

Acetylcholinesterase↗
PubMed1987

A sensitive solid-phase immunosorbent assay for tissue-type plasminogen activator activity in plasma using trinitrobenzoylated poly-D-lysine as a stimulator for plasminogen activation.

A sensitive, specific and precise immunosorbent assay for tissue-type plasminogen activator (t-PA) activity in plasma was developed. It measured the single-chain and the two-chain forms of t-PA with equal sensitivity. The assay involved (I) coating of wells in microtiter plates with a monoclonal antibody directed towards an epitope on t-PA apart from the catalytic active site, (II) binding of t-PA to the solid-phase antibody, (III) activation of plasminogen by antibody-bound t-PA in the presence of a new potent stimulator, trinitrobenzyl alkylated poly-D-lysine (TNB-poly-D-lysine) and measurement of plasmin activity with D-Val-Leu-Lys-pNA. Plasma samples were acid-treated and diluted 80 times in order to minimize the inhibitory effect of plasma on the assays. The assay could be performed within one working day with precoated microtiter plates. The sensitivity of the assay for t-PA in plasma was 1 pM (approximately 70 ng/l). The recoveries of single-chain and two-chain t-PA added to plasma was 97-104%. The intraassay coefficient of variation was 3.4-5.1% and the interassay coefficient of variation was 7.8-18%. Resting values of t-PA in plasma for 42 healthy subjects ranged between 0 and 30 pM (median: 4.1 pM). The values after 10 min venous occlusion ranged between 1.2 and 520 pM (median: 100 pM). The t-PA concentrations determined by the immunosorbent assay correlated well with euglobulin clot lysis time measurements (r = 0.940).

Antibodies↗
PubMed1986

Immunological relationship between the fast-acting plasminogen activator inhibitors from plasma, blood platelets and endothelial cells demonstrated with a monoclonal antibody against an inhibitor from placenta.

Two plasminogen activator inhibitors (I and II) were demonstrated in human placenta. The complex between inhibitor I and tissue-type plasminogen activator was purified by immunoadsorption to solid-phase anti-activator antibodies. The purified complex (Mr 95.000) was used for immunization of mice and subsequent production of monoclonal antibodies. One antibody (F37), which reacted with both free and complex-bound inhibitor I, was used for further study by a method involving binding of the antibody to protein A-Sepharose, immunoadsorption of antigen and analysis of the resulting supernatant by SDS-polyacrylamide gel electrophoresis and enzymography. The analysis showed that F37 reacted with the fast-acting plasminogen activator inhibitors recently demonstrated in plasma, blood platelets and endothelial cells, indicating that these inhibitors and inhibitor I share a common epitope. Inhibitor II did not react with F37. Inhibitor II is identical to the placenta inhibitor previously described by others. It reacted selectively with polyclonal antibodies against that inhibitor.

Antibodies, Monoclonal↗
PubMed1984

Native and degraded fibronectin: new immunological methods for distinction.

Two methods for quantitative determination of the high molecular weight glycoprotein, fibronectin, have been developed. Both methods are based on enzyme-linked immunoadsorbent (ELISA) techniques. In the first of the methods an antibody against fibronectin is used to trap the antigen. This double antibody technique can detect a slight decrease in the concentration of fibronectin stored for 5 days compared to the amount of fibronectin in the freshly purified preparation. In the second method, gelatin which is known to bind specifically to fibronectin, is used to catch fibronectin. By this method less than 1% of the fibronectin present in a freshly prepared preparation is measured after storage for 5 days. The results obtained with the two methods applied on a freshly prepared and a stored fibronectin are in agreement with sodium dodecylsulphate polyacrylamide gel electrophoresis followed by immunoblotting before and after gelatin-Sepharose adsorption. These techniques demonstrate that all the freshly prepared fibronectin adsorbs to gelatin-Sepharose, while stored fibronectin, which is broken down to numerous peptides, still reacts with the fibronectin antibody, but does not adsorb to gelatin-Sepharose. The two ELISA techniques were applied on amniotic fluid, cerebrospinal fluid and urine. The results indicated significant degradation of fibronectin in urine, and less degradation of fibronectin in amniotic and spinal fluid.

Amniotic Fluid↗
PubMed1984

Plasma and urine fibronectin concentration in kidney-transplanted patients.

Plasma and urine fibronectin concentration was determined by electroimmunoassay and ELISA-method in patients who received renal transplantation. The plasma fibronectin concentration decreased both after the transplantation, in relation to the acute rejection of the graft, and in the relation to immunosuppressive therapy. Urine fibronectin excretion increased in relation to the kidney transplantation and acute rejection of the graft. In association with improved kidney function, the urine fibronectin excretion decreased. It is suggested that it might be of clinical importance to determine the excretion of fibronectin into the urine in patients undergoing kidney transplantation.

Electrophoresis, Polyacrylamide Gel↗