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T Exner

Publications and source records attributed to T Exner.

At least 73 records · Page 4Linked to original sources
PubMed1983

Measurement of factor VIII CAg by immunoradiometric assay in human tissue extracts.

Samples of normal tissues taken from three patients within 24 hours of death were physically disrupted, washed and extracted. Centrifuged supernatants were tested for factor VIII coagulant antigen (VIII CAg) and factor VIII related antigen (VIII RAg) by radioimmunoassays using homologous and heterologous antisera respectively. VIII RAg was readily washed out by isotonic saline whereas VIII CAg required 1.5 M sodium chloride for optimal extraction from tissue homogenates. Highest levels of VIII CAg were detected in some lymph nodes followed by lung, liver and spleen. There was rapid loss of VIII CAg from most tissues in the absence of proteolytic inhibitors.

Antigens↗
PubMed1982

Contact activation by ellagic acid - the concept of soluble activator disputed.

Concentrated, true solutions of ellagic acid (EA) prepared by pH reduction had only a small effect on contact activation initially. However when the EA formed a fine microcrystalline dispersion there was concurrent development of contact activity with turbidity. The dependence of contact activity on EA concentration was found to be a log-log relationship. After relatively low speed centrifugation contact activity-promoting material was decreased from supernatant layers at all concentrations. These findings suggest that EA is not effective as a contact activator when in true solution, but is active only when present as a solid.

Benzopyrans↗
PubMed1980

Familial association of the lupus anticoagulant.

A lupus anticoagulant was detected in plasma from two pairs of siblings using the kaolin clotting time mixing test. Strong evidence for this inhibitor in one further sibling pair is presented. Although coagulation abnormalities are usually classified as either acquired or of genetic origin it is apparent that the lupus anticoagulant might often be an acquired coagulation defect requiring genetic predisposition.

Adolescent↗
PubMed1980

A micromethod for clotting tests and coagulation factor assays.

A simple microtechnique for carrying out partial thromboplastin time with kaolin tests with 2 microliter or less of test plasma is described. For single stage factor assays, less than 1 microliter of test solution may be used. Reagents and test plasma are loaded in sequence into a 10 microliter, long needle syringe and introduced into a micro test-tube immobilized in a water bath. The end-point is taken as a positive clearing of kaolin turbidity from the mixture while stirring. Correlation with normal techniques has been excellent.

Blood Coagulation Tests↗
PubMed1980

Comparison of thromboplastins used for oral anticoagulant control.

Prothrombin ratio (PR) ranges of 1.5-2.5 based on clinical effect are used for oral anticoagulant control with most commercially available thromboplastins, whereas with Australasian Reference Thromboplastin (ART) 2.0-3.5 is recommended. Plasmas from patients taking oral anticoagulants were concurrently tested with various thromboplastins and interrelationships between these products were determined. Although PR's with ART appear higher, in fact therapy based on ART guidelines is considerably more conservative than that monitored with most commercial thromboplastins.

Administration, Oral↗
PubMed1979

An evaluation of currently available methods for plasma fibrinogen.

Fibrinogen levels in a variety of clinical plasma samples were assessed concurrently by several methods. Technics that appeared to provide the best improvements over the basic varieties of methods for fibrinogen assay were used. Results were correlated against a reference method based on Ancrod clottable fibrinogen and calibrated by ultraviolet absorbance with alkaline solutions of carefully dried fibrin standard. The best correlations with the reference method were achieved by an immunologic method using the Centrifichem principle and by heat precipitation with quantitation by packing in microhematocrit tubes. A modified clot opacity method also gave acceptable results. The turbidimetric ammonium sulfate and sodium sulfite precipitation methods correlated less well with the reference method, and in particular, the sodium sulfite technic gave high apparent fibrinogen levels with jaundiced plasmas. Neither of the turbidimetric methods were useful for fibrinogen levels below 50 mg/dl. The thrombin time method showed excellent sensitivity to fibrinogen, even at very low fibrinogen levels, but did not correlate well with the reference method.

Ammonium Sulfate↗
PubMed1978

Apparent antihaemophilic activity of basic amphoteric polyelectrolytes.

Amphoteric polyelectrolytes with alkaline isoelectric points (for example Ampholine 9-11) intended for use in isoelectric focussing were found to shorten the prolonged partial thrombosplastin clotting time with kaolin (PTTK) of plasma deficient in factor VIII. The response of this PTTK to Ampholine 9-11 was linear when plotted on double log paper with a slope slightly greater than that of factor VIII itself. Ampholine 9-11 at 2% concentration had factor VIII and factor IX activity equal to that of normal plasma as well as somewhat less activity as factor XI. It had no significant correcting effect on the clotting of plasmas deficient in factors V, VII, X, II OR XII. Ampholine 9-11 inhibited low concentrations of contact activators and its effect in correcting factor VIII deficient plasma was found to be related to the degree of contact activation.

Amino Acids↗
PubMed1978

A sensitive test demonstrating lupus anticoagulant and its behavioural patterns.

The kaolin clotting time of platelet poor plasma was used as a sensitive test for detecting the lupus anticoagulant in mixtures of normal and patients' plasmas. Platelets were found to decrease the anticoagulant effect of a typical lupus inhibitor. Thus, high sensitivity in this test system was achieved by ensuring low platelet concentrations and omitting platelet lipid substitute. In 17 patients with disseminated lupus erythematosus (DLE), 12 had detectable inhibitor by this method, more than would be detected with routine coagulation tests. Mixing patterns were of four distinct types, representing three different modes of anticoagulant behaviour. The pattern (type 3) of plasma mixtures giving longer kaolin clotting times than the individual components could be reproduced in vitro by adding trace amounts of crude thrombin or platelet fragments to a more typical lupus anticoagulant-containing plasma; formation of such a mixing pattern by the plasma of a patient with DLE may therefore indicate activation of the coagulation pathway. Six patients with idopathic thrombocytopenic purpura (ITP) had no detectable inhibitor indicating that anti-platelet antibodies behave differently from the lupus anticoagulant.

Blood Cell Count↗
PubMed1977

Factor VIII deficient plasma for laboratory tests prepared from normal plasma and a human antibody.

Plasma from a patient factor VIII inhibitor was mixed at several low concentrations with fresh normal plasma. The factor VIII deficient plasmas obtained after a short incubation period were used as substrate plasmas in the normal one-stage factor VIII assay method. Results obtained using 0.5-1% of the inhibitor plasma in normal plasma compared favourably with those obtained using normal haemophilia A factor VIII deficient plasma provided that tests were carried out without delay. A single plasma exchange of this patient provided enough antibody to prepare more than 500 litres of factor VIII deficient plasma by simple mixing with fresh normal plasma.

Adult↗
PubMed1977

The activation of prothrombin complex concentrates by calcium in vitro.

The activation of prothrombin concentrate mixtures incubated "in vitro" was investigated. "Activation" was assessed by the correcting effect of suct mixtures on the APTT of a test plasma containing a factor VIII inhibitor and also by the generation of free thrombin. Thrombin itself was found to have insignificant activating effect. Prothrombin concentrates incubated with near-physiological levels of calcium appeared to correct the abnormal APTT to an increasing degree as the calcium concentration was increased. Free thrombin was generated with calcium cencentrations greater than those required for APTT correction. The activation process could be stopped at any stage by adding citrate which removed ionized calcium from the incubation mixture.

Blood Coagulation Tests↗
PubMed1976

Drop weight variation in an automated collection procedure and its relationship to apparent surface tension.

A drop counter-regulated fraction collector yields samples containing equal numbers of drops. Such fractions vary slightly in weight depending on experimental conditions such as surface tension. Provided that variables such as flow rate and eluate density remain constant, apparent surface tension may be estimated directly from the weights of eluate fractions obtained from gel filtration experiments. The detergents sodium cholate and sodium lauryl sulphate significantly decreased drop weights in this system. Following gel filtration on Sepharose 4B, sodium cholate eluted in the fractions containing low molecular weight material. It eluted in the same position when pre-mixed with human plasma. Normal plasma was found to contain two surface tension-reducing components with apparent molecular weights of 3-10(6) and 1-10(5). The apparent surface tension of whole human plasma was found to be time dependent and decreased as the flow rate was reduced.

Blood↗
PubMed1975

Haemoglobin Camperdown beta104(G6) arginine leads to serine.

Routine investigation of ante natal patients revealed a subtle change in the electrophoretic pattern on cellulose acetate of the proposita. Further investigations by isoelectric focussing in polyacrylamide gel suggested the presence of two major haemoglobin components. Using a modified cellulose acetate technique globin chain separation revealed an abnormal beta-chain. Chain separation on a carboxymethyl-cellulose column provided a pure sample of the abnormal beta-chain. After amino-ethylation, tryptic digestion and peptide mapping, amino acid analysis of relevant peptides showed the abnormality in the beta-chain to be a substitution of arginine by serine at the 104 position. The presence of a positively charged residue at this position would appear to be necessary for the stabilization of the haemoglobin central cavity. The replacement by serine in this haemoglobin leads to slightly decreased stability but does not appear to affect the oxygen affinity.

Adult↗
PubMed1975

Fibrin powder turbidity measurement for rapid assessment of antiplasmins.

Fibrinolytic activity was determined from the rate of disappearance of turbidity in a suspension of heat-treated fibrin powder. Using this method for estimating residual fibrinolytic activity in mixtures of serum and plasmin, antiplasmin behaviors of specimens from patients with various clinical disorders were determined after long and short preincubation times. Slow-acting antiplasmins were found to be increased in a variety of conditions among these patients, while immediate acting antiplasmins were generally decreased, compared with those in specimens from a large pool of normal, healthy vounteers. Normal women taking oral contraceptives had consitently high levels of slow antiplasmins. Tests in vitro showed that the antifibrinolytic agents epsilon-aminocaproic acid, Trasylol and soybean trypsin inhibitor act only as fast antiplasmins.

Aminocaproates↗