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Biomedical subjects

R Lynen

Publications and source records attributed to R Lynen.

14 recordsLinked to original sources
PubMed1991

Characterization and quantification of anti-T in human serum using a reliable hemolysis test.

The need of fresh-frozen donor plasma with a low level of anti-T has been emphasized recently. Anti-T, as administered by transfusion of fresh-frozen plasma, has been accused repeatedly of enhancing hemolysis in septic children with T transformation of red cells. Therefore, a new hemolysis test for the quantification of anti-T in human serum has been developed. With our test, anti-T-poor plasma donors can be found. Additional results raise substantial doubt as to the pathogenetic role of anti-T in the development of the hemolytic-uremic syndrome, found in septic children with red-cell T transformation. It is impossible to predict in vivo hemolysis induced by anti-T knowing the temperature characteristics and the ionic conditions causing this antibody to mediate hemolysis in vitro. Obviously, T transformation itself plays the major pathogenetic role in these patients, and not the presence of anti-T. In the case of disseminated intravascular coagulation, a content of anti-T cannot be construed as prohibiting transfusion of fresh-frozen plasma to such patients.

Antibodies↗
PubMed1990

[Hemolytic-uremic syndrome in an adult with T-cryptantigen liberation].

Haemolytic uraemic syndrome was diagnosed in a 36-year-old woman with acute renal failure (creatinine 10.5 mg/dl), haemolytic anaemia (haemoglobin 9.7 g/dl, lactate dehydrogenase 1926 U/l) and thrombopenia (98,000/microliters). After initial plasmaphereses and high doses of furosemide all symptoms disappeared within three weeks. The lectin tests demonstrated that the illness was connected with the liberation of T-crypt-antigen (Thomsen-Friedenreich antigen) on the erythrocytes. This special form of the haemolytic uraemic syndrome (neuraminidase-induced haemolytic uraemic syndrome) has previously been observed almost exclusively in children. However, for diagnosis and differentiation of haemolytic uraemic syndromes the presence of liberated T-antigen on erythrocytes should also be tested for in adults.

Acute Kidney Injury↗
PubMed1990

Patients with anti-Vel--immunohematological characterization and transfusion management.

As reported by other authors we can confirm that the frequency of the blood group Vel negative in Lower Saxony is 1:4000. We report on a patient whose serological characteristics (IgM- and IgA-anti-Vel) made the transfusion of Vel positive blood impossible. Since it was not possible to obtain sufficient Vel negative red cell units in time, the patient was convinced to donate blood for autologous transfusions. This should be the procedure of first choice in the transfusion management of such patients.

Blood Group Antigens↗
PubMed1990

T and Tk transformation in hemolytic uremic syndromes.

In two cases of hemolytic uremic syndrome (HUS) the bacterial pathogenesis of the disease could be elucidated by lectin red cell agglutination tests. The possible role of anti-T and anti-Tk antibodies is discussed. Transfusions of fresh plasma had no adverse effects. The fatal outcome in one case was caused by disseminated intravascular coagulation (DIC).

Agglutination Tests↗
PubMed1989

Stages of anti-N-like immunization: a further contribution to problems arising from anti-N-like antibodies in hemodialysis patients.

In the past years, the discussion around problems arising from anti-N-like antibodies has waned in spite of their continuing existence. Even highly sophisticated rinsing procedures of dialysers after sterilisation with Formalin are not capable of preventing an anti-N-like immunization. Therefore, formalin sterilisation should no longer be employed. Three stages of the formalin-dependent anti-N-like immunization are described. Hematological and immunohematological problems in this patient group are documented.

Anemia↗
PubMed1976

Purification and some properties of factor D of the human properdin system.

Factor D has been purified by gel and ion exchange chromatographies, and by ultrafiltration through different membranes. The final preparation appeared pure in various analytical tests. The molecular weight of human D is 21,500 according to gel chromatography, the isoelectric point was found at pH 7.8. Factor D is an active esterolytic enzyme, it cleaves N-alpha-acetyl-L-lysine methyl ester and N-alpha-acetyl-L-glycyl-L-lysine methyl ester. Both peptide esters inhibit the hydrolytic activation of factor B by D in the presence of cobra venom factor. D is also inhibited by diisopropyl-fluorophosphate and by penylmethyl-sulfonyl-flouride.

Humans↗
PubMed1976

Purification of a human serum protein ("factor E") which enhances cobra venom factor-induced indirect lysis. Identification with the fifth component of complement.

Complexes formed of Cobra venom factor (CVF) and activated factor B (B) by interaction of CVF and B with trypsin or factor D are capable of activating the third and fifth complement component. When incubated with sheep or guinea pig red cells and guinea pig serum in the presence of EDTA, these CVFB complexes produce "indirect lysis". Addition of a human serum factor, earlier designated as factor E (6), greatly enhances the efficiency of this lytic system. The component with this activity has been purified to homogeneity (disc and immunoelectrophoresis). In chromatographic fractionations it was inseparable from the fifth complement component, it was inactivated by and reacted with several anti-C5 antisera, and kinetics of inactivation by heat (56 degrees C) and trypsin were the same for factor E and hemolytic C5 activities. It is concluded that factor E is the fifth component of human complement. Guinea pig C5 is not capable of supporting indirect lysis in a comparable manner, for as yet unknown reasons. Some possible explanations are discussed.

Animals↗
PubMed1975

Formation and composition of the C3 activating enzyme complex of the properdin system. Sequential assembly of its components on solid-phase trypsin-agarose.

An active C3 cleaving enzyme is generated when properdin factor B (glycine-rich beta-glycoprotein, GBG) is activated (GBG is cleaved) by factor D in the presence of C3b and Mg++. Factor D can be replaced by trypsin in this reaction but even then C3b and Mg++ are required. In the absence of C3b and/or Mg++ trypsin does not generate C3 cleaving activity from GBG although it cleaves GBG and releases its GGG fragment (B) under these conditions as well. Addition of C3b to GGG immediately after its release does not yield a C3 cleaving enzyme. These findings indicate that C3b, GBG and Mg++ interact, and that only in association with C3b can GBG be cleaved in a way that its enzyme activity, residing in a C3b, GGG complex, is expressed. The complex is labile (half-life at 20 degrees C: 9 minutes); Mg++ does not affect its stability nor is it essential for the activity. It was possible to sequentially fix on agarose the essential components of the C3 cleaving enzyme and thus to elucidate the single steps and the order of its formation. C3 was activated and the resulting C3b fragment fixed on agarose by incubating C3 with trypsin covalently bound to the agarose. The agarose-C3b intermediate was capable of binding GBG provided Mg++ was present. GBG could then be cleaved by factor D or trypsin added in solution; the solid-phase-fixed complex obtained had C3 cleaving activity, in the presence as well as absence of Mg++. Omission of any of these steps or components, or changes in the sequence did not give rise to an active enzyme. Mixtures of C3b, GBG and Mg++ have weak C3 cleaving activity by themselves. C3 cleavage in such incubation mixtures proceeds slowly for hours and is not accompanied by cleavage of GBG. There is thus complete analogy between the CVF-dependent and C3b-dependent C3 cleaving systems. C3b and CVF act in the same way, they form a reversible, weakly active C3 cleaving complex with GBG and Mg++, the activity of which is markedly enhanced but becomes subject to decay when GBG is cleaved by trypsin-like enzymes while bound to CVF or C3b.

Animals↗
PubMed1975

Cleavage of the third complement component (C3) and generation of the spasmogenic peptide, C3a, in human serum via the properdin pathway: demonstration of inhibitory as well as enhancing effects of epsilon-amino-caproic acid.

Human and guinea pig serum loses hemolytic activity of the third complement component (C3) during incubation at 37 degrees C. The loss is due to specific C3 cleavage involving the properdin system. This is concluded from the finding that C3 inactivation is prevented by EDTA, by elimination of properdin factor B, and unimpaired in C4 deficient guinea pig serum. In the presence of 1 M epsilon-amino-caproic acid (EACA) spontaneous C3 cleavage is considerably enhanced and accompanied by the appearance of biologically active C3a. Lower concentrations of EACA inhibit rather than enhance C3 cleavage in serum. The inhibitory effect of EACA is due to interference with the interaction of the properdin factors and their action on C3 as demonstrated in various systems: the assembly of an active C3-cleaving complex on zymosan, its regeneration after decay by factor D and factor B (GBG), cleavage of GBG by C3b and factor D in systems of purified components, and cleavage of C3 by preformed properdin complexes. Reactions involving the cobra venom factor were likewise depressed. In all these systems EACA was inhibitory even at 1M concentration. No single step in the development or action of an active properdin system was found to be enhanced by 1 M EACA. The enhancing effect of high concentrations of EACA on C3 cleavage in serum may be explained by its observed inhibition of C3b inactivator (C3bINA). This factor controls the properdin system by destroying C3b. In serum the inhibitory effect of 1 M EACA on C3bINA appears to allow escape of the properdin system from its control and thus to increase its net activity toward C3 despite inhibition of the enzymic reactions proper. At lower concentrations the effect of EACA on C3bINA is apparently less significant; therefore, at low concentrations of EACA, its inhibitory effects on C3 cleavage by the properdin system in serum prediominate.

Aminocaproates↗