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Biomedical subjects

B Hessel

Publications and source records attributed to B Hessel.

At least 37 records · Page 2Linked to original sources
PubMed1985

FXIII induced gelation of human fibrinogen--an alternative thiol enhanced, thrombin independent pathway.

Factor XIII induced gelation of human fibrinogen in the presence of calcium ions. At the end of this reaction between 95 and 100% of the fibrinogen was incorporated into the gel matrix. The gelation was dramatically enhanced by DTT. Cysteine and beta-mercaptoethanol also enhanced the reaction, but less efficiently. Thrombin activated factor XIII led to shortened gelation time and increased the rate of gelation. The reaction was inhibited by p-chloromercuribenzoate and iodoacetamide. Neither fibrinopeptide A, nor fibrinopeptide B were released during gelation, while quantitative release of FPA by thrombin was demonstrated from preformed gel matrices. SDS-PAGE showed the presence of gamma-dimers and alpha-polymers in the gel matrix. In the clot supernatants gamma-dimers were observed already before the gel point. We also observed that the clotting of fibrinogen by thrombin was perturbed by DTT. Preincubation of fibrinogen with calcium ions prevented this effect of DTT.

Calcium↗
PubMed1984

Structure-function relationships of human factor VIII complex studied by thioredoxin dependent disulfide reduction.

A highly purified, multimeric factor VIII complex composed of VIII: vWF and some factor VIII: C contained about 100 disulfides per subunit of Mr 260,000. Limited reduction of disulfide bonds in this complex by NADPH, thioredoxin reductase and thioredoxin leads to partial disaggregation of the multimeric VIII:vWF with concomitant loss of its platelet agglutinating activity in the presence of ristocetin, and with dissociation of factor VIII:C from the complex. During this event, no Mr 260,000 subunit of VIII:vWF is discernible. However, prolonged reduction results in the appearance of different multimers, and of some Mr 260,000 subunits. An N-terminal amino acid sequence for VIII:vWF was deduced. Two half-cystine residues in this sequence were shown to be involved in the reaction with thioredoxin. It appears possible that the thioredoxin system or other redox systems may play a role in regulation of factor VIII activities and of hemostatic processes in vivo.

Amino Acid Sequence↗
PubMed1983

Influence of fibrinogen fragments on human lymphocyte thymidine uptake.

Fragments of human fibrinogen were tested for ability to suppress activation of human blood lymphocytes by the lectin phytohaemagglutinin (PHA). Measurement of cellular 14C-thymidine uptake was used as an indicator of DNA synthesis and cell proliferation. The tested fragments were obtained by plasmin digestion or by CNBr fragmentation of fibrinogen. Inhibition of uptake, with good dose response relationship, was demonstrated for the plasmic fragment PL-3 and for the CNBr fragment Hol-DSK. Digests of the latter with trypsin and plasmin gave the same effects as the intact fragment. However, reproducibility was poor with PL-3. Hol-DSK gave better reproducibility, but with pronounced interbatch variations. Other fragments of fibrinogen were tested, but gave no effect in the studied concentrations. The reason for the poor reproducibility is discussed.

Chromatography, Gel↗
PubMed1983

Effects of fibrinogen fragment and proteolytic enzyme on the immune system in mice.

The immunomodulating ability of fibrinogen fragment (Hol-DSK) and proteolytic enzyme with fibrinolytic activity from Aspergillus oryzae was analysed in CBA/Ca, C57Bl, C3H/HeJ and NMRI mice. Suppressive effects on the blastogenic response to mitogens were noted. No consistent suppressive effect, but sometimes an enhancing one, was recorded on the antibody responses to protein antigens. Administration of Hol-DSK or proteolytic enzyme shortly after the immunization resulted in a slight inhibition of the development of delayed hypersensitivity to picryl chloride in C57Bl but not in CBA mice. When similar administration was done simultaneously with administration of the challenging antigen of picryl chloride or sheep red blood cells in immunized mice, significant impairment of the delayed-type hypersensitivity reaction was noted. The modulating effects by Hol-DSK did not alter the in vitro bacteriocidal effects of peritoneal exudate cells from mice on Escherichia coli.

Animals↗
PubMed1982

Measurement in human blood of fibrinogen/fibrin fragments containing the B beta 15-42 sequence.

This paper describes a radioimmunoassay for the B beta 15-42 peptide derived from human fibrinogen or fibrin. Iodinated B beta 15-42 is bound by specific antiserum and binding can be completely inhibited by excess of the non-iodinated B beta 15-42, B beta 1-42 or B beta 1-118. These peptides cannot be distinguished in this assay. Furthermore, fibrinogen can also completely inhibit binding of iodinated B beta 15-42 peptide. Due to the cross-reaction with fibrinogen, clinical blood samples require a processing step prior to their use in this radioimmunoassay. Ethanol precipitation allows for fibrinogen removal and a near quantitative recovery of both added B beta 15-42 peptide as well as of the endogenous blood peptide(s) containing the B beta 15-42 sequence. The mean level of B beta 15-42 immunoreactive material in normal individuals was found to be 0.41 pmol/ml while that in one group of patients was 20-40 times this value.

Adult↗
PubMed1981

Binding of fibrinogen degradation products to S. aureus and to beta-hemolytic streptococci group A, C and G.

Binding of fibrinogen degradation products was measured to Gram-positive cocci known to carry receptors for human fibrinogen. Forty-one strains of S. aureus and group A, C and G streptococci were studied. The largest plasmin produced fragment (X-fragment, HMWDP) showed higher binding levels to the bacterial receptors in all four species as compared to intact fibrinogens. The enzymatically produced C-terminal fragment D was strongly reactive, whereas the N-terminal fragment E was non-reactive. Inhibition experiments showed that reactive fragments were bound to the same receptors as fibrinogen. Three chemically-produced and well-characterized fragments from the terminal and the middle portions of the fibrinogen molecule were all negative in binding assays. The binding patterns for fibrinogen and the fragments tested were identical in the four bacterial species tested, S. aureus and group A, C and G streptococci. The results confirm and extend earlier data on similarities between fibrinogen receptors on these Gram-positive bacterial species.

Binding Sites↗
PubMed1979

Primary structure of human fibrinogen and fibrin. Structural studies on NH2-terminal part of B beta chain.

The cyanogen bromide fragment, N-DSK, containing the NH2-terminal portions of the three chains of fibrinogen, was found to exist in dimeric and polymeric forms. These different forms gave rise to identical chain fragments on reduction and alkylation. The B beta chain of N-DSK from fibrinogen and the beta chain of N-DSK from fibrin were isolated and characterized. The B beta chain fragment has a blocked NH2-terminal residue, and fibrinopeptide B is released on digestion with thrombin. The beta chain fragment has glycine as NH2-terminal residue. The molecular weight of the B beta chain fragment is 12200 as determined by ultracentrifugal analysis. Gel electrophoresis in sodium dodecyl sulphate gave the molecular weights of 14000 and 13000 for the B beta chain and beta chain fragments, respectively. The NH2-terminal B beta chain fragment consists of 118 amino acid residues and the beta chain fragment of 104 residues. The amino acid sequence of beta chain fragment is identical to B beta chain fragment except for the fibrinopeptide B portion. The isolation of a B beta-related fragment (B beta +), with a molecular weight of 30000, is also reported. The presence of B beta + was explained on the basis of incomplete cleavage at the Met-118 residue during treatment with cyanogen bromide. Some functional aspects of the B beta chain fragment are discussed.

Amino Acid Sequence↗
PubMed1978

A two-step fibrinogen--fibrin transition in blood coagulation.

The kinetics of the thrombin-catalysed release of fibrino-peptides A and B from human fibrinogen have been investigated and a mechanism correlating the release of fibrinopeptides to fibrin formation is presented. The sequential release of fibrinopeptides results in sequential activation of two sets of polymerisation sites.

Binding Sites↗
PubMed1978

[Fibrinogen: structure, function and interaction with proteins and cells].

The dimerous three-chained protein fibrinogen has at its disposal different functional zones which are included in the process of polymerisation and which possess importance for the specific reaction of fibrinogen with certain cells. The present paper is particularly engaged with the activation of fibrinogen by thrombin and with the mechanism of the arrangement of the activated units of fibrinogen concerning the fibrin fibre. Finding concerning the interaction of the platelets with fibrinogen connected to sepharose plead for the fact that a change of conformation in the molecule of fibrinogen precedes the specific platelet reaction.

Blood Platelets↗
PubMed1978

Photooxidation of fibrinogen in the presence of methylene blue and its effect on polymerization.

Human fibrinogen was illuminated in the presence of methylene blue. The resulting photooxidized fibrinogen was devoid of polymerization activity and thrombin-induced coagulability. The initial rate of the thrombin catalysed release of fibrinopeptides from photooxidized fibrinogen was normal. It was shown that illumination of photooxidized fibrinogen and photooxidized fragment N-DSK caused the modification of histidine residues. Tryptophan residues were also modified. When fibrinogen was photooxidized immediately after the addition of thrombin, the capacity to polymerize was lost. The inhibition of polymerization was less marked when oxidation was initiated at the time when polymerization began or thereafter. Photooxidized fibrinogen acts as an inhibitor of the polymerization of fibrin monomers. Photooxidized fibrinogen has affinity for thrombin-activated fibrinogen-Sepharose and thrombin-activated fragment N-DSK-Sepharose. When the former conjugate is illuminated in the presence of methylene blue its affinity for fibrinogen is decreased. It is concluded that the fragment N-DSK domain of fibrinogen is affected by photooxidation.

Amino Acids↗