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Biomedical subjects

A Z Budzynski

Publications and source records attributed to A Z Budzynski.

At least 55 records · Page 3Linked to original sources
PubMed1984

Fibrinogenolytic afibrinogenemia after envenomation by western diamondback rattlesnake (Crotalus atrox).

The absence of fibrinogen and the presence of plasmic fragments X, Y, D, and E were demonstrated in a patient bitten by a western diamondback rattlesnake, Crotalus atrox. The factor VIII level and the platelet count were within normal limits. There were distinct changes of protease inhibitors in the patient's plasma. Alpha-1-protease inhibitor was elevated. Antithrombin-III was only slightly decreased after the envenomation, but alpha 2-antiplasmin and alpha 2-macroglobulin were initially significantly lowered, returning to normal values in 38 and 3 days, respectively. Plasmin-alpha 2-antiplasmin complex was present until day 10 after the envenomation. However, purified plasminogen was not activated in vitro by the venom. Cultured endothelial and smooth muscle cells from human blood vessels released an increased amount of plasminogen activator upon incubation with the venom. The release did not result from cell lysis. Platelets in normal human platelet-rich plasma were aggregated by 10 micrograms/ml of the venom, without serotonin secretion. The aggregation kinetics and serotonin secretion induced by adenosine diphosphate (ADP) or arachidonate were not significantly affected by the venom at 1-10 micrograms/ml. It is concluded that the predominant mechanism of afibrinogenemia in the patient after Crotalus atrox bite resulted from primary fibrinogenolysis and not from a consumptive coagulopathy. The lytic state seemed to be induced through an indirect activation of plasminogen by vascular plasminogen activator, which was probably released from endothelial cells and smooth muscle cells by the snake venom.

Adult↗
PubMed1983

Fibrinogen interaction with platelet receptors.

In summary: Incubation of platelets with ADP or proteolytic enzymes (chymotrypsin or pronase) results in an exposure of two classes of specific binding sites on platelet surface: low and high affinity fibrinogen receptors. Fibrinogen interaction with these receptors results in platelet aggregation. High affinity fibrinogen receptors are not exposed on thrombasthenic platelets stimulated by ADP but are rendered available on chymotrypsin-treated thrombasthenic platelets; low affinity receptors cannot be exposed by ADP or chymotrypsin on these platelets. Availability of high affinity fibrinogen receptors on thrombasthenic platelets may depend on the residual glycoprotein IIIa. Fibrinogen receptors appear to be associated with glycoproteins IIb, IIIa and a 66,000 Mr platelet membrane component that is exposed during proteolysis of platelet membranes. Some of the platelet-binding sites on the fibrinogen molecule appear to be associated with the COOH-terminal portion of the gamma chain (gamma 374-411). Additional binding sites may also be located in the COOH-terminal portion of the A alpha chain. The conformation of the fibrinogen molecule may be important in its interaction with platelets. Platelet aggregation may result from bridging platelets by fibrinogen molecule in the presence of bivalent cations. In conclusion, platelet interaction with fibrinogen is a complex process involving different binding sites of the fibrinogen molecule. Our own data and review of literature suggest that platelet-interaction with fibrinogen is of major significance in hemostasis.

Adenosine Diphosphate↗
PubMed1983

Unique degradation of human fibrinogen by proteases from western diamondback rattlesnake (Crotalus atrox) venom.

Thrombin-coagulability of both human fibrinogen and plasma was rapidly lost upon incubation with western diamondback rattlesnake (Crotalus atrox) venom. The dose- and time-dependent effect was due to direct proteolytic degradation of fibrinogen (Mr 340,000) by venom enzymes. Using purified fibrinogen as the substrate it was demonstrated that the venom degraded the A alpha chain first and then the B beta chain. The degradation pattern of fibrinogen in plasma was different to that of purified fibrinogen, since only the B beta chain was cleaved. A fibrinogen derivative isolated from venom-treated plasma had impaired thrombin-coagulability, Mr 325,000 +/- 10,000, its A alpha and gamma chains appeared intact and only the B beta chain was degraded to a species of Mr 52,000 +/- 1,500. The venom contained three proteolytic enzyme fractions as revealed by gel filtration chromatography. All abolished coagulability of purified fibrinogen, however, only one enzyme fraction rendered plasma incoagulable. The proteolytic enzyme with anticoagulant activity against plasma degraded only the B beta chain of purified fibrinogen, generating a derivative of Mr 325,000, which was identical to that obtained upon incubation of the crude venom with plasma. The polypeptide chain structure of the derivative indicates that the intact B beta chain of fibrinogen plays an important role in the formation of fibrin clots.

Anticoagulants↗
PubMed1983

Specific uptake of radioiodinated fragment E1 by venous thrombi in pigs.

Fragment E1, a product of plasmic digestion of cross-linked fibrin, binds specifically in vitro to polymerized fibrin but not to fibrinogen. Purified human Fragment E1 was radiolabeled with 125I or 131I by the Iodogen technique. The uptake of radioiodinated Fragment E1 in vitro into forming or preformed clots was demonstrated. Animal biodistribution studies of radioiodinated Fragment E1 showed its rapid removal from the circulation; radioactive catabolites did not reside long in any organ and were excreted in the urine. The uptake in vivo was evaluated in pigs with preexisting venous thrombi of various ages from 1 h up to 5 d at the time of intravenous systemic injection of the tracer. Radioiodinated fibrinogen was also injected into the same animals to compare the uptake of the two tracers. Thrombus-to-blood ratios for Fragment E1 averaged 43:1 (range 10-108) and 29:1 (range 8-107) in thrombi 1-6 h and 1-5 d old, respectively. In contrast, mean thrombus-to-blood ratios for fibrinogen were, in the same time intervals, 26:1 (range 17-41) and 2:1 (range 0.5-3.9), respectively. It is concluded that radioiodinated Fragment E1 is a specific marker of thrombi in vivo: its uptake by fresh thrombi is better than that of labeled fibrinogen and, in contrast to radioiodinated fibrinogen, this fragment is incorporated into old thrombi as well.

Animals↗
PubMed1983

Congenital hypofibrinogenemia and recurrent placental abruption.

A 32-year-old white woman with a history of 2 episodes of abruptio placentae was found to have congenital hypofibrinogenemia. She had no bleeding difficulties except when pregnant. The patient's sisters and her mother also had reduced fibrinogen levels. Results of fibrinogen measurement by clotting assays and immunologic studies were similar. Immunoelectrophoresis, molecular weight of fibrinogen chains, cross-linking by factor XIII, carbohydrate staining, and sialic acid quantitation were all normal, suggesting the diagnosis of hypofibrinogenemia rather than dysfibrinogenemia. Fibrinolysis did not account for the reduced fibrinogen level. This case demonstrates that congenital low fibrinogen levels may be associated with placental abruption and that an abnormal fibrinogen molecule is not necessary.

Abruptio Placentae↗
PubMed1983

Inhibition of lung tumor colonization by leech salivary gland extracts from Haementeria ghilianii.

Salivary gland extract from the South American leech Haementeria ghilianii, administered i.v. on the same day as the i.v. inoculation of T241 sarcoma cells, completely suppresses colonization of the mediastinal lymph nodes and markedly reduces the number and size of lung tumor colonies produced by this tumor. Additional studies indicate that the extract contains various types of proteinase inhibitors and has the capacity to inhibit clotting and platelet aggregation by tumor material and collagen. Although not yet proved by direct evidence, these activities may be involved in the inhibitory effect of lung tumor colonization by the leech extract.

Animals↗
PubMed1981

Structure of fragment E species from human cross-linked fibrin.

Fragments E1, E2, and E3 are plasmic derivatives of fibrin encompassing the NH2-terminal region of the molecule. The first two species, but not the third, can bind to fragment DD, forming a (DD)E complex, and therefore probably contain binding sites involved in the polymerization of fibrin. For localization of these sites the structure of the fragments was determined by establishing the NH2- and COOH-terminal boundaries of the molecules and using the published amino acid sequence of fibrinogen. Fragment E1 encompasses Gly-alpha 17 to Lys-alpha 78, Gly-beta 15 to Lys-beta 122, and Tyr-gamma 1 to Lys-gamma 62, this representing the intact NH2-terminal region of fibrin. Fragment E2 is an asymmetric molecule which is lacking the sequence of Gly-beta 15 to Lys-beta 53 in one beta-chain remnant. This fragment E2 also lost Lys-beta 122 from the COOH terminal of the beta chain as compared with fragment E1. These cleavages did not affect the ability of fragment E2 to bind to fragment DD. Fragment E3 was heterogeneous, the main species encompassing Val-alpha 20 to Lys-alpha 78, Lys-beta 54 to Leu-beta 120, and Tyr-gamma 1 to Lys-gamma 53. Thus, the loss of the binding function involved in the formation of fibrin clot was associated with the removal of small fragments from all three polypeptide chains: alpha 17-19 (Gly-Pro-Arg), beta 15-53 from the remaining half of the molecule, beta 121 (Leu), and gamma 54-58 (Thr-Ser-Glu-Val-Lys).

Amino Acid Sequence↗
PubMed1981

Localization of a fibrin polymerization site.

The formation of a fibrin clot is initiated after the proteolytic cleavage of fibrinogen by thrombin. The enzyme removes fibrinopeptides A and B and generates fibrin monomer which spontaneously polymerizes. Polymerization appears to occur though the interaction of complementary binding sites on the NH2-terminal and COOH-terminal (Fragment D) regions of the molecule. A peptide has been isolated from the gamma chain remnant of fibrinogen Fragment D1 which has the ability to bind to the NH2-terminal region of fibrinogen as well as to inhibit fibrin monomer polymerization. The peptide reduces the maximum rate and extent of the polymerization of thrombin or batroxobin fibrin monomer and increases the lag time. The D1 peptide does not interact with disulfide knot, fibrinogen, or Fragment D1, but it binds to thrombin-treated disulfide knot with a Kd of 1.45 X 10(-6) M at approximately two binding sites per molecule of disulfide knot. Fibrin monomer formed either by thrombin or batroxobin binds approximately two molecules of D1 peptide per molecule of fibrin monomer, indicating that the complementary site is revealed by the loss of fibrinopeptide A. The NH2-terminal sequence (Thr-Arg-Trp) and COOH-terminal sequence (Ala-Gly-Asp-Val) of the D1 peptide were determined. Therefore the gamma 373-410 region of fibrinogen contains a polymerization site which is complementary to the thrombin-activated site on the NH2-terminal region of fibrinogen.

Amino Acids↗
PubMed1981

Radiolabeling of fibrinogen using the iodogen technique.

The properties of human fibrinogen labeled with 125-Iodine using Iodogen (1, 3, 4, 6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril) as an oxidizing agent were compared with those of an iodine monochloride labeled counterpart. It was found that thrombin clottability, binding to staphylococci, the relative specific radioactivity of the A alpha, B beta, and gamma chains and in vivo clearance from plasma in rabbits were the same in these two labeled fibrinogen preparations. Labeling efficiency was higher when iodogen was used. It is concluded that human fibrinogen labeled with radioiodine using the Iodogen technique is suitable for studies in vitro and in vivo.

Animals↗
PubMed1980

Effects of fibrinopeptide cleavage on the plasmic degradation pathways of human cross-linked fibrin.

The presence of fibrinopeptide B in human fibrin has a significant effect on plasmic degradation pathways of cross-linked clots. Two types of fibrin were obtained from fibrinogen by incubation either with thrombin, to remove both fibrinopeptides A and B, or with batroxobin, to cleave fibrinopepitde A only. Fibrins obtained after various incubation times were characterized by the determination of the NH2-terminal amino acids, the content of fibrinopeptides, and the extent of cross-linking. The fibrins were digested by plasmin and were analyzed by polyacrylamide gel electrophoresis. The presence and concentration of the (DD)E complex, as well as fragments E1 and E2, in the digests were dependent upon the loss of fibrinopeptide B from cross-linked fibrin. These degradation products, and also fragment DD, appear to be useful molecular markers of fibrinolysis.

Amino Acids↗
PubMed1980

Evidence for four different polymerization sites involved in human fibrin formation.

The mechanism of association and the organization of human fibrin were studied by using affinity chromatography. Insolubilized fibrinogen, fibrin monomer, and crosslinked fibrin were used to localize the binding sites on fibrinogen and fibrin derivatives. Four different polymerization sites have been distinguished. A binding site ("a"), available without thrombin action, is present on the fibrinogen fragment D domain. The complementary ("A") is inoperative in fibrinogen and requires thrombin for activation; it is located on the fibrinogen NH2-terminal domain. A third polymerization site ("b") appears to be formed by the alignment of the fragment D domains on two fibrin monomer molecules upon polymerization; this site functions without thrombin mediation and the alignment is stabilized by the Factor XIIIa-catalyzed crosslink bonds. The "b" site is complementary to another thrombin-activated site ("B") on the fibrinogen NH2-terminal domain. The two thrombin activable sites, "A" and "B", are distinguishable, although they are located in the same fibrinogen domain.

Binding Sites↗
PubMed1979

Binding phenomena of isolated unique plasmic degradation products of human cross-linked fibrin.

Proteolysis of human cross-linked fibrin by plasmin results in the formation of a DD . E complex, and Fragments DD and E as the major degradation products. Three species of Fragment E, which differ both in molecular weights (E1, Mr = 60,000; E2, Mr = 55,000; E3, Mr = 50,000) and in charge, have been isolated from a digest of cross-linked fibrin. Each Fragment E species reacts with monospecific anti-E antiserum. Fragments E1 and E2 bind with Fragment DD to form a DD . E complex but Fragment E3 is inactive. This binding is specific since these Fragments E do not bind to fibrinogen or to degradation products of fibrinogen or of noncross-linked fibrin. Fragments E1 and E2 incubated with plasmin are degraded to Fragment E3, suggesting that the three species represent sequential degradation products. Plasmin-treated Fragments E1 and E2 no longer bind with Fragment DD; therefore, it appears that the peptides cleaved from Fragment E2 by plasmin contain or modify the sites responsible for complex formation. On the other hand, Fragment DD binds not only to Fragments E1 and E2, but also to fibrinogen, Fragments X (Stage 1), X (Stage 2), Y, and NH2-terminal disulfide knot, but only after thrombin treatment, suggesting that Fragment DD binds to complementary sites on the NH2-terminal region of fibrinogen which are exposed after thrombin treatment.

Drug Stability↗
PubMed1979

The interference of plasmic degradation products of human crosslinked fibrin with clot formation.

The role of plasmic degradation products of human crosslinked fibrin on polymerization of fibrin monomer and clot formation was studied. Both reactions were inhibited by Fragment DD, which formed a complex with fibrin monomer in a molar ratio 1 : 1. The rate of polymerization was slightly increased by Fragment E but it was not affected by (DD)E complex and Fragment A. Approximately the same amount of fibrin was formed in the presence and absence of Fragments A, E and the complex. It was concluded that of the degradation products of crosslinked fibrin, only Fragment DD is a potent anticoagulant at physiologic pH. The (DD)E complex is inert and Fragments A and E have only marginal effects.

Blood Coagulation↗