Altmetrics, webometrics and informetrics as the complementary vectors in the modern bibliometrics

Modern practical experience in bibliometrics is based on the scrupulous study of researchers’ performance on the Internet. Most of the Russian scientists are confused by an array of indicators, and are unable to assess their own level of influence on modern science. The dynamic and successful development of science and related scientific and research activities throughout the twentieth century has revealed the vital problem of measuring the effects (impacts) of research findings. Participating in the academic life, the researchers have to evaluate constantly themselves and the colleagues in terms of assessing individual and collective contribution and using "digital" scientometrical indicators. The author reviews the modern perception of the significance and role of "digital" indicators in scientometrics on the whole, and in bibliometrics, in particular, in assessing modern science and its findings. While such indicators as Hirsch index, impact factor of scientific publications are the widely-known indicators, and Eigenfactor (native factor) is familiar to the few, almost no one knows what altmetrics and informetrics are and how to apply them. This article will make the first work in the series on the practical aspects of applying "digital" bibliometrical indicators in the daily researcher’s routine.

FLUORESCENCE STUDIES OF THE BINDING OF FACTOR Va TO PHOSPHOLIPID VESICLES

The free sulphydryl groups in factor Va were analyzed under native and denaturing conditions using dithio-bis-nitrobenzoic acid (DTNB). The heavy chain (D) and the light chain (E) of factor Va were found to contain one free sulphydryl each under native conditions and following denaturation. Intact factor Va contained two free sulphydryls after denaturation while only one of these groups was accessible to DTNB under native conditions. Analysis of the rates of modification of the accessible sulphydryl in factor Va, and direct visualization of factor Va reacted with fluorescent sulphydryl modifiers and analyzed by SDS-PAGE, indicated that the accessible group was present in component D. Factor Va was labelled with the sulphydryl-directed flurophore N-pyrene-l-malemide with no loss in functional activity. Fluorescently modified Va (PYR-Va) contained between 0.83 and 0.91 moles pyrene and showed a concomittant loss in the free sulphydryls accessible to DTNB. Fluorescence polarization studies indicated that the binding of PYR-Va to phospholipid vessicles composed of phosphatidylcholine (PC) and phosphatidylserine (PS) was accompanied by a significant increase in the fluorescence polarization of the pyrene moiety. Systematic analysis of the binding of PYR-Va to PCPS (75%PC, 25%PS) indicated that the binding interaction was characterized by a Kd=2.7x10−9 M and a stoichiometry of 42 monomeric phospholipids per lipid combining site. The binding of PYR-Va to PCPS was independent of added calcium ion and could be reversed by the addition of unlabelled factor Va. Analysis of the displacement curves indicated that native factor Va and PYR-Va mutually excluded each other with identical affinities (Kd=2.5×10−9 M). Isolated component D had no effect on the interaction between PYR-Va and PCPS, while isolated component E was capable of disrupting the PYR-Va-PCPS interaction (Kd=3.1×10−9 M%) indicating that this subunit entirely mediates the interaction between Va and PCPS. No detectable binding of PYR-Va was observed when 100% PC vesicles were used and systematic variation of the PS content of the vesicles indicated that this parameter linearly influenced the stoichiometry of the PYR-Va-PCPS interaction with a minimal effect on the dissociation constant for the reaction. The data indicate that the factor Va-binding site is determined by the PS content of the lipid bilayer.(Supported by NIH grants HL-35058 and HL-34575)

THE ROLE OF THE CARBOHYDRATE MOIETY OF HUMAN FACTOR V IN COAGULATION AND TURNOVER

The importance of the carbohydrate moiety of the human coagulation factor V molecule was investigated by its desialation and deglycosylation. Upon removal of 90% of the sialic acid residues a 1.5-2 fold increase in clotting activity was observed. Whereas up to 70% deglycosylation resulted in a parallel decrease in clotting activity. Thrombin induced activation of desiala-ted factor V was unchanged, whereas deglycosylated factor V activation was impaired. The importance of the carbohydrate structure was further established by lectin incubation experiments. The distribution of carbohydrate in the thrombin induced activation fragments of factor V was investigated in lectin blot experiments with sialic acid-specific LFA, galactose-specific RCA-II and mannose-specific Con A. Carbohydrate residues were demonstrated in fragments B, C1, D and F1F2 . Interestingly, sialic acid was demonstrated in C1, But galactose could not be shown. In fragment F1F2 ultimate galactose residues were found. The relevance of the carbohydrate moiety was further established by turnover experiments of native and desialated human factor V in rabbits. In contrast to the native factor V, desialated factor V was instantaneously cleared from the circulation.In summary, these findings indicate an important role for the carbohydrate moiety in human coagulation factor V.

Complement-Dependent Activation Of Plasminogen By Activated Factor B (Bb) Of The Alternative Pathway Of Complement

Activated Factor B (Bb) of the alternative pathway of complement (APC) induces human monocytes and murine macrophages to spread on a glass substrate (Sundsmo and Gątze (1980), Cell. Immunol., 52:1). In studies designed to investigate the effects of Bb on plasminogen activator secretion by human monocytes, it became apparent that Bb possesses innate plasminogen activator (PA) activity. PA activity of Factor Bb was determined by release of radiolabeled fibrin peptides (modified fibrin plate assay) over 4 hrs. at 37°C using purified human plasminogen, 125I-labeled human fibrinogen, and 20% fresh normal human serum as a source of thrombin. Native Factor B did not express significant PA activity, however, purified Bb, or Bb in complex with cobra venom factor released, 52±8% and 79±4%, respectively, of the 125I- fibrin that is released by urokinase. Intermediate complement complexes on rabbit erythrocytes (Er) were tested for their PA activity: ErC3b, Bb released 76±7% of 125I-fibrin, and control Er, C3, and B released <15%. Factor D was without activity. Cleavage of plasminogen by Factor B was investigated by incubating cellular complement intermediates (ErC3b, Bb; EsC3b, Bb, NF) 30 min./37°C with 125iI-labeled plasminogen; and, conducting SDS-PAGE (reducing conditions) to separate native plasminogen from the heavy and light chains of plasmin. It was found that Bb cleaves predominantly the Lys-form of plasminogen to generate fragments with apparent molecular weights of 72,000 and 30,000. As a control, 125I-labeled plasminogen was incubated with Er, C3, or D, and <10% cleavage was observed; EsC3b or native Factor B cleaved <5%. Affinity-purified goat anti-B Ig inhibited Factor Bb- dependent plasminogen cleavage by 99%. These results suggest that activated Factor B, the central serine esterase of the APC, can serve as a plasminogen activator and raise the possibility that Factor B may play a role in initiation of fibrinolysis as well as in complement-dependent humoral and cellular mechanisms of immunity.

Surface Adsorption of Factor XI: Association of Adsorption Sites with the Heavy Chain of Activated Factor XI

SummaryThese experiments study surface adsorption of native and activated factor XI using purified radiolabelled human factor XI and trypsin activated factor XI. Both forms of factor XI adsorb not only to glass but also to polypropylene, polyethylene and polystyrene. Albumin (10 mg/ml) markedly reduces adsorption to plastics but not to glass. Sodium dodecyl sulfate prevents adsorption to all surfaces tested. Reduction of 125I-activated factor XI in the presence of sodium dodecyl sulfate yields labelled chains of molecular weight of about 46,000 (heavy chain), 37,000 (light chain) and a further breakdown product of about 26,000. Reduction of activated factor XI in glass or plastic in the absence of sodium dodecyl sulfate yields only light chain and breakdown product in solution; heavy chain is removed by adsorption. Therefore, we conclude that the adsorption site (s) in trypsin activated factor XI and presumably also in native factor XI is (are) located in the heavy chain subunit of the molecule.

Factor V activity of platelets: evidence for an activated factor V molecule and for a platelet activator

This study was prompted by the observation that fresh platelet suspensions--prepared by gel filtration or albumin density gradient centrifugation--possessed only minimal factor V activity, whereas frozen-and-thawed platelet suspensions possessed striking factor V activity. Results of experiments with fresh suspensions suggested that unaltered platelets did not bind plasma factor V. The factor V activity of frozen-and-thawed platelet suspensions was markedly diminished after exposure to a factor V antibody, was not activated by thrombin, and was not associated with an increase in factor V antigen over that found in fresh platelet suspensions. Consequently, disruption by freezing and thawing must have resulted in the appearance of small amounts of an activated factor V molecule in platelet suspensions. Disrupted platelets were shown to activate native factor V, but an interaction between a platelet activator and traces of native factor V in fresh suspensions could not be demonstrated to account for the full activity of frozen-and-thawed suspensions. Apparently, therefore, platelets also contained an activated factor V molecule. Adding collagen, but not adenosine 5′-diphosphate to fresh platelet suspensions increased their factor V activity. Release of an activated platelet factor V molecule after exposure to collagen could represent a physiologically significant early step in hemostasis.

Factor V activity of platelets: evidence for an activated factor V molecule and for a platelet activator

This study was prompted by the observation that fresh platelet suspensions--prepared by gel filtration or albumin density gradient centrifugation--possessed only minimal factor V activity, whereas frozen-and-thawed platelet suspensions possessed striking factor V activity. Results of experiments with fresh suspensions suggested that unaltered platelets did not bind plasma factor V. The factor V activity of frozen-and-thawed platelet suspensions was markedly diminished after exposure to a factor V antibody, was not activated by thrombin, and was not associated with an increase in factor V antigen over that found in fresh platelet suspensions. Consequently, disruption by freezing and thawing must have resulted in the appearance of small amounts of an activated factor V molecule in platelet suspensions. Disrupted platelets were shown to activate native factor V, but an interaction between a platelet activator and traces of native factor V in fresh suspensions could not be demonstrated to account for the full activity of frozen-and-thawed suspensions. Apparently, therefore, platelets also contained an activated factor V molecule. Adding collagen, but not adenosine 5′-diphosphate to fresh platelet suspensions increased their factor V activity. Release of an activated platelet factor V molecule after exposure to collagen could represent a physiologically significant early step in hemostasis.

The Activation of Human Factor IX

SummaryThe activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IX a had an apparent molecular weight of about 42–45000 in sodium dodecyl sul-phate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions whereas Ca2+-ions did not influence the activation by kallikrein. A mixture of tissue thromboplastin and factor VII or RusselPs-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

The Activation of Factor VII

Native factor VII (F. VIIn) can be activated by thromboplastin or by the kallikrein-system. This gives rise to two different forms of activated factor VII. We thus discern Factor VIIn, cold activated factor VII (C.P.A-F. VIIa) and thromboplastin activated factor VII (T-F. VIIa).We developed one- and two-stage assays that distinguish between these forms and we tried to establish their interrelationship.T-F. VIIa could be obtained in a form devoid of lipid components and still clearly distinguishable both from factor VIIn and from C.P.A.-F. VIIa. It activates factor X in a thromboplastin-independent process, whereas C.P.A.-F. VIIa is unable to do so.The difference between F. VIIn and C.P.A.-F. VIIa is that the latter is converted into T-F. VIIa much more quickly in a process that shows less species specificity with regard to the type of thromboplastin used.No differences could be seen between T-F. VIIa obtained from V, VIIn directly or via C.P.A.-F. VIIa.