THE ACTIVATION OF PROTHROMBIN, WITH SPECIAL REFERENCE TO "THROMBOPLASTIC ENZYME" (TRYPTASE)

Abstract A number of high-potency purified prothrombin preparations,61 in 0.2-0.5 per cent solution in borate buffer (pH = 7.7), maintain for days or weeks a stable thrombin-forming ability, whether (a) with buffer alone, (b) with brain thromboplastin suspension, (c) with CaCl2. Nevertheless, they all contain a trace of thrombin and continue to activate "spontaneously" at a very slow rate. Optimal addition of Ca-salt somewhat accelerates this and usually leads to maximal (complete) thrombin formation in 2-11 days at room temperature. Except in a few cases, where ionized Ca++ is demonstrable, thromboplastin, alone, is without effect, but added with calcium, it completes the activation in a matter of minutes or hours depending principally upon the concentration used. Experimental analysis of the activation process stresses the participation of (1) Ca-ions, (2) thromboplastic P-lipid factor (cephalin), (3) plasma and tissue tryptase (proteolytic enzyme). Each of these factors is studied in detail with reference to mode of action, optimal concentration, side-effects, and relation to inhibitors. Inhibition of prothrombin activation may be considered under the following heads: (1) "decalcifying" agents (e.g., oxalates, citrates, etc.), which (a) depress Ca-ionization and thus prevent thrombin formation, and (b), under special circumstances, reverse the process of activation; (2) "antithromboplastic" (? anticephalin) agents, (e.g., heparin, and probably soybean trypsin-inhibitor, to some extent); (3) "antitryptase" agents (e.g., crystalline trypsin-inhibitors from pancreas and soybean), which inhibit the thromboplastic enzyme (accessory factor). Excess Ca++ slows rate of thrombin formation. The evidence suggests that thrombin formation proceeds via an "intermediary" calcium-prothrombin-cephalin (thromboplastic phosphatide) complex or compound. The amounts of (a) thromboplastic P-lipid (cephalin or "thromboplastin") and (b) Ca++ determine both the rate of activation and the final thrombin yield. However, the ultimate ("ripe") thrombin owes none of its activity to the presence of any calcium or phospholipid. The three types of activator (Ca, thromboplastin, and thromboplastic enzyme) occur as "trace impurities" in prothrombin preparations, but Seegers’ most purified materials are tryptase-free. Tryptase (and trypsin) are "thromboplastic" only in the presence of adequate calcium and phospholipid factors, which may, however, be "mobilized" from protein combination, including prothrombin. In this way the two basic activators are, in a sense, "catalyzed" in their prothrombin-activating reactions. The significance of proteolytic actions (fibrinolysis, fibrinogenolysis, prothrombinolysis, and sometimes thrombinolysis) by natural tryptase of plasma and tissue origin is investigated and discussed in relation to the broader aspects of the blood-coagulation problem.

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Use of mechanical activation in the processing of gold-bearing ores and anthropogenic materials

E3S Web of Conferences ◽

10.1051/e3sconf/202019202017 ◽

2020 ◽

Vol 192 ◽

pp. 02017

Author(s):

Natalia Litvinova ◽

Aleksandra Kopylova ◽

Valentina Stepanova ◽

Hitachi Tatsumi

Keyword(s):

Mechanical Activation ◽

Alkali Metals ◽

Chemical Elements ◽

Experimental Studies ◽

Accessory Mineral ◽

Complexing Agent ◽

Activation Process ◽

Eastern Region ◽

Trace Impurities ◽

Gold Bearing

The results of experimental studies on the use of mechanical activation in the processing of ores and anthropogenic materials of the Far Eastern region are presented. The effectiveness of the use of electrophotoactivated solutions and complex reagents at the stage of mineral preparation has been established. Technological solutions have been proposed to reduce the loss of finely dispersed and chemically bonded gold during the processing of gold-bearing materials based on a directed change in the properties of the surface of minerals. The effectiveness of the use of the mechanochemical activation process for various aspects of the technological chain has been experimentally confirmed – a decrease in the sorption properties of materials, development of microcracks in oxidized ores for the penetration of leaching solutions into mineral aggregates, oxidation of the surface of primary ores, and removal of films from the mineral surface. Indicators of technological refractoriness of the studied ores and anthropogenic materials were revealed – a high proportion of chemically bound gold with atoms of basic and accessory mineral-forming elements, the presence of grains of the valuable component covered with oxide films, enclosed in carbonates, quartz and waste rock. The refractoriness of ores is confirmed by a high sorption capacity (the predominance of carbonaceous and clay matter), the presence of trace impurities in gold (Sb, As, Cu, Fe, Hg), which increase the consumption of cyanide during leaching. The material composition is dominated by a significant amount of chemical elements – cyanosides, actively interacting with the main complexing agent of leaching solutions – cyanide of alkali metals.

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A RAPID METHOD FOR THE DETERMINATION OF PROTEOLYTIC ACTIVITIES OF ENZYME PREPARATIONS

The Journal of General Physiology ◽

10.1085/jgp.32.1.17 ◽

1948 ◽

Vol 32 (1) ◽

pp. 17-24 ◽

Cited By ~ 7

Author(s):

Bacon F. Chow ◽

Mary-Ann Peticolas

Keyword(s):

Enzyme Activity ◽

Trichloroacetic Acid ◽

Enzyme Concentration ◽

Cent Solution ◽

Enzyme Preparations ◽

Proteolytic Activities ◽

Activity Of Enzymes ◽

Different Sources ◽

Rate Of Activation

A method has been described for the determination of proteolytic activities of enzyme preparations using casein as substrate. The rate of digestion is proportional to the enzyme concentration used. This relationship is utilized as a measure of the enzyme activity. One unit of activity is defined as the amount which is required to digest casein in 15 minutes at 37.5°C. so that 50 per cent of the protein in 1 ml. of 0.25 per cent solution is not precipitable by trichloroacetic acid. This method has been used to determine the activity of enzymes from different sources and also used to follow the rate of activation of enzymes.

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The Formation of the Haemostatic Plug – A Special Case of Platelet Aggregation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649474 ◽

1993 ◽

Vol 70 (02) ◽

pp. 234-237 ◽

Cited By ~ 26

Author(s):

Ernst F Lüscher ◽

Susanne Weber

Keyword(s):

Platelet Aggregation ◽

Platelet Activation ◽

Activation Process ◽

Fast Process ◽

Vital Importance ◽

Artificial Surfaces ◽

Special Case ◽

Thrombin Formation

SummaryThe formation of the haemostatic plug is an extremely fast process. This excludes, at least in its first phase, the involvement of soluble activating agents released from or produced by the platelets. An experiment with ADP-activated, formaldehyde-fixed platelets shows that platelets with activated fibrinogen receptors will bind inactive platelets in the presence of fibrinogen and Ca2+-ions. A survey of the literature shows that platelet activation is accompanied by the clustering of the fibrinogen receptors. The surface of an activated platelet, which makes part of the growing haemostatic plug therefore is covered with patches of tightly packed fibrinogen. This allows the multisite combination with the statistically distributed low affinity receptors of the newly arriving platelets. Tightly packed fibrinogen, as present on clusters of the activated GP IIb/IIIa receptors as well as when absorbed to artificial surfaces acts as an activator of platelets. Thus, the propagation of the activation process is possible without a requirement for other, external activators. Such agents, which are released from platelets and, finally, thrombin formation, are nonetheless of vital importance, not for the formation but for the consolidation of the haemostatic plug.

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Assay for Prekallikrein Levels and Prekallikrein Activation in Human Plasma Using Dextran Sulphate as a Soluble Activator

10.1055/s-0039-1680669 ◽

1977 ◽

Author(s):

C. Kluft

Keyword(s):

Entire Range ◽

Activation Process ◽

Factor Xii ◽

Dextran Sulphate ◽

Healthy Individuals ◽

High Dilution ◽

Plasma Activation ◽

Kallikrein Activity ◽

Rate Of Activation ◽

Apparently Healthy

Incubation of human citrated plasma with dextran sulphate at 0°C was found to generate kallikrein activity as determined with the chromogenic synthetic tripeptide α-N-Bz-Pro-Phe-Arg-p. nitroanilide (0.16 mM). The possible use of the synthetic soluble dextran sulphate (MW 500,000) instead of the commonly used insoluble kaolin for activating the plasma kallikrein system was explored. The rate of activation of prekallikrein to kallikrein was dependent on: a) the concentration of dextran sulphate until a plateau was reached at 12.5 μg/ml; and b) the concentration of factor XII in the entire range up to 100%, as varied by mixing deficient and normal plasma. Activation was only slightly influenced by increased levels of C1-inactivator. In comparing dextran sulphate with kaolin, it was noticed that activation by means of dextran sulphate was slower (optimum at 7 and 2 min, respectively) and could be stopped by dilution. With kaolin (or glass), the activation continued even at high dilution (1:162) in the cuvet, preventing a proper study of the activation process. Dextran sulphate also did not interfere with the spectrophoto-metric assay, in contrast to the light-scattering properties of the insoluble kaolin. Optimum conversion of prekallikrein to kallikrein is reached in normal pooled plasma in 7 min at 0°C with 25 μg/ml dextran sulphate. The same is true for other plasma samples, if not liable to unwanted preactivation or incomplete activation, as revealed by control experiments. In 15 apparently healthy individuals, a mean activity of 476 ± 58 (SD) mU/ml was found. It is concluded that dextran sulphate can be used advantageously in the assay of prekallikrein activation and prekallikrein levels.

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Ultrastructural Aspects of Golgi Complex Function in Parathyroid Cells of Winter Frogs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100073842 ◽

1973 ◽

Vol 31 ◽

pp. 680-681

Author(s):

William J. Dougherty

Keyword(s):

Golgi Complex ◽

Secretory Granules ◽

Complex Function ◽

Secretory Activity ◽

Secretory Proteins ◽

Perivascular Spaces ◽

Pituitary Cells ◽

Electron Microscopic ◽

Ca Ions ◽

Regulation Of Secretion

The regulation of secretion in exocrine and endocrine cells has long been of interest. Electron microscopic and other studies have demonstrated that secretory proteins synthesized on ribosomes are transported by the rough ER to the Golgi complex where they are concentrated into secretory granules. During active secretion, secretory granules fuse with the cell membrane, liberating and discharging their contents into the perivascular spaces. When secretory activity is suppressed in anterior pituitary cells, undischarged secretory granules may be degraded by lysosomes. In the parathyroid gland, evidence indicates that the level of blood Ca ions regulates both the production and release of parathormone. Thus, when serum Ca is low, synthesis and release of parathormone are both stimulated; when serum Ca is elevated, these processes are inhibited.

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SEM and Auger microanalysis studies of Cu-Be dynode surfaces at each activation condition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109768 ◽

1978 ◽

Vol 36 (1) ◽

pp. 524-525

Author(s):

T. Koshikawa ◽

Y. Fujii ◽

E. Sugata ◽

F. Kanematsu

Keyword(s):

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Life Time ◽

Activation Process ◽

Beam Diameter ◽

Activation Temperature ◽

Electron Multiplier ◽

Activation Condition ◽

Activation Conditions

The Cu-Be alloys are widely used as the electron multiplier dynodes after the adequate activation process. But the structures and compositions of the elements on the activated surfaces were not studied clearly. The Cu-Be alloys are heated in the oxygen atmosphere in the usual activation techniques. The activation conditions, e.g. temperature and O2 pressure, affect strongly the secondary electron yield and life time of dynodes.In the present paper, the activated Cu-Be dynode surfaces at each condition are investigated with Scanning Auger Microanalyzer (SAM) (primary beam diameter: 3μmϕ) and SEM. The commercial Cu-Be(2%) alloys were polished with Cr2O3 powder, rinsed in the distilled water and set in the vacuum furnance.Two typical activation condition, i.e. activation temperature 730°C and 810°C in 5x10-3 Torr O2 pressure were chosen since the formation mechanism of the BeO film on the Cu-Be alloys was guessed to be very different at each temperature from the results of the secondary electron emission measurements.

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Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086180 ◽

1991 ◽

Vol 49 ◽

pp. 376-377 ◽

Cited By ~ 1

Author(s):

N.J. Tao ◽

J.A. DeRose ◽

P.I. Oden ◽

S.M. Lindsay

Keyword(s):

Surface Charge ◽

Environmental Effects ◽

Scanning Probe Microscopy ◽

Statistical Significance ◽

Electrochemical Methods ◽

Surface Structures ◽

Scanning Probe ◽

Potential Control ◽

Afm Imaging ◽

Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

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Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130298 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1132-1133

Author(s):

Mark Denker ◽

Jennifer Wall ◽

Mark Ray ◽

Richard Linton

Keyword(s):

Secondary Ion Mass Spectrometry ◽

Incidence Angle ◽

Ion Beam ◽

Depth Profiling ◽

Depth Resolution ◽

Ion Beams ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Trace Impurities ◽

Energy Dose

Reactive ion beams such as O2+ and Cs+ are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.

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Suicide-Related Crimes in Contemporary European Criminal Laws

Crisis ◽

10.1027/0227-5910.18.1.35 ◽

1997 ◽

Vol 18 (1) ◽

pp. 35-47 ◽

Cited By ~ 4

Author(s):

Ilkka Henrik Mäkinen

Keyword(s):

Suicide Prevention ◽

Suicide Mortality ◽

Legal Systems ◽

Cultural Attitudes ◽

Public Opinions ◽

Suicide Rates ◽

Narrow Scope ◽

National Affair ◽

Attitudes Towards Suicide ◽

Special Circumstances

This article describes suicide-related penal legislation in contemporary Europe, and analyzes and relates the results to cultural attitudes towards suicide and to national suicide rates. Data were obtained from 42 legal entities. Of these, 34 have penal regulations which - according to definition - chiefly and directly deal with suicide. There are three main types of act: aiding suicide, abetting suicide, and driving to suicide. The laws vary considerably with regard to which acts are sanctioned, how severely they are punished, and whether any special circumstances such as the motive, the result, or the object can make the crime more serious. Various ideologies have inspired legislation: religions, the euthanasia movement, and suicide prevention have all left their mark. There are some cases in which neighboring legal systems have clearly influenced laws on the topic. However, the process seems mostly to have been a national affair, resulting in surprisingly large discrepancies between European legal systems. The laws seem to reflect public opinions: countries which punish the crimes harder have significantly less permissive cultural attitudes towards suicide. Likewise, suicide rates were significantly higher in countries with a narrow scope of criminalization and milder punishments for suicide-related crimes. The cultural and normative elements of society are connected with its suicide mortality.

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