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  • 1
    Electronic Resource
    Electronic Resource
    Different evolutionary histories of kringle and protease domains in serine proteases: A typical example of domain evolution (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 331-336 
    Details
    ISSN: 1432-1432
    Keywords: Kringle domain ; Protease domain ; Serine protease ; Domain evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With the aim of elucidating the evolutionary processes of the kringle and protease domains in serine proteases which are involved with the system of blood coagulation and fibrinolysis, we constructed phylogenetic trees for the kringle and protease domains, separately, by use of amino acid sequence data. The phylogenetic trees constructed clearly showed that the topologies were different between the kringle and protease domains. Because both domains are coded by single peptides of serine proteases, this strongly suggests that the kringle and protease domains must have undergone different evolutionary processes. Thus, these observations imply that serine proteases evolve in a way such that each domain is a unit of evolution, exemplifying a typical mode of domain evolution. A possible relationship between the domain evolution and the exon shuffling theory is also discussed from the viewpoint of gene evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163238
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  • 2
    Electronic Resource
    Electronic Resource
    Evolutionary origin of a Kunitz-type trypsin inhibitor domain inserted in the amyloid β precursor protein of Alzheimer's disease (1992)
    Springer
    Journal of molecular evolution 34 (1992), S. 536-543 
    Details
    ISSN: 1432-1432
    Keywords: Serine protease inhibitor ; Kunitz type ; Evolutionary origin ; Alzheimer's disease ; Insertion sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Kunitz-type protease inhibitor is one of the serine protease inhibitors. It is found in blood, saliva, and all tissues in mammals. Recently, a Kunitz-type sequence was found in the protein sequence of the amyloid β precursor protein (βAPP). It is known that βAPP accumulates in the neuritic plaques and cerebrovascular deposits of patients with Alzheimer's disease. Collagen type VI in chicken also has an insertion of a Kunitz-type sequence. To elucidate the evolutionary origin of these insertion sequences, we constructed a phylogenetic tree by use of all the available sequences of Kunitz-type inhibitors. The tree shows that the ancestral gene of the Kunitz-type inhibitor appeared about 500 million years ago. Thereafter, this gene duplicated itself many times, and some of the duplicates were inserted into other protein-coding genes. During this process, the Kunitz-type sequence in the present βAPP gene diverged from its ancestral gene about 270 million years ago and was inserted into the gene soon after duplication. Although the function of the insertion sequences is unknown, our molecular evolutionary analysis shows that these insertion sequences in βAPP have an evolutionarily close relationship with the inter-α-trypsin inhibitor or trypstatin, which inhibits the activity of tryptase, a novel membrane-bound serine protease in human T4+ lymphocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160466
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  • 3
    Electronic Resource
    Electronic Resource
    Branch Length Heterogeneity Leads to Nonindependent Branch Length Estimates and Can Decrease the Efficiency of Methods of Phylogenetic Inference (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 392-405 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Branch length heterogeneity — Branch length estimation — Phylogenetic inference — Maximum likelihood — Minimum evolution — Taxon sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Branch length estimates play a central role in maximum-likelihood (ML) and minimum-evolution (ME) methods of phylogenetic inference. For various reasons, branch length estimates are not statistically independent under ML or ME. We studied the response of correlations among branch length estimates to the degree of among-branch length heterogeneity (BLH) in the model (true) tree. The frequency and magnitude of (especially negative) correlations among branch length estimates were both shown to increase as BLH increases under simulation and analytically. For ML, we used the correct model (Jukes–Cantor). For ME, we employed ordinary least-squares (OLS) branch lengths estimated under both simple p-distances and Jukes–Cantor distances, analyzed with and without an among-site rate heterogeneity parameter. The efficiency of ME and ML was also shown to decrease in response to increased BLH. We note that the shape of the true tree will in part determine BLH and represents a critical factor in the probability of recovering the correct topology. An important finding suggests that researchers cannot expect that different branches that were in fact the same length will have the same probability of being accurately reconstructed when BLH exists in the overall tree. We conclude that methods designed to minimize the interdependencies of branch length estimates (BLEs) may (1) reduce both the variance and the covariance associated with the estimates and (2) increase the efficiency of model-based optimality criteria. We speculate on possible ways to reduce the nonindependence of BLEs under OLS and ML.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006563
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  • 4
    Electronic Resource
    Electronic Resource
    Role of Structural Complexities of Septal Tissue in Maintaining Ventricular Fibrillation in Isolated, Perfused Canine Ventricle (2001)
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 12 (2001), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Tissue Structure and VF. Introduction: It is unclear how the patterns of wavelet propagation during ventricular fibrillation (VF) vary between structurally different tissues. We hypothesized that the structural complexities of septal tissue influence the maintenance of reentrant wavelets in the ventricle. Methods and Results: Endocardial activation patterns during VF were analyzed in the isolated, perfused canine right ventricular (RV) free wall (n = 9), interventricular septum (n = 5), and left ventricular (LV) free wall (n = 6) using a computerized mapping system (2-mm resolution) with 120-msec consecutive windows. Each tissue sample was cut progressively to reduce the tissue mass until the VF was terminated. More wavelets were seen in the septa than in the RV and LV free walls at baseline (P = 0.004), and VF in the septa displayed a shorter cycle length than in the RV and LV free walls (P = 0.017). As the tissue mass decreased, VF became successively more organized in all regions: the number of wavelets decreased and the cycle length of VF lengthened. Single and “figure-of-eight” stationary, reentrant wavelets often were mapped after tissue mass reduction in the RV free walls and rarely in the LV free walls, but they were not observed in the septa. Less critical mass was required to maintain VF in the septa than in the RV and LV free walls (P = 0.0006). Gross anatomic and histologic examinations indicated that the tissue structure of the septa is more complex than that of the RV and LV free walls. Conclusion: VF activation patterns with progressive reduction of tissue mass differ for the septum and the ventricular free walls. The structural complexities of the septal tissue influence the maintenance of fibrillation in the ventricle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2001.00066.x
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  • 5
    Electronic Resource
    Electronic Resource
    Identification and purification of Namalwa nuclear RNP antigen 52/5.3 (1983)
    Springer
    Journal of cancer research and clinical oncology 105 (1983), S. 67-75 
    Details
    ISSN: 1432-1335
    Keywords: Nucleolar antigens ; Nuclear RNP ; Nuclear proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using affinity purified rabbit antibodies to HeLa nucleoli and the Western blotting techniques, an antigen with an approximate molecular weight of 52,000 and pI of 5.3 was found in Namalwa cells (a Burkitt lymphoma), but not in normal liver cells. This antigen was purified from Namalwa RNP by column chromatography on Sephacryl S-200, hydroxylapatite and one-dimensional SDS gel electrophoresis. A liver protein with the same molecular weight and pI value was purified from RNP fraction by one-dimensional SDS gel eletrophoresis. Both proteins had similar amino-acid compositions. The tryptic map of 125I-labeled protein 52/5.3 contained approximately nine major spots; spot 9 was present in the Namalwa protein but not in the liver protein. The similarity of the structures of these proteins and their differences in antigenicity are noteworthy and require further structural and functional analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391834
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  • 6
    Electronic Resource
    Electronic Resource
    On the polymerization of formaldehyde in liquid state. I. Gamma ray-initiated polymerization of the monomer in solution (1965)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 83 (1965), S. 23-34 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die durch Gammastrahlen initiierte Polymerisation von Formaldehyd in Toluol und Äthylbromid bei -50 bis -80°C wird untersucht und die Kinetik ausführlicher als in der ersten Arbeit2 diskutiert.Die Bruttoreaktion ist von 3. Ordnung bezüglich des Monomeren und von 1. Ordnung bezüglich der Strahlungsdosis; das Molekulargewicht dagegen ist weitgehend unabhängig von der Strahlungsdosis und von der Monomerkonzentration. Es wird angenommen, daß die Polymerisation nach einem ionischen Mechanismus abläuft, wobei das Molekulargewicht im wesentlichen durch eine Kettenübertragung mit dem Monomeren bestimmt wird.
    Notes: This paper presents a more detailed discussion on the kinetics of formaldehyde polymerization under gamma-irradiation than the previous paper2. Polymerization took place in toluene and ethyl bromide and within the range of -50°∼-80°C.The overall reaction is approximately third-order with respect to the monomer. The average molecular weight of the polyoxymethylene obtained is little dependent on the initial concentration of the monomer and on dose rate. The reaction is approximately first order with respect to dose rate. It is believed from the facts obtained here that the polymerization, in which the transfer process of growing chain to monomer is mainly responsible for governing the molecular weight, should proceed predominantly by an ionic mechanism.A study of the influence of various additives upon the polymerization shows the following results. These additives are classified in four groups with respect to their qualities, the first group having influence only upon the polymerization rate (e.g., diphenylpicrylhydrazyl), the second only upon the molecular weight (water), the third upon both of these factors (methyl formate, methyl acetate, ethyl acetoacetate, polystyrene powder, and tetrahydrofuran), and the last having no influence upon both of these factors (oxygen, carbon monoxide, nitrobenzene, and naphthalene).The apparent activation energy is estimated to be 4.15 kcal/mole from rate of polymerization, -3.50 kcal./mole from average degree of polymerization.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1965.020830103
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  • 7
    Electronic Resource
    Electronic Resource
    On the polymerization of formaldehyde in the liquid state. II. Gamma ray-initiated polymerization in a dispersed system (1965)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 89 (1965), S. 245-256 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der bei -80°C durch 60Co-γ-Strahlung ausgelösten Polymerisation von Formaldehyd wurde untersucht. Dispersionsmittel waren Methylcyclohexan und n-Heptan: Sorbitansesquioleat diente als nichtionisches Detergens.Die Anfangsgeschwindigkeit der Polymerisation wird von Größe oder Zahl der Monomertröpfehen nicht beeinflußt; sie ist auch nur wenig vom Dispersionsmittel oder von der Detergenskonzentration abhängig. Der Intensitätsexponent liegt nahe bei 0,9. Das Molekulargewicht ist weitgehend unabhängig von der Dosisleistung. Diese Befunde führen zu dem Schluß. daß nahezu alle aktiven Zentren in den Monomertröpfchen gebildet werden und daß eine monomolekulare Abbruchreaktion vorliegt.Die Anfangsgeschwindigkeit der Polymerisation und der mittlere Polymerisationsgrad sind innerhalb eines gewissen Bereiches kaum von der Monomermenge abhängig; bei mehr als 60 % Formaldehyd in der Emulsion steigt die Polymerisationsgeschwindigkeit jedoch rasch an und erreicht schließlich den Wert für die Substanzpolymerisation. Der mittlere Polymerisationsgrad nimmt mit zunehmender Strahlendosis ein wenig ab.Mikroskopische Beobachtungen zeigen, daß bis zu etwa 30 % Umsatz die Zahl der Polymerkügelchen ansteigt, die weitere Reaktion führt dann zu einer Vergrößerung der Polymerpartikelchen.
    Notes: This paper presents a discussion on the kinetics of formaldehyde polymerization in a dispersed system under 60Co-γ-irradiation. Polymerization took place at -80°C. in methylcyclohexane and n-heptane, using sorbitan sesquioleate as nonionic detergent.The initial rate of polymerization is little dependent on the concentration of detergent within the concentration range investigated, on the type of dispersion medium. Namely, the process is unaffected by the size and number of the monomer droplets. The intensity exponent is close to 0.9 and the molecular weight of the polymer is little affected by dose rate. These facts lead to the reasonable conclusion that almost all the active centers are generated in the monomer globules and that in the polymerization unimolecular termination is operative.Both the initial rate of polymerization and average degree of polymerization are little dependent on the amount of monomer within a certain range. However, the polymerization rate increases rapidly with increasing amount of monomer beyond about 60 wt.-% and approaches that of bulk polymerization. The average degree of polymerization tends to diminish with increasing dose.It was microscopically observed that the increase of conversion was accompanied mainly by the increase of the number of polymer globules below about 30 wt.-% conversion and by the growth to the larger size of polymer globules formed beyond about 30 wt.-% conversion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1965.020890118
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