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31.
Kieran F. Scott Timothy J. Mann Shadma Fatima Mila Sajinovic Anshuli Razdan Ryung Rae Kim Adam Cooper Aflah Roohullah Katherine J. Bryant Kasuni K. Gamage David G. Harman Fatemeh Vafaee Garry G. Graham W. Bret Church Pamela J. Russell Qihan Dong Paul de Souza 《Molecules (Basel, Switzerland)》2021,26(23)
Phospholipase A2 (PLA2) enzymes were first recognized as an enzyme activity class in 1961. The secreted (sPLA2) enzymes were the first of the five major classes of human PLA2s to be identified and now number nine catalytically-active structurally homologous proteins. The best-studied of these, group IIA sPLA2, has a clear role in the physiological response to infection and minor injury and acts as an amplifier of pathological inflammation. The enzyme has been a target for anti-inflammatory drug development in multiple disorders where chronic inflammation is a driver of pathology since its cloning in 1989. Despite intensive effort, no clinically approved medicines targeting the enzyme activity have yet been developed. This review catalogues the major discoveries in the human group IIA sPLA2 field, focusing on features of enzyme function that may explain this lack of success and discusses future research that may assist in realizing the potential benefit of targeting this enzyme. Functionally-selective inhibitors together with isoform-selective inhibitors are necessary to limit the apparent toxicity of previous drugs. There is also a need to define the relevance of the catalytic function of hGIIA to human inflammatory pathology relative to its recently-discovered catalysis-independent function. 相似文献
32.
Meredith J Layton Mirette Saad Nicole L Church Richard B Pearson Christina A Mitchell Wayne A Phillips 《BMC biochemistry》2012,13(1):1-9
Background
Hyaluronan (HA) is made at the plasma membrane and secreted into the extracellular medium or matrix by phospolipid-dependent hyaluronan synthase (HAS), which is active as a monomer. Since the mechanism by which HA is translocated across membranes is still unresolved, we assessed the presence of an intraprotein pore within HAS by adding purified Streptococcus equisimilis HAS (SeHAS) to liposomes preloaded with the fluorophore Cascade Blue (CB).Results
CB translocation (efflux) was not observed with mock-purified material from empty vector control E. coli membranes, but was induced by SeHAS, purified from membranes, in a time- and dose-dependent manner. CB efflux was eliminated or greatly reduced when purified SeHAS was first treated under conditions that inhibit enzyme activity: heating, oxidization or cysteine modification with N-ethylmaleimide. Reduced CB efflux also occurred with SeHAS K48E or K48F mutants, in which alteration of K48 within membrane domain 2 causes decreased activity and HA product size. The above results used liposomes containing bovine cardiolipin (BCL). An earlier study testing many synthetic lipids found that the best activating lipid for SeHAS is tetraoleoyl cardiolipin (TO-CL) and that, in contrast, tetramyristoyl cardiolipin (TM-CL) is an inactivating lipid (Weigel et al, J. Biol. Chem. 281, 36542, 2006). Consistent with the effects of these CL species on SeHAS activity, CB efflux was more than 2-fold greater in liposomes made with TO-CL compared to TM-CL.Conclusions
The results indicate the presence of an intraprotein pore in HAS and support a model in which HA is translocated to the exterior by HAS itself. 相似文献33.
Chaya Losada M. Paola Scaparra Richard L. Church Mark S. Daskin 《Annals of Operations Research》2012,201(1):345-365
In this paper we introduce a stochastic interdiction problem for median systems in which the operational state of the system??s disrupted elements in the aftermath of the disruption is uncertain as it is based on the intensity of the disruption. We assume that a disruption disables a facility with a given probability and this probability depends on the intensity of the disruption. The objective of this problem is to identify which disruption scenario entails a maximum overall traveling distance in serving all customers. We show that the initial two stage stochastic formulation can be reformulated into a deterministic counterpart whose size is polynomial in the number of facilities and intensity levels. Then, our ensuing efforts to solve the problem efficiently focus on studying alternative deterministic formulations that allow the solution of realistic size instances of the model. We observe that the most efficient of the deterministic formulations provide great scalability with respect to variations in the input parameters and size of the instances solved. Finally, we analyze the robustness of the optimal solutions due to misestimations in the probability functions that relate disruption intensity levels with the probabilities of facility survivability. 相似文献
34.
35.
A. D. Bauer C. S. Ford A. K. Church J. H. Wilson P. A. Popow J. Davidsohn G. Knigge E. Walter F. Wittka E. J. Better K. Scheringa Per Ekwall H. Janistyn P. Wulff W. Poethke W. Bleyberg H. Lettner J. W. Mc Bain H. E. Martin und E. L. Lederer 《Fresenius' Journal of Analytical Chemistry》1936,104(7-8):306-316
Ohne Zusammenfassung 相似文献
36.
Discrimination decisions arise in many natural language processing tasks. Three classical tasks are discriminating texts by their authors (author identification), discriminating documents by their relevance to some query (information retrieval), and discriminating multi-meaning words by their meanings (sense discrimination). Many other discrimination tasks arise regularly, such as determining whether a particular proper noun represents a person or a place, or whether a given work from some teletype text would be capitalized if both cases had been used.We [9] introduced a method designed for the sense discrimination problems mentioned.We also discuss areas for research based on observed shortcomings of the method. In particular, an example in the author identification task shows the need for a robust version of the method. Also, the method makes an assumption of independence which is demonstrably false, yet there has been no careful study of the results of this assumption. 相似文献
37.
J. Steiger D.A. Church G. Weinberg B.R. Beck J. McDonald D. Schneider 《Hyperfine Interactions》1997,108(1-3):115-119
Electron transfer from H2 to Th79+ was studied in a cryogenic Penning trap by non-destructively observing the sequential development with time of the charge
state of one or a few stored particles. The ratio of the true double capture cross section to the total capture cross section
was found to be 0.21 ± 0.11 at a mean center-of-mass energy near 6 eV.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
38.
Richard L. Church 《Annals of Operations Research》2003,122(1-4):103-120
The p-median problem was first formulated as an integer-linear programming problem by ReVelle and Swain (1970) and further revised by Rosing, ReVelle and Rosing-Vogelaar (1979). These two forms have withstood the test of time, as they have been used by virtually everyone since then. We prove that a property associated with geographical proximity makes it possible to eliminate many of the model variables through a substitution process. This new substitution technique has resulted in the elimination of up to 60% of the variables needed in either of these classic model formulations. 相似文献
39.
Transient behavior of small gas bubbles in a liquid set into violent motion by ultrasonic pressure waves is of interest because of widespread use of microsecond pulses in diagnostic ultrasound. Such pulses contain only a few pressure cycles and the transient pulsations of bubbles set in motion by such pulses would determine the bubble-ultrasound interaction. A computer study has been made to obtain a global representation of the pulsation amplitudes R (t) of small gas bubbles (nuclei) in water during the first few cycles of a cw ultrasonic pressure. One objective was to obtain a better understanding of cavitation phenomena where many nuclei with initial radii Rn from 0.1-20 microns are set in motion at pressures ranging from 0.5-5 bars and at frequencies from 0.5-10 MHz. Results allowed construction of surfaces showing the relative bubble amplitude R/Rn as a function of Rn and of the time t/TA, where TA is the acoustic period. One finding is that, in the range of peak pressures found in diagnostic pulses, transient cavities would be generated during the first pressure cycle from nuclei with initial radii as small as a few microns (micron). Nuclei that grow into transient cavities in the first pressure cycle are here called "prompt" nuclei. At a specified pressure, the size range of radii Rn in which they occur decreases with increasing frequency. At 5 bars, the range of Rn for prompt nuclei is 0.166-11.35 microns at 0.5 MHz and vanishes at 10 MHz. 相似文献
40.
Armstrong TA Bettoni D Bharadwaj V Biino C Borreani G Broemmelsiek D Buzzo A Calabrese R Ceccucci A Cester R Church MD Dalpiaz P Dalpiaz PF Fast JE Ferroni S Ginsburg CM Gollwitzer KE Hahn AA Hasan MA Hsueh SY Lewis RA Luppi E Macr M Majewska A Mandelkern MA Marchetto F Marinelli M Marques JL Marsh W Martini M Masuzawa M Menichetti E Migliori A Mussa R Palestini S Pastrone N Patrignani C Peoples J Pesando L Petrucci F Pia MG Pordes S Rapidis PA Ray RE Reid JD Rinaudo G Rosen JL Santroni A 《Physical review letters》1992,68(10):1468-1471