• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1618-1622
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• 2006

Bacteriophage T7 gp4A' is a ring-shaped hexameric DNA helicase that catalyzes duplex DNA unwinding using dTTP hydrolysis as an energy source. To investigate the effect of single-stranded DNA (ssDNA) on the kinetic pathway of dTTP hydrolysis by the T7 DNA helicase complexed with ssDNA, we have first determined optimal concentration of long circular M13 single-stranded DNA and pre-incubation time in the absence of $Mg^{2+}$ which is necessary for the helicase-ssDNA complex formation. Steady state dTTP hydrolysis in the absence of $Mg^{2+}$ by the helicase-ssDNA complex provided $k_{cat}$ of $8.5\;{\times}\;10^{-3}\;sec^{-1}$. Pre-steady state kinetics of the dTTP hydrolysis by the pre-assembled hexameric helicase was monitored by using the rapid chemical quench-flow technique both in the presence and absence of M13 ssDNA. Pre-steady state dTTP hydrolysis showed distinct burst kinetics in both cases, indicating that product release step is slower than dTTP hydrolysis step. Pre-steady state burst rates were similar both in the presence and absence of ssDNA, while steady state dTTP hydrolysis rate in the presence of ssDNA was much faster than in the absence of ssDNA. These results suggest that single-stranded DNA stimulates dTTP hydrolysis reaction by T7 helicase by enhancing the rate of product release step.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1321-1329
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• 1993

Long time creep strength and life prediction of 1% Cr-Mo-V and 12% Cr rotor steel were performed by using round-bar type specimens under static load at 500-600.deg. C TTP (time temperature parameter), MCM (minimum commitment method) and ISM (initial strain method newly devised) as life prediction methods were investigated, and the results could be summarized as follows. (1) The minimum parameter of SEE (standard error) by TTP was proved as LMP (larson-miller parameter), and the minimum parameter of RMS (root mean squares), by data less than 10$^{3}$hrs was MHP (manson-haferd parameter). (2) The parameters of the minimum and the maximum strength values predicted in $10^{5}$hrs creep life of 1% Cr-Mo-V steel by TTP were LMP and MSP, respectively. In case of 12% Cr steel above $550^{\circ}C$ OSDP (orr-sherby-dorn parameter) was minimum and MSP (manson-succop parameter) was maximum, but below $550^{\circ}C$, the inverse phenomena was observed. On the other hand the creep strengths before $10^{3}hrs$ life by MCM were similar to those by TTP, but the strengths after $10^{3}hrs$ life were 10-25% lower than those by TTP. (3) Creep strengths by ISM were maximum 5% lower than those by TTP. Because $10^{5}hrs$ strengths were similar to those of the lower band by TTP, the ISM was safer than the TTP.

• Journal of The Korean Society of Emergency Medicine
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• v.29 no.5
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• pp.474-484
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• 2018

Objective: The time to positivity (TTP) of blood culture reflects bacterial load and has been reported to be associated with outcome in bloodstream infections. This study was performed to evaluate the relationship between the TTP of blood culture and the mortality rates associated with sepsis and septic shock according to the site of infection. Methods: We performed a retrospective cohort study on patients with sepsis and septic shock. The rates of blood culture positivity and mortality as well as the relationship between the TTP and 28-day mortality rate were compared among patients with different sites of infection, such as the lungs, abdomen, urogenital tract, and other sites. Results: A total of 2,668 patients were included, and the overall mortality rate was 21.6%. The rates of blood culture positivity and mortality were different among the different infection sites. There was no relationship between the TTP and mortality rates of total, lung, and urogenital infections. Patients with abdominal infections showed a negative correlation between the TTP and 28-day mortality rate. In patients with abdominal infections, a TTP<20 hours was independently associated with 28-day mortality compared with patients with negative blood culture (hazard ratio, 1.73; 95% confidence interval, 1.16-2.58). However, there was no difference in mortality rates of patients with a $TTP{\geq}20$ hours and a negative blood culture. Conclusion: The shorter TTP in patients with abdominal infections in sepsis and septic shock was associated with a higher 28-day mortality rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.24-32
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• 2001

Recently, in the case that provides electronic services using Internet, we need the non-repudiation service that supplies a technological evidence about actions between a sender and a receiver that violate the promised protocol. Also, this service offers legal evidences while producing controversy. In this paper, we propose a protocol that improves the efficiency and offers the fairness of non-repudiation service by the extension of ability of TTP (Trusted Third Party). The proposed protocol adds a Time Check function and an Alert Message to extend the ability of TTP. Through the computer simulation, we prove that the proposed protocol has better efficiency than previous protocols.

• Molecules and Cells
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• v.38 no.11
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• pp.991-997
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• 2015

Tristetraprolin (TTP) is an AU-rich elements (AREs)-binding protein, which regulates the decay of ARE-scontaining mRNAs such as proto-oncogenes, anti-apoptotic genes and immune regulatory genes. Despite the low expression of TTP in various human cancers, the mechanism involving suppressed expression of TTP is not fully understood. Here, we demonstrate that Resveratrol (3,5,4'-trihydroxystilbene, Res), a naturally occurring compound, induces glioma cell apoptosis through activation of tristetraprolin (TTP). Res increased TTP expression in U87MG human glioma cells. Res-induced TTP destabilized the urokinase plasminogen activator and urokinase plasminogen activator receptor mRNAs by binding to the ARE regions containing the 3' untranslated regions of their mRNAs. Furthermore, TTP induced by Res suppressed cell growth and induced apoptosis in the human glioma cells. Because of its regulation of TTP expression, these findings suggest that the bioactive dietary compound Res can be used as a novel anti-cancer agent for the treatment of human malignant gliomas.

• Environmental Mutagens and Carcinogens
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• v.10 no.2
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• pp.85-92
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• 1990

The effects of aphidicolin (APC), 2`,3`-dideoxythymidine 5`-triphosphate (ddTTP), and novobiocin (NOV) on the frequencies of chromosome aberrations induced by ethyl methanesulfonate (EMS) or bleomycin (BLM) were examined in synchronized Chinese hamster ovary (CHO)-K$_1$ cells. The cells were synchronized by the thymidine double block method. APC, ddTTP and NOV alone did not affect the frequencies of chromosome aberrations. The cells in late G$_1$ and early S phases were sensitive to the induction of chromosome aberrations by EMS, wherase cells in G$_2$ phase were most sensitive to chromosme aberration by BLM.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.52
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• pp.275-284
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• 1999

The TTP(TimeTabling Problem) for a university which should be made every term is very difficult problem to schedule because each component must satisfy all fixed constraints. This TTP, therefore, is solved by several heuristic methods. In this paper, applying PPEP(Parallel Population Evolution Programs) for the TTP, we try to find the approximated optimal solution by maintaining independence of each subpopulation and by searching the wide feasible solution. In addition, we present the problem to be appeared when used PMX(Partially mapped crossover)operator for the long chromosomes and then propose GBX (Gene_Based crossover)operator which can complement it. Finally, experimental results are presented comparing EP(Evolution Programs) and PPEP, then GBX which has the random genes and the selected genes on a real TTP.

• BMB Reports
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• v.35 no.5
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• pp.524-531
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• 2002

Thrombotic thrombocytopenic purpura (TTP) is characterized by widespread platelet thrombi in arterioles and capillaries. Unusually large or multimeric von Willebrand factor, as well as one or ore platelet-agglutinating factors, have been implicated in the pathogenesis of TTP. But, the actual mechanisms of platelet agglutination have not been satisfactorily explained. Recent studies suggested the 37-kDa platelet-agglutinating protein (PAP) p37 to be partially responsible for the formation of platelet thrombi in patients with TTP. We studied mobility in SDS-PAGE, the sequence of N-terminal amino acid residues, DNA and antigenic characteristics of PAP p37, which might be related to the pathogenesis of TTP. PAP p37 was purified from the plasma of a 31-year-old male Korean patient with acute TTP. The findings are as follows: (1) We compared PAP p37 with thrombin through the use of SDS-PAGE, either with or without $\beta$-mercaptoethanol. PAP p37 did not appear to be cleaved between the A- and B-chains of prethrombin 2. However, thrombin did cleave between those of prethrombin 2, but linked with disulfide bridge. (2) N-terminal 21 amino acid sequence of PAP p37 was T-F-G-S-G-E-A-D-X-G-L-R-P-L-F-E-K-K-S-L-E. It appeared to be identical to that of 285-305 amino acid residues of human prothrombin (prethrombin 2). (3) No prothrombin gene DNA mutation was revealed. (4). The antigenicity of PAP p37 was similar to thrombin, which was a result of the competitive binding against the anti-thrombin antibody. With these results, we conclude that PAP p37 has similar characteristics to prethrombin2.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.270-276
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• 2006

We evaluated the effects of extracts of Tsunokaori tangor peel on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin $E_2\;(PGE_2)$ in RAW 264.7 cells. The ethyl acetate fraction of Tsunokaori tangor peel (EA-TTP) markedly inhibited the production of NO and $PGE_2$ in LPS-stimulated RAW 264.7 cells. Consistent with these findings, the expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins were down-regulated in a dose-dependent manner. Additionally, EA-TTP decreased the expression iNOS mRNA but not COX-2 mRNA. To determine the upstream signaling mechanism for the down-regulation of LPS-induced iNOS expression, we investigated the effect of EA-TTP on the degradation and re-synthesis of $I{\kappa}B{\alpha}$. EA-TTP dose-dependently delayed $I{\kappa}B{\alpha}$ degradation and increased $I{\kappa}B{\alpha}$ re-appearance following degradation, suggesting this as the mechanism by which EA-TTP suppressed iNOS gene expression. The EA-TTP also dose-dependently reduced the expression of the cellular stress-response protein heme oxygenase-1, and inhibited the LPS-induced sustained activation of extracellar signal-regulated kinase (ERK).

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.368-374
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• 2002

In the third generation mobile telecommunication systems such as UMTS, one of the important problems for value-added services is to check the recoverability of costs used by a mobile user. Previous authentication and payment schemes for value-added services by a mobile user across multiple service domains, rely on the concept of the on-line TTP, which serves as the users certification authority. In the third generation systems with many service providers, a wide range of services, and a diverse user population, authentication mechanisms with the on-line TTP provide a far from ideal solution. In this paper we present an efficient public-key protocol for mutual authentication and key exchange designed for value-added services in the third generation mobile telecommunications systems. The proposed ticket based authentication and payment protocol provides an efficient way for VASP to check the recoverability of costs without communication with the on-line TTP Furthermore, the proposed ticket based protocol can provide anonymous service usage for a mobile user.