To see the other types of publications on this topic, follow the link: PcTF.
Journal articles on the topic 'PcTF'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'PcTF.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Bhunia, Asamanjoy, Dolores Esquivel, Subarna Dey, Ricardo Fernández-Terán, Yasutomo Goto, Shinji Inagaki, Pascal Van Der Voort, and Christoph Janiak. "A photoluminescent covalent triazine framework: CO2 adsorption, light-driven hydrogen evolution and sensing of nitroaromatics." Journal of Materials Chemistry A 4, no. 35 (2016): 13450–57. http://dx.doi.org/10.1039/c6ta04623a.
Full text
2
Perera, Clifford, Udayangani Ramadasa, Chandrika Wijeratne, Panduka Karunanayake, Thashi Chang, Gamini Pathirana, Ravini Karunathilake, Suraj Perera, Kalyani Guruge, and Sankha Randenikumara. "Establishment of Palliative and End-of-Life Care Services in Sri Lanka." Prehospital and Disaster Medicine 34, s1 (May 2019): s127—s128. http://dx.doi.org/10.1017/s1049023x19002760.
Full textAbstract:
Introduction:Sri Lanka has a rapidly aging population with an exponential rise in chronic morbidity. There had been no parallel development of palliative and end-of-life care-specific approach in health care.Aim:To implement sustainable palliative and end-of-life care services in Sri Lanka through the existing systems and resources by advocacy, collaboration, and professional commitment.Methods:Sri Lanka Medical Association established a volunteer task force for palliative and end-of-life care (PCTF) in October 2016, which comprised of multi-disciplinary health care professionals, legal fraternity, and civil society. PCTF identified the need for sensitizing the general public on the importance of palliative care, for standard guidelines and formal training for practicing health care professionals engaged in hospital and community-based palliative care. These needs are addressed through activities of PCTF in collaboration with the Ministry of Health.Results:Representing the National Steering Committee of Palliative Care, the members of the PCTF were instrumental in developing the National Strategic Framework to fill the major gap of affordable quality palliative care in the country. PCTF also published the “Palliative Care Manual for Management of Non-Cancer Patients” as a preliminary guide for health care professionals. The draft document on the End-of-Life Care Guidelines has been formulated and is currently being reviewed by the relevant medical and legal stakeholders. PCTF has organized CME lectures on palliative care all over the country for health care professionals, and also conducted lectures, exhibitions, and mass media programs to sensitize the public on palliative care.Discussion:Within a brief period, PCTF has played a key role to recognize palliative care by contributing to policy making, training, and public sensitization in palliative and end-of-life care in Sri Lanka.
3
Frank, Joachim. "New challenges to image processing posed by cryo-Electron microscopy of single particles." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 422–23. http://dx.doi.org/10.1017/s0424820100086416.
Full textAbstract:
Compared with images of negatively stained single particle specimens, those obtained by cryo-electron microscopy have the following new features: (a) higher “signal” variability due to a higher variability of particle orientation; (b) reduced signal/noise ratio (S/N); (c) virtual absence of low-spatial-frequency information related to elastic scattering, due to the properties of the phase contrast transfer function (PCTF); and (d) reduced resolution due to the efforts of the microscopist to boost the PCTF at low spatial frequencies, in his attempt to obtain recognizable particle images.
4
Gu, Chunyang, Deyu Liu, Wei Huang, Jie Liu, and Renqiang Yang. "Synthesis of covalent triazine-based frameworks with high CO2 adsorption and selectivity." Polymer Chemistry 6, no. 42 (2015): 7410–17. http://dx.doi.org/10.1039/c5py01090j.
Full text
5
de Jong, A. F., W. M. J. Coene, and A. J. Koster. "Measurement of PCTF parameters with high accuracy." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (August 1992): 136–37. http://dx.doi.org/10.1017/s0424820100121089.
Full textAbstract:
Measurement of electron-optical parameters in TEM is important for two reasons: a) for automatic correction of focus, astigmatism and beam-tilt misalignment (autotuning) and b) for the accurate determination of the phase-contrast transfer function (PCTF) which is needed for a correct interpretation of high-resolution electron microscopy (HREM) images. This paper addresses specifically methods adapted to reach the second goal, stressing accuracy rather than speed and robusteness.
6
Hosokawa, F., T. Osuna, M. Suzuki, and T. Oikawa. "Determination of Intensity Distribution of Effective Source by Means of PIXsysTEM." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 72–73. http://dx.doi.org/10.1017/s0424820100179117.
Full textAbstract:
The resolution of the transmission electron microscope is discussed considering its phase contrast transfer function (PCTF). Usually, as the envelope function for PCTF, the defocus due to the chromatic aberration (ED) and the reduction of the interference (EJ) due to the incidence angle of the electron beam upon the specimen are considered. It was shown by Frank that the latter is given by the Fourier transformation of the effective source. In the present study, the author shows that EJ can be calculated from the intensity distribution of a filament image formed near the back focal plane of the objective lens. This means that we can virtually get the profile of the effective source without focusing the exact back focal plane on the fluorescent screen, in the diffraction mood. Using the PIXsysTEM, the author also investigated the profile function of the effective electron source and calculated EJ values under various illumination conditions.Assume that the specimen is thin enough to be approximated as a weak phase object. In Fig. 1, consider A and B as filament images formed near the back focal plane of the objective lens by transmitted wave and scattered wave, respectively. They act as emitting sources for the image plane.
7
Probst, W., E. Zellmann, G. Benner, and E. Weimer. "Cryo imaging using an energy-filtering TEM (EFTEM): Optimum use of phase-contrast transfer function (PCTF)." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 506–7. http://dx.doi.org/10.1017/s0424820100170268.
Full textAbstract:
Lack of contrast is one of the numerous problems arising from imaging of vitrified biological macromolecules in a TEM. This is due to the similar density of biological material and of vitreous ice and to the high background of inelastic scattering in the ice which is about four times that of carbon.Consequently in a CTEM images have to be recorded 1-3 μm underfocus to maximise phase contrast which in the same sense decreases the reliability of density information.Elastic filtering using an (EFTEM) allows closer to focus imaging still achieving considerable contrast. For 3D reconstruction of molecular densities the largest source of error is likely to arise from contributions of the PCTF. Thus, such images have to be corrected for the PCTF, which is much morereliably done for elastically filtered images close to focus.Thin vitreous ice films containing the virus particles were prepared on holey carbon grids and examined with cryo EM procedures. Images of frozen-hydrated cucumber mosaic virus (CCMV) particles ( Ø of roughly 25 nm) were recorded in Elastic Brightfield mode using the Zeiss EM 912 OMEGA with integrated imaging spectrometer and Koehler Illumination. Magnification was 50.000x, HT 120 kV, energy width 7 eV, total dose 800 electrons /nm2.
8
Kim, Hye-Eun, Maiko Shitashiro, Akio Kuroda, Noboru Takiguchi, Hisao Ohtake, and Junichi Kato. "Identification and Characterization of the Chemotactic Transducer in Pseudomonas aeruginosa PAO1 for Positive Chemotaxis to Trichloroethylene." Journal of Bacteriology 188, no. 18 (September 15, 2006): 6700–6702. http://dx.doi.org/10.1128/jb.00584-06.
Full textAbstract:
ABSTRACT Pseudomonas aeruginosa PAO1 is repelled by trichloroethylene (TCE), and the methyl-accepting chemotaxis proteins PctA, PctB, and PctC serve as the major chemoreceptors for negative chemotaxis to TCE. In this study, we found that the pctABC triple mutant of P. aeruginosa PAO1 was attracted by TCE. Chemotaxis assays of a set of mutants containing deletions in 26 potential mcp genes revealed that mcpA (PA0180) is the chemoreceptor for positive chemotaxis to TCE. McpA also detects tetrachloroethylene and dichloroethylene isomers as attractants.
9
Hosokawa, F., T. Tomita, T. Honda, and M. Kersker. "Ultra-High Resolution with The Jem-2010F Field-Emission Tem." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 464–65. http://dx.doi.org/10.1017/s0424820100164787.
Full textAbstract:
Historically, high probe current in small probes has been the principal virtue of the field emission TEM. Analytical performance is greatly enhanced[1] and fine probe mapping an important analytical tool for trace element segregation and very fine scale high resolution chemical imaging. Less appreciated is the enhanced high resolution capability due to the small energy spread of the electron source and higher coherency due to reduced primary and virtual source size. The envelope function of the phase contrast transfer function (PCTF) is drastically improved reducing image blurring due to both chromatic aberration and specimen illumination angle. This is especially true for the high spatial frequencies beyond the first zero. Intensities sufficient for image formation can be obtained from these higher frequency regions. Since the PCTF does not change its form, photographing images at the Scherzer condition will yield higher resolution with higher coherency, however, the transfer of the specimen potential corresponding to contrast enhanced regions is in the oscillations form beyond the first zero. Changes in the defocus will lead to changes in transferred frequencies beyond the first zero and possible extinctions of otherwise transferred information since the oscillations will pass through zero contrast. Interpretation of images under these conditions will, therefore, require accurate measurement of the optical parameters of the microscope and especially accurate measurements of the defocus conditions. It is also important to calculate images under these conditions for comparison with measured images which give the insurance of defocus conditions supposed to be presented.
10
Struck, Joachim, Martina Strebelow, Sonja Tietz, Christine Alonso, Nils G. Morgenthaler, Johannes G. van der Hoeven, Peter Pickkers, and Andreas Bergmann. "Method for the Selective Measurement of Amino-Terminal Variants of Procalcitonin." Clinical Chemistry 55, no. 9 (September 1, 2009): 1672–79. http://dx.doi.org/10.1373/clinchem.2008.123018.
Full textAbstract:
Abstract Background: Procalcitonin (PCT) is an established marker for diagnosing and monitoring bacterial infections. Full-length PCT [116 amino acids that make up procalcitonin (PCT1–116)] can be truncated, leading to des-Ala-Pro-PCT (des-Alanin-Prolin-Procalcitonin; PCT3–116). Current immunoassays for PCT (“total PCT”) use antibodies directed against internal epitopes and are unable to distinguish amino-terminal PCT variants. Here we describe the development of monoclonal antibodies recognizing the amino-termini of PCT1–116 and PCT3–116 and their use in the selective measurement of these PCT species. Methods: With newly developed monoclonal antibodies against the amino-termini of PCT1–116 and PCT3–116, and an antibody against the katacalcin moiety of PCT, we developed and characterized immunoluminometric assays for the 2 PCT peptides. We comparatively assessed the kinetics of PCT variants in a human endotoxemia model. Results: Monoclonal antibodies against the amino-termini of PCT1–116 and PCT3–116 showed <1% cross-reactivity with other PCT-related peptides. The sandwich assays for PCT1–116 and PCT3–116 had functional assay sensitivities of 5 and 1.2 pmol/L, respectively, and exhibited recoveries within 20% of expected values. Plasma PCT1–116 was stable for 6 h at 22 °C and 24 h at 4 °C, and PCT3–116 was stable for at least 24 h at both temperatures. During experimental endotoxemia in healthy people, both PCT1–116 and PCT3–116 increased early in parallel with total PCT, but further increases in PCT1–116 were significantly slower than for PCT3–116 (P = 0.0049) and total PCT (P = 0.0024). Conclusions: The new assays selectively measure PCT1–116 and PCT3–116. Both PCT species increase early during endotoxemia but differ in their kinetics thereafter. The selective measurement of PCT species with different in vivo kinetics may be useful in improving PCT-guided therapies.
11
Li, Qing. "Interaction and Communication: An Examination of Gender Differences in Elementary Student Mathematics and Science Learning Using CMC." Journal of Educational Technology Systems 30, no. 4 (June 2002): 403–26. http://dx.doi.org/10.2190/03q1-v1n4-pctf-xw0y.
Full textAbstract:
In this study, gender difference is explored from two perspectives: 1) student interaction patterns, and 2) communication patterns. The data used is collected from a fifth- and sixth- grade classroom in an inner city elementary school in Toronto, Ontario. There were 24 students (12 male students and 12 female students) in the class. First, the interaction patterns of students' mathematics and science learning were examined in terms of turn taking, conversation initiating, and conversation following. The results of the analysis show that male students still take more turns in this CMC setting. Male and female students are equally likely to initialize topics. Those male generated messages were significantly less likely to be followed than those female generated messages. But male and female students are just as likely to follow and support previous messages in this CMC setting. Based on these results, gender differences are then examined with respect to student communication pattern. Communication is explored in terms of language functions. The analysis of the data indicates that female students tend to request more information, but offer fewer explanations and opinions than male students do. With respect to connected initiating messages, female students are found to be similar to male students in the use of the five language functions. However, moving to conversation development, two significant gender differences are found in student use of language functions: female students tend to request more information but offer fewer explanations than male students do in those followed-up messages.
12
Hernández, Pedro, Armando Lucero-Acuña, Cindy Alejandra Gutiérrez-Valenzuela, Ramón Moreno, and Reynaldo Esquivel. "Systematic evaluation of pH and thermoresponsive poly(n-isopropylacrylamide-chitosan-fluorescein) microgel." e-Polymers 17, no. 5 (August 28, 2017): 399–408. http://dx.doi.org/10.1515/epoly-2016-0328.
Full textAbstract:
AbstractThe interesting properties of stimuli-responsive polymers lead to a wide range of possibilities in design and engineering of functional material for the biomedical application. A systematic approach focused on the evaluation of the physical properties of multiresponse (pH and temperature) PNIPAM was reported in this work. The effect of three different molar ratios of poly(n-isopropylacrylamide): chitosan (1:49, 1:99 and 1:198) were evaluated and labeled correspondingly as PC1F, PC2F, and PC3F. An increase in the lower critical solution temperature (LCST) of sample PC1F (34°C) was observed by differential scanning calorimetry (DSC). The presence of low molecular weight chitosan (LMWC) full-interpenetrating polymer (Full-IPN) segments in poly(n-isopropylacrylamide) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The hydrogel’s water capture was analyzed by two models of swelling, the power law model and a model that considers the relaxation of polymeric chains of the hydrogel, finding good correlations with experimental data in both cases. Sample PC3F resulted with higher swellability, increasing the weight of the hydrogel around seven times. Hydrogel pH-sensibility was confirmed placing the samples at different pH environments, with an apparent increase in swellability for acidic conditions, confirming the highest swellability for sample PC3F, due to hydrogen bonds boosted by chitosan high molar ratio. Based on these results, the hydrogel obtained has potential as a thermo-pH triggered hydrogel in drug delivery applications.
13
Ramos, Enrique, Jose E. Roman, Agustín Abarca, Rafael Miró, and Juan A. Bermejo. "Control rod drop transient analysis with the coupled parallel code pCTF-PARCSv2.7." Annals of Nuclear Energy 87 (January 2016): 308–17. http://dx.doi.org/10.1016/j.anucene.2015.09.016.
Full text
14
Bleeker, Arno J., Mark H. F. Overwijk, and Max T. Otten. "Practical Correction of Three Fold Astigmatism in the Philips CM TEM." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 418–19. http://dx.doi.org/10.1017/s0424820100164556.
Full textAbstract:
With the improvement of the optical properties of the modern TEM objective lenses the point resolution is pushed beyond 0.2 nm. The objective lens of the CM300 UltraTwin combines a Cs of 0. 65 mm with a Cc of 1.4 mm. At 300 kV this results in a point resolution of 0.17 nm. Together with a high-brightness field-emission gun with an energy spread of 0.8 eV the information limit is pushed down to 0.1 nm. The rotationally symmetric part of the phase contrast transfer function (pctf), whose first zero at Scherzer focus determines the point resolution, is mainly determined by the Cs and defocus. Apart from the rotationally symmetric part there is also the non-rotationally symmetric part of the pctf. Here the main contributors are not only two-fold astigmatism and beam tilt but also three-fold astigmatism. The two-fold astigmatism together with the beam tilt can be corrected in a straight-forward way using the coma-free alignment and the objective stigmator. However, this only works well when the coefficient of three-fold astigmatism is negligible compared to the other aberration coefficients. Unfortunately this is not generally the case with the modern high-resolution objective lenses. Measurements done at a CM300 SuperTwin FEG showed a three fold-astigmatism of 1100 nm which is consistent with measurements done by others. A three-fold astigmatism of 1000 nm already sinificantly influences the image at a spatial frequency corresponding to 0.2 nm which is even above the point resolution of the objective lens. In principle it is possible to correct for the three-fold astigmatism a posteriori when through-focus series are taken or when off-axis holography is employed. This is, however not possible for single images. The only possibility is then to correct for the three-fold astigmatism in the microscope by the addition of a hexapole corrector near the objective lens.
15
Tomita, T., S. Katoh, H. Kitajima, Y. Kokubo, and Y. Ishida. "Development of Field-Emission Gun for High-Voltage Electron Microscope." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 94–95. http://dx.doi.org/10.1017/s0424820100134065.
Full textAbstract:
It is well known that the combination of a field emission gun (FEG) and a conventional transmission electron microscope (CTEM) is extremely important for nanometer area analysis in analytical electron microscopy. However, the smaller illumination angle and reduced energy spread of FEG than those of a conventional electron gun (W hair pin filament or LaB6) give a slowly damping envelop function in phase contrast transfer function (PCTF). Thus the FEG ensures application not only to analytical microscopy but also to high resolution electron microscopy to improve the information limit.In a high voltage electron microscope (above 200 kV), high-speed vacuum pumps have to be provided below the acceleration tube to get an ultra high vacuum (UHV) around the field emission tip located at the top of the acceleration tube. However, this method is not always the best way to provide UHV because of the poor vacuum conductance caused by the electrodes inside the acceleration tube.
16
Geipel, T., and W. Mader. "Practical aspects about hollow-cone imaging." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 576–77. http://dx.doi.org/10.1017/s0424820100139251.
Full textAbstract:
Hollow-cone imaging (HCI) as a possibility to improve the resolution of a TEM has already been proposed in the late 40ties and besides others, there have been extensive hollow-cone experiments 10 years back using a low resolution TEM with a non-tilt specimen holder. In a recent paper the optimum imaging parameters for HCI were determined leading to an improvement of the resolution by a factor of two. However, there are contrast limitations and experimental problems for HCI which were only partly considered in Ref. and which will be discussed in this paper for a modern electron microscope. Preliminary experiments were performed which are not shown in the abstract.In Fig. 1 ∫ ct f(u)du is plotted versus defocus Δ f for different cone radii Θc and a fixed aperture radius Θo = 1/δ = 5 nm-1 (ct f is the phase contrast transfer function (PCTF) for HCI and δ = 0.2 nm is the resolution of a CM30 supertwin microscope).
17
Oikawa, T., H. Kosugi, F. Hosokawa, D. Shindo, and M. Kersker. "Evaluation method for imaging plate resolution by means of phase contrast transfer function." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 662–63. http://dx.doi.org/10.1017/s0424820100139688.
Full textAbstract:
Evaluation of the resolution of the Imaging Plate (IP) has been attempted by some methods. An evaluation method for IP resolution, which is not influenced by hard X-rays at higher accelerating voltages, was proposed previously by the present authors. This method, however, requires truoblesome experimental preperations partly because specially synthesized hematite was used as a specimen, and partly because a special shape of the specimen was used as a standard image. In this paper, a convenient evaluation method which is not infuenced by the specimen shape and image direction, is newly proposed. In this method, phase contrast images of thin amorphous film are used.Several diffraction rings are obtained by the Fourier transformation of a phase contrast image of thin amorphous film, taken at a large under focus. The rings show the spatial-frequency spectrum corresponding to the phase contrast transfer function (PCTF). The envelope function is obtained by connecting the peak intensities of the rings. The evelope function is offten used for evaluation of the instrument, because the function shows the performance of the electron microscope (EM).
18
WIESNER, I., D. WIESNEROVÁ, and E. TEJKLOVÁ. "Effect of anchor and core sequence in microsatellite primers on flax fingerprinting patterns." Journal of Agricultural Science 137, no. 1 (August 2001): 37–44. http://dx.doi.org/10.1017/s0021859601001162.
Full textAbstract:
The aim of this study was to select the best arrangements of MP–PCR (microsatellite-primed PCR) for routine large-scale fingerprinting of flax cultivars. We found optimum PCR conditions for the application of five previously published primers (PCT1–PCT5) to flax cultivar fingerprinting. We modified to optimum MP–PCR which was targeted to flax tetrameric [GATA] microsatellite loci specified by primer PCT6. We found that after a reamplification PCR step was involved we were able to generate highly discriminating fingerprinting patterns, which distinguished all eight flax cultivars individually. In particular primers 3PCT1 and 3PCT2 were promising for future large-scale fingerprinting due to the production of most polymorphic bands. Increasing annealing temperature within a temperature profile helped to generate new polymorphisms within flax microsatellite patterns especially with primer 3PCT2. Using this primer we succeeded in generating new polymorphic bands after increasing annealing temperature from 55 °C to 60 °C, and to 65 °C. A cluster analysis of flax cultivars was performed based on microsatellite data. The core group of eight flax cultivars was clustered into two homogeneous subclusters. A lower level of cultivar clustering within subclusters was not detected.
19
Ramos, Enrique, Jose E. Roman, Agustín Abarca, Rafael Miró, Juan A. Bermejo, Alberto Ortego, and Jose M. Posada. "Verification of the Parallel Pin-Wise Core Simulator pCTF/PARCSv3.2 in Operational Control Rod Drop Transient Scenarios." Nuclear Science and Engineering 187, no. 3 (June 19, 2017): 254–67. http://dx.doi.org/10.1080/00295639.2017.1320892.
Full text
20
Dippel, Andrew B., Gregory M. Olenginski, Nicole Maurici, Melanie T. Liskov, Scott H. Brewer, and Christine M. Phillips-Piro. "Probing the effectiveness of spectroscopic reporter unnatural amino acids: a structural study." Acta Crystallographica Section D Structural Biology 72, no. 1 (January 1, 2016): 121–30. http://dx.doi.org/10.1107/s2059798315022858.
Full textAbstract:
The X-ray crystal structures of superfolder green fluorescent protein (sfGFP) containing the spectroscopic reporter unnatural amino acids (UAAs) 4-cyano-L-phenylalanine (pCNF) or 4-ethynyl-L-phenylalanine (pCCF) at two unique sites in the protein have been determined. These UAAs were genetically incorporated into sfGFP in a solvent-exposed loop region and/or a partially buried site on the β-barrel of the protein. The crystal structures containing the UAAs at these two sites permit the structural implications of UAA incorporation for the native protein structure to be assessed with high resolution and permit a direct correlation between the structure and spectroscopic data to be made. The structural implications were quantified by comparing the root-mean-square deviation (r.m.s.d.) between the crystal structure of wild-type sfGFP and the protein constructs containing either pCNF or pCCF in the local environment around the UAAs and in the overall protein structure. The results suggest that the selective placement of these spectroscopic reporter UAAs permits local protein environments to be studied in a relatively nonperturbative fashion with site-specificity.
21
Lwoga, Noel Biseko. "Local collaboration network in management of built heritage." Journal of Cultural Heritage Management and Sustainable Development 7, no. 3 (August 21, 2017): 226–43. http://dx.doi.org/10.1108/jchmsd-05-2016-0034.
Full textAbstract:
Purpose The purpose of this paper is to apply stakeholder and network theories to explore local collaboration network, its structural features and their implications to the management of the built heritage. Design/methodology/approach This paper applies stakeholder and network analyses. It follows a case study approach using multiple data collection methods such as the documentary analysis, and semi-structured interviews with 22 local stakeholders in the Pangani Conservation Task Force’s (PCTF’s) in Tanzania. It subjects the data to thematic analysis through the NVivo program, and to network analysis through the UCINET and NETDRAW programs. Findings This paper indicates that the PCTF is composed of heterogeneous stakeholders who are networked in a less cohesive structure, whereby the collaboration system is dominated by conservation actors while marginalizing tourism and some local resident groups. This structure, despite its inherent disadvantages, was found to enhance the achievement of PCTF’s conservation goals in the short term. Research limitations/implications The single case study approach makes generalizing beyond the study area difficult. Nevertheless, the findings raise relevant issues for further multiple-case investigations on collaboration systems from a built heritage perspective. Originality/value This paper is the first insightful exploration of the stakeholder collaboration system in the local built heritage site in Tanzania, using both the stakeholder and network analyses. It presents a useful tool for organizational analysis in heritage management and makes a good argument for its use to better understand participatory management.
22
Hammel, M., H. Kohl, and H. Rose. "Information Enhancement in the STEM by Employing a Multiple-Signals Imaging Procedure." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 120–21. http://dx.doi.org/10.1017/s042482010017935x.
Full textAbstract:
When performing high resolution bright field imaging of weak phase objects in a STEM, all electrons falling onto the specimen are reaching the detector plane. Hence, there is no information available about the object function if the detector covers the entire cone of the unscattered electrons. Nevertheless, the current density within this cone differs from being constant because of constructive and destructive interference between the elastically scattered and unscattered electrons. In order to get a phase contrast signal, one can use a circular detector subtending a small aperture angle. However, this method discards a lot of electrons which have been scattered by the specimen and therefore carry information about its structure. In principle, all of them should be subject to investigation. To achieve this, the detector region must be divided in such a way that regions with constructive and destructive interference, respectively, form different signals. Since these signals are registered separately, they can be appropriately combined to extract the information of interest.Several methods have been proposed for optimizing the detector configuration of the multiple signals imaging mode in the last fifteen years. Splitting the detector into semicircles yields differential phase contrast and explores the gradient of the object function. Integrating the signal of such a detector in the direction perpendicular to the split gives good contrast transfer at small spatial frequencies at least at high doses. On the other hand, a division of the circular detector in rings enables one to improve the transfer of high spatial frequencies without any zeroes in the phase contrast transfer function (PCTF, [2]). Both detector arrangements have been combined. Recently, a free configurational detector has been developed and tested. The configuration of ref. [3] has been improved by M. Haider et al. so that the possibilities in creating zones of different shapes have increased very much.
23
Sohrabi, M., and F. Ebrahiminezhad. "EFFECTS OF ACTIVATED-CARBON-FABRIC PARAMETERS ON RESPONSE OF A NEW POLYCARBONATE-BASED INDIVIDUAL AND ENVIRONMENTAL RADON MONITOR." Radiation Protection Dosimetry 184, no. 3-4 (April 26, 2019): 466–69. http://dx.doi.org/10.1093/rpd/ncz098.
Full textAbstract:
Abstract A new multi-purpose polycarbonate track detector (PCTD)/activated-carbon-fabric (ACF) radon monitor has been recently developed in our laboratory, a basic design of which was used for parametric studies. One 500 μm thick PCTD (3 cm x 3 cm) is used bare for detecting alphas from radon and progeny directly from air and another PCTD (3 cm x 3 cm) covered by an ACF layer (PCTD/ACF) to enhance the PCTD response by radon adsorption on its carbon active sites. The PCTDs were processed by 50 Hz−2 kV electrochemical etching method. The ACF/PCTD sensitivity was enhanced in respect to the PCTD/bare with an amplification factor (AF) defined as ratio of track density on PCTD under ACF to that of PCTD bare. Many ACF-related parameters studied affect the PCTD/ACF response among them thermal annealing of ACF, ACF thickness and distance of ACF layer to the PCTD are reported and discussed in this paper.
24
Jin, Yetao, Shelya X. Zeng, Hunjoo Lee, and Hua Lu. "MDM2 Mediates p300/CREB-binding Protein-associated Factor Ubiquitination and Degradation." Journal of Biological Chemistry 279, no. 19 (February 9, 2004): 20035–43. http://dx.doi.org/10.1074/jbc.m309916200.
Full textAbstract:
We recently reported that MDM2, a negative feedback regulator of the tumor suppressor p53, inhibits p300/CREB-binding protein-associated factor (PCAF)-mediated p53 acetylation. Our further study showed that MDM2 also regulates the stability of PCAF. MDM2 ubiquitinated PCAFin vitroand in cells. PCAF ubiquitination occurred at the N terminus and in the nucleus, as the nuclear localization signal sequence-deletion mutant of MDM2, which localized in the cytoplasm and degraded p53, was unable to degrade nuclear PCAF. Restriction of PCAF in the nucleus by leptomycin B did not affect MDM2-mediated PCAF degradation. Consistently, overexpression of MDM2 in p53 null cells caused the reduction of the protein level of PCAF, but not the mRNA level. Conversely, PCAF levels were higher in MDM2-deficient mousep53-/-/mdm2-/-embryonic fibroblast (MEF) cells than that in MDM2-containing MEF cells. Furthermore, MDM2 reduced the half-life of PCAF by 50%. These results demonstrate that MDM2 regulates the stability of PCAF by ubiquitinating and degrading this protein.
25
Unal, Ersin Selcuk, Rongbao Zhao, and I. David Goldman. "Role of the glutamate 185 residue in proton translocation mediated by the proton-coupled folate transporter SLC46A1." American Journal of Physiology-Cell Physiology 297, no. 1 (July 2009): C66—C74. http://dx.doi.org/10.1152/ajpcell.00096.2009.
Full textAbstract:
The proton-coupled folate transporter (PCFT) SLC46A1 mediates uphill folate transport into enterocytes in proximal small intestine coupled to the inwardly directed proton gradient. Hereditary folate malabsorption is due to loss-of-function mutations in the PCFT gene. This study addresses the functional role of conserved charged amino acid residues within PCFT transmembrane domains with a detailed analysis of the PCFT E185 residue. D156A-, E185A-, E232A-, R148A-, and R376A-PCFT mutants lost function at pH 5.5, as assessed by transient transfection in folate transport-deficient HeLa cells. At pH 7.4, function was preserved only for E185A-PCFT. Loss of function for E185A-PCFT at pH 5.5 was due to an eightfold decrease in the [3H]methotrexate (MTX) influx Vmax; the MTX influx Ktwas identical to that of wild-type (WT)-PCFT (1.5 μM). Consistent with the intrinsic functionality of E185A-PCFT, [3H]MTX influx at pH 5.5 or 7.4 was trans-stimulated in cells preloaded with nonlabeled MTX or 5-formyltetrahydrofolate. Replacement of E185 with Leu, Cys, His, or Gln resulted in a phenotype similar to E185A-PCFT. However, there was greater preservation of activity (∼38% of WT) for the similarly charged E185D-PCFT at pH 5.5. All E185 substitution mutants were biotin accessible at the plasma membrane at a level comparable to WT-PCFT. These observations suggest that the E185 residue plays an important role in the coupled flows of protons and folate mediated by PCFT. Coupling appears to have a profound effect on the maximum rate of transport, consistent with augmentation of a rate-limiting step in the PCFT transport cycle.
26
Xie, Qingtong, Xudong Zheng, Liuting Li, Liqun Ma, Qihui Zhao, Shiyuan Chang, and Lijun You. "Effect of Curcumin Addition on the Properties of Biodegradable Pectin/Chitosan Films." Molecules 26, no. 8 (April 8, 2021): 2152. http://dx.doi.org/10.3390/molecules26082152.
Full textAbstract:
A pectin/chitosan matrix-loaded curcumin film (PCCF) with a deep eutectic solvent (DES) as the solvent and plasticizer was prepared in this study. Different quantities of curcumin (identified as PCCF-0, PCCF-1, PCCF-2. PCCF-3) were loaded on the pectin/chitosan film in order to evaluate their effects on the film properties. Results showed that curcumin could interact with the pectin/chitosan matrix and form a complex three-dimensional network structure. PCCF could promote the thickness, tensile strength, thermal properties, antioxidant and antiseptic capacities, but deteriorate the light transmission and elongation at the same time. The addition of curcumin would change the color of the film, without significantly affecting the moisture content. The tensile strength of PCCF-3 reached the maximum value of 3.75 MPa, while the elongation decreased to 10%. Meanwhile, the water-resistance properties of PCCF-3 were significantly promoted by 8.6% compared with that of PCCF-0. Furthermore, PCCF showed remarkable sustained antioxidant activities in a dose-dependent manner. PCCF-3 could inhibit DPPH and ABTS free radicals by 58.66% and 29.07%, respectively. It also showed antiseptic capacity on fresh pork during storage. Therefore, curcumin addition could improve the barrier, mechanical, antioxidant and antiseptic properties of the polysaccharide-based film and PCCF has the potential to be used as a new kind of food packaging material in the food industry.
27
Jiang, Hua, Hanxin Lu, R. Louis Schiltz, Cynthia A. Pise-Masison, Vasily V. Ogryzko, Yoshihiro Nakatani, and John N. Brady. "PCAF Interacts with Tax and Stimulates Tax Transactivation in a Histone Acetyltransferase-Independent Manner." Molecular and Cellular Biology 19, no. 12 (December 1, 1999): 8136–45. http://dx.doi.org/10.1128/mcb.19.12.8136.
Full textAbstract:
ABSTRACT Recent studies have shown that the p300/CREB binding protein (CBP)-associated factor (PCAF) is involved in transcriptional activation. PCAF activity has been shown strongly associated with histone acetyltransferase (HAT) activity. In this report, we present evidence for a HAT-independent transcription function that is activated in the presence of the human T-cell leukemia virus type 1 (HTLV-1) Tax protein. In vitro and in vivo GST-Tax pull-down and coimmunoprecipitation experiments demonstrate that there is a direct interaction between Tax and PCAF, independent of p300/CBP. PCAF can be recruited to the HTLV-1 Tax responsive element in the presence of Tax, and PCAF cooperates with Tax in vivo to activate transcription from the HTLV-1 LTR over 10-fold. Point mutations at Tax amino acid 318 (TaxS318A) or 319 to 320 (Tax M47), which have decreased or no activity on the HTLV-1 promoter, are defective for PCAF binding. Strikingly, the ability of PCAF to stimulate Tax transactivation is not solely dependent on the PCAF HAT domain. Two independent PCAF HAT mutants, which knock out acetyltransferase enzyme activity, activate Tax transactivation to approximately the same level as wild-type PCAF. In contrast, p300 stimulation of Tax transactivation is HAT dependent. These studies provide experimental evidence that PCAF contains a coactivator transcription function independent of the HAT activity on the viral long terminal repeat.
28
Shin, Daniel Sanghoon, Rongbao Zhao, Enghui H. Yap, Andras Fiser, and I. David Goldman. "A P425R mutation of the proton-coupled folate transporter causing hereditary folate malabsorption produces a highly selective alteration in folate binding." American Journal of Physiology-Cell Physiology 302, no. 9 (May 1, 2012): C1405—C1412. http://dx.doi.org/10.1152/ajpcell.00435.2011.
Full textAbstract:
Proton-coupled folate transporter (PCFT) mediates folate intestinal absorption and transport across the choroid plexus, processes defective in subjects with hereditary folate malabsorption (HFM). PCFT is also widely expressed in human solid tumors where it contributes to the transport of pemetrexed and other antifolates. This study defines the basis for the functional changes due to a P425R mutation detected in a subject with HFM. Among various substitutions, only positively charged mutants (P425R and P425K) lost function but in a highly selective manner. Transport of reduced folates mediated by P425R-PCFT was virtually abolished; the methotrexate influx Kt was increased fivefold (from 2 to 10 μM). In contrast, the pemetrexed influx Kt mediated by P425R-PCFT was decreased 30% compared with wild-type (WT)-PCFT. Methotrexate inhibition of pemetrexed influx was competitive with a Ki for WT-PCFT comparable to its influx Kt. However, the methotrexate influx Ki for P425R-PCFT was ∼15-fold higher than the WT-PCFT influx Kt and threefold higher than the methotrexate influx Kt for the P425R-PCFT mutant. The confirmed secondary structure and homology modeling place the P425 residue at the junction of the 6th external loop and 12th transmembrane domain, remote from the aqueous translocation pathway, a prediction confirmed by the failure to label P425C-PCFT with N-biotinylaminoethyl methanethiosulfonate-biotin and the absence of inhibition of P425C-PCFT function by water-soluble sulfhydryl reagents. Hence, despite its location, the P425R-PCFT mutation produces a conformational change that fully preserves pemetrexed binding but markedly impairs binding of methotrexate and other folates to the carrier.
29
Sunami, Yoshitaka, Marito Araki, Akihiro Ito, Yumi Hironaka, Minoru Yoshida, Akimichi Ohsaka, and Norio Komatsu. "Histone Acetyltransferase Pcaf Is Required for ATRA-Induced Granulocytic Differentiation in Acute Promyelocytic Leukemia Cells." Blood 124, no. 21 (December 6, 2014): 617. http://dx.doi.org/10.1182/blood.v124.21.617.617.
Full textAbstract:
Abstract Differentiation therapy with All-trans retinoic acid (ATRA) improves the treatment outcome of acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia (AML); however, its molecular mechanism remains elusive. We have previously reported that inhibition of NAD-dependent histone deacetylase SIRT2 induces granulocytic differentiation in APL cells (PLOS ONE. 2013; 8(2): e57633), suggesting a possible involvement of protein acetylation in the differentiation of APL cells by ATRA. To assess this possibility, in the present study, we examined expression of major histone-acetyltrasnferases such as GCN5, PCAF, and CBP/p300 upon ATRA-treatment, and found that PCAF-expression was dramatically increased at mRNA (1.8 to 7 fold, Figure 1A) as well as protein levels in NB4, HL-60, and APL primary cells. Consistent with this, PCAF mRNA expression was greatly induced (10 to 40 fold) in the bone marrow of APL patients who received ATRA-containing treatment (Figure 1B). A search in the public expression database revealed that PCAF-expression in bone marrow was generally reduced in not only APL but also other acute hematologic malignancies such as AML and acute lymphoblastic leukemia (ALL) (healthy donor; n = 74, APL; n=37, AML; n=505, ALL; n=750, healthy donor vs. AML, p < 0.001, healthy donor vs. APL, p < 0.001, healthy donor vs. ALL, p < 0.001, adopted from oncomine database). Interestingly, the reduction of PCAF-expression was much more evident in acute than chronic hematologic malignancies such as chronic myeloid leukemia (CML) and myelodysplastic syndrome (MDS) (CML; n = 76, MDS; n=206), suggesting that PCAF reduction is related to a blockade of proper differentiation in malignant cells. Based on these findings we hypothesized that PCAF plays an important role in ATRA-induced APL cell differentiation. To prove this, we performed a loss-of-function assay using lentivirus vectors expressing 3 independent shRNA against PCAF or non-targeting shRNA (control) (Figure 1C). When PCAF was knocked down in HL-60 cells, these cells failed to differentiate into granulocytes with ATRA-treatment (31.9±11.9% vs. 4.9±2.2%, 5.2±0.7%, 8.6±3.7%, CD11b positive cells, control vs. 3 independent PCAF shRNA) (Figure 1C). Moreover, transduction of PCAF shRNA or non-target shRNA to primary APL cells made cells resistant to ATRA-induced granulocytic differentiation (data not shown), suggesting that PCAF is required for the ATRA-induced granulocytic differentiation in APL cells. To further investigate how PCAF promotes APL cell differentiation upon ATRA-treatment, we performed an acetylome analysis to identify a downstream molecule whose activity is regulated by PCAF through acetylation. We pulled-down acetylated proteins using anti-acetylated lysine antibody from cell extracts prepared 3 or 24 hours after either mock- or ATRA-treatment, and identified 5 proteins preferentially acetylated by ATRA-treatment including histone H3, which is a known acetylation target of PCAF. These results strongly support our hypothesis that upon ATRA-treatment, PCAF induction and subsequent acetylation of PCAF substrates promotes APL cell differentiation. More detailed understanding of PCAF-dependent APL cell differentiation may lead to the development of differentiation therapy against not only APL but also other AML. Figure 1 (A) PCAF mRNA induction in ATRA-treated NB4, HL-60, and APL primary cells. (B) PCAF induction in the bone marrow of APL patients during the ATRA-containing chemotherapy. Day 1 represents the mRNA level prior to the treatment. (C) PCAF knocked-down in HL-60 cells by 3 independent shRNA against PCAF or non-targeting shRNA (control) (Upper left). PCAF knocked-down cells lack a capacity to differentiate into granulocytes (CD11b positive cells) by ATRA-treatment (***; p<0.001, n=3) (lower left, and right). Figure 1. (A) PCAF mRNA induction in ATRA-treated NB4, HL-60, and APL primary cells. (B) PCAF induction in the bone marrow of APL patients during the ATRA-containing chemotherapy. Day 1 represents the mRNA level prior to the treatment. (C) PCAF knocked-down in HL-60 cells by 3 independent shRNA against PCAF or non-targeting shRNA (control) (Upper left). PCAF knocked-down cells lack a capacity to differentiate into granulocytes (CD11b positive cells) by ATRA-treatment (***; p<0.001, n=3) (lower left, and right). Disclosures No relevant conflicts of interest to declare.
30
Reyes-Darias, José A., Yiling Yang, Victor Sourjik, and Tino Krell. "Correlation between signal input and output in PctA and PctB amino acid chemoreceptor ofPseudomonas aeruginosa." Molecular Microbiology 96, no. 3 (March 4, 2015): 513–25. http://dx.doi.org/10.1111/mmi.12953.
Full text
31
Sachdeva M.D.S., Suresh K., Sakshi Mehta B.D.S., Husain Sabir M.D.S., and Purnendu Rout M.D.S. "Peripheral Cemento-Ossifying Fibroma with Uncommon Clinical Presentation: A Case Report." Odovtos - International Journal of Dental Sciences 20, no. 1 (October 23, 2017): 17–23. http://dx.doi.org/10.15517/ijds.v0i0.31007.
Full textAbstract:
Peripheral cemento-ossifying fibroma (PCOF) is a reactive gingival over growth, occurring frequently in the maxillary anterior region of teenage and young females. Peripheral cemento-ossifying fibroma (PCOF) is supposed to be originating from periosteum and/or periodontal ligament. A large number of factors have been implicated in the pathogenesis of PCOF, which includes trauma, local irritation, calculus and hormonal disturbances. The definitive diagnosis of PCOF is based upon its clinical, radiological and histological features. Because of the high recurrence rate (8-20%) of PCOF, a close post-operative follow-up is required. Herewith, we are presenting a case of PCOF in 24-year old female patient at an uncommon location.
32
Sachdeva M.D.S., Suresh K., Sakshi Mehta B.D.S., Husain Sabir M.D.S., and Purnendu Rout M.D.S. "Peripheral Cemento-Ossifying Fibroma with Uncommon Clinical Presentation: A Case Report." Odovtos - International Journal of Dental Sciences 20, no. 1 (October 23, 2017): 17–23. http://dx.doi.org/10.15517/ijds.v20i1.31007.
Full textAbstract:
Peripheral cemento-ossifying fibroma (PCOF) is a reactive gingival over growth, occurring frequently in the maxillary anterior region of teenage and young females. Peripheral cemento-ossifying fibroma (PCOF) is supposed to be originating from periosteum and/or periodontal ligament. A large number of factors have been implicated in the pathogenesis of PCOF, which includes trauma, local irritation, calculus and hormonal disturbances. The definitive diagnosis of PCOF is based upon its clinical, radiological and histological features. Because of the high recurrence rate (8-20%) of PCOF, a close post-operative follow-up is required. Herewith, we are presenting a case of PCOF in 24-year old female patient at an uncommon location.
33
Lim, Yongwoon, Anna Jeong, Duk-Hwa Kwon, Yeong-Un Lee, Young-Kook Kim, Youngkeun Ahn, Taewon Kook, Woo-Jin Park, and Hyun Kook. "P300/CBP-Associated Factor Activates Cardiac Fibroblasts by SMAD2 Acetylation." International Journal of Molecular Sciences 22, no. 18 (September 14, 2021): 9944. http://dx.doi.org/10.3390/ijms22189944.
Full textAbstract:
Various heart diseases cause cardiac remodeling, which in turn leads to ineffective contraction. Although it is an adaptive response to injury, cardiac fibrosis contributes to this remodeling, for which the reactivation of quiescent myofibroblasts is a key feature. In the present study, we investigated the role of the p300/CBP-associated factor (PCAF), a histone acetyltransferase, in the activation of cardiac fibroblasts. An intraperitoneal (i.p.) injection of a high dose (160 mg/kg) of isoproterenol (ISP) induced cardiac fibrosis and reduced the amount of the PCAF in cardiac fibroblasts in the mouse heart. However, the PCAF activity was significantly increased in cardiac fibroblasts, but not in cardiomyocytes, obtained from ISP-administered mice. An in vitro study using human cardiac fibroblast cells recapitulated the in vivo results; an treatment with transforming growth factor-β1 (TGF-β1) reduced the PCAF, whereas it activated the PCAF in the fibroblasts. PCAF siRNA attenuated the TGF-β1-induced increase in and translocation of fibrosis marker proteins. PCAF siRNA blocked TGF-β1-mediated gel contraction and cell migration. The PCAF directly interacted with and acetylated mothers against decapentaplegic homolog 2 (SMAD2). PCAF siRNA prevented TGF-β1-induced phosphorylation and the nuclear localization of SMAD2. These results suggest that the increase in PCAF activity during cardiac fibrosis may participate in SMAD2 acetylation and thereby in its activation.
34
Laftah, Abas H., Gladys O. Latunde-Dada, Sarah Fakih, Robert C. Hider, Robert J. Simpson, and Andrew T. McKie. "Haem and folate transport by proton-coupled folate transporter/haem carrier protein 1 (SLC46A1)." British Journal of Nutrition 101, no. 8 (September 10, 2008): 1150–56. http://dx.doi.org/10.1017/s0007114508066762.
Full textAbstract:
Haem carrier protein 1 (HCP1) was originally identified and characterised as a mammalian haem transporter. However, recent evidence has shown that it is also a proton-coupled folate transporter (PCFT) and mutations in the gene cause hereditary folate deficiency in humans. We therefore investigated haem and folate transport characteristics of PCFT/HCP1 bothin vivoandin vitroin CD-1 mice and in the presence or absence of a blocking antibody for PCFT/HCP1, and also in cultured cells (which express PCFT/HCP1 endogenously) to elucidate the specificity and selectivity of PCFT/HCP1. Thein vivostudy showed that the addition of folic acid inhibited59Fe-labelled haem transport in hypoxic mice but had no effect in normal mice. Usingin vitromethods, the results showed increased [3H]folate uptake into everted duodenum from hypoxic mice but uptake was reduced by the addition of haem or PCFT/HCP1 antibodies to the medium. Caco-2 cells transiently transfected with small interfering RNA (siRNA) PCFT/HCP1 duplex oligos resulted in a 69 % reduction in PCFT/HCP1 mRNA when compared with the control siRNA. Both haem and folate uptake were significantly (P < 0·05) reduced in cells transfected with PCFT/HCP1 siRNA; however, the magnitude of reduction with folic acid uptake was greater (48 %) than that of haem (22·5 %). Overall the data support PCFT/HCP1 as a primary folate transporter with a lower affinity for haem. PCFT/HCP1 could therefore play a physiological role in Fe nutrition and the data highlight the potential for the interaction of folate and haem at the level of intestinal absorption.
35
Chongprakobkit, Suchada, and Wanpen Tachaboonyakiat. "A Thermal Controlled Release of Naproxen from Sodium Phosphorylated Chitosan Nanoemulsion." Advanced Materials Research 701 (May 2013): 217–21. http://dx.doi.org/10.4028/www.scientific.net/amr.701.217.
Full textAbstract:
The aim of this research was to control the delivery of naproxen from emulsion-based sodium phosphorylated chitosan (PCTS) nanoparticles (PCTS nanoemulsion) by thermal stimulus. The dynamic light scattering and optical microscope results demonstrated that the droplet size of emulsion-based nanoparticles was sensitive to temperature. The PCTS nanoemulsion exhibited the droplet size around 230 nm at 30°C. Emulsion droplets were increased in their size over critical temperature of around 60°C. Besides, the droplet size was reversible to 270 nm when the temperature decreased to 30°C. This indicated that the droplet size of PCTS nanoemulsion was sensitive to thermal stimulus. It might owe to molecular chain extension and rearrangement of PCTS at the interface of emulsion droplets. Therefore, the control release of naproxen from PCTS nanoemulsion via thermal stimulus was investigated.In vitrorelease study showed that the naproxen was released from PCTS nanoemulsion in high amount over critical temperature. These results indicated that the PCTS nanoemulsion exhibited a potential application as intelligent thermal sensitive drug carrier.
36
Songdej, Natthapol, Guangfen Mao, Deepak Voora, Lawrence E. Goldfinger, Fabiola Del Carpio-Cano, Rachel Myers, and Angara Koneti Rao. "PCTP (Phosphatidylcholine Transfer Protein) is Regulated By RUNX1 in Platelets/Megakaryocytes and is Associated with Adverse Cardiovascular Events." Blood 128, no. 22 (December 2, 2016): 365. http://dx.doi.org/10.1182/blood.v128.22.365.365.
Full textAbstract:
Abstract Transcription factor (TF) mutations are increasingly recognized to play a major role in inherited platelet abnormalities. RUNX1, a major hematopoietic TF, acts in a combinatorial manner with other TFs to regulate numerous megakaryocyte (MK)/platelet genes. Human RUNX1 haplodeficiency is associated with thrombocytopenia, platelet function defects, and increased leukemia risk. We have described a patient with multiple abnormalities in platelet aggregation and secretion responses with a heterozygous RUNX1 nonsense mutation (Sun et al Blood 2004; 103; 948-54). Transcript expression profiling of patient platelets (Sun et al J Thromb Haemost 2007; 5:146-54)showed several genes were significantly downregulated, including myosin light chain (MYL9), platelet factor 4 (PF4), protein kinase C-θ (PRCKQ), and 12-lipoxygenase (ALOX12); these have been shown by us to be regulated by RUNX1. The profiling data also showed 10-fold downregulation of phosphatidylcholine transfer protein (PCTP) gene (fold change ratio 0.09, p=0.02) in the patient compared with normal controls. PCTP regulates the intermembrane transfer of phosphatidylcholine (PC), a major plasma membrane phospholipid. Platelet PCTP expression is associated with increased platelet aggregation and calcium mobilization upon activation of protease-activated receptor 4 (PAR4) thrombin receptors in black subjects as compared to white subjects (Edelstein et al Nat Med 2013; 19:1609-16). Pharmacologic inhibition of PCTP decreased platelet aggregation in response to PAR4 agonist and siRNA knockdown of PCTP in megakaryocytic cells blunted calcium mobilization induced by PAR4 (Edelstein et al Nat Med 2013; 19:1609-16). Little is known regarding the regulation of PCTP in MKs/platelets and its role in cardiovascular events. Based on the decreased platelet PCTP expression in our patient, we pursued the hypothesis that PCTP is regulated by RUNX1 and contributes to cardiovascular events. Corrected total cellular immunofluorescence with anti-PCTP antibody showed significantly reduced platelet PCTP expression by 58% in our patient compared to a normal control. In silico analysis revealed 5 RUNX1 consensus binding sites up to ~ 1 kb of the PCTP 5' upstream region from ATG. To assess for interaction of RUNX1 with the PCTP promoter, chromatin immunoprecipitation (ChIP) assay with anti-RUNX1 antibody was performed using human erythroid leukemia (HEL) cells treated with phorbol 12-myristate 13-acetate (PMA) for 48 hours to induce megakaryocytic transformation. The ChIP studies showed RUNX1 binding to PCTP chromatin in the regions encompassing RUNX1 binding site 1 (-345/-340), site 3 (-632/-627), and encompassing sites 4 and 5 (-974/-969, -997/-992). Electrophoretic mobility shift assay (EMSA) using PMA-treated HEL cell nuclear extracts showed RUNX1 binding to DNA probes (28-37 bp) containing site 1 (-345/-340) and both sites 4 and 5 (-974/-969, -997/-992). PCTP mRNA and protein expression were increased with RUNX1 overexpression and reduced with RUNX1 knockdown in HEL cells, indicating that PCTP is regulated by RUNX1. To assess the clinical relevance of the findings, the relationship between RUNX1 and PCTP in peripheral blood RNA, and PCTP and death or myocardial infarction (MI) events were assessed in two separate patient cohorts (n = 587 total patients) with cardiovascular disease. RUNX1 is transcribed from two alternate promoters (P1 and P2) resulting in different isoforms. In both patient cohorts, there was strong correlation between RUNX1 and PCTP expression in a promoter specific manner. RUNX1 P1 probe sets were strongly and inversely correlated with PCTP expression (p < 0.0001), while the P2 probe sets were not. PCTP expression was associated with death or MI in both patient cohorts (odds ratio 2.1, 95% CI [1.61-2.95], P-value < 0.0001) independent of age, sex, race, platelet count, and cardiovascular risk factors. Conclusions: Our results provide evidence that PCTP is regulated by RUNX1 (potentially in a promoter specific manner), and that PCTP expression is associated with death or myocardial infarction in patients with cardiovascular disease. RUNX1 regulation of PCTP may play a role in the pathogenesis of platelet-mediated cardiovascular events. Disclosures No relevant conflicts of interest to declare.
37
Salojin, Konstantin V., Robert M. Cabrera, Weimei Sun, Wei Chun Chang, Colin Lin, Lindsay Duncan, Ken A. Platt, et al. "A mouse model of hereditary folate malabsorption: deletion of the PCFT gene leads to systemic folate deficiency." Blood 117, no. 18 (May 5, 2011): 4895–904. http://dx.doi.org/10.1182/blood-2010-04-279653.
Full textAbstract:
Abstract The human proton coupled folate transporter (PCFT) is involved in low pH-dependent intestinal folate transport. In this report, we describe a new murine model of the hereditary folate malabsorption syndrome that we developed through targeted disruption of the first 3 coding exons of the murine homolog of the PCFT gene. By 4 weeks of age, PCFT-deficient (PCFT−/−) mice developed severe macrocytic normochromic anemia and pancytopenia. Immature erythroblasts accumulated in the bone marrow and spleen of PCFT−/− mice and failed to differentiate further, showing an increased rate of apoptosis in intermediate erythroblasts and reduced release of reticulocytes. In response to the inefficient hematologic development, the serum of the PCFT−/− animals contained elevated concentrations of erythropoietin, soluble transferrin receptor (sCD71), and thrombopoietin. In vivo folate uptake experiments demonstrated a systemic folate deficiency caused by disruption of PCFT-mediated intestinal folate uptake, thus confirming in vivo a critical and nonredundant role of the PCFT protein in intestinal folate transport and erythropoiesis. The PCFT-deficient mouse serves as a model for the hereditary folate malabsorption syndrome and is the most accurate animal model of folate deficiency anemia described to date that closely captures the spectrum of pathology typical of this disease.
38
McEntyre, Kelsey, Matthew D. Curtner-Smith, and Deborah S. Baxter. "Negotiations Between Preservice Classroom Teachers and Students During a Physical Education Early Field Experience." Journal of Teaching in Physical Education 39, no. 1 (January 1, 2020): 69–77. http://dx.doi.org/10.1123/jtpe.2018-0267.
Full textAbstract:
Purpose: To describe the patterns of negotiation engaged in by preservice classroom teachers (PCTs) and their students during a physical education early field experience. Method: The participants were 16 PCTs enrolled in the early field experience. They taught a variety of content within six lessons to second- and fourth-grade students. Data were collected using six qualitative methods and analyzed using analytic induction and constant comparison. Results/Conclusions: Seven PCTs were relatively effective negotiators, whereas nine PCTs were relatively ineffective. The PCTs’ negotiation skills were influenced by their comfort with physical education, pedagogical knowledge, content knowledge, and pedagogical content knowledge. The negotiations initiated by the PCTs and their students were similar to those described in previous studies. The type and amount of student-initiated negotiation was influenced by their gender, age, skill level, and content taught. The implications for preparing PCTs to teach physical education are discussed.
39
Torbey, MT, RG Geocadin, AY Razumovsky, D. Rigamonti, and MA Williams. "Utility of CSF Pressure Monitoring to Identify Idiopathic Intracranial Hypertension without Papilledema in Patients with Chronic Daily Headache." Cephalalgia 24, no. 6 (June 2004): 495–502. http://dx.doi.org/10.1111/j.1468-2982.2004.00688.x.
Full textAbstract:
The aim of the present study was to report on the utility of continuous Pcsf monitoring in establishing the diagnosis of idiopathic intracranial hypertension without papilledema (IIHWOP) in chronic daily headache (CDH) patients. We report a series of patients ( n = 10) with refractory headaches and suspected IIHWOP referred to us for continuous Pcsf monitoring between 1991 and 2000. Pcsf was measured via a lumbar catheter and analysed for mean, peak, highest pulse amplitude and abnormal waveforms. A 1-2 day trial of continuous controlled CSF drainage (10 cc/h) followed Pcsf monitoring. Response to CSF drainage was defined as improvement in headache symptoms. Patients with abnormal waveforms underwent a ventriculoperitoneal (VPS) or lumboperitoneal (LPS) shunt insertion. All patients had normal resting Pcsf (8 ± 1 mmHg) defined as ICP < 15 mmHg. During sleep, all patients had B-waves and 90% had plateau waves or near plateau waves. All patients underwent either a VPS or LPS procedure. All reported improvement of their headache after surgery. Demonstration of pathological Pcsf patterns by continuous Pcsf monitoring was essential in confirming the diagnosis of IIHWOP, and provided objective evidence to support the decision for shunt surgery. Increased Pcsf was seen mostly during sleep and was intermittent, suggesting that Pcsf elevation may be missed by a single spot-check LP measurement. The similarity between IIHWOP and CDH suggests that continuous Pcsf monitoring in CDH patients may have an important diagnostic role that should be further investigated.
40
Xie, An-Yong, Vladimir P. Bermudez, and William R. Folk. "Stimulation of DNA Replication from the Polyomavirus Origin by PCAF and GCN5 Acetyltransferases: Acetylation of Large T Antigen." Molecular and Cellular Biology 22, no. 22 (November 15, 2002): 7907–18. http://dx.doi.org/10.1128/mcb.22.22.7907-7918.2002.
Full textAbstract:
ABSTRACT The PCAF and GCN5 acetyltransferases, but not p300 or CBP, stimulate DNA replication when tethered near the polyomavirus origin. Replication stimulation by PCAF and GCN5 is blocked by mutational inactivation of their acetyltransferase domains but not by deletion of sequences that bind p300 or CBP. Acetylation of histones near the polyomavirus origin assembled into chromatin in vivo is not detectably altered by expression of these acetyltransferases. PCAF and GCN5 interact with polyomavirus large T antigen in vivo, PCAF acetylates large T antigen in vitro, and large T-antigen acetylation in vivo is dependent upon the integrity of the PCAF acetyltransferase domain. These data suggest replication stimulation occurs through recruitment of large T antigen to the origin and acetylation by PCAF or GCN5.
41
Shin, Daniel Sanghoon, Sang Hee Min, Laura Russell, Rongbao Zhao, Andras Fiser, and I. David Goldman. "Functional roles of aspartate residues of the proton-coupled folate transporter (PCFT-SLC46A1); a D156Y mutation causing hereditary folate malabsorption." Blood 116, no. 24 (December 9, 2010): 5162–69. http://dx.doi.org/10.1182/blood-2010-06-291237.
Full textAbstract:
Abstract The proton-coupled folate transporter (PCFT; SLC46A1) mediates folate transport into enterocytes in the proximal small intestine; pcft loss-of-function mutations are the basis for hereditary folate malabsorption. The current study explored the roles of Asp residues in PCFT function. A novel, homozygous, loss-of-function mutation, D156Y, was identified in a child of Pakistani origin with hereditary folate malabsorption. Of the 6 other conserved Asp residues, only one, D109, is shown to be required for function. D156Y, along with a variety of other substitutions at this site (Trp, Phe, Val, Asn, or Lys), lacked function due to instability of the PCFT protein. Substantial function was preserved with Glu, Gly, and, to a lesser extent, with Ser, Thr, and Ala substitutions. This correlated with PCFT bio-tinylated at the cell surface. In contrast, all D109 mutants, including D109E, lacked function irrespective of pH (4.5, 5.5, and 7.4) or substrate concentration (0.5-100μM), despite surface expression comparable to wild-type PCFT. Hence, D156 plays a critical role in PCFT protein stability, and D109, located in the first intracellular loop between the second and third transmembrane domains, is absolutely required for PCFT function.
42
Pediconi, Natalia, Francesca Guerrieri, Stefania Vossio, Tiziana Bruno, Laura Belloni, Valeria Schinzari, Cecilia Scisciani, Maurizio Fanciulli, and Massimo Levrero. "hSirT1-Dependent Regulation of the PCAF-E2F1-p73 Apoptotic Pathway in Response to DNA Damage." Molecular and Cellular Biology 29, no. 8 (February 2, 2009): 1989–98. http://dx.doi.org/10.1128/mcb.00552-08.
Full textAbstract:
ABSTRACT The NAD+-dependent histone deacetylase hSirT1 regulates cell survival and stress responses by inhibiting p53-, NF-κB-, and E2F1-dependent transcription. Here we show that the hSirT1/PCAF interaction controls the E2F1/p73 apoptotic pathway. hSirT1 represses E2F1-dependent P1p73 promoter activity in untreated cells and inhibits its activation in response to DNA damage. hSirT1, PCAF, and E2F1 are corecruited in vivo on theP1p73 promoter. hSirT1 deacetylates PCAF in vitro and modulates PCAF acetylation in vivo. In cells exposed to apoptotic DNA damage, nuclear NAD+ levels decrease and inactivate hSirT1 without altering the hSirT1 interaction with PCAF and hSirT1 binding to the P1p73 promoter. The reactivation of hSirT1 by pyruvate that increases the [NAD+]/[NADH] ratio completely abolished the DNA damage-induced activation of TAp73 expression, thus linking the modulation of chromatin-bound hSirT1 deacetylase activity by the intracellular redox state with P1p73 promoter activity. The release of PCAF from hSirT1 repression favors the assembly of transcriptionally active PCAF/E2F1 complexes onto the P1p73 promoter and p53-independent apoptosis. Our results identify hSirT1 and PCAF as potential targets to modulate tumor cell survival and chemoresistance irrespective of p53 status.
43
Kucheryavykh, Yuriy V., Josue Davila, Jescelica Ortiz-Rivera, Mikhael Inyushin, Luis Almodovar, Miguel Mayol, Moraima Morales-Cruz, et al. "Targeted Delivery of Nanoparticulate Cytochrome C into Glioma Cells Through the Proton-Coupled Folate Transporter." Biomolecules 9, no. 4 (April 18, 2019): 154. http://dx.doi.org/10.3390/biom9040154.
Full textAbstract:
In this study, we identified the proton-coupled folate transporter (PCFT) as a route for targeted delivery of drugs to some gliomas. Using the techniques of confocal imaging, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and small interfering (siRNA) knockdown against the PCFT, we demonstrated that Gl261 and A172 glioma cells, but not U87 and primary cultured astrocytes, express the PCFT, which provides selective internalization of folic acid (FA)-conjugated cytochrome c-containing nanoparticles (FA-Cyt c NPs), followed by cell death. The FA-Cyt c NPs (100 µg/mL), had no cytotoxic effects in astrocytes but caused death in glioma cells, according to their level of expression of PCFT. Whole-cell patch clamp recording revealed FA-induced membrane currents in FA-Cyt c NPs-sensitive gliomas, that were reduced by siRNA PCFT knockdown in a similar manner as by application of FA-Cyt c NPs, indicating that the PCFT is a route for internalization of FA-conjugated NPs in these glioma cells. Analysis of human glioblastoma specimens revealed that at least 25% of glioblastomas express elevated level of either PCFT or folate receptor (FOLR1). We conclude that the PCFT provides a mechanism for targeted delivery of drugs to some gliomas as a starting point for the development of efficient methods for treating gliomas with high expression of PCFT and/or FOLR1.
44
Nassar, Antonio Paulo, Beatriz Nicolau Nassif, Daniel Vitório Veiga dos Santos, and Pedro Caruso. "Procalcitonin Clearance at 24, 48, 72, and 96 Hours and Mortality in Patients With Cancer and Sepsis: A Retrospective Cohort Study." Journal of Intensive Care Medicine 35, no. 11 (July 8, 2019): 1297–301. http://dx.doi.org/10.1177/0885066619861588.
Full textAbstract:
Introduction: Previous studies have evaluated procalcitonin clearance (PCTc) as a marker of sepsis severity but at different time points and cutoffs. We aimed to assess the predictive performance of PCTc at different time points of sepsis management in patients with cancer. Methods: This retrospective cohort study included patients with cancer admitted to an intensive care unit between 2013 and 2016. We calculated PCTc at 24, 48, 72, and 96 hours after admission. Its predictive performance for hospital and 90-day mortality was analyzed with receiver operating characteristic curves and areas under the curves (AUCs). Sensitivity and specificity were calculated for different time points using different cutoffs. Results: We included 301 patients. Areas under the curves ranged from 0.62 for PCTc at 24 hours to 0.68 for PCTc at 72 and 96 hours for hospital mortality prediction, and from 0.61 for PCTc at 24 hours to 0.68 for PCTc at 72 hours for 90-day mortality prediction. For hospital mortality prediction, PCTc at 72 hours ≤80% showed the best sensitivity (96.0%; 95% confidence interval [CI]: 90.8%-98.7%), and PCTc at 96 hours ≤50% showed the best specificity (70.7%; 95% CI: 54.5%-83.9%). Conclusions: Procalcitonin clearance at 24, 48, 72, and 96 hours poorly predicted hospital and 90-day mortality. Therefore, daily PCT measurement should not be used to predict mortality for patients with cancer and sepsis.
45
Bigaeva, Emilia, Emilia Gore, Eric Simon, Matthias Zwick, Anouk Oldenburger, Koert P. de Jong, Hendrik S. Hofker, et al. "Transcriptomic characterization of culture-associated changes in murine and human precision-cut tissue slices." Archives of Toxicology 93, no. 12 (November 21, 2019): 3549–83. http://dx.doi.org/10.1007/s00204-019-02611-6.
Full textAbstract:
AbstractOur knowledge of complex pathological mechanisms underlying organ fibrosis is predominantly derived from animal studies. However, relevance of animal models for human disease is limited; therefore, an ex vivo model of human precision-cut tissue slices (PCTS) might become an indispensable tool in fibrosis research and drug development by bridging the animal–human translational gap. This study, presented as two parts, provides comprehensive characterization of the dynamic transcriptional changes in PCTS during culture by RNA sequencing. Part I investigates the differences in culture-induced responses in murine and human PCTS derived from healthy liver, kidney and gut. Part II delineates the molecular processes in cultured human PCTS generated from diseased liver, kidney and ileum. We demonstrated that culture was associated with extensive transcriptional changes and impacted PCTS in a universal way across the organs and two species by triggering an inflammatory response and fibrosis-related extracellular matrix (ECM) remodelling. All PCTS shared mRNA upregulation of IL-11 and ECM-degrading enzymes MMP3 and MMP10. Slice preparation and culturing activated numerous pathways across all PCTS, especially those involved in inflammation (IL-6, IL-8 and HMGB1 signalling) and tissue remodelling (osteoarthritis pathway and integrin signalling). Despite the converging effects of culture, PCTS display species-, organ- and pathology-specific differences in the regulation of genes and canonical pathways. The underlying pathology in human diseased PCTS endures and influences biological processes like cytokine release. Our study reinforces the use of PCTS as an ex vivo fibrosis model and supports future studies towards its validation as a preclinical tool for drug development.
46
Xun, Luying, Sara M. Belchik, Randy Xun, Yan Huang, Huina Zhou, Emiliano Sanchez, ChulHee Kang, and Philip G. Board. "S-Glutathionyl-(chloro)hydroquinone reductases: a novel class of glutathione transferases." Biochemical Journal 428, no. 3 (May 27, 2010): 419–27. http://dx.doi.org/10.1042/bj20091863.
Full textAbstract:
Sphingobium chlorophenolicum completely mineralizes PCP (pentachlorophenol). Two GSTs (glutathione transferases), PcpC and PcpF, are involved in the degradation. PcpC uses GSH to reduce TeCH (tetrachloro-p-hydroquinone) to TriCH (trichloro-p-hydroquinone) and then to DiCH (dichloro-p-hydroquinone) during PCP degradation. However, oxidatively damaged PcpC produces GS-TriCH (S-glutathionyl-TriCH) and GS-DiCH (S-glutathionyl-TriCH) conjugates. PcpF converts the conjugates into TriCH and DiCH, re-entering the degradation pathway. PcpF was further characterized in the present study. It catalysed GSH-dependent reduction of GS-TriCH via a Ping Pong mechanism. First, PcpF reacted with GS-TriCH to release TriCH and formed disulfide bond between its Cys53 residue and the GS moiety. Then, a GSH came in to regenerate PcpF and release GS–SG. A TBLASTN search revealed that PcpF homologues were widely distributed in bacteria, halobacteria (archaea), fungi and plants, and they belonged to ECM4 (extracellular mutant 4) group COG0435 in the conserved domain database. Phylogenetic analysis grouped PcpF and homologues into a distinct group, separated from Omega class GSTs. The two groups shared conserved amino acid residues, for GSH binding, but had different residues for the binding of the second substrate. Several recombinant PcpF homologues and two human Omega class GSTs were produced in Escherichia coli and purified. They had zero or low activities for transferring GSH to standard substrates, but all had reasonable activities for GSH-dependent reduction of disulfide bond (thiol transfer), dehydroascorbate and dimethylarsinate. All the tested PcpF homologues reduced GS-TriCH, but the two Omega class GSTs did not. Thus PcpF homologues were tentatively named S-glutathionyl-(chloro)hydroquinone reductases for catalysing the GSH-dependent reduction of GS-TriCH.
47
Lasry, Inbal, Bluma Berman, Rachel Straussberg, Yael Sofer, Hanna Bessler, Mohamad Sharkia, Fabian Glaser, Gerrit Jansen, Stavit Drori, and Yehuda G. Assaraf. "A novel loss-of-function mutation in the proton-coupled folate transporter from a patient with hereditary folate malabsorption reveals that Arg 113 is crucial for function." Blood 112, no. 5 (September 1, 2008): 2055–61. http://dx.doi.org/10.1182/blood-2008-04-150276.
Full textAbstract:
Abstract Hereditary folate malabsorption (HFM) patients harbor inactivating mutations including R113S in the proton-coupled folate transporter (PCFT), an intestinal folate transporter with optimal activity at acidic pH. Here we identified and characterized a novel R113C mutation residing in the highly conserved first intracellular loop of PCFT. Stable transfectants overexpressing a Myc-tagged wild-type (WT) and mutant R113C PCFT displayed similar transporter targeting to the plasma membrane. However, whereas WT PCFT transfectants showed a 22-fold increase in [3H]folic acid influx at pH 5.5, R113C or mock transfectants showed no increase. Moreover, WT PCFT transfectants displayed a 50% folic acid growth requirement concentration of 7 nM, whereas mock and R113C transfectants revealed 24- to 27-fold higher values. Consistently, upon fluorescein-methotrexate labeling, WT PCFT transfectants displayed a 50% methotrexate displacement concentration of 50 nM, whereas mock and R113C transfectants exhibited 12- to 14-fold higher values. Based on the crystal structure of the homologous Escherichia coli glycerol-3-phosphate transporter, we propose that the cationic R113 residue of PCFT is embedded in a hydrophobic pocket formed by several transmembrane helices that may be part of a folate translocation pore. These findings establish a novel loss of function mutation in HFM residing in an intracellular loop of PCFT crucial for folate transport.
48
Ge, Xinjian, Qihuang Jin, Fang Zhang, Tingting Yan, and Qiwei Zhai. "PCAF Acetylates β-Catenin and Improves Its Stability." Molecular Biology of the Cell 20, no. 1 (January 2009): 419–27. http://dx.doi.org/10.1091/mbc.e08-08-0792.
Full textAbstract:
β-Catenin plays an important role in development and tumorigenesis. However, the effect of a key acetyltransferase p300/CBP-associated factor (PCAF) on β-catenin signaling is largely unknown. In this study, we found PCAF could increase the β-catenin transcriptional activity, induce its nuclear translocation, and up-regulate its protein level by inhibiting its ubiquitination and improving its stability. Further studies showed that PCAF directly binds to and acetylates β-catenin. The key ubiquitination sites Lys-19 and Lys-49 of β-catenin were shown as the critical residues for PCAF-induced acetylation and stabilization. Knockdown of PCAF in colon cancer cells markedly reduced the protein level, transcriptional activity, and acetylation level of β-catenin; promoted cell differentiation; inhibited cell migration; and repressed xenografted tumorigenesis and tumor growth in nude mice. All these data demonstrate that PCAF acetylates β-catenin and regulates its stability, and they raise the prospect that therapies targeting PCAF may be of clinical use in β-catenin–driven diseases, such as colon cancer.
49
Songdej, Natthapol, Guangfen Mao, Lawrence E. Goldfinger, and Angara Koneti Rao. "Transcription Factor RUNX1 Regulates Pctp (Phosphatidylcholine Transfer Protein) in Platelets: A Potential Role in Regulating Platelet Function." Blood 126, no. 23 (December 3, 2015): 2247. http://dx.doi.org/10.1182/blood.v126.23.2247.2247.
Full textAbstract:
Abstract Transcription factor (TF) mutations are increasingly recognized to play a major role in inherited platelet abnormalities. RUNX1, a critical hematopoietic TF, acts in a combinatorial manner with other TFs to regulate numerous megakaryocyte (MK)/platelet genes. Human RUNX1 haplodeficiency is associated with thrombocytopenia, numerous platelet function defects, and increased leukemia risk. We have previously described a patient with a heterozygous RUNX1 nonsense mutation in the conserved runt domain necessary for DNA binding (Sun et al Blood 2004;103;948-54). The patient's platelet abnormalities included impaired aggregation and secretion in response to multiple agonists, granule deficiency, and decreased phosphorylation of myosin light chain and pleckstrin, activation of GPIIb-IIIa, 12-HETE production, and platelet protein kinase C-θ. Transcript expression profiling of patient platelets (Sun et al, J Thromb Haemost 2007;5:146-54) showed numerous genes were significantly downregulated, including myosin light chain (MYL9), platelet factor 4 (PF4), protein kinase C-θ (PRCKQ), and 12-lipoxygenase (ALOX12); these have been shown by us to be regulated by RUNX1. The profiling data also showed 10-fold downregulation of phosphatidylcholine transfer protein (PCTP) gene (fold change ratio 0.09, p=0.02) in the patient compared with normal controls. PCTP is a member of the START (Steroidogenic Acute Regulatory Protein-Related Transfer) domain superfamily and is responsible for the intermembrane transfer of phosphatidylcholine (PC), a major plasma membrane phospholipid. Several findings indicate that PCTP is important for platelet function. PC is the main fraction of platelet phospholipids and source of arachidonic acid (AA) upon activation. Release of free AA from PC is the rate-limiting step in thromboxane production. PC is also a substrate for phospholipase D, which yields phosphatidic acid that can generate the second messenger diacylglycerol. Importantly, platelet PCTP has recently been demonstrated to have a major role in the racial differences in platelet responses - increased PCTP expression has been linked to the higher platelet aggregation and calcium mobilization induced by thrombin receptor protease-activated receptor 4 (PAR4) in blacks as compared to whites (Edelstein et al Nat Med 2013;19:1609-16). Little is known regarding the regulation of PCTP in MKs/platelets. Based on the decreased platelet PCTP expression in our patient, we pursued the hypothesis that PCTP is regulated by RUNX1. Corrected total cellular immunofluorescence with anti-PCTP antibody showed significantly reduced platelet PCTP expression by 58% in our patient compared to a normal control. In silico analysis revealed 5 RUNX1 consensus binding sites up to 995 bp of the PCTP 5' upstream region from ATG. To assess for interaction of RUNX1 with the PCTP promoter, chromatin immunoprecipitation (ChIP) assay with anti-RUNX1 antibody was performed using human erythroid leukemia (HEL) cells treated with phorbol 12-myristate 13-acetate (PMA) for 24 hours to induce megakaryocytic transformation. The ChIP studies showed RUNX1 binding to PCTP chromatin in the regions encompassing RUNX1 binding sites 1 (-232/-227) and 2 (-345/-340), at site 3 (-519/-514), and encompassing sites 4 and 5 (-861/-856, -884/-879). Electrophoretic mobility shift assay (EMSA) using PMA-treated HEL cell nuclear extracts showed RUNX1 binding to DNA probes (28-37 bp) containing site 1 (-232/-227) and both sites 4 and 5 (-861/-856, -884/-879). To assess the effect of modulating RUNX1 expression on PCTP expression, PMA-treated HEL cells were transfected with RUNX1 overexpression plasmid or siRNA. PCTP mRNA and protein expression were increased with RUNX1 overexpression and reduced with RUNX1 knockdown, suggesting that PCTP is regulated by RUNX1. Conclusions: Our results provide evidence that PCTP is a direct transcriptional target of and regulated by RUNX1, and a cogent molecular mechanism for downregulation of platelet PCTP in our patient with RUNX1 haplodeficiency. Regulation of PCTP by RUNX1 may be relevant to the platelet dysfunction in RUNX1 haplodeficiency as well as to racial differences in platelet responses linked to the differential platelet expression of PCTP. Disclosures No relevant conflicts of interest to declare.
50
Elovaara, I., S. Koenig, A. Y. Brewah, R. M. Woods, T. Lehky, and S. Jacobson. "High human T cell lymphotropic virus type 1 (HTLV-1)-specific precursor cytotoxic T lymphocyte frequencies in patients with HTLV-1-associated neurological disease." Journal of Experimental Medicine 177, no. 6 (June 1, 1993): 1567–73. http://dx.doi.org/10.1084/jem.177.6.1567.
Full textAbstract:
The frequencies of human T cell lymphotropic virus type 1 (HTLV-1)-specific CD8+ precursor cytotoxic T lymphocytes (pCTL) were quantitated from lymphocytes obtained from the peripheral blood and cerebrospinal fluid (CSF) of infected individuals with and without HTLV-1-associated neurological disease. An estimate of the pCTL was obtained by separating CD8+ cells, plating these cells in limiting dilution, and testing wells for HTLV-1 specific lysis. Targets consisted of autologous lymphoblastoid cell lines (LCL) infected with vaccinia constructs expressing HTLV-1 gene products or LCL pulsed with HTLV-1 synthetic peptides. In patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), the frequency of HTLV-1 p40X-specific pCTL was at least 40-280-fold higher than in asymptomatic HTLV-1-infected individuals. All HAM/TSP patients (five of five) predominantly recognized HTLV-1 products encoded within the pX region. Lower pCTL to env were demonstrated in three patients, and only one of five HAM/TSP patients had pCTL to gag. A synthetic peptide corresponding to the tax region of HTLV-1 (peptide 11-19, amino acid sequence LLFGYPVYV) was recognized in association with human histocompatibility leukocyte antigen (HLA)-A2 in two HLA-A2 HAM/TSP patients with a high CD8+ pCTL frequency of 1/325 and 1/265, respectively. A second immunodominant region of HTLV-1 tax (peptide 90-55, amino acid sequence VPYKRIEEL) was identified to be restricted by HLA-B14 in two HLA-B14 HAM/TSP patients with a CD8+ pCTL frequency of 1/640 and 1/1,125, respectively. Lymphocytes from the CSF of a patient with HAM/TSP also showed a pCTL frequency against p40X of similar magnitude to that demonstrated from peripheral blood lymphocytes (PBL). The HLA-A2-mediated CSF pCTL activity to the immunodominant tax-specific peptide 11-19 was also comparable to pCTL from PBL. These results indicate that an extremely high pCTL frequency to HTLV-1 tax-encoded peptides may be related to pathogenesis of myeloneuropathy associated with HTLV-1.