http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Stability of Wake-Sleep Cycles Requires Robust Degradation of the PERIOD Protein
D’Alessandro, Matthew,Beesley, Stephen,Kim, Jae Kyoung,Jones, Zachary,Chen, Rongmin,Wi, Julie,Kyle, Kathleen,Vera, Daniel,Pagano, Michele,Nowakowski, Richard,Lee, Choogon Elsevier 2017 Current biology Vol.27 No.22
<P><B>Summary</B></P> <P>Robustness in biology is the stability of phenotype under diverse genetic and/or environmental perturbations. The circadian clock has remarkable stability of period and phase that—unlike other biological oscillators—is maintained over a wide range of conditions. Here, we show that the high fidelity of the circadian system stems from robust degradation of the clock protein PERIOD. We show that PERIOD degradation is regulated by a balance between ubiquitination and deubiquitination, and that disruption of this balance can destabilize the clock. In mice with a loss-of-function mutation of the E3 ligase gene <I>β-Trcp2</I>, the balance of PERIOD degradation is perturbed and the clock becomes dramatically unstable, presenting a unique behavioral phenotype unlike other circadian mutant animal models. We believe that our data provide a molecular explanation for how circadian phases, such as wake-sleep onset times, can become unstable in humans, and we present a unique mouse model to study human circadian disorders with unstable circadian rhythm phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nonlinear degradation of PER is required for the robustness of circadian rhythms </LI> <LI> PER degradation is regulated by a balance between ubiquitination and deubiquitination </LI> <LI> Disrupting this balance causes irregular wake-sleep cycles in mice </LI> </UL> </P>
Daniel, D. Joseph,Ramasamy, P.,Ramaseshan, R.,Kim, H.J.,Kim, Sunghwan,Bhagavannarayana, G.,Cheon, Jong-Kyu Elsevier 2017 Optical materials Vol.72 No.-
<P><B>Abstract</B></P> <P>Polycrystalline compounds of LiBaF<SUB>3</SUB> were synthesized using conventional solid state reaction route and the phase purity was confirmed using powder X-ray diffraction technique. Using vertical Bridgman technique single crystal was grown from melt. Rocking curve measurements have been carried out to study the structural perfection of the grown crystal. The single peak of diffraction curve clearly reveals that the grown crystal was free from the structural grain boundaries. The low temperature thermoluminescence of the X-ray irradiated sample has been analyzed and found four distinguishable peaks having maximum temperatures at 18, 115, 133 and 216 K. Activation energy (E) and frequency factor (s) for the individual peaks have been studied using Peak shape method and the computerized curve fitting method combining with the T<SUB>max</SUB> <B>-</B> T<SUB>Stop</SUB> procedure. Nanoindentation technique was employed to study the mechanical behaviour of the crystal. The indentation modulus and Vickers hardness of the grown crystal have values of 135.15 GPa and 680.81 respectively, under the maximum indentation load of 10 mN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The LiBaF<SUB>3</SUB> Single crystal was grown from the melt by using the Bridgman technique. </LI> <LI> Structural perfection was monitored by HRXRD analysis. </LI> <LI> Trap centers were analyzed by Low temperature thermoluminescence spectra. </LI> <LI> Kinetic parameters have been studied by using various standard methods. </LI> </UL> </P>
Daniel, D. Joseph,Kim, H.J.,Kim, Sunghwan Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.7
<P><B>Abstract</B></P> <P>Li<SUB>3</SUB>K<SUB>3</SUB>Y<SUB>7</SUB>(BO<SUB>3</SUB>)<SUB>9</SUB> has been synthesized using conventional solid-state reaction techniques. The microstructure and morphology of the synthesized compound were observed with a field-emission scanning electron microscope. The fundamental vibrational modes of borate compounds are determined with Fourier-transform infrared spectroscopy (FT-IR) analysis. The elements present in the sample were confirmed by energy-dispersive X-ray spectroscopy (EDS) analysis. The effective atomic number (Z<SUB>eff</SUB>) for this compound was determined and found to be 32.08. X-ray-induced luminescence spectra shows only one band at 350 nm (3.7 eV) that is related to radiation annihilation of self-trapped excitons. Thermoluminescence (TL) measurements were carried out under a heating rate of 2 K/s, followed by X-ray irradiation. It was observed that the LKYBO compound has one intensive TL peak at 434 K, and two weak intensity peaks at 380 K and 525 K. The TL kinetic parameters, such as trap depth (E) and frequency factor (s<SUP>−1</SUP>), for all three glow peaks were analyzed using various standard methods and are reported for the first time. A mean value of 1.10 eV is obtained for the main peak.</P>
Highly stable trypsin-aggregate coatings on polymer nanofibers for repeated protein digestion
Kim, Byoung Chan,Lopez-Ferrer, Daniel,Lee, Sang-Mok,Ahn, Hye-Kyung,Nair, Sujith,Kim, Seong H.,Kim, Beom Soo,Petritis, Konstantinos,Camp, David G.,Grate, Jay W.,Smith, Richard D.,Koo, Yoon-Mo,Gu, Man B WILEY-VCH Verlag 2009 Proteomics Vol.9 No.7
<P>A stable and robust trypsin-based biocatalytic system was developed and demonstrated for proteomic applications. The system utilizes polymer nanofibers coated with trypsin aggregates for immobilized protease digestions. After covalently attaching an initial layer of trypsin to the polymer nanofibers, highly concentrated trypsin molecules are crosslinked to the layered trypsin by way of a glutaraldehyde treatment. This process produced a 300-fold increase in trypsin activity compared with a conventional method for covalent trypsin immobilization, and proved to be robust in that it still maintained a high level of activity after a year of repeated recycling. This highly stable form of immobilized trypsin was resistant to autolysis, enabling repeated digestions of BSA over 40 days and successful peptide identification by LC-MS/MS. This active and stable form of immobilized trypsin was successfully employed in the digestion of yeast proteome extract with high reproducibility and within shorter time than conventional protein digestion using solution phase trypsin. Finally, the immobilized trypsin was resistant to proteolysis when exposed to other enzymes (i.e., chymotrypsin), which makes it suitable for use in “real-world” proteomic applications. Overall, the biocatalytic nanofibers with trypsin aggregate coatings proved to be an effective approach for repeated and automated protein digestion in proteomic analyses.</P>
Daniel, D. Joseph,Raja, A.,Kim, H.J.,Ramasamy, P. Elsevier 2018 OPTIK -STUTTGART- Vol.158 No.-
<P><B>Abstract</B></P> <P>In this paper, we present an environment friendly hydrothermal process to synthesize nano/sub micro particles of the rare earth activated complex fluoride NaMgF<SUB>3</SUB> at 180 °C. The tittle compound synthesis was carried out at elevated pressure and temperature in an aqueous medium. The powder X-ray diffraction pattern was recorded to check the phase purity of the synthesised compound. Synthesized compounds were micro and nanocrystalline with orthorhombic perovskite crystal structure, space group Pcmn. In order to identify the functional groups Fourier Transform Infrared spectral analysis have been performed. The size and shape of the synthesised compounds were studied by using Field Emission - Scanning Electron Microscope images. Chemical composition of the synthesised compounds were checked by the energy - dispersive X-ray spectra. The absorption bands around 220 and 270 nm were observed which is corresponding to the electronic transition between 4f and 5d configuration of Ce<SUP>3+</SUP>. Photoluminescence emission related to the 5 d → 4 f transitions in Ce<SUP>3+</SUP> was observed at 324 nm. Thermoluminescence properties were studied for the X-ray irradiated samples. The glow curve kinetic parameters of activation energy (E) and frequency factor (S) were calculated using standard methods.</P>
Isaac E. Kim Jr.,Daniel D. Kim,Juliana E. Kim,Elliott Rebello,David Chung,Parker Woolley,Daniel Lee,Brittany A. Borden,Aaron Wang,Douglas Villalta,Agatha Sutherland,Sebastian De Armas,Matthew Liu,Hann 한국의학교육학회 2022 Korean journal of medical education Vol.34 No.2
Purpose: Medical schools have faced various challenges in preparing their clinical students for the frontlines of a pandemic. This study investigated medical students’ satisfaction with their institutions during the coronavirus disease 2019 (COVID-19) pandemic with the intention of guiding educators in future public health crises. Methods: In this cross-sectional study surveying students in clinical rotations, the primary outcome was overall satisfaction regarding medical schools’ responses to the pandemic, and the four secondary outcomes were school communication, exposure to COVID-19, availability of personal protective equipment, and access to COVID-19 testing. Results: The survey was distributed to ten medical schools, of which 430 students responded for a response rate of 13.0%. While most students were satisfied (61.9%, n=266) with their schools’ response, more than one in five (21.9%, n=94) were dissatisfied. Among the four secondary outcomes, communication with students was most predictive of overall satisfaction. Conclusion: In future crises, schools can best improve student satisfaction by prioritizing timely communication.
Nanobiocatalysis for protein digestion in proteomic analysis
Kim, Jungbae,Kim, Byoung Chan,Lopez-Ferrer, Daniel,Petritis, Konstantinos,Smith, Richard D. WILEY-VCH Verlag 2010 Proteomics Vol.10 No.4
<P>The process of protein digestion is a critical step for successful protein identification in bottom-up proteomic analyses. To substitute the present practice of in-solution protein digestion, which is long, tedious, and difficult to automate, many efforts have been dedicated for the development of a rapid, recyclable and automated digestion system. Recent advances of nanobiocatalytic approaches have improved the performance of protein digestion by using various nanomaterials such as nanoporous materials, magnetic nanoparticles, and polymer nanofibers. Especially, the unprecedented success of trypsin stabilization in the form of trypsin-coated nanofibers, showing no activity decrease under repeated uses for 1 year and retaining good resistance to proteolysis, has demonstrated its great potential to be employed in the development of automated, high-throughput, and on-line digestion systems. This review discusses recent developments of nanobiocatalytic approaches for the improved performance of protein digestion in speed, detection sensitivity, recyclability, and trypsin stability. In addition, we also introduce approaches for protein digestion under unconventional energy input for protein denaturation and the development of microfluidic enzyme reactors that can benefit from recent successes of these nanobiocatalytic approaches.</P>