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Preschool Children's Understanding of the Graphic Features of Writing
Mortensen, Jennifer,Burnham, Melissa Korean Association of Child Studies 2012 Child studies in Asia-Pacific context Vol.2 No.1
This project examined 2, 3, and 4-year-old children (N = 34) in a university campus child care setting to assess their understanding of the graphic features they use in their emergent writing (to distinguish it from a drawing of the same referent). The graphic features present in samples of the children's work were examined and compared to the graphic features children could identify through verbal and nonverbal communication. We examined the frequencies of graphic feature identification, as well as significant differences between graphic feature usage and graphic feature identification. The most frequently used graphic features were linearity, unidirectionality, and small size of units. The most frequently identified graphic feature was conventional letter. Overall, children used significantly more graphic features than they were able to identify. Significant relationships comparing the 2-year-old group and 4-year-old group's usage and identification were also found. The findings are discussed in terms of their application to early childhood classrooms. Teachers can apply these findings when engaging children in conversations about their emergent writing; these discussions are explored as a beneficial teaching tool.
Preschool Children`s Understanding of the Graphic Features of Writing
Jennifer Mortensen,Melissa Burnham 한국아동학회 2012 Child studies in Asia-Pacific context Vol.2 No.1
This project examined 2, 3, and 4-year-old children (N=34) in a university campus child care setting to assess their understanding of the graphic features they use in their emergent writing (to distinguish it from a drawing of the same referent). The graphic features present in samples of the children`s work were examined and compared to the graphic features children could identify through verbal and nonverbal communication. We examined the frequencies of graphic feature identification, as well as significant differences between graphic feature usage and graphic feature identification. The most frequently used graphic features were linearity, unidirectionality, and small size of units. The most frequently identified graphic feature was conventional letter. Overall, children used significantly more graphic features than they were able to identify. Significant relationships comparing the 2-year-old group and 4-year-old group`s usage and identification were also found. The findings are discussed in terms of their application to early childhood classrooms. Teachers can apply these findings when engaging children in conversations about their emergent writing; these discussions are explored as a beneficial teaching tool.
A class of rigid linker-bearing glucosides for membrane protein structural study
Sadaf, A.,Mortensen, J.,Capaldi, S.,Tikhonova, E.,Hariharan, P.,Ribeiro, O.,Loland, C.,Guan, L.,Byrne, B.,Chae, P. THE ROYAL SOCIETY OF CHEMISTRY 2016 Chemical Science Vol.7 No.3
<P>Membrane proteins are amphipathic bio-macromolecules incompatible with the polar environments of aqueous media. Conventional detergents encapsulate the hydrophobic surfaces of membrane proteins allowing them to exist in aqueous solution. Membrane proteins stabilized by detergent micelles are used for structural and functional analysis. Despite the availability of a large number of detergents, only a few agents are sufficiently effective at maintaining the integrity of membrane proteins to allow successful crystallization. In the present study, we describe a novel class of synthetic amphiphiles with a branched tail group and a triglucoside head group. These head and tail groups were connected via an amide or ether linkage by using a tris(hydroxylmethyl) aminomethane (TRIS) or neopentyl glycol (NPG) linker to produce TRIS-derived triglucosides (TDTs) and NPG-derived triglucosides (NDTs), respectively. Members of this class conferred enhanced stability on target membrane proteins compared to conventional detergents. Because of straightforward synthesis of the novel agents and their favourable effects on a range of membrane proteins, these agents should be of wide applicability to membrane protein science.</P>
Tandem neopentyl glycol maltosides (TNMs) for membrane protein stabilisation
Bae, Hyoung Eun,Mortensen, Jonas S.,Ribeiro, Orquidea,Du, Yang,Ehsan, Muhammad,Kobilka, Brian K.,Loland, Claus J.,Byrne, Bernadette,Chae, Pil Seok The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.81
<P>A novel class of detergents, designated tandem neopentyl glycol maltosides (TNMs), were evaluated with four target membrane proteins. The best detergent varied depending on the target, but TNM-C12L and TNM-C11S were notable for their ability to confer increased membrane protein stability compared to DDM. These agents have potential for use in membrane protein research.</P>
Das, M.,Du, Y.,Mortensen, J.,Ribeiro, O.,Hariharan, P.,Guan, L.,Loland, C.,Kobilka, B.,Byrne, B.,Chae, P. THE ROYAL SOCIETY OF CHEMISTRY 2017 Chemical Science Vol.8 No.2
<P>Amphiphile selection is a crucial step in membrane protein structural and functional study. As conventional detergents have limited scope and utility, novel agents with enhanced efficacy need to be developed. Although a large number of novel agents have been reported, so far there has been no systematically designed comparative study of the protein stabilization efficacy of stereo-isomeric amphiphiles. Here we designed and prepared a novel class of stereo-isomeric amphiphiles, designated butane-1,2,3,4-tetraolbased maltosides (BTMs). These stereoisomers showed markedly different behaviour for most of the targeted membrane proteins depending on the chirality of the linker region. These findings indicate an important role for detergent stereochemistry in membrane protein stabilization. In addition, we generally observed enhanced detergent efficacy with increasing alkyl chain length, reinforcing the importance of the balance between hydrophobicity and hydrophilicity in detergent design. The stereo-isomeric difference in detergent efficacy observed provides an important design principle for the development of novel amphiphiles for membrane protein manipulation.</P>
Sundstrup, Emil,Hansen, Ase M.,Mortensen, Erik L.,Poulsen, Otto M.,Clausen, Thomas,Rugulies, Reiner,Moller, Anne,Andersen, Lars L. Occupational Safety and Health Research Institute 2020 Safety and health at work Vol.11 No.3
Background: The study aimed to determine the association of individual cognitive ability in late midlife with labor market participation among older workers. Methods: This prospective cohort study estimates the risk of long-term sickness absence, disability pension, early retirement, and unemployment from scores on the Intelligenz-Struktur-Test 2000R by combining data from 5076 workers from the Copenhagen Aging and Midlife Biobank with a register on social transfer payments. Analyses were stepwise adjusted for age, gender, physical and psychosocial work environment, health behaviors, occupational social class, education, and chronic diseases. Results: In the fully adjusted model, low cognitive ability (≥1 standard deviation below the mean for each gender) and high cognitive ability (≥1 standard deviation above the mean for each gender) were not associated with risk of any of the four labor market outcomes. Conclusion: Individual cognitive ability in late midlife was not associated with risk of long-term sickness absence, disability pension, early retirement, and unemployment in the fully adjusted model. Thus, no direct effect of individual cognitive ability in late midlife was observed on the risk of permanently or temporarily leaving the labor market.
Bae, Hyoung Eun,Du, Yang,Hariharan, Parameswaran,Mortensen, Jonas S.,Kumar, Kaavya K.,Ha, Betty,Das, Manabendra,Lee, Hyun Sung,Loland, Claus J.,Guan, Lan,Kobilka, Brian K.,Chae, Pil Seok Royal Society of Chemistry 2019 Chemical Science Vol.10 No.4
<▼1><P>An asymmetric MNG, MNG-8,12, provided enhanced stability to human G protein-coupled receptors (GPCRs) compared to the symmetric MNG, MNG-3.</P></▼1><▼2><P>Maintaining protein stability in an aqueous solution is a prerequisite for protein structural and functional studies, but conventional detergents have increasingly showed limited ability to maintain protein integrity. A representative novel agent, maltose neopentyl glycol-3 (MNG-3), has recently substantially contributed to membrane protein structural studies. Motivated by the popular use of this novel agent, we prepared asymmetric versions of MNG-3 and evaluated these agents with several membrane proteins including two G protein-coupled receptors in this study. We found that some new MNGs were significantly more effective than MNG-3 at preserving protein integrity in the long term, suggesting that these asymmetric MNGs will find a wide use in membrane protein studies. In addition, this is the first study addressing the favorable effect of detergent asymmetric nature on membrane protein stability.</P></▼2>
Dendronic trimaltoside amphiphiles (DTMs) for membrane protein study
Sadaf, Aiman,Du, Yang,Santillan, Claudia,Mortensen, Jonas S.,Molist, Iago,Seven, Alpay B.,Hariharan, Parameswaran,Skiniotis, Georgios,Loland, Claus J.,Kobilka, Brian K.,Guan, Lan,Byrne, Bernadette,Cha Royal Society of Chemistry 2017 Chemical Science Vol.8 No.12
<▼1><P>A novel amphiphile with a dendronic hydrophobic group (DTM-A6) was markedly effective at stabilizing and visualizing a GPCR-G<SUB>s</SUB> complex.</P></▼1><▼2><P>The critical contribution of membrane proteins in normal cellular function makes their detailed structure and functional analysis essential. Detergents, amphipathic agents with the ability to maintain membrane proteins in a soluble state in aqueous solution, have key roles in membrane protein manipulation. Structural and functional stability is a prerequisite for biophysical characterization. However, many conventional detergents are limited in their ability to stabilize membrane proteins, making development of novel detergents for membrane protein manipulation an important research area. The architecture of a detergent hydrophobic group, that directly interacts with the hydrophobic segment of membrane proteins, is a key factor in dictating their efficacy for both membrane protein solubilization and stabilization. In the current study, we developed two sets of maltoside-based detergents with four alkyl chains by introducing dendronic hydrophobic groups connected to a trimaltoside head group, designated dendronic trimaltosides (DTMs). Representative DTMs conferred enhanced stabilization to multiple membrane proteins compared to the benchmark conventional detergent, DDM. One DTM (<I>i.e.</I>, DTM-A6) clearly outperformed DDM in stabilizing human β<SUB>2</SUB> adrenergic receptor (β<SUB>2</SUB>AR) and its complex with G<SUB>s</SUB> protein. A further evaluation of this DTM led to a clear visualization of β<SUB>2</SUB>AR-G<SUB>s</SUB> complex <I>via</I> electron microscopic analysis. Thus, the current study not only provides novel detergent tools useful for membrane protein study, but also suggests that the dendronic architecture has a role in governing detergent efficacy for membrane protein stabilization.</P></▼2>
A comparative study of branched and linear mannitol-based amphiphiles on membrane protein stability
Hussain, Hazrat,Helton, Tyler,Du, Yang,Mortensen, Jonas S.,Hariharan, Parameswaran,Ehsan, Muhammad,Byrne, Bernadette,Loland, Claus J.,Kobilka, Brian K.,Guan, Lan,Chae, Pil Seok The Royal Society of Chemistry 2018 The Analyst Vol.143 No.23
<P>The study of membrane proteins is extremely challenging, mainly because of the incompatibility of the hydrophobic surfaces of membrane proteins with an aqueous medium. Detergents are essential agents used to maintain membrane protein stability in non-native environments. However, conventional detergents fail to stabilize the native structures of many membrane proteins. Development of new amphipathic agents with enhanced efficacy for membrane protein stabilization is necessary to address this important problem. We have designed and synthesized linear and branched mannitol-based amphiphiles (MNAs), and comparative studies showed that most of the branched MNAs had advantages over the linear agents in terms of membrane protein stability. In addition, a couple of the new MNAs displayed favorable behaviors compared to <I>n</I>-dodecyl-β-d-maltoside and the previously developed MNAs in maintaining the native protein structures, indicating potential utility of these new agents in membrane protein study.</P>