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Purpose: To confirm that CrCEST in muscle exhibits a slow‐exchanging process, and to obtain high‐resolution amide, creatine (Cr), and phosphocreatine (PCr) maps of skeletal muscle using a POlynomial and Lorentzian Line‐shape Fitting (PLOF) CEST at 3T. Methods: We used dynamic changes in PCr/CrCEST of mouse hindlimb before and after euthanasia to assign the Cr and PCr CEST peaks in the Z‐spectrum at 3T and to obtain the optimum saturation parameters. Segmented 3D EPI was employed to obtain multi‐slice amide, PCr, and Cr CEST maps of human skeletal muscle. Subsequently, the PCrCEST maps were calibrated using the PCr concentrations determined by 31P MRS. Results: A comparison of the Z‐spectra in mouse hindlimb before and after euthanasia indicated that CrCEST is a slow‐exchanging process in muscle (<150.7 s−1). This allowed us to simultaneously extract PCr/CrCEST signals at 3T using the PLOF method. We determined optimal B1 values ranging from 0.3 to 0.6 μT for CrCEST in muscle and 0.3–1.2 μT for PCrCEST. For the study on human calf muscle, we determined an optimum saturation time of 2 s for both PCr/CrCEST (B1 = 0.6 μT). The PCr/CrCEST using 3D EPI were found to be comparable to those obtained using turbo spin echo (TSE). (3D EPI/TSE PCr: (2.6 ± 0.3) %/(2.3 ± 0.1) %; Cr: (1.3 ± 0.1) %/(1.4 ± 0.07) %). Conclusions: Our study showed that in vivo CrCEST is a slow‐exchanging process. Hence, amide, Cr, and PCr CEST in the skeletal muscle can be mapped simultaneously at 3T by PLOF CEST. [ABSTRACT FROM AUTHOR]

Purpose: To assess the feasibility of CEST‐based creatine (Cr) mapping in brain at 3T using the guanidino (Guan) proton resonance. Methods: Wild type and knockout mice with guanidinoacetate N‐methyltransferase deficiency and low Cr and phosphocreatine (PCr) concentrations in the brain were used to assign the Cr and protein‐based arginine contributions to the GuanCEST signal at 2.0 ppm. To quantify the Cr proton exchange rate, two‐step Bloch–McConnell fitting was used to fit the extracted CrCEST line‐shape and multi‐B1 Z‐spectral data. The pH response of GuanCEST was simulated to demonstrate its potential for pH mapping. Results: Brain Z‐spectra of wild type and guanidinoacetate N‐methyltransferase deficiency mice show a clear Guan proton peak at 2.0 ppm at 3T. The CrCEST signal contributes ∼23% to the GuanCEST signal at B1 = 0.8 μT, where a maximum CrCEST effect of 0.007 was detected. An exchange rate range of 200–300 s−1 was estimated for the Cr Guan protons. As revealed by the simulation, an elevated GuanCEST in the brain is observed when B1 is less than 0.4 μT at 3T, when intracellular pH reduces by 0.2. Conversely, the GuanCEST decreases when B1 is greater than 0.4 μT with the same pH drop. Conclusions: CrCEST mapping is possible at 3T, which has potential for detecting intracellular pH and Cr concentration in brain. [ABSTRACT FROM AUTHOR]

As part of a 3-wk intersession workshop funded by a National Science Foundation Expeditions in Computing award, 15 undergraduate students from the City University of New York collaborated on a study aimed at characterizing the voltage dynamics and arrhythmogenic behavior of cardiac cells for a broad range of physiologically relevant conditions using an in silico model. The primary goal of the workshop was to cultivate student interest in computational modeling and analysis of complex systems by introducing them through lectures and laboratory activities to current research in cardiac modeling and by engaging them in a hands-on research experience. The success of the workshop lay in the exposure of the students to active researchers and experts in their fields, the use of hands-on activities to communicate important concepts, active engagement of the students in research, and explanations of the significance of results as the students generated them. The workshop content addressed how spiral waves of electrical activity are initiated in the heart and how different parameter values affect the dynamics of these reentrant waves. Spiral waves are clinically associated with tachycardia, when the waves remain stable, and with fibrillation, when the waves exhibit breakup. All in silico experiments were conducted by simulating a mathematical model of cardiac cells on graphics processing units instead of the standard central processing units of desktop computers. This approach decreased the run time for each simulation to almost real time, thereby allowing the students to quickly analyze and characterize the simulated arrhythmias. Results from these simulations, as well as some of the background and methodology taught during the workshop, is presented in this article along with the programming code and the explanations of simulation results in an effort to allow other teachers and students to perform their own demonstrations, simulations, and studies. (Contains 9 figures, 2 tables and 1 footnote.)

Many school psychologists focus their interpretation on composite scores from intelligence test batteries designed to measure the broad abilities from the Cattell-Horn-Carroll theory. The purpose of this study was to investigate the general factor loadings and specificity of the broad ability composite scores from one such intelligence test battery, the Woodcock-Johnson III Tests of Cognitive Abilities Normative Update (Woodcock, McGrew, Schrank, & Mather, 2007). Results from samples beginning at age 4 and continuing through age 60 indicate that Comprehension-Knowledge, Long-Term Retrieval, and Fluid Reasoning appear to be primarily measures of the general factor at many ages. In contrast, Visual-Spatial Thinking, Auditory Processing, and Processing Speed appear to be primarily measures of specific abilities at most ages. We offer suggestions for considering both the general factor and specific abilities when interpreting Cattell-Horn-Carroll broad ability composite scores. (Contains 2 tables and 7 footnotes.)

In soybean, asynaptic and desynaptic mutants lead to abnormal meiosis and fertility reduction. Several male-sterile, female-sterile mutants have been identified and studied in soybean, however, some of these mutants have not been mapped to locations on soybean chromosomes. The objectives of this study were to molecularly map five male-sterile, female-sterile genes (st2, st4, st5, st6, and st7) in soybean and compare the map locations of these genes with already mapped sterility genes. Microsatellite markers were used in bulked segregant analyses to locate all five malesterile, female-sterile genes to soybean chromosomes, and markers from the corresponding chromosomes were used on F2 populations to generate genetic linkage maps. The st2, st4, st5, st6, and st7 genes were located on molecular linkage group (MLG) B1 (chromosome 11), MLG D1a (chromosome 01), MLG F (chromosome 13), MLG B2 (chromosome 14), and D1b (chromosome 02), respectively. The st2, st4, st5, st6, and st7 genes were flanked to 10.3 (~399 kb), 6.3 (~164 kb), 3.9 (~11.8 Mb), 11.0 (~409 kb), and 5.3 cM (~224 kb), and the flanked regions contained 57,17, 362, 52, and 17 predicted genes, respectively. Future characterization of candidate genes should facilitate identification of the male- and female-fertility genes, which may provide vital insights on structure and function of genes involved in the reproductive pathway in soybean. Key words: Glycine max, sterility, simple sequence repeat, genetic linkage map, male-sterile female-sterile. Chez le soya, des mutants asynaptiques et desynaptiques presentent des anomalies meiotiques et une reduction de la fertilite. Plusieurs mutants presentant une sterilite male et femelle ont ete identifies et etudies, mais certains de ceux-ci n'ont pas ete situes sur les chromosomes du soya. Les objectifs de ce travail etaient de realiser la cartographie de cinq genes de sterilite male et femelle (st2, st4, st5, st6 et st7) chez le soya et de comparer la position de ces genes avec celle d'autres genes de sterilite deja positionnes. Des marqueurs microsatellites ont ete employes dans le cadre d'analyses de segregants en melange afin d'assigner une position chromosomique aux cinq genes de sterilite male et femelle. Les marqueurs situes sur ces chromosomes ont ete employes sur des populations F2 afin de generer des cartes genetiques. Les genes st2, st4, st5, st6 et st7 ont ete assignes respectivement aux groupes de liaison moleculaires (MLG) B1 (chromosome 11), MLG D1a (chromosome 01), MLG F (chromosome 13), MLG B2 (chromosome 14) et MLG D1b (chromosome 2). Les genes st2, st4, st5, st6 et st7 ont ete assignes a des intervalles de 10,3 (~399 kb), 6,3 (~164 kb), 3,9 (~11,8 Mb), 11,0 (~409 kb) et 5,3 cM (~224 kb); ces intervalles contenaient respectivement 57,17, 362, 52 et 17 genes predits. Une future caracterisation de genes candidats devrait faciliter l'identification des genes de fertilite male et femelle, laquelle fournira un eclairage important sur la structure et la fonction des genes impliques dans la reproduction chez le soya. [Traduit par la Redaction] Mots-cles: Glycine max, sterilite, sequence simple repetee, carte genetique, sterilite male et femelle., Introduction In soybean, asynaptic and desynaptic mutants lead to abnormal meiosis and fertility reduction. This is caused by abnormal pairing of chromosomes during the first meiotic prophase, also known as [...]