Case Studies in Teaching

This chapter will:; ; ; Present a final set of three teaching case studies to illustrate the points that we have made throughout this volume;; ; ; Discuss extensive tasks designed for business students to enable them to practise and develop the skills of negotiating, relationship-building, decision-making, and problem-solving, as these are used by business professionals;; ; ; Conclude with recommendations for further readings based on research into spoken and written business discourse

Engineering micro-alignments of 2- and 3-D hESC-derived ventricular tissues to reproduce anisotropic properties of the native heart: an accurate arrhythmias model for cardiotoxicity screening

DMM 2011 entitled: Re-engineering Regenerative MedicinePoster Session - Heart Regeneration: no. 26In the native heart, ventricular CMs are aligned in a highly organized structured manner such that the conduction of electrical signals is anisotropic for directional and coordinated contractions to effectively pump blood. In other words, electrical conduction is asymmetrical (i.e. anisotropy) with distinct transverse and longitudinal velocities. Unlike the native ventricle, clusters of hESC-CMs differentiated using either the EB formation or directed differentiation are random structures with NO obvious organization and anisotropy as we previously published. Using a microgroove technology, here we engineered organized 2- and 3-D hESC-derived ventricular strips, followed by high-resolution optical mapping recordings …postprin

The Escherichia coli transcriptome mostly consists of independently regulated modules

Underlying cellular responses is a transcriptional regulatory network (TRN) that modulates gene expression. A useful description of the TRN would decompose the transcriptome into targeted effects of individual transcriptional regulators. Here, we apply unsupervised machine learning to a diverse compendium of over 250 high-quality Escherichia coli RNA-seq datasets to identify 92 statistically independent signals that modulate the expression of specific gene sets. We show that 61 of these transcriptomic signals represent the effects of currently characterized transcriptional regulators. Condition-specific activation of signals is validated by exposure of E. coli to new environmental conditions. The resulting decomposition of the transcriptome provides: a mechanistic, systems-level, network-based explanation of responses to environmental and genetic perturbations; a guide to gene and regulator function discovery; and a basis for characterizing transcriptomic differences in multiple strains. Taken together, our results show that signal summation describes the composition of a model prokaryotic transcriptome

The neck-region polymorphism of DC-SIGNR in peri-centenarian from Han Chinese Population

<p>Abstract</p> <p>Background</p> <p>DC-SIGNR (also called CD209L) has been extensively studied on its role in host genetic predisposition to viral infection. In particular, variable number tandem repeat (VNTR) of the neck-region of DC-SIGNR is highly polymorphic and the polymorphism has been investigated for genetic predisposition to various infectious diseases, though conflicting results had been reported. As infection is a major cause of human death and a mechanism of natural selection, we hypothesized that VNTR polymorphism of DC-SIGNR might have an effect on human life span.</p> <p>Methods</p> <p>Here we collected 361 peri-centenarian individuals (age ≥94 for female and age ≥90 for male) and 342 geographically matched controls (age 22-53, mean 35.0 ± 12.0) from Han Chinese. The VNTR polymorphism of the neck region was determined by PCR and genotype was called by separating the PCR products in agarose gel.</p> <p>Results</p> <p>A total of 11 genotypes and 5 alleles were found in our population. The genotype distribution, allele frequencies and homozygote proportion did not show a significant difference between peri-centenarian and control group. As gender differences in lifespan are ubiquitously observed throughout the animal kingdom, we then stratified the samples by gender. There was more 6/7 genotypes in female peri-centenarian group than that in female control group, at a marginal level of significance (5.56 vs. 1.28%, p = 0.041). The difference was not significant after correction by Bonferroni method. It suggests a possible differential effect of DC-SIGNR VNTR genotypes between sexes. Further studies are warranted to confirm our preliminary findings and investigate the mechanisms of the underlying functions.</p> <p>Conclusions</p> <p>Our study indicated that there was absence of association between the neck region polymorphism of DC-SIGNR and longevity in Han Chinese population. But the question of whether the DC-SIGNR could affect longevity in a gender-specific pattern remains open.</p

Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men

Purpose: The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises. Methods: Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (W) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography. Results: Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W (13.21° ± 4.63° to 20.04° ± 4.76°, p  0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s to 75% MVC 124.32° ± 34.89° s, p  0.05) then increased from 40 to 75% MVC [−98.44 (43.54)° s to −138.42 (73.29)° s, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01). Conclusion: Cycling increased LV twist to 30% W which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise

Common Variants at 10 Genomic Loci Influence Hemoglobin A(1C) Levels via Glycemic and Nonglycemic Pathways

OBJECTIVE Glycated hemoglobin (HbA1c), used to monitor and diagnose diabetes, is influenced by average glycemia over a 2- to 3-month period. Genetic factors affecting expression, turnover, and abnormal glycation of hemoglobin could also be associated with increased levels of HbA1c. We aimed to identify such genetic factors and investigate the extent to which they influence diabetes classification based on HbA1c levels. RESEARCH DESIGN AND METHODS We studied associations with HbA1c in up to 46,368 nondiabetic adults of European descent from 23 genome-wide association studies (GWAS) and 8 cohorts with de novo genotyped single nucleotide polymorphisms (SNPs). We combined studies using inverse-variance meta-analysis and tested mediation by glycemia using conditional analyses. We estimated the global effect of HbA1c loci using a multilocus risk score, and used net reclassification to estimate genetic effects on diabetes screening. RESULTS Ten loci reached genome-wide significant association with HbA1c, including six new loci near FN3K (lead SNP/P value, rs1046896/P = 1.6 × 10−26), HFE (rs1800562/P = 2.6 × 10−20), TMPRSS6 (rs855791/P = 2.7 × 10−14), ANK1 (rs4737009/P = 6.1 × 10−12), SPTA1 (rs2779116/P = 2.8 × 10−9) and ATP11A/TUBGCP3 (rs7998202/P = 5.2 × 10−9), and four known HbA1c loci: HK1 (rs16926246/P = 3.1 × 10−54), MTNR1B (rs1387153/P = 4.0 × 10−11), GCK (rs1799884/P = 1.5 × 10−20) and G6PC2/ABCB11 (rs552976/P = 8.2 × 10−18). We show that associations with HbA1c are partly a function of hyperglycemia associated with 3 of the 10 loci (GCK, G6PC2 and MTNR1B). The seven nonglycemic loci accounted for a 0.19 (% HbA1c) difference between the extreme 10% tails of the risk score, and would reclassify ∼2% of a general white population screened for diabetes with HbA1c. CONCLUSIONS GWAS identified 10 genetic loci reproducibly associated with HbA1c. Six are novel and seven map to loci where rarer variants cause hereditary anemias and iron storage disorders. Common variants at these loci likely influence HbA1c levels via erythrocyte biology, and confer a small but detectable reclassification of diabetes diagnosis by HbA1c

Human Skeletal Muscle Possesses an Epigenetic Memory of Hypertrophy

It is unknown if adult human skeletal muscle has an epigenetic memory of earlier encounters with growth. We report, for the first time in humans, genome-wide DNA methylation (850,000 CpGs) and gene expression analysis after muscle hypertrophy (loading), return of muscle mass to baseline (unloading), followed by later hypertrophy (reloading). We discovered increased frequency of hypomethylation across the genome after reloading (18,816 CpGs) versus earlier loading (9,153 CpG sites). We also identified AXIN1, GRIK2, CAMK4, TRAF1 as hypomethylated genes with enhanced expression after loading that maintained their hypomethylated status even during unloading where muscle mass returned to control levels, indicating a memory of these genes methylation signatures following earlier hypertrophy. Further, UBR5, RPL35a, HEG1, PLA2G16, SETD3 displayed hypomethylation and enhanced gene expression following loading, and demonstrated the largest increases in hypomethylation, gene expression and muscle mass after later reloading, indicating an epigenetic memory in these genes. Finally, genes; GRIK2, TRAF1, BICC1, STAG1 were epigenetically sensitive to acute exercise demonstrating hypomethylation after a single bout of resistance exercise that was maintained 22 weeks later with the largest increase in gene expression and muscle mass after reloading. Overall, we identify an important epigenetic role for a number of largely unstudied genes in muscle hypertrophy/memory