Comparison of teaching the basic electrocardiographic concept of frontal plane QRS axis using the classical versus the orderly electrocardiogram limb lead displays

This study compares the effectiveness of teaching the calculation of frontal plane QRS axis with the use of the classical versus the orderly electrocardiographic limb lead display. Eighty-three students from two environments were randomized into two groups and were taught to determine frontal plane axis with one of the methods. The accuracy and time to determine the axis were tested on 10 electrocardiograms. In the United States the group using the classical display achieved 4.2 (+/-2.7) correct answers, whereas those using the orderly method achieved 6.8 (+/-3.0) (p = 0.0006). The classical group used 9.2 (+/-2.8) minutes to complete the test, whereas the orderly group needed 7.2 (+/-2.0) minutes (p = 0.015). The results achieved in Sweden were similar. The use of the orderly electrocardiographic limb lead display results in greater diagnostic accuracy in less time than the classical display when determining the frontal plane QRS axis.     

Metabolic consequences of phosphotransferase (PTS) mutation in a phenylalanine-producing recombinant Escherichia coli

E. coli strain PPA305, which has a wild-type PTS system, and PPA316, which utilizes a proton-galactose symport system for glucose uptake, were used as host strains to harbor a phenylalanine overproduction plasmid pSY130-14 and to study the effects of using different glucose uptake systems on phenylalanine production. The non-PTS strain (PPA316/pSY130-14) produced much less phenylalanine, ranging from 0 to 67% of that produced by the PTS strain (PPA305/pSY130-14) depending on cultivation conditions used. The non-PTS strain PPA316/pSY130-14 had an intracellular PEP concentration only one-sixth that of the PTS strain, PPA305/pSY130-14. Additionally, PPA316/pSY130-14 had a substantially lower energy state in terms of the size of the pool of high-energy phosphate compounds and the magnitude of the pH difference across the cytoplasmic membrane. The non-PTS strain consumed oxygen at a higher rate, attained lower biomass concentration, and produced no acetate and phenylalanine during fermentation, suggesting more carbon was oxidized to CO2, most likely through the TCA cycle. Analysis of intracellular fluxes through the central carbon pathways was performed for each strain utilizing exponential phase data on extracellular components and assuming quasi-steady state for intermediate metabolites. The non-PTS strain had a higher flux through pyruvate kinase (PYK) and TCA cycle which, in agreement with the observed higher oxygen uptake rate, suggests that more carbon was oxidized to CO2 through the TCA cycle. Further analysis using rate expression data for PYK and NMR data for the intracellular metabolites identified the regulatory properties of PYK as the probable cause for lower intracellular PEP levels in PPA316/pSY130-14.     

Reliability of adult retrospective recall of lifetime tobacco use.

Retrospective assessment of tobacco use underlies much of the data collected in epidemiological and genetic epidemiological research. Although individuals are asked to report lifetime tobacco use for periods spanning months to decades, the test-retest reliability intervals of the instruments often span only a few weeks to several months. The present analyses examined the test-retest reliability of retrospective tobacco use measures, including details of first use, circumstances of first use, and initial subjective reactions. The questions were part of the Lifetime Tobacco Use Questionnaire (LTUQ), a Web-based questionnaire designed to assess use of most forms of tobacco or nicotine retrospectively across the lifespan. A convenience sample of 236 men and women with history of tobacco use (Time 1 mean age, 44.9 years; 74.2% females; 75.1% regular monthly tobacco use) responded verifiably to invitations to self-administer the LTUQ two times, 2 years apart. Test-retest reliability analyses reflected high reliability for salient tobacco-use questions. Acceptable levels of reliability were observed for initial subjective reactions to smoking, if the scaled response options were dichotomized. Few differences in the reliability of recall were apparent between sexes and between age groups. These results indicate that recall of important tobacco use information can form a reliable basis for research.