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For a variety of reasons, understanding oxidation-reduction (redox) reactions can be challenging for introductory chemistry students. To provide an experiential foundation for students to learn redox concepts, we developed a laboratory experiment that frames redox reactions as a simulated murder mystery. In this experiment, permanganate, which serves as the oxidizing agent, reacts with each of the four monomer units of deoxyribonucleic acid (DNA), which serve as the reducing agents. The reactions are designed to produce dissimilar manganese oxidation states, and hence dissimilar solution colors. For practical reasons, the four monomer units of DNA are used as mimics of four polymeric DNAs from four murder suspects. The color obtained from the redox reaction using "DNA" from the murder weapon is compared to that from the four suspects to identify the perpetrator. The experiment can contribute to the students' emergent understanding of basic redox concepts, of the variable nature of transition metal oxidation states, and of the concept that the DNA monomers are distinct chemicals with distinct reactivities (i.e., reducing potentials in this experiment). Alternative strategies for framing the experiment, as well as some of its limitations, are discussed. The contributions of first-year undergraduate researchers to this experiment are also described.

BackgroundExtracellular matrix expansion may be a fundamental feature of adverse myocardial remodeling, it appears to be treatable, and its measurement may improve risk stratification. Yet, the relationship between mortality and extracellular matrix is not clear because of difficulties with its measurement. To assess its relationship with outcomes, we used novel, validated cardiovascular magnetic resonance techniques to quantify the full spectrum of extracellular matrix expansion not readily detectable by conventional cardiovascular magnetic resonance.Methods and resultsWe recruited 793 consecutive patients at the time of cardiovascular magnetic resonance without amyloidosis or hypertrophic cardiomyopathy as well as 9 healthy volunteers (ages 20-50 years). We measured the extracellular volume fraction (ECV) to quantify the extracellular matrix expansion in myocardium without myocardial infarction. ECV uses gadolinium contrast as an extracellular space marker based on T1 measures of blood and myocardium pre- and post-gadolinium contrast and hematocrit measurement. In volunteers, ECV ranged from 21.7% to 26.2%, but in patients it ranged from 21.0% to 45.8%, indicating considerable burden. There were 39 deaths over a median follow-up of 0.8 years (interquartile range 0.5-1.2 years), and 43 individuals who experienced the composite end point of death/cardiac transplant/left ventricular assist device implantation. In Cox regression models, ECV related to all-cause mortality and the composite end point (hazard ratio, 1.55; 95% confidence interval, 1.27-1.88 and hazard ratio, 1.48; 95% confidence interval, 1.23-1.78, respectively, for every 3% increase in ECV), adjusting for age, left ventricular ejection fraction, and myocardial infarction size.ConclusionsECV measures of extracellular matrix expansion may predict mortality as well as other composite end points (death/cardiac transplant/left ventricular assist device implantation).

In America, Dr. Thomas Antisell (1817–1893) is best known for his work as a geologist with the Pacific Railroad Survey under Lt. Parke. Prior to his participation with the survey, his background was in medicine, chemistry and geology, with accomplishments in all three areas, notably writing on the geology and soils of his native Ireland. As a political outcast, his arrival in America in 1854 found him teaching chemistry and practicing medicine, until his relationship with fellow Irish botanist and physician John Torrey landed him a position as geologist with that part of the survey exploring portions of southern California, notably the Coastal Range, and southern portions of Arizona and New Mexico. Although his involvement with the survey would be his last large-scale federally-sponsored geological endeavor, he would continue to pursue interests in applied geology, among his other varied interests in medicine and chemistry. These interests would include federal positions as Chemical Examiner with the United States Patent Office, Capital Chemist with the United States Department of Agriculture, surgeon during the Civil War, consultant as a Foreign Advisor in Japan, and Professor at Georgetown University, among other schools of medicine. Although many early American geologists received their academic education at medical schools, and were physicians that made career moves to geology and remained professional geologists throughout their career, Antisell was primarily a physician, with varied interests in applied chemistry and applied geology as evident from his writings. Thus, Antisell is one of America's early Medical Geologists; a term that would not become familiar and commonplace to the geological community until the 1990s. Moreover, as with other geologists of his time, he got some things right, and others not so, but his work set a geological foundation in new regions of the country, and raised questions that would eventually be addressed more fully by later investigators. [ABSTRACT FROM AUTHOR]

Research shows that a group I ribozyme from Pneumocystis carinii binds an RNA in trans and excises it from within an internal segment of 28 nucleotdies or longer or just one nucleotide length. Data indicate that the reaction is intramolecular and it occurs via a mechanism without involving a nucleotide cofactor.

Research has been conducted on the mammalian pathogen Pneumocystis carinii. The binding of the methylphosphonate/DNA chimeras and neutral methylphosphonate oligonucleotides to a ribozyme has been examined.

The effects of 2- and 4-thiouridine substitutions on tertiary interactions have been studied by measuring the binding to a group I intron ribozyme from mouse-derived Pneumocystis carinii. Results indicate that thiouridine substitutions can affect tertiary interactions.

Binding enhancement by tertiary interactions is a strategy that takes advantage of the higher order folding of functionally important RNAs to bind short nucleic acid-based compounds tightly and more specifically than possible by simple base pairing. For example, tertiary interactions enhance binding of specific hexamers to a group I intron ribozyme from the opportunistic pathogen Pneumocystis carinii by 1,000- to 100,000-fold relative to binding by only base pairing. One such hexamer, d(AnTnGnAnCn)rU, contains an N3[prime] [right arrow] P5[prime] phosphoramidate deoxysugar-phosphate backbone (n) that is resistant to chemical and enzymatic decay. Here, it is shown that this hexamer is also a suicide inhibitor of the intron's self-splicing reaction in vitro. The hexamer is ligated in trans to the 3[prime] exon of the precursor, producing dead-end products. At 4 mM [Mg.sup.2+], the fraction of trans-spliced product is greater than normally spliced product at hexamer concentrations as low as 200 nM. This provides an additional level of specificity for compounds that can exploit the catalytic potential of complexes with RNA targets.