Fructose metabolism as a common evolutionary pathway of survival associated with climate change, food shortage and droughts

Mass extinctions occur frequently in natural history. While studies of animals that became extinct can be informative, it is the survivors that provide clues for mechanisms of adaptation when conditions are adverse. Here, we describe a survival pathway used by many species as a means for providing adequate fuel and water, while also providing protection from a decrease in oxygen availability. Fructose, whether supplied in the diet (primarily fruits and honey), or endogenously (via activation of the polyol pathway), preferentially shifts the organism towards the storing of fuel (fat, glycogen) that can be used to provide energy and water at a later date. Fructose causes sodium retention and raises blood pressure and likely helped survival in the setting of dehydration or salt deprivation. By shifting energy production from the mitochondria to glycolysis, fructose reduced oxygen demands to aid survival in situations where oxygen availability is low. The actions of fructose are driven in part by vasopressin and the generation of uric acid. Twice in history, mutations occurred during periods of mass extinction that enhanced the activity of fructose to generate fat, with the first being a mutation in vitamin C metabolism during the Cretaceous-Paleogene extinction (65 million years ago) and the second being a mutation in uricase that occurred during the Middle Miocene disruption (12-14 million years ago). Today, the excessive intake of fructose due to the availability of refined sugar and high-fructose corn syrup is driving 'burden of life style' diseases, including obesity, diabetes and high blood pressure.

Directed evolution of polymerases to accept nucleotides with nonstandard hydrogen bond patterns

Artificial genetic systems have been developed by synthetic biologists over the past two decades to include additional nucleotides that form additional nucleobase pairs independent of the standard T:A and C:G pairs. Their use in various tools to detect and analyze DNA and RNA requires polymerases that synthesize duplex DNA containing unnatural base pairs. This is especially true for nested polymerase chain reaction (PCR), which has been shown to dramatically lower noise in multiplexed nested PCR if nonstandard nucleotides are used in their external primers. We report here the results of a directed evolution experiment seeking variants of Taq DNA polymerase that can support the nested PCR amplification with external primers containing two particular nonstandard nucleotides, 2-amino-8-(1'-β-d-2'-deoxyribofuranosyl)imidazo[1,2-a]-1,3,5-triazin-4(8H)-one (trivially called P) that pairs with 6-amino-5-nitro-3-(1'-β-d-2'-deoxyribofuranosyl)-2(1H)-pyridone (trivially called Z). Variants emerging from the directed evolution experiments were shown to pause less when challenged in vitro to incorporate dZTP opposite P in a template. Interestingly, several sites involved in the adaptation of Taq polymerases in the laboratory were also found to have displayed "heterotachy" (different rates of change) in their natural history, suggesting that these sites were involved in an adaptive change in natural polymerase evolution. Also remarkably, the polymerases evolved to be less able to incorporate dPTP opposite Z in the template, something that was not selected. In addition to being useful in certain assay architectures, this result underscores the general rule in directed evolution that "you get what you select for".

RNA-magnesium-protein interactions in large ribosomal subunit

Some of the magnesium ions in the ribosome are coordinated by multiple rRNA phosphate groups. These magnesium ions link distal sequences of rRNA, primarily by incorporating phosphate groups into the first coordination shell. Less frequently, magnesium interacts with ribosomal proteins. Ribosomal protein L2 appears to be unique by forming specific magnesium-mediated interactions with rRNA. Using optimized models derived from X-ray structures, we subjected rRNA/magnesium/water/rProtein L2 assemblies to quantum mechanical analysis using the density functional theory and natural energy decomposition analysis. The combined results provide estimates of energies of formation of these assemblies, and allow us to decompose the energies of interaction. The results indicated that RNA immobilizes magnesium by multidentate chelation with phosphate, and that the magnesium ions in turn localize and polarize water molecules, increasing energies and specificities of interaction of these water molecules with L2 protein. Thus, magnesium plays subtle, yet important, roles in ribosomal assembly beyond neutralization of electrostatic repulsion and direct coordination of RNA functional groups.

Diversity of chemical mechanisms in thioredoxin catalysis revealed by single-molecule force spectroscopy

Thioredoxins (Trxs) are oxidoreductase enzymes, present in all organisms, that catalyze the reduction of disulfide bonds in proteins. By applying a calibrated force to a substrate disulfide, the chemical mechanisms of Trx catalysis can be examined in detail at the single-molecule level. Here we use single-molecule force-clamp spectroscopy to explore the chemical evolution of Trx catalysis by probing the chemistry of eight different Trx enzymes. All Trxs show a characteristic Michaelis-Menten mechanism that is detected when the disulfide bond is stretched at low forces, but at high forces, two different chemical behaviors distinguish bacterial-origin from eukaryotic-origin Trxs. Eukaryotic-origin Trxs reduce disulfide bonds through a single-electron transfer reaction (SET), whereas bacterial-origin Trxs show both nucleophilic substitution (S(N)2) and SET reactions. A computational analysis of Trx structures identifies the evolution of the binding groove as an important factor controlling the chemistry of Trx catalysis.

The leader's role in implementing total quality management

Quality experts state that ineffective leadership can hinder and even destroy efforts to implement total quality management (TQM). However, they rarely discuss the specific actions leaders should take in implementing TQM and when leaders should take them. This article discusses a four-phase TQM implementation model that includes specifications for leadership actions at each step.

A vision for world-class quality in health care

When we talk about world-class health care, we are finding that we are in a position where the purchasers of our services find there is little or no value for the health-care dollars they are spending. Even the father of American Quality, W. Edwards Deming, has listed the high cost of health care as one of the seven deadly diseases, so we know that we are in trouble. According to a 1989 study, the public tells us that 32% of the time the value of health care they receive is good to excellent, and 65% of the time it is fair to poor. When we look at what our physicians say, 76% of them believe that we get good value for health-care dollars as opposed to 23% who think it is fair to poor. As I have been thinking about what world-class quality would mean, one of the things that comes to mind is the fact that health care is now consuming 15% of the gross national product. We are approaching an expenditure level of one trillion dollars. If our results were good, we could feel comfortable resting on our laurels, because for those we serve in the American health-care system, we serve them very well. But our results are not good. We are 23rd in the world in infant mortality, and we are 16th in the world for life expectancy. The real tragedy in the American health-care system is that 37 million Americans are uninsured. Obviously this cannot continue.(ABSTRACT TRUNCATED AT 250 WORDS)

Applying critical pathways to neurosurgery patients at the University of Michigan Medical Center

Project Overview: In April 1990, The University of Michigan Hospitals began a major, multidisciplinary project to standardize care processes in order to increase efficiency and reduce costs while maintaining the quality of clinical care. A team of nurses began the project by developing critical pathways for two neurosurgery procedures--lumbar laminectomy and transphenoidal pituitary tumor resection. The pathways were reviewed by physicians and other staff from other disciplines and were implemented in January of 1991.

KEY FINDINGS

Data from the first 14 months show a decrease in patients' average lengths of stay in both the intensive care unit (ICU) and routine care unit. Costs and variance data are being analyzed and further improvements to the pathways are being made. Eleven critical paths are now being used for neurosurgery patients. In retrospect, participants learned that physicians should be involved at the earliest stages of critical pathway development and in the process of implementation.

The practical zealot. Interview by Joe Flower

In 1987, Ellen Gaucher took an unusual trip. As senior associate director of the University of Michigan's sprawling 11,000-employee Medical Center, she was invited to a conference about a movement that was rapidly growing in the word of business--total quality. The occasion was the organizational conference of the National Demonstration Project on Quality Improvement in Health Care, led by the Harvard Community Health Plan in Boston. Gaucher was skeptical at first. Total quality seemed a great way to make better cars, light bulbs, and aluminum siding, but would it work in a service industry? More to the point, would it work in an industry as complex, as critical, as pressured, as high-tech, as human, and as intellectual as healthcare? But by the second day, she says, "I was sold that this was what we had needed for a long time." She hurried back to Michigan like a missionary trekking into cannibal country. Today, not only is the University Medical Center deep in a total quality conversion experience, so is the University itself, through its president, James J. Duderstadt. He was exposed to the idea through Gaucher: In his ex-officio position as chairman of the Medical Center's board, he had experienced her vivid and enthusiastic educational efforts. Gaucher has related her intense experiences with TQ at conferences, in articles, in the 1990 book, Transforming Healthcare Organizations (winner of the Hamilton Award given by the American College of Healthcare Executives for the best book of the year) as well as the forthcoming Total Quality in Healthcare (both co-authored with Richard Coffey). (ABSTRACT TRUNCATED AT 250 WORDS)