bluuebunny/crossref_metadata_2025 huggingface dataset:
PATHWAYS, MECHANISMS, AND RATES OF POLYPLOID FORMATION IN FLOWERING PLANTS
Authors: Ramsey Justin , Schemske Douglas W.
Published: July 2002

▪ Abstract  Polyploidy is widely acknowledged as a major mechanism of adaptation and speciation in plants. The stages in polyploid evolution include frequent fertility bottlenecks and infrequent events such as gametic nonreduction and interspecific hybridization, yet little is known about how these and other factors influence overall rates of polyploid formation. Here we review the literature regarding polyploid origins, and quantify parameter values for each of the steps involved in the principal pathways. In contrast to the common claim that triploids are sterile, our results indicate that the triploid bridge pathway can contribute significantly to autopolyploid formation regardless of the mating system, and to allopolyploid formation in outcrossing taxa. We estimate that the total rate of autotetraploid formation is of the same order as the genic mutation rate (10−5), and that a high frequency of interspecific hybridization (0.2% for selfing taxa, 2.7% for outcrossing taxa) is required for the rate of tetraploid formation via allopolyploidy to equal that by autopolyploidy. We conclude that the rate of autopolyploid formation may often be higher than the rate of allopolyploid formation. Further progress toward understanding polyploid origins requires studies in natural populations that quantify: (a) the frequency of unreduced gametes, (b) the effectiveness of triploid bridge pathways, and (c) the rates of interspecific hybridization.
The Population Biology of Invasive Species
Authors: Sakai Ann K. , Allendorf Fred W. , Holt Jodie S. , Lodge David M. , Molofsky Jane , With Kimberly A. , Baughman Syndallas , Cabin Robert J. , Cohen Joel E. , Ellstrand Norman C. , McCauley David E. , O'Neil Pamela , Parker Ingrid M. , Thompson John N. , Weller Stephen G.
Published: July 2002

▪ Abstract  Contributions from the field of population biology hold promise for understanding and managing invasiveness; invasive species also offer excellent opportunities to study basic processes in population biology. Life history studies and demographic models may be valuable for examining the introduction of invasive species and identifying life history stages where management will be most effective. Evolutionary processes may be key features in determining whether invasive species establish and spread. Studies of genetic diversity and evolutionary changes should be useful for understanding the potential for colonization and establishment, geographic patterns of invasion and range expansion, lag times, and the potential for evolutionary responses to novel environments, including management practices. The consequences of biological invasions permit study of basic evolutionary processes, as invaders often evolve rapidly in response to novel abiotic and biotic conditions, and native species evolve in response to the invasion.
HUMAN EXPOSURE TO VOLATILE ORGANIC POLLUTANTS: Implications for Indoor Air Studies
Authors: Wallace Lance A.
Published: July 2002

▪ Abstract  Over the past 20 years, a new scientific discipline based on direct measurement of human exposure to environmental pollutants has developed. The fundamental principle of the new science is to “measure where the people are.” This has required developing small, lightweight, quiet personal monitors for volatile organic compounds and other pollutants. A second principle has been to measure body burden, particularly exhaled breath, whenever possible to determine the relationship between exposure and dose. Studies employing the new monitors and breath measurements have overturned accepted ideas about the sources of most volatile organic pollutants. The main sources turn out surprisingly often to be small, close to the person, and completely unregulated. These findings should result in major changes in our approach to environmental regulation; however, powerful forces of resistance would need to be overcome.
HOST PLANT INFLUENCES ON SEX PHEROMONE BEHAVIOR OF PHYTOPHAGOUS INSECTS
Authors: Landolt Peter J. , Phillips Thomas W.
Published: July 2002

▪ Abstract  The sexual behavior of phytophagous insects is often integrated in a variety of ways with their host plants. This integration may be manifested as effects or influences of host plants on insect physiology and behavior, including sex pheromone communication, that reflect strategies by insects to optimize mating and reproduction. Certain insects sequester or otherwise acquire host plant compounds and use them as sex pheromones or sex pheromone precursors. Other insects produce or release sex pheromones in response to particular host plant cues. Chemicals from host plants often synergize or otherwise enhance insect responses to sex pheromones. By these means, host plants may be used by insects to regulate or mediate sexual communication.

For many species of insects, host plant influences on insect sex pheromone communication may be important aspects of the formation of feeding and mating aggregations, of insect strategies to locate both hosts and mates, of behavioral reproductive isolation among sibling species, and of the regulation of reproduction to coincide with the availability of food and oviposition sites. Knowledge of these relationships is critical to understanding many different areas of the behavioral ecology of plant-feeding insects.
Golden Age of Insecticide Research: Past, Present, or Future?
Authors: Casida John E. , Quistad Gary B.
Published: July 2002

▪ Abstract  Insecticide research led to the first “complete” victories in combatting pests almost 50 years ago with the chlorinated hydrocarbons followed quickly by the organophosphates, methylcarbamates, and pyrethroids—all neuroactive chemicals. This Golden Age of Discovery was the source of most of our current insecticides. The challenge then became health and the environment, a Golden Age met with selective and degradable compounds. Next the focus shifted to resistance, novel biochemical targets, and new chemical approaches for pest control. The current Golden Age of Genetic Engineering has curtailed, but is unlikely to eliminate, chemical use on major crops. Insecticide research, having passed through several Golden Ages, is now in a renaissance of integrating chemicals and biologicals for sustainable pest control with human safety.
Integrated Pest Management: Historical Perspectives and Contemporary Developments
Authors: Kogan Marcos
Published: July 2002

Twenty five years after its first enunciation, IPM is recognized as one of the most robust constructs to arise in the agricultural sciences during the second half of the twentieth century. The history of IPM, however, can be traced back to the late 1800s when ecology was identified as the foundation for scientific plant protection. That history, since the advent of modern organosynthetic pesticides, acquired elements of drama, intrigue, jealousy, and controversy that mark the path of many great scientific or technological achievements. Evolution of IPM followed multiple paths in several countries and reached beyond the confines of entomological sciences. Time and space constraints, however, bias this review toward entomology, among the plant protection sciences, and give it an obvious US slant, despite the global impact of IPM.
Manipulating Natural Enemies By Plant Variety Selection and Modification: A Realistic Strategy?
Authors: Bottrell Dale G. , Barbosa Pedro , Gould Fred
Published: July 2002

▪ Abstract  The host plants of arthropod pests may affect parasitoids and predators directly or indirectly, through multitrophic interactions. Direct plant effects may involve simple mechanisms such as reduced parasitoid searching efficiency caused by trichomes. Multitrophic effects often involve complex interactions that are not well understood, and their impact on natural enemies and biological control are difficult to predict. Knowledge of the direct and multitrophic effects creates opportunities to increase the effectiveness of natural enemies by incorporating natural enemy–enhancing traits into crop plants. The strategy may have potential for both generalist and specialist natural enemies, but the enemies' behavior and other factors will affect the results. Although combining natural enemies and plant resistance may slow the adaptation of some insect pests, it may speed up adaptations of others. A better understanding of plant/pest/natural enemy evolution is necessary to predict how to combine natural enemies and plant resistance for the best long-term results.
BIOLOGICAL CONTROL OF WEEDS
Authors: McFadyen Rachel E. Cruttwell
Published: July 2002

▪ Abstract  Classical biological control, i.e. the introduction and release of exotic insects, mites, or pathogens to give permanent control, is the predominant method in weed biocontrol. Inundative releases of predators and integrated pest management are less widely used. The United States, Australia, South Africa, Canada, and New Zealand use biocontrol the most. Weeds in natural ecosystems are increasingly becoming targets for biocontrol. Discussion continues on agent selection, but host-specificity testing is well developed and reliable. Post-release evaluation of impact is increasing, both on the target weed and on non-target plants. Control of aquatic weeds has been a notable success. Alien plant problems are increasing worldwide, and biocontrol offers the only safe, economic, and environmentally sustainable solution.
SPATIAL HETEROGENEITY AND INSECT ADAPTATION TO TOXINS
Authors: Hoy Casey W. , Head Graham P. , Hall Franklin R.
Published: July 2002

▪ Abstract  Behavioral responses of insect herbivores to toxins are examined in managed and natural systems with reference to two important but largely ignored factors: heterogeneity in toxin distributions and the nature of the relationship between behavioral responses and physiological adaptation to the same toxins. Heterogeneous toxin distributions, which provide the opportunity for behavioral responses, are ubiquitous in managed and natural systems. Insect herbivores have evolved a wide variety of behavioral responses to such toxins. The nature of behavioral responses reflects toxin apparency, mode of action, and the extent to which sublethal effects influence behavior. The interaction between these behavioral responses to heterogeneously distributed toxins and physiological mechanisms of tolerance has influenced the evolution of insecticide resistance in managed systems and the evolution of plant defensive strategies in natural systems. An understanding of this interaction could lead to more evolutionarily stable methods of crop protection.
THE ROLE OF STINGLESS BEES IN CROP POLLINATION
Authors: Heard Tim A.
Published: July 2002

▪ Abstract  Stingless bees (Apidae: Meliponini) are common visitors to flowering plants in the tropics, but evidence for their importance and effectiveness as crop pollinators is lacking for most plant species. They are known to visit the flowers of ∼90 crop species. They were confirmed to be effective and important pollinators of 9 species. They may make a contribution to the pollination of ∼60 other species, but there is insufficient information to determine their overall effectiveness or importance. They have been recorded from another 20 crops, but other evidence suggests that they do not have an important role because these plants are pollinated by other means. The strengths and limitations of stingless bees as crop pollinators are discussed. Aspects of their biology that impact on their potential for crop pollination are reviewed, including generalized flower visiting behavior of colonies, floral constancy of individual bees, flight range, and the importance of natural vegetation for maintaining local populations.
Medicinal Maggots: An Ancient Remedy for Some Contemporary Afflictions
Authors: Sherman R. A. , Hall M. J. R. , Thomas S.
Published: July 2002

▪ Abstract  Certain fly larvae can infest corpses or the wounds of live hosts. Those which are least invasive on live hosts have been used therapeutically, to remove dead tissue from wounds, and promote healing. This medicinal use of maggots is increasing around the world, due to its efficacy, safety and simplicity. Given our low cultural esteem for maggots, the increasing use and popularity of maggot therapy is evidence of its utility. Maggot therapy has successfully treated many types of chronic wounds, but much clinical and basic research is needed still. In this review, the biology of myiasis and the history of maggot therapy are presented, the current status of our understanding and clinical use of medicinal maggots is discussed, and opportunities for future research and applications are proposed.
QUANTIFICATION OF UNCERTAINTY IN COMPUTATIONAL FLUID DYNAMICS
Authors: Roache P. J.
Published: July 2002

▪ Abstract  This review covers Verification, Validation, Confirmation and related subjects for computational fluid dynamics (CFD), including error taxonomies, error estimation and banding, convergence rates, surrogate estimators, nonlinear dynamics, and error estimation for grid adaptation vs Quantification of Uncertainty.
MAGNETOHYDRODYNAMICS IN MATERIALS PROCESSING
Authors: Davidson P. A.
Published: July 2002

▪ Abstract  Magnetic fields can be used to melt, pump, stir, and stabilize liquid metals. This provides a nonintrusive means of controlling the flow of metal in commercial casting and refining operations. The quest for greater efficiency and more control in the production of steel, aluminum, and high-performance superalloys has led to a revolution in the application of magnetohydrodynamics (MHD) to process metallurgy. Three typical applications are described here, chosen partially on the basis of their general interest to fluid dynamicists, and partially because of their considerable industrial importance. We look first at magnetic stirring, where a rotating magnetic field is used to agitate and homogenize the liquid zone of a partially-solidified ingot. This is a study in Ekman pumping. Next, we consider magnetic damping, where an intense, static magnetic field is used to suppress fluid motion. In particular, we look at the damping of jets, vortices, and turbulence. We conclude with a discussion of the magnetic destabilization of liquid-liquid interfaces. This is of particular importance in aluminum production.
Scale-Invariance and Turbulence Models for Large-Eddy Simulation
Authors: Meneveau Charles , Katz Joseph
Published: July 2002

▪ Abstract  Relationships between small and large scales of motion in turbulent flows are of much interest in large-eddy simulation of turbulence, in which small scales are not explicitly resolved and must be modeled. This paper reviews models that are based on scale-invariance properties of high-Reynolds-number turbulence in the inertial range. The review starts with the Smagorinsky model, but the focus is on dynamic and similarity subgrid models and on evaluating how well these models reproduce the true impact of the small scales on large-scale physics and how they perform in numerical simulations. Various criteria to evaluate the model performance are discussed, including the so-called a posteriori and a priori studies based on direct numerical simulation and experimental data. Issues are addressed mainly in the context of canonical, incompressible flows, but extensions to scalar-transport, compressible, and reacting flows are also mentioned. Other recent modeling approaches are briefly introduced.
Shock Wave—Turbulence Interactions
Authors: Andreopoulos Yiannis , Agui Juan H. , Briassulis George
Published: July 2002

▪ Abstract  The idealized interactions of shock waves with homogeneous and isotropic turbulence, homogeneous sheared turbulence, turbulent jets, shear layers, turbulent wake flows, and two-dimensional boundary layers have been reviewed. The interaction between a shock wave and turbulence is mutual. A shock wave exhibits substantial unsteadiness and deformation as a result of the interaction, whereas the characteristic velocity, timescales and length scales of turbulence change considerably. The outcomes of the interaction depend on the strength, orientation, location, and shape of the shock wave, as well as the flow geometry and boundary conditions. The state of turbulence and the compressibility of the incoming flow are two additional parameters that also affect the interaction.
JUNCTION FLOWS
Authors: Simpson Roger L
Published: July 2002

▪ Abstract  Junction flows occur when a boundary layer encounters an obstacle attached to the same surface. Physical phenomena that have been observed for blunt and streamlined obstacles are discussed for both laminar and turbulent approaching boundary layers. The pressure gradients around an obstacle produce a three-dimensional separation with horseshoe vortices that wrap around the obstacle. Except for very low Reynolds number laminar flows, these vortices are highly unsteady and are responsible for high turbulence intensities, high surface pressure fluctuations and heat transfer rates, and erosion scour in the nose region of the obstacle. Calculation methods are also reviewed; methods that capture the large-scale chaotic vortical motions should be used for computations. Some work on the control, modification, or elimination of such vortices is also reviewed.
Sir Francis Galton and the Birth of Eugenics
Authors: Gillham Nicholas W.
Published: July 2002

▪ Abstract  The eugenics movement was initiated by Sir Francis Galton, a Victorian scientist. Galton's career can be divided into two parts. During the first, Galton was engaged in African exploration, travel writing, geography, and meteorology. The second part began after he read the Origin of Species by his cousin Charles Darwin. The book convinced Galton that humanity could be improved through selective breeding. During this part of his career he was interested in the factors that determine what he called human “talent and character” and its hereditary basis. Consequently, he delved into anthropometrics and psychology and played a major role in the development of fingerprinting. He also founded the field of biometrics, inventing such familiar statistical procedures as correlation and regression analysis. He constructed his own theory of inheritance in which nature and not nurture played the leading role. He actively began to promote eugenics and soon gained important converts.
LEUKOCYTE PROTEIN TYROSINE KINASES:Potential Targets for Drug Discovery
Authors: Bolen Joseph B. , Brugge Joan S.
Published: July 2002

▪ Abstract  Intracellular signal transduction following the extracellular ligation of a wide variety of different types of surface molecules on leukocytes involves the activation of protein tyrosine kinases. The dependence of successful intracellular signaling on the functions of the nontransmembrane class of protein tyrosine kinases coupled with the cell type–specific expression patterns for several of these enzymes makes them appealing targets for therapeutic intervention. Development of drugs that can interfere with the catalytic functions of the nontransmembrane protein tyrosine kinases or that can disrupt critical interactions with regulatory molecules and/or substrates should find clinical applications in the treatment of allergic diseases, autoimmunity, transplantation rejection, and cancer.
Cross-Presentation, Dendritic Cells, Tolerance and Immunity
Authors: Heath William R. , Carbone Francis R.
Published: July 2002

This review examines the role of cross-presentation in tolerance and immunity. We discuss (a) the antigenic requirements for cross-presentation, (b) the phenotype of the antigen presenting cell (APC), (c) the cellular interactions and molecular signals involved in cross-priming, and (d) the factors that direct the immune system toward tolerance or immunity. A large part of this review is dedicated to summarizing our current knowledge of the cross-presenting APC.
Synthesis and Design of Superhard Materials
Authors: Haines J , Léger JM , Bocquillon G
Published: July 2002

▪ Abstract  The synthesis of the two currently used superhard materials, diamond and cubic boron nitride, is briefly described with indications of the factors influencing the quality of the crystals obtained. The physics of hardness is discussed and the importance of covalent bonding and fixed atomic positions in the crystal structure, which determine high hardness values, is outlined. The materials investigated to date are described and new potentially superhard materials are presented. No material that is thermodynamically stable under ambient conditions and composed of light (small) atoms will have a hardness greater than that of diamond. Materials with hardness values similar to that of cubic boron nitride (cBN) can be obtained. However, increasing the capabilities of the high-pressure devices could lead to the production of better quality cBN compacts without binders.
TUMOR NECROSIS FACTOR: A Pleiotropic Cytokine and Therapuetic Target
Authors: Tracey, M.D Kevin J. , Cerami, Ph.D Anthony
Published: July 2002

▪ Abstract  Advances in the molecular biology of human diseases indicate that the most striking manifestations of illness may be caused not by exogenous pathogenic or tumor porducts, but rather by toxic peptides produced by the host itself. Tumor necrosis factor (TNF), a polypeptide cytokine produced during infection, injury, or invasion, has proved spivotal in triggering the lethal effects of septic shock syndrome, cachexia, and other systemic manifestations of disease. Because removing TNF from the diseased host may prevent development of the illness, this factor has recently been the focus of intensive research. This review discusses the biology of this cytokine, with particular emphasis on its potential therapeutic role in septic shock and cachexia.
The Cytoskeleton of Trypanosomatid Parasites
Authors: Gull Keith
Published: July 2002

▪ Abstract  Species of the trypanosomatid parasite genera Trypanosoma and Leishmania exhibit a particular range of cell shapes that are defined by their internal cytoskeletons. The cytoskeleton is characterized by a subpellicular corset of microtubules that are cross-linked to each other and to the plasma membrane. Trypanosomatid cells possess an extremely precise organization of microtubules and filaments, with some of their organelles, such as the mitochondria, kinetoplasts, basal bodies, and flagella, present as single copies in each cell. The duplication of these structures and changes in their position during life cycle differentiations provide markers and insight into events involved in determining cell form and division. We have a rapidly increasing catalog of these structures, their molecular cytology, and their ontogeny. The current sophistication of available molecular genetic techniques for use in these organisms has allowed a new functional analysis of the cytoskeleton, including functions that are intrinsic to the proliferation and pathogenicity of these parasites.
BCL-2 GENE FAMILY IN THE NERVOUS SYSTEM
Authors: Merry D. E. , Korsmeyer S. J.
Published: July 2002

▪ Abstract  A growing family of genes that share homology with the bcl-2 proto-oncogene is involved in the regulation of cell death. Many of these proteins show widespread expression and are expressed in the nervous system in developing and adult organisms. A physiologic role for Bcl-2 and Bcl-x in neuron survival has been shown. In addition, these proteins have been shown to protect neurons from a wide array of toxic insults. In this review, we discuss the Bcl-2 family of proteins with regard to their structure and interactions. We then discuss the role of apoptotic cell death in the development of the nervous system and as a response to neuronal injury. Lastly, we discuss the evidence for a role for these cell death regulators in neuronal death decisions.
MECHANISMS OF OLFACTORY DISCRIMINATION: Converging Evidence for Common Principles Across Phyla
Authors: Hildebrand John G. , Shepherd Gordon M.
Published: July 2002

▪ Abstract  Olfaction begins with the transduction of the information carried by odor molecules into electrical signals in sensory neurons. The activation of different subsets of sensory neurons to different degrees is the basis for neural encoding and further processing of the odor information by higher centers in the olfactory pathway. Recent evidence has converged on a set of transduction mechanisms, involving G-protein-coupled second-messenger systems, and neural processing mechanisms, involving modules called glomeruli, that appear to be adapted for the requirements of different species. The evidence is highlighted in this review by focusing on studies in selected vertebrates and in insects and crustaceans among invertebrates. The findings support the hypothesis that olfactory transduction and neural processing in the peripheral olfactory pathway involve basic mechanisms that are universal across most species in most phyla.
MONOAMINE OXIDASE: From Genes to Behavior
Authors: Shih J. C. , Chen K. , Ridd M. J.
Published: July 2002

▪ Abstract  Cloning of MAO (monoamine oxidase) A and B has demonstrated unequivocally that these enzymes are made up of different polypeptides, and our understanding of MAO structure, regulation, and function has been significantly advanced by studies using their cDNA. MAO A and B genes are located on the X-chromosome (Xp11.23) and comprise 15 exons with identical intron-exon organization, which suggests that they are derived from the same ancestral gene. MAO A and B knock-out mice exhibit distinct differences in neurotransmitter metabolism and behavior. MAO A knock-out mice have elevated brain levels of serotonin, norephinephrine, and dopamine and manifest aggressive behavior similar to human males with a deletion of MAO A. In contrast, MAO B knock-out mice do not exhibit aggression and only levels of phenylethylamine are increased. Mice lacking MAO B are resistant to the Parkinsongenic neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Both MAO A and B knock-out mice show increased reactivity to stress. These knock-out mice are valuable models for investigating the role of monoamines in psychoses and neurodegenerative and stress-related disorders.
RETINAL WAVES AND VISUAL SYSTEM DEVELOPMENT
Authors: Wong Rachel O. L.
Published: July 2002

▪ Abstract  Many pathways in the developing visual system are restructured and become highly organized even before vision occurs. Yet the developmental processes underlying the remodeling of visual connectivity are crucially dependent on retinal activity. Surprisingly, the immature and light-insensitive retina spontaneously generates a pattern of rhythmic bursting activity during the period when the connectivity patterns of retinal ganglion cells are shaped. Spatially, the activity is seen to spread across the retina in the form of waves that bring into synchrony the bursts of neighboring cells. Waves are present in the developing retina of higher and lower vertebrates, which suggests that this form of activity may be a common and fundamental mechanism employed in the activity-dependent refinement of early patterns of visual connections. Unraveling the cues encoded by the waves promises to provide important insights into how interactions driven by specific patterns of activity could lead to the modification of connectivity during development.
Consciousness
Authors: Searle John R.
Published: July 2002

Until recently, most neuroscientists did not regard consciousness as a suitable topic for scientific investigation. This reluctance was based on certain philosophical mistakes, primarily the mistake of supposing that the subjectivity of consciousness made it beyond the reach of an objective science. Once we see that consciousness is a biological phenomenon like any other, then it can be investigated neurobiologically. Consciousness is entirely caused by neurobiological processes and is realized in brain structures. The essential trait of consciousness that we need to explain is unified qualitative subjectivity. Consciousness thus differs from other biological phenomena in that it has a subjective or first-person ontology, but this subjective ontology does not prevent us from having an epistemically objective science of consciousness. We need to overcome the philosophical tradition that treats the mental and the physical as two distinct metaphysical realms. Two common approaches to consciousness are those that adopt the building block model, according to which any conscious field is made of its various parts, and the unified field model, according to which we should try to explain the unified character of subjective states of consciousness. These two approaches are discussed and reasons are given for preferring the unified field theory to the building block model. Some relevant research on consciousness involves the subjects of blindsight, the split-brain experiments, binocular rivalry, and gestalt switching.
TOXIC AND ESSENTIAL METAL INTERACTIONS
Authors: Goyer Robert A.
Published: July 2002

▪ Abstract  Cadmium, lead, mercury, and aluminum are toxic metals that may interact metabolically with nutritionally essential metals. Iron deficiency increases absorption of cadmium, lead, and aluminum. Lead interacts with calcium in the nervous system to impair cognitive development. Cadmium and aluminum interact with calcium in the skeletal system to produce osteodystrophies. Lead replaces zinc on heme enzymes and cadmium replaces zinc on metallothionein. Selenium protects from mercury and methylmercury toxicity. Aluminum interacts with calcium in bone and kidneys, resulting in aluminum osteodystrophy. Calcium deficiency along with low dietary magnesium may contribute to aluminum-induced degenerative nervous disease.
INTERRELATIONSHIPS OFKEYVARIABLES OFHUMANZINCHOMEOSTASIS: Relevance to Dietary Zinc Requirements
Authors: Hambidge Michael , Krebs Nancy F
Published: July 2002

▪ Abstract  Currently, estimates of human zinc requirements depend primarily on a factorial approach. The availability of tracer techniques employing zinc stable isotopes has facilitated the acquisition of data on major variables of zinc homeostasis in addition to those that can be measured with careful metabolic balance techniques. These data have promising potential to facilitate and improve the factorial approach. The thesis proposed in this paper is that realistic estimations of dietary zinc requirements by a factorial approach require attention to the dynamic interrelationships between major variables of zinc homeostasis. This applies especially to the positive relationship between endogenous fecal zinc and total absorbed zinc, which is the essential starting point in estimating physiologic and, from there, dietary requirements.
PHYTOSTEROLS INHUMANNUTRITION
Authors: Ostlund Richard E.
Published: July 2002

▪ Abstract  Phytosterols are cholesterol-like molecules found in all plant foods, with the highest concentrations occurring in vegetable oils. They are absorbed only in trace amounts but inhibit the absorption of intestinal cholesterol including recirculating endogenous biliary cholesterol, a key step in cholesterol elimination. Natural dietary intake varies from about 167–437 mg/day. Attempts to measure biological effects in feeding studies have been impeded by limited solubility in both water and fat. Esterification of phytosterols with long-chain fatty acids increases fat solubility by 10-fold and allows delivery of several grams daily in fatty foods such as margarine. A dose of 2 g/day as the ester reduces low density lipoprotein cholesterol by 10%, and little difference is observed between Δ5-sterols and 5α-reduced sterols (stanols). Phytosterols can also be dispersed in water after emulsification with lecithin and reduce cholesterol absorption when added to nonfat foods. In contrast to these supplementation studies, much less is known about the effect of low phytosterol levels in the natural diet. However, reduction of cholesterol absorption can be measured at a dose of only 150 mg during otherwise sterol-free test meals, suggesting that natural food phytosterols may be clinically important. Current literature suggests that phytosterols are safe when added to the diet, and measured absorption and plasma levels are very small. Increasing the aggregate amount of phytosterols consumed in a variety of foods may be an important way of reducing population cholesterol levels and preventing coronary heart disease.
CYCLOOXYGENASES 1 AND 2
Authors: Vane J. R. , Bakhle Y. S. , Botting R. M.
Published: July 2002

▪ Abstract  Cyclooxygenase (COX), first purified in 1976 and cloned in 1988, is the key enzyme in the synthesis of prostaglandins (PGs) from arachidonic acid. In 1991, several laboratories identified a product from a second gene with COX activity and called it COX-2. However, COX-2 was inducible, and the inducing stimuli included pro-inflammatory cytokines and growth factors, implying a role for COX-2 in both inflammation and control of cell growth. The two isoforms of COX are almost identical in structure but have important differences in substrate and inhibitor selectivity and in their intracellular locations. Protective PGs, which preserve the integrity of the stomach lining and maintain normal renal function in a compromised kidney, are synthesized by COX-1. In addition to the induction of COX-2 in inflammatory lesions, it is present constitutively in the brain and spinal cord, where it may be involved in nerve transmission, particularly that for pain and fever. PGs made by COX-2 are also important in ovulation and in the birth process. The discovery of COX-2 has made possible the design of drugs that reduce inflammation without removing the protective PGs in the stomach and kidney made by COX-1. These highly selective COX-2 inhibitors may not only be anti-inflammatory but may also be active in colon cancer and Alzheimer's disease.
Molecular Basis of Ethnic Differences in Drug Disposition and Response
Authors: Xie Hong-Guang , Kim Richard B , Wood Alastair JJ , Stein C Michael
Published: July 2002

Ethnicity is an important demographic variable contributing to interindividual variability in drug metabolism and response. In this rapidly expanding research area many genetic factors that account for the effects of ethnicity on pharmacokinetics, pharmacodynamics, and drug safety have been identified. This review focuses on recent developments that have improved understanding of the molecular mechanisms responsible for such interethnic differences. Genetic variations that may provide a molecular basis for ethnic differences in drug metabolizing enzymes (CYP 2C9, 2C19, 2D6, and 3A4), drug transporter (P-glycoprotein), drug receptors (adrenoceptors), and other functionally important proteins (eNOS and G proteins) are discussed. A better understanding of the molecular basis underlying ethnic differences in drug metabolism, transport, and response will contribute to improved individualization of drug therapy.
Spatially Heterogeneous Dynamics in Supercooled Liquids
Authors: Ediger M. D.
Published: July 2002

Although it has long been recognized that dynamics in supercooled liquids might be spatially heterogeneous, only in the past few years has clear evidence emerged to support this view. As a liquid is cooled far below its melting point, dynamics in some regions of the sample can be orders of magnitude faster than dynamics in other regions only a few nanometers away. In this review, the experimental work that characterizes this heterogeneity is described. In particular, the following questions are addressed: How large are the heterogeneities? How long do they last? How much do dynamics vary between the fastest and slowest regions? Why do these heterogeneities arise? The answers to these questions influence practical applications of glass-forming materials, including polymers, metallic glasses, and pharmaceuticals.
BIOMOLECULAR SOLID STATE NMR: Advances in Structural Methodology and Applications to Peptide and Protein Fibrils
Authors: Tycko Robert
Published: July 2002

▪ Abstract  Solid state nuclear magnetic resonance (NMR) methods can provide atomic-level structural constraints on peptides and proteins in forms that are not amenable to characterization by other high-resolution structural techniques, owing to insolubility, high molecular weight, noncrystallinity, or other characteristics. Important examples include peptide and protein fibrils and membrane-bound peptides and proteins. Recent advances in solid state NMR methodology aimed at structural problems in biological systems are reviewed. The power of these methods is illustrated by experimental results on amyloid fibrils and other protein fibrils.
THE IMPACT OF REDUCED TILLAGE ON SOILBORNE PLANT PATHOGENS
Authors: Bockus W. W. , Shroyer J. P.
Published: July 2002

▪ Abstract  Farmers increasingly leave crop residues on the soil surface rather than incorporating them into the soil. This practice helps reduce soil erosion, conserve energy, increase soil moisture, and increase crop yields. However, many soilborne plant pathogens survive in the previous year's crop residue, making diseases more problematic under reduced-tillage conditions. Reduced tillage can favor pathogens by such mechanisms as protecting the pathogen's refuge in the residue from microbial degradation, lowering soil temperature, increasing soil moisture, and leaving soil undisturbed. In order for reduced tillage to become more popular, additional controls are needed for pathogens. The four major control tactics (disease-control chemicals, biological control, host resistance, and cultural controls) can be used to limit damage from diseases. It is highly recommended, however, that crop rotation be coupled with reduced tillage. This practice controls many diseases and yet allows as much of the crop residue as possible to be retained on the soil surface.
The Photoactivated Cercospora Toxin Cercosporin: Contributions to Plant Disease and Fundamental Biology
Authors: Daub Margaret E. , Ehrenshaft Marilyn
Published: July 2002

Plant pathogenic fungi in eight genera produce light-activated perylenequinone toxins that are toxic to plants via the generation of activated oxygen species, particularly singlet oxygen. Studies on the cercosporin toxin produced by Cercospora species have documented an important role for this toxin in pathogenesis of host plants. Cercosporin-generated active oxygen species destroy the membranes of host plants, providing nutrients to support the growth of these intercellular pathogens. Resistance of Cercospora species to the toxic effects of their own toxin has allowed these organisms to be used as a model for understanding the cellular basis of resistance to singlet oxygen and to general oxidative stress. In particular, the recent discovery that pyridoxine (vitamin B6) quenches singlet oxygen has led to the understanding of a novel role for this vitamin in cells as well as the discovery of a novel pathway of biosynthesis.
CONFLICT IN MARRIAGE: Implications for Working with Couples
Authors: Fincham Frank D. , Beach Steven R. H.
Published: July 2002

▪ Abstract  The investigation of marital conflict has reached a crossroads. Over 25 years of research on marital conflict behavior yields a relatively clear picture of its topography, but its relevance for changing the marital relationship remains controversial. We can continue to amass observations in a relatively atheoretical manner and hope that patterns capable of guiding clinical activity will emerge, or we can begin creating a unified theoretical framework to indicate new directions for clinical activity and empirical investigation. Before exploring the latter option, this chapter reviews briefly the impact of marital conflict on mental, physical, and family health and what is known about the nature of conflict in marriage. After highlighting some recent theoretically grounded advances, we illustrate how conceptualizing marital conflict behavior as goal directed provides an integrative theoretical framework for treatment, prevention, and marital conflict research.
Remembering Over the Short-Term: The Case Against the Standard Model
Authors: Nairne James S.
Published: July 2002

▪ Abstract  Psychologists often assume that short-term storage is synonymous with activation, a mnemonic property that keeps information in an immediately accessible form. Permanent knowledge is activated, as a result of on-line cognitive processing, and an activity trace is established “in” short-term (or working) memory. Activation is assumed to decay spontaneously with the passage of time, so a refreshing process—rehearsal—is needed to maintain availability. Most of the phenomena of immediate retention, such as capacity limitations and word length effects, are assumed to arise from trade-offs between rehearsal and decay. This “standard model” of how we remember over the short-term still enjoys considerable popularity, although recent research questions most of its main assumptions. In this chapter I review the recent research and identify the empirical and conceptual problems that plague traditional conceptions of short-term memory. Increasingly, researchers are recognizing that short-term retention is cue driven, much like long-term memory, and that neither rehearsal nor decay is likely to explain the particulars of short-term forgetting.
Latent Variables in Psychology and the Social Sciences
Authors: Bollen Kenneth A.
Published: July 2002

▪ Abstract  The paper discusses the use of latent variables in psychology and social science research. Local independence, expected value true scores, and nondeterministic functions of observed variables are three types of definitions for latent variables. These definitions are reviewed and an alternative “sample realizations” definition is presented. Another section briefly describes identification, latent variable indeterminancy, and other properties common to models with latent variables. The paper then reviews the role of latent variables in multiple regression, probit and logistic regression, factor analysis, latent curve models, item response theory, latent class analysis, and structural equation models. Though these application areas are diverse, the paper highlights the similarities as well as the differences in the manner in which the latent variables are defined and used. It concludes with an evaluation of the different definitions of latent variables and their properties.
Diffusion in Organizations and Social Movements: From Hybrid Corn to Poison Pills
Authors: Strang David , Soule Sarah A.
Published: July 2002

There has been rapid growth in the study of diffusion across organizations and social movements in recent years, fueled by interest in institutional arguments and in network and dynamic analysis. This research develops a sociologically grounded account of change emphasizing the channels along which practices flow. Our review focuses on characteristic lines of argument, emphasizing the structural and cultural logic of diffusion processes. We argue for closer theoretical attention to why practices diffuse at different rates and via different pathways in different settings. Three strategies for further development are proposed: broader comparative research designs, closer inspection of the content of social relations between collective actors, and more attention to diffusion industries run by the media and communities of experts.
Narrative Analysis—Or Why (and How) Sociologists Should Be Interested In Narrative
Authors: Franzosi Roberto
Published: July 2002

In this paper I explore the questions of why and how sociologists should be interested in narrative. The answer to the first question is straightforward: Narrative texts are packed with sociological information, and a great deal of our empirical evidence is in narrative form. In an attempt to answer the second question, I look at definitions of narrative, distinguishing narrative from non-narrative texts. I highlight the linguistic properties of narrative and illustrate modes of analysis, paying close attention to both the structural properties of the text and its subtle linguistic nuances. I guide the reader through a detailed analysis of a short narrative text. I show how linguistics and sociology interplay at the level of a text.
Coronary Thermodilution to Assess Flow Reserve
Authors: Pijls Nico H.J. , De Bruyne Bernard , Smith Leif , Aarnoudse Wilbert , Barbato Emanuele , Bartunek Jozef , Bech G. Jan Willem , Van De Vosse Frans
Published: July 2002

Background

—

Guide wire–based simultaneous measurement of fractional flow reserve (FFR) and coronary flow reserve (CFR) is important to understand microvascular disease of the heart. The aim of this study was to investigate the feasibility of simultaneous measurement of FFR and CFR by one pressure-temperature sensor-tipped guide wire with the use of coronary thermodilution and to compare CFR by thermodilution (CFR

thermo

) with simultaneously measured Doppler CFR (CFR

Doppl

).

Methods and Results

—

In 103 coronary arteries in 50 patients, a pressure-temperature sensor-tipped 0.014-inch floppy guide wire and a 0.014-inch Doppler guide wire were introduced. Both normal vessels and a wide range of stenotic vessels were included. With 3 mL of saline at room temperature used as an indicator, by hand-injection, thermodilution curves in the coronary artery were obtained in triplicate, both at baseline and at intravenous adenosine-induced maximum hyperemia. After adequate curve-fitting, CFR

thermo

was calculated from the ratio of inverse mean transit times and compared with CFR

Doppl

calculated by velocities at hyperemia and baseline. Adequate sets of thermodilution curves and corresponding CFR

thermo

could be obtained in 87% of the arteries versus 91% for Doppler CFR and 100% for FFR. CFR

thermo

correlated fairly well to CFR

Doppl

(CFR

thermo

=0.84 CFR

Doppl

+0.17;
r
=0.80;
P
<0.001), although individual differences of >20% between both indexes were seen in a quarter of all arteries.

Conclusions

—

This study shows the feasibility of simultaneous measurement of FFR (by coronary pressure) and CFR (by coronary thermodilution) in humans by one single guide wire in a practical and straightforward way and will facilitate assessment of microvascular disease.
Atorvastatin Inhibits Hypercholesterolemia-Induced Cellular Proliferation and Bone Matrix Production in the Rabbit Aortic Valve
Authors: Rajamannan Nalini M. , Subramaniam Malayannan , Springett Margaret , Sebo Thomas C. , Niekrasz Marek , McConnell Joseph P. , Singh Ravinder J. , Stone Neil J. , Bonow Robert O. , Spelsberg Thomas C.
Published: July 2002

Background
—

Despite the common occurrence of aortic stenosis, the cellular causes of the disorder are unknown, in part because of the absence of experimental models. We hypothesized that atherosclerosis and early bone matrix expression in the aortic valve occurs secondary to experimental hypercholesterolemia and that treatment with atorvastatin modifies this transformation.

Methods and Results
—

To test this hypothesis, we developed an experimental hypercholesterolemic rabbit model. New Zealand White rabbits (n=48) were studied: group 1 (n=16), normal diet; group 2 (n=16), 1% (wt/wt) cholesterol diet; and group 3 (n=16), 1% (wt/wt) cholesterol diet plus atorvastatin (3 mg/kg per day). The aortic valves were examined with hematoxylin and eosin stain, Masson trichrome, macrophage (RAM 11), proliferation cell nuclear antigen (PCNA), and osteopontin immunostains. Cholesterol and highly sensitive C-reactive protein (hsCRP) serum levels were obtained by standard assays. Computerized morphometry and digital image analysis were performed for quantifying PCNA (% area). Electron microscopy and immunogold labeling were performed for osteopontin. Semiquantitative RT-PCR was performed for the osteoblast bone markers [alkaline phosphatase, osteopontin, and osteoblast lineage-specific transcription factor (
Cbfa-1
)]. There was an increase in cholesterol, hsCRP, PCNA, RAM 11, and osteopontin and osteoblast gene markers (alkaline phosphatase, osteopontin, and
Cbfa-1
) in the cholesterol-fed rabbits compared with control rabbits. All markers except hsCRP were reduced by atorvastatin.

Conclusions
—

These findings of increased macrophages, PCNA levels, and bone matrix proteins in the aortic valve during experimental hypercholesterolemia provide evidence of a proliferative atherosclerosis–like process in the aortic valve associated with the transformation to an osteoblast-like phenotype that is inhibited by atorvastatin.