bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Plant Populations Purge Their Genetic Load? Effects of Population Size and Mating History on Inbreeding Depression
Authors: Byers D. L. , Waller D. M.
Published: July 2002

▪ Abstract  Inbreeding depression critically influences both mating system evolution and the persistence of small populations prone to accumulate mutations. Under some circumstances, however, inbreeding will tend to purge populations of enough deleterious recessive mutations to reduce inbreeding depression (ID). The extent of purging depends on many population and genetic factors, making it impossible to make universal predictions. We review 52 studies that compare levels of ID among species, populations, and lineages inferred to differ in inbreeding history. Fourteen of 34 studies comparing ID among populations and species found significant evidence for purging. Within populations, many studies report among-family variation in ID, and 6 of 18 studies found evidence for purging among lineages. Regression analyses suggest that purging is most likely to ameliorate ID for early traits (6 studies), but these declines are typically modest (5–10%). Meta-analyses of results from 45 populations in 11 studies reveal no significant overall evidence for purging, but rather the opposite tendency, for more selfing populations to experience higher ID for early traits. The likelihood of finding purging does not vary systematically with experimental design or whether early or late traits are considered. Perennials are somewhat less likely to show purging than annuals (2 of 10 vs. 7 of 14). We conclude that although these results doubtless reflect variation in population and genetic parameters, they also suggest that purging is an inconsistent force within populations. Such results also imply that attempts to deliberately reduce the load via inbreeding in captive rearing programs may be misguided. Future studies should examine male and female fitness traits over the entire life cycle, estimate mating histories at all levels (i.e. population and families within populations), report data necessary for meta-analysis, and statistically test for purging of genetic loads.
Chemical Detection of Natural Enemies by Arthropods: An Ecological Perspective
Authors: Dicke Marcel , Grostal Paul
Published: July 2002

▪ Abstract  Food webs are overlaid with infochemical webs that mediate direct and indirect interactions. The infochemicals may result in shifts in trait values, which affect the strength of species interactions. As a consequence, population dynamics and evolutionary changes can be affected. Chemical information can mediate the interactions between animals and their resources, competitors and enemies. Of all chemical information gathered by animals, cues about predation risk are of special significance because predation risk usually has important and immediate consequences on fitness. In this paper we selectively review the role of chemical information in enemy avoidance by arthropods. Arthropods not only constitute important components of food webs, being the largest group in numbers and species diversity; they also make excellent models for ecological studies. We discuss the evidence, the key mechanisms, and the trade-offs involved in chemical detection of enemies by potential arthropod prey. Further, we address the variation in prey responses and the evidence for learning in avoiding enemies by arthropods. Finally, we identify and prioritize major questions to be tackled by future studies.
POPULATION GENETIC PERSPECTIVES ON THE EVOLUTION OF RECOMBINATION
Authors: Feldman Marcus W. , Otto Sarah P. , Christiansen Freddy B.
Published: July 2002

It is not generally realized that genetics has finally solved the age-old problem of the reason for the existence (i.e. the function) of sexuality and sex, and that only geneticists can properly answer the question, “Is sex necessary?”

▪ Abstract  Optimality arguments and modifier theory are reviewed as paradigms for the study of the evolution of recombination. Optimality criteria (such as maximization of mean fitness) may agree with results from models developed in terms of the evolution of recombination at modifier loci. Modifier models demonstrate, however, that equilibrium mean fitness can decrease during the evolution of recombination rates and is not always maximized. Therefore, optimality arguments do not successfully predict the conditions under which increased or decreased recombination will evolve. The results from modifier models indicate that decreased recombination rates are usually favored when the population is initially near a polymorphic equilibrium with linkage disequilibrium. When the population is subject to directional selection or to deleterious mutations, increased recombination may be favored under certain conditions, provided that there is negative epistasis among alleles.
CONTROL OF TRANSCRIPTION TERMINATION IN PROKARYOTES
Authors: Henkin Tina M.
Published: July 2002

▪ Abstract  A growing number of genetic systems have been shown to be controlled at the level of premature termination of transcription. Genes in this class contain transcription termination signals in the region upstream of the coding sequence. The activity of these regulatory termination signals is controlled through a variety of mechanisms. These include modification of RNA polymerase to a terminator-resistant, or terminator-prone form, and alterations in the structure of the nascent transcript, to determine whether the stem-loop structure of an intrinsic terminator or an alternate antiterminator is formed. Structural alterations in the transcript can be controlled by the kinetics of translation of the RNA, by binding of specific regulatory proteins, and by mRNA-tRNA interactions. This review describes a number of variations on the termination control theme that have been uncovered in prokaryotes.
ELECTRICAL CHARACTERIZATION OF THIN-FILM ELECTROLUMINESCENT DEVICES
Authors: Wager J. F. , Keir P. D.
Published: July 2002

▪ Abstract  Electrical characterization methods for the analysis of alternating current thin-film electroluminescent (ACTFEL) devices are reviewed. Particular emphasis is devoted to electrical characterization techniques because ACTFEL devices are electro-optic display devices whose performance is to a large extent determined by their electrical properties. A systematic procedure for ACTFEL electrical assessment is described. The utility of transient charge, voltage, current, and phosphor field analysis is explained. Steady-state electrical characterization methods discussed in this review include charge-voltage (Q-V), capacitance-voltage (C-V), internal charge-phosphor field (Q-Fp), and maximum charge-maximum applied voltage (Qmax-Vmax) analysis. These electrical characterization methods are illustrated by reviewing relevant results obtained from the analysis of evaporated ZnS:Mn and atomic layer epitaxy (ALE) SrS:Ce ACTFEL devices.
COMBINATORIAL MATERIALS SYNTHESIS AND SCREENING: An Integrated Materials Chip Approach to Discovery and Optimization of Functional Materials
Authors: Xiang X.-D.
Published: July 2002

▪ Abstract  Combinatorial materials synthesis methods and high throughput evaluation techniques have been developed to accelerate the process of materials discovery and optimization. Analogous to integrated circuit chips, integrated materials chips containing thousands, possibly millions, of different compounds/materials, often in the form of high-quality epitaxial thin film can be fabricated and screened for interesting physical or chemical properties. Microspot X-ray methods, various optical measurement techniques, and a novel evanescent microwave microscope have been used to characterize the structural, optical, magnetic, and electrical properties of samples on materials chips. These techniques are routinely used to discover and optimize luminescent, ferroelectric, dielectric, and magnetic materials.
ETIOPATHOGENESIS AND TREATMENT OF PSYCHOSIS
Authors: Crow T. J. , Harrington C. A.
Published: July 2002

▪ Abstract  Psychotic illnesses (schizophrenia and schizoaffective and affective psychosis) have a lifetime prevalence of 2–3% and probably occur at a similar rate in all human societies. No etiologically significant environmental precipitants have been identified, and this suggests that these diseases are primarily genetic. Brain studies reveal that in schizophrenic patients, development of cerebral asymmetry is arrested, which may be associated with a small reduction in cortical mass. Episodes of illness can be ameliorated by dopamine (in particular D2) antagonists, drugs that are antipsychotic rather than merely antischizophrenic. The discovery of at least five dopamine receptor subtypes and their genes paves the way for new approaches to treatment. However, whether psychotic patients undergo a primary disturbance of dopaminergic transmission remains unclear.
THE COURSE AND TREATMENT OF LUPUS NEPHRITIS
Authors: Appel, M.D Gerald B. , Valeri, M.D Anthony
Published: July 2002

▪ Abstract  Renal involvement by systemic lupus is variable; some patients have minimal clinical and histologic involvement, whereas others have fulminant renal failure and severe proliferative renal lesions on biopsy. The World Health Organization (WHO) classification has greatly aided in the study of lupus nephritis. This classification defines six major patterns of renal involvement, each with characteristic clinical correlates and a typical course and prognosis. Transformations from one pattern of lupus nephritis to another may occur, and there may also be prominent involvement of the tubulointerstitial compartment and vasculature. Treatment of the renal lesions may be directed at the individual class of lupus nephritis. Thus patients with mesangial involvement (WHO Class II) do not require therapy directed at their kidney lesions. Many patients with biopsies showing focal proliferative disease (WHO Class III) and all patients whose biopsies show diffuse proliferative lesions (WHO Class IV) require vigorous treatment, which has included high-dose daily and alternate-day corticosteroids, azathioprine, i.v. pulse methylprednisolone, plasmapheresis, total lymphoid irradiation, cyclosporine, and oral and i.v. cyclophosphamide. Controlled trials have yielded reasonable evidence for the safety and efficacy of some treatments, whereas others have been used only in uncontrolled studies. When used judiciously, such vigorous therapy can improve the renal survival of patients with severe lupus nephritis.
FULMINANT HEPATIC FAILURE: Pathophysiology, Treatment, and Survival
Authors: Atillasoy, M.D E. , Berk, M.D P. D.
Published: July 2002

▪ Abstract  Fulminant hepatic failure is characterized by severe metabolic derangements, neurologic complications and, ultimately, multiorgan failure. In the past three decades, improved intensive care has increased mean survival from 15% to 50% in certain patient groups by providing metabolic support and management of specific, frequent, and potentially fatal complications. However, outcome remains highly dependent on etiology. While intensive care is sufficient therapy in some patients (Group I), those with irreparable hepatic damage (Group III) can only survive if transplanted. In intermediate cases (Group II), the liver retains the potential to regenerate if the patient receives hepatic functional support. Major areas of current research in this field include development of hepatic support devices, strategies to accelerate and maximize hepatic regeneration, and criteria for accurate prognostic classification of patients.
ANTIMICROBIAL-RESISTANT PATHOGENS IN THE 1990s
Authors: Jacoby, M.D George A.
Published: July 2002

▪ Abstract  Streptococcus pneumoniae, Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, and Klebsiella pneumoniae have become increasingly resistant to antimicrobial agents. This chapter reviews the epidemiology of this resistance, its detection in the laboratory, the mechanisms of resistance, and the options for therapy and infection control.
CLINICAL IMPLICATIONS OF THE p53 GENE
Authors: Sidransky, M.D David , Hollstein, Ph.D Monica
Published: July 2002

▪ Abstract  The capacity for malignant growth is acquired by the stepwise accumulation of defects in specific genes regulating cell growth and tissue homeostasis. Although several hundred genes are known to control growth, molecular genetic studies in cancer show that few of these are consistently involved in the natural history of human cancer, and those typically in only certain types of malignancy. Prospects for development of molecular-based diagnostic and therapeutic strategies with widespread application did not look promising, until it was realized that the p53 tumor suppressor gene was defective in approximately half of all malignancies. This discovery generated research efforts of unparalleled intensity to determine how p53 functions at the molecular level, and how to apply this knowledge to clinical ends.
APOPTOSIS AND DISEASE: Regulation and Clinical Relevance of Programmed Cell Death
Authors: M. Rudin, MD, PhD Charles , B. Thompson, MD Craig
Published: July 2002

▪ Abstract  Regulation of the homeostatic balance between cell proliferation and cell death is essential for development and maintenance of multicellular organisms. Physiologic, or programmed, cell death is dependent on a genetically encoded and evolutionarily conserved pathway that induces a form of cellular suicide known as apoptosis. In the past decade, it has become clear that the regulatory mechanisms controlling programmed cell death are as fundamental, and as complex, as those regulating cell proliferation. Perturbation of the signaling cascades regulating apoptosis, whether by extracellular triggers, acquired or germline genetic mutations, or viral mimicry of signaling molecules, can result in a wide variety of human diseases. Analysis of these regulatory pathways has led to a better understanding of the etiology and pathogenesis of many human diseases, notably cancers, infectious diseases including AIDS, autoimmune diseases, and neurodegenerative/neurodevelopmental diseases. Our understanding of the regulation of programmed cell death in health and disease is far from complete, and the challenge of converting that understanding into new therapeutic modalities has only begun to be approached.
Adjuvant Therapy for Breast Cancer
Authors: Hortobagyi G.
Published: July 2002

Substantial progress has been made in the diagnosis and management of primary breast cancer over the past three decades. As a result, mortality related to this disease has been decreasing gradually for several years, treatment has become more effective, and side effects and complications related to treatment have decreased. In this report, we review the state of adjuvant therapy for breast cancer.
Risk-Adjusted Surgical Outcomes
Authors: Daley Jennifer , Henderson William G. , Khuri Shukri F.
Published: July 2002

▪ Abstract  Measures of risk-adjusted outcome are particularly suited for the assessment of the quality of surgical care. The reliability of measures of quality that use surgical outcomes is enhanced by prospective data acquisition and should be adjusted for the preoperative severity of illness. Such measures should be based only on reliable and validated data, and they should apply state-of-the-art analytical methods. The risk-adjusted postoperative mortality rate is useful as a quality measure only in specialties and operations expected to have a high rate of postoperative deaths. Risk-adjusted complications are more common but are limited as a comparative measure of quality by a lack of uniform definitions and data collection mechanisms. In specialties in which the expected postoperative mortality is low, risk-adjusted functional outcomes are promising measures for the assessment of the quality of surgical care. Measures of cost and patient satisfaction should also be incorporated in systems designed to measure the quality and cost-effectiveness of surgical care.
Will the Pig Solve the Transplantation Backlog?
Authors: Cooper David K. C. , Gollackner Bernd , Sachs David H.
Published: July 2002

▪ Abstract  The increasing shortage of human cadaveric organs for purposes of transplantation has become the critical limiting factor in the number of transplants performed each year. Some of this deficit is being met by the use of organs or partial organs from living donors, but this source is insufficient. Xenotransplantation—the transplantation of organs between species, namely from the pig to human—could provide a solution if immunologic and other associated problems could be solved. When a pig organ is transplanted into a primate, hyperacute rejection, induced by anti-pig antibody and mediated by complement and the coagulation system, develops rapidly. This immediate problem can now be overcome, but the return or persistence of anti-pig antibody leads to a delayed form of humoral rejection, acute humoral xenograft rejection, which leads to destruction of the organ within days or weeks. We review the various approaches being investigated to overcome this barrier. Whether they will also prevent subsequent acute cellular rejection remains unknown. Brief mention is made of the potential physiologic incompatibilities between pig and human organs, as well as the microbiologic safety aspects of xenotransplantation. Finally, the question of patient and societal acceptance of xenotransplantation is discussed.
ANAEROBIC GROWTH OF A “STRICT AEROBE” (BACILLUS SUBTILIS)
Authors: Nakano Michiko M. , Zuber Peter
Published: July 2002

▪ Abstract  There was a long-held belief that the gram-positive soil bacterium Bacillus subtilis is a strict aerobe. But recent studies have shown that B. subtilis will grow anaerobically, either by using nitrate or nitrite as a terminal electron acceptor, or by fermentation. How B. subtilis alters its metabolic activity according to the availability of oxygen and alternative electron acceptors is but one focus of study. A two-component signal transduction system composed of a sensor kinase, ResE, and a response regulator, ResD, occupies an early stage in the regulatory pathway governing anaerobic respiration. One of the essential roles of ResD and ResE in anaerobic gene regulation is induction of fnr transcription upon oxygen limitation. FNR is a transcriptional activator for anaerobically induced genes, including those for respiratory nitrate reductase, narGHJI. B. subtilis has two distinct nitrate reductases, one for the assimilation of nitrate nitrogen and the other for nitrate respiration. In contrast, one nitrite reductase functions both in nitrite nitrogen assimilation and nitrite respiration. Unlike many anaerobes, which use pyruvate formate lyase, B. subtilis can carry out fermentation in the absence of external electron acceptors wherein pyruvate dehydrogenase is utilized to metabolize pyruvate.
COOPERATIVE ORGANIZATION OF BACTERIAL COLONIES: From Genotype to Morphotype
Authors: Ben-Jacob Eshel , Cohen Inon , Gutnick David L.
Published: July 2002

▪ Abstract  In nature, bacteria must often cope with difficult environmental conditions. To do so they have developed sophisticated cooperative behavior and intricate communication pathways. Utilizing these elements, motile microbial colonies frequently develop complex patterns in response to adverse growth conditions on hard surfaces under conditions of energy limitation. We employ the term morphotype to refer to specific properties of colonial development. The morphologies we discuss include a tip-splitting (T) morphotype, chiral (C) morphotype, and vortex (V) morphotype. A generic modeling approach was developed by combining a detailed study of the cellular behavior and dynamics during colonial development and invoking concepts derived from the study of pattern formation in nonliving systems. Analysis of patterning behavior of the models suggests bacterial processes whereby communication leads to self-organization by using cooperative cellular interactions. New features emerging from the model include various modes of cell-cell signaling, such as long-range chemorepulsion, short-range chemoattraction, and, in the case of the V morphotype, rotational chemotaxis. In this regard, pattern formation in microorganisms can be viewed as the result of the exchange of information between the micro-level (the individual cells) and the macro-level (the colony).
Role of Cytotoxic T Lymphocytes in Epstein-Barr Virus-Associated Diseases
Authors: Khanna Rajiv , Burrows Scott R.
Published: July 2002

▪ Abstract  Adaptation of persistent infection within the cells of the immune system is a unique characteristic of gamma herpes viruses. A classic example of this is Epstein-Barr virus (EBV), which may have co-evolved with Homo sapiens over millions of years, thus achieving a balance between viral persistence and immune control. In this review, we present an overview of virus and the host immune system interactions that regulate the life-long host-virus relationship in healthy virus carriers and EBV-associated diseases. Extensive analysis of cytotoxic T lymphocyte–mediated immune responses in healthy virus carriers has revealed unique mechanisms used by EBV to maintain a benign persistent state in vivo. On the other hand, this relationship in EBV-associated diseases favors the escape of the virus from the hostile effects of the immune response. This escape is achieved by either down-regulating the expression of highly immunogenic antigens of the virus or by direct modulation of the host cytotoxic T lymphocyte response by virus-encoded proteins.
Molecular Genetics of Circadian Rhythms in Mammals
Authors: King David P. , Takahashi Joseph S.
Published: July 2002

Recent gene discovery approaches have led to a new era in our understanding of the molecular basis of circadian oscillators in animals. A conserved set of genes in Drosophila and mammals (Clock, Bmal1, Period, and Timeless) provide a molecular framework for the circadian mechanism. These genes define a transcription-translation–based negative autoregulatory feedback loop that comprises the core elements generating circadian rhythmicity. This circadian core provides a focal point for understanding how circadian rhythms arise, how environmental inputs entrain the oscillatory system, and how the circadian system regulates its outputs. The addition of molecular genetic approaches to the existing physiological understanding of the mammalian circadian system provides new opportunities for understanding this basic life process.
Paraneoplastic Neurologic Disease Antigens: RNA-Binding Proteins and Signaling Proteins in Neuronal Degeneration
Authors: Musunuru Kiran , Darnell Robert B.
Published: July 2002

▪ Abstract  Studies of the disorders known as paraneoplastic neurologic degenerations exemplify the successful application of modern molecular biological techniques to diseases, yielding, even for these extremely rare disorders, wide-ranging insight into basic neurobiology, tumor immunity, and autoimmune neurologic disease. Immune responses to paraneoplastic neurologic degeneration antigens, also called onconeural antigens, have been exploited to clone and characterize a number of neuron-specific proteins, including several RNA-binding proteins and new kinds of signaling molecules. The biology and functions of these proteins are reviewed, and a model in which their functions are related to the pathogenesis of autoimmune neurologic disease is discussed.
OSCILLATIONS OF ATMOSPHERIC NEUTRINOS
Authors: Jung C. K. , Kajita T. , Mann T. , McGrew C.
Published: July 2002

▪ Abstract  The observation of muon flavor disappearance in the atmospheric neutrino flux provides compelling evidence for neutrino flavor oscillations and, by implication, for nonzero neutrino rest mass. We review recent results from Super-Kamiokande and other underground atmospheric neutrino experiments. These results, along with oscillation limits from reactor experiments, are evaluated in the context of neutrino three-state mixing. A unifying picture with νμ to ντ oscillation as the dominant mode emerges; however, certain ambiguities remain. Future directions for further experimentation are discussed.
TRANSGENIC MICE IN THE ANALYSIS OF METABOLIC REGULATION
Authors: Bosch Fatima , Pujol Anna , Valera Alfons
Published: July 2002

▪ Abstract  In normal animals, the extracellular concentration of glucose is maintained within a very narrow range by the matching of glucose flux into and out of the extracellular space through the tightly coordinated secretion of insulin and glucagon. Functional alterations in β-cells, liver, or skeletal muscle and adipose tissue may disrupt glucose homeostasis and lead to the development of non–insulin-dependent diabetes mellitus (type 2 diabetes). This review outlines the contribution of these organs and tissues to the control of glucose homeostasis. We discuss new insights obtained through studies of transgenic mice that overexpress or show decreased expression of putative key genes in the regulation of pancreatic β-cell function, in the control of hepatic glucose uptake and output, and in the regulation of glucose uptake and utilization by skeletal muscle and adipose tissue.
ROLE OF ORGANIC CATION TRANSPORTERS IN DRUG ABSORPTION AND ELIMINATION
Authors: Zhang Lei , Brett Claire M. , Giacomini Kathleen M.
Published: July 2002

▪ Abstract  Organic cation transporters are critical in drug absorption, targeting, and disposition. It has become increasingly clear that multiple mechanisms are involved in organic cation transport in the key tissues responsible for drug absorption and disposition: the kidney, liver, and intestine. In this review, we discuss current models of transepithelial flux of organic cations in these three tissues. Particular emphasis is placed on the more recent molecular studies that have paved the way for a more complete understanding of the physiological and pharmacological roles of the organic cation transporters. Such information is essential in predicting pharmacokinetics and pharmacodynamics and in the design and development of cationic drugs.
Signal Transduction by Cell Adhesion Receptors and the Cytoskeleton: Functions of Integrins, Cadherins, Selectins, and Immunoglobulin-Superfamily Members
Authors: Juliano R. L.
Published: July 2002

Cellular interactions with the extracellular matrix and with neighboring cells profoundly influence a variety of signaling events including those involved in mitogenesis, survival, and differentiation. Recent advances have provided insights into mechanisms underlying the ability of integrins, cadherins, selectins, and other cell adhesion molecules to regulate signal transduction cascades. These mechanisms often involve the ability of cell adhesion molecules to initiate the formation of organized structures or scaffolds that permit the efficient flow of information in signaling pathways.
EXPERIMENTS ON THE DYNAMICS OF MOLECULAR PROCESSES: A Chronicle of Fifty Years
Authors: Boato Giovanni , Volpi Gian Gualberto
Published: July 2002

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▪ Abstract  This paper reviews the way in which, in the Italy of the years immediately after World War II, interest in the dynamics of molecular processes was awakened. The narrative begins with the work of a small number of chemists and physicists who, in the initial stage, interacted closely. In the course of the years, their interests diverged and younger people joined the newly formed groups. Even now, after half a century, a common approach can still to be seen regarding how to attack problems and perform experiments. Experimental work is discussed, bringing out the common viewpoint of fields as diverse as mass spectrometry, isotope effects, chemical kinetics, molecular beams, molecule-molecule interactions, molecule-ion interactions, molecule-surface interactions, and plasma chemistry.
CROSSED-BEAM STUDIES OF REACTION DYNAMICS
Authors: Casavecchia Piergiorgio , Balucani Nadia , Volpi Gian Gualberto
Published: July 2002

▪ Abstract  This article reviews recent progress in our understanding of gas-phase neutral reaction dynamics as made possible by improvements in the crossed molecular beam scattering technique for measuring reactive differential cross sections. A selection of crossed-beam studies on systems that play a fundamental role in our basic understanding of reaction phenomena are discussed to illustrate the capabilities of the experimental method. The examples include benchmark atom-diatom abstraction and insertion reactions, and four-atom radical reactions for which state-to-state, state-resolved, or state-averaged differential cross sections have recently been measured. The results are discussed in the light of the latest related theoretical developments regarding the treatment of potential energy surfaces and the dynamics of the systems. Recent results on crossed-beam studies of chemically relevant reactions of carbon, nitrogen, and oxygen atoms are also reviewed, and the latest developments in the technique are noted.
CHEMICAL APPLICATIONS OF NEUTRON SCATTERING
Authors: Trouw F. R. , Price D. L.
Published: July 2002

▪ Abstract  Neutron scattering represents a versatile technique for chemists, as it explores the structure and dynamics of materials at the atomic scale. This review gives an outline of the neutron scattering formalism and describes diffraction and inelastic and quasielastic scattering techniques. Applications to chemistry are illustrated by examples from recent work on crystalline and liquid organic materials, including heterogeneous systems, bulk polymers and polymer solutions. There is particular emphasis on systems where hydrogen bonding plays a significant role. With more powerful sources and improved instrumentation in prospect, there is considerable potential for future extension of these methods to increasingly complex materials.
Effective Interactions Between Electric Double Layers
Authors: Hansen Jean-Pierre , Löwen Hartmut
Published: July 2002

This review summarizes and assesses recent theoretical and experimental advances, with special emphasis on the effective interaction between charge-stabilized colloids, in the bulk or in confined geometries, and on the ambiguities of defining an effective charge of the colloidal particles. Some consideration is given to the often neglected discrete solvent effects.
REGULATION OF NATRIURETIC PEPTIDE SECRETION BY THE HEART
Authors: Thibault G. , Amiri F. , Garcia R.
Published: July 2002

▪ Abstract  Secreted by the heart, more specifically by atrial cardiomyocytes under normal conditions but also by ventricular myocytes during cardiac hypertrophy, natriuretic peptides are now considered important hormones in the control of blood pressure and salt and water excretion. Studies on natriuretic peptide secretagogues and their mechanisms of action have been complicated by hemodynamic changes and contractions to which the atria are constantly subjected. It now appears that atrial stretch through mechano-sensitive ion channels, adrenergic stimulation via α1A-adrenergic receptors, and endothelin via its ETA receptor subtype are major triggering agents of natriuretic peptide release. With several other stimuli, such as angiotensin II and β-adrenergic agents, modulation of natriuretic peptide release appears to be linked to local generation of prostaglandins. In all cases, intracellular calcium homeostasis, controlled by several ion channels, is considered a key element in the regulation of natriuretic peptide secretion.
RECONSTITUTION OF REGULATED EXOCYTOSIS IN CELL-FREE SYSTEMS: A Critical Appraisal
Authors: Avery Julia , Jahn Reinhard , Edwardson J. Michael
Published: July 2002

▪ Abstract  Regulated exocytosis involves the tightly controlled fusion of a transport vesicle with the plasma membrane. It includes processes as diverse as the release of neurotransmitters from presynaptic nerve endings and the sperm-triggered deposition of a barrier preventing polyspermy in oocytes. Cell-free model systems have been developed for studying the biochemical events underlying exocytosis. They range from semi-intact permeabilized cells to the reconstitution of membrane fusion from isolated secretory vesicles and their target plasma membranes. Interest in such cell-free systems has recently been reinvigorated by new evidence suggesting that membrane fusion is mediated by a basic mechanism common to all intracellular fusion events. In this chapter, we review some of the literature in the light of these new developments and attempt to provide a critical discussion of the strengths and limitations of the various cell-free systems.
LONG-TERM POTENTIATION AND LEARNING
Authors: Martinez Joe L. , Derrick Brian E.
Published: July 2002

▪ Abstract  Long-term potentiation (LTP), a relatively long-lived increase in synaptic strength, remains the most popular model for the cellular process that may underlie information storage within neural systems. The strongest arguments for a role of LTP in memory are theoretical and involve Hebb's Postulate, Marr's theory of hippocampal function, and neural network theory. Considering LTP research as a whole, few studies have addressed the essential question: Is LTP a process involved in learning and memory? The present manuscript reviews research that attempts to link LTP with learning and memory, focusing on studies utilizing electrophysiological, pharmacological, and molecular biological methodologies. Most evidence firmly supports a role for LTP in learning memory. However, an unequivocal experimental demonstration of a contribution of LTP to memory is hampered by our lack of knowledge of the biological basis of memory and of the ways in which memories are represented in ensembles of neurons, the existence of a variety of cellular forms of LTP, and the likely resistance of distributed memory stores to degradation by treatments that incompletely disrupt LTP.
WOMEN AND CAREER DEVELOPMENT: A Decade of Research
Authors: Phillips Susan D. , Imhoff Anne R.
Published: July 2002

▪ Abstract  This chapter reviews the vocational experiences of women as they have been revealed in the literature during the past decade. The review considers primarily empirical literature; findings are sampled relative to women's self-concept development, readiness for vocational choices, actual choices made, work-force entry, experiences at work, and retirement. Suggestions are made regarding the next generation of research on women and career development.
HEALTH PSYCHOLOGY: Mapping Biobehavioral Contributions to Health and Illness
Authors: Baum Andrew , Posluszny Donna M.
Published: July 2002

▪ Abstract  Our evolving understanding of how psychosocial and behavioral factors affect health and disease processes has been marked by investigation of specific relationships and mechanisms underlying them. Stress and other emotional responses are components of complex interactions of genetic, physiological, behavioral, and environmental factors that affect the body's ability to remain or become healthy or to resist or overcome disease. Regulated by nervous, endocrine, and immune systems, and exerting powerful influence on other bodily systems and key health-relevant behaviors, stress and emotion appear to have important implications for the initiation or progression of cancer, HIV, cardiovascular disease, and other illnesses. Health-enhancing and health-impairing behaviors, including diet, exercise, tobacco use, and protection from the sun, can compromise or benefit health and are directed by a number of influences as well. Finally, health behaviors related to being ill or trying to avoid disease or its severest consequences are important. Seeking care and adhering to medical regimens and recommendations for disease surveillance allow for earlier identification of health threats and more effective treatment. Evidence that biobehavioral factors are linked to health in integrated, complex ways continues to mount, and knowledge of these influences has implications for medical outcomes and health care practice.
Health Psychology: Psychosocial and Biobehavioral Aspects of Chronic Disease Management
Authors: Schneiderman Neil , Antoni Michael H. , Saab Patrice G. , Ironson Gail
Published: July 2002

▪ Abstract  Psychosocial factors appear to impact upon the development and progression of such chronic diseases as coronary heart disease, cancer, and HIV/AIDS. Similarly, psychosocial interventions have been shown to improve the quality of life of patients with established disease and seem to influence biological processesthought to ameliorate disease progression. Small-scale studies are useful for specifying the conditions under which psychosocial factors may or may not impactquality of life, biological factors, and disease progression. They are also useful for informing us about the conditions under which psychosocial interventions can serve as adjuvants (e.g. adherence training) to medical treatments. Only large-scale clinical trials, however, can determine the extent to which these psychosocial interventions may impact morbidity and mortality.
Nitric Oxide Modulates Superoxide Release and Peroxynitrite Formation in Human Blood Vessels
Authors: Guzik Tomasz J. , West Nick E.J. , Pillai Ravi , Taggart David P. , Channon Keith M.
Published: July 2002

Nitric oxide and superoxide have important roles as vascular signaling molecules. Nitric oxide (NO) reacts rapidly with superoxide, producing peroxynitrite. The relative balance between these radicals has important implications for vascular pathophysiology in hypertension and other vascular disease states. However, the relationships between superoxide, NO, and peroxynitrite formation in human blood vessels remain unclear. Accordingly, we systematically measured NO, superoxide, and peroxynitrite production from human internal mammary arteries, radial arteries, and saphenous veins from 78 patients undergoing coronary bypass surgery. Basal superoxide release was detected in all vessels at similar levels. However, endothelial removal or nitric oxide synthase inhibition increased mean superoxide release, with a corresponding reduction in peroxynitrite formation. Conversely, NO donors and superoxide scavengers both reduced superoxide release, whereas only NO donors increased peroxynitrite formation. These changes were much larger in arteries that in veins, but there were striking correlations between superoxide production, NO bioavailability, and peroxynitrite formation between the vessel types. Our findings provide direct evidence for coordinated vascular signaling mediated by interactions between NO, superoxide, and peroxynitrite and have important implications for studies of the functional effects of these radicals in human blood vessels.
Two Coupled Motor Recovery Protocols Are Better Than One
Authors: Cauraugh James H. , Kim Sangbum
Published: July 2002

Background and Purpose

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Overcoming chronic hemiparesis from a cerebrovascular accident (CVA) can be challenging for many patients, especially after the first 12 months after the CVA. With the use of established motor control theories, the present study investigated electromyogram (EMG)-triggered neuromuscular stimulation and bilateral coordination training.

Methods

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Twenty-five CVA subjects volunteered to participate in this motor recovery protocol study. Subjects were randomly assigned to 1 of 3 groups: (1) coupled protocol of EMG-triggered stimulation and bilateral movement (n=10); (2) EMG-triggered stimulation and unilateral movement (n=10); or (3) control (n=5). All participants completed 6 hours of rehabilitation during a 2-week period according to group assignments. Motor capabilities of the wrist and fingers were evaluated on the basis of 3 categories of motor tasks in a pretest-posttest control group design.

Results

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Significant findings for the (1) number of blocks moved in a functional task, (2) chronometric reaction times to initiate movements, and (3) sustained muscle contraction capability all favored the coupled bilateral movement training and EMG-triggered neuromuscular stimulation protocol group. In addition, the unilateral movement/stimulation group exceeded the control group in the number of blocks moved and rapid onset of muscle contractions.

Conclusions

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This new evidence is convincing in that subjects in the coupled protocol group were able to demonstrate enhanced voluntary motor control across 3 categories of tasks. Chronic hemiparesis decreased considerably in the wrist and fingers as CVA patients expanded their motor repertoire.
Policy Learning in Embedded Negotiations: Explaining EU Electricity Liberalization
Authors: Eising Rainer
Published: July 2002

Taking the example of the liberalization of the electricity supply industy, I analyze member-state negotiations in the European Union (EU). Confronting central tenets of the intergovernmental approach, I suggest that member-state executives act within the limits of bounded rationality and do not always hold clear and fixed preferences. I focus on the large member states Germany, France, and the United Kingdom and identify four institutional mechanisms that support outcomes above the least common denominator: (1) the role of norms that constrain strategic action and frame the negotiations, (2) the empowerment of supranational actors, (3) the decision routines of the Council of the European Union that provide standardized mechanisms for resolving conflicts and induce policy learning and preference changes, and (4) the vertical differentiation within the Council system that can unblock issue-specific controversies. Even if as a result of these techniques EU legal acts contain several flexibilization elements, they can trigger behavioral changes that clearly surpass their regulatory content.
Political Competition and Electoral Fraud: A Latin American Case Study
Authors: Molina Iván , Lehoucq Fabrice Edouard
Published: July 2002

Legal petitions to nullify electoral results comprise a rich source for studying electoral fraud. During a fifty-year period in Costa Rica, parties submitted 120 petitions to Congress, containing more than 1,200 charges of fraud. The petitions reveal that between 1901 and 1938, more than half of such accusations took place in the country's peripheral provinces, where roughly 20 percent of voters lived. They also show that institutional changes helped to shape the nature, frequency, and magnitude of fraud. By the 1940s, the polarization of political competition was accompanied by a geographical redistribution of fraud to the central provinces of the republic, where most of the electorate resided.
Scrambling and Last Resort
Authors: Bošković Željko , Takahashi Daiko
Published: July 2002

Under the standard analysis (e.g., Fukui 1993, Saito 1985, 1992), scrambling in Japanese raises a serious problem for the last resort view of Move α, since it is considered to involve optional overt movement that has no driving force. In this article we propose a new analysis of scrambling that puts scrambling in conformity with the Last Resort principle. We argue that scrambled elements are base-generated in their surface non-θ-positions and undergo obligatory LF movement to the position where they receive θ-roles, which we consider to be formal features capable of driving movement. We show that our LF analysis of scrambling is both conceptually and empirically superior to the standard optional overt movement analysis.
The Laryngeal Specifications of Fricatives
Authors: Vaux Bert
Published: July 2002

Phonologists have traditionally assumed that the unmarked laryngeal state of fricatives is to be unaspirated ([−spread glottis]). However, the data analyzed here, which are drawn from Armenian, Greek, Pali, Sanskrit, Spanish, and Thai, suggest that in their unmarked state voiceless fricatives are in fact [+spread glottis], whereas voiced fricatives are [−spread glottis].
Pipelines and Size Constraints
Authors: Reiter Ehud
Published: July 2002

Some types of documents need to meet size constraints, such as fitting into a limited number of pages. This can be a difficult constraint to enforce in a pipelined natural language generation (NLG) system, because size is mostly determined by content decisions, which usually are made at the beginning of the pipeline, but size cannot be accurately measured until the document has been completely processed by the NLG system. I present experimental data on the performance of single-solution pipeline, multiple-solution pipeline, and revision-based variants of the STOP system (which produces personalized smoking-cessation leaflets) in meeting a size constraint. This shows that a multiple-solution pipeline does much better than a single-solution pipeline, and that a revision-based system does best of all.
The Endogenous Modulation of IOR is Nasal-Temporal Asymmetric
Authors: Berger Andrea , Henik Avishai
Published: July 2002

Inhibition of return (IOR) refers to a reflexive mechanism mediated by phylogenetically primitive extrageniculate visuomotor pathways, which apparently serves to favor novel spatial locations by inhibiting those recently sampled. We demonstrate an asymmetry between temporal and nasal hemifields in the strategic modulation of IOR by endogenously controlled attention. Exogenous and endogenous precues were manipulated independently on each trial such that precues to initiate endogenous spatial orienting were presented after IOR had been activated by exogenous visual signals. Both types of precues manifested their characteristic effects on reaction time (RT) to detect subsequent targets: facilitation by endogenous precues, and IOR by exogenous precues. Under monocular viewing, an asymmetric interaction between these two mechanisms was observed. While endogenous allocation of attention to the nasal hemifield reduced IOR, no endogenous modulation of IOR was present in the temporal hemifield where the effects of the two types of precues were independent. These observations suggest a framework for understanding the neurobiology of automaticity and control—from an evolutionary perspective.
Deconvolution of Event-Related fMRI Responses in Fast-Rate Experimental Designs: Tracking Amplitude Variations
Authors: Hinrichs Hermann , Scholz Michael , Tempelmann Claus , Woldorff Martin G. , Dale Anders M. , Heinze Hans-Jochen
Published: July 2002

Recent developments towards event-related functional magnetic resonance imaging has greatly extended the range of experimental designs. If the events occur in rapid succession, the corresponding time-locked responses overlap significantly and need to be deconvolved in order to separate the contributions of different events. Here we present a deconvolution approach, which is especially aimed at the analysis of fMRI data where sequence- or context-related responses are expected. For this purpose, we make the assumption of a hemodynamic response function (HDR) with constant yet not predefined shape but with possibly variable amplitudes. This approach reduces the number of variables to be estimated but still keeps the solutions flexible with respect to the shape. Consequently, statistical efficiency is improved. Temporal variations of the HDR strength are directly indicated by the amplitudes derived by the algorithm. Both the estimation efficiency and statistical inference are further supported by an improved estimation of the noise covariance. Using synthesized data sets, both differently shaped HDRs and varying amplitude factors were correctly identified. The gain in statistical sensitivity led to improved ratios of false- and true-positive detection rates for synthetic activations in these data. In an event-related fMRI experiment with a human subject, different HDR amplitudes could be derived corresponding to stimulation at different visual stimulus contrasts. Finally, in a visual spatial attention experiment we obtained different fMRI response amplitudes depending on the sequences of attention conditions.