bluuebunny/crossref_metadata_2025 huggingface dataset:
Law and Clinical Research — From Rights to Regulation? An English Perspective
Authors: McHale J.V.
Published: July 2007

The last half century has been characterized by a growth in the regulation of clinical research nationally and internationally. Each area of research on human subjects has been the subject of a vast academic literature and extensive public policy debate, from issues of informed consent to that of regulatory structures. Professor Bernard Dickens has provided an outstanding contribution to this debate internationally through his many innovative and incisive papers in this area. This paper provides an English lawyer’s perspective upon the increasing regulation of clinical research practices and asks – does regulation equate with effective rights protection? From Nuremberg onwards, there has been concern to ensure that research practices are ethical and in accordance with legal principles. So, for example, there have been statements such as the Declaration of Helsinki, which was initially produced in 1964. In the European context in particular, notably influential statements have been the European Convention on Human Rights, which has been followed by the Council of Europe Convention on Human Rights and Biomedicine and, more recently, a Draft Additional Protocol on medical research.
Commentary: Social-Ethical Values Issues in the Political Public Square: Principles vs. Packages
Authors: Somerville Margaret
Published: July 2007

This article explores decision making about social-ethical values issues by members of the public in the context of the recent Canadian federal election, held in late June 2004. All of these issues are sensitive and controversial, and I hesitated to address them in an article that I dedicate, with respect and admiration, to my friend and fellow medical lawyer-ethicist, Bernard Dickens. Over the years Bernie and I have discussed, debated and disagreed on many of them. It speaks to his tolerance, reasonableness and wisdom that those occasions were for me always ones of learning and respect, colored by his inimitable sense of humor. I hope that Bernie feels that, in some small measure, this article reflects those same characteristics, ones that he has modeled for so many of us over the years of his distinguished career.
Weak action potential backpropagation is associated with high‐frequency axonal firing capability in principal neurons of the gerbil medial superior olive
Authors: Scott Luisa L. , Hage Travis A. , Golding Nace L.
Published: July 2007

Principal neurons of the medial superior olive (MSO) convey azimuthal sound localization cues through modulation of their rate of action potential firing. Previous intracellular studies in vitro have shown that action potentials appear highly attenuated at the soma of MSO neurons, potentially reflecting specialized action potential initiation and/or a physically distant site of generation. To examine this more directly, we made dual patch‐clamp recordings from MSO principal neurons in gerbil brainstem slices. Using somatic and dendritic whole‐cell recordings, we show that graded action potentials at the soma are highly sensitive to the rate of rise of excitation and undergo strong attenuation in their backpropagation into the dendrites (length constant, 76 μm), particularly during strong dendritic excitation. Using paired somatic whole‐cell and axonal loose‐patch recordings, we show that action potentials recorded in the axon at distances > 25 μm are all‐or‐none, and uniform in amplitude even when action potentials appear graded at the soma. This proximal zone corresponded to the start of myelination in the axon, as assessed with immunocytochemical staining for myelin basic protein in single‐labelled neurons. Finally, the axon was capable of sustaining remarkably high firing rates, with perfect entrainment occurring at frequencies of up to 1 kHz. Together, our findings show that action potential signalling in MSO principal neurons is highly secure, but shows a restricted invasion of the somatodendritic compartment of the cell. This restriction may be important for minimizing distortions in synaptic integration during the high frequencies of synaptic input encountered in the MSO.
Tomosyn negatively regulates both synaptic transmitter and neuropeptide release at the C. elegans neuromuscular junction
Authors: Gracheva Elena O. , Burdina Anna O. , Touroutine Denis , Berthelot‐Grosjean Martine , Parekh Hetal , Richmond Janet E.
Published: July 2007

The SNARE proteins, syntaxin, SNAP‐25 and synaptobrevin form a tertiary complex essential for vesicle fusion. Proteins that influence SNARE complex assembly are therefore likely to be important regulators of fusion events. In this study we have focused on tomosyn, a highly conserved, neuronally enriched, syntaxin‐binding protein that has been implicated in the regulation of vesicle exocytosis. To directly test the role of tomosyn in neurosecretion we analysed loss‐of‐function mutants in the single Caenorhabditis elegans tomosyn gene, tom‐1. These mutants exhibit enhanced synaptic transmission based on electrophysiological analysis of neuromuscular junction activity. This phenotype is the result of increased synaptic vesicle priming. In addition, we present evidence that tom‐1 mutants also exhibit enhanced peptide release from dense core vesicles. These results indicate that tomosyn negatively regulates secretion for both vesicle types, possibly through a common mechanism, interfering with SNARE complex formation, thereby inhibiting vesicle fusion.
Feeding microstructure in diet‐induced obesity susceptible versus resistant rats: central effects of urocortin 2
Authors: Cottone Pietro , Sabino Valentina , Nagy Tim R. , Coscina Donald V. , Zorrilla Eric P.
Published: July 2007

With one billion people overweight worldwide, the need to identify risk factors and treatments for obesity is urgent. The present study determined whether rats genetically prone to diet‐induced obesity (DIO) show preexisting differences in meal microstructure and are sensitive to central anorectic effects of corticotropin‐releasing factor type 2 (CRF2) receptor stimulation. Male, selectively bred DIO rats and their diet resistant (DR) counterparts (n= 9/genotype) were weaned onto low‐fat chow and compared as young adults for spontaneous or intracerebroventricular urocortin 2 administration‐induced (0, 0.3, 1, 3 μg) differences in ingestion. DIO rats were hyperphagic selectively at the dark cycle onset, showing shorter latencies to initiate feeding, faster returns to eating following meal completion, and a lower satiety ratio than DR rats. At other times, DIO rats had briefer postmeal intervals, but ate smaller and briefer meals, resulting in normal intake. DIO rats also ate faster than DR rats. Urocortin 2 was less potent in DIO rats, ineffective at the 0.3 μg dose, but produced CRF2 antagonist‐reversible anorexia at higher doses. Though heavier, chow‐maintained DIO rats were proportionately as or more lean than DR rats. Thus, DIO rats showed signs of a preexisting, heritable deficit in the maintenance of postmeal satiety and a reduced sensitivity to anorectic CRF2 agonist stimulation. The meal patterns of DIO rats temporally resemble human ‘snacking’ behaviour, which predicts adult obesity. Because central CRF2 stimulation retains full anorectic efficacy at higher doses in the DIO model, manipulating this neuropeptidergic system might yield new therapeutic approaches for diet‐induced obesity.
Histamine excites neurones in the human submucous plexus through activation of H1, H2, H3 and H4 receptors
Authors: Breunig Eva , Michel Klaus , Zeller Florian , Seidl Stefan , Weyhern Claus Werner Hann v. , Schemann Michael
Published: July 2007

Histamine is a major mast cell mediator of immunoneural signalling in the gut and mast cells play a role in the pathophysiology of functional and inflammatory bowel diseases. Histamine receptors are therefore promising drug targets to treat gut disorders. We aimed to study the so far unknown effect of histamine on neural activity in the human enteric nervous system (ENS) and to identify the pharmacology of histamine response. We used fast imaging techniques in combination with the potentiometric dye di‐8‐ANEPPS to monitor directly membrane potential changes and thereby neuronal excitability in the human submucous plexus from surgical specimens of 110 patients (2137 neurones, 273 ganglia). Local microejection of histamine resulted in action potential discharge in 37% of neurones. This excitatory effect was mimicked by the H1 agonist HTMT‐dimaleat, H2 agonist dimaprit, H3 agonist (R)‐(−)‐α‐methylhistamine and H4 agonist 4‐methylhistamine. The excitatory actions of the agonists were specifically and selectively blocked by the H1, H2, H3 or H4 receptor antagonists pyrilamine, ranitidine, clobenpropit or J1‐[(5‐chloro‐1H‐indol‐2‐yl)carbonyl]‐4‐methylpiperazine (JNJ 7777120), respectively. Clobenproprit reduced the excitatory response to histamine. Unlike in the guinea‐pig ENS (R)‐(−)‐α‐methylhistamine had no presynaptic actions in human submucous plexus. Application of agonists revealed receptor clustering which was as follows: 29% H1/H3, 27% H2, 20% H1/H2/H3, 10% H3, 7% H1/H2 and 7% H2/H3. Histamine excites human enteric neurones and this effect involves all four histamine receptors; most striking was the identification of an excitatory H3 mediated component and the discovery of H4 mediated neuronal excitation. These data may form the basis of identification of new targets to treat inflammatory and functional gut disorders.
A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions
Authors: Suzen Y. B. , Huang P. G. , Ashpis D. E. , Volino R. J. , Corke T. C. , Thomas F. O. , Huang J. , Lake J. P. , King P. I.
Published: July 2007

A transport equation for the intermittency factor is employed to predict the transitional flows in low-pressure turbines. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, μt, with the intermittency factor, γ. Turbulent quantities are predicted by using Menter’s two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model which can produce both the experimentally observed streamwise variation of intermittency and a realistic profile in the cross stream direction. The model had been previously validated against low-pressure turbine experiments with success. In this paper, the model is applied to predictions of three sets of recent low-pressure turbine experiments on the Pack B blade to further validate its predicting capabilities under various flow conditions. Comparisons of computational results with experimental data are provided. Overall, good agreement between the experimental data and computational results is obtained. The new model has been shown to have the capability of accurately predicting transitional flows under a wide range of low-pressure turbine conditions.
Application of a Dynamic Constitutive Law to Multilayer Metallic Sandwich Panels Subject to Impulsive Loads
Authors: Wei Z. , He M. Y. , Evans A. G.
Published: July 2007

The present paper describes an investigation that implements and assesses a dynamic continuum constitutive law for all-metallic sandwich panels. It also demonstrates its application to multilayer panels subject to water blast. Finite element calculations of unit cells are used to calibrate the model, especially the hardening curves at different strain rates. Once calibrated, the law is assessed by comparison with two sets of experiments. The dynamic response of panels impacted by Al foam projectiles at impulses comparable to those expected in water blast. The response of a multilayer core to an impulse caused by an explosion occurring in a cylindrical water column. The comparisons reveal that the overall deformation, average core strain, peak transmitted pressure, and velocities of the front and back faces are adequately predicted, inclusive of fluid/structure interactions. The inherent limitations of the approach are the underprediction of the plastic strains in the faces and incomplete assessment of stress oscillations beyond the peak. The former deficiency would pertain for any continuum representation for the core and would lead to problems in the prediction of face tearing. The latter may adversely affect the predictions of the impulse.
Scaling of Guide Vane Coolant Profiles and the Reduction of a Simulated Hot Streak
Authors: Jenkins Sean C. , Bogard David G.
Published: July 2007

The turbine section of a gas turbine engine is subjected to a nonuniform temperature distribution in the gas flow from the combustor. Regions of elevated temperatures, known as “hot streaks,” subject the turbine airfoil to high heat loads. In this study, the reduction of hot streaks by coolant from a film cooled nozzle guide vane was experimentally evaluated. Experiments were conducted with an approach mainstream turbulence level of 20% to simulate actual turbine conditions. The coolant distributions downstream of the vane were measured for varying blowing ratios and varying coolant density, and scaling methods were found for variations in both parameters. For this study, the hot streak peak was positioned to impact the vane at the stagnation line. Measurements of the hot streak strength with coolant blowing showed as much as a 55% decrease in peak temperature compared with no coolant.
Lattice Green’s Functions in Nonlinear Analysis of Defects
Authors: Haq S. , Movchan A. B. , Rodin G. J.
Published: July 2007

A method for analyzing problems involving defects in lattices is presented. Special attention is paid to problems in which the lattice containing the defect is infinite, and the response in a finite zone adjacent to the defect is nonlinear. It is shown that lattice Green’s functions allow one to reduce such problems to algebraic problems whose size is comparable to that of the nonlinear zone. The proposed method is similar to a hybrid finite-boundary element method in which the interior nonlinear region is treated with a finite element method and the exterior linear region is treated with a boundary element method. Method details are explained using an anti-plane deformation model problem involving a cylindrical vacancy.
Residual Elastic Strains in Autofrettaged Tubes: Variational Analysis by the Eigenstrain Finite Element Method
Authors: Korsunsky Alexander M. , Regino Gabriel M.
Published: July 2007

Autofrettage is a treatment process that uses plastic deformation to create a state of permanent residual stress within thick-walled tubes by pressurizing them beyond the elastic limit. The present paper presents a novel analytical approach to the interpretation of residual elastic strain measurements within slices extracted from autofrettaged tubes. The central postulate of the approach presented here is that the observed residual stress and residual elastic strains are secondary parameters, in the sense that they arise in response to the introduction of permanent inelastic strains (eigenstrains) by plastic deformation. The problem of determining the underlying distribution of eigenstrains is solved here by means of a variational procedure for optimal matching of the eigenstrain finite element model to the observed residual strains reported in the literature by Venter et al., 2000, J. Strain Anal., 35, p. 459. The eigenstrain distributions are found to be particularly simple, given by one-sided parabolas. The relationship between the measured residual strains within a thin slice to those in a complete tube is discussed.
Tolerance-Maps Applied to a Point-Line Cluster of Features
Authors: Ameta Gaurav , Davidson Joseph K. , Shah Jami J.
Published: July 2007

In this paper, groups of individual features, i.e., a point, a line, and a plane, are called clusters and are used to constrain sufficiently the relative location of adjacent parts. A new mathematical model for representing size and geometric tolerances is applied to a point-line cluster of features that is used to align adjacent parts in two-dimensional space. First, tolerance-zones are described for the point-line cluster. A Tolerance-Map® (Patent no. 69638242), a hypothetical volume of points, is then established which is the range of a mapping from all possible locations for the features in the cluster. A picture frame assembly of four parts is used to illustrate the accumulations of manufacturing variations, and the T-Maps® provide stackup relations that can be used to allocate size and orientational tolerances. This model is one part of a bilevel model that we are developing for size and geometric tolerances. At the local level the model deals with the permitted variations in a tolerance zone, while at the global level it interrelates all the frames of reference on a part or assembly.
Curtis Stage Nozzle/Rotor Aerodynamic Interaction and the Effect on Stage Performance
Authors: Rashid Stephen , Tremmel Matthew , Waggott John , Moll Randall
Published: July 2007

Curtis, or velocity compounded, stages commonly don’t achieve the same accuracy of performance prediction expected of most other turbine stages. A review of Curtis stage design practices, field wear, and dirt patterns, in conjunction with performance testing and computational fluid dynamics (CFD) modeling, determined that the nozzle/rotor aerodynamic interaction is far more complex than typical design and performance calculations assume. Understanding this nozzle/rotor interaction is key to obtaining both improved performance, and a more accurate performance prediction. This paper discusses the nature of this interaction, and it’s implications to Curtis stage performance prediction.
ArmillEye: Flexible Platform for Underwater Stereo Vision
Authors: Zoppi Matteo , Molfino Rezia
Published: July 2007

The paper describes ArmillEye, a 3-degree of freedom (DOF) flexible hybrid platform designed for agile underwater stereoptic vision. Effective telecontrol systems of remote operated vehicles require active and dexterous camera support in order to allow the operator to easily and promptly change the point of view, also improving the virtual reconstruction of the environment in difficult operative conditions (dirtiness, turbulence, and partial occlusion). The same concepts hold for visual servoing of autonomous underwater vehicles. ArmillEye was designed for this specific application; it is based on the concept of using a parallel-hybrid mechanism architecture that, in principle, allows us to minimize the ad hoc waterproof boxes (generally only for cameras) while the actuators, fixed to the base of the mechanism, can be placed into the main body of the underwater vehicle. This concept was revealed effective and was previously proposed for underwater arms. The synthesis of ArmillEye followed the specific aims of visual telecontrol and servoing, specifying vision workspace, dexterity, and dynamics parameters. Two versions of ArmillEye are proposed: the first one with two cameras to obtain a steroptic vision by using two viewpoints (two rotational freedoms with a fixed tilt or pan axis and vergence); the second one with one camera operated to obtain a stereoptic vision by using one viewpoint (two rotational freedoms with a fixed tilt or pan axis and extrusion).
Constraint-Based Design of Parallel Kinematic XY Flexure Mechanisms
Authors: Awtar Shorya , Slocum Alexander H.
Published: July 2007

This paper presents parallel kinematic XY flexure mechanism designs based on systematic constraint patterns that allow large ranges of motion without causing over-constraint or significant error motions. Key performance characteristics of XY mechanisms such as mobility, cross-axis coupling, parasitic errors, actuator isolation, drive stiffness, lost motion, and geometric sensitivity, are discussed. The standard double parallelogram flexure module is used as a constraint building-block and its nonlinear force-displacement characteristics are employed in analytically predicting the performance characteristics of two proposed XY flexure mechanism designs. Fundamental performance tradeoffs, including those resulting from the nonlinear load-stiffening and elastokinematic effects, in flexure mechanisms are highlighted. Comparisons between closed-form linear and nonlinear analyses are presented to emphasize the inadequacy of the former. It is shown that geometric symmetry in the constraint arrangement relaxes some of the design tradeoffs, resulting in improved performance. The nonlinear analytical predictions are validated by means of computational finite element analysis and experimental measurements.
Alice and Bob get away with it: A playlet
Authors: Sudbery Anthony
Published: July 2007

Alice and Bob use Aravind’s version of the Bell-Kochen-Specker theorem to fend off awkward questions about what exactly they were doing in Amsterdam last week.
Current Status of Veterinary Vaccines
Authors: Meeusen Els N. T. , Walker John , Peters Andrew , Pastoret Paul-Pierre , Jungersen Gregers
Published: July 2007

The major goals of veterinary vaccines are to improve the health and welfare of companion animals, increase production of livestock in a cost-effective manner, and prevent animal-to-human transmission from both domestic animals and wildlife. These diverse aims have led to different approaches to the development of veterinary vaccines from crude but effective whole-pathogen preparations to molecularly defined subunit vaccines, genetically engineered organisms or chimeras, vectored antigen formulations, and naked DNA injections. The final successful outcome of vaccine research and development is the generation of a product that will be available in the marketplace or that will be used in the field to achieve desired outcomes. As detailed in this review, successful veterinary vaccines have been produced against viral, bacterial, protozoal, and multicellular pathogens, which in many ways have led the field in the application and adaptation of novel technologies. These veterinary vaccines have had, and continue to have, a major impact not only on animal health and production but also on human health through increasing safe food supplies and preventing animal-to-human transmission of infectious diseases. The continued interaction between animals and human researchers and health professionals will be of major importance for adapting new technologies, providing animal models of disease, and confronting new and emerging infectious diseases.
Atmospheric Movement of Microorganisms in Clouds of Desert Dust and Implications for Human Health
Authors: Griffin Dale W.
Published: July 2007

Billions of tons of desert dust move through the atmosphere each year. The primary source regions, which include the Sahara and Sahel regions of North Africa and the Gobi and Takla Makan regions of Asia, are capable of dispersing significant quantities of desert dust across the traditionally viewed oceanic barriers. While a considerable amount of research by scientists has addressed atmospheric pathways and aerosol chemistry, very few studies to determine the numbers and types of microorganisms transported within these desert dust clouds and the roles that they may play in human health have been conducted. This review is a summary of the current state of knowledge of desert dust microbiology and the health impact that desert dust and its microbial constituents may have in downwind environments both close to and far from their sources.
Diversity of the trifunctional histidine biosynthesis gene (his) in cerealPhaeosphaeriaspecies
Authors: Wang Chih-Li , Malkus Arkadiusz , Zuzga Sabina M. , Chang Pi-Fang Linda , Cunfer Barry M. , Arseniuk Edward , Ueng Peter P.
Published: July 2007

Phaeosphaeria species are important causal agents of Stagonospora leaf blotch diseases in cereals. In this study, the nucleotide sequence and deduced polypeptide of the trifunctional histidine biosynthesis gene (his) are used to investigate the phylogenetic relationships and provide molecular identification among cereal Phaeosphaeria species. The full-length sequences of the his gene were obtained by PCR amplification and compared among cereal Phaeosphaeria species. The coding sequence of the his gene in wheat-biotype P. nodorum (PN-w) was 2697 bp. The his genes in barley-biotype P. nodorum (PN-b), two P. avenaria f. sp. triticea isolates (homothallic Pat1 and Pat3), and Phaeosphaeria species from Polish rye and dallis grass were 2694 bp. The his gene in heterothallic isolate Pat2, however, was 2693 bp because the intron had one fewer base. In P. avenaria f. sp. avenaria (Paa), the his gene was only 2670 bp long. The differences in the size of the his gene contributed to the variation in amino acid sequences in the gap region located between the phosphoribosyl-ATP pyrophosphohydrolase and histidinol dehydrogenase sub-domains. Based on nucleotide and deduced amino acid sequences of the his gene, Pat1 was not closely related to either PN-w or the Paa clade. It appears that rates of evolution of the his gene were fast in cereal Phaeosphaeria species. The possible involvement of meiotic recombination in genetic diversity of the his gene in P. nodorum is discussed.
Melanophore β-adrenoceptors in patterning in a flatfish, Pseudopleuronectes americanus
Authors: Burton D.
Published: July 2007

In vitro experiments were performed on melanophores bourne on scale slips sampled from three major areas (general background, dark band, and white spot) of the integumentary pattern of winter flounder, Pseudopleuronectes americanus (Walbaum, 1792). The effects of the respective β1- and β2-adrenoceptor agonists dobutamine and terbutaline and antagonists atenolol and ICI 118551 on pattern-related melanosome aggregation in response to exogenously applied L-noradrenaline were determined, as well as their effects on melanosome dispersion in balanced salt solution. The results demonstrate β1-adrenoceptor mediation in flatfish melanosome dispersion, with pattern-related variation, and also provide further evidence for β2-subtype involvement. Based on mammalian physiology, two β-subtypes will facilitate melanophore responsiveness to both neural and circulatory catecholamines. The in vivo role of these β-subtypes is discussed in relation to previously described attributes of the patterning behaviour of this species, which incorporates balances between α- and β-adrenoceptors. Dark band melanophores display a β-adrenoceptor bias, in contrast with other areas of the pattern, which would be consistent with their capacity for pigment dispersion in stressed flounders and with the slow paling of these bands during background-related responses.
Food supplementation experiments revisited: verifying that supplemental food is used by its intended recipients
Authors: Wirsing A.J. , Murray D.L.
Published: July 2007

Field-based food supplementation experiments can determine whether populations are limited by natural food availability. However, they may yield spurious results if added food is hoarded by dominants, exploited by immigrants, or delivered ineffectively. Surprisingly, population-level approaches accounting for these potential sources of bias have not been established. We explored responses of free-ranging snowshoe hares ( Lepus americanus Erxleben, 1777) to food supplementation by contrasting per capita browsing rates on three study sites with added food with those on three control sites during two winters. Food augmentation reduced foraging pressure by hares; this reduction was significant when browse species of high dietary importance were considered. By implication, hares on manipulated sites switched from favored natural foods to supplemental food, meaning that the extra food found its mark and was not heavily exploited by immigrants or hoarded by dominants. Demographic responses to food addition were not detected on the manipulated sites, indicating that the study population was not food limited. Given the success with which we detected the signal of supplementation and eliminated potential confounding factors, we suggest that future studies using food addition in the context of herbivore population dynamics would benefit from a more mechanistic approach; this may involve measurement of browsing rates on manipulated and control sites.
Fluctuating reproductive output and environmental stochasticity: do years with more reproducing females result in more offspring?
Authors: Pike D.A. , Stiner J.C.
Published: July 2007

Reproduction is a key life-history process often constrained by abiotic conditions, which affect resource availability and influence reproductive output, including the number of females in a population that reproduce within a given year. We investigated whether population-level fluctuations in reproductive effort (i.e., the number of nesting females) result in fluctuations in the number of offspring produced under environmentally stochastic conditions. Here we show that timing and frequency of tropical storms constrain reproductive success in green sea turtles ( Chelonia mydas (L., 1758)); in years when storms arrive early or when multiple storms occur most green sea turtle nests are inundated by seawater and fail to hatch. Although equal proportions of the nests were destroyed by tropical storms in peak and non-peak nesting years, significantly more hatchlings emerged from nests during peak nesting years. Thus, the cyclic patterns of green sea turtle reproduction result in cyclic patterns of hatchling emergence under high levels of nest failure owing to seawater inundation. Ultimately, green sea turtle reproductive success is constrained by the timing of tropical storms in relation to the nesting season. Continuing increases in the severity of tropical storms from changing global climates could contribute to a higher proportion of nesting seasons with low reproductive success, such that population growth rates are slowed, which may have long-term negative effects on the ability of this species to recover to historical levels.
Cell Cycle Regulation of DNA Replication
Authors: Sclafani R. A. , Holzen T. M.
Published: July 2007

Eukaryotic DNA replication is regulated to ensure all chromosomes replicate once and only once per cell cycle. Replication begins at many origins scattered along each chromosome. Except for budding yeast, origins are not defined DNA sequences and probably are inherited by epigenetic mechanisms. Initiation at origins occurs throughout the S phase according to a temporal program that is important in regulating gene expression during development. Most replication proteins are conserved in evolution in eukaryotes and archaea, but not in bacteria. However, the mechanism of initiation is conserved and consists of origin recognition, assembly of prereplication (pre-RC) initiative complexes, helicase activation, and replisome loading. Cell cycle regulation by protein phosphorylation ensures that pre-RC assembly can only occur in G1 phase, whereas helicase activation and loading can only occur in S phase. Checkpoint regulation maintains high fidelity by stabilizing replication forks and preventing cell cycle progression during replication stress or damage.
Development and Physiological Regulation of Intestinal Lipid Absorption. II. Dietary lipid absorption, complex lipid synthesis, and the intracellular packaging and secretion of chylomicrons
Authors: Mansbach Charles M. , Gorelick Fred
Published: July 2007

Research in dietary fat absorption has developed urgency because of the widely recognized epidemic of obesity in the United States. Despite its clinical importance, many controversies exist over some of the basic aspects of this process from the mechanisms of fatty acid uptake to the control of triacylglycerol export in chylomicrons. Recent advances have included the identification of a number of fatty acid transporters, the discovery of families of acyl-CoA synthetase long chains and acyltransferases, a physiological function for liver-fatty acid binding protein, and the characterization of the prechylomicron transport vesicle transporting chylomicrons from the endoplasmic reticulum to the Golgi.
2-APB protects against liver ischemia-reperfusion injury by reducing cellular and mitochondrial calcium uptake
Authors: Nicoud I. B. , Knox C. D. , Jones C. M. , Anderson C. D. , Pierce J. M. , Belous A. E. , Earl T. M. , Chari R. S.
Published: July 2007

Ischemia-reperfusion (I/R) injury is a commonly encountered clinical problem in liver surgery and transplantation. The pathogenesis of I/R injury is multifactorial, but mitochondrial Ca2+ overload plays a central role. We have previously defined a novel pathway for mitochondrial Ca2+ handling and now further characterize this pathway and investigate a novel Ca2+-channel inhibitor, 2-aminoethoxydiphenyl borate (2-APB), for preventing hepatic I/R injury. The effect of 2-APB on cellular and mitochondrial Ca2+ uptake was evaluated in vitro by using 45Ca2+. Subsequently, 2-APB (2 mg/kg) or vehicle was injected into the portal vein of anesthetized rats either before or following 1 h of inflow occlusion to 70% of the liver. After 3 h of reperfusion, liver injury was assessed enzymatically and histologically. Hep G2 cells transfected with green fluorescent protein-tagged cytochrome c were used to evaluate mitochondrial permeability. 2-APB dose-dependently blocked Ca2+ uptake in isolated liver mitochondria and reduced cellular Ca2+ accumulation in Hep G2 cells. In vivo I/R increased liver enzymes 10-fold, and 2-APB prevented this when administered pre- or postischemia. 2-APB significantly reduced cellular damage determined by hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling staining of liver tissue. In vitro I/R caused a dissociation between cytochrome c and mitochondria in Hep G2 cells that was prevented by administration of 2-APB. These data further establish the role of cellular Ca2+ uptake and subsequent mitochondrial Ca2+ overload in I/R injury and identify 2-APB as a novel pharmacological inhibitor of liver I/R injury even when administered following a prolonged ischemic insult.
Modeling upper and lower limb muscle volume by bioelectrical impedance analysis
Authors: Stahn Alexander , Terblanche Elmarie , Strobel Günther
Published: July 2007

Most studies employing bioelectrical impedance analysis (BIA) for estimating appendicular skeletal muscle mass using descriptive BIA models rely on statistical rather than biophysical principles. The aim of the present study was to evaluate the feasibility of estimating arm and leg muscle volume (MV) based on multiple bioimpedance measurements and using a recently proposed mathematical model and to compare this technique to conventional segmental BIA at high and low frequencies. MV of the arm and leg, respectively, was determined in 15 young, healthy, active men [age 22 ± 2 (SD) yr, total body fat 15.6 ± 5.1%] by magnetic resonance imaging (MRI) and BIA using a conventional and new bioimpedance model. MRI-determined MV for leg and arm was 6,268 ± 1,099 and 1,173 ± 172 cm3, respectively. Estimated MV by the new BIA model [leg: 6,294 ± 1,155 cm3 (50 kHz), 6,278 ± 1,103 cm3 (500 kHz); arm: 1,216 ± 172 cm3 (50 kHz), 1,155 ± 157 cm3 (500 kHz)] was not statistically different from MRI-determined MV (leg: P= 0.958; arm: P= 0.188). The new BIA model was superior to conventional BIA and performed best at 500 kHz for estimating leg MV as indicated by the lower relative total error [new: 3.6% (500 kHz), 5.2% (50 kHz); conventional: 7.6% (500 kHz) and 8.3% (50 kHz)]. In contrast, the new BIA model, both at 50 and 500 kHz, did not improve the accuracy for estimating arm MV [new: 10.8% (500 kHz), 10.6% (50 kHz); conventional: 11.8% (500 kHz), 11.4% (50 kHz)]. It was concluded that modeling of multiple BIA measurements has advantages for the determination of lower limb muscle volume in healthy, active adult men.
Soluble CD44 Is a Potential Marker for the Early Detection of Head and Neck Cancer
Authors: Franzmann Elizabeth J. , Reategui Erika P. , Pedroso Felipe , Pernas Francisco G. , Karakullukcu Baris M. , Carraway Kermit L. , Hamilton Kara , Singal Rakesh , Goodwin W. Jarrard
Published: July 2007

Introduction: Head and neck squamous cell carcinoma (HNSCC) is a devastating and deadly disease, largely because it is diagnosed in late stage. Cure rates, currently at 50%, could increase to >80% with early detection. In this study, we evaluate soluble CD44 (solCD44) as an early detection tool for HNSCC by determining whether it reliably distinguishes HNSCC from benign disease of the upper aerodigestive tract.

Methods: We carried out the solCD44 ELISA on oral rinses from 102 patients with HNSCC and 69 control patients with benign diseases of upper aerodigestive tract to determine the sensitivity and specificity of the test for differentiating HNSCC from benign disease. Furthermore, we did a pilot study using methylation-specific PCR primers on oral rinses from 11 HNSCC patients with low solCD44 levels and 10 benign disease controls.

Results: Mean salivary solCD44 levels were 24.4 ± 32.0 ng/mL for HNSCC patients (range, 0.99-201 ng/mL) and 9.9 ± 16.1 ng/mL (range, 0.73-124 ng/mL) for the patients with benign disease (P < 0.0001). Depending on cutoff point and HNSCC site, sensitivity ranged from 62% to 70% and specificity ranged from 75% to 88%. Nine of 11 HNSCC and 0 of 10 controls with low solCD44 levels showed hypermethylation of the CD44 promoter.

Conclusions: SolCD44 is elevated in the majority of HNSCC and distinguishes cancer from benign disease with high specificity. Whereas the solCD44 test lacks sensitivity by itself, methylation status of the CD44 gene seems to complement the solCD44 test. Our pilot data indicate that, together, these markers will detect HNSCC with very high sensitivity and specificity. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1348–55)
Dietary Patterns and Breast Cancer Risk in the Shanghai Breast Cancer Study
Authors: Cui Xiaohui , Dai Qi , Tseng Marilyn , Shu Xiao-Ou , Gao Yu-Tang , Zheng Wei
Published: July 2007

The association of breast cancer with dietary patterns such as a western diet has not been studied in Asian women. We examined this among Shanghai Breast Cancer Study participants. Cases were of ages 25 to 64 years, diagnosed 08/1996-03/1998, and identified through a rapid case ascertainment system supplemented by the Shanghai Cancer Registry. Controls, selected from the general population of urban Shanghai, were frequency matched to cases by 5-year age group. Participants provided information on diet, lifestyle, and reproductive factors. In principal component analysis among 1,556 controls, two patterns emerged: a “vegetable-soy” pattern (tofu, cauliflower, beans, bean sprouts, green leafy vegetables) and a “meat-sweet” pattern (shrimp, chicken, beef, pork, candy, desserts). In adjusted unconditional logistic regression analyses including 1,446 cases and 1,549 controls with complete covariate data, risk was not associated with the vegetable-soy pattern. It was associated with the meat-sweet pattern (4th versus 1st quartile: odds ratio, 1.3; 95% confidence interval, 1.0-1.7; Ptrend = 0.03), but only in postmenopausal women, specifically among those with estrogen receptor–positive tumors (4th versus 1st quartile: odds ratio, 1.9; 95% confidence interval, 1.1-3.3; Ptrend = 0.03). Our findings indicate that a western diet increases breast cancer risk in postmenopausal Chinese women. They also suggest the value of quantifying aggregate risk for common combinations of foods. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1443–8)
Mitochondrial Genetic Polymorphisms and Pancreatic Cancer Risk
Authors: Wang Liang , Bamlet William R. , de Andrade Mariza , Boardman Lisa A. , Cunningham Julie M. , Thibodeau Stephen N. , Petersen Gloria M.
Published: July 2007

The role of genes that influence the risk of developing pancreatic cancer (PC) has not been well studied. The mitochondrion, conventionally thought to be an organelle specific to energy metabolism, is in fact multifunctional and has been implicated in many diseases, including cancer. To evaluate whether single nucleotide polymorphisms in mitochondrial DNA (mtSNP) are associated with increased risk of PC, we screened Caucasian cases diagnosed or seen at the Mayo Clinic with primary pancreatic adenocarcinoma (n = 955), and healthy clinic-based Caucasian controls (n = 1,102). A total of 24 mtSNPs, including 10 of the most common tagSNPs, 7 non-tagSNPs in the coding region, and 7 common SNPs in the regulatory region were genotyped. For analysis, these samples were grouped into two phases, the “testing” set (474 cases and 615 controls), and the “validation” set (481 cases and 487 controls). In the testing set, one mtSNP (SNP11719) suggested an association in single SNP analysis, with an odds ratio of 1.34 (95% confidence intervals, 1.05-1.72; P = 0.020), but did not remain statistically significant after correction for multiple testing. In the validation set, none of the 24 variants indicated any association with PC. For haplogroup analysis, 10 core SNPs that form common haplogroups in Caucasians (1719, 4580, 7028, 8251, 9055, 10398, 12308, 13368, 13708, and 16391) were evaluated. No significant associations with PC were identified either by analyzing the two sets separately or combined (combined global P = 0.17). Overall, these results do not support a significant involvement of mitochondrial DNA variation in the risk of developing PC. Investigation of other mitochondrial genetic variations (i.e., nuclear-encoded mitochondrial proteins) would be necessary to elucidate any role of mitochondrial DNA variation in PC. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1455–9)
Common Variation in the BRCA1 Gene and Prostate Cancer Risk
Authors: Douglas Julie A. , Levin Albert M. , Zuhlke Kimberly A. , Ray Anna M. , Johnson Gregory R. , Lange Ethan M. , Wood David P. , Cooney Kathleen A.
Published: July 2007

Rare inactivating mutations in the BRCA1 gene seem to play a limited role in prostate cancer. To our knowledge, however, no study has comprehensively assessed the role of other BRCA1 sequence variations (e.g., missense mutations) in prostate cancer. In a study of 817 men with and without prostate cancer from 323 familial and early-onset prostate cancer families, we used family-based association tests and conditional logistic regression to investigate the association between prostate cancer and single nucleotide polymorphisms (SNPs) tagging common haplotype variation in a 200-kb region surrounding (and including) the BRCA1 gene. We also used the Genotype–Identity-by-Descent Sharing Test to determine whether our most strongly associated SNP could account for prostate cancer linkage to chromosome 17q21 in a sample of 154 families from our previous genome-wide linkage study. The strongest evidence for prostate cancer association was for a glutamine-to-arginine substitution at codon 356 (Gln356Arg) in exon 11 of the BRCA1 gene. The minor (Arg) allele was preferentially transmitted to affected men (P = 0.005 for a dominant model), with an estimated odds ratio of 2.25 (95% confidence interval, 1.21-4.20). Notably, BRCA1 Gln356Arg is not in strong linkage disequilibrium with other BRCA1 coding SNPs or any known HapMap SNP on chromosome 17. In addition, Genotype–Identity-by-Descent Sharing Test results suggest that Gln356Arg accounts (in part) for our prior evidence of prostate cancer linkage to chromosome 17q21 (P = 0.022). Thus, we have identified a common, nonsynonymous substitution in the BRCA1 gene that is associated with and linked to prostate cancer. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1510–6)
Immunoglobulin E Levels and Risk of Lymphoma in a Case-Control Study in Spain
Authors: Ellison-Loschmann Lis , Benavente Yolanda , Douwes Jeroen , Buendia Enric , Font Rebecca , Álvaro Tomás , Kogevinas Manolis , de Sanjosé Silvia
Published: July 2007

Epidemiologic studies have shown an inverse association between atopy and malignant lymphoma, but results are inconsistent. We investigated levels of IgE, before and after commencement of treatment, and evaluated lymphoma risk in relation to total and specific IgE levels. Serum levels of IgM, IgA, and IgG were also measured. We enrolled 467 newly diagnosed lymphoma cases and 544 hospital controls, matched for age, sex, and hospital. Lymphomas were histologically confirmed and categorized according to the WHO classification. Subjects provided blood for analysis of total and specific IgE levels, and total IgM, IgA, and IgG levels. Additional information was collected by interviewer-administered questionnaire. Controlling for age, sex, center, smoking status, and any treated asthma or eczema, we found that the overall risk of lymphoma was significantly lower in the high [odds ratio (OR), 0.39; 95% confidence interval (95% CI), 0.28-0.54] and middle (OR, 0.55; 95% CI, 0.40-0.74) tertiles for total serum IgE compared with the low tertile. Specific IgE to common aeroallergens (defined as ≥0.35 kU/L) was also inversely associated with risk of lymphoma (OR, 0.67; 95% CI, 0.45-1.00). Lymphoma was associated with IgA and IgM but not IgG. Mean levels of all immunoglobulins were decreased with more advanced malignancy, and total serum IgE levels were lower before treatment. The data suggest that the low levels of immunoglobulins seen in a wide range of lymphoma cases is likely to be linked to a lymphogenesis process rather than resulting from a selective protection due to an atopic process. Long-term cohort studies may be fundamental to fully evaluate these associations. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1492–8)
2-Amino-3,8-Dimethylimidazo-[4,5-f]Quinoxaline–Induced DNA Adduct Formation and Mutagenesis in DNA Repair–Deficient Chinese Hamster Ovary Cells Expressing Human Cytochrome P4501A1 and Rapid or Slow AcetylatorN-Acetyltransferase 2
Authors: Bendaly Jean , Zhao Shuang , Neale Jason R. , Metry Kristin J. , Doll Mark A. , States J. Christopher , Pierce William M. , Hein David W.
Published: July 2007

2-Amino-3,8-dimethylimidazo-[4,5-f]quinoxaline (MeIQx) is one of the most potent and abundant mutagens in the western diet. Bioactivation includes N-hydroxylation catalyzed by cytochrome P450s followed by O-acetylation catalyzed by N-acetyltransferase 2 (NAT2). In humans, NAT2*4 allele is associated with rapid acetylator phenotype, whereas NAT2*5B allele is associated with slow acetylator phenotype. We hypothesized that rapid acetylator phenotype predisposes humans to DNA damage and mutagenesis from MeIQx. Nucleotide excision repair–deficient Chinese hamster ovary cells were constructed by stable transfection of human cytochrome P4501A1 (CYP1A1) and a single copy of either NAT2*4 (rapid acetylator) or NAT2*5B (slow acetylator) alleles. CYP1A1 and NAT2 catalytic activities were undetectable in untransfected Chinese hamster ovary cell lines. CYP1A1 activity did not differ significantly (P > 0.05) among the CYP1A1-transfected cell lines. Cells transfected with NAT2*4 had 20-fold significantly higher levels of sulfamethazine N-acetyltransferase (P = 0.0001) and 6-fold higher levels of N-hydroxy-MeIQx O-acetyltransferase (P = 0.0093) catalytic activity than cells transfected with NAT2*5B. Only cells transfected with both CYP1A1 and NAT2*4 showed concentration-dependent cytotoxicity and hypoxanthine phosphoribosyl transferase mutagenesis following MeIQx treatment. Deoxyguanosine-C8-MeIQx was the primary DNA adduct formed and levels were dose dependent in each cell line and in the following order: untransfected < transfected with CYP1A1 < transfected with CYP1A1 and NAT2*5B < transfected with CYP1A1 and NAT2*4. MeIQx DNA adduct levels were significantly higher (P < 0.001) in CYP1A1/NAT2*4 than CYP1A1/NAT2*5B cells at all concentrations of MeIQx tested. MeIQx-induced DNA adduct levels correlated very highly (r2 = 0.88) with MeIQx-induced mutants. These results strongly support extrahepatic activation of MeIQx by CYP1A1 and a robust effect of human NAT2 genetic polymorphism on MeIQx-induced DNA adducts and mutagenesis. The results provide laboratory-based support for epidemiologic studies reporting higher frequency of heterocyclic amine-related cancers in rapid NAT2 acetylators. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1503–9)