bluuebunny/crossref_metadata_2025 huggingface dataset:
Escherichia coli
Induces DNA Double-Strand Breaks in Eukaryotic Cells
Authors: Nougayrède Jean-Philippe , Homburg Stefan , Taieb Frédéric , Boury Michèle , Brzuszkiewicz Elzbieta , Gottschalk Gerhard , Buchrieser Carmen , Hacker Jörg , Dobrindt Ulrich , Oswald Eric
Published: August 2006

Transient infection of eukaryotic cells with commensal and extraintestinal pathogenic
Escherichia coli
of phylogenetic group B2 blocks mitosis and induces megalocytosis. This trait is linked to a widely spread genomic island that encodes giant modular nonribosomal peptide and polyketide synthases. Contact with
E. coli
expressing this gene cluster causes DNA double-strand breaks and activation of the DNA damage checkpoint pathway, leading to cell cycle arrest and eventually to cell death. Discovery of hybrid peptide-polyketide genotoxins in
E. coli
will change our view on pathogenesis and commensalism and open new biotechnological applications.
Loss of a Harvested Fish Species Disrupts Carbon Flow in a Diverse Tropical River
Authors: Taylor Brad W. , Flecker Alexander S. , Hall Robert O.
Published: August 2006

Harvesting threatens many vertebrate species, yet few whole-system manipulations have been conducted to predict the consequences of vertebrate losses on ecosystem function. Here, we show that a harvested migratory detrital-feeding fish (Prochilodontidae:
Prochilodus mariae
) modulates carbon flow and ecosystem metabolism. Natural declines in and experimental removal of
Prochilodus
decreased downstream transport of organic carbon and increased primary production and respiration. Thus, besides its economic value,
Prochilodus
is a critical ecological component of South American rivers. Lack of functional redundancy for this species highlights the importance of individual species and, contrary to theory, suggests that losing one species from lower trophic levels can affect ecosystem functioning even in species-rich ecosystems.
Insignificant Change in Antarctic Snowfall Since the International Geophysical Year
Authors: Monaghan Andrew J. , Bromwich David H. , Fogt Ryan L. , Wang Sheng-Hung , Mayewski Paul A. , Dixon Daniel A. , Ekaykin Alexey , Frezzotti Massimo , Goodwin Ian , Isaksson Elisabeth , Kaspari Susan D. , Morgan Vin I. , Oerter Hans , Van Ommen Tas D. , Van der Veen Cornelius J. , Wen Jiahong
Published: August 2006

Antarctic snowfall exhibits substantial variability over a range of time scales, with consequent impacts on global sea level and the mass balance of the ice sheets. To assess how snowfall has affected the thickness of the ice sheets in Antarctica and to provide an extended perspective, we derived a 50-year time series of snowfall accumulation over the continent by combining model simulations and observations primarily from ice cores. There has been no statistically significant change in snowfall since the 1950s, indicating that Antarctic precipitation is not mitigating global sea level rise as expected, despite recent winter warming of the overlying atmosphere.
Going East: New Genetic and Archaeological Perspectives on the Modern Human Colonization of Eurasia
Authors: Mellars Paul
Published: August 2006

The pattern of dispersal of biologically and behaviorally modern human populations from their African origins to the rest of the occupied world between ∼60,000 and 40,000 years ago is at present a topic of lively debate, centering principally on the issue of single versus multiple dispersals. Here I argue that the archaeological and genetic evidence points to a single successful dispersal event, which took genetically and culturally modern populations fairly rapidly across southern and southeastern Asia into Australasia, and with only a secondary and later dispersal into Europe.
Dodeca-CLE Peptides as Suppressors of Plant Stem Cell Differentiation
Authors: Ito Yasuko , Nakanomyo Ikuko , Motose Hiroyasu , Iwamoto Kuninori , Sawa Shinichiro , Dohmae Naoshi , Fukuda Hiroo
Published: August 2006

In plants and animals, small peptide ligands that signal in cell-cell communication have been suggested to be a crucial component of development. A bioassay of single-cell transdifferentation demonstrates that a dodecapeptide with two hydroxyproline residues is the functional product of genes from the
CLE
family, which includes
CLAVATA3
in
Arabidopsis
. The dodecapeptide suppresses xylem cell development at a concentration of 10
–11
M and promotes cell division. An application, corresponding to all 26
Arabidopsis
CLE protein family members, of synthetic dodecapeptides reveals two counteracting signaling pathways involved in stem cell fate.
A Plant Peptide Encoded by
CLV3
Identified by in Situ MALDI-TOF MS Analysis
Authors: Kondo Tatsuhiko , Sawa Shinichiro , Kinoshita Atsuko , Mizuno Satoko , Kakimoto Tatsuo , Fukuda Hiroo , Sakagami Youji
Published: August 2006

The
Arabidopsis CLAVATA3
(
CLV3
) gene encodes a stem cell–specific protein presumed to be a precursor of a secreted peptide hormone. Matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI-TOF MS) applied to in situ
Arabidopsis
tissues determined the structure of a modified 12–amino acid peptide (MCLV3), which was derived from a conserved motif in the CLV3 sequence. Synthetic MCLV3 induced shoot and root meristem consumption as cells differentiated into other organs, displaying the typical phenotype of transgenic plants overexpressing
CLV3
. These results suggest that the functional peptide of CLV3 is MCLV3.
Single-Molecule, Motion-Based DNA Sequencing Using RNA Polymerase
Authors: Greenleaf William J. , Block Steven M.
Published: August 2006

We present a method for sequencing DNA that relies on the motion of single RNA polymerase molecules. When a given nucleotide species limits the rate of transcription, polymerase molecules pause at positions corresponding to the rare base. An ultrastable optical trapping apparatus capable of base pair resolution was used to monitor transcription under limiting amounts of each of the four nucleotide species. From the aligned patterns of pauses recorded from as few as four molecules, we determined the DNA sequence. This proof of principle demonstrates that the motion of a processive nucleic acid enzyme may be used to extract sequence information directly from DNA.
Requirement for Coronin 1 in T Lymphocyte Trafficking and Cellular Homeostasis
Authors: Föger Niko , Rangell Linda , Danilenko Dimitry M. , Chan Andrew C.
Published: August 2006

The evolutionarily conserved actin-related protein (Arp2/3) complex is a key component of actin filament networks that is dynamically regulated by nucleation-promoting and inhibitory factors. Although much is known about actin assembly, the physiologic functions of inhibitory proteins are unclear. We generated
coronin 1
–/–
mice and found that coronin 1 exerted an inhibitory effect on cellular steady-state F-actin formation via an Arp2/3-dependent mechanism. Whereas coronin 1 was required for chemokine-mediated migration, it was dispensable for T cell antigen receptor functions in T cells. Moreover, actin dynamics, through a mitochondrial pathway, was linked to lymphocyte homeostasis.
A FURTHER STUDY ON NON-ABELIAN PHASE SPACES: LEFT-SYMMETRIC ALGEBRAIC APPROACH AND RELATED GEOMETRY
Authors: BAI CHENGMING
Published: August 2006

The notion of non-abelian phase space of a Lie algebra was first formulated and then discussed by Kuperschmidt. In this paper, we further study the non-abelian phase spaces in terms of left-symmetric algebras. We interpret the natural appearance of left-symmetric algebras from the intrinsic algebraic properties and the close relations with the classical Yang–Baxter equation. Furthermore, using the theory of left-symmetric algebras, we study some interesting geometric structures related to phase spaces. Moreover, we also discuss the generalized phase spaces with certain non-trivial algebraic structures on the dual spaces.
FERROMAGNETISM OF THE HUBBARD MODEL AT STRONG COUPLING IN THE HARTREE–FOCK APPROXIMATION
Authors: BACH VOLKER , LIEB ELLIOTT H. , TRAVAGLIA MARCOS V.
Published: August 2006

As a contribution to the study of the Hartree–Fock theory, we prove rigorously that the Hartree–Fock approximation to the ground state of the d-dimensional Hubbard model leads to saturated ferromagnetism when the particle density (more precisely, the chemical potential μ) is small and the coupling constant U is large, but finite. This ferromagnetism contradicts the known fact that there is no magnetization at low density, for any U, and thus shows that HF theory is wrong in this case. As in the usual Hartree–Fock theory, we restrict attention to Slater determinants that are eigenvectors of the z-component of the total spin, 𝕊z = ∑x nx,↑ - nx,↓, and we find that the choice 2𝕊z = N = particle number gives the lowest energy at fixed 0 < μ < 4d.
SiC HOMOEPITAXY AND HETEROEPITAXY
Authors: BAKIN ANDREY S.
Published: August 2006

SiC bulk material quality and surface preparation do not satisfy all the requirements for direct device production. It is necessary to have high quality thick epitaxial layers with low background doping concentration for the fabrication of SiC high power, high voltage, high frequency devices. Different aspects of SiC homo- and heteroepitaxial growth are discussed in this chapter. The wafer surface has a large impact on epitaxial layers, heterostructures and finally on device properties. Thus wafer processing before epitaxial growth is discussed in detail.
OHMIC CONTACTS TO SIC
Authors: ROCCAFORTE FABRIZIO , LA VIA FRANCESCO , RAINERI VITO
Published: August 2006

In this chapter, the most significant results obtained in the last decade in the field of ohmic contacts to SiC are reviewed.

First, the basic concepts related to the physics of ohmic contacts and to the contact resistance measurement techniques are briefly reported.

Then, some aspects concerning the formation of low resistance (10-5-10-6 Ω cm 2) ohmic contacts on n-type and for p-type SiC are discussed, focusing on Ni -based and Al/Ti -based contacts.

Examples of innovative applications on practical devices are also reported, as the simultaneous formation of ohmic contacts on n- and p-type SiC for vertical power MOS devices, obtained adding Al to a standard Ni contact, and a single-metal technology for ohmic and rectifying contacts in MESFETs, using Ti or Ni without post-deposition annealing.
SILICON CARBIDE DIODES FOR MICROWAVE APPLICATIONS
Authors: Vassilevski Konstantin
Published: August 2006

Silicon carbide ( SiC ) offers significant advantages for microwave high power devises due to its unique electrical and thermal properties. This review presents a summary of the current position in the development of silicon carbide diodes operating at microwave frequencies: varactors, Schottky barrier mixer diodes, p-i-n and IMPATT diodes. Simplified theory of device operation is given for each kind of microwave diodes to derive the figures of merit, to estimate the potential silicon carbide performance for fabrication of these diodes and to compare SiC with conventional semiconductors. These analyses are followed by description of diode design, fabrication and measured characteristics.
EXISTENCE OF A SOLUTION TO THE CELL DIVISION EIGENPROBLEM
Authors: MICHEL PHILIPPE
Published: August 2006

We consider the cell division equation which describes the continuous growth of cells and their division in two pieces. Growth conserves the total number of cells while division conserves the total mass of the system but increases the number of cells. We give general assumptions on the coefficient so that we can prove the existence of a solution (λ, N, ϕ) to the related eigenproblem. We also prove that the solution can be obtained as the sum of an explicit series. Our motivation, besides its applications to the biology and fragmentation, is that the eigenelements allow to prove a priori estimates and long-time asymptotics through the General Relative Entropy.16.
LONG-RANGE PREDICTABILITY IN MODELS OF CELL POPULATIONS SUBJECTED TO PHASE-SPECIFIC DRUGS: GROWTH-RATE APPROXIMATION USING PROPERTIES OF POSITIVE COMPACT OPERATORS
Authors: KHEIFETZ Y. , KOGAN Y. , AGUR Z.
Published: August 2006

The aim of the present work is twofold: to develop numerical procedures for a priori determining whether a given cell population, having a distributed cell-cycle duration, will grow or decay when subjected to prescribed chemotherapy; to evaluate the cumulative error in the long-term predictions for such populations. We show that cell population dynamics under drug treatment can be modelled by iterative application of a compact operator on the initial cell age-distribution. We further show that this model can be approximated by iterative application of matrices on some finite-dimensional vector, containing initial conditions. Moreover, we develop a method for estimating the growth rate of cell population and show that in fully periodic treatments the estimated error does not grow as time tends to infinity. From the biomedical viewpoint this means that only fully periodic (strictly periodic) schedules can be considered for successfully predicting the long-term effect of chemotherapy. Thus, cyclic drug treatment is shown to be advantageous, not only in increasing selectivity of chemotherapy, as has been previously demonstrated, but also in increasing long-term predictability of specific treatment schedules.
FROM THE PHYSICAL LAWS OF TUMOR GROWTH TO MODELLING CANCER PROCESSES
Authors: BRÚ ANTONIO , HERRERO MIGUEL A.
Published: August 2006

This work is concerned with a model which has been proposed to describe the growth of solid tumors. More precisely, the model under consideration provides a procedure to extract information about the growth dynamics from the analysis of the geometrical properties of the interface tumor-host tissue. In particular, it is suggested that the tumor boundary should evolve according to some stochastic evolution equation. This is herein compared with other dynamic equations related to the growth of rough surfaces, and a number of questions concerning the asymptotics of the corresponding solutions (and its relation to that of their deterministic counterparts) are discussed.
EVOLVING INDUCTIVE GENERALIZATION VIA GENETIC SELF-ASSEMBLY
Authors: FÜCHSLIN RUDOLF M. , MAEKE THOMAS , TANGEN UWE , McCASKILL JOHN S.
Published: August 2006

We propose that genetic encoding of self-assembling components greatly enhances the evolution of complex systems and provides an efficient platform for inductive generalization, i.e. the inductive derivation of a solution to a problem with a potentially infinite number of instances from a limited set of test examples. We exemplify this in simulations by evolving scalable circuitry for several problems. One of them, digital multiplication, has been intensively studied in recent years, where hitherto the evolutionary design of only specific small multipliers was achieved. The fact that this and other problems can be solved in full generality employing self-assembly sheds light on the evolutionary role of self-assembly in biology and is of relevance for the design of complex systems in nano- and bionanotechnology.
PERMANENCE AND GLOBAL STABILITY FOR NONLINEAR DISCRETE MODEL
Authors: XIAOXING CHEN
Published: August 2006

A discrete nonlinear model is studied and sufficient conditions which guarantee the permanence of the model are obtained. Assuming that the coefficients in the model are periodic, the existence of periodic solutions are obtained. Sufficient conditions are obtained to ensure the global stability of the positive periodic solution by constructing a suitable Lyapunov function.
EXTINCTION IN GENETIC BIT-STRING MODEL WITH SEXUAL RECOMBINATION
Authors: STAUFFER D. , CEBRAT S.
Published: August 2006

We have analyzed the relations between the mutational pressure, recombination and selection pressure in the bit-string model with sexual reproduction. For specific sets of these parameters, we have found three phase transitions with one phase where populations can survive. In this phase, recombination enhances the survival probability. Even if recombination is associated, to some extent, with additional mutations it could be advantageous to reproduction, indicating that the frequencies of recombinations and recombination-associated mutations can self-organize in Nature. Partitioning the diploid genome into pairs of chromosomes independently assorted during gamete production enables recombinations between groups of genes without the risk of mutations and is also advantageous for the strategy of sexual reproduction.
MODEL OF INFLUENCE: FROM INDIVIDUAL DECISIONS TO LOCKED-IN MARKETS
Authors: GUALA SEBASTIAN D.
Published: August 2006

We introduce an agent-based, evolutionary model of decisions inspired by the increasing return theory. Agents have to choose between options taking into account their own preferences and externalities from their neighbors. The aim is to analyze the distribution of decisions in a square lattice domain and its dependence on the initial conditions. Numerical results show that an undesirable option may be adopted by the majority and may lock in markets by means of clever or lucky movements done at the beginning.
PREDICTABILITY OF CHAOS INHERENT IN THE OCCURRENCE OF SEVERE THUNDERSTORMS
Authors: CHAUDHURI SUTAPA
Published: August 2006

The purpose of the present study is to investigate the existence of deterministic chaos in the time series of occurrence or non-occurrence of severe thunderstorms of the pre-monsoon season over the Northeastern part of India. Results from the current study reveal the existence of chaos in the relevant time series. The corresponding predictabilities are also computed quantitatively. The study recommends that the formulation of numerical weather prediction models for forecasting the occurrence of this high frequency meso-scale convective system must take into account the intrinsic chaos.
Role of protein phosphatase 2A in calcium-dependent chloride secretion by human colonic epithelial cells
Authors: Chow Jimmy Y. C. , Barrett Kim E.
Published: August 2006

EGF inhibits carbachol-induced chloride secretion by regulating a basolateral potassium channel via phosphatidylinositol 3-kinase (PI 3-kinase) and PKCε activation. Although both EGF and carbachol cause tyrosine phosphorylation of p85 of PI 3-kinase, only EGF activates the enzyme. Serine phosphorylation of p85 is thought to suppress the lipid kinase of PI 3-kinase. Our present study examined whether the differential effects of carbachol and EGF on PI 3-kinase activity correspond to varying phosphorylation of p85, and the mechanisms and consequences. T84 colonic epithelial cells were treated with either EGF or carbachol. Cell lysates were immunoprecipitated with p85 antibody and blotted with either phosphotyrosine or phosphoserine antibodies. Protein phosphatase (PP) 1 and 2A activities were also measured. Both tyrosine and serine residues of p85 were phosphorylated by carbachol, whereas EGF induced only tyrosine phosphorylation. Moreover, EGF abolished carbachol-induced serine phosphorylation of p85 and activated PP2A without affecting PP1. Carbachol did not affect either phosphatase. Calyculin A or okadaic acid pretreatment reversed the inhibitory action of EGF on carbachol-induced chloride secretion and restored serine phosphorylation of p85. Although carbachol recruits p85, it phosphorylates both serine and tyrosine residues so that the lipid kinase of PI 3-kinase is inhibited. EGF results in p85 tyrosine phosphorylation as well as dephosphorylation of serine residues via the activation of PP2A. This explains the differential induction of PI 3-kinase enzyme activity in response to EGF and/or carbachol and has functional implications. Our data provide further insights into negative signals that regulate chloride secretion and into the molecular basis of signaling diversification in the intestinal epithelium.
Cellular mechanisms underlying prostaglandin-induced transient cAMP signals near the plasma membrane of HEK-293 cells
Authors: Rich Thomas C. , Xin Wenkuan , Mehats Celine , Hassell Kathryn A. , Piggott Leslie A. , Le Xuan , Karpen Jeffrey W. , Conti Marco
Published: August 2006

We have previously used cyclic nucleotide-gated (CNG) channels as sensors to measure cAMP signals in human embryonic kidney (HEK)-293 cells. We found that prostaglandin E1 (PGE1) triggered transient increases in cAMP concentration near the plasma membrane, whereas total cAMP levels rose to a steady plateau over the same time course. In addition, we presented evidence that the decline in the near-membrane cAMP levels was due primarily to a PGE1-induced stimulation of phosphodiesterase (PDE) activity, and that the differences between near-membrane and total cAMP levels were largely due to diffusional barriers and differential PDE activity. Here, we examine the mechanisms regulating transient, near-membrane cAMP signals. We observed that 5-min stimulation of HEK-293 cells with prostaglandins triggered a two- to threefold increase in PDE4 activity. Extracellular application of H89 (a PKA inhibitor) inhibited stimulation of PDE4 activity. Similarly, when we used CNG channels to monitor cAMP signals we found that both extracellular and intracellular (via the whole-cell patch pipette) application of H89, or the highly selective PKA inhibitor, PKI, prevented the decline in prostaglandin-induced responses. Following pretreatment with rolipram (a PDE4 inhibitor), H89 had little or no effect on near-membrane or total cAMP levels. Furthermore, disrupting the subcellular localization of PKA with the A-kinase anchoring protein (AKAP) disruptor Ht31 prevented the decline in the transient response. Based on these data we developed a plausible kinetic model that describes prostaglandin-induced cAMP signals. This model has allowed us to quantitatively demonstrate the importance of PKA-mediated stimulation of PDE4 activity in shaping near-membrane cAMP signals.
Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein-associated O-GlcNAc
Authors: Champattanachai Voraratt , Marchase Richard B. , Chatham John C.
Published: August 2006

Increased levels of protein O-linked N-acetylglucosamine ( O-GlcNAc) have been shown to increase cell survival following stress. Therefore, the goal of this study was to determine whether in isolated neonatal rat ventricular myocytes (NRVMs) an increase in protein O-GlcNAcylation resulted in improved survival and viability following ischemia-reperfusion (I/R). NRVMs were exposed to 4 h of ischemia and 16 h of reperfusion, and cell viability, necrosis, apoptosis, and O-GlcNAc levels were assessed. Treatment of cells with glucosamine, hyperglycemia, or O-(2-acetamido-2-deoxy-d-glucopyranosylidene)-amino- N-phenylcarbamate(PUGNAc), an inhibitor of O-GlcNAcase, significantly increased O-GlcNAc levels and improved cell viability, as well as reducing both necrosis and apoptosis compared with untreated cells following I/R. Alloxan, an inhibitor of O-GlcNAc transferase, markedly reduced O-GlcNAc levels and exacerbated I/R injury. The improved survival with hyperglycemia was attenuated by azaserine, which inhibits glucose metabolism via the hexosamine biosynthesis pathway. Reperfusion in the absence of glucose reduced O-GlcNAc levels on reperfusion compared with normal glucose conditions and decreased cell viability. O-GlcNAc levels significantly correlated with cell viability during reperfusion. The effects of glucosamine and PUGNAc on cellular viability were associated with reduced calcineurin activation as measured by translocation of nuclear factor of activated T cells, suggesting that increased O-GlcNAc levels may attenuate I/R induced increase in cytosolic Ca2+. These data support the concept that activation of metabolic pathways leading to an increase in O-GlcNAc levels is an endogenous stress-activated response and that augmentation of this response improves cell survival. Thus strategies designed to activate these pathways may represent novel interventions for inducing cardioprotection.
Increased maternal cortisol in late-gestation ewes decreases fetal cardiac expression of 11β-HSD2 mRNA and the ratio of AT1 to AT2 receptor mRNA
Authors: Reini Seth A. , Wood Charles E. , Jensen Ellen , Keller-Wood Maureen
Published: August 2006

Moderately elevated maternal cortisol levels late in gestation cause enlargement of the fetal sheep heart. We have used quantitative real-time PCR to examine expression of candidate genes in fetal hearts from mothers in whom cortisol levels were increased (by infusion of 1 mg cortisol·kg−1·day−1) or decreased (by adrenalectomy and replacement to 0.5 mg cortisol·kg−1·day−1) from 115 to 130 days gestation. Control ewes were not treated with steroid. Expression of mineralocorticoid receptor (MR), glucocorticoid receptor (GR), 11β-hydroxysteroid dehydrogenases 1 and 2 (11β-HSD1 and -2), IGF I and II, IGF receptors 1 and 2 (IGF-1R and IGF-2R), endothelial nitric oxide synthase, VEGF, myotrophin, angiotensinogen, the angiotensin receptors 1 and 2 (AT1R and AT2R), and the angiotensin converting enzymes 1 and 2 were measured. MR mRNA abundance in fetal hearts was found to be similar to that in adult kidney and hippocampus. Although there were no significant changes in most genes, 11β-HSD2 and IGF-1R expression were significantly decreased in the high cortisol group and 11β-HSD2 expression negatively correlated to left ventricular wall thickness. There was also a significant change in the ratio of AT receptor expression, with increased AT2R and decreased AT1R in the high cortisol group. MR, GR, and 11β-HSD1 immunoreactivity was found in cardiomyocytes and cardiac blood vessels in 126–128 day fetal sheep; in contrast 11β-HSD2 staining was predominantly in blood vessels. These results indicate that cortisol could indeed act in the fetal heart to induce enlargement and suggest that the renin-angiotensin system may play a role.
Insulin sensitivity, fat distribution, and adipocytokine response to different diets in lean and obese cats before and after weight loss
Authors: Hoenig M. , Thomaseth K. , Waldron M. , Ferguson D. C.
Published: August 2006

Obesity is a major health problem in cats and a risk factor for diabetes. It has been postulated that cats are always gluconeogenic and that the rise in obesity might be related to high dietary carbohydrates. We examined the effect of a high-carbohydrate/low-protein (HC) and a high-protein/low-carbohydrate (HP) diet on glucose and fat metabolism during euglycemic hyperinsulinemic clamp, adipocytokines, and fat distribution in 12 lean and 16 obese cats before and after weight loss. Feeding diet HP led to greater heat production in lean but not in obese cats. Regardless of diet, obese cats had markedly decreased glucose effectiveness and insulin resistance, but greater suppression of nonesterified fatty acids during the euglycemic hyperinsulinemic clamp was seen in obese cats on diet HC compared with lean cats on either diet or obese cats on diet HP. In contrast to humans, obese cats had abdominal fat equally distributed subcutaneously and intra-abdominally. Weight loss normalized insulin sensitivity; however, increased nonesterified fatty acid suppression was maintained and fat loss was less in cats on diet HC. Adiponectin was negatively and leptin positively correlated with fat mass. Lean cats and cats during weight loss, but not obese cats, adapted to the varying dietary carbohydrate/protein content with changes in substrate oxidation. We conclude that diet HP is beneficial through maintenance of normal insulin sensitivity of fat metabolism in obese cats, facilitating the loss of fat during weight loss, and increasing heat production in lean cats. These data also show that insulin sensitivity of glucose and fat metabolism can be differentially regulated in cats.
Length and curvature of the dog diaphragm
Authors: Boriek Aladin M. , Black Ben , Hubmayr Rolf , Wilson Theodore A.
Published: August 2006

Transdiaphragmatic pressure is a result of both tension in the muscles of the diaphragm and curvature of the muscles. As lung volume increases, the pressure-generating capability of the diaphragm decreases. Whether decrease in curvature contributes to the loss in transdiaphragmatic pressure and, if so, under what conditions it contributes are unknown. Here we report data on muscle length and curvature in the supine dog. Radiopaque markers were attached along muscle bundles in the midcostal region of the diaphragm in six beagle dogs of ∼8 kg, and marker locations were obtained from biplanar images at functional residual capacity (FRC), during spontaneous inspiratory efforts against a closed airway at lung volumes from FRC to total lung capacity, and during bilateral maximal phrenic nerve stimulation at the same lung volumes. Muscle length and curvature were obtained from these data. During spontaneous inspiratory efforts, muscle shortened by 15–40% of length at FRC, but curvature remained unchanged. During phrenic nerve stimulation, muscle shortened by 30 to nearly 50%, and, for shortening exceeding 52%, curvature appeared to decrease sharply. We conclude that diaphragm curvature is nearly constant during spontaneous breathing maneuvers in normal animals. However, we speculate that it is possible, if lung compliance were increased and the chest wall and the diameter of the diaphragm ring of insertion were enlarged, as in the case of chronic obstructive pulmonary disease, that decrease in diaphragm curvature could contribute to loss of diaphragm function.
Effects of short-term isocapnic hyperoxia and hypoxia on cardiovascular function
Authors: Thomson Alastair J. , Drummond Gordon B. , Waring W. Stephen , Webb David J. , Maxwell Simon R. J.
Published: August 2006

Both hypoxia and hyperoxia have major effects on cardiovascular function. However, both states affect ventilation and many previous studies have not controlled CO2 tension. We investigated whether hemodynamic effects previously attributed to modified O2 tension were still apparent under isocapnic conditions. In eight healthy men, we studied blood pressure (BP), heart rate (HR), cardiac index (CI), systemic vascular resistance index (SVRI) and arterial stiffness (augmentation index, AI) during 1 h of hyperoxia (mean end-tidal O2 79.6 ± 2.0%) or hypoxia (pulse oximeter oxygen saturation 82.6 ± 0.3%). Hyperoxia increased SVRI (18.9 ± 1.9%; P < 0.001) and reduced HR (−10.3 ± 1.0%; P < 0.001), CI (−10.3 ± 1.7%; P < 0.001), and stroke index (SI) (−7.3 ± 1.3%; P < 0.001) but had no effect on AI, whereas hypoxia reduced SVRI (−15.2 ± 1.2%; P < 0.001) and AI (−10.7 ± 1.1%; P < 0.001) and increased HR (18.2 ± 1.2%; P < 0.001), CI (20.2 ± 1.8%; P < 0.001), and pulse pressure (13.2 ± 2.3%; P = 0.02). The effects of hyperoxia on CI and SVRI, but not the other hemodynamic effects, persisted for up to 1 h after restoration of air breathing. Although increased oxidative stress has been proposed as a cause of the cardiovascular response to altered oxygenation, we found no significant changes in venous antioxidant or 8-iso-prostaglandin F2α levels. We conclude that both hyperoxia and hypoxia, when present during isocapnia, cause similar changes in cardiovascular function to those described with poikilocapnic conditions.
Voltage-Dependent Sodium Channels in Spinal Cord Motor Neurons Display Rapid Recovery From Fast Inactivation in a Mouse Model of Amyotrophic Lateral Sclerosis
Authors: Zona Cristina , Pieri Massimo , Carunchio Irene
Published: August 2006

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by a substantial loss of motor neurons in the spinal cord, brain stem, and motor cortex. Previous evidence showed that in a mouse model of a familial form of ALS expressing high levels of the human mutated protein Cu,Zn superoxide dismutase (Gly93→Ala, G93A), the firing properties of single motor neurons are altered to induce neuronal hyperexcitability. To determine whether the functionality of the macroscopic voltage-dependent Na+ currents is modified in G93A motor neurons, in the present work their physiological properties were examined. The voltage-dependent sodium channels were studied in dissociated motor neurons in culture from nontransgenic mice (Control), from transgenic mice expressing high levels of the human wild-type protein [superoxide dismutase 1 (SOD1)], and from G93A mice, using the whole cell configuration of the patch-clamp recording technique. The voltage dependency of activation and of steady-state inactivation, the kinetics of fast inactivation and slow inactivation of the voltage-dependent Na+ channels were not modified in the mutated mice. Conversely, the recovery from fast inactivation was significantly faster in G93A motor neurons than that in Control and SOD1. The recovery from fast inactivation was still significantly faster in G93A motor neurons exposed for different times (3–48 h) and concentrations (5–500 μM) to edaravone, a free-radical scavenger. Clarification of the importance of these changes in membrane ion channel functionality may have diagnostic and therapeutic implications in the pathogenesis of ALS.
Intrinsic Properties Shape the Firing Pattern of Ventral Horn Interneurons From the Spinal Cord of the Adult Turtle
Authors: Smith Morten , Perrier Jean-François
Published: August 2006

Interneurons in the ventral horn of the spinal cord play a central role in motor control. In adult vertebrates, their intrinsic properties are poorly described because of the lack of in vitro preparations from the spinal cord of mature mammals. Taking advantage of the high resistance to anoxia in the adult turtle, we used a slice preparation from the spinal cord. We used the whole cell blind patch-clamp technique to record from ventral horn interneurons. We characterized their firing patterns in response to depolarizing current pulses and found that all the interneurons fired repetitively. They displayed bursting, adapting, delayed, accelerating, or oscillating firing patterns. By combining electrophysiological and pharmacological tests, we showed that interneurons expressed slow inward rectification, plateau potential, voltage-sensitive transient outward rectification, and low-threshold spikes. These results demonstrate a diversity of intrinsic properties that may enable a rich repertoire of activity patterns in the network of ventral horn interneurons.
Control of the Subthalamic Innervation of the Rat Globus Pallidus by D2/3and D4Dopamine Receptors
Authors: Hernández Adán , Ibáñez-Sandoval Osvaldo , Sierra Arturo , Valdiosera René , Tapia Dagoberto , Anaya Verónica , Galarraga Elvira , Bargas José , Aceves Jorge
Published: August 2006

The effects of activating dopaminergic D2/3and D4receptors during activation of the subthalamic projection to the globus pallidus (GP) were explored in rat brain slices using the whole cell patch-clamp technique. Byocitin labeling and both orthodromic and antidromic activation demonstrated the integrity of some subthalamopallidal connections in in vitro parasagittal brain slices. Excitatory postsynaptic currents (EPSCs) that could be blocked by CNQX and AP5 were evoked onto pallidal neurons by local field stimulation of the subthalamopallidal pathway in the presence of bicuculline. Bath application of dopamine and quinpirole, a dopaminergic D2-class receptor agonist, reduced evoked EPSCs by about 35%. This effect was only partially blocked by sulpiride, a D2/3receptor antagonist. The sulpiride-sensitive reduction of the subthalamopallidal EPSC was associated with an increase in the paired-pulse ratio (PPR) and a reduction in the frequency but not the mean amplitude of spontaneous EPSCs (sEPSCs), indicative of a presynaptic site of action, which was confirmed by variance–mean analysis. The sulpiride-resistant EPSC reduction was mimicked by PD 168,077 and blocked by L-745,870, selective D4receptor agonist and antagonist, respectively, suggesting the involvement of D4receptors. The reduction of EPSCs produced by PD 168,077 was not accompanied by changes in PPR or the frequency of sEPSCs; however, it was accompanied by a reduction in mean sEPSC amplitude, indicative of a postsynaptic site of action. These results show that dopamine modulates subthalamopallidal excitation by presynaptic D2/3and postsynaptic D4receptors. The importance of this modulation is discussed.
Loss of Binocular Responses and Reduced Retinal Convergence During the Period of Retinogeniculate Axon Segregation
Authors: Z̆iburkus Jokūbas , Guido William
Published: August 2006

In the developing mammalian visual system, axon terminals from the two eyes overlap in the dorsal lateral geniculate nucleus (LGN) but then undergo a period of refinement and segregate to form distinct eye-specific domains. We report on the changes in synaptic transmission that occur in rodent LGN during the period of retinogeniculate axon segregation by using anterograde labeling techniques in conjunction with an in vitro preparation where large segments of each optic nerve are preserved. Anterograde labeling of retinal projections in early postnatal day (P) rats with cholera toxin β subunit indicated an age-related recession in uncrossed retinal projections. Between P2 and P5 uncrossed projections occupied as much as 50% of the LGN and overlapped substantially with crossed projections. Between the first and second postnatal week uncrossed projections receded, so by P14 they assumed an adultlike profile occupying 15–20% of LGN and showed little or no overlap with crossed projections. The postsynaptic responses of LGN cells evoked by the separate stimulation of each optic nerve indicated that before P14, many relay cells were binocularly innervated and received at least four to six inputs from each eye. However, these features of retinogeniculate connectivity were transient and their attrition occurred in concert with a retraction of retinal arbors into nonoverlapping, eye-specific regions. By P18 cells were monocularly innervated and received input from one to three retinal ganglion cells. These results provide a better understanding of the underlying changes in synaptic circuitry that occur during the anatomical segregation of retinal inputs into eye-specific territories.
In Between Military and Militia: The Dynamics of the Security Forces in the Communal Conflict in Ambon
Authors: Azca Muhammad Najib
Published: August 2006

This article presents and discusses the role of the security forces in the communal conflict in Ambon, Indonesia. Though it shares the view articulated by many scholars and social obervers that the security forces played partisan roles in prolonging the Ambon conflict, it criticizes the tendency to overstate their role and see them as a single homogenous actor. Based on extensive research and fieldwork, this paper argues that the dynamics of the role of the security forces in the conflict in Ambon evolved in concert with the dynamics of the conflict itself and was influenced by both local and national factors and their respective actors. It also examines the issue in the context of civil-military relations in the aftermath of the collapse of the authoritarian regime, with particular attention paid to its impact on security sector reform.
Why the Madurese? Ethnic Conflicts in West and East Kalimantan Compared
Authors: De Jonge Huub , Nooteboom Gerben
Published: August 2006

Around the recent turn of the century, violent clashes between Madurese and other ethnic groups took place in the provinces of West and Central Kalimantan. At least 1200 Madurese were killed, with several hundred thousands internally displaced. However, in the provinces of South and East Kalimantan, which also have Madurese minorities, such eruptions of violence did not occur. To reach a better understanding of the background, conditions and causes of such ethnic violence, we have compared the relationships between the Madurese and other population groups in conflict-ridden West Kalimantan and conflictfree East Kalimantan. The comparison shows that there are significant dissimilarities between the two regions with regard to the ethnic composition of the population, cultural attitudes, access to natural resources and political competition. Together with the negative characteristics attributed to the Madurese by other groups, these can largely explain why this minority, during the recent regime change, became the target of the frustrations and aspirations of others in the western part of Kalimantan but not in the eastern part.
Just Talk? Anthropological Reflections on the Object of Media Studies in Indonesia
Authors: Hobart Mark
Published: August 2006

This article sets out to reflect critically on the object of study in media and communication studies. It argues that not only the conventional analytical categories but also the modes of explanation and interpretation used are both problematic and Eurocentric, because they are mediated by a whole series of industrial and intellectual practices which have remained unacknowledged. The article aims to show how taking media-related practices as an object of study, requires radical revision to much of media studies. Central among these practices is commentary of various kinds. The mass media spend much time commenting on themselves and one another, just as research through questionnaires, focus groups and interviews are invitations to participants to comment. Commenting in its many forms emerges therefore as an important way of indicating how articulation, a central concept in media and cultural studies, works. Drawing on examples from Indonesia, an analysis of commentary provides a way of understanding how audiences relate to media production, not least because people talk about the mass media and how they are implicated, or perhaps even disarticulated by the media. In failing to appreciate how commentary works, media scholars are complicit in this process of disarticulation, a notion elaborated in the article.
Nationalist and Separatist discourses in cyclical violence in Papua
Authors: Widjojo Muridan
Published: August 2006

This article is an attempt to review the cyclical history of violence in Papua, Indonesia. I analyse the ways in which the Indonesian security forces employ nationalist discourse to justify conduct in Papua that includes obstructing justice and intimidating human rights advocates. The birth of the human rights movement in Papua in the mid 1990s in many ways has challenged this security approach. Human rights advocates not only expose excessive violent behaviour on the part of the military during 'secret' operations, but also question the high military troop levels and the conduct of the national police in Papua. The advent of Reformasi in 1998 revived all over the province the demands for secession that had been dormant during the 1980s and 1990s. This has served the army as a pretext to maintain its strong presence in Papua. My main argument is that both the pro-independence Papuans and the security forces have a vested interest in keeping the secession issue as the dominant discourse on Papua. From the early 1960s to 2003, the security forces have been able to argue that the state is under threat of separatism. In turn, the violence and impunity Papuans endure provides the basis for their ever-growing discourse of independence.
Fear and Uncertainty: Local Perceptions of the Sorcerer and the State in an Indonesian Witch-hunt
Authors: Herriman Nicholas
Published: August 2006

In 1998, around one hundred alleged sorcerers were killed in Banyuwangi District, East Java. Most scholars treated the killings as a conspiracy. My evidence indicates that local residents have been killing 'sorcerers' for at least the past half century. Rather than a conspiracy, the increased numbers of killings in 1998 can be attributed to: 1. A perception that the reform movement ca 1998 incorporated violence against sorcerers, as much as social or political protest; 2. Attempts by officials to safely relocate 'sorcerers', by identifying those to be relocated. Officials thereby inadvertently confirmed the identities of 'sorcerers' and gave encouragement to potential killers; 3. A perception that officers of the police and army were afraid they would be accused of human rights violations if they prevented local residents killing 'sorcerers'.
Of Spontaneity and Conspiracy Theories: Explaining Violence in Central Kalimantan
Authors: Bouvier Hélène , Smith Glenn
Published: August 2006

The massacres in Sampit, Central Kalimantan in 2001 were the latest in a series of horrific clashes between Madurese migrants and indigenous peoples, which, since 1996, killed thousands and displaced hundreds of thousands, the primary victims being Madurese. As in earlier clashes, a relatively minor incident or an isolated killing served as the trigger to a conflict more profoundly rooted in interethnic grievances, historical injustices, growing ethnic empowerment, and burgeoning political competition in Indonesia's transition to decentralized governance. The article compares and evaluates Dayak and Madurese accounts of the violence, its background and causes, focusing on a key period when latent tensions transformed into mass killings. Two different theories emerge, each positing a conspiracy: the Dayaks regarded the Madurese as out to take over the province and the Madurese accused the Dayaks of plotting to take over their land and jobs. The Dayak theory further sees the problem as one of cultural incompatibility and claims that the Dayak people spontaneously rose to pre-empt the threat posed by the Madurese. This notion that the violence was caused by cultural factors was factored into government policy and peace initiatives, and was to affect the prospects for reconciliation and return of the displaced. The authors suggest these understandings of violence played a key role in determining how the reconciliation process was run.
A Brief Guide to Structural Equation Modeling
Authors: Weston Rebecca , Gore Paul A.
Published: August 2006

To complement recent articles in this journal on structural equation modeling (SEM) practice and principles by Martens and by Quintana and Maxwell, respectively, the authors offer a consumer’s guide to SEM. Using an example derived from theory and research on vocational psychology, the authors outline six steps in SEM: model specification, identification, data preparation and screening, estimation, evaluation of fit, and modification. In addition, the authors summarize the debates surrounding some aspects of SEM (e.g., acceptable sample size, fit indices), with recommendations for application. They also discuss the need for considering and testing alternative models and present an example, with details on determining whether alternative models result in a significant improvement in fit to the observed data.
Treating Cronbach’s Alpha Reliability Coefficients as Data in Counseling Research
Authors: Helms Janet E. , Henze Kevin T. , Sass Terry L. , Mifsud Venus A.
Published: August 2006

Scientific associations and measurement experts in psychology and education have voiced various standards and best-practice recommendations concerning reliability data over the years. Yet in the counseling psychology literature, there is virtually no single-source compilation and articulation of good practices for reporting, analyzing, and interpreting reliability to guide applied researchers intending to use scales rather than develop them. Therefore, focusing on Cronbach’s alpha internal consistency reliability estimates, this article (a) defines and provides rationales for seven broad categories of good practices for reporting, analyzing, interpreting, and using reliability data and (b) illustrates some pragmatic strategies for implementing the good practices with respect to reliability data in quantitative studies involving already-developed scales. The authors’ recommendations for good rather than best practices acknowledge that additional or alternative practices may be required when scale development is the researcher’s focus. The authors summarize their good practices in tabular form.