bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of
Bordetella pertussis
in a Critically Ill Human Immunodeficiency Virus-Infected Patient by Direct Genotypical Analysis of Gram-Stained Material and Discrimination from
B. holmesii
by Using a Unique
recA
Gene Restriction Enzyme Site
Authors: Vielemeyer Ole , Crouch Jill Y. , Edberg Stephen C. , Howe John G.
Published: February 2004

Bordetella pertussis
was diagnosed in a human immunodeficiency virus-infected patient by a newly developed method in which bacterial DNA is amplified directly from sputum Gram-stained slides. The validation of the method is described along with an additional new PCR-based assay that can distinguish between
B. pertussis
and
Bordetella holmesii
.
Prevalence of Vancomycin-Resistant
Enterococcus
in Prenatal Screening Cultures
Authors: Miller Melissa B. , Allen Sonia L. , Mangum Mary Ellen , Doutova Anastassia , Gilligan Peter H.
Published: February 2004

Recommendations for the perinatal treatment of women colonized with
Streptococcus agalactiae
include vancomycin prophylaxis for those with severe penicillin allergies and antibiotic-resistant organisms. Because of potential postpartum infections due to vancomycin-resistant enterococci (VRE) and the possible spread of vancomycin resistance, the prevalence of VRE in prenatal screening cultures was determined.
Immunologically Silent Autochthonous Acute Hepatitis E Virus Infection in France
Authors: Mansuy Jean Michel , Peron Jean Marie , Bureau Christophe , Alric Laurent , Vinel Jean Pierre , Izopet Jacques
Published: February 2004

Hepatitis E is an acute and self-limiting hepatitis, and the causative agent, hepatitis E virus, is excreted in feces and orally transmitted. The disease is common in Asia and Africa, causing outbreaks or sporadic cases. In Europe, the infection is generally observed after a history of travel in an area of endemicity. We report on an autochthonous case in southwestern France in which the diagnosis was based on molecular tools rather than serological testing.
Ethical review of health research: a perspective from developing country researchers
Authors: Hyder A A , Wali S A , Khan A N , Teoh N B , Kass N E , Dawson L
Published: February 2004

Background:Increasing collaboration between industrialised and developing countries in human research studies has led to concerns regarding the potential exploitation of resource deprived countries. This study, commissioned by the former National Bioethics Advisory Commission of the United States, surveyed developing country researchers about their concerns and opinions regarding ethical review processes and the performance of developing country and US international review boards (IRBs).

Methods:Contact lists from four international organisations were used to identify and survey 670 health researchers in developing countries. A questionnaire with 169 questions explored issues of IRB review, informed consent, and recommendations.

Results:The majority of the developing country researchers were middle aged males who were physicians and were employed by educational institutions, carrying out research on part time basis. Forty four percent of the respondents reported that their studies were not reviewed by a developing country IRB or Ministry of Health and one third of these studies were funded by the US. During the review process issues such as the need for local language consent forms and letters for approval, and confidentiality protection of participants were raised by US IRBs in significantly higher proportions than by host country IRBs.

Conclusion:This survey indicates the need for the ethical review of collaborative research in both US and host countries. It also reflects a desire for focused capacity development in supporting ethical review of research.
New European guidelines for the use of stored human biological materials in biomedical research
Authors: Trouet C
Published: February 2004

The increasing possibilities for using tissue for research and development in genetics and biotechnology have made stored human biological materials more important than ever. Using stored human biological materials raises many legal and ethical questions. On an international level however, the use of these materials has not been regulated in a detailed manner so far. The Council of Europe recently declassified the text of the proposal for an instrument on the use of archived human biological materials in biomedical research for public consultation. The purpose of this paper is to comment on this document regarding its primary goal, which is to protect the rights and fundamental freedoms of the individual whose biological materials could be included in a research project. The guidelines offer good basic protection for sources of identifiable human biological materials but, surprisingly, offer no protection to sources of anonymous or anonymised materials.
Institutional ethics review of clinical study agreements
Authors: DuVal G
Published: February 2004

Clinical Study Agreements (CSAs) can have profound effects both on the protection of human subjects and on the independence of investigators to conduct research with scientific integrity. Sponsors, institutions, and even investigators may fail to give adequate attention to these issues in the negotiation of CSAs. Despite the key role of CSAs in structuring ethically important aspects of research, they remain largely unregulated and unreviewed for adherence to ethical norms. Academic institutions routinely enter into research contracts that fail to meet adequate ethical standards. This is a failing that can have serious consequences.

Accordingly, it is necessary that some independent body have the authority both to review research contracts for compliance with norms of subject protection and ethical integrity, and to reject studies that fail to meet ethical standards. Such review should take place prior to the start of research, not later. Because of its expertise and authority, the institutional ethics review board (IRB or REB) is the appropriate body to undertake such review. Much recent commentary has focused on contractual restrictions on the investigator’s freedom to publish research findings. The Olivieri experience, and that of other investigators, has brought freedom of publication issues into sharp focus. Clinical study agreements also raise a number of other ethical issues relating to human subjects and research integrity, however, including disclosures relating to patient safety, data analysis and reporting, budget, confidentiality, and premature termination of the study. This paper describes the ethical issues at stake in structuring such agreements and suggests ethical standards to guide institutional ethics review.
Biomedical conflicts of interest: a defence of the sequestration thesis—learning from the cases of Nancy Olivieri and David Healy
Authors: Schafer A
Published: February 2004

No discussion of academic freedom, research integrity, and patient safety could begin with a more disquieting pair of case studies than those of Nancy Olivieri and David Healy. The cumulative impact of the Olivieri and Healy affairs has caused serious self examination within the biomedical research community. The first part of the essay analyses these recent academic scandals. The two case studies are then placed in their historical context—that context being the transformation of the norms of science through increasingly close ties between research universities and the corporate world. After a literature survey of the ways in which corporate sponsorship has biased the results of clinical drug trials, two different strategies to mitigate this problem are identified and assessed: a regulatory approach, which focuses on managing risks associated with industry funding of university research, and a more radical approach, the sequestration thesis, which counsels the outright elimination of corporate sponsorship. The reformist approach is criticised and the radical approach defended.
Supporting whistleblowers in academic medicine: training and respecting the courage of professional conscience
Authors: Faunce T , Bolsin S , Chan W-P
Published: February 2004

Conflicts between the ethical values of an organisation and the ethical values of the employees of that organisation can often lead to conflict. When the ethical values of the employee are considerably higher than those of the organisation the potential for catastrophic results is enormous. In recent years several high profile cases have exposed organisations with ethical weaknesses. Academic medical institutions have exhibited such weaknesses and when exposed their employees have almost invariably been vindicated by objective inquiry. The mechanisms that work to produce such low ethical standards in what should be exemplary organisations are well documented and have been highlighted recently. The contribution of elements of medical training in eroding ethical standards of medical students have also been emphasised recently and strategies proposed to reduce or reverse this process. The ability to rapidly change the ethical and professional culture of graduate medical trainees may help to deal with some of the perceived problems of declining ethical standards in academic medicine.
TOP-CHARM ASSOCIATED PRODUCTION VIA SUSY FCNC COUPLINGS AT THE CERN LHC IN THE MSSM
Authors: LIU JIAN JUN , LI CHONG SHENG , YANG LI LIN , JIN LI GANG
Published: February 2004

We evaluate the total cross-sections of top-charm associated production induced by SUSY–QCD FCNC at the LHC within the general unconstrained MSSM framework. Our results show that these production rates may be as large as a few pb for favorable parameter values allowing by current precise experiments. It means that the LHC may produce abundant events of this process, and the SUSY FCNC effects through the above process may be observable in the future experiments.
COLOR VAN DER WAALS FORCES BETWEEN HEAVY QUARKONIA IN EFFECTIVE QCD
Authors: NARȨBSKI JAKUB
Published: February 2004

The perturbative renormalization group for light-front QCD Hamiltonians produces a logarithmically rising inter-quark potential already in second order, when Fock sectors with effective (constituent) gluons are truncated. In this approach the quark self-interaction renders [Formula: see text] states unphysical if they are not color singlets. There is a question if this mechanism solves the problem of too strong color van der Waals forces between heavy quarkonia, which emerge in potential models not directly derivable from QCD. This article shows that such forces do exist in this approach, and estimates their strength with the result that they are on the border of exclusion, while more advanced calculation is possible.
INTERACTION OF VORTICES WITH AN EXTERNAL FIELD
Authors: SHNIR YA.
Published: February 2004

The interaction of a magnetic flux vortex with weak external fields is considered in the framework of the Abelian Higgs model. The approach is based on the calculation of the zero-mode excitation probability in the external field. The excitation of the field configuration is found perturbatively. As an example we consider the effect of interaction with an external current. The linear in the scalar field perturbation is also considered.
MUONIUM–ANTIMUONIUM OSCILLATIONS AND MASSIVE MAJORANA NEUTRINOS
Authors: CLARK T. E. , LOVE S. T.
Published: February 2004

The electron and muon number violating muonium–antimuonium oscillation process can proceed provided that neutrinos have nonzero masses and mix among the various generations. Modifying the Standard Model only by the inclusion of singlet right-handed neutrino fields and allowing for general neutrino masses and mixings, the leading order matrix element contributing to this process is computed. For the particularly interesting case where the neutrino masses are generated by a seesaw mechanism with a very large Majorana mass MR≫MW, it is found that both the very light and very heavy Majorana neutrinos each give comparable contributions to the oscillation time scale proportional to [Formula: see text]. Present experimental limits set by the non-observation of the oscillation process sets a lower limit on MR of roughly of order 104 GeV.
NON-UNITARY AND UNITARY TRANSITIONS IN GENERALIZED QUANTUM MECHANICS, NEW SMALL PARAMETER AND INFORMATION PROBLEM SOLVING
Authors: SHALYT-MARGOLIN A. E.
Published: February 2004

Quantum Mechanics of the Early Universe is considered as deformation of a well-known Quantum Mechanics. Similar to previous works of the author, the principal approach is based on deformation of the density matrix with concurrent development of the wave function deformation in the respective Schrödinger picture, the associated deformation parameter being interpreted as a new small parameter. It is demonstrated that the existence of black holes in the suggested approach in the end twice causes non-unitary transitions resulting in the unitarity. In parallel this problem is considered in other terms: entropy density, Heisenberg algebra deformation terms, respective deformations of Statistical Mechanics — all showing the identity of the basic results. From this an explicit solution for Hawking's information paradox has been derived.
EXTENDED DIFFEOMORPHISM ALGEBRAS IN (QUANTUM) GRAVITATIONAL PHYSICS
Authors: ALDAYA V. , JARAMILLO J. L.
Published: February 2004

We construct an explicit representation of the algebra of local diffeomorphisms of a manifold with realistic dimensions. This is achieved in the setting of a general approach to the (quantum) dynamics of a physical system which is characterized by the fundamental role assigned to a basic underlying symmetry. The mathematical formalism developed addresses the relevant gravitational notions by means of the addition of some extra structure. The specific manners in which this is accomplished, together with their corresponding physical interpretation, lead to different gravitational models. Distinct strategies are in fact briefly outlined, showing the versatility of the present conceptual framework.
HOMOGENIZATION OF BOUNDARY VALUE PROBLEMS AND SPECTRAL PROBLEMS FOR NEUTRON TRANSPORT IN LOCALLY PERIODIC MEDIA
Authors: MOKHTAR-KHARROUBI MUSTAPHA
Published: February 2004

This paper deals with boundary value problems and spectral problems for neutron transport equations involving locally periodic (in space) collision frequencies and collision operators. We show strong convergence results to the solution of homogenized problems when the period goes to zero. The mathematical analysis relies mainly on smoothing effects of velocity averages.
THE MAIN INEQUALITY OF 3D VECTOR ANALYSIS
Authors: AUCHMUTY GILES
Published: February 2004

This paper proves some simple inequalities for Sobolev vector fields on nice bounded three-dimensional regions, subject to homogeneous mixed normal and tangential boundary data. The fields just have divergence and curl in L2. For the limit cases of prescribed zero normal, respectively zero tangential, data on the whole boundary, the inequalities were proved by Friedrichs who called the result the main inequality of vector analysis. For this mixed case, the optimal constants in the inequality are described, together with the fields for which equality holds. The detailed results depend on a special orthogonal decomposition and the analysis of associated eigenvalue problems.
ON THE QUASI-ISOTROPIC INFLATIONARY SOLUTION
Authors: IMPONENTE GIOVANNI , MONTANI GIOVANNI
Published: February 2004

In this paper we find a solution for a quasi-isotropic inflationary Universe which allows to introduce in the problem a certain degree of inhomogeneity. We consider a model which generalizes the (flat) FLRW one by introducing a first order inhomogeneous term, whose dynamics is induced by an effective cosmological constant. The 3-metric tensor is constituted by a dominant term, corresponding to an isotropic-like component, while the amplitude of the first order one is controlled by a "small" function η(t).

In a Universe filled with ultra relativistic matter and a real self-interacting scalar field, we discuss the resulting dynamics, up to first order in η, when the scalar field performs a slow roll on a plateau of a symmetry breaking configuration and induces an effective cosmological constant.

We show how the spatial distribution of the ultra relativistic matter and of the scalar field admits an arbitrary form but nevertheless, due to the required inflationary e-folding, it cannot play a serious dynamical role in tracing the process of structures formation (via the Harrison–Zeldovic spectrum). As a consequence, this paper reinforces the idea that the inflationary scenario is incompatible with a classical origin of the large scale structures.
CURVATURE QUINTESSENCE MATCHED WITH OBSERVATIONAL DATA
Authors: CAPOZZIELLO S. , CARDONE V. F. , CARLONI S. , TROISI A.
Published: February 2004

Quintessence issues can be achieved by taking into account higher order curvature invariants into the effective action of gravitational field. Such an approach is naturally related to fundamental theories of quantum gravity which predict higher order terms in loop expansion of quantum fields in curved space-times. In this framework, we obtain a class of cosmological solutions which are fitted against cosmological data. We reproduce encouraging results able to fit high redshift supernovae and WMAP observations. The age of the universe and other cosmological parameters are discussed in this context.
ELLIPTICITY ANALYSIS OF THE BOOMERanG CMB MAPS
Authors: GURZADYAN V. G. , ADE P. A. R. , De BERNARDIS P. , BIANCO C. L. , BOCK J. J. , BOSCALERI A. , CRILL B. P. , De TROIA G. , GANGA K. , GIACOMETTI M. , HIVON E. , HRISTOV V. V. , KASHIN A. L. , LANGE A. E. , MASI S. , MAUSKOPF P. D. , MONTROY T. , NATOLI P. , NETTERFIELD C. B. , PASCALE E. , PIACENTINI F. , POLENTA G. , RUHL J.
Published: February 2004

The properties of the Cosmic Microwave Background (CMB) maps carry valuable cosmological information. Here we report the results of the analysis hot and cold CMB anisotropy spots in the BOOMERanG 150 GHz map in terms of number, area, ellipticity, vs. temperature threshold. We carried out this analysis for the map obtained by summing independent measurement channels (signal plus noise map) and for a comparison map (noise only map) obtained by differencing the same channels. The anisotropy areas (spots) have been identified for both maps for various temperature thresholds and a catalog of the spots has been produced. The orientation (obliquity) of the spots is random for both maps. We computed the mean elongation of spots obtained from the maps at a given temperature threshold using a simple estimator. We found that for the sum map there is a region of temperature thresholds where the average elongation is not dependent on the threshold. Its value is ~2.3 for cold areas and ~2.2 for hot areas. This is a non-trivial result. The bias of the estimator is ≲+0.4 for areas of size ≲30′, and smaller for larger areas. The presence of noise also biases the ellipticity by ≲+0.3. These biases have not been subtracted in the results quoted above. The threshold independent and random obliquity behaviour in the sum map is stable against pointing reconstruction accuracy and noise level of the data, thus confirming that these are actual properties of the dataset. The data used here give a hint of high ellipticity for the largest spots. Analogous elongation properties of CMB anisotropies had been detected for COBE-DMR 4 year data. If this is due to geodesics mixing, it would point to a non zero curvature of the Universe.
NOTES ON THE FIDELITY OF SYMPLECTIC QUANTUM ERROR-CORRECTING CODES
Authors: HAMADA MITSURU
Published: February 2004

Two observations are given on the fidelity of schemes for quantum information processing. In the first one, we show that the fidelity of a symplectic (stabilizer) code, if properly defined, exactly equals the "probability" of the correctable errors for general quantum channels. The second observation states that for any coding rate below the quantum capacity, exponential convergence of the fidelity of some codes to unity is possible.
ENTANGLEMENT AND FRUSTRATION IN ORDERED SYSTEMS
Authors: WOLF MICHAEL M. , VERSTRAETE FRANK , IGNACIO CIRAC J.
Published: February 2004

This article reviews and extends recent results concerning entanglement and frustration in multipartite systems which have some symmetry with respect to the ordering of the particles. Starting point of the discussion are Bell inequalities: their relation to frustration in classical systems and their satisfaction for quantum states which have a symmetric extension. We then discussed how more general global symmetries of multipartite systems constrain the entanglement between two neighboring particles. We prove that maximal entanglement (measured in terms of the entanglement of formation) is always attained for the ground state of a certain nearest neighbor interaction Hamiltonian having the considered symmetry with the achievable amount of entanglement being a function of the ground state energy. Systems of Gaussian states, i.e. quantum harmonic oscillators, are investigated in more detail and the results are compared to what is known about ordered qubit systems.
INTRODUCTION TO THE BASICS OF ENTANGLEMENT THEORY IN CONTINUOUS-VARIABLE SYSTEMS
Authors: EISERT J. , PLENIO M. B.
Published: February 2004

We outline the basic questions that are being studied in any theory of entanglement. Following a brief review of some of the main achievements of entanglement theory for finite-dimensional systems such as qubits, we will then consider entanglement in infinite-dimensional systems. Asking for a theory of entanglement in such systems under experimentally feasible operations leads to the development of the theory of entanglement of Gaussian states. Results of this theory are presented and the tools that have been developed for this theory are then applied to a number of problems.
QUANTUM WALKS AND THEIR ALGORITHMIC APPLICATIONS
Authors: AMBAINIS ANDRIS
Published: February 2004

Quantum walks are quantum counterparts of Markov chains. In this article, we give a brief overview of quantum walks, with emphasis on their algorithmic applications.
ANOMALOUS QUANTUM STATES IN FINITE MACROSCOPIC SYSTEMS
Authors: SHIMIZU AKIRA , MIYADERA TAKAYUKI , UKENA AKIHISA
Published: February 2004

We consider finite macroscopic systems, i.e. systems of large but finite degrees of freedom, which we believe are poorly understood as compared with small systems and infinite systems. We focus on pure states that do not have the "cluster property". Such a pure state is entangled macroscopically, and is quite anomalous in view of many-body physics because it does not approach any pure state in the infinite-size limit. However, we often encounter such anomalous states when studying finite macroscopic systems, such as quantum computers with many qubits and finite systems that will exhibit symmetry breaking in the infinite-size limit. We study stabilities of such anomalous states in general systems. In contrast to the previous works, we obtain general and universal results, by making full use of the locality of the theory. Using the general results, we discuss roles of anomalous states in quantum computers, and the mechanism of emergence of a classical world from quantum theory.
UNCERTAINTY PRINCIPLE FOR QUANTUM INSTRUMENTS AND COMPUTING
Authors: OZAWA MASANAO
Published: February 2004

The notion of quantum instruments is formalized as statistical equivalence classes of all the possible quantum measurements and mathematically characterized as normalized completely positive map valued measures under naturally acceptable axioms. Recently, universally valid uncertainty relations have been established to set a precision limit for any instruments given a disturbance constraint in a form more general than the one originally proposed by Heisenberg. One of them leads to a quantitative generalization of the Wigner–Araki–Yanase theorem on the precision limit of measurements under conservation laws. Applying this, a rigorous lower bound is obtained for the gate error probability of physical implementations of Hadamard gates on a standard qubit of a spin 1/2 system by interactions with control fields or ancilla systems obeying the angular momentum conservation law.
An LQT mutant minK alters KvLQT1 trafficking
Authors: Krumerman Andrew , Gao Xiaohong , Bian Jin-Song , Melman Yonathan F. , Kagan Anna , McDonald Thomas V.
Published: February 2004

Cardiac IKs, the slowly activated delayed-rectifier K+ current, is produced by the protein complex composed of α- and β-subunits: KvLQT1 and minK. Mutations of genes encoding KvLQT1 and minK are responsible for the hereditary long QT syndrome (loci LQT1 and LQT5, respectively). MinK-L51H fails to traffic to the cell surface, thereby failing to produce effective IKs. We examined the effects that minK-L51H and an endoplasmic reticulum (ER)-targeted minK (minK-ER) exerted over the electrophysiology and biosynthesis of coexpressed KvLQT1. Both minK-L51H and minK-ER were sequestered primarily in the ER as confirmed by lack of plasma membrane expression. Glycosylation and immunofluorescence patterns of minK-L51H were qualitatively different for minK-ER, suggesting differences in trafficking. Cotransfection with the minK mutants resulted in reduced surface expression of KvLQT1 as assayed by whole cell voltage clamp and immunofluorescence. MinK-L51H reduced current amplitude by 91% compared with wild-type (WT) minK/KvLQT1, and the residual current was identical to KvLQT1 without minK. The phenotype of minK-L51H on IKs was not dominant because coexpressed WT minK rescued the current and surface expression. Collectively, our data suggest that ER quality control prevents minK-L51H/KvLQT1 complexes from trafficking to the plasma membrane, resulting in decreased IKs. This is the first demonstration that a minK LQT mutation is capable of conferring trafficking defects onto its associated α-subunit.
Potassium currents regulating secretion from Brunner's glands in guinea pig duodenum
Authors: Kovac Jason , Moore Beverley , Vanner Stephen
Published: February 2004

This study examined the role of outward K+currents in the acinar cells underlying secretion from Brunner's glands in guinea pig duodenum. Intracellular recordings were made from single acinar cells in intact acini in in vitro submucosal preparations, and videomicroscopy was employed in the same preparation to correlate these measures with secretion. Mean resting membrane potential was -74 mV and was depolarized by high external K+(20 mM) and the K+channel blockers 4-aminopyridine (4-AP), quinine, and clotrimazole. The cholinergic agonist carbachol (60–2,000 nM; EC50= 200 nM) caused a concentration-dependent initial hyperpolarization of the membrane and an associated decrease in input resistance. This hyperpolarization was significantly decreased by 20 mM external K+or membrane hyperpolarization and increased by 1 mM external K+or membrane depolarization. It was blocked by the K+channel blockers tetraethylammonium (TEA), 4-AP, quinine, and clotrimazole but not iberiotoxin. When videomicroscopy was employed to measure dilation of acinar lumen in the same preparation, carbachol-evoked dilations were altered in a parallel fashion when external K+was altered. The dilations were also blocked by the K+channel blockers TEA, 4-AP, quinine, and clotrimazole but not iberiotoxin. These findings suggest that activation of outward K+currents is fundamental to the initiation of secretion from these glands, consistent with the model of K+efflux from the basolateral membrane providing the driving force for secretion. The pharmacological profile suggests that these K+channels belong to the intermediate conductance group.
Hepcidin regulation of ferroportin 1 expression in the liver and intestine of the rat
Authors: Yeh Kwo-yih , Yeh Mary , Glass Jonathan
Published: February 2004

Hepcidin has been implicated as the iron stores regulator: a hepatic signaling molecule that regulates intestinal iron absorption by undefined mechanisms. The possibility that hepcidin regulates the expression of ferroportin 1 (FPT1), the basolateral iron transporter, was examined in rats after administration of LPS, an iron chelator, or His-tagged recombinant hepcidin (His-rHepc). In the liver, LPS stimulated a biphasic increase of hepcidin mRNA with peaks of mRNA at 6 and 36 h. Concurrently, hepatic FPT1 mRNA expression decreased to minimal level at 6 h and then increased with a peak at 24–36 h. LPS also induced biphasic changes in intestinal FPT1 mRNA expression, with decreased levels at 6 h and increased expression at 48 h. Whereas the initial decrease of FPT1 coincides with an LPS-induced decrease in serum iron, both intestinal and hepatic FPT1 expression recovered, whereas serum iron concentration continued to decrease for at least 24 h. Dietary iron ingestion increased intestinal ferritin protein production but did not reduce intestinal FPT1 mRNA expression. The iron chelator pyrrolidinedithiocarbamate (PDTC) stimulated hepatic hepcidin without suppressing intestinal FPT1 expression. In PDTC-treated rats, LPS stimulated no additional hepatic hepcidin expression but did increase intestinal FPT1 expression. Administration of HisrHepc induced significant reduction of intestinal FPT1 expression. Taken together, these data suggest that hepcidin mediates LPS-induced downregulation of intestinal FPT1 expression and that the hepcidin signaling pathway involves a PDTC-sensitive step.
Expression of P2Y nucleotide receptors and ectonucleotidases in quiescent and activated rat hepatic stellate cells
Authors: Dranoff Jonathan A. , Ogawa Mika , Kruglov Emma A. , Gaça Marianna D. A. , Sévigny Jean , Robson Simon C. , Wells Rebecca G.
Published: February 2004

Extracellular nucleotides regulate a variety of cellular activities, including proliferation of fibrogenic cells outside of the liver. However, the expression of receptors for extracellular nucleotides in hepatic stellate cells (HSC) is unknown. Thus our aims were to investigate the expression of mediators of nucleotide signaling in HSC and to determine whether extracellular nucleotides regulate HSC function. Confocal video microscopy was used to observe nucleotide-induced changes in cytosolic Ca2+ (Cai2+) in live HSC. P2Y receptor subtype expression and ectonucleotidase expression in quiescent and activated HSC were determined using RT-PCR, Northern blot, immunoblot, and confocal immunofluorescence. Functional ectonucleotidase activity was assessed using a colorimetric method. Nucleotide-sensitive procollagen-1 mRNA expression in activated HSC was assessed using real-time RT-PCR. Extracellular ATP increased Cai2+ in HSC; this was inhibited by the P2 receptor inhibitor suramin. Quiescent HSC expressed the P2Y subtypes P2Y2 and P2Y4 and were activated by ATP and UTP, whereas activated HSC expressed the P2Y subtype P2Y6 and were activated by UDP and ATP. Activated but not quiescent HSC expressed the ectonucleotidase nucleoside triphosphate diphosphohydrolase 2, extracellular UDP tripled procollagen-1 mRNA expression in activated HSC, and this was inhibited by the P2Y receptor inhibitor suramin. HSC express functional P2Y receptors and switch the expression of P2Y receptor subtypes on activation. Moreover, HSC differentially regulate nucleoside triphosphate diphosphohydrolase expression after activation. Because activation of P2Y receptors in activated HSC regulates procollagen-1 transcription, P2Y receptors may be an attractive target to prevent or treat liver fibrosis.
Indicial response functions of growth and remodeling of common bile duct postobstruction
Authors: Dang Quang , Gregersen Hans , Duch Birgitte , Kassab Ghassan S.
Published: February 2004

Biliary duct obstruction is an important clinical condition that stems from cholelithiasis, the neoplasm in the wall or, most commonly, gallbladder stones. The objective of this study is to understand the structural and mechanical remodeling of the common bile duct (CBD) postobstruction. Porcine CBD was ligated near the duodenum that increased the duct's pressure from 6.4 to 18.3 cmH2O in the first 12 h and to 30.7 cmH2O after 32 days. The remodeling process was studied after 3 h, 12 h, 2 days, 8 days, and 32 days ( n = 5 in each group) after obstruction. One additional animal in each group was sham operated. At each scheduled time, the time course of change of morphometry (diameter, length, wall thickness, etc.) and mechanical properties (stress, strain, etc.) was documented. It was found that the diameter increased by about threefold and the wall thickness of the CBD doubled in the 32-day group compared with the sham group ( P < 0.001). The stress and strain increased initially with increase in pressure but recovered to near the control values by day 32 due to the structural and mechanical adaptations. Hence, the net effect of the structural and mechanical remodeling is to restore the stress and strain to their homeostatic values. Furthermore, the strain recovers more rapidly and more completely than stress. Finally, the remodeling data were expressed mathematically in terms of indicial response functions (IRF), i.e., change of a particular feature of a CBD in response to a unit step change of the pressure. The IRF approach provides a quantitative description of the remodeling process in the CBD.
Functional importance of ICAM-1 in the mechanism of neutrophil-induced liver injury in bile duct-ligated mice
Authors: Gujral Jaspreet S. , Liu Jie , Farhood Anwar , Hinson Jack A. , Jaeschke Hartmut
Published: February 2004

Cholestasis-induced liver injury during bile duct obstruction causes an acute inflammatory response. To further characterize the mechanisms underlying the neutrophil-induced cell damage in the bile duct ligation (BDL) model, we performed experiments using wild-type (WT) and ICAM-1-deficient mice. After BDL for 3 days, increased ICAM-1 expression was observed along sinusoids, along portal veins, and on hepatocytes in livers of WT animals. Neutrophils accumulated in sinusoids [358 ± 44 neutrophils/20 high-power fields (HPF)] and >50% extravasated into the parenchymal tissue. Plasma alanine transaminase (ALT) levels increased by 23-fold, and severe liver cell necrosis (47 ± 11% of total cells) was observed. Chlorotyrosine-protein adducts (a marker for neutrophil-derived hypochlorous acid) and 4-hydroxynonenal adducts (a lipid peroxidation product) were detected in these livers. Neutrophils also accumulated in the portal venules and extravasated into the portal tracts. However, no evidence for chlorotyrosine or 4-hydroxynonenal protein adducts was detected in portal tracts. ICAM-1-deficient mice showed 67% reduction in plasma ALT levels and 83% reduction in necrosis after BDL compared with WT animals. The total number of neutrophils in the liver was reduced (126 ± 25/20 HPF), and 85% of these leukocytes remained in sinusoids. Moreover, these livers showed minimal staining for chlorotyrosine and 4-hydroxynonenal adducts, indicating a substantially reduced oxidant stress and a diminished cytokine response. Thus neutrophils relevant for the aggravation of acute cholestatic liver injury in BDL mice accumulate in hepatic sinusoids, extravasate into the tissue dependent on ICAM-1, and cause cell damage involving reactive oxygen formation.
Antioxidant activity of nitro derivative of aspirin against ischemia-reperfusion in hamster cheek pouch microcirculation
Authors: Bertuglia Silvia , Giusti Andrea , Del Soldato Piero
Published: February 2004

Aspirin that has been chemically combined with a nitric oxide (NO) donor (NCX-4016) has been shown to inhibit cyclooxygenase and prostaglandin generation while maintaining the inhibitory effects of aspirin. The possible role of reactive oxygen species (ROS) in the action of NCX-4016 in ischemia-reperfusion (I/R) has not been studied. Furthermore, we were interested in comparing the effects of a conventional NO donor [2,2′-hydroxynitrosohydrazino-bis-etanamine (DETA/NO)] and NCX-4016 at the microvascular level in the hamster cheek pouch visualized by using an intravital fluorescent microscopy technique. Microvascular injury was assessed by measuring diameter change, the perfused capillary length (PCL), and leukocyte adhesion. Animals were treated with NCX-4016 (100 mg/kg or 30 mg·kg-1·day-1 for 5 days po) or DETA-NO (0.5 mg/kg). Mean arterial blood pressure increased slightly but significantly after NCX-4016 treatment. During 5- and 15-min reperfusion, lipid peroxides in the systemic blood increased by 72 and 89% vs. baseline, respectively, and were still higher than in basal conditions after 30-min reperfusion in the I/R group. Pretreatment with NCX-4016 maintained ROS at normal levels; increased arteriolar diameter, blood flow, and PCL; and decreased leukocyte adhesion ( P < 0.05). DETA-NO decreased ROS during 30-min reperfusion; however, later there was a significant increase during reperfusion. DETA-NO decreased leukocyte adhesion ( P < 0.05) but microvascular permeability increased after 30 min of reperfusion. In conclusion, NCX-4016 attenuates oxidative stress and prevents arteriolar constriction during I/R, whereas DETA-NO increases lipid peroxides in the systemic blood and permeability after reperfusion.
Inducible antisense RNA targeting amino acid transporter ATB0/ASCT2 elicits apoptosis in human hepatoma cells
Authors: Fuchs Bryan C. , Perez J. Christian , Suetterlin Julie E. , Chaudhry Sofia B. , Bode Barrie P.
Published: February 2004

Amino acid transporter B0/ASC transporter 2 (ATB0/ASCT2) is responsible for most glutamine uptake in human hepatoma cells. Because this transporter is not expressed in normal hepatocytes, we hypothesized that its expression is necessary for growth of human liver cancer cells. To test this hypothesis, Sloan Kettering hepatoma (SK-Hep) cells were stably transfected with an inducible 1.3-kb ATB0/ASCT2 antisense RNA expression plasmid under the transcriptional control of mifepristone, a synthetic steroid. Induced antisense RNA expression in monolayer cultures decreased ATB0/ASCT2 mRNA levels by 73% and glutamine transport rates by 65% compared with controls after 24 h, leading to a 98% decrease in cell number after 48 h. Cellular death was attributable to apoptosis based on cellular blebbing, caspase-3 activation, vital dye and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, and poly-(ADP-ribose) polymerase (PARP) cleavage. Transporter knockdown also markedly increased activities of caspases-2 and -9, marginally enhanced caspase-8 activity, and dramatically increased ASCT1 mRNA levels, presumably as a futile compensatory response. Apoptosis elicited via transporter silencing was not attributable to the double-stranded RNA-dependent protein kinase R (PKR) pathway. For comparison, glutamine deprivation also caused apoptotic cell death but with slower temporal kinetics, stimulated caspases-2 and -3 but not caspases-8 or -9 activities, and led to considerable PARP cleavage. Thus ASCT2 suppression exerts proapoptotic effects transcending those of glutamine starvation alone. We conclude that ATB0/ASCT2 expression is necessary for SK-Hep cell growth and viability and suggest that it be further explored as a selective target for human hepatocellular carcinoma.
Gender differences in small intestinal endothelial function: inhibitory role of androgens
Authors: Ba Zheng F. , Yokoyama Yukihiro , Toth Balazs , Rue Loring W. , Bland Kirby I. , Chaudry Irshad H.
Published: February 2004

Although gender differences exist in cardiovascular endothelial function, it remains unclear whether such differences are also seen in small intestinal endothelial function. To determine this, untreated male, age-matched proestrus female, castrated male, and 17β-estradiol (E2)-treated noncastrated male rats were studied. Dose response curves to ACh and nitroglycerin (NTG) were determined by measuring changes in perfusion pressure by using an isolated small intestinal perfusion model. Endothelium-derived nitric oxide (NO) production/release was indirectly determined by the ability of intact endothelium to suppress serotonin (10-5M)-induced perfusion pressure changes. Intestinal tissue levels of NO were also measured. Moreover, plasma levels of androgen and E2 were determined and correlated with ACh (10-8M)-induced perfusion pressure reductions. ACh-induced intestinal perfusion pressure reductions in proestrus females, castrated males, and E2-treated noncastrated males were significantly higher than in untreated males. NTG-induced perfusion pressure reductions were not significantly different among groups. Perfusion pressures after administration of serotonin (10-5M) and intestinal tissue levels of NO in proestrus females, castrated males, and E2-treated noncastrated males were also significantly higher than in untreated males. Plasma androgen levels in proestrus females, castrated males, and in E2-treated noncastrated males were significantly lower compared with untreated males. There was a positive correlation between plasma androgen and ACh-reduced perfusion pressure; however, E2 levels did not show a similar relationship. Thus androgens appear to play an inhibitory role in small intestinal endothelial function. These properties in male vessels can be modulated by decreasing the level of circulating androgens or by E2 treatment.
Expression and functional contribution of hTHTR-2 in thiamin absorption in human intestine
Authors: Said Hamid M. , Balamurugan Krishnaswamy , Subramanian Veedamali S. , Marchant Jonathan S.
Published: February 2004

The aim of this study was to investigate expression and relative contribution of human thiamin transporter (hTHTR)-2 toward overall carrier-mediated thiamin uptake by human intestinal epithelial cells. Northern blot analysis showed that the message of the hTHTR-2 is expressed along the native human gastrointestinal tract with highest expression being in the proximal part of small intestine. hTHTR-2 protein was found, by Western blot analysis, to be expressed at the brush-border membrane (BBM), but not at the basolateral membrane, of native human enterocytes. This pattern of expression was confirmed in studies using a fusion protein of hTHTR-2 with the enhanced green fluorescent protein (hTHTR2-EGFP) expressed in living Caco-2 cells grown on filter. Pretreating Caco-2 cells (which also express the hTHTR-2 at RNA and protein levels) with hTHTR-2 gene-specific small interfering RNA (siRNA) led to a significant ( P < 0.01) and specific inhibition (48%) in carrier-mediated thiamin uptake. Similarly, pretreating Caco-2 cells with siRNA that specifically target hTHTR-1 (which is expressed in Caco-2 cells) also significantly ( P < 0.01) and specifically inhibited (by 56%) carrier-mediated thiamin uptake. When Caco-2 cells were pretreated with siRNAs against both hTHTR-2 and hTHTR-1 genes, an almost complete inhibition in carrier-mediated thiamin uptake was observed. These results show that the message of hTHTR-2 is expressed along the human gastrointestinal tract and that expression of its protein in intestinal epithelia is mainly localized to the apical BBM domain. In addition, results show that this transporter plays a significant role in carrier-mediated thiamin uptake in human intestine.
Low-dose PGE2mimics the duodenal secretory response to luminal acid in mice
Authors: Hirokawa Masahiko , Furukawa Osamu , Guth Paul H. , Engel Eli , Kaunitz Jonathan D.
Published: February 2004

Luminal exposure to concentrated acid, the most accepted physiological stimulus for duodenal bicarbonate secretion (DBS), cannot be used with in vitro preparations due to potential tissue damage. We thus examined whether exposure to PGE2, a well-characterized physiological duodenal secretagogue, could mimic the effects of acid perfusion. DBS was measured in C57/BL mice by pH-stat/back-titration and measurement of total dissolved CO2concentration ([CO2]t). Anion transport inhibitor DIDS, anion channel inhibitor 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), carbonic anhydrase inhibitor methazolamide, and nonselective cyclooxygenase inhibitor indomethacin were used to inhibit separate components of HCO3−secretory pathway. Baseline DBS was not altered by exposure to methazolamide (0.1 mM) but was slightly reduced by DIDS (0.5 mM). DBS and [CO2]tincreased after acid and PGE2exposure. DIDS (0.5 mM) and NPPB (0.2 mM) abolished acid-induced DBS increase. Methazolamide (0.1 mM) and DIDS inhibited acid-induced [CO2]tincrease. DIDS, NPPB, or methazolamide had little effect on DBS in response to high concentration PGE2(100 μg/ml). Low concentration PGE2(1 μg/ml) increased DBS that was inhibited by DIDS, NPPB, and methazolamide. Pretreatment with indomethacin (5 mg/kg) inhibited DBS induced by acid exposure but not by PGE2. High-dose PGE2substantially increases DBS by a mechanism that appears to be different than secretory response to luminal acid perfusion. Secretory response to low-dose PGE2, at least in terms of inhibitor profile, closely resembles secretion in response to perfusion of physiological acid concentrations and may be a useful stimulus for in vitro study of DBS in isolated mouse duodenum.
New technique for measurement of left ventricular pressure in conscious mice
Authors: Ishizaka Shinji , Sievers Richard E. , Zhu Bo-Qing , Rodrigo Manoj C. , Joho Shuji , Foster Elyse , Simpson Paul C. , Grossman William
Published: February 2004

Concern about the effects of anesthesia on physiological measurements led us to develop methodology to assess left ventricular (LV) pressure in conscious mice. Polyethylene-50 tubing filled with heparinized saline was implanted in the LV cavity through its apex via an abdominal approach and exteriorized to the back of the animal. This surgery was done under anesthesia with either an intraperitoneal injection of ketamine (80 mg/kg) and xylazine (5 mg/kg) (K+X) in 11 mice or isoflurane (ISF; 1.5 vol%) by inhalation in 14 mice. Postoperatively, mice were trained daily to lie quietly head first in a plastic cone. LV pressure, the first derivative of LV pressure (dP/d t), and heart rate (HR) in the conscious state were compared between the two groups at 3 days and 1 wk after recovery from surgery using a 1.4-Fr Millar catheter inserted into the LV through the tubing, with the mice lying quietly in the plastic cone. Acutely during anesthesia, K+X decreased HR (from 698 to 298 beats/min), LV systolic pressure (from 107 to 65 mmHg), and maximal dP/d t (dP/d tmax) (from 15,724 to 4,445 mmHg/s), all P < 0.01. Similar but less marked negative chronotropic and inotropic effects were seen with ISF. HR and dP/d tmax were decreased significantly in K+X mice 3 days after surgery compared with those anesthetized with ISF (655 vs. 711 beats/min, P < 0.05; 14,448 vs. 18,048 mmHg/s, P < 0.001) but increased to the same level as in ISF mice 1 wk after surgery. In ISF mice, recovery of function occurred rapidly and there were no differences in LV variables between 3 days and 1 wk. LV pressure and dP/d t can be measured in conscious mice with a micromanometer catheter inserted through tubing implanted permanently in the LV apex. Anesthesia with either K+X or, to a lesser extent, ISF, depressed LV function acutely. This depression of function persisted for 3 days after surgery with K+X (but not ISF) and did not recover completely until 1 wk postanesthesia.