bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutated Form of the Newcastle Disease Virus Hemagglutinin-Neuraminidase Interacts with the Homologous Fusion Protein despite Deficiencies in both Receptor Recognition and Fusion Promotion
Authors: Li Jianrong , Quinlan Edward , Mirza Anne , Iorio Ronald M. 
Published: April 2004

ABSTRACT
The Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) protein mediates attachment to cellular receptors. The fusion (F) protein promotes viral entry and spread. However, fusion is dependent on a virus-specific interaction between the two proteins that can be detected at the cell surface by a coimmunoprecipitation assay. A point mutation of I175E in the neuraminidase (NA) active site converts the HN of the Australia-Victoria isolate of the virus to a form that can interact with the F protein despite negligible receptor recognition and fusion-promoting activities. Thus, I175E-HN could represent a fusion intermediate in which HN and F are associated and primed for the promotion of fusion. Both the attachment and fusion-promoting activities of this mutant HN protein can be rescued either by NA activity contributed by another HN protein or by a set of four substitutions at the dimer interface. These substitutions were identified by the evaluation of chimeras composed of segments from HN proteins derived from two different NDV strains. These findings suggest that the I175E substitution converts HN to an F-interactive form, but it is one for which receptor binding is still required for fusion promotion. The data also indicate that the integrity of the HN dimer interface is critical to its receptor recognition activity.
Nef Binds p6* in GagPol during Replication of Human Immunodeficiency Virus Type 1
Authors: Costa Luciana J. , Zheng Yong-Hui , Sabotic Jerica , Mak Johnson , Fackler Oliver T. , Peterlin B. Matija 
Published: April 2004

ABSTRACT

The atypical Nef protein (NefF12) from human immunodeficiency virus type 1 strain F12 (HIV-1
F12
) interferes with virion production and infectivity via a mysterious mechanism. The correlation of these effects with the unusual perinuclear subcellular localization of NefF12 suggested that the wild-type Nef protein could bind to assembly intermediates in late stages of viral replication. To test this hypothesis, Nef from HIV-1
NL4-3
was fused to an endoplasmic reticulum (ER) retention signal (NefKKXX). This mutant NefKKXX protein recapitulated fully the effects of NefF12 on Gag processing and virion production, either alone or as a CD8 fusion protein. Importantly, the mutant NefKKXX protein also localized to the intermediate compartment, between the ER and the trans-Golgi network. Furthermore, Nef bound the GagPol polyprotein in vitro and in vivo. This binding mapped to the C-terminal flexible loop in Nef and the transframe p6* protein in GagPol. The significance of this interaction was demonstrated by a genetic assay in which the release of a mutant HIV-1 provirus lacking the PTAP motif in the late domain that no longer binds Tsg101 was rescued by a Nef.Tsg101 chimera. Importantly, this rescue as well as incorporation of Nef into HIV-1 virions correlated with the ability of Nef to interact with GagPol. Our data demonstrate that the retention of Nef in the intermediate compartment interferes with viral replication and suggest a new role for Nef in the production of HIV-1.
Characterization of Restrictions to Human Immunodeficiency Virus Type 1 Infection of Monocytes
Authors: Triques Karine , Stevenson Mario 
Published: April 2004

ABSTRACTTissue macrophages are an important cellular reservoir for replication of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus. In vitro, the ability of macrophages to support viral replication is differentiation dependent in that precursor monocytes are refractory to infection. There is, however, no consensus as to the exact point at which infection is restricted in monocytes. We have revisited this issue and have compared the efficiencies of early HIV-1 replication events in monocytes and in differentiated macrophages. Although virus entry in monocytes was comparable to that in differentiated macrophages, synthesis of full-length viral cDNAs was very inefficient. Relative to differentiated macrophages, monocytes contained low levels of dTTP due to low thymidine phosphorylase activity. Exogenous addition ofd-thymidine increased dTTP levels to that in differentiated macrophages but did not correct the reverse transcription defect. These results point to a restriction in monocytes that is independent of reverse transcription precursors and suggest that differentiation-dependent cellular cofactors of reverse transcription are rate limiting in monocytes.
Polymer Nanocomposites for Aerospace Applications: Fabrication
Authors: Njuguna J. , Pielichowski K. 
Published: April 2004

AbstractNanocomposite polymers have tremendous potential to enhance the performance of macromolecular materials used for composite matrices. Effective utilization of carbon nanotubes in composite applications depends strongly on the ability to homogeneously disperse them throughout the matrix without destroying their integrity. This work looks at the fabrication for montmorillonite, fullerenes and nanotubes polymer/nanocomposites tailored to fit aerospace needs. Further insight is also given on developments in nanofibers and nanotubes production for good load transfer on the composite systems.
Application of different kinetic models to analyze the reaction rates of liquid crystalline homopolyesters
Authors: Al‐Adwani H. , Bishara A. E. , Al‐Roomi Y. , Mathew J. , Shaban H. I. 
Published: April 2004

AbstractKinetics of homopolyesterification between methyl hydroquinone diacetate (MHQDA) and 1,4‐naphthalene dicarboxylic acid (1,4‐NDCA) in the melt were analyzed using three different rate models. The three different techniques used to evaluate the kinetic parameters for the homopolymerization reaction were as follows: simple second‐order textbook equation, a simple second‐order kinetic model, and Mathew's model. A simple second‐order reaction mechanism previously reported by Mathew et al. is found to summarize the catalyzed and uncatalyzed reactions between MHQDA and 1,4‐NDCA. Close comparison was obtained between the experimental and theoretical data by using the Mathew's model. Mathew's model was found to perfectly fit the experimental data. The kinetic analysis of the studied system reveals the implicit simplicity of complex systems. The percentage error for the fit was found to be <5% for the Mathew's model. These novel homopolymers were analyzed for their thermal properties by using a differential scanning calorimeter. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1118–1128, 2004
Probing the Proteolytic Stability of β‐Peptides Containing α‐Fluoro‐ and α‐Hydroxy‐β‐Amino Acids
Authors: Hook David F. , Gessier François , Noti Christian , Kast Peter , Seebach Dieter 
Published: April 2004

AbstractOne of the benefits of β‐peptides as potential candidates for biological applications is their stability against common peptidases. Attempts have been made to rationalize this stability by altering the electron availability of a given amide carbonyl bond through the introduction of polar substituents at the α‐position of a single β‐amino acid. Such β‐amino acids (β‐homoglycine, β‐homoalanine), containing one or two fluorine atoms or a hydroxy group in the α‐position, were prepared in enantiopure form. A versatile method for preparing these α‐fluoro‐β‐amino acids by the homologation of appropriate α‐amino acids and C‐OH→C‐F or CO→CF2 substitution with DAST, is described. Consequently, a series of β‐peptides possessing an electronically modified residue at the N terminus or embedded within the chain was synthesized, and their proteolytic stability was investigated against a selection of enzymes. All ten β‐peptides tested were resilient to proteolysis. Introducing a polar, sterically undemanding group, into the α‐position of β‐amino acids in a β‐peptide chain does not appear to facilitate localized or general enzymatic degradation.
Enzymatic Fluorination in Streptomyces cattleya Takes Place with an Inversion of Configuration Consistent with an SN2 Reaction Mechanism
Authors: Cadicamo Cosimo D. , Courtieu Jacques , Deng Hai , Meddour Abdelkrim , O'Hagan David 
Published: April 2004

AbstractThe stereochemical course of the recently isolated fluorination enzyme from Streptomyces cattleya has been evaluated. The enzyme mediates a reaction between the fluoride ion and S‐ adenosyl‐L‐methionine (SAM) to generate 5′‐fluoro‐5′‐deoxyadenosine (5′‐FDA). Preparation of (5′R)‐[5‐2H1]‐ATP generated (5′R)‐[5‐2H1]‐5′‐FDA in a coupled enzyme assay involving SAM synthase and the fluorinase. The stereochemical analysis of the product relied on 2H NMR analysis in a chiral liquid‐crystalline medium. It is concluded that the enzyme catalyses the fluorination with an inversion of configuration consistent with an SN2 reaction mechanism.
Experimental Measurement of Noncovalent Interactions Between Halogens and Aromatic Rings
Authors: Adams Harry , Cockroft Scott L. , Guardigli Claudio , Hunter Christopher A. , Lawson Kevin R. , Perkins Julie , Spey Sharon E. , Urch Christopher J. , Ford Rhonan 
Published: April 2004

AbstractChemical double mutant cycles have been used to quantify the interactions of halogens with the faces of aromatic rings in chloroform. The halogens are forced over the face of an aromatic ring by an array of hydrogen‐bonding interactions that lock the complexes in a single, well‐defined conformation. These interactions can also be engineered into the crystal structures of simpler model compounds, but experiments in solution show that the halogen–aromatic interactions observed in the solid state are all unfavourable, regardless of whether the aromatic rings contain electron‐withdrawing or electron‐donating substituents. The halogen–aromatic interactions are repulsive by 1–3 kJ mol−1. The interactions with fluorine are slightly less favourable than with chlorine and bromine.
The Role of Binding Constants in the Efficiency of Chiral Catalysts Immobilized by Electrostatic Interactions: The Case of Azabis(oxazoline)–Copper Complexes
Authors: Fraile José M. , García José I. , Herrerías Clara I. , Mayoral José A. , Reiser Oliver , Socuéllamos Antonio , Werner Heiko 
Published: April 2004

AbstractAs shown by theoretical calculations, azabis(oxazoline)–copper complexes are considerably more stable than the analogous bis(oxazoline)–copper complexes. This enhanced stability allows them to be efficiently immobilized by means of electrostatic interactions to different anionic supports, such as clays and nafion–silica nanocomposites, without the loss of a ligand, as is observed for bis(oxazolines). As a result, enantioselectivities of around 90 % ee are obtained in the cyclopropanation reaction between styrene and ethyl diazoacetate. Moreover, the solid catalyst is easily recoverable.
Automatisierung in der Mikroreaktionstechnik: Das AuMμRes‐System
Authors: Löbbecke S. , Ferstl W. , Lohf A. , Steckenborn A. , Hassel J. , Häberl M. , Schmalz D. , Muntermann H. , Bayer T. , Kinzl M. , Leipprand I. 
Published: April 2004

AbstractNo abstracts.
Chemical Synthesis in Micro Reactors
Authors: Watts P. 
Published: April 2004

AbstractThis article reviews the current applications of micro reactors in the field of combinatorial chemistry and discusses how the methodology could be applied to drug discovery. Liquid phase reactions have been used to illustrate the advantages of performing chemical reactions in micro reactors which illustrate that reactions can be performed very rapidly in high conversion to enable the preparation of combinatorial libraries of structurally related compounds.
The radon transform: A new scheme for fast multidimensional NMR
Authors: Kupče Eriks , Freeman Ray 
Published: April 2004

AbstractMultidimensional nuclear magnetic resonance (NMR) spectra are used widely for structure elucidation of molecules of biochemical interest, particularly proteins, but the existing methodology is severely hampered by the long duration of the measurement, often many days. Here, we show that the inverse Radon transform can be used to reconstruct such a spectrum from a small number of different plane projections. This “projection‐reconstruction” (PR) technique reduces the time required to perform a three‐dimensional experiment by an order of magnitude and four‐dimensional spectra by two orders of magnitude, greatly extending the scope of such investigations. We show the application of the inverse Radon transform to reconstruct the four‐dimensional NMR spectrum of the nuclease A inhibitor, a measurement completed in only 35 min. This new technique is expected to have wide implications for investigations of protein structure and dynamics, currently a very active field of research. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 22A: 4–11, 2004.
Pathologic evaluation of radical cystectomy specimens
Authors: Herr Harry W. , Faulkner James R. , Grossman H. Barton , Crawford E. David 
Published: April 2004

AbstractBACKGROUNDThe authors evaluated the pathology of radical cystectomy and pelvic lymph node specimens from patients with bladder carcinoma who were enrolled in a cooperative group trial. Their objective was to determine whether current practices conform to suggested pathology practice guidelines for reporting on radical cystectomy and pelvic lymph node specimens.METHODSOverall, 268 patients underwent radical cystectomy with pelvic lymph node dissection over 11 years in a total of 109 diverse geographic locations and types of institutions. Institutions included 50 community hospitals, 36 academic hospitals, and 23 Veterans Administration (VA)/military hospitals, which evaluated 84, 137, and 47 patients, respectively. The quality of pathology examination was assessed based on the original pathology reports of specimens that were submitted according to published practice guidelines.RESULTSAmong all types of institutions, pathologic evaluation of radical cystectomy specimens generally was complete for tumor histology, grade, size, location, pathologic stage, lymph node status, prostate involvement, and associated mucosal abnormalities, including ureters and urethra. Perivesical fat (soft tissue) margins were not recorded in 10% of specimens, and 18% of patients did not mention either the presence or the number of lymph nodes. These deficiencies were observed primarily at community and VA hospitals.CONCLUSIONSThe overall quality of pathologic examination of radical cystectomy specimens is high. Better reporting of soft tissue margin status and pelvic lymph node counts is needed to achieve compliance with the standards published by evolving practice protocols. Standardized pathologic evaluation and reporting of radical cystectomy specimens will optimize important prognostic information and foster better communication between the pathologist, surgeon, and interested oncologists to benefit patients. Cancer 2004. © 2004 American Cancer Society.
Regioselective SN2 Opening of Vinylic Epoxides with Trialkylzincates and Trialkylaluminates
Authors: Equey Olivier , Vrancken Emmanuel , Alexakis Alexandre 
Published: April 2004

AbstractThe use of trialkylorganozincates and tetraalkylaluminates allows regioselective SN2 nucleophilic opening of vinylic epoxides. The reaction occurs with an anti‐substitution pattern and can be applied to a wide range of substrates. We also show that the solvent and the structure of the epoxide have an influence on the substitution products’ ratio. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Transgenic Cre expression mice for generation of erythroid‐specific gene alterations
Authors: Peterson Kenneth R. , Fedosyuk Halyna , Zelenchuk Lesya , Nakamoto Betty , Yannaki Evangelia , Stamatoyannopoulos George , Ciciotte Steven , Peters Luanne L. , Scott Linda M. , Papayannopoulou Thalia 
Published: April 2004

AbstractSummary: Transgenic mice that express Cre recombinase in erythroid cell lineages were developed so that genes affecting erythropoiesis/hematopoiesis may be altered without necessarily affecting fetus viability. A micro‐LCR cassette‐β‐globin promoter‐Cre recombinase gene (μLCR‐βpr‐Cre) construct was synthesized and used to generate transgenic mice. Concurrently, we produced mice containing a μLCR‐loxP‐flanked β sickle gene (μLCR‐loxP‐βS‐loxP) construct. μLCR‐βpr‐Cre mice with intact transgenes in variable copy number were identified. Cre expression was assessed by RNAse protection and RT‐PCR. Cre function was ascertained by breeding to μLCR‐loxP‐βS‐loxP mice. We demonstrate that βS expression was not detected in the blood of bigenics, but the gene was present in nonerythroid cells. Thus, excision of the loxP‐flanked βS gene was restricted to erythroid cell lineages. genesis 39:1–9, 2004. © 2004 Wiley‐Liss, Inc.
Essential roles of BMPR‐IA signaling in differentiation and growth of hair follicles and in skin tumorigenesis
Authors: Ming Kwan Kin , Li Allen G. , Wang Xiao‐Jing , Wurst Wolfgang , Behringer Richard R. 
Published: April 2004

AbstractSummary: Hair differentiation and growth are controlled by complex reciprocal signaling between epithelial and mesenchymal cells. To better understand the requirement and molecular mechanism of BMP signaling in hair follicle development, we performed genetic analyses of bone morphogenetic protein receptor 1A (BMPR‐IA) function during hair follicle development by using a conditional knockout approach. The conditional mutation of Bmpr1a in ventral limb ectoderm and its derivatives (epidermis and hair follicles) resulted in a lack of hair outgrowth from the affected skin regions. Mutant hair follicles exhibited abnormal morphology and lacked hair formation and pigment deposition during anagen. The timing of the hair cycle and the proliferation of hair matrix cells were also affected in the mutant follicles. We demonstrate that signaling via epithelial BMPR‐IA is required for differentiation of both hair shaft and inner root sheath from hair matrix precursor cells in anagen hair follicles but is dispensable for embryonic hair follicle induction. Surprisingly, aberrant de novo hair follicle morphogenesis together with hair matrix cell hyperplasia was observed in the absence of BMPR‐IA signaling within the affected skin of adult mutants. They developed hair follicle tumors from 3 months of age, indicating that inactivation of epidermal BMPR‐IA signaling can lead to hair tumor formation. Taken together, our data provide genetic evidence that BMPR‐IA signaling plays critical and multiple roles in controlling cell fate decisions or maintenance, proliferation, and differentiation during hair morphogenesis and growth, and implicate Bmpr1a as a tumor suppressor in skin tumorigenesis. genesis 39:10–25, 2004. © 2004 Wiley‐Liss, Inc.
Inactivation of the murine Transferrin Receptor 2 gene using the Cre recombinase: LoxP system
Authors: Wallace Daniel F. , Tonks Ian D. , Zournazi Anna , Kay Graham F. , Subramaniam V. Nathan 
Published: April 2004

AbstractSummary: Transferrin Receptor 2 (TfR2) is a key molecule involved in the regulation of iron homeostasis. Mutations in TfR2 lead to type 3 hemochromatosis in humans. We have developed mice with a targeted deletion of TfR2. The Cre‐recombinase:loxP system used to create the mice allows both full deletion and tissue‐specific deletion of TfR2. The development of these mice will provide new models for type 3 hemochromatosis and assist in determining the role of TfR2 in iron metabolism. genesis 39:38–41, 2004. © 2004 Wiley‐Liss, Inc.
The Ser+r83k mutation is a second site mutation of SerD affecting the N‐terminus of serrate
Authors: Trang Tung T. , Tannous Vera , Gu Yi , Mosher Jessica , Fleming Robert J. 
Published: April 2004

AbstractThe Serrate gene encodes an essential ligand for Notch signaling used during development of the adult wing and other systems in Drosophila melanogaster. Animals heterozygous or homozygous for the SerD allele of this gene display characteristic defects in wing margin formation. We have characterized a spontaneously arising intragenic suppressor of SerD named Ser+r83k. Homozygous double mutant Ser+r83k, SerD animals are viable, with normal wing margin formation, but display an aberrant outspread wing posture. The two mutations can be separated by meiotic recombination which restores the SerD mutant phenotype and demonstrates that in the absence of SerD the Ser+r83k mutation is homozygous lethal. These two mutations therefore display allelic compensation. Molecular analysis reveals a single C‐T transition mutation within the 5′ (protein encoding region) of the Ser+r83k transcript. This mutation is predicted to change Arginine176 to Cysteine, possibly leading to altered interactions with the Notch receptor. genesis 39:42–51, 2004. © 2004 Wiley‐Liss, Inc.
A keratin K5Cre transgenic line appropriate for tissue‐specific or generalized cre‐mediated recombination
Authors: Ramirez Angel , Page Angustias , Gandarillas Alberto , Zanet Jennifer , Pibre Sophie , Vidal Miguel , Tusell Laura , Genesca Anna , Whitaker Duncan A. , Melton David W. , Jorcano Jose L. 
Published: April 2004

AbstractWe describe here a mouse line bearing a bovine keratin K5Cre recombinase transgene. These mice showed a dual pattern of Cre‐mediated recombination, depending on the parent transmitting the transgene. In paternal transmission, recombination occurred specifically in the skin and stratified epithelia—as expected according to the expression of endogenous keratin K5. However, constitutive recombination between loxP sites transmitted by the sperm took place when the mother possessed the K5Cre transgene, even when the transgene was absent in the progeny. Cre expression in late‐stage oocytes, with the Cre protein persisting into the developing embryo, leads to the constitutive recombination observed. Thus, this transgenic line allows for both tissue‐specific and generalized recombination, depending on the breeding scheme. genesis 39:52–57, 2004. © 2004 Wiley‐Liss, Inc.
Effects of washing and packing on sensory and chemical parameters in carrots (Daucus carota L)
Authors: Seljåsen Randi , Hoftun Halldor , Selliseth John , Bengtsson Gunnar B 
Published: April 2004

AbstractCarrots washed and packed by hand or machine and stored at 2, 10 or 20 °C in three different package types were analysed for taste, flavour and content of sugars, terpenes, 6‐methoxymellein and ethanol as well as for ethylene, CO2 and O2 concentrations in the packages. Carrots washed by machine had increased micro‐organism decay and higher sensory scores for bitter taste, aftertaste, terpene flavour and odour, green odour and earthy flavour. The ability of packages to ventilate was important to avoid anaerobic conditions that caused decreased sucrose content, increased production of ethanol and a higher intensity of ethanol flavour and sickeningly sweet taste. Increasing temperature enhanced the concentration of ethanol, CO2 and ethylene and decreased the O2 concentration as well as the content of sucrose and total sugar. High temperature also increased the intensity of ethanol flavour and odour, aftertaste, earthy flavour, terpene flavour and bitter taste. Bitter taste was positively correlated with 6‐methoxymellein level, although this level was below the sensory threshold. Bitter taste, earthy flavour and aftertaste were correlated with total terpenes and several individual terpenes. Carrots washed and packed early in the long‐term storage period (November) were more bitter and had a higher level of 6‐methoxymellein and a higher intensity of terpene flavour and odour, green flavour and earthy flavour than those handled in January or March. Copyright © 2004 Society of Chemical Industry