bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid and Sensitive Detection of Retrovirus Entry by Using a Novel Luciferase-Based Content-Mixing Assay
Authors: Kolokoltsov Andrey A. , Davey Robert A.
Published: April 2004

We describe a novel assay that permits measurement of entry of murine leukemia virus and pseudotypes with greater sensitivity and more rapidly than previously possible. To achieve this, we encapsulated a sensitive reporter enzyme, luciferase, directly into fully infectious, intact viral particles. The enzyme is specifically targeted to the viral lumen, as a C-terminal fusion on the viral envelope protein. Only when the incorporated luciferase is released from the viral lumen and gains access to its substrates is light emitted and readily detected. When cells are perfused with luciferin, quantitative measurements of entry can be made in real time on live cells. Uniquely, the amount of cell-bound virus can be determined in the same assay by addition of detergent to expose the luciferase. We demonstrate that virus carrying a mutation in the fusion peptide binds normally to cells but is unable to infect them and gives no entry signal. Using this assay, we show that inhibitors of endosomal acidification inhibit signal from vesicular stomatitis virus pseudotypes but not murine leukemia virus, consistent with a pH-independent mode of entry for the latter virus. Additionally, the fusion kinetics are rapid, with a half-life of 25 min after a delay of 10 to 15 min. The future use of this assay will permit a detailed examination of the entry mechanism of viruses and provide a convenient platform to discover novel entry inhibitors. The design also permits packaging of potential therapeutic protein cargoes into functional virus particles and their specific delivery to cellular targets.
Accumulation of a 3′-Terminal Genome Fragment in Japanese Encephalitis Virus-Infected Mammalian and Mosquito Cells
Authors: Lin Kuo-Chih , Chang Huei-Lan , Chang Ruey-Yi
Published: April 2004

Japanese encephalitis virus (JEV) contains a single positive-strand RNA genome nearly 11 kb in length and is not formally thought to generate subgenomic RNA molecules during replication. Here, we report the abundant accumulation of a 3′-terminal 521- to 523-nucleotide (nt) genome fragment, representing a major portion of the 585-nt 3′ untranslated region, in both mammalian (BHK-21) and mosquito (C6/36) cells infected with any of nine strains of JEV. In BHK-21 cells, the viral genome was detected as early as 24 h postinfection, the small RNA was detected as early as 28 h postinfection, and the small RNA was 0.25 to 1.5 times as abundant as the genome on a molar basis between 28 and 48 h postinfection. In C6/36 cells, the genome and small RNA were present 5 days postinfection and the small RNA was 1.25 to 5.14 times as abundant as the genome. The 3′-terminal 523-nt small RNA contains a 5′-proximal stable hairpin (nt 6 to 56) that may play a role in its formation and the conserved flavivirus 3′-cyclization motif (nt 413 to 420) and the 3′-terminal long stable hairpin structure (nt 440 to 523) that have postulated roles in genome replication. Abundant accumulation of the small RNA during viral replication in both mammalian and mosquito cells suggests that it may play a biological role, perhaps as a regulator of RNA synthesis.
Effect of Extension of the Cytoplasmic Domain of Human Immunodeficiency Type 1 Virus Transmembrane Protein gp41 on Virus Replication
Authors: Chan Woan-Eng , Wang Ya-Lin , Lin Hui-Hua , Chen Steve S.-L.
Published: April 2004

The biological significance of the presence of a long cytoplasmic domain in the envelope (Env) transmembrane protein gp41 of human immunodeficiency virus type 1 (HIV-1) is still not fully understood. Here we examined the effects of cytoplasmic tail elongation on virus replication and characterized the role of the C-terminal cytoplasmic tail in interactions with the Gag protein. Extensions with six and nine His residues but not with fewer than six His residues were found to severely inhibit virus replication through decreased Env electrophoretic mobility and reduced Env incorporation compared to the wild-type virus. These two mutants also exhibited distinct N glycosylation and reduced cell surface expression. An extension of six other residues had no deleterious effect on infectivity, even though some mutants showed reduced Env incorporation into the virus and/or decreased cell surface expression. We further show that these elongated cytoplasmic tails in a format of the glutathione
S
-transferase fusion protein still interacted effectively with the Gag protein. In addition, the immediate C terminus of the cytoplasmic tail was not directly involved in interactions with Gag, but the region containing the last 13 to 43 residues from the C terminus was critical for Env-Gag interactions. Taken together, our results demonstrate that HIV-1 Env can tolerate extension at its C terminus to a certain degree without loss of virus infectivity and Env-Gag interactions. However, extended elongation in the cytoplasmic tail may impair virus infectivity, Env cell surface expression, and Env incorporation into the virus.
The V1/V2 Domain of gp120 Is a Global Regulator of the Sensitivity of Primary Human Immunodeficiency Virus Type 1 Isolates to Neutralization by Antibodies Commonly Induced upon Infection
Authors: Pinter Abraham , Honnen William J. , He Yuxian , Gorny Miroslaw K. , Zolla-Pazner Susan , Kayman Samuel C.
Published: April 2004

A major problem hampering the development of an effective vaccine against human immunodeficiency virus type 1 (HIV-1) is the resistance of many primary viral isolates to antibody-mediated neutralization. To identify factors responsible for this resistance, determinants of the large differences in neutralization sensitivities of HIV-1 pseudotyped with Env proteins derived from two prototypic clade B primary isolates were mapped. SF162 Env pseudotypes were neutralized very potently by a panel of sera from HIV-infected individuals, while JR-FL Env pseudotypes were neutralized by only a small fraction of these sera. This differential sensitivity to neutralization was also observed for a number of monoclonal antibodies (MAbs) directed against sites in the V2, V3, and CD4 binding domains, despite often similar binding affinities of these MAbs towards the two soluble rgp120s. The neutralization phenotypes were switched for chimeric Envs in which the V1/V2 domains of these two sequences were exchanged, indicating that the V1/V2 region regulated the overall neutralization sensitivity of these Envs. These results suggested that the inherent neutralization resistance of JR-FL, and presumably of related primary isolates, is to a great extent mediated by gp120 V1/V2 domain structure rather than by sequence variations at the target sites. Three MAbs (immunoglobulin G-b12, 2G12, and 2F5) previously reported to possess broad neutralizing activity for primary HIV-1 isolates neutralized JR-FL virus at least as well as SF162 virus and were not significantly affected by the V1/V2 domain exchanges. The rare antibodies capable of neutralizing a broad range of primary isolates thus appeared to be targeted to exceptional epitopes that are not sensitive to V1/V2 domain regulation of neutralization sensitivity.
A Mutation in the HLA-B*2705-Restricted NP383-391Epitope Affects the Human Influenza A Virus-Specific Cytotoxic T-Lymphocyte Response In Vitro
Authors: Berkhoff E. G. M. , Boon A. C. M. , Nieuwkoop N. J. , Fouchier R. A. M. , Sintnicolaas K. , Osterhaus A. D. M. E. , Rimmelzwaan G. F.
Published: April 2004

Viruses can exploit a variety of strategies to evade immune surveillance by cytotoxic T lymphocytes (CTL), including the acquisition of mutations in or adjacent to CTL epitopes. Recently, an amino acid substitution (R384G) in an HLA-B*2705-restricted CTL epitope in the influenza A virus nucleoprotein (nucleoprotein containing residues 383 to 391 [NP383-391]; SRYWAIRTR, whereRis the residue that was mutated) was associated with escape from CTL-mediated immunity. The effect of this mutation on the in vitro influenza A virus-specific CTL response was studied. To this end, two influenza A viruses, one with and one without the NP383-391epitope, were constructed by reverse genetics and designated influenza viruses A/NL/94-384R and A/NL/94-384G, respectively. The absence of the HLA-B*2705-restricted CTL epitope in influenza virus A/NL/94-384G was confirmed by using51Cr release assays with a T-cell clone specific for the NP383-391epitope. In addition, peripheral blood mononuclear cells (PBMC) stimulated with influenza virus A/NL/94-384G failed to recognize HLA-B*2705-positive target cells pulsed with the original NP383-391peptide. The proportion of virus-specific CD8+gamma interferon (IFN-γ)-positive T cells in in vitro-stimulated PBMC was determined by intracellular IFN-γ staining after restimulation with virus-infected autologous B-lymphoblastoid cell lines and C1R cell lines expressing only HLA-B*2705. The proportion of virus-specific CD8+T cells was lower in PBMC stimulated in vitro with influenza virus A/NL/94-384G obtained from several HLA-B*2705-positive donors than in PBMC stimulated with influenza virus A/NL/94-384R. This finding indicated that amino acid variations in CTL epitopes can affect the virus-specific CTL response and that the NP383-391epitope is the most important HLA-B*2705-restricted epitope in the nucleoprotein of influenza A viruses.
Copatching and Lipid Raft Association of Different Viral Glycoproteins Expressed on the Surfaces of Pseudorabies Virus-Infected Cells
Authors: Favoreel Herman W. , Mettenleiter Thomas C. , Nauwynck Hans J.
Published: April 2004

Pseudorabies virus (PRV) is a swine alphaherpesvirus that is closely related to human herpes simplex virus (HSV). Both PRV and HSV express a variety of viral envelope glycoproteins in the plasma membranes of infected cells. Here we show that at least four major PRV glycoproteins (gB, gC, gD, and gE) in the plasma membrane of infected swine kidney cells and monocytes seem to be linked, since monospecific antibody-induced patching of any one of these proteins results in copatching of the others. Further, for all four PRV glycoproteins, monospecific antibody-induced patches were enriched in GM1, a typical marker of lipid raft microdomains, but were excluded for transferrin receptor, a nonraft marker, suggesting that these viral proteins may associate with lipid rafts. However, only gB and, to a lesser extent, gE were found in lipid raft fractions by using detergent floatation assays, indicating that gC and gD do not show strong lipid raft association. Addition of methyl-β-cyclodextrin (MCD), a cholesterol-depleting agent that is commonly used to disrupt lipid rafts, only slightly reduced copatching efficiency between the different viral proteins, indicating that other factors, perhaps tegument-glycoprotein interactions, may be important for the observed copatching events. On the other hand, MCD strongly reduced polarization of the antibody-induced viral glycoprotein patches to a cap structure, a gE-dependent process that has been described for specific PRV- and HSV-infected cells. Therefore, we hypothesize that efficient gE-mediated capping of antibody-antigen patches may require the lipid raft-associated signal transduction machinery.
The Papillomavirus E7 Oncoprotein Is Ubiquitinated by UbcH7 and Cullin 1- and Skp2-Containing E3 Ligase
Authors: Oh Kwang-Jin , Kalinina Anna , Wang Jing , Nakayama Keiko , Nakayama Keiichi I. , Bagchi Srilata
Published: April 2004

Recurrent infections with high-risk human papillomaviruses (HPVs) are associated with human cervical cancers. All HPV-associated cancer tissues express the viral oncoproteins E6 and E7, which stimulate cell growth. The expression of E7 is crucial for both the initiation and the maintenance of HPV-associated cancer. Recent studies showed that the level of E7 in cancer cells is regulated by ubiquitin-dependent proteolysis through the 26S proteasome. In this study, we characterized the enzymes involved in the ubiquitin-dependent proteolysis of E7. We show that UbcH7, an E2 ubiquitin-conjugating enzyme, is specifically involved in the ubiquitination of E7. Furthermore, we show that E7 interacts with the SCF (Skp-Cullin-F box) ubiquitin ligase complex containing Cullin 1 (Cul1) and Skp2 and can be ubiquitinated by the Cul1-containing ubiquitin ligase in vitro. Coimmunoprecipitation analyses revealed that E7 interacts with Skp2 and Cul1 in vivo. Finally, the half-life of E7 was found to be significantly longer in Skp2
−/−
mouse embryo fibroblasts (MEFs) than in wild-type MEFs. Taken together, these results suggest that the Cul1- and Skp2-containing ubiquitin ligase plays a role in the ubiquitination and proteolysis of E7. In HPV type 16-containing cervical carcinoma cell line Caski, E7 localizes to both the cytoplasm and the nucleus. Brief treatment of Caski cells with MG132 (a proteasome inhibitor) causes the accumulation of E7 in discrete nuclear bodies. These nuclear bodies are detergent insoluble and contain polyubiquitinated E7. We suggest that E7 relocates to specific nuclear bodies for proteolysis in HPV-containing epithelial cells.
Rice Dwarf Phytoreovirus Segment S6-Encoded Nonstructural Protein Has a Cell-to-Cell Movement Function
Authors: Li Yi , Bao Yi M. , Wei Chun H. , Kang Zhen S. , Zhong Yong W. , Mao Peng , Wu Gang , Chen Zhang L. , Schiemann Joachim , Nelson Richard S.
Published: April 2004

Rice dwarf virus(RDV) is a member of the genusPhytoreovirus, which is composed of viruses with segmented double-stranded RNA genomes. Proteins that support the intercellular movement of these viruses in the host have not been identified. Microprojectile bombardment was used to determine which open reading frames (ORFs) support intercellular movement of a heterologous virus. A plasmid containing an infectious clone ofPotato virus X(PVX) defective in cell-to-cell movement and expressing either β-glucuronidase or green fluorescent protein (GFP) was used for cobombardment with plasmids containing ORFs from RDV gene segments S1 through S12 onto leaves ofNicotiana benthamiana. Cell-to-cell movement of the movement-defective PVX was restored by cobombardment with a plasmid containing S6. In the absence of S6, no other gene segment supported movement. Identical results were obtained withNicotiana tabacum, a host that allows fewer viruses to infect and spread within its tissue. S6 supported the cell-to-cell movement of the movement-defective PVX in sink and source leaves ofN. benthamiana. A mutant S6 lacking the translation start codon did not complement the cell-to-cell movement of the movement-defective PVX. An S6 protein product (Pns6)-enhanced GFP fusion was observed near or within cell walls of epidermal cells fromN. tabacum. By immunocytochemistry, unfused Pns6 was localized to plasmodesmata in rice leaves infected with RDV. S6 thus encodes a protein with characteristics identical to those of other viral proteins required for the cell-to-cell movement of their genome and therefore is likely required for the cell-to-cell movement of RDV.
Characterization of a Subtype D Human Immunodeficiency Virus Type 1 Isolate That Was Obtained from an Untreated Individual and That Is Highly Resistant to Nonnucleoside Reverse Transcriptase Inhibitors
Authors: Gao Yong , Paxinos Ellen , Galovich Justin , Troyer Ryan , Baird Heather , Abreha Measho , Kityo Cissy , Mugyenyi Peter , Petropoulos Christos , Arts Eric J.
Published: April 2004

Human immunodeficiency virus type 1 (HIV-1) isolates derived from HIV-infected, treatment-naive Ugandan infants were propagated and tested for sensitivity to antiretroviral (ARV) drugs. Although most subtype A and D isolates displayed inhibition profiles similar to those of subtype B strains, a subtype D isolate identified as D14-UG displayed high-level resistance to nevirapine in peripheral blood mononuclear cell cultures (>2,000-fold) and in MT4 cell cultures (∼800-fold) but weaker resistance to delavirdine (∼13-fold) and efavirenz (∼8-fold) in MT4 cell cultures. To investigate the possible mechanism for this resistance to nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs), the RT coding region in
pol
was sequenced and compared to the consensus RT sequence of NNRTI-resistant and NNRTI-sensitive subtype A, B, and D HIV-1 isolates. D14-UG did not contain the classic amino acid substitutions conferring NNRTI resistance (e.g., Y181C, K103N, and G190A) but did have some putative sites associated with drug resistance, I135L, T139V, and V245T. Wild-type and mutated protease-RT genes from D14-UG and an NNRTI-sensitive subtype D isolate from Uganda (D13-UG) were cloned into pNL4-3 to produce recombinant viruses and to determine the effects of the mutations on susceptibility to ARV drugs, specifically, NNRTIs. The results showed that I135L and/or V245T mutations can confer high-level resistance to nevirapine and delavirdine as well as low level cross-resistance to efavirenz. Finally, ex vivo fitness analyses suggested that NNRTI-resistant sites 135L and 245T in wild-type isolate D14-UG may reduce RT fitness but do not have an impact on the fitness of the primary HIV-1 isolate.
Binding and Susceptibility to Postentry Restriction Factors in Monkey Cells Are Specified by Distinct Regions of the Human Immunodeficiency Virus Type 1 Capsid
Authors: Owens Christopher M. , Song Byeongwoon , Perron Michel J. , Yang Peter C. , Stremlau Matthew , Sodroski Joseph
Published: April 2004

In
cells of Old World and some New World monkeys, dominant factors
restrict human immunodeficiency virus type 1 (HIV-1)
infections after virus entry. The simian immunodeficiency virus
SIV
mac
is less susceptible to these restrictions, a property
that is determined largely by the viral capsid protein. For this study,
we altered exposed amino acid residues on the surface of the HIV-1
capsid, changing them to the corresponding residues found on the
SIV
mac
capsid. We identified two distinct pathways of escape
from early, postentry restriction in monkey cells. One set of mutants
that were altered near the base of the cyclophilin A-binding loop of
the N-terminal capsid domain or in the interdomain linker exhibited a
decreased ability to bind the restricting factor(s). Consistent with
the location of this putative factor-binding site, cyclophilin A and
the restricting factor(s) cooperated to achieve the postentry block. A
second set of mutants that were altered in the ridge formed by helices
3 and 6 of the N-terminal capsid domain efficiently bound the
restricting factor(s) but were resistant to the consequences of factor
binding. These results imply that binding of the simian restricting
factor(s) is not sufficient to mediate the postentry block to HIV-1 and
that SIV
mac
capsids escape the block by decreases in both
factor binding and susceptibility to the effects of the
factor(s).
Impact of Mutations in the Coreceptor Binding Site on Human Immunodeficiency Virus Type 1 Fusion, Infection, and Entry Inhibitor Sensitivity
Authors: Reeves Jacqueline D. , Miamidian John L. , Biscone Mark J. , Lee Fang-Hua , Ahmad Navid , Pierson Theodore C. , Doms Robert W.
Published: April 2004

An increasingly large number of antiviral agents that prevent entry of human immunodeficiency virus (HIV) into cells are in preclinical and clinical development. The envelope (Env) protein of HIV is the major viral determinant that affects sensitivity to these compounds. To understand how changes in Env can impact entry inhibitor sensitivity, we introduced six mutations into the conserved coreceptor binding site of the R5 HIV-1 strain YU-2 and measured the effect of these changes on CD4 and coreceptor binding, membrane fusion levels and rates, virus infection, and sensitivity to the fusion inhibitors enfuvirtide (T-20) and T-1249, the CCR5 inhibitor TAK-779, and an antibody to CD4. The mutations had little effect on CD4 binding but reduced CCR5 binding to various extents. In general, reductions in coreceptor binding efficiency resulted in slower fusion kinetics and increased sensitivity to TAK-779 and enfuvirtide. In addition, low CCR5 binding usually reduced overall fusion and infection levels. However, one mutation adjacent to the bridging sheet β21 strand, P438A, had little effect on fusion activity, fusion rate, infectivity, or sensitivity to enfuvirtide or T-1249 despite causing a marked reduction in CCR5 binding and a significant increase in TAK-779 sensitivity. Thus, our findings indicate that changes in the coreceptor binding site of Env can modulate its fusion activity, infectivity, and entry inhibitor sensitivity by multiple mechanisms and suggest that reductions in coreceptor binding do not always result in prolonged fusion kinetics and increased sensitivity to enfuvirtide.
The Human-Animal Bond and Self Psychology: Toward a New Understanding
Authors: Brown Sue-Ellen
Published: April 2004

The purpose of this paper is to introduce and define self psychology and its concepts (self and selfobject) so that they can be applied toward a new understanding of the human-nonhuman animal bond. The paper utilizes selected literature from both self psychology and the human-animal bond fields. The paper contains four primary conclusions: 1. Self psychology provides a unique model for understanding the depth and meaning of human-animal relationships; 2. Companion animals and humans can be equally important in their selfobject roles; 3. Self psychology can offer a model for understanding individual differences in attachment to companion animals; and 4. A future direction includes finding ways to assess self psychology constructs in order to measure the depth and function of the selfobject relationship.
Presenting a model of change
Authors: Lamie Judith M.
Published: April 2004

The literature surrounding the process of curriculum innovation and change abounds with the assumption that change is a difficult, often painful and hugely complex process. It involves educational, political, national, institutional and personal issues. It challenges the very fabric of our society, and our roles not only as professionals, but as people. This article introduces a model of change developed during a research study of Japanese teachers of English taking part in an overseas teacher-training programme designed to support a major curriculum innovation. The research investigated the influence of the programme, and examined a group of teachers, analysing their changes in attitude, perceived methodology and practice before and after the in-service period. The findings demonstrated that in all cases changes towards the aims of the innovation had taken place. In the wider context, an analysis of the process of change indicated that there may be a number of interconnected areas that affect individual actions. This resulted in the development of a model of change. The paper will set this new model into its theoretical context by referring to established models and highlight a number of critical features that were shown to have an impact on the process of change.
Collaborative dialogue with student teachers as a follow-up to teacher in-service education and training
Authors: Atay Derin
Published: April 2004

This study evaluates the success of collaborative dialogue between students and co-operating teachers as a follow-up to in-service education and teaching (INSET). Current INSET programmes are on the whole found to be insufficient due to the fact that they do not provide the participant teachers with opportunities to reflect on their own experiences, nor do they given them support in modifying teaching practice. The qualitative and quantitative results of this study show that taking part in a collaborative dialogue with student teachers following INSET impacts positively on the professional development of participating teachers. This may help to resolve the problems and difficulties associated with INSET programmes in general.
Teaching Critical Thinking by Examining Assumptions
Authors: Yanchar Stephen C. , Slife Brent D.
Published: April 2004

We describe how instructors can integrate the critical thinking skill of examining theoretical assumptions (e.g., determinism and materialism) and implications into psychology courses. In this instructional approach, students formulate questions that help them identify assumptions and implications, use those questions to identify and examine the assumptions and implications of theories being studied, and develop defensible positions on the tenability of various theoretical assumptions. We suggest that this instructional approach fits within extant critical thinking proposals, such as those formulated by King (1995) and Halonen (1995).
Converting an Experimental Laboratory Course from Paper and Pencil to Computer
Authors: Hamilton Maryellen , Geraci Lisa
Published: April 2004

This article provides suggestions for developing a laboratory-based research methods course using computers. We describe important considerations for creating this type of course including selecting software, choosing experiments, and teaching students with different levels of computer skill. We also include 3 model projects that required increasing methodological and programming knowledge. The ultimate goal of the course was to have students submit a final project that they designed, ran, and programmed independently.
Learning the Rescorla–Wagner Model of Pavlovian Conditioning: An Interactive Simulation
Authors: Renner Michael J.
Published: April 2004

The Rescorla–Wagner model is one of the cornerstones of learning theory. However, many students in undergraduate courses find the model's concepts difficult to grasp, and the model is often the students' first exposure to computational models in psychology. This article describes an interactive simulation based on an Excel® spreadsheet program that implements the model over 500 trials using parameters specified by the student. Students report favorable reactions to the classroom use of the simulation.
Preparation and Properties of a Structually Novel Heterocyclic Dispiro Compound, 3,10-Dimethyl-3,10-diazadispiro[5.0.5.4]hexadeca-1,4,8,11-tetraene
Authors: Muramatsu Takashi , Toyota Azumao , Adachi Nao
Published: April 2004

The two-electron reduction of 3 with sodium amalgam in degassed acetonitrile affords 4 in quantitative yield. Under deoxygenerated conditions, 4 is stable for a long time at room temperature, but slowly undergoes an opening of the cyclohexane ring skeleton with elimination of methyl groups to yield 5 at about 200 °C. At the same time, a small amount of 6 is obtained by fission of a CC single bond of the cyclohexane ring skeleton with the transfer of hydrogen atom.
Neural Correlates of Cat Odor-Induced Anxiety in Rats: Region-Specific Effects of the Benzodiazepine Midazolam
Authors: McGregor Iain S. , Hargreaves Garth A. , Apfelbach Raimund , Hunt Glenn E.
Published: April 2004

Cat odor elicits a profound defensive reaction in rats that is reduced by benzodiazepine drugs. The neural correlates of this phenomenon were investigated here using Fos immunohistochemistry. Rats received either midazolam (0.75 mg/kg, s.c.) or vehicle and were exposed to pieces of a collar that had been worn by a domestic cat or an unworn (dummy) collar. Cat odor caused midazolam-sensitive defensive behavioral responses, including avoidance of collar contact, inhibition of grooming, and prolonged rearing. Cat odor exposure induced Fos expression in the posterior accessory olfactory bulb (glomerular, mitral, and granule cell layers), with granule cell layer activation attenuated by midazolam. High basal Fos expression, and some cat odor-associated Fos expression, was evident in the main olfactory bulb (glomerular cell layer), and midazolam exerted a strong inhibitory effect in this region. Midazolam inhibited Fos expression in key limbic regions involved in pheromone transduction (medial amygdala and bed nucleus of the stria terminalis) and defensive behavior (prelimbic cortex, lateral septum, lateral and medial preoptic areas, and dorsal premammillary nucleus). However, midazolam failed to affect cat odor-related Fos expression in a range of key defense-related sites, including the ventromedial hypothalamic nucleus, paraventricular nucleus of the hypothalamus, periaqueductal gray, and cuneiform nucleus. These results indicate that midazolam exerts a region-specific effect on the neural substrates activated by predator odor, with effects in the lateral septum and dorsal premammillary nucleus likely to be of major importance. These findings also suggest the intriguing hypothesis that cat odor is processed by rats as a “pheromone-like” stimulus.
Involvement of Monkey Inferior Colliculus in Spatial Hearing
Authors: Zwiers Marcel P. , Versnel Huib , Van Opstal A. John
Published: April 2004

The midbrain inferior colliculus (IC) is implicated in coding sound location, but evidence from behaving primates is scarce. Here we report single-unit responses to broadband sounds that were systematically varied within the two-dimensional (2D) frontal hemifield, as well as in sound level, while monkeys fixated a central visual target.

Results show that IC neurons are broadly tuned to both sound-source azimuth and level in a way that can be approximated by multiplicative, planar modulation of the firing rate of the cell. In addition, a fraction of neurons also responded to elevation. This tuning, however, was more varied: some neurons were sensitive to a specific elevation; others responded to elevation in a monotonic way. Multiple-linear regression parameters varied from cell to cell, but the only topography encountered was a dorsoventral tonotopy.

In a second experiment, we presented sounds from straight ahead while monkeys fixated visual targets at different positions. We found that auditory responses in a fraction of IC cells were weakly, but systematically, modulated by 2D eye position. This modulation was absent in the spontaneous firing rates, again suggesting a multiplicative interaction of acoustic and eye-position inputs. Tuning parameters to sound frequency, location, intensity, and eye position were uncorrelated. On the basis of simulations with a simple neural network model, we suggest that the population of IC cells could encode the head-centered 2D sound location and enable a direct transformation of this signal into the eye-centered topographic motor map of the superior colliculus. Both signals are required to generate rapid eye-head orienting movements toward sounds.
geminiEncodes a Zebrafish L-Type Calcium Channel That Localizes at Sensory Hair Cell Ribbon Synapses
Authors: Sidi Samuel , Busch-Nentwich Elisabeth , Friedrich Rainer , Schoenberger Ulrike , Nicolson Teresa
Published: April 2004

L-type Ca2+channels (LTCCs) drive the bulk of voltage-gated Ca2+entry in vertebrate inner ear hair cells (HCs) and are essential for mammalian auditory processing. LTCC currents have been implicated in neurotransmitter release at the HC afferent active zone, the ribbon synapse. It is likely that LTCCs play a direct role in vesicle fusion; however, the subcellular localization of the channels in HCs has not been fully resolved. Via positional cloning, we show that mutations in a zebrafish LTCC encoding gene,cav1.3a, underlie the auditory-vestibular defects ofgemini(gem) circler mutants.gemhomozygous receptor mutant HCs display normal cell viability, afferent synaptogenesis, and peripheral innervation, yet exhibit strongly reduced extracellular potentials (∼50% of wild-type potentials). Apical FM1-43 uptake, however, is unaffected ingemmutant HCs, suggesting that mechanotransduction channels are functional. Using a Gem-specific antibody, we show that the bulk of Gem/Cav1.3a immunoreactivity in HCs is restricted to basally located focal spots. The number and location of focal spots relative to nerve terminals, and their remarkable ring-shaped structure, which is reminiscent of synaptic dense bodies, are consistent with Gem/Cav1.3a channels clustering at HC ribbon synapses.
Peripheral Treatment with Enoxaparin, a Low Molecular Weight Heparin, Reduces Plaques and β-Amyloid Accumulation in a Mouse Model of Alzheimer's Disease
Authors: Bergamaschini Luigi , Rossi Emanuela , Storini Claudio , Pizzimenti Simone , Distaso Maria , Perego Carlo , De Luigi Ada , Vergani Carlo , Grazia De Simoni Maria
Published: April 2004

We investigated the effect of long-term, peripheral treatment with enoxaparin, a low molecular weight heparin, in transgenic mice overexpressing human amyloid precursor protein751. Enoxaparin (6 IU per mouse intraperitoneally, three times a week for 6 months) significantly lowered the number and the area occupied by cortical β-amyloid deposits and the total β-amyloid (1-40) cortical concentration. Immunocytochemical analysis of glial fibrillary acid protein-positive cells showed that enoxaparin markedly reduced the number of activated astrocytes surrounding β-amyloid deposits.In vitro, the drug dose-dependently attenuated the toxic effect of β-amyloid on neuronal cells. Enoxaparin dose-dependently reduced the ability of β-amyloid to activate complement and contact systems, two powerful effectors of inflammatory response in AD brain. By reducing the β-amyloid load and cytotoxicity and proinflammatory activity, enoxaparin offers promise as a tool for slowing the progression of Alzheimer's disease.
Activity-Dependent Phosphorylation of Tyrosine Hydroxylase in Dopaminergic Neurons of the Rat Retina
Authors: Witkovsky Paul , Veisenberger Eleonora , Haycock John W. , Akopian Abram , Garcia-Espana Antonio , Meller Emanuel
Published: April 2004

We studiedin vivoactivity-dependent phosphorylation of tyrosine hydroxylase (TH) in dopaminergic (DA) neurons of the rat retina. TH phosphorylation (TH-P) was evaluated by immunocytochemistry, using antibodies specific for each of three regulated phosphorylation sites. TH synthesis rate was measured by dihydroxyphenylalanine (DOPA) accumulation in the presence of NSD-1015, an inhibitor of aromatic amino acid decarboxylase. TH-P was increased markedly by light or after intraocular injection of GABAAand glycine inhibitors. All three phosphospecific antibodies responded similarly to test drugs or light. A 30 min exposure to light increased DOPA accumulation by threefold over that seen after 30 min in darkness. Immunostaining to an anti-panNa channel antibody was found in all parts of the DA neuron. TTX blocked TH-P induced by light or GABA/glycine inhibitors but only in varicosities of the DA axon plexus, not in perikarya or dendrites. Veratridine increased TH-P in all parts of the DA neuron. The distribution of the monoamine vesicular transporter 2 was shown by immunocytochemistry to reside in varicosities of the DA plexus but not in dendrites, indicating that the varicosities are sites of dopamine release. Collectively, these data indicate that, in the retina, dopamine synthesis in varicosities is affected by the spiking activity of retinal neurons, possibly including that of the DA neurons themselves.
Sol–Gel Template Synthesis of Aluminum Oxide Microtubules
Authors: Peng T. , Yang H. , Dai K. , Nakanishi K. , Hirao K.
Published: April 2004

Al2O3 microtubules with ca. 60–600 μm in lengths and 2–16 μm in outer diameter have been prepared using water‐soluble ammonium tartrate crystal as a template in a sol‐gel method using aluminum sec‐butoxide (ASB) as starting materials, which may have potential application in catalytic materials, electronic science or separation technology.
Enhanced Strength and Ductility in Ultrafine‐Grained Aluminium Produced by Accumulative Roll Bonding
Authors: Höppel H.W. , May J. , Göken M.
Published: April 2004

Bulk ultrafine‐grained (UFG) materials, produced by severe plastic deformation (SPD) have recently received considerable scientific attention. In this work the authors explore, whether the so‐called “paradox of ductility and strength” is also true for UFG Aluminium produced by an Accumulative Roll Bonding (ARB) process and to clarify the effect of the SPD‐related pre‐deformation on the stress‐strain behaviour.
Heat transfer in poly(methyl acrylate) by photoacoustic measurements
Authors: Jothi Rajan M. A. , Vivekanandam T. S. , Ramakrishnan S. K. , Ramachandran K. , Umapathy S.
Published: April 2004

The thermal properties (thermal diffusivity, thermal effusivity, thermal conductivity, and specific heat capacity) of poly(methyl acrylate), which was obtained by ultrasonochemical polymerization, were measured experimentally with photoacoustic and other techniques. In addition, the thermal expansion of poly(methyl acrylate) was measured experimentally with an indigenously modified Fizeau's apparatus and is reported here for the first time to an accuracy of 0.05%. The results were compared with the available literature values and examined. Sinclare's apparatus was used to determine the specific heat capacity and matched well with differential scanning calorimetry measurements. The method‐of‐mixtures technique was an alternative method of determining the specific heat capacity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1071–1076, 2004
A new approach for selective surface modification of fluoropolymers by remote plasmas
Authors: Park Y. W. , Inagaki N.
Published: April 2004

Ethylene‐co‐tetrafluoroethylene (ETFE) and poly (vinylidene fluoride) (PVDF) films were exposed to the remote Ar, H2, and O2 plasmas. The modified polymer surfaces were characterized by X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurement. The plasma exposure led to weight loss and changes in the chemical composition on the polymer surface. Selective surface modification of fluoropolymers introduces various functional groups without altering the bulk properties. The results may be summarized as follows: the remote hydrogen plasma was the most effective in alternation from CF to CH (abstraction of fluorine). On the other hand, the remote oxygen plasma was unfavorable to abstract fluorine atoms, but effective in dehydrogenation (abstraction of hydrogen). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1012–1020, 2004
Rheological properties, oil, and thermal resistance in sulfur‐cured CPE/NR blends
Authors: Sirisinha Chakrit , Saeoui Pongdhorn , Pattanawanidchai Sirichai
Published: April 2004

The use of natural rubber (NR) for partly substituting elastomeric chlorinated polyethylene (CPE) was carried out. Sulfur curing was used to vulcanize NR phase in the blends. Mechanical, rheological, and thermal aging properties as well as oil resistance of the blends were investigated. The amount of NR in blends significantly affects properties of the blends. With NR content in blends up to 20 wt %, tensile properties are similar to those of the pure CPE, even after either oil immersion or thermal aging. Rheological properties of CPE/NR blends determined from the rubber process analyzer (RPA 2000) and parallel‐plate rheometer are controlled strongly by the blend composition. The viscoelastic behavior of pure CPE and the blends with CPE as a major component is governed by the viscous response, which could be seen from the high damping factor, particularly at high strain, the short linear viscoelastic range, and the high degree of pseudoplasticity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1129–1135, 2004
Thermal properties of poly(vinyl alcohol)–solute blends studied by TMDSC
Authors: Stavropoulou A. , Papadokostaki K. G. , Sanopoulou M.
Published: April 2004

A thermal analysis study of blends of semicrystalline poly(vinyl alcohol) (PVA) with a pharmaceutical substance, buflomedil pyridoxal phosphate (BPP) is presented. Temperature‐modulated DSC (TMDSC) was used to determine the Tg as well as the crystallinity of blends with various polymer to drug ratios, for different annealing procedures. Positive deviations from a simple expression for the composition dependence of the glass transition of the blend were found. This result, together with the increased thermal stability of PVA–BPP blends, evidenced by TGA analysis, indicates the existence of specific interactions between the polar groups of the two components. The incorporation of dispersed BPP in the PVA matrix results in a composition‐dependent lowering of the polymer's Tm and degree of crystallinity. In addition, we found that, while melting of pure PVA is predominantly reversing, its melting in the blends acquires an increasingly higher nonreversing component with increasing BPP content in the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1151–1156, 2004
Swelling behavior of polyelectrolyte complex hydrogels composed of chitosan and hyaluronic acid
Authors: Kim Seon Jeong , Lee Ki Jung , Kim Sun I.
Published: April 2004

Polyelectrolyte complex (PEC) hydrogels composed of various weight ratios of chitosan and hyaluronic acid were prepared. The PEC hydrogels were formed by the reaction of the oppositely charged chitosan polymers. The PEC films swelled in water rapidly, reaching equilibrium within 30 min, and exhibited relatively high swelling ratios, 243–322%, at 25°C. The swelling ratio increased with increasing temperature. The transport phenomena of all PEC samples were non‐Fickian and diffusion and relaxation controlled. The diffusion coefficients of the PEC films ranged from 2.22 × 10−6 to 10.05 × 10−6 cm2/s. The activation energy of the polyelectrolyte complexes ranged from 37.14 to 54.58 kJ/mol and proved to be hydrophilic. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1097–1101, 2004
Comparison of different foaming agents in making plywood glue
Authors: Luukko Petra , Nyström Marianne , Rainio Jouni
Published: April 2004

Foaming of a phenol formaldehyde resin was studied. Twenty‐one foaming agents were tried out in the experiments. Foaming was evaluated by viscosity, density, and surface tension measurements. The study shows that spray dried blood and β‐lactoglobulin‐enriched whey were the best foaming agents to foam phenol formaldehyde resin. There are also some other materials, which might work as foaming agents for phenol formaldehyde resin after some formula optimization. They include sodium lauryl sulfate, sodium‐n‐alkyl (C10‐C13) benzene sulfonate, and a fatty acid amine derivate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1060–1064, 2004
Synthesis of 2′‐Aminoalkyl‐Substituted Fluorinated Nucleobases and Their Influence on the Kinetic Properties of Hammerhead Ribozymes
Authors: Klöpffer Astrid E. , Engels Joachim W.
Published: April 2004

Hammerhead ribozymes are ribonucleic acids that catalyse the hydrolytic cleavage of RNA. They interfere with gene expression in a highly specific manner and recognize the mRNA target through Watson–Crick base pairing. To overcome the problem of point mutations (Watson–Crick “mismatches”) occurring in viral genomes, we developed 2′‐aminoethyl‐substituted fluorinated nucleosides, which are universal nucleobases. The highly efficient synthetic pathway, which features a direct phthaloylamination of a primary alcohol under Mitsunobu conditions, leads to modified phosphoroamidites. The 1′‐deoxy‐1′‐(4,6‐difluoro‐1H‐benzimidazol‐1‐yl)‐2′‐(β‐aminoethyl)‐β‐D‐ribofuranose nucleoside analogue does not differentiate between the four natural nucleosides and leads to a RNA duplex that is as stable as the unmodified parent duplex. Upon incorporation into a ribozyme, the analogue's catalytic activity is equal for all four possible substrates, and the cleavage rates for the modified ribozymes are significantly higher (up to a factor of 13) than for the natural Watson–Crick “mismatch” base pairs. In agreement with the thermodynamic data obtained by measurement of the Tm values of the RNA 12‐mers, the cleavage rates for the 2′‐substituted fluorinated benzimidazole derivative 4 are slightly higher than for the corresponding fluorinated benzene derivative 3.
Synthesis of Phthalide Derivatives Using Nickel‐Catalyzed Cyclization of o‐Haloesters with Aldehydes
Authors: Rayabarapu Dinesh Kumar , Chang Hong‐Tai , Cheng Chien‐Hong
Published: April 2004

The reaction of o‐bromobenzoate (1 b) with benzaldehyde (2 a) in the presence of [NiBr2(dppe)] (dppe=1,2‐bis(diphenylphosphino)ethane) and zinc powder in THF (24 hours, reflux temperature), afforded 3‐phenyl‐3H‐isobenzofuran‐1‐one (3 a) in an 86 % yield. Similarly, o‐iodobenzoate reacts with 2 a to give 3 a, but in a lower yield (50 %). A series of substituted aromatic and aliphatic aldehydes (2 b, 4‐MeC6H4CHO; 2 c, 4‐MeOC6H4CHO; 2 d, 3‐MeOC6H4CHO; 2 e, 2‐MeOC6H4CHO; 2 f, 4‐CNC6H4CHO; 2 g, 4‐(Me)3CC6H4CHO; 2 h, 4‐C6H5C6H4CHO; 2 i, 4‐ClC6H4CHO; 2 j, 4‐CF3C6H4CHO; 2 k, CH3(CH2)5CHO; 2 l, CH3(CH2)2CHO) also underwent cyclization with o‐bromobenzoate (1 b) producing the corresponding phthalide derivatives in moderate to excellent yields and with high chemoselectivity. Like 1 b, methyl 2‐bromo‐4,5‐dimethoxybenzoate (1 c) reacts with tolualdehyde (2 b) to give the corresponding substituted phthalide 3 m in a 71 % yield. The methodology can be further applied to the synthesis of six‐membered lactones. The reaction of methyl 2‐(2‐bromophenyl)acetate (1 d) with benzaldehyde under similar reaction conditions afforded six‐membered lactone 3 o in a 68 % yield. A possible catalytic mechanism for this cyclization is also proposed.
Intermetallics as Zintl Phases: Yb2Ga4Ge6 and RE3Ga4Ge6 (RE=Yb, Eu): Structural Response of a [Ga4Ge6]4− Framework to Reduction by Two Electrons
Authors: Zhuravleva Marina A. , Salvador James , Bilc Daniel , Mahanti Subhendra D. , Ireland John , Kannewurf Carl R. , Kanatzidis Mercouri G.
Published: April 2004

Two new intermetallic compounds, Yb2Ga4Ge6 and Yb3Ga4Ge6, were obtained from reactions in molten Ga. A third compound, Eu3Ga4Ge6, was produced by direct combination of the elements. The crystal structures of these compounds were studied by single‐crystal X‐ray diffraction. Yb2Ga4Ge6 crystallizes in an orthorhombic cell with a=4.1698(7), b=23.254(4), c=10.7299(18) Å in the polar space group Cmc21. The structure of RE3Ga4Ge6 is monoclinic, space group C2/m, with cell parameters a=23.941(6), b=4.1928(11), c=10.918(3) Å, β=91.426(4)° for RE=Yb, and a=24.136(2), b=4.3118(4), c=11.017(1) Å, β=91.683(2)° for RE=Eu. The refinement [I>2 σ(I)] converged to the final residuals R1/wR2=0.0229/0.0589, 0.0411/0.1114, and 0.0342/0.0786 for Yb2Ga4Ge6, Yb3Ga4Ge6, and Eu3Ga4Ge6, respectively. The structures of these two families of compounds can be described by a Zintl concept of bonding, in which the three‐dimensional [Ga4Ge6]n− framework serves as a host and electron sink for the electropositive RE atoms. The structural relation of RE3Ga4Ge6 to of Yb2Ga4Ge6 lies in a monoclinic distortion of the orthorhombic cell of Yb2Ga4Ge6 and reduction of the [Ga4Ge6] network by two electrons per formula unit. The results of theoretical calculations of the electronic structure, electrical transport data, and thermochemical and magnetic measurements are also reported.
Photochemische Erzeugung und [4 + 2]‐Cycloaddition von Singulett‐Sauerstoff im Mikrofallfilmreaktor
Authors: Jähnisch K.
Published: April 2004

No abstracts.
Optimizing the point spread function in phase‐encoded magnetic resonance microscopy
Authors: Webb A.G.
Published: April 2004

Three‐dimensional phase‐encoded magnetic resonance microscopy is the most promising method for obtaining images with isotropic spatial resolutions on the order of a few micrometers. The attainable spatial resolution is limited by the available gradient strength (Gmax) and the molecular self‐diffusion coefficient (D) of the sample. In this study, numerical simulations in the microscopic‐size regime are presented in order to show that for given values of Gmax and D, there exists an optimum number of phase‐encoding steps that maximize the spatial resolution in terms of minimizing the full‐width at half‐maximum (FWHM) of the image point spread function (PSF). Unlike the case of “macroscopic” imaging, in which diffusion plays an insignificant role in determining spatial resolution, acquiring data beyond this optimal value actually degrades the image PSF. An alternative version of phase encoding, using a variable phase‐encoding time rather than a variable gradient strength, is analyzed in terms of improvements in the image PSF and/or reductions in the data acquisition time for a given spatial resolution. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 22A: 25–36, 2004.