bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental analysis and subcellular localization of the murine homologue of
ELL
Authors: Thirman Michael J. , Diskin Emily B. , Bin Steven S. , Ip Hon S. , Miller Jacqueline M. , Simon M. Celeste
Published: July 2002

The
ELL
gene was first identified by its involvement with
MLL
in the translocation (11;19)(q23;p13.1) in acute myeloid leukemia. To date, nine other
MLL
partner genes have been cloned, but their precise functions have yet to be determined. To characterize the functions of
ELL
further, we have cloned the murine homologue of
ELL
and have found that the gene is highly conserved at the nucleotide and amino acid level. The open reading frame of the murine homologue contains 602 aa, slightly smaller than the 621 aa in the human gene. With Northern blot analysis, a 3.4-kb transcript is detected in all tissues examined with greatest levels of expression in the liver. Unlike human
ELL
, only a single transcript can be detected with either murine coding sequence or 3′ untranslated region probes. To examine the spatial and temporal pattern of expression in murine development,
in situ
hybridization studies were performed with sense and antisense riboprobes from the 3′ untranslated region of murine
Ell
.
Ell
is expressed diffusely by embryonic day 7.5 (E7.5). In addition, high levels of expression can be detected in maternally derived decidual tissue. At E14.5,
Ell
is expressed diffusely throughout the embryo. However by E16.5, specific expression in the liver and gastrointestinal tract becomes prominent and remains so in both neonates and adults. To determine the subcellular localization of ELL, we developed a polyclonal antiserum to ELL that was used for immunofluorescence studies in COS-7, HeLa, NIH 3T3, and A7r5 cells. The ELL protein was localized to the nucleus but excluded from nucleoli in all cell lines examined. Recently, the gene product of
ELL
was found to function as an RNA polymerase II elongation factor, an activity that is consistent with our immunofluorescence data. Thus, these studies extend our understanding of the normal functions of
ELL
and provide additional insight into its aberrant function when fused to
MLL
in acute myeloid leukemia.
Reversible dissociation of coatomer: Functional characterization of a β/δ-coat protein subcomplex
Authors: Pavel Jochen , Harter Cordula , Wieland Felix T.
Published: July 2002

COPI-coated vesicles mediate protein transport within the early secretory pathway. Their coat consists of ADP ribosylation factor (ARF1, a small guanosine nucleotide binding protein), and coatomer, a cytosolic complex composed of seven subunits, α- to ζ-coat proteins (COPs). For coat formation that initiates budding of a vesicle, ARF1 is recruited to the Golgi membrane from the cytosol in its GTP-bound form, and subsequently, coatomer can bind to the membrane. To identify a minimal structure of coatomer capable to bind to Golgi membranes in an ARF1-dependent manner, we have established a procedure to dissociate coatomer under conditions that allow reassociation of the subunits to a complete and functional complex. After dissociation, subunits or subcomplexes can be isolated and may be expected to be functional. Herein we describe isolation of a subcomplex of coatomer consisting of β- and δ-COPs that is able to bind to Golgi membranes in an ARF1- and GTP-dependent manner.
A family of membrane-embedded metalloproteases involved in regulated proteolysis of membrane-associated transcription factors
Authors: Rudner David Z. , Fawcett Paul , Losick Richard
Published: July 2002

We present evidence that the sporulation protein SpoIVFB of
Bacillus subtilis
is a member of a newly recognized family of metalloproteases that have catalytic centers adjacent to or within the membrane. SpoIVFB is required for converting the membrane-associated precursor protein, pro-σ
K
, to the mature and active transcription factor σ
K
by proteolytic removal of an N-terminal extension of 20 amino acids. SpoIVFB and other family members share the conserved sequence HEXXH, a hallmark of metalloproteases, as well as a second conserved motif NPDG, which is unique to the family. Both motifs, which are expected to form the catalytic center of the protease, overlap hydrophobic segments that are predicted to be separate transmembrane domains. The only other characterized member of this family of membrane-embedded metalloproteases is the mammalian Site-2 protease (S2P), which is required for the intramembrane cleavage of the eukaryotic transcription factor sterol regulatory element binding protein (SREBP). We report that amino acid substitutions in the two conserved motifs of SpoIVFB impair pro-σ
K
processing and σ
K
-directed gene expression during sporulation. These results and those from a similar analysis of S2P support the interpretation that both proteins are founding members of a family of metalloproteases involved in the activation of membrane-associated transcription factors. Thus, the pathways that govern the activation of the prokaryotic transcription factor pro-σ
K
and the mammalian transcription factor SREBP not only are analogous but also use processing enzymes with strikingly homologous features.
Molecular cloning of FOG-2: A modulator of transcription factor GATA-4 in cardiomyocytes
Authors: Svensson Eric C. , Tufts Rachel L. , Polk Christine E. , Leiden Jeffrey M.
Published: July 2002

GATA transcription factors are important regulators of both hematopoiesis (GATA-1/2/3) and cardiogenesis (GATA-4) in mammals. The transcriptional activities of the GATA proteins are modulated by their interactions with other transcription factors and with transcriptional coactivators and repressors. Recently, two related zinc finger proteins, U-shaped (USH) and Friend of GATA-1 (FOG) have been reported to interact with the GATA proteins Pannier and GATA-1, respectively, and to modulate their transcriptional activities
in vitro
and
in vivo
. In this report, we describe the molecular cloning and characterization of a third FOG-related protein, FOG-2. FOG-2 is an 1,151 amino acid nuclear protein that contains eight zinc finger motifs that are structurally related to those of both FOG and USH.
FOG-2
is first expressed in the mouse embryonic heart and septum transversum at embryonic day 8.5 and is subsequently expressed in the developing neuroepithelium and urogenital ridge. In the adult,
FOG-2
is expressed predominately in the heart, brain, and testis. FOG-2 associates physically with the N-terminal zinc finger of GATA-4 both
in vitro
and
in vivo
. This interaction appears to modulate specifically the transcriptional activity of GATA-4 because overexpression of FOG-2 in both NIH 3T3 cells and primary rat cardiomyocytes represses GATA-4-dependent transcription from multiple cardiac-restricted promoters. Taken together, these results implicate FOG-2 as a novel modulator of GATA-4 function during cardiac development and suggest a paradigm in which tissue-specific interactions between different FOG and GATA proteins regulate the differentiation of distinct mesodermal cell lineages.
Constitutive activation of tethered-peptide/ corticotropin-releasing factor receptor chimeras
Authors: Nielsen Søren Møller , Nielsen Lisa Z. , Hjorth Siv A. , Perrin Marilyn H. , Vale Wylie W.
Published: July 2002

Constitutive activity, or ligand-independent activity, of mutant G protein-coupled receptors (GPCRs) has been described extensively and implicated in the pathology of many diseases. Using the corticotropin-releasing factor (CRF) receptor and the thrombin receptor as a model, we present a ligand-dependent constitutive activation of a GPCR. A chimera in which the N-terminal domain of the CRF receptor is replaced by the amino-terminal 16 residues of CRF displays significant levels of constitutive activation. The activity, as measured by intracellular levels of cAMP, is blocked in a dose-dependent manner by the nonpeptide antagonist antalarmin. These results support a propinquity effect in CRF receptor activation, in which the amino-terminal portion of the CRF peptide is presented to the body of the receptor in the proper proximity for activation. This form of ligand-dependent constitutive activation may be of general applicability for the creation of constitutively activated GPCRs that are regulated by peptide ligands such as CRF. These chimeras may prove useful in analyzing mechanisms of receptor regulation and in the structural analysis of ligandactivated receptors.
Single chain spectroscopy of conformational dependence of conjugated polymer photophysics
Authors: Huser Thomas , Yan Ming , Rothberg Lewis J.
Published: July 2002

Single molecule confocal fluorescence microscopy was used to
perform photoluminescence spectroscopy on single, isolated molecules of
the conjugated polymer
poly[2-methoxy,5-(2′-ethyl-hexyloxy)-
p
-phenylene-vinylene]
(MEH-PPV). We show that the fluorescence from single chains of this
electroluminescent polymer depends strongly on chain conformation. The
time evolution of the spectra, emission intensity, and polarization all
provide direct evidence that memory of the chain conformation in
solution is retained after solvent evaporation. Chains cast from
toluene solution are highly folded and show memory of the excitation
polarization. Exciton funneling to highly aggregated low energy regions
causes the chain to mimic the photophysical behavior of a single
chromophore. Chains cast from chloroform, however, behave as
multichromophore systems, and no sudden discrete spectral or intensity
jumps are observed. These also exhibit different spectroscopy from the
folded chromophores.
Linear and nonlinear pathways of spectral information transmission in the cochlear nucleus
Authors: Yu Jane J. , Young Eric D.
Published: July 2002

At the level of the cochlear nucleus (CN), the auditory pathway
divides into several parallel circuits, each of which provides a
different representation of the acoustic signal. Here, the
representation of the power spectrum of an acoustic signal is analyzed
for two CN principal cells—chopper neurons of the ventral CN and type
IV neurons of the dorsal CN. The analysis is based on a weighting
function model that relates the discharge rate of a neuron to first-
and second-order transformations of the power spectrum. In chopper
neurons, the transformation of spectral level into rate is a linear
(i.e., first-order) or nearly linear function. This transformation is a
predominantly excitatory process involving multiple frequency
components, centered in a narrow frequency range about best frequency,
that usually are processed independently of each other. In contrast,
type IV neurons encode spectral information linearly only near
threshold. At higher stimulus levels, these neurons are strongly
inhibited by spectral notches, a behavior that cannot be explained by
level transformations of first- or second-order. Type IV weighting
functions reveal complex excitatory and inhibitory interactions that
involve frequency components spanning a wider range than that seen in
choppers. These findings suggest that chopper and type IV neurons form
parallel pathways of spectral information transmission that are
governed by two different mechanisms. Although choppers use a
predominantly linear mechanism to transmit tonotopic representations of
spectra, type IV neurons use highly nonlinear processes to signal the
presence of wide-band spectral features.
Epenthesis, Geminates, and the OCP in Finnish
Authors: Harrikari Heli
Published: July 2002

This study re-evaluates the representation of phonological length in
Finnish in the light of Optimality Theory. The Obligatory Contour Principle
(OCP) prohibits sequences of identical elements. It follows that long
segments cannot be represented as sequences of two short segments, but must
be interpreted monosegmentally (i.e. non-linearly). In Finnish, long
segments have been traditionally represented bisegmentally, consequently
violating the OCP. There are, however, phenomena in Finnish, such as
dialectal epenthesis, which pattern long consonants with short ones rather
than with bisegmental consonant clusters. This study provides an Optimality
Theoretic analysis for dialectal epenthesis, and shows that the analysis
predicts that monosegmental representation is the optimal way of
representing long consonants in Finnish as well.
Monitoring of immune activation using biochemical changes in a porcine model of cardiac arrest
Authors: Amann Anton , Widner Bernhard , Rieder Josef , Antretter Herwig , Hoffmann Georg , Mayr Viktoria , Strohmenger Hans-Ulrich , Fuchs Dietmar
Published: July 2002

In animal models, immune activation is often difficult to assess because of the limited availability of specific assays to detect cytokine activities. In human monocytes/macrophages, interferon‐γ induces increased production of neopterin and an enhanced activity of indoleamine 2,3‐dioxygenase, which degrades tryptophan via the kynurenine pathway. Therefore, monitoring of neopterin concentrations and of tryptophan degradation can serve to detect the extent of T helper cell 1‐type immune activation during cellular immune response in humans. In a porcine model of cardiac arrest, we examined the potential use of neopterin measurements and determination of the tryptophan degradation rate as a means of estimating the extent of immune activation. Urinary neopterin concentrations were measured with high‐performance liquid chromatography (HPLC) and radioimmunoassay (RIA) (BRAHMS Diagnostica, Berlin, Germany). Serum and plasma tryptophan and kynurenine concentrations were also determined using HPLC. Serum and urine neopterin concentrations were not detectable with HPLC in these specimens, whereas RIA gave weakly (presumably false) positive results. The mean serum tryptophan concentration was 39.0 Ī 6.2 μmol/l, and the mean kynurenine concentration was 0.85 Ī 0.33 μmol/l. The average kynurenine‐per‐tryptophan quotient in serum was 21.7Ī 8.4 nmol/μmol, and that in plasma was 20.7Ī 9.5 nmol/μmol (n = 7), which corresponds well to normal values in humans. This study provides preliminary data to support the monitoring of tryptophan degradation but not neopterin concentrations as a potential means of detecting immune activation in a porcine model. The kynurenine‐per‐tryptophan quotient may serve as a short‐term measurement of immune activation and hence permit an estimate of the extent of immune activation.
Complement activation by in vivo neonatal and in vitro extracorporeal membrane oxygenation
Authors: Graulich Johannes , Sonntag Joseph , Marcinkowski Monika , Bauer Karl , Kössel Hans , Bührer Christoph , Obladen Michael , Versmold Hans T.
Published: July 2002

Complement activation during extracorporeal membrane oxygenation (ECMO) in newborns can be caused by both the underlying disease processes and by blood contact with the ECMO circuit. We investigated the relative importance of these mechanisms by measuring C3a, C5a and sC5b‐9 before, during and after neonatal ECMO in six consecutive newborn patients using enzyme‐linked immunoassay. In addition complement activation during in vitro ECMO with repeated flow of the same blood volume was measured using blood from healthy adult donors. C3a increased significantly in vivo after 1 h (from 1035 ± 193 to 1865 ± 419 μg/l) and in vitro ECMO (from 314 ± 75 to 1962 ± 1062 μg/l). C5a increased during ECMO without significant differences between in vivo and
in vitro activation. In neonatal patients, sC5b‐9 rose faster than in vitro, but the rapid increase was also significant for in vitro experiments (in vivo: from 328 ± 63 to 1623 ± 387 μg/l after 2 h; and in vitro: from 78 ± 32 to 453 ± 179 μg/l after 8 h). After this initial peak at 1‐2 h, complement activation decreased gradually until 2‐3 days after the initiation of ECMO. We conclude that in newborns the rapid activation of the complement system after the start of ECMO is predominantly caused by contact with artificial surfaces rather than the patient′s underlying disease.
The neutrophil migration induced by tumour necrosis factor alpha in mice is unaffected by glucocorticoids
Authors: Cecilio C. A. , Costa E. H. , Ucelli P. , Chaves C. A. A. , Toffoli M. C. , Flores C. A. , Cunha F. Q. , Ferreira S. H. , Tamashiro W. M. S. C.
Published: July 2002

Macrophages harvested from the peritoneal cavities of rats release a neutrophil chemotactic factor (MNCF) in response to stimulation with Gram‐negative bacterial lipopolysaccharide (LPS). MNCF has been shown to be active in rats treated with dexamethasone, a glucocorticoid that usually inhibits the neutrophil migration induced in this species by interleukin (IL)‐1, tumour necrosis factor alpha (TNFα), IL‐8, C5a and leukotriene B4 (LTB4). Here we report that macrophages harvested from peritoneal cavities of mice, and stimulated in vitro with LPS, also release a factor that induces neutrophil migration in dexamethasone‐treated animals. This chemotactic activity was neutralized by the incubation of the LPS‐stimulated macrophage supernatants with a purified polyclonal IgG anti‐mouse TNFα. In addition, significant amounts of TNF were detected in the supernatants. The neutrophil migration induced by intraperitoneal administration of recombinant murine TNFα was also unaffected by pretreatment of the mice with dexamethasone. Moreover, neutrophil migration induced by intraperitoneal injection of LPS was completely blocked by pretreatment of the mice with a monoclonal antibody against murine TNFα. In conclusion, our results support the hypothesis that, in contrast to the role of TNF in rats (where it indirectly induces neutrophil migration), in mice, it may be an important mediator in the recruitment of neutrophils to
inflammatory sites.
Reduction of nitric oxide release from alveolar macrophages by a lipocortin peptide
Authors: Kamal A. M. , Tetley T. D. , Witherden I. R. , Smith S. F.
Published: July 2002

Nitric oxide (NO), produced by alveolar macrophages (AM) is used as a marker of respiratory tract inflammation. Lipocortin 1 (Lc‐1) is an anti‐inflammatory, glucocorticoid‐inducible protein. The current aims were to determine whether (a) an Lc‐1‐derived peptide, Ac2‐26, inhibited lipopolysaccharide (LPS)induced NO release by primary AM in vitro and (b) the inhibitory action of dexamethasone was Lc‐1‐dependent. LPS treatment stimulated NO release from rat AM. Ac2‐26 had little effect on unstimulated release, but suppressed LPS‐stimulated release at concentrations of 320 nM (320 nM, 10 ± 3%; 3.2 μ M, 15 ± 3%; 32 μ M, 27 ± 4% NO inhibited, mean ± SEM, n = 6). Inhibition by dexamethasone of NO release was unaffected by neutralizing anti‐Lc‐1 indicating that this action is Lc1‐independent in primary AM. Nevertheless inhibition of NO release by Ac2‐26 (80 μ M) was similar to that of 1 μ M dexamethasone (Ac2‐26, 40 ± 6%; dexamethasone, 48 ± 6% NO inhibited, mean ± SEM, n = 6).
Public service broadcasting in Italy: Historical trends and future prospects
Authors: Hibberd Matthew
Published: July 2002

The article outlines the current structure and organization of public service broadcasting in Italy and explores various options for its future development. With moves towards digital broadcasting, RAI is set to enter a discrete next stage which will bring new challenges and will inevitably lead to a revision of its public service remit. While it is currently unclear how far Italian public service broadcasting will change, there is evidence that members of the government and senior RAI managers wish partially to privatize core elements of its public service. Focusing on the development of television, the article addresses some of the salient issues facing RAI and other public service broadcasters who have become the victims of a pervasive disenchantment with public provision of goods and services.
The Dynamic Nuclear Redistribution of an hnRNP K-homologous Protein during Drosophila Embryo Development and Heat Shock. Flexibility of Transcription Sites In Vivo
Authors: Buchenau Peter , Saumweber Harald , Arndt-Jovin Donna J.
Published: July 2002

The Drosophila protein Hrb57A has sequence homology to mammalian heterogenous nuclear ribonucleoprotein (hnRNP) K proteins. Its in vivo distribution has been studied at high resolution by confocal laser scanning microscopy (CLSM) in embryos injected with fluorescently labeled monoclonal antibody. Injection of antibody into living embryos had no apparent deleterious effects on further development. Furthermore, the antibody-protein complex could be observed for more than 7 cell cycles in vivo, revealing a dynamic redistribution from the nucleus to cytoplasm at each mitosis from blastoderm until hatching. The evaluation of two- and three-dimensional CLSM data sets demonstrated important differences in the localization of the protein in the nuclei of living compared to fixed embryos. The Hrb57A protein was recruited to the 93D locus upon heat shock and thus serves as an in vivo probe for the activity of the gene in diploid cells of the embryo. Observations during heat shock revealed considerable mobility within interphase nuclei of this transcription site. Furthermore, the reinitiation as well as the down regulation of transcriptional loci in vivo during the recovery from heat shock could be followed by the rapid redistribution of the hnRNP K during stress recovery. These data are incompatible with a model of the interphase nucleus in which transcription complexes are associated with a rigid nuclear matrix.
Histamine treatment induces rearrangements of orthogonal arrays of particles (OAPs) in human AQP4-expressing gastric cells
Authors: Carmosino Monica , Procino Giuseppe , Nicchia Grazia Paola , Mannucci Roberta , Verbavatz Jean-Marc , Gobin Renèe , Svelto Maria , Valenti Giovanna
Published: July 2002

To test the involvement of the water channel aquaporin (AQP)-4 in gastric acid physiology, the human gastric cell line (HGT)-1 was stably transfected with rat AQP4. AQP4 was immunolocalized to the basolateral membrane of transfected HGT-1 cells, like in native parietal cells. Expression of AQP4 in transfected cells increased the osmotic water permeability coefficient (Pf) from 2.02 ± 0.3 × 10−4 to 16.37 ± 0.5 × 10−4 cm/s at 20°C. Freeze-fracture EM showed distinct orthogonal arrays of particles (OAPs), the morphological signature of AQP4, on the plasma membrane of AQP4-expressing cells. Quantitative morphometry showed that the density of OAPs was 2.5 ± 0.3% under basal condition and decreased by 50% to 1.2 ± 0.3% after 20 min of histamine stimulation, mainly due to a significant decrease of the OAPs number. Concomitantly, Pf decreased by ∼35% in 20-min histamine-stimulated cells. Both Pf and OAPs density were not modified after 10 min of histamine exposure, time at which the maximal hormonal response is observed. Cell surface biotinylation experiments confirmed that AQP4 is internalized after 20 min of histamine exposure, which may account for the downregulation of water transport. This is the first evidence for short term rearrangement of OAPs in an established AQP4-expressing cell line.
Negative Signaling Pathways of the Killer Cell Inhibitory Receptor and FcγRIIb1 Require Distinct Phosphatases
Authors: Gupta Neetu , Scharenberg Andrew M. , Burshtyn Deborah N. , Wagtmann Nicolai , Lioubin Mario N. , Rohrschneider Larry R. , Kinet Jean-Pierre , Long Eric O.
Published: July 2002

Inhibition of natural killer (NK) cells by the killer cell inhibitory receptor (KIR) involves recruitment of the tyrosine phosphatase SHP-1 by KIR and is prevented by expression of a dominant negative SHP-1 mutant. Another inhibitory receptor, the low affinity Fc receptor for immunoglobulin G (IgG) (FcγRIIb1), has been shown to bind SHP-1 when cocross-linked with the antigen receptor on B cells (BCR). However, coligation of FcγRIIb1 with BCR and with FcεRI on mast cells leads to recruitment of the inositol 5′ phosphatase SHIP and to inhibition of mast cells from SHP-1–deficient mice. In this study, we evaluated the ability of these two inhibitory receptors to block target cell lysis by NK cells, and the contribution of SHP-1 and SHIP to inhibition. Recombinant vaccinia viruses encoding chimeric receptors and dominant negative mutants of SHP-1 and SHIP were used for expression in mouse and human NK cells. When the KIR cytoplasmic tail was replaced by that of FcγRIIb1, recognition of HLA class I on target cells by the extracellular domain resulted in inhibition. A dominant negative mutant of SHP-1 reverted the inhibition mediated by the KIR cytoplasmic tail but not that mediated by FcγRIIb1. In contrast, a dominant negative mutant of SHIP reverted only the inhibition mediated by the FcγRIIb1 tail, providing functional evidence that SHIP plays a role in the FcγRIIb1-mediated negative signal. These data demonstrate that inhibition of NK cells by KIR involves primarily the tyrosine phosphatase SHP-1, whereas inhibition mediated by FcγRIIb1 requires the inositol phosphatase SHIP.
Functional Separation of Pseudopod Extension and Particle Internalization during Fcγ Receptor–mediated Phagocytosis
Authors: Lowry Malcolm B. , Duchemin Anne-Marie , Robinson John M. , Anderson Clark L.
Published: July 2002

Receptors for the Fc portion of immunoglobulin (Ig)G (FcγR) mediate phagocytosis of IgG-opsonized particles by a process that can be divided into four major steps: receptor–ligand binding, pseudopod extension, internalization, and lysosomal fusion. We have expressed single classes of FcγR in COS fibroblasts to examine the structural determinants necessary to complete the four steps of phagocytosis. Using phase contrast, fluorescence, confocal, and electron microscopy we have demonstrated that FcγR-expressing COS cells can phagocytose in a manner similar to that of professional phagocytes. We have further analyzed the capacity of the three classes of FcγR to phagocytose, placing special emphasis on the FcγRIA–γ chain complex, which allowed us to examine independently the roles of the ligand-binding unit (FcγRIA) and the signaling unit (γ chain). We found that receptor complexes containing a conserved tyrosine activation motif (ITAM), as found in the cytoplasmic domain of FcγRIIA and in the γ chain associated with FcγRIA and FcγRIIIA, readily internalized target particles. In contrast, FcγRIA alone, having no ITAM, was unable to internalize target particles efficiently, but did mediate pseudopod extension. Cotransfection of γ chain with FcγRIA restored the ability of the receptor to internalize target particles. A mutant FcγRIA in which the cytoplasmic domain had been deleted was also capable of mediating pseudopod extension, showing that neither the γ chain nor the cytoplasmic domain of FcγRIA were required for this step. Cytochalasin D, an inhibitor of actin polymerization, blocked particle internalization by all FcγR, but did not block pseudopod extension. Staining the FcγRIA COS cells for F-actin and for tyrosine phosphoproteins, we found that actin did not polymerize during FcγRIA-mediated pseudopod extension, nor were tyrosine kinases activated. Our data suggest that pseudopod extension and internalization are functionally distinct steps mediated through different pathways.
Immune Suppression by Recombinant Interleukin (rIL)-12 Involves Interferon γ Induction of Nitric Oxide Synthase 2 (iNOS) Activity: Inhibitors of NO Generation Reveal the Extent of rIL-12 Vaccine Adjuvant Effect
Authors: Koblish Holly Kurzawa , Hunter Christopher A. , Wysocka Maria , Trinchieri Giorgio , Lee William M.F.
Published: July 2002

Recombinant interleukin 12 (IL-12) can profoundly suppress cellular immune responses in mice. To define the underlying mechanism, recombinant murine (rm)IL-12 was given to C57BL/6 mice undergoing alloimmunization and found to transiently but profoundly suppress in vivo and in vitro allogeneic responses and in vitro splenocyte mitogenic responses. Use of neutralizing antibodies and genetically deficient mice showed that IFN-γ (but not TNF-α) mediated rmIL-12–induced immune suppression. Splenocyte fractionation studies revealed that adherent cells from rmIL-12–treated mice suppressed the mitogenic response of normal nonadherent cells to concanavalin A and IL-2. Addition of an inhibitor of nitric oxide synthase (NOS) restored mitogenic responses, and inducible (i)NOS−/− mice were not immunosuppressed by rmIL-12. These results support the view that suppression of T cell responses is due to NO produced by macrophages responding to the high levels of IFN-γ induced by rmIL-12. When a NOS inhibitor was given with rmIL-12 during vaccination of A/J mice with irradiated SCK tumor cells, immunosuppression was averted and the extent of rmIL-12's ability to enhance induction of protective antitumor immunity was revealed. This demonstrates that rmIL-12 is an effective vaccine adjuvant whose efficacy may be masked by its transient immunosuppressive effect.
B7-1 or B7-2 Is Required to Produce the Lymphoproliferative Phenotype in Mice Lacking Cytotoxic T Lymphocyte–associated Antigen 4 (CTLA-4)
Authors: Mandelbrot Didier A. , McAdam Alexander J. , Sharpe Arlene H.
Published: July 2002

The costimulatory molecules B7-1 and B7-2 regulate T lymphocyte activation by delivering activating signals through CD28 and inhibitory signals through cytotoxic T lymphocyte–associated antigen 4 (CTLA-4). The importance of CTLA-4–mediated inhibition was demonstrated by the uncontrolled T cell activation and lymphoproliferative disease that develops in CTLA-4–deficient (−/−) mice. To examine the role of B7 signaling in the activation of CTLA-4–deficient T cells, we bred CTLA-4−/− mice with mice lacking B7-1, B7-2, or both B7 molecules. The CTLA-4/B7-1−/− and the CTLA-4/B7-2−/− mice develop lymphoproliferation and enhanced T cell activation. Mice lacking CTLA-4, B7-1, and B7-2 have a normal life-span, and do not have lymphocytic infiltrates in any organs, or increased T cell activation. Therefore, the two B7 molecules have overlapping functions, since either B7-1 or B7-2 alone can cause the CTLA-4−/− phenotype. Elimination of both B7-1 and B7-2 from the CTLA-4– deficient mouse abrogates the lymphocyte activation and disease, and does not reveal evidence for additional stimulatory CD28 ligands. The CTLA-4−/− phenotype can be reproduced with anti-CD28 antibody in mice lacking CTLA-4, B7-1, and B7-2, but wild-type mice are unaffected by the same treatment. This suggests that the inhibitory function of CTLA-4 can overcome strong CD28-mediated signaling in vivo.
Structure of Human Histocompatibility Leukocyte Antigen (Hla)-Cw4, a Ligand for the Kir2d Natural Killer Cell Inhibitory Receptor
Authors: Fan Qing R. , Wiley Don C.
Published: July 2002

The crystal structure of the human class I major histocompatibility complex molecule, human histocompatibility leukocyte antigen (HLA)-Cw4, the ligand for a natural killer (NK) cell inhibitory receptor, has been determined, complexed with a nonameric consensus peptide (QYDDAVYKL). Relative to HLA-A2, the peptide binding groove is widened around the COOH terminus of the α1 helix, which contains residues that determine the specificity of HLA-Cw4 for the inhibitory NK receptor, KIR2D. The structure reveals an unusual pattern of internal hydrogen bonding among peptide residues. The peptide is anchored in four specificity pockets in the cleft and secured by extensive hydrogen bonds between the peptide main chain and the cleft. The surface of HLA-Cw4 has electrostatic complementarity to the surface of the NK cell inhibitory receptor KIR2D.
Bruton's Tyrosine Kinase Regulates the Activation of Gene Rearrangements at the λ Light Chain Locus in Precursor B Cells in the Mouse
Authors: Dingjan Gemma M. , Middendorp Sabine , Dahlenborg Katarina , Maas Alex , Grosveld Frank , Hendriks Rudolf W.
Published: July 2002

Bruton's tyrosine kinase (Btk) is a nonreceptor tyrosine kinase involved in precursor B (pre-B) cell receptor signaling. Here we demonstrate that Btk-deficient mice have an ∼50% reduction in the frequency of immunoglobulin (Ig) λ light chain expression, already at the immature B cell stage in the bone marrow. Conversely, transgenic mice expressing the activated mutant BtkE41K showed increased λ usage. As the κ/λ ratio is dependent on (a) the level and kinetics of κ and λ locus activation, (b) the life span of pre-B cells, and (c) the extent of receptor editing, we analyzed the role of Btk in these processes. Enforced expression of the Bcl-2 apoptosis inhibitor did not alter the Btk dependence of λ usage. Crossing 3-83μδ autoantibody transgenic mice into Btk-deficient mice showed that Btk is not essential for receptor editing. Also, Btk-deficient surface Ig+ B cells that were generated in vitro in interleukin 7-driven bone marrow cultures manifested reduced λ usage. An intrinsic defect in λ locus recombination was further supported by the finding in Btk-deficient mice of reduced λ usage in the fraction of pre-B cells that express light chains in their cytoplasm. These results implicate Btk in the regulation of the activation of the λ locus for V(D)J recombination in pre-B cells.
L-Selectin Shedding Regulates Leukocyte Recruitment
Authors: Hafezi-Moghadam Ali , Thomas Kennard L. , Prorock Alyson J. , Huo Yuqing , Ley Klaus
Published: July 2002

The physiologic role of L-selectin shedding is unknown. Here, we investigate the effect of L-selectin shedding on firm adhesion and transmigration. In a tumor necrosis factor α–induced model of inflammation, inhibition of L-selectin shedding significantly increased firm adhesion and transmigration by a lymphocyte function–associated antigen (LFA)-1 and intercellular adhesion molecule (ICAM)-1–dependent mechanism. We examined the quality of leukocyte rolling and L-selectin–mediated signaling. Blockade of L-selectin shedding significantly reduced the “jerkiness” of leukocyte rolling, defined as the variability of velocity over time. A low level of jerkiness was also observed in the rolling of microbeads conjugated with L-selectin, a model system lacking the mechanism for L-selectin shedding. Inhibition of L-selectin shedding potentiated activation of LFA-1 and Mac-1 induced by L-selectin cross-linking as shown by activation epitope expression and binding of ICAM-1–conjugated beads. We conclude that inhibition of L-selectin shedding increases leukocyte adhesion and transmigration by (a) increasing leukocyte exposure to the inflamed endothelium by decreasing jerkiness and (b) promoting leukocyte activation by outside-in signaling. These observations help to resolve the apparent discrepancy between the minor contribution of L-selectin to rolling and the significant leukocyte recruitment defect in L-selectin knockout mice.
Mordell-Weil groups of the Jacobian of the 5-th Fermat curve
Authors: Tzermias Pavlos
Published: July 2002

Let

J

5

J_{5}

denote the Jacobian of the Fermat curve of exponent 5 and let

K
=
Q
(

ζ

5

)

K=Q(\zeta _{5})

. We compute the groups

J

5

(
K
)

J_{5}(K)

,

J

5

(

K

+

)

J_{5}(K^{+})

,

J

5

(
Q
)

J_{5}(Q)

, where

K

+

K^{+}

is the unique quadratic subfield of

K
K

. As an application, we present a new proof that there are no

K
K

-rational points on the 5-th Fermat curve, except the so called “points at infinity".
Computing Stark units for totally real cubic fields
Authors: Dummit David , Sands Jonathan , Tangedal Brett
Published: July 2002

A method for computing provably accurate values of partial zeta functions is used to numerically confirm the rank one abelian Stark Conjecture for some totally real cubic fields of discriminant less than 50000. The results of these computations are used to provide explicit Hilbert class fields and some ray class fields for the cubic extensions.
RRTree: Relative-Rate Tests between groups of sequences on a
phylogenetic tree
Authors: Robinson-Rechavi Marc , Huchon Dorothée
Published: July 2002

*To whom correspondence should be addressed.

3Present address: Laboratoire de Biologie Moléculaire et Cellulaire, Ecole Normale Supérieure de Lyon, 6 allée d’Italie, 69364 Lyon cedex 07, France, marc.robinson@ens-lyon.fr

Summary: RRTree is a user-friendly program for comparing substitution rates between lineages of protein or DNA sequences, relative to an outgroup, through relative rate tests. Genetic diversity is taken into account through use of several sequences, and phylogenetic relations are integrated by topological weighting.

Availability: The ANSI C source code of RRTree, and compiled versions for Macintosh, MS-DOS/Windows, SUN Solaris, and CGI, are freely available at http://pbil.univ-lyon1.fr/software/rrtree.html

Contact: marc.robinson@ens-lyon.fr
Revisiting Business Historians and the Internet
Authors: Kerr K. Austin
Published: July 2002

During the 1996 annual meeting of the Business History Conference, a
session on the World Wide Web attracted considerable attention from curious
members (see Business and Economic History 25
[Fall 1996]: 46—54). The Internet was then somewhat of an infant, and most
of us, just becoming accustomed to the speed and convenience of electronic
mail, were barely aware of the opportunities afforded by the then-new
graphical interface known as the Web. No more! At least not in the United
States, where advertisers bombard us with their Internet addresses and news
accounts inform us of vast fortunes made in new Internet ventures that have
not yet turned a profit. There is, in short, a “dot.com” revolution
occurring in American business. It is also happening, albeit more slowly, in
scholarly and educational circles.
‘Carry Your Credit in Your Pocket’: The Early History of the Credit Card at Bank of America and Chase Manhattan
Authors: Wolters Timothy
Published: July 2002

Drawing from newly available archival material, this article explores the early history of one of today’s most ubiquitous financial instruments, the bank credit card. It focuses on the managerial decisions that led to the implementation and development of charge card programs at the two largest American banks of the late 1950s and early 1960s. Even though the initial performance of the two programs was comparable, top management at each bank ultimately adopted different business strategies. The differences resulted from managers’ contrasting interpretations of the appropriate market for the credit card, interpretations formed within the context of two distinct banking cultures.
British Public Policy and Multinationals during the “Dollar Gap” Era, 1945–1960
Authors: Rooth Tim , Scott Peter
Published: July 2002

This article examines the role of British exchange and import controls in stimulating the dramatic increase in overseas (particularly American) multinationals in Britain from the end of the Second World War to the late 1950s, together with the ways in which the government used controls to regulate the foreign direct investment (FDI) inflow. Exchange controls were both an important stimulus to inward investment and a powerful and flexible means of regulating its volume and character. Government was relatively successful in using these powers to maximize the dollar balance and industrial benefits of FDI to Britain, given initially severe dollar and capacity constraints, and in liberalizing policy once these constraints receded and competition from other FDI hosts intensified.
Marketing in the Land of Hudson Bay: Indian Consumers and the Hudson's Bay Company, 1670–1770
Authors: Carlos Ann M. , Lewis Frank D.
Published: July 2002

The Hudson's Bay Company traded European goods for furs that were hunted, trapped, and brought down to the Bayside posts by Native Americans. The process of exchange was deceptively simple: furs for goods. Yet behind this simple process lies a series of decisions on the part of the company about which goods to provide, what levels of quality to provide, and what price to set. We examine the marketing strategies used by the Hudson's Bay Company and the role played by Native traders. We find that Native Americans were demanding consumers, concerned not only with the quantity of goods they received but also with their quality and variety. In a world where neither side could coerce the other, Natives' preferences were paramount.
Working Memory for Temporal and Nontemporal Events in Monkeys
Authors: Sakurai Yoshio
Published: July 2002

This is the first report that introduces appropriate behavioral tasks for monkeys for investigations of working memory for temporal and nontemporal events. Using several behavioral tests, the study also shows how temporal information is coded during retention intervals in the tasks. Each of three monkeys was trained with two working memory tasks: delayed matching-to-sample of stimulus duration (DMS-D) and delayed matching-to-sample of stimulus color (DMS-C). The two tasks employed an identical apparatus and responses and differed only in the temporal and nontemporal attribute of the stimuli to be retained for correct performance. When a retention interval between the sample and comparison stimuli was prolonged, the monkeys made more incorrect responses to short samples in the DMS-C task, suggesting “trace decay” of memory for short stimuli. However, the same monkeys showed no such increase in incorrect responses to short samples in the DMS-D task, suggesting active coding of temporal information, that is, the length of stimulus duration, during the retention interval. When variable lengths of samples were presented with a fixed retention interval, the monkeys made more incorrect responses when length differences between short and long samples were small in the DMS-D task, but not in the DMS-C task. This suggests that the codes of working memory retained in the DMS-D task were not absolute (analogical) but rather were relative (categorical) and related to differences in the duration of the samples.
Application of the new MultiTrans radiation transport code in BNCT dose planning
Authors: Kotiluoto Petri , Hiismäki Pekka , Savolainen Sauli
Published: July 2002

Dose planning in boron neutron capture therapy (BNCT) is a complex problem and requires sophisticated numerical methods. In the framework of the Finnish BNCT project, new deterministic three‐dimensional radiation transport code MultiTrans has been developed at VTT Chemical Technology, based on a novel application of the tree multigrid technique. To test the applicability of this new code in a realistic BNCT dose planning problem, cylindrical PMMA (polymethyl‐methacrylate) phantom was chosen as a benchmark case. It is a convenient benchmark, as it has been modeled by several different codes, including well‐known DORT and MCNP. Extensive measured data also exist. In this paper, a comparison of the new MultiTrans code with other methods is presented for the PMMA phantom case. Results show that the total neutron dose rate to ICRU adult brain calculated by the MultiTrans code differs less than 4% in 2 cm depth in phantom (in thermal maximum) from the DORT calculation. Results also show that the calculated and reaction rates in 2 cm depth in phantom differ less than 4% and 1% from the measured values, respectively. However, the photon dose calculated by the MultiTrans code seems to be incorrect in this PMMA phantom case, which requires further studying. As expected, the deterministic MultiTrans code is over an order of magnitude faster than stochastic Monte Carlo codes (with similar resolution), thus providing a very efficient tool for BNCT dose planning.
Improved computed radiography image quality from a BaFI:Eu photostimulable phosphor plate
Authors: Nakano Yasushi , Gido Tomonori , Honda Satoshi , Maezawa Akihiro , Wakamatsu Hideaki , Yanagita Takafumi
Published: July 2002

Recent advances in the design of photostimulable phosphor (PSP) plates for computed radiography (CR) systems have made it possible to manufacture plates made of BaFI:Eu phosphor material in the cassette form. The image quality of this plate, six BaF(Br,I):Eu plates, and one BaFBr:Eu plate were evaluated in terms of presampling modulation transfer function (MTF), normalized Wiener spectra and detective quantum efficiency (DQE). Compared with the best‐performing BaF(Br,I):Eu plate, the BaFI:Eu plate provided DQE that was higher, at spatial frequencies of 0.5, 1.0, and 2.0 cycles/mm, by 12% (21.8 versus 19.4), 13% (18.8 versus 16.7), and 11% (12.0 versus 10.8), respectively. Since presampling MTF values of the two plates were comparable, the BaFI:Eu plate's higher DQE is attributable to total conversely being lower by 17% versus 17% versus and 12% versus at the specified frequencies, respectively, primarily due to the contribution of x‐ray quantum This jibes with the high x‐ray absorption provided by the 27%‐higher x‐ray attenuation coefficients (7.54 versus 6.07, at 60 KeV) that BaFI offers over a result of the high atomic number of BaFI's exclusively iodine halide content. The results were consistent with earlier studies of several of these same plates and indicate that BaFI:Eu is a promising avenue to lower image noise and higher overall CR system image quality.
Incorporation of realistic delivery limitations into dynamic MLC treatment delivery
Authors: Litzenberg Dale W. , Moran Jean M. , Fraass Benedick A.
Published: July 2002

The clinical implementation of IMRT involves the use of a number of complex software‐based systems, typically including an inverse planning system, a leaf sequencer, and a computer‐controlled treatment delivery system. The inverse planning system determines the desired fluence patterns, the leaf sequencer translates those fluence maps into leaf trajectories, and the control system delivers those trajectories. While verification of intensity‐modulated treatment fields has focused primarily on the dosimetric aspects of delivery, accurate delivery of the intended fluence distribution is dependent upon both the leaf sequencer and delivery control systems. Leaf sequencing algorithms typically do not incorporate many control system limitations, and this can lead to discrepancies between planned and delivered sequences. In this work, simple and complex fields were sequenced for the dynamic sliding window technique using different leaf speeds and tolerance settings to identify various limitations of the accelerator control system. This work was conducted on a Varian 2100 EX equipped with a Millennium 120 leaf MLC. The identified limitations were then incorporated into the sequencing algorithm using a limiting leaf velocity (less than the maximum leaf velocity), the leaf position tolerance, and the communications delay in the control system. Collision avoidance in leaf pairs was found to depend on a control system‐enforced minimum gap between leaves and led to acceleration effects. By incorporating these effects into the leaf sequencing algorithm, dynamic sliding‐window leaf sequences were produced which did not require beam interruptions or dose rate modulations for the parameter values used in calculating the sequence (dose rate, tolerance, leaf speed, and total monitor units). Incorporation of control system limitations into the leaf sequencing algorithm results in IMRT fields that are delivered with the prescribed constant dose rate, require less time to deliver, and have well‐defined, calculable transmission dose characteristics.