bluuebunny/crossref_metadata_2025 huggingface dataset:
A macromolecular delivery vehicle for protein-based vaccines: Acid-degradable protein-loaded microgels
Authors: Murthy Niren , Xu Mingcheng , Schuck Stephany , Kunisawa Jun , Shastri Nilabh , Fréchet Jean M. J.
Published: April 2003

The development of protein-based vaccines remains a major challenge in the fields of immunology and drug delivery. Although numerous protein antigens have been identified that can generate immunity to infectious pathogens, the development of vaccines based on protein antigens has had limited success because of delivery issues. In this article, an acid-sensitive microgel material is synthesized for the development of protein-based vaccines. The chemical design of these microgels is such that they degrade under the mildly acidic conditions found in the phagosomes of antigen-presenting cells (APCs). The rapid cleavage of the microgels leads to phagosomal disruption through a colloid osmotic mechanism, releasing protein antigens into the APC cytoplasm for class I antigen presentation. Ovalbumin was encapsulated in microgel particles, 200–500 nm in diameter, prepared by inverse emulsion polymerization with a synthesized acid-degradable crosslinker. Ovalbumin is released from the acid-degradable microgels in a pH-dependent manner; for example, microgels containing ovalbumin release 80% of their encapsulated proteins after 5 h at pH 5.0, but release only 10% at pH 7.4. APCs that phagocytosed the acid-degradable microgels containing ovalbumin were capable of activating ovalbumin-specific cytoxic T lymphocytes. The acid-degradable microgels developed in this article should therefore find applications as delivery vehicles for vaccines targeted against viruses and tumors, where the activation of cytoxic T lymphocytes is required for the development of immunity.
Virus-like interference in the latency and prevention of Creutzfeldt–Jakob disease
Authors: Manuelidis Laura , Lu Zhi Yun
Published: April 2003

We previously showed that intracerebral (ic) inoculation of the attenuated SY strain of Creutzfeld–Jakob disease in mice could delay clinical signs and widespread neuropathology evoked by subsequent ic challenge with the more virulent FU strain. Using lower doses of SY and FU ic, we here demonstrate that mice can be protected well into old age without demonstrable neuropathology or pathologic prion protein (PrP-res). In contrast, parallel FU only controls became terminally diseased 1 year earlier. To determine whether factors elaborated in response to SY might be part of this effect, we evaluated brain and serum samples from additional parallel mice at 90 days after SY infection and just before FU challenge. The infectivity of FU preparations was significantly reduced by mixing with these fresh SY brain homogenates but not by mixing with SY serum samples, suggesting that brain cells were elaborating labile inhibitory factors that were part of the protective response. SY infectivity was too low to be detected in these brain homogenates. Although suppression could be overcome by higher FU doses ic, strong protection against maximal doses of FU was observed by using i.v. inoculations. Because myeloid microglia are infectious and also elaborate many factors in response to the foreign Creutzfeld–Jakob disease agent, it is likely that innate immunity underlies the profound protection shown here. In principle, it should be possible to artificially stimulate relevant myeloid pathways to better prevent and/or delay the clinical and pathological sequelae of these infections.
Delivery of bioactive molecules to mitochondria
in
vivo
Authors: Smith Robin A. J. , Porteous Carolyn M. , Gane Alison M. , Murphy Michael P.
Published: April 2003

Mitochondrial dysfunction contributes to many human degenerative diseases but specific treatments are hampered by the difficulty of delivering bioactive molecules to mitochondria
in vivo
. To overcome this problem we developed a strategy to target bioactive molecules to mitochondria by attachment to the lipophilic triphenylphosphonium cation through an alkyl linker. These molecules rapidly permeate lipid bilayers and, because of the large mitochondrial membrane potential (negative inside), accumulate several hundredfold inside isolated mitochondria and within mitochondria in cultured cells. To determine whether this strategy could lead to the development of mitochondria-specific therapies, we investigated the administration and tissue distribution in mice of simple alkyltriphenylphosphonium cations and of mitochondria-targeted antioxidants comprising a triphenylphosphonium cation coupled to a coenzyme Q or vitamin E derivative. Significant doses of these compounds could be fed safely to mice over long periods, coming to steady-state distributions within the heart, brain, liver, and muscle. Therefore, mitochondria-targeted bioactive molecules can be administered orally, leading to their accumulation at potentially therapeutic concentrations in those tissues most affected by mitochondrial dysfunction. This finding opens the way to the testing of mitochondria-specific therapies in mouse models of human degenerative diseases.
A sensitive, versatile microfluidic assay for bacterial chemotaxis
Authors: Mao Hanbin , Cremer Paul S. , Manson Michael D.
Published: April 2003

We have developed a microfluidic assay for bacterial chemotaxis in which a gradient of chemoeffectors is established inside a microchannel via diffusion between parallel streams of liquid in laminar flow. The random motility and chemotactic responses to
l
-aspartate,
l
-serine,
l
-leucine, and Ni
2+
of WT and chemotactic-mutant strains of
Escherichia coli
were measured. Migration of the cells was quantified by counting the cells accumulating in each of 22 outlet ports. The sensitivity of the assay is attested to by the significant response of WT cells to 3.2 nM
l
-aspartate, a concentration three orders of magnitude lower than the detection limit in the standard capillary assay. The response to repellents was as robust and easily recorded as the attractant response. A surprising discovery was that
l
-leucine is sensed by Tar as an attractant at low concentrations and by Tsr as a repellent at higher concentrations. This assay offers superior performance and convenience relative to the existing assays to measure bacterial tactic responses, and it is flexible enough to be used in a wide range of different applications.
PD-L1 and PD-L2 are differentially regulated by Th1 and Th2 cells
Authors: Loke P'ng , Allison James P.
Published: April 2003

PD-L1 and PD-L2 are ligands for PD-1, a costimulatory molecule that plays an inhibitory role in regulating T cell activation in the periphery. We find that PD-L1 is highly expressed on inflammatory macrophages as compared with resident peritoneal macrophages but can be induced on resident macrophages by classical activation stimuli such as lipopolysaccharide, IFN-γ, and polyinosinic-polycytidylic acid. Further up-regulation of PD-L1 on inflammatory macrophages can also be induced by subsequent exposure to lipopolysaccharide and IFN-γ. In contrast, PD-L2 is not expressed on inflammatory macrophages but can be induced by alternative activation via IL-4. Although PD-L1 is highly inducible on a variety of antigen-presenting cell lines as well as resident macrophages, PD-L2 is most significantly inducible only on inflammatory macrophages. PD-L1 up-regulation depends on TLR4 and STAT1, whereas PD-L2 expression depends on IL-4Rα and STAT6. Consistent with these results, T helper 1/T helper 2 (Th1/Th2) cells also differentially up-regulate PD-L1 and PD-L2 expression on inflammatory macrophages. Hence, Th1 cells as well as microbial products can enhance PD-L1 expression on many different macrophage populations, whereas Th2 cells instruct only inflammatory macrophages to up-regulate PD-L2. These results suggest that PD-L1 and PD-L2 might have different functions in regulating type 1 and type 2 responses.
Cancer cachexia: Its correlations and causes
Authors: Rubin Harry
Published: April 2003

Cancer cachexia involves the loss of weight, mainly in skeletal muscle and adipose tissue, that is not caused simply by anorexia. The syndrome includes anemia and immunosuppression along with a number of biochemical changes indicating systemic effects of the cancer. It is a major factor in morbidity and mortality from cancer. For 30 years beginning in 1948, a large number of studies reported isolation from many tumors of a heterogeneous group of small peptides, generally labeled toxohormone, that caused various correlates of cachexia shortly after injection into mice. Interest in toxohormone-like peptides then fell off for diverse reasons that had little to do with their clinical significance and was shifted to cytokines, ILs, and ectopic hormones with catabolic consequences that were sporadically found in tumors. At the same time, evidence was accumulating for an important role of pericellular proteases in driving progressive stages of neoplastic development. A central part of that evidence was the inhibition of transformation-related changes by protease inhibitors, particularly the combination present in fetal bovine serum, which fully suppressed the expression of the transformed phenotype in discrete foci of chicken embryo fibroblasts (CEF) infected by Rous sarcoma virus against a confluent background of uninfected CEF. In contrast, CEF cultures heavily infected with Rous sarcoma virus in the same medium underwent pervasive transformation, which was correlated with the release of low molecular weight cytotoxic substances. Reevaluation of all of the evidence supports a central role for proteolytically generated peptides derived from tumors in producing cancer cachexia.
Selective heteromeric assembly of cyclic nucleotide-gated channels
Authors: Zhong Haining , Lai Jun , Yau King-Wai
Published: April 2003

Many ion channels
in vivo
are heteromeric complexes with well defined subunit compositions. For some channels, domains have been identified that determine whether two or more subunit species are compatible in forming a complex. Nonetheless, an unsolved fundamental question is how the native composition of an ion channel is selected during assembly over functional alternatives, such as heteromeric complexes favored over homomers. Cyclic nucleotide-gated channels are tetramers and, in their native forms, are composed of A and B subunits. Although most A subunits can form functional homomeric channels when expressed alone, A/B heteromeric channels are selectively formed in the presence of a B subunit. Here, we show that this selective assembly of heteromeric channels requires a trimer-forming C-terminal leucine zipper (CLZ) domain recently identified in the distal C terminus of A, but not B, subunits. Thus, a CLZ-defective A subunit no longer forms predominantly A/B heteromeric channels with the B subunit. A mechanism for this specificity involving the trimerization of the CLZ domain is proposed.
Phosphatidylinositol 4-kinase serves as a metabolic sensor and regulates priming of secretory granules in pancreatic β cells
Authors: Olsen Hervør L. , Høy Marianne , Zhang Wei , Bertorello Alejandro M. , Bokvist Krister , Capito Kirsten , Efanov Alexander M. , Meister Björn , Thams Peter , Yang Shao-Nian , Rorsman Patrik , Berggren Per-Olof , Gromada Jesper
Published: April 2003

Insulin secretion is controlled by the β cell′s metabolic state, and the ability of the secretory granules to undergo exocytosis increases during glucose stimulation in a membrane potential-independent fashion. Here, we demonstrate that exocytosis of insulin-containing secretory granules depends on phosphatidylinositol 4-kinase (PI 4-kinase) activity and that inhibition of this enzyme suppresses glucose-stimulated insulin secretion. Intracellular application of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P
2
] stimulated exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in a readily releasable pool. Reducing the cytoplasmic ADP concentration in a way mimicking the effects of glucose stimulation activated PI 4-kinase and increased exocytosis whereas changes of the ATP concentration in the physiological range had little effect. The PI(4,5)P
2
-binding protein Ca
2+
-dependent activator protein for secretion (CAPS) is present in β cells, and neutralization of the protein abolished both Ca
2+
- and PI(4,5)P
2
-induced exocytosis. We conclude that ADP-induced changes in PI 4-kinase activity, via generation of PI(4,5)P
2
, represents a metabolic sensor in the β cell by virtue of its capacity to regulate the release competence of the secretory granules.
Lessons from Kepler and the theory of everything
Authors: Wolfenstein Lincoln
Published: April 2003

Johannes Kepler's successes and failures provide lessons for reductionists seeking the theory of everything as well as for those who have proclaimed the end of reductionism.
Chemically programmed monoclonal antibodies for cancer therapy: Adaptor immunotherapy based on a covalent antibody catalyst
Authors: Rader Christoph , Sinha Subhash C. , Popkov Mikhail , Lerner Richard A. , Barbas Carlos F.
Published: April 2003

Proposing that a blend of the chemical diversity of small synthetic molecules with the immunological characteristics of the antibody molecule will lead to therapeutic agents with superior properties, we here present a device that equips small synthetic molecules with both effector function and long serum half-life of a generic antibody molecule. As a prototype, we developed a targeting device that is based on the formation of a covalent bond of defined stoichiometry between a 1,3-diketone derivative of an integrin α
v
β
3
and α
v
β
5
targeting Arg-Gly-Asp peptidomimetic and the reactive lysine of aldolase antibody 38C2. The resulting complex was shown to (
i
) spontaneously assemble
in vitro
and
in vivo
, (
ii
) selectively retarget antibody 38C2 to the surface of cells expressing integrins α
v
β
3
and α
v
β
5
, (
iii
) dramatically increase the circulatory half-life of the Arg-Gly-Asp peptidomimetic, and (
iv
) effectively reduce tumor growth in animal models of human Kaposi's sarcoma and colon cancer. This immunotherapeutic has the potential to target a variety of human cancers, acting on both the vasculature that supports tumor growth as well as the tumor cells themselves. Further, by use of a generic antibody molecule that forms a covalent bond with a 1,3-diketone functionality, essentially any compound can be turned into an immunotherapeutic agent thereby not only increasing the diversity space that can be accessed but also multiplying the therapeutic effect.
Involvement of β
3
-adrenergic receptor activation via cyclic GMP- but not NO-dependent mechanisms in human corpus cavernosum function
Authors: Cirino Giuseppe , Sorrentino Raffaella , di Villa Bianca Roberta d'Emmanuele , Popolo Ada , Palmieri Alessandro , Imbimbo Ciro , Fusco Ferdinando , Longo Nicola , Tajana Gianfranco , Ignarro Louis J. , Mirone Vincenzo
Published: April 2003

The β
3
-adrenoreceptor plays a major role in lipolysis but the role and distribution of β
3
-receptors in other specific sites have not been extensively studied. β
3
-adrenergic receptors are present not only in adipose tissue but also in human gall bladder, colon, prostate, and skeletal muscle. Recently, β
3
-adrenergic receptor stimulation was shown to elicit vasorelaxation of rat aorta through the NO–cGMP signal transduction pathway. Here we show that β
3
-receptors are present in human corpus cavernosum and are localized mainly in smooth muscle cells. After activation by a selective β
3
-adrenergic receptor agonist, BRL 37344, there was a cGMP-dependent but NO-independent vasorelaxation that was selectively blocked by a specific β
3
-receptor antagonist. In addition, we report that the human corpus cavernosum exhibits basal β
3
-receptor-mediated vasorelaxant tone and that β
3
-receptor activity is linked to inhibition of the RhoA/Rho-kinase pathway. These observations indicate that β
3
-receptors may play a physiological role in mediating penile erection and, therefore, could represent a therapeutic target for treatment of erectile dysfunction.
Naturalizing consciousness: A theoretical framework
Authors: Edelman Gerald M.
Published: April 2003

Consciousness has a number of apparently disparate properties, some of which seem to be highly complex and even inaccessible to outside observation. To place these properties within a biological framework requires a theory based on a set of evolutionary and developmental principles. This paper describes such a theory, which aims to provide a unifying account of conscious phenomena.
Complete genome sequence of the Q-fever pathogenCoxiellaburnetii
Authors: Seshadri Rekha , Paulsen Ian T. , Eisen Jonathan A. , Read Timothy D. , Nelson Karen E. , Nelson William C. , Ward Naomi L. , Tettelin Hervé , Davidsen Tanja M. , Beanan Maureen J. , Deboy Robert T. , Daugherty Sean C. , Brinkac Lauren M. , Madupu Ramana , Dodson Robert J. , Khouri Hoda M. , Lee Kathy H. , Carty Heather A. , Scanlan David , Heinzen Robert A. , Thompson Herbert A. , Samuel James E. , Fraser Claire M. , Heidelberg John F.
Published: April 2003

The 1,995,275-bp genome ofCoxiella burnetii, Nine Mile phase I RSA493, a highly virulent zoonotic pathogen and category B bioterrorism agent, was sequenced by the random shotgun method. This bacterium is an obligate intracellular acidophile that is highly adapted for life within the eukaryotic phagolysosome. Genome analysis revealed many genes with potential roles in adhesion, invasion, intracellular trafficking, host-cell modulation, and detoxification. A previously uncharacterized 13-member family of ankyrin repeat-containing proteins is implicated in the pathogenesis of this organism. Although the lifestyle and parasitic strategies ofC. burnetiiresemble that ofRickettsiaeandChlamydiae, their genome architectures differ considerably in terms of presence of mobile elements, extent of genome reduction, metabolic capabilities, and transporter profiles. The presence of 83 pseudogenes displays an ongoing process of gene degradation. Unlike other obligate intracellular bacteria, 32 insertion sequences are found dispersed in the chromosome, indicating some plasticity in theC. burnetiigenome. These analyses suggest that the obligate intracellular lifestyle ofC. burnetiimay be a relatively recent innovation.
A defined protein–detergent–lipid complex for crystallization of integral membrane proteins: The cytochrome
b
6
f
complex of oxygenic photosynthesis
Authors: Zhang Huamin , Kurisu Genji , Smith Janet L. , Cramer William A.
Published: April 2003

The paucity of integral membrane protein structures creates a major bioinformatics gap, whose origin is the difficulty of crystallizing these detergent-solubilized proteins. The problem is particularly formidable for hetero-oligomeric integral membrane proteins, where crystallization is impeded by the heterogeneity and instability of the protein subunits and the small lateral pressure imposed by the detergent micelle envelope that surrounds the hydrophobic domain. In studies of the hetero (eight subunit)-dimeric 220,000 molecular weight cytochrome

b
6
f

complex, derived from the thermophilic cyanobacterium,
Mastigocladus laminosus
, crystals of the complex in an intact state could not be obtained from highly purified delipidated complex despite exhaustive screening. Crystals of proteolyzed complex could be obtained that grew very slowly and diffracted poorly. Addition to the purified lipid-depleted complex of a small amount of synthetic nonnative lipid, dioleolyl-phosphatidylcholine, resulted in a dramatic improvement in crystallization efficiency. Large crystals of the intact complex grew overnight, whose diffraction parameters are as follows: 94% complete at 3.40 Å spacing;
R
merge
= 8.8% (38.5%), space group,
P
6
1
22; and unit cell parameters,
a
=
b
= 156.3 Å,
c
= 364.0 Å, α = β = 90
o
, γ = 120
o
. It is proposed that the methodology of augmentation of a well-defined lipid-depleted integral membrane protein complex with synthetic nonnative lipid, which can provide conformational stability to the protein complex, may be of general use in the crystallization of integral membrane proteins.
Group B streptococcal phospholipid causes pulmonary hypertension
Authors: Curtis Jerri , Kim Geumsoo , Wehr Nancy B. , Levine Rodney L.
Published: April 2003

Group B
Streptococcus
is the most common cause of bacterial infection in the newborn. Infection in many cases causes persistent pulmonary hypertension, which impairs gas exchange in the lung. We purified the bacterial components causing pulmonary hypertension and identified them as cardiolipin and phosphatidylglycerol. Synthetic cardiolipin or phosphatidylglycerol also induced pulmonary hypertension in lambs. The recognition that bacterial phospholipids may cause pulmonary hypertension in newborns with Group B streptococcal infection opens new avenues for therapeutic intervention.
Neural mechanisms of empathy in humans: A relay from neural systems for imitation to limbic areas
Authors: Carr Laurie , Iacoboni Marco , Dubeau Marie-Charlotte , Mazziotta John C. , Lenzi Gian Luigi
Published: April 2003

How do we empathize with others? A mechanism according to which action representation modulates emotional activity may provide an essential functional architecture for empathy. The superior temporal and inferior frontal cortices are critical areas for action representation and are connected to the limbic system via the insula. Thus, the insula may be a critical relay from action representation to emotion. We used functional MRI while subjects were either imitating or simply observing emotional facial expressions. Imitation and observation of emotions activated a largely similar network of brain areas. Within this network, there was greater activity during imitation, compared with observation of emotions, in premotor areas including the inferior frontal cortex, as well as in the superior temporal cortex, insula, and amygdala. We understand what others feel by a mechanism of action representation that allows empathy and modulates our emotional content. The insula plays a fundamental role in this mechanism.
Acidic pH induces topoisomerase II-mediated DNA damage
Authors: Xiao Hai , Li Tsai-Kun , Yang Jin-Ming , Liu Leroy F.
Published: April 2003

Acidic pH plays an important role in various pathophysiological states and has been demonstrated to be carcinogenic in animal models. Recent studies have also implicated acidic pH in the development of preneoplastic Barrett's esophagus in human. However, little is known about the molecular mechanism underlying acidic pH-induced carcinogenesis. In the current study, we show that acidic pH, like the topoisomerase II (TOP2) poison VP-16 (demethylepipodophyllotoxin ethylidene-β-
d
-glucoside), induces tumors in 9,10-dimethyl-1,2-benzanthracene(DMBA)-initiated mice. The following studies in tissue culture models have suggested that acidic pH acts like a TOP2 poison to induce TOP2-mediated DNA damage: (
i
) acidic pH induces TOP2-dependent DNA damage signals as evidenced by up-regulation of p53 and Ser-139 phosphorylation of H2AX [a substrate for ataxia telangiectasia mutated (ATM)/ATM and Rad3-related (ATR) kinases]; (
ii
) acidic pH-induced cytotoxicity in tumor cells is reduced in TOP2-deficient cells; (
iii
) acidic pH increases the mutation frequency of the hypoxanthine phosphoribosyl transferase (HPRT) gene in a TOP2-dependent manner; and (
iv
) acidic pH induces reversible TOP2-mediated DNA strand breaks
in vitro
. We discuss the possibility that TOP2-mediated DNA damage may contribute to acidic pH-induced carcinogenesis.
Autoreactive T cells can be protected from tolerance induction through competition by flanking determinants for access to class II MHC
Authors: Maverakis Emanual , Beech Jonathan , Stevens David B. , Ametani Akio , Brossay Laurent , van den Elzen Peter , Mendoza Richard , Thai Quoc , Macias Luis H. , Ethell Doug , Campagnoni Celia W. , Campagnoni Anthony T. , Sette Alessandro , Sercarz Eli E.
Published: April 2003

It is not clear why the N-terminal autoantigenic determinant of myelin basic protein (MBP), Ac1–9, is dominant in the B1O.PL (H-2u) mouse, given its weak I-Au-MHC binding affinity. Similarly, how do high-affinity T cells specific for this determinant avoid negative selection? Because the MBP:1–9 sequence is embryonically expressed uniquely in the context of Golli-MBP, determinants were sought within the contiguous N-terminal “Golli” region that could out-compete MBP:1–9 for MHC binding, and thereby prevent negative selection of the public response to Ac1–9, shown here to be comprised of a Vβ8.2Jβ2.7 and a Vβ8.2Jβ2.4 expansion. Specifically, we demonstrate that Ac1–9 itself can be an effective inducer of central tolerance induction; however, in the context of Golli-MBP, Ac1–9 is flanked by determinants which prevent its display to autoreactive T cells. Our data support competitive capture as a means of protecting high-affinity, autoreactive T cells from central tolerance induction.
Glucagon-like peptide 1 (1–37) converts intestinal epithelial cells into insulin-producing cells
Authors: Suzuki Atsushi , Nakauchi Hiromitsu , Taniguchi Hideki
Published: April 2003

Glucagon-like peptide (GLP) 1 is produced through posttranslational processing of proglucagon and acts as a regulator of various homeostatic events. Among its analogs, however, the function of GLP-1-(1–37), synthesized in small amounts in the pancreas, has been unclear. Here, we find that GLP-1-(1–37) induces insulin production in developing and, to a lesser extent, adult intestinal epithelial cells
in vitro
and
in vivo
, a process mediated by up-regulation of the Notch-related gene
ngn3
and its downstream targets, which are involved in pancreatic endocrine differentiation. These cells became responsive to glucose challenge
in vitro
and reverse insulin-dependent diabetes after implantation into diabetic mice. Our findings suggest that efficient induction of insulin production in intestinal epithelial cells by GLP-1-(1–37) could represent a new therapeutic approach to diabetes mellitus.
Observation of the cascaded atomic-to-global length scales driving protein motion
Authors: Armstrong M. R. , Ogilvie J. P. , Cowan M. L. , Nagy A. M. , Miller R. J. D.
Published: April 2003

Model studies of the ligand photodissociation process of carboxymyoglobin have been conducted by using amplified few-cycle laser pulses short enough in duration (<10 fs) to capture the phase of the induced nuclear motions. The reaction-driven modes are observed directly in real time and depict the pathway by which energy liberated in the localized reaction site is efficiently channeled to functionally relevant mesoscale motions of the protein.
Crystal structure of human junctional adhesion molecule 1: Implications for reovirus binding
Authors: Prota Andrea E. , Campbell Jacquelyn A. , Schelling Pierre , Forrest J. Craig , Watson Melissa J. , Peters Timothy R. , Aurrand-Lions Michel , Imhof Beat A. , Dermody Terence S. , Stehle Thilo
Published: April 2003

Reovirus attachment to cells is mediated by the binding of viral attachment protein σ1 to junctional adhesion molecule 1 (JAM1). The crystal structure of the extracellular region of human JAM1 (hJAM1) reveals two concatenated Ig-type domains with a pronounced bend at the domain interface. Two hJAM1 molecules form a dimer that is stabilized by extensive ionic and hydrophobic contacts between the N-terminal domains. This dimeric arrangement is similar to that observed previously in the murine homolog of JAM1, indicating physiologic relevance. However, differences in the dimeric structures of hJAM1 and murine JAM1 suggest that the interface is dynamic, perhaps as a result of its ionic nature. We demonstrate that hJAM1, but not the related proteins hJAM2 and hJAM3, serves as a reovirus receptor, which provides insight into sites in hJAM1 that likely interact with σ1. In addition, we present evidence that the previously reported structural homology between σ1 and the adenovirus attachment protein, fiber, also extends to their respective receptors, which form similar dimeric structures. Because both receptors are located at regions of cell–cell contact, this similarity suggests that reovirus and adenovirus use conserved mechanisms of entry and pathways of infection.
Modulation of p47

PHOX

activity by site-specific phosphorylation: Akt-dependent activation of the NADPH oxidase
Authors: Hoyal Carolyn R. , Gutierrez Abel , Young Brandon M. , Catz Sergio D. , Lin Jun-Hsiang , Tsichlis Philip N. , Babior Bernard M.
Published: April 2003

The leukocyte NADPH oxidase catalyzes the reduction of oxygen to O

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at the expense of NADPH. Extensive phosphorylation of the oxidase subunit p47

PHOX

occurs during the activation of the enzyme in intact cells. p47

PHOX

carrying certain serine-to-alanine mutations fails to support NADPH oxidase activity in intact cells, suggesting that the phosphorylation of specific serines on p47

PHOX

is required for the activation of the oxidase. Earlier studies with both intact cells and a kinase-dependent, cell-free system have suggested that protein kinase C can phosphorylate those serines of p47

PHOX

whose phosphorylation is necessary for its activity. Work with inhibitors suggested that a phosphatidylinositol 3-kinase-dependent pathway also can activate the oxidase. Phosphorylation of p47

PHOX

by Akt (protein kinase B), whose activation depends on phosphatidylinositol 3-kinase, could be the final step in such a pathway. We now find that Akt activates the oxidase
in vitro
by phosphorylating serines S304 and S328 of p47

PHOX

. These results suggest that Akt could participate in the activation of the leukocyte NADPH oxidase.
A reelin–integrin receptor interaction regulates Arc mRNA translation in synaptoneurosomes
Authors: Dong Erbo , Caruncho Hector , Liu Wen Sheng , Smalheiser Neil R. , Grayson Dennis R. , Costa Erminio , Guidotti Alessandro
Published: April 2003

Reelin is synthesized and secreted into extracellular matrix by cortical γ-aminobutyric acid (GABA)ergic interneurons and binds with high affinity to the extracellular domain of integrin receptors expressed in dendritic shaft and spine postsynaptic densities (DSPSD) of pyramidal neurons. In heterozygous reeler mice, reelin bound to DSPSD, and the expression of Arc (activity-regulated cytoskeletal protein) is lower than in wild-type mice. We studied the effect of reelin on Arc and total protein synthesis in synaptoneurosomes (SNSs) prepared from mouse neocortex. Recombinant full-length mouse reelin displaces the high affinity (
K
D
= 60 fM) binding of [
125
I]echistatin (a competitive integrin receptor antagonist) to integrin receptors with a
K
i
of 22 pM and with a Hill slope close to 1. Echistatin (50–100 nM) competitively antagonizes and abates reelin binding. The addition of reelin (2–40 pM) to SNSs enhances the incorporation of [
35
S]methionine into Arc and other rapidly translated proteins in a concentration-dependent manner. This incorporation is virtually abolished by 50–100 nM echistatin or by 5–10 nM rapamycin, a blocker of the
mammalian target of rapamycin
kinase. We conclude that reelin binds with high affinity to integrin receptors expressed in SNSs and thereby activates Arc protein synthesis.
Comparison of high-field-side and low-field-side launch ECCD in the W7-AS stellarator
Authors: M Romé  , V Erckmann  , H P Laqua  , H Maaßberg  , N B Marushchenko
Published: April 2003

The electron cyclotron current drive (ECCD) with extraordinary mode at the second cyclotron harmonic launched from the high-field-side (HFS) is investigated in W7-AS stellarator. Trapped particle effects and quasi-linear effects are taken into account in linear ray-tracing and quasi-linear bounce-averaged Fokker–Planck computations of the driven current. The results for both low-field-side (LFS) and HFS injection in W7-AS are compared with the experimental results. A slightly lower current drive efficiency is obtained, both theoretically and experimentally, in the case of HFS injection, confirming the LFS launch as the preferred mode of operation for ECCD.
Numerical solutions of a viscous‐hydrodynamic model for semiconductors: the supersonic case
Authors: Ballestra Luca , Saleri Fausto
Published: April 2003

In this paper, we solve by a finite difference upwinded method an extended hydrodynamic model for semiconductors, with viscous terms in the momentum equation. In particular, we consider the simulation of a one‐dimensional n+‐n ‐n+ diode, whose solution exhibits at low temperatures strong discontinuities, and investigate the effect of the momentum viscosity on the shock waves. Numerical experiments, performed also on a two‐dimensional test case, demonstrate that the numerical scheme, working on non‐uniform grids, is suitable to describe solutions with strong variations in time and space. Well‐posedness for the boundary conditions is discussed, and a linear stability estimate is established for the one‐dimensional n+‐n ‐n+ diode benchmark problem.
Fixed‐point technique in computing nonlinear eddy current problems
Authors: Peterson Wieslaw
Published: April 2003

Eddy currents are investigated in a ferromagnetic bar exposed to a transverse magnetic field. Such an open boundary field problem is analysed applying the Galerkin finite element method coupled with a separation of variables. A steady state is considered, introducing time periodic conditions. The resultant system of nonlinear equations is solved using an iterative procedure based on Brouwer's fixed‐point theorem referred to the nonlinear material reluctivity. Numerical results are presented for a massive conductor made of cast steel and cast iron. The eddy‐current distribution and characteristics of power losses are illustrated in a graphic form.
Modelling and simulation with neural and fuzzy‐neural networks of switched circuits
Authors: Demir Yakup , Uçar Ayşegül
Published: April 2003

Recently, the modelling and simulation of switched systems containing new nonlinear components in electronics and power electronics industry have gained importance. In this paper, both feed‐forward artificial neural networks (ANN) and adaptive network‐based fuzzy inference systems (ANFIS) have been applied to switched circuits and systems. Then their performances have been compared in this contribution by developed simulation programs. It has been shown that ANFIS require less training time and offer better performance than those of ANN. In addition, ANFIS using “clustering algorithm” to generate the rules and the numbers of membership functions gives a smaller number of parameters, better performance and less training time than those of ANFIS using “grid partition” to generate the rules. The work not only demonstrates the advantage of the ANFIS architecture using clustering algorithm but also highlights the advantages of the architecture for hardware realizations.
Fourier analysis of hysteretic distortions
Authors: Takács Jenö
Published: April 2003

The paper presents the derivation of the Fourier coefficients of the magnetisation wave form in closed form for periodic triangular field excitation. The mathematical model used here to approximate the hysteresis loop applies exponential functions and it is presented briefly in the first part of the paper. This method of calculation is applicable to a group of excitation wave forms, constructed of straight lines, such as square, triangular and trapezoid wave forms. The criteria for the Rayleigh region is given and an appropriate formulation of the Fourier coefficients in closed form for the Rayleigh region is also described. It is shown that the calculation is also applicable to anhysteretic processes both in the saturation and in the “small” signal (Rayleigh) region. The Fourier components of the periodic magnetisation wave form resulting from an anhysteretic magnetisation process are also calculated in closed form for triangular field excitation.
Electromechanical properties of a disc‐type salient‐pole brushless DC motor with different pole numbers
Authors: Lukaniszyn Marian , Jagiela Mariusz , Wrobel Rafal
Published: April 2003

A brushless, permanent magnet, three‐phase disc‐type salient‐pole DC motor with co‐axial flux in the stator is considered. Electromechanical properties of a basic eight‐pole motor are compared with those for a 16‐pole one of the same volume, in order to contrast the two potential candidates for variable‐speed, low‐cost drives. As a basis of the comparative analysis, 3D FEM magnetic field modelling and circuit analysis considering an electronic commutator are employed. Increasing the number of poles results in unfavourable raising in the switching frequency. The eight‐pole motor construction has been shown in simulations to have higher efficiency and lower power losses than its 16‐pole counterpart.
Use and analysis of null flux coils
Authors: Davey Kent R.
Published: April 2003

There are a number of ways to maintain stable levitation and guidance in Maglev through induction. If the secondary currents are unconstrained, the lift to drag ratio is much less than that realizable with constrained currents in a null flux configuration, regardless of whether the source field is superconducting. This paper investigates 2D and 3D boundary element formulations capable of computing forces on such systems. Such systems pose a special challenge because they involve cross‐connected coils having complete flux cancellation when the system is centered. Both 2D and 3D examples are compared to data on a circular test rig.
Stochastic response surface method and tolerance analysis in microelectronics
Authors: Marcello Anile Angelo , Spinella Salvatore , Rinaudo Salvatore
Published: April 2003

Tolerance analysis is a very important tool for chip design in the microelectronics industry. The usual method for tolerance analysis is Monte Carlo simulation, which, however, is extremely CPU intensive, because in order to yield statistically significant results, it needs to generate a large sample of function values. Here we report on another method, recently introduced in several fields, called stochastic response surface method, which might be a viable alternative to Monte Carlo simulation for some classes of problems. The application considered here is on the tolerance analysis of the current of a submicrometer n+‐n‐n+ diode as a function of the channel length and the channel doping. The numerical simulator for calculating the current is based on the energy transport hydrodynamical model introduced by Stratton, which is one of the most widely used in this field.
New approach to the optimisation of three‐phase three‐wire systems with sinusoidal voltage sources and nonlinear loads
Authors: Marian Pasko , Krzysztof Debowski
Published: April 2003

The problems presented in the paper deal with the three‐phase three‐wire system with sinusoidal voltage sources and nonlinear loads. In the model of the three‐phase voltage source the inner impedance has been included. In contrast to earlier proposed methods, the solution of this problem is based in the frequency domain. This method can be used for systems with some classes of nonlinear loads, i.e. for inertialess elements, which consume the active power of the basic harmonic of the voltage source and where the currents of the system are periodic. The above‐mentioned power is an additional condition of the presented minimisation. The solution (the active currents) is obtained by means of Lagrange factors and a suitable measurement experiment. The last stage of this method is the determination of the parameters of the compensator, which connected to the system under research evoke the active currents of the voltage sources. This working point for the three‐phase three‐wire system can be obtained by means of LC, RLC or (RLC,‐R) compensators.
Probabilistic approach to series compensation design
Authors: Allella Flavio , Chiodo Elio , Lauria Davide
Published: April 2003

Series capacitive compensation in electrical power systems is generally recognized as a very economical and powerful means for increasing the transmission capability of long‐distance transmission lines, resulting in relevant technical advantages in power system behavior: increased steady‐state and transient stability margins, reduced voltage drop in receiving systems during occurrence of severe contingencies and reduction of transmission losses. In this paper, a general method for choosing the series compensation degree is proposed, focusing the attention on the transient stability aspect. The approach, based upon a probabilistic framework, allows to properly select – at the design stage – the optimal degree of series compensation in order to contain the instability risk at an acceptable value. The transient stability problem is formulated by using the transient energy function method. In order to show the feasibility of the proposed approach, a numerical application to the Cigre test network is performed in the final part of the paper.
Category, slot harmonics and the torque of induction machines
Authors: Rusek Jan
Published: April 2003

Based on Fourier series theory, for almost periodic functions, the general as well as the specific harmonic‐balance model of induction machines is presented together with a brief derivation. Whereas the general model refers to both symmetrical and asymmetrical machines, the specific one is valid for only the former ones, with windings without parallel branches. The specific model permits classification of all symmetrical machines into three categories. The classification preserves its usefulness for machines not strictly fulfilling assumptions for the validity of the specific model. Expressions for the asynchronous and synchronous torque components are derived. Categories as well as frequencies of both the slot harmonics and the synchronous torques are listed in four tables referring to machines with one to four pole pairs.
Simulations of bilateral energy markets using MATLAB
Authors: Yuen Y.S.C. , Lo K.L.
Published: April 2003

This paper presents simulation results of energy bilateral markets using MATLAB/SIMULINK. The algorithm for congestion management and transmission pricing is implemented by means of DC load flow. The simulation results show how elasticity of market participants to transmission usage charges can affect the overall network usage and its cost.
Stimulation of L‐type Ca2+ Channels by Inositol Pentakis‐ and Hexakisphosphates in Rat Vascular Smooth Muscle Cells
Authors: Quignard J. F. , Rakotoarisoa L. , Mironneau J. , Mironneau C.
Published: April 2003

The electrophysiological effects of d‐myo‐inositol 1,3,4,5,6‐pentakisphosphate (InsP5) and d‐myo‐inositol hexakisphosphate (InsP6), which represent the main cellular inositol polyphosphates, were studied on L‐type Ca2+ channels in single myocytes of rat portal vein. Intracellular infusion of InsP5 (up to 50 μm) or 10 μm InsP6 had no action on Ba2+ current, whereas 50 μm InsP6 or 10 μm InsP5 plus 10 μm InsP6 (InsP5,6) stimulated the inward current. The stimulatory effect of InsP5,6 was also obtained in external Ca2+‐containing solution. The stimulated Ba2+ current retained the properties of L‐type Ba2+ current and was oxodipine sensitive. PKC inhibitors Ro 32‐0432 (up to 500 nm), GF109203X (5 μm) or calphostin C (100 nm) abolished the InsP5,6‐induced stimulation. Neither the PKA inhibitor H89 (1 μm) nor the protein phosphatase inhibitors okadaic acid (500 nm) or cypermethrin (1 μm) prevented or mimicked the InsP5,6‐induced stimulation of Ba2+ current. However, InsP5 or InsP6 could mimic some effects of protein phosphatase inhibitor so as to extend after washing‐out forskolin the stimulatory effects of the adenylyl cyclase activator on Ba2+ current. These results indicate that InsP5 and InsP6 may act as intracellular messengers in modulating L‐type Ca2+ channel activity and so could be implicated in mediator‐induced contractions of vascular smooth muscle cells.
A Reappraisal of the Blood Glucose Homeostat which Comprehensively Explains the Type 2 Diabetes Mellitus–Syndrome X Complex
Authors: Koeslag Johan H. , Saunders Peter T. , Terblanche Elmarie
Published: April 2003

Blood glucose concentrations are unaffected by exercise despite very high rates of glucose flux. The plasma ionised calcium levels are even more tightly controlled after meals and during lactation. This implies ‘integral control’. However, pairs of integral counterregulatory controllers (e.g. insulin and glucagon, or calcitonin and parathyroid hormone) cannot operate on the same controlled variable, unless there is some form of mutual inhibition. Flip‐flop functional coupling between pancreatic α‐ and β‐cells via gap junctions may provide such a mechanism. Secretion of a common inhibitory chromogranin by the parathyroids and the thyroidal C‐cells provides another. Here we describe how the insulin:glucagon flip‐flop controller can be complemented by growth hormone, despite both being integral controllers. Homeostatic conflict is prevented by somatostatin‐28 secretion from both the hypothalamus and the pancreatic islets. Our synthesis of the information pertaining to the glucose homeostat that has accumulated in the literature predicts that disruption of the flip‐flop mechanism by the accumulation of amyloid in the pancreatic islets in type 2 diabetes mellitus will lead to hyperglucagonaemia, hyperinsulinaemia, insulin resistance, glucose intolerance and impaired insulin responsiveness to elevated blood glucose levels. It explains syndrome X (or metabolic syndrome) as incipient type 2 diabetes in which the glucose control system, while impaired, can still maintain blood glucose at the desired level. It also explains why it is characterised by high plasma insulin levels and low plasma growth hormone levels, despite normoglycaemia, and how this leads to central obesity, dyslipidaemia and cardiovascular disease in both syndrome X and type 2 diabetes.
Re‐Evaluation of Muscle Wisdom in the Human Adductor Pollicis using Physiological Rates of Stimulation
Authors: Fuglevand Andrew J. , Keen Douglas A.
Published: April 2003

Motor unit discharge rates decline by about 50 % over 60 s of a sustained maximum voluntary contraction (MVC). It has been suggested that this decline in discharge rate serves to maintain force by protecting against conduction failure and by optimizing the input to motor units as their contractile properties change. This hypothesis, known as muscle wisdom, is based in part on studies in which muscle force was shown to decline more rapidly when stimulation was maintained at a high rate than when stimulus rate was reduced over time. The stimulus rates used in those studies, however, were higher than those normally encountered during MVCs. The purpose of this study was to compare force loss under constant and declining stimulus rate conditions using rates similar to those that occur during voluntary effort. Isometric force and surface EMG signals were recorded from human adductor pollicis muscles in response to supramaximal stimuli delivered to the ulnar nerve at the elbow. Three fatigue protocols, each 60 s in duration, were carried out on separate days on each of 10 subjects: (1) continuous stimulation at 30 Hz, (2) stimulation at progressively decreasing rates from 30 to 15 Hz and (3) sustained MVC. The relative force–time integral (endurance index) was significantly smaller for the sustained MVC (0.75 ± 0.08) and decreasing stimulus rate conditions (0.76 ± 0.16) compared to the condition in which stimulus rate was maintained at 30 Hz (0.90 ± 0.13). These findings suggest that decreases in discharge rate may contribute to force decline during a sustained MVC.