bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversal of anticancer multidrug resistance by the ardeemins
Authors: Chou Ting-Chao , Depew Kristopher M. , Zheng Yu-Huang , Safer Michelle L. , Chan Daniel , Helfrich Barbara , Zatorska Danuta , Zatorski Andrzej , Bornmann William , Danishefsky Samuel J.
Published: July 2002

Two “reverse prenyl” hexahydropyrroloindole alkaloids, 5-
N
-acetylardeemin and 5-
N
-acetyl-8-demethylardeemin, were evaluated as reversal agents in cells exhibiting a multidrug resistant (MDR) phenotype. These ardeemins (
i
) reversed drug resistance to vinblastine (VBL) or to taxol as much as 700-fold at relatively noncytotoxic concentrations
in vitro
; (
ii
) as a single agent at high concentrations killed MDR cells more efficaciously than the respective parent wild-type cells; and (
iii
) exhibited strong synergistic effects with doxorubicin (DX) and VBL against the growth of MDR neoplastic cells, and to a lesser extent, of the parent wild-type cells. Mechanistic studies showed that photoaffinity labeling of P-glycoprotein (Pgp) with [
3
H] azidopine was competitively inhibited by the ardeemins. Resistance to DX in MDR-[Pgp
+
and MDR-associated protein (MRP)
+
], MDR-Pgp
+
, lung resistance protein (LRP)
+
-expressing, and wild-type lung cancer cells were reversed 110- to 200-fold, 50- to 66-fold, 7- to 15-fold, and 0.9- to 3-fold, respectively, by 20 μM of the ardeemins. Moreover, these compounds increased the intracellular accumulation of VBL and markedly decreased its efflux. Finally,
in vivo
combination studies demonstrated that nontoxic doses of the ardeemins with DX significantly improved the chemotherapeutic effects in B6D2F
1
mice bearing DX-resistant P388 leukemia, and nude mice bearing human MX-1 mammary carcinoma xenografts. The above features indicate that the ardeemins may have utility in the therapy of cancer.
Conditional lineage ablation to model human diseases
Authors: Lee Paul , Morley Gregory , Huang Qian , Fischer Avi , Seiler Stephanie , Horner James W. , Factor Stephen , Vaidya Dhananjay , Jalife José , Fishman Glenn I.
Published: July 2002

Cell loss contributes to the pathogenesis of many inherited and acquired human diseases. We have developed a system to conditionally ablate cells of any lineage and developmental stage in the mouse by regulated expression of the diphtheria toxin A (DTA) gene by using tetracycline-responsive promoters. As an example of this approach, we targeted expression of DTA to the hearts of adult mice to model structural abnormalities commonly observed in human cardiomyopathies. Induction of DTA expression resulted in cell loss, fibrosis, and chamber dilatation. As in many human cardiomyopathies, transgenic mice developed spontaneous arrhythmias
in vivo
, and programmed electrical stimulation of isolated-perfused transgenic hearts demonstrated a strikingly high incidence of spontaneous and inducible ventricular tachycardia. Affected mice showed marked perturbations of cardiac gap junction channel expression and localization, including a subset with disorganized epicardial activation patterns as revealed by optical action potential mapping. These studies provide important insights into mechanisms of arrhythmogenesis and suggest that conditional lineage ablation may have wide applicability for studies of disease pathogenesis.
Slow rate of molecular evolution in high-elevation hummingbirds
Authors: Bleiweiss Robert
Published: July 2002

Estimates of relative rates of molecular evolution from a DNA-hybridization phylogeny for 26 hummingbird species provide evidence for a negative association between elevation and rate of single-copy genome evolution. This effect of elevation on rate remains significant even after taking into account a significant negative association between body mass and molecular rate. Population-level processes do not appear to account for these patterns because (i) all hummingbirds breed within their first year and (ii) the more extensive subdivision and speciation of bird populations living at high elevations predicts a positive association between elevation and rate. The negative association between body mass and molecular rate in other organisms has been attributed to higher mutation rates in forms with higher oxidative metabolism. As ambient oxygen tensions and temperature decrease with elevation, the slow rate of molecular evolution in high-elevation hummingbirds also may have a metabolic basis. A slower rate of single-copy DNA change at higher elevations suggests that the dynamics of molecular evolution cannot be separated from the environmental context.
Inability of keratinocytes lacking their specific transglutaminase to form cross-linked envelopes: Absence of envelopes as a simple diagnostic test for lamellar ichthyosis
Authors: Jeon Saewha , Djian Philippe , Green Howard
Published: July 2002

Epidermal keratinocytes, late in their terminal differentiation, form cross-linked envelopes resistant to ionic detergent and reducing agent. Because the cross-linking process is catalyzed by the keratinocyte transglutaminase, the absence of active transglutaminase should result in failure of the keratinocyte to form a cross-linked envelope. Three keratinocyte strains bearing mutations in the keratinocyte transglutaminase were examined: two contained no detectable transglutaminase mRNA and none contained active enzyme. All three were unable to form cross-linked envelopes, either spontaneously in stratified cultures or upon induction with Ca
2+
. Although stratum corneum of normal humans and scales from patients with different ichthyotic diseases contain cross-linked envelopes, those from patients with transglutaminase-negative lamellar ichthyosis do not. Therefore, the disease due to the absence of transglutaminase may be readily distinguished from other ichthyotic diseases by a simple test for cross-linked envelopes.
A transcriptional activating region with two contrasting modes of protein interaction
Authors: Ansari Aseem Z. , Reece Richard J. , Ptashne Mark
Published: July 2002

A C-terminal segment of the yeast activator Gal4 manifests two functions: When tethered to DNA, it elicits gene activation, and it binds the inhibitor Gal80. Here we examine the effects on these two functions of cysteine and proline substitutions. We find that, although certain cysteine substitutions diminish interaction with Gal80, those substitutions have little effect on the activating function
in vivo
and interaction with TATA box-binding protein (TBP)
in vitro
. Proline substitutions introduced near residues critical for Gal80 binding abolish that interaction but once again have no effect on the activating function. Crosslinking experiments show that a defined position in the activating peptide is in close proximity to TBP and Gal80 in the two separate reactions and show that binding of the inhibitor blocks binding to TBP. Thus, the same stretch of amino acids are involved in two quite different protein–protein interactions: binding to Gal80, which depends on a precise sequence and the formation of a defined secondary structure, or interactions with the transcriptional machinery
in vivo
, which are not impaired by perturbations of either sequence or structure.
Identity of adenylyl cyclase isoform determines the rate of cell cycle progression in NIH 3T3 cells
Authors: Smit Martine J. , Verzijl Dennis , Iyengar Ravi
Published: July 2002

Cell cycle progression is regulated by cAMP in several cell types. Cellular cAMP levels depend on the activity of different adenylyl cyclases (ACs), which have varied signal-receiving capabilities. The role of individual ACs in regulating proliferative responses was investigated. Native NIH 3T3 cells contain AC6, an isoform that is inhibited by a variety of signals. Proliferation of exogenous AC6-expressing cells was the same as in control cells. In contrast, expression of AC2, an isoform stimulated by protein kinase C (PKC), resulted in inhibition of cell cycle progression and increased doubling time. In AC2-expressing cells, platelet-derived growth factor (PDGF) elevated cAMP levels in a PKC-dependent manner. PDGF stimulation of mitogen-activated protein kinases 1 and 2 (MAPK 1,2), DNA synthesis, and cyclin D1 expression was reduced in AC2-expressing cells as compared with control cells. Dominant negative protein kinase A relieved the AC2 inhibition of PDGF-induced DNA synthesis. Expression of AC2 also blocked H-ras-induced transformation of NIH 3T3 cells. These observations indicate that, because AC2 is stimulated by PKC, it can be activated by PDGF concurrently with the stimulation of MAPK 1,2. The elevation in cAMP results in inhibition of signal flow from the PDGF receptor to MAPK 1,2 and a significant reduction in the proliferative response to PDGF. Thus, the molecular identity and signal receiving capability of the AC isoforms in a cell could be important for proliferative homeostasis.
Defective stratum corneum and early neonatal death in mice lacking the gene for transglutaminase 1 (keratinocyte transglutaminase)
Authors: Matsuki Masato , Yamashita Fumiyoshi , Ishida-Yamamoto Akemi , Yamada Keiko , Kinoshita Chikako , Fushiki Shinji , Ueda Eiichiro , Morishima Yohichi , Tabata Kohichi , Yasuno Hirokazu , Hashida Mitsuru , Iizuka Hajime , Ikawa Masahito , Okabe Masaru , Kondoh Gen , Kinoshita Taroh , Takeda Junji , Yamanishi Kiyofumi
Published: July 2002

The stratum corneum of the skin serves as an effective barrier for maintenance of the internal milieu against the external environment. At the cell periphery of the stratum corneum is the cell envelope, a highly insoluble membranous structure composed of precursor proteins cross-linked by ɛ-(γ-glutamyl)lysine bonds. Transglutaminase 1 (TGase 1; keratinocyte TGase), a membrane-bound isozyme of the TGase family, has been proposed to catalyze this process of assembly. Deficient cross-linking of the cell envelope in some patients with the autosomal recessive skin disorder lamellar ichthyosis (LI) and several mutations of the TGase 1 gene that have been identified in families with LI suggest the importance of this gene in production of the cell envelope. In this study, we generated mice lacking the TGase 1 gene, and we report that they have erythrodermic skin with abnormal keratinization. In their stratum corneum, degradation of nuclei and keratohyalin F-granules was incomplete and cell envelope assembly was defective. The skin barrier function of TGase 1-null mice was markedly impaired, and these mice died within 4–5 h after birth. These results clearly demonstrate that the TGase 1 gene is essential to the development and maturation of the stratum corneum and to adaptation to the environment after birth. Thus, these TGase 1 knockout mice may be a useful model for severe cases of LI.
The
Arthromitus
stage of
Bacillus cereus
: Intestinal symbionts of animals
Authors: Margulis Lynn , Jorgensen Jeremy Z. , Dolan Sona , Kolchinsky Rita , Rainey Frederick A. , Lo Shyh-Ching
Published: July 2002

In the guts of more than 25 species of arthropods we observed filaments containing refractile inclusions previously discovered and named “
Arthromitus
” in 1849 by Joseph Leidy [Leidy, J. (1849)
Proc. Acad. Nat. Sci. Philadelphia
4, 225–233]. We cultivated these microbes from boiled intestines of 10 different species of surface-cleaned soil insects and isopod crustaceans. Literature review and these observations lead us to conclude that
Arthromitus
are spore-forming, variably motile, cultivable bacilli. As long rod-shaped bacteria, they lose their flagella, attach by fibers or fuzz to the intestinal epithelium, grow filamentously, and sporulate from their distal ends. When these organisms are incubated in culture, their life history stages are accelerated by light and inhibited by anoxia. Characterization of new
Arthromitus
isolates from digestive tracts of common sow bugs (
Porcellio scaber
), roaches (
Gromphodorhina portentosa
,
Blaberus giganteus
) and termites (
Cryptotermes brevis
,
Kalotermes flavicollis)
identifies these flagellated, spore-forming symbionts as a
Bacillus
sp. Complete sequencing of the 16S rRNA gene from four isolates (two sow bug, one hissing roach, one death’s head roach) confirms these as the low-G+C Gram-positive eubacterium
Bacillus cereus
. We suggest that
B. cereus
and its close relatives, easily isolated from soil and grown on nutrient agar, enjoy filamentous growth in moist nutrient-rich intestines of healthy arthropods and similar habitats.
Genetic traces of ancient demography
Authors: Harpending Henry C. , Batzer Mark A. , Gurven Michael , Jorde Lynn B. , Rogers Alan R. , Sherry Stephen T.
Published: July 2002

Patterns of gene differences among humans contain information about the demographic history of our species. Haploid loci like mitochondrial DNA and the nonrecombining part of the Y chromosome show a pattern indicating expansion from a population of only several thousand during the late middle or early upper Pleistocene. Nuclear short tandem repeat loci also show evidence of this expansion. Both mitochondrial DNA and the Y chromosome coalesce within the last several hundred thousand years, and they cannot provide information about the population before their coalescence. Several nuclear loci are informative about our ancestral population size during nearly the whole Pleistocene. They indicate a small effective size, on the order of 10,000 breeding individuals, throughout this time period. This genetic evidence denies any version of the multiregional model of modern human origins. It implies instead that our ancestors were effectively a separate species for most of the Pleistocene.
SHOT, a SHOX-related homeobox gene, is implicated in craniofacial, brain, heart, and limb development
Authors: Blaschke Rüdiger J. , Monaghan A. Paula , Schiller Simone , Schechinger Birgit , Rao Ercole , Padilla-Nash Hesed , Ried Thomas , Rappold Gudrun A.
Published: July 2002

Deletion of the SHOX region on the human sex chromosomes has been shown to result in idiopathic short stature and proposed to play a role in the short stature associated with Turner syndrome. We have identified a human paired-related homeobox gene, SHOT, by virtue of its homology to the human SHOX and mouse OG-12 genes. Two different isoforms were isolated, SHOTa and SHOTb, which have identical homeodomains and share a C-terminal 14-amino acid residue motif characteristic for craniofacially expressed homeodomain proteins. Differences between SHOTa and b reside within the N termini and an alternatively spliced exon in the C termini.
In situ
hybridization of the mouse equivalent, OG-12, on sections from staged mouse embryos detected highly restricted transcripts in the developing sinus venosus (aorta), female genitalia, diencephalon, mes- and myelencephalon, nasal capsula, palate, eyelid, and in the limbs. SHOT was mapped to human chromosome 3q25-q26 and OG-12 within a syntenic region on chromosome 3. Based on the localization and expression pattern of its mouse homologue during embryonic development, SHOT represents a candidate for the Cornelia de Lange syndrome.
Thiolate ligands in metallothionein confer redox activity on zinc clusters
Authors: Maret Wolfgang , Vallee Bert L.
Published: July 2002

We postulate a novel and general mechanism in which the redox-active sulfur donor group of cyst(e)ine confers oxidoreductive characteristics on stable zinc sites in proteins. Thus, the present, an earlier, and accompanying manuscripts [Maret, W., Larsen, K. S. & Vallee, B. L. (1997)
Proc. Natl. Acad. Sci. USA
94, 2233–2237; Jiang, L.-J., Maret, W. & Vallee, B. L. (1998)
Proc. Natl. Acad. Sci. USA
95, 3483–3488; and Jacob, C., Maret, W. & Vallee, B. L. (1998)
Proc. Natl. Acad. Sci. USA
95, 3489–3494] demonstrate that the interactive network featuring multiple zinc/sulfur bonds as found in the clusters of metallothionein (MT) constitutes a coordination unit critical for the concurrent oxidation of cysteine ligands and the ensuing release of zinc. The low position of MT (<−366 mV) on a scale of redox reagents allows its effective oxidation by relatively mild cellular oxidants, in particular disulfides. When MT is exposed to an excess of dithiodipyridine, all of its 20 cysteines are oxidized within 1 hr with the concomitant release of all 7 zinc atoms; similarly, the thiol/disulfide oxidoreductase DsbA reacts stoichiometrically with MT to release zinc. Zinc and sulfur ligands in the clusters are in a spatial arrangement that seemingly favors disulfide bond formation. Jointly, this and the above-mentioned manuscripts conclude that the control of cellular zinc distribution as a function of the energy state of the cell is the long sought role of MT. This specific MT function renders dubious the widely held belief that MT primarily scavenges radicals or detoxifies metals and is consistent with the frequent use of cysteine as a zinc ligand in proteins as a means of both tight
and
weak zinc binding of thiols and disulfides, respectively. Thus, we relate changes in the reducing power of the cell to the stability of the zinc/sulfur network in MT and the relative mobility of zinc and its control.
Instability of signaling resolution models of parent–offspring conflict
Authors: Rodríguez-Gironés Miguel A. , Enquist Magnus , Cotton Peter A.
Published: July 2002

Recent signaling resolution models of parent–offspring conflict have provided an important framework for theoretical and empirical studies of communication and parental care. According to these models, signaling of need is stabilized by its cost. However, our computer simulations of the evolutionary dynamics of chick begging and parental investment show that in Godfray’s model the signaling equilibrium is evolutionarily unstable: populations that start at the signaling equilibrium quickly depart from it. Furthermore, the signaling and nonsignaling equilibria are linked by a continuum of equilibria where chicks above a certain condition do not signal and we show that, contrary to intuition, fitness increases monotonically as the proportion of young that signal decreases. This result forces us to reconsider much of the current literature on signaling of need and highlights the need to investigate the evolutionary stability of signaling equilibria based on the handicap principle.
CCR5+and CXCR3+T cells are increased in multiple sclerosis and their ligands MIP-1α and IP-10 are expressed in demyelinating brain lesions
Authors: Balashov Konstantin E. , Rottman James B. , Weiner Howard L. , Hancock Wayne W.
Published: July 2002

Multiple sclerosis (MS) is a T cell-dependent chronic inflammatory disease of the central nervous system. The role of chemokines in MS and its different stages is uncertain. Recent data suggest a bias in expression of chemokine receptors by Th1 vs. Th2 cells; human Th1 clones express CXCR3 and CCR5 and Th2 clones express CCR3 and CCR4. Chemokine receptors expressed by Th1 cells may be important in MS, as increased interferon-γ (IFN-γ) precedes clinical attacks, and IFN-γ injection induces disease exacerbations. We found CXCR3+T cells increased in blood of relapsing-remitting MS, and both CCR5+and CXCR3+T cells increased in progressive MS compared with controls. Furthermore, peripheral blood CCR5+T cells secreted high levels of IFN-γ. In the brain, the CCR5 ligand, MIP-1α, was strongly associated with microglia/macrophages, and the CXCR3 ligand, IP-10, was expressed by astrocytes in MS lesions but not unaffected white matter of control or MS subjects. Areas of plaque formation were infiltrated by CCR5-expressing and, to a lesser extent, CXCR3-expressing cells; Interleukin (IL)-18 and IFN-γ were expressed in demyelinating lesions. No leukocyte expression of CCR3, CCR4, or six other chemokines, or anti-inflammatory cytokines IL-5, IL-10, IL-13, and transforming growth factor-β was observed. Thus, chemokine receptor expression may be used for immunologic staging of MS and potentially for other chronic autoimmune/inflammatory processes such as rheumatoid arthritis, autoimmune diabetes, or chronic transplant rejection. Furthermore, these results provide a rationale for the use of agents that block CCR5 and/or CXCR3 as a therapeutic approach in the treatment of MS.
NFAT5, a constitutively nuclear NFAT protein that does not cooperate with Fos and Jun
Authors: López-Rodríguez Cristina , Aramburu José , Rakeman Andrew S. , Rao Anjana
Published: July 2002

NFAT transcription factors are related to NF-κB/Rel proteins and form cooperative complexes with Fos and Jun on DNA. We have identified an NFAT-related protein, NFAT5, which differs from the conventional NFAT proteins NFAT1–4 in its structure, DNA binding, and regulation. NFAT5 contains a NFAT-like Rel homology domain, conserves the DNA contact residues of NFAT1–4, and binds DNA sequences similar to those found in the regulatory regions of well-characterized NFAT-dependent genes. However, it lacks the majority of Fos/Jun contact residues and does not bind cooperatively with Fos and Jun to DNA. Unlike NFAT1–4, whose nuclear import is tightly regulated by calcineurin-mediated dephosphorylation, NFAT5 is a constitutively nuclear phosphoprotein regardless of calcineurin activation. These features suggest that unlike the conventional NFAT proteins, NFAT1–4, which activate gene transcription by integrating inputs from calcium/calcineurin and protein kinase C/mitogen-activated protein kinase signaling pathways, NFAT5 participates in as-yet-unidentified signaling pathways in diverse immune and nonimmune cells.
Atomic levers control pyranose ring conformations
Authors: Marszalek Piotr E. , Pang Yuan-Ping , Li Hongbin , Yazal Jamal El , Oberhauser Andres F. , Fernandez Julio M.
Published: July 2002

Atomic force microscope manipulations of single polysaccharide molecules have recently expanded conformational chemistry to include force-driven transitions between the chair and boat conformers of the pyranose ring structure. We now expand these observations to include chair inversion, a common phenomenon in the conformational chemistry of six-membered ring molecules. We demonstrate that by stretching single pectin molecules (1 → 4-linked α-
d
-galactouronic acid polymer), we could change the pyranose ring conformation from a chair to a boat and then to an inverted chair in a clearly resolved two-step conversion:
4
C
1
⇄
boat
⇄
1
C
4
. The two-step extension of the distance between the glycosidic oxygen atoms O
1
and O
4
determined by atomic force microscope manipulations is corroborated by
ab initio
calculations of the increase in length of the residue vector O
1
O
4
on chair inversion. We postulate that this conformational change results from the torque generated by the glycosidic bonds when a force is applied to the pectin molecule. Hence, the glycosidic bonds act as mechanical levers, driving the conformational transitions of the pyranose ring. When the glycosidic bonds are equatorial (e), the torque is zero, causing no conformational change. However, when the glycosidic bond is axial (a), torque is generated, causing a rotation around C—C bonds and a conformational change. This hypothesis readily predicts the number of transitions observed in pyranose monomers with 1a-4a linkages (two), 1a-4e (one), and 1e-4e (none). Our results demonstrate single-molecule mechanochemistry with the capability of resolving complex conformational transitions.
The protein kinase CK2 is involved in regulation of circadian rhythms in
Arabidopsis
Authors: Sugano Shoji , Andronis Christos , Ong May S. , Green Rachel M. , Tobin Elaine M.
Published: July 2002

A wide range of processes in plants, including expression of certain genes, is regulated by endogenous circadian rhythms. The circadian clock-associated 1 (CCA1) and the late elongated hypocotyl (LHY) proteins have been shown to be closely associated with clock function in
Arabidopsis thaliana
. The protein kinase CK2 can interact with and phosphorylate CCA1, but its role in the regulation of the circadian clock remains unknown. Here we show that plants overexpressing CKB3, a regulatory subunit of CK2, display increased CK2 activity and shorter periods of rhythmic expression of
CCA1
and
LHY
. CK2 is also able to interact with and phosphorylate LHY
in vitro
. Additionally, overexpression of
CKB3
shortened the periods of four known circadian clock-controlled genes with different phase angles, demonstrating that many clock outputs are affected. This overexpression also reduced phytochrome induction of an
Lhcb
gene. Finally, we found that the photoperiodic flowering response, which is influenced by circadian rhythms, was diminished in the transgenic lines, and that the plants flowered earlier on both long-day and short-day photoperiods. These data demonstrate that CK2 is involved in regulation of the circadian clock in
Arabidopsis
.
The
Escherichia coli
SOS mutagenesis proteins UmuD and UmuD′ interact physically with the replicative DNA polymerase
Authors: Sutton Mark D. , Opperman Timothy , Walker Graham C.
Published: July 2002

The
Escherichia coli
umuDC
operon is induced in response to replication-blocking DNA lesions as part of the SOS response. UmuD protein then undergoes an RecA-facilitated self-cleavage reaction that removes its N-terminal 24 residues to yield UmuD′. UmuD′, UmuC, RecA, and some form of the
E. coli
replicative DNA polymerase, DNA polymerase III holoenzyme, function in translesion synthesis, the potentially mutagenic process of replication over otherwise blocking lesions. Furthermore, it has been proposed that, before cleavage, UmuD together with UmuC acts as a DNA damage checkpoint system that regulates the rate of DNA synthesis in response to DNA damage, thereby allowing time for accurate repair to take place. Here we provide direct evidence that both uncleaved UmuD and UmuD′ interact physically with the catalytic, proofreading, and processivity subunits of the
E. coli
replicative polymerase. Consistent with our model proposing that uncleaved UmuD and UmuD′ promote different events, UmuD and UmuD′ interact differently with DNA polymerase III: whereas uncleaved UmuD interacts more strongly with β than it does with α, UmuD′ interacts more strongly with α than it does with β. We propose that the protein–protein interactions we have characterized are part of a higher-order regulatory system of replication fork management that controls when the
umuDC
gene products can gain access to the replication fork.
Aminopeptidase A inhibitors as potential central antihypertensive agents
Authors: Reaux Annabelle , Fournie-Zaluski Marie Claude , David Christelle , Zini Sylvie , Roques Bernard P. , Corvol Pierre , Llorens-Cortes Catherine
Published: July 2002

Overactivity of the brain renin-angiotensin system (RAS) has been
implicated in the development and maintenance of hypertension in
several experimental models, such as spontaneously hypertensive rats
and transgenic mice expressing both human renin and human
angiotensinogen transgenes. We recently reported that, in the murine
brain, angiotensin II (AngII) is converted to angiotensin III (AngIII)
by aminopeptidase A (APA), whereas AngIII is inactivated by
aminopeptidase N (APN). If injected into cerebral ventricles (ICV),
AngII and AngIII cause similar pressor responses. Because AngII is
metabolized
in vivo
into AngIII, the exact nature of the
active peptide is not precisely determined. Here we report that, in
rats, ICV injection of the selective APA inhibitor EC33
[(S)-3-amino-4-mercaptobutyl sulfonic acid] blocked the pressor
response of exogenous AngII, suggesting that the conversion of AngII to
AngIII is required to increase blood pressure (BP). Furthermore, ICV
injection, but not i.v. injection, of EC33 alone caused a
dose-dependent decrease in BP by blocking the formation of brain but
not systemic AngIII. This is corroborated by the fact that the
selective APN inhibitor, PC18 (2-amino-4-methylsulfonyl butane thiol),
administered alone via the ICV route, increases BP. This pressor
response was blocked by prior treatment with the angiotensin type 1
(AT
1
) receptor antagonist, losartan, showing that blocking
the action of APN on AngIII metabolism leads to an increase in
endogenous AngIII levels, resulting in BP increase, through
interaction with AT
1
receptors. These data demonstrate that
AngIII is a major effector peptide of the brain RAS, exerting tonic
stimulatory control over BP. Thus, APA, the enzyme responsible for the
formation of brain AngIII, represents a potential central therapeutic
target that justifies the development of APA inhibitors as central
antihypertensive agents.
Induced fit of a peptide loop of methionyl-tRNA formyltransferase triggered by the initiator tRNA substrate
Authors: Ramesh Vaidyanathan , Mayer Christine , Dyson Michael R. , Gite Sadanand , RajBhandary Uttam L.
Published: July 2002

A 16-aa insertion loop present in eubacterial methionyl-tRNA formyltransferases (MTF) is critical for specific recognition of the initiator tRNA in
Escherichia coli
. We have studied the interactions between this region of the
E. coli
enzyme and initiator methionyl-tRNA (Met-tRNA) by using two complementary protection experiments: protection of MTF against proteolytic cleavage by tRNA and protection of tRNA against nucleolytic cleavage by MTF. The insertion loop in MTF is uniquely sensitive to cleavage by trypsin. We show that the substrate initiator Met-tRNA protects MTF against trypsin cleavage, whereas a formylation-defective mutant initiator Met-tRNA, which binds to MTF with approximately the same affinity, does not. Also, mutants of MTF within the insertion loop (which are defective in formylation) are not protected by the initiator Met-tRNA. Thus, a functional enzyme–substrate complex is necessary for protection of MTF against trypsin cleavage. Along with other data, these results strongly suggest that a segment of the insertion loop, which is exposed and unstructured in MTF, undergoes an induced fit in the functional MTF⋅Met-tRNA complex but not in the nonfunctional one. Footprinting experiments show that MTF specifically protects the acceptor stem and the 3′-end region of the initiator Met-tRNA against cleavage by double and single strand-specific nucleases. This protection also depends on formation of a functional MTF⋅Met-tRNA complex. Thus, the insertion loop interacts mostly with the acceptor stem of the initiator Met-tRNA, which contains the critical determinants for formylation.
The RD114/simian type D retrovirus receptor is a neutral amino acid transporter
Authors: Rasko John E. J. , Battini Jean-Luc , Gottschalk Rebecca J. , Mazo Ilya , Miller A. Dusty
Published: July 2002

The RD114/simian type D retroviruses, which include the feline endogenous retrovirus RD114, all strains of simian immunosuppressive type D retroviruses, the avian reticuloendotheliosis group including spleen necrosis virus, and baboon endogenous virus, use a common cell-surface receptor for cell entry. We have used a retroviral cDNA library approach, involving transfer and expression of cDNAs from highly infectable HeLa cells to nonpermissive NIH 3T3 mouse cells, to clone and identify this receptor. The cloned cDNA, denoted RDR, is an allele of the previously cloned neutral amino acid transporter ATB
0
(SLC1A5). Both RDR and ATB
0
serve as retrovirus receptors and both show specific transport of neutral amino acids. We have localized the receptor by radiation hybrid mapping to a region of about 500-kb pairs on the long arm of human chromosome 19 at q13.3. Infection of cells with RD114/type D retroviruses results in impaired amino acid transport, suggesting a mechanism for virus toxicity and immunosuppression. The identification and functional characterization of this retrovirus receptor provide insight into the retrovirus life cycle and pathogenesis and will be an important tool for optimization of gene therapy using vectors derived from RD114/type D retroviruses.
Lymphocyte function-associated antigen-1 binding residues in intercellular adhesion molecule-2 (ICAM-2) and the integrin binding surface in the ICAM subfamily
Authors: Casasnovas José M. , Pieroni Cristiana , Springer Timothy A.
Published: July 2002

The crystal structure of intercellular adhesion molecule-2 (ICAM-2) revealed significant differences in the presentation of the critical acidic residue important for integrin binding between I and non-I-domain integrin ligands. Based on this crystal structure, we mutagenized ICAM-2 to localize the binding site for the integrin lymphocyte function-associated antigen-1 (LFA-1). The integrin binding site runs diagonally across the GFC β-sheet and includes residues on the CD edge of the β-sandwich. The site is oblong and runs along a flat ridge on the upper half of domain 1, which is proposed to dock to a groove in the I domain of LFA-1, with the critical Glu-37 residue ligating the Mg2+in the I domain. Previous mutagenesis of ICAM-1 and ICAM-3, interpreted in light of the recently determined ICAM-1 and ICAM-2 structures, suggests similar binding sites. By contrast, major differences are seen with vascular cell adhesion molecule-1 (VCAM-1), which binds α4integrins that lack an I domain. The binding site on VCAM-1 includes the lower portion of domain 1 and the upper part of domain 2, whereas the LFA-1 binding site on ICAM is confined to the upper part of domain 1.
Cooperative action of germ-line mutations in decorin and p53 accelerates lymphoma tumorigenesis
Authors: Iozzo Renato V. , Chakrani Fatima , Perrotti Danilo , McQuillan David J. , Skorski Tomasz , Calabretta Bruno , Eichstetter Inge
Published: July 2002

Ectopic expression of decorin in a wide variety of transformed cells results in growth arrest and the inability to generate tumors in nude mice. This process is caused by a decorin-mediated activation of the epidermal growth factor receptor, which leads to a sustained induction of endogenous p21
WAF1/CIP1
(the cyclin-dependent kinase inhibitor p21) and growth arrest. However, mice harboring a targeted disruption of the decorin gene do not develop spontaneous tumors. To test the role of decorin in tumorigenesis, we generated mice lacking both decorin and p53, an established tumor-suppressor gene. Mice lacking both genes showed a faster rate of tumor development and succumbed almost uniformly to thymic lymphomas within 6 months [mean survival age (T
50
) ∼4 months]. Mice harboring one decorin allele and no p53 gene developed the same spectrum of tumors as the double knockout animals, but had a survival rate similar to the p53 null animals (T
50
∼ 6 months). Ectopic expression of decorin in thymic lymphoma cells isolated from double mutant animals markedly suppressed their colony-forming ability. When these lymphoma cells were cocultured with fibroblasts derived from either wild-type or decorin null embryos, the cells grew faster in the absence of decorin. Moreover, exogenous decorin proteoglycan or its protein core significantly retarded their growth
in vitro
. These results indicate that the lack of decorin is permissive for lymphoma tumorigenesis in a mouse model predisposed to cancer and suggest that germ-line mutations in decorin and p53 may cooperate in the transformation of lymphocytes and ultimately lead to a more aggressive phenotype by shortening the tumor latency.
Failure to handle more than one internal representation in visual detection tasks
Authors: Gorea Andrei , Sagi Dov
Published: July 2002

Perceptual studies make a clear distinction between sensitivity and
decision criterion. The former is taken to characterize the processing
efficiency of the underlying sensory system and it increases with
stimulus strength. The latter is regarded as the manifestation of a
subjective operation whereby individuals decide on (as opposed to react
reflexively to) the occurrence of an event based on factors such as
expectation and payoff, in addition to its strength. To do so,
individuals need to have some knowledge of the internal response
distributions evoked by this event or its absence. In a natural,
behaviorally relevant multistimulus environment, observers must handle
many such independent distributions to optimize their decision
criteria. Here we show that they cannot do so. Instead, while leaving
sensitivity unchanged, lower and higher visibility events tend to be
reported respectively less and more frequently than when they are
presented in isolation. This behavior is in quantitative agreement with
predictions based on the notion that observers represent a
multistimulus environment as a unitary internal distribution to which
each stimulus contributes proportionally to its probability of
occurrence. Perceptual phenomena such as blindsight, hemineglect, and
extinction may be, at least in part, accounted for in such a way.
A role for
Salmonella
fimbriae in intraperitoneal infections
Authors: Edwards Robert A. , Schifferli Dieter M. , Maloy Stanley R.
Published: July 2002

Enteric bacteria possess multiple fimbriae, many of which play critical roles in attachment to epithelial cell surfaces. SEF14 fimbriae are only found in
Salmonella enterica
serovar Enteritidis (
S.
enteritidis
) and closely related serovars, suggesting that SEF14 fimbriae may affect serovar-specific virulence traits. Despite evidence that SEF14 fimbriae are expressed by
S.
enteritidis
in vivo
, previous studies showed that SEF14 fimbriae do not mediate adhesion to the intestinal epithelium. Therefore, we tested whether SEF14 fimbriae are required for virulence at a stage in infection after the bacteria have passed the intestinal barrier. Polar mutations that disrupt the entire
sef
operon decreased virulence in mice more than 1,000-fold. Nonpolar mutations that disrupted
sefA
(encoding the major structural subunit) did not affect virulence, but mutations that disrupted
sefD
(encoding the putative adhesion subunit) resulted in a severe virulence defect. The results indicate that the putative SEF14 adhesion subunit is specifically required for a stage of the infection subsequent to transit across the intestinal barrier. Therefore, we tested whether SefD is required for uptake or survival in macrophages. The majority of wild-type bacteria were detected inside macrophages soon after i.p. infection, but the
sefD
mutants were not readily internalized by peritoneal macrophages. These results indicate that the potential SEF14 adhesion subunit is essential for efficient uptake or survival of
S.
enteritidis
in macrophages. This report describes a role of fimbriae in intracellular infection, and indicates that fimbriae may be required for systemic infections at stages beyond the initial colonization of host epithelial surfaces.
Functional analysis of oxidative stress-activated mitogen-activated protein kinase cascade in plants
Authors: Kovtun Yelena , Chiu Wan-Ling , Tena Guillaume , Sheen Jen
Published: July 2002

Despite the recognition of H
2
O
2
as a central signaling molecule in stress and wounding responses, pathogen defense, and regulation of cell cycle and cell death, little is known about how the H
2
O
2
signal is perceived and transduced in plant cells. We report here that H
2
O
2
is a potent activator of mitogen-activated protein kinases (MAPKs) in
Arabidopsis
leaf cells. Using epitope tagging and a protoplast transient expression assay, we show that H
2
O
2
can activate a specific
Arabidopsis
mitogen-activated protein kinase kinase kinase, ANP1, which initiates a phosphorylation cascade involving two stress MAPKs, AtMPK3 and AtMPK6. Constitutively active ANP1 mimics the H
2
O
2
effect and initiates the MAPK cascade that induces specific stress-responsive genes, but it blocks the action of auxin, a plant mitogen and growth hormone. The latter observation provides a molecular link between oxidative stress and auxin signal transduction. Finally, we show that transgenic tobacco plants that express a constitutively active tobacco ANP1 orthologue, NPK1, display enhanced tolerance to multiple environmental stress conditions without activating previously described drought, cold, and abscisic acid signaling pathways. Thus, manipulation of key regulators of an oxidative stress signaling pathway, such as ANP1/NPK1, provides a strategy for engineering multiple stress tolerance that may greatly benefit agriculture.
15-Deoxy-Δ
12,14
-prostaglandin J
2
inhibits multiple steps in the NF-κB signaling pathway
Authors: Straus Daniel S. , Pascual Gabriel , Li Mei , Welch John S. , Ricote Mercedes , Hsiang Chin-Hui , Sengchanthalangsy Lei Lei , Ghosh Gourisankar , Glass Christopher K.
Published: July 2002

Prostaglandin J
2
(PGJ
2
) and its metabolites Δ
12
-PGJ
2
and 15-deoxy-Δ
12,14
-PGJ
2
(15d-PGJ
2
) are naturally occurring derivatives of prostaglandin D
2
that have been suggested to exert antiinflammatory effects
in vivo
. 15d-PGJ
2
is a high-affinity ligand for the peroxisome proliferator-activated receptor γ (PPARγ) and has been demonstrated to inhibit the induction of inflammatory response genes, including inducible NO synthase and tumor necrosis factor α, in a PPARγ-dependent manner. We report here that 15d-PGJ
2
potently inhibits NF-κB-dependent transcription by two additional PPARγ-independent mechanisms. Several lines of evidence suggest that 15d-PGJ
2
directly inhibits NF-κB-dependent gene expression through covalent modifications of critical cysteine residues in IκB kinase and the DNA-binding domains of NF-κB subunits. These mechanisms act in combination to inhibit transactivation of the NF-κB target gene cyclooxygenase 2. Direct inhibition of NF-κB signaling by 15d-PGJ
2
may contribute to negative regulation of prostaglandin biosynthesis and inflammation, suggesting additional approaches to the development of antiinflammatory drugs.
Uncertain identities and health‐risking behaviour: the case of young people and smoking in late modernity
Authors: Denscombe Martyn
Published: July 2002

This paper argues that ‘uncertain identities’ are a distinct contributing factor to the residual and intractable level of smoking among young people. Further, it argues that the significance of this factor is increased by the specific social/historical context of late modernity. Findings from research with 15 to 16 year olds in the East Midlands of England are used to explore the role that smoking is perceived to play in constructing a self identity. A voluntaristic perspective is adopted on the use of tobacco, reflecting both the focus on young people's motivation to smoke and the tendency for many young people to perceive smoking as a matter of personal choice. Smoking was found to have a symbolic significance not only in terms of the presentation of self to others but also in terms of the reflexive construction of the self by those involved. The paper analyses the role of smoking in relation to self‐image, self‐empowerment and self‐affirmation and it is concluded that for many young people smoking has certain benefits in terms of coping with uncertain identities.
Shaping of scientific psychology in Japan
Authors: Oyama Tadasu , Sato Tatsuya , Suzuki Yuko
Published: July 2002

Japanese scientific psychology began with Y. Motora's lecture on pyschophysics at the University of Tokyo in 1888. He had just received his PhD under G.S. Hall at Johns Hopkins University, in the USA. He became the first professor of psychology in 1890 and founded the first psychological laboratory at the University of Tokyo in 1903. He studied many psychological problems, including attention, experimentally and theoretically. One of his first students, Matataro Matsumoto, founded the second psychological laboratory at Kyoto University and then succeeded to Motora's position in Tokyo. Matsumoto was interested in experimental studies of human performance and their applications. He trained many able psychologists and organized the Japanese Psychological Association in 1927. Some of his students founded more psychological laboratories in major universities of Japan. They introduced psychological tests, Gestalt psychology, and behaviourism in the 1920s and 1930s. Psychoanalysis was introduced through mainly nonacademic roots and became familiar to Japanese psychologists in the 1930s. After World War II, a strong influence of American psychology came to Japanese psychologists who had already trained in scientific methodology. The areas of research and applications have been greatly widened and the number of psychologists has increased rapidly up to the present day. Promotion of international interactions and indigenous traditions are both expected.
Cognitive Bias to Internal Sources of Information in Anxiety
Authors: Calvo Manuel G. , Eysenck Michael W.
Published: July 2002

Discrepancies between (a) self‐reported psychosomatic symptoms and (b) actual fitness under non‐stress (Study 1), as a function of trait anxiety, were examined, as well as discrepancies between (a) self‐reported cognitive and somatic state anxiety and (b) objective measures of behavioural reactivity, physiological arousal, and performance under social‐evaluative stress (Study 2). Results indicated that persons high in trait anxiety exaggerated distress in both conditions: They showed disproportionately greater self‐reported concerns than actual problems. In contrast, those low in anxiety minimized distress (lower self‐reported than actual problems). These discrepancy phenomena are explained in terms of biases in the processing of internal sources of information.
Community Resources and Opportunities in Ethnic Economies: A Case Study of Portuguese and Black Entrepreneurs in Toronto
Authors: Teixeira Carlos
Published: July 2002

Relatively few attempts have been made by geographers in Canada to study the structure and development of ethnic entrepreneurship among immigrant groups, and particularly among visible minorities. The purpose of this study is to examine the behaviour, strategies and barriers faced by owners of ethnic businesses in order to evaluate how race and ethnicity impact upon entrepreneurship. In particular, the study aims at investigating whether intergroup differences exist with respect to the utilisation of group resources (such as family, friends, and community support/ties) and how these resources contribute to the formation, maintenance and success of Portuguese- and Black-owned businesses. Data were obtained from a questionnaire survey that was administered to Portuguese and Black entrepreneurs in the Toronto CMA. The evidence indicates that Portuguese differ significantly from Black entrepreneurs in that they rely more often on their community ('ethnic') resources. However, Black entrepreneurs encountered more barriers in starting and/or operating their current business, particularly in obtaining credit/loans from financial institutions and banks. Nonetheless, despite such barriers, Black entrepreneurs are more optimistic than the Portuguese with respect to the future of their businesses. The 'demographic revolution' that is taking place in Canada, and particularly in Toronto—with the arrival of important contingents of visible minorities—is pointed to by Black entrepreneurs as one of the major reasons for their optimism regarding the growth of Black entrepreneurship in Toronto.
A Hybrid Agglomeration? The Development of a Satellite-Marshallian Industrial District in Vancouver's Film Industry
Authors: Coe Neil M.
Published: July 2002

The new industrial district is now seen as one of several dynamic regional formations that may co-exist in contemporary economies. In addition to the traditional Marshallian or Italianate variety, Markusen has suggested three other forms of industrial district: the hub-and-spoke district, the satellite platform and the state-anchored district. In this article, developments within the North American film industry are used to illustrate the dynamics of a 'hybrid' industrial district form, which is termed the satellite-Marshallian district. A detailed case study is presented of the film production complex in Vancouver, which has risen to prominence as Hollywood studios and television networks have continued to increase their offshore location shooting. The analysis is based upon a series of in-depth interviews undertaken with key agents associated with the Vancouver film industry in the second half of 1997.