bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of unique leucine-zipper motif of PSD-Zip45 (Homer 1c/vesl-1L) in group 1 metabotropic glutamate receptor clustering
Authors: Tadokoro Satoko , Tachibana Taro , Imanaka Takanobu , Nishida Wataru , Sobue Kenji
Published: July 2002

Several scaffold proteins for neurotransmitter receptors have been identified as candidates for receptor targeting. However, the molecular mechanism underlying such receptor clustering and targeting to postsynaptic specializations remains unknown. PSD-Zip45 (also named Homer 1c/vesl-1L) consists of the NH
2
terminus containing the enabled/VASP homology 1 domain and the COOH terminus containing the leucine zipper. Here, we demonstrate immunohistochemically that metabotropic glutamate receptor 1α (mGluR1α) and PSD-Zip45/Homer 1c are colocalized to synapses in the cerebellar molecular layer but not in the hippocampus. In cultured hippocampal neurons, PSD-Zip45/Homer1c and
N
-methyl-
d-
aspartate receptors are preferentially colocalized to dendritic spines. Cotransfection of mGluR1α or mGluR5 and PSD-Zip45/Homer 1c into COS-7 cells results in mGluR clustering induced by PSD-Zip45/Homer 1c. An
in vitro
multimerization assay shows that the extreme COOH-terminal leucine zipper is involved in self-multimerization of PSD-Zip45/Homer 1c. A clustering assay of mGluRs in COS-7 cells also reveals a critical role of this leucine-zipper motif of PSD-Zip45/Homer 1c in mGluR clustering. These results suggest that the leucine zipper of subsynaptic scaffold protein is a candidate motif involved in neurotransmitter receptor clustering at the central synapse.
The mechanism of pseudouridine synthase I as deduced from its interaction with 5-fluorouracil-tRNA
Authors: Gu Xiangrong , Liu Yaoquan , Santi Daniel V.
Published: July 2002

tRNA pseudouridine synthase I (ΨSI) catalyzes the conversion of uridine to Ψ at positions 38, 39, and/or 40 in the anticodon loop of tRNAs. ΨSI forms a covalent adduct with 5-fluorouracil (FUra)-tRNA (tRNA
Phe
containing FUra in place of Ura) to form a putative analog of a steady-state intermediate in the normal reaction pathway. Previously, we proposed that a conserved aspartate of the enzyme serves as a nucleophilic catalyst in both the normal enzyme reaction and in the formation of a covalent complex with FUra-tRNA. The covalent adduct between FUra-tRNA and ΨSI was isolated and disrupted by hydrolysis and the FUra-tRNA was recovered. The target FU39 of the recovered FUra-tRNA was modified by the addition of water across the 5,6-double bond of the pyrimidine base to form 5,6-dihydro-6-hydroxy-5-fluorouridine. We deduced that the conserved aspartate of the enzyme adds to the 6-position of the target FUra to form a stable covalent adduct, which can undergo
O-
acyl hydrolytic cleavage to form the observed product. Assuming that an analogous covalent complex is formed in the normal reaction, we have deduced a complete mechanism for ΨS.
Hematopoietic potential of stem cells isolated from murine skeletal muscle
Authors: Jackson Kathyjo Ann , Mi Tiejuan , Goodell Margaret A.
Published: July 2002

We have discovered that cells derived from the skeletal muscle of adult mice contain a remarkable capacity for hematopoietic differentiation. Cells prepared from muscle by enzymatic digestion and 5-day
in vitro
culture were harvested, and 18 × 10
3
cells were introduced into each of six lethally irradiated recipients together with 200 × 10
3
distinguishable whole bone marrow cells. After 6 or 12 weeks, all recipients showed high-level engraftment of muscle-derived cells representing all major adult blood lineages. The mean total contribution of muscle cell progeny to peripheral blood was 56 ± 20% (SD), indicating that the cultured muscle cells generated approximately 10- to 14-fold more hematopoietic activity than whole bone marrow. When bone marrow from one mouse was harvested and transplanted into secondary recipients, all recipients showed high-level multilineage engraftment (mean 40%), establishing the extremely primitive nature of these stem cells. We also show that muscle contains a population of cells with several characteristics of bone marrow-derived hematopoietic stem cells, including high efflux of the fluorescent dye Hoechst 33342 and expression of the stem cell antigens Sca-1 and c-Kit, although the cells lack the hematopoietic marker CD45. We propose that this population accounts for the hematopoietic activity generated by cultured skeletal muscle. These putative stem cells may be identical to muscle satellite cells, some of which lack myogenic regulators and could be expected to respond to hematopoietic signals.
Lethal paralysis of
Caenorhabditis elegans
by
Pseudomonas
aeruginosa
Authors: Darby Creg , Cosma Christine L. , Thomas James H. , Manoil Colin
Published: July 2002

Identification of host factors that interact with pathogens is crucial to an understanding of infectious disease, but direct screening for host mutations to aid in this task is not feasible in mammals. The nematode
Caenorhabditis elegans
is a genetically tractable alternative for investigating the pathogenic bacterium
Pseudomonas aeruginosa
. A
P. aeruginosa
toxin, produced at high cell density under control of the quorum-sensing regulators LasR and RhlR, rapidly and lethally paralyzes
C. elegans
. Loss-of-function mutations in
C. elegans egl-9
, a gene required for normal egg laying, confer strong resistance to the paralysis. Thus, activation of EGL-9 or of a pathway that includes it may lead to the paralysis. The molecular identity of
egl-9
was determined by transformation rescue and DNA sequencing. A mammalian homologue of EGL-9 is expressed in tissues in which exposure to
P. aeruginosa
could have clinical effects.
Molecular characterization of a mutable pigmentation phenotype and isolation of the first active transposable element from
Sorghum bicolor
Authors: Chopra Surinder , Brendel Volker , Zhang Jianbo , Axtell John D. , Peterson Thomas
Published: July 2002

Accumulation of red phlobaphene pigments in sorghum grain pericarp is under the control of the
Y
gene. A mutable allele of
Y
, designated as
y-cs
(
y-candystripe
), produces a variegated pericarp phenotype. Using probes from the maize
p1
gene that cross-hybridize with the sorghum
Y
gene, we isolated the
y-cs
allele containing a large insertion element. Our results show that the
Y
gene is a member of the
MYB-
transcription factor family. The insertion element, named
Candystripe1
(
Cs1
), is present in the second intron of the
Y
gene and shares features of the CACTA superfamily of transposons.
Cs1
is 23,018 bp in size and is bordered by 20-bp terminal inverted repeat sequences. It generated a 3-bp target site duplication upon insertion within the
Y
gene and excised from
y-cs
, leaving a 2-bp footprint in two cases analyzed. Reinsertion of the excised copy of
Cs1
was identified by Southern hybridization in the genome of each of seven red pericarp revertant lines tested.
Cs1
is the first active transposable element isolated from sorghum. Our analysis suggests that
Cs1
-homologous sequences are present in low copy number in sorghum and other grasses, including sudangrass, maize, rice, teosinte, and sugarcane. The low copy number and high transposition frequency of
Cs1
imply that this transposon could prove to be an efficient gene isolation tool in sorghum.
Trimeric domain-swapped barnase
Authors: Zegers Ingrid , Deswarte Joeri , Wyns Lode
Published: July 2002

The structure of a trimeric domain-swapped form of barnase (EC
3.1.27.3
) was determined by x-ray crystallography at a resolution of 2.2 Å from crystals of space group
R
32. Residues 1–36 of one molecule associate with residues 41–110 from another molecule related through threefold symmetry. The resulting cyclic trimer contains three protein folds that are very similar to those in monomeric barnase. Both swapped domains contain a nucleation site for folding. The formation of a domain-swapped trimer is consistent with the description of the folding process of monomeric barnase as the formation and subsequent association of two foldons.
Enhanced rate of intramolecular electron transfer in an engineered purple Cu
A
azurin
Authors: Farver Ole , Lu Yi , Ang Majorie C. , Pecht Israel
Published: July 2002

The recent expression of an azurin mutant where the blue type 1 copper site is replaced by the purple Cu
A
site of
Paracoccus denitrificans
cytochrome
c
oxidase has yielded an optimal system for examining the unique electron mediation properties of the binuclear Cu
A
center, because both type 1 and Cu
A
centers are placed in the same location in the protein while all other structural elements remain the same. Long-range electron transfer is induced between the disulfide radical anion, produced pulse radiolytically, and the oxidized binuclear Cu
A
center in the purple azurin mutant. The rate constant of this intramolecular process,
k
ET
= 650 ± 60 s
−1
at 298 K and pH 5.1, is almost 3-fold faster than for the same process in the wild-type single blue copper azurin from
Pseudomonas aeruginosa
(250 ± 20 s
−1
), in spite of a smaller driving force (0.69 eV for purple Cu
A
azurin vs. 0.76 eV for blue copper azurin). The reorganization energy of the Cu
A
center is calculated to be 0.4 eV, which is only 50% of that found for the wild-type azurin. These results represent a direct comparison of electron transfer properties of the blue and purple Cu
A
sites in the same protein framework and provide support for the notion that the binuclear purple Cu
A
center is a more efficient electron transfer agent than the blue single copper center because reactivity of the former involves a lower reorganization energy.
An inducible gene product for 6-phosphofructo-2-kinase with an AU-rich instability element: Role in tumor cell glycolysis and the Warburg effect
Authors: Chesney Jason , Mitchell Robert , Benigni Fabio , Bacher Michael , Spiegel Lori , Al-Abed Yousef , Han Jung Hee , Metz Christine , Bucala Richard
Published: July 2002

Cancer cells maintain a high glycolytic rate even in the presence of oxygen, a phenomenon first described over 70 years ago and known historically as the Warburg effect. Fructose 2,6-bisphosphate is a powerful allosteric regulator of glycolysis that acts to stimulate the activity of 6-phosphofructo-1-kinase (PFK-1), the most important control point in mammalian glycolysis. The steady state concentration of fructose 2,6-bisphosphate in turn depends on the activity of the enzyme 6-phosphofructo-2-kinase (PFK-2)/fructose-2,6-bisphosphatase, which is expressed in several tissue-specific isoforms. We report herein the identification of a gene product for this enzyme that is induced by proinflammatory stimuli and which is distinguished by the presence of multiple copies of the AUUUA mRNA instability motif in its 3′-untranslated end. This inducible gene for PFK-2 is expressed constitutively in several human cancer cell lines and was found to be required for tumor cell growth
in vitro
and
in vivo
. Inhibition of inducible PFK-2 protein expression decreased the intracellular level of 5-phosphoribosyl-1-pyrophosphate, a product of the pentose phosphate pathway and an important precursor for nucleic acid biosynthesis. These studies identify a regulatory isoenzyme that may be essential for tumor growth and provide an explanation for long-standing observations concerning the apparent coupling of enhanced glycolysis and cell proliferation.
Plaque-independent disruption of neural circuits in Alzheimer’s disease mouse models
Authors: Hsia Albert Y. , Masliah Eliezer , McConlogue Lisa , Yu Gui-Qiu , Tatsuno Gwen , Hu Kang , Kholodenko Dora , Malenka Robert C. , Nicoll Roger A. , Mucke Lennart
Published: July 2002

Autosomal dominant forms of familial Alzheimer’s disease (FAD) are associated with increased production of the amyloid β peptide, Aβ42, which is derived from the amyloid protein precursor (APP). In FAD, as well as in sporadic forms of the illness, Aβ peptides accumulate abnormally in the brain in the form of amyloid plaques. Here, we show that overexpression of FAD(717
V→F
)-mutant human APP in neurons of transgenic mice decreases the density of presynaptic terminals and neurons well before these mice develop amyloid plaques. Electrophysiological recordings from the hippocampus revealed prominent deficits in synaptic transmission, which also preceded amyloid deposition by several months. Although in young mice, functional and structural neuronal deficits were of similar magnitude, functional deficits became predominant with advancing age. Increased Aβ production in the context of decreased overall APP expression, achieved by addition of the Swedish FAD mutation to the APP transgene in a second line of mice, further increased synaptic transmission deficits in young APP mice without plaques. These results suggest a neurotoxic effect of Aβ that is independent of plaque formation.
Cyclopentenone prostaglandins suppress activation of microglia: Down-regulation of inducible nitric-oxide synthase by 15-deoxy-Δ
12,14
-prostaglandin J
2
Authors: Petrova Tatiana V. , Akama Keith T. , Van Eldik Linda J.
Published: July 2002

Mechanisms leading to down-regulation of activated microglia and astrocytes are poorly understood, in spite of the potentially detrimental role of activated glia in neurodegeneration. Prostaglandins, produced both by neurons and glia, may serve as mediators of glial and neuronal functions. We examined the influence of cyclopentenone prostaglandins and their precursors on activated glia. As models of glial activation, production of inducible nitric-oxide synthase (iNOS) was studied in lipopolysaccharide-stimulated rat microglia, a murine microglial cell line BV-2, and IL-1β-stimulated rat astrocytes. Cyclopentenone prostaglandins were potent inhibitors of iNOS induction and were more effective than their precursors, prostaglandins E
2
and D
2
. 15-Deoxy-Δ
12,14
-prostaglandin J
2
(15d-PGJ
2
) was the most potent prostaglandin among those tested. In activated microglia, 15d-PGJ
2
suppressed iNOS promoter activity, iNOS mRNA, and protein levels. The action of 15d-PGJ
2
does not appear to involve its nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) because troglitazone, a specific ligand of PPARγ, was unable to inhibit iNOS induction, and neither troglitazone nor 15d-PGJ
2
could stimulate the activity of a PPAR-dependent promoter in the absence of cotransfected PPARγ. 15d-PGJ
2
did not block nuclear translocation or DNA-binding activity of the transcription factor NFκB, but it did inhibit the activity of an NFκB reporter construct, suggesting that the mechanism of suppression of microglial iNOS by 15d-PGJ
2
may involve interference with NFκB transcriptional activity in the nucleus. Thus, our data suggest the existence of a novel pathway mediated by cyclopentenone prostaglandins, which may represent part of a feedback mechanism leading to the cessation of inflammatory glial responses in the brain.
Chimeric green fluorescent protein-aequorin as bioluminescent Ca
2+
reporters at the single-cell level
Authors: Baubet Valérie , Le Mouellic Hervé , Campbell Anthony K. , Lucas-Meunier Estelle , Fossier Philippe , Brûlet Philippe
Published: July 2002

Monitoring calcium fluxes in real time could help to understand the development, the plasticity, and the functioning of the central nervous system. In jellyfish, the chemiluminescent calcium binding aequorin protein is associated with the green fluorescent protein and a green bioluminescent signal is emitted upon Ca
2+
stimulation. We decided to use this chemiluminescence resonance energy transfer between the two molecules. Calcium-sensitive bioluminescent reporter genes have been constructed by fusing green fluorescent protein and aequorin, resulting in much more light being emitted. Chemiluminescent and fluorescent activities of these fusion proteins have been assessed in mammalian cells. Cytosolic Ca
2+
increases were imaged at the single-cell level with a cooled intensified charge-coupled device camera. This bifunctional reporter gene should allow the investigation of calcium activities in neuronal networks and in specific subcellular compartments in transgenic animals.
Myosin-V stepping kinetics: A molecular model for processivity
Authors: Rief Matthias , Rock Ronald S. , Mehta Amit D. , Mooseker Mark S. , Cheney Richard E. , Spudich James A.
Published: July 2002

Myosin-V is a molecular motor that moves processively along its actin track. We have used a feedback-enhanced optical trap to examine the stepping kinetics of this movement. By analyzing the distribution of time periods separating discrete ≈36-nm mechanical steps, we characterize the number and duration of rate-limiting biochemical transitions preceding each such step. These data show that myosin-V is a tightly coupled motor whose cycle time is limited by ADP release. On the basis of these results, we propose a model for myosin-V processivity.
Serotonin 2B receptor is required for heart development
Authors: Nebigil Canan G. , Choi Doo-Sup , Dierich Andrée , Hickel Pierre , Le Meur Marianne , Messaddeq Nadia , Launay Jean-Marie , Maroteaux Luc
Published: July 2002

Several lines of evidence suggest that the serotonin (5-hydroxytryptamine, 5-HT) regulates cardiovascular functions during embryogenesis and adulthood. 5-HT binds to numerous cognate receptors to initiate its biological effects. However, none of the 5-HT receptor disruptions in mice have yet resulted in embryonic defects. Here we show that 5-HT
2B
receptor is an important regulator of cardiac development. We found that inactivation of 5-HT
2B
gene leads to embryonic and neonatal death caused by heart defects. 5-HT
2B
mutant embryos exhibit a lack of trabeculae in the heart and a specific reduction in the expression levels of a tyrosine kinase receptor, ErbB-2, leading to midgestation lethality. These
in vivo
data suggest that the Gq-coupled receptor 5-HT
2B
uses the signaling pathway of tyrosine kinase receptor ErbB-2 for cardiac differentiation. All surviving newborn mice display a severe ventricular hypoplasia caused by impaired proliferative capacity of myocytes. In adult mutant mice, cardiac histopathological changes including myocyte disarray and ventricular dilation were consistently observed. Our results constitute genetic evidence that 5-HT via 5-HT
2B
receptor regulates differentiation and proliferation of developing and adult heart. This mutation provides a genetic model for cardiopathy and should facilitate studies of both the pathogenesis and therapy of cardiac disorders in humans.
Involvement of decidual Vα14 NKT cells in abortion
Authors: Ito Katsura , Karasawa Mika , Kawano Tetsu , Akasaka Takeshi , Koseki Haruhiko , Akutsu Yasunori , Kondo Eisuke , Sekiya Souei , Sekikawa Kenji , Harada Michishige , Yamashita Masakatsu , Nakayama Toshinori , Taniguchi Masaru
Published: July 2002

The immunological mechanisms that regulate abortion are largely unknown. Here, we found that a distinct subset of lymphocytes, Vα14 NKT cells expressing an invariant antigen receptor encoded by Vα14/Jα281 and Vβ7 segments, accumulated in the decidua during pregnancy and provoked abortion upon stimulation with α-galactosylceramide (α-GalCer), a specific ligand for Vα14 NKT cells. The α-GalCer-mediated abortion was not observed in Vα14 NKT-, IFN-γ-, tumor necrosis factor α-, or perforin-knock-out mice and appeared to be due to the degeneration of embryonic trophoblasts mediated by the activated Vα14 NKT cells whose perforin-dependent killing and production of IFN-γ and tumor necrosis factor α were essential. The possible role of the decidual Vα14 NKT cells in the pathogenesis of abortion is discussed.
Crystal structure of yeast initiation factor 4A, a DEAD-box RNA helicase
Authors: Caruthers Jonathan M. , Johnson Eric R. , McKay David B.
Published: July 2002

The eukaryotic translation initiation factor 4A (eIF4A) is a
member of the DEA(D/H)-box RNA helicase family, a diverse group of
proteins that couples an ATPase activity to RNA binding and unwinding.
Previous work has provided the structure of the amino-terminal,
ATP-binding domain of eIF4A. Extending those results, we have solved
the structure of the carboxyl-terminal domain of eIF4A with data to
1.75 Å resolution; it has a parallel α-β topology that
superimposes, with minor variations, on the structures and conserved
motifs of the equivalent domain in other, distantly related helicases.
Using data to 2.8 Å resolution and molecular replacement with the
refined model of the carboxyl-terminal domain, we have completed the
structure of full-length eIF4A; it is a “dumbbell” structure
consisting of two compact domains connected by an extended linker. By
using the structures of other helicases as a template, compact
structures can be modeled for eIF4A that suggest (
i
)
helicase motif IV binds RNA; (
ii
) Arg-298, which is
conserved in the DEA(D/H)-box RNA helicase family but is absent from
many other helicases, also binds RNA; and (
iii
) motifs V
and VI “link” the carboxyl-terminal domain to the amino-terminal
domain through interactions with ATP and the DEA(D/H) motif,
providing a mechanism for coupling ATP binding and hydrolysis with
conformational changes that modulate RNA binding.
Explaining the high mutation rates of cancer cells to drug and multidrug resistance by chromosome reassortments that are catalyzed by aneuploidy
Authors: Duesberg Peter , Stindl Reinhard , Hehlmann Rüediger
Published: July 2002

The mutation rates of cancer cells to drug and multidrug
resistance are paradoxically high, i.e., 10
−3
to
10
−6
, compared with those altering phenotypes of recessive
genes in normal diploid cells of about 10
−12
. Here the
hypothesis was investigated that these mutations are due to chromosome
reassortments that are catalyzed by aneuploidy. Aneuploidy, an abnormal
number of chromosomes, is the most common genetic abnormality of cancer
cells and is known to change phenotypes (e.g., Down's syndrome).
Moreover, we have shown recently that aneuploidy autocatalyzes
reassortments of up to 2% per chromosome per mitosis because it
unbalances spindle proteins, even centrosome numbers, via gene dosage.
The hypothesis predicts that a selected phenotype is associated with
multiple unselected ones, because chromosome reassortments unbalance
simultaneously thousands of regulatory and structural genes. It also
predicts variants of a selected phenotype based on variant
reassortments. To test our hypothesis we have investigated in parallel
the mutation rates of highly aneuploid and of normal diploid Chinese
hamster cells to resistance against puromycin, cytosine arabinoside,
colcemid, and methotrexate. The mutation rates of aneuploid cells
ranged from 10
−4
to 10
−6
, but no
drug-resistant mutants were obtained from diploid cells in our
conditions. Further selection increased drug resistance at similar
mutation rates. Mutants selected from cloned cells for resistance
against one drug displayed different unselected phenotypes, e.g.,
polygonal or fusiform cellular morphology, flat or three-dimensional
colonies, and resistances against other unrelated drugs. Thus our
hypothesis offers a unifying explanation for the high mutation rates of
aneuploid cancer cells and for the association of selected with
unselected phenotypes, e.g., multidrug resistance. It also predicts
drug-specific chromosome combinations that could become a basis for
selecting alternative chemotherapy against drug-resistant cancer.
Mosaic blood vessels in tumors: Frequency of cancer cells in contact with flowing blood
Authors: Chang Yong S. , di Tomaso Emmanuelle , McDonald Donald M. , Jones Rosemary , Jain Rakesh K. , Munn Lance L.
Published: July 2002

The presence of “mosaic” vessels in which both endothelial
cells and tumor cells form the luminal surface has profound
implications for metastasis, drug delivery, and antivascular therapy.
Yet little is known of the frequency, and thus importance, of mosaic
vessels in tumors. Using CD31 and CD105 to identify endothelial cells
and endogenous green fluorescent protein labeling of tumor
cells, we show that ≈15% of perfused vessels of a colon carcinoma
xenografted at two different sites in mice were mosaic vessels having
focal regions where no CD31/CD105 immunoreactivity was detected and
tumor cells appeared to contact the vessel lumen. These regions
occupied ≈25% of the perimeter of the mosaic vessels, or ≈4% of
the total vascular surface area in these colon carcinomas. In addition,
we found similar numbers of mosaic vessels in human colon carcinoma
biopsies. Our results are consistent with the observation that
≈10
6
cells are shed daily per g of tumor. More
importantly, our data offer a possible explanation for the antivascular
effects of cytotoxic agents and suggest potential strategies for
targeting the tumor vasculature.
Regulation of Smad degradation and activity by Smurf2, an E3 ubiquitin ligase
Authors: Zhang Ying , Chang Chenbei , Gehling Daniel J. , Hemmati-Brivanlou Ali , Derynck Rik
Published: July 2002

Smad proteins are key intracellular signaling effectors for the
transforming growth factor-β superfamily of peptide growth factors.
Following receptor-induced activation, Smads move into the nucleus to
activate transcription of a select set of target genes. The activity of
Smad proteins must be tightly regulated to exert the biological effects
of different ligands in a timely manner. Here, we report the
identification of Smurf2, a new member of the Hect family of E3
ubiquitin ligases. Smurf2 selectively interacts with receptor-regulated
Smads and preferentially targets Smad1 for ubiquitination and
proteasome-mediated degradation. At higher expression levels, Smurf2
also decreases the protein levels of Smad2, but not Smad3. In
Xenopus
embryos, ectopic Smurf2 expression specifically
inhibits Smad1 responses and thereby affects embryonic patterning by
bone morphogenetic protein signals. These findings suggest that Smurf2
may regulate the competence of a cell to respond to transforming growth
factor-β/bone morphogenetic protein signaling through a distinct
degradation pathway that is similar to, yet independent of, Smurf1.
Vascular tumors in livers with targeted inactivation of the von Hippel–Lindau tumor suppressor
Authors: Haase Volker H. , Glickman Jonathan N. , Socolovsky Merav , Jaenisch Rudolf
Published: July 2002

von Hippel–Lindau (VHL) disease is a pleomorphic familial
tumor syndrome that is characterized by the development of highly
vascularized tumors. Homozygous disruption of the
VHL
gene in mice results in embryonic lethality. To investigate
VHL
function in the adult we have generated a
conditional
VHL
null allele (2-
lox
allele) and null allele (1-
lox
allele) by Cre-mediated
recombination in embryonic stem cells. We show here that mice
heterozygous for the 1-
lox
allele develop cavernous
hemangiomas of the liver, a rare manifestation of the human disease.
Histologically these tumors were associated with hepatocellular
steatosis and focal proliferations of small vessels. To study the
cellular origin of these lesions we inactivated
VHL
tissue-specifically in hepatocytes. Deletion of
VHL
in
the liver resulted in severe steatosis, many blood-filled vascular
cavities, and foci of increased vascularization within the hepatic
parenchyma. These histopathological changes were similar to those seen
in livers from mice heterozygous for the 1-
lox
allele.
Hypoxia-inducible mRNAs encoding vascular endothelial growth factor,
glucose transporter 1, and erythropoietin were up-regulated. We thus
provide evidence that targeted inactivation of mouse
VHL
can model clinical features of the human disease and underline the
importance of the
VHL
gene product in the regulation of
hypoxia-responsive genes
in vivo
.
Mitochondria in eosinophils: Functional role in apoptosis but not respiration
Authors: Peachman Kristina K. , Lyles Douglas S. , Bass David A.
Published: July 2002

In most eukaryotic cells, mitochondria use the respiratory chain to produce a proton gradient, which is then harnessed for the synthesis of ATP. Recently, mitochondrial roles in regulation of apoptosis have been discovered in many cell types. Eosinophils (Eos) die by apoptosis, but the presence and function of mitochondria in Eos are unknown. This study found that Eos contain mitochondria in small numbers, as shown by labeling with membrane potential-sensitive dyes andin situPCR for a mitochondrial gene. Eos generate mitochondrial membrane potential from hydrolysis of ATP rather than from respiration, as shown by mitochondrial respiratory inhibitors and mitochondrial uncouplers. The mitochondria provide insignificant respiration but can induce apoptosis, as shown by using the mitochondrial F1F0-ATPase inhibitor oligomycin and translocation of cytochromec.Thus during differentiation of Eos, although respiration is lost, the other central role of mitochondria, the induction of apoptosis, is retained.
A thrombin receptor function for platelet glycoprotein Ib–IX unmasked by cleavage of glycoprotein V
Authors: Ramakrishnan Vanitha , DeGuzman Francis , Bao Ming , Hall Scott W. , Leung Lawrence L. , Phillips David R.
Published: July 2002

Glycoprotein (GP) V is a major substrate cleaved by the
protease thrombin during thrombin-induced platelet activation. Previous
analysis of platelets from GP V-null mice suggested a role for GP V as
a negative modulator of platelet activation by thrombin. We now report
the mechanism by which thrombin activates GP V −/− platelets. We
show that proteolytically inactive forms of thrombin induce robust
stimulatory responses in GP V null mouse platelets, via the platelet GP
Ib–IX–V complex. Because proteolytically inactive thrombin can
activate wild-type mouse and human platelets after treatment with
thrombin to cleave GP V, this mechanism is involved in thrombin-induced
platelet aggregation. Platelet activation through GP Ib–IX depends on
ADP secretion, and specific inhibitors demonstrate that the recently
cloned P2Y
12
ADP receptor (G
i
-coupled ADP
receptor) is involved in this pathway, and that the P2Y
1
receptor (G
q
-coupled ADP receptor) may play a less
significant role. Thrombosis was generated in GP V null mice only in
response to catalytically inactive thrombin, whereas thrombosis
occurred in both genotypes (wild type and GP V null) in response to
active thrombin. These data support a thrombin receptor function for
the platelet membrane GP Ib–IX–V complex, and describe a novel
thrombin signaling mechanism involving an initiating proteolytic event
followed by stimulation of the GP Ib–IX via thrombin acting as a
ligand, resulting in platelet activation.
A Probit Analysis of Development Control: A Hong Kong Case Study of Residential Zones
Authors: Lai Lawrence W. C. , Ho Winky K. O.
Published: July 2002

This paper uses a probit model to evaluate a total of 1353 sets of cross-sectional development control (planning application) statistics not previously published for 3 classes of statutory residential zones in Hong Kong over a period of 24 years from 1975. As far as the selected zones are concerned, the findings refute the critical view that the Town Planning Board process in Hong Kong generates significant rent-seeking activities in favour of large developers. They also reject the official assertion that the decisions made by the Town Planning Board are independent of exogenous policy influence of government.
Women and Poverty in Morocco: The Many Faces of Social Exclusion
Authors: Skalli Loubna H.
Published: July 2002

This article focuses on the gender dimension of poverty in Morocco. It questions the inadequate parameters relied on in the existing studies on the subject and underlines their blindness to the complex causes and effects of poverty among the female population in the country. The article then approaches female poverty from its multidimensional perspective in order to underline the social, cultural, legal as well as economic aspects and implications of poverty. The final section of the article gives a critical reading of some of the strategies currently adopted to reduce the incidence of poverty in Morocco.
On Selective Consumerism: Egyptian Women and Ethnographic Representations
Authors: Wassef Nadia
Published: July 2002

In the light of postmodern debates in anthropology, ethnography offers anthropologists new ways of representing their objects of study. The politics involved in the production and consumption by feminist scholars and activists of women's representations in the Arab world, and Egypt specifically, provides the starting point of this article. Using an ethnographic text examining manifestations of ‘Islamic Feminism’ in Egypt, I explore problems in addressing the subject of veiling – a continuous favourite among researchers. Grappling with stereotypes, assumptions and pre-interpretations based on what we read before going to the field and the questions we formulate in our minds, I look towards strategies of engagement with research subjects where anthropologists can express their commitments to them. Research ethics and reflexivity offer no formulaic guarantees of better representations, but pave the way towards understanding one's motivations and urges ethnographers to examine the impact of their work, both on the immediate community, and with regard to larger power politics. Given the fluid nature of identities and the relative fixedness of representations, solutions do not appear in abundance. Working outside of unnecessary dichotomies and searching for incongruities presents interesting possibilities for future ethnographic research.
Discursive Desire: Catherine Belsey's Feminism
Authors: Demoor Marysa , Pieters Jürgen
Published: July 2002

This is an account of an interview with one of Britain's foremost literary theorists, Professor Catherine Belsey. The interview was conducted in Ghent, Belgium in 1997. The discussion spans all of Belsey's works, from the earliest, Critical Practice (1980), to her latest publication, Shakespeare and the Loss of Eden (1999). In this piece, Belsey openly and unpretentiously discusses her feminist commitment, her sometimes controversial critical positions, some of the influences on her careers and the importance to her of her teaching.
Citizenship: Towards a Feminist Synthesis
Authors: Lister Ruth
Published: July 2002

A synthesis of rights and participatory approaches to citizenship, linked through the notion of human agency, is proposed as the basis for a feminist theory of citizenship. Such a theory has to address citizenship's exclusionary power in relation to both nation-state ‘outsiders’ and ‘insiders’. With regard to the former, the article argues that a feminist theory and politics of citizenship must embrace an internationalist agenda. With regard to the latter, it offers the concept of a ‘differentiated universalism’ as an attempt to reconcile the universalism which lies at the heart of citizenship with the demands of a politics of difference. Embracing also the reconstruction of the public-private dichotomy, citizenship, reconceptualized in this way, can, it is argued, provide us with an important theoretical and political tool.
Narratives of Irishness and the Problem of Abortion: The X Case 1992
Authors: Smyth Lisa
Published: July 2002

This paper considers the ways in which discourses of abortion and discourses of national identity were constructed and reproduced through the events of the X case in the Republic of Ireland in 1992. This case involved a state injunction against a 14-year-old rape victim and her parents, to prevent them from obtaining an abortion in Britain. By examining the controversy the case gave rise to in the national press, I will argue that the terms of abortion politics in Ireland shifted from arguments based on rights to arguments centred on national identity, through the questions the X case raised about women's citizenship status, and women's position in relation to the nation and the state. Discourses of national identity and discourses of abortion shifted away from entrenched traditional positions, towards more liberal articulations.
Public and Private Citizenship: From Gender Invisibility to Feminist Inclusiveness
Authors: Prokhovnik Raia
Published: July 2002

Conceptions of citizenship which rest on an abstract and universal notion of the individual founder on their inability to recognize the political relevance of gender. Such conceptions, because their ‘gender-neutrality’ has the effect of excluding women, are not helpful to the project of promoting the full citizenship of women.

The question of citizenship is often reduced to either political citizenship, in terms of an instrumental notion of political participation, or social citizenship, in terms of an instrumental notion of economic (in)dependence. The paper argues for the recognition of citizenship as gendered, and as an ethical, that is non-instrumental, social status which is distinct from both political participation and economic (in)dependence. What unites us as citizens, in our equal membership of the political community, need not rely on a conception of us as ‘neutral’ (abstract, universalized, genderless) individuals undertaking one specific activity located in the public realm, but can take account of the diverse ways in which we engage in ethically-grounded activities on the basis of our different genders, ethnic and cultural backgrounds and other differences, in both the public and private realms.

A convincing feminist conception of citizenship necessarily involves a radical redefinition of the public/private distinction to accommodate the recognition of citizenship practices in the private realm. The paper builds on the observation that the concept of ‘citizenship’ is broader than the concept of ‘the political’ (or ‘the social/economic’), and contends that feminism provides us with the emancipatory potential of gendered subjectivity, which applies to both men and women. The recognition of gendered subjectivity opens the way to the recognition of the diversity of citizenship practices.

It is not that women need to be liberated from the private realm, in order to take part in the public realm as equal citizens, but that women – and men – already undertake responsibilities of citizenship in both the public and the private realms.
Cultural Differences in Early Mathematics Learning: A Comparison of Euro-American, Chinese-American, and Taiwan-Chinese Families
Authors: Huntsinger Carol S. , Jose Paul E. , Liaw Fong-Ruey , Ching Wei-Di
Published: July 2002

Forty second-generation Euro-American, and 40 Chinese-American children were drawn from well-educated two-parent families in the suburban Chicago area and 40 Chinese children were drawn from a similar population in Taipei, Taiwan (10 preschool girls, 10 preschool boys, 10 kindergarten girls, and 10 kindergarten boys in each group). Chinese-American and Taiwan-Chinese children outperformed Euro-American children on measures of mathematics, spatial relations, and numeral formation. Chinese-American parents gave more formal, direct mathematics instruction, structured their child’s time to a greater degree, and reported more encouragement for mathematics-related activities than did Euro-American parents. A path analysis using Eccles’ (1993) model of academic motivation showed that ethnicity, parents’ child-specific beliefs, and parents’ work-oriented practices directly predicted mathematics-related outcomes.
Review Article: Glutamate Receptors in Peripheral Tissues: Current Knowledge, Future Research, and Implications for Toxicology
Authors: Gill Santokh S. , Pulido Olga M.
Published: July 2002

We illustrate the specifi c cellular distribution of different subtypes of glutamate receptors (GluRs) in peripheral neural and non-neural tissues. Some of the noteworthy locations are the heart, kidney, lungs, ovary, testis and endocrine cells. In these tissues the GluRs may be important in mediating cardiorespiratory, endocrine and reproductive functions which include hormone regulation, heart rhythm, blood pressure, circulation and reproduction. Since excitotoxicity of excitatory amino acids (EAAs) in the CNS is intimately associated with the GluRs, the toxic effects may be more generalized than initially assumed. Currently there is not enough evidence to suggest the reassessment of the regulated safety levels for these products in food since little is known on how these receptors work in each of these organs. More research is required to assess the extent that these receptors participate in normal functions and/or in the development of diseases and how they mediate the toxic effects of EAAs. Non-neural GluRs may be involved in normal cellular functions such as excitability and cell to cell communication. This is supported by the wide distribution in plants and animals from invertebrates to primates. The important tasks for the future will be to clarify the multiple biological roles of the GluRs in neural and non-neural tissues and identify the conditions under in which these are up- or down-regulated. Then this could provide new therapeutic strategies to target GluRs outside the CNS.
As the First 50 Years of Computing Draw to An End …: What Kind of Society Do We Want?
Authors: Remenyi Dan
Published: July 2002

In the next 5–10 years advances in information technology and telecommunications will continue to impact on all aspects of society. This will lead to a more efficient and perhaps effective way of life, but a price over and above any financial consideration will have to be paid for these developments. The essential question for today is what kind of society do we want to create for ourselves. We have to be particularly aware of the potential for unintentional consequences of the siliconization of our society.
Increments in cytokines and matrix metalloproteinases in skeletal muscle after injection of tissue‐damaging toxins from the venom of the snake Bothrops asper
Authors: Rucavado Alexandra , Escalante Teresa , Teixeira Catarina F. P. , Fernándes Cristina María , Díaz Cecilia , Gutiérrez José María
Published: July 2002

Envenomations by the snake Bothrops asper are characterized by prominent local tissue damage (i.e. myonecrosis), blistering, hemorrhage and edema. Various phospholipases A2 and metalloproteinases that induce local pathological alterations have been purified from this venom. Since these toxins induce a conspicuous inflammatory response, it has been hypothesized that inflammatory mediators may contribute to the local pathological alterations described. This study evaluated the local production of cytokines and matrix metalloproteinases (MMPs) as a consequence of intramuscular injections of an Asp‐49 myotoxic phospholipase A2 (myotoxin III (MT‐III)) and a P‐I type hemorrhagic metalloproteinase (BaP1) isolated from B. asper venom. Both enzymes induced prominent tissue alterations and conspicuous increments in interleukin (IL)‐1β, IL‐6 and a number of MMPs, especially gelatinase MMP‐9, rapidly after injection. In contrast, no increments in tumor necrosis factor‐α (TNF‐α) and interferon‐γ were detected. In agreement, MT‐III and BaP1 did not induce the synthesis of TNF‐α by resident peritoneal macrophages in vitro. Despite the conspicuous expression of latent forms of MMPs in muscle, evidenced by zymography, there were no increments in activated MMP‐2 and only a small increase in activated MMP‐9, as detected by a functional enzymatic assay. This suggests that MMP activity was regulated by a highly controlled activation of latent forms and, probably, by a concomitant synthesis of MMP inhibitors. Since no hemorrhage nor dermonecrosis were observed after injection of MT‐III, despite a prominent increase in MMP expression, and since inflammatory exudate did not enhance hemorrhage induced by BaP1, it is suggested that endogenous MMPs released in the tissue are not responsible for the dermonecrosis and hemorrhage characteristic of B. asper envenomation. Moreover, pretreatment of mice with the peptidomimetic MMP inhibitor batimastat did not reduce myotoxic nor edema‐forming activities of MT‐III, suggesting that MMPs do not play a prominent role in the pathogenesis of these effects in this experimental model. It is concluded that MT‐III and BaP1 induce a local inflammatory response associated with the synthesis of IL‐1β, IL‐6 and MMPs. MMPs do not seem to play a prominent role in the acute local pathological alterations induced by these toxins in this experimental model.
Role of cytokines in myocardial ischemia and reperfusion
Authors: Sharma H. S. , Das D. K.
Published: July 2002

Mediators of myocardial inflammation, predominantly cytokines, have for many years been implicated in the healing processes after infarction. In recent years, however, more attention has been paid to the possibility that the inflammation may result in deleterious complications for myocardial infarction. The proinflammatory cytokines may mediate myocardial dysfunction associated with myocardial infarction, severe congestive heart failure, and sepsis. A growing body of literature suggests that inflammatory mediators could play a crucial role in ischemia–reperfusion injury. Furthermore, ischemia–reperfusion not only results in the local transcriptional and translational upregulation of cytokines but also leads to tissue infiltration by inflammatory cells. These inflammatory cells are a ready source of a variety of cytokines which could be lethal for the cardiomyocytes. At the cellular level it has been shown that hypoxia causes a series of well documented changes in cardiomyocytes that includes loss of contractility, changes in lipid metabolism and subsequent irreversible cell membrane damage leading to cell death. For instance, hypoxic cardiomyocytes produce interleukin‐6 (IL‐6) which could contribute to the myocardial dysfunction observed in ischemia reperfusion injury. Ischemia followed by reperfusion induces a number of other multi‐potent cytokines, such as IL‐1, IL‐8, tumor necrosis factor‐α (TNF‐α), transforming growth factor‐β1 (TGF‐β1) as well as an angiogenic cytokine/ growth factor, vascular endothelial growth factor (VEGF), in the heart. Intrestingly, these multipotent cytokines (e.g. TNF‐α) may induce an adaptive cytoprotective response in the reperfused myocardium. In this review, we have included a number of cytokines that may contribute to ventricular dysfunction and/or to the cytoprotective and adaptive changes in the reperfused heart.
Levels of soluble Fas/APO‐1 in patients with Behçet′s disease
Authors: Hamzaoui K. , Hamzaoui A. , Zakraoui L. , Chabbou A.
Published: July 2002

The aim of this study was to quantify soluble Fas/APO1 (sFas/APO‐1) protein in the serum of patients with Behcet′s disease (BD) in active and inactive stages, compared with patients with systemic lupus erythematosus (SLE) and patients with rheumatoid arthritis (RA). Soluble Fas/APO‐1 was quantified using a sandwich enzyme‐linked immunosorbent assay. Increased serum sFas/APO‐1 levels were observed in active BD, compared with inactive BD, RA patients and SLE patients. Increased serum sFas/APO‐1 levels were correlated with the presence of neurologic manifestations or pulmonary involvement in active BD. In conclusion, increased levels of sFas/APO‐1 occurred frequently and exclusively in active BD patients. Preliminary evidence suggested that elevated levels of sFas/APO‐1 are associated with the clinical stage and clinical manifestations in BD.