bluuebunny/crossref_metadata_2025 huggingface dataset:
Hepatic differentiation induced by oncostatin M attenuates fetal liver hematopoiesis
Authors: Kinoshita Taisei , Sekiguchi Takashi , Xu Ming-jiang , Ito Yoshiaki , Kamiya Akihide , Tsuji Koh-ichiro , Nakahata Tatsutoshi , Miyajima Atsushi
Published: July 2002

Embryonic liver is a transient site for definitive hematopoiesis. Along with maturation of the bone marrow and spleen, hematopoietic cells relocate from the liver to their final destinations while the liver starts organizing its own structure and develops numerous metabolic functions toward adult. Recently, it was demonstrated that the signal exerted by oncostatin M (OSM) through gp130 plays a pivotal role in the maturation process of the liver bothin vitroandin vivo. However, the molecular basis underlying the termination of embryonic hematopoiesis remains unknown. In this study, we report that primary culture of fetal hepatic cells from embryonic day 14.5 murine embryos supported expansion of blood cells from Lin−Sca-1+c-Kit+cells, giving rise to myeloid, lymphoid, and erythroid lineages. Of interest, promotion of hepatic development by OSM and glucocorticoid strongly suppressedin vitrohematopoiesis. Consistent with these results, hepatic culture from the embryonic day 18.5 liver no longer supported hematopoiesis. These data together with the previous observations suggest that the signals exerted by OSM and glucocorticoid induce hepatic differentiation, which in turn terminate embryonic hematopoiesis and promote relocation of hematopoietic cells.
One Lyn molecule is sufficient to initiate phosphorylation of aggregated high-affinity IgE receptors
Authors: Wofsy Carla , Vonakis Becky M. , Metzger Henry , Goldstein Byron
Published: July 2002

In response to antigenic stimuli, the multisubunit immune recognition receptors become aggregated and then phosphorylated on their cytoplasmic tyrosines. For the clonotypic receptors of B and T cells and for Fc receptors such as the high-affinity receptor for IgE (FcɛRI), a Src family kinase initiates this phosphorylation. We ask whether aggregation of the initiating kinase itself is required for signal transduction or whether, alternatively, a single associated kinase molecule can phosphorylate the receptors in an aggregate. We formulate the alternative molecular mechanisms mathematically and compare predictions with experimental findings on FcɛRI-bearing cells expressing varying amounts of the transfected Src family kinase Lyn. The data are consistent with the requirement of only a single Lyn molecule per FcɛRI aggregate to initiate signaling and are inconsistent with a mechanism requiring more than one Lyn molecule.
Activation and adoptive transfer of Epstein–Barr virus-specific cytotoxic T cells in solid organ transplant patients with posttransplant lymphoproliferative disease
Authors: Khanna Rajiv , Bell Scott , Sherritt Martina , Galbraith Andrew , Burrows Scott R. , Rafter Lee , Clarke Belinda , Slaughter Richard , Falk Michael C. , Douglass Jo , Williams Trevor , Elliott Suzanne L. , Moss Denis J.
Published: July 2002

The treatment of Epstein–Barr virus (EBV)-associated lymphoproliferative disease (PTLD) in EBV seronegative solid organ transplant recipients who acquire their EBV infection after engraftment poses a considerable challenge because of underlying immunosuppression that inhibits the virus-specific cytotoxic T cell (CTL) responsein vivo. We have developed a protocol for activating autologous EBV-specific CTL lines from these patients and show their potential use for immunotherapy against PTLD in solid organ transplant patients. Peripheral blood mononuclear cells from a panel of solid organ transplant recipients with and without active PTLD were used to assess EBV-specific memory CTL responses. The activation protocol involved cocultivation of peripheral blood mononuclear cells with an autologous lymphoblastoid cell line under conditions that favored expansion of virus-specific CTL and hindered the proliferation of allospecific T cells. These CTL consistently showed (i) strong EBV-specificity, including reactivity through defined epitopes in spite of concurrent immunosuppressive therapy, and (ii) no alloreactivity toward donor alloantigens. More importantly, adoptive transfer of these autologous CTLs into a single patient with active PTLD was coincident with a very significant regression of the PTLD. These results demonstrate that a potent EBV-specific memory response can be expanded from solid organ recipients who have acquired their primary EBV infection under high levels of immunosuppressive therapy and that these T cells may have therapeutic potential against PTLD.
A homeobox gene,
vax2
, controls the patterning of the eye dorsoventral axis
Authors: Barbieri Anna Maria , Lupo Giuseppe , Bulfone Alessandro , Andreazzoli Massimiliano , Mariani Margherita , Fougerousse Francoise , Consalez Gian Giacomo , Borsani Giuseppe , Beckmann Jacques S. , Barsacchi Giuseppina , Ballabio Andrea , Banfi Sandro
Published: July 2002

We have identified a transcription factor specifically expressed in the developing vertebrate eye. We named this gene
vax2
because of the high degree of sequence similarity to the recently described
vax1
. Both in the human and mouse genomes,
vax2
is localized in the vicinity of the
emx1
gene. This mapping assignment, together with the previously reported colocalization of
Vax1
and
Emx2
in mouse, indicates that the
vax
and the
emx
genes may be organized in clusters.
vax2
has a remarkable expression domain confined to the ventral portion of the prospective neural retina in mouse, human, and
Xenopus
. The overexpression of either the frog
Xvax2
or the human
VAX2
in
Xenopus
embryos leads to an aberrant eye phenotype and, in particular, determines a ventralizing effect on the developing eye. The expression domain of the transcription factor
Xpax2
, normally confined to the ventral developing retina, extends to the dorsal region of the retina after overexpression of
vax2
. On the other hand, the expression of
Xvent2
, a molecular marker of the dorsal retina, is strongly reduced. Furthermore,
vax2
overexpression induces a striking expansion of the optic stalk, a structure deriving from the ventralmost region of the eye vesicle. Altogether, these data indicate that
vax2
plays a crucial role in eye development and, in particular, in the specification of the ventral optic vesicle.
Tubulointerstitial nephritis antigen: An extracellular matrix protein that selectively regulates tubulogenesis vs. glomerulogenesis during mammalian renal development
Authors: Kanwar Yashpal S. , Kumar Anil , Yang Qiwei , Tian Yufeng , Wada Jun , Kashihara Naoki , Wallner Elisabeth I.
Published: July 2002

Tubulointerstitial nephritis antigen (TIN-ag) is an extracellular matrix protein and is expressed in the renal tubular basement membranes. Its role in metanephric development was investigated. TIN-ag cDNA, isolated from the newborn mouse library, had an ORF of 1,425 nucleotides, a putative signal sequence, and an ATP/GTP-binding site. The translated sequence had ≈80% identity with rabbit TIN-ag. Among various tissues, TIN-ag mRNA was primarily expressed in the newborn kidney. In the embryonic metanephros, TIN-ag expression was confined to the distal convolution or pole of the S-shaped body, the segment of the nascent nephron that is the progenitor of renal tubules. Treatment with TIN-ag antisense oligodeoxynucleotide induced dysmorphogenesis of the embryonic metanephroi, malformation of the S-shaped body, and a decrease in the tubular population, whereas the glomeruli were unaffected. Treatment also led to a decrease of TIN-Ag mRNA,
de novo
synthesis of TIN-ag protein, and its antibody reactivity. The mRNA expression of glomerular epithelial protein 1 (a marker for renal podocytes), anti-heparan-sulfate-proteoglycan antibody reactivity, and wheat germ agglutinin lectin staining of the metanephros were unaffected. The anti-TIN-ag antibody treatment also caused deformation of the S-shaped body and a reduction in the tubular population, whereas the glomeruli were unchanged. The data suggest that the TIN-ag, unlike other basement membrane proteins, selectively regulates tubulogenesis, whereas glomerulogenesis is largely unaffected.
Differential effect of an Ig μ transgene on development of pre-B cells in fetal and adult SCID mice
Authors: Bosma Gayle C. , Chang Yung , Karasuyama Hajime , Bosma Melvin J.
Published: July 2002

Progression of pro-B lymphocytes to the pre-B stage depends on the expression of a pre-B cell receptor (pre-BCR), consisting of an Ig μ H chain, Ig surrogate light chain, and associated signal transducing chains. Mice that are unable to express a pre-BCR show an arrest of B cell development at the pro-B stage. Such is the case for severe combined immune deficient (SCID) mice in which μ chains are not made because of a defect in V(D)J recombination. When μ chains are made, as in SCID mice bearing a functional μ transgene, then B cell differentiation can proceed to the pre-B stage. However, as reported here, a μ transgene (M54) that promotes development of SCID pre-B cells in adult bone marrow fails to do so in fetal liver. We suggest that a pre-BCR containing the M54 μ chain cannot signal progression of pro-B cells to the pre-B stage in the fetal liver microenvironment.
Productive infection of double-negative T cells with HIVin vivo
Authors: Marodon Gilles , Warren David , Filomio Michael C. , Posnett David N.
Published: July 2002

HIV induces CD4 down-regulation from the surface of infected cells by several independent mechanisms, suggesting an important biological role for this phenomenon.In vitroCD4 down-regulation generates T cells with a double-negative (DN) CD4−CD8−T cell receptor-αβ+phenotype. However, evidence that this down-regulation occursin vivoin HIV-infected subjects is lacking, and viral load or viral production assays invariably focus on CD4+T cells. We show here that HIV infection can often be detected in sorted DN cells from peripheral blood and lymph nodes, even when plasma viral load is undetectable. DN T cells infected with HIV represented up to 20% of the cellular viral load in T cells, as determined by DNA PCR. In patients on successful highly active antiretroviral therapy, the viral load decreased in the plasma in CD4+and in DN T cells, suggesting that infected DN cells, like CD4+cells, contribute to viral production and are sensitive to highly active antiretroviral therapy. Indeed, HIV unspliced and multispliced RNAs were often detectable in DN T cells in spite of the small size of this subset. Infectious virus from DN T cells was transmitted efficiently in coculture experiments with uninfected T cell lymphoblasts, even when viral DNA in the DN cells was barely detectable. We conclude that a discrete population of infected DN T cells exists in HIV-positive subjects, even when the plasma viral load is undetectable. These cells may represent an important source of infectious virus.
An optimal Mg
2+
concentration for kinetic folding of the
Tetrahymena
ribozyme
Authors: Rook Martha S. , Treiber Daniel K. , Williamson James R.
Published: July 2002

Divalent metal ions, such as Mg
2+
, are generally required for tertiary structure formation in RNA. Although the role of Mg
2+
binding in RNA-folding equilibria has been studied extensively, little is known about the role of Mg
2+
in RNA-folding kinetics. In this paper, we explore the effect of Mg
2+
on the rate-limiting step in the kinetic folding pathway of the
Tetrahymen
a ribozyme. Analysis of these data reveals the presence of a Mg
2+
-stabilized kinetic trap that slows folding at higher Mg
2+
concentrations. Thus, the
Tetrahymena
ribozyme folds with an optimal rate at 2 mM Mg
2+
, just above the concentration required for stable structure formation. These results suggest that thermodynamic and kinetic folding of RNA are cooptimized at a Mg
2+
concentration that is sufficient to stabilize the folded form but low enough to avoid kinetic traps and misfolding.
Optical images of visible and invisible percepts in the primary visual cortex of primates
Authors: Macknik Stephen L. , Haglund Michael M.
Published: July 2002

We optically imaged a visual masking illusion in primary visual cortex (area V-1) of rhesus monkeys to ask whether activity in the early visual system more closely reflects the physical stimulus or the generated percept. Visual illusions can be a powerful way to address this question because they have the benefit of dissociating the stimulus from perception. We used an illusion in which a flickering target (a bar oriented in visual space) is rendered invisible by two counter-phase flickering bars, called masks, which flank and abut the target. The target and masks, when shown separately, each generated correlated activity on the surface of the cortex. During the illusory condition, however, optical signals generated in the cortex by the target disappeared although the image of the masks persisted. The optical image thus was correlated with perception but not with the physical stimulus.
Nuclear foci of mammalian recombination proteins are located at single-stranded DNA regions formed after DNA damage
Authors: Raderschall Elke , Golub Efim I. , Haaf Thomas
Published: July 2002

A sensitive and rapid
in situ
method was developed to visualize sites of single-stranded (ss) DNA in cultured cells and in experimental test animals. Anti-bromodeoxyuridine antibody recognizes the halogenated base analog incorporated into chromosomal DNA only when substituted DNA is in the single strand form. After treatment of cells with DNA-damaging agents or γ irradiation, ssDNA molecules form nuclear foci in a dose-dependent manner within 60 min. The mammalian recombination protein Rad51 and the replication protein A then accumulate at sites of ssDNA and form foci, suggesting that these are sites of recombinational DNA repair.
Structure and function in rhodopsin: Further elucidation of the role of the intradiscal cysteines, Cys-110, -185, and -187, in rhodopsin folding and function
Authors: Hwa John , Reeves Philip J. , Klein-Seetharaman Judith , Davidson Florence , Khorana H. Gobind
Published: July 2002

The disulfide bond between Cys-110 and Cys-187 in the intradiscal domain is required for correct folding
in vivo
and function of mammalian rhodopsin. Misfolding in rhodopsin, characterized by the loss of ability to bind 11-
cis-
retinal, has been shown to be caused by an intradiscal disulfide bond different from the above native disulfide bond. Further, naturally occurring single mutations of the intradiscal cysteines (C110F, C110Y, and C187Y) are associated with retinitis pigmentosa (RP). To elucidate further the role of every one of the three intradiscal cysteines, mutants containing single-cysteine replacements by alanine residues and the above three RP mutants have been studied. We find that C110A, C110F, and C110Y all form a disulfide bond between C185 and C187 and cause loss of retinal binding. C185A allows the formation of a C110–C187 disulfide bond, with wild-type-like rhodopsin phenotype. C187A forms a disulfide bond between C110 and C185 and binds retinal, and the pigment formed has markedly altered bleaching behavior. However, the opsin from the RP mutant C187Y forms no rhodopsin chromophore.
Exposure of cryptic epitopes on transthyretin only in amyloid and in amyloidogenic mutants
Authors: Goldsteins Gundars , Persson Håkan , Andersson Karin , Olofsson Anders , Dacklin Ingrid , Edvinsson Åsa , Saraiva Maria João , Lundgren Erik
Published: July 2002

The structural requirements for generation of amyloid from the plasma protein transthyretin (TTR) are not known, although it is assumed that TTR is partly misfolded in amyloid. In a search for structural determinants important for amyloid formation, we generated a TTR mutant with high potential to form amyloid. We demonstrated that the mutant represents an intermediate in a series of conformational changes leading to amyloid. Two monoclonal antibodies were generated against this mutant; each displayed affinity to
ex vivo
TTR and TTR mutants with amyloidogenic folding but not to wild-type TTR or mutants exhibiting the wild-type fold. Two cryptic epitopes were mapped to a domain of TTR, where most mutations associated with amyloidosis occur and which we propose is displaced at the initial phase of amyloid formation, opening up new surfaces necessary for autoaggregation of TTR monomers. The results provide direct biochemical evidence for structural changes in an amyloidogenic intermediate of TTR.
New insights into tumor suppression: PTEN suppresses tumor formation by restraining the phosphoinositide 3-kinase/AKT pathway
Authors: Cantley Lewis C. , Neel Benjamin G.
Published: July 2002

The most recently discovered
PTEN
tumor suppressor gene
has been found to be defective in a large number of human cancers. In
addition, germ-line mutations in
PTEN
result in the
dominantly inherited disease Cowden syndrome, which is characterized by
multiple hamartomas and a high proclivity for developing cancer. A
series of publications over the past year now suggest a mechanism by
which PTEN loss of function results in tumors. PTEN appears to
negatively control the phosphoinositide 3-kinase signaling pathway for
regulation of cell growth and survival by dephosphorylating the 3
position of phosphoinositides.
A mouse model for achondroplasia produced by targeting fibroblast growth factor receptor 3
Authors: Wang Yingcai , Spatz Michal K. , Kannan Karuppiah , Hayk Hovhannisyan , Avivi Aaron , Gorivodsky Marat , Pines Mark , Yayon Avner , Lonai Peter , Givol David
Published: July 2002

Achondroplasia, the most common form of dwarfism in man, is a dominant genetic disorder caused by a point mutation (G380R) in the transmembrane region of fibroblast growth factor receptor 3 (FGFR3). We used gene targeting to introduce the human achondroplasia mutation into the murine FGFR3 gene. Heterozygotes for this point mutation that carried the
neo
cassette were normal whereas
neo
+
homozygotes had a phenotype similar to FGFR3-deficient mice, exhibiting bone overgrowth. This was because of interference with mRNA processing in the presence of the
neo
cassette. Removal of the
neo
selection marker by Cre/loxP recombination yielded a dominant dwarf phenotype. These mice are distinguished by their small size, shortened craniofacial area, hypoplasia of the midface with protruding incisors, distorted brain case with anteriorly shifted foramen magnum, kyphosis, and narrowed and distorted growth plates in the long bones, vertebrae, and ribs. These experiments demonstrate that achondroplasia results from a gain-of-FGFR3-function leading to inhibition of chondrocyte proliferation. These achondroplastic dwarf mice represent a reliable and useful model for developing drugs for potential treatment of the human disease.
Embryonic stem cells differentiate into oligodendrocytes and myelinate in culture and after spinal cord transplantation
Authors: Liu Su , Qu Yun , Stewart Todd J. , Howard Michael J. , Chakrabortty Shushovan , Holekamp Terrence F. , McDonald John W.
Published: July 2002

Demyelination contributes to the loss of function consequent to central nervous system (CNS) injury. Enhanced remyelination through transplantation of myelin-producing cells may offer a pragmatic approach to restoring meaningful neurological function. An unlimited source of cells suitable for such transplantation therapy can be derived from embryonic stem (ES) cells, which are both pluripotent and genetically flexible. In this paper we show that oligodendrocyte cultures can be reliably produced from retinoic acid-induced ES cells and that these oligodendrocytes can myelinate axons
in vitro
. Methods were further developed for generating highly enriched cultures of oligodendrocytes through an additional culturing step, producing an intermediate “oligosphere” stage. To test whether ES cells can survive, migrate, and differentiate into mature myelin-producing cells in areas of demyelination in the adult CNS, ES cells were transplanted into the dorsal columns of adult rat spinal cord 3 days after chemical demyelination. In the demyelination site, large numbers of ES cells survived and differentiated primarily into mature oligodendrocytes that were capable of myelinating axons. Furthermore, when oligosphere cells were transplanted into the spinal cords of myelin-deficient
shiverer
(
shi/shi
) mutant mice, the ES cell-derived oligodendrocytes migrated into the host tissue, produced myelin and myelinated host axons. These studies demonstrate the ability of ES cell-derived oligodendrocytes to myelinate axons in culture and to replace lost myelin in the injured adult CNS. Transplantation of ES cells may be a practical approach to treatment of primary and secondary demyelinating diseases in the adult CNS.
Highly mutagenic replication by DNA polymerase V (UmuC) provides a mechanistic basis for SOS untargeted mutagenesis
Authors: Maor-Shoshani Ayelet , Reuven Nina Bacher , Tomer Guy , Livneh Zvi
Published: July 2002

When challenged by DNA-damaging agents,
Escherichia coli
cells respond by inducing the SOS stress response, which leads to an increase in mutation frequency by two mechanisms: translesion replication, a process that causes mutations because of misinsertion opposite the lesions, and an inducible mutator activity, which acts at undamaged sites. Here we report that DNA polymerase V (pol V; UmuC), which previously has been shown to be a lesion-bypass DNA polymerase, was highly mutagenic during
in vitro
gap-filling replication of a gapped plasmid carrying the
cro
reporter gene. This reaction required, in addition to pol V, UmuD′, RecA, and single-stranded DNA (ssDNA)-binding protein. pol V produced point mutations at a frequency of 2.1 × 10
−4
per nucleotide (2.1% per
cro
gene), 41-fold higher than DNA polymerase III holoenzyme. The mutational spectrum of pol V was dominated by transversions (53%), which were formed at a frequency of 1.3 × 10
−4
per nucleotide (1.1% per
cro
gene), 74-fold higher than with pol III holoenzyme. The prevalence of transversions and the protein requirements of this system are similar to those of
in vivo
untargeted mutagenesis (SOS mutator activity). This finding suggests that replication by pol V, in the presence of UmuD′, RecA, and ssDNA-binding protein, is the basis of chromosomal SOS untargeted mutagenesis.
The hermaphrodite sperm/oocyte switch requires the
Caenorhabditis elegans
homologs of PRP2 and PRP22
Authors: Puoti Alessandro , Kimble Judith
Published: July 2002

Sex determination in the hermaphrodite germ line of
Caenorhabditis elegans
is controlled posttranscriptionally. The switch from spermatogenesis to oogenesis relies on regulation of the
fem-3
sex-determining gene via a regulatory element in the
fem-3
3′ untranslated region. Previous work showed that at least six
mog
genes are required for repression by the
fem-3
3′ untranslated region, and that one of those genes,
mog-1
, encodes a DEAH-box protein. In this paper, we report the cloning of
mog-4
and
mog-5
and the finding that
mog-4
and
mog-5
also encode DEAH-box proteins. Our molecular identification of
mog-4
and
mog-5
relied on genetic mapping and transformation rescue and was confirmed by a missense mutation in each gene. A phylogenetic analysis revealed that the
C. elegans
MOG-1, MOG-4, and MOG-5 proteins are closely related to the yeast proteins PRP16, PRP2, and PRP22, respectively. In view of their effect on
fem-3
regulation and their homology to PRP16, PRP2, and PRP22, we propose that MOG-1, MOG-4, and MOG-5 are required for posttranscriptional regulation, perhaps by modifying the conformation of ribonucleoprotein complexes.
A stimulus-specific role for CREB-binding protein (CBP) in T cell receptor-activated tumor necrosis factor α gene expression
Authors: Falvo James V. , Brinkman Brigitta M. N. , Tsytsykova Alla V. , Tsai Eunice Y. , Yao Tso-Pang , Kung Andrew L. , Goldfeld Anne E.
Published: July 2002

The cAMP response element binding protein (CREB)-binding protein (CBP)/p300 family of coactivator proteins regulates gene transcription through the integration of multiple signal transduction pathways. Here, we show that induction of tumor necrosis factor α (TNF-α) gene expression in T cells stimulated by engagement of the T cell receptor (TCR) or by virus infection requires CBP/p300. Strikingly, in mice lacking one copy of the CBP gene, TNF-α gene induction by TCR activation is inhibited, whereas virus induction of the TNF-α gene is not affected. Consistent with these findings, the transcriptional activity of CBP is strongly potentiated by TCR activation but not by virus infection of T cells. Thus, CBP gene dosage and transcriptional activity are critical in TCR-dependent TNF-α gene expression, demonstrating a stimulus-specific requirement for CBP in the regulation of a specific gene.
The
Escherichia coli
signal transducers PII (GlnB) and GlnK form heterotrimers
in vivo
: Fine tuning the nitrogen signal cascade
Authors: van Heeswijk Wally C. , Wen Daying , Clancy Paula , Jaggi Rene , Ollis David L. , Westerhoff Hans V. , Vasudevan Subhash G.
Published: July 2002

The PII protein is
Escherichia coli
's cognate transducer of the nitrogen signal to the NRII (NtrB)/NRI (NtrC) two-component system and to adenylyltransferase. Through these two routes, PII regulates both amount and activity of glutamine synthetase. GlnK is the recently discovered paralogue of PII, with a similar trimeric x-ray structure. Here we show that PII and GlnK form heterotrimers, in
E. coli
grown in nitrogen-poor medium.
In vitro
, fully uridylylated heterotrimers of the two proteins stimulated the deadenylylation activity of adenylyltransferase, albeit to a lower extent than homotrimeric PII-UMP. Fully uridylylated GlnK did not stimulate, or hardly stimulated, the deadenylylation activity. We propose that uridylylated PII/GlnK heterotrimers fine-regulate the activation of glutamine synthetase. The PII/GlnK couple is a first example of prokaryotic signal transducer that can form heterotrimers. Advantages of hetero-oligomer formation as molecular mechanism for fine-regulation of signal transduction are discussed.
La relation entre les conflits conjugaux, la satisfaction conjugale des mères et la qualité de la communication mère‐adolescente
Authors: Dubé Monique , Julien Danielle , Bouthillier Donald , Lebeau Élise , Bélanger Isabelle , Hamelin Manon
Published: July 2002

Un échantillon composé de 41 couples et leur adolescente participent à une étude sur l'association entre les conflits conjugaux et la communication mère‐fille. Des mesures observationnelles et des questionnaires évaluent le niveau de la qualité de la communication dans le couple, la satisfaction conjugale des parents et la qualité de la communication mère‐adolescente. Les résultats montrent que (a) les conflits observés chez les parents sont associés de façon positive au niveau de confrontation observé entre la mère et la fille et (b) la satisfaction conjugale des mères joue un rôle médiateur entre les conflits dans le couple et le niveau de confrontation mère‐fille. La satisfaction conjugale des mères serait une courroie de transmission dans le processus de propagation des affects et des comportements négatifs du couple à la relation mère‐adolescente.
Cannabis use in relation to illicit drug use and health problems among opiate misusers in treatment
Authors: BEST DAVID , GOSSOP MICHAEL , GREENWOOD JUDY , MARSDEN JOHN , LEHMANN PETRA , STRANG JOHN
Published: July 2002

The study investigated cannabis use among 200 opiate misusers attending out‐patient treatment services at two sites. Three groups were classified according to the frequency of their cannabis use in the previous month; 40.5% were non‐users, 40% daily users and the remaining 19.5% were classified as occasional users (they had used on between 1 and 29 days in the previous month). Non‐users of cannabis had used heroin in the previous month on more occasions than either daily or occasional users (p < 0.001). Non‐cannabis users also reported the highest average frequencies of use of alcohol (p < 0.01) and crack cocaine (p < 0.05). In contrast, daily users of cannabis reported more symptoms of anxiety (p < 0.01) and depression (p < 0.01) than either of the other groups. Finally, daily cannabis users were more likely to report dietary problems than either occasional users or non‐users of cannabis. While cannabis use is highly prevalent among opiate misusers in treatment, its relationship to treatment outcome is complex and requires greater research scrutiny.
Francis Wayland's 1830s Textbooks: Evangelical Ethics and Political Economy
Authors: Frey Donald E.
Published: July 2002

Francis Wayland (1796–1865) became the president of Brown University at age 31, remaining so for twenty-eight years. According to the custom of that era, the president taught moral philosophy and political economy to the Brown undergraduates. Wayland published his lectures on moral philosophy as a textbook in 1835 (this essay cites the 1837 edition); his notes on political economy followed in 1837 (this essay cites the 1841 edition). The Elements of Moral Science ultimately reached 100,000 copies in print, while The Elements of Political Economy reached approximately 50,000 copies and its abridgment another 12,000 (Wayland and Wayland 1868, p. 389). Paul T. Heyne (1982, p. 126) states that Wayland's Political Economy “was by far the most popular political economy texbook prior to the Civil War,” with ongoing influence “through adaptations and imitations.” A comparison of book sales to college enrollments suggests that Wayland's Political Economy served a greater proportion of the market of its day than Paul Samuelson's Economics did between 1948–1980.
The Use of Intravenous Buprenorphine for the Treatment of Opioid Withdrawal in Medically Ill Hospitalized Patients
Authors: Welsh Christopher J. , Suman Meenakshi , Cohen Art , Broyles Lauren , Bennett Melanie , Weintraub Eric
Published: July 2002

The aim of this study was to assess the safety of buprenorphine administered intravenously for the treatment of opioid withdrawal in medically ill hospitalized patients. Data regarding demographic information, number of doses of buprenorphine, and measures of buprenorphine's effects were collected via chart reviews for 30 heroin‐dependent patients who received buprenorphine intravenously during their hospitalization for an acute medical problem. No respiratory depression was observed, and no patients reported feeling “high.” All patients reported that buprenorphine decreased withdrawal symptoms. Thus, intravenous administration of buprenorphine appears to be safe for the treatment of opioid withdrawal.
Who Starts Treatment: Engagement in the NIDA Collaborative Cocaine Treatment Study
Authors: Siqueland Lynne , Crits‐Christoph Paul , Gallop Bob , Gastfriend David , Lis Judy , Frank Arlene , Griffin Margaret , Blaine Jack , Luborsky Lester
Published: July 2002

This study addressed the role of demographic variables, severity of drug dependence, and drug‐related problems in facilitating or impeding engagement into a research treatment. Patients were tracked through various stages of entry for the research treatment: phone screening, intake, and randomization to treatment. Results suggested that certain demographic factors put patients more at risk for dropping out at intake and randomization. African‐American and unemployed patients were less likely to stay in treatment at both stages, with largest differences at intake. Younger patients were less likely to complete both phases, with bigger differences noted at randomization. Patients with more days of cocaine use and patients referred from advertisements were less likely to keep their intake appointments.
Global epidemiology of areca nut usage
Authors: Gupta P. C. , Warnakulasuriya S.
Published: July 2002

Abstract A substantial proportion of the world's population is engaged in chewing areca nut and the habit is endemic throughout the Indian subcontinent, large parts of south Asia and Melanesia. A large variety of ingredients, including tobacco, may be used along with areca nut constituting a betel quid. The composition and method of chewing can vary widely from country to country and these population variations are described in this review. Some populations are known to use areca nut without tobacco providing good opportunities to further research the carcinogenecity of areca nut. Some interesting trends on chewing patterns have emerged from recent data, suggesting a decline in the habit in some countries such as Thailand while the prevalence of areca nut use is rising in India and Taiwan.
Anthropological perspectives on use of the areca nut
Authors: Strickland S. S.
Published: July 2002

Abstract This paper first reviews the identity of historical and contemporary users of the areca nut. It then considers the reasons given by users for indulging in areca consumption, drawing upon historical, ethnographic and experimental sources of evidence for the effects which users have sought to derive from it. Particularly important is the social context in which consumption occurs, and the social meanings attached to areca use and exchange. Finally, a possible evolutionary hypothesis is postulated to explain the origins of areca use as a form of behaviour indicating reproductive availability. However, diverse culturally explicit reasons underlie usage and what may once have been a sufficient rationale for consumption may no longer justify this pattern of behaviour.
Effect of low doses of ethanol on spontaneous locomotor activity in UChB and UChA rats
Authors: QUINTANILLA MARIA ELENA
Published: July 2002

The effects of low to moderate doses of ethanol on spontaneous locomotor activity were studied in the selectively bred high‐ethanol drinking (UChB) and the low‐ethanol drinking (UChA) strain of rats. Alcohol‐naive rats had food and water available ad libitum, although food was removed 24 hours before and during activity testing. After an injection of c.15 M NaCl or ethanol (0.25–1.0 g/kg), spontaneous locomotor activity was monitored every 5 minutes for 20 minutes in an open field apparatus. The UChB rats exhibited increased locomotor activity after doses of 0.25 and 0.50 g/kg of ethanol, while UChA rats failed to show increased locomotor activity at any ethanol dose. Moreover, the UChA rats appeared to be more sensitive to the sedating effects of 1.0 g/kg of ethanol than the UChB rats. These differences were not the result of different brain‐blood alcohol levels. Ethanol intakes by the UChB and UChA rats determined at the conclusion of activity testing averaged 5.0 ± 0.5 and 1.9 ± 0.4 g/kg/day, respectively. The data suggest that ethanol‐induced locomotor stimulation may be associated with ethanol preference and that hyperactivity may be an expression of the positive reinforcing effect of ethanol in UChB rats.
Disrupted Proteolipid Protein Trafficking Results in Oligodendrocyte Apoptosis in an Animal Model of Pelizaeus-Merzbacher Disease
Authors: Gow Alexander , Southwood Cherie M. , Lazzarini Robert A.
Published: July 2002

Abstract. Pelizaeus-Merzbacher disease (PMD) is a dysmyelinating disease resulting from mutations, deletions, or duplications of the proteolipid protein (PLP) gene. Distinguishing features of PMD include pleiotropy and a range of disease severities among patients. Previously, we demonstrated that, when expressed in transfected fibroblasts, many naturally occurring mutant PLP alleles encode proteins that accumulate in the endoplasmic reticulum and are not transported to the cell surface. In the present communication, we show that oligodendrocytes in an animal model of PMD, the msd mouse, accumulate Plp gene products in the perinuclear region and are unable to transport them to the cell surface. Another important aspect of disease in msd mice is oligodendrocyte cell death, which is increased by two- to threefold. We demonstrate in msd mice that this death occurs by apoptosis and show that at the time oligodendrocytes die, they have differentiated, extended processes that frequently contact axons and are expressing myelin structural proteins. Finally, we define a hypothesis that accounts for pathogenesis in most PMD patients and animal models of this disease and, moreover, can be used to develop potential therapeutic strategies for ameliorating the disease phenotype.
A Role for Cdc42 in Macrophage Chemotaxis
Authors: Allen William E. , Zicha Daniel , Ridley Anne J. , Jones Gareth E.
Published: July 2002

Three members of the Rho family, Cdc42, Rac, and Rho are known to regulate the organization of actin-based cytoskeletal structures. In Bac1.2F5 macrophages, we have shown that Rho regulates cell contraction, whereas Rac and Cdc42 regulate the formation of lamellipodia and filopodia, respectively. We have now tested the roles of Cdc42, Rac, and Rho in colony stimulating factor-1 (CSF-1)–induced macrophage migration and chemotaxis using the Dunn chemotaxis chamber. Microinjection of constitutively activated RhoA, Rac1, or Cdc42 inhibited cell migration, presumably because the cells were unable to polarize significantly in response to CSF-1. Both Rho and Rac were required for CSF-1–induced migration, since migration speed was reduced to background levels in cells injected with C3 transferase, an inhibitor of Rho, or with the dominant-negative Rac mutant, N17Rac1. In contrast, cells injected with the dominant-negative Cdc42 mutant, N17Cdc42, were able to migrate but did not polarize in the direction of the gradient, and chemotaxis towards CSF-1 was abolished.

We conclude that Rho and Rac are required for the process of cell migration, whereas Cdc42 is required for cells to respond to a gradient of CSF-1 but is not essential for cell locomotion.
Alf1p, a CLIP-170 Domain-containing Protein, Is Functionally and Physically Associated with α-Tubulin
Authors: Feierbach Becket , Nogales Eva , Downing Kenneth H. , Stearns Tim
Published: July 2002

Tubulin is a heterodimer of α- and β-tubulin polypeptides. Assembly of the tubulin heterodimer in vitro requires the CCT chaperonin complex, and a set of five proteins referred to as the tubulin cofactors (Tian, F., Y. Huang, H. Rommelaere, J. Vandekerckhove, C. Ampe, and N.J. Cowan. 1996. Cell. 86:287–296; Tian, G., S.A. Lewis, B. Feierbach, T. Stearns, H. Rommelaere, C. Ampe, and N.J. Cowan. 1997. J. Cell Biol. 138:821–832). We report the characterization of Alf1p, the yeast ortholog of mammalian cofactor B. Alf1p interacts with α-tubulin in both two-hybrid and immunoprecipitation assays. Alf1p and cofactor B contain a single CLIP-170 domain, which is found in several microtubule-associated proteins. Mutation of the CLIP-170 domain in Alf1p disrupts the interaction with α-tubulin. Mutations in α-tubulin that disrupt the interaction with Alf1p map to a domain on the cytoplasmic face of α-tubulin; this domain is distinct from the region of interaction between α-tubulin and β-tubulin. Alf1p-green fluorescent protein (GFP) is able to associate with microtubules in vivo, and this localization is abolished either by mutation of the CLIP-170 domain in Alf1p, or by mutation of the Alf1p-binding domain in α-tubulin. Analysis of double mutants constructed between null alleles of ALF1 and PAC2, which encodes the other yeast α-tubulin cofactor, suggests that Alf1p and Pac2p act in the same pathway leading to functional α-tubulin. The phenotype of overexpression of ALF1 suggests that Alf1p can act to sequester α-tubulin from interaction with β-tubulin, raising the possibility that it plays a regulatory role in the formation of the tubulin heterodimer.
An Automatic Braking System That Stabilizes Leukocyte Rolling by an Increase in Selectin Bond Number with Shear
Authors: Chen Shuqi , Springer Timothy A.
Published: July 2002

Wall shear stress in postcapillary venules varies widely within and between tissues and in response to inflammation and exercise. However, the speed at which leukocytes roll in vivo has been shown to be almost constant within a wide range of wall shear stress, i.e., force on the cell. Similarly, rolling velocities on purified selectins and their ligands in vitro tend to plateau. This may be important to enable rolling leukocytes to be exposed uniformly to activating stimuli on endothelium, independent of local hemodynamic conditions. Wall shear stress increases the rate of dissociation of individual selectin–ligand tether bonds exponentially (1, 4) thereby destabilizing rolling. We find that this is compensated by a shear-dependent increase in the number of bonds per rolling step. We also find an increase in the number of microvillous tethers to the substrate. This explains (a) the lack of firm adhesion through selectins at low shear stress or high ligand density, and (b) the stability of rolling on selectins to wide variation in wall shear stress and ligand density, in contrast to rolling on antibodies (14). Furthermore, our data successfully predict the threshold wall shear stress below which rolling does not occur. This is a special case of the more general regulation by shear of the number of bonds, in which the number of bonds falls below one.
Nuclear Import of Cdk/Cyclin Complexes: Identification of Distinct Mechanisms for Import of Cdk2/Cyclin E and Cdc2/Cyclin B1
Authors: Moore Jonathan D. , Yang Jing , Truant Ray , Kornbluth Sally
Published: July 2002

Reversible phosphorylation of nuclear proteins is required for both DNA replication and entry into mitosis. Consequently, most cyclin-dependent kinase (Cdk)/cyclin complexes are localized to the nucleus when active. Although our understanding of nuclear transport processes has been greatly enhanced by the recent identification of nuclear targeting sequences and soluble nuclear import factors with which they interact, the mechanisms used to target Cdk/cyclin complexes to the nucleus remain obscure; this is in part because these proteins lack obvious nuclear localization sequences. To elucidate the molecular mechanisms responsible for Cdk/cyclin transport, we examined nuclear import of fluorescent Cdk2/cyclin E and Cdc2/cyclin B1 complexes in digitonin-permeabilized mammalian cells and also examined potential physical interactions between these Cdks, cyclins, and soluble import factors. We found that the nuclear import machinery recognizes these Cdk/cyclin complexes through direct interactions with the cyclin component. Surprisingly, cyclins E and B1 are imported into nuclei via distinct mechanisms. Cyclin E behaves like a classical basic nuclear localization sequence–containing protein, binding to the α adaptor subunit of the importin-α/β heterodimer. In contrast, cyclin B1 is imported via a direct interaction with a site in the NH2 terminus of importin-β that is distinct from that used to bind importin-α.
Induction of Integral Membrane PAM Expression in AtT-20 Cells Alters the Storage and Trafficking of POMC and PC1
Authors: Ciccotosto Giuseppe D. , Schiller Martin R. , Eipper Betty A. , Mains Richard E.
Published: July 2002

Peptidylglycine α-amidating monooxygenase (PAM) is an essential enzyme that catalyzes the COOH-terminal amidation of many neuroendocrine peptides. The bifunctional PAM protein contains an NH2-terminal monooxygenase (PHM) domain followed by a lyase (PAL) domain and a transmembrane domain. The cytosolic tail of PAM interacts with proteins that can affect cytoskeletal organization. A reverse tetracycline-regulated inducible expression system was used to construct an AtT-20 corticotrope cell line capable of inducible PAM-1 expression. Upon induction, cells displayed a time- and dose-dependent increase in enzyme activity, PAM mRNA, and protein. Induction of increased PAM-1 expression produced graded changes in PAM-1 metabolism. Increased expression of PAM-1 also caused decreased immunofluorescent staining for ACTH, a product of proopiomelanocortin (POMC), and prohormone convertase 1 (PC1) in granules at the tips of processes. Expression of PAM-1 resulted in decreased ACTH and PHM secretion in response to secretagogue stimulation, and decreased cleavage of PC1, POMC, and PAM. Increased expression of a soluble form of PAM did not alter POMC and PC1 localization and metabolism. Using the inducible cell line model, we show that expression of integral membrane PAM alters the organization of the actin cytoskeleton. Altered cytoskeletal organization may then influence the trafficking and cleavage of lumenal proteins and eliminate the ability of AtT-20 cells to secrete ACTH in response to a secretagogue.
The Cis-Acting RNA Trafficking Signal from Myelin Basic Protein mRNA and Its Cognate Trans-Acting Ligand Hnrnp A2 Enhance CaP-Dependent Translation
Authors: Kwon Sunjong , Barbarese Elisa , Carson John H.
Published: July 2002

The 21 nucleotide RNA trafficking signal (RTS), originally identified in myelin basic protein mRNA, but also found in a variety of other localized RNAs, is necessary and sufficient for transport of RNA along microtubules in oligodendrocytes. The RTS binds specifically to the RNA binding protein, hnRNP A2. Together, the RTS and hnRNP A2 comprise cis/trans determinants for several steps in the RNA trafficking pathway. Here we show that insertion of the RTS into green fluorescent protein (GFP) RNA enhances translation without affecting stability of microinjected RNA. In dicistronic RNA, the RTS enhances cap-dependent translation without affecting internal ribosome entry site (IRES)-dependent translation. The translation enhancer function of the RTS is position, copy number, and cell type independent, hnRNP A2 dependent, and saturable with increasing amounts of injected RNA. This represents one of the first specific translation enhancer elements identified in a mammalian system.
Glycosylation Can Influence Topogenesis of Membrane Proteins and Reveals Dynamic Reorientation of Nascent Polypeptides within the Translocon
Authors: Goder Veit , Bieri Christoph , Spiess Martin
Published: July 2002

The topology of multispanning membrane proteins in the mammalian endoplasmic reticulum is thought to be dictated primarily by the first hydrophobic sequence. We analyzed the in vivo insertion of a series of chimeric model proteins containing two conflicting signal sequences, i.e., an NH2-terminal and an internal signal, each of which normally directs translocation of its COOH-terminal end. When the signals were separated by more than 60 residues, linear insertion with the second signal acting as a stop-transfer sequence was observed. With shorter spacers, an increasing fraction of proteins inserted with a translocated COOH terminus as dictated by the second signal. Whether this resulted from membrane targeting via the second signal was tested by measuring the targeting efficiency of NH2-terminal signals followed by polypeptides of different lengths. The results show that targeting is mediated predominantly by the first signal in a protein. Most importantly, we discovered that glycosylation within the spacer sequence affects protein orientation. This indicates that the nascent polypeptide can reorient within the translocation machinery, a process that is blocked by glycosylation. Thus, topogenesis of membrane proteins is a dynamic process in which topogenic information of closely spaced signal and transmembrane sequences is integrated.