bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological astrocytic calcium levels stimulate glutamate release to modulate adjacent neurons
Authors: Parpura Vladimir , Haydon Philip G.
Published: July 2002

Astrocytes can release glutamate in a calcium-dependent manner and consequently signal to adjacent neurons. Whether this glutamate release pathway is used during physiological signaling or is recruited only under pathophysiological conditions is not well defined. One reason for this lack of understanding is the limited knowledge about the levels of calcium necessary to stimulate glutamate release from astrocytes and about how they compare with the range of physiological calcium levels in these cells. We used flash photolysis to raise internal calcium in astrocytes, while monitoring astrocytic calcium levels and glutamate, which evoked slow inward currents that were recorded electrophysiologically from single neurons grown on microislands of astrocytes. With this approach, we demonstrate that modest changes of astrocytic calcium, from 84 to 140 nM, evoke substantial glutamatergic currents in neighboring neurons (−391 pA), with a Hill coefficient of 2.1 to 2.7. Because the agonists glutamate, norepinephrine, and dopamine all raise calcium in astrocytes to levels exceeding 1.8 μM, these quantitative studies demonstrate that the astrocytic glutamate release pathway is engaged at physiological levels of internal calcium. Consequently, the calcium-dependent release of glutamate from astrocytes functions within an appropriate range of astrocytic calcium levels to be used as a signaling pathway within the functional nervous system.
ATM is a cytoplasmic protein in mouse brain required to prevent lysosomal accumulation
Authors: Barlow Carrolee , Ribaut-Barassin Catherine , Zwingman Theresa A. , Pope Amber J. , Brown Kevin D. , Owens Jennie W. , Larson Denise , Harrington Elizabeth A. , Haeberle Anne-Marie , Mariani Jean , Eckhaus Michael , Herrup Karl , Bailly Yannick , Wynshaw-Boris Anthony
Published: July 2002

We previously generated a mouse model with a mutation in the murine
Atm
gene that recapitulates many aspects of the childhood neurodegenerative disease ataxia-telangiectasia.
Atm
-deficient (
Atm
−/−) mice show neurological defects detected by motor function tests including the rota-rod, open-field tests and hind-paw footprint analysis. However, no gross histological abnormalities have been observed consistently in the cerebellum of any line of
Atm
−/− mice analyzed in most laboratories. Therefore, it may be that the neurologic dysfunction found in these animals is associated with predegenerative lesions. We performed a detailed analysis of the cerebellar morphology in two independently generated lines of
Atm
−/− mice to determine whether there was evidence of neuronal abnormality. We found a significant increase in the number of lysosomes in
Atm
−/− mice in the absence of any detectable signs of neuronal degeneration or other ultrastructural anomalies. In addition, we found that the ATM protein is predominantly cytoplasmic in Purkinje cells and other neurons, in contrast to the nuclear localization of ATM protein observed in cultured cells. The cytoplasmic localization of ATM in Purkinje cells is similar to that found in human cerebellum. These findings suggest that ATM may be important as a cytoplasmic protein in neurons and that its absence leads to abnormalities of cytoplasmic organelles reflected as an increase in lysosomal numbers.
Policing, collective action and social movement theory: the case of the Northern Ireland civil rights campaign*
Authors: Ellison Graham , Martin Greg
Published: July 2002

In this paper we examine the relationship between social movements and the police through an analysis of the Civil Rights Movement (CRM) which emerged in the late 1960s in Northern Ireland. Following della Porta (1995) and Melucci (1996) we argue that the way in which episodes of collective action are policed can affect profoundly both levels of mobilization and the orientation of social movements. We also submit that the symbolic and representational dimensions of policing can be a significant trigger in the stimulation of identification processes and collective action. The paper concludes by questioning some of the assumptions contained within social movement theory, and their applicability to divided societies such as Northern Ireland.
Factors influencing young children’s ability to discriminate unfamiliar faces by age
Authors: George P. A. , Hole G. J. , Scaife M.
Published: July 2002

Three experiments examined young children’s ability to discriminate between pairs of unfamiliar faces which differed in age. Apre-test found that 99% of 6-year-olds, but only 36%of 4-year-olds, could reliably decide which of two faces was the oldest. Experiment 1 attempted to identify the nature of the information used for age-processing faces. Face-pairs were presented in four different versions: Original (unmodified image); Features-only (containing only the internal face features); Skin-blur (in which the skin regions of the face were subjected to Gaussian blurring); or Overall-blur (in which the entire image was blurred). The last three versions selectively reduced specific cues to age. No significant differences in age-discrimination performance were found between these different versions, suggesting that, as with adults, children are capable of adaptively using a variety of cues in order to discriminate between faces on the basis of age.

Experiments 2 and 3 investigated in more detail a phenomenon suggested by Experiment 1: That children found it easier to discriminate between faces by age that were similar in age to themselves, than between adult faces. The results suggest that children as young as 6 years can use age to discriminate between faces of all ages with a relatively high degree of accuracy, but experience most difficulty with adult faces.
The Development of Cognitive Abilities and Social Identities in Children: The Case of Ethnic Identity
Authors: Ocampo Katheryn A. , Knight George P. , Bernal Martha E.
Published: July 2002

The literature on the development of social identities in children has largely adhered to a cognitive developmental framework. However, to date, there has been little or no direct empirical demonstration of cognitive developmental levels associated with age accounting for variations in the expression of social identities. The current study directly assessed this hypothesis within ethnic identity. Ethnic identity in school-age children was assessed with the components outlined by Bernal, Knight, Garza, Ocampo, and Cota (1990), whereas level of cognitive ability was measured with an adaptation of Piaget’s conservation and classification tasks. It was hypothesised that cognitive ability would account for age differences in the components of ethnic self-identification, ethnic constancy, and to a lesser extent, ethnic knowledge. The results demonstrated that level of cognitive ability did not account for the age differences in ethnic self-identification or ethnic constancy. However, they did account for differences in ethnic knowledge. It is possible that the age changes found in ethnic and other social identities may be caused by other age-related changes in development, such as changes in learning through socialisation. This would imply that other phenomena hypothesised to be caused by changes in cognitive ability, such as the development of in-group pride and prejudice in children, may be altered by changes in the way young children are socialised by familial and nonfamilial agents. Research on social identities may bene”t from a departure from cognitive developmental theory and from increased attention to other theories, such as socialisation theory, in understanding the development of ethnic identity and other social identities.
Father Involvement in Sweden: A Longitudinal Study of its Stability and Correlates
Authors: Hwang Carl-Philip , Lamb Michael E.
Published: July 2002

A total of 116 two-parent Swedish families were followed from the time their first-born children averaged 16 months until they were 8.5 years of age. Parents provided time-diary estimates of paternal participation and independent estimates of their relative responsibility and their children’s preferences when the children were 16, 28, 40, 80, and 102 months of age. Children reported on their preferences and their parents’ responsibilities in the last two phases. Analyses showed convergence between parents’ and children’s estimates of paternal involvement and parental preferences, underscoring the reliability of the data. Although poorly correlated with one another, relative and absolute measures of paternal involvement were modestly stable over time, with higher stability evident on reports of relative rather than absolute levels of involvement.
“Still Stable after all This...?”: Temporal Comparison in Coping with Severe and Chronic Disease
Authors: Klauer Thomas , Ferring Dieter , Filipp Sigrun-Heide
Published: July 2002

Temporal comparison theory is used as a conceptual framework for studying coping with life-threatening illness. Propositions derived from this theory were investigated in a questionnaire study on cancer patients ( N = 100). Results reveal high rates of perceived change in the majority of the life domains included in the study, suggesting that consistency could not be maintained in most patients. Furthermore, a disproportion of perceived positive and negative life changes emerged, the latter being more prominent. Change perceptions were related to gender, age, and time elapsed since diagnosis. The relationships between positive and negative change on one hand and adjustment indicators on the other indicated that negative change correlated significantly whereas positive change was not associated with adjustment to illness.
False Belief Prediction and Explanation: Which Develops First and Why it Matters
Authors: Bartsch Karen
Published: July 2002

In response to Wimmer and Mayringer’s (this issue) report “False belief understanding in young children: Explanations do not develop before predictions”, the theoretical importance of the explanation versus prediction issue is expanded and the empirical conclusion of the report is questioned.
Education, citizenship and difference in the South African transition: policy, politics and practice
Authors: Unterhalter Elaine
Published: July 2002

The article looks at three approaches to analysing the relationship between education, citizenship and difference that have been evident in the transition to democracy in South Africa. First, it examines the position that education moulds good citizens and overcomes discriminatory differences, which is evident in the South African Education Policy Act. (This position is similar to that expounded in the Crick Report.) Second, it looks at the view that education is an enactment of citizenship and a celebration of difference. This is articulated in the new South African Curriculum 2005, which celebrates the school as just one of a number of learning spaces, but which is only slowly being implemented with considerable difficulty in overcoming deeply entrenched and multifaceted discriminatory views. Third, it looks at the view, articulated in the South African Constitution of 1996, that education is a relatively autonomous space and that in this particular institutional space education, difference and citizenship are in tension. While there is potential for a creative dialogue to emerge in this historically formed space, preliminary research findings indicate how difficult and diffuse the process of transformation is likely to be.
Stereotypes in cyberspace: writing an anti‐racist website
Authors: Gaine Chris
Published: July 2002

This article deals with some of the difficulties and dilemmas of writing and producing an educational website about ‘race’ and racism (www.britkid.org). With a ‘cast’ of fictionalized characters exploring a wide range of issues relating to racism in the UK, the site is arguably closer to being a mass media product than conventional school materials, and the white, male author had to negotiate complex dilemmas about stereotyping and representation in both the initial drafts and in responding to prepublication feedback. These are explored, together with some reflections upon the relationship between research and a ‘product’ such as this.
A grand day out: towards a mode of interrogation of non‐school pedagogic sites
Authors: Dowling Paul , Brown Andrew
Published: July 2002

Interest is increasingly being taken in educational sites which extend or which are located beyond the school. These include sites associated with developing information and communications technologies and mass media organizations as well as institutions of longer standing, such as museums, galleries and so forth. In this article we shall deploy a sociological framework originally developed for the analysis of school texts to such non‐school sites. Our focus will include considerations of heritage and conservation sites in the form of castles and zoos. We contend that in operating in terms of both pedagogic and exchange relations, such sites may have something to teach as well as something to learn from schooling.
Differential regulation of metalloproteinase production, proliferation and chemotaxis of human lung fibroblasts by PDGF, Interleukin‐1β and TNF‐α
Authors: Sasaki Masahiro , Kashima Masayuki , Ito Takefumi , Watanabe Akiko , Izumiyama Noriko , Sano Masaaki , Kagaya Manabu , Shioya Takanobu , Miura Mamoru
Published: July 2002

Fibroblast migration, proliferation, extracellular matrix protein synthesis and degradation,all of which play important roles in inflammation, are them selves induced by various growth factors and cytokines. Less is known about the interaction of these substances on lung fibroblast function in pulmonary fibrosis.

The goal of this study was to investigate the effects of PDGF alone and in combination with IL–1β and TNF–α on the production of human lung fibroblast matrix metalloproteinases, proliferation, and the chemotactic response. The assay for MMPs activity against FITC labeled type I and IV collagen was based on the specificity of the enzyme cleavage of collagen. Caseinolytis and gelatinolytic activities of secreted proteinases were analyzed by zymography. Fibronectin in conditioned media was measured using human lung fibronectin enzyme immunoassay. Cell proliferation was measured by 3H‐Thymidine incorporation assay. Cell culture supernatants were tested for PGE2 content by ELISA. Chemotactic activity was measured using the modified Boyden chamber.

Matrix metalloproteinase assay indicated that IL–1β, TNF–α and PDGF induced intestitial collagenase (MMP‐1) production. MMP assay also indicated that IL–1β and TNF–α had inhibitory effects on MMP‐2,9(gelatinaseA,B) production. Casein zymography confirmed that IL–1β stimulated stromlysin (matrix metalloproteinase 3; MMP–3) and gelatin zymography demonstrated that TNF–α induced MMP–9 production in human lung fibroblast, whereas PDGF alone did not. PDGF in combination with IL–1β and TNF–α induced MMP–3 and MMP–9 activity, as demonstrated by zymography. PDGF stimulated lung fibroblast proliferation in a concentration‐dependent manner, whereas IL–1β and TNF–α alone had no effect. In contrast, the proliferation of human lung fibroblasts by PDGF was inhibited in the presence of IL–1β and TNF–α, and this inhibition was not a consequence of any elevation of PGE2. PDGF stimulated fibroblast chemotaxis in a concentrationdependent manner, and this stimulation was augmented by combining PDGF with IL–1β and TNF–α.

These findings suggested that PDGF differentially regulated MMPs production in combination with cytokines, and further that MMP assay and zymography had differential sensitivity for detecting MMPs. The presence of cytokines with PDGF appears to modulate the proliferation and chemotaxis of human lung fibroblasts.
Platelet‐activating factor acetylhydrolase and haemophagocytosis in the sepsis syndrome
Authors: Trimoreau Franck , François Bruno , Desachy Arnaud , Besse Arnaud , Vignon Philippe , Denizot Yves
Published: July 2002

Sepsis syndrome (SS) is associated with depressed PAF acetylhydrolase, the enzyme responsible for the degradation of platelet activating factor. PAF acetylhydrolase is in a large part produced by macrophages, whose inadequate activation with haemophagocytosis is frequent in patients with SS.

The aim of this study was to test the hypothesis that PAF acetylhydrolase levels could be affected in these critically ill patients, because of the large amounts produced by activated macrophages in vitro and in vivo in animal models.

The levels of serum PAF acetylhydrolase were assessed in 90 SS patients, who were divided into three groups: patients with (n = 34) or without haemophagocytosis (n = 31), and patients without thrombocytopenia (n = 25) who were used as a control group. The number of organ dysfunctions was matched between patients with haemophagocytosis and controls. Normal reference values were obtained in 59 randomly selected blood donors.

Circulating levels of PAF acetylhydrolase were significantly (p = 0.0001) decreased in patients with SS
(57 ± 3 nnol/ml/min, n = 90) when compared with healthy subjects (69 ± 3 nmol/ml/min,
n = 59). PAF acetylhydrolase levels were greater in the presence of a haemophagocytosis but without statistical significance (64.2 ± 6.5 vs 50.1 ± 2.8: p = 0.25).

Despite the fact that macrophagic activation stimulates the in vitro release of PAF acetylhydrolase, no difference was found between patients with or without haemophagocytosis. The mechanism and the role of the PAF acetylhydrolase reduction in SS patients remain to be determined.
Synthesis of [l‐Nal3] thymopoietin II and examination of its immunological effect on the uremic T‐lymphocytes
Authors: Abiko T. , Nakatsubo S.
Published: July 2002

A TP II analogue, [l‐Nal3] TP II, was synthesized by a conventional solution method, followed by deprotection with 1M TFMSA‐thioanisole (molar ratio 1:1) in TFA in the presence of Me2Se and m‐cresol as scavengers. The synthetic [l‐Nal3] TP II, TP II and [Phe (4 F)3] TP II were tested for comparative effect on the impaired T‐lymphocyte transformation by PHA in uremic patients suffering from recurrent infectious diseases. The synthetic analogue was found to have stronger restorative activity than those of our synthetic TP II and [Phe
(4 F)3] TP II.
Diphenyleneiodonium inhibits NF‐κB activation and iNOS expression induced by IL‐1β: involvement of reactive oxygen species
Authors: Mendes A. Ferreira , Carvalho A. Pato , Caramona M. Margarida , Lopes M. Celeste
Published: July 2002

Aims: In this work, we studied the mechanisms by which diphenyleneiodonium chloride (DPI) inhibits nitric oxide (NO) synthesis induced by the pro‐inflammatory cytokine interleukin‐1β (IL‐1) in bovine articular chondrocytes. To achieve this, we evaluated the ability of DPI to inhibit the expression and activity of the inducible isoform of the NO synthase (iNOS) induced by IL‐1. We also studied the ability of DPI to prevent IL‐1‐induced NF‐κB activation and reactive oxygen species (ROS) production.

Results: Northern and Western blot analysis, respectively, showed that DPI dose‐dependently inhibited IL‐1‐induced iNOS mRNA and protein synthesis in primary cultures of bovine articular chondrocytes. DPI effectively inhibited NO production (IC50 = 0.03 Ī 0.004 μ M), as evaluated by the method of Griess. Nuclear factor‐kappa B (NF‐ κB) activation, as evaluated by electrophoretic mobility shift assay, was inhibited by DPI (1‐10 μ M) in a dose‐dependent manner. IL‐1‐induced ROS production, as evaluated by measurement of dichlorofluorescein fluorescence, was inhibited by DPI at concentrations that also prevented NF‐κB activation and iNOS expression.

Conclusions: DPI inhibits IL‐1‐induced NO production in chondrocytes by two distinct mechanisms: (i) by inhibiting NOS activity, and (ii) by preventing iNOS expression through the blockade of NF‐κB activation. These results also support the involvement of reactive oxygen species in IL‐1‐induced NF‐κB activation and expression of NF‐κB‐dependent genes, such as iNOS.
Tableau Économique and Quesnay's Views on Wealth Power: An Inquiry into Consistency
Authors: Cartelier Jean
Published: July 2002

Loïc Charles and Philippe Steiner (2000) rightly draw our attention to Quesnay's neglected political views, namely the project of making France strong enough to confront England in economic and in military affairs. Schematically, Quesnay insists more upon wealth than upon population, which makes for a difference with most of the economists of his time, and more upon the navy than upon the army. Walter Eltis (1999) carefully relates the “explanations” of the Tableau économique contained in l'Ami des Hommes and the Philosophie rurale to the policy recommendations of Quesnay. He emphasizes the practical character of these different Tableaux in contrast with the abstract character of the first versions and of the Formule. He also gives a detailed account of the efects of diferent policies, namely the extension of grande culture, free trade of corn (which amounts to a higher price of corn), and tax reform. Gianni Vaggi (2001) insists on the modernization of agriculture as a decisive element of the power of a nation. Such preoccupations seem well in accordance with Quesnay's more general concern—that is, refounding the French monarchy on a natural order in which politics and economics can hardly be distinguished.
24‐Hour opiate detoxification and antagonist induction at home–the ‘Asturian method’: a report on 1368 procedures
Authors: CARREñO J. E. , BOBES J. , BREWER C. , ALVAREZ C. E. , SAN NARCISO G. I. , BASCARáN M. T. , DEL RíO J. SáNCHEZ
Published: July 2002

Abstract The technique of domiciliary rapid opiate detoxification (ROD) developed in Asturias since 1994 enables patients dependent on heroin and/or methadone (or other opiates) to start antagonist maintenance with a full dose of naltrexone (50 mg) and largely recover from the acute opiate withdrawal syndrome in a few hours at home without direct medical or nursing involvement. Detailed information on 1368 procedures is presented but in Asturias, over 3000 procedures have been completed to date without any deaths or serious medical or psychiatric complications. We also describe some recent modifications to the procedure involving the use of octreotide as an antidiarrhoeal and the insertion of subcutaneous naltrexone implants to prevent early relapse. Rather than domiciliary ROD, we think the procedure is more usefully conceptualized as domiciliary rapid antagonist induction (RAI), because treatment with well‐supervised naltrexone is known to be effective in reducing relapse rates. Now that controlled studies uniformly describe greatly increased rates of transfer to naltrexone meaintenance treatment following RAI, compared with conventional slower withdrawal and naltrexone induction procedures, it is important that the safety, acceptability and simplicity of this ‘Asturian’ RAI/ROD technique become more widely known.
Ethanol metabolism, toxicity and genetic polymorphism
Authors: IWAHASHI KAZUHIKO , SUWAKI HIROSHI
Published: July 2002

The relationships between the individual (and racial) differences in alcohol metabolism and toxicity, and the genetic polymorphism of alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), and cytochrome P‐4502E1(CYPIIE1) were reviewed. In recent studies involving DNA analysis, it was found that a deficiency of the ALDH2 isozyme (ALDH2*2) was responsible for the flushing symptoms as well as other vasomotor symptoms caused by a higher acetaldehyde level after alcohol consumption. Deficiency of ALDH2 activity has been found prevalently only among people of Mongoloid origin, and the deficiency of ALDH2 prevents them from developing alcohol dependence due to the unpleasant physical effects of the flushing symptom. It was reported that Mongoloids such as Japanese and Chinese people carry the enzymatically active (ALDH2*1) subunit and/or the inactive (ALDH2*2) one, and that a low proportion of ALDH2 deficiency (ALDH2*2 allele frequency) was found in alcoholics compared with healthy controls. It was also reported that polymorphism of ALDH2 and/or CYP2E1 may be associated with the susceptibility to alcohol‐induced liver injury. Concerning blood ethanol elimination kinetics, it was reported that the c2 gene of CYP2E1 and the ALDH2*1 gene may have greater effects on ethanol and acetaldehyde elimination than the other genotypes, when the blood ethanol level is below 20 m M.
Extraskeletal Osteosarcoma of the Orbit
Authors: Jacob Rojymon , Abraham Elizabeth , Jyothirmayi Rema , Nair Madhavan Krishnan
Published: July 2002

Patient. We report a 22‐year‐old male presenting with extraskeletal osteosarcoma of the orbit.

Discussion. Extra skeletal osteosarcomas are uncommon tumours, usually arising from the lower extremities or girdle. These are aggressive tumours with high metastatic potential and poor outcome. Optimal treatment is undefined, and the role of radical surgery, radiotherapy and aggressive chemotherapy is currently being evaluated. The orbit is a rare site for
extraskeletal osteosarcoma, with the only previous case reported in an 11‐year‐old male, who was irradiated in infancy for a retinoblastoma.
Lip, a Human Gene Detected by Transfection of DNA From a Human Liposarcoma Encodes a Protein With Homology to Regulators of Small G Proteins
Authors: Patterson Helen , Gill Sandra , Benjamin Harry , Mitchell Philip J. , Cooper Colin S.
Published: July 2002

Purpose/Method. Transfection experiments have been used to identify activated oncogenes in a wide variety of tumour types. Here we describe the use of transfection experiments utilizing DNA from a human pleomorphic liposarcoma to identify a novel gene, designated lip which maps to chromosome 19.

Results. lip was expressed in all sarcoma cell lines examined and a wide variety of normal tissues. Sequencing of cDNAs prepared from transcripts of the normal lip gene indicates that lip is predicted to encode a 966 amino acid protein with a region of homology to proteins such as vav, dbl, lbc and ect-2 which act as GDP–GTP exchange factors for the RAS superfamily of small GTP‐binding proteins, and the N‐terminal 830 amino acids are identical to the recently identified
gene p115‐RhoGEF, an exchange factor for RHOA. In transfectants, lip has undergone a rearrangement which results in C‐terminal truncation of the predicted LIP protein. However, we failed to detect this alteration in the primary liposarcoma used in the original transfection experiments, or in other sarcoma specimens examined.

Discussion. When considered together, these observations suggest that transforming lip sequences represent an alternatively spliced form of p115‐RhoGEF that is activated for transformation by C‐terminal truncation during transfection, and
is not widely involved in sarcoma development.
Malignant Chondroblastoma of the Os Calcis
Authors: Elek Emil M. , Grimer Robert J. , Mangham David C. , Davies A. Mark , Carter Simon R. , Tillman Roger M.
Published: July 2002

Patient. We describe a case of chondroblastoma of the os calcis which metastasized to the tibia, soft tissues and lung. A complete response of the lung lesions was noted with chemotherapy.

Discussion. Review of the published literature shows that metastatic chondroblastoma only arises following local recurrence of the tumour.
Bilateral Endoprosthetic Replacements of the Proximal Femur
Authors: Foukas Athanasios F. , Grimer Robert J.
Published: July 2002

Patient. We report the case of a 20‐year‐old caucasian male with an Ewing′s sarcoma in the left upper femur. After induction chemotherapy, he underwent resection of the left upper femur and insertion of a cemented proximal femoral replacement. Four years later, he presented with a solitary bone metastasis in the right upper femur. He underwent further chemotherapy followed by resection and endoprosthetic replacement of the other proximal femur. He remains disease free with excellent function almost a year after the second operation.

Discussion. We believe this is the first reported case of bilateral proximal femoral endoprostheses.
Spatial Relationship between Transcription Sites and Chromosome Territories
Authors: Verschure Pernette J. , van der Kraan Ineke , Manders Erik M.M. , van Driel Roel
Published: July 2002

We have investigated the spatial relationship between transcription sites and chromosome territories in the interphase nucleus of human female fibroblasts. Immunolabeling of nascent RNA was combined with visualization of chromosome territories by fluorescent in situ hybridization (FISH). Transcription sites were found scattered throughout the territory of one of the two X chromosomes, most likely the active X chromosome, and that of both territories of chromosome 19. The other X chromosome territory, probably the inactive X chromosome, was devoid of transcription sites. A distinct substructure was observed in interphase chromosome territories. Intensely labeled subchromosomal domains are surrounded by less strongly labeled areas. The intensely labeled domains had a diameter in the range of 300–450 nm and were sometimes interconnected, forming thread-like structures. Similar large scale chromatin structures were observed in HeLa cells expressing green fluorescent protein (GFP)-tagged histone H2B. Strikingly, nascent RNA was almost exclusively found in the interchromatin areas in chromosome territories and in between strongly GFP-labeled chromatin domains. These observations support a model in which transcriptionally active chromatin in chromosome territories is markedly compartmentalized. Active loci are located predominantly at or near the surface of compact chromatin domains, depositing newly synthesized RNA directly into the interchromatin space.
Gap43, Marcks, and Cap23 Modulate Pi(4,5)p2 at Plasmalemmal Rafts, and Regulate Cell Cortex Actin Dynamics through a Common Mechanism
Authors: Laux Thorsten , Fukami Kiyoko , Thelen Marcus , Golub Tamara , Frey Dunja , Caroni Pico
Published: July 2002

The dynamic properties of the cell cortex and its actin cytoskeleton determine important aspects of cell behavior and are a major target of cell regulation. GAP43, myristoylated alanine-rich C kinase substrate (MARCKS), and CAP23 (GMC) are locally abundant, plasmalemma-associated PKC substrates that affect actin cytoskeleton. Their expression correlates with morphogenic processes and cell motility, but their role in cortex regulation has been difficult to define mechanistically. We now show that the three proteins accumulate at rafts, where they codistribute with PI(4,5)P2, and promote its retention and clustering. Binding and modulation of PI(4,5)P2 depended on the basic effector domain (ED) of these proteins, and constructs lacking the ED functioned as dominant inhibitors of plasmalemmal PI(4,5)P2 modulation. In the neuronlike cell line, PC12, NGF- and substrate-induced peripheral actin structures, and neurite outgrowth were greatly augmented by any of the three proteins, and suppressed by ΔED mutants. Agents that globally mask PI(4,5)P2 mimicked the effects of GMC on peripheral actin recruitment and cell spreading, but interfered with polarization and process formation. Dominant negative GAP43(ΔED) also interfered with peripheral nerve regeneration, stimulus-induced nerve sprouting and control of anatomical plasticity at the neuromuscular junction of transgenic mice. These results suggest that GMC are functionally and mechanistically related PI(4,5)P2 modulating proteins, upstream of actin and cell cortex dynamics regulation.
The Dendritic Cell Receptor for Endocytosis, Dec-205, Can Recycle and Enhance Antigen Presentation via Major Histocompatibility Complex Class II–Positive Lysosomal Compartments
Authors: Mahnke Karsten , Guo Ming , Lee Sena , Sepulveda Homero , Swain Suzy L. , Nussenzweig Michel , Steinman Ralph M.
Published: July 2002

Many receptors for endocytosis recycle into and out of cells through early endosomes. We now find in dendritic cells that the DEC-205 multilectin receptor targets late endosomes or lysosomes rich in major histocompatibility complex class II (MHC II) products, whereas the homologous macrophage mannose receptor (MMR), as expected, is found in more peripheral endosomes. To analyze this finding, the cytosolic tails of DEC-205 and MMR were fused to the external domain of the CD16 Fcγ receptor and studied in stable L cell transfectants. The two cytosolic domains each mediated rapid uptake of human immunoglobulin (Ig)G followed by recycling of intact CD16 to the cell surface. However, the DEC-205 tail recycled the CD16 through MHC II–positive late endosomal/lysosomal vacuoles and also mediated a 100-fold increase in antigen presentation. The mechanism of late endosomal targeting, which occurred in the absence of human IgG, involved two functional regions: a membrane-proximal region with a coated pit sequence for uptake, and a distal region with an EDE triad for the unusual deeper targeting. Therefore, the DEC-205 cytosolic domain mediates a new pathway of receptor-mediated endocytosis that entails efficient recycling through late endosomes and a greatly enhanced efficiency of antigen presentation to CD4+ T cells.
Human Survivin Is a Kinetochore-Associated Passenger Protein
Authors: Skoufias Dimitrios A. , Mollinari Cristiana , Lacroix Françoise B. , Margolis Robert L.
Published: July 2002

Survivin, a dimeric baculovirus inhibitor of apoptosis repeat (BIR) motif protein that is principally expressed in G2 and mitosis, has been associated with protection against apoptosis of cells that exit mitosis aberrantly. Mammalian survivin has been reported to associate with centrosomes and with the mitotic spindle. We have expressed a human hemagglutinin-tagged survivin plasmid to determine its localization, and find instead that it clearly acts as a passenger protein. In HeLa cells, survivin first associates with the kinetochores, and then translocates to the spindle midzone during anaphase and, finally, to the midbody during cell cleavage. Its localization is similar to that of TD-60, a known passenger protein. Both a point mutation in the baculovirus IAP repeat motif (C84A) and a COOH-terminal deletion mutant (Δ106) of survivin fail to localize to either kinetochores or midbodies, but neither interferes with cell cleavage. The interphase localization of survivin is cell cycle regulated since in permanently transfected NIH3T3 cells it is excluded from the nuclei until G2, where it localizes with centromeres. Survivin remains associated with mitotic kinetochores when microtubule assembly is disrupted and its localization is thus independent of microtubules. We conclude that human survivin is positioned to have an important function in the mechanism of cell cleavage.
The Toxoplasma gondii protein ROP2 mediates host organelle association with the parasitophorous vacuole membrane
Authors: Sinai Anthony P. , Joiner Keith A.
Published: July 2002

Toxoplasma gondii replicates within a specialized vacuole surrounded by the parasitophorous vacuole membrane (PVM). The PVM forms intimate interactions with host mitochondria and endoplasmic reticulum (ER) in a process termed PVM–organelle association. In this study we identify a likely mediator of this process, the parasite protein ROP2. ROP2, which is localized to the PVM, is secreted from anterior organelles termed rhoptries during parasite invasion into host cells. The NH2-terminal domain of ROP2 (ROP2hc) within the PVM is exposed to the host cell cytosol, and has characteristics of a mitochondrial targeting signal. In in vitro assays, ROP2hc is partially translocated into the mitochondrial outer membrane and behaves like an integral membrane protein. Although ROP2hc does not translocate across the ER membrane, it does exhibit carbonate-resistant binding to this organelle. In vivo, ROP2hc expressed as a soluble fragment in the cytosol of uninfected cells associates with both mitochondria and ER. The 30–amino acid (aa) NH2-terminal sequence of ROP2hc, when fused to green fluorescent protein (GFP), is sufficient for mitochondrial targeting. Deletion of the 30-aa NH2-terminal signal from ROP2hc results in robust localization of the truncated protein to the ER. These results demonstrate a new mechanism for tight association of different membrane-bound organelles within the cell cytoplasm.
Junctional adhesion molecule (JAM) binds to PAR-3
Authors: Itoh Masahiko , Sasaki Hiroyuki , Furuse Mikio , Ozaki Harunobu , Kita Toru , Tsukita Shoichiro
Published: July 2002

At tight junctions (TJs), claudins with four transmembrane domains are incorporated into TJ strands. Junctional adhesion molecule (JAM), which belongs to the immunoglobulin superfamily, is also localized at TJs, but it remains unclear how JAM is integrated into TJs. Immunoreplica electron microscopy revealed that JAM showed an intimate spatial relationship with TJ strands in epithelial cells. In L fibroblasts expressing exogenous JAM, JAM was concentrated at cell–cell adhesion sites, where there were no strand-like structures, but rather characteristic membrane domains free of intramembranous particles were detected. These domains were specifically labeled with anti-JAM polyclonal antibody, suggesting that JAM forms planar aggregates through their lateral self-association. Immunofluorescence microscopy and in vitro binding assays revealed that ZO-1 directly binds to the COOH termini of claudins and JAM at its PDZ1 and PDZ3 domains, respectively. Furthermore, another PDZ-containing polarity-related protein, PAR-3, was directly bound to the COOH terminus of JAM, but not to that of claudins. These findings led to a molecular architectural model for TJs: small aggregates of JAM are tethered to claudin-based strands through ZO-1, and these JAM aggregates recruit PAR-3 to TJs. We also discuss the importance of this model from the perspective of the general molecular mechanisms behind the recruitment of PAR proteins to plasma membranes.
Different modes of hypertrophy in skeletal muscle fibers
Authors: Paul Angelika C. , Rosenthal Nadia
Published: July 2002

Skeletal muscles display a remarkable diversity in their arrangement of fibers into fascicles and in their patterns of innervation, depending on functional requirements and species differences. Most human muscle fascicles, despite their great length, consist of fibers that extend continuously from one tendon to the other with a single nerve endplate band. Other mammalian muscles have multiple endplate bands and fibers that do not insert into both tendons but terminate intrafascicularly. We investigated whether these alternate structural features may dictate different modes of cell hypertrophy in two mouse gracilis muscles, in response to expression of a muscle-specific insulin-like growth factor (IGF)-1 transgene (mIGF-1) or to chronic exercise. Both hypertrophic stimuli independently activated GATA-2 expression and increased muscle cross-sectional area in both muscle types, with additive effects in exercising myosin light chain/mIGF transgenic mice, but without increasing fiber number. In singly innervated gracilis posterior muscle, hypertrophy was characterized by a greater average diameter of individual fibers, and centralized nuclei. In contrast, hypertrophic gracilis anterior muscle, which is multiply innervated, contained longer muscle fibers, with no increase in average diameter, or in centralized nuclei. Different modes of muscle hypertrophy in domestic and laboratory animals have important implications for building appropriate models of human neuromuscular disease.
Distinct retrieval and retention mechanisms are required for the quality control of endoplasmic reticulum protein folding
Authors: Vashist Shilpa , Kim Woong , Belden William J. , Spear Eric D. , Barlowe Charles , Ng Davis T.W.
Published: July 2002

Proteins destined for the secretory pathway must first fold and assemble in the lumen of endoplasmic reticulum (ER). The pathway maintains a quality control mechanism to assure that aberrantly processed proteins are not delivered to their sites of function. As part of this mechanism, misfolded proteins are returned to the cytosol via the ER protein translocation pore where they are ubiquitinated and degraded by the 26S proteasome. Previously, little was known regarding the recognition and targeting of proteins before degradation. By tracking the fate of several mutant proteins subject to quality control, we demonstrate the existence of two distinct sorting mechanisms. In the ER, substrates are either sorted for retention in the ER or are transported to the Golgi apparatus via COPII–coated vesicles. Proteins transported to the Golgi are retrieved to the ER via the retrograde transport system. Ultimately, both retained and retrieved proteins converge at a common machinery at the ER for degradation. Furthermore, we report the identification of a gene playing a novel role specific to the retrieval pathway. The gene, BST1, is required for the transport of misfolded proteins to the Golgi, although dispensable for the transport of many normal cargo proteins.
Identification of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) as the Rosetting Ligand of the Malaria Parasite P. falciparum
Authors: Chen Qijun , Barragan Antonio , Fernandez Victor , Sundström Annika , Schlichtherle Martha , Sahlén Anders , Carlson Johan , Datta Santanu , Wahlgren Mats
Published: July 2002

Severe Plasmodium falciparum malaria is characterized by excessive sequestration of infected and uninfected erythrocytes in the microvasculature of the affected organ. Rosetting, the adhesion of P. falciparum–infected erythrocytes to uninfected erythrocytes is a virulent parasite phenotype associated with the occurrence of severe malaria. Here we report on the identification by single-cell reverse transcriptase PCR and cDNA cloning of the adhesive ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting PfEMP1 contains clusters of glycosaminoglycan-binding motifs. A recombinant fusion protein (Duffy binding-like 1–glutathione S transferase; Duffy binding-like-1–GST) was found to adhere directly to normal erythrocytes, disrupt naturally formed rosettes, block rosette reformation, and bind to a heparin-Sepharose matrix. The adhesive interactions could be inhibited with heparan sulfate or enzymes that remove heparan sulfate from the cell surface whereas other enzymes or similar glycosaminoglycans of a like negative charge did not affect the binding. PfEMP1 is suggested to be the rosetting ligand and heparan sulfate, or a heparan sulfate–like molecule, the receptor both for PfEMP1 binding and naturally formed erythrocyte rosettes.
The Trypanosoma cruzi trans-Sialidase, through Its Cooh-Terminal Tandem Repeat, Upregulates Interleukin 6 Secretion in Normal Human Intestinal Microvascular Endothelial Cells and Peripheral Blood Mononuclear Cells
Authors: Saavedra Emma , Herrera Macario , Gao Wenda , Uemura Haruki , Pereira Miercio A.
Published: July 2002

The Trypanosoma cruzi trans-sialidase can sensitize mice to become highly susceptible to T. cruzi invasion, through mechanisms that remain unknown. In pursuing this observation, we found that purified trans-sialidase induces the selective release of biologically active interleukin (IL)-6 in naive human intestinal microvascular endothelial cells (HIMECs), peripheral blood mononuclear cells (PBMCs), and bladder carcinoma cells. The trans-sialidase action was independent of its catalytic activity, as demonstrated with a genetically engineered trans-sialidase mutant, an enzymatically active polypeptide, and cocultures of PBMCs with epimastigotes and trypomastigotes. Instead, the trans-sialidase action was reproduced with a recombinant COOH-terminal tandem repeat and with synthetic peptides modeled on the tandem repeat. Most interesting, HIMECs infected with a trypomastigote population expressing trans-sialidase effectively released IL-6, but did not upon infection with the counterpart trypomastigote population expressing low trans-sialidase levels. IL-6 is a key factor in the regulation and symptom formation of infection caused by several types of viruses, such as HIV and influenza A virus. However, the function of IL-6 in protozoan and other parasitic diseases remains unclear. The unique findings presented here suggest that trans-sialidase is a major inducer of IL-6 secretion in T. cruzi infection, independently of immune cell activation. Such IL-6 secretion might underlie some features of Chagas's disease, such as pyrexia, neuroprotection, and fibrosis, and might result in the undermining of normal acquired immunity against T. cruzi.
Metabolic Depletion of Atp by Fructose Inversely Controls Cd95- and Tumor Necrosis Factor Receptor 1–Mediated Hepatic Apoptosis
Authors: Latta Markus , Künstle Gerald , Leist Marcel , Wendel Albrecht
Published: July 2002

Hepatocyte apoptosis is crucial in several forms of liver disease. Here, we examined in different models of murine liver injury whether and how metabolically induced alterations of hepatocyte ATP levels control receptor-mediated apoptosis. ATP was depleted either in primary hepatocytes or in vivo by various phosphate-trapping carbohydrates such as fructose. After the activation of the tumor necrosis factor (TNF) receptor or CD95, the extent of hepatocyte apoptosis and liver damage was quantified. TNF-induced cell death was completely blocked in ATP-depleted hepatocyte cultures, whereas apoptosis mediated by CD95 was enhanced. Similarly, acute TNF-induced liver injury in mice was entirely inhibited by ATP depletion with ketohexoses, whereas CD95-mediated hepatotoxicity was enhanced. ATP depletion prevented mitochondrial cytochrome c release, loss of mitochondrial membrane potential, activation of type II caspases, DNA fragmentation, and cell lysis after exposure to TNF. The extent of apoptosis inhibition correlated with the severity of ATP depletion, and TNF-induced apoptosis was restored when ATP was repleted by increasing the extracellular phosphate concentration. Our study demonstrates that TNF-induced hepatic apoptosis can be selectively and reversibly blocked upstream of mitochondrial dysfunction by ketohexose-mediated ATP depletion.
Inhibition of T1/St2 during Respiratory Syncytial Virus Infection Prevents T Helper Cell Type 2 (Th2)- but Not Th1-Driven Immunopathology
Authors: Walzl Gerhard , Matthews Stephen , Kendall Sharon , Gutierrez-Ramos Jose Carlos , Coyle Anthony J. , Openshaw Peter J.M. , Hussell Tracy
Published: July 2002

T cells secreting interleukin (IL)-4 and IL-5 (T helper cell type 2 [Th2] cells) play a detrimental role in a variety of diseases, but specific methods of regulating their activity remain elusive. T1/ST2 is a surface ligand of the IL-1 receptor family, expressed on Th2- but not on interferon (IFN)-γ–producing Th1 cells. Prior exposure of BALB/c mice to the attachment (G) or fusion (F) protein of respiratory syncytial virus (RSV) increases illness severity during intranasal RSV challenge, due to Th2-driven lung eosinophilia and exuberant Th1-driven pulmonary infiltration, respectively. We used these polar models of viral illness to study the recruitment of T1/ST2 cells to the lung and to test the effects of anti-T1/ST2 treatment in vivo. T1/ST2 was present on a subset of CD4+ cells from mice with eosinophilic lung disease. Monoclonal anti-T1/ST2 treatment reduced lung inflammation and the severity of illness in mice with Th2 (but not Th1) immunopathology. These results show that inhibition of T1/ST2 has a specific effect on virally induced Th2 responses and suggests that therapy targeted at this receptor might be of value in treating Th2-driven illness.
‘Full and open access’ to scientific information: an academic's view
Authors: Berry R. Stephen
Published: July 2002

Stimulated by the potential of electronic distribution of information, discussions, sometimes rather tense, about the ownership and proprietary rights to scientific publications have generated something of a polarization of the communities that have stakes in this issue. There are some ‘middle‐grounders’, but the intensity of the discourse has made them less visible than the spokesmen for the extremes. In this forum, we examine these positions and then present a case for a specific policy, in light of the views of the parties.