bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic resonance images of the brain of a dwarf sperm whale (Kogia simus)
Authors: Marino L. , Sudheimer K. , Pabst D. A. , McLellan W. A. , Johnson J. I.
Published: July 2003

Cetacean (dolphin, whale and porpoise) brains are among the least studied mammalian brains because of the difficulty of collecting and histologically preparing such relatively rare and large specimens. Among cetaceans, there exist relatively few studies of the brain of the dwarf sperm whale (Kogia simus). Magnetic resonance imaging (MRI) offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Therefore, MRI has become a critical tool in the study of the brain of cetaceans and other large species. This paper represents the first MRI‐based anatomically labelled three‐dimensional description of the dwarf sperm whale brain. Coronal plane sections of the brain of a sub‐adult dwarf sperm whale were originally acquired and used to produce virtual digital scans in the other two orthogonal spatial planes. A sequential set of images in all three planes has been anatomically labelled and displays the proportions and positions of major neuroanatomical features.
Roles of HNK‐1 carbohydrate epitope and its synthetic glucuronyltransferase genes on migration of rat neural crest cells
Authors: Nagase Takashi , Sanai Yutaka , Nakamura Shun , Asato Hirotaka , Harii Kiyonori , Osumi Noriko
Published: July 2003

HNK‐1 carbohydrate epitope is localized on the surface of avian neural crest cells (NCCs), and is necessary for their migration. However, it is still disputed whether the epitope works in similar ways in mammalian embryos. In this study, we found that HNK‐1 carbohydrate epitope was specifically detected in some of the cranial ganglia, migrating trunk NCCs and some non‐NCC derivatives in the rat embryo. Two genes encoding glucuronyltransferases that synthesize the HNK‐1 epitope in vitro (GlcAT‐P and GlcAT‐D) were recently identified in the rat. Interestingly, the NCCs in the cranial ganglia expressed the GlcAT‐D gene, whereas the migrating trunk NCCs expressed the GlcAT‐P gene. To investigate in vivo functions of the GlcATs in the NCC migration further, we overexpressed GlcAT genes by electroporation in the cranial NCCs in cultured rat embryos. Transfection of both GlcAT genes resulted in efficient synthesis of the HNK‐1 epitope in the NCCs. GlcAT‐P overexpression increased distance of cranial NCC migration, whereas GlcAT‐D overexpression did not show this effect. Our data suggest that the HNK‐1 epitope synthesized by different GlcATs is involved in migration in the sublineages of the NCCs in the rat embryo, and that GlcAT‐P and GlcAT‐D mediate different effects on the NCC migration.
Structural and functional relationships between type 1B heavy metal‐transporting P‐type ATPases in Arabidopsis
Authors: Cobbett Christopher S. , Hussain Dawar , Haydon Michael J.
Published: July 2003

Arabidopsis is remarkable for having eight members of the type 1B heavy metal‐transporting P‐type ATPase subfamily. Sequence analyses indicate that four, two of which may be targeted to plastids, are related to known Cu(I) transporters and contain N‐terminal metal‐binding site (MBS) motifs similar to those identified in other organisms. The remaining four are more closely related to known divalent cation transporters of prokaryotes. Three of these form a closely related group and are believed to be Zn(II) transporters. These contain a predicted N‐terminal MBS that is a variant of those found in Cu transporters in addition to extended C‐terminal regions that contain likely metal‐binding sequences. Our current limited knowledge of the physiological roles of these transporters is reviewed and their evolutionary relationships are explored, including an hypothesis that some, particularly the putative divalent cation transporters, are derived from horizontal gene transfer events.
Schizosaccharomyces pombeas a model for metal homeostasis in plant cells: the phytochelatin‐dependent pathway is the main cadmium detoxification mechanism
Authors: Clemens Stephan , Simm Claudia
Published: July 2003

Sequestration of metal ions by phytochelatins is an important metal tolerance mechanism in a wide range of organisms including plants and certain fungi. Substantial progress in understanding phytochelatin formation at the molecular level has been made inSchizosaccharomyces pombe. The genome ofS. pombehas been completely sequenced and all the necessary tools of functional genomics are available. Since most other proteins implicated in plant metal tolerance and homeostasis are also present in this yeast, it represents a very powerful system to elucidate basic mechanisms of metal buffering, sequestration, and toxicity in cells that form phytochelatins. Here, we summarize the work on phytochelatin formation and metal homeostasis inS. pombe. We describe examples of molecular insights obtained from experiments withS. pombethat will be useful in guiding studies with plants. We also provide evidence for the dominance of the phytochelatin pathway in Cd detoxification inS. pombe.
Pharmacokinetic–pharmacodynamic study of apomorphine's effect on growth hormone secretion in healthy subjects
Authors: Aymard Guy , Berlin Ivan , De Brettes Benoît , Diquet Bertrand
Published: July 2003

Apomorphine (APO) stimulates growth hormone (GH) release via dopamine D2 receptors (DRD2). There is no specific study assessing the relationship between APO pharmacokinetic (PK) and the pharmacodynamic (PD) response e.g. GH release. The objective of the study is the PK–PD modelling of APO in healthy subjects. This is a randomized crossover study with s.c. administration of 5, 10, and 20 μg/kg of APO in 18 healthy subjects. APO concentrations were modelled according to both a bi‐compartmental model with zero‐order absorption and a bi‐compartmental model with first‐order absorption. PK–PD relationship was modelled in accordance with the Emax Hill equation using plasma concentrations of APO calculated according to the bi‐compartmental model with zero‐order absorption. Modelled parameters were very similar to the experimental parameters. PK of APO was linear and there was no significant difference between the tested doses for AUC0→∞ and Cmax (normalised to the dose 1 μg/kg), t1/2α and t1/2β. These parameters expressed as mean (CV%: SD/mean) were: 17.2 (26.9) ng/mL·min, 0.26 (33.3) ng/mL, 17.1 (54.2) and 45.2 (20.6) min, respectively (n = 53).

An anticlockwise hysteresis loop (effect function of APO plasma concentration) appeared for each dose and each subject. The predicted and measured GH concentrations for all subjects and times were similar whatever the dose (P > 0.27). Emax values were 246 (121), 180 (107), 205 (139) ng/mL, respectively, and EC50 were 0.98 (48.1), 1.70 (62.3), 3.67 (65.2) ng/mL, respectively at dose 5, 10, and 20 μg/kg (P < 10−4). APO and GH concentrations were predicted with good accuracy using bi‐compartmental with zero‐order absorption PK model and sigmoid Emax PD model, respectively.
Alzheimer's disease: the pharmacological pathway
Authors: Allain Hervé , Bentué‐Ferrer Danièle , Tribut Olivier , Gauthier Serge , Michel Bernard‐François , Rochelle Christophe Drieu‐La
Published: July 2003

The current pharmacological treatment of Alzheimer's disease (AD) comes down to four marketed drugs (tacrine, donepezil, rivastigmine and galantamine) all of which are cholinesterase inhibitors, conforming to the cholinergic hypothesis. The future is clearly directed at new biological targets closely linked to the pathophysiology of the disease and more precisely, the pathological hallmark of AD which includes widespread neuronal degeneration, neuritic plaques containing β‐amyloid and τ‐rich neurofibrillary tangles. For clinicians, this means that new curative drugs will have to be prescribed early in the course of the disease. This review describes the main entry pathways for drug discovery in AD: (1) supplementation therapy, (2) anti‐apoptotic compounds, (3) substances with a mitochondrial impact, (4) anti‐amyloid substances, (5) anti‐protein aggregation and (6) lipid‐lowering drugs. The rapidity at which these compounds will be at our disposal is highly dependent on the policy of the pharmaceutical companies.
Adverse effects of conventional non‐steroidal anti‐inflammatory drugs on the upper gastrointestinal tract
Authors: Langman Michael J. S.
Published: July 2003

This article reviews the clinical and epidemiological features of conventional non‐steroidal anti‐inflammatory drug (NSAID) related peptic ulcer complications, and the associated risk factors. The degree of gastrointestinal toxicity varies widely between the available drugs and with dose of each. The risk of ulcer complications can however be reduced, and perhaps completely removed, by using the lowest dose of the least toxic member of the class. Enteric coating and other delayed release formulations have not been shown to reduce risk.

Estimates of the imposed disease burden have varied widely, in part through assuming that risks in selected patient groups will necessarily translate to the general population. Nevertheless, the imposed disease burden is one of the largest associated with current drug treatment.

Associated risk factors such as prior ulcer, corticosteroid use and concurrent aspirin as well as general cardiovascular disease will raise the likelihood of an ulcer complication in NSAID takers and non‐takers. Therefore, strategies dependent on substituting COX‐selective drugs will then be only partially successful.
Role of Sonic hedgehog signaling in epithelial and mesenchymal development of hair follicles in an organ culture of embryonic mouse skin
Authors: Nanba Daisuke , Nakanishi Yasuo , Hieda Yohki
Published: July 2003

Studies with gene knockout mice have shown that Sonic hedgehog (Shh) is required for early development of hair follicles, but the role of this gene in the late stages of follicle development is not clear. By using an organ culture system of embryonic mouse skin, the role of Shh signaling in the early and late stages of follicle development was investigated. In the early stage of follicle development, the downward growth of the follicular epithelium was suppressed by cyclopamine, an inhibitor of Shh signaling, and accelerated by recombinant Shh. In addition, cyclopamine impaired dermal papilla formation, accompanied by the rearrangement of papilla cells, but not the elongation of the follicular epithelium at the later stage. These results suggest that Shh signaling is required for the proliferation of epithelial cells in the early development of hair follicles and for the morphogenetic movement of mesenchymal cells at the later stage of follicle development.
Timing system for the start of gastrulation in the Xenopus embryo
Authors: Itoh Takeshi , Shinagawa Atsunori
Published: July 2003

This study examined which component of the egg, the nucleus or cytoplasm, is involved in the timing of the start of gastrulation in the Xenopus embryo, and when it starts to measure time. First, nuclei of cells of 256‐cell stage embryos were transplanted to enucleated eggs 60 min after activation. These eggs showed first cleavage 20–30 min later than control eggs fertilized at the same time as the activation of recipient eggs, and started gastrulation 25–35 min later than control embryos (depending on the delay in the first cleavage). Second, eggs whose nuclei were temporarily isolated by the extrusion of the portion containing the nucleus out of the fertilization envelope showed first cleavage 60–90 min later than sibling control eggs, because of delayed introduction of the nucleus from the extruded portion. They started gastrulation 60–90 min later than sibling control embryos (depending on the delay in the first cleavage). The portion inside the envelope underwent two to three rounds of oscillation in cell cycle relevant activities before the first cleavage, while the portion outside underwent the same rounds of cleavage as the inside portion. From the present and previous results it is concluded that the putative timing system for the start of gastrulation in the Xenopus embryo, whether it consists of a single or of multiple clocks, starts measuring time at or around the first cleavage, and that the presence of both the nucleus and the cytoplasm in the same cell and occurrence of mitosis and/or cleavage there are indispensable for the timing system to work, although the role of the cytoplasm is superior to that of the nucleus.
Plasma lipid modifications in elderly people after administration of two virgin olive oils of the same variety (Olea europaeavar.hojiblanca) with different triacylglycerol composition
Authors: Perona Javier S. , Cañizares Julio , Montero Emilio , Sánchez-Domínguez José M. , Ruiz-Gutierrez Valentina
Published: June 2003

In the present study we examined whether two virgin olive oils (VOO1 and VOO2), of the same variety (Olea europaeavar.hojiblanca) and with a similar composition of minor components but differing in the content of triacylglycerol molecular species, had different effects on blood pressure and plasma lipid levels in a healthy elderly population. Thirty-one participants, aged 84·9 (SD 6·4) years, were asked to participate in the study. No differences were found with regard to blood pressure after both experimental periods (VOO1 and VOO2). However, plasma total cholesterol and LDL-cholesterol were reduced only after VOO1 (P<0·01). The reduction of plasma cholesterol concentrations was related to the incorporation of oleic acid into plasma cholesteryl esters and phospholipids, which was higher after VOO1 (P<0·01). Indeed, the oleic acid concentration in cholesteryl esters and phospholipids strongly correlated with plasma total cholesterol and LDL-cholesterol levels in all experimental periods studied (r2>0·418,P<0·07), except for phospholipids in VOO1 (P=0·130 for total cholesterol andP=0·360 for LDL-cholesterol). These results have demonstrated that blood pressure and plasma lipids can be modified by the consumption of VOO in elderly people, but that the extent of such modification depends on the composition and amount of active minor components and triacylglycerol molecular species.
Do changes in the psychosocial school environment influence pupils' health development? Results from a three-year follow-up study
Authors: Gillander Gadin Katja , Hammarström Anne
Published: July 2003

Aims: This study analysed the effects of psychosocial factors at school on pupils' health and self-worth from a longitudinal perspective. Methods: A three-year prospective study was started in 1994, including 533 pupils (261 girls, 272 boys) from 25 different classes in grades 3 and 6. With age-adjusted questionnaires the changes in self-perceived health were compared with changes in psychosocial school environmental factors. Results: The girls in the older cohort reported a negative health development with decreased self-worth and increased somatic and psychological symptoms. Significant gender differences in ill health, but not in self-worth, developed, especially in the older cohort. A multiple regression analysis showed that a negative development of psychosocial factors at school, measured as control, demand, and classmate problems, was associated with poorer health and self-worth among the pupils. A trichotomization of the psychosocial variables at school indicated a possible causal relationship between psychosocial factors and ill health and self-worth. Conclusions: The negative development in pupils' health and self-worth could partly be explained by the more unfavourable psychosocial environment that prevails at school at the senior level. The public health implications of our study can be summarized as the need for schools to improve pupils' social situation at school in relation to their work situation as well as to pay special attention to the school situation of girls at senior level.
A qualitative study on the determinants of smoking behaviour among adolescents in South Africa
Authors: Panday Saadhna , Reddy Sasiragha P. , Bergström Erik
Published: July 2003

Background: Increasing adolescent smoking rates have highlighted the need for smoking cessation programmes for adolescents. Aim: The aim of this study was to explore adolescent opinions' on the determinants of smoking, with a focus on smoking cessation. Methods: Nine focus group discussions were conducted with grade 8 and 9 school-going smokers and ex-smokers in the Southern Cape Karoo Region, South Africa. Six schools were purposively selected based on their locality (urban or rural) and ethnicity (``black'', ``white'', and ``coloured''). The groups were homogenous in terms of gender and ethnicity. Data was analysed thematically. Results: The majority of the participants declared their intention to stop smoking in the future. They reported multiple quit attempts of short duration. They perceived quitting as a difficult process and that only a few of their friends wanted to stop smoking. Participants believed that they were not addicted to nicotine even though they reported nicotine withdrawal symptoms. While ``coloured'' and ``black'' participants reported their smoking peers as obstacles to quitting, their ``white'' counterparts emphasized that they smoked by choice and that they would support friends who wanted to stop smoking. Conclusion: This study shows that the psychosocial determinants of tobacco use may vary substantially between ethnic groups and cultural contexts. A long-term strategy of poverty reduction that would create greater perceived future prospects is an important consideration for interventions in developing countries. The manifestation of withdrawal symptoms, indicative of nicotine addiction, is a common and significant hindrance for smoking cessation among these adolescents.
Unemployment - an important predictor for future smoking: a 14-year follow-up study of school leavers
Authors: Hammarström Anne , Janlert Urban
Published: July 2003

Aims: To analyse predictors among pupils leaving compulsory school for smoking and high alcohol consumption as adults. Methods: A prospective cohort study in which all pupils (N=1083) in the last year of compulsory school were followed for 14 years. The data were collected through repeated comprehensive self-administered questionnaires. Results: Smoking was better predicted than alcohol intake. The best predictors were earlier high alcohol intake and earlier smoking. Among other predictors, low grades, poor teachers' prognoses and early unemployment pointed to unfavourable health habits, mainly smoking. Conclusions: It is possible already at school to identify risk groups for future smoking and high alcohol consumption.
Measuring social inequalities in health - politics or science?
Authors: Boström Gunnel , Rosen Mans
Published: July 2003

Aims: The methods chosen for seeking the answers to questions on social inequalities in health may heavily influence the results and thereby the formulation of appropriate public health policies. This study aims at identifying methodological problems in analysing trends about socio-economic differences in health. The focus is on whether the results may be influenced by the choice of outcome measure, the choice of social groups or by changes in the composition of social groups over time. Methods: Data sets on socio-economic differences in mortality in Europe presented by Kunst et al. and also data sets from the Swedish Survey of Living Conditions have been used. Results: The choice of outcome measures influences the results. Mortality trend comparisons between European countries for different socio-economic groups give completely different pictures whether using relative or absolute figures. The generally lower death rate in Sweden means that even small absolute differences give higher relative differences than in countries with higher death rates. Using socio-economic group or educational level as indicators of social position showed quite different results when analysing social inequalities in smoking and overweight in Sweden. The structure of social groups changes over time making trend analysis more difficult to interpret. In Sweden the group of poorly-educated people has halved in size during the past two decades, and the group of highly-educated people has increased. These changes most likely make the poorly-educated group a more homogenous and -healthwise - a more negatively selected group than it was twenty years ago. Conclusions: The most appropriate scientific approach to this problem is to present basic data in terms of absolute figures per population before presenting relative or absolute differences.
Dual regulation of neuronal morphogenesis by a δ-catenin–cortactin complex and Rho
Authors: Martinez Maria Cruz , Ochiishi Tomoyo , Majewski Michael , Kosik Kenneth S.
Published: July 2003

δ-Catenin is a neuronal protein that contains 10 Armadillo motifs and binds to the juxtamembrane segment of classical cadherins. We report that δ-catenin interacts with cortactin in a tyrosine phosphorylation–dependent manner. This interaction occurs within a region of the δ-catenin sequence that is also essential for the neurite elongation effects. Src family kinases can phosphorylate δ-catenin and bind to δ-catenin through its polyproline tract. Under conditions when tyrosine phosphorylation is reduced, δ-catenin binds to cortactin and cells extend unbranched primary processes. Conversely, increasing tyrosine phosphorylation disrupts the δ-catenin–cortactin complex. When RhoA is inhibited, δ-catenin enhances the effects of Rho inhibition on branching. We conclude that δ-catenin contributes to setting a balance between neurite elongation and branching in the elaboration of a complex dendritic tree.
Regulated splicing of the fibronectin EDA exon is essential for proper skin wound healing and normal lifespan
Authors: Muro Andrés F. , Chauhan Anil K. , Gajovic Srecko , Iaconcig Alessandra , Porro Fabiola , Stanta Giorgio , Baralle Francisco E.
Published: July 2003

Fibronectins (FNs) are multifunctional high molecular weight glycoproteins present in the blood plasma and in the ECMs of tissues. The FN primary transcript undergoes alternative splicing in three regions generating up to 20 main different variants in humans. However, the precise role of the FN isoforms is poorly understood. One of the alternatively spliced exons is the extra domain A (EDA) or extra type III homology that is regulated spatially and temporally during development and aging. To study its in vivo function, we generated mice devoid of EDA exon-regulated splicing. Constitutive exon inclusion was obtained by optimizing the splice sites, whereas complete exclusion was obtained after in vivo CRE-loxP–mediated deletion of the exon. Homozygous mouse strains with complete exclusion or inclusion of the EDA exon were viable and developed normally, indicating that the alternative splicing at the EDA exon is not necessary during embryonic development. Conversely, mice without the EDA exon in the FN protein displayed abnormal skin wound healing, whereas mice having constitutive inclusion of the EDA exon showed a major decrease in the FN levels in all tissues. Moreover, both mutant mouse strains have a significantly shorter lifespan than the control mice, suggesting that EDA splicing regulation is necessary for efficient long-term maintenance of biological functions.
The Caenorhabditis elegans p120 catenin homologue, JAC-1, modulates cadherin–catenin function during epidermal morphogenesis
Authors: Pettitt Jonathan , Cox Elisabeth A. , Broadbent Ian D. , Flett Aileen , Hardin Jeff
Published: July 2003

The cadherin–catenin complex is essential for tissue morphogenesis during animal development. In cultured mammalian cells, p120 catenin (p120ctn) is an important regulator of cadherin–catenin complex function. However, information on the role of p120ctn family members in cadherin-dependent events in vivo is limited. We have examined the role of the single Caenorhabditis elegans p120ctn homologue JAC-1 (juxtamembrane domain [JMD]–associated catenin) during epidermal morphogenesis. Similar to other p120ctn family members, JAC-1 binds the JMD of the classical cadherin HMR-1, and GFP-tagged JAC-1 localizes to adherens junctions in an HMR-1–dependent manner. Surprisingly, depleting JAC-1 expression using RNA interference (RNAi) does not result in any obvious defects in embryonic or postembryonic development. However, jac-1(RNAi) does increase the severity and penetrance of morphogenetic defects caused by a hypomorphic mutation in the hmp-1/α-catenin gene. In these hmp-1 mutants, jac-1 depletion causes failure of the embryo to elongate into a worm-like shape, a process that involves contraction of the epidermis. Associated with failed elongation is the detachment of actin bundles from epidermal adherens junctions and failure to maintain cadherin in adherens junctions. These results suggest that JAC-1 acts as a positive modulator of cadherin function in C. elegans.
Reduced chondrocyte proliferation and chondrodysplasia in mice lacking the integrin-linked kinase in chondrocytes
Authors: Terpstra Leonieke , Prud'homme Josée , Arabian Alice , Takeda Shu , Karsenty Gérard , Dedhar Shoukat , St-Arnaud René
Published: July 2003

Chondrocyte proliferation and differentiation requires their attachment to the collagen type II–rich matrix of developing bone. This interaction is mediated by integrins and their cytoplasmic effectors, such as the integrin-linked kinase (ILK). To elucidate the molecular mechanisms whereby integrins control these processes, we have specifically inactivated the ILK gene in growth plate chondrocytes using the Cre-lox methodology. Mice carrying an ILK allele flanked by loxP sites (ILK-fl) were crossed to transgenic mice expressing the Cre recombinase under the control of the collagen type II promoter. Inactivation of both copies of the ILK-fl allele lead to a chondrodysplasia characterized by a disorganized growth plate and to dwarfism. Expression of chondrocyte differentiation markers such as collagen type II, collagen type X, Indian hedgehog and the PTH-PTHrP receptor was normal in ILK-deficient growth plates. In contrast, chondrocyte proliferation, assessed by BrdU or proliferating cell nuclear antigen labeling, was markedly reduced in the mutant growth plates. Cell-based assays showed that integrin-mediated adhesion of primary cultures of chondrocytes from mutant animals to collagen type II was impaired. ILK inactivation in chondrocytes resulted in reduced cyclin D1 expression, and this most likely explains the defect in chondrocyte proliferation observed when ILK is inactivated in growth plate cells.
Hrs regulates early endosome fusion by inhibiting formation of an endosomal SNARE complex
Authors: Sun Wei , Yan Qing , Vida Thomas A. , Bean Andrew J.
Published: July 2003

Movement through the endocytic pathway occurs principally via a series of membrane fusion and fission reactions that allow sorting of molecules to be recycled from those to be degraded. Endosome fusion is dependent on SNARE proteins, although the nature of the proteins involved and their regulation has not been fully elucidated. We found that the endosome-associated hepatocyte responsive serum phosphoprotein (Hrs) inhibited the homotypic fusion of early endosomes. A region of Hrs predicted to form a coiled coil required for binding the Q-SNARE, SNAP-25, mimicked the inhibition of endosome fusion produced by full-length Hrs, and was sufficient for endosome binding. SNAP-25, syntaxin 13, and VAMP2 were bound from rat brain membranes to the Hrs coiled-coil domain. Syntaxin 13 inhibited early endosomal fusion and botulinum toxin/E inhibition of early endosomal fusion was reversed by addition of SNAP-25(150–206), confirming a role for syntaxin 13, and establishing a role for SNAP-25 in endosomal fusion. Hrs inhibited formation of the syntaxin 13–SNAP-25–VAMP2 complex by displacing VAMP2 from the complex. These data suggest that SNAP-25 is a receptor for Hrs on early endosomal membranes and that the binding of Hrs to SNAP-25 on endosomal membranes inhibits formation of a SNARE complex required for homotypic endosome fusion.
Bax and Bak can localize to the endoplasmic reticulum to initiate apoptosis
Authors: Zong Wei-Xing , Li Chi , Hatzivassiliou Georgia , Lindsten Tullia , Yu Qian-Chun , Yuan Junying , Thompson Craig B.
Published: July 2003

Bax and Bak play a redundant but essential role in apoptosis initiated by the mitochondrial release of apoptogenic factors. In addition to their presence at the mitochondrial outer membrane, Bax and Bak can also localize to the ER. Agents that initiate ER stress responses can induce conformational changes and oligomerization of Bax on the ER as well as on mitochondria. In wild-type cells, this is associated with caspase 12 cleavage that is abolished in bax−/−bak−/− cells. In bax−/−bak−/− cells, introduction of Bak mutants selectively targeted to either mitochondria or the ER can induce apoptosis. However, ER-targeted, but not mitochondria-targeted, Bak leads to progressive depletion of ER Ca2+ and induces caspase 12 cleavage. In contrast, mitochondria-targeted Bak leads to enhanced caspase 7 and PARP cleavage in comparison with the ER-targeted Bak. These findings demonstrate that in addition to their functions at mitochondria, Bax and Bak also localize to the ER and function to initiate a parallel pathway of caspase activation and apoptosis.
Changes in histone acetylation during mouse oocyte meiosis
Authors: Kim Jin-Moon , Liu Honglin , Tazaki Mayuko , Nagata Masao , Aoki Fugaku
Published: July 2003

We examined global changes in the acetylation of histones in mouse oocytes during meiosis. Immunocytochemistry with specific antibodies against various acetylated lysine residues on histones H3 and H4 showed that acetylation of all the lysines decreased to undetectable or negligible levels in the oocytes during meiosis, whereas most of these lysines were acetylated during mitosis in preimplantation embryos and somatic cells. When the somatic cell nuclei were transferred into enucleated oocytes, the acetylation of lysines decreased markedly. This type of deacetylation was inhibited by trichostatin A, a specific inhibitor of histone deacetylase (HDAC), thereby indicating that HDAC is able to deacetylate histones during meiosis but not during mitosis. Meiosis-specific deacetylation may be a consequence of the accessibility of HDAC1 to the chromosome, because HDAC1 colocalized with the chromosome during meiosis but not during mitosis. As histone acetylation is thought to play a role in propagating the gene expression pattern to the descendent generation during mitosis, and the gene expression pattern of differentiated oocytes is reprogrammed during meiosis to allow the initiation of a new program by totipotent zygotes of the next generation, our results suggest that the oocyte cytoplasm initializes a program of gene expression by deacetylating histones.
Engineered chromosome regions with altered sequence composition demonstrate hierarchical large-scale folding within metaphase chromosomes
Authors: Strukov Yuri G. , Wang Yan , Belmont Andrew S.
Published: July 2003

Mitotic chromosome structure and DNA sequence requirements for normal chromosomal condensation remain unknown. We engineered labeled chromosome regions with altered scaffold-associated region (SAR) sequence composition as a formal test of the radial loop and other chromosome models. Chinese hamster ovary cells were isolated containing high density insertions of a transgene containing lac operator repeats and a dihydrofolate reductase gene, with or without flanking SAR sequences. Lac repressor staining provided high resolution labeling with good preservation of chromosome ultrastructure. No evidence emerged for differential targeting of SAR sequences to a chromosome axis within native chromosomes. SAR sequences distributed uniformly throughout the native chromosome cross section and chromosome regions containing a high density of SAR transgene insertions showed normal diameter and folding. Ultrastructural analysis of two different transgene insertion sites, both spanning less than the full chromatin width, clearly contradicted predictions of simple radial loop models while providing strong support for hierarchical models of chromosome architecture. Specifically, an ∼250-nm-diam folding subunit was visualized directly within fully condensed metaphase chromosomes. Our results contradict predictions of simple radial loop models and provide the first unambiguous demonstration of a hierarchical folding subunit above the level of the 30-nm fiber within normally condensed metaphase chromosomes.
The Runx1 Transcription Factor Inhibits the Differentiation of Naive CD4+ T Cells into the Th2 Lineage by Repressing GATA3 Expression
Authors: Komine Okiru , Hayashi Keitaro , Natsume Waka , Watanabe Toshio , Seki Youichi , Seki Noriyasu , Yagi Ryoji , Sukzuki Wataru , Tamauchi Hidekazu , Hozumi Katsuto , Habu Sonoko , Kubo Masato , Satake Masanobu
Published: July 2003

Differentiation of naive CD4+ T cells into helper T (Th) cells is controlled by a combination of several transcriptional factors. In this study, we examined the functional role of the Runx1 transcription factor in Th cell differentiation. Naive T cells from transgenic mice expressing a dominant interfering form of Runx1 exhibited enhanced interleukin 4 production and efficient Th2 differentiation. In contrast, transduction of Runx1 into wild-type T cells caused a complete attenuation of Th2 differentiation and was accompanied by the cessation of GATA3 expression. Furthermore, endogenous expression of Runx1 in naive T cells declined after T cell receptor stimulation, at the same time that expression of GATA3 increased. We conclude that Runx1 plays a novel role as a negative regulator of GATA3 expression, thereby inhibiting the Th2 cell differentiation.
Bidirectional Interactions between Antigen-bearing Respiratory Tract Dendritic Cells (DCs) and T Cells Precede the Late Phase Reaction in Experimental Asthma
Authors: Huh Joong C. , Strickland Deborah H. , Jahnsen Frode L. , Turner Debra J. , Thomas Jenny A. , Napoli Sylvia , Tobagus Iriani , Stumbles Philip A. , Sly Peter D. , Holt Patrick G.
Published: July 2003

The airway mucosal response to allergen in asthma involves influx of activated T helper type 2 cells and eosinophils, transient airflow obstruction, and airways hyperresponsiveness (AHR). The mechanism(s) underlying transient T cell activation during this inflammatory response is unclear. We present evidence that this response is regulated via bidirectional interactions between airway mucosal dendritic cells (AMDC) and T memory cells. After aerosol challenge, resident AMDC acquire antigen and rapidly mature into potent antigen-presenting cells (APCs) after cognate interactions with T memory cells. This process is restricted to dendritic cells (DCs) in the mucosae of the conducting airways, and is not seen in peripheral lung. Within 24 h, antigen-bearing mature DCs disappear from the airway wall, leaving in their wake activated interleukin 2R+ T cells and AHR. Antigen-bearing activated DCs appear in regional lymph nodes at 24 h, suggesting onward migration from the airway. Transient up-regulation of CD86 on AMDC accompanies this process, which can be reproduced by coculture of resting AMDC with T memory cells plus antigen. The APC activity of AMDC can be partially inhibited by anti-CD86, suggesting that CD86 may play an active role in this process and/or is a surrogate for other relevant costimulators. These findings provide a plausible model for local T cell activation at the lesional site in asthma, and for the transient nature of this inflammatory response.
Presentation of Exogenous Antigens on Major Histocompatibility Complex (MHC) Class I and MHC Class II Molecules Is Differentially Regulated during Dendritic Cell Maturation
Authors: Delamarre Lélia , Holcombe Hilda , Mellman Ira
Published: July 2003

During maturation, dendritic cells (DCs) regulate their capacity to process and present major histocompatibility complex (MHC) II–restricted antigens. Here we show that presentation of exogenous antigens by MHC I is also subject to developmental control, but in a fashion strikingly distinct from MHC II. Immature mouse bone marrow–derived DCs internalize soluble ovalbumin and sequester the antigen intracellularly until they receive an appropriate signal that induces cross presentation. At that time, peptides are generated in a proteasome-dependent fashion and used to form peptide–MHC I complexes that appear at the plasma membrane. Unlike MHC II, these events do not involve a marked redistribution of preexisting MHC I molecules from intracellular compartments to the DC surface. Moreover, out of nine stimuli well known to induce the phenotypic maturation of DCs and to promote MHC II presentation, only two (CD40 ligation, disruption of cell–cell contacts) activated cross presentation on MHC I. In contrast, formation of peptide–MHC I complexes from endogenous cytosolic antigens occurs even in unstimulated, immature DCs. Thus, the MHC I and MHC II pathways of antigen presentation are differentially regulated during DC maturation.
Stat5 Synergizes with T Cell Receptor/Antigen Stimulation in the Development of Lymphoblastic Lymphoma
Authors: Kelly John A. , Spolski Rosanne , Kovanen Panu E. , Suzuki Takeshi , Bollenbacher Julie , Pise-Masison Cynthia A. , Radonovich Michael F. , Lee Stephen , Jenkins Nancy A. , Copeland Neal G. , Morse Herbert C. , Leonard Warren J.
Published: July 2003

Signal transducer and activator of transcription (STAT) proteins are latent transcription factors that mediate a wide range of actions induced by cytokines, interferons, and growth factors. We now report the development of thymic T cell lymphoblastic lymphomas in transgenic mice in which Stat5a or Stat5b is overexpressed within the lymphoid compartment. The rate of lymphoma induction was markedly enhanced by immunization or by the introduction of TCR transgenes. Remarkably, the Stat5 transgene potently induced development of CD8+ T cells, even in mice expressing a class II–restricted TCR transgene, with resulting CD8+ T cell lymphomas. These data demonstrate the oncogenic potential of dysregulated expression of a STAT protein that is not constitutively activated, and that TCR stimulation can contribute to this process.
The Programmed Death-1 (PD-1) Pathway Regulates Autoimmune Diabetes in Nonobese Diabetic (NOD) Mice
Authors: Ansari Mohammed Javeed I. , Salama Alan D. , Chitnis Tanuja , Smith R. Neal , Yagita Hideo , Akiba Hisaya , Yamazaki Tomohide , Azuma Miyuki , Iwai Hideyuki , Khoury Samia J. , Auchincloss Hugh , Sayegh Mohamed H.
Published: July 2003

Programmed death-1 (PD-1) receptor, an inhibitory costimulatory molecule found on activated T cells, has been demonstrated to play a role in the regulation of immune responses and peripheral tolerance. We investigated the role of this pathway in the development of autoimmune diabetes. PD-1 or PD-L1 but not PD-L2 blockade rapidly precipitated diabetes in prediabetic female nonobese diabetic (NOD) mice regardless of age (from 1 to 10-wk-old), although it was most pronounced in the older mice. By contrast, cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) blockade induced disease only in neonates. Male NOD mice also developed diabetes after PD-1–PD-L1 pathway blockade, but NOR mice, congenic to NOD but resistant to the development of diabetes, did not. Insulitis scores were significantly higher and frequency of interferon γ–producing GAD-reactive splenocytes was increased after PD-1–PD-L1 pathway blockade compared with controls. Interestingly, PD-L1 but not PD-L2 was found to be expressed on inflamed islets of NOD mice. These data demonstrate a central role for PD-1–PD-L1 interaction in the regulation of induction and progression of autoimmune diabetes in the NOD mouse and provide the rationale to develop new therapies to target this costimulatory pathway in this disease.
Platelet-activating Factor–mediated NF-κB Dependency of a Late Anaphylactic Reaction
Authors: Choi Il-Whan , Kim Young-Suk , Kim Dae-Ki , Choi Jung-Hwa , Seo Kook-Heon , Im Shun-Young , Kwon Keun-Sang , Lee Myung-Shik , Ha Tai-You , Lee Hern-Ku
Published: July 2003

Anaphylaxis is a life-threatening systemic allergic reaction with the potential for a recurrent or biphasic pattern. Despite an incidence of biphasic reaction between 5 and 20%, the molecular mechanism for the reaction is unknown. Using a murine model of penicillin V–induced systemic anaphylaxis, we show an autoregulatory cascade of biphasic anaphylactic reactions. Induction of anaphylaxis caused a rapid increase in circulating platelet-activating factor (PAF) levels. In turn, the elevated PAF contributes to the early phase of anaphylaxis as well as the subsequent activation of the nuclear factor (NF)-κB, a crucial transcription factor regulating the expression of many proinflammatory cytokines and immunoregulatory molecules. The induction of NF-κB activity is accompanied by TNF-α production, which, in turn, promotes late phase PAF synthesis. This secondary wave of PAF production leads eventually to the late phase of anaphylactic reactions. Mast cells do not appear to be required for development of the late phase anaphylaxis. Together, this work reveals the first mechanistic basis for biphasic anaphylactic reactions and provides possible therapeutic strategies for human anaphylaxis.
Restricted Clonal Expression of IL-2 By Naive T Cells Reflects Differential Dynamic Interactions with Dendritic Cells
Authors: Hurez Vincent , Saparov Arman , Tousson Albert , Fuller Michael J. , Kubo Takekazu , Oliver James , Weaver Benjamin T. , Weaver Casey T.
Published: July 2003

Limited frequencies of T cells express IL-2 in primary antigenic responses, despite activation marker expression and proliferation by most clonal members. To define the basis for restricted IL-2 expression, a videomicroscopic system and IL-2 reporter transgenic model were used to characterize dendritic cell (DC)–T cell interactions. T cells destined to produce IL-2 required prolonged interactions with DCs, whereas most T cells established only transient interactions with DCs and were activated, but did not express IL-2. Extended conjugation of T cells with DCs was not always sufficient to initiate IL-2 expression. Thus, there is intrinsic variability in clonal T cell populations that restricts IL-2 commitment, and prolonged engagement with mature DCs is necessary, but not sufficient, for IL-2 gene transcription.
Iris Pigment Epithelium Expressing CD86 (B7-2) Directly Suppresses T Cell Activation In Vitro via Binding to Cytotoxic T Lymphocyte–associated Antigen 4
Authors: Sugita Sunao , Streilein J. Wayne
Published: July 2003

A monolayer of pigment epithelium (PE) lines the iris PE (IPE), ciliary body PE, and retina PE of the inner eye, an immune-privileged site. These neural crest-derived epithelial cells participate in ocular immune privilege through poorly defined molecular mechanisms. Murine PE cells cultured from different ocular tissues suppress T cell activation by differing mechanisms. In particular, IPE cells suppress primarily via direct cell to cell contact. By examining surface expression of numerous candidate molecules (tumor necrosis factor receptor [TNFR]1, TNFR2, CD36, CD40, CD47, CD80, CD86, PD-L1, CD95 ligand, and type I interferon receptor), we report that IPE cells uniquely express on their surface the costimulatory molecule CD86. When IPE were blocked with anti-CD86 or were derived from CD80/CD86 (but not CD80) knockout (KO) mice, the cells displayed reduced capacity to suppress T cell activation. IPE also failed to suppress activation of T cells in the presence of cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) immunoglobulin or if the T cells were obtained from CTLA-4 (but not CD28) KO mice. We conclude that iris pigment epithelial cells constitutively express cell surface CD86, which enables the cells to contact inhibit T cells via direct interaction with CTLA-4. Thus, ocular immune privilege is achieved in part by subversion of molecules that are usually used for conventional immune costimulation.
Cooperative B7-1/2 (CD80/CD86) and B7-DC Costimulation of CD4+ T Cells Independent of the PD-1 Receptor
Authors: Shin Tahiro , Kennedy Gene , Gorski Kevin , Tsuchiya Haruo , Koseki Haruhiko , Azuma Miyuki , Yagita Hideo , Chen Lieping , Powell Jonathan , Pardoll Drew , Housseau Franck
Published: July 2003

B7-DC is a recently discovered member of the B7 family that binds to PD-1 and is selectively expressed by dendritic cells (DCs). It has been shown to either costimulate or inhibit T cell responses. To assess the role of B7-DC in DC–T cell interactions, DCs from B7-DC knockout (KO) mice were generated and compared with DCs from wild-type (WT) and B7–1/B7–2 double KO mice. B7–1/B7–2–deficient DCs, while strongly diminished in their ability to stimulate naive CD4+ T cells, nonetheless retain partial activity. DCs from B7-DC KO mice are diminished in their ability to activate CD4+ T cells, demonstrating that DC-expressed B7-DC serves a predominantly stimulatory rather than inhibitory function in the initiation of T cell responses. B7-DC costimulates expression of CD40L with faster kinetics than B7–1 and displays potent synergy with B7–1 and B7–2 for T cell proliferation and cytokine production, indicating that these B7 family members work in concert to stimulate T cells. Finally, costimulation with B7-DC alone or in conjunction with B7–1 is PD-1 independent, indicating that B7-DC costimulates T cells via a second receptor.
Influenza Virus–induced Dendritic Cell Maturation Is Associated with the Induction of Strong T Cell Immunity to a Coadministered, Normally Nonimmunogenic Protein
Authors: Brimnes Marie K. , Bonifaz Laura , Steinman Ralph M. , Moran Thomas M.
Published: July 2003

We evaluated the proposal that during microbial infection, dendritic cells (DCs) undergo maturation and present a mixture of peptides derived from the microbe as well as harmless environmental antigens. Mice were exposed to an aerosol of endotoxin free ovalbumin (OVA) in the absence or presence of influenza virus. In its absence, OVA failed to induce B and T cell responses and even tolerized, but with influenza, OVA-specific antibodies and CD8+ cytolytic T lymphocytes developed. With or without infection, OVA was presented selectively in the draining mediastinal lymph nodes, as assessed by the comparable proliferation of infused, CD8+ and CD4+, TCR transgenic T cells. In the absence of influenza, these OVA-specific T cells produced little IL-2, IL-4, IL-10, and IFN-γ, but with infection, both CD4+ and CD8+ T cells made high levels of IL-2 and IFN-γ. The OVA plus influenza-treated mice also showed accelerated recovery to a challenge with recombinant vaccinia OVA virus. CD11c+ DCs from the mediastinal lymph nodes of infected mice selectively stimulated both OVA- and influenza-specific T cells and underwent maturation, with higher levels of MHC class II, CD80, and CD86 molecules. The relatively slow (2–3 d) kinetics of maturation correlated closely to the time at which OVA inhalation elicited specific antibodies. Therefore respiratory infection can induce DC maturation and simultaneously B and T cell immunity to an innocuous antigen inhaled concurrently.