bluuebunny/crossref_metadata_2025 huggingface dataset:
Bias in dietary-report instruments and its implications for nutritional epidemiology
Authors: Kipnis Victor , Midthune Douglas , Freedman Laurence , Bingham Sheila , Day Nicholas E , Riboli Elio , Ferrari Pietro , Carroll Raymond J
Published: July 2003

Objective:

To evaluate measurement error structure in dietary assessment instruments and to investigate its implications for nutritional studies, using urinary nitrogen excretion as a reference biomarker for protein intake.

Design:

The dietary assessment methods included different food-frequency questionnaires (FFQs) and such conventional dietary-report reference instruments as a series of 24-hour recalls, 4-day weighed food records or 7-day diaries.

Setting:

Six original pilot validation studies within the European Prospective Investigation of Cancer (EPIC), and two validation studies conducted by the British Medical Research Council (MRC) within the Norfolk cohort that later joined as a collaborative component cohort of EPIC.

Subjects:

A sample of approximately 100 to 200 women and men, aged 35–74 years, from each of eight validation studies.

Results:

In assessing protein intake, all conventional dietary-report reference methods violated the critical requirements for a valid reference instrument for evaluating, and adjusting for, dietary measurement error in an FFQ. They displayed systematic bias that depended partly on true intake and partly was person-specific, correlated with person-specific bias in the FFQ. Using the dietary-report methods as reference instruments produced substantial overestimation (up to 230%) of the FFQ correlation with true usual intake and serious underestimation (up to 240%) of the degree of attenuation of FFQ-based log relative risks.

Conclusion:

The impact of measurement error in dietary assessment instruments on the design, analysis and interpretation of nutritional studies may be much greater than has been previously estimated, at least regarding protein intake.
Assessing the dietary environment: examples from school-based nutrition interventions
Authors: Lytle Leslie A , Fulkerson Jayne A
Published: July 2003

Objective:

The objectives of this paper are to (1) introduce the concept of upstream and downstream public health approaches and discuss diet assessment issues in that context, and (2) provide examples of diet assessment methods and challenges in assessing environmental factors influencing eating patterns.

Design:

Dietary assessment of environmental factors is discussed as they relate to nutrition interventions for school-aged children, although the issues transcend population characteristics. Examples of assessment challenges in measuring ‘dietary environments’ are drawn from the Child and Adolescent Trial for Cardiovascular Health (CATCH), Teens Eating for Energy and Nutrition at School (TEENS) and Trying Alternative Cafeteria Options in Schools (TACOS) studies.

Results/conclusions:

The healthfulness of our ‘dietary environments’ (which may include food availability, social norms around food choice and the effect of pricing, policy and promotion on food choice) may be more important in determining what people consume than their individual decision-making about food choice. There is a dearth of published information to inform us on how to assess these ‘dietary environments’.
Issues in the development and use of food composition databases
Authors: Puwastien Prapasri
Published: July 2003

Objectives:

To share experience on the development of national and regional food composition tables (FCTs) and the issues and problems involved.

Design:

Food composition data analysed at national and regional levels were compiled. Systematic development of FCTs detailing specific criteria and characteristics following the INFOODS and ASEANFOODS guidelines was conducted.

Setting:

The national FCT was developed using the Thai FCT as a study model. For the regional level, the Association of South East Asian Nations (ASEAN) FCT was developed.

Subjects:

About 3000 analysed datasets of about 1000 food items on proximate composition, minerals, vitamins and other available components from various sources in Thailand and about 4500 analysed datasets of 1700 food items on the same components from various countries in ASEAN were compiled. The national and regional FCTs were then developed systematically.

Results:

The developed Thai FCT contains 24 nutrients of 1055 food items and the ASEAN FCT contains 21 nutrients of about 1740 food items. Issues and problems regarding the development and use of national and regional food composition data are listed.

Conclusion:

Food composition databases have become increasingly important in the international health arena. Systematic compilation of the data is necessary and the use of INFOODS tag names is strongly recommended. This is to indicate the methods of nutrient analysis and calculation, and to facilitate international and regional data interchange. Users are also recommended to read theExplanatory Notes and Information to the Users.Collaboration among data generators, users and compilers at national and regional levels, as well as support from international organisations, is essential.
Procedures for screening out inaccurate reports of dietary energy intake
Authors: Mccrory Megan A , Hajduk Cheryl L , Roberts Susan B
Published: July 2003

Objective:

To review existing methods and illustrate the use of a new, simple method for identifying inaccurate reports of dietary energy intake (rEI).

Design:

Comparison of rEI with energy requirements estimated by using total energy expenditure predicted (pTEE) from age, weight, height and sex using a previously published equation. Propagation of error calculations was performed and cut-offs for excluding rEI at plus or minus two standard deviations (±2 SD) and ±1 SD for the agreement between rEI and pTEE were established.

Setting:

Dietary survey in a US national cohort: the Continuing Survey of Food Intakes by Individuals (CSFII), 1994–96.

Subjects:

Men and non-pregnant, non-lactating women aged 21–45 years in the CSFII who provided two multiple-pass 24-hour recalls, height and weight(n = 3755).

Results:

Average rEI was 77% of pTEE in men, and 64% of pTEE in women. Calculated cut-offs were rEI <40% or >160% of pTEE (±2 SD) and <70% or >130% of pTEE (±1 SD), respectively. Use of only the ±1 SD cut-offs, not the ±2 SD cut-offs, resulted in a relationship between rEI and body weight similar to what was expected (based on an independently calculated relationship between rEI and measured TEE). Exclusion of rEI outside either the ±2 SD (11% of subjects) or ±1 SD (57% of subjects) cut-offs did not affect mean reported macronutrient intakes, but did markedly affect relationships between dietary composition and body mass index.

Conclusions:

When examining relationships between diet and health, use of ±1 SD cut-offs may be preferable to ±2 SD cut-offs for excluding inaccurate dietary reports.
Measuring food intake in studies of obesity
Authors: Lissner Lauren
Published: July 2003

The problem of how to measure habitual food intake in studies of obesity remains an enigma in nutritional research. The existence of obesity-specific underreporting was rather controversial until the advent of the doubly labelled water technique gave credence to previously anecdotal evidence that such a bias does in fact exist. This paper reviews a number of issues relevant to interpreting dietary data in studies involving obesity. Topics covered include: participation biases, normative biases, importance of matching method to study, selective underreporting, and a brief discussion of the potential implications of generalised and selective underreporting in analytical epidemiology. It is concluded that selective underreporting of certain food types by obese individuals would produce consequences in analytical epidemiological studies that are both unpredictable and complex. Since it is becoming increasingly acknowledged that selective reporting error does occur, it is important to emphasise that correction for energy intake is not sufficient to eliminate the biases from this type of error. This is true both for obesity-related selective reporting errors and more universal types of selective underreporting, e.g. foods of low social desirability. Additional research is urgently required to examine the consequences of this type of error.
Dietary Reference Intakes: summary of applications in dietary assessment
Authors: Murphy Suzanne P , Poos Mary I
Published: July 2003

Objective:

To summarise the applications and appropriate use of Dietary Reference Intakes (DRIs) as guidance for nutrition and health research professionals in the dietary assessment of groups and individuals.

Design:

Key points from the Institute of Medicine report, Dietary Reference Intakes: Applications in Dietary Assessment, are summarised in this paper. The different approaches for using DRIs to evaluate the intakes of groups vs. the intakes of individuals are highlighted.

Results:

Each of the new DRIs is defined and its role in the dietary assessment of groups and individuals is described. Two methods of group assessment and a new method for quantitative assessment of individuals are described. Illustrations are provided on appropriate use of the Estimated Average Requirement (EAR), the Adequate Intake (AI) and the Tolerable Upper Intake Level (UL) in dietary assessment.

Conclusions:

Dietary assessment of groups or individuals must be based on estimates of usual (long-term) intake. The EAR is the appropriate DRI to use in assessing groups and individuals. The AI is of limited value in assessing nutrient adequacy, and cannot be used to assess the prevalence of inadequacy. The UL is the appropriate DRI to use in assessing the proportion of a group at risk of adverse health effects. It is inappropriate to use the Recommended Dietary Allowance (RDA) or a group mean intake to assess the nutrient adequacy of groups.
Dietary assessment tools for developing countries for use in multi-centric, collaborative protocols
Authors: Solomons Noel W , Valdés-Ramos Roxana
Published: July 2003

In recent years, increasing interest in the format of multi-centric studies among different populations in developing nations has evolved in the field of health surveys and epidemiology. Dietary intake data are most often part of these cross-cultural and cross-national collaborative efforts. Various questions have been raised about the appropriate endeavours for dietetics and nutritional sciences in developing societies, the instruments available for application, and the pitfalls and caveats in their use. An important consideration is that studies be hypothesis-driven and not mere ‘fishing expeditions’ of unfocused data gathering. All known dietary intake measurement tools are within the purview of developing country research, but they often must be adapted individually and differentially to suit a given population. In a multi-centric context, this is complicated. The watchword should be collecting comparable information across sites, not using identical approaches. Choice of dietary intake measurement tools must be honed to the hypotheses and assumptions, on the one hand, and the exigencies and pitfalls of working in the developing country milieu, in which linguistics, seasonality, migration, uncommonness of food systems and ethical considerations present barriers and caveats, on the other. Within the hypotheses, the assumptions regarding the penetration of the measured exposures must be borne in mind. Multi-centre studies in developing countries have relevance and importance in the context of food security, diet and disease, eating behaviour and satiety regulation, and nutritional anthropology.
Biomarkers and the measurement of fatty acids
Authors: Arab Lenore , Akbar Jabar
Published: July 2003

Objective:

To review the various biomarkers of dietary intakes of fatty acids in human populations, their measurement, limitations and analytical considerations.

Design:

Review of the literature.

Results:

Although there is no good biomarker of intake of total fat, a number of alternatives exist for assessing the intakes of exogenously produced fatty acids that are consumed. Adipose tissue, erythrocyte membrane concentrations and serum or plasma levels can reflect prior intakes over the past few hours to the past few years. The concentrations of individual fatty acids in these media generally reflect relative levels, and are influenced by a number of factors. Although relatively expensive to analyse, a single analysis by gas chromatography or high-performance liquid chromatography provides information on multiple fatty acids, and is superior to attempting to measure specific fatty acids using traditional dietary assessment methods.

Conclusions:

Biomarkers of fatty acids that reflect long-term intake are available for nutritional epidemiology purposes. Analytical methods have become very accurate and able to detect and quantify smaller families, such as trans-fatty acids.
Homer 2 tunes G protein–coupled receptors stimulus intensity by regulating RGS proteins and PLCβ GAP activities
Authors: Shin Dong Min , Dehoff Marlin , Luo Xiang , Kang Shin Hyeok , Tu Jiangchen , Nayak Surendra K. , Ross Elliott M. , Worley Paul F. , Muallem Shmuel
Published: July 2003

Homers are scaffolding proteins that bind G protein–coupled receptors (GPCRs), inositol 1,4,5-triphosphate (IP3) receptors (IP3Rs), ryanodine receptors, and TRP channels. However, their role in Ca2+ signaling in vivo is not known. Characterization of Ca2+ signaling in pancreatic acinar cells from Homer2−/− and Homer3−/− mice showed that Homer 3 has no discernible role in Ca2+ signaling in these cells. In contrast, we found that Homer 2 tunes intensity of Ca2+ signaling by GPCRs to regulate the frequency of [Ca2+]i oscillations. Thus, deletion of Homer 2 increased stimulus intensity by increasing the potency for agonists acting on various GPCRs to activate PLCβ and evoke Ca2+ release and oscillations. This was not due to aberrant localization of IP3Rs in cellular microdomains or IP3R channel activity. Rather, deletion of Homer 2 reduced the effectiveness of exogenous regulators of G proteins signaling proteins (RGS) to inhibit Ca2+ signaling in vivo. Moreover, Homer 2 preferentially bound to PLCβ in pancreatic acini and brain extracts and stimulated GAP activity of RGS4 and of PLCβ in an in vitro reconstitution system, with minimal effect on PLCβ-mediated PIP2 hydrolysis. These findings describe a novel, unexpected function of Homer proteins, demonstrate that RGS proteins and PLCβ GAP activities are regulated functions, and provide a molecular mechanism for tuning signal intensity generated by GPCRs and, thus, the characteristics of [Ca2+]i oscillations.
Activity of Rho-family GTPases during cell division as visualized with FRET-based probes
Authors: Yoshizaki Hisayoshi , Ohba Yusuke , Kurokawa Kazuo , Itoh Reina E. , Nakamura Takeshi , Mochizuki Naoki , Nagashima Kazuo , Matsuda Michiyuki
Published: July 2003

Rho-family GTPases regulate many cellular functions. To visualize the activity of Rho-family GTPases in living cells, we developed fluorescence resonance energy transfer (FRET)–based probes for Rac1 and Cdc42 previously (Itoh, R.E., K. Kurokawa, Y. Ohba, H. Yoshizaki, N. Mochizuki, and M. Matsuda. 2002. Mol. Cell. Biol. 22:6582–6591). Here, we added two types of probes for RhoA. One is to monitor the activity balance between guanine nucleotide exchange factors and GTPase-activating proteins, and another is to monitor the level of GTP-RhoA. Using these FRET probes, we imaged the activities of Rho-family GTPases during the cell division of HeLa cells. The activities of RhoA, Rac1, and Cdc42 were high at the plasma membrane in interphase, and decreased rapidly on entry into M phase. From after anaphase, the RhoA activity increased at the plasma membrane including cleavage furrow. Rac1 activity was suppressed at the spindle midzone and increased at the plasma membrane of polar sides after telophase. Cdc42 activity was suppressed at the plasma membrane and was high at the intracellular membrane compartments during cytokinesis. In conclusion, we could use the FRET-based probes to visualize the complex spatio-temporal regulation of Rho-family GTPases during cell division.
QSulf1 remodels the 6-O sulfation states of cell surface heparan sulfate proteoglycans to promote Wnt signaling
Authors: Ai Xingbin , Do Anh-Tri , Lozynska Olga , Kusche-Gullberg Marion , Lindahl Ulf , Emerson Charles P.
Published: July 2003

The 6-O sulfation states of cell surface heparan sulfate proteoglycans (HSPGs) are dynamically regulated to control the growth and specification of embryonic progenitor lineages. However, mechanisms for regulation of HSPG sulfation have been unknown. Here, we report on the biochemical and Wnt signaling activities of QSulf1, a novel cell surface sulfatase. Biochemical studies establish that QSulf1 is a heparan sulfate (HS) 6-O endosulfatase with preference, in particular, toward trisulfated IdoA2S-GlcNS6S disaccharide units within HS chains. In cells, QSulf1 can function cell autonomously to remodel the sulfation of cell surface HS and promote Wnt signaling when localized either on the cell surface or in the Golgi apparatus. QSulf1 6-O desulfation reduces XWnt binding to heparin and HS chains of Glypican1, whereas heparin binds with high affinity to XWnt8 and inhibits Wnt signaling. CHO cells mutant for HS biosynthesis are defective in Wnt-dependent Frizzled receptor activation, establishing that HS is required for Frizzled receptor function. Together, these findings suggest a two-state “catch or present” model for QSulf1 regulation of Wnt signaling in which QSulf1 removes 6-O sulfates from HS chains to promote the formation of low affinity HS–Wnt complexes that can functionally interact with Frizzled receptors to initiate Wnt signal transduction.
Rho activation patterns after spinal cord injury and the role of activated Rho in apoptosis in the central nervous system
Authors: Dubreuil Catherine I. , Winton Matthew J. , McKerracher Lisa
Published: July 2003

Growth inhibitory proteins in the central nervous system (CNS) block axon growth and regeneration by signaling to Rho, an intracellular GTPase. It is not known how CNS trauma affects the expression and activation of RhoA. Here we detect GTP-bound RhoA in spinal cord homogenates and report that spinal cord injury (SCI) in both rats and mice activates RhoA over 10-fold in the absence of changes in RhoA expression. In situ Rho-GTP detection revealed that both neurons and glial cells showed Rho activation at SCI lesion sites. Application of a Rho antagonist (C3–05) reversed Rho activation and reduced the number of TUNEL-labeled cells by ∼50% in both injured mouse and rat, showing a role for activated Rho in cell death after CNS injury. Next, we examined the role of the p75 neurotrophin receptor (p75NTR) in Rho signaling. After SCI, an up-regulation of p75NTR was detected by Western blot and observed in both neurons and glia. Treatment with C3–05 blocked the increase in p75NTR expression. Experiments with p75NTR-null mutant mice showed that immediate Rho activation after SCI is p75NTR dependent. Our results indicate that blocking overactivation of Rho after SCI protects cells from p75NTR-dependent apoptosis.
Polyamines play a critical role in the control of the innate immune response in the mouse central nervous system
Authors: Soulet Denis , Rivest Serge
Published: July 2003

The present work investigated whether polyamines play a role in the control of the innate immune response in the brain. The first evidence that these molecules may be involved in such a process was based on the robust increase in the expression of the first and rate-limiting enzyme of biosynthesis of polyamines during immune stimuli. Indeed, systemic lipopolysaccharide (LPS) administration increased ornithine decarboxylase (ODC) mRNA and protein within neurons and microglia across the mouse central nervous system (CNS). This treatment was also associated with a robust and transient transcriptional activation of genes encoding pro-inflammatory cytokines and toll-like receptor 2 (TLR2) in microglial cells. The endotoxin increased the cerebral activity of ODC, which was abolished by a suicide inhibitor of ODC. The decrease in putrescine levels largely prevented the ability of LPS to trigger tumor necrosis factor α and TLR2 gene transcription in the mouse brain. In contrast, expression of both transcripts was clearly exacerbated in response to intracerebral spermine infusion. Finally, inhibition of polyamine synthesis abolished neurodegeneration and increased the survival rate of mice exposed to a model of severe innate immune reaction in the CNS. Thus, polyamines have a major impact on the neuronal integrity and cerebral homeostasis during immune insults.
Identification of synaptotagmin effectors via acute inhibition of secretion from cracked PC12 cells
Authors: Tucker Ward C. , Edwardson J. Michael , Bai Jihong , Kim Hyun-Jung , Martin Thomas F.J. , Chapman Edwin R.
Published: July 2003

T he synaptotagmins (syts) are a family of membrane proteins proposed to regulate membrane traffic in neuronal and nonneuronal cells. In neurons, the Ca2+-sensing ability of syt I is critical for fusion of docked synaptic vesicles with the plasma membrane in response to stimulation. Several putative Ca2+–syt effectors have been identified, but in most cases the functional significance of these interactions remains unknown. Here, we have used recombinant C2 domains derived from the cytoplasmic domains of syts I–XI to interfere with endogenous syt–effector interactions during Ca2+-triggered exocytosis from cracked PC12 cells. Inhibition was closely correlated with syntaxin–SNAP-25 and phosphatidylinositol 4,5-bisphosphate (PIP2)–binding activity. Moreover, we measured the expression levels of endogenous syts in PC12 cells; the major isoforms are I and IX, with trace levels of VII. As expected, if syts I and IX function as Ca2+ sensors, fragments from these isoforms blocked secretion. These data suggest that syts trigger fusion via their Ca2+-regulated interactions with t-SNAREs and PIP2, target molecules known to play critical roles in exocytosis.
Epstein-Barr virus LMP1 blocks p16INK4a–RB pathway by promoting nuclear export of E2F4/5
Authors: Ohtani Naoko , Brennan Paul , Gaubatz Stefan , Sanij Elaine , Hertzog Paul , Wolvetang Ernst , Ghysdael Jacques , Rowe Martin , Hara Eiji
Published: July 2003

The p16INK4a–RB pathway plays a critical role in preventing inappropriate cell proliferation and is often targeted by viral oncoproteins during immortalization. Latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) is often present in EBV-associated proliferative diseases and is critical for the immortalizing and transforming activity of EBV. Unlike other DNA tumor virus oncoproteins, which possess immortalizing activity, LMP1 does not bind to retinoblastoma tumor suppressor protein, but instead blocks the expression of p16INK4a tumor suppressor gene. However, it has been unclear how LMP1 represses the p16INK4a gene expression. Here, we report that LMP1 promotes the CRM1-dependent nuclear export of Ets2, which is an important transcription factor for p16INK4a gene expression, thereby reducing the level of p16INK4a expression. We further demonstrate that LMP1 also blocks the function of E2F4 and E2F5 (E2F4/5) transcription factors through promoting their nuclear export in a CRM1-dependent manner. As E2F4/5 are essential downstream mediators for a p16INK4a-induced cell cycle arrest, these results indicate that the action of LMP1 on nuclear export has two effects on the p16INK4a–RB pathway: (1) repression of p16INK4a expression and (2) blocking the downstream mediator of the p16INK4a–RB pathway. These results reveal a novel activity of LMP1 and increase an understanding of how viral oncoproteins perturb the p16INK4a–RB pathway.
Critical roles for the COOH-terminal NITY and RGT sequences of the integrin β3 cytoplasmic domain in inside-out and outside-in signaling
Authors: Xi Xiaodong , Bodnar Richard J. , Li Zhenyu , Lam Stephen C.-T. , Du Xiaoping
Published: July 2003

Bidirectional signaling of integrin αIIbβ3 requires the β3 cytoplasmic domain. To determine the sequence in the β3 cytoplasmic domain that is critical to integrin signaling, cell lines were established that coexpress the platelet receptor for von Willebrand factor (vWF), glycoprotein Ib-IX, integrin αIIb, and mutants of β3 with truncations at sites COOH terminal to T741, Y747, F754, and Y759. Truncation at Y759 did not affect integrin activation, as indicated by vWF-induced fibrinogen binding, but affected cell spreading and stable adhesion. Thus, the COOH-terminal RGT sequence of β3 is important for outside-in signaling but not inside-out signaling. In contrast, truncation at F754, Y747, or T741 completely abolished integrin activation. A point mutation replacing Y759 with alanine also abolished integrin activation. Thus, the T755NITY759 sequence of β3, containing an NXXY motif, is critical to inside-out signaling, whereas the intact COOH terminus is important for outside-in signaling. In addition, we found that the calcium-dependent protease calpain preferentially cleaves at Y759 in a population of β3 during platelet aggregation and adhesion, suggesting that calpain may selectively regulate integrin outside-in signaling.
BCL6 Controls the Expression of the B7-1/CD80 Costimulatory Receptor in Germinal Center B Cells
Authors: Niu Huifeng , Cattoretti Giorgio , Dalla-Favera Riccardo
Published: July 2003

The BCL6 proto-oncogene encodes a transcriptional repressor required for the development of germinal centers (GCs) and implicated in the pathogenesis of GC-derived B cell lymphoma. Understanding the precise role of BCL6 in normal GC formation and in lymphomagenesis depends on the identification of genes that are direct targets of its transcriptional repression. Here we report that BCL6 directly controls the expression of B7–1/CD80, a costimulatory receptor involved in B–T cell interactions critical for the development of T cell–mediated antibody responses. Upon CD40 signaling, transcription of the CD80 gene is induced by the nuclear factor (NF)-κB transcription factor. Our results show that BCL6 prevents CD40-induced expression of CD80 by binding its promoter region in vivo and suppressing its transcriptional activation by NF-κB. Consistent with a physiologic role for BCL6 in suppressing CD80, the expression of these two genes is mutually exclusive in B cells, and BCL6-defective mice show increased expression of CD80 in B cells. The results suggest that BCL6 may directly control the ability of B cell to interact with T cells during normal GC development. In addition, these findings imply that T–B cell interactions may be disrupted in B cell lymphoma expressing deregulated BCL6 genes.
CD4+ T Cell Polarization in Mice Is Modulated by Strain-specific Major Histocompatibility Complex–independent Differences within Dendritic Cells
Authors: Filippi Christophe , Hugues Stéphanie , Cazareth Julie , Julia Valérie , Glaichenhaus Nicolas , Ugolini Sophie
Published: July 2003

Resistance and susceptibility to Leishmania major in mice are determined by multiple genes and correlate with the preferential development of Th1 and Th2 responses, respectively. Here, we found that CD11b+ dendritic cells (DCs) prime parasite-specific CD4+ T cells in both susceptible BALB/c (H2-d) and resistant B10.D2 (H2-d) mice. However, BALB/c and B10.D2 DCs from L. major–infected mice differ in their ability to polarize naive T cells into Th1 or Th2 effector cells. This difference is cell-intrinsic, is not restricted to H2-d mice, and is observed with both parasite-specific and allospecific CD4+ T cells. Thus, strain-specific differences within CD11b+ DCs influence the ability of inbred mice to mount polarized CD4+ T cell responses.
OX40 (CD134) Controls Memory T Helper 2 Cells that Drive Lung Inflammation
Authors: Salek-Ardakani Shahram , Song Jianxun , Halteman Beth S. , Jember Amha Gebre-Hiwot , Akiba Hisaya , Yagita Hideo , Croft Michael
Published: July 2003

Asthma is caused by memory Th2 cells that often arise early in life and persist after repeated encounters with allergen. Although much is known regarding how Th2 cells develop, there is little information about the molecules that regulate memory Th2 cells after they have formed. Here we show that the costimulatory molecule OX40 is expressed on memory CD4 cells. In already sensitized animals, blocking OX40–OX40L interactions at the time of inhalation of aerosolized antigen suppressed memory effector accumulation in lung draining lymph nodes and lung, and prevented eosinophilia, airway hyperreactivity, mucus secretion, and Th2 cyto-kine production. Demonstrating that OX40 signals directly regulate memory T cells, antigen-experienced OX40-deficient T cells were found to divide initially but could not survive and accumulate in large numbers after antigen rechallenge. Thus, OX40–OX40L interactions are pivotal to the efficiency of recall responses regulated by memory Th2 cells.
Differential Requirement for Mesenchyme in the Proliferation and Maturation of Thymic Epithelial Progenitors
Authors: Jenkinson William E. , Jenkinson Eric J. , Anderson Graham
Published: July 2003

Formation of a mature thymic epithelial microenvironment is an essential prerequisite for the generation of a functionally competent T cell pool. It is likely that recently identified thymic epithelial precursors undergo phases of proliferation and differentiation to generate mature cortical and medullary thymic microenvironments. The mechanisms regulating development of immature thymic epithelial cells are unknown. Here we provide evidence that expansion of embryonic thymic epithelium is regulated by the continued presence of mesenchyme. In particular, mesenchymal cells are shown to mediate thymic epithelial cell proliferation through their provision of fibroblast growth factors 7 and 10. In contrast, differentiation of immature thymic epithelial cells, including acquisition of markers of mature cortical and medullary epithelium, occurs in the absence of ongoing mesenchymal support. Collectively, our data define a role for mesenchymal cells in thymus development, and indicate distinct mechanisms regulate proliferation and differentiation of immature thymic epithelial cells. In addition, our findings may aid in studies aimed at developing strategies to enhance thymus reconstitution and functioning in clinical certain contexts where thymic epithelial cell function is perturbed.
Interleukin 1α Promotes Th1 Differentiation and Inhibits Disease Progression in Leishmania major–susceptible BALB/c Mice
Authors: von Stebut Esther , Ehrchen Jan M. , Belkaid Yasmine , Kostka Susanna Lopez , Mölle Katharina , Knop Jürgen , Sunderkötter Cord , Udey Mark C.
Published: July 2003

Protective immunity against pathogens such as Leishmania major is mediated by interleukin (IL)-12–dependent Th1-immunity. We have shown previously that skin-dendritic cells (DCs) from both resistant C57BL/6 and susceptible BALB/c mice release IL-12 when infected with L. major, and infected BALB/c DCs effectively vaccinate against leishmaniasis. To determine if cytokines other than IL-12 might influence disease outcome, we surveyed DCs from both strains for production of a variety of cytokines. Skin-DCs produced significantly less IL-1α in response to lipopolysaccharide/interferon γ or L. major when expanded from BALB/c as compared with C57BL/6 mice. In addition, IL-1α mRNA accumulation in lymph nodes of L. major–infected BALB/c mice was ∼3-fold lower than that in C57BL/6 mice. Local injections of IL-1α during the first 3 d after infection led to dramatic, persistent reductions in lesion sizes. In L. major–infected BALB/c mice, IL-1α administration resulted in increased Th1- and strikingly decreased Th2-cytokine production. IL-1α and IL-12 treatments were similarly effective, and IL-1α efficacy was strictly IL-12 dependent. These data indicate that transient local administration of IL-1α acts in conjunction with IL-12 to influence Th-development in cutaneous leishmaniasis and prevents disease progression in susceptible BALB/c mice, perhaps by enhancing DC-induced Th1-education. Differential production of IL-1 by C57BL/6 and BALB/c mice may provide a partial explanation for the disparate outcomes of infection in these mouse strains.
Mutation in Fas Ligand Impairs Maturation of Thymocytes Bearing Moderate Affinity T Cell Receptors
Authors: Boursalian Tamar E. , Fink Pamela J.
Published: July 2003

Fas ligand, best known as a death-inducer, is also a costimulatory molecule required for maximal proliferation of mature antigen-specific CD4+ and CD8+ T cells. We now extend the role of Fas ligand by showing that it can also influence thymocyte development. T cell maturation in some, but not all, strains of TCR transgenic mice is severely impaired in thymocytes expressing mutant Fas ligand incapable of interacting with Fas. Mutant Fas ligand inhibits neither negative selection nor death by neglect. Instead, it appears to modulate positive selection of thymocytes expressing both class I– and class II–restricted T cell receptors of moderate affinity for their positively selecting ligands. Fas ligand is therefore an inducer of death, a costimulator of peripheral T cell activation, and an accessory molecule in positive selection.
Identification of Store-independent and Store-operated Ca2+ Conductances inCaenorhabditis elegansIntestinal Epithelial Cells
Authors: Estevez Ana Y. , Roberts Randolph K. , Strange Kevin
Published: July 2003

The nematode Caenorhabditis elegans offers significant experimental advantages for defining the genetic basis of diverse biological processes. Genetic and physiological analyses have demonstrated that inositol-1,4,5-trisphosphate (IP3)–dependent Ca2+ oscillations in intestinal epithelial cells play a central role in regulating the nematode defecation cycle, an ultradian rhythm with a periodicity of 45–50 s. Patch clamp studies combined with behavioral assays and forward and reverse genetic screening would provide a powerful approach for defining the molecular details of oscillatory Ca2+ signaling. However, electrophysiological characterization of the intestinal epithelium has not been possible because of its relative inaccessibility. We developed primary intestinal epithelial cell cultures that circumvent this problem. Intestinal cells express two highly Ca2+-selective, voltage-independent conductances. One conductance, IORCa, is constitutively active, exhibits strong outward rectification, is 60–70-fold more selective for Ca2+ than Na+, is inhibited by intracellular Mg2+ with a K1/2 of 692 μM, and is insensitive to Ca2+ store depletion. Inhibition of IORCa with high intracellular Mg2+ concentrations revealed the presence of a small amplitude conductance that was activated by passive depletion of intracellular Ca2+ stores. Active depletion of Ca2+ stores with IP3 or ionomycin increased the rate of current activation ∼8- and ∼22-fold compared with passive store depletion. The store-operated conductance, ISOC, exhibits strong inward rectification, and the channel is highly selective for Ca2+ over monovalent cations with a divalent cation selectivity sequence of Ca2+ > Ba2+ ≈ Sr2+. Reversal potentials for ISOC could not be detected accurately between 0 and +80 mV, suggesting that PCa/PNa of the channel may exceed 1,000:1. Lanthanum, SKF 96365, and 2-APB inhibit both IORCa and ISOC reversibly. Our studies provide the first detailed electrophysiological characterization of voltage-independent Ca2+ conductances in C. elegans and form the foundation for ongoing genetic and molecular studies aimed at identifying the genes that encode the intestinal cell channels, for defining mechanisms of channel regulation and for defining their roles in oscillatory Ca2+ signaling.
Role of TASK2 Potassium Channels Regarding Volume Regulation in Primary Cultures of Mouse Proximal Tubules
Authors: Barriere Herve , Belfodil Radia , Rubera Isabelle , Tauc Michel , Lesage Florian , Poujeol Chantal , Guy Nicolas , Barhanin Jacques , Poujeol Philippe
Published: July 2003

Several papers reported the role of TASK2 channels in cell volume regulation and regulatory volume decrease (RVD). To check the possibility that the TASK2 channel modulates the RVD process in kidney, we performed primary cultures of proximal convoluted tubules (PCT) and distal convoluted tubules (DCT) from wild-type and TASK2 knockout (KO) mice. In KO mice, the TASK2 coding sequence was in part replaced by the lac-Z gene. This allows for the precise localization of TASK2 in kidney sections using β-galactosidase staining. TASK2 was only localized in PCT cells. K+ currents were analyzed by the whole-cell clamp technique with 125 mM K-gluconate in the pipette and 140 mM Na-gluconate in the bath. In PCT cells from wild-type mice, hypotonicity induced swelling-activated K+ currents insensitive to 1 mM tetraethylammonium, 10 nM charybdotoxin, and 10 μM 293B, but blocked by 500 μM quinidine and 10 μM clofilium. These currents were increased in alkaline pH and decreased in acidic pH. In PCT cells from TASK2 KO, swelling-activated K+ currents were completely impaired. In conclusion, the TASK2 channel is expressed in kidney proximal cells and could be the swelling-activated K+ channel responsible for the cell volume regulation process during osmolyte absorptions in the proximal tubules.
The Rate of Information Transfer of Naturalistic Stimulation by Graded Potentials
Authors: Juusola Mikko , de Polavieja Gonzalo G.
Published: July 2003

We present a method to measure the rate of information transfer for any continuous signals of finite duration without assumptions. After testing the method with simulated responses, we measure the encoding performance of Calliphora photoreceptors. We find that especially for naturalistic stimulation the responses are nonlinear and noise is nonadditive, and show that adaptation mechanisms affect signal and noise differentially depending on the time scale, structure, and speed of the stimulus. Different signaling strategies for short- and long-term and dim and bright light are found for this graded system when stimulated with naturalistic light changes.
Sizing the Protein Translocation Pathway of Colicin Ia Channels
Authors: Kienker Paul K. , Jakes Karen S. , Blaustein Robert O. , Miller Christopher , Finkelstein Alan
Published: July 2003

The bacterial toxin colicin Ia forms voltage-gated channels in planar lipid bilayers. The toxin consists of three domains, with the carboxy-terminal domain (C-domain) responsible for channel formation. The C-domain contributes four membrane-spanning segments and a 68-residue translocated segment to the open channel, whereas the upstream domains and the amino-terminal end of the C-domain stay on the cis side of the membrane. The isolated C-domain, lacking the two upstream domains, also forms channels; however, the amino terminus and one of the normally membrane-spanning segments can move across the membrane. (This can be observed as a drop in single-channel conductance.) In longer carboxy-terminal fragments of colicin Ia that include ≤169 residues upstream from the C-domain, the entire upstream region is translocated. Presumably, a portion of the C-domain creates a pathway for the polar upstream region to move through the membrane. To determine the size of this translocation pathway, we have attached “molecular stoppers,” small disulfide-bonded polypeptides, to the amino terminus of the C-domain, and determined whether they could be translocated. We have found that the translocation rate is strongly voltage dependent, and that at voltages ≥90 mV, even a 26-Å stopper is translocated. Upon reduction of their disulfide bonds, all of the stoppers are easily translocated, indicating that it is the folded structure, rather than some aspect of the primary sequence, that slows translocation of the stoppers. Thus, the pathway for translocation is ≥26 Å in diameter, or can stretch to this value. This is large enough for an α-helical hairpin to fit through.
Looking Back: Exploring the Psychology of Queuing and the Effect of the Number of People Behind
Authors: Zhou Rongrong , Soman Dilip
Published: July 2003

Queues are a ubiquitous phenomenon. This research investigates consumers' affective experiences in a queue and their decisions to leave the queue after having spent some time in it (reneging). In particular, we find in our first two studies that, as the number of people behind increases, the consumer is in a relatively more positive affective state and the likelihood of reneging is lower. While a number of explanations may account for this effect, we focus on the role of social comparisons. In particular, we expect consumers in a queue to make downward comparisons with the less fortunate others behind them. We propose that three types of factors influence the degree of social comparisons made and thus moderate the effect of the number behind: (a) queue factors that influence the ease with which social comparisons can be made, (b) individual factors that determine the personal tendency to make social comparisons, and (c) situational factors that influence the degree of social comparisons through the generation of counterfactuals. Across three studies, we find support for each moderating effect. We conclude with a discussion on theoretical implications and limitations, and we propose avenues for future research.
Distinguishing properties of weak slice conditions
Authors: Buckley Stephen , Stanoyevitch Alexander
Published: July 2003

The slice condition and the more general weak slice conditions are geometric conditions on Euclidean space domains which have evolved over the last several years as a tool in various areas of analysis. This paper explores some of the finer distinctive properties of the various weak slice conditions.
Rabring7, a Novel Rab7 Target Protein with a RING Finger Motif
Authors: Mizuno Kouichi , Kitamura Akiko , Sasaki Takuya
Published: July 2003

Rab7, a member of the Rab family small G proteins, has been shown to regulate intracellular vesicle traffic to late endosome/lysosome and lysosome biogenesis, but the exact roles of Rab7 are still undetermined. Accumulating evidence suggests that each Rab protein has multiple target proteins that function in the exocytic/endocytic pathway. We have isolated a new Rab7 target protein, Rabring7 (Rab7-interacting RING finger protein), using a CytoTrap system. It contains an H2 type RING finger motif at the C termini. Rabring7 shows no homology with RILP, which has been reported as another Rab7 target protein. GST pull-down and coimmunoprecipitation assays demonstrate that Rabring7 specifically binds the GTP-bound form of Rab7 at the N-terminal portion. Rabring7 is found mainly in the cytosol and is recruited efficiently to late endosomes/lysosomes by the GTP-bound form of Rab7 in BHK cells. Overexpression of Rabring7 not only affects epidermal growth factor degradation but also causes the perinuclear aggregation of lysosomes, in which the accumulation of the acidotropic probe LysoTracker is remarkably enhanced. These results suggest that Rabring7 plays crucial roles as a Rab7 target protein in vesicle traffic to late endosome/lysosome and lysosome biogenesis.
Expression of Phosphatidylinositol (4,5) Bisphosphate–specific Pleckstrin Homology Domains Alters Direction But Not the Level of Axonal Transport of Mitochondria
Authors: De Vos Kurt J. , Sable Julia , Miller Kyle E. , Sheetz Michael P.
Published: July 2003

Axonal transport of membranous organelles such as mitochondria is essential for neuron viability and function. How signaling mechanisms regulate or influence mitochondrial distribution and transport is still largely unknown. We observed an increase in the distal distribution of mitochondria in neurons upon the expression of pleckstrin homology (PH) domains of phospholipase Cδ1 (PLCδ-PH) and spectrin (spectrin-PH). Quantitative analysis of mitochondrial transport showed that specific binding of PH domains to phosphatidylinositol (4,5) bisphosphate (PtdIns(4,5)P2) but not 3′ phosphorylated phosphatidylinositol species enhanced plus-end–directed transport of mitochondria two- to threefold and at the same time decreased minus-end–directed transport of mitochondria along axonal microtubules (MTs) without altering the overall level of motility. Further, the velocity and duration of mitochondrial transport plus the association of molecular motors with mitochondria remained unchanged by the expression of PH domains. Thus, PtdIns(4,5)P2-specific PH domains caused an increase in distal mitochondria by disturbing the balance of plus- and minus-end–directed transport rather than directly affecting the molecular machinery involved. Taken together our data reveal that level and directionality of transport are separable and that PtdIns(4,5)P2 has a novel role in regulation of the directionality of axonal transport of mitochondria.
Part of Ran Is Associated with AKAP450 at the Centrosome: Involvement in Microtubule-organizing Activity
Authors: Keryer Guy , Di Fiore Barbara , Celati Claude , Lechtreck Karl Ferdinand , Mogensen Mette , Delouvée Annie , Lavia Patrizia , Bornens Michel , Tassin Anne-Marie
Published: July 2003

The small Ran GTPase, a key regulator of nucleocytoplasmic transport, is also involved in microtubule assembly and nuclear membrane formation. Herein, we show by immunofluorescence, immunoelectron microscopy, and biochemical analysis that a fraction of Ran is tightly associated with the centrosome throughout the cell cycle. Ran interaction with the centrosome is mediated by the centrosomal matrix A kinase anchoring protein (AKAP450). Accordingly, when AKAP450 is delocalized from the centrosome, Ran is also delocalized, and as a consequence, microtubule regrowth or anchoring is altered, despite the persisting association of γ-tubulin with the centrosome. Moreover, Ran is recruited to Xenopus sperm centrosome during its activation for microtubule nucleation. We also demonstrate that centrosomal proteins such as centrin and pericentrin, but not γ-tubulin, AKAP450, or ninein, undertake a nucleocytoplasmic exchange as they concentrate in the nucleus upon export inhibition by leptomycin B. Together, these results suggest a challenging possibility, namely, that centrosome activity could depend upon nucleocytoplasmic exchange of centrosomal proteins and local Ran-dependent concentration at the centrosome.
The GTP-binding Protein RhoA Mediates Na,K-ATPase Exocytosis in Alveolar Epithelial Cells
Authors: Lecuona Emilia , Ridge Karen , Pesce Liuska , Batlle Daniel , Sznajder Jacob I.
Published: July 2003

The purpose of this study was to define the role of the Rho family of small GTPases in the β-adrenergic regulation of the Na,K-ATPase in alveolar epithelial cells (AEC). The β-adrenergic receptor agonist isoproterenol (ISO) increased the Na,K-ATPase protein abundance at the plasma membrane and activated RhoA in a time-dependent manner. AEC pretreated with mevastatin, a specific inhibitor of prenylation, or transfected with the dominant negative RhoAN19, prevented ISO-mediated Na,K-ATPase exocytosis to the plasma membrane. The ISO-mediated activation of RhoA in AEC occurred via β2-adrenergic receptors and involved Gs-PKA as demonstrated by incubation with the protein kinase A (PKA)-specific inhibitors H89 and PKI (peptide specific inhibitor), and Gi, as incubation with pertussis toxin or cells transfected with a minigene vector for Giinhibited the ISO-mediated RhoA activation. However, cells transfected with minigene vectors for G12and G13did not prevent RhoA activation by ISO. Finally, the ISO-mediated Na,K-ATPase exocytosis was regulated by the Rho-associated kinase (ROCK), as preincubation with the specific inhibitor Y-27632 or transfection with dominant negative ROCK, prevented the increase in Na,K-ATPase at the plasma membrane. Accordingly, ISO regulates Na,K-ATPase exocytosis in AEC via the activation of β2-adrenergic receptor, Gs, PKA, Gi, RhoA, and ROCK.