bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic review of associations between environmental factors, energy and fat intakes among adults: is there evidence for environments that encourage obesogenic dietary intakes?
Authors: Giskes Katrina , Kamphuis Carlijn BM , van Lenthe Frank J , Kremers Stef , Droomers Mariel , Brug Johannes
Published: February 2007

Objective

To review the literature examining associations between environmental factors, energy and fat intakes among adults, and to identify issues for future research.

Methods

Literature searches of studies published between 1980 and 2004 were conducted in major databases (i.e. PubMed, Human Nutrition, Web of Science, PsychInfo, Sociofile). Additional articles were located by citation tracking.

Results

Twenty-one articles met the inclusion criteria. No study provided a clear conceptualisation of how environmental factors may influence these dietary intakes. Availability, social, cultural and material aspects of the environment were relatively understudied compared with other factors such as seasonal/day of the week variation and work-related factors. Few studies examined the specific environmental factors implicated in the obesity epidemic, and there was little study replication. All studies were observational and cross-sectional.

Conclusions

It is too premature to conclude whether or not environmental factors play a role in obesogenic and unhealthy dietary intakes. More studies need to examine associations with those environmental factors thought to contribute to obesogenic environments. There needs to be more development in theories that conceptualise the relationship between environmental factors and dietary intakes.
Remaining challenges in Tanzania's efforts to eliminate iodine deficiency
Authors: Assey Vincent D , Mgoba Celestin , Mlingi Nicholaus , Sanga Alfred , Ndossi Godwin D , Greiner Ted , Peterson Stefan
Published: February 2007

Objective

To determine iodine levels in salt and iodine deficiency prevalence in school-aged children in 16 districts in Tanzania with previous severe iodine deficiency.

Design

A cross-sectional study in schoolchildren. Systematic probability sampling was used to select schools and subjects for goitre assessment and urinary iodine determination.

Setting

Sixteen districts randomly selected from the 27 categorised as severely iodine-deficient in Tanzania.

Subjects

The study population was primary-school children aged 6–18 years who were examined for goitre prevalence and urinary iodine concentration (UIC). Salt samples from schoolchildren's homes and from shops were tested for iodine content.

Results

The study revealed that 83.3% of households (n = 21 160) in the surveyed districts used iodised salt. Also, 94% of sampled shops (n = 397) sold iodised salt, with a median iodine level of 37.0 ppm (range 4.2–240 ppm). Median UIC in 2089 schoolchildren was 235.0 μg l− 1and 9.3% had UIC values below 50 μg l− 1. The overall unweighted mean visible and total goitre prevalence was 6.7% and 24.3%, respectively (n = 16 222). The age group 6–12 years had the lowest goitre prevalence (3.6% visible and 18.0% total goitre,n = 7147). The total goitre prevalence had decreased significantly in all districts from an unweighted mean of 65.4% in the 1980s to 24.3% in 1999 (P < 0.05). We believe this difference was also biologically significant.

Conclusion

These findings indicate that iodine deficiency is largely eliminated in the 16 districts categorised as severely iodine-deficient in Tanzania, and that the iodine content of salt purchased from shops is highly variable.
Optically pumped GaN∕AlGaN separate-confinement heterostructure laser grown along the (112¯0) nonpolar direction
Authors: Teisseyre H. , Skierbiszewski C. , Khachapuridze A. , Feduniewicz-Żmuda A. , Siekacz M. , £ucznik B. , Kamler G. , Kryśko M. , Suski T. , Perlin P. , Grzegory I. , Porowski S.
Published: February 2007

This letter concerns experiments on optically pumped GaN∕AlGaN separate-confinement heterostructure laser structures grown by plasma assisted molecular beam epitaxy. The structures were grown along the (112¯0) nonpolar crystallographic direction on a bulk GaN substrate. Different widths of GaN quantum wells were applied in the studied structures. Laser action is clearly demonstrated by the spontaneous emission saturation, abrupt line narrowing, and strong TE polarization of output light. A lasing threshold was reached at an excitation power density of 260kW∕cm2 for a 700-μm-long cavity at room temperature.
Compensatory dynamics are rare in natural ecological communities
Authors: Houlahan J. E. , Currie D. J. , Cottenie K. , Cumming G. S. , Ernest S. K. M. , Findlay C. S. , Fuhlendorf S. D. , Gaedke U. , Legendre P. , Magnuson J. J. , McArdle B. H. , Muldavin E. H. , Noble D. , Russell R. , Stevens R. D. , Willis T. J. , Woiwod I. P. , Wondzell S. M.
Published: February 2007

In population ecology, there has been a fundamental controversy about the relative importance of competition-driven (density-dependent) population regulation vs. abiotic influences such as temperature and precipitation. The same issue arises at the community level; are population sizes driven primarily by changes in the abundances of cooccurring competitors (i.e., compensatory dynamics), or do most species have a common response to environmental factors? Competitive interactions have had a central place in ecological theory, dating back to Gleason, Volterra, Hutchison and MacArthur, and, more recently, Hubbell's influential unified neutral theory of biodiversity and biogeography. If competitive interactions are important in driving year-to-year fluctuations in abundance, then changes in the abundance of one species should generally be accompanied by compensatory changes in the abundances of others. Thus, one necessary consequence of strong compensatory forces is that, on average, species within communities will covary negatively. Here we use measures of community covariance to assess the prevalence of negative covariance in 41 natural communities comprising different taxa at a range of spatial scales. We found that species in natural communities tended to covary positively rather than negatively, the opposite of what would be expected if compensatory dynamics were important. These findings suggest that abiotic factors such as temperature and precipitation are more important than competitive interactions in driving year-to-year fluctuations in species abundance within communities.
The strange case of the earliest silver extraction by European colonists in the New World
Authors: Thibodeau A. M. , Killick D. J. , Ruiz J. , Chesley J. T. , Deagan K. , Cruxent J. M. , Lyman W.
Published: February 2007

La Isabela, the first European town in the New World, was established in 1494 by the second expedition of Christopher Columbus but was abandoned by 1498. The main motive for settlement was to find and exploit deposits of precious metals. Archaeological evidence of silver extraction at La Isabela seemed to indicate that the expedition had located and tested deposits of silver-bearing lead ore in the Caribbean. Lead isotope analysis refutes this hypothesis but provides new evidence of the desperation of the inhabitants of La Isabela just before its abandonment.
Methionine transmethylation and transsulfuration in the piglet gastrointestinal tract
Authors: Riedijk Maaike A. , Stoll Barbara , Chacko Shaji , Schierbeek Henk , Sunehag Agneta L. , van Goudoever Johannes B. , Burrin Douglas G.
Published: February 2007

Methionine is an indispensable sulfur amino acid that functions as a key precursor for the synthesis of homocysteine and cysteine. Studies in adult humans suggest that splanchnic tissues convert dietary methionine to homocysteine and cysteine by means of transmethylation and transsulfuration, respectively. Studies in piglets show that significant metabolism of dietary indispensable amino acids occurs in the gastrointestinal tissues (GIT), yet the metabolic fate of methionine in GIT is unknown. We show here that 20% of the dietary methionine intake is metabolized by the GIT in piglets implanted with portal and arterial catheters and fed milk formula. Based on analyses from intraduodenal and intravenous infusions of [1-13C]methionine and [2H3]methionine, we found that the whole-body methionine transmethylation and remethylation rates were significantly higher during duodenal than intravenous tracer infusion. First-pass splanchnic metabolism accounted for 18% and 43% of the whole-body transmethylation and remethylation, respectively. Significant transmethylation and transsulfuration was demonstrated in the GIT, representing ≈27% and ≈23% of whole-body fluxes, respectively. The methionine used by the GIT was metabolized into homocysteine (31%), CO2(40%), or tissue protein (29%). Cystathionine β-synthase mRNA and activity was present in multiple GITs, including intestinal epithelial cells, but was significantly lower than liver. We conclude that the GIT consumes 20% of the dietary methionine and is a significant site of net homocysteine production. Moreover, the GITs represent a significant site of whole-body transmethylation and transsulfuration, and these two pathways account for a majority of methionine used by the GITs.
Confirmation of Neanderthal/modern human interstratification at the Chatelperronian type-site
Authors: Mellars Paul , Gravina Brad , Bronk Ramsey Christopher
Published: February 2007

The nature of the replacement of Neanderthal by anatomically and behaviorally modern populations in Europe is currently a topic of lively debate in human evolution. In an earlier paper [Gravina B, Mellars P, Bronk Ramsey C (2005)
Nature
483:51–56], we published a series of radiocarbon accelerator mass spectrometer measurements for the site of Châtelperron in central France, which had been claimed to show a clear “interstratification” of successive levels of Neanderthal and modern human occupation, on the basis of excavations carried out by Henri Delporte in the 1950s. This interpretation has recently been challenged by Zilhão and colleagues [Zilhão J, d'Errico F, Bordes J-G, Lenoble A, Texier J-P, Rigaud J-P (2006)
Proc Natl Acad Sci USA
103:12643–12648], who suggest that the deposits excavated in the 1950s consisted largely, if not entirely, of the unstratified “backdirt” of the earlier, 19th century excavations on the site. We show here that the excavation backdirt interpretation for the Châtelperron stratigraphy can be refuted from many different aspects of the stratigraphic, radiocarbon, and archaeological evidence. We reassess the significance of this site for current models of the coexistence and interactions between Neanderthal and anatomically modern populations in western Europe.
Interaction between transcellular and paracellular water transport pathways through Aquaporin 5 and the tight junction complex
Authors: Kawedia Jitesh D. , Nieman Michelle L. , Boivin Gregory P. , Melvin James E. , Kikuchi Ken-Ichiro , Hand Arthur R. , Lorenz John N. , Menon Anil G.
Published: February 2007

To investigate potential physiological interactions between the transcellular and paracellular pathways of water transport, we asked whether targeted deletion of Aquaporin 5 (AQP5), the major transcellular water transporter in salivary acinar cells, affected paracellular transport of 4-kDa FITC-labeled dextran (FITC-D), which is transported through the paracellular but not the transcellular route. After i.v. injection of FITC-D into either AQP5 wild-type or AQP5−/− mice and saliva collection for fixed time intervals, we show that the relative amount of FITC-D transported in the saliva of AQP5−/− mice is half that in matched AQP5+/+ mice, indicating a 2-fold decrease in permeability of the paracellular barrier in mice lacking AQP5. We also found a significant difference in the proportion of transcellular vs. paracellular transport between male and female mice. Freeze-fracture electron microscopy revealed an increase in the number of tight junction strands of both AQP5+/+ and AQP5−/− male mice after pilocarpine stimulation but no change in strand number in female mice. Average acinar cell volume was increased by ≈1.4-fold in glands from AQP5−/− mice, suggesting an alteration in the volume-sensing machinery of the cell. Western blots revealed that expression of Claudin-7, Claudin-3, and Occludin, critical proteins that regulate the permeability of the tight junction barrier, were significantly decreased in AQP5−/− compared with AQP5+/+ salivary glands. These findings reveal the existence of a gender-influenced molecular mechanism involving AQP5 that allows transcellular and paracellular routes of water transport to act in conjunction.
Intramolecular domain–domain association/dissociation and phosphoryl transfer in the mannitol transporter of
Escherichia coli
are not coupled
Authors: Suh Jeong-Yong , Iwahara Junji , Clore G. Marius
Published: February 2007

The
Escherichia coli
mannitol transporter (II
Mtl
) comprises three domains connected by flexible linkers: a transmembrane domain (C) and two cytoplasmic domains (A and B). II
Mtl
catalyzes three successive phosphoryl-transfer reactions: one intermolecular (from histidine phosphocarrier protein to the A domain) and two intramolecular (from the A to the B domain and from the B domain to the incoming sugar bound to the C domain). A key functional requirement of II
Mtl
is that the A and B cytoplasmic domains be able to rapidly associate and dissociate while maintaining reasonably high occupancy of an active stereospecific AB complex to ensure effective phosphoryl transfer along the pathway. We have investigated the rate of intramolecular domain–domain association and dissociation in IIBA
Mtl
by using
1
H relaxation dispersion spectroscopy in the rotating frame. The open, dissociated state (comprising an ensemble of states) and the closed, associated state (comprising the stereospecific complex) are approximately equally populated. The first-order rate constants for intramolecular association and dissociation are 1.7 (±0.3) × 10
4
and 1.8 (±0.4) × 10
4
s
−1
, respectively. These values compare to rate constants of ≈500 s
−1
for A → B and B → A phosphoryl transfer, derived from qualitative line-shape analysis of
1
H-
15
N correlation spectra taken during the course of active catalysis. Thus, on average, ≈80 association/dissociation events are required to effect a single phosphoryl-transfer reaction. We conclude that intramolecular phosphoryl transfer between the A and B domains of II
Mtl
is rate-limited by chemistry and not by the rate of formation or dissociation of a stereospecific complex in which the active sites are optimally apposed.
Phosphorylation of tau antagonizes apoptosis by stabilizing β-catenin, a mechanism involved in Alzheimer's neurodegeneration
Authors: Li Hong-Lian , Wang Hai-Hong , Liu Shi-Jie , Deng Yan-Qiu , Zhang Yong-Jie , Tian Qing , Wang Xiao-Chuan , Chen Xiao-Qian , Yang Ying , Zhang Jia-Yu , Wang Qun , Xu Huaxi , Liao Francesca-Fang , Wang Jian-Zhi
Published: February 2007

Hyperphosphorylated tau is the major protein subunit of neurofibrillary tangles in Alzheimer's disease (AD) and related tauopathies. It is not understood, however, why the neurofibrillary tangle-containing neurons seen in the AD brains do not die of apoptosis but rather degeneration even though they are constantly awash in a proapoptotic environment. Here, we show that cells overexpressing tau exhibit marked resistance to apoptosis induced by various apoptotic stimuli, which also causes correlated tau hyperphosphorylation and glycogen synthase kinase 3 (GSK-3) activation. GSK-3 overexpression did not potentiate apoptotic stimulus-induced cell apoptosis in the presence of high levels of tau. The resistance of neuronal cells bearing hyperphosphorylated tau to apoptosis was also evident by the inverse staining pattern of PHF-1-positive tau and activated caspase-3 or fragmented nuclei in cells and the brains of rats or tau-transgenic mice. Tau hyperphosphorylation was accompanied by decreases in β-catenin phosphorylation and increases in nuclear translocation of β-catenin. Reduced levels of β-catenin antagonized the antiapoptotic effect of tau, whereas overexpressing β-catenin conferred resistance to apoptosis. These results reveal an antiapoptotic function of tau hyperphosphorylation, which likely inhibits competitively phosphorylation of β-catenin by GSK-3β and hence facilitates the function of β-catenin. Our findings suggest that tau phosphorylation may lead the neurons to escape from an acute apoptotic death, implying the essence of neurodegeneration seen in the AD brains and related tauopathies.
Interfacial plasticity governs strain rate sensitivity and ductility in nanostructured metals
Authors: Zhu Ting , Li Ju , Samanta Amit , Kim Hyoung Gyu , Suresh Subra
Published: February 2007

Nano-twinned copper exhibits an unusual combination of ultrahigh strength and high ductility, along with increased strain-rate sensitivity. We develop a mechanistic framework for predicting the rate sensitivity and elucidating the origin of ductility in terms of the interactions of dislocations with interfaces. Using atomistic reaction pathway calculations, we show that slip transfer reactions mediated by twin boundary are the rate-controlling mechanisms of plastic flow. We attribute the relatively high ductility of nano-twinned copper to the hardening of twin boundaries as they gradually lose coherency during plastic deformation. These findings provide insights into the possible means of optimizing strength and ductility through interfacial engineering.
Large-scale fluid/fluid phase separation of proteins and lipids in giant plasma membrane vesicles
Authors: Baumgart Tobias , Hammond Adam T. , Sengupta Prabuddha , Hess Samuel T. , Holowka David A. , Baird Barbara A. , Webb Watt W.
Published: February 2007

The membrane raft hypothesis postulates the existence of lipid bilayer membrane heterogeneities, or domains, supposed to be important for cellular function, including lateral sorting, signaling, and trafficking. Characterization of membrane lipid heterogeneities in live cells has been challenging in part because inhomogeneity has not usually been definable by optical microscopy. Model membrane systems, including giant unilamellar vesicles, allow optical fluorescence discrimination of coexisting lipid phase types, but thus far have focused on coexisting optically resolvable fluid phases in simple lipid mixtures. Here we demonstrate that giant plasma membrane vesicles (GPMVs) or blebs formed from the plasma membranes of cultured mammalian cells can also segregate into micrometer-scale fluid phase domains. Phase segregation temperatures are widely spread, with the vast majority of GPMVs found to form optically resolvable domains only at temperatures below ≈25°C. At 37°C, these GPMV membranes are almost exclusively optically homogenous. At room temperature, we find diagnostic lipid phase fluorophore partitioning preferences in GPMVs analogous to the partitioning behavior now established in model membrane systems with liquid-ordered and liquid-disordered fluid phase coexistence. We image these GPMVs for direct visual characterization of protein partitioning between coexisting liquid-ordered-like and liquid-disordered-like membrane phases in the absence of detergent perturbation. For example, we find that the transmembrane IgE receptor FcεRI preferentially segregates into liquid-disordered-like phases, and we report the partitioning of additional well known membrane associated proteins. Thus, GPMVs now provide an effective approach to characterize biological membrane heterogeneities.
Genetic evidence for a second domestication of barley (
Hordeum vulgare
) east of the Fertile Crescent
Authors: Morrell Peter L. , Clegg Michael T.
Published: February 2007

Cereal agriculture originated with the domestication of barley and early forms of wheat in the Fertile Crescent. There has long been speculation that barley was domesticated more than once. We use differences in haplotype frequency among geographic regions at multiple loci to infer at least two domestications of barley; one within the Fertile Crescent and a second 1,500–3,000 km farther east. The Fertile Crescent domestication contributed the majority of diversity in European and American cultivars, whereas the second domestication contributed most of the diversity in barley from Central Asia to the Far East.
Extending the absorbing boundary method to fit dwell-time distributions of molecular motors with complex kinetic pathways
Authors: Liao Jung-Chi , Spudich James A. , Parker David , Delp Scott L.
Published: February 2007

Dwell-time distributions, waiting-time distributions, and distributions of pause durations are widely reported for molecular motors based on single-molecule biophysical experiments. These distributions provide important information concerning the functional mechanisms of enzymes and their underlying kinetic and mechanical processes. We have extended the absorbing boundary method to simulate dwell-time distributions of complex kinetic schemes, which include cyclic, branching, and reverse transitions typically observed in molecular motors. This extended absorbing boundary method allows global fitting of dwell-time distributions for enzymes subject to different experimental conditions. We applied the extended absorbing boundary method to experimental dwell-time distributions of single-headed myosin V, and were able to use a single kinetic scheme to fit dwell-time distributions observed under different ligand concentrations and different directions of optical trap forces. The ability to use a single kinetic scheme to fit dwell-time distributions arising from a variety of experimental conditions is important for identifying a mechanochemical model of a molecular motor. This efficient method can be used to study dwell-time distributions for a broad class of molecular motors, including kinesin, RNA polymerase, helicase, F
1
ATPase, and to examine conformational dynamics of other enzymes such as ion channels.
Programmed cell death 1 ligand 1 and tumor-infiltrating CD8+T lymphocytes are prognostic factors of human ovarian cancer
Authors: Hamanishi Junzo , Mandai Masaki , Iwasaki Masashi , Okazaki Taku , Tanaka Yoshimasa , Yamaguchi Ken , Higuchi Toshihiro , Yagi Haruhiko , Takakura Kenji , Minato Nagahiro , Honjo Tasuku , Fujii Shingo
Published: February 2007

The ligands for programmed cell death 1 (PD-1), an immunoinhibitory receptor belonging to CD28/cytotoxic T lymphocyte antigen 4 family, are PD-1 ligand 1 and 2 (PD-Ls). Recent reports suggest that the aberrant expression of PD-Ls on tumor cells impairs antitumor immunity, resulting in the immune evasion of the tumor cells. Although an inverse correlation between the expression level of PD-Ls and patients' prognosis has been reported for several malignant tumors, the follow-up period was limited because of the lack of the antibody (Ab) applicable to paraffin-embedded specimens. Here we generated a new Ab against PD-1 ligand 1 (PD-L1) and analyzed the expression level of PD-Ls in human ovarian cancer using paraffin-embedded specimens. Patients with higher expression of PD-L1 had a significantly poorer prognosis than patients with lower expression. Although patients with higher expression of PD-1 ligand 2 also had a poorer prognosis, the difference was not statistically significant. A significant inverse correlation was observed between PD-L1 expression and the intraepithelial CD8+T lymphocyte count, suggesting that PD-L1 on tumor cells directly suppresses antitumor CD8+T cells. Multivariate analysis showed the expression of PD-L1 on tumor cells and intraepithelial CD8+T lymphocyte count are independent prognostic factors. The PD-1/PD-L pathway can be a good target for restoring antitumor immunity in ovarian cancer.
Retrospective and prospective responses arising in a modeled hippocampus during maze navigation by a brain-based device
Authors: Fleischer Jason G. , Gally Joseph A. , Edelman Gerald M. , Krichmar Jeffrey L.
Published: February 2007

Recent recordings of place field activity in rodent hippocampus have revealed correlates of current, recent past, and imminent future events in spatial memory tasks. To analyze these properties, we used a brain-based device, Darwin XI, that incorporated a detailed model of medial temporal structures shaped by experience-dependent synaptic activity. Darwin XI was tested on a plus maze in which it approached a goal arm from different start arms. In the task, a journey corresponded to the route from a particular starting point to a particular goal. During maze navigation, the device developed place-dependent responses in its simulated hippocampus. Journey-dependent place fields, whose activity differed in different journeys through the same maze arm, were found in the recordings of simulated
CA1
neuronal units. We also found an approximately equal number of journey-independent place fields. The journey-dependent responses were either retrospective, where activity was present in the goal arm, or prospective, where activity was present in the start arm. Detailed analysis of network dynamics of the neural simulation during behavior revealed that many different neural pathways could stimulate any single
CA1
unit. That analysis also revealed that place activity was driven more by hippocampal and entorhinal cortical influences than by sensory cortical input. Moreover, journey-dependent activity was driven more strongly by hippocampal influence than journey-independent activity.
Starch grain evidence for the preceramic dispersals of maize and root crops into tropical dry and humid forests of Panama
Authors: Dickau Ruth , Ranere Anthony J. , Cooke Richard G.
Published: February 2007

The Central American isthmus was a major dispersal route for plant taxa originally brought under cultivation in the domestication centers of southern Mexico and northern South America. Recently developed methodologies in the archaeological and biological sciences are providing increasing amounts of data regarding the timing and nature of these dispersals and the associated transition to food production in various regions. One of these methodologies, starch grain analysis, recovers identifiable microfossils of economic plants directly off the stone tools used to process them. We report on new starch grain evidence from Panama demonstrating the early spread of three important New World cultigens: maize (
Zea mays
), manioc (
Manihot esculenta
), and arrowroot (
Maranta arundinacea
). Maize starch recovered from stone tools at a site located in the Pacific lowlands of central Panama confirms previous archaeobotanical evidence for the use of maize there by 7800–7000 cal BP. Starch evidence from preceramic sites in the less seasonal, humid premontane forests of Chiriquí province, western Panama, shows that maize and root crops were present by 7400–5600 cal BP, several millennia earlier than previously documented. Several local starchy resources, including
Zamia
and
Dioscorea
spp., were also used. The data from both regions suggest that crop dispersals took place via diffusion or exchange of plant germplasm rather than movement of human populations practicing agriculture.
Immunotherapeutic activity of a conjugate of a Toll-like receptor 7 ligand
Authors: Wu Christina C. N. , Hayashi Tomoko , Takabayashi Kenji , Sabet Mojgan , Smee Donald F. , Guiney Donald D. , Cottam Howard B. , Carson Dennis A.
Published: February 2007

The immunotherapeutic activity of Toll-like receptor (TLR) activators has been difficult to exploit because of side effects related to the release and systemic dispersion of proinflammatory cytokines. To overcome this barrier, we have synthesized a versatile TLR7 agonist, 4-[6-amino-8-hydroxy-2-(2-methoxyethoxy)purin-9-ylmethyl]benzaldehyde (UC-1V150), bearing a free aldehyde that could be coupled to many different auxiliary chemical entities through a linker molecule with a hydrazine or amino group without any loss of activity. UC-1V150 was covalently coupled to mouse serum albumin (MSA) at a 5:1 molar ratio to yield a stable molecule with a characteristically altered UV spectrum. Compared with the unconjugated TLR7 agonist, the UC-1V150/MSA was a 10- to 100-fold more potent inducer of cytokine production
in vitro
by mouse bone marrow-derived macrophage and human peripheral blood mononuclear cells. When administrated to the lung, the conjugate induced a prolonged local release of cytokines at levels 10-fold or more higher than those found in serum. Under the same conditions, the untethered TLR7 ligand induced quick systemic cytokine release with resultant toxicity. In addition, two pulmonary infectious disease models were investigated wherein mice were pretreated with the conjugate and then challenged with either
Bacillus anthracis
spores or H1N1 influenza A virus. Significant delay in mortality was observed in both disease models with UC-1V150/MSA-pretreated mice, indicating the potential usefulness of the conjugate as a localized and targeted immunotherapeutic agent.
A haplotype of the human CXCR1 gene protective against rapid disease progression in HIV-1+patients
Authors: Vasilescu A. , Terashima Y. , Enomoto M. , Heath S. , Poonpiriya V. , Gatanaga H. , Do H. , Diop G. , Hirtzig T. , Auewarakul P. , Lauhakirti D. , Sura T. , Charneau P. , Marullo S. , Therwath A. , Oka S. , Kanegasaki S. , Lathrop M. , Matsushima K. , Zagury J.-F. , Matsuda F.
Published: February 2007

Chemokines and their receptors are key factors in the onset and progression of AIDS. Among them, accumulating evidence strongly indicates the involvement of IL-8 and its receptors, CXCR1 and CXCR2, in AIDS-related conditions. Through extensive investigation of genetic variations of the humanCXCR1–CXCR2locus, we identified a haplotype of the CXCR1 gene (CXCR1-Ha) carrying two nonsynonymous single nucleotide polymorphisms,CXCR1_300(Met to Arg) in the N terminus extracellular domain andCXCR1_142(Arg to Cys) in the C terminus intracellular domain. Transfection experiments withCXCR1cDNAs corresponding to theCXCR1-Haand the alternativeCXCR1-HAhaplotype showed reduced expression of CD4 and CXCR4 inCXCR1-Hacells in human osteosarcoma cells as well as in Jurkat and CEM human T lymphocytes. Furthermore, the efficiency of X4-tropic HIV-1NL4–3infection was significantly lower inCXCR1-Hacells than inCXCR1-HAcells. The results were further confirmed by a series of experiments using six HIV-1 clinical isolates from AIDS patients. A genetic association study was performed by using an HIV-1+patient cohort consisting of two subpopulations of AIDS with extreme phenotypes of rapid and slow progression of the disease. The frequency of theCXCR1-Haallele is markedly less frequent in patients with rapid disease onset than those with slow progression (P= 0.0003). These results provide strong evidence of a protective role of theCXCR1-Haallele on disease progression in AIDS, probably acting through modulation of CD4 and CXCR4 expression.
The pRb/E2F cell-cycle pathway mediates cell death in Parkinson's disease
Authors: Höglinger Günter U. , Breunig Joshua J. , Depboylu Candan , Rouaux Caroline , Michel Patrick P. , Alvarez-Fischer Daniel , Boutillier Anne-Laurence , DeGregori James , Oertel Wolfgang H. , Rakic Pasko , Hirsch Etienne C. , Hunot Stéphane
Published: February 2007

The mechanisms leading to degeneration of dopaminergic neurons (DNs) in the substantia nigra of patients with Parkinson's disease (PD) are not completely understood. Here, we show, in the postmortem human tissue, that these neurons aberrantly express mitosis-associated proteins, including the E2F-1 transcription factor, and appear to duplicate their nuclear DNA. We further demonstrate that the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injected into mice and application of its active metabolite 1-methyl-4-phenylpyridinium to mesencephalic cultures activate the retinoblastoma–E2F pathway in postmitotic DNs. We also find that cell death rather than mitotic division followed the toxin-induced replication of DNA, as determined by BrdU incorporation in DNs. In addition, blocking E2F-1 transcription protected cultured DNs against 1-methyl-4-phenylpyridinium toxicity. Finally, E2F-1-deficient mice were significantly more resistant to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic cell death than their wild-type littermates. Altogether, BrdU incorporation in mature neurons and lack of evidence for newborn neurons argue against neuronal turnover in normal conditions or during pathological states in the substantia nigra. Instead, our results demonstrate that mitosis-like signals are activated in mature DNs in patients with PD and mediate neuronal death in experimental models of the disease. Inhibition of mitosis-like signals may therefore provide strategies for neuroprotection in PD.
c-Src protein kinase inhibitors block assembly and maturation of dengue virus
Authors: Chu J. J. H. , Yang Priscilla L.
Published: February 2007

Dengue virus is a mosquito-borne flavivirus that represents an important emerging infectious disease and is an international health concern. Currently, there is no vaccine or effective antiviral therapy to prevent or to treat dengue virus infection. The slow progress in developing antiviral agents might be alleviated by the availability of efficient high-throughput anti-dengue virus screening assays. In this study, we report an immunofluorescence image-based assay suitable for identification of small molecule inhibitors of dengue virus infection and replication. Using this assay, we have discovered that inhibitors of the c-Src protein kinase exhibit a potent inhibitory effect on dengue virus (serotypes 1–4) and murine flavivirus Modoc. Mechanism of action studies demonstrated that the c-Src protein kinase inhibitor dasatinib prevents the assembly of dengue virions within the virus-induced membranous replication complex. These results demonstrate that this cell-based screen may provide a powerful means to identify new potential targets for anti-dengue drug development while simultaneously providing pharmacological probes to investigate dengue virus–host cell interactions at the biochemical level. Given the simplicity and excellent reproducibility of the assay, it should be useful in high-throughput screens of both small molecule and RNAi libraries when implemented on a robotic image-based high-throughput screen (HTS) platform. Given the reasonable clinical safety of inhibitors such as dasatinib and AZD0530, inhibitors of c-Src protein kinase may have the potential to become a new class of anti-dengue viral therapeutic agents.
Regulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor trafficking through PKA phosphorylation of the Glu receptor 1 subunit
Authors: Man Heng-Ye , Sekine-Aizawa Yoko , Huganir Richard L.
Published: February 2007

α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors mediate the majority of excitatory synaptic transmission in the brain. Recent studies have shown that activation of PKA regulates the membrane trafficking of the AMPA receptor Glu receptor 1 (GluR1) subunit, but the role of direct phosphorylation of GluR1 in regulating receptor redistribution is not clear. Here we show that phosphorylation of the GluR1 subunit on serine 845 by PKA is required for PKA-induced increases in AMPA receptor cell-surface expression because it promotes receptor insertion and decreases receptor endocytosis. Furthermore, dephosphorylation of GluR1 serine 845 triggers NMDA-induced AMPA receptor internalization. These findings strongly suggest that dynamic changes in direct phosphorylation of GluR1 by PKA are crucial in the modulation of AMPA receptor trafficking and synaptic plasticity.
HIV-tat induces formation of an LRP–PSD-95– NMDAR–nNOS complex that promotes apoptosis in neurons and astrocytes
Authors: Eugenin Eliseo A. , King Jessie E. , Nath Avindra , Calderon Tina M. , Zukin R. Suzanne , Bennett Michael V. L. , Berman Joan W.
Published: February 2007

HIV infection of the central nervous system can result in neurologic dysfunction with devastating consequences in AIDS patients. NeuroAIDS is characterized by neuronal injury and loss, yet there is no evidence that HIV can infect neurons. Here we show that the HIV-encoded protein tat triggers formation of a macromolecular complex involving the low-density lipoprotein receptor-related protein (LRP), postsynaptic density protein-95 (PSD-95),
N
-methyl-
d
-aspartic acid (NMDA) receptors, and neuronal nitric oxide synthase (nNOS) at the neuronal plasma membrane, and that this complex leads to apoptosis in neurons negative as well as positive for NMDA receptors and also in astrocytes. Blockade of LRP-mediated tat uptake, NMDA receptor activation, or neuronal nitric oxide synthase significantly reduces ensuing neuronal apoptosis, suggesting that formation of this complex is an early step in tat toxicity. We also show that the inflammatory chemokine, CCL2, protects against tat toxicity and inhibits formation of the complex. These findings implicate the complex in HIV-induced neuronal apoptosis and suggest therapeutic targets for intervention in the pathogenesis of NeuroAIDS.
Strategy for reversing resistance to a single anticancer agent in human prostate and pancreatic carcinomas
Authors: Lebedeva Irina V. , Washington Ilyas , Sarkar Devanand , Clark Jennifer A. , Fine Robert L. , Dent Paul , Curiel David T. , Turro Nicholas J. , Fisher Paul B.
Published: February 2007

Effective therapies for most solid cancers, especially those that have progressed to metastasis, remain elusive because of inherent and acquired resistance of tumor cells to conventional treatments. Additionally, the effective therapeutic window for many protocols can be very narrow, frequently resulting in toxicity. The present study explores an anticancer strategy that effectively eliminates resistant cancer cells without exerting deleterious effects on normal cells. This approach employs melanoma differentiation-induced gene-7/interleukin-24 (
mda
-7/IL-24), a cancer-specific, apoptosis-inducing cytokine, in combination with nontoxic doses of a chemical compound from the endoperoxide class that decomposes in water generating singlet oxygen. This combinatorial regimen specifically induced
in vitro
apoptosis in prostate carcinoma cells, with innate resistance to chemotherapy or engineered resistance to
mda
-7/IL-24, as well as pancreatic carcinoma cells inherently resistant to any treatment modality, including
mda
-7/IL-24. Apoptosis induction correlated with increased cellular reactive oxygen species production and was prevented by general antioxidants, such as
N
-acetyl-
l
-cysteine or Tiron. Induction of apoptosis in combination-treated cancer cells correlated with a reduction in the antiapoptotic protein BCL-x
L
. In contrast, both normal prostate and pancreatic epithelial cells were unaffected by the single or combination treatment. These provocative findings suggest that this combinatorial strategy might provide a platform for developing effective treatments for therapy-resistant cancers.
Concerted ATP-induced allosteric transitions in GroEL facilitate release of protein substrate domains in an all-or-none manner
Authors: Kipnis Yakov , Papo Niv , Haran Gilad , Horovitz Amnon
Published: February 2007

The double-ring chaperonin GroEL mediates protein folding, in conjunction with its helper protein GroES, by undergoing ATP-induced conformational changes that are concerted within each heptameric ring. Here we have examined whether the concerted nature of these transitions is responsible for protein substrate release in an all-or-none manner. Two chimeric substrates were designed, each with two different reporter activities that were recovered after denaturation in GroES-dependent and independent fashions, respectively. The refolding of the chimeras was monitored in the presence of GroEL variants that undergo ATP-induced intraring conformational changes that are either sequential (F44W/D155A) or concerted (F44W). Our results show that release of a protein substrate from GroEL in a domain-by-domain fashion is favored when the intraring allosteric transitions of GroEL are sequential and not concerted.
The N-Terminus ofDictyosteliumScar Interacts with Abi and HSPC300 and Is Essential for Proper Regulation and Function
Authors: Caracino Diana , Jones Cheryl , Compton Mark , Saxe Charles L.
Published: February 2007

Scar/WAVE proteins, members of the conserved Wiskott-Aldrich syndrome (WAS) family, promote actin polymerization by activating the Arp2/3 complex. A number of proteins, including a complex containing Nap1, PIR121, Abi1/2, and HSPC300, interact with Scar/WAVE, though the role of this complex in regulating Scar function remains unclear. Here we identify a short N-terminal region of Dictyostelium Scar that is necessary and sufficient for interaction with HSPC300 and Abi in vitro. Cells expressing Scar lacking this N-terminal region show abnormalities in F-actin distribution, cell morphology, movement, and cytokinesis. This is true even in the presence of wild-type Scar. The data suggest that the first 96 amino acids of Scar are necessary for participation in a large-molecular-weight protein complex, and that this Scar-containing complex is responsible for the proper localization and regulation of Scar. The presence of mis-regulated or unregulated Scar has significant deleterious effects on cells and may explain the need to keep Scar activity tightly controlled in vivo either by assembly in a complex or by rapid degradation.
Caveolin 2 Regulates Endocytosis and Trafficking of the M1 Muscarinic Receptor in MDCK Epithelial Cells
Authors: Shmuel Miriam , Nodel-Berner Efrat , Hyman Tehila , Rouvinski Alexander , Altschuler Yoram
Published: February 2007

Clathrin and caveolins are known for their involvement in the internalization of numerous receptors. Here we show that in polarized epithelial Madin-Darby canine kidney cells, both the clathrin machinery and caveolins are involved in the endocytosis and delivery to the plasma membrane (PM) of the M1 muscarinic acetylcholine receptor (mAChR). We initially localized this receptor to the lateral membrane, where it accumulates proximal to the tight junctions. From there it is internalized through the clathrin-mediated pathway. In addition, the receptor may associate on the PM with caveolin (cav) 2 or in intracellular compartments with either cav 2, or monomeric or oligomeric cav 1. Association of the PM M1 mAChR with cav 2 inhibits receptor endocytosis through the clathrin-mediated pathway or retains the receptor in an intracellular compartment. This intracellular association attenuates receptor trafficking. Expression of cav 1 with cav 2 rescues the latter's inhibitory effect. The caveolins stimulate M1 mAChR oligomerization thus maintaining a constant amount of monomeric receptor. These results provide evidence that caveolins play a role in the attenuation of the M1 muscarinic receptor's intracellular trafficking to and from the PM.
The Myosin IXb Motor Activity Targets the Myosin IXb RhoGAP Domain as Cargo to Sites of Actin Polymerization
Authors: van den Boom Frank , Düssmann Heiko , Uhlenbrock Katharina , Abouhamed Marouan , Bähler Martin
Published: February 2007

Myosin IXb (Myo9b) is a single-headed processive myosin that exhibits Rho GTPase-activating protein (RhoGAP) activity in its tail region. Using live cell imaging, we determined that Myo9b is recruited to extending lamellipodia, ruffles, and filopodia, the regions of active actin polymerization. A functional motor domain was both necessary and sufficient for targeting Myo9b to these regions. The head domains of class IX myosins comprise a large insertion in loop2. Deletion of the large Myo9b head loop 2 insertion abrogated the enrichment in extending lamellipodia and ruffles, but enhanced significantly the enrichment at the tips of filopodia and retraction fibers. The enrichment in the tips of filopodia and retraction fibers depended on four lysine residues C-terminal to the loop 2 insertion and the tail region. Fluorescence recovery after photobleaching and photoactivation experiments in lamellipodia revealed that the dynamics of Myo9b was comparable to that of actin. The exchange rates depended on the Myo9b motor region and motor activity, and they were also dependent on the turnover of F-actin. These results demonstrate that Myo9b functions as a motorized RhoGAP molecule in regions of actin polymerization and identify Myo9b head sequences important for in vivo motor properties.
The Short Arm of Laminin γ2 Chain of Laminin-5 (Laminin-332) Binds Syndecan-1 and Regulates Cellular Adhesion and Migration by Suppressing Phosphorylation of Integrin β4 Chain
Authors: Ogawa Takashi , Tsubota Yoshiaki , Hashimoto Junko , Kariya Yoshinobu , Miyazaki Kaoru
Published: February 2007

The proteolytic processing of laminin-5 at the short arm of the γ2 chain (γ2sa) is known to convert this laminin from a cell adhesion type to a motility type. Here, we studied this mechanism by analyzing the functions of γ2sa. In some immortalized or tumorigenic human cell lines, a recombinant γ2sa, in either soluble or insoluble (coated) form, promoted the adhesion of these cells to the processed laminin-5 (Pr-LN5), and it suppressed their migration stimulated by serum or epidermal growth factor (EGF). γ2sa also suppressed EGF-induced tyrosine phosphorylation of integrin β4 and resultant disruption of hemidesmosome-like structures in keratinocytes. γ2sa bound to syndecan-1, and this binding, as well as its cell adhesion activity, was blocked by heparin. By analyzing the activities of three different γ2sa fragments, the active site of γ2sa was localized to the NH2-terminal EGF-like sequence (domain V or LEa). Suppression of syndecan-1 expression by the RNA interference effectively blocked the activities of domain V capable of promoting cell adhesion and inhibiting the integrin β4 phosphorylation. These results demonstrate that domain V of the γ2 chain negatively regulates the integrin β4 phosphorylation, probably through a syndecan-1–mediated signaling, leading to enhanced cell adhesion and suppressed cell motility.
Fatty Acid Remodeling of GPI-anchored Proteins Is Required for Their Raft Association
Authors: Maeda Yusuke , Tashima Yuko , Houjou Toshiaki , Fujita Morihisa , Yoko-o Takehiko , Jigami Yoshifumi , Taguchi Ryo , Kinoshita Taroh
Published: February 2007

Whereas most of the cellular phosphatidylinositol (PI) contain unsaturated fatty chains and are excluded from rafts, GPI-anchored proteins (APs) unusually contain two saturated fatty chains in their PI moiety, and they are typically found within lipid rafts. However, the origin of the saturated chains and whether they are essential for raft association are unclear. Here, we report that GPI-APs, with two saturated fatty chains, are generated from those bearing an unsaturated chain by fatty acid remodeling that occurs most likely in the Golgi and requires post-GPI-attachment to proteins (PGAP)2 and PGAP3. The surface GPI-APs isolated from the PGAP2 and -3 double-mutant Chinese hamster ovary (CHO) cells had unsaturated chains, such as oleic, arachidonic, and docosatetraenoic acids in the sn-2 position, whereas those from wild-type CHO cells had exclusively stearic acid, a saturated chain, indicating that the sn-2 chain is exchanged to a saturated chain. We then assessed the association of GPI-APs with lipid rafts. Recovery of unremodeled GPI-APs from the double-mutant cells in the detergent-resistant membrane fraction was very low, indicating that GPI-APs become competent to be incorporated into lipid rafts by PGAP3- and PGAP2-mediated fatty acid remodeling. We also show that the remodeling requires the preceding PGAP1-mediated deacylation from inositol of GPI-APs in the endoplasmic reticulum.