bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine-tuning anti-tumor immunotherapies via stochastic simulations
Authors: Caravagna Giulio , Barbuti Roberto , d'Onofrio Alberto
Published: March 2012

Background

Anti-tumor therapies aim at reducing to zero the number of tumor cells in a host within their end or, at least, aim at leaving the patient with a sufficiently small number of tumor cells so that the residual tumor can be eradicated by the immune system. Besides severe side-effects, a key problem of such therapies is finding a suitable scheduling of their administration to the patients. In this paper we study the effect of varying therapy-related parameters on the final outcome of the interplay between a tumor and the immune system.

Results

This work generalizes our previous study on hybrid models of such an interplay where interleukins are modeled as a continuous variable, and the tumor and the immune system as a discrete-state continuous-time stochastic process. The hybrid model we use is obtained by modifying the corresponding deterministic model, originally proposed by Kirschner and Panetta. We consider Adoptive Cellular Immunotherapies and Interleukin-based therapies, as well as their combination. By asymptotic and transitory analyses of the corresponding deterministic model we find conditions guaranteeing tumor eradication, and we tune the parameters of the hybrid model accordingly. We then perform stochastic simulations of the hybrid model under various therapeutic settings: constant, piece-wise constant or impulsive infusion and daily or weekly delivery schedules.

Conclusions

Results suggest that, in some cases, the delivery schedule may deeply impact on the therapy-induced tumor eradication time. Indeed, our model suggests that Interleukin-based therapies may not be effective for every patient, and that the piece-wise constant is the most effective delivery to stimulate the immune-response. For Adoptive Cellular Immunotherapies a metronomic delivery seems more effective, as it happens for other anti-angiogenesis therapies and chemotherapies, and the impulsive delivery seems more effective than the piece-wise constant. The expected synergistic effects have been observed when the therapies are combined.
Identification of bovine leukemia virus tax function associated with host cell transcription, signaling, stress response and immune response pathway by microarray-based gene expression analysis
Authors: Arainga Mariluz , Takeda Eri , Aida Yoko
Published: March 2012

Background

Bovine leukemia virus (BLV) is associated with enzootic bovine leukosis and is closely related to human T-cell leukemia virus type I. The Tax protein of BLV is a transcriptional activator of viral replication and a key contributor to oncogenic potential. We previously identified interesting mutant forms of Tax with elevated (TaxD247G) or reduced (TaxS240P) transactivation effects on BLV replication and propagation. However, the effects of these mutations on functions other than transcriptional activation are unknown. In this study, to identify genes that play a role in the cascade of signal events regulated by wild-type and mutant Tax proteins, we used a large-scale host cell gene-profiling approach.

Results

Using a microarray containing approximately 18,400 human mRNA transcripts, we found several alterations after the expression of Tax proteins in genes involved in many cellular functions such as transcription, signal transduction, cell growth, apoptosis, stress response, and immune response, indicating that Tax protein has multiple biological effects on various cellular environments. We also found that TaxD247G strongly regulated more genes involved in transcription, signal transduction, and cell growth functions, contrary to TaxS240P, which regulated fewer genes. In addition, the expression of genes related to stress response significantly increased in the presence of TaxS240P as compared to wild-type Tax and TaxD247G. By contrast, the largest group of downregulated genes was related to immune response, and the majority of these genes belonged to the interferon family. However, no significant difference in the expression level of downregulated genes was observed among the Tax proteins. Finally, the expression of important cellular factors obtained from the human microarray results were validated at the RNA and protein levels by real-time quantitative reverse transcription-polymerase chain reaction and western blotting, respectively, after transfecting Tax proteins into bovine cells and human HeLa cells.

Conclusion

A comparative analysis of wild-type and mutant Tax proteins indicates that Tax protein exerts a significant impact on cellular functions as diverse as transcription, signal transduction, cell growth, stress response and immune response. Importantly, our study is the first report that shows the extent to which BLV Tax regulates the innate immune response.
Characterization of a pneumococcal meningitis mouse model
Authors: Mook-Kanamori Barry , Geldhoff Madelijn , Troost Dirk , van der Poll Tom , van de Beek Diederik
Published: March 2012

Background

S. pneumoniaeis the most common causative agent of meningitis, and is associated with high morbidity and mortality. We aimed to develop an integrated and representative pneumococcal meningitis mouse model resembling the human situation.

Methods

Adult mice (C57BL/6) were inoculated in the cisterna magna with increasing doses ofS. pneumoniaeserotype 3 colony forming units (CFU; n = 24, 104, 105, 106and 107CFU) and survival studies were performed. Cerebrospinal fluid (CSF), brain, blood, spleen, and lungs were collected. Subsequently, mice were inoculated with 104CFUS. pneumoniaeserotype 3 and sacrificed at 6 (n = 6) and 30 hours (n = 6). Outcome parameters were bacterial outgrowth, clinical score, and cytokine and chemokine levels (using Luminex®) in CSF, blood and brain. Meningeal inflammation, neutrophil infiltration, parenchymal and subarachnoidal hemorrhages, microglial activation and hippocampal apoptosis were assessed in histopathological studies.

Results

Lower doses of bacteria delayed onset of illness and time of death (median survival CFU 104, 56 hrs; 105, 38 hrs, 106, 28 hrs. 107, 24 hrs). Bacterial titers in brain and CSF were similar in all mice at the end-stage of disease independent of inoculation dose, though bacterial outgrowth in the systemic compartment was less at lower inoculation doses. At 30 hours after inoculation with 104CFU ofS. pneumoniae, blood levels of KC, IL6, MIP-2 and IFN- γ were elevated, as were brain homogenate levels of KC, MIP-2, IL-6, IL-1β and RANTES. Brain histology uniformly showed meningeal inflammation at 6 hours, and, neutrophil infiltration, microglial activation, and hippocampal apoptosis at 30 hours. Parenchymal and subarachnoidal and cortical hemorrhages were seen in 5 of 6 and 3 of 6 mice at 6 and 30 hours, respectively.

Conclusion

We have developed and validated a murine model of pneumococcal meningitis.
In-home solid fuel use and cardiovascular disease: a cross-sectional analysis of the Shanghai Putuo study
Authors: Lee Mi-Sun , Hang Jing-qing , Zhang Feng-ying , Dai He-lian , Su Li , Christiani David C
Published: March 2012

Background

Although recent research evidence suggests an association between household air pollution from solid fuel use, such as coal or biomass, and cardiovascular events such as hypertension, little epidemiologic data are available concerning such exposure effects on cardiovascular endpoints other than hypertension. We explored the association between in-home solid fuel use and self-reported diagnoses of cardiovascular endpoints, such as hypertension, coronary heart disease (CHD), stroke, and diabetes.

Methods

We analyzed 14,068 Chinese adults, aged 18 years and older. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated using logistic regression models for the risk of each outcome after adjusting for potential confounders.

Results

The use of solid fuel in home was significantly associated with an increased risk for hypertension (OR 1.70, 95% CI 1.40 to 2.07), CHD (OR 2.58, 95% CI 1.53 to 4.32), and diabetes (OR 2.48, 95% CI 1.59 to 3.86), after adjusting for potential confounders. Compared with individuals in the lowest tertile of the duration of solid fuel exposure, those in the highest tertile of the duration of solid fuel exposure had an increased odds of hypertension (OR 1.73, 95% CI 1.45 to 2.06), stroke (OR 1.87, 95% CI 1.03 to 3.38), and diabetes (OR 3.18, 95% CI 2.11 to 4.78).

Conclusions

Our data suggest that in-home solid fuel exposure maybe associated with increased risk for hypertension, CHD, stroke, and diabetes in the Chinese adult population. Further large-scale longitudinal studies are warranted to confirm these findings.
MicroRNA-378a-5p promotes trophoblast cell survival, migration and invasion by targeting Nodal
Authors: Luo Linlin , Ye Gang , Nadeem Lubna , Fu Guodong , Yang Burton B. , Dunk Caroline , Lye Stephen , Peng Chun
Published: March 2012

Nodal is a member of the transforming growth factor-β superfamily that plays critical roles during embryogenesis. Recently, we have reported that Nodal inhibits trophoblast cell proliferation, migration and invasion, but induces apoptosis in human placenta. In this study, we examined the regulation of Nodal by microRNAs. In silico analysis of Nodal 3′UTR revealed a potential binding site for miR-378a-5p. In luciferase reporter assays, we found that miR-378a-5p suppressed the luciferase activity of a reporter plasmid containing Nodal 3′UTR but this suppressive effect was completely abolished when the predicted target site was mutated. Western blot analysis showed that miR-378a-5p decreased while anti-miR-378a-5p increased Nodal protein levels. These results indicate that miR-378a-5p targets Nodal 3′UTR to repress its expression. Stable transfection of miR-378a-5p precursor, mir-378a, into HTR8/SVneo cells enhanced cell survival, proliferation, migration and invasion. Transient transfection of mature miR-378a-5p mimics, and to a lesser extent, siRNA targeting Nodal, produced similar effects. On the other hand, anti-miR-378a-5p inhibited cell migration and invasion. In addition, overexpression of Nodal reversed the invasion-promoting effect of miR-378a-5p. Furthermore, miR-378a-5p enhanced, while anti-miR-378a-5p suppressed, the outgrowth and spreading of extravillous trophoblast cells in first trimester placental explants. Finally, miR-378a-5p was detected in human placenta throughout different stages of gestation and in preterm pregnancies, placental miR-378a-5p levels were lower in preeclamptic patients than in healthy controls. Taken together, these findings strongly suggest that miR-378a-5p plays an important role in human placental development by regulating trophoblast cell growth, survival, migration and invasion and that miR-378a-5p exerts these effects, at least in part, via the suppression of Nodal expression.
Human Mob1 proteins are required for cytokinesis by controlling microtubule stability
Authors: Florindo Claudia , Perdigão Joana , Fesquet Didier , Schiebel Elmar , Pines Jonathon , Tavares Álvaro A.
Published: March 2012

The completion of cytokinesis requires abscission of the midbody, a microtubule-rich cytoplasmic bridge that connects the daughter cells before their final separation. Although it has been established that both the midbody structure and membrane fusion are essential for abscission, the biochemical machinery and the cellular processes of abscission remain ill-defined. Here we report that human Mob1A and Mob1B proteins are involved in the regulation of abscission of the intercellular bridge. The Mob family is a group of highly conserved proteins in eukaryotes, described as binding partners as well as co-activators of protein kinases of the Ndr family, and as members of the Hippo pathway. We show that depletion of Mob1A and Mob1B by RNAi causes abscission failure as a consequence of hyper-stabilization of microtubules in the midbody region. Interestingly, depleting Mob1 also increases cell motility after cytokinesis, and induces prolonged centriole separation in G1 phase. In contrast, centrosomes fail to split when either Mob1A or Mob1B is overexpressed. Our findings indicate that human Mob1 proteins are involved in the regulation of microtubule stability at the midbody. We conclude that Mob1A and Mob1B are needed for cell abscission and centriole re-joining after telophase and cytokinesis.
Loss of Pnn expression results in mouse early embryonic lethality and cellular apoptosis through SRSF1-mediated alternative expression of Bcl-xS and ICA**
Authors: Leu Steve , Lin Yen-Ming , Wu Chu-Han , Ouyang Pin
Published: March 2012

Pinin (Pnn), a serine/arginine-rich (SR)-related protein, has been shown to play multiple roles within eukaryotic cells including in cell-cell adhesion, cell migration, regulation of gene transcription, mRNA export, and alternative splicing. In this study, an attempt to generate mice homozygously deficient in Pnn failed due to early embryonic lethality. To evaluate the effects of loss of Pnn expression on cell survival, RNA interference experiments were performed in MCF-7 cells. With Pnn-depletion, cellular apoptosis and nuclear condensation were observed. In addition, nuclear speckles were disrupted, and expression levels of SR proteins were diminished. RT-PCR analysis showed that alternative splicing patterns of SRSF1 as well as of apoptosis-related genes Bcl-x and ICAD were altered and expression levels of Bim isoforms were modulated in Pnn-depleted cells. Cellular apoptosis induced by Pnn depletion was rescued by overexpression of SRSF1 which also restored generation of Bcl-xL and functionless ICAD. Pnn expression is, therefore, essential for survival of mouse embryos and the breast carcinoma cell line MCF-7. Moreover, Pnn-depletion, modulated by SRSF1, determines cellular apoptosis through activation of expression of pro-apoptotic Bcl-xS transcripts.
Role of low-density lipoprotein receptor related protein 1 (LRP1) in CCN2/connective tissue growth factor (CTGF) protein transport in chondrocytes
Authors: Kawata Kazumi , Kubota Satoshi , Eguchi Takanori , Aoyama Eriko , Moritani Norifumi H. , Kondo Seiji , Nishida Takashi , Takigawa Masaharu
Published: March 2012

LRP1 is known to be a receptor for signal transmission and endocytosis. We formerly reported that LRP1 regulates WNT/β-catenin and protein kinase C signaling in chondrocytes and represses the hypertrophy of chondrocytes during endochondral ossification, and that LRP1 is co-localized with a ligand, CCN2, which conducts endochondral ossification, on chondrocytes. However, the role of LRP1 in endocytotic transport of CCN2 in chondrocytes is not yet understood. In the present study, we investigated the interaction between LRP1 and CCN2 during endocytotic trafficking.

RNAi-mediated knockdown of LRP1 in chondrocytic HCS-2/8 cells showed that the amount of exogenous CCN2 binding/incorporation was decreased in the LRP1 down-regulated cells. Importantly, we observed that CCN2 internalization in chondrocytes was dependent on clathrin and internalizated CCN2 was co-localized with an early or recycling endosome marker. Transcytosis of CCN2 through HCS-2/8 cells was confirmed by performing experiments with a trans-well apparatus, and the amount of transcytosed CCN2 was decreased by an LRP1 antagonist. These findings rule out possible leakage and confirm the critical involvement of LRP1 during experimental transcytosis. Moreover, under the hypoxic condition mimicking the cartilaginous microenvironment, the production level of LRP1 and the amount of transcytosed CCN2 were increased, which increases were neutralized by the LRP1 antagonist. The distribution of LRP1 and its antagonist in the growth plate in vivo was consistent with that of CCN2 therein, which was produced by and transported from the chondrocytes in the prehypertrophic layer.

These findings suggest that LRP1 mediates the transcytosis of CCN2, which may be a critical event that determines the distribution of CCN2 in cartilage.
Functional analysis of parvin and different modes of IPP-complex assembly at integrin sites during Drosophila development
Authors: Vakaloglou Katerina M. , Chountala Maria , Zervas Christos G.
Published: March 2012

Integrin-linked kinase (ILK), PINCH and Parvin constitute the tripartite IPP-complex that maintains the integrin-actin link at embryonic muscle attachment sites (MASs) in Drosophila. Here we showed that parvin null mutations in Drosophila exhibit defects in muscle adhesion, similar to ILK and PINCH mutants. Furthermore, the identical muscle phenotype of the triple mutant, which for the first time in any organism removed the entire IPP-complex function, genetically demonstrated that parvin, ILK and PINCH function synergistically. This is consistent with the tight localization of the tripartite complex at sites of integrin adhesion, namely MASs in the developing embryo and focal contact-like structures in the wing epithelium. Parvin contains tandem unconventional Calponin-Homology (CH) domains separated by a linker sequence, and a less well conserved N-terminal region. In vivo structure-function analysis revealed that all the domains are essential for parvin function, whereas recruitment at integrin adhesion sites is mediated by two localization signals: one located within the CH2-domain as previously reported, and a second novel signal within the CH1 domain. Interestingly, this site is masked by the linker region between the two CH-domains, suggesting a regulatory mechanism to control parvin localization. Finally, whereas in muscles only ILK controls the stability and localization of both PINCH and parvin, in the wing epithelium the three proteins mutually depend on each other. Thus molecular differences exist in the assembly properties of IPP-complex in specific tissues during development, where differential modulation of the integrin connection to cytoskeleton is required.
Botulinum neurotoxin D-C uses synaptotagmin I/II as receptors and human synaptotagmin II is not an effective receptor for type B, D-C, and G toxins
Authors: Peng Lisheng , Berntsson Ronnie P-A , Tepp William H. , Pitkin Rose M. , Johnson Eric A. , Stenmark Pål , Dong Min
Published: March 2012

Botulinum neurotoxins are classified into seven types (BoNT/A-G), but multiple subtype and mosaic toxins exist. These subtype/mosaic toxins share high sequence identity and presumably the same receptors/substrates with their parental toxins. Here we report that a mosaic toxin, BoNT/D-C, uses different receptors from its parental toxin BoNT/C. BoNT/D-C, but not BoNT/C, binds directly to the luminal domains of synaptic vesicle proteins synaptotagmin (Syt) I and II, and requires expression of Syt I/II to enter neurons. The Syt II luminal fragment containing the toxin binding site can block BoNT/D-C entry into neurons and reduce its toxicity in vivo in mice. We also found that gangliosides increase binding of BoNT/D-C to Syt I/II and enhance the ability of the Syt II luminal fragment to block BoNT/D-C entry into neurons. These data establish Syt I/II, in conjunction with gangliosides, as the receptors for BoNT/D-C, and indicate that BoNT/D-C is functionally distinct from BoNT/C. We further found that BoNT/D-C recognizes the same binding site on Syt I/II where BoNT/B and G also bind, but utilizes a receptor binding interface distinct from BoNT/B and G. Finally, we also report that human and chimpanzee Syt II cannot bind and function as the receptor for BoNT/B, D-C, and G due to a single residue change from rodent Syt II within the toxin binding site, potentially reducing the potency of these BoNTs in humans and chimpanzees.
The Ndc80 internal loop is required for recruitment of the Ska complex to establish end-on microtubule attachment to kinetochores.
Authors: Zhang Gang , Kelstrup Christian D. , Hu Xiao-Wen , Hansen Mathilde J Kaas , Singleton Martin R. , Olsen Jesper V. , Nilsson Jakob
Published: March 2012

The Ndc80 complex establishes end-on attachment of kinetochores to microtubules essential for chromosome segregation. The Ndc80 subunit is characterized by an N-terminal region, that binds directly to microtubules, and a long coiled-coil region that interacts with Nuf2. A loop region in Ndc80 that generates a kink in the structure disrupts the long coiled-coil region but the exact function of this loop is not clear.

Here we show that this loop region is essential for end-on attachment of kinetochores to microtubules in human cells. Cells expressing loop mutants of Ndc80 are unable to align the chromosomes and stable kinetochore fibers are absent. Through quantitative mass spectrometry and immunofluorescence we find that the binding of the Ska complex depends on the loop region explaining why end-on attachment is defective. This underscores the importance of the Ndc80 loop region in coordinating chromosome segregation through the recruitment of specific proteins to the kinetochore.
Cdc14-dependent dephosphorylation of Inn1 contributes to Inn1-Cyk3 complex formation
Authors: Palani Saravanan , Meitinger Franz , Boehm Martin E. , Lehmann Wolf D. , Pereira Gislene
Published: March 2012

In Saccharomyces cerevisiae, the Cdc14 phosphatase plays a well-established role in reverting phosphorylation events on substrates of the mitotic cyclin-dependent kinase (M-Cdk1), thereby promoting mitotic exit and down-regulation of M-Cdk1 activity. Cdc14 localizes at the site of cell cleavage after M-Cdk1 inactivation, suggesting that Cdc14 may perform a critical, yet ill-defined, role during cytokinesis. Here, we identified Inn1, as a novel direct substrate of both M-Cdk1 and Cdc14. Cdc14 co-localizes with Inn1 at the cell division site and interacts with the C-terminal proline rich domain of Inn1 that mediates its binding to the SH3-domain containing proteins Hof1 and Cyk3. We show that phosphorylation of Inn1 by Cdk1 partially perturbs the interaction of Inn1 with Cyk3 thereby reducing the levels of Cyk3 at the cell division site. We propose that Cdc14 counteracts Cdk1 phosphorylation of Inn1 to facilitate Inn1-Cyk3 complex formation and so promote cytokinesis.
The Occurrence of π Molecular Orbitals in Planar Boron Clusters
Authors: Nakagami Yuto , Suzuki Nobu-Yuki , Sekine Rika , Matsuura Taisuke , Aihara Jun-ichi
Published: March 2012

The energy of the lowest π molecular orbital in a planar boron cluster can be estimated from the connectivity of constituent boron atoms, or the mean valency of the boron atoms. Low-energy π molecular orbitals were then predicted to occur in all realistic planar polycyclic boron clusters. In fact, all such boron clusters studied have one or more π molecular orbitals with two or more π electrons. They are aromatic with positive topological resonance energies. π Conjugation and aromaticity must be totally or partially responsible for the planarity of low-energy boron clusters.
Hydrogen Production from Ethanol Steam Reforming over Noble Metal Catalysts Supported on SiO2: Mechanism of Methane Production and Reaction Conditions for Suppression of Methane Production
Authors: Ando Yuji , Matsuoka Koichi , Takagi Hideyuki , Kuramoto Koji
Published: March 2012

We investigated ethanol steam reforming over Rh/SiO2, Pt/SiO2, Pd/SiO2, and Ru/SiO2 at 573–723 K using a fluidized-bed quartz reactor to determine which reaction conditions suppressed CH4 production and increased H2 and CO2 production. At temperatures under 623 K over Rh/SiO2 and Ru/SiO2, CH4 was produced not only by ethanol decomposition but also by the reduction of CO2 and CO to CH4. At 723 K, the product yields over all four catalysts were strongly influenced by the partial pressure of ethanol: CH4 production was suppressed, and H2 and CO2 production was increased, at low partial pressure of ethanol. These experimental results can be explained in terms of the partial pressures of CO2 and H2.
Temperature-Independent Stereoselectivity in Intramolecular Cycloaddition of Ketene Generated from Diazoester in Solution and in Vapor Phase: How Entropy Term Governs the Selectivity
Authors: Sugimura Takashi , Mitani Eigo , Tei Takahiro , Okuyama Tadashi , Kamiya Katsumasa , Matsui Toru , Shigeta Yasuteru
Published: March 2012

The intramolecular [2 + 2] cycloaddition between alkene and ketene linked with 2,4-pentanediol tether was performed in a wide range of temperature, −60 to +400 °C. When the ketene was generated by photolysis at the diazoester in a pentane solution, the cycloadduct obtained was of 90–98% de depending on the structure of the olefinic part as well as the structure of the tether. Notably, each substrate showed practically constant selectivity in a temperature range of −60 to +130 °C. The thermolysis in vapor phase above 250 °C also gave the same cycloadducts; the de values of the kinetic products are similar to those obtained by photolysis. The observed temperature-independent stereoselectivity should be controlled by the entropy term, which is also investigated by ab initio calculations in the framework of density functional theory.
A Review Essay on The Enlightened Economy: An Economic History of Britain 1700–1850 by Joel Mokyr
Authors: Clark Gregory
Published: March 2012

The British Industrial Revolution is the key break in world history. Yet the timing, location, and cause of this Revolution are unsolved puzzles. Joel Mokyr's book is one of a number of recent attempted solutions. He explains the Industrial Revolution through the arrival of a particular ideology in Britain, associated with the earlier European intellectual movement of the Enlightenment. This review considers how Mokyr's “idealist” approach fares as an account of the Industrial Revolution, compared to the spate of recent proposed “materialist” explanations. (JEL N13, N63)
Economic History or History of Economics? A Review Essay on Sylvia Nasar's Grand Pursuit: The Story of Economic Genius
Authors: Ashenfelter Orley
Published: March 2012

In this essay, I review Sylvia Nasar's long awaited new history of economics, Grand Pursuit: The Story of Economic Genius. I describe how the book is an economic history of the period 1850–1950, with distinguished economists' stories inserted in appropriate places. Nasar's goal is to show how economists work, but also to show that they are people too—with more than enough warts and foibles to show they are human! I contrast the general view of the role of economics in Grand Pursuit with Robert Heilbroner's remarkably different conception in The Worldly Philosophers: The Lives, Times, and Ideas of the Great Economic Thinkers. I also discuss more generally the question of why economists might be interested in their history at all. (JEL B10, B20, B30, N00)
Fat intake leads to differential response of rat adipocytes to glucose, insulin and ascorbic acid
Authors: Garcia-Diaz Diego F , Campion Javier , Arellano Arianna V , Milagro Fermin I , Moreno-Aliaga Maria J , Martinez J Alfredo
Published: March 2012

Antioxidant-based treatments have emerged as novel and interesting approaches to counteract fat accumulation in obesity and associated metabolic disturbances. Adipocytes from rats that were fed on chow or high-fat diet (HFD) for 50 d were isolated (primary adipocytes) and incubated (72 h) on low (LG; 5.6 mmol/L) or high (HG; 25 mmol/L) glucose levels, in the presence or absence of 1.6 nmol/L insulin and 200 μmol/L vitamin C (VC). Adipocytes from HFD-fed animals presented lower insulin-induced glucose uptake, lower lactate and glycerol release, and lower insulin-induced secretion of some adipokines as compared with controls. HG treatment restored the blunted response to insulin regarding apelin secretion in adipocytes from HFD-fed rats. VC treatment inhibited the levels of nearly all variables, irrespective of the adipocytes’ dietary origin. The HG treatment reduced adipocyte viability, and VC protected from this toxic effect, although more drastically in control adipocytes. Summing up, in vivo chow or HFD intake determines a differential response to insulin and glucose treatments that appears to be dependent on the insulin-resistance status of the adipocytes, while VC modifies some responses from adipocytes independently of the previous dietary intake of the animals.
Pathways for venous thromboembolic prophylaxis in medical and surgical patients
Authors: Darvall K , Bradbury A
Published: March 2012

Despite the fact that venous thromboembolism (VTE) is one of the most widely studied areas in medicine, and despite the availability of data from numerous RCTs, there are many areas where the evidence is insufficient to allow grade A recommendations to be made. In these areas published guidelines often differ in their advice. In this chapter we primarily discuss the National Institute of Clinical and Health Excellence (NICE) VTE prophylaxis pathways in the context of other guidance published by the Scottish Intercollegiate Guideline Network and the American Colleges of Physicians and Chest Physicians. Evidence for the use of both mechanical and pharmacological thromboprophylaxis is discussed for both medical and surgical patients.
Venous thromboembolism in the paediatric patient
Authors: Kelleher D , Shalhoub J , Davies A H
Published: March 2012

Venous thromboembolism is a concern in the paediatric population and its incidence seems to be increasing. Symptoms and signs may be subtle so a high degree of suspicion is needed. Paediatric patients represent a unique challenge in the provision of anticoagulation due to their unique physiology.
Problems with Tests of the Missingness Mechanism in Quantitative Policy
Studies
Authors: Rhoads Christopher H.
Published: March 2012

Policy analysts involved in quantitative research have many options for
handling missing data. The method chosen will often greatly influence the
substantive policy conclusions that will be drawn from the data. The most
frequent methods for handling missing data assume that the data are missing
at random (MAR). The current paper notes that an omnibus, nonparametric test
of the MAR assumption is impossible using the observed data alone.
Nonetheless various purported tests of the missingness mechanism (including
tests of MAR) appear in the literature. The current paper clarifies that all
of these tests rely on some assumption that cannot be tested from the data.
The paper notes that tests of the missingness mechanism are frequently
misinterpreted and it clarifies the appropriate interpretation of such
tests. Policy analysts are encouraged not to develop the false impression
that modern procedures for handling missing data in conjunction with tests
of the missingness mechanism provide protection against the ill effects of
missing data. Any justification for a particular approach to handling
missing data must be come from substantive knowledge of the missingness
process, not from the data.
Optimized analytic reconstruction for SPECT
Authors: Guillement Jean-Pol , Novikov Roman G.
Published: March 2012

We develop optimized analytic reconstruction for the single-photon emission
computed tomography (SPECT). This reconstruction is based on (1) Novikov's
exact and Chang's approximate inversion formulas for the attenuated ray
transform, (2) filtering techniques, and (3) Morozov type discrepancy
principle. Our numerical examples include comparisons with the standard least
square and expectation maximization iterative SPECT reconstructions.
Differential Roles of the Dorsolateral and Midlateral Striatum in Punished Cocaine Seeking
Authors: Jonkman Sietse , Pelloux Yann , Everitt Barry J.
Published: March 2012

Continued instrumental drug seeking despite contingent punishment is a core phenotype of drug addiction. Although the neuroanatomical basis of punished drug seeking is unclear, we hypothesize that the sensorimotor striatum, a structure that mediates habitual drug seeking, also mediates punished cocaine seeking. Forelimb sensorimotor projections into the striatum of the rat extend from the dorsolateral to midlateral striatum. Here, we selectively inactivated the dorsolateral and midlateral striatum in rats responding for cocaine in a seeking–taking task. We inactivated both regions after the acquisition of cocaine seeking, after extended cocaine self-administration and finally after the introduction of intermittent, seeking-contingent foot shock. The results show that inactivation of the dorsolateral striatum selectively disrupted punished drug seeking but did not affect unpunished drug seeking, even after extended training. Inactivation of the midlateral striatum, on the other hand, disrupted drug seeking at all stages of training. The effect of inactivating the dorsolateral striatum under punishment conditions was present before delivery of the first shock in the session, and responding reverted to baseline the next day. Thus, inactivation of the dorsolateral striatum seems to enhance the influence of recalled threat of negative consequences of cocaine seeking. The proportional reduction in responding after inactivation of the dorsolateral striatum did not vary with the individual level of compulsivity. Together, these results suggest a novel differentiation of function in the sensorimotor striatum, where the dorsolateral striatum selectively mediates the rigidity of responding after overtraining, while the midlateral striatum mediates responding itself at all stages of training.
Excitotoxicity Downregulates TrkB.FL Signaling and Upregulates the Neuroprotective Truncated TrkB Receptors in Cultured Hippocampal and Striatal Neurons
Authors: Gomes João R. , Costa João T. , Melo Carlos V. , Felizzi Federico , Monteiro Patrícia , Pinto Maria J. , Inácio Ana R. , Wieloch Tadeusz , Almeida Ramiro D. , Grãos Mário , Duarte Carlos B.
Published: March 2012

Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival through activation of TrkB receptors. ThetrkBgene encodes a full-length receptor tyrosine kinase (TrkB.FL) and its truncated (T1/T2) isoforms. We investigated the changes in TrkB protein levels and signaling activity under excitotoxic conditions, which are characteristic of brain ischemia, traumatic brain injury, and neurodegenerative disorders. Excitotoxic stimulation of cultured rat hippocampal or striatal neurons downregulated TrkB.FL and upregulated a truncated form of the receptor (TrkB.T). Downregulation of TrkB.FL was mediated by calpains, whereas the increase in TrkB.T protein levels required transcription and translation activities. Downregulation of TrkB.FL receptors in hippocampal neurons correlated with a decrease in BDNF-induced activation of the Ras/ERK and PLCγ pathways. However, calpain inhibition, which prevents TrkB.FL degradation, did not preclude the decrease in signaling activity of these receptors. On the other hand, incubation with anisomycin, to prevent the upregulation of TrkB.T, protected to a large extent the TrkB.FL signaling activity, suggesting that truncated receptors may act as dominant-negatives. The upregulation of TrkB.T under excitotoxic conditions was correlated with an increase in BDNF-induced inhibition of RhoA, a mediator of excitotoxic neuronal death. BDNF fully protected hippocampal neurons transduced with TrkB.T when present during excitotoxic stimulation with glutamate, in contrast with the partial protection observed in cells overexpressing TrkB.FL or expressing GFP. These results indicate that BDNF protects hippocampal neurons by two distinct mechanisms: through the neurotrophic effects of TrkB.FL receptors and by activation of TrkB.T receptors coupled to inhibition of the excitotoxic signaling.
Epigenetic Modulation of Homer1a Transcription Regulation in Amygdala and Hippocampus with Pavlovian Fear Conditioning
Authors: Mahan Amy L. , Mou Liping , Shah Nirali , Hu Jia-Hua , Worley Paul F. , Ressler Kerry J.
Published: March 2012

The consolidation of conditioned fear involves upregulation of genes necessary for long-term memory formation. An important question remains as to whether this results in part from epigenetic regulation and chromatin modulation. We examined whether Homer1a, which is required for memory formation, is necessary for Pavlovian cued fear conditioning, whether it is downstream of BDNF-TrkB activation, and whether this pathway utilizes histone modifications for activity-dependent transcriptional regulation. We initially found that Homer1a knock-out mice exhibited deficits in cued fear conditioning (5 tone–shock presentations with 70 dB, 6 kHz tones and 0.5 s, 0.6 mA footshocks). We then demonstrated that: (1) Homer1a mRNA increases after fear conditioningin vivowithin both amygdala and hippocampus of wild-type mice; (2) it increases after BDNF application to primary hippocampal and amygdala culturesin vitro; and (3) these increases are dependent on transcription and MAPK signaling. Furthermore, using chromatin immunoprecipitation we found that bothin vitroandin vivomanipulations result in decreases in Homer1 promoter H3K9 methylation in amygdala cells but increases in Homer1 promoter H3 acetylation in hippocampal cells. However, no changes were observed in H4 acetylation or H3K27 dimethylation. Inhibition of histone deacetylation by sodium butyrate enhanced contextual but not cued fear conditioning and enhanced Homer1 H3 acetylation in the hippocampus. These data provide evidence for dynamic epigenetic regulation of Homer1a following BDNF-induced plasticity and during a BDNF-dependent learning process. Furthermore, upregulation of this gene may be regulated through distinct epigenetic modifications in the hippocampus and amygdala.
Cholinergic Induction of Input-Specific Late-Phase LTP via Localized Ca2+Release in the Visual Cortex
Authors: Cho Kwang-Hyun , Jang Hyun-Jong , Jo Yang-Hyeok , Singer Wolf , Rhie Duck-Joo
Published: March 2012

Acetylcholine facilitates long-term potentiation (LTP) and long-term depression (LTD), substrates of learning, memory, and sensory processing, in which acetylcholine also plays a crucial role. Ca2+ions serve as a canonical regulator of LTP/LTD but little is known about the effect of acetylcholine on intracellular Ca2+dynamics. Here, we investigated dendritic Ca2+dynamics evoked by synaptic stimulation and the resulting LTP/LTD in layer 2/3 pyramidal neurons of the rat visual cortex. Under muscarinic stimulation, single-shock electrical stimulation (SES) inducing ∼20 mV EPSP, applied via a glass electrode located ∼10 μm from the basal dendrite, evoked NMDA receptor-dependent fast Ca2+transients and the subsequent Ca2+release from the inositol 1,4,5-trisphosphate (IP3)-sensitive stores. These secondary dendritic Ca2+transients were highly localized within 10 μm from the center (SD = 5.0 μm). The dendritic release of Ca2+was a prerequisite for input-specific muscarinic LTP (LTPm). Without the secondary Ca2+release, only muscarinic LTD (LTDm) was induced. D(−)-2-amino-5-phosphopentanoic acid and intracellular heparin blocked LTPm as well as dendritic Ca2+release. A single burst consisting of 3 EPSPs with weak stimulus intensities instead of the SES also induced secondary Ca2+release and LTPm. LTPm and LTDm were protein synthesis-dependent. Furthermore, LTPm was confined to specific dendritic compartments and not inducible in distal apical dendrites. Thus, cholinergic activation facilitated selectively compartment-specific induction of late-phase LTP through IP3-dependent Ca2+release.
Photoreceptor Coupling Mediated by Connexin36 in the Primate Retina
Authors: O'Brien Jennifer J. , Chen Xiaoming , MacLeish Peter R. , O'Brien John , Massey Stephen C.
Published: March 2012

Photoreceptors are coupled via gap junctions in many mammalian species. Cone-to-cone coupling is thought to improve sensitivity and signal-to-noise ratio, while rod-to-cone coupling provides an alternative rod pathway active under twilight or mesopic conditions (Smith et al., 1986; DeVries et al., 2002; Hornstein et al., 2005). Gap junctions are composed of connexins, and connexin36 (Cx36), the dominant neuronal connexin, is expressed in the outer plexiform layer. Primate (Macaca mulatta) cone pedicles, labeled with an antibody against cone arrestin (7G6) were connected by a network of fine processes called telodendria and, in double-labeled material, Cx36 plaques were located precisely at telodendrial contacts between cones, suggesting strongly they are Cx36 gap junctions. Each red/green cone made nonselective connections with neighboring red/green cones. In contrast, blue cone pedicles were smaller with relatively few short telodendria and they made only rare or equivocal Cx36 contacts with adjacent cones. There were also many smaller Cx36 plaques around the periphery of every cone pedicle and along a series of very fine telodendria that were too short to reach adjacent members of the cone pedicle mosaic. These small Cx36 plaques were closely aligned with nearly every rod spherule and may identify sites of rod-to-cone coupling, even though the identity of the rod connexin has not been established. We conclude that the matrix of cone telodendria is the substrate for photoreceptor coupling. Red/green cones were coupled indiscriminately but blue cones were rarely connected with other cones. All cone types, including blue cones, made gap junctions with surrounding rod spherules.
Eye Movements Modulate the Spatiotemporal Dynamics of Word Processing
Authors: Temereanca Simona , Hämäläinen Matti S. , Kuperberg Gina R. , Stufflebeam Steve M. , Halgren Eric , Brown Emery N.
Published: March 2012

Active reading requires coordination between frequent eye movements (saccades) and short fixations in text. Yet, the impact of saccades on word processing remains unknown, as neuroimaging studies typically employ constant eye fixation. Here we investigate eye-movement effects on word recognition processes in healthy human subjects using anatomically constrained magnetoencephalography, psychophysical measurements, and saccade detection in real time. Word recognition was slower and brain responses were reduced to words presented early versus late after saccades, suggesting an overall transient impairment of word processing after eye movements. Response reductions occurred early in visual cortices and later in language regions, where they colocalized with repetition priming effects. Qualitatively similar effects occurred when words appeared early versus late after background movement that mimicked saccades, suggesting that retinal motion contributes to postsaccadic inhibition. Further, differences in postsaccadic and background-movement effects suggest that central mechanisms also contribute to postsaccadic modulation. Together, these results suggest a complex interplay between visual and central saccadic mechanisms during reading.
GluRδ2 Assembles Four Neurexins intoTrans-Synaptic Triad to Trigger Synapse Formation
Authors: Lee Sung-Jin , Uemura Takeshi , Yoshida Tomoyuki , Mishina Masayoshi
Published: March 2012

Elucidation of molecular mechanisms of synapse formation is a prerequisite for the understanding of neural wiring, higher brain functions, and mental disorders. Thetrans-synaptic interaction of postsynaptic glutamate receptor δ2 (GluRδ2) and presynaptic neurexins (NRXNs) through cerebellin precursor protein 1 (Cbln1) mediates synapse formationin vivoin the cerebellum. Here, we asked how thetrans-synaptic triad induces synapse formation. Native GluRδ2 existed as a tetramer in the membrane, whereas the N-terminal domain (NTD) of GluRδ2 formed a stable homodimer. When incubated with cultured mouse cerebellar granule cells (GCs), dimeric GluRδ2-NTD and Cbln1 exerted little effect on the accumulation of punctate immunostaining signals for Bassoon and vesicular glutamate transporter 1 in GC axons. However, tetramerized GluRδ2-NTD stimulated the accumulation of these presynaptic proteins in the axons. Analysis of Cbln1 mutants suggested that the binding sites of GluRδ2 and NRXN1β on Cbln1 are differential. Furthermore, there was no competition in the binding to Cbln1 between GluRδ2-NTD and the extracellular domain (ECD) of NRXN1β. Thus, GluRδ2 and Cbln1 interacted with each other rather independently of Cbln1-NRXN1β interaction and vice versa. Gel filtration and isothermal titration calorimetry analyses consistently showed that dimeric GluRδ2-NTD and hexameric Cbln1 assembled in the 1:1 ratio, whereas hexameric Cbln1 and the laminin–neurexin–sex hormone-binding globulin domain of NRXN1β-ECD assembled in the 1:2 ratio. Thus, the synaptogenic triad is assembled from tetrameric GluRδ2, hexameric Cbln1, and monomeric NRXN in the ratio of 1:2:4. These results suggest that GluRδ2 triggers synapse formation by clustering four NRXNs through triad formation.
The Mode of Retinal Presynaptic Inhibition Switches with Light Intensity
Authors: Ichinose Tomomi , Lukasiewicz Peter D.
Published: March 2012

Excitatory amino acid transporters (EAATs) terminate signaling in the CNS by clearing released glutamate. Glutamate also evokes an EAAT-mediated Cl−current, but its role in CNS signaling is poorly understood. We show in mouse retina that EAAT-mediated Cl−currents that were evoked by light inhibit rod pathway signaling. EAATs reside on rod bipolar cell axon terminals where GABA and glycine receptors also mediate light-evoked inhibition. We found that the mode of inhibition depended on light intensity. Dim light evoked GABAergic and glycinergic inhibition with rapid kinetics and a large spatial extent. Bright light evoked predominantly EAAT-mediated inhibition with slow kinetics and a small spatial extent. The switch to EAAT-mediated signaling in bright light supplements receptor-mediated signaling to expand the dynamic range of inhibition and contributes to the transition from rod to cone signaling by suppressing rod pathway signaling in bright light conditions.
A Role for Perirhinal Cortex in Memory for Novel Object–Context Associations
Authors: Watson Hilary C. , Wilding Edward L. , Graham Kim S.
Published: March 2012

It is debated whether functional divisions between structures in the medial temporal lobe (MTL), in particular the perirhinal cortex (PrC) and hippocampus (HC), are best conceptualized according to memory process (Diana et al., 2007; Ranganath, 2010; Wixted et al., 2010) or stimulus category (Graham et al., 2010). In the former account, PrC is critical for item familiarity but not recollection of associations between items and their contexts (which is instead dependent upon the HC; Ranganath et al., 2004). In the latter theory, complex object representations in PrC are capable of supporting memory for objects as well as for object–context associations, particularly when there is a demand to discriminate between highly visually similar objects (Cowell et al., 2010). To adjudicate between these accounts, human participants were scanned while making two different judgments about visually presented objects (is the object common or uncommon, or does the object have more edges or curves). In a subsequent, unscanned, retrieval phase, participants made item (old/new) followed by context (encoding task) judgments about previously seen and novel objects. Neural activity at encoding was separated according to the accuracy of the retrieval judgments. PrC activity predicted successful item–context judgments, a result that remained when item-memory strength was equated across objects for which the context was remembered or forgotten. These data imply that the function of PrC goes beyond processing item-based memory information, contributing additionally to memory for item–context associations when the stimuli are objects (Graham et al., 2010).