bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating independence
Authors: Barak B. , Kindler G. , Shaltiel R. , Sudakov B. , Wigderson A.
Published: May 2010

We present new explicit constructions of
deterministic
randomness extractors, dispersers and related objects. We say that a distribution
X
on binary strings of length
n
is a δ-source if
X
assigns probability at most 2

−δ
n

to any string of length
n
. For every δ>0, we construct the following poly(
n
)-time computable functions:

2-source disperser:
D:({0, 1}

n

)
2
→ {0, 1} such that for any two independent δ-sources
X
1
,
X
2
we have that the support of
D
(
X
1
,
X
2
) is {0, 1}.

Bipartite Ramsey graph:
Let
N
=2

n

. A corollary is that the function
D
is a 2-coloring of the edges of
K

N,N

(the complete bipartite graph over two sets of
N
vertices) such that any induced subgraph of size
N
δ
by
N
δ
is not monochromatic.

3-source extractor:
E
:({0, 1}
n
)
3
→ {0, 1} such that for any three independent δ-sources
X
1
,
X
2
,
X
3
we have that
E
(
X
1
,
X
2
,
X
3
) is
o
(1)-close to being an unbiased random bit.

No previous explicit construction was known for either of these for any δ<1/2, and these results constitute significant progress to long-standing open problems.

A component in these results is a new construction of condensers that may be of independent interest: This is a function
C
:{0, 1}
n
→ ({0, 1}
n/c
)
d
(where
c
and
d
are constants that depend only on δ) such that for every δ-source
X
one of the output blocks of
C(X)
is (exponentially close to) a 0.9-source. (This result was obtained independently by Ran Raz.)

The constructions are quite involved and use as building blocks other new and known objects. A recurring theme in these constructions is that objects that were designed to work with independent inputs, sometimes perform well enough with correlated, high entropy inputs.

The construction of the disperser is based on a new technique which we call “the challenge-response mechanism” that (in some sense) allows “identifying high entropy regions” in a given pair of sources using only one sample from the two sources.
Optimal matching between spatial datasets under capacity constraints
Authors: U Leong Hou , Mouratidis Kyriakos , Yiu Man Lung , Mamoulis Nikos
Published: May 2010

Consider a set of
customers
(e.g., WiFi receivers) and a set of
service providers
(e.g., wireless access points), where each provider has a
capacity
and the quality of service offered to its customers is anti-proportional to their distance. The
Capacity Constrained Assignment
(CCA) is a matching between the two sets such that (i) each customer is assigned to at most one provider, (ii) every provider serves no more customers than its capacity, (iii) the maximum possible number of customers are served, and (iv) the sum of Euclidean distances within the assigned provider-customer pairs is minimized. Although max-flow algorithms are applicable to this problem, they require the complete distance-based bipartite graph between the customer and provider sets. For large spatial datasets, this graph is expensive to compute and it may be too large to fit in main memory. Motivated by this fact, we propose efficient algorithms for
optimal assignment
that employ novel edge-pruning strategies, based on the spatial properties of the problem. Additionally, we develop incremental techniques that maintain an optimal assignment (in the presence of updates) with a processing cost several times lower than CCA recomputation from scratch. Finally, we present
approximate
(i.e., suboptimal) CCA solutions that provide a tunable trade-off between result accuracy and computation cost, abiding by theoretical quality guarantees. A thorough experimental evaluation demonstrates the efficiency and practicality of the proposed techniques.
Return specification inference and result clustering for keyword search on XML
Authors: Liu Ziyang , Chen Yi
Published: May 2010

Keyword search enables Web users to easily access XML data without the need to learn a structured query language and to study possibly complex data schemas. Existing work has addressed the problem of selecting qualified data nodes that match keywords and connecting them in a meaningful way, in the spirit of inferring the
where clause
in XQuery. However, how to infer the
return clause
for keyword searches is an open problem.

To address this challenge, we present a keyword search engine for data-centric XML, XSeek, to infer the semantics of the search and identify return nodes effectively. XSeek recognizes possible entities and attributes inherently represented in the data. It also distinguishes between predicates and return specifications in query keywords. Then based on the analysis of both XML data structures and keyword patterns, XSeek generates return nodes. Furthermore, when the query is ambiguous and it is hard or impossible to determine the desirable return information, XSeek clusters the query results according to their semantics based on the user-specified granularity, and enables the user to easily browse and select the desired ones. Extensive experimental studies show the effectiveness and efficiency of XSeek.
Inference of concise regular expressions and DTDs
Authors: Bex Geert Jan , Neven Frank , Schwentick Thomas , Vansummeren Stijn
Published: May 2010

We consider the problem of inferring a concise Document Type Definition (DTD) for a given set of XML-documents, a problem that basically reduces to learningconciseregular expressions from positive examples strings. We identify two classes of concise regular expressions—the single occurrence regular expressions (SOREs) and the chain regular expressions (CHAREs)—that capture the far majority of expressions used in practical DTDs. For the inference of SOREs we present several algorithms that first infer an automaton for a given set of example strings and then translate that automaton to a corresponding SORE, possibly repairing the automaton when no equivalent SORE can be found. In the process, we introduce a novel automaton to regular expression rewrite technique which is of independent interest. When only a very small amount of XML data is available, however (for instance when the data is generated by Web service requests or by answers to queries), these algorithms produce regular expressions that are too specific. Therefore, we introduce a novel learning algorithm crx that directly infers CHAREs (which form a subclass of SOREs) without going through an automaton representation. We show that crx performs very well within its target class on very small datasets.
Encryption policies for regulating access to outsourced data
Authors: Vimercati Sabrina De Capitani Di , Foresti Sara , Jajodia Sushil , Paraboschi Stefano , Samarati Pierangela
Published: May 2010

Current access control models typically assume that resources are under the strict custody of a trusted party which monitors each access request to verify if it is compliant with the specified access control policy. There are many scenarios where this approach is becoming no longer adequate. Many clear trends in Web technology are creating a need for owners of sensitive information to manage access to it by legitimate users using the services of
honest but curious
third parties, that is, parties trusted with providing the required service but not authorized to read the actual data content. In this scenario, the data owner encrypts the data before outsourcing and stores them at the server. Only the data owner and users with knowledge of the key will be able to decrypt the data. Possible access authorizations are to be enforced by the owner. In this article, we address the problem of enforcing selective access on outsourced data without need of involving the owner in the access control process. The solution puts forward a novel approach that combines cryptography with authorizations, thus enforcing access control via
selective encryption
. The article presents a formal model for access control management and illustrates how an authorization policy can be translated into an equivalent encryption policy while minimizing the amount of keys and cryptographic tokens to be managed. The article also introduces a two-layer encryption approach that allows the data owner to outsource, besides the data, the complete management of the authorization policy itself, thus providing efficiency and scalability in dealing with policy updates. We also discuss experimental results showing that our approach is able to efficiently manage complex scenarios.
Querying and repairing inconsistent numerical databases
Authors: Flesca Sergio , Furfaro Filippo , Parisi Francesco
Published: May 2010

The problem of extracting consistent information from relational databases violating integrity constraints on numerical data is addressed. In particular, aggregate constraints defined as linear inequalities on aggregate-sum queries on input data are considered. The notion of repair as consistent set of updates at attribute-value level is exploited, and the characterization of several data-complexity issues related to repairing data and computing consistent query answers is provided. Moreover, a method for computing “reasonable” repairs of inconsistent numerical databases is provided, for a restricted but expressive class of aggregate constraints. Several experiments are presented which assess the effectiveness of the proposed approach in real-life application scenarios.
A power-aware mapping approach to map IP cores onto NoCs under bandwidth and latency constraints
Authors: Wang Xiaohang , Yang Mei , Jiang Yingtao , Liu Peng
Published: May 2010

In this article, we investigate the Intellectual Property (IP) mapping problem that maps a given set of IP cores onto the tiles of a mesh-based Network-on-Chip (NoC) architecture such that the power consumption due to intercore communications is minimized. This IP mapping problem is considered under both bandwidth and latency constraints as imposed by the applications and the on-chip network infrastructure. By examining various applications' communication characteristics extracted from their respective communication trace graphs, two distinguishable connectivity templates are realized: the graphs with tightly coupled vertices and those with distributed vertices. These two templates are formally defined in this article, and different mapping heuristics are subsequently developed to map them. In general, tightly coupled vertices are mapped onto tiles that are physically close to each other while the distributed vertices are mapped following a graph partition scheme. Experimental results on both random and multimedia benchmarks have confirmed that the proposed template-based mapping algorithm achieves an average of 15% power savings as compared with MOCA, a fast greedy-based mapping algorithm. Compared with a branch-and-bound--based mapping algorithm, which produces near optimal results but incurs an extremely high computation cost, the proposed algorithm, due to its polynomial runtime complexity, can generate the results of almost the same quality with much less CPU time. As the on-chip network size increases, the superiority of the proposed algorithm becomes more evident.
An analysis of on-chip interconnection networks for large-scale chip multiprocessors
Authors: Sanchez Daniel , Michelogiannakis George , Kozyrakis Christos
Published: May 2010

With the number of cores of chip multiprocessors (CMPs) rapidly growing as technology scales down, connecting the different components of a CMP in a scalable and efficient way becomes increasingly challenging. In this article, we explore the architectural-level implications of interconnection network design for CMPs with up to 128 fine-grain multithreaded cores. We evaluate and compare different network topologies using accurate simulation of the full chip, including the memory hierarchy and interconnect, and using a diverse set of scientific and engineering workloads.

We find that the interconnect has a large impact on performance, as it is responsible for 60% to 75% of the miss latency. Latency, and not bandwidth, is the primary performance constraint, since, even with many threads per core and workloads with high miss rates, networks with enough bandwidth can be efficiently implemented for the system scales we consider. From the topologies we study, the flattened butterfly consistently outperforms the mesh and fat tree on all workloads, leading to performance advantages of up to 22%. We also show that considering interconnect and memory hierarchy together when designing large-scale CMPs is crucial, and neglecting either of the two can lead to incorrect conclusions. Finally, the effect of the interconnect on overall performance becomes more important as the number of cores increases, making interconnection choices especially critical when scaling up.
Female Gametophyte Development in Flowering Plants
Authors: Yang Wei-Cai , Shi Dong-Qiao , Chen Yan-Hong
Published: May 2010

The multicellular female gametophyte, a unique feature of higher plants, provides us with an excellent experimental system to address fundamental questions in biology. During the past few years, we have gained significant insight into the mechanisms that control embryo sac polarity, gametophytic cell specification, and recognition between male and female gametophytic cells. An auxin gradient has been shown for the first time to function in the female gametophyte to regulate gametic cell fate, and key genes that control gametic cell fate have also been identified. This review provides an overview of these exciting discoveries with a focus on molecular and genetic data.
Improving Photosynthetic Efficiency for Greater Yield
Authors: Zhu Xin-Guang , Long Stephen P. , Ort Donald R.
Published: May 2010

Increasing the yield potential of the major food grain crops has contributed very significantly to a rising food supply over the past 50 years, which has until recently more than kept pace with rising global demand. Whereas improved photosynthetic efficiency has played only a minor role in the remarkable increases in productivity achieved in the last half century, further increases in yield potential will rely in large part on improved photosynthesis. Here we examine inefficiencies in photosynthetic energy transduction in crops from light interception to carbohydrate synthesis, and how classical breeding, systems biology, and synthetic biology are providing new opportunities to develop more productive germplasm. Near-term opportunities include improving the display of leaves in crop canopies to avoid light saturation of individual leaves and further investigation of a photorespiratory bypass that has already improved the productivity of model species. Longer-term opportunities include engineering into plants carboxylases that are better adapted to current and forthcoming CO2concentrations, and the use of modeling to guide molecular optimization of resource investment among the components of the photosynthetic apparatus, to maximize carbon gain without increasing crop inputs. Collectively, these changes have the potential to more than double the yield potential of our major crops.
Chloroplast RNA Metabolism
Authors: Stern David B. , Goldschmidt-Clermont Michel , Hanson Maureen R.
Published: May 2010

The chloroplast genome encodes proteins required for photosynthesis, gene expression, and other essential organellar functions. Derived from a cyanobacterial ancestor, the chloroplast combines prokaryotic and eukaryotic features of gene expression and is regulated by many nucleus-encoded proteins. This review covers four major chloroplast posttranscriptional processes: RNA processing, editing, splicing, and turnover. RNA processing includes the generation of transcript 5′ and 3′ termini, as well as the cleavage of polycistronic transcripts. Editing converts specific C residues to U and often changes the amino acid that is specified by the edited codon. Chloroplasts feature introns of groups I and II, which undergo protein-facilitated cis- or trans-splicing in vivo. Each of these RNA-based processes involves proteins of the pentatricopeptide motif-containing family, which does not occur in prokaryotes. Plant-specific RNA-binding proteins may underpin the adaptation of the chloroplast to the eukaryotic context.
Starch: Its Metabolism, Evolution, and Biotechnological Modification in Plants
Authors: Zeeman Samuel C. , Kossmann Jens , Smith Alison M.
Published: May 2010

Starch is the most widespread and abundant storage carbohydrate in plants. We depend upon starch for our nutrition, exploit its unique properties in industry, and use it as a feedstock for bioethanol production. Here, we review recent advances in research in three key areas. First, we assess progress in identifying the enzymatic machinery required for the synthesis of amylopectin, the glucose polymer responsible for the insoluble nature of starch. Second, we discuss the pathways of starch degradation, focusing on the emerging role of transient glucan phosphorylation in plastids as a mechanism for solubilizing the surface of the starch granule. We contrast this pathway in leaves with the degradation of starch in the endosperm of germinated cereal seeds. Third, we consider the evolution of starch biosynthesis in plants from the ancestral ability to make glycogen. Finally, we discuss how this basic knowledge has been utilized to improve and diversify starch crops.
Diversification of P450 Genes During Land Plant Evolution
Authors: Mizutani Masaharu , Ohta Daisaku
Published: May 2010

Plant cytochromes P450 (P450s) catalyze a wide variety of monooxygenation/hydroxylation reactions in primary and secondary metabolism. The number of P450 genes in plant genomes is estimated to be up to 1% of total gene annotations of each plant species. This implies that diversification within P450 gene superfamilies has led to the emergence of new metabolic pathways throughout land plant evolution. The conserved P450 families contribute to chemical defense mechanisms under terrestrial conditions and several are involved in hormone biosynthesis and catabolism. Species-specific P450 families are essential for the biosynthetic pathways of species-specialized metabolites. Future genome-wide analyses of P450 gene clusters and coexpression networks should help both in identifying the functions of many orphan P450s and in understanding the evolution of this versatile group of enzymes.
Auxin Biosynthesis and Its Role in Plant Development
Authors: Zhao Yunde
Published: May 2010

Indole-3-acetic acid (IAA), the main auxin in higher plants, has profound effects on plant growth and development. Both plants and some plant pathogens can produce IAA to modulate plant growth. Although the genes and biochemical reactions for auxin biosynthesis in some plant pathogens are well understood, elucidation of the mechanisms by which plants produce auxin has proven to be difficult. So far, no single complete pathway of de novo auxin biosynthesis in plants has been firmly established. However, recent studies have led to the discoveries of several genes in tryptophan-dependent auxin biosynthesis pathways. Recent findings have also determined that local auxin biosynthesis plays essential roles in many developmental processes including gametogenesis, embryogenesis, seedling growth, vascular patterning, and flower development. In this review, I summarize the recent advances in dissecting auxin biosynthetic pathways and how the understanding of auxin biosynthesis provides a crucial angle for analyzing the mechanisms of plant development.
Histone Methylation in Higher Plants
Authors: Liu Chunyan , Lu Falong , Cui Xia , Cao Xiaofeng
Published: May 2010

Histone methylation plays a fundamental role in regulating diverse developmental processes and is also involved in silencing repetitive sequences in order to maintain genome stability. The methylation marks are written on lysine or arginine by distinct enzymes, namely, histone lysine methyltransferases (HKMTs) or protein arginine methyltransferases (PRMTs). Once established, the methylation marks are specifically recognized by the proteins that act as readers and are interpreted into specific biological outcomes. Histone methylation status is dynamic; methylation marks can be removed by eraser enzymes, the histone demethylases (HDMs). The proteins responsible for writing, reading, and erasing the methylation marks are known mostly in animals. During the past several years, a growing body of literature has demonstrated the impact of histone methylation on genome management, transcriptional regulation, and development in plants. The aim of this review is to summarize the biochemical, genetic, and molecular action of histone methylation in two plants, the dicot Arabidopsis and the monocot rice.
Acute elevation of plasma lipids does not affect ATP synthesis in human skeletal muscle
Authors: Brehm A. , Krššák M. , Schmid A. I. , Nowotny P. , Waldhäusl W. , Roden M.
Published: May 2010

Prolonged elevation of plasma triglycerides and free fatty acids (FFA) reduces insulin-stimulated glucose disposal and myocellular flux through ATP synthase (fATPase). However, the early effects of lipids per se on fATPase are as yet unclear. Thus, this study examined glucose disposal and fATPase during 3 h of FFA elevation in the presence of low plasma insulinemia. Euglycemic pancreatic clamps with low-dose insulin supplementation (6 mU·m body surface area−2·min−1) were performed in eight healthy men with (LIP) or without (CON) lipid infusion to measure whole body glucose disposal. 31P/1H magnetic resonance spectroscopy of calf muscle was applied to quantify fATPase and concentrations of glucose 6-phosphate (G6P), inorganic phosphate (Pi), phosphocreatine (PCr), ADP, pH, and IMCL before and during the clamps. Lipid infusion increased plasma FFA approximately twofold and decreased glucose disposal by ∼50% (110–180 min: LIP 0.87 ± 0.45 vs. CON 1.75 ± 0.42 mg·kg−1·min−1, P = 0.002; means ± SD). Intramyocellular G6P tended to rise only under control conditions, whereas PCr, ADP, pH, and IMCL remained unchanged from fasting in LIP and CON. Although Pi concentrations increased by ∼18%, fATPase remained unchanged from fasting during the clamps (LIP 10.2 ± 2.2 vs. CON 10.5 ± 2.6 μmol·g muscle−1·min−1, P = not significant). We conclude that 3 h of lipid elevation fail to affect ATP synthesis despite marked reduction of whole body glucose uptake. This suggests that lipid-induced insulin resistance results primarily from mechanisms decreasing glucose uptake rather than from direct interference of fatty acid metabolites with mitochondrial function.
Identification, Characterization, and Effects ofXenopus laevisPNAS-4 Gene on Embryonic Development
Authors: Yan Fei , Ruan Xu-zhi , Yang Han-shuo , Yao Shao-hua , Zhao Xin-yu , Gou Lan-tu , Ma Fan-xin , Yuan Zhu , Deng Hong-xin , Wei Yu-quan
Published: May 2010

Apoptosis plays an important role in embryonic development. PNAS-4 has been demonstrated to induce apoptosis in several cancer cells. In this study, we clonedXenopus laevisPNAS-4 (xPNAS-4), which is homologous to the human PNAS-4 gene. Bioinformatics analysis for PNAS-4 indicated that xPNAS-4 shared 87.6% identity with human PNAS-4 and 85.5% with mouse PNAS-4. The phylogenetic tree of PNAS-4 protein was also summarized. An analysis of cellular localization using an EGFP-fused protein demonstrated that xPNAS-4 was localized in the perinuclear region of the cytoplasm. RT-PCR analysis revealed that xPNAS-4, as a maternally expressed gene, was present in all stages of early embryo development. Whole-mount in situ hybridization showed that xPNAS-4 was mainly expressed in ectoderm and mesoderm. Furthermore, microinjection of xPNAS-4 mRNA in vivo caused developmental defects manifesting as a small eye phenotype in theXenopousembryos, and as a small eye or one-eye phenotype in developing zebrafish embryos. In addition, embryos microinjected with xPNAS-4 antisense morpholino oligonucleotides (MOs) exhibited a failure of head development and shortened axis.
Expression of Monocarboxylate Transporters 1, 2, and 4 in Human Tumours and Their Association with CD147 and CD44
Authors: Pinheiro Céline , Reis Rui M. , Ricardo Sara , Longatto-Filho Adhemar , Schmitt Fernando , Baltazar Fátima
Published: May 2010

Monocarboxylate transporters (MCTs) are important cellular pH regulators in cancer cells; however, the value of MCT expression in cancer is still poorly understood. In the present study, we analysed MCT1, MCT2, and MCT4 protein expression in breast, colon, lung, and ovary neoplasms, as well as CD147 and CD44. MCT expression frequency was high and heterogeneous among the different tumours. Comparing with normal tissues, there was an increase in MCT1 and MCT4 expressions in breast carcinoma and a decrease in MCT4 plasma membrane expression in lung cancer. There were associations between CD147 and MCT1 expressions in ovarian cancer as well as between CD147 and MCT4 in both breast and lung cancers. CD44 was only associated with MCT1 plasma membrane expression in lung cancer. An important number of MCT1 positive cases are negative for both chaperones, suggesting that MCT plasma membrane expression in tumours may depend on a yet nonidentified regulatory protein.
Stafne's Defect with Buccal Cortical Expansion: A Case Report
Authors: Flores Campos Paulo Sérgio , Oliveira José Aloysio Carvalho , Dantas Janaina Araújo , de Melo Daniela Pita , Pena Nilson , Santos Luís Antônio Nogueira , Crusoé-Rebello Iêda Margarida Rocha
Published: May 2010

A rare case of Stafne's bone cavity, type III-G, is reported in a 49-year-old male patient who had been referred to a private clinic for a routine evaluation. The final diagnosis was based on computed tomography. Scintigraphy played a fundamental role in determining the most likely etiology.
Facile Access to Aldol Products from Aromatic and Heteroaromatic Aldehydes Using Ruthenium Catalyst
Authors: Tabatabaeian Khalil , Mamaghani Manouchehr , Mahmoodi Nosrat O. , Keshavarz Elahe
Published: May 2010

A new method for the synthesis of aldol products is described. The reaction of aromatic and heteroaromatic aldehydes with 1-(thiophen-2-yl)ethanone in the presence of ruthenium chloride hydrate combined with ligand provided the related aldol adducts, in a short time at room temperature in good yields (77–84%).
The Role of the Hedgehog Signaling Pathway in the Development of Basal Cell Carcinoma and Opportunities for Treatment
Authors: Caro Ivor , Low Jennifer A.
Published: May 2010

The hedgehog (Hh) signaling pathway plays an important role in embryogenesis across multiple species. Its activity is reduced or absent in adult organisms. However, activation of the pathway has been shown to be a factor in the development of a number of human malignancies and inhibition of the pathway is being investigated as a potential treatment for multiple cancers. The most extensively investigated and best characterized is basal cell carcinoma (BCC), which occurs in both an inherited form (basal cell nevus syndrome or Gorlin's syndrome) and a sporadic form. Sporadic BCCs are the most common human malignancy. There is recent data available on the use of a small molecule inhibitor of the pathway in BCC. Clin Cancer Res; 16(13); 3335–9. ©2010 AACR.
Altered Fate of Subventricular Zone Progenitor Cells and Reduced Neurogenesis following Neonatal Stroke
Authors: Spadafora Ruggero , Gonzalez Fernando F. , Derugin Nikita , Wendland Michael , Ferriero Donna , McQuillen Patrick
Published: May 2010

Objective: To investigate the effects of neonatal stroke on progenitor cells lining the lateral ventricles. Methods: Intraventricular injection of replication-incompetent green fluorescent protein (GFP)-expressing lentivirus was performed in postnatal day 1 (P1) rats to specifically label radial glia/type B neural stem cells and ependymal cells of the lateral ventricle. A subset of animals was exposed to transient middle cerebral artery occlusion (MCAO) at P7, with mild or moderate injury confirmed by diffusion-weighted MRI and histology. Newborn cells were identified by GFP expression, location and expression of cell type-specific markers in the striatum, cortex and olfactory bulb using confocal microscopy and systematic random sampling. Results: Three weeks lentiviral GFP transduction of cells in the lateral ventricle, abundant GFP-expressing neurons and glia were identified in the rostral migratory stream, olfactory bulb and striatum as expected from labeling the subventricular zone (SVZ) type B neural stem cell lineage. Two weeks following mild or severe focal stroke at P7, no GFP-expressing neurons were detected in striatum or cortex although some single-labeled doublecortin+ immature neurons were detected in the penumbra. The densities of GFP+/ glial fibrillary acidic protein (GFAP)+ astrocytes and GFP+/O4+ oligodendrocytes were reduced in the striatum following MCAO (4.8 ± 1.02 vs. 2.5 ± 0.4 cells/high-power field, HPF; p = 0.005; 2.8± 1 vs. 0.5 ± 0.2 cells/HPF, p = 0.008). Furthermore, there was a reduction of GFP+ cells in the olfactory bulb following MCAO (58.8 ± 14.9 vs. 19.6 ± 5.4 cells/HPF, p = 0.025). Finally, there was an increased percentage of GFP+/GFAP+ cells (70 vs. 50%), with a decreased proportion of GFP+/O4+ cells (14 vs. 30%) in injured animals. Conclusion: Neurogenesis originating from cells of the lateral ventricle, including SVZ type B cells, is significantly reduced following neonatal stroke. Furthermore, neonatal stroke disrupts gliogenesis in the striatum, decreasing overall numbers of new glia and shifting the population towards astrocytes.
Effects of Antenatal Betamethasone and Dexamethasone on the Lung Expression of Vascular Endothelial Growth Factor and Alveolarization in Newborn Rats Exposed to Acute Hypoxia and Recovered in Normoxia or Hyperoxia
Authors: Remesal Ana , San Feliciano Laura , Isidoro-García María , Ludeña Dolores
Published: May 2010

The use of antenatal corticosteroids is widespread and it is important to know their effect(s) on vascular endothelial growth factor (VEGF), which plays a crucial role in pulmonary development. The purpose of this study was to compare pulmonary VEGF expression in newborn rats that were exposed to antenatal betamethasone versus dexamethasone under normoxia, hypoxia and oxidative stress, and to evaluate its impact on alveolarization. Betamethasone, dexamethasone or equivalent saline solution (control group) was administered to pregnant rats. Newborn rats were randomized to room air, hypoxia followed by hyperoxia, or hypoxia followed by air. Pulmonary VEGF protein, VEGF mRNA, and alveolarization were evaluated at 4 days of life. Betamethasone and dexamethasone were observed to have different actions on VEGF expression with a correlation with alveolarization. Antenatal dexamethasone decreased VEGF expression, and dexamethasone and hyperoxia had an additive effect on the inhibition of VEGF with a reduction in alveolar development. Betamethasone appeared to have an effect on the induction of the expression of VEGF, and it seemed to inhibit the negative action of hyperoxia on VEGF. Moreover, betamethasone did not produce a decrease in alveolarization. Our results support the notion that betamethasone could be better than dexamethasone for antenatal lung maturation.
Dexamethasone Treatment after the First Week of Life for Bronchopulmonary Dysplasia in Preterm Infants: A Systematic Review
Authors: Doyle Lex W. , Ehrenkranz Richard A. , Halliday Henry L.
Published: May 2010

Background: Dexamethasone has powerful anti-inflammatory effects and has been used to treat established bronchopulmonary dysplasia (BPD), but it is uncertain whether the benefits outweigh the risks of treatment. Objectives: To determine the effect of late (>7 days) postnatal dexamethasone treatment compared with control (placebo or nothing) to prevent or treat BPD in the preterm infant. Methods: Randomised controlled trials (RCTs) of late postnatal dexamethasone therapy to treat or prevent BPD were sought using methods of the Cochrane Collaboration. Data regarding clinical outcomes including mortality, BPD, death or BPD, complications during the primary hospitalisation, and long-term outcome were abstracted and analysed using RevMan 5. Results: 19 RCTs enrolling 1,345 participants were eligible for this review. Late dexamethasone treatment reduced neonatal mortality, but not later mortality. Benefits of late dexamethasone included reductions in failure to extubate, BPD and the combined outcome of death or BPD. There were clear short-term complications, including hyperglycaemia and hypertension, but not intestinal perforation. Trends of an increase in cerebral palsy or abnormal neurological examination were partly offset by a trend in the opposite direction in death before late follow-up. Conclusions: The benefits of late dexamethasone may not outweigh actual or potential adverse effects. Given the evidence of both benefits and harms of treatment, and the limitations of the evidence at present, it appears prudent to reserve the use of late dexamethasone to infants who cannot be weaned from mechanical ventilation, and to minimise the dose and duration of any course of treatment.
Spectral-Domain Optical Coherence Tomography Use in Macular Diseases: A Review
Authors: Wolf Sebastian , Wolf-Schnurrbusch Ute
Published: May 2010

The introduction of spectral-domain optical coherence tomography (SD-OCT) has improved the clinical value for assessment of the eyes with macular disease. This article reviews the advances of SD-OCT for the diagnostic of various macular diseases. These include vitreomacular traction syndrome, cystoid macular edema/diabetic macular edema, epiretinal membranes, full-thickness macular holes, lamellar holes, pseudoholes, microholes, and schisis from myopia. Besides offering new insights into the pathogenesis of macular abnormalities, SD-OCT is a valuable tool for monitoring macular disease.
Clinical Results of Densiron 68 Intraocular Tamponade for Complicated Retinal Detachment
Authors: Li Wensheng , Zheng Qinxiang , Wang Xindan , Xu Ming , Wu Ronghan
Published: May 2010

Purpose:To assess the success rates and complications of Densiron 68 intraocular tamponade in the management of complicated retinal detachment (RD) with proliferative vitreoretinopathy (PVR). Methods:Twenty-one eyes of 20 patients with complicated RD and PVR were included in this prospective study. Vitreoretinal surgery with Densiron 68 intraocular tamponade was performed in all patients. Results:The success rate with 1 operation using Densiron 68 was 85.7%, and with further surgery 90.5%. Visual acuity improved from a mean logMAR of 2.25 (SD 0.73) to 1.19 (SD 0.88), p = 0.0001. There was little evidence of dispersion and excessive inflammation. Conclusion:According to the results of this study, vitreoretinal surgery with temporary Densiron 68 intraocular tamponade appears to increase the anatomical success and improve visual acuity, while giving rise to minimal complications, in selected cases of complicated RD and PVR.
Visual Acuity and Foveal Thickness after Vitrectomy for Macular Edema
Authors: Noma Hidetaka , Funatsu Hideharu , Mimura Tatsuya , Shimada Katsunori
Published: May 2010

The outcome of vitrectomy for macular edema was examined in patients with central retinal vein occlusion (CRVO), as well as whether vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) levels in vitreous fluid influence the visual prognosis and macular edema. Twenty-six consecutive patients with CRVO and macular edema underwent vitrectomy. Best-corrected visual acuity, retinal thickness, and the VEGF and IL-6 levels in vitreous fluid were measured before and after surgery. Both visual acuity and retinal thickness were significantly improved at 6 months postoperatively (p = 0.0114 and p < 0.0001, respectively). The vitreous VEGF level was significantly higher in patients who showed less improvement of visual acuity (p = 0.0182). In contrast, a high vitreous VEGF level was associated with greater improvement of macular edema (p = 0.0199). These results suggest that the vitreous VEGF level may be correlated with the visual prognosis and changes of macular edema in CRVO patients after vitrectomy.
Effect of Hydroxymethylglutaryl Coenzyme-A Reductase Inhibitors on the Long-Term Progression of Rheumatic Mitral Valve Disease
Authors: Antonini-Canterin Francesco , Moura Luis M. , Enache Roxana , Leiballi Elisa , Pavan Daniela , Piazza Rita , Popescu Bogdan A. , Ginghină Carmen , Nicolosi Gian Luigi , Rajamannan Nalini M.
Published: May 2010

Background—

At present, no medical therapy is known to affect the progression of rheumatic mitral stenosis (MS). We sought to assess the effect of statin treatment on long-term progression of MS in a large population.

Methods and Results—

From our 20-year database, we identified all patients with rheumatic MS with ≥2 echocardiographies ≥1 year apart. Exclusion criteria were previous intervention on the mitral valve, more than moderate aortic regurgitation, or symptoms at first examination. The study sample included 315 patients (mean age, 61±12 years; 224 women); 35 patients (11.1%) were treated with statins, and 280 (88.9%) were not. Mean follow-up period was 6.1±4.0 years (range, 1 to 20). The rate of decrease in mitral valve area was significantly lower in the statin group compared with the untreated group (0.027±0.056 versus 0.067±0.082 cm
2
/y;
P
=0.005). The annualized change in mean transmitral gradient was lower in statin-treated patients (0.20±0.59 versus 0.58±0.96 mm Hg/y;
P
=0.023). The prevalence of fast MS progression (annual change in mitral valve area >0.08 cm
2
) was significantly lower in the statin group (
P
=0.008). An increase in systolic pulmonary artery pressure of >10 mm Hg was found in 17% of patients in the statin group versus 40% of untreated patients (
P
=0.045).

Conclusions—

Our study shows a significantly slower progression of rheumatic MS in patients treated with statins. These findings could have an important impact in the early medical therapy of patients with rheumatic heart disease.
Natural History of Experimental Coronary Atherosclerosis and Vascular Remodeling in Relation to Endothelial Shear Stress
Authors: Koskinas Konstantinos C. , Feldman Charles L. , Chatzizisis Yiannis S. , Coskun Ahmet U. , Jonas Michael , Maynard Charles , Baker Aaron B. , Papafaklis Michail I. , Edelman Elazer R. , Stone Peter H.
Published: May 2010

Background—

The natural history of heterogeneous atherosclerotic plaques and the role of local hemodynamic factors throughout their development are unknown. We performed a serial study to assess the role of endothelial shear stress (ESS) and vascular remodeling in the natural history of coronary atherosclerosis.

Methods and Results—

Intravascular ultrasound-based 3-dimensional reconstruction of all major coronary arteries (n=15) was performed serially in vivo in 5 swine 4, 11, 16, 23, and 36 weeks after induction of diabetes mellitus and hyperlipidemia. The reconstructed arteries were divided into 3-mm-long segments (n=304). ESS was calculated in all segments at all time points through the use of computational fluid dynamics. Vascular remodeling was assessed at each time point in all segments containing significant plaque, defined as maximal intima-media thickness ≥0.5 mm, at week 36 (n=220). Plaque started to develop at week 11 and progressively advanced toward heterogeneous, multifocal lesions at all subsequent time points. Low ESS promoted the initiation and subsequent progression of plaques. The local remodeling response changed substantially over time and determined future plaque evolution. Excessive expansive remodeling developed in regions of very low ESS, further exacerbated the low ESS, and was associated with the most marked plaque progression. The combined assessment of ESS, remodeling, and plaque severity enabled the early identification of plaques that evolved to high-risk lesions at week 36.

Conclusions—

The synergistic effect of local ESS and the remodeling response to plaque formation determine the natural history of individual lesions. Combined in vivo assessment of ESS and remodeling may predict the focal formation of high-risk coronary plaque.
Involvement of Reductive Stress in the Cardiomyopathy in Transgenic Mice With Cardiac-Specific Overexpression of Heat Shock Protein 27
Authors: Zhang Xia , Min Xiaoyan , Li Chuanfu , Benjamin Ivor J. , Qian Bo , Zhang Xiaojin , Ding Zhengnian , Gao Xiang , Yao Yuzhen , Ma Yujie , Cheng Yunling , Liu Li
Published: May 2010

Oxidative stress plays an important role in cardiac diseases, which has been well demonstrated, whereas the role of reductive stress has been poorly investigated. We and others have shown previously that heat shock protein 27 (Hsp27) plays a role as an antioxidant. To investigate whether overexpression of Hsp27 could lead to reductive stress and result in cardiomyopathy, we generated transgenic mice with different expression levels of Hsp27. We observed that transgenic mice with high levels of Hsp27 developed cardiomyopathy. The myopathic hearts were under reductive stress, which was evidenced by an increased ratio of reduced glutathione/oxidized glutathione and a decreased level of reactive oxygen species. In addition, upregulated glutathione peroxidase 1 and decreased iron content were revealed in the myopathic hearts. More importantly, inhibition of glutathione peroxidase 1 significantly attenuated the development of cardiomyopathy. The data indicate that the Hsp27-induced cardiomyopathy could be attributed to, at least in part, upregulation of glutathione peroxidase 1. Our findings suggest that reductive stress plays an important role in the development of cardiomyopathy and that Hsp27 may serve as a potential target for the treatment of patients with cardiomyopathy.
Angiotensin II–Induced Vascular Smooth Muscle Cell Migration and Growth Are Mediated by Cytochrome P450 1B1–Dependent Superoxide Generation
Authors: Yaghini Fariborz A. , Song Chi Young , Lavrentyev Eduard N. , Ghafoor Hafiz U.B. , Fang Xiao R. , Estes Anne M. , Campbell William B. , Malik Kafait U.
Published: May 2010

Cytochrome P450 1B1, expressed in vascular smooth muscle cells, can metabolize arachidonic acid in vitro into several products including 12- and 20-hydroxyeicosatetraenoic acids that stimulate vascular smooth muscle cell growth. This study was conducted to determine whether cytochrome P450 1B1 contributes to angiotensin II–induced rat aortic smooth muscle cell migration, proliferation, and protein synthesis. Angiotensin II stimulated migration of these cells, measured by the wound healing approach, by 1.78-fold; and DNA synthesis, measured by [3H]thymidine incorporation, by 1.44-fold after 24 hours; and protein synthesis, measured by [3H]leucine incorporation, by 1.40-fold after 48 hours. Treatment of vascular smooth muscle cells with the cytochrome P450 1B1 inhibitor 2,4,3′,5′-tetramethoxystilbene or transduction of these cells with adenovirus cytochrome P450 1B1 small hairpin RNA but not its scrambled control reduced the activity of this enzyme and abolished angiotensin II– and arachidonic acid–induced cell migration, as well as [3H]thymidine and [3H]leucine incorporation. Metabolism of arachidonic acid to 5-, 12-, 15-, and 20-hydoxyeicosatetraenoic acids in these cells was not altered, but angiotensin II– and arachidonic acid–induced reactive oxygen species production and extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase activity were inhibited by 2,4,3′,5′-tetramethoxystilbene and cytochrome P450 1B1 small hairpin RNA (shRNA) and by Tempol, which inactivates reactive oxygen species. Tempol did not alter cytochrome P450 1B1 activity. These data suggest that angiotensin II–induced vascular smooth muscle cell migration and growth are mediated by reactive oxygen species generated from arachidonic acid by cytochrome P450 1B1 and activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase.
The Problem of Consumption
Authors: Dauvergne Peter
Published: May 2010

One of the biggest challenges for global environmental governance is “the problem of consumption.” The task involves far more than simply influencing what consumers choose, use, and discard. It requires a concerted effort to address the systemic drivers—including advertising, economic growth, technology, income inequality, corporations, population growth, and globalization—that shape the quantities, costs, and distribution of consumer goods. Current efforts to green consumption are “improving” management on many measures, such as per unit energy and resource use. Yet, this essay argues, such “progress” needs to be seen in the context of a rising global population and rising per capita consumption, where states and companies displace much of the costs of consumption far from those who are doing most of the consuming. This raises many questions about the value of sub-global measures for evaluating the environmental effectiveness of efforts to govern consumption. It also suggests the need for more global cooperation to mitigate the ecological effects of consumption. Current international initiatives such as the Marrakech process to draft a 10-Year Framework on “sustainable production and consumption,” however, will need to go well beyond simply promoting efficiencies, new technologies, and a greening of household consumption. Researchers in global environmental politics can assist here by probing even further into the complexity of governing the drivers and consequences of consumption, then working to thread these findings into the international policy process.
North Atlantic Subpolar Gyre Surface Variability (1895–2009)
Authors: Reverdin G.
Published: May 2010

Surface temperature, salinity, and density are examined in the northeastern part of the North Atlantic subpolar gyre over the last 115 years of measurements. This region presents coherent variability in space but also between different seasons, with relatively small trends and large multidecadal variability. The most significant trend is a lowering in surface density. Multidecadal variability in T and S is large and is usually similar, with the largest difference between the two in the 1920s and a tendency of T to lead S. Multidecadal T and S are correlated with the winter North Atlantic Oscillation (NAO) index at 0 or 1-yr lag for T and 0 to 3-yr lag for S. This suggests a strong contribution of advection. The lag between T and S is also suggestive of a contribution of air–sea fluxes of heat or freshwater, but probably more so at high frequencies than at the multidecadal time scales. Salinity higher frequency is correlated with NAO at a 2–3-yr lag, whereas T higher frequency variability presents no correlation with NAO at any lag. This suggests different relations between seasonal NAO indices and air–sea heat fluxes patterns in this region before and after 1960; also the advective signal is more clearly identified in salinity in this region.
Booms and Busts in the Deep
Authors: Farrell W. E. , Munk Walter
Published: May 2010

Deep sea (5 km) pressure and velocity at the Hawaii-2 Observatory (H2O), midway between Hawaii and California, exhibit a number of remarkable features that are interpreted using the Longuet–Higgins theory of acoustic radiation from oppositely directed surface waves. A change in the slope of the bottom spectra near 5 Hz can be associated with a transition near 2.5 Hz (25-cm wavelength) of the surface wave spectrum from the classical κ−4 saturated (wind independent) Phillips spectrum to a distinct band of ultragravity waves. Bottom spectra are remarkably stable. Occasional 15-dB busts in the gravities and booms in the ultragravities are prominent features in the bottom records and can be associated with calms and storms at the sea surface. For strong winds, two broad lobes in the directional spectrum of the gravity waves are nearly perpendicular to the wind; as the wind drops, the lobes become narrower and more nearly aligned with the wind, leading to busts.