bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal resource allocation for multicast flows in multihop wireless networks
Authors: Bui Loc , Srikant R. , Stolyar Alexander
Published: January 2008

Recently, the network utilization maximization theory has been extended to include resource allocation for multi-hop wireless networks. However, the existing theory is applicable only to unicast flows. Other than developing appropriate notations, it is somewhat straightforward to extend the theory to multicast flows if one assumes that data is delivered to all the receivers in a multicast group at the same rate. Such a form of multicast is called single-rate multicast. On the other hand, there are many video applications which allow layered-transmission so that different receivers can subscribe to different numbers of layers and receive different qualities of the same video, depending upon the congestion level in their respective neighborhoods. Moreover, in wireless networks, due to varying signal strengths at different receivers, it may not be desirable nor feasible to deliver data at the same rate to all the receivers in a multicast group. Thus, it is important to extend the optimization-based theory to handle multi-rate multicast flows, i.e., multicast flows where different receivers are allowed to receive at different rates. Such an extension is not straightforward as in the case of single-rate multicast, and is the main subject of this paper. We note that the multi-rate multicast problem has been considered in the context of wired network. However, those approaches cannot be directly applied to wireless networks.
Efficient resource allocation in bandwidth-sharing networks
Authors: Verloop Maaike , Núñez-Queija Rudesindo
Published: January 2008

Document transfer in the Internet is regulated by distributed packet-based congestion control mechanisms, usually relying on TCP. By dividing a document into packets, parts of one file reside at different nodes along the transmission path. The "instantaneous transfer rate" of the entire document can be thought of as being equal to the minimum transfer rate along the entire path. Bandwidth-sharing networks as considered by Massoulié & Roberts [2] provide a natural modeling framework for the dynamic flow-level interaction among document transfers. The class α-fair policies for such networks, as introduced by Mo & Walrand [3], captures a wide range of distributed allocation mechanisms such as TCP, the proportional fair allocation and the max-min fair allocation.
Stochastic models for web ranking
Authors: Volkovich Y. , Donato D. , Litvak N.
Published: January 2008

Web search engines need to deal with hundreds and thousands of pages which are relevant to a user's query. Listing them in the right order is an important and non-trivial task. Thus Google introduced
PageRank
[1] as a popularity measure for Web pages. Besides its primary application in search engines, PageRank also became a major method for evaluating importance of nodes in different informational networks and database systems.
Predicting the performance of internet-like networks using scaled-down replicas
Authors: Papadopoulos Fragkiskos , Psounis Konstantinos
Published: January 2008

The Internet is a large, heterogeneous system operating at very high speeds and consisting of a large number of users. Researchers use a suite of tools and techniques in order to understand the performance of complex networks like the Internet: measurements, simulations, and deployments on small to medium-scale testbeds. This work considers a novel addition to this suite: a class of methods to
scale down
the
topology
of the Internet that enables researchers to create and observe a smaller replica, and extrapolate its performance to the expected performance of the larger Internet.

The key insight that we leverage is that only the congested links along the path of each flow introduce sizable queueing delays and dependencies among flows. Hence, one might hope that the network properties can be captured by a topology that consists of the congested links only. We have verified this in [11, 12] using extensive simulations with TCP traffic and theoretical analysis. Further, we have also shown that simulating a scaled topology can be up to two orders of magnitude faster than simulating the original topology. However, a main assumption of our approach was that un-congested links are known in advance.

We are currently working on establishing rules that can be used to efficiently identify uncongested links in large and complex networks like the Internet, when these are not known, and which can be ignored when building scaled-down network replicas.
Global Calorie Counting: A Fitting Exercise for Obese Societies
Authors: Kumanyika Shiriki K.
Published: January 2008

Implementation of strategies to address obesity on a global scale has not yet begun in earnest. One key issue is uncertainty about the relative importance of taking aggressive action on the food vs. physical activity side of the energy balance equation, recognizing that interventions in both areas are critical. Using data on obesity prevalence, food availability, and selected economic and sociodemographic indicators from member countries of the Organization for Economic Cooperation and Development, an article in this volume of the Annual Review of Public Health provides estimates and projections to help resolve this uncertainty. The analyses presented support the authors' hypothesis that most of the recent rise in obesity is attributable to excess caloric intake. The implication that policies to curb overconsumption might include deliberate changes in the price structure of the food supply should stimulate debate about our current agricultural and trade paradigms, particularly because any such global policies would also affect the developing world.
Inhibition of MAPK Kinase Signaling Pathways Suppressed Renal Cell Carcinoma Growth and Angiogenesis In vivo
Authors: Huang Dan , Ding Yan , Luo Wang-Mei , Bender Stephanie , Qian Chao-Nan , Kort Eric , Zhang Zhong-Fa , VandenBeldt Kristin , Duesbery Nicholas S. , Resau James H. , Teh Bin Tean
Published: January 2008

The mitogen-activated protein kinase (MAPK) signaling pathways play essential roles in cell proliferation and differentiation. Recent studies also show the activation of MAPK signaling pathways in tumorigenesis, metastasis, and angiogenesis of multiple human malignancies, including renal cell carcinoma (RCC). To assess the role of this pathway in regulating the proliferation and survival of RCC cells, we first examined the expression of MAPK kinase (MKK) and MAPK in clear cell RCC and confirmed the overexpression of MKK1 and extracellular signal-regulated kinase 2 (ERK2) in these tumors. We then tested the effects of pharmacologic inhibition of MKK on human RCC cell lines, both in vitro and in vivo, using anthrax lethal toxin (LeTx), which cleaves and inactivates several MKKs. Western blotting showed that the phosphorylation levels of ERK, c-Jun-NH2 kinase, and p38 MAPK decreased after 72 h of LeTx treatment. Exposure to LeTx for 72 h reduced cell proliferation by 20% without significant effects on cell cycle distribution and apoptosis. Anchorage-independent growth of RCC cells was dramatically inhibited by LeTx. In vivo studies showed that tumor growth of RCC xenografts could be suppressed by LeTx. Extensive necrosis and decreased tumor neovascularization were observed after LeTx treatment. LeTx also showed direct inhibition of proliferation of endothelial cells in vitro. Our results suggest that suppression of one or more MAPK signaling pathways may inhibit RCC growth through the disruption of tumor vasculature. [Cancer Res 2008;68(1):81–8]
Loss and Reduction of Fus1 Protein Expression is a Frequent Phenomenon in the Pathogenesis of Lung Cancer
Authors: Prudkin Ludmila , Behrens Carmen , Liu Diane D. , Zhou Xian , Ozburn Natalie C. , Bekele B. Nebiyou , Minna John D. , Moran Cesar , Roth Jack A. , Ji Lin , Wistuba Ignacio I.
Published: January 2008

Purpose: FUS1, a novel tumor-suppressor gene located in the chromosome 3p21.3 region, may play an important role in lung cancer development. Currently, FUS1-expressing nanoparticles have been developed for treating patients with lung cancer. However, the expression of Fus1 protein has not been examined in a large series of lung cancers and their sequential preneoplastic lesions.

Experimental Design: Using tissue microarrays, we examined Fus1 immunohistochemical expression in 281 non–small cell lung carcinoma (NSCLC) and 22 small cell lung carcinoma tissue specimens and correlated the findings with patients' clinicopathologic features. To investigate the expression of Fus1 in the early sequential pathogenesis of NSCLC, we studied Fus1 expression in 211 histologically normal and mildly abnormal bronchial epithelia, and 118 bronchial and alveolar preneoplastic lesions obtained from patients with lung cancer.

Results: Loss and reduction of expression was detected in 82% of NSCLCs and 100% of small cell lung carcinomas. In NSCLCs, loss of Fus1 immunohistochemical expression was associated with significantly worse overall survival. Bronchial squamous metaplastic and dysplastic lesions expressed significantly lower levels of Fus1 compared with normal (P = 0.014 and 0.047, respectively) and hyperplastic (P = 0.013 and 0.028, respectively) epithelia.

Conclusions: Our findings show a high frequency of Fus1 protein loss and reduction of expression in lung cancer, and suggests that this reduction may play an important role in the early pathogenesis of lung squamous cell carcinoma. These findings support the concept that FUS1 gene and Fus1 protein abnormalities could be used to develop new strategies for molecular cancer therapy for a significant subset of lung tumors.
Modeling of Two Northwest Atlantic Storms with Third-Generation Wave Models
Authors: Padilla-Hernández R. , Perrie W. , Toulany B. , Smith P. C.
Published: January 2008

In this study, three state-of-the-art operational forecast wave models are implemented on nested grids in order to achieve fine-resolution wave simulations (0.1°) in the Gulf of Maine and related northwest Atlantic waters. These models are the Simulating Waves Nearshore (SWAN) model, the Wave Action Model (WAM), and WAVEWATCH-III (hereafter WW3). Model performance is evaluated through comparisons with field measurements. Four composite model systems are compared: WAM and WW3 implemented on three nested domains, SWAN nested within WAM, and SWAN nested within WW3. Storm case studies include two intense midlatitude winter storms from January 2000 and January 2002. Although the models are comparable in terms of their overall performance and skill, it is found that WW3 provides a better statistical fit to the observed wave data compared with the other models, and that SWAN gives slightly better results if nested within WW3, rather than within WAM.
Níveis de irrigação e doses de potássio sobre os teores foliares de nutrientes do maracujazeiro amarelo
Authors: Sousa Valdemício F. de , Foleggatti Marcus V. , Frizzone José A. , Dias Thiago J. , Albuquerque Júnior Boanerges S. , Batista Erasmo C.
Published: January 2008

Este trabalho foi realizado com o objetivo de avaliar o efeito de níveis de irrigação e doses de potássio aplicadas via água de irrigação por gotejamento, sobre os teores foliares de nutrientes do maracujazeiro amarelo. O trabalho foi desenvolvido no Campo Experimental da Fazenda Areão, da ESALQ/USP, em Piracicaba, SP (22° 42' 30" S e 47° 38' 00" W); utilizou-se, com tal propósito, um delineamento experimental de blocos ao acaso com quatro repetições, cujos tratamentos foram arranjados no esquema de parcelas subdivididas e resultaram da combinação de quatro níveis de irrigação (L1 = 0,25 L; L2 = 0,50 L; L3 = 0,75 L; L4 = 1,00 L) em que L é o volume de água médio medido em lisímetros, e cinco níveis de potássio (K0 = 0,000; K1 = 0,225; K2 = 0,450; K3 = 0,675 e K4 = 0,900 kg planta-1 ano-1 de K2O), aplicadas via água de irrigação. Avaliou-se a concentração de nutrientes nas plantas através da diagnose foliar, realizada no período de colheita de frutos. Os teores dos nutrientes nas folhas do maracujazeiro não foram influenciados pelos níveis de irrigação nem pela interação irrigação x potássio, ao passo que a acumulação de K, Ca, Mg, B e Mn o foram pelas doses de potássio.
The Proportion of Ontario Gambling Revenue Derived from Problem Gamblers
Authors: Williams Robert J. , Wood Robert T.
Published: January 2008

The proportion of gambling revenue derived from problem gamblers is an important issue when considering the appropriateness of government-sponsored gambling. Figures obtained from prior research are tentative due to methodological problems and the mismatch between reported expenditures and actual gambling revenue. Using improved methods for assessing the prevalence of problem gambling and the accuracy of self-reported gambling expenditures, the present study estimates that the 4.8 percent of problem gamblers in Ontario in 2003 accounted for approximately 36 percent of Ontario gambling revenue. This proportion varied as a function of game type, with a lower proportion for lotteries, instant win tickets, bingo, and raffles, and a higher proportion for horse racing and slot machines.
Decolorizing kinetics of reactive black SRE by UV/TiO2
Authors: Xu Hang , Zhang Dongxiang , Xu Wenguo , Li Hansheng , Du Meng
Published: January 2008

Photocatalysis with TiO2 (UV/TiO2) was employed to treat Reactive Black SRE (RB SRE) in aqueous solution. The effects of TiO2 loading, initial concentration of RB SRE and pH on the photocatalytic activity were investigated. The RB SRE degradation intermediate products were analyzed by ultraviolet visible spectrum (UV–vis), gas chromatography‐mass spectrometry (GC‐MS), and ion chromatography (IC). The results show the optimum TiO2 loading was 0.15 g L−1 and acidic medium could improve the removal of RB SRE, and the rise of RB SRE initial concentration decreased color removal. The main intermediate products were 2,5‐diritrobenzoic acid and 3,5,5‐trimethylhexanoic acid. The primary inorganic ions were Cl−, NO, and SO. The photocatalytic degradation rate followed pseudo‐first order at different loadings of TiO2 and initial concentrations of RB SRE. On the basis of Langmuir model, the limiting rate of the reaction at maximum coverage (kv) and the equilibrium constant for adsorption (Ke) of RB SRE are 1.129 mg L−1 min−1 and 0.01789 L mg−1, respectively. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
A relational–XML data warehouse for data aggregation with SQL and XQuery
Authors: Fong Joseph , Shiu Herbert , Cheung Davy
Published: January 2008

Integrating information from multiple data sources is becoming increasingly important for enterprises that partner with other companies for e‐commerce. However, companies have their internal business applications deployed on diverse platforms and no standard solution for integrating information from these sources exists. To support business intelligence query activities, it is useful to build a data warehouse on top of middleware that aggregates the data obtained from various heterogeneous database systems. Online analytical processing (OLAP) can then be used to provide fast access to materialized views from the data warehouse. Since extensible markup language (XML) documents are a common data representation standard on the Internet and relational tables are commonly used for production data, OLAP must handle both relational and XML data. SQL and XQuery can be used to process the materialized relational and XML data cubes created from the aggregated data. This paper shows how to handle the two kinds of data cubes from a relational–XML data warehouse using extract, transformation and loading. Copyright © 2008 John Wiley & Sons, Ltd.
Decreased glucose transporters correlate to abnormal hyperphosphorylation of tau in Alzheimer disease
Authors: Liu Ying , Liu Fei , Iqbal Khalid , Grundke-Iqbal Inge , Gong Cheng-Xin
Published: January 2008

Brain glucose uptake/metabolism is impaired in Alzheimer disease (AD). Here, we report that levels of the two major brain glucose transporters (GLUT1 and GLUT3) responsible for glucose uptake into neurons were decreased in AD brain. This decrease correlated to the decrease in O‐GlcNAcylation, to the hyperphosphorylation of tau, and to the density of neurofibrillary tangles in human brains. We also found down‐regulation of hypoxia‐inducible factor 1, a major regulator of GLUT1 and GLUT3, in AD brain. These studies provide a possible mechanism by which GLUT1 and GLUT3 deficiency could cause impaired brain glucose uptake/metabolism and contribute to neurodegeneration via down‐regulation of O‐GlcNAcylation and hyperphosphorylation of tau in AD.
Savanna fires govern community structure of ungulates in Bénoué National Park, Cameroon
Authors: Klop Erik , van Goethem Janneke
Published: January 2008

We studied the effects of savanna fires on the structure of local ungulate communities in a West African woodland savanna. The distribution of 11 ungulate species over 9−15 burned sites (the number of which increased as burning activity continued during the dry season) and 7−13 unburned sites was compared with a variety of null models or randomized ‘virtual communities’. Five different parameters of community structure were examined: body mass distribution, co-occurrence patterns, species richness, species density and guild dominance. Overall, ungulate species were not randomly distributed over burned and unburned sites. The regular spacing of body masses in the set of species recorded on burned and unburned sites indicated competition, since species similar in body mass are more likely to compete than species of different size. However, co-occurrence patterns on burned sites were random, indicating absence of competition at fine spatial scales due to differential habitat use within the burned landscape. Although the attractiveness of the regrowth on burned sites resulted in higher numbers of ungulates compared with unburned sites, species richness was not different. Grazers were the dominant guild on burned sites, but there were no differences in species richness or species density between grazers and browsers on unburned sites.
An evolutionary multiobjective strategy for the effective management of groundwater resources
Authors: Giustolisi O. , Doglioni A. , Savic D. A. , di Pierro F.
Published: January 2008

This paper introduces a modeling approach aimed at the management of groundwater resources based on a hybrid multiobjective paradigm, namely Evolutionary Polynomial Regression. Multiobjective modeling in hybrid evolutionary computing enables the user (a) to find a set of feasible symbolic models, (b) to make a robust choice of models and (c) to improve computational efficiency, simultaneously developing a set of models with diverse structural parsimony levels. Moreover, this methodology appears to be well suited to those cases where process input and the boundary conditions are not easily accessible. The multiobjective approach is based on the Pareto dominance criterion and it is fully integrated into the Evolutionary Polynomial Regression paradigm. This approach proves to be effective for modeling groundwater systems, which usually requires (a) accurate analyses of the underlying physical phenomena, (b) reliable forecasts under different hypothetical scenarios and (c) good generalization features of the models identified. For these reasons it is important to construct easily interpretable models which are specialized for well defined purposes. The proposed methodology is tested on a case study aimed at determining the dynamic relationship between rainfall depth and water table depth for a shallow unconfined aquifer located in southeast Italy.
Anomalous behavior of soil mantle groundwater demonstrates the major effects of bedrock groundwater on surface hydrological processes
Authors: Kosugi Ken'ichirou , Katsura Shin'ya , Mizuyama Takahisa , Okunaka Suemi , Mizutani Tasuku
Published: January 2008

The formation of groundwater in the soil mantle has a dominant effect on rainwater discharge and shallow landslide occurrence in headwater catchments. Here, we report two completely different groundwater responses within a single well excavated into the soil mantle. One was an ephemeral‐type response that is well described by physical hydrology models based on a geographic information system (GIS). The other was a semi‐perennial‐type response, rarely reported in previous studies, which cannot be explained by the existing physical models. The semi‐perennial groundwater caused considerably high antecedent groundwater tables between storms, leading to an increased peak in the groundwater level during later heavy storm events and a likely increase in the risk of shallow landslides. Moreover, peaks in the semi‐perennial groundwater lagged considerably behind rainstorm events, which probably affected base flow discharge by forming a delayed peak. Geochemical and geothermal observations indicated that the source of the semi‐perennial groundwater was deep bedrock groundwater, demonstrating the considerable effects of bedrock groundwater on surface hydrological processes.
Interface properties of Pb∕InAs planar structures for Andreev spectroscopy
Authors: Magnus F. , Yates K. A. , Clowes S. K. , Miyoshi Y. , Bugoslavsky Y. , Cohen L. F. , Aziz A. , Burnell G. , Blamire M. G. , Josephs-Franks P. W.
Published: January 2008

For Andreev spectroscopy to be a useful tool to detect spin accumulation in semiconductors, we show by simulation that there is a maximum value for the interface scattering parameter that can be tolerated. Three different fabrication routes for Pb∕InAs planar junctions are explored and we find that the “etch-back” processing strategy is the most promising. Using the parameters extracted from the spectroscopic analysis, we find that the interface properties fall into four different regimes of behavior.
Cyclotron mass of two-dimensional holes in (100) oriented GaAs∕AlGaAs heterostructures
Authors: Lu T. M. , Li Z. F. , Tsui D. C. , Manfra M. J. , Pfeiffer L. N. , West K. W.
Published: January 2008

Microwave cyclotron resonance of low-density high-mobility two-dimensional hole gases of different densities in (100) oriented GaAs∕AlGaAs heterostructures has been measured at 4.2K. The measurements show that the hole effective mass depends strongly on the confining potential. For holes in a 20nm quantum well, the cyclotron mass decreases from 0.48me at density p=6.9×1010∕cm2 to 0.29me at p=0.8×1010∕cm2. The cyclotron mass for holes confined at a heterojunction is fairly insensitive to the density and has a value of approximately 0.5me.
p21
Cip1
restricts neuronal proliferation in the subgranular zone of the dentate gyrus of the hippocampus
Authors: Pechnick Robert N. , Zonis Svetlana , Wawrowsky Kolja , Pourmorady Jonathan , Chesnokova Vera
Published: January 2008

The subgranular zone (SGZ) of the dentate gyrus of the hippocampus is a brain region where robust neurogenesis continues throughout adulthood. Cyclin-dependent kinases (CDKs) have a primary role in controlling cell division and cellular proliferation. p21
Cip1
(p21) is a CDK inhibitor that restrains cell cycle progression. Confocal microscopy revealed that p21 is abundantly expressed in the nuclei of cells in the SGZ and is colocalized with NeuN, a marker for neurons. Doublecortin (DCX) is a cytoskeletal protein that is primarily expressed by neuroblasts. By using FACS analysis it was found that, among DCX-positive cells, 42.8% stained for p21, indicating that p21 is expressed in neuroblasts and in newly developing neurons. p21-null (
p21
−/−
) mice were examined, and the rate of cellular proliferation, as measured by BrdU incorporation, was increased in the SGZ of
p21
−/−
compared with WT mice. In addition, the levels of both DCX and NeuN protein were increased in
p21
−/−
mice, further demonstrating increased hippocampal neuron proliferation. Chronic treatment with the tricyclic antidepressant imipramine (10 mg/kg per day i.p. for 21 days) markedly decreased hippocampal p21 mRNA and protein levels, produced antidepressant-like behavioral changes in the forced swim test, and stimulated neurogenesis in the hippocampus. These results suggest that p21 restrains neurogenesis in the SGZ and imipramine-induced stimulation of neurogenesis might be a consequence of decreased p21 expression and the subsequent release of neuronal progenitor cells from the blockade of proliferation. Because many antidepressants stimulate neurogenesis, it is possible that their shared common mechanism of action is suppression of p21.
A single Hox locus in Drosophila produces functional microRNAs from opposite DNA strands
Authors: Stark Alexander , Bushati Natascha , Jan Calvin H. , Kheradpour Pouya , Hodges Emily , Brennecke Julius , Bartel David P. , Cohen Stephen M. , Kellis Manolis
Published: January 2008

MicroRNAs (miRNAs) are ∼22-nucleotide RNAs that are processed from characteristic precursor hairpins and pair to sites in messages of protein-coding genes to direct post-transcriptional repression. Here, we report that the miRNA iab-4 locus in the Drosophila Hox cluster is transcribed convergently from both DNA strands, giving rise to two distinct functional miRNAs. Both sense and antisense miRNA products target neighboring Hox genes via highly conserved sites, leading to homeotic transformations when ectopically expressed. We also report sense/antisense miRNAs in mouse and find antisense transcripts close to many miRNAs in both flies and mammals, suggesting that additional sense/antisense pairs exist.
MicroRNAs in the Drosophila bithorax complex
Authors: Bender Welcome
Published: January 2008

The iab-4 noncoding RNA from the Drosophila bithorax complex is the substrate for a microRNA (miRNA). Gene conversion was used to delete the hairpin precursor of this miRNA; flies homozygous for this deletion are sterile. Surprisingly, this mutation complements with rearrangement breakpoint mutations that disrupt the iab-4 RNA but fails to complement with breaks mapping in the iab-5 through iab-7 regulatory regions. These breaks disrupt the iab-8 RNA, transcribed from the opposite strand. This iab-8 RNA also encodes a miRNA, detected on Northern blots, derived from the hairpin complementary to the iab-4 precursor hairpin. Ultrabithorax is a target of both miRNAs, although its repression is subtle in both cases.
Preservation in early vascular plants
Authors: EDWARDS DIANNE
Published: January 2008

The colonisation of the land by plants and the origin of vascular plants were events that changed the face of our planet and are as captivating to the imagination as they are controversial. The plants themselves were morphologically very simple and their fossils lack the aesthetic appeal of the famous fronds of the Coal Measures, yet quite remarkable cellular detail can be observed at the microscopic level.
Displaying geological 3‐D surfaces using computer graphics
Authors: SOWERBUTTS W. T. C.
Published: January 2008

Now that increasing quantities of geological information are being handled by computer, computer graphic techniques are being used more and more to display the information in graphical form. In this article I show that computer graphic techniques for displaying surfaces have applications in many branches of geology.
Charles Darwin's geologist's field guide
Authors: WILDING RICHARD
Published: January 2008

From observations carried out on his ‘Beagle’ voyage, Charles Darwin made a number of important contributions to geological science. He showed himself to be a meticulous observer and an imaginative field worker. His methods are probably best summarized in a contribution on field geology that he made to the Admiralty Manual of Scientific Enquiry, published in 1849. That paper contains some important clues for the historian of early nineteenth‐century geology.
Detectives and geology in fiction ‐ 2: After the Golden Age
Authors: SARJEANT WILLIAM A. S.
Published: January 2008

Following the‘Golden Age’of Holmes and Thorndyke, geology and geological phenomena have figured in quite a number of crime novels. In a handful, geologists even serve as central characters — or as victims. These novels are here identified and briefly discussed, while the lack of a geologist as 'series character’is lamented.
COMPARISON OF THE EFFECTS OF ULTRAVIOLET RADIATION ON THE INTRACELLULAR CATALASE OF AEROBIC AND ANAEROBIC YEAST
Authors: Kaplan J. G.
Published: January 2008

Abstract— Suspensioris of aerobic and anaerobic yeast were subjected to ultraviolet radiation (principally 254 mµ) under closely comparable experimental conditions, and changes in the level and in the temperature dependence of their catalase activity were determined. Qualita tively, the effects of U.V. on the enzyme of the anaerobic cells were similar to those on that of the aerobic cells. The effect of U.V. on the anaerobic catalase differed from that on the aerobic enzyme in the following respects: I, a considerably greater dose of U.V. was necessary in order to attain the maximum activity and the minimum activation energy of the enzyme‐substrate system; 2, a far greater dose was required before appreciable photoinactivation of the maxi mally active enzyme occurred; 3, photoinactivation proceeded at less than one‐half the rate; 4, the u.v.‐induced increase in the catalase activity of the suspension was virtually complete before appreciable reduction in activation energy occured. The first three of these differences were interpreted in terms of a model, which pictures the anaerohic catalase as being tightly bound to an intracellular chromophore group.
MECHANISM OF ENZYME INACTIVATION BY ULTRAVIOLET LIGHT AND THE PHOTOCHEMISTRY OF AMINO ACIDS (AT 2537 Å)*
Authors: Luse R. A. , McLaren A. D.
Published: January 2008

Abstract— >The inactivation of the enzymes chymotrypsin, lysozyme, ribonuclease, and trypsin by ultraviolet light can be accounted for quantitatively by summing the products of (1) the probability that light is absorbed by a given amino acid residue, the molecular extinc tion coefficient, and (2) the probability that absorbed light induces a chemical change in the residue, the quantum yield for the residue. The principal residues involved are cystyl and tryptophanyl. Peptide bond rupture is not important. Energy transfer among chromophores within molecules of enzymes need not be invoked in order to account for photochemical inactivation.

Quantum yields for the destruction of a number of amino acids at 2537 A have been measured.
QUESTIONS REGARDING THE PRESUMED ROLE OF THYMINE DIMER IN PHOTOREACTIVABLE U.V. DAMAGE TO DNA*
Authors: Rupert Claud S.
Published: January 2008

Summary A large volume of compelling evidence has indicated thymine dimer as the principal photoreactivable ultraviolet damage in DNA. Some experiments with the photoreactivating enzyme system clash with this interpretation. Several varieties of thymine dimer containing compound fail to interact with photoreactivating enzyme, while u.v. irradiated polydeoxy GC, a polynucleotide lacking thymine, carries a photoenzymatically reactive product. Photoreactivable u.v. damage does not form in DNA during irradiation below pH 3–3.5, while dimerization of thymine in a simpler compound does. Some evidence, which at first glance seems to support the dimer hypothesis, fails under scrutiny, and may even weigh against it.
SPECTRAL RESPONSES TO LIGHT BY UNICELLULAR PLANTS*
Authors: Pirson A. , Kowallik W.
Published: January 2008

Summary Synchronized cultures of Chlorella show marked differences in cellular composition when grown in blue and red light at equal net production (dry weight). Cells from blue light always have a higher content in protein and RNA, while cells in red are relatively rich in total carbohydrates. The spectral effect responsible for this difference is independent of the nitrogen source used. Other effects of blue light (vs. red) are: a permanent delay of the cell division, and a transient reduction in DNA synthesis; prolonged culture in blue overcomes the latter inhibition.
LIGHT‐INDUCED ABSORBANCY CHANGES IN EIMHJELLEN'S RHODOPSEUDOMONAS*
Authors: Holt A. S. , Clayton Roderick K.
Published: January 2008

Abstract— Light induced absorbancy changes in Rhodopseudomonas sp. NHTC 133 are analogous to those observed in other photosynthetic bacteria, but all of the features in the light‐induced difference spectrum (except those reflecting cytochrome oxidation) are shifted to greater wavelengths. This general shift is consistent with the fact that the bacteriochlorophyll of this organism (BChl b) differs from the usual BChl in that its absorption bands are shifted to greater wavelengths.

The singlet excited state of P985 (the counterpart of the P870 of Rhodopseudomonas spheroides) is not an energy sink relative to the major component of BChl b in vivo. The absorption maximum of P985 is at 985 mp, whereas that of CBhl b in vivo is at 1012 mμ.
EFFECTS OF DOSE FRACTIONATION ON ULTRAVIOLET SURVIVAL OF ESCHERICHIA COLI
Authors: Harm Walter
Published: January 2008

Abstract— Exposure of E. coli B/r and B at low average dose rates of u.v. radiation (2537 Å), produced either by fractionated doses or by continuous irradiation at a very low dose rate (80 ergs/mm2/hr), results in much increased survival compared to single exposure at high dose rate. This increase is attributed to repair taking place during the irradiation period. The effect is small in the repair‐deficient strains E. coli B8‐1_, and C syn‐, and is absent in phage T1 and T4, which cannot undergo repair in the extracellular state. However, the prolonged time available for repair in these experiments accounts for only a very minor part of the increase in survival. The principal factor apparently is that the number of lesions present at any time remains relatively low. Presumably complete repair, not only the excision step, can occur in buffer during the irradiation period. This interpretation is supported by experiments in which cells were exposed to combinations of highly fractionated irradiation and single‐dose irradiation. We therefore propose that mutual interference in repair, possibly by overlapping of repair regions in complementary DNA strands, reduces considerably the repair efficiency if many lesions are present. This hypothesis explains the ‘shouldered’ survival curves of B/r and possibly other E. coli strains as due to decreasing repair efficiency with increasing u.v. dose
APPLICATIONS OF ELECTRONIC ENERGY TRANSFER IN SOLUTION*,†
Authors: Lamola Angelo A.
Published: January 2008

Abstract— lntermolecular transfer of electronic energy is a powerful tool for obtaining information about excited molecules in solution. Proper application of excitation transfer requires giving careful attention to the spectroscopic properties of the donor and acceptor and accounting for all possible donor‐acceptor interactions of consequence. Water presents no particular difficulties so that electronic energy transfer methods can be applied to the photochemistry of biologically important molecules in aqueous solvents.
SPECTROSCOPIC BEHAVIOR OF ALL‐TRANS RETINAL AND ITS SCHIFF BASES IN VARIOUS MEDIA. THE ROLE OF CONFORMATIONAL PERTURBATION
Authors: IRVING C. S. , LEERMAKERS P. A.
Published: January 2008

Se ha encontrado que la n‐all‐trans‐retinilideno‐n‐butilamina tiene propiedades espectroscópicas, absorción y emisión similares a las de la meta rodopsina I que as un intermediario en la fotólisis del pigmento visual rodopsina. La sensibilidad se presenta solamente cuando el compuesto modelo es adsorbido en silica gel o cuando se lo disuelve en metanol a 77°K. Se describen evidencias espectroscópicas a baja temperature lo cual indica que prelumi o lumirodopsina son artefactos que probablemente no juegan un rol importante en la respuesta visual.
Response to Comment on "Protein Sequences from Mastodon and
Tyrannosaurus rex
Revealed by Mass Spectrometry"
Authors: Asara John M. , Schweitzer Mary H.
Published: January 2008

We sequenced six endogenous collagen peptides from
Tyrannosaurus rex
bone fragments using mass spectrometry. Five sequences match birds, but only two match amphibians, supporting dinosaur-bird relationships. Buckley
et al.
reinterpret and misinterpret our data and question sequence authenticity, but they used a suboptimal phylogenetic algorithm to analyze only a subset of reported sequences and they suggest analyses that are less sensitive and less specific than mass spectrometry. We disagree and use data to explain.
Early diagnosis of autism through analysis of pre-speech vocalizations
Authors: Dai Keshi
Published: January 2008

Autism is a complex neurodevelopmental disorder that typically appears before age of three years old. The narrower term of autism always refers to classic autistic disorder in the spectrum of pervasive developmental disorder (PDD). In this paper, "autism" and "autistic" are all used to refer to the entire range of autism spectrum disorders (ASD).
Stimulation of UT-A1-mediated transepithelial urea flux in MDCK cells by lithium
Authors: Fröhlich Otto , Aggarwal Deepak , Klein Janet D. , Kent Kimilia J. , Yang Yuan , Gunn Robert B. , Sands Jeff M.
Published: January 2008

Trans-epithelial tracer urea flux across Madin-Darby canine kidney (MDCK) cells permanently expressing the urea transporter UT-A1 is stimulated by agents that activate the cAMP signaling pathway, such as vasopressin or forskolin, thus mimicking the activation of urea permeability in the inner medullary collecting duct in the presence of vasopressin. Here, we report that UT-A1-mediated urea flux is also activated two-to-threefold over background by exposing the cells to media containing LiCl. This is in contrast to reports on cortical and medullary collecting duct tubules where acute and chronic exposure to lithium (Li) suppresses the osmotic water permeability, which is also regulated by cAMP levels. The Li concentration dependence of urea flux activation was linear up to 150 mM Li. Li activated only from the basolateral side where its effect was inhibited by amiloride, presumably because Li entered the cells through a basolateral Na-H exchanger. Li and IBMX, which also weakly activated urea flux, greatly augmented each others' stimulatory effect on urea flux. However, cellular cAMP levels did not rise commensurately with urea fluxes, and even though Li augments the activation by forskolin, it greatly inhibits the forskolin-induced formation of cAMP. These results suggest that the effect of Li in this MDCK model of renal cells does not involve cAMP or at least utilizes an additional signaling pathway independent of cAMP.
20-HETE-mediated cytotoxicity and apoptosis in ischemic kidney epithelial cells
Authors: Nilakantan Vani , Maenpaa Cheryl , Jia Guangfu , Roman Richard J. , Park Frank
Published: January 2008

20-HETE, a metabolite of arachidonic acid, has been implicated as a mediator of free radical formation and tissue death following ischemia-reperfusion (IR) injury in the brain and heart. The present study examined the role of this pathway in a simulated IR renal injury model in vitro. Modified self-inactivating lentiviral vectors were generated to stably overexpress murine Cyp4a12 following transduction into LLC-PK1cells (LLC-Cyp4a12). We compared the survival of control and transduced LLC-PK1cells following 4 h of ATP depletion and 2 h of recovery in serum-free medium. ATP depletion-recovery of LLC-Cyp4a12 cells resulted in a significantly higher LDH release ( P < 0.05) compared with LLC-enhanced green fluorescent protein (EGFP) cells. Treatment with the SOD mimetic MnTMPyP (100 μM) resulted in decreased cytotoxicity in LLC-Cyp4a12 cells. The selective 20-HETE inhibitor HET-0016 (10 μM) also inhibited cytotoxicity significantly ( P < 0.05) in LLC-Cyp4a12 cells. Dihydroethidium fluorescence showed that superoxide levels were increased to the same degree in LLC-EGFP and LLC-Cyp4a12 cells after ATP depletion-recovery compared with control cells and that this increase was inhibited by MnTMPyP. There was a significant increase ( P < 0.05) of caspase-3 cleavage, an effector protease of the apoptotic pathway, in the LLC-Cyp4a12 vs. LLC-EGFP cells ( P < 0.05). This was abolished in the presence of HET-0016 ( P < 0.05) or MnTMPyP ( P < 0.01). These results demonstrate that 20-HETE overexpression can significantly exacerbate the cellular damage that is associated with renal IR injury and that the programmed cell death is mediated by activation of caspase-3 and is partially dependent on enhanced CYP4A generation of free radicals.
Hypoxia Regulates Choline Kinase Expression through Hypoxia-Inducible Factor-1α Signaling in a Human Prostate Cancer Model
Authors: Glunde Kristine , Shah Tariq , Winnard Paul T. , Raman Venu , Takagi Tomoyo , Vesuna Farhad , Artemov Dmitri , Bhujwalla Zaver M.
Published: January 2008

The intensity of the total choline (tCho) signal in spectroscopic images of tumors is spatially heterogeneous. The likewise heterogeneous physiologic tumor microenvironment may contribute to this heterogeneity. We therefore investigated the relationship between hypoxia, choline metabolites, and choline kinase (Chk) in a human prostate cancer model. Human PC-3 prostate cancer cells were engineered to express enhanced green fluorescent protein (EGFP) under hypoxic conditions. These PC-3-5HRE-EGFP cells were characterized in culture and as tumors transplanted in mice using 1H magnetic resonance spectroscopy (MRS) and MRS imaging (MRSI) combined with EGFP fluorescence microscopy and imaging. Hypoxic EGFP-fluorescing tumor regions colocalized with regions of high tCho in combined MRSI and optical imaging studies. Cellular phosphocholine (PC) and tCho concentrations as well as Chk expression levels significantly increased following exposure of PC-3 cells to hypoxia. A putative promoter region located 5′ of the translation start site of the human chk-α gene was cloned and luciferase (Luc)-based reporter vector constructs were generated. Luc reporter assays provided evidence that some of the putative hypoxia response elements (HRE) within this putative chk-α promoter region functioned in vitro. Chromatin immunoprecipitation assays using an antibody against hypoxia-inducible factor (HIF)-1α showed that HIF-1 can directly bind this region of the endogenous chk-α promoter in hypoxic PC-3-5HRE-EGFP cells. These data suggest that HIF-1 activation of HREs within the putative chk-α promoter region can increase Chk-α expression within hypoxic environments, consequently increasing cellular PC and tCho levels within these environments. [Cancer Res 2008;68(1):172–80]
Antitumor Effects of Systemically Delivered Adenovirus Harboring Trans-Splicing Ribozyme in Intrahepatic Colon Cancer Mouse Model
Authors: Jeong Jin-Sook , Lee Seong-Wook , Hong Seung-Hee , Lee Yoon-Jong , Jung Haeng-Im , Cho Kyung-Sook , Seo Hye-Hyun , Lee Sang-Jin , Park Sohee , Song Min-Sun , Kim Chang-Min , Kim In-Hoo
Published: January 2008

Purpose: Our previous studies suggested that human telomerase reverse transcriptase (hTERT) RNA-targeting trans-splicing ribozyme could be a useful tool for cancer gene therapy. Here, we investigated whether adenoviruses harboring this ribozyme can be systemically delivered to mice, and whether they selectively mark tumors expressing hTERT and sensitize them to ganciclovir treatments.

Experimental Design: We constructed adenoviral vectors containing modified hTERT-targeting trans-splicing ribozyme with downstream reporter gene (Ad-Ribo-LacZ) or suicide gene (Ad-Ribo-HSVtk) driven by a cytomegalovirus promoter. The tumor-specific trans-splicing reaction and the tumor-killing effect of adenoviruses harboring ribozyme were investigated both in vitro and in vivo using mice with intrahepatic colon cancer metastasis via systemic administration. The safety of systemic administration of the viruses was also evaluated.

Results: We showed that Ad-Ribo-LacZ, when injected i.v., performs a highly specific trans-splicing reaction on hTERT mRNA and that it selectively marks tumors expressing hTERT in mice. More importantly, i.v. injection of Ad-Ribo-HSVtk plus ganciclovir significantly reduced tumor burden, with minimal liver toxicity, in mice with metastatic liver cancer, compared with the untreated group (P = 0.0009). Moreover, animals receiving Ad-Ribo-HSVtk showed improved survival compared with controls (P < 0.0001).

Conclusions: This study shows that systemically delivered adenovirus harboring trans-splicing ribozyme can recognize cancer-specific transcripts and reprogram them to combat the cancer cells. Use of trans-splicing ribozymes seems to be a potentially useful gene therapy for cancer.
Electronic Alerts Versus On-Demand Decision Support to Improve Dyslipidemia Treatment
Authors: van Wyk Jacobus T. , van Wijk Marc A.M. , Sturkenboom Miriam C.J.M. , Mosseveld Mees , Moorman Peter W. , van der Lei Johan
Published: January 2008

Background—

Indirect evidence shows that alerting users with clinical decision support systems seems to change behavior more than requiring users to actively initiate the system. However, randomized trials comparing these methods in a clinical setting are lacking. We studied the effect of both alerting and on-demand decision support with respect to screening and treatment of dyslipidemia based on the guidelines of the Dutch College of General Practitioners.

Methods and Results—

In a clustered randomized trial design, 38 Dutch general practices (77 physicians) and 87 886 of their patients (39 433 men 18 to 70 years of age and 48 453 women 18 to 75 years of age) who used the ELIAS electronic health record participated. Each practice was assigned to receive alerts, on-demand support, or no intervention. We measured the percentage of patients screened and treated after 12 months of follow-up. In the alerting group, 65% of the patients requiring screening were screened (relative risk versus control=1.76; 95% confidence interval, 1.41 to 2.20) compared with 35% of patients in the on-demand group (relative risk versus control=1.28; 95% confidence interval, 0.98 to 1.68) and 25% of patients in the control group. In the alerting group, 66% of patients requiring treatment were treated (relative risk versus control=1.40; 95% confidence interval, 1.15 to 1.70) compared with 40% of patients (relative risk versus control=1.19; 95% confidence interval, 0.94 to 1.50) in the on-demand group and 36% of patients in the control group.

Conclusion—

The alerting version of the clinical decision support systems significantly improved screening and treatment performance for dyslipidemia by general practitioners.
Atlantic Major Hurricanes, 1995–2005—Characteristics Based on Best-Track, Aircraft, and IR Images
Authors: Zehr Raymond M. , Knaff John A.
Published: January 2008

The Atlantic major hurricanes during the period of 1995–2005 are examined using best-track data, aircraft-based observations of central pressure, and infrared (IR) satellite images. There were 45 Atlantic major hurricanes (Saffir–Simpson category 3 or higher) during this 11-yr period, which is well above the long-term average. Descriptive statistics (e.g., average, variability, and range) of various characteristics are presented, including intensity, intensification rate, major hurricane duration, location, storm motion, size, and landfall observations. IR images are shown along with IR-derived quantities such as the digital Dvorak technique intensity and IR-defined cold cloud areas. In addition to the satellite intensity estimates, the associated component IR temperatures are documented. A pressure–wind relationship is evaluated, and the deviations of maximum intensity measurements from the pressure–wind relationship are discussed.

The Atlantic major hurricane activity of the 1995–2005 period distinctly exceeds the long-term average; however, the average location where major hurricanes reach maximum intensity has not changed. The maximum intensity for each 1995–2005 Atlantic major hurricane is given both as the highest maximum surface wind (Vmax) and the lowest minimum sea level pressure (MSLP). Comparisons are made to other Atlantic major hurricanes with low MSLP back to 1950. Maximum 24-h intensification rates average 21.1 m s−1 day−1 and range up to 48.8 m s−1 day−1 in terms of Vmax. The largest 24-h MSLP decreases average 34.2 hPa and range from 15 to 97 hPa. Major hurricane duration averages 2.7 days with a maximum of 10 days. Hurricane size, as given by the average radius of gale force wind at maximum intensity, averages 250.8 km and has an extremely large range from 92.5 to 427.4 km.