bluuebunny/crossref_metadata_2025 huggingface dataset:
CE separation of proteins and yeasts dynamically modified by PEG pyrenebutanoate with fluorescence detection
Authors: Horká Marie , Růžička Filip , Holá Veronika , Šlais Karel
Published: June 2007

The optimized protocols of the bioanalytes separation, proteins and yeasts, dynamically modified by the nonionogenic tenside PEG pyrenebutanoate, were applied in CZE and CIEF with the acidic gradient in pH range 2–5.5, both with fluorescence detection. PEG pyrenebutanoate was used as a buffer additive for a dynamic modification of proteins and/or yeast samples. The narrow peaks of modified analytes were detected. The values of the pI's of the labeled proteins were calculated using new fluorescent pI markers in CIEF and they were found to be comparable with pI's of the native compounds. As an example of the possible use of the suggested CIEF technique, the mixed cultures of yeasts, Candida albicans, Candida glabrata, Candida kefyr, Candida krusei, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Candida zeylanoides, Geotrichum candidum, Saccharomyces cerevisiae, Trichosporon asahii and Yarrowia lipolytica, were reproducibly focused and separated with high sensitivity. Using UV excitation for the on‐column fluorometric detection, the minimum detectable amounts of analytes, femtograms of proteins and down to ten cells injected on the separation capillary, were estimated.
Autofocusing and ESI‐MS analysis of protein digests in a miniaturized multicompartment electrolyzer
Authors: Tomáš Roman , Yan Liushui , Křenková Jana , Foret František
Published: June 2007

Free‐solution IEF of protein digests was studied in a newly introduced MicroRotofor™ multicompartment electrolyzer. The fractionation was performed in a cylindrical separation chamber divided into ten compartments with or without the addition of carrier ampholytes. In the case of autofocusing mode of operation, the tryptic digest itself served as the mixture of ampholytes leading to the separation of the peptides with well‐defined pI's. The focusing process was monitored visually using colored pI markers. The resulting fractions from both modes of the separation were analyzed by CE and electrospray‐TOF mass spectrometer using electrospray tips microfabricated in polyimide. Additional experiments, aiming at visualization of the mass flux within the focusing compartments were performed using isotachophoretic migration of color cationic tracers. The study considered the autofocusing of both the peptides with well‐defined narrow pI's as well as those showing negligible net charge in a broader pH range. Although not all peptides in the protein digests have well‐defined pI's the autofocusing process can preseparate many of them leading to higher S/N in the ESI‐MS signals and improved protein sequence coverage.
A plea for more careful presentation of near‐surface air temperature data in geomorphology
Authors: Holden Joseph
Published: June 2007

Geomorphologists often provide near‐surface air temperature data for their study sites in publications. This is usually in the form of mean annual or monthly temperature. Inspection of papers in Earth Surface Processes and Landforms for 2004, 2005 and 2006 has shown that the source of these data is usually not given. Problems arise because scientists derive ‘mean temperature’ in different ways, which do not give the same result. It is suggested that a protocol is followed when presenting near‐surface air temperature data for journal publication as part of site descriptions or results. Copyright © 2007 John Wiley & Sons, Ltd.
Recent behaviour of the Debeli Namet glacier, Durmitor, Montenegro
Authors: Hughes Philip. D.
Published: June 2007

A small cirque glacier is present in a north‐east facing cirque on the mountain of Šljeme (2455 m a.s.l.) in the Durmitor massif, Montenegro. Sediment ridges in front of this glacier are interpreted as moraines and can be attributed to recent glacier activity over the past 130 years. Lichenometry was applied to determine the relative ages of different moraines using Aspicilia calcarea agg. One set of moraines dates from about 1878 AD, whilst another set of inner moraines dates from about 1904 AD. The most recent moraines appear to have formed within the last 11 years in front of an active glacier margin. Copyright © 2007 John Wiley & Sons, Ltd.
Bank permeability in an Australian ephemeral dry‐land stream: variation with stage resulting from mud deposition and sediment clogging
Authors: Dunkerley David L.
Published: June 2007

Percolation of flood waters into the bed and banks of ephemeral streams provides one of the key mechanisms responsible for transmission loss. However, there are very few published estimates of the rates at which water can enter stream‐bank sediments, and little is known about the variation in bank permeability with elevation above the bed and the resulting effects on transmission loss in floods of different magnitudes. This paper presents the results of 69 field determinations of bank infiltrability made on Fowlers Creek, an ephemeral dry‐land stream located in arid western New South Wales, Australia. Fowlers Creek carries high concentrations of suspended sediments, which are deposited as mud drapes on the bed, banks and floodplain. Results demonstrate that infiltration rates are lowest at the base of the banks, and tend to increase steadily with elevation on the bank, even above the apparent upper limit of mud drapes. In parallel, the texture of the bank sediments (assessed from samples of the uppermost 10 cm) becomes coarser with elevation above the bed. This pattern is inferred to relate to the delivery of silts and clays into pore spaces in the bank sediments by percolating flood waters. The patterns of infiltration rate and sediment texture mapped in the field are reasoned to be the product of many clogging episodes in past flood events having different peak stages. The increase in infiltration rate and mean particle size up the banks reflects lower frequencies of submergence and clogging of the upper banks by large floods, and more frequent inundation and clogging of the lower banks by sub‐bank‐full flows. The stage‐related changes in bank permeability provide a mechanism that can drive variations in transmission loss among floods having different peak stages and hydrograph shapes. Copyright © 2007 John Wiley & Sons, Ltd.
Enhanced opportunistic beamforming scheme for practical broadcast systems
Authors: Bosisio R. , Vicario J. L. , Spagnolini U. , Anton‐Haro C.
Published: June 2007

In multiantenna systems the optimisation of linear spatial precoding is severely hampered by the amount of feedback. A practical solution consists in the opportunistic beamforming (OB), which randomly generates the beamforming and schedules the user with the largest signal‐to‐noise ratio (SNR). In this paper we investigate the benefits that can be provided by the knowledge of the users spatial covariance at the transmitter. We enhance the OB scheme by matching the beamforming generation to the users channels spatial patterns. We analytically assess the performance of the proposed scheme, referred to as Cluster‐Eigenbeamforming (Cluster‐EB), both in ideal (perfect feedback) and in practical scenario (imperfect feedback). Cluster‐EB is shown to outperform the conventional schemes and the performance gain increases in practical systems as Cluster‐EB capitalises on the spatial covariance knowledge to reduce the sensitivity with respect to the feedback imperfections. Copyright © 2007 John Wiley & Sons, Ltd.
A sustainability assessment of a health equity fund initiative in Cambodia
Authors: Jacobs Bart , Price Neil , Sam Sam Oeun
Published: June 2007

All but one of the health equity funds (HEFs) currently operating in Cambodia, introduced to address the adverse effects of low user fee exemption rates, rely heavily on external funding and have high administrative overheads. This article reports on a study of one type of HEF, based in Kirivong Operational Health District (KOD) and operated through local pagoda structures, which demonstrates minimal reliance on external funding and low administrative overheads. We utilize an adapted sustainability assessment framework to assess the ability of pagoda structures to enable financial access for the poorest to public sector health services. We further analyse the strengths and limitations of the pagoda‐managed equity fund initiative, with a view to assessing not only its sustainability but its potential for replication in other settings.

Our study shows that, against key sustainability indicators (health service utilization and health outcomes; management capacity and financial viability; community mobilization and government support), the pagoda‐managed equity fund initiative scores well. However, it is evident that some external financial support is needed to allow the HEFs to function effectively. We conclude with recommendations for replicating the initiative, which include working innovatively with indigenous grassroots organizations to enhance community HEF ownership and to keep administrative overheads low. Copyright © 2007 John Wiley & Sons, Ltd.
Secret image transmission based on VQ and data embedding
Authors: Shie Shih‐Chieh , Lin Shinfeng D.
Published: June 2007

A new secret image transmission scheme suitable for narrow communication channel is proposed in this article. A set of secret images can be simultaneously and efficiently delivered to the receiver via a small and meaningless data stream by the proposed scheme. To reduce the volume of secret images, a codebook is first generated and these secret images are encoded into binary indexes based on the vector quantization (VQ) technique. The compressed message is then embedded into the VQ codebook utilized in the encoding procedure by an adaptive least‐significant‐bits (LSB) modification technique. For the purpose of security, the slightly modified codebook is further encrypted into a meaningless data stream by the AES cryptosystem. Simulation results show that the proposed scheme provides an impressive improvement both in the visual quality of the extracted secret images at the receiver and in the hiding capacity of the cover medium. Experimental data also reveal the feasibility of the proposed secret image transmission scheme for limited‐bandwidth environment. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 1–9, 2007
A new automated delineation method for SPECT lung scans using adaptive dual‐exponential thresholding
Authors: Wang Alex , Yan Hong
Published: June 2007

An accurate method for delineating lung contours in single photon emission computed tomography (SPECT) is critical to respiratory studies such as pulmonary embolism (PE) and respiratory aerosol deposition. Current delineation methods are not adaptive in nature and may require a priori information on lung volumes. We have developed a dual‐exponential thresholding method that solely requires SPECT scans, and is fast, accurate, and adaptive in nature. A dataset consisted of 90 patients was studied retrospectively. While most were suspected of PE, other pulmonary disorders were also present. SPECT ventilation scans were obtained after inhalation of ∼40 MBq of 99mTc‐Technegas. Examination of the corresponding natural logarithmically transformed histograms revealed dual exponential functions like pattern. Adaptive thresholds were found as the intercept between the two exponential functions. 350 Monte Carlo simulations representative of normally‐ventilated scans with varying counts were used to quantitatively measure and evaluate the method. Our method correctly delineated lung volumes to above 97% agreement for 310 of the 350 Monte Carlo simulations with maximum count values greater than or equal to 31. The 40 low‐count simulations were included purely as extreme cases. For real patient scenario, an experienced physician was called upon to visually delineate a sample of 50 actual patient scans, and these delineated lung volumes were used as gold standard and compared with those delineated using our method. Our results had an average of 96% agreement. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 22–27, 2007
User‐friendly image sharing using polynomials with different primes
Authors: Yang Ching‐Nung , Yu Kun‐Hsuan , Lukac Rastislav
Published: June 2007

Recently, Thien and Lin proposed a user‐friendly (k, n)‐threshold scheme which employs Lagrange interpolation to produce shadow images representing a shrunken version of the original image. In this paper, we introduce a new framework which uses more (k − 1)‐degree polynomials with different primes to enhance the functionality of the user‐friendly (k, n)‐threshold framework and obtain more effective performance for large k. Since the proposed framework significantly reduces reconstruction errors compared to the previously published user‐friendly schemes, it is suitable for modern visual communication applications where features such as distributed trust, secure transmission and storage, fault tolerance, and high‐quality image reconstruction are required. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 40–47, 2007
Cadmium accumulation and binding characteristics in intact Sertoli/germ cell units, and associated effects on stage‐specific functions in vitro: insights from a shark testis model
Authors: McClusky Leon M.
Published: June 2007

The increased human use of cadmium (Cd) and its increased occurrence in the environment is of concern. The testis is sensitive to Cd because of the steroid‐mediated regulation of spermatogenesis, high levels of DNA synthesis and gene transcription, all of which varies in a stage‐related manner. Validated techniques (acridine orange vital staining to detect apoptosis and dextran‐rhodamine exclusion to assess blood–testis barrier function) were recently developed and the shark testis was proposed as an alternative model for assessing stage‐specific functions in living testicular tissue and to study toxicant actions on spermatogenesis. The present paper shows that 109Cd accumulation and binding in vitro was stage‐dependent (premeiotic, PrM > meiotic, M > postmeiotic, PoM), rapid and persisted in spermatocysts (intact germ cell/Sertoli cell units) 49 h after washout. In competitive binding analyses of all three spermatocyst stages, Hg, but not Zn, could replace bound 109Cd, suggesting that Cd binding was specific. These findings were associated with a biphasic apoptotic response in the PrM spermatocysts, which was maximal at 10 µm CdCl2 and 1 µm CdCl2 after 2 and 4 days in culture, respectively. Although Cd uptake in PoM cysts was more than 2‐fold less than uptake in PrM cysts, the percentage dextran‐rhodamine permeant PoM cysts was ∼8‐fold greater than in controls in the presence of both 10 µm CdCl2 and 30 µm CdCl2 after 4 days culture, indicating that blood–testis barrier function in PoM spermatocysts was compromised. These findings demonstrate that this model has utility for use in screening assays of environmental toxicants. Copyright © 2007 John Wiley & Sons, Ltd.
Antibiotic multiresistance strictly associated with IS256 and ica genes in Staphylococcus epidermidis strains from implant orthopedic infections
Authors: Montanaro Lucio , Campoccia Davide , Pirini Valter , Ravaioli Stefano , Otto Michael , Arciola Carla Renata
Published: June 2007

In this study the presence both of the ica genes, encoding for biofilm exopolysaccharide production, and the insertion sequence IS256, a mobile element frequently associated to transposons, was investigated in relationship with the prevalence of antibiotic resistance among Staphylococcus epidermidis strains. The investigation was conducted on 70 clinical isolates derived from orthopedic implant infections. Among the clinical isolates investigated a dramatic high level of association was found between the presence of ica genes as well as of IS256 and multiple‐resistance to all the antibiotics tested (oxacillin, penicillin, gentamicin, erythromycin, clindamycin, chloramphenicol, sulfamethoxazole + trimethoprim, ciprofloxacin, vancomycin). Noteworthy, a striking full association between the presence of IS256 and resistance to gentamicin was found, being none of the IS256‐negative strain resistant to this antibiotic. This association is probably because of the link of the corresponding aminoglycoside‐resistance genes, and IS256, often co‐existing within the same staphylococcal transposon. In conclusion, in orthopedics, the presence of ica genes and that of IS256 in S. epidermidis genome should both be considered as informative markers of clinically relevant strains equipped with greatest and broadest resistance potential to survive to medical treatments. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Effect of acidic degradation products of poly(lactic‐co‐glycolic)acid on the apatite‐forming ability of poly(lactic‐co‐glycolic)acid‐siloxane nanohybrid material
Authors: Rhee Sang‐Hoon , Lee Seung Jin
Published: June 2007

The effect of poly(lactic‐co‐glycolic) acid (PLGA) degradation products on the apatite‐forming ability of a PLGA‐siloxane nanohybrid material were investigated. Two PLGA copolymer compositions with low and high degradability were used in the experiment. The PLGA‐siloxane nanohybrid materials were synthesized by end‐capping PLGA with acid end‐groups using 3‐isocyanatopropyl triethoxysilane following the sol–gel reaction with calcium nitrate tetrahydrate. Two nanohybrid materials that had different degradability were exposed to simulated body fluid (SBF) for 1–28 days at 36.5°C. The low degradable PLGA hybrid showed apatite‐forming ability within 3 days of incubation while the high degradable one did not within 28 days testing period. The results were explained in terms of the acidity of the PLGA degradation products, which could directly influence on the apatite dissolution. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Influence of hydroxyl content on selected properties of 45S5 bioactive glass
Authors: Hall Matthew M.
Published: June 2007

Numerous material properties may be influenced by the concentration of chemically dissolved hydroxyl species within a glass. A tube furnace connected to a steam generator was used to create hydroxyl‐saturated 45S5 glass under 1 atm of water at 1100°C. Selected properties of as‐melted and hydroxyl‐saturated samples were compared to assess the sensitivity of 45S5 to excess hydroxylation. The glass transition temperature and the peak crystallization temperature of the treated 45S5 glass were reduced in comparison to the as‐melted 45S5 glass. In addition, the treated glass exhibited a broad endothermic signal that may be indicative of enhanced viscous flow. A simple dissolution experiment indicated that the treated 45S5 glass was also less durable than the as‐melted 45S5 glass. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Structure, depolymerization, and cytocompatibility evaluation of glycol chitosan
Authors: Knight Darryl K. , Shapka Stephen N. , Amsden Brian G.
Published: June 2007

Glycol chitosan, a water soluble chitosan derivative being investigated as a new biomaterial, was fractionated via two different methods. Initial characterization of the glycol chitosan with 1H NMR spectroscopy illustrated the presence of both secondary and tertiary amine groups, contradictory to its widely accepted structure. Fractionation of glycol chitosan with nitrous acid resulted in a significant reduction in the number average molecular weight, specifically, from 170 to ∼7 kDa for a pH 3 and below. However, the reaction altered its chemical structure, as the secondary amine groups were converted to N‐nitrosamines, which are potentially carcinogenic. An increase in the pH of the reaction limited this formation, but not entirely. Free radical degradation initiated with potassium persulfate was not as effective at reducing the molecular weight as the nitrous acid approach, yielding molecular weights around 12 kDa under the same molar ratio of degrading species, but did retain the structural integrity of the glycol chitosan. Additionally, control of the molecular weight appears feasible with potassium persulfate. When assessed in vitro for cytocompatibility, the polymer exhibited no toxicity on monolayer‐cultured chondrocytes, and in fact stimulated cell growth at low concentrations. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Quick‐forming hydroxyapatite/agarose gel composites induce bone regeneration
Authors: Watanabe Junji , Kashii Masafumi , Hirao Makoto , Oka Kunihiro , Sugamoto Kazuomi , Yoshikawa Hideki , Akashi Mitsuru
Published: June 2007

We investigated the fundamental properties of quick‐forming hydroxyapatite (HAp)/agarose gel composites, and evaluated their potential as an injectable bone substitute. From scanning electron microscope observations, the HAp/agarose gel composites produced by an innovative electrophoretic process showed an interconnecting structure with the HAp particles. The diameter of the HAp particles was roughly 1 μm, and the total amount of HAp particles was estimated by a quantification of the calcium ions. In the case of 1 mg of dry composite, 10 μg of HAp was formed in the agarose gel. Moreover, X‐ray diffraction analysis revealed that the HAp particles had an amorphous structure, so the HAp particles were expected to dissolve under physiological conditions relative to the HAp with higher crystallinity. The advantages of the resultant HAp/agarose gel composites are ease of handling, close contact with the surrounding tissues, and ease of use as an injectable material. As a preliminary animal study, the composites were implanted into the medial femoral condyle of rabbits. After implantation, the process of bone regeneration was evaluated by microfocus‐computed tomography (μCT) and histological analysis. At 2 weeks postoperatively, newly‐formed bone was observed at the edge of the bone defect site, and at 4 weeks postoperatively, excellent bone regeneration was observed. The implanted composite gradually degraded, and disappeared at 8 weeks postoperatively. This result indicated that the composite dissolved rapidly, and was replaced by newly‐formed bone. Quick‐forming HAp/agarose gel composites may be a good candidate as an injectable biomaterial, particularly in the fields of orthopedic, oral, and maxillofacial surgery. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
The most widespread desmosomal cadherin, desmoglein 2, is a novel target of caspase 3‐mediated apoptotic machinery
Authors: Cirillo Nicola , Lanza Michele , De Rosa Alfredo , Cammarota Marcella , La Gatta Annalisa , Gombos Fernando , Lanza Alessandro
Published: June 2007

Apoptotic cells are known to regulate the ordered dismantling of intercellular contacts through caspase activity. Despite the important role of desmoglein (Dsg) 2 in epithelial cell–cell adhesion, the fate of this widespread desmosomal cadherin during apoptosis is yet poorly understood. Here, by means of pharmacological approaches, we investigated whether Dsg2 was targeted by caspases in HaCaT and HT‐29 cell lines undergoing staurosporine (STS)‐induced apoptosis. Results showed that STS induced a caspase‐dependent form of cell‐death in both keratinocytes (HaCaT) and enterocytes (HT‐29), that associated with progressive depletion of Dsg2 from cell lysates. The proteolytic processing of full‐length Dsg2 resulted in the appearance of a 70‐kDa fragment which was released into the cytosol. Consistently, immunofluorescence studies revealed that Dsg2 staining was abolished from cell surface whereas the cytoplasmic region of Dsg2 did localize intracellularly. Plakoglobin (Pg) also underwent cleavage and detached from Dsg2. Apoptotic changes paralleled with progressive loss of intercellular adhesion strength. All these biochemical, morphological, and functional changes were regulated by caspase 3. Indeed, in the presence of the caspase 3‐inhibitor z‐DEVD‐fmk, full‐length Dsg2 protein levels were preserved, whereas the amount of the 70‐kDa fragment was maintained on control levels. Furthermore, cells pretreated with z‐DEVD‐fmk retained the membrane labeling of Dsg2. Taken together, our data demonstrate that the apoptotic processing of Dsg2 is mediated by caspase 3 in epithelial cells. J. Cell. Biochem. 103: 598–606, 2008. © 2007 Wiley‐Liss, Inc.
Ab initio study of electronic structure and optical properties of heavy‐metal azides: TlN3, AgN3, and CuN3
Authors: Zhu Weihua , Xiao Heming
Published: June 2007

Detailed ab initio studies on the electronic structure and optical properties of the heavy‐metal azides have been performed using density functional theory within the generalized gradient approximation. An analysis of band structure, density of states, charge transfer, and bond order shows that the heavy‐metal azides are ionic compounds but have covalent character. The valence bands of AgN3 and CuN3 are strongly dominated by Ag‐ and Cu‐d, respectively, but that of TlN3 arises from the contributions of Tl‐s and terminal N‐p and not from Tl‐d. The real and imaginary parts of the dielectric function, adsorption coefficient, and electron energy‐loss spectra are calculated and compared with available experimental data. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Symmetry operation measures
Authors: Pinsky Mark , Casanova David , Alemany Pere , Alvarez Santiago , Avnir David , Dryzun Chaim , Kizner Ziv , Sterkin Alexander
Published: June 2007

We introduce a new mathematical tool for quantifying the symmetry contents of molecular structures: the Symmetry Operation Measures. In this approach, we measure the minimal distance between a given structure and the structure which is obtained after applying a selected symmetry operation on it. If the given operation is a true symmetry operation for the structure, this distance is zero; otherwise it gives an indication of how different the transformed structure is from the original one. Specifically, we provide analytical solutions for measures of all the improper rotations, S, including mirror symmetry and inversion, as well as for all pure rotations, C. These measures provide information complementary to the Continuous Symmetry Measures (CSM) that evaluate the distance between a given structure and the nearest structure which belongs to a selected symmetry point‐group. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Direct dynamics study on the reaction of acetaldehyde with ozone
Authors: Yang Jing , Li Qian Shu , Zhang Shaowen
Published: June 2007

The hydrogen abstraction reaction of ozone with acetaldehyde has been studied theoretically over the temperature range 250–2500 K. Two different reactive sites of acetaldehyde molecule, CH3 and CHO groups have been investigated, and results confirm that the CHO group is a highly reactive site. In this study, the geometries and harmonic vibrational frequencies of all stationary points are calculated at the MPW1K, BHandHLYP, and MPWB1K levels of theory. The minimum energy paths (MEPs) were obtained at the MPW1K/6‐31+G(d,p) level of theory. To refine the energies along the MEPs of each channel, single‐point energy calculations were performed by a higher‐level energy calculation method (denoted as HL). The rate constants were evaluated based on the MEPs from the HL method in the temperature range 250–2500 K by using the conventional transition state theory (TST), the canonical variational transition state theory (CVT), the microcanonical variational transition state theory (μVT), the CVT coupled with small‐curvature tunneling (SCT) correction (CVT/SCT), and the μVT coupled with Eckart tunneling correction (μVT/Eckart). The fitted three‐parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CHO group are kCVT/SCT(T) = 4.92 × 10−27·T3.77·e(−7867.0/T) and kμVT/Eckart(T) = 2.10 × 10−27·T3.90·e(−7706.2/T), respectively. The fitted three‐parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CH3 group are kCVT/SCT(T) = 1.27 × 10−27·T3.94·e(−14554.1/T) and kμVT/Eckart(T) = 1.62 × 10−26·T3.66·e(−15459.8/T), respectively. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Ang II and EGF synergistically induce COX‐2 expression via CREB in intestinal epithelial cells
Authors: Pham Hung , Chong Benny , Vincenti Romina , Slice Lee W.
Published: June 2007

Cyclooxygenase (COX)‐2 derived prostaglandins (PGs) play a major role in intestinal inflammation and colorectal carcinogenesis. Because COX‐2 is the rate‐limiting step in the production of PGs, mechanisms that regulate COX‐2 expression control PG production in the cell. Using the non‐tumorigenic, rat intestinal epithelial cell, IEC‐18, we demonstrate that co‐activation of endogenously expressed AT1 receptor and EGFR resulted in synergistic expression of COX‐2 mRNA and protein involving transcriptional and post‐transcriptional mechanisms. Ang II and EGF induced transient phosphorylation of ERK, p38MAPK and CREB. Co‐stimulation with Ang II and EGF prolonged phosphorylation of ERK, p38MAPK, and CREB. The p38MAPK selective inhibitor, SB202190, but not the MEK selective inhibitor, PD98059, or the EGFR kinase inhibitor, AG1478, inhibited Ang II‐dependent COX‐2 expression and CREB phosphorylation. EGF‐dependent COX‐2 expression and CREB phosphorylation were inhibited by SB202190, PD98059, and AG1478. Inhibition of CREB expression using two separate RNAi methods blocked COX‐2 expression by Ang II and EGF. Expression of a dominant negative CREB mutant inhibited Ang II‐ and EGF‐dependent induction of the COX‐2 promoter. Ang II induced luciferase expression in cells transfected with the CRE‐luc reporter vector and cells co‐transfected with Gal4‐luc reporter vector and a Gal4‐CREB expression vector. Chromatin immunoprecipitation assays demonstrated CREB binding to the proximal rat COX‐2 promoter region containing a CRE cis‐acting element. These results indicate that co‐stimulation with Ang II and EGF synergistically induced COX‐2 expression in these intestinal epithelial cells through p38MAPK mediated signaling cascades that converge onto CREB. J. Cell. Physiol. 214:96–109, 2008. © 2007 Wiley‐Liss, Inc.
Claudin‐16 is directly phosphorylated by protein kinase a independently of a vasodilator‐stimulated phosphoprotein‐mediated pathway
Authors: Ikari Akira , Ito Midori , Okude Chiaki , Sawada Hayato , Harada Hitoshi , Degawa Masakuni , Sakai Hideki , Takahashi Tadanobu , Sugatani Junko , Miwa Masao
Published: June 2007

Claudin‐16 (CLDN‐16) is involved in the paracellular reabsorption of Mg2+ in the thick ascending limb of Henle. The tight junctional localization and Mg2+ transport of CLDN‐16 are regulated by cAMP/PKA‐dependent phosphorylation. Here, we examined whether PKA phosphorylates CLDN‐16 in a direct or indirect manner. CLDN‐16 was stably expressed in Madin‐Darby canine kidney (MDCK) cells using a Tet‐OFF system. The phosphorylation of CLDN‐16 is upregulated by fetal calf serum (FCS). This phosphorylation was completely inhibited by a PKA inhibitor, N‐[2‐(p‐bromocinnamylamino)ethyl]‐5‐isoquinolinesulfonamide dihydrochloride. Without FCS, dibutyryl cAMP (DBcAMP) increased the phosphoserine level of CLDN‐16 in a concentration‐dependent manner. The phosphorylated CLDN‐16 elicited increases of transepithelial electrical resistance (TER) and transepithelial transport of Mg2+. Vasodilator‐stimulated phosphoprotein (VASP) was also phosphorylated in the presence of FCS or DBcAMP. In the glutathione‐S‐transferase (GST) pull down assay, a cytosolic carboxyl domain of CLDN‐16 was associated with PKA, but not with VASP. Furthermore, PKA was immunoprecipitated with CLDN‐16 in MDCK cells, but VASP was not. In cells expressing a dephosphorylated mutant (Ser160Ala) of VASP, CLDN‐16 was phosphorylated by DBcAMP and was associated with ZO‐1, a tight junctional‐scaffolding protein, without integral cell–cell junctions. We suggest that PKA directly phosphorylates CLDN‐16, resulting in the localization to tight junctions (TJs) and the maintenance of Mg2+ reabsorption. J. Cell. Physiol. 214:221–229, 2008. © 2007 Wiley‐Liss, Inc.
Representations of graphs and orthogonal latin square graphs
Authors: Erdös Paul , Evans Anthony B.
Published: June 2007

We define graph representations modulo integers and prove that any finite graph has a representation modulo some integer. We use this to obtain a new, simpler proof of Lindner, E. Mendelsohn, N. Mendelsohn, and Wolk's result that any finite graph can be represented as an orthogonal latin square graph.
Binding number and minimum degree for k‐factors
Authors: Tokushige Norihide
Published: June 2007

In this paper, we study mixed conditions on the binding number and the minimum degree of a graph G that guarantee the existence of a k‐factor in G. Among others, we prove that a graph G of order n with δ(G) ⩾ cn and bind(G) > (2 − 3c)/(1 − c), where c is any fixed number, has a 2‐factor.
On the number of hamilton cycles in a random graph
Authors: Cooper C. , Frieze A. M.
Published: June 2007

Let a random graph G be constructed by adding random edges one by one, starting with n isolated vertices. We show that with probability going to one as n goes to infinity, when G first has minimum degree two, it has at least (log n) distinct hamilton cycles for any fixed ϵ>0.
Almost every graph has reconstruction number three
Authors: Bollobás Béla
Published: June 2007

The paper contains a proof of the conjecture of Harary and Plantholt, stated in the title.
Bounds for the vertex linear arboricity
Authors: Matsumoto Makoto
Published: June 2007

The vertex linear arboricity vla(G) of a nonempty graph G is the minimum number of subsets into which the vertex set V(G) can be partitioned so that each subset induces a subgraph whose connected components are paths. This paper provides an upper bound for vla(G) of a connected nonempty graph G, namely vla(G) ≦ 1 + ⌊δ(G)/2⌋ where δ(G) denotes the maximum degree of G. Moreover, if δ(G) is even, then vla(G) = 1 + ⌊δ(G)/2⌋ if and only if G is either a cycle or a complete graph.
The edge reconstruction of hamiltonian graphs
Authors: Pyber L.
Published: June 2007

If a graph G on n vertices contains a Hamiltonian path, then G is reconstructible from its edge‐deleted subgraphs for n sufficiently large.
Hamiltonian circuits in N2‐locally connected K1,3‐free graphs
Authors: Ryjáček ZdeněK
Published: June 2007

There are many results concerned with the hamiltonicity of K1,3‐free graphs. In the paper we show that one of the sufficient conditions for the K1,3‐free graph to be Hamiltonian can be improved using the concept of second‐type vertex neighborhood. The paper is concluded with a conjecture.
A note on Ki‐perfect graphs
Authors: Brown Jason I. , Corneil Derek G. , Mahjoub A. Ridha
Published: June 2007

Ki‐perfect graphs are a special instance of F ‐ G perfect graphs, where F and G are fixed graphs with F a partial subgraph of G. Given S, a collection of G‐subgraphs of graph K, an F ‐ G cover of S is a set of T of F‐subgraphs of K such that each subgraph in S contains as a subgraph a member of T. An F ‐ G packing of S is a subcollection S′⊆ S such that no two subgraphs in S′ have an F‐subgraph in common. K is F ‐ G perfect if for all such S, the minimum cardinality of an F ‐ G cover of S equals the maximum cardinality of an F ‐ G packing of S. Thus Ki‐perfect graphs are precisely Ki‐1 ‐ Ki perfect graphs. We develop a hypergraph characterization of F ‐ G perfect graphs that leads to an alternate proof of previous results on Ki‐perfect graphs as well as to a characterization of F ‐ G perfect graphs for other instances of F and G.
Path‐isomorphic networks
Authors: Hartvigsen David
Published: June 2007

Two source‐sink (directed) networks are called path‐isomorphic if there exists a bijection π between their arc sets that preserves (simple) source‐sink directed paths. Although path‐isomorphic networks need not be isomorphic (they need not even have the same number of nodes), we show that several properties are preserved. For example, suppose N and N′ are path‐isomorphic. Then, N is acyclic if and only if N′ is acyclic. B is the arc set of block of N if and only if π(B) is the arc set of a block of N′. Also, D is the arc set of a dicomponent of N if and only if π(D) is the arc set of a dicomponent of N′. In addition, we prove a dipath version of Whitney's well‐known 2‐isomorphism theorem for a special class of networks, which includes the acyclic networks.
On the decomposition of Kn into complete m‐partite graphs
Authors: Huang Qingxue
Published: June 2007

Graham and Pollak [3] proved that n −1 is the minimum number of edge‐disjoint complete bipartite subgraphs into which the edges of Kn can be decomposed. Using a linear algebraic technique, Tverberg [2] gives a different proof of that result. We apply his technique to show that for “almost all n,” ⌊ (n + m −3)/(m −1) ⌋ is the minimum number of edge‐disjoint complete m‐partite subgraphs in a decomposition of Kn.
An upper bound on the ramsey number R(K3, G) depending only on the size of the graph G
Authors: Sidorenko A. F.
Published: June 2007

Harary stated the conjecture that for any graph G with n edges and without isolated vertices r(K3,G) ⩽ 2n + 1. Erdös, Faudree, Rousseau, and Schelp proved that r(K3,G) ⩽ ⌈8/3n⌉. Here we prove that r(K3,G) ⩽ ⌊5/2n⌋ −1 for n > 3.
Long dominating cycles and paths in graphs with large neighborhood unions
Authors: Broersma H. J. , Veldman H. J.
Published: June 2007

Let G be a graph of order n and define NC(G) = min{|N(u) ∪ N(v)| |uv ∉ E(G)}. A cycle C of G is called a dominating cycle or D‐cycle if V(G) ‐ V(C) is an independent set. A D‐path is defined analogously. The following result is proved: if G is 2‐connected and contains a D‐cycle, then G contains a D‐cycle of length at least min{n, 2NC(G)} unless G is the Petersen graph. By combining this result with a known sufficient condition for the existence of a D‐cycle, a common generalization of Ore's Theorem and several recent “neighborhood union results” is obtained. An analogous result on long D‐paths is also established.
On a conjecture of wang and williams
Authors: Mahadev N. V. R. , Peled Uri N.
Published: June 2007

Wang and Williams defined a threshold assignment for a graph G as an assignment of a non‐negative weight to each vertex and edge of G, and a threshold t, such that a set S of vertices is stable if and only if the total weight of the subgraph induced by S does not exceed t ‐ 1. This is always possible with zero vertex‐weights, unit edge‐weights, and t = 1. By definition, a threshold graph is a graph having a threshold assignment with zero edge‐weights. The threshold weight of G is the minimum total edgeweight of a threshold assignment of G. A graph G = (V,E) is called heavy if its threshold weight is |E|. A clique C of G is called big if |E(C)| > |E(G ‐ C)|. Wang and Williams showed that graphs with a big clique are not heavy, and conjectured the converse. They verified the conjecture for triangle‐free graphs. We disprove the conjecture in general, but prove it for perfect graphs.
Updating the hamiltonian problem—A survey
Authors: Gould Ronald J.
Published: June 2007

This is intended as a survey article covering recent developments in the area of hamiltonian graphs, that is, graphs containing a spanning cycle. This article also contains some material on related topics such as traceable, hamiltonian‐connected and pancyclic graphs and digraphs, as well as an extensive bibliography of papers in the area.
How to deal with unlabeled random graphs
Authors: Łuczak Tomasz
Published: June 2007

Let U(n,M) be a graph chosen at random from the family of all unlabeled graphs with n vertices and M edges. In the paper we study the asymptotic behavior of U(n,M) when n → ∞. In particular, we show how properties of U(n,M) could be derived from analogous properties of a labeled random graph.
Smallest regular graphs with prescribed odd girth
Authors: Zhang Guo‐Hui
Published: June 2007

The odd girth of a graph G gives the length of a shortest odd cycle in G. Let f(k,g) denote the smallest n such that there exists a k‐regular graph of order n and odd girth g. The exact values of f(k,g) are determined if one of the following holds:

k > 2g −5 and k is a prime number,

k > (2⌊(g + 1)/4⌋ −1)2, and

k is a perfect square.
Multiplicativity. Part II. Nonmultiplicative digraphs and characterization of oriented paths
Authors: Zhou Huishan
Published: June 2007

We shall prove that an oriented path is multiplicative if and only if it is homomorphically equivalent to a directed path. We shall also obtain some classes of digraphs that are nonmultiplicative.
Almost resolvable Pk‐decompositions of complete graphs
Authors: Yu Min‐Li
Published: June 2007

An almost Pk‐factor of G is a Pk‐factor of G ‐ {v} for some vertex v. An almost resolvable Pk‐decomposition of λKn is a partition of the edges of λKn into almost Pk‐factors. We prove that necessary and sufficient conditions for the existence of an almost resolvable Pk‐decomposition of λKn are n ≡ 1 (mod k) and λnk/2 ≡ 0 (mod k −1).
Vertex‐transitive graphs and vertex‐transitive maps
Authors: Babai László
Published: June 2007

We consider vertex‐transitive graphs embeddable on a fixed surface. We prove that all but a finite number of them admit embeddings as vertex‐transitive maps on surfaces of nonnegative Euler characteristic (sphere, projective plane, torus, or Klein bottle). It follows that with the exception of the cycles and a finite number of additional graphs, they are factor graphs of semiregular plane tilings. The results generalize previous work on the genus of minimal Cayley graphs by V. Proulx and T. W. Tucker and were obtained independently by C. Thomassen, with significant differences in the methods used. Our method is based on an excursion into the infinite. The local structure of our finite graphs is studied via a pointwise limit construction, and the infinite vertex‐transitive graphs obtained as such limits are classified by their connectivity and the number of ends. In two appendices, we derive a combinatorial version of Hurwitz's Theorem, and classify the vertex‐transitive maps on the Klein bottle.
Cycles intersecting a prescribed vertex set
Authors: Kaneko Atsushi , Saito Akira
Published: June 2007

A graph is said to have property P(k,l)(k ⩾ l) if for any X ∈ (Gk) there exists a cycle such that |X ∩ V(C)| = l. Obviously an n‐connected graph (n ⩾ 2) satisfies P(n,n). In this paper, we study parameters k and l such that every n‐connected graph satisfies P(k,l). We show that for r = 1 or 2 every n‐connected graph satisfies P(n + r,n). For r = 3, there are infinitely many 3‐connected graphs that do not satisfy P(6,3). However, if n ⩾ max{3,(2r −1)(r + 1)}, then every n‐connected graph satisfies P(n + r,n).
Directed hamiltonian graphs
Authors: Manoussakis Yannis
Published: June 2007

We give a new condition involving degrees sufficient for a digraph to be hamiltonian.
On replete graphs
Authors: Frick M.
Published: June 2007

A graph G is k‐clique replete if G has clique number k and every elementary homomorphism of G has clique number greater than k. Results on the order of k‐clique replete graphs are presented, and bounds for the minimum degree and the maximum degree of such graphs are discussed.
The maximum valency of regular graphs with given order and odd girth
Authors: Zhang Guo‐Hui
Published: June 2007

The odd girth of a graph G is the length of a shortest odd cycle in G. Let d(n, g) denote the largest k such that there exists a k‐regular graph of order n and odd girth g. It is shown that dn, g ≥ 2|n/g≥ if n ≥ 2g. As a consequence, we prove a conjecture of Pullman and Wormald, which says that there exists a 2j‐regular graph of order n and odd girth g if and only if n ≥ gj, where g ≥ 5 is odd and j ≥ 2. A different variation of the problem is also discussed.
The connectivity of the basis graph of a branching greedoid
Authors: Broersma H. J. , Xueliang Li
Published: June 2007

A result of Korte and Lovász states that the basis graph of every 2‐ connected greedoid is connected. We prove that the basis graph of every 3‐connected branching greedoid is (δ ‐‐ 1)‐connected, where δ is the minimum in‐degree (disregarding the root) of the underlying rooted directed (multi) graph. We also give examples showing that this results is (in some sense) best possible.
2‐neighborhoods and hamiltonian conditions
Authors: Ronghua Shi
Published: June 2007

In terms of local properties of 2‐neighborhoods (sets of vertices at distance 2 from a vertex or a subgraph), new sufficient conditions for a graph to be hamiltonian are obtained. In particular, results of Fan and Chavátal and Erdös are generalized. The new results also apply to graphs with larger diameter.
Subgraphs of a hypercube containing no small even cycles
Authors: Chung Fan R. K.
Published: June 2007

We investigate several Ramsey‐Turán type problems for subgraphs of a hypercube. We obtain upper and lower bounds for the maximum number of edges in a subgraph of a hypercube containing no four‐cycles or more generally, no 2k‐cycles C2k. These extermal results imply, for example, the following Ramsey theorems for hypercubes: A hypercube can always be edge‐partitioned into four subgraphs, each of which contains no six‐cycle. However, for any integer t, if the n‐cube is edge‐partitioned into t sub‐graphs, then one of the subgraphs must contain an edight‐cycle, provided only than n is sufficiently large (depending only on t).
s‐strongly perfect cartesian product of graphs
Authors: Olaru Elefterie , Mǎndrescu Eugen
Published: June 2007

The study of perfectness, via the strong perfect graph conjecture, has given rise to numerous investigations concerning the structure of many particular classes of perfect graphs. In “Perfect Product Graphs” (Discrete Mathematics, Vol. 20, 1977, pp. 177‐‐186), G. Ravindra and K. R. Parthasarathy tried, but unfortunately without success, to characterize the perfectness of the cartesian product of graphs (see also MR No. 58‐‐10567, 1979). In this paper we completely characterize the graphs that are both nontrivial cartesian products and s‐strongly perfect.
Centroids and medians of finite metric spaces
Authors: Bandelt Hans‐ JÜRgen
Published: June 2007

The median of a weighted finite metric space consists of the points minimizing the total weighted distance to the points of the space. The centroid is formed by the points p satisfying the following minimax condition: the maximal weight of a geodesically convex set not containing a point X attains its minimum at p. It is well known that in a tree network the centroid and the median coincide for every distribution of weights. The metric spaces for which the latter property is characteristic are determined in this paper. These spaces are obtained from three classess of graphs: median graphs, joins of complete graphs with edgeless graphs, and joins of two‐vertex edgeless graphs.
On the irregularity strength of the m × n grid
Authors: Dinitz Jeffrey H. , Garnick David K. , Gyárfás Andras
Published: June 2007

Given a graph G with weighting w: E(G) ← Z+, the Strength of G(w) is the maximum weight on any edge. The sum of a vertex in G(w) is the sum of the weights of all its incident edges. The network G(w) is irregular if the vertex sums are distinct. The irregularity strength of G is the minimum strength of the graph under all irregular weightings. In this paper we determine the irregularity strength of the m × n grid for certain m and n. In particular, for every positive integer d we find the irregularity strength for all but a finite number of m × n grids where n ‐ m = d. In addition, we present a general lower bound for the irregularity strength of graphs. © 1992 John Wiley & Sons, Inc.
Induced matchings in cubic graphs
Authors: Horák Peter , Qing He , Trotter William T.
Published: June 2007

In this paper, we show that the edge set of a cubic graph can always be partitioned into 10 subsets, each of which induces a matching in the graph. This result is a special case of a general conjecture made by Erdös and Nešetřil: For each d ≥ 3, the edge set of a graph of maximum degree d can always be partitioned into [5d2/4] subsets each of which induces a matching. © 1993 John Wiley & Sons, Inc.