bluuebunny/crossref_metadata_2025 huggingface dataset:
Desaturase mutants reveal that membrane rigidification acts as a cold perception mechanism upstream of the diacylglycerol kinase pathway in Arabidopsis cells
Authors: Vaultier Marie-Noëlle , Cantrel Catherine , Vergnolle Chantal , Justin Anne-Marie , Demandre Chantal , Benhassaine-Kesri Ghouziel , Çiçek Dominique , Zachowski Alain , Ruelland Eric
Published: July 2006

Membrane rigidification could be the first step of cold perception in poikilotherms. We have investigated its implication in diacylglycerol kinase (DAGK) activation by cold stress in suspension cells from Arabidopsis mutants altered in desaturase activities. By lateral diffusion assay, we showed that plasma membrane rigidification with temperature decrease was steeper in cells deficient in oleate desaturase than in wild type cells and in cells overexpressing linoleate desaturase. The threshold for the activation of the DAGK pathway in each type of cells correlated with this order of rigidification rate, suggesting that cold induced‐membrane rigidification is upstream of DAGK pathway activation.
Hyper‐thermostability of CutA1 protein, with a denaturation temperature of nearly 150 °C
Authors: Tanaka Tomoyuki , Sawano Masahide , Ogasahara Kyoko , Sakaguchi Yasushi , Bagautdinov Bagautdin , Katoh Etsuko , Kuroishi Chizu , Shinkai Akeo , Yokoyama Shigeyuki , Yutani Katsuhide
Published: July 2006

We found that the CutA1 protein, from Pyrococcus horikoshii (PhCutA1), has an extremely high denaturation temperature (T
d) of nearly 150 °C, which exceeds the highest record determined by DSC by about 30 °C. To elucidate the mechanism of the ultra‐high stability of PhCutA1, we analyzed the crystal structures of CutA1 proteins from three different sources, P. horikoshii, Thermus thermophilus, and Escherichia coli, with different growth temperatures (98, 75, and 37 °C). This analysis revealed that the remarkably increased number of ion pairs in the monomeric structure contributes to the stabilization of the trimeric structure and plays an important role in enhancing the T
d, up to 150 °C, for PhCutA1.
Very low levels of cholecystokinin octapeptide activate Na‐pump in the cerebral cortex of CCK2receptor‐deficient mice
Authors: Roots Kristiina , Kairane Czeslava , Salum Tiit , Kõks Sulev , Karelson Ello , Vasar Eero , Zilmer Mihkel
Published: July 2006

This study provides the first evidence that CCK‐8 (0.01 pM to 0.1 mM) stimulates Na,K‐ATPase in the cortical membranes of wild‐type and CCK2receptor‐deficient mice. In each genotype, the maximal stimulation was about 40%. Homozygous mice revealed substantially lower EC50(4 pM) than heterozygous (37 pM) or wild‐type animals (682 pM). In homozygous CCK2receptor‐deficient mice, the expression of CCK1receptor gene was 5‐fold higher than in wild‐type animals. CCK1receptor antagonist devazepide counteracted effect of CCK‐8 in all three genotypes, whereas CCK2receptor antagonist L‐365, 260 showed significant antagonism in wild‐type and heterozygous mice. The cooperativity of Na,K‐ATPase for Na+, but not for K+, was lost in homozygous mice. Altogether, very low concentrations of CCK‐8 via CCK1and CCK2receptors stimulate Na,K‐ATPase in the cerebral cortex. CCK2receptor‐deficiency leads to the altered functionality of Na,K‐ATPase that might be compensated by CCK1receptor mediated influence of CCK (and its agonists) on the enzyme.
Women's access to health care: The legal framework
Authors: Cook R.J. , Ngwena C.G.
Published: July 2006

The Millennium Development Goals set ambitious targets for women's health, including reductions in maternal and child mortality and combating the spread of HIV/AIDS. The law, which historically has often obstructed women's access to the health care they require, has a dynamic potential to ensure women's access that is being progressively realized. This paper identifies three legal principles that are key to advancing women's reproductive and sexual health. First, law should require that care be evidence‐based, reflecting medical and social science rather than, for instance, religious ideology or morality. Second, legal guidance should be clear and transparent, so that service providers and patients know their responsibilities and entitlements without litigation to resolve uncertainties. Third, law should provide applicable measures to ensure fairness in women's access to services, both general services and those only women require. Legal developments are addressed that illustrate how law can advance women's equality, and social justice.
Non-Subungual Melanomas of the Hand
Authors: QUINN M. J. , WIKRAMANAYAKE R. , THOMPSON J. F. , McCARTHY W. H.
Published: July 2006

The non-subungual area of the hand is a rare anatomical site for malignant melanoma, lesions in this site comprising only 0.37% of 8,584 cutaneous melanomas in the Sydney Melanoma Unit database. This is approximately the same frequency of melanoma as is found on the subungual region of the hand, which represents a much smaller surface area. Not only is the sub-site distribution on the hand unusual but in addition the histogenetic types of melanoma found on the dorsum of the hand are not those commonly encountered on sun exposed skin. In this study, comparison is made between melanomas occurring on the non-subungual areas of the hand and those on the foot, an anatomically similar surface area. Comparison is also made between melanomas arising on the dorsal non-subungual surface of the hand and those on the face, a region with an equivalent surface area and similar sun exposure. The results of surgical treatment of 31 melanomas of the non-subungual region of the hand are reviewed.
Radical Microarteriolysis in the Treatment of Vasospastic Disorders of the Hand, Especially Scleroderma
Authors: O’BRIEN BMcC , KUMAR P. A. V. , MELLOW C. G. , OLIVER T. V.
Published: July 2006

Arterial spasm due to exaggerated sympathetic response is an important mechanism for Raynaud’s phenomenon in scleroderma associated often with periadventitial scarring. The results of cervical sympathectomy have been unsatisfactory in the upper limb because of additional sympathetic pathways. Flatt therefore devised a distal sympathectomy by stripping the vessels of their adventitia over a short length of artery. The results of this operation were found by Wilgis in a large series to be poor in patients with scleroderma. A radical distal microarteriolysis including adventitia and surrounding scar is described and the results in 13 patients, 11 with scleroderma, are reported. Minimum follow-up is one year. All patients had relief from pain at rest and healing of painful ulceration. Mild recurrence of small ulcers was seen in only four patients.
Silastic Replacement of the Trapezium
Authors: FREEMAN G. R. , HONNER R.
Published: July 2006

A retrospective study has been made of the long-term results of silastic replacement of the trapezium, including functional, clinical and radiological assessment of 43 hands, one to 13 years postoperatively. The results showed good function and relief of pain in 88% of hands. Radiolucent bone lesions, presumably due to silastic particle reaction, occurred in 53% of hands, but their presence did not correlate well with symptoms. Four patients (9%) developed significant synovitis which was improved by removal of the prosthesis. In this series, clinical silastic synovitis occurred in the first four years, and its incidence did not increase with further follow-up to 13 years.
Dating metamorphism and tectonic juxtaposition on Andros Island (Cyclades, Greece): results of a Rb–Sr study
Authors: BRÖCKER M. , FRANZ L.
Published: July 2006

This paper reports new geochronological data from the island of Andros, one of the less-studied islands of the Cycladic blueschist belt in the central Aegean Sea. On Andros, two tectonic units can be distinguished, the Makrotantalon unit and the Lower unit, which are separated by a low-angle normal fault, related to large-scale regional extension. Mineral assemblages indicate greenschist-facies P–T conditions for the last metamorphic overprint of both units. In contrast to the structurally lower unit, unambiguous indications for an earlier high-pressure stage were not recognized in rocks collected above the tectonic contact. Owing to a polyphase metamorphic evolution and incomplete resetting of the Rb–Sr isotope system during overprinting, phengite geochronology indicates a wide range in dates between c. 104 and 21 Ma for the Makrotantalon unit, as observed in rocks of similar structural position elsewhere in the Cyclades. The new Rb–Sr data support the interpretation, but are not conclusive evidence, that tectonic slices within the hanging wall were affected by two periods of Cretaceous metamorphism (c. 100–90 Ma and c. 80–70 Ma) and a Miocene event (c. 21 Ma). Tectonic juxtaposition was accomplished around c. 21 Ma. The Lower unit is correlative with the Cycladic high-pressure occurrences. Rb–Sr phengite dating yielded the same range in ages as determined elsewhere in the region for white mica of high-pressure rocks (c. 50–40 Ma) and their overprinted, greenschist-facies derivatives (c. 23–21 Ma). An age gradient towards the tectonic contact with the overlying Makrotantalon unit is not developed. The new results fit well into the previously established chronological framework for the larger study area. Indications for regional differences in the timing of the HP stage and/or the greenschist-facies overprint have not yet been found.
L-lactate dehydrogenase and N-acetyl-β-D-glucosaminidase activities in bovine milk as indicators of non-specific mastitis
Authors: Chagunda Mizeck GG , Larsen Torben , Bjerring Martin , Ingvartsen Klaus L
Published: July 2006

Systematic factors affecting the activities of L-lactate dehydrogenase (LDH) and N-acetyl-β-D-glucosaminidase (NAGase) and somatic cell count (SCC), the association between the activities of LDH and NAGase and SCC with respect to udder health status, and the ability of LDH and NAGase to classify cows in udder health categories for early detection of mastitis were studied. A dataset of records from 74 Danish Holstein, 76 Danish Red and 47 Jersey cows on one research farm was used. Cows were grouped into healthy and clinically mastitic. A healthy cow was defined as having no veterinary treatment and SCC<100000 cells/ml. A clinically infected cow was one receiving veterinary treatment after showing clinical signs of mastitis and SCC >800000 cells/ml. Breed, month of production, and days in milk significantly influenced (P<0·001) LDH activity, NAGase activity and SCC in both healthy and clinically mastitic cows. In healthy cows, LDH activity, NAGase activity and SCC started at a high level immediately after calving and decreased to low levels approximately 30–40 d post partum. All the three parameters increased due to clinical mastitis. NAGase activity had numerically higher variation in healthy cows than in clinically mastitic cows (CV=56·2% v. CV=53·5%). The relationship between LDH activity and SCC was stronger in milk from clinically mastitic than from healthy cows (r=0·76 v. r=0·48 and r=0·67 v. r=0·44 for correlation of observed values and residuals, respectively). LDH activity had higher sensitivity than NAGase activity (73–95% v. 35–77%) while specificities were in a similar range (92–99%). Further, sensitivities for LDH activity were more robust to changes in the threshold value than those for NAGase activity. Opportunities for automated, in-line real-time mastitis detection are discussed.
Effects of the oral administration of the products derived from milk fermentation by kefir microflora on immune stimulation
Authors: Vinderola Gabriel , Perdigón Gabriela , Duarte Jairo , Farnworth Edward , Matar Chantal
Published: July 2006

Nutritional status has a major impact on the immune system. Probiotic effects ascribed to fermented dairy products arise not only from whole microorganisms but also from metabolites (peptides, exopolysaccharides) produced during the fermentation. We recently demonstrated the immunomodulating capacity of kefir in a murine model. We now aimed at studying the immunomodulating capacity in vivo of the products derived from milk fermentation by kefir microflora (PMFKM) on the gut. BALB/c mice received the PMFKM for 2, 5 or 7 consecutive days. IgA+ and IgG+ cells were determined on histological slices of the small and large intestine. IL-4, IL-6, IL-10, IL-12, IFNγ and TNFα were determined in the gut, intestinal fluid and blood serum. IL-6 was also determined in the supernatant of a primary culture of small intestine epithelial cells challenged with PMFKM. PMFKM up-regulated IL-6 secretion, necessary for B-cell terminal differentiation to IgA secreting cells in the gut lamina propria. There was an increase in the number of IgA+ cells in the small and large intestine. The increase in the number of IgA+ cells was accompanied by an increase in the number of IL-4+, IL-10+ and IL-6+ cells in the small intestine. Effects of PMFKM in the large intestine were less widely apparent than the ones observed at the small intestine lamina propria. All cytokines that increased in the small intestine lamina propria, also did so in blood serum, reflecting here the immunostimulation achieved in the gut mucosa. We observed that the PMFKM induced a mucosal response and it was able to up and down regulate it for protective immunity, maintaining the intestinal homeostasis, enhancing the IgA production at both the small and large intestine level. The opportunity exists then to manipulate the constituents of the lumen of the intestine through dietary means, thereby enhancing the health status of the host.
Welfare effects of reduced milk production associated with Johne's disease on Johne's-positive versus Johne's-negative dairy operations
Authors: Losinger Willard C
Published: July 2006

An examination of the economic impacts of reduced milk production associated with Johne's disease on Johne's-positive and Johne's-negative dairy operations indicated that, if Johne's disease had not existed in US dairy cows in 1996, then the economic surplus of Johne's-negative operations would have been $600 million±$530 million lower, while the economic surplus of Johne's-positive operations would have been higher by $28 million±$79 million, which was not significantly different from zero. The data available for projecting changes in surplus were not sufficiently precise to allow an exact statement on whether Johne's-positive operations would have been better or worse off economically, in terms of the value received for producing more milk if they had not been affected by Johne's disease. The changes in producer surplus, based upon eliminating specific epidemiological risk factors for Johne's disease, were disaggregated between Johne's-positive dairy operations exposed to the risk factor and all other US dairy operations. Eliminating the risk factor of having any cows not born on the operation would have had a significant positive effect on the economic surplus of Johne's-positive operations that had any cows not born on the operation.
Weakly dissipative ion acoustic solitary waves in a dusty plasma: roles of dust charge variation, ion loss and ionization
Authors: GHOSH SAMIRAN
Published: July 2006

The nonlinear propagation characteristics of dust ion acoustic waves in the presence of weak dissipations arising due to the low rates (compared to the ion oscillation frequency) of ionization, ion loss and dust charging are investigated. It is found that the ion acoustic solitary wave in such a dusty plasma is weakly dissipative in nature and is governed by a modified form of the Korteweg–de Vries equation. The analytical solution reveals that the ionization has a destabilizing effect, whereas ion loss and dust charge variation play a stabilizing role to control the ionization instability.
High prevalence of metallo-β-lactamase-mediated resistance challenging antimicrobial therapy against Pseudomonas aeruginosa in a Brazilian teaching hospital
Authors: ZAVASCKI A. P. , GOLDANI L. Z. , GONÇALVES A. L. S. , MARTINS A. F. , BARTH A. L.
Published: July 2006

The prevalence of metallo-β-lactamase (MBL) production among Pseudomonas aeruginosa nosocomial isolates from a Brazilian teaching hospital was determined. A total of 512 P. aeruginosa isolates were recovered from 245 patients during a 10-month period. Ninety-four (38·4%, 95% CI 32·2–44·8%) isolates were MBL producers. Most resistance to β-lactams was mediated by MBL. Forty-one (16·7%) were resistant to all drugs except polymyxin B and 33 (80·5%) of these were MBL producers. Clonal dissemination, documented by DNA macrorestriction, played a major role for the spread of MBL isolates. The blaSPM-1 gene was demonstrated by PCR in 14 randomly selected MBL isolates. The extremely high prevalence of MBL production found challenges the choice of therapeutics for P. aeruginosa, and measures to control horizontal dissemination of MBL producers are urgently required.
Editorial
Authors: Salkovskis Paul
Published: July 2006

Our field continues to grow and develop rapidly, not only in terms of the theory and research that underpins our clinical work but also in the breadth and richness of the clinical skills that allow us to apply this knowledge in ways that empower those who seek help from us. Recent submissions to this journal are testament to the growing technology evolving around issues such as training and supervision. The pace of development of the basic and applied science that underpins the work of CBT practitioners is unparalleled. The BABCP and this journal have contributed to and influenced these developments; we need to continue to do so.
Terdiurnal tidelike variability in sporadic E layers
Authors: Haldoupis Christos , Pancheva Dora
Published: July 2006

Time series analysis was performed on a large database of ionosonde recordings taken over 12 years, for the 6‐month period from the beginning of May to the end of October when sporadic E layer occurrence is frequent. The results show that in addition to the well known 24‐ and 12‐hour tidal variations, there is also a weaker but regular 8‐hour periodicity in midlatitude sporadic E layers (Es). Statistically, this terdiurnal periodicity is significant and occurs in both the sporadic E layer critical frequency (foEs) and the layer virtual height (h′Es), becoming strongest around summer solstice and later in October after a minimum in September. At times a weak 6‐hour periodicity can also be present in Es but its effects are much less significant than those of the 8‐hour oscillation. The 8‐hour periodicity in Es is attributed to the terdiurnal tide, presumably acting through its vertical wind shear forcing of the metallic ions in the lower thermosphere. The relation to the terdiurnal tide was inferred from simultaneous ionosonde recordings from three widely spaced stations in the same midlatitude zone, showing the 8‐hour oscillation to be present simultaneously in all ionosonde stations and have phases which are consistent with a westward propagating terdiurnal wave of zonal wave number 3. The present study establishes the regular occurrence of a terdiurnal tidelike oscillation in Es which needs to be incorporated into the physics and modeling of sporadic E layer formation and dynamics.
Empirical temperature‐based estimates of variability in the oceanic uptake of CO2 over the past 2 decades
Authors: Park Geun‐Ha , Lee Kitack , Wanninkhof Rik , Feely Richard A.
Published: July 2006

We infer the year‐to‐year variability of net global air‐sea CO2 fluxes from observed interannual changes in wind speed and estimated differences in CO2 partial pressure between surface seawater (pCO2SW) and the overlying atmosphere. Changes in pCO2SW are estimated from changes in sea surface temperature via seasonal algorithms that relate pCO2SW to sea surface temperature. Our diagnostic model yields an interannual variability of ±0.18 petagrams (1σ, Pg = 1015 grams) of carbon per year for the period 1982–2001. El Niño Southern Oscillation–induced changes in the equatorial efflux contribute approximately 70% of the diagnostic modeled global variability. Regional flux anomalies for areas outside the equatorial Pacific are found to neither systematically reinforce nor counteract each other during times of transition from El Niño years to normal years. The interannual variability of ±0.18 Pg C yr−1 obtained in the present work is at the low end of previous estimates that falls in the range of ±0.2 to ±0.5 Pg C yr−1. Of the previous estimates, lower values are generally estimated from global ocean circulation–biogeochemical models, while higher values are derived from atmospheric inversion models constrained by atmospheric CO2 observations. Comparisons of our modeled results with two time series data sets and equatorial Pacific data suggest that our diagnostic model is not able to capture the full range of pCO2SW variations; this is probably due to the inability of the empirical model to fully account for changes in surface pCO2SW related to ocean biological and physical processes. The small interannual variability in our modeled fluxes suggests that observed year‐to‐year variations in the rate of atmospheric CO2 increase are primarily caused by changes in the rate of CO2 uptake by the land biosphere.
Recent rapid warming trend revealed from the isotopic record in Muztagata ice core, eastern Pamirs
Authors: Tian Lide , Yao Tandong , Li Zhen , MacClune Kenneth , Wu Guangjian , Xu Baiqing , Li Yuefang , Lu Anxian , Shen Yongping
Published: July 2006

Many have made efforts to clarify the climatic significance of stable isotopic variations in ice cores around central Asia through the study of stable isotopes in present‐day precipitation. A new shallow ice core from Muztagata, in the eastern Pamirs, allows for a detailed comparison of annual δ18O variation with local meteorological data as well as with global air temperature variations. On the basis of a comparison of seasonal fluctuations of δ18O in the local precipitation, the 41.6‐m ice core drilled at 7010 m provides a record of about one‐half century. The annual fluctuations of δ18O in this ice core are in good agreement (correlation coefficient of 0.67) with the annual air temperature changes at the nearby meteorological station Taxkorgen, indicating that the isotopic record from this ice core is a reliable temperature trend indicator. The most important discovery from the δ18O variation of this ice core is a rapid warming trend in the 1990s, which is consistent with a general global warming trend over this time period. This recent rapid warming at higher elevations in this area has led to the quick retreat of alpine glaciers.
High‐resolution airborne profiles of CH4, O3, and water vapor near tropical Central America in late January to early February 2004
Authors: Richard E. C. , Tuck A. F. , Aikin K. C. , Kelly K. K. , Herman R. L. , Troy R. F. , Hovde S. J. , Rosenlof K. H. , Thompson T. L. , Ray E. A.
Published: July 2006

High‐resolution (1 Hz at true airspeeds near 200 m s−1) observations of methane, ozone, water vapor, and temperature taken between the surface and 18 km from the WB57F aircraft near San José, Costa Rica (10°N, 84°W), are used to examine processes influencing the maintenance of these profiles. There was a clearly defined thermal tropopause on each of the eight profiles, accompanied by structure on methane‐ozone scatterplots on the five profiles having methane observations. There was a well‐defined decrease in methane mixing ratio between approximately 12 and 15 km in each of these five profiles, 2–5 km beneath the thermal tropopause, correlated with sharp changes in water vapor and equivalent potential temperature. The methane observations are interpreted as meaning that air is recirculated between the lower stratosphere and the upper tropical troposphere. At the point on each vertical profile where the water vapor had its minimum value, the air was never saturated or apparently supersaturated, although apparent supersaturation with respect to ice was observed in vertically extensive, near‐adiabatic layers with tops some 200–300 m below the water vapor minimum on all profiles. One of the profiles also exhibited apparent supersaturation above its water vapor minimum, near 18 km. We examine the decrease in water vapor to minimal values as a four‐stage process in which its mixing ratio was lowered from ∼10 to ∼3 ppmv, consider the role of solar and thermal evaporation of the smaller ice particles in the final stage of the dehydration process, and correlate features separating near‐adiabatic layers above 150 hPa pressure altitude with local sea surface temperatures.
Direct gas injection into saturated glass beads: Transition from incoherent to coherent gas flow pattern
Authors: Geistlinger Helmut , Krauss Gunnar , Lazik Detlef , Luckner Ludwig
Published: July 2006

The transition from incoherent to coherent buoyancy‐driven gas flow is investigated in two‐dimensional tanks filled with glass beads using a high‐resolution optical‐gravimetrical setup. Both a grain‐size (dk)‐ and flow rate (Q)‐dependent transition are observed in the gas flow pattern. Standard quasistatic criteria do not explain the experimental results, since they do not take into account the competition between stabilizing friction forces and destabilizing capillary and gravitational forces. Conceptualizing the steady state tortuous gas flow as core‐annulus flow and applying Hagen‐Poiseuille flow for a straight capillary, we propose a flow rate and grain‐size‐dependent stability criterion that accounts for the experimental results and is used to classify the experiments in a dk‐Q diagram.
Influence of marine denitrification on atmospheric N2O variability during the Holocene
Authors: Agnihotri Rajesh , Altabet Mark A. , Herbert T. D.
Published: July 2006

Oceanic denitrification centers are thought to be important marine sources for atmospheric N2O. To consider Holocene variability in this source, we reconstruct the Holocene paleo‐denitrification history of the Peru margin, a major marine denitrification center, using high‐resolution sedimentary δ15N data. This record along with a contemporaneous one from the western Arabian Sea (Altabet et al., 2002) shows similarities with the recently available high‐resolution atmospheric N2O record (Flückiger et al., 2002). While the role of terrestrial processes in the observed N2O changes remains uncertain, these results suggest that variability in marine denitrification in major upwelling centers such as the Peru margin and the Arabian Sea contributed significantly to atmospheric N2O evolution during the Holocene.
Modifications of a land surface scheme for improved simulation of ground freeze‐thaw in northern environments
Authors: Yi Shuhua , Arain M. Altaf , Woo Ming‐Ko
Published: July 2006

Freezing and thawing front (FTF) depths have implications for surface and subsurface exchanges of energy and water, vegetation growth and organic matter decomposition. Long‐term changes in FTF depths are an important indicator of climate change. The FTF is seldom represented explicitly in land surface schemes, but the 0°C isotherm is used as a surrogate for the front. However, when multiple FTFs occur within a soil column or when soil temperature hovers around the freezing point in the spring, the simulated 0°C isotherm exhibits large fluctuations though in reality, the fronts develop rather smoothly. To explicitly simulate the FTF depths, this study couples a Two‐Direction Stefan Algorithm (TDSA) in the Community Land Model 3 (CLM3). Several modifications are also introduced to adapt the CLM3 to the northern region, including the addition of a peat cover to the soil column, retention of a minimum unfrozen water content in the frozen soil, and implementation of canopy heat storage. The modified scheme was tested using field data from a boreal forest site. The TDSA enables the simulated FTF to be defined properly. Sensitivity tests demonstrate that the modified scheme (addition of a peat cover, unfrozen water and canopy heat storage) greatly improves the match between the simulated fronts and the 0°C isotherm derived from measured soil temperatures. These modifications and the coupling of the TDSA are applicable to other lands surface schemes for the simulation of ground frost in the cold regions.
Laboratory observation of oligomers in the aerosol from isoprene/NOx photooxidation
Authors: Dommen J. , Metzger A. , Duplissy J. , Kalberer M. , Alfarra M. R. , Gascho A. , Weingartner E. , Prevot A. S. H. , Verheggen B. , Baltensperger U.
Published: July 2006

Compounds assigned to be oxidation products of isoprene (2‐methyl‐1,3‐butadiene) have recently been observed in ambient aerosols, suggesting that isoprene might play an important role in secondary organic aerosol (SOA) formation due to its large global source strength. SOA yields from photooxidation of isoprene and NOx in a chamber agree fairly well with previous data. Matrix assisted laser desorption/ionization mass spectrometry showed the formation of high molecular weight compounds over the course of 15‐hour experiments. Concurrently, the volatility of the SOA decreased markedly as observed by a tandem differential mobility analyzer. The volume fraction remaining of SOA at 150°C increased steadily from 5 to 25% during the same experiments. These observations are attributed to oligomerization reactions occurring in the aerosol phase. Under dry conditions a lower volatility was observed.
Far‐reaching Hawaiian Lee Countercurrent driven by wind‐stress curl induced by warm SST band along the current
Authors: Sasaki Hideharu , Nonaka Masami
Published: July 2006

Two eddy‐resolving ocean simulations are carried out to study local air‐sea interaction associated with the Hawaiian Lee Countercurrent (HLCC), one forced by the QuikSCAT satellite wind field (QSCAT run) and the other by the NCEP/NCAR reanalysis (NCEP run). The simulated HLCC in the QSCAT run extends west‐southwestward from the Hawaiian Islands much farther than that in the NCEP run. We attribute this difference to difference in the wind fields. In the QSCAT wind field, there exist band‐like structures of positive and negative wind stress curls induced by warm sea surface temperature band associated with the HLCC; however, these features are not apparent in the reanalysis wind field. The QSCAT run provides a good example of local two‐way air‐sea interactions in association with the HLCC. Furthermore, interannual variations are suggested in both the simulated HLCC and wind fields over the HLCC.
Impact of 3‐D Earth structure on Fennoscandian glacial isostatic adjustment: Implications for space‐geodetic estimates of present‐day crustal deformations
Authors: Whitehouse Pippa , Latychev Konstantin , Milne Glenn A. , Mitrovica Jerry X. , Kendall Roblyn
Published: July 2006

The importance of including lateral Earth structure in the analysis of Fennoscandian glacial isostatic adjustment (GIA) is investigated using a finite volume numerical formulation. Comparing output from radially‐varying 1‐D Earth models and models which account for the presence of plate boundaries, lateral variations in lithospheric thickness and viscosity heterogeneities in the upper and lower mantle, we find that perturbations to present‐day rates of surface deformation due to the inclusion of 3‐D Earth structure significantly exceed current observational uncertainties. Predicted residuals between 1‐D and 3‐D Earth models may be improved with the use of a 1‐D model which approximates the local depth‐dependent mean of the 3‐D model. However, the remaining misfit is still large enough to significantly bias inferences of Earth structure and ice history. We conclude that lateral variations at both global and regional scales must be accounted for when interpreting GPS observations from Fennoscandia.
Molecular dissection of arginyltransferases guided by similarity to bacterial peptidoglycan synthases
Authors: Rai Reena , Mushegian Arcady , Makarova Kira , Kashina Anna
Published: July 2006

Post‐translational protein arginylation is essential for cardiovascular development and angiogenesis in mice and is mediated by arginyl‐transfer RNA‐protein transferases Ate1—a functionally conserved but poorly understood class of enzymes. Here, we used sequence analysis to detect the evolutionary relationship between the Ate1 family and bacterial FemABX family of aminoacyl‐tRNA‐peptide transferases, and to predict the functionally important residues in arginyltransferases, which were then used to construct a panel of mutants for further molecular dissection of mouse Ate1. Point mutations of the residues in the predicted regions of functional importance resulted in changes in enzymatic activity, including complete inactivation of mouse Ate1; other mutations altered its substrate specificity. Our results provide the first insights into the mechanisms of Ate1‐mediated arginyl transfer reaction and substrate recognition, and define a new protein superfamily called Dupli‐GNAT to reflect its origin by the duplication of the GNAT acetyltransferase domain.
Interleukin-6 Upregulates Expression of KDR and Stimulates Proliferation of Human Cerebrovascular Smooth Muscle Cells
Authors: Yao Jianhua S , Zhai Wenwu , Fan Yongfeng , Lawton Michael T , Barbaro Nicholas M , Young William L , Yang Guo-Yuan
Published: July 2006

Interleukin-6 (IL-6) may play multiple roles in angiogenesis and vascular remodeling. Our previous study showed that a promoter polymorphism (174G>C) in IL-6 is associated with brain arteriovenous malformation hemorrhage; tissue expression is related to genotype. In this study, we investigated the effects of IL-6 on human cerebral smooth muscle cells (HCSMCs) and smooth muscle cells isolated from brain arteriovenous malformation surgical specimens (AVM SMCs) and surgical controls (control HCSMCs—from structurally normal temporal lobe taken during surgical treatment of epilepsy patients). We found that IL-6 (1.1±0.27 versus 0.37±0.04 pg/mL, n=5, P<0.05) and endogenous vascular endothelial growth factor (VEGF) receptor II (kinase domain-containing receptor (KDR), 15±3 versus 1.5±3 pg/mL, n=5, P<0.05) were increased in brain AVM SMCs compared with control HCSMCs. Further research revealed that IL-6 could stimulate SMC proliferation, VEGF release, and KDR activation in control HCSMCs. It could also stimulate KDR phosphorylation in control HCSMCs, further confirming a unique role of IL-6 in the triggering of KDR. Interleukin-6 could increase matrix metalloproteinase-9 (MMP-9) secretion through activating KDR in control HCSMCs ( P<0.05 versus control). Inhibiting IL-6-induced KDR could reduce MMP-9 activity at least 50% compared with the control group ( P<0.05). Increased MMP-9 activity was accompanied by increased control HCSMC proliferation, and blocking MMP-9 activity significantly reduced IL-6-induced control HCSMC proliferation ( P<0.05). Collectively, our results show that IL-6 could activate, amplify, and maintain the angiogenic cascade in HCSMCs. A novel role of IL-6 during HCSMC proliferation is upregulating KDR expression and phosphorylation. The results may contribute to the angiogenic phenotype of human brain vascular diseases, such as brain AVM.
Cyclooxygenase-2 Does Not Contribute to Postischemic Production of Reactive Oxygen Species
Authors: Kunz Alexander , Anrather Josef , Zhou Ping , Orio Marcello , Iadecola Costantino
Published: July 2006

We sought to determine whether reactive oxygen species (ROS) derived from cyclooxygenase-2 (COX-2) are involved in ischemic brain injury. Focal cerebral ischemia was induced by transient middle cerebral artery occlusion in C57BL/6 mice. The time course of neocortical ROS production was assessed in vivo using hydroethidine as a marker. The same brain sections were used for infarct volume measurements. Transient middle cerebral artery occlusion led to a biphasic increase in ROS production with peaks 2 and 72 h after reperfusion. The COX-2 inhibitor NS398 (10 mg/kg) attenuated the production of COX-2-derived prostaglandin E2and reduced brain injury, but did not affect ROS production at 2 and 72 h. Similarly, ROS production was not reduced in COX-2-null mice. In contrast, ROS production and brain injury were reduced in mice lacking the nox2 subunit of the superoxide-producing enzyme nicotinamide adenine dinucleotide phosphate (reduced form) oxidase. The data suggest that COX-2 is not a major source of oxygen radicals after cerebral ischemia and raise the possibility that other COX-2 reaction products, including prostanoids or nonoxygen-based radicals, mediate the COX-2-dependent component of the injury.
Destabilizing missense mutations in the tumour suppressor protein p53 enhance its ubiquitination in vitro and in vivo
Authors: Shimizu Harumi , Saliba David , Wallace Maura , Finlan Lee , Langridge-Smith Patrick R. R. , Hupp Ted R.
Published: July 2006

p53 ubiquitination catalysed by MDM2 (murine double minute clone 2 oncoprotein) provides a biochemical assay to dissect stages in E3-ubiquitin-ligase-catalysed ubiquitination of a conformationally flexible protein. A mutant form of p53 (p53F270A) containing a mutation in the second MDM2-docking site in the DNA-binding domain of p53 (F270A) is susceptible to modification of long-lived and high-molecular-mass covalent adducts in vivo. Mutant F270A is hyperubiquitinated in cells as defined by immunoprecipitation and immunoblotting with an anti-ubiquitin antibody. Transfection of His-tagged ubiquitin along with p53R175H or p53F270A also results in selective hyperubiquitination in cells under conditions where wild-type p53 is refractory to covalent modification. The extent of mutant p53R175H or p53F270A unfolding in cells as defined by exposure of the DO-12 epitope correlates with the extent of hyperubiquitination, suggesting a link between substrate conformation and E3 ligase function. The p53F270A:6KR chimaeric mutant (where 6KR refers to the simultaneous mutation of lysine residues at positions 370, 372, 373, 381, 382 and 386 to arginine) maintains the high-molecular-mass covalent adducts and is modified in an MDM2-dependent manner. Using an in vitro ubiquitination system, mutant p53F270A and the p53F270A:6KR chimaeric mutant is also subject to hyperubiquitination outwith the C-terminal domain, indicating direct recognition of the mutant p53 conformation by (a) factor(s) in the cell-free ubiquitination system. These data identify an in vitro and in vivo assay with which to dissect how oligomeric protein conformational alterations are linked to substrate ubiquitination in cells. This has implications for understanding the recognition of misfolded proteins during aging and in human diseases such as cancer.
All-trans retinoic acid down-regulates human albumin gene expression through the induction of C/EBPβ-LIP
Authors: Masaki Takahiro , Matsuura Tomokazu , Ohkawa Kiyoshi , Miyamura Tatsuo , Okazaki Isao , Watanabe Tetsu , Suzuki Tetsuro
Published: July 2006

ATRA (all-trans retinoic acid), which is a major bioactive metabolite of vitamin A and a potent regulator of development and differentiation, mediates down-regulation of the human albumin gene. However, the mechanism of ATRA-mediated down-regulation is not well understood. In the present study, deletion analysis and luciferase assays demonstrate that ATRA causes a marked decrease in the activity of the albumin promoter, the region between nt −367 and −167 from the transcription start site, where C/EBP (CCAAT/enhancer-binding protein)-binding sites are tightly packed, is indispensable for ATRA-mediated down-regulation. ChIP (chromatin immunoprecipitation) assays revealed that in vivo binding of C/EBPα to the region markedly decreases upon incubation with ATRA, whereas ATRA treatment marginally increases the recruitment of C/EBPβ. We found that ATRA has the ability to differentially and directly induce expression of a truncated isoform of C/EBPβ, which is an LIP (liver-enriched transcriptional inhibitory protein) that lacks a transactivation domain, and to increase the binding activity of C/EBPβ-LIP to its response element. Overexpression of C/EBPβ-LIP negatively regulates the endogenous expression of albumin, as well as the activity of the albumin promoter induced by C/EBP transactivators such as C/EBPα and full-length C/EBPβ. In conclusion, we propose a novel model for down-regulation of the albumin gene, in which ATRA triggers an increase in the translation of C/EBPβ-LIP that antagonizes C/EBP transactivators by interacting with their binding sites in the albumin promoter.
Control and regulation of the cellular responses to cold shock: the responses in yeast and mammalian systems
Authors: Al-Fageeh Mohamed B. , Smales C. Mark
Published: July 2006

Although the cold-shock response has now been studied in a number of different organisms for several decades, it is only in the last few years that we have begun to understand the molecular mechanisms that govern adaptation to cold stress. Notably, all organisms from prokaryotes to plants and higher eukaryotes respond to cold shock in a comparatively similar manner. The general response of cells to cold stress is the elite and rapid overexpression of a small group of proteins, the so-called CSPs (cold-shock proteins). The most well characterized CSP is CspA, the major CSP expressed in Escherichia coli upon temperature downshift. More recently, a number of reports have shown that exposing yeast or mammalian cells to sub-physiological temperatures (<30 or <37 °C respectively) invokes a co-ordinated cellular response involving modulation of transcription, translation, metabolism, the cell cycle and the cell cytoskeleton. In the present review, we summarize the regulation and role of cold-shock genes and proteins in the adaptive response upon decreased temperature with particular reference to yeast and in vitro cultured mammalian cells. Finally, we present an integrated model for the co-ordinated responses required to maintain the viability and integrity of mammalian cells upon mild hypothermic cold shock.
Time sensing by NAADP receptors
Authors: Churamani Dev , Dickinson George D. , Ziegler Mathias , Patel Sandip
Published: July 2006

NAADP (nicotinic acid–adenine dinucleotide phosphate) is a newly described intracellular messenger molecule that mediates Ca2+ increases in a variety of cells. However, little is known of the mechanism whereby ligand binding regulates the target protein. We report in the present paper that NAADP receptors from sea urchin eggs undergo an unusual stabilization process that appears to be dependent upon the time during which receptors are exposed to their ligand. We demonstrate that receptors ‘tagged’ with NAADP for short periods were more readily dissociated following subsequent delipidation than those labelled for longer. Stabilization of NAADP receptors by their ligand was delayed relative to ligand association taking on the order of minutes to develop at picomolar concentrations. The stabilizing effects of NAADP did not require cytosolic factors or the continued presence of NAADP and persisted upon solubilization. NAADP receptors, however, failed to stabilize at reduced temperature. We conclude that NAADP receptors possess a simple molecular memory endowing them with the remarkable ability to detect the duration of their activation.
Differential realization of pseudo-Hermiticity: A quantum mechanical analog of Einstein’s field equation
Authors: Mostafazadeh Ali
Published: July 2006

For a given pseudo-Hermitian Hamiltonian of the standard form: H=p2∕2m+v(x), we reduce the problem of finding the most general (pseudo-)metric operator η satisfying H†=ηHη−1 to the solution of a differential equation. If the configuration space is R, this is a Klein-Gordon equation with a nonconstant mass term. We obtain a general series solution of this equation that involves a pair of arbitrary functions. These characterize the arbitrariness in the choice of η. We apply our general results to calculate η for the PT-symmetric square well, an imaginary scattering potential, and a class of imaginary delta-function potentials. For the first two systems, our method reproduces the known results in a straightforward and extremely efficient manner. For all these systems we obtain the most general η up to second-order terms in the coupling constants.
Copper electrodeposition localized in picoliter droplets using microcantilever arrays
Authors: Leïchlé T. , Nicu L. , Descamps E. , Corso B. , Mailley P. , Livache T. , Bergaud C.
Published: July 2006

A patterning tool that allows electrochemical reactions to take place inside microdroplets is introduced. This tool relies on the use of a microfabricated array of silicon cantilevers that incorporate a channel into which a gold electrode is patterned. The deposition process consists in forming picoliter droplets onto a conducting surface by a contact method and applying a voltage between the surface and the cantilevers. To demonstrate the capability of the system, arrays of 20μm diameter copper islands are electrodeposited onto gold surfaces. As expected, the copper bumps exhibit increasing heights as a result of longer deposition times.
Enhanced nitrogen diffusion induced by atomic attrition
Authors: Ochoa E. A. , Figueroa C. A. , Czerwiec T. , Alvarez F.
Published: July 2006

The nitrogen diffusion in steel is enhanced by previous atomic attrition with low energy xenon ions. The noble gas bombardment generates nanoscale texture surfaces and stress in the material. The atomic attrition increases nitrogen diffusion at lower temperatures than the ones normally used in standard processes. The stress causes binding energy shifts of the Xe 3d5∕2 electron core level. The heavy ion bombardment control of the texture and stress of the material surfaces may be applied to several plasma processes where diffusing species are involved.
Interface scattering and the tunneling magnetoresistance of Fe(001)∕MgO(001)∕Fe(001) junctions
Authors: Eames M. E. , Inkson J. C.
Published: July 2006

We present a model for the transmission coefficient which can be used to calculate the tunneling magnetoresistance for the Fe(001)∕MgO(001)∕Fe(001) system. It clarifies the role of the interface scattering into various tunneling channels, linking them to the complex band structure of the MgO. This allows a more direct relation to the interpretation of experimental results than previously found, pointing the way to device optimization.
Terahertz pulse propagation using plasmon-polariton-like surface modes on structured conductive surfaces
Authors: Maier Stefan A. , Andrews Steve R.
Published: July 2006

The dispersion relation and confinement of plasmon-polariton-like terahertz surface modes sustained by a perfectly conducting planar surface patterned with a regular lattice of holes are studied using full-field three-dimensional numerical simulations. Edge coupling and subsequent surface guiding with subwavelength vertical confinement of the frequency components below the band edge of the surface mode is demonstrated for a broadband pulse with 0.5THz⩽f⩽2THz. Additionally, the constraints imposed by lattice constant and hole size on the creation of defect waveguides offering lateral confinement are discussed.
Catalyst-free synthesis of ZnO nanowall networks on Si3N4∕Si substrates by metalorganic chemical vapor deposition
Authors: Kim Sang-Woo , Fujita Shizuo , Yi Min-Su , Yoon Dae Ho
Published: July 2006

ZnO nanowall networks were synthesized on Si3N4∕Si (100) substrates at low growth temperature of 350°C by metalorganic chemical vapor deposition (MOCVD) without any help of metal catalysts. Depending on MOCVD-growth conditions, a large number of nanowalls with extremely small wall thicknesses below 10nm are formed into nanowalls with a thickness of about 20nm, resulting in the formation of two-dimensional nanowall networks. The ZnO nanowall networks were found to have a preferred c-axis orientation with a hexagonal structure in synchrotron x-ray scattering experiments. Room-temperature hydrogen incorporation into ZnO nanowall networks has been observed in photoluminescence measurements.