bluuebunny/crossref_metadata_2025 huggingface dataset:
Percutaneous radiofrequency ablation for the treatment of early stage hepatocellular carcinoma: A health technology assessment
Authors: Xie Xuanqian , Dendukuri Nandini , McGregor Maurice
Published: October 2010

Objectives:The aim of this study was to compare the clinical effectiveness and cost of percutaneous radiofrequency ablation (PRFA) and surgical resection (SRS) for the management of early stage Hepatocellular Carcinoma.

Methods:A systematic literature search of articles in English, French, and Chinese was performed using online databases. Only articles with patients classified as Child-Pugh Class A or B, with tumor size <5 cm were included. A meta-analysis was carried out to estimate the survival rate and disease-free survival rate following PRFA or SRS treatments. The cost of each treatment was estimated from the third party perspective. Univariate sensitivity analyses were used to study the relative importance of each component cost.

Results:We identified six studies (one randomized controlled trial (RCT) and five comparative cohort studies) meeting our inclusion criteria. There is good evidence that among Child-Pugh A patients for whom both SRS and PRFA are available options, survival rates following either procedure are comparable, while complications are more frequent and hospitalization longer following SRS. The evidence concerning recurrence rates and disease-free survival is less clear. Whereas the RCT indicates comparable outcomes with either procedure up to 3 years, the results of five cohort studies (with possible selection bias), particularly those with a mix of Child-Pugh A and B patients, favor the surgical option. SRS, costs approximately Canadian $8,275 more per case than PRFA.

Conclusions:Continuing doubts on this issue can only be resolved by a substantial RCT. Meanwhile, for early stage HCC patients classified as Child-Pugh A, who despite a possibly higher recurrence rate, prefer the less invasive PRFA to open surgery with its attendant risks, there is sufficient evidence to justify such a choice. For those classified as Child-Pugh (B) it is possible that overall survival is equally good with PRFA, but the evidence is less certain.
Supporting the use of health technology assessments in policy making about health systems
Authors: Lavis John N. , Wilson Michael G. , Grimshaw Jeremy M. , Haynes R. Brian , Ouimet Mathieu , Raina Parminder , Gruen Russell L. , Graham Ian D.
Published: October 2010

Objectives:The objective of this study is to profile the health technology assessments (HTAs) produced in Canada and other selected countries and assess their potential to inform policy making about health systems in jurisdictions other than the ones for which they were produced, and to develop and pilot test prototypes for packaging and assessing the relevance of HTAs for health system managers and policy makers.

Methods:We compiled an inventory of all HTAs that were produced by nine HTA agencies between September 2003 and August 2006; coded the title and abstract of each HTA according to the technologies assessed, methods used, and whether or not context-specific actionable messages were provided; developed a prototype for a structured, decision-relevant HTA summary and for a relevance-assessment form; and pilot-tested the prototypes using semistructured telephone interviews with a purposive sample of Canadian healthcare managers and policy makers.

Results:Our review of the 223 HTAs identified that: (i) 44 HTAs addressed health system arrangements (20 percent); (ii) 205 incorporated a systematic review (92 percent), whereas only 12 incorporated a sociopolitical assessment using explicit methods (5 percent); and (iii) 50 contained context-specific actionable messages (22 percent). Our interviews identified significant support for both the general idea of an HTA summary and the prototype's specific elements, but mixed views about using peer assessments of relevance.

Conclusions:Those involved in supporting the use of HTAs in policy making about health systems may wish to produce structured decision-relevant summaries for their systematic review-containing HTAs to increase the prospects for their HTAs being used outside the jurisdiction for which they were produced.
Transfer of conceptualization patterns in bilinguals: The construal of motion events in Turkish and German
Authors: DALLER MICHAEL H. , TREFFERS-DALLER JEANINE , FURMAN REYHAN
Published: October 2010

In the present article we provide evidence for the occurrence of transfer of conceptualization patterns in narratives of two German–Turkish bilingual groups. All bilingual participants grew up in Germany, but only one group is still resident in Germany (n = 49). The other, the returnees, moved back to Turkey after having lived in Germany for thirteen years (n = 35). The study is based on the theoretical framework for conceptual transfer outlined in Jarvis and Pavlenko (2008) and on the typology of satellite-framed and verb-framed languages developed by Talmy (1985, 1991, 2000a, b) and Slobin (1987, 1996, 2003, 2004, 2005, 2006). In the present study we provide evidence for the hypothesis that language structure affects the organization of information structure at the level of the Conceptualizer, and show that bilingual speakers’ conceptualization of motion events is influenced by the dominant linguistic environment in both languages (German for the group in Germany and Turkish for the returnees). The returnees follow the Turkish blueprints for the conceptualization of motion, in both Turkish and German event construals, whereas the German-resident bilinguals follow the German blueprints, when speaking German as well as Turkish. We argue that most of the patterns found are the result of transfer of conceptualization patterns from the dominant language of the environment.
Pepsi and Coca Cola in Delhi, India: availability, price and sales
Authors: Taylor Fiona C , Satija Ambika , Khurana Swati , Singh Gurpreet , Ebrahim Shah
Published: October 2010

Objective

India is experiencing increased consumption of sugar-sweetened carbonated drinks, consumption that may be associated with increased risk of type 2 diabetes and obesity. The aim of the study was to determine the availability, price and quantity sold of ‘Pepsi’ and ‘Coca Cola’ in their ‘regular’ and ‘diet’ forms in Delhi and London.

Design

A questionnaire about the availability, price and quantity sold per day of both regular and diet Pepsi and Coca Cola was devised and piloted. Using this, a survey of food and drink outlets within a 100 m radius of randomly selected Metro stations was conducted in both cities.

Subjects

Store vendors, owners and staff of food and drink outlets.

Setting

Delhi, India; London, United Kingdom.

Results

In Delhi, of the outlets stocking regular Pepsi and Coca Cola, only 34 % sold diet versions and these were more readily available in the most affluent areas than in the poorest areas (34 %v. 6 %,Z= 3·67,P< 0·001). This social patterning was not observed in London. Little price differential between regular and diet versions of Pepsi and Coca Cola was observed in Delhi; however, profit margins were better for regular, relative to diet, Coca Cola. Sales of regular products were significantly greater than those of diet products (P< 0·002).

Conclusions

Low availability of diet versions of Pepsi and Coca Cola in less affluent areas of Delhi is likely to exacerbate the obesity and diabetes trends. Price differentials to promote diet versions and other healthier or traditional low-energy drinks may be beneficial.
Assessment of EGM2008 in Europe using accurate astrogeodetic vertical deflections and omission error estimates from SRTM/DTM2006.0 residual terrain model data
Authors: Hirt C. , Marti U. , Bürki B. , Featherstone W. E.
Published: October 2010

We assess the new EGM2008 Earth gravitational model using a set of 1056 astrogeodetic vertical deflections over parts of continental Europe. Our astrogeodetic vertical deflection data set originates from zenith camera observations performed during 1983–2008. This set, which is completely independent from EGM2008, covers, e.g., Switzerland, Germany, Portugal and Greece, and samples a variety of topography – level terrain, medium elevated and rugged Alpine areas. We describe how EGM2008 is used to compute vertical deflections according to Helmert's (surface) definition. Particular attention is paid to estimating the EGM2008 signal omission error from residual terrain model (RTM) data. The RTM data is obtained from the Shuttle Radar Topography Mission (SRTM) elevation model and the DTM2006.0 high degree spherical harmonic reference surface. The comparisons between the astrogeodetic and EGM2008 vertical deflections show an agreement of about 3 arc seconds (root mean square, RMS). Adding omission error estimates from RTM to EGM2008 significantly reduces the discrepancies from the complete European set of astrogeodetic deflections to 1 arc second (RMS). Depending on the region, the RMS errors vary between 0.4 and 1.5 arc seconds. These values not only reflect EGM2008 commission errors, but also short‐scale mass‐density anomalies not modelled from the RTM data. Given (1) formally stated EGM2008 commission error estimates of about 0.6–0.8 arc seconds for vertical deflections, and (2) that short‐scale mass‐density anomalies may affect vertical deflections by about 1 arc second, the agreement between EGM2008 and our astrogeodetic deflection data set is very good. Further focus is placed on the investigation of the high‐degree spectral bands of EGM2008. As a general conclusion, EGM2008 – enhanced by RTM data – is capable of predicting Helmert vertical deflections at the 1 arc second accuracy level over Europe.
Occurrence, liquid water content, and fraction of supercooled water clouds from combined CALIOP/IIR/MODIS measurements
Authors: Hu Yongxiang , Rodier Sharon , Xu Kuan‐man , Sun Wenbo , Huang Jianping , Lin Bing , Zhai Pengwang , Josset Damien
Published: October 2010

The CALIOP depolarization measurements, combined with backscatter intensity measurements, are effective in discriminating between water clouds and ice clouds. The same depolarization measurements can also be used for estimating liquid water content information. Using cloud temperature information from the collocated infrared imaging radiometer measurements and cloud water paths from collocated MODIS measurements, this study compiles global statistics of the occurrence frequency, liquid water content, liquid water path, and their temperature dependence. For clouds with temperatures between −40°C and 0°C, the liquid phase fractions and liquid water paths are significantly higher than the ones from previous studies using passive remote sensing measurements. At midlatitudes, the occurrence of liquid phase clouds at temperatures between −40°C and 0°C depends jointly on both cloud height and cloud temperature. At high latitudes, more than 95% of low‐level clouds with temperatures between −40°C and 0°C are water clouds. Supercooled water clouds are mostly observed over ocean near the storm‐track regions and high‐latitude regions. Supercooled water clouds over land are observed in the Northern Hemisphere over Europe, East Asia, and North America, and these are the supercooled water clouds with highest liquid water contents. The liquid water content of all supercooled water clouds is characterized by a Gamma (Γ) distribution. The mode values of liquid water content are around 0.06 g/m3 and are independent of cloud temperature. For temperatures warmer than −15°C, mean value of the liquid water content is around 0.14 g/m3. As the temperature decreases, the mean cloud liquid water content also decreases. These results will benefit cloud models and cloud parameterizations used in climate models in improving their ice‐phase microphysics parameterizations and the aviation hazard forecast.
Lidar measurements of the Kasatochi aerosol plume in August and September 2008 in Ny‐Ålesund, Spitsbergen
Authors: Hoffmann A. , Ritter C. , Stock M. , Maturilli M. , Eckhardt S. , Herber A. , Neuber R.
Published: October 2010

The eruptions of the Kasatochi volcano on 7 and 8 August 2008 led to an enhanced stratospheric aerosol load which was studied with the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar (MPL) at the French‐German Arctic Research Base AWIPEV in Ny‐Ålesund, Spitsbergen at 78.55°N, 11.56°E. During all KARL measurements from 15 August to 24 September 2008 (approximately 30 h of data), we detected distinct layers of enhanced aerosol backscatter in the lower stratosphere and the tropopause region, whose origination at the Kasatochi site can be shown by trajectory calculations. We found a 125% increase in aerosol optical depth compared to the mean values from 2004 to 2007 at 3 weeks after the eruption, validated by sunphotometer measurements. Differences in volume depolarization and color ratio signatures of the layers indicate a sinking movement of the bigger particles to the layer bottom. Furthermore, within higher stratospheric aerosol layers monitored after 25 August 2008, we observed the volume depolarization maximum to be up to 0.8 km below the backscatter maximum. Backscatter and depolarization measurements from 1 September 2008, on which data were collected over 13 h during daylight and darkness, are analyzed in detail. Calculations of the lidar ratio in the lowest aerosol layer as well as the estimation of microphysical parameters of the aerosol particles were performed.
A new global gridded data set of CO2 emissions from fossil fuel combustion: Methodology and evaluation
Authors: Rayner P. J. , Raupach M. R. , Paget M. , Peylin P. , Koffi E.
Published: October 2010

We describe a system for constraining the spatial distribution of fossil fuel emissions of CO2. The system is based on a modified Kaya identity which expresses emissions as a product of areal population density, per capita economic activity, energy intensity of the economy, and carbon intensity of energy. We apply the methodology of data assimilation to constrain such a model with various observations, notably, the statistics of national emissions and data on the distribution of nightlights and population. We hence produce a global, annual emission field at 0.25° resolution. Our distribution of emissions is smoother than that of the population downscaling traditionally used to describe emissions. Comparison with the Vulcan inventory suggests that the assimilated product performs better than downscaling for distributions of either population or nightlights alone for describing the spatial structure of emissions over the United States. We describe the complex structure of uncertainty that arises from combining pointwise and area‐integrated constraints. Uncertainties can be as high as 50% at the pixel level and are not spatially independent. We describe the use of 14CO2 measurements to further constrain national emissions. Their value is greatest over large countries with heterogeneous emissions. Generated fields may be found online (http://ffdas.org/).
The importance of being coupled: Stable states and catastrophic shifts in tidal biomorphodynamics
Authors: Marani Marco , D'Alpaos Andrea , Lanzoni Stefano , Carniello Luca , Rinaldo Andrea
Published: October 2010

We describe and apply a point model of the joint evolution of tidal landforms and biota which incorporates the dynamics of intertidal vegetation; benthic microbial assemblages; erosional, depositional, and sediment exchange processes; wind‐wave dynamics, and relative sea level change. Alternative stable states and punctuated equilibria emerge, characterized by possible sudden transitions of the system state, governed by vegetation type, disturbances of the benthic biofilm, sediment availability, and marine transgressions or regressions. Multiple stable states are suggested to result from the interplay of erosion, deposition, and biostabilization, providing a simple explanation for the ubiquitous presence of the typical landforms observed in tidal environments worldwide. The main properties of accessible equilibrium states prove robust with respect to specific modeling assumptions and are thus identified as characteristic dynamical features of tidal systems. Halophytic vegetation emerges as a key stabilizing factor through wave dissipation, rather than a major trapping agent, because the total inorganic deposition flux is found to be largely independent of standing biomass under common supply‐limited conditions. The organic sediment production associated with halophytic vegetation represents a major contributor to the overall deposition flux, thus critically affecting the ability of salt marshes to keep up with high rates of relative sea level rise. The type and number of available equilibria and the possible shifts among them are jointly driven and controlled by the available suspended sediment, the rate of relative sea level change, and vegetation and microphytobenthos colonization. The explicit description of biotic and abiotic processes thus emerges as a key requirement for realistic and predictive models of the evolution of a tidal system as a whole. The analysis of such coupled processes finally indicates that hysteretic switches between stable states arise because of differences in the threshold values of relative sea level rise inducing transitions from vegetated to unvegetated equilibria and vice versa.
A simulation and theoretical study of energy transport in the event of MHD Kelvin‐Helmholtz instability
Authors: Lai S. H. , Lyu L. H.
Published: October 2010

Surface waves developed from the Kelvin‐Helmholtz (K‐H) instability perturb the ambient plasma and radiate waves that extract surface‐wave energy. In magnetohydrodynamic (MHD) plasma, the fast‐mode waves can propagate across the magnetic field lines. The fast‐mode waves emitted from the surface perturbations should play an important role in transporting the surface‐wave energy away from the velocity shear layer. Thus, the energy transported by the K‐H instability should not be confined near the velocity shear layer. In this study, energy transport in the events of K‐H instabilities is studied by the two‐dimensional MHD simulation. Our simulation results indicate that most of the energy flux is confined in the vicinity of the velocity shear layer when the fast‐mode Mach number of the surface wave is less than one. However, a small amount of the surface‐wave energy is transported away from the velocity shear layer by the fast‐mode waves. A considerable amount of the surface‐wave energy is transported away from the velocity shear layer with the expanding of the fast‐mode Mach‐cone‐like plane waves when the fast‐mode Mach number of the surface wave is greater than one. It is shown that the fast‐mode Mach‐cone‐like plane waves can transport the surface‐wave energy away from the velocity shear layer efficiently. In this study, we also find that the energy transport velocity obtained from our simulation results is approximately equal to the group velocity of the fast‐mode wave. Applications of our simulation results to the magnetosphere are also discussed.
Impact of sudden stratospheric warmings on equatorial ionization anomaly
Authors: Goncharenko L. P. , Coster A. J. , Chau J. L. , Valladares C. E.
Published: October 2010

We investigate the ionospheric response to several stratospheric sudden warming events which occurred in Northern Hemisphere winters of 2008 and 2009 during solar minimum conditions. We use GPS total electron content data in a broad latitudinal region at ±40° geographic latitude and a single longitude, 75°W. In all cases, we find a strong daytime ionospheric response to stratospheric sudden warmings. This response is characterized by a semidiurnal character, large amplitude, and persistence of perturbations for up to 3 weeks after the peak in high‐latitude stratospheric temperatures. The ionospheric perturbations at the lower latitudes usually begin a few days after the peak in stratospheric temperature and are observed as an enhancement of the equatorial ionization anomaly (EIA) in the morning sector and a suppression of the EIA in the afternoon sector. There is also evidence of a secondary enhancement in the postsunset hours. Once observed in the low latitudes, the phase of semidiurnal perturbations progressively shifts to later local times in subsequent days. This progressive shift occurs at a different rate for different stratospheric warming events. The large magnitude and persistence of ionospheric perturbations, together with the predictability of stratospheric sudden warmings several days in advance, present an opportunity to investigate these phenomena in a systematic manner which may eventually lead to a multiday forecast of low‐latitude ionosphere conditions.
Numerical simulation of the 12 May 1997 CME Event: The role of magnetic reconnection
Authors: Cohen O. , Attrill G. D. R. , Schwadron N. A. , Crooker N. U. , Owens M. J. , Downs C. , Gombosi T. I.
Published: October 2010

We perform a numerical study of the evolution of a Coronal Mass Ejection (CME) and its interaction with the coronal magnetic field based on the 12 May 1997, CME event using a global MagnetoHydroDynamic (MHD) model for the solar corona. The ambient solar wind steady‐state solution is driven by photospheric magnetic field data, while the solar eruption is obtained by superimposing an unstable flux rope onto the steady‐state solution. During the initial stage of CME expansion, the core flux rope reconnects with the neighboring field, which facilitates lateral expansion of the CME footprint in the low corona. The flux rope field also reconnects with the oppositely orientated overlying magnetic field in the manner of the breakout model. During this stage of the eruption, the simulated CME rotates counter‐clockwise to achieve an orientation that is in agreement with the interplanetary flux rope observed at 1 AU. A significant component of the CME that expands into interplanetary space comprises one of the side lobes created mainly as a result of reconnection with the overlying field. Within 3 hours, reconnection effectively modifies the CME connectivity from the initial condition where both footpoints are rooted in the active region to a situation where one footpoint is displaced into the quiet Sun, at a significant distance (≈1R⊙) from the original source region. The expansion and rotation due to interaction with the overlying magnetic field stops when the CME reaches the outer edge of the helmet streamer belt, where the field is organized on a global scale. The simulation thus offers a new view of the role reconnection plays in rotating a CME flux rope and transporting its footpoints while preserving its core structure.
Backscattered solar wind protons by Phobos
Authors: Futaana Y. , Barabash S. , Holmström M. , Fedorov A. , Nilsson H. , Lundin R. , Dubinin E. , Fränz M.
Published: October 2010

We report Mars Express (MEX) measurements showing that the regolith‐covered Phobos surface backscatters 0.5%–10% of the impinging solar wind protons. Backscattered protons with an energy corresponding to 30%–40% of the solar wind energy injected in the flow are picked up by the solar wind and may cause field disturbances and wave activity. Since a similar backscattering of solar wind protons was observed and reported at the Moon, the backscattering of the solar wind particles is a typical physical process for regolith‐covered bodies in space, even though the regolith is highly porous and it has been thought that almost 100% of the solar wind protons are implanted.
Seasonal variations of diacids, ketoacids, and α‐dicarbonyls in aerosols at Gosan, Jeju Island, South Korea: Implications for sources, formation, and degradation during long‐range transport
Authors: Kundu Shuvashish , Kawamura Kimitaka , Lee Meehye
Published: October 2010

Aerosol samples (n = 84) were collected continuously from April 2003 to April 2004 at Gosan site in Jeju Island, South Korea. The samples were analyzed for diacids, ketoacids, and α‐dicarbonyls, as well as organic carbon (OC), elemental carbon (EC), water‐soluble organic carbon (WSOC), and water‐soluble inorganic ions. Oxalic acid (C2) was the most abundant followed by malonic acid (C3) in all the seasons. The mean concentration (784 ng m−3) of total diacids (C2–C12) and their relative abundances in total organic species detected, OC and WSOC were found to be the highest in summer, whereas those of ketoacids and dicarbonyls were the highest in winter. The annual mean contributions of diacids, ketoacids, and dicarbonyls to WSOC are 12, 1, and 0.4%, respectively. They are several times higher than those reported in East Asia from which air masses are transported to Gosan, indicating an importance of photochemical processing of aerosols during a long‐range transport. Diacids and related compounds show different seasonal variations, suggesting their season‐specific sources and photochemical processing. This study demonstrates an enhanced photochemical production and degradation of water‐soluble organics in summer. In contrast, higher positive correlations between combustion tracers (non‐sea‐salt K+ and EC) and diacids and related compounds were observed in the winter, pointing out higher emission of diacids and related compounds or their precursors from fossil fuel/biomass burning.
Global validation of empirically corrected EP‐Total Ozone Mapping Spectrometer (TOMS) total ozone columns using Brewer and Dobson ground‐based measurements
Authors: Antón M. , Koukouli M. E. , Kroon M. , McPeters R. D. , Labow G. J. , Balis D. , Serrano A.
Published: October 2010

This article focuses on the global‐scale validation of the empirically corrected Version 8 total ozone column data set acquired by the NASA Total Ozone Mapping Spectrometer (TOMS) during the period 1996–2004 when this instrument was flying aboard the Earth Probe (EP) satellite platform. This analysis is based on the use of spatially co‐located, ground‐based measurements from Dobson and Brewer spectrophotometers. The original EP‐TOMS V8 total ozone column data set was also validated with these ground‐based measurements to quantify the improvements made by the empirical correction that was necessary as a result of instrumental degradation issues occurring from the year 2000 onward that were uncorrectable by normal calibration techniques. EP‐TOMS V8‐corrected total ozone data present a remarkable improvement concerning the significant negative bias of around ∼3% detected in the original EP‐TOMS V8 observations after the year 2000. Neither the original nor the corrected EP‐TOMS satellite total ozone data sets show a significant dependence on latitude. In addition, both EP‐TOMS satellite data sets overestimate the Brewer measurements for small solar zenith angles (SZA) and underestimate for large SZA, explaining a significant seasonality (∼1.5%) for cloud‐free and cloudy conditions. Conversely, relative differences between EP‐TOMS and Dobson present almost no dependence on SZA for cloud‐free conditions and a strong dependence for cloudy conditions (from +2% for small SZA to −1% for high SZA). The dependence of the satellite ground‐based relative differences on total ozone shows good agreement for column values above 250 Dobson units. Our main conclusion is that the upgrade to TOMS V8‐corrected total ozone data presents a remarkable improvement. Nevertheless, despite its quality, the EP‐TOMS data for the period 2000–2004 should not be used as a source for trend analysis since EP‐TOMS ozone trends are empirically corrected using NOAA‐16 and NOAA‐17 solar backscatter ultraviolet/2 data as external references, and therefore, they are no longer considered as independent observations.
Structural insights into the catalytic mechanism of the yeast pyridoxal 5-phosphate synthase Snz1
Authors: Zhang Xuan , Teng Yan-Bin , Liu Jian-Ping , He Yong-Xing , Zhou Kang , Chen Yuxing , Zhou Cong-Zhao
Published: October 2010

In most eubacteria, fungi, apicomplexa, plants and some metazoans, the active form of vitamin B6, PLP (pyridoxal 5-phosphate), is de novo synthesized from three substrates, R5P (ribose 5-phosphate), DHAP (dihydroxyacetone phosphate) and ammonia hydrolysed from glutamine by a complexed glutaminase. Of the three active sites of DXP (deoxyxylulose 5-phosphate)independent PLP synthase (Pdx1), the R5P isomerization site has been assigned, but the sites for DHAP isomerization and PLP formation remain unknown. In the present study, we present the crystal structures of yeast Pdx1/Snz1, in apo-, G3P (glyceraldehyde 3-phosphate)- and PLP-bound forms, at 2.3, 1.8 and 2.2 Å (1 Å=0.1 nm) respectively. Structural and biochemical analysis enabled us to assign the PLP-formation site, a G3P-binding site and a G3P-transfer site. We propose a putative catalytic mechanism for Pdx1/Snz1 in which R5P and DHAP are isomerized at two distinct sites and transferred along well-defined routes to a final destination for PLP synthesis.
Postconditioning attenuates myocardial injury by reducing nitro-oxidative stressin vivoin rats and in humans
Authors: Fan Qian , Yang Xin-Chun , Liu Yu , Wang Le-Feng , Liu Sheng-Hui , Ge Yong-Gui , Chen Mu-Lie , Wang Wen , Zhang Li-Ke , Irwin Michael G. , Xia Zhengyuan
Published: October 2010

In the present study, we hypothesized that postcon (postconditioning) confers cardioprotection in vivo by reducing the production of ONOO− (peroxynitrite) and nitro-oxidative stress subsequent to the inhibition of the iNOS (inducible NO synthase). Patients with AMI (acute myocardial infarct) were randomly assigned to undergo percutaneous coronary intervention without (control) or with ischaemic postcon by three episodes of 30-s inflation and 30-s deflation of the angioplasty balloon. Animal models of MI/R (myocardial ischaemia/reperfusion) injury were induced in rats by occluding the left coronary artery for 40 min followed by 4-h reperfusion. Rats were randomized to receive vehicle, postcon (three cycles of 10-s reperfusion and 10-s coronary re-occlusion preceding full reperfusion), the selective iNOS inhibitor 1400W or postcon plus 3-morpholinosydnonimine (an ONOO− donor). Postcon in patients reduced iNOS activity in white blood cells, decreased plasma nitrotyrosine, a fingerprint of ONOO− and an index of nitro-oxidative stress, and improved cardiac function (P<0.01 compared with control). In rats, postcon reduced post-ischaemic myocardial iNOS activity and nitrotyrosine formation, reduced myocardial infarct size (all P<0.05 compared with control) and improved cardiac function. Administration of 1400W resembled, whereas 3-morpholinosydnonimine abolished, the effects of postcon. In conclusion, reduction in ONOO−-induced nitro-oxidative stress subsequent to the inhibition of iNOS represents a major mechanism whereby postcon confers cardioprotection in vivo.
PHYLOGENETIC ANALYSIS OF 32 STRAINS OFVAUCHERIA(XANTHOPHYCEAE) USING THErbcL GENE AND ITS TWO FLANKING SPACER REGIONS1
Authors: Andersen Robert A. , Bailey J. Craig
Published: October 2010

The completerbcL gene was sequenced for 21 species and 32 strains ofVaucheriaand for five other Xanthophyceae (Asterosiphon dichotomus(Kützing) Rieth,Botrydium becharianumVischer,B. cystosumVischer,B. stoloniferumMitra,Tribonema intermixtumPascher). ThepsbA‐rbcL spacer, upstream of therbcL gene, and the RUBISCO spacer between therbcL andrbcS genes were also completely sequenced for theVaucheriastrains andAsterosiphon.ThepsbA‐rbcL spacer was the most variable region that was sequenced, and only the 3′ end of the spacer could be aligned. Phylogenetic analyses (maximum parsimony, neighbor joining, and maximum likelihood) were conducted using the DNA sequence and the amino acid sequence for therbcL gene, and a second analysis was conducted using a portion of thepsbA‐rbcL spacer +rbcL gene + RUBISCO spacer. All analyses showed thatVaucheriaspecies formed monophyletic clades that corresponded with morphologically based subgeneric sections, including the section Racemosae. Species producing a gametophore (= fruiting branch, bearing both an antheridium and oogonium) formed a monophyletic clade in all analyses. The nongametophore species sometimes formed a monophyletic clade but other times formed a basal grade. Pair‐wise comparisons of nucleotides and amino acids showed that for some species, numerous nucleotide changes resulted in relatively few amino acid changes. Consequently, phylogenetic analysis of the amino acids produced numerous trees, which in a strict consensus tree resulted in numerous polychotomies. An original strain ofV. terrestristhat was deposited in two culture collections over 25 years ago had identical sequences, suggesting no rapid change was occurring in the sequenced regions. Two strains ofV. prona, isolated from Europe and North America, had identical sequences. Other species, for which two or more strains were examined, had different sequences. These results suggest that cryptic species complexes exist withinVaucheriabecause therbcL gene is a conservative gene that is identical in other protists.
PHYLOGEOGRAPHIC STUDIES IN THE TROPICAL SEAWEED CLADOPHOROPSIS MEMBRANACEA (CHLOROPHYTA, ULVOPHYCEAE) REVEAL A CRYPTIC SPECIES COMPLEX1
Authors: Van Der Strate Han J. , Boele‐Bos Stella A. , Olsen Jeanine L. , Van De Zande Louis , Stam Wytze T.
Published: October 2010

The seaweed Cladophoropsis membranacea (Hofman Bang ex. C. Agardh) Børgesen is a widely distributed species on coral reefs and along rocky coastlines throughout the tropics and subtropics. In a recent population‐level survey openface>1600 individuals with eight microsatellite loci, a number of isolates from biogeographically disjunct locations could not be amplified for any of the loci. Nonamplifiable and amplifiable isolates co‐occurred within the Canary Islands, Cape Verde Islands, and in the Caribbean. These unexpected results led to question whether or not C. membranacea is a single species. Phylogenetic relationships were evaluated using rDNA ITS1 and ITS2 sequence comparisons from 42 isolates sampled from a subset of 30 of the 66 locations. Four well‐supported clades were identified. Sequence divergence within clades was <1%, whereas between‐clade divergence was 2%–3%. Intraindividual variation was extremely low with no effects on the analysis. A strong, but imperfect, correspondence was found between ITS clades and amplifiable microsatellite loci. It is concluded that C. membranacea consists of three cryptic species. Using Pacific isolates as an outgroup, the most basal clade included the Central Canary Islands, Cape Verde, and Bonaire (Caribbean) isolates and thus spanned the widest latitude. Two derived sister clades consisted of a southern transtropical group stretching across the SE Caribbean to the Cape Verde Islands and African coast (but not the Canary Islands) and a NE‐Canary Island‐Mediterranean clade that also included the Red Sea. The detection of overlapping biogeographic distributions highlights the importance of ecotypic differentiation with respect to temperature and the importance of shifting sea surface isotherms that have driven periodic extinctions and recolonizations of the Canary Islands—a crossroads of marine floral exchange—since the last glacial maximum.
EFFECTS OF UV RADIATION ON A CHLOROPHYTE ALGA (SCENEDESMUS SP.) ISOLATED FROM THE FUMAROLE FIELDS OF MT. EREBUS, ANTARCTICA1
Authors: Lesser Michael P. , Barry Thomas M. , Banaszak Anastazia T.
Published: October 2010

Acclimation to UV radiation (UVR) was examined in a unicellular chlorophyte isolated from fumarole fields adjacent to Mt. Erebus, Antarctica. Long‐term exposure to UVR (14 days) initially reduced the efficiency of photosynthetic energy conversion measured as the dark adapted quantum yield of PSII fluorescence (Fv/Fm) when compared with cultures not exposed to UVR. However, the UVR exposed cultures recovered to pre‐UVR exposure levels of photosynthetic efficiency by the end of the experimental period. Additionally, neither growth rates nor cell size were significantly affected by exposure to UVR. In contrast, the maximum rate of carbon fixation on a chl a basis was significantly reduced at the end of the experiment and was accompanied by a significant decrease in chl a concentrations. These results suggest a transient effect of UVR on primary photochemistry consistent with damage to PSII, possibly at the D1 protein, with more chronic effects on carbon fixation that did affect maximum photosynthetic capacity. Ultrastructural and molecular (18s rDNA) data show that this isolate from the fumoral fields of Mt. Erebus, Antarctica is a member of the genus Scenedesmus.
JET‐SUSPENDED, CALCITE‐BALLASTED CYANOBACTERIAL WATERWARTS IN A DESERT SPRING1
Authors: Garcia‐Pichel Ferran , Wade Brian D. , Farmer Jack D.
Published: October 2010

We describe a population of colonial cyanobacteria (waterwarts) that develops as the dominant primary producer in a bottom‐fed, O2‐poor, warm spring in the Cuatro Ciénegas karstic region of the Mexican Chihuahuan Desert. The centimeter‐sized waterwarts were suspended within a central, conically shaped, 6‐m deep well by upwelling waters. Waterwarts were built by anAphanothece‐like unicellular cyanobacterium and supported a community of epiphytic filamentous cyanobacteria and diatoms but were free of heterotrophic bacteria inside. Sequence analysis of 16S rRNA genes revealed that this cyanobacterium is only distantly related to several strains of other unicellular cyanobacteria (Merismopedia, Cyanothece, Microcystis). Waterwarts contained orderly arrangements of mineral crystallites, made up of microcrystalline low‐magnesium calcite with high levels of strontium and sulfur. Waterwarts were 95.9% (v/v) glycan, 2.8% cells, and 1.3% mineral grains and had a buoyant density of 1.034 kg·L−1. An analysis of the hydrological properties of the spring well and the waterwarts demonstrated that both large colony size and the presence of controlled amounts of mineral ballast are required to prevent the population from being washed out of the well. The unique hydrological characteristics of the spring have likely selected for both traits. The mechanisms by which controlled nucleation of extracellular calcite is achieved remain to be explored.
PARASITISM OF PHOTOSYNTHETIC DINOFLAGELLATES BY THREE STRAINS OF AMOEBOPHRYA (DINOPHYTA): PARASITE SURVIVAL, INFECTIVITY, GENERATION TIME, AND HOST SPECIFICITY1
Authors: Coats D. Wayne , Park Myung Gil
Published: October 2010

Amoebophrya ceratii (Koeppen) Cachon is an obligate parasite of dinoflagellates and may represent a species complex. However, little is known about the biology and host range of different strains of Amoebophrya Cachon. Here, we determined parasite generation time and dinospore infectivity, survival, and ability to infect nonprimary hosts for strains of Amoebophrya from Akashiwo sanguinea (Hirasaka) G. Hansen et Moestrup, Gymnodinium instriatum (Freudenthal et Lee) Coats comb. nov., and Karlodinium micrum (Leadbeater et Dodge) J. Larsen. Akashiwo sanguinea was readily infected, with parasite prevalence reaching 100% in dinospore:host inoculations above a 10:1 ratio. Parasitism also approached 100% in G. instriatum, but only when inoculations exceeded a 40:1 ratio. Karlodinium micrum appeared partially resistant to infection, as parasite prevalence saturated at 92%. Parasite generation time differed markedly among Amoebophrya strains. Survival and infectivity of dinospores decreased over time, with strains from G. instriatum and A. sanguinea unable to initiate infections after 2 and 5 days, respectively. By contrast, dinospores from Amoebophrya parasitizing K. micrum remained infective for up to 11 days. Akashiwo sanguinea and G. instriatum were not infected when exposed to dinospores from nonprimary Amoebophrya strains. Karlodinium micrum, however, was attacked by dinospores of Amoebophrya from the other two host species, but infections failed to reach maturity. Observed differences in host–parasite biology support the hypothesis that Amoebophrya ceratii represents a complex of host‐specific species. Results also suggest that Amoebophrya strains have evolved somewhat divergent survival strategies that may encompass sexuality, heterotrophy during the “free‐living” dinospore stage, and dormancy.
ISLANDINIUM BREVISPINOSUM SP. NOV. (DINOFLAGELLATA), A NEW ORGANIC‐WALLED DINOFLAGELLATE CYST FROM MODERN ESTUARINE SEDIMENTS OF NEW ENGLAND (USA)1
Authors: Pospelova Vera , Head Martin J.
Published: October 2010

Modern estuarine environments remain underexplored for dinoflagellate cysts, despite a rapidly increasing knowledge of cyst distributions in open marine sediments. A study of modern estuarine sediments in New England has revealed the presence of Islandinium brevispinosum sp. nov., a new organic‐walled dinoflagellate cyst that is locally common and probably of heterotrophic affinity. Resistance of this cyst to standard palynological processing indicates its geological preservability, although fossils are not yet known. Previously assigned species of the genus Islandinium are characteristic of polar and subpolar environments today and cold paleoenvironments in the Quaternary. The present record of I. brevispinosum extends the ecological and geographical range of this genus into the warm temperate zone, where I. brevispinosum occupies specific environments with reduced salinities and elevated nutrient levels.
SYSTEMATICS OF THE HILDENBRANDIALES (RHODOPHYTA): GENE SEQUENCE AND MORPHOMETRIC ANALYSES OF GLOBAL COLLECTIONS1
Authors: Sherwood Alison R. , Sheath Robert G.
Published: October 2010

Fifty‐seven collections of marine and freshwater Hildenbrandia from North America, South America, Europe, and Africa were compared with 21 type and historically important specimens using multivariate morphometrics. Additionally, phylogenetic analyses of 48 specimens of Hildenbrandia and two specimens of Apophlaea were carried out based on sequences of the rbcL chloroplast gene and the nuclear 18S rRNA gene. Morphometric analyses based on vegetative cell and filament dimensions distinguished two groups of freshwater Hildenbrandia specimens, the first corresponding to those collections from North America and the Philippines and the second to those from Europe and the Canary Islands. The first group had smaller mean cell and filament dimensions (cells 4.0 × 4.4 μm, filaments 46.5 μm) and corresponded to H. angolensis, whereas the second group had larger mean dimensions (cells 5.8 × 6.6 μm, filaments 55.3 μm) and represented H. rivularis. Marine specimens were morphometrically distinguishable into two groups based on tetrasporangial division pattern as well as other thallus characters. However, measurements and character determinations of some type specimens differed greatly from the original descriptions, and thus further work to determine the stability of these characters is required. Phylogenetic reconstruction based on the 18S rRNA gene and rbcL gene sequence data generally demonstrated separation of the marine and freshwater forms of Hildenbrandia, with some marine taxa forming monophyletic groups (e.g. H. lecannellieri and H. occidentalis) and others forming paraphyletic groups (e.g. H. rubra). The two specimens of Apophlaea formed a monophyletic group within the paraphyletic genus Hildenbrandia.
INTERACTIONS BETWEEN UV RADIATION AND TEMPERATURE LIMIT INFERENCES FROM SINGLE‐FACTOR EXPERIMENTS1
Authors: Hoffman Jennifer R. , Hansen Lara J. , Klinger Terrie
Published: October 2010

The global environment is changing. Substantial shifts in temperature, rainfall, cloud cover, and UV radiation (UVR) are all predicted as a result of anthropogenic activity. Although the actual and potential effects of changes in single environmental variables are being studied intensively, the interactive effects of multiple stressors have received little attention. Here we offer the first experimental evidence of interactive effects between UVR and temperature on germination and growth in multicellular organisms. To address the question of how temperature affects survival and growth of organisms in the presence of UVR, we exposed early life stages of two species of intertidal algae, Alaria marginata Postels et Ruprecht and Fucus gardneri Silva, to four levels of UVR at three temperatures for 56 h. PAR and day length (12:12‐h light:dark) were held constant across all treatments. UVR levels bracketed natural levels, and temperatures were within the range of ambient temperatures. Designated endpoints were germination rate and cell number, and we recorded mortality where survival was nil. Our results support the hypothesis that temperature mediates the net biological effect of UVR and vice versa. For instance, spores of A. marginata were able to survive and grow at 15° C at all UV levels and at 10° C in the absence of UVR but were unable to survive at 10° C in the presence of high levels of UVR. Our results suggest that the ability to predict the effects of global change hinges on understanding interactions among environmental variables, imposing strict limits on inferences made from single‐factor experiments.
NOVEL STEROLS OF THE TOXIC DINOFLAGELLATE KARENIA BREVIS (DINOPHYCEAE): A DEFENSIVE FUNCTION FOR UNUSUAL MARINE STEROLS?1
Authors: Giner José‐Luis , Faraldos Juan A. , Boyer Gregory L.
Published: October 2010

The “red tide” organism Karenia brevis (Davis) Hansen & Moestrup (=Gymnodinium breve Davis) produces a mixture of brevetoxins, potent neurotoxins responsible for neurotoxic shellfish poisoning in humans and massive fish kills in the Gulf of Mexico and the southern Atlantic coast of the United States. The sterol composition of K. brevis was found to be a mixture of six novel and rare Δ8(14) sterols. The two predominant sterols, (24R)‐4α‐methylergosta‐8(14), 22‐dienol and (24R)‐4α‐methyl‐27‐norergosta‐8(14), 22‐dienol, were named gymnodinosterol and brevesterol and represent potentially useful biomarkers for K. brevis. A possible function for such unusual marine sterols is proposed whereby structural modifications render the sterols non‐nutritious to marine invertebrates, reducing predation and thereby enhancing the ability of the dinoflagellates to form massive blooms.
THE ROLE OF PERIPHYTON IN PHOSPHORUS RETENTION IN SHALLOW FRESHWATER AQUATIC SYSTEMS
Authors: Dodds Walter K.
Published: October 2010

Eutrophication caused by phosphorus (P) leads to water quality problems in aquatic systems, particularly freshwaters, worldwide. Processing of nutrients in shallow habitats removes P from water naturally and periphyton influences P removal from the water column in flowing waters and wetlands. Periphyton plays several roles in removing P from the water column, including P uptake and deposition, filtering particulate P from the water, and attenuating flow, which decreases advective transport of particulate and dissolved P from sediments. Furthermore, periphyton photosynthesis locally increases pH by up to 1 unit, which can lead to increased precipitation of calcium phosphate, concurrent deposition of carbonate‐phosphate complexes, and long‐term burial of P. Actively photosynthesizing periphyton can cause super‐saturated O2 concentrations near the sediment surface encouraging deposition of metal phosphates. However, anoxia associated with periphyton respiration at night may offset this effect. Linking the small‐scale functional role of periphyton to ecosystem‐level P retention will require more detailed studies in a variety of ecosystems or large mesocosms. A case study from the Everglades illustrates the importance of considering the role of periphyton in P removal from wetlands. In general, periphyton tends to increase P retention and deposition. In pilot‐scale constructed periphyton‐dominated wetlands in South Florida, about half of the inflowing total P was removed.