bluuebunny/crossref_metadata_2025 huggingface dataset:
Metabolite ligands of estrogen receptor-β reduce primate coronary hyperreactivity
Authors: Mishra Rajesh G. , Stanczyk Frank Z. , Burry Kenneth A. , Oparil Suzanne , Katzenellenbogen Benita S. , Nealen Michele L. , Katzenellenbogen John A. , Hermsmeyer R. Kent
Published: September 2005

Previous reports showed that 17β-estradiol implants attenuate in vivo coronary hyperreactivity (CH), characterized by long-duration vasoconstrictions (in coronary angiographic experiments), in menopausal rhesus monkeys. Prolonged Ca2+ contraction signals that correspond with CH in coronary vascular muscle cells (VMC) to the same dual-constrictor stimulus, serotonin + the thromboxane analog U-46619, in estrogen-deprived VMC were suppressed by >72 h in 17β-estradiol. The purpose of this study was to test whether an endogenous estrogen metabolite with estrogen receptor-β (ER-β) binding activity, estriol (E3), suppresses in vivo and in vitro CH. E3 treatment in vivo for 4 wk significantly attenuated the angiographically evaluated vasoconstrictor response to intracoronary serotonin + U-46619 challenge. In vitro treatment of rhesus coronary VMC for >72 h with nanomolar E3 attenuated late Ca2+ signals. This reduction of late Ca2+ signals also appeared after >72 h of treatment with subnanomolar 5α-androstane-3β,17β-diol (3β-Adiol), an endogenous dihydrotestosterone metabolite with ER-β binding activity. R,R-tetrahydrochrysene, a selective ER-β antagonist, significantly blocked the E3- and 3β-Adiol-mediated attenuation of late Ca2+ signal increases. ER-β and thromboxane-prostanoid receptor (TPR) were coexpressed in coronary arteries and aorta. In vivo E3 treatment attenuated aortic TPR expression. Furthermore, in vitro treatment with E3 or 3β-Adiol downregulated TPR expression in VMC, which was blocked for both agonists by pretreatment with R,R-tetrahydrochrysene. E3- and 3β-Adiol-mediated reduction in persistent Ca2+ signals is associated with ER-β-mediated attenuation of TPR expression and may partly explain estrogen benefits in coronary vascular muscle.
Blockade of MyD88 attenuates cardiac hypertrophy and decreases cardiac myocyte apoptosis in pressure overload-induced cardiac hypertrophy in vivo
Authors: Ha Tuanzhu , Hua Fang , Li Yuehua , Ma Jing , Gao Xiang , Kelley Jim , Zhao Aiqiu , Haddad Georges E. , Williams David L. , Browder I. William , Kao Race L. , Li Chuanfu
Published: September 2005

In this study, we evaluated whether blocking myeloid differentiation factor-88 (MyD88) could decrease cardiac myocyte apoptosis following pressure overload. Adenovirus expressing dominant negative MyD88 (Ad5-dnMyD88) or Ad5-green fluorescent protein (GFP) (Ad5-GFP) was transfected into rat hearts ( n = 8/group) immediately followed by aortic banding for 3 wk. One group of rats ( n = 8) was subjected to aortic banding for 3 wk without transfection. Sham surgical operation ( n = 8) served as control. The ratios of heart weight to body weight (HW/BW) and heart weight to tibia length (HW/TL) were calculated. Cardiomyocyte size was examined by FITC-labeled wheat germ agglutinin staining of membranes. Cardiac myocyte apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and myocardial interstitial fibrosis was examined by Masson's Trichrome staining. Aortic banding significantly increased the HW/BW by 41.0% (0.44 ± 0.013 vs. 0.31 ± 0.008), HW/TL by 47.2% (42.7 ± 1.30 vs. 29.0 ± 0.69), cardiac myocyte size by 49.6%, and cardiac myocyte apoptosis by 11.5%, and myocardial fibrosis and decreased cardiac function compared with sham controls. Transfection of Ad5-dnMyD88 significantly reduced the HW/BW by 18.2% (0.36 ± 0.006 vs. 0.44 ± 0.013) and HW/TL by 22.3% (33.2 ± 0.95 vs. 42.7 ± 1.30) and decreased cardiomyocyte size by 56.8%, cardiac myocyte apoptosis by 76.2%, as well as fibrosis, and improved cardiac function compared with aortic-banded group. Our results suggest that MyD88 is an important component in the Toll-like receptor-4-mediated nuclear factor-κB activation pathway that contributes to the development of cardiac hypertrophy. Blockade of MyD88 significantly reduced cardiac hypertrophy, cardiac myocyte apoptosis, and improved cardiac function in vivo.
Phospholemman overexpression inhibits Na+-K+-ATPase in adult rat cardiac myocytes: relevance to decreased Na+pump activity in postinfarction myocytes
Authors: Zhang Xue-Qian , Moorman J. Randall , Ahlers Belinda A. , Carl Lois L. , Lake Douglas E. , Song Jianliang , Mounsey J. Paul , Tucker Amy L. , Chan Yiu-mo , Rothblum Lawrence I. , Stahl Richard C. , Carey David J. , Cheung Joseph Y.
Published: September 2005

Messenger RNA levels of phospholemman (PLM), a member of the FXYD family of small single-span membrane proteins with putative ion-transport regulatory properties, were increased in postmyocardial infarction (MI) rat myocytes. We tested the hypothesis that the previously observed reduction in Na+-K+-ATPase activity in MI rat myocytes was due to PLM overexpression. In rat hearts harvested 3 and 7 days post-MI, PLM protein expression was increased by two- and fourfold, respectively. To simulate increased PLM expression post-MI, PLM was overexpressed in normal adult rat myocytes by adenovirus-mediated gene transfer. PLM overexpression did not affect the relative level of phosphorylation on serine68of PLM. Na+-K+-ATPase activity was measured as ouabain-sensitive Na+-K+pump current (Ip). Compared with control myocytes overexpressing green fluorescent protein alone, Ip measured in myocytes overexpressing PLM was significantly ( P < 0.0001) lower at similar membrane voltages, pipette Na+([Na+]pip) and extracellular K+([K+]o) concentrations. From −70 to +60 mV, neither [Na+]pipnor [K+]orequired to attain half-maximal Ip was significantly different between control and PLM myocytes. This phenotype of decreased Vmaxwithout appreciable changes in Kmfor Na+and K+in PLM-overexpressed myocytes was similar to that observed in MI rat myocytes. Inhibition of Ip by PLM overexpression was not due to decreased Na+-K+-ATPase expression because there were no changes in either protein or messenger RNA levels of either α1- or α2-isoforms of Na+-K+-ATPase. In native rat cardiac myocytes, PLM coimmunoprecipitated with α-subunits of Na+-K+-ATPase. Inhibition of Na+-K+-ATPase by PLM overexpression, in addition to previously reported decrease in Na+-K+-ATPase expression, may explain altered Vmaxbut not Kmof Na+-K+-ATPase in postinfarction rat myocytes.
Contraction-mediated phosphorylation of AMPK is lower in skeletal muscle of adenylate kinase-deficient mice
Authors: Hancock Chad R. , Janssen Edwin , Terjung Ronald L.
Published: September 2005

The activity of AMP-activated protein kinase (AMPK) increases during muscle contractions as a result of elevated AMP concentration. We tested whether activation of AMPK would be altered during contractions in adenylate kinase (AK) 1-deficient (AK1−/−) mice, because they have a reduced capacity to form AMP. The right gastrocnemius-soleus-plantaris muscle group was stimulated via the sciatic nerve at 2 Hz for 30 min in both wild-type (WT) and AK1−/−animals. Initial force production was not different between the two groups (129.2 ± 3.3 g vs. 140.9 ± 8.5 g for WT and AK1−/−, respectively); however, force production by AK1−/−mice was significantly greater over the 30-min stimulation period, and final tension was 85 ± 4.5% of initial in WT and 102 ± 3.2% of initial in AK1−/−mice. Western blot analysis showed that AMPK phosphorylation with contractions was clearly increased in WT muscles (4.0 ± 1.1 above resting values), but did not change noticeably with AK deficiency (1.6 ± 0.4 above WT resting values). However, increases in phosphorylation of acetyl CoA carboxylase were robust in both WT and AK1−/−muscles and not different between the two groups. These results suggest that reduced formation of AMP during contractions in skeletal muscle of AK1−/−mice results in reduced phosphorylation of AMPK. However, altered AMPK signaling was not apparent in the phosphorylation status of acetyl CoA carboxylase, a typical marker of AMPK activity.
Enhanced Conversion of Triglyceride-Rich Lipoproteins and Increased Low-Density Lipoprotein Removal in LPLS447X Carriers
Authors: Nierman Melchior C. , Prinsen Berthil H.C.M.T. , Rip Jaap , Veldman Robert Jan , Kuivenhoven Jan Albert , Kastelein John J.P. , de Sain-van der Velden Monique G.M. , Stroes Erik S.G.
Published: September 2005

Objective—

Lipoprotein lipase (LPL) exerts 2 principal actions, comprising enzymatic hydrolysis of triglyceride-rich lipoproteins (TRLs) and nonenzymatic ligand capacity for enhancing lipoprotein removal. The common LPLS447X variant has been associated with cardiovascular protection, for which the mechanism is unknown. We therefore evaluated enzymatic and nonenzymatic consequences of this LPL variant on TRL metabolism.

Methods and Results—

TRL apolipoprotein B100 (apoB100) metabolism was determined in 5 homozygous LPLS447X carriers and 5 controls. Subjects were continuously fed and received infusion of stable isotope
l
-[1-
13
C]-valine. Results were analyzed by SAAMII modeling. Also, preheparin and postheparin LPL concentration and activity were measured. Compared with controls, carriers presented increased very low–density lipoprotein 1 (VLDL
1
) to VLDL
2
apoB100 flux (
P
=0.04), increased VLDL
2
to intermediate-density lipoprotein (IDL) apoB100 flux (
P
=0.02), increased IDL to low-density lipoprotein (LDL) apoB100 flux (
P
=0.049), as well as an increased LDL clearance (
P
=0.04). Additionally, IDL apoB100 synthesis was attenuated (
P
=0.05). Preheparin LPL concentration was 4-fold higher compared with controls (
P
=0.01), and a correlation was observed between preheparin LPL concentration and LDL clearance (
r
2
=0.92;
P
=0.01).

Conclusions—

Enhanced TRL conversion and enhanced LDL removal combined with increased preheparin LPL concentration suggest increased enzymatic consequences as well as increased nonenzymatic consequences of LPL in LPLS447X carriers, which might both contribute to the cardiovascular benefit of this LPL variant.
Role of Focal Adhesion Kinase in Flow-Induced Dilation of Coronary Arterioles
Authors: Koshida Ryoji , Rocic Petra , Saito Shuichi , Kiyooka Takahiko , Zhang Cuihua , Chilian William M.
Published: September 2005

Backgound—

Flow-induced regulation of endothelial NO synthase (eNOS) depends on integrin signaling and tyrosine kinase activation. Integrins cluster in focal adhesion complexes, where the extracellular matrix is connected to the cytoskeleton and where focal adhesion kinase (FAK) is located. FAK plays a central role in integrin signaling and Src activation. Accordingly, we hypothesized that FAK plays an important role in flow-induced dilation (FID).

Methods and Results—

To inactivate FAK-dependent signaling, anti-FAK, phosphospecific (Tyr
397
) antibody (FAKab), which binds against the FAK autophosphorylation site, was incorporated into endothelium of rat coronary arterioles using liposomal transfection. The responses to flow, acetylcholine (Ach), or the NO donor MAHAMANONOate (NOC-9) were observed before and after FAKab. In control and vehicles (denatured antibody or transfecting reagent alone), flow produced progressive dilation to a maximal value of 35% increase in diameter, which was inhibited by
N
ω
-nitro-
l
-arginine methyl ester (
l
-NAME). However, FAKab prevented FID (
P
<0.01 versus control). Combined treatment with FAKab and
l
-NAME did not produce inhibition greater than FAKab alone. FAKab did not blunt Ach- or NOC-9–induced dilation. Western analysis demonstrated that FAKab prevented flow-induced phosphorylation of FAK (pY397-FAK), Akt (pS473-Akt), and eNOS (pS1179-eNOS).

Conclusion—

Our study demonstrates the pivotal role of FAK in NO-mediated FID. Inhibition of FAK signaling with FAKab impaired FID and phosphorylation of Akt and eNOS. Our data suggest that the activation of FAK is central to the mechanotransduction of FID via regulation of activation of Akt and eNOS.
Neck-Sealing in early Islam
Authors: Robinson Chase
Published: September 2005

Arabic and Syriac sources for early Islam, especially for seventh- and eighth-century Syria and Iraq, describe the use of neck sealings in the administration of the poll tax, which was levied upon non-Muslims. This article evaluates the relevant literary, historical and material evidence, including some surviving sealings, and proposes that at origin, neck-sealing related to other stigmatizing practices, and was principally symbolic and punitive. Des texts arabes et syriques, particulièrement originaires de la Syrie et de l'Iraq des septième et huitième siècles, décrivent l'usage des sceaux en pendentif pour l'application de la capitation qui était imposée aux non-musulmans. Cet article étudie les sources littéraires, historiques et archéologiques, y compris des sceaux qui nous restent, et suggère que à l'origine, les sceaux étaient liés à d'autres pratiques discriminatives/stigmatisantes, et étaient avant tout symboliques et punitives.
Climatological Features of Cutoff Low Systems in the Northern Hemisphere
Authors: Nieto Raquel , Gimeno Luis , de la Torre Laura , Ribera Pedro , Gallego David , García-Herrera Ricardo , García José Agustín , Nuñez Marcelino , Redaño Angel , Lorente Jerónimo
Published: September 2005

This study presents the first multidecadal climatology of cutoff low systems in the Northern Hemisphere. The climatology was constructed by using 41 yr (1958–98) of NCEP–NCAR reanalysis data and identifying cutoff lows by means of an objective method based on imposing the three main physical characteristics of the conceptual model of cutoff low (the 200-hPa geopotential minimum, cutoff circulation, and the specific structure of both equivalent thickness and thermal front parameter fields).

Several results were confirmed and climatologically validated: 1) the existence of three preferred areas of cutoff low occurrence (the first one extends through southern Europe and the eastern Atlantic coast, the second one is the eastern North Pacific, and the third one is the northern China–Siberian region extending to the northwestern Pacific coast; the European area is the most favored region); 2) the known seasonal cycle, with cutoff lows forming much more frequently in summer than in winter; 3) the short lifetime of cutoff lows, most cutoff lows lasted 2–3 days and very few lasted more than 5 days; and 4) the mobility of the system, with few cutoff lows being stationary. Furthermore, the long study period has made it possible (i) to find a bimodal distribution in the geographical density of cutoff lows for the European sector in all the seasons (with the exception of winter), a summer displacement to the ocean in the American region, and a summer extension to the continent in the Asian region, and (ii) to detect northward and westward motion especially in the transitions from the second to third day of occurrence and from the third to fourth day of occurrence.

The long-term cutoff low database built in this study is appropriate to study the interannual variability of cutoff low occurrence and the links between cutoff lows and jet stream systems, blocking, or major modes of climate variability as well as the global importance of cutoff low in the stratosphere–troposphere exchange mechanism, which will be the focus of a subsequent paper.
Role of Antecedent Land Surface Conditions on North American Monsoon Rainfall Variability*
Authors: Zhu Chunmei , Lettenmaier Dennis P. , Cavazos Tereza
Published: September 2005

Possible links between North American Monsoon System (NAMS) seasonal [June–July–August–September (JJAS)] precipitation and premonsoon seasonal land surface conditions including precipitation (P), surface air temperature (Ts), soil moisture (Sm), and snow water equivalent (SWE) anomalies are explored during the 1950–2000 period. A statistically significant inverse relationship is found between monsoon precipitation in an area defined as the Monsoon West (Arizona and western New Mexico) and antecedent winter precipitation in the southwestern (SW) United States and the mountainous region in Utah and Colorado (the predictor area). This linkage is strong during 1965–90 and weak otherwise, as has been suggested by previous studies. A land surface feedback hypothesis is proposed to explain this relationship: more winter P leads to more winter and early spring SWE in the predictor area, hence more spring and early summer Sm, and lower spring and early summer Ts, which induces a weaker onset (and less precipitation) of the NAMS and vice versa. All three links in this hypothesis were tested and the existence of a land memory associated with winter precipitation and snow, which can persist until June, was confirmed. However, the results show that this land memory contributes little to the magnitude of NAM precipitation. Winter snow is negatively correlated to late spring Ts in the SW mountainous region, but not in extreme years. In fact, the premonsoon (June) Ts over the U.S. southwest is inversely related to monsoon precipitation, which is the reverse of what is expected based on the hypothesis. The lack of a significant Sm–Ts–P relationship in most of the SW suggests, based on the constructed Sm dataset, that local premonsoon soil wetness conditions play a minor role in the strength of the monsoon. A strong positive relationship between June Ts anomalies and the large-scale midtropospheric circulation before the onset of the monsoon was found, suggesting that the controlling factor for the premonsoon Ts anomalies may not be local (i.e., not from the land surface). The results suggest that further research is needed to elucidate the nature of land–sea–atmosphere interactions as related to the onset of the monsoon.
Investigation of Hydrological Variability in West Africa Using Land Surface Models
Authors: Li K. Y. , Coe M. T. , Ramankutty N.
Published: September 2005

The availability of freshwater is a particularly important issue in Africa where large portions of the continent are arid or semiarid and climate is highly variable. Sustainable water resource management requires the assessment of hydrological variability in response to nature climate fluctuation. In this study, a land surface model, the Integrated Biosphere Simulator (IBIS), and a hydrological routing model, the Hydrological Routing Algorithm (HYDRA), are used to investigate the hydrological variability in two large basins, the Lake Chad basin (LCB) and the Niger River basin (NRB), located in West Africa, over the period from 1950 to 1995. The IBIS land surface hydrological module was calibrated and validated for arid and semiarid Africa, and major enhancements were made to the module, including the development of a dynamic root water–extraction formulation, the incorporation of a Green–Ampt infiltration parameterization, and modification to the prescribed root distribution, the runoff module, and weather generator. The results show that the hydrology in this area is highly variable over time and space. The coefficient of variance (CV) of annual rainfall ranges from 10%–15% in the southern portions of the basins to 30%–40% in the northern portions. The annual evapotranspiration (ET) varies with a slightly lower CV compared to the rainfall, but the runoff is extremely sensitive to the rainfall fluctuation, particularly in the central portions of the basins (8°–13°N in LCB and 12°–16°N in NRB) where the CVs in runoff are as high as 100%–200%. The annual river discharge varies largely in concert with the rainfall fluctuation, with the CV being 37% in LCB and 23%–63% in NRB. In terms of the whole basin, the relative hydrologic variability (rainfall, evapotranspiration, runoff, and river discharge) is significantly higher in the dry period than in the wet period, and the interannual variability in runoff is more than twice as high as compared to rainfall or ET.
The Sensitivity of the Tropical-Mean Radiation Budget
Authors: Clement Amy C. , Soden Brian
Published: September 2005

A key disagreement exists between global climate model (GCM) simulations and satellite observations of the decadal variability in the tropical-mean radiation budget. Measurements from the Earth Radiation Budget Experiment (ERBE) over the period 1984–2001 indicate a trend of increasing longwave emission and decreasing shortwave reflection that no GCM can currently reproduce. Motivated by these results, a series of model sensitivity experiments is performed to investigate hypotheses that have been advanced to explain this discrepancy. Specifically, the extent to which a strengthening of the Hadley circulation or a change in convective precipitation efficiency can alter the tropical-mean radiation budget is assessed. Results from both model sensitivity experiments and an empirical analysis of ERBE observations suggest that the tropical-mean radiation budget is remarkably insensitive to changes in the tropical circulation. The empirical estimate suggests that it would require at least a doubling in strength of the Hadley circulation in order to generate the observed decadal radiative flux changes. In contrast, rather small changes in a model’s convective precipitation efficiency can generate changes comparable to those observed, provided that the precipitation efficiency lies near the upper end of its possible range. If, however, the precipitation efficiency of tropical convective systems is more moderate, the model experiments suggest that the climate would be rather insensitive to changes in its value. Further observations are necessary to constrain the potential effects of microphysics on the top-of-atmosphere radiation budget.
Statistical Modeling in Nonlinear Systems
Authors: Campbell Edward P.
Published: September 2005

The use of linear statistical methods in building climate prediction models is examined, particularly the use of anomalies. The author’s perspective is that the climate system is a nonlinear interacting system, so the impact of modeling using anomalies rather than observed data directly is considered. With reference to the Lorenz system and a simple model for regime dependence, it is shown that anomalies impair our ability to reconstruct nonlinear dynamics. Some alternative approaches in the literature that offer an attractive way forward are explored, focusing on Bayesian hierarchical methods to construct so-called physical–statistical models. The author’s view is that anomalies should be reserved in most cases as a tool for enhancing graphical representations of climate data. The exceptions are when the implicit assumptions underlying the use of anomalies are met or when an anomaly representation is physically motivated.
A Closer Comparison of Early and Late-Winter Atmospheric Trends in the Northern Hemisphere
Authors: Hu Yongyun , Tung Ka Kit , Liu Jiping
Published: September 2005

Decadal trends are compared in various fields between Northern Hemisphere early winter, November–December (ND), and late-winter, February–March (FM), months using reanalysis data. It is found that in the extratropics and polar region the decadal trends display nearly opposite tendencies between ND and FM during the period from 1979 to 2003. Dynamical trends in late winter (FM) reveal that the polar vortex has become stronger and much colder and wave fluxes from the troposphere to the stratosphere are weaker, consistent with the positive trend of the Arctic Oscillation (AO) as found in earlier studies, while trends in ND appear to resemble a trend toward the low-index polarity of the AO. In the Tropics, the Hadley circulation shows significant intensification in both ND and FM, with stronger intensification in FM. Unlike the Hadley cell, the Ferrel cell shows opposite trends between ND and FM, with weakening in ND and strengthening in FM. Comparison of the observational results with general circulation model simulations is also discussed.
Relationships between South Atlantic SST Variability and Atmospheric Circulation over the South African Region during Austral Winter
Authors: Reason C. J. C. , Jagadheesha D.
Published: September 2005

The Southwestern Cape (SWC) region of South Africa is characterized by winter rainfall brought mainly via cold fronts and by substantial interannual variability. Previous work has found evidence that the interannual variability in SWC winter rainfall may be related to sea surface temperature (SST) in the South Atlantic Ocean and to large-scale ocean–atmosphere interaction in this region. During wet winters, SST tends to be anomalously warm (cool) in the southwest Atlantic and southeast Atlantic (central South Atlantic). Atmospheric general circulation model experiments with various idealized SST anomalies in the South Atlantic are used to explore mechanisms potentially associated with the rainfall variability. The model results suggest that the atmosphere is sensitive to subtropical–midlatitude SST anomalies in the South Atlantic during winter. Locally, there are changes to the jet position and strength, low-level relative vorticity, and convergence of moisture and latent heat flux that lead to changes in rainfall over the SWC. The model response to the SST forcing also shows large-scale anomalies in the midlatitude Southern Hemisphere circulation, namely, an Antarctic Oscillation–type mode and wavenumber-3 changes, similar to those observed during anomalous winters in the region.
LGM Summer Climate on the Southern Margin of the Laurentide Ice Sheet: Wet or Dry?*
Authors: Bromwich David H. , Toracinta E. Richard , Oglesby Robert J. , Fastook James L. , Hughes Terence J.
Published: September 2005

Regional climate simulations are conducted using the Polar fifth-generation Pennsylvania State University (PSU)–NCAR Mesoscale Model (MM5) with a 60-km horizontal resolution domain over North America to explore the summer climate of the Last Glacial Maximum (LGM: 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level.

The simulated LGM summer climate is characterized by a pronounced low-level thermal gradient along the southern margin of the LIS resulting from the juxtaposition of the cold ice sheet and adjacent warm ice-free land surface. This sharp thermal gradient anchors the midtropospheric jet stream and facilitates the development of synoptic cyclones that track over the ice sheet, some of which produce copious liquid precipitation along and south of the LIS terminus. Precipitation on the southern margin is orographically enhanced as moist southerly low-level flow (resembling a contemporary Great Plains low-level jet configuration) in advance of the cyclone is drawn up the ice sheet slope. Composites of wet and dry periods on the LIS southern margin illustrate two distinctly different atmospheric flow regimes. Given the episodic nature of the summer rain events, it may be possible to reconcile the model depiction of wet conditions on the LIS southern margin during the LGM summer with the widely accepted interpretation of aridity across the Great Plains based on geological proxy evidence.
Adverse-Weather Trends in the Canadian Arctic
Authors: Hanesiak John M. , Wang Xiaolan L.
Published: September 2005

This study provides an assessment of changes in the occurrence frequency of four types of adverse-weather (freezing precipitation, blowing snow, fog, and low ceilings) and no-weather (i.e., no precipitation or visibility obscuration) events as observed at 15 Canadian Arctic stations of good hourly weather observations for 1953–2004. The frequency time series were subjected to a homogenization procedure prior to a logistic regression–based trend analysis.

The results show that the frequency of freezing precipitation has increased almost everywhere across the Canadian Arctic since 1953. Rising air temperature in the region has probably resulted in more times that the temperature is suitable for freezing precipitation. On the contrary, the frequency of blowing snow occurrence has decreased significantly in the Canadian Arctic. The decline is most significant in spring. Changes in fog and low ceiling (LC) occurrences have similar patterns and are most (least) significant in summer (autumn). Decreases were identified for both types of events in the eastern region in all seasons. In the southwest, however, the fog frequency has increased significantly in all seasons, while the LC frequency has decreased significantly in spring and summer. The regional mean rate of change in the frequency of the four types of adverse weather was estimated to be 7%–13% per decade.

The frequency of no-weather events has also decreased significantly at most of the 15 sites. The decrease is most significant and extensive in autumn. Comparison with the adverse-weather trends above indicates that the decline in no-weather occurrence (i.e., increase in weather occurrence) is not the result of an increase in blowing snow or fog occurrence; it is largely the result of the increasing frequency of freezing precipitation and, most likely, other types of precipitation as well. This is consistent with the reported increases in precipitation amount and more frequent cyclone activity in the lower Canadian Arctic.
A longitudinal study of the influence of shop floor work teams on expressions of ‘us’ and ‘them’
Authors: Coupland Christine , Blyton Paul , Bacon Nicholas
Published: September 2005

A discourse analysis of employee rhetoric before and after the introduction of shop floor work teams in a steel mill reveals important changes in expressions of ‘us’ and ‘them’ attitudes. The normative rhetoric of teamworking used by managers, insisting that all employees are working towards the same goal, raised an expectation of change in the traditional ‘them’ and ‘us’ divide between managers and workers. When workers detected little subsequent change they used the new language of teamworking to critique management in private although working in teams they reported pressure to behave differently. New working roles in teams did undermine traditional ‘them’ and ‘us’ loyalties, which fragmented to encompass finer distinctions (e.g. middle and upper management, workers and slackers) and employee attitudes became more individualistic.
Seeing soil carbon: use of thermal analysis in the characterization of soil C reservoirs of differing stability
Authors: Manning D. A. C. , Lopez-Capel E. , Barker S.
Published: September 2005

To understand the rates of turnover of soil carbon, and hence interactions between soil carbon pools and atmospheric CO2 levels, it is essential to be able to quantify and characterize soil organic matter and mineral hosts for C. Thermal analysis is uniquely suited to this task, as different C compounds decompose during a heating cycle at different temperatures. In ‘air’ (80% He or N2, 20% O2), relatively labile cellulosic material decomposes between 300 and 350°C and more refractory lignin and related materials decompose between 400 and 650°C. Calcite and other common soil carbonate minerals decompose at 750–900°C. Using thermal analysis connected to a quadrupole mass spectrometer and to an isotope ratio mass spectrometer, it is possible to simultaneously determine mass loss during combustion, evolved gas molecular compositions, and carbon isotope ratios for evolved CO2. As an example of the potential of the technique, the evolution of a fungally-degraded wheat straw shows initial isotopic heterogeneity consistent with its plant origins (–23.8% v-PDB for cellulosic material; –26.1% v-PDB for ligninic material), which homogenizes at heavier δ13C values (–21.0% v-PDB) as lignin is preferentially degraded by fungal growth. Simultaneously, it is shown that the evolution of nitrogen compounds is initially dominated by decomposition of aliphatic N within the cellulosic component, but that with increasing fungal degradation it is the ligninic component that contributes N to evolved gases, derived presumably from pyrrolic and related N groups produced during soil degradation through condensation reactions. Overall, the use of thermal analysis coupled to quadrupole and stable isotope mass spectrometry appears to have considerable potential for the characterization of discrete carbon pools that are amenable to the modelling of carbon turnover within soil systems.
Behaviour of impurity elements during the weathering of ilmenite
Authors: Grey I. , MacRae C. , Silvester E. , Susini J.
Published: September 2005

X-ray spectromicroscopy has been applied to the characterization of weathered ilmenite sand samples from Australian localities. X-ray absorption near edge spectroscopy (Xanes) studies were performed at the K-edges of the major elements Fe and Ti and minor impurity elements Mn and Cr. An extended suite of reference samples with crystallite sizes ranging from 1 nm to μm size were measured to establish if the absorption edge characteristics were influenced by crystal size effects. No changes were detected for oxides of Cr3+, Fe3+ or Ti4+, but the mixed Fe2+/Fe3+ oxide, Fe3O4, showed an edge shift to higher energies (by 1.5 eV) in a nanocrystalline sample. The Xanes study of a composite ilmenite grain with an unweathered primary ilmenite core and a highly weathered rim showed that Fe was present as Fe2+ in the core and Fe3+ in the rim whereas Mn was present as Mn2+ in both core and rim. Chromium, which is incorporated into the grains during weathering, is present predominantly as Cr3+, although minor (~15%) Cr6+ also occurs in highly weathered grains. The absorption K-edges of Fe3+ and Mn2+ are shifted markedly (by 2–3 eV) to higher energies in titanate phases relative to the binary oxides Fe2O3 and MnO.
Two-dimensional natural pyrite crystals and their formation
Authors: Sawlowicz Z. , Łatkiewicz A. , Stefaniak E.
Published: September 2005

Two-dimensional pyrite crystals (40–80 µm wide and 2–3 µm thick) and large thin crusts are reported from the mudstones from the Carboniferous coal basin in Poland. Crystals occur on a flat surface, originally probably a crack in the rock, and are composed of uniform particles (150–200 nm wide). A hypothetical pathway of the formation of 2D pyrite crystals is presented: (1) formation of pyrite particles (or monosulphide precursors) in the suspension introduced onto the surface of the crack, and forming a film with a smooth meniscus at the air/suspension interface on the rock substrate; (2) thinning of the suspension film due to the water loss, increase of particle concentration, and formation of the first monolayers; (3) growth leading to the formation of thin crystals complying with pyrite crystallography.
Deformation-controlled cation diffusion in compositionally zoned tourmaline
Authors: Büttner S. H.
Published: September 2005

The compositional zonation of both undeformed and plastically deformed tourmaline crystals from an amphibolite-facies mylonitic pegmatite from the Sierras Pampeanas (NW Argentina) has been investigated using electron microprobe analysis (EMPA). Undeformed tourmaline shows optical and compositional major and minor element growth zonation with a Ca- and Mg-rich rim zone and an Fe- rich core zone. The tourmaline population of the mylonite consists of crystals which appear undeformed at microscopic scale, and of weakly, moderately, and strongly deformed crystals. Depending on the intensity of plastic deformation, the optical zonation is blurred or absent, and the compositional zonation is less pronounced or destroyed. Plastic deformation mobilizes small cations (Fe2+, Mg2+) more efficiently and at lower deformation intensity than larger cations (Na+, Ca2+). In addition to intra-crystal homogenization, plastic deformation caused variable but generally minor Fe, Mg, Si, Al, Ca, and Na exchange between deformed tourmaline domains and co-existing fluid or solid phases. Dislocation creep is interpreted as the dominant deformation mechanism leading to the homogenization of the initial tourmaline growth zonation. The composition and the degree of homogeneity of deformed tourmaline domains depend on the initial composition of the growth zones, their initial volume ratio, the intensity and homogeneity of plastic deformation, and the size of the mobilized cation. Consequently, the composition of and the element distribution within plastically deformed crystals is not entirely controlled by intensive variables (P-T-X), and therefore not suitable for petrogenetic interpretation.
Growth ordering and anomalous birefringence in ugrandite garnets
Authors: Shtukenberg A. G. , Popov D. Yu. , Punin Yu. O.
Published: September 2005

Intermediate members of the grossular–andradite and grossular–uvarovite series are known to display anomalous birefringence, which is inconsistent with the ideal cubic space group of garnetIad. To determine the reason for such birefringence, the crystal structures of at least 15 samples were refined by different authors including the present ones. The crystals with the value of anomalous birefringence of Δn> 0.001 are normally characterized by partial ordering of the octahedral cations (Al/Fe and Al/Cr for grossular–andradite and grossular–uvarovite series, respectively). This reduces the symmetry to the orthorhombic space groupFdddor even to the triclinic space groupI. As is seen from the distribution of occupancies over octahedral sites in the triclinic space group, eight occupancies are grouped into two quartets of similar occupancies, leading to pseudo-orthorhombic crystal structures. The variety of structures with different degrees of pseudo-orthorhombicity is due to the action of the growth dissymmetrization mechanism. Simulations of the optical indicatrix in the point-dipole approximation confirm cation ordering as the main cause of the anomalous birefringence.
Expression of Pitx2 in stromal cells is required for normal hematopoiesis
Authors: Kieusseian Aurélie , Chagraoui Jalila , Kerdudo Cécile , Mangeot Philippe-Emmanuel , Gage Philip J. , Navarro Nicole , Izac Brigitte , Uzan Georges , Forget Bernard G. , Dubart-Kupperschmitt Anne
Published: September 2005

Although the expression of Pitx2, a bicoid family homeodomain transcription factor, is highly regulated during hematopoiesis, its function during this process was not documented; we thus studied hematopoiesis in Pitx2-null mice. We found that Pitx2–/– embryos display hypoplastic livers with reduced numbers of hematopoietic cells, but these cells had normal hematopoietic potential, as evidenced by colony-forming assays, immature progenitor cell assays, and long-term repopulation assays. Because the microenvironment is also crucial to the development of normal hematopoiesis, we established Pitx2–/– and Pitx2+/+ stromas from fetal liver and studied their hematopoietic supportive capacity. We showed that the frequency of cobblestone area-forming cells was 4-fold decreased when using Pitx2–/– stromal cells compared with Pitx2+/+ stromal cells, whatever the Pitx2 genotype of hematopoietic cells tested in this assay. This defect was rescued by expression of Pitx2 into Pitx2–/– fetal liver stromal cells, demonstrating a major and direct role of Pitx2 in the hematopoietic supportive capacity of fetal liver stroma. Finally, we showed a reduced capacity of MS5 stromal cells expressing Pitx2 RNAi to support human hematopoiesis. Altogether these data showed that Pitx2 has major functions in the hematopoietic supportive capacity of fetal liver and adult bone marrow stromal cells.
C1qTNF–related protein-1 (CTRP-1): a vascular wall protein that inhibits collagen-induced platelet aggregation by blocking VWF binding to collagen
Authors: Lasser Gerald , Guchhait Prasenjit , Ellsworth Jeff L. , Sheppard Paul , Lewis Ken , Bishop Paul , Cruz Miguel A. , Lopez Jose A. , Fruebis Joachim
Published: September 2005

CTRP-1 is a novel member of the C1qTNF–related protein family containing family characteristic collagen and TNF-like domains and shows marked expression in vascular wall tissue. We observed that recombinant human CTRP-1 specifically bound to fibrillar collagen and blocked collagen-induced platelet aggregation. CTRP-1 completely or partially prevented VWF and GPVI-Fc4 binding to collagen, respectively. However, GPVI-Fc4 failed to compete for the binding of CTRP-1 to collagen. CTRP-1 had no effects on α2β1 integrin I–domain binding to collagen. Using whole human blood under flow at low and high shear rates, CTRP-1 prevented platelets from accumulating on a collagen-coated surface but had no effects on “platelet-rolling” on a surface coated with VWF. These data suggest that CTRP-1 prevents collagen-induced platelet aggregation by specific blockade of VWF binding to collagen. By using the Folts vascular injury model in nonhuman primates (Macaca fascicularis), we were able to demonstrate that CTRP-1 can prevent platelet thrombosis in vivo. This effect was achieved in the absence of changes in activated-clotting time (ACT) and template cut bleeding times, suggesting that CTRP-1 has promising antiplatelet thrombotic activity and most likely acts by pacifying the thrombogenic site of vascular injury.
Coordination between NF-κB family members p50 and p52 is essential for mediating LTβR signals in the development and organization of secondary lymphoid tissues
Authors: Lo James C. , Basak Soumen , James Ethan S. , Quiambo Raechel S. , Kinsella Marcus C. , Alegre Maria-Luisa , Weih Falk , Franzoso Guido , Hoffmann Alexander , Fu Yang-Xin
Published: September 2005

Recent studies revealed that the lymphotoxin/lymphotoxin beta receptor (LT)/LTβR system activates the noncanonical nuclear factor-κB (NF-κB) signaling pathway involving I kappa B kinase 1/I kappa B kinase α (IKK1/IKKα) and NF-κB-inducing kinase (NIK) to direct processing of the nfκb2 protein p100 to yield RelB:p52 complexes. Despite the biochemical evidence, LT-, RelB-, p52-deficient mice show discrepant phenotypes. We now demonstrate that p105/p50 also constitutes an important pathway for LTβR signaling. Our studies revealed that mice deficient in either p50 or p52 have defects in the formation of inguinal lymph nodes (LNs), but that the complete defect in lymph node formation and splenic microarchitecture seen in LT-deficient mice is recapitulated only in mice deficient in both p50 and p52. Biochemically, we find not only that both p50- and p52-containing NF-κB activities are induced by LTβR signaling, but that the induction of NF-κB-containing complexes by LTβR engagement is perturbed in single knockouts. Importantly, the LTβR can additionally activate the less well-characterized p52:RelA and p50:RelB pathways, which play pivotal roles in vivo for the development and organization of lymphoid structures. Our genetic, cellular, and molecular evidence points toward a model of LT-mediated NF-κB regulation in which p105/p50 and p100/p52 have distinct and coordinating molecular specificities but differ in the upstream signaling pathways that regulate them.
Induction of lymphatic endothelial cell differentiation in embryoid bodies
Authors: Liersch Ruediger , Nay Filip , Lu Lingge , Detmar Michael
Published: September 2005

The molecular mechanisms that regulate the formation of the lymphatic vascular system remain poorly characterized. Whereas studies in embryonic stem (ES) cells have provided major new insights into the mechanisms of blood vessel formation, the development of lymphatic endothelium has not been previously observed. We established embryoid bodies (EBs) from murine ES cells in the presence or absence of lymphangiogenic growth factors. We found that lymphatic endothelial cells develop at day 18 after EB formation. These cells express CD31 and the lymphatic lineage markers Prox-1 and Lyve-1, but not the vascular marker MECA-32, and they frequently sprout from preexisting blood vessels. Lymphatic vessel formation was potently promoted by VEGF-A and VEGF-C but not by bFGF. Our results reveal, for the first time, that ES cells can differentiate into lymphatic endothelial cells, and they identify the EB assay as a powerful new tool to dissect the molecular mechanisms that control lymphatic vessel formation.
Biochemical characterization of Cdk2-Speedy/Ringo A2
Authors: Cheng Aiyang , Gerry Shannon , Kaldis Philipp , Solomon Mark J
Published: September 2005

Background

Normal cell cycle progression requires the precise activation and inactivation of cyclin-dependent protein kinases (CDKs), which consist of a CDK and a cyclin subunit. A novel cell cycle regulator called Speedy/Ringo shows no sequence similarity to cyclins, yet can directly bind to and activate CDKs. Speedy/Ringo proteins, which bind to and activate Cdc2 and Cdk2 in vitro, are required for the G2 to M transition during Xenopus oocyte maturation and for normal S-phase entry in cultured human cells.

Results

We have characterized the substrate specificity and enzymatic activity of human Cdk2-Speedy/Ringo A2 in order to gain insights into the possible functions of this complex. In contrast to Cdk2-cyclin A, which has a well-defined consensus target site ((S/T)PX(K/R)) that strongly favors substrates containing a lysine at the +3 position of substrates, Cdk2-Speedy/Ringo A2 displayed a broad substrate specificity at this position. Consequently, Cdk2-Ringo/Speedy A2 phosphorylated optimal Cdk2 substrates such as histone H1 and a KSPRK peptide poorly, only ~0.08% as well as Cdk2-cyclin A, but non-canonical Cdk2 substrates such as a KSPRY peptide relatively well, with an efficiency of ~80% compared to Cdk2-cyclin A. Cdk2-Speedy/Ringo A2 also phosphorylated authentic Cdk2 substrates, such as Cdc25 proteins, which contain non-canonical CDK phosphorylation sites, nearly as well as Cdk2-cyclin A. Phosphopeptide mapping indicated that Cdk2-Speedy/Ringo A2 and Cdk2-cyclin A phosphorylate distinct subsets of sites on Cdc25 proteins. Thus, the low activity that Cdk2-Speedy/Ringo A2 displays when assayed on conventional Cdk2 substrates may significantly underestimate the potential physiological importance of Cdk2-Speedy/Ringo A2 in phosphorylating key subsets of Cdk2 substrates. Unlike Cdk2-cyclin A, whose activity depends strongly on activating phosphorylation of Cdk2 on Thr-160, neither the overall catalytic activity nor the substrate recognition by Cdk2-Speedy/Ringo A2 was significantly affected by this phosphorylation. Furthermore, Cdk2-Speedy/Ringo A2 was not a suitable substrate for metazoan CAK (which phosphorylates Cdk2 at Thr-160), supporting the notion that Speedy/Ringo A2 activates Cdk2 in a CAK-independent manner.

Conclusion

There are major differences in substrate preferences between CDK-Speedy/Ringo A2 and Cdk2-cyclin complexes. These differences may accommodate the CAK-independent activation of Cdk2 by Speedy/Ringo A2 and they raise the possibility that CDK-Speedy/Ringo A2 complexes could phosphorylate and regulate a subset of non-canonical CDK substrates, such as Cdc25 protein phosphatases, to control cell cycle progression.