bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of cancer cachexia on triacylglycerol/fatty acid substrate cycling in white adipose tissue
Authors: Beck S. A. , Tisdale M. J.
Published: November 2006

The effect of cancer cachexia on the TAG/FA substrate cycle in white adipose tissue was determined in vivo using the MAC16 murine model of cachexia. When compared with non‐tumor‐bearing animals, the rate of TAG‐glycerol production was found to be increased almost threefold in animals bearing the MAC13 tumor, which does not induce cachexia, but was not further elevated in animals bearing the MAC16 tumor. In both cases TAG‐glycerol production and de novo synthesis of TAG‐FA were also increased above non‐tumor‐bearing animals. In animals bearing the MAC16 tumor, the TAG‐FA rates were significantly higher than in animals bearing the MAC13 tumor. This suggests that the presence of the tumor alone is sufficient to cause an increase in cycling rate, and in the absence of an elevated energy intake (MAC16) this may contribute to the depletion of adipose tissue.
Modifying milk fat composition of dairy cows to enhance fatty acids beneficial to human health
Authors: Lock Adam L. , Bauman Dale E.
Published: November 2006

There is increased consumer awareness that foods contain microcomponents that may have beneficial effects on health maintenance and disease prevention. In milk fat these functional food components include EPA, DHA, and CLA. The opportunity to enhance the content of these FA in milk has improved as a result of recent advances that have better defined the interrelationships between rumen fermentation, lipid metabolism, and milk fat synthesis. Dietary lipids undergo extensive hydrolysis and biohydrogenation in the rumen. Milk fat is predominantly TG, and de novo FA synthesis and the uptake of circulating FA contribute nearly equal amounts (molar basis) to the FA in milk fat. Transfer of dietary EPA and DHA to milk fat is very low (<4%); this is, to a large extent, related to their extensive biohydrogenation in the rumen, and also partly due to the fact that they are not transported in the plasma lipid fractions that serve as major mammary sources of FA uptake (TG and nonesterified FA). Milk contains over 20 isomers of CLA but the predominant one is cis‐9,trans‐11 (75–90% of total CLA). Biomedical studies with animal models have shown that this isomer has anticarcinogenic and anti‐atherogenic activities. cis‐9,trans‐11‐CLA is produced as an intermediate in the rumen biohydrogenation of linoleic acid but not of linolenic acid. However, it is only a transient intermediate, and the major source of milk fat CLA is from endogenous synthesis. Vaccenic acid, produced as a rumen biohydrogenation intermediate from both linoleic acid and linolenic acid, is the substrate, and Δ9‐desaturase in the mammary gland and other tissues catalyzes the reaction. Diet can markedly affect milk fat CLA content, and there are also substantial differences among individual cows. Thus, strategies to enhance milk fat CLA involve increasing rumen outflow of vaccenic acid and increasing Δ9‐desaturase activity, and through these, several‐fold increases in the content of CLA in milk fat can be routinely achieved. Overall, concentrations of CLA, and to a lesser extent EPA and DHA, can be significantly enhanced through the use of diet formulation and nutritional management of dairy cows.
Long‐chain polyunsaturated fatty acids in childhood developmental and psychiatric disorders
Authors: Richardson Alexandra J.
Published: November 2006

Both omega‐3 and omega‐6 long‐chain PUFA (LC‐PUFA) are crucial to brain development and function, but omega‐3 LC‐PUFA in particular are often lacking in modern diets in developed countries. Increasing evidence, reviewed here, indicates that LC‐PUFA deficiencies or imbalances are associated with childhood developmental and psychiatric disorders including ADHD, dyslexia, dyspraxia, and autistic spectrum disorders. These conditions show a high clinical overlap and run in the same families, as well as showing associations with various adult psychiatric disorders in which FA abnormalities are already implicated, such as depression, other mood disorders, and schizophrenia. Preliminary evidence from controlled trials also suggests that dietary supplementation with LC‐PUFA might help in the management of these kinds of childhood behavioral and learning difficulties. Treatment with omega‐3 FA appears most promising, but the few small studies published to date have involved different populations, study designs, treatments, and outcome measures. Largescale studies are now needed to confirm the benefits reported. Further research is also required to assess the durability of such treatment effects, to determine optimal treatment compositions and dosages, and to develop reliable ways of identifying those individuals most likely to benefit from this kind of treatment. Childhood developmental and psychiatric disorders clearly reflect multifactorial influences, but the study of LC‐PUFA and their metabolism could offer important new approaches to their early identification and management. Heterogeneity and comorbidity are such, however, that a focus on specific traits or symptoms may prove more fruitful than an exclusive reliance on current diagnostic categories.
Hypochlorous acid scavenging properties of local mediterranean plant foods
Authors: Schaffer Sebastian , Eckert Gunter P. , Müller Walter E. , Llorach Rafael , Rivera Diego , Grande Simona , Galli Claudio , Visioli Francesco
Published: November 2006

Oxidative modification of low density lipoprotein (LDL) is involved in the pathogenesis of atherosclerosis and coronary heart disease, which are low in the Mediterranean area possibly due to a high dietary proportion of plant food. Ethanolic extracts were prepared from more than 120 Mediterranean edible plants collected in remote areas (which maintain their tradional diet) and their antioxidant potential was studied. Extracts derived from Agaricus campestris, Cyana cardunculus, Thymus pulegioides, and Vicia faba were subjected to further analysis in this study. The extracts' potential to scavenge the DPPH radical (2,2‐diphenyl‐1‐picrylhydrazyl radical) and hypochlorous acid (HOCl), as well as their antioxidant capacity, was comparable to the those obtained for standard antioxidants (e.g., quercetin, Trolox), Myeloperoxidase (MPO) catalyzes the production of the highly chlorinating and oxidizing agent HOCl, which reacts with the LDL apoprotein moiety, leading to the derivatization of its aminoacidic residues. Coincubation with extracts significantly prevented HOCl‐induced modification of the LDL residue tryptophan, whereas higher concentrations were required to retard lysine damage. Moreover, the extracts inhibited MPO‐catalyzed guaiacol oxidation in a concentration‐dependent manner in a cell‐free assay but, in contrast, did not affect MPO activity in isolated human neutrophils. MPO is also known to facilitate nitric dioxide oxidation. The formation of 3‐nitrotyrosine was significantly lower in bovine endothelial aortic cells incubated with C. cardunculus or T. pulegioides. In synthesis, our study shows that local Mediterranean plant foods prevent HOCI toxicity in vitro and, thus suggests further mechanisms responsible for the reported health‐beneficial effect of the Mediterranean diet.
Structure determinants and substrate recognition of serine carboxypeptidase‐like acyltransferases from plant secondary metabolism
Authors: Stehle Felix , Brandt Wolfgang , Milkowski Carsten , Strack Dieter
Published: November 2006

Structures of the serine carboxypeptidase‐like enzymes 1‐O‐sinapoyl‐β‐glucose:l‐malate sinapoyltransferase (SMT) and 1‐O‐sinapoyl‐β‐glucose:choline sinapoyltransferase (SCT) were modeled to gain insight into determinants of specificity and substrate recognition. The structures reveal the α/β‐hydrolase fold as scaffold for the catalytic triad Ser‐His‐Asp. The recombinant mutants of SMT Ser173Ala and His411Ala were inactive, whereas Asp358Ala displayed residual activity of 20%. 1‐O‐sinapoyl‐β‐glucose recognition is mediated by a network of hydrogen bonds. The glucose moiety is recognized by a hydrogen bond network including Trp71, Asn73, Glu87 and Asp172. The conserved Asp172 at the sequence position preceding the catalytic serine meets sterical requirements for the glucose moiety. The mutant Asn73Ala with a residual activity of 13% underscores the importance of the intact hydrogen bond network. Arg322 is of key importance by hydrogen bonding of 1‐O‐sinapoyl‐β‐glucose and l‐malate. By conformational change, Arg322 transfers l‐malate to a position favoring its activation by His411. Accordingly, the mutant Arg322Glu showed 1% residual activity. Glu215 and Arg219 establish hydrogen bonds with the sinapoyl moiety. The backbone amide hydrogens of Gly75 and Tyr174 were shown to form the oxyanion hole, stabilizing the transition state. SCT reveals also the catalytic triad and a hydrogen bond network for 1‐O‐sinapoyl‐β‐glucose recognition, but Glu274, Glu447, Thr445 and Cys281 are crucial for positioning of choline.
Altered β‐secretase enzyme kinetics and levels of both BACE1 and BACE2 in the Alzheimer's disease brain
Authors: Stockley John H. , Ravid Rivka , O’Neill Cora
Published: November 2006

β‐Secretase is the rate limiting enzymatic activity in the production of amyloid‐β peptide, the primary component of senile plaque pathology in Alzheimer's disease (AD). This study performed the first comparative analysis of β‐secretase enzyme kinetics in AD and control brain tissue. Results found V
max values for β‐secretase to be significantly increased, and K
m values unchanged in AD temporal cortex compared to matched control temporal cortex. The increased V
max in AD cases, did not correlate with levels of BACE1, and decreased BACE1 and BACE2 levels correlated with the severity of neurofibrillary pathology (I–VI), and synaptic loss in AD. These results indicate that increased V
max for β‐secretase is a feature of AD pathogenesis and this increase does not correlate directly with levels of BACE1, the principal β‐secretase in brain.
Rotational Alignment of the Finger Nails in a Normal Population
Authors: BANSAL R. , CRAIGEN M. A. C.
Published: November 2006

We measured the alignment of the nails in the hands of 100 normal adults with the interphalangeal joints extended and the metacarpophalangeal (MCP) joints at 0° and 90°. All fingers were naturally supinated (i.e. rotated towards the thumb), the index and little being the most supinated. When examining individual hands in MCP joint extension, only 17% of hands had all nails parallel. With the MCP joints flexed, this improved to 56%. If the little finger was excluded, this improved to 78%. When comparing matching fingers from the two hands, 76% of little, 83% of ring, 77% of middle and 80% of index fingers matched. Thumbnails were assessed in extension and found to match the other side in 95% of individuals. This study identifies that examination of the injured hand alone with all joints extended is an unreliable method of assessing malrotation following fracture, especially in the little finger. Comparing matching fingers in the two hands is more reliable, but there is still substantial variation in approximately 20% of normal individuals.
Water precautions and ear surgery: evidence and practice in the UK
Authors: Basu S , Georgalas C , Sen P , Bhattacharyya A K
Published: November 2006

Background: Patients are traditionally advised to refrain from exposing their ears to water after most otological procedures. However, recent evidence suggests that water does not adversely affect the outcome for children with tympanostomy tubes. The evidence behind the potential harmful effects of water on the outcome of other otological procedures is scarce.

Objective: The study was done to determine the current practice of otolaryngology consultants in the UK on the advice given to patients regarding swimming, diving and bathing in soapy water after myringotomy and tympanostomy tube insertion, mastoidectomy and myringoplasty.

Method: Questionnaire based survey mailed to 382 members (consultants only) of the British Association of Otolaryngologists – Head & Neck Surgeons in the UK.

Results: A total of 195 responses were received (reply rate 51 per cent). In all, 95.6 per cent of the respondents allowed their patients to swim after insertion of tympanostomy tubes, with 32.9 per cent insisting on the use of earplugs until extrusion of the tympanostomy tubes. However, 61.6 per cent of the respondents restricted diving in these patients. In comparison, the respondents were more conservative with water precautions following myringoplasty and mastoidectomy. More than half the respondents recommended earplugs for bathing after all three operations.

Conclusion: This study reveals current national practice among UK otolaryngologists. There is no general consensus in post-operative advice following otolaryngological procedures, indicating a need for national guidelines.
The maturation of balance in children
Authors: Cumberworth V L , Patel N N , Rogers W , Kenyon G S
Published: November 2006

Background: Balance function is known to change with age during infancy and childhood. However, the relative contributions of the three primary inputs to position sense are not fully understood.

Methods: In this paper we report the computerised dynamic posturography findings in a group of 60 healthy children from the age of five to 17.

Results: The results confirm that there is a progressive improvement in balance function with age. The EquiTest system that was used gave indications of the relative contributions of the three principal contributors to overall balance function and showed that somatosensory function was intact throughout the age range tested and that there are significant increases in vestibular function with age and visual contribution with height. The technique used was found to be reliable and repeatable in this paediatric sample.

Conclusions: It is hoped that a better understanding of the normal age related development of balance will be helpful in dealing with children presenting with disequilibrium and vertigo.
Groundwater characteristics at Seabee Hook, Cape Hallett, Antarctica
Authors: Hofstee Erica H. , Campbell Dave I. , Balks Megan R. , Aislabie Jackie
Published: November 2006

Seabee Hook is a low lying gravel spit adjacent to Cape Hallett, northern Victoria Land, in the Ross Sea region of Antarctica and hosts an Adélie penguin (Pygoscelis adeliae) rookery. Dipwells were inserted to monitor changes in depth to, and volume of, groundwater and tracer tests were conducted to estimate aquifer hydraulic conductivity and groundwater velocity. During summer (November–February), meltwater forms a shallow, unconfined, aquifer perched on impermeable ice cemented soil. Groundwater extent and volume depends on the amount of snowfall as meltwater is primarily sourced from melting snow drifts. Groundwater velocity through the permeable gravel and sand was up to 7.8 m day−1, and hydraulic conductivities of 4.7 × 10−4 m s−1 to 3.7 × 10−5 m s−1 were measured. The presence of the penguin rookery, and the proximity of the sea, affects groundwater chemistry with elevated concentrations of salts (1205 mg L−1 sodium, 332 mg L−1 potassium) and nutrients (193 mg L−1 nitrate, 833 mg L−1 ammonia, 10 mg L−1 total phosphorus) compared with groundwater sourced away from the rookery, and with other terrestrial waters in Antarctica.
The effects of joint ENSO–Antarctic Oscillation forcing on the McMurdo Dry Valleys, Antarctica
Authors: Bertler N.A.N. , Naish T.R. , Oerter H. , Kipfstuhl S. , Barrett P.J. , Mayewski P.A. , Kreutz K.
Published: November 2006

Stable oxygen analyses and snow accumulation rates from snow pits sampled in the McMurdo Dry Valleys have been used to reconstruct variations in summer temperature and moisture availability over the last four decades. The temperature data show a common interannual variability, with strong regional warmings occurring especially in 1984/85, 1995/96 and 1990/91 and profound coolings during 1977/78, 1983/84, 1988/89, 1993/94, and 1996/97. Annual snow accumulation shows a larger variance between sites, but the early 1970s, 1984, 1997, and to a lesser degree 1990/91 are characterized overall by wetter conditions, while the early and late 1980s show low snow accumulation values. Comparison of the reconstructed and measured summer temperatures with the Southern Oscillation Index (SOI) and the Antarctic Oscillation (AAO) yield statistically significant correlations, which improve when phase-relationships are considered. A distinct change in the phase relationship of the correlation is observed, with the SOI-AAO leading over the temperature records by one year before, and lagging by one year after 1988. These results suggest that over the last two decades summer temperatures are influenced by opposing El Niño Southern Oscillation and AAO forcings and support previous studies that identified a change in the Tropical-Antarctic teleconnection between the 1980s and 1990s.
PChemistry and stratification of Antarctic meltwater ponds I: Coastal ponds near Bratina Island, McMurdo Ice Shelf
Authors: Wait B.R. , Webster-Brown J.G. , Brown K.L. , Healy M. , Hawes I.
Published: November 2006

The geochemistry and vertical stratification of shallow meltwater ponds at 78°S near Bratina Island (McMurdo Ice Shelf) have been determined for late winter (October) and summer (January) conditions as part of the Latitudinal Gradient Project. Of the five frozen ponds investigated in October, all were stratified with respect to conductivity, and three had highly saline basal brines beneath the ice at temperatures of −16 to −20°C. In the ice column, inclusions of saline fluid were observed in channels between ice crystals; the abundance increasing with depth and decreasing ice crystal size. In January, seven of the ten ponds investigated (including ponds sampled in October) retained conductivity stratification, whereas significant thermal stratification was observed in only three ponds (maximum ΔT = 5.5°C). Basal brines, ice and meltwaters were Na-Cl or Na-SO4 dominated. FREZCHEM52 modelling, supported by changes in ion ratios, indicated that the precipitation of mirabilite (Na2SO4.10H2O) and gypsum (CaSO4.2H2O) during progressive freezing is an important determinant in chemical evolution of the basal brine. High pH (8.8–11.2) and over-saturation with respect to dissolved oxygen (> 20 mg L−1) in summer, and the presence of sulphide ions in basal brines in winter, occurred in those ponds which experienced high biological productivity during the summer months.
Chemistry and stratification of Antarctic meltwater ponds II: Inland ponds in the McMurdo Dry Valleys, Victoria Land
Authors: Healy M. , Webster-Brown J.G. , Brown K.L. , Lane V.
Published: November 2006

Meltwater ponds in the Victoria Valley and in the Labyrinth at the head of the Wright Valley of Victoria Land were sampled in January (summer) and October (late winter) of 2004 to establish their geochemistry and stratification, and to compare this with that of coastal meltwater ponds at a similar latitude near Bratina Island. In summer, vertical profiles were measured in 14 ponds; 10 were thermally stratified (maximum ΔT = 11.5°C) and 12 demonstrated a conductivity increase (∼25x) in the lowest 10–20 cm of the water column. When 11 of these ponds were resampled in October, the ice columns were stratified with respect to conductivity and five ponds had highly saline (up to 148 mS cm−1), oxygenated basal brines present under the ice. Basal brines and summer melt waters were Na-Cl dominated, and Victoria Valley pond meltwaters were enriched in Ca relative to the Labyrinth ponds. Early gypsum precipitation directs the chemical evolution of residual brine during freezing. These ponds were enriched in NO3 relative to the coastal ponds at Bratina Island, due to dissolution of nitrate-bearing soil salts, and the reduced influence of marine aerosols and biological productivity on pond chemistry.
Two genetic and ecological groups of Nostoc commune in Victoria Land, Antarctica, revealed by AFLP analysis
Authors: Novis Phil M. , Smissen Rob D.
Published: November 2006

Microscopy, DNA sequencing, and amplified fragment length polymorphism (AFLP) were used to examine variation within Nostoc commune from collections between 72 and 78°S in Victoria Land, Antarctica. Although there is considerable bias of collected material towards southern latitudes, and this material varies greatly in age (collected between 1984 and 2004), an important new phylogeographic pattern was found. DNA sequencing of the tRNAleu(UAA) region, used recently to define form species N. commune, revealed little variation between collections. AFLP analysis, however, split the collected material according to habitat (irrigated soil communities versus ponds), rather than latitude. These results suggest that environmental factors linked to latitude are not the greatest drivers of genetic variation in Victoria Land. These may operate at a lower level but would require intensive sampling within narrowly defined habitat types at a range of latitudes to uncover. We advocate extensive sampling across local environmental gradients based on water availability, comparative culturing, and development of sequence characterised amplified regions (SCARs) across a range of latitudes in future seasons of the Latitudinal Gradient Project.
Water column features and their relationship with sediments and benthic communities along the Victoria Land coast, Ross Sea, summer 2004
Authors: Povero Paolo , Castellano Michela , Ruggieri Nicoletta , Monticelli Luis S. , Saggiomo Vincenzo , Chiantore Mariachiara , Guidetti Marta , Cattaneo-Vietti Riccardo
Published: November 2006

The northern Victoria Land coastal marine environment was investigated during the late summer 2004, within the framework of the Latitudinal Gradient Project (LGP), to describe the physical, chemical and biological patterns of the water column and their relationship with the pelagic and benthic compartments, and to determine to what extent they change with latitude. A latitudinal gradient from Cape Adare to the Terra Nova Bay–Cape Russell area was determined on the basis of abiotic and trophic factors. Cape Adare had lower values of organic matter (particulate organic carbon < 150 μg l−1) available for the benthic communities, but this organic matter had good trophic quality. In Terra Nova Bay the particulate organic matter was quantitatively higher (organic carbon > 400 μg l−1), presumably reaching the bottom via faecal pellets, but was more detrital, although its nutritive value was still high (carbon protein content nearly 40%), as confirmed by the great quantity of phytopigments in the sediments (> 4.0 μg g−1). The benthic communities changed with latitude as well, partially reflecting the environmental and trophic gradient, but also showing a large within-area variability (except for the Cape Adare area), due to a complex array of variables that did not change with latitude.
Meridional circulation during the Last Glacial Maximum explored through a combination of South Atlantic δ18O observations and a geostrophic inverse model
Authors: Gebbie Geoffrey , Huybers Peter
Published: November 2006

The vertical profile of meridional transport in the South Atlantic is examined by combining paleoceanographic observations with a geostrophic circulation model using an inverse method. δ18Ocalcite observations along the margins of the South Atlantic show that upper‐ocean cross‐basin differences were weaker during the Last Glacial Maximum (LGM) than the Holocene. The δ18Ocalcite observations can be explained by a shift of water‐mass properties without any change in the overturning circulation. Alternatively, they may indicate a reduced LGM cross‐basin density difference and, via the thermal wind relation, a reduced vertical shear. Model inversions of δ18Ocalcite are found to require meridional transports different from the modern only after three assumptions are made: temperature and salinity distributions are spatially smooth, the relationship between salinity and δ18Owater is linear and spatially invariant, and LGM temperatures are known to within 1°C along the margins. The last assumption is necessary because an independent constraint on temperature or salinity is required to determine density from δ18Ocalcite observations. δ18Ocalcite observations are clearly useful, but before any firm constraints can be placed on LGM meridional transport, it appears necessary to better determine the relationship between δ18Ocalcite and density.
Impact of ENSO on landfall characteristics of tropical cyclones over the western North Pacific during the summer monsoon season
Authors: Fudeyasu H. , Iizuka S. , Matsuura T.
Published: November 2006

We investigate the impact of ENSO on the landfall characteristics of tropical cyclones (TC) over the Western North Pacific (WNP) during the summer monsoon season. During the early monsoon period (late May–late July), an increase in the numbers of TCs that make landfall in the Korean Peninsula or Japan is associated with an increase in the Niño‐3.4 SST anomalies. During the peak monsoon period (late July–mid September), the number of TCs that make landfall in the Indochinese Peninsula is greater in El Niño years than in La Niña years. Furthermore, in El Niño years, the TCs that make landfall in the Korean Peninsula or Japan tend to have longer lifespan and greater intensities. These changes can be primarily attributed to the change in the mean TC formation location as a result of ENSO.
Evaluation of ISLSCP Initiative II satellite‐based land cover data sets and assessment of progress in land cover data for global modeling
Authors: Brown de Colstoun Eric C. , DeFries Ruth S. , Townshend John R. G.
Published: November 2006

As an important component of the International Satellite Land Surface Climatology Project (ISLSCP) Initiative II data collection, eight state‐of‐the‐art land cover/use data sets have been compiled and made consistent with the ISLSCP Initiative II land/water mask in support of global modeling efforts. These data sets contain new and improved global data sets at coarse resolutions (1/4, 1/2 and 1°) describing historical, recent and present land cover conditions and are a testament to the tremendous progress made in this area over the past decade. In addition to the historical data, data describing the subcell heterogeneity in land cover are also provided, both in terms of subcell proportions of land cover classes and vegetation continuous fields such as % tree, grass and bare cover. Here we present the various ISLSCPII land cover data sets and compare the principal satellite‐derived data sets and the effect of their respective aggregation methods. We find that despite some notable disagreements among similar classes, the satellite‐based data sets agree remarkably well over large portions of the Earth's surface (over 50% for all resolutions). We also find that the methods of aggregation, whether done by a strictly dominant type, or using more information on subcell tree cover, can have an important impact on the final output and need to be considered by the user. Finally, by integrating the vegetation continuous fields data into our analyses we are able to show that the principal differences in terms of discrete land cover classes are in fact transition zones between similar classes.
Gangliosides play an important role in the organization of CD82-enriched microdomains
Authors: Odintsova Elena , Butters Terry D. , Monti Eugenio , Sprong Hein , van Meer Gerrit , Berditchevski Fedor
Published: November 2006

Four-transmembrane-domain proteins of the tetraspanin superfamily are the organizers of specific microdomains at the membrane [TERMs (tetraspanin-enriched microdomains)] that incorporate various transmembrane receptors and modulate their activities. The structural aspects of the organization of TERM are poorly understood. In the present study, we investigated the role of gangliosides in the assembly and stability of TERM. We demonstrated that inhibition of the glycosphingolipid biosynthetic pathway with specific inhibitors of glucosylceramide synthase [NB-DGJ (N-butyldeoxygalactonojirimycin) and PPMP (D-threo-1-phenyl-2-hexadecanoylamino-3-morpholino-1-propanol·HCl)] resulted in specific weakening of the interactions involving tetraspanin CD82. Furthermore, ectopic expression of the plasma-membrane-bound sialidase Neu3 in mammary epithelial cells also affected stability of the complexes containing CD82: its association with tetraspanin CD151 was decreased, but the association with EGFR [EGF (epidermal growth factor) receptor] was enhanced. The destabilization of the CD82-containing complexes upon ganglioside depletion correlated with the re-distribution of the proteins within plasma membrane. Importantly, depletion of gangliosides affected EGF-induced signalling only in the presence of CD82. Taken together, our results provide strong evidence that gangliosides play an important role in supporting the integrity of CD82-enriched microdomains. Furthermore, these results demonstrate that the association between different tetraspanins in TERM is controlled by distinct mechanisms and identify Neu3 as a first physiological regulator of the integrity of these microdomains.
The ARE-associated factor AUF1 binds poly(A) in vitro in competition with PABP
Authors: Sagliocco Francis , Laloo Benoît , Cosson Bertrand , Laborde Laurence , Castroviejo Michel , Rosenbaum Jean , Ripoche Jean , Grosset Christophe
Published: November 2006

The ARE (AU-rich element) is a post-transcriptional element controlling both mRNA turnover and translation initiation by primarily inducing poly(A) tail shortening. The mechanisms by which the ARE-associated proteins induce deadenylation are still obscure. One possibility among others would be that an ARE–ARE-BP (ARE-binding protein) complex intervenes in the PABP [poly(A)-binding protein]–poly(A) tail association and facilitates poly(A) tail accessibility to deadenylases. Here, we show by several experimental approaches that AUF1 (AU-rich element RNA-binding protein 1)/hnRNP (heterogeneous nuclear ribonucleoprotein) D, an mRNA-destabilizing ARE-BP, can bind poly(A) sequence in vitro. First, endogenous AUF1 proteins from HeLa cells specifically bound poly(A), independently of PABP. Secondly, using polyadenylated RNA probes, we showed that (i) the four recombinant AUF1 isoforms bind poly(A) as efficiently as PABP, (ii) the AUF1 binding to poly(A) does not change when the polyadenylated probe contains the GM-CSF (granulocyte/macrophage-colony stimulating factor) ARE, suggesting that, in vitro, the AUF1–poly(A) association was independent of the ARE sequence itself. In vitro, the binding of AUF1 isoforms to poly(A) displayed oligomeric and co-operative properties and AUF1 efficiently displaced PABP from the poly(A). Finally, the AUF1 molar concentration in HeLa cytoplasm was only 2-fold lower than that of PABP, whereas in the nucleus, its molar concentration was similar to that of PABP. These in vitro results suggest that, in vivo, AUF1 could compete with PABP for the binding to poly(A). Altogether, our results may suggest a role for AUF1 in controlling PABP–poly(A) tail association.
CUG-BP1/CELF1 requires UGU-rich sequences for high-affinity binding
Authors: Marquis Julien , Paillard Luc , Audic Yann , Cosson Bertrand , Danos Olivier , Le Bec Christine , Osborne H. Beverley
Published: November 2006

CUG-BP1 [CUG-binding protein 1 also called CELF (CUG-BP1 and ETR3 like factors) 1] is a human RNA-binding protein that has been implicated in the control of splicing and mRNA translation. The Xenopus homologue [EDEN-BP (embryo deadenylation element-binding protein)] is required for rapid deadenylation of certain maternal mRNAs just after fertilization. A variety of sequence elements have been described as target sites for these two proteins but their binding specificity is still controversial. Using a SELEX (systematic evolution of ligand by exponential enrichment) procedure and recombinant CUG-BP1 we selected two families of aptamers. Surface plasmon resonance and electrophoretic mobility-shift assays showed that these two families differed in their ability to bind CUG-BP1. Furthermore, the selected high-affinity aptamers form two complexes with CUG-BP1 in electrophoretic mobility assays whereas those that bind with low affinity only form one complex. The validity of the distinction between the two families of aptamers was confirmed by a functional in vivo deadenylation assay. Only those aptamers that bound CUG-BP1 with high affinity conferred deadenylation on a reporter mRNA. These high-affinity RNAs are characterized by a richness in UGU motifs. Using these binding site characteristics we identified the Xenopus maternal mRNA encoding the MAPK (mitogen-activated protein kinase) phosphatase (XCl100α) as a substrate for EDEN-BP. In conclusion, high-affinity CUG-BP1 binding sites are sequence elements at least 30 nucleotides in length that are enriched in combinations of U and G nucleotides and contain at least 4 UGU trinucleotide motifs. Such sequence elements are functionally competent to target an RNA for deadenylation in vivo.
Ubiquitin–proteasome degradation of serum- and glucocorticoid-regulated kinase-1 (SGK-1) is mediated by the chaperone-dependent E3 ligase CHIP
Authors: Belova Larissa , Sharma Sanjay , Brickley Deanna R. , Nicolarsen Jeremy R. , Patterson Cam , Conzen Suzanne D.
Published: November 2006

SGK-1 (serum- and glucocorticoid-regulated kinase-1) is a stress-induced serine/threonine kinase that is phosphorylated and activated downstream of PI3K (phosphoinositide 3-kinase). SGK-1 plays a critical role in insulin signalling, cation transport and cell survival. SGK-1 mRNA expression is transiently induced following cellular stress, and SGK-1 protein levels are tightly regulated by rapid proteasomal degradation. In the present study we report that SGK-1 forms a complex with the stress-associated E3 ligase CHIP [C-terminus of Hsc (heat-shock cognate protein) 70-interacting protein]; CHIP is required for both the ubiquitin modification and rapid proteasomal degradation of SGK-1. We also show that CHIP co-localizes with SGK-1 at or near the endoplasmic reticulum. CHIP-mediated regulation of SGK-1 steady-state levels alters SGK-1 kinase activity. These data suggest a model that integrates CHIP function with regulation of the PI3K/SGK-1 pathway in the stress response.
No association of the CYP3A5*1 allele with blood pressure and left ventricular mass and geometry: the KORA/MONICA Augsburg echocardiographic substudy
Authors: Lieb Wolfgang , Bolbrinker Juliane , Döring Angela , Hense Hans-Werner , Erdmann Jeanette , Schunkert Heribert , Kreutz Reinhold
Published: November 2006

A polymorphism in the cytochrome P450 3A CYP3A5 enzyme has been implicated in BP (blood pressure) control and arterial hypertension. Carriers of the CYP3A5*1 allele had high, whereas homozygous carriers of the CYP3A5*3 allele exhibit low, CYP3A5 expression in the kidney, where CYP3A5 represents the major CYP3A enzyme. The aim of the present study was to investigate the association of the CYP3A5*1 allele with BP, arterial hypertension, LVM [(left ventricular) mass] and LV geometry in a large Caucasian-population-based cohort. We compared BP, LVM and the prevalence of hypertension between carriers (CYP3A5*1/*1 and CYP3A5*1/*3 genotypes) and non-carriers (CYP3A5*3/*3 genotype) of the CYP3A5*1 allele in the echocardiographic substudy of the third MONICA (MONItoring trends and determinants in CArdiovascular disease) Augsburg survey. After exclusion of 269 individuals who were taking antihypertensive medication, 530 women and 554 men were available for analysis, revealing allele frequencies of 5.8 and 94.2% for the CYP3A5*1 and CYP3A5*3 alleles respectively. Overall, the presence of the CYP3A5*1 allele exhibited no effect on systolic or diastolic BP in either gender. One-third of the individuals in this cohort were hypertensive (BP ≥140/90 mmHg), and the genotype distribution between normotensive and hypertensive individuals revealed no association between CYP3A5*1 and hypertension after adjustment for age, BMI and gender (odds ratio, 1.02; P=0.92). Moreover, no effect of CYP3A5*1 on LVM, thickness of the septal and posterior wall and LV end-diastolic diameter was found. We conclude that CYP3A5*1 exhibits no significant effect on BP, LVM and LV geometry in the KORA/MONICA echocardiographic substudy.
Fluctuation microscopy evidence for enhanced nanoscale structural order in polymorphous silicon thin films
Authors: Nguyen-Tran T. , Suendo V. , Roca i Cabarrocas P. , Nittala L. N. , Bogle S. N. , Abelson J. R.
Published: November 2006

The nanometer-scale (medium range) structural order in hydrogenated polymorphous silicon films is analyzed using fluctuation electron microscopy. The polymorphous growth regime occurs under relatively high gas pressure during plasma-enhanced chemical vapor deposition, such that small aggregates and nanocrystals form in the gas phase and impinge on the film surface. All polymorphous samples appear completely amorphous in diffraction or Raman scattering analyses. In fluctuation microscopy, carried out in the transmission electron microscope, the statistical variance V in the dark field image intensity is acquired as a function of the scattering vector k at a chosen resolution Q. Theory shows that V is quantitatively related to the three- and four-body atomic correlation functions, and thus to the nanometer scale order, in the material. Unlike typical hydrogenated amorphous silicon, the variance V is a strong function of growth conditions and displays a maximum at a silane pressure of 1.4–1.8Torr. The images also reveal the presence of a small number of unusually bright spots, roughly 5nm in diameter, only in samples grown at 0.8 and 1.4Torr; we interpret that these correspond to nanocrystallites. The observation of enhanced structural order as revealed by the variance V is consistent with previous, but less conclusive, analyses of hydrogenated polymorphous silicon.
Harmonic oscillators coupled by springs: Discrete solutions as a Wigner quantum system
Authors: Lievens S. , Stoilova N. I. , Van der Jeugt J.
Published: November 2006

We consider a quantum system consisting of a one-dimensional chain of M identical harmonic oscillators with natural frequency ω, coupled by means of springs. Such systems have been studied before, and appear in various models. In this paper, we approach the system as a Wigner quantum system, not imposing the canonical commutation relations, but using instead weaker relations following from the compatibility of Hamilton’s equations and the Heisenberg equations. In such a setting, the quantum system allows solutions in a finite-dimensional Hilbert space, with a discrete spectrum for all physical operators. We show that a class of solutions can be obtained using generators of the Lie superalgebra gl(1∣M). Then we study – from a mathematical point of view – the properties and spectra of the physical operators in a class of unitary representations of gl(1∣M). These properties are both interesting and intriguing. In particular, we can give a complete analysis of the eigenvalues of the Hamiltonian and of the position and momentum operators (including multiplicities). We also study probability distributions of position operators when the quantum system is in a stationary state, and the effect of the position of one oscillator on the positions of the remaining oscillators in the chain.
Calculation of smooth potential energy surfaces using local electron correlation methods
Authors: Mata Ricardo A. , Werner Hans-Joachim
Published: November 2006

The geometry dependence of excitation domains in local correlation methods can lead to noncontinuous potential energy surfaces. We propose a simple domain merging procedure which eliminates this problem in many situations. The method is applied to heterolytic bond dissociations of ketene and propadienone, to SN2 reactions of Cl− with alkylchlorides, and in a quantum mechanical∕molecular mechanical study of the chorismate mutase enzyme. It is demonstrated that smooth potentials are obtained in all cases. Furthermore, basis set superposition error effects are reduced in local calculations, and it is found that this leads to better basis set convergence when computing barrier heights or weak interactions. When the electronic structure strongly changes between reactants or products and the transition state, the domain merging procedure leads to a balanced description of all structures and accurate barrier heights.
Three dimensional nanowire networks and complex nanostructures of indium oxide
Authors: Magdas Dana A. , Cremades Ana , Piqueras Javier
Published: November 2006

Elongated In2O3 micro- and nanostructures have been grown by two-step thermal treatments of compacted InN powder, at temperatures between 350 and 700°C. Different thermal treatments have been found to induce the growth of structures with different sizes and morphologies as wires, rods, or arrows. The experimental conditions leading to the different structures, as well as the evolution of the structures during the treatments, have been investigated. Some treatments lead to large scale formation of three dimensional networks of the mentioned structures. The mechanism of network formation is discussed. The structures have been characterized by cathodoluminescence, scanning electron microscopy, and x-ray diffraction.
Photodissociation spectroscopy of the Mg+-acetic acid complex
Authors: Abate Yohannes , Kleiber P. D.
Published: November 2006

We have studied the structure and photodissociation of Mg+-acetic acid clusters. Ab initio calculations suggest four relatively strongly bound ground state isomers for the [MgC2H4O2]+ complex. These isomers include the cis and trans forms of the Mg+-acetic acid association complex with Mg+ bonded to the carbonyl O atom of acetic acid, the Mg+-acetic acid association complex with Mg+ bonded to the hydroxyl O atom of acetic acid, or to a Mg+-ethenediol association complex. Photodissociation through the Mg+-based 3p←3s absorption bands in the near UV leads to direct (nonreactive) and reactive dissociation products: Mg+, MgOH+, Mg(H2O)+, CH3CO+, and MgCH3+. At low energies the dominant reactive quenching pathway is through dehydration to Mg(H2O)+, but additional reaction channels involving C–H and C–C bond activation are also open at higher energies.
Strong resonant luminescence from Ge quantum dots in photonic crystal microcavity at room temperature
Authors: Xia J. S. , Ikegami Y. , Shiraki Y. , Usami N. , Nakata Y.
Published: November 2006

Freestanding hexagonal two-dimensional photonic crystal (PhC) microcavities with Ge self-assembled quantum dots were fabricated on silicon-on-insulator substrates. Strong photoluminescence associated with Ge quantum dots was observed in the wavelength region of 1.2–1.6μm at room temperature. Sharp peaks dominated the spectrum, showing strong optical resonance inside the cavity. A resonant peak with a quality factor of 560 was observed at 1.58μm along with a significant enhancement of the luminescence in the microphotoluminescence spectrum. The peaks were also observed to reasonably shift when the structural parameter of PhC was changed.
Achieving optimum hydrogen permeability in PdAg and PdAu alloys
Authors: Sonwane Chandrashekhar G. , Wilcox Jennifer , Ma Yi Hua
Published: November 2006

The present work investigates both the diffusivity and permeability of hydrogen (H) in palladium-silver (PdAg) and palladium-gold (PdAu) alloys over a 400–1200K temperature range for Pd100−XMX, M=Ag or Au and X=0%–48% using density functional theory (DFT) and kinetic Monte Carlo simulations (KMC). DFT has been employed to obtain octahedral (O)-, tetrahedral (T)-, and transition state (TS)- site energetics as a function of local alloy composition for several PdAg and PdAu alloys with compositions in supercells of X=14.18%, 25.93%, 37.07%, and 48.15% with the nearest (NNs) and next nearest neighbors (NNNs) varied over the entire range of compositions. The estimates were then used to obtain a model relating the O, T, and TS energies of a given site with NNX, NNNX, and the lattice constant. The first passage approach combined with KMC simulations was used for the H diffusion coefficient predictions. It was found that the diffusion coefficient of H in PdAg alloy decreases with increasing Ag and increases with increasing temperature, matching closely with the experimental results reported in the literature. The calculated permeabilities of H in these novel binary alloys obtained from both diffusivity and solubility predictions were found to have a maximum at ∼20% Ag and ∼12% Au, which agree well with experimental predictions. Specifically, the permeability of H in PdAg alloy with ∼20% Ag at 456K is three to four times that of pure Pd, while the PdAu alloy at 12% Au is four to five times that of pure Pd at 456K.
Enhancement of ferromagnetic properties of NiO:Fe thin film by Li doping
Authors: Lin Yuan-Hua , Zhao Rongjuan , Nan Ce-Wen , Ying Minghao , Kobayashi M. , Ooki Y. , Fujimori A.
Published: November 2006

Li and Fe codoped NiO thin films (LixNi0.98−xFe0.02O, x=0–0.05) were obtained by a sol-gel spin-coating method on silicon substrates. Phase composition and microstructure analysis indicated that the film samples contained 20–30nm sized NiO particles. With increasing Li-doping concentration, the current density of the films increased due to the increase of hole carriers. Magnetization measurements revealed that all the thin films showed room-temperature ferromagnetic properties and could be enhanced by Li doping, which should be due to the fact that hole doping makes ferromagnetic coupling interactions between the hole carriers and localized Fe 3d spins more efficient.
Improvement on the temperature coefficient of resonant frequency of hexagonal perovskites through intergrowth structures
Authors: Zhao Fei , Yue Zhenxing , Pei Jing , Zhuang Hao , Gui Zhilun , Li Longtu
Published: November 2006

Cation-deficient hexagonal perovskites Ba5Nb4O15, Ba6Nb4TiO18, and their intergrowth compounds were prepared by solid-state reaction method. Dielectric measurements showed that the intergrowth compounds had a relatively low temperature coefficient of resonant frequency (τf) compared to that of the simple terms Ba5Nb4O15 and Ba6Nb4TiO18. On the basis of the structure data, the authors proposed a structural parameter d, the degree of atomic displacements, to evaluate the structural dependence of the temperature coefficient of resonant frequency. The reduced τf value of intergrowths was considered to be resulted from the decreased degree of atomic displacements in the hexagonal perovskite structure.
Emergence of primate genes by retrotransposon-mediated sequence transduction
Authors: Xing Jinchuan , Wang Hui , Belancio Victoria P. , Cordaux Richard , Deininger Prescott L. , Batzer Mark A.
Published: November 2006

Gene duplication is one of the most important mechanisms for creating new genes and generating genomic novelty. Retrotransposon-mediated sequence transduction (i.e., the process by which a retrotransposon carries flanking sequence during its mobilization) has been proposed as a gene duplication mechanism. L1 exon shuffling potential has been reported in cell culture assays, and two potential L1-mediated exon shuffling events have been identified in the genome. SVA is the youngest retrotransposon family in primates and is capable of 3′ flanking sequence transduction during retrotransposition. In this study, we examined all of the full-length SVA elements in the human genome to assess the frequency and impact of SVA-mediated 3′ sequence transduction. Our results showed that ≈53 kb of genomic sequences have been duplicated by 143 different SVA-mediated transduction events. In particular, we identified one group of SVA elements that duplicated the entire
AMAC
gene three times in the human genome through SVA-mediated transduction events, which happened before the divergence of humans and African great apes. In addition to the original
AMAC
gene, the three transduced
AMAC
copies contain intact ORFs in the human genome, and at least two are actively transcribed in different human tissues. The duplication of entire genes and the creation of previously undescribed gene families through retrotransposon-mediated sequence transduction represent an important mechanism by which mobile elements impact their host genomes.