bluuebunny/crossref_metadata_2025_split huggingface dataset:
Peroxisome proliferator‐activated receptor γ (PPAR) agonism reduces the insulin‐stimulated increase in circulating interleukin‐6 in GH replaced GH‐deficient adults
Authors: Krag Morten B. , Rasmussen Lars M. , Hansen Troels K. , Frystyk Jan , Flyvbjerg Allan , Møller Niels , Jørgensen Jens O. L. 
Published: December 2008

SummaryContext  Peroxisome proliferator‐activated receptor γ (PPARγ) agonists modify cardiovascular risk factors and inflammatory markers in patients with type 2 diabetes. GH treatment in GH‐deficient (GHD) patients may cause insulin resistance and exerts ambiguous effects on inflammatory markers.Objective  To investigate circulating markers of inflammation and endothelial function in GH replaced GHD patients before and after 12 weeks administration of either pioglitazone 30 mg/day (N = 10) or placebo (N = 10) in a randomized double‐blind parallel design.Methods  Circulating levels of interleukins (ILs)‐1β, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, tumour necrosis factor (TNF)‐α, high sensitivity C‐reactive protein, vascular cell adhesion molecule‐I, and osteoprotegerin (OPG) were measured in the basal state and after a 2·5 h hyperinsulinaemic euglycaemic clamp.Results  Insulin sensitivity improved in the group receiving PPARγ agonist (P = 0·03). Serum IL‐6 levels increased by 114 ± 31% (mean ± SE) in the entire group (N = 20) following the hyperinsulinaemic euglycaemic clamp (P = 0·01) performed at study start. Twelve weeks of PPARγ agonist treatment significantly abrogated this insulin‐stimulated increment in IL‐6 levels compared to placebo (P = 0·01). Furthermore PPARγ agonist treatment significantly lowered basal IL‐4 levels (P < 0·05).Conclusions  (i) IL‐6 levels increase during a hyperinsulinaemic clamp in GH replaced patients (ii) This increase in IL‐6 is abrogated by PPARγ agonist treatment (iii) we hypothesize that PPARγ agonist‐induced improvement of insulin sensitivity may obviate a compensatory rise in IL‐6.
Low O6‐methylguanine‐DNA methyltransferase (MGMT) expression and response to temozolomide in aggressive pituitary tumours
Authors: McCormack Ann I. , McDonald Kerrie L. , Gill Anthony J. , Clark Susan J. , Burt Morton G. , Campbell Kirsten A. , Braund Wilton J. , Little Nicholas S. , Cook Raymond J. , Grossman Ashley B. , Robinson Bruce G. , Clifton‐Bligh Roderick J. 
Published: December 2008

SummaryContext  Recent case reports detail the successful use of temozolomide in the management of aggressive pituitary tumours. O6‐methylguanine‐DNA methyltransferase (MGMT) is a DNA repair protein that counteracts the effect of temozolomide.Objective  To study MGMT expression in pituitary tumours and consider whether MGMT expression is associated with response to temozolomide therapy in aggressive pituitary tumours.Patients  We report two patients with aggressive pituitary tumours treated with temozolomide, one who responded to temozolomide and the other who did not. MGMT expression was assessed in a further 88 archived pituitary tumour samples.Design  MGMT expression was assessed by immunohistochemistry. MGMT promoter methylation was studied by methylation‐specific polymerase chain reaction (MSP), sequencing of MGMT was performed and loss of heterozygosity (LOH) analysis undertaken.Results  Low MGMT expression and MGMT promoter methylation were found in the pituitary tumour of the patient who responded to temozolomide. Conversely, high MGMT expression was seen in the patient demonstrating a poor response to temozolomide. Eleven out of 88 archived tumour samples (13%) had low MGMT expression. Prolactinomas were more likely to have low MGMT expression compared with other pituitary tumour subtypes (P < 0·001). There was no significant difference in MGMT expression between invasive and noninvasive tumours, or between recurrent and nonrecurrent tumours. A significant inverse correlation was found between MGMT expression and promoter methylation (P = 0·012).Conclusion  MGMT expression as assessed by immunohistochemistry may predict response to temozolomide therapy in patients with aggressive pituitary tumours. MGMT promoter methylation is likely to explain low MGMT expression in some, but not all, pituitary tumours.
Beta‐adrenergic agonism does not impair the GH response to acylated ghrelin in humans
Authors: Benso A. , Gramaglia E. , Prodam F. , Riganti F. , Gigliardi V. Ramella , Lucatello B. , Olivetti I. , St Pierre D. , Ghigo E. , Broglio F. 
Published: December 2008

SummaryBackground  Acylated ghrelin (AG) is a physiological GH secretion amplifier, in part stimulating GHRH neurones and antagonizing somatostatin activity. In humans, AG is one of the most potent pharmacological stimuli of GH secretion and, unlike GHRH, is refractory to the inhibitory effect of glucose, free fatty acids (FFA) and somatostatin. Somatotroph secretion is also profoundly modulated by the adrenergic system. Indeed, beta‐adrenergic agonists abolish spontaneous and GHRH‐stimulated GH secretion. Based on these data, the aim of the present study was to investigate the effects of beta adrenergic agonism on the GH response to AG.Subjects and measurements  Six young healthy male volunteers underwent: (a) acute AG intravenous (iv) administration (1·0 µg/kg); (b) salbutamol infusion (SLB; 0·06 µg/kg/min iv); (c) AG + SLB; and (d) saline infusion. In all sessions GH levels were assayed every 15 min from time –30 to +210 min.Results  SLB induced a significant (P < 0·05) inhibition of spontaneous GH secretion that persisted up to 75 min after SLB withdrawal. AG induced a marked increase (P < 0·01) in GH that was not modified by SLB.Conclusions  The GH‐releasing effect of AG is refractory to the inhibitory effect of SLB‐induced beta‐adrenergic receptor activation. Although further studies are needed to confirm these results during the lifespan and particularly during prolonged exposure to beta agonists, the present data clearly suggest that, among GH stimulatory tests, AG administration might be the most suitable in clinical conditions of chronic treatment with beta‐2 agonists, such as in asthmatic disease.
Modelling changes in soil organic matter after planting fast‐growingPinus radiataon Mediterranean agricultural soils
Authors: Romanyà J. , Cortina J. , Falloon P. , Coleman K. , Smith P. 
Published: December 2008

SummaryThe Kyoto Protocol explicitly allows the storage of carbon (C) in ecosystems resulting from afforestation to be offset against a nation's carbon emissions and paves the way for carbon storage in soils to be eligible as carbon offsets in the future. More information is required about how afforestation affects carbon storage, especially in the soil. We report a study in which soil carbon storage in first‐rotation MediterraneanPinus radiataplantations, established on former cereal fields and vineyards, was measured and modelled. Measurements were made on plantations of several ages, as well as repeat measurements at the same site after 5 years. We tested the ability of two widely used soil organic matter models (RothC and Century) to predict carbon sequestration in Mediterranean forest soils.Increases in the top 5 cm of soil of about 10 g C m−2 year−1were observed after afforestation of former vineyards, but nitrogen (N) either remained the same or decreased slightly. During afforestation, most organic matter accumulated in the ectorganic layers at a rate of 19 g C m−2 year−1in former vineyards and 41 g C m−2 year−1in former cereal fields. The RothC and Century models were sensitive to previous land use and estimated a carbon sequestration potential over 20 years of 950 and 700 g C m−2, respectively. The accurate simulation of the dynamics of soil organic matter by RothC, together with measured above‐ground inputs, allowed us to calculate below‐ground inputs during afforestation. The Century model simulated total C and N, including the ectorganic horizons, well. Simulations showed a depletion of N in the below‐ground fractions during afforestation, with N limitation in the former vineyard but not on former cereal land. The approach demonstrates the potential of models to enhance our understanding of the processes leading to carbon sequestration in soils.
Distribution of microbial biomass and phospholipid fatty acids in Podzol profiles under coniferous forest
Authors: Fritze H. , Pietikäinen J. , Pennanen T. 
Published: December 2008

SummaryMicrobial‐derived phospholipid fatty acids (PLFAs) can be used to characterize the microbial communities in soil without the need to isolate individual fungi and bacteria. They have been used to assess microbial communities of humus layers under coniferous forest, but nothing is known of their distribution in the deeper soil. To investigate the vertical distribution we sampled nine Podzol profiles on a 100‐m‐long transect in a coniferous forest and analysed for their microbial biomass and PLFA pattern to a depth of 0.4 m. The transect covered a fertility gradient from Vaccinium vitis‐idaea forest site type to Vaccinium myrtillus forest site type. The cores were divided into humus (O) and eluvial (E) layers and below that into 10‐cm sections and designated as either illuvial (B) or parent material (C), or as a combination (BC). Two measures of microbial biomass analyses were applied: substrate‐induced respiration (SIR) to determine microbial biomass C (Cmic), and the sum of the extracted microbial‐derived phospholipid fatty acids (totPLFA). The soil fertility had no effect on the results. The Cmic correlated well with totPLFA (r= 0.86). The microbial biomass decreased with increasing depth. In addition the PLFA pattern changed with increased depth as assessed with principal component analysis, indicating a change in the microbial community structure. The composition of the PLFAs in the O layer differed from that in the E layer and both differed from the upper part of the B layer and from the rest of the BC layers. The deeper parts of the B layer (BC1, BC2 and BC3) were similar to one other. The O layer had more 18:2ω6, a PLFA indicator of fungi, whereas the E layer contained relatively more of the PLFAs 16:1ω9, 18:1ω7 and cy19:0 common in gram‐negative bacteria. With increased depth the relative amount of 10Me18:0, the PLFA indicator for actinomycetes, increased. We conclude that the PLFA method is a promising discriminator between the microbial community structures of the horizons in Podzols.
Interactions of aluminium and fulvic acid in moderately acid solutions: stoichiometry of the H+/Al3+ exchange
Authors: Simonsson M. 
Published: December 2008

SummaryComplexation with organic matter controls the activity of dissolved Al3+ in many soils. The buffering intensity of these soils is largely dependent on the H+/Al3+ exchange ratio, i.e. the number of protons consumed by the solid phase when one Al3+ is released. Here, the H+/Al3+ exchange ratio was determined from batch titrations using solutions of fulvic acid (FA) as a model for soil organic matter. Aluminium was added, from 1.04 to 6.29 mmol Al per g FA, which is within the range of humus‐bound Al found in the upper B horizon of podzolized soils. Furthermore, pH was varied with NaOH to give values between 3.5 and 5.0. The H+/Al3+ exchange ratio ranged between 1.49 and 2.23 with a mean of 1.94. It correlated positively with pH and the total concentration of Al present. Theoretically, this can be explained with a partial hydrolysis of bound Al. The slope of logAl (log10 of Al3+ activity) against pH generally underestimated the actual exchange ratio, which can partly be attributed to the systems being diluted (100 mg FA l−1). However, where 4 mmol Al or more had been added per g FA, the logAl slope gradually approached −3 between pH 4.5 and 5.0. This might be the result of a shift from Al3+ activity control by humus complexation to control by Al(OH)3(s).
Towards a predictive framework for predator risk effects: the interaction of landscape features and prey escape tactics
Authors: Heithaus Michael R. , Wirsing Aaron J. , Burkholder Derek , Thomson Jordan , Dill Lawrence M. 
Published: December 2008

Summary

Risk effects of predators can profoundly affect community dynamics, but the nature of these effects is context dependent.
Although context dependence has hindered the development of a general framework for predicting the nature and extent of risk effects, recent studies suggest that such a framework is attainable if the factors that shape anti‐predator behaviour, and its effectiveness, in natural communities are well understood.
One of these factors, the interaction of prey escape tactics and landscape features, has been largely overlooked.
We tested whether this interaction gives rise to interspecific variation in habitat‐use patterns of sympatric large marine vertebrates at risk of tiger shark (Galeocerdo cuvier Peron and LeSueur, 1822) predation. Specifically, we tested the a priori hypothesis that pied cormorants (Phalacrocorax varius Gmelin, 1789) would modify their use of shallow seagrass habitats in a manner opposite to that of previously studied dolphins (Tursiops aduncus Ehrenberg, 1833), dugongs (Dugong dugon Müller, 1776), and green turtles (Chelonia mydas Linnaeus, 1758) because, unlike these species, the effectiveness of cormorant escape behaviour does not vary spatially.
As predicted, cormorants used interior and edge portions of banks proportional to the abundance of their potential prey when sharks were absent but shifted to interior portions of banks to minimize encounters with tiger sharks as predation risk increased. Other shark prey, however, shift to edge microhabitats when shark densities increase to take advantage of easier escape despite higher encounter rates with sharks.
The interaction of landscape features and escape ability likely is important in diverse communities.
When escape probabilities are high in habitats with high predator density, risk effects of predators can reverse the direction of commonly assumed indirect effects of top predators.
The interaction between landscape features and prey escape tactics can result in a single predator species having differential effects on their sympatric prey that could cascade through ecosystems and should be incorporated into a general framework for context dependence of risk effects.
Restoration and recovery from acidification in upland Welsh streams over 25 years
Authors: Ormerod S. J. , Durance Isabelle 
Published: December 2008

Summary

Streams affected by acid deposition should now be recovering biologically, but long‐term assessments are scarce. Here, we use the experimental catchments at Llyn Brianne (Wales, UK) to evaluate trends over 25 years (1981–2005) in the chemistry and macroinvertebrates of acid moorland and forest streams restored by liming relative to those responding ‘naturally’ to reduced deposition.
Mean H+ concentrations in acid moorland streams fell by c. 15–16 µquiv L−1 over the study, increasing mean winter pH by 0·8–1·3 units to pH 5·6–6·1. Liming moorland streams in 1987 and 1988 increased mean pH to 5·5–6·4, but differences from naturally recovering streams diminished over 12–18 years.
In limed and acid moorland streams, changes in invertebrate composition were consistent with recovery, and near‐identical. Four acid‐sensitive species, from a local pool of 29, increased significantly in abundance or occurrence, but effects were too small to increase similarity with circumneutral reference streams.
Mean H+ in acid forest streams declined by 8–15 µequiv L−1, but mean winter pH increased by only 0·4 units and remained too acid for invertebrate recovery (mean pH 4·8–5·2; Al > 0·3–0·6 mg L−1). One forest stream limed in 1987 and 1988 remained at mean pH > 5·9 thereafter, but there was no invertebrate response.
Climate affected recovery pattern. After accounting for time trends, wet winters increased acidity in moorland and forest streams sufficiently to offset 21–41% of the total 25‐year decrease in H+ concentration.
Synthesis and applications. These data from one of the world's longest running experiments on acidification confirm that upland British streams are recovering, but ecological effects are marginal and vary with land use. Conifer forest streams at Llyn Brianne remain too acid for sensitive invertebrates, while moorland streams are still at risk from acid events. In this example, liming had few long‐term benefits compared with natural recovery, and we suggest that this should be a key, general criterion in evaluating the outcomes of ecological restoration.
Why does Dasineura dielsi‐induced galling of Acacia cyclops not impede vegetative growth?
Authors: Moseley C. T. , Cramer M. D. , Kleinjan C. A. , Hoffmann J. H. 
Published: December 2008

Summary

Conventionally, agent host specificity has been the major concern in the selection of prospective agents for biological control of weeds. However, subtle interactions between agent and host plant that could influence the outcome of the biological control programme also need to be identified and assessed when selecting potential agents.
A gall‐forming cecidomyiid Dasineura dielsi was introduced into South Africa for biological control of an invasive tree species, Acacia cyclops. Galls of D. dielsi form on flowers and prevent seed production, the intended aim of the biological control programme. Possible indirect effects of gall induction on vegetative growth of A. cyclops were investigated.
The carbon costs of producing and maintaining galls and pods were compared by measuring their gas exchange characteristics, and those of subtending phyllodes. Relocation of 14C from phyllodes to galls and pods, and nutrient composition of galls and pods, were compared. Insecticide was used to exclude D. dielsi from trees, enabling comparison of growth rates of predominantly gall‐bearing and predominantly podded branches.
Removal of galls, but not of pods, elevated photosynthetic rates of subtending phyllodes, indicating greater photosynthate demand by galls than pods. In light, the photosynthetic rates of expanded pods exceeded respiration rates. In contrast, there was a net release of CO2 from all age classes of galls in both light and dark. 14C allocation to mature galls was approximately three times as high as it was to young galls or immature pods.
Pod production required more mineral nutrient than gall production, with N, P and Ca contents of mature pods (including seeds) being nine‐fold those of mature galls.
Increases in stem diameters (i.e. vegetative growth rates) were similar for predominantly gall and predominantly pod bearing trees.
Synthesis and applications. Although nutrient costs were lower for galls than pods, this advantage was offset by higher carbon costs of gall production and the influence on plant growth was neutral. These findings illustrate that subtle physiological effects of herbivorous insects may influence the ecology of their hosts and should be considered during screening of potential agents for biological control.
Genetic correlates of protection against HIV infection: the ally within
Authors: Piacentini L. , Biasin M. , Fenizia C. , Clerici M. 
Published: December 2008

Abstract.Repeated exposure to HIV does not necessarily result in infection and HIV infection does not inevitably lead to the development of the AIDS. Multiple immunological and genetic features can confer resistance to HIV acquisition and progression at different steps in viral infection; a full understanding of these mechanisms could result in the development of novel therapeutic and vaccine approaches for HIV infection. In this review, we focus on the genetic mechanisms associated with resistance to HIV infection and to the progression to AIDS.
Immune dysregulation in human immunodeficiency virus infection: know it, fix it, prevent it?
Authors: Boasso A. , Shearer G. M. , Chougnet C. 
Published: December 2008

Abstract.Infection of humans by the human immunodeficiency virus (HIV) causes a progressive, multifactorial impairment of the immune system eventually leading to the acquired immunodeficiency syndrome (AIDS). No cure or vaccine exists yet against HIV infection. More worrisome is the fact that despite having identified HIV as the cause of the AIDS, we still do not understand what pathogenic mechanisms lead to the debacle of the immune system. In this review we consider the extent and the limits of our knowledge of HIV pathogenesis, and how this knowledge may be used to design preventive and therapeutic approaches.
Are QST–FST comparisons for natural populations meaningful?
Authors: PUJOL B. , WILSON A. J. , ROSS R. I. C. , PANNELL J. R. 
Published: December 2008

AbstractComparisons between putatively neutral genetic differentiation amongst populations, FST, and quantitative genetic variation, QST, are increasingly being used to test for natural selection. However, we find that approximately half of the comparisons that use only data from wild populations confound phenotypic and genetic variation. We urge the use of a clear distinction between narrow‐sense QST, which can be meaningfully compared with FST, and phenotypic divergence measured between populations, PST, which is inadequate for comparisons in the wild. We also point out that an unbiased estimate of QST can be found using the so‐called ‘animal model’ of quantitative genetics.
Can clone size serve as a proxy for clone age?An exploration using microsatellite divergence in Populus tremuloides
Authors: ALLY D. , RITLAND K. , OTTO S. P. 
Published: December 2008

AbstractIn long‐lived clonal plants, the overall size of a clone is often used to estimate clone age. The size of a clone, however, might be largely determined by physical or biotic interactions, obscuring the relationship between clone size and age. Here, we use the accumulation of mutations at 14 microsatellite loci to estimate clone age in trembling aspen (Populus tremuloides) from southwestern Canada. We show that the observed patterns of genetic divergence are consistent with a model of increasing ramet population size, allowing us to use pairwise genetic divergence as an estimator of clone age. In the populations studied, clone size did not exhibit a significant relationship with microsatellite divergence, indicating that clone size is not a good proxy for clone age. In P. tremuloides, the per‐locus per‐year neutral somatic mutation rate across 14 microsatellite loci was estimated to lie between 6 × 10−7 (lower bound) and 4 × 10−5 (upper bound).
Somatic mutations as a useful tool for studying clonal dynamics in trees
Authors: HEINZE BERTHOLD , FUSSI BARBARA 
Published: December 2008

AbstractThe seemingly eternal cycles of clonal growth in many tree species, with members of Populus (aspen, poplars, cottonwoods and the like) featuring most prominently, provoke a number of questions on the interface between ecology, genetics and forestry. In this issue, two groups present their approaches to clonal dynamics (Ally et al. 2008 and Mock et al. 2008), using microsatellite (or simple sequence repeat, SSR) variation in P. tremuloides. Ally et al. developed and applied a model for using microsatellites to estimate clone age and infer other community characteristics. Mock et al. used fewer microsatellites but in more individuals, to examine clone size and distribution across the landscape.