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Long-term Increase (long-term + increase)
Selected AbstractsLong-term increase in liver volume after Denver peritoneovenous shunt: report of two casesLIVER INTERNATIONAL, Issue 5 2009Hisamitsu Miyaaki No abstract is available for this article. [source] Long-term increase in nitrogen supply alters above- and below-ground ectomycorrhizal communities and increases the dominance of Russula spp. in a temperate oak savannaNEW PHYTOLOGIST, Issue 1 2003Peter G. Avis Summary ,,Here we examine the effects of increased nitrogen (N) supply on the ectomycorrhizal fungal communities of a temperate oak savanna. ,,In a 16-yr N-addition experiment in which replicate 1000 m2 plots received 0, 5.4 or 17 g N m,2 yr,1, ectomycorrhizal sporocarp production was measured in the 14th, 15th and 16th year of fertilization. Ectomycorrhizal fungi (EMF) colonizing roots were examined by morphotyping-PCR-RFLP and sequence analysis in the 14th and 15th year of fertilization. ,,Total sporocarp richness was reduced by > 50% in both fertilization treatments in all 3 yrs, whereas Russula spp. produced approx. five times more sporocarps with 17 g N m,2 yr,1. Below-ground, treatment-scale species richness and species area curves were lower with 17 g N m,2 yr,1 but richness, diversity indices and evenness at smaller spatial scales were not. Dominant fungi colonizing roots included Cenococcum geophilum, common in all treatments, Cortinarius spp., dominant in unfertilized plots, and Russula spp., dominant with 17 g N m,2 yr,1. ,,Communities of EMF in this temperate deciduous ecosystem responded to N addition similarly to those of coniferous ecosystems in that increased N supply altered EMF diversity and community composition but differently in that dominance of Russula spp. increased. [source] The myth of plant species saturationECOLOGY LETTERS, Issue 4 2008Thomas J. Stohlgren Abstract Plant species assemblages, communities or regional floras might be termed ,saturated' when additional immigrant species are unsuccessful at establishing due to competitive exclusion or other inter-specific interactions, or when the immigration of species is off-set by extirpation of species. This is clearly not the case for state, regional or national floras in the USA where colonization (i.e. invasion by exotic species) exceeds extirpation by roughly a 24 to 1 margin. We report an alarming temporal trend in plant invasions in the Pacific Northwest over the past 100 years whereby counties highest in native species richness appear increasingly invaded over time. Despite the possibility of some increased awareness and reporting of native and exotic plant species in recent decades, historical records show a significant, consistent long-term increase in exotic species (number and frequency) at county, state and regional scales in the Pacific Northwest. Here, as in other regions of the country, colonization rates by exotic species are high and extirpation rates are negligible. The rates of species accumulation in space in multi-scale vegetation plots may provide some clues to the mechanisms of the invasion process from local to national scales. [source] Rapid and long-term alterations of hippocampal GABAB receptors in a mouse model of temporal lobe epilepsyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003Andrea Straessle Abstract Alterations of ,-aminobutyric acid (GABA)B receptor expression have been reported in human temporal lobe epilepsy (TLE). Here, changes in regional and cellular expression of the GABAB receptor subunits R1 (GBR1) and R2 (GBR2) were investigated in a mouse model that replicates major functional and histopathological features of TLE. Adult mice received a single, unilateral injection of kainic acid (KA) into the dorsal hippocampus, and GABAB receptor immunoreactivity was analysed between 1 day and 3 months thereafter. In control mice, GBR1 and GBR2 were distributed uniformly across the dendritic layers of CA1,CA3 and dentate gyrus. In addition, some interneurons were labelled selectively for GBR1. At 1 day post-KA, staining for both GBR1 and GBR2 was profoundly reduced in CA1, CA3c and the hilus, and no interneurons were visible anymore. At later stages, the loss of GABAB receptors persisted in CA1 and CA3, whereas staining increased gradually in dentate gyrus granule cells, which become dispersed in this model. Most strikingly, a subpopulation of strongly labelled interneurons reappeared, mainly in the hilus and CA3 starting at 1 week post-KA. In double-staining experiments, these cells were selectively labelled for neuropeptide Y. The number of GBR1-positive interneurons also increased contralaterally in the hilus. The rapid KA-induced loss of GABAB receptors might contribute to epileptogenesis because of a reduction in both presynaptic control of transmitter release and postsynaptic inhibition. In turn, the long-term increase in GABAB receptors in granule cells and specific subtypes of interneurons may represent a compensatory response to recurrent seizures. [source] The microfood web of grassland soils responds to a moderate increase in atmospheric CO2GLOBAL CHANGE BIOLOGY, Issue 7 2005Ilja Sonnemann Abstract The response of the soil microfood web (microflora, nematodes) to a moderate increase in atmospheric CO2 (+20%) was investigated by means of a free air CO2 enrichment experiment. The study was carried out in a seminatural temperate grassland for a period of 4 consecutive years (1 year before fumigation commenced and 3 years with fumigation). Several soil biological parameters showed no change (microbial biomass, bacterial biomass) or decline (microbial respiration) in the first year of elevated CO2 treatment as compared with controls. Each of these parameters were higher than controls, however, after 3 years of treatment. The relative abundance of predaceous nematodes also decreased in year 1 of the experiment, increased in year 2, but decreased again in year 3. In contrast, the relative abundance of root hair feeding nematodes, at first, increased under elevated CO2 and then returned to the initial level again. Increased microbial biomass indicates enhanced C storage in the labile carbon pool of the active microfood web in subsequent years. According to measurements on the amounts of soil extractable C, changes in resource availability seem to be key to the response of the soil microfood web. We found a strong response of bacteria to elevated CO2, while the fungal biomass remained largely unchanged. This contrasts to findings reported in the literature. We hypothesize that this may be because of contrasting effects of different levels of CO2 enrichment on the microbial community (i.e. stimulation of bacteria at moderate levels and stimulation of fungi at high levels of CO2 enrichment). However, various CO2 effects observed in our study are similar in magnitude to those observed in other studies for a much higher level of atmospheric carbon. These include the particular sensitivity of predaceous nematodes and the long-term increase of microbial respiration. Our findings confirm that the potential of terrestrial ecosystems to accumulate additional carbon might be lower than previously thought. Furthermore, CO2 -induced changes of temperate grassland ecosystems might emerge much earlier than expected. [source] HISTALP,historical instrumental climatological surface time series of the Greater Alpine RegionINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2007Ingeborg Auer This paper describes the HISTALP database, consisting of monthly homogenised records of temperature, pressure, precipitation, sunshine and cloudiness for the ,Greater Alpine Region' (GAR, 4,19°E, 43,49°N, 0,3500m asl). The longest temperature and air pressure series extend back to 1760, precipitation to 1800, cloudiness to the 1840s and sunshine to the 1880s. A systematic QC procedure has been applied to the series and a high number of inhomogeneities (more than 2500) and outliers (more than 5000) have been detected and removed. The 557 HISTALP series are kept in different data modes: original and homogenised, gap-filled and outlier corrected station mode series, grid-1 series (anomaly fields at 1° × 1°, lat × long) and Coarse Resolution Subregional (CRS) mean series according to an EOF-based regionalisation. The leading climate variability features within the GAR are discussed through selected examples and a concluding linear trend analysis for 100, 50 and 25-year subperiods for the four horizontal and two altitudinal CRSs. Among the key findings of the trend analysis is the parallel centennial decrease/increase of both temperature and air pressure in the 19th/20th century. The 20th century increase (+1.2 °C/+ 1.1 hPa for annual GAR-means) evolved stepwise with a first peak near 1950 and the second increase (1.3 °C/0.6hPa per 25 years) starting in the 1970s. Centennial and decadal scale temperature trends were identical for all subregions. Air pressure, sunshine and cloudiness show significant differences between low versus high elevations. A long-term increase of the high-elevation series relative to the low-elevation series is given for sunshine and air pressure. Of special interest is the exceptional high correlation near 0.9 between the series on mean temperature and air pressure difference (high-minus low-elevation). This, further developed via some atmospheric statics and thermodynamics, allows the creation of ,barometric temperature series' without use of the measures of temperature. They support the measured temperature trends in the region. Precipitation shows the most significant regional and seasonal differences with, e.g., remarkable opposite 20th century evolution for NW (9% increase) versus SE (9% decrease). Other long- and short-term features are discussed and indicate the promising potential of the new database for further analyses and applications. Copyright © 2006 Royal Meteorological Society. [source] The Ordovician Biodiversification: revolution in the oceanic trophic chainLETHAIA, Issue 2 2008THOMAS SERVAIS The Early Palaeozoic phytoplankton (acritarch) radiation paralleled a long-term increase in sea level between the Early Cambrian and the Late Ordovician. In the Late Cambrian, after the SPICE ,13Ccarb excursion, acritarchs underwent a major change in morphological disparity and their taxonomical diversity increased to reach highest values during the Middle Ordovician (Darriwilian). This highest phytoplankton diversity of the Palaeozoic was possibly the result of palaeogeography (greatest continental dispersal) and major orogenic and volcanic activity, which provided maximum ecospace and large amounts of nutrients. With its warm climate and high atmospheric CO2 levels, the Ordovician was similar to the Cretaceous: a period when phytoplankton diversity was at its maximum during the Mesozoic. With increased phytoplankton availability in the Late Cambrian and Ordovician a radiation of zooplanktonic organisms took place at the same time as a major diversification of suspension feeders. In addition, planktotrophy originated in invertebrate larvae during the Late Cambrian,Early Ordovician. These important changes in the trophic chain can be considered as a major palaeoecological revolution (part of the rise of the Palaeozoic Evolutionary Fauna of Sepkoski). There is now sufficient evidence that this trophic chain revolution was related to the diversification of the phytoplankton, of which the organic-walled fraction is partly preserved. [source] Changes in blink reflex excitability after globus pallidus internus stimulation for dystoniaMOVEMENT DISORDERS, Issue 10 2006Stephen Tisch MBBS Abstract A pathophysiological feature of dystonia is reduced inhibition at various levels of the nervous system, which may be detected in clinically unaffected body parts. Chronic deep brain stimulation (DBS) of the globus pallidus internus (GPi) has emerged as an effective treatment for primary torsion dystonia (PTD), although its mechanism of action and impact on inhibitory abnormalities in dystonia are unknown. We sought to understand the effect of GPi DBS on brainstem excitability in patients with PTD. We measured the blink reflex from orbicularis oculi in response to paired electrical stimulation of the supraorbital nerve at interstimulus intervals of 500 and 1,000 milliseconds in 10 patients with PTD before and at intervals of 1, 3, and 6 months after bilateral GPi DBS and in 10 healthy subjects. Patients were clinically evaluated using the Burke,Fahn,Marsden dystonia rating scale. We found R2 inhibition was significantly decreased in PTD patients compared with control subjects and progressively increased after GPi DBS, which correlated with clinical improvement in dystonia. We conclude that GPi DBS for PTD results in functional reorganization of the nervous system, which includes a long-term increase in brainstem inhibition. © 2006 Movement Disorder Society [source] Derangement of Heart Rate Variability During a Catastrophic Earthquake: A Possible Mechanism for Increased Heart AttacksPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2001LIAN-YU LIN LIN, L.-Y., et al.: Derangement of Heart Rate Variability During a Catastrophic Earthquake: A Possible Mechanism for Increased Heart Attacks. At 1:47 AM on September 21, 1999, the middle part of Taiwan was struck by a major earthquake measuring 7.3 on the Richter scale. It has been shown that the mental stress caused by an earthquake could lead to a short- or long-term increase in frequency of cardiac death probably through activation of the sympathetic nervous system. The aim of this study was to investigate the effects of emotional stress on the autonomic system during an actual earthquake. Fifteen patients receiving a 24-hour Holter ECG study starting from 10 ± 4 hours before the onset of the earthquake were included for the analysis of time- and frequency-domains of heart rate variability (HRV) at several time periods. A 24-hour Holter study recorded 2,6 months before the earthquake in 30 age- and sex-matched subjects served as the control group. Heart rate and the low frequency (LF) to high frequency (HF) ratio increased significantly after the earthquake and were attributed mainly to the withdrawal of the high frequency component (parasympathetic activity) of HRV. Sympathetic activation was blunted in elderly subjects > 60 years old. The concomitant ST-T depression observed in the Holter study correlated with a higher increment of LF as compared to HF components. The changes observed in HRV recovered completely 40 minutes following the earthquake. The derangement of HRV results from the withdrawal of the parasympathetic component and the arousal of sympathetic activity by the stressful earthquake. However, this autonomic derangement returned towards normal 40 minutes following the earthquake. [source] Restoration of C4 grasses with seasonal fires in a C3/C4 grassland invaded by Prosopis glandulosa, a fire-resistant shrubAPPLIED VEGETATION SCIENCE, Issue 4 2010R. James Ansley Abstract Questions: Can prescribed fire restore C4 perennial grasses in grassland ecosystems that have become dominated by fire-resistant C3 shrubs (Prosopis glandulosa) and C3 grasses? Do fires in different seasons alter the direction of change in grass composition? Location: Texas, USA. Methods: We quantified short- and long-term (12 yr post-fire) herbaceous functional group cover and diversity responses to replicated seasonal fire treatments: (1) repeated-winter fires (three in 5 yr), (2) repeated-summer fires (two in 3 yr), and (3) alternate-season fires (two winter and one summer in 4 yr), compared with a no-fire control. Results: Summer fires were more intense than winter fires, but all fire treatments temporarily decreased Prosopis and C3 annual grass cover. The alternate-season fire treatment caused a long-term increase in C4 mid-grass cover and functional group diversity. The repeated-summer fire treatment increased C4 short-grass cover but also caused a long-term increase in bare ground. The repeated winter fire treatment had no long-term effects on perennial grass cover. Mesquite post-fire regrowth had increasingly negative impacts on herbaceous cover in all fire treatments. Conclusions: Summer fire was necessary to shift herbaceous composition toward C4 mid-grasses. However, the repeated-summer fire treatment may have been too extreme and caused post-fire herbaceous composition to "over-shift" toward less productive C4 short-grasses rather than C4 mid-grasses. This study provides some of the first long-term data showing a possible benefit of mixing seasonal fires (i.e., the alternate-season fire treatment) in a prescribed burning management plan to restore C4 mid-grass cover and enhance overall herbaceous diversity. [source] Effects of 20-hydroxyecdysone and juvenile hormone on octopamine metabolism in females of DrosophilaARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2009E. V. Bogomolova Abstract The effect of exogenous 20-hydroxyecdysone (20E) and juvenile hormone (JH) on the activities of the tyrosine decarboxylase (TDC), the first enzyme in octopamine (OA) synthesis, has been studied in young females of wild type D. virilis and D. melanogaster under normal and heat stress (38°C) conditions. Flies fed 20E expressed increased TDC activity in both species. JH application decreased TDC activity in both species. A rise in JH and 20E levels did not prevent a TDC response to heat stress, but changed the response intensity. A long-term increase in JH titre had no effect on the activity of main OA catabolyzing enzyme, arylalkylamine N-acetyltransferase, in females of both species. A possible mechanism of regulation of OA levels by 20E and JH in Drosophila females is discussed. © 2009 Wiley Periodicals, Inc. [source] Morphology and origin of major Cenozoic sequence boundaries in the eastern North Sea Basin: top Eocene, near-top Oligocene and the mid-Miocene unconformityBASIN RESEARCH, Issue 1 2001M. Huuse Unconformities in sedimentary successions (i.e. sequence boundaries) form in response to the interplay between a variety of factors such as eustasy, climate, tectonics and basin physiography. Unravelling the origin of sequence boundaries is thus one of the most pertinent questions in the analysis of sedimentary basins. We address this question by focusing on three of the most marked physical discontinuities (sequence boundaries) in the Cenozoic North Sea Basin: top Eocene, near-top Oligocene and the mid-Miocene unconformity. The Eocene/Oligocene transition is characterized by an abrupt increase in sediment supply from southern Norway and by minor erosion of the basin floor. The near-top Oligocene and the mid-Miocene unconformity are characterized by major changes in sediment input directions and by widespread erosion along their clinoform breakpoints. The mid-Miocene shift in input direction was followed by a marked increase in sediment supply to the southern and central North Sea Basin. Correlation with global ,18O records suggests that top Eocene correlates with a major long-term ,18O increase (inferred climatic cooling and eustatic fall). Near-top Oligocene does not correlate with any major ,18O events, while the mid-Miocene unconformity correlates with a gradual decrease followed by a major long-term increase in ,18O values The abrupt increases in sediment supply in post-Eocene and post-middle Miocene time correlate with similar changes worldwide and with major ,18O increases, suggesting a global control (i.e. climate and eustasy) of the post-Eocene sedimentation in the North Sea Basin. Erosional features observed at near-top Oligocene and at the mid-Miocene unconformity are parallel to the clinoform breakpoints and resemble scarps formed by mass wasting. Incised valleys have not been observed, indicating that sea level never fell significantly below the clinoform breakpoint during the Oligocene to middle Miocene. [source] Genetic loss of D-amino acid oxidase activity reverses schizophrenia-like phenotypes in miceGENES, BRAIN AND BEHAVIOR, Issue 1 2010V. Labrie Reduced function of the N -methyl- d -aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. The NMDAR contains a glycine binding site in its NR1 subunit that may be a useful target for the treatment of schizophrenia. In this study, we assessed the therapeutic potential of long-term increases in the brain levels of the endogenous NMDAR glycine site agonist D-serine, through the genetic inactivation of its catabolic enzyme D-amino acid oxidase (DAO) in mice. The effects of eliminating DAO function were investigated in mice that display schizophrenia-related behavioral deficits due to a mutation (Grin 1D481N) in the NR1 subunit that results in a reduction in NMDAR glycine affinity. Grin 1D481N mice show deficits in sociability, prolonged latent inhibition, enhanced startle reactivity and impaired spatial memory. The hypofunctional Dao 1G181R mutation elevated brain levels of D-serine, but alone it did not affect performance in the behavioral measures. Compared to animals with only the Grin 1D481N mutation, mice with both the Dao1G181R and Grin 1D481N mutations displayed an improvement in social approach and spatial memory retention, as well as a reversal of abnormally persistent latent inhibition and a partial normalization of startle responses. Thus, an increased level of D-serine resulting from decreased catalysis corrected the performance of mice with deficient NMDAR glycine site activation in behavioral tasks relevant to the negative and cognitive symptoms of schizophrenia. Diminished DAO activity and elevations in D-serine may serve as an effective therapeutic intervention for the treatment of psychiatric symptoms. [source] Coupling Short-Term Changes in Ambient UV-B levels with Induction of UV-Screening Compounds,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Joe H. Sullivan ABSTRACT A substantial number of studies have been conducted over the last several decades to assess the potential impacts of long-term increases in ultraviolet-B radiation (UV-B between 280 and 320 nm) that will result from continued depletion of stratospheric ozone. However, seasonal changes, tropospheric chemistry and cloudiness are the dominant factors controlling ambient UV-B levels on a short-term or daily basis. The effects of short-term changes in UV-B on plant growth, phytochemistry and physiological processes have received relatively little attention. The USDA UV-B Monitoring and Research Program provides an excellent network of stations that provide an opportunity to monitor long-term changes in solar UV-B radiation and evaluate the responses of plants to short-term variation in UV-B levels on a near-real-time basis. In this study barley (Hordeum vulgare L.) and soybean (Glycine max [L] Merr.) were used as model systems. Emerging seedlings of these species were grown under either near-ambient levels of UV-B or under reduced levels (ca 90% reduction) in the field. Periodic measurements of foliar UV-screening compounds were made on separate groups of seedlings planted at intervals over the growing season during contrasting periods of ambient levels of UV radiation. The levels of UV-screening compounds correlated with UV-B levels in both species and with UV-A in soybean but the sensitivity of the response differed between the two species and among the soybean cultivars. Response differences among species may be related to unique secondary chemistry of each species, so one response estimate or action spectrum may not be appropriate for all species. [source] Long-term trends in cancer mortality in the United States, 1930,1998,CANCER, Issue S12 2003M.S., Phyllis A. Wingo Ph.D. Abstract BACKGROUND Progress against cancer can be examined by analyzing long-term trends in cancer incidence and mortality. The recent directive from the U.S. Department of Health and Human Services to adopt the 2000 U.S. standard population for the age adjustment of death rates prompted the American Cancer Society to update historical cancer mortality statistics using the new standard. METHODS Mortality data were abstracted by race, gender, year, and age at death for 1930 through 1959 from annual volumes of Vital Statistics of the United States. For 1960 through 1998, these data were obtained from data tapes provided by the National Center for Health Statistics. Two U.S. standard million populations (1970 and 2000) were used to calculate age-adjusted rates. Average annual percent change was estimated for each decade by site, gender, and age, and the statistical significance of the change was assessed at p < 0.05. RESULTS After long-term increases or mostly level trends that date from the 1930s for some sites, death rates for cancers of the lung (in males), prostate, female breast, colon-rectum, pancreas, leukemia, and ovary were decreasing in the 1990s. Liver cancer death rates were increasing in the 1990s. Throughout the study period, death rates for female lung cancer increased, while death rates for stomach and uterine cancers declined. CONCLUSIONS The trends of decreasing cancer death rates for the leading cancer sites in the 1990s are encouraging. However, surveillance researchers must continue to monitor these declines to assess whether the progress seen in this decade persists. Efforts also must be made to study the sites with increasing trends and identify potential underlying causes. Cancer 2003;97(12 Suppl):3133,3275. Published 2003 by the American Cancer Society. DOI 10.1002/cncr.11380 [source] | ||||||||||||||||