bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective spatiotemporal induction of matrix metalloproteinase-2 and matrix metalloproteinase-9 transcription after myocardial infarction
Authors: Mukherjee Rupak , Mingoia Joseph T. , Bruce James A. , Austin Jeffrey S. , Stroud Robert E. , Escobar G. Patricia , McClister David M. , Allen Claire M. , Alfonso-Jaume Maria A. , Fini M. Elizabeth , Lovett David H. , Spinale Francis G.
Published: June 2006

Myocardial remodeling after myocardial infarction (MI) is associated with increased levels of the matrix metalloproteinases (MMPs). Levels of two MMP species, MMP-2 and MMP-9, are increased after MI, and transgenic deletion of these MMPs attenuates post-MI left ventricular (LV) remodeling. This study characterized the spatiotemporal patterns of gene promoter induction for MMP-2 and MMP-9 after MI. MI was induced in transgenic mice in which the MMP-2 or MMP-9 promoter sequence was fused to the β-galactosidase reporter, and reporter level was assayed up to 28 days after MI. Myocardial localization with respect to cellular sources of MMP-2 and MMP-9 promoter induction was examined. After MI, LV diameter increased by 70% ( P < 0.05), consistent with LV remodeling. β-Galactosidase staining in MMP-2 reporter mice was increased by 1 day after MI and increased further to 64 ± 6% of LV epicardial area by 7 days after MI ( P < 0.05). MMP-2 promoter activation occurred in fibroblasts and myofibroblasts in the MI region. In MMP-9 reporter mice, promoter induction was detected after 3 days and peaked at 7 days after MI (53 ± 6%, P < 0.05) and was colocalized with inflammatory cells at the peri-infarct region. Although MMP-2 promoter activation was similarly distributed in the MI and border regions, activation of the MMP-9 promoter was highest at the border between the MI and remote regions. These unique findings visually demonstrated that activation of the MMP-2 and MMP-9 gene promoters occurs in a distinct spatial relation with reference to the MI region and changes in a characteristic time-dependent manner after MI.
Acidic fibroblast growth factor decreases α-smooth muscle actin expression and induces apoptosis in human normal lung fibroblasts
Authors: Ramos Carlos , Montaño Martha , Becerril Carina , Cisneros-Lira José , Barrera Lourdes , Ruíz Victor , Pardo Annie , Selman Moisés
Published: June 2006

Fibroblast/myofibroblast expansion is critical in the pathogenesis of pulmonary fibrosis. To date, most research has focused on profibrotic mediators, whereas studies on antifibrotic factors are scanty. In this study, we explored the effects of acidic fibroblast growth factor (FGF-1) and FGF-1 plus heparin (FGF-1+H) on fibroblast growth rate, apoptosis, and myofibroblast differentiation. Heparin was used because it participates in FGF-1 signaling. Growth rate was evaluated by WST-1 colorimetric assay, DNA synthesis by [3H]thymidine incorporation, and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and cleaved caspase 3. Expression of α-smooth muscle actin (α-SMA) was examined by immunocytochemistry, flow cytometry, real-time PCR, and immunoblotting. Despite the induction of DNA synthesis, FGF-1+H significantly reduced fibroblast growth rate. This correlated with a significant increase in apoptosis, evaluated by TUNEL (41.6 ± 1.4% vs. 12.5 ± 0.6% from controls; P < 0.01) and cleaved caspase 3 (295 ± 32 vs. 200 ± 19 ng/106cells from controls; P < 0.05). Double immunostaining (α-SMA-TUNEL) revealed that the levels of induced apoptosis were similar in fibroblasts and myofibroblasts. FGF-1+H inhibited the effect of TGF-β1 on myofibroblast differentiation. α-SMA-positive cells were reduced by immunocytochemistry from 44.5 ± 6.5% to 10.9 ± 1.9% and by flow cytometry from 30.6 ± 2.5% to 7.7 ± 0.6% ( P < 0.01). Also, FGF-1+H significantly inhibited the TGF-β1 induction of α-SMA quantified by real-time PCR and Western blot. This decrease was associated with a 35% reduction in TGF-β1-induced collagen gel contraction. The effect of FGF-1+H was mediated by a significant decrease of TGF-β1-induced Smad2 phosphorylation. FGF-1 alone exhibited similar but lower effects. These findings suggest that FGF-1 can have an antifibrogenic role, inducing apoptosis of fibroblasts and inhibiting myofibroblast differentiation.
Smooth muscle myosin isoform expression and LC20phosphorylation in innate rat airway hyperresponsiveness
Authors: Gil Fulvio R. , Zitouni Nedjma B. , Azoulay Eric , Maghni Karim , Lauzon Anne-Marie
Published: June 2006

Four smooth muscle myosin heavy chain (SMMHC) isoforms are generated by alternative mRNA splicing of a single gene. Two of these isoforms differ by the presence [(+)insert] or absence [(−)insert] of a 7-amino acid insert in the motor domain. The rate of actin filament propulsion of the (+)insert SMMHC isoform, as measured in the in vitro motility assay, is twofold greater than that of the (−)insert isoform. We hypothesized that a greater expression of the (+)insert SMMHC isoform and greater regulatory light chain (LC20) phosphorylation contribute to airway hyperresponsiveness. We measured airway responsiveness to methacholine in Fischer hyperresponsive and Lewis normoresponsive rats and determined SMMHC isoform mRNA and protein expression, as well as essential light chain (LC17) isoforms, h-caldesmon, and α-actin protein expression in their tracheae. We also measured tracheal muscle strip contractility in response to methacholine and corresponding LC20phosphorylation. We found Fischer rats have more (+)insert mRNA (69.4 ± 2.0%) (mean ± SE) than Lewis rats (53.0 ± 2.4%; P < 0.05) and a 44% greater content of (+)insert isoform relative to total myosin protein. No difference was found for LC17isoform, h-caldesmon, and α-actin expression. The contractility experiments revealed a greater isometric force for Fischer trachealis segments (4.2 ± 0.8 mN) than Lewis (1.9 ± 0.4 mN; P < 0.05) and greater LC20phosphorylation level in Fischer (55.1 ± 6.4) than in Lewis (41.4 ± 6.1; P < 0.05) rats. These results further support the contention that innate airway hyperresponsiveness is a multifactorial disorder in which increased expression of the fast (+)insert SMMHC isoform and greater activation of LC20lead to smooth muscle hypercontractility.
The transcriptional response to lipopolysaccharide reveals a role for interferon-γ in lung neutrophil recruitment
Authors: Burch Lauranell H. , Yang Ivana V. , Whitehead Gregory S. , Chao Frank G. , Berman Katherine G. , Schwartz David A.
Published: June 2006

Neutrophil recruitment to the lung after lipopolysaccharide (LPS; endotoxin) inhalation is primarily dependent on Toll-like receptor 4 (Tlr4) signaling, because it is virtually absent in mice deficient in Tlr4. However, among strains wild type for Tlr4, the magnitude of neutrophil recruitment to the lung after LPS inhalation is variable, suggesting the involvement of genes other than Tlr4. To identify genes associated with the inflammatory response to inhaled LPS, we evaluated the transcriptional response in lungs of 12 inbred strains of mice, 8 which are wild type for Tlr4 and 4 of which lack functional Tlr4. Using the promoter integration in microarray analysis algorithm, we scanned our gene list for transcription factor-binding sites significantly overrepresented among Tlr4 wild-type strains with high neutrophil influx in the lung after LPS inhalation. This analysis identified the interferon (IFN)-stimulated response element (ISRE) as the most overrepresented transcription factor (present in 24% of the promoters) associated with the neutrophil influx to the lower respiratory tract. To test the validity of this observation, we evaluated IFN-γ-deficient mice and found that the presence of IFN-γ is essential for robust neutrophil recruitment to the lower respiratory tract and modulation of key regulatory cytokines and chemokines after LPS inhalation. In conclusion, using a genomic approach, we identified the ISRE as a transcriptional element associated with the neutrophil response to inhaled LPS and demonstrated for the first time that IFN-γ plays a critical role in LPS-induced neutrophil recruitment to the lower airways.
HIF-1 regulates hypoxic induction of NHE1 expression and alkalinization of intracellular pH in pulmonary arterial myocytes
Authors: Shimoda Larissa A. , Fallon Michele , Pisarcik Sarah , Wang Jian , Semenza Gregg L.
Published: June 2006

Vascular remodeling resulting from altered pulmonary arterial smooth muscle cell (PASMC) growth is a contributing factor to the pathogenesis of hypoxic pulmonary hypertension. PASMC growth requires an alkaline shift in intracellular pH (pHi) and we previously showed that PASMCs isolated from mice exposed to chronic hypoxia exhibited increased Na+/H+exchanger (NHE) expression and activity, which resulted in increased pHi. However, the mechanism by which hypoxia caused these changes was unknown. In this study we tested the hypothesis that hypoxia-induced changes in PASMC pH homeostasis are mediated by the transcriptional regulator hypoxia-inducible factor 1 (HIF-1). Consistent with previous results, increased NHE isoform 1 (NHE1) mRNA and protein, enhanced NHE activity, and an alkaline shift in pHiwere observed in PASMCs isolated from wild-type mice exposed to chronic hypoxia (3 wk at 10% O2). In contrast, these changes were absent in PASMCs isolated from chronically hypoxic mice with partial deficiency for HIF-1. Exposure of PASMCs to hypoxia ex vivo (48 h at 4% O2) or overexpression of HIF-1 in the absence of hypoxia also increased NHE1 mRNA and protein expression. Our results indicate that full expression of HIF-1 is essential for hypoxic induction of NHE1 expression and changes in PASMC pH homeostasis and suggest a novel mechanism by which HIF-1 mediates pulmonary vascular remodeling during the pathogenesis of hypoxic pulmonary hypertension.
The Virtual Site Museum: A Multi-Purpose, Authoritative, and Functional Virtual Heritage Resource
Authors: Kim Young-Seok , Kesavadas Thenkurussi , Paley Samuel M
Published: June 2006

The Virtual Site Museum is an interactive virtual reality interface for various purposes including archaeological research, education, and public demonstration. Its virtual environment contains precise, authoritative, and integrated archaeological and historical files culled from published and unpublished excavation records and the various art museums, which preserve artifacts from the real archaeological site. Running in real-time, it provides full-body immersion, 3D ancient figure animation, and a virtual artifacts interface and corresponding user-oriented interactions in a functional virtual environment. The first of the sites to be documented in the Virtual Site Museum was the Northwest Palace of King Ashurnasirpal II (883–859 bc), located in northeastern Iraq, a famous Assyrian world heritage archaeological site. In this paper we describe how we applied Virtual Reality (VR) to a cultural heritage in peril, and how we are adapting previously generated PC versions to UNIX platforms. We also explain our experiences and achievements in archaeological research and classroom accessibility.
The Demographics, Motivations, and Derived Experiences of Users of Massively Multi-User Online Graphical Environments
Authors: Yee Nick
Published: June 2006

Online survey data were collected from 30,000 users of Massively Multi-User Online Role-Playing Games (MMORPGs) over a three year period to explore users' demographics, motivations, and derived experiences. Not only do MMORPGs appeal to a broad age range (Mage = 26.57, range = 11–68), but the appeal is strong (on average 22 hours of usage per week) across users of all ages (r = −.04). An exploratory factor analysis revealed a five factor model of user motivations—Achievement, Relationship, Immersion, Escapism, and Manipulation—illustrating the multifaceted appeal of these online environments. Male players were significantly more likely to be driven by the Achievement and Manipulation factors, while female players were significantly more likely to be driven by the Relationship factor. Also, the data indicated that users derived meaningful relationships and salient emotional experiences, as well as real-life leadership skills from these virtual environments. MMORPGs are not simply a pastime for teenagers, but a valuable research venue and platform where millions of users interact and collaborate using real-time 3D avatars on a daily basis.
Aspen the Verb: Musings on Heritage and Virtuality
Authors: Naimark Michael
Published: June 2006

Aspen, the picturesque mountain town in Colorado, is known for two processes, or “verbs,” relating to heritage and virtuality. One is to “moviemap,” the process of rigorously filming path and turn sequences to simulate interactive travel and to use as a spatial interface for a multimedia database. The other is to “Aspenize,” the process by which a fragile cultural ecosystem is disrupted by tourism and growth. This essay reflects on their significance and describes exemplary work integrating these two seemingly disparate concepts.
Enhancing Virtual Reality with Artificial Life: Reconstructing a Flooded European Mesolithic Landscape
Authors: Ch'ng Eugene , Stone Robert J
Published: June 2006

The fusion of Virtual Reality and Artificial Life technologies has opened up a valuable and effective technique for research in the field of dynamic archaeological reconstruction. This paper describes early evaluations of simulated vegetation and environmental models using decentralized Artificial Life entities. The results demonstrate a strong feasibility for the application of integrated VR and Artificial Life in solving a 10,000 year old mystery shrouding a submerged landscape in the Southern North Sea, off the east coast of the United Kingdom. Three experimental scenarios with dynamic, “artificial” vegetation are observed to grow, reproduce, and react to virtual environmental parameters in a way that mimics their physical counterparts. Through further experimentation and refinement of the Artificial Life rules, plus the integration of additional knowledge from subject matter experts in related scientific fields, a credible reconstruction of the ancient and, today, inaccessible landscape may be within our reach.
The Influence of Spatial Delocation on Perceptual Integration of Vision and Touch
Authors: Congedo Marco , Lécuyer Anatole , Gentaz Edouard
Published: June 2006

How do we perceive objects when what we see and what we touch is not at the same place? In a virtual environment, we observed that spatial delocation promotes visual dominance when judging the rotation angle of a hand-operated handle. Thus, the delocation of perceptual information appears to increase considerably the weight of the dominant sense at the expense of the other. We relate this result to the design of teleoperation and virtual reality systems, in which, typically, the visual and haptic sensory information originates in spatially distinct devices.
Prefix-querying with an L1 distance metric for time-series subsequence matching under time warping
Authors: Park Sanghyun , Kim Sang-Wook
Published: June 2006

This paper discusses the way of processing time-series subsequence matching under time warping. Time warping enables sequences to be found with similar patterns even when they are of different lengths. The prefix-querying method is the first index-based approach that efficiently performs time-series subsequence matching under time warping without false dismissals. This method employs the L distance metric as a base distance function so as to allow users to issue queries conveniently. In this paper, we extend the prefix-querying method for absorbing L1, which is the most widely used as a base distance function in time-series subsequence matching under time warping, instead of L. We formally prove that the prefix-querying method with the L1 distance metric does not incur any false dismissals in the subsequence matching. To show its superiority, we conduct performance evaluation via a variety of experiments. The results reveal that our method achieves significant performance improvement over the previous methods, up to 10.7 times, with a data set containing real-world Korean stock data sequences, and up to 180 times with data sets containing a very large volume of synthetic data sequences.
Watching me, watching you: privacy attitudes and reactions to identity card implementation scenarios in the United Kingdom
Authors: Joinson Adam N. , Paine Carina , Buchanan Tom , Reips Ulf-Dietrich
Published: June 2006

In the United Kingdom, government proposals for the introduction of an identity (ID) card have raised considerable privacy concerns. In the present research, opinions and attitudes about different ways of implementing ID cards are examined using an experimental methodology. Specifically, the level and type of compulsion and application process, and the use of a centralized database or trusted third party to hold personal information, are compared for attitudes towards ID cards. Moreover, the impact of implementation scenarios on people with different privacy concern profiles is examined. The results show that an implementation that combines high compulsion with a centralized database (the approach currently favoured by the UK Government) leads to the greatest negative shift in attitudes towards ID cards. Implementations proposed by others (e.g. the London School of Economics) show significantly less negative shift in attitudes. People’s pre-existing privacy concerns also influence their evaluation of the different implementation scenarios.
Longitudinal study of content and elements in the scientific web environment
Authors: Ortega José Luis , Aguillo Isidro , Prieto José Antonio
Published: June 2006

This work is a longitudinal study of the evolution and the state of 738 web sites at two different points in time (1997 and 2004). It tries to establish the rate of growth and decay of the web and all the web elements. To this end, the structure and the contents of these web sites are extracted through a crawler and compared at the two different moments in time. The main results confirm a growth of web content and elements in the web, although there is also a high degree of web content decay. The results suggest that in the seven-year period covered by this study the web is characterized by both strong dynamism and instability.
Prehistoric habitat stability and post-settlement habitat change in a Chesapeake Bay freshwater tidal wetland, USA
Authors: Hilgartner William B. , Brush Grace S.
Published: June 2006

Analyses of fossil seeds and pollen grains preserved in seven sediment cores and borings were combined with historical land-use records to reconstruct an 1800-yr history of Otter Point Creek (OPC), a freshwater tidal deltaic wetland in the upper Chesapeake Bay. The objectives of the study were to document the role of natural and anthropogenic disturbance on habitat development at different sites within the wetland. Fossil seeds revealed a 1500-yr period (AD 230 to 1700) of subtidal habitat stability characterized by the aquatic macrophytes Zannichellia palustris, Najas gracillima, N guadalupensis, Elodea canadensis and Vallisneria americana. Natural disturbance had little or no impact on the estuarine habitat during this time. By the early 1700s, forest clearance for agriculture and lumber during European settlement led to higher erosion rates in the watershed. This led to rapid sediment efflux and broad habitat changes along a hydrologic gradient within the estuary. The aquatic macrophytes disappeared when estuarine sedimentation rates increased from a pre-1700 mean of 0.05 cm/yr to 0.60 cm/yr after 1730-1750. As the estuary continued to fill behind a prograding delta from AD 1750 to 1950, sub-tidal species were replaced sequentially by increasingly less flood-tolerant dominants of low marsh (Zizania aquatica), middle marsh (Typha angustifolia or Leersia oryzoides), high marsh (Acorus calamus), shrub marsh (Typha latifolia and Salix nigra) and riparian forest (Acer negundo, Fraxinus pennsylvanica and Betula nigra). Habitat change progressed in pulses followed by periods of habitat stasis. The most rapid and extensive period of change occurred between 1840 and 1880, synchronous with the period of highest sedimentation rates, mid-century storms and intensive land use in the watershed. The rate and pattern of community change differed among sites where position relative to the watershed, local disturbance, and channel shifts at or adjacent to the site influenced different community pathways. A conceptual model is proposed to describe the spatial and temporal development of eastern US freshwater tidal wetland habitats, reflecting the importance of the impact of colonial deforestation.
Mid-to late-Holocene relative sea-level change in southwest Britain and the influence of sediment compaction
Authors: Edwards Robin J.
Published: June 2006

Relative sea-level changes in southwest Britain are poorly constrained because of limitations in the quality and quantity of existing geological data. As a consequence, in contrast to most other regions in the UK, it is not possible to reliably infer rates of land and sea-level change during the last few thousand years. Furthermore, geologically based sea-level reconstructions from this area display significant misfits with relative sea-level predictions based on a recent global model of the glacio-isostatic adjustment process. This paper presents a new record of relative sea-level change for the last 4000 years derived from radiocarbon-dated sea-level index points. In addition to providing information concerning the pattern and rates of late Holocene sea-level change, these data are used to evaluate the suggestion that the apparent misfits between model predictions and geological reconstructions can be satisfactorily explained as a consequence of the lowering of sea-level index points by sediment compaction. The results indicate that a simple, first-order method of decompaction based on the stratigraphic position of sea-level index points, can eliminate much of the misfit between reconstructions and predictions, and substantially reduce vertical scatter in geological data. They also suggest that the influence of compaction on sea-level data from this region may be larger than previously thought. The simple addition of reliable stratigraphic data, in combination with targeted sampling, has the potential to improve our understanding of the compaction process, and increase the utility of existing data. This is increasingly important as the partnership between geophysical modelling and geological investigation becomes more commonplace in sea-level studies around the world.
Modelling river discharge and precipitation from estuarine salinity in the northern Chesapeake Bay: application to Holocene palaeoclimate
Authors: Saenger Casey , Cronin Thomas , Thunell Robert , Vann Cheryl
Published: June 2006

Long-term chronologies of precipitation can provide a baseline against which twentieth-century trends in rainfall can be evaluated in terms of natural variability and anthropogenic influence. However, there are relatively few methods to quantitatively reconstruct palaeoprecipitation and river discharge compared with proxies of other climatic factors, such as temperature. We developed autoregressive and least squares statistical models relating Chesapeake Bay salinity to river discharge and regional precipitation records. Salinity in northern and central parts of the modern Chesapeake Bay is influenced largely by seasonal, interannual and decadal variations in Susquehanna River discharge, which in turn are controlled by regional precipitation patterns. A power regressive discharge model and linear precipitation model exhibit well-defined decadal variations in peak discharge and precipitation. The utility of the models was tested by estimating Holocene palaeoprecipitation and Susquehanna River palaeodischarge, as indicated by isotopically derived palaeosalinity reconstructions from Chesapeake Bay sediment cores. Model results indicate that the early-mid Holocene (7055-5900 yr BP) was drier than the late Holocene (1500 yr BP-present), the 'Mediaeval Warm Period' (MWP) (1200-600 yr BP) was drier than the 'Little Ice Age' (LIA) (500-100 yr BP), and the twentieth century experienced extremes in precipitation possibly associated with changes in ocean-atmosphere teleconnections.
Late-Holocene vegetation and fire history from Ferry Lake, northwestern Wisconsin, USA
Authors: Lynch Elizabeth A. , Calcote Randy , Hotchkiss Sara
Published: June 2006

We used charcoal and fossil pollen to investigate how fire, vegetation and climate have interacted over the past 2300 years at Ferry Lake, located on a sand plain in northwestern Wisconsin. Pollen analysis shows a rapid transition from oak (Quercus spp.)-dominated woodland to a relatively open pine (Pinus spp.) forest at 1450 cal. yr BP, and a more closed-canopy pine forest beginning about 700 cal. yr BP. We calculated accumulation rates of 125-250 ųm charcoal fragments (CHAR) in contiguous 0.5 cm thick sediment samples, each representing 7-10 years. Graminoid charcoal fragments were tallied separately to track the relative abundance of grass charcoal. During the oak period charcoal peaks have relatively weak periodicity and relatively high accumulation rates of grass charcoal. Charcoal peaks are less frequent (with a periodicity of 130-200 years), and larger during the open-canopy pine period, with lower grass CHAR. CHAR of both charcoal types decreases further between 1000 and 850 cal. yr BP and remains low until the period of European settlement. Several hundred years later (700 cal. yr BP) white pine pollen increases and pollen from herbaceous taxa decreases, suggesting a more mesic, closed-canopy forest. Our results demonstrate that the vegetation and fire regime at this sandplain site changed substantially, but apparently not synchronously, during the last 2300 years, a period when millennial-scale regional climate was relatively similar to modern.
A postglacial palaeoecological record from the San Juan Mountains of Colorado USA: fire, climate and vegetation history
Authors: Toney Jaime L. , Anderson R. Scott
Published: June 2006

Continuous sediment, charcoal and pollen records were developed from a- 4.5 m sediment core from Little Molas Lake (LML), 3370 m elevation, San Juan County, CO. LML formed by 11 200 cal. BP subsequent to glacial retreat. Turbated clay and gyttja was derived from in-lake productivity and outwash sediments from the drainage basin from 1 1 200 cal. BP until-10 200 cal. BP. Cessation of glacial input and replacement of tundra with Picea forest correlates with the termination of the Younger Dryas and indicates warming. An increase in diploxylon pollen (cf. P ponderosa), probably from lower elevations, reflects the influence of the southwestern monsoon c. 10 160 cal. BP. Pollen ratios indicate that Picea and other conifers persisted near the lake for the remainer of the Holocene. The driest Holocene period occurs c. 6200 to 5900 cal. BP, when lake levels were the lowest as indicated by all the proxy records. Wetter conditions during the last c. 2600 cal. BP favoured the expansion of P edulis and P ponderosa. Lateglacial fire events occurred on average every 65 years with a doubling of the fire return interval in the early Holocene. The former may reflect an increase in biomass for burning during a period of rapid vegetation turnover. The lowest fire event frequency occurs during the Neoglacial (after c. 4100), during a period of moister and cooler climate. The most recent pronounced peak in charcoal coincides with the historically documented AD 1879 Lime Creek Burn.
Late-Holocene environmental history of two New England ponds: natural dynamics versus human impacts
Authors: Kdster Dorte , Pienitz Reinhard
Published: June 2006

Analyses of sedimentary diatoms in two New England ponds reveal limnological changes during the past 2500 years that are related to climatic change, anthropogenic activities and natural disturbance. Deforestation in the lake catchments during the eighteenth and nineteenth centuries temporarily affected diatom assemblages, with subsequent recovery. However, algal communities did not return completely to presettlement conditions as a result of long-term trends in climatic change, small-scale natural disturbances and delayed watershed recovery from acidification. A short-term rise in diatominferred dissolved organic carbon (DOC) in Levi Pond was related to partial removal of vegetation by logging in the catchment, and a similar DOC increase at North Round Pond is correlated with a hurricane and increased aquatic productivity. At Levi Pond, increasing diatom-inferred DOC concentrations during the past c. 2000 years likely reflect a long-term increase in allochthonous organic matter and peat development in the watershed related to moister conditions, supported by corresponding patterns in the stable-isotope, chironomid and pollen records. These results correspond with moisture patterns in adjacent areas inferred from pollen and sediment analyses, suggesting that diatoms in Levi Pond recorded a larger regional trend in increasing moisture. This is the first study in a temperate region that links diatom-inferred DOC concentration to past changes in moisture balance, suggesting that fossil diatoms may be a promising proxy for future palaeohydrological studies in temperate regions. However, more studies are necessary to separate the effects of peatland growth and allochthonous organic-matter input on lake-DOC concentrations.
Coastal dune ridge systems as chronological markers of palaeoseismic activity: a 650-yr record from southwest New Zealand
Authors: Wells Andrew , Goff James
Published: June 2006

A study of two shore-parallel dune ridge sequences in southwest New Zealand shows that tectonic activity has been the primary controlling influence in their formation since at least AD 1450. The timing of dune-building episodes at the mouths of the Haast and Okuru Rivers was determined using the ages of colonizing trees. Episodic dune formation was indicated by clear discontinuities in tree ages, with distinct cohorts having colonized successive, newly formed, dune ridge-swale units. At both sites, four dune ridge-swale units have formed since AD 1450, with each unit closely postdating an Alpine fault rupture (c. AD 1460, c. AD 1615, AD 1717, AD 1826). Colonizing cohorts of trees started growing within 20-46 years after an earthquake at both sites, and all known major regional earthquakes have resulted in a dunebuilding episode. No other dunes are present at either site. Progradational coastal dune systems have potential as a tool for palaeoseismic studies. In regions with high background levels of sediment delivery to limit erosion/burial of dunes and with little coseismic subsidence, dune systems may preserve a spatially discrete record of major earthquake-induced sedimentation events over the Holocene. Earthquakes are a key driver of palaeoenvironmental change and coastal plain development in this tectonically active region.
Holocene climate changes in the monsoon/arid transition reflected by carbon concentration in Daihai Lake of Inner Mongolia
Authors: Xiao Jule , Wu Jintao , Si Bin , Liang Wendong , Nakamura Toshio , Liu Baolin , Inouchi Yoshio
Published: June 2006

Two sediment cores recovered in the central part of Daihai Lake in north-central China were analysed at 2-to 4-cm intervals for total inorganic and organic carbon (TIC and TOC) concentrations. The TIC concentration is inferred to reflect temperatures over the lake region and an increase in the TIC concentration implies an increase in the temperature. TOC concentration is considered to reflect the precipitation in the lake basin and higher TOC concentrations denote more precipitations. Thus AMS 14C time series of the TIC and TOC records of Daihai Lake sediments uncovers a detailed history of changes in temperature and precipitation in north-central China during the last c. 12 000 yr. The Holocene, an epoch of postglacial warmth, started c. 11 500 cal. yr BP, and can be subdivided into three stages: the early (c. 11 500-8100 cal. yr BP), middle (c. 8100-3300 cal. yr BP) and the late Holocene (c. 3300-0 cal. yr BP). The climate was warm and dry during the early Holocene, warm and wet during the middle Holocene, and in the late Holocene became cooler and drier but displayed a relatively warmer and wetter interval between c. 1700 and 1300 cal. yr BP. The Holocene Climatic Optimum, defined as a postglacial episode of both megathermal and megahumid climate, might have occurred in north-central China between c. 8100 and 3300 cal. yr BP, and the climate during this period was variable and punctuated by cool and/or dry events. We infer that changes in the temperature were directly controlled by changes in summer solar radiation in the Northern Hemisphere resulting from progressive changes in the Earth's orbital parameters. Whereas an increase in the monsoonal precipitation could be closely related to an increase in the sea surface temperature of the low-latitude Pacific Ocean, an increase in the temperature and size of the Western Pacific Warm Pool and a westward shifted and strengthened Kuroshio Current in the western Pacific.
The oxbow sedimentary subenvironment: its value in palaeogeographical studies as illustrated by selected fluvial systems in the Upper Odra catchment, southern Poland
Authors: Wojcicki Krzysztof J.
Published: June 2006

Research was conducted in valleys of sinuous rivers that drain medium-high mountain, foreland basin and upland areas, where loose Quaternary deposits predominate. The cyclic pattern determined for deposits of the oxbow sedimentary subenvironment in the Upper Odra Basin can be expressed as a few alternative sequences. The best-developed cycle occurring on a relatively high level of probability, is represented by the unilateral transition from channel to overbank deposits and upwards-bilateral oscillations between overbank and biochemical, as well as biochemical and slope deposits. In the first stage, oxbow filling processes are usually determined by autocyclic factors (resulting from spatial relations between abandoned channels and the active channel). As a consequence, overbank and/or biochemical sediments usually overlie channel deposits. Later, allocyclic processes could easily dominate autocyclic processes. In these cases, overbank, slope and late-Holocene alluvial fan deposits were delivered to oxbow basins as a result of the influence of outside factors such as climate or human impact. In the Upper Odra catchment, facies succession in the sequences of deposits infilling abandoned channels was mainly determined by climatic factors (in the Late Vistulian, early and mid-Holocene) and anthropogenic factors (in the late Holocene, especially in the last dozen centuries or more). The course of sedimentary processes conditioned by climate and human activity was modified by orographic factors associated with spatial relations among abandoned channels and both the active channel as well as valley slopes. However, the geological structure had a smaller influence on the course of sedimentary processes in the oxbows. The diversity of bedrock lithology in the individual drainage areas determined the thickness and lithological features of the given series of deposits but not the facies succession.
Radiocarbon dating of mid-Holocene megaflood deposits in the Jokulsa a Fjollum, north Iceland
Authors: Kirkbride Martin P. , Dugmore Andrew J. , Brazier Vanessa
Published: June 2006

Two megafloods in the canyon of the Jokulsi i Fjóllum, the major northern routeway for glaciovolcanic floods from Vatnajókull, have been closely dated by 14C AMS dates from Betula macrofossils within peat immediately below beds of flood-deposited sand. Ages of c. 4415 and c. 4065 yr BP (5020 and 4610 cal. yr BP) are consistent with the presence of the Hekla 4 tephra (c. 3830 yr BP) resting on the upper surface of the younger flood sand. These sediments are correlated across the Jókulsa a Fjollum canyon with the upper flood sands in a stack recording around 16 flood events. Deposits on both sides of the canyon were trimmed by the last megaflood after the Hekla 3 tephra fall at c. 2900 yr BP, and the highest Holocene flood stages were at the culmination of a series peaking at c. 3500 yr BP. These floods have wider palaeoclimatic significance because they require the formation of large subglacial reservoirs below Vatnajókull. Therefore, the dated floods indicate that a large composite ice cap covered volcanoes in the southeastern highlands through the early and middle Holocene, and that flood routeways largely switched to the south after c. 3500 yr BP.
A glacial lake outburst flood associated with recent mountain glacier retreat, Patagonian Andes
Authors: Harrison Stephan , Glasser Neil , Winchester Vanessa , Haresign Eleanor , Warren Charles , Jansson Krister
Published: June 2006

Geomorphological mapping, sedimentology, lichenometry and dendrochronology were used to assess the nature and timing of glacier recession, moraine development and catastrophic mass movements in a tributary of the Leones valley, east of the Hielo Patagónico Norte, Chile. We show that during the 'Little Ice Age' Glaciar Calafate advanced downvalley to produce a terminal moraine. Recession of the glacier from this position occurred in the 1 870s and produced a moraine dammed lake. In late 2000 a large rockfall into the lake breached the moraine and triggered a glacial lake outburst flood (GLOF) that entrained and subsequently deposited some 2 x 106 m3 of material. We interpret this event as a delayed paraglacial response to the retreat of Glaciar Calafate during the twentieth century.
Phthalate affect the reproductive function and sexual behavior of male Wistar rats
Authors: Dalsenter P R , Santana G M , Grande S W , Andrade A Jm , Araújo S L
Published: June 2006

Phthalates are chemicals used in many industrial products (plastic toys, shampoos, soaps), and are suspected of inducing adverse effects on the male reproductive system. In the present study, we evaluated the effects of the plasticizer di-(2-ethylhexyl)-phthalate (DEHP) on the reproductive function and sexual behavior of male offspring rats, exposed in utero and during lactation (0, 20, 100 and 500 mg/kg per day by gavage). The effects produced clearly demonstrate the ability of DEHP to disrupt the androgen-regulated development of the male reproductive tract. Absolute and relative weights of androgen-dependent tissue organs (ventral prostate and seminal vesicle) were significantly reduced at the highest dose level tested (500 mg/kg per day). Impairment of male sexual behavior (500 mg/kg per day) was also observed. Moreover, the reduction in daily sperm production and epididymal sperm counts observed after administration of the highest dose suggests an impairment of the spermatogenic processes. Most of the adverse effects reported here were observed both during puberty and during adulthood, indicating permanent effects of in utero and lactational DEHP exposure.
Effect of chromium on vertebrae, femur and calvaria of adult male rats
Authors: Sankaramanivel S , Jeyapriya R , Hemalatha D , Djody S , Arunakaran J , Srinivasan N
Published: June 2006

Alloys of chromium have a long history of success in the surgical treatment of many orthopaedic defects. Nonetheless, prostheses loosening are commonly found around arthoplasties due to corrosion of metals. On this basis, it is hypothesized that chromium accumulation interferes with remodeling of bone. The present study aims to analyse the toxic effects of chromium on bone phosphatases in various regions of the bone in rats. Rats were treated with chromium intraperitoneally (0.5 mg/kg) in the form of potassium dichromate for 5 days. The accumulation of chromium is approximately 5.2-fold in the vertebrae, 8.9-fold in the femur and 8.7-fold in the calvaria, when compared to control. Chromium administration significantly reduced the activity of enzymes, eg, alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). The study revealed a significant increase in the concentration of calcium, altered bone formation rate and bone morphology in the femur, vertebrae and calvaria. The interesting findings of the current study suggest altered bone turnover.
Cardiac lesions induced by 5-fluorouracil in the rabbit
Authors: Tsibiribi P , Bui-Xuan C , Bui-Xuan B , Lombard-Bohas C , Duperret S , Belkhiria M , Tabib A , Maujean G , Descotes J , Timour Q
Published: June 2006

Cardiotoxicity is a rare, but well-recognized complication of treatments with the anti-cancer drug 5-fluorouracil (5FU). The underlying mechanism, however, is not fully elucidated. A spasm of the coronary arteries is often considered to be the leading cause of myocardial ischemia and decreased contractility associated with 5FU. As spasm cannot account for all reported adverse cardiac effects, the present study was undertaken to search for alternative mechanisms. Groups of six rabbits were given either a single intravenous dose of 50 mg/kg 5FU or four intravenous doses of 15 mg/kg 5FU at 7-day intervals. A third group served as control. The heart was removed shortly after death or scheduled sacrifice of the animals, to perform macroscopic and microscopic examinations of the heart and to evidence apoptosis by the TUNEL method. Following a single dose of 50 mg/kg 5FU, all animals rapidly developed a massive hemorrhagic myocardial infarct with spasms of the proximal coronary arteries. Repeated infusions of 15 mg/kg 5FU induced left ventricular hypertrophy, foci of myocardial necrosis, thickening of intra-myocardial arterioles, and disseminated apoptosis in myocardial cells of the epicardium, as well as endothelial cells of the distal coronary arteries. These results indicate that a spasm of the coronary arteries is not the only mechanism of 5FU cardiotoxicity, and that apoptosis of myocardial and endothelial cells can result in inflammatory lesions mimicking toxic myocarditis.
Effects of adenylyl cyclase and protein kinase A inhibition on signaling enzymes in natural killer cells: comparison to tributyltin
Authors: Whalen M M , Odman-Ghazi S O
Published: June 2006

Natural killer (NK) cells are lymphocytes capable of destroying tumor cells and virally-infected cells without prior sensitization. In a previous study, we found that inhibition of adenylyl cyclase (AC) or cAMP-dependent protein kinase (PKA) decreased the ability of NK cells to destroy tumor cells. We also found that the environmental contaminant tributyltin (TBT), at concentrations of 300 500 nM, decreased tumor-cell lysis by NK cells, as well as their intracellular levels of cAMP. This suggested that the decreases in cAMP associated with TBT (300 500 nM) may, in part, be responsible for loss of cytotoxic function. Here, we investigated the effects of inhibition of AC or PKA on enzymes that are required in the NK tumorolytic process and compared them to those of TBT exposure. The enzymes studied were: the protein tyrosine kinase (PTK), syk; phospholipase C gamma1 (PLCg1); and the mitogen activated protein kinase (MAPK), p44/42. Exposure of NK cells to the AC inhibitor 2?,5?-dideoxyadenosine (DDA) significantly increased the total level of PLCg1 by 67% after 60 min and the level of p44/42 by about 30%. Exposure to the PKA inhibitor H-89 significantly increased the levels of the phosphorylated (activated) p44/42 (90%) after 60 min. Exposure to TBT increased the levels of PLCg1 by about 50%. Previously, we found that exposure to TBT increased the phosphorylation of p44/42 within 5 min. These results indicate that AC inhibition caused alterations of the levels of key enzymes, while decreased PKA activity caused an increase in p44/42 activation. They also suggest that the effects of decreased levels of cAMP on these key cytotoxic signaling proteins may overlap, to a very limited extent, with those of TBT.
Anti-clastogenic effect of b-glucan extracted from barley towards chemically induced DNA damage in rodent cells
Authors: Angeli J Pf , Ribeiro L R , Bellini M F , Mantovani M S
Published: June 2006

b-Glucan (BG) was tested in vitro to determine its potential clastogenic and/or anti-clastogenic activity, and attempts were made to elucidate its possible mechanism of action by using combinations with an inhibitor of DNA polymerase. The study was carried out on cells deficient (CHO-k1) and cells proficient (HTC) in phases I and II enzymes, and the DNA damage was assessed by the chromosomal aberration assay. BG did not show a clastogenic effect, but was anti-clastogenic in both cell lines used, and at all concentrations tested (2.5, 5 and 10 mg/mL) in combination with damage inducing agents (methylmethane sulfonate in cell line CHO-k1, and methylmethane sulfonate or 2-aminoanthracene in cell line HTC). BG also showed a protective effect in the presence of a DNA polymerase b inhibitor (cytosine arabinoside-3-phosphate, Ara-C), demonstrating that BG does not act through an anti-mutagenic mechanism of action involving DNA polymerase b.
Protective effects of fruit extracts of Hippophae rhamnoides L. against arsenic toxicity in Swiss albino mice
Authors: Gupta R , Flora S JS
Published: June 2006

Seabuckthorn (Hippophae rhamnoides L.) berry has a long history of applications as a food and medicinal ingredient in eastern countries. The present study was carried out to investigate the effect of different fruit extracts of H. rhamnoides on altered biochemical parameters indicative of haematological alterations, tissue oxidative stress, and arsenic concentration in arsenicexposed mice (2.5 mg/kg body weight, intraperitoneally). Two aqueous extracts (at room temperature and under reflux condition) and an ethanolic extract of H. rhamnoides at a dose of 500 mg/kg body weight were coadministered daily during arsenic exposure in mice for 3 weeks. Exposure to arsenic led to a significant inhibition of blood @aminolevulinic acid dehydratase (ALAD) activity, suggesting disturbed haem synthesis pathway. Arsenic also caused significant depletion of reduced hepatic glutathione (GSH) level, glutathione S-transferase (GST) and glutathione peroxidase and catalase activities, while it increased the level of thiobarbituric acid reactive substance (TBARS), suggesting liver oxidative stress. Most of the altered biochemical variables responded favorably to the co-supplementation of H. rhamnoides, particularly the aqueous fruit extract, extracted at room temperature (HF-WRT). However, arsenic concentration in blood and tissues remained unchanged, suggesting the lack of chelating property of fruit extract of H. rhamnoides. The present study, thus, led us to conclude that the fruit extract of H. rhamnoides has a significant protective role against arsenic-induced oxidative injury. However, it lacks the ability to remove arsenic from the binding sites, suggesting that the herbal extract could be co-administered with a chelating agent of known efficacy during treatment of arsenic to achieve the optimum effect of chelation treatment.