59 research outputs found
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A Holocene history of climate, fire, landscape evolution, and human activity in northeastern Iceland
Paleoclimate reconstructions across Iceland provide a template for past changes in climate across the northern North Atlantic, a crucial region due to its position relative to the global northward heat transport system and its vulnerability to climate change. The roles of orbitally driven summer cooling, volcanism, and human impact as triggers of local environmental changes in the Holocene of Iceland remain debated. While there are indications that human impact may have reduced environmental resilience during late Holocene summer cooling, it is still difficult to resolve to what extent human and natural factors affected Iceland's late Holocene landscape instability. Here, we present a continuous Holocene fire record of northeastern Iceland from proxies archived in Stóra Viðarvatn sediment. We use pyrogenic polycyclic aromatic hydrocarbons (pyroPAHs) to trace shifts in fire regimes, paired with continuous biomarker and bulk geochemical records of soil erosion, lake productivity, and human presence. The molecular composition of pyroPAHs and a wind pattern reconstruction indicate a naturally driven fire signal that is mostly regional. Generally low fire frequency during most of the Holocene significantly increased at 3 ka and again after 1.5 ka BP before known human settlement in Iceland. We propose that shifts in vegetation type caused by cooling summers over the past 3 kyr, in addition to changes in atmospheric circulation, such as shifts in North Atlantic Oscillation (NAO) regime, led to increased aridity and biomass flammability. Our results show no evidence of faecal biomarkers associated with human activity during or after human colonisation in the 9th century CE. Instead, faecal biomarkers follow the pattern described by erosional proxies, pointing toward a negligible human presence and/or a diluted signal in the lake's catchment. However, low post-colonisation levels of pyroPAHs, in contrast to an increasing flux of erosional bulk proxies, suggest that farming and animal husbandry may have suppressed fire frequency by reducing the spread and flammability of fire-prone vegetation (e.g. heathlands).
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Spatiotemporal variation of modern lake, stream, and soil water isotopes in Iceland
As global warming progresses, changes in high-latitude precipitation are expected to impart long-lasting impacts on Earth systems, including glacier mass balance and ecosystem structures. Reconstructing past changes in high-latitude precipitation and hydroclimate from networks of continuous lake records offers one way to improve forecasts of precipitation and precipitation–evaporation balances, but these reconstructions are currently hindered by the incomplete understanding of controls on lake and soil water isotopes. Here, we study the distribution of modern water isotopes in Icelandic lakes, streams, and surface soils collected in 2002, 2003, 2004, 2014, 2019, and 2020 to understand the geographic, geomorphic, and environmental controls on their regional and interannual variability. We find that lake water isotopes in open-basin (through-flowing) lakes reflect local precipitation, with biases toward the cold season, particularly in lakes with sub-annual residence times. Closed-basin lakes have water isotope and deuterium excess values consistent with evaporative enrichment. Interannual and seasonal variabilities of lake water isotopes at repeatedly sampled sites are consistent with instrumental records of winter snowfall; summer relative humidity; and atmospheric circulation patterns, such as the North Atlantic Oscillation. Summer surface soil water isotopes span the entire range of seasonal precipitation values in Iceland and appear to be consistently overprinted by evaporative enrichment, which can occur throughout the year, although the sampling depths were shallower than rooting depths for many plant types. This dataset provides new insight into the functionality of water isotopes in Icelandic environments and offers renewed possibilities for optimized site selection and proxy interpretation in future paleohydrological studies on this North Atlantic outpost.
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The role of human melanoma cell ICAM-1 expression on lymphokine activated killer cell-mediated lysis, and the effect of retinoic acid
Serum proteome analysis for profiling protein markers associated with carcinogenesis and lymph node metastasis in nasopharyngeal carcinoma
Nasopharyngeal carcinoma (NPC), one of the most common cancers in population with Chinese or Asian progeny, poses a serious health problem for southern China. It is unfortunate that most NPC victims have had lymph node metastasis (LNM) when first diagnosed. We believe that the 2D based serum proteome analysis can be useful in discovering new biomarkers that may aid in the diagnosis and therapy of NPC patients. To filter the tumor specific antigen markers of NPC, sera from 42 healthy volunteers, 27 non-LNM NPC patients and 37 LNM NPC patients were selected for screening study using 2D combined with MS. Pretreatment strategy, including sonication, albumin and immunoglobulin G (IgG) depletion, was adopted for screening differentially expressed proteins of low abundance in serum. By 2D image analysis and MALDI-TOF-MS identification, twenty-three protein spots were differentially expressed. Three of them were further validated in the sera using enzyme-linked immunosorbent assay (ELISA). Our research demonstrates that HSP70, sICAM-1 and SAA, confirmed with ELISA at sera and immunohistochemistry, are potential NPC metastasis-specific serum biomarkers which may be of great underlying significance in clinical detection and management of NPC
Circulating Intercellular Adhesion Molecule-1 and its Cellular Expression in Head and Neck Non-Hodgkin's Lymphomas, Including Lethal Midline Granuloma
Immunotherapy of Metastatic Malignant Melanoma by a Vaccine Consisting of Autologous Interleukin 2-Transfected Cancer Cells: Outcome of a Phase I Study
Expression of the tumor metastatic suppressor gene in mouse melanoma model: Inverse association to metastatic potential
Renal-Allograft Rejection - the Temporal Relationship and Predictive Value of Plasma Tnf(Alpha-And-Beta), Ifn-Gamma and Soluble Icam-1
WOS: A1995PU78700008PubMed ID: 7888051Recently, close interactions have been described between the tumour necrosis factors alpha and beta (TNF-alpha and beta), interferon-gamma (INF-gamma) and intercellular adhesion molecule-1 (ICAM-1) in T-cell mediated immune activation. During the process of renal graft rejection, the properties of these cytokines to act as powerful stimulators of macrophages, to upregulate class II MHC expression and to stabilise cell-to-cell binding make them of great potential interest. The aim of the present study was to determine the plasma levels of each cytokine and soluble ICAM-1 in 16 renal allograft recipients. We examined plasmas of patients for the first 2 weeks after transplantation and correlated results with the clinical pattern of rejection. Our data suggest an immunopathologic involvement of TNF-alpha, TNF-beta and slCAM-1 in renal allograft rejection and showed that there was a significant elevation in plasma concentrations of these parameters 2 or 3 days prior to the diagnosis of clinical rejection. Rises in INF-gamma did not appear to be significant with regard to rejection as very high levels were found in patients showing no evidence of clinical rejection
Renal allograft rejection: the temporal relationship and predictive value of plasma TNF (alpha and beta), IFN–gamma and soluble ICAM-1
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