224 research outputs found

    How does the global Moderate Resolution Imaging Spectroradiometer (MODIS) Fraction of Photosynthetically Active Radiation (FPAR) product relate to regionally developed land cover and vegetation products in a semi-arid Australian savanna?

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    Spatio-temporally variable information on total vegetation cover is highly relevant to water quality and land management in river catchments adjacent to the Great Barrier Reef, Australia. A time series of the global Moderate Resolution Imaging Spectroradiometer (MODIS) Fraction of Photosynthetically Active Radiation (FPAR; 2000-2006) and its underlying biome classification (MOD12Q1) were compared to national land cover and regional, remotely sensed products in the dry-tropical Burdekin River. The MOD12Q1 showed reasonable agreement with a classification of major vegetation groups for 94% of the study area. We then compared dry-seasonal, quality controlled MODIS FPAR observations to (i) Landsat-based woody foliage projective cover (wFPC) (2004) and (ii) MODIS bare ground index (BGI) observations (2001-2003). Statistical analysis of the MODIS FPAR revealed a significant sensitivity to Landsat wFPC-based Vegetation Structural Categories (VSC) and VSC-specific temporal variability over the 2004 dry season. The MODIS FPAR relation to 20 coinciding MODIS BGI dry-seasonal observations was significant (ρ < 0.001) for homogeneous areas of low wFPC. Our results show that the global MODIS FPAR can be used to identify VSC, represent VSC-specific variability of PAR absorption, and indicate that the amount, structure, and optical properties of green and non-green vegetation components contribute to the MODIS FPAR signal

    Blood-based oxidative stress markers and cognitive performance in early old age : the HAPIEE study

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    BACKGROUND/AIMS: Oxidative stress is involved in Alzheimer disease pathology, but its impact on cognitive function in community-dwelling older adults remains unknown. We estimated associations between serum oxidative stress markers and cognitive function in early old age. METHODS: Subjects aged 45-69 years recruited in urban centers in Central and Eastern Europe had memory, verbal fluency, and processing speed assessed at baseline (2002-2005) and 3 years later. Derivatives of reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), and total thiol levels (TTLs) were measured at baseline in a subsample. Linear regression was used to estimate associations of biomarkers with cognitive test scores cross-sectionally (n = 4,304) and prospectively (n = 2,882). RESULTS: Increased d-ROM levels were inversely associated with global cognition and verbal fluency cross-sectionally and in prospective analysis; observed effects corresponded to 3-4 years' higher age. TTL was inconsistently associated with memory. BAP was not related to cognitive function. CONCLUSION: This study found modest evidence for a relationship between serum d-ROMs and cognitive function in a population sample of older adults

    Structural properties and Raman modes of zinc blende InN epitaxial layers

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    We report on x-ray diffraction and micro-Raman scattering studies on zinc blende InN epitaxial films. The samples were grown by molecular beam epitaxy on GaAs(001) substrates using a InAs layer as a buffer. The transverse-optical (TO) and longitudinal-optical phonon frequencies at Gamma of c-InN are determined and compared to the corresponding values for c-GaN. Ab initio self-consistent calculations are carried out for the c-InN c-GaN lattice parameters and TO phonon frequencies. A good agreement between theory and experiment is found. (C) 1999 American Institute of Physics. [S0005-6951(99)00503-3].74336236

    Association of glycated hemoglobin A1c levels with cardiovascular outcomes in the general population: results from the BiomarCaRE (Biomarker for Cardiovascular Risk Assessment in Europe) consortium

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    Background: Biomarkers may contribute to improved cardiovascular risk estimation. Glycated hemoglobin A1c (HbA1c) is used to monitor the quality of diabetes treatment. Its strength of association with cardiovascular outcomes in the general population remains uncertain. This study aims to assess the association of HbA1c with cardiovascular outcomes in the general population. Methods: Data from six prospective population-based cohort studies across Europe comprising 36,180 participants were analyzed. HbA1c was evaluated in conjunction with classical cardiovascular risk factors (CVRFs) for association with cardiovascular mortality, cardiovascular disease (CVD) incidence, and overall mortality in subjects without diabetes (N = 32,496) and with diabetes (N = 3684). Results: Kaplan\u2013Meier curves showed higher event rates with increasing HbA1c levels (log-rank-test: p &lt; 0.001). Cox regression analysis revealed significant associations between HbA1c (in mmol/mol) in the total study population and the examined outcomes. Thus, a hazard ratio (HR) of 1.16 (95% confidence interval (CI) 1.02\u20131.31, p = 0.02) for cardiovascular mortality, 1.13 (95% CI 1.03\u20131.24, p = 0.01) for CVD incidence, and 1.09 (95% CI 1.02\u20131.17, p = 0.01) for overall mortality was observed per 10&nbsp;mmol/mol increase in HbA1c. The association with CVD incidence and overall mortality was also observed in study participants without diabetes with increased HbA1c levels (HR 1.12; 95% CI 1.01\u20131.25, p = 0.04) and HR 1.10; 95% CI 1.01\u20131.20, p = 0.02) respectively. HbA1c cut-off values of 39.9&nbsp;mmol/mol (5.8%), 36.6&nbsp;mmol/mol (5.5%), and 38.8&nbsp;mmol/mol (5.7%) for cardiovascular mortality, CVD incidence, and overall mortality, showed also an increased risk. Conclusions: HbA1c is independently associated with cardiovascular mortality, overall mortality and cardiovascular disease in the general European population. A mostly monotonically increasing relationship was observed between HbA1c levels and outcomes. Elevated HbA1c levels were associated with cardiovascular disease incidence and overall mortality in participants without diabetes underlining the importance of HbA1c levels in the overall population

    Hypercalcemia and huge splenomegaly presenting in an elderly patient with B-cell non-Hodgkin's lymphoma: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Hypercalcemia is the major electrolyte abnormality in patients with malignant tumors. It can be due to localized osteolytic hypercalcemia or elaboration of humoral substances such as parathyroid hormone-related protein from tumoral cells. In hematological malignancies, a third mechanism of uncontrolled synthesis and secretion of 1-25(OH)<sub>2</sub>D<sub>3 </sub>from tumoral cells or neighboring macrophages may contribute to the problem. However, hypercalcemia is quite unusual in patients with B-cell non-Hodgkin's lymphoma.</p> <p>Case presentation</p> <p>An 85-year-old Caucasian woman presented with low grade fever, anorexia, abdominal discomfort and fullness in her left abdomen for the last six months. She was mildly anemic and complained of fatigability. She had huge splenomegaly and was hypercalcemic. After correction of her hypercalcemia, she had a splenectomy. Microscopic evaluation revealed a malignant lymphoma. Her immunohistochemistry was positive for leukocyte common antigen, CD20 and parathyroid hormone-related peptide.</p> <p>Conclusion</p> <p>Immunopositivity for parathyroid hormone-related peptide clearly demonstrates that hypersecretion of a parathyroid hormone-like substance from the tumor had led to hypercalcemia in this case. High serum calcium is seen in only seven to eight percent of patients with B-cell non-Hodgkin's lymphoma, apparently due to different mechanisms. Evaluation of serum parathyroid hormone-related protein and 1-25(OH)<sub>2</sub>D<sub>3 </sub>can be helpful in diagnosis and management. It should be noted that presentation with hypercalcemia has a serious impact on prognosis and survival.</p

    1,25-dihydroxyvitamin D3 restrains CD4+ T cell priming ability of CD11c+ dendritic cells by upregulating expression of CD31

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    Dendritic cells (DC) are specialized sentinel cells that bridge the innate and adaptive immune response and play a crucial role in shaping the adaptive immune response. Vitamin D, a known epidemiological risk factor for the development of several autoimmune diseases, influences the development of dendritic cells. Consequently, vitamin D metabolites are frequently used in protocols to develop therapeutic dendritic cell therapies for autoimmune diseases. However, the mechanisms by which vitamin D modulates DC function remain poorly understood. We investigated the effects of vitamin D on murine CD11c+ bone marrow derived DC (BMDC) function by analyzing global gene expression in CD11c+ BMDC generated in the presence (VitD-CD11c+BMDC) or absence (Veh-CD11c+BMDC) of the active vitamin D metabolite, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Seven genes were significantly increased in expression in both immature and LPS-matured VitD-CD11c+BMDC, one of which was CD31, a member of the immunoglobulin superfamily. Gene knockdown of CD31 enhanced the ability of VitD-CD11c+BMDC to prime naïve CD4+ T cells in vitro; conversely, increased expression of CD31 on vehicle treated CD11c+BMDC restrained their T cell priming abilities. Time-lapse imaging of BMDC and CD4+ T cells during in vitro priming revealed that CD31 reduced the BMDC–T cell interaction time. Finally, we confirmed a similar effect of 1,25(OH)2D3 on human CD34+ cell-derived CD11c+DC, whereby DC generated in the presence of 1,25(OH)2D3 had increased CD31 expression. In summary, we show that both mouse and human DC generated in the presence of 1,25(OH)2D3 upregulate CD31 expression, resulting in a reduced ability to prime CD4+ T cells by impairing a stable cell-cell contact

    World Health Organization cardiovascular disease risk charts: revised models to estimate risk in 21 global regions

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    BACKGROUND: To help adapt cardiovascular disease risk prediction approaches to low-income and middle-income countries, WHO has convened an effort to develop, evaluate, and illustrate revised risk models. Here, we report the derivation, validation, and illustration of the revised WHO cardiovascular disease risk prediction charts that have been adapted to the circumstances of 21 global regions. METHODS: In this model revision initiative, we derived 10-year risk prediction models for fatal and non-fatal cardiovascular disease (ie, myocardial infarction and stroke) using individual participant data from the Emerging Risk Factors Collaboration. Models included information on age, smoking status, systolic blood pressure, history of diabetes, and total cholesterol. For derivation, we included participants aged 40-80 years without a known baseline history of cardiovascular disease, who were followed up until the first myocardial infarction, fatal coronary heart disease, or stroke event. We recalibrated models using age-specific and sex-specific incidences and risk factor values available from 21 global regions. For external validation, we analysed individual participant data from studies distinct from those used in model derivation. We illustrated models by analysing data on a further 123 743 individuals from surveys in 79 countries collected with the WHO STEPwise Approach to Surveillance. FINDINGS: Our risk model derivation involved 376 177 individuals from 85 cohorts, and 19 333 incident cardiovascular events recorded during 10 years of follow-up. The derived risk prediction models discriminated well in external validation cohorts (19 cohorts, 1 096 061 individuals, 25 950 cardiovascular disease events), with Harrell's C indices ranging from 0·685 (95% CI 0·629-0·741) to 0·833 (0·783-0·882). For a given risk factor profile, we found substantial variation across global regions in the estimated 10-year predicted risk. For example, estimated cardiovascular disease risk for a 60-year-old male smoker without diabetes and with systolic blood pressure of 140 mm Hg and total cholesterol of 5 mmol/L ranged from 11% in Andean Latin America to 30% in central Asia. When applied to data from 79 countries (mostly low-income and middle-income countries), the proportion of individuals aged 40-64 years estimated to be at greater than 20% risk ranged from less than 1% in Uganda to more than 16% in Egypt. INTERPRETATION: We have derived, calibrated, and validated new WHO risk prediction models to estimate cardiovascular disease risk in 21 Global Burden of Disease regions. The widespread use of these models could enhance the accuracy, practicability, and sustainability of efforts to reduce the burden of cardiovascular disease worldwide. FUNDING: World Health Organization, British Heart Foundation (BHF), BHF Cambridge Centre for Research Excellence, UK Medical Research Council, and National Institute for Health Research
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