The soils of the Pampas are thought to be generally non-contaminated but there is growing evidence of trace element accumulation at some specific sites. The goal of this study was to measure the current levels of the main Potentially Toxic Elements (PTE) in the top horizon and in specific soil profiles so that we would establish the baseline concentrations of these elements. Eighty-eight top soils and three soil profiles were sampled. The samples were acid digested. Arsenic, boron, barium, cadmium, cobalt, chromium, copper, lead, manganese, mercury, molybdenum, nickel, silver, selenium and zinc were determined with inductively coupled argon plasma emission spectrometry (ICPES).
All of the values found are within the normal range for uncontaminated soils as reported from several continents. Elements with high environmental risk potential are lower than the admissible range of the European Union and some of them are orders of magnitude lower than those of the United States Environmental Protection Agency (US-EPA) 501 levels. Potentially Toxic Elements contents increased with depth or showed a maximum concentration at the B2 horizon. This is related to the parent material and the pedogenetic processes but not to recent contamination. Soil profiles showed higher concentrations of PTE in clayey horizons. However, these relationships did not appear in top soil samples in any soil Great Group studied. The shown data establishes a baseline for PTE concentrations for Pampas soils. 相似文献
The transporter associated with antigen processing (TAP) is an ATP binding cassette transporter responsible for peptide translocation into the lumen of the endoplasmic reticulum for assembly with major histocompatibility complex class I molecules. Immunoaffinity-purified TAP particles comprising TAP1 and TAP2 polypeptides, and TAP2 particles alone were characterized after detergent solubilization and studied by electron microscopy. Projection structures of TAP1+2 particles reveal a molecule approximately 10 nm across with a deeply staining central region, whereas TAP2 molecules are smaller in projection. A three-dimensional structure of TAP reveals it is isolated as a single heterodimeric complex, with the TAP1 and TAP2 subunits combining to create a central 3-nm-diameter pocket on the predicted endoplasmic reticulum-lumenal side. Its structural similarity to other ABC transporters demonstrates a common tertiary structure for this diverse family of membrane proteins. 相似文献
The development of vascular disease is accelerated in hyperglycemic states. Vascular injury plays a pivotal role in the progression of atherosclerotic vascular disease in diabetes, which is characterized by increased vascular smooth muscle cell (VSMC) proliferation and extracellular matrix accumulation. We previously reported that diabetes alters the activity of the kallikrein-kinin system and results in the upregulation of kinin receptors in the vessel wall. To determine whether glucose can directly influence the regulation of kinin receptors, the independent effect of high glucose (25 mM) on B(2)-kinin receptors (B2KR) in VSMC was examined. A threefold increase in B2KR protein levels and a 40% increase in B2KR surface receptors were observed after treatment with high glucose after 24 h. The mRNA levels of B2KR were also significantly increased by high glucose as early as 4 h later. To elucidate the cellular mechanisms by which glucose regulates B2KR, we examined the role of protein kinase C (PKC). High glucose increased total PKC activity and resulted in the translocation of conventional PKC isoforms (beta(1) and beta(2)), novel (epsilon), and atypical (zeta) PKC isoforms into the membrane. Inhibition of PKC activity prevented the increase in B2KR levels induced by ambient high glucose. These findings provide the first evidence that glucose regulates the expression of B(2) receptors in VSMC and provide a rationale to further study the interaction between glucose and kinins on the pathogenesis of atherosclerotic vascular disease in diabetes. 相似文献
Nearest-neighbour analysis is commonly used to calculate indices of aggregation in groups of animals. It has several problems, however, including lack of data independence and, when studying groups of animals penned at high densities, the difficulty of determining a given individual's nearest neighbour. We describe an entropy-based method to assess the degree of association (or segregation) of groups of animals. We show that this method gives more information and is more sensitive than the nearest-neighbour technique. An example with a particular experimental situation (mixing groups of lambs) is presented. Copyright 2000 The Association for the Study of Animal Behaviour. 相似文献
Accumulation of extracellular matrix (ECM) is a hallmark feature of vascular disease. We have previously shown that hyperglycemia induces the expression of B(2)-kinin receptors in vascular smooth muscle cells (VSMC) and that bradykinin (BK) and hyperglycemia synergize to stimulate ECM production. The present study examined the cellular mechanisms through which BK contributes to VSMC fibrosis. VSMC treated with BK (10(-8) M) for 24 h significantly increased alpha(2)(I) collagen mRNA levels. In addition, BK produced a two- to threefold increase in alpha(2)(I) collagen promoter activity in VSMC transfected with a plasmid containing the alpha(2)(I) collagen promoter. Furthermore, treatment of VSMC with BK for 24 h produced a two- to threefold increase in the secretion rate of tissue inhibitor of metalloproteinase 1 (TIMP-1). The increase in alpha(2)(I) collagen mRNA levels and alpha(2)(I) collagen promoter activity, as well as TIMP-1 secretion, in response to BK were blocked by anti-transforming growth factor-beta (anti-TGF-beta) neutralizing antibodies. BK (10(-8) M) increased the endogenous production of TGF-beta1 mRNA and protein levels. Inhibition of the mitogen-activated protein kinase (MAPK) pathway by PD-98059 inhibited the increase of alpha(2)(I) collagen promoter activity, TIMP-1 production, and TGF-beta1 protein levels observed in response to BK. These findings provide the first evidence that BK induces collagen type I and TIMP-1 production via autocrine activation of TGF-beta1 and implicate MAPK pathway as a key player in VSMC fibrosis in response of BK. 相似文献
Cellular senescence is a process that results from a variety of stresses, leading to a state of irreversible growth arrest. Senescent cells accumulate during aging and have been implicated in promoting a variety of age‐related diseases. Mitochondrial stress is an effective inducer of cellular senescence, but the mechanisms by which mitochondria regulate permanent cell growth arrest are largely unexplored. Here, we review some of the mitochondrial signaling pathways that participate in establishing cellular senescence. We discuss the role of mitochondrial reactive oxygen species (ROS), mitochondrial dynamics (fission and fusion), the electron transport chain (ETC), bioenergetic balance, redox state, metabolic signature, and calcium homeostasis in controlling cellular growth arrest. We emphasize that multiple mitochondrial signaling pathways, besides mitochondrial ROS, can induce cellular senescence. Together, these pathways provide a broader perspective for studying the contribution of mitochondrial stress to aging, linking mitochondrial dysfunction and aging through the process of cellular senescence. 相似文献
Dietary soy intake is associated with protection from breast cancer, but questions persist on the potential risks of the major soy isoflavone genistein (GEN) on female reproductive health. Here, we evaluated intermediate markers of cancer risk in uteri of cycling, young adult Sprague-Dawley rats lifetime exposed to one of three AIN-93G semipurified diets: casein (CAS), soy protein isolate (SPI+ with 276 mg GEN aglycone equivalents/kg) and CAS+GEN (GEN at 250 mg/kg). Postnatal day 50 (PND50) rats lifetime exposed to GEN or SPI+ had similar uterine luminal epithelium height, myometrial thickness, endometrial gland numbers, endometrial immunoreactive proliferating cell nuclear antigen (PCNA), and serum estrogen and progesterone, as CAS-fed rats. GEN-fed rats showed modestly increased apoptosis in uterine glandular epithelium, compared to those of CAS- or SPI+-fed groups. Diet had no effect on the uterine expression of genes for the tumor suppressors PTEN, p53 and p21, and the apoptotic-associated proteins Bcl2, Bax and progesterone receptor. Uterine tissue and serum concentrations of total GEN were higher in rats fed GEN than in those fed SPI+. Human Ishikawa endocarcinoma cells treated with GEN-fed rat serum tended to exhibit increased apoptotic status than those treated with CAS-fed rat serum. Exogenously added GEN (0.2 and 2 microM) increased, while estradiol-17beta (0.1 microM) decreased Ishikawa cell apoptosis, relative to untreated cells. Results suggest that lifetime dietary exposure to soy foods does not alter uterine cell phenotype in young adult rats, while GEN, by enhancing uterine endometrial glandular apoptosis in vivo and in vitro, may confer protection against uterine carcinoma. Given its limited influence on uterine phenotype of young adult females, GEN, when taken as part of soy foods or as supplement, should be favorably considered for other potential health benefits. 相似文献
We investigated two mortality events in wintering and migrating Song Thrushes (Turdus philomelos) in Catalonia, northeastern Spain in 2009 and 2010. Both episodes occurred in late February to mid-March during the spring migration. Salmonellosis produced by the serotype Salmonella enterica subsp. enterica serotype Hessarek (S. Hessarek) was identified as the cause of death in both episodes. Poor body condition, marked splenomegaly, and microscopic disseminated intravascular coagulation with numerous intravascular and tissular bacteria were the most consistent findings. Macro-restriction profiling by pulsed-field gel electrophoresis (PFGE) using XbaI was performed for epidemiologic typing of the S. Hessarek isolates. Two clusters were discernible, that are possibly related, with a similarity of 82.8%. Analysis comparing pectoral muscle and subcutaneous fat scores from the Song Thrushes that died from S. Hessarek with those from healthy Song Thrushes from nearby areas during 2009 and 2010 suggest that poor body condition was associated with the S. Hessarek infection. 相似文献