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151.
Hansen PS Clarke RJ Buhagiar KA Hamilton E Garcia A White C Rasmussen HH 《American journal of physiology. Cell physiology》2007,292(3):C1070-C1077
The effect of diabetes on sarcolemmal Na+-K+ pump function is important for our understanding of heart disease associated with diabetes and design of its treatment. We induced diabetes characterized by hyperglycemia but no other major metabolic disturbances in rabbits. Ventricular myocytes isolated from diabetic rabbits and controls were voltage clamped and internally perfused with the whole cell patch-clamp technique. Electrogenic Na+-K+ pump current (Ip, arising from the 3:2 Na+-to-K+ exchange ratio) was identified as the shift in holding current induced by Na+-K+ pump blockade with 100 µmol/l ouabain in most experiments. There was no effect of diabetes on Ip recorded when myocytes were perfused with pipette solutions containing 80 mmol/l Na+ to nearly saturate intracellular Na+-K+ pump sites. However, diabetes was associated with a significant decrease in Ip measured when pipette solutions contained 10 mmol/l Na+. The decrease was independent of membrane voltage but dependent on the intracellular concentration of K+. There was no effect of diabetes on the sensitivity of Ip to extracellular K+. Pump inhibition was abolished by restoration of euglycemia or by in vivo angiotensin II receptor blockade with losartan. We conclude that diabetes induces sarcolemmal Na+-K+ pump inhibition that can be reversed with pharmacological intervention. sodium transport; insulin; angiotensin II; cardiomyopathy; hyperglycemia 相似文献
152.
Roadsides cover an extensive area within the United States, are actively managed, and have been considered potential areas of habitat for several taxa. For monarch butterflies (Danaus plexippus), roadsides may act as important habitat along their migration route by providing nectar and host plant resources, which is especially important considering the loss and fragmentation of monarch habitat throughout their breeding range. However, the interactions between monarchs and their parasites may be altered in these areas by management regimes. Monarchs are infected by Ophryocystis elektroscirrha (OE), an obligate, spore-forming protist of monarchs and queens, and Lespesia archippivora, a generalist tachinid fly parasitoid. Roadsides could increase parasitism by concentrating monarchs in certain areas or decrease parasitism by modifying habitat (e.g., the roadside management practice of mowing could reduce the availability of OE spores by removing the above ground portion of host plants and generating re-growth), including the distribution and abundance of host plants. In this study, we compared the proportion of infected monarchs between roadside prairies and managed prairies to evaluate the potential of roadside prairies as habitat for monarch butterflies. Our results suggest that the proportion of infected monarchs does not differ between roadside prairies and managed prairies. Thus, roadsides may provide habitat for monarchs that is similar in quality (at least in terms of parasitism rates) to managed prairies. The role of roadsides as habitat for monarchs should be considered when developing roadside management strategies. 相似文献
153.
Recognition is an important stage in the establishment of highly specific mutualistic associations. Yet, for the majority of symbioses, very few of the mechanisms involved in recognition and specificity are known. In this study, we provide evidence for a recognition mechanism at the onset of symbiosis between larvae of the coral Fungia scutaria and their endosymbiotic dinoflagellate algae. This recognition step occurs during initial cellular contact between the symbiotic partners through a lectin/glycan interaction. We determined that an intact algal cell surface was required for successful infection of F. scutaria larvae. Modification of the algal cell surface by enzymatic digestion with trypsin or N-glycosidase significantly reduced infection success, and implicated algal cell surface glycans in recognition. Using flow cytometry, alpha-mannose/alpha-glucose and alpha-galactose residues were identified as potential recognition ligands on the algal cell surface. Finally, inhibition of these cell surface glycans significantly reduced infection of F. scutaria larvae by the algae. These data provide evidence that the algal cell surface contains glycan ligands, such as alpha-mannose/alpha-glucose and alpha-galactose, which play a role in recognition during initial contact at the onset of symbiosis with F. scutaria larvae. 相似文献
154.
Ehud Banin Dimitri Vassilakos Elisha Orr Raphael J. Martinez Eugene Rosenberg 《Current microbiology》2003,46(6):0418-0422
Coral bleaching is a disease that threatens coral reefs throughout the world. The disease is correlated with higher-than-normal
seawater temperatures. Data have been reported showing that bleaching of the coral Oculina patagonica during the summer in the Mediterranean Sea is the result of an infection with Vibrio shiloi. The summer temperatures induce the expression of virulence factors in the pathogen. We report here that V. shiloi produces an extracellular superoxide dismutase (SOD) at 30°C, but not at 16°C. An SOD− mutant was avirulent. The mutant adhered to corals, penetrated into coral cells, multiplied intracellularly for a short time,
and then died. These data support the hypothesis that SOD protects the intracellular V. shiloi from oxidative stress caused by the high concentration of oxygen produced by intracellular zooxanthellae photosynthesis.
Received: 3 July 2002 / Accepted: 27 July 2002 相似文献
155.
Stoica GE Franke TF Wellstein A Czubayko F List HJ Reiter R Morgan E Martin MB Stoica A 《Molecular endocrinology (Baltimore, Md.)》2003,17(5):818-830
Previously, we have demonstrated that the two mitogenic growth factors epidermal growth factor and IGF-I can activate Akt and estrogen receptor-alpha (ERalpha) in the hormone-dependent breast cancer cell line, MCF-7. In this report we now show that estradiol can also rapidly activate phosphatidylinositol 3-kinase (PI 3-K)/Akt and that this effect is mediated by the ErbB2 signaling pathway. Treatment of cells with estradiol resulted in phosphorylation of Akt and a 9-fold increase in Akt activity in 10 min. Akt activation was blocked by wortmannin and LY 294,002, two inhibitors of PI 3-K; by genistein, a protein tyrosine kinase inhibitor and an ER agonist; by AG825, a selective ErbB2 inhibitor; and by the antiestrogens ICI 182,780 and 4-hydroxy-tamoxifen; but not by rapamycin, an inhibitor of the ribosomal protein kinase p70S6K; nor by AG30, a selective epidermal growth factor receptor inhibitor. Akt activation by estradiol was abrogated by an arginine-to-cysteine mutation in the pleckstrin homology domain of Akt (R25C). Growth factors also activated Akt in the ER-negative variant of MCF-7, MCF-7/ADR, but estradiol did not induce Akt activity in these cells. Transient transfection of ERalpha into these cells restored Akt activation by estradiol, suggesting that estradiol activation of Akt requires the ERalpha. Estradiol did not activate Akt in MCF-7 cells stably transfected with an anti-ErbB2-targeted ribozyme, further confirming a role for ErbB2. In vitro kinase assays using immunoprecipitation and anti-Akt1, -Akt2, and -Akt3-specific antibodies demonstrated that Akt1 is activated by estradiol in MCF-7 cells whereas Akt3 is the activated isoform in ER-negative MDA-MB231 cells, implying that selective activation of Akt subtypes plays a role in the actions of estradiol. Taken together, our data suggest that estradiol, bound to membrane ERalpha, interacts with and activates an ErbB dimer containing ErbB2, inducing activation of PI 3-K/Akt. 相似文献
156.
157.
Elisha W. Burr 《Mycopathologia》1981,73(1):21-23
Philippine Red Vented Cockatoos were being trapped in the wild and dispersed directly to private homes, aviarys, pet stores and for export to the United States of America. Except for non-aggressive behaviour and tiring easily the subjects showed clinically nothing peculiar. Numerous cases of Aspergillosis with no clinical signs prior to death were being reported at the United States Air Force Base, Clark Field, Angeles City, Philippines. In all cases stress was a predisposing factor to death; such as enclosure in a small bird cage. Those birds in aviarys that were kept free-flying remained clinically normal, with no deaths recorded. Systematiç examination to determine the causative source of infection was carried out and revealed natural infection in the wild state as the cause of disease in caged Red Vented Cockatoos in the Philippines. Examination on three other species of Philippine Pstitticine birds revealed only the Red Vented Cockatoo to be infected or a latent carrier in the wild state. 相似文献
158.
Travis J. Guy Matthew C. Hutchinson Katherine C.R. Baldock Elisha Kayser Benjamin Baiser Phillip P.A. Staniczenko Jacob R. Goheen Robert M. Pringle Todd M. Palmer 《Current biology : CB》2021,31(13):2964-2971.e5
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159.
Establishment and initial characterization of the ovine mammary epithelial cell line nish 总被引:4,自引:0,他引:4
Neta Ilan Itamar Barash Elisha Gootwine Moshe Shani 《In vitro cellular & developmental biology. Animal》1998,34(4):326-332
Summary Analysis of the molecular mechanisms involved in the differentiation and formation of the characteristic three-dimensional
structures of the developing mammary gland of the major milk-producing livestock (ducts, end buds, and alveoli) requires in vitro model cell cultures. The few cell lines that have been established from dairy animals do not fully reproduce the entire program
of mammary differentiation. Here we present the initial characterization of a unique mammary epithelial cell line derived
spontaneously from midpregnant sheep (NISH). These cells form in vitro functional structures resembling ducts, lateral buds, and alveoli that secrete β-lactoglobulin (BLG) in an ECM (extracellular
matrix)-dependent manner. Interestingly, the presence of growth hormone dramatically increased BLG secretion from NISH cells
cultured on ECM. It appears that GH is required not only to establish the structural organization but also is continuously
needed to maintain BLG expression. Stable transfection of NISH cells with BLG/Human Serum Albumin (HSA) hybrid gene constructs
revealed that the relative level of expression was comparable to the in vivo secretion of HSA in transgenic mice carrying these gene sequences. No expression could be detected in cells transfected with
hybrid genes carrying either HSA cDNA or the entire HSA gene, and HSA expression was dependent on the presence of intronic
sequences. These results demonstrate that NISH cells may prove a useful tool for studying the differentiation and organogenesis
of mammary epithelial cells under defined culture conditions. Furthermore, transfected NISH cells may be an alternative for
the transgenic mouse model in evaluating the potential of gene constructs to be efficiently expressed in the mammary gland
of transgenic farm animals. 相似文献
160.
Artwell Kanda France Ncube Elisha Mushati Elvis Chiboiwa Estele Mwanza Peter Makumbe 《人类与生态风险评估》2020,26(6):1663-1675
AbstractYoung children are considered critical receptors of potentially toxic trace elements (PTEs) by non-dietary ingestion of contaminated soil. The study assessed the potential enrichment of soil and the health risk of PTEs to 471 children less than seven years via non-dietary soil ingestion at six Early Childhood Development Centers (ECDCs) in urban low-income settings. The total concentrations of PTEs were determined by ICP-AES after wet acid digestion. The extent of soil contamination with PTEs and their source apportionment were assessed by the enrichment factor (EF). The US-EPA risk assessment model was used to determine the risk of PTE exposure by children. Multivariate statistical analyses and the EF suggested anthropogenic origin of PTEs in playgrounds and indoors, especially Cd and Pb from atmospheric deposition. Indoor floor dust at ECDCs was enriched (significant to extreme) with PTEs of anthropogenic origin imported from the outside environment. Children at the six ECDCs were not at significant non-carcinogenic risk of PTEs in soil and dust through non-dietary ingestion. The study setting is typical of urban child play centers in low-income countries which needs regular risk assessment and the enforcement of legislation in order to reduce the exposure of children to PTEs. 相似文献