PubMed · 6599650
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
M Viti, A Mazza, G E Solimei. [Interaction between various trace elements (II)].. https://pubmed.ncbi.nlm.nih.gov/6599650/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Aluminum is extremely common throughout the world and is innocuous under circumneutral or alkaline conditions. However, in acidic environments, it can be a major limiting factor to many plants and aquatic organisms. The greatest concern for toxicity in North America occurs in areas that are affected by wet and dry acid deposition, such as eastern Canada and the northeastern U.S. Acid mine drainage, logging, and water treatment plant effluents containing alum can be other major sources of Al. In solution, the metal can combine with several different agents to affect toxicity. In general, Al hydroxides and monomeric Al are the most toxic forms. Dissolved organic carbons, F, PO(3)3- and SO(4)2- ameliorate toxicity by reducing bioavailability. Elevated metal levels in water and soil can cause serious problems for some plants. Algae tend to be both acid- and Al tolerant and, although some species may disappear with reduced pH, overall algae productivity and biomass are seldom affected if pH is above 3.0. Aluminum and acid toxicity tend to be additive to some algae when pH is less than 4.5. Because the metal binds with inorganic P, it may reduce P availability and reduce productivity. Forest die-backs in North America involving red spruce, Fraser fir, balsam fir, loblolly pine, slash pine, and sugar maples have been ascribed to Al toxicity, and extensive areas of European forests have died because of the combination of high soil Al and low pH. Extensive research on crops has produced Al-resistant cultivars and considerable knowledge about mechanisms of and defenses against toxicity. Very low Al levels may benefit some plants, although the metal is not recognized as an essential nutrient. Hyperaccumulator species of plants may concentrate Al to levels that are toxic to herbivores. Toxicity in aquatic invertebrates is also acid dependent. Taxa such as Ephemeroptera, Plecoptera, and Cladocera are sensitive and may perish when Al is less than 1 mg.L-1 whereas dipterans, molluscs, and isopods seem to be tolerant. In Al-sensitive species, elevated levels (approximately 500 micrograms.L-1) affect ion regulation and respiratory efficiency. Toxicity tends to be greatest near a species' threshold of pH sensitivity. At lower pHs, Al may have a slight ameliorative effect by interfering with H+ transport across membranes. Aquatic invertebrates can accumulate very high levels of Al, but most of this appears to be through adsorption rather than assimilation. Aluminum concentrations may be as high as 5000 mg.kg-1 in insects and greater than 17,000 mg.kg-1 in other invertebrates.(ABSTRACT TRUNCATED AT 400 WORDS)
The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively.
Amylin is co-secreted with insulin from the pancreas of patients with non-insulin dependent diabetes mellitus, and its deposition may contribute to the central nervous system (CNS) manifestations of this disease. Amylin, but not its mRNA, is found in brain, suggesting that CNS amylin is derived from the circulation. This would require amylin to cross the blood-brain barrier (BBB). We used multiple-time regression analysis to determine the unidirectional influx constant (Ki) of blood-borne, radioactively labeled amylin (I-Amy) into the brain of mice. The Ki was 8.99(10(-4)) ml/g-min and was not inhibited with doses up to 100 micrograms/kg, but it was inhibited by aluminum (Al). About 0.11 to 0.13 percent of the injected dose of I-Amy entered each gram of brain. Radioactivity recovered from brain and analyzed by HPLC showed that the majority of radioactivity taken up by the brain represented intact I-Amy. Capillary depletion confirmed that blood-borne I-Amy completely crossed the BBB to enter the parenchymal/interstitial fluid space of the cerebral cortex. Taken together, these results show that blood-borne amylin has access to brain tissue and may be involved in some of the CNS manifestations of diabetes mellitus.