PubMed · 4622872
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J C Jones. 1972. Electron beams.. https://pubmed.ncbi.nlm.nih.gov/4622872/
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BACKGROUND: Aluminum, a contaminant of commercial intravenous-feeding solutions, is potentially neurotoxic. We investigated the effect of perinatal exposure to intravenous aluminum on the neurologic development of infants born prematurely. METHODS: We randomly assigned 227 premature infants with gestational ages of less than 34 weeks and birth weights of less than 1850 g who required intravenous feeding before they could begin enteral feeding to receive either standard or specially constituted, aluminum-depleted intravenous-feeding solutions. The neurologic development of the 182 surviving infants who could be tested was assessed by using the Bayley Scales of Infant Development at 18 months of age. RESULTS: The 90 infants who received the standard feeding solutions had a mean (+/-SD) Bayley Mental Development Index of 95+/-22, as compared with 98+/-20 for the 92 infants who received the aluminum-depleted solutions (P=0.39). In a planned subgroup analysis of infants in whom the duration of intravenous feeding exceeded the median and who did not have neuromotor impairment, the mean values for the Bayley Mental Development Index for the 39 infants who received the standard solutions and the 41 infants who received the aluminum-depleted solutions were 92+/-20 and 102+/-17, respectively (P=0.02). The former were significantly more likely (39 percent, vs. 17 percent of the latter group; P=0.03) to have a Mental Development Index of less than 85, increasing their risk of subsequent educational problems. For all 157 infants without neuromotor impairment, increasing aluminum exposure was associated with a reduction in the Mental Development Index (P=0.03), with an adjusted loss of one point per day of intravenous feeding for infants receiving the standard solutions. CONCLUSIONS: In preterm infants, prolonged intravenous feeding with solutions containing aluminum is associated with impaired neurologic development.
Transmission electron microscope observations of the Allende carbonaceous chondrite provided evidence of widespread hydrous phases replacing enstatite in chondrules. Calcic amphibole and talc occur in thin (less than 0.3 micrometer) crosscutting veins and as alteration products of primary chondrule glass in contraction cracks within the enstatite. In addition, talc and disordered biopyriboles were found replacing enstatite grains along cracks and fractures. Although rare hydrous phases have been reported in calcium- and aluminum-rich inclusions in the Allende meteorite, these observations suggest that aqueous fluids played a much more significant role in the mineralogical and geochemical evolution of Allende than has previously been thought.
In an effort to understand the biochemical mechanisms of aluminum-induced neurotoxicity, we investigated the effects of aluminum ion, Al3+, on the Mg(2+)- and nucleotide-dependent protein, ras p21. Picomolar Al3+ concentrations inhibited the GTPase activity of ras p21 in an Mg(2+)-dependent manner, consistent with an Al3+/Mg2+ competition mechanism. GTPase activity was inhibited by 60% in the presence of 100 microM Mg2+ and 2.9 x 10(-10) M Al3+. Kinetic studies demonstrated that the mode of Al(3+)-induced inhibition of ras p21 GTPase activity changed from competitive to mixed non-competitive as the number of ras p21 turnovers increased. Further dissection of the ras p21 cycle revealed that Mg(2+)-dependent GDP/GTP exchange was the Al(3+)-sensitive step.