High Al Levels Research Articles

Effect of aluminum on superoxide dismutase activity in the adult rat brain.

Male rats were treated daily with an intraperitoneal injection of 15 mg aluminum (Al chloride)/kg body weight for 17 d, in order to study the effects on superoxide dismutase (SOD) activities in the brain (cortex). No significant difference between control and treated animals was registered in the Cu/Zn and Mn SOD activities in the gray matter of the cortex. High Al levels were found in the plasma, the spleen, and the liver of the treated animals in comparison to the controls, but not in the cortex homogenates (gray matter). In addition, Al induced a significant decrease in food ingestion and weight gain.

TRACE METAL CONTENTS (AL, CU AND ZN) OF TEA : TEA AND SOIL FROM TWO TEA PLANTATIONS, AND TEA PRODUCTS FROM DIFFERENT PROVINCES OF CHINA

The present project aims to investigate the possible contamination of teas with the trace metals: Al, Cu and Zn. Tea bushes sampled from two tea plantations in the northern part of Guangdong Province accumulated higher concentrations of Cu and Zn in young leaves, and of Al in old leaves. The analysis of the three metals in tea produced in different provinces indicated higher Al levels in those obtained from Guangdong and Yunnan Provinces, which may be due to the lower soil pH in these areas. Green tea had the lowest Al concentration among the four types of tea studied, as only the bud and two young leaves are used, whereas older leaves are used for other types of tea (black, Oolong and Puerh tea). The transfer of Al, Cu and Zn from soil to different parts of tea bushes was low in general, except for Zn at Lechang tea plantation which next to a Pb/Zn mine, where a higher transfer was observed from young leaves to tea products, indicating possible metal contamination during tea processing. However, low concentrations of Cu and Zn (less than 0.07 mg Cu L-1 and 0.17 mg Zn L-1), and moderate amounts of Al (2.1-2.5 mg L-1) were obtained in the tea liquor (1% hot water extracts).

Ultrastructural Changes in Root Cap Cells of Two Australian Native Grass Species Following Exposure to Aluminium

Transmission electron microscopy was used to investigate ultrastructural changes in root cap cells of two aluminium-tolerant native grass species, Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br., following exposure to Al. Quantitative differences in root cap cells and organelles in response to 0–10 ppm aluminium were determined using image analysis of electron micrographs. Changes to the size of root cap cells due to exposure to Al were similar in the two species with a low Al concentration (1–2 ppm) resulting in larger cells, while higher Al levels (5–10 ppm) reduced cell size. In peripheral cap cells of the more Al-tolerant M. stipoides, the size of secretory vesicles was not affected by exposure to Al, while in peripheral cap cells of the less Al-tolerant D. linkii, exposure to Al resulted in significantly smaller secretory vesicles being produced. Central root cap cells from control plants of M. stipoides contained 90% more dictyosomes and had 50% larger amyloplasts than D. linkii. Measurement of mucilage droplets showed that roots of M. stipoides produced much more mucilage than D. linkii. Exposure of roots of M. stipoides to Al in the range 2–10 ppm had no effect on the size of mucilage droplets produced. The possible role of mucilage production in aluminium tolerance is discussed.

Response of ectomycorrhizal and nonmycorrhizal pitch pine (Pinusrigida) seedlings to nutrient supply and aluminum: growth and mineral nutrition

Mycorrhizal colonization and nutrient supply may have important effects on aluminum toxicity in trees grown on acidic, nutrient-poor soils. The interacting effects of mycorrhizal inoculation, nutrient level, and Al treatment on growth and mineral nutrition of pitch pine (Pinusrigida Mill.) seedlings grown with and without the ectomycorrhizal fungus Pisolithustinctorius (Pers.) Coker & Couch were determined. The seedlings were grown for 66 days in sand irrigated with 0.1- or 0.2-strength nutrient solution (pH 3.8) containing 0, 10, or 20 mg/L Al (0, 0.37, or 0.74 mM). Across nutrient and Al levels total dry weight of ectomycorrhizal (ECM) seedlings was 75% greater than that of nonmycorrhizal (NM) seedlings. Doubling the nutrient level increased the dry weight of NM seedlings by 120%, versus 60% for ECM seedlings. Aluminum reduced root and shoot growth in NM seedlings, but had no effect on shoot growth and only a marginally significant effect on root growth of ECM seedlings. Shoot growth of NM seedlings was more sensitive to Al than root growth. Increased growth of NM seedlings by doubling the nutrient level was least at the highest Al level. Symptoms of Al toxicity in roots (dark, stunted tips) occurred at a lower Al level in NM than ECM seedlings. A strong relationship was not found between Al toxicity and concentrations of Mg and Ca in roots and needles. Enhancement of growth resulting from increased uptake of nutrients due to mycorrhizal inoculation (and) or an increased level of nutrients was the overriding factor affecting the response of pitch pine seedlings to Al.

Relationships between soil solution aluminium and extractable aluminium in some moderately acid New Zealand soils

This work investigates the relationship between soil solution aluminium (Al) and extractable Al in some New Zealand soils giving high extractable Al levels, yet with pH(H2O) values ≥ 5.2. Total Al in 1 M KCl extracts ranged from 0.8 to 11.6 cmol(+)/kg, and in corresponding 0.02 M CaCl2 extracts from 0.002 to 0.39 cmol(+)/kg. Soil solutions had low total Al concentrations, ranging from < 0.5 to 12.5 µM, with < 10% of the Al in the monomeric Al form as determined by the chromeazurol S colorimetric method. There was a poor correlation between Al in soil solution and that extracted by either 1 M KCl or 0.02 M CaCl2. The measured monomeric Al concentrations in the soil solutions did not exceed levels corresponding to Al toxicity threshold activities set at 10 or 2 µM, related to a range of pasture plant tolerances, whether based on the activity of Al3+ species alone, or on the sum of the individual activities of Al3+, Al(OH)2+ and Al(OH)2+ species. The high 1 M KCl-extractable and 0.02 M CaCl2-extractable Al values provided a misleading indication of potential Al toxicity status, probably due to the generation of artificially high extracted Al concentrations from these particular types of soils.

Aluminum content of infant formulas used in Turkey

In the past few years, there has been an upsurge of interest in aluminum (Al) and human health. The well-recognized manifestations of systemic Al toxicity include fracturing osteomalacia, dialysis encephalopathy, and microcytic hypochromic anemia. The role of Al in causing childhood diseases is also becoming clearer, but the safe plasma level still remains to be determined in newborns, especially in premature newborns, implying that it should be kept low. Premature infants receiving iv fluid therapy show evidence of Al loading. Additionally, the infant-feeding mixtures, especially the soy-based infant formulas, tested may be a significant additional source of Al in the diet of infants with low birthweights, and in infants and in young children with impaired renal function. Careful clinical and biochemical monitoring is warranted to determine whether it will be necessary to eliminate Al contamination of both oral and parenteral preparations used in infants and children who may be at risk for Al intoxication. In this present study, the Al content of infant feeds was measured by electrothermal atomic absorption spectrophotometry, and also compared with those of breast milk, cow's milk, milk powder, and some starches that are commonly used for preparation of infant feed in Turkey. Our results show that Al content of commercially available powdered infant formulas, most of which are imported from Europe, ranged from 1.211 to 10.925 micrograms/g. The mean value was higher than that of breast milk. It was also found that the Al content of cow's milk in various containers was higher than that of breast milk. The highest Al level among cow's milk samples was in the aluminized carton box.

INAA multielemental analysis of Nigerian bituminous coal and coal ash

Instrumental neutron activation analysis (INAA) was used to analyzed Nigerian bituminous coal and ash. Good statistical agreement (p≤0.05) between the literature and reported elemental values of USGS AGV-1 sample was found. Many elements were determined in the coal with some enrichment in the coal ash. Arsenic was measured only in the ash while Hg was present only in the coal. Coal ashing at 800°C contributed to a loss of Hg in the ash. Al, Na, Mg, Ti, Fe, which are major elements were found in the coal as expected, with slight enrichment in the ash. Ca and Si were only obtained in the ash. High ash Al (14.9±0.19%) and Si (25.3±4.11%) levels are of concem due to possible cases of pneumononiosis from inhalation of the particulates. Graphical illustration of the lanthanide concentrations peaked at Ce with a decrease from Sm to Lu. U and Th were also present in the samples showing slight enhancement in the ash. Comparatively low coal elemental values, notably S(1.8%), highly advocate this coal as a good quality fuel-coal.

Geochemical Risk Factors for Mental Functioning, Based on the Ontario Longitudinal Study of Aging (LSA) IV. The Role of Silicon-Containing Compounds

AbstractFollowing previous studies on the associations between aluminium (Al) water concentrations and relatively high risks of a measure of mental impairment, the role of silica (SiO2) as a possible confounding variable is investigated. The bivariate associations show that the lowest odds, representing an approximation of relative risks, are observed at “mild” SiO2concentrations. Multivariate analyses indicate that, if interaction terms are included, the odds comparing higher and lower SiO2concentrations are different than if an interaction term is not included. There are also indications that at relatively high Al levels, high SiO2concentrations lower the odds, consistent with previous suggestions by Birchall. The implication is that when investigating the role of Al in the etiology of various measures of mental impairment, it is important to consider the effects of other water constituents, and also the different chemical forms of Al present in treated water. The desirability of additional work is stressed, preferably using more definitive outcomes than indications of mental impairment.

Suppression of the toxic effect of soluble aluminium on fungi by dermocybin‐1‐β‐D‐glucopyranoside and orellanine from Cortinarius sanguineus and C. orellanoides

Extracts of Cortinarius sanguineus — containing anthraquinones — and C. orellanoides — containing orellanine — were examined for their ability to suppress the toxicity of aluminium ions by a bioassay experiment using the saprotrophic basidiomycete Mycena septentrionalis as the test organism. The aluminium concentrations used were: 0, 0.5,0.5e1, 0.5e2,0.5e3, and 0.5e4 mM Al. All were given as aluminium sulphate, with or without the extract of Cortinarius sanguineus or C. orellanoides. The extract of C. sanguineus suppressed the toxic effect of Al up to 0.5e3 mM. The C. orellanoides extract inhibited growth of the test organism up to 0.5e1 mM Al and suppressed the toxic effect of Al up to 0.5e3 mM Al. Mycena septentrionalis grew rapidly in 0.5e2 and 0.5e3 mM Al. Chromatographic investigations indicated that Al was mainly bound to dermocybin‐1‐ß‐D‐glucopyranoside, but not to anthraquinone aglycones in the C. sanguineus extract. Corresponding procedures for the C. orellanoides extract revealed that Al was bound to orellanine (and orelline). Orellanine may form an Al‐complex polymer at moderate Al levels and an Al‐chelate at high Al levels. Aluminium removed the toxic effect of orellanine. The significance of a possible Al detoxifying mechanism for the tested fungi in nature is discussed.

Spectral editing: A quantitative application of spin-echo nuclear magnetic resonance spectroscopy to the study of 27Al in zeolite catalysts

27Al spin-echo nuclear magnetic resonance (n.m.r.) is used to measure the spin—spin relaxation times, T 2H, for a substantial number of model compounds, and a theory (with no adjustable parameters) based on AIAI dipolar interactions combined with crystallographically determined AIAI distances is used to estimate T 2H. The homonuclear magnetic dipole interaction explains the experimental data reasonably well for compounds with high Al levels, but much less well for compounds with low levels of AI, where structure-specific interactions are important. Such structure-specific interactions are exploited to edit zeolitic AI from the background binder in alumina-bound ZSM-5 and in dealuminated zeolite-Y catalysts containing nonframework (NFW) AI. Editing allows quantitative analysis of the zeolitic components. For dealuminated zeolite Y, it is concluded that peaks assigned by others to “pentacoordinate” AI may actually arise from NFW aluminum, based on the fact that their T 2H is short relative to framework (FW) AI. Theory and experimental results for the technically more demanding measurement of T 2H under conditions of “magic-angle” sample spinning ( MAS) with synchronous sampling are also reported. Spin-echo editing of synchronously sampled 27AI MAS n.m.r. spectra are shown to be useful for determining the FW zeolitic AI content of realistically formulated (kaolinite bound) and steamed/calcined fluidized bed cracking (FCC) catalysts. The loss of framework AI in two series of steamed FCC catalysts is less precipitous than the loss in catalytic activity, as measured by the hexane cracking α parameter.

Auger Electron Spectroscopy Study of Grain Boundary Segregation in Alloy K-500: Part I. Behavior in As-Processed State

Increased interest has been paid to grain boundary segregation in alloy K-500 due to severe intergranular cracking recently observed in forged bars. However, little systematic study of this segregation has been performed so far. A detailed auger electron spectroscopy (AES) study of grain boundary segregation in alloy K-500 has been carried out as a function of alloy chemistry. To determine C segregation, the C and O contamination rates in a vacuum chamber were measured and the necessary condition for C grain boundary segregation determination was established. It has been found that severe C, Al, and Cu segregation to grain boundaries occurred and depended on alloy chemistry. High bulk Ni and low bulk Al promoted C and Al grain boundary segregation, and low bulk Ni and high bulk Al significantly enhanced Cu segregation to grain boundaries. The depth profiles of intergranularly segregated elements also showed different features for high and low Ni content alloys. In high Ni alloys, C and Al levels dropped continuously as a function of distance from the grain boundaries but the Cu level dropped only slightly. In low Ni alloys, the Al and C levels rose from relatively low grain boundary levels to a peak at a certain distance from the grain boundary where the high grain boundary Cu level dramatically dropped. Transmission electron microscope (TEM) observation revealed a grain boundaryγ′-depleted zone followed by a region with coarser and denserγ′ particles in low Ni and high Al alloys but quite uniformly distributedγ′ particles with no depleted zone in high Ni and low Al alloys. These can be explained by the observed segregation behavior. The occurrence of Cu segregation is explained according to available theories about surface segregation in binary Ni-Cu alloys, and the segregation of C and Al to grain boundaries is suggested to be probably due to their interaction with Ni and Cu.

Mortality of Brook Trout, Mottled Sculpins, and Slimy Sculpins during Acidic Episodes

Abstract Brook trout Salvelinus fontinalis, mottled sculpins Cottus bairdi, and slimy sculpins Cottus cognatus occur in many Pennsylvania streams that have depressed pH and elevated aluminum concentrations during episodes of high stream discharge (acidic episodes). We performed 20-d in situ cage exposures with these species to determine their relative sensitivities to field conditions. We also exposed fish in the laboratory to synthetic soft water, without added Al, to elevate possible effects of Al on sodium flux rates and pH toxicity. Exposures were in five streams: Two with high pH (>5.60) and low Al concentrations (<80 μg/L) and three with low pH (usually between 5.0 and 5.5) and high Al levels (124–294 μg/L). Exposures were during two low-discharge fall periods, when pH tends to be seasonally higher and Al concentrations lower, and two relatively high-discharge spring seasons, when lower pH and higher Al concentrations are typical. Few fish died (generally < 10%) in the two streams that had higher pH...

Aluminum Effects on Calcium Uptake and Translocation in Wheat Forages

AbstractThe effects of Al on Ca transport could influence Ca accumulation in plants. Low forage Ca concentrations may cause hypocalcemia, a Ca deficiency syndrome of ruminants. Solution culture experiments were conducted in a growth chamber to examine the effects of Al (5–50 μM on uptake and translocation of Ca (45Ca) in winter wheat (Triticum aestivum L.) cultivars (Al‐tolerant Atlas 66 and Al‐sensitive Scout 66). Three‐day‐old seedlings, grown either in a CaCl2 solution (0.1 or 1.0 mM) or in a complete‐nutrient solution, were used. For plants grown in CaCl2 solution, addition of 5 μM Al significantly decreased Ca uptake and translocation in Scout 66, but not in Atlas 66. Higher levels of Al (20 and 50 μM) decreased Ca uptake and translocation much more in Scout 66 than in Atlas 66. For plants grown in complete‐nutrient solution, Al (5–50 μM) exposure for up to 6 h had little effect on Ca uptake and translocation in either cultivar. This may be due to the reduction in Al3+ activities in the external solution, as well as lowered Al3+ activities near the root‐cell plasmalemma. When roots were exposed to Al for 24 h, Ca uptake and translocation were decreased significantly in Scout 66, but were little affected in Atlas 66. The percentage of Ca translocated to the shoots was significantly decreased by Al in Scout 66, but not in Atlas 66. These results suggest that Al inhibits both Ca uptake and translocation in Scout 66, but inhibits primarily root Ca uptake in Atlas 66 (and only at higher Al levels). It appears that the use of Al‐tolerant cultivars of wheat forages on acid soils could be important for maintaining proper Ca nutrition of grazing animals.

Emergence and growth of two non-nodulated soybean genotypes (Glycine max (L.) Merr.) in response to soil acidity

Toxic levels of extractable soil Al limit production of important crops in many areas of the world. The nature of the limitation in soybeans is not completely understood. Our objectives were to investigate the cause of acid-soil-induced delays in seedling emergence, the effect of acidity on productivity in non-nodulated soybeans and further test the Al tolerance of PI 416,937 compared to a sensitive control, Essex. Growth characteristics of the two genotypes through the flowering stage were measured on a Corozal clay (Aquic Tropudult) in Puerto Rico which had been differentially limed to provide a wide range of soil Al. Early growth was also studied in the laboratory using soil from the field experiment. Highly acidic soil conditions, coupled with high Al levels, reduced growth in both Essex and PI 416,937. The principal factor responsible for delayed emergence in the high Al soil was not delayed radicle initiation, but delayed initiation of hypocotyl elongation. Hypocotyl initiation was highly associated with rate of tap root growth, with the former possibly determined by the latter, because a minimum tap root length of 60 mm was required in both high and low Al soils before hypocotyl initiation commenced. In seedlings, the high acidity reduced root more than shoot growth. By 44 days after planting (DAP), however, soil acidity had reduced shoot growth greatly. Although the soybean plants were not nodulated, foliar N levels and shoot growth were decreased by high Al levels, indicating that interference with N fixation may not be the sole mechanism by which nitrogen accumulation and plant growth is reduced in the field.

Dissolved aluminium in the surface microlayer of the eastern Arabian sea

Measurements of dissolved aluminium (Al) in surface microlayer (SML) samples from the eastern Arabian Sea during the southwest (summer) and northeast (winter) monsoon periods have revealed much higher concentrations (23–657 nmol kg −1) than in the sub-surface layer (SSL; collected at 1 m depth). Higher concentrations observed during the summer monsoon and directional trends in the distribution, with concentration maxima situated away from the influence of fluvial discharge, are best explained by the atmospheric deposition of mineral dust aerosol and its subsequent dissolution in the surface seawater. The low Al concentrations in the SSL (11–296 nmol kg −1) varied in line with those in the SML. However, Al was significantly higher there than in the rest of the water column (up to 3000 m), indicating that much of the dissolved aerosol Al was removed in the upper few metres of the water column. The non-nutrient-type behaviour of dissolved Al did not support a mechanism of Al removal by biological uptake. High Al levels in the SML observed during the summer monsoon were associated with low primary productivity. The considerably lower values observed during the winter monsoon, a period of higher primary productivity in the Arabian Sea, could be due to removal from solution by adsorption onto biogenic particles.

Alterations in intracellular calcium and tension of activated ferret papillary muscle in response to step length changes.

1. To study the effects of mechanical constraints on the calcium (Ca2+) affinity of cardiac troponin C, we analysed the tension and aequorin light (AL, intracellular Ca2+) transients in response to a step length change in aequorin-injected ferret right ventricular papillary muscles. The muscle preparations were continuously activated with ouabain (10(-4) M) (ouabain contracture) or with high frequency stimuli in the presence of ryanodine (5 microM) (tetanic contraction). 2. The tension transient in response to either the release or stretch was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in ouabain-activated preparations (oscillation frequency of 2.2-2.3 Hz at 22 degrees and 4.5-4.6 Hz at 30 degrees C) and much more damped in ryanodine-treated preparations. 3. The transient AL response was also oscillatory, the time course of which corresponded to that of the transient tension response. Regardless of the difference in the time course of the transients in two different preparations and at two different temperatures, the increase in AL corresponded to the decrease in tension, likewise the decrease in AL to the increase in tension. 4. The mean level of AL after release was lower than the control level present just prior to the release in ouabain-activated preparations, but the AL after release finally returned to the nearly control level in ryanodine-treated preparations. 5. When the ryanodine-treated muscle was further treated with 2,3-butanedione monoxime (BDM) (20 mM), the tetanic tension decreased remarkably without affecting the AL signal. The tension transient of this preparation was quite similar to that of the resting muscle, which changed in a nearly stepwise fashion; AL was hardly affected by step length changes, as in the resting muscle, in spite of the higher AL level. 6. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e. the cross-bridge attachment) and decreased with a decrease in tension i.e. the cross-bridge detachment), and that the mean [Ca2+]i is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.

Neurocognitive effects of aluminum.

The neurocognitive effects of aluminum (Al) were studied in 35 hemodialysis patients. Higher Al levels were associated with a decline in visual memory. As Al levels increased, patients with lower vocabulary scores (a measure of premorbid intelligence) showed a decline in attention/concentration, frontal lobe functions, and on several neurocognitive measures, while those with higher vocabulary scores revealed no Al-related decline. These results suggest that individuals with lower verbal intelligence may possess less well-developed compensatory strategies to overcome the neurocognitive effects associated with Al. These data also indicate that Al is neurotoxic and, therefore, potential sources of environmental Al should be identified and eliminated.

Nutritional differentiation among populations of the mediterranean shrub Dittrichia viscosa (Asteraceae) in siliceous and calcareous habitats.

Dittrichia (ex Inula) viscosa is a ruderal species that has recently become an invading plant in the northwest Mediterranean basin. A previous study failed to demonstrate the occurrence of morphologically differentiated ecotypes among populations of the species but suggested the existence of nutritional ecotypes. This latter possibility is examined here by comparing the ability of plants from contrasting habitats to control cation accumulation balance. Dittrichia viscosa plants, from eight siliceous habitats and nine calcareous habitats of southern France and neighbouring Spain and Italy, were cloned and grown together hydroponically with a solution simulating an acid soil with an aluminium constraint. Two independent hydroponic units containing solution supplemented with two levels of Al were used (2 Al levels x17 populations x3 genotypes x3 replicates). The growth and cation content (K, Ca, Mg and Na) of plant shoots and the chemical composition of the soil of each habitat were analysed. At the high Al level (1.1MM), populations differed in K, Ca and Mg plant proportions. Two groups could be distinguished: one containing all but one siliceous populations and the other containing all but one calcareous populations. Plants of the siliceous group accumulated proportionally more K and less Ca, and had better growth, than plants of the calcareous group, in the same way as calcifuge and calcicole species when grown on acid soil. At the lowest Al level (0.37MM), differences between siliceous and calcareous populations were less marked. The results suggest that differences in the ability of plants to control K and Ca balance, which appear to be of adaptive significance, could have arisen through selection, and that Dittrichia viscosa has evolved calcifuge and calcicole nutritional ecotypes in siliceous and calcareous habitats respectively. Various degrees of calcifugy, and to a lesser extent of calcicoly, can thus be suggested to occur among the studied populations, some in relation to the intensity of mineral stress in the natural habitats. So far, only functional traits have provided evidence of ecotypic differentiations within Dittrichia viscosa.

The effect of pH, aluminum, and chelator manipulations on the growth of acidic and circumneutral species of Asterionella

The growth rates of two diatoms, acidophilic Asterionella ralfsii and circumneutral A. formosa, were differentially affected by varying pH, Al, and EDTA in chemically defined media. Free Al ion concentration increased as pH and EDTA concentration decreased. Free trace metal ion concentration decreased as EDTA levels increased but increased by orders of magnitude upon addition of Al. pH had an overriding species specific effect on growth rate; at low pH A. ralfsii had higher growth rates than A. formosa and vice versa at high pH. For both species higher EDTA levels depressed growth rates. Moderate additions of Al generally resulted in growth stimulation. The growth rate stimulations, especially at 200 and 400 μg L−1 Al additions, correlate to increases in free trace metal ion concentrations. The EDTA-AI interaction effects on growth rate were both pH and concentration dependent: at pH 7 both species were stimulated by addition of Al at all EDTA levels (except A. ralfsii at 5.0 mM EDTA and A. formosa at 0.5 mNM EDTA); at pH 6 Al addition either stimulated or had no effect on the growth rates of both species (except at low EDTA and high Al levels); at pH 5 A. formosa did not grow and additions of 200 μg L−1 Al stimulated growth of A. ralfsii. It is likely that the effect of pH, Al, and EDTA on speciation of essential or toxic trace metals affects growth rates of these diatoms in a species specific manner.

Interaction of aluminium and gallium with human lymphocytes: the role of transferrin

Aluminium-transferrin (Al-Tf) and gallium-transferrin caused a dose-dependent decrease in proliferation of human peripheral blood lymphocytes cultured for 3 days with phytohaemagglutinin (PHA). Addition of apotransferrin reduced the inhibitory. Al added as AlCl 3 or aluminium citrate had no effect, and there was no significant difference in the response of cells from renal failure patients with or without high serum Al levels or controls. Lymphocytes cultured in the presence of Al-Tf showed a dose-dependent uptake of Al, whereas uptake from aluminium citrate was low and not dose-dependent. Uptake from AlCl 3 was very high but probably involved a nonspecific uptake mechanism. Levels of Al in freshly isolated lymphocytes were approximately 1.6 ng/10 6 cells, there being no difference between cells from patients and controls. It is concluded that Al, when bound to transferrin, may have a detrimental effect on lymphocyte function and might contribute to the decreased immune responsiveness of renal failure patients on haemodialysis. However, lymphocyte Al levels are probably not useful as a marker of Al overload in such patients.