Search

Adsorbing Colloid Flotation (ACF) has been shown in laboratory experiments to be effective for the removal of heavy metals (Zn, Cu, Cd and Pb) from dilute solutions. Sodium dodecyl sulphate (SDS) and sodium oleate (NaOl) were used as surfactants in single or mixed form, with Fe(OH) 3 as a flocculant for colloid formation. These reagents worked best for zinc and copper ions for a feed concentration of 50 parts per million (ppm). The removal of lead improved significantly by the use of Fe(OH) 3 and NaLS (Sodium lauryl sulphate), while the best removal of cadmium was achieved by the use of Al(OH) 3 and HTMABr (hexadecyltrimethylammonium bromide). Flotation experiments were conducted with feed concentrations of 50 and 500 parts per billion (ppb) and 50 ppm (parts per million). The experimental results showed that the residual concentration of metal ions decreased significantly with the decrease in the feed concentration. This could be the effect of excessive (much more than stoichiometric ratio) amounts of surfactant and flocculant, compared to the feed concentrations, required in the effective flotation of dilute feed solutions. The surfactant concentration and feed pH had the largest effects on the process, as observed in the case of cadmium removal. This can be attributed to the floc formation and flotation tendencies of the colloid-metal complexes at various solution pH and surfactant concentrations. The ACF method was applied to a number of natural drainage solutions from the metal mines at Te Aroha, New Zealand, and the experimental results demonstrate that significant removal is achieved for most of the heavy metals.

Binding of the class III antiarrhythmic agent azimilide to brain, heart, and other organ receptors was assessed by standard radioligand binding techniques. In a survey of 60 receptors, azimilide at 10 μM inhibited binding by more than 50% at serotonin uptake ( K i : 0.6 μM), muscarinic ( K i : 0.9 to −3.0 μM), Na + channel site 2 ( K i : 4.3 μM), and central sigma ( K i : 6.2 μM) sites. Lesser (20–40%) inhibition was seen at adrenergic, histamine, serotonin, purinergic, angiotensin II, dopamine uptake, and norepinephrine sites and at a voltage-sensitive K + channel. In rat ventricle, azimilide inhibited binding to α 1 - and β-adrenergic and muscarinic receptors ( K i : 2+ channel ( K i : 37.3 μM). In rat brain, azimilide blocked ligand binding to these same receptors and to a serotonin receptor, and the breadth and potency of its interaction pattern differentiated it from ten other class III antiarrhythmics. Azimilide displayed agonist and antagonist action at five muscarinic receptor subtypes in transfected NIH 3T3 cells producing receptor-sensitive mitogenesis and β-galactosidase activity. Agonist action predominated at M 2 and M 4 subtypes, and antagonist action predominated at M 1 , M 3 , and M 5 subtypes. The azimilide concentration for 50% maximum stimulation ( ec 50 ) in M 2 -expressing cells was 1.97 μM (vs 0.14 μM for carbachol). Azimilide’s receptor interactions occur at concentrations from one to forty times those required to block cardiac delayed-rectifier channels but could contribute to the efficacy and safety of the drug.

Azimilide and Dofetilide Atrial Flutter Efficacy.Introduction: Azimilide dihydrochloride blocks both the rapid (IKr) and slow (IKs) components of the delayed rectified K+ current; dofetilide blocks only IKr. Their efficacies were assessed on atrial flutter reentrant circuits in dogs with surgically induced right atrial enlargement. Methods and Results: Multiple biopsies of the tricuspid valve and banding of the pulmonary artery in male mongrel dogs made them susceptible, about 3 weeks postoperatively, to stimulation-induced sustained (5 min or longer) atrial flutter. Azimilide 3 mg/kg administered intravenously (IV) terminated flutter in 8 of 8 dogs, but a slower, nonsustained arrhythmia could be reinduced in 5. In these 5 dogs, azimilide 10 mg/kg terminated flutter and prevented reinduction. This dose increased effective refractory period significantly more in the slow conduction zone (25%) than in the normal zone (17%) and increased flutter cycle length (37%). Termination followed progressive conduction delay in the slow zone of the reentrant circuit. Dofetilide 1 μg/kg IV terminated flutter in 6 of 6 dogs, but the arrhythmia could be reinduced. At 3 μg/kg, flutter terminated in all dogs and could not be reinduced. Dofetilide also increased the effective refractory period significantly more in the slow zone (17%) than in the normal zone (12%) and increased cycle length (33%), leading to interruption of the arrhythmia circuit. Conclusion: In the canine right atrial enlargement model of circus movement atrial flutter, both azimilide 10 mg/kg IV and dofetilide 3 μg/kg IV were 100% effective in terminating flutter and preventing reinduction. Efficacy relied on a similar mechanism of differentially prolonged refractoriness in the slow conduction component of the reentrant circuit where drug-induced termination occurred.

Eleven common vegetables (green bean, beetroot, green cabbage, lettuce, onion, pea, radish, spinach, tomato, turnip, and watercress) as well as the thallium hyperaccumulator Iberis intermedia, were grown in pot trials containing 0.7 and 3.7 mg/kg thallium added to a silt loam soil. The aims of the experiments were threefold: to estimate risks to human health of vegetables grown in thallium-rich soils, to demonstrate the potential of crops of these plants to remove thallium from polluted soils (phytoremediation), and finally to establish the degree to which part of the costs of remediation could be recouped by selling the extracted thallium (phytomining). Maximum thallium levels ranged from nearly 400 mg/kg (d.m.) in Iberis down to just over 1 mg/kg in green bean. The four vegetables with the highest thallium levels (watercress, radish, turnip and green cabbage) were all Brassicaceous plants, followed by the Chenopods beet and spinach. At a thallium concentration of 0.7 mg/kg in the soil only green bean, t...

Elsholtzia haichowensis Sun and Commelina communis L. are the most widely distributed heavy-metal-tolerant plants in the areas along the middle and lower streams of the Yangtze River, China. Both plant species were grown in pot trials involving three different treatments containing 3–12 mg kg−1 cadmium (Cd), 37–140 mg kg−1 copper (Cu), 30–101 mg kg−1 chromium (Cr)

The current environmental impact of base metal mining at the Tui Mine, Te Aroha and gold mining near Waihi, was investigated by analysis of local waters, stream sediments, and aquatic vegetation X‐ray diffraction analysis of heavy metal fractions in stream sediments showed the presence of pynte in the upper reaches of the Tunakohoia and Tui Streams that drain the mineralised reefs and Tui tailings dam Relatively immobile lead (galena) was retained close to the source, whereas copper and zinc minerals were more mobile and distributed further downstream from the areas of mineralisation Gold was determined in sediments from the Ohinemun and Waitekaun Rivers along with other heavy metals derived from sulphide mineralisation at Waihi and Waitekaun Analysis of waters from the Tui and Tunakohoia Streams showed concentrations of arsenic, cadmium, lead and zinc above recommended levels for potable water in the upper parts of these waterways The discharge of these streams into the Waihou River (sampled upstream fro...

The uptake of cobalt, copper, lead, and nickel by the perennial metal‐tolerant grass Arrhenatherum elatius was studied by growing the plants in two different substrates. These were a cobalt/copper/nickel ore (Experiment A) and base‐metal tailings rich in lead (Experiment B). The enhancement of metal uptake by the plants following addition of EDTA was investigated in both experiments. In Experiment A, metal concentrations in dry plant matter were about equal to the acid‐extractable (1 M hydrochloric acid) fractions in the supporting soils after addition of 4 g kg‐1 EDTA. In Experiment B, the base‐metal tailings contained 11,500 mg kg‐1 (1.15%) lead. The EDTA addition induced 2.5% lead (dry matter) in the grass. This was reduced to ca. 1.0% upon addition of lime. The results indicate that A. elatius may have some potential in phytoremediation operations if EDTA is added to the substrate.

Plants with inordinately high concentrations of heavy metals (‘hyperaccumulators’) can be used for phytoremediation (removal of contaminants from soils) or phytomining (growing a crop of plants to harvest the metals). Pot trials were used to investigate the effects of MgCO3, CaCO3, sulphur, chelating agents (NTA, DTPA, EDTA) and acid mine tailings on nickel and cobalt uptake by the South African nickel hyperaccumulator Berkheya coddii. Plants were grown in a nickel-rich ultramafic (‘serpentine’) soil diluted with pumice. Both MgCO3and CaCO3caused significant decreases in the uptake of both metals, as well as decreasing their solubility in the soil. After the addition of MgCO3,there was a significant increase in soil pH, so the reduction in plant-metal uptake could not be solely attributed to the action of magnesium alone. Since CaCO3had no significant effect on soil pH, this indicated that calcium inhibits the uptake of both cobalt and nickel. All three chelating agents caused a significant reduction in plant uptake of nickel, despite increasing the solubility (plant availability) of these elements in the soil. Cobalt uptake was unaffected. Sulphur, and the addition of acid mine tailings, caused a highly significant increase in nickel and cobalt uptake, relative to the controls. Sulphur could be used as a low-cost soil amendment to enhance the metal uptake of crops grown on ultramafic soils. Thus, land management procedures would enhance phytoremediation and phytomining operations for nickel and cobalt.

Biscutella laevigata and Iberis intermedia were sampled from sites near St Laurent le Minier, Southern France, and B. laevigata was also sampled from Rocca San Silvestro, Tuscany, Italy. Soils associated with the rhizosphere of each plant were also sampled. Both Biscutella laevigata and Iberis intermedia accumulate inordinately high concentrations of thallium (1.94 and 0.4%, respectively) in their above-ground dry tissue. The levels of thallium accumulated by both species were strongly correlated with both the total and extractable concentrations of thallium in the soils. Concentrations of zinc, cadmium, and lead were below the threshold for hyperaccumulation. It is proposed that B. laevigata and/or I. intermedia could be used for phytoremediation or phytomining of thallium-contaminated soils. Such an operation would involve the repeated cropping of either species, until an acceptable level of thallium in the soils was reached. Additionally, the harvested plant material could be burnt and the res...

This review covers three aspects of gold uptake by plants: passive uptake by wild plants under natural conditions; hydroponic studies on plants grown in solutions of gold salts; induced hyperaccumulation of gold by plants grown in auriferous substrates using ammonium thiocyanate as a chelating agent. Using induced hyperaccumulation, it is proposed that it would be technically feasible to grow ‘a crop of gold’ usingBrassica juncea or other plant species.

Pot trials and chemical analyses were carried out on wild specimens of Erica andevalensis Cabezudo et Rivera (Ericaceae) and their associated soils. Natural soils hosting E. andevalensis all had elevated copper concentrations. Pot trials showed that the Erica would grow in sulphide‐ore substrates containing up to 12,500 μg g‐1 (1.25%) copper, with or without amendment with EDTA. The addition of EDTA to these substrates increased the solubility of the copper to levels that killed other metal‐tolerant species (Biscutella laevigata and Brassica juncea), but not E. andevalensis. The copper concentrations in wild plants were only 1 to 24 μg g‐1 (dry weight) despite the high levels of copper (up to 3,676 μg g‐1) in the supporting soils. In the pot trials, the plant was able partially to exclude total copper up to 1,000 μg g‐1 in the soil. Thereafter, there was an exponential increase of copper in plant until the limit of tolerance was reached. Conclusions of the study were: (a) tolerance to copper by t...

Unusual hyperaccumulation (>500 mu g/g dry mass) of toxic Tl has been determined in Iberis intermedia (Brassicaceae) from southern France. This species contained up to 3,070 mu g/g (0.31%) Tl in the whole-plant dry matter. Pot trails with Iberis showed that it could tolerate nearly 2,000 mu g/g available Tl in the substrate compared with about 20 mu g/g for the metal-tolerant grass Arrhenatherum elatius. This unusually high accumulation of Tl has significance for animal and human health, phytoremediation of contaminated soils, and phytomining for Tl. It was determined that three crops of Iberis would be sufficient to phytoremediate to a non-toxic level, a soil containing 10 mu g/g Tl, and the production of a saleable plant ash (bio-ore) would probably pay for the cost of the operation. Phytomining (growing a "crop" of a metal over ores subeconomic for conventional mining) could be a viable option since it has been calculated that a net return of $1,200/ha (twice the return from a crop of wheat) would be possible with a biomass yield of 10 t/ha containing 0.08 percent Tl in dry matter. The break-even point (net yield of $500/ha) would require 170 mu g/g (0.017%) Tl in dry matter. Such a project would, however, require a large area to be able to afford economies of scale.

Azimilide, a novel class III antiarrhythmic agent, blocks both the slowly activating (IKs) and rapidly activating (IKr) components of the delayed rectifier potassium current, which distinguishes it from conventional potassium channel blockers such as sotalol and dofetilide, which block only IKr. Azimilide is being developed to prolong the time to recurrence of atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia in patients with and without structural heart disease. Azimilide is also being studied for its role in prevention of sudden cardiac death in high-risk patients after myocardial infarction (MI). Preclinical and clinical studies indicate that azimilide prolongs cardiac refractory period in a dose-dependent manner, as manifested by increases in action potential duration, QTc interval, and effective refractory period. Azimilide does not affect PR or QRS interval and minimally affects hemodynamic properties such as blood pressure and heart rate. Its in vivo effects appear to be rate-independent and are maintained under ischemic or hypoxic conditions, properties of potential clinical significance. Azimilide has shown excellent efficacy (>85%) in suppressing supraventricular arrhythmias in a variety of dog models. It also suppressed complex ventricular arrhythmias in infarcted dogs and, in a sudden death cardiac model, decreased mortality. Azimilide pharmacokinetics are very predictable. The drug is completely absorbed, and the extent of absorption is not affected by food. It can be administered once daily. Clinical data suggest that dose adjustments of azimilide are not required for age, gender, hepatic or renal function, or concomitant use of digoxin or warfarin. Azimilide has a good safety profile in open-label safety studies in >800 supraventricular arrhythmia patients, most with structural heart disease. The incidence of serious adverse events, including torsade de pointes, is low. The rate of patient withdrawal from long-term studies is also encouragingly low. Unlike amiodarone, azimilide has shown no evidence of pulmonary or ocular toxicity. Azimilide is expected to provide a unique new therapy for the prevention of supraventricular arrhythmias and sudden cardiac death when Phase III clinical trials are complete and safety and efficacy are confirmed.

Uptake of Cd, Zn, Pb and Mn by the hyperaccumulator Thlaspi caerulescens was studied by pot trials in plant growth units and in populations of wild plants growing over Pb/Zn base-metal mine wastes at Les Malines in the south of France. The pot trials utilised metal-contaminated soils from Auby in the Lille area. Zinc and Cd concentrations in wild plants averaged 1.16% and 0.16% (dry weight) respectively. The unfertilised biomass of the plants was 2.6 t/ha. A single fertilised crop with the above metal content could remove 60 kg of Zn and 8.4 kg Cd per hectare. Experiments with pot-grown and wild plants showed that metal concentrations (dry weight basis) were up to 1% Zn (4% Zn in the soil) and just over 0.1% Cd (0.02% Cd in the soil). The metal content of the plants was correlated strongly with the plant-available fraction in the soils as measured by extraction with ammonium acetate and was inversely correlated with pH. Bioaccumulation coefficients (plant/soil metal concentration quotients) were in general higher for Cd than for Zn except at low metal concentrations in the soil. There was a tendency for these coefficients to increase with decreasing metal concentrations in the soil. It is proposed that phytoremediation using Thlaspi caerulescens would be entirely feasible for low levels of Cd where only a single crop would be needed to halve a Cd content of 10 μg/g in the soil. It will never be possible to remediate elevated Zn concentrations within an economic time frame (

Ultramafic (“serpentine”) soils from and adjacent to the Dun Mountain Ophiolitic Belt, South Island, New Zealand were analysed for 11 elements in order to establish to what degree edaphic factors influenced the character of the overlying vegetation. Using principal components analysis with a mutual plot of the first two principal components, involving the total elemental concentrations in the soils, it was possible to divide the soils into 6 virtually non-overlapping fields, each of which represented a specific vegetation community. Component 1 was essentially an “ultramafic plot” with heavy loadings from the elements chromium, cobalt, iron, magnesium, manganese, and nickel. Component 2 was a “non ultramafic” plot with heavy loadings from aluminium, copper and zinc. For elements extracted from the soils at pH 5.9, discrimination was somewhat poorer but confirmed the great importance of magnesium and nickel as controlling elements for the serpentine vegetation. It was concluded that the results indicated the overriding importance of edaphic factors in controlling the serpentine vegetation.

Ultramafic ("serpentine") soils from the Nelson Region contain low total levels of calcium, potassium, phosphate and high total levels of chromium, cobalt, iron, magnesium, manganese and nickel. However, the plant‐available fraction as measured by extraction procedures, differs considerably from the total elemental abundances in the soils.The solubility of individual elements is unrelated to total abundance in the soil. Only extractable manganese and iron could be predicted by their total concentration. Extraction experiments indicated that chromium and cobalt have low solubility in the pH range to which serpentine plants are exposed and therefore unlikely to be toxic. Soil analyses across a sedimentary/ultramafic soil boundary indicated that higher levels of extractable nickel and/or magnesium in ultramafic soils seem likely to account for the observed vegetation change. The pH of soils under beech forest was significantly lower than that under serpentine vegetation and was probably a result of humic dec...

An expedition to Southern Morocco was undertaken to study and collect the poorly documented metal-tolerant flora of the Bou Azzer region. The areas visited are underlain by ultramafic rocks with associated cobalt-nickel arsenide mineralization and chromium carbonates (Bou Azzer), and by volcano-sedimentary rocks with associated copper sulphide mineralization (Bleida). Biogeochemical studies were made of metals in many species, of which the five most common are Anvillea garcinii subsp. radiata, Ononis natrix (goat-root), Laiandula multifidia (lavender), Convolaulus trabutianus (morning-glory), and Artemisia herba-alba (sagebrush). Results show differences in the ability of each species to accumulate metals. Ononis concentrates most of the ore-forming elements to highest levels. However, because of its more widespread occurrence, Anuillea is a more appropriate sample medium for biogeochemical surveys. From chemical analysis of its stems, zones of concealed mineralization can be identified where conventional soil analysis is less definitive.

Mercury and arsenic levels were determined in the flesh and livers of rainbow trout (Oncorhyncus mykiss Richardson) and brown trout (Salmo trutta L.) from lakes of the Taupo Volcanic Zone, and some locations on, or near, the Waikato River, North Island, New Zealand. All the fish sampled had measurable amounts of mercury in their flesh. Some trout from Lakes Rotorua, Rotoiti, and Rotomahana and trout from the Puwheto stream had flesh mercury concentrations above the World Health Organization's limit for mercury in foodstuffs. There were significant positive correlations between the flesh mercury concentration and the body weight and/or length of the trout. Brown trout taken from Puwheto had higher flesh mercury concentrations than rainbow trout taken from the same area. This may have been because the brown trout had a greater average length. Arsenic concentrations in the flesh of all the trout were of the same order of magnitude as the water from which they were taken and therefore pose no threat t...

When fullerenes were first discovered to form spontaneously in condensing carbon vapors ( Kroto et al., 1985), it was suggested that they might be widely distributed in the Universe. Searches for fullerenes in meteorites (see Devries et al., 1993) were unsuccessful, but C 60 and C 70 were reported to occur on Earth in samples of shungite, a meta-anthracite from a deposit near Shunga, Russia ( Buseck et al., 1992), and in “fulgurite”, a substance formed when lightning strikes certain soils or rocks ( Daly et al., 1993). The occurrence of fullerenes in shungite is particularly surprising since fullerene synthesis in the laboratory has always involved gas phase chemistry at temperatures over 1000°C. Such conditions may be attained during lightning strikes, but shungite is believed to have formed from carbonaceous material creeping into fissures of a Precambrian rock which metamorphosed under extreme pressures. If the original carbonaceous material did not already contain fullerenes perhaps from wildfires, they must have formed during the metamorphism by as yet unknown solid- or liquid-phase mechanisms.

Sixteen trace elements (Al, As, Br, Cl, Co, Cr, Eu, Fe, La, Mn, Mo, Ni, Sb, Sc, V and W) were determined in 36 crude oils and condensates from New Zealand sedimentary basins, mostly from the Taranaki Basin. Concentrations of Al correlated strongly with “clay mineral” elements such as Cr, Fe, La, Mn, Mo and Sc. This indicated that most of the trace elements were bound in entrapped clay fractions. Although a Ni vs. V plot did not allow for effective discrimination of different oils and condensates because the number of Ni values (6) was so small, the abundances of both elements were extremely low and in the same range of values as Chinese non-marine oils. Principal components analysis of the data showed that two components (involving 15 elements) accounted for 66.9% of the variance of the system. A mutual plot of these two components indicated that the Maui-1 offshore oil and the Waiotapu and Kotuku seepage oils were separate from the main group of crudes from the Taranaki Basin.

— Thallium has been quantified in 50 iron meteorites and 6 chondrites using a combination of solvent extraction and graphite furnace atomic absorption spectrometry. The accuracy of the data was checked by analysis of two iron meteorites by laser-excited ICP mass spectrometry. The Tl abundance values for irons appear to be the first recorded and show that the Tl content allows for taxonomic separation of several groups on Tl vs. Ni abundance plots. The Tl content of irons is inversely correlated with abundances of platinum group metals such as Ir, Pt, and Rh and, in this respect, behaves like Pd and As that favour sulphur-rich phases in meteorites. Analysis of carbonaceous chondrites showed a 30-fold enrichment of Tl compared with ordinary chondrites.

Pd, Pt and Ru have been quantified in 117 iron meteorites by procedures involving a combination of extraction into organic solvents and analysis of the extracts by graphite furnace atomic absorption spectrometry. Our data for these three metals, particularly for Pd, have enabled us to assemble a sufficient largee pool of information from which to draw conclusions clusions concerning their taxonomic potential based on their distribution pattern in iron meteorites. Unlike Ru and Pt, the Pd concentrations give a positive slope when plotted against Ni contents and their mass abundance ratios are very close to the cosmic ratio. Pd and Ni are probably enriched in the later solid during fractionation. Distribution coefficients (solid/liquid concentration ratios) for Ir, Pt, Ru and Pd as determined from the Rayleigh equation are 4.0, 1.4, 1.1 and 0.8, respectively. This sequence is some measure of the usefulness of the elements for taxonomic classification of iron meteorites and is the same sequence as obtained elsewhere by statistical interpretation of abundance data. The positive correlation between the Pt and Ru abundances is extremely close and there is also a good negative correlation between concentrations of Pd and each of Pt and Ru. It is proposed that low-Ni IIICD meteorites belong more appropriately to group IAB since we have been unable to find intermediate values for Ru, Pd, or Pt linking the low-Ni and high-Ni subgroups of IIICD.

Two chemically similar nonsteroidal anti-inflammatory drugs, orpanoxin and F-1067, had almost identical potencies and efficacies as anti-inflammatory (rat paw edema) and analgesic (mouse writhing) agents, but differed markedly in gastrotoxicity. Orpanoxin alone aggravated stomach lesions in rats subjected to pylorus ligation and failed to protect stomachs of rats challenged with indomethacin. The compounds did not differ in their in vitro enzyme inhibition effects, both failing to inhibit 5- and 15-lipoxygenase and both inhibiting prostaglandin synthetase. Extraction of prostagiandins from the gastric mucosa of pylorus-ligated rats revealed, however, that the safer F-1067 depleted prostaglandin 6-keto-F1α less and increased prostaglandin E2 much more than did orpanoxin. A possible causality is suggested.

On the basis of compositional evidence from abundances of Ni and noble metals in iron meteorites, pairings of a number of meteorites were examined. It was concluded that: in group IIICD, Carlton is paired with Lamesa; in group IIB, “Onnum Valley” (DP88020) and “CM66” (DP88023) are paired with the Derrick Peak shower; in group IVA, Railway and “G2011” are paired with Gibeon; and in group IIIE, Paneth's Iron is paired with Coopertown rather than with Burlington or Staunton.

A procedure was developed for the quantification of thalium at the ultratrace level (ng g −1 in geological materials. The sample is dissolved in 3 M H 2 SO 4 to which is added KI and K 2 HPO 4 . The thallium is then extracted as its iodo complex into methylisobutyl ketone (MIBK), leaving behind most of the iron. The remainder of the iron is removed from the organic layer by back-extraction into 3 MH 2 SO 4 . The added K 2 HPO 4 enhances the extraction of thallium into the MIBK layer which is then analysed by graphite furnace atomic absorption spectrometry. The limit of detection (3σ) was about 2 ng g −1 in the original solid sample, though this could be reduced by further multiple loadings. Precision and accuracy were determined by analysis of the standard reference rocks G-1, W-1 and CAAS Sulphide Ore. The precision ranged from 3.03–10.5% depending on the thallium content of the rocks, and the relative error (accuracy) ranged from 2.1–6.7%.

Au, As, Ru, Pd, Rh, Os, Ir and Pt were quantified in 120 iron meteorites using graphite furnace atomic absorption spectrometry and instrumental neutron activation analysis. The data were combined with literature values for Ga, Ge and Ni in order to devise a statistical group classification system based on principal components and discriminant analyses, while at the same time preserving the integrity of the existing classification system as far as possible. If Ga and Ge are excluded, 72.9% of the total variance of the system was accounted for by abundances of Ir, Os, Pt and Ru. Very little of the variance was accounted for by Ni and Pd. If Ge and Ga are included, they become the most important diagnostic elements and the order of importance for group classification is then Ga > Ge > Ir > Os > Ru > Pt. The discriminant analysis of the abundance data involved use of the D 2 statistic, initially over all groups excluding anomalous irons. Where group changes were inferred, meteorites were transferred to their new groups and the calculations repeated. The next stage involved adding the anomalous irons to the pool of data to establish whether any of these could be assigned to a group. The final stage of classification involved examining the morphological and mineralogical properties of nine meteorites whose change of group had been inferred by the statistical procedures. On this basis, reassignment of four meteorites was rejected and the remaining five accepted. The latter included Cranbourne, Jaralito, Mundrabilla and Nantan, formerly low-Ni IIICD meteorites, that we now recommend should be returned to group IAB from which they had previously been removed. We also recommend that Denver City (formerly ungrouped) be reassigned to group IIIF Anom. Our statistical procedure confirms the validity of previous classifications not involving statistical discrimination.

A procedure was developed for the graphite furnace atomic absorption spectrometric determination of gallium in high-iron geological materials such as iron meteorites. To overcome sevre interference from iron, gallium is extracted as a chloro complex from 5 M hydrochloric acid into isobutyl methyl ketone. Iron is reduced by addition of potassium iodide and its co-extraction into the organic phase is thereby decreased to

The uptake of Ni, Co, and Cu by the nickel hyperaccumulator Alyssum troodii Boiss and the non-accumulator Aurinia saxatilis (L.) Desv. were studied in pot trials using artificial rooting media with varying concentrations of the metals added as soluble salts, singly and in combination. The ability of five other Ni hyperaccumulating species of Alyssum to hyperaccumulate Co was also investigated. Leaves and stems of A. troodii accumulated Ni to almost the same extent (8000–10 000 μg g-1). In roots, the highest Ni concentration was 2000 μg g-1. In leaves of Au. saxatilis, the maximum Ni concentration was only 380 μg g-1 and the level in roots was even lower. In media containing Co, the maximum concentration of this element in A. troodii (2325 μg g-1) was ten times higher than in the non-accumulator species. Slightly less Co was found in stems and roots of both species. Among the other Ni hyperaccumulators, the maximum concentration of Co in leaves ranged from about 1000–8000 μg g-1. Copper concentrations were the same in all organs of both species when they were grown in copper-rich media and were in the range 40–80 μg g-1, showing that neither plant was capable of taking up Cu at levels comparable to those of Ni and Co. When both plants were grown in media containing equal amounts of both Co and Ni, the Co concentrations in plant organs were the same as for specimens grown in media containing Co only. However, the Ni levels were lower in both species. Uptake of Co therefore appeared to suppress Ni uptake. Pot trials showed that the order of tolerance was Ni>Cu>Co for A. troodii and Ni>Co≈Cu for Au. saxatilis, whereas the seedling tests showed the order to be Co>Ni>Cu. At metal concentrations ≥10 000 μg g-1, the overall tolerance of A. troodii was greater than that of Au. saxatilis which exhibited equally low tolerance to Ni and Cu. We conclude that in A. troodii, A. corsicum Duby, A. heldreichii Hausskn., A. murale Waldstein & Kitaibel, A. pintodasilvae T.R. Dudley, and A. tenium Halacsy, Ni tolerance and hyperaccumulation conveys the same character towards Co. This behaviour should be investigated in other hyperaccumulators of Ni and/or Co.

A quantitative method for testing antiinflammatory agents in beagles has been developed, based on measurement of paw inflammation induced by a local injection of carrageenin. Carrageenin [0.5 mL of 2% (wt/vol) in saline] was injected into the plantar region of the hindpaws of pentobarbital-anesthetized beagles. Paw pressure changes registered from a water-filled balloon held on the top of the paw by a light adhesive tape wrapping were monitored for 240 min. In control dogs given 0.5% (wt/vol) methylcellulose (10 mL/kg orally) just before carrageenin, paw pressure increased significantly (p less than 0.05) over eightfold, from 2.9 +/- 0.8 mm Hg (mean +/- SEM, n = 29 paws) at 75 min to 26.0 +/- 3.5 mmHg at 240 min. The increase in paw pressure was significantly inhibited by the cyclooxygenase inhibitors, ibuprofen, indomethacin, and orpanoxin, and partially inhibited by the lipoxygenase inhibitor, phenidone, administered orally before carrageenin injection. Thus this model, with further characterization, could provide a convenient, quantitative way of assessing the efficacy of nonsteroidal antiinflammatory agents in dogs.

A procedure for determining vanadium in steels and geological materials involves dissolving the samples in concentrated HNO3 for steels and iron-rich meteorites or in HClO4-HF-HNO3 (1:1:1) for siliceous materials. The solutions are evaporated to dryness and the residue is dissolved in 6 M HCl. The solutions are oxidized with K2S2O8 and KMnO4 at 70°C prior to separation of iron, chromium and molybdenum by extraction into isobutyl methyl ketone. After separation, the aqueous solution is reoxidized with KMnO4 at 70°C. The residual solution containing vanadium and nickel is evaporated to dryness, the residue dissolved in 6 M HNO3 and the vanadium extracted into tributyl phosphate, leaving the nickel behind. This purified extract is back-extracted into 2% H2O2 in 6 M HNO3. The aqueous back-extract is analysed for vanadium by graphite furnace atomic absorption spectrometry. The limit of detection is about 0.3 μg V g−1 in the original sample. The relative standard deviation of the method was 3.7% for seventeen replicates of the NBS SRM 361 standard steel, with a relative error of 4.5%. Replicate analyses of standard silicate rocks (CAAS SY-1 anal SU-1) gave similar good precision and accuracy. Vanadium was determined in several iron meteorites and in the carbonaceous chondrite Allende.

Platelets from normal and malignant hyperthermia (MH)-susceptible pigs were evaluated for differences in 45 calcium uptake in the absence or presence of caffeine (2–16 mM), halothane (0.05–0.5%), or halothane and caffeine together. There were no statistically significant differences in basal or halothane-inhibited calcium uptake by platelets from either source. There was a small statistically significant difference in calcium uptake between platelets from normal and MH-susceptible pigs in the presence of 16 mM caffeine and 0.5% halothane. Calcium uptake by platelets from one pedigree of MH-susceptible pigs were stimulated in a concentration-dependent manner by caffeine. These data suggest that exposure of platelets to caffeine may have potential for identifying MH-susceptiblity.

Following the discovery of the hyperaccumulation of nickel by the Philippine plant Dichapetalum gelonioides subsp. tuberculatum , the nature of the nickel in aqueous plant extracts has been investigated by gel chromatography, ion exchange chromatography, high voltage electrophoresis and GC-MS. The purified extract contained 18% Ni, 24% citric acid and 43% malic acid(mole ratio 1:0.4:1), the remainder consisting of small amounts of Ca, Mg, K, Na and a trace of tartaric acid. Experimental observations are discussed in terms of the stabilities of complexes of citrate and malate with Ni. By using X-ray crystallography it was shown that crystals obtained from a Ni-citrate-malate solution simulating the extract, contain Ni exclusively in the form of an anionic Ni(II)-citrato complex.

A simple and inexpensive hydride generation atomic absorption spectrometric procedure was developed for the quantification of germanium in iron meteorites. The final procedure involved dissolving the meteorite in nitric acid, dilution with water, addition of citrate to buffer the solution and complex the iron and liberation of germanium hydride with sodium tetrahydroborate. The hydride was collected in a liquid air trap and fed into a nitrogen-hydrogen-air-entrained flame. The limit of detection (2σ) was 0.03 μg g−1 in the original meteorite and the r.s.d, was 3.9% for ten replicate analyses of the Toluca meteorite. The germanium content of this meteorite was 246 αg−1, the same as that obtained by neutron activation analyses (NAA). Analyses of nine iron meteorites afforded values in agreement with those previously obtained by NAA.

High-pressure liquid chromatography with ultraviolet-visible spectral analysis of toluene extracts of samples from two Cretaceous-Tertiary (K-T) boundary sites in New Zealand has revealed the presence of C(60) at concentrations of 0.1 to 0.2 parts per million of the associated soot. This technique verified also that fullerenes are produced in similar amounts in the soots of common flames under ambient atmospheric conditions. Therefore, the C(60) in the K-T boundary layer may have originated in the extensive wildfires that were associated with the cataclysmic impact event that terminated the Mezozoic era about 65 million years ago.

The ventricular proarrhythmic actions of five class III antiarrhythmic agents were compared in the Carlsson rabbit model. In adrenergically stimulated anesthetized rabbits, azimilide, clofilium, dofetilide, sematilide, and d,l-sotalol caused premature ventricular contractions and nonsustained and sustained ventricular tachyarrhythmias (NSVT and SVT) at pharmacologically equivalent intravenous doses that increased QTc intervals 20% (ED20). There were no significant differences between agents in the percentage of rabbits with serious arrhyhthmias at the ED20 doses of 5.2, 0.033, 0.015, 0.66, and 2.8 mg/kg i.v., respectively. Proarrhythmia was dose-dependent. Linear regression analysis of arrhythmia score versus log dose estimated the NSVT doses as 6.2, 0.055, 0.0089, 1.5, and 5.7, respectively. Analysis of arrhythmia states during a 10-min window after infusion when QTc prolongation was 20% showed that the compounds differed significantly in the proportion of time treated rabbits spent in SVT and combined NSVT and SVT. Rabbits treated with azimilide spent significantly less time in SVT and combined NSVT and SVT, followed in order of increasing time by d,l-sotalol, sematilide, clofilium, and dofetilide.

The technique of phytomining involves growing a crop of a metal-hyperaccumulating plant species, harvesting the biomass and burning it to produce a bio-ore. The first phytomining experiments were carried out in California using the Ni-hyperaccumulator Streptanthus polygaloides and it was found that a yield of 100 kg=ha of sulphur-free Ni could be produced. We have used the same technique to test the phytomining potential of the Ni-hyperaccumulators Alyssum bertolonii from Italy and Berkheya coddii from South Africa. The effect of different fertiliser treatments on growth of Alyssum bertolonii was established in situ in Tuscany and showed that the biomass of the plant could be increased by a factor of nearly 3 (4.5 t=ha to 12 t=ha) without significant loss of the Ni concentration (7600 mg=kg) in the plant. Analogous experiments have been carried out on Berkheya coddii where a biomass yield of over 20 t=ha can readily be achieved though the Ni concentration is not as high as in A. bertolonii. The total yield is, however, much greater. We have also been able to induce plants to hyperaccumulate Au by adding ammonium thiocyanate to the substrate. Up to 57 mg=kg Au (dry mass) could be accumulated by Indian mustard (Brassica juncea). Unusual hyperaccumulation (>500 mg=kg dry mass) of Tl has been determined in Iberis intermedia and Biscutella laevigata (Brassicaceae) from southern France. The Iberis contained up to 0.4% Tl (4000 mg=kg) in the whole-plant dry matter and the Biscutella over 1.5%. This unusually high accumulation of Tl has significance for animal and human health, phytoremediation of contaminated soils, and phytomining for Tl. We calculate that using Iberis, a net return of $ US 1200=ha (twice the return from a crop of wheat) would be possible with a biomass yield of 10 t=ha containing 0.08% Tl in dry matter. The break-even point (net yield of $ US 500=ha) would require 170 mg=kg (0.017%) Tl in dry matter. A model of a phytomining operation and its economics is presented and its advantages and disadvantages discussed. © 1999 Elsevier Science B.V. All rights reserved.

Vegetation and soil sampling were carried out in 80 plots located in five different ultramafic (serpentine) sites of Tuscany, central Italy. The physical and chemical features of each plot were determined and the species composition and cover recorded. The exchangeable fraction of soil metals was analysed because it gives a measure of their concentrations available to plants. The plots were classified by cluster analysis and ANOVA was used to compare the environmental variables of the groups of plots. Canonical correspondence analysis was used to detect the principal factors for gradients of species composition within the plant communities. A higher content of exchangeable metals was found under the more evolved and structured plant communities, suggesting that serpentine vegetation of Tuscany is not strongly limited by soil metals, such as chromium, cobalt, nickel and magnesium, typically associated with ultramafic soils. The low nutrient content of the soils and drought stress mainly due to topographical features, appear to have a more significant role in determining the typical scattered vegetation of the Tuscan ultramafics.

The class III antiarrhythmics azimilide dihydrochloride and dl-sotalol were evaluated for ability to suppress induction of ventricular tachyarrhythmias (VT) in anesthetized, male mongrel dogs 4-6 days after surgical infarction of the left ventricle (LV) produced by ligation/reperfusion of the left anterior descending coronary artery. Postmortem infarcts averaged 28.2 +/- 3.3% and 27.5 +/- 3.9% of the LV for azimilide- and sotalol-treated dogs, respectively. Both agents (0.3-30 mg/kg i.v.) increased ventricular effective refractory period as a function of dose in LV normal and infarcted zones without increasing conduction time. Azimilide was well tolerated hemodynamically up to 30 mg/kg i.v., whereas sotalol produced a significant and dose-related decrease in both blood pressure and heart rate. Azimilide was effective in five (56%) of nine dogs in preventing induction of ventricular arrhythmias by programmed electrical stimulation (PES) at doses from 1 to 30 mg/kg. Efficacy was seen for nonsustained and sustained VT and for ventricular fibrillation. Although sotalol (0.3-10 mg/kg) was effective in all five VT dogs tested, one of two nonsustained ventricular tachyarrhythmia (NSVT) dogs and two of three sustained ventricular tachyarrhythmia (SVT) dogs were reinducible with the baseline arrhythmia at doses higher than the effective dose, and one dog died after 30 mg/kg of sotalol. Both agents increased the cycle length of VT. Thus azimilide simultaneously increased refractoriness and provided antiarrhythmic efficacy as suppression of PES-induced ventricular arrhythmias in infarcted dogs without the hemodynamic depression seen with sotalol.

Azimilide and Atrial Flutter. Introduction: The effects of a Class III agent, azimilide di-hydrochloride, on atrial flutter circuits were studied in a functional model of single loop reentrant atrial flutter using dogs, 3 to 5 days after production of sterile pericarditis. Methods and Results: A computerized mapping system was used to construct activation maps from 138 to 222 epicardial sites in the right atrium. Doses of 3, 10, and 30 mg/kg IV azimilide dihydrochloride were analyzed in 8 dogs in which sustained atrial flutter lasting more than 30 minutes was induced by burst pacing. Atrial flutter was always due to a single loop circus movement reentry in the lower right atrium. At 3 mg/kg, azimilide dihydrochloride terminated atrial flutter in 2 dogs; however, atrial flutter was reinduced. At 10 mg/kg, atrial flutter was terminated in all 8 dogs but was reinduced in 4 dogs with slower rate. At 30 mg/kg, atrial flutter was terminated in the remaining 4 dogs and could not be reinduced. Atrial flutter cycle length always increased prior to termination. Isochronal activation maps showed that the increase in cycle length was due to additional conduction delays in the slow zone of the reentrant circuit. The site of termination was always located within the slow conduction zone situated in the lower right atrium between the line of functional conduction block and the AV ring. effective refractory periods (ERPs) were measured at selected sites in the slow zone and normal zone at twice diastolic threshold for the 10 mg/kg dose. Azimilide preferentially prolonged ERP in the slow zone (42.4 ± 20.l msec, mean ± SD) compared with (he normal zone (23.3 ± 15.4 msec, P < 0.0001). The increase in cycle length corresponded with the increase in ERP in the slow zone. Conclusions: In a functional model of circus movement atrial flutter, azimilide dihydrochloride terminates and prevents reinduction of atrial flutter by a preferential increase in refractoriness leading to further conduction delay and conduction block in the slow zone of the functional reentrant circuit.

Azimilide exhibited antiarrhythmic activity in several rodent models of ventricular arrhythmias. In the mouse chloroform model, azimilide provided limited efficacy by the i.p. route (50% at 100 mg/kg versus 20% by vehicle), and no efficacy by the oral route (300 mg/kg). In a rat model in which arrhythmias are induced by ligation and reperfusion of the left descending coronary artery (CALR model), azimilide provided dose-dependent (1-18 mg/kg) efficacy by the intravenous route. The estimated dose that suppressed ventricular fibrillation (VF) was 5.0 mg/kg i.v. At 18 mg/kg i.v. azimilide also partially suppressed ventricular tachyarrhythmia (VT) and extrasystoles (VES). Rats dosed orally (100 mg/kg) were fully protected from VF. In isolated guinea pig hearts exposed to 1 microM ouabain, azimilide at 10 microM prevented the VT and VF seen in 69% and 23%, respectively, of control hearts. In anesthetized guinea pigs, azimilide at 10 and 30 mg/kg i.v. increased the dose of ouabain required to induce VES. While sematilide, dofetilide, and E-4031 significantly increased sensitivity to the arrhythmogenic actions of ouabain (by lowering the dose that caused VF), azimilide did not. Azimilide's antiarrhythmic profile in these rodent models differs from that of other class III agents, since azimilide had less efficacy in the mouse chloroform model, could suppress VT and VES as well as VF in the CALR rat model, and protected from or did not aggravate cardiac glycoside-induced arrhythmias in guinea pigs. These results demonstrating the antiarrhythmic efficacy of azimilide in the intact animal suggest that the compound has a different profile than other class III agents.

The in vivo characterisation of ZM 241385 (4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-+ ++ylamino] ethyl)phenol), a novel, non-xanthine, selective adenosine A2A antagonist is described. In anaesthetised dogs ZM 241385 (i.v.) was 140-fold more potent in attenuating vasodilator responses to exogenous adenosine in the constant flow perfused hind limb than the bradycardic effects. In pithed rats in which blood pressure was supported by angiotensin II infusion, ZM 241385 (10 mg kg-1, i.v.) did not inhibit the hypotensive or bradycardic effects of the A3/A1 receptor agonist N(6)-2-(4-amino-3-iodophenyl)ethyladenosine (APNEA). In conscious spontaneously hypertensive rats, ZM 241385 (3-10 mg kg-1, p.o.) selectively attenuated the mean arterial blood pressure response produced by exogenous adenosine. No inhibition of the bradycardic effects of adenosine was observed following these doses of ZM 241385. The results indicate that ZM 241385 can be used to evaluate the role of adenosine A2A receptors in the action of adenosine in vivo.

The potential cytoprotective effect of the purine transport inhibitor S-(p-nitrobenzyl)-6-thioinosine (NBTI) in a model of myocardial ischaemia and reperfusion was investigated in the anaesthetised ferret. The left anterior descending coronary artery (LAD) was occluded for 90 min, producing ischaemia in 53 +/- 3% of the left ventricular free wall, followed by 240 min reperfusion. NBTI (0.5 mg kg-1, i.v.) was given prior to ischaemia or prior to reperfusion. In addition the effect of purine transport inhibition was investigated in animals subjected to ischaemia without reperfusion. NBTI reduced infarct size from 84.0 +/- 1.7 to 71.4 +/- 3.7% of the area at risk (P0.05) when given prior to occlusion of the LAD. NBTI was ineffective however when given 15 min prior to reperfusion. NBTI had no effect upon infarct size produced by ischaemia without reperfusion. The effect of NBTI was independent of significant changes in myocardial blood flow during ischaemia and reperfusion or upon neutrophil infiltration.

Selectivity of captopril, enalapril (MK-421), enalaprilat (MK-422), ketoace, and SA-300 for inhibiting kininase II when angiotensin (ANG) I versus bradykinin (BK) is the substrate has been studied in vitro. Potency for inhibiting purified rabbit lung ANG I-converting enzyme (ACE) using a tripeptide substrate with an ANG I-like (hippurylhistidylleucine, HHL) or a BK-like (hippurylphenylalanylarginine, HPA) cleavable dipeptide was determined. Inhibition of ANG I-induced and potentiation of BK-induced contractions of isolated guinea pig ileum strips was measured. For the enzyme assay, the inhibitor concentration which reduced the rate of HHL and HPA hydrolysis 50% (IC50) from the control value was estimated. All tested compounds more potently inhibited hydrolysis of the ANG I-related tripeptide by the purified enzyme. Ketoace, with a selectivity ratio (HPA IC50:HHL IC50) of 23, was the most substrate-dependent inhibitor. For the isolated ileum assay, the inhibitor concentration which augmented the contractile response to BK by 50% (AC50) or inhibited the contractile response to ANG I by 50% (IC50) was calculated. Only enalaprilat retained a selectivity ratio (BK AC50:ANG I IC50) in the guinea pig ileum system greater than one. Ketoace, with a ratio of 0.038, was the least ANG I-selective by this criterion. In vivo selectivity data on captopril seem more in accord with the ileum, rather than the enzyme, results. It was concluded that converting enzyme inhibitors differ in their relative selectivity for inhibiting kininase II reactions using different substrates.