Effects of salsolinol on cultivated endothelial cells

In view of neurotoxic properties of tetrahydroisoquinolines (TIQ's) there are open questions also in regard to the disturbance of the blood-brain barrier. Because endothelial cells are an important element of this barrier the present study was designed to assess the influence of salsolinol (a TIQ formed by condensation of dopamine and acetaldehyde) on cultivated endothelial cells by physiological, biochemical and morphological investigations. For the investigations we used aortic endothelial cells because of a variety of similarities in physiology and biochemistry to brain capillary endothelial cells. Cytotoxic effects estimated by cell counting after 72 h treatment with salsolinol (IC₅₀=38 mol/l) were possibly caused by mitochondrial damages. Already after 2 h severe ultrastructural alterations of many mitochondria could be observed. The respiration activity of the cells was always inhibited after treatment with salsolinol for some hours. The damage of the mitochondria by salsolinol was not connected with inhibition of the activity of succinate dehydrogenase and cytochrome c+c₁. Nevertheless the damages of mitochondrial integrity support the hypothesis that the neurotoxic effect of salsolinol is primarily caused by damaging the endothelial cells associated with a disturbance of blood-brain barrier.     

Effects of a pregrowth period in Al-free nutrient solution on macronutrient composition of two upland rice cultivars with various Al sensitivity

Effects of Al on growth and macronutrient distribution (K. P. Ca and Mg) were examined in two rice ( Oryza sativa L.) cultivars (BG35 and IR45) pregrown in a nutrient solution without Al for 21 days followed by 14 days at 0.70. 140 or 280 μ M Al (pH 4.2 ± 0.1). Relative growth rate (RGR) of pregrown plants was significantly less hampered by Al compared to their controls, than RGR of plants that were not pregrown. However, a similar ranking of the cultivars for Al sensitivity was obtained irrespective of pregrowth period. The more Al tolerant BG35 consistently outyielded the Al sensitive IR45 under all Al treatments. A comparatively high Al-retention in roots and low Al transport rate to shoots of pregrown IR45 was the opposite of conditions in non-pregrown IR45. In BG35, uptake and transport of nutrients to the shoots were efficient at all Al levels. In IR45, particularly the uptake and distribution of P and Mg were disturbed by Al. It is suggested that a pregrowth or nursery period without Al reduces Al toxicity in both BG35 and IR45 at least up to 280 μ M Al.     

Consistency and sensitivity of community level endpoints in microcosm tests

We review microcosm toxicity tests with 12 chemical stresses and find that the relative sensitivity of certain endpoints is consistent over toxicant type. Changes in species composition occur at very low levels of chronic stress. Endpoints responding at increasing levels of stress are declines in species numbers relative to expected numbers, followed by decreased oxygen production and decreased total production. Other endpoints are quite sensitive in response to some toxicants but insensitive to others (e.g., autotrophic biomass). In addition, other endpoints respond unpredictably to stress, showing stimulation under some conditions and impairment under others. We compare our observations to the progressions of impact suggested from published whole ecosystem experiments and speculate about a general ecosystem distress syndrome and the implications for choosing endpoints in both toxicity testing and monitoring.     

Effects of natural sediment properties on test results in bioassays with oyster larvae (Crassostrea gigas) on sediment elutriates

Toxicity tests with oyster larvae are becoming increasingly important as sensitive bioassays for assessing water and sediment quality. In 1983 a procedure was presented specifically for the testing of seawater elutriates of sediment samples. Testing sediment elutriates with oyster larvae in a sediment-water system invokes specific problems related to natural sediment characteristics. Experiments were set up to study the effects of these sediment properties on the bioassay results. The effects of sediment grain size, suspended solids, elutriation period, as well as the possible effects of naturally occurring toxic nutrients, like ammonia, were studied. Also the effect of presence or absence of the elutriated sediment and the distribution of larvae in the test vessels were studied.It is concluded that natural sediment properties can have substantial effects on the test results in elutriate tests with sediment present in the test vessel. Recommendations are formulated to minimize these effects or to use other test fractions for predicting bulk sediment toxicity.     

COEXLSTENCE OF TOXIC AND NONTOXIC DINOKLAGELLAIES RESEMBLING GQNYAULAX TAMARENSIS IN NEW ENCILAND COASTAL WATERS (NW ATLANTIC)1

Two forms resembling Gonyaulax tamarrensis Lebour coexist in Maine cosat plankton; one is toxic, the other is nontoxic. At times, red patches of dinoflagellates were identified as G. tamarensis, yet only presumed to he toxic. Toxic froms were found in June, July 1975 and 1976. The nontoxic form was found in a more esraurine area, e.g., mid-July 1975, early July 1976. These two forms are not easily distinguished by conventional microncopic ohservation, nor by pigment analysis. Preliminary observations suggest that the nontoxic form is smaller than G. excavata (Braarud) Balech and tacks the “excavated” ventrat region. Characteristic G. excavata resting cysts were found in sediment from the shellfish toxic area off Newagen and Monhegan (Maine) and were not found in sediments from areas where the nontoxic form bloomed. There appear to be a minimum of two G. tamarensis-like organisms. Full systematic treatment of these must await further information.     

Toxicity of carbaryl and 1-naphthol to four species of freshwater fish

The toxicity of the carbamate insecticide carbaryl (Seven√) and its metabolite, 1-naphthol, to four species of fish was studied. The calculated 96 h LC 60 values of carbaryl forCatla catla (Ham.), Anabas testudineus (Bloch),Mystus cavasius (Ham.) andMystus vittatus (Bloch) are 6.4, 6.6, 4.6 and 2.4 ppm respectively and that of 1-naphthol are 4.3,3, 0.33 and 1.1 ppm respectively. The degradation product of the insecticide was found to be more toxic than the parent compound, to all the four species studied.     

Protein a of quinolinate synthetase is the site of oxygen poisoning of pyridine nucleotide coenzyme synthesis in Escherichia coli

De novo biosynthesis of pyridine nucleotide coenzymes in Escherichia coli is initiated by an enzyme complex (quinolinate synthetase) containing protein B which converts l-aspartate into iminoaspartate protein A, which then generates quinolinate on the pathway to the coenzymes. This complex has been shown to be poisoned by hyperbaric oxygen. ^7,8 We performed assays made dependent on both proteins B and A versus only protein A, using cell-free extracts of hyperbaric-oxygen poisoned and aerobically grown cells. The specific activities were produced by a similar amounts of 68% and 60%, respectively, when measured in assays made dependent on enzymes B and A versus only protein A that was derived from oxygen-poisoned extract. Thus, protein A is the oxygen-sensitive component.     

Individual and combined toxicity of three heavy metals,Cu, Cd and Cr for the marine copepod Tisbe holothuriae

The acute toxicity of Cu, Cd and Cr to the marine copepod Tisbe holothuriae, Humes, was estimated by static bioassays and the LC _inf50 ^su48h (in mg/l) was calculated. Copper proved to be the most toxic (LC _inf50 ^su48h = 0,08 ± 0,01 mg/l) and chromium the least toxic (LC _inf50 ^su48h = 8,14 ± 0,05 mg/l), while cadmium showed an intermediate toxicity (LC _inf50 ^su48h = 0,97 ± 0,04 mg/l).In mixtures of the two metals an obvious synergism of the effects was observed in all cases. In all three combinations with two metals (Cu + Cd, Cu + Cr, and Cd + Cr) the mortality was higher than that expected on a purely additive basis. The mixture of the three metals presented a higher toxicity than that of the individual metals acting separately, but lower than that of all two metals mixture.     

Chronic Manganese Treatment of Rats Alters Synaptosomal Uptake of Dopamine and the Behavioural Response to Amphetamine Administration

Abstract: Chronic manganese treatment from conception onward resulted in increased striatal synaptosomal uptake of dopamine, but not of a variety of other neurotransmitters/precursors in 80-day-old rats. The open-field behaviour of these manganese-treated 80-day-old rats was no different from that of untreated age-matched rats. However, amphetamine administration (1 mg/kg body weight) increased activity to a significantly lower extent in manganese-treated rats. These observations indicate that chronic manganese treatment results in marked alterations of activities associated with the dopaminergic system.     

Interactions of radiofrequency radiation-induced hyperthermia and 2-methoxyethanol teratogenicity in rats

Radiofrequency (RF) radiation is used in a variety of workplaces. In addition to RF radiation, many workers are concurrently exposed to numerous chemicals; exposed workers include those involved with the microelectronics industry, plastic sealers, and electrosurgical units. The developmental toxicity of RF radiation is associated with the degree and duration of hyperthermia induced by the exposure. Previous animal research indicates that hyperthermia induced by an elevation in ambient temperature can potentiate the toxicity and teratogenicity of some chemical agents. We previously demonstrated that combined exposure to RF radiation (10 MHz) and the industrial solvent, 2-methoxyethanol (2ME), produces enhanced teratogenicity in rats. The purpose of the present research is to determine the effects of varying the degree and duration of hyperthermia induced by RF radiation (sufficient to maintain colonic temperatures at control [38.5], 39.0, 40.0, or 41.0 °C for up to 6 h) and 2ME (100 mg/kg) administered on gestation day 13 of rats. Focusing on characterizing the dose-response pattern of interactions, this research seeks to determine the lowest interactive effect level. Day 20 fetuses were examined for external and skeletal malformations. The results are consistent with previous observations. Significant interactions were observed between 2ME and RF radiation sufficient to maintain colonic temperatures at 41 °C for 1 h, but no consistent interactions were seen at lower temperatures even with longer durations. These data indicate that combined exposure effects should be considered when developing both RF radiation and chemical exposure guidelines and intervention strategies. Bioelectromagnetics 18:349–359, 1997. © 1997 Wiley-Liss, Inc.