Hair and bone as predictors of tissular mercury concentration in the western Alaska red fox, Vulpes vulpes.

We evaluated if total mercury (THg) concentrations of keratin-based and bone-based tissues can predict THg concentrations in skeletal muscle, renal medulla, renal cortex, and liver. The THg concentration in matched tissues of 65 red foxes, Vulpes vulpes, from western Alaska was determined. Hair THg concentration had a significant positive correlation with liver, renal medulla, renal cortex, and muscle. The THg concentration for males and females is moderately predictive of THg concentration in the renal cortex and liver for these foxes based on R(2) values (R(2)=0.61 and 0.63, respectively). Bone is weakly predictive of THg concentration in muscle (R(2)=0.40), but not a reliable tissue to predict THg concentration in liver (R(2)=0.24), renal cortex (R(2)=0.35), or renal medulla (R(2)=0.25). These results confirm the potential use of trapped animals, specifically foxes, as useful Arctic sentinel species to inform researchers about patterns in THg levels over time as industrialization of the Arctic continues.

Natural exposure of coastal river otters to mercury: relation to age, diet, and survival.

We evaluated effects of location (i.e., Jackpot Bay, a naturally contaminated site, and Herring Bay, reference site), diet as determined by stable isotopes, and age on mercury concentrations in individual river otters (Lontra canadensis) from Prince William Sound, Alaska, USA. We also investigated the effects of mercury accumulation on survival of river otters from these two locations. Our results indicated that mercury concentrations in fishes from Jackpot Bay were significantly higher than those in fishes from Herring Bay and those in pelagic fishes. In addition, a predominant intertidal fish diet in both areas influenced the accumulation of mercury concentrations in otters. Concentrations of mercury in fur of river otters from Jackpot Bay were significantly higher than those of animals from Herring Bay. Nonetheless, we did not detect significant differences in survival between otters inhabiting the two areas, suggesting that this natural contamination was not high enough to impair survival. Our ability to investigate the effects of various factors such as location, diet composition, and age on mercury accumulation and subsequent survival of individuals offers an example for a link between individual-based captive studies and population-level field investigations.

Biomarker responses in river otters experimentally exposed to oil contamination.

Investigations in Prince William Sound (Alaska, USA) following the Exxon Valdez oil spill (EVOS) revealed that river otters (Lontra canadensis) on oiled shores had lower body mass and elevated values of biomarkers, than did otters living on nonoiled shores. In addition, otters from oiled areas selected different habitats, had larger home ranges, and less diverse diets than animals living in nonoiled areas. These differences between river otters from oiled shores and those from nonoiled areas strongly suggested that oil contamination had an effect on physiological and behavioral responses of otters. In this study, we explored the effects of crude oil contamination on river otters experimentally. We hypothesized that exposure to oil would result in elevated values of biomarkers, indicating induced physiological stress. Fifteen wild-caught male river otters were exposed to two levels of weathered crude oil (i.e., control, 5 ppm/day/kg body mass, and 50 ppm/day/kg body mass) under controlled conditions in captivity at the Alaska Sealife Center in Seward (Alaska, USA). Responses of captive river otters to oil ingestion provided mixed results in relation to our hypotheses. Although hemoglobin (Hb, and associated red blood cells) and white blood cells, and possibly interleukin-6 immunoreactive responded in the expected manner, other parameters did not. Aspartate aminotransferase, alanine aminotransferase, and haptoglobin (Hp), did not increase in response to oiling or decreased during rehabilitation. Conversely, principle-component analysis identified values of alkaline phosphatase as responding to oil ingestion in river otters. Our results suggested that opposing processes were concurring in the oiled otters. Elevated production of Hp in response to tissue damage by hydrocarbons likely occurred at the same time with increased removal of Hp-Hb complex from the serum, producing an undetermined pattern in the secretion of Hp. Thus, the use of individual biomarkers as indicators of exposure to pollutants may lead to erroneous conclusions because interactions in vivo can be complicated and act in opposite directions. Additionally, the biomarkers used in investigating effects of oiling on live animals usually are related to the heme molecule. Because of the opposing processes that may occur within an animal, data from a suite of heme-related biomarkers may produce results that are difficult to interpret. Therefore, we advocate the exploration and development of other biomarkers that will be independent from the heme cycle and provide additional information to the effect of oiling on live mammals.

Melatonin acts as antioxidant and pro-oxidant in an organotypic slice culture model of Alzheimer's disease.

An organotypic mouse brain slice culture system of Alzheimer's disease (AD) under low oxygen partial pressures was developed to determine the antioxidant properties of the pineal hormone melatonin in vitro. Assays for biochemical markers of oxidative stress including redox active iron assay, heme-oxygenase-1 and 8-hydroxyguanosine inmunoreactivity were performed along with morphological analysis for stressed tissue following amyloid-beta (A beta) 1-40 insult. Melatonin (100 microM) significantly reduced the appearance of condensed chromatin, redox active iron, heme-oxygenase-1 induction and 8-hydroxyguanosine immunoreactivity caused by 50 microM A beta. Melatonin also prevented A beta-induced morphological signs of oxidative stress in tissue ultrastructure, including edema and dark degenerating profiles as visualized under electron microscope. At elevated concentrations (1 mM), melatonin induced redox active iron and heme-oxgenase-1 immunoreactivity. Thus, while melatonin may be a potential therapeutic agent in the prevention of oxidative stress associated with A beta and AD, it can also induce markers of oxidative stress at millimolar concentrations.

Response of river otters to experimental exposure of weathered crude oil: fecal porphyrin profiles.

Profiles of porphyrins were characterized in fecal samples from river otters (Lontra canadensis) experimentally exposed to weathered crude oil to determine effects on heme synthesis. Fifteen male river otters were randomly assigned to three groups of five individuals each representing a control group, a low-dosage group that received 5 mg/kg body mass of oil per day, and a high-dosage group that received 50 mg/kg body mass of oil per day. Mean levels of coproporphyrin III (CoproIII) and protoporphyrin IX (ProtoIX) in fecal samples collected from all experimental river otters were higher throughout the experimental period than levels of CoproIII and ProtoIX in fecal samples collected previously at two field sites. No statistically significant differences in levels of CoproIII and ProtoIX were observed between treatment groups, although a trend of reduction in variability in CoproIII was observed in the low- and high-dose groups. We found no relation between levels of CoproIII and ProtoIX, suggesting that the process of disruption that leads to oxidation of the precursors of porphyrins is probably nonlinear. Our results also indicate that the interaction between oiled induced reduction in hemoglobin levels and induction of CYP1A1 corresponded with significantly lower levels of ProtoIX in the fecal samples, possibly representing high demand for ProtoIX. Therefore, while this experiment does not support the use of porphyrin profiles as an individual biomarker, it does suggest that the latter may be valuable when a weight of evidence is used in an ecotoxicological risk assessment in which the interactions between several biomarkers are explored.

Toxicity assessment of total dissolved solids in effluent of Alaskan mines using 22-h chronic Microtox and Selenastrum capricornutum assays.

In order to overcome limitations associated with the Daphnia assay, we have explored two alternative assays, the 22-h chronic Microtox test and the 3-day S. capricornutum test, as substitutes. During this study, we compared the two assays using both a simple TDS standard solution and field water samples from two Alaskan mines. Using EC20 values, our results suggest that simple TDS standard solutions are not representative of environmental water samples of equivalent TDS concentrations. When comparing assays, our results showed that the 22-h Microtox assay was more reproducible and sensitive to effluent waters than the algal assay. Principle component analysis indicated that the 22-h Microtox test was generally more sensitive to nickel, ammonia and chloride while the S. capricornutum growth test appeared sensitive to cadmium levels.

Melatonin reduces interleukin secretion in amyloid-beta stressed mouse brain slices.

Neurodegeneration in Alzheimer's disease (AD) is associated with many features of the immune system. For example, cytokines such as IL-6, synthesized by microglia and astrocytes, are associated with senile plaques. To further study the role of cytokines in early stage AD neurodegeneration, an organotypic mouse brain slice culture system with microglia and astrocytes was developed. Amyloid-beta(Abeta1-40) induced the secretion of both IL-1beta and IL-6. Melatonin, an antioxidant and pineal hormone, reduced interleukin secretion in a concentration dependent manner. We also observed that melatonin, alone, had no effect on IL-1beta secretion but at a concentration of 500 microM induced the secretion of IL-6. This organotypic slice system can be used to study the early role of immune system molecules on neurodegeneration.

Comparison of spectrofluorometric and HPLC methods for the characterization of fecal porphyrins in river otters.

A spectrofluorometric method (B. Grandchamp et al., 1980, Biochem. Biophys. Acta 629, 577-586) developed for the determination of amounts of uroporphyrin I (Uro I), coproporphyrin III (Copro III), and protoporphyrin IX (Proto IX) in skin fibroblasts was compared with a high-performance liquid chromatography (HPLC) method for the analysis of porphyrins in fecal samples of river otters (Lutra canadensis). Heptacarboxylate porphyrin I and coproporphyrin I, two porphyrins determined to be critical in defining the porphyrin profile in fecal samples of river otters with the HPLC method, contributed substantially to the calculation of the concentrations of Uro I and Copro III, respectively, in standard solutions of porphyrins with the spectrofluorometric method. Fluorescent components of the fecal matrix complicated the determination of the concentrations of Uro I, Copro III, and Proto IX with the spectrofluorometric method and resulted in erroneous values for the concentrations of these porphyrins compared with values determined with the HPLC method. These results indicate that the complexity of the sample, particularly with regard to the potential presence of interfering fluorescent compounds, as well as porphyrins additional to Uro I, Copro III, and Proto IX, should be considered prior to the application of the spectrofluorometric method. An alternative HPLC method developed for the rapid characterization of porphyrin profiles in fecal samples of river otters is described.

Use of biomarkers in an indoor air study: lack of correlation between aromatic VOCs with respective urinary biomarkers.

The benzene and toluene levels inside of eight homes with attached garages were measured during July 1998 in Fairbanks, Alaska. A thermal desorption tube method and charcoal tube method were used to collect and analyze samples (thermal desorption tube method %RDS = 1.9 for n = 6; charcoal tube method %RDS = 6.5 for n = 4). Results for both methods were compared and showed indoor benzene levels ranging between 1.2 and 72 ppbv. The charcoal tube method usually gave lower results than the thermal desorption method. Nevertheless, the difference observed in benzene levels from each method was not significant as determined by application of the Wilcoxon t-test to these data. Using the thermal desorption method, the range of toluene found in homes was 0.1-111 ppbv. A correlation between toluene and benzene levels suggested the same point source. The benzene and toluene content of the indoor air and the number of small engines stored in the attached garage was also correlated. There was no correlation found between the urinary biomarker concentrations and the level of benzene or toluene measured inside the homes in the summer.

An ultrastructural analysis of tissue surrounding a microdialysis probe.

Microdialysis is a widely used in vivo sampling technique commonly used to monitor extracellular levels of a variety of molecules including neurotransmitters and metabolites. To facilitate interpretation of microdialysis results, this study critically examines changes in synaptic morphology induced by microdialysis. Tissue surrounding microdialysis probes was examined using light and electron microscopy at three distances from the probe tract. Microdialysis probes were implanted into rat striatum, and after 40 h of post-operative recovery were perfused with a modified Ringer's solution. Light microscope analysis revealed tissue disruption up to 1.4 mm from the probe site. Axonal damage indicative of non-excitotoxic insult was also seen as far away from the probe as was examined. The presence of dark-degenerating neurons was also noted and estimates of neuronal densities revealed loss up to 400 microm from the probe tract. This study, the first qualitative ultrastructural investigation of neuropil surrounding the probe site, indicated swollen processes up to 1.4 mm from the probe tract. Swollen mitochondria and bloated endoplasmic reticulum suggest intracellular chemical disruption. Tissue damage resulting in synaptic and neuronal disruption may affect neurotransmitter efflux or extracellular concentrations of metabolites.

Baseline levels of Hsp 70, a stress protein and biomarker, in halibut from the Cook Inlet region of Alaska.

The levels of Hsp 70, a heat shock protein, was quantitatively determined in Pacific halibut, Hippoglossus stenolepis, from the Cook Inlet region in south central Alaska. A dot blot analysis using a monoclonal antibody for Hsp 70 was combined with a standard protein analysis to determine Hsp 70 levels in 26 samples from gills. The average Hsp 70 concentration was 4.6 micrograms/mg, with levels ranging from 2.2 to 14.5 micrograms/mg total protein. Mercury in gill tissue also was measured and, in the 26 samples, only three samples had concentrations of mercury (X = 0.10 mg/kg, range = 0.09-0.11) above the minimum detection level.

Comparative baseline levels of mercury, Hsp 70 and Hsp 60 in subsistence fish from the Yukon-Kuskokwim delta region of Alaska.

In subsistence fish; northern pike (Esox lucius), burbot (Lota lota), whitefish (Coregonus nelsoni), grayling (Thymallus arcticus) and sheefish (Stenodus lencichthys), we determined the Hsp 60 and Hsp 70 levels in 31 samples from adult fish gills. A dot-blot analysis using antibodies to either Hsp 70 or Hsp 60 showed the average Hsp 70 concentration was 9.1 microg/mg protein, while the average Hsp 60 concentration was 147.4 microg/mg protein. Mercury levels in muscle tissue in these fish averaged 0.382 ppm. Using a subset of samples (n = 24), we determined that the major component in the muscle of Alaskan subsistence fish was methyl mercury. No correlation was observed between Hsp 60 or Hsp 70 expression in gill tissue and mercury concentrations in muscle tissue. Hsp 60 and Hsp 70 protein levels in the gills were correlated.

Expression of Hsp60, a stress protein, in human nasal septa cells after exposure to MTBE.

Human nasal septa epithelial cells (HNS) were exposed to low concentrations of methyl tert-butyl ether (MTBE). After an exposure of 24 h, the concentrations of heat shock proteins (Hsp) were determined after separation by gel electrophoresis and quantified with standardized Western blotting using densitometric imaging after background corrections. HNS cells showed an increase expression of the 60 kD molecular weight stress protein. The more commonly measured 70 kD Hsp appears to not increase in concentration after exposure to MTBE. This study revealed different expression patterns of Hsp to MTBE in nasal cells and showed that this applied technique might serve as a versatile screening tool to identify relevant environmental toxicants to nasal tissue.

Regional health assessment relating to mercury content of fish caught in the Yukon-Kuskokwim Delta rivers system.

Seven species of fish were surveyed for muscle tissue mercury content across a broad area of western Alaska. Total mercury levels were determined by cold vapor atomic fluorescence spectroscopy in 66 fish sampled during 1997. Methylmercury in sampled fish amounted to 97 to 100% of total mercury values. Using mercury consumption risk levels derived from U.S. Environmental Protection Agency hazard assessment models, mean total mercury was determined to be above the human critical value of 0.2 g/g (ppm) in 29% of the fish species, and 62% of the fish species contained mercury exceeding the wildlife critical value for piscivorous mammals. Overall, 24% of the fish exceed the critical value for human consumption and 58% the wildlife critical value. Similarly 31% of sites sampled exceeded the human consumption critical value. Based on the mean of all fish sampled and a small number of river otters, a biomagnification factor of 12 was calculated for the Yukon-Kuskokwim Delta Region of Alaska.

Seasonal variation of the amino acid, L-tryptophan, in interior Alaska.

The seasonal pattern of L-tryptophan was studied in a Fairbanks, Alaska, population that was unadapted to the extreme light variations of the North. Previously, this population was shown to exhibit seasonal behavior effects such as increases in fatigue and sleep duration, as well as endocrine effects such as increases in melatonin levels and phase shifting. Caloric and macronutrient intake have been reported to vary seasonally in humans, thereby potentially influencing the plasma levels of L-tryptophan, which is a precursor of serotonin and melatonin. Plasma levels of L-tryptophan from volunteers, whose average duration of stay in Alaska was eight months, were determined by automated amino acid analysis. Prominent results included finding increased levels in the winter at several different diurnal time points. These findings support hypotheses which relate underlying physiological adaptations to the North to the increased incidence of behavioral disorders such as depression and alcoholism.

Differences in faecal profiles of porphyrins among river otters exposed to the Exxon Valdez oil spill.

Abstract River otters (Lutra canadensis) living in marine environments of Prince William Sound, Alaska, exposed to crude oil from the Exxon Valdez spill in March 1989, showed significantly elevated levels of faecal porphyrin over those of otters from non-oiled areas (oiled mean = 48.2, andnon-oiled mean = 34.5 nmol g(-1) dry faeces). Profiles of uro-, hepta-, hexa-, penta-, copro-, andprotoporphyrin profiles were qualitatively characterized by high-performance liquid chromatography. These findings suggest that river otters may serve as a suitable indicator species in which porphyrin profiles can be used to monitor the effects of marine andfreshwater crude oil exposure. Also, this is the first model showing the effects of an oil spill on porphyrins on a free-ranging mammal using a non-lethal methodology. These effects were detectable 1 year after the spill andfollowing a major effort to clean oil from the shorelines of Prince William Sound.

Interaction of synthetic Alzheimer beta-protein-derived analogs with aqueous aluminum: a low-field 27Al NMR investigation.

Synthetic peptides corresponding to the soluble Alzheimer beta-protein, i.e., beta 1-40 and beta 6-25, were utilized to investigate the association of aluminum using low-field 27Al nuclear magnetic resonance (NMR) spectroscopy and reversed-phase high-performance liquid chromatography (RP-HPLC). Addition of beta 1-40 or beta 6-25 to aqueous Al3+ gives rise to a 27Al NMR signal corresponding to the association of Al3+ with the peptides; this effect is not easily reversed by EDTA. Based on the relative intensity of the Al(3+)-peptide signal between pH 4 and 6, there are at least 4 Al3+ ions associated with each peptide molecule. Microheterogeneity is observed with RP-HPLC on incubating solutions of Al3+ with beta 1-40 and beta 6-25. The 27Al NMR spectra of chromatographically pure fractions of beta 1-40 and beta 6-25 indicate that the peptide-associated Al3+ is released below pH 3.5. We propose that soluble beta 1-40 provides an anchor for Al3+ to bind, eventually leading to an increased deposition of amyloid in the Alzheimer brain.

Alcohol consumption and flushing response in natives of Chukotka, Siberia.

OBJECTIVE: Drinking patterns and flushing response were investigated among indigenous natives of Chukotka, Siberia (162 women, 139 men). The quantification of drinking behavior could be used for comparison with other northern peoples and as a baseline for future intervention. METHOD: Interviews, physical examinations and blood tests were performed in the Chukotka region of Siberia. RESULTS: 28% of the men and 4.5% of the women drank at least once per week. High doses per typical drinking occasion, which averaged 177.6 g of pure alcohol in men and 74.3 g in women, were reported; 10.3% of the men and 25.5% of the women reported that they experienced facial flushing after drinking. In most cases more than 20 g of alcohol was necessary to induce flushing, and two-thirds of the flushers were able to continue drinking after flushing began. No significant relationship between flushing and frequency and quantity of drinking and the prevalence of alcohol-related symptoms was found. There was a significant association between flushing by women and reports by them of their parent's flushing. CONCLUSIONS: Flushing by Chukotka natives and its relationship to drinking behavior is different from Oriental ALDH2-deficient flushing.