Negative interaction between indomethacin and exercise in mice.

We examined the possible negative interaction of the combined use of the NSAID indomethacin (IND) and exercise in mice. Mice were assigned to one of 4 groups: Exercise 2.5 mg/kg IND (Ex-2.5), Sedentary 2.5 mg/kg IND (Sed-2.5), Exercise 5.0 mg/kg IND (Ex-5.0) and Sedentary 5.0 mg/kg IND (Sed-5.0). Mice were given IND (gavage) 1 h prior to exercise (treadmill run at 30 m/min, 8% grade for 90 min) or rest for 14 consecutive days. Run times, body weight and mortality were recorded daily. Sed-5.0 was highly toxic and caused 70% mortality compared to Sed-2.5, which was well tolerated (0% mortality) (P<0.05). While the addition of exercise had no greater effect on mortality in Ex-5.0, it increased it in the 2.5 group (52% vs. 0%; P<0.05). Run time was reduced from baseline beginning on day 2 (Ex-5.0), or day 3 (Ex-2.5) (P<0.05). Body weight (recorded in the 2.5 mg/kg groups only) was decreased from baseline in Ex-2.5 and Sed-2.5 (P<0.05), but this effect occurred earlier and was of greater magnitude in Ex-2.5. Exercise combined with IND use can lead to serious side effects in mice. Future research is needed to test the hypothesis that this effect is due to increased GI permeability and whether humans are also at risk.

Mercury in fish scales as an assessment method for predicting muscle tissue mercury concentrations in largemouth bass.

The relationship between total mercury (Hg) concentration in fish scales and in tissues of largemouth bass (Micropterus salmoides) from 20 freshwater sites was developed and evaluated to determine whether scale analysis would allow a nonlethal and convenient method for predicting Hg concentrations in tissues. The relationship between total Hg concentration in untreated scale samples and muscle tissue is highly variable. Several different scale treatments were tried in an effort to increase the coefficient of determination and thereby enhance the effectiveness of this predictive technique. Washing scales with acetone, deionized (DI) water, detergent solution, and soap were used in conjunction with ultrasonication. The use of a mild soap solution with heating and ultrasonication increased the r(2) the most (from 0.69 [untreated scales] to 0.89). However, despite treatment, wide predictions of tissue Hg concentration remained. These results suggest that application of this technique as an independent method for issuance of fish advisories is inappropriate. Nevertheless, our results showed that scale analysis has potential for assessing general trends in concentration relative to a tissue criterion and for assessing Hg contamination in fish tissue as a first-level screen.

Using mussel isotope ratios to assess anthropogenic nitrogen inputs to freshwater ecosystems.

Stable nitrogen isotope ratios (delta15N) of freshwater mussels from a series of lakes and ponds were related to watershed land use characteristics to assess their utility in determining the source of nitrogen inputs to inland water bodies. Nitrogen isotope ratios measured in freshwater mussels from 19 lakes and ponds in Rhode Island, U.S.A., ranged from 4.9-12.6 per thousand and were found to significantly correlate with the fraction of residential development in 100 and 200 m buffer zones around the ponds. Mussel delta15N values in 12 of the 19 ponds also showed significant correlation with average dissolved nitrate concentrations, which ranged from 23-327 microg L(-1). These observations, in light of previous studies which link elevated delta15N values of nitrogen derived from septic wastewater with those seen in biota, suggest that mussel isotope ratios may reflect nitrogen source in freshwater ecosystems. We followed an iterative approach using multiple regression analysis to assess the relationship between mussel delta15N and the land use categories fraction residential development, fraction feedlot agriculture, fraction row-crop agriculture, and fraction natural vegetation in 100 and 200 m buffer zones and pond watersheds. From this we developed a simple regression model to predict mussel delta15N from the fraction of residential development in the 200 m buffer zone around the pond. Subsequent testing with data from 16 additional sites in the same ecoregion led us to refine the model by incorporating the fraction of natural vegetation. The overall average absolute difference between measured and predicted delta15N values using the two-parameter model was 1.6 per thousand. Potential sources of error in the model include differences in the scale and categorization of land-use data used to generate and test the model, differences in physical characteristics, such as retention time and range of residential development, and exclusion of sources of enriched nitrogen such as runoff from feedlot operations or increased nitrogen loading from inefficient or failed septic systems.

Association of prokaryotes with symptomatic appearance of withering syndrome in black abalone Haliotis cracherodii.

Withering syndrome (WS) is an epizootic fatal wasting disease that is devastating California Channel Island populations of black abalone Haliotis cracherodii. Our studies suggest a strong pathogen-disease association. The pathogen is an intracellular prokaryote that infects epithelial cells lining the gut and enzyme secreting cells of the digestive diverticula. It multiplies by binary fission in round to oval, basophilic, membrane-bound colonies teeming in the cytoplasm. Infection of the digestive diverticula is accompanied by a complete loss of digestive enzyme granules and metaplasia of enzyme secretory cells to a morphology similar to epithelium lining the gut. Extensive infection of digestive diverticular cells and the resultant deficiency in digestive enzymes correlates to the degree of pedal muscle atrophy and the severity of signs associated with WS. Electron microscopically the intracellular pathogen is a rod-shaped, ribosome-rich, gram-negative, prokaryote with a trilaminar cell wall consistent with the order Rickettsiales. Microbiological and protozoological methods produced no patterns that implicated other types of microbes. Chemical analysis of tissue from animals from a population with WS did not support an association between WS and environmental pollutant exposure to polycyclic aromatic hydrocarbons, polychlorinated biphenyls, or chlorinated pesticides.

Contaminant levels in harbor seals from the northeastern United States.

The concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzofurans (PCDF), polychlorinated dibenzo-p-dioxins (PCDD), and mercury (Hg) were determined in blubber and liver tissues of harbor seals (Phoca vitulina) collected along the northeast coast of the U.S. Average PCB concentrations in seal blubber (sum of congeners) were 12.0 micrograms/g (wet weight) with a range of 7.30 to 24.3 micrograms/g in 1980 and 6.66 micrograms/g (wet weight) with a range of 2.61 to 11.3 micrograms/g in 1990-1992. Comparisons between blubber data from this study and previous work indicated that the concentration of PCBs along the northeast coast of the U.S. may have decreased over the past twenty years. The average p,p'-DDE concentrations in seal blubber were 10.9 micrograms/g (wet weight) in 1980 with a range of 6.95 to 21.9 micrograms/g and 4.12 micrograms/g (wet weight) with a range of 1.83 to 7.84 micrograms/g in 1990-1992. Only trace amounts of PCDFs and PCDDs were found in a few blubber samples; levels in most tissues were below detection (3-5 pg/g) (wet weight). Trace amounts (< 30 ng/g) of phenanthracene, anthracene, and alkylated MW-178 compounds were found in some seal samples; all other PAH compounds were below the detection level (5-15 ng/g). Toxic equivalents (TEQ) of selected coplanar and mono-ortho PCB congeners and relative toxic equivalents (RTE) (pg total TEQ/microgram total PCB) were calculated, using recently proposed dioxin toxic equivalent factors (Ahlborg et al. 1994). The TEQs ranged from 41 to 315, and the RTEs ranged from 2.25 to 16.3.(ABSTRACT TRUNCATED AT 250 WORDS)

Hexachlorobenzene in selected marine samples: an environmental perspective.

Hexachlorobenzene (HCB) has been designated by the US Environmental Protection Agency as a chemical of interest. Re-examination of previously analysed gas chromatograms and archived samples revealed peaks that co-eluted with the authentic HCB standard. Levels of HCB were less than 1 ng/g in all samples re-examined, and were at least three to four orders of magnitude lower than those of poly-chlorinated biphenyls, two orders of magnitude lower than those of pyrene and one to two orders of magnitude lower than levels of either phenanthrene or benzo[a]-pyrene found in the same mussel samples. Chromatograms of sea water (dissolved and particulate phases) and sediments also revealed very low levels of HCB. Because gas chromatography-mass spectrometry results indicated that levels of HCB were below the level of detection it was not possible to verify its presence. The environmental data on HCB provided by the US Mussel Watch programme demonstrate that HCB levels in mussels are minor compared with other organic compounds such as polychlorinated biphenyls and polycyclic aromatic hydrocarbons (phenanthrene, pyrene and benzo[a]pyrene). Mussels were transplanted to areas affected by industrial activity and by disposal of sewage sludge and dredged materials, and in relatively clean reference sites. Transplanted mussels were used to monitor the marine food chain, as surrogates for other biota in the same areas and as sentinel organisms to monitor localized differences in biologically available chemical compounds. The degree of environmental threat posed by HCB in the marine environment, as indicated by the US Mussel Watch data, is relatively low. It is therefore recommended that a decision be made not to pursue an expanded HCB monitoring programme in the marine environment solely to collect more HCB data.

Amantadine in the treatment of refractory epilepsy in childhood: an open trial in 10 patients.

Amantadine HCl was given to 10 children with medically refractory seizures; other anticonvulsant medications were continued unchanged through the 12- to 16-week trial. Several patients noted improvement in control of myoclonic or atypical absence seizures. Tonic seizures were controlled in one patient, but worsened in another. Tonic-clonic and atonic seizures remained unchanged or worsened. Amantadine may be useful as an adjunctive anticonvulsant in some children with refractory atypical absence or myoclonic seizures.

Extraintestinal infections due to halophilic vibrios.

To compare the clinical and epidemiologic features, we reviewed the hospital records and interviewed 18 patients with extraintestinal infections caused by three species of halophilic vibrios. Vibrio vulnificus, the organism most frequently isolated in Virginia during the six-year study period, caused primary septicemia in three patients. Fifteen patients had soft tissue infections, most of which followed injuries that were contaminated by seawater and mostly caused by V vulnificus and V parahaemolyticus. All infections occurred during the warm months of the year, and in most cases were an occupational or recreational hazard of fishing.