Evaluation of water quality threats to the endangered Okaloosa darter (Etheostoma okaloosae) in East Turkey Creek on Eglin Air Force Base.

The threatened Okaloosa darter (Etheostoma okaloosae) is found almost exclusively on the Eglin Air Force Base in the Choctawhatchee Bay watershed of Florida. Portions of this limited habitat are threatened with soil erosion, altered hydrology, and impaired water quality. In the present study, general water quality parameters (i.e., dissolved oxygen, specific conductance, pH, temperature, relative turbidity, and primary productivity) were characterized in East Turkey Creek, which is a body of water potentially impacted by treated wastewater sprayfields, and Long Creek, an adjacent reference stream that does not border the sprayfields. Water quality was assessed during a 30-day exposure using passive samplers for both non-polar and polar effluent parameters. Because the Okaloosa darter was listed as endangered at the time of sampling we chose a closely related species from the same creeks, the sailfin shiner (Pteronotropis hypseleotris) in which to measure metal body burdens. Additionally, fathead minnows (Pimephales promelas) were used for microarray analysis on gonad and liver tissues after 48 h exposures to water collected from the two creeks and brought into the laboratory. Waters from all sites, including reference sites, affected the expression of genes related to various biological processes including transcription and translation, cell cycle control, metabolism, and signaling pathways, suggesting that the sum of anthropogenic compounds in the site waters may cause a generalized stress response in both liver and testis, an effect that could be related to the generally low populations of the Okaloosa darter. Furthermore, effects of site waters on fish gene expression may be related to the impact of human activities other than the wastewater sprayfields, as nearby areas are closed to the public for military testing, training, and administrative activities and due to ordnance contamination.

Pharmacokinetics and preliminary safety evaluation of azithromycin in adult horses.

Azithromycin is widely used in foals but has not been studied in adult horses. The goals of this study were to determine the pharmacokinetic profile and to make a preliminary assessment of the safety of azithromycin in adult horses. Azithromycin was administered intravenously (5 mg/kg) and intragastrically (10 mg/kg) to six healthy mares in a crossover design. Serial plasma samples, blood neutrophils, and pulmonary macrophages were collected for the measurement of azithromycin concentrations. Azithromycin was also administered orally (10 mg/kg) once a day for 5 days to five healthy mares for preliminary evaluation of safety in adult horses. The bioavailability of azithromycin following intragastric administration was 45 ± 12%. Concentrations within peripheral neutrophils and bronchoalveolar macrophages were several fold higher than that of plasma. Mild decreases in appetite (n = 3) and alterations in fecal consistency (n = 3) were noted following repeated oral administration. The pharmacokinetic profiles of azithromycin in adult horses, especially the slow elimination rate and intraneutrophil and intrapulmonary macrophage accumulation, demonstrate that it is conducive to use in this age group. Because of the gastrointestinal alterations noted, further studies are warranted before azithromycin can be recommended for use in adult horses.

An interlaboratory study of the pharmacokinetics of testosterone following intramuscular administration to Thoroughbred horses.

Testosterone is an anabolic androgenic steroid (AAS) that is endogenously produced by both male and female horses that also has the potential for abuse when administered exogenously to race horses. To recommend appropriate withdrawal guidelines so that veterinarians can discontinue therapeutic use prior to competition, the pharmacokinetics and elimination of testosterone were investigated. An aqueous testosterone suspension was administered intramuscularly in the neck of Thoroughbred horses (n = 20). The disposition of testosterone from this formulation was characterized by an initial, rapid absorption phase followed by a much more variable secondary absorption phase. The median terminal half-life was 39 h. A second focus of this study was to compare the testosterone concentrations determined by two different laboratories using a percentage similarity model with a coefficient of variation of 16.5% showing good agreement between the two laboratories results. Based on the results of this study, a withdrawal period of 30 days for aqueous testosterone administered IM is recommended.

Comparison between omega-3 and omega-6 polyunsaturated fatty acid intakes as assessed by a food frequency questionnaire and erythrocyte membrane fatty acid composition in young children.

OBJECTIVE: We conducted a dietary validation study in youth aged 1-11 years by comparing dietary intake of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) as assessed by a parent-completed semiquantitative food frequency questionnaire (FFQ) over time to erythrocyte membrane composition of the same fatty acids. DESIGN: The study population included youth aged 1-11 years who were participants in the Diabetes Autoimmunity Study in the Young (DAISY), a longitudinal study in Denver, Colorado that is following a cohort of youth at risk for developing type I diabetes. Four hundred and four children who had erythrocyte membrane fatty acid data matched to an FFQ corresponding to the same time frame for a total of 917 visits (matches) were included. PUFA intake was expressed both as g/day (adjusted for total energy) and as percent of total fat intake. We used mixed models to test the association and calculate the correlation between the erythrocyte membrane estimates and PUFA intake using all records of data for each youth. RESULTS: Intakes of total omega-3 fatty acids (beta=0.52, P<0.0001, rho=0.23) and marine PUFAs (beta=1.62, P<0.0001, rho=0.42), as a percent of total fat in the diet, were associated with percent of omega-3 and marine PUFAs in the erythrocyte membrane. Intakes of omega-6 PUFAs (beta=0.04, P=0.418, rho=0.05) and arachidonic acid (beta=0.31, P=0.774, rho=0.01) were not associated. CONCLUSIONS: In these young children, an FFQ using parental report provided estimates of average long-term intakes of marine PUFAs that correlated well with their erythrocyte cell membrane fatty acid status.

Organochlorine concentrations in bonnethead sharks (Sphyrna tiburo) from Four Florida Estuaries.

Because of their persistence in aquatic environments and ability to impair reproduction and other critical physiological processes, organochlorine (OC) contaminants pose significant health risks to marine organisms. Despite such concerns, few studies have investigated levels of OC exposure in sharks, which are fish particularly threatened by anthropogenic pollution because of their tendency to bioaccumulate and biomagnify environmental contaminants. The present study examined concentrations of 29 OC pesticides and total polychlorinated biphenyls (PCBs) in the bonnethead shark (Sphyrna tiburo), an abundant species for which evidence of reproductive impairment has been observed in certain Florida populations. Quantifiable levels of PCBs and 22 OC pesticides were detected via gas chromatography and mass spectrometry in liver of 95 S. tiburo from four estuaries on Florida's Gulf coast: Apalachicola Bay, Tampa Bay, Florida Bay, and Charlotte Harbor. In general, OC concentrations were significantly higher in Apalachicola Bay, Tampa Bay, and Charlotte Harbor S. tiburo in relation to the Florida Bay population. Because the rate of infertility has been shown to be dramatically higher in Tampa Bay versus Florida Bay S. tiburo, the present findings allude to a possible relationship between OC exposure and reproductive health that requires further investigation. Pesticide and PCB concentrations did not appear to significantly increase with growth or age in S. tiburo, suggesting limited potential for OC bioaccumulation in this species compared with other sharks for which contaminant data are available. Concentrations of OCs in serum and muscle were not correlated with those in liver, indicating that these tissues are poor surrogates for measuring internal OC burden in this species via nonlethal sampling procedures.

Lead content of calcium supplements.

CONTEXT: Substantial quantities of lead have been reported in some over-the-counter calcium supplement preparations, including not only bone-meal and dolomite, but also over-the-counter natural and refined calcium carbonate formulations. Examination of this issue is warranted given recent increases in physician recommendations for calcium supplements for prevention and treatment of osteoporosis. OBJECTIVES: To determine the lead content of calcium supplements and to quantify the lead exposure from popular brands of calcium in dosages used for childhood recommended daily allowance, osteoporosis, and phosphate binding in dialysis patients. DESIGN AND SETTING: Analysis of lead content in 21 formulations of nonprescription calcium carbonate (including 7 natural [ie, oyster shell] and 14 refined), 1 brand of prescription-only calcium acetate, and 1 noncalcium synthetic phosphate binder conducted in March 2000. MAIN OUTCOME MEASURES: Lead content, assayed using electrothermal atomic absorption, expressed as micrograms of lead per 800 mg/d of elemental calcium, per 1500 mg/d of calcium, and for a range of dosages for patients with renal failure. Six microg/d of lead was considered the absolute dietary limit, with no more than 1 microg/d being the goal for supplements. RESULTS: Four of 7 natural products had measurable lead content, amounting to approximately 1 microg/d for 800 mg/d of calcium, between 1 and 2 microg/d for 1500 mg/d of calcium, and up to 10 microg/d for renal dosages. Four of the 14 refined products had similar lead content, including up to 3 microg/d of lead in osteoporosis calcium dosages and up to 20 microg/d in high renal dosages. No lead was detected in the calcium acetate or polymer products. Lead was present even in some brand name products from major pharmaceutical companies not of natural oyster shell derivation. CONCLUSIONS: Despite increasingly stringent limits of lead exposure, many calcium supplement formulations contain lead and thereby may pose an easily avoidable public health concern. JAMA. 2000;284:1425-1429.

Surface-enhanced Raman scattering from an etched polymer substrate.

An etched polymer was evaluated as a substrate suitable for routine SER analysis and was found to perform similarly to crossed gratings and posted quartz wafers. Silver particles were layered onto sheets of etched poly(ethylene terephthalate) by chemical reduction, sputtering, and vapor deposition. Enhancement factors ranged from 10(4) to >10(5) for crystal violet on chemically reduced and sputtered surfaces, respectively. Ranges of linearity up to 3 orders of magnitude were attained with limits of detection of ∼5 pg. The variability of response was <20% RSD for both routinely and painstakingly prepared samples. To induce enhancements beyond those possible from the dry substrate, a thin film of water was held on the analyte-treated substrate surface in a liquid state. Typical spectra of nine analytes with amino, carboxylate, and/or nitro groups were collected from the most active substrate.