bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms underlying duodeno‐gastric reflux in man
Authors: Koek G. H. , Vos R. , Sifrim D. , Cuomo R. , Janssens J. , Tack J.
Published: March 2005

Abstract  Background:  Recent studies suggest that duodeno‐gastro‐oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno‐gastric reflux (DGR), a prerequisite for DGER, are poorly understood.

Aims:  To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility.

Subjects and methods:  Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec® recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially.

Results:  During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 ± 28 min after the start of the meal, and was cleared from the stomach after 242 ± 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin‐induced gastric phase III and erythromycin‐induced DGR clearance.

Conclusion:  In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III.
The urological management of the patient with acquired immunodeficiency syndrome
Authors: Heyns Chris F. , Fisher Megan
Published: March 2005

In people infected with the human immunodeficiency virus (HIV) both the CD4 T‐cell count and the viral load are used to monitor disease progression to acquired immunodeficiency syndrome (AIDS). CD4 counts of <500/mm3 are associated with opportunistic infections and certain malignancies, so‐called ‘AIDS‐defining’ conditions. Highly active antiretroviral therapy, using combinations of reverse transcriptase inhibitors and/or protease inhibitors, can improve considerably the prognosis of people who are HIV‐positive, but such therapy is not yet widely available in many developing countries. People with AIDS are predisposed to urinary tract infection (UTI) by uncommon bacteria and pathogens, e.g. fungi, parasites and viruses, which may affect any urogenital organ; treatment should be culture‐specific and long‐term, because there is a tendency to recurrence, infection with multiple organisms and resistant isolates. Voiding dysfunction in patients with AIDS is usually a result of neurological complications caused by opportunistic infections, and has a poor prognosis. Of patients with AIDS, 30–50% develop a cancer, especially Kaposi's sarcoma (KS) and non‐Hodgkin's lymphoma (NHL). KS may involve any urogenital organ, but is usually part of systemic disease. Small lesions on the external genitalia can be treated with laser, cryotherapy or surgical excision, larger lesions with radiotherapy, and disseminated or visceral KS with multidrug chemotherapy. NHL may involve the kidneys, testes and retroperitoneal lymph nodes, thus obstructing the ureters, which may require ureteric stenting or percutaneous nephrostomy. NHL can be treated with radiotherapy and combination chemotherapy. Urolithiasis in patients with AIDS may be caused by indinavir, a protease inhibitor, but the more common types of stones may also occur. Fluid‐electrolyte and acid‐base disturbances are common in patients with advanced AIDS, secondary to vomiting, diarrhoea, malnutrition or septicaemia. HIV‐associated nephropathy occurs in 10–30% of patients, and often leads to renal failure. Testicular atrophy is common, leading to infertility, erectile dysfunction (ED) and decreased libido. Treatment for ED must include counselling about strategies to reduce the transmission of HIV. The risk of HIV transmission after parenteral exposure to blood from an HIV‐positive patient is relatively low (0.2–0.4%); the urologist can reduce the risk of transmission during surgery by adopting certain precautions. After occupational exposure to HIV, chemoprophylaxis with antiretroviral medication can significantly reduce the probability of HIV transmission.
Dietary isoflavones during pregnancy and lactation provide cardioprotection to offspring rats in adulthood
Authors: Souzeau Emmanuelle , Bélanger Sonia , Picard Sylvie , Deschepper Christian F.
Published: March 2005

In adult rats, elongation of cardiac myocytes (CMs) correlates with dilatation (and sometimes dysfunction) of cardiac ventricles. Although sex steroids may constitute one possible factor that affects the dimensions of CMs, studies on their effects in rodents is complicated by the fact that most commercial soy-based diets also contain abundant phytoestrogens. We report that feeding Wistar-Kyoto rat dams during gestation and lactation with a phytoestrogen-rich soy-based diet caused the CMs of their adult offspring to be shorter than in counterparts originating from mothers fed with a phytoestrogen-free casein-based diet. The soy-based diet had no such effects when given to rats after 6 wk of age, and its effects were replicated when supplementing the maternal casein-based diet with the isoflavones daidzein and genistein (the most abundant phytoestrogens in soy-based diets). In contrast to rats whose mothers had been fed with a soy-based diet, the hearts of adult rats raised with a casein-based diet only featured dilated eccentric hypertrophy and progressed toward congestive heart failure when further challenged. Thus the presence of isoflavones in the maternal diet provides cardioprotection to the hearts of their offspring during adulthood.
Simulated microgravity produces attenuated baroreflex-mediated pressor, chronotropic, and inotropic responses in mice
Authors: Jung Albert S. , Harrison Robert , Lee Kwang H. , Genut Jordan , Nyhan Daniel , Brooks-Asplund E. M. , Shoukas Artin A. , Hare Joshua M. , Berkowitz Dan E.
Published: March 2005

Whether myocardial contractile impairment contributes to orthostatic intolerance (OI) is controversial. Accordingly, we used transient bilateral carotid occlusion (TBCO) to compare the in vivo pressor, chronotropic, and inotropic responses ( parts 1 and 2) to open-loop selective carotid baroreceptor unloading in anesthetized mice. In part 3, in vitro myocyte responses to isoproterenol in mice exposed to hindlimb unweighting (HLU) for ∼2 wk were determined. Heart rate (HR) and mean arterial pressure (MAP) responses to TBCO were measured. In control mice, TBCO increased HR (15 ± 2 beats/min, P < 0.05) and MAP (17 ± 2 mmHg, P < 0.05). These responses were markedly potentiated in denervated control (DC) mice, in which the aortic depressor nerve and sympathetic trunk were sectioned before measurement. Baroreflex responses to TBCO were eliminated by blockade with hexamethonium bromide (10 μg/kg). In HLU (denervated) mice, HR and MAP responses were reduced ∼70% compared with DC mice. In part 2, myocardial contractile responses to TBCO were measured with a left ventricular micromanometer-conductance catheter. TBCO in DC mice increased the slope of the end-systolic pressure-volume relation (end-systolic elastance) by 86 ± 13%. This inotropic response was attenuated (14 ± 10%, P < 0.005) after HLU. In part 3, contractile responses to isoproterenol were impaired in myocytes isolated from HLU mice. In conclusion, selective carotid baroreceptor unloading stimulates HR, blood pressure, and myocardial contractility, and HLU attenuates each response. These findings have important implications for the management of OI in astronauts, the elderly, and individuals subjected to prolonged bed rest.
Heterogeneous vasodilator responses of human limbs: influence of age and habitual endurance training
Authors: Newcomer Sean C. , Leuenberger Urs A. , Hogeman Cynthia S. , Proctor David N.
Published: March 2005

Forearm endothelium-dependent vasodilation is impaired with age in sedentary, but not endurance-trained, men. The purpose of this investigation was to determine whether these age- and physical activity-related differences in endothelium-dependent vasodilation also occur in the leg. Brachial and common femoral arterial blood flow were measured with Doppler ultrasound during increasing doses of acetylcholine (1, 4, and 16 μg·100 ml limb tissue−1·min−1), substance P (8, 31, and 125 pg·100 ml limb tissue−1·min−1), and sodium nitroprusside (0.063, 0.25, and 1 μg·100 ml limb tissue−1·min−1) in 23 healthy men (8 younger sedentary, 8 older sedentary, and 7 older endurance trained). Increases in forearm blood flow to the highest dose of acetylcholine and sodium nitroprusside were smaller ( P < 0.05) in older sedentary (841 ± 142%, 428 ± 74%) compared with younger sedentary (1,519 ± 256%, 925 ± 163%) subjects. Similarly, increases in forearm blood flow to sodium nitroprusside (1 μg·100 ml limb tissue−1·min−1) were smaller ( P < 0.05) in older endurance-trained (505 ± 110%) compared with younger sedentary (925 ± 163%) subjects. In contrast, no differences in leg blood flow responses to intra-arterial infusions of acetylcholine, substance P, or sodium nitroprusside were noted between subject groups. These results demonstrate that 1) acetylcholine- and sodium nitroprusside-induced vasodilation are attenuated in the forearm vasculature and preserved in the leg vasculature of older sedentary subjects and 2) sodium nitroprusside-induced vasodilation remains attenuated in the forearm vasculature of healthy older endurance-trained men but preserved in the leg vasculature of these men.
MRI-based finite-element analysis of left ventricular aneurysm
Authors: Walker Joseph C. , Ratcliffe Mark B. , Zhang Peng , Wallace Arthur W. , Fata Bahar , Hsu Edward W. , Saloner David , Guccione Julius M.
Published: March 2005

Tagged MRI and finite-element (FE) analysis are valuable tools in analyzing cardiac mechanics. To determine systolic material parameters in three-dimensional stress-strain relationships, we used tagged MRI to validate FE models of left ventricular (LV) aneurysm. Five sheep underwent anteroapical myocardial infarction (25% of LV mass) and 22 wk later underwent tagged MRI. Asymmetric FE models of the LV were formed to in vivo geometry from MRI and included aneurysm material properties measured with biaxial stretching, LV pressure measurements, and myofiber helix angles measured with diffusion tensor MRI. Systolic material parameters were determined that enabled FE models to reproduce midwall, systolic myocardial strains from tagged MRI (630 ± 187 strain comparisons/animal). When contractile stress equal to 40% of the myofiber stress was added transverse to the muscle fiber, myocardial strain agreement improved by 27% between FE model predictions and experimental measurements (RMS error decreased from 0.074 ± 0.016 to 0.054 ± 0.011, P < 0.05). In infarct border zone (BZ), end-systolic midwall stress was elevated in both fiber (24.2 ± 2.7 to 29.9 ± 2.4 kPa, P < 0.01) and cross-fiber (5.5 ± 0.7 to 11.7 ± 1.3 kPa, P = 0.02) directions relative to noninfarct regions. Contrary to previous hypotheses but consistent with biaxial stretching experiments, active cross-fiber stress development is an integral part of LV systole; FE analysis with only uniaxial contracting stress is insufficient. Stress calculations from these validated models show 24% increase in fiber stress and 115% increase in cross-fiber stress at the BZ relative to remote regions, which may contribute to LV remodeling.
Origin and Uses of Primum Non Nocere—Above All, Do No Harm!
Authors: Smith Cedric M.
Published: March 2005

The so‐called Hippocratic injunction to do no harm has been an axiom central to clinical pharmacology and to the education of medical and graduate students. With the recent reexamination of the nature and magnitude of adverse reactions to drugs, the purposes of this research and review were to discover the origin of this unique Latin expression. It has been reported that the author was neither Hippocrates nor Galen. Searches of writings back to the Middle Ages have uncovered the appearance of the axiom as expressed in English, coupled with its unique Latin, in 1860, with attribution to the English physician, Thomas Sydenham. Commonly used in the late 1800s into the early decades of the 1900s, it was nearly exclusively transmitted orally; it rarely appeared in print in the early 20th century. Its applicability and limitations as a guide to the ethical practice of medicine and pharmacological research are discussed. Despite insufficiencies, it remains a potent reminder that every medical and pharmacological decision carries the potential for harm.
Balancing Work and Family: Equity, Gender, and Marital Satisfaction
Authors: Saginak Kelli A. , Saginak M. Alan
Published: March 2005

Answers as to how working couples successfully balance work and family continue to interest social science researchers. Creating a balance presents couples with numerous challenges that place strain on relationships and marriages. Marital satisfaction is significantly related to how couples negotiate their work-family demands and responsibilities. Gender often influences couples’ definitions and perceptions of those demands and responsibilities. This literature review summarizes recent research on marital satisfaction as it relates to couples’ division of labor and perceptions of equity and fairness, specifically as it relates to gender ideologies. Adaptive strategies and practical considerations are discussed, and implications for future research are identified including cultural and socioeconomic considerations.
At the Confluence of Memory and Meaning—Life Review With Older Adults and Families: Using Narrative Therapy and the Expressive Arts to Re-member and Re-author Stories of Resilience
Authors: Caldwell Rebecca L.
Published: March 2005

In this article, the author focuses on ways in which counselors can adapt narrative therapy and expressive arts therapy techniques to cultivate and support their clients’ creativity for use in the life review process. The counselor acts in a cocreative and consultative role, drawing on the client’s expertise about his or her own life and constructing a collaborative process that also can engage the client’s family, caregivers, and important others in the client’s community. The writer suggests expressive arts techniques such as bibliotherapy, journaling, and the making of memory books, self boxes, life maps, and time capsules, along with videography as among a myriad of ways to tap into an ongoing creative meaning-making process necessary for life review. The collaborative process described facilitates deconstructing problem stories and constructing unique outcomes in their place for the client and quite possibly for the family and important others.
Accumulation of ligands for aryl hydrocarbon and sex steroid receptors in fish exposed to treated effluent from a bleached sulfite/groundwood pulp and paper mill
Authors: Hewitt L. Mark , Pryce Andrea C. , Parrott Joanne L. , Marlatt Vicki , Wood Craig , Oakes Kenneth , Van Der Kraak Glen J.
Published: March 2005

The accumulation of ligands for the aryl hydrocarbon receptor (AhR) and fish sex steroid receptors was investigated using two separate controlled fish exposures to final effluent from a bleached sulfite/groundwood mill in New Brunswick, Canada. In the first experiment, hepatic tissue extracts from exposed fish were fractionated according to lipophilicity. Fractions with different octanol-water (Kow) partition coefficients were tested for the presence of bioavailable chemicals that function as ligands for the AhR in H4IIE cells, rainbow trout hepatic estrogen receptors (ER), goldfish testicular androgen receptors (AR), and goldfish sex steroid binding protein (SSBP). Fish accumulated ligands for each receptor after 4-d exposure to effluent. Single fractions contained ligands for the AhR and the ER, while multiple fractions competed for the AR and SSBP. Fish also accumulated ligands for the AhR and SSBP from Saint John River dilution water, indicating upstream sources of bioactive substances. Semipermeable-membrane devices deployed concurrently with fish accumulated ligands from effluent for all receptors except the ER. In the second experiment, accumulated ligands were evaluated after exposure of fish to effluent for two different durations and following a depuration period. Hepatic mixed function oxygenase activity and whole-liver hormonal activity, measured as binding to SSBP, returned to background following 6 d depuration and were reduced but still significant after 12-d exposure to effluent. Whole-liver extract affinities for the AR were maintained after extended exposure and depuration, indicating the potential for AR ligands to bioaccumulate. The accumulation of AhR ligands and ligands for sex steroid receptors provides a mechanistic linkage to effects on growth, development, and performance of fish exposed to effluent from this and other mills.
Changes in growth and secondary sex characteristics of fathead minnows exposed to bleached sulfite mill effluent
Authors: Parrott Joanne L. , Wood Craig S. , Boutot Peter , Dunn Susan
Published: March 2005

Yellow perch captured downstream of a bleached sulfite mill had reduced gonads zeandfecundity, and circulating steroid levels declined in goldfish exposed to final effluent for 21 d. To assess bleached sulfite mill (BSM) effluent, long-term fathead minnow (Pimephales promelas) growth and reproduction tests were carried out in a flow-through bioassay trailer at the mill secondary treatment lagoons. Fertilized P. promelas eggs were hatched in effluent (0, 1, 3.2, 10, 32, 50, and 100% final effluent with 10 ng/L ethinylestradiol as a positive control compound) and monitored through to 30, 60, and 125 d posthatch. The effluent caused a significant increase in the growth of fish; this effect was evident within 30 d. Fish had changes in secondary sex characteristics at maturity: Male fish had ovipositors in effluent concentrations as low as 3.2%. Higher effluent concentrations (32–100%) resulted in a majority of fish that looked externally like females. Changes in external sex characteristics were the most sensitive endocrine disruption–specific endpoints and required four months of exposure. Exposure to low BSM effluent concentrations (3.2%) resulted in female fish that had male sex characteristics (tubercles and dorsal fin dots). This masculinization of female fish was statistically significant at 10% effluent and was not seen in control fish. Concentrations of final effluent in the Saint John River (Canada) range from less than 1% to 15%, depending on the season and river flow. The research assesses some of the changes seen in fathead minnows exposed to this complex effluent, and demonstrates a threshold of <10% BSM effluent for the most sensitive effects.
Effects of pulp mill effluent on benthic assemblages in mesocosms along the Saint John River, Canada
Authors: Culp Joseph M. , Cash Kevin J. , Glozier Nancy E. , Brua Robert B.
Published: March 2005

We used mesocosms toexamine the impact of different concentrations of pulp mill effluent (PME) on structural and functional endpoints of a benthic assemblage in the Saint John River (NB, Canada) during 1999 and 2000. Previous studies on this effluent's effects produced conflicting results, with field surveys suggesting a pattern of mild nutrient enrichment, while laboratory toxicity tests linked effluent exposure to moderate contaminant effects. Experimental treatments included three concentrations of sulfite pulp mill effluent (0, 5, 10% v/v PME). Endpoints for the assessment included algal biomass and taxonomic composition, benthic invertebrate abundance and composition, and insect emergence. Low concentrations of PME increased periphyton biomass and caused changes in community structure within the diatom-dominated community. Pulp mill effluent addition had little effect on several structural endpoints measured for benthic invertebrates, including abundance and taxonomic richness, but significantly changed community composition. For both periphyton and benthic invertebrates, community composition endpoints were more sensitive indicators of PME exposure. Insect emergence was a highly relevant functional endpoint. When benthic and emerged insects were combined, total abundance increased with PME addition. Results from two trophic levels, which provided multiple lines of evidence, indicated that the main impact of these PME concentrations is nutrient enrichment rather than effluent toxicity. Our findings also suggest that benthic invertebrate and periphyton assemblages, algal biomass production, and insect emergence are sensitive response measures. Future studies may confirm this observation. The consideration of both functional and structural endpoints at different trophic levels can greatly improve our understanding the effects of discharges to rivers. Such an understanding could not have been obtained using standard assessment techniques and illustrates the value of mesocosms and the benthic community assemblage approach in environmental assessment.
Source of toxicity in storm water: Zinc from commonly used paint
Authors: Kszos Lynn Adams , Morris Gail W. , Konetsky Belinda K.
Published: March 2005

A Department of Energy site in Paducah, Kentucky (USA), stores thousands of cylinders of depleted uranium hexa-fluoride. Breaches of the cylinders could result in the release of uranium and hydrogen fluoride. Beginning in 1996, a program was begun to paint the cylinders in order to prevent corrosion of the cylinders and the surfaces of the storage yards were converted to concrete. In 1998, storm water from the cylinder storage yards was found to be toxic to Ceriodaphnia, at concentrations exceeding limits in the site's discharge permit. A six-month study was conducted to identify the source of the toxicity in the storm water. Ceriodaphnia toxicity tests with the storm water resulted in 48-h median lethal concentrations (LC50) ranging from 12 to 94%; zinc concentrations in the storm water ranged from 0.08 to 0.54 mg/L. Acute toxicity tests with zinc and linear regression identified that zinc concentrations in the storm water were sufficient to account for the toxicity observed. By tracking the sources to the discharge point, newly painted cylinders were identified as the source of the zinc in the storm water. Rainwater collected directly from the painted cylinders contained up to 13 mg Zn/L. Laboratory and field tests showed that topcoating the cylinders would reduce the amount of zinc in the runoff from the cylinders.
Sensitivity of water tupelo (Nyssa aquatica) and bald cypress (Taxodium distichum) seedlings to manganese enrichment under water-saturated conditions
Authors: McLeod Kenneth W. , Ciravolo Thomas G.
Published: March 2005

In anaerobic soils of wetlands, Mn is highly available to plants because of the decreasing redox potential and pH of flooded soil. When growing adjacent to each another in wetland forests, water tupelo (Nyssa aquatica L.) had 10 times greater leaf manganese concentration than bald cypress (Taxodium distichum [L.] Richard). This interspecific difference was examined over a range of manganese-enriched soil conditions in a greenhouse experiment. Water tupelo and bald cypress seedlings were grown in fertilized potting soil enriched with 0, 40, 80, 160, 240, 320, and 400 mg Mn/L of soil and kept at saturated to slightly flooded conditions. Leaf Mn concentration was greater in water tupelo than bald cypress for all but the highest Mn addition treatment. Growth of water tupelo seedlings was adversely affected in treatments greater than 160 mg Mn/L. Total biomass of water tupelo in the highest Mn treatment was less than 50% of the control. At low levels of added Mn, bald cypress was able to restrict uptake of Mn at the roots with resulting low leaf Mn concentrations. Once that root restriction was exceeded, Mn concentration in bald cypress leaves increased greatly with treatment; that is, the highest treatment was 40 times greater than control (4,603 vs 100 μg/g, respectively), but biomass of bald cypress was unaffected by manganese additions. Bald cypress, a tree that does not naturally accumulate manganese, does so under manganese-enriched conditions and without biomass reduction in contrast to water tupelo, which is severely affected by higher soil Mn concentrations. Thus, bald cypress would be less affected by increased manganese availability in swamps receiving acidic inputs such as acid mine drainage, acid rain, or oxidization of pyritic soils.
Biotransformation and genotoxicity of fluoranthene in the deposit-feeding polychaete Capitella sp. I
Authors: Palmqvist Annemette , Selck Henriette , Rasmussen Lene Juel , Forbes Valery E.
Published: March 2005

Polycyclic aromatic hydrocarbons, such as fluoranthene (Flu), are of environmental concern because of their persistence, toxicity, and mutagenic properties. In this study we examined the genotoxicity of Flu to Capitella sp. I using the comet assay. We assessed patterns of DNA damage as a function of uptake route and as a function of exposure and depuration time and related levels of DNA damage to published information on Flu-metabolite formation. Exposure to approximately 30 μg Flu/g dry-weight sediment or 50 μg Flu/L seawater resulted in significant DNA damage. The degree of DNA damage was time dependent during both exposure and depuration, and although exposure route had no effect on the maximum degree of DNA damage occurring, it did influence the time course of damage. Levels of damage declined despite continued exposure to Flu, providing evidence for the induction of one or more DNA repair mechanisms. Comparison with Flu-metabolite profiles suggests that DNA damage is associated with the production of aqueous metabolites. The transitory nature of the DNA damage and repair process may contribute important insights into the mechanisms of toxicant effects at the molecular level but limits the usefulness of such endpoints as biomarkers of exposure or effect in ecotoxicological studies.
The relationship between disinfection by-product formation and structural characteristics of humic substances in chloramination
Authors: Wu Wells W. , Chadik Paul A. , Delfino Joseph J.
Published: March 2005

The influence of structural characteristics of humic substances on disinfection by-product (DBP) formation was investigated for seven humic substances isolated from aquatic and terrestrial sources. The structural characterizations included 13C nuclear magnetic resonance (13C NMR) spectroscopy and ultraviolet (UV) spectroscopy. The aqueous humic substances were chloraminated at pH 7.0 and 8.5, with and without the presence of the bromide ion, and analyzed for total organic halogen (TOX), trihalomethanes (THMs), and haloacetic acids (HAAs). Aromatic contents determined by 13C NMR and differential UV absorbance at 254 nm statistically correlated with TOX formation for the humic substances investigated at p < 0.08. In contrast, a lack of correlation was observed for THM and HAA formation and these parameters. This paper also compiles relevant literature and discusses the contrasting reaction response of DBP precursor material to chlorination and chloramination.
A method for predicting bioavailability of rare earth elements in soils to maize
Authors: Wang Wei-Sheng , Shan Xiao-Quan , Wen Bei , Zhang Shu-Zhen
Published: March 2005

A single-extraction procedure using low-molecular-weight organic acids (LMWOA) as extractant and the first and second steps of a three-step extraction procedure recommended by the European Community Bureau of Reference (BCR; now European Community Standards, Measurement and Testing Programme, Brussels, Belgium) were performed to extract the light rare earth elements (LREEs) La, Ce, Pr, and Nd from wet rhizosphere soil. The extracted soil solutions were successively filtered through membranes with a pore size of less than 0.45 μm and a molecular weight cutoff of less than 1 kDa, which were termed colloidal and truly dissolved fractions, respectively. Apoplastically and symplastically bound LREEs in maize roots were experimentally distinguished by ultrasound-assisted desorption with 1 mM CaCl2 solution at 0°C in ice-cooled water bath. When the LMWOAs extraction method was used, a good correlation was obtained between LREEs in soil colloidal and truly dissolved fractions and LREEs bound to apoplasm and symplasm of maize root. Both apoplastically and symplastically bound LREEs are the result of bioavailability. However, a poor correlation was obtained between LREEs in fractions water soluble, exchangeable and carbonate bound (B1) and Fe-Mn oxide bound (B2) of the BCR method and LREEs in apoplasm and symplasm and in intact roots. Hence, the LMWOAs extraction method is recommended for measuring the bioavailability of LREEs in soils.
Copper tolerance in fathead minnows: I. The role of genetic and nongenetic factors
Authors: Kolok Alan S. , Peake Elizabeth B. , Tierney Laura L. , Roark Shaun A. , Noble Robert B. , See Kyoungah , Guttman Sheldon I.
Published: March 2005

Swim performances of male and female fathead minnows (Pimephales promelas) from three different suppliers were determined before and after an 8- to 9-d exposure to 175 μg/L copper (Cu). The reduction in swim performance (delta) due to the Cu exposure varied widely among individual fish, but was surprisingly consistent from one supplier to the next and between males and females. Genetic analysis of the individuals revealed significant correlations between delta and genotypic variation at the glucosephosphate isomerase-1, phosphoglucomutase-1, and lactate dehydrogenase-2 enzyme loci. Based upon delta, the most Cu-resistant fathead minnows were bred together, as were the most Cu-susceptible individuals and two groups of unselected minnows. Larvae produced by each group of adults were subjected to a survival test. The median lethal concentration (LC50) for larvae produced by Cu-resistant adults was significantly greater than the LC50s for the control groups. Surprisingly, the LC50 for the larvae produced by Cu-susceptible adults was also significantly greater than the LC50s for the control groups, but not significantly different from the larvae produced by Cu-resistant parents. While Cu tolerance has a genetic component in fathead minnows, the Cu tolerance of larval fish appears to be influenced by nongenetic as well as genetic factors.
Metallothionein-like protein in the least killifish Heterandria formosa and its role in cadmium resistance
Authors: Xie Lingtian , Klerks Paul L.
Published: March 2005

Metallothioneins (MTs) are a class of low molecular weight, cysteine-rich, metal-binding proteins ubiquitous in animals. They function in metal regulation and detoxification. An MT-like protein was separated by gel-permeation high-performance liquid chromatography (HPLC) in the least killifish Heterandria formosa exposed to 6 mg/L of Cd for 26 h. Western blot analysis showed that this protein cross-reacted with a cod-MT antibody. We quantified MT-like protein levels by the Cd-hemoglobin saturation assay in fish from two Cd-resistant and two control laboratory populations. Fish from the resistant populations had higher MT-like protein levels than those from the control populations; this difference was found for basal levels and for levels after 26 h of exposure to Cd. Our results suggest that the MT-like protein detoxified Cd in the least killifish and accounted for at least part of the increased resistance in the Cd-resistant laboratory populations.
Influence of water quality and age on nickel toxicity to fathead minnows (Pimephales promelas)
Authors: Hoang Tham Chung , Tomasso Joseph R. , Klaine Stephen J.
Published: March 2005

This research characterized the effects of water quality and organism age on the toxicity of nickel (Ni)to fathead minnows (Pimephales promelas) to facilitate the accurate development of site-specific water-quality criteria. Nickel sulfate hexa-hydrate (NiSO4·6H2O) was used as the Ni source for performing acute toxicity tests (median lethal concentration after 96-h exposure [96-h LC50]) with <1-d-old and 28-d-old P. promelas under varying regimes of hardness, pH, alkalinity, and natural organic matter (NOM). The toxicity of Ni was inversely related to water hardness between hardness values of 20 and 150 mg/L (as CaCO3). Below 30 mg/L alkalinity, Ni toxicity was related to alkalinity. The effect of pH was confounded by hardness and the presence of NOM. In the absence of NOM, the toxicity of Ni increased as pH increased at high hardness and alkalinity. In general, 28-d-old fish were less sensitive than <1-d-old fish to Ni. This lower sensitivity ranged from 12-fold at low hardness and alkalinity (20 and 4 mg/L, respectively) to 5-fold at high hardness and alkalinity (100 and 400 mg/L, respectively). The presence of NOM (10 mg/L as dissolved organic carbon [DOC]) reduced Ni toxicity by up to 50%, but this effect appeared to be saturated above DOC at 5 mg/L. Incubating Ni with the NOM solution from 1 to 17 days had no effect on Ni toxicity. When using multivariate analysis, the 96-h LC50 for Ni was a function offish age, alkalinity, hardness, and NOM (96-h LC50 = −0.642 + 0.270(fish age) + 0.005(alkalinity) + 0.018(hardness) + 0.138(DOC)). When using this model, we found a strong relationship between measured and predicted 96-h LC50 values (r2 = 0.94) throughout the treatment water qualities. The biotic ligand model (BLM) did not accurately predict Ni toxicity at high or low levels of alkalinity. Results of our research suggest that the BLM could be improved by considering NiCO3 to be bioavailable.
Mercury accumulation and loss in mallard eggs
Authors: Heinz Gary H. , Hoffman David J.
Published: March 2005

Female mallards (Anas platyrhynchos) were fed diets containing 5, 10, or 20 ppm mercury as methylmercury chloride. One egg was collected from each bird before the start of the mercury diets and 15 eggs were collected from each bird while it was being fed mercury. The mercury diets were then replaced by uncontaminated diets, and each female was allowed to lay 29 more eggs. Mercury levels in eggs rose to about 7, 18, and 35 ppm wet-weight in females fed 5, 10, or 20 ppm mercury, respectively. Mercury levels fell to about 0.16, 0.80, and 1.7 ppm in the last egg laid by birds that had earlier been fed 5, 10, or 20 ppm mercury, respectively. Higher concentrations of mercury were found in egg albumen than in yolk, and between 95 and 100% of the mercury in the eggs was in the form of methylmercury.
Estrogenic potential of halogenated derivatives of nonylphenol ethoxylates and carboxylates
Authors: García-Reyero Natàlia , Requena Vanessa , Petrovic Mira , Fischer Birgit , Hansen Peter-Diedrich , Díaz Alfredo , Ventura Francesc , Barceló Damiá , Piña Benjamin
Published: March 2005

Hlogenated derivatives of nonylphenol and of its alkylates are generated during drinking water disinfection and treatment procedures. In this paper we analyze the potential of these compounds to interact with the estrogen receptor and to activate hormone-regulated gene promoters. We used the recombinant yeast assay (RYA) and the human breast cancer cell MCF7 proliferation assay for both estrogenic and antiestrogenic activities and the enzyme-linked receptor assay to examine in vitro binding to the receptor Many nonylphenol derivatives were very weak estrogens in our functional tests when compared to nonylphenol while retaining a substantial affinity for the estrogen receptor in vitro. Antiestrogenicity tests demonstrated that brominated nonylphenol and most of the carboxylated compounds studied here behaved as estrogenic antagonists in the RYA. We also detected an increased cytotoxicity for the carboxylated derivatives in both yeast and mammalian cells. We conclude that derivatization may mask the apparent estrogenicity of nonylphenol, but the resulting compounds still represent a potential hazard since they are still able to bind the estrogen receptor and to influence the physiological response to estrogens. Our results also illustrate the advantage of combining different methods to assay estrogenicity of unknown substances.
Importance of equilibration time in the partitioning and toxicity of zinc in spiked sediment bioassays
Authors: Lee Jung-Suk , Lee Byeong-Gweon , Luoma Samuel N. , Yoo Hoon
Published: March 2005

The influences of spiked Zn concentrations (1–40 μmol/g) and equilibration time (˜ 95 d) on the partitioning of Zn between pore water (PW) and sediment were evaluated with estuarine sediments containing two levels (5 and 15 μmol/g) of acid volatile sulfides (AVS). Their influence on Zn bioavailability was also evaluated by a parallel, 10-d amphipod (Leptocheirus plumulosus) mortality test at 5, 20, and 85 d of equilibration. During the equilibration, AVS increased (up to twofold) with spiked Zn concentration ([Zn]), whereas Zn-simultaneously extracted metals ([SEM]; Zn with AVS) remained relatively constant. Concentrations of Zn in PW decreased most rapidly during the initial 30 d and by 11- to 23-fold during the whole 95-d equilibration period. The apparent partitioning coefficient (Kpw, ratio of [Zn] in SEM to PW) increased by 10- to 20-fold with time and decreased with spiked [Zn] in sediments. The decrease of PW [Zn] could be explained by a combination of changes in AVS and redistribution of Zn into more insoluble phases as the sediment aged. Amphipod mortality decreased significantly with the equilibration time, consistent with decrease in dissolved [Zn]. The median lethal concentration (LC50) value (33 μM) in the second bioassay, conducted after 20 d of equilibration, was twofold the LC50 in the initial bioassay at 5 d of equilibration, probably because of the change of dissolved Zn speciation. Sediment bioassay protocols employing a short equilibration time and high spiked metal concentrations could accentuate partitioning of metals to the dissolved phase and shift the pathway for metal exposure toward the dissolved phase.
Chemometric modeling of main contamination sources in surface waters of Portugal
Authors: Tauler Romá , Lacorte Silvia , Guillamón Miriam , Cespedes Raquel , Viana Paula , Barceló Damia
Published: March 2005

Various chemometric data analysis methods, such as principal components analysis, multivariate curve resolution—alternating least squares, parallel factor analysis, and Tucker3, are proposed and compared for the resolution and modeling of main contamination sources in a large environmental data array obtained in an exhaustive environmental monitoring program that examined the quality of surface waters of Portugal. The study covered the analysis of 19 priority semivolatile organic compounds (SVOCs) frequently found in a total number of 644 surface water samples, including 46 different sites from throughout Portugal and corresponding to a period of 14 months, from April 1999 to May 2000. Main contamination sources of the analyzed SVOCs were identified and interpreted according to their chemical composition and according to their resolved geographical and temporal distribution profiles.
Fish full life-cycle testing for androgen methyltestosterone on medaka (Oryzias latipes)
Authors: Seki Masanori , Yokota Hirofumi , Matsubara Haruki , Maeda Masanobu , Tadokoro Hiroshi , Kobayashi Kunio
Published: March 2005

We studied the chronic effects of methyltestosterone (MT) on reproductive status of medaka (Oryzias latipes) over two generations under continuous exposure to verify the applicability of the fish full life-cycle test (FFLC) for this androgen with this species. The exposure of parental (F0) medaka to MT was begun on embryos within 12 h postfertilization and continued for up to 101 d; assessment endpoints included embryological development, hatching, posthatch survival, growth, sexual differentiation, reproduction, and hepatic vitellogenin (VTG) levels under flow-through exposure to MT at each mean measured concentration of 0.35, 1.09, 3.29, 9.98, and 27.75 ng/L. Eggs (F1) spawned from the F0 fish at 98, 99, and 100 d posthatch were examined for hatchability, survival after hatching, growth, sexual differentiation, and hepatic VTG level until 60 d posthatch. In the FFLC with medaka, MT induced masculinization of both secondary sex characteristics and gonads. We observed that all F0 fish in the 27.75-ng/L treatment group showed male secondary sex characteristics in which no fish with ovary could be discerned. Several fish with ovaries in F0 and F1 generations treated with 9.98 ng/L showed male secondary sex characteristics. We also observed swollen abdomens in the F0 and F1 female fish in the 9.98-ng/L treatment group. These swollen abdomens were induced by enlarged ovaries and were accompanied with declined fecundity and fertility in the F0 generation. These results indicate that MT reduces the reproductive potential of medaka and that the FFLC with this species is applicable to the evaluation of androgens.
Energy-based modeling as a basis for the analysis of reproductive data with the midge (Chironomus riparius)
Authors: Ducrot Virginie , Péry Alexandre R. R. , Mons Raphaël , Garric Jeanne
Published: March 2005

We propose a biologically based approach to analyze reproductive data for the midge (Chironomus riparius). We showed in a previous study that its larval development can be divided in two distinct phases regarding the use of energy: The somatic growth period and the gametic growth period. We hypothesize here the gametic period to be a crucial period for the energetic investment for reproduction. To test this, we performed several assays with different feeding programs. Our results confirmed that energetic investment for reproduction mainly occurs during the gametic growth period. We could then propose energy-based models to analyze reproductive data. We assumed the effects to result from a perturbation in the use of energy. Two models corresponding to different physiological modes of actions—decreased efficiency of feeding (i.e., feeding decrease model) or increased cost of egg production (i.e., egg-cost increase model)—were built and used for the analysis of data obtained after an exposure to an artificially copper-spiked sediment. During this experiment, different exposure patterns were performed to investigate whether effects on reproduction resulted mainly from an exposure that occurs during the gametic growth period or from an exposure that occurs during the somatic growth period. These exposure patterns led to similar effects on reproduction, which suggests that the toxicant-induced stress persists during the whole life cycle, even in case of exposure occurring only during part of it. Both the feeding decrease model and egg-cost increase model were able to describe the data. We showed that addition of copper in the sediment, even in low quantity (<6.5 mg/kg), might affect reproduction at the individual level. If no-effect concentrations were derived from these results, this may lead to an overprotective value. A relevant no-effect concentration could be derived from further investigations at the population level.
Profiles of polychlorinated biphenyl congeners, organochlorine pesticides, and butyltins in southern sea otters and their prey
Authors: Kannan Kurunthachalam , Kajiwara Natsuko , Watanabe Mafumi , Nakata Haruhiko , Thomas Nancy J. , Stephenson Mark , Jessup David A. , Tanabe Shinsuke
Published: March 2005

Concentrations of organochlorine pesticides, polychlorinated biphenyl (PCB)congeners, and butyltins were measured in sea otters and selected prey species (invertebrates) collected from the California (USA) coast. Polychlorinated biphenyls, DDTs (sum of p,p′-dichlorodiphenyldichloroethylene [p,p-DDE], p,p′-dichlorodiphenyldichloroethane [p,p-DDD], andp,p′-DDT), and butyltins were the major contaminants found in sea otters and their prey. Lipid-normalized concentrations of PCBs and DDT in sea otter livers were 60- and 240-fold greater than those found in the prey. Great biomagnification of PCBs and DDT in sea otters is suggested to result from their high per-capita intake of diet compared with those of other marine mammals. Profiles of PCB congeners in sea otters and prey species suggest a great capacity of sea otters to biotransform lower-chlorinated congeners. Sea otters seem to possess a greater ability than cetaceans to metabolize PCBs. The 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of non- and mono-ortho PCBs in sea otters and certain prey species were at or above the theoretical threshold for toxic effects.
Dissipation and effects of chlortetracycline and tylosin in two agricultural soils: A field-scale study in southern Denmark
Authors: Halling-Sørensen Bent , Jacobsen Anne-Marie , Jensen John , SengeløV Gitte , Vaclavik Elvira , Ingerslev Flemming
Published: March 2005

Presently, thereis a basic lack of information concerning the accumulationof antibacterial agent residues in agricultural soils. In this field study, performed in southern Denmark, we assess the dissipation of chlortetracycline (CTC), and tylosin A (TYL A) as a function of time. Field soils were classified as a sandy loam soil (field A) and a sandy soil (field B) and each field was sampled on six occasions during the 155-d experimental period from May to October 2000 for chemical analysis and counts of colony-forming units (CFU) detecting the level of aerobic bacteria surviving antibiotic exposure. Colony-forming units and TYL A were detected throughout the entire sampling period, with respective starting soil concentrations of 30 and 50 μg kg−1 soil declining to 1 and 5 μg kg−1 soil, on day 155. Compound half-lives (95% confidence limits in parentheses) were estimated for both fields and T1/2 for CTC was 25 d (20–34) and 34 d (28–42) in fields A and B, respectively, and T1/2 for TYL A was 67 d (54–86) and 49 d (40–64) in fields A and B, respectively. No significant difference was determined between compound half-lives on the two fields. The level of aerobic antibiotic-resistant bacteria in the soil over time and soil fauna community was assessed in relation to application of manure containing antibacterial agents to the agricultural fields. The level of both CTC- and TYL-resistant bacteria was affected in the soil by amendment of manure, but declined during the study to the same level as observed at the beginning.
Toxicity testing of 16 priority polycyclic aromatic hydrocarbons using Lumistox®
Authors: Loibner Andreas P. , Szolar Oliver H. J. , Braun Rudolf , Hirmann Doris
Published: March 2005

Hazard assessment of industrial sites contaminated with coal tar and its products usually focuses on selected pollutants such as the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by the U.S. Environmental Protection Agency (U.S. EPA). The aim of this study was to investigate to which extent these 16 PAHs contribute to the Vibrio fischeri bioluminescence inhibition measured by the acute Lumistox® luminescent bacteria test. Five of the 16 PAHs—naphthalene(NA), acenaphthylene (ACY), acenaphthene (ACE), fluorene (FLU), and phenanthrene (PHE)—revealed inhibiting effects when measuring saturated aqueous solutions of these compounds. However, in elutriates of PAH-contaminated soils, the amount of leached PAHs was very low, and the 16 PAHs did not considerably contribute to the observed bioluminescence inhibition. Nevertheless, bioluminescence inhibition was higher for elutriates with increased PAH concentration indicating the presence of other toxicants that co-occur with the 16 PAHs. No evidence was observed for increased bioluminescence inhibition due to synergistic effects among PAHs as calculated on the basis of toxic units for an aqueous solution containing all 16 priority PAHs. Data suggest that the U.S. EPA PAHs play only a minor role in causing acute toxicity to V. fischeri when exposed to aqueous elutriates of PAH-contaminated soils.