Pollution-induced community tolerance of freshwater biofilms: measuring heterotrophic tolerance to Pb using an enzymatic toxicity test

This study aims at investigating the impacts of Pb on freshwater biofilms with a pollution-induced community tolerance (PICT) approach using a recently developed short-term toxicity test based on β-glucosidase activity to measure biofilms’ tolerance to Pb. We first investigated more closely the influence of the total suspended solids (TSS) concentrations of biofilm suspensions used for short-term toxicity tests performed to assess Pb tolerance. The Pb EC₅₀ values of four dilutions of the same biofilm suspension increased with their TSS concentrations. TSS-normalization allowed to obtain a unique measure of Pb tolerance, thus confirming that TSS-normalization of EC₅₀ values is a good means to estimate biofilm tolerance to Pb. The experiment was repeated with three different biofilm samples collected at different sites and dates. Second, biofilms were exposed to Pb (0, 1, 10 and 100?μg/L) for 3?weeks in microcosms to assess the impacts of Pb exposure on the communities. An increase in Pb tolerance was observed for the biofilm exposed to 100?μg/L. Automated Ribosomal Intergenic Spacer Analysis revealed modifications of bacterial and eukaryotic community structure with Pb exposure. Moreover, exposure to 100?μg/L Pb also led to an increase in Zn tolerance but not Cu tolerance. This study shows that tolerance acquisition to Pb can be detected after exposure to environmental concentrations of Pb using a PICT methodology and normalized EC₅₀ values as measures of Pb tolerance.     

Low levels of methylmercury induce DNA damage in rats: protective effects of selenium

In this study we examined the possible antigenotoxic effect of selenium (Se) in rats chronically exposed to low levels of methylmercury (MeHg) and the association between glutathione peroxidase (GSH-Px) activity and DNA lesions (via comet assay) in the same exposed animals. Rats were divided into six groups as follows: (Group I) received water; (Group II) received MeHg (100 μg/day); (Group III) received Se (2 mg/L drinking water); (Group IV) received Se (6 mg/L drinking water); (Group V) received MeHg (100 μg/day) and Se (2 mg/L drinking water); (Group VI) received MeHg (100 μg/day) and Se (6 mg/L drinking water). Total treatment time was 100 days. GSH-Px activity was determined spectrophotometrically and DNA damage was determined by comet assay. Mean GSH-Px activity in groups I, II, III, IV, V and VI were, respectively: 40.19 ± 17.21; 23.63 ± 6.04; 42.64 ± 5.70; 38.50 ± 7.15; 34.54 ± 6.18 and 41.39 ± 11.67 nmolNADPH/min/gHb. DNA damage was represented by a mean score from 0 to 300; the results for groups I, II, III, IV, V and VI were, respectively: 6.87 ± 3.27; 124.12 ± 13.74; 10.62 ± 3.81; 13.25 ± 1.76; 86.87 ± 11.95 and 76.25 ± 7.48. There was a significant inhibition of GSH-Px activity in group II compared with group I (P < 0.05). Groups V and VI did not show a difference in enzyme activity compared with groups III and IV, showing the possible protective action of Se. Comet assay presented a significant difference in DNA migration between group II and group I (P < 0.0001). Groups V and VI showed a significant reduction in MeHg-induced genotoxicity (P < 0.001) when compared with group II. A negative correlation (r = −0.559, P < 0.05) was found between GSH-Px activity and DNA lesion, showing that the greater the DNA damage, the lower the GSH-Px activity. Our findings demonstrated the oxidative and genotoxic properties of MeHg, even at low doses. Moreover, Se co-administration reestablished GSH-Px activity and reduced DNA damage.     

Low air levels of benzene: Correlation between biomarkers of exposure and genotoxic effects

This study was aimed to identify useful biomarkers of exposure and effect in workers exposed to low levels of benzene, and to evaluate any correlations existing between these parameters.     

Discharge report for the community pharmacist: Development and validation of a prototype

BackgroundThe potential benefit of community pharmacist's involvement in continuity of care is well-known. However, it is not standard practice to exchange information with the community pharmacist (CP) after hospitalization.ObjectiveTo construct and validate an evidence-based prototype of a discharge report for the community pharmacist.MethodsFirst, a review of literature, guidelines and established initiatives was performed to construct a preliminary discharge report. Secondly, the content of the discharge report was reviewed and optimized using semi-structured individual interviews with CPs and general practitioners (GPs).ResultsThe review identified six guidelines for information exchange with the CP originating from three countries, 17 research papers and three local initiatives. Overall, 49 different elements for a discharge document were identified. Based on recurring elements, a preliminary discharge report was created. Interviews with ten CPs and nine GPs provided insights into which information is considered crucial for patient safety and why. This allowed an optimization of the document. The final discharge report consists of three categories: administrative, medication and medical data. The medication data includes medication registered at hospital admission as well as at hospital discharge, drug indications, reasons for initiating, adjusting or discontinuing therapies and start/stop dates. The medical data contains reasons for hospitalization, comorbidities and allergies.ConclusionsThe literature review and semi-structured interviews resulted in an evidence-based prototype of a discharge report for the community pharmacist. This document contains both administrative, medical and medication data.     

Initial recolonization of benthic fauna in defaunated sediment contaminated with octylphenol: Field microcosm exposure study

Recolonization of benthic fauna in defaunated sediment contaminated with octylphenol (OP) has been investigated by the use ofin situ microcosm exposure study. Trays with defaunated sediment (control) and those treated with five OP concentrations (0.59, 5.4, 7.6, 66, and 660 μg g^?1, sediment dry weight (DW)) were exposed at the subtidal (ca. 10 m), in the southern coast of Korea, over two months. The initial response (after one-month exposure) of macrozoobenthos at the trays of control and three lower OP (0.59–7.6 μg g^?1 DW) showed rapid colonization of macrozoobenthos with high diversity and abundance. However, the species number sharply decreased after two-month exposure, particularly at the tray of greatest OP (660 μg g^?1 DW) treated with species number from 15 (after 30-days) to 3 (after 70-days). Other univariate indices such as abundance and biomass of benthic macrofauna also showed concentration-and time-dependent declines, indicating a potential adverse effect of OP on benthic community recolonization. Further, the multi-dimensional scaling (MDS) analysis that clearly separated two distinct faunal groups of macrobenthos during exposure supported the concentration-dependant recolonization followed by succession at the OP concentration of >7.6 μg g^?1 DW. Similar to macrofauna, the meiofaunal abundance significantly decreased at the OP concentration of >7.6 μg g^?1 DW, indicating certain threshold of OP between 7.6–66 μg g^?1 DW that caused adverse effect on benthic community recolonization. Although the critical adverse OP concentration found in community level was relatively high compared to the environmental concentrations (ppb levels) reported in coastal sediments, it should be pointed out that certain species could be influenced by the exposure of lower OP concentrations.     

Physical dependence and tolerance development after chronic exposure to low levels of morphine in the rat

A sustained-release delivery system containing ¹⁴C-morphine was implanted subcutaneously in rats. Measurement of urinary excretion of ¹⁴C suggested a steady state release of approximately 640 μg ¹⁴C morphine/day during a 10-day test period. Tolerance developed rapidly to the analgetic effects produced by an injected ED₉₅ dose of morphine sulfate in implanted rats tested on the hot-plate. Physical dependence, determined by naloxone-precipitated abstinence behavior, was evident in rats at 24 hr. Morphine dosage was estimated to be as low as 2.5 mg/kg/day. Peak abstinence behavior was observed on Day 4. However, naloxone-precipitated withdrawal signs were markedly diminished by Day 6 and essentially absent by Day 8. These results are discussed with reference to the suggestion that metabolic changes, occuring during chronic exposure to morphine, may explain the lack of abstinence behavior during a time when maximal concentrations of urinary morphine were observed and a high degree of tolerance was manifest.     

Environmental stressors can enhance the development of community tolerance to a toxicant

Ecosystems are subject to a combination of recurring anthropogenic and natural disturbances, such as climate change and pesticide exposure. Biological communities are known to develop tolerance to recurring disturbances due to successive changes at both the community and organismal levels. However, information on how additional stressors may affect the development of such community tolerance is scarce to date. We studied the influence of hydrological disturbance on the reaction of zooplankton communities to repeated insecticide pulses in outdoor microcosms. The communities were exposed to three successive pulses of the insecticide esfenvalerate (0.03, 0.3, and 3 µg/L) and to the gradual removal of water and its subsequent replacement over three cycles or to a constant water level. Except at the highest esfenvalerate concentration, the communities developed tolerance to the toxicant, as indicated by their decreasing reaction to subsequent insecticide applications, and this development was enhanced by hydrological disturbance. The pronounced decline of the key taxa Daphnia spp. through the combined action of the two stressors was identified as the main mechanism responsible for the increase in community tolerance under a fluctuating water level. Under a constant water level, the abundance of Daphnia spp. did not decrease significantly without the insecticide treatment, indicating that other mechanisms were responsible for the observed community tolerance. The present study shows that additional stressors can facilitate the development of community tolerance and that such facilitation is propagated through community-level mechanisms.     

Development and validation of a questionnaire to measure moral distress in community pharmacists

International Journal of Clinical Pharmacy - Background Pharmacists work within a highly-regulated occupational sphere, and are bound by strict legal frameworks and codes of professional conduct....     

Effect of pre- and postnatal exposure to urban air pollution on myocardial lipid peroxidation levels in adult mice

Exposure to air pollution can elicit cardiovascular health effects. Children and unborn fetuses appear to be particularly vulnerable. However, the mechanisms involved in cardiovascular damage are poorly understood. It has been suggested that the oxidative stress generated by air pollution exposure triggers tissue injury. To investigate whether prenatal exposure can enhance oxidative stress in myocardium of adult animals, mice were placed in a clean chamber (CC, filtered urban air) and in a polluted chamber (PC, São Paulo city) during the gestational period and/or for 3?mo after birth, according to 4 protocols: control group—prenatal and postnatal life in CC; prenatal group—prenatal in PC and postnatal life in CC; postnatal group—prenatal in CC and postnatal life in PC; and pre–post group—prenatal and postnatal life in PC. As an indicator of oxidative stress, levels of lipid peroxidation in hearts were measured by malondialdehyde (MDA) quantification and by quantification of the myocardial immunoreactivity for 15-F2t-isoprostane. Ultrastructural studies were performed to detect cellular alterations related to oxidative stress. Concentration of MDA was significantly increased in postnatal (2.45?±?0.84?nmol/mg) and pre–post groups (3.84?±?1.39?nmol/mg) compared to the control group (0.31?±?0.10?nmol/mg) (p?<?.01). MDA values in the pre–post group were significantly increased compared to the prenatal group (0.71?±?0.15?nmol/mg) (p?=?.017). Myocardial isoprostane area fraction in the pre–post group was increased compared to other groups (p?≤?.01). Results show that ambient levels of air pollution elicit cardiac oxidative stress in adult mice, and that gestational exposure may enhance this effect.     

Pre- and postnatal exposure to ambient levels of urban particulate matter (PM2.5) affects mice spermatogenesis

This work characterizes the effects of ambient levels of urban particulate matter (PM_2.5) from the city of Sao Paulo on spermatogenesis using mice exposed during the embryo–fetal and/or postnatal phases of development. Parental generations (BALB/c mice) were exposed to air pollution in chambers with or without filtering PM_2.5 for 4 months. Animals were mated, and half of the 1-day-old offspring were moved between chambers, which yielded prenatal and postnatal groups. Remaining offspring comprised the non-exposed and pre+postnatal exposed groups. After 90 days, the animals were sacrificed for testis collection and weighing. Optical microscopy was used for the morphometric analyses of the cell counts, spermatogenic cycle, proliferation, and apoptosis. Prenatally exposed animals presented reduced body and testicular weight with an increased gonadosomatic index (GSI). Testicular volume also decreased, as well as the tubular diameter in testes of the same animals. Proliferation, apoptosis, and spermatogenic cycle analyses showed no significant differences among groups. However, the tubules at stage VII of pre- and postnatal animals presented a reduced number of elongated spermatids. Pre+postnatal group presented higher spermatid head retention at stages VIII–XII. These results show that ambient levels of PM_2.5 from Sao Paulo city affect spermatogenesis by damaging sperm production.     

Biological monitoring of standardized exposure to ethylbenzene: evaluation of a biological tolerance (BAT) value

The results of standardized 8 h lasting exposures of n=18 volunteers to ethylbenzene (EthBz) at levels of 25 and 100% of the maximum allowable concentrations at the workplace (MAK) value of 100 ppm as well as the results of field studies are considered to evaluate a biological tolerance (BAT) value for EthBz. On the basis of the relationship between the external and internal exposure a BAT value of 1.5 mg/l has been set for the EthBz concentration in blood as the most sensitive and specific parameter of exposure to this aromatic hydrocarbon. The interpretation of EthBz blood values has to take into account the short half-life of t _1/2=0.5 ± 0.08 h in the first hour after the end of exposure in which this aromatic hydrocarbon is eliminated from the blood. The additional determination of the EthBz metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA), respectively, excreted in post shift urine as well as in urine samples at the beginning of the next shift shows good correlations with the external exposure. The biological half-life of MA was calculated to t _1/2=5.3 ± 1.1 h. Because the time of sampling can vary the relationship between the levels of MA to PGA the total concentration of the excreted metabolites depends less on this influence and is therefore better suited for monitoring exposed persons. On the basis of the standardized experiments a BAT value has been proposed of 2 g MA plus PGA corrected per gram creatinine. Both BAT values are adjusted to data which result from earlier standardized exposures during 30 min to EthBz under physical activity of 50 watt on a bicycle ergometer. Received: 10 August 1999 / Accepted: 2 November 1999     

Low levels of the air pollutant 1-nitropyrene induce DNA damage,increased levels of reactive oxygen species and endoplasmic reticulum stress in human endothelial cells

Both epidemiological and experimental studies suggest that exposure to high levels of air pollution is a risk factor associated with cardiovascular disease. Traffic emission is a major source of exposure to persistent air pollutants such as nitrated polycyclic aromatic hydrocarbons (nitro-PAHs). 1-Nitropyrene (1-NP), one of the most abundant nitro-PAHs in diesel exhausts, was selected as a model nitro-PAH for the present study. The aim of the study was to investigate the effects of 1-NP in human umbilical vein endothelial cells (HUVECs) and the metabolic pathways involved. The nitroreductase inhibitor dicoumarol and the coplanar aryl hydrocarbon receptor (AhR) ligand PCB 126 were used to modulate the metabolism of 1-NP. The results revealed that low levels (≤10 μM) of 1-NP induced DNA damage, increased levels of reactive oxygen species (ROS) and increased protein expression of the endoplasmic reticulum (ER) stress chaperone GRP78. A decrease in cell viability was only observed following exposure to a higher level of 1-NP (15 μM). Inhibition of nitroreductive metabolism by dicoumarol attenuated the induction of DNA damage, intracellular ROS levels and GRP78 expression. This suggests that the effects of 1-NP on HUVEC were mediated by metabolites mainly formed at nitroreduction. Our findings suggest that the human blood vessel endothelium is a sensitive target tissue for the major nitro-PAH constituent in diesel exhaust.     

Low levels of sarin affect the EEG in marmoset monkeys: a pilot study

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C.t value (t=5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m(-3), respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood.The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P <0.05) EEG differences. In most vehicle-pretreated marmosets the energy (microV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems.     

Design of a behavioral health program for urban American Indian/Alaska Native youths: a community informed approach

American Indian/Alaska Native (AI/AN) urban youths experience significant mental health and substance use problems. However, culturally relevant treatment approaches that incorporate community perspectives within the urban setting are limited. This study analyzes community perspectives from AI/AN parents, AI/AN youths, and services providers within Los Angeles County. Information gathered was utilized to develop a needs assessment for AI/AN youths with mental health and substance use problems and to design a community-informed treatment approach. Nine focus groups and key informant interviews were conducted. The Los Angeles County community strongly expressed the need for providing urban AI/AN youths with traditional healing services and cultural activities within their treatment program. However, various barriers to accessing mental health and substance abuse treatment services were identified. An integrated treatment approach was subsequently designed as a result of input derived from community perspectives. The community believed that providing urban AI/AN youths with an integrated treatment approach has the potential to decrease the risk of mental health and substance abuse problems in addition to enhancing their cultural identity and self esteem.     

A methodology for estimating human exposure to perfluorooctanoic acid (PFOA): a retrospective exposure assessment of a community (1951-2003)

Perfluorooctanoic acid (PFOA) is a persistent chemical that was recently shown to be widely distributed in the ambient environment. Because of concerns about the possible adverse health effects on persons exposed to PFOA, a retrospective exposure assessment was conducted for a population of about 50,000 persons who reside near one of the facilities where this chemical was used. No similar study of any chemical with the properties of PFOA had ever been performed; thus, several novel methods were developed and applied in this analysis. Historical records of the emissions from the facility were the basis for the estimates of the potential intake of (PFOA) by residents over the past 53 yr. Various well-accepted environmental models were dynamically combined in order to estimate the concentrations in all relevant environmental media including ambient air, surface soil, drinking water, and homegrown vegetables. Following considerable analyses, particulate deposition from facility air emissions to soil and the subsequent transfer of the chemical through the soil was determined to be the most likely source of PFOA that was detected in groundwater. The highest off-site environmental concentrations were predicted to occur about 1 mile away. For this approximately square mile area, during the time period 1951-2003, the model-estimated average air concentration was 0.2 microg/m3, the estimated surface soil concentration was 11 microg/kg, and the estimated drinking water concentration was 4 microg/L. Similar data were generated for 20 additional geographical areas around the facility. Comparison of measured PFOA concentrations in groundwater in the various water districts indicated that the models appeared to overpredict recent groundwater concentrations by a factor of 3 to 5. The predicted historical lifetime and average daily estimates of PFOA intake by persons who lived within 5 miles of the plant over the past 50 yr were about 10,000-fold less than the intake of the chemical not considered as a health risk by an independent panel of scientists who recently studied PFOA.     

Pre- and postnatal exposure to ambient levels of urban particulate matter (PM(2.5)) affects mice spermatogenesis

This work characterizes the effects of ambient levels of urban particulate matter (PM(2.5)) from the city of Sao Paulo on spermatogenesis using mice exposed during the embryo-fetal and/or postnatal phases of development. Parental generations (BALB/c mice) were exposed to air pollution in chambers with or without filtering PM(2.5) for 4 months. Animals were mated, and half of the 1-day-old offspring were moved between chambers, which yielded prenatal and postnatal groups. Remaining offspring comprised the non-exposed and pre+postnatal exposed groups. After 90 days, the animals were sacrificed for testis collection and weighing. Optical microscopy was used for the morphometric analyses of the cell counts, spermatogenic cycle, proliferation, and apoptosis. Prenatally exposed animals presented reduced body and testicular weight with an increased gonadosomatic index (GSI). Testicular volume also decreased, as well as the tubular diameter in testes of the same animals. Proliferation, apoptosis, and spermatogenic cycle analyses showed no significant differences among groups. However, the tubules at stage VII of pre- and postnatal animals presented a reduced number of elongated spermatids. Pre+postnatal group presented higher spermatid head retention at stages VIII-XII. These results show that ambient levels of PM(2.5) from Sao Paulo city affect spermatogenesis by damaging sperm production.