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PubMed2006

Axillary ultrasonography to detect recurrence after sentinel node biopsy in breast cancer.

BACKGROUND: Sentinel node biopsy (SNB) for breast cancer has a false-negative rate of approximately 5%. Initial reports of follow-up show lower axillary recurrence rates than expected. We performed axillary ultrasonography to determine whether occult recurrences could be detected. METHODS: In a community hospital setting, 289 patients who had SNB for breast cancer in a single surgeon's practice underwent axillary examination by the surgeon followed by axillary ultrasonography by a dedicated breast radiologist. Ultrasonography was performed one time from 4 to 79 months (median, 25 months) after surgery. Five patients with suspicious nodes had ultrasound-guided fine-needle aspiration, and one had a core biopsy. RESULTS: No patient had suspicious nodes on clinical examination. Only six patients had ultrasound findings that warranted intervention. Five patients had benign cytological characteristics, and one had a benign core biopsy result. No evidence of axillary recurrence was found in any patient. CONCLUSIONS: Axillary ultrasonography did not detect occult metastases in any patient and is not recommended for routine follow-up after SNB. The lack of ultrasound evidence of metastasis suggests that the recurrence rate is likely to remain low.

Adult↗
PubMed2005

Evaluation of an independent, radiographer-led community diagnostic ultrasound service provided to general practitioners.

BACKGROUND: Health care services traditionally offered in a secondary setting are increasingly being offered in a primary setting. There has been little assessment of quality and efficiency of diagnostic services such as ultrasound delivered in primary settings and no studies have looked at independently provided services. AIMS: To assess the benefits and disadvantages of a radiographer delivered, primary care-based mobile diagnostic ultrasound service by comparing it to an NHS Trust diagnostic ultrasound service. DESIGN: A retrospective, comparative study. SETTING: A primary care area in the West Midlands. METHOD: Random samples of 200 and 193 adult patients who underwent diagnostic ultrasound in 2001/2002 with the community and NHS Trust services respectively, and all GP principals in the area were identified. Patient access (including wait for appointments), patient and GP satisfaction, clinical quality of services, and cost-effectiveness were assessed by postal questionnaires, interviews, review of stored ultrasound images, patient record review and collection of data on unit costs. RESULTS: Mean wait for an appointment was 17.44 (15.85-19.02) and 44.53 days (38.83-50.23) for the community and NHS Trust services respectively. Response rates from the community and hospital patient groups were 52.9 percent and 44.6 percent, respectively. Demographic characteristics of the two groups of respondents did not differ significantly, therefore justifying comparison between the two groups of respondents. High proportions of patients from both services reported time and location of appointment as convenient. Access to secondary care following an abnormal ultrasound was not systematically different for the services. Patients were highly satisfied with both services. GPs were markedly less satisfied with the NHS Trust service compared to the community service. Quality of stored ultrasound images and reports were comparable for the services. Cost per abnormality detected was higher for the community service (107.69 pound sterling compared to 77.35 pound sterling for the NHS Trust service, not statistically significant). CONCLUSION: The community diagnostic ultrasound service offers reduced waiting times compared to the NHS Trust service, and is of comparable quality. This benefit, together with high patient and GP satisfaction levels, may justify the possible reduced cost-effectiveness of the service compared to the NHS Trust service.

Adult↗
PubMed1993

The detection and assessment of the aneugenic potential of environmental chemicals: the European Community Aneuploidy Project.

Within the framework of its' Environment Research and Development Programme, the European Communities (EC) Directorate General (DG) XII has supported a research project aimed at developing and validating assay systems for the detection and evaluation of chemicals capable of inducing numerical chromosome changes such as aneuploidy and polyploidy. A range of test chemicals were selected, which include a core set comprising; colchicine, econazole nitrate, chloral hydrate, hydroquinone, diazepam, thiabendazole, cadmium chloride, thimerosol, pyrimethamine and vinblastine sulphate. These test chemicals were used to evaluate the ability of test systems ranging from tubulin polymerisation, fungal cultures, cultured mammalian cells and intact rodents to detect chemical aneugens and to assess the significance of such activity to exposed human populations.

Aneuploidy↗
PubMed2006

Quantifying the influence of sociality on population structure in bottlenose dolphins.

1. The social structure of a population plays a key role in many aspects of its ecology and biology. It influences its genetic make-up, the way diseases spread through it and the way animals exploit their environment. However, the description of social structure in nonprimate animals is receiving little attention because of the difficulty in abstracting social structure from the description of association patterns between individuals. 2. Here we focus on recently developed analytical techniques that facilitate inference about social structure from association patterns. We apply them to the population of bottlenose dolphins residing along the Scottish east coast, to detect the presence of communities within this population and infer its social structure from the temporal variation in association patterns between individuals. 3. Using network analytical techniques, we show that the population is composed of two social units with restricted interactions. These two units seem to be related to known differences in the ranging pattern of individuals. By examining social structuring at different spatial scales, we confirm that the identification of these two units is the result of genuine social affiliation and is not an artefact of their spatial distribution. 4. We also show that the structure of this fission-fusion society relies principally on short-term casual acquaintances lasting a few days with a smaller proportion of associations lasting several years. These findings highlight how network analyses can be used to detect and understand the forces driving social organization of bottlenose dolphins and other social species.

Animals↗
PubMed2004

Seasonal changes in the sensitivity of river microalgae to atrazine and isoproturon along a contamination gradient.

A study was undertaken to investigate the environmental impact of herbicides on natural communities of freshwater periphyton and phytoplankton in the river Ozanne and in related nearby water reservoirs, including both pristine and pesticide- (atrazine and isoproturon) contaminated stations. The microalgal toxicity of both herbicides was investigated by short-term studies, using the in vivo fluorescence pattern to perform dose-effect experiments. The taxonomic composition of the communities sampled was assessed by microscopy and by HPLC pigment analysis. The EC50 (periphyton) or EC125 (phytoplankton) values, calculated using in vivo fluorescence endpoints, increased with the herbicide concentration found in the water. In contrast, the structure of the algal communities (periphyton) inhabiting the contaminated stations seemed to be permanently affected when compared to the reference community. A 'memory effect' could be detected, both in herbicide sensitivity and in the structure of periphytic communities that persisted even when peak contaminations had disappeared. This study shows that the response of algal communities is likely to reflect past selection pressures, and suggests that the function and structure of a community could both be modified by the persistent or repeated presence of microcontaminants in natural environments. We could use short-term ecotoxicological tests on freshwater microalgae to assess the effects of past temporary contaminations by agricultural pesticides, and combining this with diversity indices could make it possible to assess the ecotoxicological risk of herbicide contamination even when a complete chemical analysis of the contamination is not feasible.

Agriculture↗
PubMed2004

Optimization of diagnostic microarray for application in analysing landfill methanotroph communities under different plant covers.

Landfill sites are responsible for 6-12% of global methane emission. Methanotrophs play a very important role in decreasing landfill site methane emissions. We investigated the methane oxidation capacity and methanotroph diversity in lysimeters simulating landfill sites with different plant vegetations. Methane oxidation rates were 35 g methane m-2 day-1 or higher for planted lysimeters and 18 g methane m-2 day-1 or less for bare soil controls. Best methane oxidation, as displayed by gas depth profiles, was found under a vegetation of grass and alfalfa. Methanotroph communities were analysed at high throughput and resolution using a microbial diagnostic microarray targeting the particulate methane monooxygenase (pmoA) gene of methanotrophs and functionally related bacteria. Members of the genera Methylocystis and Methylocaldum were found to be the dominant members in landfill site simulating lysimeters. Soil bacterial communities in biogas free control lysimeters, which were less abundant in methanotrophs, were dominated by Methylocaldum. Type Ia methanotrophs were found only in the top layers of bare soil lysimeters with relatively high oxygen and low methane concentrations. A competetive advantage of type II methanotrophs over type Ia methanotrophs was indicated under all plant covers investigated. Analysis of average and individual results from parallel samples was used to identify general trends and variations in methanotroph community structures in relation to depth, methane supply and plant cover. The applicability of the technology for the detection of environmental perturbations was proven by an erroneous result, where an unexpected community composition detected with the microarray indicated a potential gas leakage in the lysimeter being investigated.

Base Sequence↗
PubMed2005

Specific detection, isolation, and characterization of selected, previously uncultured members of the freshwater bacterioplankton community.

High-throughput cultivation was combined with rapid and group-specific phylogenetic fingerprinting in order to recover representatives of three freshwater bacterioplankton communities. A total of 570 bacterial cultures were obtained by employing the most probable number and MicroDrop techniques. The majority of the cultured bacteria were closely related to previously uncultured bacteria and grouped with the alpha-Proteobacteria, beta-Proteobacteria, Actinobacteria, Firmicutes, or Flavobacteria-Cytophaga lineage. Correspondingly, the natural bacterioplankton community was analyzed by high-resolution phylogenetic fingerprinting of these five bacterial lineages. 16S rRNA gene fragments were generated for each lineage and subsequently separated by denaturing gradient gel electrophoresis. By the combination of five group-specific PCR protocols, the total number of 16S rRNA gene fingerprints generated from the natural communities was increased sixfold compared to conventional (eubacterial) fingerprinting. Four of the environmental alpha-Proteobacteria 16S rRNA gene sequences obtained from the natural community were found to be identical to those of bacterial isolates. One of these phylotypes was detected in 14 different cultures and hence represented the most frequently cultured bacterium. Three of these 14 strains were characterized in detail. Their complete 16S rRNA gene sequences showed only 93% similarity to that of Sandaracinobacter sibiricus, the closest relative described so far. The novel phylotype of bacterium is a strict aerobe capable of using numerous organic carbon substrates and contains bacteriochlorophyll a bound to two different photosynthetic light-harvesting complexes. Dot blot hybridization revealed that the strains occur in lakes of different trophic status and constitute up to 2% of the microbial community.

Animals↗
PubMed1993

Conjugal gene transfer to aquatic bacteria detected by the generation of a new phenotype.

An experimental approach based on the assembly of genes of a catabolic pathway was used to detect transconjugants in aquatic communities. Resistance to phenylmercury acetate was established in transconjugants when wide-host-range conjugal plasmids containing merB, the gene encoding organomercurial lyase, were transferred to strains from aquatic communities that had been acclimated to inorganic mercury and thus enriched for populations containing merA, the gene encoding mercuric reductase (T. Barkay, Appl. Environ. Microbiol. 53:2725-2732, 1987). Conjugation was confirmed by using the plasmids' encoded antibiotic resistance patterns and by hybridization with a eukaryotic gene. Three merB-conjugal plasmids, belonging to incompatibility groups W (pGTE16), P1 (pGTE26), and N (pGTE25), were prepared. Transfers by filter matings of pGTE16 and pGTE26 from Pseudomonas aeruginosa PA01 to indigenous strains were at efficiencies of 4.5 x 10 and 4.8 x 10 transconjugant per potential recipient, respectively. These efficiencies were from 1 to 2 orders of magnitude below those observed for intraspecies matings with genetically marked recipients. The third plasmid, pGTE25, was not stably maintained in P. aeruginosa donors, and its transfer from Escherichia coli donors was below the level of detection. Characterized transconjugant strains were shown to be Pseudomonas spp. Potential applications of the described experimental approach in the creation of bacterial populations with new catabolic capabilities in hazardous waste sites and in the detection of transfer of recombinant DNA from engineered microorganisms to indigenous bacteria are discussed.

Journal Article↗
PubMed2006

Ecological risk assessment of contaminated soil.

This review has described three cases of ecological risk assessment. The cases include two heavy metals (Cu and Zn) and an anthropogenic organic chemical (DDT). It concludes that there are at least two major constraints hampering the use of laboratory tests to predict effects under natural field conditions. One key issue is bioavailability, and another is suboptimal conditions or multiple stresses in the field such as climatic stress (drought, frost), predators, competition, or food shortage. On the basis of the presented case studies, it was possible to answer three essential questions often raised in connection to ecological risk assessment of contaminated sites. 1. To what extend does soil screening level (SSL) estimate the risk? The SSL are generally derived at levels corresponding to the lowest observed effect levels in laboratory studies, which often is close to the background levels found in many soils. In the cases of zinc and especially DDT, the SSL seemed quite conservative, whereas for copper they resemble the level at which changes in the community structure of soil microarthropods and the plant community have been observed at contaminated sites. The SSL correspond as a whole relatively well with concentrations where no effects or only minor effects were observed in controlled field studies. However, large variation in field surveys can often make it difficult to conclude to what extent the SSL corresponded to no-effect levels in the field. 2. Do bioassays represent a more realistic risk estimate? Here, there is no firm conclusion. The zinc study in UK showed a better relationship between the outcome of ex situ bioassays and field observations than the SSL. The latter overestimated the risk compared to field observations. However, this would be species dependent, as the sensitivity to metals may vary considerably between recognized test species, even within the same group of organisms, such as Folsomia candida and Folsomia fimetaria or Eisenia fetida and Lumbricus sp. Furthermore, it was demonstrated that bioassays were not useful for predicting general species diversity in the field as they are strongly influenced by natural variation and other factors not related to contamination. In the case of copper, bioassays with springtails and black bindweed seemed to underestimate the risk compared to the Cu concentrations at which significant changes in the community structure of soil microarthropods and plants have been observed at the contaminated site, and this was also the case for the DDT-contaminated soils. Here, bioassays with DDT-contaminated soils showed generally very low toxicity, with EC10 values considerably higher than the levels where clear effects on single species as well as community structure have been detected in the present field study. 3. Is it possible to make sound field surveys or do we lack suitable reference situations? Large natural variation caused by other factors than contaminants were observed in most cases, and this may have particularly hampered the conclusions made in the field surveys. These factors included pH, private and military traffic, age of vegetation, shading effects, and variations in light insensitivity as well as quantity and quality of organic matter. It was therefore concluded that field studies should always be interpreted in concert with similar data from a reference situation. Conclusions should therefore be made with caution in situations where important soil conditions vary between control plots and the contaminated sites. The cases also showed that indices focusing on species richness were unreliable. Estimates of evenness or dominance were recommended instead, and most authors concluded that multivariate analysis of community structure was a sensitive and useful method superior to single-species field data. This review concludes that there is a need for a tiered approach in ecological risk assessment of contaminated soils. Generic soil screening levels are needed as a first tier. Higher tiers of ecological risk assessment should, however, contain some kind of site-specific assessment. It is furthermore important to organize the various studies in a framework or decision support system that is transparent and useful for all stakeholders. A weight of evidence approach may be an obvious choice to deal with these uncertainties. The TRIAD approach, which incorporates and categorizes information in a triangle - chemistry, toxicology, and ecology - is an appropriate tool for handling conceptual uncertainties.

Animals↗
PubMed2004

New features of rubella in Spain: the evidence of an outbreak.

In most of western Europe the rubella vaccine coverage is high. However, prior to the introduction of the vaccine in Latin America, rubella susceptibility in women of childbearing age was 10-25%. Forty one (93%) countries in Latin America have adopted the rubella vaccine since 2002. The adult immigrant population in Spain constitutes a group of susceptibles. In February 2003, the Madrid Community Measles Elimination Plan detected an increase in rubella notifications in women who had been born in Latin America. A descriptive study was undertaken to characterise the outbreak. A confirmed case was a person with fever or rash and a positive IgM serology, and living in Madrid, between 1 December 2002 and 31 March 2003. The secondary attack rate (SAR) per household was calculated. A total of 19 cases of rubella were identified, 15 were confirmed and 4 were probable cases. Fourteen (73.7%) cases were women at childbearing age. The mean age was 25.1 years. One pregnancy was diagnosed with a voluntary termination. Eleven (57.9%) cases were from Ecuador. The mean time of residence in Spain was 41 months. None of the cases or the 54 (78.3%) household contacts had been vaccinated against rubella. The SAR was 9.1%. This study showed the spread of rubella in the susceptible Latin American Community that is resident in Madrid. The interventions proposed were a vaccination programme towards immigrants, a health education campaign to prevent congenital rubella, and a health professional training programme case management.

Adolescent↗
PubMed1975

Detection, treatment and follow-up of hypertension in a community sample of 55-year-old men.

In connection with a population study including 703 randomly selected 55-year-old men, 20 men with the highest blood pressure were selected for a careful follow-up and treatment for 1 year. Controls without hypertension were randomly selected from the remainder of the same population. Electrocardiogram at rest and in connection with an exercise test, changes in fundus oculi, orthostatic tests, peripheral arterial blood flow, chemical analyses and other variables were recorded on three occasions during the observation year. Drug treatment was standardized. Basic treatment was induced with polythiazide, which normalized the blood pressure in the majority of the hypertensive cases. The most striking findings in the hypertensive group before treatment were, besides the high blood pressure at rest, high blood pressure during exercise, an increased peripheral blood-flow through the calves, and an increased heart rate. During treatment, the blood pressure were selected for a careful follow-up and blood-flow were almost "normalized"; the heart-rate remained elevated. The investigation shows that it is quite easy to achieve adequate reduction of blood pressure in hypertension among middle-aged men, as found in the "real world" outside the hospital. The main problem today is not to normalize the blood pressure but rather to detect hypertension and to maintain the therapy for several years. Hypertension is considered to be the cardiovascular risk factor that is probably most amenable to preventive approaches to public health.

Anthropometry↗
PubMed2002

Monofilament assessment of neuropathy in a community diabetes clinic.

OBJECTIVE: To compare the detection of diabetic neuropathy using monofilament, cotton wool, pinprick, vibration sense and symptom evaluation. SETTING: The diabetes clinic of a community hospital. METHODS: Two examiners evaluated 89 women with diabetes mellitus (DM) using a 10 g monofilament, cotton wool, pinprick and a 128 Hz tuning fork after completion of a University of Texas subjective peripheral neuropathy verbal questionnaire. RESULTS: Vibration sense was abnormal in either foot in 8% of subjects. Neuropathy as defined by monofilament, cotton wool and pinprick was present in 26%, 3% and 6% of patients respectively. The respective kappa values (kappa) for the comparison between monofilament neuropathy and cotton wool neuropathy, pinprick neuropathy and symptom-defined neuropathy were 0.18, 0.21 and 0.06. The kappa-value comparing monofilament and tuning fork-defined neuropathy was 0.24. There was fair agreement between 10 versus 3 sites (kappa = 0.60). CONCLUSION: More abnormalities were detected using the monofilament compared with cotton wool or pinprick. There was poor concordance between symptoms and clinically detected neuropathy. The ideal number of sites that need to be evaluated is still contentious.

Cross-Sectional Studies↗
PubMed1996

[Spanish research in international pharmacy and pharmacology journals from 1980 to 1989].

BACKGROUND: During the last years, the usefulness and validity of bibliometric analyses in complementing other types of indicators has been put forward. Especially interesting is the performance of this type of studies in the pharmacological area, due to the important medical and economic repercusions of the research in this field. METHODS: Documents of Spanish authors published in international pharmacological journals covered by the database Science Citation Index (1980-1989) were downloaded. Geographical and institutional distribution of the production, main publication journals and the basic or applied character of the research are some of the parameters analysed. The Expected Impact Factor (FIE) is used as an indicator of the potential influence of the research on the international scientific community. RESULTS: An exponential growth was detected for the number of Spanish publications in international journals of Pharmacy & Pharmacology during the period of 1980-1989. Universities were the most productive institutions, followed by hospitals, the Consejo Superior de Investigaciones Científicas, and industry, with only a small activity from private centers. Geographical distribution of production was very irregular, with Madrid, Barcelona and Valencia as the main productive cities. The increase in productivity was associated with a decrease over time in the FIE, although relatively high FIE journals were mainly used. Research in Pharmacy & Pharmacology showed as a mainly basic field, with a more clinical character for hospitals than for the remaining institutions. An increase in collaboration was observed, as supported by the increase in the coauthorship index, number of institutions per document and collaboration rate. CONCLUSIONS: The international visibility of the Spanish pharmacological research showed and important growth during this period. It was mainly a quantitative growth, since a higher impact or potential influence of the Spanish research over the international scientific community was not detected.

Periodicals as Topic↗
PubMedDate not supplied

[Chagas disease: impact of Triatoma infestans control program in Alto del Carmen, Huasco Province, III Region Atacama, Chile].

A control program of Triatoma infestans has been carried out in Alto del Carmen, an endemic chagasic rural county in the III Region, Chile. The program started in 1988 with an attack phase consisting in a masshouse spraying with residual insecticide, followed by an entomological surveillance phase with health education for community participation and vector detection in eventually reinfested houses. A yearly evaluation in 1992, 1993, 1994 and 1995 was carried out in order to determine the effectiveness of vector control activities. In 1992, 24.1% of dwellings was infested, whereas in 1993, 1994 and 1995 the infestation rates were 3.9%, 2.8% and 4.0% respectively. The similar infestation rates found in 1993, 1994 and 1995 suggest passive dispersion of triatomas from areas without surveillance. Additionally, in 1994, 110 (16.0%) out of 688 examined people resulted serologically positive. It is noteworthy that all of the children in the 0-4 year age group--born after the attack phase--resulted serologically negative. This fact may indicate the interruption of vectorial transmission of Chagas' disease in Alto del Carmen county. It is concluded that the control activities performed in the county constitute good strategies to the Nacional Program of Control of T. infestans, but for the success of such a program it is necessary to integrate the efforts of all endemic areas with an active community participation.

Adolescent↗
PubMed2001

Molecular epidemiology of human astrovirus diarrhea among children from a periurban community of Mexico City.

Human astroviruses (HAstVs) were detected in 23 stool samples from 365 diarrhea episodes among 214 children (<18 months old) prospectively monitored for diarrhea in Mexico City. Stool samples were tested by EIA and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. EIA was less sensitive (74%) and equally specific, compared with RT-PCR analysis using type-common primers for HAstV detection. Of 31 HAstV isolates, EIA typed 18 (69%) of 26 EIA-positive samples, and RT-PCR analysis typed 26 (84%) of 31 RT-PCR-positive samples. Phylogenetic analysis of the 3' end of the capsid region (363 nucleotides) confirmed the type assignment by EIA and RT-PCR analysis and determined the type for 5 previously untyped samples. Six HAstV antigenic types cocirculated in the community: HAstV-2 (42%), HAstV-4 (23%), HAstV-3 (13%), HAstV-1 (10%), HAstV-5 (6%), and HAstV-7 (6%). RT-PCR and sequence analysis provided more detailed epidemiology of HAstV in the community than did antigenic detection methods.

Astroviridae Infections↗
PubMed2005

Direct comparison of single-strand conformation polymorphism (SSCP) and denaturing gradient gel electrophoresis (DGGE) to characterize a microbial community on the basis of 16S rRNA gene fragments.

Characterization of microbial communities using single-strand conformation polymorphism (SSCP) was compared with that using denaturing gradient gel electrophoresis (DGGE). This comparison was based on the V3-4 region (Escherichia coli positions: 341-806) of 16S rRNA gene of bacterial or archaeal communities obtained from a methanogenic bioreactor. Significant differences in the bacterial banding profiles were observed while attempting to detect the diversity of the community and its succession during the reactor operation. The SSCP produced a number of sharp bands and differentiated the bacterial community structures to which the DGGE gave an identical pattern. On the other hand, the SSCP and DGGE provided similar succession patterns for archaeal community.

Bacteria↗
PubMed2006

Evidence for environmental contamination in residential neighborhoods surrounding the defense depot of Memphis, Tennessee.

An interdisciplinary environmental assessment team from the Howard University Environmental Justice Partnership (HUEJP) conducted a site visit and assessment of the Defense Depot of Memphis, Tennessee in February of 2000. This depot was built in the late 1940's for storage of numerous chemicals and munitions. As the years progressed, many Memphis citizens have grown to believe that the activities and chemical stockpile located at this site have negatively affected the health environment of their residents. There is anecdotal evidence and documentation of numerous cancers and other illnesses in those local territories, and specifically, at the Memphis Depot site. Currently, this depot is closed and in remediation by the local government. Particularly, citizens of the Rozelle community have started a campaign to investigate any signs of exposure pathways to noted health risks. The HUEJP was contacted and asked to investigate the community concerns. Obliging to the request, we aimed to sample at three drainage sites and a residential site, talk to local citizens, and gain any additional information that would be helpful in relieving anxiety in the Rozelle community. Soil, sediment, and water samples were collected and analyzed for total organic carbon, inorganic anions, and heavy metals. These data show that for the four sites sampled, the highest concentrations of organic compounds and heavy metals were located either within a residential area or in an area with a direct transport pathway to the community. Atomic absorption analysis revealed detectable amounts of cadmium, lead and chromium metals at all sites with direct transport pathways into the residential community, with chromium concentrations being far in excess of the EPA standard limits.

Environmental Pollutants↗
PubMed2002

A risk assessment of pollution: induction of atrazine tolerance in phytoplankton communities in freshwater outdoor mesocosms, using chlorophyll fluorescence as an endpoint.

We investigated the validity and sensitivity of assessments of the induction of atrazine tolerance in freshwater outdoor mesocosmic phytoplankton communities, using the in vivo fluorescence of chlorophyll a as an endpoint, for monitoring ecotoxicology and for risk assessment programs applied to phytoplankton contaminated by photosystem II herbicides. Atrazine inhibits the photosynthetic process, and so the rise in in-vivo fluorescence could be used as a physiological manifestation of acute toxicity. Short-term tests (1 h) were used, in which increasing concentrations of the herbicide were applied to phytoplankton samples taken every two days from the mesocosms, and used to plot dose-response curves. The concentration at which atrazine increased the fluorescence by 25% relative to control samples was used to demonstrate the sensitivity of the phytoplankton, and the values found were compared for samples from different mesocosms (contaminated and non-contaminated). The taxonomic composition of the phytoplankton was also determined. The data showed that chronic exposure (25 days) to 30 microg/L of atrazine significantly increased the apparent tolerance of the phytoplankton to further contamination by the same compound. The use of in vivo fluorescence of chlorophyll a appears to be a reliable and effective parameter for monitoring the effects of atrazine pollution, and detecting the changes in community tolerance driven by pollution selection pressure.

Adaptation, Physiological↗