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Biomedical subjects

E Vilalta

Publications and source records attributed to E Vilalta.

6 recordsLinked to original sources
PubMed2004

Nuisance odours produced by benthic cyanobacteria in a Mediterranean river.

Geosmin dynamics in the Llobregat waters were related to the waxing and waning of benthic cyanobacterial mats developing in the river. Geosmin concentration in the water during 2002 reached a maximum of 204 ng L(-1), and coincided with an abundance of cyanobacteria in the river. Cyanobacterial mats were favoured by the high nutrient content of the waters. The cyanobacterial mats experienced a process of growth in thickness (attached forms), until they became unattached and drifted downstream (free-floating forms), accumulating in shallow areas of the river. Geosmin in the biofilm ranged from 0.55 +/- 0.97 ng geosmin per mg DW(-1) in the attached biofilms and 5.25 +/- 4.96 ng geosmin per mg DW(-1) in the free-floating biofilms. While the attached mats could be responsible for the local occurrence of geosmin at a given site, the free-floating mats became a relevant agent for the dispersion of the metabolite downstream. This impression was reinforced by the extremely high correlation between the geosmin content in the free-floating biofilm and in the water (r = 0.917, p = 0.00001). In order to reduce the geosmin concentration and accumulation of the cyanobacterial mats in shallow river waters, the nutrient content should be controlled and the natural flow conditions restored, to prevent the growth and accumulation of the geosmin-producing cyanobacterial mats.

Cyanobacteria↗
PubMed2004

Geosmin occurrence in riverine cyanobacterial mats: is it causing a significant health hazard?

Toxicity endpoints (nonspecific cytotoxicity, hepatotoxicity, neurotoxicity, immunotoxicity, and mutagenicity) were studied in cyanobacterial mats obtained from a shallow river. Some of the cyanobacterial mats tested were known to be non-geosmin producers, while others were geosmin-producers. No microcystin-like compounds were detected by HPLC in any of the biofilm samples. The mutagenicity and neurotoxicity of biofilm metabolites was negligible, and generally weak adverse effects of biofilm extracts detected in a battery of in-vitro assays indicated relatively low human health risks associated with biofilm toxicity. While the toxicity responses detected in the studied biofilms were weak, effects were not related to production of geosmin. It was therefore concluded that the production of this metabolite cannot be taken as an indication per se of the existence of a health hazard.

Animals↗
PubMed2003

Biofilm structure and function and possible implications for riverine DOC dynamics.

Biofilms are major sites of carbon cycling in streams and rivers. Here we elucidate the relationship between biofilm structure and function and river DOC dynamics. Metabolism (extracellular enzymatic activity) and structure (algae, bacteria, C/N content) of light-grown (in an open channel) and dark-grown (in a dark pipe) biofilms were studied over a year, and variations in dissolved organic carbon (DOC) and biodegradable DOC (BDOC) were also recorded. A laboratory experiment on 14C-glucose uptake and DOC dynamics was also performed by incubating natural biofilms in microcosms. On the basis of our field (annual DOC budget) and laboratory results, we conclude that light-grown biofilm is, on annual average, a net DOC consumer. This biofilm showed a high monthly variability in DOC uptake/release rates, but, on average, the annual uptake rate was greater than that of the dark-grown biofilm. The higher algal biomass and greater structure of the light-grown biofilm may enhance the development of the bacterial community (bacterial biomass and activity) and microbial heterotrophic activity. In addition, the light-grown biofilm may promote abiotic adsorption because of the development of a polysaccharide matrix. In contrast, the dark-grown biofilm is highly dependent on the amount and quality of organic matter that enters the system and is more efficient in the uptake of labile molecules (higher 14C-glucose uptake rate per mgC). The positive relationships between the extracellular enzymatic activity of biofilm and DOC and BDOC content in flowing water indicate that biofilm metabolism contributes to DOC dynamics in fluvial systems. Our results show that short-term fluvial DOC dynamics is mainly due to the use and recycling of the more labile molecules. At the river ecosystem level, the potential surface area for biofilm formation and the quantity and quality of available organic carbon might determine the effects of biofilm function on DOC dynamics.

Analysis of Variance↗
PubMed1995

[Ancylostomiasis and strongyloidiasis: clinico-epidemiologic comparative study of travelers coming from endemic areas].

BACKGROUND: The increase in immigration and adventure travelling by tourists generates a population susceptible to have a type of helminthiasis which we are not familiar with. The clinical-epidemiologic characteristics of different groups of patients with this disease are presented. METHODS: A descriptive retrospective longitudinal study was carried out. The clinical-epidemiologic and imaging laboratory data of 56 patients with ankylostomiasis and strongyloidiasis observed in the Department of Tropical Medicine of the Hospital Clinic i Provincial, in Barcelona, Spain, were collected. RESULTS: Ankylostomiasis and strongyloidiasis represent 2% of the global diseases attended. The risk factor the "use of open footwear" was present in almost all the cases. Among the immigrants this parasitosis may become manifest up to 10 years after the last contact. The digestive form and the accidental finding were the most common forms of presentation among the tourists and immigrants, respectively, with diarrhoea being the most frequent manifestation among the tourists (p = 0.008). Forty-five percent of the patients presented polyparasitism, being more frequently observed among the immigrants (p = 0.025). Anemia was found among 44% of the immigrants while this was not observed in any of the tourists (p = 0.012). No clinical relapse was observed with treatment with mebendazol and thiabendazol. CONCLUSIONS: A clinically different behavior was observed between the two groups of travellers. Although infrequent, the clinical importance ot its diagnosis is based on avoiding severe complications in immunosuppressed individuals and preventing anemia in patients with several diseases.

Adult↗