Biomedical subjects

W Dott

Publications and source records attributed to W Dott.

At least 37 records · Page 2Linked to original sources

PubMed2000

Exposure to airborne fungi, MVOC and mycotoxins in biowaste-handling facilities.

Health impacts due to fungi in indoor air can only be estimated reliably, if both fungal propagules and fungal secondary metabolites are qualified and quantified. In the present study, the fungal species composition in a compost facility is compared to the spectrum of microbial metabolites in the air with regard to the physiological properties of different fungal species. A number of relevant fungi was tested for the production of both volatile and non-volatile metabolites on different substrata. The profiles of mycotoxins and microbial volatile organic compounds (MVOC) turned out to be specific for certain species in pure culture. Consequently, the fungi may have different toxicological health impacts, though information on the relevance of microbial volatiles is still limited.

Air Microbiology↗

PubMed2000

Species-specific profiles of mycotoxins produced in cultures and associated with conidia of airborne fungi derived from biowaste.

The potential to produce mycotoxins and non-volatile secondary metabolites was investigated for approximately 250 freshly isolated fungal strains. Among the eleven most relevant species, viz. Aspergillus flavus, A. fumigatus, A. niger, A. parasiticus, A. versicolor, Emericella nidulans, Paecilomyces variotii, Penicillium brevicompactum, P. clavigerum, P. crustosum, and P. polonicum, a wide range of metabolites partly of toxicological relevance was identified. Several unknown metabolites were found for the less frequent species, which were primarily investigated for chemotaxonomic delimitation from closely related species. The spectra of metabolites in conidial extracts and culture extracts (containing also mycelium and medium) were compared for a limited number of relevant fungi. Some mycotoxins, such as sterigmatocystin in Emericella nidulans, were not present in the conidial extracts, though produced by most strains. Fumigaclavine C, tryptoquivaline, and trypacidin, characteristic for A. fumigatus, were found in conidial extracts, but highly toxic compounds such as gliotoxin and fumitremorgens were not present. Finally, compounds such as cyclopenol, cyclopenin, and penitrem A being characteristic for certain penicillia, were found in conidial extracts and are therefore assumed to occur in native bioaerosols.

Air Microbiology↗

PubMed1999

Ecotoxicological testing with new kinetic Photorhabdus luminescens growth and luminescence inhibition assays in microtitration scale

Miniaturized luminescence and growth inhibition assays in microtitration plates with the terrestric enthomopathogenic nematode symbiont Photorhabdus luminescens (DSMZ 3368T) are presented and compared with standardized tests with Vibrio fischeri (DSMZ 7151/NRRLB-11177) and Pseudomonas putida (DSMZ 50026). Toxicological parameters (EC and G values) of selected reference toxicants (e.g. heavy metals and environmental samples) were obtained at different temperatures and without sodium chloride supplementation. Kinetic data recordings were compared with results of a cuvette test protocol using integral and endpoint calculation. Growth inhibition experiments with reference samples reveal similar or higher sensitivities as for the Vibrio or Pseudomonas spp. The luminescence inhibition assay shows reduced sensitivities to most of the reference samples compared with the V. fischeri standard assay. But G values obtained with other standardized aquatic assay systems with daphnids, algae and growth inhibition assays with V. fischeri and Ps. putida correspond more closely to data observed with Ph. luminescens. The test procedures are easily to perform and to evaluate and seem to be reliable alternatives to the established protocols at low osmolarities. The sample specifity of the toxic responses of the marine and the terrestric strain recommends to employ both assays to determine the toxic potential of environmental samples. This will support to reduce false positive results in future investigations.

Journal Article↗

PubMed1999

Agonistic and antagonistic toxic effects observed with miniaturized growth and luminescence inhibition assays.

Kinetic data recordings with miniaturized growth and luminescence inhibition assays with prokaryotes (Pseudomonas putida and Vibrio fischeri) reveal typical sample and species specific growth and light emission patterns respectively. Growth inhibiting influences, based on toxicokinetic and toxicodynamic sample specificities appeared in each growth phase. Agonistic and antagonistic effects of combinations of heavy metals like Cd2+, Hg2+ and Pb2+ and other compounds were easily recognized after accurate curve discussions. Some of the influences that made it more difficult to evaluate toxicological results only by restriction on EC values (effective concentrations) were investigated. The findings may lead to a more comprehensive interpretation of toxicological data and a presumption on the composition of complex samples in terms of screening investigations. Therefore, the conclusions demonstrate the possibilities and limits of kinetic data recordings in chronic and acute toxicity testing.

Freezing↗

PubMed1999

Mycotoxins of Aspergillus fumigatus in pure culture and in native bioaerosols from compost facilities.

Exposure to secondary metabolites of airborne fungi in waste handling facilities is discussed in regard to potential toxic impacts on human health. The relevance of mycotoxins has been intensely studied in connection with contamination of food and feed. Toxic secondary metabolites are expected to be present in airborne spores, but exposure to mycotoxins in bioaerosols has not been studied sufficiently. Aspergillus fumigatus is one of the most frequent species in the air of compost plants. A wide range of secondary metabolites was found in pure cultures of freshly isolated strains of A. fumigatus. Tryptoquivaline, a compound with tremorgenic properties, and trypacidin, for which no toxic properties are described, were found in native bioaerosols in a compost facility. The highly toxic metabolites gliotoxin and verruculogen were not found in the bioaerosols.

Aerosols↗

PubMed1999

Species-specific production of microbial volatile organic compounds (MVOC) by airborne fungi from a compost facility.

Thirteen airborne fungal species frequently isolated in composting plants were screened for microbial volatile organic compounds (MVOC), i.e., Aspergillus candidus, A. fumigatus, A. versicolor, Emericella nidulans, Paecilomyces variotii, Penicillium brevicompactum, Penicillium clavigerum, Penicillium crustosum, Penicillium cyclopium, Penicillium expansum, Penicillium glabrum, Penicillium verruculosum, and Tritirachium oryzae. Air samples from pure cultures were sorbed on Tenax GR and analyzed by thermal desorption in combination with GC/MS. Various hydrocarbons of different chemical groups and a large number of terpenes were identified. Some compounds such as 3-methyl-1-butanol and 1-octen-3-ol were produced by a number of species, whereas some volatiles were specific for single species. An inventory of microbial metabolites will allow identification of potential health hazards due to an exposure to fungal propagules and metabolites in the workplace. Moreover, species-specific volatiles may serve as marker compounds for the selective detection of fungal species in indoor domestic and working environments.

Air Microbiology↗

PubMed1999

Interdisciplinary clinical assessment of patients with illness attributed to environmental factors.

Patients with health problems attributed to environmental factors such as chemical pollutants and electromagnetic fields often do not present evidence of an environmental aetiology of their symptoms. It has been postulated, that their problems are due to disorders diagnosed by other medical disciplines, especially allergology and psychiatry. Our study was designed to subject these patients to a comprehensive diagnostic program involving several medical disciplines in order to achieve diagnoses appropriate to explain the patients' symptoms. Fifty patients consecutively referred to the department of environmental medicine in the university hospital of Aachen, Germany, were submitted to the following examinations: (i) environmental medicine (history, clinical examination, biological and/or ambient monitoring for environmental agents); (ii) allergological examination (history, clinical examination, skin tests); (iii) psychiatric examination (psychopathological examination, psychometric and neuropsychological testing). In addition, the patients were examined in other hospital departments according to the symptoms presented. The findings were discussed in case conferences attended by the physicians involved in order to achieve individual diagnoses. The numbers of patients to whom diagnoses were given by different medical disciplines are as follows: psychiatry (32 patients), dermatology (4), allergology (2), neurology (2), rheumatology (2), gynaecology (1), haematology (1). The most frequent mental disorders diagnosed by the psychiatrists were somatoform disorders (19), followed by schizophreniform and delusion disorders (7). In spite of extensive diagnostic efforts, patients with health problems attributed to the environment usually do not present sufficient evidence of an environmental aetiology of their symptoms. On the other hand the symptoms often meet the diagnostic criteria of other diseases, especially of mental disorders.

Adult↗

PubMed1999

[Mycotoxins as exposure parameters in bioaerosols of composting sites].

The potential to produce mycotoxins was investigated for freshly isolated strains of airborne fungi. The spectra of metabolites in conidial extracts and culture extracts were compared for some relevant species. Furthermore, their potential to produce mycotoxins on semi-natural media (compost extract agar) supplemented with sucrose, yeast extract, and carboxymethylcellulose in different combinations was investigated. In native bioaerosols in a compost facility (plant 2), tryptoquivaline, a compound with tremorgenic properties, and trypacidin, for which no toxic properties are described, were found. The highly toxic metabolites gliotoxin and verruculogen were not found in the bioaerosols, although they were produced by some strains in pure culture. An inventory of microbial metabolites in addition of fungal propagules has led to a more detailed identification of potential health hazards at the working place. In addition to the pathogenic and allergological relevance, airborne fungi are thus of toxicological concern.

Aerosols↗

PubMed1999

[MVOC of fungi--use as an indicator for exposure level].

The production of microbial volatile organic compounds (MVOC) by fungi derived from biowaste was studied on synthetic agar (YES), compost-extract media (CEA VAR 1-3) and compost. Exposure assessment was carried out in composting facilities and the occurrence of VOC/MVOC was related to the presence of airborne fungi. A number of non-specific MVOC was found at all sampling sites or in each season, some of which showed preferences for certain sampling sites (3-methyl-1-butanol, 3-octanone). They seemed to be correlated with a certain species composition or with microbial activity, and may thus be used to describe a certain state of decomposition. Correlations between single volatiles and certain fungi were found in situ, but these findings did not match with the species-specific volatiles obtained from pure cultures.

Air Pollutants, Occupational↗

PubMed1999

["Microbial air pollutants--methods for detection of endotoxins, mycotoxins and MVOC"].

In the context of microbial emissions from composting facilities the methods for the detection and identification of the groups of substances released, i.e. endotoxins, mycotoxins and Microbial Volatile Compounds (MVOC) are discussed. With the aid of an overview of the different methods employed for the investigation of the single groups of compounds the current state of the art in this field is presented. In conclusion the enormous research needs, especially with regard to the mycotoxins and MVOC, are pointed out.

Air Microbiology↗

PubMed1998

Airborne fungi and their secondary metabolites in working places in a compost facility.

The present study investigates in detail the exposure to airborne fungal spores in working places in compost facilities. The fungal species composition in the air is compared with the spectrum of microbial metabolites with regard to the physiological properties of different fungal species. The results indicate that the spectrum of microbial volatile organic compounds (MVOCs) and the production of mycotoxins can be specific for certain species. In addition to the pathogenic and allergological relevance, the fungi may have different toxicological health impacts.

Air Microbiology↗

PubMed1998

[Airborne molds and their metabolites at workplaces in composting plants].

Airborne fungal contaminants in composting facilities gain more and more importance in regard to health hazards for workers and an emission of spores and microbial metabolites in the environment. Possible health impacts of bioaerosols are widely discussed from both an allergological and a toxicological point of view. The present study investigates in detail the exposure to airborne fungal spores at working places in compost plants. These fungal spores are compared to the spectrum of microbial volatile metabolites with regard to the physiological properties of each fungal species. The results indicate, that the spectrum of microbial volatile organic compounds (MVOC) as well as the production of mycotoxins can be specific for certain species. In addition to the pathogenic and allergological relevance, the fungi may have different toxicological health impacts. However, an evaluation of health effects caused by the great variety of volatile organic compounds remains difficult, since information on their toxicological impact is lacking.

Air Microbiology↗

PubMed1998

[Selenium status and bronchopulmonary dysplasia in premature infants <1,500 g].

Selenium is an essential component of the antioxidant enzyme glutathione peroxidase that protects tissues against oxidative injury by detoxifying peroxides. In preterm infants the risk for selenium deficiency is increased due to insufficient selenium uptake. Low selenium uptake and as a consequence decreased glutathione peroxidase activity may result in an elevated risk for the development of bronchopulmonary dysplasia (BPD). The aim of this prospective study was to investigate the relationship between the selenium status of preterm infants < 1500 g and the incidence of BPD. We determined the selenium plasma levels by means of atomic absorption spectrometry in 34 VLBW infants (mean birth weight 1075 +/- 249 g; mean gestational age 28.6 +/- 2.5 weeks) within the first 5 days of life and later in the age of 4 weeks. The infants received mainly parenteral nutrition and were not specifically supplied with selenium. Postnatally, the selenium plasma level was 34.2 micrograms/l (17.3/50) [median (25/75% quantil)] and dropped after 4 weeks to a median value of 16.1 micrograms/l (5.2/38.4) (p < 0.001). In the infants with BPD (n = 12) the selenium concentration within the first week of life was 45.0 micrograms/l (31.5/55.6) versus 33.2 micrograms/l (20.2/42.4) in the infants without BPD. In the age of 4 weeks of life the median selenium level was not significantly different between the infants with and without BPD - 17.2 micrograms/l (10.3/22.5) versus 14.8 micrograms/l (8.8/22.6).

Bronchopulmonary Dysplasia↗

PubMed1997

Degradation of 4-Chlorophenol via the meta Cleavage Pathway by Comamonas testosteroni JH5.

Comamonas testosteroni JH5 used 4-chlorophenol (4-CP) as its sole source of energy and carbon up to a concentration of 1.8 mM, accompanied by the stoichiometric release of chloride. The degradation of 4-CP mixed with the isomeric 2-CP by resting cells led to the accumulation of 3-chlorocatechol (3-CC), which inactivated the catechol 2,3-dioxygenase. As a result, further 4-CP breakdown was inhibited and 4-CC accumulated as a metabolite. In the crude extract of 4-CP-grown cells, catechol 1,2-dioxygenase and muconate cycloisomerase activities were not detected, whereas the activities of catechol 2,3-dioxygenase, 2-hydroxymuconic semialdehyde dehydrogenase, 2-hydroxymuconic semialdehyde hydrolase, and 2-oxopent-4-enoate hydratase were detected. These enzymes of the meta cleavage pathway showed activity with 4-CC and with 5-chloro-2-hydroxymuconic semialdehyde. The activities of the dioxygenase and semialdehyde dehydrogenase were constitutive. Two key metabolites of the meta cleavage pathway, the meta cleavage product (5-chloro-2-hydroxymuconic semialdehyde) and 5-chloro-2-hydroxymuconic acid, were detected. Thus, our previous postulation that C. testosteroni JH5 uses the meta cleavage pathway for the complete mineralization of 4-CP was confirmed.

Journal Article↗

PubMed1997

[Microbiologic/hygienic evaluation of the risk potential of bacteria from soil and water sources in combination with biotechnologic risks of soil restoration].

Biological cleanup-processes removing contaminations from soil and ground-water can be carried out "ex-situ" or "in situ". The pollutants are mineralized (totally or partly) by microorganisms. The successful application of bioremediation techniques often leads to an increase of aerobic and facultatively anaerobic bacteria in soil and/or groundwater, a fact that triggered discussions about a potential biological risk originating from these microorganisms. In this study the identification results of 10,200 microorganisms isolated from 109 ground-water- and 152 soil-samples of different sites contaminated with mineral oil or chlorinated aromatics are evaluated with respect to a possible biological risks originating from these microorganisms. According to their biological risk potential, 19.2% (1958) of the isolated organisms can be grouped into risk-groups II, that means they they are able o cause human disease but it is unlikely that they are spread to the community and there is effective prophylaxis or treatment available. The majority of isolates (81.8%) are grouped into risk group I, meaning that it is very unlikely that they cause a human disease. All these microorganisms are either adsorbed to the soil-matrix or within a closed system of a water-treatment-plant, so that the risk of infection is very unlikely for healthy individuals (regarding possible pathways of infection). The risk potential in waste-water-treatment-plants is regarded to be significantly higher than in biological soil-cleanup processes, because of the specific origin of the bacteria and the possible formation of aerosols.

Bacteria, Aerobic↗

PubMed1994

Regulation of chloro- and methylphenol degradation in Comamonas testosteroni JH5.

Comamonas testosteroni JH5 was isolated from a mixed bacterial culture enriched on different chloro- and methylphenols. The strain completely mineralized a mixture consisting of 4-chlorophenol (4-CP) and 4-methylphenol (4-MP). During degradation of the mixture, 4-hydroxybenzyl alcohol, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid, and 4-chlorocatechol were detected as short-lived intermediates. Mineralization of 4-CP and that of 4-MP occurred successively and were accompanied by diauxic growth, whereas 4-CP and 2-methylphenol were mineralized simultaneously. It was ascertained that neither a reversible enzyme inhibition nor potential toxic intermediates caused the observed diauxie. Some facts support the hypothesis that the successive degradation of 4-CP and 4-MP is regulated on the level of transcription. C. testosteroni JH5 contained a meta-cleaving enzyme when pregrown on 4-CP and the isomeric monomethylphenols. Inactivation of this enzyme in the presence of 3-chlorocatechol was observed.

Biodegradation, Environmental↗

PubMed1994

[The efficiency of sterilization methods for different soils].

Three different soil types (two sandy materials and one till soil type) were sterilized with 14 different sterilization methods or variations. The cation-exchange capacity and specific surface of the soil samples were chosen as control parameters of physico-chemical modifications in the soils. Incubation of soil samples in the presence of Na-azide and HgCl2, in addition to tyndallization and fractionated heating of soil lead to a significant reduction of microorganisms. UV radiation and alternating freezing and thawing of soil had no influence on the number of microorganisms. The application of mercury-II-chloride did not lead to the expected sterilization, especially with till. A sterilization of soil is possible by using formaldehyde and ethylene oxide gassing, in addition to autoclaving and gamma radiation. No microorganisms could be detected in the soils after application of these sterilization methods. The cation exchange capacity of the soils was only slightly influenced with these methods. The use of gamma radiation seems to be the best method for sterilization of soils.

Bacteria↗

PubMed1993

Polyphosphate-dependent enzymes in some coryneform bacteria isolated from sewage sludge.

Eleven isolates obtained from a laboratory sewage treatment plant, most of them presumptively assigned to the coryneform genera Curtobacterium and Aureobacterium were studied for the presence of intracellular polyphosphates and polyphosphate dependent enzymes. All isolates stored polyphosphates and showed adenylate kinase activities ranging from 64 to 815 mU mg-1. Polyphosphate:AMP phosphotransferase could only be detected in one isolate. Three isolates showed a polyphosphate kinase activity also in minor amounts from 15 to 17 mU mg-1. A polyphosphate dependent NAD or 3-phosphoglycerate kinase could not be detected. Polyphosphate glucokinase activity was measured in cell-free extracts of nine isolates ranging from 2 to 376 mU mg-1. Three isolates showed in addition to the polyphosphate glucokinase, a glucose-6-phosphate-dependent NAD kinase. For the regeneration of NADP from NAD and polyphosphate, this enzyme system may give the isolates a distinct competitive advantage, especially for anabolic processes. The polyphosphate-dependent enzymes reported here may play an additional role in the complex process of 'biological' phosphate removal from wastewater.

Actinomycetales↗