Biomedical subjects
Publications and source records attributed to A Nevalainen.
We studied the risk of homicidal behaviour among persons convicted of homicide using an epidemiological method. The results showed that male homicide offenders are at least 10 times more likely to commit a homicide when compared with general male population. This odds ratio was about 150-fold among offenders who had committed at least four previous aggravated violent crimes as well as homicide.
Changes in the levels of free intracellular calcium ([Ca2+]i) and the production of reactive oxygen metabolites (ROM) induced by opsonized indoor air fungi and bacteria in human polymorphonuclear leukocytes (PMNL) were measured. Moreover, modification of a chemotactic peptide (fMLP)-and a tumor promoter (PMA)-induced production of ROM by opsonized fungi and bacteria were studied. The cells were exposed to graded doses of opsonized Candida sp., Aspergillus sp., Cladosporium sp., Stachybotrys sp., Penicillium sp., Paecilomyces sp., or A4 or A91 Streptomyces sp. alone, or together with fMLP or PMA. All the organisms were isolated from air samples of mold-problem buildings. None of the fungi or bacteria induced changes in [Ca2+]i or the production of ROM without opsonization with human serum. Of all opsonized fungi and bacteria, only Candida sp. elevated [Ca2+]i. All fungi and bacteria, except Paecilomyces sp. and Stachybotrys sp., markedly increased the production of ROM in PMNL. Furthermore, A91 Streptomyces sp. and Aspergillus sp. amplified fMLP-induced production of ROM. Only Candida sp. increased PMA-induced phenomen that normally occurs in the lung, was required for biological activity of the fungi and bacteria. Amplification by opsonization of fungi- or bacteria-induced leukocyte activation revealed remarkable changes between these biologically active particles. The present results suggest that many indoor air fungi and bacteria may activate leukocytes to produce oxidative stress, perhaps associated with harmful effects in exposed individuals.
A study of sewage workers' exposure to airborne culturable bacteria and inhaled endotoxins was performed at nine waste-water treatment plants that treat mainly industrial effluents. Airborne endotoxins were collected on glass fiber filters and analyzed using a chromogenic limulus assay. Endotoxin concentrations measured in the immediate vicinity of the waste-water treatment process varied from 0.1 to 350 ng/m3. The eight-hour time weighted average concentrations of endotoxin to which workers were exposed exceeded the suggested exposure limit (30 ng/m3 endotoxin) at four of the plants. Air samples of culturable bacteria concentrations varied between 10 and 10(5) colony-forming units/m3. Of the particles carrying culturable bacteria, 88% had an aerodynamic diameter of less than 4.7 microns. The most common genera of airborne gram-negative bacteria were acinetobacter, citrobacter, enterobacter, klebsiella, and pseudomonas. High levels of exposure to bacteria and bacterial endotoxin usually were related to certain phases of the treatment process. The microbiological contamination of air was highest near the inlets where incoming wastewater entered the basins, in the sludge treatment area, and inside the biofilter tower. In these spaces it is necessary to control and reduce exposure to airborne bacteria and endotoxin at wastewater plants.
The relationship between bacterial counts and endotoxin concentrations in air samples was studied. Selective EMB medium favored the growth of a larger portion of airborne gram-negative bacteria than LES Endo or MacConkey medium and was a good predictor of the endotoxin levels determined with a chromogenic Limulus assay of the air of wastewater treatment plants. The bacterial counts determined with nonselective media correlated poorly with airborne endotoxin levels; however, R2A medium yielded higher viable bacterial counts than TYG medium. Direct counting by epifluorescence microscopy yielded the highest bacterial counts, but no correlation was obtained between total bacterial counts and endotoxin concentrations.
Ammonia, methane, hydrogen sulphide and methyl mercaptides were analyzed in the atmospheres of 16 Finnish municipal waste water treatment plants and in 18 pumping stations. The sulphides were analyzed on site as it was found that, with the standard 0.5-l laminated plastic bags, significant amounts of the vapours were lost from the gas phase. The relative humidity of the sampled air was the most likely cause. Under normal operating conditions, sulphides varied from less than 0.07 to 53 micrograms l-1, with highest concentrations found at the sludge presses. Pumping stations had sulphide vapours from 0.07 to 0.5 microgram l-1. The presence of ammonia (0.007-3.5 micrograms l-1) and methane (0.7-18 micrograms l-1) confirmed the hypothesis of the anaerobic origin of the offensive gases. Although more effective ventilation without scrubbing the emission gases would reduce the health hazard in the plants it would burden the environment.
Dampness and mold growth in buildings cause spore generation into indoor air, which is associated with respiratory tract disorders. Specific agents or cellular mechanisms of diseases have not yet been identified. In this study, airborne spores of Streptomyces sp., isolated from moldy houses, stimulated RAW264.7 macrophages, which produced tumor necrosis factor alpha and interleukin-6 and induced the expression of inducible nitric oxide synthase, with subsequent nitric oxide production. Spores of other microorganisms typically found in moldy houses did not markedly increase the production of these inflammatory mediators. The data implied a mechanism by which Streptomyces sp. may lead to respiratory tract disorders in individuals who live in moldy houses.