3D simulation as a tool for improving the safety culture during remediation work at Andreeva Bay.

Andreeva Bay in northwest Russia hosts one of the former coastal technical bases of the Northern Fleet. Currently, this base is designated as the Andreeva Bay branch of Northwest Center for Radioactive Waste Management (SevRAO) and is a site of temporary storage (STS) for spent nuclear fuel (SNF) and other radiological waste generated during the operation and decommissioning of nuclear submarines and ships. According to an integrated expert evaluation, this site is the most dangerous nuclear facility in northwest Russia. Environmental rehabilitation of the site is currently in progress and is supported by strong international collaboration. This paper describes how the optimization principle (ALARA) has been adopted during the planning of remediation work at the Andreeva Bay STS and how Russian-Norwegian collaboration greatly contributed to ensuring the development and maintenance of a high level safety culture during this process. More specifically, this paper describes how integration of a system, specifically designed for improving the radiological safety of workers during the remediation work at Andreeva Bay, was developed in Russia. It also outlines the 3D radiological simulation and virtual reality based systems developed in Norway that have greatly facilitated effective implementation of the ALARA principle, through supporting radiological characterisation, work planning and optimization, decision making, communication between teams and with the authorities and training of field operators.

Real-time 3D radiation risk assessment supporting simulation of work in nuclear environments.

This paper describes the latest developments at the Institute for Energy Technology (IFE) in Norway, in the field of real-time 3D (three-dimensional) radiation risk assessment for the support of work simulation in nuclear environments. 3D computer simulation can greatly facilitate efficient work planning, briefing, and training of workers. It can also support communication within and between work teams, and with advisors, regulators, the media and public, at all the stages of a nuclear installation's lifecycle. Furthermore, it is also a beneficial tool for reviewing current work practices in order to identify possible gaps in procedures, as well as to support the updating of international recommendations, dissemination of experience, and education of the current and future generation of workers.IFE has been involved in research and development into the application of 3D computer simulation and virtual reality (VR) technology to support work in radiological environments in the nuclear sector since the mid 1990s. During this process, two significant software tools have been developed, the VRdose system and the Halden Planner, and a number of publications have been produced to contribute to improving the safety culture in the nuclear industry.This paper describes the radiation risk assessment techniques applied in earlier versions of the VRdose system and the Halden Planner, for visualising radiation fields and calculating dose, and presents new developments towards implementing a flexible and up-to-date dosimetric package in these 3D software tools, based on new developments in the field of radiation protection. The latest versions of these 3D tools are capable of more accurate risk estimation, permit more flexibility via a range of user choices, and are applicable to a wider range of irradiation situations than their predecessors.

Cellular burdens and biological effects on tissue level caused by inhaled radon progenies.

In the case of radon exposure, the spatial distribution of deposited radioactive particles is highly inhomogeneous in the central airways. The object of this research is to investigate the consequences of this heterogeneity regarding cellular burdens in the bronchial epithelium and to study the possible biological effects at tissue level. Applying computational fluid and particle dynamics techniques, the deposition distribution of inhaled radon daughters has been determined in a bronchial airway model for 23 min of work in the New Mexico uranium mine corresponding to 0.0129 WLM exposure. A numerical epithelium model based on experimental data has been utilised in order to quantify cellular hits and doses. Finally, a carcinogenesis model considering cell death-induced cell-cycle shortening has been applied to assess the biological responses. Present computations reveal that cellular dose may reach 1.5 Gy, which is several orders of magnitude higher than tissue dose. The results are in agreement with the histological finding that the uneven deposition distribution of radon progenies may lead to inhomogeneous spatial distribution of tumours in the bronchial airways. In addition, at the macroscopic level, the relationship between cancer risk and radiation burden seems to be non-linear.

Characterization of Francisella tularensis strains, comparing their carbon source utilization.

Thirteen Francisella tularensis strains were isolated from 22 seropositive brown hares (Lepus europaeus) originating from different parts of Hungary, and further two from a patas monkey (Erythrocebus patas) and vervet monkey (Chlorocebus aethiops). The isolates were identified as F. tularensis ssp. holarctica on the basis of culture, morphological and biochemical characteristics. The identification was verified by polymerase chain reaction and the sequencing of the partial 16S rRNA gene. Utilization of carbon sources of the 15 F. tularensis strains was characterized with the Biolog system. The system was able to identify the strains already after 4 h of incubation, not only after the standard 24 h. After the analysis and comparison of the metabolic profiles of our strains with the Biolog database, it was concluded that not all carbon sources indicated in the database were utilized by our isolates. The Biolog software fails to distinguish the highly virulent F. tularensis ssp. tularensis and the moderately virulent F. tularensis ssp. holarctica but the Biolog microplates can be manually read to differentiate the two subspecies based on glycerol source utilization. As all the studied strains were unable to use glycerol, they could be identified as F. tularensis ssp. holarctica. The dendrogram based on the metabolic relationship of the strains shows that the isolates are very similar to each other, which correlates with the conservative genetic character of F. tularensis ssp. holarctica.

Simulation of deposition and clearance of inhaled particles in central human airways.

In this study local distributions of deposited inhaled particles such as radon progenies in realistic human airway bifurcation models of bronchial generations one to six are computed for different geometries, inlet flow profiles, flow rates and particle sizes with computational fluid particle dynamics methods. The movement of the mucus layer in the large central human airways is also simulated by computational fluid dynamic techniques. There is experimental evidence that bronchogenic carcinomas mainly originate at the central zone of the large airway bifurcations, where primary hot-spots of deposition have been found. However, current lung deposition models do not take into consideration the inhomogeneity of deposition within the airways. The inhomogeneous movement of the mucus layer may strongly influence the effect of primary deposition. On the basis of our results, both the deposition and the clearance patterns are highly non-uniform, especially in the vicinity of the carinal ridge of the bifurcations.

Modelling carcinogenic effects of low doses of inhaled radon progenies.

In this study, cellular hit probabilities of alpha particles emitted by inhaled radon progenies in sensitive epithelial cell nuclei were simulated at low exposure levels to obtain useful data for the rejection or in support of the linear no-threshold dose-effect hypothesis. In this work, local distributions of deposited inhaled radon progenies in airway bifurcation models were computed at exposure conditions which are characteristic of homes and uranium mines. Then, maximum local deposition enhancement factors, that is, local per average deposition densities, were simulated, and the effects of the inhomogeneity of deposition on hit probabilities were characterised. Our results suggest that in the vicinity of the carinal regions of the central airways the probability of multiple hits can be quite high even at low doses.

Occurrence of metronidazole and imipenem resistance among Bacteroides fragilis group clinical isolates in Hungary.

During the period between 1987 and 1997, various surveillances of the antibiotic resistance of B. fragilis group isolates revealed that practically all the isolates tested were susceptible to imipenem, metronidazole and chloramphenicol; very few isolates (2.5%) exhibited resistance to amoxicillin/clavulanic acid. However, similarly as in some southern European countries, the percentages of the isolates that were resistant to ampicillin, tetracycline and clindamycin were high throughout this period, and the resistance to cefoxitin increased from 6% to 16%. In 2000, isolates with intermediate or high resistance to imipenem and isolates with increased MICs to metronidazole were emerging among the clinical isolates of B. fragilis. The presence of the cfiA gene was demonstrated by PCR in 7 of 242 isolates (2.9%); 2 of them with high MICs to carbapenems harboured the IS942 element immediately upstream of the resistance genes. In the 2 B. fragilis isolates with increased MICs to metronidazole, the nim gene could be detected by PCR. The IS1186 element was found in these isolates upregulating the metronidazole resistance gene.

Inhibition of microflora associated with oral malignancy.

Changes in the microflora on oral carcinoma surfaces may lead to both local and systemic infections, which may complicate the morbidity of the patient suffering from oral malignant neoplasms. Thus, anticancer therapy, irradiation, chemotherapy or surgery impairs the defence mechanism of the oral mucosa and is accompanied by proliferation of the mucosal biofilm with overgrowth of yeast and bacteria. This study investigates the inhibition of the biofilm present on the surface of oral squamous cell carcinomas. Biofilm samples were obtained from the central surface (1 cm2) of each lesion in 10 patients (eight male, two female; mean age: 47.6 years; SD +/- 7.6) before any antibiotherapy or tumour treatment. Patients were randomly divided into two groups and were rinsed with Meridol mouthrinse (amine fluoride) or placebo (saline solution) for 7 days. Samples were repeatedly taken from the same site after rinsing. Samples were transported in pre-reduced brain heart infusion broth and cultured within 1 h of removal, using aerobic and anaerobic complete and selective media. Total aerobic and anaerobic counts were determined and isolated bacteria were identified. The median counts of colony forming units (CFU/ml) after rinsing with Meridol were significantly lower for both aerobes and anaerobes than before rinsing with Meridol. (For aerobes before rinsing: 1.35 x 10(6), after rinsing: 7.55 x 10(5); p = 0.025; for anaerobes before rinsing: 1.39 x 10(6), after rinsing: 7.15 x 10(5); p = 0.011. Rinsing with placebo: no significant difference was found. Aerobe median counts before rinsing: 1.17 x 10(6), after rinsing: 1.03 x 10(5), and for anaerobes: before rinsing 1.75 x 10(6), after rinsing: 1.51 x 10(6); p > 0.05 [Wilcoxon test].) It was concluded that 7-days (three times a day) Meridol rinsing significantly reduced the surface biofilm of oral carcinoma compared to rinsing with placebo. Clinical examination indicated no irritation of the mucosa. The mouthrinse was well tolerated by the patients, who commented on a reduction in burning sensation and bad breath. Besides routine oral hygiene, rinsing itself could reduce patient morbidity. The findings of the present study indicate that in addition to any other oral focus, the lesion itself, when ulcerated, should receive direct antimicrobial treatment so as to reduce patient morbidity and enhance quality of life.

Prevalence of the carbapenemase gene (cfiA) among clinical and normal flora isolates of Bacteroides species in Hungary.

The carbapenemase gene (cfiA) was detected in 4 (5.7%) of 70 clinical isolates of Bacteroides fragilis from different parts of Hungary. Among 24 other Bacteroides species isolated from infectious processes or from normal faecal flora, none was cfiA-positive. The MIC of imipenem and meropenem for all cfiA-positive B. fragilis isolates was < or =0.25 mg/L, but 17% of the B. fragilis and 46% of the non-fragilis Bacteroides isolates exhibited reduced susceptibility to imipenem (MICs 0.5-2 mg/L). Only one of these isolates produced increased levels of beta-lactamase. No difference was observed in the outer-membrane proteins of B. fragilis isolates that harboured the cfiA gene and those with reduced susceptibility to imipenem.

Evaluation of the Etest for susceptibility testing of Mycoplasma hominis and Ureaplasma urealyticum.

The Etest was used for antibiotic susceptibility testing of Mycoplasma hominis and Ureaplasma urealyticum isolates and the results were compared with those obtained with the broth microdilution method. For 50 clinical isolates of M. hominis the MICs of doxycycline, ofloxacin and ciprofloxacin agreed within +/- one dilution and +/- two dilutions in 82-98% and 98-100% of cases, respectively. The MICs of erythromycin, azithromycin, doxycycline, ofloxacin and ciprofloxacin were evaluated for 50 clinical isolates of U. urealyticum. The corresponding levels of agreement were 70-98% and 94-100%, respectively. Reference isolates M. hominis PG-21 and U. urealyticum T-960 were also used. The Etest seems to be an alternative method for determination of MICs of antibiotics with M. hominis and U. urealyticum.

[Bacterial flora of odontogenic and non-odontogenic inflammations of the oro-facial region]. / Orofaciális tájék odontogén és non odontogén gyulladásainak baktériumflórája.

Samples were collected from 34 patients after extraoral incision in case of infections of oro-facial region (29 odontogen and 5 non odontogen). The authors examined the prevalence, ration and susceptibility of the isolated bacteria to antibiotics. The 98-100% of the bacteria has found were sensitive to Clindamycin and Amoxicillin/Clavulan acid. These antibiotics could be the first choice to treat the above mentioned diseases.

Characterisation of a 5.5-kb cryptic plasmid present in different isolates of Bacteroides spp. originating from Hungary.

The plasmid profiles of 97 Bacteroides isolates collected during screening for different pathogenic markers of this genus were investigated. In all, 48% of 69 isolates from infections that belonged to six species harboured low mol.wt plasmids (2.8-11.0 kb). Similar plasmids were also found in 39% of 28 isolates, belonging to eight species, from faeces of healthy persons. The two most frequently obtained types were the 5.5- and the 4.2-kb plasmids, which were present in 70% and 52% of all plasmid-bearing isolates, respectively. Restriction endonuclease analysis revealed that the 5.5-kb plasmids found in the different Bacteroides spp. exhibited the same restriction map, with the exception that pBVP61 lacked the PstI recognition site. The two plasmid types (4.2 and 5.5 kb) seem to be most widely distributed among Bacteroides isolates independent of the site of isolation and with some differences depending on geographic regions.

The microflora associated with human oral carcinomas.

Both local and systemic infections may complicate the morbidity of patients with oral malignant neoplasms, particularly those presenting intraorally. This study investigated the microbial contents of the biofilms present on the surfaces of oral squamous cell carcinomas. Biofilm samples were obtained from the central surface of the lesions in 21 patients (20 male, 1 female) aged 52.8 (+/- 8.2) years, and from contiguous healthy mucosa, before any antibiotic therapy or any tumour treatment. All lesions were keratinising squamous cell carcinomas with surface ulceration. Samples were transported in reduced brain heart infusion (BHI) broth and cultured within 1 h of removal, using aerobic and anaerobic complete and selective media. The median number of anaerobic colony forming units (CFU/ml) at the tumour sites (1.6 x 10(8)) was significantly higher than for the healthy (control) mucosa (3.0 x 10(7); P = 0.0001, Wilcoxon); the same was true for aerobes at the tumour sites (1.51 x 10(8)) relative to the controls (2.8 x 10(7); P = 0.0008, Wilcoxon). The species isolated in increased numbers at tumour sites were Veillonella, Fusobacterium, Prevotella, Porphyromonas, Actinomyces and Clostridium (anaerobes), and Haemophilus, Enterobacteriaceae and Streptococcus spp. (aerobes). Candida albicans was found at eight of the 21 tumour sites, but never at control sites. It was concluded that human oral carcinoma surface biofilms harbour significantly increased numbers of aerobes and anaerobes as compared with the healthy mucosal surface of the same patient. Candida albicans can also be present in these biofilms. These findings must be considered in relation to the known predisposition of such patients to systemic infections, and to the unpleasant complications of oral morbidity due to infected lesions.

[Microbial study of the surface of malignant tumors of the oral cavity]. / Rosszindulatú szájüregi daganatfelszínek mikrobiológiai vizsgálata.

Malodour and other infection sequelae may increase the morbidity, compromise the oral well-being of the patient suffering from maxillo-facial neoplasia. The purpose of our study was to evaluate the differences of the oral bacterial flora attached to the tumor and the contra lateral sound surfaces. Swabs were obtained and samples were microbiologically cultured. It was concluded, that carcinoma surface biofilm harbors increased levels of both aerobs and anaerobs.

The possible role of anaerobic bacteria in chronic prostatitis.

Prostatis, the most common urological disease in men, afflicts between 25 and 50% of all adult men. Four clinical categories are recognized: acute and chronic bacterial prostatitis, non-bacterial prostatitis and prostatodynia. The role of Gram-positive aerobic bacteria and the different anaerobes in chronic bacterial prostatitis is still a matter of debate. During this study, the urethral discharge and the prostatic fluid obtained after prostatic massage of 50 patients with chronic prostatitis, confirmed by clinical examination and resistant to empirical quinolone therapy, were cultured under aerobic and anaerobic conditions. The parallel specimens from 24 patients exhibited high colony counts of Gram-positive and Gram-negative anaerobic bacteria, either alone (18 cases) or in combination with aerobic bacteria (6 cases). The specimens obtained after prostatic massage of the remaining 26 patients were completely negative for both aerobic and anaerobic bacteria. No Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum or Trichomonas vaginalis were isolated from these patients. Patients with chronic prostatitis who gave positive culture results for anaerobes were treated with amoxicillin/clavulanic acid or clindamycin for 3-6 weeks. After treatment, samples were again taken and cultured for all pathogens known to cause prostatitis. These post-therapeutic samples revealed a decrease or total elimination of the symptoms, and no anaerobic bacteria could be detected.

Induction of release of tumor necrosis factor and IL-6 from human mononuclear cells by Bacteroides strains.

The role of anaerobic Gram-negative bacteria in inducing cytokines during mixed infections involving aerobic and anaerobic bacteria is relatively poorly defined. The purpose of this study was to establish whether or not intact Bacteroides fragilis and related species, isolated from severe infections and from the faeces of healthy persons are capable of releasing tumor necrosis factor (TNF) and IL-6 from human mononuclear cells and whole blood. The purified lipopolysaccharides of Bacteroides fragilis strain (No. 7), extracted by the aqueous phenol method from BHI cultures and from BHI culture supplemented with 5% horse serum, were also tested. TNF release was detected by the WEHI 164-dependent bioassay and IL-6 production by the B-9 cell-dependent bioassay. Heat-inactivated Bacteroides strains belonging to different species were able to induce TNF (1x10(1)-5x10(2) U/mL) and IL-6 (1x10(1)-5x10(5) pg/mL) release from human mononuclear cells. When whole blood was used, the production of TNF and IL-6 was more pronounced (very probably because of the presence of certain serum factors). The culturing conditions (the presence of 5% horse serum in the BHI broth) influenced the inducing activity of almost all strains tested. The isolated lipopolysaccharide of Bacteroides fragilis strain No. 7 proved to have a rough profile on PAGE. There were no differences in TNF and IL-6 induction when the lipopolysaccharides of the strain was cultured in BHI or in BHI supplemented with 5% horse serum. Bacteroides strains often outnumber Enterobacteriaceae in the faeces and in mixed infections, and their role in inducing and/or modulating the host response in septic shock should not be overlooked.

Enterotoxigenic Bacteroides fragilis in Hungary.

Bacteroides fragilis, which constitutes about 1% of the colonic microflora in humans, is the most frequent anaerobic species involved in abscesses, soft-tissue infections and bacteraemias. Additionally, enterotoxigenic strains of B. fragilis have been demonstrated to be associated with diarrhoea in domestic animals and humans. Enterotoxigenic strains of B. fragilis derived from stool specimens and from infectious processes produce a toxin which induces a cytotoxic response in HT-29 colon carcinoma cells. These findings prompted us to investigate the prevalence of enterotoxigenic strains of B. fragilis isolated from various clinical specimens in Hungary. A total of 134 strains were collected from different clinical settings: 74 from infectious processes, 20 from stools of healthy subjects and 40 from the faeces of patients with diarrhoea where no other enteric pathogen could be isolated. Cell culture assays with HT-29 cells were performed on the filtered culture supernatants of the isolated strains. Of the 134 strains, 34 (25.3%) proved toxin-positive. The presence of free toxin was also observed in 20 of 50 (40%) of the faeces of adults with diarrhoea.

Binding of extracellular matrix proteins to the surface of Bacteroides spp.

The binding of fibronectin an vitronectin to 207 Bacteroides strains and the binding of collagen and sialoproteins to 55 Bacteroides strains were investigated by means of latex agglutination tests. The binding of fibronectin, collagen and lactoferrin to the same 55 strains was also tested by using 125I-labelled proteins. The 207 strains, belonging to ten Bacteroides species, were isolated from different infections (51%) and from faeces of healthy subjects (49%). Most of the strains displaying fibronectin binding belonged in the species B. fragilis or B. vulgatus. The binding could be inhibited by preincubation of the cells with an excess amount of fibronectin. No inhibition of the binding was observed with carbohydrates. The vitronectin binding of the strains was less common, but was always observed to accompany fibronectin binding. None of the examined 55 strains exhibited any binding to fetuin or asialofetuin. The radiolabelling method indicated a low binding to 125I-fibronectin. The binding of 125I-collagen-I and 125I-lactoferrin in the Bacteroides strains tested was higher than that of 125I-fibronectin.

Binding of extracellular matrix proteins to the surface of anaerobic bacteria.

The binding of fibronectin, vitronectin, collagen and sialoprotein to 65 anaerobic strains was investigated by means of latex agglutination tests. The binding of fibronectin, collagen and lactoferrin to the same strains was also tested by means of 125I-labelled proteins. The strains were isolated from abdominal infections (55%), from the faeces of healthy subjects (29%) or from the depths of tonsils removed at tonsillectomy (16%). The binding of fibronectin and collagen to Bacteroides fragilis strains, tested by the latex agglutination assay, was stronger than their binding to other species. The vitronectin binding of the strains was less common, but was always accompanied by fibronectin binding. Binding to fibronectin-coated beads was inhibited by pre-incubation of the bacterial cells with soluble fibronectin and by heat or protease treatment of the bacterial suspension. No inhibition of the binding was observed with carbohydrates. None of the 65 strains exhibited any binding to fetuin or asialofetuin; 8% of the strains had a binding site for mucin. The binding to mucin-coated beads was inhibited by pre-incubation of the cells with mucin. The radiolabelling method indicated a low binding to 125I-fibronectin. The binding of 125I-collagen-I and 125I-lactoferrin was higher for the anaerobic strains tested.