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H Rüden

Publications and source records attributed to H Rüden.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Use of UV radiation for the disinfection of water. V. Microbiological studies of the behavior of bacterial cells from the logarithmic and from the stationary phase in cold and warm drinking water].

The u.v.-susceptibility of E. cloacae, E. coli and E. faecium was tested with a flow-through u.v. light treatment apparatus. Drinking water of three ranges of temperature (ca. 13 degrees C, ca. 33 degrees C, and ca. 48 degrees C) was used. The u.v.-susceptibility was tested with bacteria harvested in the exponential phase of growth as well as with bacteria harvested in the stationary phase. In all ranges of temperature and both phases of growth reductions of at least 99.9999% of E. cloacae and E. coli were obtained by a dosage of less than or equal to 25 mWs/cm2. For E. faecium harvested in the exponential phase of growth this could be confirmed in cold water of 13 degrees C, while in warm water of 48 degrees C a dosage of ca. 47 mWs/cm2 for a reduction of 99.9999% was necessary. To kill E. faecium-cells, which were harvested in the stationary phase, dosage between 39 and 45 mWs/cm2 were necessary in water of the three ranges of temperature.

Bacteria↗
PubMed1990

[Chemical and biological characterization of electrofilter dust from a waste incinerating plant. 2. Mutagenic activity of organic extracts and their subfractions and determination of the PAH content].

In a recent study, we showed that the Soxhlet extraction with toluene and pretreatment with diluted HCl is the best suitable method to remove organic compounds from particles collected by electrostatic precipitation in municipal waste incinerators. In the present paper, the mutagenic activity of the extracts from particulate samples were studied, using strain TA 100 as a tester strain. A small if any mutagenic activity was observed from most of the samples. The highest mutagenic effects were observed at different extract concentrations and without metabolic activation. A fractionation technique was developed and subfractions (dichlormethane and dichlormethane/methanol) were tested for their mutagenic potential and PAH-content. Small amounts of polycyclic aromatic hydrocarbons (PAH) were found, which were concentrated to an extent of 90% on the dichlormethane fraction. The results showed a tendency of reactivity to concentrate in the polar fraction.

Chemical Fractionation↗
PubMed1990

[Use of UV radiation for the disinfection of water. IV. Microbiological studies of the UV sensitivity of different aged cells of E. faecium, E. coli and P. aeruginosa].

With a flow-through u.v. light treatment apparatus the u.v.-susceptibility of E. faecium, E. coli and P. aeruginosa in drinking water was tested. The investigations were done with cells harvested in the exponential phase of growth. One part of the suspensions was used immediately (= 0 days old cells), two other parts were stored for 5 and 7 days in sterilised drinking water in the dark at room temperature (= 5 and 7 days old cells). In either case--0 or 5 and 7 days old cells--reductions of at least 99.999% were obtained by a dosage of 25 mWs/cm2. No difference concerning the u.v.-susceptibility could be noticed between the different kind of cells of E. faecium, E. coli, and P. aeruginosa.

Bacteria↗
PubMed1990

[Performing surface and room disinfection in the hospital].

At a Berlin university hospital the regulations governing area disinfection were rendered mandatory for disinfectors by a service ordinance. The primary consideration, besides general hygienic aims, concerned the possibility of transmitting infections in the hospital. Classification into four degrees of infection or contamination led to an almost uniform type of disinfection measures, dominated by "wipe" disinfection using concentrations recommended by the German Association for Hygiene and Microbiology (Deutsche Gesellschaft für Hygiene und Mikrobiologie = DGHM) (the four degrees of infection being: I: no nosocomial infectious diseases, II: nosocomial infectious diseases, III: diseases that can be transmitted and are subject to mandatory reporting, IV: highly contagious diseases that can be transmitted on airborne basis and are subject to mandatory reporting). Room disinfection via evaporation or smoke screen with formaldehyde is now performed only in conjunction with degree No. IV listed above. Area disinfection methods under dispute, such as routine room disinfection or as a prophylactic measure, were discontinued for medico-toxicological and environmental hygiene reasons. The considerations and discussions resulting from the concept of area disinfection resulted in abolishing inadequately indicated disinfection measures at the university hospital.

Air Microbiology↗
PubMed1990

[Medical wastes. 2. Comparative studies of the microbial contamination of wastes from medical practices of different disciplines and household garbage].

Medical consulting room wastes of 7 disciplines were investigated quantitatively and qualitatively for nosocomial infective agents. 20-25 samples from each consulting room were examined for 3 months. The results were compared with those of household refuse and hospital wastes. The whole content of a waste bag was suspended without a preceding sorting and the eluate was microbiologically examined. The results of the investigations proved, that the germ concentration of the medical consulting room wastes was less than that of household refuse. The median for all investigated germ groups was less than 1 log(10)-step compared-to household refuse. The statistical analyses confirmed highly significant differences (p less than 0.001) for total germ concentration, thermoresistant obligate aerobic and facultative anaerobic bacteria and bacteria spores. Exceptionally the paediatric consulting room wastes show smaller differences (p less than 0.01) between the household refuse for obligate and facultative anaerobic bacteria, thermoresistant obligate and facultative anaerobic bacteria and bacteria spores and D-streptococci. From the comparison of total germ concentration for medical wastes from conservative disciplines and household refuse resulted that wastes from medical consulting rooms are less contaminated with nosocomial infective agents than household refuse and hospital wastes. In conclusion wastes from medical consulting rooms can, similar to hospital wastes, be disposed together with household refuse.

Bacteria↗
PubMed1989

[Evaluation of technical indoor air ventilation systems in operating departments from the health viewpoint].

By means of measurement examples it is shown that the examination of the cfu-concentration in the supply-air is not a sufficient criterion for the hygienic-microbiological evaluation of air-conditioning systems in operation wards. Maximum upper values for cfu-concentration were only exceeded a little in some cases. Particle measurements, carried out simultaneously, gave further information on the hygienic status of the air supplied by the air-conditioning system and permitted an evaluation of the ventilation system (for example an air-supply ceiling with a stabilized air ventilation). An efficient air-ventilation system should have the effect that the air quality in the operation area is of nearly the same quality as the supply-air. On the basis of own measurements maximum upper values and recommended values for cfu- and in particular particle-concentrations in the supply-air of air-conditioning systems with three-step filtration were proposed. The set-up and the carrying out of the measurement is described to standardize a "hygienic evaluation" of air-conditioning systems in operation theatres. Help for the interpretation of measurement results is given by means of measurement examples.

Air Microbiology↗
PubMed1989

[Public health-microbiological evaluation of housekeeping combinations for cleaning and disinfecting bed pans in the hospital].

For prophylaxis of infection in hospital and for staff care protection the bed pans used by hospital patients should be disinfected. Nowadays this is done mostly thermically in automatic disinfection systems. In Germany there is no regulation for the hygienic-microbiological check-up of these machines. The routine testing method for disinfection machines of bed pans is demonstrated. Under hygienic-microbiological aspects the technical procedures in disinfection machines are described and explained.

Bacteriological Techniques↗
PubMed1989

[Use of UV rays for the disinfection of water. III. UV sensitivity of Legionella pneumophila of different ages in cold and warm drinking water].

In drinking water the sensitivity of L. pneumophila serogroup 1 type Philadelphia and L. pneumophila serogroup 5 type Dallas were studied with a flowthrough u.v. light treatment apparatus. By washing purified cells from broth cultures were used as inoculum directly ( = young cultures) or kept 2-3 weeks in drinking water in the dark ( = old cultures). A decrease of 99,9999% was found after u.v. treatment by 19 mWs/cm2 for young cultures and by 15 mWs/cm2 for old cultures. Reductions of 99,9999% were obtained by 16 mWs/cm2 in cold drinking water (13-16 degrees C) and by 13 mWs/cm2 in warm drinking water (45-47 degrees C). L. pneumophila serogroup 1 and L. pneumophila serogroup 5 show a very similar susceptibility to u.v.-irradiation. Reductions of 99,9999% were obtained by 14 mWs/cm2 and 15 mWs/cm2, respectively. Thus L. pneumophila-suspensions proved to be more sensitive to u.v.-irradiation than E. coli oder E. faecium in earlier experiments.

Age Factors↗
PubMed1989

[Medical waste. 1. Microbiologic studies of wastes of various specialties at a large and small hospital in comparison to housekeeping waste].

Hospital wastes, similar to household refuse, from normal and high risk areas of a big and a smaller hospital were tested quantitatively and qualitatively for nosocomial infective agents. The results were compared with those of household refuse. 20-25 samples from care and operating wards were examined each for 3 months. The whole content of a waste bag was suspended without a preceding sorting. After this treatment the eluat was microbiologically examined. The results of the test proved that the germ concentration of the hospital waste was less or similar than that of household refuse. The median for gram negative rods in household refuse was e.g. 4 log10-steps higher than in wastes from operating wards. The statistical analysis confirmed these highly significant differences between the wastes from the high risk operating areas of the big and smaller hospital and the household refuse for all investigated bacteria groups. There are nearly no differences between the wastes from normal wards and from household refuse regarding germ concentration for different groups, e.g. gram negative rods or D-streptococci, and no higher germ concentration in any case. In conclusion hospital wastes must be disposed with special hygienic measures inside the hospital, outside the hospital they can be disposed together with household refuse.

Bacteria↗
PubMed1989

[Chemical and biological characterization of electrofilter dusts of a waste incinerator. 1. Comparison of different extraction methods for organic dust contents and their mutagenicity].

Particles collected by electrostatic precipitation from a municipal waste incinerator were used to study sample extraction methods for the mutagenicity bioassay. The Ames-Salmonella typhimurium plate incorporation method with tester strain TA 100 was employed. A series of organic solvents with different polarities was employed to identify the most efficient solvent for removing mutagens from the ashes: Soxhlet extraction with toluene and pretreatment with diluted HCl; Soxhlet extraction with toluene following 2-ethoxy-ethanol; reflux extraction with toluene: 2-ethoxy-ethanol: HCl conc.; Soxhlet extraction with dichloromethane. The results demonstrate that the amount of extractable mass correlates with the polarity of the solvents; however, the extractable mass did not correlate with the mutagenic activity of the extracts. The Soxhlet extraction with toluene and pretreatment with diluted HCl proved to be the best method for the extraction of mutagenic compounds present in particles collected by electrostatic precipitation from municipal waste incinerators, although it does not remove the maximum amount of extractable organic matter from the particles.

Dust↗
PubMed1989

[Nitrated polycyclic aromatic hydrocarbons (nitro-PAH) in the suspended substances of the atmosphere. 2. Comparison of the mutagenicity of nitro-PAH and dust extracts of the air in the Ames, SOS repair induction and SCE test].

Extracts of airborne suspended particulate matter were assayed in the Ames-test with strain TA 98, in the SOS chromotest (test on induction of the SOS repair) with strains E. coli PQ37 and S. typhimurium TA 1535 and in the sister chromatid exchange test. Samples from Berlin-Wedding were extracted by dichloromethane and tested up to the limits of solubility. All three test systems showed biologic activity. In the Ames- and the SOS chromotest these extracts revealed higher activity with S9-mix. 4 nitro-PAH, which are known to be present in ambient urban air, were assayed in these test systems, checking them additionally with strains TA 1538, TA 100 and TA 1535 in the Ames-test. In this test these compounds appeared to be direct acting frameshift mutagens and their activity is diminished by addition of S9-mix. On the contrary these compounds were either active at all or more active in the SOS chromotest in the presence of S9-mix. In the SCE-test only with exogenous activation a raise of the SCE frequency could be detected.

Air Pollutants↗
PubMed1988

[Polar neutral organic compounds (POCN) in city aerosols. 3. Comparative studies of emission and immission particles in West Berlin].

After the concentration of the polar organic compounds (= POCN), especially from the neutral fraction, was investigated in urban suspended particulates over a longtime period in Berlin (West) (March 1983-January 1984 at three emission measurement stations loaded by different sources) and some emissions were taken during 1985 from vehicle diesel-engines and private coal firing (domestic fuel) a comparison between all these measurements are given now. The following results were gained: The amount of the ether-extractable organic matter (= EEOM) was higher for the emission samples (less than or equal to 80% of the total suspended particulate matter = TPM) than for the emission measurements (less than or equal to 40% of the TPM). Most of the EEOM was found for particle sizes less than or equal to 1.5-2 micron aerodynamic diameter. Making further separation of the EEOM, then the neutral fraction (= NF) showed the highest percentage of about 60-90% (of the EEOM) for emission measurements and of 60-80% for emission measurements. The values of the acidic fraction (= AF) were with 5-30% (emissions) and 10-25% (emissions). Quite the same results were found for the basic fraction (= BF) with 1-20% (emissions) and 5-20% (emissions). Of the neutral fraction, further separation was done into aliphatic compounds (= AIP), polycyclic aromatic hydrocarbons (= PAH) and polar neutral organic compounds (= POCN). From these compounds, the aliphatics amounted to 30-40% (of the NF) for the vehicle emission measurements and to only 10-20% for the coal firing emissions. The percentages of the PAH and POCN varied and were quite similar with 10-50% (PAH) and 25-50% (POCN). For the emission measurements, the PAH amounted to lower values (5-30%) and the POCN to (30-60%). Some differences between the measurements were found in the gas chromatographic analysis of single PAH and POCN compounds. Then, for the vehicle samples (diesel engines and highway traffic tunnel) higher concentrations were found for perylene and coronene (of the PAH) and for mainly 1-nitropyrene (of the POCN) in comparison with coal firing emissions. There, we found higher concentrations for phenanthrene, benzo(a)pyrene and dibenz(a,h) anthracene (of the PAH) and for 9-fluorenone (of the POCN). The concentration of the nitro-groups containing substances (included in the POCN-fraction) amounted here generally to higher values in comparison with the vehicle emissions (except of 1-nitropyrene).(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants↗
PubMed1988

[The use of UV rays for the disinfection of water. I. Microbiologic studies of drinking water].

As a physical disinfection method without chemicals required the ultraviolet irradiation was tested for disinfection of drinking water. The survival was measured as a function of exposure to radiation for S. enteritidis, E. cloacae, C. freundii, S. marcescens, E. coli, K. pneumoniae und S. faecium. The bacteria were grown in trypton soya broth until they were well into the exponential phase. Two different UV-disinfection units were tested. Both consist of cylindrical shaped chambers with one low-pressure mercury-discharge lamp with their longitudinal axis parallel to the chambers. With 10(6) cfu/ml the experiments were done with three different rates of flow of 7,2 m3/h, 4,0 m3/h and 2,0 m3/h. The minimum exposures to radiation necessary to cause a 99.999% reduction were 10-86 mWs/cm2 depending on the test bacterium and on the UV-disinfection unit. The minimum doses ranged for S. enteritidis up to 13 mWs/cm2, for E. coli up to 21 mWs/cm2, for K. pneumoniae up to 39 mWs/cm2, for S. faecium up to 42 mWs/cm2, for E. cloacae up to 43 mWs/cm2, for C. freundii up to 72 mWs/cm2, and for S. marcescens up to 86 mWs/cm2.

Bacteria↗
PubMed1988

[The behavior of polychlorinated biphenyls (PCB) in water purification plants. I. Mathematical balancing in a model purification plant].

The behaviour of 39 PCB-isomers will be tested in a model sewage plant. Their distribution is described mathematically and the quantities of the partial streams are calculated. Because there is no loss of PCB through the ventilation of the activated sludge tank and according to the isomeric mass balance, it can be concluded that the less chlorinated PCB are decomposed microbially while all of the higher chlorinated PCB are found in the sludge and the effluent of the model plant.

Biodegradation, Environmental↗
PubMed1988

[The behavior of polychlorinated biphenyls (PCB) in a water purification plant. II. A mathematical balancing of the Ruhleben purification plant in Berlin].

Studies on PCB concentration and their distribution in waste water sludge of a municipal sewage plant are made. The incoming sewage has an average concentration of 813 ng/l, the effluent still contains 108 ng/l. The biggest part of the PCB is accumulated in the sludge. A comparison of the in- and output of PCB and the average PCB-patterns at the various sampling sites of the sewage plant shows that the PCB are not transformed or decomposed microbially.

Berlin↗