Homologous recombination (HR) deficient cells are sensitive to methyl methanesulfonate (MMS). HR is usually involved in the repair of DNA double-strand breaks (DSBs) in Saccharomyces cerevisiae ...implying that MMS somehow induces DSBs in vivo. Indeed there is evidence, based on pulsed-field gel electrophoresis (PFGE), that MMS causes DNA fragmentation. However, the mechanism through which MMS induces DSBs has not been demonstrated. Here, we show that DNA fragmentation following MMS treatment, and detected by PFGE is not the consequence of production of cellular DSBs. Instead, DSBs seen following MMS treatment are produced during sample preparation where heat-labile methylated DNA is converted into DSBs. Furthermore, we show that the repair of MMS-induced heat-labile damage requires the base excision repair protein XRCC1, and is independent of HR in both S.cerevisiae and mammalian cells. We speculate that the reason for recombination-deficient cells being sensitive to MMS is due to the role of HR in repair of MMS-induced stalled replication forks, rather than for repair of cellular DSBs or heat-labile damage.
This study assesses the total suspended solids (TSS) retention capacity of different organic filter media for two potential applications: (i) a polishing unit for package treatment plants and (ii) a ...pretreatment for blackwater from low-flushing toilets. The results showed that the peat filter media used can be significantly improved in terms of structural stability and TSS removal capacity by mixing it with sawdust. Most of the TSS accumulated in the upper part of the filter material, and filter thickness exceeding 15 cm had no statistically significant effect (P < 0.1) on the TSS treatment performance. The experimental system reached a TSS reduction of 60-70% for blackwater and 80-90% for simulated effluent peaks from a package treatment plant. The main challenge of a full-scale application of an organic filter is the issue of clogging, especially when treating concentrated blackwater. However, this work indicates that a clogged filter media can be regenerated by mixing the uppermost filter layer without significant loss of filter performance regarding TSS. More research is needed to develop an appropriate mechanical unit for automatic filter media regeneration.
Abstract Background and aims A considerable number of Europeans suffer from chronic pain and are using opioids, particularly of the weak type. It is a clinical impression that many of these are ...driving or wish to drive a car. The aims of this study were to investigate if codeine influences driving ability in a simulator, and to examine if chronic pain per se might impair such functions. Methods Twenty patients with chronic pain on long-term codeine therapy were compared to 20 chronic pain patients not using codeine in a video driving simulator test. The chronic pain patients were then compared to 20 healthy controls. The primary outcome measures were reaction time and number of missed reactions. Results The patients using codeine 120–270 mg (mean 180 mg) daily showed the same driving skills as patients not using codeine, and the codeine level did not affect the results. This was the case both 1 h after intake of a single dose of 60 mg codeine and five or more hours after the last codeine intake. The reaction times were significantly slower for the chronic pain patients, in both rural and urban driving conditions, compared to the healthy controls (difference 0.11 s. and 0.12 s., respectively). The chronic pain patients missed almost twice as many reactions to traffic signs. There were no difference between the groups in steering precision. Conclusion The main finding in this simulator study was that codeine does not impair driving-related abilities over and above what is associated with chronic pain per se.
At Vidaråsen in Norway sewage from a community consisting of 160 people, including a dairy, a food processing workshop, a bakery and a laundry is treated using a pond/reed bed system. The system ...consists of sludge settlement, pre-treatment surface/vertical-flow constructed wetlands, a 5 m deep enhanced facultative pond, three stabilization ponds, a planted sand filter and finally two horizontal-flow constructed wetlands filled with lightweight aggregate (Filtralite-P). The enhanced facultative pond and the primary stabilization pond are equipped with Flowform-cascades, which provide year-round aeration, rhythmical treatment and mixing of wastewater in the ponds. Treatment performance during the first five years has been high and unaffected by harsh winter conditions. Average phosphorus discharge from the system is 0.25 mg/l with total nitrogen 4 mg/l, total organic carbon (TOC) 5 mg/l and thermo-tolerant coliforms < 100/100 ml. The system is ecologically diverse and supports abundant populations of higher aquatic life such as ducks, amphibians and carp.
Values for reaction-kinetic parameters of electrophiles can be used to predict mutagenic potency. One approach employs the Swain–Scott relationship for comparative kinetic studies of electrophilic ...agents reacting with nucleophiles. In this way glycidamide (GA), the putatively mutagenic/carcinogenic metabolite of acrylamide, was assessed by determining the rates of reaction with different nucleophiles. The rate constants (
k
Nu) were determined using the “supernucleophile” cob(I)alamin Cbl(I) as an analytical tool. The Swain–Scott parameters for GA were compared with those of ethylene oxide (EO). The substrate constants,
s values, for GA and for EO were found to be 1.0 and 0.93, respectively. The reaction rates at low values of nucleophilic strength (
n
=
1–3), corresponding to oxygens in DNA, were determined to be 2–3.5 times higher for GA compared to EO. GA was also more reactive than EO towards other nucleophiles (
n
=
0-6.4). The mutagenic potency of GA was determined in Chinese hamster ovary cells (
hprt mutations in CHO-AA8 cells per dose unit with gamma-radiation as reference standard). The potency of GA was estimated to be about three mutations per 10
5 cells and mMh corresponding to about 400
rad-equ./mMh. A preliminary comparison of the mutagenic potency (per mMh and as rad-equivalents) of GA and EO shows an approximately seven times higher potency for GA. A higher mutagenic potency of GA compared to EO is compatible with expectation from reaction-kinetic data of the two compounds. The data confirmed that GA is not a strong mutagen, which is in line with what is expected for simple oxiranes. The present study shows the value of cob(I)alamin for the determination of reaction-kinetic parameters and their use for prediction of mutagenic potency.
Ecological sanitation has been shown to be economically feasible and environmentally sustainable. However, cultural factors affecting the choice of sanitation solutions have not yet been sufficiently ...investigated, particularly not in Muslim communities. To understand the perceptions of rural Muslim communities regarding alternative sanitation systems, members of households, key informants and women and men's focus groups in Machaki village in the district of Karak, North West Frontier Province (NWFP), were interviewed. A menu of both ecological and conventional sanitation options was put forward for consideration. All respondents were strongly opposed to the urine-separating latrines and in favor of flush toilets. They see any form of latrines as an age-old fashion, backwards and a matter of taboo, while flush toilets are considered prestigious and desirable. Muslim practices of anal cleansing together with the strict religious prohibition of contact with urine and faeces are factors influencing the reluctance towards latrines. The physical appearance of faeces and urine in latrines is repulsive to people. However, the material is less objectionable once it has disappeared in water and relocated to a treatment site. The rural community showed interest in the construction of improved sanitation consisting of flush toilets and an underground sewerage system and recycling of plant nutrients from urine and faeces through treatment in constructed wetlands. The study underlines the importance of incorporating cultural preferences in the planning of improved sanitation, particularly when designing low-cost ecological systems.
The purification capacity of systems using floating aquatic plants depend on the climatic conditions under which they are used. This study from Cuban conditions evaluate the effects of the organic ...loading rate, hydraulic loading rate and water depth on the purification capacity of water hyacinths, as well as the effect of some climatic variables on the kinetics of the treatment processes. The experimental system consisted of two consecutive tanks simulating a system of ponds in series. The water depths used were 0.5 m and 1.12 m. In the shallower system with shorter retention times and greater superficial organic loading higher removal efficiencies are obtained. With the data obtained, empirical relations were sought. From these correlations it is possible to determine the values for some parameters used in the design of aquatic treatment systems with water hyacinths. The results revealed a relationship between the purification capacity of the water hyacinth and its velocity of growth. The specific velocity of growth varied with the months of the year and was associated with the temperature and the solar radiation. A multiple correlation equation describing these relations was obtained.
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