Established malanoma cell lines were fixed in suspension with 4% formalin and tested for antigenic activity against sera from melanoma patients in a micro-immune adherence test. By incubation of ...formalin-fixed cells in serum-free medium the unspecific background rosette formation was substantially reduced to below 10%. As could be demonstrated in absorption experiments with viable and formalin-fixed tumor cells, surface antigens reacting with sera from melanoma patients are largely unaffected by formalin treatment.
Due to its high toxicity, no safe alimentary uptake level can be defined for lead. Therefore, an effort has to be made to minimize lead intake. Game meat belongs to the foods with a comparatively ...high lead content. A research project was carried out to study the effect of lead-based ammunition as compared to non-lead ammunition on contamination of game (roe deer, Capreolus capreolus and wild boar, Sus scrofa) with lead. Results of the research project clearly show that lead-based hunting ammunition significantly increases the lead concentration in the game meat. The effect of the construction of lead ammunition was also studied. Unexpectedly, there was a tendency in roe deer for bonded bullets to show higher lead contamination than fragmenting bullets. No such effect was noted in wild boar. In roe deer the point of impact of the projectile appears to have an influence on the levels of lead contamination. Increased lead levels were observed when a bone hit was reported. For wild boar no significant difference in lead contamination between a bone hit or a non-bone hit was observed. Non-lead bullets in combination with suitable game meat hygienic measures can therefore be recommended to minimize the uptake of lead in order to protect the consumers.
P. J. Bickel's approach to and results on estimating the parameter vector β of a conditionally contaminated linear regression model by asymptotically linear (AL) estimators$\hat\beta^\ast$which have ...minimum trace of the asymptotic covariance matrix among all AL estimators with a given bound b on their asymptotic bias (MT-AL estimators with bias bound b) is here extended to conditionally contaminated general linear models and in particular for estimating arbitrary linear aspects φ(β) = Cβ of β which are of actual interest in applications. Admitting that β itself is not identifiable in the model (also a practically important situation), a complete characterization of MT-AL estimators with bias bound b including the case where b is smallest possible is presented here, which extends and sharpens H. Rieder's characterization of all AL estimators with minimum asymptotic bias. These characterizations (Theorem 1) represent generalizations (in different directions) of those which define Hampel-Krasker estimators for β in linear regression models and admit (Theorem 2) explicit constructions of MT-AL estimators under generally applicable model assumption. Obviously, even in linear regression models,$\hat\varphi^\ast = C\hat\beta^\ast$is not an MT-AL estimator for φ if$\hat\beta^\ast$is one for β (there does not even exist an AL estimator nor an M estimator for β, if β is not identifiable in the model). Examples such as quadratic regression illustrate the not at all obvious relation between$\hat\beta^\ast$and$\hat\varphi^\ast$, demonstrate the applicability of the general results and show explicitly the influence of the parametrization and the underlying design of the linear model.
Trichloroethylene (TCE) is a solvent that widely contaminates groundwater. Neutral pH has been shown to optimize TCE reductive dehalogenase activity in cell extracts and cell suspensions. Anaerobic ...bacteria from TCE-contaminated subsurface sediment might also show maximum dechlorinating activity when the pH is neutralized in the sediment. Encapsulated phosphate buffers were investigated as a method for controlling pH in situ where neutral pH might improve dechlorination of TCE. These capsules (1 mm average diameter), which are coated with a pH-sensitive polymer (Eudragit™ S100), release KH2PO4 into sediment pore water when pH levels rise above 7.0. These capsules were tested in sediment microcosms and sand and sediment flow-through columns. The sediment was obtained from a contaminated groundwater aquifer at the Department of Energy's Savannah River Site (SRS). The initial test of capsule release occurred in denitrifying sediment microcosms. pH levels above 8.0 were measured in microcosms to which no capsules had been added while the pH in bottles containing capsules remained within 0.2 pH units of 7.0. Two more tests to characterize the capsules were performed in sand columns specially designed to house the capsules. Near complete conversion of 80 mg N/L of nitrate and 152 mg/L of ethanol per day resulted in a mean pH increase from 6.2 to 8.2 in the column without capsules. The column containing the capsules maintained the target pH of 7.0 ± 0.2 for four weeks. The encapsulated phosphate buffer was effective at neutralizing a 1.5-unit pH change in saturated sediment microcosms and sand columns. This study demonstrates the potential for this technology to mediate pH changes in situ. The pH in microcosms containing sediment from SRS was adjusted to different set points in order to determine whether 7.0 is the optimum pH level for reductive dechlorination of TCE in sediment. Statistically, maximum vinyl chloride production occurred at a pH of 4 (p < 0.0001). The results implied that a pH of 7 would not necessarily optimize TCE dechlorination in sediment. Though pH appeared to have affect TCE dechlorination, the low production of metabolites indicated that in situ pH control would not be efficacious for promoting reductive dechlorination at SRS.
We use the local maxima of a redescending M-estimator to identify clusters, a method proposed already by Morgenthaler (1990) for finding regression clusters. We work out the method not only for ...classical regression but also for orthogonal regression and multivariate locations and give consistency results for all three cases. The approach of orthogonal regression is applied to the identification of edges in noisy images.
EFSA's Scientific Panel on Biological Hazards (BIOHAZ) was asked for a scientific opinion on an alternative method for processing Category (Cat) 2 Animal By‐Products (ABP). The materials to be ...treated are placentas and fallen pigs; this implies that the animals died due to a disease, which in most cases was not properly diagnosed. The target parameters are: i) particle size less than 150 mm and ii) heating for 10–12 hours at 100°C. The end‐product obtained is mixed with pig slurry and used as an organic fertiliser. According to the legislation in force, before being used as an organic fertiliser, Cat. 2 material should be treated with a sterilisation process (i.e. 133°C / 20 min / 3 bars / 50 mm particle size). The most resistant hazards identified by the applicant as target to demonstrate the risk reduction are spores of pathogenic clostridia. Due to uncertainty on the cause of the animals’ death, the presence of more resistant hazards cannot be considered negligible. The sterilisation process defined in the current legislation is able to minimise the risks due to unidentified agents, such as Bacillus anthracis and TSE agents. The BIOHAZ Panel concluded that the process proposed was not properly validated experimentally under real scale conditions. In theory, it should permit a high degree of reduction of spores of pathogenic clostridia but because of several uncertainties (i.e. water evaporation, fat protective effect and particle size) it is not certain that the values of the parameters used in the theoretical calculations would apply in practice. Moreover, the proposed alternative method cannot be considered equivalent to the sterilisation process defined in the current legislation. This would be particularly relevant in the case of extremely heat resistant spores being present in the material to be treated.
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