Temporal trend studies on tetra- and pentabrominated diphenyl ethers and hexabromocyclododecane in guillemot egg from the Baltic Sea

Guillemot eggs from the Baltic Sea, sampled between 1969 and 2001, were analyzed for tetra- and pentabromodiphenyl ethers (2,2',4,4'-tetraBDE (BDE-47), 2,2',4,4',5-pentaBDE (BDE-99), and 2,2',4,4',6-pentaBDE (BDE-100)), and hexabromocyclododecane (HBCD). This temporal trend study indicates that the concentrations of the polybrominated diphenyl ether compounds increased from the 1970s to the 1980s, peaking around the mid- to the late-1980s. These peaks are then followed by a rapid decrease in concentrations during the rest of the study period, with the concentrations of the major BDE congener below 100 ng/g lipid weight at the end of the period. This corresponds to less than 10% of its peak values. The concentrations of HBCD show a different pattern over time. After a peak in the middle of the 1970s followed by a decrease, the concentrations increased during the latter part of the 1980s. During the recent 10-yr period no significant change has occurred, and the annual mean concentrations are more or less stable at a higher level as compared to the beginning of the study period.     

Potential of Bacillus cereus for producing an emetic toxin,cereulide, in bakery products: quantitative analysis by chemical and biological methods

A method for the direct quantitative analysis of cereulide, the emetic toxin of Bacillus cereus, in bakery products was developed. The analysis was based on robotized extraction followed by quantitation of cereulide by liquid chromatography-mass spectrometry and an assay of toxicity by the boar sperm motility inhibition test. The bioassay and the chemical assay gave comparable results, demonstrating that the extracted cereulide was in a biologically active form. Cereulide was formed when cereulide-producing B. cereus strains were present at > or = 10(6) CFU/g in products with water activity values of > 0.953 and pHs of > 5.6. Rice-containing pastries accumulated high contents of cereulide (0.3 to 5.5 microg/g [wet weight]) when stored at nonrefrigeration temperatures (21 to 23 degrees C). Cereulide was not formed in products stored at refrigeration temperatures (4 to 8 degrees C). Cereulide is not inactivated by heating during food processing. Therefore, direct analysis of this toxin in food is preferable to cultivating methods for assessing the risk of food poisoning by emetic B. cereus.     

Developmental Exposure to Endocrine Disrupter DDT Interferes with Age-Related Involution of Thymus

The impact of endocrine-disrupting chemicals on the development and involution of the immune system is a possible reason for the increased incidence of disorders associated with inappropriate immune function. The thymus is a lymphoid and also an endocrine organ, and, accordingly, its development and functioning may be impaired by endocrine disruptors. The aim was to evaluate age-related thymus involution in mature rats exposed to the endocrine disruptor DDT during prenatal and postnatal ontogeny. Methodology included in vivo experiment on male Wistar rats exposed to low doses of DDT during prenatal and postnatal development and morphological assessment of thymic involution, including the immunohistochemical detection of proliferating thymocytes. The study was carried out at the early stage of involution. Results: DDT-exposed rats exhibited a normal anatomy, and the relative weight of the thymus was within the control ranges. Histological and immunohistochemical examinations revealed increased cellularity of the cortex and the medulla, higher content of lymphoblasts, and more intensive proliferation rate of thymocytes compared to the control. Evaluation of thymic epithelial cells revealed a higher rate of thymic corpuscles formation. Conclusion: The data obtained indicate that endocrine disrupter DDT disturbs postnatal development of the thymus. Low-dose exposure to DDT during ontogeny does not suppress growth rate but violates the developmental program of the thymus by slowing down the onset of age-related involution and maintaining high cell proliferation rate. It may result in excessive formation of thymus-dependent areas in peripheral lymphoid organs and altered immune response.     

Self-diffusion of oil in lubricating greases by NMR

Self-diffusion of base oil in six model lubricating greases and in the base oils themselves was measured using pulsed-field gradient nucleic magnetic resonance (NMR) at 23, 40, 70, and 90°C. Three of the greases were based on naphthenic mineral oils, and three were based on synthetic polyalphaolefin oils. Soaps of 12-hydroxy stearic acid were used as thickener agents in all six greases. The purpose of the investigation using NMR was to see if structure varies with temperature, and if NMR is a viable method for structure determination. The ratio between the diffusion coefficient of the base oil in the grease and the neat base oil in itself was evaluated as a function of temperature. This ratio was taken as a direct indicator of the obstruction effect that the thickener has on the oil. The thickener showed a stronger obstruction effect on the base oil in the synthetic grease than in the mineral-based grease. This was related to the soap content, which, for these greases, is roughly twice as high in the synthetic greases as in the mineral ones. The obstruction effect was constant in the temperature range 40–90°C for mineral- as well as synthetic-based greases. NMR was judged to be a promising method for investigating how the gellant affects the diffusion coefficient of oil in a lubricating grease.