Degradation of nonylphenol in spiked soils and in soils treated with organic waste products

Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the accumulation and effects of nonylphenol (NP) in the soil ecosystem. We have thus studied the degradation of NP and possible uptake in agricultural plants in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated into a sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napus L. cv Hyola 401) was sown in the pots and harvested after 30 d. In order to investigate the influence of plant growth on the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight. No plant uptake was observed above the detection limit at 100 ppb dry weight. When NP was added as waste to the soil, plant growth significantly stimulated the degradation. In experiments with anaerobic and aerobic sludge, respectively, 13 and 8.3% of NP remained in the soil from pots planted with rape compared with 26 and 18% in soil without plant growth. When NP was added as a spike to soil, the degradation was more complete and plant growth did not influence the degradation. Percentages of 2.2 and 1.8 were still in the soil at harvest for planted and plant-free pots, respectively. The degradation of NP was more extensive in sludge-amended soil compared with compost.     

The organization of repeating units in mitochondrial DNA from yeast petite mutants

Summary We have reinvestigated the linkage orientation of repeating units in mtDNAs of yeast ^– petite mutants containing an inverted duplication. All five petite mtDNAs studied contain a continuous segment of wild-type mtDNA, part of which is duplicated and present in inverted form in the repeat. We show by restriction enzyme analysis that the non-duplicated segments between the inverted duplications are present in random orientation in all five petite mtDNAs. There is no segregation of sub-types with unique orientation. We attribute this to the high rate of intramolecular recombination between the inverted duplications. The results provide additional evidence for the high rate of recombination of yeast mtDNA even in haploid ^– petite cells.We conclude that only two types of stable sequence organization exist in petite mtDNA: petites without an inverted duplication have repeats linked in straight head-to-tail arrangement (abcabc); petites with an inverted duplication have repeats in which the non-duplicated segments are present in random orientation.     

Formaldehyde-releasers: relationship to formaldehyde contact allergy. Contact allergy to formaldehyde and inventory of formaldehyde-releasers

This is one of series of review articles on formaldehyde and formaldehyde-releasers (others: formaldehyde in cosmetics, in clothes and in metalworking fluids and miscellaneous). Thirty-five chemicals were identified as being formaldehyde-releasers. Although a further seven are listed in the literature as formaldehyde-releasers, data are inadequate to consider them as such beyond doubt. Several (nomenclature) mistakes and outdated information are discussed. Formaldehyde and formaldehyde allergy are reviewed: applications, exposure scenarios, legislation, patch testing problems, frequency of sensitization, relevance of positive patch test reactions, clinical pattern of allergic contact dermatitis from formaldehyde, prognosis, threshold for elicitation of allergic contact dermatitis, analytical tests to determine formaldehyde in products and frequency of exposure to formaldehyde and releasers. The frequency of contact allergy to formaldehyde is consistently higher in the USA (8–9%) than in Europe (2–3%). Patch testing with formaldehyde is problematic; the currently used 1% solution may result in both false-positive and false-negative (up to 40%) reactions. Determining the relevance of patch test reactions is often challenging. What concentration of formaldehyde is safe for sensitive patients remains unknown. Levels of 200–300 p.p.m. free formaldehyde in cosmetic products have been shown to induce dermatitis from short-term use on normal skin.     

Probabilistic acute dietary exposure assessments to captan and tolylfluanid using several European food consumption and pesticide concentration databases

Probabilistic dietary acute exposure assessments of captan and tolylfluanid were performed for the populations of the Czech Republic, Denmark, Italy, the Netherlands and Sweden. The basis for these assessments was national databases for food consumption and pesticide concentration data harmonised at the level of raw agricultural commodity. Data were obtained from national food consumption surveys and national monitoring programmes and organised in an electronic platform of databases connected to probabilistic software. The exposure assessments were conducted by linking national food consumption data either (1) to national pesticide concentration data or (2) to a pooled database containing all national pesticide concentration data. We show that with this tool national exposure assessments can be performed in a harmonised way and that pesticide concentrations of other countries can be linked to national food consumption surveys. In this way it is possible to exchange or merge concentration data between countries in situations of data scarcity. This electronic platform in connection with probabilistic software can be seen as a prototype of a data warehouse, including a harmonised approach for dietary exposure modelling.     

Enhanced repair of O6-methylguanine in liver DNA of rats pretreated with phenobarbital, 2,3,7,8-tetrachlorodibenzo-p-dioxin, ethionine, or N-alkyl-N-nitrosoureas

Rats were pretreated for a number of weeks with the liver tumourpromoters phenobarbital and 2, 3, 7, 8-tetrachlorodi-benzo-p-dioxin,the direct alkylating agents N-ethyl-N-nitrosourea and N-methyl-N-nitrosourea,and the hepatocardnogens ethionine and diethylnitrosamine. Asubsequent challenge with a single, low dose of radioactivelylabelled dimethyl-nitrosamine was given to assay the capacityof the liver for O⁶-methylguanine repair. Pretreatment with0.05% phenobarbital in the diet for 8 weeks (a promoting regimen)resulted in significantly enhanced O⁶-methylguanine repair;shorter pretreatment periods (3 days or 2 weeks) had no significanteffect. Repeated injection of another liver tumour promoter,2,3, 7, 8-tetrachlorodibenzo-/>-dioxin, also resulted inenhancement of O⁶methylguanine repair. Pretreatment for 2 weekswith N-ethyl-N‘-nitrosourea resulted in strongly enhancedO6-methylguanine repair, as did a similar pretreatment withdiethylnitrosamine, which was included as a positive control.The same pretreatment scheme which was highly effective in thecase of N’-ethyl-N-nitrosoiirea, was found to be totallyin effective in the case of N-methyl-N-nitrosourea. When N methyl-N-nitrosoureawas administered for 8 weeks instead of 2, a small but statisticallysignificant increase in O⁶-methyl-guanine repair was observed.It is concluded that two factors are responsible for the loweffectivity of N-methyl-N-nitroso-urea. The first is the relativelylow extent of liver DNA methylation by this compound when comparedwith dimethyl-nitrosamine. The second is the low efficiencyof methylating agents (expressed per extent of DNA alkylation)to induce O⁶-methylguanine repair in rat liver when comparedwith ethylating agents. Pretreatment for 2 weeks with a dietcontaining DL-ethionine also resulted in a substantially increasedO⁶-methylguanine repair capacity. Neither this enhancement,nor that induced by a pretreatment with diethylnitrosamine,could be inhibited by simultaneous feeding of a methionine-enricheddiet. Our results indicate that neither increased hepatocellularproliferation nor direct interaction with DNA are necessaryfor the induction of O⁶-methylguanine repair enhancement. Itis concluded that the capacity of an agent to enhance O⁶-methylguaninerepair in rat liver reflects the hepato(co)carcinogenic capacityof that agent.     

Dental arch widths and mandibular-maxillary base widths in Class II malocclusions between early mixed and permanent dentitions

The aim of the study was to analyze the transverse morphology and development of the dental arches and skeletal mandibular-maxillary bases in untreated Class II malocclusions. Using the records of the Belfast Growth Study, a Class II division 1 group (II/1) and a Class II division 2 group (II/2) were compared with a Class I group and a control group with good occlusion. On posteroanterior cephalograms, maxillary skeletal base width and bigonial and biantegonial widths were determined at two-year intervals between seven and 15 years. Maxillary and mandibular intermolar widths were measured on the associated study casts. As a result, maxillary skeletal base widths were smallest in the Class II/1 subjects. No statistically significant differences were found among the groups for the skeletal mandibular widths. With respect to the development of the dental arches, maxillary intermolar widths were smaller in the Class II/1 group than in the Class I and the good-occlusion groups. These group differences were present for the total period of observation, ie, seven to 15 years, and statistically significant at most ages. When the relative difference between the maxillary and the mandibular intermolar widths was examined, the Class II/1 cases were found to have the largest average difference (about -2.5 mm for boys and -1.5 mm for girls), indicating a relatively narrow maxillary arch. Less pronounced molar differences were found in the Class II/2 group. In the Class II/1 subjects the deviations in molar differences observed at 15 years of age were established already at 7 years of age and maintained during 7 and 15 years of age.     

Birth order and risk of testicular cancer

To explore the etiology of testicular cancer, cases of testicular cancer were identified among members of a cobort of Danish boys born between 1941 and 1957 (inclusive), who had attended schools in Copenhagen and Gentofte and whose school health records were contained in an archive under the supervision of the Danish Cancer Registry. One hundred and eighty-three cases of testicular cancer diagnosed before 31 December 1984 were identified; 366 controls, matched to cases by sex and age, were selected from the same cohort. Information on potential risk factors and confounders was obtained from two sources: school health records and midwife protocols, both of which were recorded prior to the diagnosis of testicular cancer in cases. Relative risks (RR) approximated by the odds ratios were calculated and, in logistic regression analyses, adjustments were done for known or suspected confounders. A decreasing risk of testicular cancer with increasing birth order was observed (P=0.020). Compared with being firstborn, being number four or more in birth order was associated with a significantly decreased RR for all testicular cancers (RR=0.3,95 percent confidence interval [CI]=0.3–0.8) and testicular seminoma (RR=0.1, CI=0.02–0.9). No association was observed between high social class and the risk of testicular cancer (RR=1.4, CI=0.8–2.3); neither was age at which the study subjects had mumps or measles related to risk of testicular cancer. No cases of mumps orchitis were observed before or during school years. A slightly increased RR for testicular cancer among boys from small families could be explained by the association between family size and birth order. The observed association between rank in birth order and the risk of testicular cancer was attributed to the reported differences in maternal estrogen levels in first cf second pregnancy, and supports the hypothesis of a tumor-initializing effect of high levels of estrogen early in a pregnancy on the developing testicular tissues.Dr Jensen, formerly Director of the Danish Cancer Registry and member of the CCC Editorial Board, died last year.     

Serum amyloid P component binds to late apoptotic cells and mediates their uptake by monocyte‐derived macrophages

Objective

Some pentraxins, such as C‐reactive protein, bind to apoptotic cells and are involved in the clearance of these cells. We undertook this study to determine whether serum amyloid P component (SAP; a pentraxin that, when deficient in mice, results in lupus‐like disease) binds to apoptotic cells and to assess the functional consequences of SAP binding for their phagocytosis by macrophages.

Methods

Human peripheral blood monocytes were isolated and cultured for 7 days to obtain monocyte‐derived macrophages. Jurkat cells were irradiated with ultraviolet B to induce apoptosis. After 4 hours, a mean ± SEM of 54.0 ± 5.1% of these cells stained with annexin V and were propidium iodide negative (early apoptotic [EA] cells). After 24 hours, 77.3 ± 2.7% of cells stained positive with both annexin V and propidium iodide (late apoptotic [LA] cells or secondary necrotic cells). EA and LA cells were incubated with fluorescein isothiocyanate–labeled SAP in the presence or absence of Ca²⁺, and binding was measured by flow cytometry. Phagocytosis was tested by incubation of macrophages with EA or LA cells in the presence of normal human serum (NHS) and quantified as a phagocytosis index (PI; number of Jurkat cells internalized by 100 macrophages). Experiments were repeated with SAP‐depleted serum and after reconstitution with increasing concentrations of SAP.

Results

The majority of LA cells did bind SAP in the presence of Ca²⁺, whereas EA cells did not. SAP depletion of NHS resulted in a 50% decrease in the PI for LA cells, and complete restoration of the PI could be demonstrated with SAP reconstitution up to 100 μg/ml. SAP depletion had no effect on phagocytosis of EA cells.

Conclusion

SAP binds to LA cells and is involved in the phagocytosis of these cells by human monocyte–derived macrophages. This may have consequences for diseases such as systemic lupus erythematosus, in which phagocytosis of apoptotic cells is decreased.