Infection dynamics and virus-induced apoptosis in cell culture-based influenza vaccine production—Flow cytometry and mathematical modeling

Cell culture-based influenza vaccine manufacturing is of growing importance. Depending on virus strains, differences in infection dynamics, virus-induced apoptosis, cell lysis and virus yields are observed. Comparatively little is known concerning details of virus–host cell interaction on a cellular level and virus spreading in a population of cells in bioreactors. In this study, the infection of MDCK cells with different influenza A virus strains in lab-scale microcarrier culture was investigated by flow cytometry. Together with the infection status of cells, virus-induced apoptosis was monitored. A mathematical model has been formulated to describe changes in the concentration of uninfected and infected adherent cells, dynamics of virus particle release (infectious virions, hemagglutinin content), and the time course of the percentage composition of the cell population.     

Thyroid hormones are associated with exposure to persistent organic pollutants in aging residents of upper Hudson River communities

The aim of this study was to evaluate the association between persistent organic pollutants (POPs) and thyroid hormones in an aging population. Forty-eight women and 66 men, aged 55–74 years and living in upper Hudson River communities completed a questionnaire and provided blood specimens. Serum was analyzed for thyrotropin (thyroid stimulating hormone, TSH), free (fT₄) and total thyroxine (T₄), total triiodothyronine (T₃), and for POPs. POPs included 39 polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) determined by gas chromatography with electron capture detection (GC–ECD), and nine polybrominated diphenyl ethers (PBDEs) determined by high-resolution gas chromatography with high-resolution mass spectrometry detection (HRGC–HRMS). Multivariable linear regression analysis was used to evaluate associations between thyroid hormones and sums of POPs, adjusted for covariates and stratified by sex. Effects were expressed as differences in thyroid hormone levels associated with a doubling in the level of exposure. Among women, DDT + DDE increased T₄ by 0.34 μg/dL (P = 0.04) and T₃ by 2.78 ng/dL (P = 0.05). Also in women, sums of PCBs in conjunction with PBDEs elicited increases of 24.39–80.85 ng/dL T₃ (P < 0.05), and sums of PCBs in conjunction with DDT + DDE elicited increases of 0.18–0.31 μg/dL T₄ (P < 0.05). For men estrogenic PCBs were associated with a 19.82 ng/dL T₃ decrease (P = 0.003), and the sum of estrogenic PCBs in conjunction with DDT + DDE elicited an 18.02 ng/dL T₃ decrease (P = 0.04). Given age-related declines in physiologic reserve, the influence of POPs on thyroid hormones in aging populations may have clinical implications and merits further investigation.     

Effects of Androgen Disruption by DDE on the Development and Functioning of the Immune System in Japanese Quail

We hypothesized that immunosuppression in birds that is caused by exposure to antiandrogenic chemicals occurs mainly through disruption of the development of the androgen-sensitive avian lymphoid organ, the bursa of Fabricius. Injections of 20.0 or 40.0 μg of p,p′-DDE [ethylene, 1,1-dichloro-2,2-bis(p-chlorophenyl)], an antiandrogen, were administered at embryonic day 1. Bursas from only chicks treated with DDE were larger than, had fewer follicles, and exhibited vacuolization within follicles compared with controls; spleens were unaffected. No differences in either immune response test were observed. This study demonstrates that the bursa may play a role in androgen-active endocrine disrupting chemical-induced immunosuppression.     

人体内DDE含量与人类乳腺癌关系的Meta分析

目的：综合分析人体内二氯二苯二氯乙烯(DDE)含量与女性乳腺癌的关系。方法：运用Meta分析方法，综合10篇DDE与人类乳腺癌关系的病例对照研究报告，分析DDE含量在病例及对照组间的差异以及DDE含量与乳腺癌的剂量效应关系。结果：病例与对照两组对象体内DDE总标化差ds=0．1228，校正ds95％可信区间为(-1．0514～1．2970)；DDE与乳腺癌患病风险的趋势1．017，OR95％可信区间为(-1．0514～1．2970)；开展研究的国家、DDE的生物材料来源以及对照组的选择均影响文献的同质性。结论：DDE与乳腺癌的关系尚需流行病学研究进一步验证；在大量使用该有机氯农药的地区，DDE可能是乳腺癌的危险因子；在进行相关研究时，应选择血浆作为DDE暴露测量的生物材料。     

Birth defects risk associated with maternal sport fish consumption: potential effect modification by sex of offspring

Contaminated sport fish consumption may result in exposure to various reproductive and developmental toxicants, including pesticides and other suspected endocrine disruptors. We investigated the relation between maternal sport fish meals and risk of major birth defects among infants born to members of the New York State (NYS) Angler Cohort between 1986 and 1991 (n=2237 births). Birth defects (n=125 cases) were ascertained from both newborn medical records and the NYS Congenital Malformations Registry. For sport fish meals eaten during pregnancy, the odds ratio (OR) for all major malformations combined was slightly elevated for < or =1 meal/month (OR=1.26, 95% confidence interval (CI): 0.84, 1.89) and > or =2 meals/month (OR=1.51, CI=0.74, 3.09), with no meals during pregnancy as the reference category. Higher ORs were consistently observed among male offspring compared with females. For > or =2 meals/month, the risk for males was significantly elevated (males: OR=3.01, CI: 1.2, 7.5; females: OR=0.73, CI: 0.2, 2.4). Exposure during pregnancy and effect modification by infants sex could be important considerations for future studies of birth outcomes associated with endocrine disruptors.     

Environmental pathways of exposure to DDT for children living in a malarious area of Chiapas, Mexico

Considering that DDT was used for control of malaria vectors in Mexico, and taking into account that the information regarding children in areas exposed to DDT is scarce, we started a research program for the assessment of health effects in children living in DDT sprayed areas. In this first report, we present information about pathways of exposure in two communities with a different history of exposure to DDT. Environmental pathways such as outdoor soils, indoor soils and household dust were assessed comparing a community highly exposed to DDT (HEC) and a community less exposed to DDT (LEC). Also in these communities, a cross-sectional study of 60 children (30 in each community) aged 6--12 years was conducted. Tests included a questionnaire and the measurement of whole blood DDT and DDE. Results show that in children living in the HEC, DDT and DDE mean blood levels were higher (15.9+/-8.2 and 58.2+/-29.2 microg/L) than in the LEC (1.9+/-3.6 and 9.2+/-5.7 microg/L) (P<0.01). Concentrations of DDT, DDE and DDD in indoor soil were higher in the HEC (10.3+/-10; 4.9+/-5.8; and 4.4+/-9.1mg/kg) than in the LEC (0.3+/-0.3; 0.04+/-0.06; and 0.03+/-0.04 mg/kg) (P<0.001). Similar results were obtained for outdoor soils; in the HEC, levels for DDT, DDE and DDD were 3.1+/-3.0; 1.0+/-0.8; and 0.3+/-0.2mg/kg; whereas levels in the LEC were 0.16+/-0.2; 0.02+/-0.03; and 0.02+/-0.03 mg/kg (P<0.001). High concentrations of DDT, DDE, and DDD were obtained in samples of indoor dust collected from the walls in the HEC (17.5+/-10.0; 5.5+/-6.2; and 9.8+/-16.8 mg/kg); levels in the LEC were lower (0.6+/-0.9; 0.07+/-0.1; and 0.05+/-0.07 mg/kg) (P<0.001). We did not find any correlation between blood levels of DDE and total DDT with environmental concentrations but there levels increased in LEC and HEC as the frequency of fish consumption increased (P<0.01).     

DDT-induced oxidative damage in human blood mononuclear cells

Recent work indicates that DDT and its metabolites induce apoptosis in different cellular types. However, the mechanism by which DDT generates apoptosis has not been elucidated. In this study, our data demonstrate that the apoptosis induction by DDT and its metabolites in human peripheral blood mononuclear cells (PBMC) is preceded by an increase in the levels of reactive oxygen species (ROS). Cells isolated from healthy individuals were incubated for different intervals of time (0-24 h) and in the presence of increasing concentrations of p'p-DDT, p'p-DDE, or p'p-DDD (0-80 microg/ml). The induction of oxidative stress was then determined by flow cytometry, using the compound 2',7'-dichlorofluorescein diacetate. The control level of ROS was 4.46+/-0.96 IFM, for DDT- and DDD-treated cells we obtained a 19.0-fold increment, whereas for DDE, the increment was 25-fold. ROS induction by DDT and DDE was observed after 1 h of incubation, while for DDD such levels began to be detected at 3 h of incubation; a maximum effect on the ROS production for the three compounds was found at 6 h of treatment. A significant level of ROS was induced by DDT, DDE, and DDD only at 60 and 80 microg/ml. Finally, to find an association between generation of ROS and apoptosis induction, cells incubated with DDT, DDE, and DDD were evaluated for apoptosis induction and generation of oxidative stress. Our results show that an increase in ROS was accompanied by apoptosis of PBMC in vitro. Moreover, N-acetyl-L-cysteine significantly inhibits the apoptosis induction.     

DDT serum concentration and menstruation among young Chinese women

High DDE and DDT concentrations were found to be associated with shortened menstrual cycle length in Laotian immigrants to the United States. We examined this issue in a sample of young Chinese women. A total of 60 women aged 20-24 years were enrolled in three maternal and child health clinics (20 from urban, 20 from suburban, 20 from rural) in Shanghai, China, and vicinity, in 1998. Of these women, 47 who did not use hormonal contraceptives and had valid menstrual cycle characteristics were included in the analysis for associations among serum DDE and DDT concentration and menstrual cycle length, duration of menses, and heaviness of menstrual flow. In univariate analysis, higher p,p'-DDE concentration was associated with longer menstrual cycle length (0.66 day per 10 microg/L, 95% confidence interval [CI]: 0.21, 1.11 day). With adjustment for age, body mass index, education, occupation, and resident location, the estimate was 0.42 day (95% CI: -0.35, 1.19 day). p,p'-DDE was not associated with duration of menses or heaviness of menstrual flow. Neither p,p'-DDT nor o,p'-DDT were associated with menstrual cycle length, duration of menses or heaviness of menstrual flow. The study largely suggests no association between DDE and DDT concentrations and menstrual cycle characteristics in young Chinese women, though the weak-to-no correlation of DDE with menstrual cycle length merits further study.     

Biomonitoring of mercury and persistent organic pollutants in Michigan urban anglers and association with fish consumption

The 32-mile Detroit River and surrounding tributaries have been designated as a Great Lakes Area of Concern due to pollution from decades of municipal and industrial discharges, sewer overflows and urban development. Key pollutants in fish samples from the Detroit River include mercury, polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), dioxins and furans. A biomonitoring study was conducted to assess exposures to these persistent toxic substances in Detroit urban shoreline anglers who may be at high exposure risk due to consumption of locally caught fish. Using a modified venue-based sampling approach, 287 adult shoreline anglers along the Detroit River were recruited and participated in the program. Study participants provided blood and urine specimens and completed a questionnaire following informed consent. We examined percentile estimates for total blood mercury, PCBs, DDE, and dioxin-like total toxic equivalency (TEQ) concentrations among study participants. Multiple linear regression was used to identify important predictors of contaminant concentrations. Participants consumed a median of 64 Detroit River caught fish meals in the past year. The Detroit urban anglers’ median total blood mercury concentrations was 3.2 times higher than that for the general adult U.S. population. PCB concentrations among the Detroit anglers aged 18–39 years were higher than the U.S. population of the same race/ethnicity. Elevated levels of DDE and total TEQ concentrations were not observed in the cohort. Eating more locally caught fish was associated with higher total blood mercury and serum PCB concentrations. The biomonitoring data served to inform public health officials and help guide environmental public health actions to reduce harmful exposures.     

Biomonitoring equivalents for DDT/DDE

Biomonitoring Equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline such as a reference dose (RfD) or tolerable daily intake (TDI). BE values can be used as a screening tool for the evaluation of population-based biomonitoring data in the context of existing risk assessments. This study reviews available health based risk assessments and exposure guidance values for DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, CAS #50-29-3) and related metabolites and degradation products DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane, CAS #72-55-90) and DDD (1,1-dichloro-2,2-bis(p-chloro-phenyl)ethane) based on both non-cancer and cancer risk assessments from the Food and Agriculture Organization/World Health Organization (FAO/WHO), the United States Environmental Protection Agency (US EPA), and other organizations. Laboratory data on distribution and toxicokinetics of DDT and metabolites and estimates of human elimination half-lives were used to estimate BE values (lipid-adjusted blood, serum, or plasma concentrations) corresponding to the various non-cancer exposure guidance values and cancer risk-specific doses. The BE values based on non-cancer risk assessments range from 5000 to 40,000ng/g lipid for the sum of DDT, DDE, and DDD. The BE values corresponding to a 1E-05 cancer risk level for DDT and DDE based on the US EPA assessment are 300 and 500ng/g lipid, respectively. Sources of uncertainty relating to both the basis for the BE values and their use in evaluation of biomonitoring data are discussed. The BE values derived here can be used as a screening tools for evaluation of population biomonitoring data for DDT and related compounds in the context of the existing risk assessment and can assist in prioritization of the potential need for additional risk assessment efforts for DDT relative to other chemicals.