Two-year Exposure Research Articles

Predicted 25-hydroxyvitamin D in relation to incidence of breast cancer in a large cohort of African American women.

BackgroundVitamin D deficiency, which has been linked to an increased risk of colorectal cancer, is particularly common among African Americans. Previous studies of vitamin D status and breast cancer risk, mostly conducted in white women, have had conflicting results. We examined the relationship between predicted vitamin D status and incidence of breast cancer in a cohort of 59,000 African American women.MethodsParticipants in the Black Women’s Health Study have been followed by biennial mail questionnaires since 1995, with self-reported diagnoses of cancer confirmed by hospital and cancer registry records. Repeated five-fold cross-validation with linear regression was used to derive the best 25-hydroxyvitamin D (25(OH)D) prediction model based on measured 25(OH)D in plasma specimens obtained from 2856 participants in 2013–2015 and questionnaire-based variables from the same time frame. In the full cohort, including 1454 cases of incident invasive breast cancer, Cox proportional hazards models were used to compute the incidence rate ratio (IRR) for each quartile of predicted vitamin D score relative to the highest quartile. Predicted vitamin D score for each two-year exposure period was a cumulative average of predicted scores from all exposure periods up to that time.ResultsTwenty-two percent of women with measured 25(OH)D were categorized as “deficient” (<20 ng/mL) and another 25 % as “insufficient” (20–29 ng/mL). The prediction model explained 25 % of variation in measured 25(OH)D and the correlation coefficient for predicted versus observed 25(OH)D averaged across all cross-validation runs was 0.49 (SD 0.026). Breast cancer risk increased with decreasing quartile of predicted 25(OH)D, p for trend 0.015; the IRR for the lowest versus highest quartile was 1.23 (95 % confidence interval 1.04, 1.46).ConclusionsIn prospective data, African American women in the lowest quartile of cumulative predicted 25(OH)D were estimated to have a 23 % increased risk of breast cancer relative to those with relatively high levels. Preventing vitamin D deficiency may be an effective means of reducing breast cancer incidence in African American women.

Regular Aspirin Use and Risk of Non-Hodgkin Lymphoma: A Prospective Analysis in the Nurses’ Health Study

Background: There is increasing evidence that aspirin reduces the incidence and mortality of several cancers. The results of epidemiologic studies of aspirin in relation to non-Hodgkin lymphoma (NHL) however, are inconsistent, and the association appears to vary by NHL histologic subtype. We aimed to prospectively assess the association between aspirin and major subtypes of NHL in a cohort with detailed data on aspirin use.Methods: The Nurses’ Health Study (NHS) comprises 121,701 female United States licensed registered nurses who were ages 30-55 years at enrollment in 1976 and have been followed thereafter with biennial questionnaires to update medical history and personal and lifestyle information. Aspirin use was first queried in 1980. We incorporated a two-year exposure lag to minimize influence of reverse causation. Thus, “baseline” was 1982 for this analysis. We followed participants from baseline through June 2010, including all who had no baseline history of cancer or rheumatoid arthritis (RA)—a risk factor for NHL that may also affect aspirin use habits—and who completed the first questions on aspirin use. Participants were censored at the date of a cancer or RA diagnosis, or at date of death. We identified incident primary diagnoses of NHL via the follow-up questionnaires or by National Death Index follow-up. We confirmed the diagnoses and determined the histologic subtype by medical record review. Aspirin use was quantified both as cumulative average quantity (adult-strength tablets/week), and as duration of continuous regular use (years). To estimate the relative risk of NHL associated with a given quantity or duration of regular aspirin use, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) in Cox models that were stratified on calendar period and age (months) and adjusted for geographic region of residence and height. Trend tests were based on comparable multivariable models in which the medians of aspirin use variable categories were modeled as ordinal variables.Results: In 1,749,512 person-years of follow-up we identified 738 cases of NHL with available information about regular aspirin use. In the 2-year lagged analyses of regular aspirin quantity, regular aspirin use showed a suggestive positive association with risk of follicular lymphoma. In particular, women who used a cumulative average of 1 to <2, 2 to <5, or ≥5 tablets/week had a modest non-significant increased risk of follicular lymphoma compared to non-users (HR [95% CI] were 1.56 [0.84-2.91], 1.28 [0.69-2.35] and 1.64 [0.91-2.94], respectively; p-trend=0.03, based on 135 cases). No association was suggested for regular aspirin quantity with diffuse large B-cell lymphoma (DLBCL; p-trend=0.72, 114 cases), chronic lymphocytic leukemia (CLL; p-trend=0.13, 219 cases) or with NHL overall (p-trend=0.14). Duration of regular aspirin use was not associated significantly with follicular lymphoma (p-trend=0.70) or with DLBCL (p-trend=0.52), CLL (p-trend=0.32) or NHL overall (p-trend=0.45).Conclusions: Our findings of no association between regular aspirin use and NHL, other than a suggestive positive association between cumulative average quantity of use and follicular lymphoma risk, were contrary to expectation but consistent with an earlier published cohort study. The present analysis was limited in part by sparse data, especially in subtype-specific analyses. Further evaluation in a comparable cohort of men and in the two cohorts combined (where statistically appropriate) may lend further insights. If confirmed in other large populations, the findings in the NHS suggest that aspirin use may be only associated with risk of follicular lymphoma, consistent with the view that there is some etiologic heterogeneity across major subtypes of NHL. DisclosuresZhang:Takeda Pharmaceuticals Inc: Employment.

THU0141 Low-Dose Prednisolone Treatment of Early Rheumatoid Arthritis Was Associated with Increased Risk of Cerebrovascular but not Coronary Artery Events: Ten Year Follow-Up of A Two-Year Randomized Trial

BackgroundIn the last years, glucocorticoids given in addition to disease-modifying anti-rheumatic drugs (DMARDs) have been used as disease modifying therapy. The potential cardiovascular (CV) risk of exposure to GCs is...

Full-Scale Hot Cell Test of an Acoustic Sensor Dedicated to Measurement of the Internal Gas Pressure and Composition of a LWR Nuclear Fuel Rod

A full-scale hot cell test of the internal gas pressure and composition measurement by an acoustic sensor was carried out successfully between 2008 and 2010 on irradiated fuel rods in the LECA-STAR facility at CADARACHE Centre. The acoustic sensor has been specially designed in order to provide a non-destructive technique to easily carry out the measurement of the internal gas pressure and gas composition (mainly Helium-Xenon mixture, with a small amount of Krypton) of a LWR nuclear fuel rod. This sensor has been achieved in 2007 and is now covered by an international patent. We performed the gas characterisation contained in irradiated fuel rods. The acoustic method accuracy is now ±5 bars on the pressure measurement result and {±}0.3% on the evaluated gas composition. The results of the acoustic method were compared to puncture results (destructive sampling). Another significant conclusion is that the efficiency of the acoustic method is not altered by the irradiation time, and possible modification of the cladding properties. The sensor-operating characteristics have not been altered by a two-year exposure in the hot cell conditions. These results make it possible to demonstrate the feasibility of the technique on irradiated fuel rods. The transducer and the associated methodology are now operational.

Inhalation carcinogenicity and toxicity of 1,2-dichloropropane in rats

The toxicity and carcinogenicity of 1,2-dichloropropane (DCP) were examined by inhalation exposure of male and female F344 rats to DCP for either 13 wk or 2 years. In the 13-wk study, the DCP concentrations used were 125, 250, 500, 1000, or 2000 ppm (v/v), and in the 2-year study the DCP concentrations were 80, 200, or 500 ppm (v/v). Thirteen-week exposure to DCP induced hyperplasia in the respiratory epithelium and atrophy of the olfactory epithelium at 125 ppm and above. At the higher levels of exposure, hemolytic anemia and lesions of liver and adrenal gland were observed. Two-year exposure to DCP significantly increased incidences of papilloma in the nasal cavity of male and female rats exposed to 500 ppm DCP. In addition, three cases of esthesioneuroepithelioma were observed in the DCP-exposed male rats. Total nasal tumors increased in a concentration-dependent manner. Hyperplasia of the transitional epithelium and squamous cell hyperplasia, both of which were morphologically different from the hyperplasia of the respiratory epithelium observed in the 13-wk exposure study, occurred in a concentration-dependent manner; these lesions are considered to be preneoplastic lesions. Atrophy of the olfactory epithelium, inflammation of the respiratory epithelium, and squamous cell metaplasia were also seen in the 2-year study. These results demonstrate that DCP is a nasal carcinogen in rats. Lifetime cancer risks for humans exposed to DCP in the ambient air and work environment were quantitatively estimated, using both nonthreshold and threshold approaches, with the data obtained from the 2-year study.

Problems in predicting 137Cs levels in lake waters of eastern Fennoscandia

With regard to data on two-year exposure of Chernobyl-derived 137Cs in lakes with average depths ranging from 2 to 15 m, contamination of lake waters has been estimated using a sorption-diffusion model with 137Cs distribution and diffusion coefficients of 4000 l/kg and 1.0 × 10−7 cm2, respectively.

Reproductive Lesions in Female Harlan Sprague-Dawley Rats Following Two-Year Oral Treatment with Dioxin and Dioxin-like Compounds

Results from previously published animal studies suggest that prenatal and postnatal exposure to dioxin and dioxin-like compounds (DLCs) may profoundly affect the reproductive system of both sexes via endocrine disruption. In the present work, we evaluate the toxicity and carcinogenicity of various DLCs, with an emphasis on their effect on the reproductive organs, induced by chronic exposure of female adult Harlan Sprague-Dawley rats. This investigation represents part of an initiative of the National Toxicology Program to determine the relative potency of chronic toxicity and carcinogenicity of polychlorinated dioxins, furans, and biphenyls. For fourteen, thirty-one, or fifty-three weeks or for two years, animals were administered by gavage 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 3,3',4,4',5-pentachlorobiphenyl (PCB126); 2,3,4,7,8-pentachlorodibenzofuran (PeCDF); 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153); 2,3',4,4',5-pentachlorobiphenyl (PCB118); a tertiary mixture of TCDD, PCB126, and PeCDF; a binary mixture of PCB126 and 153; or a binary mixture of PCB126 and PCB118. The ranges of treatment-related changes in the reproductive system included chronic active inflammation in the ovary that occurred in the 1,000 and 3,000 microg/kg core groups (two-year exposure) of PCB153 and in the 300 ng/3,000 microg/kg core group of binary mixture of PCB126 and PCB153. Increases in the incidence of acute and/or chronic active inflammation of the uterus were observed in all dosed groups, including the stop-exposure group (withdrawal after thirty-week exposure) of PeCDF and the 1,000 microg/kg and/or higher group dosed with PCB153. The incidence of cystic endometrial hyperplasia was marginally increased in the 92 PeCDF ng/kg group at two years. The incidence of squamous metaplasia was significantly increased in the 44 ng/kg and higher dose group, including the stop-exposure group. The incidence of uterine squamous cell carcinoma was significantly or marginally increased in the 6 ng/kg core and 100 ng/kg stop-exposure groups of TCDD and in the 300 ng/300 microg/kg core group that received the binary mixture of PCB126 and 153. The incidence of uterine carcinoma was marginally increased in the 92 ng/kg PeCDF group at two years and clearly increased in the 1,000 and 4,600 microg/kg PCB118 core group and the 4,600 microg/kg stop group. In the studies of PCB 126, the tertiary mixture, and the binary mixture of PCB126 and PCB118, no increased incidence of any change occurred in the reproductive systems. The range of changes seen with the different compounds suggests that more than one mechanism may have been involved in promoting the female reproductive pathology.

Measurement of Neutrino Oscillations with the MINOS Detectors in the NuMI Beam

This Letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum-mechanical oscillations of neutrino flavor with mass splitting |Deltam2| = (2.43+/-0.13) x 10(-3) eV2 (68% C.L.) and mixing angle sin2(2theta) > 0.90 (90% C.L.). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight: namely, neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard-deviation levels, respectively.

Effect of the marine environment on reinforced concrete durability in Iberoamerican countries: DURACON project/CYTED

This work presents some of the results from the project: “Effect of the environment on reinforcement durability” (DURACON) in its first two-years period, which investigates the influence of urban and marine meteorochemical parameters on the performance of reinforced concrete structures. The results presented in this investigation are from 21 marine test sites only (no urban environments are included), distributed among 11 countries (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal and Venezuela). The environment was evaluated using ISO Standard 9223 and the concrete was characterized by measuring compressive strength, elastic modulus, total and effective porosity, chloride permeability according to ASTM standards, as well as the effective porosity and resistance to water absorption using the Fagerlund method. To that effect, concrete specimens (with and without reinforcement) were prepared for electrochemical and physical/mechanical/chemical tests using the existing materials in each participating country, following strict procedures which enabled the preparation of similar concrete samples. Two water/cement (w/c) ratios (0.45 and 0.65) were selected, where the concrete with 0.45 w/c ratio had to have a minimum cement content of 400 kg/m 3 and the one with 0.65 w/c ratio a compressive strength of 210 kg/cm 2. Type I Portland cement, siliceous sand, and crushed rock as coarse aggregates (13-mm maximum nominal size) were used. After a one-year exposure, the results of the corrosion potentiality and probability analysis of the reinforcement in the different test stations showed that, for marine atmospheres, the most aggressive environment to induce steel corrosion was at Portugal’s Cabo Raso station, and the least aggressive one was at Chile’s Valparaíso station. These results are comparable with the ones found using electrochemical measurements, after a two-year exposure.

ブチル 2,3-エポキシプロピル エーテルの長期吸入暴露による鼻腔発がん

ブチル 2,3-エポキシプロピル エーテルの長期吸入暴露による鼻腔発がん

The wider social environment and changes in self-reported quality of life in the transition from late childhood to early adolescence: a cohort study

BackgroundNeighbourhood socioeconomic disadvantage and social capital have been associated with adolescent well-being, but the majority of studies were cross-sectional, and the time window over which the neighbourhood may impact on development is unknown. Therefore, the contribution of the neighbourhood environment to adolescents' quality of life and the course of these effects during the period of transition from childhood to early adolescence was examined.MethodsA cohort of adolescents living in Maastricht (The Netherlands), with a mean age of 11.2 years at baseline and of 13.5 years at follow-up was followed. Adolescents who responded both at baseline and at follow-up were included in the analysis (n = 475). Multilevel regression analyses estimated neighbourhood effects while controlling for individual-level effects. Neighbourhood-level socioeconomic and social capital variables, individual-level confounders, and baseline values of the outcome measures were included in the models.ResultsNone of the neighbourhood factors was associated with changes in general health or mental health over the two-year period. However, two-year exposure to greater disparity between individual level socioeconomic status on the one hand and neighbourhood level of socioeconomic status on the other (e.g. high socioeconomic status adolescents living in deprived neighbourhoods and vice versa) negatively impacted on self-esteem and satisfaction.ConclusionThe neighbourhood environment per se does not contribute to change in quality of life during the transition to early adolescence. However, adolescents living in families whose socioeconomic status deviates from the mean level of neighbourhood socioeconomic deprivation may be negatively affected.

Predoctoral Dental Student Evaluation of American Academy of Pediatric Dentistry's Caries‐Risk Assessment Tool

The purpose of this study was to determine predoctoral dental student evaluation of the American Academy of Pediatric Dentistry's Caries-Risk Assessment Tool (CAT) for children. Dental students were introduced to the CAT instrument as part of their didactic pediatric dentistry curriculum. These students were later encouraged to use the CAT instrument for determining caries risk in their pediatric patients. Following a two-year exposure to the CAT instrument, dental students completed an anonymous seven-item evaluation of the instrument at the end of their primary clinical experience in pediatric dentistry. The students were asked to score each item on a five-point scale ranging from strongly agree (#5) to neutral (#3) to strongly disagree (#1). Ninety-seven percent of eligible students completed the CAT evaluation questionnaire. Most students agreed that the CAT instrument was easy to understand (86 percent), simple to apply (76 percent), useful for prescribing radiographs (76 percent), and useful for determining preventive procedures (84 percent). Eighty percent of them indicated that they were likely to use the CAT instrument in their clinical practice. In conclusion, student acceptance of the CAT instrument indicates that it may educate predoctoral dental students regarding caries risk assessment in children.

Variation in steel-mortar bond strength and microstructure in cathodically protected specimens after two-year exposure

Variation in steel-mortar bond strength and microstructure in cathodically protected specimens after two-year exposure

Seasonal variations in corrosion rate and runoff rate of copper roofs in an urban and a rural atmospheric environment

This paper summarizes the results from an extensive field exposure program implemented to study possible seasonal dependencies of copper corrosion rates and runoff rates. Two-year exposures in one urban and one rural environment were performed at four different starting seasons. An extensive multi-analytical approach was undertaken of all exposed samples. Seasonal differences in corrosion product formation was observed during the first month of exposure and attributed mainly to differences in relative humidity conditions. Seasonal differences in corrosion rate at the rural site could be discerned throughout the whole two-year exposure, again, mainly attributed to differences in relative humidity. No seasonal effect could be observed at the urban site indicating that other parameters influenced the corrosion kinetics at this site. While corrosion rates exhibit a continuous decrease with exposure time, the yearly runoff rates are independent of time. Depending on starting months the yearly copper runoff rates ranged from 1.1 to 1.7 g m −2 y −1 for the urban site, and from 0.6 to 1.0 g m −2 y −1 for the rural site. These seasonal variations were primarily attributed to differences in precipitation quantity and environmental characteristics. Runoff rates are significantly lower than corrosion rates as long as the adhering copper patina is growing with exposure time. A full risk assessment requires not only information on the total amount of copper in the runoff, but also on its chemical speciation. Under present conditions, 70–90% of all copper in runoff water collected immediately after leaving the surface is present as the most bioavailable form, the hydrated cupric ion, Cu(H 2O) 6 2+.

Variation in steel-mortar bond strength and microstructure in cathodically protected specimens after two-year exposure

Steel embedded in concrete passivate due to the formation of an oxide film that may be broken by exposure to aggressive environments. In such cases, reinforcing bars need to be cathodically protected.

The Effects of Simple Interventions on Tooth Mortality: Findings in One Trial and Implications for Future Studies

The purpose of this report was to use a particular clinical trial, the Preventive Geriatric Trial (PGT), as a starting point to discuss whether treatment efficacy can be evaluated by means of tooth mortality. In the PGT, 296 subjects were recruited and randomly assigned to five treatment groups: (1) usual procedures (UP); (2) UP + a cognitive-behavioral intervention (CB); (3) UP + CB + weekly chlorhexidine rinse (CHX); (4) UP + CB + CHX + semi-annual fluoride varnish (F); and (5) UP + CB + CHX + F + semi-annual prophylaxis, including scaling (P). Exploratory analyses revealed that tooth mortality after the 1st year was lower in treatment groups 3, 4, and 5 than in groups 1 and 2. A one-year exposure resulted in a 45% reduction in tooth mortality (p < 0.05); a two-year exposure resulted in a 59% reduction (p-value < 0.04). The PGT findings suggested that it is possible to design trials based on clinically relevant endpoints, such as tooth mortality. For the detection of moderate treatment effects, such trials could take the form of Large, Simple Trials (LST), where many subjects are recruited with minimally restrictive entry criteria, and data are collected only on essential baseline characteristics and tooth mortality. LSTs have provided "reliable answers to important clinical questions" for other chronic diseases, and several arguments suggest that they could play a similar critical role in dental research: (1) Periodontitis and caries are among the most common and costly chronic diseases affecting humans, and the identification of even moderately effective treatments by LSTs can have a large socio-economic impact; (2) the identification of low-cost widely practicable treatments that lend themselves to be investigated in LSTs is likely to benefit more people than the identification of high-cost complex treatments; and (3) tooth mortality is simple to assess and more relevant than the unvalidated surrogate endpoints that have largely failed for more than 20 years to provide reliable answers to certain controversial issues regarding treatment efficacy. The cost of not reliably establishing the safety and the efficacy of treatments may be far greater than the cost of conducting LSTs.

Neural network approach to obtain the primary proton flux at the knee from a hybrid-experiment of EC and AS array in Tibet

A hybrid experiment of emulsion chamber and air shower array will be started from 1996 at Yangbajing (4300 m above sea level) in Tibet, aimed at obtaining the primary proton flux around the knee energy region. In order to examine a classification power of proton induced showers from others using this apparatus, we have done an extensive Monte Carlo simulation in which the observation conditions were adequately taken into account. For this purpose, a multiple layered feed forward neural network was used as a classifier to select proton and helium induced shower events preferentially. It is shown that the separation of protons and the proton-helium group from all events can be achieved with an efficiency of 80–85%. The performance of the experiment under a two-year exposure is discussed.

Effects of elevated CO2 concentration on leaf characteristics and photosynthetic capacity of beech (Fagus sylvatica) during the growing season

Two-year-old beech (Fagus sylvatica L.) saplings were planted directly in the ground at high density (100 per m(2)), in an experimental design that realistically mimicked field conditions, and grown for two years in air containing CO(2) at either ambient or an elevated (ambient + 350 ppm) concentration. Plant dry mass and leaf area were increased by a two-year exposure to elevated CO(2). The saplings produced physiologically distinct types of sun leaves associated with the first and second growth flushes. Leaves of the second flush had a higher leaf mass per unit area and less chlorophyll per unit area, per unit dry mass and per unit nitrogen than leaves of the first flush. Chlorophyll content expressed per unit nitrogen decreased over time in plants grown in elevated CO(2), which suggests that, in elevated CO(2), less nitrogen was invested in machinery of the photosynthetic light reactions. In early summer, the photosynthetic capacity measured at saturating irradiance and CO(2) was slightly but not significantly higher in saplings grown in elevated CO(2) than in saplings grown in ambient CO(2). However, a decrease in photosynthetic capacity was observed after July in leaves of saplings grown in CO(2)-enriched air. The results demonstrate that photosynthetic acclimation to elevated CO(2) can occur in field-grown saplings in late summer, at the time of growth cessation.

Two-Year Inhalation Exposure of Female and Male B6C3F1 Mice and F344 Rats to Chlorine Gas Induces Lesions Confined to the Nose

Two-Year Inhalation Exposure of Female and Male B6C3F1 Mice and F344 Rats to Chlorine Gas Induces Lesions Confined to the Nose

Two-Year Results of Long-Term, Copper-Nickel Sheathed Piling Studies

Abstract A series of cylindrical steel piling sheathed with copper alloy UNS C70600 were exposed in Banks Channel at Wrightsville Beach, North Carolina in 1983 to provide long-term base line data on the corrosion and biofouling behavior of insulated and directly welded sheathing techniques. After a two-year exposure, one series of piling were removed and evaluated. Insulated sheathed piling exhibited a minimal amount of biofouling attachment and unprotected piling with directly welded sheathing showing no accelerated corrosion of the adjacent steel. This paper presents the techniques used and the results after the first two years of exposure.