Traffic-related air pollution and childhood acute leukemia in Oklahoma

Lipase-triggered drug release from BCL2 inhibitor ABT-199-loaded nanoparticles to elevate anti-leukemic activity through enhanced drug targeting on the mitochondrial membrane

Selective BCL2 inhibitor ABT-199 has been approved to treat hematological malignancies including acute myeloid leukemia (AML). However, acquired drug resistance and severe side effects occur after extended treatment limiting the clinical usage of ABT-199. Here, we successfully encapsulated pure ABT-199 in amphiphilic mPEG-b-PTMC₁₆₉ block copolymer, forming mPEG-b-PTMC₁₆₉@ABT-199 nanoparticles (abbreviated as PEG-ABT-199), which presented better aqueous dispersion and higher efficiency of loading and encapsulation than pure ABT-199. We then compared the anti-leukemic ability of pure ABT-199 and PEG-ABT-199 in vitro and in vivo. PEG-ABT-199 had a lower IC50 value compared with pure ABT-199 in MV4-11 and MOLM-13 cell lines. In addition, PEG-ABT-199 significantly induced apoptosis and decreased colony number than pure ABT-199. Most importantly, PEG-ABT-199 markedly reduced leukemic burden, inhibited the infiltration of leukemic blasts in the spleen, and extended the overall survival (OS) in MLL-AF9-transduced murine AML compared with free ABT-199. Meanwhile, the blank PEG169 NP was non-toxic to normal hematopoiesis in vitro and in vivo, suggesting that PEG169 NP is a safe carrier. Mechanistically, PEG-ABT-199 enhanced mitochondria-targeted delivery of ABT-199 to trigger the collapse of mitochondrial membrane potential (MMP), the release of cytochrome c (cyt-c), and mitochondria-based apoptosis. In conclusion, our results suggest that PEG-ABT-199 has more vital anti-leukemic ability than pure ABT-199. PEG-ABT-199 has potential application in clinical trials to alleviate side effects and improve anti-leukemia ability. STATEMENT OF SIGNIFICANCE: ATB-199, an orally selective inhibitor for BCL2 protein, presents marked activity in relapsed or refractory AML, T-ALL, and CLL patients. However, ABT-199 resistance severely limits the further clinical usage because of off-target effects, non-specific toxicities, and low delivery of drugs. To reduce the side-effects and improve the solubility and bioavailability, ABT-199 was encapsulated into the amphiphilic mPEG-b-PTMC block copolymer by co-assembly method to obtain mPEG-b-PTMC@ABT-199 nanoparticles (PEG-ABT-199). PEG-ABT-199 has several advantages compared with pure ABT-199. 1.PEG-ABT-199 presents better aqueous dispersion and higher efficiencies of loading and encapsulation than pure ABT-199. 2. PEG-ABT-199 substantially enhances the anti-leukemic ability in vitro and in vivo compared with pure ABT-199. 3. PEG-ABT-199 has little effects on normal cells. 4. PEG-ABT-199 can reduce treatment cost.

Environmental Risk Factors for Childhood Cancer in an Era of Global Climate Change: A Scoping Review

INTRODUCTION

Contemporary research about environmental risk factors in an era of global climate change to inform childhood cancer prevention efforts is disjointed. Planetary pediatric providers need to establish a better understanding of how the postnatal environment influences childhood cancer. Authors conducted a scoping review of recent scientific literature with the aim of understanding the environmental risk factors for childhood cancer.

METHOD

Ovid Medline, CINAHL, and Scopus databases were searched with results limited to the English language with publication years 2010-2021. Two independent reviewers screened 771 abstracts and excluded 659 abstracts and 65 full-text articles on the basis of predefinedcriteria.

RESULTS

The scoping review identified 47 studies about environmental risk factors for childhood cancer with mixed results and limited consensus in four main categories, including air pollution, chemical exposures, radiation, and residential location.

DISCUSSION

Research by collaborative international groups of planetary health researchers about environmental risk factors is needed to inform global health policy for childhood cancer prevention efforts.

Exposure to outdoor air pollution at different periods and the risk of leukemia: a meta-analysis

The causes of leukemia remain largely unknown; our aims were to examine the association between the exposure to outdoor air pollution and leukemia risk and to explore the effect of this exposure during different periods of pregnancy and early life. We searched for all case-control and cohort studies published before February 20, 2021, which measured the risk of leukemia in relation to exposure to the air pollutants: particulate matter, benzene, nitrogen dioxide (NO₂), and nitrogen oxides (NO_x). We then carried out a meta-analysis and calculated the summary relative risks (RRs) of leukemia by using a random-effects model. The potential dose-response relationship was further explored. The results showed that the highest exposure to benzene (RR: 1.20, 95%CI: 1.06-1.35) and NO₂ (RR: 1.04, 95%CI; 1.02-1.08) were positively correlated with leukemia risk when compared to the lowest exposure categories for each air pollutant. During pregnancy, exposure to benzene in the third trimester, as well as exposure to NO₂ in the second trimester and entire pregnancy, could also increase the risk of leukemia. In the dose-response analysis, benzene exposure and NO₂ exposure were linearly associated with the risk of leukemia. Other air pollutants did not have a statistical correlation with leukemia risk. There was a certain degree of publication bias in studies on benzene. Overall, our results support a link between outdoor air pollution and leukemia risk, particularly due to benzene and NO₂. Prospero Registration Number: PROSPERO CRD42020207025.

Seasonal variations in childhood leukaemia incidence in France, 1990-2014

BACKGROUND

Several studies have addressed the potential seasonality of childhood acute leukaemia (AL) without conclusive results. Using data from the National Registry of Childhood Cancers over 1990-2014 in mainland France, we investigated the seasonal variations in childhood AL taken together, and lymphoblastic (ALL) and myeloid (AML) leukaemia separately.

METHODS

Assuming constant variations over 1990-2014, we used a Poisson regression model to evaluate variations in standardized incidence ratios (SIRs) by month of birth or diagnosis. A scan method for temporal cluster detection was used to identify windows of several consecutive months with high or low SIR. The yearly reproducibility of the observed monthly variations was then evaluated.

RESULTS

We included 11,528 AL, of which 9493 ALL and 1,843 AML. No seasonal variation was detected for ALL. With a clear seasonal pattern, differences in AML incidence rates were evidenced between January-April and May-December birth periods (SIR = 0.85, 95% CI 0.77-0.94 and SIR = 1.07, 95% CI 1.01-1.14, respectively). AML incidence variations by month of diagnosis were less clear-cut.

CONCLUSION

Based on a large number of cases from a high-quality registry, we did not evidence any seasonality in ALL incidence rates but evidenced seasonal variations in AML incidence rates by month of birth.

Ambient ultrafine particle concentrations and incidence of childhood cancers

BACKGROUND

Ambient air pollution has been associated with childhood cancer. However, little is known about the possible impact of ambient ultrafine particles (<0.1 μm) (UFPs) on childhood cancer incidence.

OBJECTIVE

This study aimed to evaluate the association between prenatal and childhood exposure to UFPs and development of childhood cancer.

METHODS

We conducted a population-based cohort study of within-city spatiotemporal variations in ambient UFPs across the City of Toronto, Canada using 653,702 singleton live births occurring between April 1, 1998 and March 31, 2017. Incident cases of 13 subtypes of paediatric cancers among children up to age 14 were ascertained using a cancer registry. Associations between ambient air pollutant concentrations and childhood cancer incidence were estimated using random-effects Cox proportional hazards models. We investigated both single- and multi-pollutant models accounting for co-exposures to PM_2.5 and NO₂.

RESULTS

A total of 1,066 childhood cancers were identified. We found that first trimester exposure to UFPs (Hazard Ratio (HR) per 10,000/cm³ increase = 1.13, 95% CI: 1.03-1.22) was associated with overall cancer incidence diagnosed before 6 years of age after adjusting for PM_2.5, NO₂, and for personal and neighborhood-level covariates. Association between UFPs and overall cancer incidence exhibited a linear shape. No statistically significant associations were found for specific cancer subtypes.

CONCLUSION

Ambient UFPs may represent a previously unrecognized risk factor in the aetiology of cancers in children. Our findings reinforce the importance of conducting further research on the effects of UFPs given their high prevalence of exposure in urban areas.

Residential traffic exposure and lymphohematopoietic malignancies among children in the city of São Paulo, Brazil: An ecological study

BACKGROUND

Despite widespread evidence that air pollution is carcinogenic, there is little evidence from low-middle income countries, especially related to childhood malignancies. We examined the role of traffic related pollution on lymphohematopoietic malignancies among under-14 s in Sao Paulo.

METHODS

All incident cases between 2002 and 2011 were collected from a population-based registry. Exposures were assigned on residential address at diagnosis via traffic density database (for the year 2008) and a satellite derived NO₂ land use regression model (averaged between 1997 and 2011). Incidence rate ratios (IRRs) were calculated via Poisson Regression adjusted by age, gender and socioeconomic status (SES), with additional stratification by SES.

RESULTS

A positive association between traffic and NO₂ with some lymphohematopoietic malignancies was observed with the degree of effect differing by SES. For example, lymphoid leukemia IRRs in the lower SES group were 1.21 (95 % CI: 1.06, 1.39) for traffic density and 1.38 (95 % CI: 1.13, 1.68) for NO₂. In the higher group they were 1.06 (95 % CI: 1.00, 1.14) and 1.37 (95 % CI: 1.16, 1.62).

CONCLUSION

NO₂ and traffic density were associated with Hodgkin lymphoma and lymphoid leukemia among children in São Paulo. Differing IRRs by gender and SES group indicate differences in underlying risk and/or exposure profiles.

The association between air pollution and cancers: controversial evidence of a systematic review

There are inconsistent reports on the association between air pollution and cancers. This systematic review was, therefore, conducted to ascertain the relationship between air pollution and some cancers. This is a systematic review study, which all articles published in this area were extracted from January 1, 1950 to December 31, 2018 from Web of Science, PubMed, Scopus, Cochrane Library, MEDLINE, EMBASE, Science Direct, Google scholar. Searching was performed independently by two search-method experts. The required data were extracted from the articles by an author-made questionnaire. Forty-eight articles were investigated. Evidence linking air pollution to some cancers is limited. Leukemia had the highest association with exposure to various air pollutants and bladder cancer had the lowest association. It is noteworthy that the specific type of pollutants in all studies was not specified. Based on the findings, the results are contradictory, and the role of air pollution in some cancers cannot be supported. Accordingly, studies are recommended to be performed at the individual level or multifactorial studies to specifically investigate the relationship between air pollution and these types of cancers. In this way, the role of air pollution in the incidence of these cancers can be determined more accurately.

Air pollution exposure at the residence and risk of childhood cancers in Denmark: A nationwide register-based case-control study

BACKGROUND

The etiology of childhood cancer is poorly understood. The role of environmental factors, including air pollution (AP) exposure, has been addressed previously, but results so far have been inconclusive. In this study, we investigate the association between long-term AP exposures in relation to childhood cancer subtypes in Denmark (1981-2013).

METHODS

We conducted a nationwide register-based case-control study. We identified 7745 incident cases of childhood cancers (<20 years) in the Danish Cancer Registry. Four randomly selected (cancer-free) controls were matched to each case according to sex and date of birth. We modelled concentrations of nitrogen dioxide (NO₂), fine particles (PM_2·5), and black carbon (BC) at all addresses and calculated a time-weighted average from birth to index-date with a state-of-the-art multiscale AP modelling system. We analyzed the risk of childhood cancer in conditional logistic regression models adjusted for socio-demographic variables obtained from registers at the individual and neighborhood level.

FINDINGS

The main analyses included 5045 cases and 18,179 controls. For all cancers combined, we observed odds ratios (ORs) and 95% confidence intervals (95% CI) of 0·97 (0·94, 1·01) per 10 µg/m³ NO₂, 0·89 (0·82, 0·98) per 5 µg/m³ PM_2·5, and 0·94 (0·88, 1·01) per 1 µg/m³ BC, respectively. Most notably, we observed a higher risk of Non-Hodgkin Lymphoma (NHL) with higher childhood AP exposure with ORs and 95% CIs of 1·21 (0·94, 1·55) per 10 µg/m³ NO₂, 2·11 (1·10, 4·01) per 5 µg/m³ PM_2·5, and 1·68 (1·06, 2·66) per 1 µg/m³ BC, respectively. We observed indications of increased risks for other types of childhood cancer, however, with very wide CIs including 1.

INTERPRETATIONS

The findings of this nation-wide study propose a role of AP in the development of childhood NHL, but more large-scale studies are needed.

FUNDING

NordForsk Project #75007.

Air pollution and cardiovascular disease: car sick

The cardiovascular effects of inhaled particle matter (PM) are responsible for a substantial morbidity and mortality attributed to air pollution. Ultrafine particles, like those in diesel exhaust emissions, are a major source of nanoparticles in urban environments, and it is these particles that have the capacity to induce the most significant health effects. Research has shown that diesel exhaust exposure can have many detrimental effects on the cardiovascular system both acutely and chronically. This review provides an overview of the cardiovascular effects on PM in air pollution, with an emphasis on ultrafine particles in vehicle exhaust. We consider the biological mechanisms underlying these cardiovascular effects of PM and postulate that cardiovascular dysfunction may be implicated in the effects of PM in other organ systems. The employment of multiple strategies to tackle air pollution, and especially ultrafine particles from vehicles, is likely to be accompanied by improvements in cardiovascular health.

Potential Protective and Therapeutic Roles of the Nrf2 Pathway in Ocular Diseases: An Update

Nuclear factor- (erythroid-derived 2-) like 2 (Nrf2) is a regulator of many processes of life, and it plays an important role in antioxidant, anti-inflammatory, and antifibrotic responses and in cancer. This review is focused on the potential mechanism of Nrf2 in the occurrence and development of ocular diseases. Also, several Nrf2 inducers, including noncoding RNAs and exogenous compounds, which control the expression of Nrf2 through different pathways, are discussed in ocular disease models and ocular cells, protecting them from dysfunctional changes. Therefore, Nrf2 might be a potential target of protecting ocular cells from various stresses and preventing ocular diseases.

microRNA-146a Promotes Growth of Acute Leukemia Cells by Downregulating Ciliary Neurotrophic Factor Receptor and Activating JAK2/STAT3 Signaling

PURPOSE

Acute leukemia (AL) is classified as acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). This study aimed to investigate the effect of miR-146a on childhood AL and its underlying molecular mechanisms.

MATERIALS AND METHODS

Bone marrow samples were obtained from 39 AL children and 10 non-cancer controls. The expressions of miR-146a and ciliary neurotrophic factor receptor (CNTFR) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in ALL and AML pediatric patients, as well as ALL (Jurkat) and AML (HL-60) cells. Correlations between miR-146a and clinical indicators were explored. A targeting relationship between miR-146a and CNTFR was detected by dual luciferase reporter gene assay. Cell proliferation, apoptosis, migration, and invasion of Jurkat and HL-60 cells were measured by MTT assay, flow cytometry, and transwell assay, respectively. LIF expression was detected by qRT-PCR in Jurkat and HL-60 cells. The expression of p-JAK2, JAK2, p-STAT3, and STAT3 in HL-60 cells was measured by Western blot.

RESULTS

miR-146a was increased in ALL and AML pediatric patients, while CNTFR was decreased. miR-146a expression was associated with immunophenotype, karyotype, fusion gene, and SIL-TAL1. CNTFR was a target gene of miR-146a. miR-146a could promote cell proliferation, migration, and invasion, as well as inhibit cell apoptosis in Jurkat and HL-60 cells by downregulating CNTFR. Meanwhile, miR-146a inhibited the expression of LIF and activated JAK2/STAT3 pathway by downregulating CNTFR.

CONCLUSION

miR-146a could promote the proliferation, migration, and invasion and inhibit the apoptosis of AL Jurkat and HL-60 cells by downregulating CNTFR and activating the JAK2/STAT3 pathway.

Maternal Residential Proximity to Major Roadways and the Risk of Childhood Acute Leukemia: A Population-Based Case-Control Study in Texas, 1995-2011

Acute leukemia is the most common pediatric malignancy. Some studies suggest early-life exposures to air pollution increase risk of childhood leukemia. Therefore, we explored the association between maternal residential proximity to major roadways and risk of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Information on cases with acute leukemia (n = 2030) was obtained for the period 1995–2011 from the Texas Cancer Registry. Birth certificate controls were frequency matched (10:1) on birth year (n = 20,300). Three residential proximity measures were assessed: (1) distance to nearest major roadway, (2) residence within 500 meters of a major roadway, and (3) roadway density. Multivariate logistic regression was used to generate adjusted odds ratios (aOR) and 95% confidence intervals (CI). Mothers who lived ≤500 meters to a major roadway were not more likely to have a child who developed ALL (OR = 1.03; 95% CI: 0.91–1.16) or AML (OR = 0.84; 95% CI: 0.64–1.11). Mothers who lived in areas characterized by high roadway density were not more likely to have children who developed ALL (OR = 1.06, 95% CI: 0.93–1.20) or AML (OR = 0.83, 95% CI: 0.61–1.13). Our results do not support the hypothesis that maternal proximity to major roadways is strongly associated with childhood acute leukemia. Future assessments evaluating the role of early-life exposure to environmental factors on acute leukemia risk should explore novel methods for directly measuring exposures during relevant periods of development.

Particulate matter-associated micronuclei frequencies in maternal and cord blood lymphocytes

Studies associate particulate matter (PM) exposure with pulmonary, cardiovascular, and neurologic diseases. Elevated levels of coarse (PM10) and fine (PM2.5) PM have been reported in the Mexico City metropolitan area during the last two decades. There is limited information if these conditions affect newborns. We associated maternal exposure to PM reported by the monitoring stations considering the place of residence of each participant with the presence of genotoxic damage (cytome analysis) in maternal and umbilical cord blood (UCB) lymphocytes. Eighty-four healthy women in their last quarter of pregnancy met the inclusion criteria. Each volunteer exposure was estimated according to the average PM2.5 and PM10 levels during the last month of gestation. The micronuclei (MN) frequencies in UCB lymphocyte cultures ranged between 0 and 9. They also showed lower cell proliferation indexes than their mothers. There was a strong correlation between the maternal and the UCB MN frequency (ρ = 0.3767, P = 0.0002). Multiple regression analysis including PM10 and PM2.5 levels, maternal age, and occupation, showed a significant and positive association between UCB MN frequency and PM2.5. A statistically significant increase in the MN frequency in both maternal and UCB lymphocytes was observed in samples obtained during the dry season (higher PM levels) as compared with the MN frequency in blood samples obtained during the rainy season (lower PM levels). These results suggest that PM, mainly PM_2.5 , can cross the placenta causing DNA damage in fetal cells which may increase the potential for diseases during childhood or adult life. Environ. Mol. Mutagen. 60:421-427, 2019. © 2019 Wiley Periodicals, Inc.

Nanoparticle translocation and multi-organ toxicity: A particularly small problem

Environmental nanoparticles and manufactured nanoparticles (MNMs) can share many of the same physicochemical properties and, therefore, could have similar toxicological profiles. Inhalation of nanoparticles in air pollution has effects throughout the body; however, the potential for inhaled MNMs to affect multiple organs requires further investigation. The biological mechanisms that link nanoparticles deposition in the lung to their systemic actions remain to be established; however, the passage of nanoparticles into the blood ("translocation") represents a compelling explanation. This article highlights experimental work in animals and man showing that inhaled gold nanoparticles pass into the blood and accumulate at sites of vascular disease. The article discusses the properties of nanoparticles that could influence translocation and highlights some avenues for future research. The processes described have clear relevance, both for MNMs and sources of nanoparticles in air pollution. The authors emphasise the need for risk assessment of potential nanoparticle exposure routes that consider the multiple organ systems.

A Meta-analysis of Traffic-related Air Pollution and Risk of Childhood Leukemia

BACKGROUND

Many studies have analyzed the association between traffic-related air pollution and risk of childhood leukemia, but the results are inconsistent. Therefore, we performed this meta-analysis to investigate the association between traffic-related air pollution and risk of childhood leukemia.

METHODS

PubMed, Cochrane, and Embase databases were searched by the index words to identify eligible case-control studies, and relevant literature sources were also searched. The latest research was performed in September 2017. Odds ratio (OR) along with 95% confidence interval (95% CI) were used to analyzed the main outcomes.

RESULTS

Twenty-one case-control studies were included in the meta-analysis. The results indicated that in the studies of overall traffic density (OR: 1.01, 95% CI: 0.98-1.04), high traffic density (OR: 1.04, 95% CI: 0.91-1.17), moderate exposure to NO2 (OR: 1.02, 95% CI: 0.93-1.10), and benzene (OR: 1.04, 95% CI: 0.71-1.37), the risks of childhood leukemia incidence were higher in the case group than the control group, but no significant difference was found. In other analysis, no significant difference was observed in the risk of childhood leukemia in the 2 groups.

CONCLUSIONS

Current evidence suggests that childhood leukemia is associated with traffic density, and moderate exposure to NO2 and benzene. However, more high-quality studies are required to confirm the conclusions.

Association between Outdoor Air Pollution and Childhood Leukemia: A Systematic Review and Dose-Response Meta-Analysis

BACKGROUND

A causal link between outdoor air pollution and childhood leukemia has been proposed, but some older studies suffer from methodological drawbacks. To the best of our knowledge, no systematic reviews have summarized the most recently published evidence and no analyses have examined the dose-response relation.

OBJECTIVE

We investigated the extent to which outdoor air pollution, especially as resulting from traffic-related contaminants, affects the risk of childhood leukemia.

METHODS

We searched all case-control and cohort studies that have investigated the risk of childhood leukemia in relation to exposure either to motorized traffic and related contaminants, based on various traffic-related metrics (number of vehicles in the closest roads, road density, and distance from major roads), or to measured or modeled levels of air contaminants such as benzene, nitrogen dioxide, 1,3-butadiene, and particulate matter. We carried out a meta-analysis of all eligible studies, including nine studies published since the last systematic review and, when possible, we fit a dose-response curve using a restricted cubic spline regression model.

RESULTS

We found 29 studies eligible to be included in our review. In the dose-response analysis, we found little association between disease risk and traffic indicators near the child's residence for most of the exposure range, with an indication of a possible excess risk only at the highest levels. In contrast, benzene exposure was positively and approximately linearly associated with risk of childhood leukemia, particularly for acute myeloid leukemia, among children under 6 y of age, and when exposure assessment at the time of diagnosis was used. Exposure to nitrogen dioxide showed little association with leukemia risk except at the highest levels.

DISCUSSION

Overall, the epidemiologic literature appears to support an association between benzene and childhood leukemia risk, with no indication of any threshold effect. A role for other measured and unmeasured pollutants from motorized traffic is also possible. https://doi.org/10.1289/EHP4381.

Transplacental exposure to carcinogens and risks to children: evidence from biomarker studies and the utility of omic profiling

The factors underlying the increasing rates and the geographic variation of childhood cancers are largely unknown. Epidemiological studies provide limited evidence for a possible role in the etiology of certain types of childhood cancer of the exposure of pregnant women to environmental carcinogens (e.g., tobacco smoke and pesticides); however, such evidence is inadequate to allow definitive conclusions. Complementary evidence can be obtained from biomarker-based population studies. Such studies have demonstrated that, following exposure of pregnant mothers, most environmental carcinogens reach the fetus and, in many cases, induce therein genotoxic damage which in adults is known to be associated with increased cancer risk, implying that environmental carcinogens may contribute to the etiology of childhood cancer. During recent years, intermediate disease biomarkers, obtained via omic profiling, have provided additional insights into the impact of transplacental exposures on fetal tissues which, in some cases, are also compatible with a precarcinogenic role of certain in utero exposures. Here we review the epidemiological and biomarker evidence and discuss how further research, especially utilizing high-density profiling, may allow a better evaluation of the links between in utero environmental exposures and cancer in children.

Air Pollutants are associated with Dry Eye Disease in Urban Ophthalmic Outpatients: a Prevalence Study in China

BACKGROUND

Although previous prevalence studies of DED were reported from some countries worldwide, national data are unavailable in China. We aimed to conduct an up-to-date national survey on the prevalence of DED in China and find out the potential risk factors including air pollutant.

METHODS

23,922 eligible outpatients were recruited from ophthalmic clinics of 32 cities in China in 2013 by registration orders. The patients' demographic characteristics, history of keratorefractive surgery, diseases and medication history were collected and the daily air pollutant data in 2013. Multivariate logistic analysis was performed to identify the potential risk factors associated with DED. The association between related factors and dry eye diseases subtypes evaluated as p value and odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

Among 23,922 outpatients, the prevalence of DED was 61.57%, and that of the male patients was 57.64% and of the female was 65.32% (P < 0.0001). Multivariate logistic regression suggested that the possible risk factors for DED included: female, older age, history of keratorefractive surgery, presence of arthritis, thyroid diseases, and antihistamine, diuretic, duodenal ulcer drugs, diazepam. Air pollutants including O3, PM2.5, and SO2 were also identified as the risk factors.

CONCLUSION

The prevalence of DED among ophthalmic outpatients in China was considerably high. Age, gender, history of keratorefractive surgery, diseases, medication history, and air pollutants were associated with DED prevalence.

Silencing the PIK3CA Gene Enhances the Sensitivity of Childhood Leukemia Cells to Chemotherapy Drugs by Suppressing the Phosphorylation of Akt

PURPOSE

This study aimed to investigate the effects of PIK3CA on the sensitivity of acute B lymphocytic leukemia cells (Nalm-6 cells) to chemotherapy drugs.

MATERIALS AND METHODS

Children's normal B lymphocytes and Nalm-6 cells were cultured. Nalm-6 cells were transfected with PIK3CA siRNA (siPIK3CA group) or its negative control (PIK3CA-Control group). Normal Nalm-6 cells were named Mock group. Nalm-6 cells transfected by PIK3CA siRNA were treated with Akt inhibitor (siPIK3CA+Akti-1/2 group). mRNA and protein expression was detected by qRT-PCR and Western blot. Proliferation and sensitivity to chemotherapeutic drugs was detected by MTT assay. Cell cycle and apoptosis was explored by low cytometry. Transwell assay was performed to test invasion.

RESULTS

PIK3CA mRNA (p=0.008) and protein (p=0.006) expression was higher in Nalm-6 cells than that in normal B lymphocytes. Compared with the Mock group and PIK3CA-Control group, Nalm-6 cells of the siPIK3CA group had lower OD495 values (all p<0.05) and invasion cell numbers (p=0.03 and p=0.025), as well as a higher proportion of G0/G1 phase cells (p=0.020 and p=0.022), percentage of apoptosis (p=0.016 and p=0.022), and inhibition rate (all p<0.05). pAkt expression in the siPIK3CA group (p=0.026 and p=0.031) and siPIK3CA+Akti-1/2 group (p=0.019 and p=0.023) was lower than that in the Mock group.

CONCLUSION

PIK3CA silencing inhibited Nalm-6 cell proliferation and invasion, and promoted their apoptosis and sensitivity to chemotherapeutic drugs, potentially through regulation of the PI3K/AKT signaling pathway.

Childhood leukaemia risk and residential proximity to busy roads

BACKGROUND

Current evidence suggests that childhood leukaemia can be associated with residential traffic exposure; nevertheless, more results are needed to support this conclusion.

OBJECTIVES

To ascertain the possible effects of residential proximity to road traffic on childhood leukaemia, taking into account traffic density, road proximity and the type of leukaemia (acute lymphoid leukaemia or acute myeloid leukaemia).

METHODS

We conducted a population-based case-control study of childhood leukaemia in Spain, covering the period 1990-2011. It included 1061 incidence cases gathered from the Spanish National Childhood Cancer Registry and those Autonomous Regions with 100% coverage, and 6447 controls, individually matched by year of birth, sex and autonomous region of residence. Distances were computed from the respective participant's residential locations to the different types of roads and four different buffers. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (95%CIs), were calculated for four different categories of distance to roads.

RESULTS

Cases of childhood leukaemia had more than three-fold increased odds of living at <50 m of the busiest motorways compared to controls (OR = 2.90; 95%CI = 1.30-6.49). The estimates for acute lymphoid leukaemia (ALL) were slightly higher (OR = 2.95; 95%CI = 1.22-7.14), while estimates for cases with the same address at birth and at diagnosis were lower (OR = 2.40; 95%CI = 0.70-8.30).

CONCLUSIONS

Our study agrees with the literature and furnishes some evidence that living near a busy motorway could be a risk factor for childhood leukaemia.

Diesel exhaust exposure, its multi-system effects, and the effect of new technology diesel exhaust

Exposure to diesel exhaust (DE) from vehicles and industry is hazardous and affects proper function of organ systems. DE can interfere with normal physiology after acute and chronic exposure to particulate matter (PM). Exposure leads to potential systemic disease processes in the central nervous, visual, hematopoietic, respiratory, cardiovascular, and renal systems. In this review, we give an overview of the epidemiological evidence supporting the harmful effects of diesel exhaust, and the numerous animal studies conducted to investigate the specific pathophysiological mechanisms behind DE exposure. Additionally, this review includes a summary of studies that used biomarkers as an indication of biological plausibility, and also studies evaluating new technology diesel exhaust (NTDE) and its systemic effects. Lastly, this review includes new approaches to improving DE emissions, and emphasizes the importance of ongoing study in this field of environmental health.

Benzene and childhood acute leukemia in Oklahoma

BACKGROUND

Although childhood cancer is a leading cause of childhood mortality in the US, evidence regarding the etiology is lacking. The goal of this study was to evaluate the association between benzene, a known carcinogen, and childhood acute leukemia.

METHODS

We conducted a case-control study including cases diagnosed with acute leukemia between 1997 and 2012 (n = 307) from the Oklahoma Central Cancer Registry and controls matched on week of birth from birth certificates (n = 1013). We used conditional logistic regression to evaluate the association between benzene, measured with the 2005 National-Scale Air Toxics Assessment (NATA) at census tract of the birth residence, and childhood acute leukemia.

RESULTS

We observed no differences in benzene exposure overall between cases and controls. However, when stratified by year of birth, cases born from 2005 to 2010 had a three-fold increased unadjusted odds of elevated exposure compared to controls born in this same time period (4th Quartile OR: 3.53, 95% CI: 1.35, 9.27). Furthermore, the estimates for children with acute myeloid leukemia (AML) were stronger than those with acute lymphoid leukemia, though not statistically significant.

CONCLUSIONS

While we did not observe an association between benzene and childhood leukemia overall, our results suggest that acute leukemia is associated with increased benzene exposure among more recent births, and children with AML may have increased benzene exposure at birth. Using the NATA estimates allowed us to assess a specific pollutant at the census tract level, providing an advantage over monitor or point source data. Our study, however, cannot rule out the possibility that benzene may be a marker of other traffic-related exposures and temporal misclassification may explain the lack of an association among earlier births.

Road Traffic Pollution and Childhood Leukemia: A Nationwide Case-control Study in Italy

BACKGROUND

The association of childhood leukemia with traffic pollution was considered in a number of studies from 1989 onwards, with results not entirely consistent and little information regarding subtypes.

AIM OF THE STUDY

We used the data of the Italian SETIL case-control on childhood leukemia to explore the risk by leukemia subtypes associated to exposure to vehicular traffic.

METHODS

We included in the analyses 648 cases of childhood leukemia (565 Acute lymphoblastic-ALL and 80 Acute non lymphoblastic-AnLL) and 980 controls. Information on traffic exposure was collected from questionnaire interviews and from the geocoding of house addresses, for all periods of life of the children.

RESULTS

We observed an increase in risk for AnLL, and at a lower extent for ALL, with indicators of exposure to traffic pollutants. In particular, the risk was associated to the report of closeness of the house to traffic lights and to the passage of trucks (OR: 1.76; 95% CI 1.03-3.01 for ALL and 6.35; 95% CI 2.59-15.6 for AnLL). The association was shown also in the analyses limited to AML and in the stratified analyses and in respect to the house in different period of life.

CONCLUSIONS

Results from the SETIL study provide some support to the association of traffic related exposure and risk for AnLL, but at a lesser extent for ALL. Our conclusion highlights the need for leukemia type specific analyses in future studies. Results support the need of controlling exposure from traffic pollution, even if knowledge is not complete.

Maternal exposure to ambient air pollution and risk of early childhood cancers: A population-based study in Ontario, Canada

BACKGROUND

There are increasing concerns regarding the role of exposure to ambient air pollution during pregnancy in the development of early childhood cancers.

OBJECTIVE

This population based study examined whether prenatal and early life (<1year of age) exposures to ambient air pollutants, including nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤2.5μm (PM_2.5), were associated with selected common early childhood cancers in Canada.

METHODS

2,350,898 singleton live births occurring between 1988 and 2012 were identified in the province of Ontario, Canada. We assigned temporally varying satellite-derived estimates of PM_2.5 and land-use regression model estimates of NO₂ to maternal residences during pregnancy. Incident cases of 13 subtypes of pediatric cancers among children up to age 6 until 2013 were ascertained through administrative health data linkages. Associations of trimester-specific, overall pregnancy and first year of life exposures were evaluated using Cox proportional hazards models, adjusting for potential confounders.

RESULTS

A total of 2044 childhood cancers were identified. Exposure to PM_2.5, per interquartile range increase, over the entire pregnancy, and during the first trimester was associated with an increased risk of astrocytoma (hazard ratio (HR) per 3.9μg/m3=1.38 (95% CI: 1.01, 1.88) and, HR per 4.0μg/m³=1.40 (95% CI: 1.05-1.86), respectively). We also found a positive association between first trimester NO₂ and acute lymphoblastic leukemia (ALL) (HR=1.20 (95% CI: 1.02-1.41) per IQR (13.3ppb)).

CONCLUSIONS

In this population-based study in the largest province of Canada, results suggest an association between exposure to ambient air pollution during pregnancy, especially in the first trimester and an increased risk of astrocytoma and ALL. Further studies are required to replicate the findings of this study with adjustment for important individual-level confounders.