Indoor PM2.5 in an urban zone with heavy wood smoke pollution: The case of Temuco, Chile

Temuco is a mid-size city representative of severe wood smoke pollution in southern Chile; however, little is known about the indoor air quality in this region. A field measurement campaign at 63 households in the Temuco urban area was conducted in winter 2014 and is reported here. In this study, indoor and outdoor (24-hr) PM_2.5 and its elemental composition were measured and compared. Infiltration parameters and outdoor/indoor contributions to indoor PM_2.5 were also determined. A statistical evaluation of how various air quality interventions and household features influence indoor PM_2.5 was also performed. This study determined median indoor and outdoor PM_2.5 concentrations of 44.4 and 41.8 μg/m³, respectively. An average infiltration factor (0.62 ± 0.06) was estimated using sulfur as a tracer species. Using a simple mass balance approach, median indoor and outdoor contributions to indoor PM_2.5 concentrations were then estimated as 12.5 and 26.5 μg/m³, respectively; therefore, 68% of indoor PM_2.5 comes from outdoor infiltration. This high percentage is due to high outdoor pollution and relatively high household air exchange rates (median: 1.06 h^-1). This study found that S, Br and Rb were dominated by outdoor contributions, while Si, Ca, Ti, Fe and As originated from indoor sources. Using continuous indoor and outdoor PM_2.5 measurements, a median indoor source strength of 75 μg PM_2.5/min was estimated for the diurnal period, similar to literature results. For the evening period, the median estimate rose to 135 μg PM_2.5/min, reflecting a more intense wood burning associated to cooking and space heating at night. Statistical test results (at the 90% confidence level) support the ongoing woodstove replacement program (reducing emissions) and household weatherization subsidies (reducing heating demand) for improving indoor air quality in southern Chile, and suggest that a cookstove improvement program might be helpful as well.

Effects of temperature and resource variation on insect population dynamics: the bordered plant bug as a case study

In species with complex life cycles, population dynamics result from a combination of intrinsic cycles arising from delays in the operation of negative density-dependent processes (e.g., intraspecific competition) and extrinsic fluctuations arising from seasonal variation in the abiotic environment. Abiotic variation can affect species directly through their life history traits and indirectly by modulating the species' interactions with resources or natural enemies.We investigate how the interplay between density-dependent dynamics and abiotic variability affects population dynamics of the bordered plant bug (Largus californicus), a Hemipteran herbivore inhabiting the California coastal sage scrub community. Field data show a striking pattern in abundance: adults are extremely abundant or nearly absent during certain periods of the year, leading us to predict that seasonal forcing plays a role in driving observed dynamics.We develop a stage-structured population model with variable developmental delays, in which fecundity is affected by both intra-specific competition and temporal variation in resource availability and all life history traits (reproduction, development, mortality) are temperature-dependent. We parameterize the model with experimental data on temperature-responses of life history and competitive traits and validate the model with independent field census data.We find that intra-specific competition is strongest at temperatures optimal for reproduction, which theory predicts leads to more complex population dynamics. Our model predicts that while temperature or resource variability interact with development-induced delays in self-limitation to generate population fluctuations, it is the interplay between all three factors that drive the observed dynamics. Considering how multiple abiotic factors interact with density-dependent processes is important both for understanding how species persist in variable environments and predicting species' responses to perturbations in their typical environment.

Short-term dynamics of indoor and outdoor endotoxin exposure: Case of Santiago, Chile, 2012

Indoor and outdoor endotoxin in PM2.5 was measured for the very first time in Santiago, Chile, in spring 2012. Average endotoxin concentrations were 0.099 and 0.094 [EU/m(3)] for indoor (N=44) and outdoor (N=41) samples, respectively; the indoor-outdoor correlation (log-transformed concentrations) was low: R=-0.06, 95% CI: (-0.35 to 0.24), likely owing to outdoor spatial variability. A linear regression model explained 68% of variability in outdoor endotoxins, using as predictors elemental carbon (a proxy of traffic emissions), chlorine (a tracer of marine air masses reaching the city) and relative humidity (a modulator of surface emissions of dust, vegetation and garbage debris). In this study, for the first time a potential source contribution function (PSCF) was applied to outdoor endotoxin measurements. Wind trajectory analysis identified upwind agricultural sources as contributors to the short-term, outdoor endotoxin variability. Our results confirm an association between combustion particles from traffic and outdoor endotoxin concentrations. For indoor endotoxins, a predictive model was developed but it only explained 44% of endotoxin variability; the significant predictors were tracers of indoor PM2.5 dust (Si, Ca), number of external windows and number of hours with internal doors open. Results suggest that short-term indoor endotoxin variability may be driven by household dust/garbage production and handling. This would explain the modest predictive performance of published models that use answers to household surveys as predictors. One feasible alternative is to increase the sampling period so that household features would arise as significant predictors of long-term airborne endotoxin levels.

Abstract P1-03-06: Population Based In Vivo Biomarker Discovery Using Engineered Human Tumors

Background:

Tumors from patients exhibit significant inter-tumor variation, where each tumor harbors a unique set of genetic alterations that impact prognosis and response to treatment. Unfortunately, this variation contributes to low response rates in the clinic and creates significant challenges for treating patients with appropriate drugs. Cancer cell line based xenografts have traditionally been the preclinical model of choice to assess the efficacy of clinical compounds; however, such in vitro models exhibit inherent artifacts, and are unable to adequately capture natural variation seen in human tumor populations. It has therefore become a priority in oncology and personalized medicine to match patients to drugs that will result in a favorable treatment outcome. In this report, we describe a population based approach for response prediction featuring naturally occurring variation in tumors derived from genetically defined human-in-mouse models of cancer. Materials and Methods:

A population of De novo human breast tumors were generated by genetically engineering normal primary human breast epithelial cells with HER2 and SV40 early region (HER2/SV40er) or KRAS and SV40 early region (KRAS/SV40er) in an in vivo Human-In-Mouse (HIM) tissue transgenic model (Wu et al, Proc Natl Acad Sci U S A 2009, 106: 7022-2027). Each tumor of the population has been comprehensively characterized histopathologically, and at the RNA and DNA level. Furthermore, the population has been adapted to conduct quantitative efficacy studies of anti-cancer agents and combinations. Results:

The HER2/SV40er and the KRAS/SV40er HIM tumors develop as invasive human breast adenocarcinoma that are histologically similar to those observed in patients. Microarray and CGH profiling demonstrated significant inter-tumor variation among the established tumors, as has been reported for patient tumors. Moreover, the KRAS/SV40er tumors clustered with basal type breast cancers from patients, a poor prognosis human breast cancer subtype. Both HER2/SV40er and KRAS/SV40er tumors exhibited variable responses to treatments with the potent selective triple VEGFR inhibitor, tivozanib. Further characterization of those tumors, both pre-and post-treatment, identified potential biomarkers for tumor response to tivozanib. Discussion:

The genetically defined human-in-mouse tumors exhibited natural variations similar to that occurs in human cancer. This population-based HIM system enables us to identify and validate biomarkers of therapeutic response in an in vivo human tumor model. Figure available in online version.

Randomized phase III study comparing paclitaxel/cisplatin/gemcitabine (PCG) and gemcitabine/cisplatin (GC) in patients with locally advanced (LA) or metastatic (M) urothelial cancer without prior systemic therapy; EORTC30987/Intergroup Study

LBA5030

Background: GC is a standard alternative to M-VAC for LA/M urothelial cancer (UC) based on comparable efficacy and a more favorable toxicity profile. Based on a phaseII trial, it has been suggested that the PCG triplet might provide improved response and survival. To evaluate the role of paclitaxel when added to GC, a randomized, international study (EORTC30987/Intergroup Study) comparing GC with PCG in LA/M UC was initiated in 2001, with the main endpoint being overall survival (OS). Methods: Chemo naive patients with histologic evidence of LA or M transitional UC, with GFR>60ml/min were eligible. After stratification for institution, PS(WHO 0–1) and presence/absence of metastatic disease, patients were randomized to receive PCG(armA) or GC(armB). PCG treatment included: paclitaxel(P) 80mg/m2 d1&8, cisplatin(C) 70mg/m2 d1 and gemcitabine(G) 1000mg/m2 d1&8, every 21d. GC: C70mg/m2 d1 or 2, G1000mg/m2 d1,8,15 every 28d. To detect an increase in median survival from 14 to 18m(HR=0.778) based on a two sided logrank test at error rates a=0.05 and β=0.20, 498 deaths were required. The planned sample size was of 610 pts. Results: From June 01 to May 04, 627pts (82% primary bladder) were included, (312 PCG, 315 GC). Median age was 61y with 81% males and similar baseline prognostic characteristics on both arms. PS 1 in 47%PCG and 46%GC pts. On PCG 47% had visceral and 83% M; on CG 49%-83% respectively. Overall response rate (RR): 57,1% for PCG (CR15%) and 46,4% for GC (CR10%), p=0.02. Median PFS: 8.4m and 7.7m for PCG and GC, p=0.10. 478 pts have died; the EORTC IDMC has released the study because the required number of events will occur prior to presentation. Median survival is 15.7m for PCG and 12.8m for CG, with no significant difference in OS (p=0.10, HR0.86, CI95% 0.72–1.03, p=0.12 adjusted for risk factors). Both treatments were overall well tolerated, with more thrombopenia and bleeding on GC (12%vs7%) and more febrile neutropenia on PCG (13%vs4%). Conclusions: This large, multicenter, Phase III study shows that PCG provided a better RR when compared with GC in LA/M UC; however the predefined endpoint for PFS and OS improvement was not reached.

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Functional characterization of transforming growth factor beta signaling in Smad2- and Smad3-deficient fibroblasts

A prominent pathway of transforming growth factor (TGF)-beta signaling involves receptor-dependent phosphorylation of Smad2 and Smad3, which then translocate to the nucleus to activate transcription of target genes. To investigate the relative importance of these two Smad proteins in TGF-beta1 signal transduction, we have utilized a loss of function approach, based on analysis of the effects of TGF-beta1 on fibroblasts derived from mouse embryos deficient in Smad2 (S2KO) or Smad3 (S3KO). TGF-beta1 caused 50% inhibition of cellular proliferation in wild-type fibroblasts as assessed by [(3)H]thymidine incorporation, whereas the growth of S2KO or S3KO cells was only weakly inhibited by TGF-beta1. Lack of Smad2 or Smad3 expression did not affect TGF-beta1-induced fibronectin synthesis but resulted in markedly suppressed induction of plasminogen activator inhibitor-1 by TGF-beta1. Moreover, TGF-beta1-mediated induction of matrix metalloproteinase-2 was selectively dependent on Smad2, whereas induction of c-fos, Smad7, and TGF-beta1 autoinduction relied on expression of Smad3. Investigation of transcriptional activation of TGF-beta-sensitive reporter genes in the different fibroblasts showed that activation of the (Smad binding element)(4)-Lux reporter by TGF-beta1 was dependent on expression of Smad3, but not Smad2, whereas activation of the activin response element-Lux reporter was strongly suppressed in S2KO fibroblasts but, on the contrary, enhanced in S3KO cells. Our findings indicate specific roles for Smad2 and Smad3 in TGF-beta1 signaling.

TBX1 is responsible for cardiovascular defects in velo-cardio-facial/DiGeorge syndrome

Velo-cardio-facial syndrome (VCFS)/DiGeorge syndrome (DGS) is a human disorder characterized by a number of phenotypic features including cardiovascular defects. Most VCFS/DGS patients are hemizygous for a 1.5-3.0 Mb region of 22q11. To investigate the etiology of this disorder, we used a cre-loxP strategy to generate mice that are hemizygous for a 1.5 Mb deletion corresponding to that on 22q11. These mice exhibit significant perinatal lethality and have conotruncal and parathyroid defects. The conotruncal defects can be partially rescued by a human BAC containing the TBX1 gene. Mice heterozygous for a null mutation in Tbx1 develop conotruncal defects. These results together with the expression patterns of Tbx1 suggest a major role for this gene in the molecular etiology of VCFS/DGS.

The DNA mismatch repair genes Msh3 and Msh6 cooperate in intestinal tumor suppression

Repair of mismatches in DNA in mammalian cells is mediated by a complex of proteins that are members of two highly conserved families of genes referred to as MutS and MutL homologues. Germline mutations in several members of these families, MSH2, MSH6, MLH1, and PMS2, but not MSH3, are responsible for hereditary non-polyposis colorectal cancer. To examine the role of MSH3, we generated a mouse with a null mutation in this gene. Cells from Msh3-/- mice are defective in repair of insertion/ deletion mismatches but can repair base-base mismatches. Msh3-/- mice develop tumors at a late age. When the Msh3-/- and Msh6-/- mutations are combined, the tumor predisposition phenotype is indistinguishable from Msh2-/- or Mlh1-/- mice. These results suggest that MSH3 cooperates with MSH6 in tumor suppression.

Postgastrulation Smad2-deficient embryos show defects in embryo turning and anterior morphogenesis

SMAD2 is a member of the transforming growth factor beta and activin-signaling pathway. To examine the role of Smad2 in postgastrulation development, we independently generated mice with a null mutation in this gene. Smad2-deficient embryos die around day 7.5 of gestation because of failure of gastrulation and failure to establish an anterior-posterior (A-P) axis. Expression of the homeobox gene Hex (the earliest known marker of the A-P polarity and the prospective head organizer) was found to be missing in Smad2-deficient embryos. Homozygous mutant embryos and embryonic stem cells formed mesoderm derivatives revealing that mesoderm induction is SMAD2 independent. In the presence of wild-type extraembryonic tissues, Smad2-deficient embryos developed beyond 7.5 and up to 10.5 days postcoitum, demonstrating a requirement for SMAD2 in extraembryonic tissues for the generation of an A-P axis and gastrulation. The rescued postgastrulation embryos showed malformation of head structures, abnormal embryo turning, and cyclopia. Our results show that Smad2 expression is required at several stages during embryogenesis.

Mouse models for colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers in the Western world. Much has been learned about colorectal cancer from human inherited syndromes, such as familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC). Mouse models for CRC were generated by introducing mutations into the mouse genes, whose human counterparts were implicated in the onset and progression of CRC. Central among these are mice carrying mutations in the Adenomatous polyposis coli (Apc) gene. Although most of these Apc mutations share some common phenotypes as homozygous embryonic lethality and tumor predisposition, the severity of the tumor predisposition is variable. Mice with mutations in the mismatch repair genes, Msh2 and Mlh1, exhibit a mismatch repair defect and are predisposed to developing gastrointestinal cancer, lymphomas and tumors of other organ systems. Mice carrying a mutation in the Pms2 gene are predisposed to lymphomas and other tumors. Mice with a mutation in the Msh6 gene have a defect in base mismatch repair and show a tumor predisposition phenotype. Mice with mutations in Mlh1, Pms2 and Msh5 have defects in meiosis suggesting unique roles for these genes in gametogenesis.

Tumorigenesis in Mlh1 and Mlh1/Apc1638N mutant mice

An3 1 KAL I MutL homologue 1 (MLH1) is a member of the family of proteins required for DNA mismatch repair. Germ-line mutations in MLH1 lead to the cancer susceptibility syndrome hereditary nonpolyposis colorectal cancer (HNPCC). We generated mice carrying a null mutation in the Mlh1 gene. We showed that mice heterozygous and homozygous for the Mlh1 gene are predisposed to developing tumors of the gastrointestinal (GI) tract, lymphomas, and a number of other tumor types. We also examined the role of adenomatous polyposis coli gene (Apc) gene mutations in the GI tumors of Mlh1 mutant mice by different methods and showed that the GI tumors in Mlh1 mice express little or no adenomatous polyposis coli protein. When an Apc gene mutation was bred into the Mlh1 mutant mice, the GI tumor incidence increased 40-100-fold. The wild-type Apc allele in these tumors was found to contain mutations. Together, these results show that we have developed two mouse models for human HNPCC and that the mechanisms of tumor development in the GI tract of these mice involve loss of Apc gene function in a manner very similar to that seen in the GI tumors of HNPCC.

Mammalian MutS homologue 5 is required for chromosome pairing in meiosis

MSH5 (MutS homologue 5) is a member of a family of proteins known to be involved in DNA mismatch repair. Germline mutations in MSH2, MLH1 and GTBP (also known as MSH6) cause hereditary non-polyposis colon cancer (HNPCC) or Lynch syndrome. Inactivation of Msh2, Mlh1, Gtmbp (also known as Msh6) or Pms2 in mice leads to hereditary predisposition to intestinal and other cancers. Early studies in yeast revealed a role for some of these proteins, including Msh5, in meiosis. Gene targeting studies in mice confirmed roles for Mlh1 and Pms2 in mammalian meiosis. To assess the role of Msh5 in mammals, we generated and characterized mice with a null mutation in Msh5. Msh5-/- mice are viable but sterile. Meiosis in these mice is affected due to the disruption of chromosome pairing in prophase I. We found that this meiotic failure leads to a diminution in testicular size and a complete loss of ovarian structures. Our results show that normal Msh5 function is essential for meiotic progression and, in females, gonadal maintenance.

Goosecoid-like (Gscl), a candidate gene for velocardiofacial syndrome, is not essential for normal mouse development

Velocardiofacial syndrome (VCFS) and DiGeorge syndrome (DGS) are characterized by a wide spectrum of abnormalities, including conotruncal heart defects, velopharyngeal insufficiency, craniofacial anomalies and learning disabilities. In addition, numerous other clinical features have been described, including frequent psychiatric illness. Hemizygosity for a 1.5-3 Mb region of chromosome 22q11 has been detected in >80% of VCFS/DGS patients. It is thought that a developmental field defect is responsible for many of the abnormalities seen in these patients and that the defect occurs due to reduced levels of a gene product active in early embryonic development. Goosecoid-like ( GSCL ) is a homeobox gene which is present in the VCFS/DGS commonly deleted region. The mouse homolog, Gscl, is expressed in mouse embryos as early as E8.5. Gscl is related to Goosecoid ( Gsc ), a gene required for proper craniofacial development in mice. GSCL has been considered an excellent candidate for contributing to the developmental defects in VCFS/DGS patients. To investigate the role of Goosecoid-like in VCFS/DGS etiology, we disrupted the Gscl gene in mouse embryonic stem cells and produced mice that transmit the disrupted allele. Mice that are homozygous for the disrupted allele appear to be normal and they do not exhibit any of the anatomical abnormalities seen in VCFS/DGS patients. RNA in situ hybridization to mouse embryo sections revealed that Gscl is expressed at E8.5 in the rostral region of the foregut and at E11.5 and E12.5 in the developing brain, in the pons region and in the choroid plexus of the fourth ventricle. Although the gene inactivation experiments indicate that haploinsufficiency for GSCL is unlikely to be the sole cause of the developmental field defect thought to be responsible for many of the abnormalities in VCFS/DGS patients, its localized expression during development could suggest that hemizygosity for GSCL, in combination with hemizygosity for other genes in 22q11, contributes to some of the developmental defects as well as the behavioral anomalies seen in these patients. The mice generated in this study should help in evaluating these possibilities.

The interleukin 2 receptor alpha chain/CD25 promoter is a target for nuclear factor of activated T cells

The expression of the murine interleukin (IL)-2 receptor alpha chain/CD25 is strongly induced at the transcriptional level after T cell activation. We show here that nuclear factor of activated T cell (NF-AT) factors are involved in the control of CD25 promoter induction in T cells. NF-ATp and NF-ATc bind to two sites around positions -585 and -650 located upstream of the proximal CD25 promoter. Immediately 3' from these NF-AT motifs, nonconsensus sites are located for the binding of AP-1-like factors. Mutations of sites that suppress NF-AT binding impair the induction and strong NF-ATp-mediated transactivation of the CD25 promoter in T cells. In T lymphocytes from NF-ATp-deficient mice, the expression of CD25 is severely impaired, leading to a delayed IL-2 receptor expression after T cell receptor (TCR)/CD3 stimulation. Our data indicate an important role for NF-AT in the faithful expression of high affinity IL-2 receptors and a close link between the TCR-mediated induction of IL-2 and IL-2 receptor alpha chain promoters, both of which are regulated by NF-AT factors.

Retarded thymic involution and massive germinal center formation in NF-ATp-deficient mice

NF-ATp and NF-ATc are the most prominent nuclear NF-AT transcription factors in peripheral T lymphocytes. After T cell activation both factors bind to and control the promoters and enhancers of numerous lymphokine and receptor ligand genes. In order to define a specific role for NF-ATp in vivo we have inactivated the NF-ATp gene by gene targeting in mice. We show that NF-ATp deficiency leads to the accumulation of peripheral T cells with a "preactivated" phenotype, enhanced immune responses of T cells after secondary stimulation in vitro and severe defects in the proper termination of antigen responses, as shown by a reduced deletion of superantigen-reactive CD4+ T cells. These alterations in the function of the immune system are correlated with drastic changes in the morphology of lymphoid organs. Approximately 25 % of NF-ATp-deficient mice older than 6 months develop large germinal centers in the spleen and peripheral lymph nodes. In addition, they exhibit a pronounced retardation in the involution of the thymus. The thymus of these NF-ATp-deficient mice exhibits large cortical areas typical for newborn mice and a massive infiltration of IgM+/ IgD+ B lymphocytes. Contrary to the T lymphocytes from IL-2-deficient mice which develop a phenotype similar to the NF-ATp-/- mice, NF-ATp-/- T cells do not show obvious defects in Fas-mediated apoptosis. This might indicate defects in other types of programmed cell death which are controlled by the activity of NF-ATp.

Inefficient termination of antigen responses in NF-ATp-deficient mice

In order to elucidate the role of NF-ATp, one of the most prominent members of family of NF-AT transcription factors in peripheral T lymphocytes, in T cell activation and differentiation we created NF-ATp-deficient mice by gene targeting. Such NF-ATp-/- mice are born and appear to develop a normal immune system. Apart from clear-cut defects in the synthesis of mRNAs for Th2-type lymphokines, such as IL-4, IL-5, IL-10 and IL-13, in primary and secondary stimulations of spleen cells in vitro, of a distinct impaired deletion of V beta 11+/CD4+ T lymphocytes from these mice was detected after superantigen injection. Moreover, NF-ATp-/- mice older than 6 weeks show an 2-5 fold increase in number of lymphocytes. This is correlated with an increased expression of activation markers CD44 and CD69 and decreased expression of CD62.

Mutation in the mismatch repair gene Msh6 causes cancer susceptibility

Mice carrying a null mutation in the mismatch repair gene Msh6 were generated by gene targeting. Cells that were homozygous for the mutation did not produce any detectable MSH6 protein, and extracts prepared from these cells were defective for repair of single nucleotide mismatches. Repair of 1, 2, and 4 nucleotide insertion/deletion mismatches was unaffected. Mice that were homozygous for the mutation had a reduced life span. The mice developed a spectrum of tumors, the most predominant of which were gastrointestinal tumors and B- as well as T-cell lymphomas. The tumors did not show any microsatellite instability. We conclude that MSH6 mutations, like those in some other members of the family of mismatch repair genes, lead to cancer susceptibility, and germline mutations in this gene may be associated with a cancer predisposition syndrome that does not show microsatellite instability.