Towards recycling of waste carbon fiber: Strength, morphology and structural features of recovered carbon fibers

Carbon fiber is one of the most widely used materials in high demand applications due to its high specific properties, however, its post-recycling properties limit its use to low performance applications. In this research, the carbon fiber recovering is examined using two methods: two-step pyrolysis and microwave-assisted thermolysis. The results indicate that the fibers recovered by pyrolysis show reduced surface and structural damage, maintaining the original mechanical properties of the fiber with losses below 5%. The fibers recovered by microwaves undergo significant surface changes that reduce their tensile strength by up to 60% and changes in their graphitic structure, increasing their degree of crystallinity by Raman index I_D/I_G from 1.98 to 2.86 and their amorphous degree by I_D"/I_G ratio from 0.411 to 1.599. Recovering fibers from microwave technique is 70% faster compared to two step pyrolysis, and provides recycled fibers with superior surface activation with the presence of polar functional groups -OH, -CO, and -CH that react with the epoxy matrix. The thermal, morphological, structural and mechanical characterizations of the recovered fibers detailed in this work provide valuable findings to evaluate their direct reuse in new composite materials.

RSL24D1 sustains steady-state ribosome biogenesis and pluripotency translational programs in embryonic stem cells

Embryonic stem cell (ESC) fate decisions are regulated by a complex circuitry that coordinates gene expression at multiple levels from chromatin to mRNA processing. Recently, ribosome biogenesis and translation have emerged as key pathways that efficiently control stem cell homeostasis, yet the underlying molecular mechanisms remain largely unknown. Here, we identified RSL24D1 as highly expressed in both mouse and human pluripotent stem cells. RSL24D1 is associated with nuclear pre-ribosomes and is required for the biogenesis of 60S subunits in mouse ESCs. Interestingly, RSL24D1 depletion significantly impairs global translation, particularly of key pluripotency factors and of components from the Polycomb Repressive Complex 2 (PRC2). While having a moderate impact on differentiation, RSL24D1 depletion significantly alters ESC self-renewal and lineage commitment choices. Altogether, these results demonstrate that RSL24D1-dependant ribosome biogenesis is both required to sustain the expression of pluripotent transcriptional programs and to silence PRC2-regulated developmental programs, which concertedly dictate ESC homeostasis.

Machine learning-based detection of label-free cancer stem-like cell fate

The detection of cancer stem-like cells (CSCs) is mainly based on molecular markers or functional tests giving a posteriori results. Therefore label-free and real-time detection of single CSCs remains a difficult challenge. The recent development of microfluidics has made it possible to perform high-throughput single cell imaging under controlled conditions and geometries. Such a throughput requires adapted image analysis pipelines while providing the necessary amount of data for the development of machine-learning algorithms. In this paper, we provide a data-driven study to assess the complexity of brightfield time-lapses to monitor the fate of isolated cancer stem-like cells in non-adherent conditions. We combined for the first time individual cell fate and cell state temporality analysis in a unique algorithm. We show that with our experimental system and on two different primary cell lines our optimized deep learning based algorithm outperforms classical computer vision and shallow learning-based algorithms in terms of accuracy while being faster than cutting-edge convolutional neural network (CNNs). With this study, we show that tailoring our deep learning-based algorithm to the image analysis problem yields better results than pre-trained models. As a result, such a rapid and accurate CNN is compatible with the rise of high-throughput data generation and opens the door to on-the-fly CSC fate analysis.

SMAD2/3 mediate oncogenic effects of TGF-β in the absence of SMAD4

TGF-β signaling is involved in pancreatic ductal adenocarcinoma (PDAC) tumorigenesis, representing one of the four major pathways genetically altered in 100% of PDAC cases. TGF-β exerts complex and pleiotropic effects in cancers, notably via the activation of SMAD pathways, predominantly SMAD2/3/4. Though SMAD2 and 3 are rarely mutated in cancers, SMAD4 is lost in about 50% of PDAC, and the role of SMAD2/3 in a SMAD4-null context remains understudied. We herein provide evidence of a SMAD2/3 oncogenic effect in response to TGF-β1 in SMAD4-null human PDAC cancer cells. We report that inactivation of SMAD2/3 in SMAD4-negative PDAC cells compromises TGF-β-driven collective migration mediated by FAK and Rho/Rac signaling. Moreover, RNA-sequencing analyses highlight a TGF-β gene signature related to aggressiveness mediated by SMAD2/3 in the absence of SMAD4. Using a PDAC patient cohort, we reveal that SMAD4-negative tumors with high levels of phospho-SMAD2 are more aggressive and have a poorer prognosis. Thus, loss of SMAD4 tumor suppressive activity in PDAC leads to an oncogenic gain-of-function of SMAD2/3, and to the onset of associated deleterious effects.

In pancreatic ductal adenocarcinoma cells and patient tissue, SMAD2/3 is shown to mediate oncogenic effects of TGF-β in the absence of SMAD4.

Effect of the donor´s age and type of extender (egg yolk versus clarified egg yolk) over the sperm quality of Majorera bucks preserved at 4 ºC: in vitro results and fertility trials

This study assessed the effect of donor´s age and two different extenders in the sperm quality of chilled semen in Majorera bucks. In experiment 1, semen was individually processed from 5 young (10–12 months old) and 4 mature (3–5 years old) bucks and then was diluted in two different extenders: EY (Tris‐glucose, 12% egg yolk) and CEY (Tris‐glucose, 12% clarified egg yolk) and cooled at 4°C; semen quality (sperm motility, percentages of alive spermatozoa, acrosome status and abnormal spermatozoa) was evaluated at 24, 48, 72 and 96 hr after cooling. In experiment II, 72 Majorera goats were assigned to four experimental groups: for groups 24‐EY (n = 18) and 24‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 24 hr, respectively, while for groups 72‐EY (n = 18) and 72‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 72 hr, respectively. In vitro results confirmed that only ejaculate volume and sperm concentration were significantly different between young and mature bucks. In addition, semen quality was similar between both diluents, presenting values for the first 48 hr similar to that recorded in fresh samples. The fertility rate was around 70% after 24 hr (4°C) in both groups, but the kidding rate was significantly lower (44.4%, p < .05) in goats inseminated with EY diluent preserved for 72 hr. Our results showed that the semen samples may be stored at 4°C in media with egg yolk or clarified egg yolk, and, therefore, the use of clarified egg yolk may represent a valid alternative to chill semen samples. Finally, young bucks (older than 10–12 months) of Majorera breed could be successfully used in breeding programmes with similar efficacy to older males.

Consensus statement: summary of the Quebec Lung Cancer Network recommendations for prioritizing patients with thoracic cancers in the context of the COVID-19 pandemic

Background

The emergence of covid-19 has the potential to change the way in which the health care system can accommodate various patient populations and might affect patients with non-covid-19 problems. The Quebec Lung Cancer Network, which oversees thoracic oncology services in the province of Quebec under the direction of the Ministère de la Santé et des Services sociaux, convened to develop recommendations to deal with the potential disruption of services in thoracic oncology in the province of Quebec. The summary provided here has been adapted from the original document posted on the Programme québécois du cancer Web site at: https://www.msss.gouv.qc.ca/professionnels/documents/coronavirus-2019-ncov/PJ1_Recommandations_oncologie-thoracique-200415.pdf.

Methods

Plans to optimize the health care system and potentially to prioritize services were discussed with respect to various levels of activity. For each level-of-activity scenario, suggestions were made for the services and treatments to prioritize and for those that might have to be postponed, as well as for potential alternatives to care.

Results

The principal recommendation is that the cancer centre executive committee and the multidisciplinary tumour board always try to find a solution to maintain standard-of-care therapy for all patients with thoracic tumours, using novel approaches to treatment and the adoption of a network approach to care, as needed.

Conclusions

The effect of the covid-19 pandemic on the health care system remains unpredictable and requires that cancer teams unite and offer the most efficient and innovative therapies to all patients under the various conditions that might be forced upon them.

Generation of an Fsp1 (fibroblast-specific protein 1)-Flpo transgenic mouse strain

Recombination systems represent a major breakthrough in the field of genetic model engineering. The Flp recombinases (Flp, Flpe, and Flpo) bind and cleave DNA Frt sites. We created a transgenic mouse strain ([Fsp1‐Flpo]) expressing the Flpo recombinase in fibroblasts. This strain was obtained by random insertion inside mouse zygotes after pronuclear injection. Flpo expression was placed under the control of the promoter of Fsp1 (fibroblast‐specific protein 1) gene, whose expression starts after gastrulation at Day 8.5 in cells of mesenchymal origin. We verified the correct expression and function of the Flpo enzyme by several ex vivo and in vivo approaches. The [Fsp1‐Flpo] strain represents a genuine tool to further target the recombination of transgenes with Frt sites specifically in cells of mesenchymal origin or with a fibroblastic phenotype.

Schwann cells support oncogenic potential of pancreatic cancer cells through TGFβ signaling

Pancreatic ductal adenocarcinoma (PDAC) is one of the solid tumors with the poorest prognosis. The stroma of this tumor is abundant and composed of extracellular matrix and stromal cells (including cancer-associated fibroblasts and immune cells). Nerve fibers invading this stroma represent a hallmark of PDAC, involved in neural remodeling, which participates in neuropathic pain, cancer cell dissemination and tumor relapse after surgery. Pancreatic cancer-associated neural remodeling is regulated through functional interplays mediated by physical and molecular interactions between cancer cells, nerve cells and surrounding Schwann cells, and other stromal cells. In the present study, we show that Schwann cells (glial cells supporting peripheral neurons) can enhance aggressiveness (migration, invasion, tumorigenicity) of pancreatic cancer cells in a transforming growth factor beta (TGFβ)-dependent manner. Indeed, we reveal that conditioned medium from Schwann cells contains high amounts of TGFβ able to activate the TGFβ-SMAD signaling pathway in cancer cells. We also observed in human PDAC samples that high levels of TGFβ signaling activation were positively correlated with perineural invasion. Secretome analyses by mass spectrometry of Schwann cells and pancreatic cancer cells cultured alone or in combination highlighted the central role of TGFβ in neuro-epithelial interactions, as illustrated by proteomic signatures related to cell adhesion and motility. Altogether, these results demonstrate that Schwann cells are a meaningful source of TGFβ in PDAC, which plays a crucial role in the acquisition of aggressive properties by pancreatic cancer cells.

Adherence to guidelines in requesting Oncotype DX in a publicly funded health care system

Background

Oncotype dx [odx (Genomic Health, Redwood City, CA, U.S.A.)] is an approved prognostic tool for women with node-negative, hormone receptor-positive, her2-negative breast cancer. Because of cost, optimal use of this test is crucial, especially in a publicly funded health care system. We evaluated adherence with our provincial guidelines for odx requests, the management of patients with an intermediate recurrence score (rs), and the cost impact of odx.

Methods

This retrospective study included 201 consecutive patients with an odx request from two university institutions in Quebec between May 2012 and December 2014. Concordance with provincial guidelines was estimated, with its 95% confidence interval (ci). For patients with an intermediate rs, factors influencing the final treatment decision were assessed. The cost impact of odx was derived from the proportion of patients for whom chemotherapy was not recommended.

Results

In 93.0% of patients (95% ci: 89.5% to 96.6%), odx was ordered according to guidelines. The concordance was similar in both institutions (92.7%; 95% ci: 88.1% to 97.3%; and 93.6%; 95% ci: 88.2% to 99.0%). In 112 (55.7%), 78 (38.8%), and 9 (4.5%) patients, the rs suggested low, intermediate, and high risk respectively. In the intermediate-risk group, most patients (n = 58, 74.4%) did not receive chemotherapy, mainly because of patient preference and the absence of a clear proven benefit. Savings of CA$100,000 for the study period (2.5 years) were estimated to be associated with odx use.

Conclusions

In our experience, the use of odx was concordant with published recommendations and had a positive cost impact.

Acinar-to-Ductal Metaplasia Induced by Transforming Growth Factor Beta Facilitates KRASG12D-driven Pancreatic Tumorigenesis

BACKGROUND & AIMS

Transforming growth factor beta (TGFβ) acts either as a tumor suppressor or as an oncogene, depending on the cellular context and time of activation. TGFβ activates the canonical SMAD pathway through its interaction with the serine/threonine kinase type I and II heterotetrameric receptors. Previous studies investigating TGFβ-mediated signaling in the pancreas relied either on loss-of-function approaches or on ligand overexpression, and its effects on acinar cells have so far remained elusive.

METHODS

We developed a transgenic mouse model allowing tamoxifen-inducible and Cre-mediated conditional activation of a constitutively active type I TGFβ receptor (TβRICA) in the pancreatic acinar compartment.

RESULTS

We observed that TβRICA expression induced acinar-to-ductal metaplasia (ADM) reprogramming, eventually facilitating the onset of KRASG12D-induced pre-cancerous pancreatic intraepithelial neoplasia. This phenotype was characterized by the cellular activation of apoptosis and dedifferentiation, two hallmarks of ADM, whereas at the molecular level, we evidenced a modulation in the expression of transcription factors such as Hnf1β, Sox9, and Hes1.

CONCLUSIONS

We demonstrate that TGFβ pathway activation plays a crucial role in pancreatic tumor initiation through its capacity to induce ADM, providing a favorable environment for KRASG12D-dependent carcinogenesis. Such findings are highly relevant for the development of early detection markers and of potentially novel treatments for pancreatic cancer patients.

The economic consequences of obesity and overweight among adults in Quebec

OBJECTIVES

This article presents the first study of the economic consequences of obesity and overweight in the Canadian province of Quebec. The article examines three types of direct costs: hospitalizations, medical visits and drug consumption; and one type of indirect cost: productivity loss due to disability.

METHODS

The National Population Health Survey, conducted in all Canadian provinces by Statistics Canada between 1994 and 2011, provides self-reported longitudinal data for body mass index and the frequency of health care utilization and disability.

RESULTS

When we compared obese adults in Quebec to those with a normal weight at the beginning of the follow-up period, we observed that the former had significantly more frequent visits to the physician, more frequent hospital stays and higher consumption of drugs between 1994 and 2011. We estimated the annual cost of the excess health care utilization and excess disability at more than CAD $2.9 billion in 2011.

CONCLUSION

The results confirm that, similar to what had been found elsewhere in Canada and abroad, there are important economic consequences associated with overweight and obesity in Quebec.

Abstract P2-05-30: OncotypeDX® for breast cancer: A multigene assay that makes a difference?

Objective: OncotypeDX® (ODX) is a multigene diagnostic assay that can estimate the 10 year-risk of distant recurrence in women with hormone receptor positive (HR+) and node negative (N–) early breast cancer. The testreports a Recurrence Score® (RS) and three risk group categories have been described: low-risk (&lt;18), intermediate-risk (18-30) and high-risk (≥31). It helps the oncologist in the adjuvant chemotherapy decision process and globally leads to a reduction in the recommendation for chemotherapy use. This test is expensive and represents an economic burden in a publicly funded province. Nonetheless, its use has been approved over other gene expression profiling like Mammaprint® based on the evidence of its prognostic and predictive ability. We evaluated the adequacy of the requests for the ODX in an academic setting after the introduction in May 2012 of a reference framework for its use in Québec, Canada and the impact on chemotherapy recommendation. The costs generated by the test were also determined. Methods: We included all patients with an ODX request from two University Centers, CICM and CHUS, and estimated the concordance with the current provincial guideline for which an ODX may be ordered (invasive breast cancer HR+/Her2–/N- that is T1b with unfavorable characteristics or T1c or T2). For the intermediate-risk group, the factors influencing the final decision to use systemic chemotherapy were analysed. The projected cost-effectiveness of the ODX was derived from the proportion of patients (pts) for which the chemotherapy was not recommended. Results: Between May 2012 and December 2014, a total of 201 pts, 123 pts from CICM and 78 from CHUS, had an ODX done. In 93,0% (95%CI, 89,5-96,6) of pts, ODX was ordered correctly with respect to the guideline. There was no statistical differences between both sites (CICM: 92,7% [95%CI, 97,3-88,1]; CHUS 93,6% [95%CI, 88,2-99,0]). A total of 9 pts had high-risk RS (4,5%), 78 pts had intermediate-risk RS (38,8%) and 112 pts had low-risk RS (55,7%). Chemotherapy was recommended for 31 pts (18,2%) instead of an estimated 58,0% prior to the use of ODX according to previous reports published. In the intermediate-risk group, the majority of pts (74,4%) did not receive chemotherapy. The patient's preference and the absence of a proven benefit were the main reasons for withholding chemotherapy in this group. The additional cost associated with the use of the ODX was compensated with the reduction of the adjuvant systemic chemotherapy prescribed and its derived expenses (chemotherapy cost, nursing time and hospitalisations) and savings of 100 K were observed. Conclusions: In early breast cancer HR+ and N-, the use of ODX in two University Hospitals is concordant with published recommendations. ODX use is cost effective. This benefice does not take into account the psychological burden that comes with the decision to use adjuvant chemotherapy; neither does it evaluate potential long term complications. The widespread use of ODX must be looked at critically in face of other emerging gene signature tests like Endopredict® and PAM50®. As for the predictive ability of the ODX for adjuvant chemotherapy, one can question the strength of the actual evidence and argue if it confers this test an advantage over other multigene assays.

Citation Format: Martel S, Prady C, Simon R, Matte C. OncotypeDX® for breast cancer: A multigene assay that makes a difference? [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-30.

TIF1γ Suppresses Tumor Progression by Regulating Mitotic Checkpoints and Chromosomal Stability

The transcription accessory factor TIF1γ/TRIM33/RFG7/PTC7/Ectodermin functions as a tumor suppressor that promotes development and cellular differentiation. However, its precise function in cancer has been elusive. In the present study, we report that TIF1γ inactivation causes cells to accumulate chromosomal defects, a hallmark of cancer, due to attenuations in the spindle assembly checkpoint and the post-mitotic checkpoint. TIF1γ deficiency also caused a loss of contact growth inhibition and increased anchorage-independent growth in vitro and in vivo. Clinically, reduced TIF1γ expression in human tumors correlated with an increased rate of genomic rearrangements. Overall, our work indicates that TIF1γ exerts its tumor-suppressive functions in part by promoting chromosomal stability.

Projection scenarios of body mass index (2013-2030) for Public Health Planning in Quebec

Background

Projection analyses can provide estimates of the future health burden of increasing BMI and represent a relevant and useful tool for public health planning. Our study presents long-term (2013–2030) projections of the prevalence and numbers of individuals by BMI category for adult men and women in Quebec. Three applications of projections to estimate outcomes more directly pertinent to public health planning, as well as an in-depth discussion of limits, are provided with the aim of encouraging greater use of projection analyses by public health officers.

Methods

The weighted compositional regression method is applied to prevalence time series derived from sixteen cross-sectional survey cycles, for scenarios of linear change and deceleration. Estimation of the component of projected change potentially amenable to intervention, future health targets and the projected impact on type 2 diabetes, were done.

Results

Obesity prevalence in Quebec is projected to rise steadily from 2013 to 2030 in both men (from 18.0-19.4% to 22.2-30.4%) and women (from 15.5-16.3% to 18.2-22.4%). Corresponding projected numbers of obese individuals are (579,000-625,000 to 790,000-1,084,000) in men and (514,000-543,000 to 661,000-816,000) in women. These projected increases are found to be primarily an ‘epidemiologic’ rather than ‘demographic’ phenomenon and thus potentially amenable to public health intervention. Assessment of obesity targets for 2020 illustrates the necessity of using projected rather than current prevalence; for example a targeted 2% drop in obesity prevalence relative to 2013 translates into a 3.6-5.4% drop relative to 2020 projected levels. Type 2 diabetes is projected to increase from 6.9% to 9.2-10.1% in men and from 5.7% to 7.1-7.5% in women, from 2011–2012 to 2030. A substantial proportion of this change (25-44% for men, and 27-43% for women) is attributable to the changing BMI distribution.

Conclusions

Obesity in Quebec is projected to increase and should therefore continue to be a public health priority. Application of projections to estimate the proportion of change potentially amenable to intervention, feasible health targets, and future chronic disease prevalence are demonstrated. Projection analyses have limitations, but represent a pertinent tool for public health planning.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-996) contains supplementary material, which is available to authorized users.

Tenascin-X promotes epithelial-to-mesenchymal transition by activating latent TGF-β

Transforming growth factor β (TGF-β) isoforms are secreted as inactive complexes formed through noncovalent interactions between the bioactive TGF-β entity and its N-terminal latency-associated peptide prodomain. Extracellular activation of the latent TGF-β complex is a crucial step in the regulation of TGF-β function for tissue homeostasis. We show that the fibrinogen-like (FBG) domain of the matrix glycoprotein tenascin-X (TNX) interacts physically with the small latent TGF-β complex in vitro and in vivo, thus regulating the bioavailability of mature TGF-β to cells by activating the latent cytokine into an active molecule. Activation by the FBG domain most likely occurs through a conformational change in the latent complex and involves a novel cell adhesion-dependent mechanism. We identify α11β1 integrin as a cell surface receptor for TNX and show that this integrin is crucial to elicit FBG-mediated activation of latent TGF-β and subsequent epithelial-to-mesenchymal transition in mammary epithelial cells.

Mortality inequality in populations with equal life expectancy: Arriaga's decomposition method in SAS, Stata, and Excel

PURPOSE

Life expectancy is used to measure population health, but large differences in mortality can be masked even when there is no life expectancy gap. We demonstrate how Arriaga's decomposition method can be used to assess inequality in mortality between populations with near equal life expectancy.

METHODS

We calculated life expectancy at birth for Quebec and the rest of Canada from 2005 to 2009 using life tables and partitioned the gap between both populations into age and cause-specific components using Arriaga's method.

RESULTS

The life expectancy gap between Quebec and Canada was negligible (<0.1 years). Decomposition of the gap showed that higher lung cancer mortality in Quebec was offset by cardiovascular mortality in the rest of Canada, resulting in identical life expectancy in both groups. Lung cancer in Quebec had a greater impact at early ages, whereas cardiovascular mortality in Canada had a greater impact at older ages.

CONCLUSIONS

Despite the absence of a gap, we demonstrate using decomposition analyses how lung cancer at early ages lowered life expectancy in Quebec, whereas cardiovascular causes at older ages lowered life expectancy in Canada. We provide SAS/Stata code and an Excel spreadsheeet to facilitate application of Arriaga's method to other settings.

Comparing life expectancy and health-adjusted life expectancy by body mass index category in adult Canadians: a descriptive study

BACKGROUND

While many studies have examined differences between body mass index (BMI) categories in terms of mortality risk and health-related quality of life (HRQL), little is known about the effect of body weight on health expectancy. We examined life expectancy (LE), health-adjusted life expectancy (HALE), and proportion of LE spent in nonoptimal (or poor) health by BMI category for the Canadian adult population (age ≥ 20).

METHODS

Respondents to the National Population Health Survey (NPHS) were followed for mortality outcomes from 1994 to 2009. Our study population at baseline (n=12,478) was 20 to 100 years old with an average age of 47. LE was produced by building abridged life tables by sex and BMI category using data from the NPHS and the Canadian Chronic Disease Surveillance System. HALE was estimated using the Health Utilities Index from the Canadian Community Health Survey as a measure of HRQL. The contribution of HRQL to loss of healthy life years for each BMI category was also assessed using two methods: by calculating differences between LE and HALE proportional to LE and by using a decomposition technique to separate out mortality and HRQL contributions to loss of HALE.

RESULTS

At age 20, for both sexes, LE is significantly lower in the underweight and obesity class 2+ categories, but significantly higher in the overweight category when compared to normal weight (obesity class 1 was nonsignificant). HALE at age 20 follows these same associations and is significantly lower for class 1 obesity in women. Proportion of life spent in nonoptimal health and decomposition of HALE demonstrate progressively higher losses of healthy life associated with lowered HRQL for BMI categories in excess of normal weight.

CONCLUSIONS

Although being in the overweight category for adults may be associated with a gain in life expectancy as compared to normal weight adults, overweight individuals also experience a higher proportion of these years of life in poorer health. Due to the descriptive nature of this study, further research is needed to explore the causal mechanisms which explain these results, including the important differences we observed between sexes and within obesity subcategories.

Isolation and culture of mouse primary pancreatic acinar cells

This protocol permits rapid isolation (in less than 1 hr) of murine pancreatic acini, making it possible to maintain them in culture for more than one week. More than 20 x 10(6) acinar cells can be obtained from a single murine pancreas. This protocol offers the possibility to independently process as many as 10 pancreases in parallel. Because it preserves acinar architecture, this model is well suited for studying the physiology of the exocrine pancreas in vitro in contrast to cell lines established from pancreatic tumors, which display many genetic alterations resulting in partial or total loss of their acinar differentiation.

Tif1γ suppresses murine pancreatic tumoral transformation by a Smad4-independent pathway

Transcriptional intermediary factor 1γ (TIF1γ; alias, TRIM33/RFG7/PTC7/ectodermin) belongs to an evolutionarily conserved family of nuclear factors that have been implicated in stem cell pluripotency, embryonic development, and tumor suppression. TIF1γ expression is markedly down-regulated in human pancreatic tumors, and Pdx1-driven Tif1γ inactivation cooperates with the Kras(G12D) oncogene in the mouse pancreas to induce intraductal papillary mucinous neoplasms. In this study, we report that aged Pdx1-Cre; LSL-Kras(G12D); Tif1γ(lox/lox) mice develop pancreatic ductal adenocarcinomas (PDACs), an aggressive and always fatal neoplasm, demonstrating a Tif1γ tumor-suppressive function in the development of pancreatic carcinogenesis. Deletion of SMAD4/DPC4 (deleted in pancreatic carcinoma locus 4) occurs in approximately 50% of human cases of PDAC. We, therefore, assessed the genetic relationship between Tif1γ and Smad4 signaling in pancreatic tumors and found that Pdx1-Cre; LSL-Kras(G12D); Smad4(lox/lox); Tif1γ(lox/lox) (alias, KSSTT) mutant mice exhibit accelerated tumor progression. Consequently, Tif1γ tumor-suppressor effects during progression from a premalignant to a malignant state in our mouse model of pancreatic cancer are independent of Smad4. These findings establish, for the first time to our knowledge, that Tif1γ and Smad4 both regulate an intraductal papillary mucinous neoplasm-to-PDAC sequence through distinct tumor-suppressor programs.

Accurate positioning of magnetic microparticles beyond the spatial resolution of clinical MRI scanners using susceptibility artifacts

Susceptibility-based negative contrast in magnetic resonance imaging (MRI) provides a mean to visualize magnetic microparticles. In the presence of a number of microparticles in the field of view (FOV), the shape of the artifact is affected by the dipole-dipole interaction between the particles. Due to the limited spatial resolution of the clinical MR scanners, the exact positioning of the particles in MR images is not possible. However, the shape of the artifact can shed light on how the particles are distributed within the FOV. In this work, a simulation model and in-vitro experiments were used to study the shape and the amount of the susceptibility artifact for various spacing and angulations between the microparticles. The results showed that for a pair of identical particles with a diameter of D, the signal loss starts to change when particles are separated ~15 × D and they become fully distinguishable when their distance reaches ~ 40 × D.

Safety evaluation of magnetic catheter steering with upgraded magnetic resonance imaging system

Catheter navigation and placement through the arterial network is a major limitation for clinical procedure. In this article, a specific catheter tip and a modified clinical MRI scanner with an upgraded gradient system are used to steer a catheter through a single Y-shaped bifurcation. Safety aspects are analyzed to avoid the peripheral nerve stimulation (PNS) according to an empirical law of magnetostimulation and the magnetic field of upgraded 3D gradient coils. For a rabbit-sized device, the rising time of gradients system have to be limited to 1.7ms at 400mT.m(-1) to avoid PNS. These rise time values allow the use of this system for catheter steering and other more demanding applications.

MRI visualization of a single 15 µm navigable imaging agent and future microrobot

In magnetic resonance imaging (MRI), the susceptibility-based contrast provides a way to amplify the effects of a magnetic microparticle, whereas its volume is largely inferior to the spatial resolution of the system. This concept presents an approach to visualization by means of susceptibility artifact using ferromagnetic microparticles. In this work, the amount of the susceptibility artifact was investigated using a simulation model and in vitro experiments on stainless steel microspheres measuring 40, 20 and 15 microm in diameter. The results showed that using a clinical MRI system, a single 15 microm microsphere is detectable in gradient-echo scans. The extent of the susceptibility artifact was found to be related to the scan parameters and the particles' sizes. Since the same ferromagnetic microparticle can be used for MRI-based propulsion, these results suggest several potential applications for navigable agents and microrobots involved in therapy, diagnostics, and imaging inside the microvascular network of the human body.

Inactivation of TIF1gamma cooperates with Kras to induce cystic tumors of the pancreas

Inactivation of the Transforming Growth Factor Beta (TGFbeta) tumor suppressor pathway contributes to the progression of Pancreatic Ductal AdenoCarcinoma (PDAC) since it is inactivated in virtually all cases of this malignancy. Genetic lesions inactivating this pathway contribute to pancreatic tumor progression in mouse models. Transcriptional Intermediary Factor 1 gamma (TIF1gamma) has recently been proposed to be involved in TGFbeta signaling, functioning as either a positive or negative regulator of the pathway. Here, we addressed the role of TIF1gamma in pancreatic carcinogenesis. Using conditional Tif1gamma knockout mice (Tif1gamma(lox/lox)), we selectively abrogated Tif1gamma expression in the pancreas of Pdx1-Cre;Tif1gamma(lox/lox) mice. We also generated Pdx1-Cre;LSL-Kras(G12D);Tif1gamma(lox/lox) mice to address the effect of Tif1gamma loss-of-function in precancerous lesions induced by oncogenic Kras(G12D). Finally, we analyzed TIF1gamma expression in human pancreatic tumors. In our mouse model, we showed that Tif1gamma was dispensable for normal pancreatic development but cooperated with Kras activation to induce pancreatic tumors reminiscent of human Intraductal Papillary Mucinous Neoplasms (IPMNs). Interestingly, these cystic lesions resemble those observed in Pdx1-Cre;LSL-Kras(G12D);Smad4(lox/lox) mice described by others. However, distinctive characteristics, such as the systematic presence of endocrine pseudo-islets within the papillary projections, suggest that SMAD4 and TIF1gamma don't have strictly redundant functions. Finally, we report that TIF1gamma expression is markedly down-regulated in human pancreatic tumors by quantitative RT-PCR and immunohistochemistry supporting the relevance of these findings to human malignancy. This study suggests that TIF1gamma is critical for tumor suppression in the pancreas, brings new insight into the genetics of pancreatic cancer, and constitutes a promising model to decipher the respective roles of SMAD4 and TIF1gamma in the multifaceted functions of TGFbeta in carcinogenesis and development.

Inactivation of TIF1gamma cooperates with Kras to induce cystic tumors of the pancreas

Inactivation of the Transforming Growth Factor Beta (TGFβ) tumor suppressor pathway contributes to the progression of Pancreatic Ductal AdenoCarcinoma (PDAC) since it is inactivated in virtually all cases of this malignancy. Genetic lesions inactivating this pathway contribute to pancreatic tumor progression in mouse models. Transcriptional Intermediary Factor 1 gamma (TIF1γ) has recently been proposed to be involved in TGFβ signaling, functioning as either a positive or negative regulator of the pathway. Here, we addressed the role of TIF1γ in pancreatic carcinogenesis. Using conditional Tif1γ knockout mice (Tif1γ^lox/lox), we selectively abrogated Tif1γ expression in the pancreas of Pdx1-Cre;Tif1γ^lox/lox mice. We also generated Pdx1-Cre;LSL-Kras^G12D;Tif1γ^lox/lox mice to address the effect of Tif1γ loss-of-function in precancerous lesions induced by oncogenic Kras^G12D. Finally, we analyzed TIF1γ expression in human pancreatic tumors. In our mouse model, we showed that Tif1γ was dispensable for normal pancreatic development but cooperated with Kras activation to induce pancreatic tumors reminiscent of human Intraductal Papillary Mucinous Neoplasms (IPMNs). Interestingly, these cystic lesions resemble those observed in Pdx1-Cre;LSL-Kras^G12D;Smad4^lox/lox mice described by others. However, distinctive characteristics, such as the systematic presence of endocrine pseudo-islets within the papillary projections, suggest that SMAD4 and TIF1γ don't have strictly redundant functions. Finally, we report that TIF1γ expression is markedly down-regulated in human pancreatic tumors by quantitative RT–PCR and immunohistochemistry supporting the relevance of these findings to human malignancy. This study suggests that TIF1γ is critical for tumor suppression in the pancreas, brings new insight into the genetics of pancreatic cancer, and constitutes a promising model to decipher the respective roles of SMAD4 and TIF1γ in the multifaceted functions of TGFβ in carcinogenesis and development.

Inactivation of the TGFβ tumor suppressor pathway contributes to the progression of Pancreatic Ductal AdenoCarcinoma (PDAC), a devastating malignancy. Transcriptional Intermediary Factor 1γ (TIF1γ) has recently been proposed to be involved in TGFβ signaling, a pathway inactivated in virtually all cases of this malignancy. To address the role of TIF1γ in pancreatic carcinogenesis, we used conditional Tif1γ knockout mice. In a genetic background expressing a constitutively active mutation of KRAS oncogene (Kras^G12D) recurrently found in patients with PDAC, Tif1γ inactivation induces pancreatic precancerous lesions resembling those observed in the absence of Smad4, a key player involved TGFβ signal transduction. This observation strengthens the notion that TIF1γ plays an active role in TGFβ signaling. Interestingly, we also found that TIF1γ expression was markedly down-regulated in human pancreatic tumors supporting the relevance of our findings to human malignancy. Characterization of new players involved in the outbreak of early pancreatic lesions that will eventually evolve into invasive pancreatic cancer is crucial to detect the disease earlier and eventually develop new therapeutic drugs.

iNKT cell development is orchestrated by different branches of TGF-beta signaling

Invariant natural killer T (iNKT) cells constitute a distinct subset of T lymphocytes exhibiting important immune-regulatory functions. Although various steps of their differentiation have been well characterized, the factors controlling their development remain poorly documented. Here, we show that TGF-beta controls the differentiation program of iNKT cells. We demonstrate that TGF-beta signaling carefully and specifically orchestrates several steps of iNKT cell development. In vivo, this multifaceted role of TGF-beta involves the concerted action of different pathways of TGF-beta signaling. Whereas the Tif-1gamma branch controls lineage expansion, the Smad4 branch maintains the maturation stage that is initially repressed by a Tif-1gamma/Smad4-independent branch. Thus, these three different branches of TGF-beta signaling function in concert as complementary effectors, allowing TGF-beta to fine tune the iNKT cell differentiation program.

Generation of mice with conditionally activated transforming growth factor beta signaling through the TbetaRI/ALK5 receptor

We generated a transgenic mouse strain (LSL-TbetaRI(CA)) containing a latent constitutively active TGFbeta type I receptor (TbetaRI/ALK5) by using a knock-in strategy into the X chromosome-linked hypoxanthine phosphoribosyl-transferase (Hprt) locus. Transgene expression, under the control of the ubiquitous CAG (human cytomegalovirus enhancer and chicken beta-actin) promoter, is repressed by a floxed transcriptional "Stop" (LSL, Lox-Stop-Lox). In the presence of cre-recombinase, the "Stop" is excised to allow TbetaRI(CA) transgene expression. We showed that restricted expression of TbetaRI(CA) in T lymphocytes efficiently activates TGFbeta signaling and rescues the T-cell autoimmune disorders of TGFbetaRII conditional knockouts. Unexpectedly, our study reveals that TGFbeta signaling upregulation controls T-cell activation but does not impair their development or their peripheral homeostasis. In addition to the information provided on TGFbeta effects on T-cell biology, LSL-TbetaRI(CA) mouse constitutes an attractive tool to address the effect of TGFbeta signaling upregulation in any cell type expressing the cre-recombinase.

Real-time software platform design for in-vivo navigation of a small ferromagnetic device in a swine carotid artery using a magnetic resonance imaging system

Using an 1.5T Siemens clinical Magnetic Resonance Imaging system (MRI), a 1.5 mm diameter ferromagnetic bead is moved across a pre-planned path in the carotid artery of a 25 kg living swine. The software architecture for the navigation and path planning is herein described. Using the real-time feedback capabilities of recent MRIs, the device is moved, controlled and tracked using the magnetic gradients coils already present for imaging purposes. Navigation of the ferromagnetic device has been achieved with a peak velocity of about 13 cm/s through a set of pre established 11 waypoints. The dedicated software architecture presented in this paper lies in a modified real-time MRI imaging sequence. The dedicated architecture permits the navigation of the ferromagnetic bead with an operating frequency of 24 Hz Real-time control of the magnetic core is achieved through the implementation of a simple 2D PID controller incorporated in the presented software platform.

Sequence design and software environment for real-time navigation of a wireless ferromagnetic device using MRI system and single echo 3D tracking

Software architecture for the navigation of a ferromagnetic untethered device in a 1D and 2D phantom environment is briefly described. Navigation is achieved using the real-time capabilities of a Siemens 1.5 T Avanto MRI system coupled with a dedicated software environment and a specially developed 3D tracking pulse sequence. Real-time control of the magnetic core is executed through the implementation of a simple PID controller. 1D and 2D experimental results are presented.

AF10-dependent transcription is enhanced by its interaction with FLRG

BACKGROUND INFORMATION

FLRG (follistatin-related gene) is a secreted glycoprotein which is very similar to follistatin. As observed for follistatin, FLRG is involved in the regulation of various biological processes through its binding to members of the TGFbeta (transforming growth factor beta) superfamily, activin, BMPs (bone morphogenetic proteins) and myostatin. Unlike follistatin, FLRG has been found to be both secreted and localized within the nucleus of many FLRG-producing cells, suggesting the existence of specific intracellular functions of the protein.

RESULTS

In order to analyse the function of the nuclear form of FLRG, we performed a yeast two-hybrid screen, in which we identified AF10 [ALL1 (acute lymphoblastic leukaemia) fused gene from chromosome 10], a translocation partner of the MLL (mixed-lineage leukaemia) oncogene in human leukaemia, as a FLRG-interacting protein. This interaction was confirmed by far-Western-blot analysis and co-immunoprecipitation with transfected COS-7 cells. The N-terminal region of AF10, including the PHD (plant homeodomain), is sufficient to mediate this interaction, and has been shown to be involved in AF10 homo-oligomerization. By immunoprecipitation experiments, we showed that FLRG enhances the homo-oligomerization of AF10. Functional studies demonstrated that FLRG enhances the transactivation properties of the AF10 protein fused to Gal4 DNA-binding domains in transient transfection assays.

CONCLUSIONS

Our present study provides novel insights into the function of the nuclear form of the FLRG protein, which is revealed as a novel regulator of transcription. The nuclear isoform of FLRG lacks an intrinsic transactivation domain, but enhances AF10-mediated transcription, probably through promoting the homo-oligomerization of AF10, thus facilitating the recruitment of co-activators.

In vivo MR-tracking based on magnetic signature selective excitation

A novel magnetic resonance (MR)-tracking method specifically developed to locate the ferromagnetic core of an untethered microdevice, microrobot, or nanorobot for navigation or closed-loop control purpose is described. The tracking method relies on the application of radio-frequency (RF) excitation signals tuned to the equipotential magnetic curves generated by the magnetic signature of the object being tracked. Positive contrast projections are obtained with reference to the position of the magnetic source. A correlation function performed on only one k-space line for each of the three axes and corresponding to three projections, is necessary to obtain a 3-D location of the device. In this study, the effects of the sphere size and the RF frequency offset were investigated in order to find the best contrast noise ratio (CNR) for tracking. Resolution and precision were also investigated by proper measurement of the position of a ferromagnetic sphere by magnetic resonance imaging (MRI) acquisition and by comparing them with the real position. This method is also tested for a moving marker where the positions found by MRI projections were compared with the ones taken with a camera. In vitro and in vivo experiments show the operation of the technique in tortuous phantom and in animal models. Although the method was developed in the prospect of new interventional MR-guided endovascular operations based on miniature untethered devices, it could also be used as a passive tracking method using tools such as catheters or guide wires.

Adapting MRI systems to propel and guide microdevices in the human blood circulatory system

Magnetic resonance imaging (MRI) systems are widely used to gather noninvasively images of the interior of the human body. This paper suggests that an MRI system can be seen beyond being just a tool for imaging purpose but one that can propel and guide special microdevices in the human body to perform specific medical tasks. More specifically, an MRI system can potentially be used to image the region of interest, propel a microdevice through the generation of magnetic gradients, determine the location of the device, compute the corrective actions through feedback control algorithms and adjust the generation of the magnetic gradients accordingly to navigate such a microdevice in a preplanned path. This paper presents an introductory description of the proposed techniques, the main issues to consider, and some preliminary data indicating the validity of this approach.

Identification of NF-kappaB responsive elements in follistatin related gene (FLRG) promoter

Follistatin related gene (FLRG) has been previously identified from a chromosomal translocation observed in a B-cell chronic lymphocytic leukemia (B-CLL). FLRG (alternative names: follistatin-related protein, FSRP/follistatin-like-3, FSTL3) is a secreted glycoprotein highly similar to follistatin. Like follistatin, FLRG is involved in the regulation of various biological effects through its binding to members of the transforming growth factor beta (TGFbeta) superfamily such as activin A and myostatin. We have previously shown that TGFbeta and activin A are potent inducers of FLRG transcriptional activation through the Smad proteins. Using a biochemical approach, we investigated whether tumor necrosis factor alpha (TNFalpha) could regulate FLRG expression since TNFalpha plays a critical role in hematopoietic malignancies. We demonstrate that TNFalpha activates FLRG expression at the transcriptional level. This activation depends on a promoter region containing four 107-108 bp DNA repeats, which are evolutionary conserved in primates. These repeats carry a strong phylogenetic signal, which is not common among non-coding sequences. Each DNA repeat contains one TNFalpha responsive element (5'-GGGAGAG/TTCC-3') able to bind nuclear factor kappaB (NF-kappaB) transcription factors. We also show that TGFbeta, through the Smad proteins, potentates the effect of TNFalpha on FLRG expression. This cooperation is unexpected since TGFbeta and TNFalpha usually have opposite biological effects. In all, this work brings new insights in the understanding of FLRG regulation by cytokines and growth factors. It opens attractive perspectives of research that should allow us to better understand the role of FLRG during tumorigenesis.

Real-time Magnetic Resonance Gradient-based Propulsion of a Wireless Microdevice Using Pre-Acquired Roadmap and Dedicated Software Architecture

A new method for the propulsion of a spherical ferromagnetic device along a given path in a water filled phantom with no human interaction is presented using an 1.5 T Magnetic Resonance Imaging (MRI) clinical system. A special real time loop is implemented and presented that feeds the scanner with the appropriate gradients amplitudes and directions based on a pre-determined path. This paper studies the necessary propulsion conditions and limitations such as device dimensions and necessary gradient amplitude as well as overall latency problems such as communication delays and computation delays needed to achieve precise propulsion. It also presents a dedicated software environment for path control and validation, propulsion and tracking of such device.

Potential Applications of Untethered Microdevices in the Blood Vessels within the Constraints of an MRI System

This paper presents potential medical applications that an untethered microdevice in the cardiovascular system could perform within an MRI system. Recent developments and continuing evolution in micro/nano fabrication and design techniques will enable the development of functional microdevices able to explore the cardiovascular system. The Magnetic Resonance Submarine (MR-Sub) project is a first step towards this goal. Magnetic force generated by the gradient coils of an MRI system provides a propulsion mechanism that simplifies miniaturization and bypasses energetic challenges. Untethered microdevices may play an important complementary role in the next generation of minimally invasive tools. A better efficiency and targetability of the treatments will be achieved when microsystems such as the MR-Sub will allow a more extensive access to smaller blood vessels.

Microdevice's susceptibility difference based MRI positioning system, a preliminary investigation

A positioning technique for an endovascular microdevice propelled by magnetic force inside a magnetic resonance imaging (MRI) system is being developed. Positioning options are presented and a magnetic positioning technique is described in more details. Since a magnetic positioning system is deeply dependent on the quality of the measurement modality, we describe the main magnetic field measurement techniques that can be used inside an MRI. Finally, we propose a magnetic positioning system using MRI phase images to measure the magnetic distortion induced by the ferromagnetic body. Positioning results on a 1010/1020 carbon steel, 1.5875 mm diameter sphere with gradient echo phase images are presented.

A novel role for fibronectin type I domain in the regulation of human hematopoietic cell adhesiveness through binding to follistatin domains of FLRG and follistatin

FLRG and follistatin belong to the family of follistatin proteins involved in the regulation of various biological effects, such as hematopoiesis, mediated by their binding to activin and BMP, both members of the TGFbeta family. To further characterize the function of FLRG, we searched for other possible functional partners using a yeast two-hybrid screen. We identified human fibronectin as a new partner for both FLRG and follistatin. We also demonstrated that their physical interaction is mediated by type I motifs of fibronectin and follistatin domains. We then analyzed the biological consequences of these protein interactions on the regulation of hematopoiesis. For the first time, we associated a biological effect with the regulation of human hematopoietic cell adhesiveness of both the type I motifs of fibronectin and the follistatin domains of FLRG and follistatin. Indeed, we observed a significant and specific dose-dependent increase of cell adhesion to fibronectin in the presence of FLRG or follistatin, using either a human hematopoietic cell line or primary cells. In particular, we observed a significantly increased adhesion of immature hematopoietic precursors (CFC, LTC-IC). Altogether these results highlight a new mechanism by which FLRG and follistatin regulate human hematopoiesis.

Diagnostic et classification des hypertensions artérielles pulmonaires

The clinical classification of types of pulmonary hypertension has made it possible to better standardize the approach to the diagnosis and treatment of patients, to perform clinical studies among homogeneous patients, and to discover common laboratory abnormalities that may serve as markers or help elucidate mechanisms of disease. Pulmonary arterial hypertension groups together different diseases that affect the small-caliber pulmonary arteries and lead to a progressive increase in pulmonary arterial resistance and right heart failure. A specific diagnosis of pulmonary arterial hypertension is generally based on a detailed and methodical clinical evaluation. Pulmonary biopsy is rarely indicated. Work-up in a center specialized in the management of this disease is frequently appropriate when the cause of the hypertension is not clear or when a specific treatment is envisaged.