EGFR amplification and EGFRvIII predict and participate in TAT-Cx43266-283 antitumor response in preclinical glioblastoma models

BACKGROUND

Glioblastoma (GBM) commonly displays epidermal growth factor receptor (EGFR) alterations (mainly amplification and EGFRvIII) and TAT-Cx43266-283 is a Src-inhibitory peptide with antitumor properties in preclinical GBM models. Given the link between EGFR and Src, the aim of this study was to explore the role of EGFR in the antitumor effects of TAT-Cx43266-283.

METHODS

The effect of TAT-Cx43266-283, temozolomide (TMZ) and erlotinib (EGFR inhibitor) was studied in patient-derived GBM stem cells (GSCs) and murine neural stem cells (NSCs) with and without EGFR alterations, in vitro and in vivo. EGFR alterations were analyzed by Western blot (WB) and Fluorescence In Situ Hybridization (FISH) in these cells, and compared with Src activity and survival in GBM samples from TCGA.

RESULTS

The effect of TAT-Cx43266-283 correlated with EGFR alterations in a set of patient-derived GSCs and was stronger than that exerted by TMZ and erlotinib. In fact, TAT-Cx43266-283 only affected NSCs with EGFR alterations, but not healthy NSCs. EGFR alterations correlated with Src activity and poor survival in GBM patients. Finally, tumors generated from NSCs with EGFR alterations, showed a decrease in growth, invasiveness and vascularization after treatment with TAT-Cx43266-283, which enhanced the survival of immunocompetent mice.

CONCLUSION

Clinically relevant EGFR alterations are predictors of TAT-Cx43266-283 response and part of its mechanism of action, even in TMZ- and erlotinib-resistant GSCs. TAT-Cx43266-283 targets NSCs with GBM-driver mutations, including EGFR alterations, in an immunocompetent GBM model in vivo, suggesting a promising effect on GBM recurrence. Together, this study represents an important step towards the clinical application of TAT-Cx43266-283.

Combination of BMI1 and MAPK/ERK inhibitors is effective in medulloblastoma

BACKGROUND

Epigenetic changes play a key role in the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor.

METHODS

We explore the therapeutic potential of BMI1 and MAPK/ERK inhibition in BMI1High;CHD7Low MB cells and in a preclinical xenograft model.

RESULTS

We identify a synergistic vulnerability of BMI1High;CHD7Low MB cells to a combination treatment with BMI1 and MAPK/ERK inhibitors. Mechanistically, CHD7-dependent binding of BMI1 to MAPK-regulated genes underpins the CHD7-BMI1-MAPK regulatory axis responsible of the antitumour effect of the inhibitors in vitro and in a preclinical mouse model. Increased ERK1 and ERK2 phosphorylation activity is found in BMI1High;CHD7Low G4 MB patients, raising the possibility that they could be amenable to a similar therapy.

CONCLUSIONS

The molecular dissection of the CHD7-BMI1-MAPK regulatory axis in BMI1High;CHD7Low MB identifies this signature as a proxy to predict MAPK functional activation, which can be effectively drugged in preclinical models, and paves the way for further exploration of combined BMI1 and MAPK targeting in G4 MB patients.

On-chip perivascular niche supporting stemness of patient-derived glioma cells in a serum-free, flowable culture

Glioblastoma multiforme (GBM) is the most common and the most aggressive type of primary brain malignancy. Glioblastoma stem-like cells (GSCs) can migrate in vascular niches within or away from the tumour mass, increasing tumour resistance to treatments and contributing to relapses. To study individual GSC migration and their interactions with the perivasculature of the tumour microenvironment, there is a need to develop a human organotypic in vitro model. Herein, we demonstrated a perivascular niche-on-a-chip, in a serum-free condition with gravity-driven flow, that supported the stemness of patient-derived GSCs and foetal neural stem cells grown in a three-dimensional environment (3D). Endothelial cells from three organ origins, (i) human brain microvascular endothelial cells (hCMEC/D3), (ii) human umbilical vein endothelial cells (HUVECs) and, (iii) human lung microvascular endothelial cells (HMVEC-L) formed rounded microvessels within the extracellular-matrix integrated microfluidic chip. By optimising cell extraction protocols, systematic studies were performed to evaluate the effects of serum-free media, 3D cell cultures, and the application of gravity-driven flow on the characteristics of endothelial cells and their co-culture with GSCs. Our results showed the maintenance of adherent and tight junction markers of hCMEC/D3 in the serum-free culture and that gravity-driven flow was essential to support adequate viability of both the microvessel and the GSCs in co-culture (>80% viability at day 3). Endpoint biological assays showed upregulation of neovascularization-related genes (e.g., angiopoietins, vascular endothelial growth factor receptors) in endothelial cells co-cultured with GSCs in contrast to the neural stem cell reference that showed insignificant changes. The on-chip platform further permitted live-cell imaging of GSC - microvessel interaction, enabling quantitative analysis of GSC polarization and migration. Overall, our comparative genotypic (i.e. qPCR) and phenotypic (i.e. vessel permeability and GSC migration) studies showed that organotypic (brain cancer cells-brain endothelial microvessel) interactions differed from those within non-tissue specific vascular niches of human origin. The development and optimization of this on-chip perivascular niche, in a serum-free flowable culture, could provide the next level of complexity of an in vitro system to study the influence of glioma stem cells on brain endothelium.

EMBR-10. INOSITOL TREATMENT INHIBITS MEDULLOBLASTOMA THROUGH SUPPRESSION OF EPIGENETIC-DRIVEN METABOLIC ADAPTATION

Medulloblastoma (MB) is the most common paediatric malignant brain tumour and is classified into four distinct molecular subgroups (WNT, SHH, G3 and G4), each of them further subdivided into subtypes with different prognosis and responses to therapy. Deregulation of chromatin modifier genes plays an essential role in MB, particularly in the G4 subgroup, the least understood of all subgroups, despite being the most common and associated with poor prognosis. A BMI1High; CHD7Low molecular signature identifies patients with poor survival within this subgroup. We show that BMI1High; CHD7Low mediates a novel epigenetic regulation of inositol metabolism in both G4 MB cells and patients. These tumours display hyperactivation of the AKT/mTOR pathway which leads to energetic rewiring characterized by enhanced glycolytic capacity and reduced mitochondrial function. We demonstrate that inositol administration counteracts this metabolic alteration, impairs MB proliferation in vitro and significantly extends survival in an in vivo pre-clinical model. Moreover, inositol synergises with cisplatin, a chemotherapy agent currently used in MB treatment, enhancing its therapeutic effect in vivo. Importantly, cerebellar neural stem cells bearing the BMI1High; CHD7Low signature do not show metabolic adaptation and are thus resistant to inositol treatment, highlighting a fundamental difference between normal and neoplastic metabolism in the developing cerebellum. In summary, we have identified an actionable vulnerability in a pre-clinical setting modelling a molecularly defined group of MB patients, the translational value of which can now be explored in signature-matched clinical trials in MB.

Glioblastomas acquire myeloid-affiliated transcriptional programs via epigenetic immunoediting to elicit immune evasion

Glioblastoma multiforme (GBM) is an aggressive brain tumor for which current immunotherapy approaches have been unsuccessful. Here, we explore the mechanisms underlying immune evasion in GBM. By serially transplanting GBM stem cells (GSCs) into immunocompetent hosts, we uncover an acquired capability of GSCs to escape immune clearance by establishing an enhanced immunosuppressive tumor microenvironment. Mechanistically, this is not elicited via genetic selection of tumor subclones, but through an epigenetic immunoediting process wherein stable transcriptional and epigenetic changes in GSCs are enforced following immune attack. These changes launch a myeloid-affiliated transcriptional program, which leads to increased recruitment of tumor-associated macrophages. Furthermore, we identify similar epigenetic and transcriptional signatures in human mesenchymal subtype GSCs. We conclude that epigenetic immunoediting may drive an acquired immune evasion program in the most aggressive mesenchymal GBM subtype by reshaping the tumor immune microenvironment.

The white matter is a pro-differentiative niche for glioblastoma

Glioblastomas are hierarchically organised tumours driven by glioma stem cells that retain partial differentiation potential. Glioma stem cells are maintained in specialised microenvironments, but whether, or how, they undergo lineage progression outside of these niches remains unclear. Here we identify the white matter as a differentiative niche for glioblastomas with oligodendrocyte lineage competency. Tumour cells in contact with white matter acquire pre-oligodendrocyte fate, resulting in decreased proliferation and invasion. Differentiation is a response to white matter injury, which is caused by tumour infiltration itself in a tumoursuppressive feedback loop. Mechanistically, tumour cell differentiation is driven by selective white matter upregulation of SOX10, a master regulator of normal oligodendrogenesis. SOX10 overexpression or treatment with myelination-promoting agents that upregulate endogenous SOX10, mimic this response, leading to niche-independent pre-oligodendrocyte differentiation and tumour suppression in vivo. Thus, glioblastoma recapitulates an injury response and exploiting this latent programme may offer treatment opportunities for a subset of patients.

Inositol treatment inhibits medulloblastoma through suppression of epigenetic-driven metabolic adaptation

Deregulation of chromatin modifiers plays an essential role in the pathogenesis of medulloblastoma, the most common paediatric malignant brain tumour. Here, we identify a BMI1-dependent sensitivity to deregulation of inositol metabolism in a proportion of medulloblastoma. We demonstrate mTOR pathway activation and metabolic adaptation specifically in medulloblastoma of the molecular subgroup G4 characterised by a BMI1High;CHD7Low signature and show this can be counteracted by IP6 treatment. Finally, we demonstrate that IP6 synergises with cisplatin to enhance its cytotoxicity in vitro and extends survival in a pre-clinical BMI1High;CHD7Low xenograft model.

Abstract 3777: The role of IFITMs in maintaining glioma stem cells

Glioblastoma (GBM), one of the most lethal and heterogeneous primary brain tumors, contains cellular hierarchies with both quiescent and self-renewing highly tumorigenic glioblastoma stem cells (GSCs). Cancer stem cells within the context of the brain likely contribute to a lack of progress in patient survival time as they appear to have an innate resistance to both chemotherapeutic drugs and radiotherapy. The aim of this study is to elucidate how constitutive expression of interferons (IFNs) and their downstream signalling pathways maintain GSCs thereby supporting treatment resistance and tumor reoccurrence. To understand the mechanism of action of a subset of IFN regulated genes, originally characterized as a signature for radiation and chemotherapy resistance (IRDS), a panel of patient derived glioma stem cells was generated and manipulated using CRISPR/Cas9 mediated gene-editing. Phenotypic changes in growth, viability and drug resistance were characterised in the edited cells and linked to molecular level events using transcriptomic and proteomic techniques. Using this approach, in conjunction with patient tissue analysis, signalling under basal as well as IFN-activated conditions was studied in the context of GSC status.

Immunohistopathology of a glioma tissue micro-array identified an increased expression of IFN induced transmembrane receptors (IFITMs), which co-localised with Nestin, around the blood vessels suggesting that IFITM positive cells were in the stem cell niche. Further analysis showed the presence of both IFITM1 and IFITM3 in GSCs and established that loss of IFITM function impacted on growth rate and cell cycle progression as well as treatment sensitivity. By using wild-type and gene-edited GSC to focus on the relationship between IFITM1 and IFITM3, we have compelling phenotypic and molecular evidence that IFN-induced changes in the localisation of IFITMs impact on the ability of stem cells to ‘escape' normal growth control mechanisms. Taking into consideration the constitutive expression of interferons in the tumor microenvironment, our study provides evidence that IFITMs regulate glioma stem cell self-renewal and are involved in maintaining a quiescent population which can escape chemotherapy.

Citation Format: Erisa Nita, Bernard Evers, Marta Nekulova, Gillian Morrison, Kathryn Ball. The role of IFITMs in maintaining glioma stem cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3777.

An efficient and scalable pipeline for epitope tagging in mammalian stem cells using Cas9 ribonucleoprotein

CRISPR/Cas9 can be used for precise genetic knock-in of epitope tags into endogenous genes, simplifying experimental analysis of protein function. However, Cas9-assisted epitope tagging in primary mammalian cell cultures is often inefficient and reliant on plasmid-based selection strategies. Here, we demonstrate improved knock-in efficiencies of diverse tags (V5, 3XFLAG, Myc, HA) using co-delivery of Cas9 protein pre-complexed with two-part synthetic modified RNAs (annealed crRNA:tracrRNA) and single-stranded oligodeoxynucleotide (ssODN) repair templates. Knock-in efficiencies of ~5-30%, were achieved without selection in embryonic stem (ES) cells, neural stem (NS) cells, and brain-tumor-derived stem cells. Biallelic-tagged clonal lines were readily derived and used to define Olig2 chromatin-bound interacting partners. Using our novel web-based design tool, we established a 96-well format pipeline that enabled V5-tagging of 60 different transcription factors. This efficient, selection-free and scalable epitope tagging pipeline enables systematic surveys of protein expression levels, subcellular localization, and interactors across diverse mammalian stem cells.

Dermal uptake of nicotine from air and clothing: Experimental verification

This study aims to elucidate in greater detail the dermal uptake of nicotine from air or from nicotine-exposed clothes, which was demonstrated recently in a preliminary study. Six non-smoking participants were exposed to gaseous nicotine (between 236 and 304 μg/m³ ) over 5 hours while breathing clean air through a hood. Four of the participants wore only shorts and 2 wore a set of clean clothes. One week later, 2 of the bare-skinned participants were again exposed in the chamber, but they showered immediately after exposure instead of the following morning. The 2 participants who wore clean clothes on week 1 were now exposed wearing a set of clothes that had been exposed to nicotine. All urine was collected for 84 hours after exposure and analyzed for nicotine and its metabolites, cotinine and 3OH-cotinine. All participants except those wearing fresh clothes excreted substantial amounts of biomarkers, comparable to levels expected from inhalation intake. Uptake for 1 participant wearing exposed clothes exceeded estimated intake via inhalation by >50%. Biomarker excretion continued during the entire urine collection period, indicating that nicotine accumulates in the skin and is released over several days. Absorbed nicotine was significantly lower after showering in 1 subject but not the other. Differences in the normalized uptakes and in the excretion patterns were observed among the participants. The observed cotinine half-lives suggest that non-smokers exposed to airborne nicotine may receive a substantial fraction through the dermal pathway. Washing skin and clothes exposed to nicotine may meaningfully decrease exposure.

Advanced buffer materials for indoor air CO2 control in commercial buildings

In this study, we evaluated solid sorbents for their ability to passively control indoor CO₂ concentration in buildings or rooms with cyclic occupancy (eg, offices, bedrooms). Silica supported amines were identified as suitable candidates and systematically evaluated in the removal of CO₂ from indoor air by equilibrium and dynamic techniques. In particular, sorbents with various amine loadings were synthesized using tetraethylenepentamine (TEPA), poly(ethyleneimine) (PEI) and a silane coupling agent 3-aminopropyltriethoxysilane (APS). TGA analysis indicates that TEPA impregnated silica not only displays a relatively high adsorption capacity when exposed to ppm level CO₂ concentrations, but also is capable of desorbing the majority of CO₂ by air flow (eg, by concentration gradient). In 10 L flow-through chamber experiments, TEPA-based sorbents reduced outlet CO₂ by up to 5% at 50% RH and up to 93% of CO₂ adsorbed over 8 hours was desorbed within 16 hours. In 8 m³ flow-through chamber experiments, 18 g of the sorbent powder spread over a 2 m² area removed approximately 8% of CO₂ injected. By extrapolating these results to real buildings, we estimate that meaningful reductions in the CO₂ can be achieved, which may help reduce energy requirements for ventilation and/or improve air quality.

Measurements of dermal uptake of nicotine directly from air and clothing

In this preliminary study, we have investigated whether dermal uptake of nicotine directly from air or indirectly from clothing can be a meaningful exposure pathway. Two participants wearing only shorts and a third participant wearing clean cotton clothes were exposed to environmental tobacco smoke (ETS), generated by mechanically "smoking" cigarettes, for three hours in a chamber while breathing clean air from head-enveloping hoods. The average nicotine concentration (420 μg/m³ ) was comparable to the highest levels reported for smoking sections of pubs. Urine samples were collected immediately before exposure and 60 hour post-exposure for bare-skinned participants. For the clothed participant, post-exposure urine samples were collected for 24 hour. This participant then entered the chamber for another three-hour exposure wearing a hood and clothes, including a shirt that had been exposed for five days to elevated nicotine levels. The urine samples were analyzed for nicotine and two metabolites-cotinine and 3OH-cotinine. Peak urinary cotinine and 3OH-cotinine concentrations for the bare-skinned participants were comparable to levels measured among non-smokers in hospitality environments before smoking bans. The amount of dermally absorbed nicotine for each bare-skinned participant was conservatively estimated at 570 μg, but may have been larger. For the participant wearing clean clothes, uptake was ~20 μg, and while wearing a shirt previously exposed to nicotine, uptake was ~80 μg. This study demonstrates meaningful dermal uptake of nicotine directly from air or from nicotine-exposed clothes. The findings are especially relevant for children in homes with smoking or vaping.

Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children

OBJECTIVES

In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures.

METHODS

Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm-based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed.

RESULTS

Average sensitivity and specificity (95 % confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70 % (58-82 %) and 97 % (94-100 %) respectively for DXA and 74 % (55-93 %) and 96 % (95-98 %) for radiographs. Fleiss' kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9 μSv for DXA and 232.7 μSv for radiographs. Image quality was similar.

CONCLUSION

Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children.

KEY POINTS

• Vertebral fracture diagnostic accuracy of lateral spine DXA is non-inferior to radiographs. • The rate of unreadable vertebrae for DXA is lower than for radiographs. • Effective dose of DXA is significantly lower than radiographs. • Children prefer DXA to radiographs. • Given the above, DXA should replace radiographs for paediatric vertebral fracture assessment.

Alignment and component position after patient-matched instrumentation versus conventional total knee arthroplasty

PURPOSE

To compare patient-matched instrumentation (PMI) with conventional total knee arthroplasty (TKA) in terms of limb alignment and component position.

METHODS

Nine men and 36 women (mean age, 69.5 years) who underwent PMI TKA were compared with 20 men and 25 women (mean age, 69.3 years) who underwent conventional TKA by the same team of surgeons with the same prosthesis and protocols in terms of limb alignment and component position using the Perth protocol computed tomography, as well as bone resection measurements, operating time, and the number of trays used.

RESULTS

The PMI and conventional TKA groups were comparable in terms of age, body mass index, tourniquet time, operating time, and the number of trays used. For limb alignment and component position, the 2 groups differed significantly in sagittal femoral component position (2.4º vs. 0.9º, p=0.0008) and the percentage of knees with femoral component internally rotated ≥1° with respect to the transepicondylar axis (20% vs. 55%, p=0.001). The difference was not significant in terms of limb alignment, coronal and rotational femoral component position, or coronal and sagittal tibial component position. Intra-operatively, all patient-matched cutting blocks demonstrated acceptable fit and stability. No instrument-related adverse events or complications were encountered. One (2.2%) femur and 6 (13.3%) tibiae were recut 2 mm for optimal ligament balancing. Two femoral components were upsized to the next size, and 2 tibial components were upsized and 2 downsized to the next size.

CONCLUSION

PMI was as accurate as conventional instrumentation in TKA. There was no significant difference in limb alignment or femoral and tibial component position in the coronal and sagittal planes between PMI and conventional TKA. PMI had a higher tendency to achieve correct femoral component rotation.

Methamphetamine absorption by skin lipids: accumulated mass, partition coefficients, and the influence of fatty acids

Occupants of former methamphetamine laboratories, often residences, may experience increased exposure through the accumulation of the methamphetamine in the organic films that coat skin and indoor surfaces. The objectives of this study were to determine equilibrium partition coefficients of vapor-phase methamphetamine with artificial sebum (AS-1), artificial sebum without fatty acids (AS-2), and real skin surface films, herein called skin oils. Sebum and skin oil-coated filters were exposed to vapor-phase methamphetamine at concentrations ranging from 8 to 159 ppb, and samples were analyzed for exposure time periods from 2 h to 60 days. For a low vapor-phase methamphetamine concentration range of ~8-22 ppb, the equilibrium partition coefficient for AS-1 was 1500 ± 195 μg/g/ppb. For a high concentration range of 98-112 ppb, the partition coefficient was lower, 459 ± 80 μg/g/ppb, suggesting saturation of the available absorption capacity. The low partition coefficient for AS-2 (33 ± 6 μg/g/ppb) suggests that the fatty acids in AS-1 and skin oil are responsible for much high partition coefficients. We predict that the methamphetamine concentration in skin lipids coating indoor surfaces can exceed recommended surface remediation standards even for air concentrations well below 1 ppb.

Benefit-cost analysis of commercially available activated carbon filters for indoor ozone removal in single-family homes

This study involved the development of a model for evaluating the potential costs and benefits of ozone control by activated carbon filtration in single-family homes. The modeling effort included the prediction of indoor ozone with and without activated carbon filtration in the HVAC system. As one application, the model was used to predict benefit-to-cost ratios for single-family homes in 12 American cities in five different climate zones. Health benefits were evaluated using disability-adjusted life-years and included city-specific age demographics for each simulation. Costs of commercially available activated carbon filters included capital cost differences when compared to conventional HVAC filters of similar particle removal efficiency, energy penalties due to additional pressure drop, and regional utility rates. The average indoor ozone removal effectiveness ranged from 4 to 20% across the 12 target cities and was largely limited by HVAC system operation time. For the parameters selected in this study, the mean predicted benefit-to-cost ratios for 1-inch filters were >1.0 in 10 of the 12 cities. The benefits of residential activated carbon filters were greatest in cities with high seasonal ozone and HVAC usage, suggesting the importance of targeting such conditions for activated carbon filter applications.

Dietary energy requirements in relatively healthy maintenance hemodialysis patients estimated from long-term metabolic studies

BACKGROUND

Studies that examined dietary energy requirements (DERs) of patients undergoing maintenance hemodialysis (MHD) have shown mixed results. Many studies reported normal DERs, but some described increased energy needs. DERs in MHD patients have been estimated primarily from indirect calorimetry and from nitrogen balance studies. The present study measured DERs in MHD patients on the basis of their dietary energy intake and changes in body composition.

OBJECTIVE

This study assessed DERs in MHD patients who received a constant energy intake while changes in their body composition were measured.

DESIGN

Seven male and 6 female sedentary, clinically stable MHD patients received a constant mean (±SD) energy intake for 92.2 ± 7.9 d while residing in a metabolic research ward. Changes in fat and fat-free mass, measured by dual-energy X-ray absorptiometry, were converted to calorie equivalents and added to energy intake to calculate energy requirements.

RESULTS

The average DER was 31 ± 3 kcal · kg(-1) · d(-1) calculated from energy intake and change in fat and fat-free calories, which was 28 ± 197 kcal/d over the 92 d of the study. DERs of MHD patients correlated strongly with their body weight (r = 0.81, P = 0.002) and less closely with their measured resting energy expenditure expressed as kcal/d (r = 0.69, P = 0.01). Although the average observed DER in MHD patients was similar to published estimated values for normal sedentary individuals of similar age and sex, there was wide variability in DER among individual patients (range: 26-36 kcal · kg(-1) · d(-1)).

CONCLUSIONS

Average DERs of sedentary, clinically stable patients receiving MHD are similar to those of sedentary normal individuals. Our data do not support the theory that MHD patients have increased DERs. Due to the high variability in DERs, careful monitoring of the nutritional status of individual MHD patients is essential. This trial was registered at clinicaltrials.gov as NCT02194114.

Convergence of cMyc and β-catenin on Tcf7l1 enables endoderm specification

The molecular machinery that directs formation of definitive endoderm from pluripotent stem cells is not well understood. Wnt/β-catenin and Nodal signalling have been implicated, but the requirements for lineage specification remain incompletely defined. Here, we demonstrate a potent effect of inhibiting glycogen synthase kinase 3 (GSK3) on definitive endoderm production. We find that downstream of GSK3 inhibition, elevated cMyc and β-catenin act in parallel to reduce transcription and DNA binding, respectively, of the transcriptional repressor Tcf7l1. Tcf7l1 represses FoxA2, a pioneer factor for endoderm specification. Deletion of Tcf7l1 is sufficient to allow upregulation of FoxA2 in the presence of Activin. In wild-type cells, cMyc contributes by reducing Tcf7l1 mRNA, while β-catenin acts on Tcf7l1 protein. GSK3 inhibition is further required for consolidation of endodermal fate via upregulation of Sox17, highlighting sequential roles for Wnt signalling. The identification of a cMyc/β-catenin-Tcf7l1-FoxA2 axis reveals a de-repression mechanism underlying endoderm induction that may be recapitulated in other developmental and patho-logical contexts.

UK service level audit of insulin pump therapy in paediatrics

AIM

To conduct an audit of insulin pump therapy in the UK after the issue of guidelines for the use of continuous subcutaneous insulin infusion by NICE in 2008 (Technology Appraisal 151).

METHODS

All centres in the UK, providing pump services to children and young people were invited to participate in an online audit. Audit metrics were aligned to NICE Technology Appraisal 151 and an electronic data collection tool was used.

RESULTS

Of the 176 UK centres identified as providing pump services, 166 (94.3%) participated in the study. A total of 5094 children and young people were identified as using continuous subcutaneous insulin infusion (19% of all paediatric patients with Type 1 diabetes), with a median (range) of 16.9 (0.67-69.4)% per centre. Units had a median of 0.58 consultant sessions, 0.43 full-time equivalent diabetic specialist nurses, and 0.1 full-time equivalent dieticians delivering the pump service. The majority of this time was not formally funded. Families could access 24-h clinical and technical support (83% units), although the delivery varied between consultant, diabetic specialist nurse and company representatives. Only 53% of units ran, or accessed, structured education programmes for continuous subcutaneous insulin infusion use. Most units (86%) allowed continuous subcutaneous insulin infusion use for paediatric inpatients, but only 56% had written guidelines for this scenario. Nine percent of units had encountered funding refusal for a patient fulfilling NICE (Technology Appraisal 151) criteria.

CONCLUSION

The number of children and young people on continuous subcutaneous insulin infusion therapy is consistent with numbers estimated by NICE. There is a worrying lack of funded healthcare professional time. The audit also identified gaps in the provision of structured education and absence of written inpatient guidelines.

Accumulation of gas-phase methamphetamine on clothing, toy fabrics, and skin oil

To better understand methamphetamine exposure and risk for occupants of former residential clandestine methamphetamine laboratories, we measured the dynamic accumulation of methamphetamine in skin oil, cotton and polyester (PE) clothing, upholstery, and toy fabric (substrates) exposed to 15-30 ppb (91-183 μg/m(3)) neutral methamphetamine in air for up to 60 days. The average equilibrium partition coefficients at 30% RH, in units of μg of methamphetamine per gram of substrate per ppb, are 3.0 ± 0.2 for a PE baby blanket, 5.6 ± 3.5 for a PE fabric toy, 3.7 ± 0.2 for a PE shirt, 18.3 ± 8.0 for a PE/cotton upholstery fabric, and 1200 ± 570 in skin oil. The partition coefficients at 60% RH are 4.5 ± 0.4, 5.2 ± 2.1, 4.5 ± 0.6, 36.1 ± 3.6, and 1600 ± 1100 μg/(g ppb), respectively. There was no difference in the partition coefficient for a clean and skin-oil-soiled cotton shirt [15.3 ± 2.1 μg/(g ppb) @ 42 days]. Partition coefficients for skin oil may be sensitive to composition. 'Mouthing' of cloth is predicted to be the dominant exposure pathway [60 μg/(kg body weight*ppb)] for a toddler in former meth lab, and indoor air concentrations would have to be very low (0.001 ppb) to meet the recommended reference dose for children.

PRACTICAL IMPLICATIONS

Gas-phase methamphetamine transfers to and accumulates on clothing, toys and other fabrics significantly increases risk of ingestion of methamphetamine. Current remediation methods should consider measurement of postremediation gas-phase air concentrations of methamphetamine in addition to surface wipe samples.

Self-Reported Interview-Assisted Diet Records Underreport Energy Intake in Maintenance Hemodialysis Patients

OBJECTIVES

Studies suggest that maintenance hemodialysis (MHD) patients report dietary energy intakes (EIs) that are lower than what is actually ingested. Data supporting this conclusion have several important limitations. The present study introduces a novel approach of assessing underreporting of EI in MHD patients.

DESIGN

Comparisons of EI of free-living MHD patients determined from food records to their measured energy needs.

SETTING

Metabolic research ward.

SUBJECTS

Thirteen clinically stable MHD patients with unchanging weights whose EI was assessed by dietitian interview-assisted 3-day food records.

INTERVENTION

EI was compared with (1) patients' resting energy expenditure (REE), measured by indirect calorimetry, and estimated total energy expenditure (TEE) and (2) patients' dietary energy requirements (DER) measured while patients underwent nitrogen balance studies and consumed a constant energy diet in a research ward for a mean duration of 89.5 days. DER was calculated as the actual EI during the research study corrected for changes in body fat and lean body mass measured by Dual X-Ray Absorptiometry.

MAIN OUTCOME MEASURE

Underreporting of EI was determined by an EI:REE ratio <1.27 and an EI:TEE ratio or EI:DEE ratio <1.0.

RESULTS

Seven of the 13 MHD patients studied were male. Patient's ages were 47.7 ± standard deviation 9.7 years; body mass index averaged 25.4 ± 2.8 kg/m2, and dialysis vintage was 53.3 ± 37.1 months. The EI:REE ratio (1.03 ± 0.23) was significantly less than the cutoff value for underreporting of 1.27 (P = .001); 12 of 13 patients had EI:REE ratios <1.27. The mean EI:TEE ratio was significantly less than the cutoff value of 1.0 (0.73 ± 0.17, P < .0001), and 12 MHD patients had EI:TEE ratios <1.0. The EI:DER ratio was also <1.0 (0.83 ± 0.25, P = .012), and 10 MHD had EI:DER ratios <1.0.

CONCLUSIONS

Dietitian interview-assisted diet records by MHD patients substantially underestimate the patient's dietary EI.

The U.K. service level audit of insulin pump therapy in adults

AIMS

The National Institute for Health and Clinical Excellence (NICE) published guidelines for the use of continuous subcutaneous insulin infusion in 2008 (technology appraisal 151). The first U.K.-wide insulin pump audit took place in 2012 with the aim of determining adherence to the guidance issued in NICE technology appraisal 151. The results of the adult service level audit are reported here.

METHODS

All centres providing continuous subcutaneous insulin infusion services to adults with diabetes in the U.K. were invited to participate. Audit metrics were aligned to technology appraisal 151. Data entry took place online using a DiabetesE formatted data collection tool.

RESULTS

One hundred and eighty-three centres were identified as delivering adult continuous subcutaneous insulin infusion services in the U.K., of which 178 (97.3%) participated in the audit. At the time of the audit, 13 428 adults were using insulin pump therapy, giving an estimated prevalence of use of 6%. Ninety-three per cent of centres did not report any barriers in obtaining funding for patients who fulfilled NICE criteria. The mean number of consultant programmed activities dedicated to continuous subcutaneous insulin infusion services was 0.96 (range 0-8), mean whole-time equivalent diabetes specialist nurses was 0.62 (range 0-3) and mean whole-time equivalent dietitian services was 0.3 (range 0-2), of which 39, 61 and 60%, respectively, were not formally funded.

CONCLUSIONS

The prevalence of continuous subcutaneous insulin infusion use in the U.K. falls well below the expectation of NICE (15-20%) and that of other European countries (> 15%) and the U.S.A. (40%). This may be attributable, in part, to lack of healthcare professional time needed for identification and training of new pump therapy users.

Effects of methylnaltrexone in patients with narcotic bowel syndrome: a pilot observational study

BACKGROUND

Narcotic bowel syndrome (NBS) describes disabling chronic severe abdominal pain that worsens despite continuing or escalating doses of opiates. Therapy is very limited.

AIM

To examine effects of blocking peripheral µ-opioid receptors on the symptomatology of patients with NBS and its safety.

METHODS

An open-label observational study was performed in four women with NBS. After a 2-week run-in period, patients were treated for 12 weeks with 8-12 mg methylnaltrexone bromide subcutaneously every other day, increasing to daily if there was poor response. Patient and physician assessment was documented, and patients completed an eight-symptom visual analogue scale weekly and the Functional Assessment of Chronic Illnesses Therapy-Fatigue questionnaire for fatigue. Patients were observed for 4 weeks following withdrawal of the drug.

RESULTS

One patient was unable to tolerate the study medication because of worsening pain after injection, and withdrew. Two showed clear benefit with reduction of symptoms overall, pain, bloating, distension, nausea and tiredness, with improved satisfaction and consistency of bowel actions and fatigue scores. Both reduced analgesic usage. The third had improved ileostomy output and had no episodes of severe bloating, but pain scores remained high. All three worsened after drug withdrawal and requested retreatment. Three experienced abdominal pains of moderate severity for 30-60 min consistently within 5 min of each injection. No other adverse events were experienced.

CONCLUSIONS

Methylnaltrexone has a positive impact on symptoms in women with NBS, although treatment does induce transient pain following its administration. Larger studies are required to examine its efficacy and longer term safety in this patient group.

Survey of general practitioners' attitudes to prescribing statins in different patient groups: a web-based survey

Low rates of statin prescribing have been noted in several major studies of patients with schizophrenia and the aim of this study was to investigate clinicians' attitudes to prescribing statins to different patient groups. The general practitioners (GPs) in Dumfries and Galloway were randomized into two groups. They received an email invitation to a web-based survey. The survey asked for treatment recommendation for three patient vignettes, each with a 10-year cardiovascular risk of 20%. In one group descriptions of the patient included type 1 diabetes, epilepsy and unemployed and in the other group these were replaced by type 2 diabetes, schizophrenia and retired. The questionnaires had no other differences. After three email invites, 53 questionnaires were completed (40% of a potential 133 participants). Statin therapy was recommended by 88% and 85% of respondents for patients with type 1 and type 2 diabetes, respectively; by 37% of respondents for patients with schizophrenia and 31% for patients with epilepsy; by 33% of respondents for retired patients and 23% of respondents for patients who are unemployed. This study demonstrates under-prescribing of statins. This was not worse for patients with schizophrenia as compared with patients with epilepsy. This suggests that the low rates of treatment of metabolic risk factors in patients with schizophrenia are not the result of clinician bias when compared with patients with epilepsy. Clinician bias, however, may reduce the chances of an unemployed patient receiving statin treatment.

A solid phase extraction-liquid chromatographic-tandem mass spectrometry method for determination of concentrations of GDC-0941, a small molecule class I phosphatidylinositide 3-kinase inhibitor, to support clinical development

A solid phase extraction (SPE) liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method for the determination of GDC-0941 concentrations in human plasma has been developed and validated to support clinical development. An Oasis MCX 10mg 96-well SPE plate was used to extract plasma samples (50 μL) and the resulting extracts were analyzed using reverse-phase chromatography and mass spectrometer coupled with a turbo-ionspray interface. The method was validated over the calibration curve range 0.500-500 ng/mL with linear regression and 1/x(2) weighting. Within-run relative standard deviation (%RSD) ranged from 1.5 to 11.5%, while the between-run %RSD varied from 0.0 to 4.4%. The accuracy ranged from 96.0% to 110.0% of nominal for within-run and 98.0% to 108.0% of nominal for between-run at all concentrations including the LLOQ quality control at 0.500 ng/mL. Extraction recovery of GDC-0941 was between 79.0% and 86.2%. Stability of GDC-0941 was established in human plasma for 602 days at -70 °C and 598 days at -20°C, respectively, and established in reconstituted sample extracts for 167 h when stored at room temperature. Internal standard normalized matrix factor was 1.1, demonstrating that the use of the stable-labeled internal standard GDC-0941-d(8) effectively compensated observed matrix effect and resulting in no adverse impact on the quality of the data produced. This assay was used for the determination of GDC-0941 human plasma concentrations over a sufficient time period to determine pharmacokinetic parameters at relevant clinical doses.

The role of continuous subcutaneous insulin infusion therapy in patients with diabetic gastroparesis

AIMS/OBJECTIVE

To describe the effectiveness of continuous subcutaneous insulin infusion (CSII) in patients with symptomatic diabetic gastroparesis and unstable glycaemic control.

METHODS

Data from 26 patients with symptomatic diabetic gastroparesis and unstable glycaemic control using multiple-dose insulin (MDI) regimens, and subsequently managed with CSII, were analysed.

RESULTS

Following initiation of CSII, the median length of inpatient bed days associated with hospital admissions related to gastroparesis and glycaemic instability was reduced from 8.5 (range 0-144) days patient( -1) year( -1) prior to CSII to 0 (range 0-15) days patient( -1) year( -1). The median HbA(1c) reduction with CSII was 1.8% (22 mmol/mol; p < 0.05). The median capillary blood glucose (CBG) with CSII was significantly lower than with MDI: 7.7 mmol/l (range 3.8-15.4 mmol/l) vs 9.8 mmol/l (range 2.3-27 mmol/l), respectively, p < 0.001. Glycaemic variability with CSII was significantly reduced compared with MDI: CBG CV 0.37 vs CV 0.53, respectively, p < 0.001.

CONCLUSIONS/INTERPRETATION

CSII therapy in patients with diabetic gastroparesis results in significant improvement in glycaemic control and reductions in glycaemic variability and number of hospital inpatient bed days.

Ozone-surface reactions in five homes: surface reaction probabilities, aldehyde yields, and trends

Field experiments were conducted in five homes during three seasons (summer 2005, summer 2006 and winter 2007) to quantify ozone-initiated secondary aldehyde yields, surface reaction probabilities, and trends any temporal over a 1.5-year interval. Surfaces examined include living room carpets, bedroom carpets, kitchen floors, kitchen counters, and living room walls. Reaction probabilities for all surfaces for all seasons ranged from 9.4 x 10(-8) to 1.0 x 10(-4). There were no significant temporal trends in reaction probabilities for any surfaces from summer 2005 to summer 2006, nor over the entire 1.5-year period, indicating that it may take significantly longer than this period for surfaces to exhibit any 'ozone aging' or lowering of ozone-surface reactivity. However, all surfaces in three houses exhibited a significant decrease in reaction probabilities from summer 2006 to winter 2007. The total yield of aldehydes for the summer of 2005 were nearly identical to that for summer of 2006, but were significantly higher than for winter 2007. We also observed that older carpets were consistently less reactive than in newer carpets, but that countertops remained consistently reactive, probably because of occupant activities such as cooking and cleaning.

PRACTICAL IMPLICATIONS

Ozone reactions taking place at indoor surfaces significantly influence personal exposure to ozone and volatile reaction products. These field studies show that indoor surfaces only slowly lose their ability to react with ozone over several year time frames, and that this is probably because of a combination of large reservoirs of reactive coatings and periodic additions of reactive coatings in the form of cooking, cleaning, and skin-oil residues. When considering exposure to ozone and its reaction products and in the absence of dramatic changes in occupancy, activities or furnishings, indoor surface reactivity is expected to change very slowly.

The influence of chemical interactions at the human surface on breathing zone levels of reactants and products

Using computational fluid dynamics simulations of an occupant in a ventilated room, we find that breathing zone ozone levels can be substantially lower and ozone reaction products associated with human surfaces (ORPHS) levels considerably higher than room levels. For air exchange rates <3/h, the ratio of the breathing zone to the ozone concentration 1 m from the body (bulk air), r(ozone), ranges from 0.59 to 0.75 for floor or ceiling air supply. ORPHS are enriched in the breathing zone, with concentrations for these conditions ranging from 1.2 to 2.5 greater than bulk air concentrations. At high air exchange rates (>8/h), the breathing zone concentrations approach bulk air concentrations (r(ozone) > 0.9) with a floor supply, whereas large concentration gradients occur between breathing zone and bulk air with a ceiling supply. At these high air exchange rates, ORPHS levels are 1.6-2.0 and 2.9-6.0 times the bulk air concentrations for floor and ceiling supply, respectively. The extent of depletion of ozone or enrichment of ORPHS is large enough that reliance on micro-environmental measurements alone, to assess the intake of ozone or ORPHS, is undesirable.

PRACTICAL IMPLICATIONS

Chemical reactions between ozone and human and clothing surfaces are predicted to significantly reduce ozone concentrations, and increase ozone reaction products associated with human surfaces (ORPHS) concentrations, in the breathing zone, relative to those concentrations in the larger microenvironment of a room. Existing measurements may overestimate ozone exposure and intake in typical indoor environments.

The impact of paediatric tracheostomy on both patient and parent

OBJECTIVE

We set out to assess the impact of paediatric tracheostomy, performed in a central London hospital, on patients and their families.

METHODS

We conducted structured interviews with caregivers of tracheostomised children using the Pediatric Tracheotomy Health Status Instrument during all in-patient admissions for airway endoscopy over a 6-month period.

RESULTS

Completed questionnaires were received from 26 caregivers, 7 (27%) of whose children had been successfully decannulated. Carers reported adverse effects on all aspects of their quality of life, including sleep, relationships, social life and ability to work. The families included in the study had gross household incomes below the mean for SE London. There is a shortfall in the provision of home nursing when compared with the needs of the caregivers.

CONCLUSIONS

Tracheostomy has wide ranging effects on the quality of life of both the patient and their caregivers. We identified the need for better pre-operative preparation where possible, and greater support for such families in the community.

Incomplete resection of focal cortical dysplasia is the main predictor of poor postsurgical outcome

BACKGROUND

Focal cortical dysplasia (FCD) is recognized as the major cause of focal intractable epilepsy in childhood. Various factors influencing postsurgical seizure outcome in pediatric patients with FCD have been reported.

OBJECTIVE

To analyze different variables in relation to seizure outcome in order to identify prognostic factors for selection of pediatric patients with FCD for epilepsy surgery.

METHODS

A cohort of 149 patients with histologically confirmed mild malformations of cortical development or FCD with at least 2 years of postoperative follow-up was retrospectively studied; 113 subjects had at least 5 years of postoperative follow-up. Twenty-eight clinical, EEG, MRI, neuropsychological, surgical, and histopathologic parameters were evaluated.

RESULTS

The only significant predictor of surgical success was completeness of surgical resection, defined as complete removal of the structural MRI lesion (if present) and the cortical region exhibiting prominent ictal and interictal abnormalities on intracranial EEG. Unfavorable surgical outcomes are mostly caused by overlap of dysplastic and eloquent cortical regions. There were nonsignificant trends toward better outcomes in patients with normal intelligence, after hemispherectomy and with FCD type II. Other factors such as age at seizure onset, duration of epilepsy, seizure frequency, associated pathologies including hippocampal sclerosis, extent of EEG and MRI abnormalities, as well as extent and localization of resections did not influence outcome. Twenty-five percent of patients changed Engel's class of seizure outcome after the second postoperative year.

CONCLUSIONS

The ability to define and fully excise the entire region of dysplastic cortex is the most powerful variable influencing outcome in pediatric patients with focal cortical dysplasia.

Role of internal chain dynamics on the rupture kinetic of adhesive contacts

We study the forced rupture of adhesive contacts between monomers that are not covalently linked in a Rouse chain. When the applied force (f) to the chain end is less than the critical force for rupture (f{c}), the reversible rupture process is coupled to the internal Rouse modes. If f/f{c}>1 the rupture is irreversible. In both limits, the nonexponential distribution of contact lifetimes, which depends sensitively on the location of the contact, follows the double-exponential (Gumbel) distribution. When two contacts are well separated along the chain, the rate limiting step in the sequential rupture kinetics is the disruption of the contact that is in the chain interior. If the two contacts are close to each other, they cooperate to sustain the stress, which results in an "all-or-none" transition.

Effects of dynamic upper-body exercise on lower-limb isometric endurance

Following preliminary indications that in some individuals arm exercise enhanced rather than reduced simultaneous leg endurance, ten young men and women performed three forms of intermittent work to volitional exhaustion, under duty cycles of 45 s work, 15 s rest. The protocols were as follows: (A) knee extensions at 30% maximum voluntary contraction (MVC); (B) 30% MVC knee extensions combined with arm cranking at 130% of their own lactate threshold; (C) combined 30% MVC knee extensions and arm cranking at 20% of their own lactate threshold. Heart rate, oxygen uptake (VO(2)), and blood lactate concentration were among the variables recorded throughout. All physiological indicators of demand were substantially higher in protocol B than in protocols A or C [heart rate: (A) 154 beats . min(-1), (B) 171 beats . min(-1), (C) 150 beats . min(-1); VO(2): (A) 11.9 ml . kg(-1) . min(-1), (B) 21.7 ml . kg(-1) . min(-1), (C) 14.2 ml . kg(-1) . min(-1); blood lactate concentration: (A) 3.3 mmol . l(-1), (B) 5.1 mmol . l(-1), (C) 2.8 mmol . l(-1)], yet there were no significant differences (P > 0.05) in the endurance times between the three conditions [(A) 11.43 min, (B) 11.1 min, (C) 10.57 min] and seven participants endured longest in protocol B. Results from protocol (C) cast doubt on explanations in terms of psychological distraction. We suggest that lactic acid produced by the arms is shuttled to the legs and acts there either as a supplementary fuel source or as an antagonist to the depressing effects of increased potassium concentration.

The shape of a flexible polymer in a cylindrical pore

We calculate the mean end-to-end distance R of a self-avoiding polymer encapsulated in an infinitely long cylinder with radius D. A self-consistent perturbation theory is used to calculate R as a function of D for impenetrable hard walls and soft walls. In both cases, R obeys the predicted scaling behavior in the limit of large and small D. The crossover from the three-dimensional behavior (D --> infinity) to the fully stretched one-dimensional case (D --> 0) is nonmonotonic. The minimum value of R is found at D approximately 0.46R(F), where R(F) is the Flory radius of R at D --> infinity. The results for soft walls map onto the hard wall case with a larger cylinder radius.

Effect of intensive dietetic interventions on weight and glycaemic control in overweight men with Type II diabetes: a randomised trial

OBJECTIVE

To investigate the effectiveness of intensive innovative methods for implementing dietary prescriptions on weight management and glycaemic control in overweight men with Type II diabetes.

DESIGN

A randomised clinical trial with a 12-week intervention period - three isocaloric dietary intervention groups (intermittent energy restriction, pre-portioned meals and self-selected meals) each with weekly dietitian contact - and a follow-up visit after 18 months.

SUBJECTS

A total of 51 men with Type II diabetes (mean age 54 y, mean body mass index (BMI) 31.7 kg/m(2)).

MEASUREMENTS

Weight, body composition, waist circumference, glycaemic control (HbA(1c)) and blood lipids.

RESULTS

For all subjects, intensive diet therapy over the 12-week intervention period resulted in a mean reduction in energy intake of 2360+/-2780 kJ/day (564+/-665 kcal/day) and significant reductions in weight (6.4+/-4.6 kg), waist circumference (8.1+/-4.6 cm), percent body fat (1.9+/-1.5%), HbA(1c) (1.0+/-1.4%) and triglyceride levels (0.3+/-0.6 mmol/l) compared to baseline levels. Intervention group did not affect clinical outcomes, with the exception of percent body fat. A total of 27 (52.9%) subjects attended the 18-month follow-up visit. At this visit, none of the improvements in clinical parameters was maintained, with all parameters returning to preintervention levels.

CONCLUSIONS

: A dietary prescription of 6000-7000 kJ/day (1400-1700 kcal/day) was effective in achieving a 6% weight loss and improving glycaemic control. The method of implementation made no difference to the outcomes between groups at 12 weeks or 18 months. Thus, we propose that it was the intensive weekly contact with a health professional in combination with moderate energy restriction that facilitated the successful short-term results seen.

Levels and risk assessment for humans and ecosystems of platinum-group elements in the airborne particles and road dust of some European cities

Traffic is the main source of platinum-group element (PGE) contamination in populated urban areas. There is increasing concern about the hazardous effects of these new pollutants for people and for other living organisms in these areas. Airborne and road dusts, as well as tree bark and grass samples were collected at locations in the European cities of Göteborg (Sweden), Madrid (Spain), Rome (Italy), Munich (Germany), Sheffield and London (UK). Today, in spite of the large number of parameters that can influence the airborne PGE content, the results obtained so far indicate significantly higher PGE levels at traffic sites compared with the rural or non-polluted zones that have been investigated (background levels). The average Pt content in airborne particles found in downtown Madrid, Göteborg and Rome is in the range 7.3-13.1 pg m(-3). The ring roads of these cities have values in the range 4.1-17.7 pg m(-3). In Munich, a lower Pt content was found in airborne particles (4.1 pg m(-3)). The same tendency has been noted for downtown Rh, with contents in the range 2.2-2.8 pg m(-3), and in the range 0.8-3.0 and 0.3 pg m(-3) for motorway margins in Munich. The combined results obtained using a wide-range airborne classifier (WRAC) collector and a PM-10 or virtual impactor show that Pt is associated with particles for a wide range of diameters. The smaller the particle size, the lower the Pt concentration. However, in particles <PM-10, some of the highest values correspond to the fraction <0.39 microm. Considering an average Pt content in all particles of approximately 15 pg m(-3), which is representative for all countries and environmental conditions, the tracheobronchial fraction represents approximately 10% and the alveolar fraction approximately 8% of the total particles suspended in air. However, from the environmental risk point of view, an exposure to PGEs in traffic-related ambient air is at least three orders of magnitude below the levels for which adverse health effects might theoretically occur (of approx. 100 ng m(-3)). Therefore, today inhalation exposure to PGEs from automotive catalysts does not seem to pose a direct health risk to the general population. Even though the data available today indicate no obvious health effects, there are still a number of aspects related to PGEs and catalysts that justify further research. First, continual monitoring of changes in PGE levels in air and road dust is warranted, to make sure that there is no dramatic increase from today's levels. Secondly, more detailed information on the chemical composition of the PGE-containing substances or complexes leaving the catalyst surface and the size distribution of the PGE-containing particles released during driving will facilitate a more in-depth human risk assessment.

Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters

A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80,000 km. Two were gasoline engine catalysts (Pt-Pd-Rh and Pd-Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one-two orders of magnitude) for the content of noble metals emitted. The samples collected from 30,000-80,000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment.

Characterization of the mouse beta defensin 1, Defb1, mutant mouse model

Beta defensins are small cationic antimicrobial peptides present in the respiratory system which have been proposed to be dysfunctional in the environment of the cystic fibrosis lung. Defb1, a murine homologue to the human beta defensins, has also been found to be expressed in the respiratory system and, in order to examine the function of beta defensins in vivo, gene targeting was used to generate Defb1-deficient (Defb1(tm1Hgu)/Defb1(tm1Hgu) [Defb1(-/-)]) mice. The Defb1 synthetic peptide was shown to have a salt-sensitive antimicrobial activity that was stronger against Staphylococcus aureus than against Escherichia coli or Pseudomonas aeruginosa. Defb1(-/-) mice were found, however, to be effective in the clearance of the cystic fibrosis relevant pathogen S. aureus from the airways after nebulization. Although no overt deleterious phenotype was evident in the Defb1(-/-) mice, the number of mutant mice found to harbor bacteria of the Staphylococcus species in the bladder was significantly higher (P = 0.008) than that of controls, suggesting a role for these peptides in resistance to urinary tract infection.