ARF suppression by MYC but not MYCN confers increased malignancy of aggressive pediatric brain tumors

Medulloblastoma, the most common malignant pediatric brain tumor, often harbors MYC amplifications. Compared to high-grade gliomas, MYC-amplified medulloblastomas often show increased photoreceptor activity and arise in the presence of a functional ARF/p53 suppressor pathway. Here, we generate an immunocompetent transgenic mouse model with regulatable MYC that develop clonal tumors that molecularly resemble photoreceptor-positive Group 3 medulloblastoma. Compared to MYCN-expressing brain tumors driven from the same promoter, pronounced ARF silencing is present in our MYC-expressing model and in human medulloblastoma. While partial Arf suppression causes increased malignancy in MYCN-expressing tumors, complete Arf depletion promotes photoreceptor-negative high-grade glioma formation. Computational models and clinical data further identify drugs targeting MYC-driven tumors with a suppressed but functional ARF pathway. We show that the HSP90 inhibitor, Onalespib, significantly targets MYC-driven but not MYCN-driven tumors in an ARF-dependent manner. The treatment increases cell death in synergy with cisplatin and demonstrates potential for targeting MYC-driven medulloblastoma.

Dormant SOX9-Positive Cells Facilitate MYC-Driven Recurrence of Medulloblastoma

Relapse is the leading cause of death in patients with medulloblastoma, the most common malignant pediatric brain tumor. A better understanding of the mechanisms underlying recurrence could lead to more effective therapies for targeting tumor relapses. Here, we observed that SOX9, a transcription factor and stem cell/glial fate marker, is limited to rare, quiescent cells in high-risk medulloblastoma with MYC amplification. In paired primary-recurrent patient samples, SOX9-positive cells accumulated in medulloblastoma relapses. SOX9 expression anti-correlated with MYC expression in murine and human medulloblastoma cells. However, SOX9-positive cells were plastic and could give rise to a MYC high state. To follow relapse at the single-cell level, an inducible dual Tet model of medulloblastoma was developed, in which MYC expression was redirected in vivo from treatment-sensitive bulk cells to dormant SOX9-positive cells using doxycycline treatment. SOX9 was essential for relapse initiation and depended on suppression of MYC activity to promote therapy resistance, epithelial-mesenchymal transition, and immune escape. p53 and DNA repair pathways were downregulated in recurrent tumors, whereas MGMT was upregulated. Recurrent tumor cells were found to be sensitive to treatment with an MGMT inhibitor and doxorubicin. These findings suggest that recurrence-specific targeting coupled with DNA repair inhibition comprises a potential therapeutic strategy in patients affected by medulloblastoma relapse.

SIGNIFICANCE

SOX9 facilitates therapy escape and recurrence in medulloblastoma via temporal inhibition of MYC/MYCN genes, revealing a strategy to specifically target SOX9-positive cells to prevent tumor relapse.

MODL-31. PHOTORECEPTOR-POSITIVE PROGENITORS PUTATIVE CELLS OF ORIGIN IN MYC-DRIVEN GROUP 3 MEDULLOBLASTOMA

The cell of origin of Group 3 medulloblastoma, the most malignant medulloblastoma subgroup, is currently unknown and remains controversial. Transcriptional profiling has revealed that Group 3 medulloblastomas are characterized by elevated expression of a photoreceptor program, which has not been described in the normal cerebellar development but is well characterized in the developing retina and pineal gland. We used lineage tracing and single-cell sequencing to compare normal brain development with tumor development in our previously generated MYC-driven transgenic mouse model (GMYC), where mice spontaneously develop Group 3 medulloblastoma after 4-6 months of age. We found that tumor cells emerged from progenitor cells where MYC overexpression drove the transformation of immature progenitor cells with photoreceptor pathway activity. Our data suggest that MYC-driven Group 3 medulloblastoma originates from progenitor cells expressing a photoreceptor program, which has implications for future research and the development of novel treatments targeting this devastating childhood malignancy.

Novel cancer gene discovery using a forward genetic screen in RCAS-PDGFB-driven gliomas

BACKGROUND

Malignant gliomas, the most common malignant brain tumors in adults, represent a heterogeneous group of diseases with poor prognosis. Retroviruses can cause permanent genetic alterations that modify genes close to the viral integration site.

METHODS

Here we describe the use of a high-throughput pipeline coupled to the commonly used tissue-specific retroviral RCAS-TVA mouse tumor model system. Utilizing next-generation sequencing, we show that retroviral integration sites can be reproducibly detected in malignant stem cell lines generated from RCAS-PDGFB-driven glioma biopsies.

RESULTS

A large fraction of common integration sites contained genes that have been dysregulated or misexpressed in glioma. Others overlapped with loci identified in previous glioma-related forward genetic screens, but several novel putative cancer-causing genes were also found. Integrating retroviral tagging and clinical data, Ppfibp1 was highlighted as a frequently tagged novel glioma-causing gene. Retroviral integrations into the locus resulted in Ppfibp1 upregulation, and Ppfibp1-tagged cells generated tumors with shorter latency on orthotopic transplantation. In human gliomas, increased PPFIBP1 expression was significantly linked to poor prognosis and PDGF treatment resistance.

CONCLUSIONS

Altogether, the current study has demonstrated a novel approach to tagging glioma genes via forward genetics, validating previous results, and identifying PPFIBP1 as a putative oncogene in gliomagenesis.

MEDB-55. Single-cell transcriptomics reveals progenitor cells expressing a photoreceptor program as putative cells origin of MYC-driven Group 3 Medulloblastoma

Brain tumors are the leading cause of childhood cancer-related death. Medulloblastoma is the most common malignant pediatric brain tumor with about 70% survival. Medulloblastoma comprises four distinct subgroups respective of genomic and molecular drivers influencing tumorigenesis. It has been established that despite being considered a single disease entity, each subgroup arises from a distinct population of cells found within unique compartments of the developing brain. The cell of origin of Group 3 medulloblastoma, the most malignant medulloblastoma subgroups, is currently unknown and remains controversial. Transcriptional profiling has revealed that Group 3 medulloblastomas are characterized by elevated expression of a photoreceptor program, which has not been described in the normal cerebellar development but is well characterized in the developing pineal gland and retinal. By investigating and comparing brain and tumor development between our previously developed medulloblastoma mice model (GMYC), where mice spontaneously develop Group 3 medulloblastoma after 4-6 months of age, and their control counterparts, we found that tumor cells emerged from progenitor cells where MYC overexpression drove the transformation of immature progenitor cells expressing a photoreceptor program. Our data suggest that MYC-driven Group 3 medulloblastoma originates from progenitor cells expressing a photoreceptor program, which has implications for future research and the development of novel treatments targeting this devastating childhood malignancy.

TMOD-25. LATENT SOX9-POSITIVE CELLS BEHIND MYC-DRIVEN MEDULLOBLASTOMA RELAPSE

Tumor recurrence developing from therapy resistance, immune escape and metastasis is the leading cause of death in medulloblastoma, the most frequent malignant pediatric brain tumor. Amplification of MYC genes is the most common genetic alteration in Group 3 and Group 4 subgroups that constitute two thirds of medulloblastoma. SOX9 is a transcription factor present in stem cells in the normal brain but is limited to rare, quiescent cells in medulloblastoma patients with MYC gene amplifications. By studying paired primary-recurrent patient samples and patient-derived xenografts we here identified significant accumulation of SOX9-positive cells in Group 3 and Group 4 relapses. To follow relapse at the single cell level we developed an inducible dual Tet model of MYC-driven MB, where MYC was re-directed from the treatment-sensitive bulk cells to resistant, dormant SOX9-positive cells by doxycycline. In this model, distant recurrent tumors and spinal metastases developed. SOX9 promoted immune escape, DNA repair suppression and was essential for recurrence. Tumor cell dormancy was non-hierarchical, migratory and depended on MYC suppression by SOX9 to promote relapse. By using computational modeling and treatment we also showed how doxorubicin and MGMT inhibitors were specifically targeting recurrent cells that could be of potential use in future treatments for patients affected by these fatal relapses.

TMOD-28. MYC GENERATES AGGRESSIVE MEDULLOBLASTOMA BY HSP90 PATHWAY ACTIVATION AND ARF SILENCING

Medulloblastoma, the most common malignant pediatric brain tumor, often shows amplification or overexpression of the MYC transcription factor and arises in the presence of a functional p53 tumor suppressor protein. To elucidate the mechanism behind this inexplicable tumor development we generated an inducible, immunocompetent transgenic mouse model of MYC-expressing medulloblastoma. Aggressive tumors developed clonally in the presence of an unaltered p53 gene that molecularly resembled Group 3 medulloblastoma. Compared to MYCN-expressing medulloblastoma driven from the same promoter, we instead discovered pronounced and MIZ1-independent silencing of the ARF suppressor, which was also suppressed in MYC-amplified as compared to MYCN-amplified human medulloblastoma. While MYCN-driven tumor malignancy was more sensitive to ARF depletion, it dramatically increased metastatic spread of MYC-driven tumors. DNMT inhibition could restore ARF levels in MYC-expressing tumors but did not show any therapeutic advantage in tumors in vivo. Bioinformatics analysis further showed a strong correlation of the HSP90 pathway with MYC in human Group 3 MB and in the MYC-driven mouse model. The HSP90 inhibitor Onalespib showed significant selectivity for targeting MYC-driven as compared to MYCN-driven tumors. The drug promoted ARF restoration and increased the survival in our animal model which suggests that it could be potentially used in the treatment of MYC-driven ARF-silenced brain cancer patients.

EMBR-07. MYC BUT NOT MYCN GENERATES AGGRESSIVE GROUP 3 MEDULLOBLASTOMA BY ARF PATHWAY SUPPRESSION

Medulloblastoma (MB), the most common malignant pediatric brain tumor, often harbor MYC amplifications and arise in the presence of a functional p53 suppressor protein. To elucidate the mechanism behind this inexplicable tumor development we generated an inducible, immunocompetent transgenic mouse model of MYC-driven MB. Tumors driven from the glutamate transporter promoter molecularly resembled aggressive Group 3 MB driven by an enriched photoreceptor program. They developed embryonically in a monoclonal fashion in the presence of a functional unmutated p53 gene. Compared to MYCN-expressing MB driven from the same promoter, we discovered pronounced silencing of the ARF suppressor upstream of p53. We similarly found significant methylation of the ARF promoter in MYC-amplified as compared to MYCN-amplified human MB samples. While MYCN-driven tumor malignancy was more sensitive to ARF depletion, it dramatically increased metastatic spread of MYC-driven tumors. DNMT inhibition could restore ARF levels in MYC-expressing tumors but did not show any therapeutic advantage in tumors in vivo. Computational modeling suggested the HSP90 protein to act as a more specific target and ARF could indeed be restored by the HSP90 inhibitor onalespib that promoted increased survival in our inducible animal model suggesting that HSP90 inhibition could be potentially used in patients affected by MYC-driven ARF-silenced cancer.

MBRS-10. QUIESCENT SOX9-POSITIVE CELLS BEHIND MYC DRIVEN MEDULLOBLASTOMA RECURRENCE

Tumor recurrence is the leading cause of death in medulloblastoma, the most frequent malignant pediatric brain tumor. Recurrence occurs when subpopulations of cancer cells evade standard therapy by acquiring features of immune escape, metastatic spread, and treatment resistance. The transcription factor SOX9 correlated with treatment resistance and dissemination in aggressive Group 3 medulloblastoma. By studying paired primary-recurrent medulloblastoma samples and patient-derived xenograft models, we identified rare SOX9-positive slow-cycling, therapy-resistant tumor cells that accumulate in relapses and in metastases. In an inducible transgenic Group 3 tumor model, doxycycline treatment kills all tumor cells by turning MYC off. However, when MYC expression was redirected to the SOX9 promoter, recurrences from rare, dormant SOX9-positive cells developed with 100% penetrance. Expression profiling revealed that recurrences were more inflammatory, metastatic, and showed elevated MGMT methyltransferase levels which depleted recurrent cells when selectively inhibited. Our model explains how recurrences develop from SOX9-induced quiescence in MYC-driven brain cancer.

Humanized Stem Cell Models of Pediatric Medulloblastoma Reveal an Oct4/mTOR Axis that Promotes Malignancy

Medulloblastoma (MB), the most frequent malignant childhood brain tumor, can arise from cellular malfunctions during hindbrain development. Here we generate humanized models for Sonic Hedgehog (SHH)-subgroup MB via MYCN overexpression in primary human hindbrain-derived neuroepithelial stem (hbNES) cells or iPSC-derived NES cells, which display a range of aggressive phenotypes upon xenografting. iPSC-derived NES tumors develop quickly with leptomeningeal dissemination, whereas hbNES-derived cells exhibit delayed tumor formation with less dissemination. Methylation and expression profiling show that tumors from both origins recapitulate hallmarks of infant SHH MB and reveal that mTOR activation, as a result of increased Oct4, promotes aggressiveness of human SHH tumors. Targeting mTOR decreases cell viability and prolongs survival, showing the utility of these varied models for dissecting mechanisms mediating tumor aggression and demonstrating the value of humanized models for a better understanding of pediatric cancers.

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Human iPSC-derived or primary neuroepithelial stem cells can be transformed by MYCN

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MYCN drives infant SHH medulloblastoma with clinically relevant features

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Epigenetically regulated Oct4 promotes mTOR hyperactivation in infant SHH tumors

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mTOR inhibition efficiently targets metastatic SHH medulloblastoma models and PDXs

BET and Aurora Kinase A inhibitors synergize against MYCN-positive human glioblastoma cells

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults. Patients usually undergo surgery followed by aggressive radio- and chemotherapy with the alkylating agent temozolomide (TMZ). Still, median survival is only 12–15 months after diagnosis. Many human cancers including GBMs demonstrate addiction to MYC transcription factor signaling and can become susceptible to inhibition of MYC downstream genes. JQ1 is an effective inhibitor of BET Bromodomains, a class of epigenetic readers regulating expression of downstream MYC targets. Here, we show that BET inhibition decreases viability of patient-derived GBM cell lines. We propose a distinct expression signature of MYCN-elevated GBM cells that correlates with significant sensitivity to BET inhibition. In tumors showing JQ1 sensitivity, we found enrichment of pathways regulating cell cycle, DNA damage response and repair. As DNA repair leads to acquired chemoresistance to TMZ, JQ1 treatment in combination with TMZ synergistically inhibited proliferation of MYCN-elevated cells. Bioinformatic analyses further showed that the expression of MYCN correlates with Aurora Kinase A levels and Aurora Kinase inhibitors indeed showed synergistic efficacy in combination with BET inhibition. Collectively, our data suggest that BET inhibitors could potentiate the efficacy of either TMZ or Aurora Kinase inhibitors in GBM treatment.

FBW7 suppression leads to SOX9 stabilization and increased malignancy in medulloblastoma

SOX9 is a master transcription factor that regulates development and stem cell programs. However, its potential oncogenic activity and regulatory mechanisms that control SOX9 protein stability are poorly understood. Here, we show that SOX9 is a substrate of FBW7, a tumor suppressor, and a SCF (SKP1/CUL1/F‐box)‐type ubiquitin ligase. FBW7 recognizes a conserved degron surrounding threonine 236 (T236) in SOX9 that is phosphorylated by GSK3 kinase and consequently degraded by SCF^FBW7α. Failure to degrade SOX9 promotes migration, metastasis, and treatment resistance in medulloblastoma, one of the most common childhood brain tumors. FBW7 is either mutated or downregulated in medulloblastoma, and in cases where FBW7 mRNA levels are low, SOX9 protein is significantly elevated and this phenotype is associated with metastasis at diagnosis and poor patient outcome. Transcriptional profiling of medulloblastoma cells expressing a degradation‐resistant SOX9 mutant reveals activation of pro‐metastatic genes and genes linked to cisplatin resistance. Finally, we show that pharmacological inhibition of PI3K/AKT/mTOR pathway activity destabilizes SOX9 in a GSK3/FBW7‐dependent manner, rendering medulloblastoma cells sensitive to cytostatic treatment.

Abstract 2473: Combined BET-bromodomain and CDK2 inhibition in MYC-driven medulloblastoma

Misexpression of MYC genes (MYC and MYCN) occurs commonly in medulloblastoma (MB), the most frequent malignant childhood brain tumor. We previously showed that tumors are addicted to MYCN and that MYCN stabilization is required for MB development in mice (Swartling et al, Genes & Dev, 2010; Cancer Cell, 2012). Targeted MYCN suppression completely depleted MYCN-driven MB cells in vivo. Immediate transcriptional changes from such MYCN blockade were found by RNA-Seq and showed similarities to changes that occurred after CDK2 suppression or when inhibiting BET bromodomains. CDK2 and BET inhibitors both inhibited MYC protein expression and effectively induced cell cycle arrest or apoptosis. Compared with either agent alone a sustained combination treatment over 7-10 days displayed synergy and effectively abolished tumor cell proliferation in vitro. The combined treatment further reduced tumor growth in orthotopical MB transplants and significantly prolonged survival as compared to single agent therapy. Our data suggest that dual inhibition of CDK2 and BET Bromodomains could be a novel treatment approach in suppressing medulloblastoma by targeting MYC proteins.

Citation Format: Sara Bolin, Anna Borgenvik, Camilla Persson, Gabriela Rosén, Anders Sundström, Jun Qi, James E. Bradner, William A. Weiss, Yoon-Jae Cho, Holger Weishaupt, Fredrik J. Swartling. Combined BET-bromodomain and CDK2 inhibition in MYC-driven medulloblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2473.

A Review of Video Exposure Monitoring as an Occupational Hygiene Tool

This study reviews use of video exposure monitoring (VEM, also known as PIMEX) as an occupational hygiene tool since its inception in the mid-1980s. VEM involves the combination of real-time monitoring instruments, usually for gases/vapours and dust, with video of the worker's activities. VEM is an established method used by practitioners in different countries. The technical aspects of these VEM systems are described, then applications of VEM are discussed, focussing on task analysis, training (risk communication), encouraging worker participation in and motivation for improvements in the workplace environment and occupational hygiene research. The experiences from these applications are used to illustrate how exposure visualization with video can act as a catalyst, initiating a change process in the workplace. Finally, the role of VEM as a workplace improvement tool, now and in the future, is discussed.

Common pathways in mental imagery and pain perception: an fMRI study of a subject with an amputated arm

The present paper reviews data from two previous studies in our laboratory, as well as some additional new data, on the neuronal representation of movement and pain imagery in a subject with an amputated right arm. The subject imagined painful and non-painful finger movements in the amputated stump while being in a MRI scanner, acquiring EPI-images for fMRI analysis. In Study I (Ersland et al., 1996) the Subject alternated tapping with his intact left hand fingers and imagining "tapping" with the fingers of his amputated right arm. The results showed increased neuronal activation in the right motor cortex (precentral gyrus) when tapping with the fingers of the left hand, and a corresponding activation in the left motor cortex when imagining tapping with the fingers of the amputated right arm. Finger tappings of the intact left hand fingers also resulted in a larger activated precentral area than imagery "finger tapping" of the amputated right arm fingers. In Study II (Rosen et al., 2001 in press) the same subject imagining painful and pleasurable finger movements, and still positions of the fingers of the amputated arm. The results showed larger activations over the motor cortex for movement imagining versus imagining the hand being in a still position, and larger activations over the sensory cortex when imagining painful experiences. It can therefore be concluded that not only does imagery activate the same motor areas as real finger movements, but also that adding instructions of pain together with imaging moving the fingers intensified the activation compared with adding instructions about non-painful experiences. From these studies, it is clear that areas activated during actual motor execution to a large extent also are activated during mental imagery of the same motor commands. In this respect the present studies add to studies of visual imagery that have shown a similar correspondence in activation between actual object perception and imagery of the same object.

Surface contamination to UV-curable acrylates in the furniture and parquet industry

Surface contamination to ultraviolet radiation curable coatings (UV coatings), used increasingly in the parquet and furniture industry, is a matter of concern as a source for skin contamination. UV coatings contain chemically and biologically reactive acrylates, well known as skin contact irritants and sensitizers. Surface contamination may spread secondarily to equipment and other unexpected areas even outside the workplace. Yet, studies concerning this type of contamination are lacking due to lack of suitable sampling methods. Surface contamination of the work environment with risk for skin exposure to UV coating was measured employing a quantitative adhesive tape sampling method developed for this purpose. A pilot study was first performed at three workplaces to evaluate the contamination. In the main study, we wanted to locate and identify in detail the surface contamination of areas where problems exist, and to determine the extent of the problem. Measurements were performed at seven workplaces on two separate workdays (round 1 and 2) within a six-month period. Samples were collected from the workplaces based on the video monitoring of skin contact frequency with the surfaces and categorized into three groups to analyze risk. The pilot study indicated that surface contamination to TPGDA containing UV coatings was common, found in 76 percent of the surfaces, and varied with a maximum of 909 microg TPGDA 10 cm(-2) sampling area. In the main study TPGDA was found in 153 out of 196 collected samples (78.1%); for round one 78.1 percent (82 out of 105 samples) and for round two 78.0 percent (71 out of 91 samples). The average TPGDA mass on positive surface samples was on the first round 2,247 +/- 7,462 microg, and on the second round 2,960 +/- 4,590 microg. We conclude that surface contamination to uncured UV coatings at UV-curing lines is common and this involves a risk for harmful, unintentional skin exposure to acrylates.

Different brain areas activated during imagery of painful and non-painful 'finger movements' in a subject with an amputated arm

The purpose of the present study was to investigate differences in brain activation with functional magnetic resonance imaging (fMRI) during imagery of painful and non-painful 'finger movements' and 'hand positioning' in a subject with an amputated arm. The subject was a right-handed man in his mid-thirties who lost his right arm just above the elbow in a car-train accident. MRI was performed with a 1.5 T Siemens Vision Plus scanner. The basic design involved four conditions: imagining 'painful finger movements', 'non-painful finger movements', 'painful hand positioning', 'non-painful hand positioning'. Imagery of finger movements uniquely activated the contralateral primary motor cortex which contains the classic 'hand area'. The lateral part of the anterior cerebellar lobe was also activated during imagery of finger movements. Imagery of pain uniquely activated the somatosensory area, and areas in the left insula and bilaterally in the ventral posterior lateral nucleus of the thalamus. It is suggested that the insula and thalamus may involve neuronal pathways that are critical for mental processing of pain-related experiences, which may relate to a better understanding of the neurobiology of phantom limb pain.

Neurophysiological processes underlying the phantom limb pain experience and the use of hypnosis in its clinical management: an intensive examination of two patients

In a pilot study with 2 patients suffering from phantom limb pain (PLP), hypnotic suggestions were used to modify and control the experience of the phantom limb, and positron emission tomography (PET) was used to index underlying pathways and areas involved in the processing of phantom limb experience (PLE) and PLP. The patients' subjective experiences of pain were recorded in a semistructured protocol. PET results demonstrated activation in areas known to be responsible for sensory and motor processing. The reported subjective experiences of PLP and movement corresponded with predicted brain activity patterns. This work helps to clarify the central nervous system correlates of phantom limb sensations, including pain. It further suggests that hypnosis can be incorporated into treatment protocols for PLP.

Workers' dermal exposure to UV-curable acrylates in the furniture and Parquet industry

The use of ultraviolet radiation-curable coatings (UV-coatings) has increased rapidly in the parquet and furniture industry. Work with UV-coatings involves risk from skin exposure to chemically reactive, concentrated acrylates that are known skin contact irritants and sensitizers. Yet, the methods and tools for measuring and quantifying dermal exposure from hazardous chemicals directly on the skin are limited and methods to measure skin exposure to UV-coatings in occupational or environmental settings have been lacking. Skin exposure to UV-coatings was measured employing a quantitative tape stripping method that we have developed for this purpose. A pilot study was performed at three workplaces. In the main study, workers' skin exposure to uncured UV-coatings was measured at seven workplaces and on two separate workdays (rounds 1 and 2) within a six-month period to determine exposure variation. Skin exposure was measured at four standardized sites on the hand, 3-4 times per work shift. The forehead was sampled once. A questionnaire was carried out with the workers in both rounds to find out factors that can affect skin exposure to UV-coatings. The pilot study indicated that both skin and surface contamination to TPGDA-containing UV-coatings were common and varied up to 2110 microgram on the sampling area of 10cm(2). In the main study skin contamination due to TPGDA was found on 16 of 23 workers, at 6 out of the 7 workplaces, and from 36 (5. 4%) of the 664 samples. In round one 8.6% (n=383) of the samples contained TPGDA and in round two 1.1 % (n=281). The average TPGDA mass on all the positive samples (n=36) was 30.4+/-77.0 microgram for the first and second rounds alone this mass was 30.6+/-80 (n=33) and 28.3+/-16.5 microgram (n=3), respectively. Despite the limited sampling area and sampling sites, we could find residues of TPGDA at all sampling times, even at the beginning of the work shift. This may be due to transfer of UV-coatings through contaminated equipment, shoes and surfaces. Our study indicates that there is a risk of harmful skin exposure to UV-coatings in the furniture and parquet industry.

A method for measuring dermal exposure to multifunctional acrylates

UV-curable acrylates are used increasingly for coating wood surfaces in the furniture industry. One of the active components, tripropylene glycol diacrylate (TPGDA), is known to be both an allergen and irritant to the skin. Methods to measure dermal exposure to skin irritants and allergens, such as acrylates, are insufficient for exposure assessment and there is none for this compound. The aim of this investigation was to develop a skin and surface sampling method, based on tape stripping, and a gas chromatographic method for quantitative analysis for assessing occupational skin exposure to multifunctional acrylates. Twelve adhesives were tested for their efficiency to remove TPGDA and UV-coating from a glass surface, the skin of guinea pigs and human volunteers employing the tape-stripping method in order to find the best performing tape. Variables that affect removal efficiency such as the applied dose and its retention time on the skin, tape adhesion time on the skin, and the number of strippings required to detect the contaminant from the skin were studied. Fixomull tape performed the best during sampling and analysis and had the most consistent removal efficiencies for the studied substances. The average removal efficiency with a single stripping at the 2 microliters TPGDA exposed skin sites was 85% (RSD = 14.1), and for UV-resin exposed sites 63% (RSD = 20.2). The results indicated that this method can be used for measuring dermal exposure to multifunctional acrylates efficiently, accurately, and economically. This method provides a sensitive and powerful tool for the assessment of dermal exposure to multifunctional acrylates both from the skin and from other contaminated surfaces in occupational field settings.

Effect of nasal lavage on nasal symptoms and physiology in wood industry workers

Nasal complaints and impaired nasal physiology are common in various occupational environments. Saline lavage has been recommended as treatment but has not yet been sufficiently evaluated. In this cross-sectional study of 45 wood industry workers, a significant decrease in nasal symptoms (such as obstruction, posterior secretions, itching, irritation and sneezing) was seen after a 3-week treatment with Rhinomer, which contains de-ionized, sterilized, isotonic seawater. Nasal peak expiratory flow (NPEF), especially in workers with nasal complaints, and nasal mucociliary clearance also improved significantly. The treatment, according to participants, was simple to perform and there were only a few side effects.

Phantom limb imaginary fingertapping causes primary motor cortex activation: an fMRI study

A conventional 1.0 T MR-scanner was used to detect signal intensity changes in blood oxygenation level dependent-sensitive acquisitions of motor cortex during real (left hand) and imaginary (right hand) fingertapping in a man who had his right arm amputated. The subject was instructed alternately to move the intact left hand fingers and to imagine tapping his 'fingers' on the amputated right hand. Activated areas were detected using a cross-correlation technique with superimposition of highly correlated voxels on to a corresponding high resolution, anatomical 3D image. Activation was observed in the right motor cortex during fingertapping with the intact left hand, and a corresponding activation in the left motor cortex for imaginary movements of the amputated right hand fingers.

Upper airway symptoms and function in wood surface coating industry workers

Respiratory and ocular effects from exposure to airborne contaminants in workers employed in the manufacture of wood products using ultraviolet radiation curing (UV) or acid curing (AC) of surface coating were investigated. Surface coating line or finishing workers exclusively employed in one or both processes were compared to a control group. Symptoms of exposure were investigated by questionnaire and medical examination. Nasal, pharyngeal, and ocular symptoms of discomfort, but not lower airway, were common among all exposed groups. These symptoms were most frequent in UV line workers and finishers of UV surface-coated wood products. Mucociliary clearance was significantly slower in UV line workers. Significantly higher olfaction thresholds were observed in UV line and AC line workers and finishers of UV/AC surface-coated wood products. Low levels of organic solvents and coating dusts (composed in part of wood dust, chemical composition unknown) were measured in the workers' breathing zones. Although remarkable improvements have been made in both AC and UV surface coating, additional control measures to eliminate airborne contaminants and improved work practices are required.

Symptoms, airway physiology and histology of workers exposed to medium-density fiber board

Medium-density fiber (MDF) board was recently introduced in the furniture industry. In this pilot study health complaints, physiology, and histology of the upper airways were evaluated for two groups of workers, one handling MDF board for at least one-third of their work week (MDF group) and another handling traditional fiber board. Civil servants served as a reference group. The frequency of health complaints concerning the airways was higher, the sense of smell was poorer, and the frequency of nasal obstruction measured with rhinomanometry was higher for the MDF group, while mucociliary activity was lower in the group handling traditional board. In both groups forced vital capacity was low when compared with expected values. Histological specimens from the middle turbinate of the nose showed, in a few cases, nasal epithelial dysplasia in the traditional board group, but histological changes in terms of scoring did not differ significantly between the groups.

[Group therapy of patients with chronic pain]

51 patients suffering chronic pain, with different diagnoses, were treated in groups as outpatients using a cognitive behavioural approach. Groups of 7-8 patients met for two hours a week for six weeks. The groups were led by a team consisting of a clinical psychologist, a physiotherapist and a doctor. The patients learned about different aspects of pain, self-exercise and relaxation by selfhypnosis. Group dynamics was used to strengthen self-esteem, facilitate learning and encourage a change of attitude towards pain. Each patient answered a questionnaire about activities, level of pain, drugs and psychological symptoms before and immediately after treatment, and at follow-up one year later. At follow-up, 43% were less depressed, 70% felt less pain and 50% were more active and used less drugs.

Reduction of exposure to solvents and formaldehyde in surface-coating operations in the woodworking industry

A 1-year study has been performed at a company which manufacturers office furniture, and can be subdivided into three phases: measurement of exposure prior to remedial measures; remedial measures whose purpose was to reduce exposure; and new measurements after remedial measures. Remedial measures concentrated on changes which would reduce exposure to solvents. These measures fall into two categories: (i) the training of employees about the way airborne pollutants spread and ways of avoiding exposure; and (ii) locating and eliminating important sources of emission. Employees were trained mainly by the PIMEX (PIcture Mix EXposure) method for showing them how exposure depended on methods of work and conditions at the workplace. The most important sources of solvent emissions were pin-pointed by the GridMap method. The results show that exposure can be greatly reduced through training, adjustment of existing equipment and minor technical measures. This is the case even when exposure is initially at a concentration which is clearly below hygienic limit values. This approach should also reduce exposure to formaldehyde, though this could not be evaluated because the raw materials used changed during the study.

Histological changes in the nasal mucosa in persons occupationally exposed to formaldehyde alone and in combination with wood dust

In the nasal mucosa of rodents, both formaldehyde and wood dust have proved to be carcinogenic. Wood dust is also a well-known nasal carcinogen in man. The effects of long-term exposure of humans to formaldehyde, however, are more obscure. In this investigation two groups of workers with well-defined exposure to formaldehyde and to formaldehyde and wood dust, respectively, were compared with a control group regarding histological changes in nasal specimens from the middle turbinate. Significant changes were found in the formaldehyde group but not in the group exposed to both formaldehyde and wood dust. No correlation was found between histological changes and duration of exposure, doses of exposure or smoking habits.

Video filming and pollution measurement as a teaching aid in reducing exposure to airborne pollutants

A method called PIMEX has been developed for investigation of the causes of exposure to airborne pollutants at workplaces. The method involves measurement of the subject's exposure with a personal, direct-reading instrument. The sampling signal is transmitted by telemetry to a special video mixer. A video camera is also connected to the video mixer. The camera is used for filming the subject. The video mixer's output signal is fed to a monitor which continuously shows how the subject works and how exposure varies. The method has been used for producing two films on the causes of exposure to solvent and effective measures for reducing exposure: one deals with screen printing and the other with surface treatment at wood-processing plants. The films have been shown at a large number of workplaces at discussions about workplace conditions, proving useful tools in efforts to reduce workplace risks and giving rise to concrete measures and increased interest in the workplace environment.

Effects of exposure to vehicle exhaust on health

Exposure to combustion engine exhaust and its effect on crews of roll-on roll-off ships and car ferries and on bus garage staff were studied. The peak concentrations recorded for some of the substances studied were as follows: total particulates (diesel only) 1.0 mg/m3, benzene (diesel) 0.3 mg/m3, formaldehyde (gasoline and diesel) 0.8 mg/m3, and nitrogen dioxide (diesel) 1.2 mg/m3. The highest observed concentration of benzo(a)pyrene was 30 ng/m3 from gasoline and diesel exhaust. In an experimental study volunteers were exposed to diesel exhaust diluted with air to achieve a nitrogen dioxide concentration of 3.8 mg/m3. Pulmonary function was affected during a workday of occupational exposure to engine emissions, but it normalized after a few days with no exposure. The impairment of pulmonary function was judged to have no appreciable, adverse, short-term impact on individual work capacity. In the experimental exposure study, no effect on pulmonary function was observed. Analyses of urinary mutagenicity and thioether excretion showed no sign of exposure to genotoxic compounds among the occupationally exposed workers or among the subjects in the experimental study.

Concurrent video filming and measuring for visualization of exposure

A method has been developed for simultaneous video filming and exposure measurement with a presentation of the current exposure level mixed into the picture. With the aid of special equipment, the video camera and the instruments are coupled together in such a way that the outgoing video signal will give a picture carrying superimposed information as to the current level of the exposure. It is intended to serve as an aid in the evaluation of various measures for reducing the exposure and in connection with the training of personnel performing work involving exposure. The method has been tried out for air pollutants in seven different cases where exposure to organic solvents, carbon monoxide, wood dust and fume from welding occurred. The result, in the form of a film, showed with great clarity what working operations were critical with regard to the current exposure. In one plant where the method was used in connection with spray-painting, a study was undertaken in order to see how the exposure could be reduced by simple measures. The results showed that the exposure was reduced drastically. The method is usable for air pollutants and also for other measurable environmental factors. The method is ready for use, but there are many ways in which the system could be improved. Further evaluation is also necessary.

Lung function and rhizopus antibodies in wood trimmers. A cross-sectional and longitudinal study

Pulmonary function was studied in 66 wood trimmers exposed to organic dust (moulds) after a month of no exposure (summer vacation) and then three and 27 months later, and also during a working week. The results of forced expirometry and single breath nitrogen washout were compared with those obtained in local controls and in larger reference materials. The forced vital capacity (FVC) and forced expired volume in one second (FEV1) were reduced by an average of 0.4 and 0.31, respectively, after one month of no exposure, however, the nitrogen washout variables showed no clear changes. Repeated measurements three months later on a Monday morning after two days of no exposure showed a further reduction in FVC and FEV1 by an average of 0.21 in a sawmill with high exposure to moulds (10 colony-forming units/m3), but not in another sawmill with ten times lower exposure. Further recordings 27 months later (Monday morning before work) displayed no further worsening in any spirometric variable. No change in lung function was noted after one day of work (Monday morning to Monday evening), but a further reduction in FVC of an average of 0.31 was seen in non-smokers at the end of the week, with apparent resolution over the weekend. The impairment was more obvious at the sawmill with higher air concentrations of organic dust than at the other sawmill. It is concluded that wood trimmers may develop restrictive pulmonary dysfunction, which might be explained by an immunopathological reaction to heavy mould exposure.

Exposure to terpenes: effects on pulmonary function

Forty-eight subjects exposed to terpenes (mean air concentration 258 mg m-3) and 47 unexposed subjects, all employed at sawmills, were studied with regard to symptoms and pulmonary function. Dyspnoea and chest oppression were significantly increased in the exposed subjects compared to the unexposed controls. A reduced FEV1, on spirometry and an increased CV% and slope of the alveolar plateau (phase III) on single breath nitrogen washout were seen on Monday morning before exposure to terpenes. There was no correlation between exposure time (duration of employment) and lung function impairment. A day of industrial exposure to terpenes caused no further change in any lung function variable. The unexposed controls showed normal spirometry and nitrogen washouts. The findings indicate a slight stable lung function impairment of an obstructive nature which does not necessarily undergo further deterioration with increased duration of exposure.