Lee, Yuen Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 81-102). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / Table of contents --- p.vi / List of Figures --- p.ix / List of Abbreviations --- p.xi / Chapter Chapter 1. --- General introduction --- p.1 / Chapter Chapter 2. --- Literature review / Chapter 2.1 --- History of food allergy research --- p.3 / Chapter 2.2 --- Prevalence of food allergy --- p.4 / Chapter 2.3 --- Clinical symptoms of food allergy --- p.6 / Chapter 2.4 --- Mechanism of food allergy --- p.6 / Chapter 2.4.1 --- Properties of food allergens --- p.7 / Chapter 2.4.2 --- Exposures to food allergens in the gastrointestinal tract --- p.8 / Chapter 2.4.3 --- Oral tolerance and its relationship to food allergy --- p.9 / Chapter 2.4.4 --- Cellular mechanism of food allergy --- p.13 / Chapter 2.5 --- Studies on seafood allergies and allergens --- p.17 / Chapter 2.6 --- Use of animal models in the study of food allergy --- p.22 / Chapter 2.6.1 --- Selection of species and strain for developing animal models --- p.22 / Chapter 2.6.2 --- Parameters of sensitization protocol --- p.25 / Chapter 2.6.3 --- Lessons from animal models --- p.27 / Chapter 2.6.3.1 --- Investigations on pathogenesis of food allergy --- p.27 / Chapter 2.6.3.2 --- Studies on development of therapeutic strategies --- p.28 / Chapter Chapter 3. --- Characterization of hypersensitive responses to recombinant shrimp tropomyosin in mice / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Materials and Methods / Chapter 3.2.1 --- Preparation of the recombinant shrimp tropomyosin / Chapter 3.2.1.1 --- Expression of the recombinant shrimp tropomyosin --- p.32 / Chapter 3.2.1.2 --- Extraction and purification of the recombinant protein under native condition --- p.32 / Chapter 3.2.1.3 --- Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) --- p.33 / Chapter 3.2.1.4 --- Quantification of the recombinant protein and detection of level of endotoxin in the protein --- p.34 / Chapter 3.2.2 --- Characterization of hypersensitive responsesin mice / Chapter 3.2.2.1 --- Mice --- p.37 / Chapter 3.2.2.2 --- Sensitization and challenge of mice --- p.37 / Chapter 3.2.2.3 --- Assessment of systemic anaphylaxis responses --- p.38 / Chapter 3.2.2.4 --- Detection of shrimp tropomyosin specific IgE level --- p.39 / Chapter 3.2.2.5 --- Passive cutaneous anaphylaxis (PCA) test --- p.40 / Chapter 3.2.2.6 --- In vitro proliferation assay under stimulation of shrimp tropomyosin --- p.40 / Chapter 3.2.2.7 --- Cytokine profile of splenocytes --- p.42 / Chapter 3.2.2.8 --- Histological examination of small intestine --- p.44 / Chapter 3.2.2.9 --- Statistical analysis --- p.45 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Preparation of the recombinant shrimp tropomyosin --- p.47 / Chapter 3.3.2 --- Induction of systemic anaphylaxis responses after challenge --- p.48 / Chapter 3.3.3 --- Elevated level of shrimp tropomyosin specific IgE --- p.49 / Chapter 3.3.4 --- Passive cutaneous anaphylaxis (PCA) reactions --- p.50 / Chapter 3.3.5 --- Proliferation response of splenocytes under in vitro stimulation --- p.54 / Chapter 3.3.6 --- Cytokine profiles of restimulated splenocytes --- p.58 / Chapter 3.3.7 --- Histology of small intestine --- p.65 / Chapter 3.4 --- Discussion --- p.68 / Chapter Chapter 4. --- General conclusion --- p.78 / References --- p.81

O desenvolvimento da alergia pode ter início precoce, durante os primeiros meses de vida ou ainda durante a gestação. Em camundongos, é descrita uma predisposição ao desenvolvimento de resposta Th2 no período neonatal, contribuindo para o desenvolvimento da resposta alérgica. A maturação das funções relacionadas à resposta Th1 pelo uso de adjuvantes imunológicos no período pós-natal pode contribuir na profilaxia da asma e outras doenças alérgicas. Neste trabalho, investigamos o efeito dos oligodeoxinucleotídeos CpG na imunização com ovalbumina (OVA) e extrato do ácaro Blomia tropicalis (Bt) em camundongos nos períodos neonatal e adulto. Os resultados obtidos mostram que o ODN-CpG é capaz de diminuir a produção de anticorpos IgE, um isótipo dependente de citocinas Th2, e aumentar os níveis de anticorpos IgG2a nas imunização com OVA e Bt, inclusive na imunização com os dois alérgenos associados. Além disso, a associação do ODN-CpG na imunização neonatal com OVA promove um aumento da produção in vitro de IFN-<font face=\"symbol\">g e diminuiu a produção de IL-10. Ao compararmos a eficiência modulatória do CpG nas imunizações com OVA em camundongos adultos e neonatos, observamos um maior efeito modulatório na produção de anticorpos em adultos. Os resultados mostraram que linfócitos B de camundongos jovens não aumentam a expressão do TLR-9 mesmo após 72 horas de estímulo com CpG, enquanto nos linfócitos de adultos já é possível observar um aumento em 48 horas. Além da menor ativação dos linfócitos B, evidenciamos uma produção de IL-10 e MCP-1 significantemente aumentada na cultura de células de neonatos após estímulo in vitro com CpG. Ao avaliarmos a influência do CpG na ativação antígeno específica dos linfócitos T CD4+, mostramos que linfócitos T CD4+ de neonatos expressam mais intensamente moléculas B7 do que células de adultos após estímulo antigênico in vitro, o que sugere uma característica supressora nestas células. Esse aumento foi inibido pela adição de CpG na cultura. A indução de células Treg (CD4+CD25+Foxp3+) in vitro também foi suprimida pela adição de CpG. Nossos resultados mostram um potencial modulatório do CpG no período neonatal e adulto nas respostas a OVA e Bt. Evidenciamos, também, diferenças qualitativas e quantitativas no efeito do CpG em relação às imunizações neonatal e adulta. Considerando a suscetibilidade dos neonatos às infecções e ao desenvolvimento de alergia, torna-se importante estabelecer estratégias imunomodulatórias que potencializem as respostas inata e adaptativa e possam ser profiláticas no desenvolvimento de doenças alérgicas. / The allergy development may occur in the early life, during the pregnancy or postnatally at the first months of life. In mice, it is described a predisposition to Th2 biased response in the neonatal period, favoring the development of allergic response. The maturation of functions related to Th1 response by the use of immune adjuvants may be beneficial to the allergy prophylaxis. In this work, we evaluated the effect of CpGcontaining oligodeoxynucleotides (CpG-ODN) in the neonatal and adult immunization with ovalbumin (OVA) or the extract of house dust mite Blomia tropicalis (Bt). The results show CpG-ODN is able to decrease IgE antibody production, an isotype related to Th2 response, and increase IgG2a antibody levels in OVA or Bt immunization of A/Sn mice, even when mice were co-immunized with both allergens. Moreover, CpG-ODN association in neonate immunization with OVA increases in vitro IFN-<font face=\"symbol\">g production and decreases IL-10. Comparing the modulatory efficiency of CpG in OVA immunization of neonate and adult mice, we observed a stronger effect on antibody production in adults. Results show that B cells from young mice do not increase the TLR-9 expression upon CpG stimulation for 72 hours whereas the increase of TLR-9 in adult B cells occurs within 48 hours. Besides the lower B cell activation, we found a significant increase of IL-10 and MCP-1 secretion levels by the neonatal cells stimulated by CpG. When we evaluated the influence of CpG on CD4+ T cell activation upon antigenic stimulation, we verified an upregulation of B7 molecules expression on neonate cells than adult cells. This high expression was inhibited by the addition of CpG in the culture. The induction of regulatory T cells (CD4+CD25+Foxp3+) in vitro was also suppressed by CpG. Our results show a modulatory potential of CpG in the immune response to OVA and Bt in both neonatal and adult periods. We also evidenced qualitative and quantitative differences in the CpG effect between neonates and adults. Considering the susceptibility to infections and allergy development in newborns, it becomes important to establish immunomodulatory strategies that enhance innate and adaptive responses and are prophylactic to the development of allergic disorders.

O Teste de Provocação Oral Duplo Cego Placebo Controlado (TPODCPC) é considerado um método diagnóstico de extrema importância na alergia alimentar, entretanto não existe, em nosso meio, uma padronização em relação aos materiais e métodos para a sua execução, especialmente na faixa etária pediátrica. O objetivo deste estudo foi adaptar TPODCPC para o diagnóstico de alergia às proteínas do leite de vaca (APLV) mediada por IgE, em crianças e adolescentes. O objetivo secundário foi descrever a relação entre os antecedentes de atopia associados a dados laboratoriais e os resultados dos TPODCPC. Foram incluídos 58 pacientes que se dividiram em dois grupos. O grupo 1 foi composto por 39 pacientes (mediana de idade: 5,3 anos; 1,6M:1F) com história sugestiva de APLV IgE mediada, sem relato de história de anafilaxia recente e com pesquisa positiva de IgE específica para leite de vaca (LV) e/ou frações. No grupo 2 foram incluídos 19 pacientes (mediana de idade: 8,3 anos; 1,4 M:1F) sem história sugestiva de APLV. Os itens avaliados na adaptação deste método diagnóstico incluíram: escolha do local, materiais a serem utilizados e operacionalização do teste. O hospital dia mostrou-se, por suas características, adequado à realização do exame. Em relação aos materiais escolhidos para a oferta do veículo, os recipientes opacos e vedados revelaram-se mais adaptados às necessidades do teste, os veículos de maior aceitação foram sopa de legumes e bebida à base de soja e o LV a ser oferecido de maneira mais apropriada foi na forma líquida e com baixo teor de lactose. As dificuldades observadas na realização do TPODCPC não comprometeram a sua execução, entretanto houve dificuldade na interpretação dos resultados especialmente nos pacientes com sintomas como pápulas periorais ou achados clínicos inespecíficos. Observou-se concordância entre os critérios clínico-laboratoriais adotados para a definição dos grupos 1 e 2 com os resultados do TPODCPC. Em conclusão, o teste mostrou-se exeqüível e seguro e a adaptação deste para o diagnóstico de APLV IgE mediada nesta faixa etária pediátrica foi possível, sendo necessária a avaliação da sua reprodutibilidade em outras populações. / The Double Blind Placebo Controlled Food Challenge (DBPCFC) is considered an important method for food allergy diagnosis, nevertheless it is not standardized among us. The aim of this study was to adapt DBPCFC for cows milk allergy (CMA) diagnosis in children and adolescents. A secondary aim was to describe the relation between history of atopy and laboratorial findings with DBPCFC results. It was included 58 patients that were distributed in two groups. Group 1 was composed of 39 patients (median age: 5,3 years; 1,6M:1F) with suggestive history of CMA without recent anaphylaxis, and specific IgE to cow´s milk (CM) and/or its fractions. In group 2 was included 19 patients (median age 8,3 years; 1,4 M:1F) where the CMA diagnosis was excluded based on clinical findings. The items evaluated in the adaptation of this method were: setting choice, kind of milk processing and vehicles, besides material and test performance. Day hospital was considered adequate for this test. Regarding to elected materials to offer the vehicle, opaque and sealed recipients showed more suitable to test demands. Vehicles more accepted were legumes soup and soy beverage and the most adequate CM to be offered was liquid and with low lactose concentration. The difficult observed in performance of DBPCFC do not compromise its execution, however the interpretation of the results was very difficult specially in patients with perioral wheals and unspecific clinical findings. There is an agreement Comparing adopted clinical and laboratorial criterion for definition of group 1 and 2 with DBPCFC results. In conclusion, the test proved to be feasible and safe and its adaptation is possible for IgE mediated CMA diagnosis, being necessary to evaluate its reproducibility in other populations.

Purpose: Cetuximab is a monoclonal antibody with a known risk of hypersensitivity reactions. Early studies showed hypersensitivity reaction rates of 3%, but there appears to be a higher incidence in the southeastern United States. To confirm the findings from nearby institutions that cetuximab-associated hypersensitivity reactions occur in approximately 20% of patients in the southeastern United States. Methods: A retrospective chart review was conducted at Johnson City Medical Center in Johnson City, Tennessee. Each patient’s first infusion was analyzed for hypersensitivity reaction, as well as for demographic information such as allergy and smoking history, pre-medications, and malignancy type. Results: Data from the first infusion of cetuximab were collected for a total of 71 patients with various malignancies. The overall rate of grade 3 or higher hypersensitivity reaction was 1.4%, and total rate of hypersensitivity reaction was 8.5%. These findings more closely correlate to the early clinical trials and package insert. Both severe (p = 0.001) and any-grade (p = 0.002) hypersensitivity reaction occurred less frequently in one Southeastern Appalachian medical center compared to academic medical centers directly to the east and west. Conclusions: Patients in southern Appalachia may be less likely to develop cetuximab hypersensitivity reactions compared to surrounding areas in the Southeastern U.S. These results lend support to the theory that exposure to lonestar ticks (Amblyomma americanum) may be responsible for the development of IgE antibodies to cetuximab that cause hypersensitivity reactions. The development of quick and reliable bedside predictors of cetuximab hypersensitivity reactions may aid clinicians considering the use of cetuximab.

Purpose: Neuromuscular blocking agents are a common cause of hypersensitivity reactions during surgery. An allergy evaluation, including skin testing of these drugs prior to future surgeries, may help prevent life threatening reactions. Drug concentrations utilized for skin testing vary by country and institution. The purpose of this study was to investigate the stored stability of clinically relevant dilutions of neuromuscular blocking agents (NMBAs), namely succinylcholine, atracurium, cisatracurium, rocuronium, pancuronium, and vecuronium, for skin prick/intradermal testing. Methods: Concentrations of NMBAs were monitored by liquid chromatography-mass spectrometry (LC-MS/MS) for a period of 14 days. Dilutions of NMBAs were prepared in saline by factors of 10x, 100x, 1,000x, 10,000x, and 100,000x, as sensitivity of the assay allowed. Diluted drug products were stored in a laboratory refrigerator until sampling. On sampling days, aliquots of each dilution were removed for analysis, and compared to a freshly prepared set of reference dilutions. Results: Acceptable potency of the stored preparations is defined as 90-110% of the initial drug concentration (versus a reference). All drugs were stable for at least 48 hours in the 1:10 dilution and for 24 hours in the 1:100 dilution. At higher dilution factors, the detectable amount of drug in the stored dilutions deteriorated rapidly, indicating that such preparations should be used immediately. Conclusion: With increasing dilution factors, the stability of these drugs in saline decreases, increasing deviation between samples and references. The most stable dilutions for each of the drugs tested were 10x and 100x.

Fibromyalgia (FM) is a musculoskeletal and neurological disorder that causes constant pain, cognitive problems with short term memory, and sleep disorders. There are more females diagnosed with FM than males, and research has therefore primarily been conducted with females. Because little is known about African American males with FM, biopsychosocial theory was used in this phenomenological study to examine how African American males with FM are affected biologically, psychologically, and socially. Eight African American males diagnosed with FM were recruited from Houston, Texas and were interviewed about their lived experiences with FM, including experiences with the healthcare system, and how they used the internet to seek information about FM. Individual interview transcripts, conduct open coding, and thematic analysis led to identification of the following themes: (a) lengthy multiple medical evaluations to receive a diagnosis and various symptoms; (b) physical challenges, physical limitations, emotional issues, and cognitive issues experienced with FM; (c) limited physical and emotional support from family and friends; (d) hopeful about work and plans; (e) trust and confidence in healthcare providers and medical information obtained by asking questions; (f) limited internet search and not involved in online FM forums. The study showed that African American males with FM may experience debilitating symptoms and may use faith-based beliefs as one way to cope with FM. These results may bring positive social changes by providing caretakers with a better understanding of how FM affects the quality of life of African American males with FM, and provide new data to assist healthcare providers in diagnosing, treating, and serving this population.

Les douleurs abdominales, principale cause de consultation en gastroentérologie, sont souvent le reflet d’un dysfonctionnement du tractus gastro‐intestinal, parfois responsable d’un Syndrome de l’Intestin Irritable (SII) ou d’une Maladie Inflammatoire Chronique de l’Intestin (MICI). Ces deux types de pathologies ont des caractéristiques bien distinctes (inflammation sévère avec des phases de poussée et de rémission dans le cas des MICI, absentes dans le SII). Cependant elles ont aussi des caractéristiques communes comme le développement d’une hypersensibilité colique (HSC), visible pendant les phases de rémission des MICI. Cette hypersensibilité, dont la physiopathologie est encore mal connue, entraîne une altération de la qualité de vie des patients. Il paraît donc nécessaire de comprendre les mécanismes qui sous‐tendent son apparition, son développement et son maintien, afin de développer des stratégies thérapeutiques adaptées. Les canaux ioniques sont des cibles intéressantes pour cela. Deux ont particulièrement retenu notre attention : le canal ASIC3 (Acid Sensing Ion Channels), sensible à l’acidose tissulaire et impliqué dans de nombreux processus physiopathologiques douloureux et le canal calcique Cav3.2 (voltage‐gated calcium channel) impliqué dans la mécanoperception physiologique et physiopathologique. Dans une première partie, nous avons évalué le rôle des sous‐unités ASIC3 dans l’hypersensibilité colique. Pour cela, nous avons utilisé plusieurs modèles animaux mimant une hypersensibilité colique de diverses origines chez des animaux déficients pour le canal ASIC3 et leurs littermates. Le premier modèle utilisait du DSS à deux concentrations : 0.5% et 1% induisant une hypersensibilité colique respectivement sans et avec inflammation. Le deuxième modèle mimait une hypersensibilité colique induite par une infection gastro‐intestinale. Pour cela, nous avons utilisé une bactérie AIEC (Adherent Invasive Escerichia Coli) de souche LF82 anormalement présente chez les patients atteints de la maladie de Crohn. Nous avons mis en évidence que le canal ASIC3 est impliqué dans la mise en place de l’Hypersensibilité Viscérale d’origine Colique (HSVC) dans ces deux modèles, et que la délétion de cette sous‐unité entraîne une moindre inflammation colique. Dans un dernier modèle, pour déterminer si ces résultats au niveau colique étaient transposables au cas d’une hypersensibilté viscérale d’origine différente, nous avons choisi un modèle de cystite pour lequel nous n’avons pas pu mettre en évidence une implication de la sous‐unité ASIC3. Dans une deuxième partie, nous avons travaillé sur le canal calcique Cav3.2, déjà étudié au laboratoire, et qui n’avait pas montré d’implication dans les douleurs viscérales inflammatoires. Son implication dans l’HSC non inflammatoire a été étudiée à travers deux modèles : le modèle de DSS 0.5% et le modèle de séparation maternelle. Une absence d’hypersensibilité chez les animaux déficients pour ce canal a été mise en évidence, et nous avons trouvé une implication de ce canal calcique chez des patients atteints du SII. La dernière partie de ce travail s’est intéressée à une nouvelle cible pouvant être impliquée dans la perception des stimuli mécaniques au niveau colique, le facteur de transcription EGR‐4. Ce facteur de transcription appartient à la famille des protéines en doigts de zinc et est extrêmement conservé entre les êtres vivants ; il est impliqué dans de nombreuses cascades de signalisations cellulaires. Une équipe clermontoise a montré son implication dans la mécanoperception chez la plante. Nous avons donc voulu savoir si cette implication était transposable à la souris et nos travaux se sont alors concentrés sur le côlon et sur l’implication de ce facteur lors d’une stimulation mécanique. Il est principalement exprimé au niveau des cellules musculaires lisses et est surexprimé au niveau du côlon dans le cas d’une stimulation mécanique. / Abdominal pain is one of the most common gastrointestinal disorder which accounts for the majority ofconsultations in general practice and half of those in gastroenterology. They often reflect a dysfunction ofthe gastrointestinal tract may be responsible for irritable bowel syndrome (IBS) or chronic inflammatorybowel disease (IBD). Despite significant differences particularly illustrated by a severe inflammatoryphenomenon associated with IBD which is not observed in IBS, these pathologies share colonichypersensitivity (CHS) as a common feature. This hypersensitivity whose pathophysiology is still poorlyunderstood, results in impaired quality of life of patients. It therefore seems necessary to be able tounderstand the mechanisms that underlie the emergence, development and maintenance of the HSC todevelop appropriate therapeutic strategies. Ion channels are attractive targets because of their critical role insynaptic transmission of sensory information. Two of them in particular caught our attention: ASIC3 channel(Acid Sensing Ion Channels), sensitive to tissue acidosis and involved in many pathophysiological processesand painful calcium channel Cav3.2 (voltage‐gated calcium channel) involved in the physiologic andpathophysiologic mechanoperception.In the first part, we evaluated the role of ASIC3 subnits in colonic hypersensitivity. For this, we used severalanimal models mimicking colonic hypersensitivity of different origins in deficient animals for ASIC3 and theirlittermates. The first model using the DSS at two concentrations: 0.5% and 1% respectively inducing colonichypersensitivity with and without inflammation. The second model mimicking colonic hypersensitivityinduced gastrointestinal infection. For this, we used a AIEC bacteria (Adherent‐Invasive Escerichia Coli) ofLF82 strain abnormally present in patients with Crohn's disease. We were able to show that the ASIC3channel is involved in the establishment of the original Visceral Hypersensitivity Colic (HSVC) found in thesetwo models. We were also able to show that the deletion of this channel leads to lower colonic inflammationin our animals. Then, we evaluated its involvement in a cystitis model and found that this channel was notinvolved in this type of pain or in the resulting inflammation.In the second part, we worked on the calcium channel Cav3.2. This channel already studied in the laboratoryhad shown no involvement in visceral inflammatory pain, we observed his involvement in thenoninflammatory colonic hypersensitivity through two models: the DSS model 0.5% and the maternalseparation model. We were able to demonstrate a lack of hypersensitivity in animals deficient for thischannel. In addition, we found an involvement of this calcium channel in patients IBS, resulting in increasedexpression in these patients compared to control patients.The aim of this third part is to determine the EGR‐4 localization and its involvement in the mouse colonsensitivity to a mechanical stimulus. For that purpose, wild‐type and healthy mice were subjected or not to acolorectal distension (mechanical stimulus) for 10 seconds via inflation of a balloon inserted at 1cm from theanal margin. Then, we analyzed the expression of EGR‐4 at different time points after the distension at themRNA level in the colon, dorsal root ganglia (DRG) and spinal cord by quantitative RT‐PCR and its cellularlocalization in DRG, and in colon after whole‐mount dissection, by immunohistochemistry. We also identified targeted genes of this transcription factor in mouse colonic epithelial cells transfected by an EGR‐4expressing vector after microarray analysis. EGR‐4 transcription factor is localized in the colon, DRG andspinal cord cells. In addition, its expression is modified after colorectal distension in a time dependentmanner.

This thesis aims to increase the knowledge on people with symptoms attributed to electromagnetic fields (EMF) by investigating the effects of EMF exposure and by additional description of the heterogeneous group of people reporting EMF-related symptoms. The effect of mobile phone (MP)-like radio frequency (RF) fields on symptoms, autonomic nervous system (ANS) parameters, short-term memory, and reaction time in persons with MP-related symptoms (MP participants) was investigated in a provocation study. A second provocation study investigated the effect of similar exposure on serum concentration of biomarkers in persons with atopic dermatitis. No effect of exposure was detected in either study. MP participants displayed changes in heart rate variability (HRV) during cognitive tests, but not during rest. This contrasts with earlier findings, participants with symptoms attributed to EMF sources in general (EHS participants) displayed an elevated sympathetic nervous system activity both during cognitive tests and during rest. Proposed differences between subgroups of persons with EMF-related symptoms with respect to symptoms, personality traits and stress were investigated in a questionnaire study. MP participants reported primarily symptoms from the head; EHS participants reported symptoms from many organ systems. Furthermore, EHS participants reported higher levels of anxiety, depression, stress, and exhaustion when compared with a reference group. MP participants reported higher levels of anxiety and exhaustion only. In a pilot study, 24-hour and short-term HRV were investigated in EHS participants, to examine whether the previously observed sympathovagal imbalance would still be present. There was a tendency toward increased parasympathetic activity compared with earlier recordings, and a reduction of symptoms. Twenty-four hour and short-term recordings were fairly similar for each participant; however, there were large between-subject differences. The results do not support the hypothesis of effects of MP-like RF exposure on symptoms, ANS activity, CFFT, cognitive function, or biomarkers. However, they do support the hypothesis that persons with different symptom attribution (MP and EHS) may differ also in ANS activity and psychological aspects.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2010. / Härtill 4 uppsatser.

The overall aim of this thesis is to increase our knowledge of the physical environment of office workers with special focus on electromagnetic fields and to address the question of whether electromagnetic fields can directly or indirectly contribute to symptoms or discomfort among video display terminal ( VDT) workers. Furthermore, we have measured light modulation from various commonly used light sources in laboratory conditions and, as a second step, used modulated light as stimulus for provocation of neurophysiological responses in persons with perceived “electrical hypersensitivity” (EHS).During the last 20 years work-related illness among office workers has received increased attention. Changes in the physical environment, the introduction of VDTs and other electrical equipment and changes in light conditions have been discussed in this context. The basis for this thesis is the interdisciplinary Office Illness Project in Northern Sweden. Using a questionnaire completed by 4,943 office workers, 150 VDT workers with or without facial skin symptoms were selected for a case referent study of the electromagnetic fields in offices.When the measurements in the offices were performed in 1989, the general level of the 50 Hz magnetic fields in the offices was rather low, but in 5% of the offices the flux density exceeded 0.5 pT. At this level VDT monitors were shown to display detectable instability (jitter). Furthermore, the ability of test subjects (healthy volunteers) to detect jitter was shown to depend on both the amplitude and frequency characteristics of this instability. The study indicates that the instability of computer monitors and thereby the instability of the visual image of the VDT screen might be an increasing problem since it is known that the harmonic content of the general magnetic field in offices is on the rise.VDT monitors contributed to the magnetic field level at VDT workplaces in both extremely low and very low frequency ranges. However, the dominant source of electric fields in rooms was ungrounded electrical equipment, not VDT screens.High electric fields in the extremely low frequency range in the offices were associated with skin symptoms among VDT workers. The causal nature of this association cannot be determined since it may depend on undetected factors related to exposure. No associations were found, however, for any of the VDT-related electromagnetic fields and skin symptoms.Commonly used fluorescent tubes in our office environment have a degree of modulation of the light (flicker) that varies widely from less than 1% (fluorescent tubes with high frequency gear) up to nearly 100%. When persons with perceived EHS were exposed to flickering light, a higher amplitude of brain cortex responses were found at all tested frequencies compared with control subjects. These findings are of considerable interest, but further studies are required in order to establish a possible relationship between flickering light and discomfort/symptoms in persons with perceived EHS. / digitalisering@umu