| 1. |
- Ahmed, Fozia
(författare)
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Estrogen and its receptors in adipose tissue from women and men : Associations with age, adiposity and type 2 diabetes
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Obesity and its complications, such as insulin resistance and type 2 diabetes (T2D), are leading causes of morbidity and mortality globally. Adipose tissue is important for whole-body homeostasis, functioning as an energy storage reservoir and an endocrine organ. Estrogens mediate their effects through estrogen receptor alpha (ESR1) and beta (ESR2) and contribute to sex and menopause-related differences in body fat distribution. Moreover, estrogens can be produced from androgens in the adipose tissue by the enzyme aromatase. The overall aim of this thesis was to investigate the role of estrogen and estrogen signalling in human adipose tissue and their association with age, adiposity, and insulin resistance. In Paper I, we assessed ESR1 and ESR2 gene expression in subcutaneous adipose tissue (SAT) from pre- and postmenopausal women, and investigated the effects of estradiol on adipocyte glucose uptake. We found that ESR2 gene expression was higher in postmenopausal women than premenopausal women. Moreover, in late, but not pre- or early postmenopausal women, estradiol incubation reduced basal and insulin-stimulated glucose uptake, which corresponded to an increase in ESR2 gene expression levels. The inhibiting effect of estradiol on adipocyte glucose uptake was prevented using an ESR2 antagonist. Subsequently, in Paper II we assessed the role of ESR2 in SAT lipid and glucose metabolism and preadipocyte differentiation. ESR2 expression in SAT was inversely correlated with markers of central adiposity and positively correlated with markers of lipid accumulation. Moreover, ESR2 knockdown impaired subcutaneous preadipocyte differentiation and glucose utilization. In Paper III, we focused on adipocyte lipolysis in women, which is regulated, in part, by catecholamines. OCT3, which mediates catecholamine transport into adipocytes, where they can be degraded, was increased in SAT with age, and higher in postmenopausal women than premenopausal women. Moreover, its expression was negatively associated with markers of insulin resistance and ex vivo lipolysis. Estradiol incubation of SAT downregulated OCT3 gene expression, which may explain lower OCT3 gene expression in premenopausal compared to postmenopausal women. In Paper IV, we focused on the role of aromatase and estradiol in SAT from men. We found that aromatase expression was higher in SAT from men with obesity and T2D compared to subjects without obesity and T2D, respectively, and was positively associated with markers of central obesity and markers of insulin resistance. Contrastingly, ESR1 expression in SAT was lower in men with obesity and T2D compared to subjects without obesity and T2D, respectively, and negatively associated with markers of obesity and insulin resistance. ESR2 expression was higher in SAT from men with T2D compared to men without T2D. Estradiol reduced insulin-stimulated glucose uptake, however, neither testosterone, nor aromatase inhibition, altered adipocyte glucose uptake. In this thesis, we found that estrogen has important metabolic effects in adipose tissue, including regulating lipid accumulation, glucose uptake capacity, and catecholamine transport. Overall, our findings suggest that estrogen and estrogen receptors may have an important role in age-, menopausal- and sex-dependent differences in body fat distribution, and may serve as potential targets for the prevention and treatment obesity and insulin resistance.
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| 2. |
- Andrén, Lina J., 1980-
(författare)
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On Latin squares and avoidable arrays
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of the four papers listed below and a survey of the research area. I Lina J. Andrén: Avoiding (m, m, m)-arrays of order n = 2k II Lina J. Andrén: Avoidability of random arrays III Lina J. Andr´en: Avoidability by Latin squares of arrays with even order IV Lina J. Andrén, Carl Johan Casselgren and Lars-Daniel Öhman: Avoiding arrays of odd order by Latin squares Papers I, III and IV are all concerned with a conjecture by Häggkvist saying that there is a constant c such that for any positive integer n, if m ≤ cn, then for every n × n array A of subsets of {1, . . . , n} such that no cell contains a set of size greater than m, and none of the elements 1, . . . , n belongs to more than m of the sets in any row or any column of A, there is a Latin square L on the symbols 1, . . . , n such that there is no cell in L that contains a symbol that belongs to the set in the corresponding cell of A. Such a Latin square is said to avoid A. In Paper I, the conjecture is proved in the special case of order n = 2k . Paper III improves on the techniques of Paper I, expanding the proof to cover all arrays of even order. Finally, in Paper IV, similar methods are used together with a recoloring theorem to prove the conjecture for all orders. Paper II considers another aspect of the problem by asking to what extent way a deterministic result concerning the existence of Latin squares that avoid certain arrays can be used when the sets in the array are assigned randomly.
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| 3. |
- Ejdesjö, Andreas, 1978-
(författare)
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Teratogenic Predisposition in Diabetic Rat Pregnancy
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pre-gestational diabetes increases the risk of congenital malformation in the offspring and both morbidity and mortality in the diabetic mother and her offspring. During pregnancy, high glucose levels act as a teratogen through several cellular and biochemical pathways and increased production of reactive oxygen species (ROS) has a central role in diabetic embryopathy. The aim of this work was to investigate the importance of genetic predisposition for congenital malformations and to study the genes involved in the teratogenic process of diabetic pregnancy.The crossbreeding of two rat strains, with both low and high incidence of diabetes-induced malformations, indicated that strain-specific maternal factors, such as disturbed serum levels of amino acids, triglycerides, and β-hydroxybutyrate, were associated with malformation. In addition, disturbed fetal expression of genes involved in ROS defense and development (Shh, Bmp4, Ret and Gdnf) in mandible and heart, and decreased activity of Gapdh and Aldose Reductase were associated with the teratogenic process, and the trans-generational heredity of the mother determined the type of malformations induced by maternal diabetes.In rat embryos, a diabetic environment in utero changed the expression of genes involved in ROS defense (Nrf2, Gpx1 and Cat), development of mandible and heart (Msx2, Shh, Bmp4, Ret and Gdnf), and neural tube closure and apoptosis (Pax3 and p53). The changes were divergent with tissue-specific alterations of gene expression in developing mandible, heart anlage, and whole embryo.Disruption of the Receptor for Advanced Glycation End products (RAGE) had a protective effect against diabetic embryopathy in mice, and the blockage of RAGE diminished ROS production in the offspring: this supported oxidative stress being a necessary etiological component in diabetic embryopathy.Maternal metabolic state and genetic susceptibility influence fetal outcome in experimental diabetic pregnancy. Disturbed protection against oxidative stress and tissue-specific derangements in the expression of developmental genes play pivotal roles in the teratogenic mechanism, and enhanced levels of Advanced Glycation End products (AGE) and RAGE-induced oxidative stress are involved in diabetic dysmorphogenesis.
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| 4. |
- Eriksson, Ann-Kristin Mimmi
(författare)
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Vid utmattningens gräns. Utmattningssyndrom som existentiellt tillstånd : Vårdtagares och vårdgivares erfarenheter av utmattningssyndrom och rehabilitering med en existentiell ansats i svensk vårdkontext
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and objectives: Stress-related illness is a growing public health problem in Sweden and it is the most common reason for sick leave today. Stress-related illness causes suffering on a number of levels and affects the patient’s health and life in the long term. The stress-related ill health also leads to consequences for society, causing high costs for sick leave and health care as well as lost workforce since people partially or entirely lose their capacity to work. Research on stress-related ill health and rehabilitation often underline work-related conditions as crucial in dealing with the problem. There is also research that points out psychosocial factors in understanding stress-related ill health. What we know little about is the existential perspective of clinical burn-out. Therefore, it is of importance to investigate people’s existential experiences of clinical burn-out and the significance of an existential perspective in rehabilitation.Aim: The overall aim of this thesis is to gain insight into the existential experience of clinical burn-out as well as to highlight the significance of an existential perspective in rehabilitation. In addition, the thesis aims to reach a deeper understanding of clinical burn-out from an existential point of view and contribute to the field with knowledge of the existential dimension of health.Methods: The study, conducted in 2011, is based on qualitative interviews made with an inductive hermeneutic approach. Five patients and seven care givers were interviewed, focusing their existential experiences of clinical burn-out as well as their experiences of rehabilitation with an existential approach. A strategic selection was made of informants in the context of a rehabilitation program with an existential approach for people diagnosed with clinical burn-out. The data was analysed in two steps. In the first step the data was interpreted with an inductive hermeneutic approach. In step two of the analysis, the data was interpreted with a deductive hermeneutic approach, using Karl Jasper’s concept of limit situation as a way of interpreting the existential experience. Aaron Antonovsky’s concept sense of coherence was used as a tool for understanding components that can contribute to restoring health.Results: In this study, the patients describe clinical burn-out as a comprehensive existential experience that can be perceived as being in between life and death, in a shadow world, trapped in a dead end. It’s a situation characterized by being powerless. It creates a need to comprehend one’s situation in order to be able to regain control and manage it. It’s a struggle to make sense of the life situation. When not being met with understanding, the patients lose hope. Existential issues in terms of meaning, existence and life choices become urgent. Working with the existential perspective requires trust, openness from both caregiver and patient, distinctness, a way to communicate it and courage to take on the challenge of dealing with existential issues. The perspective also requires that the existential suffering can be contained. Dealing with existential questions leads to self-knowledge and insights that enables a possibility to make different choices and leave negative behavioural patterns. Also, it can lead to a discovery of spirituality and religion as a resource in life. Besides their personal struggle for meaning, the patients see an existential void in society, leaving people without tools to handle existential needs. This is understood as something that affects people’s ability to handle stressful times in life.The care providers understand burn-out as a manifestation of a way of living that is not sustainable. It is an existential experience embodied in body and mind that can be experienced as being drained of life. It’s an existential challenge, causing grief when realizing one’s limitations as a human being. Also, loss of meaning and sense of existential vulnerability due to an experience of being annihilated is crucial for understanding the deep existential crisis that clinical burn-out can induce. This situation makes the patient ask existential questions about identity, meaning, values and direction. In the burnout-process the patients have distanced themselves from their own self and therefore need to reconnect with themselves. This makes the existential questions central in the rehabilitation as a way to reconnect to inner strength and resources, which are prerequisites for starting a health promoting, sustainable process which is empowering, making it possible to see oneself as a human being who experience meaning, not only as a patient with a diagnosis. Instead of finding meaning in the diagnosis, the patient’s existential questions and the existential experience is a key to moving forward, out of the situation. Meaning-making is therefore important in the rehabilitation.A holistic-existential approach and view of man makes it possible to work with the complexity of the situation. The holistic-existential approach creates synergies and offers an extra tool both for the caregiver and the patient. Focusing on the patient’s resources and competence makes it possible to see the crisis as a way to learn from it.The existential perspective in health care and rehabilitation is enabled by competence, openness, reliance, empathy and respect when meeting the patient. It also requires courage to take on the challenge of dealing with existential issues. It can be hard for both the patient and the care giver to confront existential suffering. It is the responsibility of the care giver to enable the existential perspective by acknowledging and making the existential perspective possible to communicate and work it through.The care providers understands values in modern society as contributing to people’s experience of feeling alone with existential needs, which intensifies their existential aloneness.The care providers’ experience is that the biomedical paradigm aggravates an existential perspective. The perspective is not associated with the care situation. There is a lack of knowledge about and understanding of the value of the existential perspective, all the way from the decision-making level to the clinical meeting with the patient. In addition, the paradigm affects how the patients express their illness. Also, the perspective requires time. Existential perspectives, therefore, tend to be concealed in the health care context.Applying Karl Jasper’s concept of limit situation, clinical burn-out can be interpreted as a defining existential experience. It can be understood as a limit situation when humans realize their limitations and at the same time get insights that are crucial for their lives. It’s an experience they wish they had not gone through, but on the other hand, it has led to insights they do not want to be without. The meaning-making process is health promoting by recreating meaning, the fundamental part of sense of coherence, which is crucial for a salutogenic direction.Conclusion: The existential state that the clinical burnout patients go through can, using Karl Jasper’s concept, be understood as a limit situation. According to Jasper’s reasoning, the limit situation can be perceived as facing an abyss, making it clear one has limitations as a human being. At the same time, the experience can be perceived as reaching a limit where humans can get insights about human life that can enhance life. Clinical burn-out, using Aaron Antonovsky’s concept, can be understood as a loss of the components that create sense of coherence. Loss of meaning is particularly central for understanding burn-out.Consequently, it is crucial to acknowledge the existential challenge that the patient is facing, as well as the importance of the meaning-making process for facilitating a movement in a health promoting manner. It gives a deeper understanding of the challenges and needs of patients suffering from clinical burn-out.The existential dimension of health has been highlighted in health promotion, but gets little attention in practice. This is especially significant in the health care context. This points out the need for a discussion about how the existential health dimension can be used as a resource in health care and rehabilitation and how this resource for health can be applied in a better way in health promotion and public health.
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| 5. |
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| 6. |
- Eriksson, Erik J., 1978-
(författare)
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That voice sounds familiar : factors in speaker recognition
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Humans have the ability to recognize other humans by voice alone. This is important both socially and for the robustness of speech perception. This Thesis contains a set of eight studies that investigates how different factors impact on speaker recognition and how these factors can help explain how listeners perceive and evaluate speaker identity. The first study is a review paper overviewing emotion decoding and encoding research. The second study compares the relative importance of the emotional tone in the voice and the emotional content of the message. A mismatch between these was shown to impact upon decoding speed. The third study investigates the factor dialect in speaker recognition and shows, using a bidialectal speaker as the target voice to control all other variables, that the dominance of dialect cannot be overcome. The fourth paper investigates if imitated stage dialects are as perceptually dominant as natural dialects. It was found that a professional actor could disguise his voice successfully by imitating a dialect, yet that a listener's proficiency in a language or accent can reduce susceptibility to a dialect imitation. Papers five to seven focus on automatic techniques for speaker separation. Paper five shows that a method developed for Australian English diphthongs produced comparable results with a Swedish glide + vowel transition. The sixth and seventh papers investigate a speaker separation technique developed for American English. It was found that the technique could be used to separate Swedish speakers and that it is robust against professional imitations. Paper eight investigates how age and hearing impact upon earwitness reliability. This study shows that a senior citizen with corrected hearing can be as reliable an earwitness as a younger adult with no hearing problem, but suggests that a witness' general cognitive skill deterioration needs to be considered when assessing a senior citizen's earwitness evidence. On the basis of the studies a model of speaker recognition is presented, based on the face recognition model by V. Bruce and Young (1986; British Journal of Psychology, 77, pp. 305 - 327) and the voice recognition model by Belin, Fecteau and Bédard (2004; TRENDS in Cognitive Science, 8, pp. 129 - 134). The merged and modified model handles both familiar and unfamiliar voices. The findings presented in this Thesis, in particular the findings of the individual papers in Part II, have implications for criminal cases in which speaker recognition forms a part. The findings feed directly into the growing body of forensic phonetic and forensic linguistic research.
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| 7. |
- Eriksson Krutrök, Moa
(författare)
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Digital aftermaths of terror : reactions to terrorist attacks on twitter
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. This thesis explores digital public reactions to terrorist attacks, and specifically how discourses on terrorism become articulated on social media. The overarching aim of the thesis is to explore the reactions spread on social media following attacks, and how these digital platforms may alter or transform the ways in which such attacks are collectively understood and interpreted. It explores issues relating to Twitter as a platform for backchannel meaning making, for downplaying fear mongering practices, the ways different terrorist attacks become co-articulated, as well as the divided attention of networked publics during terror-related events.Methods. The thesis is made up of four individual papers, each exploring digital reactions to different terrorist attacks on Twitter. The cases include the Utøya massacre in Norway 2011, the Stockholm lorry attack in 2017, 12 different attacks occurring between 2015-2017 in Europe (multi-case study), and the terrorist attack in Sinai, Egypt and the subsequent false alarm about a suspected terrorist attack on Oxford Street Underground station in London, UK, occuring on the same day in 2017. A combination of methods used in this thesis include network analysis of hashtag co-occurrences, and thematic analysis of prominent themes in tweets, using discourse theory as its analytical framework in the qualitative readings. Results. The findings of the thesis suggest that discourses on terrorism on social media are shaped by the specific logics present in the connective action of networked publics. The political action of digital audiences is performed in a personalised way that shapes terrorism discourse. How terrorism is understood is influenced by collective ideas of how societies become affected by trauma or resilience, and digital communities engage in downplaying or amplifying practices for such articulations. Prevailing spatial and temporal contexts alsomatter for the ways in which terrorist attacks are understood and reimagined. The (real or perceived) closeness to the attack, the interrelatedness of attacks, and aspects of virality of information plays a role in how terror discourses become articulated in digital spaces. Conclusion. This thesis makes theoretical and empirical contributions to the understanding of how digital audiences articulate terrorism discourse in the aftermath of terrorist attacks. It stresses that emotive personal expressions on social media should be understood as a highly politicised reaction, relating to a vast range of issues, such as immigration control, nationalism, or an increased prevalence of everyday racism. On social media, audiences may both amplify or downplay attention to specific terrorist attacks, and, as such, may choose to provide (or not provide) attention. Social media may thus function as a space for everyday political action in times of terrorism.
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| 8. |
- Eriksson, Lina J. K.
(författare)
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An Exploration of the Behavioral Inhibition System (BIS), Response Inhibition, and Possible Implications in Sports
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Large parts of human behaviors are oriented towards achieving a particular goal. Motivational factors in the form of approach and avoidance motivated behavior and executive functions (EFs) such as inhibition are central for goal-directed behavior. There are individual differences in the inhibition of prepotent behavior and the Behavioral Inhibition System (BIS) can be viewed as a neuropsychological system that has been proposed to be a personality trait that explains those individual differences. Inhibition is an EF that is involved in the control of impulses and enable us to choose how to react and behave. Sport is a context in which the cognitive demands can be high and there is a growing body of research trying to pinpoint the cognitive mechanisms behind superior athletic performance. Response inhibition is suggested to be one of the mechanisms that is of importance for performance in sport.The general aim of this thesis was to explore the BIS, response inhibition and the possible implications in sports. A theoretical framework of approach and avoidance motivation, the revised RST (Gray & McNaughton, 2000; McNaughton & Corr, 2004) was combined with a paradigm for assessment of response inhibition; the stop-signal paradigm (Logan & Cowan, 1984). In addition, different instruments for assessment of the BIS was investigated and designs of the stop-signal task for assessment of response inhibition was used. Study I and III aimed to examine the relationship between response inhibition and the BIS. Study I used a sample of non-athletes and Study III used a sample of non-athletes, and athletes from two different interceptive sports, biathlon and alpine skiing. The aim of Study II was to test the factor structure of a Swedish version of the Reinforcement Sensitivity Theory of Personality Questionnaire (RST – PQ; Corr & Cooper, 2016). The results from Study I indicated that when the ability to inhibit prepotent response and behavioral precision (i.e., accuracy) is central for task performance, higher levels of BIS could be a vulnerability factor when the individual’s inhibitory ability simultaneously is poor. Due to ceiling effects in the variable accuracy, this was not possible to replicate in Study III. The results in Study II suggest that the RST-PQ has considerable promise since it, for example, provides an opportunity to distinguish between the individual differences between fear and anxiety, although there were issues concerning the convergent validity. Study III showed that athletes with experience in interceptive sports do not outperform non-athletes on response inhibition. The implications of these results are that it is possible that other aspects than being an athlete or non-xathlete need to be considered and that individual differences in the BIS could be one of these aspects.Taken together, results from these three studies indicated that that it is possible to combine a theoretical framework of approach and avoidance motivation and a paradigm for the assessment of response inhibition, the stop-signal paradigm, with the purpose of exploring the BIS, response inhibition and possible implications in sport. It has also showed the complexity with using self-report instruments for assessment of neuropsychological systems that, in theory, underlies personality and the difficulties with using SSTs for assessment of an estimated measure (i.e., SSRT) of response inhibition. By exploring the BIS and response inhibition, this thesis offers an approach to view sport expertise and show the value of focusing on individual differences in the personality trait BIS since, at least theoretically, the BIS has the potential to serve as an explanation for variations in response inhibition and the possible association with behavioral precision (i.e., accuracy).
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| 9. |
- Eriksson, Maria J
(författare)
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Noninvasive haemodynamic evaluation of aortic valve prostheses : Doppler echocardiographic studies at rest and during exercise
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present series of investigations was designed to supply information on in vivo pressure-flow relationships and to analyse the incidence of regurgitation in different heart valve prostheses in the aortic position. Patients and methods: The study population comprised 185 patients with mechanical Björk-Shiley Monostrut prostheses, 54 patients with Biocor stented porcine bioprostheses, 50 patients with extended Biocor stentless bioprostheses and 59 patients with cryopreserved aortic homografts. Transvalvular pressure differences and volume flow estimates were derived noninvasively from Doppler measurement of blood velocity across the prosthesis and in the left ventricular outflow tract. Measurements were performed at rest and during supine symptom-limited bicycle exercise. Aortic regurgitation was evaluated semi-quantitatively using colour flow Doppler and continuous-wave Doppler. Patients were investigated after surgery, prior to hospital discharge (baseline) and approximately every year postoperatively. Results: Reference values for baseline Doppler echocardiographic variables for normally functioning prostheses in the aortic position were established. The newly-developed extended Biocor stentless bioprosthesis showed low pressure differences associated with a significant regression of left ventricular hypertrophy during the first six months after aortic valve replacement, and low incidence of aortic regurgitation. A decrease of 40% in pressure differences from baseline to six-month examination was observed in patients with stentless prostheses, partly depending on different haemodynamic states of patients early after the operation. Subcoronarily implanted cryopreserved aortic homografts. demonstrated excellent haemodynamic performance with low pressure differences and large effective orifice areas. Timerelated increasing risk of progression of aortic regurgitation observed during follow-up justifies more frequent echocardiographic monitoring in patients with homograft valves, especially when aortic regurgitation is detected on baseline examination. Different types of prosthesis of similar size were compared at rest and during exercise. The lowest pressure differences and the largest effective orifice areas were demonstrated in homograft valves, followed by extended Biocor stentless bioprostheses. With a 65-70% increase in cardiac output induced by exercise, pressure differences and valve resistance increased significantly while effective orifice area remained unchanged in all four prosthesis types studied. Doppler-derived haemodynamic variables can be obtained at rest and during supine symptom-limited exercise with low variability. The exercise performed in this study was interrupted at a high level of subjective exertion; thus the exercise pressure differences obtained are likely to represent maximal values for pressure differences occurring in the patients' daily activities. Conclusions: In patients undergoing aortic valve replacement, Doppler echocardiography at rest provides basic information on prosthetic valve function. In addition, exercise Doppler echocardiography provides further valuable insight into valve haemodynamics during physiologically increased volume flow. These results can be obtained with low variability. The stentless porcine bioprostheses and cryopreserved aortic homograft valves exhibit low valve resistance to flow at rest and exercise, reflecting the low haemodynamic load imposed by these valves on the left ventricle.
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| 10. |
- Eriksson, Tove L J
(författare)
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Dust mite allergens : cloning, characterisation and T-cell responses
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The number of allergens that have been cloned has increased dramatically during the last 10 years, and today, over 400 allergen sequences are available in the databases. In addition, at least 15 dust mite allergens have been characterised. The group 1 and 2 mite allergens are of great importance, since up to 90% of all mite sensitised individuals have IgE antibodies against those proteins. This thesis focuses on cloning and characterisation of allergens from three different dust mite species, Acarus siro, Tyrophagus putrescentiae and Lepidoglyphus destructor. Two low molecular mass allergens from A. siro were identified and characterised. A 15 kDa component was cloned and showed high sequence homology with fatty acid-binding proteins (FABP). The allergen was named Aca s 13, was produced in E. coh as a recombinant protein and was shown to be detected by 23% of the A. siro sensitised individuals. Amino acid sequencing of peptides from the 17 kDa component also revealed sequence homology to FABP's and Aca s 13, although the 17 kDa component was not classified as an isoform of Aca s 13 due to the size difference and the fact that only a partial sequence was revealed. The cDNA encoding a group 2 allergen from T putrescentiae was sequenced and the deduced sequence consists of 126 amino acids with a 15 amino acid leader peptide. The allergen was named Tyr p 2 due to its homology (about 40% sequence identity) to other mite group 2 allergens. Tyr p 2 was expressed in E. coh and shown to be detected by sera from T putrescentiae sensitised individuals. The lgE binding of recombinant Tyr p 2 and the previously cloned Lep d 2 was evaluated in the Pharmacia RAST CAP system and was cornpared with the lgE binding to the corresponding commercial extracts. Among the L. destructor and T putrescentiae sensitised subjects, 73.3% and 60.5% were positive to rLep d 2 and rTyr p 2, respectively, in the CAP assay. Although rLep d 2 and rTyr p 2 are able do identify the majority of the subjects sensitised to L. destructor and T putrescentiae, respectively, it is obvious that additional recombinant allergens are needed to get reliable diagnostic tools based on recombinant allergens. Therefore, a cDNA phage display expression library was constructed and screened against sera from L. destructor allergic patients, using a modified selection method. Three new allergens were identified, Ld 5 (originating from a partial Lep d 5 clone), Lep d 7 and Lep d 13. The allergens were expressed in E. coh and were recognised by 9%, 62% and 13% of sera from 45 L. destructor sensitised subjects, respectively. An investigation of T-cell responses to the two cloned isoforms of Lep d 2 (01 and 02), a mutant form of Lep d 2.01 (Lep d 2.6Cys) with a highly reduced IgE reactivity, as well as peptides derived from Lep d 2, was performed in order to investigate the cellular responses to Lep d 2. Isoform 01 evoked greater proliferation of PBMC than isoform 02 and the response to rLep d 2.6Cys was intermediate. Although rLep d 2.6Cys evoked a lower T-cell response than rLep d 2.01, it may be a good candidate for immunotherapy because of its low IgE reactivity. Two immunodominant peptides corresponding to amino acid residue 11-25 and 61-75 were identified and are likely to contain the immunodominant T-cell epitopes of Lep d 2. There was a correlation between the proliferation to rLep d 2.01 and IFN- gamma production in the group of non-allergic controls, suggesting that a strong proliferative response is accompanied by a Th 1 response in non-allergic individuals. In conclusion, five new dust mite allergens have been cloned and characterised. These allergens may be useful to improve the diagnosis of dust mite allergy. The T-cell studies indicated that modified recombinant allergens or peptides may be useful to improve current schemes of allergen-specific immunotherapy of dust mite allergy.
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