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- Dahlberg, Tobias, 1990-
(författare)
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KNOW YOUR ENEMY : Characterizing Pathogenic Biomaterials Using Laser Tweezers
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diseases caused by pathogenic agents such as bacteria and viruses result in devastating costs on personal and societal levels. However, it is not just the emergence of new diseases that is problematic. Antibiotic resistance among bacteria makes uncomplicated infections difficult and lethal. Resilient disease-causing spores spread in hospitals, the food industry, and water supplies requiring effective detection and disinfection methods. Further, we face complex neurological diseases where no effective treatment or diagnostic methods exist. Thus, we must increase our fundamental understanding of these diseases to develop effective diagnostic, detection, disinfection, and treatment methods.Classically, the methods used for detecting and studying the underlying mechanics of pathogenic agents work on a large scale, measuring the average macroscopic behavior and properties of these pathogens. However, just as with humans, the average behavior is not always representative of individual behavior. Therefore, it is also essential to investigate the characteristics of these pathogens on a single cell or particle level. This thesis develops and applies optical techniques to characterize pathogenic biomaterial on a single cell or particle level. At the heart of all these studies is our Optical Tweezers (OT) instrument. OT are a tool that allows us to reach into the microscopic world and interact with it. Finally, by combining OT with other experimental techniques, we can chemically characterize biomaterials and develop assays that mimic different biological settings. Using these tools, we investigate bacterial adhesion, disinfection, and detection of pathogenic spores and proteins.Hopefully, the insights of these studies can lessen the burden on society caused by diseases by helping others develop effective treatment, diagnostic, detection, and disinfection methods in the future.
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| 2. |
- Sjödahl, Krister, et al.
(författare)
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Airborne exposures and risk of gastric cancer : a prospective cohort study.
- 2007
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 120:9, s. 2013-8
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Tidskriftsartikel (refereegranskat)abstract
- There is an unexplained male predominance among patients with gastric cancer, and many carcinogens are found in male-dominated dusty occupations. However, the relation between occupational exposures and risk of gastric cancer remains unclear. To investigate whether airborne occupational exposures might influence the risk of noncardia gastric cancer, we used a large, prospective cohort study of male Swedish construction workers. These workers were, during the period 1971-1993, regularly invited to health examinations by a nationwide occupational health service organization. Data on job titles and other variables were collected through self-administered questionnaires and forms completed by the health organization's staff. Industrial hygienists assessed 12 specific airborne occupational exposures for 200 job titles. Gastric cancer, death or emigration occurring during follow-up in 1971-2002 were identified by linkage to the Swedish registers of Cancer, Causes of Death and Total Population, respectively. Incidence rate ratios (IRR) and 95% confidence intervals (CI), adjusted for attained age, tobacco smoking, calendar period and body mass, were derived from Cox regression. Among 256,357 cohort members, contributing 5,378,012 person-years at risk, 948 noncardia gastric cancers were identified. Increased risk of this tumor was found among workers exposed to cement dust (IRR 1.5 [95% CI 1.1-2.1]), quartz dust (IRR 1.3 [95% CI 1.0-1.7]) and diesel exhaust (IRR 1.4 [95% CI 1.1-1.9]). Dose-response relations were observed for these exposures. No consistent positive associations were found regarding exposure to asbestos, asphalt fumes, concrete dust, epoxy resins, isocyanates, metal fumes, mineral fibers, organic solvents or wood dust. In conclusion, this study provides some support to the hypothesis that specific airborne exposures increase the risk of noncardia gastric cancer.
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| 3. |
- Sjödahl, Krister
(författare)
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Aspects of the etiology of gastric adenocarcinoma
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gastric adenocarcinoma is the fourth most common malignancy and the second leading cause of cancer death in the world. Tremendous effort has been made to look into the causation of gastric cancer. Etiological research plays a key role in identifying possible preventive and interventional measures. This thesis is based on four large prospective, population-based cohort studies, focusing on environmental risk factors for gastric cancer other than infection with Helicobacter pylori. In the first study, the relations of tobacco smoking and alcohol to gastric cancer were investigated in a public health survey of the adult population of the Nord-Trondelag County in Norway (HUNT-1). During follow-up, we identified 251 new cases of gastric cancer. The risk of noncardia gastric cancer was almost twice as high in daily smokers as in non-smokers. Earlier age at initiation of daily smoking was associated with an increased risk of non-cardia gastric cancer, independently of adjustment for duration of smoking, suggesting a dose-response relation with earlier onset of smoking. Excessive smoking combined with high alcohol intake was associated with a nearly 5-fold increase in risk of non-cardia gastric cancer, compared to non-users. In the second study, we hypothesized that specific airborne exposures, which often occur in the male-dominated construction industry, such as dust, fumes, and solvents, could be inhaled and swallowed and have a direct harmful effect on the gastric mucosa. To elucidate the relation between such exposures and risk of gastric cancer in a male-dominated industry, we used prospectively collected data from the Swedish Construction Workers Cohort. In total, 948 incident cases of gastric cancer were identified. There were seemingly dose-response positive associations between exposure to cement dust, quartz dust, and diesel exhaust and risk of gastric cancer. Increased risk of this tumor was found among workers exposed to cement dust (IRR 1.5 [95% CI 1.1-2.1]), quartz dust (IRR 1.3 [95% CI 1.0-1.7]), and diesel exhaust (IRR 1.4 [95% CI 1.1-1.9]). In the third study, we prospectively investigated the influence of body mass index (BMI) and recreational physical activity on risk of gastric cancer in the HUNT-1 cohort. No statistically significant association was found between different levels of BMI and risk of gastric cancer. A statistically significant 40-50% decrease in the risk of gastric cancer was seen among persons who had at least a moderate level of recreational physical activity, and a dose-response relation was indicated. In the fourth study, we assessed the effect of dietary salt intake on the risk of gastric cancer in a low-incidence Western region, again based on the HUNT-1 cohort. There was no statistically significant association between level of intake of salted foods and risk of gastric adenocarcinoma. This result highlights the question as to whether cofactors more prevalent in high-incidence populations, such as other dietary factors and Helicobacter pylori infection, interact with salt in producing a potentially carcinogenic effect on the gastric mucosa, or whether previously reported positive associations might have been an artifact of residual confounding by such factors.
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