Development of fluorescence-based techniques for quantitative measurements of combustion species

The work presented in this thesis covers how laser-induced fluorescence (LIF) and photofragmentation laser-induced fluorescence (PF-LIF) can be used to determine quantitative species concentrations in different combustion environments. To attain species concentrations with LIF it is of vital importance to investigate the influence of collisional quenching on the fluorescence signal strength, which can be done by measuring the fluorescence lifetime. A method for simultaneous measurements of fluorescence lifetimes of two species present along a line is described and discussed. The experimental setup is based on picosecond laser pulses from a dual optical parametric generator/amplifier (OPG/OPA) system tuned to excite two different species, whose fluorescence signals are detected with a streak camera. The concept is demonstrated for fluorescence lifetime measurements of CO and OH in laminar methane/air flames on a Bunsen-type burner. The measured one-dimensional lifetime profiles generally agree well with lifetimes calculated from quenching cross sections found in the literature and quencher concentrations predicted by the GRI 3.0 chemical mechanism. For OH there is a systematic deviation of ~30% between calculated and experimental lifetimes in the product zone. It is found that this discrepancy is mainly due to the adiabatic assumption regarding the flame and uncertainty in H2O quenching cross section. The second technique, i.e. PF-LIF, is used to study H2O2 and HO2, which both are molecules lacking accessible bound excited states. Here, a pump laser pulse of 266-nm wavelength dissociates the molecules into OH fragments, which after a short time delay (nanosecond time scale), are probed with LIF using a second laser pulse tuned to an OH absorption line. PF-LIF is for the first time used for two-dimensional imaging of HO2 in laminar flames and H2O2 in an homogenous charged compression (HCCI) engine. In methane/air flames on a Bunsen-type burner, relative species concentrations of HO2, H2O2 and CH3O2 are achieved via comparison of experimental signal profiles with simulated concentrations predicted by the Konnov detailed C/H/N/O reaction mechanism. An interfering OH signal contribution is observed in the product zone and found to originate from hot CO2. In the HCCI experiments, quantitative H2O2 concentrations at different piston positions are attained via an on-line calibration procedure. In terms of mass fraction levels, the crank-angle resolved experimental data agree well with profiles resulting from simulations using the software Digital Analysis of Reaction System (DARS), while shapes and profiles deviate slightly, which mainly is due to signal interference from HO2

Ectopic germinal center formation in Sjögren’s syndrome: Significance of lymphoid organization

This thesis is based on the following papers, which will be referred to in the text by their Roman numerals: I. Salomonsson S, Jonsson MV, Skarstein K, Hjälmström P, Wahren-Herlenius M, Jonsson R. Cellular basis of ectopic germinal center formation and autoantibody production in the target organ of patients with Sjögren’s syndrome. Arthritis & Rheumatism 2003;48(11):3187-201. II. Jonsson MV, Szodoray P, Jellestad S, Jonsson R, Skarstein K. Association between circulating levels of the novel TNF family members APRIL and BAFF and lymphoid organization in primary Sjögren’s syndrome. Journal of Clinical Immunology, 2005;25(3):189-201. III. Jonsson MV, Skarstein K, Jonsson R, Brun JG. Germinal centers in primary Sjögren’s syndrome indicate a certain clinical immunological phenotype. Submitted. IV. Jonsson MV, Salomonsson S, Gunnvor Øijordsbakken, Skarstein K. Elevated serum levels of soluble E-cadherin in patients with primary Sjögren’s syndrome. Scandinavian Journal of Immunology, 2005;62(6):552-9. V. Jonsson MV, Delaleu N, Brokstad KA, Berggreen E, Skarstein K. Impaired salivary gland function in NOD mice – association with changes in cytokine profile but not with salivary gland histopathology. Arthritis & Rheumatism, in press.Sjögren’s syndrom (SS) is an autoimmune, chronic inflammatory disorder predominantly affecting the salivary and lacrimal glands. The overall aim of this study was to determine clinicopathological features in human and murine disease with regard to organization of ectopic lymphoid tissue, and to explore possible strategies for detection of patients at increased risk for extra-glandular manifestations. Mononuclear cell infiltrates in the shape of germinal centers (GC) were observed in the salivary glands of approximately 1/4th of patients. Phenotypic markers for GC components such as T and B cells, proliferating cells, follicular dendritic cells and plasma cells confirmed the ectopic GC formation. The pattern and distribution of homing and retentive chemokines CXCL12, CXCL13 and CCL21, and adhesion molecules/integrin pairs ICAM/LFA and VCAM/VLA, was described in various lymphoid organizations in minor salivary glands. In addition, local autoantibody production was detected and correlated with serum levels. Focal infiltrates and GC could be observed within the same gland, and were separated by altered B and T cell ratios, higher degree of proliferation and the localization of plasma cells in the periphery of infiltrates. Serum levels of BAFF and APRIL were elevated in pSS, and were in part linked to focus score, elevated serum IgG and autoantibody levels. In a large cohort of pSS, ectopic GC were also associated with higher focus scores, lower mean un-stimulated salivary secretion, Ro/SSA and La/SSB autoantibodies, elevated RF-titres and increased serum IgG. Not all morphological GC could be confirmed by CD21/CD23/CD35 labeling, but clinical features remained comparable. E-cadherin, an adhesion molecule important for epithelial tissue integrity, was investigated in minor salivary glands. E-cadherin is the ligand of integrin αEβ7/CD103 and lymphocytes expressing this integrin were increased in SS compared to non-SS. E-cadherin+ infiltrating cells were identified as CD68+ macrophages. Serum levels of sE-cadherin were increased in pSS compared to healthy blood donors and most likely mirror the chronic inflammatory state. The non-obese diabetic (NOD) mouse is an animal model of SS. We observed significant changes in inflammation between 8 and 17 weeks of age, while hyposalivation was first observed between 17 and 24 weeks. In 1/3rd of mice older than 17 weeks, proliferating cells were observed in the focal infiltrates. Significant differences were detected in serum cytokine levels of IL-2, IL-5 and GM-CSF, and IL-4 and TNF-α in saliva. Salivary secretion correlated with IL-4, IFN-γ and TNF-α levels in saliva of NOD mice, but not with inflammatory changes in the salivary glands. Focal sialadenitis preceded hyposalivation, which occurred without a significant change in inflammation in NOD mice. Proliferating inflammatory cells indicate contribution of local factors in progression of SS-like disease. In conclusion, ectopic germinal centers occur in a sub-group of patients with SS and are characterized by autoantibody production, progressive disease and increased serum IgG. It remains unclear whether the observed GC are a result of long-standing inflammation or indeed have functional properties and thus play an active role in the pathogenesis. A future challenge will be to identify and target trafficking molecules which drive the chronic inflammation in SS, without affecting migration and function of leukocytes required for protective immunity

Investigation of photochemical effects in flame diagnostics with picosecond photofragmentation laser-induced fluorescence

Photofragmentation laser-induced fluorescence (PFLIF) is for the first time performed based on picosecond laser pulses for detection of hydroperoxyl radicals (HO2) in a stoichiometric laminar methane/air flame. Photofragmentation is performed with a pump laser pulse of 80 ps duration and a wavelength of 266 nm, whereupon the produced OH photofragments are detected by a second picosecond probe laser pulse, inducing fluorescence via excitation in the A2Σ+(v = 1) ← X2Π(v = 0) band of OH near 283 nm. Excitation spectra of the OH photofragments formed in the reaction zone were recorded for pump-probe delays ranging from 0 to 5 ns. The spectra suggest that the population distribution of the nascent OH fragments is rotationally cold and that it takes on the order of 5 ns for the nascent non-equilibrium rotational distribution to relax into a thermal distribution. The radial OH-fragment distribution was extracted from spectral images (radial position versus emission wavelength) recorded at six different pump-probe delays. Photochemical OH production was observed both in the reaction zone and the product zone. Comparison with a kinetic model for OH production suggests that more than 20% of the oxygen fragments produced by photolysis in the reaction zone are formed in the excited 1D state, explaining a very rapid initial signal growth. The OH-production model was also compared with previous reaction-zone data, acquired with nanosecond laser pulses in the same flame, indicating that no O(1D), but only O(3P), is formed. A plausible explanation of the discrepancy between the two results is that the picosecond pulses, having more than two-orders of magnitude higher irradiance than the nanosecond pulses used in the previous study, might cause 2-photon photodissociation, allowing production of O(1D). In terms of flame diagnostics with PFLIF, it is concluded that a setup based on nanosecond laser pulses, rather than picosecond pulses, appears preferable since photochemical OH production in the reaction zone can be avoided while for short delay times the ratio between the photofragment signal and the photochemical interference in the product zone, stemming from CO2 photolysis, is sufficiently large to clearly visualize the photofragments

Analysis of simultaneous space-time clusters of Campylobacter spp. in humans and in broiler flocks using a multiple dataset approach

<p>Abstract</p> <p>Background</p> <p>Campylobacteriosis is the most frequently reported zoonosis in the EU and the epidemiology of sporadic campylobacteriosis, especially the routes of transmission, is to a great extent unclear. Poultry easily become colonised with <it>Campylobacter </it>spp., being symptom-less intestinal carriers. Earlier it was estimated that internationally between 50% and 80% of the cases could be attributed to chicken as a reservoir. In a Norwegian surveillance programme all broiler flocks under 50 days of age were tested for <it>Campylobacter </it>spp. The aim of the current study was to identify simultaneous local space-time clusters each year from 2002 to 2007 for human cases of campylobacteriosis and for broiler flocks testing positive for <it>Campylobacter </it>spp. using a multivariate spatial scan statistic method. A cluster occurring simultaneously in humans and broilers could indicate the presence of common factors associated with the dissemination of <it>Campylobacter </it>spp. for both humans and broilers.</p> <p>Results</p> <p>Local space-time clusters of humans and broilers positive for <it>Campylobacter </it>spp. occurring simultaneously were identified in all investigated years. All clusters but one were identified from May to August. Some municipalities were included in clusters all years.</p> <p>Conclusions</p> <p>The simultaneous occurrence of clusters of humans and broilers positive for <it>Campylobacter </it>spp. combined with the knowledge that poultry meat has a nation-wide distribution indicates that campylobacteriosis cases might also be caused by other risk factors than consumption and handling of poultry meat.</p> <p>Broiler farms that are positive could contaminate the environment with further spread to new broiler farms or to humans living in the area and local environmental factors, such as climate, might influence the spread of <it>Campylobacter </it>spp. in an area. Further studies to clarify the role of such factors are needed.</p

To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?-a systematic review protocol

Background: Silviculture and land-use change has reduced the amount of natural forest worldwide and left what remains confined to isolated fragments or stands. To understand processes governing species occurrence in such stands, much attention has been given to stand-level factors such as size, structure, and deadwood amount. However, the surrounding matrix will directly impact species dispersal and persistence, and the link between the surrounding landscape configuration, composition and history, and stand-level species occurrence has received insufficient attention. Thus, to facilitate optimisation of forest management and species conservation, we propose a review addressing 'To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?'.Methods: The proposed systematic review will identify and synthesise relevant articles following the CEE guidelines for evidence synthesis and the ROSES standards. A search for peer-reviewed and grey literature will be conducted using four databases, two online search engines, and 36 specialist websites. Identified articles will be screened for eligibility in a two-step process; first on title and abstract, and second on the full text. Screening will be based on predefined eligibility criteria related to a PECO-model; population being boreal and hemi-boreal forest, exposure being fragmentation, comparator being landscapes with alternative composition, configuration, or history, and outcome being occurrence (i.e., presence and/or abundance) of conservation-relevant species. All articles that pass the full-text screening will go through study validity assessment and data extraction, and be part of a narrative review. If enough studies prove comparable, quantitative meta-analyses will also be performed. The objective of the narrative review and the meta-analyses will be to address the primary question as well as six secondary questions, and to identify important knowledge gaps

Serum fatty acid profile does not reflect seafood intake in adolescents with atopic eczema.

AIM: Long-chain polyunsaturated fatty acids (LCPUFAs) are immunomodulatory, but their role in allergy development is controversial. We investigated whether proportions of LCPUFAs in serum phospholipids were related to allergic diagnosis, seafood intake and LCPUFA proportions in cord blood.</br></br> METHODS: Serum was obtained from 148 birth cohort children at 13 years of age. Forty had atopic eczema, 53 had respiratory allergy, and 55 were nonallergic. Proportions of LCPUFAs were determined in serum phospholipids; cord blood from 128 of the individuals was previously analysed. Seafood intake was estimated using questionnaires.</br></br> RESULTS: Allergic and nonallergic individuals did not differ significantly regarding individual LCPUFAs. However, arachidonic acid over docosahexaenoic acid (DHA) ratio was higher in allergic, compared with nonallergic, adolescents. In nonallergic individuals, LCPUFA proportions in cord serum and adolescent serum correlated weakly. In individuals with atopic eczema and respiratory allergy, these correlations were weak or absent. A moderate correlation between seafood intake and serum DHA was seen in nonallergic individuals and those with respiratory allergy, but not in those with atopic eczema.</br></br> CONCLUSION: Serum LCPUFA pattern was similar in allergic and nonallergic adolescents. Fatty acid metabolism may be altered in atopic eczema subjects, suggested by poor correlations between fatty acid intake and serum levels

Understanding fatigue in Sjögren’s Syndrome: Outcome measures, biomarkers and possible interventions

Sjögren’s syndrome (SS) is an autoimmune disease affecting the salivary and lacrimal glands. Symptoms range from dryness to severe extra-glandular disease involving manifestations in the skin, lungs, nervous system, and kidney. Fatigue occurs in 70% of patients, characterizing primary SS (pSS) and significantly impacting the patient’s quality of life. There are some generic and specific instruments used to measure fatigue in SS. The mechanisms involved with fatigue in SS are still poorly understood, but it appears fatigue signaling pathways are more associated with cell protection and defense than with pro-inflammatory pathways. There are no established pharmacological treatment options for fatigue in pSS. So far, exercise and neuromodulation techniques have shown positive effects on fatigue in pSS. This study briefly reviews fatigue in pSS, with special attention to outcome measures, biomarkers, and possible treatment options.publishedVersio

Lymphoid organisation in labial salivary gland biopsies is a possible predictor for the development of malignant lymphoma in primary Sjögren's syndrome

Objective The development of non-Hodgkin's lymphoma (NHL) confers a high risk of mortality in primary Sjogren's syndrome (pSS) patients, but the sensitivity and specificity of proposed lymphoma predictors are insufficient for practical use. The performance of lymphoid organisation in the form of germinal centre (GC)-like lesions was evaluated in labial salivary gland biopsies taken at pSS diagnosis as a potential lymphoma-predicting biomarker. Methods Labial salivary gland tissue biopsies available from two Swedish pSS research cohorts (n = 175) were re-evaluated by light microscopy in a blind study in order to identify GC-like structures as a sign of ectopic lymphoid tissue formation and organisation. A linkage study was performed with the Swedish Cancer Registry for lymphoma identification. The risk of developing NHL in GC-positive patients in comparison with GC-negative patients was evaluated using Kaplan-Meier statistics and log-rank test. Associations between GC-like structures and clinical and/or laboratory disease markers were also determined using. 2 or Fisher's exact tests. Results At diagnosis, 25% of pSS patients had GC-like structures in their salivary glands. Seven of the 175 patients studied (14% GC+ and 0.8% GC-) developed NHL during 1855 patient-years at risk, with a median onset of 7 years following the initial diagnostic salivary gland biopsy. Six of the seven patients had GC-like structures at diagnosis; the remaining patient was GC negative at the time of diagnosis (p=0.001). Conclusions The detection of GC-like structures by light microscopy in pSS diagnostic salivary biopsies is proposed as a highly predictive and easy-to-obtain marker for NHL development. This allows for risk stratification of patients and the possibility to initiate preventive B-cell-directed therapy

Impaired vascular responses to parasympathetic nerve stimulation and muscarinic receptor activation in the submandibular gland in non-obese diabetic mice

Introduction Decreased vascular responses to salivary gland stimulation are observed in Sjögren's syndrome patients. We investigate whether impaired vascular responses to parasympathetic stimulation and muscarinic receptor activation in salivary glands parallels hyposalivation in an experimental model for Sjögren's syndrome. Methods Blood flow responses in the salivary glands were measured by laser Doppler flowmeter. Muscarinic receptor activation was followed by saliva secretion measurements. Nitric oxide synthesis-mediated blood flow responses were studied after administration of a nitric oxide synthase inhibitor. Glandular autonomic nerves and muscarinic 3 receptor distributions were also investigated. Results Maximal blood flow responses to parasympathetic stimulation and muscarinic receptor activation were significantly lower in nonobese diabetic (NOD) mice compared with BALB/ c mice, coinciding with impaired saliva secretion in nonobese diabetic mice (P < 0.005). Nitric oxide synthase inhibitor had less effect on blood flow responses after parasympathetic nerve stimulation in nonobese diabetic mice compared with BALB/c mice (P < 0.02). In nonobese diabetic mice, salivary gland parasympathetic nerve fibres were absent in areas of focal infiltrates. Muscarinic 3 receptor might be localized in the blood vessel walls of salivary glands. Conclusions Impaired vasodilatation in response to parasympathetic nerve stimulation and muscarinic receptor activation may contribute to hyposalivation observed in nonobese diabetic mice. Reduced nitric oxide signalling after parasympathetic nerve stimulation may contribute in part to the impaired blood flow responses. The possibility of muscarinic 3 receptor in the vasculature supports the notion that muscarinic 3 receptor autoantibodies present in nonobese diabetic mice might impair the fluid transport required for salivation. Parasympathetic nerves were absent in areas of focal infiltrates, whereas a normal distribution was found within glandular epithelium.publishedVersio

Preoperative biomarkers related to inflammation may identify high-risk anastomoses in colorectal cancer surgery : explorative study

Anastomotic leakage is a major complication after colorectal surgery, presumed to correspond with a process of failed wound healing, involving inflammation. Circulating levels of inflammation-related biomarkers were investigated in preoperative samples from 41 patients with leakage, who had elective treatment with a primary anastomosis for non-disseminated colorectal cancer, matched to 41 complication-free controls. A total of 15 inflammation-related proteins were elevated before surgery in patients with rectal cancer with leakage, of which C-X-C motif chemokine 6 and C-C motif chemokine 11 remained significantly increased after controlling for multiplicity. As a corresponding expression pattern difference did not emerge when tissue adjacent to the anastomosis was evaluated with immunohistochemistry, findings may reflect a systemic rather than a local host response. While these findings require validation before implementation into surgical practice, they highlight the need for further translational investigations as a promising research area to help decrease leakage rates. Background Colorectal anastomotic leakage can be considered a process of failed wound healing, for which related biomarkers might be a promising research area to decrease leak rates. Methods Patients who had elective surgery with a primary anastomosis for non-metastatic colorectal cancer, at two university hospitals between 1 January 2010 and 31 December 2015 were included. Patients with an anastomotic leak were identified and matched (1:1) to complication-free controls on the basis of sex, age, tumour stage, tumour location, and operating hospital. Preoperative blood samples were analysed by use of protein panels associated with systemic or enteric inflammation by proteomics, and enzyme-linked immunosorbent assays. Multivariable projection methods were used in the statistical analyses and adjusted for multiple comparisons to reduce false positivity. Rectal cancer tissue samples were evaluated with immunohistochemistry to determine local expression of biomarkers that differed significantly between cases and controls. Results Out of 726 patients undergoing resection, 41 patients with anastomotic leakage were matched to 41 controls. Patients with rectal cancer with leakage displayed significantly elevated serum levels of 15 proteins related to inflammation. After controlling for a false discovery rate, levels of C-X-C motif chemokine 6 (CXCL6) and C-C motif chemokine 11 (CCL11) remained significant. In patients with colonic cancer with leakage, levels of high-sensitivity C-reactive protein (hs-CRP) were increased before surgery. Local expression of CXCL6 and CCL11, and their receptors, were similar in rectal tissues between cases and controls. Conclusion Patients with anastomotic leakage could have an upregulated inflammatory response before surgery, as expressed by elevated serological levels of CXCL6 and CCL11 for rectal cancer and hs-CRP levels in patients with colonic cancer respectively. Preoperative inflammation-related serum proteins were evaluated in a case-control study of 41 patients with anastomotic leakage matched 1:1 with 41 complication-free controls. The chemokines C-X-C motif chemokine 6 and C-C motif chemokine 11 were significantly increased before surgery in patients with rectal cancer and leakage, a finding requiring further validation.Peer reviewe