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| 2. |
- Lagö, Thomas L, et al.
(författare)
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On Robust Estimation of Water Current Using a Frequency Domain Approach : The Symmiktos Method
- 1994
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Konferensbidrag (refereegranskat)abstract
- The estimation of water current by using acoustic Doppler current meters (ADCM) is a well-known method. Determination of the water current is based on the Doppler shift caused by the movement of small particles in the water, related to the current as an average. These movements cause a Doppler shift with an assumed Gaussian-shaped distribution in time. This assumption is valid for clean water and water where one particle size dominates the scattering and thereby the Doppler shift. If many bubble size are involved in the scattering, the Gaussian-based estimators may generate errors.
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| 3. |
- Lagö, Thomas L, et al.
(författare)
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Performance of an Acoustic Doppler Current Estimation Method Based on The Symmiktos Method
- 1995
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Konferensbidrag (refereegranskat)abstract
- The estimation of water current by using acoustic Doppler current meters is a well-known method. Determination of the water current is based on the Doppler shift caused by the movement of small particles in the water, and related to the current as an average. These movements cause a Doppler shift with an assumed Gaussian-shaped distribution in time. Due to scattering from many different bubble sizes and other scatterers, a complex Doppler signal is received with a large variance. The Symmiktos method estimates the first moment of the Doppler signal by using a frequency domain method. This method combines linear and non-linear digital signal processing. The result is a robust and accurate estimation method with a very low bias. In order to verify this performance, a mathematical model of the Doppler shift is used, where effects from different bubble sizes and other reflexes can be taken into account. This mixed statistical model is then used for synthesizing data with different levels of complexity, but with known parameters. These synthesized data makes it possible to quantify the accuracy and performance of different estimation methods such as the Symmiktos method or the Covariance method.
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| 4. |
- Lagö, Thomas L, et al.
(författare)
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The Symmiktos Method : A Robust and Accurate Estimation Method for Acoustic Doppler Current Estimation
- 1993
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Konferensbidrag (refereegranskat)abstract
- Sea current measurements have been of great interest for many years. Mechanical current instruments are still widely used for such applications. Electronic devices, using ultrasound, can measure the current at different depths. The current at different depths, or cells, is directly proportional to the doppler shift in that cell. When the burst or ping is transmitted toward the surface, scattering occurs from entrained air bubbles and other particles in the water. This is the base for the doppler signal and the measurement principle for an acoustic doppler current meter. Due to the variance in the scattering signal, a trade-off between burst length, cell size and measurement time has to be made. Bias in the doppler estimate is often a drawback when trying to decrease the variance. Traditional estimators are based on a Gaussian assumption about the scattered signals distribution, or rather the doppler shift distribution. A robust and accurate estimate of the doppler shift consists of a bias-free estimation of the current with a low variance for various types of data. The Symmiktos method is an estimation method that has improved the accuracy of the doppler calculation, compared to standard methods. This paper contains a description of the background to acoustic doppler current meters, the scattering signal, the traditional assumptions for a doppler estimate, as well as suggestions for the improvement of models for the estimation. An introduction to the Symmiktos method, and the models that are the foundation for this new estimation method is also presented.
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| 5. |
- Lantz, Mikael, et al.
(författare)
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Adjuvant Treatment of Graves' Disease with Diclofenac : Safety, Effects on Ophthalmopathy and Antibody Concentrations
- 2016
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Ingår i: European Thyroid Journal. - : Bioscientifica. - 2235-0640 .- 2235-0802. ; 5:1, s. 6-50
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Orbital morphological changes are often present in patients with Graves' disease (GD) already at diagnosis, and cyclooxygenase type 2 (COX-2) is overexpressed in active Graves' ophthalmopathy (GO).OBJECTIVE: To investigate if adjuvant treatment of GD with the COX inhibitor and peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist diclofenac decreases the development of ophthalmopathy and if laboratory parameters are affected.METHODS: This is a multicenter trial where 61 subjects were randomized to methimazole (block and replace with l-thyroxine) either with or without diclofenac 50 mg 1 × 2 for 12 months. The primary end point development of GO after 24 months was evaluated. Smoking habits were registered and the thyroid parameters TSH, free T4, free T3, TSH receptor antibodies (TRAb) and anti-TPO were followed. Safety parameters (kidney, liver and blood) and adverse events were regularly registered.RESULTS: GO developed in 11% (n = 3) of the patients treated with diclofenac and in 21% (n = 6) of the controls (p = 0.273). The adverse event profile was acceptable without any severe events related to diclofenac. Both TRAb and anti-TPO concentrations decreased during treatment with methimazole, but the anti-TPO concentrations were lower in patients treated with diclofenac after 15 months (p = 0.031). The TRAb concentrations were not significantly changed between groups. Smokers had higher concentrations of TRAb than nonsmokers both at diagnosis of GD (p = 0.048) and after 15 months (p = 0.042).CONCLUSIONS: Treatment with diclofenac had no significant influence on development of GO. Diclofenac reduces anti-TPO concentrations and seems to be safe to use in GD patients.
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| 6. |
- Lantz, Mikael, et al.
(författare)
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Increased TRAb and/or Low Anti-TPO Titers at Diagnosis of Graves' Disease are Associated with an Increased Risk of Developing Ophthalmopathy after Onset.
- 2014
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Ingår i: Experimental and Clinical Endocrinology & Diabetes. - : Georg Thieme Verlag KG. - 1439-3646 .- 0947-7349. ; 122:2, s. 113-117
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Tidskriftsartikel (refereegranskat)abstract
- Patients with low thyroid peroxidase antibodies (anti-TPO) and increased TSH-receptor antibodies (TRAb) at diagnosis of Graves' disease (GD) have been suggested to have an increased risk to develop Graves' ophthalmopathy (GO). The aim was to evaluate if GO development can be predicted.This is an observational study with registration of possible GD and GO risk factors.399 patients with GD were registered 2003-2008 in Malmö, Sweden and out of these 310 were retrospectively followed up to 6 years. The main outcome measures were anti-TPO titer, TRAb titer, smoking habits, radioiodine treatment and GO development.TRAb was assessed with a third generation assay at GD diagnosis in 231 patients. The proportion of patients with GO increased above the median 6.3 IU/L both at diagnosis of GD (p=0.001) and at follow-up (p=0.0001).The distribution of GO patients anti-TPO above or below 20 kIU/L at diagnosis of GD was similar between groups (p=0.239). However at follow-up anti-TPO<20 kIU/L was associated with an increased proportion of newly developed GO as compared to the cohort with anti-TPO>20 kIU/L (p=0.018).87% of patients who developed GO after GD diagnosis had TRAb above 6.3 IU/L and/or anti-TPO below 20 kIU/L. The proportion of GO was doubled in GD patients treated with radioiodine but could not explain the described findingsAnti-TPO<20 kIU/L and/or TRAb>6.3 IE/L at the time of GD diagnosis were associated with an increased risk to develop GO after diagnosis of GD.
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| 7. |
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| 8. |
- Lantz, Mikael, et al.
(författare)
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Thyrostimulin (a TSH-like Hormone) Expression in Orbital and Thyroid Tissue.
- 2007
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Ingår i: Thyroid. - : Mary Ann Liebert Inc. - 1557-9077 .- 1050-7256. ; 17:2, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate gene expression of thyrostimulin in orbital and thyroid tissue from patients with and without Graves' disease. Design: Real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used for detection of thyrostimulin gene expression in intraorbital adipose tissue from patients with severe ophthalmopathy and thyroid healthy controls in addition to thyrostimulin expression in normal thyroid tissue, multinodular goiter tissue, and Graves' thyroid tissue. Main Outcome: In intraorbital tissue, thyrostimulin expression was identified in both patients and controls with fluorescence intensities varying between 0.23 and 0.88 in patients and 0.29 and 8.9 in controls before treatment with DNase. The signal of thyrostimulin was weak or absent in intraorbital adipose tissue from patients with ophthalmopathy and thyroid healthy controls after treatment of samples with DNase. This was in contrast to the expression of the thyroid-stimulating hormone (TSH) receptor and the housekeeping gene cyclophilin A that were detected both before and after DNase treatment. Similar results were found when analyzing human and rat thyroid tissue. Conclusions: Neither did we demonstrate gene expression of thyrostimulin in intraorbital adipose tissue or in thyroid tissue, nor could we confirm earlier findings in rat thyroid tissue. Whether thyrostimulin is a regulator of thyroid function has to be further investigated in future studies.
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| 9. |
- Lindgren, Ola, et al.
(författare)
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The Effect of Radioiodine Treatment on TRAb, Anti-TPO, and Anti-TG in Graves' Disease
- 2019
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Ingår i: European Thyroid Journal. - : Bioscientifica. - 2235-0640 .- 2235-0802. ; 8:2, s. 64-69
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Tidskriftsartikel (refereegranskat)abstract
- Background: In Graves' disease (GD), immunocompetent cells infiltrate thyroid tissue with release of TSH-receptor antibodies (TRAb), and radioiodine treatment is known to elicit an immune response with an increase in TRAb. Objectives: The aim was to study if all patients treated with radioiodine respond with a release of TRAb, anti-thyroperoxidase (anti-TPO), and anti-thyroglobulin (anti-TG). Methods: This is a prospective observational study. GD patients (n = 131) were admitted for treatment with radioiodine. Thyroid antibodies were measured before and 3 months after iodine-131 treatment. Results: After 3 months, a fold change > 1.1 was found in 66% of the GD patients, while the remaining 34% did not have a change or decrease in in TRAb. Anti-TPO and anti-TG also increased; the former showed an increase in 73% and the latter of 52%, while 27 and 48% decreased/were unchanged. A significant positive correlation was found between TRAb and anti-TPO, but not between TRAb and anti-TG. In the group with an increase in TRAb, the median fold change was 5.1, but there were no additional effects of tobacco smoking. The proportion of females below the median age (51.5 years) was significantly higher in the group that increased in TRAb compared to the one that decreased/was unchanged (66 vs. 34%). Conclusions: Treatment with radioiodine elicits an increase in thyroid antibodies, but not in all GD patients. The proportion of responders varied and was affected by age, resulting in a stronger immune response at younger age. However, there were no additional effects of smoking.
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| 10. |
- Planck, Tereza, et al.
(författare)
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COX-2 and SCD, markers of inflammation and adipogenesis, are related to disease activity in Graves' ophthalmopathy
- 2007
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Ingår i: Thyroid. - : Mary Ann Liebert Inc. - 1557-9077 .- 1050-7256. ; 17:6, s. 511-517
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Tidskriftsartikel (refereegranskat)abstract
- Context: Inflammation and adipogenesis are two parallel processes with increased activity in severe Graves' ophthalmopathy. Objective: The aim of this work was to define target genes for therapeutic intervention in adipogenesis and inflammation in Graves' ophthalmopathy. Design: Orbital tissue was obtained from patients with ophthalmopathy in acute or chronic phase undergoing orbital surgery to study gene expression followed by the study of potential intervention mechanisms in preadipocytes. Setting: Clinic of Endocrinology, University Hospital, Malmo, Sweden. Participants: Patients in acute severe or in chronic phase of ophthalmopathy. Interventions: Lateral orbital decompression in acute phase and restorative surgery in chronic phase. In vitro treatment of preadipocytes with rosiglitazone and diclofenac. Main outcome measure: Gene expression in intraorbital tissue or preadipocytes and differentiation of preadipocytes. Results: A marker of adipose tissue, stearoyl-coenzyme A desaturase (SCD), and the proinflammatory gene, cyclooxygenase-2 (COX-2), were overexpressed in patients in active phase compared to the chronic phase of ophthalmopathy. In growth-arrested preadipocytes stimulated with rosiglitazone, COX-2 expression increased temporarily within 1 hour and decreased to undetectable levels after 48 hours. In contrast, SCD and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) expression increased continuously from day 2 to day 7 during adipogenesis. Diclofenac, an inhibitor of cyclooxygenases with antagonistic effects on PPAR-gamma, reduced the number of mature adipocytes by approximately 50%. Conclusion: We conclude that inflammation and adipogenesis decrease with a decrease in activity of ophthalmopathy and that the nonsteroidal antiinflammatory drug diclofenac inhibits adipogenesis. This may represent a putative future treatment of endocrine ophthalmopathy.
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