| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Charisopoulou, Dafni, et al.
(författare)
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Exercise Induced Worsening of Mechanical Heterogeneity and Diastolic Impairment in Long QT Syndrome
- 2021
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Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 10:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Electromechanical heterogeneities due to marked dispersion of ventricular repolarisation and mechanical function have been associated with symptoms in long QT syndrome (LQTS) patients.Aim: To examine the exercise response of longitudinal LV systolic and diastolic myocardial function and synchronicity in LQTS patients and its relationship with symptoms; Methods: Forty seven (age 45 ± 15 yrs, 25 female, 20 symptomatic) LQTS patients and 35 healthy individuals underwent an exercise test (Bruce protocol). ECG and echo parameters were recorded at rest, peak exercise (p.e.), and recovery.Results: LQTS patients had prolonged and markedly dispersed myocardial contraction, delayed early relaxation phase, and significantly decreased filling time at all exercise phases. Unlike controls, these electromechanical disturbances deteriorated further with exercise, during which additional decrease of the LV diastolic myocardial function and attenuated LV stroke volume were noted. Such abnormal responses to exercise were seen to a greater degree in symptomatic patients and in the LQT1 subgroup and improved with B-blocker therapy. Worsening myocardial contraction dispersion at p.e. was the strongest discriminator for previous clinical events, and its discriminating power excelled further by adding early relaxation delay.Conclusions: Electromechanical disturbances were shown to worsen during exercise in LQTS patients and were more pronounced in those with previous arrhythmic events.
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| 3. |
- Forsblad-D’Elia, Helena, et al.
(författare)
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Biomechanical properties of common carotid arteries assessed by circumferential 2D strain and β stiffness index in patients with ankylosing spondylitis
- 2021
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Ingår i: Journal of Rheumatology. - 0315-162X. ; 48:3, s. 352-360
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Ankylosing spondylitis (AS) is associated with an elevated risk of cardiovascular disease (CVD) related to atherosclerosis, preceded by arterial stiffness. We aimed to examine common carotid artery (CCA) biomechanical properties using ultrasound to calculate β stiffness index (indicating arterial stiffness) and, a more recently developed technique, 2-dimensional (2D) speckle tracking strain (indicating arterial motion and deformation, strain) to (1) compare with age- and sex-matched controls, and (2) analyze relationships between strain and stiffness with disease characteristics and traditional risk factors for CVD in patients with AS. Methods. In this cross-sectional study, a cohort of 149 patients with AS, mean age 55.3 ± 11.2 years, 102 (68.5%) men, and 146 (98%) HLA-B27–positive, were examined. Bilateral CCA were examined for circumferential 2D strain and β stiffness index. A subgroup of 46 patients was compared with 46 age- and sex-matched controls, both groups without hypertensive disease, diabetes, myocardial infarction, or stroke. Results. Mean bilateral circumferential 2D strain was lower in AS patients compared with controls (7.9 ± 2.6% vs 10.3 ± 1.9%, P < 0.001), whereas mean bilateral β stiffness index was higher (13.1 ± 1.7 mmHg/mm vs 12.3 ± 1.3 mmHg/mm, P = 0.02). In multivariable linear regression analyses, strain was associated with age, erythrocyte sedimentation rate, history of anterior uveitis, and treatment with conventional synthetic disease-modifying antirheumatic drugs (DMARD) and/or biological DMARD (R2 0.33), while stiffness was associated with age (R2 0.19). Conclusion. Both CCA circumferential 2D strain and β stiffness index differed between patients with AS and controls. Strain was associated with AS-related factors and age, whereas only age was associated with stiffness, suggesting that the obtained results reflect different pathogenic vascular processes.
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| 4. |
- Forsblad-d'Elia, Helena, et al.
(författare)
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Biomechanical properties of common carotid arteries assessed by circumferential two-dimensional strain and β stiffness index in patients with ankylosing spondylitis
- 2021
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Ingår i: Journal of Rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 48:3, s. 352-360
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Ankylosing spondylitis (AS) is associated with an elevated risk of cardiovascular disease (CVD) related to atherosclerosis, preceded by arterial stiffness. We aimed to examine common carotid artery (CCA) biomechanical properties using ultrasound to calculate β stiffness index (indicating arterial stiffness) and, a more recently developed technique, two-dimensional (2D) speckle tracking strain (indicating arterial motion and deformation, strain) to 1) compare with age- and sex-matched controls and to 2) analyze relationships between strain and stiffness with disease characteristics and traditional risk factors for CVD in AS patients.METHODS: In this cross-sectional study, a cohort of 149 patients with AS, mean age 55.3±11.2 years, 102(68.5%) men, 146 (98%) HLA-B27 positive, were examined. Bilateral CCAs were examined for circumferential 2D strain and β stiffness index. A subgroup of 46 patients were compared with 46 age- and sex-matched controls, both groups without hypertensive disease, diabetes, myocardial infarction or stroke.RESULTS: Mean bilateral circumferential 2D strain was lower in AS patients compared with controls, 7.9±2.6% vs 10.3±1.9%, p<0.001 whereas mean bilateral β stiffness index was higher, 13.1±1.6mmHg/mm vs 12.3±1.3mmHg/mm, p=0.018. In multivariable linear regression analyses strain was associated with age, erythrocyte sedimentation rate, history of anterior uveitis and treatment with csDMARD and/or bDMARD (R2 0.33), while stiffness was associated with age (R2 0.19).CONCLUSION: Both CCA circumferential 2D strain and β stiffness index differed between AS patients and controls. Strain was associated with AS-related factors and age while stiffness with age, suggesting that the obtained results reflect different pathogenic vascular processes.
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| 5. |
- Forsblad-d'Elia, Helena, et al.
(författare)
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Educed strain and increased stiffness of common carotid arteries in patients with ankylogin spondylitis
- 2019
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ Publishing Group Ltd. - 0003-4967 .- 1468-2060. ; 78, s. 1241-1241
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Ankylosing spondylitis (AS) is associated with an increased risk of cardiovascular disease (CVD) which also contributes to the increased mortality observed in AS. It is therefore important to develop non-invasive, accurate methods for early detection of atherosclerotic vascular changes. Studies, in other populations, have demonstrated associations between arterial stiffness and atherosclerotic burden and incident cardiovascular events. The arterial stiffness can be examined by ultrasound providing the β stiffness index that evaluates mechanical deformation properties. Technological advancements in ultrasound have developed a method assessing strain, using speckle tracking technique, which measures deformation mechanics in more dimensions. The speckle tracking method assessing arterial wall motion might permit earlier detection of subclinical CVD.Objectives: To study, for the first time, bilateral common carotid arterial (CCA) circumferential strain and β stiffness index in patients with AS and 1) compare the results with age and sex-matched controls and 2) explore relationships between circumferential strain and β stiffness index with disease activity, physical function and traditional risk factors for CVD in patients with AS.Methods: A cohort of 149 patients with AS from Northern Sweden (Modif NY, mean age 55.3±11.2 years, 102(68.5%) men, 146(98%) HLAB27) were assessed with spinal radiographs for mSASSS, clinical examination and BASMI, BASFI, ASDAS-CRP and BASDAI. Forty-six patients with AS (50.4±8.7 years, 31(67%) men) and 46 age- and sex-matched controls (49.8±9.2 years, 31(67%) men) with no known hypertension, diabetes or previous CV events were compared. Bilateral CCA ultrasound was carried out on all patients and controls. The circumferential systolic strain was measured and the β stiffness index was calculated. To analyze factors associated with strain and β stiffness index univariate and standard multivariable linear regression analyses were used. Variables with a univariate p-value ≤ 0.1 were considered for the multivariable models. For dichotomous variables, yes was coded 1 and no was coded 0.Results: The mean strain was significantly lower in AS patients compared with controls, 7.9±2.6% vs 10.3±1.9%, p<0.001 and the mean β stiffness index was significantly higher in AS compared to controls, 13.1±1.6 mmHg/mm vs 12.3±1.3 mmHg/mm, p=0.018.
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| 6. |
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| 7. |
- Gottfridsson, Peter, et al.
(författare)
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Global longitudinal strain: effects by load and autonomic nervous system expression
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: Intrathoracic pressure related to breathing or positive pressure ventilatory support has effects on venous return to the heart and transmyocardial pressures. In addition, autonomic nerve system activity affects cardiac inotropy, chronotropy, and loading. Knowledge of these physiological interactions is relevant when interpreting atrial and ventricular strain results as part of heart function assessment by echocardiography in patients with ventilatory support. Purpose: We aimed to assess 2-D global longitudinal strain (GLS%) for all four heart chambers (atria and ventricles) during controlled changes in intrathoracic pressure, as well as sympathetic nerve system activation. We hypothesized that GLS% is affected by both load and sympathetic tone. Methods: With ethical approval and participant consent, 20 healthy volunteers (medical students) performed a controlled Valsalva manoeuvre, a mask positive pressure inspiration (CPAP) manoeuvre (25 cm H2O) and a Hand Grip manoeuvre (squeezing a rolled towel with 75% of maximum force with one hand for 2 minutes). We monitored continuous blood pressure and heart rate (using a Finapres) during the manoeuvres to make sure that the manoeuvres caused the desired physiologic effects.GLS% of the individual chambers were measured before and during these manoeuvres using commercially available post- processing software, from the 4-chamber view. 2 different operators measured independently the GLS% for every manoeuvre. Paired measurement comparisons were performed (paired t test). Results: Both the Valsalva maneuverer and CPAP caused reductions in GLS % in all four chambers. The Hand Grip manoeuvre did not cause any change in GLS % in any chamber.Conclusion: Since both CPAP and late Valsalva causes a reduction in preload, we assume that a decrease in preload causes a reduction in GLS% in the heart chambers. Both Valsalva and Handgrip manoeuvres causes a raised sympathicus tone which does not seem to affect GLS% in any chamber. (In the Hand Grip manoeuvre there was a rise in blood pressure and pulse during the manoeuvre, as a sign of increased sympathetic tone.)From these preliminary findings, we conclude that for healthy young individuals GLS% appears to decrease in all chambers during Valsalva and CPAP, while no change in GLS% is caused by the Hand Grip manoeuvre.
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| 8. |
- Gottfridsson, Peter, et al.
(författare)
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Left atrial contraction strain and controlled preload alterations, a study in healthy individuals
- 2022
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Ingår i: Cardiovascular Ultrasound. - : BioMed Central. - 1476-7120. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In order to assess left atrial contractile function in disturbed circulatory conditions, it is necessary to have a clear understanding of how it behaves in a normal resting state with changes in loading conditions. However, currently the understanding of this relationship is incomplete. We hypothesize that in healthy individuals, left atrial contraction strain and its peak strain rate are increased or decreased by increasing or decreasing preload, respectively.METHODS: Controlled maneuvers used to change preload included continuous positive airway pressure by mask (CPAP 20 cmH2O) for preload decrease, and passive leg raise (15 degrees angle) for preload increase. Cardiac ultrasound 4-chamber views of the left atria and left ventricle were acquired at baseline and during maneuver. Acquired images were post processed and analyzed offline. Comparisons were made using paired t-test and means with 95% confidence interval.RESULTS: There were 38 participants, complete results were obtained from 23 in the CPAP maneuver and 27 in the passive leg raise maneuver. For the CPAP group, left atrial contraction strain was 11.6% (10.1 to 13.1) at baseline and 12.8% (11.0 to 14.6) during the maneuver (p = 0.16). Left atrial contraction peak strain rate was - 1.7 s- 1 (- 1.8 to - 1.5) at baseline and - 1.8 s- 1 (- 2.0 to - 1.6) during the maneuver (p = 0.29). For the passive leg raise-group, left atrial contraction strain was 10.1% (9.0 to 11.2) at baseline and 10.8% (9.4 to 12.3) during the maneuver (p = 0.28). Left atrial contraction peak strain rate was - 1.5 s- 1 (- 1.6 to - 1.4) at baseline and - 1.6 s- 1 (- 1.8 to - 1.5) during the maneuver (p = 0.29). Left atrial area, an indicator of preload, increased significantly during passive leg raise and decreased during CPAP.CONCLUSION: In healthy individuals, left atrial contraction strain and its peak strain rate seem to be preload-independent.TRIAL REGISTRATION: The study was 2018-02-19 registered at clinicaltrials.gov ( NCT03436030 ).
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| 9. |
- Gottfridsson, Peter, et al.
(författare)
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Left atrial contraction strain during a Valsalva manoeuvre : A study in healthy humans
- 2023
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Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 43:3, s. 165-169
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac mechanics are influenced by loading conditions as well as sympathetic tone. Left atrial (LA) contractile function assessed by two-dimensional (2D) strain has been described in the setting of controlled preload alterations; however, studies show conflicting findings about change or direction of change. We hypothesized that the controlled preload reduction and the sympathetic nervous system activation that occurs during a standardized Valsalva manoeuvre would bring about a change in LA contraction strain.aMETHODS: Healthy young adults of both sexes were recruited. Transthoracic echocardiographic ultrasound images were collected before and during a Valsalva manoeuvre. Standard imaging windows for LA strain assessment were used and the images were copied and stored for later offline analysis. These were assessed for adequate atrial wall visualization in 2D strain assessment. Paired comparisons were carried out using Student's T test.RESULT: Thirty-eight participants were included and there were 22 complete studies with paired pre- and during Valsalva manoeuvre. LA contraction strain at baseline was 10.5 ± 2.8% (standard deviation) and during the Valsalva manoeuvre 10.6 ± 4.6%, p = 0.86.CONCLUSION: The Valsalva manoeuvre, a combination of preload reduction and sympathetic nervous system activation, seems not to be associated with a change in LA contraction strain in healthy young individuals. LA contraction strain should be interpreted in the context of both atrial loading conditions and prevailing autonomic nervous system activity.
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| 10. |
- Hulander, Erik, et al.
(författare)
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Patients with radiographic axial spondylarthritis have an impaired dietary intake-a cross-sectional study with matched controls from northern Sweden.
- 2023
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Ingår i: Arthritis research & therapy. - : BioMed Central (BMC). - 1478-6362 .- 1478-6354. ; 25:1
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Tidskriftsartikel (refereegranskat)abstract
- Radiographic axial spondyloarthritis (r-axSpA) is one of the most common chronic inflammatory rheumatic diseases, affecting about 0.2% of the Swedish population. Adequate nutritional intake is essential for maintaining physiological functions. A poor diet increases the risk of developing conditions such as obesity, osteoporosis, and/or atherosclerosis. Diet quality is also theorized to affect systemic inflammation. Dietary habits in patients with r-axSpA are largely unknown. The aims of this study were to assess dietary nutrient intake in r-axSpA patients and examine whether it differs compared to persons without r-axSpA.r-axSpA patients (modified NY criteria) at the rheumatology clinic in Region Västerbotten, northern Sweden, were invited to take part in the Backbone study which investigates disease severity and comorbidities. In total, 155 patients were included. Nutritional intake was assessed by the semi-quantitative food frequency questionnaire MiniMeal-Q. Controls were collected from the Swedish CArdioPulmonary bioImage Study (n=30,154), a study that invited participants 50-64years of age by random selection from the Swedish population register. Out of the 155 r-axSpA patients, 81 were in the same age span. Four controls were identified for each patient, matched on age (±1year), sex, and geographic location. Data on dietary intake was available for 319 controls. Statistical comparisons of dietary intake between patients with r-axSpA and controls were done by exact conditional logistic regression analysis, adjusted for country of birth, educational level, single household, weight, smoking status, and energy intake.Patients had a comparatively significantly higher energy intake from carbohydrates, a lower fiber density, and a lower intake of marine omega-3 fatty acids. Furthermore, intake of vitamins D, E, and K as well as selenium, folate, calcium, magnesium, phosphorus, potassium, vitamin A, and β-carotene (a precursor of vitamin A and marker of vegetable and fruit intake) was significantly lower among patients compared to controls.Our results suggest that r-axSpA patients have an impaired dietary intake. Notably, intake was lower in several nutrients theorized to have anti-inflammatory properties (fiber density, marine-omega-3 fatty acids, vitamin D, and selenium). We further propose that nutrition screening might be incorporated into the management of r-axSpA patients.
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