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Search Results: 1 - 10 of 2784 matches for " Anders Roijer "
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Changes in clot lysis levels of reteplase and streptokinase following continuous wave ultrasound exposure, at ultrasound intensities following attenuation from the skull bone
Bjarne H?rdig, Jonas Carlson, Anders Roijer
BMC Cardiovascular Disorders , 2008, DOI: 10.1186/1471-2261-8-19
Abstract: Clots were made from fresh venous blood drawn from healthy volunteers. Each clot was made from 1.4 ml blood and left to coagulate for 1 hour in a plastic test-tube. The thrombolytic drugs used were, 3600 IU streptokinase (SK) or 0.25 U reteplase (r-PA), which were mixed in 160 ml 0.9% NaCl solution. Continuous-wave US exposure was applied at a frequency of 1 MHz and intensities ranging from 0.0125 to 1.2 W/cm2. For each thrombolytic drug (n = 2, SK and r-PA) and each intensity (n = 9) interventional clots (US-exposed, n = 6) were submerged in thrombolytic solution and exposed to CW-US while control clots (also submerged in thrombolytic solution, n = 6) were left unexposed to US.To evaluate the effect on clot lysis, the haemoglobin (Hb) released from each clot was measured every 20 min for 1 hour (20, 40 and 60 min). The Hb content (mg) released was estimated by spectrophotometry at 540 nm. The difference in effect on clot lysis was expressed as the difference in the amount of Hb released between pairs of US-exposed clots and control clots. Statistical analysis was performed using Wilcoxon's signed rank test.Continuous-wave ultrasound significantly decreased the effects of SK at intensities of 0.9 and 1.2 W/cm2 at all times (P < 0.05). Continuous-wave ultrasound significantly increased the effects of r-PA on clot lysis following 20 min exposure at 0.9 W/cm2 and at 1.2 W/cm2, following 40 min exposure at 0.3, 0.6, 0.9 and at 1.2 W/cm2, and following 60 min of exposure at 0.05 0.3, 0.6, 0.9 and at 1.2 W/cm2 (all P < 0.05).Increasing intensities of CW-US exposure resulted in increased clot lysis of r-PA-treated blood clots, but decreased clot lysis of SK-treated clots.Ultrasound (US) has been used to enhance thrombolytic therapy, for example, in the treatment of stroke. In this setting, US is usually applied over the temporal bone, exposing the obstructed vessel to US concomitantly with treatment with thrombolytic drugs [1-3]. The enhancement of various thrombolytic dru
Manual correction of semi-automatic three-dimensional echocardiography is needed for right ventricular assessment in adults; validation with cardiac magnetic resonance
Ellen Ostenfeld, Marcus Carlsson, Kambiz Shahgaldi, Anders Roijer, Johan Holm
Cardiovascular Ultrasound , 2012, DOI: 10.1186/1476-7120-10-1
Abstract: 62 non-selected patients were examined with 3DE (Sonos 7500 and iE33) and with CMR (1.5T). Endocardial RV contours of 3DE-images were semi-automatically assessed and manually corrected in all patients. End-diastolic (EDV), end-systolic (ESV) volumes, stroke volume (SV) and ejection fraction (EF) were computed.53 patients (85%) had 3DE-images feasible for examination. Correlation coefficients and Bland Altman biases between 3DE with manual correction and CMR were r = 0.78, -22 ± 27 mL for EDV, r = 0.83, -7 ± 16 mL for ESV, r = 0.60, -12 ± 18 mL for SV and r = 0.60, -2 ± 8% for EF (p < 0.001 for all r-values). Without manual correction r-values were 0.77, 0.77, 0.70 and 0.49 for EDV, ESV, SV and EF, respectively (p < 0.001 for all r-values) and biases were larger for EDV, SV and EF (-32 ± 26 mL, -21 ± 15 mL and - 6 ± 9%, p ≤ 0.01 for all) compared to manual correction.Manual correction of the 3DE semi-automatic RV delineation decreases the bias and is needed for acceptable clinical accuracy. 3DE is highly feasible for visualizing the RV in an adult clinical setting.Assessment of the right ventricular volumes and function is of great importance in the diagnosis of various heart diseases e.g. pulmonary hypertension and congenital heart disease [1-3], for the choice of therapeutical strategies [4] and not least of prognostic value [5-7].Two-dimensional echocardiography (2DE) is the most commonly used clinical imaging modality in the evaluation of the right ventricle (RV). The complex geometrical structure of the RV with both a crescent shape and an outspread inflow and outflow tract requires a combination of several different scan planes for estimation of size and function with 2DE. M-Mode and tissue Doppler imaging of the free lateral wall of the RV are measurements in one point and are used as surrogates for the RV function. Hence, current echocardiographic techniques are not suitable for calculating right ventricular volumes and function accurately with a simple algor
Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs
G?ran K Olivecrona, Bjarne H?rdig, Anders Roijer, Mattias Block, Edgars Grins, Hans W Persson, Leif Johansson, Bertil Olsson
BMC Cardiovascular Disorders , 2005, DOI: 10.1186/1471-2261-5-8
Abstract: In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm2 (ISATA) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria.Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 ± 2.0 vs. 4.3 ± 1.5 (mean ± standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 ± 1.7 vs. 6.2 ± 2.0 (p = 0.027).Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified.More then 25 years ago, it was reported that ultrasound (US) may enhance the fibrinolytic process [1]. Throughout the 1980s and 2000s, several in-vitro and in-vivo experiments verified and further explored this effect, using US alone [2] or as a thrombolytic adjuvant [3-13]. The concept has recently been explored in myocardial ischemia [14] and infarction [15] in humans.The physical properties of US fields that may account for the observed profibrinolytic effects include thermal effects, the cavitation effect and micro-streaming [8,11,16,17]. It is, however, still unclear as to how these contribute to the profibrinolytic mechanism. Although these effects of US are beneficial in US enhanced fibrinolysis, they might be harmful to biological tissue in other circumstances, for instance, in already injured tissue. The mechanisms by which US may be potentially harmful to biological tissue are in fact similar to those described in connection with US enhanced fibrinolysis [18-24].The possible net
Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation – the role of atrial cycle length
Carl J Meurling, Anders Roijer, Johan EP Waktare, Fredrik Holmqvist, Carl J Lindholm, Max P Ingemansson, Jonas Carlson, Martin Stridh, Leif S?rnmo, S Bertil Olsson
BMC Cardiovascular Disorders , 2006, DOI: 10.1186/1471-2261-6-11
Abstract: The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF.Dominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion.32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04).In this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.Once atrial fibrillation (AF) has been present for more than a few days, the optimal method for restoring sinus rhythm is DC-cardioversion[1,2]. Unfortunately, only about 25% of the patients remain in sinus rhythm at one year post-cardioversion, with the proportion rising to approximately half of patients if pharmaco
Behavioral involvement and preference for information among male and females with cardiac disease  [PDF]
Ulrica G. Nilsson, Bodil Ivarsson, Carin Alm-Roijer, Petra Svedberg
Open Journal of Nursing (OJN) , 2012, DOI: 10.4236/ojn.2012.22021
Abstract: The aim of this pilot study was to explore and compare preferences for involvement and preferences for information among men and women who had suffered from cardiac disease. A convenience sample of 79 respondents (47 men and 32 women) was recruited from The National Association of Heart and Lung Patients in Sweden at ten local meeting places in different areas. Krantz Health Opinion Survey, KHOS, a 16-item self-rating questionnaire, was used to measure patients’ desire for involvement in healthcare. The results indicate that patients’ information preferences and behavioural preferences are not very high though the total score in KHOS was 5.47. A difference between the genders was also found, seen as higher scores in females than males; 5.93 vs 4.44, p = 0.032, indicating that women prefer a more active role in decision making than men do. The main practical conclusion drawn from this empirical study is that patients are still not as active in seeking information or in behavioural involvement as is desirable.
Cycling as Innovation in Norway and Sweden—A Narrative Study of the Acceptance of a Technical Novelty  [PDF]
Anders Gustavsson
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.21009
Abstract: This paper deals with the acceptance of a technical novelty, in this case cycling, during the late nineteenth and early twentieth century. Experiences and feelings are the focus. The analytical perspectives are: social status, economy, age, gender, work/leisure, safety/danger. The innovation process of cycling conducted by a contrast between two neighbouring countries of Norway and Sweden respectively. The oral source material is found in Norwegian and Swedish folklore archives. The earliest design of bicycle was called velocipede. The bicycles began to appear around 1900. The first owners of bicycles were mostly well-to-do people in both rural and urban areas. As long as there was a shortage of bicycles, a certain collegiality existed, which implied that several people could use the same
Swedish Belief Narratives on Afterlife Earlier and Today  [PDF]
Anders Gustavsson
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.211026
Abstract: My aim is to examine afterlife beliefs in Sweden, partly from the late 1800s and the early 1900s, partly from the 2000s. It will be a contrastive study of two different periods and not a diachronic study of developments across a continuous stretch of time. Since this is a study of popular beliefs, ordinary people are in the center. My research questions are: What types of popular beliefs can be traced in the pre-industrial society? What types of beliefs are characteristic of the present-day society? Which differences and similarities can be found in belief narratives of these periods? How can scholars get information about belief in afterlife in older times and nowadays? In the 1800s this is documented through narratives in folklore archives and inscriptions on grave memorials, nowadays—by means of memorial websites on the Internet.
Psychometric evaluation of a Swedish version of Krantz Health Opinion Survey  [PDF]
Petra Svedberg, Bodil Ivarsson, Ulrica G Nilsson, Asa Roxberg, Amir Baigi, David Brunt, Margareta Brannstrom, Bengt Fridlund, Sylvi Persson, Mikael Rask, Carin Alm-Roijer
Open Journal of Nursing (OJN) , 2012, DOI: 10.4236/ojn.2012.23028
Abstract: The purpose of this study was to evaluate the psychometric properties of a Swedish version of The Krantz Health Opinion Survey (KHOS). A convenience sample of 79 persons (47 men and 32 women) was recruited from The Heart and Lung Patients’ National Association at ten local meeting places in different areas in Sweden. The questionnaire was examined for face and content validity, internal consistency and test-retest reliability. The findings showed that the Swedish version of KHOS is acceptable in terms of face and content validity, internal consistency and test-retest reliability over time among 79 individuals >65 years of age and with a cardiac disease. In conclusion, wider evaluations of the psychometric use of KHOS for other populations and settings are recommended.
Schur Complement Computations in Intel? Math Kernel Library PARDISO  [PDF]
Alexander Kalinkin, Anton Anders, Roman Anders
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.62028
Abstract: This paper describes a method of calculating the Schur complement of a sparse positive definite matrix A. The main idea of this approach is to represent matrix A in the form of an elimination tree using a reordering algorithm like METIS and putting columns/rows for which the Schur complement is needed into the top node of the elimination tree. Any problem with a degenerate part of the initial matrix can be resolved with the help of iterative refinement. The proposed approach is close to the “multifrontal” one which was implemented by Ian Duff and others in 1980s. Schur complement computations described in this paper are available in Intel® Math Kernel Library (Intel® MKL). In this paper we present the algorithm for Schur complement computations, experiments that demonstrate a negligible increase in the number of elements in the factored matrix, and comparison with existing alternatives.
Intel® Math Kernel Library PARDISO* for Intel® Xeon PhiTM Manycore Coprocessor  [PDF]
Alexander Kalinkin, Anton Anders, Roman Anders
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.68121
Abstract: The paper describes an efficient direct method to solve an equation Ax = b, where A is a sparse matrix, on the Intel® Xeon PhiTM coprocessor. The main challenge for such a system is how to engage all available threads (about 240) and how to reduce OpenMP* synchronization overhead, which is very expensive for hundreds of threads. The method consists of decomposing A into a product of lower-triangular, diagonal, and upper triangular matrices followed by solves of the resulting three subsystems. The main idea is based on the hybrid parallel algorithm used in the Intel® Math Kernel Library Parallel Direct Sparse Solver for Clusters [1]. Our implementation exploits a static scheduling algorithm during the factorization step to reduce OpenMP synchronization overhead. To effectively engage all available threads, a three-level approach of parallelization is used. Furthermore, we demonstrate that our implementation can perform up to 100 times better on factorization step and up to 65 times better in terms of overall performance on the 240 threads of the Intel® Xeon PhiTM coprocessor.
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