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  • 201. Karltun, Anette
    et al.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Engkvist, Inga-Lill
    Lindbeck, Lars
    Developing a systems view of butchers' problematic work situation2008Conference paper (Other academic)
  • 202.
    Karltun, Johan
    et al.
    Jönköpings Tekniska Högskola.
    Vogel, Kjerstin
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Bergstrand, M.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Maintaining knife sharpness in industrial meat cutting: A matter of knife or meat cutter abilityManuscript (preprint) (Other academic)
  • 203. Kirbis, M.
    et al.
    Morrison, S.
    Rojc, B.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Igor, M.
    Groselj, L. Dolenc
    Hypoxia and bedrest progressively attenuate parasympathetic activity during sleep2016In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 25, p. 236-237Article in journal (Other academic)
  • 204.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Biomechanics of sports head injury and helmet design2011Conference paper (Other academic)
  • 205.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Cycle helmets2011In: IOC World Conference on Prevention of Injury & Illness in Sports: Sports helmets now and in the future, 2011Conference paper (Other academic)
  • 206.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Finite Element Modeling of the Human Head2000Licentiate thesis, comprehensive summary (Other academic)
  • 207.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Finite Element Modeling of the Human Head: A Review1998Report (Other academic)
  • 208.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Förståelse för biomekaniken bakom traumatiska skallskador genom finit element modellering av det mänskliga huvudet2007Conference paper (Other academic)
  • 209.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Förståelsen för biomekaniken bakom traumatiska skallskador genom finit elementmodelleing av det mänskliga huvudet2005Conference paper (Other academic)
  • 210.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Influence of Anatomical Features and Modelling Strategies in Traumatic Brain Injury Prediction2010Conference paper (Other academic)
  • 211.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Influence of Anatomical Features and Modelling Strategies in Traumatic Brain Injury Prediction2010Conference paper (Other academic)
  • 212.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Mathematical models used in TBI2010Conference paper (Other academic)
    Abstract [en]

    In Sweden, head injuries causes about 78% of the deaths in motor vehicle accidents. The total annual rate of head injuries in Sweden over the last 14 years is also relatively constant. Thus, in spite of several national preventive strategies, there has not been an important impact on the total burden of head injury. Neurotrauma is the physical damage that results when the human skull and brain are suddenly subjected to intolerable levels of energy that is usually transmitted mechanically. Most of the research in the injury prevention area was initiated by the military aircraft industry in the sixties and seventies. Today the research is to a greater extent sponsored by the car manufacturing industry, partly as a result of the demands from the customers and the media. However, there is a long way to go before a complete understanding of the pathophysiological events following an accident is reached. This paper primarily focuses on summarizing current efforts, and to outline future strategies in human head injury modeling. Although the finite element (FE) modeling of the human head has been advancing over the past decades, it is still far from being able to explain all brain injury mechanisms and predict all types of impact injuries. However, using proper material characterization, correct boundary conditions and detailed geometric representation, a finite element model of the human head can provide us a powerful tool. A detailed and parameterized FE model of the adult human head is presented. It includes the scalp, skull, brain, meninges, cerebrospinal fluid (CSF), and eleven pairs of bridging veins. Separate representations of gray and white matter, and inclusion of the ventricles were also implemented. Non-linear and viscoelastic models are derived for the central nervous system (CNS) and meninges and the importance for injury prediction is outlined. The fluids were modelled using an Eulerian FE formulation, and constrains between fluids and solids were defined. Proposed injury measures for the CNS are also evaluated. Application of the FE head model to reconstructions of real head injury cases will also be discussed.

  • 213.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Ny diagnostisk bildmetod för analys av händelseförloppet2007Conference paper (Other academic)
  • 214.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    The biomechanics of ‘real’ head protection: New thoughts on preventing TBI2008Conference paper (Other academic)
  • 215.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Utvärdering av skadepotentialen för “Flexible Baton1999Report (Other academic)
  • 216.
    Kleiven, Svein
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Johnson, Ho
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Sandler, Håkan
    Rättsmedicinalverket, Uppsala universitet.
    Finite Element Methodology and infant skull fracture: accident or abuse ?2009Conference paper (Other academic)
  • 217.
    Kleiven, Svein
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Evaluation of Head Injury Criteria2002Report (Other academic)
  • 218.
    Kothapalli, Satya V.V.N.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Nano-Engineered Contrast Agents: Toward Multimodal Imaging and Acoustophoresis2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Diagnostic ultrasound (US) is safer, quicker and cheaper than other diagnostic imaging modalities. Over the past two decades, the applications of US imaging has been widened due to the development of injectable, compressible and encapsulated microbubbles (MBs) that provide an opportunity to improve conventional echocardiographic imaging, blood flow assessment and molecular imaging. The encapsulating material is manufactured by different biocompatible materials such as proteins, lipids or polymers. In current research, researchers modify the encapsulated shell with the help of advanced molecular chemistry techniques to load them with dyes (for fluorescent imaging), nanoparticles and radioisotopes (for multimodal imaging) or functional ligands or therapeutic gases (for local drug delivery). The echogenicity and the radial oscillation of MBs is the result of their compressibility, which undoubtedly varies with the encapsulated shell characteristics such as rigidity or elasticity.

    In this thesis, we present acoustic properties of novel type of polyvinyl alcohol (PVA)-shelled microbubble (PVA-MB) that was further modified with superparamagnetic iron oxide nanoparticles (SPIONs) to work as a dual-modal contrast agent for magnetic resonance (MR) imaging along with US imaging. Apparently, the shell modification changes their mechanical characteristics, which affects their acoustic properties. The overall objective of the thesis is to investigate the acoustic properties of modified and unmodified PVA-MBs at different ultrasound parameters.

    The acoustic and mechanical characterization of SPIONs modified PVA-MBs revealed that the acoustical response depends on the SPION inclusion strategy. However they retain the same structural characteristics after the modification. The modified MBs with SPIONs included on the surface of the PVA shell exhibit a soft-shelled behavior and produce a higher echogenicity than the MBs with the SPIONs inside the PVA shell. The fracturing mechanism of the unmodified PVA-MBs was identified to be different from the other fracturing mechanisms of conventional MBs. With the interaction of high-pressure bursts, the air gas core is squeezed out through small punctures in the PVA shell. During the fracturing, the PVA-MBs exhibit asymmetric (other modes) oscillations, resulting in sub- and ultra-harmonic generation. Exploiting the US imaging at the other modes of the oscillation of the PVA-MBs would provide an opportunity to visualize very low concentrations of (down to single) PVA-MBs. We further introduced the PVA-MBs along with particles mimicking red blood cells in an acoustic standing-wave field to observe the acoustic radiation force effect. We observed that the compressible PVA-MBs drawn toward pressure antinode while the solid blood phantoms moved toward the pressure node. This acoustic separation method (acoustophoresis) could be an efficient tool for studying the bioclearance of the PVA-MBs in the body, either by collecting blood samples (in-vitro) or by using the extracorporeal medical procedure (ex-vivo) at different organs.

    Overall, this work contributes significant feedback for chemists (to optimize the nanoparticle inclusion) and imaging groups (to develop new imaging sequences), and the positive findings pave new paths and provide triggers to engage in further research. 

  • 219.
    Kothapalli, Satya V.V.N.
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Wiklund, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
    Janerot Sjöberg, Birgitta
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet, Sweden; Karolinska University Hospital, Sweden .
    Paradossi, Gaio
    Diapartimento di Chimica, Università di Roma Tor Vergata.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet, Sweden; Karolinska University Hospital, Sweden .
    Investigation of Polymer-Shelled Microbubble Motions in AcoustophoresisManuscript (preprint) (Other academic)
    Abstract [en]

    The objective of this paper is to explore the trajectory motion of microsize (typically smaller than a redblood cell) encapsulated polymer-shelled gas bubbles propelled by radiation force in an acousticstanding-wave field and to compare the corresponding movements of solid polymer microbeads. Theexperimental setup consists of a microfluidic chip coupled to a piezoelectric crystal (PZT) with aresonance frequency of about 2.8 MHz. The microfluidic channel consists of a rectangular chamberwith a width, w, corresponding to one wavelength of the ultrasound standing wave. It creates one fullwave ultrasound of a standing-wave pattern with two pressure nodes at4w and43w and threeantinodes at 0,2w , and w. The peak-to-peak amplitude of the electrical potential over the PZT wasvaried between 1 and 10 volts. From Gor’kov’s potential equation, the acoustic contrast factor, Φ, forthe polymer-shelled microbubbles was calculated to about -60.7. Experimental results demonstratethat the polymer-shelled microbubbles are translated and accumulated at the pressure antinode planes.This trajectory motion of polymer-shelled microbubbles toward the pressure antinode plane is similarto what has been described for other acoustic contrast particles with a negative Φ. First, primaryradiation forces dragged the polymer-shelled microbubbles into proximity with each other at thepressure antinode planes. Then, secondary radiation forces caused them to aggregate at different spotsalong the channel. The relocation time for polymer-shelled microbubbles was 40 times shorter thanthat for polymer microbeads, and in contrast to polymer microbeads, the polymer-shelledmicrobubbles were actuated even at driving voltages (proportional to radiation forces) as low as 1 volt.In short, the polymer-shelled microbubbles demonstrate the behavior attributed to the negativeacoustic contrast factor particles and thus can be trapped at the antinode plane and thereby seperatedfrom solid particles, such as cells. This phenomenon could be utilized in exploring future applications,such as bioassay, bioaffinity, and cell interaction studies in vitro in a well-controlled environment.

  • 220.
    Kothapalli, Veera Venkata Satya Naray
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Faridi, Asim
    Wiklund, Martin
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet (KI), CLINTEC – Division of Medical Imaging and Technology.
    On-chip actuation of polymer shelled microbubbles2013Conference paper (Other academic)
  • 221.
    Kothapalli, Veeravenkata S.
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Oddo, L.
    Paradossi, G.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Assessment of the viscoelastic and oscillation properties of a nanoengineered-shelled multimodality contrast agentManuscript (preprint) (Other academic)
  • 222.
    Kothapalli, VeeraVenkata Satyanarayana
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Ultrasound Contrast Agents Loaded with Magnetic Nanoparticles: Acoustic and Mechanical Characterization2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The current methodologies in body scanning diagnostic uses different simultaneous imaging modalities like Ultrasound (US), magnetic resonance imaging (MRI), single photon emission tomography (SPECT) and positron emission tomography (PET). The field requires combination of different modalities for effective use in clinical diagnostics. Such incorporation of different modalities has already been achieved. For example, PET-CT hybrid scanner is designed to acquire align functional and anatomical images and recently US-MRI scanner has successfully shown to improve diagnosis of prostate cancer. The non ionizing radiation hybrid US-MRI is of great interest in health care industry. Further these US and MRI modalities uses different contrast agents like micro-sized gas bubbles (MBs) encapsulated by surfactant for US and superparamagnetic nanoparticles for MRI imaging modalities to further enables new diagnostic opportunities and therapeutic applications. Recently in our 3MiCRON project, we have developed the multimodal contrast agent that could be supported for both US and MRI. This was achieved by coating the magnetic nanoparticles to the poly vinyl alcohol (PVA) surfactant shelled MBs. The nanoparticles in the shell effect the structure can alter the MBs performance as an ultrasound contrast agent. The present thesis is conducted to examine the acoustic and mechanical properties of such multimodal contrast agents.

    These multimodal contrast agents were prepared by coating the surface of PVA-shelled MBs by two following strategies: (1) The superparamagnetic iron oxide (Fe3O4) nano-particles (SPIONs) were chemically anchored to the surface of poly vinyl alcohol (PVA) shelled MBs namely MBs-chem and (2) in the second strategy the SPIONs were physical entrapped into the PVA shell while formation of PVA surface on the gas bubble were named as MBs-phys. To understand the scattering efficiency and viscoelastic properties of these modified agents, we investigated the backscattering power, attenuation coefficient and phase velocity measurements. Our acoustic experimental results indicate that both the modified MBs and non-modified plain PVA-shelled ultrasound contrast agents have the same echogenic response. The investigation of mechanical properties of modified MBs revealed that the attached SPIONs on the PVA shell has reduced the stiffness of MBs-chem shell, while, the SPIONs inside the shell has increased MBs-phys stiffness. As a result, MBs-chem exhibits soft shell behavior under ultrasound exposure than both MBs-phys. Finally, the images were obtained through the MRI investigations at the department of Radiology, Karolinksa Institute, has demonstrated that both MB types have enough magnetic susceptibility that further provides good detectability in vitro and in vivo. As an outlook, the modified magnetic gas bubbles, i.e. both MBs-chem and MBs-phys can be proposed as a potential contrast agent for both US and MR imaging and can be further utilized in potential therapeutic applications.

  • 223.
    Kronander, Håkan
    KTH, School of Technology and Health (STH), Medical Engineering.
    Diagnostic and Prognostic Value of Exercise Electrocardiographic Test Variables in Coronary Artery Disease2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The diagnostic performance of conventional analysis of the exercise electrocardiographic (ECG) test for the detection of coronary artery disease (CAD) is limited to 70-75%. The exercise ECG test is the most widely used non-invasive method for assessing CAD and even a small improvement in the diagnostic performance is important. The objective of this thesis was to investigate the diagnostic performance of the exercise ECG test for diagnosis of CAD and the prognostic performance of the test for predicting acute myocardial infarction (AMI), in both men and women.

    In the diagnostic part of the present study, aimed at finding the optimal diagnostic information during the exercise and recovery phase, 1,877 electrocardiograms selected from 8,322 consecutive patients undergoing a routine exercise test on bicycle ergometer were evaluated. CAD was verified angiographically in 669 patients and excluded in 1,208 patients, by angiography (119 patients), by myocardial scintigraphy (250 patients), or on clinical grounds (839 patients).

    The diagnostic performance of ST-segment amplitude, and the difference between heart rate (HR) matched recovery and exercise ST-segment amplitudes (ST/HR difference), were evaluated by constructing receiver operating characteristic (ROC) curves for each sample point every 12th second during 10 minutes of recovery as well as the last 4 minutes of exercise for the ST-segment amplitude. ST-segment amplitude performed better after exercise than during exercise and best within the first 2 minutes of recovery. Its diagnostic ability did not differ from the ST/HR difference. Both methods performed better in men than in women and the diagnostic information appeared mainly in leads I, -aVR, II, V4, V5 and V6.

    The effect of different sampling rates (1, 2 and 5 samples/min) on the CAD discrimination ability of ST/HR loop area was evaluated by using ROC curves. A use of sampling frequency below 2 samples/min resulted in a significantly diminished diagnostic performance.

    ST-segment and ST/HR variables were compared during exercise and during early post-exercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Discriminating capacity of the methods was evaluated by the use of ROC areas. Partition values, providing the combination of the best sensitivity and specificity, were established. The results demonstrate that analysis of post-exercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD.

    The prognostic part of the study included 8,317 of the 8,322 patients and covered a mean follow-up period of 9.5 years. This part of the study was used to evaluate the long-term prognostic value of ST/HR hysteresis in predicting AMI and all-cause mortality in men and women. ST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.

  • 224.
    Kronander, Håkan
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Fischer-Colbrie, W
    Hammar, N.
    Nowak, J.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Elmqvist, Håkan
    Analysis of ST/HR hysterisis improves long-term prognostic value of exercise ECG test.Manuscript (preprint) (Other academic)
  • 225.
    Kuang, Qie
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Structural studies of membrane proteins using transmission electron microscopy2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Membrane proteins play important roles for living cells. They control transportation of ions, solutes, and nutrients across the membrane and catalyze metabolic reactions. Transmission electron microscopy has its advantages in convenient sample preparation, straightforward structural determination, and wide applications for diverse specimens. In this thesis, the structure of three membrane proteins are studied by this method.

    Kch, a potassium channel in Escherichia coli, has a transmembrane part and a cytosolic domain. Large and well-ordered two dimensional crystals were obtained from both a functional mutant (KchM240L) and a modified protein possessing only the transmembrane part (KchTM). Both samples crystallize as two symmetry-related overlapping layers. Furthermore, the KchTM structure was reconstructed which showed that the transmembrane part of the two adjacent proteins are involved in forming the crystal contacts. Thus, the cytosolic domains of Kch in crystals are deduced to expose to the solvent and do not interact with each other.

    MGST1 (microsomal glutathione transferase 1) is a detoxification enzyme. It was recombinantly over-expressed in the current study, instead of purified from rat liver as before. The crystallization condition was adjusted and isomorphic crystals were obtained. The refined model was built from a combined data set consisting of previous and new diffraction patterns. More residues at the C-terminus of the transmembrane helix 1 were assigned and the residues in the transmembrane helices 3 and 4 were remodeled. Several phospholipid molecules were observed and the ligand glutathione adopts an extended conformation in the refined model.

    The structure of MelB (a sugar/sodium symporter in Escherichia coli) was determined using a refined single particle reconstruction method. This novel method is aimed for processing small or locally distorted crystals. In comparison with the previously published single particle reconstruction protocol, the current method is improved in several aspects. A more reliable reconstruction of MelB was obtained and the resolution was increased. The docking experiment indicates that MelB adopts an open conformation under the present two dimensional crystallization condition.

    Electron microscopy has developed quickly recently with the help of modern instruments, techniques, and software. This method will without doubt play a more critical role in future structural biology.

     

  • 226.
    Kuang, Qie
    et al.
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology. Karolinska Institutet, Sweden.
    Purhonen, Pasi
    Ålander, Johan
    Svensson, Richard
    Hoogland, Veronika
    Winerdal, Jens
    Spahiu, Linda
    Ottosson-Wadlund, Astrid
    Armstrong, Richard
    Jegerschöld, Caroline
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Morgenstern, Ralf
    Hebert, Hans
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    A refined atomic model for microsomal glutathione transferase 1 from electron crystallographyManuscript (preprint) (Other academic)
    Abstract [en]

    Microsomal glutathione transferase 1 (MGST1) is a detoxification enzyme belonging to the Membrane Associated Proteins in Eicosanoid and Glutathione Metabolism (MAPEG) superfamily. Here we have used electron crystallography of two-dimensional (2D) crystals in order to determine an atomic model of rat MGST1 in a lipid environment. The 2D crystals were of the p6 two-sided plane group symmetry. For the refinement, information to 3.5 Å resolution from 225 electron diffraction patterns recorded from specimens at tilt angles up to 66° was used. The model comprises 123 of the 155 amino acid residues, two structured phospholipid molecules, two hydrocarbon chains, and one glutathione (GSH) molecule. Interactions between subunits form trimers centered on the crystallographic three-fold axes of the unit cell. The GSH substrate binds in an extended conformation at the interface between two subunits of the trimer. The location of GSH is supported by mutagenesis data in vitro.

  • 227. Kumar, Ramakrishnan B.
    et al.
    Hebert, Hans
    KTH, School of Technology and Health (STH), Structural Biotechnology.
    Jegerschold, Caroline
    Deciphering the Interaction of FLAP and 5LO2013In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 104, no 2, p. 540A-540AArticle in journal (Other academic)
  • 228.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Distensibility in Arteries, Arterioles and Veins in Humans: Adaptation to Intermittent or Prolonged Change in Regional Intravascular Pressure2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present series of in vivo experiments in healthy subjects, were performed to investigate wall stiffness in peripheral vessels and how this modality adapts to iterative increments or sustained reductions in local intravascular pressures. Vascular stiffness was measured as changes in arterial and venous diameters, and in arterial flow, during graded increments in distending pressures in the vasculature of an arm or a lower leg. In addition, effects of intravascular pressure elevation on flow characteristics in veins, and on limb pain were elucidated. Arteries and veins were stiffer (i.e. pressure distension was less) in the lower leg than in the arm. The pressure-induced increase in arterial flow was substantially greater in the arm than in the lower leg, indicating a greater stiffness in the arterioles of the lower leg. Prolonged reduction of intravascular pressures in the lower body, induced by 5 wks of sustained horizontal bedrest (BR), decreased stiffness in the leg vasculature. BR increased pressure distension in the tibial artery threefold and in the tibial vein by 86 %. The pressure-induced increase in tibial artery flow was greater post bedrest, indicating reduced stiffness in the arterioles of the lower leg. Intermittent increases of intravascular pressures in one arm (pressure training; PT) during a 5-wk period decreased vascular stiffness. Pressure distension and pressure-induced flow in the brachial artery were reduced by about 50 % by PT. PT reduced pressure distension in arm veins by 30 to 50 %. High intravascular pressures changed venous flow to arterial-like pulsatile patterns, reflecting propagation of pulse waves from the arteries to the veins either via the capillary network or through arteriovenous anastomoses. High vascular pressures induced pain, which was aggravated by BR and attenuated by PT; the results suggest that the pain was predominantly caused by vascular overdistension. In conclusion, vascular wall stiffness constitutes a plastic modality that adapts to meet demands imposed by a change in the prevailing local intravascular pressure. That increased intravascular pressure leads to increased arteriolar wall stiffness supports the notion that local pressure load may serve as a “prime mover” in the development of vascular changes in hypertension.

  • 229.
    Lagerstedt, Marianne
    KTH, School of Technology and Health (STH), Patientsäkerhet.
    Komplexa operationer i en komplex vårdform: om ledning, ledningsbehov och möjligheter till ledning för säkrare vård i hemmet2012Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Advanced home care (ASIH) enables the patient to stay at home rather than to stay hospitalized in connection with severe medical conditions, while simultaneously this Thesis demonstrates that this is in fact not completely unproblematic and without risk. This partly because ASIH proves to be a complex form of care with many different kind of collaterally ongoing care contacts and efforts of care and concern, partly since ASIH concurrently can assume an overview over the treatment process and collaboration or cooperation between several treatment agents from different kinds of organizations and/or operations during all hours. This composes a relatively new heterogenetic and multifaceted context of care which to the professional practice means both new and less known problems within patient safety, which substantially can obstruct and rule out both the completion and the implementation of a safe home care.

    The Thesis is based upon an exploratory case study of problems within patient safety in correlation with an advanced home care, and where the research study has had its starting position in the professional practice with an interactive and qualitative research approach. The case study houses two part studies which show that the patient safety problems can be related to an intermediary and multi-organizational form of care, rather than an single operation. A command and control view upon the problems of patient safety, which the professional practice faces, show that missions within the frame of the care form ASIH can be regarded as either a complicated and not rarely a complex operation consistent with Alberts & Hayes (2007) and Brehmers (2008a; 2009c) terminology and where the assignments includes dynamic decision tasks. The case study reveals that the patient safety problems which concretely can obstruct and rule out the completion or implementation of the assignments in a safe way, can be considered related to the layout of the description of the assignments and also a lack of operative and tactical command and control level (of the handling and care of patients) in correlation with the different sorts of assignments that prevails – coincidentally as there is no suitable organization (forums of cooperation) and no appropriate IT-resources for the liaisons which effectively manages to promote and support the forms of cooperation that the character of the assignments also needs. The implicit system of conduct which comes forth through the analysis indicates that there is a need of improvement in order to enable effective command and control for a safer care, since the form of the system of conduct according to Brehmer´s (2006a,b; 2007a,b; 2008a,b; 2009c, 2010, 2011) model fails to satisfy the needs set by the function of command and control.

    The conclusion of the case study is that advanced home care should be regarded as an intermediary and multi-organizational care form which includes dynamic decision tasks and character wise complex operations contemplated per patient, thus demanding substantial command and control resources, a new point of view upon management and new auxiliary means of management in order to maintain a safe care during the implementation. The hypothesis which has been crystallized during the conclusions of the case study is that a more effective control and command and appropriate auxiliary means of command and control in real time, concerning primarily the handling of patients at the time of a change in care form, can improve the conditions of work in the professional practice and also result in more patient time, which consequently can be expected to contribute to concept of “Good care” i.g. cost effective, patient safe and dignified care.

  • 230.
    Lagerstedt, Marianne
    KTH, School of Technology and Health (STH), Medical Engineering.
    Mot nätverkssjukvård i komplex miljö: - behov av en vetenskaplig syn på ledning för säker vård och effektiv resursanvändning2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Since 2008 advanced home healthcare agencies (ASiH) in a larger Swedish county council has underwent a transformation, to become part of a coming concept: networked healthcare (NVS). NVS means that intermediate multi-organizational healthcare (IMV) will be produced often in the home, and from 2013 to an increasing number of patients in different age groups with different diagnoses and medical conditions - in large variability of needs. At the same time IMV has proved to be not simply practical to implement in a resource-efficient and patientsafe way. Based on theories from Command and Control Science the safetyproblem that arise in connection with IMV is a sign of the less known increasing need of the direction and coordination support that IMV requires.

    With a casestudy based research approach with interactive elements, different qualitative methods has been used in two phases between 2008 - 2013. The first phase is characterized by a phenomenological approach, while the second phase has a critical hermeneutic approach. Research methods includes fieldvisits with informal discussions, in-depth interviews, validation with respondents and two different methodologies for textanalysis.

    The main result shows that practical aggravating circumstances for safe care consists of lesser known and from 2013 increasing problems with direction and coordination, through expanded advanced IMV in the home as a part of NVS concept. This also as a result of inadequate and inappropriate direction and coordination support for IMV.

    The thesis concludes that the NVS represents a resource intensive health care concept, which requires a new view on the management issue and a network-related methodology for direction and coordination. This is to promote ethical, equitable, patientsafe and dignified advanced IMV so an optimized use of resources can be implemented, through shared responsibility and coordination in patientuniquely designed networkconstellations as a given work model.

  • 231.
    Lanner, Daniel
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Investigation of the boundary conditions for oblique testin of motorcycle helmets using numerical methods: with focus on the human neck and shoulder2011Licentiate thesis, comprehensive summary (Other academic)
  • 232.
    Lanner, Daniel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Investigation of the importance of the neck in oblique helmet testingManuscript (preprint) (Other academic)
  • 233.
    Larsson, Malin
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Toward increased applicability of ultrasound contrast agents2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ultrasound is one of the most widely used modalities in medical imaging because of its high cost-effectiveness, wide availability in hospitals, generation of real-time images, and use of nonionizing radiation. However, the image quality can be insufficient in some patients. Introducing a contrast agent (CA), which comprises a suspension of 2–6 mm-sized microbubbles, improves the image quality and thus the image analysis. At present, contrast-enhanced ultrasound is frequently used during standard clinical procedures such as kidney, liver, and cardiac (echocardiography) imaging. Multimodality and targeted imaging are future areas for ultrasound CAs. Multimodality imaging may improve diagnostics by simultaneously providing anatomical and functional information. Targeted imaging may allow for identification of particular diseases.

    The work within this thesis focused mainly on a novel multimodal polymer-shelled CA with the potential to be target specific. In Study I, the acoustic response was determined in a flow phantom by evaluating the contrast-to-tissue-ratio when using contrast sequences available in clinical ultrasound systems. This study showed that a high acoustic pressure is needed for optimal visualization of the polymer-shelled CA. In Study II, the in vivo performance of this CA was evaluated in a rat model, and the blood elimination time and subcellular distribution were determined. In Study III, the efficiency in endocardial border delineation was assessed in a pig model. The polymer-shelled CA had a significantly longer blood circulation time than the commercially available CA SonoVue, which is favorable for target-specific CA, in which a long circulation time increases the probability of target-specific binding. Transmission electron microscopic analysis of tissue sections from liver, kidney, spleen and lungs, obtained at different time points after CA injection showed that macrophages were responsible for the elimination of the polymer-shelled CA. A higher dose of the polymer-shelled CA was needed to obtain similar endocardial border delineation efficiency as that obtained using SonoVue. The results of Studies I–III demonstrate that the polymer-shelled CA has potential applicability in medical imaging.

    Current guidelines for contrast-enhanced echocardiography are limited to cases of suboptimal image quality or when there is a suspicion of structural abnormalities within the left ventricle. It may be hypothesized that the wider use of contrast-enhanced echocardiography may help to detect some diseases earlier. Study IV assessed the diagnostic outcomes after contrast administration in patients without indications for CA use. The myocardial wall motion score index and ejection fraction were evaluated by experienced and inexperienced readers, and a screening for left ventricular structural abnormalities was performed. More cases of wall motion and structural abnormalities were detected in the contrast-enhanced analysis. Intra- and interobserver variability was lower with the use of CAs. This study suggests that the more widespread use of CAs instead of the current selective approach may contribute to earlier detection of cardiovascular disease.

  • 234.
    Larsson, Malin
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Caidahl, Kenneth
    Winter, Reidar
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    A novel technique to visualize target specific polymeric contrast agents2011Conference paper (Other academic)
  • 235.
    Larsson, Malin
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Da Silva, Cristina
    Department of Cardiology, Karolinska Institutet, Karolinska University Hospital.
    Gunyeli, Elif
    Department of Cardiology, Karolinska Institutet, Karolinska University Hospital.
    Akebat Bin Ilami, Ali
    Department of Cardiology, Karolinska Institutet, Karolinska University Hospital.
    Szummer, Karolina
    Department of Cardiology, Karolinska Institutet, Karolinska University Hospital.
    Winter, Reidar
    Department of Cardiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    The potential clinical value of contrast-enhanced echocardiography beyond current recommendationsManuscript (preprint) (Other academic)
  • 236.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Quantification and Visualization of Cardiovascular Function using Ultrasound2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is a large need for accurate methods detecting cardiovascular diseases, since they are one of the leading causes of mortality in the world, accounting for 29.3% of all deaths. Due to the complexity of the cardiovascular system, it is very challenging to develop methods for quantification of its function in order to diagnose, prevent and treat cardiovascular diseases. Ultrasound is a technique allowing for inexpensive, noninvasive imaging, but requires an experienced echocardiographer. Nowadays, methods like Tissue Doppler imaging (TDI) and Speckle tracking imaging (STI), measuring motion and deformation in the myocardium and the vessel walls, are getting more common in routine clinical practice, but without a proper visualization of the data provided by these methods, they are time-consuming and difficult to interpret. Thus, the general aim of this thesis was to develop novel ultrasound-based methods for accurate quantification and easily interpretable visualization of cardiovascular function.

    Five methods based on TDI and STI were developed in the present studies. The first study comprised development of a method for generation of bull’s-eye plots providing a color-coded two-dimensional visualization of myocardial longitudinal velocities. The second study proposed the state diagram of the heart as a new circular visualization tool for cardiac mechanics, including segmental color-coding of cardiac time intervals. The third study included development of a method describing the rotation pattern of the left ventricle by calculating rotation axes at different levels of the left ventricle throughout the cardiac cycle. In the fourth study, deformation data from the artery wall were tested as input to wave intensity analysis providing information of the ventricular – arterial interaction. The fifth study included an in-silico feasibility study to test the assessment of both radial and longitudinal strain in a kinematic model of the carotid artery.

    The studies showed promising results indicating that the methods have potential for the detection of different cardiovascular diseases and are feasible for use in the clinical setting. However, further development of the methods and both quantitative comparison of user dependency, accuracy and ease of use with other established methods evaluating cardiovascular function, as well as additional testing of the clinical potential in larger study populations, are needed.

  • 237.
    Larsson, Matilda
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Verbrugghe, Peter
    KU Leuven.
    Smoljkić, Marija
    KU Leuven.
    Heyde, Brecht
    KU Leuven.
    Famaey, Nele
    KU Leuven.
    Herijgers, Paul
    KU Leuven.
    D'hooge, Jan
    KU Leuven.
    Assessment of longitudinal strain in the Carotid artery wall using ultrasound-based Speckle tracking - validation in a sheep model2013In: Proceedings of the IEEE International Ultrasonics symposium, 2013, 2013Conference paper (Other academic)
    Abstract [en]

    Assessment of strain in the longitudinal direction of the arterial wall has been suggested to improve the evaluation of arterial stiffness and atherosclerosis. Recently, we showed the feasibility of ultrasound speckle tracking to assess carotid longitudinal strain in-silico and in-vitro. However, validation in the more challenging in-vivo setting is still lacking. The aim of this study was to validate longitudinal strain assessment in the common carotid artery (CCA) in an animal setup. The left CCAs of five sheep were exposed during Isoflurane anesthesia and sonomicrometry crystals were sutured onto the artery wall to obtain reference longitudinal strain. Ultrasound long-axis images were recorded at baseline and hypertension (Phenylephrine) and an in-house speckle tracking algorithm was applied to estimate longitudinal strain. The estimated strain curves varied cyclically throughout the cardiac cycles, showing a lengthening of the arterial segment in systole. A significant correlation between peak systolic estimated and reference strain was found (r=0.95, p < 0.001). The results indicate the feasibility of arterial longitudinal strain assessment in-vivo using ultrasound speckle tracking.

  • 238.
    Larsson, Staffan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    When the future is here: A research report that turned over to a book project2013Conference paper (Other academic)
  • 239.
    Larsson, Staffan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Workshop in digital photomicrography2013Conference paper (Other academic)
  • 240.
    Larsson, Tore
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Future ways of distributing care and personal services2015In: The Gerontologist, ISSN 0016-9013, E-ISSN 1758-5341, Vol. 55, p. 171-171Article in journal (Other academic)
  • 241.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Accident information and priorities for injury prevention1990Doctoral thesis, comprehensive summary (Other academic)
  • 242.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Safety Management Systems: Culture, Cognition or Cash?2010In: Safety Science Monitor, ISSN 1443-8844, Vol. 14, no 2, p. Editorial-Article in journal (Other academic)
  • 243.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    The Distribution of Sprains and Strains by Gender, Age, Occupation and Industry According to the Victorian Claims Data 1996-20002001Report (Other academic)
  • 244.
    Larsson, Tore J
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    The Prevention of Hazardous Child Labour2007In: Safety Science Monitor, ISSN 1443-8844, Vol. 11, no 1, p. 1-9Article in journal (Other academic)
  • 245.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    et al,
    Forklift Literature Review2003Report (Other academic)
    Abstract [en]

    Forklift related accidents contribute a significant proportion of workplace fatalities all over the world.  No more severe is this problem than in the USA, the location where the majority of forklifts are manufactured.  “OHSA estimates forklifts cause about 85 fatal accidents per year, 34,000 accidents result in serious injury and 61,800 are classified as non-serious”. (Hall, 1996)

    Furthermore forklift accidents occur indiscriminately across all industry sectors, however a significant fatality ‘blackspot’ exists for plant and machine operators within the Manufacturing industry (NOHSC, 1998).   A high density of pedestrian workers exists within this environment, which in addition to vehicle roll-overs comprise the main accident mechanisms.  Conditions like narrowed aisleways and carrying loads were found to increase the likelihood of such accidents nearly two fold. (Collins et al (a), 1999)

    Certain risk factors were found to be inherent, due to the design and functional requirements of the forklift.  The narrow track coupled to a variable centre of gravity makes stability a primary concern whilst operating.  Cornering and the responsive steering characteristics of forklifts are two unbridled determinants of the vehicle’s stability.  Toyota was found to be the only forklift manufacturer to address the issue of forklift stability, and does so with the advent of SAS technology introduced on their new 7 Series forklift. (Thomas, 1999)

    Stability becomes even more of an issue when handling loads, especially when adjusting the mast whilst the forks are elevated.  Both Toyota and Komatsu forklifts now have an automatic mast-levelling feature, which is an initial step towards reducing the impact of this hazard (Robertson, 1999).   Further development of this feature is required so that the effects of steering actions, uneven terrain and positioning the load is represented therefore making this an even more desirable feature.

    Whilst the challenge of maintaining stability for forklifts is renowned, a great concern exists due to the absence of an effective means to warn or restrict operators from handling unsafe loads or performing unsafe actions.  Adaptation of attitude indicators as used in aviation to inform pilots of the aircraft’s dynamics, may be an example of a more effective means of relaying stability safety information rather than a basic load chart (Allstar Networks, 2000).  This could be the first stage of technological advancement, which prevents actions from occurring that may contravene the vehicle’s safety dynamics.

  • 246.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Field, Brian
    Victorian WorkCover Authority.
    Kenningham, Lance
    Victorian WorkCover Authority.
    Lee, Sharon
    Victorian WorkCover Authority.
    Falls from Heights: A report on Claims, Fatalities and Injury Severity Outcomes2000Report (Other academic)
  • 247.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Forsblom, M
    AFA Labour Market Insurances.
    Klaesson, E
    Normark, M
    Allvarliga arbetsskador och långvarig sjukfrånvaro i Sverige 20052005Report (Other academic)
  • 248.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Forsblom, M
    Normark, M
    Oldertz, C
    Allvarliga arbetsskador och långvarig sjukfrånvaro 2007: Severe work-related injury and long-term absence from work in 2007 (In Swedish)2007Report (Other academic)
  • 249.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Horberry, T
    Accident research centre, Monash University, Australia.
    Brennan, T
    Accident research centre, Monash University, Australia.
    Lambert, J
    Accident research centre, Monash University, Australia.
    Johnston, I
    Accident research centre, Monash University, Australia.
    A Guidebook of Industrial Traffic Management & Forklift Safety2003Report (Other academic)
  • 250.
    Larsson, Tore J
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Jansson, M
    Normark, M
    Oldertz, C
    Allvarliga arbetsskador och långvarig sjukfrånvaro 2008: Severe work-related injury and long-term absence from work in 2008 ( In Swedish)2008Report (Other academic)
2345678 201 - 250 of 421
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