Biomedical subjects

J Larsson

Publications and source records attributed to J Larsson.

At least 19 recordsLinked to original sources

PubMed2006

Being a young and inexperienced trainee anesthetist: a phenomenological study on tough working conditions.

BACKGROUND: Physicians at the beginning of their specialist education have been reported to be especially exposed to stress and difficult working conditions. Considerable worry has also been caused by reports about anaesthetists dying at a younger age than other specialists as well as by reports about higher than average suicide rates among anaesthetists. Maybe as a consequence, many young doctors are reluctant to choose anaesthesiology as their future specialty. The aim of this study was to investigate what difficulties trainee anaesthetists experience at work. METHODS: Nineteen trainee anaesthetists in six Swedish hospitals were interviewed. Phenomenological analysis of the interview text was performed. RESULTS: All trainees had experienced considerable, sometimes extreme demands at work. Most of them often felt insufficient and inadequate and had problems with the professional role. Support from consultants was sometimes lacking. Some trainees expressed deep feelings of loneliness and helplessness in difficult clinical situations. CONCLUSIONS: This study shows that trainee anaesthetists have to live up to high work demands, often with very little support. Because too much stress is an obstacle to professional learning, such working conditions are a hindrance to good specialist education. The first measure to be taken should be to ensure that all trainee anaesthetists always have easy access to senior cover.

Anesthesiology↗

PubMed2005

Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb.

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

Journal Article↗

PubMed2005

Atomic-scale visualization of inertial dynamics.

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

Journal Article↗

PubMed2005

Picosecond x-ray studies of coherent folded acoustic phonons in a multiple quantum well.

Coherent folded acoustic phonons in a multilayered GaSb/InAs epitaxial heterostructure were generated by femtosecond laser pulses and studied by means of ultrafast x-ray diffraction. Coherent phonons excited simultaneously in the fundamental acoustic branch and the first back-folded branch were detected. This represents the first clear evidence for phonon branch folding based directly on the atomic motion to which x-ray diffraction is sensitive. From a comparison of the measured phonon-modulated x-ray reflectivity with simulations, evidence was found for a reduction of the laser penetration depth. This reduction can be explained by the self-modulation of the refractive index due to photogenerated free carriers.

Journal Article↗

PubMed2005

Clocking femtosecond X rays.

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Journal Article↗

PubMed2004

Trainee anaesthetists understand their work in different ways: implications for specialist education.

BACKGROUND: Traditionally, programmes for specialist education in anaesthesia and intensive care have been based on lists of attributes such as skills and knowledge. However, modern research in the science of teaching has shown that competence development is linked to changes in the way professionals understand their work. The aim of this study was to define the different ways in which trainee anaesthetists understand their work. METHODS: Nineteen Swedish trainee anaesthetists were interviewed. The interviews sought the answers to three open-ended questions. (i). When do you feel you have been successful in your work? (ii). What is difficult or what hinders you in your work? (iii). What is the core of your anaesthesia work? Transcripts of the interviews were analysed by a phenomenographic approach, a research method aiming to determine the various ways a group of people understand a phenomenon. RESULTS: Six ways of understanding their work were defined: giving anaesthesia according to a standard plan; taking responsibility for the patient's vital functions; minimizing the patient's suffering and making them feel safe; giving service to specialist doctors to facilitate their care of patients; organizing and leading the operating theatre and team; and developing one's own competence, using the experience gained from every new patient for learning. CONCLUSIONS: Trainee anaesthetists understand their work in different ways. The trainee's understanding affects both his/her way of performing work tasks and how he/she develops new competences. A major task for teachers of anaesthesia is to create learning situations whereby trainees can focus on new aspects of their professional work and thus develop new ways of understanding it.

Adult↗

PubMed2004

Impact of chronic and acute high-fat feeding on acute experimental pancreatitis complicated by endotoxinaemia.

BACKGROUND: Obesity is associated with increased severity in patients with acute pancreatitis (AP). The underlying mechanisms are unknown. Genetically obese rats exhibit decreased survival rate in experimental AP, but the clinical relevance of this model of obesity may be questioned. It is proposed that development of organ failure in AP occurs in two stages: initial priming of leucocytes followed by a second inflammatory attack. The aim was to evaluate the impact of diet-induced obesity on outcome in a 'two-hit' model of AP. METHODS: Lipopolysaccharide (LPS) was injected i.p. 3 h after retrograde bile duct infusion of sodium taurocholate in rats. Three experiments were done: 1) an LPS dose-response experiment, 2) chronic high-fat feeding (HF) for 16 weeks, and 3) acute HF for 10 days. Control rats received normal chow. Obesity, morphology and survival rate were assessed. RESULTS: LPS dose-dependently decreased survival rate and increased morphological severity. HF increased weight, intra-abdominal and liver fat. Only acute HF induced hyperlipidaemia. In AP, acute obese rats exhibited less pancreatic inflammation, but total histological severity between groups was not different. In the chronic experiment only obese animals succumbed before 24 h of pancreatitis, but 72-h survival rate was not statistically different in either high-fat experiment. CONCLUSION: An addition of LPS to AP decreases survival rate and intensifies the peri-pancreatic processes. Despite significant obesity, neither hyperlipidaemia nor increased intra-abdominal or hepatic fat influenced local pancreatic injury or survival negatively. The amount of fat per se seems not to be responsible for the deleterious influence of obesity on acute pancreatitis.

Animals↗

PubMed2004

Nutritional supplementation for diabetic foot ulcers: the first RCT.

OBJECTIVE: To determine if oral nutritional supplementation improved wound healing in malnourished patients with diabetic foot ulcers when compared with a placebo. METHOD: This prospective randomised controlled double-blind trial involved patients aged over 60 with diabetes mellitus and a Wagner grade I-II foot ulcer of over four weeks' duration. Patients received either 400 ml (400 kcal) oral nutritional supplementation (n = 26) or 400 ml placebo (n = 27) daily for six months. Patients were followed monthly for six months and after one and two years. RESULTS: A third of the patients were classified as having protein-energy malnutrition at inclusion, with no difference between the two groups. Critical leg ischaemia was more common in the intervention group than in the placebo group (p = 0.008). Nine patients in the intervention group (35%) and four in the placebo group (15%) dropped out of the study (not significant). Of those who completed the study, the wound had healed at six months in eight out of 23 patients (41%) (placebo) and in seven out of 17 (35%) (intervention) (not significant). Twenty-four per cent of patients with protein-energy malnutrition at inclusion had healed at six months compared with 50% of those without it (not significant). CONCLUSION: This is the first study to evaluate the possible benefits of nutritional supplementation on diabetic foot ulcers. A third of patients were malnourished. We encountered several methodological problems and were unable to demonstrate an improved wound healing rate in these patients.

Aged↗

PubMed2003

Professional artist, good Samaritan, servant and co-ordinator: four ways of understanding the anaesthetist's work.

BACKGROUND: Evaluating clinical competence among anaesthetists has so far focused mostly on theoretical knowledge and practical skills. According to theory, however, the way anaesthetists understand their own work has also greatly influenced the development of professional competence. The aim of this study was to investigate how anaesthetists understand their work. METHODS: Nineteen Swedish anaesthetists were interviewed. The interviews were open and sought answers to three questions 1) When do you feel you have been successful in your work?; 2) What is difficult or what hinders you in your work?; and 3) What is the core of your professional anaesthesia work? Phenomenographic analysis was performed. RESULTS: Four ways of understanding the anesthesiologists' professional work were found: 1) Give anaesthesia and control the patient's vital functions; 2) Help the patient, alleviate his/her pain and anxiety; 3) Give service to the whole hospital to facilitate the work of other doctors and nurses, caring for severely ill patients; and 4) Organize and direct the operation ward to make the operations list run smoothly. CONCLUSIONS: This study shows that anaesthetists understand their work in qualitatively different ways, which can be assumed to affect their work actions and also the way their competence develops. This has implications for the education of anaesthetists; it is important to find ways of making anaesthetists in training consciously aware of the different ways their work can be understood, as this will give them better prerequisites for future competence development.

Adult↗

PubMed2003

Early community outreach intervention in children with acquired brain injury.

Ten patients with acquired brain injury were recruited over an 18 month period in the south-western health care region of Sweden in order to evaluate the costs and effectiveness of a multidisciplinary community outreach intervention programme. An experienced multidisciplinary project team was involved and patients underwent detailed functional, cognitive and motor assessments following initial contact within two weeks of injury, within six weeks of injury and at a 12-month follow-up. An individualized counselling programme was also offered. Of an expected recruitment number of 50 patients (based on epidemiological and population based figures) 10 children were reached, evaluated and followed; eight patients with traumatic brain injury (five severe, two moderate and one mild), and two patients with non-traumatic brain injury (both severe). At follow-up there was a significant improvement in motor function. No significant changes were seen in other areas of functional assessment or on neuropsychological measures although there were mild improvements in communication and behaviour functions. The financial costs per patient in the programme were deemed relatively modest compared with cost estimates of shorter-term in-patient rehabilitation. Time intensive interventions included supporting caregivers and school staff and the direct and indirect patient interventions were shown to enhance support and promote active involvement of local services.

Adolescent↗

PubMed2003

Influence of factor V Leiden on the development of neovascularisation secondary to central retinal vein occlusion.

AIMS: To investigate if the presence of factor V Leiden has an influence on the prognosis in central retinal vein occlusion (CRVO). METHODS: 166 patients with CRVO were studied retrospectively. They were tested for factor V Leiden using DNA analysis. The presence of the mutation was studied in correlation with the development of neovascular complications 1 year after the thrombotic event. RESULTS: 56 of 166 patients (34%) developed neovascular complications after 1 year. In the patients who had the studied mutation 11 of 20 (55%) had developed neovascular complications after 1 year, compared to 45 of 146 patients (31%) in the group without factor V Leiden (p=0.04). CONCLUSION: The presence of factor V Leiden seems to enhance the risk of developing neovascular complications in CRVO.

Activated Protein C Resistance↗

PubMed2002

Obstructive jaundice results in increased liver expression of uncoupling protein 2 and intact skeletal muscle glucose metabolism in the rat.

BACKGROUND: A majority of patients with pancreatic cancer have obstructive jaundice and diabetes with skeletal muscle insulin resistance. Surgery for these patients is associated with significant morbidity. Uncoupling protein 2 (UCP2) has been proposed to regulate energy expenditure and promote liver vulnerability. The effects of obstructive jaundice on muscle glucose metabolism and expression of UCP2 in liver and muscle are unknown. METHODS: Rats were operated with bile duct ligation (BDL). After 7 days, UCP2 mRNA levels were determined in liver and muscle. Simultaneously, insulin-stimulated glucose transport and glycogen synthesis in skeletal muscle were analyzed in vitro. RESULTS: The jaundiced rats lost more weight than pair-fed controls. UCP2 mRNA levels were increased 5-fold in liver but not in muscle in jaundiced rats compared to pair-fed controls. The jaundiced rats were hypoglycemic and hypoinsulinemic but demonstrated intact or enhanced insulin action on skeletal muscle glucose transport and glycogen synthesis in vitro. Muscle glycogen content was increased in the jaundiced rats. CONCLUSIONS: Experimental obstructive jaundice in the rat is associated with increased liver expression of UCP2, rapid weight loss, and intact insulin action on skeletal muscle glucose metabolism. Obstructive jaundice, by upregulated liver UCP2, may contribute to the cachexia and high surgical morbidity observed in these patients, but not to skeletal muscle insulin resistance in pancreatic cancer patients.

Animals↗

PubMed2001

The BTB/POZ domain of the regulatory proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) interacts with the novel Drosophila TAF(II) factor BIP2/dTAF(II)155.

The BTB/POZ domain is an evolutionarily conserved protein-protein interaction domain present in the N-terminal region of numerous transcription factors involved in development, chromatin remodeling, and human cancers. This domain is involved in homomeric and heteromeric associations with other BTB/POZ domains. The Drosophila BTB/POZ proteins Bric à brac 1 (BAB1) and Bric à brac 2 (BAB2) are developmentally regulated transcription factors which are involved in pattern formation along the proximo-distal axis of the leg and antenna, in the morphogenesis of the adult ovaries, and in the control of sexually dimorphic characters. We have identified partners of the BAB1 protein by using the two-hybrid system. The characterization of one of these proteins, called BIP2 for BAB Interacting Protein 2, is presented. BIP2 is a novel Drosophila TATA-box Protein Associated Factor (TAF(II)), also named dTAF(II)155. We show that the BTB/POZ domains of BAB1 and BAB2 are sufficient to mediate a direct interaction with BIP2/dTAF(II)155. This provides a direct link between these BTB/POZ transcription factors and the basal transcriptional machinery. We discuss the implications of the interaction between a BTB/POZ domain and a TAF(II) for the molecular mechanisms of transcriptional control mediated by BTB/POZ transcription factors.

Animals↗

PubMed2001

Painting of fourth, a chromosome-specific protein in Drosophila.

Chromosome-specific gene regulation is known thus far only as a mechanism to equalize the transcriptional activity of the single male X chromosome with that of the two female X chromosomes. In Drosophila melanogaster, a complex including the five Male-Specific Lethal (MSL) proteins, "paints" the male X chromosome, mediating its hypertranscription. Here, with the molecular cloning of Painting of fourth (Pof), we describe a previously uncharacterized gene encoding a chromosome-specific protein in Drosophila. Unlike the MSL proteins, POF paints an autosome, the fourth chromosome of Drosophila melanogaster. Chromosome translocation analysis shows that the binding depends on an initiation site in the proximal region of chromosome 4 and spreads in cis to involve the entire chromosome. The spreading depends on sequences or structures specific to chromosome 4 and cannot extend to parts of other chromosomes translocated to the fourth. Spreading can also occur in trans to a paired homologue that lacks the initiation region. In the related species Drosophila busckii, POF paints the entire X chromosome exclusively in males, suggesting relationships between the fourth chromosome and the X and between POF complexes and dosage-compensation complexes.

Amino Acid Sequence↗

PubMed2001

Pancreatic cancer cells require an EGF receptor-mediated autocrine pathway for proliferation in serum-free conditions.

In-vitro and in-vivo studies have shown that autocrine growth factors and receptors are frequently expressed in human malignancies. Few of these studies, however, provide evidence that the identified autocrine pathway is functional. In this study, a functional autocrine growth pathway in pancreatic cancer has been identified using an in-vitro cell culture system. When pancreatic cancer cells were grown without change of medium, proliferation was greater than when either medium was replaced frequently (HPAF, CAPAN-2, PANC-1 or SW1990) or cells were grown in the presence of the EGF receptor tyrosine kinase inhibitor AG1478 or the MEK inhibitor PD098059 (HPAF or CAPAN-2). Activity of extracellular-regulated kinases (ERK) 1 and 2 and c- jun and c- fos mRNA levels were significantly elevated in CAPAN-2 cells cultured continuously in serum-free medium. Collectively, the observations indicate that the EGF receptor and the ERK MAP kinase pathway mediate autocrine signals. In contrast to previous reports, the GRP and IGF-I receptors were shown not to be required for autocrine effects on pancreatic cancer cell proliferation. Autocrine stimulation of the EGF receptor can contribute to sustained mitogenic activity and proliferation of pancreatic cancer cells.

Cell Division↗

PubMed2001

Abnormal angiogenesis but intact hematopoietic potential in TGF-beta type I receptor-deficient mice.

Deletion of the transforming growth factor beta1 (TGF-beta1) gene in mice has previously suggested that it regulates both hematopoiesis and angiogenesis. To define the function of TGF-beta more precisely, we inactivated the TGF-beta type I receptor (TbetaRI) gene by gene targeting. Mice lacking TbetaRI die at midgestation, exhibiting severe defects in vascular development of the yolk sac and placenta, and an absence of circulating red blood cells. However, despite obvious anemia in the TbetaRI(-/-) yolk sacs, clonogenic assays on yolk sac-derived hematopoietic precursors in vitro revealed that TbetaRI(-/-) mice exhibit normal hematopoietic potential compared with wild-type and heterozygous siblings. Endothelial cells derived from TbetaRI-deficient embryos show enhanced cell proliferation, improper migratory behavior and impaired fibronectin production in vitro, defects that are associated with the vascular defects seen in vivo. We thus demonstrate here that, while TbetaRI is crucial for the function of TGF-beta during vascular development and can not be compensated for by the activin receptor-like kinase-1 (ALK-1), functional hematopoiesis and development of hematopoietic progenitors is not dependent on TGF-beta signaling via TbetaRI.

Activin Receptors, Type I↗

PubMed2001

Probing impulsive strain propagation with X-ray pulses.

Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser excitation. The surface and bulk components of the strain could be simultaneously measured due to the large x-ray penetration depth. Comparison of the experimental data with dynamical diffraction simulations suggests that the conventional model for impulsively generated strain underestimates the partitioning of energy into coherent modes.

Journal Article↗

PubMed2001

[Clostridium difficile-associated diarrhea--a growing problem in geriatric care].

From 1994 to 1998 the incidence of Clostridium difficile-associated diarrhoea (CDAD) in the Department of Geriatric Medicine, Huddinge University Hospital increased from 0.5% to 2.2% of all admissions. Corresponding figures for the whole hospital were 0.3% and 0.6%, respectively. The increase in CDAD at the Department of Geriatric Medicine was parallel with a more than doubled consumption of antibiotics. All geriatric patients with CDAD had been treated with antibiotics before onset of diarrhoea. Out of the antibiotic prescriptions 48% were a cephalosporin (mainly cefuroxim). In a matched reference group of geriatric patients 51% had been treated with antibiotics during the hospital stay. The patients with CDAD spent 27 +/- 14 days in hospital as compared to 13 +/- 9 days (P < 0.05) in the reference population.

Aged↗