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| 3. |
- Ekström, Mikael, et al.
(författare)
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Antiferromagnetism in Zn-doped La2CuO4 as observed by muon spin resonance spectroscopy
- 2001
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 0163-1829. ; 64:18, s. 1845221-1845226
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Tidskriftsartikel (refereegranskat)abstract
- The local fields seen by positive muons implanted in Zn-doped La2CuO4 show a distribution with a main peak attributed to muon sites far from the Zn ions and a satellite structure corresponding to muons residing closer to the Zn. The temperature dependence indicates a strong loss of magnetic order for Cu moments near the Zn atoms. The data can be understood in terms of a model where a Zn ion not only introduces a vacancy in the magnetic Cu lattice but also creates a RKKY-type disturbance. The electron spin polarization around the Zn ions induces a change of the magnetic moments on surrounding Cu ions. The AF lattice is found to be strongly perturbed within a radius of 10 Angstrom around each Zn ion. Possible consequences for the superconductivity of the corresponding Sr-doped materials are discussed.
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- Nygren, Andreas, 1967, et al.
(författare)
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Autoregulation of human jejunal mucosal perfusion during cardiopulmonary bypass.
- 2006
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Ingår i: Anesthesia and analgesia. - 1526-7598. ; 102:6, s. 1617-22
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Tidskriftsartikel (refereegranskat)abstract
- Animal studies have suggested that autoregulation of intestinal blood flow is severely impaired during cardiopulmonary bypass (CPB). We investigated the jejunal mucosal capacity to autoregulate perfusion during nonpulsatile CPB (34 degrees C) in 10 patients undergoing elective cardiac surgery. Changes in mean arterial blood pressure (MAP) were induced by altering the CPB flow rate randomly for periods of 3 min from 2.4 L/min/m2 to either 1.8 or 3.0 L/min/m2. Jejunal mucosal perfusion (JMP) was continuously recorded by laser Doppler flowmetry. A typical pattern of flow motion (vasomotion) was recorded in all patients during CPB. Variations in CPB flow rates caused no significant changes in mean JMP, jejunal mucosal hematocrit, or red blood cell velocity within a range of MAP from 50 +/- 15 to 74 +/- 16 mm Hg. The vasomotion frequency and amplitude was positively correlated with CPB flow rate. IV injections of prostacyclin (10 microg, Flolan) blunted vasomotion and increased JMP from 192 +/- 53 to 277 +/- 70 (P < 0.05) perfusion units despite a reduction in MAP from 59 +/- 12 to 45 +/- 10 mm Hg (P < 0.05). Prostacyclin-induced vasodilation resulted in loss of mucosal autoregulation (pressure-dependent perfusion). We conclude that autoregulation of intestinal mucosal perfusion is maintained during CPB in humans.
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- Nygren, Karina, et al.
(författare)
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Adolescent self-reported health in relation to school factors : a multilevel analysis
- 2014
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Ingår i: Journal of School Nursing. - : Sage Publications. - 1059-8405 .- 1546-8364. ; 30:2, s. 114-122
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to examine school-related determinants of self-reported health among adolescents. Questionnaire survey data comprising 4,972 students, Grades 7 through 9, from 20 schools in northern Sweden were used. Also, complimentary data about each school were collected from the Swedish National Agency for Education. Using multilevel logistic regression analyses, results showed that most variation in self-reported health was explained by individual-level differences. Truancy, bullying, and poor relations with teachers significantly increased the odds ratio of reporting poor general health, for boys and for girls. Most variables at the school level, for example, school size and student-teacher ratio, did not render significant associations with students' self-reported health. In conclusion, this study indicates that health promotion at school, including school health services, may benefit from focusing primarily on individual-level determinants of health, that is, students' relations to peers and teachers, without ignoring that bullying and weak student-teacher relationships also may induce school-level interventions.
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- Nygren, Karina, 1974-, et al.
(författare)
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Parents matter : but relations to parents do not explain gender differences in self-reported health in adolescents
- 2012
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Ingår i: Scandinavian Journal of Caring Sciences. - : Wiley. - 0283-9318 .- 1471-6712. ; 26:4, s. 643-653
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to explore whether parent-adolescent relations are associated to self-reported health of adolescents. Logistic regression analyses were performed on a cross-sectional data set consisting of 5060 adolescents, grades 7-9, from six municipalities in the northern part of Sweden. The study was approved by the Regional Ethical Review Board in Umeå, Sweden. Results showed that, in both boys and girls, experiencing low parental demands as well as perceiving the relationship quality and the communication with parents as poor were significantly associated with having poor general health, somatic complaints and feelings of stress. In general, girls scored lower on self-reported health than boys, but our findings indicate that these gender differences could not be explained by relations to parents. In conclusion, relations to parents play an important role for self-reported health of adolescents. Although no causal-effect statements can be determined in this study, it is implied that there is a need for health professionals, such as school nurses, school welfare officers, etc., to pay special attention to parent-adolescent relations in their work with adolescents.
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- Thorén, Anders, 1955, et al.
(författare)
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Cardiopulmonary bypass in humans--jejunal mucosal perfusion increases in parallel with well-maintained microvascular hematocrit.
- 2005
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Ingår i: Acta anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 49:4, s. 502-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: An imbalance between splanchnic oxygen supply and demand occurs during cardiopulmonary bypass (CPB) in man, which might disrupt the intestinal mucosal barrier function. The aim of the present study was to evaluate the effects of mild hypothermic CPB on intestinal mucosal perfusion in man undergoing cardiac surgery. Additionally we aimed to identify variables, which independently could predict changes of intestinal mucosal microcirculatory variables during CPB. METHODS: Jejunal mucosal perfusion (JMP), jejunal mucosal hematocrit (JMHt), red blood cell (RBC) velocity and arteriolar vasomotion using endoluminal jejunal laser Doppler flow metry were studied in eight cardiac surgical patients before and during CPB at a temperature of 34 degrees C. RESULTS: Cardiopulmonary bypass and the accompanied hemodilution (25-30%) induced a 44% increase in JMP (P < 0.05) and a 42% increase in RBC velocity (P < 0.01), with no change in JMHt. The oscillation amplitude of JMP, at a fundamental frequency of 2.8 cycles min(-1), increased with 175% (P < 0.05) during CPB. Splanchnic oxygen extraction increased by 64% during CPB (P < 0.05). Stepwise multiple regression analysis identified systemic hematocrit, arterial O2 and CO2 tension and splanchnic oxygen extraction as independent predictors of RBC velocity during CPB (R2=0.63, P < 0.001). The oscillation amplitude of JMP was predicted by RBC velocity and splanchnic oxygen extraction (R2= 0.68, P <0.0001). CONCLUSIONS: The increase in RBC velocity and enhanced arteriolar vasomotion, as well as maintained jejunal mucosal hematocrit, are microcirculatory, compensatory mechanisms for the splanchic oxygen supply/demand mismatch seen during cardiopulmonary bypass in humans.
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| 9. |
- Alsved, Malin, et al.
(författare)
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Droplet, aerosol and SARS-CoV-2 emissions during singing and talking
- 2021
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Konferensbidrag (refereegranskat)abstract
- IntroductionAs the pandemic continues to spread, more knowledge is needed about the viral transmission routes. Several super spreading events during the Covid-19 pandemic have been linked to singing in choirs and talking loud. However, in the beginning of the pandemic there was only one study about emitted aerosols and droplets from singing, published in 1968, and only a handful on emissions from talking. Therefore, we conducted a study to measure the aerosol and droplet emissions from talking and singing. We also evaluated the emissions from singing when wearing a face mask.We have further developed our setup so that we collect the aerosol particles from Covid-19 infected patients that are talking and singing, and analyze our samples for SARS-CoV-2, the virus causing Covid-19.MethodTwelve healthy singers (7 professionals, 5 amateurs) were included in the first study part on quantifying the amount of emitted aerosols and droplets. The singers were singing or talking a short consonant rich text repeatedly at a constant pitch with their face in the opening of a funnel. The aerosol particle size and concentration was measured from the other end of the funnel using an aerodynamic particle sizer (APS, 3321, TSI Inc). In addition, the amount of un-evaporated droplets were captured with a high-speed camera and quantified using image analysis.During February and March 2021 we will collect aerosol particles from patients with confirmed Covid-19 that are singing and talking into a funnel. We will use a growth tube condensation collector, a BioSpot (Aerosol Devices), operating at 8 L min-1, and a NIOSH BC-251 cyclone sampler operating at 3.5 L min-1 (TISCH Environmental). The BioSpot collects the whole range of exhaled aerosol particles with high (95%) efficiency into liquid, and the NIOSH cyclone sampler collects particles into three size fractions: <1 µm (filter), 1-4 µm (liquid), >4 µm (liquid). The APS is again used to measure size and concentration of the emitted aerosol particles, so that emissions from infected test subjects can be compared with those of the healthy test subjects. Air samples will be analyzed for detection of SARS-CoV-2 genes, and if possible, SARS-CoV-2 infectivity in cell cultures.ResultsAerosol particle emissions from healthy test subjects were significantly higher during normal singing (median 690, range [320–2870] particles/s) than during normal talking (270 [120–1380] particles/s) (Wilcoxon’s signed rank test, p=0.002). Loud singing produced even more aerosol particles (980 [390–2870] particles/s) than normal singing (p=0.002). The amount of non-evaporated droplets detected by the high-speed camera setup showed similar results: more droplets during loud singing or talking. For both aerosol particle concentrations and droplet numbers, the levels were reduced by on average 70-80% when wearing a surgical face mask.ConclusionsSinging and talking give rise to high aerosol and droplet emissions from the respiratory tract. This is likely an important transmission route for Covid-19. In our upcoming part of the study we hope to determine how much SARS-CoV-2 that is emitted during these social activities.
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| 10. |
- Bellner, Lars, 1973, et al.
(författare)
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A proinflammatory peptide from herpes simplex virus type 2 glycoprotein G affects neutrophil, monocyte, and NK cell functions
- 2005
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Ingår i: J Immunol. - : American Association of Immunologists. ; 174:4, s. 2235-2241
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Tidskriftsartikel (refereegranskat)abstract
- We have identified a synthetic peptide derived from the secreted portion of HSV type 2 glycoprotein G, denoted gG-2p20, which has proinflammatory properties in vitro. The gG-2p20 peptide, corresponding to aa 190-205 of glycoprotein G-2, was a chemoattractant for both monocytes and neutrophils in a dose-dependent fashion, and also induced the release of reactive oxygen from these cells. The receptor mediating the responses was identified as the formyl peptide receptor. The gG-2p20-induced activation of phagocytes had a profound impact on NK cell functions. The reactive oxygen species produced by gG-2p20-activated phagocytes both inhibited NK cell cytotoxicity and accelerated the apoptotic cell death in NK cell-enriched lymphocyte populations. Hence, we have for the first time been able to identify a potential function of the secreted portion of HSV-2 glycoprotein G. We propose that the proinflammatory gG-2p20 peptide identified could contribute to a reduced function and viability of NK cells during HSV-2 infection due to its ability to recruit and activate phagocytic cells.
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